Optical and Conductivity Studies of Cr3+ Doped Polyvinyl Pyrrolidone Polymer Electrolytes

Polymer electrolyte films of polyvinyl pyrrolidone (PVP) embedded with various concentrations of Cr3+ ions were prepared by a solution casting technique. The complexation between the Cr3+ ions and the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy and UV-vis spectroscopy. The electrical conductivity of the films was measured using an impedence analyzer in the frequency range of 42 Hz to 5 MHz at ambient temperature. It was observed that the conductivity increased with the increase in the Cr3+ ion concentration. UV-visible absorption spectra in the wavelength range of 200-800 nm were used to determine the direct and indirect optical energy band gaps and optical absorption edge. Both of the optical band gaps decreased with the increase in Cr3+ ion concentration. FTIR studies on pure and Cr3+ doped PVP polymer films revealed the vibrational changes that occurred due to the effect of the dopant Cr3+ ions in the polymer. Our results suggested that Cr3+, as a dopant, is a good choice to improve the electrical properties of PVP polymer electrolytes.