11.5% solar conversion efficiency in the photocathodically protected p-InP/V3+-V2+-HCI/C semiconductor liquid junction cell

Oxidation of the surface of p-InP with alkaline peroxide and treatment with dilute potassium cyanide increase the efficiency of the p-InP/V2+−V3+ -HCl/C cell to 11.5%. The open circuit voltage of the cell follows the redox potential of the solution over a 0.5 V range. The lack of voltage pinning is consistent with photoemission studies of Spicer et al., showing that adsorption of oxygen on p-InP raises the surface fermi level from a position near the valence band maximum to noe near the conduction band minimum.