Photoelectrochemical solar cells (PSCs), consisting of a photoelectrode, a redox elec-trolyte, and a counter electrode, have been studied extensively. Several semiconductormaterials, including single-crystal and polycrystal forms of n- and p-Si, n- and p-GaAs,n- and p-InP, and n-CdS, have been used as photoelectrodes. These materials, when usedwith a suitable redox electrolyte, can produce solar light-to-current conversion efficiencyof approximately 10%. However, under irradiation, photocorrosion of the electrode in theelectrolyte solution frequently occurs, resulting in poor stability of the cell, so efforts havebeen made worldwide to develop more stable PSCs.