Balanced Molecular Interactions with Mild Dipole Moment for Intermediate Suppressing in High Performance Antisolvent‐Free Regular <i>α</i> ‐FAPbI ₃ Solar Cells

Abstract

ABSTRACT It is promising to fabricate perovskite solar cells (PSCs) without antisolvent, but its intrinsic slow nucleation and unhomogenized growth are often accompanied by enormous solvated intermediates, which divert the α ‐FAPbI 3 crystallization and potentially restrict the acquisition of high‐performance PSCs. Herein, we present a balanced molecular interaction strategy using additives with mild dipole moments of around 1.9 Debye to suppress solvated intermediates. By systematically scrutinizing symmetric dimethyl isophthalate (DMIP) derivatives with varied groups (5‐H, ─F, ─Cl, ─Br, ─NH 2 , ─OCH 3 , and ─OH), the optimum phase‐evolution process is obtained with fluorine substituents. The balanced molecular interactions with Pb 2+ coordination, FA + hydrogen bonding, and I − between solvents and additives, significantly shorten t d‐α (the time for α ‐phase start to dominate) from &gt; 150 to 23 s, enabling the faster and complete phase transformation to high‐quality α ‐FAPbI 3 . Consequently, we obtained a high‐power conversion efficiency up to 26.28%, representing the highest reported efficiency for antisolvent‐free regular PSCs based on pure FAPbI 3 absorbers. Moreover, the device maintains 93.7% of its initial efficiency after 1500 h aging at 85°C and retains 90% after 1000 h maximum power point tracking, demonstrating proper stability through this strategy.