Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs wit...Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.展开更多
In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor depo...In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor deposition method.Photoluminescence measurements indicate the In Ga As nanowires have strong light emission in near-infrared region. For the first time, photodetector based on as-grown In Ga As nanowires was also constructed. It shows good light response over a broad spectral range in infrared region with responsivity of 6.5×10~3 AW^(-1) and external quantum efficiency of 5.04×10~5%. This photodetector may have potential applications in integrated optoelectronic devices and systems.展开更多
The controllable growth of large area band gap engineered-semiconductor nanowires(NWs) with precise orientation and position is of immense significance in the development of integrated optoelectronic devices. In this ...The controllable growth of large area band gap engineered-semiconductor nanowires(NWs) with precise orientation and position is of immense significance in the development of integrated optoelectronic devices. In this study, we have achieved large area in-plane-aligned CdS_xSe_(1-x) nanowires via chemical vapor deposition method. The orientation and position of the alloyed CdS_xSe_(1-x)NWs could be controlled well by the graphoepitaxial effect and the patterns of Au catalyst. Microstructure characterizations of these as-grown samples reveal that the aligned CdS_xSe_(1-x)NWs possess smooth surface and uniform diameter. The aligned CdS_xSe_(1-x)NWs have strong photoluminescence and high-quality optical waveguide emission covering almost the entire visible wavelength range. Furthermore, photodetectors were constructed based on individual alloyed CdS_xSe_(1-x)NWs. These devices exhibit high performance and fast response speed with photoresponsivity ～670 A W^(-1) and photoresponse time ～76 ms. Present work provides a straightforward way to realize in-plane aligned bandgap engineering in semiconductor NWs for the development of large area NW arrays,which exhibit promising applications in future optoelectronic integrated circuits.展开更多
Self-assembled nanostructure arrays integrating the advantages of the intrinsic characters of nanostructure as well as the array stability are appealing in advanced materials.However,the precise bottom-up synthesis of...Self-assembled nanostructure arrays integrating the advantages of the intrinsic characters of nanostructure as well as the array stability are appealing in advanced materials.However,the precise bottom-up synthesis of nanostructure arrays without templates or substrates is quite challenging because of the general occurrence of homogeneous nucleation and the difficult manipulation of noncovalent interactions.Herein,we first report the precisely manipulated synthesis of well-defined louver-like P-doped carbon nitride nanowire arrays(L-PCN)via a supramolecular self-assembly method by regulating the noncovalent interactions through hydrogen bond.With this strategy,CN nanowires align in the outer frame with the separation and spatial location achieving ultrastability and outstanding photoelectricity properties.Significantly,this self-assembly L-PCN exhibits a superior visible light-driven hydrogen evolution activity of 1872.9μmol h^−1 g^−1,rendering a^25.6-fold enhancement compared to bulk CN,and high photostability.Moreover,an apparent quantum efficiency of 6.93%is achieved for hydrogen evolution at 420±15 nm.The experimental results and first-principles calculations demonstrate that the remarkable enhancement of photocatalytic activity of L-PCN can be attributed to the synergetic effect of structural topology and dopant.These findings suggest that we are able to design particular hierarchical nanostructures with desirable performance using hydrogen-bond engineering.展开更多
Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer...Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer is of vital import-ance for guiding the design of functional optoelectronic applications.In this work,type-Ⅱ0D-2D CdSe/ZnS quantum dots/MoS_(2)vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances.From spectral measurements in both steady and transient states,the phenomena of suppressed photolu-minescence(PL)emissions,shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface.A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details,which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10^(13)cm^(−2).The enhanced photoresponses(1.57×10^(4)A·W^(-1))and detectivities(2.86×10^(11)Jones)in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices.These results are expected to inspire the basic understand-ing of interfacial physics at 0D/2D interfaces,and shed the light on promoting the development of mixed-dimensional op-toelectronic devices in the near future.展开更多
In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in ...In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in air. During the measurement, a focused laser was used to heat one end of a freely suspended nanowire, with its other end embedded into a carbon conductive adhesive. In order to obtain the thermal conductivity of In As nanowires, the heat loss in the heat transfer process was estimated, which includes the heat loss through air conduction, the heat convection, and the radiation loss. The absorption ratio of the laser power in the In As nanowire was calculated. The result shows that the thermal conductivity of In As nanowires monotonically increases from 6.4 W m-1K-1to 10.5 W m-1K-1with diameters increasing from 100 nm to 190 nm, which is ascribed to the enhanced phonon-boundary scattering.展开更多
Two-dimensional(2D)magnetic materials have aroused tremendous interest due to the 2D confinement of magnetism and potential applications in spintronic and valleytronic devices.However,most of the currently 2D magnetic...Two-dimensional(2D)magnetic materials have aroused tremendous interest due to the 2D confinement of magnetism and potential applications in spintronic and valleytronic devices.However,most of the currently 2D magnetic materials are achieved by the exfoliation from their bulks,of which the thickness and domain size are difficult to control,limiting the practical device applications.Here,we demonstrate the realization of thickness-tunable rhombohedral Cr_(2)Se_(3)nanosheets on different substrates via the chemical vapor deposition route.The magnetic transition temperature at about 75 K is observed.Furthermore,van der Waals heterostructures consisting of Cr_(2)Se_(3)nanosheets and monolayer WS2 are constructed.We observe the magnetic proximity effect in the heterostructures,which manifests the manipulation of the valley polarization in monolayer WS2.Our work contributes to the vapor growth and applications of 2D magnetic materials.展开更多
Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium s...Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium sulfide(CdS) nanowires are investigated by a customer-built optical holder inside transmission electron microscope, wherein in situ electromechanical resonance took place in conjunction with photo excitation. It is found that the natural resonance frequency of the nanowire under illumination becomes considerably lower than that under darkness. This redshift effect is closely related to the wavelength of the applied light and the diameter of the nanowires. Density functional theory(DFT) calculation shows that the photoexcitation leads to the softening of CdS nanowires and thus the redshift of natural frequency, which is in agreement with the experimental results.展开更多
Due to the large exciton binding energy,two-dimensional(2D)transition metal dichalcogenides(TMDCs)provide an ideal platform for studying excitonic states and related photonics and optoelectronics.Polarization states l...Due to the large exciton binding energy,two-dimensional(2D)transition metal dichalcogenides(TMDCs)provide an ideal platform for studying excitonic states and related photonics and optoelectronics.Polarization states lead to distinct light-matter interactions which are of great importance for device applications.In this work,we study polarized photoluminescence spectra from intralayer exciton and indirect exciton in WS_(2) and WSe_(2) atomic layers,and interlayer exciton in WS_(2)/WSe_(2) heterostructures by radially and azimuthally polarized cylindrical vector laser beams.We demonstrated the same in-plane and out-of-plane polarization behavior from the intralayer and indirect exciton.Moreover,with these two laser modes,we obtained interlayer exciton in WS_(2)/WSe_(2) heterostructures with stronger out-of-plane polarization,due to the formation of vertical electric dipole moment.展开更多
At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγ...At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγandαphases were found to be the most stable phases for monolayer and thicker layers,respectively.Here,we found two novel low-dimensional phases,namely theεandζphases.Theζphase is over 29 meV/Te more stable than the most stable monolayerγphase,and theεphase shows comparable stability with the most stable monolayerγphase.The energetic difference between theζandαphases reduces with respect to the increased layer thickness and vanishes at the four-layer(12-sublayer)thickness,while this thickness increases under change doping.Bothεandζphases are metallic chains and layers,respectively.Theζphase,with very strong interlayer coupling,shows quantum well states in its layer-dependent bandstructures.These results provide significantly insight into the understanding of polytypism in Te few-layers and may boost tremendous studies on properties of various few-layer phases.展开更多
Moirésuperlattices,arising from the controlled twisting of van der Waals homostructures at specific angles,have emerged as a promising platform for quantum emission applications.Concurrently,the manipulation of s...Moirésuperlattices,arising from the controlled twisting of van der Waals homostructures at specific angles,have emerged as a promising platform for quantum emission applications.Concurrently,the manipulation of strain provides a versatile strategy to finely adjust electronic band structures,enhance exciton luminescence efficiency,and establish a robust foundation for two-dimensional quantum light sources.However,the intricate interplay between strain and moirépotential remains partially unexplored.Here,we introduce a meticulously designed fusion of strain engineering and the twisted 2L-WSe_(2)/2L-WSe_(2) homobilayers,resulting in the precise localization of moiréexcitons.Employing low-temperature photoluminescence spectroscopy,we unveil the emergence of highly localized moiré-enhanced emission,characterized by the presence of multiple distinct emission lines.Furthermore,our investigation demonstrates the effective regulation of moirépotential depths through strain engineering,with the potential depths of strained and unstrained regions differing by 91%.By combining both experimental and theoretical approaches,our study elucidates the complex relationship between strain and moirépotential,thereby opening avenues for generating strain-induced moiréexciton single-photon sources.展开更多
The growth of data and Internet of Things challenges traditional hardware,which encounters efficiency and power issues owing to separate functional units for sensors,memory,and computation.In this study,we designed an...The growth of data and Internet of Things challenges traditional hardware,which encounters efficiency and power issues owing to separate functional units for sensors,memory,and computation.In this study,we designed an a-phase indium selenide(a-In_(2)Se_(3))transistor,which is a two-dimensional ferroelectric semiconductor as the channel material,to create artificial optic-neural and electro-neural synapses,enabling cutting-edge processing-in-sensor(PIS)and computing-in-memory(CIM)functionalities.As an optic-neural synapse for low-level sensory processing,the a-In_(2)Se_(3)transistor exhibits a high photoresponsivity(2855 A/W)and detectivity(2.91×10^(14)Jones),facilitating efficient feature extraction.For high-level processing tasks as an electro-neural synapse,it offers a fast program/erase speed of 40 ns/50μs and ultralow energy consumption of 0.37 aJ/spike.An AI vision system using a-In_(2)Se_(3)transistors has been demonstrated.It achieved an impressive recognition accuracy of 92.63%within 12 epochs owing to the synergistic combination of the PIS and CIM functionalities.This study demonstrates the potential of the a-In_(2)Se_(3)transistor in future vision hardware,enhancing processing,power efficiency,and AI applications.展开更多
Transition metal dichalcogenides(TMDCs)are promising candidates for future optoelectronic devices accounting for their high carrier mobility and excellent quantum efficiency.However,the limited light absorption effici...Transition metal dichalcogenides(TMDCs)are promising candidates for future optoelectronic devices accounting for their high carrier mobility and excellent quantum efficiency.However,the limited light absorption efficiency in atomically thin layers significantly hinders photocarrier generation,thereby impairing the optoelectronic performance and hindering practical applications.Herein,we successfully synthesized In_(2)Se_(3)/WSe_(2) heterostructures through a typical two-step chemical vapor deposition(CVD)method.The In_(2)Se_(3) nanosheet with strong light absorption capability,serving as the light absorption layer,was integrated with the monolayer WSe_(2),enhancing the photosensitivity of WSe_(2) significantly.Upon laser irradiation with a wavelength of 520 nm,the In_(2)Se_(3)/WSe_(2) heterostructure device shows an ultrahigh photoresponsivity with a value as high as 2333.5 A/W and a remarkable detectivity reaching up to 6.7×10^(12) Jones,which is the highest among almost the reported TMDCs-based heterostructures grown via CVD even some fabricated by mechanical exfoliation(ME).Combing the advantages of CVD method such as large scale,high yield,and clean interface,the In_(2)Se_(3)/WSe_(2) heterostructures would provide a novel path for future high-performance optoelectronic device.展开更多
Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectatio...Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectation.Herein,we demonstrate a competitive assembling strategy for the construction of metal-free graphite carbon nitride(CN)homojunctions in which morphology and composition can be easily controlled simultaneously by only changing the ratio of assembly raw materials.These homojunctions are comprised of porous nanotubular S-doped CN(SCN)grafted with CN nanovesicles,which are derived from thermal polycondensation of melamine-thiocyanuric acid(M-T)/melamine-cyanuric acid(M-C)supramolecular hybrid blocks.This unique architecture and component engineering endows the novel SCN-CN homojunction with abundant active sites,enhanced visible trapping ability,and intimate interface contact.As a result,the synthesized SCN-CN homojunctions demonstrate high photocatalytic activity for hydrogen evolution and pollutant degradation.This developed strategy opens up intriguing opportu-nities for the rational construction of intricate metal-free heterostructures with controllable architecture and interfacial contact for applications in energy-related fields.展开更多
Stretchable electronics have found widespread applications in various fields such as wearable electronics,soft robots,and bioelectronics.As an important promising alternative of traditional rigid conductors,liquid met...Stretchable electronics have found widespread applications in various fields such as wearable electronics,soft robots,and bioelectronics.As an important promising alternative of traditional rigid conductors,liquid metals have demonstrated immense potential to provide high conductivity and stretchability for the stretchable electronic systems.However,limited by their fluidity and high surface tension,challenges remain in achieving liquid metal patterns with low-cost,high-precision,large-scale,and complex geometry.Here,a fabrication technique was proposed based on laser-induced graphene(LIG)stamps to enable liquid metal self-selectively adhere to substrates.Liquid metal patterns could thus be achieved in different designed geometries and could be transferred onto stretchable substrates.The liquid metal patterns exhibit exceptional electrical conductivity(3.24×10^(6)S/m even under 1000%strain),high stretchability(1000%strain,maximum of 2500%),small resistance changes under significant deformations(with a quality factor of 62.5 under 1000%strain),and high resolution(down to 50μm).Utilizing the patterned liquid metals,a stretchable integrated multifunctional optoelectronic system was demonstrated,encompassing a stretchable display matrix,a pressure sensor array,a wireless powering coil,and cardiovascular sensors,which further highlight the remarkable application potential of liquid metals in optoelectronic user-interaction and advanced physiological monitoring.展开更多
Electron-trapping materials,due to their exceptional ability of energy storage and controllable photon release under external stimulation,have attracted considerable attention in the field of optical information stora...Electron-trapping materials,due to their exceptional ability of energy storage and controllable photon release under external stimulation,have attracted considerable attention in the field of optical information storage(OIS).In this work,Gd_(3)Al_(3)Ga_(2)O_(12):Ce^(3+), Yb^(3+)fluorescent ceramics,were developed using air and vacuum sintering technology.By co-doping Ce^(3+)and Yb^(3+),the trap density was significantly increased by 7.5 times compared to samples containing only Ce^(3+).Vacuum annealing further enhanced trap density by 1.6 times compared to samples sintered solely in air,while generating deep traps(1.44 eV),making Gd_(3)Al_(3)Ga_(2)O_(12):Ce^(3+), Yb^(3+) an excellent OIS medium.This work is expected to facilitate the development of OIS materials.展开更多
Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and ...Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and compactness of hybrid perovskite are key factors affecting the performance of photoelectric devices.The photocurrent and photoresponsivity of these devices are relatively low because of the rapidly recombined photoexcited electron-hole pairs in hybrid perovskite.Herein,we develop a facile two-step chemical vapor deposition(CVD)method to synthesize a high-quality van der Waals(vd Ws)MAPb I3/graphene heterostructure for high-performance image sensor.We introduced inorganic sources(PbI2)to vd Ws epitaxially grown Pb I2 film on a seamless graphene monolayer film template through CVD.Methylammonium iodide(MAI)was then reintroduced to prepare the vd Ws MAPb I3/graphene heterostructure.The MAPb I3 layer is composed of densely packed,large-size grains and displays a smooth surface.High photoresponsivity of 107A/W is achieved in the corresponding photodetector.Inspired by the human visual system,we designed a flexible photodetector array containing(24?24)pixels,achieving perfect image recognition and color discrimination.Our study may greatly facilitate the construction of high-performance optoelectronic devices in artificial retina,biomedical imaging,remote sensing,and optical communication.展开更多
Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perf...Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perform machine learning tasks through linear optical transformations.However,the existing architectures often comprise bulky components and,most critically,they cannot mimic the human brain for multitasking.Here,we demonstrate a multi-skilled diffractive neural network based on a metasurface device,which can perform on-chip multi-channel sensing and multitasking in the visible.The polarization multiplexing scheme of the subwavelength nanostructures is applied to construct a multi-channel classifier framework for simultaneous recognition of digital and fashionable items.The areal density of the artificial neurons can reach up to 6.25×10^(6)mm^(-2) multiplied by the number of channels.The metasurface is integrated with the mature complementary metal-oxide semiconductor imaging sensor,providing a chip-scale architecture to process information directly at physical layers for energy-efficient and ultra-fast image processing in machine vision,autonomous driving,and precision medicine.展开更多
High-performance multiphoton-pumped lasers based on cesium lead halide perovskite nanostructures are promising for nonlinear optics and practical frequency upconversion devices in integrated photonics. However, the pe...High-performance multiphoton-pumped lasers based on cesium lead halide perovskite nanostructures are promising for nonlinear optics and practical frequency upconversion devices in integrated photonics. However, the performance of such lasers is highly dependent on the quality of the material and cavity, which makes their fabrication challenging. Herein, we demonstrate that cesium lead halide perovskite triangular nanorods fabricated via vapor methods can serve as gain media and effective cavities for multiphoton-pumped lasers. We observed blue-shifts of the lasing modes in the excitation fluence-dependent lasing spectra at increased excitation powers, which fits well with the dynamics of Burstein-Moss shifts caused by the band filling effect. Moreover, efficient multiphoton lasing in CsPbBr3 nanorods can be realized in a wide excitation wavelength range （700-1,400 nm）. The dynamics of multiphoton lasing were investigated by time-resolved photoluminescence spectroscopy, which indicated that an electron-hole plasma is responsible for the multiphoton-pumped lasing. This work could lead to new opportunities and applications for cesium lead halide perovskite nanostructures in frequency upconversion lasing devices and optical interconnect systems.展开更多
Lead halide perovskites have received tremendous attentions recently for their excellent properties such as high light absorption coefficient and long charge carrier diffusion length. However, the stability issues and...Lead halide perovskites have received tremendous attentions recently for their excellent properties such as high light absorption coefficient and long charge carrier diffusion length. However, the stability issues and the existence of toxic lead cations have largely limited their applications in optoelectronic area. Herein, we report the synthesis and investigation of highly stable and lead-free Cs3Bi2I9 perovskite nanoplates for visible light photodetection applications. The Cs3Bi2I9 nanoplates were synthesized through a facile solution-processed method, which is also applicable to various substrates. The achieved nanoplates present very good crystal quality and exhibit excellent long-term stability even exposed in moist air for several months. Photodetectors were constructed based on these high-quality perovskite nanoplates for the first time, and display a maximum photoresponsivity of 33.1 mA/W under the illumination of 450 nm laser, which is six times higher than the solution-synthesized CH3NH3PbI3 nanowire photodetectors. The specific detectivity of these devices can reach up to 10^10 Jones. Additionally, the devices exhibit fast rise and decay time of 10.2 and 37.2 ms, respectively, and highly stable photoswitching behavior with their photoresponse well retaining under alternating light and darkness. This work opens up a new opportunity for stable and low-toxic perovskite-based optoelectronic applications.展开更多
基金Project supported by the National Key R&D Program of China (Grant No.2022YFA1204302)the National Natural Science Foundation of China (Grant Nos.52022029,52221001,92263107,U23A20570,62090035,U19A2090,and 12174098)+1 种基金the Hunan Provincial Natural Science Foundation of China (Grant Nos.2022JJ30142 and 2019XK2001)in part supported by the State Key Laboratory of Powder Metallurgy,Central South University。
文摘Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.
基金the NSF of China(Nos.61574054,61505051,11374092,11204073,61474040,and51302077)the National Basic Research Program of China(No.2012CB932703)+2 种基金the Hunan province science and technology plan(No.2014FJ2001,2014GK3015,and 2014TT1004)the Hunan Provincial Natural Science Foundation of China(No.2015JJ3049)the Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
文摘In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor deposition method.Photoluminescence measurements indicate the In Ga As nanowires have strong light emission in near-infrared region. For the first time, photodetector based on as-grown In Ga As nanowires was also constructed. It shows good light response over a broad spectral range in infrared region with responsivity of 6.5×10~3 AW^(-1) and external quantum efficiency of 5.04×10~5%. This photodetector may have potential applications in integrated optoelectronic devices and systems.
基金the NSF of China (Nos.51525202,61574054,61635001,61505051,and 51772088)the Hunan province science and technology plan (Nos.2014FJ2001 and 2014TT1004)+1 种基金the Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincethe Fundamental Research Funds for the Central Universities
文摘The controllable growth of large area band gap engineered-semiconductor nanowires(NWs) with precise orientation and position is of immense significance in the development of integrated optoelectronic devices. In this study, we have achieved large area in-plane-aligned CdS_xSe_(1-x) nanowires via chemical vapor deposition method. The orientation and position of the alloyed CdS_xSe_(1-x)NWs could be controlled well by the graphoepitaxial effect and the patterns of Au catalyst. Microstructure characterizations of these as-grown samples reveal that the aligned CdS_xSe_(1-x)NWs possess smooth surface and uniform diameter. The aligned CdS_xSe_(1-x)NWs have strong photoluminescence and high-quality optical waveguide emission covering almost the entire visible wavelength range. Furthermore, photodetectors were constructed based on individual alloyed CdS_xSe_(1-x)NWs. These devices exhibit high performance and fast response speed with photoresponsivity ～670 A W^(-1) and photoresponse time ～76 ms. Present work provides a straightforward way to realize in-plane aligned bandgap engineering in semiconductor NWs for the development of large area NW arrays,which exhibit promising applications in future optoelectronic integrated circuits.
基金the National Natural Science Foundation of China(Nos.51772085 and U1830138)Hunan Provincial Innovation Foundation for Postgraduate(No.CX20190311)
文摘Self-assembled nanostructure arrays integrating the advantages of the intrinsic characters of nanostructure as well as the array stability are appealing in advanced materials.However,the precise bottom-up synthesis of nanostructure arrays without templates or substrates is quite challenging because of the general occurrence of homogeneous nucleation and the difficult manipulation of noncovalent interactions.Herein,we first report the precisely manipulated synthesis of well-defined louver-like P-doped carbon nitride nanowire arrays(L-PCN)via a supramolecular self-assembly method by regulating the noncovalent interactions through hydrogen bond.With this strategy,CN nanowires align in the outer frame with the separation and spatial location achieving ultrastability and outstanding photoelectricity properties.Significantly,this self-assembly L-PCN exhibits a superior visible light-driven hydrogen evolution activity of 1872.9μmol h^−1 g^−1,rendering a^25.6-fold enhancement compared to bulk CN,and high photostability.Moreover,an apparent quantum efficiency of 6.93%is achieved for hydrogen evolution at 420±15 nm.The experimental results and first-principles calculations demonstrate that the remarkable enhancement of photocatalytic activity of L-PCN can be attributed to the synergetic effect of structural topology and dopant.These findings suggest that we are able to design particular hierarchical nanostructures with desirable performance using hydrogen-bond engineering.
基金This work is supported by National Natural Science Foundation of China(No.92163135,11904098,51972105,U19A2090 and 62090035)Hunan Provincial Natural Science Foundation of China(No.2019JJ30004)+1 种基金Hunan International Innovation Cooperation Platform(No.2018WK4004)Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001,2020XK2001).
文摘Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer is of vital import-ance for guiding the design of functional optoelectronic applications.In this work,type-Ⅱ0D-2D CdSe/ZnS quantum dots/MoS_(2)vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances.From spectral measurements in both steady and transient states,the phenomena of suppressed photolu-minescence(PL)emissions,shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface.A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details,which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10^(13)cm^(−2).The enhanced photoresponses(1.57×10^(4)A·W^(-1))and detectivities(2.86×10^(11)Jones)in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices.These results are expected to inspire the basic understand-ing of interfacial physics at 0D/2D interfaces,and shed the light on promoting the development of mixed-dimensional op-toelectronic devices in the near future.
基金the National Basic Research Program of China (No. 2012CB932703)the NSF of China (Nos. 11374092 and 11204073)+2 种基金the Research Fund for the Doctoral Program of Higher Education (Nos. 20110161110034, 20110161120027)the Fundamental Research Funds for Central Universities (Nos. xjj2011001 and 2012jdgz04)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (2013)
文摘In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in air. During the measurement, a focused laser was used to heat one end of a freely suspended nanowire, with its other end embedded into a carbon conductive adhesive. In order to obtain the thermal conductivity of In As nanowires, the heat loss in the heat transfer process was estimated, which includes the heat loss through air conduction, the heat convection, and the radiation loss. The absorption ratio of the laser power in the In As nanowire was calculated. The result shows that the thermal conductivity of In As nanowires monotonically increases from 6.4 W m-1K-1to 10.5 W m-1K-1with diameters increasing from 100 nm to 190 nm, which is ascribed to the enhanced phonon-boundary scattering.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52022029,91850116,51772084,62090035,and U19A2090)Hunan Provincial Natural Science Foundation of China(Grant Nos.2018RS3051 and 2018WK4004)the Key Program of the Hunan Provincial Science and Technology Department(Grant No.2019XK2001).
文摘Two-dimensional(2D)magnetic materials have aroused tremendous interest due to the 2D confinement of magnetism and potential applications in spintronic and valleytronic devices.However,most of the currently 2D magnetic materials are achieved by the exfoliation from their bulks,of which the thickness and domain size are difficult to control,limiting the practical device applications.Here,we demonstrate the realization of thickness-tunable rhombohedral Cr_(2)Se_(3)nanosheets on different substrates via the chemical vapor deposition route.The magnetic transition temperature at about 75 K is observed.Furthermore,van der Waals heterostructures consisting of Cr_(2)Se_(3)nanosheets and monolayer WS2 are constructed.We observe the magnetic proximity effect in the heterostructures,which manifests the manipulation of the valley polarization in monolayer WS2.Our work contributes to the vapor growth and applications of 2D magnetic materials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21773303,21872172,51472267,and 51421002)the Chinese Academy of Sciences(Grant Nos.ZDYZ2015-1,XDB30000000,and XDB07030100)
文摘Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium sulfide(CdS) nanowires are investigated by a customer-built optical holder inside transmission electron microscope, wherein in situ electromechanical resonance took place in conjunction with photo excitation. It is found that the natural resonance frequency of the nanowire under illumination becomes considerably lower than that under darkness. This redshift effect is closely related to the wavelength of the applied light and the diameter of the nanowires. Density functional theory(DFT) calculation shows that the photoexcitation leads to the softening of CdS nanowires and thus the redshift of natural frequency, which is in agreement with the experimental results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91850116,51772084,52022029,and U19A2090)Hunan Provincial Natural Science Foundation of China(Grant Nos.2018RS3051 and 2018WK4004)the Key Program of the Hunan Provincial Science and Technology Department,China(Grant No.2019XK2001).
文摘Due to the large exciton binding energy,two-dimensional(2D)transition metal dichalcogenides(TMDCs)provide an ideal platform for studying excitonic states and related photonics and optoelectronics.Polarization states lead to distinct light-matter interactions which are of great importance for device applications.In this work,we study polarized photoluminescence spectra from intralayer exciton and indirect exciton in WS_(2) and WSe_(2) atomic layers,and interlayer exciton in WS_(2)/WSe_(2) heterostructures by radially and azimuthally polarized cylindrical vector laser beams.We demonstrated the same in-plane and out-of-plane polarization behavior from the intralayer and indirect exciton.Moreover,with these two laser modes,we obtained interlayer exciton in WS_(2)/WSe_(2) heterostructures with stronger out-of-plane polarization,due to the formation of vertical electric dipole moment.
基金Project supported by the Science Fund from the Ministry of Science and Technology(MOST)of China(Grant No.2018YFE0202700)the National Natural Science Foundation of China(Grant Nos.11274380,91433103,11622437,61674171,11974422,and 61761166009)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities of China and the Research Funds of Renmin University of China(Grant No.16XNLQ01)the Research Grant No.Council of Hong Kong,China(Grant No.N_PolyU540/17)the Hong Kong Polytechnic University(Grant No.G-SB53).Cong Wang was supported by the Outstanding Innovative Talents Cultivation Funded Programs 2017 of Renmin University of China.
文摘At least four two-or quasi-one-dimensional allotropes and a mixture of them were theoretically predicted or experimentally observed for low-dimensional Te,namely theα,β,γ,δ,and chiral-α+δphases.Among them theγandαphases were found to be the most stable phases for monolayer and thicker layers,respectively.Here,we found two novel low-dimensional phases,namely theεandζphases.Theζphase is over 29 meV/Te more stable than the most stable monolayerγphase,and theεphase shows comparable stability with the most stable monolayerγphase.The energetic difference between theζandαphases reduces with respect to the increased layer thickness and vanishes at the four-layer(12-sublayer)thickness,while this thickness increases under change doping.Bothεandζphases are metallic chains and layers,respectively.Theζphase,with very strong interlayer coupling,shows quantum well states in its layer-dependent bandstructures.These results provide significantly insight into the understanding of polytypism in Te few-layers and may boost tremendous studies on properties of various few-layer phases.
基金supported this research endeavor.Notably,the National Natural Science Foundation of China(No.52373311)the Science Talent Program of China,the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2020JJ2059)+10 种基金the Hunan Province Key Research and Development Project(No.2019GK2233)the Youth Innovation Team(No.2019012)of Central South University(CSU)have played an essential role in facilitating the success of this study.Furthermore,the Science and Technology Innovation Basic Research Project of Shenzhen(No.JCYJ20190806144418859)the Key Program of the Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the National Natural Science Foundation of China(Nos.62090035 and U19A2090)have also made significant contributions to the advancement of this workThe support provided by the High-Performance Complex Manufacturing Key State Lab Project at CSU(No.ZZYJKT2020-12)has been of immeasurable value,greatly expediting the research processAcknowledgment is also extended to the Australian Research Council(ARC Discovery Project,DP180102976)for its pivotal role in driving forward this research agenda.AdditionallyJ.T.W.extends gratitude for the support received from the National Natural Science Foundation of China(Nos.92263202 and 11974387)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB33000000)the National Key Research and Development Program of China(No.2020YFA0711502)The authors also wish to convey their deep appreciation to the Beijing Super Cloud Computing Center(BSCC,http://www.blsc.cn)for granting access to high-performance computing(HPC)resources,which have been instrumental in yielding the research outcomes detailed in this paper.Finally,the authors hold profound gratitude for the support of the Postdoctoral Science Foundation of China(No.2022M713546)a vital contribution that has substantially propelled the advancement of this research endeavor.This work was supported in part by the High-Performance Computing Center of Central South University.
文摘Moirésuperlattices,arising from the controlled twisting of van der Waals homostructures at specific angles,have emerged as a promising platform for quantum emission applications.Concurrently,the manipulation of strain provides a versatile strategy to finely adjust electronic band structures,enhance exciton luminescence efficiency,and establish a robust foundation for two-dimensional quantum light sources.However,the intricate interplay between strain and moirépotential remains partially unexplored.Here,we introduce a meticulously designed fusion of strain engineering and the twisted 2L-WSe_(2)/2L-WSe_(2) homobilayers,resulting in the precise localization of moiréexcitons.Employing low-temperature photoluminescence spectroscopy,we unveil the emergence of highly localized moiré-enhanced emission,characterized by the presence of multiple distinct emission lines.Furthermore,our investigation demonstrates the effective regulation of moirépotential depths through strain engineering,with the potential depths of strained and unstrained regions differing by 91%.By combining both experimental and theoretical approaches,our study elucidates the complex relationship between strain and moirépotential,thereby opening avenues for generating strain-induced moiréexciton single-photon sources.
基金supported by the National Natural Science Foundation of China(62104066,52221001,62090035,U19A2090,U22A20138,52372146,and 62101181)the National Key R&D Program of China(2022YFA1402501,2022YFA1204300)+6 种基金the Natural Science Foundation of Hunan Province(2021JJ20016)the Science and Technology Innovation Program of Hunan Province(2021RC3061)the Key Program of Science and Technology Department of Hunan Province(2019XK2001,2020XK2001)the Open Project Program of Wuhan National Laboratory for Optoelectronics(2020WNLOKF016)the Open Project Program of Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(22ZS01)the Project funded by China Postdoctoral Science Foundation(2023TQ0110)the Innovation Project of Optics Valley Laboratory(OVL2023ZD002).
文摘The growth of data and Internet of Things challenges traditional hardware,which encounters efficiency and power issues owing to separate functional units for sensors,memory,and computation.In this study,we designed an a-phase indium selenide(a-In_(2)Se_(3))transistor,which is a two-dimensional ferroelectric semiconductor as the channel material,to create artificial optic-neural and electro-neural synapses,enabling cutting-edge processing-in-sensor(PIS)and computing-in-memory(CIM)functionalities.As an optic-neural synapse for low-level sensory processing,the a-In_(2)Se_(3)transistor exhibits a high photoresponsivity(2855 A/W)and detectivity(2.91×10^(14)Jones),facilitating efficient feature extraction.For high-level processing tasks as an electro-neural synapse,it offers a fast program/erase speed of 40 ns/50μs and ultralow energy consumption of 0.37 aJ/spike.An AI vision system using a-In_(2)Se_(3)transistors has been demonstrated.It achieved an impressive recognition accuracy of 92.63%within 12 epochs owing to the synergistic combination of the PIS and CIM functionalities.This study demonstrates the potential of the a-In_(2)Se_(3)transistor in future vision hardware,enhancing processing,power efficiency,and AI applications.
基金support from the following funding:the National Key R&D Program of China(No.2022YFA1204300)the National Natural Science Foundation of China(Nos.62104066,52221001,62090035,U19A2090,U22A20138 and 51902098)+5 种基金the Natural Science Foundation of Hunan Province(No.2021JJ20016)the Science and Technology Innovation Program of Hunan Province(Nos.2021RC3061 and 2020RC2028)the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2020WNLOKF016)the National Postdoctoral Program for Innovative Talents(No.BX2021094)the Postdoctoral Science Foundation of China(No.2020M680112).
文摘Transition metal dichalcogenides(TMDCs)are promising candidates for future optoelectronic devices accounting for their high carrier mobility and excellent quantum efficiency.However,the limited light absorption efficiency in atomically thin layers significantly hinders photocarrier generation,thereby impairing the optoelectronic performance and hindering practical applications.Herein,we successfully synthesized In_(2)Se_(3)/WSe_(2) heterostructures through a typical two-step chemical vapor deposition(CVD)method.The In_(2)Se_(3) nanosheet with strong light absorption capability,serving as the light absorption layer,was integrated with the monolayer WSe_(2),enhancing the photosensitivity of WSe_(2) significantly.Upon laser irradiation with a wavelength of 520 nm,the In_(2)Se_(3)/WSe_(2) heterostructure device shows an ultrahigh photoresponsivity with a value as high as 2333.5 A/W and a remarkable detectivity reaching up to 6.7×10^(12) Jones,which is the highest among almost the reported TMDCs-based heterostructures grown via CVD even some fabricated by mechanical exfoliation(ME).Combing the advantages of CVD method such as large scale,high yield,and clean interface,the In_(2)Se_(3)/WSe_(2) heterostructures would provide a novel path for future high-performance optoelectronic device.
基金the National Natural Science Foundation of China(Nos.51772085,12072110)the Natural Science Foundation of Hunan Province(No.2020JJ4190).
文摘Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectation.Herein,we demonstrate a competitive assembling strategy for the construction of metal-free graphite carbon nitride(CN)homojunctions in which morphology and composition can be easily controlled simultaneously by only changing the ratio of assembly raw materials.These homojunctions are comprised of porous nanotubular S-doped CN(SCN)grafted with CN nanovesicles,which are derived from thermal polycondensation of melamine-thiocyanuric acid(M-T)/melamine-cyanuric acid(M-C)supramolecular hybrid blocks.This unique architecture and component engineering endows the novel SCN-CN homojunction with abundant active sites,enhanced visible trapping ability,and intimate interface contact.As a result,the synthesized SCN-CN homojunctions demonstrate high photocatalytic activity for hydrogen evolution and pollutant degradation.This developed strategy opens up intriguing opportu-nities for the rational construction of intricate metal-free heterostructures with controllable architecture and interfacial contact for applications in energy-related fields.
基金supported by the National Natural Science Foundation of China(Nos.62101181,2221001,62090035,52372146,U22A20138,and U19A2090)the National Key Research and Development Program(Nos.2022YFA1204300 and 2022YFA1402501)+4 种基金Natural Science Foundation of Hunan Province(No.2023JJ20016)the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the Key Research and Development Plan of Hunan Province(No.2023GK2012)the Science and Technology Innovation Program of Hunan Province(No.2021RC3061)the Open Project Program of Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(No.22ZS01).
文摘Stretchable electronics have found widespread applications in various fields such as wearable electronics,soft robots,and bioelectronics.As an important promising alternative of traditional rigid conductors,liquid metals have demonstrated immense potential to provide high conductivity and stretchability for the stretchable electronic systems.However,limited by their fluidity and high surface tension,challenges remain in achieving liquid metal patterns with low-cost,high-precision,large-scale,and complex geometry.Here,a fabrication technique was proposed based on laser-induced graphene(LIG)stamps to enable liquid metal self-selectively adhere to substrates.Liquid metal patterns could thus be achieved in different designed geometries and could be transferred onto stretchable substrates.The liquid metal patterns exhibit exceptional electrical conductivity(3.24×10^(6)S/m even under 1000%strain),high stretchability(1000%strain,maximum of 2500%),small resistance changes under significant deformations(with a quality factor of 62.5 under 1000%strain),and high resolution(down to 50μm).Utilizing the patterned liquid metals,a stretchable integrated multifunctional optoelectronic system was demonstrated,encompassing a stretchable display matrix,a pressure sensor array,a wireless powering coil,and cardiovascular sensors,which further highlight the remarkable application potential of liquid metals in optoelectronic user-interaction and advanced physiological monitoring.
基金supported by the National Key R&D Program of China(Nos.2021YFB2802000 and 2022YFA1204300)the Shanghai Municipal Science and Technology Commission Innovation Action Plan(No.18DZ1100400)+4 种基金the National Natural Science Foundation of China(Nos.52221001,62090035,62175061,and U19A2090)the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the Key Research and Development Plan of Hunan Province(No.2023GK2012)the Open Project of Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(No.22ZS01)the Natural Science Foundation of Hunan Province(No.2022JJ30167).
文摘Electron-trapping materials,due to their exceptional ability of energy storage and controllable photon release under external stimulation,have attracted considerable attention in the field of optical information storage(OIS).In this work,Gd_(3)Al_(3)Ga_(2)O_(12):Ce^(3+), Yb^(3+)fluorescent ceramics,were developed using air and vacuum sintering technology.By co-doping Ce^(3+)and Yb^(3+),the trap density was significantly increased by 7.5 times compared to samples containing only Ce^(3+).Vacuum annealing further enhanced trap density by 1.6 times compared to samples sintered solely in air,while generating deep traps(1.44 eV),making Gd_(3)Al_(3)Ga_(2)O_(12):Ce^(3+), Yb^(3+) an excellent OIS medium.This work is expected to facilitate the development of OIS materials.
基金supported by the Ministry of Science and Technology of China(2016YFA0200103)the National Natural Science Foundation of China(51672153,21975141)the National Program for Support of Top-notch Young Professionals.
文摘Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and compactness of hybrid perovskite are key factors affecting the performance of photoelectric devices.The photocurrent and photoresponsivity of these devices are relatively low because of the rapidly recombined photoexcited electron-hole pairs in hybrid perovskite.Herein,we develop a facile two-step chemical vapor deposition(CVD)method to synthesize a high-quality van der Waals(vd Ws)MAPb I3/graphene heterostructure for high-performance image sensor.We introduced inorganic sources(PbI2)to vd Ws epitaxially grown Pb I2 film on a seamless graphene monolayer film template through CVD.Methylammonium iodide(MAI)was then reintroduced to prepare the vd Ws MAPb I3/graphene heterostructure.The MAPb I3 layer is composed of densely packed,large-size grains and displays a smooth surface.High photoresponsivity of 107A/W is achieved in the corresponding photodetector.Inspired by the human visual system,we designed a flexible photodetector array containing(24?24)pixels,achieving perfect image recognition and color discrimination.Our study may greatly facilitate the construction of high-performance optoelectronic devices in artificial retina,biomedical imaging,remote sensing,and optical communication.
基金support by the National Natural Science Foundarion of China(Grant No.52005175,5211101255)Natural gcience Foundation of Hunan Province of China(Grant No.2020J15059)+1 种基金Shenzhen Science and Technology Program(Grant No.RCBS20200714114855118)the Tribology Science Fund of State Key Laboratory of Tribology(SKILTKF20B04)。
文摘Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perform machine learning tasks through linear optical transformations.However,the existing architectures often comprise bulky components and,most critically,they cannot mimic the human brain for multitasking.Here,we demonstrate a multi-skilled diffractive neural network based on a metasurface device,which can perform on-chip multi-channel sensing and multitasking in the visible.The polarization multiplexing scheme of the subwavelength nanostructures is applied to construct a multi-channel classifier framework for simultaneous recognition of digital and fashionable items.The areal density of the artificial neurons can reach up to 6.25×10^(6)mm^(-2) multiplied by the number of channels.The metasurface is integrated with the mature complementary metal-oxide semiconductor imaging sensor,providing a chip-scale architecture to process information directly at physical layers for energy-efficient and ultra-fast image processing in machine vision,autonomous driving,and precision medicine.
基金Acknowledgements All authors are grateful to the National Natural Science Foundation of China （Nos. 51525202, 61574054, 61505051 and 61474040）, the Hunan province science and technology plan （Nos. 2014FJ2001 and 2014TT1004）, the Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, and the Fundamental Research Funds for the Central Universities.
文摘High-performance multiphoton-pumped lasers based on cesium lead halide perovskite nanostructures are promising for nonlinear optics and practical frequency upconversion devices in integrated photonics. However, the performance of such lasers is highly dependent on the quality of the material and cavity, which makes their fabrication challenging. Herein, we demonstrate that cesium lead halide perovskite triangular nanorods fabricated via vapor methods can serve as gain media and effective cavities for multiphoton-pumped lasers. We observed blue-shifts of the lasing modes in the excitation fluence-dependent lasing spectra at increased excitation powers, which fits well with the dynamics of Burstein-Moss shifts caused by the band filling effect. Moreover, efficient multiphoton lasing in CsPbBr3 nanorods can be realized in a wide excitation wavelength range （700-1,400 nm）. The dynamics of multiphoton lasing were investigated by time-resolved photoluminescence spectroscopy, which indicated that an electron-hole plasma is responsible for the multiphoton-pumped lasing. This work could lead to new opportunities and applications for cesium lead halide perovskite nanostructures in frequency upconversion lasing devices and optical interconnect systems.
基金the National Natural Science Foundation of China (Nos.51525202, 51772084, 61574054, 61635001, and 51802089)Innovation platform and talent plan of Hunan Province (No.2017RS3027)+1 种基金the Program for Youth Leading Talent and Science and Technology Innovation of Ministry of Science and Technology of Chinathe Foundation for Innovative Research Groups of NSFC (No.21521063).
文摘Lead halide perovskites have received tremendous attentions recently for their excellent properties such as high light absorption coefficient and long charge carrier diffusion length. However, the stability issues and the existence of toxic lead cations have largely limited their applications in optoelectronic area. Herein, we report the synthesis and investigation of highly stable and lead-free Cs3Bi2I9 perovskite nanoplates for visible light photodetection applications. The Cs3Bi2I9 nanoplates were synthesized through a facile solution-processed method, which is also applicable to various substrates. The achieved nanoplates present very good crystal quality and exhibit excellent long-term stability even exposed in moist air for several months. Photodetectors were constructed based on these high-quality perovskite nanoplates for the first time, and display a maximum photoresponsivity of 33.1 mA/W under the illumination of 450 nm laser, which is six times higher than the solution-synthesized CH3NH3PbI3 nanowire photodetectors. The specific detectivity of these devices can reach up to 10^10 Jones. Additionally, the devices exhibit fast rise and decay time of 10.2 and 37.2 ms, respectively, and highly stable photoswitching behavior with their photoresponse well retaining under alternating light and darkness. This work opens up a new opportunity for stable and low-toxic perovskite-based optoelectronic applications.
