Effect of Three Different Complexing Agents on the Deposition of ZnS Buffer Layer in Copper Indium Gallium Selenide Solar Cell

Cadmium sulfide (CdS) buffer layer has been replaced with zinc sulfide (ZnS) thin film owing to toxicity. ZnS thin films were fabricated by using chemical bath deposition (CBD). The characteristics of ZnS thin films are closely related to the use of complexing agents to control the concentration of Zn²⁺ ions during the deposition process. The optimal conditions for the fabrication of ZnS thin film were determined by adjusting the concentrations of ethylenediamine tetra acetate acid, hexamethylene tetramine, and sodium citrate. The morphology of the fabricated ZnS thin film was examined using field-emission scanning electron microscopy. The measurement was carried out using ultraviolet-visible spectroscopy and the light penetration was measured at 300∼800 nm using a tungsten lamp. The best ZnS thin film with a dense surface was prepared using sodium citrate complexing agent.