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Robust Bipolar Light Emission and Charge Transport in Symmetric Molecular Junctions

Author(s):

Ushula M. Tefashe, Quyen Van Nguyen, Frederic Lafole, Jean-Christophe Lacroix, Richard L. McCreery

Journal:

Journal of the American Chemical Society

Year:

2017

Volume:

139

Pages

7436–7439

DOI:

10.1021/jacs.7b02563

Abstract:

Molecular junctions consisting of a Ru-
(bpy)3 oligomer between conducting carbon contacts
exhibit an exponential dependence of junction current on
molecular layer thickness (d) similar to that observed for
other aromatic devices when d < 4 nm. However, when d >
4 nm, a change in transport mechanism occurs which
coincides with light emission in the range of 600−900 nm.
Unlike light emission from electrochemical cells or solidstate films containing Ru(bpy)3, emission is bipolar, occurs
in vacuum, has rapid rise time (<5 ms), and persists for
>10 h. Light emission directly indicates simultaneous hole
and electron injection and transport, possibly resonant due
to the high electric field present (>3 MV/cm). Transport
differs fundamentally from previous tunneling and hopping
mechanisms and is a clear “molecular signature” relating
molecular structure to electronic behavior.

© Molecular Junction Database | University of Southern California. All rights reserved.

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