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

Autor: Zhang Qiang, Liu Danjun, Ren Qun, Panoiu Nicolae C., Lin Li, Ye Jian, Huang Yang, Liu Shao-Ding, Leung Chi Wah, Lei Dangyuan
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Nanophotonics, Vol 10, Iss 9, Pp 2467-2479 (2021)
Druh dokumentu: article
ISSN: 2192-8606
2192-8614
2021-0116
DOI: 10.1515/nanoph-2021-0116
Popis: 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.
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