Highly Stable Perovskite Solar Cells Based on the Efficient Interaction between Pb2+ and Cyano Groups of 4‐Aminophthalonitrile

Abstract Defects present on the top surface of perovskite films have a pronounced detrimental impact on the photovoltaic performance and stability of perovskite solar cells (PSCs). Consequently, the development of effective defect passivation strategies has become key in enhancing both the power conversion efficiency (PCE) and stability of PSCs. In this study, a small molecule material, 4‐Aminophthalonitrile (4‐APN), was introduced as a means to mitigate surface defects within perovskite films. Obviously, 4‐APN effectively passivates the defects at grain boundaries by combining cyano groups (−C≡N) with Pb 2+ , significantly reducing the density of defect states, inhibiting non‐radiative recombination at the interface, and promoting the charge transfer efficiency from the perovskite layer to the hole transport layer. The 4‐APN modification led to a significant upswing in the PCE, while concurrently bolstering the overall device stability. Importantly, the devices on 4‐APN as passivation additive exhibited negligible performance degradation aging for 1200 h.