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

Abstract 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 ⁻¹⁰ A·cm ⁻² and an ultra‐fast response speed, yielding a specific detectivity of 1.27 × 10 ¹⁵ Jones. This work demonstrates a notable advancement in the fabrication of high‐performance perovskite films for applications in photovoltaics and photodetection.