Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via Introducing Intramolecular Hydrogen-Bonding Interactions for Efficient Solution-Processed Nondoped OLEDs

Purely organic luminescent materials concurrently exhibiting
thermally
activated delayed fluorescence (TADF) and aggregation-induced emission
(AIE) features are in great demand due to their high efficiency in
aggregation-state toward efficient nondoped OLEDs. Herein, a class
of TADF emitters adopting phenyl­(pyridyl)­methanone as electron-accepting
segments and di­(tert-butyl)­carbazole and 9,9-dimethyl-9,10-dihydroacridine
(or phenoxazine) as electron-donating groups are designed and synthesized.
The existence of intramolecular hydrogen bonding is conducive to minish
the energy difference between a singlet and a triplet (ΔEst), suppress nonradiative decay, and increase
the luminescence efficiency. By using 3CPyM-DMAC as the emitter, the
nondoped device via a solution process realize a high current efficiency
(CE) and external quantum efficiency (EQE) of 35.4 cd A–1 and 11.4%, respectively, which is superior to that of CBM-DMAC with
a CE and EQE of 14.3 cd A–1 and 6.7%. This work
demonstrates a promising tactic to the establishment of TADF emitters
with AIE features via introducing intramolecular hydrogen bonding.