Nano Lett. 2016 Feb 10;16(2):1472-7. doi: 10.1021/acs.nanolett.5b05142. Epub 2016 Jan 29.

Broadband Absorbing Exciton-Plasmon Metafluids with Narrow Transparency Windows.

Nano letters

Jihua Yang, Nicolaas J Kramer, Katelyn S Schramke, Lance M Wheeler, Lucas V Besteiro, Christopher J Hogan, Alexander O Govorov, Uwe R Kortshagen

PMID: 26808215 DOI: 10.1021/acs.nanolett.5b05142

Abstract

Optical metafluids that consist of colloidal solutions of plasmonic and/or excitonic nanomaterials may play important roles as functional working fluids or as means for producing solid metamaterial coatings. The concept of a metafluid employed here is based on the picture that a single ballistic photon, propagating through the metafluid, interacts with a large collection of specifically designed optically active nanocrystals. We demonstrate water-based metafluids that act as broadband electromagnetic absorbers in a spectral range of 200-3300 nm and feature a tunable narrow (∼100 nm) transparency window in the visible-to-near-infrared region. To define this transparency window, we employ plasmonic gold nanorods. We utilize excitonic boron-doped silicon nanocrystals as opaque optical absorbers ("optical wall") in the UV and blue-green range of the spectrum. Water itself acts as an opaque "wall" in the near-infrared to infrared. We explore the limits of the concept of a "simple" metafluid by computationally testing and validating the effective medium approach based on the Beer-Lambert law. According to our simulations and experiments, particle aggregation and the associated decay of the window effect are one example of the failure of the simple metafluid concept due to strong interparticle interactions.

Keywords: Colloidal boron-doped silicon nanocrystals; exciton−plasmon metafluid; gold nanorods; transparency window

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't
• Research Support, U.S. Gov't, Non-P.H.S.