Energy-Level Alignment for Single-Molecule Conductance of Extended Metal-Atom Chains
Journal
Angewandte Chemie
Journal Volume
127
Journal Issue
52
Pages
15960--15964
Date Issued
2015-11
Author(s)
Ta-Cheng Ting
Liang-Yan Hsu
Min-Jie Huang
Er-Chien Horng
Hao-Cheng Lu
Chan-Hsiang Hsu
Ching-Hong Jiang
Shie-Ming Peng
Chun-hsien Chen
Abstract
Abstract The use of single‐molecule junctions for various functions constitutes a central goal of molecular electronics. The functional features and the efficiency of electron transport are dictated by the degree of energy‐level alignment (ELA), that is, the offset potential between the electrode Fermi level and the frontier molecular orbitals. Examples manifesting ELA are rare owing to experimental challenges and the large energy barriers of typical model compounds. In this work, single‐molecule junctions of organometallic compounds with five metal centers joined in a collinear fashion were analyzed. The single‐molecule i – V scans could be conducted in a reliable manner, and the E FMO levels were electrochemically accessible. When the electrode Fermi level ( E F ) is close to the frontier orbitals ( E FMO ) of the bridging molecule, larger conductance was observed. The smaller | E F − E FMO | gap was also derived quantitatively, unambiguously confirming the ELA. The mechanism is described in terms of a two‐level model involving co‐tunneling and sequential tunneling processes.
SDGs
Type
journal article