The electron-accepting [1,2,4]triazolo[1,5-a]pyridine (TP) moiety was introduced to build bipolar host materials for the first time, and two host materials based on this TP acceptor and carbazole donor, namely, 9,9′-(2-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (o-CzTP) and 9,9′-(5-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (m-CzTP), were designed and synthesized. These two TP-based host materials possess a high triplet energy (>2.9 eV) and appropriate highest occupied molecular orbital/lowest unoccupied molecular orbital levels as well as the bipolar transporting feature, which permits their applicability as universal host materials in multicolor phosphorescent organic light-emitting devices (PhOLEDs). Blue, green, and red PhOLEDs based on o-CzTP and m-CzTP with the same device configuration all show high efficiencies and low efficiency roll-off. The devices hosted by o-CzTP exhibit maximum external quantum efficiencies (η_ext) of 27.1, 25.0, and 15.8% for blue, green, and red light emitting, respectively, which are comparable with the best electroluminescene performance reported for FIrpic-based blue, Ir(ppy)₃-based green, and Ir(pq)₂(acac)-based red PhOLEDs equipped with a single-component host. The white PhOLEDs based on the o-CzTP host and three lumophors containing red, green, and blue emitting layers were fabricated with the same device structure, which exhibit a maximum current efficiency and η_c of 40.4 cd/A and 17.8%, respectively, with the color rendering index value of 75.

中文翻译：

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[1,2,4]三唑并[1,5- a ]吡啶作为高性能红色，绿色，蓝色和白色磷光有机发光器件通用主体材料的基石

首次引入电子接受性的[1,2,4]三唑并[1,5- a ]吡啶（TP）部分以构建双极性主体材料，并基于该TP受体和咔唑供体建立了两种主体材料，即，9,9'-（2-（[[1,2,4] triazolo [1,5 - a ]吡啶-2-基）-1,3-亚苯基）双（9 H-咔唑）（o -CzTP）和9,9'-（5-（[[1,2,4] triazolo [1,5 - a ]吡啶-2-基）-1,3-亚苯基）双（9 H-咔唑）（m-CzTP），进行了设计和合成。这两种基于TP的基质材料具有较高的三重态能量（> 2.9 eV）和适当的最高占据分子轨道/最低未占据分子轨道水平以及双极传输特征，这使其可作为通用基质材料应用于多色磷光有机光发射器件（PhOLED）。具有相同设备配置的基于o -CzTP和m -CzTP的蓝色，绿色和红色PhOLED均显示出高效率和低效率滚降。由主办的设备Ô（-CzTP表现出最大外部量子效率η _EXT）分别发出27.1％，25.0％和15.8％的蓝色，绿色和红色光，这与基于FIrpic的蓝色，Ir（ppy）₃的绿色和Ir（pq）的最佳电致发光性能相当_2个（基于acac）的红色PhOLED，配备有单组分主机。基于在白色PHOLED中ö -CzTP主机和含有红色，绿色，和蓝色的发光层的三个lumophors用相同的器件结构，其表现出的最大电流效率和η被制造_Ç分别40.4坎德拉/ A和17.8％，的，显色指数值为75。