Surfactant Induces Uniform and Stable Self‐Assembled Monolayers for High‐Performance Wide‐Bandgap Perovskite Solar Cells

ABSTRACT Self‐assembled monolayers (SAMs) have been extensively studied in perovskite solar cells (PSCs). Nevertheless, the aggregation tendency of SAM molecules results in non‐uniform deposition and inadequate substrate coverage, thereby severely impeding device performance. Herein, we introduce a multifunctional additive, nonafluorobutane‐1‐sulfonic acid (PFBS), to actively regulate the growth of SAM layers. Our investigations reveal that PFBS suppresses the self‐aggregation of SAM molecules through hydrogen bonding and steric disruption, thus promoting their dispersion in the solution and facilitating the exposure of anchoring groups. The PFBS‐modified SAM exhibits improved coverage, robustness, and interfacial energy‐level alignment. Furthermore, PFBS effectively passivates interfacial defects, reduces non‐radiative recombination, and promotes the growth of high‐quality perovskite film. Consequently, the PFBS‐optimized PSC with a 1.68 eV bandgap delivers a champion power conversion efficiency (PCE) of 24% and significantly enhanced stability. This work presents an additive‐induced ordering strategy, providing a scalable route for high‐performance PSCs and tandem photovoltaics.