Novel ZnO nanowires/silicon hierarchical structures for superhydrophobic, low reflection, and high efficiency solar cells

For current solar cell technique, low conversion efficiency is the main limiting factor. A large portion of energy loss during solar cell operation could be attributed to optical loss, namely reflection loss of the incoming light. To reduce the reflection loss, surface texturing and antireflection coatings are most commonly used strategies. We report a novel hierarchical structure of integrating ZnO nanowire arrays on Si micropyramids as an effective anti-reflection layer for improving the energy conversion efficiency. This structure displays a broadband reflection suppression in the 300-1200 nm range, with an average weighted reflectance of 3.2%, much lower than the previously reported 6.6% reflectance of tapered ZnO nanostructures on planar surfaces. Sunrays 1.3 simulation was employed for optimizing and a better understanding of the effect of hierarchical structure in reflectance suppression. In addition, the surface modification enables a self cleaning property that will prevent the blocking of light by dust particles on solar panels.