Laboratory for Computational and Theoretical Chemistry of Advanced Materials, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia.
Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
Adv Mater. 2017 Dec;29(46). doi: 10.1002/adma.201702767. Epub 2017 Oct 17.
In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔE ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔE with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.
在由电子给体和电子受体部分组成的热激活延迟荧光 (TADF) 发射器的传统分子设计中，在强烈扭曲的结构中实现小的单重态-三重态能量间隙 (ΔE) 通常会转化为小的荧光振子强度，这会显著降低发射量子产率并限制有机发光二极管器件中的效率。在这里，基于咔唑给体和 2,4,6-三苯基-1,3,5-三嗪受体部分组成的 TADF 发射器的量子化学计算结果，提出了一种新的策略，用于设计具有小 ΔE 和大荧光振子强度的高效 TADF 发射器。由于这种策略超出了结构扭曲、电荷转移型发射器的传统框架，重要的是，它为平面分子成为高效 TADF 发射器开辟了道路。在这里，理论上设计了由吖啶并三嗪和二苯并三嗪部分组成的新型发射器，由于分子内氢键相互作用，它是共面的。这种六甲基吖啶并三嗪-三嗪 (HMAT-TRZ) 发射器的合成及其初步光物理特性表明 HMAT-TRZ 是一种潜在的高效 TADF 发射器。
