Preparation, investigation and application of nickel oxide thin films in flexible all-thin-film electrochromic devices: from material to device

• The target voltage vs. O 2 flux hysteresis curves were taken during reactive magneton sputtering. • All NiO X were reactively sputtered in the oxide mode zone at different working pressures. • The working pressure plays an important role on microstructure and composition of NiO X . • The flexible ATF-ECDs with ≥2 Pa NiO X layers perform the better device performances here. In this study, the nickel oxide (NiO X ) thin films were reactively sputtered at different working pressures in the oxide mode zone for application in flexible all-thin-film electrochromic devices (ATF-ECDs). The working pressure plays an important role on the various properties of the reactively sputtered NiO X thin film including the deposition rate, grain structure (microstructure), morphology, chemical composition, optical properties and electrochemical properties. The flexible ATF-ECDs with ≥2 Pa NiO X thin films perform high optical modulation and relatively fast response time during the electrochromic processes. The detailed electrochromic mechanism is discussed.