Co-regulation of the copper vacancy concentration and point defects leading to the enhanced thermoelectric performance of Cu(3)In(5)Te(9)-based chalcogenides

Copper vacancy concentration (V(c)) in ternary Cu–In–Te chalcogenides is an important factor to engineer carrier concentration (n(H)) and thermoelectric performance. However, it is not sufficient to regulate the phonon scattering in the Cu(3)In(5)Te(9)-based chalcogenides. In this work we manipulate the V(c) value and point defects simultaneously through addition of Cu along with Ga substitution for In in Cu(3)In(5)Te(9), and thereby increase the carrier concentration and reduce the lattice thermal conductivity. This strategy finally enables us to achieve ∼60% enhancement of the TE figure of merit (ZT) at V(c) = 0.078 compared with the pristine Cu(3)In(5)Te(9). It is also used as guidance to achieve the high TE performance of the ternary chalcogenides.