We present a model describing the carrier conductivity and Seebeck coefficient of thermoelectric nanocomposite materials consisting of granular regions. The model is successfully applied to explain relevant experimental data for PbTe nanocomposites. A key factor is the grain potential boundary scattering mechanism. Other mechanisms, such as carrier-acoustic phonon, carrier-nonpolar optical phonon, and carrier-ionized impurities scattering are also included. Our calculations reveal that by changing the physical characteristics of the grains, such as potential barrier height, width, and distance between the grains, one can increase the mean energy per carrier in order to obtain an optimum power factor for improved thermoelectric performance. The model can be applied to other nanocomposites by incorporating the appropriate electronic structure parameters.

• Received 17 September 2008

DOI:https://doi.org/10.1103/PhysRevB.79.205302