1
|
Park J, Park S. Molecular Engineering for Future Thermoelectric Materials: The Role of Electrode and Metal Components in Molecular Junctions. CHEMSUSCHEM 2025; 18:e202402077. [PMID: 39582066 DOI: 10.1002/cssc.202402077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2024] [Revised: 11/24/2024] [Accepted: 11/24/2024] [Indexed: 11/26/2024]
Abstract
As global temperatures increase due to climate change, the accumulation of excess heat on Earth presents a valuable resource that can be harnessed for electricity generation using thermoelectric materials. However, the intricate structures of bulk thermoelectric materials pose significant challenges to their comprehensive understanding and limit performance. Additionally, their relatively high production costs present practical obstacles. A promising solution to these issues lies in molecular control and the use of molecular junctions. Molecules are predicted to surpass the performance of existing bulk materials in energy conversion because they can be chemically tuned to achieve high thermoelectric efficiencies. This review identifies the thermoelectric parameters that affect the performance of molecular junctions. It also explores various experimental platforms for measuring thermoelectric performance from single molecules to assemblies of hundreds of molecules. Finally, it highlights recent advancements in thermoelectric molecular junctions, focusing on the crucial roles of electrodes and metal components within the molecules, such as Ru complexes, metalloporphyrins, metallocenes, conjugated silane wires, and endohedral metallofullerenes. Ultimately, our review provides a comprehensive analysis of strategies to enhance the thermoelectric efficiency of molecular junctions.
Collapse
Affiliation(s)
- Jiwoo Park
- School of Chemistry and Energy, Sungshin Women's University, Seoul, 01133, Republic of Korea
| | - Sohyun Park
- School of Chemistry and Energy, Sungshin Women's University, Seoul, 01133, Republic of Korea
| |
Collapse
|
2
|
Ji X, Qi Q, Chen Y, Zhou C, Yu X. A Three-Tiered Hierarchical Computational Framework Bridging Molecular Systems and Junction-Level Charge Transport. J Chem Theory Comput 2025; 21:2961-2976. [PMID: 40048239 DOI: 10.1021/acs.jctc.4c01711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2025]
Abstract
The nonequilibrium Green's function (NEGF) method combined with ab initio calculations has been widely used to study charge transport in molecular junctions. However, the significant computational demands of high-resolution calculations for all device components pose challenges in simulating junctions with complex molecular junction structures and understanding the functionality of molecular devices. In this study, we developed a series of computational methods capable of effectively handling the molecular Hamiltonian, electrode electronic structures, and their interfacial coupling at different theoretical levels. As three-tiered hierarchical levels, they enable efficient charge transport computations ranging from individual molecules to complete junction systems, achieving an optimal balance between computational cost and accuracy. Moreover, integrated into a Question-Driven Hierarchical Computation (QDHC) framework, we show this three-tiered framework is able to address specific research objectives by isolating and analyzing the dominant factors governing charge transport, thus significantly enhancing the efficiency of analyzing charge transport mechanisms, as validated through a series of benchmark studies on diverse molecular junction systems.
Collapse
Affiliation(s)
- Xuan Ji
- Key Laboratory of Organic Integrated Circuit, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Qiang Qi
- Key Laboratory of Organic Integrated Circuit, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Yueqi Chen
- Key Laboratory of Organic Integrated Circuit, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Chen Zhou
- Key Laboratory of Organic Integrated Circuit, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Xi Yu
- Key Laboratory of Organic Integrated Circuit, Ministry of Education & Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| |
Collapse
|
3
|
Fang C, Li Y, Wang S, Liang M, Yan C, Liu J, Hong W. Thermoelectric and thermal properties of molecular junctions: mechanisms, characterization methods and applications. Chem Commun (Camb) 2025; 61:4447-4464. [PMID: 40007208 DOI: 10.1039/d4cc06822j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2025]
Abstract
The rapid development of artificial intelligence requires tremendous energy consumption. Due to the limitations of cooling and energy recovery systems, effectively lowering power dissipation and utilizing the waste heat of electronic devices remain challenges. Molecular electronics, with its potential for low energy consumption and high-efficiency thermoelectric conversion, offers a feasible solution for future computational devices. Over the past two decades, researchers have made significant progress in the study of thermal and thermoelectric properties of molecular junctions. In this feature article, we first introduced four mechanisms of thermal and thermoelectric transport in molecular junctions guided by quantum theory. We then reviewed the evolution of characterization techniques for assessing the local temperature, thermopower, and thermal conductance of molecular junctions. Subsequently, we introduced the practical applications that have been implemented so far. This review concludes by addressing the principal challenges currently faced in the field and identifying crucial directions for future research.
Collapse
Affiliation(s)
- Chao Fang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Yuting Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Siwen Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Mingchen Liang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Chenshuai Yan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Institute of Artificial Intelligence & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, China.
| |
Collapse
|
4
|
Gao Y, Leary E, Palomino-Ruiz L, Malagón JM, González MT, Krempe M, Johnson M, Tykwinski RR. Length-Dependent Conduction of Polyynes: Searching for the Limit of the Tunneling Regime. J Am Chem Soc 2025; 147:4052-4059. [PMID: 39847010 DOI: 10.1021/jacs.4c12895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2025]
Abstract
Rigid, conjugated molecules are excellent candidates as molecular wires since they can achieve full extension between electrodes while maintaining conjugation. Molecular design can be used to minimize the accessible pi surface and interactions between the bridging wire and the electrode. Polyynes are archetypal molecular wires that feature a rigid molecular framework with a cross-section of a single carbon atom. Understanding the behavior of polyynes in molecular junctions is essential for testing models of length versus electron transport. We report the construction of molecular junctions using polyynes with a well-defined length up to ca. 5 nm in devices characterized by scanning tunneling microscopy break junctions. The polyynes, Py**[n] (n = 4, 6, 8, 10, 12, 16), are end-capped with pyridyl groups, and we demonstrate good agreement between the length of the molecular junction and the calculated molecular length, with an average discrepancy of just 0.1 nm. This highlights the power of STM-BJ experiments to accurately determine the molecular length. The range of molecular lengths, from 1.8 to 4.8 nm, mark this as the most accurate determination of β in polyynes to date (β = 2.2 ± 0.1 nm-1). We have applied a model based on the single and triple bond lengths to interpret β-values, which predicts β = 1.9 nm-1, consistent with the experimental value. This model also confirms that electronic coupling in polyynes is unaffected by the rotation about the single bonds. At all molecular lengths, we observe conductance in the tunneling regime due to the long effective conjugation length of polyynes.
Collapse
Affiliation(s)
- Yueze Gao
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Edmund Leary
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Lucía Palomino-Ruiz
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
- Departamento de Química Orgánica, Facultad de Ciencias, Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada, 18071 Granada, Spain
| | - José M Malagón
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - M Teresa González
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Maximilian Krempe
- Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91052 Erlangen, Germany
| | - Matthew Johnson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| | - Rik R Tykwinski
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2
| |
Collapse
|
5
|
He P, Jang J, Kang H, Yoon HJ. Thermoelectricity in Molecular Tunnel Junctions. Chem Rev 2025. [PMID: 39908450 DOI: 10.1021/acs.chemrev.4c00886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2025]
Abstract
The growing interest in thermoelectric energy conversion technologies has recently extended to the molecular scale, with molecular tunnel junctions emerging as promising platforms for energy harvesting from heat in a quantum-tunneling regime. This Review explores the advances in thermoelectricity within molecular junctions, highlighting the unique ability of these junctions to exploit charge tunneling and controlled molecular structure to enhance thermoelectric performance. Molecular thermoelectrics, which bridge nanoscale material design and thermoelectric applications, utilize tunneling mechanisms, such as coherent tunneling and hopping processes, including coherent and incoherent pathways, to facilitate energy conversion. Complementing these mechanisms is an array of high-precision fabrication techniques for molecular junctions, from single-molecule break junctions to large-area liquid metal-based systems, each tailored to optimize heat and charge transfer properties. With novel design strategies such as the incorporation of electron-dense ligands, customizable anchor groups, and advanced junction architectures, molecular tunnel junctions hold promise for addressing challenging targets in thermoelectricity. This Review focuses on theoretical models, experimental methodologies, and design principles aimed at understanding the thermoelectric function in molecular junctions and enhancing the performance.
Collapse
Affiliation(s)
- Peng He
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Jiung Jang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hungu Kang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
| |
Collapse
|
6
|
Bergfield JP. Identifying Quantum Interference Effects from Joint Conductance-Thermopower Statistics. NANO LETTERS 2024; 24:15110-15117. [PMID: 39536132 PMCID: PMC11613687 DOI: 10.1021/acs.nanolett.4c04439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2024] [Revised: 10/30/2024] [Accepted: 11/05/2024] [Indexed: 11/16/2024]
Abstract
Although quantum effects are thought to dominate the heat and charge transport through molecular junctions, large uncertainties in chemical structure, lead-molecule coupling strengths, and energy levels make it difficult to definitively identify these effects from the measured thermopower S and conductance G distributions alone. Here, we develop a simple statistical method to identify destructive quantum interference features (nodes) through the anticorrelation between simultaneously measured G and S values. We find these correlations can be used to unambiguously identify far-detuned nodes, even when G and S distributions alone cannot. As an example, we consider several para- and meta-configured systems, including benzenediamine and diiodo-terphenyl-based junctions, finding that nodes can be identified in ensembles with broad level-alignment and lead-molecule coupling distributions, and with significant anodal transport contributions, including from vacuum tunneling. The efficacy and limitations of this method are analyzed.
Collapse
Affiliation(s)
- Justin P. Bergfield
- Department
of Physics, Illinois State University, Normal, Illinois 61790, United States
- Department
of Chemistry, Illinois State University, Normal, Illinois 61790, United States
| |
Collapse
|
7
|
Schmidt M, Abellán Vicente L, González MT, Zotti LA, Esser B, Leary E. Low-lying LUMO Boosts Conductance in Antiaromatic Dibenzopentalene Versus Aromatic Analogues. Chemistry 2024; 30:e202400935. [PMID: 38752711 DOI: 10.1002/chem.202400935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Indexed: 06/28/2024]
Abstract
Antiaromaticity is a fundamental concept in chemistry, but the study of molecular wires incorporating antiaromatic units is limited. Despite initial predictions, very few studies show that antiaromaticity has a beneficial effect on electron transport. Dibenzo[a,e]pentalene (DBP) is a stable structure that displays appreciable antiaromaticity within the five-membered rings of the pentalene core. We have investigated derivatives of DBP furnished with pyridyl (Py) and F4-pyridyl (PyF4) anchor groups, and compared the conductance with purely aromatic phenyl and anthracene analogues. We find that the low-bias conductance of DBP-Py is approximately 60 % larger than that of the anthracene analogue Anth-Py and 250 % larger compared to the phenyl derivative Ph-Py. This is due to a better alignment of the LUMO with the gold Fermi level, which we confirm by conductance-voltage spectroscopy where the conductance of DBP-Py shows the greatest voltage-dependence. The F4-pyridyl compounds, which have lower LUMO energies compared to the pyridyl analogues, did not, however, form detectable molecular junctions. The strongly electron-withdrawing fluorine atoms reduce the donor capability of the nitrogen lone-pair to the point where stable N-Au bonds no longer form.
Collapse
Affiliation(s)
- Maximilian Schmidt
- Institute of Organic Chemistry II and Advanced Materials, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Lydia Abellán Vicente
- Fundación IMDEA Nanociencia, Calle Faraday 9 Campus Universitario de Cantoblanco, 28049, Madrid, Spain
| | - M Teresa González
- Fundación IMDEA Nanociencia, Calle Faraday 9 Campus Universitario de Cantoblanco, 28049, Madrid, Spain
| | - Linda A Zotti
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, 28049, Madrid, Spain
- Institute of Condensed Matter Physics (IFIMAC), Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Birgit Esser
- Institute of Organic Chemistry II and Advanced Materials, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Edmund Leary
- Fundación IMDEA Nanociencia, Calle Faraday 9 Campus Universitario de Cantoblanco, 28049, Madrid, Spain
| |
Collapse
|
8
|
Alotaibi T, Alshahrani M, Alshammari M, Alotaibi M, Taha TAM, Al-Jobory AA, Ismael A. Orientational Effects and Molecular-Scale Thermoelectricity Control. ACS OMEGA 2024; 9:29537-29543. [PMID: 39005829 PMCID: PMC11238236 DOI: 10.1021/acsomega.4c02141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 07/16/2024]
Abstract
The orientational effect concept in a molecular-scale junction is established for asymmetric junctions, which requires the fulfillment of two conditions: (1) design of an asymmetric molecule with strong distinct terminal end groups and (2) construction of a doubly asymmetric junction by placing an asymmetric molecule in an asymmetric junction to form a multicomponent system such as Au/Zn-TPP+M/Au. Here, we demonstrate that molecular-scale junctions that satisfy the conditions of these effects can manifest Seebeck coefficients whose sign fluctuates depending on the orientation of the molecule within the asymmetric junction in a complete theoretical investigation. Three anthracene-based compounds are investigated in three different scenarios, one of which displays a bithermoelectric behavior due to the presence of strong anchor groups, including pyridyl and thioacetate. This bithermoelectricity demonstration implies that if molecules with alternating orientations can be placed between an asymmetric source and drain, they can be potentially utilized for increasing the thermovoltage in molecular-scale thermoelectric energy generators (TEGs).
Collapse
Affiliation(s)
- Turki Alotaibi
- Department
of Physics, College of Science, Jouf University, Sakaka 72388, Saudi Arabia
| | - Maryam Alshahrani
- Department
of Physics, College of Science, University
of Bisha, P.O. Box 551, Bisha 61922, Saudi Arabia
| | - Majed Alshammari
- Department
of Physics, College of Science, Jouf University, Sakaka 72388, Saudi Arabia
| | - Moteb Alotaibi
- Department
of Physics, College of Science and Humanities in Al-Kharj, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
| | - Taha Abdel Mohaymen Taha
- Physics
and Engineering Mathematics Department, Faculty of Electronic Engineering, Menoufia University, Menouf 32952, Egypt
| | - Alaa A. Al-Jobory
- Department
of Physics, College of Science, University
of Anbar, Anbar 31001, Iraq
| | - Ali Ismael
- Department
of Physics, Lancaster University, Lancaster LA1 4YB, U.K.
- Department
of Physics, College of Education for Pure Science, Tikrit University, Tikrit 3400, Iraq
| |
Collapse
|
9
|
Yang J, Li Y, Zhang Z, Li H. A bias voltage controlled electrode-molecule interface in single-molecule junctions. Chem Commun (Camb) 2024; 60:5980-5983. [PMID: 38769815 DOI: 10.1039/d4cc01143k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Tuning the electrode-molecule interface stands at the heart of functional single-molecule devices. Herein, we report that the electrode-molecule interface of difluoro-substituted benzothiadiazole (FBTZ)-based single-molecule junctions can be modulated by the bias voltage. At low bias voltage (100 mV), the dative Au-N linkage is formed and at high bias voltage (600 mV), a covalent Au-C linkage is constructed. These junctions show distinct conductance. Interestingly, dominant charge carriers in Au-N- and Au-C-based junctions are different, as evidenced by dft calculations. These results provide a new strategy for regulating the electrode-molecule interface, which will advance the development of molecular electronics.
Collapse
Affiliation(s)
- Jiawei Yang
- Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, P. R. China.
| | - Yunpeng Li
- Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, P. R. China.
| | - Zekai Zhang
- Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, P. R. China.
| | - Hongxiang Li
- Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, P. R. China.
| |
Collapse
|
10
|
Qi Q, Tian G, Ma L. Enhancing the thermopower of single-molecule junctions by edge substitution effects. Phys Chem Chem Phys 2024; 26:11340-11346. [PMID: 38564269 DOI: 10.1039/d3cp06176k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Heteroatom substitution and anchoring groups have an important impact on the thermoelectric properties of single-molecule junctions. Herein, thermoelectric properties of several anthracene derivative based single-molecule junctions are studied by means of first-principles calculations. In particular, we pay great attention to the edge substitution effects and find that edge substitution with nitrogen can induce a transmission peak near the Fermi energy, leading to large transmission coefficients and electrical conductance at the Fermi energy. Additionally, the steep shape of the transmission function gives rise to a high Seebeck coefficient. Therefore, an enhanced power factor can be expected. The robustness of this edge substitution effect has been examined by altering the electrode distance and introducing heteroatoms at different positions. The enhancement of the power factor due to edge substitution makes the studied single-molecule junction a promising candidate for efficient thermoelectric devices.
Collapse
Affiliation(s)
- Qiang Qi
- State Key Laboratory of Metastable Material Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Guangjun Tian
- State Key Laboratory of Metastable Material Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Liang Ma
- State Key Laboratory of Metastable Material Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| |
Collapse
|
11
|
Chen L, Yang Z, Lin Q, Li X, Bai J, Hong W. Evolution of Single-Molecule Electronic Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1988-2004. [PMID: 38227964 DOI: 10.1021/acs.langmuir.3c03104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Single-molecule electronics can fabricate single-molecule devices via the construction of molecule-electrode interfaces and also provide a unique tool to investigate single-molecule scale physicochemical processes at these interfaces. To investigate single-molecule electronic devices with desired functionalities, an understanding of the interface evolution processes in single-molecule devices is essential. In this review, we focus on the evolution of molecule-electrode interface properties, including the background of interface evolution in single-molecule electronics, the construction of different types of single-molecule interfaces, and the regulation methods. Finally, we discuss the perspective of future characterization techniques and applications for single-molecule electronic interfaces.
Collapse
Affiliation(s)
- Lichuan Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| | - Zixian Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| | - Qichao Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| | - Xiaohui Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| | - Jie Bai
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & College of Materials & IKKEM, Xiamen University, Xiamen 361000, China
| |
Collapse
|
12
|
Lawson B, Skipper HE, Kamenetska M. Phenol is a pH-activated linker to gold: a single molecule conductance study. NANOSCALE 2024; 16:2022-2029. [PMID: 38197186 DOI: 10.1039/d3nr05257e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Single molecule conductance measurements typically rely on functional linker groups to anchor the molecule to the conductive electrodes through a donor-acceptor or covalent bond. While many linking moieties, such as thiols, amines, thiothers and phosphines have been used among others, very few involve oxygen binding directly to gold electrodes. Here, we report successful single molecule conductance measurements using hydroxy (OH)-containing phenol linkers and show that the molecule-gold attachment and electron transport are mediated by a direct O-Au bond. We find that deprotonation of the hydroxy moiety is necessary for metal-molecule binding to proceed, so that junction formation can be activated through pH control. Electronic structure and DFT+Σ transport calculations confirm our experimental findings that phenolate-terminated alkanes can anchor on the gold and show charge transport trends consistent with prior observations of alkane conductance with other linker groups. Critically, the deprotonated O--Au binding shows features similar to the thiolate-Au bond, but without the junction disruption caused by intercalation of sulfur into electrode tips often observed with thiol-terminated molecules. By comparing the conductance and binding features of O-Au and S-Au bonds, this study provides insight into the aspects of Au-linker bonding that promote reproducible and robust single molecule junction measurements.
Collapse
Affiliation(s)
- Brent Lawson
- Department of Physics, Boston University, Boston, Massachusetts, 02215, USA.
| | - Hannah E Skipper
- Department of Chemistry, Boston University, Boston, Massachusetts, 02215, USA
| | - Maria Kamenetska
- Department of Physics, Boston University, Boston, Massachusetts, 02215, USA.
- Department of Chemistry, Boston University, Boston, Massachusetts, 02215, USA
- Division of Material Science and Engineering, Boston, Massachusetts, 02215, USA
| |
Collapse
|
13
|
Mejía L, Cossio P, Franco I. Microscopic theory, analysis, and interpretation of conductance histograms in molecular junctions. Nat Commun 2023; 14:7646. [PMID: 37996422 PMCID: PMC10667247 DOI: 10.1038/s41467-023-43169-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 11/02/2023] [Indexed: 11/25/2023] Open
Abstract
Molecular electronics break-junction experiments are widely used to investigate fundamental physics and chemistry at the nanoscale. Reproducibility in these experiments relies on measuring conductance on thousands of freshly formed molecular junctions, yielding a broad histogram of conductance events. Experiments typically focus on the most probable conductance, while the information content of the conductance histogram has remained unclear. Here we develop a microscopic theory for the conductance histogram by merging the theory of force-spectroscopy with molecular conductance. The procedure yields analytical equations that accurately fit the conductance histogram of a wide range of molecular junctions and augments the information content that can be extracted from them. Our formulation captures contributions to the conductance dispersion due to conductance changes during the mechanical elongation inherent to the experiments. In turn, the histogram shape is determined by the non-equilibrium stochastic features of junction rupture and formation. The microscopic parameters in the theory capture the junction's electromechanical properties and can be isolated from separate conductance and rupture force (or junction-lifetime) measurements. The predicted behavior can be used to test the range of validity of the theory, understand the conductance histograms, design molecular junction experiments with enhanced resolution and molecular devices with more reproducible conductance properties.
Collapse
Affiliation(s)
- Leopoldo Mejía
- Department of Chemistry, University of Rochester, Rochester, NY, 14627, USA.
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Pilar Cossio
- Center for Computational Mathematics, Flatiron Institute, New York City, NY, 10010, USA
- Center for Computational Biology, Flatiron Institute, New York City, NY, 10010, USA
- Biophysics of Tropical Diseases Max Planck Tandem Group, University of Antioquia, 050010, Medellín, Colombia
| | - Ignacio Franco
- Department of Chemistry, University of Rochester, Rochester, NY, 14627, USA.
- Department of Physics, University of Rochester, Rochester, NY, 14627, USA.
| |
Collapse
|
14
|
Oz A, Nitzan A, Hod O, Peralta JE. Electron Dynamics in Open Quantum Systems: The Driven Liouville-von Neumann Methodology within Time-Dependent Density Functional Theory. J Chem Theory Comput 2023; 19:7496-7504. [PMID: 37852250 PMCID: PMC10653109 DOI: 10.1021/acs.jctc.3c00311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Indexed: 10/20/2023]
Abstract
A first-principles approach to describe electron dynamics in open quantum systems driven far from equilibrium via external time-dependent stimuli is introduced. Within this approach, the driven Liouville-von Neumann methodology is used to impose open boundary conditions on finite model systems whose dynamics is described using time-dependent density functional theory. As a proof of concept, the developed methodology is applied to simple spin-compensated model systems, including a hydrogen chain and a graphitic molecular junction. Good agreement between steady-state total currents obtained via direct propagation and those obtained from the self-consistent solution of the corresponding Sylvester equation indicates the validity of the implementation. The capability of the new computational approach to analyze, from first principles, non-equilibrium dynamics of open quantum systems in terms of temporally and spatially resolved current densities is demonstrated. Future extensions of the approach toward the description of dynamical magnetization and decoherence effects are briefly discussed.
Collapse
Affiliation(s)
- Annabelle Oz
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
| | - Abraham Nitzan
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19103, United States
| | - Oded Hod
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
| | - Juan E. Peralta
- Department
of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, United States
| |
Collapse
|
15
|
Xu H, Fan H, Luan Y, Yan S, Martin L, Miao R, Pauly F, Meyhofer E, Reddy P, Linke H, Wärnmark K. Electrical Conductance and Thermopower of β-Substituted Porphyrin Molecular Junctions─Synthesis and Transport. J Am Chem Soc 2023; 145:23541-23555. [PMID: 37874166 PMCID: PMC10623571 DOI: 10.1021/jacs.3c07258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Indexed: 10/25/2023]
Abstract
Molecular junctions offer significant potential for enhancing thermoelectric power generation. Quantum interference effects and associated sharp features in electron transmission are expected to enable the tuning and enhancement of thermoelectric properties in molecular junctions. To systematically explore the effect of quantum interferences, we designed and synthesized two new classes of porphyrins, P1 and P2, with two methylthio anchoring groups in the 2,13- and 2,12-positions, respectively, and their Zn complexes, Zn-P1 and Zn-P2. Past theory suggests that P1 and Zn-P1 feature destructive quantum interference in single-molecule junctions with gold electrodes and may thus show high thermopower, while P2 and Zn-P2 do not. Our detailed experimental single-molecule break-junction studies of conductance and thermopower, the latter being the first ever performed on porphyrin molecular junctions, revealed that the electrical conductance of the P1 and Zn-P1 junctions is relatively close, and the same holds for P2 and Zn-P2, while there is a 6 times reduction in the electrical conductance between P1 and P2 type junctions. Further, we observed that the thermopower of P1 junctions is slightly larger than for P2 junctions, while Zn-P1 junctions show the largest thermopower and Zn-P2 junctions show the lowest. We relate the experimental results to quantum transport theory using first-principles approaches. While the conductance of P1 and Zn-P1 junctions is robustly predicted to be larger than those of P2 and Zn-P2, computed thermopowers depend sensitively on the level of theory and the single-molecule junction geometry. However, the predicted large difference in conductance and thermopower values between Zn-P1 and Zn-P2 derivatives, suggested in previous model calculations, is not supported by our experimental and theoretical findings.
Collapse
Affiliation(s)
- Hailiang Xu
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
| | - Hao Fan
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
| | - Yuxuan Luan
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Shen Yan
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - León Martin
- Institute
of Physics and Centre for Advanced Analytics and Predictive Sciences, University of Augsburg, 86159 Augsburg, Germany
| | - Ruijiao Miao
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Fabian Pauly
- Institute
of Physics and Centre for Advanced Analytics and Predictive Sciences, University of Augsburg, 86159 Augsburg, Germany
| | - Edgar Meyhofer
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Pramod Reddy
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Materials Science and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Heiner Linke
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Solid State
Physics, Lund University, Box 118, 22100 Lund, Sweden
| | - Kenneth Wärnmark
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
| |
Collapse
|
16
|
Li L, Prindle CR, Shi W, Nuckolls C, Venkataraman L. Radical Single-Molecule Junctions. J Am Chem Soc 2023; 145:18182-18204. [PMID: 37555594 DOI: 10.1021/jacs.3c04487] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Radicals are unique molecular systems for applications in electronic devices due to their open-shell electronic structures. Radicals can function as good electrical conductors and switches in molecular circuits while also holding great promise in the field of molecular spintronics. However, it is both challenging to create stable, persistent radicals and to understand their properties in molecular junctions. The goal of this Perspective is to address this dual challenge by providing design principles for the synthesis of stable radicals relevant to molecular junctions, as well as offering current insight into the electronic properties of radicals in single-molecule devices. By exploring both the chemical and physical properties of established radical systems, we will facilitate increased exploration and development of radical-based molecular systems.
Collapse
Affiliation(s)
- Liang Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Claudia R Prindle
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Wanzhuo Shi
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| |
Collapse
|
17
|
Salthouse R, Hurtado-Gallego J, Grace IM, Davidson R, Alshammari O, Agraït N, Lambert CJ, Bryce MR. Electronic Conductance and Thermopower of Cross-Conjugated and Skipped-Conjugated Molecules in Single-Molecule Junctions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:13751-13758. [PMID: 37528901 PMCID: PMC10389811 DOI: 10.1021/acs.jpcc.3c00742] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 06/21/2023] [Indexed: 08/03/2023]
Abstract
We report a combined experimental and theoretical study of a series of thiomethyl (SMe) anchored cross-conjugated molecules featuring an acyclic central bridging ketone and their analogous skipped-conjugated alcohol derivatives. Studies of these molecules in a gold|single-molecule|gold junction using scanning tunneling microscopy-break junction techniques reveal a similar conductance (G) value for both the cross-conjugated molecules and their skipped-conjugated partners. Theoretical studies based on density functional theory of the molecules in their optimum geometries in the junction reveal the reason for this similarity in conductance, as the predicted conductance for the alcohol series of compounds varies more with the tilt angle. Thermopower measurements reveal a higher Seebeck coefficient (S) for the cross-conjugated ketone molecules relative to the alcohol derivatives, with a particularly high S for the biphenyl derivative 3a (-15.6 μV/K), an increase of threefold compared to its alcohol analog. The predicted behavior of the quantum interference (QI) in this series of cross-conjugated molecules is found to be constructive, though the appearance of a destructive QI feature for 3a is due to the degeneracy of the HOMO orbital and may explain the enhancement of the value of S for this molecule.
Collapse
Affiliation(s)
| | - Juan Hurtado-Gallego
- Departamento
de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Iain M. Grace
- Physics
Department, Lancaster University, Lancaster LA1 4YB, U.K.
| | - Ross Davidson
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| | - Ohud Alshammari
- Physics
Department, Lancaster University, Lancaster LA1 4YB, U.K.
| | - Nicolás Agraït
- Departamento
de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
- Condensed
Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia
de Materiales “Nicolás Cabrera” (INC), Universidad Autónoma de Madrid, Madrid E-28049, Spain
- Instituto
Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, Madrid E-28049, Spain
| | - Colin J. Lambert
- Physics
Department, Lancaster University, Lancaster LA1 4YB, U.K.
| | - Martin R. Bryce
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| |
Collapse
|
18
|
Daaoub A, Morris JMF, Béland VA, Demay‐Drouhard P, Hussein A, Higgins SJ, Sadeghi H, Nichols RJ, Vezzoli A, Baumgartner T, Sangtarash S. Not So Innocent After All: Interfacial Chemistry Determines Charge-Transport Efficiency in Single-Molecule Junctions. Angew Chem Int Ed Engl 2023; 62:e202302150. [PMID: 37029093 PMCID: PMC10953449 DOI: 10.1002/anie.202302150] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/24/2023] [Accepted: 04/06/2023] [Indexed: 04/09/2023]
Abstract
Most studies in molecular electronics focus on altering the molecular wire backbone to tune the electrical properties of the whole junction. However, it is often overlooked that the chemical structure of the groups anchoring the molecule to the metallic electrodes influences the electronic structure of the whole system and, therefore, its conductance. We synthesised electron-accepting dithienophosphole oxide derivatives and fabricated their single-molecule junctions. We found that the anchor group has a dramatic effect on charge-transport efficiency: in our case, electron-deficient 4-pyridyl contacts suppress conductance, while electron-rich 4-thioanisole termini promote efficient transport. Our calculations show that this is due to minute changes in charge distribution, probed at the electrode interface. Our findings provide a framework for efficient molecular junction design, especially valuable for compounds with strong electron withdrawing/donating backbones.
Collapse
Affiliation(s)
- Abdalghani Daaoub
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - James M. F. Morris
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Vanessa A. Béland
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Paul Demay‐Drouhard
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Amaar Hussein
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Hatef Sadeghi
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Andrea Vezzoli
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Thomas Baumgartner
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Sara Sangtarash
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| |
Collapse
|
19
|
Alshammari M, Al-Jobory AA, Alotaibi T, Lambert CJ, Ismael A. Orientational control of molecular scale thermoelectricity. NANOSCALE ADVANCES 2022; 4:4635-4638. [PMID: 36341305 PMCID: PMC9595198 DOI: 10.1039/d2na00515h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/03/2022] [Indexed: 06/13/2023]
Abstract
Through a comprehensive theoretical study, we demonstrate that single-molecule junctions formed from asymmetric molecules with different terminal groups can exhibit Seebeck coefficients, whose sign depends on the orientation of the molecule within the junction. Three anthracene-based molecules are studied, one of which exhibits this bi-thermoelectric behaviour, due to the presence of a thioacetate terminal group at one end and a pyridyl terminal group at the other. A pre-requisite for obtaining this behaviour is the use of junction electrodes formed from different materials. In our case, we use gold as the bottom electrode and graphene-coated gold as the top electrode. This demonstration of bi-thermoelecricity means that if molecules with alternating orientations can be deposited on a substrate, then they form a basis for boosting the thermovoltage in molecular-scale thermoelectric energy generators (TEGs).
Collapse
Affiliation(s)
- Majed Alshammari
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Science, Jouf University Sakaka Saudi Arabia
| | - Alaa A Al-Jobory
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Science, University of Anbar Anbar Iraq
| | - Turki Alotaibi
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Science, Jouf University Sakaka Saudi Arabia
| | - Colin J Lambert
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Ali Ismael
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Education for Pure Science, Tikrit University Tikrit Iraq
| |
Collapse
|
20
|
Bhattacharya R, Maiti SK. Role of inter-electrode coupling on thermoelectricity in an interferometric geometry: a new proposition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:475304. [PMID: 36179701 DOI: 10.1088/1361-648x/ac96bc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
Efficient thermoelectric (TE) energy conversion is one of the most desirable solutions of our current day energy crisis. Exploiting the effect of quantum interference among electronic waves, in this work we propose a prescription of getting high TE efficiency, the so-calledfigure of merit(ZT), considering an interferometric geometry where a loop conductor is clamped between two heat baths. Unlike conventional junction configurations, we introduce an additional path for electron transfer directly from source to drain, due to their close proximity. The interplay between different paths leads to an enhancedZT(ZT > 1). Moreover, the efficiency can be further regulated by tuning the inter-electrode coupling. The effects of magnetic flux threaded by the ring and disorder are also discussed. Our proposed prescription may lead to a new route of designing tunable TE devices at nanoscale level.
Collapse
Affiliation(s)
- Ranjini Bhattacharya
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700108, India
| | - Santanu K Maiti
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700108, India
| |
Collapse
|
21
|
Fallaque JG, Rodríguez-González S, Martín F, Díaz C. Self-energy corrected DFT-NEGF for conductance in molecular junctions: an accurate and efficient implementation for TRANSIESTA package applied to Au electrodes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:435901. [PMID: 35970178 DOI: 10.1088/1361-648x/ac89c4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
In view of the development and the importance that the studies of conductance through molecular junctions is acquiring, robust, reliable and easy-to-use theoretical tools are the most required. Here, we present an efficient implementation of the self-energy correction to density functional theory non-equilibrium Green functions method for TRANSIESTA package. We have assessed the validity of our implementation using as benchmark systems a family of acene complexes with increasing number of aromatic rings and several anchoring groups. Our theoretical results show an excellent agreement with experimentally available measurements assuring the robustness and accuracy of our implementation.
Collapse
Affiliation(s)
- Joel G Fallaque
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Sandra Rodríguez-González
- Departamento de Química Física Aplicada, Módulo 14, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Fernando Martín
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Cristina Díaz
- Departamento de Química Física, Facultad de CC Químicas, Universidad Complutense de Madrid, Madrid, 28040, Spain
| |
Collapse
|
22
|
Tabatabaei F, Merabia S, Gotsmann B, Prunnila M, Niehaus TA. Molecular electronic refrigeration against parallel phonon heat leakage channels. NANOSCALE 2022; 14:11003-11011. [PMID: 35861384 DOI: 10.1039/d2nr00529h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Due to their structured density of states, molecular junctions provide rich resources to filter and control the flow of electrons and phonons. Here we compute the out of equilibrium current-voltage characteristics and dissipated heat of some recently synthesized oligophenylenes (OPE3) using the Density Functional based Tight-Binding (DFTB) method within Non-Equilibrium Green's Function Theory (NEGF). We analyze the Peltier cooling power for these molecular junctions as function of a bias voltage and investigate the parameters that lead to optimal cooling performance. In order to quantify the attainable temperature reduction, an electro-thermal circuit model is presented, in which the key electronic and thermal transport parameters enter. Overall, our results demonstrate that the studied OPE3 devices are compatible with temperature reductions of several K. Based on the results, some strategies to enable high performance devices for cooling applications are briefly discussed.
Collapse
Affiliation(s)
- Fatemeh Tabatabaei
- Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne, France.
| | - Samy Merabia
- Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne, France.
| | | | - Mika Prunnila
- VTT Technical Research Centre of Finland Ltd., Tietotie 3, FI-02150 Espoo, Finland
| | - Thomas A Niehaus
- Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne, France.
| |
Collapse
|
23
|
Wilkinson LA, Bennett TLR, Grace IM, Hamill J, Wang X, Au-Yong S, Ismael A, Jarvis SP, Hou S, Albrecht T, Cohen LF, Lambert C, Robinson BJ, Long NJ. Assembly, structure and thermoelectric properties of 1,1'-dialkynylferrocene 'hinges'. Chem Sci 2022; 13:8380-8387. [PMID: 35919728 PMCID: PMC9297386 DOI: 10.1039/d2sc00861k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 06/24/2022] [Indexed: 11/21/2022] Open
Abstract
Dialkynylferrocenes exhibit attractive electronic and rotational features that make them ideal candidates for use in molecular electronic applications. However previous works have primarily focussed on single-molecule studies, with limited opportunities to translate these features into devices. In this report, we utilise a variety of techniques to examine both the geometric and electronic structure of a range of 1,1'-dialkynylferrocene molecules, as either single-molecules, or as self-assembled monolayers. Previous single molecule studies have shown that similar molecules can adopt an 'open' conformation. However, in this work, DFT calculations, STM-BJ experiments and AFM imaging reveal that these molecules prefer to occupy a 'hairpin' conformation, where both alkynes point towards the metal surface. Interestingly we find that only one of the terminal anchor groups binds to the surface, though both the presence and nature of the second alkyne affect the thermoelectric properties of these systems. First, the secondary alkyne acts to affect the position of the frontier molecular orbitals, leading to increases in the Seebeck coefficient. Secondly, theoretical calculations suggested that rotating the secondary alkyne away from the surface acts to modulate thermoelectric properties. This work represents the first of its kind to examine the assembly of dialkynylferrocenes, providing valuable information about both their structure and electronic properties, as well as unveiling new ways in which both of these properties can be controlled.
Collapse
Affiliation(s)
- Luke A Wilkinson
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
- Department of Chemistry, University of York Heslington York YO10 5DD UK
| | - Troy L R Bennett
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| | - Iain M Grace
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Joseph Hamill
- Department of Chemistry, Birmingham University Edgbaston Birmingham B15 2TT UK
| | - Xintai Wang
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- The Blackett Laboratory, Imperial College London South Kensington Campus London SW7 2AZ UK
| | - Sophie Au-Yong
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Ali Ismael
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Samuel P Jarvis
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Songjun Hou
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Tim Albrecht
- Department of Chemistry, Birmingham University Edgbaston Birmingham B15 2TT UK
| | - Lesley F Cohen
- The Blackett Laboratory, Imperial College London South Kensington Campus London SW7 2AZ UK
| | - Colin Lambert
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | | | - Nicholas J Long
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| |
Collapse
|
24
|
Roemer M, Gillespie A, Jago D, Costa-Milan D, Alqahtani J, Hurtado-Gallego J, Sadeghi H, Lambert CJ, Spackman PR, Sobolev AN, Skelton BW, Grosjean A, Walkey M, Kampmann S, Vezzoli A, Simpson PV, Massi M, Planje I, Rubio-Bollinger G, Agraït N, Higgins SJ, Sangtarash S, Piggott MJ, Nichols RJ, Koutsantonis GA. 2,7- and 4,9-Dialkynyldihydropyrene Molecular Switches: Syntheses, Properties, and Charge Transport in Single-Molecule Junctions. J Am Chem Soc 2022; 144:12698-12714. [PMID: 35767015 DOI: 10.1021/jacs.2c02289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes the syntheses of several functionalized dihydropyrene (DHP) molecular switches with different substitution patterns. Regioselective nucleophilic alkylation of a 5-substituted dimethyl isophthalate allowed the development of a workable synthetic protocol for the preparation of 2,7-alkyne-functionalized DHPs. Synthesis of DHPs with surface-anchoring groups in the 2,7- and 4,9-positions is described. The molecular structures of several intermediates and DHPs were elucidated by X-ray single-crystal diffraction. Molecular properties and switching capabilities of both types of DHPs were assessed by light irradiation experiments, spectroelectrochemistry, and cyclic voltammetry. Spectroelectrochemistry, in combination with density functional theory (DFT) calculations, shows reversible electrochemical switching from the DHP forms to the cyclophanediene (CPD) forms. Charge-transport behavior was assessed in single-molecule scanning tunneling microscope (STM) break junctions, combined with density functional theory-based quantum transport calculations. All DHPs with surface-contacting groups form stable molecular junctions. Experiments show that the molecular conductance depends on the substitution pattern of the DHP motif. The conductance was found to decrease with increasing applied bias.
Collapse
Affiliation(s)
- Max Roemer
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Angus Gillespie
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - David Jago
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - David Costa-Milan
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Jehan Alqahtani
- Department of Physics, King Khalid University, Abha 62529, Saudi Arabia
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Juan Hurtado-Gallego
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Peter R Spackman
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Alexandre N Sobolev
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009, Australia
| | - Brian W Skelton
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009, Australia
| | - Arnaud Grosjean
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Mark Walkey
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Sven Kampmann
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Peter V Simpson
- School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - Inco Planje
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Gabino Rubio-Bollinger
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Nicolás Agraït
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, E-28049 Madrid, Spain
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Matthew J Piggott
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - George A Koutsantonis
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| |
Collapse
|
25
|
Lee W, Louie S, Evans AM, Orchanian NM, Stone IB, Zhang B, Wei Y, Roy X, Nuckolls C, Venkataraman L. Increased Molecular Conductance in Oligo[ n]phenylene Wires by Thermally Enhanced Dihedral Planarization. NANO LETTERS 2022; 22:4919-4924. [PMID: 35640062 DOI: 10.1021/acs.nanolett.2c01549] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Coherent tunneling electron transport through molecular wires has been theoretically established as a temperature-independent process. Although several experimental studies have shown counter examples, robust models to describe this temperature dependence have not been thoroughly developed. Here, we demonstrate that dynamic molecular structures lead to temperature-dependent conductance within coherent tunneling regime. Using a custom-built variable-temperature scanning tunneling microscopy break-junction instrument, we find that oligo[n]phenylenes exhibit clear temperature-dependent conductance. Our calculations reveal that thermally activated dihedral rotations allow these molecular wires to have a higher probability of being in a planar conformation. As the tunneling occurs primarily through π-orbitals, enhanced coplanarization substantially increases the time-averaged tunneling probability. These calculations are consistent with the observation that more rotational pivot points in longer molecular wires leads to larger temperature-dependence on conductance. These findings reveal that molecular conductance within coherent and off-resonant electron transport regimes can be controlled by manipulating dynamic molecular structure.
Collapse
|
26
|
Bennett TLR, Alshammari M, Au-Yong S, Almutlg A, Wang X, Wilkinson LA, Albrecht T, Jarvis SP, Cohen LF, Ismael A, Lambert CJ, Robinson BJ, Long NJ. Multi-component self-assembled molecular-electronic films: towards new high-performance thermoelectric systems. Chem Sci 2022; 13:5176-5185. [PMID: 35655580 PMCID: PMC9093172 DOI: 10.1039/d2sc00078d] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 04/14/2022] [Indexed: 12/02/2022] Open
Abstract
The thermoelectric properties of parallel arrays of organic molecules on a surface offer the potential for large-area, flexible, solution processed, energy harvesting thin-films, whose room-temperature transport properties are controlled by quantum interference (QI). Recently, it has been demonstrated that constructive QI (CQI) can be translated from single molecules to self-assembled monolayers (SAMs), boosting both electrical conductivities and Seebeck coefficients. However, these CQI-enhanced systems are limited by rigid coupling of the component molecules to metallic electrodes, preventing the introduction of additional layers which would be advantageous for their further development. These rigid couplings also limit our ability to suppress the transport of phonons through these systems, which could act to boost their thermoelectric output, without comprising on their impressive electronic features. Here, through a combined experimental and theoretical study, we show that cross-plane thermoelectricity in SAMs can be enhanced by incorporating extra molecular layers. We utilize a bottom-up approach to assemble multi-component thin-films that combine a rigid, highly conductive 'sticky'-linker, formed from alkynyl-functionalised anthracenes, and a 'slippery'-linker consisting of a functionalized metalloporphyrin. Starting from an anthracene-based SAM, we demonstrate that subsequent addition of either a porphyrin layer or a graphene layer increases the Seebeck coefficient, and addition of both porphyrin and graphene leads to a further boost in their Seebeck coefficients. This demonstration of Seebeck-enhanced multi-component SAMs is the first of its kind and presents a new strategy towards the design of thin-film thermoelectric materials.
Collapse
Affiliation(s)
- Troy L R Bennett
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| | - Majed Alshammari
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Science, Jouf University Skaka Saudi Arabia
| | - Sophie Au-Yong
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Ahmad Almutlg
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Mathematics, College of Science, Qassim University Almethnab Saudi Arabia
| | - Xintai Wang
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- The Blackett Laboratory, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Luke A Wilkinson
- Department of Chemistry, University of York Heslington York YO10 5DD UK
| | - Tim Albrecht
- Department of Chemistry, Birmingham University Edgbaston Birmingham B15 2TT UK
| | - Samuel P Jarvis
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | - Lesley F Cohen
- The Blackett Laboratory, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Ali Ismael
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Education for Pure Science, Tikrit University Tikrit Iraq
| | - Colin J Lambert
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | | | - Nicholas J Long
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| |
Collapse
|
27
|
He GC, Shi LN, Hua YL, Zhu XL. The phonon scattering mechanism and its effect on the temperature dependent thermal and thermoelectric properties of a silver nanowire. Phys Chem Chem Phys 2022; 24:3059-3065. [PMID: 35040461 DOI: 10.1039/d1cp04914c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, the electron-phonon, phonon-phonon, and phonon structure scattering mechanisms and their effect on the thermal and thermoelectric properties of a silver nanowire (AgNW) is investigated in the temperature range of 10 to 300 K. The electron-phonon scattering rate decreases with the increase of temperature. The phonon-phonon scattering rate increases with temperature and becomes greater than the electron-phonon scattering rate when the temperature is higher than the Debye temperature (223 K). The rate of phonon structure scattering is constant. The total phonon scattering rate decreases with temperature when the temperature is lower than about 150 K, and increases when the temperature is higher than 150 K. Correspondingly, the temperature dependent variation trend of the lattice thermal conductivity is opposite diametrically to that of the total phonon scattering rate. The thermoelectric properties of the AgNW are strongly coupled with the thermal conductivity via the phonon and electron transition. The thermoelectric properties of the material are quantified by the figure of merit (ZT). The ZT value of the AgNW is greater than that of bulk silver in the corresponding temperature range, and this difference increases with temperature. The order of the ZT of the AgNW is about 13 times greater than that of bulk silver at room temperature. The large increase of the ZT value of the AgNW is mainly due to the enhanced electron scattering and phonon scattering mechanisms in the AgNW.
Collapse
Affiliation(s)
- Gui-Cang He
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China.
| | - Li-Na Shi
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China.
| | - Yi-Lei Hua
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China.
| | - Xiao-Li Zhu
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China.
| |
Collapse
|
28
|
Chen H, Chen Y, Zhang H, Cao W, Fang C, Zhou Y, Xiao Z, Shi J, Chen W, Liu J, Hong W. Quantum interference enhanced thermopower in single-molecule thiophene junctions. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.06.052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
29
|
Xie Z, Diez Cabanes V, Van Nguyen Q, Rodriguez-Gonzalez S, Norel L, Galangau O, Rigaut S, Cornil J, Frisbie CD. Quantifying Image Charge Effects in Molecular Tunnel Junctions Based on Self-Assembled Monolayers of Substituted Oligophenylene Ethynylene Dithiols. ACS APPLIED MATERIALS & INTERFACES 2021; 13:56404-56412. [PMID: 34783518 DOI: 10.1021/acsami.1c16398] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A number of factors contribute to orbital energy alignment with respect to the Fermi level in molecular tunnel junctions. Here, we report a combined experimental and theoretical effort to quantify the effect of metal image potentials on the highest occupied molecular orbital to Fermi level offset, εh, for molecular junctions based on self-assembled monolayers (SAMs) of oligophenylene ethynylene dithiols (OPX) on Au. Our experimental approach involves the use of both transport and photoelectron spectroscopy to extract the offsets, εhtrans and εhUPS, respectively. We take the difference in these quantities to be the image potential energy eVimage. In the theoretical approach, we use density functional theory (DFT) to calculate directly eVimage between positive charge on an OPX molecule and the negative image charge in the Au. Both approaches yield eVimage ∼ -0.1 eV per metal contact, meaning that the total image potential energy is ∼-0.2 eV for an assembled junction with two Au contacts. Thus, we find that the total image potential energy is 25-30% of the total offset εh, which means that image charge effects are significant in OPX junctions. Our methods should be generally applicable to understanding image charge effects as a function of molecular size, for example, in a variety of SAM-based junctions.
Collapse
Affiliation(s)
- Zuoti Xie
- Department of Materials Science and Engineering, Guangdong Technion-Israel Institute of Technology, Shantou, Guangdong 515063, China
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Valentin Diez Cabanes
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons B-7000, Belgium
| | - Quyen Van Nguyen
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Sandra Rodriguez-Gonzalez
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons B-7000, Belgium
- Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, Malaga 29071, Spain
| | - Lucie Norel
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Rennes F-3500, France
| | - Olivier Galangau
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Rennes F-3500, France
| | - Stéphane Rigaut
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Rennes F-3500, France
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons B-7000, Belgium
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
30
|
Li S, Jiang Y, Wang Y, Sanvito S, Hou S. In Situ Tuning of the Charge-Carrier Polarity in Imidazole-Linked Single-Molecule Junctions. J Phys Chem Lett 2021; 12:7596-7604. [PMID: 34347489 DOI: 10.1021/acs.jpclett.1c01996] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Manipulating the nature of the charge carriers at the single-molecule level is one of the major challenges of molecular electronics. Using first-principles quantum transport calculations, we have investigated the electronic transport properties of imidazole-linked single-molecule junctions and identified the hydrogen atom bonded to the pyrrole-like nitrogen in imidazole as a switch to tune the polarity of the charge carriers. Our calculations show that the chemical nature of the imidazole anchors is dramatically altered by dehydrogenation, which changes the dominant charge carriers from electrons to holes. It is also revealed that upon dehydrogenation the interfacial Au-N bonds are modified from donor-acceptor-like to covalent, along with a significant promotion of the low-bias conductance and the junction stability. At variance with other traditional methods that always require drastic modifications of the junction structure, our findings provide a promising approach to tailor in situ the polarity of charge carriers in molecular electronic devices.
Collapse
Affiliation(s)
- Shi Li
- Center for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Yuxuan Jiang
- Center for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Yongfeng Wang
- Center for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Shimin Hou
- Center for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| |
Collapse
|
31
|
O'Driscoll LJ, Bryce MR. A review of oligo(arylene ethynylene) derivatives in molecular junctions. NANOSCALE 2021; 13:10668-10711. [PMID: 34110337 DOI: 10.1039/d1nr02023d] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Oligo(arylene ethynylene) (OAE) derivatives are the "workhorse" molecules of molecular electronics. Their ease of synthesis and flexibility of functionalisation mean that a diverse array of OAE molecular wires have been designed, synthesised and studied theoretically and experimentally in molecular junctions using both single-molecule and ensemble methods. This review summarises the breadth of molecular designs that have been investigated with emphasis on structure-property relationships with respect to the electronic conductance of OAEs. The factors considered include molecular length, connectivity, conjugation, (anti)aromaticity, heteroatom effects and quantum interference (QI). Growing interest in the thermoelectric properties of OAE derivatives, which are expected to be at the forefront of research into organic thermoelectric devices, is also explored.
Collapse
Affiliation(s)
- Luke J O'Driscoll
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, UKDH1 3LE.
| | - Martin R Bryce
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, UKDH1 3LE.
| |
Collapse
|
32
|
Ramezani Akbarabadi S, Rahimpour Soleimani H, Bagheri Tagani M. Side-group-mediated thermoelectric properties of anthracene single-molecule junction with anchoring groups. Sci Rep 2021; 11:8958. [PMID: 33903663 PMCID: PMC8076224 DOI: 10.1038/s41598-021-88297-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/12/2021] [Indexed: 02/02/2023] Open
Abstract
Charge transfer characteristics of single-molecule junctions at the nanoscale, and consequently, their thermoelectric properties can be dramatically tuned by chemical or conformational modification of side groups or anchoring groups. In this study, we used density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) formalism in the linear response regime to examine the thermoelectric properties of a side-group-mediated anthracene molecule coupled to gold (Au) electrodes via anchoring groups. In order to provide a comparative inspection three different side groups, i.e. amine, nitro and methyl, in two different positions were considered for the functionalization of the molecule terminated with thiol or isocyanide anchoring groups. We showed that when the anchored molecule is perturbed with side group, the peaks of the transmission spectrum were shifted relative to the Fermi energy in comparison to the unperturbed molecule (i.e. without side group) leading to modified thermoelectric properties of the system. Particularly, in the thiol-terminated molecule the amine side group showed the greatest figure of merit in both positions which was suppressed by the change of side group position. However, in the isocyanide-terminated molecule the methyl side group attained the greatest thermoelectric efficiency where its magnitude was relatively robust to the change of side group position. In this way, different combinations of side groups and anchoring groups can improve or suppress thermopower and the figure of merit of the molecular junction depending on the interplay between charge donating/accepting nature of the functionals or their position.
Collapse
Affiliation(s)
- Saeideh Ramezani Akbarabadi
- Computational Nanophysics Laboratory (CNL), Department of Physics, University of Guilan, Rasht, 41335-1914, Iran.
| | - Hamid Rahimpour Soleimani
- Computational Nanophysics Laboratory (CNL), Department of Physics, University of Guilan, Rasht, 41335-1914, Iran
| | - Maysam Bagheri Tagani
- Computational Nanophysics Laboratory (CNL), Department of Physics, University of Guilan, Rasht, 41335-1914, Iran
| |
Collapse
|
33
|
Gehring P, Sowa JK, Hsu C, de Bruijckere J, van der Star M, Le Roy JJ, Bogani L, Gauger EM, van der Zant HSJ. Complete mapping of the thermoelectric properties of a single molecule. NATURE NANOTECHNOLOGY 2021; 16:426-430. [PMID: 33649585 DOI: 10.1038/s41565-021-00859-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Theoretical studies suggest that mastering the thermocurrent through single molecules can lead to thermoelectric energy harvesters with unprecedentedly high efficiencies.1-6 This can be achieved by engineering molecule length,7 optimizing the tunnel coupling strength of molecules via chemical anchor groups8 or by creating localized states in the backbone with resulting quantum interference features.4 Empirical verification of these predictions, however, faces considerable experimental challenges and is still awaited. Here we use a novel measurement protocol that simultaneously probes the conductance and thermocurrent flow as a function of bias voltage and gate voltage. We find that the resulting thermocurrent is strongly asymmetric with respect to the gate voltage, with evidence of molecular excited states in the thermocurrent Coulomb diamond maps. These features can be reproduced by a rate-equation model only if it accounts for both the vibrational coupling and the electronic degeneracies, thus giving direct insight into the interplay of electronic and vibrational degrees of freedom, and the role of spin entropy in single molecules. Overall these results show that thermocurrent measurements can be used as a spectroscopic tool to access molecule-specific quantum transport phenomena.
Collapse
Affiliation(s)
- Pascal Gehring
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
- IMCN/NAPS, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
| | - Jakub K Sowa
- Department of Materials, University of Oxford, Oxford, United Kingdom
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Chunwei Hsu
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Joeri de Bruijckere
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Martijn van der Star
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Jennifer J Le Roy
- Department of Materials, University of Oxford, Oxford, United Kingdom
| | - Lapo Bogani
- Department of Materials, University of Oxford, Oxford, United Kingdom
| | - Erik M Gauger
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, UK
| | | |
Collapse
|
34
|
Tan ZB, Laitinen A, Kirsanov NS, Galda A, Vinokur VM, Haque M, Savin A, Golubev DS, Lesovik GB, Hakonen PJ. Thermoelectric current in a graphene Cooper pair splitter. Nat Commun 2021; 12:138. [PMID: 33420055 PMCID: PMC7794233 DOI: 10.1038/s41467-020-20476-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 11/29/2020] [Indexed: 11/17/2022] Open
Abstract
Generation of electric voltage in a conductor by applying a temperature gradient is a fundamental phenomenon called the Seebeck effect. This effect and its inverse is widely exploited in diverse applications ranging from thermoelectric power generators to temperature sensing. Recently, a possibility of thermoelectricity arising from the interplay of the non-local Cooper pair splitting and the elastic co-tunneling in the hybrid normal metal-superconductor-normal metal structures was predicted. Here, we report the observation of the non-local Seebeck effect in a graphene-based Cooper pair splitting device comprising two quantum dots connected to an aluminum superconductor and present a theoretical description of this phenomenon. The observed non-local Seebeck effect offers an efficient tool for producing entangled electrons. Thermoelectricity due to the interplay of the nonlocal Cooper pair splitting and the elastic co-tunneling in normal metal-superconductor-normal metal structure is predicted. Here, the authors observe the non-local Seebeck effect in a graphene-based Cooper pair splitting device.
Collapse
Affiliation(s)
- Z B Tan
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.,Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - A Laitinen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - N S Kirsanov
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.,Terra Quantum AG, St. Gallerstrasse 16A, 9400, Rorschach, Switzerland.,Moscow Institute of Physics and Technology, Institutskii Per. 9, Dolgoprudny, Moscow Distr., 141700, Russian Federation.,Consortium for Advanced Science and Engineering (CASE), University of Chicago, 5801 S Ellis Avenue, Chicago, IL, 60637, USA
| | - A Galda
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.,Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL, 60439, USA
| | - V M Vinokur
- Consortium for Advanced Science and Engineering (CASE), University of Chicago, 5801 S Ellis Avenue, Chicago, IL, 60637, USA.,Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL, 60439, USA
| | - M Haque
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - A Savin
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - D S Golubev
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | - G B Lesovik
- Terra Quantum AG, St. Gallerstrasse 16A, 9400, Rorschach, Switzerland.,Moscow Institute of Physics and Technology, Institutskii Per. 9, Dolgoprudny, Moscow Distr., 141700, Russian Federation
| | - P J Hakonen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland. .,QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland.
| |
Collapse
|
35
|
Delmas V, Diez-Cabanes V, van Dyck C, Scheer E, Costuas K, Cornil J. On the reliability of acquiring molecular junction parameters by Lorentzian fitting of I/ V curves. Phys Chem Chem Phys 2020; 22:26702-26706. [PMID: 33216107 DOI: 10.1039/d0cp05372d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Fitting the I/V curves of molecular junctions by simple analytical models is often done to extract relevant molecular parameters such as energy level alignment or interfacial electronic coupling to build up useful property-relationships. However, such models can suffer from severe limitations and hence provide unreliable molecular parameters. This is illustrated here by extracting key molecular parameters by fitting computed voltage-dependent transmission spectra and by comparing them to the values obtained by fitting the calculated I/V curves with a typical Lorentzian model used in the literature. Doing so, we observe a large discrepancy between the two sets of values which warns us about the risks of using simple fitting expressions. Interestingly, we demonstrate that the quality of the fit can be improved by imposing the low bias conductance and Seebeck coefficient of the junction to be recovered in the fitting procedure.
Collapse
Affiliation(s)
- Vincent Delmas
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
| | | | | | | | | | | |
Collapse
|
36
|
Kobayashi S, Kaneko S, Kiguchi M, Tsukagoshi K, Nishino T. Tolerance to Stretching in Thiol-Terminated Single-Molecule Junctions Characterized by Surface-Enhanced Raman Scattering. J Phys Chem Lett 2020; 11:6712-6717. [PMID: 32619093 DOI: 10.1021/acs.jpclett.0c01526] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigated the change in the metal-molecule interaction in a 1,4-benzenedithiol (BDT) single-molecule junction using a combination of surface-enhanced Raman scattering spectra and current-voltage curves. During the stretching process, the conductance of the junction systematically decreased, accompanied by an increase in the vibrational energy of the CC stretching mode. By analyzing the current-voltage curves and Raman spectra, we found that the interaction between the π orbital of BDT and the electronic states of Au was diminished by the orientation change of BDT during the stretching process. A comparison with a 4,4'-bipyridine single-molecule junction revealed that the reduction of coupling of the Au-S contacts was smaller than that of Au-pyridine contacts. Therefore, the electronic states originating from the contact geometry are responsible for the tolerance to the stretching of thiol-terminated molecular junctions.
Collapse
Affiliation(s)
- S Kobayashi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | - S Kaneko
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
- JST PRESTO, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
| | - M Kiguchi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | - K Tsukagoshi
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Tsukuba, Ibaraki 305-0044, Japan
| | - T Nishino
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| |
Collapse
|
37
|
Chen H, Sangtarash S, Li G, Gantenbein M, Cao W, Alqorashi A, Liu J, Zhang C, Zhang Y, Chen L, Chen Y, Olsen G, Sadeghi H, Bryce MR, Lambert CJ, Hong W. Exploring the thermoelectric properties of oligo(phenylene-ethynylene) derivatives. NANOSCALE 2020; 12:15150-15156. [PMID: 32658229 DOI: 10.1039/d0nr03303k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Seebeck coefficient measurements provide unique insights into the electronic structure of single-molecule junctions, which underpins their charge and heat transport properties. Since the Seebeck coefficient depends on the slope of the transmission function at the Fermi energy (EF), the sign of the thermoelectric voltage will be determined by the location of the molecular orbital levels relative to EF. Here we investigate thermoelectricity in molecular junctions formed from a series of oligophenylene-ethynylene (OPE) derivatives with biphenylene, naphthalene and anthracene cores and pyridyl or methylthio end-groups. Single-molecule conductance and thermoelectric voltage data were obtained using a home-built scanning tunneling microscope break junction technique. The results show that all the OPE derivatives studied here are dominated by the lowest unoccupied molecular orbital level. The Seebeck coefficients for these molecules follow the same trend as the energy derivatives of their corresponding transmission spectra around the Fermi level. The molecule terminated with pyridyl units has the largest Seebeck coefficient corresponding to the highest slope of the transmission function at EF. Density-functional-theory-based quantum transport calculations support the experimental results.
Collapse
Affiliation(s)
- Hang Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | - Sara Sangtarash
- Department of Physics, Lancaster University, LA1 4YB, Lancaster, UK. and School of Engineering, University of Warwick, Coventry CV4 7AL, UK
| | - Guopeng Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | | | - Wenqiang Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | - Afaf Alqorashi
- Department of Physics, Lancaster University, LA1 4YB, Lancaster, UK.
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | - Chunquan Zhang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Yulong Zhang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Lijue Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | - Yaorong Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| | - Gunnar Olsen
- Department of Chemistry, Durham University, DH1 3LE, Durham, UK.
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry CV4 7AL, UK
| | - Martin R Bryce
- Department of Chemistry, Durham University, DH1 3LE, Durham, UK.
| | - Colin J Lambert
- Department of Physics, Lancaster University, LA1 4YB, Lancaster, UK.
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, iChEM, Xiamen University, 361005, Xiamen, China.
| |
Collapse
|
38
|
Grace IM, Olsen G, Hurtado-Gallego J, Rincón-García L, Rubio-Bollinger G, Bryce MR, Agraït N, Lambert CJ. Connectivity dependent thermopower of bridged biphenyl molecules in single-molecule junctions. NANOSCALE 2020; 12:14682-14688. [PMID: 32618309 DOI: 10.1039/d0nr04001k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report measurements on gold|single-molecule|gold junctions, using a modified scanning tunneling microscope-break junction (STM-BJ) technique, of the Seebeck coefficient and electrical conductance of a series of bridged biphenyl molecules, with meta connectivities to pyridyl anchor groups. These data are compared with a previously reported study of para-connected analogues. In agreement with a tight binding model, the electrical conductance of the meta series is relatively low and is sensitive to the nature of the bridging groups, whereas in the para case the conductance is higher and relatively insensitive to the presence of the bridging groups. This difference in sensitivity arises from the presence of destructive quantum interference in the π system of the unbridged aromatic core, which is alleviated to different degrees by the presence of bridging groups. More precisely, the Seebeck coefficient of meta-connected molecules was found to vary between -6.1 μV K-1 and -14.1 μV K-1, whereas that of the para-connected molecules varied from -5.5 μV K-1 and -9.0 μV K-1.
Collapse
Affiliation(s)
- Iain M Grace
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Ismael A, Wang X, Bennett TLR, Wilkinson LA, Robinson BJ, Long NJ, Cohen LF, Lambert CJ. Tuning the thermoelectrical properties of anthracene-based self-assembled monolayers. Chem Sci 2020; 11:6836-6841. [PMID: 33033599 PMCID: PMC7504895 DOI: 10.1039/d0sc02193h] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/15/2020] [Indexed: 11/25/2022] Open
Abstract
It is known that the electrical conductance of single molecules can be controlled in a deterministic manner by chemically varying their anchor groups to external electrodes. Here, by employing synthetic methodologies to vary the terminal anchor groups around aromatic anthracene cores, and by forming self-assembled monolayers (SAMs) of the resulting molecules, we demonstrate that this method of control can be translated into cross-plane SAM-on-gold molecular films. The cross-plane conductance of SAMs formed from anthracene-based molecules with four different combinations of anchors are measured to differ by a factor of approximately 3 in agreement with theoretical predictions. We also demonstrate that the Seebeck coefficient of such films can be boosted by more than an order of magnitude by an appropriate choice of anchor groups and that both positive and negative Seebeck coefficients can be realised. This demonstration that the thermoelectric properties of SAMs are controlled by their anchor groups represents a critical step towards functional ultra-thin-film devices for future molecular-scale electronics.
Collapse
Affiliation(s)
- Ali Ismael
- Physics Department , Lancaster University , Lancaster , LA1 4YB , UK . ;
- Department of Physics , College of Education for Pure Science , Tikrit University , Tikrit , Iraq .
| | - Xintai Wang
- Physics Department , Lancaster University , Lancaster , LA1 4YB , UK . ;
- The Blackett Laboratory , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK .
| | - Troy L R Bennett
- Department of Chemistry , Imperial College London , MSRH , White City , London , W12 0BZ , UK .
| | - Luke A Wilkinson
- Department of Chemistry , Imperial College London , MSRH , White City , London , W12 0BZ , UK .
| | | | - Nicholas J Long
- Department of Chemistry , Imperial College London , MSRH , White City , London , W12 0BZ , UK .
| | - Lesley F Cohen
- The Blackett Laboratory , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK .
| | - Colin J Lambert
- Physics Department , Lancaster University , Lancaster , LA1 4YB , UK . ;
| |
Collapse
|
40
|
Ismael AK, Lambert CJ. Molecular-scale thermoelectricity: a worst-case scenario. NANOSCALE HORIZONS 2020; 5:1073-1080. [PMID: 32432630 DOI: 10.1039/d0nh00164c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This article highlights a novel strategy for designing molecules with high thermoelectric performance, which are resilient to fluctuations. In laboratory measurements of thermoelectric properties of single-molecule junctions and self-assembled monolayers, fluctuations in frontier orbital energies relative to the Fermi energy EF of electrodes are an important factor, which determine average values of transport coefficients, such as the average Seebeck coefficient 〈S〉. In a worst-case scenario, where the relative value of EF fluctuates uniformly over the HOMO-LUMO gap, a "worst-case scenario theorem" tells us that the average Seebeck coefficient will vanish unless the transmission coefficient at the LUMO and HOMO resonances take different values. This implies that junction asymmetry is a necessary condition for obtaining non-zero values of 〈S〉 in the presence of large fluctuations. This conclusion that asymmetry can drive high thermoelectric performance is supported by detailed simulations on 17 molecules using density functional theory. Importantly, junction asymmetry does not imply that the molecules themselves should be asymmetric. We demonstrate that symmetric molecules possessing a localised frontier orbital can achieve even higher thermoelectric performance than asymmetric molecules, because under laboratory conditions of slight symmetry breaking, such orbitals are 'silent' and do not contribute to transport. Consequently, transport is biased towards the nearest "non-silent" frontier orbital and leads to a high ensemble averaged Seebeck coefficient. This effect is demonstrated for a spatially-symmetric 1,2,3-triazole-based molecule, a rotaxane-hexayne macrocycle and a phthalocyanine.
Collapse
Affiliation(s)
- Ali K Ismael
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
| | | |
Collapse
|
41
|
Liu B, Yokota K, Komoto Y, Tsutsui M, Taniguchi M. Thermally activated charge transport in carbon atom chains. NANOSCALE 2020; 12:11001-11007. [PMID: 32270842 DOI: 10.1039/d0nr01827a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Charge transport through single molecules is at the heart of molecular electronics for realizing the practical use of the rich quantum characteristics of electrode-molecule-electrode systems. Despite the extensive studies reported in the past, little experimental efforts have been focused on the electron transport mechanism at a temperature higher than the ambient temperature. In this work, we have reported the observation of the subtle interplay between electron tunneling and charge hopping in carbon chains connected to two Au electrodes at elevated temperatures. We measured the single-molecule conductance of Au-alkanedithiol-Au molecular junctions at various temperatures from 300 K to 420 K in vacuum. The temperature dependence of conductance suggested substantial roles of superexchange with inter-chain charge hopping under elevated temperatures for alkane chains longer than heptane. This finding provides a guide to design functional molecular junctions under practical conditions.
Collapse
Affiliation(s)
- Bo Liu
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan
| | - Yuki Komoto
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
| |
Collapse
|
42
|
Fu T, Zang Y, Zou Q, Nuckolls C, Venkataraman L. Using Deep Learning to Identify Molecular Junction Characteristics. NANO LETTERS 2020; 20:3320-3325. [PMID: 32242671 DOI: 10.1021/acs.nanolett.0c00198] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The scanning tunneling microscope-based break junction (STM-BJ) is used widely to create and characterize single metal-molecule-metal junctions. In this technique, conductance is continuously recorded as a metal point contact is broken in a solution of molecules. Conductance plateaus are seen when stable molecular junctions are formed. Typically, thousands of junctions are created and measured, yielding thousands of distinct conductance versus extension traces. However, such traces are rarely analyzed individually to recognize the types of junctions formed. Here, we present a deep learning-based method to identify molecular junctions and show that it performs better than several commonly used and recently reported techniques. We demonstrate molecular junction identification from mixed solution measurements with accuracies as high as 97%. We also apply this model to an in situ electric field-driven isomerization reaction of a [3]cumulene to follow the reaction over time. Furthermore, we demonstrate that our model can remain accurate even when a key parameter, the average junction conductance, is eliminated from the analysis, showing that our model goes beyond conventional analysis in existing methods.
Collapse
Affiliation(s)
- Tianren Fu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yaping Zang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Qi Zou
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| |
Collapse
|
43
|
Zhao ZH, Wang L, Li S, Zhang WD, He G, Wang D, Hou SM, Wan LJ. Single-Molecule Conductance through an Isoelectronic B–N Substituted Phenanthrene Junction. J Am Chem Soc 2020; 142:8068-8073. [DOI: 10.1021/jacs.0c00879] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhi-Hao Zhao
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Science (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lin Wang
- School of Materials Science and Technology, University of Geosciences, Beijing 100083, China
| | - Shi Li
- Key Laboratory for Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
| | - Wei-Dong Zhang
- Frontier Institute of Science and Technology, State Key Laboratory for Strength and Vibration of Mechanical Structures, Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi 710054, China
| | - Gang He
- Frontier Institute of Science and Technology, State Key Laboratory for Strength and Vibration of Mechanical Structures, Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi 710054, China
| | - Dong Wang
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Science (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shi-Min Hou
- Key Laboratory for Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
| | - Li-Jun Wan
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Science (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
44
|
Cohen G, Galperin M. Green’s function methods for single molecule junctions. J Chem Phys 2020; 152:090901. [DOI: 10.1063/1.5145210] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Guy Cohen
- The Raymond and Beverley Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
- School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michael Galperin
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
| |
Collapse
|
45
|
Bâldea I. Evidence That Molecules in Molecular Junctions May Not Be Subject to the Entire External Perturbation Applied to Electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1329-1337. [PMID: 31957453 DOI: 10.1021/acs.langmuir.9b03430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Whether molecules forming molecular junctions are really subject to the entire external perturbation applied to electrodes is an important issue, but so far, it has not received adequate consideration in the literature. In this paper, we demonstrate that, out of the temperature difference ΔTelectr between electrodes applied in thermopower measurements, molecules only feel a significantly smaller temperature difference (ΔTmolec < ΔTelectr). Rephrasing, temperature drops at metal-molecule interfaces are substantial. Our theoretical analysis to address this problem of fundamental importance for surface science is based on experimental data collected via ultraviolet photoelectron spectroscopy, transition voltage spectroscopy, and Seebeck coefficient measurements. An important practical consequence of the presently reported finding is that the energetic alignment of the frontier molecular orbital (HOMO or LUMO) of the embedded molecules with respect to the metallic Fermi level position deduced from thermopower data-and this is frequently the case in current studies of molecular electronics-is substantially overestimated. Another important result presented here is that, unlike the exponential length dependence characterizing electric conduction (which is a fingerprint for quantum tunneling), thermal conduction through the molecules considered (oligophenylene thiols and alkane thiols) exhibits a length dependence compatible with classical physics.
Collapse
Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie , Universität Heidelberg , Im Neuenheimer Feld 229 , D-69120 Heidelberg , Germany
| |
Collapse
|
46
|
Perrin ML, Eelkema R, Thijssen J, Grozema FC, van der Zant HSJ. Single-molecule functionality in electronic components based on orbital resonances. Phys Chem Chem Phys 2020; 22:12849-12866. [DOI: 10.1039/d0cp01448f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A gateable single-molecule diode and resonant tunneling diode are realized using molecular orbital engineering in multi-site molecules.
Collapse
Affiliation(s)
- Mickael L. Perrin
- Kavli Institute of Nanoscience
- Delft University of Technology
- 2628 CJ Delft
- The Netherlands
- Swiss Federal Laboratories for Materials Science and Technology
| | - Rienk Eelkema
- Department of Chemical Engineering
- Delft University of Technology
- 2629 HZ Delft
- The Netherlands
| | - Jos Thijssen
- Kavli Institute of Nanoscience
- Delft University of Technology
- 2628 CJ Delft
- The Netherlands
| | - Ferdinand C. Grozema
- Department of Chemical Engineering
- Delft University of Technology
- 2629 HZ Delft
- The Netherlands
| | | |
Collapse
|
47
|
Huang M, Dong J, Wang Z, Li Y, Yu L, Liu Y, Qian G, Chang S. Revealing the electronic structure of organic emitting semiconductors at the single-molecule level. Chem Commun (Camb) 2020; 56:14789-14792. [DOI: 10.1039/d0cc05602b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Single-molecule conductance measurements of OLED molecules show that the holes injected from metal electrode can be suppressed by adding electron-withdrawing arms, benefiting the electron–hole balance of OLED devices whose holes are excessive.
Collapse
Affiliation(s)
- Mingzhu Huang
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Jianqiao Dong
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Zhiye Wang
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Yunchuan Li
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Lei Yu
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Yichong Liu
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Gongming Qian
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| | - Shuai Chang
- The State Key Laboratory of Refractories and Metallurgy, and Institute of Advanced Materials and Nanotechnology
- Wuhan University of Science and Technology
- Wuhan 430081
- China
| |
Collapse
|
48
|
SnPc Molecules on Surfaces Studied by Scanning Tunneling Microscopy. J CLUST SCI 2019. [DOI: 10.1007/s10876-019-01610-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
49
|
Tuerhong R, Boero M, Bucher JP. Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:1243-1250. [PMID: 31293862 PMCID: PMC6604733 DOI: 10.3762/bjnano.10.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/06/2019] [Indexed: 06/09/2023]
Abstract
The vibrational excitation related transport properties of a manganese phthalocyanine molecule suspended between the tip of a scanning tunneling microsope (STM) and a surface are investigated by combining the local manipulation capabilities of the STM with inelastic electron tunneling spectroscopy. By attachment of the molecule to the probe tip, the intrinsic physical properties similar to those exhibited by a free standing molecule become accessible. This technique allows one to study locally the magnetic properties, as well as other elementary excitations and their mutual interaction. In particular a clear correlation is observed between the Kondo resonance and the vibrations with a strong incidence of the Kondo correlation on the thermopower measured across the single-molecule junction.
Collapse
Affiliation(s)
| | - Mauro Boero
- Université de Strasbourg, IPCMS UMR 70504, 67034 Strasbourg, France
| | | |
Collapse
|
50
|
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: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [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.
Collapse
|