The synthesis of stable blue TADF emitters and the corresponding matrix materials is one of the biggest challenges in the development of novel OLED materials. We present six bipolar host materials based on triazine as an acceptor and two types of donors, namely, carbazole, and acridine. Using a tool box approach, the chemical structure of the materials is changed in a systematic way. Both the carbazole and acridine donor are connected to the triazine acceptor via a para- or a meta-linked phenyl ring or are linked directly to each other. The photophysics of the materials has been investigated in detail by absorption-, fluorescence-, and phosphorescence spectroscopy in solution. In addition, a number of DFT calculations have been made which result in a deeper understanding of the photophysics. The presence of a phenyl bridge between donor and acceptor cores leads to a considerable decrease of the triplet energy due to extension of the overlap electron and hole orbitals over the triazine-phenyl core of the molecule. This decrease is more pronounced for the para-phenylene than for the meta-phenylene linker. Only direct connection of the donor group to the triazine core provides a high energy of the triplet state of 2.97 eV for the carbazole derivative CTRZ and 3.07 eV for the acridine ATRZ. This is a major requirement for the use of the materials as a host for blue TADF emitters.

稳定的蓝色TADF发射体和相应基质材料的合成是新型OLED材料开发中的最大挑战之一。我们提出了六种基于三嗪作为受体和两种类型的供体（即咔唑和吖啶）的双极性主体材料。使用工具箱方法，以系统的方式改变材料的化学结构。咔唑和吖啶供体均通过对位或间位连接的苯环连接至三嗪受体或直接彼此连接。通过溶液中的吸收光谱、荧光光谱和磷光光谱详细研究了材料的光物理学。此外，还进行了许多 DFT 计算，使人们对光物理学有更深入的了解。由于重叠电子和空穴轨道在分子的三嗪-苯基核心上的延伸，供体和受体核心之间苯基桥的存在导致三线态能量显着降低。这种减少对于对亚苯基比对于间亚苯基连接体更明显。只有供体基团与三嗪核心直接连接才能为咔唑衍生物提供 2.97 eV 的三重态高能CTRZ吖啶为 3.07 eVATRZ。这是使用该材料作为蓝色 TADF 发射体主体的主要要求。