Effect of selenization on sprayed Cu2ZnSnSe4 thin film solar cell

Abstract We made Cu2ZnSnSe4 (CZTSe) thin film solar cell using spray pyrolysis. The photo-absorber CZTSe was fabricated by post-selenization of sprayed Cu2ZnSnS4 (CZTS) film, and In2S3, which was adapted as a buffer layer, was also deposited by spray pyrolysis. The sprayed CZTS films were annealed at 530 °C for 15 min and 25 min in Se vapor ambient, and through the selenization CZTS films were converted to CZTSe films. These re-crystallized CZTSe films were used as the photo-absorber of solar cell. Conversion efficiency of 2.39% was obtained with 25 min annealed CZTSe, whereas 0.27% conversion efficiency was obtained with 15 min annealed one. By comparing characterization results for both solar cells, it might be concluded that the conversion efficiency was dominated by the selenization condition of the photo-absorber layer which affected crystal quality of the photo-absorber.