Organotrifluoroborate‐Driven Phase Stabilization and Defect Suppression for Wide‐Bandgap Perovskites

Wide‐bandgap perovskite solar cells are indispensable top absorbers for high‐efficiency all‐perovskite tandems, yet their deployment is impeded by halide phase segregation and non‐uniform crystallization that erode voltage, efficiency, and stability. Here we introduced a simple, multifunctional organotrifluoroborate additive, trifluoro (pyrrolidin‐1‐ium‐1‐ylmethyl) borate. Trifluoro (pyrrolidin‐1‐ium‐1‐ylmethyl) borate preferentially enriched at buried interfaces due to its asymmetric charge distribution and interfacial affinity, a spatial distribution that simultaneously achieved defect passivation and phase separation suppression in wide‐bandgap perovskites. Trifluoro (pyrrolidin‐1‐ium‐1‐ylmethyl) borate regulated halide migration through Pb–F coordination, passivated defects, and formed amine‐halide hydrogen bonds with enhanced affinity for Br, thereby improving crystallization kinetics and enhancing film quality. The resulting wide‐bandgap perovskite solar cells with a 1.79 eV bandgap delivered a power conversion efficiency of 20.80%, with an open‐circuit voltage as high as 1.384 V, maintaining 80% of their initial efficiency after 800 hours of continuous operation. This study provides a chemically targeted bulk‐interface synergistic regulation strategy for defect passivation and phase stability research in wide‐bandgap perovskites.