Preparation And Electrical Properties Of Large Size Black Silicon Texture Of Multicrystalline Silicon Solar Cell

With the development of the silicon-based solar photovoltaic industry,diamond wire-sawn silicon technology has attracted attention because of its economical and environmentally friendly,high cutting efficiency,and the low fragmentation rate of the cut silicon wafer in solar cell manufacturing.However,due to the special amorphous structure of the diamond wire-sawn multi crystal line silicon surface,it is difficult to produce a desired texture on the surface of the silicon wafer,thereby limiting its use as a crystalline silicon solar cell.The Metal Assisted Chemical Etching(MACE)method is not limited by the surface structure of the silicon substrate, and can be used to prepare a well light-trapping texture on both the wire line cut silicon and the diamond wire-sawn silicon(The industry is called black silicon),so MACE is expected to become an important means of texturing for diamond wire-sawn multicrystalline silicon wafers. However,the black silicon prepared by the conventional MACE method has a too fine nanopore structure,and the pitch of the etching pits and the sidewalls between them are too small,and the "heavily doped" defects are easily generated in the phosphorus diffusion process.In order to reduce the "heavy doping",it is necessary to carry out a modification treatment with mixed acid solution.After the etching treatment,the sidewall of the nanopore with fine trapping on the suede surface will be etched,which will make the light-trapping effect of the texture worse, affecting the absorption of light by the silicon wafer and affecting the photoelectric conversion efficiency of the solar cell.In this paper,electrochemical etching and mask-MACE were used to prepare black silicon texture with large etch pit spacing and thick sidewalls to improve thelight trapping effect of the texture.In this paper,the double-groove method is used to electrochemically etch the diamond line cutting multicrystalline silicon wafer in potassium hydroxide(KOH)solution.First,chemical pretreatment with KOH solution can generate the activation point or induced point of subsequent electrochemical etching,the uniformity of the electrochemical etching is improved;then the pre-treated test piece was subjected to KOH electrochemical etching,and the influence of the concentration of the etching solution,the temperature,the etching voltage and other factors on the texture of the multicrystalline silicon is analyzed.The prepared multicrystalline silicon texture is ideal,the etching pit is evenly distributed,and the light trapping effect is also good.The final minimum reflectance of the texture obtained is around 18%.In this paper,the nano-silicon powder ethanol dispersion/silicon hollow sphere acid sol dispersion was used as the mask material,and the multicrystaline silicon texture structure was prepared by MACE.By studying the properties and structure of the mask and the influence of different mask concentrations on the morphology of the mask,the rule of mask-texturing was preliminarily found,and the multicrystalline silicon texture prepared MACE was ideal,although the overall trapping effect is general,but locally has a locally well texture structure and distribution of corrosion pits,and the minimum reflectance of the local region is about 16.2%.In this paper,the phenolic resin-ethanol-water system was used as the mask material to study the properties of the mask,and the multicrystalline silicon texture structure was prepared by MACE.By studying the effects of different water/resin ratios,pulling speeds and mask drying speeds on the morphology of the mask,a speckle matrix mask with a size and spacing of about 1 μm and 2 μm was prepared and combined with MACE.A surface of the silicon wafer with a minimum reflectance of 14.2%was prepared.After fabricated the solar cell,its photoelectric conversion efficiency is higher than that of ordinary black silicon cells with the same reflectivity by nearly 0.13 percentage points.