Defect‐Induced Symmetry Breaking Activates Fullerene Acceptors for Self‐Powered Organic Photodetection

ABSTRACT Pristine C 60 suffers from symmetry‐induced forbidden transitions, resulting in limited visible‐infrared photoresponse and restricting its application in organic photodetectors (OPDs). Here, we report a biomass‐assisted thermal reconstruction strategy to break the intrinsic symmetry of C 60 through heteroatom‐induced defect engineering. By calcining chitosan oligosaccharide with C 60 , a novel fullerene derivative (CC) was obtained, exhibiting reconstructed electronic states and narrowed energy gaps. Incorporating CC into the P3HT active layer induces intermediate states that facilitate low‐energy photogeneration, overcoming the limited visible‐light response of conventional C 60 ‐based OPDs to enable broadband photoresponse. The optimized P3HT: CC OPD achieved a detectivity of 1.15 × 10 13 Jones, an ultra‐high on/off ratio of ≈3 × 10 6 , and an outstanding linear dynamic range of 108.3 dB, rivaling silicon or PCBM‐based devices. Benefiting from enhanced broadband absorption and optimized carrier transport, the CC devices further demonstrate excellent operational stability and potential for flexible biomimetic imaging and wireless optical communication. CC also exhibits high versatility in OPDs incorporating other organic donor materials. This work provides a sustainable and low‐cost strategy for reactivating fullerene‐derived materials toward next‐generation broadband organic optoelectronics.