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International Journal of Photoenergy
Volume 2014, Article ID 412084, 7 pages
http://dx.doi.org/10.1155/2014/412084
Research Article

Improvement in Device Performance and Reliability of Organic Light-Emitting Diodes through Deposition Rate Control

1Department of Electronic Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan
2Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
3Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 106, Taiwan
4Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
5Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
6Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan

Received 25 February 2014; Revised 9 April 2014; Accepted 10 April 2014; Published 27 April 2014

Academic Editor: K. R. Justin Thomas

Copyright © 2014 Shun-Wei Liu 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

We demonstrated a fabrication technique to reduce the driving voltage, increase the current efficiency, and extend the operating lifetime of an organic light-emitting diode (OLED) by simply controlling the deposition rate of bis(10-hydroxybenzo[h]qinolinato) beryllium (Bebq2) used as the emitting layer and the electron-transport layer. In our optimized device, 55 nm of Bebq2 was first deposited at a faster deposition rate of 1.3 nm/s, followed by the deposition of a thin Bebq2 (5 nm) layer at a slower rate of 0.03 nm/s. The Bebq2 layer with the faster deposition rate exhibited higher photoluminescence efficiency and was suitable for use in light emission. The thin Bebq2 layer with the slower deposition rate was used to modify the interface between the Bebq2 and cathode and hence improve the injection efficiency and lower the driving voltage. The operating lifetime of such a two-step deposition OLED was 1.92 and 4.6 times longer than that of devices with a single deposition rate, that is, 1.3 and 0.03 nm/s cases, respectively.