Thermoelectric transport in strongly correlated quantum dot nanocomposites

Abstract

We investigate the thermoelectric transport properties (electrical conductivity, Seebeck coefficient, power factor, and thermoelectric figure of merit) in strongly correlated quantum dot nanocomposites at low temperature (77 K) by using the dynamical mean-field theory and the Kubo formula. The periodic Anderson model is applied to describe the strongly correlated quantum dot nanocomposites with tunable parameters such as the size of quantum dots and the electron occupation number. The electron occupation number can be controlled by the doping concentration in the both matrix and quantum dots, the size of quantum dots, and the interdot spacing. These parameters control the transition between $n$-type like behavior (with negative Seebeck coefficient) and $p$-type like behavior (with positive Seebeck coefficient) of strongly correlated quantum dot nanocomposites. Large Seebeck coefficient up to $260\text{ }\ensuremath{\mu}\text{V}/\text{K}$ due to the asymmetry of the electron bands with sharp electron density of states can be obtained in the strongly correlated quantum dot nanocomposites, along with moderate electrical conductivity values in the order of ${10}^{5}/\ensuremath{\Omega}\text{ }\text{m}$. This results in optimal power factor about $78\text{ }\ensuremath{\mu}\text{W}/\text{cm}\text{ }{\text{K}}^{2}$ and optimal figure of merit $(ZT)$ over 0.55 which is much larger than the value of the state-of-the-art low-temperature thermoelectric materials. This study shows that high efficiency thermoelectric materials at low temperature can be obtained in strongly correlated quantum dot nanocomposites.