Efficient Ultrathin Self‐Powered Organic Photodetector with Reduced Exciton Binding Energy and Auxiliary Föster Resonance Energy Transfer Processes

Abstract Recent advances in organic photodetectors (OPDs) have enabled high detectivity, high quantum efficiency, and fast response, due to their broad spectral response, easy processing, compatibility with flexible devices, and cooling‐free operations. The advantages of combining ultrathin and self‐powered OPDs are rarely explored, as technological limitations and lack of knowledge on the underlying mechanisms may lead to low light absorption efficiency and carrier recombination issues. Here, a modification layer‐assisted approach is developed to construct ultrathin self‐powered OPDs with enhanced sensitivity and ultrafast response time performance due to efficient exciton dissociation, energy transfer, and charge extraction processes. Specifically, this strategy enables a reduced exciton binding energy (42.4 meV) for efficient dissociation, as well as an increased dielectric constant of the photosensitive layer that shields undesirable lattice binding effects of photogenerated excitons. As a result, a remarkable device responsivity (0.45 A W −1 ), improved response detectivity (1.25 × 10 12 Jones), and enhanced energy transfer efficiency (78.7%) are observed in the modified ultrathin organic photodetector. These findings illustrate a clear correlation between the exciton dissociation process, photogenerated exciton yields, and energy transfer channels, providing essential insight into the design of efficient ultrathin organic photodetectors.