Using Cu₂O/ZnO as Two-Dimensional Hole/Electron Transport Nanolayers in Unleaded FASnI₃ Perovskite Solar Cells

A Pb-free FASnI₃ perovskite solar cell improved by using Cu₂O/ZnO as two-dimensional-based hole/electron transport nanolayers has been proposed and studied by using a SCAPS-1D solar simulator. To calibrate our study, at first, an FTO/ZnO/MAPbI₃/Cu₂O/Au multilayer device was simulated, and the numerical results (including a conversion efficiency of 6.06%, an open circuit potential of 0.76 V, a fill factor parameter of 64.91%, and a short circuit electric current density of 12.26 mA/cm²) were compared with the experimental results in the literature. Then, the conversion efficiency of the proposed FASnI₃-based solar cell was found to improve to 7.83%. The depth profile energy levels, charge carrier concentrations, recombination rate of electron/hole pair, and the FASnI₃ thickness-dependent solar cell efficiency were studied and compared with the results obtained for the MAPbI₃-containing device (as a benchmark). Interestingly, the FASnI₃ material required to obtain an optimized solar cell is one-half of the material required for an optimized MAPbI₃-based device, with a thickness of 200 nm. These results indicate that developing more environmentally friendly perovskite solar cells is possible if suitable electron/hole transport layers are selected along with the upcoming Pb-free perovskite absorber layers.