Probing electron transport in plasmonic molecular junctions with two-photon luminescence spectroscopy

Qiang Zhang, Danjun Liu, Qun Ren, Nicolae C. Panoiu, Li Lin, Jian Ye, Yang Huang, Shao Ding Liu, Chi Wah Leung, Dangyuan Lei

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Plasmonic core-molecule-shell (CMS) nanojunctions provide a versatile platform for studying electron transport through conductive molecules under light excitation. In general, the impact of electron transport on the near-field response of CMS nanojunctions is more prominent than on the far-field property. In this work, we use two-photon luminescence (TPL) spectroscopy to probe the effect of electron transport on the plasmonic properties of gold CMS nanojunctions. Theoretical calculations show that the TPL response of such nanojunctions is closely related to the near-field enhancement inside the metal regions, and can be strongly affected by the electron transport through the embedded molecules. TPL excitation spectroscopy results for three CMS nanojunctions (0.7, 0.9 and 1.5 nm junction widths) reveal no perceivable contribution from their low-energy plasmon modes. This observation can be well explained by a quantum-corrected model, assuming significant conductance for the molecular layers and thus efficient charge transport through the junctions. Furthermore, we explore the charge transport mechanism by investigating the junction width dependent TPL intensity under a given excitation wavelength. Our study contributes to the field of molecular electronic plasmonics through opening up a new avenue for studying quantum charge transport in molecular junctions by non-linear optical spectroscopy.

Original languageEnglish
Pages (from-to)2467-2479
Number of pages13
JournalNanophotonics
Volume10
Issue number9
DOIs
Publication statusPublished - 1 Jul 2021

Keywords

  • electron transport
  • molecular electronic plasmonics
  • molecular junctions
  • two-photon luminescence spectroscopy

ASJC Scopus subject areas

  • Biotechnology
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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