Spiro-Buckybowl-Structured Hole-Transporting Materials Toward High-Efficiency and Stable p-i-n Perovskite Solar Cells

In p-i-n structured perovskite solar cells (PSCs), uniform distribution of underlying hole-transporting materials (HTMs) and its interfacial interaction with perovskite defects are crucial for device efficiency and long-term stability. Here, we developed two spiro-buckybowl-shaped HTMs by introducing chalcogen elements (Se and S) into the π-frameworks of sumanene named as Sp-Se and Sp-S, respectively. The unique 3D orthogonal-geometry induced by spiro-fusion reduces intermolecular π-π interactions, hindering molecular aggregation, improving surface coverage and facilitating efficient hole extraction. Additionally, the bowl-shaped π-system plays a critical role in deep-level defects (Pb²⁺, V_I) passivation, leading to effective perovskite crystallization. Specifically, the Sp-S enables superior hole transport and a stabilized buried interface, yielding a champion efficiency of 25.54% (certified at 25.36%) and exceptional operational stability with 92.5% retention over 1250 h under continuous light illumination at 65°C (ISOS-L-2). The spiro-buckybowl molecular structure establishes a new design paradigm for organic semiconductors, offering a versatile platform for perovskite photovoltaics.