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Twisted phenanthroimidazole based molecule with high triplet energy as host material for high efficiency phosphorescent OLEDs

Abstract

For host materials the high triplet energy level and bipolar charge transport ability are crucial the properties to achieve high performance phosphorescent organic light-emitting devices (OLEDs). A unique host material 2,2'-bis(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)biphenyl (BP-DPPI) was designed and synthesized by introducing two phenanthroimidazole groups onto the lateral o,o’-positions of a biphenyl skeleton. The highly twisted molecule conformation endows the compound excellent thermal stability with the glass transition temperatures of 170 oC and high triplet energy of 2.72 eV. In addition, BP-DPPI exhibits bipolar carrier transport ability for holes and electrons. The green phosphorescent OLED with BP-DPPI as host material exhibited the maximum external quantum efficiency (EQE) of 26.6% and power efficiency (PE) of 92.7 lm W-1. More importantly, the device shows low efficiency roll-off, which remains high values of 23.6 % for EQE at the routinely practical luminance of 1000 cd m-2.

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Publication details

The article was received on 23 Aug 2018, accepted on 05 Nov 2018 and first published on 07 Nov 2018


Article type: Paper
DOI: 10.1039/C8TC04218G
Citation: J. Mater. Chem. C, 2018, Accepted Manuscript
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    Twisted phenanthroimidazole based molecule with high triplet energy as host material for high efficiency phosphorescent OLEDs

    C. Li, Z. Li, J. Liang, H. Luo, Y. Liu, J. Wei and Y. Wang, J. Mater. Chem. C, 2018, Accepted Manuscript , DOI: 10.1039/C8TC04218G

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