A Breakthrough in Solution-Processed Ultra-Deep-Blue HLCT-OLEDs: A Record External Quantum Efficiency Exceeding 10% based on Novel V-Shaped Emitters.

It has always been a great challenge to achieve high-efficiency solution-processed ultra-deep-blue organic light-emitting diodes (OLEDs) with the Commission Internationale de l'Eclairage (CIE) 1931 chromaticity coordinates matching the blue primary of Rec. ITU-R BT.2100, which specifies high dynamic range television (HDR-TV) image parameters. Inspired by hybrid local and charge transfer (HLCT) excited state emitters improving exciton utilization through high-lying reverse intersystem system crossing, a series of high-performance blue emitters by a V-shaped symmetric D-π-A-π-D design strategy are developed in this study. Here, the large torsions and unstable bonds of D-A structures could be improved through π bridges, and also the conjugation length and donor groups can be easily adjusted. The obtained emitters merit excellent photophysical and electrochemical properties, thermal stability, solution processibility, and HLCT excited state excellence. Results suggest that the OLEDs based on the obtained blue emitters all achieve high maximum external quantum efficiency (EQE max ) of more than 8% with very low efficiency roll-off. In particular, the device based on FIP-CZ exhibits a satisfactory ultra-deep-blue emission (CIE x,y = 0.1579, 0.0387) and a record-high EQE max (10.40%) among solution-processed HLCT-OLEDs, which is very close to the record EQE max of devices by vacuum vapor deposition technology. This article is protected by copyright. All rights reserved.