Current Voltage Research Articles

Highly efficient 2D transition metal Dichalcogenides/SnSe solar cells using Sb2S3 as a back surface field and interfacial layer engineering

Boosting the performance of solar cells is crucial for advancing photovoltaic technology. This study investigates the integration of alternative 2D materials to enhance the performance of solar cells. Three solar cell configurations sample 1 with CdS, sample 2 with MoS2, and sample 3 with SnS2 are systematically investigated via numerical simulation. The simulation framework is validated against experimental data, demonstrating good agreement. Alternative 2D materials are explored to replace toxic CdS and improve the Voc through suitable band alignment with the absorber material, SnSe. Additionally, Sb2S3 is introduced as a back surface field (BSF) for the first time, resulting in increased efficiencies across all three samples. Further performance enhancements involve the insertion of 2D interfacial layers between the electron transport layer (ETL) and absorber to mitigate interface defects. Thirteen materials are evaluated as interfacial layers and nine metals as back contacts, revealing Ni as the optimal back contact for all samples, while MoS2, SnS2, and WS2 are identified as suitable interfacial layers for samples 1, 2, and 3, respectively. Analysis of the solar cells reveals that sample 2, incorporating MoS2 and SnS2, achieves the highest efficiency at 13.58 %. This outperforms sample 3 at 13.55 % and sample 1 at 13.13 %. Sample 2′s superior performance is attributed to the effective utilization of 2D transition metal dichalcogenide (TMDC) materials, which enhance charge carrier transport and minimize recombination losses within the cell structure. Optimized solar cell configurations are modeled using a one-diode approach to build corresponding modules. These modules, created by connecting solar cells in series and parallel, are evaluated through simulated I-V characteristics and power output under standard test conditions. Analysis reveals that Module 2 exhibits superior performance, with higher short-circuit current (ISC) and open-circuit voltage (VOC) compared to Modules 1 and 3. Overall, this study demonstrates the significant role of 2D TMC materials in advancing solar cell performance, providing valuable insights for future solar energy applications.

Electrical Performance and Degradation Analysis of Field-Aged PV Modules in Tropical Climates: A Comparative Experimental Study

Performance degradation is a prevalent phenomenon in solar photovoltaic systems globally, with varying aging profiles and effects depending on environmental and climatic conditions. This paper presents an extensive investigation of the electrical performance, aging mechanisms, and degradation analysis of field-aged PV modules under the tropical climate of Malaysia. Utilizing a combination of visual inspection, I-V curve measurement, and thermal imaging techniques, this research provides a comprehensive assessment of the electrical and thermal properties of field-aged PV modules from two locations in Malaysia over extended periods (8 years at UMPSA and 10 years at Pasir Mas). The multi-faceted approach of the study allows for a deeper understanding of the degradation process, offering insights into the causes and effects of higher current and lower voltage in aged modules. The study found the average annual degradation rates at UMPSA were 0.3% for open circuit voltage (Voc), 0.23% for short circuit current (Isc), 0.81% for maximum power (Pmax), and 0.35% for fill factor (FF) and at Pasir Mas, the average annual degradation rates were 1.124% for Voc, −0.166% for Isc, 1.276% for Pmax, and 0.43% for FF. The study also found that monocrystalline silicon (m-Si) panels experienced an average power degradation of 6.48%, while polycrystalline silicon (p-Si) panels showed a higher degradation of 12.76%. However, Thermal imaging revealed significant temperature variations across the modules, with hotspots reaching up to 11.2 °C above cooler areas in UMPSA panels and an even more pronounced 26.1 °C difference in Pasir Mas modules. These temperature disparities highlight the uneven heat distribution and potential performance issues in the panels. This research contributes to the understanding of PV module degradation in tropical climates and aligns with sustainable development, climate change mitigation efforts, and SDG 7 by promoting sustainable energy solutions.

Quasi Z source direct matrix converter based K- to three-phase wind energy conversion system using maximum constant boost current control modulation technique

The conversion system for wind energy has no restriction on the number of output phases. K numbers of output phases can be converted into standard grid-connected three-phase supply using a quasi-Z source direct matrix converter (QZSDMC). The obtained input supply may be five phases from the wind energy conversion system with continuously variable frequency as well as variable terminal voltages. Using the proposed QZSDMC converter with maximum constant boost current control modulation technique constant three-phase voltages as well as frequency can be maintained at the grid side. Additionally, the energy conversion system has high output voltage gain. The proposed converter as well as the modulation technique produces the maximum voltage transfer ratio of 1.05. The output voltage gain reached nearly 1.99 compared with the traditional power converters. The voltage THD and current THD are maintained within the acceptable limit of 5.3 and 3.6 respectively. The power factor have been maintained nearly unity throughout the all mode of operations. To stabilize the grid frequencies and grid voltages additional control blocks are used. This research article presents simulation results for the proposed QZSDMC converter with a maximum constant boost current control modulation technique. Also, the proposed scheme has been validated with suitable experimental results.

Adaptive linear active disturbance-rejection control strategy reduces the impulse current of compressed air energy storage connected to the grid

The merits of compressed air energy storage (CAES) include large power generation capacity, long service life, and environmental safety. When a CAES plant is switched to the grid-connected mode and participates in grid regulation, using the traditional control mode with low accuracy can result in excess grid-connected impulse current and junction voltage. This occurs because the CAES output voltage does not match the frequency, amplitude, and phase of the power grid voltage. Therefore, an adaptive linear active disturbance-rejection control (A-LADRC) strategy was proposed. Based on the LADRC strategy, which is more accurate than the traditional proportional integral controller, the proposed controller is enhanced to allow adaptive adjustment of bandwidth parameters, resulting in improved accuracy and response speed. The problem of large impulse current when CAES is switched to the grid-connected mode is addressed, and the frequency fluctuation is reduced. Finally, the effectiveness of the proposed strategy in reducing the impact of CAES on the grid connection was verified using a hardware-in-the-loop simulation platform. The influence of the k value in the adaptive- adjustment formula on the A-LADRC was analyzed through simulation. The anti-interference performance of the control was verified by increasing and decreasing the load during the presynchronization process.

The CRILIN calorimeter: gamma radiation resistance of crystals and SiPMs

The Crilin calorimeter is a semi-homogeneous calorimetric system based on Lead Fluoride (PbF2) crystals with UV-extended Silicon Photomultipliers (SiPMs) proposed for the Muon Collider. This study investigates the radiation resistance of crystals and SiPMs, subjected to 10 kGy gamma irradiation, equivalent to a 10-year service life in the Muon Collider. Our findings indicate that while PbF2 crystals exhibit a decrease in transmittance post-irradiation with partial recovery over time, the alternative PbWO4-Ultra Fast (PWO-UF) demonstrates exceptional radiation hardness, maintaining stable transmittance. SiPMs showed an increase in dark current and breakdown voltage post-irradiation, with less degradation observed in the SiPM biased during the exposure to radiation compared to the unbiased component. These results underscore the viability of PbF2 for radiation-tolerant calorimeters, though improvements in production homogeneity are needed. The superior performance of PWO-UF crystals suggests they are a promising alternative for high-radiation applications, but their higher cost must be carefully considered.

A simple hot wire temperature drift correction based on temperature sensitivity applied to a turbulent shear layer

A procedure is proposed to correct temperature drift for hot wire anemometry measurements in turbulent fields where the facility is not equipped with temperature control. The procedure consists of evaluating the wire sensitivity to the temperature by building a voltage-temperature curve. The voltages of both the calibration points and the measurement points are corrected, shifting the voltage values to an arbitrary reference temperature. The correction can be applied to the instantaneous voltages by performing synced temperature measurements with constant current anemometry or constant voltage anemometry cold wire. The efficacy of the method is tested on a turbulent shear layer that develops on the side of an open jet wind tunnel not equipped with temperature control. The velocity statistics show a good match with respect to reference particle image velocimetry measurements, evidencing the self-similarity of the shear layer in contrast with the non-corrected data and the data corrected using the semi-empirical and analytical relation based on King's law modification. A correction based only on the temperature statistics shows indistinguishable results with respect to the instantaneous correction.

Investigating the ions emitted by multiply charged ionic liquids from a porous electrospray ion source

A porous electrospray ion source was tested with three ionic liquids in order to investigate the effects of ionic liquid properties on the sizes of ion clusters emitted by purely ionic electrospray sources. Two of the ionic liquids, bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate and 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide, were selected due to them having a dication or dianion, which were termed multiply charged ionic liquids due to them containing anions or cations with more than one charge within them. These were selected in order to investigate ionic clustering within electrospray ion emission and were compared against one of the most common ionic liquids, EMI-BF4. The current–voltage data showed that EMI-BF4 emitted similar levels of current to bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate, even though the latter liquid had significantly lower conductivity and higher viscosity, suggesting an improvement in current speculated to be due to the extra charges contained by the ions. Time-of-flight and retarding potential analysis data are provided, showing all three liquids emitting ions comprising of monomers, dimers, trimers, and quadramers, with some of the 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide data showing heavier species emission. The data also suggested that the multiply charged ionic liquids produced ions that have two anions or cations attached, termed “double ions,” with these ions not been previously reported using porous electrospray sources. Furthermore, it was found that the dimers emitted by both of the multiply charged ionic liquids seemed to be more stable than EMI-BF4 dimers, providing insight into ion cluster formation.

Influence of gate work function variations on characteristics of fin-shaped silicon quantum dot device with multi-gate under existence of gate electrostatic coupling

We explored the effects of gate work function variation (WFV) through device simulation on a fin-shaped silicon quantum dot device with a multi-gate configuration for a large-scale integrated array. The threshold voltage (Vth) of current–voltage characteristics is affected by WFV in both main and surrounding gates, indicating the existence of electrostatic coupling among these gates. The electrostatic coupling can be reduced by biasing on the surrounding gates. Furthermore, the concept of Vth, following conventional transistors, works as a reference of voltage and potential in the present multi-gate device. This knowledge contributes to establishing a practical method for the statistical analysis of qubit variability.

Empowering energy conservation: A prototype of household energy consumption monitoring based on Internet of Things

Abstract One of the obstacles to control household energy consumption is unavailability electricity instruments/tools to monitor electricity energy consumed by appliances causing a lack of awareness of household energy saving. Energy meter installed on buildings only show electricity consumption in total. This study aims to design and create a prototype system that can monitor and control the electrical appliances usage utilizing the Internet of Things (IoT)-based electronic devices where electricity usage data is stored in Firebase real-time database. The methods carried out are arranged in several stages, starting from data collection, design, configuration, and implementation. The tools used in this research will utilize the ESP8266 as the microcontroller, the PZEM-004T as current sensor and the Blynk as the web server. The tool will send current voltage (Volt (V)) and capacity (Watt (W)) data and then converted to energy and also the costs incurred from electricity usage based on the basic electricity tariff of National Electricity Company (PLN) and the results can be seen directly through IoT (i.e. smartphone, PC, laptop). The accuracy of power measurement by the system is 97.4% compared to measurement used by watt-checker. The results of this study show that an electrical power monitoring system makes people easier to monitor electrical power consumption by appliances used. The pilot measurement shows that a unit system can monitor electricity usage for four units of electronic equipment i.e. water pump, Television, fridge, electrical iron, rice cooker, etc. precisely and succeeded to control and increase energy saving awareness to reduce electricity consumption at the end.

Synergistic optimization of nonlinear current–voltage characteristics and dielectric properties in Mg-doped CaCu3Ti4O12-Y2/3Cu3Ti4O12 composites

Synergistic optimization of nonlinear current–voltage characteristics and dielectric properties in Mg-doped CaCu3Ti4O12-Y2/3Cu3Ti4O12 composites

Electrodeposition of graphene oxide on titanium foil. Application field: Rechargeable batteries

The method of electrodepositing graphene oxide on titanium utilizes a thin grade 1 titanium foil with a thickness of 0.2 mm, a width of 10 mm, and a rectangular graphite plate with a parallelepiped shape with a thickness of 15 mm, a width of 40 mm, and a length of 100 mm. The titanium foil has a cut on one side, forming an isosceles triangle with a slightly inclined tip, creating an angle where the distance between the tip and the vertical symmetry axis of the foil is 3 mm. The titanium foil is positioned parallel to the graphite plate, with the tip as the only electrical contact. The two electrodes, titanium and graphite, assembled in this way, are immersed in an electrolytic solution composed of water and sulfuric acid. When a direct current voltage is applied between the two electrodes, a strong electric field is generated at the contact point, resulting in high temperature and the production of ultraviolet rays. Following a treatment described later in the so-called “preparation protocol,” reduced graphene oxide (rGO) is produced in suspension in the solution at the contact point between the tip of the titanium foil and the graphite plate, which, due to the electric field, tends to deposit on the titanium surface. A possible application found experimentally refers to rechargeable batteries.

High-current, high-voltage AlN Schottky barrier diodes

AlN Schottky barrier diodes with low ideality factor (<1.2), low differential ON-resistance (<0.6 mΩ cm2), high current density (>5 kA cm−2), and high breakdown voltage (680 V) are reported. The device structure consisted of a two-layer, quasi-vertical design with a lightly doped AlN drift layer and a highly doped Al0.75Ga0.25N ohmic contact layer grown on AlN substrates. A combination of simulation, current–voltage measurements, and impedance spectroscopy analysis revealed that the AlN/AlGaN interface introduces a parasitic electron barrier due to the conduction band offset between the two materials. This barrier was found to limit the forward current in fabricated diodes. Further, we show that introducing a compositionally-graded layer between the AlN and the AlGaN reduces the interfacial barrier and increases the forward current density of fabricated diodes by a factor of 104.

A data-driven model for the field emission from broad-area electrodes

Electron emission from cathodes in high field gradients is a quantum tunneling effect. The 1928 Fowler–Nordheim field emission (FE) equation and the 1956 Murphy–Good FE equation have traditionally been key in describing cold field emissions, offering estimates for emitters for almost a century. Nevertheless, applying FE theory in practice is often constrained by the lack of data on the distribution and geometry of the emission sites. Predictions become more challenging with an uneven electric field distribution at the cathode surface. Consequently, FE formulations are frequently calibrated using current–voltage data after test, limiting their efficacy as true predictive models.This study develops an alternative model for field emission using a data-driven predictive approach based on (1) vast experimental data, (2) electrostatic simulations of the cathode surface, and (3) detailed material and geometry properties, which together overcome these limitations. The objective of this work is to develop and harness this comprehensive dataset to train a machine learning model capable of providing precise predictions of the cathode current in order to further the understanding and application of field emission phenomena. More than 259 h of experimental data have been processed to train and benchmark some of the well-known machine learning models. After two stages of optimization, a coefficient of determination >98% is achieved in the prediction total field emission current using ensemble models.

Strain detection based on magnetic domain wall motion in amorphous FeSiBNb thin film

The strain dependence of the pulse voltage induced in a pickup coil originating from the domain wall motion in an amorphous FeSiBNb thin film was investigated. No significant change in the peak pulse voltage was observed when tensile strain was applied to the thin film, whereas the peak pulse voltage changed steeply when compressive strain was applied. In addition, strain susceptibility could be controlled via appropriate annealing. Evaluation of the strain gauge comprising the amorphous FeSiBNb thin film, a pickup coil, an electrical circuit (which converts the pulse voltage into direct current voltage), and a Helmholtz coil revealed that strain gauge has a notably high gauge factor of approximately 37,500.

Ultrasound-enabled adaptive protocol for fast charging of lithium-ion batteries

Abstract This paper introduces an ultrasound-assisted multi-stage constant current (UA-MSCC) charging protocol to enhance the charging performance of lithium-ion batteries. In this approach, ultrasound is applied during the final portion of each multi-stage constant current (MSCC) charging phase. Experimental results demonstrate that ultrasound decreases the internal resistance of pouch cells by up to 7%, leading to significant increase in charging capacity during each MSCC stage. The overall charging time is reduced by 26% compared to the conventional constant current constant voltage (CCCV) protocol. The performance improvement delivered by this ultrasound-assisted charging approach is especially large when the battery is charged at low temperatures and to a partial capacity. Notably, the application of ultrasound improves the coulombic efficiency to levels comparable to that at the room temperature when charging in cold environments (0°C). This approach can be applied to commercial batteries to immediately improve their charging performance, and can be seamlessly integrated into battery management systems. Unlike approaches that necessitate electrode material modifications or electrolyte additives, which require a long development time, this UA-MSCC charging protocol offers a practical and easily applicable solution for improving the battery charging performance.

Quasi‐Z‐source interleaved DC‐DC converter for fuel cell vehicle application

AbstractIn this study, a step‐up DC‐DC converter with a combination of a two‐phase interleaved structure and a quasi‐Z impedance network is proposed for fuel cell vehicle application. The operation of the converter in a small duty cycle (0 &lt; D &lt; 0.5) reduces the conductive losses of the switches and as a result increases the efficiency of this converter compared to conventional boost converters. Also, due to the common ground between the input and output, unlike the floating interleaved boost converter (FIBC) and the parallel input‐series output converter (PISO), it does not face the problem of imposing additional EMI on the converter circuit. This converter has a low input current ripple, suitable voltage gain for fuel cell vehicles system, as well as high reliability due to the ability to operate with one phase in case of failure in the other phase. It can be a suitable candidate for practical application in fuel cell vehicles. The principles of operation and the main characteristics of the converter such as voltage gain, input current ripple, and voltage and current stress of the elements are explained and also a 120‐W experimental prototype with 12‐V input voltage and 60‐V output voltage is made to validate the theoretical analysis results.

Influence of WEDM input variables on the machinability of Ni–Cu superalloy

ABSTRACT The study investigates the influence of Wire-cut Electrical Discharge Machining (WEDM) input variables on the Ni–Cu superalloy, crucial in marine environments. Input variables include Input current (Ic), Pulse on Time (TON), Pulse off Time (TOFF), Servo Voltage (SV), and Wire Feed (WF) rate, while output variables are Machine Speed (Mc), Kerf Width (K), and Material Removal Rate (MRR). Utilizing an L16 orthogonal matrix, experiments were conducted. The Taguchi method examines single output variables, while the Grey Relational Grade Algorithm (GRA) assesses multi-objective outputs. GRA identifies optimal input combinations, crucial for maximizing the machining performance. ANOVA of GRA results highlights Pulse on Time (TON), Input current (Ic), and Servo Voltage (SV) as significant factors affecting Mc, K, and MRR. This analysis underscores their importance in optimizing the WEDM process for Ni–Cu (MONEL K-500 superalloy).

A Comprehensive Flow–Mass–Thermal–Electrochemical Coupling Model for a VRFB Stack and Its Application in a Stack Temperature Control Strategy

In this work, a comprehensive multi-physics electrochemical hybrid stack model is developed for a vanadium redox flow battery (VRFB) stack considering electrolyte flow, mass transport, electrochemical reactions, shunt currents, and as heat generation and transfer simultaneously. Compared with other VRFB stack models, this model is more comprehensive in considering the influence of multiple factors. Based on the established model, the electrolyte flow rate distribution across cells in the stack is investigated. The distribution and variation in shunt currents, single-cell current and single-cell voltage are analyzed. The distribution and variation in temperature and heat generation and heat transfer are also researched. It can be found that the VRFB stack temperature will exceed 40 °C when operating at 60 A and 100 mA cm−2 at an ambient temperature of 30 °C, which will lead to electrolyte ion precipitation, affecting the performance and safety of the battery. To control the stack temperature below 40 °C, a new tank cooling control strategy is proposed, and the suitable starting cooling point and the controlled temperature are specified. Compared with the common room cooling strategy, the new tank cooling strategy reduces energy consumption by 27.18% during 20 charge–discharge cycles.

Characterization of neutron-irradiated SiPMs down to liquid nitrogen temperature

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The SiPMs were also annealed at high temperatures and re-characterized after the annealing. For the SiPM characterization in all the cases, current–voltage (I-V curve) measurements, dark count rate measurements, and waveform analysis, including single photon time resolution, were carried out at different controlled temperature steps from room temperature down to the liquid nitrogen temperature. 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With sufficient cooling, the measured single photon time resolution was around 90 ps FWHM for all irradiation levels.

200 mm Wafer Level Characterization at 2 K of Si/SiGe Field-Effect Transistors

Si/SiGe has proven to be an excellent spin qubit platform, but industrial production of large-scale spin-qubit chips is missing. We use field effect transistors (FETs) to monitor and develop the quality of the fabrication process on 200 mm wafers at 2 K using a cryogenic wafer prober (CWP). This mass-characterization technique provides statistics on device performance. We observe variations in drain off current and gate threshold voltage of 213 FETs. These variations are related to bias voltage conditions during CWP cooldown, which differ from qubit chip cooldown. To address this, a new FET structure with an additional top gate is introduced, effectively suppressing unintentional charge accumulations. This eliminates drain off currents and improves homogeneity of FET characteristics at 2 K. Our results highlight significant impact of bias conditions during qubit chip cooldown, which, if not accounted for in the qubit chip design, can lead to incorrect conclusions when using CWP.