Highly Chromatic Plasmonic Color Film by Sterical Dispersion of Au Nanoparticles in Polydimethylsiloxane

We discovered that polydimethylsiloxane (PDMS)-coated Au nanoparticle (AuNP) monolayer disperses sterically in PDMS, and it leads to a dramatic color change in the transmitted light before and after PDMS coating (for example, blue to magenta with AuNPs of 50 nm diameter). This color change was attributed to the transition of the AuNP plasmon resonance from the collective to the local modes because the interparticles of the assembled monolayer dispersed sterically over distances of the noninteracting plasmons between the nanoparticles. Here, we developed a plasmonic color film with vividness, flexibility, and angle insensitivity. The AuNP monolayer was prepared on a PDMS substrate via self-assembly. Subsequently, the plasmonic color film was fabricated by dropping and curing the precured PDMS on top of the AuNPs. The plasmonic color film exhibited an incident angle and polarization independence. Furthermore, it showed that the PDMS film stretching modulated the optical density of the film by 38% at the peak wavelength. In addition, films with various colors were fabricated using AuNPs of different sizes and shapes. Films with intermediate colors were also obtained via the colloid mixing process. These plasmonic color films are expected to be applicable for optical filters, color printing, and color palettes.