40.8% efficient inverted triple-junction solar cell with two independently metamorphic junctions

Abstract

A photovoltaic conversion efficiency of 40.8% at 326 suns concentration is demonstrated in a monolithically grown, triple-junction III-V solar cell structure in which each active junction is composed of an alloy with a different lattice constant chosen to maximize the theoretical efficiency. The semiconductor structure was grown by organometallic vapor phase epitaxy in an inverted configuration with a 1.83 eV Ga.51 In.49 P top junction lattice-matched to the GaAs substrate, a metamorphic 1.34 eV In. 04 Ga.96 As middle junction, and a metamorphic 0.89 eV In.37 Ga.63 As bottom junction. The two metamorphic junctions contained approximately 1× 105 cm-2 and 2-3× 106 cm-2 threading dislocations, respectively. © 2008 American Institute of Physics.