Electronic conductance and thermopower of single-molecule junctions of oligo(phenyleneethynylene) derivatives

Hervé Dekkiche (1) , Andrea Gemma (2) , Fatemeh Tabatabaei (3) , Andrei Batsanov (1) , Thomas Niehaus (3) , Bernd Gotsmann (2) , Martin Bryce (1)

1 Department of Chemistry [Durham, UK]
2 IBM Research [Zurich]
3 iLM - MMCI - iLM - Modélisation de la matière condensée et des interfaces

We report the synthesis and the single-molecule transport properties of three new oligo(phenyleneethynylene) (OPE3) derivatives possessing terminal dihydrobenzo[b]thiophene (DHBT) anchoring groups and various core substituents (phenylene, 2,5-dimethoxyphenylene and 9,10-anthracenyl). Their electronic conductance and their Seebeck coefficient have been determined using scanning tunneling microscopy-based break junction (STM-BJ) experiments between gold electrodes. The transport properties of the molecular junctions have been modelled using DFT-based computational methods which reveal a specific binding of the sulfur atom of the DHBT anchor to the electrodes. The experimentally determined Seebeck coefficient varies between −7.9 and −11.4 μV K⁻¹ in the series and the negative sign is consistent with charge transport through the LUMO levels of the molecules.

Domaines: Chimie organique

Hervé Dekkiche, Andrea Gemma, Fatemeh Tabatabaei, Andrei Batsanov, Thomas Niehaus, et al.. Electronic conductance and thermopower of single-molecule junctions of oligo(phenyleneethynylene) derivatives. Nanoscale, 2020, 12 (36), pp.18908-18917. ⟨10.1039/D0NR04413J⟩. ⟨hal-03193693⟩