Selenization post-treatment Ag-alloyed Cu2ZnSn(S,Se)4 films for enhancing photovoltaic performance of solar cells.

The Ag-alloyed Cu 1.9 Ag 0.1 ZnSn(S,Se) 4 (CAZTSSe) films were prepared by selenidation of Cu 1.9 Ag 0.1 ZnSnS 4 (CAZTS) precursor films under various selenidation conditions. The effects of selenidation time and selenidation temperature on the composition, morphology, optical band gap (Eg) and device performance of CAZTSSe films were systematically studied. It is found that the selenidation temperature of 480 °C and selenidation time of 10 min provide a favorable selenidation environment for the growth of the film, which can promote grain growth and form a thick and smooth film. This has been strongly confirmed through relevant tests. In addition, the analysis of performance characterization of the films shows that the Eg of the films can be adjusted via adjusting the selenidation conditions, so as to improve the electrical properties. Finally, the CAZTSSe solar cell with a photoelectric conversion efficiency (PCE) of 5.94 % and an open circuit voltage (V oc) of 397 mV was successfully prepared at the selenidation temperature of 480 °C and selenidation time of 10 min. • A new method to improve V oc and PCE of CZTSSe solar cell by Ag doping is put forward. • This is the first report on the effect of post-selenization on CAZTSSe solar cell. • Eg of CAZTSSe can be continuously adjusted by adjusting the selenidation condition. • The effect of selenization condition on PCE is ascribed to change of V OC and FF. • This study shows hopeful character of selenidation condition in increasing the PCE. [ABSTRACT FROM AUTHOR]