New Bipolar Host Materials for Realizing Blue Phosphorescent Organic Light-Emitting Diodes with High Efficiency at 1000 cd/m2
Author(s):
Min Ju Cho, Sun Jae Kim, Seung Hee Yoon, Jicheol Shin, Tae Ryang Hong, Hyung Jong Kim, Young Hoon Son, Ju Sik Kang, Hyun Ah Um, Tae Wan Lee, Jong-Kwan Bin, Bang Sook Lee, Joong Hwan Yang, Gee Sung Chae, Jang Hyuk Kwon, Dong Hoon Choi
Journal:
ACS Applied Materials & Interfaces
Year:
2014
Volume:
6
Pages
19808–19815
DOI:
10.1021/am505049h
Abstract:
New host molecules such as 9-(6-(9H-carbazol9-yl)pyridin-3-yl)-6-(9H-carbazol-9-yl)-9H-pyrido[2,3-b]-
indole (pPCB2CZ) and 9-(6-(9H-carbazol-9-yl)pyridin-2-yl)-
6-(9H-carbazol-9-yl)-9H-pyrido[2,3-b]indole (mPCB2CZ)
were designed and synthesized for blue phosphorescent
organic light-emitting diodes (PhOLEDs). The glass transition
temperatures of two host molecules were measured higher
than 120 °C, and the identical triplet energies were determined
to be 2.92 eV for both molecules. The bis(3,5-difluoro-2-(2-
pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic)-doped
mPCB2CZ-based PhOLED exhibited practically useful driving
voltage of 4.8 V in a simple organic three layer device
configuration which has a smaller number of interfaces in conventional multilayer PhOLEDs. Also, the high quantum efficiency
of 23.7% is reported at the practically useful brightness value of 1000 cd/m2.