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Unveiling the Potential of Redox Chemistry to Form Size-Tunable, High-Index Silicon Particles
Megan A Parker1, Safa Khaddad1, Nicolas Fares2
1University of Bordeaux, CNRS, Bordeaux-INP, ICMCB, UMR 5026, F-33600 Pessac, France.
Chemistry of Materials : a Publication of the American Chemical Society
|December 2, 2024
Summary
Chemists developed a new solution synthesis for silicon nanoparticles (45-230 nm). These tunable silicon particles exhibit a high refractive index, showing promise for advanced optical devices and light manipulation applications.
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- Silicon particles in the 75-200 nm range scatter visible light, making them suitable for optical applications.
- Solution synthesis of silicon particles within this size range has been a long-standing challenge.
Purpose of the Study:
- To develop a controllable solution-phase synthesis for silicon nanoparticles.
- To achieve size tunability in silicon particle synthesis.
- To characterize the optical and surface properties of the synthesized silicon particles.
Main Methods:
- Solution-phase reaction between a silicon Zintl phase (Na4Si4) and an amidinate-stabilized Si(IV) complex.
- Powder X-ray diffraction to determine coherent domain sizes.
- Surface analysis using ToF-SIMS, FTIR, and X-ray photoelectron spectroscopy.
- Holographic optical microscopy to measure refractive index.
Main Results:
- Achieved size tunability of silicon particles between 45 and 230 nm by adjusting reactant ratios.
- Crystallite sizes were uniform across all particle sizes, suggesting an aggregation growth mechanism.
- Confirmed the presence of amidinate ligands, primary amine, and a passive oxidation layer on particle surfaces.
- Measured a high refractive index of approximately 4.1 at 532 nm for individual particles.
Conclusions:
- The developed solution synthesis offers a pathway to size-tunable silicon nanoparticles.
- The synthesized particles possess properties suitable for intense light scattering in the visible spectrum.
- These silicon nanoparticles are promising candidates for optical devices and manipulation.
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