Tunable Electrochemical Switch of the Optical Properties of Metallic Nanoparticles

Abstract

Control of the optical properties of metallic nanoparticles (NP) is realized using an electrochemical switch consisting of a thin layer of conducting polymer (CP). Reversible modulation and almost total quenching of the localized surface plasmon resonance(LSPR) is achieved as a function of the thickness of the CP layer and the potential applied to the electrochemical systems, i.e. the charge carrier density injected into the CP layer. The quenching of LSP also depends of the frequency of the LSPR. This effect is attributed to the variation of the CP dielectric function with wavelength. As a consequence, prolate arrays show total quenching of the LSPR along the major axis of the particles whereas modulation and moderate damping are observed along the minor axis. We believe that combining an electroactive conducting polymer and NP will prove to be a general strategy for controlling the properties of various types of NP (fluorescent, magnetic, semiconducting).