Development of p-on-n GaInP2/GaAs tandem cells

We report on the development of p-on-n GaInP₂/GaAs two-terminal, monolithic cascade cells. The devices are of interest for space applications because they have higher efficiencies and power-to-weight ratios than existing single junction devices currently in use, they can be readily used in current satellite array designs, and they are compatible with current manufacturing capabilities at facilities such as the Applied Solar Energy Corporation. The p-on-n cascade cells have been grown at RTI by atmospheric pressure organometallic vapor phase epitaxy at 650°C on n-type GaAs. The best device to date, with active area of 0.141 cm², has an active area efficiency of 20.1 percent under AM0 illumination, before an antireflection coating (ARC). Taking into account the ARC and a grid with a 5 percent obscuration, the device projects to a total area efficiency of 25.2 percent, nearly equal to that achieved for n-on-p cells. Devices of area 4 cm² have also been grown. The large-area devices have attained efficiencies of 21.8 percent under AM0 illumination, with ARC