Over 35-percent efficient GaAs/GaSb tandem solar cells

The efficiency of GaAs solar cells can be substantially increased by locating an infrared-sensitive booster solar cell behind a transparent GaAs cell. Infrared-sensitive GaSb cells and visible-light-sensitive GaAS cells designed for use with concentrated sunlight are described. Prismatic cover slides are used to effectively eliminate grid shading losses for both the GaAs and the GaSb cells. With prismatic cover slides, the best component cell efficiencies add up to 38.2% under concentrated sunlight (100*AM1.5D). Two-terminal tandem cell circuit cards containing nine transparent GaAS cells and nine GaSb cells are also described. Without cell prismatic covers, circuit-level energy conversion efficiencies near 30% (AM1.5D) are demonstrated.>