| Autor: |
Ivie JA; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States., Bamberger ND; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States., Parida KN; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States., Shepard S; Department of Physics, Binghamton University-SUNY, 4400 Vestal Parkway East, Binghamton, New York 13902, United States., Dyer D; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States., Saraiva-Souza A; Departamento de Física, Universidade Federal do Maranhão, São Luís, Massachusetts 65080-805, Brazil., Himmelhuber R; College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721, United States., McGrath DV; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States., Smeu M; Department of Physics, Binghamton University-SUNY, 4400 Vestal Parkway East, Binghamton, New York 13902, United States., Monti OLA; Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States.; Department of Physics, University of Arizona, 1118 E. Fourth Street, Tucson, Arizona 85721, United States. |
| Abstrakt: |
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. |
