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nano Research 2024年第3期17卷 1856-1863页

作者： Cheng Zhang Biyuan Zheng Guangcheng Wu Xueying Liu Jiaxin Wu Chengdong Yao Yizhe Wang Zilan Tang Ying Chen Lizhen Fang Luying Huang Dong Li Shengman Li Anlian Pan key laboratory for micro-nano physics and technology of hunan province State Key Laboratory of Chemo/Biosensing and ChemometricsCollege of Materials Science and EngineeringHunan UniversityChangsha 410082China

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.

关键词： transition metal dichalcogenides(TMDCs) In_(2)Se_(3) heterostructure photodetector ultrahigh responsivity

Ultrafast optical investigation of carrier and spin dynamics in low-dimensional perovskites

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Science China(Technological Sciences) 2024年第1期67卷 2-18页

作者： FU JinYue JIANG Ying FANG HongHua key laboratory for micro-nano physics and technology of hunan province School of Physics and ElectronicsHunan UniversityChangsha 410012China State key laboratory of Precision Measurement technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Low-dimensional perovskite(PVK)materials have attracted significant research interest,because of their quantum-confined effect,tunable band gap structures,and higher stability than that of three-dimensional(3D)PVKs.In semiconductor optoelectronic devices,high speed and small size are closely interlinked.The development of high-speed devices requires researchers to fully understand the properties of materials,especially the dynamic processes such as carrier recombination,separation,and transport,which often play a crucial role in the performance of devices.As an indispensable part of dynamic research,spin relaxation is also of great significance in studying the properties of materials and explore possible applications.Lead halide PVK materials have strong spin-orbit coupling(SOC),which provides a basis for information storage and processing by using spin degrees of freedom.Therefore,studying the carrier and spin dynamics of low-dimensional PVKs is an effective way to understand the internal properties of low-dimensional PVKs clearly.This paper summarizes the latest research progress on the ultrafast carrier and spin dynamics in low-dimensional PVKs,to comprehensively understand their carrier and spin behaviors and present an outlook for relevant studies in this area.

关键词： low-dimensional perovskites carrier dynamics spin dynamics optoelectronic devices

Sulfur vacancies and heterogeneous interfaces promote high performance sodium storage of bimetallic chalcogenide hollow nanospheres

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Journal of Energy Chemistry 2024年第8期95卷 596-610页

作者： Shiyue Cao Xiaoting Xu Qiming Liu Huijuan Zhu Ting Hu key laboratory of Artificial micro-and nano-structures of Ministry of Education School of Physics and Technology Wuhan University

Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion batteries.However,due to low inherent conductivity and significant volume expansion,the electrochemical performance is greatly limited.In this study,a nickel/manganese sulfide material(Ni0.96Sx/MnSy-NC) with adjustable sulfur vacancies and heterogeneous hollow spheres was prepared using a simple method.The introduction of a concentration-adjustable sulfur vacancy enables the generation of a heterogeneous interface between bimetallic sulfide and sulfur vacancies.This interface collectively creates an internal electric field,improving the mobility of electrons and ions,increasing the number of electrochemically active sites,and further optimizing the performance of Na+storage.The direction of electron flow is confirmed by Density functional theory（DFT） calculations.The hollow nano-spherical material provides a buffer for expansion,facilitating rapid transfer kinetics.Our innovative discovery involves the interaction between the ether-based electrolyte and copper foil,leading to the formation of Cu9S5,which grafts the active material and copper current collector,reinforcing mechanical supporting.This results in a new heterostructure of Cu9S5with Ni0.96Sx/MnSy,contributing to the stabilization of structural integrity for long-cycle performance.Therefore,Ni0.96Sx/MnSy-NC exhibits excellent electrochemical properties following our modification route.Regarding stability performance,Ni0.96Sx/MnSy-NC demonstrates an average decay rate of 0.00944% after 10,000 cycles at an extremely high current density of 10000 mA g-1,A full cell with a high capacity of 304.2 mA h g-1was also successfully assembled by using Na3V2（PO4）3/C as the cathode.This study explores a novel strategy for interface/vacancy co-modification in the fabrication of high-performance sodium-ion batteries electrode.

关键词： Heterogeneous interface Interactions Sodium ion batteries Sulfur vacancies

Layer-by-layer epitaxy growth of thickness-controllable two-dimensional tungsten disulfide

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Science China(Information Sciences) 2024年第5期67卷 302-310页

作者： Jieyuan LIANG Zixing ZOU Junwu LIANG Di WANG Biao WANG Anshi CHU Jiali YI Cheng ZHANG Lizhen FANG Tian ZHANG Huawei LIU Xiaoli ZHU Dong LI Anlian PAN key laboratory for micro-nano physics and technology of hunan province State Key Laboratory of Chemo/Biosensing and Chemometrics Hunan Institute of Optoelectronic IntegrationCollege of Materials Science and Engineering School of Physics and ElectronicsHunan University School of Electronic Information and Electrical Engineering Changsha University School of physics and Telecommunication Engineering Yulin Normal University Units Semiconductor technology Co. Ltd. School of physics and Electronics Hunan Normal University

Bilayer transition metal dichalcogenides（TMDs） balance the high mobility of single layers with the high state density of multilayers and therefore have promising application prospects in high-performance electronics. However, the layer-controlled growth of 2D materials is still confronted with challenges such as poor repeatability between different labs and a limited understanding of the growth mechanism at the atomic scale. Herein, we report a new carbon-assisted chemical vapor deposition process that can realize the growth of WS2sheets with high yield, precise thickness controllability, and repeatability. We show that carbon can act as a reducing agent and catalyst that preferentially reacts with the WO3precursor to form intermediate WO3-xproducts with low-valence state W. The resulting oxycarbide gas has a low surface adsorption energy when deposited on the surface of as-grown WS2, which provides nucleation sites for the subsequent layer of WS2growth and leads to the vertical growth of WS2sheets. The growth mechanism is thoroughly investigated. Electrical transport measurements show that the produced bilayer WS2possesses a high carrier mobility(up to 58 cm2·V-1·s-1) and small subthreshold swing（estimated to be 148 mV/decade）,which are among the best reported results for TMDs produced using CVD.

关键词： WS$_2$ thickness-controlled growth chemical vapor deposition additive carbon

Phonon transport properties of Janus Pb_(2)XAs(X=P,Sb,and Bi)monolayers:A DFT study

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Chinese physics B 2024年第4期33卷 71-76页

作者：耿嘉鑫张培汤准韵欧阳滔 School of physics and Optoelectronics and hunan key laboratory for micro-nano Energy Materials and Device Xiangtan UniversityXiangtan 411105China hunan Provincial key laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China

Grasping the underlying mechanisms behind the low lattice thermal conductivity of materials is essential for the efficient design and development of high-performance thermoelectric materials and thermal barrier coating materials.In this paper,we present a first-principles calculations of the phonon transport properties of Janus Pb_(2)PAs and Pb_(2)SbAs monolayers.Both materials possess low lattice thermal conductivity,at least two orders of magnitude lower than graphene and h-BN.The room temperature thermal conductivity of Pb_(2)SbAs(0.91 W/m K)is only a quarter of that of Pb_(2)PAs(3.88 W/m K).We analyze in depth the bonding,lattice dynamics,and phonon mode level information of these materials.Ultimately,it is determined that the synergistic effect of low group velocity due to weak bonding and strong phonon anharmonicity is the fundamental cause of the intrinsic low thermal conductivity in these Janus structures.Relative regular residual analysis further indicates that the four-phonon processes are limited in Pb_(2)PAs and Pb_(2)SbAs,and the three-phonon scattering is sufficient to describe their anharmonicity.In this study,the thermal transport properties of Janus Pb_(2)PAs and Pb_(2)SbAs monolayers are illuminated based on fundamental physical mechanisms,and the low lattice thermal conductivity endows them with the potential applications in the field of thermal barriers and thermoelectrics.

关键词： lattice thermal conductivity weak bonding phonon anharmonicity first principles calculations

microscopic growth mechanism and edge states of monolayer 1T'-MoTe2

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Chinese physics B 2024年第4期33卷 474-480页

作者：赵海鹏刘隐杨胜国林陈昉陈明星 Kai Braun 罗心仪李思宇潘安练王笑 key laboratory for micro-nano physics and technology of hunan province School of Physics and ElectronicsCollege of Materials Science and Engineering Hunan University key laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Centre for Quantum Effects and Applications (SICQEA) Hunan Normal University State key laboratory of Powder Metallurgy Central South University Institute of Physical and Theoretical Chemistry and LISA+ University of Tübingen

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'-MoTe2on Au（111）and graphitized silicon carbide（Gr/SiC） by molecular beam epitaxy（MBE）.We investigate the morphology of the grown1T'-MoTe2at 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'-MoTe2,while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe2.We confirm that the size of single crystal 1T'-MoTe2grown 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'-MoTe2nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.

关键词： 1T′-MoTe2 microscopic growth mechanism scanning tunneling microscopy/spectroscopy (STM/S) transition metal ditellurides

Efficient terahertz generation from van der Waalsα-In_(2)Se_(3)

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Chinese Optics Letters 2024年第1期22卷 141-146页

作者：段诗婕杨鸣周溯媛张隆辉韩锦森孙旭王广刘昌勤康冬冬王小伟陈家浩戴佳钰 Department of physics College of ScienceNational University of Defense TechnologyChangsha 410073China hunan key laboratory of Extreme Matter and Applications(XMAL) Changsha 410073China hunan key laboratory for micro-nano Energy Materials and Devices School of Physics and OptoelectronicsXiangtan UniversityXiangtan 411105China Guangxi key laboratory of Automatic Detecting technology and Instrument Guilin University of Electronic TechnologyGuilin 541004China

Two-dimensional(2D)van der Waals materials have attracted tremendous attention due to their versatile physical properties and flexible manipulation approaches.Among the various types of van der Waals materials,α-In_(2)Se_(3)is remarkable for its intrinsic 2D ferroelectricity and high-performance opto-electronic properties.However,the study of theα-In_(2)Se_(3)system in terahertz(THz)radiation is scarce,although it is promising for electrically controlled THz field manipulation.We investigate theα-In_(2)Se_(3)in different thicknesses and report that the THz generation efficiency induced by femtosecond laser pulses can be largely improved by reducing the thickness from the bulk.Furthermore,we reveal the surge current in thin film coupled with THz emission exhibits a different Auger recombination mode,which is helpful in understanding the mechanism and provides insights into the design of 2D highly efficient THz devices.

关键词： van der Waals terahertz carrier dynamics

Competitive assembling strategy to construct carbon nitride homojunctions for boosting photocatalytic performance

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Journal of Materials Science & technology 2024年第5期172卷 23-32页

作者： Hua-Wei Zhang Yuan-Yuan Li Bo Li Jing-Hui Shi Tao Huang Gui-Fang Huang Anlian Pan Wangyu Hu Wei-Qing Huang School of physics&Electronic Engineering Zhengzhou University of Light IndustryZhengzhou 450002China key laboratory for micro/nano Optoelectronic Devices of Ministry of Education&hunan Provincial key laboratory of Low-Dimensional Structural physics and Devices School of Physics and ElectronicsHunan UniversityChangsha 410082China College of Materials Science and Engineering Hunan UniversityChangsha 410082China

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.

关键词： Competitive assembling strategy Supramolecular hybrid blocks Homojunctions Graphite carbon nitride Photocatalytic

Electron-transporting boron-doped polycyclic aromatic hydrocarbons:Facile synthesis and heteroatom doping positions-modulated optoelectronic properties

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Chinese Chemical Letters 2024年第4期35卷 447-451页

作者： Tingting Huang Zhuanlong Ding Hao Liu Ping-An Chen Longfeng Zhao Yuanyuan Hu Yifan Yao Kun Yang Zebing Zeng key laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China Shenzhen Research Institute of hunan University Shenzhen 518000China key laboratory for micro/nano Optoelectronic Devices of Ministry of Education and hunan Provincial key laboratory of Low-Dimensional Structural physics and Devices School of physics and Electronics Hunan UniversityChangsha 410082China

While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.

关键词： Polycyclic aromatic hydrocarbon Optoelectronic properties Heteroatom doping n-Type organic semiconductors Structure–property relationship

Observation of accurately designed bound states in the continuum in momentum space

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Photonics Research 2024年第4期12卷 638-647页

作者： JIAJU WU JINGGUANG CHEN XIN QI ZHIWEI GUO JIAJUN WANG FENG WU YONG SUN YUNHUI LI HAITAO JIANG LEI SHI JIAN ZI HONG CHEN MOE key laboratory of Advanced micro-Structured Materials School of Physics Science and EngineeringTongji UniversityShanghai 200092China State key laboratory of Surface physics Key Laboratory of Micro-and Nano-Photonic Structures(Ministry of Education)and Department of PhysicsFudan UniversityShanghai 200433China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China

Bound states in the continuum(BICs)in artificial photonic structures have received considerable attention since they offer unique methods for the extreme field localization and enhancement of light-matter interactions.Usually,the symmetry-protected BICs are located at high symmetric points,while the positions of accidental BICs achieved by tuning the parameters will appear at some points in momentum space.Up to now,to accurately design the position of the accidental BIC in momentum space is still a challenge.Here,we theoretically and experimentally demonstrate an accurately designed accidental BIC in a two-coupled-oscillator system consisting of bilayer gratings,where the optical response of each grating can be described by a single resonator model.By changing the interlayer distance between the gratings to tune the propagation phase shift related to wave vectors,the position of the accidental BIC can be arbitrarily controlled in momentum space.Moreover,we present a general method and rigorous numerical analyses for extracting the polarization vector fields to observe the topological properties of BICs from the polarization-resolved transmission spectra.Finally,an application of the highly efficient second harmonic generation assisted by quasi-BIC is demonstrated.Our work provides a straightforward strategy for manipulating BICs and studying their topological properties in momentum space.

关键词： polarization tuning resonator