Plasmons in photocharged ZnO nanocrystals revealing the nature of charge dynamics

Jacob A. Faucheaux, Prashant Jain

Research output: Contribution to journalArticlepeer-review

Abstract

Localized surface plasmon resonances (LSPRs), known for their fascinating optical properties, have thus far been limited to nanostructures of materials with high steady-state charge carrier densities. Here, we show that even a nonequilibrium charge population can support a LSPR mode. Photocharged zinc oxide (ZnO) nanocrystals show an infrared LSPR, which can be dynamically turned off by discharging via redox activity. It is deduced that the photoinduced LSPR is a collective mode of as few as four conduction band electrons, the least observed thus far. The sustenance of a free-electron plasma in charged ZnO, supported by the LSPR observation, leads us to propose the existence of a many-body excitonic state and suggest a mechanism for previously unresolved charge trapping dynamics in ZnO. The LSPR, which serves as an optical signature of a charged state of the nanoparticle, is also demonstrated as a useful probe of surface redox reactions.

Original languageEnglish (US)
Pages (from-to)3024-3030
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume4
Issue number18
DOIs
StatePublished - Sep 19 2013

Keywords

  • continuum exciton
  • defect luminescence
  • localized surface plasmon resonance
  • plasmonics
  • zinc oxide

ASJC Scopus subject areas

  • Materials Science(all)

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