Stable and reversible electrochromic behaviors in anodic NiO thin films

Abstract

We report the synthesis and electrochromic behavior of nickel oxide (NiO) nanostructures deposited over conducting glass substrates by hot-filament metal vapor deposition (HFMVD). The NiO crystallized into rhombohedra structure with R3-m space group without any post-treatment. The cyclic voltammogram (CV) revealed the coloration and bleaching effect of NiO nanostructures with forward and reverse scans, respectively. The 85.05% reversibility for NiO films from the coloration state back to its bleached state was calculated from Chronocoulometry (CC) measurements. The highest optical transmittance difference obtained at 420 nm has resulted in a corresponding optical density of 1.016. The switching time between the coloration and bleaching cycles calculated from transmittance spectra unfolded the lowest coloration time of 4.96 sec at 354 nm, which increased up to 6.32 sec at 590 nm, whereas the bleaching time at all the wavelengths was estimated to be less than 0.5 sec.