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International Journal of Photoenergy
Volume 2013, Article ID 878537, 6 pages
http://dx.doi.org/10.1155/2013/878537
Research Article

The Investigation on Color Purity of Blue Organic Light-Emitting Diodes (BOLED) by Hole-Blocking Layer

1Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 83160, Taiwan
2Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148, Taiwan
3Department of Electronic Engineering, National Formosa University, Huwei, Yunlin 63201, Taiwan
4Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
5Department of Electrical Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan

Received 18 October 2013; Accepted 31 October 2013

Academic Editor: Teen-Hang Meen

Copyright © 2013 Kan-Lin Chen 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.

Abstract

Organic light-emitting diodes (OLEDs) with triple hole-blocking layer (THBL) structure, which consist of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,4′-bis(2,2′diphenyl vinil)-1,1′-biphenyl (DPVBi), and (4,4′-N,N′-dicarbazole)biphenyl (CBP), have been fabricated. Regardless of applied voltage variation, the luminous efficiency of the OLEDs with THBL structure was increased by 41% as compared with the dual hole-blocking layer (DHBL) structure. The CIE coordinates of (0.157, 0.111) of device with THBL structure are close to pure blue emission than that of other devices of DHBL. There is a coordinate with the slight shift of = (0.001, 0.008) for the device with THBL structure during the applied voltage of 6–9 V. The results indicate that the excitons can be effectively confined in the emitting layer of device, leading to an enhancement of luminance efficiency and more stable coordinate.