Au-Ag core-shell nanoparticle array by block copolymer lithography for synergistic broadband plasmonic properties

Area of Science:

• Nanotechnology
• Materials Science
• Photonics

Background:

• Metallic nanostructures with localized surface plasmon resonance (LSPR) are crucial in photonics, electronics, and catalysis.
• Core-shell nanostructures offer tunable plasmonic properties but are synthetically challenging.

Purpose of the Study:

• To present a reliable and controllable method for synthesizing highly ordered Au@Ag core-shell nanoparticle arrays.
• To demonstrate the tunable plasmonic properties and enhanced Raman scattering of these core-shell arrays.

Main Methods:

• Utilizing block copolymer lithography to create size-tunable gold (Au) nanodot arrays.
• Employing seeded-shell growth to deposit silver (Ag) shells of varying thickness onto Au nanodots.
• Characterizing the plasmonic resonance and surface-enhanced Raman scattering (SERS) of the resulting Au@Ag arrays.

Main Results:

• Successfully generated uniform, highly ordered Au@Ag core-shell nanoparticle arrays.
• Achieved widely tunable broadband enhancement of plasmonic resonance.
• Demonstrated a surface-enhanced Raman scattering enhancement factor greater than 270 compared to Au nanoparticle arrays.

Conclusions:

• The developed method provides a controllable route to Au@Ag core-shell nanoparticle arrays with superior plasmonic properties.
• These core-shell arrays significantly outperform single-element or alloy nanoparticle arrays in plasmonic enhancement.
• The enhanced SERS activity highlights the potential applications in sensing and spectroscopy.