Colossal Broad Band Antireflection from Conformally Grown Cu2O on Pyramidally Textured Si and its Photovoltaic Applications

In this paper, we show the efficacy of a conformally grown, self-organized Cu2O overlayer on chemically synthesized, pyramidally textured silicon substrate for a colossal suppression of optical reflection loss. In particular, we demonstrate that p-Cu2O film deposited on a chemically textured n-Si substrate shows an ultra-low average surface reflectance (approximate to 0.25%) over the entire spectral range (300-2400 nm), whereas the same turns out to be approximate to 25% for the film deposited on an as-obtained n-type Si substrate. It is observed that in the former case, Cu2O grows in the form of leaf-like nanostructures, which is attributed to be responsible for such a low reflectance. In addition, under both configurations, the p-Cu2O/n-Si heterostructure shows a non-linear current-voltage characteristics, clearly suggesting the formation of barrier junctions. Further, it is found that a solar cell fabricated with p-Cu2O overlayer grown on a pyramidally textured n-Si substrate shows an eight times higher efficiency compared to the one grown on an as-obtained n-Si substrate. This study will pave the way to design cost-effective and efficient copper oxide-based solar cells.