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Nanostructured potential well/barrier engineering for realizing unprecedentedly large thermoelectric power factors
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Neophytou, Neophytos, Foster, Samuel, Vargiamidis, Vassilios, Pennelli, G. and Narducci, D. (2019) Nanostructured potential well/barrier engineering for realizing unprecedentedly large thermoelectric power factors. Materials Today Physics, 11 . 100159. doi:10.1016/j.mtphys.2019.100159 ISSN 2542-5293.
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WRAP-nanostructured-potential-engineering-large-thermoelectric-Neophytou-2020.pdf - Accepted Version - Requires a PDF viewer. Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0. Download (3838Kb) | Preview |
Official URL: http://dx.doi.org/10.1016/j.mtphys.2019.100159
Abstract
This work describes, through the semi-classical Boltzmann transport theory and simulation, a novel nanostructured material design that can lead to unprecedentedly high thermoelectric power factors, with improvements of more than an order of magnitude compared to optimal bulk material power factors. The design is based on a specific grain/grain-boundary (potential well/barrier) engineering such that: i) carrier energy filtering is achieved using potential barriers, combined with ii) higher than usual doping operating conditions such that high carrier velocities and mean-free-paths are utilized, iii) minimal carrier energy relaxation is achieved after passing over the barriers to propagate the high Seebeck coefficient of the barriers into the potential wells, and, importantly, iv) an intermediate dopant-free (depleted) region is formed. Thus, the design consists of a ‘three-region geometry’, in which the high doping resides in the center/core of the potential well, with a dopant-depleted region separating the doped region from the potential barriers. It is shown that the filtering barriers are optimal when they mitigate the reduction in conductivity they introduce, and this can be done primarily when they are ‘clean’ from dopants during the process of filtering. The potential wells, on the other hand, are optimal when they mitigate the reduced Seebeck coefficient they introduce by: i) not allowing carrier energy relaxation, and ii) mitigating the reduction in mobility that the high concentration of dopant impurities causes. It is shown that dopant segregation, with ‘clean’ dopant-depletion regions around the potential barriers, serves this key purpose of improved mobility toward the phonon-limited mobility levels in the wells. Using quantum transport simulations based on the non-equilibrium Green's function method as well as semi-classical Monte Carlo simulations, we also verify the important ingredients and validate this ‘clean-filtering’ design.
| Item Type: | Journal Article | ||||||||
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| Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | ||||||||
| Journal or Publication Title: | Materials Today Physics | ||||||||
| Publisher: | Elsevier | ||||||||
| ISSN: | 2542-5293 | ||||||||
| Official Date: | December 2019 | ||||||||
| Dates: |
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| Volume: | 11 | ||||||||
| Article Number: | 100159 | ||||||||
| DOI: | 10.1016/j.mtphys.2019.100159 | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Open Access (Creative Commons) | ||||||||
| Date of first compliant deposit: | 3 February 2020 | ||||||||
| Date of first compliant Open Access: | 11 November 2020 |
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