Electron Transport Engineering by Nanostructures for Efficient Thermoelectrics

Abstract

We theoretically investigate nanoscale structures such as nanoparticles embedded in bulk materials as a means of improving the thermoelectric energy conversion efficiency. We focus on the impact of such nanostructures on the electron transport in the host material, and discuss the enhancement of the thermoelectric power factor and thus the figure of merit. Nanostructures embedded in thermoelectric materials can create potential variations at the nanoscale due to the hetero-interfaces, which can alter the transport of charge carriers in the host material to enhance the Seebeck coefficient and the power factor. The energy-dependent electron scattering times induced by nanoparticles are calculated using the partial wave method. Thermoelectric transport properties are then calculated based on the linearized Boltzmann transport theory with the relaxation time approximation for various thermoelectric materials such as ErAs:InGaAs, PbTe, and Mg2Si. The effects of different kinds of nanoparticles including single-phase ionized metallic nanoparticles and core–shell nanoparticles embedded in semiconductors are investigated in these semiconductors. Finally the electron energy filtering scheme is discussed to further enhance the thermoelectric energy conversion efficiency.