Characterization and coloration efficiency studies using cyclicvoltammetry and chronocoulometric methods on TiO2 doped WO3 nanocrystalline thin films

Abstract

Using dc reactive magnetron sputtering, titanium doped WO3 thin films were deposited on various substrates at various oxygen partial pressures and temperatures and their optical, structural, morphological and electrochromic properties were investigated. At a sputtering pressure of 17.6 mTorr and a substrate temperature of 600 K, the optical transmittance of the films in the visible range is found to be up to 84%. As the sputtering pressure increased,the optical bandgap is observed to increase. X-ray diffractograms of the films showed sharp peaks from the reflections of (0 0 1) and (0 2 1) planes of monoclinic crystalline phase of WO3. The morphology studies revealed that titanium is incorporated into the films. Films were immersed in an anhydrous electrolyte to investigate their electrochromic properties. The diffusion coefficient of lithium ions and coloration efficiency were calculated using cyclicvoltammetry and chronocoulometric methods. Deposition parameters viz., the sputtering pressure and sputtering temperature were found to influence several parameters that include the thickness, transmittance, bang gap and refractive index of the films.