Investigation of texturization for crystalline silicon solar cells with sodium carbonate solutions

We investigate a new texturization technique for crystalline silicon solar cells with sodium carbonate (Na2CO3) solutions. We show the dependence of the hemispherical surface reflectance on solution temperature, the etching time and the Na2CO3 concentration. Furthermore, we investigate what element in Na2CO3 solution influences the texturing for reducing the texturing time. As a result of experiments, we find it possible to get low reflectance in a shorter texturing time by the addition of NaHCO3. The size of texture becomes smaller by the addition of NaHCO3 but the etching rate does not change. We conclude carbonic ion and/or its compound seems to play an important role as the initiator of pyramidal structure. This texturing method is cost effective because there is no need of expensive IPA, and the surface reflectance is reduced sufficiently in a short time. This method is promising for a large-scale production of crystalline silicon solar cells.