Nonmonotonic thermoelectric currents and energy harvesting in interacting double quantum dots

A theoretical study of the thermoelectric current and energy harvesting in an interacting double-quantum-dot system, connected to reservoirs held at different chemical potentials and temperatures, is presented. Using a rate-equation approach, the current is evaluated for different energetic configurations of the double quantum dot. We discuss in detail the current-temperature gradient relations (the thermoelectric analog to current-voltage relations) and demonstrate that, due to interactions, the current is nonmonotonically dependent on thermal bias. This interaction-induced nonmonotonicity influences the possibility of harvesting thermal energy from the double quantum dot, and it is shown that in some configurations, energy cannot be harvested at all. We analyze the conditions under which energy can, indeed, be harvested and converted to useful electrical power and the optimal conditions for thermoelectric energy conversion.