Non-wettable, Oxidation-Stable, Brightly Luminescent, Perfluorodecyl-Capped Silicon Nanocrystal Film

Abstract

Here we describe for the first time the synthesis of colloidally stable, brightly luminescent perfluorodecylcapped silicon nanocrystals and compare the properties of solutions and films made from them with those of their perhydrodecyl-capped relatives. The perfluorodecyl capping group compared to the perhydrodecyl capping group yields superior hydrophobicity and much greater resistance to air oxidation, the enhanced electron-withdrawing character induces blue shifts in the wavelength of photoluminescence, and the lowerfrequency carbon-fluorine stretching modes disfavor non-radiative relaxation pathways and boost the absolute photoluminescence quantum yield. Together these attributes bode well for advanced materials and biomedical applications founded upon perfluorodecyl-protected silicon nanocrystals. Keywordscapped, perfluorodecyl, luminescent, brightly, stable, oxidation, wettable, nanocrystal, non, silicon, film Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsQian, C., Sun, W., Wang, L., Chen, C., Liao, K., Wang, W., Jia, J., Hatton, B., Casillas, G., Kurylowicz, M., Yip, Supporting Information PlaceholderABSTRACT: Here we describe for the first time the synthesis of colloidally-stable, brightly-luminescent perfluorodecylcapped silicon nanocrystals and compare the properties of solutions and films with the perhydrodecyl-capped relative. The perfluorodecyl capping group compared to the perhydrodecyl capping group yields superior hydrophobicity and much greater resistance to air oxidation, the enhanced electron withdrawing character induces blue shifts in the wavelength of photoluminescence and the lower frequency carbon-fluorine stretching modes disfavor non-radiative relaxation pathways and boost the absolute photoluminescence quantum yield. Together these attributes bode well for advanced materials and biomedical applications founded upon perfluorodecyl-protected silicon nanocrystals.The burgeoning research activity on new kinds of nanostructured silicon, made from one of the most abundant and green materials on earth, is striking.

Silicon Nanocrystals and Silicon‐Polymer Hybrids: Synthesis, Surface Engineering, and Applications

“…[40] Perfluorodecyl groups were grafted onto Si-NC surfaces upon heating in am icrowave reactor (Scheme 2). [40] Perfluorodecyl groups were grafted onto Si-NC surfaces upon heating in am icrowave reactor (Scheme 2).…”

Silicon monoxide – a convenient precursor for large scale synthesis of near infrared emitting monodisperse silicon nanocrystals

“…Note that this synthesis approach has several advantages over the (HSiO 1.5 ) n precursor, which was synthesized from HSiCl 3 and processed with several steps before HF etching. [45][46][47] Table 1 lists several comparisons between the two methods. The origin of the relatively low yield of ncSi:H product for both methods we believe is during the aqueous HF extraction and transfer of the dispersion to the organic solvent, however the yield of ncSi:H from the SiO precursor is consistently higher than (HSiO 1.5 ) n due to the higher atom ratio of Si, and the experimental procedure is much easier to manage.…”

Silicon Nanocrystals: It's Simply a Matter of Size

“…The growing interest in the surface modification of hydride‐terminated silicon nanocrystals (ncSi:H) with organic functional groups is accompanied by the realization of much improved colloidal stability, in polar or non‐polar solvents . Notably, recent developments aimed at chemically functionalizing the surface with perfluorinated ligands have provided silicon nanocrystals with impressive superhydrophobicity, air stability and luminescence efficiency when fashioned as a film . In general, the surface chemistry of ncSi is designed to endow them with processability and functionality.…”

“…To minimize air oxidation, protection of the ncSi surface is essential. As mentioned earlier, perfluorinated ligands help exclude water from the ncSi surface ameliorating the effects of oxidation . Matrix encapsulation to form nanocomposites has also been used to protect ncSi against adventitious air oxidation effects …”