Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, lo...Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, low dimensional perovskites suffer fl＇om low power conversion efficiency （PCE） with respect to their three dimensional analogues. Therefore, it is imperative to find excellent low-dimensional perovskite materials for improving the PCE. Previous work has demonstrated that bulkier organic molecules, e,g., C6Hs（CH2）2NH3＋ （PEA＋）, CH3（CH2）3NH3＋（n-BAT, iso-BA＋）, C2H4NH3 ＋, and polyethylenimine cations （PEI＋）, play an important role in the formation of low-dimensional perovskites. In this review, we review the recent development of low dimensional perovskites for solar cells application in terms of film preparation, photophysics, and stability of perovskites, as well as the related device structure and physics. We have also discussed the future development of low-dimensional perovskites from materials design, fabri- cation processes, and device structure.展开更多
Seismic data reconstruction is an essential and yet fundamental step in seismic data processing workflow,which is of profound significance to improve migration imaging quality,multiple suppression effect,and seismic i...Seismic data reconstruction is an essential and yet fundamental step in seismic data processing workflow,which is of profound significance to improve migration imaging quality,multiple suppression effect,and seismic inversion accuracy.Regularization methods play a central role in solving the underdetermined inverse problem of seismic data reconstruction.In this paper,a novel regularization approach is proposed,the low dimensional manifold model(LDMM),for reconstructing the missing seismic data.Our work relies on the fact that seismic patches always occupy a low dimensional manifold.Specifically,we exploit the dimension of the seismic patches manifold as a regularization term in the reconstruction problem,and reconstruct the missing seismic data by enforcing low dimensionality on this manifold.The crucial procedure of the proposed method is to solve the dimension of the patches manifold.Toward this,we adopt an efficient dimensionality calculation method based on low-rank approximation,which provides a reliable safeguard to enforce the constraints in the reconstruction process.Numerical experiments performed on synthetic and field seismic data demonstrate that,compared with the curvelet-based sparsity-promoting L1-norm minimization method and the multichannel singular spectrum analysis method,the proposed method obtains state-of-the-art reconstruction results.展开更多
The characterization of microstructure for three kinds of typical low dimensional materials,such as ultrafine particle(zero- dimension),whisker(one- dimension)and thin film(two-dimensions),has been carried out.The met...The characterization of microstructure for three kinds of typical low dimensional materials,such as ultrafine particle(zero- dimension),whisker(one- dimension)and thin film(two-dimensions),has been carried out.The methods and criteria for the characterization are investigated and introduced.Some interesting results of the characterization are reported.展开更多
With the exponential growth of the internet of things,artificial intelligence,and energy-efficient high-volume data digital communications,there is an urgent demand to develop new information technologies with high st...With the exponential growth of the internet of things,artificial intelligence,and energy-efficient high-volume data digital communications,there is an urgent demand to develop new information technologies with high storage capacity.This needs to address the looming challenge of conventional Von Neumann architecture and Moore's law bottleneck for future data-intensive computing applications.A promising remedy lies in memristors,which offer distinct advantages of scalability,rapid access times,stable data retention,low power consumption,multistate storage capability and fast operation.Among the various materials used for active layers in memristors,low dimensional perovskite semiconductors with structural diversity and superior stability exhibit great potential for next generation memristor applications,leveraging hysteresis characteristics caused by ion migration and defects.In this review the progress of low-dimensional perovskite memory devices is comprehensively summarized.The working mechanism and fundamental processes,including ion migration dynamics,charge carrier transport and electronic resistance that underlies the switching behavior of memristors are discussed.Additionally,the device parameters are analyzed with special focus on the effective methods to improve electrical performance and operational stability.Finally,the challenges and perspective on major hurdles of low-dimensional perovskite memristors in the expansive application domains are provided.展开更多
In this review, we present a summary of some recent experiments on topological insulators （TIs） and superconducting nanowires and fihns. Electron electron interaction （EEI）, weak anti-localization （WAL） and anis...In this review, we present a summary of some recent experiments on topological insulators （TIs） and superconducting nanowires and fihns. Electron electron interaction （EEI）, weak anti-localization （WAL） and anisotropic magneto-resistance （AMR） effect fbund in topological insulator fihns by transport measurements are reported. Then, transport properties of superconducting films, bridges and nanowires and proximity effect in non-superconducting nanowires are described. Finally, the interplay between topological insulators and superconductors （SCs） is also discussed.展开更多
Recently,the development of materials with circularly polarized luminescence(CPL)has attracted numerous attentions owing to their potential applications in various fields.Among diverse mechanisms for the origin of chi...Recently,the development of materials with circularly polarized luminescence(CPL)has attracted numerous attentions owing to their potential applications in various fields.Among diverse mechanisms for the origin of chiroptical properties in low dimensional semiconductors(LDS),the self-assembly approach provides a powerful technique for acquisition of strong chiroptical activity.Benefiting from this approach,LDS could be endowed with CPL in which the dissymmetry factor,a vital parameter for evaluating the performance of CPL,could be greatly improved.In this review,state-of-the-art of selfassembled LDS will be summarized.The current challenges and perspectives in this emerging field are also presented.This review could not only provide insights of the fundamentals of self-assembled chirality,but also shine light for designing CPL-active functional nanomaterials toward their applications based on novel optoelectronic devices.展开更多
Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the ...Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimen- sion. In this paper, local-geometric-projection method is applied to obtain fow dimensional element from various target radiating noise and the derived phase portraits show obviously low dimensional attractors. Furthermore, attractor dimension and cross prediction error are used for classification. It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.展开更多
Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multicha...Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multichannel spike trains were recorded in rat prefrontal cortex during a work memory task in Y-maze.As discretesignals,spikes were transferred into cont inuous signals by estinating entropy.Then the normalized continuous signals were decomposed via non-negative sparse met hod.The non-negative components were extracted to reconstruct a low-dimensional ensemble,while none of the feature components were missed.The results showed that,for well-trained rats,neuronal ensemble activities in the prefrontal cortex changed dynamically during the.working memory task.And the neuronal ensemble is more explicit via using non-negative sparse coding.Our results indicate that the neuronal ensemblesparse coding method can effectively reduce the dimnension of neuronal activity and it is a useful tool to express neural coding.展开更多
In this paper we analyze a long standing problem of the appearance of spurious,non-physical solutions arising in the application of the effective mass theory to low dimensional nanostructures.The theory results in a s...In this paper we analyze a long standing problem of the appearance of spurious,non-physical solutions arising in the application of the effective mass theory to low dimensional nanostructures.The theory results in a system of coupled eigenvalue PDEs that is usually supplemented by interface boundary conditions that can be derived from a variational formulation of the problem.We analyze such a system for the envelope functions and show that a failure to restrict their Fourier expansion coeffi-cients to small k components would lead to the appearance of non-physical solutions.We survey the existing methodologies to eliminate this difficulty and propose a simple and effective solution.This solution is demonstrated on an example of a two-band model for both bulk materials and low-dimensional nanostructures.Finally,based on the above requirement of small k,we derive a model for nanostructures with cylindrical symmetry and apply the developed model to the analysis of quantum dots using an eight-band model.展开更多
This special issue will include reviews,regular papers,and short communications,and reports in the fields for next generation electronics and photonics.The topics include but not restricted in advanced microelectronic...This special issue will include reviews,regular papers,and short communications,and reports in the fields for next generation electronics and photonics.The topics include but not restricted in advanced microelectronic devices and materials,low-dimensional materials and novel nanodevice applications,flexible/wearable/implantable electronics,wide bandgap semiconductor materials and devices,photoelectronics,photonics,advanced display technologies,nanophotonics,integrated quantum photonics,photovoltaics,energy harvesting and self-powered wireless sensing,sensors,micro-actuators,MEMS,microfluidics,and bioMEMS,etc.展开更多
We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper crit...We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper critical field(Hc2)in parallel to surface orientation shows bending curvature close to critical temperature Tc,suggesting a two-dimensional(2D)nature of the samples.The 2D behavior is further supported by the angular dependence measurements of Hc2 for the thinnest samples.The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg-Landau theory.Interestingly,the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to Tc for the ultra-thin samples.We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity.We further propose the temperature dependence of perpendicular Hc2 as a measure of uniformity of superconducting ultra-thin films.For the thick samples,we find that Hc2 shows maxima for both parallel and perpendicular orientations.The Hc2 peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films.The presence of columnar structure is confirmed by transmission electron microscopy(TEM).In addition,we have measured the angular dependence of magneto-resistance,and the results are consistent with the Hc2 data.展开更多
Individual superatoms are assembled into more complicated nanostructures to diversify their physical properties.Magnetism of assembled superatoms remains,however,ambiguous,particularly in terms of its distance depende...Individual superatoms are assembled into more complicated nanostructures to diversify their physical properties.Magnetism of assembled superatoms remains,however,ambiguous,particularly in terms of its distance dependence.Here,we report density functional theory calculations on the distance-dependent magnetism of transition metal embedded Au_(6)Te_(8)Se_(12)(ATS)superatomic dimers.Among the four considered transition metals,which include V,Cr,Mn and Fe,the Cr-embedded Au_(6)Te_(12)Se_(8)(Cr@ATS)is identified as the most suitable for exploring the inter-superatomic distancedependent magnetism.We thus focused on Cr@ATS superatomic dimers and found an inter-superatomic magnetizationdistance oscillation where three transitions occur for magnetic ordering and/or anisotropy at different inter-superatomic distances.As the inter-superatomic distance elongates,a ferromagnetism(FM)-to-antiferromagnetic(AFM)transition and a sequential AFM-to-FM transition occur,ascribed to competitions among Pauli repulsion and kinetic-energy-gains in formed inter-superatomic Cr-Au-Au-Cr covalent bonds and Te-Te quasi-covalent bonds.For the third transition,in-plane electronic hybridization contributes to the stabilization of the AFM configuration.This work unveils two mechanisms for tuning magnetism through non-covalent interactions and provides a strategy for manipulating magnetism in superatomic assemblies.展开更多
Low-dimensional physics provides profound insights into strongly correlated interactions,leading to enhancedquantum effects and the emergence of exotic quantum states.The Ln_(3)ScBi_(5)family stands out as a chemicall...Low-dimensional physics provides profound insights into strongly correlated interactions,leading to enhancedquantum effects and the emergence of exotic quantum states.The Ln_(3)ScBi_(5)family stands out as a chemicallyversatile kagome platform with mixed low-dimensional structural framework and tunable physical properties.Ourresearch initiates with a comprehensive evaluation of the currently known Ln_(3)ScBi_(5)(Ln=La-Nd,Sm)materials,providing a robust methodology for assessing their stability frontiers within this system.Focusing on Pr_(3)ScBi_(5),we investigate the influence of the zigzag chains of quasi-one-dimensional(Q1D)motifs and the distorted kagomelayers of quasi-two-dimensional(Q2D)networks in the mixed-dimensional structure on the intricate magneticground states and unique spin fluctuations.Our study reveals that the noncollinear antiferromagnetic(AFM)moments of Pr^(3+)ions are confined within the Q2D kagome planes,displaying minimal in-plane anisotropy.Incontrast,a strong AFM coupling is observed within the Q1D zigzag chains,significantly constraining spin motion.Notably,magnetic frustration is partially a consequence of coupling to conduction electrons via Ruderman-Kittel-Kasuya-Yosida interaction,highlighting a promising framework for future investigations into mixed-dimensional frustration in Ln_(3)ScBi_(5) systems.展开更多
Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). T...Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). To date, their PCE values are comparable to the established photovoltaic technologies such as crystalline silicon. Intensive research activities associated with PSCs have been being performed,since 2009, aiming to further boost the device performance in terms of efficiency and stability via different strategies in order to accelerate the progress of commercialization. The emerging 2 D black phosphorus(BP) is a novel class of semiconducting material owing to its unique characteristics, allowing them to become attractive materials for applications in a variety of optical and electronic devices, which have been comprehensively reviewed in the literature. However, comprehensive reviews focusing on the application of BP in PSCs are scarce in the community. This review discusses the research works with the incorporation of BP as a functional material in PSCs. The methodology as well as the effects of employing BP in different regions of PSCs are summarized. Further challenges and potential research directions are also highlighted.展开更多
Few-layer two-dimensional(2D)semiconductor nanosheets with a layer-dependent band gap are attractive building blocks for large-area thin-film electronics.A general approach is developed to fast prepare uniform and pha...Few-layer two-dimensional(2D)semiconductor nanosheets with a layer-dependent band gap are attractive building blocks for large-area thin-film electronics.A general approach is developed to fast prepare uniform and phase-pure 2HWSe2 semiconducting nanosheets at a large scale,which involves the supercritical carbon dioxide(SC-CO2)treatment and a mild sonication-assisted exfoliation process in aqueous solution.The as-prepared 2H-WSe2 nanosheets preserve the intrinsic physical properties and intact crystal structures,as confirmed by Raman,x-ray photoelectron spectroscopy(XPS),and scanning transmission electron microscope(STEM).The uniform 2H-WSe2 nanosheets can disperse well in water for over six months.Such good dispersivity and uniformity enable these nanosheets to self-assembly into thickness-controlled thin films for scalable fabrication of large-area arrays of thin-film electronics.The electronic transport and photoelectronic properties of the field-effect transistor based on the self-assembly 2H-WSe2 thin film have also been explored.展开更多
Converting CO_(2) emissions to valuable carbonaceous chemicals/fuels under mild conditions provides a sustainable way to maintain carbon balance and alleviate the energy shortage.Low‐dimensional material(LDM)supporte...Converting CO_(2) emissions to valuable carbonaceous chemicals/fuels under mild conditions provides a sustainable way to maintain carbon balance and alleviate the energy shortage.Low‐dimensional material(LDM)supported single‐atom catalysts(SACs)have been attracted significant attention for electrochemical CO_(2) reduction reaction(ECR)in recent years.This is mainly because integrating the single‐atoms and LDMs can inherit the advantages of themselves and the synergy effects between them are potential to enhance the ECR performance.In this review,we summarized the strategies for synthesizing LDM supported SACs for ECR,and different LDM supported SACs for ECR have been briefly introduced.Moreover,some optimization strategies for LDM supported SACs towards CO_(2) electroreduction are highlighted.At the end of this review,the perspectives and challenges of LDM supported SACs for ECR are provided.展开更多
Three-dimensional metal-halide perovskites have emerged as promising light harvesting materials for converting sunlight to electricity in the last few years.High power conversion efficiency of 23.3%has been demonstrat...Three-dimensional metal-halide perovskites have emerged as promising light harvesting materials for converting sunlight to electricity in the last few years.High power conversion efficiency of 23.3%has been demonstrated.However,the main challenge that currently limits the application of the perovskite solar cells is the long-term stability,which has ambient,thermal,and photo stability weaknesses.展开更多
Simulating incident group wave with narrow spectrum by nonlinear slowly modulated Stoking wave train and using Multiple Scales Method.problem of the second-order low frequency diffraction of group waves on a two-di me...Simulating incident group wave with narrow spectrum by nonlinear slowly modulated Stoking wave train and using Multiple Scales Method.problem of the second-order low frequency diffraction of group waves on a two-di mensionai floating body has been studied.The first-order and second-order low frequency diffraction potentials are derived,which lead to the second-order and third-order low frequency forces respectively.It is shown thai the sec- ond-order low frequency force generated by first-order low frequency diffraction potentials is verticcal to undis- turbed free surface,and is directly proportional to square of envelope amplitude of incident wave and to waterline width of floating body.The horizontal low frequency forces are caused by the second-order low frequency diffrac- tion potential.To determine it only two linear boundary value problems are necessary to be solved.展开更多
Excitons,which are bound states consisting of electron-hole pairs,have garnered significant attention in condensed matter physics research over the past decade.Due to the key characteristics of charge neutrality,mobil...Excitons,which are bound states consisting of electron-hole pairs,have garnered significant attention in condensed matter physics research over the past decade.Due to the key characteristics of charge neutrality,mobility,and photoelectric conversion,excitons have diverse applications in technologies,such as transistors,photodetectors,light-emitting diodes,and solar cells.The optical method has been commonly used to study excitons in semiconductors,but it falls short in providing momentum information.Consequently,angle-resolved photoemission spectroscopy(ARPES)has gained attention in recent years for its ability to offer direct insights into momentum space.This article reviews the recent progress of ARPES in the study of excitons in quantum materials,focusing on both stimulated and spontaneous excitons.For stimulated excitons in semiconductors,we review research involving two-photon time-resolved ARPES techniques,which detect exciton bound states directly within the semiconductor band gap,as well as single-photon ARPES studies that excite stimulated excitons manifested as side energy bands between conduction bands and valence bands.Regarding spontaneous excitons,we review ARPES studies that have been crucial in revealing the physical properties of excitons condensation and band folding effects.Finally,we offer a perspective on future research directions in this field.展开更多
Single-photon detections(SPDs)represent a highly sensitive light detection technique capable of detecting individual photons at extremely low light intensity levels.This technology mainly relies on the mainstream SPDs...Single-photon detections(SPDs)represent a highly sensitive light detection technique capable of detecting individual photons at extremely low light intensity levels.This technology mainly relies on the mainstream SPDs,such as photomultiplier tubes(PMTs),avalanche photodiodes(SAPD),superconducting nanowire single-photon detectors(SNSPDs),supercon-ducting transition-edge sensor(TES),and hybrid lead halide perovskite.However,the complexity and high manufacturing cost,coupled with the requirement of special conditions like a low-temperature environment,pose significant challenges to the wide adoption of SPDs.To address the challenges faced by SPDs,significant efforts have been devoted to enhan-cing their performance.In this review,we first summarize the principles and technical challenges of several SPDs.Conductors,superconductors,semiconductors,3D bulk materials,2D film materials,1D nanowires,and OD quantum dots have all been discussed for single-photon detectors.Methods such as special optical structure,waveguide integration,and strain engineering have been employed to elevate the performance of single-photon detectors.These techniques enhance light absorption and modulate the band structure of the material,thereby improving the single-photon sensitivity.By providing an overview of the current situation and future challenges of SPDs,this review aims to propose potential solutions for photon detection technology.展开更多
基金financially supported by the National Basic Research Program of China,Fundamental Studies of Perovskite Solar Cells(Grant 2015CB932200)the Natural Science Foundation of China(Grant 51035063)+2 种基金Natural Science Foundation of Jiangsu Province,China(Grants 55135039 and 55135040)Jiangsu Specially-Appointed Professor program(Grant 54907024)Startup from Nanjing Tech University(Grants 3983500160,3983500151,and 44235022)
文摘Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, low dimensional perovskites suffer fl＇om low power conversion efficiency （PCE） with respect to their three dimensional analogues. Therefore, it is imperative to find excellent low-dimensional perovskite materials for improving the PCE. Previous work has demonstrated that bulkier organic molecules, e,g., C6Hs（CH2）2NH3＋ （PEA＋）, CH3（CH2）3NH3＋（n-BAT, iso-BA＋）, C2H4NH3 ＋, and polyethylenimine cations （PEI＋）, play an important role in the formation of low-dimensional perovskites. In this review, we review the recent development of low dimensional perovskites for solar cells application in terms of film preparation, photophysics, and stability of perovskites, as well as the related device structure and physics. We have also discussed the future development of low-dimensional perovskites from materials design, fabri- cation processes, and device structure.
基金supported by National Natural Science Foundation of China(Grant No.41874146 and No.42030103)Postgraduate Innovation Project of China University of Petroleum(East China)(No.YCX2021012)
文摘Seismic data reconstruction is an essential and yet fundamental step in seismic data processing workflow,which is of profound significance to improve migration imaging quality,multiple suppression effect,and seismic inversion accuracy.Regularization methods play a central role in solving the underdetermined inverse problem of seismic data reconstruction.In this paper,a novel regularization approach is proposed,the low dimensional manifold model(LDMM),for reconstructing the missing seismic data.Our work relies on the fact that seismic patches always occupy a low dimensional manifold.Specifically,we exploit the dimension of the seismic patches manifold as a regularization term in the reconstruction problem,and reconstruct the missing seismic data by enforcing low dimensionality on this manifold.The crucial procedure of the proposed method is to solve the dimension of the patches manifold.Toward this,we adopt an efficient dimensionality calculation method based on low-rank approximation,which provides a reliable safeguard to enforce the constraints in the reconstruction process.Numerical experiments performed on synthetic and field seismic data demonstrate that,compared with the curvelet-based sparsity-promoting L1-norm minimization method and the multichannel singular spectrum analysis method,the proposed method obtains state-of-the-art reconstruction results.
文摘The characterization of microstructure for three kinds of typical low dimensional materials,such as ultrafine particle(zero- dimension),whisker(one- dimension)and thin film(two-dimensions),has been carried out.The methods and criteria for the characterization are investigated and introduced.Some interesting results of the characterization are reported.
基金supported by funding from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany's Excellence Strategy-EXC 2089/1-390776260(e-conversion)via the International Research Training Group 2022 Alberta/Technical University of Munich International Graduate School for Environmentally Responsible Functional Hybrid Materials(ATUMS).
文摘With the exponential growth of the internet of things,artificial intelligence,and energy-efficient high-volume data digital communications,there is an urgent demand to develop new information technologies with high storage capacity.This needs to address the looming challenge of conventional Von Neumann architecture and Moore's law bottleneck for future data-intensive computing applications.A promising remedy lies in memristors,which offer distinct advantages of scalability,rapid access times,stable data retention,low power consumption,multistate storage capability and fast operation.Among the various materials used for active layers in memristors,low dimensional perovskite semiconductors with structural diversity and superior stability exhibit great potential for next generation memristor applications,leveraging hysteresis characteristics caused by ion migration and defects.In this review the progress of low-dimensional perovskite memory devices is comprehensively summarized.The working mechanism and fundamental processes,including ion migration dynamics,charge carrier transport and electronic resistance that underlies the switching behavior of memristors are discussed.Additionally,the device parameters are analyzed with special focus on the effective methods to improve electrical performance and operational stability.Finally,the challenges and perspective on major hurdles of low-dimensional perovskite memristors in the expansive application domains are provided.
文摘In this review, we present a summary of some recent experiments on topological insulators （TIs） and superconducting nanowires and fihns. Electron electron interaction （EEI）, weak anti-localization （WAL） and anisotropic magneto-resistance （AMR） effect fbund in topological insulator fihns by transport measurements are reported. Then, transport properties of superconducting films, bridges and nanowires and proximity effect in non-superconducting nanowires are described. Finally, the interplay between topological insulators and superconductors （SCs） is also discussed.
基金the National Natural Science Foundation of China(62174079)Science,Technology and Innovation Commission of Shenzhen Municipality(Projects Nos.JCYJ20220530113015035,JCYJ20210324120204011 and KQTD2015071710313656).
文摘Recently,the development of materials with circularly polarized luminescence(CPL)has attracted numerous attentions owing to their potential applications in various fields.Among diverse mechanisms for the origin of chiroptical properties in low dimensional semiconductors(LDS),the self-assembly approach provides a powerful technique for acquisition of strong chiroptical activity.Benefiting from this approach,LDS could be endowed with CPL in which the dissymmetry factor,a vital parameter for evaluating the performance of CPL,could be greatly improved.In this review,state-of-the-art of selfassembled LDS will be summarized.The current challenges and perspectives in this emerging field are also presented.This review could not only provide insights of the fundamentals of self-assembled chirality,but also shine light for designing CPL-active functional nanomaterials toward their applications based on novel optoelectronic devices.
文摘Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimen- sion. In this paper, local-geometric-projection method is applied to obtain fow dimensional element from various target radiating noise and the derived phase portraits show obviously low dimensional attractors. Furthermore, attractor dimension and cross prediction error are used for classification. It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.
基金supported by the National Natural Science Foundation of China(No.61074131,91132722)the Doctoral Fund of the Ministry of Education of China(20101202110007).
文摘Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multichannel spike trains were recorded in rat prefrontal cortex during a work memory task in Y-maze.As discretesignals,spikes were transferred into cont inuous signals by estinating entropy.Then the normalized continuous signals were decomposed via non-negative sparse met hod.The non-negative components were extracted to reconstruct a low-dimensional ensemble,while none of the feature components were missed.The results showed that,for well-trained rats,neuronal ensemble activities in the prefrontal cortex changed dynamically during the.working memory task.And the neuronal ensemble is more explicit via using non-negative sparse coding.Our results indicate that the neuronal ensemblesparse coding method can effectively reduce the dimnension of neuronal activity and it is a useful tool to express neural coding.
文摘In this paper we analyze a long standing problem of the appearance of spurious,non-physical solutions arising in the application of the effective mass theory to low dimensional nanostructures.The theory results in a system of coupled eigenvalue PDEs that is usually supplemented by interface boundary conditions that can be derived from a variational formulation of the problem.We analyze such a system for the envelope functions and show that a failure to restrict their Fourier expansion coeffi-cients to small k components would lead to the appearance of non-physical solutions.We survey the existing methodologies to eliminate this difficulty and propose a simple and effective solution.This solution is demonstrated on an example of a two-band model for both bulk materials and low-dimensional nanostructures.Finally,based on the above requirement of small k,we derive a model for nanostructures with cylindrical symmetry and apply the developed model to the analysis of quantum dots using an eight-band model.
文摘This special issue will include reviews,regular papers,and short communications,and reports in the fields for next generation electronics and photonics.The topics include but not restricted in advanced microelectronic devices and materials,low-dimensional materials and novel nanodevice applications,flexible/wearable/implantable electronics,wide bandgap semiconductor materials and devices,photoelectronics,photonics,advanced display technologies,nanophotonics,integrated quantum photonics,photovoltaics,energy harvesting and self-powered wireless sensing,sensors,micro-actuators,MEMS,microfluidics,and bioMEMS,etc.
基金the Chinese Academy of Sciences(Grant No.XDB25000000).
文摘We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper critical field(Hc2)in parallel to surface orientation shows bending curvature close to critical temperature Tc,suggesting a two-dimensional(2D)nature of the samples.The 2D behavior is further supported by the angular dependence measurements of Hc2 for the thinnest samples.The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg-Landau theory.Interestingly,the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to Tc for the ultra-thin samples.We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity.We further propose the temperature dependence of perpendicular Hc2 as a measure of uniformity of superconducting ultra-thin films.For the thick samples,we find that Hc2 shows maxima for both parallel and perpendicular orientations.The Hc2 peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films.The presence of columnar structure is confirmed by transmission electron microscopy(TEM).In addition,we have measured the angular dependence of magneto-resistance,and the results are consistent with the Hc2 data.
基金financial support from the National Key R&D Program of China(Grant No.2023YFA1406500)the National Natural Science Foundation of China(Grant Nos.11974422,12104504,and 12204534)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.22XNKJ30)。
文摘Individual superatoms are assembled into more complicated nanostructures to diversify their physical properties.Magnetism of assembled superatoms remains,however,ambiguous,particularly in terms of its distance dependence.Here,we report density functional theory calculations on the distance-dependent magnetism of transition metal embedded Au_(6)Te_(8)Se_(12)(ATS)superatomic dimers.Among the four considered transition metals,which include V,Cr,Mn and Fe,the Cr-embedded Au_(6)Te_(12)Se_(8)(Cr@ATS)is identified as the most suitable for exploring the inter-superatomic distancedependent magnetism.We thus focused on Cr@ATS superatomic dimers and found an inter-superatomic magnetizationdistance oscillation where three transitions occur for magnetic ordering and/or anisotropy at different inter-superatomic distances.As the inter-superatomic distance elongates,a ferromagnetism(FM)-to-antiferromagnetic(AFM)transition and a sequential AFM-to-FM transition occur,ascribed to competitions among Pauli repulsion and kinetic-energy-gains in formed inter-superatomic Cr-Au-Au-Cr covalent bonds and Te-Te quasi-covalent bonds.For the third transition,in-plane electronic hybridization contributes to the stabilization of the AFM configuration.This work unveils two mechanisms for tuning magnetism through non-covalent interactions and provides a strategy for manipulating magnetism in superatomic assemblies.
基金supported by the National Key R&D Program of China(Grant Nos.2024YFA1408400 and 2021YFA1400401)the National Natural Science Foundation of China(Grant Nos.U22A6005 and 52271238)+2 种基金the China Postdoctoral Science Foundation(Grant No.2025M770186)the Center for Materials Genome,and the Synergetic Extreme Condition User Facility(SECUF)supported by the AI-driven experiments,simulations and model training on the robotic AI-Scientist platform from Chinese Academy of Sciences and the Research Funds for the Central Universities(Grant No.N25ZLE007).
文摘Low-dimensional physics provides profound insights into strongly correlated interactions,leading to enhancedquantum effects and the emergence of exotic quantum states.The Ln_(3)ScBi_(5)family stands out as a chemicallyversatile kagome platform with mixed low-dimensional structural framework and tunable physical properties.Ourresearch initiates with a comprehensive evaluation of the currently known Ln_(3)ScBi_(5)(Ln=La-Nd,Sm)materials,providing a robust methodology for assessing their stability frontiers within this system.Focusing on Pr_(3)ScBi_(5),we investigate the influence of the zigzag chains of quasi-one-dimensional(Q1D)motifs and the distorted kagomelayers of quasi-two-dimensional(Q2D)networks in the mixed-dimensional structure on the intricate magneticground states and unique spin fluctuations.Our study reveals that the noncollinear antiferromagnetic(AFM)moments of Pr^(3+)ions are confined within the Q2D kagome planes,displaying minimal in-plane anisotropy.Incontrast,a strong AFM coupling is observed within the Q1D zigzag chains,significantly constraining spin motion.Notably,magnetic frustration is partially a consequence of coupling to conduction electrons via Ruderman-Kittel-Kasuya-Yosida interaction,highlighting a promising framework for future investigations into mixed-dimensional frustration in Ln_(3)ScBi_(5) systems.
基金the Scientific Research Grant from Ministry of Education and Science of the Republic of Kazakhstan(AP08856931)the Nazarbayev University(110119FD4506,021220CRP0422)。
文摘Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). To date, their PCE values are comparable to the established photovoltaic technologies such as crystalline silicon. Intensive research activities associated with PSCs have been being performed,since 2009, aiming to further boost the device performance in terms of efficiency and stability via different strategies in order to accelerate the progress of commercialization. The emerging 2 D black phosphorus(BP) is a novel class of semiconducting material owing to its unique characteristics, allowing them to become attractive materials for applications in a variety of optical and electronic devices, which have been comprehensively reviewed in the literature. However, comprehensive reviews focusing on the application of BP in PSCs are scarce in the community. This review discusses the research works with the incorporation of BP as a functional material in PSCs. The methodology as well as the effects of employing BP in different regions of PSCs are summarized. Further challenges and potential research directions are also highlighted.
基金National Natural Science Foundation of China(Grant Nos.51771224,51772087,and 51471185)the National Key R&D Program of China(Grant Nos.2016YFJC020013 and 2018FYA0305800)Fujian Institute of Innovation,Chinese Academy of Sciences.
文摘Few-layer two-dimensional(2D)semiconductor nanosheets with a layer-dependent band gap are attractive building blocks for large-area thin-film electronics.A general approach is developed to fast prepare uniform and phase-pure 2HWSe2 semiconducting nanosheets at a large scale,which involves the supercritical carbon dioxide(SC-CO2)treatment and a mild sonication-assisted exfoliation process in aqueous solution.The as-prepared 2H-WSe2 nanosheets preserve the intrinsic physical properties and intact crystal structures,as confirmed by Raman,x-ray photoelectron spectroscopy(XPS),and scanning transmission electron microscope(STEM).The uniform 2H-WSe2 nanosheets can disperse well in water for over six months.Such good dispersivity and uniformity enable these nanosheets to self-assembly into thickness-controlled thin films for scalable fabrication of large-area arrays of thin-film electronics.The electronic transport and photoelectronic properties of the field-effect transistor based on the self-assembly 2H-WSe2 thin film have also been explored.
基金National Key R&D Program of China,Grant/Award Number:2018YFA0702003National Natural Science Foundation of China,Grant/Award Numbers:21871159,21890383+1 种基金Science and Technology Key Project of Guangdong Province of China,Grant/Award Number:2020B010188002Fellowship of China Postdoctoral Science Foundation,Grant/Award Number:2020M680505。
文摘Converting CO_(2) emissions to valuable carbonaceous chemicals/fuels under mild conditions provides a sustainable way to maintain carbon balance and alleviate the energy shortage.Low‐dimensional material(LDM)supported single‐atom catalysts(SACs)have been attracted significant attention for electrochemical CO_(2) reduction reaction(ECR)in recent years.This is mainly because integrating the single‐atoms and LDMs can inherit the advantages of themselves and the synergy effects between them are potential to enhance the ECR performance.In this review,we summarized the strategies for synthesizing LDM supported SACs for ECR,and different LDM supported SACs for ECR have been briefly introduced.Moreover,some optimization strategies for LDM supported SACs towards CO_(2) electroreduction are highlighted.At the end of this review,the perspectives and challenges of LDM supported SACs for ECR are provided.
基金The authors acknowledge the financial support from Macao Science and Technology Development Funds(FDCT-116/2016/A3,FDCT-091/2017/A2,FDCT-014/2017/AMJ)Research Grants(SRG2016-00087-FST,MYRG2018-00148-IAPME)from University of Macao,the Natural Science Foundation of China(91733302,61605073,2015CB932200)the Young 1000 Talents Global Recruitment Program of China.
文摘Three-dimensional metal-halide perovskites have emerged as promising light harvesting materials for converting sunlight to electricity in the last few years.High power conversion efficiency of 23.3%has been demonstrated.However,the main challenge that currently limits the application of the perovskite solar cells is the long-term stability,which has ambient,thermal,and photo stability weaknesses.
基金This work is supported by Chinese National Natural Science Foundation
文摘Simulating incident group wave with narrow spectrum by nonlinear slowly modulated Stoking wave train and using Multiple Scales Method.problem of the second-order low frequency diffraction of group waves on a two-di mensionai floating body has been studied.The first-order and second-order low frequency diffraction potentials are derived,which lead to the second-order and third-order low frequency forces respectively.It is shown thai the sec- ond-order low frequency force generated by first-order low frequency diffraction potentials is verticcal to undis- turbed free surface,and is directly proportional to square of envelope amplitude of incident wave and to waterline width of floating body.The horizontal low frequency forces are caused by the second-order low frequency diffrac- tion potential.To determine it only two linear boundary value problems are necessary to be solved.
基金supported by the National Natural Science Foundation of China(Grant Nos.12422405,and 12350710785)the Fundamental Research Funds for the Central Universities(Grant No.226-202400068)+2 种基金the Research Grant Council(RGC)via the Early Career Scheme(ECS)(Grant No.21304023)the Research Grant Council(RGC)(Grant Nos.C6033-22G,C1018-22E,C6046-24GF,and C1002-24Y)partially support by Quantum Science Center of Guangdong-Hong Kong-Macao Great Bay Area。
文摘Excitons,which are bound states consisting of electron-hole pairs,have garnered significant attention in condensed matter physics research over the past decade.Due to the key characteristics of charge neutrality,mobility,and photoelectric conversion,excitons have diverse applications in technologies,such as transistors,photodetectors,light-emitting diodes,and solar cells.The optical method has been commonly used to study excitons in semiconductors,but it falls short in providing momentum information.Consequently,angle-resolved photoemission spectroscopy(ARPES)has gained attention in recent years for its ability to offer direct insights into momentum space.This article reviews the recent progress of ARPES in the study of excitons in quantum materials,focusing on both stimulated and spontaneous excitons.For stimulated excitons in semiconductors,we review research involving two-photon time-resolved ARPES techniques,which detect exciton bound states directly within the semiconductor band gap,as well as single-photon ARPES studies that excite stimulated excitons manifested as side energy bands between conduction bands and valence bands.Regarding spontaneous excitons,we review ARPES studies that have been crucial in revealing the physical properties of excitons condensation and band folding effects.Finally,we offer a perspective on future research directions in this field.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272160,U2330112,and 52002254)the Sichuan Science and Technology Foundation(Grant Nos.2023YFSY0002,2020YJ0262,2021YFH0127,2022YFH0083,and 2022YFSY0045)+1 种基金the Chunhui Plan of Ministry of Education of China,Fundamental Research Funds for the Central Universities,China(Grant No.YJ201893)the Open-Foundation of Key Laboratory of Laser Device Technology,China North Industries Group Corporation Limited(Grant No.LLDT2023-006).
文摘Single-photon detections(SPDs)represent a highly sensitive light detection technique capable of detecting individual photons at extremely low light intensity levels.This technology mainly relies on the mainstream SPDs,such as photomultiplier tubes(PMTs),avalanche photodiodes(SAPD),superconducting nanowire single-photon detectors(SNSPDs),supercon-ducting transition-edge sensor(TES),and hybrid lead halide perovskite.However,the complexity and high manufacturing cost,coupled with the requirement of special conditions like a low-temperature environment,pose significant challenges to the wide adoption of SPDs.To address the challenges faced by SPDs,significant efforts have been devoted to enhan-cing their performance.In this review,we first summarize the principles and technical challenges of several SPDs.Conductors,superconductors,semiconductors,3D bulk materials,2D film materials,1D nanowires,and OD quantum dots have all been discussed for single-photon detectors.Methods such as special optical structure,waveguide integration,and strain engineering have been employed to elevate the performance of single-photon detectors.These techniques enhance light absorption and modulate the band structure of the material,thereby improving the single-photon sensitivity.By providing an overview of the current situation and future challenges of SPDs,this review aims to propose potential solutions for photon detection technology.
