Thermoelectric efficiency of nanoscale devices in the linear regime

Bevilacqua, Giuseppe; Grosso, Giuseppe; Menichetti, Guido; Parravicini, Giuseppe Pastori

doi:10.1103/physrevb.94.245419

Cited by 33 publications

(22 citation statements)

References 55 publications

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“…The evaluation of kinetic parameters is now straightforward and their analytic expression is reported in the lower part of table 1 in terms of the trigamma function z z n 1 It becomes now routine to investigate the thermoelectric transport properties. Following closely [39], in table 2 we report for sake of completeness the expressions of the electric and thermal conductances, of the Seebeck coefficient and the other transport parameters of interest, in terms of the kinetic coefficients K 0 , K 1, , and K 2 .…”

Section: Structure Of the Transmission Function And Analytic Evaluatimentioning

confidence: 99%

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

2018

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Coupled double quantum dots (c-2QD) connected to leads have been widely adopted as prototype model systems to verify interference effects on quantum transport at the nanoscale. We provide here an analytic study of the thermoelectric properties of c-2QD systems pierced by a uniform magnetic field. Fully analytic and easy-to-use expressions are derived for all the kinetic functionals of interest. Within the Green's function formalism, our results allow a simple inexpensive procedure for the theoretical description of the thermoelectric phenomena for different chemical potentials and temperatures of the reservoirs, different threading magnetic fluxes, dot energies and interdot interactions; moreover they provide an intuitive guide to parametrize the system Hamiltonian for the design of best performing realistic devices. We have found that the thermopower S can be enhanced by more than ten times and the figure of merit ZT by more than hundred times by the presence of a threading magnetic field. Most important, we show that the magnetic flux increases also the performance of the device under maximum power output conditions. It is worth noticing that in addition to the numerous papers dealing with two quantum dots tunnel-coupled to the leads and between themselves, also Coulomb-coupled quantum dots [24,25] have attracted increasing interest in the recent years [for a general perspective see [26]. This has been motivated by the advances in the fabrication of nano-devices, energy harvesting [22] with quantum dots, and the experimental possibility to taylor TE properties exploiting Coulomb interaction and the charge carriers correlation [27]. Moreover, in recent years parallel coupled quantum dots made of semiconductors with high spin-orbit interaction have proven promising systems to realize two-spin qubit in quantum information processing [28,29].Enhancing thermoelectric performance in linear regimes, requires maximization of the dimensionlesswhere σ is the electrical conductance, S the thermopower (Seebeck) coefficient, T is the temperature and κ=κ e +κ p is the thermal conductance (which includes electronic and lattice contributions). In the search of optimal thermoelectric response of the device, most important quantities are its maximum efficiency as thermoelectric generator, and the efficiency at the maximum of the output power.A crucial aspect both in the implementation of experimental methods [30], and in the evaluation of the thermoelectric response of bulk and nanostructured materials, is the wide parameters range to be explored simultaneously to determine its optimal functioning. In this context, the possibility of using analytic expressions for all the involved thermoelectric functions greatly simplifies the task. In the literature, the analytic treatment of the c-2QD is confined at sufficiently small temperatures by means of the Sommerfeld expansion, extended when necessary to fourth order in k B T in the evaluation of kinetic parameters [9]. In the case of Lorentzian shape of the transmission function, ...

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Section: Structure Of the Transmission Function And Analytic Evaluatimentioning

confidence: 99%

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

2018

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“…Most previous studies on the thermoelectric properties of QPCs focused on the linear response regime [ 11 , 12 , 21 , 22 , 23 , 24 ]. In this regime, the optimal performance of thermodynamic devices was extensively investigated, especially the efficiency at maximum power which is limited by the Curzon-Ahlborn efficiency [ 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Power, Efficiency and Fluctuations in a Quantum Point Contact as Steady-State Thermoelectric Heat Engine

Kheradsoud

Dashti

Misiorny

et al. 2019

Entropy

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The trade-off between large power output, high efficiency and small fluctuations in the operation of heat engines has recently received interest in the context of thermodynamic uncertainty relations (TURs). Here we provide a concrete illustration of this trade-off by theoretically investigating the operation of a quantum point contact (QPC) with an energy-dependent transmission function as a steady-state thermoelectric heat engine. As a starting point, we review and extend previous analysis of the power production and efficiency. Thereafter the power fluctuations and the bound jointly imposed on the power, efficiency and fluctuations by the TURs are analyzed as additional performance quantifiers. We allow for arbitrary smoothness of the transmission probability of the QPC, which exhibits a close to step-like dependence in energy, and consider both the linear and the non-linear regime of operation. It is found that for a broad range of parameters, the power production reaches nearly its theoretical maximum value, with efficiencies more than half of the Carnot efficiency and at the same time with rather small fluctuations. Moreover, we show that by demanding a non-zero power production, in the linear regime a stronger TUR can be formulated in terms of the thermoelectric figure of merit. Interestingly, this bound holds also in a wide parameter regime beyond linear response for our QPC device.

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“…Also, the phonon or lattice thermal conductance of low-dimensional systems is relatively small, which additionally contributes to the enhancement of thermoelectric efficiency [11,[22][23][24]. There has been a significant progress in investigating the linear and non-linear thermoelectric transport properties of a quantum dot (QD) coupled to the normal metallic/ferromagnetic reservoirs [16][17][18][19][20][21][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. For singlelevel QD coupled to normal reservoirs, the Coulomb interactions can enhance ZT by suppressing the electron thermal conductance and increasing the thermopower [19,31].…”

Section: Introductionmentioning

confidence: 99%

Non-equilibrium thermoelectric transport across normal metal-Quantum dot-Superconductor hybrid system within the Coulomb blockade regime

Verma

2021

Preprint

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A detailed investigation of the non-equilibrium steady-state electric and thermoelectric transport properties of a quantum dot coupled to the normal metallic and s-wave superconducting reservoirs (N-QD-S) are provided within the Coulomb blockade regime. Using non-equilibrium Keldysh Green's function formalism, initially, various model parameter dependence of thermoelectric transport properties are analysed within the linear response regime. It is observed that the single-particle tunnelling close to the superconducting gap edge can generate a relatively large thermopower and figure of merit. Moreover, the Andreev tunnelling plays a significant role in the suppression of thermopower and figure of merit within the gap region. Further, within the non-linear regime, we discuss two different situations, i.e., the finite voltage biasing between isothermal reservoirs and the finite thermal gradient in the context of thermoelectric heat engine. In the former case, it is shown that the sub-gap Andreev heat current can become finite beyond the linear response regime and play a vital role in asymmetric heat dissipation and thermal rectification effect for low voltage biasing. The rectification of heat current is enhanced for strong on-dot Coulomb interaction and at low background thermal energy. In the latter case, we study the variation of thermovoltage, thermopower, maximum power output, and corresponding efficiency with the applied thermal gradient. These results illustrate that hybrid superconductor-quantum dot nanostructures are a promising candidate for low-temperature thermal applications.

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Thermoelectric efficiency of nanoscale devices in the linear regime

Cited by 33 publications

References 55 publications

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

Power, Efficiency and Fluctuations in a Quantum Point Contact as Steady-State Thermoelectric Heat Engine

Non-equilibrium thermoelectric transport across normal metal-Quantum dot-Superconductor hybrid system within the Coulomb blockade regime

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