Planar electronic devices represent an attractive approach towards roll-to-roll printed electronics without the need for the sequential, precisely aligned, patterning steps inherent in the fabrication of conventional ‘3D’ electronic devices. Self-switching diodes (SSDs) and in-plane-gate field-effect transistors (IPG-FETs) can be patterned using a single process into a substrate precoated with semiconductor.These devices function in depletion mode, requiring the semiconductor to be doped in order for the devices to function. To achieve this, a reliable and controllable method was developed for doping organic semiconducting polymers by the immersion of optimally deposited films in a solution of dopant. The process was shown to apply both semicrystalline and air-stable, amorphous materials indicating that the approach is broadly applicable to a wide range of organic semiconductors.Simultaneously with the development of the doping protocol specialised hot-embossing equipment was designed and constructed and a high-yielding method of patterning the structures of IPG-FETs and SSDs was arrived at. This method allowed for consistent and reliable patterning of features with a minimum line-width of 200nm.Following the development of these doping and patterning processes these were combined to fabricate controllably doped, functioning planar devices. SSDs showed true zero-threshold rectification behaviour with no observed breakdown in the reverse direction up to 100 V. IPG-FETs showed switching behaviour in response to an applied gate potential and were largely free of detectable gate leakage current, verifying the quality of the patterning process.Furthermore, high-performance semiconducting polymer PAAD was synthesised and characterised in field-effect transistors as steps towards its use in planar electronic devices. It was also shown that this material could be doped using the developed immersion doping protocol and that this protocol was compatible with top-gated device architectures and the use of fluoropolymer CYTOP as a dielectric.

Organic electronics based on π-conjugated semi-conductor raises new technology, such as organic film transistors, e-paper, and organic photovoltaic cells that can be implemented cost-effectively on large-area applications. Currently, the device performance is limited by low charge carrier mobility. Poly(3-hexylthiophene) (P3HT) and organic field effect transistors (OFET) is used as a model to investigate morphology of the organic film and corresponding electronic properties. In this thesis, processing parameters such as boiling points and solubility are controlled to impact the micro- and macro-morphology of the film to enhance the charge transport of the device. Alternative approach to improve ordering of polymer chains and increase in charge transport without post-treatment of P3HT solution is studied. The addition of high boiling good solvent to the relatively low boiling main solvent forms ordered packing of π-conjugated polymers during the deposition process. We show that addition of 1% of dichlorobenzene (DCB) to the chloroform based P3HT solution was sufficient to improve wetting and molecular structures of the film to increase carrier mobility. Systematic study of solvent-assisted re-annealing technique, which has potential application in OFET encapsulation and fabrication of top-contact OFET, is conducted to improve mobility of OFET, and, to suggest a cost-effective processing condition suitable for industrial application. Three process parameters: boiling point, polarity, and solubility are investigated to further understand the trend of film response to the solvent-assisted technique. We report the high boiling non-polar solvents with relatively high RED values promote highest improvement in molecular packing and formulate crystalline structure of the thin film, which increases the device performance.

This thesis deals with the synthesis of electroactiveorganic compounds. The synthesis of ethylenedioxy-benzodioxinstri-dioxin and tetra-dioxin are described. These molecules wereprepared with the aim of creating donor molecules for cationicradical salts. The symmetric analogs of tri-dioxin,methylenedioxy-derivative and ethylenedioxy-naphthalene werealso synthesized. Three different cation radical salts with 2:1stoichiometries were obtained from tri-dioxin, whiletetra-dioxin merely provided polycrystalline materials.Tri-dioxin and tetra-dioxin were also successful as operationalmatrixes in PALDI-TOF. Tetrathiafulvalenes with the2-dialkyl-amino-1,3-dithiolium-4-thiolate mesoion asbuilding-block was also synthesized. A series of doublyalkylthiol-substituted TTFs were prepared with the aim offorming self-assembly monolayers on gold surfaces in theapplication of organic thin film field-effect transistors.Film-formation for two TTFs were studied and they providedrelatively dense packed monolayers with a discrete distance ofthe TTF moiety from the gold surface. The mesoionic compound was also for the first time used inanumpolungreaction. The electrophile obtained in situ bytreatment of mesoion with sulfuryl chloride was reacted with avariety of electron-rich aromatic compounds. From the receivedproducts three new arylthio-substituted TTFs weresynthesized. <b>Keywords:</b>Synthesis, Benzodioxin, Tetrathiafulvalene,Mesoion, Organic Conductor, Cation Radical Salt, CyclicVoltammetry, Electrocrystallization, Self-Assembly Monolayer,SAM, Organic Field-Effect Transistor, OFET

<p>This thesis deals with the synthesis of electroactiveorganic compounds. The synthesis of ethylenedioxy-benzodioxinstri-dioxin and tetra-dioxin are described. These molecules wereprepared with the aim of creating donor molecules for cationicradical salts. The symmetric analogs of tri-dioxin,methylenedioxy-derivative and ethylenedioxy-naphthalene werealso synthesized. Three different cation radical salts with 2:1stoichiometries were obtained from tri-dioxin, whiletetra-dioxin merely provided polycrystalline materials.Tri-dioxin and tetra-dioxin were also successful as operationalmatrixes in PALDI-TOF.</p><p>Tetrathiafulvalenes with the2-dialkyl-amino-1,3-dithiolium-4-thiolate mesoion asbuilding-block was also synthesized. A series of doublyalkylthiol-substituted TTFs were prepared with the aim offorming self-assembly monolayers on gold surfaces in theapplication of organic thin film field-effect transistors.Film-formation for two TTFs were studied and they providedrelatively dense packed monolayers with a discrete distance ofthe TTF moiety from the gold surface.</p><p>The mesoionic compound was also for the first time used inan<i>umpolung</i>reaction. The electrophile obtained in situ bytreatment of mesoion with sulfuryl chloride was reacted with avariety of electron-rich aromatic compounds. From the receivedproducts three new arylthio-substituted TTFs weresynthesized.</p><p><b>Keywords:</b>Synthesis, Benzodioxin, Tetrathiafulvalene,Mesoion, Organic Conductor, Cation Radical Salt, CyclicVoltammetry, Electrocrystallization, Self-Assembly Monolayer,SAM, Organic Field-Effect Transistor, OFET</p>

Cette thèse porte sur l'étude d'un diélectrique de type ferroélectrique pour une application aux transistors organiques. La configuration adoptée est de type bottom-gate top- contact. Le matériau semi-conducteur utilisé est un transporteur d'électrons. Dans la première partie de ce projet, nous avons réalisé des transistors organiques à effet de champ (OFETs) avec une couche de PMMA comme diélectrique de grille. Ce matériau, très étudié et connu, permet d'avoir un composant servant de référence. Nous avons également mené une étude sur la longueur de canal, la vitesse de dépôt du semi-conducteur organique et l'épaisseur du diélectrique, en vue d'en déduire l'influence de ces grandeurs sur les performances électriques des OFETs. Après l'optimisation de ces paramètres, nous avons démontré une amélioration de la mobilité des porteurs, une augmentation du rapport Ion/Ioff, une amélioration de la capacité et une diminution des tensions d'alimentation et de seuil. Ces résultats ont été interprétés à l'aide de caractérisations électriques. Dans un second temps, le diélectrique ferroélectrique poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) a été ajouté au composant, afin de réaliser un diélectrique hybride avec le PMMA. Ce dernier permet de combiner les avantages de la haute permittivité relative du P(VDF-TrFE), et de la faible rugosité du film de PMMA en contact avec le semiconducteur. Une étude comparative a été effectuée avec les transistors de référence. Il en ressort, pour une épaisseur identique de diélectrique, une diminution des tensions d'alimentation et de seuil, et une amélioration de la mobilité des charges avec l'OFET implémentant le matériau ferroélectrique. La discussion de ces résultats est appuyée par des caractérisations électriques et morphologiques. / This thesis deals with the study of a ferroelectric material as gate dielectric for organic transistor applications. The configuration adopted is bottom-gate top-contact. The semiconductor used is an electron transport material. In a first part, we made organic field effect transistors (OFETs) with a layer of PMMA as a gate dielectric. This material, very studied and well known, serves as reference. We also carried out a study on the channel length, the organic semiconductor deposition rate and the dielectric thickness, in order to deduce the impact of these parameters on OFETs performances. After optimization, we have demonstrated an improvement of the mobility, on/off current ratio, capacitance and a reduction of supply and threshold voltages. These results have been interpreted using electrical characterizations. In a second step, the poly (vinylidenefluoride-co- trifluoroethylene) (P(VDF-TrFE)) ferroelectric material was added to provide a hybrid dielectric with PMMA. This OFET combine the advantages of high permittivity of P(VDF-TrFE) and low roughness of PMMA. A comparative study was carried out with reference transistors. For same dielectric thickness, a reduction of the supply and threshold voltages and an improvement of the mobility is obtained for the OFET implementing ferroelectric material. The discussion of these results is supported by electrical and morphological characterizations.

Les travaux effectués dans le cadre de la thèse de doctorat, ont porté sur la mesure de la mobilité des porteurs de charge dans des semi-conducteurs organiques. La thèse de doctorat a été réalisée en "cotutelle" dans le cadre du programme franco-polonais entre le Département de Chimie de l'Université de Technologie de Wroclaw et les Laboratoire de Chimie des Polymères de l'Université Pierre et Marie Curie, Paris. Certains des résultats présentés ont été obtenus dans le cadre d'un stage scientifique dans la groupe du prof. Jeong Weon Wu à l'Ewha Womans University, Séoul, Corée du Sud. Cette thèse se compose de deux parties principales, une théoriques et expérimentales. Dans le premier, je décris matériaux semi-conducteurs organiques et les techniques de mesure, que je utilisé au cours de la thèse. La partie expérimentale est composé de cinq chapitres. En raison du fait que les molécules recherchées diffèrent fortement dans leurs structures et leurs propriétés, je décidai de présenter chaque chapitre dans la forme d'un article scientifique. La caractéristique commune de toutes les molécules étudiées est la possibilité de l'auto-organisation supramoléculaire dans les structures de cristaux liquides. Je étudié composés accepteurs-donneurs, qui peut être comprise comme matériaux de type p et n semi-conducteur. Au cours de ma thèse j'ai utilisé la technique de temps de vol et mesuré les caractéristiques courant-tension de transistor à effet de champ organique pour déterminer la mobilité des porteurs des charges dans semi-conducteurs organiques. Enfin, je payé beaucoup d'attention aux techniques spectroscopiques, y compris d'absorption femtoseconde résolue en temps. / I have carried out my PhD Thesis within the framework of a Polish-French “cotutelle” program, between Chemistry Department of Wroclaw University of Technology and Laboratoire de Chimie des Polymères of Université Pierre et Marie Curie. The Polish advisor of this work was Prof. Marek Samoć and the French advisor was Prof. André Jean Attias. A part of results described in this Thesis was obtained during a research internship in a group of Prof. Jeong Weon Wu from Ewha Womans University in South Korea. This Thesis is composed of two main parts, a theoretical and experimental. In the former I describe organic semiconducting materials and the measurement techniques, which I utilized during the PhD work. The experimental part is composed of five chapters. Due to the fact that the investigated molecules differed strongly in their structures and properties, I decided to present every chapter within a form of a scientific article. The common feature of all explored molecules is the possibility of supramolecular self organization into liquid crystalline structures, and the opportunity of utilizing these materials in organic electronics and optoelectronics. Among these molecules, both oligomers and polymers can be distinguished. I studied also donor acceptor compounds, which in terms of organic electronics can be understood as materials with p and n type semiconducting character. During my PhD Thesis I used Time-of-Flight technique and measured current voltage characteristics of organic field effect transistor (OFET) to determine charge carriers mobility in organic semiconductor. Finally, I paid a lot of attention to the spectroscopic techniques, including fs transient absorption.

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Two major projects involving the use of solution processed blended semiconductors for organic field effect transistors (OFET) were explored. The first incorporated unsorted single walled carbon nanotubes (SWCNTs) into a diketopyrrolopyrrole-quarterthiophene (DPP-QT) semiconductor to enhance the mobility of the OFET. 2 wt % SWCNT was found to be the optimal blend ratio, nearly doubling the device mobility (0.6 to 0.98 cm^2/V·s). Beyond this ratio, the metallic content of the SWCNT’s dropped the on/off ratio below acceptable levels. When source drain metals who’s work function poorly matched that of the DPP-QT semiconductors highest occupied molecular orbital (HOMO) were used, the SWCNT could dramatically reduce the charge injection ratio with best results achieved for Al, dropping the contact resistance from 10^5 to 45 MΩ. The second project explored the addition of small molecule additives into a UV-sensitive semiconductor 2,7-dipentyl[1]benzothieno[3,2-b][1] benzothiophene (C5-BTBT) mixed with a polymethyl methacrylate (PMMA) polymer binder. We generated a C5-BTBT based phototransistor sensitive to UV-A light. The HOMO and lowest unoccupied molecular orbital (LUMO) of C5-BTBT and the various additives were measured and discovered to play a critical role in how the device operates. We discovered if an additive has a LUMO lower in energy than C5-BTBT, it can act as a charge trap for a photogenerated electron. Electron deficient additives were found to retain a trapped electron for an extended period of time, allowing the device to remain in a high current state for an extended period of time (>1 hour). This provides an opportunity for the device to be used as an optical memory system or photoswitch. The best system could detect UV-A with a Pill > 10^5 and a photoresponsivity of 40 A/W at a Pinc of 0.0427 mW/cm^2. / Thesis / Doctor of Philosophy (PhD) / An emerging field of electronics is the use of organic materials that can be solution processed, to reduce manufacturing costs and make new and interesting products. Here we used unsorted carbon nanotubes blended into the semiconductor layer of a transistor, providing a bridge for the energy mismatch between the electrodes and the semiconductor. This allowed us the freedom to choose different metals to act as our electrodes when making electronic devices. Additionally through the correct choice of semiconductor, we added device functionality, making it responsive to UV-A light. This produced a device that could act as a UV-A sensor, logic switch or memory device. These devices are air stable and solution processable, a necessity if they are to be used in real world applications.

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