Enhanced Photoluminescence from Si Nano-organosols by Functionalization with Alkenes and Their Size Evolution

Silicon nanoparticles ranging from 2 to 16 nm were synthesized by a facile wet chemical route, in which SiO amorphous powder was annealed at 1000 °C, etched in hydrofluoric acid, and surface modified by alkene. After alkyl-termination of the particle surfaces, size selective precipitation technique was applied to separate the nanoparticles into uniform sized fractions. Transmission electron microscopy showed well-dispersed and highly crystalline silicon nanoparticles after the treatment by alkene. Visible room-temperature photoluminescence in the range 800−500 nm was observed from these nanoparticles. The photoluminescence intensity has significantly been enhanced by the surface functionalization. Moreover, the PL peak energy of the size-selected nanoparticles shifted to blue as the size decreased due to quantum confinement effect. The experimental result was also compared with the theoretical predictions and was found to follow the general trend of the model calculations.