Highly conductive semitransparent graphene sheets are combined with an n-type silicon (n-Si) wafer to fabricate solar cells with power conversion efficiencies up to 1.5% at AM 1.5 and an illumination intensity of 100 mW cm(-2). The Schottky junction solar cells can be extended to other semiconducting materials in which graphene serves multiple functions as active junction layer, charge transport path, and transparent electrode.