A Tricyclic Fused‐Ring Molecular Design for Multifunctional Defect Passivation in High‐Performance Perovskite Photovoltaics

High-density defects in perovskite films critically impair the efficiency and operational stability of perovskite photovoltaics. In this study, a multifunctional near-infrared small molecule is designed, featuring a tricyclic electron-deficient core that significantly improves molecular coplanarity and crystallinity. The well-tailed terminal groups capable of passivating Lewis-acid sites, this molecule is employed as an antisolvent additive. This approach induced a synergistic effect encompassing crystallization control, interfacial defect passivation, and energy-level alignment, leading to high-quality perovskite films with superior charge transport properties. Consequently, Tbzf-treated perovskite solar cells achieved a champion power conversion efficiency (PCE) of 25.30%. Moreover, the incorporation of Tbzf enhanced the moisture resistance and overall device stability. Under continuous illumination in a nitrogen atmosphere for 3000 h, the devices retained over 80% of their initial PCE. Notably, the reduction in energetic disorder and trap density effectively suppressed the thermally generated dark current. Photovoltaic photodetectors fabricated using this strategy exhibited an ultra-low dark current density of 5.02 × 10^-10A·cm^-2 and an ultra-fast response speed, yielding a specific detectivity of 1.27 × 10¹⁵ Jones. This work demonstrates a notable advancement in the fabrication of high-performance perovskite films for applications in photovoltaics and photodetection.