Influence of annealing on microstructural and photoelectrochemical characteristics of CuSCN thin films via electrochemical process

Thin films of p-type β-CuSCN were deposited on indium-tin oxide glass substrates via electrochemical process. Various annealing temperatures (200, 300 and 400 °C) were taken into consideration. The influence of annealing temperature on structural, optical, electrical and photoelectrochemical characteristics of β-CuSCN thin films were investigated. Results from X-ray diffraction indicated as-obtained β-CuSCN thin film was in a hexagonal close pack crystal structure. We found that the crystallographic orientation changed and the optical energy band gap slightly increased with increasing annealing temperatures. These properties made CuSCN films annealed at 400 °C a better photoelectrochemical performance with photocurrent density of about -0.39 mA/cm² at -0.5 V vs. SCE. This value is about 5 times higher than the as-deposited CuSCN film. Observed higher photocurrent density is likely due to the intrinsic of a higher charge carrier concentration, and a lower resistance within CuSCN crystal and at CuSCN/electrolyte interface.