Effect of organic dyes on structural properties, linear optics and impedance spectroscopy of methyl orange (C.I. acid orange 52) doped polyvinyl alcohol composite thin films

Abstract

The effect of methyl orange (MEO) dye on structural properties, linear optics and impedance spectroscopy of the polymer poly(vinyl alcohol) (PVA) is studied. MEO/PVA composite thin film was prepared via casting technique. The changes in the structures of the samples were characterized by XRD, which revealed that the internal strain improved the growth of the crystal imperfection and distortion with increasing MEO content in the composite samples. The UV–Vis–NIR spectroscopy was used to study the effect of MEO organic on the optical properties of composite thin films. The samples enhanced more potent light UV–Visible absorption and have very effective prohibition UV-light effect even with incorporating MEO content in the range between 190 and 535 nm. The gap energy leads to a decrease in the visible region which could be attributed to the decrease in crystallite sizes with increasing MEO content. Normalized power characteristics of the films at various MEO concentrations were studied. The normalized power is the very interesting behavior to correlate the optical UV–Vis transmittance and the optics limiting effect of the samples. The dependence of frequency on the conductivity has analyzed in phases of an empirical Jonscher’s law. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements. Dielectric parameters infer that the incorporating MEO organic dye inside the PVA matrix may be affected by the faster charge transfer properties and behave like a non-ideal capacitor.