Rationally Designed Bilayer Passivation Strategy for High‐Performance Vacuum‐Processed Perovskite Solar Cells

Vacuum thermal evaporation is a promising scalable fabrication route for perovskite solar cells (PSCs) due to its precise control over film thickness and compatibility with large‐scale production. However, unlike solution‐based methods, vacuum‐processed perovskite films undergo complex solid‐state reactions that often cause non‐uniform crystallization and a high density of surface defects such as halide vacancies and uncoordinated Pb 2+ ions. Herein, we report a rationally designed bilayer passivation strategy, termed “Anchor‐and‐Seal”, to mitigate these surface defects and optimize interfacial energy level alignment. By sequentially applying ethylenediammonium diiodide (EDAI 2 ) and 4‐methoxy‐phenethylammonium‐iodide (4MeO‐PEAI), we effectively passivate defects through strong hydrogen bonding and Lewis base coordination. While EDAI 2 serves as a rigid anchoring agent, the flexible 4MeO‐PEAI molecules infiltrate remaining nanometer‐scale voids, resulting in broadly uniform passivation and reduced non‐exciton recombination. Furthermore, the bilayer passivation induces an upward shift of the Fermi level, thereby enhancing charge extraction. Consequently, vacuum‐processed p‐i‐n PSCs achieve a champion power conversion efficiency of 20.59% with significantly enhanced open‐circuit voltage, and exhibit significantly enhanced stability, retaining 94% of their initial efficiency after 1000 h in an inert atmosphere. Notably, a lab‐scale mini‐module (2.4 cm 2 ) achieves a PCE of 18.46%, demonstrating the scalability and commercial potential of this approach for vacuum‐deposited photovoltaics.