1
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Chen Y, Bâldea I, Yu Y, Liang Z, Li MD, Koren E, Xie Z. CP-AFM Molecular Tunnel Junctions with Alkyl Backbones Anchored Using Alkynyl and Thiol Groups: Microscopically Different Despite Phenomenological Similarity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:4410-4423. [PMID: 38348971 PMCID: PMC10906003 DOI: 10.1021/acs.langmuir.3c03759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/24/2024] [Accepted: 01/24/2024] [Indexed: 02/28/2024]
Abstract
In this paper, we report results on the electronic structure and transport properties of molecular junctions fabricated via conducting probe atomic force microscopy (CP-AFM) using self-assembled monolayers (SAMs) of n-alkyl chains anchored with acetylene groups (CnA; n = 8, 9, 10, and 12) on Ag, Au, and Pt electrodes. We found that the current-voltage (I-V) characteristics of CnA CP-AFM junctions can be very accurately reproduced by the same off-resonant single-level model (orSLM) successfully utilized previously for many other junctions. We demonstrate that important insight into the energy-level alignment can be gained from experimental data of transport (processed via the orSLM) and ultraviolet photoelectron spectroscopy combined with ab initio quantum chemical information based on the many-body outer valence Green's function method. Measured conductance GAg < GAu < GPt is found to follow the same ordering as the metal work function ΦAu < ΦAu < ΦPt, a fact that points toward a transport mediated by an occupied molecular orbital (MO). Still, careful data analysis surprisingly revealed that transport is not dominated by the ubiquitous HOMO but rather by the HOMO-1. This is an important difference from other molecular tunnel junctions with p-type HOMO-mediated conduction investigated in the past, including the alkyl thiols (CnT) to which we refer in view of some similarities. Furthermore, unlike in CnT and other junctions anchored with thiol groups investigated in the past, the AFM tip causes in CnA an additional MO shift, whose independence of size (n) rules out significant image charge effects. Along with the prevalence of the HOMO-1 over the HOMO, the impact of the "second" (tip) electrode on the energy level alignment is another important finding that makes the CnA and CnT junctions different. What ultimately makes CnA unique at the microscopic level is a salient difference never reported previously, namely, that CnA's alkyne functional group gives rise to two energetically close (HOMO and HOMO-1) orbitals. This distinguishes the present CnA from the CnT, whose HOMO stemming from its thiol group is well separated energetically from the other MOs.
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Affiliation(s)
- Yuhong Chen
- Department
of Materials Science and Engineering, Technion-Israel
Institute of Technology, Haifa 3200003, Israel
- Department
of Materials Science and Engineering, Guangdong Provincial Key Laboratory
of Materials and Technologies for Energy Conversion (MATEC), Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, China
| | - Ioan Bâldea
- Theoretical
Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Yongxin Yu
- Department
of Materials Science and Engineering, Guangdong Provincial Key Laboratory
of Materials and Technologies for Energy Conversion (MATEC), Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, China
| | - Zining Liang
- Department
of Materials Science and Engineering, Guangdong Provincial Key Laboratory
of Materials and Technologies for Energy Conversion (MATEC), Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, China
| | - Ming-De Li
- Department
of Chemistry and Key Laboratory for Preparation and Application of
Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, China
| | - Elad Koren
- Department
of Materials Science and Engineering, Technion-Israel
Institute of Technology, Haifa 3200003, Israel
| | - Zuoti Xie
- Department
of Materials Science and Engineering, Technion-Israel
Institute of Technology, Haifa 3200003, Israel
- Department
of Materials Science and Engineering, Guangdong Provincial Key Laboratory
of Materials and Technologies for Energy Conversion (MATEC), Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, China
- Quantum
Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen-Hong Kong International Science and Technology
Park, No. 3 Binglang
Road, Futian District, Shenzhen, Guangdong 518048, China
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2
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Kong GD, Jang J, Choi S, Lim G, Kim IS, Ohto T, Maeda S, Tada H, Yoon HJ. Dynamic Variation of Rectification Observed in Supramolecular Mixed Mercaptoalkanoic Acid. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2305997. [PMID: 37726226 DOI: 10.1002/smll.202305997] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/29/2023] [Indexed: 09/21/2023]
Abstract
Functionality in molecular electronics relies on inclusion of molecular orbital energy level within a transmission window. This can be achieved by designing the active molecule with accessible energy levels or by widening the window. While many studies have adopted the first approach, the latter is challenging because defects in the active molecular component cause low breakdown voltages. Here, it is shown that control over the packing structure of monolayer via supramolecular mixing transforms an inert molecule into a highly tunable rectifier. Binary mixed monolayer composed of alkanethiolates with and without carboxylic acid head group as a proof of concept is formed via a surface-exchange reaction. The monolayer withstands high voltages up to |4.5 V| and shows a dynamic rectification-external bias relationship in magnitude and polarity. Sub-highest occupied molecular orbital (HOMO) levels activated by the widened transmission window account for these observations. This work demonstrates that simple supramolecular mixing can imbue new electrical properties in electro-inactive organic molecules.
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Affiliation(s)
- Gyu Don Kong
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Jiung Jang
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Suin Choi
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Gayoung Lim
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - In Soo Kim
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- KIST-SKKU Carbon-Neutral Research Center, Sungkyunkwan University (SKKU), Suwon, 16419, South Korea
| | - Tatsuhiko Ohto
- Department of Materials Design Innovation Engineering, Nagoya University, Furo-cho, Chikusa-ku, Aichi, 464-8603, Japan
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Seiya Maeda
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Hirokazu Tada
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
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Xie Y, Wang CY, Chen N, Cao Z, Wu G, Yin B, Li Y. Supramolecular Memristor Based on Bistable [2]Catenanes: Toward High-Density and Non-Volatile Memory Devices. Angew Chem Int Ed Engl 2023; 62:e202309605. [PMID: 37651501 DOI: 10.1002/anie.202309605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/01/2023]
Abstract
The ever-increasing demand for data storage and neuromorphic computing calls for innovative, high-density solutions, such as resistive random-access memory (RRAM). However, the integration of resistive switching and rectification at the nanoscale remains a formidable challenge. In this study, we introduce a bistable [2]catenane-based supramolecular junction that simultaneously functions as a resistive switch and a diode. All supramolecular junctions are highly stable and reproducible over thousands of resistive switching cycles, because the nano-confinement of two mechanically interlocked rings can stabilize the radical states of pyridinium moieties under ambient conditions. The successful realization of supramolecular junctions in functionality with a thickness of approximately 2 nm presents a promising avenue for the development of molecule-scale based RRAM for a better solution to high density and energy efficiency.
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Affiliation(s)
- Yu Xie
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Cai-Yun Wang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Ningyue Chen
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhou Cao
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Guangcheng Wu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Bangchen Yin
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yuan Li
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
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4
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Peng W, Chen N, Wang C, Xie Y, Qiu S, Li S, Zhang L, Li Y. Fine-Tuning the Molecular Design for High-Performance Molecular Diodes Based on Pyridyl Isomers. Angew Chem Int Ed Engl 2023; 62:e202307733. [PMID: 37401826 DOI: 10.1002/anie.202307733] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/28/2023] [Accepted: 07/04/2023] [Indexed: 07/05/2023]
Abstract
Better control of molecule-electrode coupling (Γ) to minimize leakage current is an effective method to optimize the functionality of molecular diodes. Herein we embedded 5 isomers of phenypyridyl derivatives, each with an N atom placed at a different position, in two electrodes to fine-tune Γ between self-assembled monolayers (SAMs) and the top electrode of EGaIn (eutectic Ga-In terminating in Ga2 O3 ). Combined with electrical tunnelling results, characterizations of electronic structures, single-level model fittings, and DFT calculations, we found that the values of Γ of SAMs formed by these isomers could be regulated by nearly 10 times, thereby contributing to the leakage current changing over about two orders of magnitude and switching the isomers from resistors to diodes with a rectification ratio (r+ =|J(+1.5 V)/J(-1.5 V)|) exceeding 200. We demonstrated that the N atom placement can be chemically engineered to tune the resistive and rectifying properties of the molecular junctions, making it possible to convert molecular resistors into rectifiers. Our study provides fundamental insights into the role of isomerism in molecular electronics and offers a new avenue for designing functional molecular devices.
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Affiliation(s)
- Wuxian Peng
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Ningyue Chen
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Caiyun Wang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yu Xie
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Shengzhe Qiu
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Shuwei Li
- Center for Combustion Energy, Tsinghua University, Beijing, 100084, China
- School of Vehicle and Mobility, State Key Laboratory of Intelligent Green Vehicle and Mobility, Tsinghua University, Beijing, 100084, China
| | - Liang Zhang
- Center for Combustion Energy, Tsinghua University, Beijing, 100084, China
- School of Vehicle and Mobility, State Key Laboratory of Intelligent Green Vehicle and Mobility, Tsinghua University, Beijing, 100084, China
| | - Yuan Li
- Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China
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5
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Gupta R, Fereiro JA, Bayat A, Pritam A, Zharnikov M, Mondal PC. Nanoscale molecular rectifiers. Nat Rev Chem 2023; 7:106-122. [PMID: 37117915 DOI: 10.1038/s41570-022-00457-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2022] [Indexed: 01/15/2023]
Abstract
The use of molecules bridged between two electrodes as a stable rectifier is an important goal in molecular electronics. Until recently, however, and despite extensive experimental and theoretical work, many aspects of our fundamental understanding and practical challenges have remained unresolved and prevented the realization of such devices. Recent advances in custom-designed molecular systems with rectification ratios exceeding 105 have now made these systems potentially competitive with existing silicon-based devices. Here, we provide an overview and critical analysis of recent progress in molecular rectification within single molecules, self-assembled monolayers, molecular multilayers, heterostructures, and metal-organic frameworks and coordination polymers. Examples of conceptually important and best-performing systems are discussed, alongside their rectification mechanisms. We present an outlook for the field, as well as prospects for the commercialization of molecular rectifiers.
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6
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Zhao Z, Soni S, Lee T, Nijhuis CA, Xiang D. Smart Eutectic Gallium-Indium: From Properties to Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2203391. [PMID: 36036771 DOI: 10.1002/adma.202203391] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/30/2022] [Indexed: 05/27/2023]
Abstract
Eutectic gallium-indium (EGaIn), a liquid metal with a melting point close to or below room temperature, has attracted extensive attention in recent years due to its excellent properties such as fluidity, high conductivity, thermal conductivity, stretchability, self-healing capability, biocompatibility, and recyclability. These features of EGaIn can be adjusted by changing the experimental condition, and various composite materials with extended properties can be further obtained by mixing EGaIn with other materials. In this review, not only the are unique properties of EGaIn introduced, but also the working principles for the EGaIn-based devices are illustrated and the developments of EGaIn-related techniques are summarized. The applications of EGaIn in various fields, such as flexible electronics (sensors, antennas, electronic circuits), molecular electronics (molecular memory, opto-electronic switches, or reconfigurable junctions), energy catalysis (heat management, motors, generators, batteries), biomedical science (drug delivery, tumor therapy, bioimaging and neural interfaces) are reviewed. Finally, a critical discussion of the main challenges for the development of EGaIn-based techniques are discussed, and the potential applications in new fields are prospected.
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Affiliation(s)
- Zhibin Zhao
- Institute of Modern Optics and Center of Single Molecule Sciences, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, 300350, Tianjin, P. R. China
| | - Saurabh Soni
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands
| | - Takhee Lee
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Christian A Nijhuis
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands
| | - Dong Xiang
- Institute of Modern Optics and Center of Single Molecule Sciences, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, 300350, Tianjin, P. R. China
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7
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Sarkar S, Maiti SK. Helical Molecule as an Efficient Rectifier: Effects of Molecular Conformation and Transverse Electric Field. Chemphyschem 2022; 23:e202200485. [PMID: 35938540 DOI: 10.1002/cphc.202200485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/05/2022] [Indexed: 01/05/2023]
Abstract
The phenomenon of charge current rectification is critically investigated using a single stranded helical molecule in presence of transverse electric field. Two different helical molecules, DNA and protein, are taken into account to explore the specific roles of molecular conformation on rectification, which have not been addressed so far to the best of our concern. Sandwiching the molecular system within source and drain electrodes, we compute charge currents for two bias polarities and the degree of current rectification based on non-equilibrium Green's function formalism within a tight-binding framework. At non-zero electric field, site energies of the molecule are modulated in a cosine form, similar to the well known Aubry-André-Harper relation, resulting an atypical and fragmented energy band spectrum. The appearance of non-uniform site energies plays the central role for generating different currents in two bias polarities, and thus, the current rectification. We find that a high degree of current rectification can be established using the helical system and it becomes more effective for the protein molecule than the DNA one. At the end, the rectification operation considering a more general helical structure is discussed to make the present communication a self-contained one. Our proposition may provide a new route of getting controlled current rectification using similar kind of biological molecules and other tailor made helical geometries.
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Affiliation(s)
- Suparna Sarkar
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata, 700 108, India
| | - Santanu K Maiti
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata, 700 108, India
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8
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Khalid H, Opodi EM, Song X, Wang Z, Li B, Tian L, Yu X, Hu W. Modulated Structure and Rectification Properties of a Molecular Junction by a Mixed Self-Assembled Monolayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10893-10901. [PMID: 36007164 DOI: 10.1021/acs.langmuir.2c01751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The organization of the self-assembled monolayer (SAM) determines its electronic structure and so governs the charge transport process and device performance when adopted into a molecular device. We report a systematic study on the supramolecular structure and rectification performance of the ferrocene (11-ferrocenyl-1-undecanethiol, FUT) based SAM modulated by mixed SAM with inert 1-undecanethiol (C11SH) as diluent. We compared mixed SAMs by two different post assembly strategies, i.e., post assembly of C11SH on FUT SAM and post assembly of FUT on C11SH SAM. The organization and structure of FUT in the mixed SAM were extensively studied by cyclic voltammetry (CV) using the Laviron model. Rectification properties of the mixed SAM obtained using eutectic indium gallium (EGaIn) as the top electrode revealed that the magnitude and stability of the rectification ratio (RR) strongly correlated to not only the amount but also the phase structure and orientation of the FUT in the monolayer, resulting in a tunable RR and increased stability. The mixed monolayer achieved an increased performance relative to pure FUT by post assembling FUT on C11SH SAM, which formed an optimally dense and well-packed monolayer with the FUT head resting on the top of the alkane SAM.
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Affiliation(s)
- Hira Khalid
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Esther Martine Opodi
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Xianneng Song
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Ziyan Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Baili Li
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Lixian Tian
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Xi Yu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, School of Science, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
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9
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Dlugosch JM, Seim H, Bora A, Kamiyama T, Lieberman I, May F, Müller-Plathe F, Nefedov A, Prasad S, Resch S, Saller K, Seim C, Speckbacher M, Voges F, Tornow M, Kirsch P. Conductance Switching in Liquid Crystal-Inspired Self-Assembled Monolayer Junctions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:31044-31053. [PMID: 35776551 DOI: 10.1021/acsami.2c05264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We present the prototype of a ferroelectric tunnel junction (FTJ), which is based on a self-assembled monolayer (SAM) of small, functional molecules. These molecules have a structure similar to those of liquid crystals, and they are embedded between two solid-state electrodes. The SAM, which is deposited through a short sequence of simple fabrication steps, is extremely thin (3.4 ± 0.5 nm) and highly uniform. The functionality of the FTJ is ingrained in the chemical structure of the SAM components: a conformationally flexible dipole that can be reversibly reoriented in an electrical field. Thus, the SAM acts as an electrically switchable tunnel barrier. Fabricated stacks of Al/Al2O3/SAM/Pb/Ag with such a polar SAM show pronounced hysteretic, reversible conductance switching at voltages in the range of ±2-3 V, with a conductance ratio of the low and the high resistive states of up to 100. The switching mechanism is analyzed using a combination of quantum chemical, molecular dynamics, and tunneling resistance calculation methods. In contrast to more common, inorganic material-based FTJs, our approach using SAMs of small organic molecules allows for a high degree of functional complexity and diversity to be integrated by synthetic standard methods, while keeping the actual device fabrication process robust and simple. We expect that this technology can be further developed toward a level that would then allow its application in the field of information storage and processing, in particular for in-memory and neuromorphic computing architectures.
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Affiliation(s)
- Julian M Dlugosch
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Henning Seim
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Achyut Bora
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Takuya Kamiyama
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Itai Lieberman
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Falk May
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Alexei Nefedov
- Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Saurav Prasad
- Eduard-Zintl Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Sebastian Resch
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Kai Saller
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Christian Seim
- Xploraytion GmbH, Bismarckstraße 10-12, 10625 Berlin, Germany
| | - Maximilian Speckbacher
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
| | - Frank Voges
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Marc Tornow
- Molecular Electronics, Technical University of Munich, Hans-Piloty-Straße 1, 85748 Garching, Germany
- Fraunhofer Research Institution for Microsystems and Solid State Technologies (EMFT), Hansastraße 27d, 80686 München, Germany
| | - Peer Kirsch
- Electronics R&D, Merck KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
- Institute of Materials Science, Technical University of Darmstadt, Alarich-Weiss-Straße 2, 64297 Darmstadt, Germany
- Freiburg Materials Research Center (FMF), Albert Ludwig University Freiburg, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
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10
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Li P, Zhou L, Zhao C, Ju H, Gao Q, Si W, Cheng L, Hao J, Li M, Chen Y, Jia C, Guo X. Single-molecule nano-optoelectronics: insights from physics. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:086401. [PMID: 35623319 DOI: 10.1088/1361-6633/ac7401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Single-molecule optoelectronic devices promise a potential solution for miniaturization and functionalization of silicon-based microelectronic circuits in the future. For decades of its fast development, this field has made significant progress in the synthesis of optoelectronic materials, the fabrication of single-molecule devices and the realization of optoelectronic functions. On the other hand, single-molecule optoelectronic devices offer a reliable platform to investigate the intrinsic physical phenomena and regulation rules of matters at the single-molecule level. To further realize and regulate the optoelectronic functions toward practical applications, it is necessary to clarify the intrinsic physical mechanisms of single-molecule optoelectronic nanodevices. Here, we provide a timely review to survey the physical phenomena and laws involved in single-molecule optoelectronic materials and devices, including charge effects, spin effects, exciton effects, vibronic effects, structural and orbital effects. In particular, we will systematically summarize the basics of molecular optoelectronic materials, and the physical effects and manipulations of single-molecule optoelectronic nanodevices. In addition, fundamentals of single-molecule electronics, which are basic of single-molecule optoelectronics, can also be found in this review. At last, we tend to focus the discussion on the opportunities and challenges arising in the field of single-molecule optoelectronics, and propose further potential breakthroughs.
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Affiliation(s)
- Peihui Li
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Li Zhou
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Cong Zhao
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Hongyu Ju
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, People's Republic of China
| | - Qinghua Gao
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Wei Si
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Li Cheng
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Jie Hao
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Mengmeng Li
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Yijian Chen
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
| | - Chuancheng Jia
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
- Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, 292 Chengfu Road, Haidian District, Beijing 100871, People's Republic of China
| | - Xuefeng Guo
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, People's Republic of China
- Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, 292 Chengfu Road, Haidian District, Beijing 100871, People's Republic of China
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11
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Kang H, Cho SJ, Kong GD, Yoon HJ. Li-Ion Intercalation, Rectification, and Solid Electrolyte Interphase in Molecular Tunnel Junctions. NANO LETTERS 2022; 22:4956-4962. [PMID: 35666178 DOI: 10.1021/acs.nanolett.2c01669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This paper describes Li-ion intercalation into a pyrenyl-terminated self-assembled monolayer (SAM) on gold, inspired by the graphite anode in a Li-ion battery, and its effect on tunneling performance in a molecular junction incorporating the SAM. As the concentration of the Li-ion precursor ([LiPF6]) increased from 0 to 10-2 M, the rectification ratio increased to ∼102. Further experiments revealed that the intercalation-induced changes in the orientation of PYR group and in the HOMO energy level account for the enhanced rectification. Treatment with high concentrations of LiPF6 (from 10-2 to 100 M) yielded a considerable solid electrolyte interphase (SEI), mainly composed of LiF, on the surface of the SAM, resulting in the disappearance of rectification. This was attributed to renormalization of the HOMO level back to that of the intact SAM, caused by the SEI layer. Our work demonstrates the interplay among Li-ion intercalation, SEI, and tunneling in the molecular junction, benefiting the research of molecular electronics as well as SAM-based batteries.
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Affiliation(s)
- Hungu Kang
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Soo Jin Cho
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Gyu Don Kong
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, Korea
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12
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Carlotti M, Soni S, Kovalchuk A, Kumar S, Hofmann S, Chiechi RC. Empirical Parameter to Compare Molecule-Electrode Interfaces in Large-Area Molecular Junctions. ACS PHYSICAL CHEMISTRY AU 2022; 2:179-190. [PMID: 35637782 PMCID: PMC9136952 DOI: 10.1021/acsphyschemau.1c00029] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 12/03/2022]
Abstract
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This paper describes
a simple model for comparing the degree of
electronic coupling between molecules and electrodes across different
large-area molecular junctions. The resulting coupling parameter can
be obtained directly from current–voltage data or extracted
from published data without fitting. We demonstrate the generalizability
of this model by comparing over 40 different junctions comprising
different molecules and measured by different laboratories. The results
agree with existing models, reflect differences in mechanisms of charge
transport and rectification, and are predictive in cases where experimental
limitations preclude more sophisticated modeling. We also synthesized
a series of conjugated molecular wires, in which embedded dipoles
are varied systematically and at both molecule–electrode interfaces.
The resulting current–voltage characteristics vary in nonintuitive
ways that are not captured by existing models, but which produce trends
using our simple model, providing insights that are otherwise difficult
or impossible to explain. The utility of our model is its demonstrative
generalizability, which is why simple observables like tunneling decay
coefficients remain so widely used in molecular electronics despite
the existence of much more sophisticated models. Our model is complementary,
giving insights into molecule–electrode coupling across series
of molecules that can guide synthetic chemists in the design of new
molecular motifs, particularly in the context of devices comprising
large-area molecular junctions.
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Affiliation(s)
- Marco Carlotti
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Saurabh Soni
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andrii Kovalchuk
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Sumit Kumar
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Stephan Hofmann
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K
| | - Ryan C Chiechi
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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13
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Majhi J, Maiti SK, Ganguly S. Enhanced current rectification in graphene nanoribbons: effects of geometries and orientations of nanopores. NANOTECHNOLOGY 2022; 33:255704. [PMID: 35294939 DOI: 10.1088/1361-6528/ac5e6f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
We discuss the possibility of getting rectification operation in graphene nanoribbon (GNR). For a system to be a rectifier, it must be physically asymmetric and we induce the asymmetry in GNR by introducing nanopores. The rectification properties are discussed for differently structured nanopores. We find that shape and orientation of the nanopores are critical and sensitive to the degree of current rectification. As the choice of Fermi energy is crucial for obtaining significant current rectification, explicit dependence of Fermi energy on the degree of current rectification is also studied for a particular shape of the nanopore. Finally, the role of nanopore size and different spatial distributions of the electrostatic potential profile across the GNR are explored. The stability of the nanopores is also discussed with a possible solution. Given the simplicity of the proposed method and promising results, the present proposition may lead to a new route of getting current rectification in different kinds of materials where nanopores can be formed selectively.
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Affiliation(s)
- Joydeep Majhi
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108, India
| | - Santanu K Maiti
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108, India
| | - Sudin Ganguly
- Department of Physics, School of Applied Sciences, University of Science and Technology, Techno City, Kiling Road, Baridua 9th Mile, Ri-Bhoi, Meghalaya-793 101, India
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14
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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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15
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Xie Z, Bâldea I, Nguyen QV, Frisbie CD. Quantitative analysis of weak current rectification in molecular tunnel junctions subject to mechanical deformation reveals two different rectification mechanisms for oligophenylene thiols versus alkane thiols. NANOSCALE 2021; 13:16755-16768. [PMID: 34604892 DOI: 10.1039/d1nr04410a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Metal-molecule-metal junctions based on alkane thiol (CnT) and oligophenylene thiol (OPTn) self-assembled monolayers (SAMs) and Au electrodes are expected to exhibit similar electrical asymmetry, as both junctions have one chemisorbed Au-S contact and one physisorbed, van der Waals contact. Asymmetry is quantified by the current rectification ratio RR apparent in the current-voltage (I-V) characteristics. Here we show that RR < 1 for CnT and RR > 1 for OPTn junctions, in contrast to expectation, and further, that RR behaves very differently for CnT and OPTn junctions under mechanical extension using the conducting probe atomic force microscopy (CP-AFM) testbed. The analysis presented in this paper, which leverages results from the previously validated single level model and ab initio quantum chemical calculations, allows us to explain the puzzling experimental findings for CnT and OPTn in terms of different current rectification mechanisms. Specifically, in CnT-based junctions the Stark effect creates the HOMO level shifting necessary for rectification, while for OPTn junctions the level shift arises from position-dependent coupling of the HOMO wavefunction with the junction electrostatic potential profile. On the basis of these mechanisms, our quantum chemical calculations allow quantitative description of the impact of mechanical deformation on the measured current rectification. Additionally, our analysis, matched to experiment, facilitates direct estimation of the impact of intramolecular electrostatic screening on the junction potential profile. Overall, our examination of current rectification in benchmark molecular tunnel junctions illuminates key physical mechanisms at play in single step tunneling through molecules, and demonstrates the quantitative agreement that can be obtained between experiment and theory in these systems.
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Affiliation(s)
- Zuoti Xie
- Department of Materials Science and Engineering, Guangdong Technion-Israel Institute of Technology, Shantou, Guangdong, 515063, China.
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
| | - Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
| | - Quyen Van Nguyen
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
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16
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Li Y, Root SE, Belding L, Park J, Rawson J, Yoon HJ, Baghbanzadeh M, Rothemund P, Whitesides GM. Characterizing Chelation at Surfaces by Charge Tunneling. J Am Chem Soc 2021; 143:5967-5977. [PMID: 33834784 DOI: 10.1021/jacs.1c01800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes a surface analysis technique that uses the "EGaIn junction" to measure tunneling current densities (J(V), amps/cm2) through self-assembled monolayers (SAMs) terminated in a chelating group and incorporating different transition metal ions. Comparisons of J(V) measurements between bare chelating groups and chelates are used to characterize the composition of the SAM and infer the dissociation constant (Kd, mol/L), as well as kinetic rate constants (koff, L/mol·s; kon, 1/s) of the reversible chelate-metal reaction. To demonstrate the concept, SAMs of 11-(4-methyl-2,2'-bipyrid-4'-yl (bpy))undecanethiol (HS(CH2)11bpy) were incubated within ethanol solutions of metal salts. After rinsing and drying the surface, measurements of current as a function of incubation time and concentration in solution are used to infer koff, kon, and Kd. X-ray photoelectron spectroscopy (XPS) provides an independent measure of surface composition to confirm inferences from J(V) measurements. Our experiments establish that (i) bound metal ions are stable to the rinsing step as long as the rinsing time, τrinse ≪ 1koff; (ii) the bound metal ions increase the current density at the negative bias and reduce the rectification observed with free bpy terminal groups; (iii) the current density as a function of the concentration of metal ions in solution follows a sigmoidal curve; and (iv) the values of Kd measured using J(V) are comparable to those measured using XPS, but larger than those measured in solution. The EGaIn junction, thus, provides a new tool for the analysis of the composition of the surfaces that undergo reversible chemical reactions with species in solution.
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Affiliation(s)
- Yuan Li
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States.,Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Samuel E Root
- 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
| | - Junwoo Park
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Jeff Rawson
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Philipp Rothemund
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, 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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17
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Kong GD, Song H, Yoon S, Kang H, Chang R, Yoon HJ. Interstitially Mixed Self-Assembled Monolayers Enhance Electrical Stability of Molecular Junctions. NANO LETTERS 2021; 21:3162-3169. [PMID: 33797252 DOI: 10.1021/acs.nanolett.1c00406] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Electrical breakdown is a critical problem in electronics. In molecular electronics, it becomes more problematic because ultrathin molecular monolayers have delicate and defective structures and exhibit intrinsically low breakdown voltages, which limit device performances. Here, we show that interstitially mixed self-assembled monolayers (imSAMs) remarkably enhance electrical stability of molecular-scale electronic devices without deteriorating function and reliability. The SAM of the sterically bulky matrix (SC11BIPY rectifier) molecule is diluted with a skinny reinforcement (SCn) molecule via the new approach, so-called repeated surface exchange of molecules (ReSEM). Combined experiments and simulations reveal that the ReSEM yields imSAMs wherein interstices between the matrix molecules are filled with the reinforcement molecules and leads to significantly enhanced breakdown voltage inaccessible by traditional pure or mixed SAMs. Thanks to this, bias-driven disappearance and inversion of rectification is unprecedentedly observed. Our work may help to overcome the shortcoming of SAM's instability and expand the functionalities.
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Affiliation(s)
- Gyu Don Kong
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hyunsun Song
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Seungmin Yoon
- Department of Chemistry, Kwangwoon University, Seoul 01897, Korea
| | - Hungu Kang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Rakwoo Chang
- Department of Applied Chemistry, University of Seoul, Seoul 02543, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
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18
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Kang S, Byeon SE, Yoon HJ. N
‐Heterocyclic
Carbene Anchors in Electronics Applications. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12261] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Seohyun Kang
- Department of Chemistry Korea University Seoul 02841 Republic of Korea
| | - Seo Eun Byeon
- Department of Chemistry Korea University Seoul 02841 Republic of Korea
| | - Hyo Jae Yoon
- Department of Chemistry Korea University Seoul 02841 Republic of Korea
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19
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Lee HJ, Cho SJ, Kang H, He X, Yoon HJ. Achieving Ultralow, Zero, and Inverted Tunneling Attenuation Coefficients in Molecular Wires with Extended Conjugation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005711. [PMID: 33543557 DOI: 10.1002/smll.202005711] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/22/2020] [Indexed: 06/12/2023]
Abstract
Molecular tunnel junctions are organic devices miniaturized to the molecular scale. They serve as a versatile toolbox that can systematically examine charge transport behaviors at the atomic level. The electrical conductance of the molecular wire that bridges the two electrodes in a junction is significantly influenced by its chemical structure, and an intrinsically poor conductance is a major barrier for practical applications toward integrating individual molecules into electronic circuitry. Therefore, highly conjugated molecular wires are attractive as active components for the next-generation electronic devices, owing to the narrow highest occupied molecular orbital-lowest occupied molecular orbital gaps provided by their extended π-building blocks. This article aims to highlight the significance of highly conductive molecular wires in molecular electronics, the structures of which are inspired from conductive organic polymers, and presents a body of discussion on molecular wires exhibiting ultralow, zero, or inverted attenuation of tunneling probability at different lengths, along with future directions.
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Affiliation(s)
- Hyun Ju Lee
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Soo Jin Cho
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Hungu Kang
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Xin He
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
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20
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Gillet A, Cher S, Tassé M, Blon T, Alves S, Izzet G, Chaudret B, Proust A, Demont P, Volatron F, Tricard S. Polarizability is a key parameter for molecular electronics. NANOSCALE HORIZONS 2021; 6:271-276. [PMID: 33507203 DOI: 10.1039/d0nh00583e] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Identifying descriptors that govern charge transport in molecular electronics is of prime importance for the elaboration of devices. The effects of molecule characteristics, such as size, bulkiness or charge, have been widely reported. Herein, we show that the molecule polarizability can be a crucial parameter to consider. To this end, platinum nanoparticle self-assemblies (PtNP SAs) are synthesized in solution, including a series of polyoxometalates (POMs). The charge of the POM unit can be modified according to the nature of the central heteroatom while keeping its size constant. POM hybrids that display remote terminal thiol functions strongly anchor the PtNP surface to form robust SAs. IV curves, recorded by conductive AFM, show a decrease in Coulomb blockade as the dielectric constant of the POMs increases. In this system, charge transport across molecular junctions can be interpreted as variations in polarizability, which is directly related to the dielectric constant.
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Affiliation(s)
- Angélique Gillet
- Laboratoire de Physique et Chimie des Nano-Objets, INSA, CNRS, Université de Toulouse, Toulouse, France.
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21
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Belding L, Root SE, Li Y, Park J, Baghbanzadeh M, Rojas E, Pieters PF, Yoon HJ, Whitesides GM. Conformation, and Charge Tunneling through Molecules in SAMs. J Am Chem Soc 2021; 143:3481-3493. [DOI: 10.1021/jacs.0c12571] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- 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
| | - Yuan Li
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Junwoo Park
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Edwin Rojas
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Priscilla F. Pieters
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - George M. Whitesides
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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22
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Kang H, Kong GD, Yoon HJ. Solid State Dilution Controls Marcus Inverted Transport in Rectifying Molecular Junctions. J Phys Chem Lett 2021; 12:982-988. [PMID: 33464915 DOI: 10.1021/acs.jpclett.0c03251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Traditional Marcus theory accounts for electron transfer reactions in solutions, and the polarity of solvent molecule matters for them. How such an environment polarity affects electron transfer reactions in solid-state devices, however, remains uncertain. This paper describes how the Marcus inverted charge transport is influenced by solid-state molecular dilution in large-area tunneling junctions. A monolayer of 2,2'-bipyridyl terminated n-alkanethiolate (SC11BIPY), which rectifies currents via electron hopping within the inverted regime, is diluted with n-alkanethiolate (SCn) of different lengths (n = 8, 10, or 18) or at different surface mole fractions. The dilution introduces nonpolar environments within the monolayer, hinders stabilization of charged BIPY species upon electron hopping, and pushes the equilibrium of BIPY ⇄ BIPY•- process toward the reverse direction. Our work demonstrates that solid-state molecular dilution permits systematic control of the environment polarity of active component in nanoscale devices, much like solvent polarity control in solution, and their performances.
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Affiliation(s)
- Hungu Kang
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Gyu Don Kong
- Department of Chemistry, Korea University, Seoul, 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, Korea
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23
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Park J, Belding L, Yuan L, Mousavi MPS, Root SE, Yoon HJ, Whitesides GM. Rectification in Molecular Tunneling Junctions Based on Alkanethiolates with Bipyridine-Metal Complexes. J Am Chem Soc 2021; 143:2156-2163. [PMID: 33480255 DOI: 10.1021/jacs.0c12641] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This paper addresses the mechanism for rectification in molecular tunneling junctions based on alkanethiolates terminated by a bipyridine group complexed with a metal ion, that is, having the structure AuTS-S(CH2)11BIPY-MCl2 (where M = Co or Cu) with a eutectic indium-gallium alloy top contact (EGaIn, 75.5% Ga 24.5% In). Here, AuTS-S(CH2)11BIPY is a self-assembled monolayer (SAM) of an alkanethiolate with 4-methyl-2,2'-bipyridine (BIPY) head groups, on template-stripped gold (AuTS). When the SAM is exposed to cobalt(II) chloride, SAMs of the form AuTS-S(CH2)11BIPY-CoCl2 rectify current with a rectification ratio of r+ = 82.0 at ±1.0 V. The rectification, however, disappears (r+ = 1.0) when the SAM is exposed to copper(II) chloride instead of cobalt. We draw the following conclusions from our experimental results: (i) AuTS-S(CH2)11BIPY-CoCl2 junctions rectify current because only at positive bias (+1.0 V) is there an accessible molecular orbital (the LUMO) on the BIPY-CoCl2 moiety, while at negative bias (-1.0 V), neither the energy level of the HOMO or the LUMO lies between the Fermi levels of the electrodes. (ii) AuTS-S(CH2)11BIPY-CuCl2 junctions do not rectify current because there is an accessible molecular orbital on the BIPY-CuCl2 moiety at both negative and positive bias (the HOMO is accessible at negative bias, and the LUMO is accessible at positive bias). The difference in accessibility of the HOMO levels at -1.0 V causes charge transfer-at negative bias-to take place via Fowler-Nordheim tunneling in BIPY-CoCl2 junctions, and via direct tunneling in BIPY-CuCl2 junctions. This difference in tunneling mechanism at negative bias is the origin of the difference in rectification ratio between BIPY-CoCl2 and BIPY-CuCl2 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
| | - Lee Belding
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Li Yuan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Maral P S Mousavi
- 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
| | - Hyo Jae Yoon
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States.,Department of Chemistry, Korea University, Seoul 02841, Korea
| | - George M Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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24
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Kang H, Kong GD, Byeon SE, Yang S, Kim JW, Yoon HJ. Interplay of Fermi Level Pinning, Marcus Inverted Transport, and Orbital Gating in Molecular Tunneling Junctions. J Phys Chem Lett 2020; 11:8597-8603. [PMID: 32976711 DOI: 10.1021/acs.jpclett.0c02509] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This Letter examines the interplay of important tunneling mechanisms-Fermi level pinning, Marcus inverted transport, and orbital gating-in a molecular rectifier. The temperature dependence of the rectifying molecular junction containing 2,2'-bipyridyl terminated n-alkanethiolate was investigated. A bell-shaped trend of activation energy as a function of applied bias evidenced the dominant occurrence of unusual Marcus inverted transport, while retention of rectification at low temperatures implied that the rectification obeyed the resonant tunneling regime. The results allowed reconciling two separately developed transport models, Marcus-Landauer energetics and Fermi level pinning-based rectification. Our work shows that the internal orbital gating can be substituted with the pinning effect, which pushes the transport mechanism into the Marcus inverted regime.
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Affiliation(s)
- Hungu Kang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Gyu Don Kong
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Seo Eun Byeon
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Sena Yang
- Korea Research Institute of Standards and Science (KRISS), Daejeon 34113, Korea
| | - Jeong Won Kim
- Korea Research Institute of Standards and Science (KRISS), Daejeon 34113, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
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25
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Sanad MF, Shalan AE, Abdellatif SO, Serea ESA, Adly MS, Ahsan MA. Thermoelectric Energy Harvesters: A Review of Recent Developments in Materials and Devices for Different Potential Applications. Top Curr Chem (Cham) 2020; 378:48. [PMID: 33037928 DOI: 10.1007/s41061-020-00310-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/10/2020] [Indexed: 11/30/2022]
Abstract
The thermoelectric effect encompasses three different effects, i.e. Seebeck effect, Peltier effect, and Thomson effect, which are considered as thermally activated materials that alter directions in smart materials. It is currently considered one of the most challenging green energy harvesting mechanisms among researchers. The ability to utilize waste thermal energy that is generated by different applications promotes the use of thermoelectric harvesters across a wide range of applications. This review illustrates the different attempts to fabricate efficient, robust and sustainable thermoelectric harvesters, considering the material selection, characterization, device fabrication and potential applications. Thermoelectric harvesters with a wide range of output power generated reaching the milliwatt range have been considered in this work, with a special focus on the main advantages and disadvantages in these devices. Additionally, this review presents various studies reported in the literature on the design and fabrication of thermoelectric harvesters and highlights their potential applications. In order to increase the efficiency of equipment and processes, the generation of thermoelectricity via thermoelectric materials is achieved through the harvesting of residual energy. The review discusses the main challenges in the fabrication process associated with thermoelectric harvester implementation, as well as the considerable advantages of the proposed devices. The use of thermoelectric harvesters in a wide range of applications where waste thermal energy is used and the impact of the thermoelectric harvesters is also highlighted in this review.
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Affiliation(s)
- Mohamed Fathi Sanad
- FabLab, Centre for Emerging Learning Technologies (CELT), Electrical Engineering Department, The British University in Egypt (BUE), Cairo, 11387, Egypt
| | - Ahmed Esmail Shalan
- Central Metallurgical Research and Development Institute (CMRDI), P.O. Box 87, Helwan, 11421, Cairo, Egypt. .,BCMaterials-Basque Center for Materials, Applications and Nanostructures, Martina Casiano, UPV/EHU Science Park, Barrio Sarriena S/N, 48940, Leioa, Spain.
| | - Sameh O Abdellatif
- FabLab, Centre for Emerging Learning Technologies (CELT), Electrical Engineering Department, The British University in Egypt (BUE), Cairo, 11387, Egypt
| | - Esraa Samy Abu Serea
- Chemistry and Biochemistry Department, Faculty of Science, Cairo University, Cairo, Egypt.,BCMaterials-Basque Center for Materials, Applications and Nanostructures, Martina Casiano, UPV/EHU Science Park, Barrio Sarriena S/N, 48940, Leioa, Spain
| | - Mina Shawky Adly
- Chemistry Department, Faculty of Science, Mansoura University, Mansoura, Egypt.,Department of Chemistry, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Md Ariful Ahsan
- The University of Texas at El Paso, 500 W University Ave, El Paso, TX, 79968, USA
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26
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Song H, Kim T, Kang S, Jin H, Lee K, Yoon HJ. Ga-Based Liquid Metal Micro/Nanoparticles: Recent Advances and Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1903391. [PMID: 31583849 DOI: 10.1002/smll.201903391] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/21/2019] [Indexed: 05/20/2023]
Abstract
Liquid metals are emerging as fluidic inorganic materials in various research fields. Micro- and nanoparticles of Ga and its alloys have received particular attention in the last decade due to their non toxicity and accessibility in ambient conditions as well as their interesting chemical, physical, mechanical, and electrical properties. Unique features such as a fluidic nature and self-passivating oxide skin make Ga-based liquid metal particles (LMPs) distinguishable from conventional inorganic particles in the context of synthesis and applications. Here, recent advances in the bottom-up and top-down synthetic methods of Ga-based LMPs, their physicochemical properties, and their applications are summarized. Finally, the current status of the LMPs is highlighted and perspectives on future directions are also provided.
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Affiliation(s)
- Hyunsun Song
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Taekyung Kim
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Seohyun Kang
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Haneul Jin
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Kwangyeol Lee
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Hyo Jae Yoon
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
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27
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Huang X, Chen J, Yan C, Shao H. Probing a Reversible Cationic Switch on a Mixed Self-Assembled Monolayer Using Scanning Electrochemical Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10772-10779. [PMID: 31361491 DOI: 10.1021/acs.langmuir.9b01429] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Probing a switch on biomimic membrane surfaces would offer some references to the research on permeability of cytomembranes. In this work, a mixed 11-mercaptoundecanoic acid/1-undecanethiol self-assembled monolayer (MUA/UT SAM) was constructed as a model of a biomembrane. In this mixed SAM, the MUA molecules work as functional parts for the switch and the UT molecules work as diluents. The surface coverage, wetting property, and pKa of this mixed SAM all have been well-inspected. The mixed SAM exhibits excellent switchable properties for cations, which is well-monitored by scanning electrochemical microscopy. When the pH of a solution is higher than the pKa, protons would stimulate a shift of dissociation equilibrium of terminal carboxyl groups. The dissociated carboxylate ions would lead to a switch on the state of the SAM. Otherwise, the SAM shows an off state when the pH is lower than the pKa. In addition, the repeatability, applicability, and the mechanism of the switch all have been well-evaluated.
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Affiliation(s)
- Ximing Huang
- Beijing Key Laboratory of Photoelectronic and Electrophotonic Conversion Materials, Key Laboratory of Cluster Science (Ministry of Education), School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China
| | - Jingchao Chen
- Beijing Key Laboratory of Photoelectronic and Electrophotonic Conversion Materials, Key Laboratory of Cluster Science (Ministry of Education), School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China
| | - Chunxia Yan
- Beijing Key Laboratory of Photoelectronic and Electrophotonic Conversion Materials, Key Laboratory of Cluster Science (Ministry of Education), School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China
| | - Huibo Shao
- Beijing Key Laboratory of Photoelectronic and Electrophotonic Conversion Materials, Key Laboratory of Cluster Science (Ministry of Education), School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China
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Baghbanzadeh M, Belding L, Yuan L, Park J, Al-Sayah MH, Bowers CM, Whitesides GM. Dipole-Induced Rectification Across AgTS/SAM//Ga2O3/EGaIn Junctions. J Am Chem Soc 2019; 141:8969-8980. [DOI: 10.1021/jacs.9b02891] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Mostafa Baghbanzadeh
- 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
| | - Li Yuan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Junwoo Park
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Mohammad H. Al-Sayah
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Department of Biology, Chemistry and Environmental Sciences, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates
| | - Carleen M. Bowers
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - George M. Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Kavli Institute for Bionano Science and Technology, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, United States
- Wyss Institute of Biologically Inspired Engineering, Harvard University, 60 Oxford Street, Cambridge, Massachusetts 02138, United States
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29
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Cho SJ, Kong GD, Park S, Park J, Byeon SE, Kim T, Yoon HJ. Molecularly Controlled Stark Effect Induces Significant Rectification in Polycyclic-Aromatic-Hydrocarbon-Terminated n-Alkanethiolates. NANO LETTERS 2019; 19:545-553. [PMID: 30582703 DOI: 10.1021/acs.nanolett.8b04488] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The variation of the electronic structure of individual molecules as a function of the applied bias matters for the performance of molecular and organic electronic devices. Understanding the structure-electric-field relationship, however, remains a challenge because of the lack of in-operando spectroscopic technique and complexity arising from the ill-defined on-surface structure of molecules and organic-electrode interfaces within devices. We report that a reliable and reproducible molecular diode can be achieved by control of the conjugation length in polycyclic-aromatic-hydrocarbon (PAH)-terminated n-alkanethiolate (denoted as SC11PAH), incorporated into liquid-metal-based large-area tunnel junctions in the form of a self-assembled monolayer. By taking advantage of the structural simplicity and tunability of SC11PAH and the high-yielding feature of the junction technique, we demonstrate that the increase in the conjugation length of the PAH terminal group leads to a significant rectification ratio up to ∼1.7 × 102 at ±740 mV. Further study suggests that the Stark shift of the molecular energy resonance of the PAH breaks the symmetry of the energy topography across the junction and induces rectification in a temperature-independent charge-transport regime.
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Affiliation(s)
- Soo Jin Cho
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Gyu Don Kong
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Sohyun Park
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Jeongwoo Park
- Department of Physics , Hankuk University of Foreign Studies , Yongin 449-791 , Korea
| | - Seo Eun Byeon
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Taekyeong Kim
- Department of Physics , Hankuk University of Foreign Studies , Yongin 449-791 , Korea
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
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30
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Kang S, Park S, Kang H, Cho SJ, Song H, Yoon HJ. Tunneling and thermoelectric characteristics of N-heterocyclic carbene-based large-area molecular junctions. Chem Commun (Camb) 2019; 55:8780-8783. [DOI: 10.1039/c9cc01585j] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tunneling and thermoelectric characteristics of NHC-based large-area junctions were demonstrated for the first time.
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Affiliation(s)
- Seohyun Kang
- Department of Chemistry
- Korea University
- Seoul
- South Korea
| | - Sohyun Park
- Department of Chemistry
- Korea University
- Seoul
- South Korea
| | - Hungu Kang
- Department of Chemistry
- Korea University
- Seoul
- South Korea
| | - Soo Jin Cho
- Department of Chemistry
- Korea University
- Seoul
- South Korea
| | - Hyunsun Song
- Department of Chemistry
- Korea University
- Seoul
- South Korea
| | - Hyo Jae Yoon
- Department of Chemistry
- Korea University
- Seoul
- South Korea
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31
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Park S, Yoon HJ. New Approach for Large-Area Thermoelectric Junctions with a Liquid Eutectic Gallium-Indium Electrode. NANO LETTERS 2018; 18:7715-7718. [PMID: 30418032 DOI: 10.1021/acs.nanolett.8b03404] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A challenge in organic thermoelectrics is to relate thermoelectric performance of devices to the chemical and electronic structures of organic components inside them on a molecular scale. To this end, a reliable and reproducible platform relevant to molecular-level thermoelectric measurements is essentially needed. This paper shows a new, efficient approach for thermoelectric characterization of a large area of molecular monolayers using liquid eutectic gallium-indium (EGaIn). A cone-shaped EGaIn microelectrode permits access to noninvasive, reversible top-contact formation onto organic surfaces in ambient conditions, high yields of working devices (up to 97%), and thus statistically sufficient thermoelectric data sets (∼6000 data per sample in a few hours). We here estimated thermopowers of EGaIn (3.4 ± 0.1 μV/K) and the Ga2O3 layer (3.4 ± 0.2 μV/K) on the EGaIn conical tip and successfully validated our platform with widely studied molecules, oligophenylenethiolates. Our approach will open the door to thermoelectric large-area molecular junctions.
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Affiliation(s)
- Sohyun Park
- Department of Chemistry , Korea University , Seoul 02841 , Korea
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seoul 02841 , Korea
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32
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Baghbanzadeh M, Pieters PF, Yuan L, Collison D, Whitesides GM. The Rate of Charge Tunneling in EGaIn Junctions Is Not Sensitive to Halogen Substituents at the Self-Assembled Monolayer//Ga 2O 3 Interface. ACS NANO 2018; 12:10221-10230. [PMID: 30226988 DOI: 10.1021/acsnano.8b05217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This paper describes experiments that are designed to test the influence of terminal groups incorporating carbon-halogen bonds on the current density (by hole tunneling) across self-assembled monolayer (SAM)-based junctions of the form MTS/S(CH2)9NHCOCH nX3- n//Ga2O3/EGaIn (where M = Ag and Au and X = CH3, F, Cl, Br, I). Within the limits of statistical significance, these rates of tunneling are insensitive to the nature of the terminal group at the interface between the SAM and the Ga2O3. The results are relevant to the origin of an apparent inconsistency in the literature concerning the influence of halogen atoms at the SAM//electrode interface on the tunneling current density.
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Affiliation(s)
- Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Priscilla F Pieters
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Li Yuan
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Darrell Collison
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - George M Whitesides
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Kavli Institute for Bionano Science and Technology , Harvard University 29 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Wyss Institute of Biologically Inspired Engineering , 60 Oxford Street , Cambridge , Massachusetts 02138 , United States
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33
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Souto M, Díez-Cabanes V, Yuan L, Kyvik AR, Ratera I, Nijhuis CA, Cornil J, Veciana J. Influence of the donor unit on the rectification ratio in tunnel junctions based on donor-acceptor SAMs using PTM units as acceptors. Phys Chem Chem Phys 2018; 20:25638-25647. [PMID: 30288535 DOI: 10.1039/c8cp05488f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Dyads formed by an electron donor unit (D) covalently linked to an electron acceptor (A) by an organic bridge are promising materials as molecular rectifiers. Very recently, we have reported the charge transport measurements across self-assembled monolayers (SAMs) of two D-A systems consisting of the ferrocene (Fc) electron-donor linked to a polychlorotriphenylmethane (PTM) electron-acceptor in its non-radical (SAM 1) and radical (SAM 2) forms. Interestingly, we observed that the non-radical SAM 1 showed rectification behavior of 2 orders of magnitude higher than its radical analogue dyad 2. In order to study the influence of the donor unit on the transport properties, we report herein the synthesis and characterization of two new D-A SAMs in which the electron-donor Fc unit is replaced by a tetrathiafulvalene (TTF) moiety linked to the PTM unit in its non-radical (SAM 3) and radical (SAM 4) forms. The observed decrease in the rectification ratio and increased current density for TTF-PTM based SAMs 3 and 4 in comparison to Fc-PTM based SAMs 1 and 2 are explained, supported by theoretical calculations, by significant changes in the electronic and supramolecular structures.
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Affiliation(s)
- Manuel Souto
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)/CIBER-BBN, Campus Universitari de UAB, 08193 Cerdanyola del Vallès (Barcelona), Spain.
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34
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Um HJ, Kong GD, Yoon HJ. Thermally Controlled Phase Transition of Low-Melting Electrode for Wetting-Based Spontaneous Top Contact in Molecular Tunnel Junction. ACS APPLIED MATERIALS & INTERFACES 2018; 10:34758-34764. [PMID: 30215250 DOI: 10.1021/acsami.8b12312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Top contacts for molecular-scale electronic devices should exhibit reliable and reproducible electronic performance. This goal is challenging and difficult to achieve because metals are usually evaporated under high-energy conditions that easily damage delicate organic surfaces, and complicated nanofabrication processes are needed for achieving geometrically defined small contact areas. Soft top contacts that are made by users under ambient conditions can circumvent this problem but often show user-dependence. This paper describes that thermally controlled phase transition (TCPT) of low-melting (29.76 °C) electrode comprising gallium covered with a self-passivating oxide layer could be useful to form reliable, spontaneous (i.e., user-independent) top contacts over delicate ultrathin organic films such as self-assembled monolayers (SAMs). As a proof-of-concept, we demonstrate that the phase transition from solid to non-Newtonian liquid for gallium electrode is tuned under mild thermal conditions (room temperature to ∼50 °C), which does not damage the organic component and ensures conformal, geometrically defined contacts. The contact force predominantly depends on wetting of compliant liquid gallium onto SAMs, upon heating, not on user-pressure. Indeed, the TCPT-based large-area tunnel junctions on SAMs of n-mercaptoalkanoic acids yield markedly narrow dispersion of tunneling current density (σlog| J| = 0.04-0.19) and tunneling attenuation coefficient (β = 0.92 ± 0.02 nC-1) consistent with the literature value. We envisage that our approach can be harnessed to accomplish liquid metal-based tunnel junctions without significant user-to-user variations and hence useful for reliable understanding of charge transport across molecules and practical applications.
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Affiliation(s)
- Hyo Jeong Um
- Department of Chemistry , Korea University , Seoul 02841 , Korea
| | - Gyu Don Kong
- Department of Chemistry , Korea University , Seoul 02841 , Korea
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seoul 02841 , Korea
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35
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Chen J, Kim M, Gathiaka S, Cho SJ, Kundu S, Yoon HJ, Thuo MM. Understanding Keesom Interactions in Monolayer-Based Large-Area Tunneling Junctions. J Phys Chem Lett 2018; 9:5078-5085. [PMID: 30126267 DOI: 10.1021/acs.jpclett.8b01731] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Charge transport across self-assembled monolayers (SAMs) has been widely studied. Discrepancies of charge tunneling data that arise from various studies, however, call for efforts to develop new statistical analytical approaches to understand charge tunneling across SAMs. Structure-property studies on charge tunneling across SAM-based junctions have largely been through comparison of average tunneling rates and associated variance. These early moments (especially the average) are dominated by barrier width-a static property of the junction. In this work, we show that analysis of higher statistical moments (skewness and kurtosis) reveals the dynamic nature of the tunnel junction. Intramolecular Keesom (dipole-dipole) interactions dynamically fluctuate with bias as dictated by stereoelectronic limitations. Analyzing variance in the distribution of tunneling data instead of the first statistical moment (average), for a series of n-alkanethiols containing internal amide and aromatic terminal groups, we observe that the direction of dipole moments affects molecule-electrode coupling. An applied bias induces changes in the tunneling probability, affecting the distribution of tunneling paths in large-area molecular junctions.
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Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering , Iowa State University , Ames , Iowa 50010 , United States
| | - Miso Kim
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Symon Gathiaka
- School of Pharmacy and Pharmaceutical Science , University of California , La Jolla , California 92093-0657 , United States
| | - Soo Jin Cho
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Souvik Kundu
- Department of Electrical and Computer Engineering , Iowa State University , Ames , Iowa 50010 , United States
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Martin M Thuo
- Department of Materials Science and Engineering , Iowa State University , Ames , Iowa 50010 , United States
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36
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Kong GD, Jin J, Thuo M, Song H, Joung JF, Park S, Yoon HJ. Elucidating the Role of Molecule–Electrode Interfacial Defects in Charge Tunneling Characteristics of Large-Area Junctions. J Am Chem Soc 2018; 140:12303-12307. [DOI: 10.1021/jacs.8b08146] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gyu Don Kong
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Junji Jin
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Hyunsun Song
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | | | - Sungnam Park
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
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37
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Jin J, Kong GD, Yoon HJ. Deconvolution of Tunneling Current in Large-Area Junctions Formed with Mixed Self-Assembled Monolayers. J Phys Chem Lett 2018; 9:4578-4583. [PMID: 30063358 DOI: 10.1021/acs.jpclett.8b01997] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Whereas single-component self-assembled monolayers (SAMs) have served widely as organic components in molecular and organic electronics, how the performance of the device is influenced by the heterogeneity of monolayers has been little understood. This paper describes charge transport by quantum tunneling across mixed SAMs of n-alkanethiolates of different lengths formed on ultraflat template-stripped gold substrate. Electrical characterization using liquid metal comprising eutectic gallium-indium alloy reveals that the surface topography of monolayer largely depends on the difference in length between the thiolates and is translated into distribution of tunneling current density. As the length difference is more significant, more phase segregation takes place, leading to an increase in the modality of Gaussian fitting curves. Consequently, statistical analysis permits access to deconvolution of tunneling currents, mirroring the phase-segregated surface. Our work provides an insight into the role of surface topography in the performance of molecular-scale electronic devices.
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Affiliation(s)
- Junji Jin
- Department of Chemistry , Korea University , Seoul 02841 , Korea
| | - Gyu Don Kong
- Department of Chemistry , Korea University , Seoul 02841 , Korea
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seoul 02841 , Korea
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38
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Sierra MA, Sánchez D, Garrigues AR, Del Barco E, Wang L, Nijhuis CA. How to distinguish between interacting and noninteracting molecules in tunnel junctions. NANOSCALE 2018; 10:3904-3910. [PMID: 29423488 DOI: 10.1039/c7nr05739c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recent experiments demonstrate a temperature control of the electric conduction through a ferrocene-based molecular junction. Here we examine the results in view of determining means to distinguish between transport through single-particle molecular levels or via transport channels split by Coulomb repulsion. Both transport mechanisms are similar in molecular junctions given the similarities between molecular intralevel energies and the charging energy. We propose an experimentally testable way to identify the main transport process. By applying a magnetic field to the molecule, we observe that an interacting theory predicts a shift of the conductance resonances of the molecule whereas in the noninteracting case each resonance is split into two peaks. The interaction model works well in explaining our experimental results obtained in a ferrocene-based single-molecule junction, where the charge degeneracy peaks shift (but do not split) under the action of an applied 7-Tesla magnetic field. This method is useful for a proper characterization of the transport properties of molecular tunnel junctions.
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Affiliation(s)
- Miguel A Sierra
- Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), Palma de Mallorca, Spain.
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39
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Chen J, Wang Z, Oyola-Reynoso S, Thuo MM. Properties of Self-Assembled Monolayers Revealed via Inverse Tensiometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13451-13467. [PMID: 28777587 DOI: 10.1021/acs.langmuir.7b01937] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembled monolayers (SAMs) have emerged as a simple platform technology and hence have been broadly studied. With advances in state-of-the-art fabrication and characterization methods, new insights into SAM structure and related properties have been delineated, albeit with some discrepancies and/or incoherencies. Some discrepancies, especially between experimental and theoretical work, are in part due to the misunderstanding of subtle structural features such as phase evolution and SAM quality. Recent work has, however, shown that simple techniques, such as the measurement of static contact angles, can be used to delineate otherwise complex properties of the SAM, especially when complemented by other more advanced techniques. In this article, we highlight the effect of nanoscale substrate asperities and molecular chain length on the SAM structure and associated properties. First, surfaces with tunable roughness are prepared on both Au and Ag, and their corresponding n-alkanethiolate SAMs are characterized through wetting and spectroscopy. From these data, chain-length- and substrate-morphology-dependent limits to the odd-even effect (structure and properties vary with the number of carbons in the molecules and the nature of the substrate), parametrization of gauche defect densities, and structural phase evolution (liquidlike, waxy, crystalline interfaces) are deduced. An evaluation of the correlation between the effect of roughness and the components of surface tension (polar-γp and dispersive-γd) reveals that wetting, at nanoscale rough surfaces, evolves proportionally with the ratio of the two components of surface tension. The evolution of conformational order is captured over a range of molecular lengths and parametrized through a dimensionless number, χc. By deploying a well-known tensiometry technique (herein the liquid is used to characterize the solid, hence the term inverse tensiometry) to characterize SAMs, we demonstrate that complex molecular-level phenomena in SAMs can be understood through simplicity.
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Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Martin M Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
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40
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Byeon SE, Kim M, Yoon HJ. Maskless Arbitrary Writing of Molecular Tunnel Junctions. ACS APPLIED MATERIALS & INTERFACES 2017; 9:40556-40563. [PMID: 29087173 DOI: 10.1021/acsami.7b14347] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Since fabricating geometrically well-defined, noninvasive, and compliant electrical contacts over molecular monolayers is difficult, creating molecular-scale electronic devices that function in high yield with good reproducibility is challenging. Moreover, none of the previously reported methods to form organic-electrode contacts at the nanometer and micrometer scales have resulted in directly addressable contacts in an untethered form under ambient conditions without the use of cumbersome equipment and nanolithography. Here we show that in situ encapsulation of a liquid metal (eutectic Ga-In alloy) microelectrode, which is used for junction formation, with a convenient photocurable polymeric scaffold enables untethering of the electrode and direct writing of arbitrary arrays of high-yielding molecular junctions under ambient conditions in a maskless fashion. The formed junctions function in quantitative yields and can afford tunneling currents with high reproducibility; they also function at low temperatures and under bent. The results reported here promise a massively parallel printing technology to construct integrated circuits based on molecular junctions with soft top contacts.
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Affiliation(s)
- Seo Eun Byeon
- Department of Chemistry, Korea University , Seoul 02841, Korea
| | - Miso Kim
- Department of Chemistry, Korea University , Seoul 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University , Seoul 02841, Korea
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41
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Towards Rectifying Performance at the Molecular Scale. Top Curr Chem (Cham) 2017; 375:85. [DOI: 10.1007/s41061-017-0170-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/22/2017] [Indexed: 01/09/2023]
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42
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Zhang Y, Qiu X, Gordiichuk P, Soni S, Krijger TL, Herrmann A, Chiechi RC. Mechanically and Electrically Robust Self-Assembled Monolayers for Large-Area Tunneling Junctions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:14920-14928. [PMID: 28729893 PMCID: PMC5512119 DOI: 10.1021/acs.jpcc.7b03853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/12/2017] [Indexed: 05/28/2023]
Abstract
This paper examines the relationship between mechanical deformation and the electronic properties of self-assembled monolayers (SAMs) of the oligothiophene 4-([2,2':5',2″:5″,2‴-quaterthiophen]-5-yl)butane-1-thiol (T4C4) in tunneling junctions using conductive probe atomic force microscopy (CP-AFM) and eutectic Ga-In (EGaIn). We compared shifts in conductivity, transition voltages of T4C4 with increasing AFM tip loading force to alkanethiolates. While these shifts result from an increasing tilt angle from penetration of the SAM by the AFM tip for the latter, we ascribe them to distortions of the π system present in T4C4, which is more mechanically robust than alkanethiolates of comparable length; SAMs comprising T4C4 shows about five times higher Young's modulus than alkanethiolates. Density functional theory calculations confirm that mechanical deformations shift the barrier height due to changes in the frontier orbitals caused by small rearrangements to the conformation of the quaterthiophene moiety. The mechanical robustness of T4C4 manifests as an increased tolerance to high bias in large-area EGaIn junctions suggesting that electrostatic pressure plays a significant role in the shorting of molecular junctions at high bias.
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Affiliation(s)
- Yanxi Zhang
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Xinkai Qiu
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Pavlo Gordiichuk
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Saurabh Soni
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Theodorus L. Krijger
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andreas Herrmann
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ryan C. Chiechi
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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43
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Molecular Diode Studies Based on a Highly Sensitive Molecular Measurement Technique. SENSORS 2017; 17:s17050956. [PMID: 28445393 PMCID: PMC5461080 DOI: 10.3390/s17050956] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/21/2017] [Accepted: 04/22/2017] [Indexed: 01/11/2023]
Abstract
In 1974, molecular electronics pioneers Mark Ratner and Arieh Aviram predicted that a single molecule could act as a diode, in which electronic current can be rectified. The electronic rectification property of the diode is one of basic functions of electronic components and since then, the molecular diode has been investigated as a first single-molecule device that would have a practical application. In this review, we first describe the experimental fabrication and electronic characterization techniques of molecular diodes consisting of a small number of molecules or a single molecule. Then, two main mechanisms of the rectification property of the molecular diode are discussed. Finally, representative results for the molecular diode are reviewed and a brief outlook on crucial issues that need to be addressed in future research is discussed.
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44
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Qiu L, Zhang Y, Krijger TL, Qiu X, Hof PV, Hummelen JC, Chiechi RC. Rectification of current responds to incorporation of fullerenes into mixed-monolayers of alkanethiolates in tunneling junctions. Chem Sci 2017; 8:2365-2372. [PMID: 28451341 PMCID: PMC5365006 DOI: 10.1039/c6sc04799h] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/18/2016] [Indexed: 12/19/2022] Open
Abstract
This paper describes the rectification of current through molecular junctions comprising self-assembled monolayers of decanethiolate through the incorporation of C60 fullerene moieties bearing undecanethiol groups in junctions using eutectic Ga-In (EGaIn) and Au conducting probe AFM (CP-AFM) top-contacts. The degree of rectification increases with increasing exposure of the decanethiolate monolayers to the fullerene moieties, going through a maximum after 24 h. We ascribe this observation to the resulting mixed-monolayer achieving an optimal packing density of fullerene cages sitting above the alkane monolayer. Thus, the degree of rectification is controlled by the amount of fullerene present in the mixed-monolayer. The voltage dependence of R varies with the composition of the top-contact and the force applied to the junction and the energy of the lowest unoccupied π-state determined from photoelectron spectroscopy is consistent with the direction of rectification. The maximum value of rectification R = |J(+)/J(-)| = 940 at ±1 V or 617 at ±0.95 V is in agreement with previous studies on pure monolayers relating the degree of rectification to the volume of the head-group on which the frontier orbitals are localized.
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Affiliation(s)
- Li Qiu
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Yanxi Zhang
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Theodorus L Krijger
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Xinkai Qiu
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Patrick Van't Hof
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Jan C Hummelen
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
| | - Ryan C Chiechi
- Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
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45
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Lamport ZA, Broadnax AD, Harrison D, Barth KJ, Mendenhall L, Hamilton CT, Guthold M, Thonhauser T, Welker ME, Jurchescu OD. Fluorinated benzalkylsilane molecular rectifiers. Sci Rep 2016; 6:38092. [PMID: 27897250 PMCID: PMC5126687 DOI: 10.1038/srep38092] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/03/2016] [Indexed: 11/26/2022] Open
Abstract
We report on the synthesis and electrical properties of nine new alkylated silane self-assembled monolayers (SAMs) – (EtO)3Si(CH2)nN = CHPhX where n = 3 or 11 and X = 4-CF3, 3,5-CF3, 3-F-4-CF3, 4-F, or 2,3,4,5,6-F, and explore their rectification behavior in relation to their molecular structure. The electrical properties of the films were examined in a metal/insulator/metal configuration, with a highly-doped silicon bottom contact and a eutectic gallium-indium liquid metal (EGaIn) top contact. The junctions exhibit high yields (>90%), a remarkable resistance to bias stress, and current rectification ratios (R) between 20 and 200 depending on the structure, degree of order, and internal dipole of each molecule. We found that the rectification ratio correlates positively with the strength of the molecular dipole moment and it is reduced with increasing molecular length.
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Affiliation(s)
- Zachary A Lamport
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA
| | - Angela D Broadnax
- Department of Chemistry, Wake Forest University, Winston Salem, NC 27109, USA
| | - David Harrison
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA
| | - Katrina J Barth
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA
| | - Lee Mendenhall
- Department of Chemistry, Wake Forest University, Winston Salem, NC 27109, USA
| | - Clayton T Hamilton
- Department of Chemistry, Wake Forest University, Winston Salem, NC 27109, USA
| | - Martin Guthold
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA
| | - Timo Thonhauser
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mark E Welker
- Department of Chemistry, Wake Forest University, Winston Salem, NC 27109, USA
| | - Oana D Jurchescu
- Department of Physics, Wake Forest University, Winston Salem, NC 27109, USA
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46
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Thompson D, Nijhuis CA. Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers. Acc Chem Res 2016; 49:2061-2069. [PMID: 27598413 DOI: 10.1021/acs.accounts.6b00256] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This Account describes a body of research in atomic level design, synthesis, physicochemical characterization, and macroscopic electrical testing of molecular devices made from ferrocene-functionalized alkanethiol molecules, which are molecular diodes, with the aim to identify, and resolve, the failure modes that cause leakage currents. The mismatch in size between the ferrocene headgroup and alkane rod makes waxlike highly dynamic self-assembled monolayers (SAMs) on coinage metals that show remarkable atomic-scale sensitivity in their electrical properties. Our results make clear that molecular tunnel junction devices provide an excellent testbed to probe the electronic and supramolecular structures of SAMs on inorganic substrates. Contacting these SAMs to a eutectic "EGaIn" alloy top-electrode, we designed highly stable long-lived molecular switches of the form electrode-SAM-electrode with robust rectification ratios of up to 3 orders of magnitude. The graphic that accompanies this conspectus displays a computed SAM packing structure, illustrating the lollipop shape of the molecules that gives dynamic SAM supramolecular structures and also the molecule-electrode van der Waals (vdW) contacts that must be controlled to form good SAM-based devices. In this Account, we first trace the evolution of SAM-based electronic devices and rationalize their operation using energy level diagrams. We describe the measurement of device properties using near edge X-ray absorption fine structure spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy complemented by molecular dynamics and electronic structure calculations together with large numbers of electrical measurements. We discuss how data obtained from these combined experimental/simulation codesign studies demonstrate control over the supramolecular and electronic structure of the devices, tuning odd-even effects to optimize inherent packing tendencies of the molecules in order to minimize leakage currents in the junctions. It is now possible, but still very costly to create atomically smooth electrodes and we discuss progress toward masking electrode imperfections using cooperative molecule-electrode contacts that are only accessible by dynamic SAM structures. Finally, the unique ability of SAM devices to achieve simultaneously high and atom-sensitive electrical switching is summarized and discussed. While putting these structures to work as real world electronic devices remains very challenging, we speculate on the scientific and technological advances that are required to further improve electronic and supramolecular structure, toward the creation of high yields of long-lived molecular devices with (very) large, reproducible rectification ratios.
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Affiliation(s)
- Damien Thompson
- Department
of Physics, Bernal Institute, University of Limerick, Limerick V94 T9PX, Ireland
| | - Christian A. Nijhuis
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
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47
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Kumar S, van Herpt J, Gengler RYN, Feringa BL, Rudolf P, Chiechi RC. Mixed Monolayers of Spiropyrans Maximize Tunneling Conductance Switching by Photoisomerization at the Molecule-Electrode Interface in EGaIn Junctions. J Am Chem Soc 2016; 138:12519-26. [PMID: 27602432 PMCID: PMC5053170 DOI: 10.1021/jacs.6b06806] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Indexed: 01/19/2023]
Abstract
This paper describes the photoinduced switching of conductance in tunneling junctions comprising self-assembled monolayers of a spiropyran moiety using eutectic Ga-In top contacts. Despite separation of the spiropyran unit from the electrode by a long alkyl ester chain, we observe an increase in the current density J of a factor of 35 at 1 V when the closed form is irradiated with UV light to induce the ring-opening reaction, one of the highest switching ratios reported for junctions incorporating self-assembled monolayers. The magnitude of switching of hexanethiol mixed monolayers was higher than that of pure spiropyran monolayers. The first switching event recovers 100% of the initial value of J and in the mixed-monolayers subsequent dampening is not the result of degradation of the monolayer. The observation of increased conductivity is supported by zero-bias DFT calculations showing a change in the localization of the density of states near the Fermi level as well as by simulated transmission spectra revealing positive resonances that broaden and shift toward the Fermi level in the open form.
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Affiliation(s)
- Sumit Kumar
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Jochem
T. van Herpt
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Régis Y. N. Gengler
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ben L. Feringa
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Petra Rudolf
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ryan C. Chiechi
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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48
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An Y, Zhang M, Wu D, Fu Z, Wang T, Jiao Z, Wang K. The magnetism and spin-dependent electronic transport properties of boron nitride atomic chains. J Chem Phys 2016; 145:044301. [DOI: 10.1063/1.4958626] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yipeng An
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
| | - Mengjun Zhang
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
| | - Dapeng Wu
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, China
| | - Zhaoming Fu
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Tianxing Wang
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
| | - Zhaoyong Jiao
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
| | - Kun Wang
- Department of Physics and Astronomy and NanoSEC, University of Georgia, Athens, Georgia 30602, USA
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49
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Yuan L, Franco C, Crivillers N, Mas-Torrent M, Cao L, Sangeeth CSS, Rovira C, Veciana J, Nijhuis CA. Chemical control over the energy-level alignment in a two-terminal junction. Nat Commun 2016; 7:12066. [PMID: 27456200 PMCID: PMC4963472 DOI: 10.1038/ncomms12066] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 05/25/2016] [Indexed: 01/20/2023] Open
Abstract
The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.
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Affiliation(s)
- Li Yuan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Carlos Franco
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain
| | - Núria Crivillers
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain
| | - Marta Mas-Torrent
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain
| | - Liang Cao
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - C S Suchand Sangeeth
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Concepció Rovira
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain
| | - Jaume Veciana
- Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.,Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, Singapore 117574, Singapore
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50
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Kong GD, Kim M, Cho SJ, Yoon HJ. Gradients of Rectification: Tuning Molecular Electronic Devices by the Controlled Use of Different-Sized Diluents in Heterogeneous Self-Assembled Monolayers. Angew Chem Int Ed Engl 2016; 55:10307-11. [DOI: 10.1002/anie.201604748] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/24/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Gyu Don Kong
- Department of Chemistry; Korea University; Seoul 136-701 Korea
| | - Miso Kim
- Department of Chemistry; Korea University; Seoul 136-701 Korea
| | - Soo Jin Cho
- Department of Chemistry; Korea University; Seoul 136-701 Korea
| | - Hyo Jae Yoon
- Department of Chemistry; Korea University; Seoul 136-701 Korea
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