Beyond 800 nm: recent progress in high-performance near-infrared thermally activated delayed fluorescence based OLEDs

Near-infrared (NIR) thermally activated delayed fluorescence (TADF) materials with emission peaks beyond 800 nm have attracted considerable attention owing to their potential applications in bioimaging, optical communication, and night-vision technologies. However, their development remains limited by the energy gap law, which leads to severe non-radiative decay and low external quantum efficiencies. In recent years, researchers have broken through these bottlenecks by employing various molecular design strategies, such as modulating charge-transfer characteristics and reducing the singlet-triplet energy splitting. These efforts have enabled the realization of efficient TADF emission extending into the deep-NIR region. In this review, we summarize recent advances in NIR-TADF emitters with emission maxima beyond 800 nm, focusing on their molecular design principles, photophysical properties, and device performance, and discuss future perspectives for achieving high-efficiency deep-NIR OLEDs.