Dual-acceptor alloy model delivers high detection performance of organic NIR detectors for real-time arterial pulse monitoring

Abstract

Near-infrared organic photodetectors (NIR-OPDs) have significant potential in the fields of human sign monitoring, industrial defect detection, and military. We propose a method to construct high-performance NIR-OPDs by introducing narrow-band acceptor materials with very similar structures in bulk heterojunctions (BHJs) so that they form an alloy model during the film formation process, which in turn promotes the generation and dissociation of photogenerated excitons to achieve high-performance NIR detectors. Here, we choose the narrow-band materials IEICO-4F and IEICO-4Cl as dual-acceptors and PTB7-Th as the donor to construct NIR-OPDs. Benefiting from the alloy model formation, the dark current of the device is significantly suppressed compared with the binary control, while the photocurrent of the device is enhanced. The optimized NIR-OPD achieved a detectivity of more than 2.6×1012 Jones at -0.1V bias. With the optimized device performance, we can clearly monitor the human arterial pulse information, and the phases of the cardiac cycle of the heart can be accurately identified. This work demonstrates a new method for constructing highperformance NIR-OPDs and shows great potential for contactless human arterial pulse monitoring.