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Formation of Si Hollow Structures as Promising Anode Materials through Reduction of Silica in AlCl <sub/>3</sub> –NaCl Molten Salt
摘要： Hollow nanostructures are attractive for energy storage and conversion, drug delivery, and catalysis applications. Although these hollow nanostructures of compounds can be generated through the processes involving the well-established Kirkendall effect or ion exchange method, a similar process for the synthesis of the pure-substance one (e.g., Si) remains elusive. Inspired by the above two methods, we introduce a continuous ultrathin carbon layer on the silica nano/microstructures (St?ber spheres, diatom frustules, sphere in sphere) as the stable reaction interface. With the layer as the diffusion mediator of the reactants, silica structures are successfully reduced into their porous silicon hollow counterparts with metal Al powder in AlCl3?NaCl molten salt. The structures are composed of silicon nanocrystallites with sizes of 15?25 nm. The formation mechanism can be explained as an etching?reduction/nucleation?growth process. When used as the anode material, the silicon hollow structure from diatom frustules delivers specific capacities of 2179, 1988, 1798, 1505, 1240, and 974 mA h g?1 at 0.5, 1, 2, 4, 6, and 8 A g?1, respectively. After being prelithiated, it retains 80% of the initial capacity after 1100 cycles at 8 A g?1. This work provides a general way to synthesize versatile silicon hollow structures for high-performance lithium ion batteries due to the existence of ample silica reactants and can be extended to the synthesis of hollow structures of other materials.
关键词： carbon interface,hollow structures,silicon,molten salt,anode
更新于2025-09-23 15:21:01
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Rhenium and technetium-complexed silicon rhodamines as near-infrared imaging probes for bimodal SPECT- and optical imaging
摘要： Fluorescent Si-rhodamines were modified to enable complexation with the Re(I)- and 99mTc(I)-tricarbonyl core. The corresponding complexes exhibit suitable properties as bimodal imaging probes for SPECT- and optical imaging in vitro. Importantly, the novel in aqueous solution stable, functionalized Si-rhodamines retain favourable optical properties after complexation (QY=0.09, λabs=654 nm, λem=669 nm in PBS) and show promising near-infrared optical properties for potential in vivo applications enabling bimodal scintigraphic imaging and optical imaging, e.g. used in radio- and fluorescence-guided tumor resection.
关键词： SPECT,Optical imaging,Near-infrared imaging,Technetium,Rhenium,Silicon rhodamines
更新于2025-09-23 15:21:01
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Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer
摘要： In this work, to ameliorate the quantum e?ciency (QE), we made a valuable development by using wide band gap material, such as lithium ?uoride (LiFx), as an emitter that also helped us to achieve outstanding e?ciency with silicon heterojunction (SHJ) solar cells. Lithium ?uoride holds a capacity to achieve signi?cant power conversion e?ciency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium ?uoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also bene?cial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band o?set to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion e?ciency (PEC) of 23.74%, ?ll factor (FF) of 82.12%, Jsc of 38.73 mA cm?2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer.
关键词： electric ?eld,silicon heterojunction solar cell,lithium ?uoride,electron selectivity contact layer,work function
更新于2025-09-23 15:21:01
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Silicon wafer etching by pulsed high-power inductively coupled Ar/CF <sub/>4</sub> plasma with 150 kHz band frequency
摘要： A silicon wafer etching using a burst pulse high-power inductively coupled plasma (ICP) is investigated. A 200 μs wide burst of a 157 kHz power supply is employed to generate ICP with a repetition rate of 50 Hz. A rectangular pulsed voltage synchronized with the burst power supply is applied upto 1 kV at the wafer. Mixed gas of argon (Ar) and tetrafluoromethane (CF4) is supplied into the vacuum chamber. The plasma density and electron temperature are 1019 m?3 and 2.8 eV where the wafer is, respectively. In the case of Ar plasma, the silicon etching rate is 0.01 μm min?1 with 1000 V negative bias. The etching rate increases to 0.23 μm min?1 by adding CF4 into Ar and increases linearly with increasing the bias voltage. The target current and emission intensity of Ar+ and F* are depended on bias voltage from ?300 to ?1000 V. The etching rate sharply increases by increasing CF4 content from 0% to 10%, and it becomes almost constant at 10%. The dependency of emission intensity of F* on CF4 content is similar to the dependency the etching rate.
关键词： Ar/CF4 plasma,high-power inductively coupled plasma,silicon wafer etching,150 kHz band frequency
更新于2025-09-23 15:21:01
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25.1% Higha??Efficient Monolithic Perovskite Silicon Tandem Solar Cell with a High Band Gap Perovskite Absorber
摘要： Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum band gap, high quantum efficiency, and high stability of the perovskite. Here, we combine a silicon heterojunction bottom cell with a perovskite top cell with an optimum band gap of 1.68 eV in planar p-i-n tandem configuration. Methylammonium-free FA0.75Cs0.25Pb(I0.8Br0.2)3 perovskite with high Cs-content is investigated for improved stability. A 10% molarity increase to 1.1 M of the perovskite precursor solution resulted in ~75 nm thicker absorber layers and 0.7 mA/cm2 higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of ~80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over five months showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved anti-reflection measures, the high band gap perovskite absorber has the potential for 30% tandem efficiency in the near future.
关键词： interfaces,heterojunction silicon solar cells,perovskite solar cells,thin films,tandem solar cells
更新于2025-09-23 15:21:01
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A high performance method for the accurate and precise determination of silicon isotopic compositions in bulk silicate rock samples using laser ablation MC-ICP-MS
摘要： MC-ICP-MS has become one of the most powerful analytical methods for Si isotopes in bulk liquid and solid samples in the past decade. Laser ablation provides direct sampling of solid samples, avoiding laborious chemical digestion procedures. As for powder bulk samples, the preparation of stable and homogeneous targets prior to measurements, and strategies to minimize potential matrix effects, are critical for accurate isotopic analysis. In this study, an accurate and precise method for Si isotope ratio measurements by fs-LA-MC-ICP-MS of bulk silicate rock samples was established. A new laser fusion sample preparation technique was developed to achieve fast and homogeneous fusion of silicate rock powders (including granite and granodiorite that contain abundant refractory minerals) into glasses. Compared to the pressed pellet technique, the measurement precision for fused glasses was improved ~5.7-fold. Matrix effects during Si isotopic analysis were observed when using non-matrix matched calibration protocols under normal dry-plasma instrument conditions with both ns- and fs-laser using a raster ablation mode. Matrix effects were eliminated by the addition of water vapor into the plasma, realizing accurate non-matrix matched calibration. In addition, fs-laser provided better measurement precisions, with the internal and external precisions being improved ~1.85 and ~2.4 fold compared to ns-laser at nearly equal signal intensities. Five well characterized silicate rock reference materials were analyzed using fs-LA-MC-ICP-MS calibrated against NBS-28 and BHVO-2G. Results obtained for =29Si and =30Si for these five reference materials were in agreement with previously reported values, confirming the accuracy of the proposed method.
关键词： matrix effects,Silicon isotopic analysis,water vapor addition,laser ablation MC-ICP-MS,silicate rock samples
更新于2025-09-23 15:21:01
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<i>Ab Initio</i> Spin-Strain Coupling Parameters of Divacancy Qubits in Silicon Carbide
摘要： Cubic silicon carbide is an excellent platform for integration of defect qubits into established wafer-scale device architectures for quantum information and sensing applications, where a divacancy qubit, which is similar to the negatively charged nitrogen-vacancy (NV) center in diamond, has favorable coherence properties. We demonstrate by means of density-functional-theory calculations that for most types of distortion the 3C divacancy exhibits slightly smaller spin-strain coupling parameters but greater spin-stress coupling parameters in comparison with the diamond NV. We predict that high-quality 3C-SiC thin films hosting divacancy qubits are prospective platforms for quantum-enhanced pressure-sensor devices.
关键词： spin-strain coupling,quantum sensing,density-functional theory,divacancy qubits,silicon carbide
更新于2025-09-23 15:21:01
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Design and fabrication of a high-precision 360?° laser receiver for leveling applications
摘要： The laser technique based sensors and actuators can provide many superior properties as noncontact, high sensitivity, remote operation, and reliable performance in contrast to other mechanical and electrical techniques. In this paper, we design and fabricate a high-precision 360(cid:1) laser receiver for leveling, especially for agricultural and construction field. The laser receiver is primarily composed of photoelectrical conversion module, electrical signal processing module, and display panel module. Based on the centroid method, the detection error of the laser receiver with respect to laser source and silicon photocell array, is analyzed and simulated. The design and fabrication process are described in detail, including the overall structure and electrical circuits. Furthermore, this fabricated laser receiver is demonstrated to be high precision through several static and dynamic tests in the distance of 10 and 50 m. Besides, this fabricated laser possesses wireless transmission function, which provides much convenient for users in remote operation.
关键词： leveling,silicon photocell,laser receiver,centroid method
更新于2025-09-23 15:21:01
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Argon clustering in silicon under low-energy irradiation: Molecular dynamics simulation with different Ar–Si potentials
摘要： In this paper, the authors carried out a molecular dynamics simulation of crystal and amorphous silicon sputtering by low-energy (200 eV) Ar ions at normal incidence. The gradual damage of silicon caused by the ion bombardment was taken into account in order to study the dynamics of argon accumulation and clustering. For describing interatomic Ar–Si interaction, they used three different potentials: two binary screened Coulomb potentials (Molière and Ziegler–Biersack–Littmark) and the potential developed on the basis of density functional theory. The obtained results demonstrated the substantial influence of the chosen Ar–Si potential on calculated sputtering yields and on the processes of argon accumulation and clustering.
关键词： silicon sputtering,molecular dynamics simulation,Ar–Si potentials,argon clustering,low-energy irradiation
更新于2025-09-23 15:21:01
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Laser ablation of silicon in water at different temperatures
摘要： Underwater laser machining process is an alternative method to cut materials with less thermal damage due to the water cooling of workpiece during the ablation. However, the rapid cooling induced by water can instantly solidify the laser-molten material rather than expel it to form a cut. To understand the roles of processing temperature on ablation performance in water, this paper presents the influences of water temperature on cut width, depth, and surface morphology in the underwater laser grooving of silicon. The effects of laser power, laser traverse speed, and number of laser passes on the groove characteristics were also examined in this work. The results revealed that using high water temperature can increase the groove aspect ratio, particularly when high laser power, slow traverse speed, and multiple laser passes were employed. However, debris deposition and oxides were found on the laser-ablated surface when processing at high water temperature. The implication of this study could enhance the ablation rate for the underwater laser as well as low-power laser cutting systems.
关键词： Laser,Silicon,Water,Ablation,Temperature
更新于2025-09-23 15:21:01