Determination of optical parameters of zinc oxide nanofibre deposited by electrospinning technique

Electrospun ZnO was deposited on a glass substrate from zinc acetate dihydrate (Zn(CH3COO)2.2H2O) with polyvinyl acetate (PVAc) polymer dissolved in N, N, dimethyl formamide (DMF) and annealed in the presence of oxygen until organic molecules were decomposed. The resultant fibre was characterized using scanning electron microscope with energy dispersive spectrophotometry (SEMEDS), Fourier transform infrared (FTIR), and Rutherford backscattering spectroscopy (RBS). SEMEDS and FTIR exhibited a total decomposition of the organic precursor. The mean fibre width was found to be 260 nm, and fibre thickness was measured at 460 nm. XRD patterns indicate that ZnO was corundum with the hexagonal wurtzite structure. The crystallite size was determined by the Debye formula to be 54 nm. The optical analysis indicated that the percentage transmittance increased after calcination. The material band gap for this electrospun ZnO fibre was found to be 3.28 eV. The material optical parameters such as dispersion energy, average oscillator strength, and single oscillator strength were also calculated. The optical conductivity and dielectric plot demonstrated that the material conductivity and dielectric properties increase with increasing photon energy and increase sharply around the material energy bandgap. The Urbach tail analysis of the materials shows that they obey the Urbach rule. Therefore, the n-type electrospun ZnO fibre high refractive index is attributable to the presence of excess oxygen.