arXiv subjects

Jincheng Lu

Publications and source records attributed to Jincheng Lu.

23 records · Page 2Linked to original sources

arXiv2019

Optimal efficiency and power and their trade-off in three-terminal quantum thermoelectric engines with two output electric currents

We establish a theory of optimal efficiency and power for three-terminal thermoelectric engines which have two independent output electric currents and one input heat current. This set-up goes beyond the conventional heat engines with only one output electric current. For such a set-up, we derive the optimal efficiency and power and their trade-off for three-terminal heat engines with and without time-reversal symmetry. The formalism goes beyond the known optimal efficiency and power for systems with or without time-reversal symmetry, showing interesting features that have not been revealed before. A concrete example of quantum-dot heat engine is studied to show that the current set-up can have much improved efficiency and power compared with previous set-ups with only one output electric current. Our analytical results also apply for thermoelectric heat engines with multiple output electric currents, providing an alternative scheme toward future high-performance thermoelectric materials.

cond-mat.mes-hall↗

arXiv2019

Enhancing thermophotovoltaic performance using graphene-BN-InSb near-field heterostructures

Graphene---hexagonal-boron-nitride---InSb near-field structures are designed and optimized to enhance the output power and energy efficiency of the thermophotovoltaic systems working in the temperature range of common industrial waste heat, $400~\rm K \sim 800~\rm K$, which is also the working temperature range for conventional thermoelectric devices. We show that the optimal output electric power can reach $3.5\times10^{4} \rm\ W/\rm m^2$ for the system with a graphene---hexagonal-boron-nitride heterostructure emitter and a graphene-covered InSb cell, whereas the best efficiency is achieved by the system with the heterostructure emitter and an uncovered InSb cell (reaching to $27\%$ of the Carnot efficiency). These results show that the performances of near-field thermophotovoltaic systems can be comparable with or even superior than the state-of-art thermoelectric devices. The underlying physics for the significant enhancement of the thermophotovoltaic performance is understood as due to the resonant coupling between the emitter and the cell, where the surface plasmons in graphene and surface phonon-polaritons in boron-nitride play important roles. Our study provides a stepping stone for future high-performance thermophotovoltaic systems.

physics.app-ph↗

arXiv2018

Quantum-dot circuit-QED thermoelectric diodes and transistors

Recent breakthroughs in quantum-dot circuit-quantum-electrodynamics (circuit-QED) systems are important both from a fundamental perspective and from the point of view of quantum photonic devices. However, understanding the applications of such setups as potential thermoelectric diodes and transistors has been missing. In this paper, via the Keldysh nonequilibrium Green's function approach, we show that cavity-coupled double quantum-dots can serve as excellent quantum thermoelectric diodes and transistors. Using an enhanced perturbation approach based on polaron-transformations, we find non-monotonic dependences of thermoelectric transport properties on the electron-photon interaction. Strong light-matter interaction leads to pronounced rectification effects for both charge and heat, as well as thermal transistor effects in the linear transport regime, which opens up a cutting-edge frontier for quantum thermoelectric devices.

cond-mat.mes-hall↗

arXiv2018

Nonlinear effects for three-terminal heat engine and refrigerator

The three-terminal heat device consisting of a cavity and coupled to a heat bath is established. By tuning the temperatures of the electrodes and the phonon bath, the device can function as a heat engine or a refrigerator. We study the characteristic performance in the linear and nonlinear regime for both setups. It is our focus here to analyze how the efficiency of the heat engine and coefficient of performance of the refrigerator are affected by the nonlinear transport. With such considerations, the maximum efficiency and power are then optimized for various energy levels, temperatures and other parameters.

cond-mat.mes-hall↗

arXiv2017

Thermoelectric Cooperative Effect in Three-Terminal Elastic Transport through a Quantum Dot

The energy efficiency and power of a three-terminal thermoelectric nanodevice are studied by considering elastic tunneling through a single quantum dot. Facilitated by the three-terminal geometry, the nanodevice is able to generate simultaneously two electrical powers by utilizing only one temperature bias. These two electrical powers can add up constructively or destructively, depending on their signs. It is demonstrated that the constructive addition leads to the enhancement of both energy efficiency and output power for various system parameters. In fact, such enhancement, dubbed as thermoelectric cooperative effect, can lead to maximum efficiency and power no less than when only one of the electrical power is harvested.

cond-mat.mes-hall↗