Bright NIR-II Photoluminescence in Rod-Shaped Icosahedral Gold Nanoclusters

Qi Li*, Charles J. Zeman, Zhuoran Ma, George C. Schatz, X. Wendy Gu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Fluorophores with high quantum yields, extended maximum emission wavelengths, and long photoluminescence (PL) lifetimes are still lacking for sensing and imaging applications in the second near-infrared window (NIR-II). In this work, a series of rod-shaped icosahedral nanoclusters with bright NIR-II PL, quantum yields up to ≈8%, and a peak emission wavelength of 1520 nm are reported. It is found that the bright NIR-II emission arises from a previously ignored state with near-zero oscillator strength in the ground-state geometry and the central Au atom in the nanoclusters suppresses the non-radiative transitions and enhances the overall PL efficiency. In addition, a framework is developed to analyze and relate the underlying transitions for the absorptions and the NIR-II emissions in the Au nanoclusters based on the experimentally defined absorption coefficient. Overall, this work not only shows good performance of the rod-shaped icosahedral series of Au nanoclusters as NIR-II fluorophores, but also unravels the fundamental electronic transitions and atomic-level structure-property relations for the enhancement of the NIR-II PL in gold nanoclusters. The framework developed here also provides a simple method to analyze the underlying electronic transitions in metal nanoclusters.

Original languageEnglish (US)
Article number2007992
JournalSmall
Volume17
Issue number11
DOIs
StatePublished - Mar 18 2021

Keywords

  • electronic transitions
  • gold nanoclusters
  • NIR-II emissions
  • structure-property relations

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Chemistry(all)
  • Materials Science(all)

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