Optical properties of thermally evaporated Bi2Se3 thin films treated with AgNO3 solution

► Ag/Bi2Se3 thin films have been prepared by ion exchange process. ► Diffusion of Ag into Bi2Se3 layer occurs at an annealing temperature of 473 K. ► The optical band gap decreases in a reverse manner to the refractive index. ► The obtained results permit us to design partial reflective mirrors.