Homogenizing Fullerene Contacts by Supramolecular Host–Guest Assembly for Stable Perovskite Solar Cells

ABSTRACT Fullerene and its derivatives are widely adopted as electron transport layers (ETLs) in high‐performance perovskite solar cells (PSCs). However, fullerene materials are prone to aggregation and rearrangement under environmental stress, which acts as one of the critical factors restricting the long‐term operational stability of devices. Here, we report a host–guest supramolecular assembly strategy using rigid triptycene (TPC) molecules to stabilize fullerene‐based ETLs. The [6,6]‐phenyl‐C 61 ‐butyric acid methyl ester (PCBM)–TPC host–guest interaction enables the spatial isolation and noncovalent immobilization of PCBM cages, which suppresses the thermal‐driven aggregation, crystallization, and morphological variation of PCBM layers. The resulting inverted PSCs achieve a champion power conversion efficiency of 26.83%, with 96.0% efficiency retention after 1000 h of 85°C thermal aging and 92.3% retention after 1000 h of 85°C photothermal maximum power point tracking. This work offers a supramolecular solution for high‐stability optoelectronic devices.