Improved performance of cadmium chalcogenide photoelectrochemical cells: surface modification using copper sulphide

Abstract

The effect of copper sulphide species on the photoactivity of cadmium chalcogenide photoelectrodes is discussed. This species, believed to be CuS, is applied using two methods. In the first, polished CdSe electrodes are dipped into a solution containing cupric ions, immersed in polysulphide solution and subsequently operated as anodes. In the latter technique, copper species migrates from a sulphided, brass counter electrode to an etched CdSe or CdSe_xTe_1-x photoelectrode. In the former case, the main effect of the copper treatment is an increase in the short-circuit photocurrent while in the latter case, the dark cathodic current decreases and the open-circuit voltage increases. The effect of these treatments is explained by preferential deposition of copper (or some copper-containing species) at surface defect sites, resulting in the partial passivation or blocking of these sites.