Exciton-plasmon interaction in a composite metal-insulator-semiconductor nanowire system

We report about the synthesis and optical properties of a composite metal-insulator-semiconductor nanowire system which consists of a wet-chemically grown silver wire core surrounded by a SiO₂ shell of controlled thickness, followed by an outer shell of highly luminescent CdSe nanocrystals. With microphotoluminescence (μ-PL) experiments, we studied the exciton-plasmon interaction in individual nanowires and analyzed the spatially resolved nanocrystal emission for different nanowire length, SiO ₂-shell thickness, nanocrystal shape, pump power, and emission polarization. For an SiO₂ spacer thickness of ∼15 nm, we observed an efficient excitation of surface plasmons by excitonic emission of CdSe nanocrystals. For nanowire lengths up to ∼10 μm, the composite metal-insulator-semiconductor nanowires ((Ag)SiO₂)CdSe act as a waveguide for 1D-surface plasmons at optical frequencies with efficient photon outcoupling at the nanowire tips, which is promising for efficient exciton-plasmon-photon conversion and surface plasmon guiding on a submicron scale in the visible spectral range.