High‐Speed and Low‐Noise Monolithic Organic Image Sensors via Phase‐Segregation Control and Interface Engineering

ABSTRACT Organic photodetectors (OPDs) are promising for flexible and large‐area imaging, but simultaneously achieving a fast response and high sensitivity remains limited by the intrinsic trade‐off between dark‐current suppression and charge extraction. Here, we effectively mitigate this limitation through a structurally decoupled OPD architecture integrating a kinetically engineered homogeneous ZnPc:C 60 bulk heterojunction with an atomically thin (0.90 nm) Al 2 O 3 tunneling interlayer. The homogeneous bulk heterojunction suppresses phase segregation and defect‐assisted recombination while maintaining efficient carrier extraction, whereas the ultrathin Al 2 O 3 layer selectively suppresses the leakage current with minimal impact on charge extraction. By minimizing the mutual interference between these functions, the device enables noise suppression and carrier extraction synergistically. As a result, the OPD achieves a high EQE of 69.5%, a low dark‐current density of 2.10 × 10 −8 A cm −2 at −0.5 V, a peak detectivity of 2.51 × 10 1 3 Jones, and an ultrafast response time of 30 ns. Transmissive photoplethysmography and a 12.8 × 12.8 mm 2 large‐area image sensor are also demonstrated. This work establishes a mechanism‐guided structural engineering strategy for developing high‐performance organic photodetectors.