A kind of texturing method for diamond wire cutting polycrystalline silicon wafer solar cells

Abstract

A method for texturing a diamond-cut polycrystalline silicon solar cell comprises steps of: coating the surface of a diamond-cut polycrystalline silicon wafer with a photoresist to form a photoresistmask layer; forming a mask pattern by exposure and development; treating the surface of the photoresist mask layer in order that the surface contact angle of the photoresist mask layer is reduced under 15 degrees at the temperature of 25 degrees centigrade; placing the diamond-cut polycrystalline silicon wafer on a roller in such a way that the surface where the photoresist mask layer is formed faces downward, placing the roller in an acidic etching solution, etching the silicon wafer on one side, and placing the etched diamond-cut polycrystalline silicon wafer into a high temperature sintering furnace to remove the remaining photoresist on the surface, and subjecting the sintered diamond-cut polycrystalline silicon wafer to acid washing, caustic washing and water washing to obtain a texture structure. The method improves a current wet texturing process which requires the silicon wafer to be integrally immersed in the acid solution, particularly improves the disadvantage that the backside of the silicon wafer must be protected during the mask wet etching, greatly saves the cost and improves production efficiency.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a texturing method for polycrystalline silicon chip solar cells cut by diamond wires. Background technique [0002] The process of texturing the surface of solar cells to form an effective anti-reflection effect is called texturing, which is one of the important means to increase the efficiency of solar cells. Due to the disordered crystal orientation of polycrystalline silicon, it is impossible to obtain a uniform pyramid texture-like structure through anisotropic etching like monocrystalline silicon. The structure of polycrystalline silicon texture is messy, and the shape, size and depth are irregular, so the reflectivity is high (above 22%), resulting in a gap of at least 0.5% in cell efficiency compared with monocrystalline silicon. Even though low light reflectivity is achieved, very many surface defects tend to be generated, leading to increased carrier recombination, ...

AI Technical Summary

Problems solved by technology

At this time, the etching speed and reaction degree of the backside of the silicon wafer not covered by the mask are much greater than that of the surface of the silicon wafer covered by the mask. Form a textured structure with a depth of several microns, which will easily lead to the deterioration of the mechanical strength of the silicon wafer, especially for the increasingly thinner polycrystalline silicon wafers, so it is necessary to use a protective film on the back of the silicon wafer. to prevent the etching reaction from proceeding

The process of back protection not only wastes the back protection material, but also increases the cost, and the removal of the back protection material after etching also increases the cost and reduces the production efficiency.

However, in the wet mask etching, the single-side etching is achieved without dipping, for example, only the surface of the silicon wafer covered by the mask is exposed to the etching solution. It seems very simple, but in fact it is completely impossible to form a stable Etching reaction, so there are basically no reports of true single-sided etching in masked wet etching

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