Studying of the optical properties of poly (vinyl alcohol) films using different Metalssulphate as additivesby measuring allowed direct transition energy gap

Abstract

The change in the optical band energy gap have been investigatedfor pure Poly (vinyl alcohol)and Poly (vinyl alcohol) doped with different metalssulphate to proper films from their optical absorption spectra. The absorption spectra were measured in the wave rangefrom (200-800) nm at room temperature. The width of the tail of localized states in the band gap ($E_g$) was evaluated using the Urbach-edges method.