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Search the Thin-film Resource Database for more articles, news, and reports.

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	05/11/2009
Technologies	Cadmium Telluride, Copper Indium Diselenide
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	05/11/2009
Technology	Cadmium Telluride
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 3.6 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	The three overall emphases of this subcontract were the following: 1) improving our understanding of key aspects of CdS/CdTe solar cell device physics, 2) improving our understanding of magnetron sputtering and increasing the sputter deposition rate while maintaining high device quality, and 3) reducing the thickness of CdTe layers in the CdS/CdTe cell below 0.5 ?m while maintaining voltage and fill factor.
Venue	University of Toledo, subcontract ZXL-5-44205-01, Final Report
Source	University of Toledo
Document Type	Final Report (Adobe Postscript file)
Resource Date	04/2009

Post Date	05/11/2009
Technology	General Interest
Title	BEST PRODUCTION-LINE PV MODULE EFFICIENCY VALUES: FROM MANUFACTURERS? WEBSITES
Link	(MS Word 56 KB)
Author	B. Von Roedern
Description	Table of commercial module efficioencies, per module manufacturers websites.
Venue	NREL NCPV
Source	National Renewable Energy Laboratory
Document Type	Other Items (Word document)
Resource Date	03/2009

Post Date	04/27/2009
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 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	04/22/2009
Technology	Copper Indium Diselenide
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	03/13/2009
Technologies	Amorphous and Thin Film Silicon, Copper Indium Diselenide
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
Link	(PDF 282 KB) Download Acrobat Reader.
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	03/11/2009
Technology	Cadmium Telluride
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 471 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	RTSE has been applied to investigate the dielectric functions of CdTe and CdS thin films sputtered at different temperatures. These dielectric functions are modeled using the critical point (CP) parabolic band approximation. Key characteristics can be deduced including grain size, excitation group speeds, stress, and temperature from the CP parameters. Capabilities for on-line optical monitoring are sought to provide information, not only on layer thicknesses and compositions, but also on grain size, stress, and temperature. As a first application, the parameterization was used to analyze the ellipsometric spectra of a stepwise etched CdTe solar cell. In this study, depth profiles in the void and grain size near the CdTe/CdS interface have been obtained.
Venue	university of Toledo, subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/19/2008

Post Date	02/24/2009
Technologies	Cadmium Telluride, Copper Indium Diselenide
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	11/21/2008
Technologies	Cadmium Telluride, Copper Indium Diselenide
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 107 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 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	11/19/2008
Technology	Cadmium Telluride
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 1.1 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	This report presents: 1) properties of phosphorus-doped CdTe films prepared by sputtering from pressed targets of CdTe and Cd3P2, 2) optimization studies on ultra-thin CdS/CdTe cells with efficiencies exceeding 10% for 0.5?
Venue	University of Toledo, subcontract ZXL-5-44205-01, (CdTe), quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2008

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