Synthesis of Bicarbazole-based Ambipolar Hosts and Application in Organic Light-emitting Devices

doi:10.7517/j.issn.1674-0475.2014.02.141

Abstract

Abstract:

Carbazole derivatives are usually used as hole transport and host materials because of their good hole transport ability and high triplet energy. In this paper, a novel bicarbazole derivative, named BCzDCN, was designed and synthesized by incorporating electron-withdrawing cyano group into bicarbazole at 3,6 position. Its thermal, photophysical and electrochemical properties were systematically investigated. The triplet energy of BCzDCN is higher than that of the most popular blue phosphorescent material iridium(Ⅲ) bis[(4,6-difluorophenyl)pyridinato-N,C²']picolinate (FIrpic). Therefore BCzDCN could be used as host material for blue phosphorescent organic light-emitting diodes (PHOLEDs) and further for white PHOLEDs. Blue and White PHOLEDs using BCzDCN as host exhibited excellent performance with maximum current efficiencies of 34.6 cd/A and 59.0 cd/A, respectively. Meanwhile, both the blue and white PHOLEDs exhibited extraordinary low efficiency roll-offs, their efficiencies roll-offs were merely 4.1% and 5.1% at the brightness of 1000 cd/m², respectively.

Key words: electroluminescence, phosphorescence, host material, carbazole, cyano group

CUI Linsong, LIU Yuan, JIANG Zuoquan, LIAO Liangsheng. Synthesis of Bicarbazole-based Ambipolar Hosts and Application in Organic Light-emitting Devices[J]. Imaging Science and Photochemistry, 2014, 32(2): 141-149.

References

[1] 陈金鑫, 黄孝文. OLED有机电致发光材料与器件[M]. 北京:清华大学出版社, 2007, 1-34. Chen J X, Huang X W. Organic Electroluminescent Materials & devices[M]. Beijing: Tsinghua University Press, 2007, 1-34.
[2] 李子珅, 徐征, 赵谡玲, 等.照明用白光OLED的现状与挑战[J]. 现代显示, 2010, 7(114):17-25. Li Z K, Xu Z, Zhao S L, et al. Lighting technology conditions of white OLED with challenges[J]. Advance Display, 2010, 7(114):17-25.
[3] Kido J, Kimura M, Nagai K. Multilayer white light-emitting electroluminescent device[J]. Science, 1995, 267(5202): 1332-1134.
[4] 尹冬冬, 单璐, 沈玉全. 有机小分子电致发光研究进展[J]. 感光科学与光化学, 2000, 18(3): 235-242. Yin D D, Shan L, Shen Y Q. Recent advancements of the electroluminescence of organic small molecules[J]. Photographic Science and Photochemistry, 2000, 18(3): 235-242.
[5] Tang C W, Vanslyke S A. Organic electroluminescent diodes[J]. Applied Physics Letter, 1987, 51(12): 913-915.
[6] Baldo M A, Thompson M E, Forrest S R, et al. Highly efficient phosphorescent emission from organic electroluminescent devices[J]. Nature, 1998, 395: 151-154.
[7] Burrows P E, Thompson M E, Forrest S R, et al. Very high-efficiency green organic light-emitting devices based on electrophosphorescence[J]. Applied Physics Letter, 1999, 75(1): 4-6.
[8] Reineke S, LÜssem B, Leo, K, et al. White organic light-emitting diodes with fluorescent tube efficiency[J]. Nature, 2009, 459: 234-238.
[9] Kamtekar K T, Monkman A P, Bryce M R, et al. Recent advances in white organic light-emitting materials and devices (WOLEDs)[J]. Advance Materials, 2010, 22(5): 572-582.
[10] Tao Y, Yang C, Qin J. Organic host materials for phosphorescent organic light-emitting diodes[J]. Chemical Society Reviews, 2011, 40: 2943-2970.
[11] Chaskar A, Chen H F, Wong K T, et al. Bipolar host materials: a chemical approach for highly efficient electrophosphorescent devices[J]. Advance Materials, 2011, 23(34): 3876-3895.
[12] 郑才俊, 何鉴, 赵伟明, 等. 有机电致发光器件中的新型双极主体材料的合成及应用[J]. 感光科学与光化学, 2010, 28(6): 457-464. Zheng C J, He J, Zhao W M, et al. Synthesis and application of a new bipolar host for organic light-emitting devices[J]. Photographic Science and Photochemistry, 2010, 28(6): 457-464.
[13] Xiao L, Gong Q, Kido J, et al. Recent progresses on materials for electrophosphorescent organic light-emitting devices[J]. Advance Materials, 2011, 23(8): 926-952.
[14] Jeon S O, Yook K S, Lee J Y. Phenylcarbazole-based phosphine oxide host materials for high efficiency in deep blue phosphorescent organic light-emitting diodes[J]. Advance Functional Materials, 2009, 19(22): 3644-3649.
[15] 姜华, 刘云圻, 武霞, 等. 小分子配合物电致发光材料研究进展[J]. 感光科学与光化学, 2002, 20(2): 149-158. Jiang H, Liu Y Q, Wu X, et al. Research progress of low molecular weight complex electroluminescent materials[J]. Photographic Science and Photochemistry, 2002, 20(2): 149-158.
[16] Chou P T, Chi Y. Phosphorescent dyes for organic light-emitting diodes[J]. Chemistry-A European Journal, 2007, 13(2): 380-395.
[17] Su S J, Sasabe H, Kido J, et al. Highly efficient organic blue-and white-light-emitting devices having a carrier-and exciton-confining structure for reduced efficiency roll-off[J]. Advance Materials, 2008, 20(21): 4189-4194.
[18] Lee C, Lee J. Above 30% external quantum efficiency in blue phosphorescent organic light-emitting diodes using pyrido [2，3-b]indole derivatives as host materials[J]. Advance Materials, 2013, 25(38): 5450-5454.
[19] Tao Y, Qin J, Ma D, et al. Multifunctional triphenylamine/oxadiazole hybrid as host and exciton-blocking material: high efficiency green phosphorescent OLEDs using easily available and common materials[J]. Advance Functional Materials, 2010, 20(17): 2923-2929.