Thermoelectric properties of ternary chalcogenides and oxides from first principles calculations*

Several ternary chalcogenide compounds have been reported as high-performance or promising thermoelectric materials. Previous works have shown that AgBiSe₂ and TlSbTe₂ have high ZT values of 1.5 and 0.87, respectively [1,2]. Even though there are many other possible candidates of ternary chalcogenides, thermoelectric properties of most of them have not been reported.
In the present study, in order to narrow down promising candidates, we analyze the thermoelectric properties of 20 chalcogenide and oxide compounds represented as ABCh₂ (Ch = O, S, Se, Te) by using first-principles calculation and Boltzmann equation. We find that the power factor of the compounds composed of A = Li, Na, B = Ga, In, and Ch = O are far higher than those of other compounds, which originates from the favorable electronic structure possessing quasi-one-dimensionality and multi valley degeneracy. It is also revealed that we can control the electrical conductivity along the c-axis by the substitution of A atom.

[1] C. Xiao et al., J. Am. Chem. Soc. 134, 18460 (2013).
[2] K. Kurosaki et al., J. Alloy. Compd. 376, 43 (2004).