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

In this experimental study, the effect of dyeconcentration on the optical properties of red-BS dyedopedpolyvinyl 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 glasssubstrate. Using transmission and reflection spectrum offilms, their optical parameter such as refractive index,absorption coefficient, and dielectric function are extractedand the effect of dye impurity on theses parameters hasbeen studied. The band gap energy of samples is calculatedusing Tauc method. Band gap energy of samples isdecreased by increasing the concentration of dye impurityin PVA films.