Thermoelectric effects of a laterally coupled double-quantum-dot structure

We investigate the thermoelectric properties of a laterally coupled double-quantum-dot structure. For this structure, a one-dimensional quantum dot (QD) chain between two leads forms a main channel for electron transmission, and each QD in the chain laterally couples to an additional QD. It is found that at low temperature, similar insulating bands emerge around the antiresonant points in the electronic and thermal conductance spectra. And, the edges of the insulating bands become steep rapidly with the increase of QD numbers. What’s interesting is that striking thermoelectric effect exists in the energy region where the insulating bands appear. Furthermore, with the formation of the insulation bands, the magnitude of the Seebeck coefficient becomes stable, whereas the thermoelectric efficiency is increased. By plotting the Lorentz number spectrum, we observe that in such a structure, the Lorentz number strongly violates the Wiedemann-Franz law in the insulating-band region with its maximum at the point of antiresonance. When weak intradot Coulomb interaction is taken into account, the weakened thermoelectric effect can still be improved with the increase of QD numbers.