Polymer assisted deposition of electrochromic tungsten oxide thin films

We report the synthesis of structurally and uniformly deposited porous tungsten oxide (WO3) thin films for the first time by the novel route of polymer assisted deposition (PAD) using ammonium tungstate as a precursor with polyvinyl alcohol (PVA) as an additive. The effect of deposition parameters on the morphological, optical and electrochemical performance of the thin films is investigated. WO3 thin films were characterized for their structural, morphological, optical and electrochromic properties. XRD result indicates monoclinic phase of WO2.92. FT-Raman studies show high intensity peaks centered at 997 cm-1and 798 cm-1. SEM results indicate that there is uniform deposition of porous WO3-PVA agglomerates on the transparent substrates. SEM data show low dense structure of an average grain size of about 1 μm. Electrochromic studies reveal highly reversible and the stable nature of the thin films. Transmission data show an optical modulation density of 46.57% at 630 nm with an excellent reversibility of 89% and an electrochromic coloration efficiency of 36 cm2/C.