Screening for new thermoelectric material: A semiconducting TaS₃ with nanoporous structure

Highlights

• A new semiconducting TaS₃ with the space group C2/m is discovered by the CALYPSO swarm-intelligence optimization method.

• C2/m-TaS₃ exhibits anisotropic multivalley band dispersions and the low lattice thermal conductivity of 2.13 W/mK at 800 K.

• The calculated figure of merit ZT can reach up to 1.68 and 1.57 at 800 K for p- and n-type TaS₃, respectively.

Abstract

Transition-metal sulfides, such as 1T- and 2H-TaS₂, are attracting considerable interest in modern condensed matter physics for their diverse behaviors of the Mott state, peculiar charge-density-wave phase and superconductivity. The intrinsically low thermal conductivities along the cross-plane direction can advantage the potential high thermoelectric performance; yet, their insignificant power factors severely hampered the practical applications as thermoelectric devices. In this perspective, we herein present a new semiconducting phase in TaS₃ with the space group C2/m predicted by the swarm-intelligence structure-searching method. The C2/m-TaS₃ phase exhibits anisotropic multivalley band dispersions, which is beneficial for electronic transport. Meanwhile, the unique structure within nanopores leads to strong anharmonic scattering, significantly reducing the lattice thermal conductivity. As a result, the calculated figure of merit ZT can reach up to 1.68 and 1.57 at 800 K for p- and n-type, respectively that is comparable with conventional thermoelectric materials (e.g. PbTe, Bi₂Te₃). Therefore, our calculation reveals that the C2/m-TaS₃ phase can be a potential high-performance candidate as non-toxic and eco-friendly thermoelectrics, and will stimulate further experimental exploration for understanding and tailoring thermoelectric capability in related transition-metal sulfides.