Selenization of mixed metal oxides for dense and ZnSe-free Cu_2ZnSnSe_4 absorber films

摘要

Cu_2ZnSnSe_4 (CZTSe) films were prepared by direct selenization of Cu_2O, SnO_2 and Zn_2SnO_4 precursors. Oxides precursors were prepared by baking hydroxides precipitation. In order to obtain ZnSe-free CZTSe films, Zn_2SnO_4 was used to replace separated ZnO and SnO_2 as one of the precursors. Through X-ray diffraction (XRD), scanning electron microscopy (SEM), it was found that CZTSe films, with micron-sized dense grains, were obtained in our work. From Raman spectra, it was also found that the ZnSe secondary phase was absent after the selenization. An energy bandgap about 0.86 eV was obtained in our work, which confirmed the Stannite-CZTSe structure.