In this letter we report a combination of surface chemical and voltammetric treatments that optimize the stability and performance ofp‐Si/V2+−V3+, 4MHCl/C solar cells. The power conversion efficiency is 6.1% under 60‐mW/cm2illumination. The results of capacitance‐voltage measurements and the improved solar cell properties are discussed on the basis of an electrolyte‐oxide‐semiconductor energy band diagram.