Effect of CuCl2 powder on the optical characterization of Methylcellulose (MC) polymer composite

Abstract

In this paper, polymer composite (PC) film based on Methylcellulose (MC) has been prepared by solution cast technique and its optical bandgap was discussed in detail. X-ray diffraction (XRD) method , UV–Vis absorption spectroscopy and Fourier transforms infrared spectroscopy (FTIR) technique were used to study the effect of different concentrations of copper chloride (CuCl2) salt on the structural and optical properties of the MC polymer. Scanning electron microscopy (FESEM) is used to examine the effect of CuCl2 on films morphology. The fundamental optical parameters, such as optical energy gap (Eg), optical dielectric constant (εr) and dielectric loss (εi) have been measured in which the amount of CuCl2 has significant effectiveness. Tauc’s relation was used to specifying the direct and indirect bandgap energy. The Eg of pure MC was considerably reduced from 6.21 to 2.68 eV by the addition of 20 wt% of CuCl2 salts. To specify the optical transition type, the exponent value of Tauc's law (γ) was identified by using the plot of εi against photon energy (hυ) to estimate the Eg value and specify the electronic transition type. For the composite samples, the Urbach energy (E0) increased, which can be evidence for a large possible number of tail-to-tail transitions. There is an increasing the refractive index (n) from 1.44 for pure MC to 2.04 upon the addition of 20wt.%CuCl2, indicating the occurrence of interaction between electrons and photons.