Determination of Suitable Transport Layers in Light of Interface Defect States in MASnX3‐Based Perovskite Solar Cell

Interface defects are crucial to improve the perovskite solar cell stability. This study investigates and determines the suitable electron transport layer (ETL) for Sn‐based perovskite solar cells. The investigation finds that carriers capture cross‐sectional area greatly impacts photovoltaic performance, and the optimum value is 1 × 10 −25 cm 2 . A low trap density of 10 12 does not play a significant role, but an interface defect density of 10 17 located near the valence band edge at the ETL/absorber interface has the most detrimental effect. In structure, defect states ( E t ) near the valence band edge of PCBM/CH 3 NH 3 SnI 3 /NiO and WO 3 /CH 3 NH 3 SnI 3 /NiO devices have a higher destructive impact compared to TiO 2 /CH 3 NH 3 SnI 3 /NiO. The study also finds that absorber bulk defects and the interface defects in the ETL/absorber layer are the most sensitive to device performance. This detrimental impact on cell performance can be avoided by reducing the capture cross‐sectional area and maintaining a low trap density.