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Issue 30, 2014
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Highly efficient orange and deep-red organic light emitting diodes with long operational lifetimes using carbazole–quinoline based bipolar host materials

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Abstract

Orange and deep red-emitting phosphorescent organic light-emitting diodes (PhOLEDs) are important for OLED displays and lighting; however, high-performance with long operational lifetime hosts designed for orange/deep red PhOLEDs are very rare. Three new carbazole–quinoline hybrids are synthesized and used as the host materials for orange and deep-red PhOLEDs. These bipolar hosts show high glass transition temperatures of 90–146 °C and triplet energy gaps of 2.51–2.95 eV. The optimized orange PhOLEDs using 9-(4-(4-phenylquinolin-2-yl)phenyl)-9H-carbazole (CzPPQ) as the host show the highest external quantum efficiency (EQE) of 25.6% and a power efficiency of 68.1 lm W−1, which are the highest values for orange PhOLEDs. More importantly, the efficiency roll-off is extremely small for both the orange and deep-red devices. For example, an orange device showed an EQE of 25.1% at 100 cd m−2 and 23.6% at 1000 cd m−2; the result appears to be the lowest efficiency roll-off for orange PhOLEDs to date. Additionally, the operational lifetime of both the orange and deep-red devices gave a T50 of more than 26 412 and 11 450 h, respectively, at an initial luminance of 500 cd m−2. The values are 12 times (orange) and 6 times (red) longer than those of the corresponding devices using CBP as the host.

Graphical abstract: Highly efficient orange and deep-red organic light emitting diodes with long operational lifetimes using carbazole–quinoline based bipolar host materials

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Article information


Submitted
16 Mar 2014
Accepted
21 May 2014
First published
21 May 2014

J. Mater. Chem. C, 2014,2, 6183-6191
Article type
Paper
Author version available

Highly efficient orange and deep-red organic light emitting diodes with long operational lifetimes using carbazole–quinoline based bipolar host materials

C. Chen, L. Hsu, P. Rajamalli, Y. Chang, F. Wu, C. Liao, M. Chiu, P. Chou, M. Huang, L. Chu and C. Cheng, J. Mater. Chem. C, 2014, 2, 6183
DOI: 10.1039/C4TC00523F

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