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Optical properties of two-dimensional perovskites

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Frontiers of physics 2023年第3期18卷 1-26页

作者： Junchao Hu Xinglin Wen dehui li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

The optical properties of two-dimensional(2D)perovskites recently receive numerous research focus thanks to the strong quantum and dielectric confinement *** addition to the strong excitonic effect at room temperature,2D perovskites also have appealing features that their optical properties can be flexibly tuned by alternating organic or inorganic ***,2D chiral perovskites and 2D perovskites based heterostructures are emerging as new platforms to extend their *** optimize performance of 2D perovskites-based optoelectronic devices,it is critical to understand the fundamentals and explore the strategies to engineer their optical *** review begins with an introduction to the excitons and self-trapped excitons of 2D ***,inorganic/organic layer effects on optical properties and 2D perovskites based heterostructures are *** also discussed the nonlinear optical properties of 2D *** are looking forward to that this review can stimulate more efforts to understand and optimize the optical properties of 2D perovskites.

关键词： optical properties two-dimensional perovskite heterostructures self-trapped excitons

Epitaxial growth of CsPbBr_(3)-PbS vertical and lateral heterostructures for visible to infrared broadband photodetection

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Nano Research 2021年第11期14卷 3879-3885页

作者： Qingbo liu lihan liang Hongzhi Shen dehui li Hong Zhou School of Physics and Electronics Hunan UniversityChangsha410082China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan430074China

Owing to their excellent optoelectronic properties, halide perovskite is very promising for photodetectors and other optoelectronic devices. Perovskite heterostructures are considered to be the key components for these devices. However, it is challenging to rationally synthesize those heterostructures. Here, we demonstrate that perovskite can be epitaxially grown on PbS by vapor transport, thereby creating an interesting CsPbBr_(3)-PbS heterostructure. Remarkably, photodetectors based on CsPbBr_(3)-PbS heterostructures exhibit visible to infrared broadband response with room temperature operation up to 2 μm. The room temperature detectivity higher than 1.0 × 10^(9) Jones was obtained in the 1.8- to 2-μm range. Furthermore, the p-n heterojunction exhibits a clear rectifying characteristic and enables detector to operate at zero-bias. Our study provides fundamentally contributes to establish the epitaxial growth perovskite heterostructures and demonstrate a materials platform for efficient perovskite-based optoelectronic devices.

关键词： perovskites PbS heterostructure epitaxial growth short-wavelength infrared

Toward modeling of the scrape-off layer currents induced by electrode biasing using 2D particle-in-cell simulations

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Plasma Science and Technology 2020年第10期22卷 62-75页

作者： Huaxiang ZHANG dehui li Yunfeng liANG Institute of Plasma Physics Chinese Academy o f SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Forschungszentrum Jiilich GmbH.Institut fiir Energie und Klimaforschung Plasmaphysik.Trilateral Euregio Cluster D-52425 JiilichGermany

The property of scrape-off layer(SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell(PIC) simulations. A reduced Vlasov–Darwin model is employed, which is capable of describing the low-frequency kinetic behavior without electromagnetic vacuum modes(w^2=w_(pe)~2+ c^2k^2). A linear decay distribution of electron currents parallel to the background magnetic field is exhibited. Simulation analyses indicate that the cross field ion current is a key factor in sheath formation and global current balance. The influences of electrode area, biasing voltage and plasma source on the SOL current profile are studied, *** plasma parameters in the far SOL region of the EAST tokamak are used in simulations to assess the current driving ability of the electrode biasing method. Due to the limitations of computational power, the geometrical size of the simulation domain is significantly smaller than the realistic SOL, which may lead to an absence of the quasi-neutral region in the upstream *** last, a heuristic method is proposed to calculate the upper bound of the total current strength.

关键词： scrape-off layer electrode biasing particle-in-cell

Nonlinear optics of two-dimensional transition metal dichalcogenides

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InfoMat 2019年第3期1卷 317-337页

作者： Xinglin Wen Zibo Gong dehui li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhanChina Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhanChina

Nonlinear optics(NLO)of transition metal dichalcogenides(TMDs)is promising for the on-chip photonic and optoelectronic *** this review,we will survey the current progress of NLO in ***,we will brief the basic theory of the NLO in ***,several important nonlinear processes in TMDs such as harmonic generation,four-wave mixing,saturable absorption,and two-photon absorption will be presented and their potential applications are also ***,the main strategies to tune,modulate,and enhance the NLO in TMDs are reviewed,including the excitonic effect,symmetry modulation,optical cavity enhancement,valley selection,edge state,and material ***,we give an outlook regarding some important issues and directions of NLO in TMDs.

关键词： NLO modulation and enhancement nonlinear devices nonlinear optics transition metal dichalcogenides

Nonvolatile electrical switching of optical and valleytronic properties of interlayer excitons

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light(Science & Applications) 2022年第2期11卷 221-229页

作者： Tong Ye Yongzhuo li Junze li Hongzhi Shen Junwen Ren Cun-Zheng Ning dehui li School of Optical and Electronic Information Huazhong University of Science and Technology430074 WuhanChina Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology430074 WuhanChina Department of Electronic Engineering Tsinghua University100084 BeijingChina Frontier Science Center for Quantum Information 100084 BeijingChina School of Electrical Computerand Energy EngineeringArizona State UniversityTempeAZ 85287USA

Long-lived interlayer excitons(IXs)in van der Waals heterostructures(HSs)stacked by monolayer transition metal dichalcogenides(TMDs)carry valley-polarized information and thus could find promising applications in valleytronic *** manipulation approaches for valley polarization of IXs are mainly limited in electrical field/doping,magnetic field or twist-angle ***,we demonstrate an electrochemical-doping method,which is efficient,in-situ and *** find the emission characteristics of IXs in WS2/WSe2 HSs exhibit a large excitonic/valley-polarized hysteresis upon cyclic-voltage sweeping,which is ascribed to the chemical-doping of O2/H2O redox couple trapped between WSe2 and *** advantage of the large hysteresis,a nonvolatile valley-addressable memory is successfully *** valley-polarized information can be non-volatilely switched by electrical gating with retention time exceeding 60 *** findings open up an avenue for nonvolatile valley-addressable memory and could stimulate more investigations on valleytronic devices.

关键词： nonvolatile valley electrical

Effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and nerve growth factor expression in a rat model of sciatic nerve injury

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Neural Regeneration Research 2009年第12期4卷 1002-1006页

作者： Min Ma Guijuan Zhang Yi Ma dehui li Hening Zhai Department of Traditional Chinese Medicine Medical College of Jinan University Guangzhou 510632 Guangdong Province China First Hospital Affiliated to Jinan University Guangzhou 510632 Guangdong Province China Institute of Bioengineering Jinan University Guangzhou 510632 Guangdong Province China

BACKGROUND： Studies have shown that both salviae miltiorrhizae and ligustrazine can promote protein expression of nerve growth factor （NGF） and regeneration of peripheral nerve. OBJECTIVE： To verify the effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and NGF protein expression in a rat model of sciatic nerve injury. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Laboratory of Traditional Chinese Medicine and the Institute of Bioengineering of Jinan University from July to December 2008. MATERIALS： Salviae miltiorrhizae and ligustrazine hydrochloride injection （containing 20 mg salviae miJtiorrhizae and 100 mg ligustrazine per 100 mL injection） was provided by Guizhou Baite Pharmaceutical, China; salviae miltiorrhizae and ligustrazine decoctions （containing 1 g raw drug per 1 mL decoction） were provided by Guangzhou Baiyunshan Factory for Traditional Chinese Medicine, China; rabbit-anti-rat NGF monoclonal antibody was provided by Beijing Biosynthesis Biotechnology, China. METHODS： A total of 80 healthy, male, Sprague Dawley rats were used to establish a sciatic nerve injury model via neurotomy, and were then randomly assigned to 4 groups： salviae miltiorrhizae and ligustrazine hydrochloride injection group （intraperitoneal injection of 35 mL/kg per day salviae miltiorrhizae and ligustrazine hydrochloride injection）, saIviae miltiorrhizae group （intragastric peffusion of 2 mL salviae miltiorrhizae）, ligustrazine group （intragastric peffusion of 2 mL ligustrazine）, and model group （intraperitoneal injection of 35 mL/kg per day saline）, with 20 rats in each group. Thereafter, rats in each group were then divided into 4 subgroups according to varying time points of 1, 2, 4, and 8 weeks post-surgery, with 5 rats in each subgroup. MAIN OUTCOME MEASURES： Axons were quantified using chromotrope 2R-brilliant green and silver staining combined with image analysis to calculate the axonal

关键词： nerve growth factor sciatic nerve salviae miltiorrhizae and ligustrazine hydrochloride injection axonal regeneration

Research on Initial Alignment for Large Azimuth Misalignment Angle with SageHusa Adaptive Filtering

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Research on Initial Alignment for Large Azimuth Misalignment...

Surface depletion field in 2D perovskite microplates: Structural phase transition, quantum confinement and Stark effect

第25届中国控制与决策会议

作者： Cheng Zijian He Xiaofei Jiang Huan li dehui Beijing Aerospace Times Optical-electronic Technology Co. Ltd

ISBN: (纸本)9781467355339

The azimuth was often a large angle because navigation accuracy of fiber-optic inertial navigation system is not high, and the filtering equations of initial alignment are non-linear. In order to improve the initial alignment accuracy of nonlinear models, a improved Sageusa adaptive Kalman filtering method is put forward , and applied to initial alignment of fiber-optic inertial navigation system. This paper establishes initial alignment nonlinear model of large azimuth misalignment angle, contributes the system noise statistics estimators, and uses improved Sageusa adaptive Kalman filtering to simulate for nonlinear error equations. The simulation results show that the improved Sageusa adaptive Kalman filtering could deal with nonlinear problems, improve the accuracy of initial alignment. Azimuth misalignment angle error can converge 13.353’ better than 48.539’ of EKF.

关键词： fiber-optic initial navigation system initial alignment SageHusa adaptive kalman filter nonlinear

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Nano Research 2019年第11期12卷 2858-2865页

作者： Wancai li Chen Fang Haizhen Wang Shuai Wang Junze li Jiaqi Ma Jun Wang Hongmei Luo dehui li School of Optical and Electronic Information and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan430074China Department of Chemical and Materials Engineering New Mexico State UniversityLas CrucesNM88003USA

Surface depletion field would introduce the depletion region near surface and thus could significantly alter the optical,electronic and optoelectronic properties of the materials,especially low-dimensional ***-dimensional(2D)organic—inorganic hybrid perovskites with van der Waals bonds in the out-of-plane direction are expected to have less influence from the surface depletion field;nevertheless,studies on this remain *** we report on how the surface depletion field affects the structural phase transition,quantum confinement and Stark effect in 2D(BA)2PbI4 perovskite microplates by the thickness-,temperature-and power-dependent photoluminescence(PL)*** dependent PL studies suggest that high-temperature phase(HTP)and low-temperature phase(LTP)can coexist in a wider temperature range depending on the thickness of the 2D perovskite *** the decrease of the microplate thickness,the structural phase transition temperature first gradually decreases and then increases below 25 nm,in striking contrast to the conventional size dependent structural phase *** on the thickness evolution of the emission peaks for both high-temperature phase and low-temperature phase,the anomalous size dependent phase transition could probably be ascribed to the surface depletion field and the surface energy difference between *** explanation was further supported by the temperature dependent PL studies of the suspended microplates and encapsulated microplates with graphene and boron nitride *** with the thickness dependent phase transition,the emission energies of free excitons for both HTP and LTP with thickness can be ascribed to the surface depletion induced confinement and Stark effect.

关键词： two-dimensional(2D)perovskite thickness surface depletion field structural phase transition quantum confinement Stark effect

A stabilizing model predictive control for networked control system with data packet dropout

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控制理论与应用（英文版） 2009年第3期7卷 281-284页

作者： Zhijun li dehui SUN Yuntao SHI lifeng WANG Department of Automation North China University of Technology Beijing 100044 China

A constrained model predictive control （MPC） algorithm for networked control system with data packet dropout is proposed in this paper. A buffer is designed to store the predicted control sequence between controller and actuator. It is shown that if the control horizon of MPC is not less than the number of data packets lost continuously, feasibility of MPC at initial time implies asymptotical stability of the closed-loop system. A simulation example illustrates the effectiveness of the proposed approach.

关键词： Networked control system Model predictive control Stability