1
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Ajeel FN, Ahmed AB. Effect of ZnO dimers on the thermoelectric performance of armchair graphene nanoribbons. J Mol Model 2023; 29:145. [PMID: 37067639 DOI: 10.1007/s00894-023-05545-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/03/2023] [Indexed: 04/18/2023]
Abstract
Enhancing the thermoelectric performance in engineered graphene nanoribbons is used to produce thermoelectric nanodevices, which are important in many applications. By using a chemical doping method, armchair graphene nanoribbons (AGNRs) can have thermoelectric properties that are tunable. We predicted that changing the number and geometrical pattern of zinc oxide (ZnO) dimers in an AGNR can engineer thermoelectric properties, so we used density functional-based tight binding (DFTB) combined with the non-equilibrium Green's function (NEGF) to investigate the geometric, electronic, and thermoelectric properties of the AGNR with and without various dopants of ZnO dimers. With three forms of ZnO dimers, ortho, meta, and para dimers, different concentration ratios of Zn and O atoms are used. Our results indicate that the electronic features of AGNR are influenced not only by the concentrations of ZnO dimers but also by the geometrical pattern of ZnO dimers in the AGNR. These results are helpful in better understanding the effect of chemical doping on the transport properties of AGNRs and in motivating nanodevices to improve their thermoelectric performance.
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Affiliation(s)
- Fouad N Ajeel
- Department of Physic, College of Science, University of Sfax, Sfax, Tunisia.
- Department of Physics, College of Science, University of Sumer, Al-Rifai, Iraq.
| | - Ali Ben Ahmed
- Department of Physic, College of Science, University of Sfax, Sfax, Tunisia
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2
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Almeida PA, Martins GB. Thermoelectric transport properties of armchair graphene nanoribbon heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:335302. [PMID: 35675807 DOI: 10.1088/1361-648x/ac76fc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
In this paper, we numerically analyze the thermoelectric (TE) properties of recently synthesized graphene nanoribbon (GNR) heterostructures that are obtained as extensions of pristine armchair graphene nanoribbons (AGNRs). After simulating their band structure through a nearest-neighbor tight-binding model, we use the Landauer formalism to calculate the necessary TE coefficients, with which we obtain the electrical conductanceG, thermopowerS, thermal conductanceKe, linear-response thermocurrentIth/ΔT=GS, and figure of meritZT(using literature results for the phonon thermal conductanceKph), at room temperature. We then compare the results for the nanoribbon heterostructures with those for the pristine AGNR nanoribbons. The comparison shows that the metallic AGNRs become semiconducting (with much higherZTvalues) after the inclusion of the extensions that transform them into heterostructures and that some heterostructures have higher values ofZTwhen compared to the semiconducting pristine AGNRs from which they have originated.
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Affiliation(s)
- P A Almeida
- Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais 38400-902, Brazil
| | - G B Martins
- Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais 38400-902, Brazil
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3
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Singh D, Ahuja R. Dimensionality effects in high‐performance thermoelectric materials: Computational and experimental progress in energy harvesting applications. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1547] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Deobrat Singh
- Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy Uppsala University Uppsala Sweden
| | - Rajeev Ahuja
- Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy Uppsala University Uppsala Sweden
- Department of Physics Indian Institute of Technology Ropar Rupnagar Punjab India
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4
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Gholami Z, Khoeini F. Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures. Sci Rep 2021; 11:15320. [PMID: 34321550 PMCID: PMC8319332 DOI: 10.1038/s41598-021-94842-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023] Open
Abstract
The main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Green's function (NEGF) approach. To further study the thermoelectric (TE) properties of the GSNRs, three defect arrangements of divacancies (DVs) are also considered for a larger system, and their responses are re-evaluated. The results demonstrate that the defected GSNRs with the DVs can provide an almost perfect thermal spin filtering effect (SFE), and spin switching. A negative differential thermoelectric resistance (NDTR) effect and high spin polarization efficiency (SPE) larger than 99.99% are obtained. The system with the DV defects can show a large spin-dependent Seebeck coefficient, equal to Ss ⁓ 1.2 mV/K, which is relatively large and acceptable. Appropriate thermal and electronic properties of the GSNRs can also be obtained by tuning up the DV orientation in the device region. Accordingly, the step-like GSNRs can be employed to produce high efficiency spin caloritronic devices with various features in practical applications.
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Affiliation(s)
- Zainab Gholami
- grid.412673.50000 0004 0382 4160Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
| | - Farhad Khoeini
- grid.412673.50000 0004 0382 4160Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
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5
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Mijbil ZY. Single-molecule thermoelectric properties susceptibility to environment molecules. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1946055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Zainelabideen Yousif Mijbil
- Chemistry and Physiology Department, Veterinary Medicine College, Al-Qasim Green University, Al-Qasim Town, Iraq
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6
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Exploitation of Baird Aromaticity and Clar’s Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons. CHEMISTRY 2021. [DOI: 10.3390/chemistry3020038] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four biphenylene-derived PAHs finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). The results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.
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7
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Ramezani Akbarabadi S, Rahimpour Soleimani H, Golsanamlou Z, Bagheri Tagani M. Enhanced thermoelectric properties in anthracene molecular device with graphene electrodes: the role of phononic thermal conductance. Sci Rep 2020; 10:10922. [PMID: 32616835 PMCID: PMC7331582 DOI: 10.1038/s41598-020-67964-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/17/2020] [Indexed: 11/09/2022] Open
Abstract
Density functional theory (DFT) and the non-equilibrium Green's function (NEGF) formalism in the linear response regime were employed to investigate the impact of doping on the electronic and phononic transport properties in an anthracene molecule attached to two metallic zigzag graphene nanoribbons (ZGNRs). Boron (B) and nitrogen (N) atoms were used for doping and co-doping (NB) of carbon atoms located at the edge of the anthracene molecule. Our results show that B doping enhances the electronic transport in comparison with the other dopants which is due to its ability to increase the binding energy of the system. The chemical doping of the anthracene molecule mainly impacts on the thermopower which results in a significantly enhanced electronic contribution of the figure of merit. On the contrary, considering the effect of phononic thermal conductance suppresses the figure of merit. However, by taking into account the effect of both electron and phonon contributions to the thermal conductance, we find that the thermoelectric efficiency can be improved by B doping. The potential role of the phononic thermal conductance in shaping the thermoelectric properties of molecular junctions has been ignored in numerous studies, however, our findings demonstrate its importance for a realistic and accurate estimation of the thermoelectric figure of merit.
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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
| | - Zahra Golsanamlou
- 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
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8
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Núñez C, Saiz-Bretín M, Orellana PA, Rosales L, Domínguez-Adame F. Tuning the thermoelectric response of silicene nanoribbons with vacancies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:275301. [PMID: 32155600 DOI: 10.1088/1361-648x/ab7e56] [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
In this work, we present a thorough study of the thermoelectric properties of silicene nanoribbons in the presence of a random distribution of atomic vacancies. By using a linear approach within the Landauer formalism, we calculate phonon and electron thermal conductances, the electric conductance, the Seebeck coefficient and the figure of merit of the nanoribbons. We found a sizable reduction of the phonon thermal conductance as a function of the vacancy concentration over a wide range of temperature. At the same time, the electric properties are not severely deteriorated, leading to an overall remarkable thermoelectric efficiency. We conclude that the incorporation of vacancies paves the way for designing better and more efficient nanoscale thermoelectric devices.
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Affiliation(s)
- C Núñez
- Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110 V, Valparaíso, Chile
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9
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A Comprehensive Review of Strategies and Approaches for Enhancing the Performance of Thermoelectric Module. ENERGIES 2020. [DOI: 10.3390/en13123142] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In recent years, thermoelectric (TE) technology has been emerging as a promising alternative and environmentally friendly technology for power generators or cooling devices due to the increasingly serious energy shortage and environmental pollution problems. However, although TE technology has been found for a long time and applied in many professional fields, its low energy conversion efficiency and high cost also hinder its wide application. Thus, it is still urgent to improve the thermoelectric modules. This work comprehensively reviews the status of strategies and approaches for enhancing the performance of thermoelectrics, including material development, structure and geometry improvement, the optimization of a thermal management system, and the thermal structure design. In particular, the influence of contact thermal resistance and the improved optimization methods are discussed. This work covers many fields related to the enhancement of thermoelectrics. It is found that the main challenge of TE technology remains the improvement of materials’ properties, the decrease in costs and commercialization. Therefore, a lot of research needs to be carried out to overcome this challenge and further improve the performance of TE modules. Finally, the future research direction of TE technology is discussed. These discussions provide some practical guidance for the improvement of thermoelectric performance and the promotion of thermoelectric applications.
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10
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Alam MW, Souayeh B, Islam SF. Enhancement of thermoelectric performance of a nanoribbon made ofα-T3lattice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:485303. [PMID: 31489844 DOI: 10.1088/1361-648x/ab3bf6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/16/2019] [Indexed: 05/06/2023]
Abstract
We present electronic and transport properties of a zigzag nanoribbon made oflattice. Our particular focus is on the effects of the continuous evolution of the edge modes (from flat to dispersive) on the thermoelectric transport properties. Unlike the case of graphene nanoribbon, the zigzag nanoribbon oflattice can host a pair of dispersive edge modes at the two valleys for specific width of the ribbon. Moreover, gap opening can also occur at the two valleys depending on the width. The slope of the dispersive edge modes and the energy gap strongly depend on the relative strength of two kinds of hoping parameters present in the system. We compute corresponding transport coefficients such as conductance, thermopower, thermal conductance and the thermoelectric figure of merits by using the tight-binding Green function formalism, in order to explore the roles of the dispersive edge modes. It is found that the thermopower and thermoelectric figure of merits can be enhanced significantly by suitably controlling the edge modes. The figure of merits can be enhanced by thirty times under suitable parameter regime in comparison to the case of graphene. Finally, we reveal that the presence of line defect, close to the edge, can cause a significant impact on the edge modes as well as on electrical conductance and thermopower.
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Affiliation(s)
- Mir Waqas Alam
- Department of Physics, College of Science, King Faisal University, Al-Hassa 31982, PO Box 400, Saudi Arabia
| | - Basma Souayeh
- Department of Physics, College of Science, King Faisal University, Al-Hassa 31982, PO Box 400, Saudi Arabia
| | - Sk Firoz Islam
- Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005, India
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11
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Designing a highly efficient graphene quantum spin heat engine. Sci Rep 2019; 9:6018. [PMID: 30979964 PMCID: PMC6461677 DOI: 10.1038/s41598-019-42279-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/28/2019] [Indexed: 11/10/2022] Open
Abstract
We design a quantum spin heat engine using spin polarized ballistic modes generated in a strained graphene monolayer doped with a magnetic impurity. We observe remarkably large efficiency and large thermoelectric figure of merit both for the charge as well as spin variants of the quantum heat engine. This suggests the use of this device as a highly efficient quantum heat engine for charge as well as spin based transport. Further, a comparison is drawn between the device characteristics of a graphene spin heat engine against a quantum spin Hall heat engine. The reason being edge modes because of their origin should give much better performance. In this respect we observe our graphene based spin heat engine can almost match the performance characteristics of a quantum spin Hall heat engine. Finally, we show that a pure spin current can be transported in our device in absence of any charge current.
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12
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Wu Q, Sadeghi H, Lambert CJ. MoS 2 nano flakes with self-adaptive contacts for efficient thermoelectric energy harvesting. NANOSCALE 2018; 10:7575-7580. [PMID: 29637971 DOI: 10.1039/c8nr01635f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We examine the potential of the low-dimensional material MoS2 for the efficient conversion of waste heat to electricity via the Seebeck effect. Recently monolayer MoS2 nano flakes with self-adaptive Mo6S6 contacts were formed, which take advantage of mechanical stability and chemical covalent bonding to the MoS2. Here, we study the thermoelectric properties of these junctions by calculating their conductance, thermopower and thermal conductance due to both electrons and phonons. We show that thermoelectric figures of merit ZT as high as ∼2.8 are accessible in these junctions, independent of the flake size and shape, provided the Fermi energy is close to a band edge. We show that Nb dopants as substituents for Mo atoms can be used to tune the Fermi energy, and despite the associated inhomogeneous broadening, room temperature values as high as ZT ∼ 0.6 are accessible, increasing to 0.8 at 500 K.
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Affiliation(s)
- Qingqing Wu
- Quantum Technology Centre, Physics Department, Lancaster University, LA1 4YB Lancaster, UK.
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13
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Mani A, Benjamin C. Strained-graphene-based highly efficient quantum heat engine operating at maximum power. Phys Rev E 2018; 96:032118. [PMID: 29346913 DOI: 10.1103/physreve.96.032118] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Indexed: 11/07/2022]
Abstract
A strained graphene monolayer is shown to operate as a highly efficient quantum heat engine delivering maximum power. The efficiency and power of the proposed device exceeds that of recent proposals. The reason for these excellent characteristics is that strain enables complete valley separation in transmittance through the device, implying that increasing strain leads to very high Seebeck coefficient as well as lower conductance. In addition, since time-reversal symmetry is unbroken in our system, the proposed strained graphene quantum heat engine can also act as a high-performance refrigerator.
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Affiliation(s)
- Arjun Mani
- School of Physical Sciences, National Institute of Science Education & Research, HBNI, Jatni-752050, India
| | - Colin Benjamin
- School of Physical Sciences, National Institute of Science Education & Research, HBNI, Jatni-752050, India
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14
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Badehian HA, Gharbavi K. Phonon and thermoelectric properties of single- and double-walled carbon nanotubes from first principles. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2017.1413713] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Wu Q, Sadeghi H, García-Suárez VM, Ferrer J, Lambert CJ. Thermoelectricity in vertical graphene-C 60-graphene architectures. Sci Rep 2017; 7:11680. [PMID: 28916809 PMCID: PMC5601468 DOI: 10.1038/s41598-017-10938-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022] Open
Abstract
Recent studies of single-molecule thermoelectricity have identified families of high-performance molecules. However, in order to translate this discovery into practical thin-film energy-harvesting devices, there is a need for an understanding of the fundamental issues arising when such junctions are placed in parallel. This is relevant because controlled scalability might be used to boost electrical and thermoelectric performance over the current single-junction paradigm. As a first step in this direction, we investigate here the properties of two C60 molecules placed in parallel and sandwiched between top and bottom graphene electrodes. In contrast with classical conductors, we find that increasing the number of parallel junctions from one to two can cause the electrical conductance to increase by more than a factor of 2. Furthermore, we show that the Seebeck coefficient is sensitive to the number of parallel molecules sandwiched between the electrodes, whereas classically it should be unchanged. This non-classical behaviour of the electrical conductance and Seebeck coefficient are due to inter-junction quantum interference, mediated by the electrodes, which leads to an enhanced response in these vertical molecular devices.
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Affiliation(s)
- Qingqing Wu
- Quantum Technology Centre, Lancaster University, LA1 4YB, Lancaster, United Kingdom
| | - Hatef Sadeghi
- Quantum Technology Centre, Lancaster University, LA1 4YB, Lancaster, United Kingdom.
| | - Víctor M García-Suárez
- Departamento de Física, Universidad de Oviedo, 33007, Oviedo, Spain.,Nanomaterials and Nanotechnology Research Center (CSIC-Universidad de Oviedo), El Entrego, 33940, Asturias, Spain
| | - Jaime Ferrer
- Departamento de Física, Universidad de Oviedo, 33007, Oviedo, Spain. .,Nanomaterials and Nanotechnology Research Center (CSIC-Universidad de Oviedo), El Entrego, 33940, Asturias, Spain.
| | - Colin J Lambert
- Quantum Technology Centre, Lancaster University, LA1 4YB, Lancaster, United Kingdom.
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16
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Sadeghi H, Sangtarash S, Lambert C. Robust Molecular Anchoring to Graphene Electrodes. NANO LETTERS 2017; 17:4611-4618. [PMID: 28700831 DOI: 10.1021/acs.nanolett.7b01001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent advances in the engineering of picoscale gaps between electroburnt graphene electrodes provide new opportunities for studying electron transport through electrostatically gated single molecules. But first we need to understand and develop strategies for anchoring single molecules to such electrodes. Here, for the first time we present a systematic theoretical study of transport properties using four different modes of anchoring zinc-porphyrin monomer, dimer, and trimer molecular wires to graphene electrodes. These involve either amine anchor groups, covalent C-C bonds to the edges of the graphene, or coupling via π-π stacking of planar polyaromatic hydrocarbons formed from pyrene or tetrabenzofluorene (TBF). π-π stacked pyrene anchors are particularly stable, which may be advantageous for forming robust single-molecule transistors. Despite their planar, multiatom coupling to the electrodes, pyrene anchors can exhibit both destructive interference and different degrees of constructive interference, depending on their connectivity to the porphyrin wire, which makes them attractive also for thermoelectricity. TBF anchors are more weakly coupled to both the graphene and the porphyrin wires and induce negative differential conductance at finite source-drain voltages. Furthermore, although direct C-C covalent bonding to the edges of graphene electrodes yields the highest electrical conductance, electron transport is significantly affected by the shape and size of the graphene electrodes because the local density of states at the carbon atoms connecting the electrode edges to the molecule is sensitive to the electrode surface shape. This sensitivity suggests that direct C-C bonding may be the most desirable for sensing applications. The ordering of the low-bias electrical conductances with different anchors is as follows: direct C-C coupling > π-π stacking with the pyrene anchors > direct coupling via amine anchors > π-π stacking with TBF anchors. Despite this dependency of conductances on the mode of anchoring, the decay of conductance with the length of the zinc-porphyrin wires is relatively insensitive with the associated attenuation factor β lying between 0.9 and 0.11 Å-1.
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Affiliation(s)
- Hatef Sadeghi
- Quantum Technology Centre, Department of Physics, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Sara Sangtarash
- Quantum Technology Centre, Department of Physics, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Colin Lambert
- Quantum Technology Centre, Department of Physics, Lancaster University , Lancaster LA1 4YB, United Kingdom
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17
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Noori M, Sadeghi H, Lambert CJ. High-performance thermoelectricity in edge-over-edge zinc-porphyrin molecular wires. NANOSCALE 2017; 9:5299-5304. [PMID: 28398431 DOI: 10.1039/c6nr09598d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
If high efficiency organic thermoelectric materials could be identified, then these would open the way to a range of energy harvesting technologies and Peltier coolers using flexible and transparent thin-film materials. We have compared the thermoelectric properties of three zinc porphyrin (ZnP) dimers and a ZnP monomer and found that the "edge-over-edge" dimer formed from stacked ZnP rings possesses a high electrical conductance, negligible phonon thermal conductance and a high Seebeck coefficient of the order of 300 μV K-1. These combine to yield a predicted room-temperature figure of merit of ZT ≈ 4, which is the highest room-temperature ZT ever reported for a single organic molecule. This high value of ZT is a consequence of the low phonon thermal conductance arising from the stacked nature of the porphyrin rings, which hinders phonon transport through the edge-over-edge molecule and enhances the Seebeck coefficient.
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Affiliation(s)
- Mohammed Noori
- Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK. and Department of Physics, College of Science, Thi-Qar University, Thi-Qar, Iraq
| | - Hatef Sadeghi
- Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
| | - Colin J Lambert
- Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
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18
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Han H, Zhang Y, Wang N, Samani MK, Ni Y, Mijbil ZY, Edwards M, Xiong S, Sääskilahti K, Murugesan M, Fu Y, Ye L, Sadeghi H, Bailey S, Kosevich YA, Lambert CJ, Liu J, Volz S. Functionalization mediates heat transport in graphene nanoflakes. Nat Commun 2016; 7:11281. [PMID: 27125636 PMCID: PMC4855536 DOI: 10.1038/ncomms11281] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 03/08/2016] [Indexed: 12/18/2022] Open
Abstract
The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by ∼28 °C for a chip operating at 1,300 W cm−2. Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene–graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in-plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime. The high thermal conductivity of graphene is considerably reduced when the two-dimensional material is in contact with a substrate. Here, the authors show that thermal management of a micro heater is improved using graphene-based films covalently bonded by amino-silane molecules to graphene oxide.
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Affiliation(s)
- Haoxue Han
- Laboratoire EM2C, CNRS, CentraleSupélec, Université Paris-Saclay, Grande Voie des Vignes, 92295 Châtenay-Malabry, France
| | - Yong Zhang
- SMIT Center, School of Automation and Mechanical Engineering and Institute of NanomicroEnergy, Shanghai University, 20 Chengzhong Road, Shanghai 201800, China.,Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Nan Wang
- Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Majid Kabiri Samani
- Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Yuxiang Ni
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, Minnesota 55455, USA
| | - Zainelabideen Y Mijbil
- Quantum Technology Center, Physics Department, Lancaster University, Lancaster LA1 4YB, UK.,Science Department, Veterinary Medicine College, Al-Qasim Green University, Babylon, Iraq
| | - Michael Edwards
- Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Shiyun Xiong
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Kimmo Sääskilahti
- Department of Biomedical Engineering and Computational Science, Aalto University, FI-00076 Aalto, Finland
| | - Murali Murugesan
- Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Yifeng Fu
- Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden.,SHT Smart High Tech AB, Ascherbergsgatan 46, SE-411 33 Gothenburg, Sweden
| | - Lilei Ye
- SHT Smart High Tech AB, Ascherbergsgatan 46, SE-411 33 Gothenburg, Sweden
| | - Hatef Sadeghi
- Quantum Technology Center, Physics Department, Lancaster University, Lancaster LA1 4YB, UK
| | - Steven Bailey
- Quantum Technology Center, Physics Department, Lancaster University, Lancaster LA1 4YB, UK
| | - Yuriy A Kosevich
- Laboratoire EM2C, CNRS, CentraleSupélec, Université Paris-Saclay, Grande Voie des Vignes, 92295 Châtenay-Malabry, France.,Department of Polymers and Composite Materials, Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygin Street 4, 119991 Moscow, Russia
| | - Colin J Lambert
- Quantum Technology Center, Physics Department, Lancaster University, Lancaster LA1 4YB, UK
| | - Johan Liu
- SMIT Center, School of Automation and Mechanical Engineering and Institute of NanomicroEnergy, Shanghai University, 20 Chengzhong Road, Shanghai 201800, China.,Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, SE-412 96 Gothenburg, Sweden
| | - Sebastian Volz
- Laboratoire EM2C, CNRS, CentraleSupélec, Université Paris-Saclay, Grande Voie des Vignes, 92295 Châtenay-Malabry, France
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Al-Galiby QH, Sadeghi H, Algharagholy LA, Grace I, Lambert C. Tuning the thermoelectric properties of metallo-porphyrins. NANOSCALE 2016; 8:2428-2433. [PMID: 26754271 DOI: 10.1039/c5nr06966a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigated the thermoelectric properties of metalloporphyrins connected by thiol anchor groups to gold electrodes. By varying the transition metal-centre over the family Mn, Co, Ni, Cu, Fe, and Zn we are able to tune the molecular energy levels relative to the Fermi energy of the electrodes. The resulting single-molecule room-temperature thermopowers range from almost zero for Co and Cu centres, to +80 μV K(-1) and +230 μV K(-1) for Ni and Zn respectively. In contrast, the thermopowers with Mn(II) or Fe(II) metal centres are negative and lie in the range -280 to -260 μV K(-1). Complexing these with a counter anion to form Fe(III) and Mn(III) changes both the sign and magnitude of their thermopowers to +218 and +95 respectively. The room-temperature power factors of Mn(II), Mn(III), Fe(III), Zn and Fe(II) porphyrins are predicted to be 5.9 × 10(-5) W m(-1) K(-2), 5.4 × 10(-4) W m(-1) K(-2), 9.5 × 10(-4) W m(-1) K(-2), 1.6 × 10(-4) W m(-1) K(-2) and 2.3 × 10(-4) W m(-1) K(-2) respectively, which makes these attractive materials for molecular-scale thermoelectric devices.
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Affiliation(s)
- Qusiy H Al-Galiby
- Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. and Physics Department, Al-Qadisiyah University, Diwaniyah, 58002, Iraq
| | - Hatef Sadeghi
- Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK.
| | - Laith A Algharagholy
- Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. and College of Basic Education, Sumer University, Al-Refayee, Thi-Qar 64001, Iraq
| | - Iain Grace
- Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK.
| | - Colin Lambert
- Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK.
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Algharagholy LA, Al-Galiby Q, Marhoon HA, Sadeghi H, Abduljalil HM, Lambert CJ. Tuning thermoelectric properties of graphene/boron nitride heterostructures. NANOTECHNOLOGY 2015; 26:475401. [PMID: 26528629 DOI: 10.1088/0957-4484/26/47/475401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couples states in the graphene, to form mini-bands. In un-doped nanoribbons, the mini bands are symmetrically positioned relative to the Fermi energy and do not enhance thermoelectric performance significantly. In contrast, when the ribbons are doped by electron donating or electron accepting adsorbates, the thermopower S and electronic figure of merit are enhanced and either positive or negative thermopowers can be obtained. In the most favourable case, doping with the electron donor tetrathiafulvalene increases the room-temperature thermopower to -284 μv K(-1) and doping by the electron acceptor tetracyanoethylene increases S to 210 μv K(-1). After including both electron and phonon contributions to the thermal conductance, figures of merit ZT up to of order 0.9 are obtained.
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Affiliation(s)
- Laith A Algharagholy
- College of Computer Science and Mathematics, Al-Qadisiyah University, Diwaniyah, Iraq. Department of Physics, Lancaster University, Lancaster LA1 4YB, UK. Quantum Technology Centre, Department of Physics, Lancaster University, LA1 4YB Lancaster, UK. College of Basic Education, Sumer University, Al-Refayee, Thi-Qar, Iraq
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21
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Sadeghi H, Sangtarash S, Lambert CJ. Oligoyne Molecular Junctions for Efficient Room Temperature Thermoelectric Power Generation. NANO LETTERS 2015; 15:7467-72. [PMID: 26458053 DOI: 10.1021/acs.nanolett.5b03033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Understanding phonon transport at a molecular scale is fundamental to the development of high-performance thermoelectric materials for the conversion of waste heat into electricity. We have studied phonon and electron transport in alkane and oligoyne chains of various lengths and find that, due to the more rigid nature of the latter, the phonon thermal conductances of oligoynes are counterintuitively lower than that of the corresponding alkanes. The thermal conductance of oligoynes decreases monotonically with increasing length, whereas the thermal conductance of alkanes initially increases with length and then decreases. This difference in behavior arises from phonon filtering by the gold electrodes and disappears when higher-Debye-frequency electrodes are used. Consequently a molecule that better transmits higher-frequency phonon modes, combined with a low-Debye-frequency electrode that filters high-energy phonons is a viable strategy for suppressing phonon transmission through the molecular junctions. The low thermal conductance of oligoynes, combined with their higher thermopower and higher electrical conductance lead to a maximum thermoelectric figure of merit of ZT = 1.4, which is several orders of magnitude higher than that of alkanes.
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Affiliation(s)
- Hatef Sadeghi
- Quantum Technology Centre, Lancaster University , LA1 4YB Lancaster, United Kingdom
| | - Sara Sangtarash
- Quantum Technology Centre, Lancaster University , LA1 4YB Lancaster, United Kingdom
| | - Colin J Lambert
- Quantum Technology Centre, Lancaster University , LA1 4YB Lancaster, United Kingdom
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Sadeghi H, Sangtarash S, Lambert CJ. Electron and heat transport in porphyrin-based single-molecule transistors with electro-burnt graphene electrodes. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1413-20. [PMID: 26199845 PMCID: PMC4505091 DOI: 10.3762/bjnano.6.146] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/03/2015] [Indexed: 05/13/2023]
Abstract
We have studied the charge and thermal transport properties of a porphyrin-based single-molecule transistor with electro-burnt graphene electrodes (EBG) using the nonequilibrium Green's function method and density functional theory. The porphyrin-based molecule is bound to the EBG electrodes by planar aromatic anchor groups. Due to the efficient π-π overlap between the anchor groups and graphene and the location of frontier orbitals relative to the EBG Fermi energy, we predict HOMO-dominated transport. An on-off ratio as high as 150 is predicted for the device, which could be utilized with small gate voltages in the range of ±0.1 V. A positive thermopower of +280 μV/K is predicted for the device at the theoretical Fermi energy. The sign of the thermopower could be changed by tuning the Fermi energy. By gating the junction and changing the Fermi energy by +10 meV, this can be further enhanced to +475 μV/K. Although the electrodes and molecule are symmetric, the junction itself can be asymmetric due to different binding configurations at the electrodes. This can lead to rectification in the current-voltage characteristic of the junction.
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Affiliation(s)
- Hatef Sadeghi
- Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK
| | - Sara Sangtarash
- Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK
| | - Colin J Lambert
- Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK
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