Preparation, structural characterization, optical, photoluminescence, AC electrical conductivity and broadband dielectric properties of WO3 reinforced PEG/CS blend for futuristic optoelectronic and energy storage devices

Abstract

Polymer nanocomposites (PNCs) composed of biopolymers and metallic oxides are important classes of materials. In addition to the environmental and economic considerations, these materials became the best candidates for various industrial fields. In the current study, solution cast procedure is used to prepare polymer nanocomposites (PNCs) based on polyethylene glycol (PEG)/chitosan (CS) blend and varying concentrations of tungsten trioxide nanoparticles (WO3 NPs), as a nanofiller. TEM micrograph shows that WO3 NPs have particle sizes of 5–32 nm their shapes are cubic and spherical. The XRD results reveal the semicrystalline of PEG/CS blend through showing three distinct diffraction peaks at 2θ = 7.42°, 19.47° and 23.62° and the degree of crystallinity is decreased after the incorporation of WO3 NPs due to the formation of polymer-nanoparticle interactions as indicated by FTIR spectra. The values of optical energy bandgap (direct and indirect) reduce while the Urbach energy increases with raising the concentration of WO3 NPs in the PEG/CS matrix. The PEG/CS-WO3 films' PL spectra show a photoemission peak at about 387 nm, where this peak loses intensity and becomes broader due to the induced defects and increase of disordering within the nanocomposite films. Additionally, the results of the dielectric investigation show an increase in the dielectric constant, dielectric loss, and AC electrical conductivity, which may be a sign of an increase of charge carriers and the content of amorphous regions that assists the movement of charge carriers. The DC electrical conductivity and conduction mechanism are also reported. Argand plot shows a half semicircle implying the Debye-type relaxation mechanism. The experimental results suggest the use of PEG/CS-WO3 nanocomposites as a possible contender for futuristic energy storage and optoelectronic applications.