Solar energy is the most important basic energy source for various renewable energy sources. Solar photovoltaic cells convert solar radiation energy into electricity. There are a large variety of solar cells. Crystal (monocrystalline and polycrystalline) silicon solar cells have been used on a large scale. China is the world's largest crystalline silicon solar cell manufacturer and supplier. Because of the localization of most raw materials and equipment, silicon solar cells generate electricity. The cost has been declining and is comparable to the cost of coal power generation. It is worth noting that at present, only the silver paste material for preparing the front silver line of silicon solar cells has been monopolized by foreign companies, causing the cost of silver paste to occupy silicon solar cells to increase. Therefore, the in-depth study of the mechanism of silicon solar cells, and the development of new technologies and materials that can improve the efficiency of solar cells and reduce the cost of new silver gate lines are challenging global research and innovation topics.
Recently, Prof. Feng Pan from the School of New Materials of the Shenzhen Graduate School of Peking University proposed to improve the mechanism research of silicon solar cell efficiency and develop new silver wire technology and new materials as important research directions, and as a commitment to innovation in Guangdong Province. One of the core tasks of the team's major projects. In improving the mechanism of silicon solar cell efficiency, the research team is the first to use the Kelvin probe force microscope (KPFM) of the atomic force microscope to detect the surface potential between different interfaces of the crystalline silicon solar cell and discover different interfaces. The relationship between surface potential changes and crystalline silicon solar cell conversion efficiency. This discovery made the team have a more profound understanding of the working principle of crystalline silicon solar cells, and provided an important theoretical basis for improving the performance of crystalline silicon solar cells and improving solar energy conversion efficiency. The relevant research results were recently published in the top journal of international energy materials Nano Energy (Nano Energy 36 (2017) 303-312, impact factor IF=11.6). The work was guided by Prof. Pan Feng, and was completed jointly by Master Yongji Chen of the 2014 grade and Zhang Mingjian, a postdoctoral fellow.
Sample Preparation and Kelvin Probe Force Microscope Working Diagram
Surface potential changes between different interfaces
Glass powder is an important component of silver paste for silicon solar cells. It plays a role in etching the anti-reflection layer silicon nitride. The composition of glass powder directly affects the performance of the battery. The traditional lead-containing glass powder is sintered at high temperature. In the process, first, lead oxide and silicon nitride undergo an etching reaction. As the temperature further increases, the silver in the gate line begins to oxidize and dissolve in the glass melt and further reacts with the silicon nitride, and the reaction reduces a large amount of nanoparticles in the silver. / Silicon interface in the glass layer. The density of silver nanoparticles directly affects the performance of the battery. In order to improve the silver/silicon contact, more dense silver nanoparticles can be obtained in the interface glass layer, and the development of new glass powder is particularly important. Recently, Prof. Feng Pan's research group has made important progress in the development of glass powder, developed a new type of silver-doped glass powder, and formed China's independent intellectual property in this field. Compared with the traditional glass powder, the glass powder has a lower glass transition point, which is favorable for the low-temperature sintering of the crystalline silicon battery. At the same time, the silver-doped glass powder has more dense silver nanoparticles in the silver/silicon interface glass layer. The contact resistance of the battery is greatly reduced, and the efficiency is further improved. The relevant research results were recently published in the internationally renowned journal Chemical Communications (one of the Nature Index's magazines, impact factor IF=6.567) (DOI:10.1039/C7CC02838E) and applied for related invention patents. The work was guided by Prof. Pan Feng and was completed by Yuan Sheng, a master degree graduate of 2014.
Schematic diagram of traditional glass powder and new silver-doped glass powder in the process of sintering crystalline silicon cells
This work was jointly supported by special funds such as Guangdong Innovation Team and Shenzhen Peacock Program.
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