Co-regulation of the copper vacancy concentration and point defects leading to the enhanced thermoelectric performance of Cu3In5Te9-based chalcogenides

Abstract

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 Cu₃In₅Te₉-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 Cu₃In₅Te₉, 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 Cu₃In₅Te₉. It is also used as guidance to achieve the high TE performance of the ternary chalcogenides.