Novel Synthesis and Effective Surface Protection of Air-Stable Luminescent Silicon Nanoparticles

Air-stable luminescent silicon nanoparticles with effective surface protection are reported as a quantum dot material with high emission quantum yield. The silicon nanoparticles are prepared by a novel reaction of SiO2 with phenol resins and characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle size of the silicon nanoparticles is controlled by an acid-etching process with hydrofluoric and nitric acids in methanol. The particle size estimated from emission spectra was less than 5 nm. The surfaces of the silicon nanoparticles are protected using a photoassisted reaction with styrene molecules after the acid-etching process. The surface-protected silicon nanoparticles exhibit luminescence at around 650 nm, and their emission quantum yield is estimated to be 55%.