Humidity Resistant Air‐Processing of Large Area Perovskite Photovoltaic Modules via Dual Interaction‐Induced Moisture Shielding

ABSTRACT Formamidinium (FA)‐based perovskite solar cells (PSCs) hold potential for industrialization due to their high power conversion efficiency (PCE), yet their fabrication relies heavily on inert gas environments, primarily constrained by their intrinsic moisture sensitivity. To enable humidity‐resistant air‐processing of large‐area perovskite modules, we introduce isobutylamine hydrochloride (iBACl) as a multifunctional additive, leveraging a dual interaction‐induced moisture shielding to address the above challenges. We found that the electrostatic interactions of iBACl with Pb 2+ and I − , as well as the probable formation of FA‐iBA + complexes, render a less energetically favorable bonding between water and perovskite precursors, thereby suppressing these water‐assisted sub‐optimal phase transitions. Additionally, iBACl enhances the quality of perovskite by reducing trap density, thus prolonging carrier lifetime and lowering residual stress. Our strategy enables air‐fabrication across a wide humidity window (0%–40% relative humidity). Specifically, blade‐coated mini‐modules (12.80 cm 2 ) achieve a PCE of 22.16%, while slot‐die‐coated large‐area modules (653.9 cm 2 ) obtain a PCE of 20.05% (certified 19.16%). Unencapsulated devices retain 92% of their initial efficiency after 1000 h of dark storage under 30%–40% RH (shelf stability), significantly outperforming the control devices (81%). This work provides a viable route for the scalable air‐processing of FA‐based perovskite modules.