Near-Infrared (NIR) Organic Light-Emitting Diodes (OLEDs): Challenges and Opportunities

The rapid development of the science and technology of organic semiconductors has already led to mass application of organic light-emitting diodes (OLEDs) in television monitors of outstanding quality as well as in a large variety of smaller displays found in smartphones, tablets, and other gadgets, while introduction of the technology to the illumination sector is imminent. Notably, the requirements of all such applications for emission in the visible range of the electromagnetic spectrum are well tuned to the optical and electronic properties of typical organic semiconductors, thereby representing relatively "low-hanging fruits," in terms of material development and exploitation. However, the question arises as to whether developing materials suited for efficient near-infrared (NIR, 700-1000 nm) emission is possible, and, crucially, desirable to enable new classes of applications spanning from through-space, short-range communications to biomedical sensors, night vision, and more generally security applications to name but a few. Here, the major fundamental hurdles to be overcome to achieve efficient NIR emission from organic pi-conjugated systems are discussed, recent progress is reviewed, and an outlook for further development of both materials and applications is provided.