Current-induced mechanical torque in chiral molecular rotors

• Richard Korytár and
• Ferdinand Evers

Beilstein J. Nanotechnol. 2023, 14, 711–721, doi:10.3762/bjnano.14.57

• charge carrier and the mass of the helix per winding number. Keywords: molecular junctions; molecular motors; molecular switches; Introduction Experiments employing scanning tunneling microscopy (STM) have achieved the directed rotation of molecules controlled by an electrical current. Correspondingly

• particle does not vanish. In this situation, the rotation trivially appears due to the angular momentum transfer (“garden hose effect”). This situation represents molecular junctions where the incoming or outgoing current can carry a non-vanishing angular momentum. We present the characteristics of the

• linear response (under the threshold current). A small symmetry breaking is needed in order to discriminate between the three states. Quantum effects are responsible for a rich transport phenomenology of molecular junctions [20]. Here, we pause to discuss quantum effects related to the electronic degrees

Impact of device design on the electronic and optoelectronic properties of integrated Ru-terpyridine complexes

• Max Mennicken,
• Sophia Katharina Peter,
• Corinna Kaulen,
• Ulrich Simon and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2022, 13, 219–229, doi:10.3762/bjnano.13.16

• -ligand charge transfer absorption bands and a relatively long lifetime of the triplet state as well as voltage-driven molecular switching in solid-state molecular junctions [11][12][13][14][15]. In addition, Ru(TP)2-complexes and the corresponding supramolecular wires exhibit a rod-like structure, which

Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower

• Rouzhaji Tuerhong,
• Mauro Boero and
• Jean-Pierre Bucher

Beilstein J. Nanotechnol. 2019, 10, 1243–1250, doi:10.3762/bjnano.10.124

• quantum-dot devices, those on molecular junctions and in the presence of Kondo correlations are more recent [34][35]. Here, we analyzed the influence of a temperature gradient on the conductance spectrum of the MnPc molecule in the STM junction, as shown schematically in Figure 3a. Prior to the experiment

Electronic conduction during the formation stages of a single-molecule junction

• Atindra Nath Pal,
• Tal Klein,
• Ayelet Vilan and
• Oren Tal

Beilstein J. Nanotechnol. 2018, 9, 1471–1477, doi:10.3762/bjnano.9.138

• junction; molecular vibration; quantum interference; shot noise; Introduction Single-molecule junctions serve as a versatile atomic-scale laboratory for quantum electronic transport [1][2]. The formation of such molecular junctions, where a molecule is suspended as a bridge between two metallic electrodes

• studies [1][2]. However, information about the conductance properties of such molecular junctions at their early stages of formation is missing. In fact, the conductance signature of premature configurations of molecular junctions (before breaking the atomic scale contact) was studied only for diatomic

• cryogenic vacuum conditions. Molecular junctions are prepared by sublimating vanadocene molecules (95%, Buchem, further purified in situ), from a locally heated molecular source towards the metallic junction, while repeatedly breaking and reforming the junction between the two electrodes to study molecular

Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions

• Youngsang Kim,
• Safa G. Bahoosh,
• Dmytro Sysoiev,
• Thomas Huhn,
• Fabian Pauly and
• Elke Scheer

Beilstein J. Nanotechnol. 2017, 8, 2606–2614, doi:10.3762/bjnano.8.261

• between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and

• : inelastic electron tunneling spectroscopy; molecular junction; photochromic; single molecule; Introduction Molecular junctions hold promise for the realization of novel miniaturized electronic circuits [1][2][3][4][5][6] as well as for thermoelectric energy conversion devices [7][8][9][10]. Optoelectronic

• , including the energy of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and their coupling to electrodes. This behavior results in a change of the charge transport properties of the corresponding molecular junctions, most prominently of the electrical

Adsorbate-driven cooling of carbene-based molecular junctions

• Giuseppe Foti and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 2060–2068, doi:10.3762/bjnano.8.206

• adsorbate is fundamentally different from that of anchoring groups in molecular junctions (R–NH2): here NH2 acts as an acceptor, while as anchoring group, amines are electron donors [42]. In Supporting Information File 1, we show a comparison of the plane-averaged electron density difference upon adsorption

• each other. In summary, we have shown that a species adsorbed in the vicinity of a molecular junction can influence the heating and cooling dynamics of the conducting molecule. This affects not only the elastic transport properties but also the stability of molecular junctions under an applied bias. We

Role of solvents in the electronic transport properties of single-molecule junctions

• Katharina Luka-Guth,
• Sebastian Hambsch,
• Andreas Bloch,
• Philipp Ehrenreich,
• Bernd Michael Briechle,
• Filip Kilibarda,
• Torsten Sendler,
• Dmytro Sysoiev,
• Thomas Huhn,
• Artur Erbe and
• Elke Scheer

Beilstein J. Nanotechnol. 2016, 7, 1055–1067, doi:10.3762/bjnano.7.99

• molecules in a solvent enables their diffusion to the metal electrodes and thus the repeated formation of new and independent junctions when separating the electrodes, signalled by the formation of steps in the conductance-vs-distance curves. The conductance GJ of these molecular junctions is then ascribed

• solvent for single-molecule transport studies for molecular junctions in the conductance range above 10−4G0 only. The percentage of open-loop I–Vs of Tol is comparable with the one of TCB. Most curves cannot be fitted, neither with the SLM nor with the SM, although S-shaped I–Vs may appear in a wide

• the hysteresis discussed above. For Tol and TCB occasionally very long breaking traces are observed that indicate the formation of molecular junctions or even stacking of solvent molecules [16]. The observation of fast decrease of conductance corresponds to a high tunnel barrier Φ or a high |E0

Thermo-voltage measurements of atomic contacts at low temperature

• Ayelet Ofarim,
• Bastian Kopp,
• Thomas Möller,
• León Martin,
• Johannes Boneberg,
• Paul Leiderer and
• Elke Scheer

Beilstein J. Nanotechnol. 2016, 7, 767–775, doi:10.3762/bjnano.7.68

• temperature gradients into electrical energy and for the local energy dissipation. More fundamentally, the study of thermoelectric effects in atomic-scale nanostructures and in molecular junctions gives important additional information of charge transport [2][3][4]. The thermopower is quantified by the

Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations

• Alberto Nocera,
• Carmine Antonio Perroni,
• Vincenzo Marigliano Ramaglia and
• Vittorio Cataudella

Beilstein J. Nanotechnol. 2016, 7, 439–464, doi:10.3762/bjnano.7.39

• Sant’Angelo, Via Cintia, I-80126 Napoli, Italy 10.3762/bjnano.7.39 Abstract Background: Soft nanosystems are electronic nanodevices, such as suspended carbon nanotubes or molecular junctions, whose transport properties are modulated by soft internal degrees of freedom, for example slow vibrational modes

• consequence, intriguing nonlinear phenomena, such as hysteresis, switching, and negative differential conductance have been observed in molecular junctions. In conducting molecules, either the center of mass oscillations [9], or thermally induced acoustic phonons [10] can be the source of coupling between

• electronic and vibrational degrees of freedom. Nanoelectromechanical systems (NEMS) are devices similar to molecular junctions. Typically, they consist of a nanobeam resonator that is coupled to an electronic quantum dot junction. Famous examples of NEMS are suspended carbon nanotube (CNT) resonators, which

Invariance of molecular charge transport upon changes of extended molecule size and several related issues

• Ioan Bâldea

Beilstein J. Nanotechnol. 2016, 7, 418–431, doi:10.3762/bjnano.7.37

• properties of the solid itself, which are practically unaffected by the electrodes [16]. Things drastically change in molecular junctions. There, upon contacting to infinite electrodes, the properties of the embedded molecule can be substantially modified with respect to the isolated molecule. This is

• potential landscape are. Needless to say, these are all highly nontrivial tasks for realistic/DFT approaches, for which even the correct description of the both (positive and negative) bias polarities in simpler molecular junctions is an issue (see, e.g., the discussion related to Figure 5 in [22]). WBL

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• significantly affect the charge transport properties of the molecular junctions [55]. Nevertheless, these anchoring groups have been explored most frequently when attached to core structures that are not highly conjugated and exhibit poor conductivity (e.g., saturated alkanes) [26][30][56]. In contrast, highly

• with oxygen and can be handled even under ambient conditions in the laboratory before its surface functionalization with organosulfur compounds. The covalent bond between sulfur and gold gives rise to robust and reasonably conductive single-molecular junctions of adsorbed molecules on gold substrates

• also describe the emerging methods being used for the characterization of molecular junctions on the metal surfaces, and discuss the potential for the future research and applications. Finally, the authors apologize to their colleagues in the community for the strange wording describing their

Effects of electronic coupling and electrostatic potential on charge transport in carbon-based molecular electronic junctions

• Richard L. McCreery

Beilstein J. Nanotechnol. 2016, 7, 32–46, doi:10.3762/bjnano.7.4

• Richard L. McCreery Department of Chemistry, University of Alberta, Edmonton, AB, Canada and National Institute for Nanotechnology, National Research Council, Canada 10.3762/bjnano.7.4 Abstract Molecular junctions consisting of 2–20 nm thick layers of organic oligomers oriented between a

• more common metal/molecule or silicon/molecule structures in many reported molecular junctions. Theoretical observations based on density functional theory are presented here, which model carbon-based molecular junctions as single molecules and oligomers between fragments of graphene. Electronic

• approximately tracked the observed conductance. We use here a conceptually similar approach for carbon-based molecular junctions by considering the electronic coupling between the G9 “contacts” of the G9–molecule–G9 system depicted in Figure 1. We consider the unmodified G9 clusters of Table 2 as models of a

Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

• Riccardo Frisenda,
• Mickael L. Perrin and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 2477–2484, doi:10.3762/bjnano.6.257

• breaking trace in Figure 2a, a plateau in the conductance is observed, in this particular case around 5·10−4G0 a value that matches well previous studies on OPE3 dithiol molecular junctions [23]. By increasing the distance between the electrodes, one can eventually break the molecular junction

High electronic couplings of single mesitylene molecular junctions

• Yuki Komoto,
• Shintaro Fujii,
• Tomoaki Nishino and
• Manabu Kiguchi

Beilstein J. Nanotechnol. 2015, 6, 2431–2437, doi:10.3762/bjnano.6.251

• transport properties of single mesitylene (1,3,5-trimethylbenzene) molecular junctions. The electronic conductance and the current–voltage characteristics of mesitylene molecules wired into Au electrodes were measured by a scanning tunnelling microscopy-based break-junction method at room temperature in a

• liquid environment. We found the molecular junctions exhibited two distinct conductance states with high conductance values of ca. 10−1G0 and of more than 10−3G0 (G0 = 2e2/h) in the electronic conductance measurements. We further performed a statistical analysis of the current–voltage characteristics of

• the molecular junctions in the two states. Within a single channel resonant tunnelling model, we obtained electronic couplings in the molecular junctions by fitting the current–voltage characteristics to the single channel model. The origin of the high conductance was attributed to experimentally

Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

• David Rakhmilevitch and
• Oren Tal

Beilstein J. Nanotechnol. 2015, 6, 2417–2422, doi:10.3762/bjnano.6.249

• demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport. Keywords: correlated systems

• ; electron–phonon interactions; Kondo effect; molecular junctions; vibrations; Introduction Molecular junctions are an attractive test-bed for electronic effects such as Kondo physics [1][2][3][4][5] and electron–vibration interaction [6][7][8][9][10]. These junctions are composed of individual molecules

• suspended between two metallic electrodes. Interestingly, Kondo transport can take place in molecular junctions when an unpaired spin, localized on the molecule, is antiferromagnetically screened by the conduction electrons of the metallic electrodes. This correlated many-body state leads to an enhanced

Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

• Tino Wagner,
• Hannes Beyer,
• Patrick Reissner,
• Philipp Mensch,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2015, 6, 2193–2206, doi:10.3762/bjnano.6.225

• modulation; Kalman filter; Kelvin probe force microscopy; sidebands; Introduction Device performance of current nanoelectronic devices, and even more so of potential future generations including nanowires or molecular junctions, critically depends on transport properties varying on a length scale of a few

Thermoelectricity in molecular junctions with harmonic and anharmonic modes

• Bijay Kumar Agarwalla,
• Jian-Hua Jiang and
• Dvira Segal

Beilstein J. Nanotechnol. 2015, 6, 2129–2139, doi:10.3762/bjnano.6.218

• electrical and thermal conductances are sensitive to whether the mode is harmonic/anharmonic, the Seebeck coefficient, the thermoelectric figure-of-merit, and the thermoelectric efficiency beyond linear response, conceal this information. Keywords: counting statistics; efficiency; molecular junctions

• , the model allows for simulations of transport characteristics in conjugated molecular junctions with delocalized electrons. In this work, we focus on a different class of molecular junctions as depicted in Figure 1. In such systems, two electronic levels are coupled via a weak tunneling element, but

• thermopower, a linear response quantity, also referred to as the Seebeck coefficient, is utilized as an independent tool for probing the energetics of molecular junctions [17][18][19][20][21][22][23][24]. Experimental efforts identified orbital hybridization, contact-molecule energy coupling and geometry, and

Large-voltage behavior of charge transport characteristics in nanosystems with weak electron–vibration coupling

• Tomáš Novotný and
• Wolfgang Belzig

Beilstein J. Nanotechnol. 2015, 6, 1853–1859, doi:10.3762/bjnano.6.188

• ) the atomic/molecular junctions loose their structural stability and eventually break down. In this respect, the achievable “large-voltage” range may be fairly limited and, thus, our conclusions irrelevant. However, we believe that this is not the case. As we explicitly showed in [19] the large-voltage

Conductance through single biphenyl molecules: symmetric and asymmetric coupling to electrodes

• Karthiga Kanthasamy and
• Herbert Pfnür

Beilstein J. Nanotechnol. 2015, 6, 1690–1697, doi:10.3762/bjnano.6.171

• contacts and the chemical bonds formed between metallic electrodes and molecules determine to a large extent the conductive properties of single molecular junctions, which represent the smallest possible active elements in an electronic circuit. We therefore investigated in a comparative study, using the

Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

• Riccardo Frisenda,
• Simge Tarkuç,
• Elena Galán,
• Mickael L. Perrin,
• Rienk Eelkema,
• Ferdinand C. Grozema and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 1558–1567, doi:10.3762/bjnano.6.159

• to the stress-releasing jump-out-of contact of the gold adatoms accompanied by the instantaneous formation of a few Å gap between the now separated gold electrodes. In the region below 1G0 the successful formation of molecular junctions is evidenced by the appearance of conductance plateaus that

• conductance, and traces where no molecule was trapped between the electrode, showing an exponential decay of the conductance. The molecular junctions show up as broad, flat high-count regions that extend for around 1 nm; these indicate the most probable value for the single-molecule junction conductance. From

• total displacement suggests that we can stretch the single molecules between the MCBJ gold nano-contacts. To better understand the origin of the difference in conductance between the four different anchored molecules we have measured I–Vs characteristics of the individual molecular junctions as a

Alternative types of molecule-decorated atomic chains in Au–CO–Au single-molecule junctions

• Zoltán Balogh,
• Péter Makk and
• András Halbritter

Beilstein J. Nanotechnol. 2015, 6, 1369–1376, doi:10.3762/bjnano.6.141

• way. As the microscopic details of such molecular junctions can vary from experiment to experiment, a statistical analysis is necessary. The break junction method allows for the statistical investigation of molecular junctions: by closing the junction the metallic electrodes can be reconnected, and

• afterwards by stretching and breaking the junction, new molecular junctions can be formed. During the rupture conductance traces are recorded, i.e., the conductance of the breaking wire is measured as a function of electrode displacement. By repeating the break-junction measurement several thousand times a

• by the appearance of new peaks in the histograms [1][2]. However, to determine the details of the formation of molecular junctions further analysis is required [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Important information can be

Can molecular projected density of states (PDOS) be systematically used in electronic conductance analysis?

• Tonatiuh Rangel,
• Gian-Marco Rignanese and
• Valerio Olevano

Beilstein J. Nanotechnol. 2015, 6, 1247–1259, doi:10.3762/bjnano.6.128

• Berkeley National Laboratory, Berkeley, California 94720, USA CNRS, Institut Néel, F-38042 Grenoble, France University Grenoble Alpes, F-38000 Grenoble, France 10.3762/bjnano.6.128 Abstract Using benzenediamine and benzenedithiol molecular junctions as benchmarks, we investigate the widespread analysis of

• molecular junctions in laboratories, such as electromigration methods, mechanical strain and scanning tunneling microscopy to open small gaps between gold leads that can host (with a small but non-negligible probability) single molecules from a wetting solution [1][2][3]. The complete characterization of

• ]. From this breakthrough work, it is now possible to quote the zero-bias conductance of some molecular junctions such as benzene-diamine (BDA) and benzene-dithiol (BDT) between gold leads. Nevertheless, important characterization uncertainties still persist. For instance, in these experiments, the

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• molecular junctions [37][38], exciton migration control [39], top-contact metallization [24][40][41], optical and opto-electronic applications [42][43], modulation of the electrical properties of the junction [24], inclusion of a metal atom in the organic structure of a molecular wire [44], and electrical

• , forming stable and reproducible molecular junctions with relatively high conductance, and statistically high junction formation probabilities in the break junction method. In addition, the chemical inertness of the pyridyl group makes it quite attractive, since no protective groups are needed in the

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

• Chris Hellenthal,
• Kai Sotthewes,
• Martin H. Siekman,
• E. Stefan Kooij and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2015, 6, 1116–1124, doi:10.3762/bjnano.6.113

• effective barrier height. If one simply assumes that the effective barrier height is equal to the work function, the presence of image charges will lead to values for that are significantly lower than one would expect. Determining the tunnel behavior in molecular junctions can give an indication of the

• analyze direct tunneling experiments on large-area molecular junctions, Akkerman et al. included an additional exponential scaling factor in the Simmons model, which they later ascribed to the effective mass of the electrons tunneling through the molecules [26]. A similar effective mass correction has

Electroburning of few-layer graphene flakes, epitaxial graphene, and turbostratic graphene discs in air and under vacuum

• Andrea Candini,
• Nils Richter,
• Domenica Convertino,
• Camilla Coletti,
• Franck Balestro,
• Wolfgang Wernsdorfer,
• Mathias Kläui and
• Marco Affronte

Beilstein J. Nanotechnol. 2015, 6, 711–719, doi:10.3762/bjnano.6.72

• important to test it also on other types of graphene. In particular, since many envisaged applications require the use of a gate electrode to tune the molecular junctions properties, it seems appealing the use of few-layer graphene, which is still thin but much less gate-dependent than the single layer [10