Improved electrochromic performance in nickel oxide thin film by Zn doping

Abstract

Zn-doped NiO thin films were prepared using the simple sol-gel spin-coating method and their electrochromic characteristics were compared with undoped NiO thin film. The transparency in the visible region and uniformity of the NiO thin films were enhanced with increasing Zn doping amounts. The in situ optical transmittance spectra revealed all samples were transparent at bleached state, whereas the color changed from light brown to dark brown at a colored state, as the Zn doping amounts increased. The Zn-doped NiO thin film exhibited a higher transmittance change (ΔT) of 59.8% and higher color efficiency (CE) of 33.6 cm2/C at a wavelength of 500 nm compared with the undoped film (22.4% (ΔT) and 27.3 cm2/C (CE). Moreover, it displayed a sustained memory effect under open circuit. The addition of the Zn dopant offered a simple way to improve the electrochromic performance of the NiO thin film.