Excellent Thermoelectric Performance of the Metal Sulfide CuTaS₃

We use the ab initio scattering and transport method for computing the electronic transport properties of the ternary compound CuTaS₃. Both the valence and conduction band edges show band convergence, resulting in high p- and n-type thermoelectric power factors, respectively. We find that polar optical phonon scattering and ionized impurity scattering significantly reduce the carrier mobilities. The lattice thermal conductivity is low due to low phonon group velocities. The combination of the high power factors with the low lattice thermal conductivity leads to high p- and n-type thermoelectric figures of merit.