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 aggregationstate 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.

Strategies to enhance the ratio of the molecular horizontal emitting dipole orientation (Θ k ) for thermally activated delayed fluorescence (TADF) emitters have unlocked the full potential of efficiencies for the evaporated devices, which, however, remain elusive for the solution-processed ones. Here, a strategic molecular design for solution processable TADF emitters featuring high Θ k s is proposed by attaching flexible chains ended with bipolar 9,9'-spirobi[fluorene] subunits as anchoring groups onto TADF emitting core. It's unveiled that the anchoring groups not only enhance the horizontal orientation via enlarging molecular planarity, but also benefit the high photoluminescence in pristine films. The corresponding non-doped solution processable OLEDs substantiate an unprecedented maximum external quantum efficiency (EQE max ) > 30 %. Meanwhile, combining these compounds as TADF sensitizers, and multiple resonance final emitter, solution-processed OLEDs achieve an EQE max of 25.6 % with a narrow full width at half maximum of 29 nm.

Spatial separation of the TADF sensitizer and the fluorescent emitter improve the energy transfer efficiency by suppressing the energy loss and further enhance the electroluminescent performance.

Though the flourishment of materials with multiple resonance (MR) in blue to green regions, redemissive MR emitters are still rare in literatures, which definitely should be resolved for further applications. Herein, we report a simple molecular design strategy for the construction of pure-red MR emitters by conjugate charge transfer, which could greatly enhance the πconjugation degree and charge-transfer property of the target molecule while maintaining the basic feature of MR, leading to a significant redshift of more than 128 nm compared to the selected parent MR core. The proof-of-concept emitter PPZ-BN exhibited a pure-red emission with a dominant peak at 613 nm and a small full-width-at-half-maximum of 0.16 eV (48 nm). The optimized organic light-emitting diode showed a high external quantum efficiency of 26.9 %, a small efficiency roll-off, and an excellent operation stability (LT99) of more than 43 hours at an initial luminance of 10 000 cd m À 2 .