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<i>In situ</i> study of the film formation mechanism of organica??inorganic hybrid perovskite solar cells: controlling the solvate phase using an additive system
摘要： As a coating method compatible with printing, one-step spin-coating is widely used for fabricating perovskite thin films. Controlling the crystal growth rate of two precursors is essential to obtain a homogeneous film morphology. However, the film formation mechanism and role of solvate systems during spin-coating have not yet been clearly revealed. In this work, we implemented the in situ grazing incidence wide-angle X-ray scattering of CH3NH3PbI3 perovskite material based on various additive systems to adjust the unbalanced crystal growth rate of CH3NH3I and PbI2. As we expected, the behavior of the solvate phase was strikingly mediated by various additives, and one of the additives greatly slowed the PbI2 solvate phase, thus overcoming the imbalance in the crystal growth rate. Consequently, the well-controlled perovskite films have both good film morphology and high photovoltaic performance with excellent reproducibility.
关键词： in situ study,solvate phase,perovskite solar cells,film formation mechanism,additive system
更新于2025-09-23 15:21:01
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Experimental Observation of Ultrafast THz Absorption Modulation in a Graphene-Based Metasurface
摘要： Magnetorheological (MR) fluid is a widely used smart material due to its outstanding properties. This paper presents the design, development, modeling, and prototype testing of a self-energizing and self-powered MR brake-by-wire system, whose aforementioned capabilities are enabled by brake energy harvesting. The system is composed mainly of a typical T-shaped drum-type MR brake and a wedge mechanism for self-energizing purpose. Into the system, we also install a generator that harvests regenerative energy during braking, thereby creating a self-power capability that cannot be found in common vehicular brake-by-wire systems. Brake torque analysis is conducted, and the braking process is simulated in a MATLAB/Simulink environment. Finite element analysis of the magnetic field, temperature field, and mechanical strength of critical components is carried out. The simulation results are used to optimize design parameters and material selection. Finally, prototypes and a corresponding test rig are established. The experimental results show that only about 30 W of power is required to generate a 315 N·m brake torque and that the regenerative power produced by the generator can be used for braking, thus fulfilling the self-power requirement. The investigation of different wedge angles indicates that considerable self-energizing occurs under a small wedge angle. The findings demonstrate that the brake actuator, which has a relatively small volume, can significantly enlarge brake torque while harvesting brake energy. This feature enables the promising application of MR fluids in automotive brake systems.
关键词： magnetorheological (MR),wedge mechanism,energy harvesting,Brake-by-wire system,self-powered capability
更新于2025-09-23 15:21:01
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[IEEE 2020 International Conference on Computing, Networking and Communications (ICNC) - Big Island, HI, USA (2020.2.17-2020.2.20)] 2020 International Conference on Computing, Networking and Communications (ICNC) - On Performance of Multiuser Underwater Wireless Optical Communication Systems
摘要： This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated power cycling test setup is given. Then, an improved in situ junction temperature estimation method using on-state collector–emitter voltage VC E O N and load current is proposed. In addition, a procedure of advanced accelerated power cycling test and test results with 600 V, 30 A transfer molded IGBT modules are presented in order to verify the validity and effectiveness of the proposed apparatus and methodology. Finally, physics-of-failure analysis of tested IGBT modules is provided.
关键词： power cycling test,physics-of-failure,Failure mechanism,lifetime model,insulated-gate bipolar transistor module,reliability
更新于2025-09-23 15:21:01
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Peripheral RAFT Polymerization on a Covalent Organic Polymer with Enhanced Aqueous Compatibility for Controlled Generation of Singlet Oxygen
摘要： A covalent organic polymer (COP) is prepared by 4,4’,4’’,4’’’-(porphyrin-5,10,15,20-tetrayl)tetraaniline (TAPP) with 4,4’-(anthracene-9,10-diyl)dibenzoic acid (ADDA) via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/4-dimethylaminopyridine coupling. The COP is further modified with a hydrophilic polymer, poly(poly(ethylene glycol) methyl ether methacrylate) by grafting-from reversible-addition-fragmentation chain transfer (RAFT) polymerization to enhance its solubility in various solvents. The modified COP can bind singlet oxygen through the formation of endoperoxide by ADDA upon the exposure to red light irradiation. Singlet oxygen can be then released via the photodynamic mechanism or the cycloreversion by endoperoxide when heated at 110 8C. These results open new possibilities for simultaneous generation of singlet oxygen by the photodynamic route and singlet oxygen carriers, demonstrating promise for treating hypoxic tumors.
关键词： endoperoxides,grafting-from,covalent organic polymers,singlet oxygen,photodynamic mechanism
更新于2025-09-23 15:21:01
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Additive-controlled synthesis of monodisperse single crystalline gold nanoparticles: interplay of shape and surface plasmon resonance
摘要： We introduce a three-step seed-mediated synthesis for single crystalline gold nanoparticles (Au NPs) stabilized by hexadecylpyridinium chloride (CPC) in variable sizes with an adjustable ratio of the cubic and octahedral facets. The effect of KBr and ascorbic acid (AA) on shape and growth kinetics is systematically investigated. The kinetic data were evaluated using the minimalistic Finke-Watzky autocatalytic two-step mechanism, which allows to estimate the rate constants of the “pseudoelementary” reactions. The proposed surface-mediated mechanism of reduction of gold ions and Au NPs growth allows to explain the effect of gradual increase of bromide ion concentration on switching the Au NPs morphology from cubic to octahedral. The plasmonic properties of single particles of different facetings and their assemblies are investigated.
关键词： gold nanoparticles,Finke-Watzky mechanism,plasmonic properties,seed-mediated synthesis,surface plasmon resonance
更新于2025-09-23 15:21:01
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Enhanced UV and visible light - driven Photocatalytic degradation of Tartrazine by Nickel-doped Cerium oxide Nanoparticles
摘要： Nickel-doped cerium oxide nanoparticles were synthesized via a simple aqueous coprecipitation method. The synthesized nanoparticles were thoroughly characterized by PXRD, TEM, SEM, EDX, Raman, and UV-Vis spectroscopic techniques. XRD study confirmed the doping of nickel in the cerium oxide lattice. The shift in Raman spectra revealed the formation of nanoparticles in their pure phase with fluorite structure. EDX revealed the formation of a solid solution on doping Ni- to CeO2. SEM images revealed considerable agglomeration. TEM analysis asserted the average particle size of 8-10 nm with a well-defined spherical shape. The particle size was found to be sensitive to dopant concentration, i.e., it decreased with increase in the concentration of the dopant. A comparative UV-visible spectroscopic analysis showed the remarkable red shift in the band gap of nickel-doped cerium oxide nanoparticles. Investigation of photocatalytic activity towards degradation of azo dye tartrazine showed that 3 mol% and 5 mol% Ni- CeO2 nanoparticles exhibited 53.4% and 63.7% photodegradation respectively under visible irradiation while 57.4% and 65.4% respectively under UV irradiation. The study suggests that the band gap of cerium oxide nanoparticles can be easily tuned (decreased) by doping of nickel at different concentrations. The observed improved photocatalytic activity upon Nickel doping is attributed to the narrow band gap.
关键词： azo dye,mechanism,tartrazine,photocatalysis,Nickel-doped cerium oxide nanoparticles
更新于2025-09-23 15:21:01
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Interface Kinematics of Laser Impact Welding of Ni and SS304 Based on Jet Indentation Mechanism
摘要： With the application of high-velocity impact welding (HVIW) technology, the research on the mechanism of the formation and evolution of interface waveforms has become an important research direction in HVIW. Understanding the mechanism of interface motion can help control and improve HVIW. Laser impact welding (LIW), a branch of HVIW, lacks research on the formation and evolution of interface waveforms. Therefore, LIW experiments of Ni and SS304 are carried out. The jet indentation mechanism and the smoothed particle hydrodynamics method are used to simulate and analyze the formation and evolution of the LIW interface waveform. Results show that the interface materials exhibit ?uid behavior during LIW. The jet indentation mechanism can explain the formation and evolution of waveforms in LIW. Jet velocity, normal stress, and ?yer horizontal welding speed are the main factors a?ecting the variation of the interface waveform size in LIW. At the collision point, the smaller the horizontal welding speed of the ?yer, the larger the wavelength; the smaller the jet velocity, the smaller the amplitude. In addition, the propagation of the normal stress deviating from each other at the welding interface along the welding direction is the fundamental cause of springback and cracking.
关键词： SS304,Ni,Laser impact welding,Smoothed particle hydrodynamics,Jet indentation mechanism,Interface waveforms
更新于2025-09-23 15:21:01
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New insights into the release mechanism of Cd2+ from CdTe quantum dots within single cells in situ
摘要： Cadmium-quantum dots (Cd-QDs) possess unique properties as optoelectronic devices for sensitive detection in food and biomedicine fields. However, the toxic effects of Cd-QDs to single cells is still controversial, due to the release mechanism of QDs to Cd2+ in situ and the cytotoxic effects of QDs and Cd2+ respectively are still unclear. In this paper, the release rule of Cd2+ from CdTe QDs within single cells was investigated in situ by using flow cytometry method and the dose-response relationships were explored. Besides, an all-inclusive microscopy system was optimized for live cell imaging to observe the real-time entry process of CdTe QDs into cells. We found that intracellular CdTe QDs and Cd2+ contents were increased based on the dosage and exposing time. A dissociated saturation of Cd2+ from CdTe QDs was exist within cells. CdTe QDs induced more serious cyto-toxicity on kidney cells than hepatocytes. The toxicity of oxidative stress, cell apoptosis effects induced by CdTe QDs and Cd2+ are also in consistent with this result. This research develops analytical method to quantify the uptake and release of Cd-QDs to primary cells in situ and can provide technical support in studying the cyto-toxicity portion contributed by nanoparticles (NPs) and metal ions.
关键词： Release mechanism,Aqueous phase QDs,Single cells,Cd,In situ
更新于2025-09-23 15:21:01
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Type-II heterojunction constructed by Ag2S-coupled ZnO microspheres with visible light-responsive antibacterial activity
摘要： ZnO nanorods-assembled microspheres were photosensitized with a layer of low bandgap Ag2S nanoparticles on the branched nanorods to get a type-II core/shell heterojunction (ZnO@Ag2S). The heterojunction with unique band configuration exhibited better visible light-responsive antibacterial activity than pure ZnO, which is attributed to the inhibition of photocarrier recombination and efficient charge separation and transfer. Scavenger test confirmed that the photoinactivation of bacteria was directed by the (cid:1) radicals and photogenerated holes. The growth of Gram-negative bacteria was more effectively restrained by ZnO@Ag2S than that of Gram-positive bacteria and fungi because of structural difference of cell walls.
关键词： ZnO@Ag2S,Composite materials,Mechanism,Semiconductors,Photocatalytic activity
更新于2025-09-23 15:21:01
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Assessing the Performance of Cobalt Phthalocyanine Nanoflakes as Molecular Catalysts for Li-Promoted Oxalate Formation in Li–CO <sub/>2</sub> –Oxalate Batteries
摘要： Removal of O2 molecules from the cathode environment in the Li-based battery has led to introduction of the Li?CO2 battery as the novel and promising source of energy storage. In spite of CO2 capture through the reversible reaction between Li atoms and CO2 molecules at the cathode, the performance of the Li?CO2 battery is hampered by formation of the Li2CO3 insulating product in the discharge process and its di?cult decomposition in the charging process. Hereby, we explore the possible improvement of the performance of the Li?CO2 battery through replacement of Li2CO3 by Li2C2O4 as the discharge product. This is achieved by systematic addition of Li and CO2 to a cobalt phthalocyanine (CoPc) nano?ake employed as the molecular catalyst in the cathode of the Li?CO2 battery by means of computational density functional theory-based methods. The present results predict high adsorption energy of the CO2 molecules (?2.16 eV), low Li-intercalation voltage (1.45 V), reveal the important and constructive in?uence of the electrolyte (dimethyl sulfoxide) on the adsorption and decomposition energies and Li-intercalation voltage, and suggest a through-space electron transfer mechanism for the formation of the Li2C2O4 product on the CoPc nano?ake. Moreover, the high electron a?nity of the CoPc nano?ake along with the suitable thermodynamics and kinetics of electron transfer from the CoPc nano?ake to the CO2 molecules during the formation of the Li2C2O4 product con?rm the potential abilities of the CoPc nano?ake to be used in the Li?CO2 battery. Therefore, present results provide a sound assessment of the capability of the CoPc nano?ake as a cathode material in the Li?CO2 battery and show that this provides a possible and e?ective solution to improve the performance of the Li?CO2 battery and to introduce new Li?CO2?oxalate batteries.
关键词： Li?CO2 battery,cobalt phthalocyanine,electron transfer mechanism,density functional theory,molecular catalyst
更新于2025-09-23 15:21:01