Unlocking the Full Potential of Polydentate Self‐Assembled Molecules in Perovskite Solar Cells: Co‐Deposition Versus Pre‐Deposition

ABSTRACT Self‐assembled molecules (SAMs) are widely employed for buried interface engineering in perovskite solar cells (PSCs), typically through pre‐deposition onto substrates prior to perovskite coating. While recent efforts focus on developing polydentate SAMs to strengthen chemical interactions, the restricted contact between pre‐deposited SAMs and perovskite precursors largely constrains their potential to modulate perovskite crystallization. Co‐deposition of SAMs with perovskite precursors presents a streamlined alternative to circumvent this constraint, yet fundamental questions such as SAM additive distribution and passivation efficacy remain unclear. Herein, a systematic comparison between these two strategies is conducted in n‐i‐p structured PSCs, based on a polydentate SAM N‐(2‐Acetamido)iminodiacetic acid (ADA). Our results reveal identical SAM distribution/orientation and comparable defect passivation efficacy at the buried interface for both strategies. Crucially, co‐deposition facilitates extensive interactions between SAMs and perovskite precursors during crystallization, significantly modulating crystal growth kinetics with enlarged grains and suppressed bulk defects. Consequently, optimized co‐deposition devices achieved a champion power conversion efficiency of 25.81% with a T 80 lifetime exceeding 4000 h under ISOS‐L‐1I protocol. The successful extension of the co‐deposition strategy from ADA to other polydentate SAMs further underscores its universality across diverse molecular systems. This work bridges the knowledge gap in the fundamental comprehension of polydentate SAM additives and unveils their previously overlooked potential in crystallization control, offering a promising pathway toward simplified and high‐performance perovskite photovoltaics.