Correlated energy-level alignment effects determine substituent-tuned single-molecule conductance

Jeffrey A. Ivie, Nathan D. Bamberger, Keshaba N. Parida, Stuart Shepard, Dylan Dyer, Aldilene Saraiva-Souza, Roland Himmelhuber, Dominic V. Mcgrath, Manuel Smeu, Oliver L.A. Monti

Research output: Contribution to journalArticlepeer-review

Abstract

The rational design of single-molecule electrical components requires a deep and predictive understanding of structure-function relationships. Here, we explore the relationship between chemical substituents and the conductance of metal-single-molecule-metal junctions, using functionalized oligophenylenevinylenes as a model system. Using a combination of mechanically controlled break-junction experiments and various levels of theory including non-equilibrium Green's functions, we demonstrate that the connection between gas-phase molecular electronic structure and in-junction molecular conductance is complicated by the involvement of multiple mutually correlated and opposing effects that contribute to energy-level alignment in the junction. We propose that these opposing correlations represent powerful new "design principles"because their physical origins make them broadly applicable, and they are capable of predicting the direction and relative magnitude of observed conductance trends. In particular, we show that they are consistent with the observed conductance variability not just within our own experimental results but also within disparate molecular series reported in the literature and, crucially, with the trend in variability across these molecular series, which previous simple models fail to explain. The design principles introduced here can therefore aid in both screening and suggesting novel design strategies for maximizing conductance tunability in single-molecule systems.

Original languageEnglish (US)
Pages (from-to)4267-4277
Number of pages11
JournalACS Applied Materials and Interfaces
Volume13
Issue number3
DOIs
StatePublished - Jan 27 2021

Keywords

  • Break-junction experiment
  • Density functional theory
  • Energy-level alignment
  • Image charge effect
  • Molecular electronics
  • Single-molecule conductance
  • Structure-function relationships
  • Vacuum level shift

ASJC Scopus subject areas

  • Materials Science(all)

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