Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via...

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 (ΔE_st), 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.