1
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Hnid I, Yassin A, Arbouch I, Guérin D, van Dyck C, Sanguinet L, Lenfant S, Cornil J, Blanchard P, Vuillaume D. Molecular Junctions for Terahertz Switches and Detectors. NANO LETTERS 2024; 24:2553-2560. [PMID: 38363554 DOI: 10.1021/acs.nanolett.3c04602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Molecular electronics targets tiny devices exploiting the electronic properties of the molecular orbitals, which can be tailored and controlled by the chemical structure and configuration of the molecules. Many functional devices have been experimentally demonstrated; however, these devices were operated in the low-frequency domain (mainly dc to MHz). This represents a serious limitation for electronic applications, although molecular devices working in the THz regime have been theoretically predicted. Here, we experimentally demonstrate molecular THz switches at room temperature. The devices consist of self-assembled monolayers of molecules bearing two conjugated moieties coupled through a nonconjugated linker. These devices exhibit clear negative differential conductance behaviors (peaks in the current-voltage curves), as confirmed by ab initio simulations, which were reversibly suppressed under illumination with a 30 THz wave. We analyze how the THz switching behavior depends on the THz wave properties (power and frequency), and we benchmark that these molecular devices would outperform actual THz detectors.
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Affiliation(s)
- Imen Hnid
- Institute for Electronics Microelectronics and Nanotechnology (IEMN), CNRS, University of Lille, Av. Poincaré, F-59652 Villeneuve d'Ascq, France
| | - Ali Yassin
- MOLTECH-Anjou, CNRS, University of Angers, SFR MATRIX, F-49000 Angers, France
- Natural Sciences Department, School of Arts and Sciences, Lebanese American University, 1102-2801, Beirut, Lebanon
| | - Imane Arbouch
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000 Mons, Belgium
| | - David Guérin
- Institute for Electronics Microelectronics and Nanotechnology (IEMN), CNRS, University of Lille, Av. Poincaré, F-59652 Villeneuve d'Ascq, France
| | - Colin van Dyck
- Theoretical Chemical Physics group, University of Mons, 7000 Mons, Belgium
| | - Lionel Sanguinet
- MOLTECH-Anjou, CNRS, University of Angers, SFR MATRIX, F-49000 Angers, France
| | - Stéphane Lenfant
- Institute for Electronics Microelectronics and Nanotechnology (IEMN), CNRS, University of Lille, Av. Poincaré, F-59652 Villeneuve d'Ascq, France
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000 Mons, Belgium
| | - Philippe Blanchard
- MOLTECH-Anjou, CNRS, University of Angers, SFR MATRIX, F-49000 Angers, France
| | - Dominique Vuillaume
- Institute for Electronics Microelectronics and Nanotechnology (IEMN), CNRS, University of Lille, Av. Poincaré, F-59652 Villeneuve d'Ascq, France
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2
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Wang J, Zhao Y, Li S, Shen L, Zhang H, Ding C, Wei C, Wang Y, Li Y, Hong W, Li M. Composition and sequence-controlled conductance of crystalline unimolecular monolayers. SCIENCE ADVANCES 2023; 9:eadh0667. [PMID: 37327333 DOI: 10.1126/sciadv.adh0667] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 05/12/2023] [Indexed: 06/18/2023]
Abstract
Understanding how the charge travels through sequence-controlled molecules has been a formidable challenge because of simultaneous requirements in well-controlled synthesis and well-manipulated orientation. Here, we report electrically driven simultaneous synthesis and crystallization as a general strategy to study the conductance of composition and sequence-controlled unioligomer and unipolymer monolayers. The structural disorder of molecules and conductance variations on random positions can be extremely minimized, by uniform synthesis of monolayers unidirectionally sandwiched between electrodes, as an important prerequisite for the reproducible measurement on the micrometer scale. These monolayers show tunable current density and on/off ratios in four orders of magnitude with controlled multistate and massive negative differential resistance (NDR) effects. The conductance of monolayer mainly depends on the metal species in homo-metal monolayers, while the sequence becomes a matter in hetero-metal monolayers. Our work demonstrates a promising way to release an ultra-rich variety of electrical parameters and optimize the functions and performances of multilevel resistive devices.
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Affiliation(s)
- Jinxin Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
| | - Yongjie Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Shumu Li
- Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing Mass Spectrum Center, Beijing 100190, China
| | - Lingyun Shen
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
| | - Hao Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Caijun Ding
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
| | - Chang Wei
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
| | - Yanfang Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Yongfang Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Mao Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei 230026, China
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3
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Wang J, Zhang H, Li S, Ding C, Zhao Y, Long X, Wei C, Wang Y, Li Y, Shen L, Cui S, Hong W, Li M. Crystalline Unipolymer Monolayer with High Modulus and Conductivity. Angew Chem Int Ed Engl 2023; 62:e202216838. [PMID: 36440880 DOI: 10.1002/anie.202216838] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 11/29/2022]
Abstract
The synthesis of crystalline polymer with a well-defined orientated state and a two-dimensional crystalline size beyond a micrometer will be essential to achieve the highest physical feature of polymer material but remain challenging. Herein, we show the synthesis of the crystalline unipolymer monolayer with an unusual ultrahigh modulus that is higher than the ITO substrate and high conductance by simultaneous electrosynthesis and manipulation. We find that the polymer monolayer has fully extended in the vertical and unidirectional orientation, which is proposed to approach their theoretically highest density, modulus, and conductivity among all aggregation formations of the current polymer. The modulus and current density can reach 40 and 1000 times higher than their amorphous counterpart. It is also found that these monolayers exhibit the bias- and length-dependent multiple charge states and asymmetrically negative differential resistance (NDR) effect, indicating that this unique molecular tailoring and ordering design is promising for multilevel resistive memory devices. Our work demonstrates the creation of a crystalline polymer monolayer for approaching the physical limit of polymer electronic materials and also provides an opportunity to challenge the synthetically iterative limit of an isolated ultra-long polymer.
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Affiliation(s)
- Jinxin Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
| | - Hao Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Shumu Li
- Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing Mass Spectrum Center, 100190, Beijing, China
| | - Caijun Ding
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
| | - Yongjie Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Xiuzhen Long
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, 610031, Chengdu, China
| | - Chang Wei
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
| | - Yanfang Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China
| | - Yongfang Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
| | - Lingyun Shen
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
| | - Shuxun Cui
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, 610031, Chengdu, China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China
| | - Mao Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.,University of Science and Technology of China, 230026, Hefei, China
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4
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Park J, Kodaimati MS, Belding L, Root SE, Schatz GC, Whitesides GM. Controlled Hysteresis of Conductance in Molecular Tunneling Junctions. ACS NANO 2022; 16:4206-4216. [PMID: 35230085 DOI: 10.1021/acsnano.1c10155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The problem this paper addresses is the origin of the hysteretic behavior in two-terminal molecular junctions made from an EGaIn electrode and self-assembled monolayers of alkanethiolates terminated in chelates (transition metal dichlorides complexed with 2,2'-bipyridine; BIPY-MCl2). The hysteresis of conductance displayed by these BIPY-MCl2 junctions changes in magnitude depending on the identity of the metal ion (M) and the window of the applied voltage across the junction. The hysteretic behavior of conductance in these junctions appears only in an incoherent (Fowler-Nordheim) tunneling regime. When the complexed metal ion is Mn(II), Fe(II), Co(II), or Ni(II), both incoherent tunneling and hysteresis are observed for a voltage range between +1.0 V and -1.0 V. When the metal ion is Cr(II) or Cu(II), however, only resonant (one-step) tunneling is observed, and the junctions exhibit no hysteresis and do not enter the incoherent tunneling regime. Using this correlation, the conductance characteristics of BIPY-MCl2 junctions can be controlled. This voltage-induced change of conductance demonstrates a simple, fast, and reversible way (i.e., by changing the applied voltage) to modulate conductance in molecular tunneling junctions.
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Affiliation(s)
- Junwoo Park
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Department of Chemistry, Sogang University, Mapo-gu, Seoul 04107, Republic of Korea
| | - Mohamad S Kodaimati
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Lee Belding
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Samuel E Root
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - George C Schatz
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - George M Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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5
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Bhandari S, Yamada A, Hoskins A, Payne J, Aksu H, Dunietz BD. Achieving Predictive Description of Negative Differential Resistance in Molecular Junctions Using a Range‐Separated Hybrid Functional. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Srijana Bhandari
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
| | - Atsushi Yamada
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
| | - Austin Hoskins
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
| | - Jameson Payne
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
| | - Huseyin Aksu
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
- Department of Physics Canakkale Onsekiz Mart University Canakkale 17100 Turkey
| | - Barry D. Dunietz
- Department of Chemistry and Biochemistry Kent State University Kent OH 44242 USA
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6
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Zhao P, Chen G. Spin-polarized and thermospin-polarized transport properties of phthalocyanine dimer based molecular junction with different transition metal atoms. J Chem Phys 2018; 149:134305. [PMID: 30292195 DOI: 10.1063/1.5047081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Based on the first-principles density functional theory combined with the non-equilibrium Green's function method, we have studied the spin-polarized and thermospin-polarized transport properties of phthalocyanine (Pc) dimer based molecular junction with different transition metal (TM = Mn, Fe, Co, Ni) atoms. Our results show that the spin-polarized and thermospin-polarized transport properties can be effectively tuned by changing the central TM atoms, and only the MnPc dimer system exhibits perfect spin/thermal-spin filtering and sizeable giant magnetoresistance (GMR)/thermal-GMR effects. Meantime, the MnPc dimer system reveals a low-bias negative differential resistance effect under the parallel magnetic configuration. These findings suggest that the MnPc dimer system has great potential in developing the high-performance multifunctional spintronic and spin caloritronic devices.
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Affiliation(s)
- P Zhao
- School of Physics and Technology, University of Jinan, Jinan 250022, China
| | - G Chen
- School of Physics and Technology, University of Jinan, Jinan 250022, China
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7
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Zheng H, Zhao Y, Song MX, Wang J, Chen LQ, Sun L, Bai FQ. Influences of donor/acceptor ratio on the optical and electrical properties of the D/A alternating model oligomers: A density functional theory study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 199:260-270. [PMID: 29626817 DOI: 10.1016/j.saa.2018.03.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 03/14/2018] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
We adopted an ingenious method that cut out the DA alternating oligomers from the corresponding DA alternating copolymers. From analyzing the orbital compositions of the HOMOs and LUMOs as well as the reorganization energies, we found the level of charge transfer is increased with the increasing of D/A ratio, but ionization potentials and electron affinities show a contrary trend. Moreover, with the greater ratio, the trend in the nearness of two transitions results in broadening the absorption band in the visible range. That is why experimentally improving the ratio is beneficial for the copolymers used as the p-type materials in the BHJ solar cells. This method is impossible to take the real copolymer system, however, it could provide a strategy to avoid the limitation of the theory level and perform reliable result to study the intrinsic properties of DA alternating copolymers, which can provide a guidance to experimental works.
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Affiliation(s)
- Hao Zheng
- Network and Information Center, Jilin Normal University, Siping 136000, China
| | - Yang Zhao
- Network and Information Center, Jilin Normal University, Siping 136000, China
| | - Ming-Xing Song
- College of Information Technology, Jilin Normal University, Siping 136000, People's Republic of China
| | - Jin Wang
- College of Information Technology, Jilin Normal University, Siping 136000, People's Republic of China.
| | - Li-Qiao Chen
- Innovation & Application Institute, Zhejiang Ocean University, Zhoushan 316022, People's Republic of China.
| | - Lei Sun
- Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Fu-Quan Bai
- Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China.
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8
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Zhang J, Qin Z, Yao K. Pyridine “alligator-clip” as molecular negative differential resistor predicted by first-principles study. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.09.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Min Y, Zhong CG, Dong ZC, Zhao ZY, Zhou PX, Yao KL. A new method to induce molecular low bias negative differential resistance with multi-peaks. J Chem Phys 2016; 144:064308. [PMID: 26874489 DOI: 10.1063/1.4941458] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n- or p-type molecules is proposed. The anthracene-9,10-diono molecule shows strong n-type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule-electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.
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Affiliation(s)
- Y Min
- School of Science, Nantong University, Nantong, Jiangsu 226007, China
| | - C G Zhong
- School of Science, Nantong University, Nantong, Jiangsu 226007, China
| | - Z C Dong
- School of Science, Nantong University, Nantong, Jiangsu 226007, China
| | - Z Y Zhao
- School of Science, Nantong University, Nantong, Jiangsu 226007, China
| | - P X Zhou
- School of Science, Nantong University, Nantong, Jiangsu 226007, China
| | - K L Yao
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
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10
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Li J, Li T, Zhou Y, Wu W, Zhang L, Li H. Distinctive electron transport on pyridine-linked molecular junctions with narrow monolayer graphene nanoribbon electrodes compared with metal electrodes and graphene electrodes. Phys Chem Chem Phys 2016; 18:28217-28226. [DOI: 10.1039/c6cp05007g] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electrodes in the molecular devices are essential for creating functional organic electronic devices.
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Affiliation(s)
- Jie Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
| | - Tao Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
| | - Yi Zhou
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
| | - Weikang Wu
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
| | - Leining Zhang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
| | - Hui Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials
- Ministry of Education
- Shandong University
- Jinan 250061
- People's Republic of China
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11
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Wang L, Li Y, Zhang Y, He H, Zhang J. Dual emission behavior of phenyleneethynylene gold(I) complexes dictated by intersystem crossing: a theoretical perspective. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 137:259-266. [PMID: 25222321 DOI: 10.1016/j.saa.2014.08.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/06/2014] [Accepted: 08/23/2014] [Indexed: 06/03/2023]
Abstract
In commonly studied gold(I) complexes with oligo (o-, p-, or m-phenyleneethynylene) (PE) ligands, an intriguing photophysical behavior is dual emission composed of fluorescence from S1 and phosphorescence from T1 which is dictated by effective intersystem crossing (ISC) process. In order to explore the salient photodynamics of such oligo-PE gold(I) complexes effectively, we have deliberately chosen three model complexes, namely, Ph-C≡C-Au(PMe3) (1a') and Ph-C≡C-(1,m)C6H4-C≡C-Au(PMe3) (m=4, 2a'; m=3, 3a') in place of the real system. Firstly, electronic structure methods based on DFT and TD-DFT are utilized to perform optimization calculations for the ground- and lowest-lying excited states, respectively. Next, basic photophysical properties including absorption and emission spectra are investigated by TD-DFT under the optimized geometries. Besides, on the basis of the electronic spectra herein, we succeed in searching for surface intersections as the minima on the seam of singlet-triplet surface crossings (SCs) at the CASSCF level of theory. By integration of the results available, the process of delayed fluorescence of triplet-triplet annihilation (TTA) and phosphorescence was displayed in detail with SCs playing the lead in monitoring the ISC.
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Affiliation(s)
- Li Wang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Yuanyuan Li
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Yanxin Zhang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Hongqing He
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, PR China
| | - Jinglai Zhang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China.
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12
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Behnia S, Fathizadeh S. Modeling the electrical conduction in DNA nanowires: charge transfer and lattice fluctuation theories. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022719. [PMID: 25768543 DOI: 10.1103/physreve.91.022719] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Indexed: 06/04/2023]
Abstract
An analytical approach is proposed for the investigation of the conductivity properties of DNA. The charge mobility of DNA is studied based on an extended Peyrard-Bishop-Holstein model when the charge carrier is also subjected to an external electrical field. We have obtained the values of some of the system parameters, such as the electron-lattice coupling constant, by using the mean Lyapunov exponent method. On the other hand, the electrical current operator is calculated directly from the lattice operators. Also, we have studied Landauer resistance behavior with respect to the external field, which could serve as the interface between chaos theory tools and electronic concepts. We have examined the effect of two types of electrical fields (dc and ac) and variation of the field frequency on the current flowing through DNA. A study of the current-voltage (I-V) characteristic diagram reveals regions with a (quasi-)Ohmic property and other regions with negative differential resistance (NDR). NDR is a phenomenon that has been observed experimentally in DNA at room temperature. We have tried to study the affected agents in charge transfer phenomena in DNA to better design nanostructures.
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Affiliation(s)
- S Behnia
- Department of Physics, Urmia University of Technology, Orumieh, Iran
| | - S Fathizadeh
- Department of Physics, Urmia University of Technology, Orumieh, Iran
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13
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Stan RC, Kros A, Akkilic N, Appel J, Sanghamitra NJM. Conductance switching and organization of two structurally related molecular wires on gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:953-958. [PMID: 25590414 DOI: 10.1021/la5042713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The self-assembly and electron transfer properties of adsorbed organic molecules are of interest for the construction of miniaturized molecular circuitries. We have investigated with scanning probe microscopy the self-organization of two structurally related molecular wires embedded within a supportive alkanethiol matrix. Our results evidence heterogeneous adsorption patterns of the molecular wires on gold with either incommensurate unit cells driven into assembly by lateral interactions or a dynamic, commensurate distribution on gold, along with formation of distinct 2D phases. We also observed diffusion-based conductance switching for one of the molecular wires, due to its propensity toward weaker lateral interactions and Au-S adatom formation. We have further demonstrated through the use of scanning tunneling spectroscopy differential current-voltage response for each molecular wire, despite their close structural similarity. Such molecular wires embedded in alkanethiol matrix and exhibiting conductance-switching phenomena have the potential to be used for the functionalization of electrodes in bioelectronic devices.
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Affiliation(s)
- Razvan C Stan
- Leiden Institute of Physics-Huygens Laboratories and ‡Leiden Institute of Chemistry-Gorlaeus Laboratories, Leiden University , P.O. Box 9504, 2300 RA Leiden, The Netherlands
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14
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Zhang JL, Zhong JQ, Lin JD, Hu WP, Wu K, Xu GQ, Wee ATS, Chen W. Towards single molecule switches. Chem Soc Rev 2015; 44:2998-3022. [DOI: 10.1039/c4cs00377b] [Citation(s) in RCA: 247] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Scanning tunneling microscope (STM) controlled reversible switching of a single-dipole molecule imbedded in hydrogen-bonded binary molecular networks on graphite.
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Affiliation(s)
- Jia Lin Zhang
- Department of Chemistry
- National University of Singapore
- Singapore
- Department of Physics
- National University of Singapore
| | - Jian Qiang Zhong
- Department of Chemistry
- National University of Singapore
- Singapore
- Department of Physics
- National University of Singapore
| | - Jia Dan Lin
- Department of Chemistry
- National University of Singapore
- Singapore
- Department of Physics
- National University of Singapore
| | - Wen Ping Hu
- School of Science
- Tianjin University
- Tian Jin
- China
| | - Kai Wu
- Singapore-Peking University Research Center for a Sustainable Low-Carbon Future
- Singapore
- College of Chemistry and Molecular Engineering
- Peking University
- Beijing 100871
| | - Guo Qin Xu
- Department of Chemistry
- National University of Singapore
- Singapore
- Singapore-Peking University Research Center for a Sustainable Low-Carbon Future
- Singapore
| | | | - Wei Chen
- Department of Chemistry
- National University of Singapore
- Singapore
- Department of Physics
- National University of Singapore
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15
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Wu H, Sotthewes K, Schön PM, Vancso GJ, Zandvliet HJW. Ordering and dynamics of oligo(phenylene ethynylene) self-assembled monolayers on Au(111). RSC Adv 2015. [DOI: 10.1039/c5ra03577e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Striped-phase of oligo(phenylene ethynylene) molecules on Au(111).
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Affiliation(s)
- Hairong Wu
- Physics of Interfaces and Nanomaterials
- MESA+ Institute for Nanotechnology
- University of Twente
- 7500 AE Enschede
- The Netherlands
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials
- MESA+ Institute for Nanotechnology
- University of Twente
- 7500 AE Enschede
- The Netherlands
| | - Peter M. Schön
- Materials Science and Technology of Polymers
- MESA+ Institute for Nanotechnology
- University of Twente
- 7500 AE Enschede
- The Netherlands
| | - G. Julius Vancso
- Materials Science and Technology of Polymers
- MESA+ Institute for Nanotechnology
- University of Twente
- 7500 AE Enschede
- The Netherlands
| | - Harold J. W. Zandvliet
- Physics of Interfaces and Nanomaterials
- MESA+ Institute for Nanotechnology
- University of Twente
- 7500 AE Enschede
- The Netherlands
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16
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17
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Perrin ML, Frisenda R, Koole M, Seldenthuis JS, Gil JAC, Valkenier H, Hummelen JC, Renaud N, Grozema FC, Thijssen JM, Dulić D, van der Zant HSJ. Large negative differential conductance in single-molecule break junctions. NATURE NANOTECHNOLOGY 2014; 9:830-4. [PMID: 25173832 DOI: 10.1038/nnano.2014.177] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 07/21/2014] [Indexed: 05/24/2023]
Abstract
Molecular electronics aims at exploiting the internal structure and electronic orbitals of molecules to construct functional building blocks. To date, however, the overwhelming majority of experimentally realized single-molecule junctions can be described as single quantum dots, where transport is mainly determined by the alignment of the molecular orbital levels with respect to the Fermi energies of the electrodes and the electronic coupling with those electrodes. Particularly appealing exceptions include molecules in which two moieties are twisted with respect to each other and molecules in which quantum interference effects are possible. Here, we report the experimental observation of pronounced negative differential conductance in the current-voltage characteristics of a single molecule in break junctions. The molecule of interest consists of two conjugated arms, connected by a non-conjugated segment, resulting in two coupled sites. A voltage applied across the molecule pulls the energy of the sites apart, suppressing resonant transport through the molecule and causing the current to decrease. A generic theoretical model based on a two-site molecular orbital structure captures the experimental findings well, as confirmed by density functional theory with non-equilibrium Green's functions calculations that include the effect of the bias. Our results point towards a conductance mechanism mediated by the intrinsic molecular orbitals alignment of the molecule.
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Affiliation(s)
- Mickael L Perrin
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Riccardo Frisenda
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Max Koole
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Johannes S Seldenthuis
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Jose A Celis Gil
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Hennie Valkenier
- 1] Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands [2] School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK
| | - Jan C Hummelen
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Nicolas Renaud
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Ferdinand C Grozema
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Joseph M Thijssen
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Diana Dulić
- 1] Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands [2] Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago de Chile, Chile
| | - Herre S J van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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18
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Huang MJ, Hua SA, Fu MD, Huang GC, Yin C, Ko CH, Kuo CK, Hsu CH, Lee GH, Ho KY, Wang CH, Yang YW, Chen IC, Peng SM, Chen CH. The first heteropentanuclear extended metal-atom chain: [Ni⁺-Ru₂⁵⁺-Ni²⁺-Ni²⁺ (tripyridyldiamido)₄(NCS)₂]. Chemistry 2014; 20:4526-31. [PMID: 24677325 DOI: 10.1002/chem.201400067] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 11/07/2022]
Abstract
This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru2(5+) unit. This [Ru2]-containing EMAC exhibits single-molecule conductance four-fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium-modulated EMAC.
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Affiliation(s)
- Min-Jie Huang
- Department of Chemistry and Center for Emerging Material and Advanced Devices, National Taiwan University, Taipei 10617 (Taiwan), Fax: (+886) 2-33666359
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19
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Lan TN. Electronic transport properties of molecular junctions based on the direct binding of aromatic ring to electrodes. Chem Phys 2014. [DOI: 10.1016/j.chemphys.2013.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Kuo CT, Su LC, Chen CH. Transitions between Electron Transporting Mechanisms in Molecular Junctions and Transistors. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201300504] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Majima Y, Ogawa D, Iwamoto M, Azuma Y, Tsurumaki E, Osuka A. Negative differential resistance by molecular resonant tunneling between neutral tribenzosubporphine anchored to a Au(111) surface and tribenzosubporphine cation adsorbed on to a tungsten tip. J Am Chem Soc 2013; 135:14159-66. [PMID: 24024563 DOI: 10.1021/ja404512w] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Tribenzosubporphyrins are boron(III)-chelated triangular bowl-shaped ring-contracted porphyrins that possess a 14π-aromatic circuit. Their flat molecular shapes and discrete molecular orbital diagrams make them ideal for observation by scanning tunneling microscopy (STM). Expanding their applications toward single molecule-based devices requires a fundamental knowledge of single molecular conductance between tribenzosubporphines and the STM metal tip. We utilized a tungsten (W) STM tip to investigate the electronic properties of B-(5-mercaptopentoxy)tribenzosubporphine 1 at the single molecular level. B-(5-mercaptopentoxy)-tribenzosubporphine 1 was anchored to the Au(111) surface via reaction with 1-heptanethiol linkers that were preorganized as a self-assembled monolayer (C7S SAM) on the Au(111) substrate. This arrangement ensured that 1 was electronically decoupled from the metal surface. Differential conductance (dI/dV - V) measurements with the bare W tip exhibited a broad gap region of low conductance and three distinct responses at 2.4,-1.3, and -2.1 V. Bias-voltage-dependent STM imaging of 1 at 65 K displayed a triangle shape at -2.1 < V < -1.3 V and a circle shape at V < -2.1 V, reflecting its HOMO and HOMO-1, respectively. In addition, different conductance behaviors were reproducibly observed, which has been ascribed to the adsorption of a tribenzosubporphine-cation on the W tip. When using a W tip doped with preadsorbed tribenzosubporphine-cation, negative differential resistance (NDR) phenomena were clearly observed in a reproducible manner with a peak-to-valley ratio of 2.6, a value confirmed by spatial mapping conductance measurements. Collectively, the observed NDR phenomena have been attributed to effective molecular resonant tunneling between a neutral tribenzosubporphine anchored to the metal surface and a tribenzosubporphine cation adsorbed on a W tip.
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Affiliation(s)
- Yutaka Majima
- Materials and Structures Laboratory, Tokyo Institute of Technology , Yokohama 226-8503, Japan
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22
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Zhou J, Samanta S, Guo C, Locklin J, Xu B. Measurements of contact specific low-bias negative differential resistance of single metalorganic molecular junctions. NANOSCALE 2013; 5:5715-5719. [PMID: 23712631 DOI: 10.1039/c3nr01284k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Negative differential resistance (NDR) behaviors of single molecule junctions composed of a thiol-terminated Ru(ii) bis-terpyridine (Ru(tpy-SH)2) molecule sandwiched between two gold electrodes are measured using a specifically modified scanning probe microscope break junction technique (SPMBJ) at room temperature. The low-bias (0.623 ± 0.135 V) NDR observed for one of the three conductance groups is contact specific and is caused by a bias induced electrode-molecule coupling changes.
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Affiliation(s)
- Jianfeng Zhou
- Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30602, USA
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23
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Affiliation(s)
- Bala Krishna Pathem
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Shelley A. Claridge
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Yue Bing Zheng
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Paul S. Weiss
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
- Department of Materials Science and Engineering, University of California, Los Angeles, California 90095;
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24
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Wan H, Xu Y, Zhou G. Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups. J Chem Phys 2012; 136:184704. [PMID: 22583306 DOI: 10.1063/1.4712615] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the electronic transport properties for a molecular device model constructed by a phenylene ethynylene oligomer molecular with different side groups embedding in a carbon chain between two graphene electrodes. Using the first-principles method, the unusual dual conductance, negative differential resistance (NDR) behavior with large peak to valley ratio, and obvious rectifying performance are numerically observed in such proposed molecular device. The analysis of the molecular projected self-consistent Hamiltonian and the evolution of the frontier molecular orbitals (MOs) as well as transmission coefficients under various external voltage biases gives an inside view of the observed results, which suggests that the dual conductance behavior and rectifying performance are due to the asymmetry distribution of the frontier MOs as well as the corresponding coupling between the molecule and electrodes. But the NDR behavior comes from the conduction orbital being suppressed at certain bias. Interestingly, the conduction properties can be tuned by introducing side groups to the molecule and the rectification as well as the NDR behavior (peak to valley ratio) can be improved by adding different side groups in the device model.
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Affiliation(s)
- Haiqing Wan
- Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Hunan Normal University, Changsha 410081, China
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25
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Yu C, Liu H, Ni W, Gao N, Zhao J, Zhang H. Theoretical study of the source-drain current and gate leakage current to understand the graphene field-effect transistors. Phys Chem Chem Phys 2011; 13:3461-7. [DOI: 10.1039/c0cp01026j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Crivillers N, Paradinas M, Mas-Torrent M, Bromley ST, Rovira C, Ocal C, Veciana J. Negative differential resistance (NDR) in similar molecules with distinct redox behaviour. Chem Commun (Camb) 2011; 47:4664-6. [DOI: 10.1039/c1cc10677e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Silvestri F, Marrocchi A, Seri M, Kim C, Marks TJ, Facchetti A, Taticchi A. Solution-Processable Low-Molecular Weight Extended Arylacetylenes: Versatile p-Type Semiconductors for Field-Effect Transistors and Bulk Heterojunction Solar Cells. J Am Chem Soc 2010; 132:6108-23. [DOI: 10.1021/ja910420t] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fabio Silvestri
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Assunta Marrocchi
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Mirko Seri
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Choongik Kim
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Tobin J. Marks
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Antonio Facchetti
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - Aldo Taticchi
- Department of Chemistry, the Argonne-Northwestern Solar Energy Research Center, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, and Department of Chemistry, University of Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
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28
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Deng X, Zhang Z, Zhou J, Qiu M, Tang G. Length and end group dependence of the electronic transport properties in carbon atomic molecular wires. J Chem Phys 2010; 132:124107. [DOI: 10.1063/1.3363894] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Parida P, Lakshmi S, Pati SK. Negative differential resistance in nanoscale transport in the Coulomb blockade regime. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:095301. [PMID: 21817384 DOI: 10.1088/0953-8984/21/9/095301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Motivated by recent experiments, we have studied the transport behavior of coupled quantum dot systems in the Coulomb blockade regime using the master (rate) equation approach. We explore how electron-electron interactions in a donor-acceptor system, resembling weakly coupled quantum dots with varying charging energy, can modify the system's response to an external bias, taking it from normal Coulomb blockade behavior to negative differential resistance (NDR) in the current-voltage characteristics.
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Affiliation(s)
- Prakash Parida
- Theoretical Sciences Unit, Jawaharlal Nehru Centre For Advanced Scientific Research, Jakkur Campus, Bangalore 560064, India. DST Unit on Nanoscience, Jakkur Campus, Bangalore 560064, India
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30
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Pati R, McClain M, Bandyopadhyay A. Origin of negative differential resistance in a strongly coupled single molecule-metal junction device. PHYSICAL REVIEW LETTERS 2008; 100:246801. [PMID: 18643607 DOI: 10.1103/physrevlett.100.246801] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Indexed: 05/19/2023]
Abstract
A new mechanism is proposed to explain the origin of negative differential resistance (NDR) in a strongly coupled single molecule-metal junction. A first-principles quantum transport calculation in a Fe-terpyridine linker molecule sandwiched between a pair of gold electrodes is presented. Upon increasing the applied bias, it is found that a new phase in the broken symmetry wave function of the molecule emerges from the mixing of occupied and unoccupied molecular orbitals. As a consequence, a nonlinear change in the coupling between the molecule and the lead is evolved resulting in NDR. This model can be used to explain NDR in other classes of metal-molecule junction devices.
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Affiliation(s)
- Ranjit Pati
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA.
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31
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Conformational study of a strained tolanophane by dynamic 1H NMR spectroscopy and computational methods. MONATSHEFTE FUR CHEMIE 2008. [DOI: 10.1007/s00706-008-0912-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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32
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Darabi HR, Jadidi K, Mohebbi AR, Faraji L, Aghapoor K, Shahbazian S, Azimzadeh M, Nasseri SM. A Simple and Convenient Strategy for the Synthesis of Tolanophanes: Synthesis, Characterization and Conformational Analysis of a Novel Tolanophane. Supramol Chem 2008. [DOI: 10.1080/10610270701258642] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Hossein Reza Darabi
- a Chemistry & Chemical Engineering Research Center of Iran (CCERCI) , P.O. Box 14335-186, Tehran, Iran
| | - Khosrow Jadidi
- b Chemistry Department , Faculty of Science, Shahid Beheshti University , P.O. Box 19395-4716, Tehran, Iran
| | - Ali Reza Mohebbi
- a Chemistry & Chemical Engineering Research Center of Iran (CCERCI) , P.O. Box 14335-186, Tehran, Iran
| | - Laleh Faraji
- b Chemistry Department , Faculty of Science, Shahid Beheshti University , P.O. Box 19395-4716, Tehran, Iran
| | - Kioumars Aghapoor
- a Chemistry & Chemical Engineering Research Center of Iran (CCERCI) , P.O. Box 14335-186, Tehran, Iran
| | - Shant Shahbazian
- b Chemistry Department , Faculty of Science, Shahid Beheshti University , P.O. Box 19395-4716, Tehran, Iran
| | - Marjan Azimzadeh
- a Chemistry & Chemical Engineering Research Center of Iran (CCERCI) , P.O. Box 14335-186, Tehran, Iran
| | - Sareh M. Nasseri
- a Chemistry & Chemical Engineering Research Center of Iran (CCERCI) , P.O. Box 14335-186, Tehran, Iran
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33
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Moore AM, Mantooth BA, Dameron AA, Donhauser ZJ, Lewis PA, Smith RK, Fuchs DJ, Weiss PS. Measurements and Mechanisms of Single-Molecule Conductance Switching. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/978-3-540-77968-1_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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34
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Electric Field Effect on the Adsorption State of Methylthiolate on Au(111). E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2008. [DOI: 10.1380/ejssnt.2008.99] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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35
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Pejov L, Rosa ML, Kocarev L. Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.05.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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36
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Yeganeh S, Galperin M, Ratner MA. Switching in Molecular Transport Junctions: Polarization Response. J Am Chem Soc 2007; 129:13313-20. [DOI: 10.1021/ja0730967] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sina Yeganeh
- Contribution from the Department of Chemistry, Center for Nanofabrication and Molecular Self Assembly, and Materials Research Science and Engineering Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Michael Galperin
- Contribution from the Department of Chemistry, Center for Nanofabrication and Molecular Self Assembly, and Materials Research Science and Engineering Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Mark A. Ratner
- Contribution from the Department of Chemistry, Center for Nanofabrication and Molecular Self Assembly, and Materials Research Science and Engineering Center, Northwestern University, Evanston, Illinois 60208-3113
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37
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Terashima T, Nakashima T, Kawai T. Engineering Control over the Conformation of the Alkyne−Aryl Bond by the Introduction of Cationic Charge. Org Lett 2007; 9:4195-8. [PMID: 17877361 DOI: 10.1021/ol7016966] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel arylene-ethynylene molecule has been synthesized. This molecule is more stable in a coplanar form than in a twisted form as in the cases of typical arylene-ethynylene molecules. When the cationic charge was introduced into the pi-conjugated system, the perpendicularly twisted form became more stable than the coplanar state. The conformational change was controlled by introduction and removal of cationic charge, confirmed by the absorption and fluorescence spectroscopy and DFT calculation.
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Affiliation(s)
- Takashi Terashima
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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38
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Beeby A, Findlay KS, Goeta AE, Porrès L, Rutter SR, Thompson AL. Engineering a twist in 9,10-diethynylanthracenes by steric interactions. Photochem Photobiol Sci 2007; 6:982-6. [PMID: 17721597 DOI: 10.1039/b707750e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of 9,10-bis(phenylethynyl)anthracenes decorated with sterically demanding tert-butyl substituents have been prepared and spectroscopically characterised. We demonstrate that the introduction of two bulky substituents in the ortho position of the phenyl rings effectively locks the ground state into a conformation in which the three rings are orthogonal. Fluorescence spectroscopy reveals evidence for partial planarisation of this compound in the excited state at ambient temperature, but this is prevented in low temperature solvent glasses.
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Affiliation(s)
- Andrew Beeby
- Department of Chemistry, University of Durham, Durham, UK.
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39
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Albinsson B, Eng MP, Pettersson K, Winters MU. Electron and energy transfer in donor-acceptor systems with conjugated molecular bridges. Phys Chem Chem Phys 2007; 9:5847-64. [PMID: 17989792 DOI: 10.1039/b706122f] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron and energy transfer reactions in covalently connected donor-bridge-acceptor assemblies are strongly dependent, not only on the donor-acceptor distance, but also on the electronic structure of the bridge. In this article we describe some well characterised systems where the bridges are pi-conjugated chromophores, and where, specifically, the interplay between bridge length and energy plays an important role for the donor-acceptor electronic coupling. For any application that relies on the transport of electrons, for example molecule based solar cells or molecular scale electronics, it will be imperative to predict the electron transfer capabilities of different molecular structures. The potential difficulties with making such predictions and the lack of suitable models are also discussed.
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Affiliation(s)
- Bo Albinsson
- Department of Chemical and Biological Engineering/Physical Chemistry, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
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40
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Axford D, Davis JJ, Wang N, Wang D, Zhang T, Zhao J, Peters B. Molecularly Resolved Protein Electromechanical Properties. J Phys Chem B 2007; 111:9062-8. [PMID: 17628094 DOI: 10.1021/jp070262o] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previous work has shown that protein molecules can be trapped between the conductive surfaces presented by a metal-coated AFM probe and an underlying planar substrate where their molecule-specific conductance characteristics can be assayed. Herein, we demonstrate that transport across such a derived metal-protein-electrode junction falls within three, pressure-dependent, regimes and, further, that pressure-dependent conductance can be utilized in analyzing temporal variations of protein fold. Specifically, the electronic and mechanical properties of the metalloprotein azurin have been characterized under conditions of anisotropic vertical compression through the use of a conducting atomic force microscope (CP-AFM). By utilizing the ability of azurin to chemically self-assemble on the gold surface presented either by the apex of a suitably coated AFM probe or a planar metallic surface, molecular-level transport characteristics are assayable. Under conditions of low force, typically less than 2 nN, the weak physical and electronic coupling between the protein and the conducting contacts impedes tunneling and leads to charge buildup followed by dielectric breakdown. At slightly increased force, 3-5 nN, the copper protein exhibits temporal electron occupation with observable negative differential resistance, while the redox-inactive zinc mutant does not. At imposed loads greater than 5 nN, appreciable electron tunneling can be detected even at low bias for both the redox-active and -inactive species. Dynamic current-voltage characteristics have been recorded and are well-described by a modified Simmons tunneling model. Subsequent analyses enable the electron tunneling barrier height and barrier length to be determined under conditions of quantified vertical stress. The variance observed describes, in essence, the protein's mechanical properties within the confines of the tunnel junction.
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Affiliation(s)
- Daniel Axford
- Chemical Research Laboratory, Mansfield Road, University of Oxford, Oxford OX1 3TA, United Kingdom
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41
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Amadei A, D’Abramo M, Nola AD, Arcadi A, Cerichelli G, Aschi M. Theoretical study of intramolecular charge transfer in π-conjugated oligomers. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.12.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Kula M, Jiang J, Lu W, Luo Y. Effects of hydrogen bonding on current-voltage characteristics of molecular junctions. J Chem Phys 2006; 125:194703. [PMID: 17129146 DOI: 10.1063/1.2364494] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a first-principles study of hydrogen bonding effect on current-voltage characteristics of molecular junctions. Three model charge-transfer molecules, 2'-amino-4,4'-di(ethynylphenyl)-1-benzenethiolate (DEPBT-D), 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate (DEPBT-A), and 2'-amino-4,4'-di(ethynylphenyl)-5'-nitro-1-benzenethiolate (DEPBT-DA), have been examined and compared with the corresponding hydrogen bonded complexes formed with different water molecules. Large differences in current-voltage characteristics are observed for DEPBT-D and DEPBT-A molecules with or without hydrogen bonded waters, while relatively small differences are found for DEPBT-DA. It is predicted that the presence of water clusters can drastically reduce the conductivities of the charge-transfer molecules. The underlying microscopic mechanism has been discussed.
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Affiliation(s)
- Mathias Kula
- Theoretical Chemistry, Royal Institute of Technology, AlbaNova, S-106 91 Stockholm, Sweden
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43
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Choi YC, Kim WY, Park KS, Tarakeshwar P, Kim KS, Kim TS, Lee JY. Role of molecular orbitals of the benzene in electronic nanodevices. J Chem Phys 2006; 122:094706. [PMID: 15836161 DOI: 10.1063/1.1858851] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In an effort to examine the intricacies of electronic nanodevices, we present an atomistic description of the electronic transport properties of an isolated benzene molecule. We have carried out ab initio calculations to understand the modulation of the molecular orbitals (MOs) and their energy spectra under the external electric field, and conducting behavior of the benzene molecule. Our study shows that with an increase in the applied electric field, the energy of the third lowest unoccupied molecular orbital (LUMO) of benzene decreases, while the first and second LUMO energies are not affected. Above a certain threshold of the external electric field, the third LUMO is lowered below the original LUMO and becomes the real LUMO. Since the transport through a molecule is to a large extent mediated by the molecular orbitals, the change in MOs can lead to a dramatic increase in the current passing through the benzene molecule. Thus, in the course of this study, we show that the modulation of the molecular orbitals in the presence of a tuning parameter(s) such as the external electric field can play important roles in the operation of molecular devices. We believe that this understanding would be helpful in the design of electronic nanodevices.
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Affiliation(s)
- Young Cheol Choi
- Division of Molecular and Life Sciences, Department of Chemistry, National Creative Research Initiative Center for Superfunctional Materials, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea
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44
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Keane ZK, Ciszek JW, Tour JM, Natelson D. Three-terminal devices to examine single-molecule conductance switching. NANO LETTERS 2006; 6:1518-21. [PMID: 16834442 DOI: 10.1021/nl061117+] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative switching mechanisms.
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Affiliation(s)
- Z K Keane
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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45
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Dalgleish H, Kirczenow G. A new approach to the realization and control of negative differential resistance in single-molecule nanoelectronic devices: designer transition metal-thiol interface States. NANO LETTERS 2006; 6:1274-8. [PMID: 16771593 DOI: 10.1021/nl060040m] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
On the basis of ab initio and semiempirical calculations, we predict single alkane dithiolate molecules bridging transition metal nanoelectrodes (including Pd/Rh, Pt/Rh, and Pt/Pt) to exhibit negative differential resistance (NDR). The mechanism is resonant conduction via interface states arising from hybridization between molecular thiol groups and transition metal d orbitals. We show how the NDR realized in this new way can be controlled by tailoring interface state properties through appropriate choice of nanoelectrode transition metals and surface structures.
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Affiliation(s)
- Hugh Dalgleish
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
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46
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Wang C, Pålsson LO, Batsanov AS, Bryce MR. Molecular wires comprising pi-extended ethynyl- and butadiynyl-2,5-diphenyl-1,3,4-oxadiazole derivatives: synthesis, redox, structural, and optoelectronic properties. J Am Chem Soc 2006; 128:3789-99. [PMID: 16536554 DOI: 10.1021/ja0577600] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2,5-Diphenyl-1,3,4-oxadiazole (OXD) derivatives with terminal ethynyl- (4a,b) and butadiynyl- (8a,b) substituents have been synthesized in high yields. 2-Methyl-3,5-hexadiyn-2-ol has not been exploited previously in the synthesis of terminal butadiynes. Crystals of 8a and 8b are remarkably stable to long-term storage under ambient conditions. The X-ray crystal structure of 8a reveals that the butadiyne moieties are spatially isolated by the aromatic moieties, which explains the high stability. Two series of derived pi-conjugated molecules, Donor-(C[triple bond]C)(n)-OXD (n = 1, 2) and OXD-(C[triple bond]C)(n)-Donor-(C[triple bond]C)(n)-OXD (n = 1) [Donor = tetrathiafulvalene (TTF), bithiophene, 9-(4,5-dimethyl-1,3-dithiol-2-ylidene)fluorene, and triphenylamine], have been synthesized using Sonogashira reactions and characterized by X-ray crystallography, cyclic voltammetry, and optical absorption/emission spectroscopy. The electron-withdrawing effect of the OXD units is manifested by a positive shift of the donor oxidation waves in these systems: the butadiynylene spacer (n = 2) further shifts the first oxidation waves by 40-80 mV compared to analogues n = 1. The absorption spectra of TTF-OXD hybrids 10d and 11 are blue-shifted by 80 nm compared to the bithienyl-bridged derivative 10f and are similar to the butadiynyl-OXD building-block 8a, demonstrating that conjugation is disrupted by a neutral TTF unit. Solutions of the TTF-OXD and 9-(4,5-dimethyl-1,3-dithiol-2-ylidene)fluorene-OXD hybrids, 10d, 10g, 11, and 13, are only very weakly fluorescent due to quenching from the electron-donor moieties. In contrast, the triphenylamine-OXD hybrids 12a, 12b, 14a, and 14b are fluorescent; the PLQYs of the butadiynylene derivatives 14a and 14b are lower than those of the ethynylene-bridged analogues 12a and 12b.
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Affiliation(s)
- Changsheng Wang
- Department of Chemistry, University of Durham, Durham DH1 3LE, UK
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47
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Sitha S, K B. Role of aromatic π-bridge on electron transport property in a donor–bridge–acceptor system: A computational study on frontier molecular orbitals. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.theochem.2005.12.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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48
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Moore AM, Dameron AA, Mantooth BA, Smith RK, Fuchs DJ, Ciszek JW, Maya F, Yao Y, Tour JM, Weiss PS. Molecular Engineering and Measurements To Test Hypothesized Mechanisms in Single Molecule Conductance Switching. J Am Chem Soc 2006; 128:1959-67. [PMID: 16464097 DOI: 10.1021/ja055761m] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Six customized phenylene-ethynylene-based oligomers have been studied for their electronic properties using scanning tunneling microscopy to test hypothesized mechanisms of stochastic conductance switching. Previously suggested mechanisms include functional group reduction, functional group rotation, backbone ring rotation, neighboring molecule interactions, bond fluctuations, and hybridization changes. Here, we test these hypotheses experimentally by varying the molecular designs of the switches; the ability of the molecules to switch via each hypothetical mechanism is selectively engineered into or out of each molecule. We conclude that hybridization changes at the molecule-surface interface are responsible for the switching we observe.
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Affiliation(s)
- Amanda M Moore
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA
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49
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Polyansky DE, Danilov EO, Voskresensky SV, Rodgers MAJ, Neckers DC. Delocalization of Free Electron Density through Phenylene−Ethynylene: Structural Changes Studied by Time-Resolved Infrared Spectroscopy. J Am Chem Soc 2005; 127:13452-3. [PMID: 16190681 DOI: 10.1021/ja053120l] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have studied the photochemistry of 1,4-bis(2-[4-tert-butylperoxycarbonylphenyl]ethynyl)benzene (1) and tert-butyl 4-(2-{4-[2-(4-phenyloxycarbonylphenyl)-1-ethynyl]phenyl}-1-ethynyl)peroxybenzoate (2). Excitation of 1 and 2 by a 355-nm laser pulse leads to the rapid formation of aroyloxyl radicals. An unpaired electron conjugated with the phenylene-ethynylene core is substantially delocalized over the pi-system of the chromophore. The -CC- vibrational frequencies of these radicals are red-shifted relative to 1 and 2 as measured by time-resolved IR spectroscopy. This shift is attributed to the change in the triple bond character due to delocalization of the free electron.
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Affiliation(s)
- Dmitry E Polyansky
- Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA
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50
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Oseki Y, Fujitsuka M, Hara M, Cai X, Ie Y, Aso Y, Majima T. Photophysical Properties of Oligo(2,3-Thienyleneethynylene)s. J Phys Chem B 2005; 109:10695-8. [PMID: 16852298 DOI: 10.1021/jp050270+] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photophysical properties of oligo(2,3-thienyleneethynylene)s (nTE, n denotes the number of thiophene rings, n = 2, 3) in benzene were investigated using steady-state, time-resolved fluorescence, and transient absorption spectroscopies. For 2TE, generation of the radiative S2 and nonradiative S1 states was confirmed. Upon excitation, the S2 state was initially generated and deactivated to the S1 state within 10 ps. The S1 state exhibited the transient absorption band at 470 nm, of which the lifetime was estimated to be 5.3 ns. In the case of 3TE, on the other hand, it was revealed that the radiative S1 state with a transient absorption peak at 650 nm was generated upon excitation. The T1 states of nTE were generated from the S1 states. The quantum yields were estimated to be 0.52 and 0.54 for 2TE and 3TE, respectively. Extremely fast reactions in the higher triplet excited state were indicated for both 2TE and 3TE.
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Affiliation(s)
- Yosuke Oseki
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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