Silyl Radical Abstraction in the Functionalization of Plasma-Synthesized Silicon Nanocrystals

Lance M. Wheeler, Nicholas C. Anderson, Peter K.B. Palomaki, Jeffrey L. Blackburn, Justin C. Johnson, Nathan R. Neale

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61 Scopus Citations


Many silicon nanostructures have exhibited favorable optical properties following surface functionalization with molecular groups through a silicon-carbon bond. Here, we show the mechanism of functionalization of silicon nanocrystals synthesized in a nonthermal radiofrequency plasma is fundamentally different than in other silicon systems. In contrast to hydrosilylation, where homolytic cleavage of Si-H surface bonds is typically a prerequisite to functionalization, we demonstrate the dominant initiation step for plasma-synthesized silicon nanocrystals is abstraction of a silyl radical, ·SiH3, and generation of radical at the silicon nanocrystal surface. We experimentally trap the abstracted silyl radical and show this initiation mechanism occurs for both radical- and thermally-initiated reactions of alkenes using complementary FTIR and 1H NMR spectroscopies. These data additionally indicate that silylsilylation, addition of a Si-SiH3 group across an unsaturated hydrocarbon, competes with hydrosilylation. We also present a new empirical sizing curve as a convenient method to determine Si NC size from photoluminescence peak energy.

Original languageAmerican English
Pages (from-to)6869-6878
Number of pages10
JournalChemistry of Materials
Issue number19
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-62520


  • hydrosilylation
  • nanocrystals
  • optical properties
  • silicon nanostructures
  • silylsilylation
  • solar-photochemistry


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