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

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.