In situ Polymerization Induced Seed‐Root Anchoring Structure for Enhancing Stability and Efficiency in Perovskite Solar Modules

Abstract The escape of organic cations over time from defective perovskite interface leads to non‐stoichiometric terminals, significantly affecting the stability of perovskite solar cells (PSCs). How to stabilize the interface composition under environmental stress remains a grand challenge. To address this issue, we utilize thiol‐functionalized particles as a “seed” and conduct in situ polymerization of 2,2,3,4,4,4‐hexafluorobutyl methacrylate (HFMA) as a “root” at the bottom of the perovskite layer. In this process, the thiol group acts as the initiation site for the polymerization of HFMA, while the fluorine groups in HFMA firmly anchor the organic cations of the perovskite through multiple hydrogen bonds. This strategy resembles how seeds take root in soil to prevent soil erosion. This bionic seed‐rooting structure effectively stabilizes the stoichiometry of the perovskite, thus suppressing the escape of organic cations. As a result, the perovskite films with seed‐rooting structures exhibit enhanced stability under harsh vacuum thermal conditions (150 °C, <10 Pa). The resulting PCS achieves an efficiency of 25.64 % and a 22.4 cm 2 module efficiency of 22.61 %. After 1300 hours of 1‐sun illumination at 85 % relative humidity and 65 °C (ISOS−L‐3 protocol), the perovskite solar module maintains 90 % of its initial efficiency.