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Journal of Nanomaterials
Volume 2014, Article ID 915894, 6 pages
Research Article

Enhancing Color Purity and Stable Efficiency of White Organic Light Diodes by Using Hole-Blocking Layer

1Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung 81148, Taiwan
2Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 83160, Taiwan
3Department of Aviation & Communication Electronics, Air Force Institute of Technology, Kaohsiung 82044, Taiwan
4Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan

Received 18 May 2014; Accepted 4 June 2014; Published 17 June 2014

Academic Editor: Fu-Ken Liu

Copyright © 2014 Chien-Jung Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The organic light-emitting diodes with triple hole-blocking layer (THBL) formation sandwich structure which generate white emission were fabricated. The 5,6,11,12-tetraphenylnapthacene (Rubrene), (4,4′-N,N′-dicarbazole)biphenyl (CBP), and 4,4′-bis(2,2′diphenylvinil)-1,1′-biphenyl (DPVBi) were used as emitting materials in the device. The function of CBP layer is not only an emitting layer but also a hole-blocking layer (HBL), and the Rubrene was doped into the CBP. The optimal configuration structure was indium tin oxide (ITO)/Molybdenum trioxide (MoO3) (5 nm)/[4,4-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) (35 nm)/CBP (HBL1) (5 nm)/DPVBi (I) (10 nm)/CBP (HBL2) : Rubrene (4 : 1) (3 nm)/DPVBi (II) (30 nm)/CBP (HBL3) (2 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen) (10 nm)/Lithium fluoride (LiF)/aluminum (Al). The result showed that the device with Rubrene doped in CBP (HBL2) exhibited a stable white emission with the color coordinates of (0.322, 0.368), and the coordinate with the slight shift of = (0.001, 0.011) for applied voltage of 8–12 V was observed.