Length-dependent conductance and thermopower in single-molecule junctions of dithiolated oligophenylene derivatives: A density functional study

Pauly, Fabian; Viljas, J. K.; Cuevas, Juan Carlos

doi:10.1103/physrevb.78.035315

Cited by 121 publications

(169 citation statements)

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“…[161][162] Biphenyl derivatives have been considered as potential conductance switches rings can be either in the same plane or perpendicular to each other representing [163]- [165] In Figure 8 the two different states are shown depending on the conformation of the two phenyl rings. The torsion angel between the two phenyl rings of a biphenylic system is not at all fixed, it is very sensitive to its chemical environment and the substitution pattern.…”

Section: Biphenyls In Molecular Electronicsmentioning

confidence: 99%

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Shape‐Switchable Azo‐Macrocycles

et al. 2009

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The synthesis of four shape‐switchable macrocycles comprising different peripheral substituents is described. The macrocycles 1–4 consist of m‐terphenyl semicircles interlinked by two azo joints. These macrocycles were assembled from nitro‐functionalized m‐terphenyl moieties through reductive dimerization. The semicircles were assembled through Suzuki cross‐coupling reactions. The molecular weights of the macrocycles were determined by vapour pressure osmometry, because mass spectrometry failed in the cases of 2 and 3. The E → Z photoisomerization reactions were analysed by UV/Vis spectroscopy complemented by 1H NMR studies. A very slow thermal back‐reaction indicated considerable stabilization of the Z isomer. The reduced efficiency of the thermal back‐reaction probably arises from the reduced degree of freedom due to the mechanical interlinking of the two azo groups. The photostationary state consisted of all‐Z (85 %) and all‐E isomers (15 %). The E → Z transformation induced by irradiation displayed simple exponential kinetics, which indicates pairwise switching of the two azo groups in a macrocycle, at least on the timescale under investigation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Biphenyls In Molecular Electronicsmentioning

confidence: 99%

“…[165][174] [175] Figure 10 Schematic of three biphenyl conformation and the degree of -conjugation, represented by the LUMO orbitals. [112] phenyl rings most efficiently.…”

Section: Introductionmentioning

confidence: 99%

Shape‐Switchable Azo‐Macrocycles

et al. 2009

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“…Focusing on works reporting on both G and S, we note that most computational studies of linear-response transport coefficients in single molecules are limited to the coherent limit 23 , using the Landauer formula with parameters derived from first principle calculations [24][25][26][27][28][29][30][31][32][33][34] , or other coherent-transport approaches 35 . Effects of vibrations on the thermopower were assessed using scattering approaches 36,37 , or perturbatively using non-equilibrium Green's function (NEGF) [38][39][40][41][42][43] or quantum master equation (QME) methods [42][43][44][45][46] .…”

Section: Introductionmentioning

confidence: 99%

Thermopower of molecular junctions: Tunneling to hopping crossover in DNA

Korol

Kilgour

Segal

2016

The Journal of Chemical Physics

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We study the electrical conductance G and the thermopower S of single-molecule junctions, and reveal signatures of different transport mechanisms: off-resonant tunneling, on-resonant coherent (ballistic) motion, and multi-step hopping. These mechanisms are identified by studying the behavior of G and S while varying molecular length and temperature. Based on a simple one-dimensional model for molecular junctions, we derive approximate expressions for the thermopower in these different regimes. Analytical results are compared to numerical simulations, performed using a variant of Büttiker's probe technique, the so-called voltagetemperature probe, which allows us to phenomenologically introduce environmentally-induced elastic and inelastic electron scattering effects, while applying both voltage and temperature biases across the junction. We further simulate the thermopower of GC-rich DNA molecules with mediating A:T blocks, and manifest the tunneling-to-hopping crossover in both the electrical conductance and the thermopower, in accord with measurements by Y. Li et al., Nature Comm. 7, 11294 (2016).

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“…In particular, the thermoelectric response of molecular junctions, mostly focusing on the junction linear response as reflected by its Seebeck coefficient, has been recently observed (61)(62)(63)(64)(65) and theoretically analyzed (2,20,64,(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77). Most of the theoretical work has focused on junctions characterized by coherent electronic transport in which the electronic and nuclear contribution to heat transport are assumed largely independent of each other.…”

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confidence: 99%

Electron transfer across a thermal gradient

Craven

Nitzan

2016

Proc. Natl. Acad. Sci. U.S.A.

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Charge transfer is a fundamental process that underlies a multitude of phenomena in chemistry and biology. Recent advances in observing and manipulating charge and heat transport at the nanoscale, and recently developed techniques for monitoring temperature at high temporal and spatial resolution, imply the need for considering electron transfer across thermal gradients. Here, a theory is developed for the rate of electron transfer and the associated heat transport between donor-acceptor pairs located at sites of different temperatures. To this end, through application of a generalized multidimensional transition state theory, the traditional Arrhenius picture of activation energy as a single point on a free energy surface is replaced with a bithermal property that is derived from statistical weighting over all configurations where the reactant and product states are equienergetic. The flow of energy associated with the electron transfer process is also examined, leading to relations between the rate of heat exchange among the donor and acceptor sites as functions of the temperature difference and the electronic driving bias. In particular, we find that an open electron transfer channel contributes to enhanced heat transport between sites even when they are in electronic equilibrium. The presented results provide a unified theory for charge transport and the associated heat conduction between sites at different temperatures. T he study of electronic transport in molecular nanojunctions naturally involves consideration of inelastic transport, where the transporting electron can exchange energy with underlying nuclear motions (1, 2). Such studies have been motivated by the use of inelastic tunneling spectroscopy, and more recently Raman spectroscopy, as diagnostic tools on one hand, and by considerations of junction stability on the other. In parallel, there has been an increasing interest in vibrational heat transport in nanostructures and their interfaces with bulk substrates (3-11) focusing on structure-transport correlations (12-15), moleculesubstrate coupling (16-18), ballistic and diffusive transport processes (11,19), and rectification (20-22). More recently, noise (23-26), nonlinear response (e.g., negative differential heat conductance), and control by external stimuli (27, 28) have been examined. An important driving factor in this growing interest is the development of experimental capabilities that greatly improve on the ability to gauge temperatures (and "effective" temperatures in nonequilibrium systems) with high spatial and thermal resolutions (29-43) and to infer from such measurement the underlying heat transport processes. In particular, vibrational energy transport/ heat conduction in molecular layers and junctions has recently been characterized using different probes (6,19,(44)(45)(46)(47)(48)(49)(50)(51)(52).The interplay between charge and energy (electronic and nuclear) transport (53-60) is of particular interest as it pertains to the performance of energy-conversion devices, such as therm...

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Length-dependent conductance and thermopower in single-molecule junctions of dithiolated oligophenylene derivatives: A density functional study

Cited by 121 publications

References 42 publications

Shape‐Switchable Azo‐Macrocycles

Shape‐Switchable Azo‐Macrocycles

Thermopower of molecular junctions: Tunneling to hopping crossover in DNA

Electron transfer across a thermal gradient

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