Numerical Simulation of Planar Heterojunction Perovskite Solar Cells Based on SnO₂ Electron Transport Layer

The perovskite solar cells attracted great attention owing to their low cost and high performance. SnO2 as electron transport layer has been mostly used in the perovskite solar cells due to its excellent properties, such as good antireflection, suitable band edge position, and high electron mobility. In this study, the effects of band offsets, electrode work function, perovskite layer thickness, and electron mobility of SnO2 were investigated on the performance of perovskite solar cells. According to the results, the power conversion efficiency (PCE) was first enlarged with the increasing thickness of perovskite layer and then became saturated when the perovskite layer thickness was larger than 500 nm. The optimum conduction band offset (CBO = Ec_ETL – Ec_perovskite) and valence band offset (VBO = Ev_HTL – Ev_perovskite) were −0.1 to 0.4 eV and −0.1 to 0.1 eV, respectively. The optimal PCE was achieved when cathode electrode work function (Φcathode) was larger than −4.8 eV and anode electrode work function (Φanode) was smaller than −5.2 eV due to increased built-in voltage and carrier extraction. Moreover, the optimal PCE can be obtained when electron mobility of SnO2 was greater than 10–3 cm2/(V s). This work would provide guidance to develop high performance perovskite solar cells.