Structural and optical properties of PVA/PVP polymer blend nanocomposite membrane reinforced with Zn0.08Cd0.92O nanoparticles for potential flexible optoelectronic applications

Abstract

PVA/PVP polymer blend nanocomposite films incorporating Zn 0.08 Cd 0.92 O nanoparticles at concentrations ranging from 0.3 to 2.0 wt% were fabricated via the solution casting method. The structural, morphological and optical properties of the prepared films were systematically investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and ultraviolet-visible spectroscopy. Diffraction analysis confirmed the amorphous nature of the pure PVA/PVP blend and revealed the progressive emergence of the cubic Zn 0.08 Cd 0.92 O crystalline phase with increasing filler content. The crystallite size decreased progressively from 38.1 nm at 0.7 wt% to 32.6 nm at 2.0 wt%, accompanied by a corresponding increase in dislocation density and lattice strain, indicating growing structural distortion at higher loadings. Infrared spectra confirmed chemical compatibility between the nanoparticles and the polymer matrix through hydrogen bonding and surface coordination interactions. Electron microscopy showed that low filler concentrations yielded smooth, homogeneous films, while higher concentrations induced surface roughening and localized nanoparticle aggregation without compromising film integrity. Optical analysis demonstrated a systematic redshift of the absorption edge and a reduction in both direct (from 5.27 to 5.23 eV) and indirect (from 5.10 to 4.97 eV) optical band gaps, while the Urbach energy increased from 0.48 to 0.60 eV, indicating a growth of localized band-tail states consistent with the structural disorder observed by diffraction. The refractive index, dispersion energy, oscillator strength and optical susceptibilities were all enhanced with increasing filler loading, the refractive index rising from 1.88 to 2.70 and the estimated third-order nonlinear susceptibility from 2.91 × 10 −13 to 108.61 × 10 −13 esu. These optical characteristics indicate the potential of PVA/PVP/Zn 0.08 Cd 0.92 O nanocomposite films for optical coating and flexible optoelectronic applications.