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Cette thèse porte sur l’étude de la stabilité et de la fiabilité de transistors organiques imprimés au CEA-Liten. Des OTFTs de type P ont été fabriqués sur plastique, avec un polymère semi-conducteur (SCO) de type P (SP400 de Merck) et un fluoropolymère en tant que diélectrique. Tout d’abord, un protocole expérimental pour la caractérisation électrique a été mis en place afin de s’affranchir de potentiels effets dus à l’environnement, la mesure ou le vieillissement des OTFTs. Puis un modèle basé sur l’expression de la charge d’accumulation dans le transistor a été développé. Ce modèle a permis l’extraction des paramètres des OTFTs lors de mesures à basses températures, qui ont mis en évidence un transport de charges en température dans le SCO. Enfin, l’impact du stress électrique de grille négatif sur les caractéristiques des transistors a été étudié. La stabilité électrique des P-OTFTs a été mesurée sur plusieurs empilements afin d’étudier l’influence du diélectrique ou de sa méthode de dépôt et l’influence de la grille (électrode en encre argent imprimée ou en or pulvérisée). / This thesis project is about the study of stability and reliability of organic transistors printed at CEA-Liten. P-Type OTFTs were manufactured on plastic substrate, with a p-type polymer semiconductor (SP400 from Merck) and a fluoropolymer as dielectric. First, an experimental protocol for electrical characterization was determined in order to overcome potential effects due to environment, measurements or aging of OTFTs. Then a model based on the expression of the accumulation charge in the transistor was developed. This model allowed the OTFT parameters’ extraction during low temperature measurements, which showed a temperature-activated charges transport in the OSC. Finally, the impact of negative gate bias stress on OTFTs’ characteristics was studied. The electrical stability of the P-OTFTs was measured on several stacks to study the influence of the dielectric material or its deposition method and the influence of the gate (printed silver ink or sputtered gold electrode).

L'électronique plastique est devenue en une dizaine d'années un domaine actif, tant en recherche fondamentale qu'en application. La compréhension et le contrôle des forces motrices du transport ambipolaire est un objectif clé de la recherche dans le domaine de l'électronique organique, et plus particulièrement des transistors. Après une introduction rappelant les principes des transistors organiques ambipolaires et un état de l'art du domaine, les outils et méthodes utilisés au cours de ce travail ont été présentés. Le premier chapitre présente les résultats obtenus des transistors réalisés par évaporation sous vide de phtalocyanines de cuivre. Dans un premier temps la stabilité et les performances des deux semi-conducteurs isolés ont été caractérisés, puis une étude morphologique, électrique et structurelle a été menée sur des dispositifs en structure bicouche ou interpénétrée. Le deuxième chapitre présente une nouvelle méthode d'élaboration de transistors : le LIFT (LAser Induced Forward Transfer). Les premiers transistors à canal p et n'ont ainsi été réalisés à base de phtalocyanines de cuivre, avant de tenter d'obtenir des dispositifs ambipolaires. Cette méthode récente peut permettre de déposer des films à une très grande cadence menant à des dispositifs microstructurés de grande précision. Le dernier chapitre présente une approche par voie liquide. Des solutions de DH-DS2T et PDIF-CN2 ont été élaborées afin de réaliser des encres par le mélange de ces deux solutions pour être déposées par tournette ou dépôt par goutte. en conclusion, les différentes méthodes sont évaluées et comparées afin de déterminer leur utilité et applicabilité respectives. / During the past decade, plactic electronics has become an active research domain, both fundamental and application side. Undestanding and controling the phenomenom which rule the ambipolar transport is one of the main aims of research in organic electronics and transistors. After an introduction giving the principles and a state of the art of organic ambipolar transistors, materials and methods used are described. The first chapter deals with the results obtains whith transistors based on copper phtalocyanines elaborated by a vacuum evaporation process. Stability is isolated moieties was first investigated. Then, morphology, performance and structure of bilayer and blend systems. The second chapter presents the results obtained for transistors elabored by LIFT (Laser Induced Forward Transfer). The first n-channel and p-channel transistors elabored by laser deposition were obtained from copper phtalocynanines. Then the possibility to obtain ambipolar decives was investigated. This brand new technology can permit to create microstructures with a great deposition velocity. The last chapter presents the liquid way approach. DH-DS2T and PDIF-CN2 solutions were used to realise link by mixing the two solutions. those ink where deposited by drop-cast or spin-coating. Finally, the different methods used in this work were evaluated and compared in order to define their usefulness and applicability

I) Introduction p-Conjugated polymers inherently combine electronic properties of inorganic semiconductor crystals and material characteristics of organic plastics due to their special molecular design. This unique combination has led to developing new unconventional optoelectronic technologies and, further, resulted in the evolution of semiconducting polymers (SCPs) as fundamental components for novel electronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) and organic solar cells (OSCs).[1–5] Moreover, the material flexibility, capability for thin-film formation, and solution processibility additionally allow utilizing modern printing technologies for the large-scale fabrication of flexible, light-weight organic electronics. This especially enables to significantly increase the production speed and, moreover, to drastically reduce the costs per unit.[6, 7] In particular, transistors are the most important elements in modern functional electronic devices because of acting as electronic switches in logic circuits or in displays to control pixels. However, due to molecular arrangement and interactions, the electronic performance of SCPs cannot compete with the one of monocrystalline silicon which is used in state-of-the-art high-performance microtechnology.[5, 8] Nonetheless, intensive and continuing efforts of scientists focused on improving the performance of OFETs, with the special focus on the charge carrier mobility, by optimizing the polymer structure, processing conditions and OFET device architecture. By this, it was possible to identify crucial relationships between polymer structure, optoelectronic properties, microstructure, and OFET performance.[8] Nowadays, the interdisciplinary scientific success is represented by high-performance SCPs with charge carrier mobilities exceeding the value of amorphous silicon.[3, 9] However, further research is essential to enable developing the next generation of electronic devices for application in healthcare, safety technology, transportation, and communication. II) Objective and Results Within the scope of this doctoral thesis, current high-performance p-conjugated SCPs should be studied comprehensively to improve the present understanding about the interdependency between molecular structure, material properties and charge transport. Therefore, the extensive research approaches focused on different key aspects of high charge carrier mobility polymers for organic transistors. The performed investigations comprised the impact of, first, novel design concepts, second, precise structural modifications and, third, synthetic and processing conditions and led to the major findings listed below. 1. The design concept of tuning the p-conjugation length allows to gradually modulate physical material properties and demonstrates that a strong localization of frontier molecular orbitals in combination with a high degree of thin-film ordering can provide a favorable platform for charge transport in p-conjugated semiconducting polymers.[1] 2. The replacement of thiophene units with thiazoles in naphthalene diimide-based p- conjugated polymers allows to increase interchain interactions and to lower frontier molecular orbitals. This compensates the potentially detrimental enhancement of backbone torsion and drives the charge transport to unipolar electron transport, whereas mobility values are partially comparable with those of the respective thiophene containing analogs. 3. p-Conjugated diketopyrrolo[3,4-c]pyrrole-based copolymers can be synthesized within fifteen minutes what, in combination with avoiding aqueous washings and optimizing processing conditions, allowed an increase in morphological and energetic order and, thus, improved the charge transport properties significantly. III) Conclusion The key findings of this doctoral thesis provide new significant insights into important aspects of designing, synthesizing and processing high charge carrier mobility polymers. By this, they can guide future research to further improve the performance of organic electronic devices - decisive for driving the development and fabrication of smart, functional and wearable next-generation electronics. References [1] T. Erdmann, S. Fabiano, B. Milián-Medina, D. Hanifi, Z. Chen, M. Berggren, J. Gierschner, A. Salleo, A. Kiriy, B. Voit, A. Facchetti, Advanced Materials 2016, 28 (41), 9169–9174, DOI:10.1002/adma.201602923. [2] Y. Karpov, T. Erdmann, I. Raguzin, M. Al-Hussein, M. Binner, U. Lappan, M. Stamm, K. L. Gerasimov, T. Beryozkina, V. Bakulev, D. V. Anokhin, D. A. Ivanov, F. Günther, S. Gemming, G. Seifert, B. Voit, R. Di Pietro, A. Kiriy, Advanced Materials 2016, 28 (28), 6003–6010, DOI:10.1002/adma.201506295. [3] A. Facchetti, Chemistry of Materials 2011, 23 (3), 733–758, DOI:10.1021/cm102419z. [4] A. J. Heeger, Chemical Society Reviews 2010, 39, 2354–2371, DOI:10.1039/B914956M. [5] H. Klauk, Chemical Society Reviews 2010, 39, 2643–2666, DOI:10.1039/B909902F. [6] S. G. Bucella, A. Luzio, E. Gann, L. Thomsen, C. R. McNeill, G. Pace, A. Perinot, Z. Chen, A. Facchetti, M. Caironi, Nature Communications 2015, 6, 8394, DOI:10.1038/ncomms9394. [7] H. Sirringhaus, T. Kawase, R. H. Friend, T. Shimoda, M. Inbasekaran, W. Wu, E. P. Woo, Science 2000, 290 (5499), 2123–2126, DOI:10.1126/science.290.5499.2123. [8] D. Venkateshvaran, M. Nikolka, A. Sadhanala, V. Lemaur, M. Zelazny, M. Kepa, M. Hurhangee, A. J. Kronemeijer, V. Pecunia, I. Nasrallah, I. Romanov, K. Broch, I. McCulloch, D. Emin, Y. Olivier, J. Cornil, D. Beljonne, H. Sirringhaus, Nature 2014, 515 (7527), 384–388, DOI:10.1038/nature13854. [9] S. Holliday, J. E. Donaghey, I. McCulloch, Chemistry of Materials 2014, 26 (1), 647–663, DOI: 10.1021/cm402421p.

I) Introduction p-Conjugated polymers inherently combine electronic properties of inorganic semiconductor crystals and material characteristics of organic plastics due to their special molecular design. This unique combination has led to developing new unconventional optoelectronic technologies and, further, resulted in the evolution of semiconducting polymers (SCPs) as fundamental components for novel electronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) and organic solar cells (OSCs).[1–5] Moreover, the material flexibility, capability for thin-film formation, and solution processibility additionally allow utilizing modern printing technologies for the large-scale fabrication of flexible, light-weight organic electronics. This especially enables to significantly increase the production speed and, moreover, to drastically reduce the costs per unit.[6, 7] In particular, transistors are the most important elements in modern functional electronic devices because of acting as electronic switches in logic circuits or in displays to control pixels. However, due to molecular arrangement and interactions, the electronic performance of SCPs cannot compete with the one of monocrystalline silicon which is used in state-of-the-art high-performance microtechnology.[5, 8] Nonetheless, intensive and continuing efforts of scientists focused on improving the performance of OFETs, with the special focus on the charge carrier mobility, by optimizing the polymer structure, processing conditions and OFET device architecture. By this, it was possible to identify crucial relationships between polymer structure, optoelectronic properties, microstructure, and OFET performance.[8] Nowadays, the interdisciplinary scientific success is represented by high-performance SCPs with charge carrier mobilities exceeding the value of amorphous silicon.[3, 9] However, further research is essential to enable developing the next generation of electronic devices for application in healthcare, safety technology, transportation, and communication. II) Objective and Results Within the scope of this doctoral thesis, current high-performance p-conjugated SCPs should be studied comprehensively to improve the present understanding about the interdependency between molecular structure, material properties and charge transport. Therefore, the extensive research approaches focused on different key aspects of high charge carrier mobility polymers for organic transistors. The performed investigations comprised the impact of, first, novel design concepts, second, precise structural modifications and, third, synthetic and processing conditions and led to the major findings listed below. 1. The design concept of tuning the p-conjugation length allows to gradually modulate physical material properties and demonstrates that a strong localization of frontier molecular orbitals in combination with a high degree of thin-film ordering can provide a favorable platform for charge transport in p-conjugated semiconducting polymers.[1] 2. The replacement of thiophene units with thiazoles in naphthalene diimide-based p- conjugated polymers allows to increase interchain interactions and to lower frontier molecular orbitals. This compensates the potentially detrimental enhancement of backbone torsion and drives the charge transport to unipolar electron transport, whereas mobility values are partially comparable with those of the respective thiophene containing analogs. 3. p-Conjugated diketopyrrolo[3,4-c]pyrrole-based copolymers can be synthesized within fifteen minutes what, in combination with avoiding aqueous washings and optimizing processing conditions, allowed an increase in morphological and energetic order and, thus, improved the charge transport properties significantly. III) Conclusion The key findings of this doctoral thesis provide new significant insights into important aspects of designing, synthesizing and processing high charge carrier mobility polymers. By this, they can guide future research to further improve the performance of organic electronic devices - decisive for driving the development and fabrication of smart, functional and wearable next-generation electronics. References [1] T. Erdmann, S. Fabiano, B. Milián-Medina, D. Hanifi, Z. Chen, M. Berggren, J. Gierschner, A. Salleo, A. Kiriy, B. Voit, A. Facchetti, Advanced Materials 2016, 28 (41), 9169–9174, DOI:10.1002/adma.201602923. [2] Y. Karpov, T. Erdmann, I. Raguzin, M. Al-Hussein, M. Binner, U. Lappan, M. Stamm, K. L. Gerasimov, T. Beryozkina, V. Bakulev, D. V. Anokhin, D. A. Ivanov, F. Günther, S. Gemming, G. Seifert, B. Voit, R. Di Pietro, A. Kiriy, Advanced Materials 2016, 28 (28), 6003–6010, DOI:10.1002/adma.201506295. [3] A. Facchetti, Chemistry of Materials 2011, 23 (3), 733–758, DOI:10.1021/cm102419z. [4] A. J. Heeger, Chemical Society Reviews 2010, 39, 2354–2371, DOI:10.1039/B914956M. [5] H. Klauk, Chemical Society Reviews 2010, 39, 2643–2666, DOI:10.1039/B909902F. [6] S. G. Bucella, A. Luzio, E. Gann, L. Thomsen, C. R. McNeill, G. Pace, A. Perinot, Z. Chen, A. Facchetti, M. Caironi, Nature Communications 2015, 6, 8394, DOI:10.1038/ncomms9394. [7] H. Sirringhaus, T. Kawase, R. H. Friend, T. Shimoda, M. Inbasekaran, W. Wu, E. P. Woo, Science 2000, 290 (5499), 2123–2126, DOI:10.1126/science.290.5499.2123. [8] D. Venkateshvaran, M. Nikolka, A. Sadhanala, V. Lemaur, M. Zelazny, M. Kepa, M. Hurhangee, A. J. Kronemeijer, V. Pecunia, I. Nasrallah, I. Romanov, K. Broch, I. McCulloch, D. Emin, Y. Olivier, J. Cornil, D. Beljonne, H. Sirringhaus, Nature 2014, 515 (7527), 384–388, DOI:10.1038/nature13854. [9] S. Holliday, J. E. Donaghey, I. McCulloch, Chemistry of Materials 2014, 26 (1), 647–663, DOI: 10.1021/cm402421p.

Cette thèse traite de l'étude du transport de charge à travers les semi-conducteurs organiques au sein de transistors à effet de champ organiques (OFET). Une grande attention a été accordée aux interfaces dans les OFET dont les propriétés ont été accordées pour moduler la réponse transistor. La stabilité de l'appareil en état de commutation et le mécanisme régissant l'injection de charges ont été étudiés systématiquement. Le transport de charge au niveau fondamental à travers les monocouches auto-assemblées comprenant une grande variété des molécules π-conjuguées a été étudié. Dans cette thèse, le processus de transport de charge et différents paramètres affectant ce phénomène sont examinées en détail par la fabrication et la caractérisation de trois terminaux basés sur des architectures OFET et deux dispositifs de jonctions terminales constituées d’une couche mono-moléculaire sur la surface de l'électrode métallique. Parmi les différents aspects relatifs à l'injection de charge dans des transistors organiques macroscopiques à couches minces, un accent particulier a été mis sur l'interface de l’engineering en réglant (i) le diélectrique / l’interface semi-conducteur, et (ii) l'électrode en métal / le semi-conducteur. Pour explorer les aspects régissant le transport de charge dans le canal de l'appareil, nous avons étudié la propriété de (iii) la mobilité intrinsèque dans la semi-conductivité des matériaux et (iv) l'utilisation de mélanges dans la couche active du dispositif. A l’échelle nanométrique, le transport de charge, grâce à une mono-couche moléculaire chimisorbé sur des électrodes métalliques, a été étudié. Pour effectuer la caractérisation électrique sur la mono couche auto-assemblée (SAM), nous avons construit un système de configuration comprenant des alliages eutectiques de gallium et d'indium liquide métallique (GainE) comme électrode. / This thesis deals with the study of charge transport through organic semiconductors incorporated in Organic Field-Effect Transistors (OFETs). Great attention is given to the interfaces in the OFETs and the properties of which were tuned to modulate transistor response. The stability of the device under switching states and the mechanism governing charge injection were studied systematically. In a fundamental level the charge transport through self-assembled monolayers comprising of variety of π-conjugated molecules were investigated. In this thesis the charge transport process and different parameters affecting this phenomenon are investigated in detail by fabrication and characterization of three terminal devices based on OFET architectures and two terminal devices consisting junctions incorporating mono-molecular layer on surface of metal electrode. Among the different aspects governing the charge injection in macroscopic organic thin film transistors particular emphasis was given to the interface engineering by tuning the (i) Dielectric/semiconductor interface, and (ii) Metal electrode/semiconductor. To explore aspects governing charge transport within the channel of the device we investigated the property of (iii) semiconductor intrinsic mobility and (iv) usage of blends in the active layer of the transistor. On the nanoscale the charge transport through a mono molecular layer chemisorbed onto metal electrodes was investigated. To perform electrical characterization on self-assembled monolayer (SAM) a custom in-house setup comprising of eutectic alloy of liquid metallic gallium indium (GaInE) probe electrode was built.