3,3'-Bicarbazole-Based Host Molecules for Solution-Processed Phosphorescent OLEDs.

Solution-processed organic light-emitting diodes (OLEDs) are attractive due to their low-cost, large area displays, and lighting features. Small molecules as well as polymers can be used as host materials within the solution-processed emitting layer. Herein, we report two 3,3'-bicarbazole-based host small molecules, which possess a structural isomer relationship. 9,9'-Di-4-n-butylphenyl-9,9'-3,3'-bicarbazole () and 9,9'-di-4-t-butylphenyl-9,9'-3,3'-bicarbazole () exhibited similar optical properties within solutions but different photoluminescence within films. A solution-processed green phosphorescent OLED with the host exhibited a high maximum current efficiency and power efficiency of 43.1 cd/A and 40.0 lm/W, respectively, compared to the device with the host.