Solar cells and materials research Pyeongchang original | 2010-1-26 17:27 | vote | Read: 25 This recommendation has been edited Views: 25 Keywords: solar cells and materials research Solar energy is inexhaustible renewable human energy. Is also clean energy, not produce any environmental pollution. Effective use of them in solar; large photovoltaic solar energy use in recent years is the fastest growing, most dynamic area of research, is one of the most watched items. To this end, people have developed a solar cell. Solar cells are mainly based on semiconductor materials, its working principle is the use of photovoltaic materials absorb light energy of conversion occurred after the photoelectric response, according to the different materials, solar cells can be divided into: 1, silicon solar cells; 2 to inorganic salts such as III-V compounds GaAs, CdS, copper indium selenium compounds such as multi-material cell; 3, Functional Polymer Materials of large solar energy battery; 4, nanocrystalline solar cells. Regardless of what material to produce batteries, solar cell material on the general requirements are: ①, the band gap semiconductor materials can not be too wide; ②, have a higher photoelectric conversion efficiency of: ③, the material itself does not cause pollution to the environment; ④, material suitable for mass production and materials performance and stability. Based on the above aspects to consider, is the ideal silicon solar cell material, which is silicon-based solar cells to the main reason. But with the continuous development of new materials and related technology to other village-based solar cell materials have shown more and more attractive prospects. This paper briefly reviews the types of solar cells and its research status, and discussed the development trend of solar cells. 1, silicon solar cells 1.1 monocrystalline silicon solar cells Silicon Series Solar Cells, Silicon Solar energy conversion efficiency of the battery top, the most mature technology. High-performance silicon solar cell is built on high-quality silicon and related materials into a heat treatment process based on the processing. Electricity to process silicon now has nearly mature, in the battery production, is generally used texturing, emitter passivation, area doping technology, the development of the battery mainly flat groove buried monocrystalline silicon cells and silicon gate electrode battery. Improve the conversion efficiency depends mainly on the silicon surface micro-structure of treatment and doping process area. In this regard, the German Institute for Solar Energy Systems Fort 夫朗霍费费莱 maintains the world&#39;s advanced level. The Institute will use lithography photography texture of the surface of the battery, made pyramid. And the surface to a 13nm, thick oxide passivation layer and the combination of two anti-reflection coating, plating process by improving the gate to increase the ratio of the width and height: the above conversion efficiency of the battery obtained more than 23 %, is the largest value of up to 23.3%. Kyocera Corporation prepared a large area (225cm2) single-crystal solar cell power conversion efficiency of 19.44%, China Beijing Solar Energy Research Institute is also active and efficient crystalline silicon solar cell research and development, the development of highly efficient silicon solar cell surface (2cm × 2cm ) conversion efficiency of 19.79%, groove buried gate electrode of crystalline silicon cells (5cm × 5cm) conversion efficiency of 8.6%. Monocrystalline silicon solar cell conversion efficiency is undoubtedly the highest in the large-scale applications and industrial production is still dominant, but due to Dan Jinggui material prices and the corresponding complicated process affects the battery, causing the high silicon cost price home no less, to a significant reduction in the cost is very difficult. To save high-quality materials, look for silicon solar cell replacement product, and now developed a thin film solar power Pool, in which polycrystalline silicon thin film solar cells and amorphous silicon thin film solar cells are typical examples. 1.2 polycrystalline silicon thin film solar cells Crystal silicon solar cells are usually in the thickness of 350 ~ 450μm made of high-quality silicon, such silicon Czochralski or cast from the cutting of silicon ingots made. Therefore, the actual consumption of silicon materials for more. To save material, people from the mid-70s began low-cost polycrystalline silicon thin film deposited on the substrate, but the growth of silicon film grain size, not made of valuable solar cells. In order to obtain large grain of film, it has not stopped research and made a lot of ways. Preparation of polycrystalline silicon thin film over the current use of chemical vapor deposition, including low pressure chemical vapor deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD) process. In addition, the liquid phase epitaxy method (LPPE) and sputtering deposition can also be used to prepare polycrystalline silicon thin film batteries. Chemical vapor deposition mainly SiH2Cl2, SiHCl3, Sicl4 or SiH4, as the reactive gas atmosphere in a protective reaction of silicon atoms and deposition in the heated substrate, the substrate material generally used in the Si, SiO2, Si3N4, etc.. But the study found that non-silicon substrates is difficult to form larger grains, and easy to form a gap between grains. Way to solve this problem is to first substrate using LPCVD Shen Chi in a thin layer of amorphous silicon layer, then this layer of amorphous silicon layer annealing, have larger grains, and then seed at this level thick polysilicon thin film deposition, therefore, re-crystallization is undoubtedly a very important aspect of the technology currently used mainly in the solid phase crystallization and zone melting recrystallization. In addition to polycrystalline silicon thin film cells using recrystallization process, the other with almost all the technical preparation of monocrystalline silicon solar cells, solar cells obtained by this conversion efficiency has improved significantly. Solar Energy Research Institute in Germany by German Freiburg District Museum recrystallization in FZ Si substrates obtained polysilicon cell efficiency is 19%, the Japanese Mitsubishi company prepared to use the battery efficiency of 16.42%. Liquid phase epitaxy (LPE) method works by melting the silicon in the matrix, the lower temperature precipitation of silicon film. U.S. Astropower company prepared by LPE cell efficiency of 12.2%. The development of China&#39;s Optoelectronic Technology Center Chen Zheliang by liquid phase epitaxy in the growth of metallurgical grade silicon crystal on silicon, and designed a similar crystalline silicon thin film solar cells a new type of solar cell, called &quot;silicon particles&quot; solar cells But the performance reports have yet to see. Polysilicon thin film silicon cells used as less than silicon, and inefficient recession, and may low-cost substrate materials in the preparation, the cost is far lower than the silicon solar cell, while more efficient than amorphous silicon thin film battery, therefore, polycrystalline silicon thin film solar cells will soon dominate the local market. 1.3 amorphous silicon thin film solar cells Development of solar cells are two key question is: to improve efficiency and reduce costs. As the amorphous silicon thin film solar cells and low cost, easy mass production, the general attention by people and the rapid development, Qishizaozai the early 70&#39;s, Carlson Deng has already begun on the development of the Fei Jinggui battery Gongzuo, Jinji In its development work has been rapid development, many of the world had Companies in the production of the kinds of batteries. Although amorphous silicon material as a solar battery is a good material, but because of its optical band gap of 1.7eV, makes the material itself on the solar radiation spectrum is not sensitive to long wavelength region, such an action would limit the amorphous silicon solar cells conversion efficiency. In addition, the optical efficiency will continue as the illumination time and decay, the so-called S 1 W of light induced degradation effect, making stable cell performance. Solve these problems is the preparation of this track tandem solar cells, tandem solar cells prepared by the p, i, n single-junction solar cell layer re-deposited one or more sub-battery system obtained Pin. Improve the conversion efficiency of tandem solar cells to address the stability of single-junction solar cell is not the key question: ①, which the band gap of the material in different branches units together to improve the spectral response range; ②, the top cell i layer thin, light produced little change in the electric field strength to ensure the i layer of light-induced carriers out; ③, produced by the end of the battery carrier is about half the single-cell, light induced degradation effect decreased; ④, tandem solar cells is the son of batteries together in series. Preparation of amorphous silicon thin film solar cells there are many ways, including reactive sputtering, PECVD method, LPCVD law, the reaction feed gas for the H2 diluted SiH4, mainly glass and stainless steel substrate film made of amorphous silicon film through the various cell processes, respectively obtained by single-junction tandem solar cells and batteries. Amorphous silicon solar cells currently achieve two major advances: first, the three tandem structure amorphous silicon solar cell conversion efficiency of 13%, setting a new record; the second and third tandem solar cell annual production capacity of 5MW. United Solar Corporation (VSSC) obtained the highest single-junction solar cell conversion efficiency of 9.3%, three three-band gap tandem solar cell conversion efficiency of 13% maximum. The maximum conversion efficiency is in the small area (0.25cm2) battery made. Some literature reported that single-junction amorphous silicon solar cell conversion efficiency of more than 12.5%, Japan&#39;s Academia Sinica, using a series of new measures obtained in the amorphous silicon cell efficiency of 13.2%. Domestic battery, especially on the amorphous silicon thin film tandem solar cells have not been studied, Nankai University, Geng Xinhua and other industrial materials used to prepare the aluminum back electrode area 20X20cm2, conversion efficiency was 8.28% of the a-Si / a-Si tandem solar cells. Amorphous silicon solar cells with high conversion efficiency and low cost and light weight, has great potential. But the stability is not high because of its direct impact on its practical application. If we can solve the stability problems and further improve the conversion rate of the problem, then the sun can be amorphous silicon solar battery is undoubtedly one of the major development of products.
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