High-Performance Self-Powered Organic Photodetectors for Near-Infrared Weak Light Detection

Near-infrared (NIR) organic photodetectors (OPDs) have significant potential in the development of night vision, optical communication, and image-sensing systems. However, most of them require external energy consumption, and particularly the investigation focuses on weak light detection in the NIR region at or beyond 1000 nm remains limited. In this study, self-powered OPDs with a PCE10:COTIC-4F organic bulk heterojunction as the photoactive layer are designed, which are capable of responding to an ultra-weak light signal of 6.3 pW cm-2 at 1000 nm, demonstrating a significantly low level in comparison to currently reported OPDs. In addition, the OPDs also exhibit other outstanding photodetection performance, including large Ilight/Idark ratio of 3.47 x 106, high responsivity of 1.50 A W-1, and detectivity of 3.17 x 1013/1.80 x 1011 Jones (evaluated by dark/noise current methods). Furthermore, the unencapsulated OPDs demonstrate almost no obvious attenuation in the air during a 224-day test and in the aging environment during a 67-day test. More importantly, the self-powered OPDs demonstrate the potential for flexible electronics, NIR imaging, and NIR selectivity with visible-blind characteristic. The development of self-powered OPDs provides an accessible and viable route for advancing weak NIR detection.