Optimization of deposition rate for E-beam fabricated tungsten oxide thin films towards profound electrochromic applications

In the past few decades, there has been a jet of interest in adopting tungsten oxide (WO3) thin films as an active layer in electrochromic applications. The central objective of this work is to optimize the deposition rate for E-beam fabricated WO3 thin films yielding an idealized thin film towards profound electrochromic applications. In this regard WO3 thin films were fabricated at three deposition rates 0.5A(o)/s, 1.5A(o)/s and 3A(o)/s on fluorine-doped tin oxide (FTO) coated substrates and corning glass substrates, using e-beam evaporation technique. Films were fully characterized for morphological, structural, optical, electrochemical and electrochromic attributes by Scanning Electron Microscope (SEM), X-ray Diffractometer (XRD), UV-Visible spectroscopy, Cyclic Voltametric (CV) characterization techniques, respectively. SEM characterization stipulated the formation of nanospheres which grew as nanoclusters at a deposition rate of 1.5A(o)/s. Energy dispersive spectroscopy (EDS) analysis diagnosticate tungsten and oxygen as two elements present in appropriate atomic percentage values revealing towards purity of the films. XRD analysis postulated towards the amorphous nature of all the as deposited films. Optical transmittance of as deposited films varied from 60 to 65% within the wavelength range of 400 nm to 600 nm. Optical energy band gap value was least at 3.11 eV for the film grown at deposition rate 1.5A(o)/s. Highest coloration efficiency and diffusion co-efficient were found to be 17.50 cm(2)/C and 3.26 x 10(-4) cm(2)/s, respectively, for the film fabricated at deposition rate of 1.5A(o)/s. Overall it was witnessed that all the characterization techniques were judiciously whispering to contemplate 1.5A(o)/s as an optimized deposition rate to fabricate WO3 thin film towards profound electrochromic application under present experimental condition.