High-Efficiency Solar Coatings
简述压延法生产光伏玻璃的流程
简述压延法生产光伏玻璃的流程Rolling method is a common technique used in the production of solar glass. 压延法是生产光伏玻璃常用的一种技术。
It involves passing a hot glass ribbon between two rollers to achieve the desired thickness and surface finish. 这种方法涉及将热玻璃带在两个滚轮之间，以达到所需的厚度和表面光洁度。
The process begins with the melting of raw materials like silica sand, soda ash, and limestone in a furnace. 这个过程从在炉子中熔化原材料如硅砂、苏打灰和石灰石开始。
Once the molten glass is formed, it is poured onto a metal table and rolled out using a series of rollers. 一旦熔融玻璃形成，它被倒在一个金属桌上，然后通过一系列滚轮进行压延。
The glass is then annealed to relieve any internal stresses and improve its structural integrity. 玻璃随后会进行退火，以消除任何内部应力并提高其结构完整性。
This process ensures the glass is strong and durable enough to withstand the rigors of solar panel installation and long-term exposure to the elements. 这个过程确保玻璃足够坚固耐用，能够承受太阳能电池板安装的严苛条件及长期暴露于外部环境。
High absorptivity solar absorbing coatings
High absorptivity solar absorbing coatings*D. M. Mattox and R. R. SowellSandia Laboratories, Albuquerque, New Mexico 87115(Received 20 December 1973)A high absorptivity is essential in the efficient use of a solar collector. In this paper we review some of the fundamental considerations in solar absorbingcoatings and present reflectance data on several chemically treated surfaces which appear to be black in the solar spectrum. Reflectivity data are also presented for a lead sulfide “selective paint” which uses a silicone binder.INTRODUCTIONSolar energy is an extensive low-intensity energy source whose economic feasibility relies on efficient collection,retention, and utilization. Figure 1 shows the energy in the solar spectrum external to the earth’s atmo-sphere (m = 0) and after passing through two optical air masses (m=2).1 Note that >95% of the solar energy is confined to the region 0.3-2.0 µ. Figure 1also shows the radiant energy from blackbodies at various temperatures.2 Note that for low temperatures ( <300°C) most of the radiant energy is above 2 µ.This means that for effective collection and retention a solar collector should absorb strongly at wavelengths below 2 µ and not radiate (i.e., not absorb by Kirchoff’s law) at wavelengths >2 µ. The importance of this is shown in Fig. 2, where the amount of useful energy (collector efficiency) is plotted for a flat plate normal to the sun in space as a function of absorptance andtotal hemispherical emittance a = 1(i.e., a perfect blackbody at all wavelengths) the maxi-mum temperature that the plate can attain is 395 K),where the radiant energy is equal to the absorbed energy. For lower temperatures, heat may be extractedfrom the collector plate either as useful energy or as losses other than radiation. For a “selective absorber”where= 0.8 and> l]]is desirable, but it is essentialthatbe small for the operating temperature.Selective absorption can be accomplished by several techniques.4 Multilayer films can be designed to give selective absorption by interference effects,5 but this type of absorber is usually expensive and can suffer stability problems at high temperatures owing to in-terdiffusion of the layers. A second approach is to form a surface layer by coating or chemical reaction which will absorb the solar spectrum but be trans-mitting in the infrared. By forming this layer on a surface with low infrared emittance, such as a polished metal, a selective absorber can be obtained. Tabor and others have presented several such absorber sys-tems formed by chemical treatments.6-10F IG . 1. Solar spectrum external to the atmo-sphere (m=O) and after penetrating two stan-dard atmospheres (m = 2). Blackbody radiation curves for 300, 550, and 1000 K. Table of total radiant energy for solar and various black-iPERCENT OF EMITTED RADIATION BELOWRADIANT ENERGY 1.0793 J.Vac.Sci.Technol.,Vol.11,No.4,July/Aug..1974 CopyrightE0, from 0.5eV (2.5 µ) to 1.24 eV (1µ )n, which give high reflectivities at the air (vacuum)/semiconductor interface. For in-stance, polished PbS(n=4.1) in vacuum would have a normal reflectance of about 40%, [reflection coeffi-cient = (n- 1)2/(n+1)2]. This can be lowered by proper thickness control to get destructive interference at the wavelength of the solar maximum.12 The reflectance can be further decreased by the application of anti-reflection coatings13 or by making the coating porous.14 In the case of porous PbS the effective index of re-F IG. 3. Surface mor-phology of Ebanol Ctreated copper. A_as-treated ; B-after bur-nishing.I0.40.5 1.0 15 2.0 2.5VISIBLE 4-i SOLARµ).12 Where there is extensive porosity in the coating the collector efficiency may be affected by poor thermal conductivity.In addition to collector efficiency, cost and stability are prime considerations in solar collector fabrication. There are two general designs for solar collectors: flatplate and focused. The$2-$8/ft2 for a flat-plate collector and somewhat higher for a simple tracking focused collector. This leaves little money for collector coatings. Coating stability depends on the operating time, temperature, and at-mosphere. In this study, we have investigated the optical properties, thermal and photochemical stability of several surface treatments, and coatings for use in a relatively low-temperature (230°C) collector with a controlled atmosphere or vacuum protected by a glass cover which is transparent in the region indicated in Fig. 1.EXPERIMENTALCopper which has been chemically blackened using Ebanol C (trade name, Ethone, Inc., P.O. Box 1900, New Haven, Conn.06508, refer to Ethone data sheets for applications) or a NaOH/NaClO2mixture has been shown to exhibit desirable selective absorber properties.15 The as-treated surface has a velvet ap-pearance owing to a dendritic structure (Fig. 3) and is normally burnished after treatment. X-ray diffrac-tion shows that the surface is composed mostly of CuO with some Cu2O. Figure 4 shows the reflectivity of theJ. Vac. Sci. Technol., Vol. 11, No. 4, July/Aug. 1974795 D. M. Mattox and R. Ft. Sowell: High absorptivity solar absorbing coatingsEbanol C-treated surfaces after burnishing, as de-termined with a Beckman DK-2 spectroreflectometer.Burnishing of the surface increased the reflectivity several percent over the as-treated surfaces, whose reflectivity is near zero in the visible. Aging of the coatings by heating in air to 245°C for 244 h causes an increase of ~3% in the reflectivity, though there was no detectable change in chemical composition.Heating in air also caused oxidation to proceed at the interface, causing loss of adhesion. Aging under uv radiation (mercury vapor lamp, ~2 mW/cm 2 for 196 h)caused no changes in reflectivity nor did heating in vacuum. Chemically blackened electrodeposited copper films on steel were found to behave in a similar manner.Figure 5 shows the infrared transmission properties of copper films blackened using Ebanol C as determined using a Perkin-Elmer model 21C double-beam infrared spectrophotometer. The sample was in the form of a completely oxidized copper film ground and pressed in a KBr pellet.Carbon steel can also chemically blackened using Ebanol S. This treatment forms Fe 3O 4 on the surface,with no noticeable change in surface morphology, and has good selective absorption properties.15 Figure 4shows the spectral reflectivity properties of a 1018steel surface treated with Ebanol S. No change in reflectivity or surface composition was found on heating (230°C) or uv treatment in air.Stainless steel (304) was chemically blackened using Ebanol SS. The reflectivity of these surfaces is shown in Fig. 4 also. This surface is primarily F e 3O 4, and the reflectivity is stable on heating and uv treatment in air.Copper surfaces can be sulfided to form Cu 2S = 1.8 eV) coatings by treating in ammonium sulfide solutions. Figure 5 shows the reflectance of such a surface. Although the surface appears very black in the visible, it becomes transmitting in the near in-frared and the underlying copper surface reflects the infrared portion of the solar spectrum. Figure 5 also shows the infrared transmittance of Cu 2S formed by completely sulfiding a thin (~ 10 000 Å) copper film then grinding the film to a powder and pressing in a KBr pellet. This method of measurement was neces-sary since the film crumbled on sulfiding.F IG . 5. Reflectivity of Cu 2S surface and the transmittance of Cu 2S and coating formed by Ebanol C on copper. Transmission samples prepared by pressing coating powder in KBr pellet.PbS THIN FILM ( ~ 1500Å)10 11 12 13 14 15SOLAR 4WAVELENGTH (µm)F IG . 6. Transmission of PbS thin film as-deposited and aftervarious treatments. u v irradiation completely converted film to PbSO 4.Difficulties were encountered in chemically sulfiding lead surfaces, so lead sulfide films were formed by vacuum evaporation. Figure 6 shows the transmittance of PbS films as deposited on a KRS-5 substrate and after heating in air (230°C for 72 h) and after uv ir-radiation (2 mW/cm 2 for 72 h). The uv irradiation in air caused complete photooxidation of the sulfide to lead sulfate (PbSO 4). No such effect was seen on uv treatment in vacuum (187 h), showing that the PbS is stable in a vacuum environment.The use of “selective paints” has been proposed.”Finely divided PbS (-0.1-y particles) was formed by precipitation from lead acetate solution by bubbling H 2S , washing the precipitate, and then freeze drying.The precipitate was mixed with an activated silicone resin (Dow Corning 805,l655 w t.% PbS) and cured for 16 h at 200°C. Figure 7 shows the reflectivity ofthe paint thus formed. The silicone resin used has aC-SiC-HMe3 4 5 6 7 8 9Vac. Sci. Technol., Vol. 11, No. 4,July/Aug. 1974SUMMARYThe Ebanol chemical oxidizing treatments do formsolar black coatings with a relatively low reflectivity (5-l0%). Since these metal oxides are not transparent in the near infrared, they are not expected to be selective absorbers to any great degree. Copper sulfidecoatings are black in the visible but allow reflection of a large amount of the solar infrared (~15% of total).They should have low infrared emittance. Lead sulfide selective paint is very black in the solar (<5% re-flectivity), but the emissivity in the infrared probably depends on the amount of binder in the paint.ACKNOWLEDGMENTSThe authors would like to thank T. M. Myers forsome of the optical measurements and G. J. Kominiak for film preparation and some optical measurements.Note added in proof. Solar absorptance values (a,)for m = 2 are : Ebanol ss on 340 ss = 0.91; Ebanol s on 1018 steel =0.88; Ebanol c on copper (burnished)=0.91; Cu 2S=O.79 and PbS paint=0.94.rted bv the US Atomic Energv Commission.J. G. Robertson, Sol. (1973).*suppo 1R. K. Swartman, C. Swaminathan, and Energy 14, 1972Thermal Touloukian,1972) Vo 3R.M. VanRadioactive Properties (Coatings), edited by Y. S.D. P. Dewitt, and R. S. Herniz (Plenum, N.Y. 6H. Z . Tabor Transactions of the Conference on the Use of SolarEnergy (University of Arizona Press, Arizona. 1958). Vol. II.Pt. I, Sec. A.7J. T. Gier and R. V. Dunkle, Transactions of the Conference on the Use of Solar Energy (University of Arizona Press, Arizona,1958), Vol. II, Pt. I, Sec. A, p. 41.8H. Z. Tabor, Bull. Res. Counc. Isr. 5A . 256 (19.56).9H . Z . Tabor, US Patent 2 917, 195910H. C. Hottel and T. A. Unger, Publication No. 71 of the MIT Solar Energy Conversion Project, 1958.11J. G. N. Braithwaite. I. Sci. Instrum. 32. 10 (1955).12D. A. Williams, T. A. Lappin, and J. A. Duffie, J. Eng. Power,47, 123 (1963).l3H. V. N.Yadava, S. K. Sharma, and K. L. Chopra, Thin Solid Films 17, 243 (1973).14M. Garnett, Philos. Trans. R. Soc. Lond. 203, 385 (1904) ;Philos. Trans. R. Soc. Lond. 205, 237 (1906).15E. A. Christie, “Spectrally Selective Blacks for Solar Energy Collection,”presented at the International Solar Energy Society Conference, 1970, Melbourne, Australia, paper 7/81.16"Silicone Protective Coating Resins,” Dow Corning Bulletin 07-349, 1970.17W. R. Wade and W. S. Slemp, “Measurement of Total Emeittance of Several Refractory Oxides, Cermets, andCramics for Temperatures from 600°F to 2,000°F ," NASA Technical Note D-998.J. Vac. Sci. Technol., Vol. 11, No. 4, July/Aug. 1974。
High-Efficiency HIT Solar Cells for Excellent Power Generating Properties
Mater. Res. Soc. Symp. Proc. Vol. 1123 © 2009 Materials Research Society1123-P03-01High-Efficiency HIT Solar Cells for Excellent Power Generating Properties Toshihiro Kinoshita, Daisuke Ide, Yasufumi Tsunomura, Shigeharu Taira, Toshiaki Baba, Yukihiro Yoshimine, Mikio Taguchi, Hiroshi Kanno, Hitoshi Sakata and Eiji Maruyama Advanced Energy Research Center, Sanyo Electric Co., Ltd, Kobe 651-2242, JapanABSTRACT In order to achieve the widespread use of HIT (Hetero-junction with Intrinsic Thin-layer) solar cells, it is important to reduce the power generating cost. There are three main approaches for reducing this cost: raising the conversion efficiency of the HIT cell, using a thinner wafer to reduce the wafer cost, and raising the open circuit voltage to obtain a better temperature coefficient. With the first approach, we have achieved the highest conversion efficiency values of 22.3%, confirmed by AIST, in a HIT solar cell. This cell has an open circuit voltage of 0.725 V, a short circuit current density of 38.9 mA/cm2 and a fill factor of 0.791, with a cell size of 100.5 cm2. The second approach is to use thinner Si wafers. The shortage of Si feedstock and the strong requirement of a lower sales price make it necessary for solar cell manufacturers to reduce their production cost. The wafer cost is an especially dominant factor in the production cost. In order to provide low-priced, high-quality solar cells, we are trying to use thinner wafers. We obtained a conversion efficiency of 21.4% (measured by Sanyo) for a HIT solar cell with a thickness of 85µm. Even better, there was absolutely no sagging in our HIT solar cell because of its symmetrical structure. The third approach is to raise the open circuit voltage. We obtained a remarkably higher Voc of 0.739 V with the thinner cell mentioned above because of its low surface recombination velocity. The high Voc results in good temperature properties, which allow it to generate a large amount of electricity at high temperatures. INTRODUCTION To cope with increasing demands for high-quality solar cells from all over the world, we plan to expand the annual production of HIT solar cells from 340 MW in FY 2008 to more than 600 MW in FY 2010. At the same time, we will increase the pace of development to offer technical advantages into our future products. We plan to raise cell conversion efficiency to 23.5% in the laboratory by 2010. We developed a high-efficiency solar cell structure known as the HIT structure, and have been raising its quality. We recently updated the world’s highest conversion efficiency of 22.3 % with a practical-sized solar cell in June 2007 [1]. Also, using high-efficiency HIT cells, we have achieved a record conversion efficiency of 20.6% for an R&D prototype module, which was certified by Advanced Industrial Science and Technology (AIST) [2]. These technologies are being steadily transferred to production. This paper describes the high-efficiency technologies and characteristics of HIT solar cells. HIT SOLAR CELL STRUCTURE The HIT solar cell is primarily characterized by its high conversion efficiency. It is also appreciated for its excellent temperature coefficient, the potential that it offers for using a verythin Si wafer, and the possibility for its application to bifacial solar modules. As shown in figure 1, an intrinsic (i-type) amorphous silicon (a-Si) layer followed by a p-type a-Si layer are deposited on a randomly textured n-type CZ crystalline silicon (c-Si) wafer to form a p/n heterojunction. On the opposite side of the c-Si wafer, i-type and n-type a-Si layers are deposited to obtain a Back Surface Field (BSF) structure. On both sides of the doped a-Si layers, Transparent Conducting Oxide (TCO) layers as an antireflective coating consisting and metal grid electrodes are formed. The symmetrical structure of the HIT cell is suitable for a bifacial module. All processes are conducted in temperature below 200 ºC.Grid electrode p-type a-Si: ~ 0.01 m i-type a-Si~ 0.01 mc-Si (CZ, n-type)n-type a-Si: ~ 0.01 mTCO(Transparent Conductive Oxide)Figure 1. The structure of a HIT solar cell. By developing a high-quality i-type a-Si layer, the defect level on the c-Si surface can be considerably reduced, and a high Voc can be obtained [3]. The excellent c-Si/a-Si hetero interface of the HIT structure leads to a outstandingly high Voc of more than 0.72 V. A higher Voc allows for not only a high conversion efficiency but also en excellent temperature coefficient, that excels the temperature coefficient of a diffused c-Si solar cell and is almost comparable to that of an amorphous Si solar cell. This feature results in higher output power even at higher temperatures. CONVERSION EFFICIENCY TREND Figure 2 shows the trend in the conversion efficiency of HIT solar cells. We are aiming for a high conversion efficiency of over 23.5% in our R&D by the end of 2010. As a result of our aggressive studies, we achieved a record high conversion efficiency of 22.3% (Voc: 0.725 V, Isc: 38.9 mA/cm2, FF: 0.791, total area: 100.5 cm2, certified by AIST) in July 2007, as shown in figure 3.24.0 Conversion efficiency (%)22.3%22.0 20.0 18.0 16.0 14.0(Jul. 2007)22.0%(Apr. 2007)R&D prototype ( ~ 100 cm2 )96 98 00 02 04 06 08 10 YearFigure 2. Trend in the conversion efficiency of HIT cells.Figure 3. I-V characteristics of the HIT solar cell certified by AIST, which shows the world’s highest conversion efficiency of 22.3% for a practical size cell (> 100 cm2). As an approach for a product with even higher quality, we have been developing module technologies for maximizing long-term stability and module efficiency by taking advantage of the HIT cell’s excellent features. As a result, we have demonstrated very high conversion efficiency with an R&D prototype module. The module efficiency has reached 20.6 %, which was certified by AIST in December 2007. This achievement also indicates the future superiority of HIT modules. APPROACHES FOR HIGHER CONVERSION EFFICIENCY We have been focusing on the following techniques for obtaining a high conversion efficiency with the HIT structure: (a) Improving the HIT structure by enhancing the a-Si/c-Si heterojunction properties for a higher Voc, (b) Improving the grid electrode for a higher Isc and FF, and (c) Reducing the absorption loss of the TCO layer for a higher Isc. (a) Improving the HIT structure The high Voc of the HIT solar cell is achieved by the effective passivation of c-Si surface defects with a high-quality intrinsic a-Si layer. The following fabrication processes are being used in the development of these solar cells: Cleaning the c-Si surface with low-cost wet cleaning processes before a-Si deposition Depositing a high-quality intrinsic a-Si layer by chemical vapor deposition Maintaining low plasma and thermal damage to the c-Si surface and heterojunction while fabricating the a-Si, TCO layers and grid electrode. By using these processes, the carrier recombination is decreased, resulting in fewer localized states in the intrinsic layer and interface of the heterojunction [4]. We have decided to target a Voc value of more than 0.74 V by unifying these techniques to achieve our conversion efficiency goal. (b) Optimizing the grid electrode For a higher Isc and FF, the grid electrode requires lower resistance and finer lines for a larger aperture, simultaneously. Since the grid electrode of HIT solar cells is made of silver (Ag)paste, which has high resistivity in itself, the aspect ratio must be as high as possible. Figure 4(a) shows a conventional grid electrode fabricated by the screen-printing method. The conventional grid electrode has a spreading area that causes optical loss. In order to lower the optical loss and the resistance loss, it is necessary to eliminate this spreading area and raise the height, as shown in figure 4(b).(a) Conventional grid electrode (Low aspect ratio) S w (b) Ideal grid electrode (High aspect ratio) S w Finer Higher Spreading areaFigure 4. Schematic diagrams of (a) a conventional grid electrode with a spreading area and low aspect ratio, and (b) an ideal grid electrode with no spreading area and high aspect ratio. (c) Reducing the absorption loss There are optical losses in the short and long wavelength regions. The optical loss in the long wavelength region is mainly caused by the absorption of TCO. The HIT structure uses the TCO on the surface to collect the generating carriers. A lower level of optical absorption loss and a higher electrical conductivity for the TCO layer will lead to a higher Isc and FF. The optical absorption loss in the TCO is mainly caused by free carrier absorption. The deposition conditions of the TCO have been optimized to obtain a high-quality TCO layer with high carrier mobility. The new TCO shows better sensitivity in the long wavelength region (>1,000 nm) of the IQE spectra. Furthermore, the high FF value (0.791) in HIT solar cells using the new TCO suggests high conductivity for high carrier mobility [5]. UTILIZING A THIN WAFER FOR THE HIT CELL The wafer accounts for about half the cost of a solar module. We have been developing thinner HIT solar cells to reduce the power-generating cost. Here, we have evaluated the possibility of thinner HIT solar cells for the first time. Figure 5 shows a picture of a HIT solar cell with a c-Si wafer thickness of ~85µm.Figure 5. A HIT solar cell using an 85-µm-thick c-Si wafer. Note that no sagging is seen.The I-V curve of the HIT solar cell on an 85-µm- thick c-Si wafer is shown in figure 6. We obtained a high conversion efficiency of 21.4% with this HIT solar cell. The Voc is an extremely high value of 0.739 V, the Isc is 37.3 mA/cm2, and the FF is 77.6% [6]. These values were measured under standard conditions in-house. The Jsc value with the 85-µm-thick wafer decreased about 3% in comparison with that of a 165-µm-thick wafer. Those values corresponded approximately to the values calculated using SUNRAYS [7].40 35 30 25 20 15 10 5 0 0 Current density (mA/cm)2Eff.: 21.4% Voc: 0.739 V Jsc: 37.3 mA/cm2 FF: 0.7760.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Voltage (V)Figure 6. The I-V curve of a HIT solar cell with an 85-µm- thick c-Si wafer, which was measured at SANYO (measurement conditions: AM 1.5, 1 SUN, 25.0 ºC, cell size (aperture size): 103.3 cm2). Figure 7 shows the thickness dependence of I-V parameters normalized by those of a 165µm-thick HIT solar cell. As the thickness of the c-Si wafer decreases, the Isc decreases. This decrease in Isc is caused by insufficient light absorption and agrees well with the calculated result using SUNRAYS. On the other hand, the Voc shows no decrease because of the excellent HIT passivation effect on the c-Si surface. However, there seems to be a slight decrease in FF of about 0.5-1%. This result suggests that we still have room to improve the a-Si/c-Si heterojunction performance toward a thinner, next-generation c-Si wafer structure below 100µm.1.04 Isc Voc EffRelative value to 165-µ m-thick cell1.021.000.980.96 50 100 150 200 HIT cell ThicknessFigure 7. The Isc, Voc and conversion efficiency of HIT solar cells as functions of various HIT cell thicknesses. The values are normalized by that of a 165-µm-thick HIT cell.We are now focusing on developing optical confinement technologies to improve the Isc, and enhanced passivation technologies to improve the FF toward the next generation. These results suggest that the HIT structure is suitable for thinner Si wafers with high conversion efficiency. However, the light confinement design is a very important factor for further improving the Isc in a thin HIT cell structure. This will enable the HIT structure to reduce the wafer cost while maintaining high conversion efficiency. IMPROVING THE TEMPERATURE COEFFICIENT Generally, an excellent temperature coefficient for the conversion efficiency enables high performance in outdoor use, which leads to a number of user benefits. As shown in figure 8, the temperature coefficient mainly depends on the Voc of the solar cell. Therefore, the HIT solar cell with its high Voc exhibits an excellent temperature coefficient [8,9]. The temperature coefficient of the HIT solar cell with 0.736 V is -0.23 %/ºC. This is comparable to that of an a-Si solar cell, which is generally said to have an excellent temperature coefficient. Consequently, improving the temperature coefficient helps to reduce power-generating costs by further improving the Voc, such as by thinning wafers.Figure 8. Temperature coefficient of conversion efficiencies as a function of the Vocs of solar cells. APPLICATION TO A BIFACIAL SOLAR MODULE The front and back symmetrical structure of the HIT solar cell, as shown in figure 1, allows it to be applied to a bifacial solar module using a transparent back sheet such as glass. When we install this module, scattered light and light that is reflected from the ground are incident on the solar module from the backside. In our experiments, the output power of a bifacial solar module was higher by around 20% than that of a standard HIT solar module. That value depends on mounting conditions, such as the mounting angle, the ground reflectance, and the interval between modules. Vertical mounting allows us to apply it, for example, to a fence, a door, or a handrail. Horizontal mounting allows us to apply it, as shown in figure 9, to the roof of a bus stop.Figure 9. HIT Double used for the roof of a bus stop in Osaka, Japan. Figure 10 shows output power by dependence on the mounting tilt angle. The output power of the bifacial modules is higher than those of the standard module. We effectively increased the output power of the bifacial solar modules by increasing the tilt angle over that of standard modules. At a tilt angle of 60 degrees, the increase of output power relative to that of the standard module is 25%. Meanwhile, the relative increase is 17% at a tilt angle of 30 degrees. This allows the HIT Double to be used in a wide range of applications. It should, however, be noted that the amount of increase of output power with bifacial solar modules greatly depends on the installation environment.Average power generation (a.u.)Figure 10. A comparison of output power between standard and bifacial modules with various mounting tilt angles. Values are normalized at that of a HIT standard module with a tilt angle of 30 degrees. Ground reflectance: 0.4, Module height from the ground: 3.28 feet, Facing direction: south. Date: May 22 - June 21. SUMMARY We have described the excellent power generating properties of HIT cells.We have been focusing on the following techniques for obtaining high conversion efficiency with the HIT structure. We plan to raise the cell conversion efficiency to more than 23.5% in the laboratory by the end of 2010. To do this, we must simultaneously improve the HIT structure to increase the Voc, optimize the grid electrode and reduce the absorption loss to increase the Isc. In terms of utilizing thinner Si wafers, we have exhibited a high potential for use on thinner c-Si wafers. We obtained a high conversion efficiency of 21.4% and an extremely high Voc value of 0.739 V (AM 1.5, 1 SUN, 25ºC, cell thickness: 85 µm, cell size (AP): 103.3 cm2 measured in-house). The Voc increases as the thickness of the c-Si wafer decreases, due to the extremely low surface recombination velocity with excellent passivation on the c-Si surface. The excellent temperature coefficient results in generating more output power at high temperatures by further improving the Voc, such as by thinning the wafer and improving the HIT structure. The application of the HIT solar cell to a bifacial solar module has been commercialized as the "HIT Double," which is used for a wide range of practical applications for generating electricity. Consequently, the excellent power generating properties of HIT solar cells will make it possible to reduce the power generating cost. REFERENCES 1. S. Taira et al., “Our Approaches for Achieving HIT Solar Cells With More Than 23% Efficiency”, 22nd EU-PVSEC, pp. 932-935 (2007). 2. H. Kanno et al., “Over 22% Efficient HIT Solar Cell”, 23nd EU-PVSEC (2008)(in press). 3. M. Taguchi et al., “Improvement of the Conversion Efficiency of Polycrystalline Silicon Thin Film Solar Cell”, Fifth PVSEC, pp. 689-692 (1990). 4. M. Tanaka et al., “Development of New a-Si/c-Si Heterojunction Solar Cells: ACJ-HIT (Artificially Constructed Junction-Heterojunction with Intrinsic Thin-Layer)”, Jpn. J. Appl. Phys. 31, pp. 3518-3522 (1992). 5. Y. Tsunomura et al., “Twenty-two percent efficiency HIT solar cell”, Solar Energy Materials & Solar Cells (2008). 6. D. Ide, et al., "Excellent power-generating properties by using the HIT structure", 33rd IEEE PVSEC (2008). 7. R. Brendel, “SUNRAYS: A Versatile Solar Cell Ray Tracing Program for the Photovoltaic Community”, Twelfth EC Photovoltaic and Solar Energy Conf., p. 1339 (1994). 8. S. Taira et al., “Temperature Properties of High-Voc HIT Solar Cells”, Renewable energy, pp. 115-118 (2006). 9. A. Terakawa et al., “High Efficiency HIT Solar Cells and the Effects of Open Circuit Voltage on Temperature Coefficients”, Fifteenth PVSEC (2005).。
ALD原子层沉积技术的应用
硬盘
Smaller critical dimensions and more challenging topographies of magnetic recording heads have led to a need to replace conventional physical vapor deposition (PVD) coating technology with a more conformal coating method. ALD was selected as a new method to enable further scaling down. An additional benefit of ALD was the high quality of ultrathin insulating layers with low pinhole density. ALD AlOx has been used in read heads for several years, and ALD thin films and nanolaminates are being investigated for other applications in the read/write head process flow, such as trench filling, tunneling barriers, and encapsulation.
ALD is a powerful technology for this development work, as surface chemistry has an important role in the selection and optimization of materials, processes, and process conditions for electronic devices.
High-Efficiency Solar Cell-ppt
Best Research-Cell Efficiencies
36 32 28 Efficiency (%) 24 20 16 12
Masushita
Multijunction Concentrators Three-junction (2-terminal, monolithic) Two-junction (2-terminal, monolithic) Crystalline Si Cells Single crystal Multicrystalline Thin Film Technologies Cu(In,Ga)Se2 CdTe Amorphous Si:H (stabilized) Emerging PV Dye cells Westing- ARCO house Organic cells
36 32 28 Efficiency (%) 24 20 16 12 8 4 0 1975
RCA Spectrolab
Best measured cell efficiencies:
• 39% concentrator • 25% crystalline silicon • 19% thin films • 11% dye cells • 4.5% organic PV
UNSW
UNSW
UNSW NREL Cu(In,Ga)Se2 14x concentration UNSW NREL NREL NREL NREL NREL United Solar
Sharp
Georgia Tech
Varian
NREL Euro-CIS Boeing
Solarex
ARCO
High-efficiency silicon heterojunction solar cells
Plasma Processing Dr. Bartlomé/
Dr.Parascandolo
Flexible Si
Dr. Haug, Dr. T.Daudrix
Packaging
Dr. Theron Dr. Perret
a-Si/c-Si heterojunctions
Dr. De Wolf
Field-effect passivation
5
Open-circuit voltage: heterojunctions
Heterojunction solar cell
Chemical passivation
Hydrogenated a-Si provides excellent passivation of c-Si surface Charge can trickle through a-Si layers; recombination-active contacts are displaced from cSi surface
7
Open-circuit voltage: Pushing the limit
For 100-µm-thick c-Si wafer, theory predicts Voc, max = 769 mV Commercially available c-Si cells: Voc ≈ 650 mV Record-efficiency PERL c-Si cell: Voc = 706 mV Sanyo Si heterojunction cell: Voc = 745 mV!
100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 EQE and 1-reflection (%)
太阳能电池钙钛矿层
太阳能电池钙钛矿层英文回答：Solar cells made from perovskite materials have gained significant attention in recent years due to their high efficiency and low cost. Perovskite is a type of mineral that has a unique crystal structure, which allows it to absorb a wide range of light wavelengths. This property makes it an ideal material for solar cells, as it can efficiently convert sunlight into electricity.One of the main advantages of perovskite solar cells is their high power conversion efficiency. The efficiency of a solar cell refers to the percentage of sunlight that is converted into usable electricity. Perovskite solar cells have achieved impressive efficiencies of over 25%, which is comparable to traditional silicon solar cells. This high efficiency means that perovskite solar cells can generate a significant amount of electricity from a relatively small surface area.Another advantage of perovskite solar cells is their low manufacturing cost. The materials used to make perovskite solar cells are abundant and inexpensive, which makes them a cost-effective alternative to traditional solar cells. Additionally, perovskite solar cells can be fabricated using simple and scalable processes, such as solution-based methods. This further reduces the production cost and makes perovskite solar cells more accessible to a wider range of consumers.Despite these advantages, there are still some challenges that need to be overcome before perovskite solar cells can be widely adopted. One of the main challenges is their stability. Perovskite materials are sensitive to moisture and heat, which can degrade their performance over time. Researchers are actively working on developing strategies to improve the stability of perovskite solar cells, such as encapsulation techniques and the use of protective coatings.Another challenge is the scalability of perovskitesolar cell production. While the manufacturing processesfor perovskite solar cells are relatively simple, scaling up production to meet the demand for large-scale deployment is still a challenge. This is because the deposition of perovskite materials requires precise control over the fabrication conditions, which becomes more difficult as the size of the solar cells increases.In conclusion, perovskite solar cells offer a promising solution for renewable energy generation due to their high efficiency and low cost. However, further research and development are needed to improve their stability and scalability. With continued advancements in perovskitesolar cell technology, we can expect to see more widespread adoption of this renewable energy source in the future.中文回答：钙钛矿材料制成的太阳能电池近年来备受关注，因为它们具有高效率和低成本的特点。
太阳能光电、光热转换材料的研究现状与进展
第45卷第11期2017年11月硅酸盐学报Vol. 45，No. 11November，2017 JOURNAL OF THE CHINESE CERAMIC SOCIETY DOI：10.14062/j.issn.0454-5648.2017.11.03 太阳能光电、光热转换材料的研究现状与进展王聪，代蓓蓓，于佳玉，王蕾，孙莹(北京航空航天大学物理学院太阳能物理实验室，北京 100191)摘要：重点探讨了太阳能光电、光热转换技术领域的材料研究现状与发展，主要包括光伏电池半导体材料和太阳光谱选择性吸收涂层光学材料膜系。
太阳电池材料的关键问题还是成本与光电转换效率，钙钛矿太阳电池的研究成为光伏电池新的研究热点。
太阳光谱选择性吸收涂层是太阳能光热利用领域的核心材料技术之一。
近年来，太阳能的中高温热利用，尤其是聚焦热发电技术，作为与光伏发电平行的另一种主流太阳能发电方式，成为人们日益关注的焦点。
另外，还阐述了中高温太阳光谱选择性吸收涂层在国内外的研究成果和最新进展。
关键词：太阳能；光伏电池；太阳能聚焦热发电；太阳光谱选择性吸收涂层中图分类号：TK519 文献标志码：A 文章编号：0454–5648(2017)11–1555–14网络出版时间：2017–10–09 13:56:00 网络出版地址：/kcms/detail/11.2310.TQ.20171009.1356.014.html Recent Development and Advance of Solar Photovoltaic Materials and PhotothermalConversion MaterialsWANG Cong, DAI Beibei, YU Jiayu, WANG Lei, SUN Ying(Center for Condensed Matter and Material Physics, Beihang University, Beijing 100191, China)Abstract: The research status and advance of solar photovoltaic materials and photothermal conversion materials, which mean semiconductor solar cell materials and solar spectral selective absorbing coatings, were reviewed. The main problems of solar cell materials are cost and photoelectric conversion efficiency (PCE). The investigation of perovskite solar cell becomes a new research hotspot. On the other hand, solar selective absorbing coating is one of the key material technologies of solar thermal utilization. In recent years, medium-high temperature heat utilization of solar energy, especially the technology for concentrated solar power (CSP) as another mainstream of solar energy generation, is becoming a focusing in parallel with photovoltaic power generation. Thus this paper also talks about the research results and recent development of high temperature solar selective absorbing coatings as an important content.Keywords: solar energy; photovoltaic cell; concentrated solar power; solar selective absorbing coating太阳能作为一种取之不尽的清洁能源成为人类开发的重要绿色能源之一。
低吸收高发射热控涂层及填料发展展望
低吸收高发射热控涂层及填料发展展望张东，张有玮，张家强，张立功，崔庆新，白晶莹，孙浩然(北京卫星制造厂有限公司，北京100190)摘要：针对空间环境温差大、环境恶劣的问题，阐述了热控涂层在航天领域的重要性，以及未来航天器对热控涂层提出的高散热、轻量化、长寿命等新要求#结合常用涂层类型，重点介绍国内外低吸收高发射热控涂层的研制概况和现有喷涂型低吸收高发射热控涂层存在太阳光紫外波段光吸收过高、涂层性能退化快等问题。
阐明影响热控涂层热辐射性能的关键因素在于填料性能，然后对常用的热控填料进行总结，并对应用最广泛的氧化锌填料的改性方法和仍然存在的问题做出归纳，最后提出解决问题的方法是使用新型多孔材料介孔分子筛对氧化锌进行改性处理，并对改性方法进行调研#结果显示，此方法可以很好地解决现有涂层的问题并满足未来航天器对涂层的新要求#关键词：氧化锌；低吸收；高发射；热控涂层；热控填料；未来发展中图分类号:TG174.44文献标志码:ADevelopment Prospect of Low Absorption and High Emissivity Thermal Control Coatings and Pigments ZHANG Dong,ZHANG Youwei,ZHANG Jiaqiang,ZHANG Ligong,CUI Qingxin,BAI Jingying,SUN Haoran(Beijing Spacecraft Manufacturer Co.,Ltd.,Beijing100190,China)Abstract:In view of the problems of large temperature difference and harsh environment in the space environment,it was expounded that the importance of thermal control coatings in the aerospace field and the new requirements of high heat dissipation,lightweight and long-life for thermal control coatings put forward by spacecraft in the bined with the commonly used thermal control coating types,it was mainly introduced that the development of domestic and foreign low-absorption and high-emissivity thermal control coatings and the problems such as high absorption of solar ultraviolet band and rapid degradation of coatings performance of the existing spray-type low-absorption and high-emissivity thermal control coa t-ings.I t was clarified t h at t h e key fac t o r affec t i n g t h e t h ermal radiation performance of t h e t h ermal con t rol coating was t h e pigment s performance.Then t h e commonly used pigment s were summarized,and we concluded t h e mos t widely used zinc oxide pigment modification met h ods and t h e remaining problems.Finally,t h e proposed met h od to solve t h e problem was using a new porous ma t e rial mesoporous molecular sieve to modify zinc oxide,and t h e modification met h od was investiga t e d. Theresulsshowed ha hisme hodcouldsolve heexis ingcoaingproblemswelandmee henewrequiremen sof hefu-t u re spacecraft for t h e coa t i n g.Keywords：zinc oxide ,low absorption,high emissiv i t y,t h ermal con t r ol coatings,pigmen t ,fu t u re developmen t由于空间环境恶劣％&,温差达到上百摄氏度,而航天器内部的精密仪器无法抵抗如此巨大温差的高低温交变閃。
不同温度制备C3N4催化
/Langmuir©2009American Chemical SocietyPhotodegradation Performance of g-C3N4Fabricated by Directly HeatingMelamineS.C.Yan,†,§Z.S.Li,*,†,‡,§and Z.G.Zou†,‡,§†Eco-Materials and Renewable Energy Research Center(ERERC),Department of Physics and‡Department of Materials Science and Engineering and§National Laboratory of Solid State Microstructures,NanjingUniversity,Nanjing210093,P.R.ChinaReceived March17,2009.Revised Manuscript Received July3,2009The g-C3N4photocatalyst was synthesized by directly heating the low-cost melamine.The methyl orange dye(MO)was selected as a photodegrading goal to evaluate the photocatalytic activity of as-prepared g-C3N4.The comparison experiments indicate that the photocatalytic activity of g-C3N4can be largely improved by the Ag loading.The strong acid radical ion(SO42-or NO3-)can promote the degrading rate of MO for g-C3N4photocatalysis system.The MO degradation over the g-C3N4is mainly attributed to the photoreduction process induced by the photogenerated electrons. Our results clearly indicate that the metal-free g-C3N4has good performance in photodegradation of organic pollutant.IntroductionIn recent years,there has been increasing interest in the study of photocatalysis technology application in water/air purification,1 hydrogen production from splitting water,2self-cleaning coat-ings,3and high-efficiency solar cells.4This is related to serious environmental pollution and the global energy shortage.So far, various oxide,sulfide,and oxynitride semiconductor photocata-lysts have been developed to drive the photocatalytic reaction.5 However,one of the main goals in materials science fields is to find photocatalytic materials with high quantum efficiency.For water purification,an optical material is needed that has a band gap that absorbs visible light,strong oxidative ability,and high stability in a complex water solution system.Recently,Wang et al.6reported that a metal-free photocatalyst,graphite-like carbon nitride(g-C3N4),has the photocatalytic performance for hydro-gen or oxygen production from water splitting under visible light irradiation.Very recently,they developed the g-C3N4metal-including compounds to degrade organic dyes.7The functional organic-metal hybrid material exhibited modified electronic properties.However,the authors did not report the comparison results for degrading organic dyes over the bare and metal-ion-modified g-C3N4.The g-C3N4semiconductor is recognized to be the most stable allotrope at ambient conditions.Unlike the photocatalysts of sulfide and oxynitride semiconductor,the g-C3N4photocatalyst is stable under light irradiation in water solution as well as in acid(HCl,pH=0)or base(NaOH,pH=14) solutions due to the strong covalent bonds between carbon and nitride atoms.The high stability and moderate band gap imply that the metal-free g-C3N4has numerous potential applications in the photocatalysis fields.Several precursors,such as cyanamide,dicyandiamide,and melamine,have been used to obtain the g-C3N4solids.8The former two kinds of precursors are virulent and expensive in comparison to the latter one.So far,several research groups have reported that the g-C3N4can be fabricated by heat treatment of melamine in the low-vacuum system9,10or under high pressure.11 Depending on reaction conditions,g-C3N4with different degrees of condensation and properties was obtained.However,from an industrial applications viewpoint,the g-C3N4material obtained under ambient pressure was expected due to the low cost and facile operation.In the present paper,the g-C3N4photocatalyst powder was obtained by directly heating the melamine in a semiclosed system with two-step heat treatment.The melamine was first heated at500°C(heating rate:20°C/min)for2h,and the further deammonation treatment was set at520,550,and580°C for2h, respectively.For comparison,a reference sample was prepared by polymerization of cyanamide at550°C for4h.6The photode-gradation behavior of methyl orange(MO)over the as-prepared photocatalyst was studied.The sample of treated melamine at 520°C for2h exhibits high photodegradation activity.Our studies probably imply that the g-C3N4has the potential to treat industrial wastewater due to its good photodegradation perfor-mance and environmental adaptability.On the basis of our comparison experiments,a possible MO photodegradation me-chanism for the g-C3N4photocatalysis system was proposed.Experimental SectionThe photocatalyst of g-C3N4was prepared by directly heating melamine in the semiclosed system to prevent sublimation of*Corresponding author.E-mail:zsli@(Z.S.Li).Postal address: NO.22,Hankou Road,Nanjing,Jiangsu210093,P.R.China.Phone number:86-25-83686630.Fax number:86-25-83686632.(1)Fujishima,A.;Rao,T.N.;Tryk,D.A.J.Photochem.Photobiol.C2000 1,1–21.(2)Yamasita,D.;Takata,T.;Hara,M.;Kondo,J.N.;Domen,K.Solid State Ionics2004,172,591–595.(3)Zhang,X.T.;Sato,O.;Taguchi,M.;Einaga,Y.;Murakami,T.;Fujishima,A.Chem.Mater.2005,17,696–700.(4)O0Regan,B.;Gr€a tzel,M.Nature1991,353,737–740.(5)Osterloh,F.E.Chem.Mater.2008,20(1),35–54.(6)Wang,X.C.;Maeda,K.;Thomas,A.;Takanabe,K.;Xin,G.;Carlsson J.M.;Domen,K.;Antonietti,M.Nat.Mater.2009,8,76–80.(7)Wang,X.C.;Chen,X.F.;Thomas,A.;Fu,X.Z.;Antonietti,M.Adv.Mater. 2009,21,1–4.(8)Thomas,A.;Fischer,A.;Goettmann,F.;Antonietti,M.;M€u ller,J.;Schl€o gl, R.;Carlsson,J.M.J.Mater.Chem.2008,18,4893–4908.(9)Komatsu,T.J.Mater.Chem.2001,11,799–801.(10)Zhao,Y.C.;Yu,D.L.;Yanagisawa,O.;Matsugi,K.;Tian,Y.J.Diamond Relat.Mater.2005,14,1700–1704.(11)Ma,H.A.;Jia,X.P.;Chen,L.X.;Zhu,P.W.;Guo,W.L.;Guo,X.B.; Wang,Y.D.;Li,S.Q.;Zou,G.T.;Zhang,G.;Bex,P.J.Phys.:Condens.Matter 2002,14,11269–11273.Article Yan et al.melamine.10g of melamine powder was put into an alumina crucible with a cover,then heated to 500°C in a muffle furnace for 2h at a heating rate of 20°C/min;the further deammonation treatment was performed at 500,520,550,and 580°C for 2h,respectively.The samples were characterized by X-ray diffraction(XRD)for phase identification on the Rigaku RINT2000dif-fractometer.The specific surface area was determined with the Brunauer -Emmett -Teller (BET)equation at 77K by using an adsorption apparatus (Micromeritics TriStar,USA).UV -vis diffuse reflection spectra were measured using a UV -vis spectro-photometer (Varian CARY 100,USA)and converted from reflection to absorbance by the Kubelka -Munk method.Photo-catalytic activity of g-C 3N 4for methyl orange (MO)photode-gradation was evaluated in a Pyrex reactor.0.3g of g-C 3N 4was dispersed in MO aqueous solution (100mL,0.4mg L -1).The light irradiation system contains a 300W Xe lamp with cutoff filter L42for visible light and a water filter to eliminate the temperature effect.Measurement of apparent quantum efficiency for degrad-ing MO over g-C 3N 4was performed by using a monochromatic filter (420nm).The intensity of the corresponding incident light is 9.764μW/cm 2.Results and DiscussionIn order to understand the phase transformation during heat-ing of melamine,the thermal analysis was carried out by using the thermogravimetric -differential scanning calorimetry analysis (TG-DSC).The detected range of temperature is from room temperature to 1000°C at a heating rate of 10°C /min.An alumina crucible with a cover was used during thermal analysis to prevent sublimation of melamine.The DSC and TG thermo-appeared at 545and 630°C,which correspond to the further deammonation process and decomposition of material,respec-tively.Two exothermic reaction peaks are attributed to the disappearance of this material via generation of nitrogen and cyano fragments,exhibiting at 660and 750°C,respectively.The thermal stability and phase transformation of the g-C 3N 4pre-pared at 520°C were detected in an open system,as shown in Figure 1b.It can be seen that the as-prepared g-C 3N 4becomes unstable when the heat temperature is above 600°C,and heating to 750°C results in no residue of the material being observable.The DSC curve shows that decomposition of the as-prepared g-C 3N 4occurred first at 600°C,with the decomposition productsburnt immediately.No deammonation process was observed during heating of g-C 3N pared with the DSC curve of g-C 3N 4,we can confirm that the endothermal peak at 630°C during heating of melamine should be attributed to the decom-position of g-C 3N 4formed in the pyrolysis of melamine,which is 30°C higher than the starting decomposition temperature of as-prepared g-C 3N 4(600°C).This indicates that g-C 3N 4is more stable in the semiclosed ammonia atmosphere than in the open system.On the other hand,two combustion processes were found during heating melamine;however,just one combustion process was observed for heating the g-C 3N 4.The aforementioned evidence can be attributed to the fact that the deammonation process of melamine resulted in an ammonia atmosphere in the semiclosed system,which can improve the stability of g-C 3N 4and restrain combustion of products.The XRD patterns for all the samples are shown in Figure 2.We can see that two peaks are found in all the samples.It is widely accepted to date that the g-C 3N 4is based on tri-s -triazine building blocks.8The strongest peak at 27.41°is a characteristic interlayer stacking peak of aromatic systems,indexed for graphitic materials as the (002)peak.The calculated interplanar distance of aromatic units (d =0.325nm)is significantly smaller than that of the crystalline g-C 3N 4(d =0.34nm).12The dense structure can be attributed to the localization of the electrons and stronger bindingFigure 1.TG-DSC thermograms for heating the melamine (a)and the g-C 3N 4(b)obtained by heating melamine at 520°C.Figure 2.XRD patterns for g-C 3N 4samples obtained by heatingdifferent precursors at various temperatures.(12)Bojdys,M.J.;M €uller,J.O.;Antonietti,M.;Thomas,A.Chem.;Eur.J.2008,14,8177–8182.Yan et al.Articlebetween the layers.The small angle peak at 13.08°,correspondingto interplanar distance of 0.676nm,is indexed as (100),which is associated with interlayer stacking.The distance is slightly below the size of one tris-s -triazine unit (ca.0.73nm),which presumably is attributed to the presence of small tilt angularity in the structure.The Fourier transform infrared (FT-IR)spectra of two kinds of samples are shown in Figure 3.Several strong bands in the 1200-1650cm -1region were found,which correspond to the typical stretching modes of CN heterocycles.13Additionally,the characteristic breathing mode of the triazine units at 801cm -1was observed.It should be noted that the broad bands at around 3000cm -1are indicative of NH stretching vibration modes.12This indicates that the amino functions still existed in the products by directly heating the melamine or cyanamide.The C/N ratios for all samples were determined by elemental analysis on the elemental analyzer (vario EL II,Elementar,Germany).The experimental error in weighing was (0.001mg.For heating melamine at 500,520,550,and 580°C,the C/N ratio of the product is 0.721,0.735,0.737,and 0.742,respectively.It indicates that the C/N ratios increase with increasing condensation tem-perature.However,the C/N ratios for all cases of heating melamine are lower than 0.75for the ideal crystal g-C 3N 4.The results are in agreement with the FT-IR,implying that the amino groups originated from the incomplete condensation of the as-prepared g-C 3N 4.Indeed,as reported,the residual hydrogen atoms bind to the edges of the graphene-like C -N sheet in the form of C-NH 2and 2C-NH bonds.14On the other hand,as we know from DSC observation,the as-prepared g-C 3N 4is unstable above 600°C.The existence of amino groups and the low thermal stability of g-C 3N 4indicate that it is very difficult to lower the hydrogen content by directly heating melamine at ambient pressure.The optical properties of the samples by heating melamine were investigated by UV -vis diffuse reflectance spectroscopy,and the results are shown in Figure 4.The spectrum of the sample of cyanamide treated at 550°C for 4h is also shown for comparison.We can see that absorption edges of the samples obtained from heating melamine shift remarkably to longer wavelengths with increasing heating temperature.The decrease in band gaps of the samples is from 2.8to 2.75eV when the heat treatment tempera-ture is increased from 500to 580°C.It is worth noting that themain absorption of the sample heated at 520°C,which exhibits a band gap of ca.2.75eV,is close to that of the samples heated at 550and 580°C.The spectra of the samples heated at higher temperature,520°C,show a weak absorption tail,especially for the sample of cyanamide heated at 550°C,for which the absorption tail may reach 550nm.This probably is attributed to the structure defects formed in samples treated at the high temperatures,which improve the optical absorption of materials.The photocatalytic activities of all the samples obtained by pyrolysis of melamine were evaluated for methyl orange (MO)photodegradation under visible light (λ>420nm)irradiation,as shown in Figure 5a.The photodegradation of MO over the commercial nitrogen-doped-TiO 2(TPS201,Sumitomo Corp.Japan)(denoted as N-TiO 2)and the sample obtained by heating cyanamide was also given here for comparison.It is well-known that,as a typical organic contaminant,MO is stable under UV -vis irradiation if there is no photocatalyst involved.15,16The absorption spectrum of the homogeneous MO solution without catalyst submitted to illumination with UV -vis light irradiation from a 300W xenon lamp for 5h exhibits almost no difference from the original absorption.We can know that the MO is stable in our experimental conditions.The N-TiO 2possesses a specific surface area (64.8m 2/g)more than eight times higher than that (an average value,ca.8m 2/g)of g-C 3N 4samples;however,it is obvious that photocatalytic activities for all the g-C 3N 4samples are much higher than those of the N-TiO 2.The optical absorption spectrum of N-TiO 2was shown in Figure 4.We can know that the main absorption edge of N-TiO 2is at 390nm,corresponding to the essential light absorption of TiO 2.17The weak absorption tail in the wavelength range 390-480nm originated from the substitutional doping of N,because its p states contribute to narrowing of the band gap by mixing with O 2p states.18The weak light absorption of N-TiO 2means poor visible light response.As a result,N-TiO 2has a low activity for photodegrading MO dye.The g-C 3N 4sample obtained from heating melamine at 520°C (denoted as M520)shows the highest activity,which is the same as that of the sample obtained fromFigure 3.FT-IR spectra for g-C 3N 4fabricated from differentprecursors.Figure 4.UV -vis absorption spectra for commercial N-doped-TiO 2and g-C 3N 4samples obtained by heating the different pre-cursors at different temperatures.(13)Li,X.F.;Zhang,J.;Shen,L.H.;Ma,Y.M.;Lei,W.W.;Cui,Q.L.;Zou G.T.Appl.Phys.A:Mater.Sci.Proc.2009,94,387–392.(14)Zhao,Y.C.;Liu,Z.;Chu,W.G.;Song,L.;Zhang,Z.X.;Yu,D.L.;Tian,Y.J.;Xie,S.S.;Sun,L.F.Adv.Mater.2008,20,1777–1781.(15)Wang,Y.Y.;Zhou,G.W.;Li,T.D.;Qiao,W.T.;Li,mun.2009,10,412–415.(16)Gao,F.;Chen,X.Y.;Yin,K.B.;Dong,S.;Ren,Z.F.;Yuan,F.;Yu,T.;Zou,Z.G.;Liu,J.M.Adv.Mater.2007,19,2889–2892.(17)Rajeshwar,K.;de Tacconi,N.R.;Chenthamarakshan,C.R.Chem.Mater.2001,13(9),2765–2782.(18)Asahi,R.;Morikawa,T.;Ohwaki,T.;Aoki,K.;Taga,Y.Science 2001,293,269–271.Article Yan et al.heating cyanamide at550°C(denoted as C550);the dye of MO is completely degraded after5h visible light irradiation.However, the pathway of MO photodegradation is different for the M520 and C550samples(see Figure S1in the Supporting Information).No light absorption peak shift was observed during degradation of MO over M520sample,indicating that the M520sample can directly mineralize MO without intermediate products.For the C550sample,the main absorption peak of MO gradually shifted to the shorter wavelengths with increasing light irradiation times, implying that the intermediate products were formed during the photodegradation reaction process.In other words,this means that the photooxidation ability of M520is better than that of C550sample.In the UV-visible absorption spectrum of C550, the obvious absorption tail,which resulted from poor thermal stability of g-C3N4,suggests that the high-temperature heat treatment at550°C leads to the decreased photooxidation ability for C550.For the samples of melamine heated at500,550,and 580°C,only89%,78%,and69%MO,respectively,was photo-degraded in the same irradiation time.Indeed,compared with the M520sample,the sample treated at500°C has a low C/N ratio of 0.721;this means that the slightly decreased photocatalytic activity is attributed to the uncompleted condensation.However, there is a big drop in photocatalytic activity for the samples treated at temperatures above520°C.Apparently,increasing the heat temperature will decrease the photooxidation ability of g-C3N4.The C/N ratio,i.e.,the degree of condensation,is inconsistent with the structural integrality.To obtain a samplewith high C/N ratio,a high heat treatment temperature is neededto lower the content of hydrogen in products,which leads todecreased structural integrality for the final product.Indeed,incombination with the elemental analysis and thermal analysisresults discussed above,it is obvious that in the case of g-C3N4preparation by pyrolysis of melamine the degrees of condensationfor the final product increase with increasing heat temperature,but the thermal stability of g-C3N4decreases.This probablyimplies that,in our case of g-C3N4preparation,520°C is anappropriate temperature for obtaining the g-C3N4with goodcrystal structure and moderate degree of condensation,andtherefore,the M520sample exhibits high activity in degradingMO.Furthermore,it is worth pointing out that a one-timeincrease in the rate of MO photodegradation was achieved overthe M520sample under full arc light irradiation;the dye of MOcan be degraded completely after2.5h UV-vis light irradiation.Some active species,such as the hydroxyl radicals(3OH),the superoxide(O23or HOO3),and the holes,are formed during the photodegradation reaction induced by light irradiation.The3OH in aqueous solutions,as the primary oxidant,is generated via thedirect hole oxidation19or photogenerated electron induced multi-step reduction of O2(O2þe f O23,O23þeþ2Hþf H2O2, H2O2þe f3OHþOH-).20Generally,it is confirmed that the generation of superoxide is associated with the photogenerated electron induced direct reduction of O2(O2þe f O23).In addition,the photogenerated hole can directly react with organic compounds if the semiconductor photocatalyst has moderate redox potential.For these active species,hydroxyl radical reac-tions are nonselective and will virtually react with almost all the organic compounds by either H-atom abstraction,direct electron transfer,or insertion.In order to investigate the possible photodegradation mechan-ism of MO over g-C3N4semiconductor,several comparisonexperiments were performed,and the results were shown inpared with photodegradation of the pure MO/g-C3N4solution,we can know that no change in the rate of MOphotodegradation is observed when methanol(10vol%)wasadded as a sacrificial hole acceptor.This implies that the photo-generated hole is not an effective active species during degradingMO over g-C3N4;this reaction is not attributed to the direct holeoxidation.Indeed,as reported by Wang et al.,6the oxidation levelfor water splitting is located slightly above the top of the valenceband of g-C3N4,which would permit transfer of holes,but with alow driving force.This suggests that the low driving force is notbeneficial for the hole reactions in aqueous solution system.However,there is a big increase in rate of MO photodegradationwhen Ag particles(5wt%)were loaded onto the g-C3N4surfaceusing the photodeposition method;21the MO can be degradedcompletely after1h visible light irradiation,which is5times fasterthan that over the bare g-C3N4.A further investigation,the effectof O2on photodegradation of MO,was preformed in argonatmosphere.The reaction setup was vacuum-treated several timesin order to eliminate O2,and then,high-purity argon gas(purity,99.999%)was followed into the reaction setup for obtainingambient pressure.After5h visible light irradiation,only43%MOwas photodegraded in the absence of O2(see Figure S2inSupporting Information).It means that O2is a main factor forMO photodegradation over the g-C3N4photocatalyst,whichaffects the formation of superoxide via direct reduction of O2(19)Yoon,S.H.;Lee,J.Environ.Sci.Technol.2005,39,9695–9701.(20)Liu,G.G.;Li,X.Z.;Zhao,J.C.;Horikoshi,S.;Hidaka,H.J.Mol.Catal. A:Chem.2000,153,221–229.(21)Tada,H.;Ishida,T.;Takao,A.;Ito,ngmuir2004,20,7898–7900.Yan et al.Articleand hydroxyl radicals via multistep reduction of O2.A valuablefact is that,if the strong acid radical ion,such as SO42-(0.01M)or NO3-(0.01M),was introduced into the aqueous MO/g-C3N4solutions,the MO degradation is significantly accelerated,andthe reaction was completed after80min visible light irradiation.Clearly,the improved reaction activity is due to the introductionof a strong acid radical ion,which increases the Hþconcentrationand therefore accelerates the reaction of O23þeþ2Hþf H2O2, further accelerating the formation of hydroxyl radicals via multi-step reduction of O2.The experimental fact suggests that g-C3N4photocatalyst possesses good environmental adaptability,whichcan directly apply to industrial wastewater treatment to degradeorganic pollutants.On the basis of the aforementioned evidence,we are inclined to believe that for the MO photodegradation overg-C3N4the photocatalytic activity has mainly resulted from activespecies which originated from photogenerated electron inducedreduction of O2.For practical application of the photocatalyst,the stability during photoreaction was a crucial factor.Ourstability test indicates that no decrease in photocatalytic activitywas observed in the MO photodegradation reaction that wasrepeated three times(see Figure S5in Supporting Information).The XRD pattern of the as-prepared g-C3N4is similar to thatof the sample after reaction(see Figure S6,in SupportingInformation),meaning that the g-C3N4is stable in the photo-reaction.The apparent quantum efficiency is a criterion toevaluate photocatalytic activity of a given material.For MOdegradation,taking into account a single electron process,22theapparent quantum efficiency(denoted as E Q)for degrading MOwas defined by E Q=N nup/N nip,where N nup and N nip representthe number of used photons and the number of incident photons,respectively.It is assumed that all incident photons are absorbedby the photocatalyst.The calculated value of E Q at420nm is 1.5%,implying that the low-cost g-C3N4has potential in water purification due to its good photodegradation performance and environmental applicability.SummaryIn summary,we have successfully fabricated the g-C3N4 photocatalyst by directly heating melamine.The stable MO dye was selected as a degrading goal to evaluate the photocatalytic activity of g-C3N4.Our results clearly indicate that the metal-free g-C3N4has good performance in the photooxidation of organic pollutant.For the typical MO dye photodegradation,the photo-catalytic avtivity of g-C3N4can be improved significantly when Ag is used as a cocatalyst.This means that g-C3N4is a promising material possessing a good potential in photocatalytic application fields if some techniques,such as loading cocatalyst and doping, are used to improve its photocatalytic activity.Our comparison studies showed that the photodegradation activity of MO over g-C3N4is mainly attributed to the generation of active species induced by photogenerated electrons.Moreover,the g-C3N4 photocatalyst showed good photocatalytic activity in the presence of a strong acid radical ion;this further indicates that it is feasible to apply the g-C3N4with low cost and facile synthesis to treat industrial wastewater containing organic pollutants. Acknowledgment.This work is supported by the National Natural Science Foundation of China(no.20528302),the Na-tional Basic Research Program of China(973program, 2007CB613301and2007CB613305).Supporting Information Available:UV-visible spectro-scopic changes for MO degradation,XRD and SEM for Ag-modified g-C3N4,and the stability test for g-C3N4.This material is available free of charge via the Internet at http:// .(22)Bandara,J.;Morrison,C.;Kiwi,j.;Pulgarin,C.;Peringer,P.J.Photochem. Photobiol.A1996,99,57–66.。
光伏行业英文词汇
太阳电池solar cell通常是指将太阳光能直接转换成电能的一种器件。
硅太阳电池silicon solar cell硅太阳电池是以硅为基体材料的太阳电池。
单晶硅太阳电池single crystalline silicon solar cell单晶硅太阳电池是以单晶硅为基体材料的太阳电池。
非晶硅太阳电池（a—si太阳电池）amorphous silicon solar cell用非晶硅材料及其合金制造的太阳电池称为非晶硅太阳电池，亦称无定形硅太阳电池，简称a—si太阳电池。
多晶硅太阳电池polycrystalline silicon solar cell多晶硅太阳电池是以多晶硅为基体材料的太阳电池。
聚光太阳电池组件photovoltaic concentrator module？系指组成聚光太阳电池，方阵的中间组合体，由聚光器、太阳电池、散热器、互连引线和壳体等组成。
电池温度cell temperature系指太阳电池中P-n结的温度。
太阳电池组件表面温度solar cell module surface temperature系指太阳电池组件背表面的温度。
大气质量（AM）Air Mass (AM)直射阳光光束透过大气层所通过的路程，以直射太阳光束从天顶到达海平面所通过的路程的倍数来表示。
太阳高度角solar太阳高度角solar elevation angle太阳光线与观测点处水平面的夹角，称为该观测点的太阳高度角。
辐照度irradiance系指照射到单位表面积上的辐射功率（W/m2）。
总辐照（总的太阳辐照）total irradiation (total insolation)在一段规定的时间内，（根据具体情况而定为每小时，每天、每周、每月、每年）照射到某个倾斜表面的单位面积上的太阳辐照。
直射辐照度direct irradiance照射到单位面积上的，来自太阳圆盘及其周围对照射点所张的圆锥半顶角为8o的天空辐射功率。
高钛渣提钛制备纳米二氧化钛及其光催化性能的研究
第49卷第9期2021年5月广州化工Guangzhou Chemical IndustryVol. 49 No. 9May. 2021高钛渣提钛制备纳米二氧化钛及其光催化性能的研究**基金项目：沈阳医学院科技发展基金(No ： 20191026) ； 2019辽宁省教育厅科学研究一般项目(N 。
： 201902)；沈阳医学院创新创业训练计划(N 。
： 20209034)D通讯作者：王凯(1978-),女，讲师，主要从事纳米材料光催化性能研究。
王小禾，王 凯，隋丽丽，董微，常红，吴 園，莫大森(沈阳医学院，辽宁沈阳110034)摘 要：以高钛渣为原料，采用浓硫酸焙烧法得到硫酸氧钛溶液，水热法制备偏钛酸进行高温锻烧，制备不同晶型组成的纳米二氧化钛产品，以亚甲基蓝为降解对象，检测不同熾烧温度下纳米二氧化钛产品的光催化性能。
在254 nm 波长的光照下，对亚甲基蓝溶液的光催化降解实验结果表明：纳米Ti()2对亚甲基蓝有一定的降解活性，650 t 锻烧得到的二氧化钛产品对亚甲基蓝 的光催化降解活性最高。
关键词：高钛渣；二氧化钛；光催化；亚甲基蓝中图分类号： X52文献标志码：A 文章编号：1001 -9677(2021)09-0064-03Photocatalytic Performance of Nanometer TiO 2 Preparedfrom High Titanium Slag *WANGXiao-he, WANG Kai, SUI Li-li, DONG Wei, CHANG Hong, WU Nan, MO Da-sen(Shenyang Medical College , Liaoning Shenyang 110034, China)Abstract : Using high titanium slag as raw material , titanium oxysulfate solution was obtained by roasting withconcentrated sulfuric acid. Metatitanic acid was prepared by hydrothermal method and calcined at high temperature toprepare nanotitanium dioxide products with different crystal form& The photocatalytic activity was tested of nano titanium dioxide products with different calcination temperatures and methylene blue as degradation object. The photocatalyticdegradation under UV irradiation at k = 254 nm showed thatnano TiO 2 had a certain degradation activity to Methylene blue. The photocatalytic activity of titanium dioxide products calcined at 650 P was the highest.Key words ： high titanium slag ； titanium dioxide ； photocatalysis ； methylene blueTiOz 具有廉价、稳定、无毒、光催化活性较高等特点，被广泛应用于有机污染物的降解。
建筑建设相关词汇翻译(3)
建筑建设相关词汇翻译(3)建筑建设相关词汇翻译(3)建筑建设相关词汇翻译(3)装饰玻璃decorative glazing夹层玻璃laminated glass特种玻璃special function glass镜子mirrors有机玻璃plastic glazing装玻璃用附件glazing accessories玻璃薄膜glazing film幕墙glazed curtain walls金属结构幕墙metal framed curtain wall半透明墙和屋顶组合件translucent wall roof assemblies结构玻璃幕墙structural glass curtain walls轻质板材light board龙骨系统matel support assemblies非承重墙体龙骨non-load-bearing wall framing顶棚悬吊体系ceiling suspension成套内部骨架interior framing assemblies灰浆和石膏板plaster gypsum board石膏板，骨架及附件gypsum board, framing accessories面砖tiles瓷砖ceramic tile玻璃玛赛克glass mosaics装饰石材terrazzo预制水磨石制品precast terrazzo吊顶ceiling吸声吊顶acoustical ceilings金属吊顶metal ceilings轻质吊顶light-transmitting ceilings地面装饰砖石地面masonry flooring木地面wood flooring弹性地面resilient flooring抗静电地面static control flooring地毯地面carpet地毯块carpet tile墙面装饰wall finishes墙面装饰面层wall coverings柔性木墙板flexible wood sheets隔(吸)音绝缘和嵌缝材料acoustical insulation and sealants 油漆及涂料paintings and coatings涂料paints着色及透明面层stains and transparent finishes装饰面层decorative finishes高性能面层high-performance coatings阻燃面层fire-retardant coatings防化学腐蚀涂料chemical resistant coatings面层胶粘剂finish adhesives厕所隔断10155-toilet compartments通风和排气口10200-louvers and vents壁炉和火炉fireplaces and stoves指示装置identifying devices指示牌和公告板10410-directories bulletin boards锁lockers锁和附件10501-locker accessories locks遮阳（雨）篷10536-awnings隔断partitioins钢丝网隔墙10605-wire mesh partitions可拆卸隔墙10615-demountable partitions活动隔墙，屏网和隔板10630-portable partitions, screens panels采光板10730-daylighting panels壁柜和衣橱专用制品wardrobe and closet specialties衣帽架及附件10914-hat coat racks accessories装饰织物fabrics工艺品artwork建筑古玩architectural antiques中国古建筑装饰材料碧饰、壁画murals墙面装饰品wall decorations雕刻或雕塑/浮雕饰品carved or cast sculpture/relief artwork玻璃艺术制品art glass箱，柜及台架制品manufactured casework实验室台柜laboratory casework展示台柜display casework室内用品及附件furniture accessories遮阳板和窗帘blinds, shades shutters帷幔和窗帘五金drapery curtain hardware电动控制五金-用于百叶、帷幕及窗帘motorized hardware-blinds，shades，draperies家具furniture敞开式办公系统open office systems办公室家具office furniture座椅seating室外家具outdoor furniture住宅家具residential furniture固定家具fixede furniture座椅及桌子配件seat and table accessories特殊用途装饰品special use/decorative furnishings单元房屋13020-building modules特殊用途房间13030-special purpose rooms健身房13032-athletic rooms桑拿浴及设备saunas equipment蒸气浴及设备steam baths equipment整体浴室13058-bathroom modules整体厨房13060-kitchen modules预加工房屋13121-pre-engineered buildings活动房屋13136-portable mobile buildings预制住宅结构13144-prefabricated residential structures预加工停车场结构13148-pre-engineered parking structures游泳池及设备13152-swimming pools equipment液体和气体储罐liquid and gas storage tanks指示器、记录器及控制器13440-indicators,recorders and controllers太阳能系统13602-solar energy systems平板式太阳能收集器solar flat plate collectors保安通道和监视系统security access survillance 建筑建设相关词汇翻译(3) 相关内容:。
纳米技术运用到生活方面写一篇英语作文
纳米技术运用到生活方面写一篇英语作文全文共3篇示例，供读者参考篇1The Nanotech Revolution: How Tiny Particles Are Transforming Our Daily LivesNanotechnology sounds like something out of a science fiction movie - the ability to manipulate and control individual atoms and molecules. However, this cutting-edge field of applied science has gone mainstream and is rapidly changing the world around us in profound ways. As a student studying nanotechnology, I've become fascinated by its vast potential to revolutionize everything from electronics and energy production to healthcare and environmental protection.At its core, nanotechnology involves materials, devices, or other structures with at least one dimension sized from 1 to 100 nanometers. A nanometer is one-billionth of a meter - unimaginably small. To put that scale into perspective, a single strand of human DNA is around 2.5 nanometers wide. Working at the nanoscale allows scientists and engineers to leverage theunique physical, chemical, and biological properties of materials in this tiny realm.While nanotechnology may seem abstract, its impacts are extremely tangible in our everyday lives as consumers. One of the earliest commercial applications has been in the electronics sector through transistors, memory chips, and processors constructed with nanoparticles. This nano-engineering has enabled the relentless miniaturization of electronics and incredible increases in computing power aligned with Moore's Law over recent decades.Chances are the smartphone, laptop, or other device you're viewing this on contains nanomaterials and components. However, nanotech's influence extends far beyond modern gadgets. It is being infused into household goods like food containers designed with nanocomposites to keep contents fresher for longer. Some plastic storage products utilize nanoparticles that destroy microbes, acting as antimicrobials.The apparel industry has enthusiastically embraced nanotechnology as well. Nanofibers and nanowhiskers enhance the strength of fabrics while providing stain resistance, water repellency, and wrinkle-free properties. From dress shirts to athletic wear, nanotechnology is making our clothes performbetter and last longer. Feet clad in socks woven with nanoparticles even benefit from odor control.In our homes, nanotech is being applied to improve insulation, make cleaning products moreenvironmentally-friendly yet powerful, and construct stronger, lighter components for appliances, furniture, and other goods. Windows, paints, and tiles can be coated with nanoparticle films to become self-cleaning by making surfaces hydrophobic so water easily rinses away dirt. Nanostructured materials have also enabled more energy-efficient lighting such as LED bulbs.The beauty and personal care industry may be one of the biggest adopters of nanotechnology. From cosmetics and sunscreens to anti-aging creams and hair products, nanoparticles are enhancing product efficacy and performance. For instance, using nanosized zinc oxide and titanium dioxide enables transparent sunblock formulations that block ultraviolet rays yet remain invisible on the skin. Nanoparticles of minerals can also improve the look and feel of make-up while providing longer-lasting coverage.Beyond the cosmetic benefits, some nanoparticles function as antioxidants and anti-inflammatories. Scientists are investigating anti-aging skin care treatments that utilizenanocarriers to transport antioxidants deeper into the epidermis layer of the skin. Dendrimers and nanoemulsions are two emerging classes of nanoparticles being explored for targeted drug delivery through the skin's barrier.Stepping outside the home, nanotechnology is impacting modern automobiles and transportation systems. Nanocomposites have enabled manufacturers to produce stronger, lighter vehicle bodies and components to improve fuel efficiency. Tires with nanofillers roll with less resistance, also boosting gas mileage. Nanocoatings applied to automotive glass and ceramic surfaces make them hydrophobic and resistant to fogging. Looking ahead, innovators are developing nanostructured batteries and fuel cells with higher energy density for electric vehicles.While the consumer-oriented applications are remarkable, nanotechnology is poised to transform many other vital sectors that touch our lives. Nanomedicine is an exciting field harnessing nanodevices for advanced disease diagnosis and targeted drug delivery with precise spatial and temporal control. Researchers envision fleets of nanorobots one day being able tonon-invasively screen for diseases, deliver therapeutic agents, and even perform microscopic surgery.Advanced nanomaterials and nanoengineered surfaces are being developed to radically improve water purification systems, catalysis, and sensing for environmental monitoring and remediation. The unique properties of nanoparticles allow capture of contaminants and reactions to occur much more efficiently. Innovations in nanotech membranes and filters can desalinate water with considerably less energy than conventional methods.In the energy sector, nanostructured photovoltaics, fuel cells, and thermoelectrics could provide cleaner power generation solutions. Utilities companies are exploring nanocomposite coatings for shipping and storing natural gas. The oil and gas industry is investigating applications of nanotechnology for enhanced exploration, drilling, and refining processes. Some areas I'm particularly interested in are zero-emission nanocomposite batteries and ultracapacitors for electric vehicles and energy storage.Admittedly, some risks of nanotechnology in consumer products raise reasonable concerns around human and environmental impact, requiring further study. Cosmetic products that contain nanoparticles and don't label them properly have sparked backlash. There are also debates aroundethical implications of nanobiotechnology applications. However, advocates emphasize nanotech enables highly efficient use of raw materials and production processes, promising more sustainable practices overall.Numerous agencies, companies, universities, and other organizations are diligently working to assess and mitigate potential risks while responsibly advancing the capabilities of nanotechnology. Regulatory frameworks and safety guidelines are being established. As a student, I believe education and public dialogue will be crucial for responsible development of nanotechnology to ensure it progresses safely while unlocking its tremendous societal benefits.In conclusion, nanotechnology is proving to be one of the most transformative and cross-cutting fields in modern science. From shattering the limits of industrial manufacturing and computing to enabling breakthrough products that improve our health and quality of living, nanotech's mind-boggling innovations are rapidly permeating nearly every aspect of our lives. While challenges remain, the future possibilities are as enormous as the nanoscale itself. For students like myself, it's an incredibly exciting time to study and help shape this nanorevolution.篇2The Nanotech Revolution: How Tiny Particles Are Transforming Our LivesNanotechnology is often viewed as an abstract scientific concept that doesn't impact our everyday lives. However, the reality is that this incredible technology involving the manipulation of matter at the atomic and molecular scale has already seeped into many aspects of modern society. From the clothes we wear to the food we eat, nanotechnology is revolutionizing various industries and changing the world in subtle yet profound ways.As a student fascinated by science and technology, I have been intrigued by the vast potential of nanotechnology and its ability to solve real-world problems. In this essay, I will explore some of the most exciting applications of nanotechnology in our daily lives, showcasing how this cutting-edge field is making our world better, safer, and more efficient.One of the most significant areas where nanotechnology has made its mark is in the realm of textiles and clothing. Nanoparticles are being incorporated into fabrics to create stain-resistant, water-repellent, and wrinkle-free materials. These"smart fabrics" are not only more durable and easier to maintain, but they also have the potential to regulate body temperature, provide UV protection, and even monitor vital signs. Imagine wearing a shirt that can adjust its insulation based on the weather conditions or a sports jersey that can track your heart rate and hydration levels during a workout!Another area where nanotechnology is making waves is in the field of food production and packaging. Nanoparticles are being used to develop more effective food packaging that can extend the shelf life of perishable items, reduce spoilage, and even detect the presence of harmful bacteria or pathogens. Additionally, nanomaterials are being explored for their potential to enhance the nutritional value of foods, improve food safety, and increase crop yields through more efficient delivery of nutrients and pesticides.In the realm of consumer electronics, nanotechnology is enabling the development of smaller, more powerful, and energy-efficient devices. Nanostructured materials are being used to create flexible and transparent displays, high-capacity batteries, and more efficient solar cells. Imagine having a smartphone with a foldable display that fits in your pocket or alaptop that can run for days on a single charge thanks to its nanotech-enhanced battery.Nanotechnology is also making significant strides in the field of medicine and healthcare. Nanoparticles are being used to develop targeted drug delivery systems that can precisely transport medications to specific areas of the body, reducing side effects and increasing efficacy. Nanobiosensors are being developed to detect diseases at an early stage, enabling more timely and effective treatment. Furthermore, nanomaterials are being explored for their potential to regenerate tissue, create artificial organs, and even deliver gene therapy more efficiently.Beyond these applications, nanotechnology is also playing a crucial role in addressing environmental challenges. Nanostructured membranes are being used to purify water and remove pollutants more efficiently, while nanoparticles are being employed in air filters and catalytic converters to reduce air pollution. Additionally, nanotechnology is being explored for its potential to create more efficient and cost-effective renewable energy sources, such as solar cells and fuel cells.However, it is important to acknowledge that nanotechnology, like any emerging technology, also comes with potential risks and challenges. There are concerns about thepotential toxicity and environmental impact of certain nanomaterials, as well as questions about the long-term health effects of exposure to nanoparticles. Additionally, there are ethical considerations surrounding the use of nanotechnology in areas such as human enhancement, surveillance, and weaponry.Despite these concerns, the potential benefits of nanotechnology are too significant to ignore. As a student, I am excited about the prospect of being part of a generation that will witness the full realization of this revolutionary technology. I believe that with proper regulation, research, and ethical guidelines, nanotechnology can be harnessed to create a better, more sustainable, and more prosperous world for all.In conclusion, nanotechnology is no longer a futuristic concept; it is a reality that is transforming our lives in ways both visible and invisible. From the clothes we wear to the food we eat, from the devices we use to the medical treatments we receive, nanotechnology is making our world smarter, more efficient, and more advanced. As a student, I am eager to be a part of this nanotech revolution and contribute to the development of this incredible technology that has the potential to solve some of the world's most pressing challenges.篇3The Nanotech Revolution: How Tiny Particles Are Transforming Our WorldAs students, we're constantly bombarded with new technological terms and buzzwords that can be tough to grasp. One concept that has been generating a lot of excitement in recent years is nanotechnology. But what exactly is it, and how is it impacting our daily lives? That's what I aim to explore in this essay.At its core, nanotechnology refers to the manipulation and control of matter on an incredibly small scale – we're talking about materials measured in nanometers, or billionths of a meter. To put that into perspective, a single sheet of paper is about 100,000 nanometers thick! By working at this minuscule level, scientists and engineers can create innovative materials, devices, and products with unique and enhanced properties.Now, you might be thinking, "That's all well and good, but how does nanotechnology actually affect me?" Well, let me tell you – the applications of this cutting-edge field are already all around us, and they're only going to become more prevalent in the years to come.Let's start with something we all use every day: our gadgets and electronics. Nanotechnology is playing a crucial role inmaking our devices smaller, faster, and more energy-efficient. For example, the processors in our computers and smartphones rely on tiny transistors and circuits that are now being manufactured at the nanoscale. This allows for more compact designs without sacrificing performance.But it's not just about cramming more components into a smaller space. Nanotech is also enhancing the capabilities of our devices in exciting ways. Take the screens on our phones and laptops, for instance. Manufacturers are incorporating nanoparticles into display coatings to improve brightness, contrast, and energy efficiency. Some models even featureself-cleaning coatings that use nanomaterials to repel dirt and fingerprints.Speaking of cleaning, nanotechnology is revolutionizing the way we keep our homes and surroundings tidy. Nanotech-based fabrics and surfaces are being developed that can actively repel stains, odors, and bacteria. Imagine having a shirt or a couch that never gets dirty or smelly – that's the kind of magic nanotechnology promises!But the applications go far beyond just making our lives more convenient. Nanotechnology is also playing a vital role inaddressing some of the world's most pressing challenges, such as healthcare and environmental sustainability.In the medical field, researchers are exploring the use of nanoparticles for targeted drug delivery, where medications can be transported directly to diseased cells or tissues, reducing side effects and improving efficacy. Nanotech-based biosensors are also being developed that can detect diseases like cancer at their earliest stages, allowing for timely treatment and better outcomes.When it comes to the environment, nanotechnology is offering innovative solutions for clean energy production, water purification, and waste remediation. For instance, nanostructured materials are being used to create highly efficient solar cells and batteries, while nanomembranes can filter out contaminants from water sources with unprecedented precision.And that's just the tip of the iceberg! Nanotechnology is also making waves in fields as diverse as agriculture, construction, and even space exploration. Researchers are developing nanoparticle-based pesticides and fertilizers that can be more effective and environmentally friendly. Nanocomposites are being used to create stronger, lighter, and more durable buildingmaterials. And NASA is exploring the use of nanotech for everything from self-cleaning spacesuits to advanced propulsion systems.Of course, like any revolutionary technology, nanotechnology comes with its own set of concerns and challenges. There are legitimate questions about the potential health and environmental risks of nanomaterials, as well as ethical considerations around their use in certain applications (like human enhancement or military applications).But rather than shying away from these challenges, it's important that we, as students and future leaders, engage with these issues head-on. We need to support continued research into the safety and ethical implications of nanotechnology, while also fostering public education and dialogue around this complex topic.At the end of the day, nanotechnology represents a transformative force that has the potential to reshape virtually every aspect of our lives. From the devices we use to the medicines we take, from the clothes we wear to the buildings we live and work in – the nanotech revolution is already underway, and it's up to us to shape its trajectory.So, embrace your curiosity, stay informed, and get excited about the possibilities that nanotechnology holds. Who knows? Maybe one day, you'll be the one developing the next big nanotech breakthrough that changes the world.After all, when it comes to innovation, sometimes the smallest things can have the biggest impact.。
节能家居秀的英语作文
Energy conservation has become an increasingly important topic in our daily lives, and applying this concept to our homes is a practical and effective way to contribute to environmental sustainability.Here is an essay on energyefficient homes that highlights the various ways we can make our living spaces more ecofriendly.Title:The Essence of EnergyEfficient HomesIn the modern era,where environmental concerns are at the forefront of global discussions,the concept of energyefficient homes has gained significant traction.These homes are designed to minimize energy consumption and reduce environmental impact, all while ensuring the comfort and convenience of the occupants.Design and ConstructionThe foundation of an energyefficient home lies in its design and construction.Insulation is a critical component,as it helps to maintain a stable indoor temperature by reducing heat transfer.Highquality insulation materials,such as spray foam or cellulose,are used to seal gaps and prevent drafts.This not only conserves energy but also enhances the homes overall thermal performance.Windows and DoorsWindows and doors are often the weak points in a homes energy envelope. Energyefficient windows are double or tripleglazed and equipped with lowemissivity LowE coatings that reflect heat back into the home during the winter and keep it out during the summer.Doors,especially exterior ones,are wellsealed and insulated to prevent heat loss.Heating and Cooling SystemsThe choice of heating and cooling systems is another key aspect of energy efficiency. Highefficiency HVAC systems,such as geothermal heat pumps or solarpowered air conditioners,are becoming more popular due to their minimal environmental impact and reduced energy consumption.Programmable thermostats further optimize energy use by automatically adjusting temperatures based on occupancy patterns.Renewable Energy SourcesIncorporating renewable energy sources is a significant step towards achieving an energyefficient home.Solar panels,wind turbines,and solar water heaters are examplesof technologies that harness natural resources to generate electricity and heat water, reducing reliance on fossil fuels.Appliances and LightingEnergyefficient appliances and lighting also play a crucial role in conserving energy. Appliances with the ENERGY STAR label consume less electricity and water,while LED and CFL lighting options use a fraction of the energy compared to traditional incandescent bulbs.Water ConservationWater is another resource that energyefficient homes aim to conserve.Lowflow faucets, showerheads,and toilets reduce water usage without compromising performance. Additionally,rainwater harvesting systems and greywater recycling can significantly cut down on water consumption.LandscapingThe landscaping around an energyefficient home is also designed with conservation in mind.Native plants that require less watering and maintenance are preferred,and trees are strategically placed to provide shade and reduce the need for air conditioning. Inhabitant BehaviorFinally,the behavior of the homes occupants is a vital factor in energy efficiency.Simple practices such as turning off lights when not in use,unplugging electronics,and using natural light whenever possible can make a significant difference.ConclusionEnergyefficient homes are not just a trend but a necessity for our future.They represent a commitment to sustainability and a smarter way of living.By adopting these practices, we can reduce our carbon footprint,save on energy bills,and contribute to a healthier planet for generations to come.。
日照强度的英语
日照强度的英语Sunlight IntensityThe sun's rays are a powerful and essential component of our natural world, providing the energy that sustains life on Earth. The intensity of sunlight, or the amount of solar radiation that reaches a given area, is a crucial factor in numerous natural processes and human activities. Understanding the dynamics of sunlight intensity is crucial for a wide range of fields, from agriculture and renewable energy to human health and environmental science.One of the primary factors that influence sunlight intensity is the angle of the sun's rays relative to the Earth's surface. When the sun is directly overhead, its rays strike the Earth's surface at a perpendicular angle, resulting in the highest possible intensity of sunlight. As the sun moves lower in the sky, the angle of the rays becomes more oblique, and the intensity of the sunlight decreases. This phenomenon is particularly noticeable during the changing seasons, as the sun's position in the sky varies throughout the year.The position of the sun in the sky is determined by the Earth's rotation and its orbit around the sun. As the Earth rotates on its axis,different parts of the planet experience day and night, with the sun's rays striking the surface at different angles. Additionally, the Earth's tilt on its axis, which is responsible for the seasons, also affects the angle of the sun's rays and the resulting sunlight intensity.Another factor that influences sunlight intensity is the presence of atmospheric conditions, such as clouds, dust, and water vapor. These elements can scatter, absorb, or reflect the sun's rays, reducing the amount of solar radiation that reaches the Earth's surface. Cloudy days, for example, typically experience lower sunlight intensity than clear, sunny days, as the clouds block and scatter the sun's rays.The intensity of sunlight also varies with geographic location and altitude. In general, areas closer to the equator receive more direct sunlight and higher overall intensity, while regions closer to the poles experience lower sunlight intensity due to the more oblique angle of the sun's rays. Similarly, higher-altitude locations tend to have greater sunlight intensity than lower-altitude areas, as there is less atmospheric interference.The impact of sunlight intensity on various aspects of life is significant and far-reaching. In the field of agriculture, for instance, the intensity of sunlight plays a crucial role in plant growth and development. Photosynthesis, the process by which plants convert light energy into chemical energy, is directly dependent on theavailability and intensity of sunlight. Farmers and horticulturists must carefully consider sunlight intensity when selecting crop varieties, planning planting schedules, and implementing irrigation and shading strategies.In the realm of renewable energy, the intensity of sunlight is a key factor in the efficiency and viability of solar power technologies. Solar panels, which convert the sun's energy into electricity, are highly dependent on the available sunlight intensity. Areas with consistently high sunlight intensity are ideal locations for large-scale solar power generation, as the increased energy output can make these projects more economically viable.The impact of sunlight intensity on human health is also significant. Exposure to sunlight is essential for the production of vitamin D, which plays a crucial role in bone health and immune system function. However, excessive exposure to ultraviolet (UV) radiation, a component of sunlight, can also lead to skin damage and an increased risk of skin cancer. Understanding the optimal levels of sunlight exposure and the factors that influence it is essential for promoting human health and well-being.In the field of environmental science, sunlight intensity is a crucial variable in the study of various natural processes. The intensity of sunlight can affect the temperature and humidity of an area, which inturn can influence the distribution and behavior of plant and animal species. Additionally, sunlight intensity plays a role in the photochemical reactions that drive the formation of air pollutants, such as ground-level ozone, and the degradation of certain environmental contaminants.In conclusion, the intensity of sunlight is a complex and multifaceted phenomenon that has a profound impact on our natural world and human activities. Understanding the factors that influence sunlight intensity, and the ways in which it affects various aspects of life, is crucial for making informed decisions and developing effective strategies in a wide range of fields. As we continue to explore and harness the power of the sun, the study of sunlight intensity will remain a critical area of research and exploration.。
美标专车专用膜
施工簡單,省時省錢
The construction is simple, save time and moneyThe films don ' t require cutting and baking, as well as high-level technicians. 太陽膜不需要切割和烘焙，以及高级技术人员 generally costs about two hours, thus it is complained by many customers, and increases store service costs 防爆膜通常施工時間需两个小时，常因此被许多客户抱怨，且大幅增加服务成本 To mounting films on a car costs two hours. In hot days, more orders, hot work environment, and high labor intensity may impact and destabilize technician ' s operation level, and cause disoperation. 汽车安装防爆膜需要花费两个小时。在炎热的氣候，大量的订单，高溫的工作环 境和高強度劳动力，不稳定的操作環境会影响品質和技师，造成侵害。
“十二五”有关光伏产业的翻译
“十二五”有关光伏产业的翻译1.“十一五”期间，我国太阳能电池产量以超过100%的年均增长率快速发展。
2007-2010年连续四年产量世界第一，2010年太阳能电池产量约为10GW，占全球总产量的50%。
我国太阳能电池产品90%以上出口，2010年出口额达到202亿美元。
General:During the 11th Five-Year-Plan, average annual growth rate of Chinese solar cells productio is more than 100 percent. The country’s output ranked first in the world for four consecutive years, from 2007 to 2010. The country's total output reached 10 GW in 2010, accounting for half of global production. However, more than 90% of the products are exported. The value of export reached $20.2 billion in 2010.2. “十一五”末期，我国晶硅电池占太阳能电池总产量的95%以上。
太阳能电池产品质量逐年提升，尤其是在转换效率方面，骨干企业产品性能增长较快，单晶硅太阳能电池转换效率达到17-19%，多晶硅太阳能电池转换效率为15-17%，薄膜等新型电池转换效率约为6-8%。
At the end of the 11th Five-Year-Plan, the total output of crystalline silicon cells is account for more than 95% of the total output of solar cells in China. The quality of solar cells products increased year by year, especially in conversion efficiency. Leading enterprises product performance is improving rapidly, the conversion efficiency of monocrystalline silicon cells reached 17%-19%. The conversion efficiency of polycrystalline silicon cells reached 15%-17%, the conversion efficiency of thin film and other new types cells are about 6%-8%.3. “十二五”期间，光伏产业保持平稳较快增长，多晶硅、太阳能电池等产品适应国家可再生能源发展规划确定的装机容量要求，同时积极满足国际市场发展需要。
正钛酸丁酯水解粘度控制
2002 年10月The Chinese Journal of Process Engineering Oct. 2002Ti(OC4H9)4水解过程的粘度控制曾贤成，侯立松(中国科学院上海光学精密机械研究所，上海 201800)摘要：报道了用溶胶-凝胶法制备二氧化钛薄膜过程中钛酸丁酯[Ti(OC4H9)4]水解特性的研究结果，给出了体系的酸碱度(酸催化或者碱催化)、添加乙酰丙酮(AcAc)和硝酸银(AgNO3)对Ti(OC4H9)4−C2H5OH−H2O体系粘度变化和凝胶化时间的影响，发现AgNO3对该体系溶胶有非常明显的稳定作用.关键词：Ti(OC4H9)4；水解；粘度；二氧化钛薄膜中图分类号：TB43; TB321 文献标识码：A 文章编号：1009−606X(2002)05−0435−041 前言在多相光催化反应所应用的半导体催化剂中，二氧化钛以其无毒、催化活性高、稳定性好及抗氧化能力强等优点而备受青睐. 但二氧化钛的禁带宽度较大，对太阳能转化为电能的利用率仅为7.1%∼7.9%[1]. 各国科学家对如何提高TiO2的光催化活性进行了大量卓有成效的研究工作.目前，制备二氧化钛的方法有气相法、固相法和液相法. 其中，液相法又包括溶胶−凝胶法、化学沉淀法、水热法、微乳法等[2−4]. 溶胶−凝胶工艺是20世纪70年代活跃起来的一种独特的陶瓷材料合成工艺，它在薄膜、超细粉、纤维、高熔点玻璃制备方面得到了广泛的应用.采用溶胶−凝胶方法制备二氧化钛薄膜时，控制溶液的粘度显得尤其重要. 不但要求粘度达到一定的数值，以便能够制得一定厚度的薄膜，而且要求镀膜时的溶胶粘度在较长时间内稳定，以保证镀膜工艺参数的良好重现性. 钛酸丁酯水解速度很快，极易生成沉淀物，导致使用溶胶−凝胶法失败，无法制备高质量的薄膜. 乙酰丙酮能够与钛酸丁酯形成络合物，从而大大降低其水解速度. 添加适量的乙酰丙酮可以避免沉淀的发生，这方面已经有大量的文献报道[5−7]. 本文报道了用溶胶−凝胶法制备二氧化钛薄膜时钛酸丁酯水解过程的粘度控制. 研究结果给出了体系粘度随体系的酸碱度、添加乙酰丙酮和硝酸银的变化规律. 通过控制溶液的pH值、乙酰丙酮(AcAc)和硝酸银加入量的方法来控制溶胶的粘度，延缓凝胶化时间，取得了良好的效果.2 实验所用的化学试剂列于表1，以钛酸丁酯[Ti(OC4H9)4]为原料，无水乙醇(C2H5OH)为溶剂，乙酰丙酮(CH3COCH2COCH2)为稳定剂制备二氧化钛薄膜. 首先将钛酸丁酯、无水乙醇、乙酰丙酮按摩尔比为5:20:1的比例混合，在室温下搅伴30 min，再加入H2O，最终使Ti(OC4H9)4与滴加的H2O 的摩尔比为1:2. 采用上海天达仪器厂生产的PHS−3TC(0.01级)型酸度计调节溶液的pH值. 将溶液在室温下搅拌30 min，在40o C温度下，采用上海天平仪器厂生产的NDJ−1型粘度计测定粘度.表1 所用化学试剂Table 1 Chemical reagents used in this workReagent Molecular formula Manufacturer Purity Content Absolute ethanol CH3CH2OH Shanghai No.1 Zhenxing Chemical Co. CP ≥99.7% Titianium tetrabutoxide Ti(OC4H9)4 Shanghai No.3 Reagents Co. CP ≥98.0% Silver nitrate AgNO3 Shanghai Chemical Reagents Co., China Medicine Group AR ≥99.8% Acetylacetone CH3COCH2COCH3Shanghai chemical reagents Co., China Medicine Group CP ≥98.5%收稿日期：2002−02−19，修回日期：2002−−14作者简介：曾贤成(1974−)，男，安徽六安县人，硕士研究生，材料专业；顾四朋、赵启涛和黄瑞安等同学对实验给予了帮助.3 结果与讨论3.1 反应体系酸碱度对粘度的影响为了研究酸碱度对钛酸丁酯的水解-聚合反应的影响，利用浓盐酸和氨水调节溶液的pH 值. 不同反应体系的pH 值分别调节为酸性和碱性. 图1(a)和图1(b)分别为酸性和碱性条件下粘度随时间的变化曲线. 在溶胶−凝胶体系中，加入酸有2个作用：(1) 抑制水解. 溶液中的H +使H 2O H →++OH −反应逆向进行，水解反应变慢；(2) 使Ti −OC 4H 9中的−OC 4H 9基团质子化，从而使胶体粒子带有正电荷，阻止胶团凝聚. 从图1(a)可知，随着溶液酸度的增加，体系的凝胶化时间变长，从pH=7.00时的3.5 h 延长到pH=3.89的500 h. 在酸性条件下，醇盐水解由H 3O +的亲电机理引起，起始阶段水解的速度比缩聚反应快，但是随着时间的推移，醇盐水解活性因其分子上−OR 基团数目减少而下降，缩聚反应在完全水解前已经开始，随着时间的推移，反应速度加快. 反应体系酸度越低，凝胶化时间就越短.11010020406080η (×103－ m P a ·s )t (h)110100020406080η (×102－ m P a ·s )t (h)图1 酸性和碱性条件下粘度随时间的变化Fig.1 Viscosity evolution under acid-catalysis and base-catalysis conditions at 40o C ([AcAc]:[Ti(OC 4H 9)4]=1:5)从图1(b)可以看出，碱催化时溶胶的凝胶化时间比酸催化的短，在将要达到凝胶之前，粘度曲线上升也较陡峭. 这是由于在碱性条件下，水解是由OH −亲核取代引起的. 由于阴离子OH −半径小，它能够直接对钛原子核发动亲核进攻，并使Ti 4+形成五配位的过渡态，OH −离子的进攻使钛原子电子云向另一侧OR −基团偏转，致使钛原子带负电，导致该基团的钛氧键削弱而最终断裂，从而完成水解反应. 醇盐水解反应活性却随分子上−OR 基团数量减少而增大，使所有4个−OR 基团很容易转变为−OH 基团，这就使它的缩聚反应速度大大加快.pH 为7.00和7.08时粘度发生急剧变化的时间在3.8 h 左右，至4 h 时，溶胶发生了凝胶化现象. 而在pH 为8.36时，这一变化时间推迟到175 h 左右. 3.2 乙酰丙酮对粘度的影响乙酰丙酮有酮式和烯醇式2种异构体，其中烯醇式极易与醇盐发生反应形成络合物. 这是由于烯醇式原来连接在与羰基相邻的碳原子上的氢转移到羰基中与氧原子结合，这种重排氢具有很高的活性，极易被其它原子取代，因此乙酰丙酮中的烯醇基比溶胶中的OH −更易与钛酸丁酯发生螯合反应，阻止了钛酸丁酯直接水解，使Ti(OC 4H 9)4中的烷氧基被水中OH −取代的水解反应变慢. Ti(OC 4H 9)4水解后进一步缩聚，缓慢地形成溶胶，并能在较长时间内保持稳定.图2为加入不同量乙酰丙酮时，体系粘度随时间的变化，溶胶体系的pH 值都为6.36. 可以看出随AcAc 加入量增加，凝胶化时间也逐渐增大，到R =[AcAc]:[Ti]=0.5时，凝胶化时间可以达到5期 曾贤成等：Ti(OC 4H 9)4水解过程的粘度控制 4371200 h 以上，AcAc 起到了抑制钛酸丁酯水解的作用. 实验中还发现，适量加入AcAc 可以使Ti(OC 4H 9)4溶胶在很高的pH 值下在半年内保持稳定，这就为制备高质量的TiO 2薄膜创造了优越的条件. 乙酰丙酮与钛酸丁酯的反应是放热反应，形成的络合物会抑制聚合反应，形成的胶体颗粒尺寸较小. 而没有加入AcAc 时，溶胶中胶体颗粒的尺寸相对较大. 在实际制备薄膜时，AcAc 的加入量最好控制在R =0.2左右. 如果加入量太大，粘度增加缓慢，制备薄膜的时间较长. 图2 加入不同量的乙酰丙酮时体系粘度随时间的变化Fig.2 Viscosity evolution in the systems with differentacetylacetone contents at 40o C3.3 硝酸银对粘度的影响图3(a)和3(b)分别是酸催化和碱催化条件下加入AgNO 3反应体系粘度随时间的变化，其中[AgNO 3]:[Ti(OC 4H 9)4]=1:10. 从图3(a)可以看出，在酸催化条件下，没有加入AgNO 3的样品粘度在500 h 左右急剧上升，而加入AgNO 3的样品在750 h 才出现这种情况. 碱催化条件下这种差别更大. 从图3(b)可以看到，在150 h 左右不含AgNO 3的体系粘度即大幅度上升，而加入AgNO 3的体系要到750 h 才会出现类似情况. 对比图3(a)和3(b)可知，碱催化条件下，AgNO 3延缓凝胶化的作用更加显著. 这与HOU 等[8]报道的AgNO 3可以起到稳定剂的作用一致.0200400600800481216η (×103－ m P a ·s )t (h)0200400600800481216η (×103－ m P a ·s )t (h)图3 酸催化和碱催化条件下加入AgNO 3对粘度变化的影响Fig.3 Effect of AgNO 3 on the viscosity evolution in acid-catalyzed and base-catalysed systems at 40o C([AcAc]:[Ti(OC 4H 9)4]=1:5)3.4 二氧化钛薄膜的制备在[AgNO 3]/[Ti(OC 4H 9)4]=1:10，[H 2O]/[Ti]=2:1，pH=2.6左右及不同AcAc 加入量条件下合成溶胶，其粘度达到1500 mPa ⋅s 时成膜. 以K 9玻璃为衬底，采用旋涂法镀膜，旋转速度为2000 r/min ，旋涂时间为30 s. 湿膜在空气中自然干燥0.5 h ，然后放入烘干箱中，200o C 下干燥0.5 h ，最后在625o C 下热处理1 h. 重复上述步骤，进行多次镀膜，即可获得所需厚度的薄膜. 制备的薄膜状况如表2所示. 可以看出，随着AcAc 加入量的增加，TiO 2薄膜质量出现可喜的变化，从开裂比较严重到完全没有开裂，[AcAc]/[Ti]=0.2时成膜质量最好.438 过程工程学报2卷表2 不同AcAc加入量下制备的TiO2薄膜Table 2 The state of TiO2 thin films at different contents of acetylacetone Sample [AcAc]/[Ti] [H2O]/[Ti] [Ag]/[Ti] pH State of TiO2 thin films1 02 0.1 2.61 Seriously cracked2 0.05 2 0.1 2.55 Cracked3 0.10 2 0.1 2.63 Slightly cracked4 0.15 2 0.1 2.60 Almost no crack5 0.20 2 0.1 2.71 No crack4 结论(1) 酸催化条件下，Ti(OC4H9)4−C2H5OH−H2O体系的粘度增长速度随pH值的降低而减缓，体系的凝胶化时间在pH=7时为3.8 h，而在pH=3.89时为500 h. 碱催化条件下，体系凝胶化时间随pH值升高而增长，pH=8.36时，凝胶化时间为175 h以上.(2) 加入乙酰丙酮对体系有很好的稳定作用，在pH=6.36条件下，当[AcAc]/[Ti(OC4H9)4]=3:10时，凝胶化时间为100 h，而当这一比例为5:10时，凝胶化时间则为1200 h，大大提高了溶胶的稳定性.(3) 不论在酸催化还是碱催化条件下，AgNO3的引入都可大大改善溶胶的稳定性，使凝胶化时间推迟至700 h以上. 在碱催化条件下，这种作用更加显著.综上所述，通过调节Ti(OC4H9)4−C2H5OH−H2O体系的pH，添加乙酰丙酮和硝酸银，能够成功地控制体系的粘度变化速度，得到长时间稳定的溶胶，保证制备高质量薄膜.参考文献：[1] Oregan B, Gratzal M. A Low-cost, High-efficiency Solar Cell Based on Dye-sensitized Colloidal TiO2 Films [J]. Nature, 1991,353(24): 7.[2] 邹炳锁，林金谷，汪力，等. 表面包覆TiO2纳米微粒的结构表征、电子态与性质 [J]. 物理学报, 1996, 45(6): 1239−1243.[3] Slunecke J, Kosec M, Holc J, et al. Morphology and Crystallization Behavior of Sol−Gel Derived Titania [J]. J. Am. Ceram.Soc., 1998, 81(5): 1121−1124.[4] Pedraza F, Vazques A. Obtention of TiO2 Rutile at Room Temperature Through Direct Oxidation of TiCl3 [J]. J. Phys. Chem.Solids, 1999, 60(4): 445−448.[5] Slepyn L I. Dynamic Factor in Impact, Phase Transition and Fracture [J]. J. Mech. Phys. Solids, 2000, 48(5): 927−960.[6] Edward J A POPE, Mackenzie J D. Theoretical Modeling of the Structural Evolution of Gels [J]. J. Non-Cryst. Solids, 1988,101: 198−212.[7] Romano S D, Kurlat D H. Rheological Measurements in Titania Gels Synthesized from Reverse Micells [J]. Chem. Phys. Lett.,2000, 323(9): 93−97.[8] HOU L S, LUO W W. Preparation and Properties of Mutlifunctional Coatings for Car-glass by the Sol−Gel Process [A]. ThinSolid Films (Coating on Glass) [C]. 1999. 132−134.Viscosity Control in the Hydrolysis Process of Ti(OC4H9)4 forPreparation of TiO2 Thin FilmsZENG Xian-cheng, HOU Li-song(Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China) Abstract: Hydrolysis characteristics of Ti(OC4H9)4 in the Ti(OC4H9)4−C2H5OH−H2O system were investigated for the preparation of TiO2 thin films via the sol−gel process. Experimental results are given about the effects of the system acidity (or basicity) and the addition of acetylacetone and AgNO3 on the viscosity and gelation time of the system. It was found that the introduction of AgNO3 can greatly improve the stability of the sols and prolong the gelation time besides adjusting pH and adding acetylacetone.Key words: Ti(OC4H9)4; hydrolysis; viscosity; TiO2 thin films。
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High-Efficiency Solar CoatingsBy Lucas Alves and Norman Boling, PhD, Deposition Sciences, Inc.Image courtesy of Deposition Sciences, Inc.Thin films and thin-film technology have played an important role in photovoltaic (PV) power generation for terrestrial and space-qualified applications. Traditionally, the top layer of solar cells has been a thin cover glass, coated with a conventional anti-reflection (AR) coating. This cover glass has served as a radiation barrier, as an optical-coupling element, and as a protective agent against debris, impact and other environmental aggressors. Thin-film coatings are, therefore, critical to the performance and environmental robustness of PV systems.Reprinted fromwww. Solar cell constructionFunctional PV materials are engineered to maximize the conversion of every photon in the solar spectrum into charge carriers. Materials ranging from crystalline silicon (c-Si) to thin-film-based amorphous silicon (a-Si), and from copper indium gallium diselenide (CIGS) to III-V compounds are commonly used. Solar cell designs range from single-junction silicon to inverted multi-junction, and from monolithic to multi-element construction. Systems can be terrestrial (AM 1.5) or space- (AM0) based; the former being divided into one-sun systems and concentrator systems (5-1000 suns), which use lenses and/or mirrors as primary light collectors.As the technology for solar cell construction has evolved, so has the need for thin-film coatings, both simple and complex, used on system elements like lenses, collectors, mirrors and the cell itself. Customizable AR coatings applied to lenses or as top-layer on the cell increase the photon flux reaching the PV medium, while reflecting part of the incident energy that nets only unwanted cell heating. For multi-junction cells, this AR coating can further tailor the spectral response in order to match the currents at the different junctions. Viewed this way, the AR coating can be thought of as a multi-purpose spectral/current regulation coating.High-efficiency solar AR coatingsThe efficiency of a PV solar cell can be quantified by a number of metrics, but one of the most important ones is the external quantum efficiency (EQE) of the device. Whether a PV cell is single-junction or multi-junction, its EQE is a function of the flux of photons reaching the PV medium. It is, therefore, essential to optically match the PV cell to the incident medium in which it operates (air/space). This inevitably requires the addition of one or more interfaces between the solar cell and the incident medium-- in the form of AR coatings.The design of any AR coating can be simply characterized by the irradiance, emittance and absorptance of the sources and media in which the AR will operate. It can also be characterized by the optical properties, index of refraction and extinction coefficient, of the coating materials and substrates used in the optical system. The spectral band over which the coating must operate defines the anti-reflection problem. For PV solar cells implies the solar spectra.“Broadband, highly reflective layers are needed for solar collector and solar concentrator applications.”The inputs to the PV device are the solar spectra, represented by the ASTM G173-03 standard with terrestrial solar spectral irradiance on a specifically oriented surface under one set of atmospheric conditions. These solar spectra are shown in Figure 1. These curves establish the envelope for integrated photon input to the PV medium in the functional 300-2500nm band. Approximately 5% of the solar spectrum falls in the 1900-2500nm range, but this spectral region is normally non-operative since it consists mostly of unwanted heat. Effectively, an optimized broadband solar AR should operate in the 300-1850nm band.Figure 1: ASTM G173-03 solar spectraThe design of a functional BBAR for solar cell systems must take intoconsideration the optical properties of the PV materials and thecomplementary optical thin films. The front surface Fresnel reflectance forany interface can be calculated following the relationship:R = [(n material– n medium)^2 + k material^2]/ [(n material + n medium)^2+k material^2]For the majority of the III-V elements and compounds, the index ofrefraction falls in the n material = 3.0-5.0 range. This results in front-surfacereflectance losses (in AM 1.5) somewhere between R max~25 – 45%.By designing a robust multi-layer BBAR that is matched to the AM 1.5 solar spectrum, we have been able to reduce the front surface reflectance to R avg =< 3% over the 300-1850nm operating band. Figure 2 shows the reflectance of a typical multi-junction solar cell with and without an AR coating applied.Figure 2: Uncoated and coated specular reflectance of LM triple-junction solar celloverlaid with ASTM G173-03 Solar Spectra.Modeling has shown that the application of a multi-layer BBAR can result in a 3-5% gain in the EQE for multi-junction solar cells (under 500x concentration), when compared to the EQE of the same cell using a conventional V-coat AR. Thisperformance gain in cell efficiency makes it possible for commercially available solar cells to breaking into the 40 –50% conversion efficiency range. This is significant in that this type of performance has been observed only with sophisticated solar cell construction in the laboratory environment.Broadband, high reflecting coatingsBroadband, highly reflective layers are needed for solar collector and solar concentrator applications. Typically, the metallic materials used to obtain high reflectivity were either aluminum or silver. Silver is preferred for solarapplications due to its high reflectivity even though this reflectivity falls in theblue and ultraviolet regions of the spectrum. A well-known method to improve the reflectivity of silver is “enhanced silver.”This consists of an optically thick silver layer onto which dielectric layers are deposited to improve the silver’s reflectivity in the blue (around 450nm) from 90% to above 95%. Conventional enhanced silver coatings require a silver layer between 100nm and 600nm in thickness. Deposition Sciences, Inc. (DSI) in Santa Rosa, California has developed a new coating called EcoWhite Silver (patent pending) that uses considerably less silver (generally, 80nm or less) and achieves higher reflectivity in the blue wavelengths than traditional silver coatings.Solar energy collection depends on reflecting large parts of the solar spectrum. The solar spectrum at ground level contains significant energy in the range from 350nm to about 2500nm. Increases in reflectivity in this region can increase the overall efficiency of a solar power system.Solar concentrator systems use multi-junction solar cells, which, as previously mentioned, exploit the solar spectrum from about 350nm to about 1500nm. Due to the available types of semiconductor materials, there is a particular need for very high reflectivity in the short wavelength region of this range, from about 350nm to about 450nm. If insufficient light is available in this wavelength range, the semiconductor junction responsible for converting this light will become reverse-biased, limiting the power output of the other junctions in series.Thus there exists a need for a low-cost reflector coating that has high reflectivity over the range 350nm to 1500nm for concentrated solar PV applications. DSI’s reflector coating with high reflectivity is comprised of a thin layer of aluminum, followed by a thin buffer layer, followed by a thin layer of silver, followed by capping and enhancing layers. As mentioned above, relative to conventional enhanced silver coatings, the new coating uses less silver, has higher blue reflectivity and has high durability.Figure 3: The reduction in blue roll-off using EcoWhite Silver coatings, as compared to standard protected silver coatings, saves material, reduces costs andresults in better performance.SummaryAs attempts are made to reach ever higher collection and conversion efficiencies for commercial CPV systems, thin-film optical coatings play an increasingly important role in the performance of both collection optics and cell-level performance. DSI, in collaboration with the National Renewable Energy Laboratory (NREL), are developing environmentally stable, ultra-durable BBAR coatings for multi-junction metamorphic and lattice-matched solar cells. These coatings have demonstrated as much as a 5% relative gain in the conversion efficiency of solar cell devices.The role of thin-film coatings is expected to continue to grow as the worldwide move from consumable to renewable energy continues to accelerate.About the authorsLucas Alves is Thin Film Design Engineer and Norman Boling, PhD, is Senior Scientist at Deposition Sciences, Inc. (DSI) in Santa Rosa, California.Copyright © 2010 Novus Media Today, LLC. All Rights Reserved.。