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Journal of Nanomaterials
Volume 2012 (2012), Article ID 674168, 9 pages
http://dx.doi.org/10.1155/2012/674168
Research Article

Electrochromic Devices Based on Porous Tungsten Oxide Thin Films

1Laboratoire de Recherche en Matériaux et Micro-Spectroscopies Raman et FTIR, Université de Moncton—Campus de Shippagan, 218 Boulevard J.-D. Gauthier, Shippagan, NB, Canada E8S 1P6
2Physics Department, Mount Allison University, 67 York Street, Sackville, NB, Canada E4L 1E6

Received 29 May 2012; Accepted 22 June 2012

Academic Editor: Vo-Van Truong

Copyright © 2012 Y. Djaoued 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

Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porous WO3 thin films with different nanocrystalline phases, such as hexagonal, monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porous WO3 thin films. XRD measurements of the intercalation/deintercalation of Li+ into/from the WO3 layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro-Raman studies show systematic crystalline phase changes in the spectra of WO3 layers during Li+ ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ~70%) due to intercalation/deintercalation of Li ions into/from the WO3 layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows.