Optimization of CZTSe Thin Films Using Sequential Annealing in Selenium and Tin-Selenium Environments.

CuZnSnSe (CZTSe) is a promising material for thin-film solar cells due to its suitable band gap, high absorption coefficient, and composition of earth-abundant and nontoxic elements. In this study, we prepared CZTSe thin films from Cu/SnSe and ZnSe stacks using a two-step annealing process. Initially, Cu-Sn-Se (CTSe) films were synthesized by sequential deposition and annealing of Cu and SnSe precursors in either a selenium (Se) or tin-selenium (Sn+Se) atmosphere.