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Thickness-Dependent Charge Transport in Three Dimensional Ru(II)- Tris(phenanthroline)-Based Molecular Assemblies.

Authors :
Gupta R
Bhandari S
Kaya S
Katin KP
Mondal PC
Source :
Nano letters [Nano Lett] 2023 Dec 13; Vol. 23 (23), pp. 10998-11005. Date of Electronic Publication: 2023 Dec 04.
Publication Year :
2023

Abstract

We describe here the fabrication of large-area molecular junctions with a configuration of ITO/[Ru(Phen) <subscript>3</subscript> ]/Al to understand temperature- and thickness-dependent charge transport phenomena. Thanks to the electrochemical technique, thin layers of electroactive ruthenium(II)-tris(phenanthroline) [Ru(Phen) <subscript>3</subscript> ] with thicknesses of 4-16 nm are covalently grown on sputtering-deposited patterned ITO electrodes. The bias-induced molecular junctions exhibit symmetric current-voltage (j-V) curves, demonstrating highly efficient long-range charge transport and weak attenuation with increased molecular film thickness (β = 0.70 to 0.79 nm <superscript>-1</superscript> ). Such a lower β value is attributed to the accessibility of Ru(Phen) <subscript>3</subscript> molecular conduction channels to Fermi levels of both the electrodes and a strong electronic coupling at ITO-molecules interfaces. The thinner junctions (d = 3.9 nm) follow charge transport via resonant tunneling, while the thicker junctions (d = 10-16 nm) follow thermally activated (activation energy, E <subscript>a</subscript> ∼ 43 meV) Poole-Frenkel charge conduction, showing a clear "molecular signature" in the nanometric junctions.

Details

Language :
English
ISSN :
1530-6992
Volume :
23
Issue :
23
Database :
MEDLINE
Journal :
Nano letters
Publication Type :
Academic Journal
Accession number :
38048073
Full Text :
https://doi.org/10.1021/acs.nanolett.3c03256