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

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 x 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. (C) 2019 Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.