40% efficient metamorphic GaInP∕GaInAs∕Ge multijunction solar cells

Abstract

An efficiency of 40.7% was measured and independently confirmed for a metamorphic three-junction $\mathrm{GaInP}∕\mathrm{GaInAs}∕\mathrm{Ge}$ cell under the standard spectrum for terrestrial concentrator solar cells at 240 suns ($24.0\mathrm{W}∕{\mathrm{cm}}^2$ , AM1.5D, low aerosol optical depth, $25°\mathrm{C}$ ). This is the initial demonstration of a solar cell with over 40% efficiency, and is the highest solar conversion efficiency yet achieved for any type of photovoltaic device. Lattice-matched concentrator cells have now reached 40.1% efficiency. Electron-hole recombination mechanisms are analyzed in metamorphic ${\mathrm{Ga}}_x{\mathrm{In}}_{1-x}\mathrm{As}$ and ${\mathrm{Ga}}_x{\mathrm{In}}_{1-x}\mathrm{P}$ materials, and fundamental power losses are quantified to identify paths to still higher efficiencies.