Microstructural, optical and electrochromical properties of W-doped Nb2O5 thin films prepared by dip-coating process using sols obtained by the chloroalkoxide route

Undoped and W-doped Nb 2 O 5 thin films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to study the influence of W doping on their structural and morphological properties. The synthesized Nb 2 O 5 thin films have been found to possess an orthorhombic crystal structure having crystallite sizes 10–31 nm. The UV–visible spectroscopy shows the optical bandgap ~ 3.60 eV. The cyclic voltammetric studies show that the colouration efficiency of the films improves upon W doping with the optimum value of 68.7 cm 2 /C at 600 nm for the 3 at.% W-doped film. The chronoamperometric studies reveal that the switching response of the films becomes better upon W doping. The electrochemical impedance spectroscopy (EIS) data has been analyzed by fitting it to the equivalent electrical circuit (EEC) using Nova software.