Effect of Co60γ-irradiation on the optical properties of thin films from the system GeSe3-Sb2Se3-ZnSe

► GeSe3-Sb2Se3-ZnSe thin films were prepared by thermal evaporation technique. ► The influence of γ-irradiation on the optical properties of the thin films is investigated. ► A change in the optical energy gap is observed after irradiation. ► The results are discussed in terms of localized states and cohesive energy.