The reduction of thermal conductivity in Cd and Sn co-doped Cu 3 SbSe 4 -based composites with a secondary-phase CdSe

In this paper, we reported the enhanced thermoelectric properties of Cd and Sn dual-doped Cu 3 SbSe 4 -based material prepared by the vacuum melting combined with spark plasma sintering process. X-ray photoelectron spectroscopy studies revealed the presence of Cu + , Cd 2+ , Sb 5+ , Sn 4+ and Se 2− states of Cu, Cd, Sb, Sn and Se, respectively. All samples exhibited p -type conduction with carrier concentrations varying from 0.54 × 10 18 to 46.42 × 10 18 cm −3 , while carrier mobility changes from 18.2 to 46.6 cm 2 V −1 s −1 at room temperature. Cd doping at Cu sites in the Cu 3 SbSe 4 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 Cu 2.75 Cd 0.25 Sb 0.94 Sn 0.06 Se 4 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 Cu 3 SbSe 4 , which is also a meaningful guidance to achieve high performance in other copper-based chalcogenides.