Orthogonally Substituted Benzimidazole-Carbazole Benzene As Universal Hosts for Phosphorescent Organic Light-Emitting Diodes

The
novel ambipolar hosts of o-CbzBz and o-DiCbzBz contain
carbazole and benzimidazole through an ortho-connection.
The orthogonal conformations cause the triplet state
to be confined at the carbazole units to secure efficient energy transfer.
The phosphorescent organic light-emitting diodes (PhOLEDs) show a
high current efficiency, power efficiency, and low efficiency roll-off. o-DiCbzBz can be used as a host
for sky-blue, green, and orange-red PhOLEDs, giving 57.5, 78.4, and
60.3 cd/A, respectively.

o-CbzBz与o-DiCbzBz这两种新型双极型主体材料，通过邻位连接方式结合了咔唑与苯并咪唑结构单元。其正交构象可使三重态局限于咔唑单元内，从而保障高效的能量传递过程。磷光有机发光二极管（phosphorescent organic light-emitting diodes，PhOLEDs）展现出优异的电流效率、功率效率以及极低的效率滚降现象。o-DiCbzBz可作为天蓝色、绿色及橙红色磷光有机发光二极管的主体材料，对应的器件性能分别可达57.5、78.4及60.3坎德拉每安培。