Vacuum‐Evaporated Perovskite and Interfacial Modifier for Efficient Perovskite Solar Cells

Abstract Surface passivation of the perovskite layer is crucial for enhancing the photovoltaic performance of perovskite solar cells (PSCs). Vacuum evaporation is a scalable solvent‐free method for depositing a uniform and homogenous thin layer with better control of film thickness. While the use of the vacuum‐deposition method to obtain high‐quality perovskite thin films is recently adapted, the evaporation of organic additives for surface passivation of the perovskite layer has not been widely studied. In this work, a vacuum evaporation method is introduced to uniformly deposit a novel multifunctional organic salt, 2‐chlorophenethylamine pentafluorobenzene sulfonate (2‐ClPEAPf), onto a perovskite surface. It is observed that 2‐ClPEAPf not only effectively passivates the interfacial defects but also prevents moisture invasion into the perovskite film. As a result, planar n–i–p PSCs exhibit maximum PCE up to 25.16% with an aperture area of 0.1 cm 2 and PCE of 24.00% (certified) on an active area of 1.0 cm 2 . In addition, the 0.1 cm 2 device with vacuum‐evaporated 2‐ClPEAPf reveals enhanced operational stability maintaining 92.5% of its initial efficiency after 800 hours of continuous light irradiation.