Studies on Electrochromism of Chemically Deposited Nickel Oxide Thin Films

Abstract

In this work, nickel oxide (NiO x ) thin films were prepared from aqueous solution of nickel nitrate and carbamide. Those films were deposited onto fluorine doped tin oxide (FTO) coated glass substrates. An electrochromic test device (ECTD) was constructed by using these films as working electrodes, and FTO coated glass as an opposite electrode in alkaline medium of 0.1 M NaOH aqueous solution. The obtained nickel oxide films exhibited anodic electrochromism, changing color from transparent to dark brown. Various techniques were used for characterization of the films as x-ray diffraction (XRD), visible spectroscopy and electrochemical methods. The dependence of the optical density on the charge density was examined and the coloration efficiency was calculated from the optical density change. The time response was also determined.