4 research outputs found
Structure and Optical Properties of Self-Assembled Multicomponent Plasmonic Nanogels
Multicomponent plasmonic nanogels (PNGs) capable of broadband absorption of light in the 400-700 nm wavelength range were synthesized by the self-assembly of metal nanoparticles with wormlike surfactant micelles. Small angle x-ray scattering and rheological experiments suggest that the nanoparticles bridge micelle fragments to aid the formation a stable gel phase with exceptional color uniformity. Their optical absorbance could be robustly tuned by changing the nanoparticle type (Au/Ag), size, shape, and/or concentration. The PNGs have relatively low viscosity and are thermoreversible. Potential applications to the manufacturing of coatings and interfaces for solar energy harvesting and reconfigurable optical devices can be envisioned
Plasmonic Nanogels with Robustly Tunable Optical Properties
Low viscosity fluids with tunable optical properties can be processed to manufacture thin film and interfaces for molecular detection, light trapping in photovoltaics and reconfigurable optofluidic devices. In this work, self-assembly in wormlike micelle solutions is used to uniformly distribute various metallic nanoparticles to produce stable suspensions with localized, multiple wavelength or broad-band optical properties. Their spectral response can be robustly modified by varying the species, concentration, size and/or shape of the nanoparticles. Structure, rheology and optical properties of these plasmonic nanogels as well as their potential applications to efficient photovoltaics design are discussed
Effective permittivity of random plasmonic composites
An effective-medium theory (EMT) is developed to predict the effective
permittivity \epsilon_eff of dense random dispersions of high
optical-conductivity metals such as Ag, Au and Cu. Dependence of \epsilon_eff
on the volume fraction \phi, a microstructure parameter \kappa related to the
static structure factor and particle radius a is studied. In the electrostatic
limit, the upper and lower bounds of \kappa correspond to Maxwell-Garnett and
Bruggeman EMTs respectively. Finite size effects are significant when
|\beta^2(ka/n)^3| becomes O(1) where \beta, k, and n denote the nanoparticle
polarizability, wavenumber and matrix refractive index respectively. The
coupling between the particle and effective medium results in a red-shift in
the resonance peak, a non-linear dependence of \epsilon_eff on \phi, and Fano
resonance in \epsilon_eff.Comment: Manuscript submitted to J. Opt. Soc. Am. B. 33 page