Inorganic Lead-Free B-γ-CsSnI3 Perovskite Solar Cells Using Diverse Electron-Transporting Materials: A Simulation Study

B-gamma-CsSnI3 perovskite solar cells (PSCs) are simulated employing diverse electron-transporting layers (ETLs, including TiO2, ZnO, SnO2, GaN, C-60, and PCBM), and a comparative study has been made. Both regular and inverted planar structures are simulated. Effects of the thickness of absorbers and ETLs, doping of ETLs, and interface trap states on the photovoltaic performance are studied to optimize the device structures. The regular structures have larger short-circuit current density (J(sc)) than the inverted structures, but the inverted structures have larger fill factor (FF). All of the simulated optimal PSCs have similar opencircuit voltages (V-oc) of similar to 0.96 V. The PSCs with TiO2 ETLs have the best photovoltaic performance, and the optimum structure exhibits the highest efficiency of 20.2% with a Voc of 0.97 V, Jsc of 29.67 mA/cm(2), and FF of 0.70. The optimal PSCs with ZnO, GaN, C-60, and PCBM ETLs exhibit efficiencies of 17.88, 18.09, 16.71, and 16.59%, respectively. The optimal PSC with SnO2 ETL exhibits the lowest efficiency of 15.5% in all of the simulated PSCs due to its cliff-like band offset at the SnO2/CsSnI3 interface. Furthermore, the increase of interface trap density and capture cross section is found to reduce the photovoltaic performance of PSCs. This work contributes to designing and fabricating CsSnI3 PSCs.

Automated summary

In this study, diverse electron-transporting layers were simulated for optimizing B-gamma-CsSnI3 perovskite solar cells, with those using TiO2 ETLs showing the best photovoltaic performance with an efficiency of 20.2%. Interface trap states and band offset at interfaces were found to significantly impact the photovoltaic performance of the PSCs.