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Copper Indium Diselenide

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With 19.5% efficiency under standard test conditions, the best CIS cell is about as efficient as the best polycrystalline-silicon cell. The potential for high module efficiencies and low cost has led to a large increase in private investment. However, the technology still has barriers to address before it will succeed in the marketplace.

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Journal Articles

Conference Papers

Post Date	05/30/2008
Title	THE ROLE OF POLYCRYSTALLINE THIN-FILM PV TECHNOLOGIES IN COMPETITIVE PV MODULE MARKETS
Link	(PDF 351 KB) Download Acrobat Reader.
Authors	B. Von Roedern, H. S. Ullal
Description	This paper discusses the developments in thin-film PV technologies. It provides an outlook on future commercial module efficiencies achievable based on today?s knowledge about champion cell performance. It also provides a relative cost comparison of thin-film and wafer/ribbon based Si PV modules. In 2007, about 65% of the modules produced in the US were thin-film modules when amorphous silicon modules are also considered.
Venue	Presented at the 33rd IEEE PVSC Conference, San Diego, CA 05/12-16/2008
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2008

Post Date	09/28/2007
Title	THIN FILM CIGS AND CDTE PHOTOVOLTAIC TECHNOLOGIES: COMMERCIALIZATION, CRITICAL ISSUES, AND APPLICATIONS
Link	(PDF 725 KB) Download Acrobat Reader.
Authors	H. S. Ullal, B. Von Roedern
Description	We report here on the major commercialization aspects of thin-film photovoltaic (PV) technologies based on CIGS and CdTe (a-Si and thin-Si are also reported for completeness on the status of thin-film PV). Worldwide silicon (Si) based PV technologies continues to dominate at more than 94% of the market share, with the share of thin-film PV at less than 6%. However, the market share for thin-film PV in the United States continues to grow rapidly over the past several years and in CY 2006, they had a substantial contribution of about 44%, compared to less than 10% in CY 2003. In CY 2007, thin-film PV market share is expected to surpass that of Si technology in the United States. Worldwide estimated projections for CY 2010 are that thin-film PV production capacity will be more than 3700 MW. A 40-MW thin-film CdTe solar field is currently being installed in Saxony, Germany, and will be completed in early CY 2009. The total project cost is Euro 130 million, which equates to an installed PV system price of Euro 3.25/-watt averaged over the entire solar project. This is the lowest price for any installed PV system in the world today. Critical research, development, and technology issues for thin-film CIGS and CdTe are also elucidated in this paper.
Venue	22nd EC PVSEC, Milano, Italy Sep 3-7, 2007, paper presented
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2007

Post Date	10/11/2007
Title	STUDY OF THE ELECTRONIC PROPERTIES OF MATCHED NA-CONTAINING AND NA-FREE CIGS SAMPLES USING JUNCTION CAPACITANCE METHODS
Link	(PDF 151 KB) Download Acrobat Reader.
Authors	P. T. Erslev, A. F. Halverson, J. D. Cohen, W. N. Shafarman
Description	Junction capacitance methods were used to examine a matched pair of Cu(InxGa1-x)Se2 (CIGS) thin film solar cells, one with Na incorporated into the absorber and the other with a diffusion barrier to inhibit the Na incorporation from the soda-lime glass. Typical cells showed a 50% increase in efficiency with the addition of Na to the devices. Forward biased admittance spectroscopy revealed a large defect density located near the CdS/CIGS heterojunction in the Na-less samples not present in the Na samples. This defect may be responsible for the loss in Voc which contributes to the loss in efficiency when Na is not added to the devices. Drive Level Capacitance profiles revealed free carrier densities of 3�10^14 cm^-3 and 1.1�10^14 cm-3 for the Na and Na-less samples, respectively. Transient photocapacitance spectra also showed interesting differences between the samples, but nothing significant enough to account for the magnitude of loss in efficiency.
Venue	MRS Spring Meeting, San Francisco 04/2007
Source	University of Oregon
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	04/2007

Post Date	04/30/2007
Title	OUTDOOR MONITORING AND HIGH VOLTAGE BIAS TESTING OF THIN FILM PV MODULES
Link	(MS Word 64 KB)
Author	N. G. Dhere
Description	Limitations of accelerated testing to predict all possible degradation modes and mechanisms in the photovoltaic PV modules necessitate that actual outdoor monitoring and testing of PV modules be performed out-doors. For this reason, thin film PV modules from leading US thin film PV manufacturers namely, First Solar (Glass/CdTe/Glass), Shell Solar Glass/CIS/Glass), Shell Solar New (Glass/CIGS/Glass), United Solar (a-Si:H on flexible substrate), Energy Photovoltaics (Glass/a-Si:H/Glass) and Global Solar (CIS on flexible substrate) with additional one crystalline silicon module are being tested. The goal is to assess their performance in the hot and humid climate of Florida and to correlate the PV performance with the meteorological parameters namely, solar irradiance, temperature, relative humidity, wind speed, etc. Statistical data analysis of the recorded data is carried out on a daily basis and on a monthly basis with PVUSA type regression analysis. Current-voltage characteristics (I-V) of module arrays taken on a regular basis complement the results obtained with continuous data monitoring. Moreover, high voltage bias testing of the modules is carried out to study behavior of leakage currents and detect any packaging material and processing flaws and consequently the module reliability.
Venue	DOE Solar Technology Review Meeting, Denver, CO, 4/17-19/2007
Source	FLorida Solar Energy Center
Document Type	Conference Papers (Word document)
Resource Date	03/2007

Post Date	04/30/2007
Title	&NBSP; VOLTAGE DEFICIT IN THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 46 KB)
Author	J. R. Sites
Description	The highest reported efficiency for thin-film CIGS solar cells is 3% larger than the highest seen with CdTe cells. The lower CdTe efficiency is the result of a much larger voltage deficit between CdTe cells and crystalline cells of similar band gap. The explanation for the difference is that CIGS has a natural energy barrier, which repels holes from grain boundaries, but CdTe does not. Significant efficiency increases in CdTe cells will therefore likely require new structures with full absorber depletion and electron reflection at the back contact.
Venue	DOE Solar Technology Review Meeting, Denver, CO 4/17-17/2007
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	03/2007

Post Date	10/26/2006
Title	BOS COST SAVINGS NEEDS AND POTENTIAL FOR LARGE SCALE GROUND BASED PV SYSTEMS UNTIL 2010
Link	(PDF 495 KB) Download Acrobat Reader.
Author	M. Bachler
Description	More and more large scale ground based systems were implemented with thin-film modules in the past years in Germany. Based on module pricing thin film modules appear to be very attractive for this type of application. However there are quite significant differences in balance-of-system (BOS) costs within different c-Si and thin film (TF) module types, which have a high impact on total system costs. The BOS cost portion is significantly higher for systems with TF modules compared to c-Si modules. Existing c-Si modules and BOS components were developed and optimized to achieve cost savings in the past decades already a lot. TF modules as well as the related BOS components are at the very beginning of this development so the cost saving potential ? especially for BOS costs is considered to be significantly higher for TF module based systems. Since a 6.5% degression in the feed-in tariff is required in the German EEG for ground based systems a high cost reduction pressure is imposed on total system costs. The results of BOS cost savings achieved already will be demonstrated for a sample thin-film module.
Venue	Dresden World Conference
Source	Phonix SonnenStrom AG
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2006

Post Date	05/22/2006
Title	TECHNOLOGY CHOICE AND THE COST REDUCTION POTENTIAL OF PHOTOVOLTAICS
Link	(PDF 116 KB) Download Acrobat Reader.
Authors	J. E. Trancik, K. Zweibel
Description	We use a combination of system component analyses and individual experience curves for crystalline silicon (x-Si) modules, thin-film (TF) modules, and the balance of system (BOS) components, to compare future growth scenarios for photovoltaics (PV). The growth rates of TF and x-Si technologies are varied, while overall PV growth is held constant at 30%. For each of these scenarios, we estimate the total investment required for PV to reach a break-even point with fossil fuel based generation; and we investigate the intrinsic/lowest achievable costs from an analysis of potential materials, processing, and efficiency improvements. Our results show that a high growth rate (50 to 70% per year) of new technologies with low intrinsic costs could decrease the total investment required to reach break-even by up to 70 billion USD, as compared to a scenario where x-Si continues to dominate the market. Furthermore, the system component analysis indicates that existing TF modules can reach the low cost levels assumed in the experience curve model. These results suggest that the future growth of photovoltaics (PV) is dependent on which PV technologies grow most rapidly. New, low intrinsic cost technologies that are successfully able to enter the market could dramatically increase the potential for PV to become a globally significant energy conversion technology within the next two decades.
Venue	Trancik and Zweibel, WCPEC-4 2006
Sources	National Renewable Energy Laboratory; Santa Fe Institute
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	05/18/2006
Title	HIGH-EFFICIENCY CDTE AND CIGS THIN-FILM SOLAR CELLS: HIGHLIGHTS AND CHALLENGES
Link	(MS Word 602 KB)
Authors	R. Noufi, K. Zweibel
Description	Thin-film photovoltaic (PV) modules of CdTe and Cu(In,Ga)Se2 (CIGS) have the potential to reach cost-effective PV-generated electricity. These technologies have transitioned from the laboratory to the market place. Pilot production and first-time manufacturing are ramping up to higher capacity and enjoying a flood of venture-capital funding. CIGS solar cells and modules have achieved 19.5% and 13% efficiencies, respectively. Likewise, CdTe cells and modules have reached 16.5% and 10.2% efficiencies, respectively. Even higher efficiencies from the laboratory and from the manufacturing line are only a matter of time. Manufacturing-line yield continues to improve and is surpassing 85%. Long-term stability has been demonstrated for both technologies; however, some failures in the field have also been observed, emphasizing the critical need for understanding degradation mechanisms and packaging options. These two thin-film technologies have a common device/module structure: substrate, base electrode, absorber, junction layer, top electrode, patterning steps for monolithic integration, and encapsulation. The monolithic integration of thin-film solar cells can lead to significant manufacturing cost reduction compared to crystalline Si technology. The CdTe and CIGS modules share common structural elements. In principle, this commonality should lead to similar manufacturing cost per unit area, and thus, the module efficiency becomes the discriminating factor that determines the cost per watt. The long-term potential of the two technologies require R&D emphasis on science and engineering-based challenges to find solutions to achieve targeted cost-effective module performance, and in-field durability. Some of the challenges are common to both, e.g., in-situ process control and diagnostics, thinner absorber, understanding degradation mechanisms, protection from water vapor, and innovation in high-speed processing and module design. Other topics are specific to the technology, such as lower-cost and fast-deposition processes for CIGS, and improved back contact and voltage for CdTe devices.
Venue	WPEC4, Hawaii
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	05/2006

Post Date	08/25/2006
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAICS: FROM THE LABORATORY TO SOLAR FIELDS
Link	(PDF 682 KB) Download Acrobat Reader.
Authors	B. Von Roedern, H. S. Ullal, K. Zweibel
Description	We review the status of commercial polycrystalline thin-film solar cells and photovoltaic (PV) modules, including current and projected commercialization activities. Major technical progress has occurred in the area of thin-film PV technologies, particularly those based on cadmium telluride (CdTe) and copper indium diselenide (CuInGaSe2)
Venue	Presented at the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion (WCPEC-4) Waikoloa, Hawaii May 7?12, 2006 Conference Paper NREL/CP-520-39838 May 2006
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	11/17/2005
Title	LOW TOXIC PROCESSING OF THIN AND ULTRA-THIN CIGSS ABSORBER SOLAR CELLS
Link	(MS Word 1.6 MB)
Author	N. G. Dhere
Description	CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells were prepared on molybdenum coated glass substrates. A low toxic approach using diethylselenide (DESe) as a selenium source was used for selenization of metallic precursors. A compact and large-grain absorber layer was produced by heating the elemental stack at 475-500oC in the diluted DESe gas. The threshold limit value (TLV) for DESe is 5 times less stringent than that of H2Se. After stabilizing deposition and selenization/sulfurization parameters on a 2.75 ?m thick absorber layer, preliminary experiments were carried out on an ultra-thin (<1 micrometer) absorber to reduce In consumption. Cells with selenide-free chalcopyrite were prepared by sulfurization and a world record Voc of 830 mV was obtained on CuIn1-xGaxS2 (Fig 5). The efficiency (11.99 %) is the highest ever demonstrated using sputtering technique for the metal precursor deposition.
Venue	Solar Technology Review Meeting, Denver, CO 11/7-10/2005, CIS paper from FSEC
Source	FLorida Solar Energy Center
Document Type	Conference Papers (Word document)
Resource Date	11/2005

Post Date	10/20/2005
Title	PROCESS TOLERANCES IN ROLL-TO-ROLL MANUFACTURING OF CIGS-BASED PHOTOVOLTAICS ON FLEXIBLE SUBSTRATES
Link	(PDF 65 KB) Download Acrobat Reader.
Authors	M. E. Beck, et al.
Description	Two- and three-stage co-evaporation have come to be viewed as benchmark laboratory methods for CuInxGa1-xSe absorber deposition. Although quite successful and relatively easy to implement on a small R&D scale, scale-up to a commercial level proves to be challenging. Yet, large area, continuous manufacturing processes represent the most economically attractive path for thin-film PV commercialization. Large area, continuous processes necessarily differ substantially from laboratory methods, and direct process transfer is not feasible. For implementation of viable, large scale PV manufacturing methods on low-cost substrates it is necessary to understand the tolerance of the established laboratory processes to variations in deposition procedures, as they apply to low-cost roll-to-roll processing onto lightweight stainless steel foils. The success of this approach is impressively demonstrated as Global Solar Energy has achieved 90% production yield and an average production efficiency of 10%, with peak efficiencies exceeding 13% at the large-area cell level.
Venue	DOE Solar Review 2005
Source	Global Solar Energy
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	10/18/2005
Title	GROWTH OF CU(INGA)(SES)2 BY THE REACTION OF CU-GA-IN PRECURSORS IN H2SE AND H2S
Link	(MS Word 319 KB)
Authors	G. Hanket, R. W. Birkmire, W. N. Shafarman
Description	Critical issues for the formation of Cu(InGa)(SeS)2 films by the selenization or sulfization reactions of Cu-Ga-In precursor films are investigated. The phases present in the metal precursors after annealing at 450�C were Cu, In, CuIn and Cu9(In1?xGax)4 . Films reacted in hydrogen selenide (H2Se) or hydrogen sulfide (H2S) were characterized and unreacted intermetallic Cu-Ga or Cu-In phases respectively were identified at the back of the films. This indicates a reaction preference of Se with In, and S with Ga. Homogenization of the Ga using a two-step selenization/sulfization process that takes advantage of this reaction preference was confirmed and devices with VOC > 0.64 V and eff. > 13 % were demonstrated
Venue	Solar Program Review 2005
Source	University of Delaware
Document Type	Conference Papers (Word document)
Resource Date	10/2005

Post Date	10/20/2005
Title	A REVIEW OF RISKS IN THE SOLAR ELECTRIC LIFE-CYCLE
Link	(PDF 642 KB) Download Acrobat Reader.
Authors	V. Fthenakis, H. C. Kim
Description	Early studies of risks in the life cycle of solar electric technologies do not represent their current stage of development. Our study updates the data used in previous studies and also accounts for the full life-cycle of photovoltaics. We show that the non-radiological risks of the solar electric- and nuclear-life cycles are approximately equal. This contradicts the conclusions of some earlier studies according to which the former presented much greater occupational and public non-radiological risks than the latter.
Venue	Brussels 2005
Source	Brookhaven National Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	06/13/2005
Title	IMPLICATIONS OF EUROPEAN ENVIRONMENTAL LEGISLATION FOR PHOTOVOLTAIC SYSTEMS
Link	(PDF 434 KB) Download Acrobat Reader.
Authors	M. J. De Wild-Scholten, K. Wambach, E. A. Alsema, A. Jager-Waldau
Description	An overview is given of European environmental legislation which is effective now or proposed and which may have implications for the photovoltaic industry. The focus will be on legislation, which has been implemented already in national law, like the WEEE (waste electrical and electronic equipment)- and ROHS Reach (Registration, Evaluation, Authorisation and Restriction of Chemicals), F-gases (regulation on certain fluorinated greenhouse gases) and EuP (eco-design requirements for energy-using products). A change of the module design, with the research, development, implementation and certification necessary to be able to produce photovoltaic systems that comply with such legislation, may be very time-consuming and expensive. Therefore a pro-active approach by the PV community is desirable. Environmental life cycle thinking and eco-design is becoming increasingly important as part of the European product and waste policy and will have its impact on the PV industry as well. Design-for-recycling must be encouraged to allow for an easy, cost-effective disassembly, with a high retrieval of for instance the precious crystalline silicon solar cells. A closed production cycle, i.e. guaranteed take back system, would probably prevent the commission as well as member states to impose legislative measures.
Venue	20th European PVSC Barcelona
Sources	Deutsche Solar; Energy Research Centre of the Netherlands
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/10/2005
Title	THE POTENTIAL FOR HIGH PERFORMANCE IN CIGS SOLAR CELLS: A LABORATORY PERSPECTIVE
Link	(MS Word 566 KB)
Authors	K. Ramanathan, et al.
Description	We present a summary of our work with the preparation of CIGS absorbers which has led to the fabrication of record-efficiency solar cells. The use of the three-stage process in conjunction with composition monitoring facilitates the fabrication of solar cell with efficiencies between 18% and 19.5% for absorber bandgap in the range of 1.1?1.2 eV. It is possible to maintain high open-circuit voltages and high fill factors, and the efficiency gains can be correlated to low diode factors and low junction recombination current. In the second part of this paper, we describe our recent results in reducing absorber thickness and low-temperature deposition. Our preliminary results on absorbers grown from low-purity source materials show promise of reducing the cost of fabricating the absorber.
Venue	20th European PVSC Barcelona, 2005
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	06/2005

Post Date	06/29/2005
Title	NREL PAPERS FOR THE PVSC IN ORLANDO, 2005
Link	(MS Word 41 KB)
Author	N/A
Description	Links to about 20 papers in CIS, CdTe, a-Si, thin Si and reliability.
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	06/2005

Post Date	08/26/2005
Title	DESIGN CONSIDERATIONS AND IMPLEMENTATION OF VERY-LARGE SCALE MANUFACTURING OF CIGS SOLAR CELLS AND RELATED PRODUCTS
Link	(PDF 1.4 MB) Download Acrobat Reader.
Authors	J. Tuttle, et al.
Description	Discrete CIGS solar cells on flexible metal substrates offer an alternative to wafer-Si based cells. The manufacture of this cell technology additionally offers capital cost, throughput and yield advantages over the manufacture of either wafer-Si or traditional monolithically integrated thin-film modules. Economies of scale and volume can be achieved with the implementation of gigawatt-scale manufacturing. Likewise, vertical integration within the production line to include In refinement, steel substrate finishing, source material synthesis and formation, as well as module packaging materials (either glass and Al or plastic) provide for optimization of cost and supplychain issues.
Venue	Proceedings of the 20th European Photovoltaic Solar Energy Conference and Exhibition ? Barcelona, Spain ? June 2005
Source	DayStar Technologies
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	03/03/2005
Title	TOWARDS THE DEVELOPMENT OF FLEXIBLE CIGS SOLAR CELLS ON POLYMER FILMS WITH EFFICIENCY EXCEEDING 15%
Link	(PDF 1.1 MB) Download Acrobat Reader.
Authors	D. Bremaud, et al.
Description	Development of Cu(In,Ga)Se2 (called CIGS) solar cells on polymers is challenging because of the thermo-physical properties of layers and substrates. CIGS layers of suitable structural and opto-electronic properties should be grown at low temperature (< 500�C) as polyimides tend to degrade at higher deposition temperatures. Additionally, a method for controlled incorporation of an optimum amount of Na in CIGS is needed for highefficiency cells since polyimides do not contain Na. Solar cells were developed on commercially available Upilex foils. CIGS layers were grown by evaporation of elemental Cu, In, Ga and Se at different substrate temperatures. Na from a NaF film was incorporated into CIGS layers with a post-deposition diffusion method that is suitable for in-line production of solar cells. Independent measurements have confirmed 14.1% efficiency under simulated AM1.5 standard test conditions. This is the highest efficiency reported to date for any kind of solar cell grown on polymer films. An average reflectance loss of about 13% was measured for these cells. Application of a commonly used antireflection coating would enable more than 15% efficiency flexible CIGS solar cells on polyimide foils.
Venue	IEEE PVSC
Source	Swiss Federal Institute of Technology
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	02/2005

Post Date	03/03/2005
Title	THE EFFECT OF MO MORPHOLOGY ON THE PERFORMANCE OF CU(IN,GA)SE2 THIN FILMS
Link	(PDF 1.5 MB) Download Acrobat Reader.
Author	D. C. Fisher
Description	The properties of sputtered and electron-beam evaporated Mo are compared, and the resulting impacts on performance of co-evaporated CIGS devices deposited on each type of back contact are investigated. In past studies, the effect of Mo on Cu(In,Ga)Se2 device efficiency has been attributed largely to control of sodium diffusion from the glass. To verify this hypothesis, sodium-free Al2O3 substrates were utilized. Despite lack of Na in the substrate ? Na was provided as NaF on the Mo layer ? significant differences in device performance between the two types of Mo were observed. Purely resistive effects are ruled out by sheet resistance measurements, and comparison of current-voltage parameters. Negative contributions due to diffusion of harmful impurities from the substrate can be eliminated based on secondary ion mass spectroscopy results. These findings lead to the deduction of device performance dependency on Mo morphology.
Venue	IEEE PVSC
Source	Global Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	02/2005

Post Date	03/03/2005
Title	VARIATIONS OF THIOACETAMIDE TREATMENTS ON CIGS SOLAR CELLS ON STAINLESS STEEL SUBSTRATES ? CORRELATIONS TO DEVICE PERFORMANCE
Link	(PDF 341 KB) Download Acrobat Reader.
Author	W. K. Batchelor
Description	The details of design of experiment (DOE) studies involving thioacetamide treatment performed on Cu(In1-xGax)Se2 (CIGS) deposited on stainless steel are discussed. CIGS films were treated in an aqueous InCl3/thioacetamide (CH3CSNH3) bath varying time, temperature and salt as well as CH3CSNH3 concentration in order to determine the optimum conditions for surface sulfurization. Subsequent device completion employing a CBD CdS buffer was performed under nominally identical conditions. The resulting devices were compared on the basis of deposition conditions including untreated control specimens. Device efficiencies in this study ranged from 6 to 11% and did not show significant improvement over untreated controls. Procedures, results, and possible causes for disagreement with earlier studies are discussed.
Venue	IEEE
Sources	Global Solar; ITN Energy Systems
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	02/2005

Post Date	03/03/2005
Title	XPS AND UPS INVESTIGATION OF NH4OH-EXPOSED CU(IN,GA)SE2 THIN FILMS
Link	(PDF 518 KB) Download Acrobat Reader.
Authors	C. L. Perkins, et al.
Description	Photoelectron spectroscopy was used to determine the compositional and electronic changes occurring in Cu(In,Ga)Se2 thin films as a result of immersion in aqueous ammonia solution. We find that NH4OH-treated CIGS surfaces are preferentially etched of indium and gallium, resulting in the formation of a thin layer of a degenerate Cu-Se compound that we tentatively identify as Cu2Se. The work function of ammonia-treated samples is found to increase by 0.6 eV relative to as-grown CIGS thin films. The uniformity of chemical bath effects (etching & deposition) was found to be improved by the addition to the bath of a non-ionic surfactant. Initial device results show that the new surfactant-based chemical bath deposition (CBD) method may lead to better and thinner CdS buffer layers.
Venue	IEEE PVSC
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	02/2005

Post Date	03/03/2005
Title	ADVANCEMENTS IN FLEXIBLE CIGS MODULE MANUFACTURING
Link	(PDF 1.4 MB) Download Acrobat Reader.
Authors	M. E. Beck, et al.
Description	Roll-to-roll (RTR) manufacturing of consistent photovoltaic (PV) material over 1000-ft long metal foil lots has been realized at Global Solar Energy (GSE). Development of robust sensors and in-situ, real-time process control strategies for all thin-film coating (TFC) steps has enabled Global Solar to achieve manufacturing yields above 90%. In turn, reliable processing conditions enable rapid progress using well-controlled experiments designed for device optimization. Average large-area cell efficiency now exceeds 10%. Efficiency and yield have also been increased at the module level through improved fabrication methods. Flexible modules attain a power-toweight ratio of 40W/kg and aperture area efficiencies exceeding 11%. Real-time and accelerated stress tests investigating product reliability are underway.
Venue	IEEE
Source	Global Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	03/03/2005
Title	THE EFFECT OF MO MORPHOLOGY ON THE PERFORMANCE OF CU(IN,GA)SE2 THIN FILMS
Link	(PDF 1.5 MB) Download Acrobat Reader.
Authors	D. C. Fisher, et al.
Description	The properties of sputtered and electron-beam evaporated Mo are compared, and the resulting impacts on performance of co-evaporated CIGS devices deposited on each type of back contact are investigated. In past studies, the effect of Mo on Cu(In,Ga)Se2 device efficiency has been attributed largely to control of sodium diffusion from the glass. To verify this hypothesis, sodium-free Al2O3 substrates were utilized. Despite lack of Na in the substrate ? Na was provided as NaF on the Mo layer ? significant differences in device performance between the two types of Mo were observed. Purely resistive effects are ruled out by sheet resistance measurements, and comparison of current-voltage parameters. Negative contributions due to diffusion of harmful impurities from the substrate can be eliminated based on secondary ion mass spectroscopy results. These findings lead to the deduction of device performance dependency on Mo morphology.
Venue	IEEE
Source	Global Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2005

Post Date	09/27/2005
Title	DAMP HEAT STABILITY OF CHALCOPYRITE MINI-MODULES: EVALUATION OF SPECIFIC TEST STRUCTURES
Link	(PDF 77 KB) Download Acrobat Reader.
Authors	J. Klaer, et al.
Description	Damp heat stress (85% relative humidity at 85 �C) has been used to test long term stability of CIS thin film photovoltaic devices. Two CIS absorber types have been examined, CuInS2 and Cu(In,Ga)Se2. Module degradation is dominated by an increase of the series resistance Rs. In order to get information about the ZnO sheet resistance Rsq and the Mo/ZnO contact resistance Rc, which are the most important contributions to Rs, specially designed transmission-line test structures are used. Degradation of Rc strongly depends on the point of time when the second scribe for integrated series connection, P2, is made, while degradation of Rsq is strongly affected by the underlying absorber layer. Module-type solar cells without metal grid and complete mini-modules have been exposed to the same damp heat stress and yield additional information about degradation of other electrical parameters.
Venue	2005 IEEE.
Source	Hahn Meitner
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/15/2005
Title	EARLY PERFORMANCE FOR THE ROOF-MOUNTED, 20-KW THIN FILM CDTE PV-ARRAY AT JASPER RIDGE
Link	(PDF 364 KB) Download Acrobat Reader.
Authors	J. H. Scofield, et al.
Description	Here we report early performance for the grid-connected, 20-kW CdTe PV array installed on the roof of the Leslie Shao-ming Sun Field Station at the Jasper Ridge Biological Preserve. The array was installed in May 2002. Data are reported for 20-mos beginning April 2003. The array originally consisted of 275, BP Solar 80W thin-film CdTe modules arranged in 11-module strings. The monitoring system logged data from 9 sensors on 1-min intervals. Monitoring showed problems with maximum power tracking associated with module degradation, ele-vated module temperatures, and the finite voltage window of the 208VAC-3p inverter. The problems were addressed in May 2004 by re-wiring the array and reprogramming the inverter, resulting in a 20% increase in energy production.
Venue	IEEE PVSC
Source	Oberlin College
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/07/2005
Title	THE ROLE OF POLYCRYSTALLIN THIN-FILM PV TECHNOLOGIES FOR ACHIEVING MID-TERM MARKET-COMPETITIVE PV MODULES
Link	(MS Word 123 KB)
Authors	B. Von Roedern, K. Zweibel
Description	Using efficiency as the main parameter, projecting the cost competitiveness of thin films and x-Si. Current commercial status of CuInSe₂ alloys (collectively, CIS) and CdTe-based photovoltaic (PV) modules, comparing the performance of commercial products with the results achieved for solar cell and prototype module champions. We provide an update for these PV cell and module technologies, and also compare CIS and CdTe performance levels to the results achieved by the crystalline Si PV industry. This comparison shows that CIS and CdTe module technology presently offers the best (and perhaps only) approach for significantly exceeding the cost/performance levels established by crystalline Si PV technologies. A semi-empirical methodology is used for comparing "champion" solar cell and prototype module data with performance achieved on manufacturing lines. Using a conservative assumption that thin-film technologies will eliminate the 40% of PV module costs arising from the Si wafer or ribbon, we estimate the future performance of all established PV module candidates, and conclude that, based on 2004 knowledge about each PV technology, CIS and CdTe should provide cost-competitive advantages over crystalline Si.
Venue	IEEE PV Specialists Conference, 2004
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	03/22/2005
Title	QUANTIFICATION OF LOSSES IN THIN-FILM CDS/CDTE SOLAR CELLS
Link	(MS Word 3.5 MB)
Authors	S. Demetsu, J. R. Sites
Description	Quantification of solar cell losses can identify promising pathways for further cell improvements. This paper expands earlier work and applies it specifically to CdS/CdTe cells. For the analysis we have defined four cells: The Target cell is one that should be possible with current industrial processes. The Production cell is typical of today?s production. The Record cell has the highest efficiency (16.5%) reported to date. The Ideal cell has the highest theoretical performance for CdTe. The systematic technique of separating losses, referred to as third level metrics, breaks current, voltage, and fill-factor losses down into their individual loss mechanisms. The losses are expressed both as the deficiency in the specific parameter and as the impact on cell efficiency. The latter allows clear identification of the most significant losses.
Venue	PVSC-31 IEEE
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/16/2005
Title	THE EFFECT OF MO DEPOSITION CONDITIONS ON DEFECT FORMATION AND DEVICE PERFORMANCE FOR CIGS SOLAR CELLS
Link	(MS Word 63 KB)
Authors	V. Mohanakrishnaswamy, et al.
Description	We have studied the effect of native defects on CIGS solar cells on an ongoing basis and recently investigated the role of Na. We modulated access of Na to the growing film by use of Si3N4 blocking layers as well as by varying the Mo thickness and density. Our process is tuned to the level of Na coming from our soda lime glass substrates, however, the role of Na is complex. Collectively the results suggest that one role of Na is that of a catalytic agent for the oxidation of VSe, which is a donor-like defect, to acceptor-like OSe. In simulating the effect of this defect in AMPS we find that its biggest effect on performance is its presence in the junction interface region, and its presence there gives rise to the Jsc ? Voc trade-off that we observe in our experimental data. This results in the efficiency being pinned in the 13 ? 14% range for our deposition process and explains the difficulties we have had in overcoming this mechanism. These insights also indicate the path to overcoming this performance limitation.
Venue	IEEE
Source	University of South Florida, Tampa
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/11/2005
Title	LIFE CYCLE ASSESSMENT OF PHOTOVOLTAICS: PERCEPTIONS, NEEDS, AND CHALLENGES
Link	(PDF 222 KB) Download Acrobat Reader.
Authors	E. A. Alsema, M. J. De Wild-Scholten, V. Fthenakis
Description	High impact publications recently depicted PV technologies as having higher external environmental costs than those of nuclear energy and natural-gas-fueled power plants. These assessments are based on old data and unbalanced assumptions, and they illustrate the need for LCA data describing the continuously improving photovoltaic systems and the inclusion of social benefits in this comparison.
Venue	IEEE Photovoltaic Specialistis Conference, Jan. 3-7, 2005, Orlando, FL
Sources	Brookhaven National Laboratory; Energy Research Centre of the Netherlands; Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/15/2005
Title	EFFICIENCY LIMITATIONS FOR WIDE-BAND-GAP CHALCOPYRITE SOLAR CELLS
Link	(PDF 309 KB) Download Acrobat Reader.
Authors	M. Gloeckler, J. R. Sites
Description	Wide-band-gap chalcopyrite solar cells, most prominently Cu(In,Ga)Se₂ (CIGS) with high Ga content, have failed over the past years to achieve conversion efficiencies consistent with those achieved with lower-Ga CIGS. Starting from a simple baseline case of a ZnO/CdS/CIGS solar cell, numerical modeling tools were used to investigate the effects of bulk and interface recombination for a broad range of absorber band-gap energies assuming that the Ga/In ratio primarily affects the conduction band. The model predicts that even very small interface recombination velocities limit the open circuit voltage, when the conductionband offset between window and absorber layer is close to zero or is negative. This is the case for CdS/CIGS structures with absorber band gaps above 1.3 - 1.4 eV. The simulations further predict that surface phases or pinning of the Fermi level at the interface can inhibit interface recombination, and hence, lead to an improvement in cell efficiency. Conversion efficiency for all band-gap energies is calculated based on a generic window layer/absorber structure assuming that the band alignment can be arbitrarily chosen. The implication of this work is that although the record CIGS efficiencies have been achieved with CdS window layers, CdS may not be the best window layer for wide-band-gap chalcopyrite solar cells. Our results agree very well with the reported record efficiency for CdS/CuInSe₂, CdS/CdTe, CdS/CuGaSe₂, and CdS/Cu(In,Ga)Se₂.
Venue	EMRS
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	03/22/2005
Title	LBIC ANALYSIS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 1.1 MB)
Authors	T. J. Nagle, J. R. Sites
Description	Light-beam-induced-current (LBIC) measurements are providing a direct link between the spatial non-uniformities inherent in thin-film polycrystalline solar cells, such as CdTe and CIGS, and the overall performance of these cells. LBIC is uniquely equipped to produce quantitative maps of local quantum efficiency with relative ease. Spatial resolution of 1 ?m at 1-sun intensity, and return to the same area after other measurements, is routinely achieved. A wavelength range of 638 to 857 nm is available with diode lasers. The LBIC measurements demonstrate that several types of effects that alter cell performance can be traced to specific local-area features. Examples of such effects include defects related to edges, grids, or scribes, spatial variations in alloying, and local changes due to high-temperature stress.
Venue	IEEE PVSC-31
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/15/2005
Title	ADVANCEMENTS IN FLEXIBLE CIGS MODULE MANUFACTURING
Link	(PDF 1.4 MB) Download Acrobat Reader.
Authors	M. E. Beck, et al.
Description	Roll-to-roll (RTR) manufacturing of consistent photovoltaic (PV) material over 1000-ft long metal foil lots has been realized at Global Solar Energy (GSE). Development of robust sensors and in-situ, real-time process control strategies for all thin-film coating (TFC) steps has enabled Global Solar to achieve manufacturing yields above 90%. In turn, reliable processing conditions enable rapid progress using well-controlled experiments designed for device optimization. Average large-area cell efficiency now exceeds 10%. Efficiency and yield have also been increased at the module level through improved fabrication methods. Flexible modules attain a power-toweight ratio of 40W/kg and aperture area efficiencies exceeding 11%. Real-time and accelerated stress tests investigating product reliability are underway.
Venue	IEEE PVSC
Source	Global Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	03/03/2005
Title	ADVANCEMENTS IN FLEXIBLE CIGS MODULE MANUFACTURING
Link	(PDF 1.4 MB) Download Acrobat Reader.
Authors	M. E. Beck, et al.
Description	Roll-to-roll (RTR) manufacturing of consistent photovoltaic (PV) material over 1000-ft long metal foil lots has been realized at Global Solar Energy (GSE). Development of robust sensors and in-situ, real-time process control strategies for all thin-film coating (TFC) steps has enabled Global Solar to achieve manufacturing yields above 90%. In turn, reliable processing conditions enable rapid progress using well-controlled experiments designed for device optimization. Average large-area cell efficiency now exceeds 10%. Efficiency and yield have also been increased at the module level through improved fabrication methods. Flexible modules attain a power-toweight ratio of 40W/kg and aperture area efficiencies exceeding 11%. Real-time and accelerated stress tests investigating product reliability are underway.
Venue	IEEE
Source	Global Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2005

Post Date	02/15/2005
Title	ANALYTICAL RESULTS OF OUTPUT RESTRICTION DUE TO THE VOLTAGE INCREASING OF POWER DISTRIBUTION LINE IN GRID-CONNECTED CLUSTERED PV SYSTEMS
Link	(PDF 2.4 MB) Download Acrobat Reader.
Authors	Y. Ueda, et al.
Description	Output restriction to prevent over voltage of power distribution line is one of the concerns for grid-connected clustered PV systems. To investigate the behavior of clustered PV systems, "Demonstrative research on clustered PV systems" has being conducted from December, 2002 in Gunma, Japan. More than 200 residential PV systems are already installed in demonstrative research area. Operation point of array output is estimated using minutely averages of collected data. The method to quantify loss due to output restriction is developed in this study.
Venue	IEEE PVSC
Source	Tokyo University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	03/03/2005
Title	CIGS SOLAR MODULES
Link	(PDF 344 KB) Download Acrobat Reader.
Authors	M. Powalla, et al.
Description
Venue	IEEE
Sources	Wurth Solar; ZSW
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2005

Post Date	02/09/2005
Title	PHYSICAL MODES OF THIN-FILM PV DEGRADATION
Link	(PDF 267 KB) Download Acrobat Reader.
Authors	V. G. Karpov, et al.
Description	We discuss physical modes of degradation related to the small thickness and lack of crystallinity in thin-film PV. We discriminate between 1) uniform material degradation through defect generation, light-induced diffusion, and electro-migration; 2) nonuniform degradation through ohmic or non-ohmic shunts; 3) metal contact deterioration. The first can equally apply to bulk and thin-film PV. Two others are specific to thin-film PV.
Venue	IEEE
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/04/2005
Title	STUDY OF POTENTIAL COST REDUCTIONS RESULTING FROM SUPER-LARGE-SCALE MANUFACTURING OF PV MODULES
Link	(MS Word 112 KB)
Authors	R. Arya, M. Keshner
Description	Short version of multi-GW production report
Venue	NREL Solar Review
Source	Hewlett Packard
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	03/03/2005
Title	BAND GAP GRADING IN CU(IN,GA)SE2 SOLAR CELLS
Link	(PDF 187 KB) Download Acrobat Reader.
Authors	M. Gloeckler, J. R. Sites
Description	The quaternary system Cu(In,Ga)Se2 (CIGS) allows the band gap of the semiconductor to be adjusted over a range of 1.04 ? 1.67 eV. Using a non-uniform Ga/In ratio throughout the film thickness, additional fields can be built into p-type CIGSbased solar cells, and some researchers have asserted that these fields can enhance performance. The experimental evidence that grading improves device performance, however, has not been compelling, mostly because the addition of Ga itself improves device performance and hence a consistent separation of the grading benefit has not always been achieved. Numerical modeling tools are used in this contribution to show that (1) there can be a beneficial eect of grading, (2) in standard thickness CIGS cells the benefit is smaller than commonly believed, (3) there is also the strong possibility of reduced rather than of increased device performance, and (4) thin-absorber cells derive more substantial benefit.
Venue	Elsevier Science
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/22/2004

Post Date	03/03/2005
Title	INDIUM: SUPPLY, DEMAND & FLAT PANEL DISPLAYS
Link	(MS Word 1.0 MB)
Author	B. O'Neill
Description
Venue	Presented at Minor Metals 2004, London, June 2004
Source	AIM Specialty Materials
Document Type	Conference Papers (Word document)
Resource Date	09/2004

Post Date	02/09/2005
Title	NUMERICAL MODELING OF CIGS AND CDTE SOLAR CELLS: SETTING THE BASELINE
Link	(MS Word 669 KB)
Authors	M. Gloeckler, et al.
Description	Numerical modeling of polycrystalline thin-film solar cells is an important strategy to test the viability of proposed physical explanations and to predict the effect of physical changes on cell performance. In general, this must be done with only partial knowledge of input parameters. Nevertheless, for consistent comparisons between laboratories, it is extremely useful to have a common starting point, or baseline. We will discuss guidelines that should be considered assigning input parameters for numerical modeling. Consequently specific baseline parameters for CIGS and CdTe are proposed. The modeling results for these baseline cases are presented and it is discussed how the baseline cases serve to describe some of the most important complications that are often found in experimental CIGS and CdTe solar cells.
Venue	IEEE
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/07/2005
Title	TECHNOLOGY AND MARKET CHALLENGES TO MAINSTREAM THIN-FILM PHOTOVOLTAIC MODULES AND APPLICATIONS
Link	(PDF 276 KB) Download Acrobat Reader.
Author	R. Arya
Description	Technology and manufacturing advances over the past 25 years has led to widespread commercial use of thin film modules in many consumer applications. The three leading thin film solar module technologies are - amorphous silicon alloys (a-Si), copper indium diselenide alloys (CIGS), and cadmium telluride CdTe). These three technologies have demonstrated solar cells with efficiencies ~13% (a-Si), ~19% (CIGS), and ~16.5% (CdTe) respectively. Large area power modules are in various stages of initial production with these technologies and the module performance is in the 6%-11% range. Several manufacturing plants are in operation with plant capacities ranging from 3 MW to 30 MW. These plants are continuously increasing production with the present annual production of 1 MW to 5 MW. Technical challenges lie ahead in improving the module performance by reducing the gap between R&D cells and manufactured products so that they can successfully compete with crystalline silicon modules. Reliability of thin film modules in systems has been demonstrated with all three technologies with a fair degree of success. Several 1-480 kW grid-connected thin film module arrays are in deployment worldwide. Thin film modules are finding increasing acceptance for BIPV applications like roofs, facades, awnings etc. used in residential and commercial buildings. The cost of modules and market acceptance with new technologies still remains a major challenge to successful penetration of mainstream photovoltaic markets.
Venue
Source	N/A
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/17/2005
Title	DEVICE MODELING AND SIMULATION OF THE PERFORMANCE OF CU(IN_1-X,GA_X)SE₂
Link	(PDF 367 KB) Download Acrobat Reader.
Authors	J. Song, et al.
Description	Device modeling, thin Film solar cell; Cu(In,Ga)Se₂ (CIGS), graded band-gap, open-circuit voltage (V_oc), short-circuit current (I_sc)...
Venue
Source	University of Florida, Gainesville
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	03/03/2005
Title	THE SHELL SOLAR 245 KW GRID-CONNECTED CIS THIN FILM PV ROOFTOP ARRAY: SYSTEM DESIGN AND FIRST YEAR PERFORMANCE
Link	(PDF 123 KB) Download Acrobat Reader.
Authors	K. Mackamul, R. Wieting
Description	Shell Solar has deployed the world's largest rooftop thin film photovoltaic system, a 245-KW array consisting of 6144 ST40 modules using Shell's innovative copper indium diselenide-based (CIS) technology. Covering nearly 3,000 square meters on its module manufacturing building, the system is arranged in 13 rows wired into 256 module strings of 24 modules each, grid-connected through a 225KW Xantrex inverter. An innovative systems design approach was employed to evaluate a new modular commercial rooftop open-rack type array support structure. Utilizing low cost light gauge cold-formed steel sections, the design minimizes roof penetrations and enables modular design for simplified installation while creating a robust structure capable of withstanding 80 mph winds and zone 4 earthquake resistant. The system is designed for flat roofs (generally defined as pitch less than 2:12, or 2 inches in 12 feet). System design is optimized by analyzing the hourly and seasonal array output with the customer's utility rate schedule. Array tilt and azimuth angles are adjusted to provide the best value proposition to the customer. Additionally, the structure is utilized in a 245 kW CIS thin film installation with the savings and performance logged on a computer via internet.
Venue	IEEE
Source	Shell Solar Industries
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/14/2005
Title	CIGS J-V DISTORTION IN THE ABSENCE OF BLUE PHOTONS
Link	(MS Word 158 KB)
Authors	A. O. Pudov, et al.
Description	Common buffer materials used with CuInGaSe₂ (CIGS) absorbers produce conduction-band barriers that may significantly distort the current-voltage curves, especially when short-wavelength photons are excluded from the illumination spectrum. Earlier work documented this effect for CuInSe₂ (CIS) absorbers (band gap near 1.0 eV) with CdS buffers. Higher band-gap (~1.15 eV) CIGS absorbers show little or no distortion with CdS buffer layers. However, wider band-gap (lower electron affinity) ZnS(O,OH) or InS(O,OH) buffers, prepared by chemical-bath deposition, clearly show the J-V distortion. The distortions have a turn-on time constant the order of a minute and turn-off time constant the order of a day, and they correlate with major variations in apparent quantum efficiency measured with varying intensity and spectral content of bias light. The results are consistent with a conduction-band spike barrier that increases with buffer band gap and is larger when the electron concentration in the buffer is small.
Venue	EMRS
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/07/2005
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAIC TECHNOLOGIES: PROGRESS AND TECHNICAL ISSUES
Link	(PDF 370 KB) Download Acrobat Reader.
Author	H. S. Ullal
Description	Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for a thin-film CIGS solar cell and 16.5% for thin-film CdTe solar cell. A number of technical R&D issues related to CIS and CdTe have been identified. Thin-film power module efficiencies up to 13.4% has been achieved thus far. Tremendous progress has been made in the technology development for module fabrication, and multi-megawatt manufacturing facilities are coming on line with expansion plans in the next few years. Several 40-480 kW polycrystalline thin-film, grid-connected PV arrays have been deployed worldwide. Hot and humid testing is also under way to validate the long-term reliability of these emerging thin-film power products. The U.S. thin-film production (amorphous silicon [a-Si], CIS, CdTe) is expected to exceed 50 MW by the end of 2005.
Venue	PVSEC 19
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	03/03/2005
Title	TOWARDS THE DEVELOPMENT OF FLEXIBLE CIGS SOLAR CELLS ON POLYMER FILMS WITH EFFICIENCY EXCEEDING 15%
Link	(PDF 1.1 MB) Download Acrobat Reader.
Authors	D. Bremaud, et al.
Description	Development of Cu(In,Ga)Se2 (called CIGS) solar cells on polymers is challenging because of the thermo-physical properties of layers and substrates. CIGS layers of suitable structural and opto-electronic properties should be grown at low temperature (< 500ºC) as polyimides tend to degrade at higher deposition temperatures. Additionally, a method for controlled incorporation of an optimum amount of Na in CIGS is needed for highefficiency cells since polyimides do not contain Na. Solar cells were developed on commercially available Upilex foils. CIGS layers were grown by evaporation of elemental Cu, In, Ga and Se at different substrate temperatures. Na from a NaF film was incorporated into CIGS layers with a post-deposition diffusion method that is suitable for in-line production of solar cells. Independent measurements have confirmed 14.1% efficiency under simulated AM1.5 standard test conditions. This is the highest efficiency reported to date for any kind of solar cell grown on polymer films. An average reflectance loss of about 13% was measured for these cells. Application of a commonly used antireflection coating would enable more than 15% efficiency flexible CIGS solar cells on polyimide foils.
Venue
Source	Swiss Federal Institute of Technology
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/16/2005
Title	EFFECT OF MAXIMUM CU RATIO DURING THREE-STAGE CIGS GROWTH DOCUMENTED BY DESIGN OF EXPERIMENT
Link	(PDF 248 KB) Download Acrobat Reader.
Authors	M. E. Beck, J. S. Britt, D. C. Fisher, I. L. Repins
Description	The impact of a Cu-rich growth period during threestage CIGS co-evaporation on device performance was examined. Design of experiments was utilized to determine effect magnitudes and statistical significance. It was found that a Cu-rich growth period yields a statistically significant benefit for device performance. By varying film thickness, the number of moles deposited in stage 3 was also included as a variable. The latter did not produce a significant effect on efficiency. Comparison of these conclusions to other studies, and the application to manufacturing, are also discussed.
Venue
Sources	Global Solar; ITN Energy Systems
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/04/2005
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAIC TECHNOLOGIES: PROGRESS AND TECHNICAL ISSUES
Link	(MS Word 1.5 MB)
Author	H. S. Ullal
Description	Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for a thin-film CIGS solar cell and 16.5% for thin-film CdTe solar cell. A number of technical R&D issues related to CIS and CdTe have been identified. Thin-film power module efficiencies up to 13.4% has been achieved thus far. Tremendous progress has been made in the technology development for module fabrication, and multi-megawatt manufacturing facilities are coming on line with expansion plans in the next few years. Several 40-480 kW polycrystalline thin-film, grid-connected PV arrays have been deployed worldwide. Hot and humid testing is also under way to validate the long-term reliability of these emerging thin-film power products. The U.S. thin-film production (amorphous silicon [a-Si], CIS, CdTe) is expected to exceed 50 MW by the end of 2005.
Venue	PVSEC
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/09/2005
Title	THE MESOSCALE PHYSICS OF LARGE-AREA PHOTOVOLTAICS
Link	(PDF 252 KB) Download Acrobat Reader.
Authors	V. G. Karpov, et al.
Description	Recent findings make the physics of large-area thin-film devices a distinctive field of its own, considerably different from that of microelectronics. We show that (i) large-area thin-film photovoltaic (PV) devices are intrinsically nonuniform in the lateral directions, (ii) the nonuniformity spans over microscopically large dimensions, which can vary dramatically (from microns to meters) depending on light intensity and bias, and (iii) the nonuniformity significantly impacts the device performance and stability. Our understanding suggests the concept of interfacial layer that blocks the nonuniformity effects and can be applied photo-electrochemically. This concept is experimentally verified.
Venue	29th IEEE Osaka
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/16/2003

Post Date	02/17/2005
Title	EXPLANATION OF LIGHT/DARK SUPERPOSITION FAILURE IN CIGS SOLAR CELLS
Link	(MS Word 445 KB)
Authors	M. Gloeckler, C. Jenkins, J. R. Sites
Description	CIGS solar cells in many cases show a failure of light/dark superposition of their current-voltage (J-V) curves. Such failure generally becomes more pronounced at lower temperatures. J-V measurements under red light may also show an additional distortion, known historically as the "red kink". The proposed explanation is that a secondary barrier results from the conduction band offset between CIGS and the commonly employed CdS window layer. This barrier produces a second diode with the same polarity and in series with the primary photodiode. The secondary-diode barrier height is modified by photoinduced changes of trap occupancy in the CdS layer, hence creating a voltage shift between dark and light conditions. Numerical modeling of the proposed explanation, including a band offset consistent with experimental and theoretical values, gives a very good fit to measured light and dark J-V curves over a wide temperature range. It also predicts the observed difference between illuminated J-V curves with photon energy above the CdS band gap, and those with sub-band-gap illumination...
Venue	MRS, Spring 2003
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	04/2003

Post Date	02/07/2005
Title	PROGRESS IN U.S. PHOTOVOLTAICS: LOOKING BACK 30 YEARS AND LOOKING AHEAD 20
Link	(PDF 310 KB) Download Acrobat Reader.
Author	T. Surek
Description	Technology and learning curve analysis of R&D.
Venue	Osaka IEEE
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/07/2005
Title	PRACTICAL DOPING PRINCIPLES
Link	(PDF 270 KB) Download Acrobat Reader.
Author	A. Zunger
Description	Doping compound semiconductors.
Venue	NREL DOE Solar Program Review Meeting 2003
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/16/2005
Title	CUIN_XGA_1-XSE₂- THIN FILM SOLAR CELLS USING TRANSPARENT CONDUCTING OXIDE BACK CONTACTS FOR BIFACIAL AND TANDEM SOLAR CELLS
Link	(PDF 336 KB) Download Acrobat Reader.
Author	T. Nakada
Description
Venue	WCPEC-3
Source	Aoyama Gakuin University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/02/2005
Title	COMPARISON OF ENERGY PRODUCTION AND PERFORMANCE FROM FLAT-PLATE PHOTOVOLTAIC MODULE TECHNOLOGIES DEPLOYED AT FIXED TILT
Link	(PDF 206 KB) Download Acrobat Reader.
Author	J. A. del Cueto
Description	energy rating by technology
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	03/03/2005
Title	HIGH YIELD CIS PRODUCTION - PROGRESS & PERSPECTIVES
Link	(PDF 283 KB) Download Acrobat Reader.
Authors	R. Gay, D. E. Tarrant
Description	Outstanding progress has been made in the scale-up of high performance CIS thin film solar electric modules. Cumulative production for 2002 exceeded 1 MW; about twice the production rate for 2001. Line yield has increased from about 60% in 2000 to about 85% in 2002. Electrical performance has proven to be predictable with aperture efficiencies over 10%. These major accomplishment supports attractive cost projections for CIS. This paper will discuss Shell Solar Industries's (SSI's) status and plans for commercialization of CISbased thin-film PV with emphasis on line yield and will present an example of how barcode scribing has improved both productivity and yield.
Venue	NCPV and Solar Program Review Meeting 2003 NREL/CD-520-33586 Page 513
Source	Shell Solar Industries
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	03/03/2005
Title	CIS THIN FILM MANUFACTURING AT SHELL SOLAR: PRACTICAL TECHNIQUES IN VOLUME MANUFACTURING
Link	(PDF 1.6 MB) Download Acrobat Reader.
Authors	R. Wieting, et al.
Description	CIS technologies have emerged from the laboratory. Hand crafted construction of a few small devices has given way to practical methods essential to the continuous manufacturing of large modules in high volumes. This paper surveys the present status of CIS production technology as employed at Shell Solar and reviews in detail a number of the methods developed during the transition to volume manufacturing.
Venue	module making
Source	Shell Solar Industries
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/15/2005
Title	NON-VACUUM PROCESSING OF CIGS SOLAR CELLS ON FLEXIBLE POLYMERIC SUBSTRATES
Link	(PDF 186 KB) Download Acrobat Reader.
Authors	V. K. Kapur, et al.
Description	Using an ink based non-vacuum process CIGS solar cells were successfully fabricated on a flexible polymeric 'Upilex' substrate. A thin foil (0.001") of 'Upilex' was metallized by sputter deposition of 0.4 �m thick layer of Mo and CIGS solar cells were fabricated on it. 'Upilex' foil along with various device layers on it, withstood the fabrication conditions of ISET's process in which the maximum temperature was raised to 500°C.
Venue	WCPEC Japan
Source	ISET
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/16/2005
Title	THE EFFECT OF MO MORPHOLOGY ON THE PERFORMANCE OF CU(IN,GA)SE₂ THIN FILMS
Link	(PDF 1.5 MB) Download Acrobat Reader.
Authors	D. C. Fisher, et al.
Description	The properties of sputtered and electron-beam evaporated Mo are compared, and the resulting impacts on performance of co-evaporated CIGS devices deposited on each type of back contact are investigated. In past studies, the effect of Mo on Cu(In,Ga)Se₂device efficiency has been attributed largely to control of sodium diffusion from the glass. To verify this hypothesis, sodium-free Al₂O₃ substrates were utilized. Despite lack of Na in the substrate ? Na was provided as NaF on the Mo layer ? significant differences in device performance between the two types of Mo were observed. Purely resistive effects are ruled out by sheet resistance measurements, and comparison of current-voltage parameters. Negative contributions due to diffusion of harmful impurities from the substrate can be eliminated based on secondary ion mass spectroscopy results. These findings lead to the deduction of device performance dependency on Mo morphology.
Venue
Sources	Global Solar; ITN Energy Systems; National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/09/2005
Title	MICRONONUNIFORMITY EFFECTS IN THIN-FILM PHOTOVOLTAICS
Link	(PDF 350 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov, D. Shvydka
Description	We discuss effects of micrononuniformities on thin-film photovoltaics. The key factors are the device large area and the presence of potential barriers. We model the nonuniformity effects in the terms of random microdiodes connected in parallel through a resistive electrode. The microdiodes of low open circuit voltages affect macroscopically large regions. They strongly reduce the device performance and induce its nonuniform degradation in several different modes. We support our predictions by experiments.
Venue	2002 IEEE PVSC
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2002

Post Date	02/07/2005
Title	PV SOLAR ELECTRICITY: ONE AMONG THE NEW MILLENNIUM INDUSTRIES
Link	(PDF 6.0 MB) Download Acrobat Reader.
Author	W. Hoffmann
Description	ABSTRACT: During recent years, solar electricity generation based on photovoltaics has developed into an industry at annual growth rates above 20%. Major market segments served by this industry comprise consumer applications, remote industrial systems, developing countries, and grid-connected systems. The potential in these markets supports sustained future growth, particularly for applications in developing countries and gridconnected systems in the industrial countries, where PV-generated electricity eventually will start to compete with peak grid power. Backed by price experience curves and a laboratory proven technology road map, a module turnover representing 100 billion worlwide can be extrapolated. A sustainable energy contribution to the worldwide energy mix in subsequent decades is foreseen as a result of competitive PV solar electricity applications. Keywords: PV Market Growth ? 1: Strategy ? 2: Cost Reduction ? 3
Venue	17th European Photovoltaic Solar Energy Conference, Munich, Germany, 22-26 October 2001
Source	RWE Schott
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2001

Post Date	02/14/2005
Title	ZNO/ZNS(O,OH)/CU(IN,GA)SE2/MO SOLAR CELL WITH 18.6% EFFICIENCY
Link	(MS Word 482 KB)
Authors	M. A. Contreras, et al.
Description	We report on recent enhancements to device performance leading to a certified total-area energy conversion efficiency of 18.6% for Cu(In,Ga)Se2 solar cells that incorporate a ZnS(O,OH) buffer layer as an alternative to CdS. Along with information on device fabrication and layer properties, we provide a comparative device analysis between this type of solar cell and the slightly more efficient ZnO/CdS/Cu(In,Ga)Se2/Mo solar cell structure. This comparative study allows us to elucidate the areas for optimization in the quest for conversion efficiency above 20% in thin-film polycrystalline solar cells. It quantifies the gains in current generation due to superior collection at short wavelengths, as well as the somewhat lower voltage and infrared response.
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	2000

Post Date	02/14/2005
Title	ZNO/ZNS(O,OH)/CU(IN,GA)SE2/MO SOLAR CELL WITH 18.6% EFFICIENCY
Link	(MS Word 482 KB)
Author	M. A. Contreras
Description	We report on recent enhancements to device performance leading to a certified total-area energy conversion efficiency of 18.6% for Cu(In,Ga)Se2 solar cells that incorporate a ZnS(O,OH) buffer layer as an alternative to CdS. Along with information on device fabrication and layer properties, we provide a comparative device analysis between this type of solar cell and the slightly more efficient ZnO/CdS/Cu(In,Ga)Se2/Mo solar cell structure. This comparative study allows us to elucidate the areas for optimization in the quest for conversion efficiency above 20% in thin-film polycrystalline solar cells. It quantifies the gains in current generation due to superior collection at short wavelengths, as well as the somewhat lower voltage and infrared response.
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	2000

Post Date	02/11/2005
Title	HEALTH, SAFETY AND ENVIRONMENTAL ISSUES IN THIN FILM MANUFACTURING
Link	(PDF 50 KB) Download Acrobat Reader.
Authors	E. A. Alsema, et al.
Description	An investigation is made of Health, Safety and Environmental (HSE) aspects for the manufacturing, use and decommissioning of CdTe, CIS and a-Si modules. Issues regarding energy requirements, resource availability, emissions of toxic materials, occupational health and safety and module waste treatment are reviewed. Waste streams in thin film module manufacturing are analyzed in detail and treatment methods are discussed. Finally the technological options for thin film module recycling are investigated. It is concluded that there are no serious HSE bottlenecks for upscaling to production levels of 500 MWp/yr and that adequate methods are available for treatment of the manufacturing wastes. However, on the longer term issues regarding CdTe and CIS module waste treatment, In and Te resource availibility and module recycling need to adressed. Appropriate recycling methods for CdTe and CIS modules do not exist at present but the problem is being adressed by the PV industry.
Venue
Source	Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2000

Presentations

Post Date	05/18/2006
Title	HIGH EFFICIENCY CDTE AND CIGS
Link	(PowerPoint 28.8 MB)
Author	R. Noufi
Description	Highlights and challenges
Venue	WCPEC4 oral
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/2006

Post Date	04/19/2006
Title	THIN CU(INGA)SE2
Link	(PDF 2.2 MB) Download Acrobat Reader.
Author	W. N. Shafarman
Description	A. Introduction B. Review experimental results in literature C. IEC results: compare etched and thin deposited films D. Back contact E. Light trapping
Venue	CIS National R&D Team meeting
Source	University of Delaware
Document Type	Presentation (Adobe Postscript file)
Resource Date	04/2006

Post Date	06/13/2006
Title	CDTE NATIONAL R&D TEAM MEETING 2006
Link	(PDF 17.3 MB) Download Acrobat Reader.
Author	H. S. Ullal
Description	The presentations from the National R&D Team meeting and Voc Workshop; Large file!
Venue	National R&D Team meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	03/2006

Post Date	11/11/2005
Title	THIN FILM PV PARTNERSHIP PROGRAM 2005
Link	(PowerPoint 10.8 MB)
Author	K. Zweibel
Description	Overview of the purpose, strategies, and goals of the Thin Film Partnership Program, including updated module, BOS, and system cost projections for 2005 and 2020.
Venue	2005 DOE Solar Review
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/10/2005

Post Date	11/11/2005
Title	HIGH EFFICIENCY CIGS THIN FILM CELLS
Link	(PowerPoint 2.3 MB)
Author	K. Ramanathan
Description	thinner CIGS; less pure feedstock indium; 17.1% 1-micron cell;
Venue	2005 DOE Solar Review
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/11/2005
Title	UNDERSTANDING THE PHYSICS OF CDS PV
Link	(PowerPoint 3.2 MB)
Author	V. G. Karpov
Description	piezo electric effect discussed
Venue	2005 DOE Solar Review
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/11/2005
Title	PROCESS TOLERANCES IN ROLL-TO-ROLL MANUFACTURING OF CIGS ON FLEXIBLE SUBSTRATES
Link	(PowerPoint 16.4 MB)
Author	M. E. Beck
Description	Global Solar manufacturing experience and optimization
Venue	DOE Solar Review Meeting 2005
Source	Global Solar Energy
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/18/2005
Title	HOT AND HUMID THIN FILM MODULE TESTING IN FLORIDA
Link	(JPG 1.2 MB)
Author	N. G. Dhere
Description	various arrays are tested
Venue	DOE Solar Review 2005 poster
Source	FLorida Solar Energy Center
Document Type	Presentation (JPG image)
Resource Date	11/2005

Post Date	11/23/2005
Title	NANOSCALE-DESIGNED CERAMIC FILMS
Link	(PDF 1.9 MB) Download Acrobat Reader.
Author	S. Sambasivan
Description	thermal barriers, conformal alumina films, epitaxial oxide growth
Venue	Nanocommerce 2004, Chicago
Source	Applied thin films
Document Type	Presentation (Adobe Postscript file)
Resource Date	10/2005

Post Date	09/02/2005
Title	PV PAST THE TIPPING POINT
Link	(PowerPoint 31.8 MB)
Author	K. Zweibel
Description	Photovoltaics is growing rapidly, coming down in cost, and technical progress is substantial. We can be assured that PV costs will come down enough to provide electricity at an energy signifiant level.
Venue	Presntation at NREL to Norwegian StudyTour sponsored by CSM August 31, 2005
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	08/31/2005

Post Date	07/28/2005
Title	2002 TO 2005 THIN FILM PARTNERSHIP BUDGET TRENDS
Link	(PowerPoint 38 KB)
Author	K. Zweibel
Description	Budget in thin films for subcontracts is down 36% since 2002.
Venue
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	07/2005

Post Date	03/17/2005
Title	ALTERNATIVE JUNCTION SUBTEAM
Link	(PowerPoint 851 KB)
Author	J. R. Sites
Description	comparing different junction partners and absorber band gaps
Venue	CIS National R&D Team Meeting March 2005 NREL
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	03/08/2005

Post Date	02/09/2005
Title	LARGE AREA THIN FILM DEVICES: NONUNIFORMITIES, INTERFACIAL LAYESR, REACG-THROUGH EFFECTS
Link	(PowerPoint 884 KB)
Author	V. G. Karpov
Description
Venue	DOE Solar Review
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/2004

Post Date	02/07/2005
Title	THIN FILMS AND THE SYSTEM DRIVEN APPROACH
Link	(PowerPoint 1.0 MB)
Author	K. Zweibel
Description	Cost analysis of thin films for semiconductor, encapusulation, layer thickness, and efficiency.
Venue	DOE and NREL Solar Review Meeting 2004
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/2004

Post Date	02/07/2005
Title	2ND GENERATION THIN FILMS
Link	(PowerPoint 8.9 MB)
Author	K. Zweibel
Description	Potential of CIS, CdTe, and a-Si thin films.
Venue	Rice University Solar Energy Workshop
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	09/2004

Post Date	04/22/2005
Title	MOISTURE INGRESS PROTECTION BY COMBINED BACKSHEET AND ENCAPSULANT CONSTRUCTIONS
Link	(PDF 1.7 MB) Download Acrobat Reader.
Authors	G. J. Jorgensen, M. Kempe, C. Kennedy, K. Terwilliger
Description	WVTR, PET, EVA, BRP, TruSeal
Venue	Thin Film Module Reliability National Team Meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	LEAKAGE CURRENTS AND HIGH-VOLTAGE THIN FILM MODULES
Link	(PDF 1.1 MB) Download Acrobat Reader.
Author	N. G. Dhere
Description	FSEC testing of outdoor thin film arrays
Venue	Thin Film Module Reliability Team Meeting
Source	FLorida Solar Energy Center
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	EFFECTS OF MOISTURE INGRESS ON PV MODULES
Link	(PDF 528 KB) Download Acrobat Reader.
Author	M. Kempe
Description	Measuring the rate water vapor moves through EVA from the edge and the back
Venue	Thin Film Module Reliability National Team Meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	PAST AND PREDICTED THIN FILM MODULE PRODUCTION IN THE US BY TECHNOLOGY
Link	(PowerPoint 45 KB)
Author	K. Zweibel
Description	Annual MWp/yr 2000-2011 by technology
Venue
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/22/2004

Post Date	02/11/2005
Title	PV MODULE RECYCLING IN THE US
Link	(PowerPoint 3.8 MB)
Authors	V. Fthenakis, K. Zweibel
Description	Recycling today and tomorrow.
Venue	EU Workshop "Waste Challenge"
Sources	Brookhaven National Laboratory; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	03/2004

Post Date	02/11/2005
Title	PV MODULE RECYCLING IN THE US
Link	(PDF 600 KB) Download Acrobat Reader.
Authors	V. Fthenakis, K. Zweibel
Description	Recycling today and tomorrow
Venue	EIA Workshop
Source	N/A
Document Type	Presentation (Adobe Postscript file)
Resource Date	03/2004

Post Date	02/07/2005
Title	PV AS A MAJOR SOURCE OF GLOBAL ELECTRICITY
Link	(PowerPoint 13.2 MB)
Author	K. Zweibel
Description	Projected improvements needs to make PV a major source of electricity.
Venue	University of Toledo
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	02/24/2004

Post Date	02/17/2005
Title	A COMPARISON OF THIN FILMS AND X-SI IN THE US MARKET, HISTORICAL AND PROJECTED
Link	(MS Word 31 KB)
Author	K. Zweibel
Description	Thin films are gaining ground on x-Si and are projected to overtake it in the US about 2010-2011.
Venue	Thin Film Partnership and Paul Maycock's PV News February 2005
Source	PV News
Document Type	Presentation (Word document)
Resource Date	02/17/2004

Post Date	03/03/2005
Title	BARRIER COATINGGS FOR CIS CELLS
Link	(PowerPoint 45 KB)
Author	L. Olsen
Description	Shell cells and humidity
Venue
Source	Pacific Northwest National Lab (PNNL)
Document Type	Presentation (Powerpoint presentation)
Resource Date	2004

Post Date	03/03/2005
Title	RECENT CIGS CELL DATA AT NREL 2004
Link	(PowerPoint 719 KB)
Author	K. Ramanathan
Description
Venue	European MRS
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2004

Post Date	02/15/2005
Title	THE INTRINSIC STABILITY OF POLYCRYSTALLINE THIN FILM SOLAR CELLS
Link	(PowerPoint 3.0 MB)
Authors	D. Albin, T. Berniard, S. Demetsu, T. J. McMahon, R. Noufi
Description	Indoor, accelerated tests of thin film CIS and CdTe
Venue
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2004

Post Date	02/07/2005
Title	PROGRESS IN US PV
Link	(PowerPoint 1.5 MB)
Author	T. Surek
Description	50 years of progress in PV.
Venue	Osaka IEEE conference
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2003

Post Date	03/04/2005
Title	BARRIER COATINGS AND EFFECTS OF MOISTURE SSI CIGSS CELLS
Link	(PowerPoint 1.7 MB)
Author	L. Olsen
Description
Venue	reliability meeting
Source	Pacific Northwest National Lab (PNNL)
Document Type	Presentation (Powerpoint presentation)
Resource Date	2003

Post Date	03/04/2005
Title	PROCESS CONTROL ENHANCEMENTS FOR FLEXIBLE CIGS MODULE MANUFACTURING
Link	(PowerPoint 21.0 MB)
Author	N/A
Description
Venue	2003 NCPV meeting
Source	Global Solar
Document Type	Presentation (Powerpoint presentation)
Resource Date	2003

Annual/Final Reports

Post Date	10/05/2009
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THE THIN FILM SOLAR CELL INTERFACES
Link	(PDF 2.1 MB) Download Acrobat Reader.
Author	C. Heske
Description	This project was devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin-film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission), a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focused on the following: (1) deriving the benchmark picture for world-record cells, (2) analyzing state-of-the-art cells from industrial processes, and (3) troubleshooting of cells with substandard performance.
Venue	University Nevada, Las Vegas, subcontract XXL-44205-12, Final Report
Source	University of Nevada, Las Vegas
Document Type	Annual Report (Adobe Postscript file)
Resource Date	09/2009

Post Date	04/22/2009
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
Link	(PDF 571 KB) Download Acrobat Reader.
Author	N. G. Dhere
Description	During this project CuIn1-xGaxSe2-ySy (CIGSeS)/CdS thin-film solar cells were prepared on molybdenum-coated soda lime glass substrates. Low-toxicity selenium precursors, diethylselenium (DESe) or other organometallic precursors, were used for selenization of metallic precursors. Rapid thermal processing (RTP) was developed as an alternative to conventional selenization and sulfurization to reduce the process time and thermal budget, thus enhancing throughput. CuIn1-xGaxS2 (CIGS2) thin-film solar cells were also developed. As easily scaleable magnetron sputtering technique was used for deposition of back contact, metallic precursors, and transparent and conducting oxides. Compact, large-grain, 0.9-2.75-?m-thick absorber layers were prepared by selenization/sulfurization of elemental precursors at 475�-515�C in diluted DESe or other organometallic precursors and diluted H2S. Experiments were performed to reduce absorber thickness so as to minimize the indium consumption using both conventional, as well as the RTP, approach. Experiments were carried out on thinner (i.e., 1.2 - 1.5 ?m) CIGS2 absorbers. The effect of sodium addition on copper-poor CIGS2 absorbers and thin-film solar cells was studied. Alternate heterojunction partner layers were developed for CIGS2 thin-film solar cells.
Venue	Florida Solar Energy Center (FSEC), subcontract XXL-5-44205-08, Final Report
Source	FLorida Solar Energy Center
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/2009

Post Date	07/09/2008
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 4.2 MB) Download Acrobat Reader.
Authors	R. W. Birkmire, W. N. Shafarman, E. Eser, S. S. Hegedus, B. E. McCandless, K. D. Dobson, S. Bowden
Description	This report describes results achieved during phase V of a V-phase subcontract to develop and understand thin film solar cell technology associated to CuInSe2 and related alloys, a-Si and its alloys and CdTe. This includes application of a-Si to c-Si wafer-type cells as well. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: 1) quantitative analysis of processing steps to provide information for efficient commercial scale equipment design and operation; 2) device characterization relating the device performance to materials properties and process conditions; 3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; 4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and 5) evaluation of cell stability with respect to illumination, temperature and ambient and with respect to device structure and module encapsulation.
Venue	Institute of Energy Conversion (U. Delaware), Subcontract No. ADJ-1-30630-12, annual report
Source	University of Delaware
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/01/2008

Post Date	10/25/2007
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 1.3 MB) Download Acrobat Reader.
Authors	C. Heske, M. Baer
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In the last year, we could draw a complete picture of the chemical and electronic properties of the deeply buried chalcopyrite/back contact interface. For these experiments Cu(In,Ga)Se2 ("CIGSe") and Cu(In,Ga)(S,Se)2 ("CIGSSe")/back contact samples pre-pared by the group of W. Shafarman (Institute of Energy Conversion, University of Delaware) were used. We have found a pronounced chemical interaction between absorber and back contact, namely the formation of MoSe2 (and Mo(S,Se)2) and a "diffusion" of Ga into the Mo layer. In addition, we could derive a tentatively flat valence band alignment at this interface. In addition, we have investigated the CdS/CIGSe interface of samples provided by the National Renewable Energy Laboratory (M. Contreras, R. Noufi), which currently holds the world record for respective solar cell devices in terms of photovoltaic performance. Our results show that, in contrast to earlier measurements on samples from a different source, no pronounced S/Se intermixing at this interface can be observed.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, annual report
Source	University of Nevada, Las Vegas
Document Type	Annual Report (Adobe Postscript file)
Resource Date	08/15/2007

Post Date	10/11/2007
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
Link	(PDF 982 KB) Download Acrobat Reader.
Author	J. D. Cohen
Description	We have worked to characterize the electronic properties of nc-Si:H materials obtained from United Solar. An extensive set of of new sample devices were obtained, all of which were actual working n-i-p solar cell devices. These were all deposited on specular stainless-steel under four different types of hydrogen profiling, and each deposition contained samples with varying degrees of crystalline fractions. Our data suggested that the degree of crystallinity in these nc-Si:H samples, rather than the hydrogen profiling function itself, was the strongest factor determining the defect response in our junction capacitance measurements. We also found that the samples that contained a higher fraction of amorphous component, as determined from Raman spectroscopy, exhibited the highest resilience to light-induced deep defect creation indicating an actual slight decrease in defect response as shown by DLCP measurements. This agrees with our measurements reported last year. On the other hand, the samples with estimated crystalline fractions above 60vol.% exhibited quite a pronounced increase of deep defects after light soakIn spite of this, all of the sample devices exhibited a decrease in performance after light soaking with 610nm filtered ELH light. Further studies are being pursued to test a degradation model over the wider range of nc-Si:H samples received during this past year. We have been studying in detail the set HWCVD a-Si,Ge:H alloys deposited at NREL by Yueqin Xu in which controlled levels of oxygen impurities were introduced, ranging from below 1019cm-3 to roughly 5 � 1020cm-3. This past year we discovered that the oxygen was responsible for a distinct deep defect, with an optical transition lying roughly 1.3 to 1.4 eV above the valence band. We hypothesize that the observed oxygen impurity related defect state may be associated with a positively charged oxygen donor level, possibly the previously suggested three fold coordinated oxygen center (O3+). Moreover, because the electrons excited into this defect remain trapped for roughly 0.5s at temperatures up to 370K, this strongly implies that there must exist a large barrier to their subsequent thermal emission into the conduction band. Follow up studies will try to pin down the thermal emission energy of the electron into the conduction in order to construct a configurational coordinate diagram for the transitions involving this defect. Also, we will examine samples containing a wider range of Ge alloy fractions to ascertain whether Ge itself may be playing a central role in the appearance of this defect. We used our junction capacitance methods to study the effect of Na on CIGS thin film solar cells. Our DLCP measurements revealed an increased free carrier density with the addition of Na and an activated bulk defect in CIGS absorber. However, neither could account for the >40% increase in efficiency with the addition of Na. The sub-band-gap TPC spectra showed a broader defect band and a steeper Urbach energy with the addition of Na which implies an increase in the carrier mobilities, but this again was not expected to lead to differences in performance consistent with the observations. Ultimately, forward bias admittance measurements revealed the existence of a large defect density at the CdS/CIGS heterojunction for the lower Na sample. It is interesting to note that SIMS profiles showed the Na moving towards the front of the cell when it is intentionally added. Finally, we argued that such a defect could readily explain the loss in VOC in the sample with reduced Na, and would be consistent with the observed admittance and DLCP behavior for this sample. Thus, it appears that it is the passivation of these interfacial defects that primarily accounts for the beneficial effects of Na toward the increased performance of the CIGS solar cells fabricated at IEC.ing.
Venue	University of Oregon, subcontract ZXL-5-44205-11, annual report
Source	University of Oregon
Document Type	Annual Report (Adobe Postscript file)
Resource Date	08/2007

Post Date	08/01/2007
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
Link	(PDF 3.4 MB) Download Acrobat Reader.
Author	N. G. Dhere
Description	The research activities at theFSEC PV Materials Lab are focused on developing highly efficient thin-film solar cells capable of being produced using an economical process for achieving this goal. CuIn1-xGaxSe2-y(CIGSeS) is a potential candidate for this purpose. Sputtering is the technique capable of providing high yield and high production volume. Research activities presented here focuses on developing CIGSeS thin films by depositing elemental precursor Cu-In-Ga by magnetron sputtering technique followed by selenization/sulfurization in either conventional furnace or by rapid thermal processing. During the first year, experiments were carried out to optimize conditions for both conventional and rapid thermal processing approaches. Also experiments were conducted on very thin absorber layers with both the conventional and rapid thermal processing approaches. These initial experiments towards optimizing the selenization parameters were discussed in detail in earlier reports.
Venue	Florida Solar Energy Center (FSEC), U. Central Florida, subcontract XXL-5-44205-08, annual report
Source	FLorida Solar Energy Center
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/22/2007

Post Date	06/22/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 1.3 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The fundamental work on CIGS cells included an analysis of the expected behavior for submicron thin absorbers. A baseline scenario based on experimental results was compared with conditions where the absorber lifetime and its carrier concentration were reduced by an order of magnitude. Additional calculations compared front-side with back-side illumination, again in the context of experimental results, and calculated several consequences of weak-diode areas and partial shunting, both expected to be of increasing importance for thinner CIGS. Finally, a collaboration with NREL compared the differences between 19.5%-efficient CdZnS/CIGS cells and those made with the conventional CdS buffer. A major CdTe project in response to the excessive voltage deficit between CdTe and single-crystal cells has been the analysis of strategies to significantly enhance voltage. One strategy recommended for a major experimental effort is an n-i-p structure with an electron reflector before the back contact. Experimentally, CdTe lifetime and current-voltage curves were measured as a function of copper amount used in the back contact, and the expected impact of low lifetimes, including artificially large A-factors, was calculated. Also, experimentally, CdTe cells made with commercially compatible processing were utilized to determine how CdS thickness affects the cell performance parameters.
Venue	Colorado State University subcontract XXL-5-44205-03, Phase II Annual report
Source	Colorado State University
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/30/2007

Post Date	09/07/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN-FILM SOLAR CELL INTERFACES
Link	(PDF 415 KB) Download Acrobat Reader.
Authors	M. Baer, C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spec-troscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. First funds for this project became available in the middle of July 2005. Since then, the workforce of the group was expanded to the size required for this project. The experimental instrumentation at UNLV ? a four-chamber ultra-high vacuum surface analysis and modification system ? was commissioned and put to routine use after its re-location from the University of W�rzburg, Germany. In addition, a setup for inverse photoemission was integrated and a new electron analyzer was installed at UNLV to al-low state-of-the-art data acquisition and spectral quality. Contacts within the Thin Film PV Partnership Program were established to secure a supply of adequate samples. These samples were analyzed both in the lab at UNLV as well as in our beamtimes at the Advanced Light Source, Lawrence Berkeley National Laboratory (Nov. 2 ? 13, 2005 and May 16 ? 23, 2006). In our first beamtime within this project at the Advanced Light Source we could gather first results with Cu(In,Ga)Se2 samples prepared by NREL. Combined with addi-tional photoemission measurements at UNLV, a detailed picture of the chemical compo-sition at several interfaces and surface of the device structure could be drawn. Also dur-ing the first beamtime at the Advanced Light Source, we conducted first XES measure-ments of CdTe/CdS samples prepared by the group of A. Compaan (University of Toledo). Recently, these synchrotron results could be complemented by initial photo-emission measurements at UNLV of CdTe/CdS thin film stacks provided by X. Wu (NREL).
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, annual report
Source	University of Nevada, Las Vegas
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/15/2006

Post Date	08/17/2006
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
Link	(PDF 841 KB) Download Acrobat Reader.
Author	N. G. Dhere
Description	Excellent facilities have been developed at FSEC for the development of p type CIGSS thin films on large, 10 cm x 15 cm substrates [12[14]. CIGSeS thin films were prepared on glass in two steps. Step one involved the deposition of CuGa-In metallic precursors on molybdenum coated glass substrate using DC magnetron sputtering and step two involved the selenization/sulfurization of these metallic precursors either by using diluted diethylselenide (DESe) as a selenium source and diluted H2S as a sulfur source respectively, or by rapid thermal processing (RTP) using elemental selenium and diluted H2S as a sulfur source. Experiments were carried out to optimize Cu/In+Ga ratio, amount of NaF and the selenization/sulfurization temperature and time. The metallic precursors CuGa and In were deposited by DC magnetron sputtering technique. The Cu/In+Ga ratio was varied from ~ 0.7 ? 1.05. NaF of up to 12 nm was deposited after the deposition of metallic precursor by thermal evaporation. The selenization of the precursor was carried out at various temperatures raging from 400 �C to 525�C and time raging from 10 minutes to 85 minutes. The sulfurization temperature was carried out at the highest selenization temperature and the time varied from 10 min to 30 min. Comparative analysis between the etched and unetched absorber layers was also carried out. Performance of the cells was improved beyond 13% by selenization/sulfurization treatment and optimizing the i:ZnO thickness. The Voc improved from 495 mV to 540 mV. The highest efficiency of 13.73% was obtained and the corresponding electrical parameters were open circuit voltage, Voc =540 mV, short circuit current density, Jsc =38.37 mA/cm2 and fill factor, FF = 66.33%. The morphology of the films was studied by scanning electron microscopy. To the best of our knowledge the efficiency of 13.73% is the world record on small area cells prepared by selenization/sulfurization in conventional furnace.
Venue	Florida Solar Energy Center, subcontract XXL-5-44205-08, annual report
Source	FLorida Solar Energy Center
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/06/2006

Post Date	07/25/2006
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	Our work has focused on three areas of study. First, we used transient photocapacitance (TPC) spectroscopy, transient photocurrent (TPI) and drive-level capacitance profiling (DLCP) to characterize the electronic properties of hydrogenated nanocrystalline Si (nc-Si:H) within a set of working n-i-p solar cell devices produced at United Solar Ovonics Corporation. Because the nc-Si:H layers in these more recent samples appear to be somewhat more intrinsic than those studied previously, with electron carrier densities estimated to lie below 1015 cm-3, we were able to obtain a definite deep defect response in our DLCP measurements for some of the samples. Surprisingly, this defect signal was observed to decrease after light-soaking rather than increase. Second, we continued our studies of the lower filament temperature HWCVD a-Si,Ge:H alloys being developed at NREL. These samples have revealed very good electronic properties. However, some later samples were of definite poorer quality and this appeared to be a result of excess oxygen contamination. The source of this contamination was identified and eliminated in the Fall, 2005, and we were then able to obtain a series of samples for study with different levels of oxygen introduced in a controlled manner using a variable air-leak. Surprisingly, these samples did not show a deterioration of electronic properties as a result of increasing oxygen levels. Moreover, the samples with moderate levels of oxygen actually revealed smaller Urbach energies, to below 40meV in one case. We also began examining the kinetics of light-induced degradation and annealing in these samples. It appears that these kinetics are somewhat different than those obtained in high quality PECVD a-Si,Ge:H films. In particular, the metastable deep defects anneal away over a much narrower ranges of temperatures than the PECVD a-Si,Ge:H films, suggested a narrower range of energy barriers for metastable defect recovery. Third, we applied both admittance and DLCP measurements to a set of CIGS photovoltaic devices that were obtained from Miguel Contreras at NREL. We examined eight devices that varied in their level of performance, from about 14.4% to nearly 17.5% efficiency. Admittance measurements carried out at zero volts applied bias did not reveal significant differences among this set of films. In particular, they did not reveal any variations in the deep acceptor capacitance step that some studies have found to be an indicator of device efficiencies. However, the DLC profiles on this set of NREL samples did indicate major differences. In particular, the DLCP determined defect density obtained under forward bias conditions, probing the defects in the region closest to the barrier interface, appeared to be reasonably well correlated to the device efficiencies across this set of samples.
Venue	University of Oregon, subcontract ZXL-5-44205-11, Annual Report
Source	University of Oregon
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/05/2006

Post Date	05/18/2006
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 2.5 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	A number of studies relating to the fundamental operation of CIGS and CdTe solar cells were performed during Phase I. In addition, we have worked closely with industrial and NREL partners to evaluate specific cells, expanded our LBIC (light-beam-induced-current) capabilities, and analyzed the effective efficiency to be expected from several commercial thin-film modules. The fundamental work on CIGS cells included a detailed analysis of grain-boundary effects using two-dimensional modeling. It showed that the relatively benign effects observed are best explained by a decrease in the valence band edge in the vicinity of the grain boundary. A second project, which followed earlier work relating spatial grading of CIGS to performance, showed the increasing importance of an electron reflector at the back of the CIGS absorber as it is made progressively thinner. A third project generalized earlier work on the window/absorber conduction band offset to show that there is a general rule governing when a "spike" leads to a distortion of the current-voltage curve. The CdTe studies included a reasonably convincing explanation of the 1.456-eV photoluminescence peak as a copper-oxygen donor complex about 150 meV below the conduction-band minimum. A second project demonstrated how different combinations of absorber lifetime and back-contact barrier lead to different common features seen with CdTe cells. A third project extended stability and uniformity studies to focus on performance differences among cells with graphite, Ag, and Ni back contacts. Finally, a study of current response following voltage steps showed that reversible transients were essentially always present, but their magnitude varied considerably with sample preparation.
Venue	Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	06/02/2006
Title	DOE SOLAR ENERGY TECHNOLOGY PROGRAM FY2005 ANNUAL REPORT
Link	(PDF 5.2 MB) Download Acrobat Reader.
Author	N/A
Description	The majority of the Program?s budget is allocated to PV research and development (R&D). All PV devices convert sunlight directly into electricity. However, there is a variety of materials and processes for creating PV devices, each with its own benefits and drawbacks. The major trade-off is between cost and sunlight-to-electricity conversion efficiency?higher efficiency typically translates into higher cost. Program participants consistently achieve world-record efficiencies for different types of PV, but each effort has the same ultimate goal: optimizing cost and efficiency to produce the least expensive end-use electricity.
Venue	DOE/GO-102006-2314May 2006
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	04/10/2006
Title	FULFILLING THE PROMISE OF THIN FILM PV
Link	(PDF 5.5 MB) Download Acrobat Reader.
Author	K. Zweibel
Description	The Thin Film PV Partnership spearheads R&D on emerging thin film PV technologies. Led by the National Center for Photovoltaics and NREL, the Partnership leverages the combined efforts of the thin film PV industry, universities, and government research institutes.
Venue	Brochure excerpt
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/2006

Post Date	02/07/2006
Title	DOE FY2007 CONGRESSIONAL BUDGET REQUEST FOR ENERGY SUPPLY AND CONSERVATION
Link	(PDF 3.4 MB) Download Acrobat Reader.
Author	N/A
Description	Appropriation Account Summary..........................................................................................................3 Appropriation Language ........................................................................................................................7 Energy Efficiency and Renewable Energy ..........................................................................................11 Electricity Delivery & Energy Reliability .........................................................................................511 Nuclear Energy .................................................................................................................................571 Environment, Safety and Health ........................................................................................................705 Legacy Management.........................................................................................................................733
Venue	The Department of Energy?s FY 2007 Congressional Budget justification is available on the Office of Chief Financial Officer/CFO homepage at http://www.mbe.doe.gov/budget
Source	Department of Energy
Document Type	Annual Report (Adobe Postscript file)
Resource Date	02/2006

Post Date	04/11/2006
Title	TRANSPORT, INTERFACES, AND MODELING IN AMORPHOUS SILICON BASED SOLAR CELLS
Link	(MS Word 2.1 MB)
Author	E. A. Schiff
Description	In this report we present the status of three tasks of this research project: 1. Amorphous Silicon Solar Cell Characteristics and Modeling 2. Photocarrier Drift Mobility Measurements in a-Si:H and CIGS 3. Hole-Conducting Polymers as p-layer Materials for Amorphous and Crystal Silicon Solar Cells. In particular for the first project, we have published fairly extensively (see the references and the associated web-links at the end of this report. )
Venue	Syracuse University, Subcontract NDJ-2-30630-24 Annual Report
Source	Syracuse University
Document Type	Annual Report (Word document)
Resource Date	02/2006

Post Date	02/01/2006
Title	THIN FILM PV PARTNERSHIP
Link	(MS Word 393 KB)
Author	K. Zweibel
Description	Objectives Support the near-term transition to first-time manufacturing and commercial introduction of reliable thin-film a-Si, CIS, CdTe, and film silicon modules. Build a technology base upon which these advanced PV technologies can successfully improve manufacturing and continue to progress in terms of performance, reliability, and reduced cost for products meant to compete in the PV marketplace. Sustain innovation to support progress toward ambitious long-term PV cost and performance goals (e.g., 15% modules at under $50/m2 and capable of lasting 30 years) appropriate for cost-competitive PV electricity. Accomplishments Four JOULE milestones were met. Two Technology Partners broke ground on major manufacturing expansions (First Solar 50 MWp, and Uni-Solar 25 MWp). Production of thin films in the United States grew from 12 MWp in 2003 to an estimated >40 MWp in 2005. Future Directions � Continue to address key issues supporting the transition to successful first-time manufacturing or major production expansion in each thin film. � Significantly reduce CIS and CdTe layer thicknesses in cells and support transfer of this to manufacturing. � Direct CdTe research toward higher voltage. � Investigate nano-crystalline bottom cells for thin-film silicon multijunctions.___________________________________________
Venue	DOE NREL Annual Report
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Word document)
Resource Date	02/2006

Post Date	01/25/2006
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 16.5 MB)
Author	R. W. Birkmire
Description	CdTe, CIS, CIGS, a-Si, thin Si
Venue	Annual Report to National Renewable Energy Laboratory under Subcontract No. ADJ-1-30630-129/05/04 to 9/04/05
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	01/2006

Post Date	12/27/2005
Title	DEVELOPMENT OF A WIDE BANDGAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(MS Word 279 KB)
Author	W. N. Shafarman
Description	CuIn1?xGax(Se1?ySy)2 and Cd1?xZnxTe thin film alloys are being developed for use in wide bandgap cells to be incorporated into high performance tandem solar cells. For CuIn1?xGax(Se1?ySy)2, films the relative Cu-flux during deposition is critical to controlling the Se and S incorporation. A bi-layer process has been developed which results in a graded composition and gives improved device performance, primarily due to higher FF attributed to improved current collection. Cd1?xZnxTe-based cells are fabricated with absorber layers deposited by vapor transport deposition at 550�C with composition 0 ? x ? 0.6. Processes have been developed to fabricate devices which retain the composition of the deposited absorbers and have JSC limited primarily by the window layer optics.
Venue	2005 DOE Solar Review
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	12/2005

Post Date	11/11/2005
Title	POLYCRYSTALLINE THIN FILM DEVICE DEGRADATION STUDIES
Link	(PDF 85 KB) Download Acrobat Reader.
Author	D. Albin
Description	Oxygen during vapor CdCl2 (VCC) treatments significantly reduced resistive shunts observed in CdS/CdTe polycrystalline devices using thinner CdS layers during 100 �C, open-circuit, 1-sun accelerated stress testing. Cu oxidation resulting from the reduction of various trace oxides present in as-grown and VCC treated films is the proposed mechanism by which Cu diffusion, and subsequent shunts are controlled. Graphite paste layers between metallization and CdTe behave like diffusion barriers and similarly benefit device stability. Ni-based contacts form a protective Ni2Te3 intermetallic layer that reduces metal diffusion but degrades performance through increased series resistance.
Venue	DOE Solar Review Meeting 2005 paper
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	11/10/2005

Post Date	11/23/2005
Title	LOW TOXIC PROCESSING OF THIN AND ULTRA-THIN CIGSS ABSORBER SOLAR CELLS
Link	(MS Word 1.6 MB)
Author	N. G. Dhere
Description	CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells were prepared on molybdenum coated glass substrates. A low toxic approach using diethylselenide (DESe) as a selenium source was used for selenization of metallic precursors. Magnetron sputtering technique which is easy to scale up was used for deposition of back contact, metallic precursors and transparent and conducting oxide. A compact and large-grain absorber layer was produced by heating the elemental stack at 475-500oC in the diluted DESe gas. The threshold limit value (TLV) for DESe is 5 times less stringent than that of H2Se. After stabilizing deposition and selenization/sulfurization parameters on a 2.75 ?m thick absorber layer, preliminary experiments were carried out on an ultra-thin () absorber to reduce indium consumption. Rapid Thermal Processing (RTP) technique was developed as an alternative to conventional selenization and sulfurization to reduce the process time and thermal budget, thus enhancing throughput
Venue	2005 DOE Solar Review
Source	FLorida Solar Energy Center
Document Type	Annual Report (Word document)
Resource Date	11/2005

Post Date	11/17/2005
Title	UNDERSTANDING THE PHYSICS OF CDS-BASED PV: BAND DIAGRAM, INTERFACES, AND NONUNIFORMITIES
Link	(MS Word 120 KB)
Author	V. G. Karpov
Description	Our recent discovery of piezo-PV coupling together with other indicative evidence suggest an adequate band diagram for CdS based thin-film PV. The proposed model is solved analytically leading to numerous predictions that include lack of the carrier collection from CdS, buffer layer effects, and others. This understanding points at new pathways for device improvement.
Venue	DOE Solar Review 2005
Source	University of Toledo
Document Type	Annual Report (Word document)
Resource Date	11/2005

Post Date	11/18/2005
Title	SIMPLIFIED HYBRID PROCESS: APPLICATION TO NORMAL, SUB-MICRON, AND LIGHT-TRAPPING CIGS DEVICES
Link	(PDF 185 KB) Download Acrobat Reader.
Author	B. Sang
Description	This paper summarizes the progress made by Energy Photovoltaics, Inc. (?EPV?) in CIGS photovoltaic technology during the past year. Three main results are described: (1) development and optimization of EPV?s second-generation simplified hybrid process for CIGS deposition involving both sputtering and evaporation; (2) development of sub-micron CIGS devices and modules, and (3) production of a new back reflector layer (TiN) by hollow cathode sputtering. These achievements have increased CIGS throughput, reduced In consumption, and paved the way to ultra-thin, light trapping CIGS devices and modules.
Venue	DOE Solar Review 2005
Source	Energy Photovoltaics
Document Type	Annual Report (Adobe Postscript file)
Resource Date	11/2005

Post Date	02/14/2005
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 2.8 MB)
Author	N. G. Dhere
Description	Efforts of during the Year one consisted of scaling-up from small 1"x1" to 4"x4" substrate area. Activities in second year were mainly focused on stabilizing the parameters for large areas so as to obtain highly efficient CIGSS thin film solar cells. As a part of this, thickness optimization over large area (6"x4") for both DC and RF magnetron sputtering was taken up during initial period of second year. Routine depositions of CIGS2 absorber layer were carried out after stabilizing the thickness-uniformity, deposition parameters for molybdenum back contact, metallic precursors, and sulfurization heat treatment cycle. Experiments were carried out for improving cadmium sulfide heterojunction partner layer and recycling of the CdS waste, thus reducing the problem of toxic waste disposal. Selenization/Sulfurization furnace unit donated by Shell (formerly Siemens Solar) was refurbished and made operational. Two scrubbers were commissioned and connected to the furnace. CM4 analyzer for detecting H2S/H2Se gas leaks was coupled with scrubber and central alarm unit of the building. Electron beam assembly was received and tested. Malfunctioning of the unit continues and is being presently addressed.
Venue	NREL contract no. NDJ-2-30630-03, UCF/FSEC
Source	FLorida Solar Energy Center
Document Type	Annual Report (Word document)
Resource Date	10/20/2005

Post Date	04/05/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2- BASED SOLAR CELLS
Link	(PDF 584 KB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	CdTe CSS and CIGS sputtering
Venue	NDJ-2-30630-18 PHASE II
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	03/2005

Post Date	02/17/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS
Link	(MS Word 7.7 MB)
Authors	R. W. Birkmire, S. S. Hegedus, B. E. McCandless, W. N. Shafarman, et al.
Description
Venue	ADJ-1-30630-12 9/05/03 to 9/04/04
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	10/2004

Post Date	03/04/2005
Title	MANUFACTURING PROCESS ADVANCEMENTS FOR FLEXIBLE CIGS PV ON STAINLESS FOIL
Link	(PDF 111 KB) Download Acrobat Reader.
Authors	L. J. Simpson, et al.
Description
Venue	NCPV Review 2004
Source	Global Solar
Document Type	Annual Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	03/04/2005
Title	LAB TO LARGE SCALE TRANSITION FORNON-VACUUM THIN FILM CIGS SOLAR CELLS
Link	(MS Word 3.9 MB)
Author	V. K. Kapur
Description	The primary objective of this research is to streamline ISET's ink based non-vacuum process for fabricating efficient CIGS modules to lower the cost of module production << $1.0/watt. To achieve this objective, ISET has focused R&D efforts on investigating topics that directly impact the ultimate cost of processing CIGS modules. These topics of concern include (i) module output and therefore the solar cell and the module efficiency, (ii) overall process yield ? which requires developing a process that offers a very high degree of repeatability for every manufacturing step, and (iii) a process approach that maximizes the utilization of the materials used.
Venue	August 1, 2003 to July 31, 2004 NREL SUBCONTRACT NO. XCQ-230630-30
Source	ISET
Document Type	Annual Report (Word document)
Resource Date	08/2004

Post Date	03/03/2005
Title	REPORT ON ALTERNATIVE BUFFER LAYER TECHNOLOGIES - YEAR II
Link	(PDF 382 KB) Download Acrobat Reader.
Author	T. J. Anderson
Description
Venue	ADJ-2-30630-13
Source	University of Florida, Gainesville
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/19/2004

Post Date	03/04/2005
Title	TOLERANCE OFF THREE-STAGE CIGS DEPOSITION TO VARIATIONS IMPOSED BY ROLL&MDASH;TO&MDASH;ROLL PROCESING
Link	(PDF 976 KB) Download Acrobat Reader.
Authors	M. E. Beck, I. L. Repins
Description	Research under this program consists of four basic parts to examine the tolerance of the established laboratory process to variations in deposition procedures: 1. Setting up the National Renewable Energy Laboratory (NREL)-developed three-stage CIGS laboratory process in a bell jar. (Phase I) 2. Characterizing the GSE roll-to-roll production chambers and device finishing steps in terms of the variables important to the laboratory processes. (Phase II ) 3. Using the bell jar system to step incrementally from the NREL process to the conditions experienced by a sample during manufacturing, and characterizing the resulting films and devices. (Phase II and III) 4. Applying the process sensitivity information gained from the bell jar system to the production systems to realize improved device performance, yield, and process robustness. (Phase II and III)
Venue	Phase II Annual Report May 2003 ? May 2004 Thin Film Partnership Subcontract # ZDJ-2-30630-14
Sources	Global Solar; ITN Energy Systems
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/2004

Post Date	02/17/2005
Title	LIQUID-PHASE DEPOSITION OF ALPHA-CIS THIN LAYERS
Link	(PDF 2.3 MB) Download Acrobat Reader.
Authors	F. Ernst, P. Pirouz
Description	The goal of our project is to fabricate single-phase -CIS (alpha-Cu-In-Se, CuInSe 2) thin films for photovoltaic applications from a liquid phase (a Cu?In?Se melt). This approach of "liquid-phase deposition" (LPD) is based on the new phase diagram we have established for Cu?In?Se, the first complete equilibrium phase diagram of this system. The construction of the sliding-boat reactor was completed in the fourth quarter of Phase I. First tests have been performed, and we are confident that the new construction will enable us able to deposit thinner layers with better adhesion and to advance the quality of their microstructural characterization.
Venue	Subcontract XDJ-3-30630-33, Case Western, 1st Annual Report
Source	Case Western
Document Type	Annual Report (Adobe Postscript file)
Resource Date	02/11/2004

Post Date	03/03/2005
Title	THIN-FILM PHOTOVOLTAIC PARTNERSHIP ? PROCESS R&D FOR CIS-BASED THIN-FILM PV
Link	(MS Word 1.4 MB)
Author	D. E. Tarrant
Description
Venue	January 2003 ? January 2004 ZDJ-2-30630-16
Source	Shell Solar Industries
Document Type	Annual Report (Word document)
Resource Date	02/2004

Post Date	03/03/2005
Title	PLASMA&MDASH;ASSISTED COEVAPORATION OFF S AND SE FOR WIDE BAND GAP CHALCOPYRITE PHOTOVOLTAICS
Link	(PDF 850 KB) Download Acrobat Reader.
Author	I. L. Repins
Description	In terms of small-area device efficiency and module stability, CuInxGa1-xSe2 (CIGS) devices provide a benchmark for thin film photovoltaics. Nonetheless, there is significant opportunity for improvement in manufacture of CIGS devices. First, high-quality CIGS deposition requires high substrate temperatures (>500ºC), limiting the selection of substrate materials and increasing deposition cycle times due to heat-up and cool-down periods. Furthermore, current co-evaporation technology requires overpressure of chalcogens (Se2 or S2) during deposition, resulting in low material utilization and high equipment maintenance costs. Furthermore, the useful available energy bandgap expansion via alloying is limited to less than 1.3 eV.
Venue	Phase II Annual Report December 2002 ? December 2003 Thin Film Partnership Subcontract #NDJ-2-30630-11
Sources	Colorado School of Mines, Golden, CO; ITN Energy Systems
Document Type	Annual Report (Adobe Postscript file)
Resource Date	01/2004

Post Date	01/21/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 26 KB)
Author	J. R. Sites
Description	Work was performed at Colorado State University on basic measurements of CIGS and CdTe solar cells fabricated at a number of collaborating laboratories. The goal is to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made.
Venue	Summary Report for 2003, Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	10/2003

Post Date	02/02/2005
Title	2003 DOE PV PEER REVIEW
Link	(PDF 716 KB) Download Acrobat Reader.
Author	N/A
Description	Review of DOE PV activities in 2003
Venue	US DOE EERE
Source	US DOE
Document Type	Annual Report (Adobe Postscript file)
Resource Date	09/30/2003

Post Date	02/09/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 4.6 MB)
Authors	R. W. Birkmire, S. S. Hegedus, B. E. McCandless, W. N. Shafarman, et al.
Description
Venue	Annual report ADJ-1-30630-12
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/04/2003

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 2.9 MB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	03/04/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 4.5 MB)
Author	R. W. Birkmire
Description
Venue	ADJ-1-30630-12 9/05/02 to 9/04/03
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	03/03/2005
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN-FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 37 KB)
Author	R. W. Birkmire
Description
Venue	PV Program Contract Summary Report Thin-film PV Partnership Program
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	02/17/2005
Title	LAB TO LARGE SCALE TRANSITION FOR NON-VACUUM THIN FILM CIGS SOLAR CELLS
Link	(PDF 414 KB) Download Acrobat Reader.
Author	V. K. Kapur
Description	The purpose of this subcontract, as part of the R&D Partners category is to, (i) identify the challenges that ISET may face in the process of making a 'Lab to Large Scale' transition for its ink based non-vacuum process in production of thin film CIGS solar cells and modules, (ii) develop workable solutions for these challenges such that they can readily be implemented in a large-scale processing line for CIGS modules.
Venue	Phase I August 1, 2002 July 31, 2003 XCQ-230630-30
Source	ISET
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/2003

Post Date	03/04/2005
Title	ADVANCED CIGS PHOTOVOLTAIC TECHNOLOGY
Link	(MS Word 192 KB)
Author	A. E. Delahoy
Description	1) Optimization of large size CIGS deposition in Zeus, and module performance 2) Mini-module performance and process improvement in Hercules 3) Other device configurations 4) CdS process and surface treatment research 5) Interconnection 6) AR coating
Venue	RDJ-2-30630-21
Source	Energy Photovoltaics
Document Type	Annual Report (Word document)
Resource Date	06/17/2003

Post Date	02/17/2005
Title	UNDERSTANDING THE STRUCTURAL AND CHEMICAL BASIS OF CHALCOPYRITE SOLAR CELL OPERATION.
Link	(PDF 967 KB) Download Acrobat Reader.
Authors	I. M. Robertson, A. Rockett
Description	We studied three kinds of samples from IEC, University of Delaware. The growth procedure and resulting efficiencies of devices produced from each sample are different, and are different from the industrial films. All samples except the Shell Solar sample were received as completed devices with CdS junctions patterned, and transparent oxide coatings.
Venue	Subcontract ADJ-2-30630-26, University of Illinois
Source	University of Illinois
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/31/2003

Post Date	03/03/2005
Title	THIN-FILM PHOTOVOLTAIC PARTNERSHIP ? PROCESS R&D FOR CIS-BASED THIN-FILM PV
Link	(MS Word 3.9 MB)
Authors	R. Gay, D. E. Tarrant
Description
Venue	ZDJ-2-30630-16 April 24, 2002 ? January 31, 2003
Source	Shell Solar Industries
Document Type	Annual Report (Word document)
Resource Date	02/2003

Post Date	02/08/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN_1-XGA_XSE₂
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	This project addresses two thin film technologies CdTe and CIGS. The CdTe component of the project has three task areas. These are: development of simplified processing for the fabrication of CdTe solar cells correlation of the long term stability with process/device characteristics.
Venue	Phase I Final Report to NREL NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	2003

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 1.2 MB)
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CdTe and CI(G)S solar cells fabricated at a number of collaborating laboratories. The goal has been to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made. Special emphasis was given to the differences in CdTe cells, both as-deposited and after elevated-temperature stress, that result from variations in the amount of back-contact copper.
Venue	NREL Phase I September 2001 - August 2002 Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2002

Post Date	02/15/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 1.2 MB)
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CdTe and CI(G)S solar cells fabricated at a number of collaborating laboratories. The goal has been to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made. Special emphasis was given to the differences in CdTe cells, both as-deposited and after elevated-temperature stress, that result from variations in the amount of back-contact copper. The second area of study has been further development of small-spot measurement of micro-nonuniforities, including those that develop during temperature stress. The facility focuses a laser beam onto a solar cell with 1-mm beam size, 1-mm resolution and repeatability, and one-sun intensity. The third task has been the determination of defect-state densities in CIGS cells by low-temperature capacitance measurements. Emphasis has been given to the comparisons between CIGS absorbers fabricated by different techniques and among different strategies for the buffer between absorber and transparent contact. The final task area has been numerical simulations of CdTe and CI(G)S cells. Replication of experimental data has been successful in both cases. The CdTe CIGS studies have illuminated the effects of thickness variations in the CdS and CdTe layers, while more recent CIGS studies have shown the impact of the CdS/CIGS conduction band offset on light/dark superposition.
Venue	Subcontract ADJ-1-30630-06 Phase I September 2001 - August 2002
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2002

Post Date	03/03/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2- BASED SOLAR CELLS
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description
Venue	NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	2002

Post Date	04/27/2009
Title	PROCESSING MATERIALS DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 1.6 MB) Download Acrobat Reader.
Authors	R. W. Birkmire, W. N. Shafarman, E. Eser, S. S. Hegedus, B. E. McCandless, K. D. Dobson, S. Bowden
Description	This report describes results achieved under this subcontract to develop and understand thin-film solar cell technology associated to CuInSe2 and related alloys, a-Si and its alloys, and CdTe. This includes application of a-Si to c-Si wafer-type cells, as well. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability, and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for developing viable commercial processes and to improve module performance. The generic research issues addressed are: 1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; 2) device characterization relating the device performance to materials properties and process conditions; 3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; 4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and 5) evaluation of cell stability with respect to illumination, temperature, and ambient and with respect to device structure and module encapsulation.
Venue	Institute of Energy Conversion (IEC), University of Delaware, subcontract ADJ-1-30630-12, Final Report
Source	University of Delaware
Document Type	Final Report (Adobe Postscript file)
Resource Date	04/2009

Post Date	05/11/2009
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 2.5 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The project goals have been to (1) reliably and quantitatively separate individual performance loss mechanisms, (2) expand the tools available for such measurement and analysis, (3) refine the physical explanations for performance losses, and (4) suggest fabrication approaches or modifications that can reduce these losses. A number of studies relating to the fundamental operation of CIGS and CdTe solar cells were performed during the subcontract period. In addition, we have expanded our light-beam-induced-current (LBIC) capabilities and the formalism needed to evaluate spatial nonuniformities, and we have analyzed the effective efficiency to be expected from commercial thin-film modules
Venue	Colorado State University, subcontract XXL-5-44205-03, Final Report
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	01/2009

Post Date	10/20/2006
Title	FUNDAMENTAL MATERIALS RESEARCH AND ADVANCED PROCESS DEVELOPMENT FOR THIN-FILM CIS-BASED PHOTOVOLTAICS
Link	(PDF 7.9 MB) Download Acrobat Reader.
Authors	T. J. Anderson, S. S. Li, O. D. Crisalle, V. Craciun
Description	The objectives for this thin-film copper-indium-diselenide (CIS) solar cell project cover the following areas: Develop and characterize buffer layers for CIS-based solar cell; grow and characterize chemical-bath deposition of Znx Cd1-xS buffer layers grown on CIGS absorbers; study effects of buffer-layer processing on CIGS thin films characterized by the dual-beam optical modulation technique; grow epitaxial CuInSe2 at high temperature; study the defect structure of CGS by photoluminescence spectroscopy; investigate deep-level defects in Cu(In,Ga)Se2 solar cells by deep-level transient spectroscopy; conduct thermodynamic modeling of the isothermal 500�C section of the Cu-In-Se system using a defect model; form ?-CuInSe2 by rapid thermal processing of a stacked binary compound bilayer; investigate pulsed non-melt laser annealing on the film properties and performance of Cu(In,Ga)Se2 solar cells; and conduct device modeling and simulation of CIGS solar cells.
Venue	University of Florida, subcontract ADJ-2-30630-13, Final Report
Source	University of Florida, Gainesville
Document Type	Final Report (Adobe Postscript file)
Resource Date	09/2006

Post Date	07/31/2006
Title	THIN-FILM PHOTOVOLTAIC PARTNERSHIP PROGRAM CIS MODULE PROCESS R&D
Link	(MS Word 13.4 MB)
Authors	D. E. Tarrant, R. Gay
Description	Shell Solar Industries (SSI), formerly Siemens Solar Industries, has pursued the research and development of CuInSe2-based thin film PV technology since 1980. At the start of subcontract activities with NREL, SSI had demonstrated a 14.1% efficient 3.4 cm2 active-area cell, unencapsulated integrated modules with aperture efficiencies of 11.2% on 940 cm2 and 9.1% on 3900 cm2, and an encapsulated module with 8.7% efficiency on 3883 cm2. In-depth analysis of stability and outdoor reliability is also reported.
Venue	NREL Subcontract #ZXL-5-44205-04
Source	Shell Solar Industries
Document Type	Final Report (Word document)
Resource Date	06/2006

Post Date	05/30/2006
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2 CELLS
Link	(PDF 1.0 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	This is the final report for the 3-year project with subcontract # NDJ-2-30630-18. The CdTe section of the report is organized in 2 major sections: (a) a summary of the activities and major results obtained during the first two 2 years (covered in Annual Reports I & II), and (b) activities for year 3. Additional details will be provided within the subsequent sections.
Venue	NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Final Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	02/10/2006
Title	LIQUID-PHASE DEPOSITION OF CIS THIN LAYERS FINAL REPORT FEBRUARY 2003 ? JULY 2005
Link	(PDF 1.1 MB) Download Acrobat Reader.
Author	F. Ernst
Description	The goal of the project on which this report is based was to fabricate single-phase CIS (?-Cu?In?Se, stoichiometric composition: CuInSe2) thin films for photovoltaic applications from a liquid phase ? a Cu?In?Se melt of appropriate composition. This approach of ?liquid-phase deposition? (LPD) is based on the new phase diagram we have established for Cu?In?Se, the first complete equilibrium phase diagram of this system.1?3 Fig. 1 shows the liquidus projection of the phase diagram ? the surface indicating the temperature at which first solid material begins to form when cooling down from high temperatures at which the material is entirely liquid. The liquidus projection exhibits four composition fields in which the primary solid phase, i. e. the first solid material that forms on cooling down from an entirely liquid state, is ?-CuInSe2. Remarkably, none of the four composition fields is anywhere near the stoichiometric composition (CuInSe2) of ?-CuInSe2
Venue	*Subcontract Report*
Source	Case Western
Document Type	Final Report (Adobe Postscript file)
Resource Date	02/2006

Post Date	03/02/2006
Title	CIGSS THIN FILM SOLAR CELLS
Link	(PDF 545 KB) Download Acrobat Reader.
Author	N. G. Dhere
Description	This report describes the I-III-VI2 compounds that are developing into a promising material to meet the energy requirement of the world. CuInSe2 (CIS) and its alloy with Ga and S have shown long-term stability and highest conversion efficiency of 19.5%. Among the various ways of preparing CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells, co-evaporation and sputtering techniques are the most promising. Sputtering is an established process for very high-throughput manufacturing. ARCO Solar, now Shell Solar, pioneered the work in CIS using the sputtering technique. The two-stage process developed by ARCO Solar involved sputtering of a copper and indium layer on molybdenum-coated glass as the first step. In the second step, the copper-indium layers were exposed to a selenium-bearing gas such as hydrogen selenide (HSe) mixed with argon. The hydrogen selenide breaks down and leaves selenium, which reacts and mixes with the copper and indium in such a way to produce very high-quality CIS absorber layer. Sputtering technology has the added advantage of being easily scaled up and promotes roll-to-roll production on flexible substrates. Preliminary experiments were carried out. ZnO/ZnO:Al deposition
Venue	Florida Solar Energy Center, Subcontract NDJ-2-30630-03, Final Report, NREL/SR-520-39486
Source	FLorida Solar Energy Center
Document Type	Final Report (Adobe Postscript file)
Resource Date	02/2006

Post Date	10/05/2005
Title	PV MODULE TEST REPORT
Link	(PDF 21 KB) Download Acrobat Reader.
Author	Althaus
Description	13.52% STC efficiency, aperture area 727.62cm2, size 30x30cm, frameless, aperture area quoted w/o busbars
Venue	TUV module measurement report
Source	Shell Solar GMBh
Document Type	Final Report (Adobe Postscript file)
Resource Date	09/06/2005

Post Date	05/11/2005
Title	DEVICE PHYSICS OF THIN-FILMPOLYCRYSTALLINE CELLS AND MODULES SUMMARY REPORT FOR 2004, SUBCONTRACT ADJ-1-30630-06
Link	(MS Word 27 KB)
Author	J. R. Sites
Description	Task 1: Whole-cell analysis. The J-V distortions in CIGS cells due to an excessive spike in the conduction-band offset have been broadly documented and explained. The effects of a copper deficiency in the CdTe back contact have been similarly documented and explained. The process for systematic quantification of individual loss mechanisms in both types of cells has been refined and made more routine. Task 2: Highly focused light spot. Light-beam-induced-current (LBIC) measurements have shown that changes is CdTe cell response essentially always occur in localized regions. Additional refinements in cell-mounting, measurement, and display techniques have also made LBIC measurements more routine. Task 3: Defect-states. Low-temperature capacitance measurements with CIGS cells were used to compare absorbers fabricated by evaporation and by selenization, and to compare CdS and Cd-partial-electolyte buffer layers. CdTe photoluminescence was used to identify a key defect state as a copper/oxygen donor complex approximately 150 meV below the conduction band. Task 4. Numerical simulation. One project documented the limitation to cell voltage due to the CdS/CIGS conduction-band offset. A second showed that grading profiles in standard-thickness CIGS absorbers lead at best to only a modest increase in cell efficiency. A third project showed that a broad range of features seen in CdTe quantum-efficiency measurements can be explained with a simple three-layer model.
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Final Report (Word document)
Resource Date	05/2005

Post Date	05/11/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(PDF 3.0 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The first area of study has been whole-cell analysis. Individual projects have included development of more effective separation of losses, the role of copper incorporation and migration with CdTe cells, the current-voltage consequences of the conduction-band offset in CdS/CIGS cells, alternative buffers for CIGS cells, and the development of the CurVA software for analysis of current-voltage curves. The second area of study has been the use of a highly focused light spot (LBIC) to investigate spatial variations in polycrystalline solar cells. The local effects of elevated- temperature stress on CdTe cells has received the most attention, but we have also demonstrated that LBIC can be combined with other non-uniformity studies on the same cell and that it is possible to partially construct the J-V curve at individual local positions. The third task has been the study of defect-states. With CIGS cells, we used lowtemperature capacitance measurements to compare absorbers fabricated by evaporation with those made by selenization and to compare CdS buffer layers with the Cd-partialelectrolyte. For CdTe, photoluminescence from single crystals with controlled introduction of copper and oxygen has been compared with that from solar-cell material. The final task area has been numerical simulation. We have defined and advocated a set of baseline parameters for CIGS and CdTe cells. Specific projects have included explanations of apparent quantum- and collection-efficiency effects, the impact of conduction-band offset on current-voltage curves, the effects of absorber grading in CIGS cells, and the 2-D analysis of grain-boundary effects.
Venue	ADJ-1-30630-06 September 2001 - October 2004
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	05/2005

Post Date	04/19/2005
Title	PLASMA-ASSISTED COEVAPORATION OF S AND SE FOR WIDE BAND GAP CHALCOPYRITE PHOTOVOLTAICS
Link	(MS Word 17.7 MB)
Authors	I. L. Repins, C. Wolden
Description	ITN Energy Systems (ITN) and lower-tier subcontractor Colorado School of Mines (CSM) explore the replacement of the molecular chalcogen precursors during deposition (e.g. Se2 or H2Se) with more reactive chalcogen monomers or radicals (e.g. Se). Molecular species are converted to atomic species in a low-pressure inductively-coupled plasma (ICP). The thermodynamics that motivate this approach are illustrated in Figure 1. This diagram shows the changes in Gibbs free energy for CuInSe2 (left) and CuInS2 (right) synthesis from various chalcogen sources.[i],[ii] The formation energy of copper and indium are zero, so the reactant energy simply reflects the chalcogen source. Sulfur and selenium both sublime as dimers that may readily oligomerize into ring structures of Sn or Sen, where n varies from 2 [i] 78th Edition of the CRC Handbook of Chemistry and Physics, 78th Ed, Editor D. R. Lide, (CRC Press, Boca Raton) 1997. [ii] H. Migge and J. Grzanna, ?Thermochemistry in the system Cu-In-S at 723K,? J. Mater. Chem., 9 (1994.) pp. 125-128.
Venue	subcontract ndj-2-30630-11
Sources	Colorado School of Mines, Golden, CO; ITN Energy Systems
Document Type	Final Report (Word document)
Resource Date	04/15/2005

Post Date	04/18/2005
Title	ADVANCED PHOTOVOTAIC CIGS TECHNOLOGY
Link	(MS Word 1.5 MB)
Authors	A. E. Delahoy, L. Chen
Description	EPV has conducted research to help generate a technology base for production of CIGS PV modules using vacuum deposition of CIGS onto glass. This strategy is consistent with the observation that, despite there being several approaches to forming device quality CIGS, vacuum deposition has maintained the world record for the highest efficiency CIGS device. This record currently stands at 19.5% (692mV, 35.2 mA/cm2, FF 79.9%) for 0.41 cm2 device grown at NREL by the three-stage process [3]. To overcome barriers to manufacturing CIGS by vacuum deposition, EPV has developed vacuum equipment incorporating novel linear evaporation sources and magnetron sputtering cathodes designed for uniform coating of large (0.43m2) moving substrates
Venue	subcontract zdj-2-30630-21
Source	Energy Photovoltaics
Document Type	Final Report (Word document)
Resource Date	02/13/2005

Post Date	01/03/2006
Title	ENERGY PAY-BACK AND LIFE CYCLE CO2 EMISSIONS OF THE BOS IN AN OPTIMIZED 3.5 MW PV INSTALLATION
Link	tepbos2005
Author	J. Mason
Description	This study is a life-cycle analysis of the balance of system (BOS) components of the 3.5 MWp multi-crystalline PV installation at Tucson Electric Power's (TEP) Springerville, AZ field PV plant. TEP instituted an innovative PV installation program guided by design optimization and cost minimization. The advanced design of the PV structure incorporated the weight of the PV modules as support, thereby eliminating the need for concrete foundations. The estimate of the life-cycle energy requirements embodied in the BOS is 543 MJ/m2, a 71% reduction from those of an older central plant; the corresponding life-cycle greenhouse gas emissions are 29 kg CO2-eq. /m2. From field measurements, the energy payback time (EPT) of the BOS is 0.21 years for the actual location of this plant, and 0.37 years for average US insolation/temperature conditions. This is a great improvement from the EPT of 2 years estimated for an older central plant. The total cost of the balance of system components was $940 US per kWp of installed PV, another milestone in improvement. These results were verified with data from different databases and further tested with sensitivity- and data-uncertainty analyses. Key Words: PV plant; balance of system; life cycle assessment, energy payback, GHG emissions
Venue	website
Source	Tucson Electric
Document Type	Final Report (Hypertext link)
Resource Date	2005

Post Date	04/21/2005
Title	PVACCEPT
Link	PVACCEPT
Author	N/A
Description	PVACCEPT is a German-Italian research project, which was funded by the European Commission within the programme "Innovation and Small and Medium Sized Enterprises". The project aimed at designing and developing marketable solar modules for electricity generation, which are designed in a way to enable their sensitive and inconspicuous integration into old buildings, historical sites, and protected landscapes. The project has officially started on 1st July 2001, and is concluded since 31st December 2004.
Venue
Sources	University of Arts, Berlin; University of Siena
Document Type	Final Report (Hypertext link)
Resource Date	12/2004

Post Date	03/04/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(PDF 3.0 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The first area of study has been whole-cell analysis. Individual projects have included development of more effective separation of losses, the role of copper incorporation and migration with CdTe cells, the current-voltage consequences of the conduction-band offset in CdS/CIGS cells, alternative buffers for CIGS cells, and the development of the CurVA software for analysis of current-voltage curves. The second area of study has been the use of a highly focused light spot (LBIC) to investigate spatial variations in polycrystalline solar cells. The local effects of elevated- temperature stress on CdTe cells has received the most attention, but we have also demonstrated that LBIC can be combined with other non-uniformity studies on the same cell and that it is possible to partially construct the J-V curve at individual local positions. The third task has been the study of defect-states. With CIGS cells, we used lowtemperature capacitance measurements to compare absorbers fabricated by evaporation with those made by selenization and to compare CdS buffer layers with the Cd-partialelectrolyte. For CdTe, photoluminescence from single crystals with controlled introduction of copper and oxygen has been compared with that from solar-cell material. The final task area has been numerical simulation. We have defined and advocated a set of baseline parameters for CIGS and CdTe cells. Specific projects have included explanations of apparent quantum- and collection-efficiency effects, the impact of conduction-band offset on current-voltage curves, the effects of absorber grading in CIGS cells, and the 2-D analysis of grain-boundary effects.
Venue	September 2001 - October 2004 ADJ-1-30630-06
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	11/2004

Post Date	02/04/2005
Title	STUDY OF POTENTIAL COST REDUCTIONS RESULTING FROM SUPER-LARGE-SCALE MANUFACTURING OF PV MODULES
Link	(PDF 768 KB) Download Acrobat Reader.
Authors	R. Arya, M. Keshner, K. Zweibel
Description	Technology investments by the U.S. government Dept. of Energy, National Renewable Energy Lab (NREL) and others over the past 30 years have positioned the Solar Energy industry to undergo an inflection. The technology is now very close to good enough. The key issue is cost.
Venue	NREL final report NREL/SR-520-36846 Subcontract No. ADJ-3-33631-01
Sources	Hewlett Packard; National Renewable Energy Laboratory
Document Type	Final Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(PDF 3.0 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CIGS and CdTe solar cells fabricated at a number of collaborating laboratories. The goal has been to explain several features seen in these measurements and quantitatively assess their impact on device performance.
Venue	Subcontract ADJ-1-30630-06 Final Report to NREL
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Final Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	03/11/2005
Title	LEARNING FROM THE SUN
Link	(PDF 3.3 MB) Download Acrobat Reader.
Authors	E. A. Alsema, G. J. Schaeffer, et al.
Description	Analysis of the use of experience curves for energy policy purposes: The case of photovoltaic power. Final report of the Photex project
Venue	ECN-C--04-035
Source	Photex
Document Type	Final Report (Adobe Postscript file)
Resource Date	08/2004

Post Date	02/11/2005
Title	WORKSHOP ON LIFE CYCLE ANALYSIS AND RECYCLING OF SOLAR MODULES - THE "WASTE" CHALLENGE
Link	(PDF 12.5 MB) Download Acrobat Reader.
Author	A. Jager-Waldau
Description	First, to rise the awareness of the Photovoltaic Community about the European Directives 2002/96/EC on waste electrical and electronic equipment (WEEE) and 2002/95/EC on the restriction of the use of certain hazardous substances in electrical and electronic equipment (ROHS), which have to be implemented by the Member States in 2004. These directives will have a significant impact on the PV industry, not only because the future waste classification of PV modules is an important issue, but also the sustainability and the green image of the PV industry as a whole has to be considered. The second focus was on Life Cycle Assessment the correct evaluation of External Costs and the Recycling of Solar Modules, which will help to avoid these problems. The workshop gave an overview about the current scientific and political discussion, identified problems and showed the way for possible solutions.
Venue	European Commission EUR 21101 EN
Source	European Commission Joint Research Centre
Document Type	Final Report (Adobe Postscript file)
Resource Date	03/19/2004

Post Date	02/07/2005
Title	PV STATUS REPORT 2003
Link	(PDF 671 KB) Download Acrobat Reader.
Author	A. Jager-Waldau
Description	Research, Solar Cell Production and Market Implementation in Japan, USA and the European Union.
Venue	European Commission JRC EUR 20850EN
Source	Institute for Environment and Sustainability
Document Type	Final Report (Adobe Postscript file)
Resource Date	09/2003

Post Date	02/07/2005
Title	NUMERICAL MODELING AS A TOOL FOR ANALYZING THIN-FILM SOLAR CELLS AND INTERPRETING DEVICE AND MATERIAL CHARACTERIZATION MEASUREMENTS
Link	(PDF 116 KB) Download Acrobat Reader.
Author	J. L. Gray
Description	Detailed numerical modeling has proved to be a useful tool in developing many of the current PV technologies such as single crystal Si, GaAs, ? -Si, CdTe, and CIS, to name a few. The purpose of this work is to continue development of ADEPT (A Device Emulation Program and Tool) ? primarily to integrate it with MatLab™.
Venue	NREL Report, contract XAK-8-17619-36
Source	Purdue
Document Type	Final Report (Adobe Postscript file)
Resource Date	2003

Post Date	02/11/2005
Title	ENVIRONMENTAL ASPECTS OF PV POWER SYSTEMS
Link	(PDF 278 KB) Download Acrobat Reader.
Authors	E. A. Alsema, E. Nieuwlaar
Description	An expert workshop was held as part of the International Energy Agency Photovoltaic Power Systems Implementing Agreement Programme, to address these environmental aspects of PV power systems. The objectives of the workshop were: Review/overview of issues and approaches regarding environmental aspects of PV power systems; Enhanced clarity and consensus regarding well-known aspects like Energy Pay-Back Time; Identification of issues of environmental importance regarding PV power systems ('hot spots'); Identification of issues requiring further attention ('white spots');
Venue	IEA PVPS Task 1 Workshop 25-27 June 1997 Utrecht, The Netherlands Report no. 97072
Source	Utrecht University
Document Type	Final Report (Adobe Postscript file)
Resource Date	12/1997

Post Date	02/11/2005
Title	ENVIRONMENTAL ASPECTS OF SOLAR CELL MODULES
Link	(PDF 466 KB) Download Acrobat Reader.
Author	E. A. Alsema
Description	multicrystalline silicon, amorphous silicon, cadmium telluride and copper indium selenide are reviewed with special attention to future expected technology developments. For each module type an assessment is made of the potential environmental impacts in case of large scale implementation of the technology. In principle the entire module life cycle is taken into consideration: from resource mining, via module production and module utilization until module decommissioning and waste handling. In the report for each module type the following aspects are discussed: energy requirements and energy pay-back time, material requirements and resource depletion, environmental emissions, waste handling, possibilities for recycling of modules, occupational health and safety and external safety.
Venue	Report nr. 96074 ISBN 90-73958-17-2 Netherlands Agency for Energy and the Environment (NOVEM)
Source	Utrecht University
Document Type	Final Report (Adobe Postscript file)
Resource Date	08/1996

Quarterly Reports

Post Date	09/09/2008
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(PDF 94 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	Discusses (contac) barrier measurement technique, CdTe internal photoemission measurement, non-uniform CdTe barriers affecting "roll-over", CdTe cells with thin CdS layers, sheet resistance and fill factor issues, the effect of shunts on cell performance contour plots (correlations of Voc, Jsc, and FF with material parameters, and collaborative work.
Venue	Colorado State University, Fort Collins, CO, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/02/2009

Post Date	02/24/2009
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 110 KB) Download Acrobat Reader.
Author	C. Heske
Description	We have initiated a detailed study of the CdS/CIGSe interface formation for world-record-class samples. A substantial data set has been recorded, and additional data-taking is currently ongoing. A series of XPS survey spectra is shown that were taken as a function of CdS thickness. Corresponding completed solar cell devices yielded efficiencies in the 15% range, while we are currently also investigating a sample series with efficiencies around 18%. These spectra, to-gether with detail spectra of each core level, the valence band maxima, and the work function are cur-rently being analyzed to develop a comprehensive picture of the electronic structure of these two CdS/CIGSe interface systems.
Venue	Subcontract XXL-5-44205-12 with U. Nevada, Las Vegas, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/15/2009

Post Date	03/13/2009
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	We have been applying junction capacitance methods to investigate the effects of Ga grading on a set of four CuIn1-xGaxSe2 (CIGS) sample devices at the National Renewable Energy Laboratory (NREL). One device was deposited with a uniform Ga depth profile (x=0.30), two were deposited so that the Ga fraction varied monotonically from near x=0.9 at the Mo back contact to either x=0.15 or x=0.25 at the junction interface, and the last device utilized a compositional variation close to NREL's optimal ?v-shaped? bandgap grading scheme. Following deposition, SIMS measurements were carried out at NREL to provide a detailed spatial map of the Ga/(Ga+In) ratios in the CIGS absorbers. One of the most revealing effects of Ga grading were obtained from our transient photocapacitance (TPC) and photocurrent (TPI) spectra. These measurements provided a spectral map of the optically induced release of carriers for photon energies from 0.6eV to 2eV. Comparing the two types of spectra enables one to distinguish majority from minority carrier processes. We also attempted to obtain additional spatial information by varying the applied DC bias to weight the spectral response to different regions relative to the barrier junction. The edge of the depletion region under different (steady-state) DC biases were estimated by the high frequency junction capacitance values. We concluded that we are really sampling regions farther from the junction.
Venue	University of Oregon, subcontract ZXL-5-44205-11, quarterly report
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/2008

Post Date	11/21/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure is painted. In February this year, the NREL group announced to have achieved a new world record effi-ciency (19.9%) for Cu(In,Ga)Se2 ?CIGSe? ? based thin-film solar cells (Ingrid Repins, Miguel A. Con-treras, Brian Egaas, Clay DeHart, John Scharf, Craig L. Perkins, Bobby To and Rommel Noufi, 19.9%-efficient ZnO/CdS/CuInGaSe2 Solar Cell with 81.2% Fill Factor, Prog. Photovolt. 16, 235 (2008).) This recent efficiency gain (compared to the former world record - 19.5%), is believed to be caused by a small ? but apparently significant ? change in the three-stage process. In comparison to the deposition process used earlier, the difference resulting in the recent world record CIGSe absorber was a termina-tion of the third (and thus last) stage without Ga and hence is considered to be ?In-terminated?. In order to shed light on the expected different chemical surface structure, we investigated a sample from the world record absorber batch (M2992) by x-ray photoelectron spectroscopy (XPS) and xray excited Auger electron spectroscopy (XAES). Both techniques are very surface sensitive (information depth a few nm) and thus well suited to address questions of surface termination. In addition, we also characterized a CIGSe absorber (M2995) deliberately terminated with Ga for comparison.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/15/2008

Post Date	11/04/2008
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
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Author	R. W. Birkmire
Description	We investigated processes to increase VOC in Cu(InGa)(SeS)2 solar cells using absorber layers formed by the reaction of precursors in H2Se / H2S which is typically low due to accumulation of Ga at the back of the reacted film. A two-step reaction of Cu-Ga-In precursors with partial reaction in H2Se at 400� ? 450�C followed by completion in H2S at 550�C has been used to form Cu(InGa)(SeS)2 films with uniform incorporation of the Ga. Scribing tests for monolithic integration by mechanical and laser scribing have been started. Initial attempts in mechanically scribing the molybdenum (Mo) layer (P1 scribe) with a programmable x-y mechanical scribing system resulted in tearing of the Upilex. Double stick tape was then used to secure the Upilex giving much improved results. However, the resulting scribe showed only partial removal of the Mo layer.
Venue	Institute of Energy Conversion, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/08/2008

Post Date	11/07/2008
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	Diifusion pump maintenance issues are reported. Molybdenum has emerged as the dominant choice for the back contact layer to CIS and CIGSeS chalcopyrite thin film solar cells. It is essential to deposit stress-free and relatively inert Mo films in order to achieve well adherent and highly efficient CIGSeS absorber thin film solar cells. Molybdenum layer in compressive stress mode layer at top has lower sheet resistance as compared to molybdenum layer in tensile stress mode. This low sheet resistance is desirable for metallized back contact layer for solar cells.
Venue	Florida Solar Energy Center, University of Central Florida, subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/29/2008

Post Date	07/12/2008
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	It is well known that fabricating Cu(InxGa1-x)Se2 (CIGS) thin-film photovoltaic devices on glass substrates containing sodium can boost the efficiency of the device by up to 50 %. Nonetheless, there is a surprising lack of consensus on how Na affects the CIGS network at the atomic level. For example, some published results claim that Na only acts during the growth of the CIGS, while others have found similar benefits to adding Na in a post-deposition treatment. Similarly, there is disagreement as to whether the Na acts in the bulk of the absorber or only at the grain boundaries. Researchers have also tried to understand the role of Na by investigating its effect on both the Se incorporation and the Ga content in the samples. All samples used in this study were fabricated at the Institute of Energy Conversion at the University of Delaware. Two pairs of co-deposited samples were examined. In each case one sample utilized the usual soda-lime glass substrate while the companion sample was deposited simultaneously on a substrate which substantially eliminated sodium from the resultant CIGS film.
Venue	University of Oregon, subcontract ZXL-44205-11, quarterly report
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/10/2008

Post Date	08/07/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Authors	C. Heske, M. Baer
Description	We have used x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XAES) to investigate the chemical surface structure of selected samples (both, front and back sides) directly taken out of GSE?s production process after each preparation step. Upon CIGSe formation preliminary data evaluation shows that the back side exhibits MoSe2 and absorber related XPS and XAES features. Compared to the front side, we find an increased amount of Ga on the back side which suggests a pronounced interaction with the front side upon roll-up.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/16/2008

Post Date	07/09/2008
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS"
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Author	J. R. Sites
Description	We continued our work on the relationship between voltage and CdS thickness with CdTe cells; the relationship between fill-factor of a cell or module and sheet resistance, geometry, current, and the JSC/VOC ratio; and the effects of local shunts on cell performance. Since the funding of the AVA incubator project took effect, I have shifted our work on CSU and AVA CdTe cells, and the reporting of those results, to the incubator project.
Venue	Coloradio State University, Subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/21/2008

Post Date	07/09/2008
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	Experiments were initiated for the comparison of CIGSeS absorber layers prepared under identical conditions on commercial Mo coated substrates and in-house prepared Mo coated back contact layers with or without SixNy diffusion barrier layers. CIGSeS absorber layers prepared on sodalime glass substrates with in-house prepared molybdenum back contact peeled off during selenization/sulfurization by RTP. All the films were deposited with starting layer of molybdenum in compressive stress mode that is known to be less adherent to glass substrate as compared to film grown in tensile mode. This could be the reason for peeling off the absorber films. Therefore, experiments are being continued with starting layer of molybdenum in tensile stress mode. CIGS2 solar cells were optimized for lower thickness values of absorber. Photovoltaic conversion efficiency of 10.12% was obtained for an absorber of thickness 1.5 ?m and an efficiency of 9.62% was obtained for an absorber of thickness 1.2 ?m.
Venue	Florida Solar Energy Center (U. Central Florida), subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/14/2008

Post Date	05/01/2008
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN-FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURING ISSUES
Link	(PDF 640 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	A substrate carrier was installed in the roll-to-roll system. The purpose of the carrier was to allow in-line deposition on both glass (rigid) and polyimide (flexible) substrates. Furthermore, using 4? to 6? of polyimide coupon per run is more cost effective than using 5? to 6? of material in each experiment. The carrier was tested with soda lime (SL) glass substrate at a temperature of 550�C and with polyimide substrate at a temperature of 450�C. The other effort pursued was the development of a Na source for incorporation into the in-line system. To that effect, an evaporation source identical to those used in the in-line system was installed in bell-jar type vacuum system. The evaporative characteristics of NaF from the source is presently being evaluated. When the quantitative picture is developed the information will be transferred to the NaF source that is being installed into the in-line system.
Venue	Institute of energy Conversion, U. delaware, subcontract ADJ-1-30630-12, monthly report (CIGS
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/20/2008

Post Date	04/11/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 247 KB) Download Acrobat Reader.
Author	C. Heske
Description	We have investigated different chalcopyrite absorbers from NREL (group of R. Noufi) and IEC (group of W. Shafarman). An intrinsic feature of Cu chalcopyrites is that their surface composition significantly deviates from the stoichiometric Cu : (In+Ga) : (S+Se) = 1 : 1 : 2 composi-tion in the absorber bulk. Surface-sensitive characterization techniques almost always indicate a Cu-poor surface composition. In consequence, the formation of an ordered defect compound at the absorber surface was suggested. Defect chalcopyrites with a composition ranging from 1 : 2 : 3.5 to 1 : 11 : 17 were proposed and corre-sponding (bulk) samples were synthesized. The optical characterization of these bulk materials show that the defect (Cu-poor) chalcopyrites have larger band gap energies (Eg) compared to their stoichiometric counterparts. For solar cell absorbers, direct determination of the surface band gap by UV photoelectron spectroscopy (UPS) and inverse photoemission (IPES) recently showed that Eg is indeed widened at the Cu-poor surface of absorbers with stoichiometric bulk composition. To investigate whether the composition of the chalcopyrite absorber has an impact on the formation of the Cu-poor, Eg-widened region and its extension into the absorber bulk, different chalcopyrite thin film solar cell absorbers have been investigated. We have used various photon and electron spectro-scopies with different information depths in order to gain depth-dependent Eg information. For all in-vestigated samples we find an increasing band gap energy with decreasing information depth and the formation of a surface region with significantly higher Eg. In addition, we find that the Eg-widened surface region extends further into the bulk of the absorber for the sulfur-free CIGSe absorber (i.e., the absorber with smaller bulk band gap) than for the CIGSSe absorber.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/15/2008

Post Date	12/13/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
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Author	L. Olsen
Description	Data were acquired for SSI mini-modules that were coated with PNNL barrier coatings based on the new polymer blend. Results were obtained for coated modules subjected to 85�C and dry conditions, and modules with barrier coatings of thicknesses ranging from 3 microns to 10 microns. The 85�C/Dry testing was done to determine if the coatings react in a negative way with the devices. We found that all coated modules were stable in the 85�C/Dry conditions. Figure 3 gives results for a module with a coating 10 microns thick. Basically, the module is stable. Thus, it is very clear that the SSI mini-module can tolerate 85�C and dry conditions, but not a stress of 86�C/85%RH. Figure 4 gives results for coated mini-modules with the results for a bare module shown for contrast. Although the PNNL barrier coatings have made a tremendous difference, degradation still occurs. The fact that all modules degrade at the same rate, regardless of coating thickness, provides an important clue as to the cause of the degradation. Based on our overall experience, the effectiveness of the barrier coatings should improve with thickness. In general, we find that there are three cell features that can lead to defects in the multi-layer coatings which in turn provide a path for water diffusion: (i) Surface roughness; (ii ) Inadequate edge seal; (iii) Cuts separating individual cells. Since the rate of degradation of efficiency is independent of the coating thickness, we suspect that features (ii) and (iii) are most likely responsible for causing pathways of moisture diffusion. Further studies are required before this problem(s) can be clearly identified. However, the results achieved with the new polymer blends in an 85/85 environment are very encouraging.
Venue	Pacific Northwest National Laboratory, subcontract DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/01/2007

Post Date	11/30/2007
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	CONTENTS 1. SixNy/Mo Deposition 2. CIGS2 THIN FILM SOLAR CELLS 3. ZnCdS AND ZnS AS ALTERNATIVE BUFFER LAYER FOR CIGS2 SOLAR CELLS 4. REFERENCES
Venue	Florida Solar Energy Center, University of Central Florida, subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/27/2007

Post Date	02/07/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Author	C. Heske
Description	We have derived the electronic structure of the CdS/CIGSe interface in thin film solar cells prepared by NREL. The conduction band alignment at the CdS/CIGSe interface is flat, as expected for a high efficiency CIGSe solar cell. Furthermore, we find direct evidence for a strong interface dipole. Together with the previously reported lack of significant intermixing at the CdS/CIGSe interface, we thus find a modified electronic and chemical interface structure compared to previously studied (less efficient) devices from other manufacturers.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44202-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/15/2007

Post Date	01/14/2008
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
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Authors	R. W. Birkmire, K. Mukati
Description	The PhD thesis dealing with control and modeling of the CIGS sources that was supported by this program has been completed. The tile of the thesis by Dr. K. Mukati is: AN ALTERNATIVE STRUCTURE FOR NEXT GENERATION REGULATORY CONTROLLERS AND SCALE-UP OF CU(INGA)SE2 THIN FILM CO-EVAPORATIVE PHYSICAL VAPOR DEPOSITION PROCESS (The Monthly report summarizes the abstract and key results)
Venue	Institute of Energy Conversion, University of Delaware, Subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/23/2007

Post Date	12/28/2007
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	Highly efficient CIGSeS thin film solar cells are prepared in a two stage process. Firstly, a molybdenum back-contact layers is deposited on sodalime glass substrates by DC magnetron sputtering. Earlier, a thin silicon oxide layer was employed underneath the molybdenum layer to minimize the uneven out-diffusion of sodium from sodalime glass substrate. Currently silicon nitride diffusion barrier is being deposited by reactive magnetron sputtering to act as a more efficient diffusion barrier for sodium. Since the presence of a small amount of Na during growth of the CIGSe absorber layer is beneficial, an optimum amount of Na is deposited on the Mo back contact layer. This is followed by the deposition of the metallic precursors on Mo-coated glass. Next the metallic precursors are selenized and sulfurized in diethyl selenide (DESe) and H2S ambient respectively. After achieving the highest efficiency of 13.73%, experiments were carried out to improve the material quality to further increase the efficiency. However, the price of DESe have sky rocketed (10 - 12 times) beginning the first quarter of 2007, since many of the companies that supplied the chemical have completely stopped the production. Therefore, an alternative selenium source, dimethyl selenide (DMSe) is being used. It has already given encouraging results. Moreover, a small set-up is being designed and built in collaboration with the UCF Department of Chemistry for the synthesis of DESe using a published process.
Venue	FSEC (U. Central Florida) subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/12/2007

Post Date	11/21/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 842 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	Experiments have been initiated in the in- line system to determine the effect of web transport speed on the Cu(InGa)Se2 film quality both in terms of the materials characteristics and device performance. The web used as a substrate was 50 microm thick UpilexS polyimide coated with 0.2 microm Mo(O). The baseline web speed has been 0.75"/min, corresponding to an apparent deposition time of 15.2 min for the deposition zone of 11.4". As a first experiment, a deposition was started at a web speed of 0.75"/min and after 4 ft of deposition the web speed was raised to 1"/min for another 5 ft of deposition. Samples taken at 2' and 7' from the leading edge, corresponding to web speeds of 0.75 and 1"/min were investigated. Table I gives the compositions of the Cu(InGa)Se2 films so sampled. Materials and device parameters are reported.
Venue	IEC, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/03/2007

Post Date	11/29/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
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Author	J. R. Sites
Description	During the past quarter, two students completed their PhD and one other is preparing for his defense. At the same time, we expanded our work on the analysis of cells with non-uniformities, we began a collaboration on CIGS made with laser-assisted deposition, and we continued several measurement and analysis projects in collaboration with other laboratories.
Venue	Colorado State University, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/24/2007

Post Date	08/15/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
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Author	L. Olsen
Description	The key objectives of the program are to develop low cost barrier coatings for CIS and CdTe solar cells and to develop an improved understanding of the effects of water on the stability of these types of cells. The scope of this work entails investigations multilayer, barrier coatings for CIS and CdTe thin film solar cells, and studies of stability issues, particularly those related to moisture ingress. Investigation of barrier coatings on SSI and CSU devices will continue in an effort to establish effective approaches encapsulate CIS and CdTe modules. Studies will also be directed towards issues concerning cost of the coating process. The program will be structured into three major tasks: (1) Barrier coatings and stability studies for CIS Solar Cells; (2) Barrier coatings and stability studies for CdTe solar cells; (3) Low cost coating process development.
Venue	PNNL, agreement DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/2007

Post Date	08/03/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
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Author	J. R. Sites
Description	Reports CIGS nonuniformities, CdTe efficiency (n-p vs. p-i-n), light bias QE, and CdS thickness variation in CdTe cells (all presented at the MRS Spring meeting)
Venue	Colorado State University (Sites), subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/27/2007

Post Date	08/15/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
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Author	L. Olsen
Description	Our investigations to date were based on Shell Solar, Inc. (SSI) cells and mini-modules. We found that these cells were extremely vulnerable to damp heat effects. These devices are no longer available to PNNL due to the closing of the Chatsworth CIGS operation. However, we have a supply of 2 in. x 2 in. mini-modules that were used in recent studies that are discussed in this report. Moisture ingress is apparently not an issue if modules are fabricated with glass-to-glass construction. It is clear, however, that CIGS cells and modules fabricated on flexible substrates must have an effective barrier coating. As a result, we plan to concentrate on establishing baseline information concerning the effects of damp heat on CIGS.
Venue	PNNL, agreement DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/2007

Post Date	05/30/2007
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES&NBSP;&NBSP;
Link	(PDF 212 KB) Download Acrobat Reader.
Author	C. Heske
Description	We could complete our picture of the deeply buried chalcopyrite/back contact interface by continuing our experiments at the Cu(In,Ga)Se2 ("CIGSe") and Cu(In,Ga)(S,Se2) ("CIGSSe")/back contact samples prepared by the group of W. Shafarman (Institute of Energy Conversion, University of Delaware). We find a pronounced chemical interaction between absorber and back contact, namely the formation of MoSe2 (or Mo(S,Se)2) and a diffusion of Ga into the Mo layer.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/2007

Post Date	06/15/2007
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	Research activities presented here focuses on developing CIGSeS thin films by depositing elemental precursor Cu-In-Ga by sputtering technique followed by selenization/sulfurization in either conventional furnace or by rapid thermal processing. During the first year, experiments were carried out to optimize conditions for both conventional and rapid thermal processing approaches. Also experiments were conducted on very thin absorber layers with both the conventional and rapid thermal processing approaches. These initial experiments towards optimizing the selenization parameters were discussed in detail in earlier reports. An efficiency of 11.99% has already been achieved for CuIn1-xGaxS2 (CIGS2)_ thin-film solar cells using Cu-rich precursors.
Venue	FSEC (U. Central Florida) subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2007

Post Date	05/30/2007
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	The addition of Na to the CIGS absorber layer is a commonly followed procedure, boosting the efficiency by up to 50% primarily through a sizeable increase in the open-circuit voltage (Voc) and the fill factor (FF). Although the positive role of Na is well known, there is an ongoing debate as to the exact mechanism of the beneficial effect of Na, with much of the debate centering around where in the cell the Na has its effect. Possible sites are grain boundaries, in the bulk of the grains, or the CdS/CIGS heterojunction. Recent experimental results appear quite contradictory, with one group finding no evidence of Na at the grain boundaries and another group concluding that the Na is only found in significant amounts at the grain boundaries. Another group hypothesizes that the Na acts only during the growth of the sample to organize and passivate point defects; however, this is disputed by similar benefits obtained through diffusion of Na into the sample in a post-deposition treatment. A pair of matched baseline (34017.12) and reduced Na (34017.32) samples were provided by the Institute of Energy Conversion. The samples were co-deposited at 550�C in a single deposition with a thickness of 2.0 ?m. The baseline film was deposited on a Mo-coated soda lime glass substrate and the reduced Na film was deposited on a substrate provided by Shell Solar which has a SiO2 diffusion barrier below the Mo. Both devices were completed with standard CdS, ZnO and ITO depositions and a Ni/Al grid. Drive-level capacitance profiles are displayed for the CIGS samples with and without Na. These profiles show similar overall shapes but more spatial variation in the sample with Na. The sample with Na shows a defect activating between 130 K and 190 K that is absent in the reduced Na sample. Without any prior knowledge of cell performance, one would predict that the more spatially uniform, reduced Na sample to be more efficient. Exactly the opposite is the case.
Venue	University of Oregon, ZXL-5-44205-11, quarterly report (Quarter 2)
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2007

Post Date	07/12/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMANTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 214 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	Characterization of the effect of the heat treatment (HT) at 250�C in flowing H2(4%)/Ar for 1 hour has been completed. SEM micrographs and compositional measurements on the nodules and on the smooth background are summarized. The as-sputtered film contains In nodules on a smooth Cu-Ga background. After the HT, the morphology does not change, but the composition has inverted, and the nodules are Cu-Ga rich.
Venue	IEC, Uiversity of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/21/2007

Post Date	03/16/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
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Author	R. W. Birkmire
Description	In this work, we characterize device performance as a function of variations in the two-step reaction. A baseline with 15 m / 450�C for the H2Se and 15 m / 550�C for the H2S reactions yielded similar composition to that previously reported with [Ga]/[In+Ga] = 0.2 and [S]/[Se+S] = 0.4 as measured by EDS. Device performance was also similar with VOC = 0.65V and h = 12.6% so the benefits of the Ga incorporation were realized in VOC. Process variations investigated include: 1. An increase in H2S reaction time to 20 m resulted in similar [Ga]/[In+Ga] but lower FF and JSC in the devices. This could be due to an interface collection barrier caused by too much S diffused into the Cu(InGa)(SeS)2 surface. Symmetric XRD and EDS are not very sensitive to a surface S layer and GIXRD measurements to characterize the near surface of the Cu(InGa)(SeS)2 have not been completed. 2. An increase in H2Se time to 30 minutes gave much lower [Ga]/[In+Ga], as reported previously, attributed to more complete reaction and consumption of the Cu9Ga4 phase during selenization. In addition, this leads to films with poor adhesion at the Mo/Cu(InGa)(SeS)2 interface and most attempts to make devices resulted in delamination after film reaction or during CdS bath deposition. On one sample, devices were completed and had lower VOC consistent with the low Ga composition. 3. Reducing the H2Se reaction time to 10 m gave a small increase in VOC but even lower JSC. 4. Reaction in H2Se at lower T = 400�C was investigated to determine if it might give better uniformity. With reaction time increased to 45 m, comparable results for composition and device performance were obtained but visual non-uniformities remained. In conclusion, the two-step reaction reproducibly enables the Ga to be uniformly incorporated and VOC > 0.62V to be attained. However, higher cell performance may require more precise optimization of the reaction conditions to optimize the S gradient and the current collection.
Venue	IEC, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/30/2007

Post Date	02/15/2007
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Authors	M. Baer, C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In the last months, we started to investigate CdS/CIGSe samples provided by the National Renewable Energy Laboratory. We do not find any evidence for a very strong intermixing process (i.e., S atoms diffusing into the substrate). However, the environment of the sulfur atoms at the growth start of the interface clearly deviates from a perfect CdS environment. Whether this is due to a less perfect crystalline structure (i.e., the formation of very small nm-scale nanoparticles) or some S diffusing into the CIGSe absorber can not unambiguously be differentiated.
Venue	U. Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/11/2007

Post Date	01/15/2007
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	Experiments were carried out to optimize the metallic precursor deposition for standard absorber preparation and selenization/sulfurization parameters for the conventional furnace and rapid thermal processing. Efforts were also taken to reduce the absorber thickness systematically and understand the issues involved with the thickness reduction. Experiments were carried out to study the effects of Na content on the surface morphology and the grain structure of the absorber film.
Venue	FSEC subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/07/2006

Post Date	01/08/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
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Author	J. R. Sites
Description	Alan Davies has been working closely with Sampath?s group, Al Enzenroth in particular, to explore buffer layers that would allow the CSU cells to be made with thinner CdS without compromising performance in other ways. Alan Fahrenbruch, also using CdTe cells fabricated by Sampath?s group, has examined transient effects related to photoconductivity and has related these to anomalous AQE effects. Ana Kanevce has added nonuniformities in diode voltage to her simulations of CIGS cells with submicron absorber layers. Several physical conditions (reduced local Ga concentration, reduced local thickness, reduced back electron reflector) can be well approximated by a weak diode with a lower value of VOC in the midst of an array of normal diodes. Ana also worked with Raghu Bhattacharya of NREL on the analysis of CIGS cells that that were fabricated with a solution-grown CdZnS buffer layer. The best of these cells achieved 19.5% efficiency, equal to that achieved with NREL?s standard CdS buffer. At short wavelengths, the CdZnS buffer did achieve about 2 mA/cm2 higher current than the CdS buffer, but it also had slightly less collection in the longer wavelength region.
Venue	Colorado State University, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/27/2006

Post Date	12/22/2006
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
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Author	L. Olsen
Description	No substrates with CdTe cell structures were received this quarter from CSU or UT. As a result, studies of photoluminescence in CdTe solar cell structures were initiated. The objective of this effort is to determine if the PL spectrum for a CdTe device is affected by stress. In particular, we are interested in determining if moisture affects carrier properties. Samples studied were cell structures without back contacts provided a year ago by CSU. The approach to the PL studies is described in Figure 1. An excitation wavelength of 580 nm was used and band gap emission observed for the excitation beam entering the through the glass and through the CdTe side.
Venue	PNNL, Memorandum Purchase Order ("subcontract") DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/2006

Post Date	12/20/2006
Title	UNIFORM, HIGH EFFICIENCY, HYBRID CIGS PROCESSING WITH APPLICATION TO NOVEL DEVICE STRUCTURES
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Author	A. E. Delahoy
Description	We have investigated the effects of changing the substrate temperature (Ts) for CIGS deposition on cell performance. The baseline Ts was set at 535�C. Lowering Ts could benefit large area module fabrication by avoiding substrate warping. We have been experimenting with two surface treatment techniques and we have achieved reproducible results with hundreds of CIGS test devices with related improvements in device parameters. Device test results achieved using these surface treatments are being reported herein. In Table III, device results from a freshly prepared 17" x 38" CIGS plate Z1817 are reported. The plate was prepared on 8/7/2006 and six 2" x 6" test samples were cut from it on 8/9/2006. Surface treatment-1 was applied before the standard CdS deposition process. Average device parameters Voc, FF, and efficiency etc. were measured.
Venue	EPV, subcontract ZXL-5-44205-05, quarterly report
Source	Energy Photovoltaics
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/2006

Post Date	11/21/2006
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURING ISSUES
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Author	R. W. Birkmire
Description	Issues associated with the thermal characteristics of the source boats and the effects of melt level reduction over time can negatively impact film quality and reproducibility. Specifically, difficulties encountered with the design of the sources presently in operation are addressed, and new designs are proposed that resolve the problem of thickness and composition uniformity over wider substrates (~12 inches). Simulation results are presented comparing the old source design with the proposed new one for a 12-inch wide substrate. It is shown that improved film thickness uniformity and hence, composition uniformity, is achieved with the proposed designs, and material utilization can be improved by an appropriate choice of system design parameters such as nozzle-to-substrate distance. The two-reaction selenization/sulfization of metallic Cu-In-Ga precursors is a commercially viable process for the manufacture of Cu(InGa)(SeS)2 films. In this work, the reaction pathways in single-reaction selenization and sulfization processes are studied, as well as composition profile development in two-reaction processes. Sputter-deposited precursor films were annealed at 450�C to characterize the starting intermetallic composition, or reacted in either H2Se or H2S at 450�C to observe changes in phase composition as the reaction progressed. The key observation was the formation of an initial Cu9(In0.64Ga0.36)4 intermetallic that is depleted incongruently to form Cu9Ga4 during selenization, and Cu16In9 during sulfization. In studying the two-reaction selenization/sulfization process, a 2 x 2 matrix of reaction times was examined. Samples were selenized for either 15 or 30 minutes at 450�C, followed by sulfization at 550�C for either 15 or 30 minutes. Samples selenized for 15 minutes exhibited uniform Ga through the depth of the film, while those selenized for 30 minutes exhibited the commonly observed back-contact Ga accumulation. In other work, the effect of precursor heat treatment on improving the uniformity of reacted Cu(InGa)(SeS)2 films has been studied.
Venue	Institute of Energy Conversion (IEC), subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/18/2006

Post Date	12/08/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spec-troscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. We could gather first results for Cu(In,Ga)Se2 (?CIGSe?) and Cu(In,Ga)(S,Se2) (?CIGSSe?) samples prepared by the group of W. Shafarman (Institute of Energy Conversion, University of Delaware). The aim of the conducted experiments is to shed light on the deeply buried absorber/back contact interface in terms of its chemical and electronic properties. We had to develop a suitable lift-off (or cleavage) technique, which allowed us to cleave the absorber/Mo/glass samples at the desired interface. It turned out that gluing the front side of the absorber/Mo/glass thin film stack to a stainless a steel plate using a conductive (Ag-containing) epoxy allows a subsequent division of the stack in two parts and provides the necessary conductivity for the PES measurements. In all cases the thin film stack cleaved at the absorber/Mo inter-face. However, there were differences in terms of the area exposed after lift-off. Compar-ing the CIGSe/Mo/glass and CIGSSe/Mo/glass samples with respect to their cleavage behavior, it seems that for the latter it is rather easy to lift off large areas (in the range of cm2). This is favorable with respect to the characterization by PES but even more impor-tant for the planned inverse photoemission (IPES) measurements, since the IPES detector is not able to ?artificially? reduce the spot size of the e-gun on the sample (which is approx. 1 cm^2) as it can easily be done in the PES case, probing differently sized areas by using different lens modes of the electron analyzer.
Venue	U. Nevada, Las Vegas, Subcontract No. XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/15/2006

Post Date	01/03/2008
Title	HIGH PRODUCTIVITY ANNEALING FOR THIN FILM CIS PV
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Author	C. Eberspacher
Description	Experiments designed to delineate the major processing parameters utilized a modified Jipelec JetFirst 150 rapid thermal processing system were carried out. The JetFirst system includes a cold wall reaction chamber, a quartz top-side window, and a 30 kW multi-zone halogen lamp source for rapid one-sided heating. The primary processing parameters in the JetFirst are temporal temperature profile (i.e. T(t)), total gas pressure, and gas composition; the secondary processing parameters include heating logistics (e.g. lamp spectrum, spatial uniformity, temporal stability, etc.).
Venue	Nanosolar Corp., subcontract ZXL-6-44205-15, quarterly report
Source	Nanosolar
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/15/2006

Post Date	12/20/2006
Title	HIGH PRODUCTIVITY ANNEALING FOR THIN FILM CIS PV
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Author	C. Eberspacher
Description	Scoping experiments designed to delineate the major processing parameters utilized a modified Jipelec JetFirst 150 rapid thermal processing system (Fig. 1). The JetFirst system includes a cold wall reaction chamber, a quartz top-side window, and a 30 kW multi-zone halogen lamp source for rapid one-sided heating.
Venue	NanoSolar, subcontract ZXL-5-44205-15, quarterly report
Source	Nanosolar
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2006

Post Date	10/11/2006
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
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Author	J. R. Sites
Description	We refined our preliminary work on CdTe voltage limitations, the primary issue for higher efficiencies, that was presented at the CdTe team meeting earlier in the year. The first question was why there is a 230-mV difference between the best CdTe voltages and the best GaAs when adjusted for band-gap difference, whereas the comparable difference between CIGS is only about 30 mV. The second question is how and whether this voltage difference can be significantly reduced without creating other difficulties. Success would translate into efficiencies above 20%. The answer to the first question is that current CdTe cells have a combination of low carrier density (~10^14 cm-3) and low absorber lifetime (generally below 1 ns). In some cases, the voltage is further compromised by the presence of a significant back-contact barrier. What numerical simulation has shown is that even large increases in lifetime alone will have only a minor impact on voltage. Earlier numerical simulations showed, under a variety of assumptions, including an effective back electron reflector, that progressive, uniform thinning of CIGS absorbers leads to lower values for all three J-V parameters, but there should not be a critical thickness at which there is a dramatic decrease. Since then we also explored back illumination of thin absorbers, and more lately, what can be expected when thin absorbers are not uniform. Ana Kanevce?s conclusion about front and back illumination is that the two responses will converge somewhat below 0.5 micron, as one would intuitively expect.eed to be a concurrent increase in carrier density to roughly the 10^17 range to approach GaAs voltages. Other priliminary findings were that the impact of non-uniformities is larger for thinner absorbers.
Venue	Colorado State University (Sites), Subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/31/2006

Post Date	07/21/2006
Title	PROCESSING, MATERIALS, DEVICES, AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
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Authors	R. W. Birkmire, W. N. Shafarman
Description	The report discusses melt-temperature profiles of evaporation sources and the effect on evaporation rates, the reaction chemistry of CIGS formed H2Se/H2S reaction, and characterization of thin CIGS layers for the development of CIGS cells with thin (<1 micrometer) absorber thicknesses.
Venue	Subcontract ADJ-1-30630-12, IEC, quarterly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/21/2006

Post Date	07/13/2006
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 42 KB)
Author	J. R. Sites
Description	During the past quarter, our group made progress in several areas as outlined below. Several of us participated actively in the CdTe and CIS team meetings. I made a trip to IEC in February to give a colloquium and discussion several topics of mutual interest. Adjacent to that visit, I attended to the DOE PV module-reliability meeting in Baltimore. I also participated (not at NREL expense) in the DOE?s SAI-input meeting that took place in Chicago in March. Our primarily work with industrial partners was LBIC measurements on Nanosolar cells and with assistance to Heliovolt in the design of current-voltage and quantum-efficiency measurement systems for their cells.
Venue	Quarterly Report V (February - April 2006) Subcontract XXL-5-44205-03 For additional information: www.physics.colostate.edu/groups/photovoltaic
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	07/2006

Post Date	12/20/2006
Title	UNIFORM, HIGH EFFICIENCY, HYBRID CIGS PROCESSING WITH APPLICATION TO NOVEL DEVICE STRUCTURES
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Author	A. E. Delahoy
Description	We explored deposition of CIGS of submicron thickness focusing on thicknesses around 0.5 ?m. The CIGS films were prepared using the simplified hybrid process. Table I summarizes the performance of our best cells at various CIGS thicknesses from 1.3 to 0.5 ?m. All devices had the same baseline structure of SLG/Mo/CIGS/CdS/i-ZnO/ZnO:Al. It is observed that device efficiency progressively drops from 13% to 10% as CIGS thickness decreases from 1.3 ?m to 0.5 ?m. We studied the effect of addition of iso-propyl alcohol in the chemical bath deposition of the buffer films CdS, ZnS, and (CdZn)S. We tried to follow the work of Bhattacharya et al. It was reported by Bhattacharya during the 2006 National CIS R&D Team Meeting that the i-ZnO layer could be omitted by use of a Cd:ZnS(O,OH) buffer layer. If this result could be repeatably achieved in the industry, it can eliminate the i-ZnO formation step before the P2 scribe, yielding a benefit in module production. Reactive-environment hollow cathode sputtering has been used to prepare TiN for use as a back contact material and ZnO:Al as a top TCO.
Venue	EPV, subcontract ZXL-5-44205-05, quarterly report
Source	Energy Photovoltaics
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/2006

Post Date	07/25/2006
Title	TRANSPORT, INTERFACES, AND MODELING IN AMORPHOUS SILICON BASED SOLAR CELLS
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Author	E. A. Schiff
Description	CIGS solar cells have two distinct regions. The top region, extending about 0.5 micron below the CdS/TCO interface, drops essentially all of the electric potential across the sample, and leads to capacitances which are larger than the geometrical capacitance of a typical, 2 micron thick cell. The back region, extending 1.5 ? 2 microns beneath the top region, has very little electric potential drop. For time-of-flight measurements, one usually tries to obtain sensitivity to the two photocarriers by using strongly absorbed top illumination for one carrier, and strongly absorbed back illumination for the second carrier. The same electric field polarity, corresponding to reverse biasing of the diode, is used for both experiments. This approach presumes that it is possible to create an essentially uniform electric field across the sample; pulsed voltage bias is usually used in time-of-flight experiments to help achieve this. This approach can't work in CIGS due to the very fast dielectric relaxation time of the back region of the cells. As an alternative, we tried switching from strongly absorbed top illumination (? = 700 nm) to more weakly absorbed top illumination (940 nm). This change actually required that we change nitrogen lasers (to a more powerful one) and purchase special infrared dyes. We do not have independent measurements of the absorption coefficient for our particular samples; some careful work by Alonso, et al. on CIGS with x = 0.2 indicates 50% absorption at depths of 0.1 �m (? = 700 nm) and about 0.3 �m (? = 940 nm). Our paper summarizing our device measurements and modeling for a-Si:H solar nip solar cells from United Solar, as a function of thickness and temperature, were published in January in Applied Physics Letters: J. Liang, E. A. Schiff, S. Guha, B. Yan, and J. Yang, Appl. Phys. Lett. 88 063512 (2006). DOI:10.1063/1.2170405 [.pdf]. While we are satisfied with the conclusion of this paper that the efficiency of as-deposited a-Si:H solar cells is dominated by hole mobility effects (i.e. not defects), the paper establishes what we view as a toolbox for exploring metastability using the modeling approach outlined in this paper.
Venue	Syracuse University, Subcontract NDJ-2-30630-24, quarterly report
Source	Syracuse University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/06/2006

Post Date	07/25/2006
Title	TRANSPORT, INTERFACES, AND MODELING IN AMORPHOUS SILICON BASED SOLAR CELLS
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Author	E. A. Schiff
Description	We continued our work on drift-mobility measurements in CIGS. As noted in previous reports, our hole drift-mobilities in CIGS are about 0.1 cm2/Vs, which is about 30-100 times lower than estimated using admittance measurements by Dave Cohen's group at Oregon. The distinction is very important for understanding solar cells; low-mobility solar cells are understood very differently than are high-mobility cells, and 1 cm2/Vs is about the dividing line between the two types of behavior. In this quarter we have begun to address this apparent discrepancy between the two groups' measurements. If we assume that both our measurements and those of Cohen's group are sound, then there are two physical differences that need to be considered as mechanisms for the difference. The first is a true difference between the samples; Cohen's group has worked primarily with samples from the Institute for Energy Conversion (IEC) at University of Delaware, and we have worked with samples from Noufi's group at NREL. The second is vertical inhomogeneity. We have been exploring the reasons for the fact that the saturation of the Staebler-Wronski effect generally occurs when the degradation of the optoelectronic properties has just become significant ? under solar illumination. The small decline of the open-circuit voltage in working a-Si:H solar cells under illumination is the best indicator of what we term "self-limiting" behavior. Presuming that defect creation is responsible for this degradation, self-limitation implies that the saturation defect density Nsat is comparable to the "crossover density" Ncrossover, where the latter is the defect density for which half of photocarrier recombination occurs at defect sites, and half at bandtail sites. We find that the equation Nsat ? Ncrossover provides a good account for intensity-dependence of Nsat (as reported by other groups). However, this relation predicts that Nsat should be smaller at elevated temperatures than has been reported; T-dependence of Nsat is fairly small.
Venue	Syracuse University, Subcontract NDJ-2-30630-24, quarterly report
Source	Syracuse University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/06/2006

Post Date	05/30/2006
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 87 KB)
Author	L. Olsen
Description	CdTe cell structures provided by CSU were stressed and then characterized with XPS in an effort to understand the effects of moisture on CdTe devices. If we assume the emission is primarily due to oxides on the grain boundaries, it appears that the unknown complex oxide could play a key role in grain boundary passivation. It could therefore be very valuable to determine the identity of this complex oxide. Based on results for the stressed cell, significant effects of the 60�C/90%RH stress may be formation of Cd(OH)2 along grain boundaries, and elimination of the unknown complex Cd-based oxide along the grain boundaries. If we assume that the unknown oxide is important for grain boundary passivation and/or the hydroxide results in increased recombination at grain boundaries, then it is understandable that both Jsc and Voc would decrease as a result of damp heat. We conclude, therefore, that damp heat does more than just degrade the contacts in CdTe cells. In particular, it appears that formation of Cd(OH)2 leads to increased recombination at grain boundaries, which decreases cell quantum efficiency and increases current losses (larger Jo).
Venue	1st Quarterly Report - Phase II: September 1, 2005 -- November 30, 2005 NREL Subcontract: 48027
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	05/2006

Post Date	06/12/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
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Authors	M. Baer, C. Heske
Description	Eight CdTe materials samples used in actual solar cell were investigated by X-ray emission spectroscopy (XES). This technique provides detailed informations about the chemical properties of the investigated samples. XES as a photon-in photon-out technique probes the ?near-surface? bulk. In our case, where we have focused on the S L2,3 and Cl L2,3 emission, this method has an information depth of about 100 nm. Based on the results obtained, we will continue the investigation of CdTe/CdS samples and extend them by investigating customized sample series with UPS and IPES to get insight into the band alignments at the various interfaces of the device structure of an CdTe-based solar cell. At the recent CdTe R&D team meeting (as well as at the CIS R&D team meeting) we have initiated a sample exchange with several (six) groups from within the Thin Film Photovoltaic Partnership Program. The planned experiments will shed light on the various interfaces in both CIS and CdTe cells. First samples have already been received at UNLV.
Venue	Subcontract XXL-5-44205-12, University Nevada, Las Vegas, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/15/2006

Post Date	06/01/2006
Title	TRANSPORT, INTERFACES, AND MODELING IN AMORPHOUS SILICON BASED SOLAR CELLS
Link	(MS Word 33 KB)
Author	E. A. Schiff
Description	Our measurements of the hole drift mobilities for two different CIGS depositions by Noufi's group at NREL, and involving many individual sets of contacts on a particular substrate for each deposition, give typical drift mobilities that are small (0.1 ? 0.5 cm2/Vs) and essentially temperature-independent. The temperature-independence is somewhat surprising to us; low drift-mobilities are often caused by traps which bind a photocarrier. Release from such a trap requires thermal excitation, and thus this mechanism gives a strong temperature-dependence to a drift-mobility. The conclusion of weak-temperature dependence for the hole drift-mobility was also reached in capacitance-based measurements by D. Cohen's group. Our manuscript to Applied Physics Letters describing our temperature-dependent solar cell measurements and modeling was accepted. The success of a fairly simple model, involving only bandtail states for as-deposited a-Si:H, has led us to conclude that light-soaking is essentially a "perturbation" of the properties under illumination of the as-deposited state. The hallmark of this statement is the fact that open-circuit voltages decline only quite modestly (perhaps 5%) between the as-deposited and light-soaked states for contemporary a-Si:H solar cells at the light-soaking temperature.
Venue	Subcontract NDJ-2-30630-24, Syracuse University, quarterly report
Source	Syracuse University
Document Type	Quarterly Report (Word document)
Resource Date	03/29/2006

Post Date	05/02/2006
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	This report documents what we have learned from a set of high performance NREL CIGS devices that were obtained in July, 2005, from Miguel Contreras, comparing the results of our measurements on NREL devices with varying levels of performance. We obtained three samples, each containing 6 devices, with average efficiencies in the 14-15% range (C1919-11), in the 16-17% range (C1818-21), and in the 17-18% range (C1924-1). Among the total of 18 devices, 4 or 5 seemed anomalous (primarily because of low shunt resistances) and we selected 8 of the remaining devices for detailed study that seemed to represent a good range of performance parameters. Drive-level capacitance profiles (DLCP) and CV profiles for representative devices were taken over a broad range of temperatures. The results of these measurements are discussed.
Venue
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/13/2006

Post Date	09/18/2006
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
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Author	N. G. Dhere
Description	During this quarter, experiments were carried out to optimize the metallic precursor deposition for standard and very thin absorber preparation and selenization/sulfurization parameters for the conventional furnace and rapid thermal processing. Also maintenance of two cryopumps was completed and maintenance of diffusion pump was carried out. The two cryopumps are used to obtain high vacuum in sputtering systems while the diffusion pump is used for obtaining high vacuum in the vacuum evaporation system.
Venue	Florida Solar Energy Center, subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/08/2006

Post Date	02/28/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 99 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission spectroscopy) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as the chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In our recent beamtime at the Advanced Light Source, Lawrence Berkeley National Laboratory we collected first results with Cu(In,Ga)Se2 samples prepared by NREL. Together with additional photoemission measurements a detailed picture of the chemical composition at several interfaces and surfaces of the device structure can be drawn. The setup for inverse photoemission at UNLV was commissioned and first spectra were recorded.
Venue	U. Nevada, Las Vegas, subcontract XXL-5-44205-12, 2nd Quarterly Report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/18/2006

Post Date	01/25/2006
Title	CUINSE2 BASED SOLAR CELLS
Link	(PDF 2.2 MB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	Thermal Modeling of Linear Source, Wide Bandgap Materials: Cu(InAl)Se2 Formation by H2Se/H2S Fundamental Materials and Interface Characterization
Venue	Subcontract #ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/18/2006

Post Date	01/13/2006
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
Link	(MS Word 4.8 MB)
Author	N. G. Dhere
Description	In the Year 1, First Quarter report, initial experiments towards optimizing the selenization parameters were discussed in detail. During this quarter the experiments were continued using both conventional and rapid thermal processing approaches. In the following discussion, the preparation and the characterization of CuIn1-xGaxSe2 and CuIn1-xGaxS2 thin films and solar cells are discussed in detail. A state-of-the-art CuInGaS2 cell with open-circuit voltage of 830 mV was obtained.
Venue	FSEC ubcontract XXL-4-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	12/19/2005

Post Date	12/16/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 45 KB)
Author	J. R. Sites
Description	CdTe Device Model; Cu in the Back Contact;Back-Illuminated LBIC; CdTe Photoluminescence; CIGS Thin Absorbers/Back Lighting; Effective Module Efficiency The two key module parameters that control the effective efficiency are the series resistance and leakage conductance of the module; (1) ?Grain-Boundary Recombination in Cu(In,Ga)Se2 Solar Cells,? J. Appl. Phys. 98, 113704, 10 pp (2005). M. Gloeckler, W.K. Metzger, and J.R. Sites. (2) ?Potential of Sub-micrometer Thickness Cu(In,Ga)Se2 Solar Cells,? J. Appl. Phys. 98, 103703, 7 pp (2005). M. Gloeckler and J.R. Sites.
Venue	Subcontract XXL-5-44205-03 Quarterly Report IV (September - November 2005); : http://www.physics.colostate.edu/groups/photovoltaic
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	12/15/2005

Post Date	12/05/2005
Title	SI-BASED SOLAR CELLS
Link	(PDF 5.6 MB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	In the monthly report for March 2005, a design of experiment (DOE) approach was described to continue the study of aluminum induced crystallization (AIC) of Al-Si bilayers. A matrix of samples was created to investigate key variables that had been identified by previous AIC studies at IEC. We are looking for the effect of different structures (normal and reverse), different annealing temperature (above and below eutectic), and annealing time on AIC. The experiments were designed to evaluate the effects of 3 factors on AIC as shown in Table I. The performance of a well-designed co-evaporative physical vapor deposition process for CIGS thin-film growth depends mainly on the ease of controlling individual elemental vapor fluxes. This is done essentially by manipulating the individual source-boat temperature set-points provided by a model predictive controller to achieve the desired film thickness and composition. In such a cascaded control structure, fast and accurate inner-loop controllers are essential. The popular PID controllers are usually employed to control the inner temperature loops.
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/2005

Post Date	10/21/2005
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 414 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance.
Venue	subcontract quarterly report, U. Nevada, Las Vegas, XXL-5-44205-12
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/13/2005

Post Date	09/13/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 44 KB)
Author	J. R. Sites
Description	During the past quarter, we made progress in several areas as outlined below. I am particularly pleased that the two students who completed their PhD this year have accepted R&D positions in the US thin-film photovoltaic industry. Alex Pudov starts at Nanosolar in Palo Alto this week, and Markus Gloeckler will be joining First Solar in Toledo in early October.
Venue	Quarterly Report III (June - August 2005) Subcontract XXL-5-44205-03
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	09/12/2005

Post Date	09/27/2005
Title	CUINSE2 BASED SOLAR CELLS
Link	(PDF 838 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	During the present reporting period, the focus was on the two specific issues that must be resolved for a successful commercial-scale development: (1) melt-temperature gradients, and (2) the reduction of melt-level with time. Considering how these issues arise from elemental source design, and considering their impact on process controllability, the scale-up issues can be divided into the following two components: (1) The design issue ? where an elemental source is designed such that melt-temperature gradients are minimized, thus reducing product quality variations, and (2) The control issue ? where the mean values of the final film quality variables are robustly controlled such that the desired set-points are achieved while simultaneously rejecting the disturbances introduced by the melt-level reduction.
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/09/2005

Post Date	09/13/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 64 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	CdZnTe and CIGS alloys
Venue	XAT-4-33624-01 6th Quarterly Report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2005

Post Date	09/09/2005
Title	HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS
Link	(MS Word 1.0 MB)
Author	N. G. Dhere
Description	Various selenization/sulfurization were carried out and the resulting films were characterized. A detailed study was carried out to understand the necessity of thinner CIGSS absorber layers through the ?Terawatt Challenge? and the indium cost. Initial experiments were carried out to achieve 1 �m thick CIGSS absorber layer. The absorber layer was studied through materials characterization techniques such as scanning electron microscopy (SEM) for morphology, X-ray energy dispersive spectroscopy (XEDS) for composition, secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) for depth profile and X-ray diffraction (XRD) for the structure. CuGa-In metallic precursors were selenized using dilute diethylselenide (DESe) as selenium source at 400�C for 10 minutes and further sulfurized using dilute H2S as sulfur source at 475�C for 20 minutes.
Venue	subcontract XXL-5-44205-08, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	08/19/2005

Post Date	08/31/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUINXGA1-XSE2
Link	(PDF 325 KB) Download Acrobat Reader.
Author	C. S. Ferekides
Description	quarter of Phase III of the above subcontract. The project deals with two thin film technologies: CdTe and CIGS. The focus areas include: (a) CdTe ? stability, novel back/front contacts, and the development of manufacturing friendly processes; (b) CIGS ? development of two-step non-co-evaporation technology.This is the progress report for the 3rd
Venue	NDJ-2-30630-18 Phase III/Quarter 3
Source	University of South Florida, Tampa
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2005

Post Date	08/31/2005
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 529 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov
Description	During this quarter we worked on ellipsometric diagnostics, device physics modeling and thin CdTe solar cell limitations. In this report we highlight our recent results on real-time spectroscopic ellipsometry studies of rf-sputtered solar cells (task 1.3.2) and quantitative estimates of nonuniformity loss in solar cell modules, including the effect of series resistance.
Venue	RXL-5-44205-01 Phase 1/Quarter 1
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2005

Post Date	06/14/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 46 KB)
Author	J. R. Sites
Description	During the past quarter, we reported a number of results at both the Materials Research Society Spring Meeting in late March and the CdTe National Team Meeting in early May. Most of the manuscripts or powerpoint slides from these and other presentations are available on our web site: www.physics.colostate.edu/groups/photovoltaic In addition, Markus Gloeckler recently completed his PhD degree. His thesis, which is both attached and on the web page, contains a more extensive description of his work on CIGS grain boundaries, grading effects, and efficiency limitations than that published or submitted for publication.
Venue	Quarterly Report II (March - May 2005) Subcontract XXL-5-44205-03
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	06/13/2005

Post Date	07/26/2005
Title	TOLERANCE OF THREE STAGE CIGS DEPOSITION TO VARIATIONS IMPOSED BY ROLL-TO-ROLL PROCESSING
Link	(MS Word 368 KB)
Authors	M. E. Beck, J. S. Britt
Description	1. Setting up the National Renewable Energy Laboratory (NREL)-developed three-stage CIGS laboratory process in a bell jar. 2. Characterizing the GSE roll-to-roll production chambers and device finishing steps in terms of the variables important to the laboratory processes. 3. Using the bell jar system to step incrementally from the NREL process to the conditions experienced by a sample during manufacturing, and characterizing the resulting films and devices. Applying the process sensitivity information gained from the bell jar system to the production systems.
Venue	Phase III, Fourth Quarterly Report #ZDJ-2-30630-14
Source	Global Solar
Document Type	Quarterly Report (Word document)
Resource Date	05/23/2005

Post Date	06/10/2005
Title	CUINSE2-BASED SOLAR CELLS
Link	(PDF 1.2 MB) Download Acrobat Reader.
Author	R. W. Birkmire
Description
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/2005

Post Date	08/04/2005
Title	LAB TO LARGE SCALE? TRANSITION FOR NON-VACUUM THIN FILM CIGS SOLAR CELLS
Link	(MS Word 2.3 MB)
Authors	A. Bansal, V. K. Kapur
Description	The goal of this contract is to identify the challenges faced by ISET in scaling up its non-vacuum process from a laboratory to large scale manufacturing and to develop workable solutions for these challenges such that they can be readily implemented in large scale processing of CIGS solar cells and modules. In phase III (3^rd year) of this 3-year contract, ISET is focusing on i) further improvement in cell efficiency, ii) evaluation of alternate deposition techniques for coating ISET?s inks uniformly on large area substrates, iii) developing monolithic integration schemes for making CIGS modules on glass substrates and iv) increasing material?s usage and minimizing waste.
Venue	NREL Subcontract # XCQ-230630-30
Source	ISET
Document Type	Quarterly Report (Word document)
Resource Date	04/30/2005

Post Date	04/19/2005
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 1.8 MB)
Author	N. G. Dhere
Description	A Rapid Thermal Processing (RTP) unit has been designed, constructed and installed for preparation of CIGSS thin films on 10 cm x 15 cm substrates by selenization/ sulfurization of elemental precursors using the vacuum deposited selenium layer and N2:H2S atmosphere. For RTP, selenium evaporation will be carried out by thermal evaporation in a separate setup. An optimized, minute amount of NaF will be added to improve the morphological and electrical properties of the absorber.
Venue	Subcontract NDJ-2-30630-03, quarterly report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	04/19/2005

Post Date	05/22/2006
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 1.8 MB)
Author	N. G. Dhere
Description	A Rapid Thermal Processing (RTP) unit has been designed, constructed and installed for preparation of CIGSS thin films on 10 cm x 15 cm substrates by selenization/ sulfurization of elemental precursors using the vacuum deposited selenium layer and N2:H2S atmosphere. For RTP, selenium evaporation will be carried out by thermal evaporation in a separate setup. An optimized, minute amount of NaF will be added to improve the morphological and electrical properties of the absorber.
Venue	NDJ-2-30630-03 Year 4, Quarter 2 Report
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	04/18/2005

Post Date	05/13/2005
Title	THIN FILM CENTER OF EXCELLENCE
Link	(PDF 1.3 MB) Download Acrobat Reader.
Authors	R. W. Birkmire, W. N. Shafarman
Description	This report covers research conducted at the Institute of Energy Conversion (IEC) for the period of Jan. 09, 2005 to Feb. 09, 2005, under the subject subcontract. The report highlights progress and results obtained under Task 2 (CuInSe2).
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2005

Post Date	03/22/2005
Title	QUARTERLY REPORT I (DECEMBER 2004 - FEBRUARY 2005) "CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS" SUBCONTRACT XXL-5-44205-03
Link	(MS Word 39 KB)
Author	J. R. Sites
Description	CIGS grain boundaries; thins CIGS grading; secondary CIGS junction barriers; Alternative junctions with CIGS; Cdte Cell Operation, LBIC Studies, PL Studies
Venue
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/21/2005

Post Date	05/09/2005
Title	TRANSPORT, INTERFACES, AND MODELING IN AMORPHOUS SILICON BASED SOLAR CELLS
Link	(MS Word 33 KB)
Author	E. A. Schiff
Description	The main work during this quarter has been on a-Si:H solar cell characterization & modeling, and in particular on the time-dependence of the degradation of the open-circuit voltage. We have been fairly successful in accounting for the measurements of the time-dependence of degradation with an elementary model. Additional, rather interesting results emerged from measurements of hole drift-mobilities in CIGS. The hole drift-mobility appears rather low (less than 0.1 cm2/Vs), and nearly temperature-independent. If these results are confirmed, they would indicate that CIGS solar cells are actually low-mobility cells and possibly mobility-limited. Finally, we have found a good tool for exploring VOC in a-Si:H and c-Si solar cells with polymer p-layers, and are exploring VOC as a function of the resistivity of the polymer layer.
Venue	subcontract NDJ-2-30630-24, quarterly report
Source	Syracuse University
Document Type	Quarterly Report (Word document)
Resource Date	02/10/2005

Post Date	04/15/2005
Title	?LAB TO LARGE SCALE? TRANSITION FOR NON-VACUUM THIN FILM CIGS SOLAR CELLS
Link	(MS Word 151 KB)
Authors	A. Bansal, V. K. Kapur
Description	ISET is focusing on i) further improvement in cell efficiency, ii) evaluation of alternate deposition techniques for coating ISET?s inks uniformly on large area substrates, iii) developing monolithic integration schemes for making CIGS modules on glass substrates and iv) increasing material?s usage and minimizing waste.
Venue	subcontract XCQ-2-30630-30 quarterly report
Source	ISET
Document Type	Quarterly Report (Word document)
Resource Date	01/31/2005

Post Date	02/14/2005
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 1.8 MB)
Author	N. G. Dhere
Description	CuIn1-xGaxSe2-ySy (CIGSS) thin films were prepared at the FSEC photovoltaic materials lab in two steps. The first step consisted of deposition of CuGa-In precursors using DC magnetron sputtering on molybdenum back contact. The second step involved selenization/sulfurization of these precursors. Selenization and sulfurization were carried out using diethylselenide (DESe) as a selenium source and H2S as sulfur source. Selenization was carried out at 400°C for 10 minutes in diluted DESe followed by sulfurization at 475°C for 20 minutes in diluted H2S.
Venue	NREL contract no. NDJ-2-30630-03, UCF/FSEC
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	01/14/2005

Post Date	03/07/2005
Title	ADVANCED CIGS PHOTOVOLTAIC TECHNOLOGY
Link	(PDF 394 KB) Download Acrobat Reader.
Author	A. E. Delahoy
Description	The main areas concerned: 1) CIGS absorber and device optimization 2) Cu selenization experiments 3) Front and back contacts 4) Surface treatment and annealing 5) Background work for sub-micron device and module 6) Hercules sources
Venue	RDJ-2- 30630-21 9/1/04 ? 11/30/04.
Source	Energy Photovoltaics
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/14/2004

Post Date	03/04/2005
Title	SECOND QUARTERLY REPORT
Link	(PDF 260 KB) Download Acrobat Reader.
Author	M. E. Beck
Description	Two-stage and three-stage CIGS coevaporation - followed by chemical bath CdS and RF-sputtered resistive and conductive ZnO - have come to be viewed as laboratory standards for the deposition of CIGS photovoltaic devices. However, a number of conditions are encountered during continuous manufacturing that prevent an exact replication of the laboratory processes. Such differences include both those imposed by continuous processing of moving substrates, and those implemented to decrease costs and increase throughput. It is, therefore, beneficial to understand the tolerance of the established laboratory processes to variations in deposition procedures.
Venue	ZDJ-2-30630-14.
Source	Global Solar
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/15/2004

Post Date	02/17/2005
Title	LIQUID-PHASE DEPOSITION OF ALPHA-CIS THIN LAYERS
Link	(PDF 1.1 MB) Download Acrobat Reader.
Authors	F. Ernst, P. Pirouz
Description	We have focused on further developing the liquid-phase deposition technique in order to grow thinner layers and achieve better uniformity of the layer thickness. Apparently, the excessive thickness and roughness of the layers we deposited with the first-generation apparatus arose because the frozen material was able to lift the sliding boat.
Venue	Subcontract XDJ-3-30630-33, Case Western
Source	Case Western
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/12/2004

Post Date	03/03/2005
Title	PROCESS R&D FOR CIS-BASED THIN-FILM PV
Link	(MS Word 3.5 MB)
Author	D. E. Tarrant
Description	Quarterly Technical Status Report, August through October 2004
Venue
Source	Shell Solar Industries
Document Type	Quarterly Report (Word document)
Resource Date	11/2004

Post Date	03/03/2005
Title	THE ELECTRONIC PROPERTIES RELEVANT TO IMPROVING THE PERFORMANCE OF HIGH BAND-GAP COPPER BASED I-III-V12 CHALCOPYRITE THIN FILM PHOTOVOLTAIC DEVICES
Link	(PDF 558 KB) Download Acrobat Reader.
Author	J. D. Cohen
Description
Venue	XAT-4-33624-08
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 30 KB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	09/07/2004

Post Date	03/04/2005
Title	ADVANCED CIGS PHOTOVOLTAIC TECHNOLOGY
Link	(MS Word 4.7 MB)
Author	A. E. Delahoy
Description	This report summarizes the main activities conducted in this quarter (Q3), concluding with plans and other news. It will be recalled that the Q2 highlight was a 7.5% 26W module verified by NREL. The highlight of this quarter is a 13.1% cell verified by NREL. 1) Device optimization 2) Cell performance vs. i-ZnO conductivity 3) Uniformity improvement for large area plate 4) Outdoor sub-module stability 5) Overall progress with hybrid process 6) New types of TCO
Venue	RDJ-2-30630-21
Source	N/A
Document Type	Quarterly Report (Word document)
Resource Date	09/06/2004

Post Date	03/03/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 856 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description
Venue	XAT-4-33624-01
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2004

Post Date	02/17/2005
Title	LIQUID-PHASE DEPOSITION OF ALPHA-CIS THIN LAYERS
Link	(PDF 149 KB) Download Acrobat Reader.
Authors	F. Ernst, P. Pirouz
Description	We have made significant advances in the area of TEM sample preparation and in characterization of deposited Cu?In?Se films via TEM. In this report we will show that we have successfully deposited a thin layer with coarse grain sizes of alpha-CIS.
Venue	Subcontract XDJ-3-30630-33, Case Western
Source	Case Western
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/12/2004

Post Date	03/03/2005
Title	QUARTERLY TECHNICAL STATUS REPORT, MAY THROUGH JULY 2004; PROCESS R&D FOR CIS-BASED THIN-FILM PV
Link	(MS Word 489 KB)
Author	D. E. Tarrant
Description
Venue	ZDJ-2-30630-16
Source	Shell Solar Industries
Document Type	Quarterly Report (Word document)
Resource Date	08/2004

Post Date	02/16/2005
Title	FUNDAMENTAL MATERIALS RESEARCH AND ADVANCED PROCESS DEVELOPMENT FOR THIN-FILM CIS-BASED PHOTOVOLTAICS
Link	(PDF 3.9 MB) Download Acrobat Reader.
Authors	T. J. Anderson, V. Craciun, O. D. Crisalle, S. S. Li
Description	The Cu-In/Mo/glass and Cu-In/glass precursors were prepared using the PMEE (Plasmaassisted Migration Enhanced Epitaxy) reactor. During the deposition of elemental copper and indium, the substrates were not heated to minimize the possible reaction between copper and indium. The atomic composition ([Cu]/[Ga]~1.0) of as-grown precursor was determined by ICP. The effects of PLA treatment on the film properties and the performance of CIGS solar cells have been studied by us under various annealing conditions. The growth of CIGS absorber films to study alternative buffer layers has been delayed. Approximately ten growth runs were completed before the gallium source started to malfunction. Cross-sectional TEM was used to view the morphology and the crystal structure of sample CIS3 coated with Pt. Transmission electron microscopy-Energy dispersive X-ray spectroscopy (TEM-EDX) was also used to determine the location of Cu-Se secondary phase. CBD-ZnxCd1-xS buffer layers were characterized. Target treatment (sputter ZnO deposition) with an Ar and oxygen mixture was also attempted and non-reactive sputtering was used after the treatment. It was found that if the sputtering conditions are controlled in a certain region, non-reactive sputtering after target treatment can also yield highly transparent films. Changing the sputtering conditions changes the transmission. It was also found that under certain working pressure, if the deposition power goes beyond a value, the films become metal rich again and target treatment is required to regain transparent films.
Venue	Subcontract ADJ-2-30630, University of Florida
Source	University of Florida, Gainesville
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/01/2004

Post Date	02/16/2005
Title	IDENTIFYING THE ELECTRONIC PROPERTIES RELEVANT TO IMPROVING THE PERFORMANCE OF HIGH BAND-GAP COPPER BASED I-III-V1 CHALCOPYRITE THIN FILM PHOTOVOLTAIC DEVICES
Link	(PDF 441 KB) Download Acrobat Reader.
Author	J. D. Cohen
Description	As a prelude toward applying modulated photocurrent (MPC) methods to the higher bandgap CIS alloys in hopes of identifying minority carrier trapping processes, we have carried out high frequency admittance measurements of CIGS samples to measure the dielectric relaxation times as a function of temperature. These measurements have turned out to be valuable in themselves, since they have allowed us to determine the hole carrier mobilities directly in working CIGS solar cell...
Venue	XAT-4-33624-08
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/2004

Post Date	03/03/2005
Title	IEC CIS TASK
Link	(PDF 444 KB) Download Acrobat Reader.
Author	W. N. Shafarman
Description
Venue	#ADJ-1-30630-12 June 09, 2004 to July 09, 2004
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/2004

Post Date	02/14/2005
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 1.2 MB)
Author	N. G. Dhere
Description	CIGS2/CdS thin film solar cells were routinely prepared on stainless steel foil and molybdenum coated glass substrates. A new selenization set-up using diethylselenide (DESe) as selenium source was commissioned. Preliminary experiments for selenization were carried out. X-ray diffraction and electron probe microanalysis have shown promising results. Rapid thermal processing set-up is also being assembled.
Venue	NREL contract no. NDJ-2-30630-03, UCF/FSEC
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	06/21/2004

Post Date	02/14/2005
Title	UNDERSTANDING THE STRUCTURAL AND CHEMICAL BASIS OF CHALCOPYRITE SOLAR CELL OPERATION
Link	(MS Word 244 KB)
Author	A. Rockett
Description	IEC has now provided a fourth sample that was grown at low temperature by the uniform process (sample 4). This report focuses on sample 4. We have completed preparation of both plan-view and cross-sectional samples and the results are as follows...
Venue
Source	University of Illinois
Document Type	Quarterly Report (Word document)
Resource Date	06/2004

Post Date	02/14/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 42 KB)
Author	L. Olsen
Description	Four 6 cm x 6 cm circuits were coated with a single, thick polymer layer to possibly act as a barrier coating and sent to SSI. The coating was deposited as requested by SSI. SSI plans to subject these circuits to much less stringent testing than normally used for qualification.
Venue	3rd Quarterly Report - Phase II: March 1, 2004 — May 31, 2004
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	06/2004

Post Date	02/17/2005
Title	LIQUID-PHASE DEPOSITION OF ALPHA-CIS TIN LAYERS
Link	(PDF 232 KB) Download Acrobat Reader.
Authors	F. Ernst, P. Pirouz
Description	We have deposited Cu?In?Se films by utilizing the "sliding boat" technique, as previously described. The newly adopted technique has proven to work very well in depositing Cu?In?Se films from the melt. For all films deposited so far, the chemical composition of the starting ingot material has been Cu_33.3In_33.3Se_33.3.
Venue	Subcontract XDJ-3-33630-33, Case Western
Source	Case Western
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/11/2004

Post Date	02/09/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 700 KB) Download Acrobat Reader.
Author	N/A
Description	Much of the work this quarter continued to focus on the relative incorporation of S and Se during CuIn(SeS)₂ or Cu(InGa)(SeS)₂ deposition. In the previous quarterly report, we showed that the re was a reproducible difference between films grown with Cu-rich composition and those with Cu-poor composition. Films deposited with Cu/(In+Ga) > 1.1 preferentially incorporate S, while those with Cu/(In+Ga) < 0.9 preferentially incorporate Se. This is shown in Figure 1, which plots the relative S and Se incorporation in films, as measured by EDS, as a function of the S/(S+Se) ratio in the vapor, determined by the average effusion rate measured for each source during the run. For both the Cu-rich and Cu-poor cases, there is no correlation with Ga/(In+Ga) and data is included for CuIn(SeS)₂ films as well as Cu(InGa)(SeS)₂ with different Ga/(In+Ga). Post-deposition KCN etching, to remove a surface Cu_x (SeS)_y...
Venue	2nd Quarterly Report XAT-4-33624-01
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/05/2004

Post Date	02/14/2005
Title	CIGSS THIN FILM SOLAR CELLS
Link	(MS Word 48 KB)
Author	N. G. Dhere
Description	CIGS2/CdS thin film solar cells were routinely prepared on stainless steel foil and molybdenum coated glass substrates. XY sweep controller circuit has been received back from manufacturer after a minor repair. The controller was installed and e-beam system is now fully operational. A minor improvement has been carried out in the mechanism for holding and rotating one complete 4" x 4" substrate.
Venue	NREL contract no. NDJ-2-30630-03, UCF/FSEC
Source	FLorida Solar Energy Center
Document Type	Quarterly Report (Word document)
Resource Date	04/26/2004

Post Date	03/04/2005
Title	PROCESS R&D FOR CIS-BASED THIN-FILM PV
Link	(MS Word 2.8 MB)
Author	D. E. Tarrant
Description	CIGS
Venue	ZDJ23063016 Quarterly Technical Status Report, February through April 2004
Source	Shell Solar Industries
Document Type	Quarterly Report (Word document)
Resource Date	04/08/2004

Post Date	02/16/2005
Title	FUNDAMENTAL MATERIALS RESEARCH AND ADVANCED PROCESS DEVELOPMENT FOR THIN-FILM CIS-BASED PHOTOVOLTAICS
Link	(PDF 954 KB) Download Acrobat Reader.
Authors	T. J. Anderson, V. Craciun, O. D. Crisalle, S. S. Li
Description	Bi-layer GaSe/CuSe precursor films were grown on sodium-free thin (0.4mm) glass substrates in the PMEE (Plasma-assisted Migration Enhanced Epitaxy) reactor. During this quarter, dark- J-V and DLTS measurements have been carried out to study the effect of Non-melt Laser annealing (NLA) treatment on CIGS cells in more detail. An extensive growth plan for CIGS absorber films has been developed to study alternative buffer layers. A maximum of nine substrates can be loaded into the plasma-assisted migration enhanced epitaxy (PMEE) reactor. Efforts on preparing the recipes, chemicals, and deposition conditions were undertaken. ZnO sputter deposition was held up because of required repairs to the sputter deposition system. For alternative buffer layers using (Cd,Zn)S, ZnS...
Venue	Subcontract ADJ-2-30630-13, University of Florida
Source	University of Florida, Gainesville
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/01/2004

Post Date	03/03/2005
Title	CIS TASK
Link	(PDF 182 KB) Download Acrobat Reader.
Author	W. N. Shafarman
Description
Venue	#ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2004

Post Date	03/04/2005
Title	LAB TO LARGE SCALE TRANSITION FOR NON-VACUUM THIN FILM CIGS SOLAR CELLS
Link	(MS Word 254 KB)
Author	V. K. Kapur
Description
Venue	XCQ-230630-30
Source	ISET
Document Type	Quarterly Report (Word document)
Resource Date	04/2004

Post Date	03/04/2005
Title	ADVANCED CIGS PHOTOVOLTAIC TECHNOLOGY
Link	(PDF 249 KB) Download Acrobat Reader.
Author	A. E. Delahoy
Description	Almost all of the activities were associated with the production of large area CIGS modules in the pilot line, and their analysis. 1) Installation of full size dipping tanks for CBD CdS. 2) Investigation and solution of contact resistance problems. 3) Improvement of ZnO properties. 4) Development of all face-up patterning. 5) Large area module performance and analysis. 6) Extrinsic supply of sodium.
Venue	RDJ-2-30630- 21
Source	Energy Photovoltaics
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/18/2004

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 35 KB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/05/2004

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 35 KB)
Author	J. R. Sites
Description	Measurement and analysis.
Venue	NREL Q10 ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/05/2004

Post Date	02/16/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 219 KB)
Author	L. Olsen
Description	Stressing CIS cells under humidity
Venue	2nd Quarterly Report - Phase II: December 1, 2003 — February 29, 2004
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	03/2004

Post Date	03/04/2005
Title	GLOBAL SOLAR
Link	(PDF 392 KB) Download Acrobat Reader.
Author	M. E. Beck
Description	Setting up the National Renewable Energy Laboratory (NREL)-developed three-stage CIGS laboratory process in a bell jar. 2. Characterizing the GSE roll-to-roll production chambers and device finishing steps in terms of the variables important to the laboratory processes. 3. Using the bell jar system to step incrementally from the NREL process to the conditions experienced by a sample during manufacturing, and characterizing the resulting films and devices.
Venue	Phase II, Third Quarterly Report #ZDJ-2-30630-14
Source	Global Solar
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/26/2004

Post Date	03/04/2005
Title	CIS
Link	(PDF 951 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	CIS
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	02/04/2004