Electrosynthesis of CZTS films by sulfurization of CZT precursor: Effect of soft annealing treatment

•Eco friendlier, low cost chemical method has been adopted for synthesis of CZTS thin films.•First report on the effect of soft annealing temperature on properties of CZTS thin films.•Pure CZTS phase is obtained for soft annealed film followed by sulfurization. In the present work, CZTS thin films have been prepared by sulfurization of electrodeposited Cu–Zn–Sn (CZT) precursor. Prior to sulfurization, as-deposited CZT precursors have been soft annealed in Ar atmosphere at different temperatures (250–350°C). The structural, morphological, compositional and optical properties of the films have been investigated in detail. It is found that, soft annealing temperature has a significant impact on the properties of CZTS thin films. The systematic study on the improvement in the properties of CZTS films using soft annealing route has been studied and discussed.