Variation of Optical Band Gap Width of PVA Films Doped with Aluminum Iodide

Polymer composite of polyvinyl alcohol (PVA), Aluminum Iodide have been prepared by solution cast method for different doping concentrations. The absorption of pure and doped films have been investigated in the visible and ultraviolent wavelength regions. It was found that the optical absorption is due to direct and indirect transitions, and the optical energy gaps values shifted to lower energies on Aluminum Iodide doping concentration for all transitions, while the band edge width of the tail localized states increase with increasing Aluminum Iodide concentration. The band gap of all films shows to be decrease after thermal treatment. The optical constants refractive index n, extinction coefficient k, the complex dielectric constant have been also calculated. The dielectric constant increased in the composite samples as compared with the pure PVA sample prepared by the same method.