Degradation Mechanism of III-V Triple Junction Solar Cells Analyzed Using Step Stress Tests

We analyzed the degradation mechanism of GaInP/GaInAs/Ge triple junction solar cells without coating any protective film. Gradual degradation in the dark and light I-V characteristics of the solar cells were observed after the step stress accelerated degradation tests (SSADT) were conducted on these devices sequentially at 90, 110, 130 and 150°Cfor 25, 55, 85 and 135 hours, respectively. The recombination current in the depletion region at the chip perimeter of solar cells, resulting in the decrease of open-circuit voltage (VOC), fill factor (FF) and efficiency, is suggested to be the important degradation mechanism for GaInP/GaInAs/Ge triple junction solar cells.