Shulou(Shulou.com)11/24 Report--

Thanks to the CTOnews.com netizen Mr. Air, Xiao Zhanche's clue delivery! CTOnews.com, May 25, solar energy is a clean and renewable energy, and monocrystalline silicon solar cell is one of the most efficient and widely used solar energy conversion technologies. However, monocrystalline silicon solar cells also have some shortcomings, such as large weight, easy to break, not suitable for bending and so on, which limits its application in wearable electronics, photovoltaic building integration, aerospace and other fields.

CTOnews.com learned from official account of Shanghai Institute of Microsystems of the Chinese Academy of Sciences that the team of the institute observed through high-speed cameras that the fracture of monocrystalline silicon solar cells under bending stress always begins with a "V" groove on the edge of the wafer, which is defined as the "mechanical short plate" of the wafer. According to this phenomenon, the research team creatively developed the edge smooth treatment technology, which treats the sharp V-shaped grooves on the surface and side of the silicon wafer into smooth U-shaped grooves to change the structural symmetry on the mesoscopic scale. combined with finite element analysis, molecular dynamics simulation under dynamic stress load and residual stress analysis of spherical aberration transmission electron microscope It is found that the "brittle" fracture behavior of monocrystalline silicon changes into the fracture behavior of "elastic-plastic" secondary shear band. At the same time, because the smooth treatment is limited to the edge area of the silicon wafer, it does not affect the light absorption capacity of the surface and back of the silicon wafer, thus keeping the photoelectric conversion efficiency of the solar cell unchanged.

Figure 1. A, flexible solar cell silicon wafer bending radius less than 5 mm; b, flexible solar cell bending angle more than 360 degrees.

Figure 2. Flexible monocrystalline silicon solar cell modules have been successfully used in near space vehicles, photovoltaic building integration, vehicle photovoltaic and other fields. The structural design scheme can significantly improve the "flexibility" of silicon wafers, and monocrystalline silicon solar cells with a thickness of 60 microns can be folded like A4 paper with a minimum bending radius of less than 5 mm (figure 1A). The bending angle is more than 360 degrees (figure 1b).

The feasibility of mass production of this flexible monocrystalline silicon solar cell has been verified in the mass production line, and has been applied in the fields of near space aircraft, building photovoltaic integration and vehicle photovoltaic. This result was published in the top international academic journal Nature on May 24, 2023, and was selected as the cover of the current issue.

The author of this paper, researcher Di Zengfeng and Liu Zhengxin, said that this work provides a feasible technical route for the development of lightweight and flexible monocrystalline silicon solar cells. it will have broad application prospects in space applications, green buildings, portable power sources and so on in the future.

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