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Xu X, Gao C, Emusani R, Jia C, Xiang D. Toward Practical Single-Molecule/Atom Switches. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2400877. [PMID: 38810145 PMCID: PMC11304318 DOI: 10.1002/advs.202400877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/29/2024] [Indexed: 05/31/2024]
Abstract
Electronic switches have been considered to be one of the most important components of contemporary electronic circuits for processing and storing digital information. Fabricating functional devices with building blocks of atomic/molecular switches can greatly promote the minimization of the devices and meet the requirement of high integration. This review highlights key developments in the fabrication and application of molecular switching devices. This overview offers valuable insights into the switching mechanisms under various stimuli, emphasizing structural and energy state changes in the core molecules. Beyond the molecular switches, typical individual metal atomic switches are further introduced. A critical discussion of the main challenges for realizing and developing practical molecular/atomic switches is provided. These analyses and summaries will contribute to a comprehensive understanding of the switch mechanisms, providing guidance for the rational design of functional nanoswitch devices toward practical applications.
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Affiliation(s)
- Xiaona Xu
- Institute of Modern Optics and Center of Single Molecule SciencesNankai UniversityTianjin Key Laboratory of Micro‐scale Optical Information Science and TechnologyTianjin300350China
| | - Chunyan Gao
- Institute of Modern Optics and Center of Single Molecule SciencesNankai UniversityTianjin Key Laboratory of Micro‐scale Optical Information Science and TechnologyTianjin300350China
| | - Ramya Emusani
- Institute of Modern Optics and Center of Single Molecule SciencesNankai UniversityTianjin Key Laboratory of Micro‐scale Optical Information Science and TechnologyTianjin300350China
| | - Chuancheng Jia
- Institute of Modern Optics and Center of Single Molecule SciencesNankai UniversityTianjin Key Laboratory of Micro‐scale Optical Information Science and TechnologyTianjin300350China
| | - Dong Xiang
- Institute of Modern Optics and Center of Single Molecule SciencesNankai UniversityTianjin Key Laboratory of Micro‐scale Optical Information Science and TechnologyTianjin300350China
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2
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Svatek S, Sacchetti V, Rodríguez-Pérez L, Illescas BM, Rincón-García L, Rubio-Bollinger G, González MT, Bailey S, Lambert CJ, Martín N, Agraït N. Enhanced Thermoelectricity in Metal-[60]Fullerene-Graphene Molecular Junctions. NANO LETTERS 2023; 23:2726-2732. [PMID: 36970777 PMCID: PMC10103166 DOI: 10.1021/acs.nanolett.3c00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 03/14/2023] [Indexed: 06/18/2023]
Abstract
The thermoelectric properties of molecular junctions consisting of a metal Pt electrode contacting [60]fullerene derivatives covalently bound to a graphene electrode have been studied by using a conducting-probe atomic force microscope (c-AFM). The [60]fullerene derivatives are covalently linked to the graphene via two meta-connected phenyl rings, two para-connected phenyl rings, or a single phenyl ring. We find that the magnitude of the Seebeck coefficient is up to nine times larger than that of Au-C60-Pt molecular junctions. Moreover, the sign of the thermopower can be either positive or negative depending on the details of the binding geometry and on the local value of the Fermi energy. Our results demonstrate the potential of using graphene electrodes for controlling and enhancing the thermoelectric properties of molecular junctions and confirm the outstanding performance of [60]fullerene derivatives.
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Affiliation(s)
- Simon
A. Svatek
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday 9, Ciudad Universitaria
de Cantoblanco, 28049 Madrid, Spain
- Departamento
de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente
7, 28049 Madrid, Spain
| | - Valentina Sacchetti
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday 9, Ciudad Universitaria
de Cantoblanco, 28049 Madrid, Spain
- Organic
Chemistry Department, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Laura Rodríguez-Pérez
- Organic
Chemistry Department, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Beatriz M. Illescas
- Organic
Chemistry Department, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Laura Rincón-García
- Departamento
de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente
7, 28049 Madrid, Spain
| | - Gabino Rubio-Bollinger
- Departamento
de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente
7, 28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia
de Materiales “Nicolás Cabrera” (INC), Facultad
de Ciencias, Universidad Autónoma
de Madrid, C/Francisco
Tomás y Valiente 7, 28049 Madrid, Spain
| | - M. Teresa González
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday 9, Ciudad Universitaria
de Cantoblanco, 28049 Madrid, Spain
| | - Steven Bailey
- Department
of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Colin J. Lambert
- Department
of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Nazario Martín
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday 9, Ciudad Universitaria
de Cantoblanco, 28049 Madrid, Spain
- Organic
Chemistry Department, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Nicolás Agraït
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday 9, Ciudad Universitaria
de Cantoblanco, 28049 Madrid, Spain
- Departamento
de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente
7, 28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia
de Materiales “Nicolás Cabrera” (INC), Facultad
de Ciencias, Universidad Autónoma
de Madrid, C/Francisco
Tomás y Valiente 7, 28049 Madrid, Spain
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Li P, Hou S, Alharbi B, Wu Q, Chen Y, Zhou L, Gao T, Li R, Yang L, Chang X, Dong G, Liu X, Decurtins S, Liu SX, Hong W, Lambert CJ, Jia C, Guo X. Quantum Interference-Controlled Conductance Enhancement in Stacked Graphene-like Dimers. J Am Chem Soc 2022; 144:15689-15697. [PMID: 35930760 DOI: 10.1021/jacs.2c05909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stacking interactions are of significant importance in the fields of chemistry, biology, and material optoelectronics because they determine the efficiency of charge transfer between molecules and their quantum states. Previous studies have proven that when two monomers are π-stacked in series to form a dimer, the electrical conductance of the dimer is significantly lower than that of the monomer. Here, we present a strong opposite case that when two anthanthrene monomers are π-stacked to form a dimer in a scanning tunneling microscopic break junction, the conductance increases by as much as 25 in comparison with a monomer, which originates from a room-temperature quantum interference. Remarkably, both theory and experiment consistently reveal that this effect can be reversed by changing the connectivity of external electrodes to the monomer core. These results demonstrate that synthetic control of connectivity to molecular cores can be combined with stacking interactions between their π systems to modify and optimize charge transfer between molecules, opening up a wide variety of potential applications ranging from organic optoelectronics and photovoltaics to nanoelectronics and single-molecule electronics.
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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, P. R. China
| | - Songjun Hou
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Bader Alharbi
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.,Department of Physics, Prince Sattam Bin Abdulaziz University, Alkharj 16278, Saudi Arabia
| | - Qingqing Wu
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - 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, P. R. 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, P. R. China
| | - Tengyang Gao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Ruihao Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Lan Yang
- 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, P. R. China
| | - Xinyue Chang
- 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, P. R. China
| | - Gang Dong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Xunshan Liu
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.,Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, P. R. China
| | - Silvio Decurtins
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Shi-Xia Liu
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - 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, P. R. 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, P. R. 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, P. R. 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, P. R. China
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Almughathawi R, Hou S, Wu Q, Liu Z, Hong W, Lambert C. Conformation and Quantum-Interference-Enhanced Thermoelectric Properties of Diphenyl Diketopyrrolopyrrole Derivatives. ACS Sens 2021; 6:470-476. [PMID: 33382942 PMCID: PMC8021221 DOI: 10.1021/acssensors.0c02043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Manipulating the connectivity of external electrodes to central rings of carbon-based molecules in single molecule junctions is an effective route to tune their thermoelectrical properties. Here we investigate the connectivity dependence of the thermoelectric properties of a series of thiophene-diketopyrrolopyrrole (DPP) derivative molecules using density functional theory and tight-binding modeling, combined with quantum transport theory. We find a significant dependence of electrical conductance on the connectivity of the two thiophene rings attached to the DPP core. Interestingly, for connectivities corresponding to constructive quantum interference (CQI), different isomers obtained by rotating the thiophene rings possess the same electrical conductance while those corresponding to destructive quantum interference (DQI) show huge conductance variations upon ring rotation. Furthermore, we find that DQI connectivity leads to enhanced Seebeck coefficients, which can reach 500-700 μV/K. After including the contribution to the thermal conductance from phonons, the full figure of merit (ZT) for the CQI molecules could reach 1.5 at room temperature and it would further increase to 2 when temperature elevates to 400 K. Finally, we demonstrate that doping with tetracyanoquinodimethane can change the sign of the Seebeck coefficients by forming a charge-transfer system with the DPP.
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Affiliation(s)
- Renad Almughathawi
- Physics Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
| | - Songjun Hou
- Physics Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
| | - Qingqing Wu
- Physics Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
| | - Zitong Liu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, NEL, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Colin Lambert
- Physics Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
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5
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Shirdel-Havar M, Farghadan R. Thermal magnetoresistance and spin thermopower in C 60 dimers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:285302. [PMID: 32308207 DOI: 10.1088/1361-648x/ab8154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We theoretically investigate the spin-related thermoelectric properties in C60 dimer bridged between zigzag graphene nanoribbon electrodes using the tight-binding model, equilibrium Green's function method, and Landauer-Büttiker transport formalism. By applying a thermal gradient, our proposed device could generate a notable spin thermopower. Moreover, by switching the magnetization of the electrodes, different spin currents, and giant thermal magnetoresistance (MR) can be achieved. Interestingly, various types of C60 dimers also produce a thermal MR, which is sensitively modified by the gate voltages.
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6
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Multifunctional conjugated 1,6-heptadiynes and its derivatives stimulated molecular electronics: Future moletronics. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2019.109467] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Sadeghi H. Quantum and Phonon Interference-Enhanced Molecular-Scale Thermoelectricity. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:12556-12562. [PMID: 32064012 PMCID: PMC7011773 DOI: 10.1021/acs.jpcc.8b12538] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 04/21/2019] [Indexed: 05/31/2023]
Abstract
Simultaneous engineering of electron and phonon transport through nanoscale molecular junctions is fundamental to the development of high-performance thermoelectric materials for the conversion of waste heat into electricity and cooling. Here, we demonstrate a systematic improvement of the room-temperature thermoelectric figure of merit (ZT) of molecular junctions. This is achieved by phonon interference (PI)-suppressed thermal conductance and quantum interference-enhanced electrical conductance and Seebeck coefficient. This strategy leads to a significant enhancement of ZT from low values ca. 10-6 in oligo(phenylene-ethynylene) (OPE2) to the record values of 2.4 in dinitro-functionalized OPE2 (DOPE2). The dinitro functionalization also considerably enhances ZT of biphenyl-dithiol (BDT) and bipyridyl molecular junctions. Remarkably, the energy levels of electron-withdrawing nitro groups are hardly changed from one molecule to the other. Because of this generic feature, a resonance transport in the vicinity of Fermi energy of electrodes is formed leading to a significant improvement of Seebeck coefficient and ZT of all derivatives. For example, the Seebeck coefficient enhances from 10.8 μV/K in BDT to -470 μV/K in dinitro-BDT (DBDT). In addition, destructive PI due to the nitro groups suppresses phonon thermal conductance, for example, from 20 pW/K in BDT to 11 pW/K in DBDT at room temperature. We also demonstrate that quantum and PI-enhanced single-molecule thermoelectric efficiency is conserved when parallel molecules are placed between gold electrodes. These results promise to remove the key roadblocks and open new avenues to exploit functionalized organic molecules for thermoelectric energy harvesting and cooling.
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Abstract
Full-carbon electronics at the scale of several angstroms is an expeimental challenge, which could be overcome by exploiting the versatility of carbon allotropes. Here, we investigate charge transport through graphene/single-fullerene/graphene hybrid junctions using a single-molecule manipulation technique. Such sub-nanoscale electronic junctions can be tuned by band gap engineering as exemplified by various pristine fullerenes such as C60, C70, C76 and C90. In addition, we demonstrate further control of charge transport by breaking the conjugation of their π systems which lowers their conductance, and via heteroatom doping of fullerene, which introduces transport resonances and increase their conductance. Supported by our combined density functional theory (DFT) calculations, a promising future of tunable full-carbon electronics based on numerous sub-nanoscale fullerenes in the large family of carbon allotropes is anticipated. All-carbon electronics holds promise beyond the conventional silicon-based electronics, but it remains challenging to manufacture them with well-defined structures thus tunability. Tan et al. control charge transport in single-molecule junctions using different fullerenes between graphene electrodes.
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Hou S, Wu Q, Sadeghi H, Lambert CJ. Thermoelectric properties of oligoglycine molecular wires. NANOSCALE 2019; 11:3567-3573. [PMID: 30632577 DOI: 10.1039/c8nr08878k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We have investigated the electrical and thermoelectrical properties of glycine chains with and without cysteine terminal groups. The electrical conductance of (Gly)n, (Gly)nCys and Cys(Gly)nCys molecules (where Gly, Cys represent glycine and cysteine and n = 1-3) was found to decay exponentially with length l as e-βl. Our results show that connecting the molecules to gold electrodes via the sulphur atom of the cysteine moiety leads to higher β factors of 1.57 Å-1 and 1.22 Å-1 for (Gly)nCys and Cys(Gly)nCys respectively, while β = 0.92 Å-1 for (Gly)n. We also find that replacing the peptide bond with a methylene group (-CH2-) increases the conductance of (Gly)3Cys. Furthermore, we find the (Gly)1Cys and Cys(Gly)1Cys systems show good thermoelectrical performance, because of their high Seebeck coefficients (∼0.2 mV K-1) induced by the sulphur of the cysteine(s). With the contributions of both electrons and phonons taken into consideration, a high figure of merit ZT = 0.8 is obtained for (Gly)1Cys at room temperature, which increases further with increasing temperature, suggesting that peptide-based SAM junctions are promising candidates for thermoelectric energy harvesting.
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Affiliation(s)
- Songjun Hou
- Quantum Technology Centre, Department of Physics, Lancaster University, LA1 4YB Lancaster, UK.
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Wu Q, Sadeghi H, Lambert CJ. MoS 2 nano flakes with self-adaptive contacts for efficient thermoelectric energy harvesting. NANOSCALE 2018; 10:7575-7580. [PMID: 29637971 DOI: 10.1039/c8nr01635f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We examine the potential of the low-dimensional material MoS2 for the efficient conversion of waste heat to electricity via the Seebeck effect. Recently monolayer MoS2 nano flakes with self-adaptive Mo6S6 contacts were formed, which take advantage of mechanical stability and chemical covalent bonding to the MoS2. Here, we study the thermoelectric properties of these junctions by calculating their conductance, thermopower and thermal conductance due to both electrons and phonons. We show that thermoelectric figures of merit ZT as high as ∼2.8 are accessible in these junctions, independent of the flake size and shape, provided the Fermi energy is close to a band edge. We show that Nb dopants as substituents for Mo atoms can be used to tune the Fermi energy, and despite the associated inhomogeneous broadening, room temperature values as high as ZT ∼ 0.6 are accessible, increasing to 0.8 at 500 K.
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Affiliation(s)
- Qingqing Wu
- Quantum Technology Centre, Physics Department, Lancaster University, LA1 4YB Lancaster, UK.
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Wu Q, Hou S, Sadeghi H, Lambert CJ. A single-molecule porphyrin-based switch for graphene nano-gaps. NANOSCALE 2018; 10:6524-6530. [PMID: 29570203 DOI: 10.1039/c8nr00025e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Stable single-molecule switches with high on-off ratios are an essential component for future molecular-scale circuitry. Unfortunately, devices using gold electrodes are neither complementary metal-oxide-semiconductor (CMOS) compatible nor stable at room temperature. To overcome these limitations, several groups have been developing electroburnt graphene electrodes for single molecule electronics. Here, in anticipation of these developments, we examine how the electrical switching properties of a series of porphyrin molecules with pendant dipoles can be tuned by systematically increasing the number of spacer units between the porphyrin core and graphene electrodes. The porphyrin is sandwiched between a graphene source and drain and gated by a third electrode. It is found that the system has two stable states with high and low conductances, which can be controlled by coupling the dipole of the functionalised porphyrin to an external electric field. The associated rotation leads to the breaking of conjugation and a decrease in electrical conductances. As the number of spacers is increased, the conductance ratio can increase from 100 with one spacer to 200 with four spacers. This switching ratio is further enhanced by decreasing the temperature, reaching approximately 2200 at 100 K. This design for a molecular switch using graphene electrodes could be extended to other aromatic systems.
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Affiliation(s)
- Qingqing Wu
- Quantum Technology Centre, Lancaster University, LA1 4YB Lancaster, UK.
| | - Songjun Hou
- Quantum Technology Centre, Lancaster University, LA1 4YB Lancaster, UK.
| | - Hatef Sadeghi
- Quantum Technology Centre, Lancaster University, LA1 4YB Lancaster, UK.
| | - Colin J Lambert
- Quantum Technology Centre, Lancaster University, LA1 4YB Lancaster, UK.
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