Synthesis and device properties of carbazole/benzimidazole-based host materials

We report two bipolar host materials bearing hole-transport benzofurocarbazole/indenocarbazole cores and an electron-transport benzimidazole moiety for red phosphorescence organic light emitting devices (PhOLEDs). The two novel host materials exhibited excellent physical properties with high thermal stabilities, appropriate HOMO-LUMO energy levels and balanced charge transport. Both of them were applied to fabricate red PhOLEDs as promising host materials, and 7,7-dimethy1-5-(4'-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1'-biphenyl]-4-yl)-5,7-dihydroindeno[2,1-b]carbazole (ICBI) based device demonstrated outstanding electroluminescence performance with the maximum current efficiency, power efficiency and external quantum efficiency of 33.0 cd/A, 13.91m/W and 18.9%, respectively. (C) 2017 Elsevier Ltd. All rights reserved.