Highly Efficient Sensitized Chiral Hybridized Local and Charge‐Transfer Emitter Circularly Polarized Electroluminescence

This work describes the first hot exciton fluorescent material based on benzo[c][1,2,5]thiadiazole and chiral binaphthol enabling circularly polarized luminescence (CPL) through a chiral perturbation strategy. The new molecular architecture displays CPL, hybridized local and charge transfer (HLCT) properties concurrently. Utilizing it as the emitter, circularly polarized organic light-emitting diodes (CP-OLEDs) achieve an external quantum efficiency (EQE) of 7.2% with a good exciton utilization (36%) and a moderate circularly polarized electroluminescence (CPEL) dissymmetry factor (g(EL), 2.1 x 10(-3)). In addition, the CP-HLCT molecule is sensitized by a thermally activated delayed fluorescence material, significantly ameliorating the efficiency of HLCT fluorescent CP-OLEDs. Excellent performances of twofold maximum EQE (EQE(max)) of 15.3% and 82% exciton utilization are obtained in the sensitized device, regarding an extremely low-efficiency roll-off of 2.6% at 1000 cd m(-2) as well as CPEL with a g(EL) value of 2.0 x 10(-3).