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- 2018
- electron-transparent membranes
- micropump
- field emission electron source
- ion source
- ion mobility spectrometry
- Optoelectronic Information Science and Engineering
- Wroclaw University of Science and Technology
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Effect of Si substrate modification on improving the crystalline quality, optical and electrical properties of thermally-evaporated BaSi2 thin-films for solar cell applications
摘要： We have grown orthorhombic barium disilicide (BaSi2) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time te on crystalline quality as well as optical and electrical properties of the BaSi2 films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the BaSi2 thin-films. The te of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the BaSi2 film at te of 8 s were 38 mA/cm2, 273 cm2/Vs, and 2.3 μs, respectively. These results confirm that the BaSi2 thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.
关键词： hall mobility,substrate modification,photoresponse,silicide semiconductor,Barium disilicide,minority carrier lifetime,optical property,thermal evaporation
更新于2025-09-19 17:13:59
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Core-Shell ZnO@SnO2 Nanoparticles for Efficient Inorganic Perovskite Solar Cells
摘要： The ideal charge transport materials should exhibit a proper energy level, high carrier mobility, sufficient conductivity, and excellent charge extraction ability. Here, a novel electron transport material was designed and synthesized via using a simple and facile solvothermal method, which is composed by the core-shell ZnO@SnO2 nanoparticles. Thanks to the good match between energy level of SnO2 shell and high electron mobility of core ZnO nanoparticles, the PCE of inorganic perovskite solar cells has reached 14.35% (JSC: 16.45 mA cm-2, VOC: 1.11 V, FF: 79%), acting core-shell ZnO@SnO2 nanoparticles as the electron transfer layer. The core-shell ZnO@SnO2 nanoparticles size is 8.1 nm with the SnO2 shell thickness of 3.4 nm, and the electron mobility is seven times more than SnO2 nanoparticles. Meanwhile, the uniform core-shell ZnO@SnO2 nanoparticles is extremely favorable to the growth of inorganic perovskite films. These preliminary results strongly suggest the great potential of this novel electron transfer material in high-efficiency perovskite solar cells.
关键词： inorganic perovskite solar cells,electron transport material,solvothermal method,core-shell ZnO@SnO2 nanoparticles,high electron mobility
更新于2025-09-19 17:13:59
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Structural and electronic properties of liquid, amorphous, and supercooled liquid phases of In <sub/>2</sub> Te <sub/>5</sub> from first-principles
摘要： In2Te5 is a stoichiometric compound in the In–Te system of interest for applications in phase change electronic memories and thermoelectrics. Here, we perform a computational study of the structural, dynamical, and electronic properties of the liquid, supercooled liquid, and amorphous phases of this compound by means of density functional molecular dynamics simulations. Models of the supercooled liquid and amorphous phases have been generated by quenching from the melt. The structure of the liquid phase is characterized by a mixture of defective octahedral and tetrahedral local environments of In atoms, while the amorphous phase displays a mostly tetrahedral local geometry for In atoms with corner and edge sharing tetrahedra similar to those found in the crystalline phases of the In2Te5, InTe, and In2Te3 compounds. Comparison with our previous results on liquid and amorphous In2Te3 and further data on the structural properties of liquid In2Te3 are also discussed. The analysis of the electronic properties highlights the opening of a mobility gap in In2Te5 at about 150 K below the liquidus temperature.
关键词： electronic properties,In2Te5,structural properties,mobility gap,density functional molecular dynamics,phase change materials
更新于2025-09-19 17:13:59
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Accurately Stoichiometric Regulating Oxidation States in Hole Transporting Material to Enhance the Hole Mobility of Perovskite Solar Cells
摘要： In the traditional n-i-p type perovskite solar cells (PSCs), most hole transporting materials (HTMs) rely on an uncontrolled oxidative process by using Li salt and Co (III) complex to achieve sufficient hole mobilities. Herein, we demonstrate a stabilized oxidized-phenothiazine-based HTM (OPTZ) synthesized from its neutral form (NPTZ) through a photo-redox reaction. This controllable and stable oxidation state is mainly derived from the planar structure and π-conjugation of phenothiazine core in OPTZ. The energy gap between SOMO (singly-occupied-molecular-orbital) of OPTZ and HOMO (highest-occupied-molecular-orbital) of NPTZ can suitably promote the hole hopping in hole transporting layers. Using an optimized ratio of OPTZ as dopant in NPTZ, the hole transporting mobility is effectively enhanced owing to intra- and inter-molecular charge transfer process, resulting in an enhancement in the fill factor of the PSCs. This work can provide a new strategy to obtain stabilized oxidized-HTMs, which deliver significantly enhanced hole mobilities of HTMs in PSCs.
关键词： phenothiazine,hole transport material,hole mobility,perovskite solar cell,radical cation
更新于2025-09-19 17:13:59
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Solution-processable porous organic polymer for tailoring the charge transport property of planar perovskite solar cells
摘要： Herein, a soluble, highly branched, and cross-linked polymer was prepared with alkyl-modified perylene and melamine motifs by adapting the synthetic strategy for porous organic polymers (T-POP). With the expanded surface area of such a polymer relative to the linear one-dimensional conjugated polymers, the intermolecular contact between the optically active units such as perylene motifs in the back bones or branches increased in frequency, resulting in strong π-π stacking, which facilitated the charge charrier transport in planar perovskite solar cells. Additionally, its amorphous nature afforded a smooth surface without severe aggregation, which typically limits the continuous charge carrier pathways. However, the films showed rough surface morphology when the substrates such as indium tin oxide glass with high hydrophilic property were used, while the films showed smooth surfaces when it was deposited on PC70BM, which was one of the device components. Furthermore, by comparing its frontier orbital levels with those of the other components in the devices, it was confirmed that T-POP could be applied as a secondary electron transport layer on the PC70BM layer. As a result, the stability of the perovskite layer increased with a concomitant increase in the hydrophobicity of the top layer with T-POP and the power conversion efficiencies of the functioning devices increased up to 13% with respect to the devices without T-POP enhancing electron transport efficacy.
关键词： Perovskite solar cells,Electron mobility,Electron transport,Interlayer,Porous organic polymer
更新于2025-09-19 17:13:59
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Directional Beam Based LED Deployment for a Short Range Indoor LED Light Communication System
摘要： There is now an increasing awareness about the possibility of health hazards due to excessive electromagnetic radiations around us within the indoor environment. Hence, the alternative communication technologies such as indoor mobile communication system based on LED lighting are gaining more attention in the present scenario. The dual use of LEDs i. e. for illumination as well as for setting up of an indoor communication network infrastructure simultaneously makes it an attractive preposition. The LED lighting based communication system is qualified to be part of green technology networks. This paper investigates the optimal LED placement strategy for such a system to optimize the overall communication system parameters including the transmit power optimization. It is observed that the overall optimization of LEDs improve the signal to noise ratio and also a significant reduction in root mean square delay at lower semi-angle values besides improving the mobile coverage area.
关键词： root mean square delay,LED lighting based communication system,mobility,communication coverage area,signal to noise ratio
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Emission from an Asymmetric Dual-Grating-Gate InGaAs High-Electron-Mobility Transistor Stimulated by Plasmonic Boom Instability
摘要： Asymmetric dual-grating-gate InGaAs high-electron-mobility transistors (ADGG-HEMTs) are studied as plasmonic terahertz (THz) emitters. We experimentally observed THz emission from a fabricated device at 110K. The spectra showed a broadband resonant emission under low d.c. channel currents reflecting radiation decay of thermally excited plasmons. With increasing the current and longitudinal electric field the emission was enhanced in a narrower spectral range suggesting promotion of plasmonic instability. Its threshold behavior suggests the occurrence of plasmonic-boom-type instability.
关键词： terahertz emission,plasmonic instability,asymmetric dual-grating-gate,high-electron-mobility transistors,InGaAs
更新于2025-09-16 10:30:52
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Laser ionization ion mobility spectrometric interrogation of acoustically levitated droplets
摘要： Acoustically levitated droplets have been suggested as compartmentalized, yet wall-less microreactors for high-throughput reaction optimization purposes. The absence of walls is envisioned to simplify up-scaling of the optimized reaction conditions found in the microliter volumes. A consequent pursuance of high-throughput chemistry calls for a fast, robust and sensitive analysis suited for online interrogation. For reaction optimization, targeted analysis with relatively low sensitivity suffices, while a fast, robust and automated sampling is paramount. To follow this approach, in this contribution, a direct coupling of levitated droplets to a homebuilt ion mobility spectrometer (IMS) is presented. The sampling, transfer to the gas phase, as well as the ionization are all performed by a single exposure of the sampling volume to the resonant output of a mid-IR laser. Once formed, the nascent spatially and temporally evolving analyte ion cloud needs to be guided out of the acoustically confined trap into the inlet of the ion mobility spectrometer. Since the IMS is operated at ambient pressure, no fluid dynamic along a pressure gradient can be employed. Instead, the transfer is achieved by the electrostatic potential gradient inside a dual ring electrode ion optics, guiding the analyte ion cloud into the first stage of the IMS linear drift tube accelerator. The design of the appropriate atmospheric pressure ion optics is based on the original vacuum ion optics design of Wiley and McLaren. The obtained experimental results nicely coincide with ion trajectory calculations based on a collisional model.
关键词： Ion mobility spectrometry,Acoustic levitation,Ambient pressure laser ionization,Ion optics
更新于2025-09-16 10:30:52
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Resonance Instability of Photovoltaic E-Bike Charging Stations: Control Parameters Analysis, Modeling and Experiment
摘要： This article presents an in-situ comparative analysis and power quality tests of a newly developed photovoltaic charging system for e-bikes. The various control methods of the inverter are modeled and a single-phase grid-connected inverter is tested under different conditions. Models are constituted for two current control methods; the proportional resonance and the synchronous rotating frames. In order to determine the influence of the control parameters, the system is analyzed analytically in the time domain as well as in the frequency domain by simulation. The tests indicated the resonance instability of the photovoltaic inverter. The passivity impedance-based stability criterion is applied in order to analyze the phenomenon of resonance instability. In conclusion, the phase-locked loop (PLL) bandwidth and control parameters of the current loop have a major effect on the output admittance of the inverter, which should be adjusted to make the system stable.
关键词： grid-connected inverter,photovoltaic,solar mobility,resonance instability,power quality,solar charging
更新于2025-09-16 10:30:52
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Epitaxial growth and characterization of high quality Bi<sub>2</sub>O<sub>2</sub>Se thin films on SrTiO<sub>3</sub> substrates by pulsed laser deposition
摘要： Recently, Bi2O2Se is discovered as a promising two-dimensional (2D) semiconductor for next generation electronics, due to its moderate bandgap size, high electron mobility and pronounced ambient stability. Meanwhile, it has been predicted that high quality Bi2O2Se-related heterostructures may possess exotic physical phenomena, such as piezoelectricity and topological superconductivity. Herein, we report the first successful heteroepitaxial growth of Bi2O2Se films on SrTiO3 substrates via pulsed laser deposition (PLD) method. Films obtained under optimal conditions show an epitaxial growth with the c axis perpendicular to the film surface and the a and b axes parallel to the substrate. The growth mode transition to three dimensional (3D) island is observed as prolonging deposition time of films. The maximum value of electron mobility reaches 160 cm2/V-1s-1 at room temperature in a 70 nm-thick film. The thickness dependent mobility provides evidence that interface-scattering is likely to be the limiting factor for the relatively low electron mobility at low temperature, implying that the interface engineering as an effective method to tune the low temperature electron mobility. Our work suggests the epitaxial Bi2O2Se films grown by PLD are promising for both fundamental study and practical applications.
关键词： Bi2O2Se,pulsed laser deposition,heterostructure,high mobility,two-dimensional materials
更新于2025-09-16 10:30:52