Thermoelectric properties of a chain of coupled quantum dots embedded in a nanowire

Abstract

The thermoelectric properties of a chain of coupled quantum dots (CCQDs) connected to metallic electrodes are theoretically investigated in the Coulomb blockade regime. An extended Hubbard model is employed to simulate the CCQD system consisted of finite number of quantum dots (QDs). The charge and heat currents are calculated in the framework of Keldysh Green's function technique. The authors obtained a closed-form Landauer expression for the transmission coefficient of the CCQD system with arbitrary number of QDs by using the method beyond mean-field theory. The electrical conductance (Ge), Seebeck coefficient (S), thermal conductance, and figure of merit (ZT) are numerically calculated and analyzed in the linear response regime. In the Coulomb blockade regime thermal conductance is dominated by phonons, the optimization of ZT is determined by the power factor (PF=S2Ge). The authors find that the optimization of ZT value favors the conditions of QD energy levels above the Fermi level of electrodes and QDs with small energy level fluctuations. The optimal ZT values are seriously suppressed by the inelastic scattering of electrons.