Modulation of electronic and thermal proprieties of TaMoS[formula omitted] by controlling the repulsive interaction between Ta dopant atoms

Abstract

We theoretically study the electronic and the thermal characteristics of Tantalum, Ta, doped Molybdenum disulfide, MoS2, using density functional theory. It has been shown that the MoS2 monolayer is not a good material for thermoelectric devices due to its relatively large band gap. We find that a Ta doped MoS2 forming a TaMoS2 monolayer can be useful for thermoelectric devices. The particular attention of this work is paid to the interaction effect between the Ta atoms in the MoS2 structure. We find that the interaction type is repulsive. It introduces an asymmetry in the density of states, DOS, reducing the band gap. In the presence of a strong repulsive interaction of Ta–Ta atoms, new states in the DOS around the Fermi energy are found leading to a reduction of the band gap. Consequently, a high Seebeck coefficient and figure of merit are seen over a wide range of energy around the Fermi energy. In contrast, a small reduction of the band gap and a vanishing degeneracy of the valence and the conduction bands are observed for the case of a weak Ta–Ta repulsive interaction leading to less promising thermoelectric properties.