title: Preparation of monodisperse silicon nanocrystals using density gradient ultracentrifugation.
abstract: We report the preparation of monodisperse silicon nanocrystals (ncSi) by size-separation of polydisperse alkyl-capped ncSi using organic density gradient ultracentrifugation. The ncSi were synthesized by thermal processing of trichlorosilane-derived sol-gel glasses followed by HF etching and surface passivation with alkyl chains and were subsequently fractionated by size using a self-generating density gradient of 40 wt % 2,4,6-tribromotoluene in chlorobenzene. The isolated monodisperse fractions were characterized by photoluminescence spectroscopy and high-angle annular dark-field scanning transmission electron microscopy and determined to have polydispersity index values between 1.04 and 1.06. The ability to isolate monodisperse ncSi will allow for the quantification of the size-dependent structural, optical, electrical, and biological properties of silicon, which will undoubtedly prove useful for tailoring property-specific optoelectronic and biomedical devices.
authors: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.
authors: Melanie L
authors: ML
authors: Mastronardi
authors: Frank
authors: F
authors: Hennrich
authors: Eric J
authors: EJ
authors: Henderson
authors: Florian
authors: F
authors: Maier-Flaig
authors: Carolin
authors: C
authors: Blum
authors: Judith
authors: J
authors: Reichenbach
authors: Uli
authors: U
authors: Lemmer
authors: Christian
authors: C
authors: Kübel
authors: Di
authors: D
authors: Wang
authors: Manfred M
authors: MM
authors: Kappes
authors: Geoffrey A
authors: GA
authors: Ozin
mesh_terms: D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties; D014461:Ultracentrifugation
chemical_list: D012825:Silicon