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

Abstract

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.

Size-Selective Separation Techniques for Nanoparticles in Liquid

“…While many separation methods for NPs are proposed, from traditional separation science (filtration, chromatography, extraction) to nanoscale specific phenomena (field-flow fractionation, size selective precipitation), the continuous operation methods or techniques for the industrial scale are still sought after and are the main challenge for future research on size-selective separation of NPs. (Vossmeyer T. et al, 1994) ZnS cysteine water ethanol (Bae W. and Mehra R.K., 1998) CdTe 1-TG, TGA, 2-ME water 2-propanol (Gaponik N. et al, 2002) ZnSe x Te 1-x TGA water 2-propanol (Li C. et al, 2008) ZnS:Mn 1-TG water 2-propanol (Komada S. et al, 2012, Segets D. et al, 2013 Si octadecene chloroform methanol (Li X. et al, 2004) Si 1-octene toluene methanol (Liu S.M. et al, 2006) Si allylbenzene toluene methanol (Mastronardi M.L.…”

Colloidal silicon quantum dots: synthesis and luminescence tuning from the near-UV to the near-IR range

“…It was confirmed by HRTEM that the product etched with HF was silicon QDs of 4.2 nm diameter, and the polydispersity was estimated to be around 12%. The formation of a diamond cubic lattice was confirmed by XRD [98]. The Veinot group did extensive studies on this process using different precursors.…”

Size effect on electronic transport in nC–Si/SiO core/shell quantum dots

“…Following solid phase annealing of silicon suboxide materials, silicon nanocrystals embedded in oxide matrices have been prepared [15,16]. Si nanoparticles wrapped in silicon oxide layer obtained from solution process showed stable PL properties [17,18].…”