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Structuration et Propriétés Electroniques de Matériaux pi-Conjugués Modèles Sondées à l'Echelle Moléculaire par Microscopie en Champ Proche

Abstract : The expected limits of silicon-based microelectronics in the coming years, have promoted the development of alternative solutions. Among them, organic electronics, using pi-conjugated organic materials as the active part of components, sounds very attractive. Increases observed the past 20 years in the performances of organic devices, find for a great part their origin in a better structure of the active film and the understanding of the relationship between structure and electronic properties in these materials still appears as a keynote for organic electronics.
An STM structural study of self-assembled monolayers of either small molecules synthesised at the laboratory or polythiophenes was carried out in a first time to bring out self-assembly mechanisms. For the polymer monolayers, crystalline properties could be considerably improved with annealing of the sample. An organised second layer was observed for the first time on sample with higher coverage.
Finally the influence of local inter or intra-chain conformation on polymer electronic properties was investigated by two-dimensional scanning tunnelling spectroscopy. Although the electronic structure of the polymer seems unaffected by intra-chain defect such as folds, an increase of the bandgap was observed above isolated chains of the second layer. This is rather surprising as such chains are generally assumed to be pi-stacked on the first layer, which should cause a partial closure of the bandgap.
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https://tel.archives-ouvertes.fr/tel-00196927
Contributor : Lorette Scifo <>
Submitted on : Thursday, December 13, 2007 - 6:44:00 PM
Last modification on : Wednesday, November 4, 2020 - 2:33:35 PM
Long-term archiving on: : Monday, April 12, 2010 - 7:26:34 AM

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  • HAL Id : tel-00196927, version 1

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Lorette Scifo. Structuration et Propriétés Electroniques de Matériaux pi-Conjugués Modèles Sondées à l'Echelle Moléculaire par Microscopie en Champ Proche. Physique [physics]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00196927⟩

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