Design of a 13% efficient n-GaAs₁₋ₓPₓ semiconductor–liquid junction solar cell

We report here the design of the most efficient non-aqueous semiconductor–liquid junction solar cell studied to date. Our approach involves the use of ternary semiconductor electrodes made from solid solutions of a large hand gap material, GaP, and a small band gap material, GaAs. We demonstrate here that photoanodes consisting of such materials are capable of simultaneously yielding high open circuit voltages and favourable wavelength response to the solar spectrum. A few n-type semiconductor–liquid junction solar cells in aqueous solutions have been reported to yield high (>10%) solar-to-electrical conversion efficiencies. However, for most materials, rapid photoanodic corrosion dominates the interfacial photochemistry4–8. Non-aqueous solvent systems can suppress electrode decay due to corrosion; but modest (<6%) conversion efficiencies have been observed for all photoanodes studied in solar irradiation conditions. The photoanodes used here yield over 13% solar-to-electrical conversion efficiencies, or more than double the efficiency of any other non-aqueous semiconductor–liquid junction solar cell previously reported.