全液相两步法金属辅助化学刻蚀制备多晶黑硅太阳能电池

发布时间：2018-05-25 17:24

本文选题：两步法制黑硅 + 金属辅助化学刻蚀　；参考：《苏州大学》2014年硕士论文

【摘要】：近几年，黑硅作为一种具备纳米陷光结构的新型半导体光电材料，由于其在可见——红外波段反射率极低，能够有效的提高电池片的转化效率，因而受到了人们的极大关注。制备黑硅的方法很多，其中金属辅助化学刻蚀法由于所需设备简单、成本低、易于整合到目前太阳能电池生产工序中而备受人们青睐。目前已有许多小组在从事金属辅助化学刻蚀方法的研究，也取得了一定的成果，但大多都采用一步法进行实验。而一步法制黑硅存在两方面的缺点：一方面，反应过程消耗大量的重金属Ag；另一方面，残留过多的金属粒子增加了后续清洗工作的负担。本文研发的全液相两步法不仅可以与产线上现有制绒工艺很好的兼容，而且可以有效的解决一步法制黑硅的两大弊端，这在很大程度上节约了生产成本，也简化了产线上的工艺步骤，所以研究两步法制黑硅具有重要的实践意义。首先，两步法制黑硅(TSM)是指应用控制变量法先将制绒过的硅片先放到硝酸银（催化剂）溶液中反应一定时间，再放入适当体积比的氢氟酸（刻蚀剂）和过氧化氢（氧化剂）混合溶液中反应一段时间，制备出具有纳米陷光的绒面结构，即黑硅结构。本文主要研究了三种溶液浓度以及反应时间下的硅片绒面形貌，选用扫描电子显微镜（SEM）和光学显微镜（OM）对其进行了表征。结果发现：不同的溶液浓度和反应时间会得到纳米线状和孔洞状两种完全不同的结构。其次，本文通过SEM、EDX和粒径分析软件对两步法与一步法制黑硅中Ag颗粒进行了表征，结果发现：两步法消耗非常少的重金属，而且金属粒子分布很均匀，颗粒大小也有一定的规律性。因为两步法反应消耗很少Ag，后续可以很彻底的将残余的金属粒子去除干净，避免了电池片表面金属残余导致的复合。最后，从结构上来看两步法制黑硅相当于在原来微米结构的基础上又生长了一种纳米结构，即形成了一种微纳复合结构，这样就使得硅片的反射率由原来的25%左右降低到5%左右甚至更低。选用标准8度角绒面积分式反射仪（D8反射仪）对黑硅的光学性质进行了表征，并发现确实能够获得极低的反射率。然而，这种具有极低反射率的黑硅却有很深的结构，即很大的比表面积，会大大增加表面载流子复合中心数量，导致电池片的转换效率下降。所以，我们在制完黑硅之后加了一步剥离修正，通过参数的调控可以将纳米陷光结构的深度控制在理想的范围内。本文将两步法制完的多晶黑硅电池在苏州阿特斯阳光电力科技有限公司做了流片分析，流片数据表明该类电池的平均效率为18.05%，高于产线17.52%的平均值。综上所述，我们在实验室和产线上证实了全液相两步法金属辅助化学刻蚀制备黑硅太阳能电池的可行性，，并且与一步法比较体现出了其较大优势。本文的研究内容可以在很大程度上促进我国光伏产业的发展，全液相两步法制黑硅技术存在巨大的实践应用潜力。
[Abstract]:In recent years, as a new type of semiconductor optoelectronic materials with nanometer trapping structure, black silicon has attracted great attention because of its low reflectance in the visible and infrared wavelengths, which can effectively improve the conversion efficiency of the battery. There are many ways to prepare the black silicon, in which the metal assisted chemical etching is the equipment needed. Simple, low cost, easy to integrate into the current production process of solar cells, it is very popular. At present, many groups have been engaged in the research of metal assisted chemical etching methods, and some achievements have been made. But most of them have been experimentation with one step method. There are two shortcomings in the one step process of black silicon. On the one hand, the reaction is over. The process consumes a large amount of heavy metal Ag; on the other hand, excessive residual metal particles increase the burden of subsequent cleaning.
The total liquid phase two step method developed in this paper can not only be compatible with the existing cashmere process in the production line, but also can effectively solve the two disadvantages of the one-step process of the black silicon. This saves the production cost to a great extent, and simplifies the process steps of the production line. Therefore, it is of great practical significance to study the two step method of black silicon.
First, the two step method of black silicon (TSM) is the application of the controlled variable method to first place the flush silicon chip in the silver nitrate (catalyst) solution for a certain time, then reacts in a mixed solution of hydrofluoric acid (etch) and hydrogen peroxide (oxidizer) in a proper volume ratio for a period of time to prepare a nanoscale suede structure, that is, black silicon. Structure. In this paper, three kinds of solution concentration and the surface morphology of silicon wafer under reaction time were mainly studied. Scanning electron microscope (SEM) and optical microscope (OM) were used to characterize it. The results showed that two different structures of nanoscale and hole shape were obtained by different solution concentration and reaction time.
Secondly, the Ag particles in the two step method and one step method of black silicon are characterized by the SEM, EDX and particle size analysis software. The results show that the two step method consumes very little heavy metals, and the distribution of metal particles is very uniform and the size of the particles has a certain regularity. Because the two step method consumes little Ag, and the follow-up can be completely residual. The metal particles are removed cleanly, avoiding the complex of the metal surface of the battery sheet.
Finally, from the structural point of view, the two step black silicon is equivalent to a nano structure on the basis of the original micron structure, that is, a micro nano composite structure is formed, which makes the reflectivity of the silicon wafer lower from about 25% to about 5% or even lower. The standard 8 degree cashmere area fractional reflectometer (D8 reflector) is used for black. The optical properties of silicon have been characterized, and it is found that it does get very low reflectivity. However, this extremely low reflectivity of black silicon has a very deep structure, that is, a large specific surface area, greatly increasing the number of surface carrier complex centers, resulting in a decrease in the conversion efficiency of the battery sheet. The depth of the nanometer trapping structure can be controlled in the ideal range by the step stripping correction. In this paper, the flow sheet analysis of the two step polycrystalline black silicon battery in Suzhou ATS sunshine Electric Technology Co., Ltd. was carried out. The flow sheet data showed that the average efficiency of the battery was 18.05%, higher than the average of the production line 17.52%.
To sum up, we have confirmed the feasibility of preparing black silicon solar cells by full liquid two step metal assisted chemical etching in the laboratory and production line, and compared with one step method. The research content of this paper can greatly promote the development of China's photovoltaic industry and the full liquid phase two step black silicon technology. There is a great potential for practical application.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.4

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