Photoelectrochemical response for Cu-doped ZnIn₂S₄ electrode created using chemical bath deposition

Polycrystalline Cu-doped ZnIn₂S₄ samples were grown on fluorine doped-tin-oxide-coated glass substrates using chemical bath deposition. The effect of [Cu]/[Cu+Zn] molar ratio in solution bath on the structural, optical and photoelectrochemical properties of the samples was investigated. From the results of X-ray diffraction (XRD) patterns of samples, a small shift in the peaks to a higher-angle was observed with the increase in Cu content in the film. The thicknesses and direct band gaps of the samples are in the ranges of 520-1260 nm and 2.51-2.09 eV, as obtained from surface profile measurement and transmittance/reflectance spectra, respectively. The highest photoelectrochemical response of samples was 1.15 mA/cm² at an external potential of + 1.0 V vs. an Ag/AgCl electrode in 0.5 M K ₂SO₄ solution under illumination using a 300W Xe lamp system with the light intensity set at 100 mW/cm².