Optical, DC Conductivity and Electrochemical Parameter of Polymer Electrolyte Complexes*

Abstract

Here reporting the results of optical, dc electrical conductivity and electrochemical properties of lithium sulphate (Li2SO4) doped
polyethylene oxide (PEO) films have been studied. The pure and doped PEO films were prepared using solution casting technique at different weight percentages. The films are characterized through Fourier Transform Infra-red (FTIR) and Ultraviolet-visible (UV-Vis.)
Spectroscopy techniques. The dc electrical conductivity measurement was made by using two-probe technique at different temperatures. The fabrication of electrochemical cell in the configuration anode/polymer electrolyte/cathode and cell parameters was carried out using the Wagner polarization technique. The FTIR results noticed that there is a significant change in the intensities as well as frequencies of spectra and the appearance of new peaks confirm the better complexation of dopant with PEO. The UV–Vis. spectra reveal that the absorption bands positioned at different absorption intensities with addition of dopant. The optical band
gaps was evaluated using Tauc’s expression and band gap found decreases from 5.42 to 2.41eV (direct) and 4.79 to 4.20eV indirect. The
changes in the dipole strength, transition dipole moment, oscillator strength, and Urbach energy have been investigated with dopant
concentration. This may be explained on the basis of the fact that the incorporation of small amounts of dopant forms charge transfer
complexes in the host polymer matrix and established the complexation. The electrical conductivity was found increases with increasing of dopant concentration and estimated the electrochemical cell parameters OCV is 1.62V and SSC is 273μA. These obtained results suggest that these polymer systems are potential suitable candidates for solid state battery, optoelectronics display and electro chromic devises etc.