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Gu MW, Chen CH. Effects of Electrode Materials on Electron Transport for Single-Molecule Junctions. Int J Mol Sci 2023; 24:ijms24087277. [PMID: 37108439 PMCID: PMC10139062 DOI: 10.3390/ijms24087277] [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: 03/02/2023] [Revised: 04/11/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
The contact at the molecule-electrode interface is a key component for a range of molecule-based devices involving electron transport. An electrode-molecule-electrode configuration is a prototypical testbed for quantitatively studying the underlying physical chemistry. Rather than the molecular side of the interface, this review focuses on examples of electrode materials in the literature. The basic concepts and relevant experimental techniques are introduced.
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Affiliation(s)
- Mong-Wen Gu
- Department of Chemistry and Center for Emerging Materials and Advanced Devices, National Taiwan University, Taipei 10617, Taiwan
| | - Chun-Hsien Chen
- Department of Chemistry and Center for Emerging Materials and Advanced Devices, National Taiwan University, Taipei 10617, Taiwan
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2
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Lv SL, Zeng C, Yu Z, Zheng JF, Wang YH, Shao Y, Zhou XS. Recent Advances in Single-Molecule Sensors Based on STM Break Junction Measurements. BIOSENSORS 2022; 12:bios12080565. [PMID: 35892462 PMCID: PMC9329744 DOI: 10.3390/bios12080565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/20/2022] [Accepted: 07/22/2022] [Indexed: 12/04/2022]
Abstract
Single-molecule recognition and detection with the highest resolution measurement has been one of the ultimate goals in science and engineering. Break junction techniques, originally developed to measure single-molecule conductance, recently have also been proven to have the capacity for the label-free exploration of single-molecule physics and chemistry, which paves a new way for single-molecule detection with high temporal resolution. In this review, we outline the primary advances and potential of the STM break junction technique for qualitative identification and quantitative detection at a single-molecule level. The principles of operation of these single-molecule electrical sensing mainly in three regimes, ion, environmental pH and genetic material detection, are summarized. It clearly proves that the single-molecule electrical measurements with break junction techniques show a promising perspective for designing a simple, label-free and nondestructive electrical sensor with ultrahigh sensitivity and excellent selectivity.
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3
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Li JJ, Chen ZB, Wang YH, Zhou XS, Xie LQ, Shi Z, Liu JX, Yan JW, Mao BW. Single-molecule anisotropic magnetoresistance at room temperature: Influence of molecular structure. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
This article reviews the scope of inorganic cluster compounds interrogated in single-molecule break-junction measurements. This body of work lies at the intersection between the fields of inorganic cluster chemistry and single-molecule electronics, where discrete inorganic cluster molecules are used as the active components in molecular electronic circuitry. We explore the breadth of transition metal and main group cluster compounds that have been studied in single-cluster junctions, largely within the context of scanning tunnelling microscopy break-junction (STM-BJ) measurements. Our discussion centers on how the structure and bonding of inorganic cluster compounds give rise to desirable quantum transport effects such as room-temperature current blockade, sequential tunneling, voltage-gated conductance switching, destructive quantum interference, and high thermoelectric currents.
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Affiliation(s)
- Timothy C Siu
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Joshua Y Wong
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Matthew O Hight
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Timothy A Su
- Department of Chemistry, University of California, Riverside, CA 92521, USA. and Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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5
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Li XM, Wang YH, Seng JW, Zheng JF, Cao R, Shao Y, Chen JZ, Li JF, Zhou XS, Mao BW. z-Piezo Pulse-Modulated STM Break Junction: Toward Single-Molecule Rectifiers with Dissimilar Metal Electrodes. ACS APPLIED MATERIALS & INTERFACES 2021; 13:8656-8663. [PMID: 33587592 DOI: 10.1021/acsami.0c21435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fabricating single-molecule junctions with asymmetric metal electrodes is significant for realizing single-molecule diodes, but it remains a big challenge. Herein, we develop a z-piezo pulse-modulated scanning tunneling microscopy break junction (STM-BJ) technique to construct a robust asymmetric junction with different metal electrodes. The asymmetric Ag/BPY-EE/Au single-molecule junctions exhibit a middle conductance value in between those of the two individual symmetric metal electrode junctions, which is consistent with the order of calculated energy-dependent transmission coefficient T(E) of the asymmetric junctions at EF. Furthermore, the single-molecule conductance of Ag/BPY-EE/Au decreases by about 70% when reversing the bias voltage from 100 to -100 mV, and a clear asymmetric I-V feature at the single-molecule level is observed for these junctions. This rectifying behavior could be ascribed to a different interfacial coupling of molecules at the two end electrodes, which is confirmed by the different displacement of T(E) at the two bias voltages. Other asymmetric junctions exhibit similar rectifying behavior. The current work provides a feasible way to fabricate hybrid junctions based on asymmetric metal electrodes and investigate their electron transport toward the design of molecular rectifiers.
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Affiliation(s)
- Xiao-Mei Li
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Ya-Hao Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Jing-Wen Seng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Ju-Fang Zheng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Rui Cao
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Yong Shao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Jing-Zhe Chen
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Jian-Feng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xiao-Shun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Bing-Wei Mao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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6
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Gao T, Liu Y, Zhang X, Bai J, Hong W. Preparation and Application of Microelectrodes at the Single-Molecule Scale. Chem Asian J 2021; 16:253-260. [PMID: 33378120 DOI: 10.1002/asia.202001372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/28/2020] [Indexed: 11/10/2022]
Abstract
Molecular electronics offers a potential solution for the miniaturization of electronics beyond conventional silicon electronics. A key goal of molecular electronics is to fabricate the single-molecule junction with the functions of electronic units. The term "molecular junction" means a molecular cluster or a single molecule incorporated between two microelectrodes, and electrons are transported across it. The methods of constructing molecular junctions dynamically were developed, such as STM-BJ, AFM-BJ, and MCBJ, providing precise control of the gap and easy measurement of thousands of junctions. Electrodes based on these techniques are commonly called microelectrodes because at least one dimension is on the micron scale. In this manuscript, we summarize the preparation methods of microelectrodes and their application in single-molecule measurements. In addition, we discuss the electrode factor that influences the molecular electrical properties, such as material, curvature radius and cone angle, and further provide a brief prospect of molecular electronics.
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Affiliation(s)
- Tengyang Gao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yuyan Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Xueqing Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jie Bai
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.,Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P. R. China
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7
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Improving Gating Efficiency of Electron Transport through Redox‐Active Molecular Junctions with Conjugated Chains. ChemElectroChem 2020. [DOI: 10.1002/celc.201902076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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He C, Zhang Q, Gao T, Liu C, Chen Z, Zhao C, Zhao C, Nichols RJ, Dappe YJ, Yang L. Charge transport in hybrid platinum/molecule/graphene single molecule junctions. Phys Chem Chem Phys 2020; 22:13498-13504. [PMID: 32530005 DOI: 10.1039/d0cp01774d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The single molecule conductance of hybrid platinum/alkanedithiol/graphene junctions has been investigated with a focus on understanding the influence of employing two very different contact types. We call this an "anti-symmetric" configuration, with the two different contacts here being platinum and graphene, which respectively provide very different electronic coupling to the alkanedithiol bridge. The conductance of these junctions is experimentally investigated by using a non-contact scanning tunneling microscopy (STM) based method called the I(s) technique. These experimental determinations are supported by density functional theory (DFT) calculations. These alkanedithiol bridging molecules conduct electric current through the highest occupied molecular orbital (HOMO), and junctions formed with Pt/graphene electrode pairs are slightly more conductive than those formed with Au/graphene electrodes which we previously investigated. This is consistent with the lower work function of gold than that of platinum. The measured conductance decays exponentially with the length of the molecular bridge with a low tunneling decay constant, which has a similar value for Pt/graphene and Au/graphene electrode pairs, respectively. These new results underline the importance of the coupling asymmetry between the two electrodes, more than the type of the metal electrode itself. Importantly, the tunneling decay constant is much lower than that of alkanedithiols with the symmetrical equivalent, i.e. identical metal electrodes. We attribute this difference to the relatively weak van der Waals coupling at the graphene interface and the strong bond dipole at the Pt-S interface, resulting in a decrease in the potential barrier at the interface.
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Affiliation(s)
- Chunhui He
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China. and Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Qian Zhang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China. and Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Tingwei Gao
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China. and Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Chenguang Liu
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China
| | - Zhenyu Chen
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Cezhou Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China
| | - Chun Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France.
| | - Li Yang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China. and Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
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9
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Wang G, Zeng BF, Zhao SQ, Qian QZ, Hong W, Yang Y. Application of electrochemistry to single-molecule junctions: from construction to modulation. Sci China Chem 2019. [DOI: 10.1007/s11426-019-9523-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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He C, Zhang Q, Fan Y, Zhao C, Zhao C, Ye J, Dappe YJ, Nichols RJ, Yang L. Effect of Asymmetric Anchoring Groups on Electronic Transport in Hybrid Metal/Molecule/Graphene Single Molecule Junctions. Chemphyschem 2019; 20:1830-1836. [PMID: 31108024 DOI: 10.1002/cphc.201900424] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/17/2019] [Indexed: 11/08/2022]
Abstract
A combined experimental and theoretical study on molecular junctions with asymmetry in both the electrode type and in the anchoring group type is presented. A scanning tunnelling microscope is used to create the "asymmetric" Au-S-(CH2 )n-COOH-graphene molecular junctions and determine their conductance. The measurements are combined with electron transport calculations based on density functional theory (DFT) to analyze the electrical conductance and its length attenuation factor from a series of junctions of different molecular length (n). These results show an unexpected trend with a rather high conductance and a smaller attenuation factor for the Au-S-(CH2 )n -COOH-graphene configuration compared to the equivalent junction with the "symmetrical" COOH contacting using the HOOC-(CH2 )n -COOH series. Owing to the effect of the graphene electrode, the attenuation factor is also smaller than the one obtained for Au/Au electrodes. These results are interpreted through the relative molecule/electrode couplings and molecular level alignments as determined with DFT calculations. In an asymmetric junction, the electrical current flows through the less resistive conductance channel, similarly to what is observed in the macroscopic regime.
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Affiliation(s)
- Chunhui He
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China.,Department of Chemistry, University of Liverpool, Liverpool, L697ZD, UK
| | - Qian Zhang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China.,Department of Chemistry, University of Liverpool, Liverpool, L697ZD, UK
| | - Yinqi Fan
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China.,Department of Chemistry, University of Liverpool, Liverpool, L697ZD, UK
| | - Cezhou Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China
| | - Chun Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China
| | - Jingyao Ye
- Department of Inorganic Chemistry, Copenhagen University, Universitetparken 21, Copenhagen, Denmark
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette, Cedex, France
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Liverpool, L697ZD, UK
| | - Li Yang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, 215123, Suzhou, China.,Department of Chemistry, University of Liverpool, Liverpool, L697ZD, UK
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11
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Peng LL, Chen F, Hong ZW, Zheng JF, Fillaud L, Yuan Y, Huang ML, Shao Y, Zhou XS, Chen JZ, Maisonhaute E. Precise tuning of single molecule conductance in an electrochemical environment. NANOSCALE 2018; 10:7026-7032. [PMID: 29611859 DOI: 10.1039/c8nr00625c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Tuning of molecular conductance in a liquid environment is a hot topic in molecular electronics. In this article, we explore a new concept where the Fermi level positions of the metallic ends are varied simply by modifying the electroactive salt concentration in solution. We rely on the electrochemical scanning tunneling microscope break junction method that allows the construction in solution of copper atomic contacts that can be then bridged by single molecules. The experimental conductance evolution is first confronted with an analytical formulation that allows the deduction of the molecule's LUMO position and electronic coupling factors. These parameters are in close agreement with those obtained by independent DFT calculations.
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Affiliation(s)
- L-L Peng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
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12
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Zimbovskaya NA, Nitzan A. Thermally induced charge current through long molecules. J Chem Phys 2018; 148:024303. [DOI: 10.1063/1.5005057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Natalya A. Zimbovskaya
- Department of Physics and Electronics, University of Puerto Rico, Humacao, Puerto Rico 00791, USA
| | - Abraham Nitzan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
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13
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Zhang Q, Tao S, Yi R, He C, Zhao C, Su W, Smogunov A, Dappe YJ, Nichols RJ, Yang L. Symmetry Effects on Attenuation Factors in Graphene-Based Molecular Junctions. J Phys Chem Lett 2017; 8:5987-5992. [PMID: 29178793 DOI: 10.1021/acs.jpclett.7b02822] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The unique structural and electronic characteristics of graphene make it an attractive contact for fundamental single-molecule electrical studies. With this in mind, we have probed here the electrical conductance of a molecular junction based on α,ω-diaminoalkane chains sandwiched between a gold and a graphene electrode. Using an STM based I(s) method combined with density functional theory-based transport calculations, we demonstrate that the resulting attenuation factor turns out to be much lower when compared to the standard molecular junction between two gold electrodes. This effect is attributed to asymmetric coupling of the molecule through strong chemisorption at the gold electrode and weaker van der Waals contact at graphene. Moreover, this asymmetric coupling induces higher conductance than that in the same hybrid metal-graphene molecular junction using standard thiol anchoring groups.
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Affiliation(s)
- Qian Zhang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
| | - Shuhui Tao
- Department of Chemistry, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
| | - Ruowei Yi
- Department of Chemistry, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
| | - Chunhui He
- Department of Chemistry, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
| | - Cezhou Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
| | - Weitao Su
- College of Materials and Environmental Engineering, Hangzhou Dianzi University , 310018 Hangzhou, China
| | - Alexander Smogunov
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette, Cedex, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette, Cedex, France
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
| | - Li Yang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University , 215123 Suzhou, China
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, United Kingdom
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14
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Li H, Su TA, Camarasa‐Gómez M, Hernangómez‐Pérez D, Henn SE, Pokorný V, Caniglia CD, Inkpen MS, Korytár R, Steigerwald ML, Nuckolls C, Evers F, Venkataraman L. Silver Makes Better Electrical Contacts to Thiol‐Terminated Silanes than Gold. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Haixing Li
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Timothy A. Su
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - María Camarasa‐Gómez
- Institute of Theoretical Physics University of Regensburg 93040 Regensburg Germany
| | | | - Simon E. Henn
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Vladislav Pokorný
- Department of Condensed Matter Physics, Faculty of Math and Physics Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
- Institute of Physics The Czech Academy of Sciences Na Slovance 2 18221 Prague 8 Czech Republic
| | | | - Michael S. Inkpen
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Richard Korytár
- Department of Condensed Matter Physics, Faculty of Math and Physics Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | | | - Colin Nuckolls
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Ferdinand Evers
- Institute of Theoretical Physics University of Regensburg 93040 Regensburg Germany
| | - Latha Venkataraman
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
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15
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Li H, Su TA, Camarasa‐Gómez M, Hernangómez‐Pérez D, Henn SE, Pokorný V, Caniglia CD, Inkpen MS, Korytár R, Steigerwald ML, Nuckolls C, Evers F, Venkataraman L. Silver Makes Better Electrical Contacts to Thiol‐Terminated Silanes than Gold. Angew Chem Int Ed Engl 2017; 56:14145-14148. [DOI: 10.1002/anie.201708524] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Haixing Li
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Timothy A. Su
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - María Camarasa‐Gómez
- Institute of Theoretical Physics University of Regensburg 93040 Regensburg Germany
| | | | - Simon E. Henn
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Vladislav Pokorný
- Department of Condensed Matter Physics, Faculty of Math and Physics Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
- Institute of Physics The Czech Academy of Sciences Na Slovance 2 18221 Prague 8 Czech Republic
| | | | - Michael S. Inkpen
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Richard Korytár
- Department of Condensed Matter Physics, Faculty of Math and Physics Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | | | - Colin Nuckolls
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
| | - Ferdinand Evers
- Institute of Theoretical Physics University of Regensburg 93040 Regensburg Germany
| | - Latha Venkataraman
- Department of Applied Physics and Chemistry Columbia University New York NY 10027 USA
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16
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Zimbovskaya NA. Length-dependent Seebeck effect in single-molecule junctions beyond linear response regime. J Chem Phys 2017. [DOI: 10.1063/1.4983130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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17
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Zimbovskaya NA. Communication: Length-dependent thermopower of single-molecule junctions. J Chem Phys 2016; 145:221101. [PMID: 27984881 DOI: 10.1063/1.4972002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In the present work, we theoretically study the length dependence of thermopower of a single-molecule junction with a chain-like molecular bridge of an arbitrary length using a tight-binding model. We analyze conditions bringing a nonlinear growth of the thermopower accompanying the extension of the bridge length. Also, we show that the thermopower may decrease with increasing molecular length provided that the molecular bridge is sufficiently long.
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Affiliation(s)
- Natalya A Zimbovskaya
- Department of Physics and Electronics, University of Puerto Rico, Humacao, Puerto Rico 00791, USA
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18
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Abstract
It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical gating. This has been referred to as to a "single molecule transistor configuration" with the gate voltage being provided by the controllable potential achieved through the electrochemical double layer. It is shown how the electrolyte medium can control such gating, with ionic liquids providing more efficient gate coupling than aqueous electrolytes. Control of the conductance of viologen molecular wires can also be achieved by encapsulating the viologen redox moiety within a molecular cage, thereby controlling its immediate environment. Molecular conductance can also be gated through multiple redox states. This has been shown for the redox moiety pyrrolo-tetrathiafulvalene, which undergoes single molecule electrochemical transistor gating through three redox states in molecular junctions. Charge transport through this junction follows a two-step hopping mechanism, demonstrating the role of the redox center in electron transfer across the molecular bridge. Recent electrolyte gating studies of rigid, conjugated redox-active metal complexes with tailored terpyridine coordinating ligands and anchors are also presented. These aforementioned studies have all been performed with gold electrode contacts. The Account concludes with recent data showing that it is now possible to study single molecule electrochemical gating with nickel electrodes. This opens up new perspectives for studying interfacial charge transfer with a wide variety of other electrode materials including semiconductor electrodes and also points toward future opportunities for coupling molecular spintronics and nanoelectrochemistry.
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Affiliation(s)
- Richard J. Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Simon J. Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
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Zhang Q, Liu L, Tao S, Wang C, Zhao C, González C, Dappe YJ, Nichols RJ, Yang L. Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions. NANO LETTERS 2016; 16:6534-6540. [PMID: 27668518 DOI: 10.1021/acs.nanolett.6b03180] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We have measured the single-molecule conductance of 1,n-alkanedithiol molecular bridges (n = 4, 6, 8, 10, 12) on a graphene substrate using scanning tunneling microscopy (STM)-formed electrical junctions. The conductance values of this homologous series ranged from 2.3 nS (n = 12) to 53 nS (n = 4), with a decay constant βn of 0.40 per methylene (-CH2) group. This result is explained by a combination of density functional theory (DFT) and Keldysh-Green function calculations. The obtained decay, which is much lower than the one obtained for symmetric gold junctions, is related to the weak coupling at the molecule-graphene interface and the electronic structure of graphene. As a consequence, we show that using graphene nonsymmetric junctions and appropriate anchoring groups may lead to a much-lower decay constant and more-conductive molecular junctions at longer lengths.
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Affiliation(s)
- Qian Zhang
- Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K
| | - Longlong Liu
- Department of Chemistry and Chemical Engineering, Chongqing University , Chongqing, 400030, China
| | - Shuhui Tao
- Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K
| | | | | | - César González
- SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay 91191 Gif-sur-Yvette Cedex, France
- Departamento de Electrónica y Tecnología de Computadores, Universidad de Granada , Campus de Fuente Nueva & CITIC, Campus de Aynadamar 18071, Granada, Spain
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K
| | - Li Yang
- Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K
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Liu L, Zhang Q, Tao S, Zhao C, Almutib E, Al-Galiby Q, Bailey SWD, Grace I, Lambert CJ, Du J, Yang L. Charge transport through dicarboxylic-acid-terminated alkanes bound to graphene-gold nanogap electrodes. NANOSCALE 2016; 8:14507-14513. [PMID: 27412865 DOI: 10.1039/c6nr03807g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Graphene-based electrodes are attractive for single-molecule electronics due to their high stability and conductivity and reduced screening compared with metals. In this paper, we use the STM-based matrix isolation I(s) method to measure the performance of graphene in single-molecule junctions with one graphene electrode and one gold electrode. By measuring the length dependence of the electrical conductance of dicarboxylic-acid-terminated alkanes, we find that the transport is consistent with phase-coherent tunneling, but with an attenuation factor of βN = 0.69 per methyl unit, which is lower than the value measured for Au-molecule-Au junctions. Comparison with density-functional-theory calculations of electron transport through graphene-molecule-Au junctions and Au-molecule-Au junctions reveals that this difference is due to the difference in Fermi energies of the two types of junction, relative to the frontier orbitals of the molecules. For most molecules, their electrical conductance in graphene-molecule-Au junctions is higher than that in Au-molecule-Au junctions, which suggests that graphene offers superior electrode performance, when utilizing carboxylic acid anchor groups.
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Affiliation(s)
- Longlong Liu
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, Suzhou, Jiangsu 215123, China.
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Electrochemically assisted mechanically controllable break junction studies on the stacking configurations of oligo(phenylene ethynylene)s molecular junctions. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.03.129] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Nichols RJ, Higgins SJ. Single-Molecule Electronics: Chemical and Analytical Perspectives. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2015; 8:389-417. [PMID: 26048551 DOI: 10.1146/annurev-anchem-071114-040118] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
It is now possible to measure the electrical properties of single molecules using a variety of techniques including scanning probe microcopies and mechanically controlled break junctions. Such measurements can be made across a wide range of environments including ambient conditions, organic liquids, ionic liquids, aqueous solutions, electrolytes, and ultra high vacuum. This has given new insights into charge transport across molecule electrical junctions, and these experimental methods have been complemented with increasingly sophisticated theory. This article reviews progress in single-molecule electronics from a chemical perspective and discusses topics such as the molecule-surface coupling in electrical junctions, chemical control, and supramolecular interactions in junctions and gating charge transport. The article concludes with an outlook regarding chemical analysis based on single-molecule conductance.
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Affiliation(s)
- Richard J Nichols
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, United Kingdom;
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Wang YH, Li DF, Hong ZW, Liang JH, Han D, Zheng JF, Niu ZJ, Mao BW, Zhou XS. Conductance of alkyl-based molecules with one, two and three chains measured by electrochemical STM break junction. Electrochem commun 2014. [DOI: 10.1016/j.elecom.2014.05.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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