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The project is about piezoelectric energy harvesters and piezoelectric bio-organic materials.Nowadays, various kinds of energy harvesters based on micro or nano materials are appliedinmanyelectronic applications, such as wearable devices and electricity generators. Amongthem, thepiezoelectric effect-based energy harvesters are more attractive in research and industryfields. Inrecent years, piezoelectric biomaterials become a popular option because they are availabletocouple electrical and mechanical energy in a biological, ecofriendly systemto generate electricityinreal time. Among them, γ- glycine crystals have been recently synthesized in wafer scale throughasimple polyvinyl alcohol (PVA)-assisted evaporation process exhibiting good piezoelectricperformance. However, so far there are no metal-free energy-harvesting devices basedonPVA-glycine film to enable green manufacturing. In this project, we proposed the direct inkwritingorganic PEDOT:PSS electrodes and PVA-glycine-PVA piezoelectric crystals to fabricate metal-freeenergy harvesters. The output voltage reaches 1.5 V at a load resistance of 500 MΩandunderaforce of 10 N. The performance is comparable to other glycine-based devices in recent literature.Our scalable, sustainable and low-cost printing process is expected to greatly contribute tothefieldof biomaterials-based piezoelectric energy harvesting. / Projektet handlar om piezoelektriska energiskördare och piezoelektriska bioorganiska material. Nuförtiden används olika typer av energiskördare baserade på mikro- eller nanomaterial i mångaelektroniska applikationer, såsom bärbara enheter och elgeneratorer. Bland dem är de piezoelektriskaeffektbaserade energiskördarna mer attraktiva inom forsknings- och industriområden. På senare år harpiezoelektriska biomaterial blivit ett populärt alternativ eftersom de är tillgängliga för att koppla elektrisk och mekanisk energi i ett biologiskt, miljövänligt system för att generera elektricitet i realtid. Bland dem har γ-glycinkristaller nyligen syntetiserats i waferskala genom en enkel polyvinylalkohol (PVA)-assisterad förångningsprocess som uppvisar god piezoelektrisk prestanda. Än så länge finnsdet dock inga metallfria energiskördande enheter baserade på PVA-glycinfilm för att möjliggöra gröntillverkning. I detta projekt föreslog vi direkt bläckskrivande organiska PEDOT:PSS-elektroder ochPVA-glycin-PVA piezoelektriska kristaller för att tillverka metallfria energiskördare. Utspänningennår1,5 V vid en belastningsresistans på 500 MΩ och under en kraft på 10 N. Prestandan är jämförbar medandra glycinbaserade enheter i nyare litteratur. Vår skalbara, hållbara och billiga utskriftsprocess förväntas i hög grad bidra till området för biomaterialbaserad piezoelektrisk energiskörd.

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Exploring new technologies that can meet the world’s energy demands in an efficient and clean manner is critically important due to the depletion of natural resources and environmental concerns. Dye-sensitized solar cells (DSSCs) are low-cost and clean technology options that use solar energy efficiently and are being intensively studied. How to further reduce the cost of this technology while enhancing device performance is one of the demanding issues for large scale application and commercialization of DSSCs. In this research dissertation, four main contributions are made in this regard with the motivation to reduce further cost of DSSC technology. Firstly, ~10% efficiencies were achieved after developing understanding of key concepts and procedures involved in DSSCs fabrication. These efficiencies were achieved after step-by-step modifications in the DSSC design. Secondly, carbon nanotubes (CNTs) were successfully employed as an alternative to Pt in the counter electrodes of DSSCs. DSSCs fabricated with CNTs were ~86% as efficient as Pt-based cells. Non-aligned CNTs were successfully grown using four different CVD methods and finally, multi-walled vertically aligned CNTs (MW-VACNTs) were synthesized using water-assisted chemical vapor deposition (WA-CVD). Thirdly, carbon derived from pyrolysis of nanocrystalline cellulose (NCC) was successfully employed in counter electrodes of DSSCs instead of Pt. DSSCs with NCC were ~58% as efficient as Pt-based DSSCs. Fourthly, novel organic metal-free dyes were designed and employed instead of commonly used Ru-based dyes. DSSCs with these novel sensitizers were ~62% as efficient as those using the conventional Ru-based dyes. Characterization techniques including current-voltage measurements, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetery (CV), thermogravimetric analysis (TGA), small angle x-ray scattering (SAXS), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) were used.

Deux carbènes N-hétérocycliques (NHCs) de type imidazol-2-ylidène ont été étudiés en tant qu’amorceurs organiques pour la polymérisation directe de monomères vinyliques de type (méth)acrylates d’alkyle, principalement le méthacrylate de méthyle(MMA), en l’absence tout autre activateur. Une différence de réactivité a été mise en évidence en fonction des substituants du carbène et de la nature du substrat. Des études théoriques ont permis de rationaliser les résultats expérimentaux par l’influence des effets électroniques et stériques intervenant au cours des réactions mises en jeu. Un NHC en particulier a été ensuite utilisé comme véritable catalyseur de la polymérisation du MMA en présence d’alcools comme amorceurs. En utilisant des macroamorceurs hydroxylés de type poly(oxyde d’éthylène), des copolymères amphiphiles ontété ainsi synthétisés. Des études théoriques ont encore une fois permis d’identifier les mécanismes réactionnels de cette polymérisation. Enfin, des paires de Lewis composées d’un acide à base de silicium et d’une base de typeNHC ou phosphine trialkyle(aryle) ont été ensuite utilisées comme système d’activation de polymérisation du MMA. Ce type de polymérisation est basé sur une activation duale du monomère par effet coopératif de la base et de l’acide. / The reactivity of imidazol-ylidene N-heterocyclic carbenes (NHCs) as direct initiators for the polymerization of miscellaneous (meth)acrylic monomers, mainly methylmethacrylate (MMA), has been screened in the absence of any other co-activator.Different reactivities have been observed according to the structure of the NHC and thenature of the substrate. Computational studies allowed rationalizing steric and electroniceffects involved in these reactions.The use of a peculiar NHCs as catalyst for the polymerization of MMA using alcohols as initiators has then been investigated. This simple and efficient method also allows achieving amphiphilic block copolymers by using hydroxylated poly(ethylene oxide)s asmacro-initiators. Combined computational and experimental investigations have provided insights into the mechanism of polymerization.Various Lewis pairs including a silicon-based compound as acid and NHC or a trialkyl(aryl)phosphine as base, have been investigated to trigger an efficient polymerization of MMA.In this case, the polymerization is expected to proceed via a cooperative/dual activation mechanism.

Core- and Valence Photoelectron Spectroscopy (PES), X-ray- and Ultraviolet-Visible Absorption Spectroscopy (XAS and UV-Vis), Scanning Tunneling Microscopy (STM) and Density Functional Theory (DFT) calculations are used to study the electronic and geometrical structure of a class of macro-cyclic molecules, Phthalocyanines (Pc), on surfaces. These molecules are widely studied due to their application in many different fields. Multilayer and monolayer coverages of Iron Phthalocyanine (FePc) and metal-free Phthalocyanine (H2Pc) deposited on different surfaces are investigated in order to get insight in the electronic and geometrical structure of the obtained overlayers, of crucial importance for the understanding of the film functionality. Sublimation of molecular thick films on Si(100) and on conducting glass results in films with molecules mainly oriented with their molecular plane orthogonal to the surface. Ex-situ deposited H2Pc films on conductive glass show different molecular orientation and morphology with respect to the vacuum sublimated films. We study the monolayer adsorption structure of FePc and H2Pc and compare our results with other Pc’s adsorbed on graphite. We find that the molecular unit cell and the superstructure is characteristic for each Pc adsorbed on graphite, even if the geometrical size of the compared molecules is the same. The PE- and XA- spectra of FePc on graphite are essentially identical for the mono- and multilayer preparations, evidencing weak intermolecular and molecular-substrate interactions of van der Waals nature. Furthermore, we characterize Pc’s on InSb (001)-c(8x2). The substrate In rows are observed to be the adsorption site for Pc’s. We find that the growth of the two-dimensional islands of FePc is prolonged in the [-110] direction, in contrast to ZnPc adsorbed on the same substrate at room temperature. We interpret this result as an indication that the adsorption is controlled by the substrate corrugation observed at 70 K.

Le motif biaryl contenant la pyridine représente une structure omniprésente dans la chimie organique et médicinale. Ainsi, le développement de méthodes fiables de synthèse est continuellement désiré. Traditionnellement, les cycles azotés biarylés sont efficacement synthétisés par des réactions de couplage croisé catalytique. Cependant, la pyridine peut être difficilement fonctionnalisée en position C-2 compte tenu de sa déficience en électrons. Cette propriété limite son utilisation en tant que partenaire nucléophile dans les réactions de couplage croisé. Par exemple, dans le couplage de Suzuki-Miyaura, l’acide 2-pyridyle boronique est connu pour son instabilité. À l’inverse, les organométalliques du 2-pyridyle sont peu réactifs pour faire des réactions de substitution aromatique électrophile. La synthèse des pyridines 2-substituées est par conséquent un défi qui reste difficile à relever. La première partie de ce mémoire est consacrée au développement récent des méthodes pour résoudre les problèmes de couplage avec des nucléophiles 2-pyridyles. En particulier, les approches classiques comme le couplage modifié de Suzuki-Miyaura, l’activation de liaison C-H des composés pyridinium N-activés, et l’arylation directe du cycle pyridine sont présentées. De plus, les approches alternatives qui utilisent la partie pyridine comme partenaire électrophile dans la réaction couplage avec les réactifs organométalliques sont également discutées. Dans la deuxième partie de ce mémoire, une méthode de couplage croisée entre des esters de sulfonate de 2-pyridyles et des organolithiens est rapportée. Une variété de pyridines 2-substituées a été synthétisées avec succès en faisant réagir des sulfonates de pyridine avec des organolithiens (aryl, alkane, heteroaryle lithium) à basse température. La méthode permet également de s’affranchir de l’utilisation d’un quelconque métal de transition. Des études mécanistiques montrent que le processus impliquant les composés lithiés s’apparente à une réaction de substitution nucléophile aromatique. Cependant, le mécanisme diffère lorsque la réaction met en jeu des réactifs de Grignard, où un processus de couplage entre deux ligands d’un intermédiaire σ-sulfurane peut être impliqué. / Biaryl compounds containing the pyridine moiety represent a ubiquitous structure in both organic and medicinal chemistry. Therefore, finding new and reliable approaches for their synthesis is still of interest. Traditionally, azine containing biaryls are efficiently synthesized via transition-metal catalyzed cross-coupling reactions. However, due to its π-deficient nature, pyridine cannot be easily functionalized at the C-2 position to serve as nucleophile partner. For examples, in the Suzuki-Miyaura cross-coupling reaction, 2-pyridyl boronates are well known for their instability. 2-Pyridyl organometallics undergo electrophilic aromatic substitution poorly. Thus, the synthesis of 2-substituted pyridines remains a challenging task. The first part of the thesis focuses on the recent methods to address the coupling issues of 2-pyridyl nucleophiles in cross-coupling reactions. Of note, the classical methods including Suzuki-Miyaura cross-coupling reactions, C-H activation of N-activated pyridinium species, and direct coupling reaction of pyridine are presented. Alternative approaches using the pyridine moiety as an electrophilic entity in the coupling with organometallic reagents are also discussed. In the second part of the thesis, a transition metal-free desulfinative cross-coupling reaction of 2-pyridyl sulfonates with organolithium reagents is reported. A variety of 2-substituted pyridines were successfully synthesized in good yields, by treatment of neopentyl 2-pyridyl sulfonates and phenyl 2-pyridyl sulfonate with aryl, alkyl, and heteroaryl-lithium reagents at low temperature. Mechanistic studies showed that the coupling reaction with lithium reagents undergoes an SNAr pathway. However, a ligand coupling process of a σ-sulfurane intermediate may be involved in the reaction with Grignard reagents to form the biaryl.

Les travaux de cette thèse sont centrés sur le développement de systèmes moléculaires en solution homogène pour la production photocatalytique de dihydrogène dans l'eau utilisant des catalyseurs de cobalt à ligands pentadentate tétrapyridinique ou tétra- et pentaaza macrocycliques. Associés au photosensibilisateur et à l’ascorbate comme donneur d’électron sacrificiel, les complexes à ligands macrocycliques présentent d’excellentes performances pour la production d’H2, bien supérieures à celles des complexes à ligands polypyridiniques en termes d’efficacité et de stabilité, en raison de la grande stabilité de leur état réduit «Co(I)». Enfin, [Ru(bpy)3]2+ a pu être substitué par un colorant organique très robuste du type triazatriangulénium conduisant à un système photocatalytique encore plus performant. Ces résultats démontrent que les colorants organiques sont une alternative viable aux photosensibilisateurs à base de métaux nobles, même en milieu aqueux acide. / The work of this manuscript is focused on the design of molecular systems in homogeneous solution for photocatalytic production of molecular hydrogen in water using cobalt catalysts with pentadentate tetrapyridinic and tetra- and pentaza macrocyclic ligands. In association with [Ru(bpy)3]2+ as photosensitizer and sodium ascorbate as sacrificial electron donor, the macrocycle based catalysts display high performances for H2 production, far exceeding those of the polypyridine based catalysts, both in terms of activity and stability, because of the stability of their reduced state «Co(I)». Finally, [Ru(bpy)3]2+ was successfully substituted with a robust organic dye belonging to the triazatriangulenium family, leading to an even more efficient photocatalytic system. These results demonstrate well that organic dyes are a truly efficient alternative to noble metal based photosensitizers, even in acidic aqueous medium.