APPLIED PHOTOVOLTAICS第三章

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《应用光学》期末考试复习课件

《应用光学》期末考试复习课件
Applied Optics
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本门课程的主要学习内容
第一章 几何光学基本原理 第二章 共轴球面系统的物像关系 第三章 眼睛和目视光学系统 第四章 平面镜棱镜系统 第五章 光学系统中成像光束地选择
第六章 辐射度学和光度学基础
第八章 光学系统成像质量评价
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第一章 几何光学基本原理
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物像位置
物像大小
y nl
y nl
牛顿公式
高斯公式
f ' f 1 l' l
1、垂轴放大率 2、轴向放大率
3、角放大率
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要点回顾
1.物像空间不变式
Jnuy n'u'y'
2.物方焦距和像方焦距的关系
3.三种放大率之间的关系
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要点回顾
一、物像位置公式 1、牛顿公式 2、高斯公式
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第二章 共轴球面系统的物像关系
本章内容:共轴球面系统求像。由 物的位置和大小求像的位置和大小
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§2-5 共轴理想光学系统的基点—主平面和焦点
一. 放大率β=1的一对共轭面—主平面 二. 无限远的轴上物点和它所对应的像点F‘—像方焦点
三. 无限远的轴上像点和它所对应的物点F—物方焦点
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§2-5 共轴理想光学系统的基点—主平面和焦点
PPT学习交流
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§2-5 共轴理想光学系统的基点—主平面和焦点
问题
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§2-8 用作图法求光学系统的理想像
理想光学系统

期刊分区

期刊分区

APPL THERM ENG BIOENERG RES BIOFUEL BIOPROD BIOR BIOMASS BIOENERG BIORESOURCE TECHNOL COMBUST FLAME ENERG BUILDINGS ENERG CONVERS MANAGE ENERG FUEL FUEL FUEL PROCESS TECHNOL IEEE T ENERGY CONVER INT J GREENH GAS CON INT J HYDROGEN ENERG J POWER SOURCES P COMBUST INST RENEW SUST ENERG REV SOL ENERG MAT SOL C WIND ENERGY AAPG BULL CHEM ENG PROCESS ENERG POLICY ENERGY FUEL CELLS GCB BIOENERGY IET RENEW POWER GEN
J COMPOS CONSTR J COMPUT CIVIL ENG J CONSTR STEEL RES J HYDRAUL ENG-ASCE J HYDRAUL RES J HYDRO-ENVIRON RES J HYDROINFORM J HYDROL ENG J IRRIG DRAIN E-ASCE J MAR SCI TECH-JAPAN J SHIP RES J STRUCT ENG-ASCE J WATER RES PL-ASCE J WATERW PORT C-ASCE J WIND ENG IND AEROD OCEAN ENG SMART STRUCT SYST STRUCT CONTROL HLTH STRUCT INFRASTRUCT E THIN WALL STRUCT TUNN UNDERGR SP TECH ACI STRUCT J ADV STEEL CONSTR ADV STRUCT ENG ARCH CIV MECH ENG BAUINGENIEUR-GERMANY

Modern Application of mooc课后章节答案期末考试题库2023年

Modern Application of mooc课后章节答案期末考试题库2023年

Modern Application of Optoelectronic Technology_南京邮电大学中国大学mooc课后章节答案期末考试题库2023年1.Reconstructive spectrometer is based on compressive sensing theory.参考答案:正确2.Photoconductive detector gain depends on the difference of electron andhole drift speed参考答案:正确3.As tandem structure can increase solar cell efficiency, so we can add as manycells as possible to increase the overall absorption and energy conversionefficiency.参考答案:错误4.The solar cell performance can be degraded by参考答案:Series resistance_Defects in semiconductors_Shunt resistance5.The optical transition in silicon devices is usually indirect参考答案:正确6.Write the bandgap (300k) of silicon _______ eV.参考答案:1.117.The commercial solar cell panels are still dominated by silicon photovoltaics.参考答案:正确D means __________________________参考答案:charge coupled device9._____________________are the study and application of _________________ devices andsystems that source, detect and control ______________.参考答案:Optoelectronics, electronic, photon##%_YZPRLFH_%##Optoelectronics, electronic, light10.Which of the following factors affect the LED output spectrum?参考答案:Operation temperature_Semiconductor bandgap_Dopingconcentration_Applied voltage/current11.Conventional spectrometers used in laboratories are参考答案:Based on dispersive optics_High resolution12.Some typical research results show that graphene hybrid photodetectors can参考答案:Cover a wide detection bandwidth from UV to MIR._Have highresponsivity_Use both planar and vertical heterostructures._Have high detectivity13.The equation to express photoelastic effect is【图片】, which means therefractive index changes with strain参考答案:正确14.What are the four typical layers of optical fibers?____________,___________,____________,_____________.参考答案:core, cladding, protective polymeric coating, buffer tube15.Second harmonic generation happens when an intense light beam offrequency ω passing through an appropriate crystal (e.g., quartz) generates a light beam of half the frequency, 1/2ω参考答案:错误16.The two regimes in acousto-optic modulators are Raman-Nath regimeand___________参考答案:Bragg regime17.Optically anisotropic crystals are called __________ because an incident lightbeam may be doubly refracted. There is also a special direction in abirefringent crystal, called the optic axis.参考答案:birefringent18._____________ is the rotation of the plane of polarization by a substance参考答案:optical activity19.What efficiency is typical of a commercial PERC solar panel?参考答案:20%20.The advantages of perovskite materials include参考答案:High quantum yields_Low-cost_High quantum yields21.Typical optoelectronic process includes参考答案:Light transmission_Light modulation_Light detection_Light generation22.The two operation principles of photonic crystal fibers are ___________________and _____________________.参考答案:total internal reflection, photonic bandgap23.The propagation modes in waveguide can be classified in terms of____________________(TE) mode and ____________________(TM) mode?参考答案:transverse electric field, transverse magnetic field24.Kerr effect can be used to induce birefringence参考答案:正确25.The lattice constant of AlGaAs alloy follows nonlinear mixing rule参考答案:错误26.Which of the following is not a challenge for 2D semiconductor technology?参考答案:Materials choice27.In the space charge region, a high doping concentration results a shortdepletion width参考答案:正确28.CMOS means __________________________参考答案:complementary metal oxide semiconductor29.Photodetectors convert ___________________ to an electrical signal such asa____________________.参考答案:light, voltage or current##%_YZPRLFH_%##photon, voltage or current。

OPTICS EXPRESS A367 2010 Fundamental limit of light trapping in grating

OPTICS EXPRESS A367 2010 Fundamental limit of light trapping in grating

References and links
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. A. Goetzberger, “Optical confinement in thin Si-solar cells by diffuse back reflectors,” in Fifteenth IEEE Photovoltaic Specialists Conference, p. 867–870 (1981). E. Yablonovitch, “Statistical ray optics,” J. Opt. Soc. Am. A 72(7), 899–907 (1982). P. Campbell, and M. A. Green, “The limiting efficiency of silicon solar-cells under concentrated sunlight,” IEEE Trans. Electron. Dev. 33(2), 234–239 (1986). E. Yablonovitch, and G. D. Cody, “Intensity enhancement in textured optical sheets for solar cells,” IEEE Trans. Electron. Dev. 29(2), 300–305 (1982). M. A. Green, “Lambertian light trapping in textured solar cells and light-emitting diodes: analytical solutions,” Prog. Photovoltaics 10(4), 235–241 (2002). R. A. Pala, J. White, E. Barnard, J. Liu, and M. L. Brongersma, “Design of Plasmonic Thin-Film Solar Cells with Broadband Absorption Enhancements,” Adv. Mater. 21(34), 3504–3509 (2009). A. Chutinan, and S. John, “Light trapping and absorption optimization in certain thin-film photonic crystal architectures,” Phys. Rev. A 78(2), 023825–023815 (2008). I. Tobías, A. Luque, and A. Marti, “Light intensity enhancement by diffracting structures in solar cells,” J. Appl. Phys. 104(3), 034502 (2008). Z. Yu, A. Raman, and S. Fan, “Fundamental limit of nanophotonic light trapping for solar cells,” arXiv:1004.2902v2 [physics.optics] (2010). /abs/1004.2902v2 H. A. Atwater, and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. 9(3), 205–213 (2010). D.-H. Ko, J. R. Tumbleston, L. Zhang, S. Williams, J. M. DeSimone, R. Lopez, and E. T. Samulski, “Photonic crystal geometry for organic solar cells,” Nano Lett. 9(7), 2742–2746 (2009). L. Tsakalakos, “Nanostructures for photovoltaics,” Mater. Sci. Eng. Rep. 62(6), 175–189 (2008). J. Zhu, Z. Yu, G. F. Burkhard, C.-M. Hsu, S. T. Connor, Y. Xu, Q. Wang, M. McGehee, S. Fan, and Y. Cui, “Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays,” Nano Lett. 9(1), 279– 282 (2009). B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, and C. M. Lieber, “Coaxial silicon nanowires as solar cells and nanoelectronic power sources,” Nature 449(7164), 885–889 (2007). E. Garnett, and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010). N. Senoussaoui, M. Krause, J. Müller, E. Bunte, T. Brammer, and H. Stiebig, “Thin-film solar cells with periodic grating coupler,” Thin Solid Films 451–452, 397–401 (2004). S. Mokkapati, F. J. Beck, A. Polman, and K. R. Catchpole, “Designing periodic arrays of metal nanoparticles for light-trapping applications in solar cells,” Appl. Phys. Lett. 95(5), 053115 (2009). L. Zeng, Y. Yi, C. Hong, J. Liu, N. Feng, X. Duan, L. C. Kimerling, and B. A. Alamariu, “Efficiency enhancement in Si solar cells by textured photonic crystal back reflector,” Appl. Phys. Lett. 89(11), 111111 (2006). D. M. Schaadt, B. Feng, and E. T. Yu, “Enhanced semiconductor optical absorption via surface plasmon excitation in metal nanoparticles,” Appl. Phys. Lett. 86(6), 063106 (2005).

Photovoltaic Power Generation

Photovoltaic  Power  Generation

PHOTOVOLTAIC POWER GENERATIONABSTRACTThis report is an overview of photovoltaic power generation. The purpose of the report is to provide the reader with a general understanding of photovoltaic power generation and how PV technology can be practically applied.There is a brief discussion of early research and a description of how photovoltaic cells convert sunlight to electricity. The report covers concentrating collectors, flat-plate collectors, thin-film technology, and building-integrated systems. The discussion of photovoltaic cell types includes single-crystal, poly-crystalline, and thin-film materials. The report covers progress in improving cell efficiencies, reducing manufacturing cost, and finding economic applications of photovoltaic technology. Lists of major manufacturers and organizations are included, along with a discussion of market trends and projections.The conclusion is that photovoltaic power generation is still more costly than conventional systems in general. However, large variations in cost of conventional electrical power, and other factors, such as cost of distribution, create situations in which the use of PV power is economically sound. PV power is used in remote applications such as communications, homes and villages in developing countries, water pumping, camping, and boating. Grid-connected applications such as electric utility generating facilities and residential rooftop installations make up a smaller but more rapidly expanding segment of PV use. Furthermore, as technological advances narrow the cost gap, more applications are becoming economically feasible at an accelerating rate.INTRODUCTIONThis report is the result of Gale Greenleaf’s October 19, 1998 request for proposal. Bill Louk and Tom Penick responded to her request with a proposal, dated October 30, 1998, to continue earlier research on photovoltaic power generation. The proposal was approved and resulted in continued research followed by a presentation on November 30, 1998 and this final report on photovoltaic power generation.PHOTOVOLTAIC TECHNOLOGY Scientists have known of the photovoltaic effect for more than 150 years. Photovoltaic power generation was not considered practical until the arrival of the space program. Early satellites needed a source of electrical power and any solution was expensive. The development of solar cells for this purpose led to their eventual use in other applications.DISCOVERY AND DEVELOPMENT OF PHOTOVOLTAIC POWERThe photovoltaic effect has been known since 1839, but cell efficiencies remained around 1% until the 1950s when U. S. researchers were essentially given a blank check to develop a means of generating electricity onboard space vehicles. Bell Laboratories quickly achieved 11% efficiency, and in 1958, the Vanguard satellite employed the first practical photovoltaic generator producing a modest one watt.In the 1960s, the space program continued to demand improved photovoltaic power generation technology. Scientists needed to get as much electrical power as possible from photovoltaic collectors, and cost was of secondary importance . Without this tremendous development effort, photovoltaic power would be of little use today.POWER OUTPUT AND EFFICIENCY RATINGSThe figures given for power output and efficiency of photovoltaic cells, modules, and systems can be misleading. It is important to understand what these figures mean and how they relate to the power available from installed photovoltaic generating systems.Power RatingsPhotovoltaic power generation systems are rated in peak kilowatts (kWp). This is the amount of electrical power that a new, clean system is expected to deliver when the sun is directly overhead on a clear day. We can safely assume that the actual output will never quite reach this value. System output will be compromised by the angle of the sun, atmospheric conditions, dust on the collectors, and deterioration of the components. When comparing photovoltaic systems to conventional power generation systems, one should bear in mind that the PV systems are only productive during the daytime. Therefore, a 100 kW photovoltaic system can produce only a fraction of the daily output of a conventional 100 kW generator.Efficiency RatingsThe efficiency of a photovoltaic system is the percentage of sunlight energy converted to electrical energy. The efficiency figures most often reported are laboratory results using small cells. A small cell has a lower internal resistance and will yield a higher efficiency than the larger cells used in practical applications. Additionally, photovoltaic modules are made up of numerous cells connected in series to deliver a usable voltage. Due to the internal resistance of each cell, the total resistance increases and the efficiency drops to about 70% of the single-cell value. Efficiency is higher at lower temperatures. Temperatures used in laboratorymeasurements may be lower than those in a practical installation. CONVERTING SUNLIGHT TO ELECTRICITYA typical photovoltaic cell consists of semiconductor material (usually silicon) having a p-n junction as shown in Figure 1. Sunlight striking the cell raises the energy level of electrons and frees them from their atomic shells. The electric field at the p-n junction drives the electrons into the n region while positive charges are driven to the p region. A metal grid on the surface of the cell collects the electrons while a metal back-plate collects the positive charges.Figure 1.How solar cells workThin Film TechnologyThin-film solar cells are manufactured by applying thin layers of semiconductor materials to a solid backing material. The composition of a typical thin-film cell is shown in Figure 2. Sunlight entering the intrinsic layer generates free electrons. The p-type and n-type layers create an electric field across the intrinsic layer. The electric field drives the free electrons into the n-type layer while positive charges collect in the p-type layer. The total thickness of the p-type, intrinsic, and n-type layers is about one micron. Although less efficient than single- and poly-crystal silicon, thin-film solar cells offer greater promise for large-scale power generation because of ease of mass-production and lower materials cost. Thin-film is also suitable for building-integrated systems because the semiconductor films may be applied to building materials such as glass, roofing, and siding.Figure 2 Typical thin-film amorphous silicon constructions Using thin films instead of silicon wafers greatly reduces the amount of semiconductor material required for each cell and therefore lowers the cost of producing photovoltaic cells. Gallium arsenide (GaAs), copper indium diselenide (CuInSe2), cadmium telluride (CdTe) and titanium dioxide (TiO2) are materials that have been used for thin film PV cells. Titanium dioxide thin films have been recently developed and are interesting because the material is transparent and can be used for windows.Tin OxideTin oxide is a conductive material that is transparent when in a thin layer. Tin oxide is used in place of a metallic grid for the top layer of thin film photovoltaic sheets.Amorphous Silicon (a-Si)Amorphous (uncrystallized) silicon is the most popular thin-film technology. It is prone to degradation and produces cell efficiencies of 5-7%. Double- and triple-junction designs raise efficiency to 8-10%. The extra layers capture different wavelengths of light. The top cell captures blue light, the middle cell captures green light, and the bottom cell captures red light. Variations include amorphous silicon carbide (a-SiC), amorphous silicon germanium (a-SiGe), microcrystalline silicon ( c-Si), and amorphous silicon-nitride (a-SiN).Cadmium Telluride (CdTe) and Cadmium Sulphide (CdS) Photovoltaic cells using these materials are under development by BP Solar and Solar Cells Inc .Poly-crystalline SiliconPoly-crystalline silicon offers an efficiency improvement over amorphous silicon while still using only a small amount of material.Copper Indium Diselenide and Copper Indium Gallium DiselenideThese materials are currently being investigated, and have not been used commercially for photovoltaics.Concentrating CollectorsBy using a lens or mirror to concentrate the sun’s rays on a small area, it is possible to reduce the amount of photovoltaic material required. A second advantage is that greater cell efficiency can be achieved at higher light concentrations. To accommodate the higher currents in the photocells, a larger metallic grid is used. For example, in a system with a 22X concentration ratio, the grid covers about 20% of the surface of the solar cell. To prevent this from blocking 20% of the sunlight, a prism is used to redirect sunlight onto the photovoltaic material, as shown in Figure 3. A second problem is the higher temperatures of a concentrating system. The cells may be cooled with a heat sink or the heat can be used to heat water.Figure 3.Prism cover for high-current solar cellOnly direct sunlight, not scattered by clouds or haze, can be concentrated. Therefore, the concentrating collectors are less effective in locations that are frequently cloudy or hazy, such as coastal areas.CONCLUSIONPhotovoltaic efficiency and manufacturing costs have not reached the point that photovoltaic power generation can replace conventional coal-, gas-, and nuclear-powered generating facilities. For peak load use (no battery storage), the cost of photovoltaic power is around two to four times as much as conventional power. (Cost comparisons between photovoltaic power and conventionally generated power are difficult due to wide variations in utility power cost, sunlight availability, andnumerous other variables.)REFERENCES[1] “The History of PV,” /pvhistory.html, November 15, 1998.[2] Mark Hammonds, “Getting Power from the Sun, Solar Power,” Chemistry and Industry, no. 6, p. 219, March 16, 1998.[3] "Energy Conversion: Development of solar cells" Britannica Online.:180/cgi-bin/g?DocF=macro/5002/13/245.html, October 21, 1998.[4] Kenneth Zweibel and Paul Hersch, Basic Photovoltaic Principles and Methods, New York: Van Nosstrand Reinhold Company, Inc., 1984.[5] “Volume 3: The World PV Market to 2010,” Photovoltaics in 2010, Luxembourge: Office for Official Publications of the European Communities, 1996.[6] “Taking Off of New Photovoltaic Energy Revolution,” Japan 21st, May 1996.。

SiO2纳米球的粒径均一性研究及其在硅光学共振纳米柱阵列中的应用

SiO2纳米球的粒径均一性研究及其在硅光学共振纳米柱阵列中的应用

SiO2纳米球的粒径均一性研究及其在硅光学共振纳米柱阵列中的应用彭新村;王智栋;曾梦丝;刘云;邹继军;朱志甫;邓文娟【摘要】近年来,半导体纳米结构材料的光学共振效应作为一种重要的光调控手段被广泛应用于各类光电子器件.本文用改进的两步Stober法制备了粒径在270~330 nm之间的单分散二氧化硅纳米球,通过优化工艺参数有效改善了纳米球的粒径均一性.采用恒温加热蒸发引诱自组装方法将纳米球在硅半导体上自组装成单层膜作为掩膜,采用感应耦合等离子体技术刻蚀制备了硅纳米柱阵列并测试了其光反射谱.光谱结果表明直径在300~325 nm之间的硅纳米柱阵列可以激发四极子Mie光学共振,其在可见光波段的最低反射率低于5%,具有良好的光调控性能.【期刊名称】《无机材料学报》【年(卷),期】2019(034)007【总页数】7页(P734-740)【关键词】自组装纳米球;纳米阵列;光学共振【作者】彭新村;王智栋;曾梦丝;刘云;邹继军;朱志甫;邓文娟【作者单位】东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013;东华理工大学教育部核技术应用工程研究中心,南昌 330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013;东华理工大学江西省新能源工艺及装备工程技术中心,南昌 330013【正文语种】中文【中图分类】TN204纳米结构材料的光学共振效应作为一种重要的光调控手段引起了广泛关注[1-8]。

间接带隙硅(Si)半导体在可见光波段具有较高的折射率(>4)和较低的消光系数(<0.2), 其纳米结构材料对光具有较强的米氏散射作用, 能够激发米氏共振(Mie Resonances, MR)[9]。

应用光伏学题库

应用光伏学题库

一、选择题(在下列每题的四个选项中,只有一个选项是符合试题要求的。

请把答案填入答题框中相应的题号下。

每小题1分,共10分)二、填空题(本大题共10小题,每小题1分,共10分)§01. ★Photovoltaics (often abbreviated as PV ) is a simple and elegant method of harnessing the sun's energy .2. ★PV devices (solar cells) are unique in that they directly convert the incident solar radiation into electricity , with no noise, pollution or moving parts, making them robust, reliable and long lasting.3. ★Photovoltaics is the process of converting sunlight directly into electricity using solar cells .4. ★The first photovoltaic device was demonstrated in 1839 by Edmond Becquerel, as a young 19 year old working in his father‘s laboratory in Fra nce.5. ★The first practical photovoltaic device was demonstrated in the 1950s.6. ★★Research and development of photovoltaics received its first major boost from the space industry in the 1960s.§11. ★A photon is characterized by either a wavelength, denoted by λ, or equivalently an energy, denoted by E.2. ★★There is an inverse relationship between the energy of a photon (E ) and the wavelength of the light (λ) given by the equation: ,.3. ★★The photon flux is defined as the number of photons per second per unit area.4. ★★★The total power density emitted from a light source can be calculated by integrating the spectral irradiance over all wavelengths or energies of interest.5. ★★In the analysis of solar cells, the photon flux is often needed as well as the spectral irradiance.6. ★The blackbody sources which are of interest to photovoltaics, emit light in the visible region.7. ★★★The spectral irradiance from a blackbody is given by Plank's radiation law.8. ★★The peak wavelength of the spectral irradiance is determined by differentiating the spectral irradiance and solving the derivative when it equals 0. The result is known as Wien‗s Law: ()2900p m T λμ=.9. ★★★Solar radiation in space: sun H D R H ⨯=220.H sun =5.961×107W/m 2.10. ★The solar radiation outside the earth's atmosphere have been defined as a standard value called air masszero (AM0) and takes a value of 1.353 kW/m 2.11. ★The spectral irradiance from a blackbody at 6000 K (at the same apparent diameter as the sun when viewedfrom earth); from the sun‘s photosphere as observed just outside earth‘s atmosphere (AM0); and from the sun‘s photosphere after having passed through 1.5 times the thickness of earth‘s atmosphere (AM1.5G).12. ★★The Air Mass is defined as: ()θcos 1AM =,2h s 1AM ⎪⎭⎫ ⎝⎛+=. where θ is the angle from the vertical (zenithangle).13. ★★When the sun is directly overhead, the Air Mass is 1.14. ★The standard spectrum at the Earth's surface is called AM1.5G (the G stands for global and includes bothdirect and diffuse radiation) or AM1.5D (which includes direct radiation only), these calculations give approximately 970 W/m 2 for AM1.5G 。

Prog.+Photovolt-+Res.+Appl.+2007,15,603–612

Prog.+Photovolt-+Res.+Appl.+2007,15,603–612

Research Fabrication of Screen-PrintingPastes From TiO 2Powders forDye-Sensitised Solar CellsSeigo Ito,Peter Chen,Pascal Comte,Mohammad Khaja Nazeeruddin,Paul Liska,Pe´ter Pe ´chy and Michael Gra ¨tzel *y Laboratory of Photonique and Interfaces (LPI),Institute des Sciences et Ingenierie Chimiques (ISIC),E´cole Polytechnique Fe´de ´rale de Lausanne (EPFL),CH-1015Lausanne,Switzerland A preparation technique of TiO 2screen-printing pastes from commercially-availablepowders has been disclosed in order to fabricate the nanocrystalline layers withoutcracking and peeling-off over 17m m thickness for the photoactive electrodes of thedye-sensitised solar cells.A conversion efficiency of 8Á7%was obtained by using asingle-layer of a semi-transparent-TiO 2film.A conversion efficiency of 9Á2%wasobtained by using double-layers composed of transparent and light-scattering TiO 2films for a photon-trapping system.Copyright #2007John Wiley &Sons,Ltd.key words :titanium dioxide;nanocrystalline electrode;dye-sensitised solar cellsReceived 9January 2007;Revised 20March 2007INTRODUCTIONDye-sensitised solar cells (DSCs)are currently attracting academic and commercial interest as regenerative low-cost alternatives to conventional solid state devices.1,2So far,the best performing nanocrystalline-TiO 2electrodes have been fabricated by hydrothermal autoclaving and screen-printing deposition.3–5Screen-printing of TiO 2is a widespread industrially-applied method because of the fast-printing technique and of the coating facility with fine controlling of the position and thickness.Other applied fields are gas sensors (humidity,O 2,H 2,NO X ,CH X ,CO,etc.),ion sensors,piezoelectric devices,microfiltration membranes,Gamma-radiation sensors,electroluminescent devises,electrochromic display,antireflection coatings on silicon solar cells,microwave applications,photocatalyst coatings and so on.The nontoxicity of titanium dioxide,which is used in paints,cosmetics and health care products,adds advantages to the fields.The key point on the screen-printing is the quality and characteristics of TiO 2paste.For the best-performing TiO 2electrodes,the synthesis of TiO 2paste involves hydrolysis of Ti(OCH(CH 3)2)4in water at 2508C (70atms)for 12h,followed by conversion of the water to ethanol by three-times centrifugation.Finally,the ethanol is exchanged with a -terpineol by sonication and evaporation.3Totally,it takes 3days.Such a long-time procedure of TiO 2pastes is economically unsuitable for industrial production and has to be reduced.Towards this goal,several reports were published in order to fabricate screen-printing paste from a commercially-available TiO 2powder (P25,Degussa).6–9Most of the pastes were based on water and alcohols,which induce TiO 2aggregation and yielding poorly reproducible results in long-term experiments.On the other hand,a -terpineol-based PROGRESS IN PHOTOVOLTAICS:RESEARCH AND APPLICATIONSProg.Photovolt:Res.Appl.2007;15:603–612Published online 30May 2007in Wiley InterScience ()DOI:10.1002/pip.768*Correspondence to:Michael Gra ¨tzel,Laboratory of Photonique and Interfaces (LPI),Institute des Sciences et Ingenierie Chimiques (ISIC),E ´cole Polytechnique Fe ´de ´rale de Lausanne (EPFL),CH-1015Lausanne,Switzerland.y E-mail:michael.graetzel@epfl.chCopyright #2007John Wiley &Sons,Ltd.604S.ITO ET AL. pastes3–5are very stable at long-term and give very reproducible results for several years.However,a reported paste made from P25and a-terpineol did not give better DSCs than that of a water-based paste.9In this study,we have developed a new procedure which takes only4h to produce TiO2pastes with a-terpineol from commercially-available powders,resulting in DSCs with ca.9%conversion efficiencies. Moreover,the most important point of this work is to utilise the commercially-available TiO2particles for the high-efficiency DSCs,because the synthesis of the homemade TiO2particle demands the delicate techniques and consequently the different batch of TiO2particle might give different results.For the reproducible results, therefore,it is important to investigate a new fabrication method of TiO2paste from commercially-available particles.This report will be of great help for the people who are engaged with DSCs. EXPERIMENTALMaterialsThree kinds of commercially-available TiO2powders were used:P25(av.30nm by Brunauer-Emmett-Teller (BET),80%anatase(d¼21nm)and20%rutile(d¼50nm),via TiCl4-fumed gas synthesis,Degussa, Germany);ST21(av.25nm by BET,100%anatase,via sulfuric-acid synthesis,Ishihara Sangyo,Japan);ST41 (av.160nm by BET,100%anatase,via sulfuric-acid synthesis,Ishihara Sangyo,Japan).Two kinds of pure powders of ethyl celluloses(5–15mPas at5%in toluene:ethanol/80:20at25oC,#46070,Fluka;30–50mPas at 5%in toluene:ethanol/80:20at258C,#46080,Fluka)were dissolved beforehand in an ethanol solution(these powders of ethyl cellulose don’t contain toluene and ethanol which were mixed with ethyl cellulose just to show the specification results of viscosity).Each concentration of the ethyl cellulose was5wt%:the total amount of ethyl celluloses was10wt%in ethanol.4-tert-butylpyridine(Aldrich),acetonitrile(Fluka)and valeronitrile(Fluka)were purified by vacuum distillation.Guanidinium thiocyanate(Aldrich)and H2PtCl6(Fluka)were used as received.H2O was purified by distillation andfiltration(Milli-Q).TiCl4(Fluka)was diluted with water to2M at08C to make a stock solution, which was kept in a freezer and freshly diluted to40mm with water for each TiCl4treatment of the F-doped tin oxide(FTO)coated glass plates.Iodine(99Á999%,Superpur1,Merck)was used as received.The synthesis of cis-di(thiocyanato)-N,N’-bis(2,2’-bipyridyl-4-carboxylic acid-4’-tetrabutylammonium carboxy late)ruthenium (II)(N-719)and butylmethylimidazolium iodide(BMII)were reported in our previous paper.10,11The chromatographic purification of N-719was carried out three times on a column of Sephadex LH-20using the following procedure.4,5Preparation of TiO2pasteThe fabrication scheme for TiO2pastes was described in Figure1.At each step,liquids were added drop by drop into an alumina mortar,which is more stable than a porcelain one.The diameter of the mortar was ca.20cm.The condition was in the ambient air at room temperature.The TiO2powders stuck on the inside of the mortar should be removed by a plastic spatula in order to grind large aggregates.The TiO2dispersions in the mortar were transferred with excess of ethanol(100ml)to a tall beaker and stirred with a4cm long magnet tip at300rpm. The ultrasonic homogenisation was performed with using a Ti-horn-equipped sonicator(Vibra cell72408, Bioblock scientific).Anhydrous terpineol(Fluka)and the mixture solution of two ethyl celluloses in ethanol were added,followed by stirring and sonication.The contents in dispersion were concentrated by evaporator at 358C with120mbar atfirst.The pressure was evacuated until10mbar.The pastes werefinalised with a three-roller-mill grinder(EXAKT).In this scheme(Figure1),the coexistence of water and acetic acid was important.We tried another combination with nitric acid,hydrochloric acid,acetyl acetone,polyethylene glycol,triton X-100and so on. Without water and/or acetic acid,however,the porous-TiO2layers over10m m thickness were mechanically unstable and did not keep the structure after sintering due to the large cracks and peeling-up from substrate. Copyright#2007John Wiley&Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipWe speculate the reason as below.In order to make a good connection between TiO 2particles and between a TiO 2particle and SnO 2surface,hydroxides (–OH)have to be on the surface and make strong chemical bonding between each other by dehydration at sintering:M 1ÀOH þHO ÀM 2!M 1ÀO ÀM 2þH 2Owhere,M 1shows a titanium atom on a surface of a particle and M 2shows a titanium atom of another particle or a tin atom on a plate of transparent conductive oxide (TCO)substrate (F-doped tin oxide (FTO)glass).The water added at first can make the surface covered by hydroxides.At the same time,each particle has to be isolated from each other and not to be aggregated.The aggregates in matrix can make large shrinkage of the film at the sintering,resulting in the peering-off from the TCO substrate.The acetic acid can be adsorbed on the surface of TiO 2and prohibits each particle from the aggregation.At the same time,the proton (H þ)of acid can also be adsorbed on the surface and shifts the Zeta potential to positive,resulting in repelling the particles from each other.About the reproducibility,as long as the timing of adding,mixing and grinding the materials in the mortar is kept up,the result is quite reproducible (the data was not shown).However,by changing the timing,it can change.For example,if we add all of the ethanol in one time,it is very difficult to remove the aggregate.The paste can be a film peeled-off from the substrate or be a DSC electrode with a low photovoltaic efficiency.Preparation of nanocrystalline-TiO 2electrodesTo prepare the DSC working electrodes,the FTO glass used as current collector (Solar 4mm thickness,10V /&,Nippon Sheet Glass,Japan)was first cleaned in a detergent solution using an ultrasonic bath for 15min,and then rinsed with water and ethanol.After treatment in a UV-O 3system (Model No.256–220,Jelight Company,Inc.)for 18min,the FTO glass plates were immersed into a 40mm aqueous TiCl 4aqueous solution at 708C for 30min and washed with water and ethanol.A layer of paste was coated on the FTO glass plates by screen-printing (90T,Estal Mono,Schweiz.Seidengazefabrik AG Thal),kept in a clean box for 3min with ethanol so that the paste can relax to reduce the surface irregularity and then dried for 6min at 1258C.The screen characteristics areas Figure 1.Fabrication scheme of screen-printing paste from a nanocrystalline-TiO 2powderCopyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipFABRICATION OF SCREEN-PRINTING PASTES 605606S.ITO ET AL. follows:material,polyester;mesh count,90T mesh/cm(or230T mesh/inch);mesh opening,60m m;thread diameter,50m m;open surface,29Á8%;fabric thickness,83m m;theoretical paste volume,24Á5cm3mÀ2;K/KS volume,17Á0cm3mÀ2;weight,48g mÀ2.This screen-printing procedure(with coating,storing and drying)was repeated to change the thickness of the nanocrystalline-TiO2working electrode.For the single-layer electrode, the TiO2paste of ST21was used,resulting in a light-scatteringfilm.For the double-layer electrode,the paste of P25for the transparent layer was coated by screen-printing and dried at1258C,and then,the second layers of ST41for the light-scattering layer were deposited by screen-printing to4–5m m thickness.The electrodes coated with the TiO2pastes were gradually heated under an airflow at3258C for5min,at3758C for5min,at4508C for 15min and5008C for15min8C.After sintering,the surface area of the TiO2electrodes was measured precisely by a scanner with600dpi resolution in grey mode,followed by integration of the resulting image.4DSC assemblingAfter the size measurement,the TiO2film was treated with40mm TiCl4solution as described above,rinsed with water and ethanol and sintered at5008C for30min.At808C in the cooling,the TiO2electrode was immersed into a0Á5mM N-719dye solution in a mixture of acetonitrile and tert-butyl alcohol(volume ratio:1:1)and kept at room temperature for20–24h to complete the sensitiser uptake.To prepare the counter electrode,a hole was drilled in the FTO glass(LOF Industries,TEC15V/&,2Á2mm thickness)by sand blasting.The perforated sheet was washed with H2O as well as with a0Á1M HCl solution in ethanol and cleaned by ultrasound in an acetone bath for10min.After removing residual organic contaminants by heating in air for15min at4008C,the Pt catalyst was deposited on the FTO glass by coating with a drop of H2PtCl6solution(2mg Pt in1ml ethanol)and repeating the heat treatment at4008C for15min.The dye-covered TiO2electrode and Pt-counter electrode were assembled into a sandwich type cell and sealed with a hot-melt gasket of25m m thickness made of the ionomer Surlyn1702(Dupont).The aperture of the Surlyn frame was2mm larger than that of the TiO2area and its width was1mm.A drop of the electrolyte,a solution0Á60M BMII,0Á03M I2,0Á10M guanidinium thiocyanate and0Á50M4-tert-butylpyridine in the mixture of acetonitrile and valeronitrile(volume ratio:85:15))was put on the hole in the back of the counter electrode.The electrolyte was introduced into the cell via vacuum backfilling.The cell was placed in a small vacuum chamber to remove inside air.Exposing it again to ambient pressure causes the electrolyte to be driven into the cell.Finally,the hole was sealed using a hot-smelt ionomerfilm(Bynel4702,35m m thickness,Du-Pont) and a cover glass(0Á1mm thickness).Photovoltaic measurement of DSCLight reflection losses were eliminated using a self-adhesivefluorinated polymerfilm(ARKTOP,ASAHI GLASS)that served at the same time as a380nm UV cut-offfilter.Photovoltaic measurements employed an AM 1Á5solar simulator.The power of the simulated light was calibrated to be100mW cmÀ2by using a reference Si photodiode equipped with an IR-cutofffilter(KG-3,Schott),which was calibrated at three solar-energy institutes(ISE(Germany),NREL(USA),SRI(Switzerland)).4I-V curves were obtained by applying an external bias to the cell and measuring the generated photocurrent with a Keithley model2400digital source meter.The voltage step and delay time of photocurrent were10MV and40ms,respectively.RESULTS AND DISCUSSIONMorphology of screen-printed TiO2filmsFigure2shows SEM pictures of porous TiO2films.We can notice that the particles of P25contained small particles(anatase,20nm)and large particles(rutile,40nm).Compared with the pictures of TiO2films made via Copyright#2007John Wiley&Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipcolloidal synthetic routes (Figure 2g and h),the P25film contained no aggregates (Figure 2a),and was dispersed homogeneously over the large area (Figure 2b).On the other hand,ST21showed the small aggregates (ca .100nm,Figure 2c)and the large aggregates (micron-meter order,Figure 2d).The large aggregates of ST21were very difficult to be broken by this procedure and gave small cracks in the porous TiO 2layer (Figure 2d).The difference of the morphologies between P25and ST21was due to the synthesis method:fumed-TiCl 4and sulphuric-acid routes,respectively.ST41contained 50–200nm large particles (Figure 2e).The average was 160nm from BET data (measured by Ishihara Sangyo).Although ST41also was made by the sulphuric-acid synthesis,this layer was homogeneous over the large area (Figure 2f).Hence,the aggregations between ST41particles did not affect the surface morphology on a large scale.For the comparison with homemade TiO 2,we added the SEM pictures (Figure 2g and h).Although the aggregates about 200nm existed (in a white circle of Figure 2g)and we can find small dots in Figure 2h from the aggregate,the surface was very smooth and uniform over the large area (Figure 2h).Figure 3shows cross sections of nanocrystalline-TiO 2layers by surface-profiling method (Alphastep 550).Each layer was the single screen-printing using a 90T mesh.The layer of P25and ST41was relativelyflat Figure 2.SEM photographs of porous TiO 2films showing the surface morphology of P25(a,b),ST21(c,d),ST41(e,f)andhomemade TiO 2(d ¼20nm)(g,h)with two types of magnification:120000Â(a,c,e,g)and 5000Â(b,d,f,h)Copyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipFABRICATION OF SCREEN-PRINTING PASTES 607compared with that of ST21.This phenomenon reflected the morphology which was observed by SEM (Figure 2).The flatness of P25and ST41layers reflect the homogeneous dispersion of particles.On the other hand,the roughness of ST21layer reflects the aggregations (Figure 2d).Figure 4a shows the photograph of screen-printed layers with a background of garden plants.The P25film was transparent and pale blue.We can see the clear image of the background.The ST21film was semi-transparent and we can see slightly the images of background.The ST41was opaque and completely white and we cannot see any images through the film.Figure 4b shows the transmittance spectra of screen-printed TiO 2layers used in Figures 3and 4a.The P25layer transmitted 60%of incident light above 480nm wavelength and diffused the shorter wavelength effectively.Therefore,the P25layer was pale blue (Figure 4a).The transmittance of ST21increased linearly from 378to 820nm wavelength,and the transmittance at 820nm was half that of P25.ST41blocked the incident light below 600nm wavelength and let the incident light slightly through above that.For the comparison with homemade TiO 2,we added the data of transmission,which shows the higher transparency of the homemade TiO 2layer than those of commercially-available TiO 2powders.However,if 100%-anatase nanoparticles made by fumed-TiCl 4synthesis is available,more highly-transparent TiO 2layer can be fabricated.It has been reported that particles over 100nm can diffuse visible light effectively.12–14Hence,ST41(av.160nm)was able to diffuse visible light.This is the reason why the layer of ST41was white and opaque (Figure 4).On the other hand,the particle sizes of P25(av.21nm)and ST41(av.20nm)were close.Hence,the optical difference between layers of P25(transparent)and ST21(hazy)(Figure 4)arises from the aggregates and the roughness,acting as light-scattering centres (Figures 2and 3).The difference of morphologies was due to the synthetic variation:a liquid-phase synthesis for ST21and a gas-fumed synthesis forP25.Figure 3.Cross sections of nanocrystalline-TiO 2layers by surface-profiling method (Alfastep550):P25(a),ST21(b)andST41(c)Copyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pip608S.ITO ET AL.DSC Photovoltaics related with thickness of nanocrystalline-TiO 2electrodesIn order to fabricate DSCs,the TiO 2pastes were coated by screen-printing on FTO/glass substrates and assembled to DSC.For the high-efficiency DSC,therefore,we applied P25and ST41to transparent and light-scattering layers in double-layer photon-trapping system as reported,respectively.3–5Since the ST21layer was semi-transparent,we cannot expect the optical merit for applying the ST21layer to the double-layer photon-trapping system.Therefore,the ST21layer was used in DSC electrodes as a single layer.Figure 5shows the relationships between the screen-printing times and the thickness of nanocrystalline-TiO 2(P25and ST21)layers,which were used for DSC electrodes (Figures 5and 6).The ‘P25þST41’and ‘ST21’layers were double-layer and single-layer structures,respectively,as written in the previous paragraph.The thickness of ST41was fixed at 5Á7m m,which was obtained by the interception of y -axis.The linear relationship between the coating time and the thickness was confirmed.The thicknesses of one screen-print coating of P25and ST21were obtained as 1Á9m m and 2Á0m m,respectively.Each paste gave a thick layer over 17m m without cracking and peeling-up at the exterior;nanoscale cracks in the ST21layer were observed by SEM (see Figure 2d).Figure 6shows the photovoltaic-characteristic variations of open-circuit photo voltage (a,V OC ),short-circuit photo current density (b,J SC ),fill factor (c,FF)and conversion efficiency (d,h ).The V OC and FF decreased linearly with increasing thickness,but the changing ratios were just 10%and 2%,respectively (Figure 6a and c).On the other hand,J SC of P25-ST41and ST21increased by 30%and 50%,respectively (Figure 6b),which Figure 4.A picture (a)and transmittance spectra (b)of screen-printed nanocrystalline-TiO 2layers.The transmittance measurements were performed with cover glass plates which were attached on the surface of TiO 2layer,and the pores in nanocrystalline-TiO 2layers were filled with butoxyacetonitrile to decrease the light-scattering effect.The optical background for (b)was obtained by using the same FTO/glass substrate,butoxyacetonitrile and the cover glass plate Copyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipFABRICATION OF SCREEN-PRINTING PASTES 609projects the variation of h (Figure 6d).Resulting efficiencies of double-layer (P25-ST41)and single-layer (ST21)electrodes had peaks at 14and 17m m thickness of nanocrystalline layers (P25and ST21),respectively (Figure 6d).Figure 7shows photo I-V curves of best efficiency DSCs using P25-ST41and ST21.The photovoltaic characteristics were J SC ¼16Á25mA cm À2,V OC ¼779mV,FF ¼0Á730,and h ¼9Á24%with P25-ST41and J SC ¼15Á3mA cm À2,V OC ¼778mV ,FF ¼0Á733,and h ¼8Á75%with ST21.These efficiencies are the best results published ever with using commercially-available TiO 2powders.Figure 5.Relationship between number of coating times and thickness of screen-printed nanocrystalline-TiO 2layers of P25þST41and ST21.In P25þST41,the thickness of P25was varied and that of ST41was fixed at 5Á7m m by two-timesscreen printing for utilisation of photovoltaic measurements in Figures 6and7Figure 6.Photovoltaic-characteristics relationship with nanocrystalline (P25and ST21)-layer thickness of P25þST41(*)and ST21(&)electrodes:V OC (a),J SC (b),FF (c)and conversion efficiency (h )(d).The thickness of ST41was fixed at 5Á7m m for the light-scattering layer.The solid and doted lines were fitted to the average data of P25þST41and ST21,respectivelyCopyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pip610S.ITO ET AL.CONCLUSIONIn summary,this screen-printing technique enabled the fabrication of nanocrystalline layers over 17m m thickness from commercially-available TiO 2powders.The result of 9Á2%efficiency was lower than that from our homemade double-layered electrode (10–11%).4,5However,this report shows the best efficiencies using commercially-available TiO 2powders,which is very important for the world-wide market production of solar cells.Since P25and ST21contained rutile particles and large aggregates,respectively,the efficiencies were lower than 10%.If we can get more transparent electrodes using 100%-anatase nanoparticles made by fumed-TiCl 4synthesis,more highly efficient photovoltaic DSC can be fabricated.We believe that this report can be of great help for the DSC researchers.The results of this study imply that using TiO 2powders of a large commercial batch instead of TiO 2particles of homemade small different batches result in a more reproducible cell efficiency.This methodological investigation can contribute not only to the research of DSC,but also to various applications of industrial and scientific works in several fields as suggested in the introduction.AcknowledgementsWe acknowledge financial support of this work by the Swiss Science Foundation and Swiss Federal Office for Energy (OFEN).Peter Chen thanks the Taiwan Merit Scholarships Program (TMS-094-2A-026).The SEM-image works were carried out in the CIME of EPFL.REFERENCES1.O’Regan B,Gra¨tzel M.A low cost,high-efficiency solar cell based on dye-sensitized colloidal TiO 2films.Nature (London)1991;353:737–739.2.Gra¨tzel M.Photoelectrochemical cells.Nature (London)2001;414:338–344.3.Wang P,Zakeeruddin SM,Comte P,Charvet R,Humphry-Baker R,Gratzel M.Enhance the performance of dye-sensitized solar cells by co-grafting amphiphilic sensitizer and hexadecylmalonic acid on TiO 2nanocrystals.Journal of Physical Chemistry B 2003;107:14336–14341.4.Ito S,Nazeeruddin MK,Liska P,Comte P,Charvet R,Pe´chy P,Jirousek M,Kay A,Zakeeruddin SM,Gratzel M.Photovoltaic characterization of dye-sensitized solar cells:effect of device masking on conversion efficiency.Progress in Photovoltaics 2006;14:589–601.Figure 7.Photo I-V curves of best-efficiency dye-sensitised solar cells using nanocrystalline-TiO 2electrodes fabricated from commercially-available nanocrystalline-TiO 2powders (P25þST41,h ¼9Á24%;ST21,h ¼8Á75%)under100mW cm À2AM 1Á5irradiationCopyright #2007John Wiley &Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pipFABRICATION OF SCREEN-PRINTING PASTES 611612S.ITO ET AL.5.Nazeeruddin Md K,De Angelis F,Fantacci S,Selloni A,Viscardi G,Liska P,Ito S,Takeru B,Gra¨tzel binedexperimental and DFT-TDDFT computational study of photoelectrochemical cell ruthenium sensitizers.Journal of the American Chemical Society2005;127:16835–16847.6.Tsoukleris DS,Arabatzis IM,Chatzivasiloglou E,Kontos AI,Belessi V,Bernard MC,Falaras P.2-Ethyl-1-hexanol basedscreen-printed titania thinfilms for dye-sensitized solar cells.Solar Energy2005;79:422–430.7.Zhang D,Ito S,Wada Y,Kitamura T,Yanagida S.Nanocrystalline TiO2electrodes prepared by water-medium screenprinting technique.Chemistry Letters2001;30:1042–1043.8.Gupta TK,Cirignano LJ,Shah KS,Moy LP,Kelly DJ,Squillante MR,Entine G,Smestad GP.Screen-printeddye-sensitized large area nanocrystalline solar cell.Material Research Society Symposium Proceedings2000;581: 653–658.9.Ma T,Kida T,Akiyama M,Inoue K,Tsunematsu S,Yao K,Noma H,Abe E.Preparation and properties ofnanostructured TiO2electrode by a polymer organic-medium screen-printing technique.Electrochemistry Communi-cations2003;5:369–372.10.Nazeeruddin MK,Zakeeruddin SM,Humphry-Baker R,Jirousek M,Liska P,Vlachopoulos N,Shklover V,Fischer CH,Gra¨tzel M.Acid-base equilibria of(2,2’-Bipyridyl-4,4’-dicarboxylic acid)ruthenium(II)complexes and the effect of protonation on charge-transfer sensitization of nanocrystalline titania.Inorganic Chemistry1999;38:6298–6305. 11.Bonhoˆte P,Dias AP,Armand M,Papageorgiou N,Kalyanasundaram K,Gra¨tzel M.Hydrophobic,highly conductiveambient-temperature molten salts.Inorganic Chemistry1996;35:1168–1178.12.Rothenberger G,Comte P,Gra¨tzel M.A contribution to the optical design of dye-sensitized nanocrystalline solar cells.Solar Energy Materials and Solar Cells1999;58:321–336.13.Tachibana Y,Hara K,Sayama K,Arakawa H.Quantitative analysis of light-harvesting efficiency and electron-transferyield in ruthenium-dye-sensitized nanocrystalline TiO2solar cells.Chemistry of Materials2002;14:2527–2535. 14.Ito S,Yoshida S,Watanabe T.Preparation of Colloidal Anatase TiO2Secondary Submicroparticles by HydrothermalSol-Gel Method.Chemistry Letters2000;29:70–71.Copyright#2007John Wiley&Sons,Ltd.Prog.Photovolt:Res.Appl.2007;15:603–612DOI:10.1002/pip。

光伏建筑设计规范

光伏建筑设计规范
13.4
中、小型光伏系统不具备接入公共电网条件时,经论证同意
光伏系统与公共电网之间应设隔离装置,并应符合以下要求
1光伏系统在供电负荷与并网逆变器之间和公共电网与负荷之间应设置隔离装置,包括隔离开关和断路器,并应具有明显断开点指示及断零功能(断零功能仅对0。4KV及以下低压系统适用);
2光伏系统在并网处应设置并网专用低压开关箱(柜),并设置专用标识和“警告”、“双电源”等提示性文字和符号;
光伏电池
将太阳辐射能直接转换成电能的一种器件
光伏组件
由若干光伏电池进行内部联结并封装、能输出直流电流、最基本的太阳电池单元,也称太阳电池组件。
光伏方阵
由若干光伏组件或光伏构件通过机械及电气方式组装成型、并安装在支撑装置上的直流发电单元。
光伏组件倾角
光伏组件所在平面与水平面的夹角。
并网光伏系统
与公共电网联接的光伏系统。
本导则的主要技术内容为:光伏系统设计、光伏与建筑一体化设计、光伏系统安装和调试、环保及卫生安全消防、工程质量验收、运行管理与维护。
本导则由杭州市建设委员会负责管理,由浙江省建筑科学设计研究院有限公司负责具体技术内容的解释.在执行过程中如有修改或补充之处,请将意见或有关资料寄送浙江省建筑科学设计研究院有限公司(地址:杭州市文二路28号,邮编:310012,电子邮箱:zjjkbipvdz@163。com),以便修订时参考。
1并网逆变器应具备自动运行和停止功能、最大功率跟踪控制功能和防止孤岛效应功能;
2逆流型并网逆变器应具备自动电压调整功能;
3不带工频隔离变压器的并网逆变器应具备直流检测功能;
4无隔离变压器的并网逆变器应具备直流接地检测功能;
5并网逆变器应具有并网保护装置,与电力系统具备相同的电压、相数、相位、频率及接线方式;

应用物理学SCI期刊排名

应用物理学SCI期刊排名

49
Plasma Processes and Polymers
50
IEEE Journal of Photovoltaics
51
Nano Futures
52
Nano Convergence
53 IEEE TRANSACTIONS ON ELECTRON DEVICES
54
VACUUM
55
IEEE Photonics Journal
0.158460 0.100240 0.484600 0.005670 0.168910 0.011250 0.214130 0.115660 0.005780 0.111140 0.278940 0.016260 0.002060 0.004520 0.002750 0.038880 0.008840 0.008420 0.007720 0.001310 0.104500 0.034330 0.207430 0.048100 0.017430 0.005480 0.132300 0.002640 0.009040 0.015030 0.004690 0.033740 0.012980 0.032660 0.001450 0.001190 0.184670 0.021210 0.329400 0.045520 0.018210 0.012640 0.049990 0.045890 0.016850 0.013010 0.031700 0.014070
30
QUANTUM ELECTRONICS
31
APL Photonics
32
Physical Review Applied
33
APL Materials
34
SURFACE & COATINGS TECHNOLOGY

Bidirectional reflectance distribution function

Bidirectional reflectance distribution function

Bidirectional reflectance distributionfunction Diagram showing vectors used to define the BRDF.All vectors areunit length.ωi points toward the light source.ωr points towardthe viewer(camera).n is the surface normal.The bidirectional reflectance distribution function(BRDF;f r(ωi,ωr))is a function of four real variablesthat defines how light is reflected at an opaque surface.It is employed both in the optics of real-world light,incomputer graphics algorithms,and in computer vision al-gorithms.The function takes an incoming light direction,ωi,and outgoing direction,ωr(taken in a coordinate sys-tem where the surface normal n lies along the z-axis),andreturns the ratio of reflected radiance exiting alongωr tothe irradiance incident on the surface from directionωi.Each directionωis itself parameterized by azimuth angleϕand zenith angleθ,therefore the BRDF as a whole isa function of4variables.The BRDF has units sr−1,withsteradians(sr)being a unit of solid angle.1DefinitionThe BRDF wasfirst defined by Fred Nicodemus around1965.[1]The definition is:f r(ωi,ωr)=d L r(ωr)d E i(ωi)=d L r(ωr)L i(ωi)cosθi dωiwhere L is radiance,or power per unit solid-angle-in-the-direction-of-a-ray per unit projected-area-perpendicular-to-the-ray,E is irradiance,or power per unit surface area, andθi is the angle betweenωi and the surface normal,n .The index i indicates incident light,whereas the index r indicates reflected light.The reason the function is defined as a quotient of two differentials and not directly as a quotient between the undifferentiated quantities,is because other irradiatinglight than d E i(ωi),which are of no interest for f r(ωi,ωr) ,might illuminate the surface which would unintention-ally affect L r(ωr),whereas d L r(ωr)is only affected by d E i(ωi).2Related functionsThe Spatially Varying Bidirectional Reflectance Dis-tribution Function(SVBRDF)is a6-dimensional func-tion,f r(ωi,ωr,x),where x describes a2D location over an object’s surface.The Bidirectional Texture Function(BTF)is appro-priate for modeling non-flat surfaces,and has the same parameterization as the SVBRDF;however in contrast, the BTF includes non-local scattering effects like shad-owing,masking,interreflections or subsurface scattering. The functions defined by the BTF at each point on the surface are thus called Apparent BRDFs.The Bidirectional Surface Scattering Reflectance Dis-tribution Function(BSSRDF),is a further generalized 8-dimensional function S(x i,ωi,x r,ωr)in which light entering the surface may scatter internally and exit at an-other location.In all these cases,the dependence on the wavelength of light has been ignored and binned into RGB channels. In reality,the BRDF is wavelength dependent,and to account for effects such as iridescence or luminescence the dependence on wavelength must be made explicit: f r(λi,ωi,λr,ωr).3Physically based BRDFsPhysically realistic BRDFs have additional properties,[2] including,•positivity:f r(ωi,ωr)≥0•obeying Helmholtz reciprocity:f r(ωi,ωr)=f r(ωr,ωi)•conserving energy:∀ωr,∫Ωf r(ωi,ωr)cosθi dωi≤1127SEE ALSO4ApplicationsThe BRDF is a fundamental radiometric concept,and ac-cordingly is used in computer graphics for photorealistic rendering of synthetic scenes(see the rendering equa-tion),as well as in computer vision for many inverse prob-lems such as object recognition.BRDF has also been used for modeling light trapping in solar cells(ing the OPTOS formalism)or low concentration solar photo-voltaic systems.[3][4]In the context of satellite remote sensing,NASA uses a BRDF model to characterise surface anisotropy.For a given land area,the BRDF is established based on se-lected multiangular observations of surface reflectance. While single observations depend on view geometry and solar angle,the MODIS BRDF/Albedo product describes intrinsic surface properties in several spectral bands,at a resolution of500meters.[5]The BRDF/Albedo product can be used to model surface albedo depending on atmo-spheric scattering.5ModelsBRDFs can be measured directly from real objects using calibrated cameras and lightsources;[6]however,many phenomenological and analytic models have been pro-posed including the Lambertian reflectance model fre-quently assumed in computer graphics.Some useful fea-tures of recent models include:•accommodating anisotropic reflection •editable using a small number of intuitive parame-ters•accounting for Fresnel effects at grazing angles •being well-suited to Monte Carlo methods.W.Matusik et al.found that interpolating between mea-sured samples produced realistic results and was easy to understand.[7]5.1Some examples•Lambertian model,representing perfectly diffuse (matte)surfaces by a constant BRDF.•Lommel–Seeliger,lunar and Martian reflection.•Phong reflectance model,a phenomenological model akin to plastic-like specularity.[8]•Blinn–Phong model,resembling Phong,but allow-ing for certain quantities to be interpolated,reducing computational overhead.[9]•Torrance–Sparrow model,a general model repre-senting surfaces as distributions of perfectly spec-ular microfacets.[10]•Cook–Torrance model,a specular-microfacet model(Torrance–Sparrow)accounting for wave-length and thus color shifting.[11]•Ward model,a specular-microfacet model with an elliptical-Gaussian distribution function dependent on surface tangent orientation(in addition to surface normal).[12]•Oren–Nayar model,a“directed-diffuse”microfacet model,with perfectly diffuse(rather than specular) microfacets.[13]•Ashikhmin-Shirley model,allowing for anisotropic reflectance,along with a diffuse substrate under a specular surface.[14]•HTSG(He,Torrance,Sillion,Greenberg),a compre-hensive physically based model.[15]•Fitted Lafortune model,a generalization of Phong with multiple specular lobes,and intended for para-metricfits of measured data.[16]•Lebedev model for analytical-grid BRDF approximation.[17]6AcquisitionTraditionally,BRDF measurements were taken for one specific lighting and viewing direction at a time using gonioreflectometers.Unfortunately,using such a device to densely measure the BRDF is very time consuming. One of thefirst improvements on these techniques used a half-silvered mirror and a digital camera to take many BRDF samples of a planar target at once.Since this work, many researchers have developed other devices for effi-ciently acquiring BRDFs from real world samples,and it remains an active area of research.There is an alternative way to measure BRDF based on HDR images.The standard algorithm is to measure the BRDF point cloud from images and optimize it by one of the BRDF models.[18]7See also•Albedo•BSDF•Gonioreflectometer•Opposition spike•Photometry(astronomy)3•Radiometry•Reflectance•Schlick’s approximation•Specular highlight8References[1]Nicodemus,Fred(1965).“Directional reflectance andemissivity of an opaque surface”(abstract).Applied Op-tics.4(7):767–775.Bibcode:1965ApOpt...4..767N.doi:10.1364/AO.4.000767.[2]Duvenhage,Bernardt(2013).“Numerical verification ofbidirectional reflectance distribution functions for physi-cal plausibility”.Proceedings of the South African Insti-tute for Computer Scientists and Information Technologists Conference.pp.200–208.[3]Andrews,Rob W.;Pollard,Andrew;Pearce,JoshuaM.,"Photovoltaic system performance enhancement with non-tracking planar concentrators:Experimental results and BRDF based modelling,”Photovoltaic Specialists Conference(PVSC),2013IEEE39th,pp.0229,0234,16–21June2013.doi:10.1109/PVSC.2013.6744136 [4]Andrews,R.W.;Pollard,A.;Pearce,J.M.,“PhotovoltaicSystem Performance Enhancement With Nontracking Planar Concentrators:Experimental Results and Bidirec-tional Reflectance Function(BDRF)-Based Modeling,”IEEE Journal of Photovoltaics5(6),pp.1626-1635(2015).DOI:10.1109/JPHOTOV.2015.2478064[5]“BRDF/Albedo”.NASA,Goddard Space Flight Center.Retrieved March9,2017.[6]Rusinkiewicz,S.“A Survey of BRDF Representation forComputer Graphics”.Retrieved2007-09-05.[7]Wojciech Matusik,Hanspeter Pfister,Matt Brand,andLeonard McMillan.A Data-Driven Reflectance Model.ACM Transactions on Graphics.22(3)2002.[8] B.T.Phong,Illumination for computer generated pic-tures,Communications of ACM18(1975),no.6,311–317.[9]James F.Blinn(1977).“Models of light reflection forcomputer synthesized pictures”.Proc.4th annual con-ference on computer graphics and interactive techniques: 192.doi:10.1145/563858.563893.[10]K.Torrance and E.Sparrow.Theory for Off-Specular Re-flection from Roughened Surfaces.J.Optical Soc.Amer-ica,vol.57.1967.pp.1105–1114.[11]R.Cook and K.Torrance.“A reflectance model for com-puter graphics”.Computer Graphics(SIGGRAPH'81 Proceedings),Vol.15,No.3,July1981,pp.301–316.[12]Ward,Gregory J.(1992).“Measuring and modelinganisotropic reflection”.Proceedings of SIGGRAPH.pp.265–272.doi:10.1145/133994.134078.[13]S.K.Nayar and M.Oren,"Generalization of the Lamber-tian Model and Implications for Machine Vision".Inter-national Journal on Computer Vision,Vol.14,No.3,pp.227–251,Apr,1995[14]Michael Ashikhmin,Peter Shirley,An Anisotropic PhongBRDF Model,Journal of Graphics Tools2000[15]X.He,K.Torrance,F.Sillon,and D.Greenberg,A com-prehensive physical model for light reflection,Computer Graphics25(1991),no.Annual Conference Series,175–186.[16] fortune,S.Foo,K.Torrance,and D.Greenberg,Non-linear approximation of reflectance functions.In Turner Whitted,editor,SIGGRAPH97Conference Pro-ceedings,Annual Conference Series,pp.117–126.ACM SIGGRAPH,Addison Wesley,August1997.[17]Ilyin A.,Lebedev A.,Sinyavsky V.,Ignatenko,A.,Image-based modelling of material reflective properties offlat objects(In Russian).In:GraphiCon'2009.;2009.p.198-201.[18]BRDFRecon project9Further reading•Lubin,Dan;Robert Massom(2006-02-10).Polar Remote Sensing.Volume I:Atmosphere and Oceans (1st ed.).Springer.p.756.ISBN3-540-43097-0.•Matt,Pharr;Greg Humphreys(2004).Physically Based Rendering(1st ed.).Morgan Kauffmann.p.1019.ISBN0-12-553180-X.•Schaepman-Strub,G.;M.E.Schaepman;T.H.Painter;S.Dangel;J.V.Martonchik(2006-07-15).“Reflectance quantities in optical re-mote sensing:definitions and case studies”.Re-mote Sensing of Environment.103(1):27–42.doi:10.1016/j.rse.2006.03.002.Retrieved2015-11-01.•An intuitive introduction to the concept of reflection model and BRDF.410TEXT AND IMAGE SOURCES,CONTRIBUTORS,AND LICENSES 10Text and image sources,contributors,and licenses10.1Text•Bidirectional reflectance distribution function Source:https:///wiki/Bidirectional_reflectance_distribution_function?oldid=778971918Contributors:Meekohi,Charles Matthews,Ldo,Altenmann,DocWatson42,Richie,Rich Farmbrough,Hooperbloob, Waldir,Srleffler,Kri,Jaraalbe,Dhwoow,Banus,Deuar,SmackBot,KYN,Chris the speller,Pietaster,Drewnoakes,Tsca.bot,Ieth wk, Jurohi,Dicklyon,Plewis,Barticus88,Escarbot,Magioladitis,Cdecoro,Pruthvi.Vallabh,Antarktis~enwiki,Selinger,Blueclaw,Dhatfield, Svick,Rilak,Jakarr,Swindbot,Addbot,DOI bot,Zacao,Legobot,Luckas-bot,Yobot,AnomieBOT,Rubinbot,Citation bot,Martin Kraus, Pmlineditor,Ivan Shmakov,Tom.Reding,Lanser1989,Jnnewn,Git2010,Helpful Pixie Bot,Bibcode Bot,Eheitz,BG19bot,YFdyh-bot,So-ravux,Mark viking,Ekips39,Tentinator,Stack Overflow,Naeschdy,Monkbot,Gondi56,AkhilKallepalli1290,Buntuhug,Fmadd,Blaesi, L8ManeValidus,Petra Sieber(SLU)and Anonymous:4510.2Images•File:5-cell.gif Source:https:///wikipedia/commons/d/d8/5-cell.gif License:Public domain Contributors:Transferred from en.wikipedia to Commons.Original artist:JasonHise at English Wikipedia•File:BRDF_Diagram.svg Source:https:///wikipedia/commons/e/ed/BRDF_Diagram.svg License:CC BY-SA3.0 Contributors:•BRDF_Diagram.png Original artist:BRDF_Diagram.png:Meekohi10.3Content license•Creative Commons Attribution-Share Alike3.0。

薄层晶体硅双面陷光结构的制备及其性能研究

薄层晶体硅双面陷光结构的制备及其性能研究

薄层晶体硅双面陷光结构的制备及其性能研究戴恩琦;张帅;吕文辉【摘要】Silicon nanostructure arrays were prepared on the front and back surfaces of thin-layer crystal silicon by using a metal-assisted silicon chemical etching method.The light trapping performance of the nano-textured thin-layer crystal silicon was characterized by combining its reflection spectra and transmission spectra.It demonstrated that the nano-textured thin-layer crystal silicon exhibit enhanced light trapping performance as compared with the performance of planar surface or pyramid structure.The nano-textured thin-layer crystal silicon can absorb about 93.4% of AM 1.5 Gphotons in the ~70μm range.The results provide a way to solve the light lost problem in thin-layer crystal silicon solar cells.%采用金属辅助硅化学刻蚀法, 在薄层晶体硅片前后表面分别制备硅纳米陷光结构,并表征其增强薄层晶体硅对太阳光子吸收的性能.对比研究无表面织构、双面金字塔织构、双面硅纳米织构的薄层晶体硅的漫反射光谱与透射光谱, 结果表明, 双面硅纳米织构的薄层晶体硅具有卓越的光吸收性能, ~70μm厚度的薄层晶体硅片能够吸收93.4%的AM1.5G太阳光子.该研究结果为解决晶硅太阳电池中的光学损失问题提供了一种可供选择的陷光结构.【期刊名称】《湖州师范学院学报》【年(卷),期】2019(041)002【总页数】4页(P40-43)【关键词】薄层晶体硅;表面织构;光诱捕性能【作者】戴恩琦;张帅;吕文辉【作者单位】湖州师范学院理学院,浙江湖州 313000;湖州师范学院理学院,浙江湖州 313000;湖州师范学院理学院,浙江湖州 313000【正文语种】中文【中图分类】TM914.40 引言晶硅太阳电池发电具有清洁、可再生、安全稳定等优点,是一种可持续发展的能源供给方式.目前晶硅太阳电池的发电成本高于传统火力发电成本,严重阻碍了其广泛使用,因此需有效地降低发电成本,才能推动晶硅太阳电池发电产业的发展.当前,学术界和产业界均积极研究提高晶硅太阳电池的光电转换效率[1-3],以降低发电成本.从整个晶硅太阳电池的成本构成分析表明,180 μm厚的晶体硅原料约占整个电池成本的60%~70%.若将晶体硅太阳电池的厚度降低,构成薄层晶硅太阳电池,则其成本将会有效地降低.但晶体硅对长波太阳光子(850~1 100 nm)的吸收系数小[4,5],厚度降低后将不能充分吸收该谱段的太阳光子,造成可观的光学损失,因此如何使薄层晶体硅有效地捕获和吸收带隙能量之上(300~1 100 nm)的太阳光子是一个重要的研究课题.针对如何使薄层晶体硅有效地捕获和吸收太阳光子,国内外科技工作者设计了各种陷光结构,以有效增加长波光子在薄层晶体硅中的传输路径,实现高效的捕获和吸收.如在晶体硅前表面和背表面分别制作布拉格抗反射和增反射结构[6]、利用等离基元调控光场分布法在晶体硅前表面制作金属纳米结构[7]等.硅纳米结构的几何尺寸与太阳光波长接近,能够衍射和散射太阳光,从而减少光反射损失及调控光场分布.这种新型的陷光结构应用于薄层晶体硅太阳电池值得研究.本文以~70 μm厚的薄层晶体硅作为衬底,通过金属辅助硅化学刻蚀法[8-11],在其前后表面制备硅纳米结构,以诱捕太阳光子.通过测试双面硅纳米织构的薄层晶体硅的漫反射与透射光谱,表征和评价双面硅纳米织构增强薄层晶体硅对太阳光子吸收的性能.研究结果表明,相对于无表面织构和传统金字塔织构,硅纳米织构具有优异的光诱捕性能,能有效地增强薄层晶体硅的光吸收.1 实验采用各向同性混酸腐蚀工艺[12-14]减薄晶体硅片:室温下将200 μm厚度的晶体硅片放入由硝酸、氢氟酸、磷酸及去离子水组成的混酸溶液中,腐蚀减薄获得~70 μm厚度的薄层晶体硅片.该混酸溶液中的硝酸主要起到氧化作用,将硅氧化成二氧化硅;溶液中的氢氟酸又将二氧化硅腐蚀,生成溶于水的六氟硅酸.上述反应自发循环进行,最终达到减薄晶体硅片的效果.其中,磷酸作为一种缓冲剂,能够调控腐蚀溶液的pH值以及腐蚀减薄的速率,提高硅片腐蚀表面的光滑平整度,以获得更好的减薄效果.以薄层晶体硅为原料,采用标准的各向异性碱腐蚀工艺[15],在薄层晶体硅前后表面制备金字塔结构.首先,将薄层晶体硅片样品放入氢氟酸溶液中浸泡去除表面氧化层.然后,将样品放入由氢氧化钾以及少量异丙醇组成的腐蚀溶液中,溶液的温度控制在80 ℃,从而在样品前后表面各向异性刻蚀制备金字塔结构.最后,将制备好的金字塔结构样品放入25%的硝酸溶液中浸泡,去除其表面的残留碱液,获得双面金字塔织构的薄层晶体硅样品.以薄层晶体硅为原料,采用金属辅助硅化学刻蚀法[11],在薄层晶体硅前后表面制备硅纳米结构.首先,将薄层晶体硅片样品浸入由硝酸银、氢氟酸、去离子水组成的混合溶液中,在样品的前后表面淀积金属银颗粒催化层.然后,将表面覆盖有金属银催化层的样品放入由双氧水、氢氟酸、去离子水组成的混合溶液中,从而在样品前后表面化学刻蚀形成硅纳米结构.最后,将制作好的硅纳米结构样品放入50%的硝酸溶液中浸泡,去除金属银催化剂,获得双面硅纳米织构的薄层晶体硅样品. 采用扫描电子显微镜(SEM)表征薄层晶体硅样品的厚度,以及制备得到的双面金字塔织构和双面硅纳米织构的形貌.采用紫外-可见-近红外分光光度计(含积分球附件)测试具有双面陷光结构的薄层晶体硅样品的漫反射和透射光谱.结合AM1.5G太阳光谱积分获得不同表面织构的薄层晶体硅的反射损失比、透射损失比及有效光吸收比,对比评价无表面织构、双面金字塔织构、双面硅纳米织构增强薄层晶体硅对太阳光子吸收的性能.2 结果与讨论本研究采用扫描电子显微镜(SEM)表征薄层晶体硅的厚度及制备获得的两种陷光结构的形貌,所得结果如图1所示.图1(a)为双面金字塔结构薄层晶体硅样品的SEM 形貌照片.图中显示薄层晶体硅的厚度约为70 μm,并在其前后表面分布有金字塔结构,金字塔结构的高度约为5 μm.右上角插图为该金字塔织构表面的SEM形貌照片,由图中可以看出金字塔结构为随机分布且覆盖均匀,其底边长度约为7 μm.图1(b)为双面硅纳米织构的薄层晶体硅样品的SEM形貌照片.图中显示薄层晶体硅的厚度约为70 μm,并在其前后表面分布有垂直的硅纳米结构,硅纳米结构的竖直高度约为1 μm.右上角插图为该硅纳米织构表面的SEM形貌照片,图片表明硅纳米结构为多孔结构,其孔径和孔壁尺寸在100~400 nm之间,是一种亚波长尺寸的纳米结构.这种亚波长结构能够衍射和散射太阳光,从而减少光反射损失及调控光场分布.Fig.1 The SEM photographs of different light trapping structures on the thin-layer crystal silicon为了表征双面陷光结构,增强薄层晶体硅诱捕和吸收太阳光子的性能,本研究分别测试了无表面织构、双面金字塔织构、双面硅纳米织构的薄层晶体硅样品的漫反射和透射光谱,测试结果如图2所示.图2(a)为测得的漫反射谱,结果显示双面硅纳米织构的薄层晶体硅具有较低的光反射率,其中,在300~950 nm光谱范围内,每一波长对应的反射率均小于2%,并且在300~1 100 nm宽光谱范围内,双面硅纳米织构的薄层晶体硅的光反射率均低于无表面织构及双面金字塔织构的薄层晶体硅的光反射率.该结果表明,硅纳米结构能够有效地降低薄层晶体硅的前表面光反射损失.图2(b)为测得的漫透射谱.图中显示在300~850 nm光谱范围内,三种双面陷光结构的薄层晶体硅几乎都没有透射.但在850~1 100 nm光谱范围内,相比于无表面织构和双面硅纳米织构,双面金字塔织构的薄层晶体硅样品光透射率要更低.其主要原因可能是薄层晶体硅背表面上的金字塔织构表现出较好的背面长波反射性能,将未吸收的长波太阳光子内反射回晶体硅,从而产生优异的抗透射作用.另外,无表面织构与双面硅纳米织构相比,双面硅纳米织构的光透射率更低,表明硅纳米结构也能够有效地降低薄层晶体硅的背表面光透射损失.结合该研究结果,更理想的陷光结构应为:前表面采用硅纳米结构以减少光反射损失,背表面为金字塔结构以减少光透射损失.Fig.2 The reflection spectra and transmission spectra of thin-layer crystal silicon with different double-sided light trapping structures为进一步评估双面陷光结构,增强薄层晶体硅对太阳光子捕获和吸收的性能,结合标准的AM1.5G的太阳光谱计算双面陷光织构薄层晶体硅的有效吸收比ηA.在300~1 100 nm的光谱范围内,AM1.5G太阳光谱的ηA可表示为:(1)其中:ηR为有效反射损失比;ηT为有效透射损失比;λ为光波波长;R(λ)为反射率;T(λ)为透射率;IAM1.5G(λ)为标准的AM1.5G的太阳光谱强度;h为普朗克常数;c为光速.计算结果如表1所示.在300~1 100 nm的光谱范围内,双面硅纳米织构的薄层晶体硅对AM1.5G太阳光子的吸收比高于无表面织构、双面金字塔织构的光子吸收比.结果表明,双面硅纳米织构具有优异的光诱捕性能,能够大大增强薄层晶体硅对太阳光子的捕获和吸收.表1 不同双面陷光结构薄层晶体硅对太阳光的有效吸收比 Tab.1 The absorption ratio of sun-light in the thin-layer crystal silicon with different double-sided light trapping structuresLight trapping structureplanar surfacepyramid structurenanostructureAbsorption ratio/%60.688.293.43 结论采用金属辅助硅化学刻蚀法和传统碱制绒法在~70 μm厚的薄层晶体硅上分别成功核对制备了双面硅纳米和双面金字塔结构.通过测试和分析薄层晶体硅无表面织构、双面金字塔织构和双面硅纳米织构的薄层晶体硅的漫反射光谱和透射光谱,证实了双面硅纳米织构的薄层晶体硅具有卓越的光吸收性能, ~70 μm厚度的薄层晶体硅片能够吸收93.4%的AM1.5G太阳光子.该研究结果为解决晶硅太阳电池中的光学损失问题提供了一种可供选择的陷光结构.参考文献:【相关文献】[1]SCHULTZ O,GLUNZ S W,RIEPE S,et al.High-efficiency solar cells on phosphorus gettered multicrystalline silicon substrates[J].Progress in Photovoltaics:Research and Applications,2006,14(8):711-719.[2]KIM K R,KIM T H,PARK H A,et al.UV laser direct texturing for high efficiency multicrystalline silicon solar cell[J].Applied Surface Science,2013,264:404-409.[3]吕文辉,陆波,龚熠,等.多晶硅太阳电池背表面刻蚀提升其性能的产线工艺研究[J].光电子·激光,2016,27(6):606-612.[4]GREEN M A.Self-consistent optical parameters of intrinsic silicon at 300 K including temperature coefficients[J].Solar Energy Materials and Solar Cells,2008,92(11):1 305-1 310.[5]SCHINKE C,PEEST P C,SCHMIDT J,et al.Uncertainty analysis for the coefficient of band-to-band absorption of crystalline silicon[J].AIP Advances,2015,5(6):167-168.[6]周舟,周健,孙晓玮,等.薄膜太阳能电池异型布拉格背反射结构设计与制作[J].光学学报,2011,31(7):283-287.[7]明海,王小蕾,王沛,等.表面等离激元的调控研究与应用[J].科学通报,2010,55(21):2 068-2 077.[8]PENG K Q,LEE S T.Silicon nanowires for photovoltaic solar energyconversion[J].Advanced Materials,2010,23(2):198-215.[9]HUANG Z P,GETER N,WERNER P,et al.Metal-assisted chemical etching of silicon:a review[J].Advanced Materials,2011,23(2):285-308.[10]BACKES A,SCHMID U.Impact of doping level on the metal assisted chemical etching of p-type silicon[J].Sensors & Actuators:B Chemical,2014,193:883-887.[11]戴恩琦,王欢欢,谢汝平,等.晶体硅表面纳米孔减反光结构的制备及其性能表征[J].光电子·激光,2017,28(12):1 325-1 330.[12]STEINERT M,ACKER J,OSWALD S,et al.Study on the mechanism of silicon etching in HNO3-rich HF/HNO3mixtures[J].J Phys Chem C,2007,111(5):2 133-2 140.[13]STEINERT M,ACKER J,KRAUSE M,et al.Reactive species generated during wet chemical etching of silicon in HF/HNO3mixtures[J].J Phys Chem B,2006,110(23):11 377-11 382. [14]ACKER J,RIETIG A,STEINERT M,et al.Electron balance for the oxidation of silicon during the wet chemical etching in HF/HNO3mixtures[J].J Phys Chem C,2012,116(38):20 380-20 388.[15]SEIDEL H,CSEPREGI L,HEUBERGER A,et al.Anisotropic etching of crystalline silicon in alkaline solutions[J].J Electrochem Soc,1990,137:3 612-3 626.。

光伏单晶硅棒生产工艺流程

光伏单晶硅棒生产工艺流程

光伏单晶硅棒生产工艺流程英文回答:The production process of monocrystalline silicon rods for photovoltaics involves several steps. I will explain each step in detail.1. Seed crystal production: The first step is to produce the seed crystals. These are small pieces of monocrystalline silicon that will act as the starting point for the growth of the silicon rods. The seed crystals are carefully grown in a controlled environment to ensure their quality and purity.2. Silicon purification: The next step is to purify the silicon. Impurities are removed from the silicon using various purification techniques such as zone refining or chemical vapor deposition. This process ensures that the silicon used for the rods is of high quality and has a low level of impurities.3. Silicon melting: Once the silicon is purified, it is melted in a high-temperature furnace. The molten silicon is then carefully cooled to form a solid ingot. This ingotwill serve as the source material for the silicon rods.4. Ingot slicing: The solid ingot is sliced into thin wafers using a wire saw or a diamond blade. These wafers are then further processed to remove any defects or impurities.5. Wafer polishing: The sliced wafers undergo a polishing process to achieve a smooth and flat surface. This is important for the subsequent steps in the production process.6. Wafer cleaning: The polished wafers are thoroughly cleaned to remove any particles or contaminants. This ensures that the wafers are ready for the next step.7. Doping: Doping is the process of introducing impurities into the silicon wafers to create the desiredelectrical properties. This step involves the use of dopant materials such as boron or phosphorus.8. Photolithography: Photolithography is used to create the pattern on the wafers. A layer of photoresist isapplied to the wafers, and then a mask is used to exposethe desired pattern. The exposed areas are then etched away, leaving the desired pattern on the wafers.9. Metallization: The wafers are then coated with metal contacts, usually made of silver or aluminum. Thesecontacts allow for the extraction of electrical currentfrom the solar cells.10. Cell testing: The finished solar cells are testedto ensure their performance and quality. This involves measuring parameters such as efficiency, voltage, and current.11. Module assembly: Finally, the solar cells are assembled into modules. These modules are then ready for installation and use in photovoltaic systems.中文回答:光伏单晶硅棒的生产工艺流程包括几个步骤。

运用初中物理知识做发明的例子

运用初中物理知识做发明的例子

运用初中物理知识做发明的例子英文版In middle school, students are introduced to the basic principles of physics. These principles can be applied in various ways, including in the creation of inventions. One example of using middle school physics knowledge to invent something is the creation of a solar-powered phone charger.The concept behind a solar-powered phone charger is simple: harnessing the energy from the sun to charge a mobile device. This invention utilizes the principles of photovoltaics, which is the conversion of light into electricity. By placing solar panels on a portable charger, users can charge their phones on the go without relying on traditional electricity sources.To create a solar-powered phone charger, one must first understand the basic physics of how solar panels work. Solar panels are made up of photovoltaic cells, which contain layers of semiconductor materials. When sunlight hits these cells, it excites the electrons in the semiconductor, creating an electric current. This current is then stored in a battery or used to directly charge a device.By applying their knowledge of photovoltaics and electricity, middle school students can design and build their own solar-powered phone charger. This hands-on project not only reinforces their understanding of physics principles but also allows them to see the practical applications of their learning.In conclusion, the invention of a solar-powered phone charger is a great example of how middle school physics knowledge can be applied in real-world scenarios. By understanding the principles of photovoltaics and electricity, students can create innovative solutions to everyday problems.中文版在中学阶段,学生们被介绍了物理的基本原理。

能量转换与存储原理教学资料 multijunction_cells

能量转换与存储原理教学资料 multijunction_cells

Common 3-cell structure
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Efficiency for various top and middle cells when the substrate is germanium
Baur, C. et.al., Journal of Solar Energy Engineering, 2007
Areal defect density is 8×106cm-2 Higher voltage upper sub-cell uses larger part of solar
spectrum More freedom to choose upper and middle ceRll.Rm.Kiangteetr.aila, Alsppl. Phys. Lett. 90, 2007
Current Matching
Individually Optimized Cells
Current-matched cells for MJSC
Synopsys, Inc., February 2009
Current Matching
•Current limited by lowest-current subcell •Total VOC is ~equal to sum of subcell VOC’s
2005. Conference Record of the Thirty-first IEEE, 1722, Jan. 3-7, 2005 Baur, C. et.al., Journal of Solar Energy Engineering, 129, 258-265, Aug. 2007 King, R.R. et. al., Applied Physics Letters, 90, 183516, 2007.

新能源作业

新能源作业

家庭式新能源发电系统以自己家庭为例,分析典型家庭用电情况。

我们家一年平均月用电量为269.8度,平均日耗电量为9度,用电量高峰集中在6-8月份,因为家里需要使用空调降温,使用热水器的频率也增大了,所以耗电多。

冬季较春夏用电量略多,应该是因为室内活动时间增多且夜长昼短,照明、电视、厨房用电都相对增多。

1.四川省新能源资源情况分析1)太阳能全省年太阳能理论蕴藏量约为2133.2 J,折合成标准煤相当于10466kg/2m,太阳能资源相当丰富。

目前大型地面太阳能发电主要考虑年太阳总辐射不低于5500MJ/ 2m,日照时数超过2000h,场址为荒地、沙地等闲置性土地的地区。

经初步统计,全省满足上述条件,可用于太阳能发电的土地面积约1430 2kW计,全省太阳能发电实际可开发量约为km,装机规模以3万2/km4290万kW。

四川省太阳能分布很不平衡,大致以龙门山脉,邛崃山脉和大凉山为界,东部较差,西部较好。

全省太阳能资源最丰富地区年总辐射量达6000MJ/2m以上,年日照时数为2400-2600h,主要地区包括石渠、德洛、甘孜、理塘、稻城、攀枝花、阿坝州等。

2)风能根据四川省风能资源概况,风功率密度等级达到2级以上的范围约占全省总面积的2%。

按照四川省山地风电场特点,估算全省风能资源理论开发量约为5840万KW。

在当前风力发电技术条件下,根据全省风能资源、工程地质、接入系统、交通运输等建设条件,按照当前技术经济水平、上网电价及收益率要求等,初步估算全省风能实际可开发量约为1360万KW(随风电技术、资源观测开发条件等外部环境变化,理论量和实际开发量会发生一定变化)。

四川省风能资源主要分布在西北部高原、西南部山区、盆地北部山区等海拔高度1000-4000m,具体行政区包括凉山、攀枝花、广元、甘孜、阿坝、达州、雅安等。

从季节分布上来看,风能资源主要集中在冬春季节,基本是河流枯水期,恰能弥补四川省枯水期水电出力不足的缺陷。

毕业设计(论文)文献综述讲解

毕业设计(论文)文献综述讲解

重庆理工大学文献综述二级学院光电信息学院班级112160101学生姓名陈珊珊学号11216010101太阳能电池表面减反膜的研究陈珊珊摘要在太阳能电池表面形成一层减反射薄膜是提高太阳能电池的光电转换效率比较可行且降低成本的方法。

减反膜能减少太阳电池表面反射,提高电池效率,因此近年来得到了极大的关注。

本文结合国内外对太阳能减反膜的研究现状,概括了减反膜的基本原理,叙述了几种目前常用的减反膜的制备方法及其工艺特点,针对目前的研究状况展望太阳能电池减反膜的发展前景。

关键词:减反膜原理制备方法及工艺发展前景1.引言随着世界传统能源供应短缺的危机日益严重,太阳能作为“取之不尽、用之不竭”的清洁、可再生能源愈发得到重视,太阳能的开发与利用具有巨大的发展空间和潜力。

太阳能电池就是利用太阳能的光电转化效应将太阳能转化为电能,影响电池效率的一个重要因素是电池对入射光的利用率。

根据菲涅尔反射原理,在电池表面制备减反射膜,可以减小入射光反射,增加光子有效吸收[1]。

如果能够提高太阳能电池及其组件的光利用率,则可以提高太阳能电池组件的发电量,而太阳能电池减反膜能有效地减少光的反射,对提高太阳能电池光电转换效率具有重要意义[2]。

减反射膜必须具备较强的耐磨性,才能在长期使用过程中,保持较高的光透过率,获得理想的光电转换效果。

目前的研究和应用主要集中在太阳能电池硅表面制备减反膜,降低对光的反射,以及在太阳能电池组件的超白玻璃上镀减反膜,增加太阳光的透过率,从而提高转化效率。

2.太阳电池减反膜的原理及设计策略减反膜设计的理论基础就是薄膜的干涉[3,4]。

如图1a所示,对于理想均匀单层减反膜的n1必须满足以下两条件: (1)n1=(n0n s)1/2,n0和n s分别是空气和基底的折射率。

(2)n1d =λ/4,d是薄膜厚度,λ是入射光波长。

对于多层薄膜,它的数学模型有很大差异,如图1b所示。

对于玻璃基底(n s= 1.5) ,减反膜材料的n1理论值等于1.22。

8英寸半导体级硅单晶抛光片

8英寸半导体级硅单晶抛光片

8英寸半导体级硅单晶抛光片介绍在半导体制造业中,硅单晶抛光片是非常重要的材料之一。

其中,8英寸半导体级硅单晶抛光片是一种常见的规格。

本文将对8英寸半导体级硅单晶抛光片进行全面、详细、完整且深入地探讨和介绍。

什么是8英寸半导体级硅单晶抛光片?8英寸半导体级硅单晶抛光片指的是直径为8英寸(约203.2毫米)的硅单晶片,在抛光过程中,经过一系列的物理和化学处理,使其表面变得光滑和平整。

这种硅单晶片具有高纯度、低杂质含量以及均匀的结晶结构,非常适用于半导体器件的制造。

制备过程8英寸半导体级硅单晶抛光片的制备过程一般包括以下几个步骤:1. 去除不纯物质首先,将原始硅单晶片进行预处理,去除表面和内部的不纯物质。

这通常包括酸洗、溶剂清洗和高温热处理等步骤。

2. 物理抛光接下来,对硅单晶片进行物理抛光。

这一步骤使用机械手段,将硅单晶片放置在旋转的抛光盘上,并利用研磨液和研磨颗粒进行抛光。

通过控制抛光时间、抛光液的成分和研磨颗粒的大小,可以控制硅单晶片的表面光洁度和平整度。

3. 化学机械抛光在物理抛光之后,会进行化学机械抛光。

这一步骤结合了化学物质和物理力学,通过在硅单晶片表面生成一层化学反应产物,并用研磨颗粒进行机械抛光,以进一步提高表面的光洁度和平整度。

4. 清洗和检验最后,在抛光完成后,将硅单晶片进行清洗,去除抛光液和杂质等残留物。

然后,对抛光片进行严格的检验,包括检查表面光洁度、平整度、厚度等指标,以确保其质量符合要求。

应用领域8英寸半导体级硅单晶抛光片在半导体制造业中广泛应用。

其作为半导体器件的基底材料,能够提供良好的机械强度和热传导性能。

主要应用领域包括:1. 集成电路制造8英寸半导体级硅单晶抛光片是集成电路制造中不可或缺的材料之一。

通过在硅单晶片上制造各种器件结构,如晶体管和电容器等,从而实现电路功能。

2. 光电子学由于8英寸半导体级硅单晶抛光片能够提供优异的光学特性,因此在光电子学领域也有广泛的应用。

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VmpImp FF = VocIsc
(3-5)
• FF物理意义:衡量P-N结质量及串联电阻的参数, 填充因子越接近1,太阳能电池的质量就越好, 在理想情况下,它仅仅是开路电压的函数。 • 填充因子的经验公式(Green,1982):
voc − ln(voc + 0.72) FF 0 = voc + 1
• 寄生电阻对最大输出功率的影响(续)
• 太阳能电池的量子效率(QE,EQE)
– QE:假设照射到太阳电池上的光子流为nph,这 些光子在电池内部产生电子空穴对(ne=IL/q), 最终这些载流子对太阳能电池输出电流产生贡献 的概率。一般都指外部量子效率,即EQE. – EQE: EQE= IL/(qnph) = Isc/(qnph) = ne/ nph (3-9a) EQE可以实验测得。 ne、nph分别为单位时间内通过外电路的电子流量 和波长为λ的入射光子流量。
第三章 太阳能电池的特性
内容
3.1 3.2 3.3 3.4 光照的影响 光谱响应 温度的影响 寄生电阻的影响
3.1 光照的影响 • 光照射到电池上的情形:见图3-1.
3、5是希望得 到的,也是设 计目标。
• 载流子的流动与复合:见图3-2、3-3.
在P-N结电场E的作用下,电子受力向N型一侧移动,空穴向P型一侧移动。图 3-2为理想载流子收集情况(短路条件下);图3-3为收集与复合共存的情形。
• 光照下I-V曲线及图(图3-4)
IL为光生电流,其方向同饱和暗电流I0。式3-1同二极管公式2-2.
光照使得电池的I-V曲线向下平行移至第四象限,于是二极管的电能可以被 获取。
• 输出功率:I-V曲线的内接长方形的面积。 • 曲线变换:将I-V曲线上下翻转,见图3-5, 此时公式3-1变为式3-2.
• a)无光照时热平衡态,NP 型半导体有统一的费米 能级,势垒高度为qUD=EFN-EFP。 • b)稳定光照下P-N 结外电路开路,由于光生载流 子积累而出现光生电压Uoc 不再有统一费米能级, 势垒高度为q(UD-Uoc)。 • c)稳定光照下P-N 结外电路短路,P-N 结两端无 光生电压,势垒高度为qUD,光生电子空穴对被 内建电场分离后流入外电路形成短路电流。 • d)有光照有负载,一部分光电流在负载上建立起 电压Uf,另一部分光电流被P-N 结因正向偏压引 起的正向电流抵消,势垒高度为q(UD- Uf)。
(3-2)
• 用以衡量在一定照射强度、工作温度以及面积下, 用以衡量在一定照射强度、工作温度以及面积下, 太阳电池电力输出的两个主要制约参数: 太阳电池电力输出的两个主要制约参数: – 短路电流(Isc):当电压为0时(外电路短路), 电池对外输出的最大电流。在理想情况下,如 果V=0,则由式(3-2)得Isc= IL,亦即Isc与所 接收的光照强度成正比。 – 开路电压Voc:当电流为0(I=0)时,电池输出 的最大电压。 Voc的值随辐射强度的增加呈对 数方式增长,但最大值不超过接触电势差VD 。 但最大值不超过接触电势差V 但最大值不超过接触电势差 这个特性特别适合太阳能电池为蓄电池充电。
• 光谱响应度:每瓦特功率入射光所产生的 电流强度。
– 短波辐射情况下,电池无法利用光子全部能量。 – 长波辐射,电池对光线的吸收作用很弱,大部 分光子在远离P-N结的区域被吸收,也没有响 应。或者说,半导体材料的有限扩散长度限制 了电池对光的响应。 – 光谱响应度与波长的关系: 见图3-8.
• 光谱响应度计算式
P-N 结光电效应
• 当P-N 结受光照时,样品对光子的本征吸收和非本征吸收 都将产生光生载流子。但能引起光伏效应的只能是本征吸 本征吸 收所激发的少数载流子。因P 区产生的光生空穴,N 区产 收所激发的少数载流子 生的光生电子属多子,都被势垒阻挡 势垒阻挡而不能过结。只有P 势垒阻挡 区的光生电子和N 区的光生空穴和结区的电子空穴对(少 子)扩散到结电场附近时能在内建电场作用下漂移过结。 光生电子被拉向N 区,光生空穴被拉向P 区,即电子空穴 电子空穴 对被内建电场分离。 对被内建电场分离。 • 这导致在N 区边界附近有光生电子积累,在P 区边界附近 有光生空穴积累。它们产生一个与热平衡P-N结的内建电 场方向相反的光生电场 其方向由 区指向 区。此电场 光生电场,其方向由 光生电场 其方向由P 区指向N 使势垒降低,其减小量即光生电势差 光生电势差,P 端正,N 端负。 光生电势差 于是有结电流由P 区流向N 区,其方向与光电流相反。
Pin是入射光的功率,IQE是内部量子效率(Internal Quantum Efficiency), 是入射光的功率, 是内部量子效率( 是内部量子效率 ), R是反射率。EQE=(1-R)×IQE。当入射光波长趋于零时,因为每瓦特入射光 是反射率。 是反射率 × 。当入射光波长趋于零时, 中所包含的光子数目随波长减小而减少,所以SR趋于零 趋于零。 中所包含的光子数目随波长减小而减少,所以 趋于零。 电池光谱响应度对入射光波长的强烈依赖关系决定了太阳能电池性能 与太阳光的光谱成分密切相关。 此外,光学损失和载流子复合损失等其他因素,预示了实际太阳能电 池性能与计算中的理想值存在差距。
• 最大功率点Pmp与相应电流Imp电压Vmp
• 由图3-5及d(IV)/dV=0得: nkT Vmp Vmp = Voc − ln( + 1) q nkT / q
(3-4)
例如,n=1.3,Voc=600mV,对于典型硅太阳电池,Vmp大约比 Voc小93mV。
• 峰值功率或峰值瓦数Wp : 在强烈日光照射下(1kW/m2),最大功率点的输 出功率。 • 填充因子(FF,FIl Factor):
• 实际上,并非所产生的全部光生载流子都 对光生电流有贡献。 • 设N 区中空穴在寿命τp 的时间内扩散距离 为Lp,P 区中电子在寿命τn 的时间内扩散 距离为Ln。Ln+Lp=L 远大于P-N 结本身的 宽度。故可以认为在结附近平均扩散距离L 内所产生的光生载流子都对光电流有贡献。 而产生的位置距离结区超过L 的电子空穴对, 在扩散过程中将全部复合掉,对P-N 结光 电效应无贡献。
3.3 温度的影响
• 暗饱和电流:温度升高,饱和电流增大。
• 短路电流:温度升高,短路电流增大。
• 开路电压:温度升高,开路电压增大。
开路电压越大,受温 度影响越小。
• 填充因子FF
• 最大输出功率
3.4 寄生电阻的影响 • 太阳能电池常包含寄生串联电阻和分流电 阻,两种寄生电阻都会降低FF。见图3-10.
(3-7) (3-8)
voc定义为“归一化的Voc”,即voc= Voc /(nkT/q)
以上表达式仅适用于计算理想情况下的填充因子FF0,即 忽略寄生电阻造成的损耗时的填充因子FF0 。
3.2 光谱响应 • 不同能量的光子产生电子空穴对的情形
Eph≥Eg时,太阳能电池对入射光产生响 应,超出部分能量以热量形式散失。
• 量子效率QE与入射光波长的关系
• 量子效率QE与入射光波长的关系(续)
– 当Eg宽度介于1.0-1.6eV时,入射阳光的能量才 有可能被最大限度地利用。 – 单独考虑这个因素(Eg宽度介于1.0-1.6eV),太 阳能电池最大可能EQ限制在44%以下。 – 硅的Eg宽度1.1eV,砷化镓的Eg宽度1.4eV,后 E 1.1eV E 1.4eV 者更适合光伏应用。
• 两种寄生电阻
– 串联电阻Rs:源于半导体材料的体电阻、金属 接触与互联、载流子在顶部扩散层的运输,以 及金属和半导体材料之间的接触电阻。见图311. – 分流电阻Rsh:由于P-N结的非理想和结附近的 杂质造成,它引起结的局部短路,尤其是发生 在电池边缘。见图3-12.∆I=V
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