Cu2ZnSnS4 solar cell prepared entirely by non-vacuum processes

► We studied the Cu2ZnSnS4 (CZTS) solar cell with entire non-vacuum process. ► Single phase CZTS precursor powder obtained by dry ball milling ► Annealing affects screen printed CZTS absorber layer notably by introducing defects. ► In2S3 buffer layer thickness has great effects on the solar cell conversion efficiency. ► Simple, low-cost, low-toxic and high-speed entire non-vacuum fabrication process