High-Throughput Screening of Optical Properties of Glass-Supported Plasmonic Nanoparticles Fabricated by Polymer Pen Lithography

Optical applications of plasmonic nanoparticles depend critically on particle properties such as relative proximity, composition, crystallinity, and shape. The most common nanoparticle fabrication techniques, colloidal synthesis and electron beam lithography, allow the tailoring of some of these parameters, yet do not provide control over all of them. Scanning probe block copolymer lithography (SPBCL), a technique that grows nanoparticles on substrates from precisely deposited precursor droplets, merges the advantages of colloidal synthesis and electron beam lithography, and offers high throughput, precise particle positioning, and composition control. A few challenges with the SBCL method remain: fabrication of optically relevant particle sizes on optically transparent supports, and detailed correlation of their optical and morphological properties. Here, we adapt SPBCL to fabricate large arrays of gold nanoparticles on glass supports. The resulting nanoparticles have varying shapes, and at similar to 100 nm in diameter, they support strong plasmon resonances. In order to fully exploit the high-throughput fabrication method, we designed an automated dark-field microscope and correlated the optical behavior to the mechanical properties as determined through electron and pump-probe microscopy. We find that the SPBCL-synthesized nanoparticles are highly crystalline, supporting both plasmon oscillations and mechanical vibrations with lifetimes comparable to colloidal nanospheres. Our work highlights SPBCL as a promising and versatile synthesis approach for plasmonic nanoparticles, leading the way toward extensive screening capabilities for optical properties and hence improved potential applications.

Automated summary

The optical applications of plasmonic nanoparticles rely on properties such as their relative proximity, composition, crystallinity, and shape. The scanning probe block copolymer lithography (SPBCL) technique offers high throughput, precise particle positioning, and composition control. In this study, large arrays of gold nanoparticles with varying shapes were fabricated on glass supports using SPBCL. The resulting nanoparticles exhibited strong plasmon resonances and high crystallinity, supporting both plasmon oscillations and mechanical vibrations with lifetimes comparable to colloidal nanospheres.