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 journalArticle

23 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

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