Radical Initiated Hydrosilylation on Silicon Nanocrystal Surfaces: An Evaluation of Functional Group Tolerance and Mechanistic Study

Abstract

Hydrosilylation is among the most common methods used for modifying silicon surface chemistry. It provides a wide range of surface functionalities and effective passivation of surface sites. Herein, we report a systematic study of radical initiated hydrosilylation of silicon nanocrystal (SiNC) surfaces using two common radical initiators (i.e., 2,2'-azobis(2-methylpropionitrile) and benzoyl peroxide). Compared to other widely applied hydrosilylation methods (e.g., thermal, photochemical, and catalytic), the radical initiator based approach is particle size independent, requires comparatively low reaction temperatures, and yields monolayer surface passivation after short reaction times. The effects of differing functional groups (i.e., alkene, alkyne, carboxylic acid, and ester) on the radical initiated hydrosilylation are also explored. The results indicate functionalization occurs and results in the formation of monolayer passivated surfaces.

Origin of the Photoluminescence Quantum Yields Enhanced by Alkane-Termination of Freestanding Silicon Nanocrystals: Temperature-Dependence of Optical Properties

“…One common nonradiative channel is definitely the defect/trap state formed at the interface between the surface oxide and ncSi for both samples (see the ATR-FTIR spectra). Although it is difficult to make a quantitative comparison in the amount of surface oxide between ncSi:H and ncSi-OD, the surface of ncSi-OD would be expected to contain far higher levels of oxide than that of ncSi:H because of a lower packing density of alkyl monolayers relative to hydrogen atoms56. Nevertheless, we see the rapid decrease of PL intensity with temperature for ncSi:H rather than for ncSi-OD.…”

Lewis Acid Protection: A Method Toward Synthesizing Phase Transferable Luminescent Silicon Nanocrystals

“…H‐Si‐NCs (25 mg) were dispersed in 15 mL of dry toluene containing 0.48 mmol of azobisisobutyronitrile (AIBN) in a Schlenk flask. N′‐undec‐10‐enyl‐N,N‐dimethylacetamidine (10 mmol) was added to a second Schlenk flask . The contents of both flasks were subjected to 3 freeze‐pump‐thaw cycles.…”

Highly photoluminescent and stable silicon nanocrystals functionalized via microwave-assisted hydrosilylation

“…There are two the promising methods to produce large quantities of luminescent Si-NCs, namely synthesis in a nonthermal plasma reactor or high temperature disproportionation reaction of silicon oxide based materialssilicon monoxide SiO x or hydrogen silsesquioxanes (HSiO 1.5 ) nand subsequent functionalization of the hydrogen capped nanocrystals (H-Si-NCs) with organic ligands. [3][4][5][6][7][8][9][10][11][12] The functionalization of Si-NCs relies on radical hydrosilylation reactions, initiated by temperature, light or radical initiators. The functionalization is necessary as it signicantly increases the PLQY and chemical stability of the Si-NCs.…”