Benign solution processed Cu2ZnSn(Se, S)4 photovoltaic

Solution-based approach to process earth-abundant Cu2ZnSn(Se, S)
₄
is proved to be a promising route for thin-film photovoltaic fabrication. Combining fully dissolved zinc/tin (Zn/Sn) and copper (Cu) hydrazinuim constituents in the ethanolamine (EA) and its mixture with dimethylsulfoxide (DMSO) forms the CZTS precursor, which facilitates the composition adjustment. All solutes in this precursor solution are in molecular scale intermixed with excellent homogeneity. Innovated 2-step annealing using sulfur and selenium vapor sequentially assists continuous grain growth, and prevents Mo(S, Se)
₂
formation. Resulting device achieves 7.5% power conversion efficiency.