Bimolecular amine vapor passivation for efficient perovskite solar cells based on blade-coated FAPbI3

Formamidinium lead triiodide (FAPbI₃)-based perovskite solar cells (PSCs) are highly promising due to their optimal bandgaps and high efficiencies, but suffer from instability and performance-limiting defects. Conventional solution-based passivation methods face challenges in surface uniformity and scalability. Here, a bimolecular amine vapor passivation (BAVP) strategy using 2-phenylethylamine (PEA) and ethylenediamine (EDA) is introduced to effectively passivate blade-coated FAPbI₃ films fabricated under ambient low-humidity conditions, with excellent surface uniformity. PEA coordinates with Pb²⁺ to mitigate surface defects, while EDA reacts preferentially with FA⁺, optimizing energy alignment at the perovskite/C₆₀ interface for enhanced charge extraction. Consequently, BAVP-treated PSCs achieve a champion efficiency of 25.2%. Remarkably, unencapsulated devices retain 99.4% of their initial efficiency after 2616 hours of thermal aging at 85 °C in N₂ (ISOS-D-2), and 97.5% after 500 thermal cycles (ISOS-T-1) in N₂. Furthermore, perovskite solar modules (PSMs) fabricated using the BAVP method attain an efficiency of 21.3% over a total area of 6.25 cm², surpassing the 18.7% obtained using the traditional solution-based passivation. These results demonstrate the significant potential of the BAVP strategy in advancing the efficiency, stability and scalability of PSCs.