Multi-layer TCO based anti-reflective coatings for silicon solar cells

D.N. Wright, A. Ulyashin, A. Bentzen, E.S. Marstein, A. Holt, Proceedings of the 21th European Photovoltaic Solar Energy Conference, Dresden, Germany, (2006) 1211-1214

Transparent conducting oxides, such as Indium-Tin Oxide (ITO) layers, are widely used as combined anti-reflection coatings (ARC) and transparent electrodes on silicon (Si) based solar cells. However, the usefulness of an ITO ARC is limited by a lack of surface passivation combined with a non-negligible absorption. A promising prospect is the use of multi-layer approaches, where films of different materials, some of which yield passivation, are combined. In this paper, the results of optical simulations of 4 different possible designs incorporating ITO, silicon nitride (SiNx:H) and silicon oxide (SiO) are presented. The best design improved the transmittance into the Si solar cell by 10% absolute compared to an ITO ARC. It was also found that these designs were very insensitive to variations in the SiN:H thickness, SiO thickness and SiN:H refractive index.