Formation of Cu2ZnSnS4 thin films and optimization of the optical bandgap using the Taguchi approach

Abstract

Cu2ZnSnS4 thin films were synthesized by deposition of Cu–Zn–Sn alloy films on soda-lime glass using flash evaporation PVD of pre-alloyed powders followed by sulfurization anneal. The influence of process parameters on the structure, morphology and optical response of as-deposited and annealed films was investigated by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy, and UV–visible spectroscopy. Since the preparation process, which influences the structure and chemical composition of the films, determines the optical bandgap of CZTS absorber layers, the Taguchi method was utilized to better predict the effect of process variables to achieve the optimal bandgap. According to the outcomes, the significant parameters, in sequence, were sulfurization time, the composition of PVD source powder, sulfurization temperature, and sulfur content. The prepared sample according to the optimal condition suggested by the Taguchi method showed an optical bandgap of 1.56 eV.