An investigation of defects, band-offset, and Schottky barrier height for boosting the performance of formamidinium mixed cation mixed halide based perovskite solar cell: Theoretical approach

The phase stability of FAPbI3 based perovskite solar cells (PSCs) has been a serious concern. The black stable α-phase of FAPbI3 transits into a hexagonal non-perovskite yellow phase because of a large tolerance factor (>1). Many studies reported that the incorporation of Cs+ and Br− ions into the FAPbI3 could tune the tolerance factor resulting in improved thermal and phase stability of the device. In this work, we have optimized FA0.85Cs0.15Pb(I0.85Br0.15)3(FAPbIBr) based PSCs using various organic and inorganic charge transport layers (CTLs). This work aims to explain the collection and transportation of charge carriers at perovskite/CTL and hole transport layer (HTL)/back contact interfaces by optimizing energy band levels. Additionally, the impact of Schottky barrier height at the HTL/back contact interface has been investigated. Simulation results reveal that ZnO (as ETL) and SrCu2O2(as HTL) demonstrate superior efficiency of 19.02% among all the investigated CTLs.