New thin films of NiO doped with V2O5 for electrochromic applications

Abstract This paper reports on synthesis and characterization of new electrochromic thin films of NiO doped with V 2 O 5 that were prepared by the sol-gel method and deposited by the spin coating technique. The confirmation of the presence of the dopant in the structure of the films was given by energy-dispersive X-ray spectroscopy (EDX). The effect of the addition of vanadium to the films of NiO was evaluated by electrochemical techniques such as cyclic voltammetry, chronocoulometry, and chronoamperometry in 0.5 mol/L KOH electrolyte. The morphology and the structure of the films, determined by microscopies (SEM and AFM), reveal smooth and slightly rough surfaces. The addition of vanadium as a dopant does not produce changes in the host NiO matrix as evidenced by X-ray diffractometry (XRD). However, the addition of the dopant causes a significant improvement in a charge density values of the films that increase more than twice from 25.5 mC/cm 2 for NiO to 52.8 mC/cm 2 for NiO with 10 mol% of V 2 O 5 . V 2 O 5 doping of NiO films also improved their optical properties as well as kinetics of insertion and extraction processes.