Influence of Zinc Content in Ternary ZnCdS Films Deposited by Chemical Bath Deposition for Photovoltaic Applications

Cadmium Zinc Sulfide thin films with different Zn concentration were synthesized in aqueous solution by chemical bath deposition (CBD) method using CdSO4, ZnSO4, CH4N2S for Cd+2, Zn+2, and S−2 ions source, respectively. The as-deposited films are well homogeneous, adherent and free from pinholes. The incorporation of Zn in CdS was found to be dependent on the annealing temperature. Structure, morphology, elemental analysis, optical and photoelectrochemical (PEC) properties of ZnCdS were characterized using X-ray diffraction, atomic force microscopy, energy dispersive spectroscopy, transmission electron microscopy and UV-Vis absorption measurements, respectively. According to EDS analysis the films are non-stoichiometric due to a deficit of sulfur, which becomes more important as the Zn content increases. The absorption edge shifts toward the lower wavelength region and hence the bandgap of the films increases as the Zn content increases. The values of optical absorption edge are found to change from 2.42 eV for CdS and 2.90 eV for ZnS thin films. The PEC and linear sweep voltammetry performance of the Zn doped CdS films were examined by chronoamperometry technique which provided a significant high potential current due to increase of the electrical conductivity as compared to CdS film.