Thiophene Derivatives on Gold and Molecular Dissociation Processes

Abstract

We report a systematic study of thiophene derivatives on gold surfaces. These molecules are of interest in molecular electronics, and the characracteristics of the thiophene–electrode interface in devices needs to be understood as it affects electron transport characteristics. Some experiments indicated S–C bond scission in contact with metals resulting in disruption of the π-electron system that affects charge transport, which would also be affected by presence of split-off chemisorbed sulfur. We explored this dissociation aspect by photoemission for the case of monocrystalline Au(111) surfaces and Au films grown on mica for a series of polythiophenes molecules (nT, n = 1–4, 6) as well as for α,ω-diquaterthiophene (DH4T) and dihexylsexithiophene (DH6T). The S 2p X-ray photoelectron spectroscopy peaks are found to have complex line shapes corresponding to S atoms with different core level binding energies (CLBE). Density functional theory calculations of adsorption energies and CLBEs were performed for va...