Thermoelectric efficiency in nanojunctions: A comparison between atomic junctions and molecular junctions

Yu Shen Liu, Yi Ren Chen, Yu-Chang Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations

Abstract

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 (/) and temperatures (T). The theory considers the combined heat current carried by electrons and phonons. We observe a characteristic temperature: T0 = (β/γ(I))1/2. When T ≪ T0, the electronic heat current dominates the combined heat current and ZT ∞ T2. When ≫ T0, 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.

Original languageEnglish
Pages (from-to)3497-3504
Number of pages8
JournalACS Nano
Volume3
Issue number11
DOIs
StatePublished - 24 Nov 2009

Keywords

  • Atomic junction
  • Density functional theory
  • Electronic heat conductance
  • Phononic heat conductance
  • Seebeck coefficient
  • Single-molecule junction
  • Thermoelectric figure of merit
  • Thermoelectricity

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