Device physics of thin-film polycrystalline cells and modules. Annual subcontract report, 6 December 1995--5 December 1996
- Colorado State Univ., Fort Collins, CO (United States). Dept. of Physics
During 1996, a number of projects were carried out at Colorado State University (CSU) on Cu(In, Ga)Se{sub 2} (CIGS) and CdTe solar cells and small modules. CSU participated directly in the deposition of CIGS at NREL for the first time. Five separate substrates were used, and sodium was both deliberately introduced and deliberately blocked from exiting soda-lime substrates. In general, sodium in the CIGS led to better junction properties and higher efficiency. In other CIGS measurements, CSU showed that electrodeposited absorber material made at NREL produced competitive cells. Voltages, normalized to bandgap, were about 50 mV less than the best evaporated CIGS cells. CSU also showed, in collaboration with Solarex, that the existence of a high-resistivity ZnO layer is probably not critical for cells with relatively thick CdS window layers. In collaboration with seven CdTe fabrication laboratories, CSU measured the effect of CdS thickness on cell parameters. Although voltage and fill-factor generally degrade for CdS thickness below 100 nm, the exceptions suggest that with at least some fabrication techniques, CdS thickness can be reduced to the point that high quantum efficiency in the blue and a good diode junction are not mutually exclusive. A number of artifacts were investigated that appear in module measurement and analysis, but that are generally negligible for small test cells. These include effects due to module-cell geometry and misleading conclusions from selective illumination experiments. NREL data from the highest-efficiency CIGS and CdTe cells were analyzed to provide direct comparisons of different fabrication techniques. The three commonly used NREL deposition systems have produced CIGS cells with very similar junction properties. 20 figs.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado State Univ., Fort Collins, CO (United States). Dept. of Physics
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC36-83CH10093
- OSTI ID:
- 541851
- Report Number(s):
- NREL/SR-520-23589; ON: DE98000765; TRN: AHC29723%%70
- Resource Relation:
- Other Information: PBD: Oct 1997
- Country of Publication:
- United States
- Language:
- English
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