Switchable Organic Plasmonics with Conductive Polymer Nanoantennas

TL;DR

This paper introduces conductive polymer nanostructures as a new class of organic plasmonic nanoantennas that can be dynamically tuned via redox chemistry, enabling adaptable nano-optical devices.

Contribution

The study demonstrates that conductive polymers can serve as redox-tuneable plasmonic nanoantennas, offering a flexible alternative to traditional metal-based nanooptics.

Findings

Polymer nanodisks exhibit clear localized surface plasmon resonances.

Resonance frequencies shift with nanodisk aspect ratio, matching theoretical predictions.

Complete optical switching achieved through chemical redox tuning of the polymer.

Abstract

Metal nanostructures are key elements in nanooptics owing to their strong resonant interaction with light through local plasmonic charge oscillations. Their ability to shape light at the nanoscale have made them important across a multitude of areas, including biosensing, energy conversion and ultrathin flat metaoptics. Yet another dimension of avenues is foreseen for dynamic nanoantennas, ranging from tuneable metalenses for miniaturized medical devices to adaptable windows that control radiation flows in and out of buildings. However, enabling nano-optical antennas to be dynamically controllable remains highly challenging and particularly so for traditional metals with fixed permittivity. Here we present state-of-the-art conductive polymers as a new class of organic plasmonic materials for redox-tuneable nano-optics. Through experiments and simulations, we show that nanodisks of highly conductive polymers can provide clear optical extinction peaks via excitation of dipolar localised surface plasmon resonances. Resonance frequencies redshift with increasing nanodisk aspect ratio, in agreement with analytical calculations based on dipolar polarizability theory. We furthermore demonstrate complete switching of the optical response of the organic nanoantennas by chemical tuning of the polymer's redox state, which effectively modulates the material permittivity between plasmonic and non-plasmonic regimes. Our results thereby show that conductive polymer nanostructures can act as redox-tuneable plasmonic nanoantennas, based on bipolaronic charge carriers rather than electrons as in conventional metals. Future directions may investigate different polymers and geometries to further widen the plasmonic spectral range (here around 0.8 to 3.6 {\mu}m) as well as different ways of tuning.