High‐Performance Solution‐Processable Organic Light‐Emitting Diode Based on a Narrowband Near‐Ultraviolet Emitter 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 T6→S1, 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 (CIEy) 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.