High pressure synthesis and thermoelectric performances of Cu2Se compounds

The Cu2Se samples were synthesized by high pressure directly at room temperature in several minutes. The composition evolution under high pressure demonstrates that the critical conditions to synthesize Cu2Se are the pressure of 1 GPa and the reaction time of 5 min. The synthetic pressure can effectively tune the morphology, carrier concentration and the electrical transport properties. The low lattice thermal conductivity less than 0.5 Wm−1 K−1 is obtained because of the intrinsic superionic character and the microstructures by high pressure including abundant micropores and lattice defects. A maximum zT of 0.92 at 783 K is achieved for Cu2Se synthesized at 1 GPa. This work indicates the potentiality of high pressure technique to further enhance the thermoelectric properties of Cu2Se materials.