Surface modification of multi-crystalline silicon in photovoltaic cell by laser texturing

Surface of crystalline silicon solar cell plays an important role in its performance. It affects the optical properties which can be determined by surface’ reflectance. To minimize the reflection from the flat surface, thus, improve light trapping, the crystalline silicon wafers must be textured. Through the texturing process, roughness is introduced at the surface, so the incident light has a larger probability of being absorbed into the solar cell. Monocrystalline silicon solar cells can typically be textured using anisotropic alkaline etchants which create randomly distributed pyramids on the surface. However, most of the texturing methods used for monocrystalline silicon wafer are not suitable for multi-crystalline silicon wafer due to grains of random crystallographic orientations. Therefore, isotropic texturing methods are developed. Laser texturing is an isotropic texturing process which utilizes a laser to create pits on the front surface of monocrystalline and multi-crystalline silicon wafers. Then, a special etching procedure should be applied to remove laser-induced damages and other residues. In the following work, the laser processing parameters are going to be justified experimentally. Later, the post texture cleaning process is to be optimized to obtain the required surface morphology. In order to determine the effectiveness of proposed methods, the reflectance and scanning electron microscopy (SEM) images of the textured surface are going to be considered. The aim of the work is finding optimum parameters for laser texturing and also, for post-texture cleaning to improve the efficiency of multi-crystalline silicon solar cell.