標題: Thermoelectric Efficiency in Nanojunctions: A Comparison between Atomic Junctions and Molecular Junctions
作者: Liu, Yu-Shen
Chen, Yi-Ren
Chen, Yu-Chang
電子物理學系
Department of Electrophysics
關鍵字: thermoelectricity;Seebeck coefficient;thermoelectric figure of merit;electronic heat conductance;phononic heat conductance;atomic junction;single-molecule junction;density functional theory
公開日期: 1-Nov-2009
摘要: Using first-principles approaches, we investigate the thermoelectric efficiency, characterized by the figure of merit ZT, in metallic atomic junctions and insulating molecular junctions. To gain insight into the properties of ZT, an analytical theory is also developed to study the dependence of ZT on lengths (l) and temperatures (T). The theory considers the combined heat current carried by electrons and phonons. We observe a characteristic temperature: T(0) = (beta/gamma(l))(1/2). When T << T(0), the electronic heat current dominates the combined heat current and ZT proportional to T(2). When T >> T(0), the phononic heat current dominates the combined heat current and ZT tends to a saturation value. Moreover, the metallic atomic junctions and the insulating molecular junctions have opposite trend for the dependence of ZT on lengths, that is, ZT increases as the length increases for aluminum atomic junctions, while ZT decreases as the length increases for alkanethiol molecular junctions.
URI: http://dx.doi.org/10.1021/nn900986r
http://hdl.handle.net/11536/6496
ISSN: 1936-0851
DOI: 10.1021/nn900986r
期刊: ACS NANO
Volume: 3
Issue: 11
起始頁: 3497
結束頁: 3504
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