Analyse des améliorations des propriétés électroniques des matériaux carbonés par interaction d'espèces chimiques : Approche numérique combinée à la spectroscopie Raman

Abstract : To analyze the improvements in electronic properties of carbon-based materials, an approach based on the density functional theory supported by Raman spectroscopy was used. The heart of this work is the study of doping in order to open up new paths for the design of innovative materials from nanodevices. These new structures are fibers whose the main component is a carbon nanotube or nanocarbon loaded polymers with molecules, optimizing electrical conduction. A brief introduction is presented on non-covalent species, leading to the best results reported in the literature, namely potassium, iodine and super acids. The graphite intercalation compounds by potassium atoms are analyzed first. The large charge transfer of the alkali directly influences the optical properties of graphene, resulting in a unique Raman signature with a shape change when the excitation energy is twice the shift of the Fermi level due to doping. Then, an exhaustive theoretical study of iodine doping is performed on a monolayer of graphene. Analysis of thermodynamic properties shows that a gradual increase in the recovery rate of the molecules, initially generates a phase transition of iodine adsorption mode, and ends with the formation of polyiodide complexes. These complexes, via a strong electron transfer, lead to the increase of the density of states at the Fermi level. This study is extended to carbon nanotubes, where a very large charge transfer is obtained after interacting either with chlorosulfonic acid molecules by redox reaction, or with iodine molecules. When there is a flow of a large electric current in these fibers, the Joule effect produces a desorption of dopants and reduces the electrical conductivity. This phenomenon is explained by the available number of conduction channels deducted from combined Raman signatures and electronic transport calculations. The local and average temperatures are extracted from Raman and transport data respectively. This work constitutes a coherent set of results as a basis for improving the transport properties.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01496541
Contributor : Abes Star <>
Submitted on : Monday, March 27, 2017 - 4:05:10 PM
Last modification on : Monday, April 29, 2019 - 4:01:28 PM
Long-term archiving on : Wednesday, June 28, 2017 - 3:01:27 PM

File

2016DamienTristant.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01496541, version 1

Citation

Damien Tristant. Analyse des améliorations des propriétés électroniques des matériaux carbonés par interaction d'espèces chimiques : Approche numérique combinée à la spectroscopie Raman. Chimie-Physique [physics.chem-ph]. INSA de Toulouse, 2016. Français. ⟨NNT : 2016ISAT0005⟩. ⟨tel-01496541⟩

Share

Metrics

Record views

981

Files downloads

496