Novel Trizazole-carbazole Based Host Material for Sky-blue Electrophosphorescent Devices

doi:10.7517/j.issn.1674-0475.2017.04.033

Imaging Science and Photochemistry ›› 2017, Vol. 35 ›› Issue (5): 729-735.DOI: 10.7517/j.issn.1674-0475.2017.04.033

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Novel Trizazole-carbazole Based Host Material for Sky-blue Electrophosphorescent Devices

WANG Fang, LI Jiuyan

State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, P. R. China

Received:2017-06-01 Revised:2017-06-13 Online:2017-09-15 Published:2017-09-15

Abstract

Abstract:

Phosphorescent organic light-emitting diodes (OLEDs) are advantageous over the traditional fluorescent ones in terms of high efficiency by harvesting both singlet and triplet excitons for light emission. Transition-metal complex phosphors must be dispersed in a certain host matrix to suppress the concentration quenching and triplet-triplet annihilation. Therefore, the host material is as important as the dopant emitter in phosphorescent OLEDs. In this report, a novel host material, oCzTz, was developed by using 1,2,4-triazole as the n-type unit and carbazole as the p-type unit. Ortho-substitution was applied to reach a twisted molecular configuration, which finally leads to high triplet energy of 3.01 eV for oCzTz. oCzTz has high thermal decomposition temperature of 353℃ and glass transition temperature of 110℃. The theoretical calculation results showed that the HOMO and LUMO are highly separated, indicating its bipolar charge transporting feature. oCzTz was used as host material to fabricate sky-blue phosphorescent OLED with FIrpic as the doped emitter, which exhibited a low turn-on voltage of 3.4 V, the high current efficiency of 37.2 cd·A^-1 and the power efficiency of 29.2 lm·W^-1. These are one of the highest efficiencies among the sky-blue phosphorescent OLEDs with TPBI as electron transporting layer.

Key words: organic light-emitting diodes (OLEDs), bipolar host materials, 1,2,4-triazole, sky-blue electrophosphorescence

WANG Fang, LI Jiuyan. Novel Trizazole-carbazole Based Host Material for Sky-blue Electrophosphorescent Devices[J]. Imaging Science and Photochemistry, 2017, 35(5): 729-735.

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Novel Trizazole-carbazole Based Host Material for Sky-blue Electrophosphorescent Devices

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