Thermoelectric properties of materials with nontrivial electronic topology

Materials with good thermoelectric (TE) properties such as Bi2Te3 and SnTe have recently come to be known as topological insulators (TIs). It is fundamentally interesting to explore if other materials with non-trivial electronic topology may also exhibit good TE properties. In this work, we use first-principles density functional theoretical calculations to determine and analyze the electronic thermoelectric properties (Seebeck coefficient (S), electrical conductivity (sigma) and thermoelectric power factor (P)) of topological insulators (beta-As2Te3, BiTeCl, and PbTe), a topological Dirac semimetal (Na3Bi) and a Weyl semimetal (TaAs) and semimetallic YPtBi, belonging to different symmetry and topological classes. We find that the multiple sub-band structure, the small band gap of topological insulators, and their vicinity to a metallic state associated with an electronic topological transition (ETT) are responsible for their superior TE performance. In addition, sensitivity of their electronic structure to strain makes their thermoelectric properties highly tunable. We predict that TaAs is a promising TE for experimental exploration, and propose that the thermoelectric modulators based on TIs such as SnTe and PbTe will be more efficient under mechanical load.