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Shin J, Gu K, Yang S, Lee CH, Lee T, Jang YH, Wang G. Correlational Effects of the Molecular-Tilt Configuration and the Intermolecular van der Waals Interaction on the Charge Transport in the Molecular Junction. Nano Lett 2018; 18:4322-4330. [PMID: 29906125 DOI: 10.1021/acs.nanolett.8b01294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Molecular conformation, intermolecular interaction, and electrode-molecule contacts greatly affect charge transport in molecular junctions and interfacial properties of organic devices by controlling the molecular orbital alignment. Here, we statistically investigated the charge transport in molecular junctions containing self-assembled oligophenylene molecules sandwiched between an Au probe tip and graphene according to various tip-loading forces ( FL) that can control the molecular-tilt configuration and the van der Waals (vdW) interactions. In particular, the molecular junctions exhibited two distinct transport regimes according to the FL dependence (i.e., FL-dependent and FL-independent tunneling regimes). In addition, the charge-injection tunneling barriers at the junction interfaces are differently changed when the FL ≤ 20 nN. These features are associated to the correlation effects between the asymmetry-coupling factor (η), the molecular-tilt angle (θ), and the repulsive intermolecular vdW force ( FvdW) on the molecular-tunneling barriers. A more-comprehensive understanding of these charge transport properties was thoroughly developed based on the density functional theory calculations in consideration of the molecular-tilt configuration and the repulsive vdW force between molecules.
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Affiliation(s)
- Jaeho Shin
- KU-KIST Graduate School of Converging Science and Technology , Korea University , 145 Anam-ro , Seongbuk-gu, Seoul 02841 , Republic of Korea
| | - Kyungyeol Gu
- Department of Energy Science and Engineering , DGIST , Daegu 42988 , Republic of Korea
| | - Seunghoon Yang
- KU-KIST Graduate School of Converging Science and Technology , Korea University , 145 Anam-ro , Seongbuk-gu, Seoul 02841 , Republic of Korea
| | - Chul-Ho Lee
- KU-KIST Graduate School of Converging Science and Technology , Korea University , 145 Anam-ro , Seongbuk-gu, Seoul 02841 , Republic of Korea
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics , Seoul National University , Seoul 08826 , Republic of Korea
| | - Yun Hee Jang
- Department of Energy Science and Engineering , DGIST , Daegu 42988 , Republic of Korea
| | - Gunuk Wang
- KU-KIST Graduate School of Converging Science and Technology , Korea University , 145 Anam-ro , Seongbuk-gu, Seoul 02841 , Republic of Korea
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Dasgupta A, Buret M, Cazier N, Mennemanteuil MM, Chacon R, Hammani K, Weeber JC, Arocas J, Markey L, des Francs GC, Uskov A, Smetanin I, Bouhelier A. Electromigrated electrical optical antennas for transducing electrons and photons at the nanoscale. Beilstein J Nanotechnol 2018; 9:1964-1976. [PMID: 30116688 PMCID: PMC6071726 DOI: 10.3762/bjnano.9.187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/28/2018] [Indexed: 05/26/2023]
Abstract
Background: Electrically controlled optical metal antennas are an emerging class of nanodevices enabling a bilateral transduction between electrons and photons. At the heart of the device is a tunnel junction that may either emit light upon injection of electrons or generate an electrical current when excited by a light wave. The current study explores a technological route for producing these functional units based upon the electromigration of metal constrictions. Results: We combine multiple nanofabrication steps to realize in-plane tunneling junctions made of two gold electrodes, separated by a sub-nanometer gap acting as the feedgap of an optical antenna. We electrically characterize the transport properties of the junctions in the light of the Fowler-Nordheim representation and the Simmons model for electron tunneling. We demonstrate light emission from the feedgap upon electron injection and show examples of how this nanoscale light source can be coupled to waveguiding structures. Conclusion: Electromigrated in-plane tunneling optical antennas feature interesting properties with their unique functionality enabling interfacing electrons and photons at the atomic scale and with the same device. This technology may open new routes for device-to-device communication and for interconnecting an electronic control layer to a photonic architecture.
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Affiliation(s)
- Arindam Dasgupta
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Mickaël Buret
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Nicolas Cazier
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Marie-Maxime Mennemanteuil
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Reinaldo Chacon
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Kamal Hammani
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Jean-Claude Weeber
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Juan Arocas
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Laurent Markey
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Gérard Colas des Francs
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
| | - Alexander Uskov
- P. N. Lebedev Physical Institute, Leninsky pr. 53, 119991 Moscow, Russia
- ITMO University, Kronverkskiy pr. 49, 197101 Sankt-Petersburg, Russia
| | - Igor Smetanin
- P. N. Lebedev Physical Institute, Leninsky pr. 53, 119991 Moscow, Russia
| | - Alexandre Bouhelier
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS-UMR 6303, Université Bourgogne Franche-Comté, 21078 Dijon, France
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Xie Z, Bâldea I, Oram S, Smith CE, Frisbie CD. Effect of Heteroatom Substitution on Transport in Alkanedithiol-Based Molecular Tunnel Junctions: Evidence for Universal Behavior. ACS Nano 2017; 11:569-578. [PMID: 27936325 DOI: 10.1021/acsnano.6b06623] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The transport properties of molecular junctions based on alkanedithiols with three different methylene chain lengths were compared with junctions based on similar chains wherein every third -CH2- was replaced with O or S, that is, following the general formula HS(CH2CH2X)nCH2CH2SH, where X = CH2, O, or S and n = 1, 2, or 3. Conducting probe atomic force microscopy revealed that the low bias resistance of the chains increased upon substitution in the order CH2 < O < S. This change in resistance is ascribed to the observed identical trend in contact resistance, Rc, whereas the exponential prefactor β (length sensitivity) was essentially the same for all chains. Using an established, analytical single-level model, we computed the effective energy offset εh (i.e., Fermi level relative to the effective HOMO level) and the electronic coupling strength Γ from the current-voltage (I-V) data. The εh values were only weakly affected by heteroatom substitution, whereas the interface coupling strength Γ varied by over an order of magnitude. Consequently, we ascribe the strong variation in Rc to the systematic change in Γ. Quantum chemical calculations reveal that the HOMO density shifts from the terminal SH groups for the alkanedithiols to the heteroatoms in the substituted chains, which provides a plausible explanation for the marked decrease in Γ for the dithiols with electron-rich heteroatoms. The results indicate that the electronic coupling and thus the resistance of alkanedithiols can be tuned by substitution of even a single atom in the middle of the molecule. Importantly, when appropriately normalized, the experimental I-V curves were accurately simulated over the full bias range (±1.5 V) using the single-level model with no adjustable parameters. The data could be collapsed to a single universal curve predicted by the model, providing clear evidence that the essential physics is captured by this analytical approach and supporting its utility for molecular electronics.
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Affiliation(s)
- Zuoti Xie
- Department of Chemical Engineering and Materials Science and Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Ioan Bâldea
- Theoretische Chemie, Universität Heidelberg , INF 229, D-69120 Heidelberg, Germany
- National Institute of Lasers, Plasma and Radiation Physics, Institute of Space Science , POB MG-23, RO 077125 Bucharest, Romania
| | - Stuart Oram
- Department of Chemical Engineering and Materials Science and Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Christopher E Smith
- Department of Chemical Engineering and Materials Science and Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science and Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
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