Pre‐Anchored Ionic Bond Mediators Enabling Controllable Monolayer Assembly for High‐Performance Perovskite Solar Cells and Modules

Abstract Self‐assembled monolayer (SAM) has emerged as an indispensable hole‐selective contact for high‐efficiency perovskite solar cells (PSCs). However, the formation of dense, uniform SAMs via wet deposition poses challenges due to two thermodynamically feasible yet competing processes: the self‐aggregation of SAM molecules and chemisorption‐driven substrate anchoring. Herein, a rapid and controllable strategy for SAM assembly is presented, enabled by pre‐adsorbed ionic bond mediators. The pre‐anchored arginine (Arg) molecules on nickel oxid (NiO x ) can weaken the amphiphilic nature of SAM molecules through ionic bond interaction, while also acting as steric barriers, thereby suppressing the self‐aggregation of SAM molecules. This strategy is compatible with both spin‐coating and blade‐coating techniques, enabling rapid and controllable assembly of high‐quality SAM of [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) butyl] phosphonic acid. Moreover, the polar guanidinium tail of Arg passivates defects at the buried perovskite interface while strengthening interfacial coupling with the perovskite layer–enhancing both mechanical stability and electrical contact. Benefiting from these synergistic effects, the PSCs achieve high PCEs of up to 26.67% and 21.05% for small‐area devices (active area: 0.049 cm 2 ) and large‐area modules (active area: 64.68 cm 2 ), respectively. Notably, the devices exhibit exceptional operational stability, retaining 93% of their initial PCE after 1700 h of maximum power point tracking under the ISOS‐L‐2 protocol.