Rationally tailored passivation molecules to minimize interfacial energy loss for efficient perovskite solar cells

Abstract Labor-intensive, trial-and-error methods are frequently employed for modifying the perovskite surface to mitigate trap defects. There is an urgent need for rationally designed and efficient molecular passivators. To address the performance and stability challenges caused by defects in polycrystalline perovskite, we have rationally designed and tailored passivation molecules, 4-(trifluoromethyl)benzoic anhydride (TFBA), ethyl 4-(trifluoromethyl)benzoate (TFB), and 4-(trifluoromethyl)benzoic acid (PTF), to minimize interfacial energy loss and modulate the bandgap alignment for achieving efficient perovskite solar cells (PSCs). These molecules could target the perovskite surface defects, particularly Pb–I antisite defects, with the –COOH and trifluoromethyl functional groups at the edges. Among them, PTF exhibited superior passivation performance by coordinating its carboxyl group with Pb 2+ , effectively suppressing non-radiative recombination. Additionally, the fluorine sites in these molecules corrected lattice distortions and stabilized the perovskite structure through hydrogen bonding with MA/FA cations, reducing ion migration, and enhancing moisture resistance. As a result, PTF-modified PSCs achieved an efficiency of 25.57% and maintained over 85% of their initial efficiency after 1 600 h of aging. This study provides a clear pathway for optimizing passivation strategies through rational molecular design.