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Wang Y, Han B, Mayor M, Samorì P. Opto-Electrochemical Synaptic Memory in Supramolecularly Engineered Janus 2D MoS 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2307359. [PMID: 37903551 DOI: 10.1002/adma.202307359] [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: 07/24/2023] [Revised: 10/25/2023] [Indexed: 11/01/2023]
Abstract
Artificial synapses combining multiple yet independent signal processing strategies in a single device are key enabler to achieve high-density of integration, energy efficiency, and fast data manipulation in brain-like computing. By taming functional complexity, the use of hybrids comprising multiple materials as active components in synaptic devices represents a powerful route to encode both short-term potentiation (STP) and long-term potentiation (LTP) in synaptic circuitries. To meet such a grand challenge, herein a novel Janus 2D material is developed by dressing asymmetrically the two surfaces of 2D molybdenum disulfide (MoS2 ) with an electrochemically-switchable ferrocene (Fc)/ ferrocenium (Fc+ ) redox couple and an optically-responsive photochromic azobenzene (Azo). Upon varying the magnitude of the electrochemical stimulus, it is possible to steer the transition between STP and LTP, thereby either triggering electrochemical doping of Fc/Fc+ pair on MoS2 or controlling an adsorption/desorption process of such redox species on MoS2 . In addition, a lower magnitude LTP is recorded by activating the photoisomerization of azobenzene chemisorbed molecules and therefore modulating the dipole-induced doping of the 2D semiconductor. Significantly, the interplay of electrochemical and optical stimuli makes it possible to construct artificial synapses where LTP can be boosted to 4-bit (16 memory states) while simultaneously functioning as STP.
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Affiliation(s)
- Ye Wang
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 Alleé Gaspard Monge, Strasbourg, F-67000, France
| | - Bin Han
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 Alleé Gaspard Monge, Strasbourg, F-67000, France
| | - Marcel Mayor
- Department of Chemistry, University of Basel, St. Johannsring 19, Basel, 4056, Switzerland
- Karlsruhe Institute of Technology KIT, Institute for Nanotechnology, P.O. Box 3640, 76021, Karlsruhe, Germany
| | - Paolo Samorì
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 Alleé Gaspard Monge, Strasbourg, F-67000, France
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2
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Yu SH, Hassan SZ, So C, Kang M, Chung DS. Molecular-Switch-Embedded Solution-Processed Semiconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2203401. [PMID: 35929102 DOI: 10.1002/adma.202203401] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Recent improvements in the performance of solution-processed semiconductor materials and optoelectronic devices have shifted research interest to the diversification/advancement of their functionality. Embedding a molecular switch capable of transition between two or more metastable isomers by light stimuli is one of the most straightforward and widely accepted methods to potentially realize the multifunctionality of optoelectronic devices. A molecular switch embedded in a semiconductor can effectively control various parameters such as trap-level, dielectric constant, electrical resistance, charge mobility, and charge polarity, which can be utilized in photoprogrammable devices including transistors, memory, and diodes. This review classifies the mechanism of each optoelectronic transition driven by molecular switches regardless of the type of semiconductor material or molecular switch or device. In addition, the basic characteristics of molecular switches and the persisting technical/scientific issues corresponding to each mechanism are discussed to help researchers. Finally, interesting yet infrequently reported applications of molecular switches and their mechanisms are also described.
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Affiliation(s)
- Seong Hoon Yu
- Department of Chemical Engineering, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Syed Zahid Hassan
- Department of Chemical Engineering, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Chan So
- Department of Chemical Engineering, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Mingyun Kang
- Department of Chemical Engineering, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Dae Sung Chung
- Department of Chemical Engineering, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
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3
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Hörmann L, Jeindl A, Hofmann OT. From a bistable adsorbate to a switchable interface: tetrachloropyrazine on Pt(111). NANOSCALE 2022; 14:5154-5162. [PMID: 35302562 PMCID: PMC8972298 DOI: 10.1039/d1nr07763e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Virtually all organic (opto)electronic devices rely on organic/inorganic interfaces with specific properties. These properties are, in turn, inextricably linked to the interface structure. Therefore, a change in structure can introduce a shift in function. If this change is reversible, it would allow constructing a switchable interface. We accomplish this with tetrachloropyrazine on Pt(111), which exhibits a double-well potential with a chemisorbed and a physisorbed minimum. These minima have significantly different adsorption geometries allowing the formation of switchable interface structures. Importantly, these structures facilitate different work function changes and coherent fractions (as would be obtained from X-ray standing wave measurements), which are ideal properties to read out the interface state. We perform surface structure search using a modified version of the SAMPLE approach and account for thermodynamic conditions using ab initio thermodynamics. This allows investigating millions of commensurate as well as higher-order commensurate interface structures. We identify three different classes of structures exhibiting different work function changes and coherent fractions. Using temperature and pressure as handles, we demonstrate the possibility of reversible switching between those different classes, creating a dynamic interface for potential applications in organic electronics.
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Affiliation(s)
- Lukas Hörmann
- Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Andreas Jeindl
- Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Oliver T Hofmann
- Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
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4
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Zhao Y, Gobbi M, Hueso LE, Samorì P. Molecular Approach to Engineer Two-Dimensional Devices for CMOS and beyond-CMOS Applications. Chem Rev 2021; 122:50-131. [PMID: 34816723 DOI: 10.1021/acs.chemrev.1c00497] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two-dimensional materials (2DMs) have attracted tremendous research interest over the last two decades. Their unique optical, electronic, thermal, and mechanical properties make 2DMs key building blocks for the fabrication of novel complementary metal-oxide-semiconductor (CMOS) and beyond-CMOS devices. Major advances in device functionality and performance have been made by the covalent or noncovalent functionalization of 2DMs with molecules: while the molecular coating of metal electrodes and dielectrics allows for more efficient charge injection and transport through the 2DMs, the combination of dynamic molecular systems, capable to respond to external stimuli, with 2DMs makes it possible to generate hybrid systems possessing new properties by realizing stimuli-responsive functional devices and thereby enabling functional diversification in More-than-Moore technologies. In this review, we first introduce emerging 2DMs, various classes of (macro)molecules, and molecular switches and discuss their relevant properties. We then turn to 2DM/molecule hybrid systems and the various physical and chemical strategies used to synthesize them. Next, we discuss the use of molecules and assemblies thereof to boost the performance of 2D transistors for CMOS applications and to impart diverse functionalities in beyond-CMOS devices. Finally, we present the challenges, opportunities, and long-term perspectives in this technologically promising field.
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Affiliation(s)
- Yuda Zhao
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France.,School of Micro-Nano Electronics, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, 310027 Hangzhou, People's Republic of China
| | - Marco Gobbi
- Centro de Fisica de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, E-20018 Donostia-San Sebastián, Spain.,CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Luis E Hueso
- CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Paolo Samorì
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France
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5
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Sumrra SH, Arshad Z, Zafar W, Mahmood K, Ashfaq M, Hassan AU, Mughal EU, Irfan A, Imran M. Metal incorporated aminothiazole-derived compounds: synthesis, density function theory analysis, in vitro antibacterial and antioxidant evaluation. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210910. [PMID: 34631124 PMCID: PMC8479342 DOI: 10.1098/rsos.210910] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/01/2021] [Indexed: 05/23/2023]
Abstract
The present study advocates the combined experimental and computational study of metal-based aminothiazole-derived Schiff base ligands. The structure and electronic properties of ligands have been experimentally studied by spectroscopic methods (UV-Vis, FT-IR, 1H-NMR and 13C-NMR), mass spectrometry, elemental analysis and theoretically by density function theory (DFT). Computational calculations employing the B3LYP/6-31 + G(d,p) functional of DFT were executed to explore the optimized geometrical structures of ligands along with geometric parameters, molecular electrostatic potential (MEP) surfaces and frontier molecular orbital (FMO) energies. Global reactivity parameters estimated from FMO energy gaps signified the bioactive nature of ligands. The synthesized ligands were used for chelation with 3d-transition metals [VO(IV), Cr(III), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] in 1 : 2 (metal : ligand) molar ratio. The spectral and magnetic results confirmed the formation of octahedral geometry around all the divalent and trivalent metal centres, whereas the tetravalent vanadyl centres were confirmed to have square-pyramidal geometry. All the as-synthesized compounds were investigated for in vitro antibacterial potential against two Gram-negative (Salmonella typhimurium and Escherichia coli) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria. Antibacterial assay results displayed pronounced activity, and their activity is comparable to that of a standard drug (streptomycin). The antioxidant potential of these compounds was assessed by employing diphenyl picryl hydrazide radical scavenging activity. The results displayed that all the metal chelates have exhibited more bioactivity in contrast with free ligands. The chelation was the main reason for their enhanced bioactivity. These results indicated that the thiazole metal-based compounds could be exploited as antioxidant and antimicrobial candidates.
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Affiliation(s)
| | - Zunaira Arshad
- Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | - Wardha Zafar
- Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | - Khalid Mahmood
- Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Muhammad Ashfaq
- Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | - Abrar Ul Hassan
- Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | | | - Ahmad Irfan
- Research Center for Advanced Materials Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
- Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
| | - Muhammad Imran
- Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
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6
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Diez Cabanes V, Van Dyck C, Osella S, Cornil D, Cornil J. Challenges for Incorporating Optical Switchability in Organic-Based Electronic Devices. ACS APPLIED MATERIALS & INTERFACES 2021; 13:27737-27748. [PMID: 34105343 DOI: 10.1021/acsami.1c05489] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Transistors operate by controlling the current flowing from a source to a drain electrode via a third electrode (gate), thus giving access to a binary treatment (ON/OFF or 0/1) of the signal currently exploited in microelectronics. Introducing a second independent lever to modulate the current would allow for more complex logic functions amenable to a single electronic component and hence to new opportunities for advanced electrical signal processing. One avenue is to add this second dimension with light by incorporating photochromic molecules in current organic-based electronic devices. In this Spotlight, we describe different concepts that have been implemented in organic thin films and in molecular junctions as well as some pitfalls that have been highlighted thanks to theoretical modeling.
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Affiliation(s)
- Valentin Diez Cabanes
- Laboratoire de Physique et Chimie Théoriques, Université de Lorraine & CNRS, 54000 Nancy, France
| | - Colin Van Dyck
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
| | - Silvio Osella
- Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warszawa, Poland
| | - David Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
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7
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Nguyen DT, Freitag M, Gutheil C, Sotthewes K, Tyler BJ, Böckmann M, Das M, Schlüter F, Doltsinis NL, Arlinghaus HF, Ravoo BJ, Glorius F. Ein auf Arylazopyrazol basierendes N‐heterocyclisches Carben als Photoschalter auf Goldoberflächen: Lichtschaltbare Benetzbarkeit, Austrittsarbeit und Leitwert. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003523] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- D. Thao Nguyen
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
- Center for Soft Nanoscience (SoN) Westfälische Wilhelms-Universität Münster Busso-Peus-Straße 10 48149 Münster Deutschland
| | - Matthias Freitag
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
| | - Christian Gutheil
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials MESA+ Institute for Nanotechnology University of Twente P.O. Box 217 7500 AE Enschede Niederlande
| | - Bonnie J. Tyler
- Physikalisches Institut Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Straße 10 48149 Münster Deutschland
| | - Marcus Böckmann
- Institute for Solid State Theory and Center for Multiscale Theory & Computation Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Straße 10 48149 Münster Deutschland
| | - Mowpriya Das
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
| | - Friederike Schlüter
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
- Center for Soft Nanoscience (SoN) Westfälische Wilhelms-Universität Münster Busso-Peus-Straße 10 48149 Münster Deutschland
| | - Nikos L. Doltsinis
- Institute for Solid State Theory and Center for Multiscale Theory & Computation Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Straße 10 48149 Münster Deutschland
| | - Heinrich F. Arlinghaus
- Physikalisches Institut Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Straße 10 48149 Münster Deutschland
| | - Bart Jan Ravoo
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
- Center for Soft Nanoscience (SoN) Westfälische Wilhelms-Universität Münster Busso-Peus-Straße 10 48149 Münster Deutschland
| | - Frank Glorius
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Deutschland
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8
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Nguyen DT, Freitag M, Gutheil C, Sotthewes K, Tyler BJ, Böckmann M, Das M, Schlüter F, Doltsinis NL, Arlinghaus HF, Ravoo BJ, Glorius F. An Arylazopyrazole-Based N-Heterocyclic Carbene as a Photoswitch on Gold Surfaces: Light-Switchable Wettability, Work Function, and Conductance. Angew Chem Int Ed Engl 2020; 59:13651-13656. [PMID: 32271973 DOI: 10.1002/anie.202003523] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 04/08/2020] [Indexed: 12/13/2022]
Abstract
A novel photoresponsive and fully conjugated N-heterocyclic carbene (NHC) has been synthesized that combines the excellent photophysical properties of arylazopyrazoles (AAPs) with an NHC that acts as a robust surface anchor (AAP-BIMe). The formation of self-assembled monolayers (SAMs) on gold was proven by ToF-SIMS and XPS, and the organic film displayed a very high stability at elevated temperatures. This stability was also reflected in a high desorption energy, which was determined by temperature-programmed SIMS measurements. E-/Z-AAP-BIMe@Au photoisomerization resulted in reversible alterations of the surface energy (i.e. wettability), the surface potential (i.e. work function), and the conductance (i.e. resistance). The effects could be explained by the difference in the dipole moment of the isomers. Furthermore, sequential application of a dummy ligand by microcontact printing and subsequent backfilling with AAP-BIMe allowed its patterning on gold. To the best of our knowledge, this is the first example of a photoswitchable NHC on a gold surface. These properties of AAP-BIMe@Au illustrate its suitability as a molecular switch for electronic devices.
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Affiliation(s)
- D Thao Nguyen
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.,Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Strasse 10, 48149, Münster, Germany
| | - Matthias Freitag
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - Christian Gutheil
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands
| | - Bonnie J Tyler
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149, Münster, Germany
| | - Marcus Böckmann
- Institute for Solid State Theory and Center for Multiscale Theory & Computation, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149, Münster, Germany
| | - Mowpriya Das
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - Friederike Schlüter
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.,Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Strasse 10, 48149, Münster, Germany
| | - Nikos L Doltsinis
- Institute for Solid State Theory and Center for Multiscale Theory & Computation, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149, Münster, Germany
| | - Heinrich F Arlinghaus
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149, Münster, Germany
| | - Bart Jan Ravoo
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany.,Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Busso-Peus-Strasse 10, 48149, Münster, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
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9
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Hou J, Ke C, Chen J, Sun B, Xia Y, Li X, Chen T, Wu Y, Wu Z, Kang J. Reduced Turn-On Voltage and Boosted Mobility in Monolayer WS 2 Transistors by Mild Ar + Plasma Treatment. ACS APPLIED MATERIALS & INTERFACES 2020; 12:19635-19642. [PMID: 32255332 DOI: 10.1021/acsami.0c00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Monolayer two-dimensional transition-metal dichalcogenides, such as tungsten disulfide (WS2), are regarded as promising candidates for optoelectronic and electronic applications. Although theoretical calculations have predicted outstanding electronic properties of WS2, the performance of WS2-based electronic devices is still limited by the relatively high Schottky barrier and low carrier mobility. In this work, low-energy argon (Ar+) plasma treatment was used as a nondestructive preconditioning technique to tailor the electrical properties of the WS2 monolayer grown by chemical vapor deposition. Photoluminescence and Raman spectroscopy were used to monitor the modified optical properties of WS2 with increasing plasma treatment time. An improved electrical conductivity was observed after a short-time plasma treatment. The physical mechanism was further revealed by a comparative study between top-electrode and bottom-electrode devices and simulation based on the density functional theory. It is concluded that mild Ar+ plasma treatment can effectively lower the Schottky barrier height and the effective mass of carriers, which reduces the turn-on voltage and enhances the mobility, respectively. However, if the processing time is too long, the WS2 lattice structure will be destroyed. This work has provided an effective method for manipulating the Schottky barrier and mobility of monolayer WS2 transistors and paves the way for developing high-performance electronic devices based on 2D semiconductors.
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Affiliation(s)
- Junfeng Hou
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Congming Ke
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Jiajun Chen
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Baofan Sun
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Yuanzheng Xia
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Xu Li
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Ting Chen
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Yaping Wu
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Zhiming Wu
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
| | - Junyong Kang
- Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Jiujiang Research Institute, Xiamen University, Xiamen 361005, P. R. China
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10
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Schuster S, Füser M, Asyuda A, Cyganik P, Terfort A, Zharnikov M. Photoisomerization of azobenzene-substituted alkanethiolates on Au(111) substrates in the context of work function variation: the effect of structure and packing density. Phys Chem Chem Phys 2019; 21:9098-9105. [PMID: 31017144 DOI: 10.1039/c9cp00255c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Photoisomerization of a series of custom-designed, azobenzene-substituted alkanethiolate (AT) self-assembled monolayers (SAMs) on Au(111) substrates was studied in the context of work function variation, using Kelvin probe measurements as a transduction technique. These SAMs featured variable packing density (by ∼14%; due to the odd-even effects) and, as an option, were additionally decorated with the electron donating/withdrawing -CH3 and -CF3 tail group, respectively, which induce additional dipole moments. The efficiency of photoisomerization and the respective extent of work function variation (ΔΦ) were found to be quite low and independent of the packing density in the SAMs, within the given odd-even packing density variation. They could only be increased, up to ca. 40 meV for ΔΦ, by mixing the azobenzene-substituted ATs with shorter "matrix" molecules, which were introduced for a partial release of the sterical constraints. The ΔΦ values for the SAMs decorated with the -CH3 and -CF3 tail groups were found to be lower than those for the monolayers without such a decoration, which correlated well with the theoretical estimates for the change of the dipole moment of the relevant molecules upon the photoisomerization.
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Affiliation(s)
- Swen Schuster
- Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
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11
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Bertolazzi S, Gobbi M, Zhao Y, Backes C, Samorì P. Molecular chemistry approaches for tuning the properties of two-dimensional transition metal dichalcogenides. Chem Soc Rev 2018; 47:6845-6888. [PMID: 30043037 DOI: 10.1039/c8cs00169c] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Two-dimensional (2D) semiconductors, such as ultrathin layers of transition metal dichalcogenides (TMDs), offer a unique combination of electronic, optical and mechanical properties, and hold potential to enable a host of new device applications spanning from flexible/wearable (opto)electronics to energy-harvesting and sensing technologies. A critical requirement for developing practical and reliable electronic devices based on semiconducting TMDs consists in achieving a full control over their charge-carrier polarity and doping. Inconveniently, such a challenging task cannot be accomplished by means of well-established doping techniques (e.g. ion implantation and diffusion), which unavoidably damage the 2D crystals resulting in degraded device performances. Nowadays, a number of alternatives are being investigated, including various (supra)molecular chemistry approaches relying on the combination of 2D semiconductors with electroactive donor/acceptor molecules. As yet, a large variety of molecular systems have been utilized for functionalizing 2D TMDs via both covalent and non-covalent interactions. Such research endeavours enabled not only the tuning of the charge-carrier doping but also the engineering of the optical, electronic, magnetic, thermal and sensing properties of semiconducting TMDs for specific device applications. Here, we will review the most enlightening recent advancements in experimental (supra)molecular chemistry methods for tailoring the properties of atomically-thin TMDs - in the form of substrate-supported or solution-dispersed nanosheets - and we will discuss the opportunities and the challenges towards the realization of novel hybrid materials and devices based on 2D semiconductors and molecular systems.
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Affiliation(s)
- Simone Bertolazzi
- Université de Strasbourg, CNRS, ISIS, 8 alleé Gaspard Monge, 67000 Strasbourg, France.
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12
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Senanayak SP, Sangwan VK, McMorrow JJ, Everaerts K, Chen Z, Facchetti A, Hersam MC, Marks TJ, Narayan KS. Self-Assembled Photochromic Molecular Dipoles for High-Performance Polymer Thin-Film Transistors. ACS APPLIED MATERIALS & INTERFACES 2018; 10:21492-21498. [PMID: 29847908 DOI: 10.1021/acsami.8b05401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The development of high-performance multifunctional polymer-based electronic circuits is a major step toward future flexible electronics. Here, we demonstrate a tunable approach to fabricate such devices based on rationally designed dielectric super-lattice structures with photochromic azobenzene molecules. These nanodielectrics possessing ionic, molecular, and atomic polarization are utilized in polymer thin-film transistors (TFTs) to realize high-performance electronics with a p-type field-effect mobility (μFET) exceeding 2 cm2 V-1 s-1. A crossover in the transport mechanism from electrostatic dipolar disorder to ionic-induced disorder is observed in the transistor characteristics over a range of temperatures. The facile supramolecular design allows the possibility to optically control the extent of molecular and ionic polarization in the ultrathin nanodielectric. Thus, we demonstrate a 3-fold increase in the capacitance from 0.1 to 0.34 μF/cm2, which results in a 200% increase in TFT channel current.
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Affiliation(s)
- Satyaprasad P Senanayak
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560064 , India
- Optoelectronics Group , Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | | | | | | | - Zhihua Chen
- Flexterra Inc. , 8025 Lamon Avenue , Skokie , Illinois 60077 , United States
| | - Antonio Facchetti
- Flexterra Inc. , 8025 Lamon Avenue , Skokie , Illinois 60077 , United States
| | | | | | - K S Narayan
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560064 , India
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13
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Rodriguez-Gonzalez S, Xie Z, Galangau O, Selvanathan P, Norel L, Van Dyck C, Costuas K, Frisbie CD, Rigaut S, Cornil J. HOMO Level Pinning in Molecular Junctions: Joint Theoretical and Experimental Evidence. J Phys Chem Lett 2018; 9:2394-2403. [PMID: 29660279 DOI: 10.1021/acs.jpclett.8b00575] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A central issue in molecular electronics in order to build functional devices is to assess whether changes in the electronic structure of isolated compounds by chemical derivatization are retained once the molecules are inserted into molecular junctions. Recent theoretical studies have suggested that this is not always the case due to the occurrence of pinning effects making the alignment of the transporting levels insensitive to the changes in the electronic structure of the isolated systems. We explore here this phenomenon by investigating at both the experimental and theoretical levels the I/ V characteristics of molecular junctions incorporating three different three-ring phenylene ethynylene derivatives designed to exhibit a significant variation of the HOMO level in the isolated state. At the theoretical level, our NEGF/DFT calculations performed on junctions including the three compounds show that, whereas the HOMO of the molecules varies by 0.61 eV in the isolated state, their alignment with respect to the Fermi level of the gold electrodes in the junction is very similar (within 0.1 eV). At the experimental level, the SAMs made of the three compounds have been contacted by a conducting AFM probe to measure their I/ V characteristics. The alignment of the HOMO with respect to the Fermi level of the gold electrodes has been deduced by fitting the I/ V curves, using a model based on a single-level description (Newns-Anderson model). The extracted values are found to be very similar for the three derivatives, in full consistency with the theoretical predictions, thus providing clear evidence for a HOMO level pinning effect.
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Affiliation(s)
- S Rodriguez-Gonzalez
- Laboratory for Chemistry of Novel Materials , University of Mons , B-7000 Mons , Belgium
| | - Z Xie
- Department of Chemical Engineering and Materials Science , and Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - O Galangau
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - P Selvanathan
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - L Norel
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - C Van Dyck
- National Institute for Nanotechnology (NINT) , University of Alberta , Edmonton , Alberta T6G 2M9 , Canada
| | - K Costuas
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - C D Frisbie
- Department of Chemical Engineering and Materials Science , and Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - S Rigaut
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - J Cornil
- Laboratory for Chemistry of Novel Materials , University of Mons , B-7000 Mons , Belgium
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14
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Diez-Cabanes V, Gonzalez SR, Osella S, Cornil D, Van Dyck C, Cornil J. Energy Level Alignment at Interfaces Between Au (111) and Thiolated Oligophenylenes of Increasing Chain Size: Theoretical Evidence of Pinning Effects. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201700020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
| | | | - Silvio Osella
- Centre of New Technologies; University of Warsaw; Warszawa 02-097 Poland
| | - David Cornil
- Laboratory for Chemistry of Novel Materials; University of Mons; Mons 7000 Belgium
| | - Colin Van Dyck
- National Institute for Nanotechnology; Edmonton AB T6G 2M9 Canada
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials; University of Mons; Mons 7000 Belgium
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15
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Bronsch W, Moldt T, Boie L, Gahl C, Weinelt M. Delocalized versus localized excitations in the photoisomerization of azobenzene-functionalized alkanethiolate SAMs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:484002. [PMID: 29022887 DOI: 10.1088/1361-648x/aa9309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembled monolayers of azobenzene-functionalized alkanethiolates form molecular ensembles with preferential orientation and significant excitonic coupling among the azobenzene chromophores. We have studied their optical switching with differential reflectance and two-photon-photoemission spectroscopy tuning the excitation wavelength through the excitonically broadened S2 absorption band. While the effective isomerization cross-section increases towards shorter wavelengths, the fraction of cis molecules in the photostationary state decreases. We attribute this observation to the absorption of the cis isomer in the SAM. The photoisomerization in the SAM thereby follows the behavior of non-interacting chromophores in solution, despite the formation of H-aggregates. Our study thus reveals that photoswitching occurs via localized excitations while strongly excitonically coupled, delocalized states do not contribute significantly.
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Affiliation(s)
- Wibke Bronsch
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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16
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Liu C, Zheng D, Hu W, Zhu Q, Tian Z, Zhao J, Zhu Y, Ma J. Tuning the collective switching behavior of azobenzene/Au hybrid materials: flexible versus rigid azobenzene backbones and Au(111) surfaces versus curved Au nanoparticles. NANOSCALE 2017; 9:16700-16710. [PMID: 29067386 DOI: 10.1039/c7nr03421k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The combination of photo-responsive azobenzene (AB) and biocompatible Au nanomaterials possesses potential applications in diverse fields such as biosensing and thermotherapy. To explore the influence of azobenzene moieties and Au substrates on the collective switching behavior, two different azobenzene derivatives (rigid biphenyl-controlled versus flexible alkoxyl chain-linked) and three different Au substrates (a planar Au(111) surface, curved Au102(SR)44 and Au25(SR)18 clusters) were chosen to form six Au@AB combinations. A reactive molecular dynamics (RMD) model considering both the torsion and inversion path was implemented to simulate the collective photo-induced cis-to-trans switching process of AB monolayers on Au substrates. The major driving force for isomerization is demonstrated to be the torsion of the C-N[double bond, length as m-dash]N-C dihedral angle, in addition to the minor contribution from an inversion pathway. The isomerization process can be divided into the preliminary conformation switching stage and the later relaxation stage, in which a gradual self-organization is observed for 40 ps. The Au substrate affects the packing structure of the AB monolayer, while the choice of different kinds of ABs tunes the intermolecular interaction in the monolayer. Flexible alkoxyl-linked F-AB may achieve much faster conversion on Au clusters than on the surface. For rigid biphenyl-based R-AB anchored on Au nanoparticles (AuNPs), a competitive torsion between the biphenyl and C-N[double bond, length as m-dash]N-C dihedral may delay the C-N[double bond, length as m-dash]N-C dihedral torsion and the following isomerization process. After the R-AB molecules were anchored on the Au(111) surface, the strong π-π stacking between biphenyl units accelerates the collective isomerization process. A curvature-dependent effect is observed for R-AB SAMs on different-sized substrates. The cooperation between functional AB monolayers and the Au substrate determines the collective switching behavior of Au@AB materials. These results are expected to guide rational designs of Au@AB hybrid materials for different uses.
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Affiliation(s)
- Chunyan Liu
- Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry & Chemical Engineering, Nanjing University, 22 Hankou Road, Nanjing, 210093, People's Republic of China.
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17
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Malyar IV, Titov E, Lomadze N, Saalfrank P, Santer S. Photoswitching of azobenzene-containing self-assembled monolayers as a tool for control over silicon surface electronic properties. J Chem Phys 2017; 146:104703. [DOI: 10.1063/1.4978225] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ivan V. Malyar
- Department of Nano- and Biomedical Technologies, Saratov State University, Astrakhanskaya 83, 410012 Saratov, Russia
| | - Evgenii Titov
- Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
- Theoretical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Nino Lomadze
- Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Peter Saalfrank
- Theoretical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Svetlana Santer
- Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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18
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Moldt T, Przyrembel D, Schulze M, Bronsch W, Boie L, Brete D, Gahl C, Klajn R, Tegeder P, Weinelt M. Differing Isomerization Kinetics of Azobenzene-Functionalized Self-Assembled Monolayers in Ambient Air and in Vacuum. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10795-10801. [PMID: 27681851 DOI: 10.1021/acs.langmuir.6b01690] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Azobenzenealkanethiols in self-assembled monolayers (SAMs) on Au(111) exhibit reversible trans-cis photoisomerization when diluted with alkanethiol spacers. Using these mixed SAMs, we show switching of the linear optical and second-harmonic response. The effective switching of these surface optical properties relies on a reasonably large cross section and a high photoisomerization yield as well as a long lifetime of the metastable cis isomer. We quantified the switching process by X-ray absorption spectroscopy. The cross sections for the trans-cis and cis-trans photoisomerization with 365 and 455 nm light, respectively, are 1 order of magnitude smaller than in solution. In vacuum, the 365 nm photostationary state comprises 50-74% of the molecules in the cis form, limited by their rapid thermal isomerization back to the trans state. In contrast, the 455 nm photostationary state contains nearly 100% trans-azobenzene. We determined time constants for the thermal cis-trans isomerization of only a few minutes in vacuum and in a dry nitrogen atmosphere but of more than 1 day in ambient air. Our results suggest that adventitious water adsorbed on the surface of the SAM stabilizes the polar cis configuration of azobenzene under ambient conditions. The back reaction rate constants differing by 2 orders of magnitude underline the huge influence of the environment and, accordingly, its importance when comparing various experiments.
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Affiliation(s)
- Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Daniel Przyrembel
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Michael Schulze
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany
| | - Wibke Bronsch
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Larissa Boie
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Daniel Brete
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Cornelius Gahl
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Rafal Klajn
- Department of Organic Chemistry, Weizmann Institute of Science , 76100 Rehovot, Israel
| | - Petra Tegeder
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
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19
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Barachevsky VA. Electrical properties of photochromic organic systems (review). HIGH ENERGY CHEMISTRY 2016. [DOI: 10.1134/s0018143916050040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Fu LN, Leng B, Li YS, Gao XK. Photoresponsive organic field-effect transistors involving photochromic molecules. CHINESE CHEM LETT 2016. [DOI: 10.1016/j.cclet.2016.06.045] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Margapoti E, Li J, Ceylan Ö, Seifert M, Nisic F, Anh TL, Meggendorfer F, Dragonetti C, Palma CA, Barth JV, Finley JJ. A 2D semiconductor-self-assembled monolayer photoswitchable diode. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:1426-1431. [PMID: 25641369 DOI: 10.1002/adma.201405110] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/15/2014] [Indexed: 06/04/2023]
Abstract
A switchable diode in a 2D semiconductor-molecular junction heterostructure is reported. MoS2 is exfoliated on top of a monolayer of azobenzene-substituted thiols on gold. Photoisomerization of the azobenzenes results in switching between a rectifier with rectifying ratios of 10(4) and a conductive state, as revealed by conducting atomic force microscopy.
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Affiliation(s)
- Emanuela Margapoti
- Walter Schottky Institute, Physik-Department and NIM, Technische Universität München, Am Coulombwall 4, Garching, D-85748, Germany
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22
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Li P, Di Stasio F, Eda G, Fenwick O, McDonnell SO, Anderson HL, Chhowalla M, Cacialli F. Luminescent Properties of a Water-Soluble Conjugated Polymer Incorporating Graphene-Oxide Quantum Dots. Chemphyschem 2015; 16:1258-62. [DOI: 10.1002/cphc.201402744] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Indexed: 11/06/2022]
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23
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Moldt T, Brete D, Przyrembel D, Das S, Goldman JR, Kundu PK, Gahl C, Klajn R, Weinelt M. Tailoring the properties of surface-immobilized azobenzenes by monolayer dilution and surface curvature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1048-57. [PMID: 25544061 DOI: 10.1021/la504291n] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Photoswitching in densely packed azobenzene self-assembled monolayers (SAMs) is strongly affected by steric constraints and excitonic coupling between neighboring chromophores. Therefore, control of the chromophore density is essential for enhancing and manipulating the photoisomerization yield. We systematically compare two methods to achieve this goal: First, we assemble monocomponent azobenzene-alkanethiolate SAMs on gold nanoparticles of varying size. Second, we form mixed SAMs of azobenzene-alkanethiolates and "dummy" alkanethiolates on planar substrates. Both methods lead to a gradual decrease of the chromophore density and enable efficient photoswitching with low-power light sources. X-ray spectroscopy reveals that coadsorption from solution yields mixtures with tunable composition. The orientation of the chromophores with respect to the surface normal changes from a tilted to an upright position with increasing azobenzene density. For both systems, optical spectroscopy reveals a pronounced excitonic shift that increases with the chromophore density. In spite of exciting the optical transition of the monomer, the main spectral change in mixed SAMs occurs in the excitonic band. In addition, the photoisomerization yield decreases only slightly by increasing the azobenzene-alkanethiolate density, and we observed photoswitching even with minor dilutions. Unlike in solution, azobenzene in the planar SAM can be switched back almost completely by optical excitation from the cis to the original trans state within a short time scale. These observations indicate cooperativity in the photoswitching process of mixed SAMs.
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Affiliation(s)
- Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
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24
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Masillamani AM, Osella S, Liscio A, Fenwick O, Reinders F, Mayor M, Palermo V, Cornil J, Samorì P. Light-induced reversible modification of the work function of a new perfluorinated biphenyl azobenzene chemisorbed on Au (111). NANOSCALE 2014; 6:8969-8977. [PMID: 24968023 DOI: 10.1039/c4nr01880j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We describe the synthesis of a novel biphenyl azobenzene derivative exhibiting: (i) a protected thiol anchoring group in the α-position to readily form self-assembled monolayers (SAMs) on Au surfaces; and (ii) a terminal perfluorinated benzene ring in the ω-position to modify the surface properties. The design of this molecule ensured both an efficient in situ photoswitching between the trans and cis isomers when chemisorbed on Au(111), due to the presence of a biphenyl bridge between the thiol protected anchoring group and the azo dye, and a significant variation of the work function of the SAM in the two isomeric states, induced by the perfluorinated phenyl head group. By exploiting the light responsive nature of the chemisorbed molecules, it is possible to dynamically modify in situ the work function of the SAM-covered electrode, as demonstrated both experimentally and by quantum-chemical calculations, revealing changes in work function up to 220 meV. These findings are relevant for tuning the work function of metallic electrodes, and hence to dynamically modulate charge injection at metal-semiconductor interfaces for organic opto-electronic applications.
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25
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Orgiu E, Samorì P. 25th anniversary article: organic electronics marries photochromism: generation of multifunctional interfaces, materials, and devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:1827-1845. [PMID: 24554562 DOI: 10.1002/adma.201304695] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/13/2014] [Indexed: 06/03/2023]
Abstract
Organic semiconductors have garnered significant interest as key components for flexible, low-cost, and large-area electronics. Hitherto, both materials and processing thereof seems to head towards a mature technology which shall ultimately meet expectations and efforts built up over the past years. However, by its own organic electronics cannot compete or complement the silicon-based electronics in integrating multiple functions in a small area unless novel solutions are brought into play. Photochromic molecules are small organic molecules able to undergo reversible photochemical isomerization between (at least) two (meta)stable states which exhibit markedly different properties. They can be embedded as additional component in organic-based materials ready to be exploited in devices such as OLEDs, OFETs, and OLETs. The structurally controlled incorporation of photochromic molecules can be done at various interfaces of a device, including the electrode/semiconductor or dielectric/semiconductor interface, or even as a binary mixture in the active layer, in order to impart a light responsive nature to the device. This can be accomplished by modulating via a light stimulus fundamental physico-chemical properties such as charge injection and transport in the device.
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Affiliation(s)
- Emanuele Orgiu
- Nanochemistry Laboratory, ISIS & icFRC, Université de Strasbourg & CNRS, 8 allée Gaspard Monge, 67000, Strasbourg, France
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26
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Osella S, Cornil D, Cornil J. Work function modification of the (111) gold surface covered by long alkanethiol-based self-assembled monolayers. Phys Chem Chem Phys 2014; 16:2866-73. [DOI: 10.1039/c3cp54217c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Pipolo S, Benassi E, Corni S. Structural properties of azobenzene self-assembled monolayers by atomistic simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:10505-10512. [PMID: 23879669 DOI: 10.1021/la401645k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Azobenzene self-assembled monolayers (SAMs) are examples of optomechanical nanostructures capable of producing mechanical work through the well-known azobenzene photoisomerization process. Experimental studies have provided information on their structural properties, but an atomistic description of the SAMs in both the cis and trans forms is still lacking. In this work, a computational investigation of the SAM structures is conducted by classical molecular dynamics with a dedicated force. Experimental data on the SAM unit cell is used to set up SAM models of different molecular densities. The optimal structures are identified through the comparison with structural data from X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies. The resulting SAM atomistic models are validated by comparing simulated and experimental scanning tunneling microscopy images.
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Affiliation(s)
- Silvio Pipolo
- Center S3, CNR Institute of Nanoscience, Via Campi 213/A, 41121 Modena, Italy.
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28
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Liaros N, Couris S, Maggini L, De Leo F, Cattaruzza F, Aurisicchio C, Bonifazi D. NLO Response of Photoswitchable Azobenzene-Based Materials. Chemphyschem 2013; 14:2961-72. [DOI: 10.1002/cphc.201300420] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Indexed: 11/09/2022]
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29
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Gahl C, Brete D, Leyssner F, Koch M, McNellis ER, Mielke J, Carley R, Grill L, Reuter K, Tegeder P, Weinelt M. Coverage- and Temperature-Controlled Isomerization of an Imine Derivative on Au(111). J Am Chem Soc 2013; 135:4273-81. [DOI: 10.1021/ja309330e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Cornelius Gahl
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
| | - Daniel Brete
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
- Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin,
Germany
| | - Felix Leyssner
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
| | - Matthias Koch
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
| | - Erik R. McNellis
- Department of
Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg
10, 55128 Mainz, Germany
| | - Johannes Mielke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
| | - Robert Carley
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
- Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin,
Germany
| | - Leonhard Grill
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
| | - Karsten Reuter
- Lehrstuhl für Theoretische
Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Petra Tegeder
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195
Berlin, Germany
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30
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Crivillers N, Osella S, Van Dyck C, Lazzerini GM, Cornil D, Liscio A, Di Stasio F, Mian S, Fenwick O, Reinders F, Neuburger M, Treossi E, Mayor M, Palermo V, Cacialli F, Cornil J, Samorì P. Large work function shift of gold induced by a novel perfluorinated azobenzene-based self-assembled monolayer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:432-436. [PMID: 22851440 DOI: 10.1002/adma.201201737] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/20/2012] [Indexed: 05/28/2023]
Abstract
Tune it with light! Self-assembled monolayers on gold based on a chemisorbed novel azobenzene derivative with a perfluorinated terminal phenyl ring are prepared. The modified substrate shows a significant work function increase compared to the bare metal. The photo-conversion between trans and cis isomers chemisorbed on the surface shows great perspectives for being an accessible route to tune the gold properties by means of light.
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Affiliation(s)
- Núria Crivillers
- ISIS & icFRC, Université de Strasbourg & CNRS, 8 allée Gaspard Monge, 67000 Strasbourg, France
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31
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Van Dyck C, Geskin V, Kronemeijer AJ, de Leeuw DM, Cornil J. Impact of derivatization on electron transmission through dithienylethene-based photoswitches in molecular junctions. Phys Chem Chem Phys 2013; 15:4392-404. [DOI: 10.1039/c3cp44132f] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Brete D, Przyrembel D, Eickhoff C, Carley R, Freyer W, Reuter K, Gahl C, Weinelt M. Mixed self-assembled monolayers of azobenzene photoswitches with trifluoromethyl and cyano end groups. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:394015. [PMID: 22964547 DOI: 10.1088/0953-8984/24/39/394015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Mixed self-assembled monolayers (SAMs) of alkanethiolates carrying azobenzene chromophores with either a trifluoromethyl or a cyano substituent have been studied. High-resolution x-ray photoelectron spectroscopy proves that the ratio of adsorbed molecules can be arbitrarily adjusted via the molar fractions in solution. As a function of these molar fractions core level shifts are observed which are attributed to local work-function changes. By simulating the electric dipole field distribution, the continuous core level shifts are ascribed to a homogeneous mixture of molecules with different end groups adsorbed on adjacent lattice sites. Near-edge x-ray absorption fine structure measurements reveal formation of well-ordered SAMs. Despite the difference in dipole moment of the end groups, the molecular tilt and twist angles are identical for both single-component SAMs and a 1:1 mixed SAM.
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Affiliation(s)
- Daniel Brete
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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33
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Zhou XR, Zhong SA, Jiang GS. Computer simulation and synthesis of stimuli-responsive polymer by sol-gel for selective recognition of (4-chloro-2-methylphenoxy)acetic acid. POLYM INT 2012. [DOI: 10.1002/pi.4275] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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