Electronic structure and transport in CsBi$_4$Te$_6$

TL;DR

This paper investigates the electronic structure and transport properties of CsBi4Te6, a low-temperature thermoelectric material, using band structure calculations and semi-classic transport equations, highlighting the importance of the band gap and doping for optimizing thermoelectric performance.

Contribution

The study provides a detailed analysis of CsBi4Te6's band structure and transport properties, demonstrating the necessity of a specific band gap for accurate modeling and predicting potential for improved thermoelectric performance with doping.

Findings

A band gap of 0.08 eV is needed for quantitative agreement with experiments.

The p-type sample has near-optimal carrier concentration.

n-type doping could surpass p-type thermoelectric performance.

Abstract

The band structure of the novel low-temperature thermoelectric material, \CBT, is calculated and analyzed using the semi-classic 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. 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.