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The theory of conductivity in organic metals and a review of organic π-electron donors is introduced in Chapter One, outlining some of die many variations that have been made to the tetrathiafulvalene (TTF) molecule, the donor component in the first true organic metal. A range of new' alkylseleno-substituted ethanediylidene-2,2’-bis(l,3-dithiole) donors have been efficiently synthesised. These compounds form semi-conducting charge- transfer complexes with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ). The synthesis, electrochemistry. X-ray crystal structure and magnetic properties are presented (Chapter Two). Various 1,3-dithiolium cations and 1,3-dithiole anions have been used in the synthesis of compounds targeted as high-spin systems (Chapter Three). The theory of organic ferromagnetism is discussed, and various compounds with interesting magnetic and redox properties have been prepared. Chapter Four deals with the synthesis of a series of conjugated, multi-1,3-dithiole, multi-chalcogen, π-electron donors. These compounds are members of the dendralene family of hydrocarbons and the crystal structure of a tricyclic [3]-dendralene is presented. The formation of semi-conducting charge-transfer salts is also discussed. Multistage redox behaviour of a new anthraquinodimethane derivative of TTF has been observed (Chapter Five), and cyclic voltammetic data and X-ray crystal structures of such systems are presented.

Cette thèse est porté sur l'étude du transport électronique dans différents matériaux organiques semi-conducteurs, considérés comme candidats potentiels pour des applications en Electronique de Spin Organique. Pour rendre possible la diffusion d'un courant polarisée en spin à l'intérieur d'un semi-conducteur (injection-transport-détection), le mécanisme de transport et la mobilité des porteurs de charge, ainsi que la nature et la valeur de la résistance de contact de l'interface séparant matériau organique et électrodes métalliques ferromagnétiques, doivent répondre à des critères très stricts. Tous les dispositifs sont en géométrie latérale. Nous étudions trois matériaux organiques différents: des fibres supramoléculaires auto-assemblées, une encre de nana-flocons de graphene exfolié en phase liquide et un polymère semi-conducteur fortement dopé en forme de couche mince. Nos résultats montrent que les conditions sont partiellement respectées, mais que des défis demeurent. / In this thesis, we study the electronic charge transport properties in different high mobility organic semiconductors considered as possible candidates for applications in Organic Spintronics. Stringent conditions are needed to make possible the diffusive transport of a spin-polarized current through an organic spacer (injection-transport-detection): the mechanism of charge transport and the carriers mobility, as well as the interface between the organic semiconductor and the ferromagnetic metallic electrodes, should meet special criteria. Our devices are in lateral geometry. We investigate three organic materials, all compatible with wet processing of organic electronics: supramolecular fibers self-assembled by light irradiation, an ink of liquid-phase exfoliated graphene nano-sheets and a conjugated polymer semiconductor thin film exposed to strong electrochemical doping. We observe that the criteria are partially matched, but some challenges are still present.