Plasmonic nanoclusters based on conjugated polymer for controlled optical output

Rational design and assembly of colloidal metal nanoparticles with fluorescent materials like organic dyes, conjugated polymers or colloidal quantum dots has stimulated intense research interest in the past decade in view of obtaining nanomaterials with controllable optical properties and with applicability in optoelectronics and biosensing. The interaction between a fluorescent molecule and a metal nanoparticle, also known as plasmon-exciton interaction, is determined by several factors such as type, shape and size of the metal nanoparticle, electronic properties of the fluorescent molecule, metal nanoparticle-fluorescence molecule separation distance and local nanoenvironment. By tuning one or more of such factors one can achieve control of the plasmon-exciton interaction and therefore of the optical output. This research reports assembly by electrostatic binding and the single particle characterization of a series of plasmonic nanoclusters based on core/shell Au/SiO2 nanoparticle capped with a water soluble conjugated polythiophene derivative. By varying the thickness of the SiO2 spacer we demonstrate the ability to control the photoluminescence output of the metal nanoparticle/conjugated polymer nanocluster. Plasmonic nanoclusters exhibiting enhanced photoluminensce were further conjugated with Cytochrome C to investigate plasmon-assisted photoinduced charge transfer from the polymer to Cytochrome C.