Tungsten Disulfide Wrapped WO3 Based Thin Film Transparent Electrode Material for Electrochromic Device Application

Abstract

We report the detailed investigation of tungsten disulfide (WS2) wrapped tungsten trioxide (WO3) nanocomposites as electrode materials for electrochromic devices. The WS2/WO3 nanocomposite was prepared by exfoliation of WS2 in WO3, where WO3 was prepared by acidic co-precipitation technique. X-ray diffraction spectra were used to study the structural properties of the prepared materials. The results show that agglomeration due to pinning of grain boundaries by WS2 leads to an increase in the crystallite size of the nanocomposites, confirming the formation of WS2/WO3. Field-emission scanning electron microscopy and high-resolution tunnelling electron microscpy were used to study the nanocomposites morphology. The results show that the relative distribution of nanoparticles is more uniform compared to WO3 after the addition of WS2. The shape of WO3 changes from spherical to square nanosheets with good dispersion. The electrochemical properties of the prepared samples were investigated by chronoamperometry, charge/discharge,and cyclic voltammetry. The lower peak separation between oxidation and reduction resulted from the fact that the peaks of the anodic and cathodic current densities of the nanocomposite (WS2/WO3) were shifted more to higher and lower potentials, respectively. This suggests faster charge transfer kinetics. UV/Vis spectroscopy was used to investigate the electrochromic and optical properties of the fabricated ECDs. The WS2/WO3-based ECDs exhibit a high colouring efficiency of 61 cm2C−1. The study shows that ECDs based on WS2/WO3 exhibit better electrochromic performance compared to WO3 ECDs.