Improving optical and electrical properties of micropillar and black-Si solar cells by combining them into a superstructure

While nanostructured surface such as black silicon is an efficiency way to reduce the surface reflection, the high surface area impedes the application of photoelectronic conversion. On the other hand, micropillar is a promising alternative to efficiently collect carriers, but the pillar diameter is usually larger than the wavelength of light that makes surface reflection high. In this study we report an approach to reduce the surface reflection of micropillars by combining micropillar and nanostructure to create a superstructure that concurrently improves the electrical and optical properties. We found that the averaged reflection was reduced from 16.73% to 9.63%, and the efficiency was increased from 9.26% to 9.62% via only 2% modification in micropillar height.