Reactive Sputtering Deposition of a-WO3-z on Flexible PET/ITO Substrates for Electrochromic Devices

Abstract

The deposition of electrochromic thin films of a‐WO3‐z (amorphous tungsten oxide) on flexible PET (polyethylene terephthalate)/ITO (indium tin oxide) substrates by a reactive radio frequency (r.f.) sputtering method was investigated. The method used argon and oxygen at room temperature (23 °C). Cyclic voltammetry measurements showed that only low driving voltages −1 and +1 V were needed to provide reversible Li+ ion insertion and extraction. Cyclic potentiostatic switching and visible–UV spectroscopy showed that thin films with oxygen deficiency z of 0.22 can offer excellent light modulation, with up to 62% transmittance variation and color efficiency of 61.3 cm2 · C−1.