Broadband, Angle- and Polarization-Invariant Antireflective and Absorbing Films by a Scalable Synthesis of Monodisperse Silicon Nanoparticles

Parker R. Wray, Mohammad Ali Eslamisaray, Gunnar M. Nelson, Ognjen Ilic, Uwe R. Kortshagen, Harry A. Atwater

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Optically induced magnetic resonances (OMRs) are highly tunable scattering states that cannot be reproduced in systems that only support electric resonances, such as in metals, lossy, or low-index materials. Despite offering unique scattering and coupling behavior, the study of OMRs in thin films has been limited by synthesis and simulation constraints. We report on the absorption and scattering response of OMR-based thin films composed of monodisperse crystalline silicon nanoparticles synthesized using a scalable nonthermal plasma growth technique and tractable simulation framework. The synthesis is solvent and ligand free, ensuring minimal contamination, and crystalline particles form with high yield and a narrow size distribution at close to room temperature. Using a scalable high-throughput deposition method, we deposit random particle films, without the need of a solid host matrix, showing near complete blackbody absorption at the collective OMR. This is achieved using 70% less material than an optimized antireflective-coated crystalline silicon thin film. The film exhibits strongly directional forward scattering with very low reflectivity, thus giving rise to angle- and polarization-insensitive antireflection properties across the visible spectrum. We find that, while commonly used effective medium models cannot capture the optical response, a modified effective medium accounting for multipole resonances and interparticle coupling shows excellent agreement with experiment. The effective permittivity and permeability are written in a mode and cluster resolved form, providing useful insight into how individual resonances and nanoparticle clusters affect the overall film response. Electric and magnetic-mode coupling show dramatically different behavior, resulting in uniquely different spectral broadening.

Original languageEnglish (US)
Pages (from-to)23624-23636
Number of pages13
JournalACS Applied Materials and Interfaces
Volume14
Issue number20
DOIs
StatePublished - May 25 2022

Bibliographical note

Funding Information:
This work is supported by the Army Research Office under MURI project under W911NF-18-1-0240. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nanotechnology Coordinated Infrastructure (NNCI) under Award Number ECCS-2025124. O.I. also acknowledges support from the 3M Foundation through the 3M Non-Tenured Faculty Award grant.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

Keywords

  • absorber
  • antireflection
  • films
  • nanocrystals
  • nanoparticles
  • optical magnetic resonance
  • plasma

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