2019/02/28 by Samuel Foster, Foster, Samuel, Mischa Thesberg +3
Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Thermal properties of materials #Advanced Thermodynamics and Statistical Mechanics
paper · pdf · doi:10.48550/arxiv.1903.00357
Some of the most promising candidates for next generation thermoelectrics are\nnanocomposites due to their low thermal conductivities that result from phonon\nscattering on the boundaries of the various material phases. However, in order\nto maximize the figure of merit ZT, it is important to understand the impact of\nsuch features on the thermoelectric power factor. In this work we consider the\neffect that nanoinclusions and voids have on the electronic and thermoelectric\ncoefficients of two dimensional geometries using the fully quantum mechanical\nNon Equilibrium Greens Function method. This method combines in a unified\napproach the details of geometry, electron phonon interactions, quantisation,\ntunnelling, and the ballistic to diffusive nature of transport. We show that as\nlong as the barrier height is low nanoinclusions can have a positive impact on\nthe Seebeck coefficient and the power factor is not severely impacted by a\nreduction in conductance. The power factor is also shown to be approximately\nindependent of nanoinclusion and void density in the ballistic case. On the\nother hand, in the presence of phonon scattering voids degrade the power factor\nand their influence increases with density.\n