“Exciton Recovery” Strategy in Hot Exciton Emitter toward High-Performance Non-Doped Deep-Blue and Host-Sensitized Organic Light-Emitting Diodes |
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Authors: | Baoxi Li Jingli Lou Han Zhang Ganggang Li Xin He Yu Huang Nan Zheng Zhiming Wang Dongge Ma Ben Zhong Tang |
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Affiliation: | AIE Institute, State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, Center for Aggregation-Induced Emission, South China University of Technology (SCUT), Guangzhou, 510640 P. R. China |
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Abstract: | The “hot exciton” mechanism based on high-lying reverse intersystem crossing process has great advantages in achieving high-performance deep-blue organic light-emitting diodes (OLEDs). Nevertheless, how to solve the loss of high-lying excitons to improve device performance further is a pressing and challenging issue. To break through this shackle, a novel deep-blue emitter based on “exciton recovery” strategy is successfully design, namely CAT. By combining the transient absorption spectrum, theoretical calculation, magneto-electroluminescence, and transient-electroluminescence measurements, the multi-channeled pathways of excitons utilization via hot exciton and triplet-triplet annihilation processes is comprehensively demonstrated, and the proportion of singlet excitons by each channel. Finally, a high exciton utilization efficiency is successfully achieved, and the non-doped OLED based on CAT exhibit an excellent external quantum efficiency of 10.39% with the CIE coordinates of (0.15, 0.087). Furthermore, the sensitized blue fluorescent OLED by CAT as host also achieves excellent performance. More importantly, the operational lifetime of the “multi-channel” sensitized device is evaluated for the first time, performing the remarkable LT50 (lifetime to 50% of the initial luminance) of 320 h at 540 cd m?2. These results fully reveal the significance of the “exciton recovery” strategy and give new inspiration for exploring high-performance blue OLEDs. |
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Keywords: | exciton recovery high-performance organic light-emitting diodes hot excitons multi-channels triplet-triplet annihilation |
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