Fabrication of an all solid-state electrochromic device using zirconium dioxide as an ion-conducting layer

Highlights: • Optical and electrochromic (EC) behavior of ZrO₂ were studied. • The EC behavior of a half-cell structure of ZrO₂/NiO/ITO/glass was investigated. • An uniquely designed all-solid-state EC device was fabricated. • The large optical modulation was found to be 53% with the applied voltages of ±3 V. • The ZrO₂ film was used as Li⁺ ion conducting layer in the EC device. - Abstract: Zirconium dioxide (ZrO₂) thin films were deposited onto glass substrates, indium tin oxide (ITO) coated glass substrates and nickel oxide (NiO) / ITO / glass structures by reactive radio frequency (RF) magnetron sputtering using a zirconium target at room temperature. The deposition power was held at 75 W and the influence of deposition pressure and film thickness on the properties of the ZrO₂ films were investigated. Optical, electrochemical and electrochemical impedance spectroscopy measurements of the ZrO₂ films were performed and the electrochromic behavior of a half-cell structure of ZrO₂ / NiO / ITO / glass was investigated in a wide spectral range. The amount of inserted/extracted charges into/from each film during bleaching/coloring process were investigated in detail. The highest coloration efficiency (24.3 cm²/C) and optical modulation (42.8%) at a wavelength of 550 nm were found for a ZrO₂ / NiO / ITO / glass structure having a ZrO₂ film with a thickness of 100 nm, deposited at 4.00 Pa. Finally, a unique design of an all solid-state electrochromic device with a configuration of ITO / NiO / wet lithiated ZrO₂ / dry lithiated tungsten oxide (WO₃) / ITO / glass was fabricated. The optical modulation of the device was 53% at 550 nm for the applied potentials of ±3 V.