Highly Efficient Sensitized Chiral Hybridized Local and Charge-Transfer Emitter Circularly Polarized Electroluminescence
Fan-Cheng Kong1,#, Sheng-Yi Yang1,#, Xiang-Ji Liao2,#, Zi-Qi Feng1, Wan-Shan Shen1, Zuo-Quan Jiang1, Dong-Ying Zhou1,3,*, You-Xuan Zheng2,*, and Liang-Sheng Liao1,4,*
1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China.
2State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
3College of Energy, Soochow Institute for Energy and Materials Innovations (SIEMIS), Soochow University, Suzhou, Jiangsu 215006, China
4Macau Institute of Materials Science and Engineering, Macau University of Science and Technology, Macao, 999078, China.
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 (gEL, 2.1 × 10−3). In addition, the CP-HLCT molecule is sensitized by a thermally activated delayed fluorescence (TADF) material, significantly ameliorating the efficiency of HLCT fluorescent CP-OLEDs. Excellent performances of twofold maximum EQE (EQEmax) 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 gEL value of 2.0 × 10−3.