Broadband Photodetectors Enabled by Perovskite/Organic Bulk Heterojunction for Non‐Contact Monitoring of Heart Rate and Blood Oxygen Saturation

ABSTRACT Non‐contact vital sign monitoring relies on high‐sensitivity photodetectors to extract faint physiological signals. Although metal‐halide perovskites are successfully exploited for high‐performance optoelectronics, the inherent bandgap of traditional lead halide perovskites prevents near‐infrared physiological monitoring, simply incorporating narrow‐bandgap organic materials to solve this introduces severe interfacial recombination and carrier transport bottlenecks that extinguish faint pulse signals. Here, we propose an interfacial engineering strategy, utilizing both solvent vapors assisted annealing and donor and acceptor interface density optimization, to construct a perovskite/organic bulk heterojunction (BHJ) photodetector. The incorporated F8IC and PTB7‐Th BHJ compensates for the near‐infrared absorption deficiency and modulates carrier transport dynamics, thereby greatly suppressing interfacial nonradiative recombination and substantially mitigating both dark current density and device noise. Enabled by this suppressed noise, the device exhibits an ultralow detection limit of 1.37 × 10 −9 W/cm 2 and a large linear dynamic range of 180 dB. These metrics yield state‐of‐the‐art performance among perovskite‐based photodetectors. Taking advantage of its broad spectral response and superior weak‐light sensitivity, we demonstrate the utility of this detector in dual‐band non‐contact heart rate and blood oxygen monitoring. This work provides an interfacial engineering pathway to advance high‐performance broadband devices for health monitoring.