Novel benzonitrile-based AIE host with high triplet energy for highly efficient solution-processed blue TADF OLEDs

Abstract

Developing high-performance host materials for blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) is an effective way to improve emission efficiency through overcoming intermolecular interactions. In this work, three novel AIE-active materials with twisted donor-acceptor structures (3phCN-Cz, 3phCN-ICz and 3phCN-tCzICz) are designed and synthesized by modifying the donor unit. Encouragingly, all the molecules exhibited high triplet energies (>2.80 eV) to prevent exciton returning and aggregation‐induced emission (AIE) property for suppressing exciton quenching. Furthermore, systematic studies demonstrated that 3phCN-ICz and 3phCN-tCzICz with larger steric resistance units can not only possess good thermal and electrochemical stability but also exhibit excellent inhibition ability of intermolecular interactions, which are suitable for constructing high-efficiency solution-processed blue TADF devices. Ultimately, the 4TCzBN was employed as the blue TADF emitter, and the solution-processed OLEDs based on 3phCN-ICz achieved the maximum external quantum efficiency (EQEmax), the maximum current efficiency (CEmax), and the lowest turn-on voltage of 22.04%, 41.88 cd A−1, and 3.5 V, respectively. This work demonstrates the potential application of AIE materials with high triplet energy for solution-processed blue TADF OLEDs.