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Modelling solar cellsa?? S-shaped I-V characteristics with an analytical solution to lumped-parameter equivalent circuit model
摘要： In this paper, an analytical solution to three-diode lumped-parameter equivalent circuit model is proposed to simulate and present S-shaped I-V characteristics of next generation solar cells, which are observed frequently in perovskite and organic solar cells, and occasionally in other kinds of solar cells. In general, because complicated transcendental equation includes three exponent items resulting from three diodes, the absence of an analytical solution has become a bottleneck that limits the adoptions of solar cells’ three-diode lumped-parameter model into practical applications and device simulations. To break through the above bottleneck, the analytical solution is derived in the regional approach, completed in Matlab platform, and verified by reconstructed experimental data measured from real solar cells. Such an analytical solution processes the key feature with high precise and efficiency. High precise results from the mathematical operations of the analytical solution to lumped-parameter model and high efficiency results from the avoidance of numerical iteration methods. In addition, this analytical solution facilitates researchers to accurately determine short circuit current and open circuit voltage, quickly extract model parameters in lumped-parameter circuit, and in detail assess effects from model parameters on DC characteristics of solar cells. Finally, the proposed analytical solution is able to be used to reproduce S-shaped I-V characteristics of solar cells, assist in extracting fitting parameters in three-diode lumped-parameter equivalent circuit model, and complete implementation of model into semiconductor device and circuit simulators.
关键词： Lumped-parameter equivalent circuit model,S-shaped I-V characteristics,Solar cells,Analytical solution
更新于2025-09-19 17:13:59
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[IEEE 2019 8th International Symposium on Next Generation Electronics (ISNE) - Zhengzhou, China (2019.10.9-2019.10.10)] 2019 8th International Symposium on Next Generation Electronics (ISNE) - Equivalent Circuit Models for Next Generation Photovoltaic Devices with S-shaped I-V Curves
摘要： Certain still un-optimized emergent photovoltaic devices that are being developed for next generation solar cell applications exhibit under illumination an unwanted S-shaped concave kink in their current-voltage characteristics that substantially hinders the photovoltaic device’s energy conversion efficiency. This anomalous behavior shows up in the I-V curves of several kinds of solar cells, such as some organic cells and various other types of still evolving devices, which are promising potential candidates for future photovoltaic applications. The underlying physical phenomena responsible for the detrimental S-shaped kink can be conveniently modeled using lumped-parameter equivalent circuits that adequately replicate the illuminated S-shaped I-V characteristics. We review and discuss here the most prominent types of those equivalent circuit model configurations.
关键词： equivalent circuit model,next-generation photovoltaic devices,S-shaped kink,solar cells,organic solar cells
更新于2025-09-16 10:30:52
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Coyote optimization algorithm for the parameter extraction of photovoltaic cells
摘要： In this paper, a new and powerful metaheuristic optimization technique known as the Coyote Optimization Algorithm (COA) is proposed for the parameter extraction of the PV cell/module. It is utilized to identify the parameters of the single diode and two-diode models. Inspired by the social norms adopted by the coyotes to ensure the survivability of their species, the COA possesses several outstanding merits such as low number of control parameters, ease of implementation and diverse mechanisms for balancing exploration and exploitation. For physically meaningful solutions, a set of parametric constraints is introduced to prevent the coyotes from straying outside of the predefined boundaries of the search space. Extensive tests indicate that the proposed optimizer exhibits superior accuracy compared to other state-of-the-art EA-based parameter extraction methods. It achieved root-mean-square error (RSME) as low as 7.7301E-04 A and 7.3265E-04 A, for the single-diode and two-diode models, respectively. Moreover, the algorithm maintains outstanding performance when tested on an assortment of modules of different technologies (i.e. mono-crystalline, poly-crystalline, and thin film) at varying irradiance and temperature. The standard deviations (STDs) of the fitness values over 35 runs are measured to be less than 1 × 10?5 for both models. This suggests that the results produced by the algorithm are highly consistent. With these outstanding merits, the COA is envisaged to be a competitive option for the parameter extraction problem of PV cell/module.
关键词： Equivalent circuit model,Solar photovoltaic,Evolutionary algorithm,Coyote optimization algorithm,Parameter extraction
更新于2025-09-16 10:30:52
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Propose a MPPT Algorithm Based on Thevenin Equivalent Circuit for Improving Photovoltaic System Operation
摘要： Smart grids are considered as key solutions to solve current power security issues. Among these suggestions, microgrid is proposed to integrate distributed generations (DGs) such as photovoltaic (PV) system into the network and the control of DGs output power is getting more attention. The output power of PV arrays with nonlinear characteristics is affected by temperature, solar irradiation and load. Various maximum power point tracking (MPPT) methods for photovoltaic (PV) power systems have been considered and developed to maximize the delivered possible power. In this paper, a modelized photovoltaic source is introduced, based on the Thevenin equivalent circuit. An ordinarily employed solar system model is linearized into simple Thevenin source-resistance representation. Next, a control algorithm associated with the relationship between controller’s PWM duty cycle of the MPPT boost converter and solar array output power, namely proposed MPPT algorithm, is introduced. This proposed method is compared with an existing popular MPPT algorithm to confirm its superior performance by using the MATLAB/SIMULINK? simulation. The results show an improvement in the power generation from a PV array in any weather condition, and also help to reduce the impact of rapid change of solar irradiation on the output power variation within the time duration of change. Therefore, the proposed algorithm reduces the effect on grid frequency and motivate the PV generation penetration into the microgrids. Finally, a 50W DC-DC boost converter prototype is implemented and tested to verify the feasibility of the proposed control scheme.
关键词： photovoltaic (PV),renewable energy source,perturbation and observation method (P&O),thevenin equivalent circuit,maximum power point tracking (MPPT)
更新于2025-09-16 10:30:52
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Modeling and Readout of Quantum Dots Photodetector
摘要： In this article, an equivalent modeling approach of quantum dots (QDs) photodetector is proposed and simple model has been constructed. Experimental results show that the simulation curves and parameters agree very well with the test results. This equivalent circuit model can be simulated using the Specter tool of Cadence platform as a signal source for readout circuit design. In order to explore its higher sensitive application, readout circuits are designed to detect the weak photocurrent and turn to voltage response. In addition, a high sensitivity mico-spectrometer based on the QDs photodetector array has been designed. Based on the QDs micro-spectrometer and Olympus microscope, the skin transmittance spectra of rat have been studied.
关键词： Equivalent circuit model,micro-spectrometer,readout circuit
更新于2025-09-12 10:27:22
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Equivalent Circuit of Quantum-Dot LED and Acquisition of Carrier Lifetime in Active Layer
摘要： We propose an equivalent circuit for a quantum-dot LED (QLED), where the resistances and the capacitances are expressed in terms of the physical parameters of the QLED. The validity of the equivalent circuit is verified by measurement results. From the measured frequency response of the QLED and the calculated frequency response of the equivalent circuit, we are able to deduce the carrier lifetime in the active layer of the QLED. The availability of the equivalent circuit can facilitate the analysis of the electrical characteristics of QLEDs.
关键词： Quantum-dot light-emitting diode,frequency response,carrier lifetime,equivalent circuit
更新于2025-09-12 10:27:22
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Fundamental Aspects Concerning the Validity of the Standard Equivalent Circuit for Large‐Area Silicon Solar Cells
摘要： The standard equivalent circuit of a solar cell amounts to a lumped description by separate diode and resistor elements. Since its application to a large-area silicon solar cell effectively implies averaging the emitter resistance which, however, is closely coupled to the p–n junction, it is not self-evident that it works more or less well. Using an analytically solvable distributed series resistance model and systematically treating the deviations from the ideal case of zero emitter resistance, the equivalent circuit is found in linear order in the sheet resistivity. In this linear order, the lumped voltage losses are fully compatible with the integrated Joule losses; this compatibility turns out to be a necessary and sufficient condition for modeling the local series resistance of a large-area silicon solar cell. In higher orders of the sheet resistivity, however, the lumped voltage losses are not compatible with the integrated Joule losses, which means that the equivalent circuit cannot describe these higher orders. The equivalent circuit resulting from the linear-order lumped series resistance accounts for the experimentally observed variation of the lumped series resistance along the current–voltage characteristic, which turns out to be fully described by a dependence on the dark diode current only.
关键词： Joule losses,equivalent circuit,solar cell modeling,voltage losses,local series resistance
更新于2025-09-12 10:27:22
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Afterglow Effects as a Tool to Screen Emissive Non-Geminate Charge Recombination Processes in Organic Photovoltaic Composites
摘要： Disentangling temporally-overlapping charge carrier recombination events in organic bulk heterojunctions by optical spectroscopy is challenging. Here, a new methodology for employing delayed luminescence spectroscopy is presented. The proposed method is capable of distinguishing between recombination of spatially-separated charge carriers and trap-assisted charge recombination simply by monitoring the delayed luminescence (afterglow) of bulk heterojunctions with a quasi time-integrated detection scheme. Applied on the model composite of the donor poly(6,12-dihydro-6,6,12,12-tetraoctyl-indeno[1,2-b]fluorene-alt-benzothiadiazole) (PIF8BT) polymer and the acceptor ethyl-propyl perylene diimide (PDI) derivative, i.e. PIF8BT:PDI, the luminescence of charge-transfer (CT) states created by non-geminate charge recombination on the ns – μs time scale is observed. Fluence-dependent, quasi time-integrated detection of the CT luminescence monitors exclusively emissive charge recombination events, while rejecting the contribution of other early-time emissive processes. Trap-assisted and bimolecular charge recombination channels are identified based on their distinct dependence on fluence. The importance of the two recombination channels is correlated with the layer’s order and electrical properties of the corresponding devices. Four different microstructures of the PIF8BT:PDI composite obtained by thermal annealing are investigated. Thermal annealing of PIF8BT:PDI shrinks the PDI domains in parallel with the growth of the PIF8BT domains in the blend. Common to all states studied, the delayed CT luminescence signal is dominated by trap-assisted recombination. Yet, the minor fraction of fully-separated charge recombination in the overall CT emission increases as the difference in the size of the donor and acceptor domains in the PIF8BT:PDI blend becomes larger. Electric field-induced quenching measurements on complete PIF8BT:PDI devices confirm quantitatively the dominance of emissive trap-limited charge recombination and demonstrate that only 40% of the PIF8BT/PDI CT luminescence comes from the recombination of fully-separated charges, taking place within 200 ns after photoexcitation. The method is applicable to other non-fullerene acceptor blends beyond the system discussed here, if their CT state luminescence can be monitored.
关键词： multiple-diode equivalent circuit,fill factor,solar cell,charge trapping,perylene diimides,non-fullerene acceptors,delayed luminescence,photodetector
更新于2025-09-12 10:27:22
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Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells
摘要： The electrical properties such as interface energy barriers, defect energy levels, and densities dictate the performance of thin film solar cells. Here, we show that these properties can be quantified in cadmium telluride (CdTe) thin‐film solar cells using admittance spectroscopy‐based techniques. Our results reveal that the electrical properties in CdTe thin‐film solar cells depend on both buffer material and the fabrication atmosphere. We find that only a negligible front contact barrier exists at the CdS/CdTe front junction regardless of the fabrication atmospheres, while an obvious front barriers are observed at the ZnMgO (ZMO)/CdTe junctions. Both CdS/CdTe and ZMO/CdTe solar cells exhibit back contact barrier. The energy level of defects is shallower in CdS/CdTe cells than in ZMO/CdTe cells. The fabrication atmosphere influences the electrical properties, i.e., an oxygen‐free atmosphere reduces the front and back barrier heights and lowers the energy level of defects. The results provide critical insights for understanding and optimizing the performance of CdTe thin‐film solar cells.
关键词： admittance spectroscopy,interface barriers,cadmium telluride,equivalent circuit,photovoltaic cells
更新于2025-09-11 14:15:04
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Defected waveguide structure designs and characteristics
摘要： This article presented defected waveguide structure (DWS) designs and characteristics with microstrip-fed circular monopole antenna for ultrawideband applications. Typically, waveguide is often designed and employed as antenna and filter application in its rigid dimension. The reconfigurable design toward the waveguide in terms of structural alteration with DWS was found less concerned among researchers although defected ground structure and defected microstrip structure have been applied widely. The motivation of this article was to propose the different DWS designs and characteristics in terms of the S-parameters result. DWS in basic square geometry with different configurations of straight lines were introduced and compared with FR4 substrate waveguide. Simulated S-parameters results were modeled in terms of equivalent circuit and measured for validation. For practical measurement, waveguide ports at both open-ended surface of waveguide were replaced by the monopole antenna. For the modeled S-parameters results, the square DWS design and square DWS with horizontal straight lines showed quite similar characteristics with higher S11 and lower S21 above frequency 9 GHz. Whereas square DWS with vertical straight lines and square DWS with both horizontal vertical straight lines showed higher S11 and lower S21 below frequency 3.5 GHz. Square DWS with vertical straight lines achieved the lowest S21 around ?70 dB below 3.5 GHz and lower S21 around ?50 dB at frequency 10.3 GHz. Thus, DWS is proposed for the future smart antenna technology as it can be further modified to meet the different requirements without changing the antenna configuration.
关键词： characteristics,monopole antenna,reconfigurable,equivalent circuit modeled,defected waveguide structure
更新于2025-09-11 14:15:04