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Thermoelectric degrees of freedom determining thermoelectric efficiency

For over half a century, the development of thermoelectric materials has based on the dimensionless figure of merit [Formula: see text] , assuming that the efficiency is mainly determined by this single parameter. Here, we show that the thermoelectric conversion efficiency is determined by three ind...

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Detalles Bibliográficos
Autores principales: Ryu, Byungki, Chung, Jaywan, Park, SuDong
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8382987/
https://www.ncbi.nlm.nih.gov/pubmed/34466781
http://dx.doi.org/10.1016/j.isci.2021.102934
Descripción
Sumario:For over half a century, the development of thermoelectric materials has based on the dimensionless figure of merit [Formula: see text] , assuming that the efficiency is mainly determined by this single parameter. Here, we show that the thermoelectric conversion efficiency is determined by three independent parameters, [Formula: see text] , τ, and β, which we call the three thermoelectric degrees of freedom (DoFs). [Formula: see text] is the well-defined mean of the traditional [Formula: see text] under nonzero temperature differences. The two additional parameters τ and β are gradients of material properties and crucial to evaluating the heat current altered by nonzero Thomson heat and asymmetric Joule heat escape. Each parameter is a figure of merit. Therefore, increasing one of the three DoFs leads to higher efficiency. Our finding explains why the single-parameter theory is inaccurate. Further, it suggests an alternative direction in material discovery and device design in thermoelectrics, such as high τ and β, beyond [Formula: see text].