9,9′-bis(2,2-diphenylvinyl)[3,3′]bicarbazole as low cost efficient hole transporting material for application in red PhOLEDs

Low-cost bicarbazole-based hole transporting derivative with diphenylvinyl substitutions was synthesized by simple procedure and characterized. The respective glass transition temperature of the material was estimated to be 81 °C, which can provide morphologically-stable amorphous films for applications in organic light emitting diodes. The compound possesses an adequate ionization potential, suitable triplet energy and high hole drift mobility of 5.54 eV, 2,61 eV and of 2 × 10−3 cm2/V·s, respectively, which make it a suitable hole transporting material for use in red phosphorescent organic light-emitting diodes. The respective peak efficiency of the red device with the p-type dopant was recorded at 8.3% (5.2 cd/A and 3.3 lm/W) and at 7.8% (4.9 cd/A and 1.9 lm/W) for 100 cd/m [2] brightness, demonstrating high potential of the material for applications in light emitting diodes. The characteristics indicated that device with the bicarbazole-based compound exhibited better performance than those of widely used 1,1-bis [(di-4-tolylamino)phenyl]cyclohexane (TAPC) -based device.