High Performance Near Infrared Organic Photodetectors Realized by Non‐Fullerene Acceptors with Reduced Static Energetic Disorder

Abstract Organic photodetectors (OPDs) show promising application in environmental monitoring and wearable sensors, however, their detectivity in the near‐infrared (NIR) regime is limited. This is linked with the high energetic disorder of organic semiconductors. In this work, non‐fullerene acceptors (NFAs) with different conjugation frameworks are assembled into OPDs, and their dark current density ( J d ) and specific detectivity ( D * ) are correlated with structure. It is found that the expansion of conjugation backbone can enhance the intermolecular interactions of NFAs toward ordered molecular packing, nevertheless it also induce the formation of multi‐crystalline structure that leads to increased energetic disorder. As the results, dual‐extended NFA C5Qx‐B6F with rigid backbone and torsional end group forms a preferential face‐on molecular packing with decreased lattice mismatches, resulting in reduced energetic disorder and density of state. C5Qx‐B6F based OPD not only enables an ultra‐low J d of 4.3 × 10 −11 A cm− 2 A cm −2 at –0.1 V with remarkable specific detectivity of 6.9 × 10 13 Jones at 800 nm, but also can be utilized as the third component to suppress the energetic disorder of a near‐infrared PTB7‐Th:BTPV‐C9OD system, achieving an unprecedented D * over 10 13 Jones at 1000 nm, which is among the highest value for solution processed NIR‐OPDs.