Ultralow Thermal Conductivity and Enhanced Figure of Merit for CuSbSe₂ via Cd-Doping

Thermoelectric properties of CuSb1–xCdxSe2 (x = 0–0.08) compounds, prepared by vacuum melting, were studied at temperatures of 300–675 K. The results indicate that Cd doping causes both remarkable increase in the Seebeck coefficient and drastic drop of lattice thermal conductivity. The enhancement of thermopower originates mainly from increase of electronic density of states, while the drop of lattice thermal conductivity can be ascribed to enhanced phonon scattering by introduced impurity (dopant) atoms. As a consequence, thermoelectric figure of merit ZT is improved with a maximum ZT = 0.55 (at 675 K) being reached for CuSb0.98Cd0.02Se2, which is around 2.2-fold higher than that of the CuSbSe2 pristine compound. Our results indicate that Cd substitution is a feasible way to improve thermoelectric performance of the CuSbSe2-based system.