A new multifunctional fluorenyl carbazole hybrid for high performance deep blue fluorescence, orange phosphorescent host and fluorescence/phosphorescence white OLEDs

A new multifunctional host material, 3,3′-(2,7-di(quinolin-8-yl)-9H-fluorene-9,9-diyl)bis(9-phenyl-9H-carbazole) has been designed, synthesized and used in high performance OLEDs. This tetrasubstituted fluorene was found to have good morphological and thermal stability with a high glass transition temperature of 192 °C and a decomposition temperature of 480 °C. A non-doped tri-layer blue fluorescent device based on this tetrasubstituted fluorene shows a deep blue emission with a Commission Internationale de L’Eclairage coordinates of (0.16, 0.10) and a maximum power efficiency of 1.1 lm/W. An orange phosphorescent device using this tetrasubstituted fluorene as a host in conjunction with an iridium complex as dopant exhibits a maximum power efficiency of 21.0 lm/W, which is much higher than that of a biscarbazolylbiphenyl-based control device (11.5 lm/W) with the same device structure. Furthermore, by using the tetrasubstituted fluorene as a blue florescent emitter and a host for phosphorescent dopant, a white emitting OLED with a maximum power efficiency of 22.5 lm/W and CIE coordinates of (0.38, 0.33) were obtained. These results show that this tetrasubstituted fluorene is a versatile multifunctional material for OLED applications.

► The tetrasubstituted fluorene was found to have good thermal stability.
► A deep blue fluorescent device shows a power efficiency of 1.1 lm/W.
►  An orange device using DFBC as a host exhibits a maximum power efficiency of 21.0 lm/W.
► The efficiency is higher than that of a biscarbazolylbiphenyl-based device with the same structure.
► A white OLED with a maximum power efficiency of 22.5 lm/W was obtained.