Sulfonate groups assisted texturing for efficient monocrystalline silicon solar cells

Texturing additives have been widely used in the manufacture of monocrystalline silicon solar cells to form a uniform and dense pyramid structure on the silicon surface. However, the texturing mechanism of additives on the silicon surface is still unclear, especially the effect on the anisotropy of different silicon planes when corroded in alkaline solution. Here, we introduced two sulphonates of sodium dodecyl benzene sulfonate (SDBS) and sodium methylene naphthalene sulfonate (NNO) as texturing additive, respectively, which assists the formation of a uniform and dense pyramid structure on the silicon surface. In the light of theoretical calculations, it is found that sulfonate group is easier to adsorb on the (100) and (111) crystal planes of monocrystalline silicon than hydroxide group, so that sulfonate groups can protect the formed pyramid structure and reduce the etching rate. In addition, we also study the texture effect of NNO, and find that when the concentration of NNO is 20 ppm, the surface passivation effect of silicon wafer is the best, and the average efficiency of the corresponding monocrystalline silicon Selective Emitter Passivated Emitter and Rear Contact (SE-PERC) solar cells reaches 23.17%. This texture system containing NNO, whose core is sulfonate group, has an excellent application prospect in the manufacture of monocrystalline silicon SE-PERC solar cells.