Abstract
We report on the synthesis and electroluminescence characteristics of a new green-emitting material, 3,7-bis(1-(biphenyl-4-yl)benzimidazol-2-yl)10-methylphenothiazine (PhBBMP) containing the electron-donating phenothiazine core and the electron-accepting biphenyl benzimidazole substituent. An optimized OLED device with the structure of [ITO/NPB (40 nm)/PhBBMP (30 nm)/BCP (10 nm)/TPBI (30 nm)/LiF (1 nm)/Al (100 nm)] exhibited a luminous efficiency of 4.5 cd/A and an external quantum efficiency of 0.9% at 100 mA/cm2, and the maximum luminance of 12,000 cd/m2 with the CIE 1931 chromaticity coordinates of (0.21, 0.54). A more balanced charge carrier injection and the charge confinement in the emitting layer cooperatively contributed to improve the performance of the device prepared with the PhBBMP emitting layer.
Acknowledgement
This research was supported by Basic Science Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (Grant No. 2009-0090177), and the “GRRC” Project of Gyeonggi Provincial Government, ROK.