High-efficiency cadmium and zinc-telluride-based thin-film solar cells. Annual subcontract report, 1 March 1990--28 February 1991
- Georgia Inst. of Tech., Atlanta, GA (United States)
This report describes research into polycrystalline CdTe solar cells grown by metal-organic chemical vapor deposition. Efficiencies of {approximately}10% were achieved using both p-i-n and p-n structures. A pre-heat treatment of CdS/SnO{sub 2}/glass substrates at 450{degrees}C in hydrogen atmosphere prior to the CdTe growth was found to be essential for high performance because this heat treatment reduces oxygen-related defects from the CdS surface. However, this treatment also resulted in a Cd-deficient CdS surface, which may in part limit the CdTe cell efficiency to 10% due to Cd vacancy-related interface defects. Preliminary model calculations suggest that removing these states can increase the cell efficiency from 10% to 13.5%. Photon absorption in the CdS film also limits the cell performance, and eliminating this loss mechanism can result in CdTe efficiencies in excess of 18%. Polycrystalline, 1.7-e, CdZnTe films were also grown for tandem-cell applications. CdZnTe/CdS cells processed using the standard CdTe cell fabrication procedure resulted in 4.4% efficiency, high series resistance, and a band-gap shift to 1.55 eV. The formation of Zn-O at and near the CdZnTe surface is the source of high contact resistance. A saturated dichromate each prior to contact deposition was found to solve the contact resistance problem. The CdCl{sub 2} treatment was identified as the cause of the observed band-gap shift due to the preferred formation of ZnCl{sub 2}. 59 refs.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Georgia Inst. of Tech., Atlanta, GA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-83CH10093
- OSTI ID:
- 10121767
- Report Number(s):
- NREL/TP-214-4580; ON: DE92001198
- Resource Relation:
- Other Information: PBD: Feb 1992
- Country of Publication:
- United States
- Language:
- English
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High Efficiency Cadmium and Zinc Telluride-Based Thin Film Solar Cells, Final Subcontract Report, 1 March 1989 - 28 February 1990
High efficiency cadmium telluride and zinc telluride based thin-film solar cells. Annual subcontract report, 1 March 1990--28 February 1992
Related Subjects
36 MATERIALS SCIENCE
CADMIUM TELLURIDE SOLAR CELLS
FABRICATION
PROGRESS REPORT
CHEMICAL VAPOR DEPOSITION
HEAT TREATMENTS
CADMIUM SULFIDES
TIN OXIDES
GLASS
SUBSTRATES
EFFICIENCY
CRYSTAL GROWTH
THIN FILMS
MATERIALS TESTING
140501
360601
PHOTOVOLTAIC CONVERSION
PREPARATION AND MANUFACTURE