Toward hyperuniform disordered plasmonic nanostructures for reproducible surface-enhanced Raman spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Plasmonics

Background:

• Block-copolymers (BCP) self-assemble into ordered nanostructures.
• Gold nanoparticles (Au-NPs) exhibit unique plasmonic properties.
• Surface-Enhanced Raman Scattering (SERS) requires precise nanostructure design.

Purpose of the Study:

• To control the self-assembly of gold nanoparticle (Au-NP) clusters using block-copolymers (BCP).
• To investigate the impact of BCP morphology on Au-NP clustering and SERS performance.
• To explore electric field modulation of BCP-directed Au-NP assemblies.

Main Methods:

• Utilized phase separation of poly(styrene)-b-poly(methylmethacrylate) (PS-b-PMMA) BCP on indium tin oxide coated glass.
• Directed Au-NP (4 nm) inclusion into PS-nanodomains via thermal annealing after gold evaporation.
• Applied static electric fields to modulate BCP morphology and Au-NP cluster arrangement.

Main Results:

• Achieved dense clustering of Au-NPs (> 10(4) μm(2)) in a 2D pattern with near-hyperuniform correlations.
• Demonstrated highly reproducible SERS enhancement (std. dev. ~10% over 0.25 cm(2)) due to homogeneous plasmonic patterns.
• Observed electric field-induced alignment of Au-NP clusters into linear chains, enhancing SERS activity but reducing reproducibility.

Conclusions:

• BCP self-assembly provides a robust platform for creating homogeneous, large-area plasmonic nanostructures.
• The resulting Au-NP clusters yield highly reproducible SERS enhancement.
• Electric field control offers a pathway to tune SERS activity and spatial uniformity.