1
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Yasini P, Shepard S, Smeu M, Borguet E. Modulation of Charge Transport through Single Molecules Induced by Solvent-Stabilized Intramolecular Charge Transfer. J Phys Chem B 2023; 127:9771-9780. [PMID: 37933172 DOI: 10.1021/acs.jpcb.3c03576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
The modulation of charge transport through single molecules can be established by using the intrinsic characteristics of molecules and the physical properties of their environment. Therefore, the impact of the solvent on the electronic properties of molecules in the junction and their charge transport behavior are of great interest. Here, for the first time, we focused on charge transport through dimethylaminobenzonitrile (DMABN). This molecule shows unique behavior, specifically noticeable electronic structure modulations in bulk solvents, e.g., dual fluorescence in a polar environment. Using the scanning tunneling microscopy break junction (STM-BJ) technique, we find an order of magnitude increase in conductance along with a second conductance value in polar solvents over nonpolar solvents. Inspired by the twisted intramolecular charge transfer (TICT) explanation of the famous dual fluorescence of DMABN in polar solvents, we hypothesize stabilization of twisted DMABN molecules in the junction in more polar solvents. Ab initio molecular dynamics (AIMD) simulations using density functional theory (DFT) show that DMABN can twist in the junction and have a larger dipole moment compared to planar DMABN junction geometries, supporting the hypothesis. The nonequilibrium Green's function with the DFT approach (NEGF-DFT) is used to calculate the conductance throughout the AIMD trajectory, finding a significant change in the frontier orbitals and transmission function at large internal twisting angles, which can explain the dual conductance in polar solvents in STM-BJ experiments.
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Affiliation(s)
- Parisa Yasini
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Stuart Shepard
- Department of Physics, Binghamton University, Binghamton, New York 13902, United States
| | - Manuel Smeu
- Department of Physics, Binghamton University, Binghamton, New York 13902, United States
| | - Eric Borguet
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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2
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Highly insulating alkane rings with destructive σ-interference. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1341-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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3
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Nováková Lachmanová Š, Kolivoška V, Šebera J, Gasior J, Mészáros G, Dupeyre G, Lainé PP, Hromadová M. Environmental Control of Single-Molecule Junction Evolution and Conductance: A Case Study of Expanded Pyridinium Wiring. Angew Chem Int Ed Engl 2021; 60:4732-4739. [PMID: 33205862 PMCID: PMC7986070 DOI: 10.1002/anie.202013882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/13/2020] [Indexed: 02/03/2023]
Abstract
Environmental control of single-molecule junction evolution and conductance was demonstrated for expanded pyridinium molecules by scanning tunneling microscopy break junction method and interpreted by quantum transport calculations including solvent molecules explicitly. Fully extended and highly conducting molecular junctions prevail in water environment as opposed to short and less conducting junctions formed in non-solvating mesitylene. A theoretical approach correctly models single-molecule conductance values considering the experimental junction length. Most pronounced difference in the molecular junction formation and conductance was identified for a molecule with the highest stabilization energy on the gold substrate confirming the importance of molecule-electrode interactions. Presented concept of tuning conductance through molecule-electrode interactions in the solvent-driven junctions can be used in the development of new molecular electronic devices.
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Affiliation(s)
- Štěpánka Nováková Lachmanová
- Department of Electrochemistry at NanoscaleJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesDolejškova 3182 23Prague 8Czech Republic
| | - Viliam Kolivoška
- Department of Electrochemistry at NanoscaleJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesDolejškova 3182 23Prague 8Czech Republic
| | - Jakub Šebera
- Department of Electrochemistry at NanoscaleJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesDolejškova 3182 23Prague 8Czech Republic
| | - Jindřich Gasior
- Department of Electrochemistry at NanoscaleJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesDolejškova 3182 23Prague 8Czech Republic
| | - Gábor Mészáros
- Research Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok krt. 21117BudapestHungary
| | | | | | - Magdaléna Hromadová
- Department of Electrochemistry at NanoscaleJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesDolejškova 3182 23Prague 8Czech Republic
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4
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Nováková Lachmanová Š, Kolivoška V, Šebera J, Gasior J, Mészáros G, Dupeyre G, Lainé PP, Hromadová M. Environmental Control of Single‐Molecule Junction Evolution and Conductance: A Case Study of Expanded Pyridinium Wiring. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Štěpánka Nováková Lachmanová
- Department of Electrochemistry at Nanoscale J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague 8 Czech Republic
| | - Viliam Kolivoška
- Department of Electrochemistry at Nanoscale J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague 8 Czech Republic
| | - Jakub Šebera
- Department of Electrochemistry at Nanoscale J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague 8 Czech Republic
| | - Jindřich Gasior
- Department of Electrochemistry at Nanoscale J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague 8 Czech Republic
| | - Gábor Mészáros
- Research Centre for Natural Sciences Hungarian Academy of Sciences Magyar tudósok krt. 2 1117 Budapest Hungary
| | | | | | - Magdaléna Hromadová
- Department of Electrochemistry at Nanoscale J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague 8 Czech Republic
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5
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Gelin MF, Kosov DS. A model for dynamical solvent control of molecular junction electronic properties. J Chem Phys 2021; 154:044107. [PMID: 33514101 DOI: 10.1063/5.0039328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Experimental measurements of electron transport properties of molecular junctions are often performed in solvents. Solvent-molecule coupling and physical properties of the solvent can be used as the external stimulus to control the electric current through a molecule. In this paper, we propose a model that includes dynamical effects of solvent-molecule interaction in non-equilibrium Green's function calculations of the electric current. The solvent is considered as a macroscopic dipole moment that reorients stochastically and interacts with the electrons tunneling through the molecular junction. The Keldysh-Kadanoff-Baym equations for electronic Green's functions are solved in the time domain with subsequent averaging over random realizations of rotational variables using the Furutsu-Novikov method for the exact closure of infinite hierarchy of stochastic correlation functions. The developed theory requires the use of wideband approximation as well as classical treatment of solvent degrees of freedom. The theory is applied to a model molecular junction. It is demonstrated that not only electrostatic interaction between molecular junction and solvent but also solvent viscosity can be used to control electrical properties of the junction. Alignment of the rotating dipole moment breaks the particle-hole symmetry of the transmission favoring either hole or electron transport channels depending upon the aligning potential.
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Affiliation(s)
- Maxim F Gelin
- School of Sciences, Hangzhou Dianzi University, 310018 Hangzhou, China
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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6
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Chen Y, Huang L, Chen H, Chen Z, Zhang H, Xiao Z, Hong W. Towards Responsive
Single‐Molecule
Device. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202000420] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Yaorong Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Longfeng Huang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Hang Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Zhixin Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Hewei Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Zongyuan Xiao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
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7
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Ivie JA, Bamberger ND, Parida KN, Shepard S, Dyer D, Saraiva-Souza A, Himmelhuber R, McGrath DV, Smeu M, Monti OLA. Correlated Energy-Level Alignment Effects Determine Substituent-Tuned Single-Molecule Conductance. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4267-4277. [PMID: 33438990 DOI: 10.1021/acsami.0c19404] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The rational design of single-molecule electrical components requires a deep and predictive understanding of structure-function relationships. Here, we explore the relationship between chemical substituents and the conductance of metal-single-molecule-metal junctions, using functionalized oligophenylenevinylenes as a model system. Using a combination of mechanically controlled break-junction experiments and various levels of theory including non-equilibrium Green's functions, we demonstrate that the connection between gas-phase molecular electronic structure and in-junction molecular conductance is complicated by the involvement of multiple mutually correlated and opposing effects that contribute to energy-level alignment in the junction. We propose that these opposing correlations represent powerful new "design principles" because their physical origins make them broadly applicable, and they are capable of predicting the direction and relative magnitude of observed conductance trends. In particular, we show that they are consistent with the observed conductance variability not just within our own experimental results but also within disparate molecular series reported in the literature and, crucially, with the trend in variability across these molecular series, which previous simple models fail to explain. The design principles introduced here can therefore aid in both screening and suggesting novel design strategies for maximizing conductance tunability in single-molecule systems.
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Affiliation(s)
- Jeffrey A Ivie
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Nathan D Bamberger
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Keshaba N Parida
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Stuart Shepard
- Department of Physics, Binghamton University-SUNY, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Dylan Dyer
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Aldilene Saraiva-Souza
- Departamento de Física, Universidade Federal do Maranhão, São Luís, Massachusetts 65080-805, Brazil
| | - Roland Himmelhuber
- College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721, United States
| | - Dominic V McGrath
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Manuel Smeu
- Department of Physics, Binghamton University-SUNY, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Oliver L A Monti
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
- Department of Physics, University of Arizona, 1118 E. Fourth Street, Tucson, Arizona 85721, United States
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8
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Li J, Shen P, Zhen S, Tang C, Ye Y, Zhou D, Hong W, Zhao Z, Tang BZ. Mechanical single-molecule potentiometers with large switching factors from ortho-pentaphenylene foldamers. Nat Commun 2021; 12:167. [PMID: 33420002 PMCID: PMC7794330 DOI: 10.1038/s41467-020-20311-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/24/2020] [Indexed: 11/22/2022] Open
Abstract
Molecular potentiometers that can indicate displacement-conductance relationship, and predict and control molecular conductance are of significant importance but rarely developed. Herein, single-molecule potentiometers are designed based on ortho-pentaphenylene. The ortho-pentaphenylene derivatives with anchoring groups adopt multiple folded conformers and undergo conformational interconversion in solutions. Solvent-sensitive multiple conductance originating from different conformers is recorded by scanning tunneling microscopy break junction technique. These pseudo-elastic folded molecules can be stretched and compressed by mechanical force along with a variable conductance by up to two orders of magnitude, providing an impressively higher switching factor (114) than the reported values (ca. 1~25). The multichannel conductance governed by through-space and through-bond conducting pathways is rationalized as the charge transport mechanism for the folded ortho-pentaphenylene derivatives. These findings shed light on exploring robust single-molecule potentiometers based on helical structures, and are conducive to fundamental understanding of charge transport in higher-order helical molecules.
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Affiliation(s)
- Jinshi Li
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, 510640, Guangzhou, China
| | - Pingchuan Shen
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, 510640, Guangzhou, China
| | - Shijie Zhen
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, 510640, Guangzhou, China
| | - Chun Tang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Yiling Ye
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Dahai Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China.
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, 510640, Guangzhou, China.
| | - Ben Zhong Tang
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, 510640, Guangzhou, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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9
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Tang Z, Hou S, Wu Q, Tan Z, Zheng J, Li R, Liu J, Yang Y, Sadeghi H, Shi J, Grace I, Lambert CJ, Hong W. Solvent-molecule interaction induced gating of charge transport through single-molecule junctions. Sci Bull (Beijing) 2020; 65:944-950. [PMID: 36747427 DOI: 10.1016/j.scib.2020.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 01/08/2023]
Abstract
To explore solvent gating of single-molecule electrical conductance due to solvent-molecule interactions, charge transport through single-molecule junctions with different anchoring groups in various solvent environments was measured by using the mechanically controllable break junction technique. We found that the conductance of single-molecule junctions can be tuned by nearly an order of magnitude by varying the polarity of solvent. Furthermore, gating efficiency due to solvent-molecule interactions was found to be dependent on the choice of the anchor group. Theoretical calculations revealed that the polar solvent shifted the molecular-orbital energies, based on the coupling strength of the anchor groups. For weakly coupled molecular junctions, the polar solvent-molecule interaction was observed to reduce the energy gap between the molecular orbital and the Fermi level of the electrode and shifted the molecular orbitals. This resulted in a more significant gating effect than that of the strongly coupled molecules. This study suggested that solvent-molecule interaction can significantly affect the charge transport through single-molecule junctions.
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Affiliation(s)
- Zheng Tang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Songjun Hou
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Qingqing Wu
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Zhibing Tan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jueting Zheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Ruihao Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yang Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Hatef Sadeghi
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Jia Shi
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Iain Grace
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
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10
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Zhou Q, Cho Y, Yang S, Weiss EA, Berkelbach TC, Darancet P. Large Band Edge Tunability in Colloidal Nanoplatelets. NANO LETTERS 2019; 19:7124-7129. [PMID: 31545615 DOI: 10.1021/acs.nanolett.9b02645] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the impact of organic surface ligands on the electronic structure and electronic band edge energies of quasi-two-dimensional (2D) colloidal cadmium selenide nanoplatelets (NPLs) using density functional theory. We show how control of the ligand and ligand-NPL interface dipoles results in large band edge energy shifts, over a range of 5 eV for common organic ligands with a minor effect on the NPL band gaps. Using a model self-energy to account for the dielectric contrast and an effective mass model of the excitons, we show that the band edge tunability of NPLs together with the strong dependence of the optical band gap on NPL thickness can lead to favorable photochemical and optoelectronic properties.
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Affiliation(s)
- Qunfei Zhou
- Materials Research Science and Engineering Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Yeongsu Cho
- Department of Chemistry and James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
| | - Shenyuan Yang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , Beijing 100083 , China
- Center for Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Emily A Weiss
- Department of Chemistry and Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Timothy C Berkelbach
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
- Center for Computational Quantum Physics , Flatiron Institute , New York , New York 10010 , United States
| | - Pierre Darancet
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
- Northwestern Argonne Institute of Science and Engineering , Evanston , Illinois 60208 , United States
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11
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Yang G, Sangtarash S, Liu Z, Li X, Sadeghi H, Tan Z, Li R, Zheng J, Dong X, Liu J, Yang Y, Shi J, Xiao Z, Zhang G, Lambert C, Hong W, Zhang D. Protonation tuning of quantum interference in azulene-type single-molecule junctions. Chem Sci 2017; 8:7505-7509. [PMID: 29163904 PMCID: PMC5676185 DOI: 10.1039/c7sc01014a] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 09/07/2017] [Indexed: 11/21/2022] Open
Abstract
The protonation of azulene cores offers significant conductance tuning in single-molecule junctions with quantum interference.
The protonation of azulene derivatives with quantum interference effects is studied by the conductance measurements of single-molecule junctions. Three azulene derivatives with different connectivities are synthesized and reacted with trifluoroacetic acid to form the protonated states. It is found that the protonated azulene molecular junctions produce more than one order of magnitude higher conductance than the neutral states, while the molecules with destructive interference show more significant changes. These experimental observations are supported by our recently-developed parameter free theory of connectivity, which suggests that the largest conductance change occurs when destructive interference near the Fermi energy in the neutral state is alleviated by protonation.
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Affiliation(s)
- Guogang Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Sara Sangtarash
- Department of Physics , Lancaster University , Lancaster LA1 4YB , UK .
| | - Zitong Liu
- Organic Solids Laboratory , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China . ;
| | - Xiaohui Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Hatef Sadeghi
- Department of Physics , Lancaster University , Lancaster LA1 4YB , UK .
| | - Zhibing Tan
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Ruihao Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Jueting Zheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Xiaobiao Dong
- Organic Solids Laboratory , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China . ;
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Yang Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Jia Shi
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Zongyuan Xiao
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Guanxin Zhang
- Organic Solids Laboratory , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China . ;
| | - Colin Lambert
- Department of Physics , Lancaster University , Lancaster LA1 4YB , UK .
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces , iChEM , Department of Chemical and Biochemical Engineering , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China .
| | - Deqing Zhang
- Organic Solids Laboratory , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China . ;
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12
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Abstract
Employing self-interaction corrected density functional theory combined with the non-equilibrium Green’s function method, we study the quantum transport through molecules with different numbers of phenyl (donor) and pyrimidinyl (acceptor) rings in order to evaluate the effects of the molecular composition on the transport properties. Excellent agreement with the results of recent experiments addressing the rectification behavior of molecular junctions is obtained, which demonstrates the potential of quantum transport simulations for designing high performance junctions by tuning the molecular specifications.
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13
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Al-Owaedi OA, Bock S, Milan DC, Oerthel MC, Inkpen MS, Yufit DS, Sobolev AN, Long NJ, Albrecht T, Higgins SJ, Bryce MR, Nichols RJ, Lambert CJ, Low PJ. Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions. NANOSCALE 2017; 9:9902-9912. [PMID: 28678257 DOI: 10.1039/c7nr01829k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Metal complexes are receiving increased attention as molecular wires in fundamental studies of the transport properties of metal|molecule|metal junctions. In this context we report the single-molecule conductance of a systematic series of d8 square-planar platinum(ii) trans-bis(alkynyl) complexes with terminal trimethylsilylethynyl (C[triple bond, length as m-dash]CSiMe3) contacting groups, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H4C[triple bond, length as m-dash]CSiMe3}2(PR3)2 (R = Ph or Et), using a combination of scanning tunneling microscopy (STM) experiments in solution and theoretical calculations using density functional theory and non-equilibrium Green's function formalism. The measured conductance values of the complexes (ca. 3-5 × 10-5G0) are commensurate with similarly structured all-organic oligo(phenylene ethynylene) and oligo(yne) compounds. Based on conductance and break-off distance data, we demonstrate that a PPh3 supporting ligand in the platinum complexes can provide an alternative contact point for the STM tip in the molecular junctions, orthogonal to the terminal C[triple bond, length as m-dash]CSiMe3 group. The attachment of hexyloxy side chains to the diethynylbenzene ligands, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H2(Ohex)2C[triple bond, length as m-dash]CSiMe3}2(PPh3)2 (Ohex = OC6H13), hinders contact of the STM tip to the PPh3 groups and effectively insulates the molecule, allowing the conductance through the full length of the backbone to be reliably measured. The use of trialkylphosphine (PEt3), rather than triarylphosphine (PPh3), ancillary ligands at platinum also eliminates these orthogonal contacts. These results have significant implications for the future design of organometallic complexes for studies in molecular junctions.
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Affiliation(s)
- Oday A Al-Owaedi
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK. and Department of Laser Physics, Women Faculty of Science, Babylon University, Hilla, Iraq
| | - Sören Bock
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
| | - David C Milan
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | | | - Michael S Inkpen
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Dmitry S Yufit
- Department of Chemistry, Durham University, South Rd, Durham, DH1 3LE, UK
| | - Alexandre N Sobolev
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia and Centre for Microscopy Characterization and Analysis, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
| | - Nicholas J Long
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Tim Albrecht
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Martin R Bryce
- Department of Chemistry, Durham University, South Rd, Durham, DH1 3LE, UK
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Colin J Lambert
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK.
| | - Paul J Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
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14
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Van Dyck C, Marks TJ, Ratner MA. Chain Length Dependence of the Dielectric Constant and Polarizability in Conjugated Organic Thin Films. ACS NANO 2017; 11:5970-5981. [PMID: 28575578 DOI: 10.1021/acsnano.7b01807] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dielectric materials are ubiquitous in optics, electronics, and materials science. Recently, there have been new efforts to characterize the dielectric performance of thin films composed of molecular assemblies. In this context, we investigate here the relationship between the polarizability of the constituent molecules and the film dielectric constant, using periodic density functional theory (DFT) calculations, for polyyne and saturated alkane chains. In particular, we explore the implication of the superlinear chain length dependence of the polarizability, a specific feature of conjugated molecules. We show and explain from DFT calculations and a simple depolarization model that this superlinearity is attenuated by the collective polarization. However, it is not completely suppressed. This confers a very high sensitivity of the dielectric constant to the thin film thickness. This latter can increase by a factor of 3-4 at reasonable coverages, by extending the molecular length. This significantly limits the decline of the thin film capacitance with the film thickness. Therefore, the conventional fit of the capacitance versus thickness is not appropriate to determine the dielectric constant of the film. Finally, we show that the failures of semilocal approximations of the exchange-correlation functional lead to a very significant overestimation of this effect.
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Affiliation(s)
- Colin Van Dyck
- Department of Chemistry and the Materials Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Mark A Ratner
- Department of Chemistry and the Materials Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
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15
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Li WQ, Huang B, Huang ML, Peng LL, Hong ZW, Zheng JF, Chen WB, Li JF, Zhou XS. Detecting Electron Transport of Amino Acids by Using Conductance Measurement. SENSORS 2017; 17:s17040811. [PMID: 28394265 PMCID: PMC5422172 DOI: 10.3390/s17040811] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/05/2017] [Accepted: 04/06/2017] [Indexed: 12/14/2022]
Abstract
The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10−1.85 G0 (1095 nS) and 10−3.7 G0 (15.5 nS), while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH2–C–COOH is the primary means of electron transport in the molecular junction of aspartic acid and glutamic acid. However, NH2–C–COOH is not the primary means of electron transport in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide) bond for the methionine junction. The current work reveals the important role of the anchoring group in the electron transport in different amino acids junctions.
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Affiliation(s)
- Wei-Qiong Li
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
| | - Bing Huang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
| | - Miao-Ling Huang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
| | - Lin-Lu Peng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
| | - Ze-Wen Hong
- 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.
| | - Wen-Bo Chen
- Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China.
| | - Jian-Feng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, 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.
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16
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Low JZ, Capozzi B, Cui J, Wei S, Venkataraman L, Campos LM. Tuning the polarity of charge carriers using electron deficient thiophenes. Chem Sci 2017. [PMID: 28626554 PMCID: PMC5465950 DOI: 10.1039/c6sc05283e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed with these systems. Through these measurements, we find that increasing the electron affinity of thiophene derivatives, within a family of pentamers, changes the polarity of the charge carriers systematically from holes to electrons, with some systems even showing mid-gap transport characteristics.
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Affiliation(s)
- Jonathan Z Low
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
| | - Brian Capozzi
- Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Jing Cui
- Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Sujun Wei
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
| | - Latha Venkataraman
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA . .,Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Luis M Campos
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
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17
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Fung ED, Adak O, Lovat G, Scarabelli D, Venkataraman L. Too Hot for Photon-Assisted Transport: Hot-Electrons Dominate Conductance Enhancement in Illuminated Single-Molecule Junctions. NANO LETTERS 2017; 17:1255-1261. [PMID: 28112947 DOI: 10.1021/acs.nanolett.6b05091] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4'-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20-40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4'-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.
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Affiliation(s)
- E-Dean Fung
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Olgun Adak
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Giacomo Lovat
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Diego Scarabelli
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
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18
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Groß L, Herrmann C. GenLocDip: A Generalized Program to Calculate and Visualize Local Electric Dipole Moments. J Comput Chem 2016; 37:2324-34. [PMID: 27416879 DOI: 10.1002/jcc.24420] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 04/30/2016] [Accepted: 05/06/2016] [Indexed: 11/09/2022]
Abstract
Local dipole moments (i.e., dipole moments of atomic or molecular subsystems) are essential for understanding various phenomena in nanoscience, such as solvent effects on the conductance of single molecules in break junctions or the interaction between the tip and the adsorbate in atomic force microscopy. We introduce GenLocDip, a program for calculating and visualizing local dipole moments of molecular subsystems. GenLocDip currently uses the Atoms-In-Molecules (AIM) partitioning scheme and is interfaced to various AIM programs. This enables postprocessing of a variety of electronic structure output formats including cube and wavefunction files, and, in general, output from any other code capable of writing the electron density on a three-dimensional grid. It uses a modified version of Bader's and Laidig's approach for achieving origin-independence of local dipoles by referring to internal reference points which can (but do not need to be) bond critical points (BCPs). Furthermore, the code allows the export of critical points and local dipole moments into a POVray readable input format. It is particularly designed for fragments of large systems, for which no BCPs have been calculated for computational efficiency reasons, because large interfragment distances prevent their identification, or because a local partitioning scheme different from AIM was used. The program requires only minimal user input and is written in the Fortran90 programming language. To demonstrate the capabilities of the program, examples are given for covalently and non-covalently bound systems, in particular molecular adsorbates. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lynn Groß
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, Hamburg, 20146, Germany
| | - Carmen Herrmann
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, Hamburg, 20146, Germany
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19
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Groß L, Herrmann C. Local electric dipole moments: A generalized approach. J Comput Chem 2016; 37:2260-5. [PMID: 27520590 DOI: 10.1002/jcc.24440] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 05/26/2016] [Accepted: 06/03/2016] [Indexed: 11/10/2022]
Abstract
We present an approach for calculating local electric dipole moments for fragments of molecular or supramolecular systems. This is important for understanding chemical gating and solvent effects in nanoelectronics, atomic force microscopy, and intensities in infrared spectroscopy. Owing to the nonzero partial charge of most fragments, "naively" defined local dipole moments are origin-dependent. Inspired by previous work based on Bader's atoms-in-molecules (AIM) partitioning, we derive a definition of fragment dipole moments which achieves origin-independence by relying on internal reference points. Instead of bond critical points (BCPs) as in existing approaches, we use as few reference points as possible, which are located between the fragment and the remainder(s) of the system and may be chosen based on chemical intuition. This allows our approach to be used with AIM implementations that circumvent the calculation of critical points for reasons of computational efficiency, for cases where no BCPs are found due to large interfragment distances, and with local partitioning schemes other than AIM which do not provide BCPs. It is applicable to both covalently and noncovalently bound systems. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lynn Groß
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, Hamburg, 20146, Germany
| | - Carmen Herrmann
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, Hamburg, 20146, Germany
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20
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Luka-Guth K, Hambsch S, Bloch A, Ehrenreich P, Briechle BM, Kilibarda F, Sendler T, Sysoiev D, Huhn T, Erbe A, Scheer E. Role of solvents in the electronic transport properties of single-molecule junctions. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:1055-67. [PMID: 27547624 PMCID: PMC4979908 DOI: 10.3762/bjnano.7.99] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/07/2016] [Indexed: 06/06/2023]
Abstract
We report on an experimental study of the charge transport through tunnel gaps formed by adjustable gold electrodes immersed into different solvents that are commonly used in the field of molecular electronics (ethanol, toluene, mesitylene, 1,2,4-trichlorobenzene, isopropanol, toluene/tetrahydrofuran mixtures) for the study of single-molecule contacts of functional molecules. We present measurements of the conductance as a function of gap width, conductance histograms as well as current-voltage characteristics of narrow gaps and discuss them in terms of the Simmons model, which is the standard model for describing transport via tunnel barriers, and the resonant single-level model, often applied to single-molecule junctions. One of our conclusions is that stable junctions may form from solvents as well and that both conductance-distance traces and current-voltage characteristics have to be studied to distinguish between contacts of solvent molecules and of molecules under study.
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Affiliation(s)
| | - Sebastian Hambsch
- Physics Department, University of Konstanz, D-78457 Konstanz, Germany
| | - Andreas Bloch
- Physics Department, University of Konstanz, D-78457 Konstanz, Germany
| | | | | | - Filip Kilibarda
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - Torsten Sendler
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - Dmytro Sysoiev
- Chemistry Department, University of Konstanz, D-78457 Konstanz, Germany
| | - Thomas Huhn
- Chemistry Department, University of Konstanz, D-78457 Konstanz, Germany
| | - Artur Erbe
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany
| | - Elke Scheer
- Physics Department, University of Konstanz, D-78457 Konstanz, Germany
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21
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Capozzi B, Low JZ, Xia J, Liu ZF, Neaton JB, Campos LM, Venkataraman L. Mapping the Transmission Functions of Single-Molecule Junctions. NANO LETTERS 2016; 16:3949-54. [PMID: 27186894 DOI: 10.1021/acs.nanolett.6b01592] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Charge transport phenomena in single-molecule junctions are often dominated by tunneling, with a transmission function dictating the probability that electrons or holes tunnel through the junction. Here, we present a new and simple technique for measuring the transmission functions of molecular junctions in the coherent tunneling limit, over an energy range of 1.5 eV around the Fermi energy. We create molecular junctions in an ionic environment with electrodes having different exposed areas, which results in the formation of electric double layers of dissimilar density on the two electrodes. This allows us to electrostatically shift the molecular resonance relative to the junction Fermi levels in a manner that depends on the sign of the applied bias, enabling us to map out the junction's transmission function and determine the dominant orbital for charge transport in the molecular junction. We demonstrate this technique using two groups of molecules: one group having molecular resonance energies relatively far from EF and one group having molecular resonance energies within the accessible bias window. Our results compare well with previous electrochemical gating data and with transmission functions computed from first principles. Furthermore, with the second group of molecules, we are able to examine the behavior of a molecular junction as a resonance shifts into the bias window. This work provides a new, experimentally simple route for exploring the fundamentals of charge transport at the nanoscale.
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Affiliation(s)
| | | | - Jianlong Xia
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology , Wuhan 430070, China
| | - Zhen-Fei Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Department of Physics, University of California , Berkeley, California 94720, United States
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Department of Physics, University of California , Berkeley, California 94720, United States
- Kavli Energy Nano Sciences Institute at Berkeley , Berkeley, California 94720, United States
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22
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Lin X, Evers F, Groß A. First-principles study of the structure of water layers on flat and stepped Pb electrodes. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:533-43. [PMID: 27335744 PMCID: PMC4901556 DOI: 10.3762/bjnano.7.47] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Accepted: 03/29/2016] [Indexed: 06/06/2023]
Abstract
On the basis of perodic density functional theory (DFT) calculations, we have addressed the geometric structures and electronic properties of water layers on flat and stepped Pb surfaces. In contrast to late d-band metals, on Pb(111) the energy minimum structure does not correspond to an ice-like hexagonal arrangement at a coverage of 2/3, but rather to a distorted structure at a coverage of 1 due to the larger lattice constant of Pb. At stepped Pb surfaces, the water layers are pinned at the step edge and form a complex network consisting of rectangles, pentagons and hexagons. The thermal stability of the water layers has been studied by using ab initio molecular dynamics simulations (AIMD) at a temperature of 140 K. Whereas the water layer on Pb(111) is already unstable at this temperature, the water layers on Pb(100), Pb(311), Pb(511) and Pb(711) exhibit a higher stability because of stronger water-water interactions. The vibrational spectra of the water layers at the stepped surfaces show a characteristic splitting into three modes in the O-H stretch region.
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Affiliation(s)
- Xiaohang Lin
- Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm, Germany
| | - Ferdinand Evers
- Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
| | - Axel Groß
- Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm, Germany
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