 |
Latest Updates
Below are the ten most recent resources that we have received. They are sorted according to posting date. Author information, full title, a brief description, and other details are also included.
These ten resources are also posted in the appropriate individual technology section.
| Post Date | 07/12/2008 |
|---|
| Technology | Copper Indium Diselenide |
|---|
| Title | INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE |
|---|
| Link | (PDF 334 KB) Download Acrobat Reader. |
|---|
| 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 | 07/09/2008 |
|---|
| Technologies | Amorphous and Thin Film Silicon, Cadmium Telluride, Copper Indium Diselenide |
|---|
| 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 | 07/09/2008 |
|---|
| Technologies | Cadmium Telluride, Copper Indium Diselenide |
|---|
| Title | CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS" |
|---|
| Link | (PDF 123 KB) Download Acrobat Reader. |
|---|
| 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 |
|---|
| Technology | Copper Indium Diselenide |
|---|
| Title | HIGH THROUGHPUT, LOW TOXIC PROCESSING OF VERY THIN, HIGH EFFICIENCY CIGSS SOLAR CELLS |
|---|
| Link | (PDF 2.2 MB) Download Acrobat Reader. |
|---|
| 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 | 05/30/2008 |
|---|
| Technologies | Amorphous and Thin Film Silicon, Cadmium Telluride, Copper Indium Diselenide, General Interest |
|---|
| 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 | 05/27/2008 |
|---|
| Technology | Amorphous and Thin Film Silicon |
|---|
| Title | HIGH-EFFICIENCY AMORPHOUS SILICON AND NANOCRYSTALLINE SILICON-BASED SOLAR CELLS AND MODULES |
|---|
| Link | (PDF 2.5 MB) Download Acrobat Reader. |
|---|
| Authors | S. Guha, J. Yang |
|---|
| Description | United Solar Ovonic LLC successfully used its spectrum-splitting a-Si:H/a-SiGe:H/a-SiGe:H triple-junction structure in their manufacturing plants, achieving manufacturing capacity of 118 MW in 2007 from its Auburn Hills and Greenville, Michigan plants. United Solar has a very aggressive expansion plan to achieve grid parity by improving its solar panel efficiency, improving manufacturing throughput, and reducing manufacturing cost. In the Thin Film Partnership Program, Uni-Solar identified three areas of research: i) Optimize a-Si:H and a-SiGe:H deposition parameters under the current manufacturing constraints for improving solar module efficiency and manufacturing throughput, and reducing the manufacturing cost; ii) Explore new deposition methods for a-Si:H and a-SiGe:H materials to improve a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cell efficiency at high deposition rates; and iii) Explore new materials and new cell structures for higher efficiency at high deposition rates. |
|---|
| Venue | United Solar Ovonic LLC, subcontract ZXL-6-44205-14, Final Report |
|---|
| Source | Uni-Solar Ovonic |
|---|
| Document Type | Final Report (Adobe Postscript file) |
|---|
| Resource Date | 05/2008 |
|---|
|
| Post Date | 05/01/2008 |
|---|
| Technology | Amorphous and Thin Film Silicon |
|---|
| Title | PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN-FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURING ISSUES |
|---|
| Link | (PDF 404 KB) Download Acrobat Reader. |
|---|
| Author | R. W. Birkmire |
|---|
| Description | High efficiency Si solar cells require a textured surface with an anti-reflection layer, to reduce reflection and increase light trapping, and a well-passivated surface, to reduce recombination and increase VOC. The three processing sequences must be integrated together and be compatible with one another to achieve the full benefits. This section covers work performed at IEC to develop inverted pyramidal texturing on a planar (100) FZ wafer, followed by chemical cleaning of the surface and low temperature passivation.
The process of inverted texturing developed at IEC is as follows:
1. PECVD deposition of 20nm SiN sacrificial layer
2. Photoresistor is applied and pattern is defined by mask
3. Patterning using photolithography
4. 60s 1:9 buffered oxide etch (BOE) etching SiN to open texturing window and exposure of Si surface
5. 30% KOH solution with 2%IPA @ 50 degrees textures surface and gets desirable pattern |
|---|
| Venue | Institute of Energy Conversion (IEC, U. Delaware), subcontract ADJ-1-30630-12, monthly report |
|---|
| Source | University of Delaware |
|---|
| Document Type | Quarterly Report (Adobe Postscript file) |
|---|
| Resource Date | 04/18/2008 |
|---|
|
| Post Date | 05/01/2008 |
|---|
| Technology | Copper Indium Diselenide |
|---|
| 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 | 04/23/2008 |
|---|
| Technology | Cadmium Telluride |
|---|
| Title | FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING |
|---|
| Link | (PDF 466 KB) Download Acrobat Reader. |
|---|
| Authors | A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando |
|---|
| Description | We have observed that routine maintenance procedures such as CdTe target replacement and cleaning of the corresponding ground shield influence the deposition rate and the quality of the film. For example it has been found that the pinhole density reaches its maximum right after the cleaning of the ground shield and remains relatively high for a few subsequent depositions. On the other hand once a coating of CdTe is developed on the ground shield the pinhole density becomes vanishingly small although the deposition rate can slow by as much as 50% as the ground shroud coating builds up.
Not only does this present difficulties for maintaining a solid efficiency baseline throughout the sputtering target life cycle, it also reflects changes in the sputtering plasma. Being a plasma-assisted deposition technique, magnetron sputtering offers a wide range of tweaking opportunities to create thin films with desired physical properties. Without good understanding of the plasma processes the sputtering process can become excessively complicated.
The basic principles of magnetron sputtering are well known and readily available in the literature. It is important to apply those principles to a specific deposition process and equipment. In this report we provide the results of the potential distribution measurements done in one of the CdTe deposition chambers at the University of Toledo. This is the same chamber we recently reported the study of the deposition rate and the CdTe film morphology. These measurements of the plasma allow us to link the typical process control data from pressure gauges and power meters to the properties of the deposited film to potential distributions inside the chamber and plasma parameters extracted from the Langmuir probe measurements. |
|---|
| Venue | University of Toledo (CdTe), subcontract ZXL-5-44205-01, quarterly report |
|---|
| Source | University of Toledo |
|---|
| Document Type | Quarterly Report (Adobe Postscript file) |
|---|
| Resource Date | 03/2008 |
|---|
|
| Post Date | 04/23/2008 |
|---|
| Technology | Cadmium Telluride |
|---|
| Title | FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING |
|---|
| Link | (PDF 744 KB) Download Acrobat Reader. |
|---|
| Authors | A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando |
|---|
| Description | We have developed a theory of ac response by systems of distributed diodes in parallel with resistors and capacitors connected through resistive electrodes that can represent many practical devices including photovoltaics and Schottky junctions. In particular, we have shown that:
1. There exist three lateral decay lengths related to the system diodes, shunt resistors, and capacitances respectively that determine the effective frequency-dependent lateral decay length L and describe the physics of ac response in such distributed systems;
2. The response is frequency-independent below a certain characteristic frequency, above which it strongly depends on testing frequency;
3. The 1D and 2D systems behave similarly in the large device regime, l >> L, where l is the device lateral dimension, while in the small device regime, l << L, 2D systems exhibit certain unique behavior;
4. Both the capacitance and conductance are described by closed form analytical expressions as functions of frequency and dc bias and are parametrically dependent on system material characteristics;
5. Our theoretical results establish a basis for a type of admittance characterization applicable to a wide variety of semiconductor structures including photovoltaics and Schottky junctions. |
|---|
| Venue | University of Toledo (CdTe), subcontract ZXL-5-44205-01, quarterly report |
|---|
| Source | University of Toledo |
|---|
| Document Type | Quarterly Report (Adobe Postscript file) |
|---|
| Resource Date | 03/2008 |
|---|
|
|
|
