Potential thermoelectric material Tl3XS4 (X = V, Nb, Ta) with ultralow lattice thermal conductivity.

Abstract

The demand for sustainable energy solutions has driven intensive research into advanced thermoelectric (TE) materials, to harness waste heat for efficient power generation. Recently, several studies have revealed that Tl3VS4 possesses an ultralow lattice thermal conductivity, despite its simple body-centered cubic lattice structure. This paper focuses on the TE properties of Tl3XS4 (X = V, Nb, Ta) compounds through a systematic exploration utilizing first-principles calculations and semiclassical Boltzmann transport theory. The results of the AIMD simulation and phonon calculation reveal the excellent dynamic stability and thermal stability of Tl3XS4 at 300, 500, and 700 K. Moreover, we find that the Tl3XS4 compounds present ultralow lattice thermal conductivity (<0.5 W m-1 K-1 at 300 K), and the nanostructure strategy is effective. Based on the outstanding Seebeck coefficient and ultralow lattice thermal conductivity, the optimal ZT values of Tl3VS4, Tl3NbS4, and Tl3TaS4 at 300 K are determined to be 1.17 (p-type), 0.84 (n-type), and 0.65 (p-type), respectively. Additionally, at each considered temperature, the maximum ZT values of p-type (n-type) Tl3XS4 follow the order: Tl3VS4 > Tl3NbS4 > Tl3TaS4 (Tl3NbS4 > Tl3VS4 > Tl3TaS4). Our results demonstrate that Tl3XS4 (X = V, Nb, Ta) compounds are promising thermoelectric materials. This exhaustive research enhanced our nuanced comprehension of the electronic, dynamic, and thermoelectric attributes of Tl3XS4 (X = V, Nb, Ta), thereby offering valuable insights into the TE field.