Preparation and characterizations of visible light-responsive (Ag-In-Zn)S thin-film electrode by chemical bath deposition

The thin-film form of (Ag-In-Zn)S quaternary semiconductor was prepared from acidic aqueous solutions. A low temperature and low cost chemical deposition method is presented. Grazing incidence X-ray diffraction, UV-visible spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy characterized the crystal phases, optical absorptions, surface morphologies, and compositions of the films. Samples are polycrystalline composed of ZnS/AgInS₂/AgIn₅S₈ crystal phases. The thickness and optical absorption edge, depending on dipping numbers, lie between 0.58 and 1.29 μm and 2 and 3.1 eV, respectively. Photoresponse measurements were recorded by a scanning potentiostat in a standard three-electrode electrochemical setup under a 300 W Xe lamp illumination with the intensity of 100 mW/cm². For the sample dipped in the chemical bath for three times (Sample C), the photocurrent density of 6.275 mA/cm² was obtained in contact with K₂SO₃ and Na₂S aqueous electrolyte with an applied potential of 1 V vs. SCE reference electrode. The corresponding maximum photon-to-current efficiency is 55% at λ = 500 nm.