Eco-friendly Approach for Creation of Resonant Silicon Nanoparticle Colloids

Abstract

The commercial application of Mie-resonant nanophotonic technologies currently used in various laboratory studies, from biosensing to quantum optics, appears to be challenging. Development of colloidal-based fabrication approaches is a solution to face the issue. In our research, we studied the fabrication of resonant Si nanoparticle (NP) arrays on a surface with controlled wettability. First, we use nanosecond (ns) laser ablation in water and subsequent density gradient separation to obtain colloids of resonant spherical crystalline silicon NPs with a low polydispersity index. Then, the same industrial ns laser is applied to create a wetting gradient on the steel substrate to initiate a self-assembly of the NPs deposited by drop casting. Thus, we use a single commercial ns laser for producing both the NPs and the hydrophilic wetting gradient. We apply an easily operating size separation technique and only non-toxic media. This research contributes to the large-scale fabrication of various optical devices based on resonant high-refractive index nanostructures by ecologically friendly self-assembly techniques.

Single-Step Fabrication of Resonant Silicon–Gold Hybrid Nanoparticles for Efficient Optical Heating and Nanothermometry in Cells

“…Resonant dielectric Si NPs were fabricated using the laser ablation in liquid (LAL) method. ,, This approach is environmentally friendly due to the absence of toxic chemical reagents; it is also straightforward and can be scaled for mass production . Moreover, this method allows control over the shape, size, and morphology of the fabricated NPs by varying the irradiation laser parameters.…”

“…However, for efficient heat generation, such resonant dielectric NPs (e.g., Si NPs) should have a narrow size distribution for scattering and absorption to be balanced to meet the critical coupling condition . A conventional approach for the fabrication of crystalline Si NPs is laser ablation; however, it suffers from polydisperse outcomes as there is a lack of full control over the fabrication procedure. , Therefore, to apply Si NPs obtained with this method for heating purposes, they should be additionally size-separated (e.g., using a density gradient), and further, the fraction of NPs with required sizes should be extracted …”

Au–Si Nanocomposites with High Near-IR Light-to-Heat Conversion Efficiency via Single-Step Reactive Laser Ablation of Porous Silicon for Theranostic Applications

“…The product obtained by LAL is usually characterized by a rather broad bimodal size distribution, , while separation of nanoparticles to the desired size requires suspension post-treatment, which can make the product contamination unsuitable for subsequent applications without challenging purification. − In this respect, expansion of the pathways to control the size and homogeneity of the synthesized products during LAL synthesis is crucial for further development of this technique toward realistic applications. Key laser parameters (such as a wavelength or a repetition rate, as well as a pulse energy, duration, and sequence) are naturally tuned to modify the resulting product size.…”

Understanding the Formation Mechanisms of Silicon Particles from the Thermal Disproportionation of Hydrogen Silsesquioxane

“…Applications of resonant Si particles include anticounterfeit labels, nonlinear nanophotonics, and enhanced Raman scattering, , among others. Optimizing a bottom-up synthesis method to easily obtain resonant units with the desired characteristics could open pathways toward large-scale fabrication of highly efficient metamaterials. , One of the most promising fabrication methods currently available is the thermal disproportionation of silicon-rich oxide compounds, in particular hydrogen silsesquioxane (HSQ), [HSiO 3/2 ] n , producing objects that fully possess the desired criteria for resonant silicon particles. − The main drawbacks of this synthesis are that the synthesis occurs at very high temperatures, and thus is energy-intensive, and that the particles produced are polydisperse in size, and thus need to undergo a size separation process in order to obtain a monodisperse sample. ,, Perhaps by understanding the particle formation mechanism, it would be possible either to decrease the polydispersity or to decrease the energy requirements of this synthetic approach.…”