Chemical bath deposition of zinc sulfide based buffer layers using low toxicity materials

ZnS thin films that are used as buffer layers in thin film solar cells are usually deposited by chemical bath deposition using hydrazine hydrate as a complementary complexing agent. This material is, however, highly hazardous and its replacement by a less-hazardous material is desirable. In this work thin films of zinc sulfide have been deposited using sodium citrate as a novel complementary complexing agent and experiments performed to determine the optimum conditions for producing conformal films, free from pinholes. The layers deposited were found to consist of Zn and S but with a small concentration of O present. Data relating to how the deposition conditions affected the physical properties of the deposited layers are reported.