Theoretical study of the thermoelectric properties of SiGe nanotubes

TL;DR

This study investigates the thermoelectric properties of SiGe nanotubes using computational methods, revealing their potential for high thermoelectric efficiency with ZT values up to 5.4, influenced by chirality and temperature.

Contribution

It provides a theoretical analysis of SiGe nanotubes' thermoelectric performance, highlighting their high ZT and the effects of chirality and temperature, which was not previously explored.

Findings

Seebeck coefficients are larger than bulk materials

ZT values can reach 5.4 at 400 K

Lattice thermal conductivity is reduced by phonon boundary and alloy scattering

Abstract

The thermoelectric properties of two typical SiGe nanotubes are investigated using a combination of density functional theory, Boltzmann transport theory, and molecular dynamics simulations. Unlike carbon nanotubes, these SiGe nanotubes tend to have gear-like geometry, and both the (6, 6) and (10, 0) tubes are semiconducting with direct band gaps. The calculated Seebeck coefficients as well as the relaxation time of these SiGe nanotubes are significantly larger than those of bulk thermoelectric materials. Together with smaller lattice thermal conductivity caused by phonon boundary and alloy scattering, these SiGe nanotubes can exhibit very good thermoelectric performance. Moreover, there are strong chirality and temperature dependence of the ZT values, which can be optimized to 4.9 at room temperature and further enhanced to 5.4 at 400 K for the armchair (6, 6) tube.