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Le fullerène C60 est une molécule sphérique composée exclusivement d'atomes de carbone. Ce composé possède une surface aromatique convexe homogène et peut s'associer, entre autres, avec des molécules possédant des surfaces aromatiques par des interactions non-covalentes. Le triptycène est une molécule en forme de "Y" qui possède des surfaces aromatiques convexes. Cette molécule possède l'habileté de s'associer avec le C60 par des interactions de type π qui sont amplifiées par la complémentarité des surfaces concaves et convexes impliquées dans les arrangements cristallins. Nous avons synthétisé des dérivés triptycényles portant des groupements fonctionnels aux extrémités des bras de ce noyau de façon à étendre les cavités disponibles pour interagir avec le C60. En effet, nous avons découvert que les atomes de chlore, de brome et d'iode ainsi que les groupements méthyle permettent d'étendre les surfaces disponibles pour interagir avec les fullerènes C60 et C70. Nous avons étudié les associations entre les dérivés triptycényles et les fullerènes par l'analyse des structures cristallographiques résolues par diffraction des rayons-X. De plus, nous avons étudié les associations entre les molécules considérées par l'analyse des surfaces d'Hirshfeld entourant les fullerènes. Découlant de ces études, l'effet d'amplification des atomes de chlore, de brome et d'iode ainsi que les groupements méthyle a été employé pour identifier de nouveaux solvants aptes à solubiliser efficacement le C60. / The fullerene C60 is a spherical molecule made up exclusively of carbon atoms. The surface of this compound is homogenous, convex and aromatic. As a result, C60 can associate with other aromatic molecules via non-covalent π-stacking interactions to form supramolecular assemblies. The triptycene is a "Y"-shaped molecule with concave aromatic surfaces. This molecule can thereby interact with C60 and form crystals through amplified π-stacking interactions resulting from the concave/convex complementary arrangement. In the course of our work, we made a series of new triptycene derivatives with functional groups added to the periphery of the aromatic core. In particular, we found that methyl groups, as well as atoms of chlorine, bromine and iodine, can be placed on the extremities of the triptycene core to expand the concave cavities available to interact with C60 and C70. We studied the non-covalent interactions between fullerenes and triptycene derivatives using X-ray crystallography. Furthermore, Hirshfeld surfaces have been used to map the interaction patterns around fullerene surfaces. In addition, we have found that aromatic solvents that are properly functionalized with halogen atoms and methyl groups have a special ability to solubilize C60.

Organic solar cells are cheaper and much easier to fabricate than the conventional inorganic solar cells, but they suffer from low efficiencies due to low carrier mobilities in organic films. In this study Copper Phthalocyanine (CuPc) and Buckminster Fullerene (C60) based Schottky diodes were fabricated on ITO coated glass substrates to study their performance and a study of the effect of thickness on the cell parameters of CuPc Schottky diodes was made. Also, TiO2 based devices were studied to see the effect of TiO2 layer on the cell parameters. The J-V curves were analyzed for series resistance, diode ideality factor and reverse saturation current density. The devices were also characterized by SEM and XRD measurements.

A standard procedure for P3HT:PCBM bulk-heterojunction solar cells has been developed. Fabrication conditions, such as environment; solution concentration, thickness of active layer or post-treatment methods are systematically optimized. The best device performance is obtained by slow-drying spin-coated P3HT:PCBM (1:0.8) blend layer with DCB as solvent. C60:LiF composite films with up to 80% LiF concentration as hole blocking layer have been developed to significantly increase power conversion efficiencies of OPV devices. The short-circuit current density is greatly enhanced, without sacrificing open-circuit voltage and fill factor. Due to its superior oxygen diffusion blocking effect, the C60:LiF composite layer also can provide a more effective passivation film than a thin LiF layer, resulting in an impressive enhancement in air stability of devices.

A standard procedure for P3HT:PCBM bulk-heterojunction solar cells has been developed. Fabrication conditions, such as environment; solution concentration, thickness of active layer or post-treatment methods are systematically optimized. The best device performance is obtained by slow-drying spin-coated P3HT:PCBM (1:0.8) blend layer with DCB as solvent. C60:LiF composite films with up to 80% LiF concentration as hole blocking layer have been developed to significantly increase power conversion efficiencies of OPV devices. The short-circuit current density is greatly enhanced, without sacrificing open-circuit voltage and fill factor. Due to its superior oxygen diffusion blocking effect, the C60:LiF composite layer also can provide a more effective passivation film than a thin LiF layer, resulting in an impressive enhancement in air stability of devices.

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Despite the rapid growth in nanotechnology, very little is known about the unintended health or environmental effects of manufactured nanomaterials. The development of nanotechnology risk assessments and regulations requires quantitative information on the potential for exposure to nanomaterials. In addition, to facilitate life-cycle assessments and inhalation toxicology studies, robust methods are needed to generate aerosolized engineered nanoparticles. We conducted a set of field studies to measure the fine particle mass concentrations (PM2.5) as well as nanoparticle number concentrations and size distributions in two nanomaterial manufacturing facilities. Measurements were performed near the reactor, in the breathing zone, and at a background site. Increases in PM2.5 and particle number concentrations were associated with physical handling of nanomaterials. The highest PM2.5 concentration observed was 2700 ug m-3 during sweeping of the reactor in the commercial plant. In most cases, an increase in the number of sub-100 nm particles accounted for the increase in total number concentrations. The results of this research can be used to develop guidelines for workplace regulations to minimize workers' exposure to nanoparticles. Furthermore, we used an atomizer to aerosolize C60 aggregates from a fullerene-water suspension. Measurement of particle size distributions and number concentrations showed that increasing the initial fullerene concentration resulted in increased number of aerosolized particles, while the average size of particles remained relatively constant. To return the aerosolized fullerenes into water, we passed the aerosol sample through an impinger. Reducing the flow rate through the impinger resulted in an increase in the collection efficiency of airborne nanoparticles. / Master of Science

Cette thèse a pour but d’étudier la structure à l’échelle nanométrique et micrométrique de matériaux d’intérêt pour la spintronique organique, en se focalisant notamment sur deux aspects cruciaux pour la qualité des dispositifs : les interfaces molécules/métaux et les couches organiques. Pour pouvoir confronter nos résultats aux prédictions théoriques, nous avons utilisé des monocristaux métalliques et effectué des dépôts de molécules sous ultravide, permettant la réalisation d’échantillons de grande qualité. Nous avons concentré notre étude sur deux systèmes, l’un à base de C60 et de Cobalt et l’autre à base de molécules à transition de spin et d’Or. Pour élucider la structure de nos échantillons, nous avons réalisé in situ des mesures de microscopie à effet tunnel et de diffusion des rayons X, deux techniques complémentaires permettant respectivement l’obtention d’informations locales et globales sur le système. Les résultats obtenus ont été comparés à des calculs ab initio réalisés sur ces mêmes systèmes. Concernant le dépôt de molécules de C60 sur un substrat Co(0001), nous avons notamment pu mettre en évidence que le recuit de l’échantillon entraîne une transition structurale de l’interface, avec la création de lacunes dans le substrat sous chaque molécule, formant ainsi un réseau périodique. La couche moléculaire non recuite exhibe en outre une grande cristallinité. Le dépôt de Cobalt sur ce cristal moléculaire entraîne une contraction de ce dernier, due à la diffusion des atomes de Cobalt dans les sites interstitiels. Enfin, concernant les molécules à transition de spin [FeII (HB (3,5-(CH3)2Pz)3)2] déposées sur Au(111), nous avons mis en évidence une relation d’épitaxie inattendue entre le réseau moléculaire et le substrat / The aim of this thesis is to study at micrometric scale and nanoscale the structure of materials of interest for organic spintronics, focusing in particular on two crucial aspects to obtain good devices quality: molecular/metal interfaces and organic layers. In order to compare our results with theoretical predictions, we have used metallic single crystals and molecular deposition under ultra-high vacuum, allowing the obtention of high quality samples. We focused our study on two systems, one based on C60 and Cobalt and the other based on spin crossover molecules and Gold.To elucidate the structure of our samples, we used scanning tunneling microscopy and X-ray scattering, two techniques that are complementary, one probing the local organization and the other the global otganization of the system. The results obtained were compared to ab initio calculations carried out on the same systems. Regarding the deposition of C60 molecules on a Co (0001) substrate, we have been able to demonstrate that the annealing of the sample leads to a structural transition of the interface, with the creation of Cobalt vacancies under each molecules, forming a periodic network. Before annealing, the molecular layer also exhibits high crystallinity. The Cobalt deposition on this molecular crystal causes a contraction of the lattice, due to Cobalt diffusion into interstitial sites. Finally, concerning the [FeII (HB (3,5- (CH3) 2Pz) 3) 2] spin-crossover complex deposited on Au (111), we have demonstrated an unexpected epitaxial relationship between the molecular lattice and the substrate

A long-term goal within the field of organic electronics has been to developflexible and functional devices, which can be processed and patterned withlow-cost and energy-efficient solution-based methods. This thesis presents anumber of functional paths towards the attainment of this goal via thedevelopment and demonstration of novel fabrication and patterningmethods involving the important organic-semiconductor family termedfullerenes.Fullerenes are soccer-shaped small molecules, with two often-employedexamples being the symmetric C60 molecule and its more soluble derivative[6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We show that PCBM canbe photochemically transformed into a dimeric state in a bi-excited reactionprocess, and that the exposed material features a significantly reducedsolubility in common solvents as well as an effectively retained electronmobility. This attractive combination of material properties allows for adirect and resist-free lithographic patterning of electronic PCBM films downto a smallest feature size of 1 µm, using a simple and scalable two-stepprocess constituting light exposure and solution development. In a furtherdevelopment, it was shown that the two-step method was useful also in thearea-selective transformation of fullerene/conjugated-polymer blend films,as demonstrated through the realization of a functional complementary logiccircuit comprising a 5-stage ring oscillator.In another project, we have synthesized highly flexible, single-crystal C60nanorods with a solution-based self-assembly process termed liquid-liquidinterfacial precipitation. The 1-dimensional nanorods can be deposited fromtheir synthesis solution and employed as the active material in field-effecttransistor devices. Here, it was revealed that the as-fabricated nanorods canfeature an impressive electron mobility of 1.0 cm2 V-1 s-1, which is on par withthe performance of a work horse in the transistor field, viz. vacuumdeposited amorphous Si. We further demonstrated that the processability ofthe nanorods can be improved by a tuned light-exposure treatment, duringwhich the nanorod shell is polymerized while the high-mobility interior bulkis left intact. This has the desired consequence that stabile nanoroddispersions can be prepared in a wide range of solvents, and we anticipatethat functional electronic devices based on solution-processable nanorodscan be realized in a near future.