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U.S. Department of Energy
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Stable, high-efficiency, CuInSe/sub 2/-based, polycrystalline, thin-film tandem solar cells: Final subcontract report, 16 March 1984-15 March 1987

Technical Report ·
DOI:https://doi.org/10.2172/5565191· OSTI ID:5565191

The long-term objective of this research was to obtain a stable, thin-film solar cell based on polycrystalline materials with an efficiency of 15%. The approach was to make a tandem cell based on CuInSe/sub 2//CdS as the bottom cell and CdTe/CdS as the top cell. An essential feature was to develop a CdTe cell with transport contacts. A suitable contacting system was developed using transparent conducting oxides (ITO and SnO/sub 2/) in conjunction with a thin layer of copper. Cells were made with efficiencies over 8.5%. A reproducible fabrication process for CuInSe/sub 2//(CdZn)S cells was developed based on CuInSe/sub 2/ films grown by vacuum evaporation using Knudsen-type effusion sources. These cells were made with efficiencies over 10%. The composition of the CuInSe/sub 2/ films can be varied over a considerable range and still yield high-efficiency cells. Adding Zn to the CdS did not increase the V/sub oc/ of the devices; analysis showed that the V/sub oc/ is not controlled by interface recombination. The effect of oxidizing and reducing heat treatments on CuInSe/sub 2/ cells is to change carrier concentration and thus V/sub oc/. Analysis suggests that J/sub o/ is controlled by band-to-band recombination. Monolithic tandem CuInSe/sub 2/ CdTe cells have been made with efficiencies of approx.3%, demonstrating the feasibility of this approach. 33 refs., 36 figs., 37 tabs.

Research Organization:
Delaware Univ., Newark (USA). Inst. of Energy Conversion
DOE Contract Number:
AC02-83CH10093
OSTI ID:
5565191
Report Number(s):
SERI/STR-211-3249; ON: DE88001116
Country of Publication:
United States
Language:
English