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Uniform-in-time bounds for approximate solutions of the drift–diffusion system
摘要： In this paper, we consider a numerical approximation of the Van Roosbroeck’s drift–diffusion system given by a backward Euler in time and finite volume in space discretization, with Scharfetter–Gummel fluxes. We first propose a proof of existence of a solution to the scheme which does not require any assumption on the time step. The result relies on the application of a topological degree argument which is based on the positivity and on uniform-in-time upper bounds of the approximate densities. Secondly, we establish uniform-in-time lower bounds satisfied by the approximate densities. These uniform-in-time upper and lower bounds ensure the exponential decay of the scheme towards the thermal equilibrium as shown in Bessemoulin-Chatard (Numer Math 25(3):147–168, 2016).
关键词： Finite volume method,Uniform-in-time bounds,Scharfetter–Gummel scheme,Drift–diffusion system,Numerical analysis
更新于2025-09-23 15:23:52
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Parallel domain decomposition methods for a quantum-corrected drift–diffusion model for MOSFET devices
摘要： In this paper, we describe parallel domain decomposition methods based on the restricted additive Schwarz (RAS) method for a quantum-corrected drift-diffusion (QCDD) model for MOSFET devices. We have developed hybrid Message Passing Interface (MPI)/OpenMP parallelization algorithms of the QCDD system. For internode parallelization, two extensions of the RAS method are newly developed for the QCDD model. For intranode parallelization, we combine the conjugate gradient (CG) and BiCGSTAB procedures with a splitting-up operator method to realize parallelization of the incomplete factorization. The parallel numerical results for a three-dimensional Si bulk n-MOSFET on a multi-core NEC SX-ACE parallel computer are demonstrated. The intranode parallel numerical results are further evaluated on a many-core Cray XC40 parallel computer.
关键词： Restricted additive Schwarz method,Domain decomposition method,Numerical methods,Device simulation,Semiconductor,quantum-corrected drift–diffusion model
更新于2025-09-23 15:21:21
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Coupled 3D master equation and 1D drifta??diffusion approach for advanced OLED modeling
摘要： A novel simulation approach for excitonic organic light-emitting diodes (OLEDs) is established by combining a continuous one-dimensional (1D) drift-diffusion (DD) model for the charge carrier dynamics with a three-dimensional (3D) master equation (ME) model describing the exciton dynamics in a multi-layer OLED stack with an additional coupling to a thin-film optics solver. This approach effectively combines the computational efficiency of the 1D DD solver with the physical accuracy of a discrete 3D ME model, where excitonic long-range interactions for energy transfer can be taken into account. The coupling is established through different possible charge recombination types as well as the carrier densities themselves. We show that such a hybrid approach can efficiently and accurately describe steady-state and transient behavior of optoelectronic devices reported in literature. Such a tool will facilitate the optimization and characterization of multilayer OLEDs and other organic semiconductor devices.
关键词： drift-diffusion,excitons,master equation,OLED
更新于2025-09-23 15:21:01
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Two different types of S-shaped J-V characteristics in organic solar cells
摘要： In this paper, S-shaped characteristics of organic solar cells (OSCs) are analyzed by a drift–diffusion model which includes charge carrier surface recombination and thermal injection on the anode and cathode through boundary conditions. By varying surface recombination velocities (SRVs) for electrons and holes on both contacts and the injection barrier heights for majority carriers, two different S-shaped deviations in OSCs J-V characteristics were observed. The first type of S-shaped J-V characteristic manifests the S-shape bending in the vicinity of the voltage axis, after which it rises almost exponentially. This kind of S-shape deformation was found to arise from the finite SRVs. The second type of the S-shaped J-V characteristic also makes a kink near the voltage axis but proceeds to grow monotonically, having only one saddle point. The S-shaped J-V curve of this kind turned out to be the consequence of the electron injection barrier height larger than 0.2 eV. The validity of our model is confirmed by comparing the simulated J-V curves with the experimentally obtained data. The model has been applied to the ITO/PEDOT:PSS/P3HT:PCBM/Al and ITO/PEDOT:PSS/P3HT:ICBA/Al solar cells. For the P3HT:PCBM based solar cells, the regular J-shaped J-V curves were measured, while for the P3HT:ICBA solar cells, the J-V curves with anomalous S-shape behavior were recorded. All experimentally obtained J-V curves were reproduced very well with our model. It seems that the ITO/PEDOT:PSS/ P3HT:ICBA/Al solar cell S-shaped J-V curve originates from the electron barrier height on the cathode contact, rather than from the low surface recombination on the electrodes.
关键词： Solar cells,Drift–diffusion model,Organic materials,S-shaped J-V curve
更新于2025-09-19 17:13:59
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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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Three-Dimensional Drift-Diffusion Model for Simulation and Investigation of Bordering Effects in Silicon Solar Cells
摘要： In this paper, the influence of bordering effects on solar cells parameters is investigated through a three-dimensional model, which these effects are ignored in one dimensional model cases. They are incorporated in two and three-dimensional models by an additional recombination term in the drift-diffusion equations. The additional recombination term is calculated via the Schockley-Red-Hall theory. The model includes also radiative recombination process and neglects auger recombination (considered only in heavily doped p-n junctions). This model is based on the solution of Poisson’s equation and continuity equations of electrons and holes. At metallic contacts, Dirichlet-type boundary conditions are applied, while Neumann-type boundary conditions are used in other interfaces of the device. This modified model was tested on a simple Silicon p-n junction to show the contribution of the bordering effects in the carrier and currents densities.
关键词： Shockley-Read-Hall,p-n junction,3D model simulation,Solar cells,Bordering effects,Drift-diffusion model,Boundary conditions
更新于2025-09-16 10:30:52
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The improved performance of BHJ organic solar cells by random dispersed metal nanoparticles through the active layer
摘要： In this paper, the performance of bulk heterojunction (BHJ) organic solar cells (OSCs) in the presence of random dispersed Ag nanoparticles (NPs) into the active layer is investigated. By the well-known Maxwell-Garnett effective medium theory, we have analyzed the optical absorption of P3HT:PCBM and PCDTBT:PCBM photoactive blends when spherical Ag NPs are randomly embedded in them. The photocurrent enhancement of OSCs based on the blend:AgNP composites has been examined by an analytical drift-diffusion method. Our theoretical analysis demonstrates a considerable enhancement in the optical absorption of the blends with Ag NPs resulted in the power conversion efficiency (PCE) improvement of the devices up to 65.6% in comparison with the reference blends. In addition, the spectrally correlation of simulated external quantum efficiency (EQE) and the absorption coefficient enhancements proves the influence of localized surface plasmon resonance (LSPR) of the Ag NPs in boosting the performance of the OSC devices.
关键词： plasmonic enhancement,drift-diffusion model,Organic solar cells,effective medium theory,Random distribution
更新于2025-09-16 10:30:52
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Optimization of MAPbI$_3$-Based Perovskite Solar Cell With Textured Surface
摘要： In this article, the optimized condition for a perovskite solar cell (PSC) with textured surface has been calculated. To accurately model the transport in organic material and organic/inorganic interface, the Gaussian-like density of state function was utilized into Poisson and drift-diffusion solver to present the tail states in the organic material. To calibrate the simulation model, the planar structures with published experimental results are compared. Our results show that the textured structure can improve the open-circuit voltage (Voc) and fill factor and overcome the major problem of PSC because of the short diffusion length. Finally, the efficiency has been improved from 17.8% (planar) to 20.8% (textured). If the metal contact with a suitable work function is chosen, it can be further improved to 22.9%.
关键词： perovskite solar cell (PSC),organic material,MAPbI3,Poisson equation,Drift-diffusion equation,2-D finite-difference time domain (FD-TD),tail states model
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Udine, Italy (2019.9.4-2019.9.6)] 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Hybrid Method For Electromagnetic Modelling of Coherent Radiation in Semiconductor Lasers
摘要： In this paper hybrid method for electromagnetic (EM) modelling of coherent radiation in semiconductor lasers is presented. Described approach consist of drift diffusion (DD) model and electromagnetic simulation. Four-level two-electron atomic system with Pauli Exclusion Principle (PEP) extended by electric pumping ratio has been used as lasing model.
关键词： ADE,drift diffusion,PEP,device,FDTD,simulation,nonlinear optics
更新于2025-09-12 10:27:22
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Using Deep Machine Learning to Understand the Physical Performance Bottlenecks in Novel Thin‐Film Solar Cells
摘要： There is currently a worldwide effort to develop materials for solar energy harvesting which are efficient and cost effective, and do not emit significant levels of CO2 during manufacture. When a researcher fabricates a novel device from a novel material system, it often takes many weeks of experimental effort and data analysis to understand why any given device/material combination produces an efficient or poorly optimized cell. It therefore takes the community tens of years to transform a promising material system to a fully optimized cell ready for production (perovskites are a contemporary example). Herein, developed is a new and rapid approach to understanding device/material performance, which uses a combination of machine learning, device modeling, and experiment. Providing a set of electrical device parameters (charge carrier mobilities, recombination rates, trap densities, etc.) in a matter of seconds thus offers a fast way to directly link fabrication conditions to device/material performance, pointing a way to further and more rapid optimization of light harvesting devices. The method is demonstrated by using it to understand annealing temperature and surfactant choice and in terms of charge carrier dynamics in organic solar cells made from the P3HT:PCBM, PBTZT-stat-BDTT-8:PCBM, and PTB7:PCBM material systems.
关键词： charge carrier mobility,machine learning,organic solar cells,thin film solar cells,drift diffusion
更新于2025-09-12 10:27:22