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low-dimensional optoelectronic synaptic devices for neuromorphic vision sensors

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Materials Futures 2023年第3期2卷 72-89页

作者： Chengzhai Lv Fanqing Zhang Chunyang Li Zhongyi Li Jing Zhao School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081People’s Republic of China Beijing Advanced Innovation Center for Intelligent Robots and Systems Beijing Institute of TechnologyBeijing 100081People’s Republic of China

Neuromorphic systems represent a promising avenue for the development of the next generation of artificial intelligence hardware.Machine vision,one of the cores in artificial intelligence,requires system-level support with low power consumption,low latency,and parallel computing.Neuromorphic vision sensors provide an efficient solution for machine vision by simulating the structure and function of the biological retina.Optoelectronic synapses,which use light as the main means to achieve the dual functions of photosensitivity and synapse,are the basic units of the neuromorphic vision sensor.Therefore,it is necessary to develop various optoelectronic synaptic devices to expand the application scenarios of neuromorphic vision systems.This review compares the structure and function for both biological and artificial retina systems,and introduces various optoelectronic synaptic devices based on low-dimensional materials and working mechanisms.In addition,advanced applications of optoelectronic synapses as neuromorphic vision sensors are comprehensively summarized.Finally,the challenges and prospects in this field are briefly discussed.

关键词： optoelectronic synaptic neuromorphic vision sensors synaptic plasticity low-dimensional visual function

Origin of Luminescent Centers and Edge States in low-dimensional Lead Halide Perovskites:Controversies,Challenges and Instructive Approaches

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Nano-Micro Letters 2019年第2期11卷 109-126页

作者： Jiming Bao Viktor G.Hadjiev Department of Electrical and Computer Engineering University of HoustonHoustonTX 77204USA Department of Chemistry University of HoustonHoustonTX 77204USA Materials Science and Engineering University of HoustonHoustonTX 77204USA Texas Center for Superconductivity University of HoustonHoustonTX 77204USA Department of Mechanical Engineering University of HoustonHoustonTX 77204USA

With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made them appealing materials for high-efficiency,low-cost,solar cells and light-emitting devices.As such,recent observations of apparently deep-level and highly luminescent states in low-dimensional perovskites have attracted enormous attention as well as intensive debates.The observed green emission in 2D CsPb2Br5 and 0 D Cs4PbBr6 poses an enigma over whether it is originated from intrinsic point defects or simply from highly luminescent CsPbBr3 nanocrystals embedded in the otherwise transparent wide band gap semiconductors.The nature of deep-level edge emission in 2D Ruddlesden–Popper perovskites is also not well understood.In this mini review,the experimental evidences that support the opposing interpretations are analyzed,and challenges and root causes forthe controversy are discussed.Shortcomings in the current density functional theory approaches to modeling of properties and intrinsic point defects in lead halide perovskites are also noted.Selected experimental approaches are suggested to better correlate property with structure of a material and help resolve the controversies.Understanding and identification of the origin of luminescent centers will help design and engineer perovskites for wide device applications.

关键词： low-dimensional perovskites Luminescent centers Edge states Cesium lead halides Deep-level states Ruddlesden–Popper perovskites

Emerging low-dimensional materials for mid-infrared detection

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Nano Research 2021年第6期14卷 1863-1877页

作者： Jiangbin Wu Nan Wang Xiaodong Yan Han Wang Ming Hsieh Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCA90089USA Mork Family Department of Chemical Engineering and Material Science University of Southern CaliforniaLos AngelesCA90089USA

Mid-infrared(IR)detectors based on the emerging low-dimensional(two-dimensional and quasi one-dimensional)materials offer unique characteristics including large bandgap tunability,optical polarization sensitivity and integrability with typical silicon process,which are not available in the mid-IR detectors based on traditional compound semiconductors.Here,we review the recent progress in study of mid-IR detectors based on the low-dimensional materials,including black phosphorus,black arsenic phosphorus,tellurene and BaTiS3,from the perspectives of crystal structure,material synthesis,optical properties,and the detector characteristics.The detector gain and detectivity are benchmarked,and the unique properties,such as the polarization sensitivity,are discussed.We also provide our perspective about key future research directions in this field.

关键词： mid-infrared detector anisotropy low-dimensional gain detectivity

low-dimensional perovskite materials and their optoelectronics

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InfoMat 2021年第10期3卷 1039-1069页

作者： Tao Zhu Xiong Gong School of Polymer Science and Polymer Engineering College of Engineering and Polymer ScienceThe University of AkronAkronOhioUSA

Three-dimensional(3D)organic-inorganic metal halide perovskite materials possess great potential applications for approaching efficient optoelectronics due to the unique optoelectronic properties of perovskite materials and costeffective manufacturing possibilities of optoelectronics.However,the scientific and technical challenges of 3D perovskite materials were their inferior long-term stability,which hampered their practical applications.The lowdimensional perovskite materials composed of alternating organic and inorganic layers are one of the most credible paths toward stable perovskite photovoltaics and optoelectronics.In this short review,we first present a discussion of the crystal structure and nontrivial optoelectronic properties of the low-dimensional halide perovskites.The synthetic methods for the preparation of the low-dimensional halide perovskites are reviewed.After that,we focus on the recent development of perovskite photovoltaics,light-emitting diodes,and lasers by the low-dimensional halide perovskites.Finally,we outline the challenges of the low-dimensional halide perovskites and their applications.

关键词： lasers light emitting diodes low-dimensional perovskite photodetectors solar cells

POD Analysis and low-dimensional Model Based on POD-Galerkin for Two-dimensional Rayleigh-Bénard Convection

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Journal of Harbin Institute of Technology(New Series) 2018年第1期25卷 67-78页

作者： Hanghang Ma Xin Zheng Yue Wang Jianping Chen Hongna Zhang Weihua Cai School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150001 China Universite de Lyon CNRS INSA-Lyon Universite Claude Bernard Lyon 1 CETHIL UMR5008 F-69621 Villeurbanne France

Direct numerical simulation based on OpenFOAM is carried out for two-dimensional RayleighBénard( RB) convection in a square domain at high Rayleigh number of 107 and Pr = 0.71. Proper orthogonal decomposition( POD) is used to analyze the flow and temperature characteristics from POD energy spectrum and eigenmodes. The results show that the energy spectrum converges fast and the scale of vortex structures captured by eigenmodes becomes smaller as the eigenmode order increases. Meanwhile,a low-dimensional model( LDM) for RB convection is derived based on POD eigenmodes used as a basis of Galerkin project of Navier-Stokes-Boussinesq equations. LDM is built based on different number of eigenmodes and through the analysis of phase portraits,streamline and isothermal predicted by LDM,it is suggested that the error between LDM and DNS is still large.

关键词： Rayleigh-Benard convection proper orthogonal decomposition ( POD) low-dimensional model POD-Galerkin direct numerical simulation ( DNS)

A low-dimensional crystal growth model on an isotropic and quasi-free sustained substrate

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Chinese Physics B 2020年第3期29卷 420-426页

作者：卢晨曦余森江李领伟杨波陶向明叶高翔 College of Materials and Environmental Engineering Hangzhou Dianzi UniversityHangzhou 310018China Department of Physics Zhejiang UniversityHangzhou 310027China

A new crystal growth theoretical model is established for the low-dimensional nanocrystals on an isotropic and quasifree sustained substrate. The driven mechanism of the model is based on the competitive growth among the preferential growth directions of the crystals possessing anisotropic crystal structures, such as the hexagonal close-packed and wurtzite structures. The calculation results are in good agreement with the experimental findings in the growth process of the lowdimensional Zn nanocrystals on silicone oil surfaces. Our model shows a growth mechanism of various low-dimensional crystals on/in the isotropic substrates.

关键词： crystal growth low-dimensional nanocrystals isotropic substrates preferential growth

Recent developments of infrared photodetectors with lowdimensional inorganic nanostructures

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Nano Research 2022年第2期15卷 805-817页

作者： Xin Hu Jianghong Wu Mingzhou Wu Junqing Hu College of Health Science and Environmental Engineering Shenzhen Technology UniversityShenzhen 518118China

low-dimensional inorganic nanostructures such as quantum dots as well as one-and two-dimensional nanostructures are widely studied and already used in high-performance infrared photodetectors.These structures feature large surface-to-volume ratios,tunable light absorption,and electron-limiting effects.This article reviews the state-of-the-art research of low-dimensional inorganic nanostructures and their application for infrared photodetection.Thanks to nano-structuring,a narrow bandgap,hybrid systems,surface-plasmon resonance,and doping,many common semiconductors have the potential to be used for infrared detection.The basic approaches towards infrared detection are summarized.Furthermore,a selection of very important and special nanostructured materials and their remarkable infrared-detection properties are introduced(e.g.,black phosphorus,graphene-based,MoX_(2)-based,Ⅲ-Ⅶ group).Each section in this review describes the corresponding photosensitive properties in detail.The article concludes with an outlook of anticipated future developments in the field.

关键词： infrared photodetectors low-dimensional inorganic nanostructures hybrid structures

Transport signatures of the topological surface state induced by the size effect in superconductor β-PdBi_(2)

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Science China(Physics,Mechanics & Astronomy) 2023年第7期66卷 94-101页

作者： Ankang Zhu Zheng Chen Yuyan Han Mengcheng Zhu Huanhuan Wang Minglong Han Liang Li Xue Liu Guolin Zheng Xiangde Zhu Wenshuai Gao Mingliang Tian Information Materials and Intelligent Sensing Laboratory of Anhui Province Institutes of Physical Science and Information TechnologyAnhui UniversityHefei 230601China Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Key Laboratory of Materials Physics Institute of Solid State PhysicsChinese Academy of SciencesHefei 230601China School of Physics and Optoelectronics Engineering Anhui UniversityHefei 230031China

The superconductivity and nontrivial topological electronic state are key hallmarks of topological superconductors.Here,we focus on the transport signals of possible topological surface state in the topological superconductor candidate β-PdBi_(2) nanoflake with a thickness of 21 nm.The resistance demonstrates a semiconductor-metal transition followed by an upturned behavior as the temperature decreases.A large and unsaturated longitudinal magnetoresistance(MR),accompanied by distinct Shubnikov-de Hass oscillation in Hall resistance,is observed.An analysis of Hall resistance reveals that the carriers present the characteristics of relativistic particles with small effective mass and extremely high mobility.The angle-dependent quantum oscillations demonstrate a two-dimensional Fermi surface topology.A giant anisotropic MR as large as 98%is detected when rotating the magnetic field.These results provide the possible transport signals of a nontrivial topological electronic state,establishing a further understanding of the topological properties of the low-dimensional topological superconductor candidate β-PdBi_(2).

关键词： magnetotransport surface state low-dimensional

A General Synthetic Approach of Organic Lateral Heterostructures for Optical Signal Converters in All-Color Wavelength

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CCS Chemistry 2023年第2期5卷 423-433页

作者： Qiang Lv Xue-Dong Wang Wan-Ying Yang Kai-Li Wang Chao-Fei Xu Min Zheng Liang-Sheng Liao National Engineering Laboratory for Modern Silk College of Textile and Clothing EngineeringResearch Center of Cooperative Innovation for Functional Organic/Polymer Material Micro/NanofabricationSoochow UniversitySuzhouJiangsu 215123 Institute of Functional Nano&Soft Materials(FUNSOM) Soochow UniversitySuzhouJiangsu 215123 Jiangsu General Science&Technology Co. Ltd.Suzhou Industrial ParkSuzhouJiangsu 215123 Macao Institute of Materials Science and Engineering Macao University of Science and TechnologyTaipa 999078Macao SAR

Organic heterostructures with precisely defined compositions,architectures,and interfaces are considered promising building blocks for integrated optoelectronic devices.However,it remains a great challenge to rationally design and synthesize a heterostructure with tunable performance for promising applications such as optoelectronic devices.Herein,we report a universal strategy for the synthesis of organic lateral heterostructures(OLHs)with tunable function and optical properties.We fabricated cocrystals based on the tunable intermolecular distance(dπ–πfrom 3.33 to 3.48Å)ofBenzo[ghi]perylene(BGP)-based driven by arene-perfluoroarene interaction or charge transfer interaction;these different components were selectively constructed into organic solid solution microwires or OLHs.Importantly,the solid solution microwires obtained could be epitaxially grown on the BGP-tetrabromophthalicanhydride trunk microwire to construct a series of OLHs microwires,which led to the successful demonstration of both photonic signal conversion and optical logic gate in all-color wavelength.This work gives a new insight into the fine synthesis of heterostructures with tunable structures/performances,providing predictable synthetic pathways to multifunctional organic heterostructures for the future realization of integrated optoelectronics.

关键词： organic heterostructure low-dimensional structure crystal epitaxial growth integrated photonics