Compositional dependence of optical parameters in Se-Bi-Te-Ag thin films

► The effect of Ag doping on the optical properties of Se-Te-Bi glasses are studied. ► The addition of Ag to Se-Te-Bi system makes the system stable. ► Optical band gap Eg is found to increases with the increasing concentration of Ag. ► Increase in Eg is ascribed to the increase in cohesive energy with Ag concentration.