Photoluminescent silicon nanocrystals stabilized by ionic liquid

Silicon nanocrystals stabilized by an ionic liquid, dimethylimidazolium iodide, were synthesized by chemical reduction of SiBr4 with metallic Na in an organic solvent, diglyme. The nanoparticles were crystalline with a diamond cubic lattice and average size of 3.5 nm. Solid state 13C- and 29Si-NMR CP MAS spectra indicate the formation of imidazolium carbene, which ligates the Si atoms at the surface of the nanoparticles. The synthesized Si nanoparticles exhibit photoluminescence with an emission maximum in the red spectral range when excited at 320 nm. The origin of this luminescence is suggested to be mainly related to quantum confinement.