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.