Papers by Keyword: Silicon Solar Cell

Abstract: Core-shell nanocrystals are utilized to improve vitality conversion efficiency of Si based solar cells. In the present work, a study of synthesis and characterization of photo luminescent, down-shifting, core-shell CdSe/CdS quantum dots is introduced. The QD^,s absorb in the UV range (350nm) of the solar spectrum and emit photons with wavelengths centered at (574 nm). Calculated energy gap is (2.16 eV), which is well suited for Silicon absorption and electron-hole pair generation. The grain size is ranged between (1.814 and 3.456 nm). Results show that the cell efficiency is improved from (8.81%) (For a reference silicon solar cell) to (10.07%) (For a CdSe/CdS QD deposited directly on the surface of the solar cell). This improvement is referred to the spreading of the absorbed solar radiation over the spectral response of the Si solar cell.

Abstract: The main energy losses in solar cells are related to spectral losses where high energy photons are not used efficiently, and energy is lost via thermalization which reduces the solar cell’s overall efficiency. A way to tackle this is to introduce a luminescent down-shifting layer (LDS) to convert these high energy photons into a lower energy bracket helping the solar cell to absorb them and thus generating a greater power output. In this paper, lumogen dye Violet 570 has been used as LDS coated films of 10μm and 60μm placed on top of Si solar cells. The dye was incorporated into polymer films of Polyvinyl Butyral (PVB) and Polymethyl Methacrylate (PMMA) after which they were tested for their absorption, transmission and emission properties. Once optimised layers had been determined, they were deposited directly onto silicon solar cells and the external quantum efficiency (EQE) of the Si solar cells were measured with and without the LDS layers. The resulting graphs have shown an increase of up to 2.9% in the overall EQE efficiency after the lumogen films had been applied.

Abstract: Stain etching of silicon solar cells in HF-FeCl₃-H₂O solutions as a last step in the processing sequence is reported. The etching was carried out without protecting the screen printed contacts. Following optimization of the solution composition and using very short etching times to alleviate the contact degradation problem, the solar cell weighted reflectance (R_w) between 400 and 1100 nm could be reduced from 38.23% to 11.54%. For the best small area cell (~20 cm²), the PS antireflective layer led to a relative improvement of 62.74% in the short-circuit current density, the FF was enhanced by 5.5% absolute, the open-circuit voltage was increased by 1.2 mV and the cell conversion efficiency was raised by 4.1% absolute from 5.4% to 9.5%. The best large area cell (~78 cm²) shows the following changes after porous layer formation: a relative improvement of 45.43% in the short-circuit current density, an improvement in the FF of 7.4% absolute, an increase in the open-circuit voltage by 7.5 mV and an enhancement in the cell efficiency by 4.0% absolute from 6.2% to 10.2%. This method shows a great potential for the cost-effective reduction of reflectance losses in industrial silicon solar cell manufacturing.

Abstract: Optical losses chiefly effect the power from a solar cell by lowering the short-circuit current. There are a number of ways to reduce the optical losses, which includes top contact coverage of the cell surface can be minimized, anti-reflection coatings can be used on the top surface of the cell, reflection can be reduced by surface texturing, and the optical path length in the solar cell may be increased by a combination of surface texturing and light trapping. This work discusses all of the methods to reduce optical losses of silicon solar cells. Surface texturing, either in combination with an anti-reflection coating or by itself, can be used to minimize reflection, but the large reflection loss can be reduced significantly via a suitable anti-reflecting coatings. Significant improvement of the short circuit current after light trapping design was observed. In addition to these methods, top contact design of silicon solar cells is important. The design of the top contact involves the minimization of the finger and busbar resistance, and the overall reduction of losses associated with the top contact.

Abstract: This work presents study of both the antireflection coatings on silicon solar cells and surface texture of silicon solar cell, with the aim to prepare high quality Si solar cells. Surface texturing, either in combination with an anti-reflection coating or by itself, can be used to minimize reflection, but the large reflection loss can be reduced significantly via a suitable anti-reflecting coatings. Significant improvement of the short circuit current after anti-reflecting coatings was observed. It is found that the currentvoltage characteristic with a double-layer anti-reflecting coatings is better than that with a single-layer anti-reflecting coatings. Depositing a multilayer on the textured surface reduces the large reflection loss significantly. The short circuit current of silicon solar cells has significant improvement after depositing anti-reflecting coatings on textured surface silicon, and it increases the efficiency of the Si solar cells.

Abstract: We demonstrate experimentally the enhanced performance of the plasmonic silicon solar cell by using a nano-sized indium-particles and different thickness of TiO2 space layer structure. The optical reflectance, dark and photo current-voltage, and external quantum efficiency are measured and compared at each stages of processing. The conversion efficiencies enhancing of 17.78%, 27.5% and of 47.85% are obtained as the solar cell with indium nanoparticles on a 10-nm, a 30-nm and a 59.5-nm thick TiO2 space layer, respectively, compared to the solar cell without coated a TiO2 layer. Furthermore, the plasmonics conversion efficiency depend on the thickness of space layer are also demonstrated that the increasing by 15.46%, 12.1% and 6.08% for the solar cells with a 10-nm, 30-nm and 59.5-nm thick TiO2 space layer, respectively, were obtained.

Abstract: In this work, we present the simulation results of the technological parameters and the electrical characteristics of a crystalline silicon n⁺pp⁺ solar cell, using two-dimension (2D) software, namely TCAD Silvaco (Technology Computer Aided Design). TCAD Silvaco Athena is used to simulate various stages of the technology manufacturing, while TCAD Silvaco Atlas is used for the simulation of the electrical characteristics and the spectral response of the solar cell. The J-V characteristics and the external quantum efficiency (EQE) are simulated under AM 1.5 illumination. The conversion efficiency(η)of 16.06% is reached and the other characteristic parameters are simulated: the open circuit voltage (Voc) is of 0.63 V, the short circuit current density (Jsc) equals 30.54 mA/cm² and the form factor (FF) is of 0.83 for the n+pp+ solar cell with a silicon nitride antireflection layer (Si3N4). In order to highlight the importance of the back surface field (BSF), a comparison between two cells, one without BSF (structure n⁺p), the other with one BSF (structure n⁺pp⁺), was made. By creating a BSF on the rear face of the cell the short circuit current density increases from 28.55 to 30.54 mA/cm², the open circuit voltage from 0.6 to 0.63 V and the conversion efficiency from 14.19 to 16.06%. A clear improvement of the spectral response is obtained in wavelengths ranging from 0.65 to 1.1 µm for the solar cell with BSF.

Abstract: This paper presents the numerical analysis of the velocity distribution in for a Fully Automatic Horizontal Diffusion Furnace for manufacturing Silicon Solar Cells. Diffusion and convection usually are interconnected in physics world, while convection is directly connected with flow velocity. Therefore, in a diffusion oven, the velocity of the gas(es) surrounding the wafer zone would play an important role in the quality of the process. A more uniform laminar flow surrounding the area, should in fact results in more consistent wafer quality. Therefore, the focus of the study is to compare the velocity field in the neighboring area, for different arrangement of gas intake. Numerical simulation has been conducted to provide guidance of designing the gas supply tube and the nozzles. Three dimensional, Steady State Fluid Dynamics analyses have been made. From the results of the simulation, the supply gas velocity distribution is very sensitive to the parameters. Gas supply line design with variable nozzle diameters form 2.0 to 3.5 provides the better gas velocity distribution, ensuring fresh gas to the wafer zone with gentle laminar flow in this study.

Abstract: PC1D software, which was developed by the University of New South Wales, has been used to simulate photovoltaic properties of crystalline semiconductor devices. The paper focuses on the simulation of silicon solar cell by PC1D. The simulation of silicon solar cell is carried out by setting up key parameters, which include device area, thickness, band gap, etc. Several important characteristics of silicon solar cells are obtained by simulation.

Abstract: Back–side diffraction gratings enhance a solar cell’s near–band–gap response by diffracting light into higher orders and thereby reducing front–side escape losses. The resulting increased photon absorption and carrier generation improves short–circuit current densities and solar cell efficiencies. Combining rigorous coupled–wave analysis and ray tracing yields a three–dimensional, polarization sensitive optical model to calculate Si absorbance, front–side and back–side losses. For industrially used, pyramidally textured, 180 μm Si solar cells with 85 nm SiN_x anti–reflection coating, the application of an optimized back–side grating enhances the short–circuit current density by ≈ +1 mA/cm², a relative increase of ≈ +2.7 %.