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International Journal of Photoenergy
Volume 2013 (2013), Article ID 437304, 5 pages
Research Article

Improved Efficiency of Flexible Organic Light-Emitting Diodes by Insertion of Ultrathin SiO2 Buffer Layers

1Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148, Taiwan
2Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 83160, Taiwan
3Department of Electro-Optical Science and Engineering, Kao Yuan University, Kaohsiung 82151, Taiwan
4Department of Electronic Engineering, National Formosa University, Hu-Wei, Yunlin 63201, Taiwan
5Department of Electrical Engineering, Southern Taiwan University of Technology, Tainan 71005, Taiwan

Received 15 September 2013; Accepted 3 October 2013

Academic Editor: Liang-Wen Ji

Copyright © 2013 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.


An ultrathin hole-injection buffer layer (HBL) using silicon dioxide (SiO2) by electron beam evaporation in flexible organic light-emitting diode (FOLED) has been fabricated. While the current of the device at constant driving voltage decreases as increasing SiO2 thickness. Compared to the different thicknesses of the buffer layer, the FOLED with the buffer layer of 4 nm showed the highest luminous efficiency. The atomic force microscopy (AFM) investigation of indium tin oxide (ITO)/SiO2 topography reveals changes at the interface between SiO2 and N,N′-bis-(1-naphthl)-diphenyl-1,1′-bipheny-4,4′-diamine (NPB), resulting in ultrathin SiO2 layers being a clear advantage for a FOLED. However, the SiO2 can be expected to be a good buffer layer material and thus enhance the emission performance of the FOLED.