Exploring low temperature-sputtered indium tin oxide (ITO) as an anti-reflection layer for silicon solar cells

Abstract

This paper tackles challenges in silicon (Si) solar cells, specifically the use of hazardous Phosphorus Oxychloride (POCl3) for emitter formation and silane/ammonia for the Anti-Reflective Coating (ARC) layer, accompanied by high-temperature metallization. The study proposes an eco-friendly ARC layer process, replacing toxic materials. Indium Tin Oxide (ITO) with a refractive index of ~2.0 is suggested as a non-toxic substitute for SiNx in the ARC layer. ITO enables fine-tuning of optical parameters and, with its electrical properties, supports low-resistivity contacts through efficient, low-temperature metallization processes. ITO-passivated solar cells with Ag polymer paste as a front contact exhibit promising characteristics: a commendable photocurrent density (Jsc) of 20 mA/cm2 at 850°C, low series resistance (Rs) of 1.9 Ω, and high shunt resistance (Rshunt) of 28.9 Ω, as demonstrated by illuminated I-V measurements. Implementing ITO as the ARC on a less toxic emitter junction enhances Si solar cells current density gain, minimizing current leakage during high-temperature processing. In conclusion, adopting less toxic materials and employing low-temperature processing in passive silicon solar cell fabrication present an attractive alternative for cost reduction and contribute to environmentally sustainable practices in green manufacturing.