33^rd World Nano Conference

Biography

Biography: Dhritiman Chakraborty

Abstract

Nanostructuring of thermoelectric materials is a method with great potential for improved and novel thermoelectric materials with ultra-low thermal conductivities and improved power factors, thereby enhanced thermoelectric efficiencies. Nanostructuring introduces scattering of phonons of various wavelengths and hence reduces phonon transport throughout the spectrum–yielding ultra-low thermal conductivities. Introducing disorder at the nanoscale reduces thermal conductivity even further. However, there are very few models that accurately determine how disorder reduces thermal conductivity in nanostructured materials.

In this work, we provide simplified models that accurately describe the effects of disorder and porosity at the nanoscale by solving the Boltzmann transport equation for phonons using the Monte Carlo method in Si-based nanostructures with a large degree of disorder. We examine nanostructures with nanocrystalline grain structures in addition to nanopores, both in an ordered and highly randomized fashion. Such materials have demonstrated experimentally thermal conductivities even below the amorphous limit. We extract analytical models that capture quantitatively the thermal conductivity in nanostructures that include a combination of nanograins and nanopores, in disordered nanostructures. Finally, we compare our models with predictions by Mattheissen’s rule and find good agreement.