scholarly journals Nonlinear thermoelectric properties of molecular junctions with vibrational coupling

2010 ◽  
Vol 82 (4) ◽  
Author(s):  
M. Leijnse ◽  
M. R. Wegewijs ◽  
K. Flensberg
Keyword(s):  
Thermoelectric Properties ◽  
Molecular Junctions ◽  
Vibrational Coupling

scholarly journals High cross-plane thermoelectric performance of metallo-porphyrin molecular junctions

2017 ◽  
Vol 19 (26) ◽  
pp. 17356-17359 ◽  
Author(s):  
Mohammed Noori ◽  
Hatef Sadeghi ◽  
Qusiy Al-Galiby ◽  
Steven W. D. Bailey ◽  
Colin J. Lambert
Keyword(s):  
Metal Ions ◽  
Thermoelectric Properties ◽  
Divalent Metal ◽  
Molecular Junctions ◽  
Thermoelectric Performance ◽  
Gold Electrodes ◽  
Divalent Metal Ions

We investigated the thermoelectric properties of flat-stacked 5,15-diphenylporphyrins containing divalent metal ions Ni, Co, Cu or Zn, which are strongly coordinated with the nitrogens of pyridyl coated gold electrodes.

scholarly journals Understanding resonant charge transport through weakly coupled single-molecule junctions

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
James O. Thomas ◽  
Bart Limburg ◽  
Jakub K. Sowa ◽  
Kyle Willick ◽  
Jonathan Baugh ◽  
...  
Keyword(s):  
Charge Transport ◽  
Single Molecule ◽  
Local Environment ◽  
Single Mode ◽  
Molecular Junctions ◽  
Vibrational Coupling ◽  
Weakly Coupled ◽  
Single Molecule Electronics ◽  
Single Molecule Junctions ◽  
Quantitative Understanding

Abstract Off-resonant charge transport through molecular junctions has been extensively studied since the advent of single-molecule electronics and is now well understood within the framework of the non-interacting Landauer approach. Conversely, gaining a qualitative and quantitative understanding of the resonant transport regime has proven more elusive. Here, we study resonant charge transport through graphene-based zinc-porphyrin junctions. We experimentally demonstrate an inadequacy of non-interacting Landauer theory as well as the conventional single-mode Franck–Condon model. Instead, we model overall charge transport as a sequence of non-adiabatic electron transfers, with rates depending on both outer and inner-sphere vibrational interactions. We show that the transport properties of our molecular junctions are determined by a combination of electron–electron and electron-vibrational coupling, and are sensitive to interactions with the wider local environment. Furthermore, we assess the importance of nuclear tunnelling and examine the suitability of semi-classical Marcus theory as a description of charge transport in molecular devices.

scholarly journals Anchoring Groups Determine Conductance, Thermopower and Thermoelectric Figure of Merit of an Organic Molecular Junction

2021 ◽  
Vol 9 ◽  
Author(s):  
Saeideh Ramezani Akbarabadi ◽  
Mojtaba Madadi Asl
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Electrical Conductance ◽  
Thermal Conductance ◽  
Wide Band ◽  
Transmission Probability ◽  
Molecular Junctions ◽  
Side Group ◽  
Group Position ◽  
Anchoring Groups

Transport properties of molecular junctions are prone to chemical or conformational modifications. Perturbation of the molecule-electrode coupling with anchoring groups or functionalization of the molecule with side groups is a well-characterized method to modulate the thermoelectric properties of molecular junctions. In this study, we used wide-band approximation combined with the non-equilibrium Green’s function (NEGF) formalism to inspect conductance, thermopower and figure of merit of an anthracene molecule coupled to gold (Au) electrodes. To provide a comparative study, three different anchoring groups were used, i.e., thiol, isocyanide and cyanide. The molecule was then perturbed with the amine side group in two positions to explore the interplay between anchoring groups and the side group. We showed that the introduction of side group alters transmission probability near the Fermi energy where transmission peaks are shifted relative to the Fermi level compared to the unperturbed molecule (i.e., without side group), ultimately leading to modified electrical and thermoelectric properties. The greatest value of electrical conductance was achieved when the side-group-perturbed molecule was anchored with isocyanide, whereas the thiol-terminated molecule perturbed with the side group yielded the greatest value of thermal conductance. We found that the Wiedemann-Franz law is violated in the Au-anthracene-Au device. Furthermore, the highest thermopower and figure of merit were attained in the cyanide-terminated perturbed molecule. Our results indicate that charge donating/accepting character of the anchoring group and its interplay with the side group position can modify temperature dependency of conductance, thermopower and figure of merit which is in agreement with experimental findings in organic molecular junctions. Such modifications may potentially contribute to the understanding of emerging conductance-based memory devices designed to mimic the behavior of brain-like synapses.

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