Beneficial effect of Se substitution on thermoelectric properties of Co4Sb11.9−xTexSe0.1 skutterudites

►Te and Se co-doped Co4Sb12−x−yTexSey compounds have been synthesized by the solid state reaction method. ► Doping of Se resulted in decrease of the lattice parameter and refinement of the particle size. ► The co-doped skutterudites show amazingly lower lattice thermal conductivity. ► Co-doping with Te and Se is an attractive approach to enhance the TE performance of skutterudites.