激基复合物体系因其具有较小的单/三线态能隙差（ΔEST）而成为热活化延迟荧光（TADF）材料的研究重点。然而，获得高发光效率和高辐射跃迁速率仍是激基复合物体系的难点。
近日，常州大学王亚飞教授、朱卫国教授和韩国成均馆大学Jun Yeob Lee教授等人在Science China Materials发表研究论文，设计合成了两种基于三(三唑)并三嗪单元的TADF材料TTT-HPh-Ac和TTT-MePh-Ac；并以这两种TADF材料为给体分子，以PO-T2T为受体分子，制备了两类激基复合物体系TTT-HPh-Ac:PO-T2T和TTTMePh-Ac:PO-T2T。
本文要点
1) 该材料体系具有极小的ΔEST值，快速的系统间反向交叉速率和非常高的发光效率（97%）。2) 以这类激基复合物为发光材料，其溶液加工型有机发光二极管获得了17.0%的最大外量子效率（EQEmax）；以激基复合物作为主体材料时，基于TTT-MePh-Ac:PO-T2T的溶液加工器件呈现出更好的性能，其EQEmax为20%，且在1000 cd m−2时的效率滚降非常小，仅为6%。本研究证明了同时具有分子内氢键和扭曲分子几何结构的分子更有利于提高激基复合物的发光效率，这为开发高效稳定的激基复合物体系提供了新的途径。Figure 1. (a) Schematic of proposed mechanism of exciplex-based OLED with D-A type fluorescent molecule and TADF type donor molecule; (b) schematics of the formation of exciplex by conventional donor molecules and the novel donor with intramolecular hydrogen bonding in this work.Figure 2. (a) Single-crystal structure of TTT-MePh-Ac; (b) the frontier molecular orbital distributions of TTT-MePh-Ac, TTT-HPh-Ac and exciplexes.Figure 3. (a) Schematic of the exciplex devices; (b) diagram of the mechanism of exciplex TTT-HPh-Ac:PO-T2T, TTT-MePh-Ac:PO-T2T (the mass ratio 85:15), and EL spectra; (c) AFM topographic images of TTT-MePh-Ac:PO-T2T. Standing in the air for 0 h (up); 48 h (down); the EQE-luminance curves of (d) TTT-HPh-Ac:PO-T2T and (e) TTT-MePh-Ac:PO-T2T.Figure 4. (a) Schematic diagram of the energy transfer mechanism in a high-efficiency exciplex BN5 device. (b) EQE and roll-off at different brightness levels of 3 wt% BN5, and 0.5 wt% TBRb. EQE of TTT-HPh-Ac:PO-T2T and TTT-MePh-Ac:PO-T2T as host. (c) The device of BN5 (3 wt%) and (d) the device of TBRb (0.5 wt%), with insets the EL spectra of the OLEDs.Xiaoyi Lai, Junqing Wang, Xiaolong Liu, Lei Hua, Bin Li, Weiguo Zhu, Jun Yeob Lee, Yafei Wang. Effective exciplex system with high emission efficiency via intramolecular hydrogen bonding for efficient solution processable OLEDs. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3067-x
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