Optical and electrical conductivity studies of VO2+ doped polyvinyl pyrrolidone (PVP) polymer electrolytes

Abstract

Polymer electrolyte films of polyvinyl pyrrolidone (PVP) complexed with different concentrations (1, 2, 3, 4 and 5 mol%) of VO2+ ions were prepared by a solution casting technique. The formation of complexes between the VO2+ ions and the polymer was confirmed by the Fourier transform infrared spectroscopy (FTIR) and the UV-Vis spectroscopy. Room temperature impedance measurements in the frequency range 42 Hz to 5 MHz revealed that the ionic conductivity increased with the increasing the VO2+ ion concentration. The maximum ionic conductivity of 5.39 × 10−8 Scm−1 at 303 K was observed for the 5 mol% VO2+ ions doped PVP polymer electrolyte film. From the UV-Visible absorption spectra in the wavelength range of 200–800 nm the direct and indirect optical energy band gaps and optical absorption edges were found decreased with the increase in the VO2+ ion concentration. FTIR studies on pure and VO2+ doped PVP polymer films revealed the vibrational changes to occur due to the effect of the dopant VO2+ ions in the polymer. It is suggested that VO2+, as a dopant, is a good choice to improve the electrical properties of the PVP polymer electrolyte. Keywords: Polymer electrolytes, Polyvinyl pyrrolidone, FTIR, UV - Visible, Polymer electrical conductivity, Optical energy band gaps