Electrochromic properties of tungsten oxide films prepared by sparking method using external electric field

• Main Authors: W. Thongpan, D. Louloudakis, P. Pooseekheaw, T. Kumpika, E. Kantarak, A. Panthawan, A. Tuantranont, W. Thongsuwan, P. Singjai
• Format: Journal
• Published: 2019
• Subjects: Materials Science; Physics and Astronomy
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85065018115&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/65662
• Institution: Chiang Mai University

© 2019 Elsevier B.V. In this paper, high porous tungsten oxide (WO 3 )films were prepared onto indium-doped tin oxide glass substrates by a sparking method, which is a simple and cost-effective technique. An external electric field of 6 kV/cm was applied to the sparking system in order to increase a dense surface morphology and the deposition rate of the films. In experiments, the films were deposited for 20 min at room temperature and post-annealed from 200 to 500 °C for 1 h under atmospheric pressure. High porosity of the WO 3 films was fabricated by the sparking method and confirmed by scanning with electron microscopy. Raman spectra and X-ray diffraction patterns show the monoclinic phase of WO 3 when the annealing temperature is higher than 300 °C. In addition, the electrochemical analysis was carried out by using a 0.05 M H 2 SO 4 electrolyte solution, Pt as a counter electrode, and Ag/AgCl as a reference electrode. The fast switching speeds of 1.2 s and 2.6 s (for the coloration and bleaching state respectively), optical modulation of 16.3%, and coloration efficiency of 49.6 cm 2 /C were achieved for annealed films at 300 °C.