An improved efficiency thin film solar cell is disclosed. Nanoscale indentations or protrusions are formed on the cross sectional surface of a carrier layer, onto which a thin metal film is deposited. Additional layers, including semiconductor absorber and collector layers and a window layer, are disposed on the metal film, thereby completing the solar cell. The nanostructure underlying the metal film serves to reduce the work function of the metal and thereby assists in the absorption of holes created by solar photons. This leads to more efficient electricity generation in the solar cell. In a further embodiment of the present invention the cross sectional surface of the semiconductor absorber layer is also modified by nanoscale indentations or protrusions. These indentations or protrusions have the effect of altering the size of the semiconductor band gap, thereby optimizing the radiation absorption properties of the solar cell.