Room Temperature Pulse Electrodeposition of CdS Thin Films for Application in Solar Cells and Photoelectrochemical Cells

Polycrystalline CdS thin films comprising of hexagonal crystal structure are successfully fabricated by pulse electrodeposition using a two-electrode system at room temperature. The method utilizes tartaric acid as a complexing agent for the first time that minimizes the formation of colloidal sulfur while optimizing the deposition potential and avoids conventional post-deposition heat-treatment step. Additionally, deposition time is varied to obtain the desired thickness of CdS films suitable for application in thin films solar cells. Pulse electrodeposited CdS films are comprehensively characterized using SEM, XRD and micro-Raman analyses unveiling the stoichiometric polycrystalline hexagonal CdS films. The bandgap is determined to be around 2.4 eV from optical studies. Flat-band potential and carrier density are inferred to be -0.82 V vs SCE and 8.51 x 10(18) cm(-3) respectively, from the Mott-Schottky analysis. Photoelectrochemical studies show a photocurrent density of about 0.2 mA/cm(2) at 0.2 V vs SCE for the optimized films, which is competent with previously reported values. These pulse electrodeposited CdS films prepared without any high-temperature treatment are of high quality with desirable properties and are suitable for application in thin films solar cells and photoelectrochemical cells. (C) 2018 The Electrochemical Society.