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Optimization of white organic light emitting diodes based on emitting layer charge carrier conduction properties

Cited 20 time in Web of Science Cited 21 time in Scopus
Authors
Baek, H. I.; Lee, Changhee
Issue Date
2008
Publisher
IOP Science
Citation
J. Appl. Phys. D: Appl. Phys. 41 105101
Abstract
We have fabricated white organic light emitting diodes (OLEDs) with multi-emitting layer (EML) structures in which 4,4'-N,N'-dicarbazole-biphenyl (CBP) layers doped with the phosphorescent dopants fac-tris(2-phenylpyridine) iridium (Ir(ppy)3) and bis(2-(2'-benzo[4,5-a]thienyl)pyridinato-N,C3')iridium(acetylacetonate) (btp2Ir(acac)) and the fluorescent dopant 4,4'-bis[2-{4-(N,N-diphenylamino) phenyl}vinyl]biphenyl (DPAVBi) were used as green (G), red (R) and blue (B) EMLs, respectively. A higher efficiency was expected with the R/G/B EML sequence from the hole transport layer interface than with the G/R/B sequence because of the differences in the charge carrier conduction properties of the EMLs doped with phosphorescent dopants and the luminance balance between the phosphorescent and fluorescent emissions. A high efficiency of 18.3 cd A−1 (an external quantum efficiency of 8.5%) at 100 cd m−2 and good colour stability were achieved with the R/G/B EML sequence as expected, with an additional non-doped CBP interlayer used between the G and B EMLs. In addition, the OLED with this sequence was found to have the longest lifetime of the white devices we tested.
ISSN
0022-3727
Language
English
URI
http://hdl.handle.net/10371/13663
DOI
https://doi.org/10.1088/0022-3727/41/10/105101
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Electrical and Computer Engineering (전기·정보공학부)Journal Papers (저널논문_전기·정보공학부)
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