Novel and efficient texturing approach for large-scale industrial production line of large-area monocrystalline silicon solar cell

Abstract

Texturing monocrystalline silicon (c-Si) for solar cell fabrication is still a key issue due to consumption of a large amount of costly isopropyl alcohol (IPA) in conventional NaOH/KOH solution. Controlling IPA amount in NaOH/KOH-texturing bath for longer life of the solution in industrial batch production is a difficult task. This article reports the use of a chemical bath with a composition of NaOH–NaOCl (sodium hydroxide–sodium hypochlorite) for texturing monocrystalline silicon surface for solar cell fabrication. We report such a novel concept of texturing of the c-Si surface without using IPA and discarding the saw damage removal step. The optimized etching condition with NaOH–NaOCl-containing solution does not have any negative effect on monocrystalline silicon solar cell efficiency. Easy control of the process due to the self-controlled reaction is one of the major advantages and there is no need of sophisticated temperature-controlling system during texturing in the industrial batch process. Moreover, FTIR analysis shows the formation of Si–Cl bond during texturing, which improves the quality of diffused junction due to the gettering effect of Cl. Solar cell of conversion efficiency 14.5–15.8 % on CZ–Si substrate of area 125 mm × 125 mm was successfully fabricated using a novel texturing approach in industrial production line with yield >85 %.