Enhancing the stability of perovskite solar cells through surface ring-opening reactions

Stability remains a crucial factor limiting the development of perovskite solar cells (PSCs). Traditional surface passivation layers are typically connected to the perovskite layer through hydrogen bonds. These hydrogen bonds are prone to decomposition under outdoor conditions, failing to protect the perovskite layer and potentially damaging the perovskite structure. These issues severely limit the performance and commercialization of PSCs. To address this challenge, this study utilizes the benzyl glycidyl ether (BGE) molecules to form covalent bonds with the ammonium organic cations on the perovskite surface. The covalent bonds strategy exhibits superior stability, while the reaction also generates hydroxyl and secondary amine groups that passivate defects and suppress ion migration inside the perovskite. This strategy significantly enhances the stability parameters of the PSCs, retaining 62 % of the initial efficiency after 1000 h of continuous illumination, which is higher than that of the control (20 %). Moreover, after being stored in an extreme environment of 75 °C for 200 h, these devices still maintained 80 % of initial efficiency, while the control devices were only 60 %.