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Effect of Ag-doping on the structural, optical, electrical and photovoltaic properties of thermally evaporated Cadmium Selenide thin films
摘要： To study the capability of the CdSe thin films to use as an absorber layer in semi-transparent thin film solar cells, the structural, optical, electrical and photovoltaic properties of thermally evaporated CdSe thin films (thickness 300 nm) as a function of silver-doping were investigated. A novel and facile method was used to Ag-doping of the samples. Some aqueous solution of silver nitrate (with various concentration) was spin coated onto the surface of CdSe thin films followed by air-annealing to diffuse silver dopants into the layers. The field emission scanning electron microscope (FE-SEM) images showed that the surface of CdSe thin films was improved with our doping method. X-ray diffraction (XRD) analysis revealed the hexagonal structure of the samples. The crystallite size, micro-strain and dislocation density of CdSe thin films were evaluated using XRD patterns. The transmittance spectra in the wavelength range of 400–2500 nm were measured and then used to study other optical parameters. The optical energy band gap was decreased with Ag-doping from 1.96 eV to 1.67 eV. The electrical conductivity of FTO/CdSe:Ag/Al Schottky junction devices was improved by Ag-doping, and the photovoltaic efficiency was increased by Ag-doping form 1.53% for the undoped sample to 2.78% for the sample with the highest doping concentration. Obtained results show that Ag-doped CdSe thin films are a promising candidate to use as an absorber layer in semi-transparent solar cells and colorful photovoltaic windows.
关键词： semi-transparent solar cell,Ag-doping,CdSe thin films,Schottkty junction,Urbach energy,thermionic emission
更新于2025-09-16 10:30:52
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Optimal parameter identification of triple-junction photovoltaic panel based on enhanced moth search algorithm
摘要： The paper proposes an enhanced moth search algorithm (EMSA) employed in identifying the optimal parameters of Triple-Junction (TJS) photovoltaic panel under different operating conditions. Disruptor operator (DO) is placed in the moth search algorithm (MSA) to improve its performance. The DO is used to improve the diversity of the MSA and avoid it from stuck in local point. The presented fitness function in this work is the integral time absolute error (ITAE) between the triple junction PV panel experimental and calculated currents. The panel is simulated in Simulink and tested under different solar radiation conditions. Additionally, the panel performance is investigated under the shadow effect; a comparative study is performed with other metaheuristic optimization approaches and with Hammerstein and wiener identification technique. The proposed EMSA operates with efficiencies around 99.66% and 99.89%for first and second patterns respectively. It is confirmed the superiority and reliability of the proposed EMSA in extracting the optimal parameters of TJS based module operated at different operating conditions.
关键词： Moth search algorithm,Disruptor operator,Triple-junction solar cell
更新于2025-09-16 10:30:52
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Single-step growth of high quality CIGS/CdS heterojunctions using Pulsed Laser Deposition
摘要： This work reports on the utilization of pulsed laser deposition (PLD) for the preparation of CdS thin films and CdS/Cu(In,Ga)Se2 heterojunction structures on soda-lime glass (SLG) and Mo-coated SLG substrates, respectively, under various process conditions. Single phase, stoichiometric and high optical quality CdS films are obtained at a fluence of 1.1 J/cm2 and at deposition temperatures of 200 – 400oC. The results of this investigation were used to grow CdS on Cu(In,Ga)Se2/Mo/SLG. Both Cu(In,Ga)Se2 and CdS layers have been deposited sequentially using PLD without interrupting the influence of CdS deposition temperature on the properties of CdS/Cu(In,Ga)Se2 heterojunction has been extensively studied and is reported herein for the first time. Low series and high shunt resistances are obtained for the samples where CdS was grown at 200 and 300oC. The CdS/Cu(In,Ga)Se2 diode grown at CdS deposition temperature of 300oC exhibits the lowest ideality factor and leakage current, indicating the better quality of the diode. The results of this work demonstrate that high-quality CdS/Cu(In,Ga)Se2 diodes are obtained using pulsed laser deposition in a single-step growth process, eliminating the need for selenization of Cu(In,Ga)Se2 and the use of other growth techniques such as chemical bath deposition for CdS.
关键词： CdS deposition temperature,Electrical properties,Pulsed Laser Deposition,CdS,Optical properties,CdS/CIGS junction
更新于2025-09-16 10:30:52
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Flexible four-junction inverted metamorphic AlGaInP/AlGaAs/ In0.17Ga0.83As/In0.47Ga0.53As solar cell
摘要： A flexible four-junction (4 J) AlGaInP/AlGaAs/In0.17Ga0.83As/In0.47Ga0.53As solar cell with the band gap energy of 1.92/1.53/1.18/0.82eV was fabricated. Taking advantages of aluminum (Al)-contained material as well as metamorphic growth, the design of multiple junction solar cells became much easier and more flexible. In order to accommodate lattice mismatch between two InGaAs sub cells, compositionally step-graded AlGaInAs buffer layers were applied to release the mismatch strain during the inverted metamorphic (IMM) 4 J solar cells growth. A flexible 4 J solar cell on a 50 μm thick polyimide (PI) film was successfully fabricated by using temporary bonding and epitaxial layer lift-off via selective wet chemical etching. A conversion efficiency of 25.76% (AM1.5G) with an open circuit voltage of 3.46V, a short-circuit current density of 9.07 mA/cm2 and a fill factor of 82.14% was obtained without anti-reflection coating (ARC), and it would be higher than 32% by ARC integration. The mass density of the 4 J flexible solar cell was only 467 g/m2, and the specific power was up to 550 W/kg.
关键词： Flexible,Aluminum (Al)-contained material,Inverted metamorphic (IMM),Four-junction solar cell
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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Cryostat setup for measuring spectral and electrical properties of light-emitting diodes at junction temperatures from 81 K to 297 K
摘要： We introduce a cryostat setup for measuring fundamental optical and electrical properties of light-emitting diodes (LEDs). With the setup, the cryostat pressure and the LED properties of the forward voltage, junction temperature, and electroluminescence spectrum are monitored with temperature steps less than 1.5 K, over the junction temperature range of 81–297 K. We applied the setup to commercial yellow AlGaInP and blue InGaN LEDs. At cryogenic temperatures, the fine structure of the electroluminescence spectra became resolved. For the yellow LED, we observed the phonon replica at 2.094 eV that was located 87 meV below the peak energy at the junction temperature of 81 K. For the blue LED, we observed the cascade phonon replicas at 2.599 eV, 2.510 eV, and 2.422 eV with the energy interval of 89 meV. For both LED types, the forward voltage increased sharply toward the lower temperatures due to the increased resistivity of materials in the LED components. We found significant differences between the temperature dependent behaviors of the forward voltages, spectral peak energies, and bandgap energies of LEDs obtained from the Varshni formula. We also noted a sharp pressure peak at 180–185 K arising from the solid-vapor phase transition of water when the base level of the cryostat pressure was approximately 0.4 mPa.
关键词： spectral properties,light-emitting diodes,electrical properties,junction temperature,phonon replicas,cryostat setup
更新于2025-09-16 10:30:52
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Origin of Bypass Diode Fault in c-Si Photovoltaic Modules: Leakage Current under High Surrounding Temperature
摘要： Bypass diodes have been widely utilized in crystalline silicon (c-Si) photovoltaic (PV) modules to maximize the output of a PV module array under partially shaded conditions. A Schottky diode is used as the bypass diode in c-Si PV modules due to its low operating voltage. In this work, we systematically investigated the origin of bypass diode faults in c-Si PV modules operated outdoors. The temperature of the inner junction box where the bypass diode is installed increases as the ambient temperature increases. Its temperature rises to over 70 ?C on sunny days in summer. As the temperature of the junction box increases from 25 to 70 ?C, the leakage current increases up to 35 times under a reverse voltage of 15 V. As a result of the high leakage current of the bypass diode at high temperature, melt down of the junction barrier between the metal and semiconductor has been observed in damaged diodes collected from abnormally functioning PV modules. Thus, it is believed that the constant leakage current applied to the junction caused the melting of the junction, thereby resulting in a failure of both the bypass diode and the c-Si PV module.
关键词： diode junction melt,bypass diode of PV module,leakage current,temperature inside the junction box
更新于2025-09-12 10:27:22
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Thermomechanical Stress Distribution Analysis of Junction Box on Silicon Photovoltaic Modules Based on Finite Element Analysis
摘要： The electrical failure associated with concentration of heat and thermomechanical stress inside junction boxes is one of the main failure modes of photovoltaic (PV) modules. Three types of potting junction boxes with partial 72 Si cells PV panel are modeled under a constant current steady-state condition. The temperature distribution results are veri?ed through thermal dissipation tests. It is found that when one diode is in the ON-state, the split kind of junction box shows the highest temperature distribution on the surface, which is nearly 15 ?C higher than the other two types under 25 ?C with 11 A current applied. When three diodes are working, the other two types of junction box with three diodes inside will be intensely heated. The internal temperature distribution shows that bigger size and more copper coverage can help improve the thermal dissipation. Thermomechanical stress analysis based on the steady-state conditions is then carried out. The results show stress concentration on the side wall of the type I junction box while the other two types having conspicuous impact to the backsheet.
关键词： thermomechanical stress,temperature distribution,junction box,photovoltaic (PV),Finite element analysis
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing INTERNATIONAL CONFERENCE ON INVENTIVE MATERIAL SCIENCE APPLICATIONS : ICIMA 2019 - Coimbatore, India (25–26 September 2019)] INTERNATIONAL CONFERENCE ON INVENTIVE MATERIAL SCIENCE APPLICATIONS : ICIMA 2019 - 2-D hollow core photonic crystal fiber-type absorption layer for enhancement of efficiency and broad response in multi-junction solar cell
摘要： We present a numerical based approach to design a new 2-D hollow core photonic crystal (2-D HCPC) structure of hexagonal lattice arrangement with circular air holes on an Indium Tin Oxide (ITO) slab. We used this structure as an anti-re?ective coating (ARC) layer on top of a multi-junction (GaP/InP/Si) solar cell. Apart from the ARC layer a GaAs PhC as back re?ector (BR) is used in the MJSC structure. A unique approach by blending light trapping structures to enhance solar cell e?ciency and light harvesting capabilities for wavelength beyond 750 nm is the goal of the present work. Under AM1.5G condition, the simulation results of the 2-D HC-PC structure as an absorption layer when incorporated on the MJSC structure led to an improvement of 6.38% in cell e?ciency over the previously reported by the conventional/non-photonic MJSC structure. The absorption spectral response using the 2-D HCPC pattern on ITO as ARC on the MJSC is achieved beyond 1000 nm. An optimization study is also carried out by using InAs as core of the 2-D HCPC structure which resulted to an enhancement of cell e?ciency by 9.34% as compared to the conventional/non-photonic MJSC structure.
关键词： efficiency enhancement,2-D hollow core photonic crystal,anti-re?ective coating,multi-junction solar cell,light trapping
更新于2025-09-12 10:27:22
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Design of Curved Fresnel Lens with High Performance Creating Competitive Price Concentrator Photovoltaic
摘要： In this paper, the design of a curved Fresnel lens applying to the concentrator photovoltaic system is proposed by using the edge ray theorem, the Snell’s law, and the conservation of optical path length. The new structure of the curved Fresnel lens can improve significantly the uniformity of sunlight distribution over the solar cell while the concentration ratio can reach a high value of 900 times. The good uniform distribution can be obtained by using the novel idea. The novel idea is based on the uniform sunlight distribution of every groove of the lens so that the whole lens also distributes uniformly the sunlight beam over the receiver. The structure of the lens is built by two surfaces: input surface (or upper surface) as a part of spherical surface and output surface (or lower surface) that consists all grooves of the lens. Matlab program is used to design the input and the output surfaces of the lens. The input surface and the output surface are independent to each other in construction in Matlab. LighttoolsTM software is used to optimize the structure of the novel lens. Furthermore, LighttoolsTM is also used to perform a simulation to examine the efficiency of the lens in concentrator photovoltaic (CPV) system by using the light source with a wide spectrum of 380 – 1600 nm. The results show that the lens has an acceptance angle of 0.80 and good optical efficiency (>85%).
关键词： concentrator photovoltaic (CPV),Fresnel lens,solar energy,high concentration ratio,multi-junction solar cells,uniform irradiance distribution,CPV without secondary optical element (SOE)
更新于2025-09-12 10:27:22