We focus on two new 21) materials, i.e., monolayer and bilayer silicon phosphides (Sil P1). Based on the elastic- scattering Green's function, the electronic-transport properties of two-dimensional monolayer and b...We focus on two new 21) materials, i.e., monolayer and bilayer silicon phosphides (Sil P1). Based on the elastic- scattering Green's function, the electronic-transport properties of two-dimensional monolayer and bilayer Au- Si1P1-Au molecular junctions are studied. It is found that their bandgaps are narrow (0.16eV for a monolayer molecular junction and 0.26 e V for a bilayer molecular junction). Moreover, the calculated current-voltage char- acteristics indicate that the monolayer molecular junction provides constant output current (20 hA) over a wide voltage range, and the bilayer molecular junction provides higher current (42 hA).展开更多
We investigate the electronic-transport properties of two-dimensional monolayer films from Au-P-Au molecular junction to Au-Si-Au molecular junction using elastic scattering Green's function theory. In the process of...We investigate the electronic-transport properties of two-dimensional monolayer films from Au-P-Au molecular junction to Au-Si-Au molecular junction using elastic scattering Green's function theory. In the process of replacing the P atoms with Si atoms every other line from the middle of monolayer blue phosphorus molecular structure, the substitution of Si atoms changes the properties of Au-P-Au molecular junction significantly. Interestingly, the current value has a symmetric change as a parabolic curve with the peak appearing in Au-Si_1P_1-Au molecular junction, which provides the most stable current of 15.00 nA in a wide voltage range of 0.70-2.70 V.Moreover, the current-voltage characteristics of the structures indicate that the steps tend to disappear revealing the property similar to metal when the Si atoms dominate the molecular junction.展开更多
A first-principles computational method based on the hybrid density functional theory is developed to simulate the electronic transport properties of oligomeric phenylene ethynylene molecular junctions with H2O molecu...A first-principles computational method based on the hybrid density functional theory is developed to simulate the electronic transport properties of oligomeric phenylene ethynylene molecular junctions with H2O molecules accumulated in the vicinity as recently reported by Na et al. [Nanotechnology 18 424001 (2007)]. The numerical results show that the hydrogen bonds between the oxygen atoms of the oligomeric phenylene ethynylene molecule and H2O molecules result in the localisation of the molecular orbitals and lead to the lower transition peaks. The H2O molecular chains accumulated in the vicinity of the molecular junction can not only change the electronic structure of the molecular junctions, but also open additional electronic transport pathways. The obvious influence of H2O molecules on the electronic structure of the molecular junction and its electronic transport properties is thus demonstrated.展开更多
Excellent thermoelectric performance in molecular junctions requires a high power factor, a low thermal conductance, and a maximum figure of merit(ZT) near the Fermi level. In the present work, we used density functio...Excellent thermoelectric performance in molecular junctions requires a high power factor, a low thermal conductance, and a maximum figure of merit(ZT) near the Fermi level. In the present work, we used density functional theory in combination with a nonequilibrium Green’s function to investigate the thermoelectric performance of carbon chain-graphene junctions with both strong-coupling and weak-coupling contact between the electrodes and the molecules. The results revealed that a room temperature ZT of 4 could be obtained for the weak-coupling molecular junction, approximately one order of magnitude higher than that reached by the strong-coupling junction. The reason for this is that strong interfacial scattering suppresses most of the phonon modes in weak-coupling systems, resulting in ultralow phonon thermal conductance. The influence of electrode width,electrode doping, and electrochemical gating on the thermoelectric performance of the weak-coupling system was also investigated, and the results revealed that an excellent thermoelectric performance can be obtained near the Fermi level.展开更多
In this article, we report on the characterization of various molecular junctions' current-voltage characteristics (Ⅰ-Ⅴ curves) evolution under mechanical modulations, by employing a novel electrochemically assis...In this article, we report on the characterization of various molecular junctions' current-voltage characteristics (Ⅰ-Ⅴ curves) evolution under mechanical modulations, by employing a novel electrochemically assisted-mechanically controllable break junction (EC-MCBJ) method. For 1,4-benzenedithiol, the Ⅰ-Ⅴ curves measured at constant electrode pair separation show excellent reproducibility, indicating the feasibility of our EC-MCBJ method for fabricating molecular junctions. For ferrocene-bisvinylphenylmethyl dithiol (Fc-VPM), an anomalous type of Ⅰ-Ⅴ curve was observed by the particular control over the stepping motor. This phenomenon is rationalized assuming a model of atomic contact evolution with the presence of molecular junctions. To test this hypothesized model, a molecule with a longer length, 1,3-butadiyne-linked dinuclear ruthenium(H) complex (Ru-1), was implemented, and the Ⅰ-Ⅴ curve evolution was investigated under similar circumstances. Compared with Fc-VPM, the observed Ⅰ-Ⅴ curves show close analogy and minor differences, and both of them fit the hypothesized model well.展开更多
Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has bee...Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position,and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGa In as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy(UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory(DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital(HOMO) on imidazole group of the histidine, which decreased charge transport barrier.展开更多
Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N...Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N- SMM-N systems. We mainly focus on the interplay of SMM's bistable character and electron-phonon coupling. It is found that when SMM is trapped in one of the lowest bistable states, it can generate phonon-assisted spin- polarized currents. At the up-spin transport channel, it is accompanied by a phonon-assisted up-spin current, while at the down-spin transport channel, it is accompanied by a phonon-assisted down-spin current.展开更多
Based on the density functional theory combined with the nonequilibrium Green function methodology,we have studied the thermally-driven spin-dependent transport properties of a combinational molecular junction consist...Based on the density functional theory combined with the nonequilibrium Green function methodology,we have studied the thermally-driven spin-dependent transport properties of a combinational molecular junction consisting of a planar four-coordinate Fe molecule and a 15,16-dinitrile dihydropyrene/cyclophanediene molecule,with single-walled carbon nanotube bridge and electrode.Our results show that the magnetic field and light can effectively regulate the thermallydriven spin-dependent currents.Perfect thermal spin-filtering effect and good thermal switching effect are realized.The results are explained by the Fermi-Dirac distribution function,the spin-resolved transmission spectra,the spatial distribution of molecular projected self-consistent Hamiltonian orbitals,and the spin-resolved current spectra.On the basis of these thermally-driven spin-dependent transport properties,we have further designed three basic thermal spin molecular AND,OR,and NOT gates.展开更多
In this paper the charge transfer and variation of potential distribution upon formation of 4, 4'-bipyridine molecular junction have been investigated by applying hybrid density-functional theory (B3LYP) at ab init...In this paper the charge transfer and variation of potential distribution upon formation of 4, 4'-bipyridine molecular junction have been investigated by applying hybrid density-functional theory (B3LYP) at ab initio level. The numerical results show that there exist charge-accumulation and charge-depletion regions located at respective inside and outside of interfaces. The variation of potential distribution is obvious at interfaces. When distance between electrodes is changed, the charge transfer and variation of potential distribution clearly have distance-dependent performance. It is demonstrated that the contact structure between the molecule and electrodes is another key factor for dominating the properties of molecular junction. The qualitative explanation for experimental results is suggested.展开更多
Developments in advanced manufacturing have promoted the miniaturization of semiconductor electronic devices to a near-atomic scale,which continuously follows the‘top-down’construction method.However,huge challenges...Developments in advanced manufacturing have promoted the miniaturization of semiconductor electronic devices to a near-atomic scale,which continuously follows the‘top-down’construction method.However,huge challenges have been encountered with the exponentially increased cost and inevitably prominent quantum effects.Molecular electronics is a highly interdisciplinary subject that studies the quantum behavior of electrons tunneling in molecules.It aims to assemble electronic devices in a‘bottom-up’manner on this scale through a single molecule,thereby shedding light on the future design of logic circuits with new operating principles.The core technologies in this field are based on the rapid development of precise fabrication at a molecular scale,regulation at a quantum scale,and related applications of the basic electronic component of the‘electrode-molecule-electrode junction’.Therefore,the quantum charge transport properties of the molecule can be controlled to pave the way for the bottom-up construction of single-molecule devices.The review firstly focuses on the collection and classification of the construction methods for molecular junctions.Thereafter,various characterization and regulation methods for molecular junctions are discussed,followed by the properties based on tunneling theory at the quantum scale of the corresponding molecular electronic devices.Finally,a summary and perspective are given to discuss further challenges and opportunities for the future design of electronic devices.展开更多
The inelastic electron tunneling spectroscopy(IETS) of four edge-modified finite-size grapheme nanoribbon(GNR)-based molecular devices has been studied by using the density functional theory and Green's function ...The inelastic electron tunneling spectroscopy(IETS) of four edge-modified finite-size grapheme nanoribbon(GNR)-based molecular devices has been studied by using the density functional theory and Green's function method. The effects of atomic structures and connection types on inelastic transport properties of the junctions have been studied. The IETS is sensitive to the electrode connection types and modification types. Comparing with the pure hydrogen edge passivation systems, we conclude that the IETS for the lower energy region increases obviously when using donor–acceptor functional groups as the edge modification types of the central scattering area. When using donor–acceptor as the electrode connection groups, the intensity of IETS increases several orders of magnitude than that of the pure ones. The effects of temperature on the inelastic electron tunneling spectroscopy also have been discussed. The IETS curves show significant fine structures at lower temperatures. With the increasing of temperature, peak broadening covers many fine structures of the IETS curves.The changes of IETS in the low-frequency region are caused by the introduction of the donor–acceptor groups and the population distribution of thermal particles. The effect of Fermi distribution on the tunneling current is persistent.展开更多
The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green's function formalism combined with ab in...The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green's function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule.展开更多
Comprehensive Summary,The charge transport through peptides can imitate the corresponding processes in more complicated proteins,enabling us to develop high-performance bioelectronic devices and to understand the mech...Comprehensive Summary,The charge transport through peptides can imitate the corresponding processes in more complicated proteins,enabling us to develop high-performance bioelectronic devices and to understand the mechanisms of biomolecular recognition and information transfer.While charge transport modulation through individual peptides has been achieved via various covalent strategies,the intermolecular modulation is still very challenging,which may capture the charge transport between proteins.To tackle this challenge,we used well-defined self-assembled monolayers(SAMs)of oligopeptides as a model to imitate the interface of proteins and explored an interfacial amino acid strategy for charge transport modulation.We showed that non-covalently interfaced charged amino acids(e.g.,arginine)effectively attenuated the charge transport of glutamic acid terminated polyglycine peptide SAMs.By analyzing the relationship of the charge transport with the molecular frontier orbital relative to the Fermi energy level of the electrode,the molecule-electrodes coupling(Γ),and the trends in skewness and kurtosis with voltage and the dielectric constant(εr),we showed that the attenuation was from the decreasedΓand the reduced polarizability.We present an efficient strategy to modulate the charge transport of oligopeptide-SAM junctions by intermolecular interactions,which will advance our understanding of charge transport in biological systems and facilitate developing future electronics.展开更多
Recent years have witnessed the fabrication of various non-covalent interaction-based molecular electronic devices.In the noncovalent interaction-based molecular devices,the strength of the interfacial coupling betwee...Recent years have witnessed the fabrication of various non-covalent interaction-based molecular electronic devices.In the noncovalent interaction-based molecular devices,the strength of the interfacial coupling between molecule and electrode is weakened compared to that of the covalent interaction-based molecular devices,which provides wide applications in fabricating versatile molecular devices.In this review,we start with the methods capable of fabricating graphene-based nanogaps,and the following routes to construct non-covalent interaction-based molecular junctions with graphene electrodes.Then we give an introduction to the reported non-covalent interaction-based molecular devices with graphene electrodes equipped with different electrical functions.Moreover,we summarize the recent progress in the design and fabrication of new-type molecular devices based on graphene and graphene-like two-dimensional(2D)materials.The review ends with a prospect on the challenges and opportunities of non-covalent interaction-based molecular electronics in the near future.展开更多
Exploring the charge transport properties and electronic functions of molecules is of primary interest in the area of molecular electronics.Conjugated polymers(CPs) represent an attractive class of molecular candida...Exploring the charge transport properties and electronic functions of molecules is of primary interest in the area of molecular electronics.Conjugated polymers(CPs) represent an attractive class of molecular candidates,benefiting from their outstanding optoelectronic properties.However,they have been less studied compared with the small-molecule family,mainly due to the difficulties in incorporating CPs into molecular junctions.In this review,we present a summary on how to fabricate CP-based singlechain and monolayered junctions,then discuss the transport behaviors of CPs in different junction architectures and finally introduce the potential applications of CPs in molecular-scale electronic devices.Although the research on CP-based molecular electronics is still at the initial stage,it is widely accepted that(1) CP chains are able to mediate long-range charge transport if their molecular electronic structures are properly designed,which makes them potential molecular wires,and(2) the intrinsic optoelectronic properties of CPs and the possibility of incorporating desirable functionalities by synthetic strategies imply the potential of employing tailor-made polymeric components as alternatives to small molecules for future molecular-scale electronics.展开更多
We have combined molecular dynamics simulations with first-principles calculations to study electron transport in a single molecular junction of perylene tetracarboxylic diimide (PTCDI) in aqueous solution under exter...We have combined molecular dynamics simulations with first-principles calculations to study electron transport in a single molecular junction of perylene tetracarboxylic diimide (PTCDI) in aqueous solution under external electric gate fields. It is found that the statistics of the molecular conductance are very sensitive to the strength of the electric field. The statistics of the molecular conductance are strongly associated with the thermal fluctuation of the water molecules around the PTCDI molecule. Our simulations reproduce the experimentally observed three orders of magnitude enhancement of the conductance, as well as the temperature dependent conductance, under the electrochemical gates. The effects of the molecular polarization and the dipole rearrangement of the aqueous solution are also discussed.展开更多
By wiring molecules into circuits, "molecular electronics" aims at studying electronic properties of single molecules and their ensembles, on this basis exploiting their intrinsic functionalities, and eventually app...By wiring molecules into circuits, "molecular electronics" aims at studying electronic properties of single molecules and their ensembles, on this basis exploiting their intrinsic functionalities, and eventually applying them as building blocks of electronic components for future electronic devices. Herein, fabricating reliable solid-state molecular devices and developing synthetic molecules endowed with desirable electronic properties, have been two major tasks since the dawn of molecular electronics. This review focuses on recent advances and efforts regarding the main challenges in this field, highlighting fabrication of nanogap electrodes for single-molecule junctions, and self-assembled-monolayers (SAMs) for functional devices. The prospect of molecular-scale electronics is also discussed.展开更多
Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have b...Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11374033
文摘We focus on two new 21) materials, i.e., monolayer and bilayer silicon phosphides (Sil P1). Based on the elastic- scattering Green's function, the electronic-transport properties of two-dimensional monolayer and bilayer Au- Si1P1-Au molecular junctions are studied. It is found that their bandgaps are narrow (0.16eV for a monolayer molecular junction and 0.26 e V for a bilayer molecular junction). Moreover, the calculated current-voltage char- acteristics indicate that the monolayer molecular junction provides constant output current (20 hA) over a wide voltage range, and the bilayer molecular junction provides higher current (42 hA).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374033,11774030,51735001 and 61775016the Fundamental Research Funds for the Central Universities under Grant No 2017CX10007
文摘We investigate the electronic-transport properties of two-dimensional monolayer films from Au-P-Au molecular junction to Au-Si-Au molecular junction using elastic scattering Green's function theory. In the process of replacing the P atoms with Si atoms every other line from the middle of monolayer blue phosphorus molecular structure, the substitution of Si atoms changes the properties of Au-P-Au molecular junction significantly. Interestingly, the current value has a symmetric change as a parabolic curve with the peak appearing in Au-Si_1P_1-Au molecular junction, which provides the most stable current of 15.00 nA in a wide voltage range of 0.70-2.70 V.Moreover, the current-voltage characteristics of the structures indicate that the steps tend to disappear revealing the property similar to metal when the Si atoms dominate the molecular junction.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10804064 and 10674084)
文摘A first-principles computational method based on the hybrid density functional theory is developed to simulate the electronic transport properties of oligomeric phenylene ethynylene molecular junctions with H2O molecules accumulated in the vicinity as recently reported by Na et al. [Nanotechnology 18 424001 (2007)]. The numerical results show that the hydrogen bonds between the oxygen atoms of the oligomeric phenylene ethynylene molecule and H2O molecules result in the localisation of the molecular orbitals and lead to the lower transition peaks. The H2O molecular chains accumulated in the vicinity of the molecular junction can not only change the electronic structure of the molecular junctions, but also open additional electronic transport pathways. The obvious influence of H2O molecules on the electronic structure of the molecular junction and its electronic transport properties is thus demonstrated.
基金the National Key Research and Development Program of China(Grant No.2017YFB0701602)the National Natural Science Foundation of China(Grant No.11674092)。
文摘Excellent thermoelectric performance in molecular junctions requires a high power factor, a low thermal conductance, and a maximum figure of merit(ZT) near the Fermi level. In the present work, we used density functional theory in combination with a nonequilibrium Green’s function to investigate the thermoelectric performance of carbon chain-graphene junctions with both strong-coupling and weak-coupling contact between the electrodes and the molecules. The results revealed that a room temperature ZT of 4 could be obtained for the weak-coupling molecular junction, approximately one order of magnitude higher than that reached by the strong-coupling junction. The reason for this is that strong interfacial scattering suppresses most of the phonon modes in weak-coupling systems, resulting in ultralow phonon thermal conductance. The influence of electrode width,electrode doping, and electrochemical gating on the thermoelectric performance of the weak-coupling system was also investigated, and the results revealed that an excellent thermoelectric performance can be obtained near the Fermi level.
基金This work was supported by the National Basic Research Program of China (Nos. 2011YQ030124, 2014CB845603, and 2015CB932301), National Natural Science Foundation of China (Nos. 91427304, 21321062, 21303114, 21403181, and 21503179), Natural Science Foundation of Fujian Province (No. 2012J05034), and by CNRS UMR 8640 PASTEUR and LIA CNRS NanoBioCatEchem.
文摘In this article, we report on the characterization of various molecular junctions' current-voltage characteristics (Ⅰ-Ⅴ curves) evolution under mechanical modulations, by employing a novel electrochemically assisted-mechanically controllable break junction (EC-MCBJ) method. For 1,4-benzenedithiol, the Ⅰ-Ⅴ curves measured at constant electrode pair separation show excellent reproducibility, indicating the feasibility of our EC-MCBJ method for fabricating molecular junctions. For ferrocene-bisvinylphenylmethyl dithiol (Fc-VPM), an anomalous type of Ⅰ-Ⅴ curve was observed by the particular control over the stepping motor. This phenomenon is rationalized assuming a model of atomic contact evolution with the presence of molecular junctions. To test this hypothesized model, a molecule with a longer length, 1,3-butadiyne-linked dinuclear ruthenium(H) complex (Ru-1), was implemented, and the Ⅰ-Ⅴ curve evolution was investigated under similar circumstances. Compared with Fc-VPM, the observed Ⅰ-Ⅴ curves show close analogy and minor differences, and both of them fit the hypothesized model well.
基金supported by the National Natural Science Foundation of China (Nos. 21773169, 21973069, 21805144)Natural Science Foundation of Zhejiang Province (No. LY18B020016)the PEIYANG Young Scholars Program of Tianjin University (No. 2018XRX-0007)。
文摘Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position,and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGa In as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy(UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory(DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital(HOMO) on imidazole group of the histidine, which decreased charge transport barrier.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11504210,11504211,11504212,11274207,11274208,11174115 and 11325417the Key Program of the Ministry of Education of China under Grant No 212018+2 种基金Shanxi Provincial Scientific and Technological Project(2015031002-2)Shanxi Provincial Natural Science Foundation under Grant Nos2013011007-2 and 2013021010-5Outstanding Innovative Teams of Higher Learning Institutions of Shanxi Province
文摘Owing to the bistable character of the single molecular magnet (SMM), it can generate 100% spin-polarized currents even connected with normal (N) leads. In this work, we study the phonon-assisted spin current in N- SMM-N systems. We mainly focus on the interplay of SMM's bistable character and electron-phonon coupling. It is found that when SMM is trapped in one of the lowest bistable states, it can generate phonon-assisted spin- polarized currents. At the up-spin transport channel, it is accompanied by a phonon-assisted up-spin current, while at the down-spin transport channel, it is accompanied by a phonon-assisted down-spin current.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021MA059)the Major Scientific and Technological Innovation Project(MSTIP)of Shandong Province,China(Grant No.2019JZZY010209)。
文摘Based on the density functional theory combined with the nonequilibrium Green function methodology,we have studied the thermally-driven spin-dependent transport properties of a combinational molecular junction consisting of a planar four-coordinate Fe molecule and a 15,16-dinitrile dihydropyrene/cyclophanediene molecule,with single-walled carbon nanotube bridge and electrode.Our results show that the magnetic field and light can effectively regulate the thermallydriven spin-dependent currents.Perfect thermal spin-filtering effect and good thermal switching effect are realized.The results are explained by the Fermi-Dirac distribution function,the spin-resolved transmission spectra,the spatial distribution of molecular projected self-consistent Hamiltonian orbitals,and the spin-resolved current spectra.On the basis of these thermally-driven spin-dependent transport properties,we have further designed three basic thermal spin molecular AND,OR,and NOT gates.
基金Project supported by the National Natural Science Foundation of China (Grant No 10674084), the Natural Science Foundation of Shandong Province, China (Grant No Y2004A08) and the Doctorate Foundation of the State Education Ministry of China (Grant No 20040445001).
文摘In this paper the charge transfer and variation of potential distribution upon formation of 4, 4'-bipyridine molecular junction have been investigated by applying hybrid density-functional theory (B3LYP) at ab initio level. The numerical results show that there exist charge-accumulation and charge-depletion regions located at respective inside and outside of interfaces. The variation of potential distribution is obvious at interfaces. When distance between electrodes is changed, the charge transfer and variation of potential distribution clearly have distance-dependent performance. It is demonstrated that the contact structure between the molecule and electrodes is another key factor for dominating the properties of molecular junction. The qualitative explanation for experimental results is suggested.
基金supported by the National Natural Science Foundation of China(Nos.22173075,21933012,31871877)the National Key Research and Development Program of China(2017YFA0204902)the Fundamental Research Funds for the Central Universities(Nos.20720200068,20720190002).
文摘Developments in advanced manufacturing have promoted the miniaturization of semiconductor electronic devices to a near-atomic scale,which continuously follows the‘top-down’construction method.However,huge challenges have been encountered with the exponentially increased cost and inevitably prominent quantum effects.Molecular electronics is a highly interdisciplinary subject that studies the quantum behavior of electrons tunneling in molecules.It aims to assemble electronic devices in a‘bottom-up’manner on this scale through a single molecule,thereby shedding light on the future design of logic circuits with new operating principles.The core technologies in this field are based on the rapid development of precise fabrication at a molecular scale,regulation at a quantum scale,and related applications of the basic electronic component of the‘electrode-molecule-electrode junction’.Therefore,the quantum charge transport properties of the molecule can be controlled to pave the way for the bottom-up construction of single-molecule devices.The review firstly focuses on the collection and classification of the construction methods for molecular junctions.Thereafter,various characterization and regulation methods for molecular junctions are discussed,followed by the properties based on tunneling theory at the quantum scale of the corresponding molecular electronic devices.Finally,a summary and perspective are given to discuss further challenges and opportunities for the future design of electronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304001,51272001,51472003,and 11174002)the National Key Basic Research Program of China(Grant No.2013CB632705)+4 种基金the Ph.D.Programs Foundation for the Youth Scholars of Ministry of Education of China(Grant No.20133401120002)the Foundation of State Key Laboratory for Modification of Chemical Fibers and Polymer Materials of Donghua University(Grant No.LK1217)the Foundation of Co-operative Innovation Research Center for Weak Signal-Detecting Materials and Devices Integration of Anhui University(Grant No.01001795-201410)the Key Project of the Foundation of Anhui Educational Committee,China(Grant No.KJ2013A035)the Ph.D.Programs Foundation of Anhui University,China(Grant No.33190134)
文摘The inelastic electron tunneling spectroscopy(IETS) of four edge-modified finite-size grapheme nanoribbon(GNR)-based molecular devices has been studied by using the density functional theory and Green's function method. The effects of atomic structures and connection types on inelastic transport properties of the junctions have been studied. The IETS is sensitive to the electrode connection types and modification types. Comparing with the pure hydrogen edge passivation systems, we conclude that the IETS for the lower energy region increases obviously when using donor–acceptor functional groups as the edge modification types of the central scattering area. When using donor–acceptor as the electrode connection groups, the intensity of IETS increases several orders of magnitude than that of the pure ones. The effects of temperature on the inelastic electron tunneling spectroscopy also have been discussed. The IETS curves show significant fine structures at lower temperatures. With the increasing of temperature, peak broadening covers many fine structures of the IETS curves.The changes of IETS in the low-frequency region are caused by the introduction of the donor–acceptor groups and the population distribution of thermal particles. The effect of Fermi distribution on the tunneling current is persistent.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374195 and 11405098)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2013FM006)
文摘The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green's function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule.
基金supported by financial support from the National Natural Science Foundation of China(21974102 and 21705019)the National Key R&D Program of China(2018YFA0703700).
文摘Comprehensive Summary,The charge transport through peptides can imitate the corresponding processes in more complicated proteins,enabling us to develop high-performance bioelectronic devices and to understand the mechanisms of biomolecular recognition and information transfer.While charge transport modulation through individual peptides has been achieved via various covalent strategies,the intermolecular modulation is still very challenging,which may capture the charge transport between proteins.To tackle this challenge,we used well-defined self-assembled monolayers(SAMs)of oligopeptides as a model to imitate the interface of proteins and explored an interfacial amino acid strategy for charge transport modulation.We showed that non-covalently interfaced charged amino acids(e.g.,arginine)effectively attenuated the charge transport of glutamic acid terminated polyglycine peptide SAMs.By analyzing the relationship of the charge transport with the molecular frontier orbital relative to the Fermi energy level of the electrode,the molecule-electrodes coupling(Γ),and the trends in skewness and kurtosis with voltage and the dielectric constant(εr),we showed that the attenuation was from the decreasedΓand the reduced polarizability.We present an efficient strategy to modulate the charge transport of oligopeptide-SAM junctions by intermolecular interactions,which will advance our understanding of charge transport in biological systems and facilitate developing future electronics.
基金the support from the National Natural Science Foundation of China(Nos.21973079 and 22032004)the National Key R&D Program of China(No.2017YFA0204902)the Fundamental Research Funds for the Central Universities(Xiamen University:No.20720190002).
文摘Recent years have witnessed the fabrication of various non-covalent interaction-based molecular electronic devices.In the noncovalent interaction-based molecular devices,the strength of the interfacial coupling between molecule and electrode is weakened compared to that of the covalent interaction-based molecular devices,which provides wide applications in fabricating versatile molecular devices.In this review,we start with the methods capable of fabricating graphene-based nanogaps,and the following routes to construct non-covalent interaction-based molecular junctions with graphene electrodes.Then we give an introduction to the reported non-covalent interaction-based molecular devices with graphene electrodes equipped with different electrical functions.Moreover,we summarize the recent progress in the design and fabrication of new-type molecular devices based on graphene and graphene-like two-dimensional(2D)materials.The review ends with a prospect on the challenges and opportunities of non-covalent interaction-based molecular electronics in the near future.
基金the financial support from 985/211 Project(No.WF220411002)Shanghai Jiao Tong University and the national "1000-talent Plan(Youth)"
文摘Exploring the charge transport properties and electronic functions of molecules is of primary interest in the area of molecular electronics.Conjugated polymers(CPs) represent an attractive class of molecular candidates,benefiting from their outstanding optoelectronic properties.However,they have been less studied compared with the small-molecule family,mainly due to the difficulties in incorporating CPs into molecular junctions.In this review,we present a summary on how to fabricate CP-based singlechain and monolayered junctions,then discuss the transport behaviors of CPs in different junction architectures and finally introduce the potential applications of CPs in molecular-scale electronic devices.Although the research on CP-based molecular electronics is still at the initial stage,it is widely accepted that(1) CP chains are able to mediate long-range charge transport if their molecular electronic structures are properly designed,which makes them potential molecular wires,and(2) the intrinsic optoelectronic properties of CPs and the possibility of incorporating desirable functionalities by synthetic strategies imply the potential of employing tailor-made polymeric components as alternatives to small molecules for future molecular-scale electronics.
基金This work was supported by the Swedish Research Council(VR),the Swedish National Infrastructure for Computing(SNIC)the Natural Science Foundation of China(No.20825312)and the Fok Ying Tong Education Foundation(No.111013).
文摘We have combined molecular dynamics simulations with first-principles calculations to study electron transport in a single molecular junction of perylene tetracarboxylic diimide (PTCDI) in aqueous solution under external electric gate fields. It is found that the statistics of the molecular conductance are very sensitive to the strength of the electric field. The statistics of the molecular conductance are strongly associated with the thermal fluctuation of the water molecules around the PTCDI molecule. Our simulations reproduce the experimentally observed three orders of magnitude enhancement of the conductance, as well as the temperature dependent conductance, under the electrochemical gates. The effects of the molecular polarization and the dipole rearrangement of the aqueous solution are also discussed.
基金support from the National Natural Science Foundation of China (No. 51673114)Shanghai Science and Technology Committee (No. 17ZR1447300)Basic Research Development Programme (No. 2017YFA0207500)
文摘By wiring molecules into circuits, "molecular electronics" aims at studying electronic properties of single molecules and their ensembles, on this basis exploiting their intrinsic functionalities, and eventually applying them as building blocks of electronic components for future electronic devices. Herein, fabricating reliable solid-state molecular devices and developing synthetic molecules endowed with desirable electronic properties, have been two major tasks since the dawn of molecular electronics. This review focuses on recent advances and efforts regarding the main challenges in this field, highlighting fabrication of nanogap electrodes for single-molecule junctions, and self-assembled-monolayers (SAMs) for functional devices. The prospect of molecular-scale electronics is also discussed.
基金supported by the National Natural Science Foundation of China(grant nos.T2222002,21973079,22032004,92161118,12174324,21991130,and 21905238)the Ministry of Science and Technology of the People’s Republic of China(grant no.2021YFA1201502)the Natural Science Foundation of Fujian Province(grant no.2021J06008).
文摘Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.