Aggregation‐induced emission (AIE) and hybridized local and charge‐transfer (HLCT) materials are two kinds of promising electroluminescence systems for the fabrication of high‐efficiency organic light‐emitting diodes (OLEDs) by harnessing “hot excitons” at the high‐lying triplet exciton states (Tn, n ≥ 2). Nonetheless, the efficiency of the resulting OLEDs did not meet expectations due to the possible loss of Tn→Tn−1. Herein, experimental results and theoretical calculations demonstrate the “hot exciton” process between the high‐lying triplet state T3 and the lowest excited singlet state S1 in an AIE material 4⁗‐(diphenylamino)‐2″,5″‐diphenyl‐[1,1″:4′,1″:4″,1′″:4′″,1⁗‐quinquephenyl]‐4‐carbonitrile (TPB‐PAPC) and it is found that the Förster resonance energy transfer (FRET) between two molecules can facilitate the “hot exciton” process and inhibit the T3→T2 loss by doping a blue fluorescent emitter in TPB‐PAPC. Finally, the doped TPB‐PAPC blue OLEDs achieve a maximum external quantum efficiency (EQEmax) of 9.0% with a small efficiency roll‐off. Furthermore, doping the blue fluorescent emitter in a HLCT material 2‐(4‐(10‐(3‐(9H‐carbazol‐9‐yl)phenyl)anthracen‐9‐yl)phenyl)‐1‐phenyl‐1H‐phenanthro[9,10‐d] imidazole (PAC) is used as the emission layer, and the resulting blue OLEDs exhibit an EQEmax of 17.4%, realizing the efficiency breakthrough of blue fluorescence OLEDs. This work establishes a physical insight in the design of high‐performance “hot exciton” molecules and the fabrication of high‐performance blue fluorescence OLEDs.

Aggregation-induced emission (AIE) materials are attractive for the fabrication of high efficiency organic light-emitting diodes (OLEDs) by harnessing “hot excitons” from high-lying triplet exciton states (Tn, n>2) and high photoluminescence...

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Current-dependent MEL and MC experimental curves of Dev. 1 at room temperature and 100 K and at 100 μA; temperature-dependent MEL curves of device 3 at 100 μA; rubrene and DCJTB concentration-dependent MEL experimental curves of Dev. 1; and schematic diagram of spin-pair states in Dev. 1 with a high DCJTB doping concentration (PDF)■ AUTHOR INFORMATION

Magneto-electroluminescence was used to observe reverse intersystem crossing in exciplex-based organic light-emitting diodes directly.