title: Design of Hybrid Electrochromic Materials with Large Electrical Modulation of Plasmonic Resonances.
abstract: We present a rational approach to fabricating plasmonically active hybrid polymer-metal nanomaterials with electrochemical tunability of the localized surface plasmon resonances (LSPRs) of noble metal nanostructures embedded in an electroactive polymer matrix. The key requirement for being able to significantly modulate the LSPR band position is a close overlap between the refractive index change [Δn(λ)] of a stimuli-responsive polymeric matrix and the intrinsic LSPR bands. For this purpose, gold nanorods with a controlled aspect ratio, synthesized to provide high refractive index sensitivity while maintaining good oxidative stability, were combined with a solution-processable electroactive and electrochromic polymer (ECP): alkoxy-substituted poly(3,4-propylenedioxythiophene) [PProDOT(CH2OEtHx)2]. Spectral characteristics of the ECP, in particular the Δn(λ) variation, were evaluated as the material was switched between oxidized and reduced states. We fabricated ultrathin plasmonic electrochromic hybrid films consisting of gold nanorods and ECP that exhibited a large, stable, and reversible LSPR modulation of up to 25-30 nm with an applied electrical potential. Finite-difference time-domain (FDTD) simulations confirm a good match between the experimentally measured refractive index change in the ECP and the plasmonic response during electrochemical modulations.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
authors.forename: Petr A
authors.initials: PA
authors.lastname: Ledin
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
authors.forename: Ju-Won
authors.initials: JW
authors.lastname: Jeon
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Geldmeier
authors.affiliation: School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, and Georgia Tech Polymer Network, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Ponder
authors.affiliation: Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Mahmoud
authors.affiliation: Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
authors.forename: Mostafa
authors.initials: M
authors.lastname: El-Sayed
authors.affiliation: School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, and Georgia Tech Polymer Network, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Reynolds
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Tsukruk
keywords: electroactive materials; electrochromic polymer; gold nanorods; localized surface plasmon resonance; tunable plasmonic behavior