High-Efficiency Blue Phosphorescence Organic Light-Emitting Diode with Ambipolar Carbazole鈥揟riazole Host
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- 作者：Tien-Lung Chiu ; Hsin-Jen Chen ; Yu-Hsuan Hsieh ; Jau-Jiun Huang ; Man-kit Leung
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：July 23, 2015
- 年：2015
- 卷：119
- 期：29
- 页码：16846-16852
- 全文大小：455K
- ISSN：1932-7455
文摘
An ambipolar material with a high triplet energy of 3.1 eV, 9-(2-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl)-9H-carbazole (CbzTAZ), was synthesized by conjugating an electron-transporting 1,2,4-triazole and a hole-transporting carbazole and employed as the host doping with blue emitter iridium(III)bis[4,6-(difluorophenyl)-pyridinato-N,C2鈥瞉picolinate (FIrpic) to be the emitting layer (EML) of an efficient blue phosphorescent organic light-emitting diode (PhOLED). By adjusting the ratio between CbzTAZ and FIrpic, an efficient OLED performance with a current efficiency (畏C) of 50 cd/A and an external quantum efficiency (畏EQE) of 23.8% can be obtained. The position of the recombination zone located inside the EML close to the electron-transporting layer (ETL) can be detected by partially doping FIrpic in one of the three EML regions. By fine-tuning the thickness of the ETL to balance electrons and holes in the EML, a highly efficient blue PhOLED with a maximum 畏C of 52.1 cd/A, a maximum power efficiency of 46.1 lm/W, and a maximum 畏EQE of 24.4% was obtained. In addition, the device demonstrated a favorable efficiency roll-off (畏C of 44.6 cd/A and 畏EQE of 21%) at a high brightness of 1000 cd/m2.