Direct current sputter deposited CuO layers on conductive glass: Towards a maximum photoelectrochemical response of photocathodes

Abstract

This study investigates the photoelectrochemical properties of copper-oxides and their use as photoelectrodes deposited onto conductive glass (fluorine-doped tin oxide) via reactive direct current magnetron sputtering. Through careful optimization of sputtering parameters, we hint that among various phases formed (Cu₂O, Cu₄O₃ and CuO), an optimized cupric oxide layer can be grown that sputtered under an oxygen flow rate of 7 sccm exhibits the highest photoelectochemical activity that can reach a maximal incident photon-to-current efficiency of 12.3 %. A key factor in this optimization is the precise control of oxygen partial pressure, which facilitates the crystallization of Cu_xO_y, leading to enhanced photoelectrochemical performance. Further improvements in efficiency were investigated by varying annealing temperatures and film thicknesses. This work demonstrates a simple yet effective method for fabricating high-efficiency CuO photocathodes.