Controling Nonlinear Thermoelectricity of a Quantum Dot by Quantum Interference

We theoretically study how one can control and enhance nanoscale nonlinear thermoelectricity by regulating quantum interference. We take the configuration of a quantum-dot interferometer (a quantum dot embedded in the ring geometry), which can also represent a model of a single-molecule junction. One can adjust quantum coherence by modifying direct conducting channels between the leads (Fano's effect). Within the linear response theory, such Fano resonances have been suggested to enhance drastically the thermoelectric figure of merit, which reaches an order-of-unity value even for a non-thermoelectric material. We revisit the idea by examining the efficiency and the output power in the nonlinear response regime. Based on the microscopic model and nonequilibrium Green function techniques, we can incorporate the strong correlation on the dot and charge-blocking effect. We show how the presence of direct conducting channels can greatly enhance nonlinear thermoelectric performance, even when the resonance width is much larger than temperature.