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PVRD-FASP: A Unified Solver for Modeling Carrier and Defect Transport in Photovoltaic Devices
摘要： In this article, we present a simulator for modeling transport of charge carriers and electrically active defect centers in solar cells by treating them on an equal footing, which allows us to address metastability and reliability issues. The exact nonlinear differential equations set solved by our solver is presented. The formulation of such differential equations, namely the continuity equations, drift-diffusion equation, and Poisson equation, for studying charge and defect transport is explained. The parameters needed for forming the differential equations are taken from first principle calculations. The solver is verified with test cases built on PN heterojunctions, Cu diffusion in single crystal CdTe and comparing Silvaco simulations with our numerical results.
关键词： drift-diffusion,PN heterojunction,transient solutions for continuity equation,Defect reaction solver,implicit Euler with Newton iteration,chemical reactions
更新于2025-09-16 10:30:52
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Laser switching contrast microscopy to monitor free and restricted diffusion inside the cell nucleus
摘要： A novel microscopic technique termed laser switching contrast microscopy (LSCM) allows for the imaging of the dynamics of optically switchable proteins in single cell compartments. We present an application for the monitoring of diffusive properties of single molecules of the photo-switchable fluorescent protein Dreiklang (DRK). LSCM in the cell nucleus of Chinese hamster ovary (CHO) cells cytoplasmically expressing DRK unravels quick diffusive equilibration of the DRK molecules inside the whole cytoplasm and inside the cell nucleus within seconds. The nuclear membrane is also highly permeable for DRK. Inside the nucleus entirely distinct regions are found that only partially enable diffusive protein redistribution with mean square displacement proportional to time while in other regions the mobility of the proteins seems to be restricted. After photo-switching string like patterns of light DRK molecules are observed in the cell nucleus. In addition a fraction of these DRK molecules appears immobile. The findings support recent theories of the cell interior described as a random obstacle model with an additional immobile fraction of DRK. Numerical simulations show that at different illumination intensity and different distance from the laser focus similar patterns for fluorescence recovery might be obtained in spite of strongly varying diffusion constants.
关键词： random walk,Fluorescence microscopy,diffusion constant,nanofluidics,Dreiklang,superresolution microscopy,fluorescent protein,photo-switchable molecules
更新于2025-09-16 10:30:52
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Degradation prediction of a γ-ray radiation dosimeter using InGaP solar cells in a primary containment vessel of the Fukushima Daiichi Nuclear Power Station
摘要： Indium gallium phosphide (InGaP) solar cell with a superior high-radiation resistance is expected to be a powerful candidate for a dosimeter under a high-radiation dose rate environment. In this study, in order to predict the lifetime as the dosimeter using the InGaP solar cell, we clarify the effect of minority-carrier diffusion length (L) on a radiation-induced current as a dose signal in the InGaP solar cell by irradiation tests and empirical calculations. In the irradiation tests, the short-circuit current density (Jsc) as a function of the γ-ray dose rate is measured to estimate the L for the InGaP solar cell by irradiation tests. The operational lifetime as a detector using the InGaP solar cell under various dose rates is estimated by using the empirical calculations based on the relation between the L and absorbed dose. The results suggest that the dosimeter using InGaP solar cell is able to be used during more than 10 h in the primary containment vessel of the Fukushima Daiichi Nuclear Power Plant and it has a high potential of being a radiation-resistant dosimeter that would contribute to the decommissioning.
关键词： solar cell,operation lifetime,decommissioning,radiation-induced current,minority-carrier diffusion length,Dosimetry,InGaP compound semiconductor,degradation prediction
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - New Insights on Quantum Random Number Generation (QRNG) by Phase Diffusion
摘要： We present a parametric study of QRNG harnessing phase diffusion in gain-switched DFB laser diode. Our ?ndings give new insights into the process, its limitations regarding maximum raw data rate, and advantage of pulsed regime. ? 2019 The Author(s)
关键词： quantum random number generation,pulsed regime,phase diffusion,DFB laser diode
更新于2025-09-16 10:30:52
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Impact of pre-fabrication treatments on n-type UMG wafers for 21% efficient silicon heterojunction solar cells
摘要： Silicon heterojunction solar cells achieve high conversion efficiency due to the excellent surface passivation provided by the hydrogenated intrinsic amorphous silicon films. However, they require a high-quality wafer as a starting material because their low-temperature processing does not allow for gettering. Czochralski-grown upgraded metallurgical-grade (UMG-Cz) silicon is a low-cost alternative to electronic-grade silicon for silicon solar cells, but is often limited in lifetime by grown-in defects. We have previously shown that pre-fabrication treatments, namely tabula rasa, phosphorus diffusion gettering, and hydrogenation, can significantly improve the bulk quality of UMG-Cz wafers. These help to mitigate the impact of grown-in oxygen precipitate nuclei and metallic impurities. In this work, we fabricate rear-junction silicon heterojunction solar cells on both as-grown and pre-treated UMG-Cz and electronic-grade wafers. We show that pre-fabrication treatments have a marked impact on solar cell efficiencies. With pre-fabrication treatment, the efficiency improves from 18.0% to 21.2% for the UMG-Cz cells and 21.2%–22.7% for the electronic-grade cells. Comparison of the open-circuit voltages of the as-grown and pre-treated UMG-Cz and electronic-grade cells using Quokka simulations reveals that the bulk lifetime remains the primary limiting factor for the UMG-Cz wafers.
关键词： Hydrogenation,Phosphorus diffusion gettering,Czochralski silicon,Solar-grade silicon,Tabula rasa,Silicon heterojunction solar cells
更新于2025-09-16 10:30:52
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Laser-Generated Ag Nanoparticles in Mesoporous TiO2 Films: Formation Processes and Modeling-Based Size Prediction.
摘要： Controlling the formation of nanoparticles (NPs) by direct laser writing ensures an efficient way of engineering the optical responses of nanocomposite materials through adjusting laser parameters such as power, focusing and writing speed. The process of NP’s growth, photo-oxidation, and reduction affect the light absorption by an ensemble of laser-activated NPs. However, those self-consistent processes are not well understood. Previous studies explained the growth or shrinkage of silver NPs by neglecting heat diffusion. It remained unclear, however, how the NP size can be controlled by the laser writing speed. In this work, based on the coupled calculations of size-variation, light absorption, and heat diffusion by an emsemble of NPs, we propose a two-dimensional model taking account of spatial information of size and temperature to have a further investigation into the process. The spatial size distribution is revealed to be non-uniform leading to the transmission inhomogeneity along the laser written lines. This fact is confirmed by the in-situ transmission experiments. The performed study also depicts a novel view in which NPs grow ahead of the laser beam center due to the heat diffusion. The nonlinear growth never stops until it exhausts the majority of the free Ag0 in the matrix, while the amount of Ag0 by reduction cannot compensates the consumption. After that, the photo-oxidation dominates the process and finally acts as the controlling role in NP size depending on the writing speed. The simulations also show that it is not the activation energy of Ag0 diffusion but the ionization efficiency affect the final NP size, which helps understand in how to improve the laser processing of differently prepared samples.
关键词： photo-oxidation,silver nanoparticles,nanoparticles,TiO2 films,laser writing,heat diffusion
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Gettering efficacy of an APCVD glasses based stacked co-diffusion for bifacial mc-Si PERT solar cells
摘要： Gettering of impurities is an important task in p-type mc-Si solar cell production. Phosphorus diffusion via POCl3 is currently the most common way to achieve this. We report about the gettering efficacy of a co-diffusion in which POCl3 is not used. Phosphorus and boron containing glasses are both deposited prior to the diffusion via atmospheric pressure chemical vapor deposition (APCVD). The presented APCVD glasses based co-diffusion allows a loading without spacing and therefore has the potential for a very high throughput. As we demonstrate in this work, the overall gettering efficacy in different kinds of stacks is similar to the gettering efficacy in non-stacked APCVD glasses based diffusions. The reduction of interstitial iron in the analyzed lifetime samples is ascribed to phosphorus diffusion gettering and works in stacks just as well.
关键词： co-diffusion,Gettering,PERT solar cells,APCVD,mc-Si
更新于2025-09-16 10:30:52
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Enhancing electron diffusion length in narrow-bandgap perovskites for efficient monolithic perovskite tandem solar cells
摘要： Developing multijunction perovskite solar cells (PSCs) is an attractive route to boost PSC efficiencies to above the single-junction Shockley-Queisser limit. However, commonly used tin-based narrow-bandgap perovskites have shorter carrier diffusion lengths and lower absorption coefficient than lead-based perovskites, limiting the efficiency of perovskite-perovskite tandem solar cells. In this work, we discover that the charge collection efficiency in tin-based PSCs is limited by a short diffusion length of electrons. Adding 0.03 molar percent of cadmium ions into tin-perovskite precursors reduce the background free hole concentration and electron trap density, yielding a long electron diffusion length of 2.72 ± 0.15 μm. It increases the optimized thickness of narrow-bandgap perovskite films to 1000 nm, yielding exceptional stabilized efficiencies of 20.2 and 22.7% for single junction narrow-bandgap PSCs and monolithic perovskite-perovskite tandem cells, respectively. This work provides a promising method to enhance the optoelectronic properties of narrow-bandgap perovskites and unleash the potential of perovskite-perovskite tandem solar cells.
关键词： narrow-bandgap perovskites,perovskite solar cells,tandem solar cells,electron diffusion length,cadmium ions
更新于2025-09-16 10:30:52
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Theoretical Study of Proton Radiation Influence on the Performance of a Polycrystalline Silicon Solar Cell
摘要： The aim of this work is to study the behaviour of a silicon solar cell under the irradiation of di?erent ?uences of high-energy proton radiation (10 MeV) and under constant multispectral illumination. Many theoretical et experimental studies of the e?ect of irradiation (proton, gamma, electron, etc.) on solar cells have been carried out. These studies point out the e?ect of irradiation on the behaviour of the solar cell electrical parameters but do not explain the causes of these e?ects. In our study, we explain fundamentally the causes of the e?ects of the irradiation on the solar cells. Taking into account the empirical formula of di?usion length under the e?ect of high-energy particle irradiation, we established new expressions of continuity equation, photocurrent density, photovoltage, and dynamic junction velocity. Based on these equations, we studied the behaviour of some electronic and electrical parameters under proton radiation. Theoretical results showed that the defects created by the irradiation change the carrier distribution and the carrier dynamic in the bulk of the base and then in?uence the solar cell electrical parameters (short-circuit current, open-circuit voltage, conversion e?ciency). It appears also in this study that, at low ?uence, junction dynamic velocity decreases due to the presence of tunnel defects. Obtained results could lead to improve the quality of the junction of a silicon solar cell.
关键词： silicon solar cell,proton radiation,diffusion length,electrical parameters,carrier distribution,junction dynamic velocity
更新于2025-09-16 10:30:52
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Comparison thermochemical and thermophysical performances analysis in laser processing by dynamic heat-matter diffusion coupling simulation and corresponding experiment validation
摘要： The laser-matter interaction contains complex thermophysical and thermochemical responses. The variation of energy and composition happen in thermophysical and thermochemical process will totally change the interaction behaviors. In order to obtain an accurate mechanism and promote the understanding of laser-matter interaction, all thermophysical and thermochemical responses, especially the thermochemical part, should be considered and investigated. In this study, a coupled heat-matter diffusion model based on thermodynamic chemical equilibrium finite-element method and thermochemical ablation theory was established. The materials with complex reaction enthalpy change in high temperature environment were chosen to validate the model. The results show that this model is accurate, as the maximum error of back-surface temperature response is just 4.0% between experimental and calculation values. The detailed variations of composition, temperature and optical reflection were obtained and analyzed, which is in good agreement with the experiment. This coupled heat-matter diffusion model including all thermophysical and thermochemical response has the great potential in nearly all laser-matter interaction involved application.
关键词： Coupled heat-matter diffusion method,Laser ablation,Graphite/SiO2 composite,Carbothermic reaction,Finite-element
更新于2025-09-16 10:30:52