Light-trapping improvement of limited-quality silicon wafers for silicon heterojunction solar cell applications

Laser-based surface texturing treatments have been investigated as a promising option for innovative low-cost concepts to improve the light absorption of silicon heterojunction solar cells manufactured from unconventional silicon wafers. A great advantage of using a laser as a processing tool is its high precision, which lead to selected and well-controlled morphologies. This is a particularly interesting feature for multicrystalline silicon wafers, where the large number of grain boundaries makes it difficult to obtain high light-trapping morphologies by other methods. The investigations described in this work include testing different patterns on the wafer surface in order to define the best morphology to improve the light absorption. A significant decrease in reflectance (R<9%) has been achieved by direct-laser texturization and has been compared with acid-chemical etching with average reflectance above 20%. This result suggests the enormous potential of direct laser texturization for this type of wafers, without chemical residues and its easy incorporation to the manufacturing of low-cost silicon heterojunction solar cells.