Robust Bipolar Light Emission and Charge Transport in Symmetric Molecular Junctions

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

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

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 solid-state 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.

Original languageEnglish (US)
Pages (from-to)7436-7439
Number of pages4
JournalJournal of the American Chemical Society
Volume139
Issue number22
DOIs
StatePublished - Jun 7 2017
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the University of Alberta, the National Research Council of Canada, the National Science and Engineering Research Council, and Alberta Innovates. ANR (France) is gratefully acknowledged for its financial support of this work (ANR-15-CE09 0001-01).

Publisher Copyright:
© 2017 American Chemical Society.

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