A First-Principles Theoretical Study on the Thermoelectric Properties of the Compound Cu5AlSn2S8

Abstract

A new compound of Cu5AlSn2S8, which contained earth-abundant and environment-friendly elements and had a diamond-like crystal structure, was designed, and its electronic structure and thermoelectric transport properties from 300 K to 700 K were investigated by first-principles calculations, Boltzmann transport equations, and a modified Slack’s model. The largest power factors of Cu5AlSn2S8 at 700 K were 47.5 × 1010 W m−1 K−2 s−1 and 14.7 × 1010 W m−1 K−2 s−1 for p- and n-type semiconductors, respectively. The lattice thermal conductivity of Cu5AlSn2S8 was calculated with its shear modulus and isothermal bulk modulus, which were also obtained by first-principles calculations. The lattice thermal conductivity was 0.9–2.2 W m−1 K−1 from 300 K to 700 K, relatively low among thermoelectric compounds. This theoretical study showed that Cu5AlSn2S8 could be a potential thermoelectric material.