Resonant carrier scattering by core-shell nanoparticles for thermoelectric power factor enhancement

We theoretically investigate the use of energetically sharp resonances of core-shell nanoparticles embedded in semiconductors to selectively scatter carriers and thereby enhance the thermoelectric power factor and figure of merit. Appropriate selection of materials for the core-shell band structure can lead to the formation of quasi-bound states inside the nanoparticles, which strongly scatter carriers near these energy levels, making sharp features in the energy-dependent electron relaxation time. We find that the power factor of PbTe at 80K is enhanced by more than 80% when core-shell nanoparticles of 3 nm core diameter and 1.5 nm shell width are introduced with density 1 x 10(18) cm(-3). (C) 2012 American Institute of Physics. [doi: 10.1063/1.3673615]