High‐Performance Solution‐Processable Organic Light‐Emitting Diode Based on a Narrowband Near‐Ultraviolet and a Hot Exciton Strategy

Abstract Achieving high efficiency narrowband near‐ultraviolet (NUV) emitters in organic light emitting diode (OLED) is still a formidable challenge. Herein, a proof‐of‐concept hybridized local and charge transfer (HLCT) molecule, named ICz‐BO, is prepared and characterized, in which both multiresonant (MR) skeletons are integrated via conjugation connection. A slightly distorted structure and weak intramolecular charge transfer (CT) interaction between two MR subunits lead to a high‐lying reverse intersystem crossing (h‐RISC) channel of T 6 → S 1 , also evidenced by both experimental and calculated results. Impressively, the ICz‐BO emitter exhibits outstanding narrowband NUV emission at 404 nm with a full‐width at half maximum of 28 nm in toluene solution. The solution processable OLED shows an excellent device performance with the recorded maximum external quantum efficiency of 12.01 %, concomitant with an extremely low y‐axis Commission Internationale de l’Éclairage (CIE y ) value of 0.031. To the best of our knowledge, this is the highest efficiency reported for the HLCT‐based NUV‐OLEDs to date. This research proves that the MR skeleton plays a positive effect on the narrowband hot exciton emitter, which provides an alternative paradigm for developing high‐efficiency NUV emitters.