The Reduction of Thermal Conductivity in Cd and Sn Co-Doped Cu3SbSe4-based Composites with a Secondary-Phase CdSe

In this paper, we reported the enhanced thermoelectric properties of Cd and Sn dual-doped Cu3SbSe4-based material prepared by the vacuum melting combined with spark plasma sintering process. X-ray photoelectron spectroscopy studies revealed the presence of Cu+, Cd2+, Sb5+, Sn4+ and Se2− states of Cu, Cd, Sb, Sn and Se, respectively. All samples exhibited p-type conduction with carrier concentrations varying from 0.54 × 1018 to 46.42 × 1018 cm−3, while carrier mobility changes from 18.2 to 46.6 cm2 V−1 s−1 at room temperature. Cd doping at Cu sites in the Cu3SbSe4 can reduce the lattice thermal conductivity, while Sn doping at Sb sites is effective to adjust the carrier concentration. The further reduction in thermal conductivity is observed in Cd-Sn co-doped samples resulting from an accumulated effect combining point defects and the secondary-phase CdSe. Consequently, the maximum dimensionless figure of merit (ZT) value reaches 0.66 at 623 K for the Cu2.75Cd0.25Sb0.94Sn0.06Se4 sample, which is 190% larger than that of the intrinsic sample (ZT of 0.35). The findings provide an alternative strategy of boosting the carrier and phonon transports of the Cu3SbSe4, which is also a meaningful guidance to achieve high performance in other copper-based chalcogenides.