1
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Du W, Chen X, Wang T, Lin Q, Nijhuis CA. Tuning Overbias Plasmon Energy and Intensity in Molecular Plasmonic Tunneling Junctions by Atomic Polarizability. J Am Chem Soc 2024; 146:21642-21650. [PMID: 38940772 PMCID: PMC11311224 DOI: 10.1021/jacs.4c05544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 06/29/2024]
Abstract
Plasmon excitation in molecular tunnel junctions is interesting because the plasmonic properties of the device can be, in principle, controlled by varying the chemical structure of the molecules. The plasmon energy of the excited plasmons usually follows the quantum cutoff law, but frequently overbias plasmon energy has been observed, which can be explained by quantum shot noise, multielectron processes, or hot carrier models. So far, clear correlations between molecular structure and the plasmon energy have not been reported. Here, we introduce halogenated molecules (HS(CH2)12X, with X = H, F, Cl, Br, or I) with polarizable terminal atoms as the tunnel barriers and demonstrate molecular control over both the excited plasmon intensity and energy for a given applied voltage. As the polarizability of the terminal atom increases, the tunnel barrier height decreases, resulting in an increase in the tunneling current and the plasmon intensity without changing the tunneling barrier width. We also show that the plasmon energy is controlled by the electrostatic potential drop at the molecule-electrode interface, which depends on the polarizability of the terminal atom and the metal electrode material (Ag, Au, or Pt). Our results give new insights in the relation between molecular structure, electronic structure of the molecular junction, and the plasmonic properties which are important for the development of molecular scale plasmonic-electronic devices.
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Affiliation(s)
- Wei Du
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Xiaoping Chen
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
- Fujian
Provincial Key Laboratory of Modern Analytical Science and Separation
Technology, College of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou 363000, China
| | - Tao Wang
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Qianqi Lin
- Hybrid
Materials for Optoelectronics Group, Department of Molecules and Materials,
MESA+ Institute for Nanotechnology, Molecules Center and Center for
Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500AE Enschede, The Netherlands
| | - Christian A. Nijhuis
- Hybrid
Materials for Optoelectronics Group, Department of Molecules and Materials,
MESA+ Institute for Nanotechnology, Molecules Center and Center for
Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500AE Enschede, The Netherlands
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2
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Yonemoto R, Ueda R, Otomo A, Noguchi Y. Light-Emitting Electrochemical Cells Based on Nanogap Electrodes. NANO LETTERS 2023; 23:7493-7499. [PMID: 37579029 DOI: 10.1021/acs.nanolett.3c02001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
In a light-emitting electrochemical cell (LEC), electrochemical doping caused by mobile ions facilitates bipolar charge injection and recombination emissions for a high electroluminescence (EL) intensity at low driving voltages. We present the development of a nanogap LEC (i.e., nano-LEC) comprising a light-emitting polymer (F8BT) and an ionic liquid deposited on a gold nanogap electrode. The device demonstrated a high EL intensity at a wavelength of 540 nm corresponding to the emission peak of F8BT and a threshold voltage of ∼2 V at 300 K. Upon application of a constant voltage, the device demonstrated a gradual increase in current intensity followed by light emission. Notably, the delayed components of the current and EL were strongly suppressed at low temperatures (<285 K). The results clearly indicate that the device functions as an LEC and that the nano-LEC is a promising approach to realizing molecular-scale current-induced light sources.
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Affiliation(s)
- Ryo Yonemoto
- Graduate School of Science and Technology, Meiji University, Kawasaki 214-8571, Japan
| | - Rieko Ueda
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Akira Otomo
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Yutaka Noguchi
- Graduate School of Science and Technology, Meiji University, Kawasaki 214-8571, Japan
- School of Science & Technology, Meiji University, Kawasaki 214-8571, Japan
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3
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Abstract
The field of molecular electronics has grown rapidly since its experimental realization in the late 1990s, with thousands of publications on how molecules can act as circuit components and the possibility of extending microelectronic miniaturization. Our research group developed molecular junctions (MJs) using conducting carbon electrodes and covalent bonding, which provide excellent temperature tolerance and operational lifetimes. A carbon-based MJ based on quantum mechanical tunneling for electronic music represents the world's first commercial application of molecular electronics, with >3000 units currently in consumer hands. The all-carbon MJ consisting of aromatic molecules and oligomers between vapor-deposited carbon electrodes exploits covalent, C-C bonding which avoids the electromigration problem of metal contacts. The high bias and temperature stability as well as partial transparency of the all-carbon MJ permit a wide range of experiments to determine charge transport mechanisms and observe photoeffects to both characterize and stimulate operating MJs. As shown in the Conspectus figure, our group has reported a variety of electronic functions, many of which do not have analogs in conventional semiconductors. Much of the described research is oriented toward the rational design of electronic functions, in which electronic characteristics are determined by molecular structure.In addition to the fabrication of molecular electronic devices with sufficient stability and operating life for practical applications, our approach was directed at two principal questions: how do electrons move through molecules that are components of an electronic circuit, and what can we do with molecules that we cannot do with existing semiconductor technology? The central component is the molecular junction consisting of a 1-20+ nm layer of covalently bonded oligomers between two electrodes of conducting, mainly sp2-hybridized carbon. In addition to describing the unique junction structure and fabrication methods, this Account summarizes the valuable insights available from photons used both as probes of device structure and dynamics and as prods to stimulate resonant transport through molecular orbitals.Short-range (<5 nm) transport by tunneling and its properties are discussed separately from the longer-range transport (5-60 nm) which bridges the gap between tunneling and transport in widely studied organic semiconductors. Most molecular electronic studies deal with the <5 nm thickness range, where coherent tunneling is generally accepted as the dominant transport mechanism. However, the rational design of devices in this range by changing molecular structure is frustrated by electronic interactions with the conducting contacts, resulting in weak structural effects on electronic behavior. When the molecular layer thickness exceeds 5 nm, transport characteristics change completely since molecular orbitals become the conduits for transport. Incident photons can stimulate transport, with the observed photocurrent tracking the absorption spectrum of the molecular layer. Low-temperature, activationless transport of photogenerated carriers is possible for up to at least 60 nm, with characteristics completely distinct from coherent tunneling and from the hopping mechanisms proposed for organic semiconductors. The Account closes with examples of phenomena and applications enabled by molecular electronics which may augment conventional microelectronics with chemical functions such as redox charge storage, orbital transport, and energy-selective photodetection.
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Affiliation(s)
- Richard L McCreery
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
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4
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Light-Driven Charge Transport and Optical Sensing in Molecular Junctions. NANOMATERIALS 2022; 12:nano12040698. [PMID: 35215024 PMCID: PMC8878161 DOI: 10.3390/nano12040698] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 12/11/2022]
Abstract
Probing charge and energy transport in molecular junctions (MJs) has not only enabled a fundamental understanding of quantum transport at the atomic and molecular scale, but it also holds significant promise for the development of molecular-scale electronic devices. Recent years have witnessed a rapidly growing interest in understanding light-matter interactions in illuminated MJs. These studies have profoundly deepened our knowledge of the structure–property relations of various molecular materials and paved critical pathways towards utilizing single molecules in future optoelectronics applications. In this article, we survey recent progress in investigating light-driven charge transport in MJs, including junctions composed of a single molecule and self-assembled monolayers (SAMs) of molecules, and new opportunities in optical sensing at the single-molecule level. We focus our attention on describing the experimental design, key phenomena, and the underlying mechanisms. Specifically, topics presented include light-assisted charge transport, photoswitch, and photoemission in MJs. Emerging Raman sensing in MJs is also discussed. Finally, outstanding challenges are explored, and future perspectives in the field are provided.
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5
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Saxena SK, Tefashe UM, Supur M, McCreery RL. Evaluation of Carbon Based Molecular Junctions as Practical Photosensors. ACS Sens 2021; 6:513-522. [PMID: 33315386 DOI: 10.1021/acssensors.0c02183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular junctions with partially transparent top contacts permit monitoring photocurrents as probes of transport mechanism and potentially could act as photosensors with characteristics determined by the molecular layer inside the device. Previously reported molecular junctions containing nitroazobenzene (NAB) oligomers and oligomers of two different aromatic molecules in bilayers were evaluated for sensitivity, dark signal, responsivity, and limits of detection, in order to determine the device parameters which have the largest effects on photodetection performance. The long-range transport of photogenerated charge carriers permits the use of molecular layers thick enough to absorb a large fraction of the light incident on the layer. Thick layers also reduce the dark current and its associated noise, thus improving the limit of detection to a few nanowatts on a detector area of 0.00125 cm2. Since the photocurrents have much lower activation energy than dark currents do, lowering the detector temperature significantly improves the limit of detection, although the present experiments were limited by environmental and instrumentation noise rather than detector noise. The highest specific detectivity (D*) for the current molecular devices was 3 × 107 cm s1/2 /W (∼109, if only shot noise is considered) at 407 nm in a carbon/NAB/carbon junction with a molecular layer thickness of 28 nm. Although this is in the low end of the 106-1012 range for commonly used photodetectors, improvements in device design based on the current results should increase D* by 3-4 orders of magnitude, while preserving the wavelength selectivity and tunability associated with molecular absorbers. In addition, operation outside the 300-1000 nm range of silicon detectors and very low dark currents may be possible with molecular junctions.
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Affiliation(s)
- Shailendra K. Saxena
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta T6G 2G2, Canada
| | - Ushula M. Tefashe
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta T6G 2G2, Canada
| | - Mustafa Supur
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta T6G 2G2, Canada
| | - Richard L. McCreery
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta T6G 2G2, Canada
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6
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Cohen G, Galperin M. Green’s function methods for single molecule junctions. J Chem Phys 2020; 152:090901. [DOI: 10.1063/1.5145210] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Guy Cohen
- The Raymond and Beverley Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
- School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michael Galperin
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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7
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Sachan P, Mondal PC. Versatile electrochemical approaches towards the fabrication of molecular electronic devices. Analyst 2020; 145:1563-1582. [DOI: 10.1039/c9an01948k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We highlight state-of-the-art electrochemical approaches for diazonium electroreduction on various electrodes that may be suitable for flexible molecular electronic junctions.
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Affiliation(s)
- Pradeep Sachan
- Department of Chemistry
- Indian Institute of Technology
- Kanpur
- India
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8
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Van Dyck C, Bergren AJ, Mukundan V, Fereiro JA, DiLabio GA. Extent of conjugation in diazonium-derived layers in molecular junction devices determined by experiment and modelling. Phys Chem Chem Phys 2019; 21:16762-16770. [PMID: 31328202 DOI: 10.1039/c9cp03509e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
This paper shows that molecular layers grown using diazonium chemistry on carbon surfaces have properties indicative of the presence of a variety of structural motifs. Molecular layers grown with aromatic monomers with thickness between 1 and ∼15 nm display optical absorption spectra with significant broadening but no change in band gap or onsets of absorption as a function of layer thickness. This suggests that there is no extended conjugation in these layers, contrary to the conclusions of previous work. Density-functional theory modelling of the non-conjugated versions of the constituent aromatic monomers reveals that the experimental trends in optical spectra can be recovered, thereby establishing limits to the degree of conjugation and the nature of the order of as-grown molecular layers. We conclude that the absence of both shifts in band gap and changes in absorption onset is a consequence of resonant conjugation within the layers being less than 1.5 monomer units, and that film disorder is the main origin of the optical spectra. These findings have important implications for understanding charge transport mechanisms in molecular junction devices, as the layers cannot be expected to behave as ideal, resonantly conjugated films, but should be viewed as a collection of mixed nonresonantly- and resonantly-conjugated monomers.
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Affiliation(s)
- Colin Van Dyck
- Nanotechnology Research Centre, National Research Council of Canada, 11427 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada.
| | - Adam Johan Bergren
- Nanotechnology Research Centre, National Research Council of Canada, 11427 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada.
| | - Vineetha Mukundan
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jerry A Fereiro
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Gino A DiLabio
- Department of Chemistry, The University of British Columbia, 3247 University Way, Kelowna, British Columbia V1V 1V7, Canada. and Faculty of Management, The University of British Columbia, 1137 Alumni Ave, Kelowna, British Columbia V1V 1V7, Canada
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9
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Du W, Han Y, Hu H, Chu HS, Annadata HV, Wang T, Tomczak N, Nijhuis CA. Directional Excitation of Surface Plasmon Polaritons via Molecular Through-Bond Tunneling across Double-Barrier Tunnel Junctions. NANO LETTERS 2019; 19:4634-4640. [PMID: 31184489 DOI: 10.1021/acs.nanolett.9b01665] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Directional excitation of surface plasmon polaritons (SPPs) by electrical means is important for the integration of plasmonics with molecular electronics or steering signals toward other components. We report electrically driven SPP sources based on quantum mechanical tunneling across molecular double-barrier junctions, where the tunneling pathway is defined by the molecules' chemical structure as well as by their tilt angle with respect to the surface normal. Self-assembled monolayers of S(CH2)nBPh (BPh = biphenyl, n = 1-7) on Au, where the alkyl chain and the BPh units define two distinct tunnel barriers in series, were used to demonstrate and control the geometrical effects. The tilt angle of the BPh unit with respect to the surface normal depends on the value of n, and is 45° when n is even and 23° when n is odd. The tilt angle of the alkyl chain is fixed at 30° and independent of n. For values of n = 1-3, SPPs are directionally launched via directional tunneling through the BPh units. For values of n > 3, tunneling along the alkyl chain dominates the SPP excitation. Molecular level control of directionally launching SPPs is achieved without requiring additional on-chip optical elements, such as antennas, or external elements, such as light sources. Using the molecular tunneling junctions, we provide the first direct experimental demonstration of molecular double-barrier tunneling junctions.
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Affiliation(s)
- Wei Du
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Yingmei Han
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Hongting Hu
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Hong-Son Chu
- Department of Electronics and Photonics, Institute of High Performance Computing , A*STAR (Agency for Science, Technology and Research) , 1 Fusionopolis Way, #16-16 Connexis , 138632 Singapore
| | - Harshini V Annadata
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Tao Wang
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Nikodem Tomczak
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
- Institute of Materials Research and Engineering , A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis , 138634 Singapore
| | - Christian A Nijhuis
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
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10
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Miwa K, Najarian AM, McCreery RL, Galperin M. Hubbard Nonequilibrium Green's Function Analysis of Photocurrent in Nitroazobenzene Molecular Junction. J Phys Chem Lett 2019; 10:1550-1557. [PMID: 30879300 DOI: 10.1021/acs.jpclett.9b00270] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present a combined experimental and theoretical study of photoinduced current in molecular junctions consisting of monolayers of nitroazobenzene oligomers chemisorbed on carbon surfaces and illuminated by ultraviolet-visible light through a transparent electrode. Experimentally observed dependence of the photocurrent on light frequency, temperature, and monolayer thickness is analyzed within first-principles simulations employing the Hubbard nonequilibrium Green's function diagrammatic technique. We reproduce qualitatively correct behavior and discuss mechanisms leading to the characteristic behavior of dark and photoinduced currents in response to changes in bias, frequency of radiation, temperature, and thickness of molecular layer.
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Affiliation(s)
- Kuniyuki Miwa
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92034 , United States
| | | | | | - Michael Galperin
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92034 , United States
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11
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Najarian AM, McCreery RL. Long-Range Activationless Photostimulated Charge Transport in Symmetric Molecular Junctions. ACS NANO 2019; 13:867-877. [PMID: 30604970 DOI: 10.1021/acsnano.8b08662] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Molecular electronic junctions consisting of nitroazobenzene oligomers covalently bonded to a conducting carbon surface using an established "all-carbon" device design were illuminated with UV-vis light through a partially transparent top electrode. Monitoring junction conductance with a DC bias imposed permitted observation of photocurrents while varying the incident wavelength, light intensity, molecular layer thickness, and temperature. The photocurrent spectrum tracked the in situ absorption spectrum of nitroazobenzene, increased linearly with light intensity, and depended exponentially on applied bias. The electronic characteristics of the photocurrent differed dramatically from those of the same device in the dark, with orders of magnitude higher conductance and very weak attenuation with molecular layer thickness (β = 0.14 nm-1 for thickness above 5 nm). The temperature dependence of the photocurrent was opposite that of the dark current, with a 35% decrease in conductance between 80 and 450 K, while the dark current increased by a factor of 4.5 over the same range. The photocurrent was similar to the dark current for thin molecular layers but greatly exceeded the dark current for low bias and thick molecular layers. We conclude that the light and dark mechanisms are additive, with photoexcited carriers transported without thermal activation for a thickness range of 5-10 nm. The inverse temperature dependence is likely due to scattering or recombination events, both of which increase with temperature and in turn decrease the photocurrent. Photostimulated resonant transport potentially widens the breadth of conceivable molecular electronic devices and may have immediate value for wavelength-specific photodetection.
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Affiliation(s)
| | - Richard L McCreery
- Department of Chemistry , University of Alberta , Edmonton , Canada T6G 2R3
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12
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Xu JX, Hu J, Zhang D. Quantification of Material Fluorescence and Light Scattering Cross Sections Using Ratiometric Bandwidth-Varied Polarized Resonance Synchronous Spectroscopy. Anal Chem 2018; 90:7406-7414. [DOI: 10.1021/acs.analchem.8b00847] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Joanna Xiuzhu Xu
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Juan Hu
- Department of Mathematical Sciences, DePaul University, Chicago, Illinois 60604, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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13
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James DD, Bayat A, Smith SR, Lacroix JC, McCreery RL. Nanometric building blocks for robust multifunctional molecular junctions. NANOSCALE HORIZONS 2018; 3:45-52. [PMID: 32254109 DOI: 10.1039/c7nh00109f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Much of the motivation for developing molecular electronic devices is the prospect of achieving novel electronic functions by varying molecular structure. We describe a "building block" approach for molecular junctions resulting in one, two or three nanometer-thick molecular layers in a commercially proven junction design. A single layer of anthraquinone between carbon electrodes provides a tunnel device with applications in electronic music, and a second layer of a thiophene derivative yields a molecular rectifier with quite different audio characteristics. A third layer of lithium benzoate produces a redox-active device with possible applications in non-volatile memory devices or on-chip energy storage. The building block approach forms a basis for "rational design" of electronic functions, in which layers of varying structure produce distinct and desirable electronic behaviours.
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Affiliation(s)
- David D James
- National Institute for Nanotechnology, University of Alberta, 11421 Saskatchewan Dr Edmonton, AB T6G 2M9, Canada.
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14
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Morteza Najarian A, Chen R, Balla RJ, Amemiya S, McCreery RL. Ultraflat, Pristine, and Robust Carbon Electrode for Fast Electron-Transfer Kinetics. Anal Chem 2017; 89:13532-13540. [PMID: 29132207 DOI: 10.1021/acs.analchem.7b03903] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electron-beam (e-beam) deposition of carbon on a gold substrate yields a very flat (0.43 nm of root-mean-square roughness), amorphous carbon film consisting of a mixture of sp2- and sp3-hybridized carbon with sufficient conductivity to avoid ohmic potential error. E-beam carbon (eC) has attractive properties for conventional electrochemistry, including low background current and sufficient transparency for optical spectroscopy. A layer of KCl deposited by e-beam to the eC surface without breaking vacuum protects the surface from the environment after fabrication until dissolved by an ultrapure electrolyte solution. Nanogap voltammetry using scanning electrochemical microscopy (SECM) permits measurement of heterogeneous standard electron-transfer rate constants (k°) in a clean environment without exposure of the electrode surface to ambient air. The ultraflat eC surface permitted nanogap voltammetry with very thin electrode-to-substrate gaps, thus increasing the diffusion limit for k° measurement to >14 cm/s for a gap of 44 nm. Ferrocene trimethylammonium as the redox mediator exhibited a diffusion-limited k° for the previously KCl-protected eC surface, while k° was 1.45 cm/s for unprotected eC. The k° for Ru(NH3)63+/2+ increased from 1.7 cm/s for unprotected eC to above the measurable limit of 6.9 cm/s for a KCl-protected eC electrode.
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Affiliation(s)
- Amin Morteza Najarian
- Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2R3, Canada.,National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
| | - Ran Chen
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Ryan J Balla
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Richard L McCreery
- Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2R3, Canada.,National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
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15
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Jeong H, Kim D, Xiang D, Lee T. High-Yield Functional Molecular Electronic Devices. ACS NANO 2017; 11:6511-6548. [PMID: 28578582 DOI: 10.1021/acsnano.7b02967] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An ultimate goal of molecular electronics, which seeks to incorporate molecular components into electronic circuit units, is to generate functional molecular electronic devices using individual or ensemble molecules to fulfill the increasing technical demands of the miniaturization of traditional silicon-based electronics. This review article presents a summary of recent efforts to pursue this ultimate aim, covering the development of reliable device platforms for high-yield ensemble molecular junctions and their utilization in functional molecular electronic devices, in which distinctive electronic functionalities are observed due to the functional molecules. In addition, other aspects pertaining to the practical application of molecular devices such as manufacturing compatibility with existing complementary metal-oxide-semiconductor technology, their integration, and flexible device applications are also discussed. These advances may contribute to a deeper understanding of charge transport characteristics through functional molecular junctions and provide a desirable roadmap for future practical molecular electronics applications.
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Affiliation(s)
- Hyunhak Jeong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dongku Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dong Xiang
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
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16
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Supur M, Smith SR, McCreery RL. Characterization of Growth Patterns of Nanoscale Organic Films on Carbon Electrodes by Surface Enhanced Raman Spectroscopy. Anal Chem 2017; 89:6463-6471. [DOI: 10.1021/acs.analchem.7b00362] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Mustafa Supur
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Scott R. Smith
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Richard L. McCreery
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
- National
Institute for Nanotechnology, National Research Council Canada, 11421
Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
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17
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Tefashe UM, Nguyen QV, Lafolet F, Lacroix JC, McCreery RL. Robust Bipolar Light Emission and Charge Transport in Symmetric Molecular Junctions. J Am Chem Soc 2017; 139:7436-7439. [DOI: 10.1021/jacs.7b02563] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Ushula M. Tefashe
- Department
of Chemistry, University of Alberta, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Quyen Van Nguyen
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR
7086 CNRS, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Frederic Lafolet
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR
7086 CNRS, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Jean-Christophe Lacroix
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR
7086 CNRS, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Richard L. McCreery
- Department
of Chemistry, University of Alberta, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
- National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
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18
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Vilan A, Aswal D, Cahen D. Large-Area, Ensemble Molecular Electronics: Motivation and Challenges. Chem Rev 2017; 117:4248-4286. [DOI: 10.1021/acs.chemrev.6b00595] [Citation(s) in RCA: 243] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Ayelet Vilan
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
| | | | - David Cahen
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
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19
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Wang Q, Liu R, Xiang D, Sun M, Zhao Z, Sun L, Mei T, Wu P, Liu H, Guo X, Li ZL, Lee T. Single-Atom Switches and Single-Atom Gaps Using Stretched Metal Nanowires. ACS NANO 2016; 10:9695-9702. [PMID: 27704783 DOI: 10.1021/acsnano.6b05676] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Utilizing individual atoms or molecules as functional units in electronic circuits meets the increasing technical demands for the miniaturization of traditional semiconductor devices. To be of technological interest, these functional devices should be high-yield, consume low amounts of energy, and operate at room temperature. In this study, we developed nanodevices called quantized conductance atomic switches (QCAS) that satisfy these requirements. The QCAS operates by applying a feedback-controlled voltage to a nanoconstriction within a stretched nanowire. We demonstrated that individual metal atoms could be removed from the nanoconstriction and that the removed metal atoms could be refilled into the nanoconstriction, thus yielding a reversible quantized conductance switch. We determined the key parameters for the QCAS between the "on" and "off" states at room temperature under a small operating voltage. By controlling the applied bias voltage, the atoms can be further completely removed from the constriction to break the nanowire, generating single-atom nanogaps. These atomic nanogaps are quite stable under a sweeping voltage and can be readjusted with subangstrom accuracy, thus fulfilling the requirement of both reliability and flexibility for the high-yield fabrication of molecular devices.
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Affiliation(s)
- Qingling Wang
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Ran Liu
- College of Physics and Electronics, Shandong Normal University , Jinan 250014, China
| | - Dong Xiang
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Mingyu Sun
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Zhikai Zhao
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Lu Sun
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Tingting Mei
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Pengfei Wu
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Haitao Liu
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Zong-Liang Li
- College of Physics and Electronics, Shandong Normal University , Jinan 250014, China
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
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20
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Morteza Najarian A, Szeto B, Tefashe UM, McCreery RL. Robust All-Carbon Molecular Junctions on Flexible or Semi-Transparent Substrates Using "Process-Friendly" Fabrication. ACS NANO 2016; 10:8918-8928. [PMID: 27529117 DOI: 10.1021/acsnano.6b04900] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Large area molecular junctions were fabricated on electron-beam deposited carbon (eC) surfaces with molecular layers in the range of 2-5.5 nm between conducting, amorphous carbon contacts. Incorporating eC as an interconnect between Au and the molecular layer improves substrate roughness, prevents electromigration and uses well-known electrochemistry to form a covalent C-C bond to the molecular layer. Au/eC/anthraquinone/eC/Au junctions were fabricated on Si/SiOx with high yield and reproducibility and were unchanged by 10(7) current-voltage cycles and temperatures between 80 and 450 K. Au/eC/AQ/eC/Au devices fabricated on plastic films were unchanged by 10(7) current density vs bias voltage (J-V) cycles and repeated bending of the entire assembled junction. The low sheet resistance of Au/eC substrates permitted junctions with sufficiently transparent electrodes to conduct Raman or UV-vis absorption spectroscopy in either reflection or transmission geometries. Lithographic patterning of Au/eC substrates permitted wafer-scale integration yielding 500 devices on 20 chips on a 100 mm diameter wafer. Collectively, eC on Au provides a platform for fabrication and operation of chemically stable, optically and electrically functional molecules on rigid or flexible materials. The relative ease of processing and the robustness of molecular junctions incorporating eC layers should help address the challenge of economic fabrication of practical, flexible molecular junctions for a potentially wide range of applications.
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Affiliation(s)
- Amin Morteza Najarian
- Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2R3, Canada
- National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
| | - Bryan Szeto
- National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
| | - Ushula M Tefashe
- Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2R3, Canada
- National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
| | - Richard L McCreery
- Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2R3, Canada
- National Institute for Nanotechnology, National Research Council Canada , Edmonton, Alberta T6G 2G2, Canada
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21
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Bayat A, Lacroix JC, McCreery RL. Control of Electronic Symmetry and Rectification through Energy Level Variations in Bilayer Molecular Junctions. J Am Chem Soc 2016; 138:12287-96. [DOI: 10.1021/jacs.6b07499] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Akhtar Bayat
- University of Alberta, 11421 Saskatchewan
Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Jean-Christophe Lacroix
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR
7086 CNRS, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Richard L. McCreery
- University of Alberta, 11421 Saskatchewan
Drive, Edmonton, Alberta T6G 2M9, Canada
- National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
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