Silicon nanopowder with a narrow size distribution was synthesized by a simple method, in which amorphous SiO(x) (x < 2) powder as starting material was annealed at high temperature and then etched by hydrofluoric acid (HF). Si nanoparticles thus obtained exhibited emission in the ultraviolet and visible regions under excitation at an energy corresponding to the direct band-gap transition. At the same time, they could be redispersed in various organic solvents such as octanol, toluene, etc., without surfactants or capping molecules on particle surfaces. X-ray diffraction and Fourier transform infrared spectroscopy were used to follow the change of components in the sample during annealing and HF etching processes, and the size distribution and dispersion morphology of the nanoparticles in different solvents were revealed by transmission electron microscopy analysis.
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"Excellent spectroscopic properties, such as high quantum yield, broad absorption window, and narrow fluorescent wavelength, contribute to a rapid development in Si QD research . Nontoxicity to the environment and the use of an economic source material are other two merits for the application of Si QDs in optoelectronics [2,3], solar energy conversion [4,5], biology [6-8], splitting water , etc. Si QDs can be prepared using a variety of techniques such as wet chemical reduction [10-18], metathesis reaction , disproportionation reaction [20,21], thermal annealing of Si-rich SiC , electrochemical etching , plasma synthesis or plasma-enhanced chemical vapor deposition (PECVD) [24-27], and high-temperature hydrogen reduction method [28-32]. Because Si QDs are chemically active, their surface should be passivated for further use. "
[Show abstract][Hide abstract] ABSTRACT: Silicon quantum dots (Si QDs) attract increasing interest nowadays due to their excellent optical and electronic properties. However, only a few optoelectronic organic molecules were reported as ligands of colloidal Si QDs. In this report, N-vinylcarbazole - a material widely used in the optoelectronics industry - was used for the modification of Si QDs as ligands. This hybrid nanomaterial exhibits different spectroscopic properties from either free ligands or Si QDs alone. Possible mechanisms were discussed. This type of new functional Si QDs may find application potentials in bioimaging, photovoltaic, or optoelectronic devices.
Full-text · Article · Aug 2014 · Nanoscale Research Letters
"Liu and colleagues (2005) successfully synthesized luminescent Si nanoparticles which were redispersible in various solvents. The nanoparticles were prepared through annealing and subsequent etching with HF from amorphous SiOx (x<2) powders as starting materials. "
[Show abstract][Hide abstract] ABSTRACT: In this review, we describe the synthesis, physical properties, surface functionalization, and biological applications of silicon nanoparticles (also known as quantum dots). We compare them against current technologies, such as fluorescent organic dyes and heavy metal chalcogenide-based quantum dots. In particular, we examine the many different methods that can be used to both create and modify these nanoparticles and the advantages they may have over current technologies that have stimulated research into designing silicon nanoparticles for in vitro and in vivo applications.
Preview · Article · Feb 2006 · International Journal of Nanomedicine
[Show abstract][Hide abstract] ABSTRACT: Silicon nanoparticles ranging from 2 to 16 nm were synthesized by a facile wet chemical route, in which SiO amorphous powder was annealed at 1000 °C, etched in hydrofluoric acid, and surface modified by alkene. After alkyl-termination of the particle surfaces, size selective precipitation technique was applied to separate the nanoparticles into uniform sized fractions. Transmission electron microscopy showed well-dispersed and highly crystalline silicon nanoparticles after the treatment by alkene. Visible room-temperature photoluminescence in the range 800−500 nm was observed from these nanoparticles. The photoluminescence intensity has significantly been enhanced by the surface functionalization. Moreover, the PL peak energy of the size-selected nanoparticles shifted to blue as the size decreased due to quantum confinement effect. The experimental result was also compared with the theoretical predictions and was found to follow the general trend of the model calculations.
No preview · Article · Jan 2006 · Chemistry of Materials