Enhanced photoelectrochemical properties of CuGa3Se5 thin films for water splitting by the hydrogen mediated co-evaporation method

The influence of film deposition conditions during vacuum co-evaporation, including the flux ratio and the partial pressure of hydrogen, on the structural and photoelectrochemical properties of copper gallium selenide (CGSe) films was examined. The flux ratio between Se and the other metals strongly affected both surface morphology and crystallite size. After ZnS modification, CGSe films grown at flux ratios (J(Se)/J(Cu+Ga)) of 3 to 5 had the highest energy conversion efficiency under AM 1.5G irradiation. In addition, introducing hydrogen during the growth of CGSe films induced the selective growth of the (112) plane and an increase in the grain size. ZnS-modified photocathodes using CGSe with an increased grain size due to hydrogen introduction had high solar energy conversion efficiencies because of their improved structural properties.