H2O2Treatment of Electrochemically Deposited Cu2O Thin Films for Enhancing Optical Absorption

Abstract

Cu2O is considered to be promising as an absorber layer material of solar cells, but its band gap (about 2.1 eV) is larger than the optimum one (about 1.5 eV). CuO has a smaller band gap of about 1.35 eV. Therefore, we attempted to oxidize Cu2O using H2O2to increase oxygen ratio and decrease band gap. Cu2O thin films were deposited on indium-tin-oxide-coated glass from an aqueous solution containing CuSO4, lactic acid, and KOH by the galvanostatic electrochemical deposition at 40°C with current density of −1 mA/cm2. Then, the as-prepared copper oxide thin film was dipped in H2O2(30%) at fixed temperature to oxidize for some time. By the H2O2treatment at room temperature, the oxygen content was increased, and the band gap was decreased.