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Pitié S, Dappe YJ, Maurel F, Seydou M, Lacroix JC. Marcus Theory and Long-Range Activationless Transport in Molecular Junctions. J Phys Chem Lett 2024; 15:6996-7002. [PMID: 38949503 DOI: 10.1021/acs.jpclett.4c01049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Intrachain transport in molecular junctions (MJs) longer than 5 nm has been modeled within the theoretical framework of Marcus theory. We show that in oligo(bisthienylbenzene)-based MJs, electronic transport involves polarons, localized on three monomers that are close to 4 nm in length. They hop and tunnel between adjacent localized sites with reorganization energies λ close to 400-600 meV and electronic coupling parameters Hab close to λ/2. As a consequence, the activation energy for intrachain transport, given by the equation ΔG* = (λ/4)(1 - 2Hab/λ)2, is close to zero, and transport along the chain is activationless, in agreement with experimental observation. On the contrary, similar calculations on conjugated oligonaphthalenefluoreneimine wires show that Hab is much less than λ/2 and predict that the activation energies for intrachain hopping between adjacent sites, close to λ/4, are ∼115 meV. This work proposes a new perspective for understanding long-range activationless transport in MJs beyond the tunneling regime.
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Affiliation(s)
- Sylvain Pitié
- Université Paris Cité, ITODYS, CNRS UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Yannick J Dappe
- Université Paris-Saclay, CEA Saclay, SPEC, CNRS UMR 3680, 91191 Gif-sur-Yvette Cedex, France
| | - François Maurel
- Université Paris Cité, ITODYS, CNRS UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Mahamadou Seydou
- Université Paris Cité, ITODYS, CNRS UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Jean-Christophe Lacroix
- Université Paris Cité, ITODYS, CNRS UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
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2
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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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3
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Bâldea I. Can tunneling current in molecular junctions be so strongly temperature dependent to challenge a hopping mechanism? Analytical formulas answer this question and provide important insight into large area junctions. Phys Chem Chem Phys 2024; 26:6540-6556. [PMID: 38328878 DOI: 10.1039/d3cp05046g] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Analytical equations like Richardson-Dushman's or Shockley's provided a general, if simplified conceptual background, which was widely accepted in conventional electronics and made a fundamental contribution to advances in the field. In the attempt to develop a (highly desirable, but so far missing) counterpart for molecular electronics, in this work, we deduce a general analytical formula for the tunneling current through molecular junctions mediated by a single level that is valid for any bias voltage and temperature. Starting from this expression, which is exact and obviates cumbersome numerical integration, in the low and high temperature limits we also provide analytical formulas expressing the current in terms of elementary functions. They are accurate for broad model parameter ranges relevant for real molecular junctions. Within this theoretical framework we show that: (i) by varying the temperature, the tunneling current can vary by several orders of magnitude, thus debunking the myth that a strong temperature dependence of the current is evidence for a hopping mechanism, (ii) real molecular junctions can undergo a gradual (Sommerfeld-Arrhenius) transition from a weakly temperature dependent to a strongly ("exponential") temperature dependent current that can be tuned by the applied bias, and (iii) important insight into large area molecular junctions with eutectic gallium indium alloy (EGaIn) top electrodes can be gained. E.g., merely based on transport data, we estimate that the current carrying molecules represent only a fraction of f ≈ 4 × 10-4 out of the total number of molecules in a large area Au-S-(CH2)13-CH3/EGaIn junction.
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Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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4
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Bâldea I. Exact Analytic Formula for Conductance Predicting a Tunable Sommerfeld–Arrhenius Thermal Transition within a Single‐Step Tunneling Mechanism in Molecular Junctions Subject to Mechanical Stretching. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ioan Bâldea
- Theoretical Chemistry Heidelberg University Im Neuenheimer Feld 229 D‐69120 Heidelberg Germany
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5
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Dipolar Noise in Fluorinated Molecular Wires. NANOMATERIALS 2022; 12:nano12081371. [PMID: 35458080 PMCID: PMC9031467 DOI: 10.3390/nano12081371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/09/2022] [Accepted: 04/14/2022] [Indexed: 02/04/2023]
Abstract
We demonstrate a strategy to directly map and quantify the effects of dipole formation on electrical transports and noises in the self-assembled monolayers (SAMs) of molecular wires. In this method, the SAM patterns of fluorinated molecules with dipole moments were prepared on conducting substrates, and a conducting probe in contact-mode atomic force microscopy was utilized to map currents and noises through the probe on the molecular patterns. The maps were analyzed to extract the characteristic parameters of dipolar noises in SAMs, and the results were compared with those of hydrogenated molecular patterns without dipole moments. At rather low bias conditions, the fluorinated molecular junctions exhibited a tunneling conduction and a resistance value comparable to that of the hydrogenated molecules with a six-times-longer length, which was attributed to stronger dipoles formation in fluorinated molecules. Interestingly, conductance (G) in different regions of fluorinated molecular patterns exhibited a strong correlation with a noise power spectral density of SI/I2 like SI/I2 ∝ G-2, which can be explained by enhanced barrier fluctuations produced by the dipoles of fluorinated molecules. Furthermore, we observed that the noise power spectral density of fluorinated molecules showed an anomalous frequency (f) dependence like SI/I2 ∝ 1/f1.7, possibly due to the slowing down of the tunneling of carriers from increased barrier fluctuations. In rather high bias conditions, conductions in both hydrogenated and fluorinated molecules showed a transition from tunneling to thermionic charge transports. Our results provide important insights into the effects of dipoles on mesoscopic transport and resistance-fluctuation in molecules and could have a significant impact on the fundamental understanding and applications in this area.
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6
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Han Y, Nickle C, Maglione MS, Karuppannan SK, Casado‐Montenegro J, Qi D, Chen X, Tadich A, Cowie B, Mas‐Torrent M, Rovira C, Cornil J, Veciana J, del Barco E, Nijhuis CA. Bias-Polarity-Dependent Direct and Inverted Marcus Charge Transport Affecting Rectification in a Redox-Active Molecular Junction. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100055. [PMID: 34145786 PMCID: PMC8292891 DOI: 10.1002/advs.202100055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/25/2021] [Indexed: 05/11/2023]
Abstract
This paper describes the transition from the normal to inverted Marcus region in solid-state tunnel junctions consisting of self-assembled monolayers of benzotetrathiafulvalene (BTTF), and how this transition determines the performance of a molecular diode. Temperature-dependent normalized differential conductance analyses indicate the participation of the HOMO (highest occupied molecular orbital) at large negative bias, which follows typical thermally activated hopping behavior associated with the normal Marcus regime. In contrast, hopping involving the HOMO dominates the mechanism of charge transport at positive bias, yet it is nearly activationless indicating the junction operates in the inverted Marcus region. Thus, within the same junction it is possible to switch between Marcus and inverted Marcus regimes by changing the bias polarity. Consequently, the current only decreases with decreasing temperature at negative bias when hopping is "frozen out," but not at positive bias resulting in a 30-fold increase in the molecular rectification efficiency. These results indicate that the charge transport in the inverted Marcus region is readily accessible in junctions with redox molecules in the weak coupling regime and control over different hopping regimes can be used to improve junction performance.
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Affiliation(s)
- Yingmei Han
- Department of ChemistryNational University of Singapore3 Science Drive 3Singapore117543Singapore
| | - Cameron Nickle
- Department of PhysicsUniversity of Central FloridaOrlandoFL32816USA
| | - Maria Serena Maglione
- Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC)/CIBER‐BBNCampus de la UABBellaterra08193Spain
| | | | - Javier Casado‐Montenegro
- Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC)/CIBER‐BBNCampus de la UABBellaterra08193Spain
| | - Dong‐Chen Qi
- Centre for Materials ScienceSchool of Chemistry and PhysicsQueensland University of TechnologyBrisbaneQueensland4001Australia
| | - Xiaoping Chen
- Department of ChemistryNational University of Singapore3 Science Drive 3Singapore117543Singapore
| | - Anton Tadich
- Australian Synchrotron ClaytonVictoria3168Australia
| | - Bruce Cowie
- Australian Synchrotron ClaytonVictoria3168Australia
| | - Marta Mas‐Torrent
- Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC)/CIBER‐BBNCampus de la UABBellaterra08193Spain
| | - Concepció Rovira
- Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC)/CIBER‐BBNCampus de la UABBellaterra08193Spain
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel MaterialsUniversity of MonsPlace du Parc 20MonsB‐7000Belgium
| | - Jaume Veciana
- Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC)/CIBER‐BBNCampus de la UABBellaterra08193Spain
| | | | - Christian A. Nijhuis
- Department of ChemistryNational University of Singapore3 Science Drive 3Singapore117543Singapore
- Centre for Advanced 2D Materials and Graphene Research CenterNational University of Singapore6 Science Drive 2Singapore117546Singapore
- Hybrid Materials for Opto‐Electronics GroupDepartment of Molecules and MaterialsMESA+ Institute for Nanotechnology and Center for Brain‐Inspired Nano SystemsFaculty of Science and TechnologyUniversity of TwenteP.O. Box 217EnschedeAE 7500The Netherlands
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7
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Chen H, Jiang F, Hu C, Jiao Y, Chen S, Qiu Y, Zhou P, Zhang L, Cai K, Song B, Chen XY, Zhao X, Wasielewski MR, Guo H, Hong W, Stoddart JF. Electron-Catalyzed Dehydrogenation in a Single-Molecule Junction. J Am Chem Soc 2021; 143:8476-8487. [PMID: 34043344 DOI: 10.1021/jacs.1c03141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Investigating how electrons propagate through a single molecule is one of the missions of molecular electronics. Electrons, however, are also efficient catalysts for conducting radical reactions, a property that is often overlooked by chemists. Special attention should be paid to electron catalysis when interpreting single-molecule conductance results for the simple reason that an unexpected reaction mediated or triggered by electrons might take place in the single-molecule junction. Here, we describe a counterintuitive structure-property relationship that molecules, both linear and cyclic, employing a saturated bipyridinium-ethane backbone, display a similar conductance signature when compared to junctions formed with molecules containing conjugated bipyridinium-ethene backbones. We describe an ethane-to-ethene transformation, which proceeds in the single-molecule junction by an electron-catalyzed dehydrogenation. Electrochemically based ensemble experiments and theoretical calculations have revealed that the electrons trigger the redox process, and the electric field promotes the dehydrogenation. This finding not only demonstrates the importance of electron catalysis when interpreting experimental results, but also charts a pathway to gaining more insight into the mechanism of electrocatalytic hydrogen production at the single-molecule level.
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Affiliation(s)
- Hongliang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310021, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China
| | - Feng Jiang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Chen Hu
- Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada
| | - Yang Jiao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Su Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yunyan Qiu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ping Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Long Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Kang Cai
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Bo Song
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xiao-Yang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xingang Zhao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Hong Guo
- Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310021, China.,School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China
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8
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Nguyen QV, Frisbie CD. Hopping Conductance in Molecular Wires Exhibits a Large Heavy-Atom Kinetic Isotope Effect. J Am Chem Soc 2021; 143:2638-2643. [PMID: 33587628 DOI: 10.1021/jacs.0c12244] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We report a large kinetic isotope effect (KIE) for intramolecular charge transport in π-conjugated oligophenyleneimine (OPI) molecules connected to Au electrodes. 13C and 15N substitution on the imine bonds produces a conductance KIE of ∼2.7 per labeled atom in long OPI wires >4 nm in length, far larger than typical heavy-atom KIEs for chemical reactions. In contrast, isotopic labeling in shorter OPI wires <4 nm does not produce a conductance KIE, consistent with a direct tunneling mechanism. Temperature-dependent measurements reveal that conductance for a long 15N-substituted OPI wire is activated, and we propose that the exceptionally large conductance KIEs imply a thermally assisted, through-barrier polaron tunneling mechanism. In general, observation of large conductance KIEs opens up considerable opportunities for understanding microscopic conduction mechanisms in π-conjugated molecules.
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Affiliation(s)
- Quyen Van Nguyen
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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9
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Han Y, Nijhuis CA. Functional Redox-Active Molecular Tunnel Junctions. Chem Asian J 2020; 15:3752-3770. [PMID: 33015998 PMCID: PMC7756406 DOI: 10.1002/asia.202000932] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/29/2020] [Indexed: 01/10/2023]
Abstract
Redox-active molecular junctions have attracted considerable attention because redox-active molecules provide accessible energy levels enabling electronic function at the molecular length scales, such as, rectification, conductance switching, or molecular transistors. Unlike charge transfer in wet electrochemical environments, it is still challenging to understand how redox-processes proceed in solid-state molecular junctions which lack counterions and solvent molecules to stabilize the charge on the molecules. In this minireview, we first introduce molecular junctions based on redox-active molecules and discuss their properties from both a chemistry and nanoelectronics point of view, and then discuss briefly the mechanisms of charge transport in solid-state redox-junctions followed by examples where redox-molecules generate new electronic function. We conclude with challenges that need to be addressed and interesting future directions from a chemical engineering and molecular design perspectives.
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Affiliation(s)
- Yingmei Han
- Department of ChemistryNational University of Singapore3 Science Drive 3Singapore117543Singapore
| | - Christian A. Nijhuis
- Department of ChemistryNational University of Singapore3 Science Drive 3Singapore117543Singapore
- Centre for Advanced 2D Materials and Graphene Research CentreNational University of Singapore6 Science Drive 2Singapore117546Singapore
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10
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Taherinia D. Investigation of the Interfacial Electron Transfer Kinetics in Ferrocene-Terminated Oligophenyleneimine Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12572-12579. [PMID: 32936644 DOI: 10.1021/acs.langmuir.0c02105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this article, the synthesis, characterization, and cyclic voltammetry (CV) measurements are reported for ferrocene-terminated oligophenyleneimine (OPI_Fc) and ferrocene-terminated conjugation-broken oligophenyleneimine (CB-OPI_Fc) self-assembled monolayers (SAMs) in two different electrolytes, namely, 1-ethyl-3-methylimidazolium-bis (trifluoromethyl-sulfonyl) imide (EMITFSI) ionic liquid and tetrabutylammonium hexafluorophosphate (Bu4NPF6) in acetonitrile (0.1 M solution). The SAMs were synthesized on Au surfaces by the sequential imine condensation reactions. CV was used to investigate the kinetics of electron transfer (ET) to the ferrocene, and it was observed that the standard ET rate constant (k0) is a strong function of the electrolyte nature as well as the chemical composition of the SAM. Interestingly, when 0.1 M Bu4NPF6 in acetonitrile was used as the electrolyte, all of the SAMs exhibited quite similar k0 values. However, in the case of the ionic liquid, we found that k0 dramatically varies for each SAM and trends as OPI 6_Fc > CB3-OPI 6_Fc > CB5-OPI 6_Fc > CB3,5-OPI 6_Fc. We also examined the temperature dependence of ET kinetics for OPI 2_Fc, OPI 4_Fc, OPI 8_Fc, CB3-OPI 6_Fc, CB5-OPI 6_Fc, and CB3,5-OPI 6_Fc SAMs in EMITFSI ionic liquid. It was found that the activation energies of the ET in these SAMs are very similar (∼0.2 eV). Moreover, it was observed that ln k0 varies linearly with the molecular length for three SAMs, OPI 2_Fc, OPI 4_Fc, and OPI 8_Fc. These findings suggest that the ET to the ferrocene in OPI_Fc and CB-OPI _Fc SAMs takes place via a direct tunneling mechanism.
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Affiliation(s)
- Davood Taherinia
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Department of Chemistry, Sharif University of Technology, Tehran 11155-9516, Iran
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11
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Shuai Z, Li W, Ren J, Jiang Y, Geng H. Applying Marcus theory to describe the carrier transports in organic semiconductors: Limitations and beyond. J Chem Phys 2020; 153:080902. [PMID: 32872875 DOI: 10.1063/5.0018312] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Marcus theory has been successfully applied to molecular design for organic semiconductors with the aid of quantum chemistry calculations for the molecular parameters: the intermolecular electronic coupling V and the intramolecular charge reorganization energy λ. The assumption behind this is the localized nature of the electronic state for representing the charge carriers, being holes or electrons. As far as the quantitative description of carrier mobility is concerned, the direct application of Marcus semiclassical theory usually led to underestimation of the experimental data. A number of effects going beyond such a semiclassical description will be introduced here, including the quantum nuclear effect, dynamic disorder, and delocalization effects. The recently developed quantum dynamics simulation at the time-dependent density matrix renormalization group theory is briefly discussed. The latter was shown to be a quickly emerging efficient quantum dynamics method for the complex system.
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Affiliation(s)
- Zhigang Shuai
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, 100084 Beijing, People's Republic of China
| | - Weitang Li
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, 100084 Beijing, People's Republic of China
| | - Jiajun Ren
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, 100084 Beijing, People's Republic of China
| | - Yuqian Jiang
- Laboratory for Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Chinese Academy of Sciences, 100084 Beijing, People's Republic of China
| | - Hua Geng
- Department of Chemistry, Capital Normal University, 100048 Beijing, People's Republic of China
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12
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Saxena SK, Tefashe UM, McCreery RL. Photostimulated Near-Resonant Charge Transport over 60 nm in Carbon-Based Molecular Junctions. J Am Chem Soc 2020; 142:15420-15430. [DOI: 10.1021/jacs.0c06764] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shailendra K. Saxena
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Ushula M. Tefashe
- 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
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13
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Han B, Li Y, Ji X, Song X, Ding S, Li B, Khalid H, Zhang Y, Xu X, Tian L, Dong H, Yu X, Hu W. Systematic Modulation of Charge Transport in Molecular Devices through Facile Control of Molecule-Electrode Coupling Using a Double Self-Assembled Monolayer Nanowire Junction. J Am Chem Soc 2020; 142:9708-9717. [PMID: 32362123 DOI: 10.1021/jacs.0c02215] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We report a novel solid-state molecular device structure based on double self-assembled monolayers (D-SAM) incorporated into the suspended nanowire architecture to form a "Au|SAM-1||SAM-2|Au" junction. Using commercially available thiol molecules that are devoid of synthetic difficulty, we constructed a "Au|S-(CH2)6-ferrocene||SAM-2|Au" junction with various lengths and chemical structures of SAM-2 to tune the coupling between the ferrocene conductive molecular orbital and electrode of the junction. Combining low noise and a wide temperature range measurement, we demonstrated systematically modulated conduction depending on the length and chemical nature of SAM-2. Meanwhile, the transport mechanism transition from tunneling to hopping and the intermediate state accompanied by the current fluctuation due to the coexistence of the hopping and tunneling transport channels were observed. Considering the versatility of this solid-state D-SAM in modulating the electrode-molecule interface and electroactive groups, this strategy thus provides a novel facile strategy for tailorable nanoscale charge transport studies and functional molecular devices.
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Affiliation(s)
- Bin Han
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Yao Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Xuan Ji
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Xianneng Song
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Shuaishuai Ding
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Baili Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Hira Khalid
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Yaogang Zhang
- School of Science, Yanshan University, Qinhuangdao 066004, China
| | - Xiaona Xu
- School of Science, Yanshan University, Qinhuangdao 066004, China
| | - Lixian Tian
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xi Yu
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
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14
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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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15
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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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16
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Jiang Y, Geng H, Li W, Shuai Z. Understanding Carrier Transport in Organic Semiconductors: Computation of Charge Mobility Considering Quantum Nuclear Tunneling and Delocalization Effects. J Chem Theory Comput 2019; 15:1477-1491. [DOI: 10.1021/acs.jctc.8b00779] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yuqian Jiang
- Laboratory for Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100084, People’s Republic of China
| | - Hua Geng
- Department of Chemistry, Capital Normal University, Beijing 100048, People’s Republic of China
| | - Weitang Li
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Zhigang Shuai
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China
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17
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Sowa JK, Mol JA, Briggs GAD, Gauger EM. Beyond Marcus theory and the Landauer-Büttiker approach in molecular junctions: A unified framework. J Chem Phys 2018; 149:154112. [DOI: 10.1063/1.5049537] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Jakub K. Sowa
- Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford, United Kingdom
| | - Jan A. Mol
- Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford, United Kingdom
| | - G. Andrew D. Briggs
- Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford, United Kingdom
| | - Erik M. Gauger
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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18
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Ivanov MV, Reid SA, Rathore R. Game of Frontier Orbitals: A View on the Rational Design of Novel Charge-Transfer Materials. J Phys Chem Lett 2018; 9:3978-3986. [PMID: 29952570 DOI: 10.1021/acs.jpclett.8b01093] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Since the first application of frontier molecular orbitals (FMOs) to rationalize stereospecificity of pericyclic reactions, FMOs have remained at the forefront of chemical theory. Yet, the practical application of FMOs in the rational design and synthesis of novel charge transfer materials remains under-appreciated. In this Perspective, we demonstrate that molecular orbital theory is a powerful and universal tool capable of rationalizing the observed redox/optoelectronic properties of various aromatic hydrocarbons in the context of their application as charge-transfer materials. Importantly, the inspection of FMOs can provide instantaneous insight into the interchromophoric electronic coupling and polaron delocalization in polychromophoric assemblies, and therefore is invaluable for the rational design and synthesis of novel materials with tailored properties.
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Affiliation(s)
- Maxim V Ivanov
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
| | - Scott A Reid
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
| | - Rajendra Rathore
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
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19
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Chandra Mondal P, Tefashe UM, McCreery RL. Internal Electric Field Modulation in Molecular Electronic Devices by Atmosphere and Mobile Ions. J Am Chem Soc 2018; 140:7239-7247. [DOI: 10.1021/jacs.8b03228] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
| | - Ushula M. Tefashe
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Richard L. McCreery
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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20
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Supur M, Van Dyck C, Bergren AJ, McCreery RL. Bottom-up, Robust Graphene Ribbon Electronics in All-Carbon Molecular Junctions. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6090-6095. [PMID: 29400435 DOI: 10.1021/acsami.7b19305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Large-area molecular electronic junctions consisting of 5-carbon wide graphene ribbons (GR) with lengths of 2-12 nm between carbon electrodes were fabricated by electrochemical reduction of diazotized 1,8-diaminonaphthalene. Their conductance greatly exceeds that observed for other molecular junctions of similar thicknesses, by a factor of >1 × 104 compared to polyphenylenes and >1 × 107 compared to alkane chains. The remarkable increase of conductance of the GR nanolayer results from (i) uninterrupted planarity of fused-arene structure affording extensive π-electron delocalization and (ii) enhanced electronic coupling of molecular layer with the carbon bottom contact by two-point covalent bonding, in agreement with DFT-based simulations.
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Affiliation(s)
- Mustafa Supur
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Colin Van Dyck
- National Institute for Nanotechnology (NINT), National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Adam J Bergren
- National Institute for Nanotechnology (NINT), National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Richard L McCreery
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
- National Institute for Nanotechnology (NINT), National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
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21
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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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22
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Sangeeth CSS, Jiang L, Nijhuis CA. Bottom-electrode induced defects in self-assembled monolayer (SAM)-based tunnel junctions affect only the SAM resistance, not the contact resistance or SAM capacitance. RSC Adv 2018; 8:19939-19949. [PMID: 35541643 PMCID: PMC9080736 DOI: 10.1039/c8ra01513a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/14/2018] [Indexed: 12/22/2022] Open
Abstract
In large area molecular junctions, defects are always present and can be caused by impurities and/or defects in the electrode materials and/or SAMs, but how they affect the electrical characteristics of junctions has rarely been studied. Usually, junctions are characterized by two-terminal current–voltage measurements where only the total current across the junction is measured, but with these methods one cannot distinguish how the individual components of the junctions are altered by the defects. Here we show that the roughness of the bottom-electrode is a crucial factor in determining the electrical properties of self-assembled monolayer (SAM)-based junctions. We used potentiodynamic impedance spectroscopy to reveal which components of the junctions are altered by defective bottom electrodes because this method allows for direct determination of all components that impede charge transport in the equivalent circuit of the junctions. We intentionally introduced defects via the roughness of the bottom electrode and found that these defects lower the SAM resistance but they do not alter the capacitance of the SAM or the contact resistance of the junction. In other words, defective junctions can be seen as “leaky capacitors” resulting in an underestimation of the SAM resistance of two orders of magnitude. These results help to improve the interpretation of data generated by SAM-based junctions and explain in part the observed large spread of reported tunneling rates for the same molecules measured across different platforms. In large area molecular junctions, defects are always present and can be caused by impurities and/or defects in the electrode materials and/or SAMs, but how they affect the electrical characteristics of junctions has rarely been studied.![]()
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Affiliation(s)
| | - Li Jiang
- Department of Chemistry
- National University of Singapore
- Singapore 117543
- Singapore
| | - Christian A. Nijhuis
- Department of Chemistry
- National University of Singapore
- Singapore 117543
- Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre
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23
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Sowa JK, Mol JA, Briggs GAD, Gauger EM. Environment-assisted quantum transport through single-molecule junctions. Phys Chem Chem Phys 2017; 19:29534-29539. [PMID: 29082390 DOI: 10.1039/c7cp06237k] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Single-molecule electronics has been envisioned as the ultimate goal in the miniaturisation of electronic circuits. While the aim of incorporating single-molecule junctions into modern technology still proves elusive, recent developments in this field have begun to enable experimental investigation of fundamental concepts within the area of chemical physics. One such phenomenon is the concept of environment-assisted quantum transport which has emerged from the investigation of exciton transport in photosynthetic complexes. Here, we study charge transport through a two-site molecular junction coupled to a vibrational environment. We demonstrate that vibrational interactions can significantly enhance the current through specific molecular orbitals. Our study offers a clear pathway towards finding and identifying environment-assisted transport phenomena in charge transport settings.
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Affiliation(s)
- Jakub K Sowa
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
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24
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Advance of Mechanically Controllable Break Junction for Molecular Electronics. Top Curr Chem (Cham) 2017; 375:61. [DOI: 10.1007/s41061-017-0149-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 05/16/2017] [Indexed: 10/19/2022]
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25
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Kim H, Segal D. Controlling charge transport mechanisms in molecular junctions: Distilling thermally induced hopping from coherent-resonant conduction. J Chem Phys 2017; 146:164702. [DOI: 10.1063/1.4981022] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Hyehwang Kim
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Dvira Segal
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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26
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Morteza Najarian A, McCreery RL. Structure Controlled Long-Range Sequential Tunneling in Carbon-Based Molecular Junctions. ACS NANO 2017; 11:3542-3552. [PMID: 28238263 DOI: 10.1021/acsnano.7b00597] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Carbon-based molecular junctions consisting of aromatic oligomers between conducting sp2 hybridized carbon electrodes exhibit structure-dependent current densities (J) when the molecular layer thickness (d) exceeds ∼5 nm. All four of the molecular structures examined exhibit an unusual, nonlinear ln J vs bias voltage (V) dependence which is not expected for conventional coherent tunneling or activated hopping mechanisms. All molecules exhibit a weak temperature dependence, with J increasing typically by a factor of 2 over the range of 200-440 K. Fluorene and anthraquinone show linear plots of ln J vs d with nearly identical J values for the range d = 3-10 nm, despite significant differences in their free-molecule orbital energy levels. The observed current densities for anthraquinone, fluorene, nitroazobenzene, and bis-thienyl benzene for d = 7-10 nm show no correlation with occupied (HOMO) or unoccupied (LUMO) molecular orbital energies, contrary to expectations for transport mechanisms based on the offset between orbital energies and the electrode Fermi level. UV-vis absorption spectroscopy of molecular layers bonded to carbon electrodes revealed internal energy levels of the chemisorbed films and also indicated limited delocalization in the film interior. The observed current densities correlate well with the observed UV-vis absorption maxima for the molecular layers, implying a transport mechanism determined by the HOMO-LUMO energy gap. We conclude that transport in carbon-based aromatic molecular junctions is consistent with multistep tunneling through a barrier defined by the HOMO-LUMO gap, and not by charge transport at the electrode interfaces. In effect, interfacial "injection" at the molecule/electrode interfaces is not rate limiting due to relatively strong electronic coupling, and transport is controlled by the "bulk" properties of the molecular layer interior.
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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 , Ottawa, Ontario 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 , Ottawa, Ontario T6G 2G2, Canada
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27
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Ivanov MV, Chebny VJ, Talipov MR, Rathore R. Poly-p-hydroquinone Ethers: Isoenergetic Molecular Wires with Length-Invariant Oxidation Potentials and Cation Radical Excitation Energies. J Am Chem Soc 2017; 139:4334-4337. [DOI: 10.1021/jacs.7b01226] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maxim V. Ivanov
- Department of Chemistry, Marquette University,
P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
| | - Vincent J. Chebny
- Department of Chemistry, Marquette University,
P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
| | - Marat R. Talipov
- Department of Chemistry, Marquette University,
P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
| | - Rajendra Rathore
- Department of Chemistry, Marquette University,
P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
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28
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Bâldea I. Protocol for disentangling the thermally activated contribution to the tunneling-assisted charge transport. Analytical results and experimental relevance. Phys Chem Chem Phys 2017; 19:11759-11770. [DOI: 10.1039/c7cp01103b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper we present results demonstrating that the charge transport by tunneling in molecular junctions can exhibit a substantial temperature dependence.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie
- Universität Heidelberg
- D-69120 Heidelberg
- Germany
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29
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Balgley R, de Ruiter G, Evmenenko G, Bendikov T, Lahav M, van der Boom ME. Light-Induced Conversion of Chemical Permeability to Enhance Electron and Molecular Transfer in Nanoscale Assemblies. J Am Chem Soc 2016; 138:16398-16406. [DOI: 10.1021/jacs.6b09781] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Renata Balgley
- Department
of Organic Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Graham de Ruiter
- Department
of Organic Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Guennadi Evmenenko
- Department
of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Tatyana Bendikov
- Department
of Chemical Research Support, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Lahav
- Department
of Organic Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Milko E. van der Boom
- Department
of Organic Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
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30
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Sethi S, Das PK, Behera N. The chemistry of aminoferrocene, Fe{(η5-C5H4NH2)(η5-Cp)}: Synthesis, reactivity and applications. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.10.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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31
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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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32
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Sangeeth CSS, Demissie AT, Yuan L, Wang T, Frisbie CD, Nijhuis CA. Comparison of DC and AC Transport in 1.5-7.5 nm Oligophenylene Imine Molecular Wires across Two Junction Platforms: Eutectic Ga-In versus Conducting Probe Atomic Force Microscope Junctions. J Am Chem Soc 2016; 138:7305-14. [PMID: 27172452 DOI: 10.1021/jacs.6b02039] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have utilized DC and AC transport measurements to measure the resistance and capacitance of thin films of conjugated oligophenyleneimine (OPI) molecules ranging from 1.5 to 7.5 nm in length. These films were synthesized on Au surfaces utilizing the imine condensation chemistry between terephthalaldehyde and 1,4-benzenediamine. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy yielded molecular tilt angles of 33-43°. To probe DC and AC transport, we employed Au-S-OPI//GaOx/EGaIn junctions having contact areas of 9.6 × 10(2) μm(2) (10(9) nm(2)) and compared to previously reported DC results on the same OPI system obtained using Au-S-OPI//Au conducting probe atomic force microscopy (CP-AFM) junctions with 50 nm(2) areas. We found that intensive observables agreed very well across the two junction platforms. Specifically, the EGaIn-based junctions showed: (i) a crossover from tunneling to hopping transport at molecular lengths near 4 nm; (ii) activated transport for wires >4 nm in length with an activation energy of 0.245 ± 0.008 eV for OPI-7; (iii) exponential dependence of conductance with molecular length with a decay constant β = 2.84 ± 0.18 nm(-1) (DC) and 2.92 ± 0.13 nm(-1) (AC) in the tunneling regime, and an apparent β = 1.01 ± 0.08 nm(-1) (DC) and 0.99 ± 0.11 nm(-1) (AC) in the hopping regime; (iv) previously unreported dielectric constant of 4.3 ± 0.2 along the OPI wires. However, the absolute resistances of Au-S-OPI//GaOx/EGaIn junctions were approximately 100 times higher than the corresponding CP-AFM junctions due to differences in metal-molecule contact resistances between the two platforms.
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Affiliation(s)
- C S Suchand Sangeeth
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543
| | - Abel T Demissie
- Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Li Yuan
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543
| | - Tao Wang
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543.,Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
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33
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Abstract
Recent advances in electrochemistry and nano- and molecular electronics made it possible to prepare and study molecular species having fractional charges (q ≠ 0, ±1, …) that can be continuously tuned by biases.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie
- Universität Heidelberg
- D-69120 Heidelberg
- Germany
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