12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Adverse effects of asymmetric contacts on singl...
View graph of relations

« Back

Adverse effects of asymmetric contacts on single molecule conductances of HS(CH2)(n) COOH in nanoelectrical junctions

Research output: Contribution to journalJournal article

Published

Article number125203
Journal publication date25/03/2009
JournalNanotechnology
Journal number12
Volume20
Number of pages9
Pages-
Original languageEnglish

Abstract

A scanning tunnelling microscope has been used to determine the conductance of single molecular wires with the configuration X-bridge - X, X-bridge-Y and Y-bridge-Y (X = thiol terminus and Y = COOH). We find that for molecular wires with mixed functional groups (X - bridge - Y) the single molecule conductance decreases with respect to the comparable symmetric molecules. These differences are confirmed by theoretical computations based on a combination of density functional theory and the non-equilibrium Green's functions formalism. This study demonstrates that the apparent contact resistance, as well as being highly sensitive to the type of the anchoring group, is also strongly influenced by contact-asymmetry of the single molecular junction which in this case decreases the transmission. This highlights that contact-asymmetry is a significant factor to be considered when evaluating nanoelectrical junctions incorporating single molecules.