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Proceedings Paper

Efficiency improvement of yellow organic light-emitting devices by using mixed hole transporting layer
Author(s): Sujie Chen; Junsheng Yu; Wen Wen; Yadong Jiang
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Paper Abstract

Organic light-emitting devices (OLEDs) with a novel metal iridium complex of bis[2-(4-tertbutylphenyl) benzothiazolato-N,C2'] iridium (acetylacetonate) [(t-bt)2Ir(acac)] doping into a carbazole-based material 4,4'-bis[N-1-napthyl-N-phenyl-amino]biphenyl (CBP) as light-emitting layer (ETL) were fabricated. The optimum doping concentration of (t-bt)2Ir(acac) phosphor was 8 wt%. The maximum power efficiency (ηp) of the OLED was 8 lm/W. Furthermore, to improve the balance of charge carriers and enhance the ηp of the device, a doping system consisted of NPB hole transporting material and CBP host material with a concentration proportion of 1:3 was employed as the mixed hole transporting layer. OLEDs with a structure of indium-tin oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'- biphenyl-1,1'-biphenyl-4,4'-diamine (NPB):CBP(1:3)/CBP:(t-bt)2Ir(acac)/2, 9-dimethyl-4, 7-diphenyl-phenanthroline (BCP)/Mg:Ag were fabricated. The results showed that current density was decreased and the maximum ηp of the device was 10.6 lm/W. Compared with the conventional device with NPB as hole transporting layer, the improved maximum ηp of the device with mixed hole transporting layer was increased 32.5 %. This is attributed to the reduction of hole injection amount and transporting mobility by doping material CBP in hole transporting layer, which significant enhances charge carrier balance and electron-hole recombination probability.

Paper Details

Date Published: 22 October 2010
PDF: 5 pages
Proc. SPIE 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, 76583Z (22 October 2010); doi: 10.1117/12.867248
Show Author Affiliations
Sujie Chen, Univ. of Electronic Science and Technology of China (China)
Junsheng Yu, Univ. of Electronic Science and Technology of China (China)
Wen Wen, Univ. of Electronic Science and Technology of China (China)
Yadong Jiang, Univ. of Electronic Science and Technology of China (China)


Published in SPIE Proceedings Vol. 7658:
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology

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