Plasmonic color generation in silver nanocrystal‐over‐mirror films by thermal embedment into a polymer spacer

Abstract

The production of colors by plasmonic nanostructures is an attractive prospect over dyes as they allow ultra‐high resolution, non‐fading colors. Typical techniques for producing plasmonic color patterns such as by electron beam or ion beam lithography are expensive, slow and not well scalable. This work demonstrates a simple, lithography‐free technique for producing plasmonic colors using a silver nanocube (AgNC) based nanoparticle‐over‐mirror (NPoM) system with thermally‐generated colors. AgNC's are deposited over a metal (Au or Ag) film with a polystyrene (PS) dielectric spacer. Upon heating the system past the glass‐transition temperature of PS, the AgNC embed into the polymer, reducing the AgNC/metal film distance. This results in a strong gap‐plasmon that can shift over 200 nm across the visible spectrum during the process. The thermal embedment of AgNC in NPoM systems is tunable across the visible range, producing wide, distinct color palettes depending on the metal film used. This technique can potentially be applied to plasmonic color‐patterning systems to produce high‐resolution microscale or nanoscale patterns over a large area.

Numerical investigation of dynamic plasmonic color generated via photothermal deformation of a metal semi-shell structure

“…The color of a structure can be changed by dynamic wavelength-adjustment processes such as polarization, 3,4) electricity, 5,6) temperature, 7,8) chemical reactions, 9) and mechanical methods, 10) each conferring various advantages over color development by dyeing. However, these processes require electron beam lithography, 3,9) which is limited to small fabrication areas, a complicated fabrication process, 4) electricity for display, 5,6) or stress or deformation.…”

“…10) Some processes are limited to a small coloration range. 7,8) Our group has studied the localized surface plasmon-resonance properties of a metal semi-shell on a nanosphere under photothermal deformation. We showed that the resonance properties change with photothermal deformation of the core-semi-shells, providing a potential means of dynamic wavelength tuning.…”