Stabilizing negative charge in organic molecules for high-efficiency, long-lifetime delayed electroluminescence

Abstract The internal quantum efficiencies of organic light-emitting diodes (OLEDs) with thermally activated delayed fluorescence (TADF) have reached 100%. However, the combination of a high efficiency and a long operational lifetime is still a major conundrum of commercialization. Here, we develop TADF emitters with auxiliary acceptors to stabilize negative charge by delocalizing electron distribution, not only strengthening the intrinsic molecular stability in both excited and anionic states, but also leading to faster exciton consumption by balancing triplet-up-conversion and singlet-radiation. The targeted compounds as emitters in OLEDs exhibited high maximum external quantum efficiencies of 27.9-37.1% and remarkably long LT95s (times to 95% of the initial luminance) of 446 and 628 h for blue and greenish-blue devices at 1,000 cd m-2, which can be further extended to 451 and 2,491 h by using them as sensitizers for blue and green multi-resonance (MR) emitters with y color coordinates of 0.27 and 0.71, respectively.