Dynamic Control of the Interparticle Distance in a Self-Assembled Ag Nanocube Monolayer for Plasmonic Color Modulation

We experimentally demonstrated plasmonic color modulation by dynamically controlling the plasmon resonance excited in an assembled Ag nanocube (AgNC) monolayer. The plasmon resonance wavelength of the hybridization plasmon mode of the local plasmon and collective oscillation plasmon in the Ag nanocube monolayer is sensitive to the interparticle distances. The interparticle distances were continuously controlled with a stretchable and transparent polydimethylsiloxane (PDMS) substrate. Crystalline Ag nanocubes were synthesized through a polyol process. The nanocube shape provides a narrower plasmon resonance band as a result of the small dispersion of electron vibrations. The synthesized nanocubes were densely assembled in a monolayer on the PDMS substrate using the Langmuir–Blodgett (LB) method. The interparticle distance of the Ag nanocube monolayer was controlled from 5.8 to 24.8 nm through biaxial stretching of the substrate from 0 to 20%. The transmitted light color of the Ag nanocube monolayer was actively tuned from magenta to orange to yellow by stretching the substrate up to 20% under random polarization incidence. This color modulation was generated by the plasmon resonance transition from the collective oscillation mode between particles to the local oscillation mode in the isolated nanocubes. Such a plasmonic color modulation is expected to enable a multispectral image sensor with compact and high light utilization efficiency.