Very high efficiency InGaP/GaAs dual-junction solar cell manufacturing at Emcore Photovoltaics

The electrical performance and space qualification data of very high efficiency dual junction n/p InGaP/GaAs (on Ge) solar cells manufactured at Emcore Photovoltaics are described. The minimum average beginning-of-life (BOL) conversion efficiency of large area (27.5 cm/sup 2/) solar cells currently in production is 23.0% (28/spl deg/C, 1 sum AM0, 135.3 mW/cm/sup 2/). The resulting power output per cell is 0.86 watts. The highest efficiency obtained of 25.3% represents a record for a large area dual junction cell. The results presented here are for solar cells that have an optimized end-of-life (EOL) structure. The power remaining factors after irradiation with 1-MeV electrons at fluences of 5E14, 1E15, and 3E15 e/cm/sup 2/ are 0.89, 0.84, and 0.74 respectively. The results of full space qualification testing including electrical, radiation exposure, temperature coefficients, thermal cycling, humidity, optical, and mechanical measurements are presented.