共查询到20条相似文献，搜索用时 15 毫秒
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Juan M. Lpez‐Gonzlez Isidro Martín Pablo Ortega Albert Orpella Ramon Alcubilla 《Progress in Photovoltaics: Research and Applications》2015,23(1):69-77
Rear surface of high‐efficiency crystalline silicon solar cells is based on a combination of dielectric passivation and point‐like contacts. In this work, we develop a 3D model for these devices based on 2.2 Ωcm p‐type crystalline silicon substrates. We validate the model by comparison with experimental results allowing us to determine an optimum design for the rear pattern. Additionally, the 3D model results are compared with the ones deduced from a simpler and widely used 1D model. Although the maximum efficiency predicted by both models is approximately the same, large deviations are observed in open‐circuit voltage and fill factor. 1D simulations overestimate open‐circuit voltage because Dember and electrochemical potential drops are not taken into account. On the contrary, fill factor is underestimated because of higher ohmic losses along the base when 1D analytical model is used. These deviations are larger for relatively low‐doped substrates, as the ones used in the experimental samples reported hereby, and poor passivated contacts. As a result, 1D models could mislead to too short optimum rear contact spacing. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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超短脉冲光纤激光器工作原理及其测量 总被引：3，自引：0，他引：3
简要阐述了飞秒光纤激光器的基本概念，分析了锁模技术的原理。结合被动锁模光纤激光器的基本构成，描述飞秒脉冲的产生过程。此外，还对飞秒脉冲测量作了介绍。 相似文献
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激光脉冲频率对纳米Si晶薄膜形貌的影响 总被引：5，自引：5，他引：5
在气压为10 Pa的惰性气体Ar环境下,采用XeCl准分子激光器(波长308 nm),调整激光单脉冲能量密度为4 J/cm2,激光烧蚀电阻率为3000Ω.cm的高纯单晶Si靶,在玻璃或Si衬底上沉积制备了纳米Si晶薄膜。实验中靶和衬底间距离保持为3 cm,对衬底既没有加温也没有冷却。拉曼(Raman)谱测量结果表明,所制备的薄膜中已有纳米Si晶粒形成。保持脉冲总数不变,分别取激光脉冲频率为1 Hz,3 Hz,10 Hz和20 Hz,相应沉积时间约为10 min,3.3 min,1 min和0.5 min,采用扫描电子显微镜(SEM)观察所得样品的表面形貌,不同脉冲频率下的结果比较显示,脉冲频率越大,制备的纳米Si晶薄膜的平均晶粒尺寸就越小,晶粒尺寸分布也越均匀。沉积动力学过程的非线性是导致实验出现该结果的原因。 相似文献
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A method to determine the transient waveform of ultra‐wideband (UWB) pulses at various stages of propagation and scattering is developed based on the reconstruction of incident wave and one of the known results for continuous waves. By using this method, the transmitting power of a UWB pulsed dipole antenna and the loss due to rainfall scattering are calculated, and the feasibility for short‐ and moderate‐range communication applications is discussed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Vinay Budhraja Bhushan Sopori Nuggehalli Ravindra Durgamadhab Misra 《Progress in Photovoltaics: Research and Applications》2014,22(12):1256-1266
We have extended a previous model for calculating the effects of dislocations on the characteristics of a Si solar cell to include the effects of front and back surface recombination. This improved dislocation model uses Green's function approach to solve the three‐dimensional continuity equation of the minority carriers with suitable boundary conditions corresponding to surface recombination at the n and p sides. The dislocations are considered to be localized lines, extending perpendicular to the front and back surfaces of the cell and having a recombination velocity. We discuss effect of several parameters such as bulk dislocation density, minority carrier diffusion length in p and n regions on the J‐V characteristics, and spectral response of the cell. It is shown that these results agree well with previously published, experimental data. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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恒弹性合金的加工对表面质量和加工精度的要求越来越高,为了实现对恒弹合金的精密定量去除,本文探索了采用飞秒激光烧蚀的加工新方法。首先,分析计算了在高强度飞秒激光辐照加工下,恒弹性合金材料的烧蚀阈值;其次,实验研究了飞秒激光脉冲能量和脉冲个数对该材料上烧蚀加工微坑的直径和深度的影响,结果表明：恒弹性合金的飞秒激光烧蚀阈值为0.167 J/cm2;可以通过增大脉冲能量来增大烧蚀坑直径,通过增大脉冲数来增大烧蚀坑深度。脉冲烧蚀坑直径上限为150.64 μm,运用飞秒激光旋切加工方法,可获得直径为500 μm的微孔,提高了飞秒激光烧蚀加工的能力。 相似文献
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Jia Chen Jan Deckers Patrick Choulat Izabela Kuzma‐Filipek Monica Aleman Angel Uruena De Castro Zhe Ren Du Filip Duerinckx Bram Hoex Jozef Szlufcik Jef Poortmans Armin G. Aberle 《Progress in Photovoltaics: Research and Applications》2015,23(12):1706-1714
n‐type silicon wafer solar cells are receiving increasing attention for industrial application in recent years, such as the n‐type rear‐junction Passivated Emitter Rear Totally‐diffused (PERT) solar cells. One of the main challenges in fabricating the n‐PERT solar cells is the opening of the rear dielectric for localized contacts. In this work laser ablation is applied to locally ablate the rear dielectric. We investigate the laser damage to the emitter at the laser‐ablated regions using the emitter saturation current density, J0e,laser, extracted by two approaches. J0e,laser is observed to be injection dependent due to high J02 recombination caused by laser damage to the space charge region. By using the optimized laser ablation parameters, n‐PERT solar cells with an efficiency of up to 21.0% are realized. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Daisuke Sato Kan‐Hua Lee Kenji Araki Taizo Masuda Masafumi Yamaguchi Noboru Yamada 《Progress in Photovoltaics: Research and Applications》2019,27(6):501-510
A low‐concentration static III‐V/Si partial concentrator photovoltaic (CPV) module for area‐limited car roofs was designed and experimentally demonstrated. The concentrator lens geometry was optimized for an incidence‐angle dependency of annual global irradiance on a car‐roof (horizontal‐flat) surface by considering arbitrary car orientations. The designed lens with a geometrical concentration ratio of 3.5× for III‐V triple‐junction (3‐junction) cells can collect 46.6% and 36.4% of the annual irradiation onto a III‐V 3‐juction and Si cells, respectively, which are located under the III‐V cell. The module design was validated by indoor and outdoor tests using a prototype submodule. The results show that the present module can potentially achieve up to 27.3% annual module efficiency, as projected from the actual daily submodule efficiency of 20.8% assuming state‐of‐the‐art record cell efficiency. Furthermore, the outdoor test on a real curved car roof demonstrated that the effect of the curved surface on the power generation performance is comparable with that of a conventional PV module. 相似文献
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Mikio Taguchi Akira Terakawa Eiji Maruyama Makoto Tanaka 《Progress in Photovoltaics: Research and Applications》2005,13(6):481-488
We have achieved a very high conversion efficiency of 21·5% in HIT cells with a size of 100·3 cm2. One of the most striking features of the HIT cell is its high open‐circuit voltage Voc, in excess of 710 mV. This is due to the excellent surface passivation at the a‐Si/c‐Si heterointerface realized by Sanyo's successful technologies for fabricating high‐quality a‐Si films and solar cells with low plasma damage processes. We have studied ways to treat the surface to produce a good interface throughout our fabrication processes. We have also investigated the deposition conditions of a‐Si layers for optimizing the barrier height for the minority carriers in the heterojunction. Our approach for obtaining HIT cells with a high Voc is reviewed here. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Simon Rommel Elizaveta P. Grakhova Antonio Jurado‐Navas Albert Kh. Sultanov Juan José Vegas Olmos Idelfonso Tafur Monroy 《International Journal of Communication Systems》2018,31(1)
This paper addresses impulse‐radio ultra‐wideband (IR‐UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well‐known shapes such as the Gaussian, root‐raised cosine, hyperbolic secant, and the frequency B‐spline wavelet are used to form linear combinations of component pulses, shaped to make efficient use of the spectral emission mask. Analytical BER values are derived using a Nakagami‐m model, and good agreement is found with the experimentally obtained BER. The proposed pulse shapes allow IR‐UWB transmission with BERs below the limit for a 7% overhead forward error correction, achieving distances of up to 6.5 m at 1 Gbit/s, 4.5 m at 1.25 Gbit/s, and 1 m at Gbit/s. These results confirm the viability of IR‐UWB transmission under the strict regulations of the Russian spectral emission mask. 相似文献
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This paper presents a numerical model, which quantitatively demonstrates that ablation and partial recondensation of the dopant precursor layer are some of the dominating physical processes in laser doping (LD) of crystalline silicon. Our pulsed LD process uses a line focused laser beam, enabling the creation of solar cell emitters without the generation of dislocations, if the width w of the short axis of the line focus is w < 10 μm. The concentration profiles of the dopant atoms strongly depend on the pulse energy density Ep, the pulse to pulse separation Δx and the number of laser scans Ns. By comparing measured with modeled concentration profiles, we are able to evaluate the ablation width as well as the amount of the ablated precursor layer. In case of a sputtered phosphorus precursor layer, the ablation width wa is wa = 6 μm, whereas the width of the molten silicon layer wm is wm = 5 μm. The model also explains the dependence of experimental dopant concentration profiles on the number of subsequent laser scans Ns and pulse to pulse separation Δx. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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M. Ochoa E. Barrign L. Barrutia I. García I. Rey‐Stolle C. Algora 《Progress in Photovoltaics: Research and Applications》2016,24(10):1332-1345
The main limiting factors of multijunction solar cells operating under ultra‐high concentration (>1000 suns) are examined by means of 2D physically based numerical modelling. The validation of the model is carried out by fitting calibrated light concentration measurements. Because the series resistance is the most important constraint in the electrical performance of the solar cell under ultra‐high irradiance, it is analysed and quantified detailing different contributions such as: (i) the electrical properties of the emitter; (ii) window layer of the top cell; and (iii) the band discontinuities formed at heterojunctions. We found the role of window layer to be important at very high concentrations (above 700 suns), while at ultra‐high concentrations, (above 1000 suns) a gain in efficiency (~ 1% absolute) can be obtained by a proper structural design of the window layer. In the case of the heterojunctions included in the multijunction solar cell, the impact of a high‐band offset can be mitigated by increasing the doping level density thus favouring the tunnelling effect. Moreover, the influence of different recombination mechanisms and high‐injection effects at ultra‐high irradiance is discussed. Finally, an optimisation of the complete solar cell taking into account the ohmic contacts to work under ultra‐high irradiances (from 1000 to 5000 suns) is presented as well as the implications on the use of ultra‐high irradiance in different multijunction solar cell architectures. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Reza Vatan Meidanshahi Chaomin Zhang Yongjie Zou Christiana Honsberg Stephen M. Goodnick 《Progress in Photovoltaics: Research and Applications》2019,27(8):724-732
Epitaxially grown single crystal GaP on Si is of considerable interest due to being nearly lattice matched to Si, making it attractive for III‐V/Si solar cells. GaP has been used as a buffer layer for III‐V/Si solar cells and also in selective contact Si solar cells. The performance and functionality of such devices are strongly influenced by the presence of localized states at the GaP/Si interface. Here, we examine the electronic structure of GaP/Si(001) heterojunctions and the effect of hydrogen (H) passivation at the interface, in contrast to interface mixing, through density functional theory calculations. Our calculations show that due to the heterovalent mismatch nature of the GaP/Si interface, there is a high density of localized states at the abrupt GaP/Si interface due to the excess charge associated with heterovalent bonding, as reported elsewhere. We find that the addition of H leads to additional bonding at the interface, which mitigates the charge imbalance, and greatly reduces the density of localized states, leading to a nearly ideal heterojunction. A similar result is found with a completely intermixed interface (alternating cation and anion bonding) in terms of low interface state density. However, when the intermixing occurs through single‐layer or double‐layer terraces, the benefits of intermixing are lost and the interface state density reverts more to the abrupt interface case. 相似文献