Effect of dye concentration on the optical properties of red-BS dye-doped PVA film

In this experimental study, the effect of dye concentration on the optical properties of red-BS dye-doped polyvinyl alcohol (PVA) thin films is investigated. Three thin film samples with different concentration of red-BS dye were prepared by spin-coating method on the glass substrate. Using transmission and reflection spectrum of films, their optical parameter such as refractive index, absorption coefficient, and dielectric function are extracted and the effect of dye impurity on theses parameters has been studied. The band gap energy of samples is calculated using Tauc method. Band gap energy of samples is decreased by increasing the concentration of dye impurity in PVA films.