Robust Luminescent Materials with Prominent Aggregation-Induced Emission and Thermally Activated Delayed Fluorescence for High-Performance Organic Light-Emitting Diodes

Abstract

Aggregation-induced emission (AIE) materials have excellent solid-state emission by suppressing concentration quenching and exciton annihilation, while thermally activated delayed fluorescence (TADF) materials are able to fully utilize electrogenerated singlet and triplet excitons. The collaboration of AIE and TADF should be a rational strategy to design novel robust luminescent materials. Herein, two new materials with both prominent AIE and TADF properties are developed based on a central benzoyl acceptor core and different donor units. Their crystal and electronic structures, thermal stabilities, photophysical properties, and energy levels are investigated systematically. The doped organic light-emitting diodes (OLEDs) based on them show green lights and perform outstandingly, providing excellent electroluminescence (EL) efficiencies of up to 19.2%, 60.6 cd A^-1, and 59.2 lm W^-1. Their nondoped OLEDs are turned on at very low turn-on voltages (2.7 V) and afford yellow lights and high EL efficiencies of 9.7%, 26.5 cd A^-1, and 29.1 lm W^-1, with low efficiency roll-off. These results actually demonstrate the feasibility to explore new efficient emitters by the marriage of AIE and TADF.