Spontaneous Repair of Self‐Assembled Monolayer Desorption Vacancies for Efficient and Stable Wide‐Bandgap Perovskite Solar Cells

ABSTRACT Wide‐bandgap perovskite solar cells are promising for tandems, but their performance and stability are limited by the desorption of self‐assembled monolayers (SAMs) at the buried interface. Here, we introduce a bifunctional additive, 1‐carboxymethyl‐3‐methylimidazolium chloride (CMMICl), that spontaneously migrates to and repairs SAM vacancies during perovskite formation. CMMICl forms π–π interactions with desorbed SAMs to reconstruct a dense mixed monolayer and acts as molecular bridges for efficient hole extraction. Concurrently, it regulates crystallization to yield high‐quality films with reduced strain and suppressed halide segregation. These effects substantially suppress non‐radiative recombination, enabling a power conversion efficiency of 20.50% and an open‐circuit voltage of 1.354 V for 1.79 eV bandgap devices, with over 90% efficiency retained after 690 h of maximum power point tracking. This work provides a generalizable interface‐repair strategy for advancing perovskite optoelectronics.