Synthesis of a Butterfly‐Shaped π‐Extended Dibenzazepine and Its Application in Interfacial Engineering for High‐Performance Perovskite Solar Cells

ABSTRACT Self‐assembled monolayers (SAMs) are key interfacial modifiers for inverted perovskite solar cells (IPSCs), yet their design is often constrained by a trade‐off between suppressing molecular aggregation and maintaining efficient charge transport. Here we introduce a π‐extended nonplanar molecular design to decouple interfacial morphology control from electronic coupling. Two tetracene‐fused SAM molecules, tetraceno‐fused carbazole phosphonic acid (PATCz) and tetraceno‐fused dibenzazepine phosphonic acid (PATDBAz), were synthesized via dehydrocyclization. While PATCz forms a helicene‐like twisted structure, PATDBAz adopts a butterfly‐shaped nonplanar geometry that enables Butterfly‐shaped π‐extended “wings” to form effective intermolecular π – π stacking while preventing excessive aggregation. This structural feature promotes ordered interfacial assembly, improved energy‐level alignment, and efficient hole transport. Consequently, PATDBAz‐based IPSCs achieve a champion power conversion efficiency of 26.47% and retain 97.5% of their initial efficiency after 1000 h under International Summit on Organic Photovoltaic Stability light‐soaking level 1 (ISOS‐L‐1) conditions. This work highlights π‐extended nonplanar frameworks as an effective strategy for designing high‐performance SAMs in perovskite photovoltaics.