LIGHTWEIGHT TANDEM GAAS CUINSE2 SOLAR-CELLS

High-efficiency, ultralightweight, mechanically stacked 4-cm2 thin-film tandem solar cells have been successfully fabricated. The tandem stack consists of a single-crystal, thin-film Ga(Al)As cell fabricated by the cleavage of lateral epitaxy for transfer (CLEFT) process adhesively bonded to the top of a CdZnS CuInSe2 polycrystalline thin-film cell deposited on glass. Maximum tandem efficiency in four-terminal configuration of 21.6-percent AMO has been demonstrated. This represents the highest thin-film cell efficiency reported to date. Individual subcells with efficiencies of 19.5 percent for CLEFT GaAs, and 3.0 percent for CuInSe2 have also been achieved. Cell specific power as high as 600 W/kg has been achieved with a 4-cm2 cell weight of 188 mg without coverglass, at an efficiency of 20.8-percent AMO. © 1990 IEEE