Electrochromic properties of sputtered nickel-oxide films

Abstract

Electrochromic properties of nickel-oxide films have been investigated. Films were prepared by rf sputtering from a compressed powder NiO target in an atmosphere of an Ar-O2 mixture. The deposition rate of the nickel oxide decreased when the total pressure of the sputtering atmosphere was increased, but was independent of the oxygen content. The films obtained can be electrochemically colored and bleached in a 1-N NaOH electrolyte solution, and are colored anodically. The colored film is dark brown, and the bleached one is transparent and colorless. The maximum coloration efficiency is obtained with the films prepared at the total pressure of 0.04 Torr, and is 36 cm2/C at a wavelength of 640 nm. Coloration efficiency is independent of oxygen content in the sputtering atmosphere.