Making excitonic materials for soft nanophotonics from supramolecular building blocks

  • Samuel T Holder

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Confining light on the nanoscale offers unique physics associated with enhanced light-matter interactions. Metal films and nanostructures can confine light on the nanoscale using plasma oscillations at the surface of the metal. However the optical properties of metals cannot be actively tuned, which prevents the active control of nanoscale light. Two-dimensional materials offer an alternative platform for nanoscale light confinement that could provide active tunability, but are limited by the difficulty of fabricating single monocrystalline layers.

In this thesis I investigate a new group of nanophotonic materials based on self-assembling J-aggregates. I fabricate four different J-aggregate and polymer materials by a common method based on solution processing and spin-coating. I then characterise the optical properties of these films to show that they can support surface exciton polariton modes. Finally I demonstrate coupling to these nanophotonic modes using Fourier imaging spectroscopy in a Kretschmann prism-coupling configuration. This shows that self-assembled J-aggregates can be used as the building blocks for a new group of soft materials that confine light on the nanoscale. Not only this, these are active materials which can both absorb and emit light due to the delocalised excitons supported by J-aggregates. Therefore J-aggregate materials could offer the tunable, active nanophotonics of two-dimensional materials in a more versatile, bulk platform.
Date of Award23 Jun 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorRuth Oulton (Supervisor), Sara Nunez-Sanchez (Supervisor) & John G Rarity (Supervisor)

Keywords

  • J-aggregates
  • photonics
  • nanophotonics
  • Excitons
  • Exciton transport
  • delocalisation
  • Fourier microscope
  • organic material
  • molecular material
  • Ellipsometry
  • surface exciton polariton
  • Polariton
  • Fourier imaging spectroscopy
  • atomic force microscopy
  • cyanine
  • soft materials
  • 2D materials
  • two-dimensional materials
  • enhanced light-matter interaction
  • active materials

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