Conductance and Stochastic Switching of Ligand‐Supported Linear Chains of Metal Atoms

Chen, I‐Wen Peter; Fu, Ming‐Dung; Tseng, W. F.; Yu, Jianyuan; Wu, Sung-Hsun; Ku, Chia-Jui; Chen, Chun‐Hsien; Peng, Shie‐Ming

doi:10.1002/anie.200600800

Cited by 182 publications

(104 citation statements)

References 39 publications

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“…Thes ignature of ELA was unambiguously characterized by EC-gated i-V curves,a nd the conductance behavior will be analyzed by simulations involving co-tunneling and sequential tunneling mechanisms.Thes ingle-molecule conductance of pentametallic EMACs was determined by EC-STM BJ at fixed E wk (Table 1; for experimental details,s ee the Supporting Information). TheE Cr esults are consistent with our previous study [19] where the oxidized EMACs were prepared by chemical oxidation of the neutral forms.H ence,t he afore-…”

supporting

confidence: 90%

Energy‐Level Alignment for Single‐Molecule Conductance of Extended Metal‐Atom Chains

et al. 2015

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The use of single-molecule junctions for various functions constitutes ac entral goal of molecular electronics. The functional features and the efficiency of electron transport are dictated by the degree of energy-level alignment (ELA), that is,the offset potential between the electrode Fermi level and the frontier molecular orbitals.Examples manifesting ELA are rare owingt oe xperimental challenges and the large energy barriers of typical model compounds.I nt his work, singlemolecule junctions of organometallic compounds with five metal centers joined in acollinear fashion were analyzed. The single-molecule i-V scans could be conducted in ar eliable manner,and the E FMO levels were electrochemically accessible. When the electrode Fermi level (E F )i sc lose to the frontier orbitals (E FMO )o ft he bridging molecule,l arger conductance was observed. The smaller j E F ÀE FMO j gap was also derived quantitatively,u nambiguously confirming the ELA. The mechanism is described in terms of atwo-level model involving co-tunneling and sequential tunneling processes.Electron transport is an essential theme across major disciplines and is of utmost importance to the success of molecule-based electronic devices.F or further improving such systems,a nu nderstanding of the interfacial transport processes,which can be analyzed in terms of the energy-level alignment (ELA), is crucial.[1] As mall barrier height (f B ), that is,the difference between the electrode Fermi level (E F ) and the frontier molecular orbitals (E FMO ), is expected to lead to facile transport. Thedegree of ELA for thin-film devices is typically unveiled by ultraviolet photoelectron spectroscopy (UPS).[1] However,f or ultimate miniaturization down to the single-molecule level, the relatively large beam size of UPS renders it unsuitable for probing local structures.M oreover, each single-molecule junction confers only one f B .The lack of systematic changes in f B makes the correlation with electrontransport efficiencydifficult. To this end, E FMO can be shifted with ag ate electrode by the field effect with single-molecule transistors (SMTs).[2] Unfortunately,S MT studies are very limited owing to fabrication difficulties.S canning tunneling microscopy (STM) based break junctions have been shown to be ac onvenient method for creating single-molecule junctions, [3] and the tuning of E F and f B is achievable through electrochemical control (hereafter referred to as EC-STM BJ) by driving the potential of the working electrode (E wk ) against that of the reference electrode. [4][5][6][7][8] Thus far, the effect of f B on the single-molecule conductance has only been proposed sporadically.[6-9] Most EC-STM BJ studies were performed at fixed E wk values and unable to monitor the system upon E F approaching E FMO .EC studies of single-molecule conductance focus mostly on organic redox moieties. [5,[7][8][9][10] Examples of organometallic compounds are rare and limited to those with one [11][12][13] or two [14,15] metal centers,s uch as ferrocenedicarbo...

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confidence: 90%

Energy‐Level Alignment for Single‐Molecule Conductance of Extended Metal‐Atom Chains

et al. 2015

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“…The blinking frequency was found to increase at high temperatures, suggesting thermally activated bond breaking processes at the metal-molecule contacts [127]. In break junction experiments, the two-level stochastic switching has also been observed in various metal/molecule/metal junctions, which were attributed to thermal fluctuations of the electrode-molecule bonding sites and concomitant change in the electrode-molecule coupling strength [128–130]. These findings indicate that binary switches can be made by exploiting the geometrical dependence of the single-molecule conductance through developing a way to control the molecular conformations and metal-molecule contact configurations [131].…”

Section: Single-molecule Electronics Devicesmentioning

confidence: 99%

Single Molecule Electronics and Devices

Tsutsui

Taniguchi

2012

Sensors

128

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The manufacture of integrated circuits with single-molecule building blocks is a goal of molecular electronics. While research in the past has been limited to bulk experiments on self-assembled monolayers, advances in technology have now enabled us to fabricate single-molecule junctions. This has led to significant progress in understanding electron transport in molecular systems at the single-molecule level and the concomitant emergence of new device concepts. Here, we review recent developments in this field. We summarize the methods currently used to form metal-molecule-metal structures and some single-molecule techniques essential for characterizing molecular junctions such as inelastic electron tunnelling spectroscopy. We then highlight several important achievements, including demonstration of single-molecule diodes, transistors, and switches that make use of electrical, photo, and mechanical stimulation to control the electron transport. We also discuss intriguing issues to be addressed further in the future such as heat and thermoelectric transport in an individual molecule.

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“…[8][9][10][11][12] The molecular conductance of various types of redox-active polynuclear metal complexes has also been measured by embedding molecules betweent wo or three terminals. During these measurements, single molecular conductivity, [13] and other characteristicp henomena such as rectification, [14] the Coulombb lockade effect, and the Kondoe ffect [15] were encountered. Recently,m olecular rectification based on redox-active complexes has been reported, in which an asymmetric potential energy between junctions, for example, electrode j molecule or electrode A j molecule j electrode Bc aused the rectification.…”

Section: Introductionmentioning

confidence: 99%

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes

Nagashima

Ozawa

Suzuki

et al. 2015

Chemistry A European J

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Photoresponsive molecular memory films were fabricated by a layer-by-layer (LbL) assembling of two dinuclear Ru complexes with tetrapodal phosphonate anchors, containing either 2,3,5,6-tetra(2-pyridyl)pyrazine or 1,2,4,5-tetra(2-pyridyl)benzene as a bridging ligand (Ru-NP and Ru-CP, respectively), using zirconium phosphonate to link the layers. Various types of multilayer homo- and heterostructures were constructed. In the multilayer heterofilms such as ITO||(Ru-NP)m |(Ru-CP)n , the difference in redox potentials between Ru-NP and Ru-CP layers was approximately 0.7 V, which induced a potential gradient determined by the sequence of the layers. In the ITO||(Ru-NP)m |(Ru-CP)n multilayer heterofilms, the direct electron transfer (ET) from the outer Ru-CP layers to the ITO were observed to be blocked for m>2, and charge trapping in the outer Ru-CP layers became evident from the appearance of an intervalence charge transfer (IVCT) band at 1140 nm from the formation of the mixed-valent state of Ru-CP units, resulting from the reductive ET mediation of the inner Ru-NP layers. Therefore, the charging/discharging ("1"and "0") states in the outer Ru-CP layers could be addressed and interconverted by applying potential pulses between -0.5 and +0.7 V. The two states could be read out by the direction of the photocurrent (anodic or cathodic). The molecular heterolayer films thus represent a typical example of a photoresponsive memory device; that is, the writing process may be achieved by the applied potential (-0.5 or +0.7 V), while the readout process is achieved by measuring the direction of the photocurrent (anodic or cathodic). Sequence-sensitive multilayer heterofilms, using redox-active complexes as building blocks, thus demonstrate great potential for the design of molecular functional devices.

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Conductance and Stochastic Switching of Ligand‐Supported Linear Chains of Metal Atoms

Cited by 182 publications

References 39 publications

Energy‐Level Alignment for Single‐Molecule Conductance of Extended Metal‐Atom Chains

Energy‐Level Alignment for Single‐Molecule Conductance of Extended Metal‐Atom Chains

Single Molecule Electronics and Devices

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes

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