Thermoelectric properties and magnetoelectric coupling in dually doped Cu₂Sn_1−2xZn_xFe_xS₃

Thermoelectric properties of Cu₂Sn_1−2xZn_xFe_xS₃ (x = 0–0.1) doped with Zn and Fe as acceptor at Sn-site were investigated. With increased doping, the primary phase was observed to change from cation-ordered monoclinic phase to cation-disordered cubic and tetragonal phases. Favored by the growth of carrier concentration, and as well the enhanced DOS effective mass caused by Fe-doping, an optimal power factor ~ 12 μWcm⁻¹ K⁻² was obtained with x = 0.1 at 773 K. Meanwhile, the lattice thermal conductivity in the dual-doped samples was found to be further lower than that in the singly doped counterparts due to cations disordering and bond softening. These led to a maximal dimensionless figure of merit, ZT ~ 0.7 (x = 0.05), synergistically. Moreover, the magnetoelectronic coupling induced by Fe was observed to influence the carrier concentration sensitively, while little affecting the carrier’s mobility and effective mass.