Specific detectivity-oriented low-noise management in organic photodetectors

The need to detect faint light signals with unparalleled precision is redefining organic photodetectors (OPDs) and unlocking their transformative applications in biosignal monitoring, optical communication, and quantum-level photodetection. The specific detectivity (D*) is an essential metric in such scenarios that captures the ability of an OPD to extract weak signals from noise and is a function of the active area, bandwidth, and noise-equivalent power of the device. This review reframes the pursuit of an ultrahigh D* by targeting noise current suppression, -a formidable issue in which shot, thermal, flicker, and generation-recombination noise sources combine to obscure signals. First, the complexities of noise are discussed, then various strategies for addressing its causes are explored in terms of charge injection, interfacial traps, and material defects. These strategies include: precisely tailoring active layers to mitigate trap-assisted recombination and charge generation, selectively optimizing transport layers to mitigate interfacial defects at the electrode interface and block unwanted injection currents, and applying architectural innovations such as tandem and nanostructured designs that transcend single-junction paradigms. By combining mechanism-driven insights with a critical appraisal of current frontiers, this review highlights untapped opportunities and promising strategies for developing OPDs with unprecedented sensitivity and performance.