Enhancement of thermoelectric properties by atomic-scale percolation in digenite CuxS

Abstract

Atomic-scale percolation phenomena of electric and thermal conductivity were found in digenite Cu_xS. Copper ions are randomly located between the closely packed sulphur ions and jump to another position via unoccupied interstices. Near the percolation threshold value (f_c ∼ 0.3) in the conductive region, a 60% enhancement of ZT value can be obtained. This indicates that the percolation phenomena can provide a new strategy to optimize the properties of thermoelectric materials, especially for quasi disordered materials.