Noble metallic nanoparticles and complex nanostructures made of silver or gold are outstanding building blocks in the design of optical sensors or optical absorbers based on localized surface plasmon resonance (LSPR). Recent studies have shown that the strong localized plasmonic fields are of interest for applications spanning surface-enhanced Raman scattering (SERS), optoelectronics, photovoltaics, and nanophotonics. The peak position of the plasmonic resonance can be tuned by the nanoparticle size, shape, composition, and the refractive index of the surrounding medium. Considering the medium, a responsive dielectric environment composed of pH-sensitive polymers, light sensitive materials, photochromic molecules, or conducting polymers is a promising medium for tuning the plasmonic resonance of nanostructures. We demonstrate electrically tunable plasmonic hybrid nanostructures of silver nanocube aggregates combined with a conjugated electrochromic polymer (ECP) with large and reversible shifts of the plasmonic resonances. In contrast to the studies, where the enhanced plasmonic sensitivity is based on passive dielectric refractive index changes in chemical environmental composition, we introduce electrically tunable nanocube-polymer nanostructures with reversible tuning of plasmonic properties. These hybrid materials demonstrate spectacular multi-cyclical reversible tunability of plasmonic optical properties (absorbance and scattering) with an orthogonal plasmonic resonance shifts. A silver nanocube Langmuir-Blodgett (LB) monolayer, which is coated with an electrochromic polymer coating, enables reversible refractive index variation under variable electrical potential, which causes reversible shifts in plasmon resonance peak positions of silver nanocubes. Electrochemical tunability studies with a combination of <i>in-situ</i> spectroscopic measurements and finite-difference time-domain (FDTD) simulations suggest that the significant plasmonic resonance shifts are triggered by the relative variations of environmental refractive index of the ECP coating caused by externally controlled and reversible electrochemically driven oxidation and reduction reactions.

Electrically tunable plasmonic behavior of nanocube-polymer nanomaterials induced by a redox active electrochromic polymer

249th National Meeting (2015)

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