Performance Improvement of CIGS Solar Cell: A Simulation Approach by SCAPS-1D

Thin-film solar cells possess the distinct advantage of being cost-effective and relatively simple to manufacture. Nevertheless, it is of utmost importance to enhance their overall performance. In this research work, copper indium gallium selenide (CIGS)-based ultra-thin solar cell (SC) configuration (Ag/ZnO/ZnSe/CIGS/Si/Ni) has been designed and examined using SCAPS-1D. The numerical calculations revealed that this new design resulted in a substantial improvement in SC performance. This study explores the utilization of two absorber layers, CIGS and Si, both with a total of 2 μm thickness, to enhance device performance while reducing material costs, observing an increase in key SC parameters as the Si absorber layer thickness is increased, reaching a maximum efficiency of 29.13% when CIGS and Si thicknesses are set at 0.4 μm and 1.6 μm, respectively with doping absorber doping density of 1014 cm-3. Furthermore, we analyze the impact of variation in absorber and buffer layer thickness, as well as doping concentration, surface recombination velocity (SRV), electron affinity, series-shunt resistance, and temperature, on optimized CIGS SC parameters such as short-circuit current density (JSC), open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE). The findings yielded by the investigation offer significant elucidation regarding the fabrication of economically viable and highly efficient non-hazardous CIGS ultra-thin SC.

On the energy conservation electrostatic particle-in-cell/Monte Carlo simulation: Benchmark and application to the radio frequency discharges

We benchmark and analyze the error of energy conservation （EC） scheme in particle-in-cell/Monte Carlo （PIC/MC） algorithms by simulating the radio frequency discharge. The plasma heating behaviors and electron distributing functions obtained by one-dimensional （1D） simulation are analyzed. Both explicit and implicit algorithms are checked. The results showed that the EC scheme can eliminated the self-heating with wide grid spacing in both cases with a small reduction of the accuracies. In typical parameters, the EC implicit scheme has higher precision than EC explicit scheme. Some ＂numerical cooling＂ behaviors are observed and analyzed. Some other errors are also analyzed. The analysis showed that the EC implicit scheme can be used to qualitative estimation of some discharge problems with much less computational resource cost without much loss of accuracies.

Implicit electrostatic particle-in-cell/Monte Carlo simulation for the magnetized plasma:Algorithms and application in gas-inductive breakdown

An implicit electrostatic particle-in-cell/Monte Carlo （PIC/MC） algorithm is developed for the magnetized discharging device simulation. The inductive driving force can be considered. The direct implicit PIC algorithm （DIPIC） and energy conservation scheme are applied together and the grid heating can be eliminated in most cases. A tensor-susceptibility Poisson equation is constructed. Its discrete form is made up by a hybrid scheme in one-dimensional （1D） and two- dimensional （2D） cylindrical systems. A semi-coarsening multigrid method is used to solve the discrete system. The algorithm is applied to simulate the cylindrical magnetized target fusion （MTF） pre-ionization process and get qualitatively correct results. The potential application of the algorithm is discussed briefly.

Electromagnetic Particle-in-Cell Simulations of Electron Holes Formed During the Electron Two-Stream Instability

Previous electrostatic particle-in-cell （PIC） simulations have pointed out that elec- tron phase-space holes （electron holes） can be formed during the nonlinear evolution of the electron two-stream instability. The parallel cuts of the parallel and perpendicular electric field have bipolar and unipolar structures in these electron holes, respectively. In this study, two-dimensional （2D） electromagnetic PIC simulations are performed in the x - y plane to investigate the evolution of the electron two-stream instability, with the emphasis on the magnetic structures associated with these electron holes in different plasma conditions. In the simulations, the background magnetic field （Bo = Boer） is along the x direction. In weakly magnetized plasma （Ωe 〈ωpe, where Ωe and ωpe are the electron gyrofrequency and electron plasma frequency, respectively）, several 2D electron holes are formed. In these 2D electron holes, the parallel cut of the fluctuating magnetic field δBx and δBz has unipolar structures, while the fluctuating magnetic field δBy has bipolar structures. In strongly magnetized plasma （Ωe 〉 ωpe）, several quasi-lD electron holes are formed. The electrostatic whistler waves with streaked structures of Ey are excited. The fluctuating mag- netic field δBx and δBz also have streaked structures. The fluctuating magnetic field δBx and δBy are produced by the current in the z direction due to the electric field drift of the trapped elec- trons, while the fluctuating magnetic field δBz can be explained by the Lorentz transformation of a moving quasielectrostatic structure. The influences of the initial temperature anisotropy on the magnetic structures of the electron holes are also analyzed. The electromagnetic whistler waves are found to be excited in weakly magnetized plasma. However, they do not have any significant effects on the electrostatic structures of the electron holes.

Particle-in-cell simulation for effect of anode temperature on discharge characteristics of a Hall effect thruster

Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters （HETs）. In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency.

Effects of electron trapping on nonlinear electron-acoustic waves excited by an electron beam via particle-in-cell simulations

By performing one-dimensional particle-in-cell simulations,the nonlinear effects of electronacoustic(EA)waves are investigated in a multispecies plasma,whose constituents are hot electrons,cold electrons,and beam electrons with immobile neutralized positive ions.Numerical analyses have identified that EA waves with a sufficiently large amplitude tend to trap cold electrons.Because EA waves are dispersive,where the wave modes with different wavenumbers have different phase velocities,the trapping may lead to the nlixing of cold electrons.The cold electrons finally get thermalized or heated.The investigation also shows that the excited EA waves give rise to a broad range of wave frequencies,which may be helpful for understanding the broadband-electrostatic-noise spectrum in the Earth's auroral region.

Analysis of microwave propagation in a time-varying plasma slab with particle-in-cell simulations

Continuous microwave propagation through a time-varying plasma and frequency up-conversion has been demonstrated by particle-in-cell (PIC) simulation. In principle, it is possible to transform a 2.45 GHz source radiation to an arbitrary larger frequency radiation. The energy conversion is also obtained by the theoretical analysis and has been testified by PIC simulation. The source wave was propagating in a parallel plate waveguide locally filled with the ionized gas. In this paper we would discuss the effects of the rise time, the plasma length, the switching time and the collision frequency on the energy conversion, and the methods to improve the upshift wave energy are proposed. We also put forward the new concept of the critical values of the rise time and the source wave amplitude to provide a theoretical basis for the selection of parameters in the experiments.

Particle-in-cell/Monte Carlo simulation of filamentary barrier discharges

The plasma behavior of filamentary barrier discharges in helium is simulated using a twodimensional（2D） particle-in-cell/Monte Carlo model. Four different phases have been suggested in terms of the development of the discharge： the Townsend phase; the space-charge dominated phase; the formation of the cathode layer, and the extinguishing phase. The spatialtemporal evolution of the particle densities, velocities of the charged particles, electric fields, and surface charges has been demonstrated. Our simulation provides insights into the underlying mechanism of the discharge and explains many dynamical behaviors of dielectric barrier discharge（DBD） filaments.

COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE ELEMENT METHOD

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

Device simulation of lead-free CH_3NH_3SnI_3 perovskite solar cells with high efficiency

The lead-free perovskite solar cells(PSCs) have drawn a great deal of research interest due to the Pb toxicity of the lead halide perovskite.CHNHSnIis a viable alternative to CHNHPbX,because it has a narrower band gap of 1.3 eV and a wider visible absorption spectrum than the lead halide perovskite.The progress of fabricating tin iodide PSCs with good stability has stimulated the studies of these CHNHSnIbased cells greatly.In the paper,we study the influences of various parameters on the solar cell performance through theoretical analysis and device simulation.It is found in the simulation that the solar cell performance can be improved to some extent by adjusting the doping concentration of the perovskite absorption layer and the electron affinity of the buffer and HTM,while the reduction of the defect density of the perovskite absorption layer significantly improves the cell performance.By further optimizing the parameters of the doping concentration(1.3 × 10cm~3) and the defect density(1 × 10cm~3) of perovskite absorption layer,and the electron affinity of buffer(4.0 eV) and HTM(2.6 eV),we finally obtain some encouraging results of the Jof 31.59 mA/cm~2,Vof 0.92 V,FF of 79.99%,and PCE of 23.36%.The results show that the lead-free CHNHSnIPSC is a potential environmentally friendly solar cell with high efficiency.Improving the Snstability and reducing the defect density of CHNHSnIare key issues for the future research,which can be solved by improving the fabrication and encapsulation process of the cell.

Studies on the polycrystalline silicon/SiO2 stack as front surface field for IBC solar cells by two-dimensional simulations

Interdigitated back contact（IBC） solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrystalline silicon/SiO_2 stack structure as front surface field to passivate the front surface of IBC solar cells is proposed. The passivation quality of this structure is investigated by two dimensional simulations. Polycrystalline silicon layer and SiO_2 layer are optimized to get the best passivation quality of the IBC solar cell. Simulation results indicate that the doping level of polycrystalline silicon should be high enough to allow a very thin polycrystalline silicon layer to ensure an effective passivation and small optical losses at the same time. The thickness of SiO_2 should be neither too thin nor too thick, and the optimal thickness is 1.2 nm.Furthermore, the lateral transport properties of electrons are investigated, and the simulation results indicate that a high doping level and conductivity of polycrystalline silicon can improve the lateral transportation of electrons and then the cell performance.

Effects of simulated zero gravity on adhesion,cell structure,proliferation,and growth behavior,in glioblastoma multiforme

All life on Earth has evolved under the influence of continuous gravity,and methods have been developed to balance this influence with the biological evolution of organisms at the cellular and system levels.However,when exposed to zero gravity in space,the balance between cell structure and external forces is destroyed,resulting in changes at the cellular level(e.g.,cell morphology,adhesion,viability,apoptosis,etc.),and understanding the molecular mechanism of cell response to zero gravity will help to cope with diseases that rely on mechanical response.Therefore,biological research in space and zero gravity is a unique step in developing the best anti-cancer treatments,which is a great challenge to humanity.In this study,multicellular glioma cancer cells from a brain tumor in a 72-year-old Iraqi patient were subjected to simulated zero gravity for 24 h,and the results showed that most of the cells lost their adhesion,which is considered to be the first step toward cell apoptosis.In addition to the formation of multicellular spheroids,the results also showed that the inhibition rate for cell death was 32%in comparison to the control cells.Moreover,the cells showed a clear change in their cellular morphology and growth behavior.These results give new hope for fighting cancer distinctively,and such a treatment method has no side effects in comparison to traditional chemical and radiological ones.

Numerical simulation of a triple-junction thin-film solar cell based on μc-Si_(1-x)Ge_x :H

In this paper, a-Si：H/a-SiGe：H/μc-SiGe：H triple-junction solar cell structure is proposed. By the analyses of mi- croelectronic and photonic structures （AMPS-1D） and our TRJ-F/TRJ-M/TRJ-B tunneling-recombination junction （TRJ） model, the most preferably combined bandgap for this structure is found to be 1.85 eV/1.50 eV/1.0 eV. Using more realistic material properties, optimized thickness combination is investigated. Along this direction, a-Si：H/a-SiGe：H/μc-SiGe：H triple cell with an initial efficiency of 12.09% （Voc = 2.03 V, FF = 0.69, Jsc = 8.63 mA/cm^2, area = 1 cm^2） is achieved in our laboratory.

Optical simulation of CsPbI_(3)/TOPCon tandem solar cells with advanced light management

Monolithic perovskite/Si tandem solar cells(TSCs)have experienced rapid development in recent years,demonstrating its potential to exceed the Shockley-Queisser limit of single junction Si solar cells.Unlike typical organic-inorganic hybrid perovskite/silicon heterojunction TSCs,here we propose CsPbI_(3)/TOPCon TSC,which is a promising architecture in consideration of its pleasurable thermal stability and good compatibility with current PERC production lines.The optical performance of CsPbI_(3)/TOPCon TSCs is simulated by the combination of ray-tracing method and transfer matrix method.The light management of the CsPbI_(3)/TOPCon TSC begins with the optimization of the surface texture on Si subcell,indicating that a bifacial inverted pyramid with a small bottom angle of rear-side enables a further minimization of the optical losses.Current matching between the subcells,as well as the parasitic absorption loss from the front transparent conductive oxide,is analyzed and discussed in detail.Finally,an optimized configuration of CsPbI_(3)/TOPCon TSC with a31.78%power conversion efficiency is proposed.This work provides a practical guidance for approaching high-efficiency perovskite/Si TSCs.

Numerical Simulation of Tandem Using ZnS as a Buffer Layer Cu I(1-x) CaxSe2/CuGaSe2

In the global context of diversification of usable energy sources, the use of renewable energies, in particular solar photovoltaic energy, is becoming increasingly important. As such, the development of a new generation of photovoltaic cells based on the CIGS material is promising. Indeed, the efficiency of these cells has exceeded 20% in recent years. Thus, our work consists in the modeling of a tandem solar cell based on Cu(In,Ga)Se2 (CGS/CIGS). The goal is to optimize its physical and geometrical parameters in order to obtain a better photovoltaic conversion efficiency compared to other research works on tandem in the past. We used AMPS-1D software for the simulation. When we realize the tandem, the least efficient cell (CGS) imposes the current and the shape of the J-V characteristic of the tandem. We obtained a theoretical efficiency of 39.30% which is significantly higher than the efficiencies obtained in the past by other researchers with a short circuit current of 34.60 mA/cm2, an open circuit voltage of 1.74 V and a form factor of 65.20%. The simulation also showed that the high defect density in the material strongly impacts the performance of the tandem.

Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons（holes）in the device are collected by anode（cathode）. The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination（BR）or geminate recombination（GR） intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same.Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.

Numerical modeling and simulation of PEM fuel cells: Progress and perspective

This paper provides a comprehensive review on the research and development in multi-scale numerical modeling and simulation of PEM fuel cells. An overview of recent progress in PEM fuel cell modeling has been provided. Fundamental transport phenomena in PEM fuel cells and the corresponding mathematical formulation of macroscale models are analyzed. Various important issues in PEM fuel cell modeling and simulation are examined in detail, including fluid flow and species transport, electron and proton transport, heat transfer and thermal management, liquid water transport and water management, transient response behaviors, and cold-start processes. Key areas for further improvements have also been discussed.

Simulation design of P–I–N-type all-perovskite solar cells with high efficiency

According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers and the perovskite absorber constitute the all-perovskite cell. By modulating the cell parameters, such as layer thickness values, doping concentrations and energy bands of n-, i-, and p-type perovskite layers, the all-perovskite solar cell obtains a high power conversion efficiency of 25.84%. The band matched cell shows appreciably improved performance with widen absorption spectrum and lowered recombination rate, so weobtain a high J_（sc） of 32.47 m A/cm^2. The small series resistance of the all-perovskite solar cell also benefits the high J_（sc）. The simulation provides a novel thought of designing perovskite solar cells with simple producing process, low production cost and high efficient structure to solve the energy problem.

Dynamic self-adaptive ANP algorithm and its application to electric field simulation of aluminum reduction cell

Region partition(RP) is the key technique to the finite element parallel computing(FEPC),and its performance has a decisive influence on the entire process of analysis and computation.The performance evaluation index of RP method for the three-dimensional finite element model(FEM) has been given.By taking the electric field of aluminum reduction cell(ARC) as the research object,the performance of two classical RP methods,which are Al-NASRA and NGUYEN partition(ANP) algorithm and the multi-level partition(MLP) method,has been analyzed and compared.The comparison results indicate a sound performance of ANP algorithm,but to large-scale models,the computing time of ANP algorithm increases notably.This is because the ANP algorithm determines only one node based on the minimum weight and just adds the elements connected to the node into the sub-region during each iteration.To obtain the satisfied speed and the precision,an improved dynamic self-adaptive ANP(DSA-ANP) algorithm has been proposed.With consideration of model scale,complexity and sub-RP stage,the improved algorithm adaptively determines the number of nodes and selects those nodes with small enough weight,and then dynamically adds these connected elements.The proposed algorithm has been applied to the finite element analysis(FEA) of the electric field simulation of ARC.Compared with the traditional ANP algorithm,the computational efficiency of the proposed algorithm has been shortened approximately from 260 s to 13 s.This proves the superiority of the improved algorithm on computing time performance.

Results in Sizing and Simulation of PV Applications Based on Different Solar Cell Technologies

Modeling and simulation of photovoltaic (PV) systems represents an essential task for the integration of PV panels in current power applications. At the present time, there are sizing tools of photovoltaic systems available on the market, taking into account the proposed energy consumption, site localization and system cost. An advanced specialized program (PVSyst) was considered. The sizing and simulations of two PV important applications were developed using PV modules based on three different technologies: monocrystalline and polycrystalline silicon, as well as CIS. Our results showed how different types of solar cell technologies influenced the final power output and performances for a PV LED lighting, as well as for a PV water pumping system, in terms of overall yield, efficiency and system availability.