Performance enhancement of Cu2ZnSn(S,Se)4 solar cell by inserting Sb and Sb2Se3 doping layer at the bottom of CZTS precursor

In this work, CZTSSe thin film is prepared by selenizing CZTS precursor with Sb and Sb2Se3 doping layer at the bottom. The XRD and Raman results demonstrate that kesterite CZTSSe thin film with preferred crystalline quality is prepared. XPS and EDS results indicate that the inserted Sb and Sb2Se3 atoms do not occupy the lattice of CZTSSe. Both Sb and Sb2Se3 will transfer into semi-liquid phase Sb2Se3 during selenization process, which diffuses into the surface of the absorber from the bottom of the absorber and finally volatilize at the elevated temperature. The semi-liquid phase Sb2Se3 effectively promotes the grain growth of CZTSSe. CZTSSe thin film with Sb2Se3 doping layer has a better crystalline quality than that with Sb doping layer, which exhibited a best PCE of 4.03%, featuring 361.15 mV Voc, 23.19 mA/cm2 Jsc and 48.23% FF.