In this work, alkaline-based anisotropic etchants, tetramethylammonium hydroxide (TMAH) and potassium hydroxide (KOH)/isopropyl alcohol (IPA) solutions, have been used for the surface texturing of the single-crystalline silicon wafers used for solar cells. The pyramid morphology produced by the surface texturing can reduce the surface reflection of the incident light and increase the light absorption so that the efficiency of the solar cells can be increased. The experimental data shows that the optimized surface texturing has been obtained with 5 wt. % TMAH anisotropic etching at 80 °C. The surface reflectance of the polished front surface can be reduced to 17 % and the surface reflectance of the unpolished backside surface can be reduced to 3 %, respectively. This result shows that the anisotropic etching can effectively reduce the surface reflectance. While for the surface texturing with KOH/IPA mixture, the front surface reflectance can only be reduced to 35 % and the backside surface reflectance can only be reduced to 5 %, respectively. Besides, debris of Si nano-crystals exists around the pyramid base area when texturing with the KOH/IPA mixture.
21%-efficient PERL Solar Cells with Plated Front Contacts on Industrial 156mm p-type Crystalline Silicon Wafers
