Electrical Resistance of Long Oligothiophene Molecules

Abstract

The electrical resistance of single oligothiophene molecular wires with lengths ranging from 2.2 nm (5-mer) to 9 nm (23-mer) was measured by the break junction method. A linear relationship between the molecular length and resistance was found for molecules longer than 11mer, whereas an exponential increase in the resistance was observed for molecules shorter than 11-mer. These results indicate that the carrier transport mechanism changes from tunneling to hopping at around 11-14-mer (5.6 nm).

Electrical Conductance of Single Oligothiophene Molecular Wires: Temperature Effect

“…We have previously reported the change of the scaling law by using oligothiophene molecular wires with the lengths ranging from 2 nm to 9 nm [8,9]. Similar results were also reported by other groups [10][11][12].…”

Electrical characteristics of conjugated self-assembled monolayers in large-area molecular junctions

“…2 Studies on various -conjugated molecules have been performed. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The molecules, with delocalized electrons due to sp 2 hybridized carbon atoms, exhibit a smaller energy gap between the highest occupied molecular orbital ͑HOMO͒ and the lowest unoccupied molecular orbital ͑LUMO͒. For -conjugated molecules longer than ϳ3 nm hopping conduction was observed.…”

Oligo(aryleneethynylene)s with Terminal Pyridyl Groups: Synthesis and Length Dependence of the Tunneling-to-Hopping Transition of Single-Molecule Conductances

“…4 nm for thiol-anchored oligophenyleneimines. 25 Singlemolecule conductance experiments employing the STM-BJ techniques reported characteristic transition lengths of 5.6 to 6.8 nm for polythiophenes 55 and 5.2 to 7.3 nm for oligofluorene-based molecular wires, 26 both terminated with thiol anchors. We note that for the oligofluorene series the experiments are very limited within the length range investigated.…”