Effect of 8 MeV electron irradiation on the optical properties of doped polymer electrolyte films

The effect of electron beam (EB) irradiation on the optical properties of cadmium chloride (CdCl2)-doped polyethylene oxide (PEO) is studied. The films are characterized using Fourier transform infrared spectroscopy (FTIR) in KBr medium. The morphology study of the films is conducted using a scanning electron microscope. The optical absorption study is carried out with the help of ultraviolet-visible absorption spectroscopy. The doped films are exposed to a beam of 8 MeV electron at 25, 50, 75, 100 kGy doses. The FTIR results of the films after EB irradiation shows the appearance of new peaks, and shifts in the position of peak prove the formation of hydrogen bonding. The optical absorption edges shift towards higher frequency upon EB irradiation, which indicates a lowering of the energy gap. This can be evidenced by the formation of carbonaceous clusters, which are estimated using the modified Tauc's equation. The optical parameters, namely absorption coefficient, optical direct and indirect band gaps (Eg), band edges and optical activation energy (Ea), are determined for different EB doses. These results reveal that the optical properties of the irradiated doped films are attributable to changes in the linear electronic polarizability of the material rather than its band gap or electronic structure. The obtained tunability in the optical properties of the EB-irradiated doped polymer electrolytes makes it of considerable interest in a number of optical applications.