Ternary Compensation Enables High‐sensitive Efficient Upconversion Device for NIR Visualization

Abstract Beyond the crystalline photodiodes for infrared visualization, with the limitation of opacity and complex lithographic processes, organic upconversion device (UCD) have emerged as a potential alternative. In this research, a ternary compensation strategy is implemented in a non‐fullerene‐based active layer to reduce the dark current of the detector and enhance its detection performance, which enables high‐sensitive efficient upconversion device for near‐infrared light (NIR) visualization. The device achieves an infrared‐to‐visible upconversion efficiency of 16.68% when resolving the 980 nm infrared signal at a power density of 0.4 mW cm −2 . In addition, by replacing the semitransparent matrix electrodes, a large‐area (12.25 cm 2 ) is further fabricated, lightweight (6.5 g containing encapsulation), pixel‐less (equivalent resolution 1270 ppi), and semitransparent (AVT ≈40%) UCD with microsecond response time. The fabricated UCD is demonstrated in pixel‐less active infrared naked‐eye visualization and infrared counter‐surveillance, fostering the advancement of infrared visualization technology.