Over 31%-efficient GaAs/GaSb tandem concentrator solar cells

GaAs/GaSb tandem concentrator solar cells were fabricated. Both, the GaAs concentrator top cells and the GaSb bottom cells were produced using an inexpensive technology: LPE etchback-regrowth process and Zn vapor-phase diffusion process, respectively. The antireflection coatings and contact alloys were improved. A tandem efficiency of 31.1% under 100/spl times/AM1.5d was achieved. The first tandem concentrator module with an area of 486 cm/sup 2/ achieved an outdoor efficiency of 23.0%.