WO3 thin films were fabricated by RF sputtering deposition. The as-deposited thin films showed uniformity and good adhesion to an ITO layer. The deposition rate increased as the applied power was increased during the RF sputtering deposition. While the as-deposited WO3 thin films deposited in argon gas alone had very low stoichiometry showing a degradation phenomenon during the transmittance measurement, the WO3 thin film deposited in a mixture of argon and oxygen gases exhibited better cyclability and afaster response time. The WO3 thin film prepared at 800 W in the gas mixture showed the best performance with a coloration efficiency of 30.2 cm2 • C-1 and a coloring response time of 7 s.

Keywords: Electrochromic materials, RF sputtering, Tungsten trioxide, Transmittance, Coloration efficiency.