Electronic structure and transport in the low-temperature thermoelectric $\mathrm{Cs}{\mathrm{Bi}}_{4}{\mathrm{Te}}_{6}$: Semiclassical transport equations

Electronic structure and transport in the low-temperature thermoelectric $Cs {Bi}_{4} {Te}_{6}$ : Semiclassical transport equations

Lars Lykke, Bo B. Iversen, and Georg K. H. Madsen

Phys. Rev. B 73, 195121 – Published 24 May 2006

Abstract

The band structure of the low-temperature thermoelectric material, $Cs {Bi}_{4} {Te}_{6}$ , is calculated and analyzed using the semiclassic transport equations. It is shown that to obtain a quantitative agreement with measured transport properties, a band gap of $0.08 eV$ must be enforced. A gap in reasonable agreement with experiment was obtained using the generalized gradient functional of Engel and Vosko [E. Engel and S. H. Vosko, Phys. Rev. B 47, 13164 (1993)]. We found that the experimental $p$ -type sample has a carrier concentration close to optimal. Furthermore, the conduction bands have a form equally well suited for thermoelectric properties and we predict that an optimally doped $n$ -type compound could have thermoelectric properties exceeding those of the $p$ type.