Here, we designed and synthesized three donor-acceptor (D-A) emitters, 1-phenyl-2-(4-(2-phenyl-[1], [2], [4]triazolo[1,5-a]pyridin-6-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (m-PPI-TP), 1-phenyl-2-(4-(2-phenyl-[1], [2], [4]triazolo[1,5-a]pyridin-7-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (p-PPI-TP) and 1-phenyl-2-(4-(2-phenyl-[1], [2], [4]triazolo[1,5-a]pyridin-8-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (o'-PPI-TP), based on [1], [2], [4]triazolo[1,5-a]pyridine (TP) as electron-transporting unit and 1,2-diphenyl-1H-phenanthro[9,10-d]imidazole (PPI) as hole-transporting moiety serving as emitting block concurrently. All three compounds were demonstrated to be thermally stable with decomposition temperatures (T_d) in the range of 454-476 °C and high photoluminescence quantum yields over 86%. Besides, high exciton utilization efficiency (EUE) via “hot exciton” process was proved according to photophysical experiments and theoretical calculations analysis. What’s more, the structure-property relationships between different substituted sites of the TP building block and PPI unit were also unveiled. Finally, the non-doped blue and doped deep-blue OLEDs were fabricated with high external quantum efficiency (EQE) approaching 8%. The yellow and red phosphorescent OLEDs (PHOLEDs) based on m-PPI-TP as the host material achieved the best EL performance with EQE of 26.55% and 20.35%, respectively.

在这里，我们设计并合成了三种供体-受体（DA）发射体，1-phenyl-2-(4-(2-phenyl-[1], [2], [4]triazolo[1,5- a ]pyridin- 6-基)苯基)-1 H-菲[9,10- d ]咪唑( m-PPI-TP) , 1-苯基-2-(4-(2-苯基-[1], [2], [ 4] triazolo[ 1,5- a ]pyridin-7-yl)phenyl)-1 H- phenanthro[9,10- d ]imidazole ( p-PPI-TP) and 1-phenyl-2-(4-(2 ) -苯基-[1]、[2]、[4]三唑并[1,5 - a ]吡啶-8-基)苯基)-1 H-菲[9,10- d ]咪唑( o'-PPI-TP ) , 基于 [1], [2], [4]triazolo[1,5- a]吡啶（TP）作为电子传输单元和1,2-二苯基-1 H-菲并[9,10 - d ]咪唑（PPI）作为空穴传输部分同时用作发光块。所有三种化合物都被证明在分解温度下是热稳定的 ( T _d) 在 454-476 °C 范围内和超过 86% 的高光致发光量子产率。此外，通过光物理实验和理论计算分析，证明了“热激子”过程具有较高的激子利用效率（EUE）。此外，还揭示了TP构建块和PPI单元的不同取代位点之间的结构-性质关系。最后，以接近 8% 的高外部量子效率 (EQE) 制造了非掺杂蓝色和掺杂深蓝色 OLED。以m-PPI-TP为主体材料的黄色和红色磷光OLED（PHOLED）实现了最佳的EL性能，EQE分别为26.55%和20.35%。