Two efficient fluorescence molecules, named 1-(4-trifluoromethylphenyl)-2-(4′-(1,4,5-triphenyl-1H-imidazole-2-yl)-[1,1′-biphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (PPI-PIM-1) and 1-(4-trifluoromethylphenyl)-2-(4′-(2,4,5-triphenyl-1H-imidazole-1-yl)-[1,1′-biphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (PPI-PIM-2) were designed and synthesized, in which the electron-withdrawing trifluoromethyl group was introduced firstly to N1-position benzene of phenanthroimidazole to improve the electron transporting ability and tune the charge transfer (CT) component. In addition, compared to biphenanthroimidazole derivatives, here, we break one rigid plane of phenanthroimidazole to inhibit aggregation-induced-quenching (ACQ) and change the position from C1 to N1 to restrict the conjugation length simultaneously. The devices based on PPI-PIM-1 and PPI-PIM-2 exhibited stable deep-blue emission with CIE coordinates of (0.15, 0.08) and (0.15, 0.07) and achieved maximum external quantum efficiencies of 4.3% and 4.5% respectively. More importantly, the corresponding exciton utilization efficiencies are as high as 27.0% and 30.3%.

两个有效的荧光分子，称为1-（4-三氟甲基苯基）-2-（4'-（1,4,5-三苯基-1H-咪唑-2-基）-[1,1'-联苯] -4-基）-1H-菲并[9,10- d ]咪唑（PPI-PIM-1）和1-（4-三氟甲基苯基）-2-（4'-（2,4,5-三苯基-1H-咪唑-1- yl）-[1,1'-联苯] -4-yl）-1H-菲[9,10- d ]咪唑（PPI-PIM-2设计和合成），其中首先将吸电子三氟甲基引入菲并咪唑的N1位苯中，以提高电子传输能力并调节电荷转移（CT）组分。此外，与联苯并咪唑衍生物相比，在这里，我们打破了苯并咪唑的一个刚性平面以抑制聚集诱导的猝灭（ACQ），并将位置从C1更改为N1以同时限制共轭长度。基于PPI-PIM-1和PPI-PIM-2的设备表现出稳定的深蓝色发射，CIE坐标为（0.15，0.08）和（0.15，0.07），最大外部量子效率分别为4.3％和4.5％。更重要的是，相应的激子利用效率分别高达27.0％和30.3％。