New hole blocking material for green-emitting phosphorescent organic electroluminescent devices

The new amorphous molecular material, 2,5-bis(4-triphenylsilanyl-phenyl)-[1,3,4]oxadiazole, that functions as good hole blocker as well as electron transporting layer in the phosphorescent devices. The obtained material forms homogeneous and stable amorphous film. The new synthesized showed the reversible cathodic reduction for hole blocking material and the low reduction potential for electron transporting material in organic electroluminescent (EL) devices. The fabricated devices exhibited high performance with high current efficiency and power efficiency of 45 cd/A and 17.7 lm/W in 10 mA/cm2, which is superior to the result of the device using BAlq (current efficiency: 31.5 cd/A and power efficiency: 13.5 lm/W in 10 mA/cm2) as well-known hole blocker. The ITO/DNTPD/α-NPD/6% Ir(ppy)3 doped CBP/2,5-bis(4-triphenylsilanyl-phenyl)-[1,3,4]oxadiazole as both hole blocking and electron transporting layer/Al device showed efficiency of 45 cd/A and maximum brightness of 3000 cd/m2 in 10 mA/cm2.