13.07.2015 Views

Etudes de cristaux liquides colonnaires en solution organique et en ...

Etudes de cristaux liquides colonnaires en solution organique et en ...

Etudes de cristaux liquides colonnaires en solution organique et en ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

<strong>Etu<strong>de</strong>s</strong> <strong>de</strong> <strong>cristaux</strong> liqui<strong>de</strong>s <strong>colonnaires</strong> <strong>en</strong> <strong>solution</strong> <strong>organique</strong> <strong>et</strong> <strong>en</strong> film minceouvertRésumé : Les travaux effectués dans c<strong>et</strong>te thèse concern<strong>en</strong>t les cellules photovoltaïquesfabriquées à partir <strong>de</strong> matériaux <strong>organique</strong>s discotiques. Ces <strong>de</strong>rniers possè<strong>de</strong>nt <strong>de</strong> bonnespropriétés <strong>de</strong> transport <strong>de</strong> charges <strong>et</strong> d’excitons lorsque les matériaux impliqués sont ordonnéssous forme <strong>de</strong> colonnes. Une stratégie est proposée <strong>et</strong> étudiée pour améliorer les paramètres <strong>de</strong>ces dispositifs <strong>organique</strong>s. En particulier, <strong>de</strong>s investigations ont été m<strong>en</strong>és sur la structuration<strong>de</strong>s matériaux <strong>en</strong> <strong>solution</strong> <strong>et</strong> <strong>en</strong> films minces. En divers solvants <strong>organique</strong>s, l’agrégation <strong>de</strong>smolécules discotiques <strong>en</strong> colonnes d’une taille <strong>de</strong> quelques nanomètres a été mis <strong>en</strong> évi<strong>de</strong>nce,avec un empilem<strong>en</strong>t <strong>de</strong>nse <strong>de</strong>s disques dans la colonne <strong>et</strong> sans ordre intercolonnaire dépassantles voisins directs. Par diffraction <strong>de</strong>s rayons X <strong>en</strong> inci<strong>de</strong>nce rasante, la structure <strong>de</strong>s filmsminces a été exploré. Les résultats soulign<strong>en</strong>t l’indisp<strong>en</strong>sable nécessité d’ori<strong>en</strong>ter les films <strong>de</strong><strong>cristaux</strong> liqui<strong>de</strong>s <strong>colonnaires</strong>.Columnar liquid crystals in organic <strong>solution</strong> and in thin op<strong>en</strong> filmsAbstract : The studies un<strong>de</strong>rtak<strong>en</strong> in this thesis are of relevance for solar cells ma<strong>de</strong> fromdiscotic organic materials. These cells offer good charge and exciton transport properties ifthe materials used are structured in columns. An approach is proposed and studied whichaims to optimise the param<strong>et</strong>ers of these organic <strong>de</strong>vices. In particular, the self-assemblyof the materials has be<strong>en</strong> studied in <strong>solution</strong> and in thin films. In various organic solv<strong>en</strong>ts,the aggregation of the discotic molecules into columns of a few nanom<strong>et</strong>res in size has be<strong>en</strong>observed, with <strong>de</strong>nse stacking of the discs within the columns and without intercolumnaror<strong>de</strong>r beyond next neighbours. By grazing inci<strong>de</strong>nce X-ray diffraction, the structure of thinfilms has be<strong>en</strong> elucidated. The results un<strong>de</strong>rline the unavoidable necessity to ori<strong>en</strong>tate thecolumnar liquid crystalline films.Mots-clés : <strong>cristaux</strong> liqui<strong>de</strong>s <strong>colonnaires</strong>, agrégation <strong>en</strong> <strong>solution</strong>, ancrages homéotrope<strong>et</strong> planaire, diffusion <strong>de</strong> la lumière, rayons X <strong>en</strong> inci<strong>de</strong>nce rasante

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!