Abstract Near‐infrared (NIR) organic photodetectors (OPDs) play a vital role in various fields, including biomedical imaging, optical communications, and night vision. However, limited by the energy gap law, the non‐radiative recombination rate increases exponentially as the material's bandgap decreases, which restricts the development of high‐performance OPD. Herein, novel A‐π‐D‐π’‐A‐type non‐fullerene acceptors (NFAs) is developed by effectively modulating the degree of twist in the conjugated backbone, yielding two half‐twisted‐half‐planar NFAs: h‐ITT‐4F and h‐ITT‐4Cl. The fluorinated molecule h‐ITT‐4F demonstrates optimized film morphology and crystalline intensification compared to its chlorinated counterpart h‐ITT‐4Cl. The integrated advantages confer upon PTB7‐Th:h‐ITT‐4F‐based OPDs suppressed nonradiative energy loss, enhanced charge transport, and reduced trap density. This leads to a self‐powered OPD featuring an ultra‐low dark current density (1.65 × 10 −10 A cm −2 ), notable specific detectivity ( D * sh surpassing 10 13 Jones across 400–1000 nm), and a −3 dB cutoff frequency over 200 kHz. Such metrics rank among the top‐performing results reported to date. Meanwhile, the OPDs demonstrate real‐time photoplethysmography monitoring, resolving systolic/diastolic features, showcasing their potential in biohealth sensing. These findings highlight a promising molecular design strategy for narrow‐bandgap NFAs, enabling minimized non‐radiative recombination and optimized morphology, and offering substantial potential for high‐performance NIR OPDs in biomedical sensing applications.
Yang et al. (2025) studied this question.