Facile and stable fabrication of wafer-scale, ultra-black -silicon with 3D nano/micro hybrid structures for solar cells.

Three-dimensional (3D) silicon (Si) nanostructures have attracted much attention in solar cells due to their excellent broadband and omnidirectional light-harvesting properties. However, the development of 3D Si nanostructures is still plagued by the trade-off between structural complexity and fabrication difficulty. Herein, we proposed a facile and stable approach toward the fabrication of wafer-scale, ultra-black crystalline silicon (c-Si) with nano/micro hybrid structures. The distinguishing advantage of this approach is that it allows the formation of 3D Si nano/micro hybrid structures in a single-round process, avoiding the need for multiple iterations of lithography, coating, and etching required in conventional processes. The nano/micro hybrid structure arrays we fabricated show a low reflectance of <1% in the 600-1000 nm wavelength range and absorb 98.82% of incident light in the visible and near-infrared regions from 400 to 1100 nm under AM 1.5 G illumination. Solar cells made from nano/micro hybrid 3D structure arrays have an efficiency improvement of about 11.4% compared to those made from mono-micropillar arrays, and they have potential applications in high-performance photovoltaic devices.