Synthesis and Ligand Exchange of Thiol-Capped Silicon
Nanocrystals
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Abstract
Hydride-terminated silicon (Si) nanocrystals
were capped with dodecanethiol
by a thermally promoted thiolation reaction. Under an inert atmosphere,
the thiol-capped nanocrystals exhibit photoluminescence (PL) properties
similar to those of alkene-capped Si nanocrystals, including size-tunable
emission wavelength, relatively high quantum yields (>10%), and
long
radiative lifetimes (26–280 μs). X-ray photoelectron
spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy
confirmed that the ligands attach to the nanocrystal surface via covalent
Si–S bonds. The thiol-capping layer, however, readily undergoes
hydrolysis and severe degradation in the presence of moisture. Dodecanethiol
could be exchanged with dodecene by hydrosilylation for enhanced stability