Black silicon based on simple fabrication of mesoporous silicon nanowires for solar energy harvesting

We report large-scale fabrication of black silicon based on mesoporous silicon nanowires (SiNWs) with reflectance <;0.1% in the solar irradiance peak (wavelength range 400 to 800 nm). The black silicon reflects <;2% at different incident angles up to ±60°. The black silicon consists of mesporous SiNWs of diameters in the range 130-750 nm, matching the wavelength of the incident light for improved light trapping inside the nanostructure. SiNWs were synthesized through catalytic wet chemical etching. This study shows that black silicon surfaces based on mesoporous SiNWs can be used as an efficient broadband absorber for solar energy harvesting without any need for antireflective coating.