Engineering Electronic and Thermal Properties of Thermoelectric Semiconductors
Prof. G. Jeffrey Snyder
Northwestern University
Thermoelectric (TE) energy conversion is widely studied for its potential to produce electricity from waste heat or provide cooling without the use of harmful refrigerants. Higher performance is found in complex semiconductors that have a high number of charge carriers like a metal, high mobility like a crystalline semiconductor but low thermal conductivity like a glass.
The quality of a thermoelectric material is proportional to the density-of-states weighted mobility, µW, and inversely proportional to the thermal conductivity due to atom vibrations, κL. The weighted mobility, µW, is related to the mobility measured by the Hall effect and density of electronic states measured by the Seebeck effective mass m*. This can be used to identify electron scattering mechanisms and complex band structures in metals and semiconductors for a variety of applications.
The phonon or lattice thermal conductivity κL, due to the atomic vibrations, depends on the phonon speed and scattering which is studied using phonon band structures. Strategies to find materials with low phonon speed and high scattering rates can be used to engineer good thermoelectrics but also thermal barrier coatings and high power electronics.
Hosted by Prof. Assaf