Silicon nanocrystals (ncSi) below 5 nm in diameter, the exciton size of bulk silicon, exhibit size-dependent photoluminescence (PL) that arises from quantum confinement effects. The chemical, physical and biological properties of nanomaterials like ncSi are not just controlled by size and shape but also by organic molecules that have been chemically anchored to their surfaces, which play a central role in determining the function and utility of nanomaterials. Specifically, ncSi in this size range can be made colloidally stable by functionalizing the surface with covalently bound organic molecules through hydrosilylation of surface silicon hydride bonds with a terminal alkene, an attribute which is beneficial for solution processing of nanocrystal silicon devices. In organic synthesis, microwave heating instead of traditional oil bath heating has often been reported to enhance the rate of chemical reactions. While the kinetics and mechanism of hydrosilylation of silicon wafers and porous silicon have been reported, no quantitative study of ncSi exists in the literature, and neither does direct comparison between the microwave hydrosilylation and oil-bath hydrosilylation. Here we report the hydrosilylation kinetics of hydride-capped ncSi with 1-decene in a microwave reactor compared to a thermal reactor for the first time. It is found that microwave heating has no evident acceleration effect on the hydrosilylation rate relative to conventional thermal heating, suggesting that the reaction mechanism is the same for both methods and the reaction extent would only depend on the temperature and time.

Hydrosilylation kinetics of silicon nanocrystals: Microwave vs. thermal

248th National Meeting (2014)

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