Thermoelectric properties of Cu3SbSe3 with intrinsically ultralow lattice thermal conductivity

Abstract

We report the synthesis, characterization and evaluation of the thermoelectric properties of Cu₃SbSe₃ with a view to explore its utility as an useful thermoelectric material due to its intrinsically low thermal conductivity. Cu₃SbSe₃ was synthesized employing a solid state reaction process followed by spark plasma sintering, and the synthesized material was extensively characterized for its phase, composition and structure, which suggested formation of a single-phase. The measured electrical transport properties of Cu₃SbSe₃ indicated p-type conduction in this material. The electrical transport behavior agrees well with that predicted theoretically using first-principle density-functional theory calculations, employing generalized gradient approximation. The measured thermal conductivity was found to be 0.26 W m⁻¹ K⁻¹ at 550 K, which is the lowest reported thus far for Cu₃SbSe₃ and is among the lowest for state-of-the-art thermoelectric materials. Despite its ultralow thermal conductivity coupled with a moderate Seebeck coefficient, the calculated value of its thermoelectric figure-of-merit was found to be exceptionally low (<0.1), which was primarily attributed to its low electrical conductivity. Nevertheless, it is argued that Cu₃SbSe₃, due its environmentally-friendly constituent elements, ultralow thermal conductivity and moderate thermopower, could be a potentially useful thermoelectric material as the power factor can be favorably tailored by tuning the carrier concentration using suitable metallic dopants.