Non-toxic solution processed Cu2ZnSn(SSe)4 thin films for photovoltaic Applications: A review

Abstract

Due to its earth-abundant and environmentally safe constituents, as well as suitable optical properties like a high absorption coefficient > 104 cm−1 and a direct bandgap of 1.5 eV Kesterite Cu2ZnSnS4 (CZTS) has emerged as a celebrated successor to CuInGaS2 (CIGS) as the absorber layer in thin film solar cells. The binary chalcogenides are first synthesized, and then they are dispersed in hydrazine, yielding the solution process, which has so far the highest conversion efficiency of 12.6% for any CZTSSe fabrication process. In light of hydrazine’s explosive, heptotoxic and carcinogenic properties, further study has been done on the simple synthesis of CZTS films from non-toxic solutions. Numerous non-hydrazine solutions, which are significantly safer to use, have been researched. The formation of single kesterite phase with better control over secondary phases has been the key to its success in photovoltaic applications. In all solution-based approaches for semiconductor thin films, the film growth proceeds from the release of cations and anions from the precursor salts, and their subsequent reactions.