Liquid silicate additive for alkaline texturing of mono-Si wafers to improve process bath lifetime and reduce IPA consumption

Abstract

An improved texturing process is reported for industrial monocrystalline silicon wafers, which uses a small amount of liquid potassium silicate as an additive to the conventional KOH/IPA texturing process. The new silicate additive does not require any other changes to the chemical components and thus can easily be integrated into the standard industrial process. Reflectivity and scanning electron microscope studies confirm that the new process yields smaller pyramidal structures of about 4-6 μm in height, with an improved uniformity across the entire Si surface resulting in a low solar weighted average reflectance (WAR) in the range 11.4-12.2%. Moreover a near three-fold decrease in IPA consumption and a six-fold increase in bath lifetime are achieved by the new texturing process compared to the standard texturing process. For 156 mm×156 mm pseudo-square CZ monocrystalline p-type silicon wafers cell efficiencies of over 18% are achieved with the new texturing process on industrial-grade, screen-printed solar cells fabricated on SERIS' industrial R&D pilot line. This process offers the potential for significant cost reduction in manufacturing of monocrystalline silicon wafer solar cells. © 2013 Elsevier B.V.