Fonctionnalisation du distyryl-bithiophène (impact sur la structure moléculaire sur les performances électriques des transistors à effet de champ)

La recherche de nouveaux semi-conducteurs organiques de type p et n stables à l air, pour la réalisation de transistors à base de couche mince organique (OTFTs), demeure un enjeu majeure pour le développement de l électronique organique. Récemment, il a été montré au laboratoire que les distyryl-oligothiophènes constituent une nouvelle classe de semi-conducteurs organiques de type p qui conduisent à des OTFTs présentant de très bonnes mobilités des porteurs de charge associées à une stabilité exceptionnelle des performances électriques à l air au cours du temps. Au cours de ce travail de thèse plusieurs voies de synthèse ont été développées afin de fonctionnaliser le distyryl-bithiophène (DS2T) avec différents groupements fonctionnels dans le but d évaluer leurs impacts sur les propriétés électriques des OTFTs. Après, un premier chapitre qui rappelle brièvement l enjeu économique lié au développement des transistors basés sur les semi-conducteurs organiques et les différents points clés à résoudre, le second chapitre est consacré à la fonctionnalisation du DS2T par des groupements électro-attracteurs du type perfluoroalkyle ou cyano afin d obtenir des semi-conducteurs de type n. Contrairement à ce qui était attendu, le comportement en film mince révèle un caractère soit isolant soit de type p. Outre les résultats expérimentaux, une étude en Density Functional Theory (DFT) visant à mieux comprendre les effets de ces groupements sur le DS2T est décrite. Au cours de la troisième partie, le DS2T a été fonctionnalisé aux extrémités par des chaînes hexyles pour permettre la fabrication des OTFTs par la voie liquide. Les processus de fabrication décrits offrent l avantage d être peu onéreux, tout en tirant parti des propriétés de cristal liquide pour une organisation moléculaire optimale dans la phase solide. Les performances des OTFTs préparés à la tournette, par dépôt par goutte et par jet de matière sont décrites et comparées à celles obtenues pour un OTFT préparé par évaporation sous vide. Enfin au cours de la dernière partie, une stratégie de synthèse a été développée pour rigidifier le coeur bithiophène dans le but d accroître la planéité du semi-conducteur et donc d améliorer l empilement de type p dans la phase solide. Tout ceci affin d accroitre les performances électriques des OTFTs. La structure RX du composé ponté (kite-DS2T) révèle une forme concave totalement inattendue dans la série oligothiophène. Malgré cette forme, a priori pénalisante, une amélioration par un facteur 5 de la mobilité de type p a été obtenue par comparaison au DS2T. Enfin, au cours de la dernière partie de ce chapitre, une première tentative de transformation au niveau moléculaire de ce nouveau semi-conducteur est décrite pour passer d un système de type p à un système de type nThe research of new air stable p- and n-type organic semiconductors that are the basis of organic thin film transistors (OTFTs) are of key interest in the development of improved organic electronics. Recently, our research group has reported on distyryl-oligothiophenes as a novel class of p-type organic semiconductors with high mobilities and an exceptional stability of electrical performances in air over time. During work done for this dissertation, different synthetic routes were developed in order to functionalize the distyryl-bithiophene (DS2T) with different functional groups to evaluate the impact of chemical substitutions on electronic properties in OTFT devices. The first introductory chapter is dedicated to a short overview of the economic challenges in the development of OTFTs and the different key issues that need to be addressed. The second chapter is devoted to the functionalization of DS2T with different electron-withdrawing groups (EWGs) as perfluoroalkyl chains or cyano groups to obtain n-type semiconductors. Contrary to what has been expected, thin films based on such molecules act as insulating layers or p-type channels. In addition to experimental results, a study by Density Functional Theory (DFT) is described in order to evaluate the effects of such EWGs in DS2T. The third chapter explains how DS2T was end-substituted by two alkyl chains for the fabrication of OTFTs by the solution phase. The described process offers reduced costs with the great advantage of liquid crystalline properties needed for an optimum molecular organization in the solid phase. The performances of OTFTs prepared by spin-coating, drop-casting and by ink-jet are described and compared to those obtained with OTFTs prepared by vacuum evaporation. Finally, a new synthetic route was developed to rigidify the bithiophene core in order to increase the planarity of the semiconducting molecule and as a consequence to increase the p-stacking in the solid phase. The main purpose of the strategy was to increase the OTFT performances. The X-Ray structure of the bridged compound (kite-DS2T) revealed a concave structure unexpected in the oligothiophene series. Despite this molecular structure, unfavourable as a first instance, an increase by a factor 5 in the p-type mobility is obtained for kite-DS2T as compared to DS2T. At the end of this chapter a chemical modification of the new kite-DS2T is described as a first alternative to switch the system from p-type to n-type.AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Effect of template ion–ligand complex stoichiometry on selectivity of ion-imprinted polymers

International audienceIn order to highlight the importance of the complex stoichiometry during ion imprinted polymer (IIP) synthesis, we investigated the effect of the complex structure on IIPs selectivity by adjusting the complex stoichiometry before polymerization. 2-(aminomethyl)pyridine monomer (amp) was chosen as a functionalized ligand for nickel(II) ions and a polymerizable vinylbenzyl derivative (Vbamp) was prepared. Complex formation was studied by varying the nickel/Vbamp ratio and recording absorption spectra of the complexes at the polymerization conditions. Using a least-squares minimization scheme, the complex species distribution was successfully established. From these results, it was possible to choose the metal/ligand stoichiometry in the complex (1:1; 1:2 or 1:3) by adjusting the initial metal/ligand ratio. IIPs were then prepared by inverse suspension copolymerization of Vbamp with ethyleneglycol dimethacrylate (EDMA). Highly porous particles with good nickel binding capacity and good Ni/Zn selectivity even at acidic conditions were obtained. Equilibrium uptake of Ni(II) at pH 7 ranged from 0.12 to 0.2 mmol g−1 and relative selective coefficient was as high as 260 for the IIP prepared using the Ni(Vbamp)2 complex

Dibutylamino end-capped benzo[2,1-b:3,4-b′]dithiophene-4,5-dione and benzo[2,1-b:3,4-b′]dithiophene versus non modified analogues: contribution of amino groups

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Synthesis and first characterization of N-alkyldiaminoresorcinols

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Organic Thin Film Transistors Based on Distyryl-Oligothiophenes: Role of AFM Images in Analyses of Charge Transport Properties

Significant advances have been made recently in the area of organic electronics and optoelectronics based on small molecules as a result of an improved chemistry and a better technology. Together with light emitting diodes and solar cells, transistors are among the most studied components. The development of new semiconductors induced a real improvement in organic thin film transistor’s performances. Additionally, the synthesis of new soluble and air-stable molecules with the ability to process the active materials at low temperatures over large areas on substrates such as plastic or paper provide unique technologies and generate new applications. However the control of the solid state structure has emerged as essential to realize the full intrinsic potential that organic semiconductors possess. Atomic force microscopy (AFM) was likely to contribute to a further advancement of knowledge. The ability of the AFM to produce three dimensional maps at the micro- and nanometer scale has greatly increased its popularity as an imaging tool. Recently, distyryl-oligothiophenes and their derivatives appear as a new class of molecular semiconductors. Detailed morphological studies of organic active layers based on such new semiconductors involved in organic thin film transistors (OTFTs) have brought a large knowledge about the impact of chemical and physico-chemical aspects on charge transport efficiency

Control of the optical properties upon a reversible [2+2] cycloaddition of 3-(4-N,N-dibutylamino)-styryl)-3’-(dicyanovinyl)-bithiophene

International audienceIn the course of our studies of D-π-A push-pull chromophores we have envisioned the design of the novel 3-(4-N,N-dibutylamino)-styryl)-3’-(dicyanovinyl)-bithiophene derivative as a potential building block for optoelectronic applications. However, during the synthesis of this chromophore, a cycloadduct compound confirmed by X-ray structure was obtained by an intramolecular [2 + 2] cycloaddition reaction. The retro cycloaddition reaction carried out in thermal conditions and followed by UV–Visible absorption spectrophotometry afforded quantitively the target chromophore. Electrochemical properties recorded are in good agreement with open and close compounds. Mechanism involves cis/trans isomerization was proposed to explain the complete conversio

Proquinoid acceptors as building blocks for the design of efficient π-conjugated fluorophores with high electron affinity

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