Abstract
We employ a one-electron, tight-binding model of an electrode-molecule- electrode junction to explore the fundamental relationship between adsorption geometry and electron transport, producing exact results (within this model). By varying the chemisorption location (e.g., atop a surface atom or in a hollow site between surface atoms) and the molecule-electrode coupling, we find that the largest currents are realized when the molecule (i) is highly coordinated by the surface and (ii) has favorable overlap with electrode states near the Fermi level. We also show the importance of electrode-induced molecular level shifting for certain adsorption geometries, which can cause molecular levels far from the Fermi level to conduct better than those near the Fermi level. Since all of these factors are greatly influenced by the chemical moiety used to link the molecule to an electrode, these results present a set of guidelines to help choose alligator clips for molecular electronic devices.
| Original language | English (US) |
|---|---|
| Article number | 154708 |
| Journal | Journal of Chemical Physics |
| Volume | 134 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 21 2011 |
Funding
We are grateful to Gemma C. Solomon and Shane M. Parker for helpful suggestions. M.G.R. thanks the (U.S.) Department of Energy (DOE) Computational Science Graduate Fellowship Program (Grant No. DE-FG02-97ER25308) for a graduate fellowship. This work was partially supported by the (U.S.) National Science Foundation (NSF) (Grant Nos. CHE-1012207 and CHE-0719420), the MRSEC program of the National Science Foundation (NSF) (DMR-0520513), and the Nonequilibrium Energy Research Center (NERC), which is an Energy Frontier Research Center funded by the (U.S.) Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0000989.
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry