Lightweight, Flexible, High-Efficiency III-V Multijunction Cells

Large-area (26.6 cm²), thin GaInP/GaInAs/Ge triple-junction (TJ) solar cells with thickness as low as 50 mum were demonstrated. The average conversion efficiency of fifty thin TJ cells is 28 %, 1-sun AMO. The thin TJ cells showed nominal performance after welding of interconnects and flexibility test (50 mm curvature radius). Prototype coupons made with these thin TJ cells met flexible solar module bending requirement of 100 mm radius. The thin-cell coupons showed a specific power of 500 W/kg and a power density of 325 W/m² . Ultra-thin (<10 mum thick) GaInP/Ga(In)As dual-junction (DJ) cells with size ranges from 0.5 to 26.6 cm² were fabricated using 4" Ge or GaAs wafers. Preliminary test data of the ultra-thin DJ cells showed a specific power of 2067 W/kg and a power density of 283 W/m². The ultra-thin solar cells continued to demonstrate nominal performance after handling and flexing to a radius of 12 mm. Our results suggested that both the thin cell and the ultra-thin cell technologies can be incorporated with current and future solar cell designs