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Silicon Monoxide--A Convenient Precursor for Large Scale Synthesis of Near Infrared Emitting Monodisperse Silicon Nanocrystals

Silicon Monoxide--A Convenient Precursor for Large Scale Synthesis of Near Infrared Emitting Monodisperse Silicon Nanocrystals

Wei Sun, Chenxi Qian, Xiao Sherri Cui, Liwei Wang, Muan Wei, Gilberto Casillas, Amr S Helmy, Geoffrey A Ozin

Nanoscale. 2016 Feb 14;8(6):3678-84.

PMID: 26812126

Abstract:

While silicon nanocrystals (ncSi) embedded in silicon dioxide thin films have been intensively studied in physics, the potential of batch synthesis of silicon nanocrystals from the solid-state disproportionation of SiO powder has not drawn much attention in chemistry. Herein we describe some remarkable effects observed in the diffraction, microscopy and spectroscopy of SiO powder upon thermal processing in the temperature range 850-1100 °C. Quantum confinement effects and structural changes of the material related to the size of the silicon nanocrystals nucleated and grown in this way were established by Photoluminescence (PL), Raman, FTIR and UV-Visible spectroscopy, PXRD and STEM, pinpointing that the most significant disproportionation transformations happened in the temperature range between 900 and 950 °C. With this know-how a high yield synthesis was developed that produced polydispersions of decyl-capped, hexane-soluble silicon nanocrystals predominantly with near infrared (NIR) PL. Using size-selective precipitation, these polydispersions were separated into monodisperse fractions, which allowed their PL absolute quantum yield (AQY) to be studied as a function of silicon nanocrystal size. This investigation yielded volcano-shaped plots for the AQY confirming the most efficient PL wavelength for ncSi to be located at around 820-830 nm, which corresponded to a size of 3.5-4.0 nm. This work provides opportunities for applications of size-selected near infrared emitting silicon nanocrystals in biomedical imaging and photothermal therapy.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP10097286	Silicon monoxide		10097-28-6	Price

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