Properties of WO3-x Electrochromic Thin Film Prepared by Reactive Sputtering with Various Post Annealing Temperatures

Abstract

The WO3-x thin films were prepared on indium tin oxide (ITO) coated glass at 0.7 oxygen flow ratio [O-2/(Ar + O-2)] using the facing targets sputtering (FTS) system at room temperature. In order to obtain the annealing effect, as-deposited thin films were annealed at temperatures of 100, 200, 300, 400, and 500 degrees C for 1 h in open air. The structural properties of the WO3-x thin film were measured using an X-ray diffractometer. The WO3-x thin films annealed at up to 300 degrees C indicated amorphous properties, while those annealed above 400 degrees C indicated crystalline properties. The electrochemical and optical properties of WO3-x thin films were measured using cyclic voltammetry and a UV/vis spectrometer. The maximum value of coloration efficiency obtained was 34.09 cm(2)/C for thin film annealed at 200 degrees C. The WO3-x thin film annealed at 200 degrees C showed superior electrochromic properties. (C) 2013 The Japan Society of Applied Physics