Variation Of Series Resistance Research Articles

Investigation of Interface States, Series Resistance and Barrier Height Variation with Frequency in Al/WO3/p-Si (MOS) Capacitors

In the study, Tungsten oxide (WO3) was synthesized via the sol-gel method on P-type 〈100〉 silicon wafer. Electrical characterization of the Al/WO3/p-Si (MOS) capacitor was performed through capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements at different frequencies (from 50 kHz to 1 MHz). As the applied voltage frequency increased, the maximum values of the measured C-V and G/ω-V characteristics decreased. This phenomenon was attributed to interface state trap (Dit) charges following low-frequency AC voltage signals. The variation of series resistance (Rs) and barrier height (ΦB) with frequency was examined. It was shown that Rs significantly affects the device behaviour. The ΦB also decreased with increasing frequency. This situation is suggested to indirectly affect the mobility of charge carriers directly through the Vo value. Ultimately, although WO3 material exhibits variable results in terms of dielectric properties, the study's finding of a high dielectric constant (e.g., 3688.75) is consistent with similar results in the literature. This high dielectric property underscores the material's importance for future applications.

Numerical simulation to optimize power conversion efficiency of an FTO/GO/Cs2AgBiBr6/Cu2O solar cell.

Efficient conversion of solar power to electrical power through the development of smart, reliable, and environmentally friendly materials is a key focus for the next-generation renewable energy sector. The involvement of degradable and toxic elements present in hybrid perovskites presents serious concerns regarding the commercial viability of these materials for the solar cell industry. In this study, a solar cell with a stable, nondegradable, and lead-free halide-based double perovskite Cs2AgBiBr6 as the absorber layer, Cu2O as a hole transport layer, and GO as the electron transport layer has been simulated using SCAPS 1D. The thickness of the absorber, electron transport, and hole transport layers are tuned to optimize the performance of the designed solar cell. Notably, perovskite solar cells functioned most efficiently with an electron affinity value of 4.0 eV for Cu2O. In addition, the effect of variation of series resistance and temperature on generation and recombination rates, current density, and quantum efficiency has been elaborated in detail. The findings of this study provide valuable insight and encouragement toward the realization of a non-toxic, inorganic perovskite solar device and will be a significant step forward in addressing environmental concerns associated with perovskite solar cell technology.

Performance enhancement of Sb2Se3 solar cell with IGZO and n-ZnO as electron transport layers

A prototype of an antimony (III) selenide (Sb2Se3) solar cell with different electron transport layers (ETLs) was simulated using the Solar Cell Capacitance Simulator (SCAPS) software. The impact of two individual ETLs – namely, indium gallium zinc oxide (IGZO) and n-type zinc oxide (n-ZnO) – was analyzed, and it was found out that n-ZnO was best for the ETL. The n-ZnO, antimony (III) selenide and Indium gallium zinc oxide (IGZO) layers in the newly proposed structure have respective thicknesses of 50, 300 and 20 nm. To achieve the optimum performance of this prototype, the acceptor concentration of copper (II) oxide is taken as 1018 cm−2 and the donor concentration of n-ZnO is taken as 1020 cm−2. The defect densities at antimony (III) selenide and antimony (III) selenide/n-ZnO are taken as 1013 and 1010 cm−2, respectively. They play a crucial part in device performance. With the optimized structure, a maximum power conversion efficiency of up to 31.72% (V OC = 1.148 V, J SC = 48.30 mA/cm2 and fill factor = 88.50%) is obtained with n-ZnO as the ETL. For effective results, the defect densities at both interfaces are taken as 109 cm−2, and maximum efficiency is achieved. Numerical analysis of the proposed structure and study of various parameters such as thickness variation at the absorber layer, series resistance and temperature variation, defect density, metal function and interface density variation were done.

Digital Impedance Bridge for Four-Terminal-Pair AC Resistor Calibration up to 20 kHz

For this study, a substitution principle-based impedance bridge has been developed to calibrate AC resistors in a four-terminal-pair (4TP) configuration. The calibration is performed in the full complex plane for resistances ranging from 100 mΩ to 400 Ω and frequencies of between 50 Hz and 20 kHz. The automated bridge is based on four resistors associated with two high-impedance stages. The balancing of the bridge is achieved by means of PXI modules. The bridge is automatically balanced via a simplex top-down algorithm. The new bridge is primarily used for the measurement chain of AC standard resistors defined in a 4TP configuration at LNE, which are used for routine customer calibrations. The traceability of LNE’s standard resistors when defined in a 4TP configuration is ensured by a measurement chain from a 1 kΩ reference resistor using the new bridge. The reference resistor was calibrated previously via comparison with a calculable resistor up to 20 kHz. The bridge was validated via comparison with calibration results obtained in 1983 and 2009. For a resistor of 1 Ω at 1 kHz, the uncertainty of the series resistance variation and the phase shift are less than 6 µΩ/Ω (k = 1) and 6 µrad (k = 1), respectively.

Unraveling the Potential Pathways for Improved Performance of EDA0.01(GA0.06(FA0.8Cs0.2)0.94)0.98SnI2Br‐Based Solar Cells

This article comprehensively investigates the photovoltaic performance of a 3% GeI2‐doped ASnI2Br absorber in a solar cell. The cell features an inverted structure (fluorine‐doped tin oxide [FTO]/poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate [PEDOT:PSS]/absorber/C60/Ag) and utilizes EDA0.01(GA0.06(FA0.8Cs0.2)0.94)0.98 as the A‐site cation (EDA for ethylenediamine; GA for guanidinium; FA for formamidinium). Through systematic numerical simulation and optimization, the photovoltaic performance of the solar cell is enhanced by sequentially optimizing several parameters: 1) absorber thickness and defect density, 2) conduction band offset at the ASnI2Br/C60 interface, doping of the electron‐transport layer (ETL), and its interface with the absorber, and 3) valence band offset at the PEDOT:PSS/ASnI2Br interface, and doping of the hole‐transport layer and its interface with the absorber. Additionally, the impact of series resistance (Rs) variation on device performance is investigated. Starting with an initial power conversion efficiency (PCE) of 4.86%, the systematic numerical optimization process elevates it to an impressive 18.55%. Furthermore, a final cell structure is proposed where C60 is replaced with indium‐doped tin oxide (ITO) as the ETL layer. This optimized FTO/PEDOT:PSS/absorber/ITO structure demonstrates a remarkable PCE of 18.68%. These findings hold significant promise for advancing tin‐perovskite solar cell technology.

Effect of Band‐Gap Tuning and Series Resistance on PCE of Optimized MAPbI3‐Based PSC by SCAPS‐1D Simulation

AbstractOrganic–inorganic metal halide‐based perovskite solar cell (PSC) is reaching more height day by day. Recent various efforts are applied by different researchers with experimental and theoretical studies to improve the device performance and stability of device. In the present work, MAPbI3‐based PSC device is stimulated to under its behavior with variation in the band‐gap of absorber and series resistance. The band‐gap of absorber is varied from 1.3 to 2.5 eV and it has found that the simulated exhibited superior PCE of 25.76% at band‐gap of 1.3 eV. Further, the variation in series resistance affects the device performance and found best device response under lower resistance. Additionally, the change in QE with variation in Rs is also analyzed.

Impedance Spectroscopy for Diagnosis of Photovoltaic Modules Under Outdoor Conditions

This work is aimed at detecting degradation phenomena on photovoltaic (PV) panels working under real outdoor conditions by using the impedance spectroscopy technique. The impedance is measured by leaving the PV panel in the real-operative status corresponding to the maximum power point without altering its power production. Since variations on the series resistance are associated with multiple degradation phenomena, this study seeks to estimate changes in this parameter using a dynamic model fitted to the experimental impedance measurements. An external resistor is added in series to the PV panel for emulating the degraded conditions. Hence, the PV panel impedance measurements are compared in nominal and degraded conditions. The results show that the dynamic model provides higher accuracy in comparison with the series resistance variation identified through the single-diode model, which is the most usual approach. Thus, it is demonstrated the feasibility of detecting degradation effects by using the dynamic model of PV panels working under outdoor conditions.

New impedance bridge at LNE for the two terminal-pair AC resistor calibration up to 20 kHz

This paper presents the evolution of LNE’s impedance bridge (Wheatstone bridge) used to calibrate AC resistors defined in the two terminal-pair configuration. A new automated Wheatstone bridge, based on four resistances, was developed to operate in the full complex plane for resistances ranging from 400 Ω to 2 MΩ and for frequencies up to 20 kHz. A commercial dual precision arbitrary waveform generator supplies the bridge and PXI modules achieve the balance. Phase and frequency synchronization solutions between the arbitrary waveform generator source and the PXI modules were used. The choice of these instruments allows the bridge to be easily automated and to benefit from recent progress in the development of digital-analog converters, in particular those with high frequency sampling rates and resolution. The bridge is mainly dedicated to realize the periodic calibration of LNE’s standard resistors, used for routine customer calibrations. The traceability of LNE’s standard resistors is ensured, firstly, by the calibration of a 1 kΩ resistor by comparison to a calculable resistor up to 20 kHz. Then, this resistor is used as a reference element to ensure the traceability of all LNE’s standard resistors using the new bridge. The validation was done by comparing the results obtained, for some resistors with very low drift, with those obtained during calibrations performed in 1983, 1995 and 2009. For resistors of 1 kΩ in a 1:1 ratio, the expanded uncertainty of series resistance variation and argument are, respectively, less than 1.3 µΩ Ω−1 (k = 1) and 1.2 µrad (k = 1), up to 20 kHz.

Equivalent models of solar photovoltaic cells and discuss the effects of resistance on maximum output power curve

The usage of renewable energy for power generation plays a key role in power sector through reduces the noxious impacts of conventional fuels to generate power. Solar photovoltaic is a clean and emission-free renewable energy sources which is widely used for the power generation in the world. The solar photovoltaic array is made up of solar modules. These modules are act as an interfacing unit. The conversion process from sunlight to electricity is obtained through modules. But, the generation of power through involving the solar photovoltaic is dependent on variation of environments. The solar photovoltaic arrays have non-linear characteristics and depend on available solar insolation and operating temperature. A problem can be raised if these cells have not synchronized with each other. The variation of series resistance can cause the more absorption of current by the leakage current resistance. Due to this, a substantial reduction of current flows through the load circuit. So, the variation in shunt (parallel) resistance and series resistance can obtained a significant change in output characteristics. The data sheet provided by manufacturer of solar photovoltaic module contains current-voltage (I-V) and power-voltage (P-V) characteristics. The datasheet contains various parameters of solar module. But there are some parameters not provided in the datasheet by the manufacturer. This paper presents the effect of series resistance (Rs) and parallel resistance (Rp) on solar photovoltaic characteristics curves. The variation in characteristics curve (or maximum power output curve) well shown by the graphical representations.

Effect of parasitic resistances on CdTe solar cell and validation with datasheet of FS-6450A in Matlab/Simulink

Cadmium telluride (CdTe) is the second popular choice after silicon for the solar cell in photovoltaic (PV) technology. Among the thin-film photovoltaic panels, CdTe reaches its first position to surpass crystalline silicon PV in cheapness and confined a large space in the PV market. Before constructing CdTe PV panels its operating characteristics should be properly judged. Any solar cell being related to a high level of nonlinearity, the model parameter is to be chosen judiciously. The operating characteristics can be well considered after the model circuit parameter comes accurately. In this paper operating characteristics of a thin-film CdTe solar module is shown with the variation of series and shunt resistance. Also considering parasitic resistances, the output characteristics of the solar cell varying climate condition is shown. Validation with FS-6450A PV module and all the simulation works are done in Matlab/Simulink environment. In the end, it is concluded with possible outcomes.

Investigating the viability of PERC solar cells fabricated on Ga- instead of B-doped monocrystalline silicon wafer

The viability of commercial Ga-doped silicon PERC solar cell is decided by its efficiency, cost and reliability. In this article, the viability of Ga-doped Cz-Si PERC solar cells has been investigated systematically from an industrial perspective. Firstly, the relationship of wafer resistivity, contact fraction and variation of series resistance for PERC solar cell has been established for increasing the usage rate of Ga-doped crystal. Then, based on the relationship, an average efficiency of 22.21% for the PERC cells with five busbars fabricated from the whole Ga-doped CZ crystal has been achieved. The statistical results of electrical parameters show that the PERC cells fabricated on Ga-doped Cz-Si wafers with a wide resistivity variation (0.5–2.0 Ω⋅cm) are highly comparable with that of PERC cells made from B-doped Cz-Si wafers with typical resistivity (0.5–1.0 Ω⋅cm). The obtained results demonstrated that the full range of resistivity values produced from a Ga-doped Cz crystal can be used to fabricate quality, cost-effective PERC solar cells. Meanwhile, a comparative study of initial degradation for optimized Ga-doped PERC solar cells and stabilized B-doped PERC solar cells was carried out in accumulative irradiation of 20 kWh/m2 at 50 °C and 80 °C. The results indicate that Ga-doped PERC cells are more stable than stabilized B-doped PERC cells even though at high temperature. The results obtained in this paper demonstrate the viability of Ga- instead of B-doped Cz-Si wafer as substrate to fabricate cost-effective PERC solar cells.

The Reliability Analysis of PV Panels Installed in KP Region

Reliability and long term performance of photovoltaic (PV) system is of vital importance in switching from conventional sources to sustainable one. Design, study and analysis of key components in a photovoltaic power system starting from generation of power to withstands number of climatic stresses and uninterrupted power supply plays a key role. One of the key elements in photovoltaic system is photovoltaic module. Also power generated in photovoltaic system is dependent on a source of energy that changes in every instant and with the passage of time during its operation .Hence it is paramount to build a long lasting photovoltaic module and analyze characteristics of the PV module under various conditions. This paper presents an efficient PV module based on PV equivalent circuit model using MATLAB/Simulink, and compared the simulated model results with manufacturer’s specifications like peak current, peak voltage, open circuit voltage and short circuit current .Also the performance of the module under variation of series resistance, irradiation, and temperature are analyzed. Data from five different areas across KP are noted and the results were Simulated and compared with the rated data.

Reliability Modeling for Metallized Film Capacitors Based on Time-Varying Stress Mission Profile and Aging of ESR

Metallized film capacitor (MFC) is one of the key components in power electronic converters, accounting for a large proportion of failures. However, the time-varying external stress in long-term mission profile and time-varying internal stress due to the degradation of MFC are not well described by the conventional reliability evaluation method, which leads to a large deviation between the evaluation results and the engineering practices. Therefore, an improved reliability evaluation method considering time-varying stress mission profile and aging process for MFC is proposed. First, this article analyzes the influence of harmonics and provides a more accurate lifetime model under constant stress condition, compared with the conventional method. Second, the subsection integral accumulated damage model is proposed to transform the long-term time-varying stress mission profile to the short-term ideal constant stress condition, solving the reliability evaluation under time-varying external stress condition. And then, an improved aging model is proposed to describe the nonlinear variation of equivalent series resistance (ESR) and internal temperature rise due to the degradation process of MFC. Furthermore, Monte Carlo simulation is applied to analyze the difference of individual capacitor, obtaining lifetime distribution. Finally, a practical application example of modular multilevel converter (MMC) system is implemented to verify the superiority of the improved method.

Solar photovoltaic module performance characterisation using single diode modeling

Single or double diode electrical modeling of SPV module gives valuable results which will help to identify the exact behavior of SPV module under the normal operating condition. Accurate modelling of SPV module will also help to calculate internal resistances (Rs, Rsh) and parasitic of the SPV module. The main contribution of this work is the stepwise simplification of the current equation of single and double diode electrical model of SPV module. Then the single diode model of SPV module having 36 SPV cells in series is simulated in LTspice simulator. Simulated results are compared with labelled electrical parameters which shows close proximity to the labelled parameter at particular values of series and shunt resistance. This paper also presents the effect of variation in series resistance (Rs) and shunt resistance (Rsh) on the performance of the SPV module under normal operating condition. The dependency of SPV electrical parameters (Imax, Vmax, Pmax, FF, η) with the variation of series resistance (Rs) and shunt resistance (Rsh) is simulated, and the effects are discussed in details.

Optimization Design of a Multibusbar Structure: The Using of a Conductive Belt

An interconnect electrode called conductive belt was applied to modules instead of interconnection ribbons. The conductive belt has multiple wires and can achieve a multibusbar structure by forming ohmic contacts with the cell electrodes. The following problems were studied with innovative approaches to optimize the multibusbar modules: the shading rate and the contact resistance of the conductive belts, the relationship between the finger series resistance and the wire number, and the influence of the series resistance variation on the maximum power output. Furthermore, the wire number and diameter were optimized according to the following conditions: the cell sizes were full, half, and one-third, and the finger wet weights of a full cell were 80 mg, 40 mg, and 20 mg. The result showed that multibusbar and half-cell structures could achieve the maximum power output, the wire number was 16 and the wire diameter was 200 μm, and the finger wet weight was reduced to 20 mg. Finally, the reliability of the modules made with conductive belts was tested and was qualified according to International Electrotechnical Commission standards.

Prognostics of aluminum electrolytic capacitors using artificial neural network approach

In this work, an effort is being made to monitor the condition of in-circuit aluminum electrolytic capacitor using artificial neural network (ANN). Recent industrial surveys on the reliability of power electronic systems shows that most of faults occur due to the wear out of aluminum electrolytic capacitors and thermal stress is the major cause for its parametric degradation. The condition of target capacitors can be estimated by monitoring variation in equivalent series resistance (ESR) from the initial pristine state value. ANN is used to estimate ESR of pristine and weak target capacitors at the test conditions. The data set for training and testing of proposed back-propagation trained artificial neural network are experimentally obtained from the developed test bed. Using the test bed, target capacitors are subjected to different operating frequency and temperature in the output section of DC/DC buck converter circuit to determine the effect of variation in electrical and thermal stress on ESR value. After off-line training, the proposed ANN is implemented using National Instruments LabVIEW software. A low cost microcontroller is programmed for real time data acquisition of target capacitors and the serial transmission of acquired dataset to the LabVIEW software installed at host computer. The performance of the proposed method is evaluated in real time by comparing the resulting ESR with the experimental values of in-circuit target capacitors. The proposed ANN, once trained properly, can be used for different circuits and in different operating conditions because of its generalization capability.

Answer to comments on “Fabrication and photovoltaic conversion enhancement of graphene/n-Si Schottky barrier solar cells by electrophoretic deposition”

Here, we reply to comments by Valentic et al. on our paper published in Electrochimica Acta (2014, 130: 279). They commented that Au nanoparticles played the dominant role on the whole cell's performances in our improved graphene/Si solar cell. We argued that our devices are Au-doped graphene/n-Si Schottky barrier devices, not Au nanoparticles (film)/n-Si Schottky barrier devices. During the doping process, most of the Au nanopatricles covered the surfaces of the graphene. Schottky barriers between doped graphene and n-Si dominate the total cells properties. Through doping, by adjusting and tailoring the Fermi level of the graphene, the Fermi level of n-Si can be shifted down in the graphene/Si Schottky barrier cell. They also argued that the instability of our devices were related to variation in series resistance reduced at the beginning due to slightly lowered Fermi level and increased at the end by the self-compensation by deep in-diffusion of Au nanoparticles. But for our fabricated devices, we know that an oxide layer covered the Si surface, which makes it difficult for the Au ions to diffuse into the Si layer, due to the continuous growth of SiO layer on the Si surface which resulted in series resistance decreasing at first and increasing in the end.

Enhanced thermal stability of reduced graphene oxide-Silicon Schottky heterojunction solar cells via nitrogen doping

We investigated the thermal stability and electrical properties of nitrogen-doped reduced graphene oxide (NrGO)/n–type Si solar cells. A NrGO layer was used as a transparent electrode as well as an electron-hole separation layer simultaneously. The effect of doping on the carbon and nitrogen bonding configurations in NrGO was investigated using X–ray photoelectron spectroscopy (XPS). The XPS data indicate that pyridinic–N is the dominant bonding configuration. This bonding configuration leads to a reduction in the power conversion efficiency and a decrease in the short circuit current. However, on being subjected to thermal oxidation, the NrGO/n–type Si solar cells exhibit a smaller variation in series resistance compared to the undoped rGO/Si solar cells. Results of accelerated thermal tests suggest that nitrogen doping prevents re-oxidation of the reduced graphene oxide layer.

Drain current local variability from linear to saturation region in 28 nm bulk NMOSFETs

In this work, we investigate the impact of the source - drain series resistance mismatch on the drain current variability in 28nm bulk MOSFETs. For the first time, a mismatch model including the local fluctuations of the threshold voltage (Vt), the drain current gain factor (β) and the source – drain series resistance (RSD) in both linear and saturation regions is presented. Furthermore, it is demonstrated that the influence of the source – drain series resistance mismatch is attenuated in the saturation region, due to the weaker sensitivity of the drain current variability on the series resistance variation. The experimental results were further verified by numerical simulations of the drain current characteristics with sensitivity analysis of the MOSFET parameters Vt, β and RSD.

Analysis of electrical parameters of InGaN-based LED packages with aging

As the light-emitting diode (LED) becomes a mature technology in the general illumination space, there is a tendency to operate LEDs at high current densities and temperatures in order to gain higher light output at lower cost. Further, there is interest among intelligent-lighting platform developers to offer predictive maintenance capabilities to users. The existing useful life prediction model defines LED lifetime based on parametric failure; however, there is a need for a useful life prediction model based on catastrophic failure, which can occur with the degradation of components in an LED package. Electrical parameters, especially package series resistance, are good indicators of LED package health (i.e., remaining useful life) and could potentially be sensed real-time in an application. In this study, the series resistance variation pattern until catastrophic failure was measured at different current and temperature stress conditions. The degradation mechanisms at each phase of variation were explained and, using available models, activation energies and exponents were extracted. The experimental data suggest electromigration-induced metal migration from the contact metallization layer to the semiconductor is the cause of short circuit catastrophic failure of LED packages. The variation patterns of ideality factor and reverse leakage current support this hypothesis. The information presented can be used to develop a catastrophic life estimation model for LED packages under current and temperature stress.