Up to 20% efficient solar cells on monocrystalline silicon wafers by using a KOH - High Boiling Alcohol (HBA) texturing solution

Abstract

We have textured (100) p-type Czochralski (Cz) monocrystalline Silicon (Si) wafers by using an aqueous solution of potassium hydroxide (KOH) and a High Boiling Alcohol (HBA). Cz-Si wafers textured with the KOH-HBA solution were processed into solar cells via the standard industrial screen printing method and an advanced industrial process (selective emitter process). Also, high quality float zone (FZ) Si material was textured and processed into solar cells by using a lab-type cell process. Industrially processed cells achieve efficiencies of 17.6% and 18.2%, respectively. Lab-type processed cells (2x2 cm2) achieve an efficiency of up to 20%. In addition, for the standard KOH-Isopropyl alcohol (IPA) etching solution a new etching bath setup has been developed. The new bath setup allows the recuperation of IPA during the texturisation process, as well as vacuum processing steps during the texturisation, which considerably reduces etching time.