Regulated low cost pre-treatment step for surface texturization of large area industrial single crystalline silicon solar cell

Conventional pre-treatment process for saw damage removal before texturization of monocrystalline silicon wafers is by higher concentration (6-10%) caustic etch at 50-60 degrees C. In this paper a novel low cost approach for this pre-treatment of surface texture by a new composition of hot sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) solution is reported for industrial large area, high efficiency, single crystalline silicon solar cells. The moderate silicon etching rate of hot NaOH-NaOCl solution generates a better control on removal of damaged surface. This new damage etching process also helps in the formation of optimized pyramidal structure on silicon wafer during texturization. This process is highly suitable for thin starting raw wafers with thicknesses in 160-200 mu m range used by most of cell manufacturing industries. Substantial reduction of yield loss due to breakage of wafers is achieved by using this modified process. Optimized recipe of this surface texturization process is ascertained by the Scanning Electron Microscopic (SEM) study of front textured surface on non-metallized and metallized areas. Also reflectivity, cell dark and illuminated voltage-current characteristic measurements validate the superiority of this process to the existing one, which finally leads to low cost, improved quality solar cells for any monocrystalline PV industry. (C) 2010 Elsevier B.V. All rights reserved.