49‐2: Highly Efficient and Stable Narrow‐Band MR‐TADF Emitter for Top‐Emission Red OLED Approaching B.T.2020

We reported two narrowband red MR‐TADF emitters KHU‐RD‐01 and KHU‐RD‐02 by introducing five‐membered heterocyclic scaffolds. These emitters exhibited red emission at 613 nm with narrow band FWHM of 32 nm. The fabricated BE‐OLED exhibited high EQE max of 22% with long lifetime of LT95 2039 h @ 1000 cd/m 2 and further to improve the color purity, we optimized TE‐OLED with KHU‐RD‐02 results in high current efficiency of 41.26 cd/A with CIE (x, y) = (0.68, 0.32) approaching near to B.T.2020.