Impact of contact couplings on thermoelectric properties of anti, Fano, and Breit-Wigner resonant junctions

Quantum interference is a well-known phenomenon which results in unique features of the transmission spectra of molecular junctions at the nanoscale. We investigate and compare the thermoelectric properties of three types of junctions like the anti, Breit-Wigner, and Fano resonances. Due to its asym...

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Bibliographic Details
Published in:Journal of applied physics 2016-11, Vol.120 (18)
Main Authors: Wang, Rui-Ning, Dong, Guo-Yi, Wang, Shu-Fang, Fu, Guang-Sheng, Wang, Jiang-Long
Format: Article
Language:English
Subjects:
Applied physics
Coupling (molecular)
Couplings
Crossovers
Electric contacts
Electrical junctions
Figure of merit
Interference
Properties (attributes)
Seebeck effect
Thermoelectricity
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Summary:Quantum interference is a well-known phenomenon which results in unique features of the transmission spectra of molecular junctions at the nanoscale. We investigate and compare the thermoelectric properties of three types of junctions like the anti, Breit-Wigner, and Fano resonances. Due to its asymmetric line-shaped transmission function, Fano resonances lead to a larger thermoelectric figure of merit (ZT) than the symmetric anti and Breit-Wigner resonances. The occurrence of quantum interference in molecular and other nanoscale junctions is independent of contact couplings between the sandwiched molecules and left/right electrodes. However, it is found that the contact couplings determine the electric and thermoelectric performances of quantum interference junctions. In anti-resonant junctions, the Seebeck coefficient is enhanced by strong contact couplings. By contrast, for Breit-Wigner resonant junctions, this same property will increase in the weak contact coupling regime. Contrary to what is observed for anti and Breit-Wigner resonant junctions, some optimal contact couplings are found in Fano-resonant junctions for which the maximum Seebeck coefficient and ZT are obtained. Finally, thermoelectric properties are also investigated when the resonances crossover from Breit-Wigner to Fano types and, subsequently, to anti resonances.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4967751