Fabrication of Cu2ZnSn(S,Se)4 solar cells via an ethanol-based sol-gel route using SnS2 as Sn source

Cu2ZnSn(S,Se)4 semiconductor is a promising absorber layer material in thin film solar cells due to its own virtues. In this work, high quality Cu2ZnSn(S,Se)4 thin films have been successfully fabricated by an ethanol-based sol-gel approach. Different from those conventional sol-gel approaches, SnS2 was used as the tin source to replace the most commonly used SnCl2 in order to avoid the possible chlorine contamination. In addition, sodium was found to improve the short-circuit current and fill factor rather than the open-circuit voltage due to the decrease of the thickness of small-grained layer. The selenized Cu2ZnSn(S,Se)4 thin films showed large densely packed grains and smooth surface morphology, and a power conversion efficiency of 6.52% has been realized for Cu2ZnSn(S,Se)4 thin film solar cell without antireflective coating.