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Colin-Molina A, Nematiaram T, Cheung AMH, Troisi A, Frisbie CD. The Conductance Isotope Effect in Oligophenylene Imine Molecular Wires Depends on the Number and Spacing of 13C-Labeled Phenylene Rings. ACS NANO 2024; 18:7444-7454. [PMID: 38411123 DOI: 10.1021/acsnano.3c11327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We report a strong and structurally sensitive 13C intramolecular conductance isotope effect (CIE) for oligophenyleneimine (OPI) molecular wires connected to Au electrodes. Wires were built from Au surfaces beginning with the formation of 4-aminothiophenol self-assembled monolayers (SAMs) followed by subsequent condensation reactions with 13C-labeled terephthalaldehyde and phenylenediamine; in these monomers the phenylene rings were either completely 13C-labeled or the naturally abundant 12C isotopologues. Alternatively, perdeuterated versions of terephthalaldehyde and phenylenediamine were employed to make 2H(D)-labeled OPI wires. For 13C-isotopologues of short OPI wires (<4 nm) in length where the charge transport mechanism is tunneling, there was no measurable effect, i.e., 13C CIE ≈ 1, where CIE is defined as the ratio of labeled and unlabeled wire resistances, i.e., CIE = Rheavy/Rlight. However, for long OPI wires >4 nm, in which the transport mechanism is polaron hopping, a strong 13C CIE = 4-5 was observed. A much weaker inverse CIE < 1 was evident for the longest D-labeled wires. Importantly, the magnitude of the 13C CIE was sensitive to the number and spacing of 13C-labeled rings, i.e., the CIE was structurally sensitive. The structural sensitivity is intriguing because it may be employed to understand polaron hopping mechanisms and charge localization/delocalization in molecular wires. A preliminary theoretical analysis explored several possible explanations for the CIE, but so far a fully satisfactory explanation has not been identified. Nevertheless, the latest results unambiguously demonstrate structural sensitivity of the heavy atom CIE, offering directions for further utilization of this interesting effect.
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Affiliation(s)
- Abraham Colin-Molina
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Tahereh Nematiaram
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G11XL, United Kingdom
| | - Andy Man Hong Cheung
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool, Liverpool L697ZD, United Kingdom
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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2
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Zinelli R, Soni S, Cornelissen JJLM, Michel-Souzy S, Nijhuis CA. Charge Transport across Proteins inside Proteins: Tunneling across Encapsulin Protein Cages and the Effect of Cargo Proteins. Biomolecules 2023; 13:174. [PMID: 36671559 PMCID: PMC9855946 DOI: 10.3390/biom13010174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/05/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Charge transport across proteins can be surprisingly efficient over long distances-so-called long-range tunneling-but it is still unclear as to why and under which conditions (e.g., presence of co-factors, type of cargo) the long-range tunneling regime can be accessed. This paper describes molecular tunneling junctions based on an encapsulin (Enc), which is a large protein cage with a diameter of 24 nm that can be loaded with various types of (small) proteins, also referred to as "cargo". We demonstrate with dynamic light scattering, transmission electron microscopy, and atomic force microscopy that Enc, with and without cargo, can be made stable in solution and immobilized on metal electrodes without aggregation. We investigated the electronic properties of Enc in EGaIn-based tunnel junctions (EGaIn = eutectic alloy of Ga and In that is widely used to contact (bio)molecular monolayers) by measuring the current density for a large range of applied bias of ±2.5 V. The encapsulated cargo has an important effect on the electrical properties of the junctions. The measured current densities are higher for junctions with Enc loaded with redox-active cargo (ferritin-like protein) than those junctions without cargo or redox-inactive cargo (green fluorescent protein). These findings open the door to charge transport studies across complex biomolecular hierarchical structures.
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Affiliation(s)
- Riccardo Zinelli
- Hybrid Materials for Opto-Electronics 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
- Biomolecular NanoTechnology, 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
| | - Saurabh Soni
- Hybrid Materials for Opto-Electronics 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
| | - Jeroen J. L. M. Cornelissen
- Biomolecular NanoTechnology, 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
| | - Sandra Michel-Souzy
- Biomolecular NanoTechnology, 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
| | - Christian A. Nijhuis
- Hybrid Materials for Opto-Electronics 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, P.O. Box 2017, 7500 AE Enschede, The Netherlands
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3
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Large emergent optoelectronic enhancement in molecularly cross-linked gold nanoparticle nanosheets. Commun Chem 2022; 5:103. [PMID: 36698024 PMCID: PMC9814044 DOI: 10.1038/s42004-022-00723-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 08/17/2022] [Indexed: 01/28/2023] Open
Abstract
A central goal in molecular electronics and optoelectronics is to translate tailorable molecular properties to larger materials and to the device level. Here, we present a method to fabricate molecularly cross-linked, self-assembled 2D nanoparticle sheets (X-NS). Our method extends a Langmuir approach of self-assembling gold nanoparticle (NP) arrays at an air-water interface by replacing the liquid sub-phase to an organic solvent to enable cross-linking with organic molecules, and then draining the sub-phase to deposit films. Remarkably, X-NS comprising conjugated oligophenylene dithiol cross-linkers (HS-(C6H4)n-SH, 1 ≤ n ≤ 3) exhibit increasing conductance with molecule length, ~6 orders of magnitude enhancement in UV-Vis extinction coefficients, and photoconductivity with molecule vs. NP contributions varying depending on the excitation wavelength. Finite difference time domain (FDTD) analyses and control measurements indicate that these effects can be modeled provided the local complex dielectric constant is strongly modified upon cross-linking. This suggests quantum hybridization at a molecule-band (q-MB) level. Given the vast number of molecules and nano-building blocks available, X-NS have potential to significantly increase the range of available 2D nanosheets and associated quantum properties.
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4
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Dlugosch JM, Seim H, Bora A, Kamiyama T, Lieberman I, May F, Müller-Plathe F, Nefedov A, Prasad S, Resch S, Saller K, Seim C, Speckbacher M, Voges F, Tornow M, Kirsch P. Conductance Switching in Liquid Crystal-Inspired Self-Assembled Monolayer Junctions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:31044-31053. [PMID: 35776551 DOI: 10.1021/acsami.2c05264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We present the prototype of a ferroelectric tunnel junction (FTJ), which is based on a self-assembled monolayer (SAM) of small, functional molecules. These molecules have a structure similar to those of liquid crystals, and they are embedded between two solid-state electrodes. The SAM, which is deposited through a short sequence of simple fabrication steps, is extremely thin (3.4 ± 0.5 nm) and highly uniform. The functionality of the FTJ is ingrained in the chemical structure of the SAM components: a conformationally flexible dipole that can be reversibly reoriented in an electrical field. Thus, the SAM acts as an electrically switchable tunnel barrier. Fabricated stacks of Al/Al2O3/SAM/Pb/Ag with such a polar SAM show pronounced hysteretic, reversible conductance switching at voltages in the range of ±2-3 V, with a conductance ratio of the low and the high resistive states of up to 100. The switching mechanism is analyzed using a combination of quantum chemical, molecular dynamics, and tunneling resistance calculation methods. In contrast to more common, inorganic material-based FTJs, our approach using SAMs of small organic molecules allows for a high degree of functional complexity and diversity to be integrated by synthetic standard methods, while keeping the actual device fabrication process robust and simple. We expect that this technology can be further developed toward a level that would then allow its application in the field of information storage and processing, in particular for in-memory and neuromorphic computing architectures.
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Affiliation(s)
- Julian M Dlugosch
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Henning Seim
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Achyut Bora
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Takuya Kamiyama
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Itai Lieberman
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Falk May
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Alexei Nefedov
- Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Saurav Prasad
- Eduard-Zintl Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Sebastian Resch
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Kai Saller
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Christian Seim
- Xploraytion GmbH, Bismarckstraße 10-12, 10625 Berlin, Germany
| | - Maximilian Speckbacher
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Frank Voges
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Marc Tornow
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
- Fraunhofer Research Institution for Microsystems and Solid State Technologies (EMFT), Hansastraße 27d, 80686 München, Germany
| | - Peer Kirsch
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
- Institute of Materials Science, Technical University of Darmstadt, Alarich-Weiss-Straße 2, 64297 Darmstadt, Germany
- Freiburg Materials Research Center (FMF), Albert Ludwig University Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
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5
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Carlotti M, Soni S, Kovalchuk A, Kumar S, Hofmann S, Chiechi RC. Empirical Parameter to Compare Molecule-Electrode Interfaces in Large-Area Molecular Junctions. ACS PHYSICAL CHEMISTRY AU 2022; 2:179-190. [PMID: 35637782 PMCID: PMC9136952 DOI: 10.1021/acsphyschemau.1c00029] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 12/03/2022]
Abstract
![]()
This paper describes
a simple model for comparing the degree of
electronic coupling between molecules and electrodes across different
large-area molecular junctions. The resulting coupling parameter can
be obtained directly from current–voltage data or extracted
from published data without fitting. We demonstrate the generalizability
of this model by comparing over 40 different junctions comprising
different molecules and measured by different laboratories. The results
agree with existing models, reflect differences in mechanisms of charge
transport and rectification, and are predictive in cases where experimental
limitations preclude more sophisticated modeling. We also synthesized
a series of conjugated molecular wires, in which embedded dipoles
are varied systematically and at both molecule–electrode interfaces.
The resulting current–voltage characteristics vary in nonintuitive
ways that are not captured by existing models, but which produce trends
using our simple model, providing insights that are otherwise difficult
or impossible to explain. The utility of our model is its demonstrative
generalizability, which is why simple observables like tunneling decay
coefficients remain so widely used in molecular electronics despite
the existence of much more sophisticated models. Our model is complementary,
giving insights into molecule–electrode coupling across series
of molecules that can guide synthetic chemists in the design of new
molecular motifs, particularly in the context of devices comprising
large-area molecular junctions.
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Affiliation(s)
- Marco Carlotti
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Saurabh Soni
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andrii Kovalchuk
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Sumit Kumar
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Stephan Hofmann
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Ryan C Chiechi
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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6
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Ashkarran AA, Hosseini A, Loloee R, Perry G, Lee KB, Lund M, Ejtehadi MR, Mahmoudi M. Conformation- and phosphorylation-dependent electron tunnelling across self-assembled monolayers of tau peptides. J Colloid Interface Sci 2022; 606:2038-2050. [PMID: 34749450 DOI: 10.1016/j.jcis.2021.09.185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 09/17/2021] [Accepted: 09/28/2021] [Indexed: 10/20/2022]
Abstract
We report on charge transport across self-assembled monolayers (SAMs) of short tau peptides by probing the electron tunneling rates and quantum mechanical simulation. We measured the electron tunneling rates across SAMs of carboxyl-terminated linker molecules (C6H12O2S) and short cis-tau (CT) and trans-tau (TT) peptides, supported on template-stripped gold (AuTS) bottom electrode, with Eutectic Gallium-Indium (EGaIn)(EGaIn) top electrode. Measurements of the current density across thousands of AuTS/linker/tau//Ga2O3/EGaIn single-molecule junctions show that the tunneling current across CT peptide is one order of magnitude lower than that of TT peptide. Quantum mechanical simulation demonstrated a wider energy bandgap of the CT peptide, as compared to the TT peptide, which causes a reduction in its electron tunneling current. Our findings also revealed the critical role of phosphorylation in altering the charge transport characteristics of short peptides; more specifically, we found that the presence of phosphate groups can reduce the energy band gap in tau peptides and alter their electrical properties. Our results suggest that conformational and phosphorylation of short peptides (e.g., tau) can significantly change their charge transport characteristics and energy levels.
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Affiliation(s)
- Ali Akbar Ashkarran
- Precision Health Program and Department of Radiology, Michigan State University, East Lansing, MI 48824, USA.
| | - Atiyeh Hosseini
- Division of Theoretical Chemistry, Lund University, Lund, Sweden; Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
| | - Reza Loloee
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
| | - George Perry
- Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA
| | - Ki-Bum Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Mikael Lund
- Division of Theoretical Chemistry, Lund University, Lund, Sweden.
| | | | - Morteza Mahmoudi
- Precision Health Program and Department of Radiology, Michigan State University, East Lansing, MI 48824, USA
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7
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Tian L, Martine E, Yu X, Hu W. Amine-Anchored Aromatic Self-Assembled Monolayer Junction: Structure and Electric Transport Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12223-12233. [PMID: 34606290 DOI: 10.1021/acs.langmuir.1c02194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We studied the structure and transport properties of aromatic amine self-assembled monolayers (NH2-SAMs) on an Au surface. The oligophenylene and oligoacene amines with variable lengths can form a densely packed and uniform monolayer under proper assembly conditions. Molecular junctions incorporating an eutectic Ga-In (EGaIn) top electrode were used to characterize the charge transport properties of the amine monolayer. The current density J of the junction decreases exponentially with the molecular length (d), as J = J0 exp(-βd), which is a sign of tunneling transport, with indistinguishable values of J0 and β for NH2-SAMs of oligophenylene and oligoacene, indicating a similar molecule-electrode contact and tunneling barrier for two groups of molecules. Compared with the oligophenylene and oligoacene molecules with thiol (SH) as the anchor group, a similar β value (∼0.35 Å-1) of the aromatic NH2-SAM suggests a similar tunneling barrier, while a lower (by 2 orders of magnitude) injection current J0 is attributed to lower electronic coupling Γ of the amine group with the electrode. These observations are further supported by single-level tunneling model fitting. Our study here demonstrates the NH2-SAMs can work as an effective active layer for molecular junctions, and provide key physical parameters for the charge transport, paving the road for their applications in functional devices.
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Affiliation(s)
- Lixian Tian
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Esther Martine
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Xi Yu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
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8
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Chen X, Kretz B, Adoah F, Nickle C, Chi X, Yu X, Del Barco E, Thompson D, Egger DA, Nijhuis CA. A single atom change turns insulating saturated wires into molecular conductors. Nat Commun 2021; 12:3432. [PMID: 34103489 PMCID: PMC8187423 DOI: 10.1038/s41467-021-23528-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 04/30/2021] [Indexed: 11/09/2022] Open
Abstract
We present an efficient strategy to modulate tunnelling in molecular junctions by changing the tunnelling decay coefficient, β, by terminal-atom substitution which avoids altering the molecular backbone. By varying X = H, F, Cl, Br, I in junctions with S(CH2)(10-18)X, current densities (J) increase >4 orders of magnitude, creating molecular conductors via reduction of β from 0.75 to 0.25 Å−1. Impedance measurements show tripled dielectric constants (εr) with X = I, reduced HOMO-LUMO gaps and tunnelling-barrier heights, and 5-times reduced contact resistance. These effects alone cannot explain the large change in β. Density-functional theory shows highly localized, X-dependent potential drops at the S(CH2)nX//electrode interface that modifies the tunnelling barrier shape. Commonly-used tunnelling models neglect localized potential drops and changes in εr. Here, we demonstrate experimentally that \documentclass[12pt]{minimal}
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\begin{document}$$\beta \propto 1/\sqrt{{\varepsilon }_{r}}$$\end{document}β∝1/εr, suggesting highly-polarizable terminal-atoms act as charge traps and highlighting the need for new charge transport models that account for dielectric effects in molecular tunnelling junctions. In molecular junctions, where a molecule is placed between two electrodes, the current passed decays exponentially as a function of length. Here, Chen et al. show that this exponentially attenuation can be controlled by changing a single atom at the end of the molecular wire.
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Affiliation(s)
- Xiaoping Chen
- Department of Chemistry, National University of Singapore, Singapore, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
| | - Bernhard Kretz
- Department of Physics, Technical University of Munich, Garching, Germany
| | - Francis Adoah
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Cameron Nickle
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Xiao Chi
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, Singapore
| | - Enrique Del Barco
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Damien Thompson
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - David A Egger
- Department of Physics, Technical University of Munich, Garching, Germany.
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore, Singapore, Singapore. .,Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore. .,Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands.
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9
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Lee HJ, Cho SJ, Kang H, He X, Yoon HJ. Achieving Ultralow, Zero, and Inverted Tunneling Attenuation Coefficients in Molecular Wires with Extended Conjugation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005711. [PMID: 33543557 DOI: 10.1002/smll.202005711] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/22/2020] [Indexed: 06/12/2023]
Abstract
Molecular tunnel junctions are organic devices miniaturized to the molecular scale. They serve as a versatile toolbox that can systematically examine charge transport behaviors at the atomic level. The electrical conductance of the molecular wire that bridges the two electrodes in a junction is significantly influenced by its chemical structure, and an intrinsically poor conductance is a major barrier for practical applications toward integrating individual molecules into electronic circuitry. Therefore, highly conjugated molecular wires are attractive as active components for the next-generation electronic devices, owing to the narrow highest occupied molecular orbital-lowest occupied molecular orbital gaps provided by their extended π-building blocks. This article aims to highlight the significance of highly conductive molecular wires in molecular electronics, the structures of which are inspired from conductive organic polymers, and presents a body of discussion on molecular wires exhibiting ultralow, zero, or inverted attenuation of tunneling probability at different lengths, along with future directions.
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Affiliation(s)
- Hyun Ju Lee
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Soo Jin Cho
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Hungu Kang
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Xin He
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
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10
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Karuppannan SK, Martín-Rodríguez A, Ruiz E, Harding P, Harding DJ, Yu X, Tadich A, Cowie B, Qi D, Nijhuis CA. Room temperature conductance switching in a molecular iron(iii) spin crossover junction. Chem Sci 2020; 12:2381-2388. [PMID: 34164002 PMCID: PMC8179334 DOI: 10.1039/d0sc04555a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction. The junction is constructed from [FeIII(qsal-I)2]NTf2 (qsal-I = 4-iodo-2-[(8-quinolylimino)methyl]phenolate) molecules self-assembled on graphene surfaces with conductance switching of one order of magnitude associated with the high and low spin states of the SCO complex. Normalized conductance analysis of the current–voltage characteristics as a function of temperature reveals that charge transport across the SCO molecule is dominated by coherent tunnelling. Temperature-dependent X-ray absorption spectroscopy and density functional theory confirm the SCO complex retains its SCO functionality on the surface implying that van der Waals molecule—electrode interfaces provide a good trade-off between junction stability while retaining SCO switching capability. These results provide new insights and may aid in the design of other types of molecular devices based on SCO compounds. Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction.![]()
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Affiliation(s)
- Senthil Kumar Karuppannan
- Department of Chemistry, National University of Singapore 3 Science Drive Singapore 117543 Singapore
| | - Alejandro Martín-Rodríguez
- Departament de Química Inorgànica, Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Eliseo Ruiz
- Departament de Química Inorgànica, Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Phimphaka Harding
- Functional Materials and Nanotechnology Center of Excellence, Walailak University Thasala Nakhon Si Thammarat 80160 Thailand
| | - David J Harding
- Functional Materials and Nanotechnology Center of Excellence, Walailak University Thasala Nakhon Si Thammarat 80160 Thailand
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore 5 Research Link Singapore 117603 Singapore
| | - Anton Tadich
- Australian Synchrotron Clayton Victoria 3168 Australia
| | - Bruce Cowie
- School of Chemistry and Physics, Queensland University of Technology Brisbane Queensland 4001 Australia
| | - Dongchen Qi
- School of Chemistry and Physics, Queensland University of Technology Brisbane Queensland 4001 Australia
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore 3 Science Drive Singapore 117543 Singapore .,Centre for Advanced 2D Materials & Graphene Research, National University of Singapore 6 Science Drive 2 Singapore 117546 Singapore
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11
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Park S, Kang S, Yoon HJ. Power Factor of One Molecule Thick Films and Length Dependence. ACS CENTRAL SCIENCE 2019; 5:1975-1982. [PMID: 31893227 PMCID: PMC6936095 DOI: 10.1021/acscentsci.9b01042] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Indexed: 06/07/2023]
Abstract
There is a rapidly increasing interest in organic thin film thermoelectrics. However, the power factor of one molecule thick organic film, the self-assembled monolayer (SAM), has not yet been determined. This study describes the experimental determination of the power factor in SAMs and its length dependence at an atomic level. As a proof-of-concept, SAMs composed of n-alkanethiolates and oligophenylenethiolates of different lengths are focused. These SAMs were electrically and thermoelectrically characterized on an identical junction platform using a liquid metal top-electrode, allowing the straightforward estimation of the power factor of the monolayers. The results show that the power factor of the alkyl SAMs ranged from 2.0 × 10-8 to 8.0 × 10-12 μW m-1 K-2 and exhibited significant negative length dependence, whereas the conductivity and thermopower of the conjugated SAMs are the two opposing factors that balance the power factor upon an increase in molecular length, exhibiting a maximum power factor of 3.6 × 10-8 μW m-1 K-2. Once correction factors about the ratio of effective contact area to geometrical contact area are considered, the values of power factors can be increased by several orders of magnitude. With a newly derived parametric semiempirical model describing the length dependence of the power factor, it is investigated that one molecule thick films thinner than 10 nm composed of thiophene units can yield power factors rivaling those of famed organic thermoelectric materials based on poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate (PEDOT/PSS) and polyaniline/graphene/double-walled carbon nanotube. Furthermore, how the transition of the transport regime from tunneling to hopping as molecules become long affects power factors is examined.
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Herrmann C. Electronic Communication as a Transferable Property of Molecular Bridges? J Phys Chem A 2019; 123:10205-10223. [PMID: 31380640 DOI: 10.1021/acs.jpca.9b05618] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Electronic communication through molecular bridges is important for different types of experiments, such as single-molecule conductance, electron transfer, superexchange spin coupling, and intramolecular singlet fission. In many instances, the chemical structure of the bridge determines how the two parts it is connecting communicate, and does so in ways that are transferable between these different manifestations (for example, high conductance often correlates with strong antiferromagnetic spin coupling, and low conductance due to destructive quantum interference correlates with ferromagnetic coupling). Defining electronic communication as a transferable property of the bridge can help transfer knowledge between these different areas of research. Examples and limits of such transferability are discussed here, along with some possible directions for future research, such as employing spin-coupled and mixed-valence systems as structurally well-controlled proxies for understanding molecular conductance and for validating first-principles theoretical methodologies, building conceptual understanding for the growing experimental work on intramolecular singlet fission, and developing measures for the transferability of electronic communication as a bridge property.
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Affiliation(s)
- Carmen Herrmann
- Department of Chemistry , University of Hamburg , Martin-Luther-King-Platz 6 , Hamburg 20146 , Germany
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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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Carlotti M, Soni S, Qiu X, Sauter E, Zharnikov M, Chiechi RC. Systematic experimental study of quantum interference effects in anthraquinoid molecular wires. NANOSCALE ADVANCES 2019; 1:2018-2028. [PMID: 31304460 PMCID: PMC6592160 DOI: 10.1039/c8na00223a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/07/2019] [Indexed: 05/17/2023]
Abstract
In order to translate molecular properties in molecular-electronic devices, it is necessary to create design principles that can be used to achieve better structure-function control oriented toward device fabrication. In molecular tunneling junctions, cross-conjugation tends to give rise to destructive quantum interference effects that can be tuned by changing the electronic properties of the molecules. We performed a systematic study of the tunneling charge-transport properties of a series of compounds characterized by an identical cross-conjugated anthraquinoid molecular skeleton but bearing different substituents at the 9 and 10 positions that affect the energies and localization of their frontier orbitals. We compared the experimental results across three different experimental platforms in both single-molecule and large-area junctions and found a general agreement. Combined with theoretical models, these results separate the intrinsic properties of the molecules from platform-specific effects. This work is a step towards explicit synthetic control over tunneling charge transport targeted at specific functionality in (proto-)devices.
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Affiliation(s)
- Marco Carlotti
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Saurabh Soni
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Xinkai Qiu
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Eric Sauter
- Applied Physical Chemistry , Heidelberg University , Im Neuenheier Feld 253 , Heidelberg 69120 , Germany
| | - Michael Zharnikov
- Applied Physical Chemistry , Heidelberg University , Im Neuenheier Feld 253 , Heidelberg 69120 , Germany
| | - Ryan C Chiechi
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
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Pütt R, Qiu X, Kozłowski P, Gildenast H, Linnenberg O, Zahn S, Chiechi RC, Monakhov KY. Self-assembled monolayers of polyoxovanadates with phthalocyaninato lanthanide moieties on gold surfaces. Chem Commun (Camb) 2019; 55:13554-13557. [DOI: 10.1039/c9cc06852j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Conductive self-assembled monolayers of host–guest vanadium–oxo cages functionalised with phthalocyaninato YbIII moieties have been formed on gold surfaces.
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Affiliation(s)
- Ricarda Pütt
- Institut für Anorganische Chemie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Xinkai Qiu
- Stratingh Institute for Chemistry & Zernike Institute for Advanced Materials
- University of Groningen
- Groningen 9747 AG
- The Netherlands
| | - Piotr Kozłowski
- Faculty of Physics
- Adam Mickiewicz University in Poznań
- ul. Uniwersytetu Poznańskiego 2
- 61-614 Poznań
- Poland
| | - Hans Gildenast
- Institut für Anorganische Chemie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Oliver Linnenberg
- Institut für Anorganische Chemie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Stefan Zahn
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
| | - Ryan C. Chiechi
- Stratingh Institute for Chemistry & Zernike Institute for Advanced Materials
- University of Groningen
- Groningen 9747 AG
- The Netherlands
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Xie Z, Bâldea I, Haugstad G, Daniel Frisbie C. Mechanical Deformation Distinguishes Tunneling Pathways in Molecular Junctions. J Am Chem Soc 2018; 141:497-504. [DOI: 10.1021/jacs.8b11248] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
| | - Ioan Bâldea
- Theoretische Chemie, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany
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