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The thermoelectric conversion efficiency problem: Insights from the electron gas thermodynamics close to a phase transition
by I. Khomchenko, A. Ryzhov, F. Maculewicz, F. Kurth, R. Hühne, A. Golombek, M. Schleberger, C. Goupil, Ph. Lecoeur, A. Böhmer, G. Benenti, G. Schierning, H. Ouerdane
Submission summary
| Authors (as registered SciPost users): | Giuliano Benenti · Ilia Khomchenko · Henni Ouerdane · Gabi Schierning |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2110.11000v3 (pdf) |
| Date submitted: | 2023-07-25 10:44 |
| Submitted by: | Ouerdane, Henni |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Experimental |
Abstract
The bottleneck in modern thermoelectric power generation and cooling is the low energy conversion efficiency of thermoelectric materials. The detrimental effects of lattice phonons on performance can be mitigated, but achieving a high thermoelectric power factor remains a major problem because the Seebeck coefficient and electrical conductivity cannot be jointly increased. The conducting electron gas in thermoelectric materials is the actual working fluid that performs the energy conversion, so its properties determine the maximum efficiency that can theoretically be achieved. By relating the thermoelastic properties of the electronic working fluid to its transport properties (considering noninteracting electron systems), we show why the performance of conventional semiconductor materials is doomed to remain low. Analyzing the temperature dependence of the power factor theoretically in 2D systems and experimentally in a thin film, we find that in the fluctuation regimes of an electronic phase transition, the thermoelectric power factor can significantly increase owing to the increased compressibility of the electron gas. We also calculate the ideal thermoelectric conversion efficiency in noninteracting electron systems across a wide temperature range neglecting phonon effects and dissipative coupling to the heat source and sink. Our results show that driving the electronic system to the vicinity of a phase transition can indeed be an innovative route to strong performance enhancement, but at the cost of an extremely narrow temperature range for the use of such materials, which in turn precludes potential development for the desired wide range of thermoelectric energy conversion applications.
Author comments upon resubmission
On behalf of all coauthors, I thank you for your time reviewing our work and the very useful remarks and criticism.
We believe that our manuscript contains much interesting physics about a very challenging problem, and we are grateful for an opportunity to revise our manuscript and resubmit it.
The work is essentially of theoretical nature but we also complemented it with experimental data to make a case for more efforts and attention on the problem of the electron gas fluctuating regimes in thermoelectricity. The manuscript should thus not be viewed as a "theory vs. experiment" report but rather as a work that provides theoretical grounds and experimental data to further explore fluctuating regimes near phase transition and their influence on thermoelectric energy conversion.
Our reply to the Referees' report is provided separately, just below their reports.
Sincerely,
Dr. Henni Ouerdane
List of changes
The main new change in our work is the discussion on nematic fluctuations to describe the experimental data.
To address the points raised by the Referees we revised our manuscript as follows.
1/ We added text and references on nematic fluctuations in the Introduction;
2/ We clarified the specific aims of our work in the Introduction;
3/ We expanded the Section 2 - Theory, to introduce and explain all the basic ingredients of our thermodynamic model;
4/ We modified our notations for the figures of merit to better distinguish those pertaining to the noninteracting electron gas and those pertaining to the 2D fluctuating Cooper pairs;
5/ We give more detail on the 2D fluctuating Cooper pairs, especially in the new Section 2.2.3;
6/ The new Section 3 is now about our results, numerical and experimental - and it contains parts of the former section 4;
7/ Parts of the former Section 3, which was dedicated to the experimental, notably former sections 3.1 and 3.2, have been moved to the appendix D;
8/ The new Section 4 is dedicated to our discussion, which now includes nematic fluctuations;
9/ The Section Conclusion has been expanded to provide a sharper recap of the work done, and include additional remarks to stress the importance of the fluctuating regimes and briefly indicate the potential for follow-up works as themoelectricity in fluctuating regimes near a phase transition is clearly a path to explore with dedicated experiments and the development of realistic models;
10/ Appendix A has been completed with detail on the parameters used for our numerical simulations.
11/ The bibliography section contains 17 new references.