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

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.