THERMOELECTRIC TRANSPORT IN Sb2Te3/Bi2Te3 QUANTUM DOT NANOCOMPOSITES

We investigate the thermoelectric transport properties of Sb2Te3/Bi2Te3 quantum dot nanocomposites with spherical Sb2Te3 quantum dots arrays embedded in Bi2Te3 matrix through a two-channel transport model. In this model, the transport of quantum-confined electrons through the hopping mechanism is studied by tight-binding model together with Kubo formula and Green's function method. The formation of minibands due to the quantum confinement and the phonon-bottleneck effect on carrier-phonon scattering are considered. The transport of bulk-like electrons is studied by Boltzmann-transport-equation-based model. We consider the intrinsic carrier scatterings as well as the carrier-interface scattering of these bulk-like electrons. Thermoelectric transport properties are studied with different quantum dot sizes, inter-dot distances, doping concentrations, and temperatures. We find that electrical conductivity and Seebeck coefficient can be enhanced simultaneously in Sb2Te3/Bi2Te3 quantum dot nanocomposites because of the formation of minibands and the phonon-bottleneck effect on carrier-phonon scattering. Our results could shed some light on the design of high-efficiency thermoelectric materials.