Enhanced thermoelectric properties of Cu2-xSe by coordinating carrier concentration to reduce thermal conductivity

Cu 2-x Se has been known as an ideal thermoelectric material for application in the middle-high temperature range due to the outstanding electric transmission conductivity and relatively low lattice thermal conductivity. However, its performance is significantly constrained by its high thermal conductivity and thermal stability issues, as well as its difficulty in element doping because of the influence of atomic size and atomic solid solubility. Here, we prominently reduced the thermal conductivity of Cu 2-x Se by addition different amounts of WS 2 to the Cu 2-x Se matrix, and successfully improved the power factor of the material because of the reduction of high Cu defects to coordinate the three mutually coupled parameters. The zT value of the WS 2 -doping Cu 2-x Se sample was eventually enhanced by 56% compared with pristine Cu 2-x Se, and up to ca. 1 at 823 K. Further, we found that the symmetry of the Cu 2-x Se crystal had not been destroyed undergoing the doping of WS 2 into its crystal lattice, and the doped sample showed good thermal stability when cycle test was carried out twice between 315 K and 823 K. Cu 2-x Se were prepared by colloidal synthesis, and it's thermal conductivity was reduced by doping with different amounts of WS 2 into the Cu 2-x Se matrix, and the power factor of the doping material was improved through the reduction of high Cu defects to coordinate the three mutually coupled parameters. The ZT value of the WS 2 -doping Cu 2-x Se sample was eventually enhanced by 56% compared with pristine Cu 2-x Se, and up to ca. 1 at 823 K. • The samples of WS 2 -doping Cu 2-x Se were prepared. • WS 2 -doping Cu 2-x Se had low thermal conductivity and high power factor through the reduction of high carrier concentration. • The zT value of the WS 2 -doping Cu 2-x Se sample was eventually enhanced by 56% compared with pristine Cu 2-x Se, and up to ca. 1 at 823 K.