铸造多晶硅的研究进展

近年来,由于低成本和高效率的优势,铸造多晶硅成为最主要的光伏材料之一。现在,其铸造工艺相对成熟：对材料的缺陷和杂质的研究日趋深化,吸杂,钝化及表面结构等技术的应用显著地发问改善了材料的电学和光学性能,实验室水平上,用铸造多晶硅材料制成的太阳电池的转换效率高达18.6%,本文详细阐述了铸造多晶硅材料的研究现状和存在问题,展望今后的发展方向。     

太阳电池用多晶硅及其吸杂研究现状

综述了几类主要的太阳电池用多晶硅及其吸杂研究现状.评述了当前太阳电池领域涉及到的几类多晶硅如铸造多晶硅、冶金法多晶硅、西门子法多晶硅等的优缺点.详细描述了多晶硅的吸杂类型、吸杂过程、吸杂影响因素等.给出了本课题组关于冶金法多晶硅吸杂实验的一些初步研究结果.展望了多晶硅及其吸杂技术的发展.     

铸造多晶硅制备技术的研究进展

近年来,由于低成本、低耗能和少污染的优势,铸造多晶硅成为主要的光伏材料之一,越来越受到人们的广泛关注.系统论述了太阳能级多晶硅制备技术的研究进展,重点介绍了目前铸造多晶硅制备技术,如浇注法(Ingot casting)、定向凝固法及电磁感应加热连续铸造法(EMCP).另外,着重阐述了铸造多晶硅中磷和硼的提纯、多晶硅晶粒组织中晶界和位错的形成与控制以及定向凝固的数值模拟技术,讨论了铸造多晶硅材料的研究现状和存在的问题,展望了今后的发展方向.     

太阳电池发展现状与我国阳光发电规划

本文介绍了我国及其他一些国家太阳电池的发展情况,列举了单晶硅、多晶硅、非晶硅、砷化镓、磷化铟及硒等半导体材料制备的太阳电池的结构、性能指标及产量价格等数据,也报道了我国太阳电池的研制生产情况及近年生产、应用规划。此外还概述了太阳电池的发展远景。     

新能源材料

建“硅谷”,乐山再添年产3000t多晶硅项目;山西建设年产5000t高纯度多晶硅项目;三菱材料多晶硅年产能将提高1000t;尚德签订6．354亿美元多晶硅供应;天津市将建产业化基地研发新型太阳电池……     

铸造多晶硅的制备与研究

当今多晶硅已成为最主要的光伏材料,利用定向凝固工艺生产铸造多晶硅铸锭已成为业界广为采用的方法,但目前利用定向凝固工艺生产出来的多晶硅铸锭仍存在较多的缺陷,例如材料利用率低以及组织不均匀等问题.为了进一步优化铸造工艺,采用自行设计的真空电磁感应熔炼炉及定向凝固炉进行了多晶硅定向凝固实验.重点对比研究了石英坩埚和石英陶瓷坩...     

多晶硅需求结构发生变化

目前，多晶硅市场的需求结构发生了很大变化，正在从以半导体领域为主向半导体和太阳电池两大领域转变。前几年，由于半导体器件需求激增，要求多晶硅产能增加，因此多晶硅厂家增加了生产设备。多晶硅产能的增加投资较大，生产线规模必须在1000-1500t以上。当多晶硅厂家投巨资增加产能后，遭遇到多晶硅需求减少，价格下跌的窘境。此时，太阳电池需求的大幅上涨，给多晶硅厂家带来了生机。     

太阳电池研究进展

晶体硅太阳电池主要朝高效方向发展,薄膜太阳电池特别是多晶硅薄膜太阳电池,由于其廉价,高效,是当前太阳电池研究的热点,也是未来太阳电池发展的方向.分别介绍了第一代、二代太阳电池的发展历程,着重介绍了第三代太阳电池的最新研究进展.     

杂质分布对多晶硅薄膜电性能的影响

报道了多晶硅薄膜的制备方法及光生截流子在多晶硅晶界区域的收集、复合情况，并采用剖面分析方法研究了杂质的分布对多晶硅薄膜太阳电池电性能的影响。     

极富发展前景的多晶硅薄膜太阳电池

太阳能光伏发电具有的许多特征使其对未来能源非常重要,正在形成一门新兴的产业,但达到大规模地面应用需要解决提高光电转换效率和降低成本这两大难题。多晶硅薄膜太阳电池能在廉价衬底上制备,成本远低于晶体硅太阳电池,转换效率可接近晶体硅太阳电池,并且具有光电性能稳定的特点。国内外光伏界都投入了大量的人力物力研究开发多晶硅薄膜太阳电池,取得了可喜的进展。     

多晶硅表面金属催化化学腐蚀法制绒研究现状

在多晶硅太阳能电池的生产过程中,金刚线切割(Diamond wire sawing,DWS)技术具有切割速度快、精度高、原材料损耗少等优点,受到了广泛关注.金刚线切割多晶硅表面形成的损伤层较浅,与传统的酸腐蚀制绒技术无法匹配,金属催化化学腐蚀法应运而生.金属催化化学腐蚀法制绒具有操作简单、结构可控且易形成高深宽比的绒面...     

定向凝固多晶硅的结晶组织及晶体缺陷与杂质研究

多晶硅是目前最主要的光伏材料,其结晶组织、缺陷和杂质含量显著影响太阳能电池的转换效率.通过控制硅锭定向凝固过程获得取向一致、粗大均一的结晶组织和采用各种吸杂及钝化方法降低杂质及缺陷对电学性能的影响是目前提高多晶硅太阳能电池转换效率的重要途径.介绍和评述了国内外包括本研究组对多晶硅的结晶组织及控制、晶体缺陷、杂质水平与分布及其与硅片性能关系的研究进展,并对当前的各种吸杂与钝化方法及其效果进行了总结.     

Relationship between trapping density and open circuit voltage in multicrystalline silicon solar cells

Minority carrier trapping frequently exists in solar grade multicrystalline silicon. At low illumination levels, the effect of trapping centers on open circuit voltage of multicrystalline silicon solar cells is dependent on the trap density and illumination level. In this paper, the relation between trapping density and open circuit voltage of multicrystalline silicon solar cells at different illumination levels is studied by a series of experiments. The experimental evidence suggests that the effect of trapping on open circuit voltage of multicrystalline silicon solar cells is obvious at carrier injection levels equal to and below the trap density, the trapping effect of multicrystalline silicon can be reflected by measuring open circuit voltage at low illumination levels, instead of complicated lifetime measurements, and some multicrystalline silicon solar cells with higher trap densities have higher open-circuit voltages at weak illumination levels. The measurement and analysis of the trapping effect is a relative tool to diagnose the quality of multicrystalline silicon, so a new method is presented to analyze relative quality of multicrystalline silicon by measuring open circuit voltage at weak illumination levels.     

多晶硅太阳电池用SiN薄膜的研究进展

SiN薄膜因为具有良好的减反射性质和钝化作用，已经越来越广泛地应用于多晶硅太阳电池的制造工艺中，介绍了SiN薄膜在硅太阳电池中的性质，制备方法等研究现状，同时提出了存在的问题并展望了今后的发展趋势。     

Properties of plasma enhanced chemical vapor deposited silicon nitride for the application in multicrystalline silicon solar cells

Hydrogenated films of silicon nitride (SiNx:H) were investigated by varying the deposition condition in plasma enhanced chemical vapor deposition (PECVD) reactor and annealing condition in infrared (IR) heated belt furnace to find the optimized condition for the application in multicrystalline silicon solar cells. By varying the gas ratio (ammonia to silane), the silicon nitride films of refractive indices 1.85-2.45 were obtained. Despite the poor deposition rate, silicon wafer with the film deposited at 450 °C showed the best minority carrier lifetime. The film deposited with the gases ratio of 0.57 showed the best peak of carrier lifetime at the annealing temperature of 800 °C. The performance parameters of cells fabricated by varying co-firing peak temperature also showed the best values at 800 °C. The multicrystalline silicon (mc-Si) solar cells fabricated in conventional industrial production line applying the optimized film deposition and annealing conditions on large area substrate (125 mm × 125 mm) was found to have the conversion efficiency of 15%.     

Multicrystalline Silicon for Solar Cells: Process Development by Numerical Simulation

Continuously improving crystallization conditions and solar cell processes have lead to steadily increasing efficiencies of solar cells based on multicrystalline silicon. There is, however, still an efficiency gap between mono‐ and multicrystalline silicon amounting to 1–2 % (absolute) depending on the cell process used. Topographies of the local solar cell performance clearly reveal that the main contribution to this efficiency gap is due to recombination‐active dislocations present in multicrystalline silicon. A further improvement of the efficiencies attainable with multicrystalline solar cells therefore is achievable by a reduction of the dislocation density. Dislocations originate from thermal stress that originates from temperature gradients inside a multicrystalline ingot during crystallization and cooling. In order to reduce this thermal stress and consequently the dislocation density we employ a numerical simulation routine, the so‐called virtual crystallization furnace, for perfect control of the temperature distribution during the entire ingot fabrication process.     

Nanostructure formation and passivation of large-area black silicon for solar cell applications

Nanoscale textured silicon and its passivation are explored by simple low-cost metal-assisted chemical etching and thermal oxidation, and large-area black silicon was fabricated both on single-crystalline Si and multicrystalline Si for solar cell applications. When the Si surface was etched by HF/AgNO(3) solution for 4 or 5 min, nanopores formed in the Si surface, 50-100 nm in diameter and 200-300 nm deep. The nanoscale textured silicon surface turns into an effective medium with a gradually varying refractive index, which leads to the low reflectivity and black appearance of the samples. Mean reflectance was reduced to as low as 2% for crystalline Si and 4% for multicrystalline Si from 300 to 1000 nm, with no antireflective (AR) coating. A black-etched multicrystalline-Si of 156 mm × 156 mm was used to fabricate a primary solar cell with no surface passivation or AR coating. Its conversion efficiency (η) was 11.5%. The cell conversion efficiency was increased greatly by using surface passivation process, which proved very useful in suppressing excess carrier recombination on the nanostructured surface. Finally, a black m-Si cell with efficiency of 15.8% was achieved by using SiO(2) and SiN(X) bilayer passivation structure, indicating that passivation plays a key role in large-scale manufacture of black silicon solar cells.     

Investigation of open-circuit voltage in solar grade silicon solar cells from a metallurgical process route and cell’s defect

The single crystalline silicon solar cells made by solar grade silicon feedstock from a metallurgical process route have an inferior performance than that made by polycrystalline silicon from the chemical route, but the former has a higher open-circuit voltage than the latter under low illumination. In this paper, the open-circuit voltages are calculated under low illumination in solar grade silicon solar cells from a metallurgical process route, and the relationship between open-circuit voltage and trap density are obtained. The result is in excellent agreement with the recent experimental measurements and in harmony with other theoretical calculations. The scientific phenomenon in metallurgical silicon solar cells is explained by modelling and simulation for the first time. It should be emphasized that this phenomenon exists in not only single crystalline silicon solar cells from a metallurgical process route but also multicrystalline silicon solar cells. Finally, the detrimental characteristics of single crystalline silicon solar cells from a metallurgical process route are revealed.