Near white light emission of silicon nanocrystals

Silicon nanoparticles in the range from 2 nm to 5 nm was prepared from Zintl salt, soldium silicide (NaSi) by sonochemical method. This synthesis permits the reaction completed as fast as in a few hours and the easy alkylmodification of nanocrystals surface at room temperature and ambient pressure. The average size of nanoparticles measured by the dynamic light scattering analysis was 2.7 nm. The high-resolution transmission electron micrograph confirmed the material identity of nanoparticles as crystalline silicon. Fr-IR spectra are consistent with the surface states of nanocrystals that is chlorine- or butyl-capped. The emission peak center moved to longer wavelength (up to 430 nm) with the reaction time, under a 325 nm excitation. The luminescence of silicon colloids looks bright bluish-white under excitation using a commercial low-intensity LTV lamp.