9,9'-Bicarbazole: New Molecular Skeleton for Organic Light-Emitting Diodes

Carbazole is a classic tricyclic aromatic compound that has been widely used in organic optoelectronics. Appropriate functionalization on its aromatic rings will significantly increase the possibilities for its application as an optoelectronic material. Position engineering of carbazole not only leads to its structural diversity, but also substantially enriches its functionality. Bicarbazoles have 15 isomers, most of which are well studied and have been applied in organic light-emitting diodes (OLEDs). However, one isomer, 9,9'-bicarbazole, is rarely investigated as an OLED material. Therefore, two 9,9'-bicarbazole derivatives, 3,3'-di(10H-phenoxazin-10-yl)-9,9'-bicarbazole and 3,3'-di(10H-phenothiazin-10-yl)-9,9'-bicarbazole, have been designed and prepared for use as host materials for green and red OLEDs. These two compounds demonstrated good device performances, and it is believed that the 9,9'-bicarbazole building block could be a novel platform for the design of efficient host materials for OLEDs.