New Amorphous Hole Blocking Materials for High Efficiency OLEDs

Two new amorphous molecular materials, 2,5-bis(2',5'-dimethyl-4-triphenylsilyl-phenyl)-[1,3,4]oxadiazole (BDTSO) and 2,5-bis(2',5'-dimethyl-4-triphenylsilyl-phenyl)-[1,3,4]thiadiazo1e (BDTST) were synthesized and investigated as hole blocking materials (HBM) for organic light-emitting diodes. The efficiency of electroluminescent device was improved by using BDTSO instead of BAlq. The current and power efficiency of the device using BDTSO as HBM is 39.6 cd/A and 13.1 lm/W at 10 mA/cm(2), respectively, which is higher compared to the same values for devices using BDTST and BAq which are typically used as HBM.