Real-Time Pulse Monitoring and Analysis Realized by Organic Near-Infrared Photodetector with Detection Region Up to 1550nm

Near-infrared organic photodetectors (NIR-OPDs) nowadays have become a hot research filed because of their advantages such as flexibility, solution-processed preparation and low cost. However, in the region of NIR window II (900–1700 nm), as an important and key role in biological detection and imaging due to its better penetration in tissues, the relevant research results are still insufficient. Here, we construct a binary bulk heterojunction by utilizing non-fullerene narrow band gap materials, that is employing PPHTQ:IEICO-4Cl hybrid film as photosensitive layer. The dark current of the NIR-OPD we prepared is low to 3.66×10 ⁻¹¹ A when no bias is applied. Meanwhile, a good responsivity of approaching 100 mA/W is achieved. Therefore, a nice detectivity which is over 10 ¹² Jones at 940 nm in near-infrared window II is realized. In the view of the high-performance characteristics of the device and the well penetration characteristics at 940 nm in NIR window II, we carry out real-time monitoring of human being pulse behaviors. From the obtained arterial signals, we can get the heart rate, cardiac cycle, diastolic period, the systolic period and dicrotic notch as the key physiological parameters. Our NIR-OPD provides a new strategy for building high-performance near-infrared window II organic photodetectors and its significant applications of signal detection in biological or human body.