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Regulation of electronic structure of monolayer MoS_(2) by pressure

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Rare Metals 2022年第5期41卷 1761-1770页

作者： Qiao-Lu Lin Zheng-Fang Qian Xiang-Yu Dai Yi-Ling Sun Ren-Heng Wang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Understanding pressure-regulated electronic properties is crucial for integrating two-dimensional semiconductors into flexible electronic devices and pressure sensors. We thoroughly explored the tunability of the electronic structure of monolayer MoS_(2) upon the application of perpendicular pressure and shear stress by using first-principles calculations. The band gap increased at low pressures and then decreased as the pressure increased.Variations in the band gap are caused by the combined interaction of the increasing and decreasing trends in the band gap. The increase in the band gap is induced by the enhancement of the p–d orbital interaction at the top of the valence band(TVB). The delocalization of charge and unstable hybridization bonding causes a reduction in the band gap. The band gap under perpendicular pressure modes is closely related to the structural variation. Shear stress can effectively reduce the band gap with minimal change to the crystal structure. The maximum point at the TVB and the minimum point at the bottom of the conduction band are different for all pressure modes, resulting in various anisotropic properties. This study provides a theoretical basis for modulating the electrical and optical properties of monolayer MoS_(2).

关键词： Band gap Pressure Monolayer MoS_(2) Electronic structure Shear stress

In vivo label-free measurement of blood flow velocity symmetry based on dual line scanning third-harmonic generation microscopy excited at the 1700 nm window

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Journal of Innovative Optical Health Sciences 2024年第1期17卷 61-68页

作者： Hui Cheng Jincheng Zhong Ping Qiu Ke Wang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and optoelectronic Engineering Shenzhen University Shenzhen 518060 P.R.China

Measurement of bloodflow velocity is key to understanding physiology and pathology in vivo.While most measurements are performed at the middle of the blood vessel,little research has been done on characterizing the instantaneous bloodflow velocity distribution.This is mainly due to the lack of measurement technology with high spatial and temporal resolution.Here,we tackle this problem with our recently developed dual-wavelength line-scan third-harmonic generation(THG)imaging technology.Simultaneous acquisition of dual-wavelength THG line-scanning signals enables measurement of bloodflow velocities at two radially symmetric positions in both venules and arterioles in mouse brain in vivo.Our results clearly show that the instantaneous bloodflow velocity is not symmetric under general conditions.

关键词： 1700 nm-Window third-harmonic generation imaging blood flow velocity

Deep-skin third-harmonic generation(THG)imaging in vivo excited at the 2200 nm window

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创新光学健康科学杂志(英文) 2023年第4期16卷 58-65页

作者： Xinlin Chen Yi Pan Ping Qiu Ke Wang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and optoelectronic Engineering Shenzhen University Shenzhen 518060P.R.China

The skin is heterogeneous and exerts strong scattering and aberration onto excitation light in multiphoton microscopy(MPM).Shifting to longer excitation wavelengths may help reduce skin scattering and aberration,potentially enabling larger imaging depths.However,previous demonstrations of skin MPM employ excitation wavelengths only up to the 1700 nm window,leaving an open question as to whether longer excitation wavelengths are suitable for deep-skin MPM.Here,in order to explore the longer-wavelength territory,first,we demonstrate characterization of the broadband transmittance of excised mouse skin,revealing a high transmittance window at 2200nm.Then,we demonstrate third-harmonic generation(THG)imaging in mouse skin in vivo excited at this window.With 9mW optical power on the skin surface operating at 1MHz repetition rate,we can get THG signals of 250m below the skin surface.Comparative THG imaging excited at the 1700nm window shows that as imaging depth increases,THG signals decay even faster than those excited at 2200 nm.Our results thus uncover the 2200 nm window as a new,promising excitation window potential for deep-skin MPM.

关键词： Third-harmonic generation 2200 nm 1700 nm skin

Super-resolution imaging of the dynamic cleavage of intercellular tunneling nanotubes

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Frontiers of optoelectronics 2020年第4期13卷 318-326页

作者： Wanjun GONG Wenhui PAN Ying HE Meina HUANG Jianguo ZHANG Zhenyu GU Dan ZHANG Zhigang YANG Junie QU Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

As a new method of cell-cell communication,tunneling nanotubes(TNTs)play important roles in cell-cell signaling and mass exchanges.However,a lack of powerful tools to visualize dynamic TNTs with high temporal/spatial resolution restricts the exploration of their formation and cleavage,hindering the complete understanding of its mechanism.Herein,we present the first example of using stochastic optical reconstruction microscopy(STORM)to observe the tube-like structures of TNTs linking live cells with an easily prepared fluorescent dye.Because of this new imaging microscopy,the cleavage process of TNTs was observed with a high spatial resolution.

关键词： super-resolution tunneling nanotubes(TNTs) live cell

Enhanced thermoelectric properties of n-type Bi_(2)O_(2)Se by KCl doping

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Journal of Advanced Ceramics 2023年第9期12卷 1767-1776页

作者： Zi-long Zhang Tao Wang Mohammad Nisar Yue-xing Chen Fu Li Shuo Chen Guang-xing Liang Ping Fan Zhuang-hao Zheng Shenzhen key laboratory of Advanced Thin Films and Applications Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Bi_(2)O_(2)Se is considered one of the most promising thermoelectric(TE)materials for combining with p-type BiCuSeO in a TE module given its unique chemical and thermal stability.However,the enhancement of its dimensionless figure of merit,zT value,remains a challenge because of its low electrical conductivity.Herein,we introduce KCl into Bi_(2)O_(2)Se,synthesized by solid-state reaction and spark plasma sintering method,to improve its TE properties.The synthesized samples show an outstanding enhancement in electrical conductivity,carrier concentration,and power factor after KCl doping.The Bi_(2)O_(2)Se-based sample with a 0.05%KCl doping content possesses a high zT value of~0.58 at 773 K,which is over 50%enhancement compared with the pristine Bi_(2)O_(2)Se sample.We also prove that the K element substitutes the Bi site,and Cl replaces the Se site by X-ray diffraction results and density functional theory calculation,supporting that K can improve the electrical conductivity by the position of Fermi level which is above the conduction band minimum.Experimental and theoretical results indicate the success of co-doping with a small amount of KCl and show a huge potential of this novel method for Bi_(2)O_(2)Se TE performance improvement.

关键词： thermoelectric(TE)materials Bi_(2)O_(2)Se KCl co-doping figure of merit(zT)

Intermolecular hydrogen-bonding as a robust tool toward significantly improving the photothermal conversion efficiency of a NIR-II squaraine dye

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Chinese Chemical Letters 2024年第4期35卷 310-315页

作者： Songtao Cai Liuying Wu Yuan Li Soham Samanta Jinying Wang Bing Liu Feihu Wu Kaitao Lai Yingchao Liu Junle Qu Zhigang Yang Center for Biomedical Photonics&Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

The photothermal therapy(PTT) has come across as a promising noninvasive therapeutic strategy for tumor treatment. However, low photothermal conversion efficiency(PCE) and hydrophobicity may impede the therapeutic efficacy of organic photothermal agents and an efficient PTT-agent must overcome these two major challenges. In this work, we developed a new strategy to promote higher PCE wherein the intermolecular hydrogen-bonding interaction between the single dye molecule and water facilitated the transformation of the absorbed energy into the heat. A hydrophilic squaraine dye(SCy1) with the second near-infrared region(NIR-II) absorption and extremely low emission were designed to exhibit much higher PCE than that of the analogues of pentamethine-dyes(PCy1, PCy2). The presence of the ‘–O-' at middle of squaric cycle enabled the intermolecular H-bonding formation between the SCy1 and water to promote the energy dissipation channel. Moreover, the introduction of long-chain phenylsulfonate groups helped in to improve the water solubility apart from serving as an additional means of further enhancing PCE through fluorescence quenching. Therefore, SCy1 with a squaraine backbone and long-chain sulfonate moieties revealed outstanding photothermal stability and anti-aggregation activity apart from showing exceptionally high PCE(74%) in water. SCy1 demonstrated excellent therapeutic efficacy when applied in the PTT treatment of tumor-bearing mice under a laser irradiation of 915 nm.

关键词： Squaraine-based cyanine Hydrogen bonds High PCE Anti-aggregation Photothermal therapy

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用于人机交互的应力发光光纤传感器（英文）

Science Bulletin 2023年第6期 542-545页

作者：任碧赟陈冰张鲜辉武红磊傅愉彭登峰 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic Engineering Shenzhen University

Luminescent materials convert various types of energy (e.g.,light radiation, electromagnetic radiation/electric field, and mechanical stimulus) into light emissions, resulting in a multitude of luminescence processes called photoluminescence (PL), electroluminescence (EL), and mechanoluminescence (ML)(Table S1 online). Due to the intriguing photophysical properties of these luminescent materials, they are widely developed and applied in many fields such as information security, energy harvesting, light sources and displays, infrastructure health monitoring, electronics,

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Realizing high thermoelectric performance in n-type Bi_(2)Te_(3)based thin films via post-selenization diffusion

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Journal of Materiomics 2023年第4期9卷 618-625页

作者： Yue-Xing Chen Jun-Ze Zhang Mohammad Nisar Adeel Abbas Fu Li Guang-Xing Liang Ping Fan Zhuang-Hao Zheng Shenzhen key laboratory of Advanced Thin Films and Applications Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060China

Thermoelectric thin film has attracted a lot of attention due to its potential in fabricating micropower generator in chip sensors for internet of things(IoT).However,the undeveloped performance of n-type thermoelectric thin film limits its widely application.In this work,a facile post-selenization diffusion reaction method is employed to introduce Se into Bi_(2)Te_(3)thin films,in order to optimize the carrier transport properties.Experimental and theoretical calculation results indicate that the carrier concentration decreases and density of states increases after Se doping,leading to the enhancement of Seebeck coefficient.Further,adjusting the diffusion reaction temperature can maintain the carrier concentration while increasing the mobility simultaneously,resulting in a high power factor of 1.5 mW/(m·K^(2)),which is eight times higher than that of the pristine Bi_(2)Te_(3)thin films.Subsequently,a thin film device fabricated by the present Se-doped Bi_(2)Te_(3)thin films shows the highest output power of 60.20 nW under the temperature difference of 37 K,indicating its potential for practical use.

关键词： Thermoelectric Thin film Magnetron sputtering Bie-Tee-Se

Simple phase extraction in x-ray differential phase contrast imaging

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Chinese Physics B 2016年第2期25卷 563-567页

作者：刘鑫郭金川雷耀虎李冀牛憨笨 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic Engineering Shenzhen University

A fast and simple method to extract phase-contrast images from interferograms is proposed, and its effectiveness is demonstrated through simulation and experiment. For x-ray differential phase contrast imaging, a strong attenuation signal acts as an overwhelming background intensity that obscures the weak phase signal so that no obvious phase-gradient information is detectable in the raw image. By subtracting one interferogram from another, chosen at particular intervals,the phase signal can be isolated and magnified.

关键词： x-ray imaging x-ray interferometry Talbot and self-imaging effects phase contrast imaging