In order to analyze the correlation between charge transport and structural properties in conjugated oligomers, sexithiophene, 6T, was substituted by hexyl groups, both on the terminal a positions (a,cvDH6T) and as pendant groups in the ß position (ß,ß' 6 ). Structural characterizations by X-ray diffraction show that vacuum-evaporated thin films of 6T and , consist of layered structures in a monoclinic arrangement, with all-trans planar molecules standing on the substrate. When compared to 6T, , 6 is mainly characterized by a very large increase of molecular organization at the mesoscopic level, evidenced by a much longer range ordering. Electrical characterizations indicate that the conductivity of , 6 is largely anisotropic, with a ratio of 120 in favor of the conductivity parallel to the substrate plane, i.e. along the stacking axis. The charge carrier mobility, determined on field-effect transistors fabricated from these conjugated oligomers, also shows an increase by a factor of 25 when passing from 6T to , 6 , reaching a value of 5 X 10-2 cm* 12 3V-1 s-1. In contrast, ß,ß' 6 presents very low conductivity and mobility, the latter being below detection limit. These results are attributed to the self-assembly properties brought by alkyl groups in the a,w position.

Spin information processing is a possible new paradigm for post-CMOS (complementary metal-oxide semiconductor) electronics and efficient spin propagation over long distances is fundamental to this vision. However, despite several decades of intense research, a suitable platform is still wanting. We report here on highly efficient spin transport in two-terminal polarizer/analyser devices based on high-mobility epitaxial graphene grown on silicon carbide. Taking advantage of high-impedance injecting/detecting tunnel junctions, we show spin transport efficiencies up to 75%, spin signals in the mega-ohm range and spin diffusion lengths exceeding 100 {\mu}m. This enables spintronics in complex structures: devices and network architectures relying on spin information processing, well beyond present spintronics applications, can now be foreseen

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The crystalline orientation of oligothiophenes has a profound effect on the electronic properties of the materials, which are of interest for example in the construction of all‐organic field‐effect transistors. Here, an X‐ray diffraction study of oligothiophene films is reported and the possible routes to improving the crystalline orientation discussed. It is found that α‐substitution or indeed heating of the substrate can lead to increased orientation of the oligomers.

We report on the structural impact on graphene and multi-layers graphene of the growth by sputtering of tunnel barriers. Sputtered Al2O3 and MgO barriers were chosen for their well-known efficiency as spin injectors in spintronics devices. The impact of the growth on the structure of graphene and up to 4-layer flakes was analyzed by Raman spectroscopy. This study reveals that for Al2O3 growth, the impact is moderate for a monolayer and decreases sharply for bilayers and above. In the case of MgO all the flakes underwent a strong amorphization. Moreover, this reveals that while single layer graphene is believed to offer the best spin transport properties, the better robustness of multilayer graphene may ultimately make it a better choice for spintronics devices.