Energy level engineering of charge selective contact and halide perovskite by modulating band offset: Mechanistic insights

Mixed cation and anion based perovskites solar cells exhibited enhanced stability under outdoor conditions, however, it yielded limited power conversion efficiency when TiO2 Spiro-OMeTAD were employed as electron hole transport layer (ETL/HTL) respectively. The inevitable interfacial recombination of charge carriers at ETL/perovskite perovskite/HTL interface diminished the in planar (n-i-p) perovskite cells. By employing computational approach for uni-dimensional device simulator, effect band offset on both interfaces was investigated. We noted that acquired cliff structure conduction minimum ETL lower than perovskite, thus maximized recombination. However, if is higher a spike formed, which improve performance cell. An optimum value allows to reach 25.21%, with an open circuit voltage (Voc) 1231 mV, current density Jsc 24.57 mA/cm2 fill factor 83.28%. Additionally, we found beyond value, large could decrease performance. With optimized energy level thickness mixed-perovskite 26.56% can be attained. Our results demonstrate detailed understanding about tuning between selective layers how improvement PV achieved by adjusting offset.