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Title: Perspective: Thermal and thermoelectric transport in molecular junctions

Authors:
 [1];  [1];  [1];  [1];  [2]
  1. Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
  2. Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1349357
Grant/Contract Number:
SC0004871
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 9; Related Information: CHORUS Timestamp: 2018-02-15 01:32:12; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Cui, Longji, Miao, Ruijiao, Jiang, Chang, Meyhofer, Edgar, and Reddy, Pramod. Perspective: Thermal and thermoelectric transport in molecular junctions. United States: N. p., 2017. Web. doi:10.1063/1.4976982.
Cui, Longji, Miao, Ruijiao, Jiang, Chang, Meyhofer, Edgar, & Reddy, Pramod. Perspective: Thermal and thermoelectric transport in molecular junctions. United States. doi:10.1063/1.4976982.
Cui, Longji, Miao, Ruijiao, Jiang, Chang, Meyhofer, Edgar, and Reddy, Pramod. Tue . "Perspective: Thermal and thermoelectric transport in molecular junctions". United States. doi:10.1063/1.4976982.
@article{osti_1349357,
title = {Perspective: Thermal and thermoelectric transport in molecular junctions},
author = {Cui, Longji and Miao, Ruijiao and Jiang, Chang and Meyhofer, Edgar and Reddy, Pramod},
abstractNote = {},
doi = {10.1063/1.4976982},
journal = {Journal of Chemical Physics},
number = 9,
volume = 146,
place = {United States},
year = {Tue Mar 07 00:00:00 EST 2017},
month = {Tue Mar 07 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4976982

Citation Metrics:
Cited by: 6works
Citation information provided by
Web of Science

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  • Quantum interference (QI) phenomena between electronic states in molecular circuits offer a new opportunity to design new types of molecular devices such as molecular sensors, interferometers, and thermoelectric devices. Controlling the QI effect is a key challenge for such applications. For the development of single molecular devices employing QI effects, a systematic study of the relationship between electronic structure and the quantum interference is needed. In order to uncover the essential topological requirements for the appearance of QI effects and the relationship between the QI-affected line shape of the transmission spectra and the electronic structures, we consider a homogeneous toymore » model where all on-site energies are identical and model four types of molecular junctions due to their topological connectivities. We systematically analyze their transmission spectra, density of states, and thermoelectric properties. Even without the degree of freedom for on-site energies an asymmetric Fano peak could be realized in the homogeneous systems with the cyclic configuration. We also calculate the thermoelectric properties of the model systems with and without fluctuation of on-site energies. Even under the fluctuation of the on-site energies, the finite thermoelectrics are preserved for the Fano resonance, thus cyclic configuration is promising for thermoelectric applications. This result also suggests the possibility to detect the cyclic configuration in the homogeneous systems and the presence of the QI features from thermoelectric measurements.« less
  • Cited by 40
  • We consider optical spectroscopy of molecular junctions from the quantum transport perspective when radiation field is quantized and optical response of the system is simulated as photon flux. Using exact expressions for photon and electronic fluxes derived within the nonequilibrium Green function (NEGF) methodology and utilizing fourth order diagrammatic perturbation theory (PT) in molecular coupling to radiation field, we perform simulations employing realistic parameters. Results of the simulations are compared to the bare PT which is usually employed in studies on nonlinear optical spectroscopy to classify optical processes. We show that the bare PT violates conservation laws, while flux conservingmore » NEGF formulation mixes optical processes.« less
  • Cited by 4
  • We present a combined experimental and computational study that probes the thermoelectric and electrical transport properties of molecular junctions. Experiments were performed on junctions created by trapping aromatic molecules between gold electrodes. The end groups (-SH, -NC) of the aromatic molecules were systematically varied to study the effect of contact coupling strength and contact chemistry. When the coupling of the molecule with one of the electrodes was reduced by switching the terminal chemistry from -SH to -H, the electrical conductance of molecular junctions decreased by an order of magnitude, whereas the thermopower varied by only a few percent. This hasmore » been predicted computationally in the past and is experimentally demonstrated for the first time. Further, our experiments and computational modeling indicate the prospect of tuning thermoelectric properties at the molecular scale. In particular, the thiol-terminated aromatic molecular junctions revealed a positive thermopower that increased linearly with length. This positive thermopower is associated with charge transport primarily through the highest occupied molecular orbital, as shown by our computational results. In contrast, a negative thermopower was observed for a corresponding molecular junction terminated by an isocyanide group due to charge transport primarily through the lowest unoccupied molecular orbital.« less