Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance

How to achieve high thermoelectric figure of merit is still a scientific challenge. By solving the Boltzmann transport equation, thermoelectric properties can be written as integrals of a single function, the transport distribution function (TDF). In this work, the shape effects of transport distrib...

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Main Author: Jin-Cheng Zheng
Format: Article
Language:English
Published: American Association for the Advancement of Science (AAAS) 2022-01-01
Series:Research
Online Access:http://dx.doi.org/10.34133/2022/9867639
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author Jin-Cheng Zheng
author_facet Jin-Cheng Zheng
author_sort Jin-Cheng Zheng
collection DOAJ
description How to achieve high thermoelectric figure of merit is still a scientific challenge. By solving the Boltzmann transport equation, thermoelectric properties can be written as integrals of a single function, the transport distribution function (TDF). In this work, the shape effects of transport distribution function in various typical functional forms on thermoelectric properties of materials are systematically investigated. It is found that the asymmetry of TDF, characterized by skewness, can be used to describe universally the trend of thermoelectric properties. By defining symmetric and asymmetric TDF functions, a novel skewness is then constructed for thermoelectric applications. It is demonstrated, by comparison with ab initio calculations and experiments, that the proposed thermoelectric skewness not only perfectly captures the main feature of conventional skewness but also is able to predict the thermoelectric power accurately. This comparison confirms the unique feature of our proposed thermoelectric skewness, as well as its special role of connection between the statistics of TDF and thermoelectric properties of materials. It is also found that the thermoelectric performance can be enhanced by increasing the asymmetry of TDF. Finally, it is also interesting to find that the thermoelectric transport properties based on typical quantum statistics (Fermi-Dirac distributions) can be well described by typical shape parameter (skewness) for classical statistics.
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spelling doaj.art-ab96b6d44ab94516be634a0d99d5715e2024-03-02T04:52:03ZengAmerican Association for the Advancement of Science (AAAS)Research2639-52742022-01-01202210.34133/2022/9867639Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric PerformanceJin-Cheng Zheng0Department of Physics, Xiamen University, Xiamen 361005, China; Department of Physics and Department of New Energy Science and Engineering, Xiamen University Malaysia, Sepang 43900, MalaysiaHow to achieve high thermoelectric figure of merit is still a scientific challenge. By solving the Boltzmann transport equation, thermoelectric properties can be written as integrals of a single function, the transport distribution function (TDF). In this work, the shape effects of transport distribution function in various typical functional forms on thermoelectric properties of materials are systematically investigated. It is found that the asymmetry of TDF, characterized by skewness, can be used to describe universally the trend of thermoelectric properties. By defining symmetric and asymmetric TDF functions, a novel skewness is then constructed for thermoelectric applications. It is demonstrated, by comparison with ab initio calculations and experiments, that the proposed thermoelectric skewness not only perfectly captures the main feature of conventional skewness but also is able to predict the thermoelectric power accurately. This comparison confirms the unique feature of our proposed thermoelectric skewness, as well as its special role of connection between the statistics of TDF and thermoelectric properties of materials. It is also found that the thermoelectric performance can be enhanced by increasing the asymmetry of TDF. Finally, it is also interesting to find that the thermoelectric transport properties based on typical quantum statistics (Fermi-Dirac distributions) can be well described by typical shape parameter (skewness) for classical statistics.http://dx.doi.org/10.34133/2022/9867639
spellingShingle Jin-Cheng Zheng
Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
Research
title Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
title_full Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
title_fullStr Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
title_full_unstemmed Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
title_short Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance
title_sort asymmetrical transport distribution function skewness as a key to enhance thermoelectric performance
url http://dx.doi.org/10.34133/2022/9867639
work_keys_str_mv AT jinchengzheng asymmetricaltransportdistributionfunctionskewnessasakeytoenhancethermoelectricperformance