Theoretical Aspects of the Study on the Thermoelectric Properties of Pnictogen-Dichalcogenide Layered Compounds

摘要

Recent experimental studies revealed that BiCh(2) (Ch = S, Se) layered compounds, which have been well known as superconductors, also exhibit high thermoelectric performance. We review theoretical investigations on the thermoelectric properties of PnCh(2) (Pn = Bi, Sb, As) layered compounds. Their electronic structure shows quasi-one-dimensionality, which is favorable for realizing high power factor. This quasi-one-dimensionality originates from the anisotropy of the p(x,y) orbitals on the PnCh(2) square lattice. First-principles calculation suggests that atomic substitution can enhance the one-dimensionality, and thus the power factor. Another important aspect is the lattice instability, which can result in the strong anharmonicity of phonons and the low lattice thermal conductivity.