Study of optical and dielectric constants of hybrid SnO₂ electrospun nanostructures

The aim of this paper was to prepare SnO₂ nanowires using electrospinning and calcination processes from a poly(vinylpyrrolidone), dimethylformamide, ethanol and tin(IV) chloride pentahydrate solution. The composite PVP/SnCl₄ nanofibers obtained via electrospinning method were dried and calcined in a vacuum to remove the polymer matrix at a temperature of 500 °C for 10 h. Three types of nanowires with a polymer to precursor ratios of 2:1, 1:1, 1:3 were produced. The morphology and chemical composition of as-spun PVP/SnCl₄ nanofibers and SnO₂ nanowires obtained after heat treatment were carried out using a scanning electron microscope (SEM) with an energy-dispersive spectrometer (EDX). The Fourier-transform infrared spectroscopy (FTIR) spectra of the prepared nanomaterials were also investigated. To determine the topography of PVP/SnCl₄ nanofibrous mats, an atomic force microscope (AFM) was used. A 100-fold measurement of the nanowire size showed that, depending on the amount of precursor in the spinning solution, nanowires with diameters ranging from 20 to 260 nm were obtained. The optical property analysis was performed on the basis of absorbance spectra recorded over UV–Vis spectral range. The complex refractive index n and complex dielectric permeability ε of obtained tin oxide nanowires were determined as a function of the radiation energy. Depending on the precursor content in spinning solution, the one-dimensional SnO₂ nanostructures were characterised by a refractive index in the range of 1.51–1.56, whereas the dielectric constant ranged from 2.26 to 2.30. The optical properties and the structure of one-dimensional SnO₂ nanomaterials allow to use this type of materials in the construction of novel type photovoltaic cells and electronic devices.