A 17 GHz molecular rectifier

Trasobares, Jorge; Vuillaume, D.; Théron, Didier; Nicolas, Clément

doi:10.1038/ncomms12850

Cited by 99 publications

(132 citation statements)

References 90 publications

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“…Our most interesting results are close to resonance Ω 0 = 2g. The maximum frequency of ac drive currently experimentally realizable is ∼ 10GHz [79]. This means to observe the above effects g ∼ 0.01meV .…”

Section: Asymmetric Ac Drivementioning

confidence: 94%

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Purkayastha

2017

Phys. Rev. B

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Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments and more. Here, we formulate a rigorous microscopic theory of an out-of-equilibrium open quantum system of non-interacting particles on a lattice weakly coupled bilinearly to multiple baths and driven by periodically varying thermodynamic parameters like temperature and chemical potential of the bath. The particles can be either bosonic or fermionic and the lattice can be of any dimension and geometry. Based on Redfield quantum master equation under Born-Markov approximation, we derive a linear differential equation for equal time two-point correlation matrix, sometimes also called single-particle density matrix, from which various physical observables, for example, current, can be calculated. Various interesting physical effects, such as resonance, can be directly read-off from the equations. Thus, our theory is quite general gives quite transparent and easy-to-calculate results. We validate our theory by comparing with exact numerical simulations. We apply our method to a generic open quantum system, namely a double-quantum dot coupled to leads with modulating chemical potentials. Two most important experimentally relevant insights from this are : (i) time-dependent measurements of current for symmetric oscillating voltages (with zero instantaneous voltage bias) can point to the degree of asymmetry in the system-bath coupling, and (ii) under certain conditions, time-dependent currents can exceed time-averaged currents by several orders of magnitude, and can therefore be detected even when the average current is below the measurement threshold. A. IntroductionThe dynamics of a quantum system coupled to an external environment (so-called "open" quantum system) are a result of the intricate interplay between the coherent evolution of the quantum degrees of freedom, the structure of the environment and the form and strength of the system-environment coupling. From quantum cavities [1-3] and superconducting qubits [4][5][6][7][8][9] , through quantum dots [10][11][12][13][14][15], molecular junctions [16][17][18][19][20][21][22][23][24][25][26][27] and cold atoms [28][29][30][31] , to excitons traveling in photosynthetic complexes [32][33][34][35], open quantum systems show dynamics which can be far richer and more surprising than their coherent (environment-free) counterparts.Recent ideas of designing a quantum state by engineering a specific environment [36][37][38][39][40][41][42] or by a periodic modulation of the open system's Hamiltonian [16,43,44] open a path to new forms of control over quantum systems. Combining these two concepts of time-periodic modulations and environment (bath) engineering, here we study the dynamics of open quantum systems where the environment thermodynamic parameters are periodically modulated. Even though there exists formally exact methods of treating such set-ups...

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Section: Asymmetric Ac Drivementioning

confidence: 94%

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Purkayastha

2017

Phys. Rev. B

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“…Consequently, one need to design a molecular junction considering an optimum number of molecules in parallel in order to increase G of the junction as much as possible, while keeping C small enough. The NMJ approach is a good compromise with reported G of about 0.36 mS for Au/ferrocenylalkylthiol (FcC 11 SH)/PtIr junction . The second issue is that high frequency (GHz and above) measurements usually require devices matching a 50 Ω impedance, far below the “high‐impedance” of molecular devices.…”

Section: Nanodot Molecular Junctionsmentioning

confidence: 99%

Molecular Electronics: From Single‐Molecule to Large‐Area Devices

Vuillaume

2019

ChemPlusChem

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This Minireview focuses on conductance measurements on molecular junctions containing few tens of molecules, which are carried out by using two approaches: 1) conducting atomic force microscopy to study self‐assembled monolayers on metal surfaces, and 2) tiny molecular junctions made of metal nanodots (diameter <10 nm), covered by fewer than 100 molecules and studied by conducting atomic force microscopy. In particular, this latter approach has new results to be obtained, or to previous results to be revisited which are reviewed here: 1) how the electron‐transport properties of molecular junctions are modified by mechanical constraint, 2) the role of intermolecular interactions on the shape of conductance histograms of molecular junctions, and 3) the demonstration that a molecular diode can operate in the microwave regime up to 18 GHz.

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“…However, for many of these combinations, the peak current is low. Interestingly, the high current combinations (red dots) form a cloud which extends from 0.5 V to 1.0 V for ratios varying between 10 4 till 10 6 . This cloud is attributed to combinations of side groups of which the sites are well aligned.…”

Section: View Article Onlinementioning

confidence: 99%

“…We then investigate how the molecule can be engineered by the means of chemical substitution to align the sites at a particular bias voltage. We eventually show that the molecule designed with four sites represents a drastic improvement compared to a two-site molecule, with RR approaching 10 6 , competitive with siliconbased diodes.…”

mentioning

confidence: 99%

Design of an efficient coherent multi-site single-molecule rectifier

Perrin

Doelman

Eelkema

et al. 2017

Phys. Chem. Chem. Phys.

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aWe propose the design of a single-molecule diode with a rectification ratio exceeding a million. The employed mechanism is based on coherent resonant charge transport across a molecule that consists of four conjugated sites coupled by non-conjugated bridges. Using density functional theory calculations, we rationalize the design of the molecule and demonstrate the crucial role of aligning the sites at a specific voltage. Rectification ratios are calculated for a series of chemical substituents and demonstrate that with careful molecular design, high rectification ratios can be achieved. Finally, we comment on the shortcomings of our approach, how further improvements can be obtained and discuss some of the experimental challenges.Molecular diodes have been attracting much attention recently, both in self-assembled monolayers 1-7 and on the single-molecule scale. [8][9][10][11][12][13][14][15][16] Even though the rectifier has been the seminal device which launched the field of single-molecule electronics, 17 up to date, their performance have many shortcomings. In particular, their rectification ratios (RR) are orders of magnitude lower than typical semiconducting rectifiers. The highest RR reported experimentally on a single-molecule junction 15 is about 600, and is no match for a semiconducting diode where ratios exceeding 10 6 are common. In that study, a molecular backbone was considered which consisted of two identical, weakly-coupled conjugated parts. In such a system, current flows coherently when both halves are on resonance, i.e., the sites are aligned with each other within the bias window. The alignment of the two sites can be modified by applying a bias voltage and/or by chemical substituents. With proper design, one can align the sites at zero bias, while misaligning them at finite bias, yielding negative differential conductance. 18 One can also align the sites at a finite bias, 15,19-22 and achieve single-molecule rectification.Based on a similar principle, here we investigate theoretically how the rectification ratio of single-molecule diodes can be significantly enhanced by the addition of more sites in series, as shown in as presented in Fig. 1b. Low RR are primarily caused by a high reverse current. Adding more sites in series leads to a strong suppression of the reverse current, thereby drastically improving the RR. However, the addition of sites comes at the cost of an increased molecular complexity and number of model parameters. In this study, we first focus on the design of a molecule which behaves as having four sites in series. For this purpose, we use density functional theory (DFT) calculations. We then investigate how the molecule can be engineered by the means of chemical substitution to align the sites at a particular bias voltage. We eventually show that the molecule designed with four sites represents a drastic improvement compared to a two-site molecule, with RR approaching 10 6 , competitive with siliconbased diodes.1 Design guidelines Fig. 1 depicts the concept of a rectifier...

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A 17 GHz molecular rectifier

Cited by 99 publications

References 90 publications

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Molecular Electronics: From Single‐Molecule to Large‐Area Devices

Design of an efficient coherent multi-site single-molecule rectifier

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