Nanowires with dislocations for ultralow lattice thermal conductivity

Abstract

Nanostructures grown by screw dislocations have been successfully synthesized in a range of materials, including thermoelectric materials, but the impact of these extended crystallographic defects on thermal properties of these nanostructures is not known. We investigate thermal transport in PbSe and SiGe nanowires storing screw dislocations via equilibrium molecular dynamics simulations. The inherent one dimensionality and the combined presence of a reconstructed surface and dislocation yield ultralow thermal conductivity values. Our simulations suggest that the large dislocation strain field in nanowires may play a key role in suppressing the thermal conductivity of thermoelectric nanomaterials to increase their thermoelectric figure of merit.