All-Vacuum-Deposited Bifacial Cu2ZnSnSe4 Photovoltaic Cells with Sputtered Cd-Free Buffer Layer

By depositing metal precursors on fluorine-doped tin oxide substrates using evaporation and postselenisation and modifying the number of stacked metallic precursor layers, this study systematically analysed the effect of cation changes on the absorber layer and the solar cell properties of Cu2ZnSnSe4 (CZTSe). Furthermore, in this study, an all-vacuum method was adopted to prepare a cadmium-free bifacial CZTSe solar cell and conducted damp heat tests on the device. The findings indicate that the increase in the number of stacked metallic precursor layers suppresses secondary phase generation, thereby enhancing the film performance and bifacial solar cell characteristics. The cadmium-free bifacial CZTSe solar cell prepared in this study exhibited the efficiency of 4.13% under bifacial incident light. Moreover, the degradation of the device was effectively mitigated in the damp heat tests compared with previously reported devices with metal substrates. These findings can provide new directions for research and lead to novel applications for CZTSe solar cells in the future.