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

ABSTRACT 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 (Pb 2+ , 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.