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1
Schonebeck, Franziska. "Super electron donors powerful reductions performed by neutral organic molecules". Thesis, University of Strathclyde, 2007. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21732.
Abstract (sommario):
This project aims to explore the ability of organic molecules to transfer electrons and is based on the recent development within the Murphy group of a novel organic molecule, called Super-S.E.T. reagent 1, that allows the reduction of unactivated aryl and alkyl iodides. My study investigates the scope of donor 1 as a reducing agent and extends the study to a more powerful donor 2. Chapter One provides an introduction to the world of electron transfer. After giving a theoretical background, synthetic applications of electron transfer are highlighted, in particular using metal chemistry, electrochemical and photochemical methods. This chapter also discusses the use of sulfones and sulfonamides as challenging substrates for electron transfer. Finally the field of neutral organic electron-donors, which form the basis of my studies, is introduced. Chapters Two to Seven then summarise my work. Chapter Two and the second part of Chapter Six highlight my adventures in investigating the chemistry of donor 1. Until now, donor 1 is known to reduce efficiently only specific aryl and alkyl iodides. This report (i) highlights the scope and limitations of donor 1 in the reduction of different aryl iodide substrates and of aryl halides other than iodides and (ii) discusses the application of donor 1 in the selective reduction of an ortho- over an analogous para-aryl iodide in substrate 3 and (iii) recounts the successful isolation of the first adduct of the donor, i.e. 4. Chapter Three to Six deal with the exploration of the power of Super-S.E.T. reagent 2. This donor was successfully applied as a powerful reducing agent in the reductive cleavages of a number of activated sulfones and sulfonamides, giving the reduced counterparts in excellent yields. Further, strong evidence for the first example of a Julia olefination using a neutral organic electron donor has been given. It was also shown that the reagent has remarkable reducing power, being the first neutral organic reagent to generate highly reactive aryl anion intermediates in the reduction of aryl 3 bromides and iodides. Ester substrates 5,6 and 7 were synthesised and investigated as mechanistic probes in that context. The chemistry of donor 2 with aliphatic halides was investigated, leading to the formation of aldehydes in DMF or DMA. It was found that the proportion of aldehyde can be increased with more equivalents of donor 2, ultimately leading to the aldehyde being the exclusive product. Using non-polar solvents, such as diethyl ether, donor 2 was transformed into a powerful reducing agent for alkyl bromides, reacting at room temperature and showing radical chemistry. Selective reduction of an alkyl over aryl bromide was achieved also. Intriguing reactivity was observed with anthracene esters, giving the dihydroester as one of the major products, if a carbene is added, and dihydroanthracene if not. After a summary of results in Chapter Seven, Chapter Eight presents the experimental procedures and analytical data for the compounds discussed in Chapters Two to Six.
2
Cumine, Florimond. "Studies on organic electron donors and their applications in chemistry". Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=29432.
Abstract (sommario):
Electron transfer reactions using organic donors have been and are still successfully applied in the Murphy group to perform reductions usually requiring heavy metals. This thesis focuses on several organic electron donors used to: (i) promote the cross-coupling reaction between aryl halides and benzene, which was also studied with computational experiments, (ii) cleave carbon-oxygen bonds and (iii) reduce nitrobenzenes and azobenzenes. In addition, computational analysis of controversial literature proposals for a radical/electron transfer mechanism for ring-forming reactions of alkoxide allenes and amide allenes is reported and supports an anionic rather than a radical process. Chapter Two highlights the ability of diketopiperazines 1-4 to promote the cross-coupling reactions of aryl halides 5-16 with benzene in the presence of potassium tert-butoxide 17 to form biaryls 18-24 via electron transfer [graphic of electron transfer process]. It also investigates the different outcomes of the reaction when a diketopiperazine is used or not, providing evidence for formation of a benzyne intermediate which can lead to both the coupling product with benzene (when aryl iodides are used) and to tert-butoxybenzenes. Chapter Three explores electron transfer reactions that lead to alkyl aryl ether deprotection. It highlights that tert-butyllithium 25 performs this deprotection and shows the series of reactions that led to evidence of an anionic addition of phenyllithium 26 to benzene and also of tert-butyllithium 25 to benzene [graphic of base-induced process and additions to Benzene with oxidative termination]. Chapter Four focuses on a 4-DMAP-derived organic electron donor 32, commonly referred to as 'DMAP donor', that reduces nitrobenzene 34 and azobenzene 36, amongst others, under UV activation or thermal conditions, via successive single electron transfers. This chapter also discusses the unlikely possibility of an electron transfer from the DMAP donor 32 to the 1,2-diphenylhydrazine dianion 38 leading to the formation of aniline dianion 39. More rational mechanistic considerations involving the reduced diphenylhydrazine and dication 33 will be described to explain the formation of aniline 35 [graphic of DMAP electron donor]. Chapter Five is a computational study of the 5-endo-trig cyclisation of alkoxideallenes and amide-allenes, discussing the process involved (electron transfer or direct intramolecular anionic cyclisation) and comparing it with the, non-experimentally observed, 4-exo-dig cyclisation [DMSO graphic]. Chapter Six provides the detailed experimental procedures and data for the compounds that were synthesised and reported in this thesis.
3
Buker, Nicholas D. "Guanidine donors in nonlinear optical chromophores /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8669.
4
Chua, Jonathan. "Exploring new reactions with Organic Electron Donors and the complexities of the Birch reduction". Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26437.
Abstract (sommario):
Reductive σ-bond cleavages of challenging substrates under metal-free, mild conditions have recently been achieved with photoactivated super-electron donor (SED). These include (but are not limited to) C-O bonds of benzylic ethers and esters, C-N bonds of benzylic sulfonamides and aromatic amides. This work has successfully widened the substrate scope of reduction by SED to include i) the C-O bond cleavages of phenolic esters and aryl ethers and ii) the C-S bond cleavages of aromatic sulfides, sulfoxides and sulfones. Previously it was also discovered that the X-N bond of several amides were reductively cleaved via intramolecular electron-shuttling instead of the more conventional through-bond electron transfer. This mode of reduction by SED is not well-explored. To this end, several ester and amide-based substrates were synthesised in an attempt to expand the scope of this electron-shuttling mechanism induced by SED. This study has also been successful, with the electron-shuttling effect thought to be responsible for the C-C bond cleavage of 14 [illustration not shown], resulting in the production of 15 [illustration not shown]. Perhaps the most powerful reducing agent in the synthetic industry is the "solvated electron" which is conveniently prepared during the Birch reduction. In this work, the Birch reduction conditions were successfuly applied, in an unprecedented way, to the C-S bond cleavage of methyl-coenzyme M (MeCoM). The experimental results have the potential to contribute significantly towards our current understanding of MeCoM reductase activity. This study has also highlighted the complex nature of the Birch reduction; by simply switching from sodium to lithium, reactivity and regioselectivity could be significantly altered. Presently, some details of the mechanism for the observed reduction(s) remain unsolved.
5
Anderson, Greg. "Towards the rational development of organic super electron donors for transition metal-free biaryl coupling". Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27424.
Abstract (sommario):
Within both the industrial and academic laboratory, the coupling of two aryl moieties is a process of significant synthetic use. To achieve such transformations typically requires the use of expensive transition metal catalysts that cannot always be recovered from the reaction mixtures. Consequently, the investigation of biaryl coupling reactions without the requirement for any such catalysts has been of key interest amongst chemists. Throughout the literature, a variety of simple organic molecules have been incorrectly termed as “ligands” or “catalysts” with respect to their role in transition metal-free biaryl coupling reactions. We have discovered that these molecules in fact undergo reaction with a strong base to form an organic electron donor in situ, capable of reducing aryl iodides to their respective radical anions. This reduction can then initiate a cyclic radical reaction mechanism, furnishing the desired biaryl product. A number of key structures, identified through experimental studies, have helped to guide the early theoretical investigations. These allowed the feasibility of the formation of organic electron donors in situ, based on their free energy profiles, to be investigated. The mechanistic understanding gained from these calculations was then applied to rationalise the reactivity of other molecules shown to effectively promote this chemistry. To fully understand the reactivity in this chemistry, the computational application of Marcus Theory was called upon to predict the relative reducing ability of the proposed donor species. Shortcomings of the present protocol for the computational application of Marcus Theory prompted the development of a novel reaction model utilising electron transfer complexes. These complexes more accurately capture the internal reorganisation energy associated with the electron transfer reaction, affording calculated reaction energetics in stronger agreement with experiment. The foundations for the predictive application of this model to identify novel electron donors have been laid. Synthetic routes towards novel electron donor precursors have been identified for future work on this research.
6
Tyree, William Stuart. "Correlation of Structure and Magnetic Properties in Charge-Transfer Salt Molecular Magnets Composed of Decamethylmetallocene Electron Donors and Organic Electron Acceptors". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34436.
Abstract (sommario):
Di-n-propyl dicyanofumarate (DnPrDCF) and di-isopropyl dicyanofumarate (DiPrDCF) have been used as one-electron acceptors in the synthesis of charge-transfer salt magnets with decamethylmetallocenes, MCp*2 (M = Mn, Cr). Salts of each acceptor with each metallocene have been characterized and the structures of the chromium analogues have been solved. The two acceptors are structurally similar to dimethyl dicyanofumarate (DMeDCF) and diethyl dicyanofumarate (DEtDCF), which have been previously studied and found to form charge-transfer salt magnets with the aforementioned decamethylmetallocenes. A typical structural motif is present in these types of charge-transfer salts which allows for the comparison of magnetic properties based on the length or size of the alkyl group of the dialkyl dicyanofumarate. Some trends were established based on the magnetic properties of the homologous series including ordering temperature/bulkiness of the alkyl group and intrastack distances/theta values. Correlation of magnetic and structural properties may give some insight into "through-space" magnetic coupling, of which little is understood.Master of Science
7
Xu, Yunhua. "Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems". Doctoral thesis, Stockholm : Department of Organic Chemistry, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-411.
8
Zhao, Yuxi. "Synthèse de donneurs d’électrons organiques : application en synthèse organique et chimie des polymères". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0156.
Abstract (sommario):
Les donneurs d'électrons organiques (DEO), aux potentiels redox exceptionnellement négatifs, ont montré un intérêt particulier en synthèse organique du fait de leurs fortes propriétés réductrices. Ils sont capables de transférer spontanément un ou deux électrons à des substrats organiques, formant ainsi des intermédiaires radicalaires ou anioniques. Néanmoins, la diversité structurale des DEO est limitée et leur champ d'application assez restreint.Dans cette thèse, nous avons tout d'abord développé de nouvelles bibliothèques de DEO afin d'identifier de nouvelles familles de réducteurs organiques, d'élargir la gamme de potentiels redox et d'accéder à de nouvelles réactivités. Des modulations structurales appropriées sur sept catégories de sels d'iminium ont donné accès à de puissants DEO avec diverses capacités réductrices. Cette étude a également permis de rationaliser les facteurs régissant le transfert d’un ou deux électrons en fonction de la structure du DEO et des conditions réactionnelles. Une enquête mécanistique plus approfondie a confirmé les structures des espèces donneuses d'électrons formellement actives. Enfin, les DEO se sont également avérés être de remarquables systèmes redox organiques pour l’amorçage de réactions de polymérisation radicalaire et anionique. Alors que la propagation anionique est initiée par réduction directe du monomère, la simple addition d'un oxydant compétitif, avec un potentiel de réduction plus élevé, permet de passer à un processus de propagation radicalaire. Ces stratégies de polymérisation ont montré une excellente applicabilité pour la préparation d'une large gamme de (co-)polymères à haute valeur ajoutéeOrganic electron donors (OEDs) with exceptionally negative redox potentials have attracted considerable attention in organic synthesis as powerful reducers. They enable the spontaneous transfer of one or two electrons to organic substrates, to form radical or anionic intermediates. Nevertheless, the structural diversity of OEDs is limited and their application scope quite narrow. In this thesis, we first developed novel libraries of OEDs in order to identify new families of organic reducers, broaden the range of redox potentials and access new reducing reactivities. Appropriate structural modulations on seven categories of iminium salts gave access to powerful OED with various reducing abilities. It also allowed to rationalize the factors governing single- or double-electron transfers according to the OED structures and the reaction conditions. A more thorough mechanistic investigation was conducted to formally confirm the active electron donor species at work.Finally, OEDs also appeared to be remarkable organic redox initiating systems for both free radical and anionic polymerization reactions. While the anionic propagation was promoted by direct reduction of the monomer, simple addition of a competing oxidant with a higher reduction potential allowed to switch to a clean free radical propagation process. Scope investigation exhibited excellent applicability of these self-initiating polymerization strategies, which enabled the preparation of a large array of (co-)polymers with high added values
9
Fall, Arona. "Donneurs d’électrons organiques : développement d’un nouveau système catalytique photoredox". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0607.
Abstract (sommario):
Durant ces dernières décennies, la réactivité des donneurs d’électrons organiques de type énamine (DEO) a été largement exploitée dans des réactions de réduction par transfert électronique. De part leurs forts pouvoir réducteur avec des potentiels redox exceptionellement négatifs, les DEOs sont capables de transférer spontanément un ou deux électrons à des substrats organiques, formant ainsi des intermédiaires radicalaires ou anioniques. Cependant, ces DEOs sont toujours utilisés en quantité stœchiométrique, ce qui limite leur compétivité face aux catalyseurs organométalliques et organiques.Les travaux de cette thèse consistent à répondre à cette problématique en développant un nouveau système catalytique avec ces DEOs. Pour cela, plusieurs stratégies ont été envisagées. Dans une première méthode, une quantité catalytique du DEO serait utilisée pour amorcer le transfert d’électron pour la réduction du substrat. L’oxydation d’intermédiaires radicalaires générés, permettrait alors de régénérer le DEO. Cette stratégie n’a malheureusement pas donné de résultat. Une seconde méthode consisterait à régénérer le DEO à partir de la forme oxydée DEO2+, stable à l’air et d’un donneur d’électron sacrificiel (amine tertiaire, dithionite de sodium ou Rongalite®) sous photoactivation. Plusieurs étapes d’optimisation ont permis d’aboutir à un système catalytique photoredox efficace avec la forme oxydée comme photocatalyseur et la Rongalite® en tant que donneur sacrificiel. Ce nouveau système catalytique photoredox a été appliqué à la réduction de divers groupements fonctionnels (sulfone, halogénure d’aryle, triflate) par transfert mono et biélectroniqueDuring this last decade, the reactivity of enamine-based organic electron donor (OED) has been widely explored in electron transfer processes. With exceptionally negative redox potentials, OEDs spontaneously promote single (SET) or double electron transfer (DET) to an organic substrate, to form radical or anionic intermediates. However, the use of stoichiometric amount of OEDs limits their competitivity compared to their organometallic and organic catalysts. This thesis project consisted in developing a new catalytic system with OEDs. Different strategies were envisaged. In a first method a catalytic amount of OED would initiate the electron transfer to reduce the substrate. The oxidation of the generated radical intermediate would allow the regeneration of OED. Unfortunately, this strategy was unsuccessful. The second strategy would consist in regenerating the OED from its air-stable oxidized form OED2+ and a sacrificial electron donor (tertiary amine, sodium dithionite or Rongalite®) under photoactivation. Several optimizing steps allowed the development of a new efficient catalytic photoredox system with the oxidized form as photocatalyst and Rongalite® as sacrificial electron donor. This new photoredox catalytic system was applied to the reduction of various functionals groups (sulfone, aryl halide and triflate) by single electron transfer (SET) and double electron transfer (DET). The reactivity of the photocatalytic system was also explored in radical addition reactions
10
Turek, Amanda Katherine. "Activation of Electron-Deficient Quinones Through Hydrogen-Bond-Donor-Coupled Electron Transfer". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845499.
Abstract (sommario):
Quinones are organic oxidants that play important roles in biological contexts and find wide application in organic synthesis. They are known to be activated toward electron transfer through hydrogen bonding, which has largely been observed for Lewis basic, weakly oxidizing quinones. Comparable activation through H-bonding is more difficult to achieve when more reactive, electron-deficient quinones are used, as these intrinsically weaker Lewis bases are less prone to engage in H-bonding interactions.
Herein, we describe the successful application of HBD-coupled electron transfer as a strategy to activate electron-deficient quinones. A systematic investigation of several small-molecule HBDs allowed examination of the effects of H-bonding on electron transfer to o-chloranil, an electron-deficient quinone that lacks the intrinsic reactivity necessary to oxidize many organic substrates of synthetic interest. This study has led to the discovery that dicationic HBDs have an exceptionally large effect on the rate and thermodynamics of these electron transfer reactions.
Favorable modulation of the thermodynamics occurs as a result of the stabilization provided to the reduced quinone (Q•–) by the HBD. Electrochemical experiments have allowed quantification of the binding affinity for Q•– to each of the HBDs, as well as elucidation of the binding stoichiometry of the resulting ground-state complex. Monocationic HBDs bind to Q•– with 2:1 stoichiometry, whereas dicationic HBDs bind in a 1:1 complex. Dicationic bis-amidinium salts exhibit significantly improved binding to Q•–, offering more thermodynamic stabilization to this reduced state.
The effects of HBDs on the kinetics of electron transfer have also been evaluated under homogenous conditions. Reactions between o-chloranil and ferrocene derivatives exhibit pronounced HBD-dependent rate enhancements, with dicationic HBDs displaying the greatest effect. Relative to neutral dual HBDs, the bis-amidinium salts accelerate the rate of electron transfer by > 1012. Binding stoichiometries within the rate-limiting transition states corroborate the results determined electrochemically, and binding affinity correlates with rate enhancement was observed across the series of HBDs evaluated.
Application of HBD-coupled electron transfer in an oxidative lactonization illustrates that this strategy is applicable to catalysis of organic reactions. A dicationic HBD catalyst affords the lactone product in nearly quantitative yield within 24 h, whereas o-chloranil alone was ineffective (< 5% yield). The rates of lactonization with several HBD catalysts correlate well with the thermodynamic and kinetic trends described above. This trend indicates that the rate of the oxidative lactonization is related to the ability of the HBD to promote an electron transfer step. Potential strategies for application in enantioselective transformations and possibilities for future mechanistic investigation are presented.Chemistry and Chemical Biology
11
Tsutsumi, Jun'ya. "Solid-state structures and electronic properties of organic molecules fabricated by connecting electron donor and acceptor components". 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124380.
12
Lay, Alexander Kit. "New π-electron donor systems based on 1,4-dithin derivatives". Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4725/.
Abstract (sommario):
A review of organic, π-electron donor molecules is given. The focus is on non- tetrathiafulvalene based systems. Polycyclic arenes, thioalkyl substituted arenes, chalcogenated fulvalenes, peri-dichalcogen bridged polycyclic arenes and heteroarenes are covered. Various π-electron donor molecules based on acenaphtho[ 1,2-b][ 1,4]-dithin have been synthesised via various methodologies. The redox properties of these molecules, as studied by cyclic voltammetry, provide evidence that these species are efficient π-electron donors. A selection of these compounds have also been studied by Electron Spin Resonance. Two ring expansion methodologies have been utilised in the synthesis of acenaphtho[l,2-b][l,4]-dithin based systems from 1,2-dithiols. Complexation of 7,12- dithia-benzo[k]fluoranthene, thus synthesised, with 2,5-dibromo-7,7,8,8-tetracyano-p- quinodimethane and iodine (I(_4) counter ion) yielded highly crystalline but poorly conducting salts.1,2-Dibromoacenaphthylene and benzo-l,2-dithiolate species have been reacted to form new 7,12-dithia-benzo[k]fluoranthene derivatives, two of which have been studied by X-ray diffraction. The versatile oligo(l,3-dithiole-2,4,5-trithione) compound has been used to generate various compounds containing the 1,4-dithiin ring including 8,9- di(methylsulfanyl)acenaphthyleno[l,2-b][l,4]dithine, which forms complexes with 7, 7,8,8-tetracyano-p-quinodimethane, 2,5-dibromo-7,7,8,8-tetracyano-p-quinodimethane and iodine (I(_7) counter ion) all three of which have been studied by X-ray diffraction. A novel 1,2,4-trithiolane has also been synthesised and characterised by X-ray diffraction.
13
Bröker, Benjamin. "Electronic and structural properties of interfaces between electron donor & acceptor molecules and conductive electrodes". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16257.
Abstract (sommario):
Die vorliegende Arbeit behandelt Fragestellungen aus der Organischen Elektronik, in der die Ladungsträgerinjektion in alle Arten von Bauteilen kritisch von der elektronischen und morphologischen Struktur der Grenzflächen zwischen Elektrode und den konjugierten organischen Molekülen (KOM) abhängt. Näher betrachtet wurden: die Energieniveauanpassung mit starken (i) Elektronendonatoren und (ii) -akzeptoren und (iii) die dichteabhängige Umorientierung einer molekularen Monolage. Zur Analyse wurden Photoelektronen- und Reflektionsabsorptionsinfrarotspektroskopie angewandt. Weitere Informationen konnten durch Modellierung mit Dichtefunktionaltheory gewonnen werden, die über Kollaborationen zur Verfügung standen. (i) Das Konzept der optimierten Energieniveauanpassung mit starken Elektronenakzeptoren konnte auf Donatoren erweitert und damit erfolgreich von der Anode zur Kathode transferiert werden. Auch hier führte der Ladungstransfer zu einem Dipol über die Grenzfläche, womit die Austrittsarbeit um bis zu 2.2 eV reduziert wurde. Als Resultat konnte die Elektroneninjektionsbarriere in nachfolgende Materialien entscheidend verringert werden (bis zu 0.8 eV). (ii) Ein bis dato unerforschter starker Elektronenaktzeptor [hexaaza-triphenylene-hexacarbonitrile (HATCN)] wurde vollständig verschiedenen Elektroden charakterisiert. HATCN zeigte dabei eine bessere Performance verglichen mit derzeit üblichen Materialien (starke Austrittsarbeitsanhebung und Verringerung der Lochinjektionsbarriere um bis zu 1.0 eV). (iii) Zusätzlich konnte mit HATCN gezeigt werden, dass eine liegende molekulare Monolage durch Erhöhung der Moleküldichte in eine stehende Monolage umgewandelt werden kann. Dies führte zu einer Änderung der chemischen Bindung zum Metall und damit zu einer starken Modifikation der elektronischen Struktur der Grenzfläche. Die vorliegende Arbeit liefert damit wertvolle Informationen für das Verständnis der Grenzfläche zwischen Elektrode und KOM in der Organischen Elektronik.The present work is embedded in the field of organic electronics, where charge injection into devices is critically determined by the electronic and structural properties of the interfaces between the electrodes and the conjugated organic materials (COMs). Three main topics are addressed: energy level tuning with new and strong electron (i) donor and (ii) acceptor materials and (iii) the density dependent re-orientation of a molecular monolayer and its impact on the energy level alignment. To study these topics photoelectron and reflection absorption infrared spectroscopy were used. Moreover, additional information was obtained from density functional theory modelling, which was available through collaboration. (i) A concept of optimizing the energy level alignment at interfaces with strong molecular acceptors was extended to donor materials and thus successfully transferred from the anode to the cathode side of the device. Also in this case, charge transfer leads to a chemisorbed molecular monolayer. Due to the dipole across the interface, the work function of the electrode is reduced by up to 2.2 eV. Consequently, a reduced electron injection barrier into subsequently deposited materials is achieved (up to 0.8 eV). (ii) A yet unexplored strong electron acceptor material [i.e. hexaazatriphenylene- hexacarbonitrile (HATCN)] is thoroughly investigated on various surfaces. HATCN shows superior performance as electron acceptor material compared to presently used materials (e.g. work function modification and hole injection barrier reduction by up to 1 eV). (iii) Also with HATCN, the orientation of a molecular monolayer is observed to change from a face-on to an edge-on depending on layer density. This is accompanied by a re-hybridization of molecular and metal electronic states, which significantly modifies the interface electronic properties. All findings presented are valuable for the understanding of electrode-COM interfaces in organic electronics.
14
Doni, Eswararao. "Novel applications of a 4-DMAP-derived organic electron donor under photoactivation". Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=19078.
15
Caulfield, Jason M. "Magnetic quantum oscillations in organic metals based on the molecule bis(ethylenedithio)tetrathiafulvalene". Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:5fbf2599-96d8-4eac-b882-ac74213ac3a5.
Abstract (sommario):
ET charge transfer salts (where ET is
16
Christodoulou, Christodoulos. "Electronic and structural properties at the interfaces between graphene and molecular acceptors/donors". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17318.
Abstract (sommario):
In dieser Arbeit wurde die Austrittsarbeit von Graphen, einer vielversprechenden Elektrodenmaterial für (opto)- elektronische Bauteile, durch die Adsorption von luftbeständigen konjugierten organischen Molekülen (KOMs), welche als Akzeptoren und Donatoren fungieren, modifiziert. Die Eigenschaften der Valenz- und Rumpfniveaus sowie die Austrittsarbeitsmodifikation der vakuumverdampften KOMs wurden mit Photoelektronenspektroskopie (PES) untersucht, während die Orientierung der KOMs mit Röntgen-Nahkanten-Absorptions-Spektroskopie (NEXAFS) aufgeklärt wurde. Die Austrittsarbeit von Graphen auf Quartz (G/Qu) lässt sich auf maximal 5.7 eV und minimal 3 eV anpassen, welches aus einem Ladungstransfer direkt an der Grenzfläche resultiert, der keine Ausbildung von kovalenten Bindungen zwischen der molekularen Monolage und dem Graphen beinhaltet. Zudem, für den starken molekularen Akzeptor Hexaazatriphenylen-Hexacarbonitril (HATCN) verläuft die Austrittsarbeitserhöhung über eine Orientierungsänderung der Moleküle im Monolagenbereich. Für alle anderen auf G/Qu abgeschiedenen Akzeptoren (Donatoren) wurde beobachtet, dass der Ladungstransfer eine positive (negative) Oberflächen-ladungsdotierung der Graphen-Schicht bewirkt, welches in einer Austrittsarbeitserhöhung (-erniedrigung) resultiert. Letztere ließ sich jeweils in zwei Beiträge zerlegen: (a) Verschiebung des Vakuumniveaus durch einen Grenzflächendipol an der KOM/Graphen-Grenzfläche und (b) Verschiebung des Fermi-Niveaus durch Oberflächenladungstransferdotierung der Graphen-Schicht. Weiterhin wurde der molekulare Akzeptor Hexafluoro-tetracyano napththoquinodimethan (F6TCNNQ) sowohl auf G/Qu als auch auf Graphen auf Kupfer abgeschieden, wobei sich herausstellte, dass der Ladungstransfer im ersteren Fall vom Graphen stammt, und im letzteren von der Kupferunterlage. Die Ergebnisse werden von Dichtefunktionaltheorieberechnungen gestützt und tragen erheblich zum Verständnis von Graphen/KOM-Grenzflächen bei.In this thesis, the work function of graphene, a promising electrode for (opto)electronic devices was modified by adsorption of air-stable conjugated organic molecules (COMs) that act as strong molecular acceptors or donors. The valence and core level properties, together with the work function modification of the vacuum-deposited COMs on graphene were investigated with photoelectron spectroscopy (PES), while the orientation of COMs was studied with near edge X-ray fine structure spectroscopy (NEXAFS). The work function of graphene-on-quartz (G/Qu) is modified up to 5.7 eV and down to 3 eV as a result of charge transfer (CT) occurring right at the interface, which does not invoke covalent bond formation between the molecular monolayer and the graphene. In addition to the CT, in the case of the molecular acceptor hexaazatriphenylene-hexacarbonitrile (HATCN), the work function increase proceeded via a density-dependent re-orientation of the molecule in the monolayer regime. For all the other tested molecular acceptors (donors) deposited on graphene-on-quartz, the CT was observed to induce positive (negative) surface CT doping of the graphene layer, leading to a work function increase (decrease) and was disentangled into two contributions: (a) shift of the Vacuum level due to the formation of an interface dipole at the COM/graphene interface and (b) shift of the Fermi level of the graphene due to the surface CT doping. Additionally, the molecular acceptor hexafluoro-tetracyanonapththoquinodimethane (F6TCNNQ) was deposited on both G/Qu and graphene-on-copper, where the CT was found to originate from graphene and copper support respectively. The findings were supported by density functional theory calculations and significantly add to a fundamental understanding of graphene/COM interfaces.
17
ZHOU, JIANING. "DIKETOPYRROLOPYRROLE‐ AND ISOINDIGO‐ BASED CONJUGATED POLYMER FOR ORGANIC ELECTRONIC DEVICE". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619617910133478.
18
Richard, Coralie Adèle. "Tailoring benzodithiophene core molecules for organic electronic applications". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53419.
Abstract (sommario):
In this dissertation, the multiple facets of benzodithiophene (BDT) units are explored, with a focus on understanding how the isomerism of the BDT structure affects the macroscopic properties of the oligomeric and polymeric materials created. First, the story focuses on an overview of the BDT synthons and their applications in organic electronics. A straightforward synthesis of BDT and its derivatization to seven π-conjugated building blocks and seven polymers is presented. Then, symmetric (donor)2-acceptor (D2-A) dye architecture for application in dye-sensitized solar cells are investigated. Two isomeric systems are studied, and the branched sensitizers show a greater incident photon-to-current efficiency than the linear dyes. The nature of the accepting core is also varied between dibenzophenazine to dithienophenazine. The sensitizer with the weakest accepting core displays the best photovoltaic performance, due to an increase in the open-circuit voltage of ~100 mV caused by the favorable shift of the metal oxide conduction band. Lastly, a study of the donating building blocks in these (D2-A) sensitizers demonstrates that increasing the number of donor units from two to six thiophene moiety doubles the solar cell performance, due to the improvement of the light harvesting ability.
19
Placencia, Diogenes. "Interface Studies of Small-Molecule Organic Photovoltaics; Surface Modifications, Electron Donor Texturing, and Co-Facial Variations at the Donor/Acceptor Heterojunctions". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202936.
Abstract (sommario):
The role of the oxide/organic and organic/organic interfaces in small-molecule planar-Heterojunction (PHJ) photovoltaics was investigated with three interrelated projects: i) indium-tin oxide (ITO) bottom contact electrodes were modified with gold nanoparticles (Au-NPs) to improve rates of charge-transfer at the donor/oxide interface, ii) donor layers in OPVs were textured to increase charge generation at the organic/organic' interface, and iii) the effect of co-facial overlap on device performance via tuning of the electron acceptor orientation at the organic/organic interface. The modification of ITO with Au-NPs showed increased performance in small-molecule OPVs when compared to non-processed ITO devices due to the interactions between the Au-NPs and the donor material. Textured TiOPc increased overall device performance by a factor of 2X via the increased surface area, near-IR absorption, and increased mobilities. Modified and un-modified PTCDA acceptors showed that co-facial overlap at the organic/organic' interface is a large determinant in device performance, while the performance in small-molecule planar-heterojunction photovoltaics were severely affected by the pre-treatment process, most likely due to the particular interactions between the oxide and the donor material.
20
Webre, Whitney Ann. "Spectral, Electrochemical, Electron Transfer, and Photoelectrochemical Studies of Tetrapyrrole Derived Supramolecular Systems". Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609091/.
Abstract (sommario):
Energy- and electron-transfer processes in molecular and supramolecular donor-acceptor systems are of current interest in order to develop light-energy harvesting systems through designing covalently linked donor-acceptor systems or utilizing self-assembled donor-acceptor systems. The research presented in this dissertation deals with the electrochemical, anion binding, and photochemical studies of various oxoporphyrinogen (OxPs), porphyrin, corrole, and phenothiazine systems. The first chapter provides a brief introduction to the material discussed in the subsequent chapters. The second chapter discusses the bromination of meso-tetraarylporphyrings and how that affects their electrochemical, catalytic, and other properties. Bromination of these porphyrins and oxoporphyrinogens allow the HOMO-LUMO gap to increase revealing blue-shifted absorption. Brominated OxPs and bis-crown ether OxP self-assembled with anions depending on strength of the anion and size of the binding site. The addition of crown ethers allows a cation binding site which makes a self-assembled donor-acceptor supramolecular system.Chapters 5 and 6 discuss a series of donor-acceptor conjugates based on zinc porphyrin as the electron donor and copper(III) corrole as the electron acceptor. These studies illustrate the importance of copper(III) corrole as a potent electron acceptor for the construction of energy harvesting model compounds, and constitute the first definitive proof of charge separation in ZnP-CuIIIC systems.Chapter 7 summarizes several interesting observations made in the present study on DSSCs built on two types of phenothiazine dyes having one or two cyanocinnamic acid groups.
21
Pandey, Laxman. "Theoretical studies of the structure-property relationships of hole- and electron-transport materials for organic photovoltaic applications". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48964.
Abstract (sommario):
Donor-acceptor and thiophene based π-conjugated molecules and polymers, along with fullerene derivatives, are extensively used active components in the photoactive layer of organic photovoltaic devices. In this dissertation, we make use of several computational methodologies to investigate structure-property relationships of these organic systems in their molecular forms. We begin with an overview of the field of organic photovoltaics and some of the important problems in organic solar cells that are currently being investigated. This is then followed by a brief review of the electronic-structure methods (e.g. Hartree-Fock theory, Density Functional Theory, and Time-dependent Density Functional Theory) that are employed.
We then present the main results of the dissertation. Chapter 3 provides a broad overview on how changes to the donor-acceptor copolymer chemical structure impacts its intrinsic geometric, electronic, and optical properties. Chapter 4 focuses on the characterization of the lowest excited-states and optical absorption spectra in donor-acceptor copolymers. In Chapter 5, we investigate the effects of alkyl side-chain placements in the π-conjugated backbone of oligothiophenes and how that impacts their intramolecular properties as well as the oligomer:fullerene interfacial interactions. Chapter 6 presents our investigation on the role of oligomer:fullerene configuration and reorganization energy on exciton-dissociation and charge-recombination processes. Finally, a synopsis of the work and further considerations are presented in Chapter 7.
22
Chan, Yiu Him. "Effect of dopants and gate dielectrics on charge transport and performance of organic thin film transistor". HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1450.
23
Peckus, D., A. Devizis, D. Hertel e V. Gulbinas. "Excited State Relaxation in Vacuum Deposited and Solution Processed Films of Merocyanine/Fulerene Blends". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35299.
Abstract (sommario):
Exciton dynamics in merocyanine/fulerene blend films made by vacuum deposition and solution processing
techniques were investigated by means of steady-state and time resolved fluorescence and
absorption spectroscopy. Intermolecular charge transfer states are formed during several ps in neat
merocianine films, which determine their fluorescence properties. Fullerene additives cause formation of
new heterogeneous charge transfer states. Even a small fullerene concentration significantly influences
the exciton dynamics by quenching inherent merocianine fluorescent states and causing appearance of new
fluorescence bands caused by the charge transfer states between merocyanine and fullerene molecules. All
fluorescence bands are quenched in films with high fulerence concentration due to the charge carrier generation,
and the quenching effect is stronger in vacuum deposited films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35299
24
Svarovsky, Serge A. "Structure, stability and reactivity of small organic sulfinic and sulfonic acids toxicological implications ; Role of charge transfer complexes in oxidation cleavage of benzpinacols by iron (III) trispenanthroline /". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1231.
25
Schubert, Marcel. "Elementary processes in layers of electron transporting Donor-acceptor copolymers : investigation of charge transport and application to organic solar cells". Phd thesis, Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7079/.
Abstract (sommario):
Donor-acceptor (D-A) copolymers have revolutionized the field of organic electronics over the last decade. Comprised of a electron rich and an electron deficient molecular unit, these copolymers facilitate the systematic modification of the material's optoelectronic properties. The ability to tune the optical band gap and to optimize the molecular frontier orbitals as well as the manifold of structural sites that enable chemical modifications has created a tremendous variety of copolymer structures. Today, these materials reach or even exceed the performance of amorphous inorganic semiconductors. Most impressively, the charge carrier mobility of D-A copolymers has been pushed to the technologically important value of 10 cm^{2}V^{-1}s^{-1}. Furthermore, owed to their enormous variability they are the material of choice for the donor component in organic solar cells, which have recently surpassed the efficiency threshold of 10%.
Because of the great number of available D-A copolymers and due to their fast chemical evolution, there is a significant lack of understanding of the fundamental physical properties of these materials. Furthermore, the complex chemical and electronic structure of D-A copolymers in combination with their semi-crystalline morphology impede a straightforward identification of the microscopic origin of their superior performance. In this thesis, two aspects of prototype D-A copolymers were analysed. These are the investigation of electron transport in several copolymers and the application of low band gap copolymers as acceptor component in organic solar cells.
In the first part, the investigation of a series of chemically modified fluorene-based copolymers is presented. The charge carrier mobility varies strongly between the different derivatives, although only moderate structural changes on the copolymers structure were made. Furthermore, rather unusual photocurrent transients were observed for one of the copolymers. Numerical simulations of the experimental results reveal that this behavior arises from a severe trapping of electrons in an exponential distribution of trap states. Based on the comparison of simulation and experiment, the general impact of charge carrier trapping on the shape of photo-CELIV and time-of-flight transients is discussed.
In addition, the high performance naphthalenediimide (NDI)-based copolymer P(NDI2OD-T2) was characterized. It is shown that the copolymer posses one of the highest electron mobilities reported so far, which makes it attractive to be used as the electron accepting component in organic photovoltaic cells.par
Solar cells were prepared from two NDI-containing copolymers, blended with the hole transporting polymer P3HT. I demonstrate that the use of appropriate, high boiling point solvents can significantly increase the power conversion efficiency of these devices. Spectroscopic studies reveal that the pre-aggregation of the copolymers is suppressed in these solvents, which has a strong impact on the blend morphology.
Finally, a systematic study of P3HT:P(NDI2OD-T2) blends is presented, which quantifies the processes that limit the efficiency of devices. The major loss channel for excited states was determined by transient and steady state spectroscopic investigations: the majority of initially generated electron-hole pairs is annihilated by an ultrafast geminate recombination process. Furthermore, exciton self-trapping in P(NDI2OD-T2) domains account for an additional reduction of the efficiency. The correlation of the photocurrent to microscopic morphology parameters was used to disclose the factors that limit the charge generation efficiency. Our results suggest that the orientation of the donor and acceptor crystallites relative to each other represents the main factor that determines the free charge carrier yield in this material system. This provides an explanation for the overall low efficiencies that are generally observed in all-polymer solar cells.Donator-Akzeptor (D-A) Copolymere haben das Feld der organischen Elektronik revolutioniert. Bestehend aus einer elektronen-reichen und einer elektronen-armen molekularen Einheit,ermöglichen diese Polymere die systematische Anpassung ihrer optischen und elektronischen Eigenschaften. Zu diesen zählen insbesondere die optische Bandlücke und die Lage der Energiezustände. Dabei lassen sie sich sehr vielseitig chemisch modifizieren, was zu einer imensen Anzahl an unterschiedlichen Polymerstrukturen geführt hat. Dies hat entscheidend dazu beigetragen, dass D-A-Copolymere heute in Bezug auf ihren Ladungstransport die Effizienz von anorganischen Halbleitern erreichen oder bereits übetreffen. Des Weiteren lassen sich diese Materialien auch hervorragend in Organischen Solarzellen verwenden, welche jüngst eine Effizienz von über 10% überschritten haben. Als Folge der beträchtlichen Anzahl an unterschiedlichen D-A-Copolymeren konnte das physikalische Verständnis ihrer Eigenschaften bisher nicht mit dieser rasanten Entwicklung Schritt halten. Dies liegt nicht zuletzt an der komplexen chemischen und mikroskopischen Struktur im Film, in welchem die Polymere in einem teil-kristallinen Zustand vorliegen. Um ein besseres Verständnis der grundlegenden Funktionsweise zu erlangen, habe ich in meiner Arbeit sowohl den Ladungstransport als auch die photovoltaischen Eigenschaften einer Reihe von prototypischen, elektronen-transportierenden D-A Copolymeren beleuchtet. Im ersten Teil wurden Copolymere mit geringfügigen chemischen Variationen untersucht. Diese Variationen führen zu einer starken Änderung des Ladungstransportverhaltens. Besonders auffällig waren hier die Ergebnisse eines Polymers, welches sehr ungewöhnliche transiente Strom-Charakteristiken zeigte. Die nähere Untersuchung ergab, dass in diesem Material elektrisch aktive Fallenzustände existieren. Dieser Effekt wurde dann benutzt um den Einfluss solcher Fallen auf transiente Messung im Allgemeinen zu beschreiben. Zusätzlich wurde der Elektronentransport in einem neuartigen Copolymer untersucht, welche die bis dato größte gemesse Elektronenmobilität für konjugierte Polymere zeigte. Darauf basierend wurde versucht, die neuartigen Copolymere als Akzeptoren in Organischen Solarzellen zu implementieren. Die Optimierung dieser Zellen erwies sich jedoch als schwierig, konnte aber erreicht werden, indem die Lösungseigenschaften der Copolymere untersucht und systematisch gesteuert wurden. Im Weiteren werden umfangreiche Untersuchungen zu den relevanten Verlustprozessen gezeigt. Besonders hervorzuheben ist hier die Beobachtung, dass hohe Effizienzen nur bei einer coplanaren Packung der Donator/Akzeptor-Kristalle erreicht werden können. Diese Struktureigenschaft wird hier zum ersten Mal beschrieben und stellt einen wichtigen Erkenntnisgewinn zum Verständnis von Polymersolarzellen dar.
26
Fu, Boyi. "Design and syntheses of hole and electron transport donor-acceptor polymeric semiconductors and their applications to organic field-effect transistors". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54868.
Abstract (sommario):
The π-conjugated organic and polymeric semiconducting materials have attracted much attention in the past years due to their significant potential in applications to electronic and optoelectronic devices including organic field-effect transistors (OFETs), organic photovoltaics (OPVs), and organic light-emitting diodes (OLEDs), etc. Yet, organic and polymeric semiconductors still have challenges associated with their relatively low charge carrier (hole and electron) transport mobilities and ambient stability in OFET applications.
This dissertation discusses the molecular engineering on backbones and side-chains of π-conjugated semiconducting polymers to enhance the hole and electron field-effect mobilities. Three donor-acceptor copolymers, the hole transport (p-type) poly(hexathiophene-co-benzo- thiazole) (PBT6), the hole transport poly(thiophenes-benzothiadiazole-thiophenes-diketopyrrolo- pyrrole) (pTBTD), and the electron transport (n-type) poly(dithieno-diketopyrrolopyrrole-bithiazole) (PDBTz) have been developed. Besides, the effect of polymer side chains on polymer solution-processability and charge carrier transport properties was systematically investigated: a side chain 5-decylheptadecyl having the branching position remote from the polymer backbone merges the advantages of the improved solubility from traditional branched side chains in which the branch chains are close to polymer backbone and the effective π-π intermolecular interactions commonly associated with linear side chains. This indicates the potential of side chain engineering to facilitate the charge carrier transport performance of organic and polymeric semiconductors. Additionally, PDBTz solution-processing to OFETs based on non-halogenated solvents (xylenes and tetralin) was studied. The resultant thin-film OFET devices based on non-halogenated solvents exhibited similar film morphology and field-effect electron mobilities as the counterparts based on halogenated solvents, indicative of the feasibility of developing high mobility OFET devices through more environmentally-benign processing.
27
Biswas, Debanjan. "A Modified Procedure for the Synthesis of Bis(phenylenedioxy)tetrathiafulvalene (BPDO-TTF): an Electron Donor for Charge Transfer Organic Complexes". [Johnson City, Tenn. : East Tennessee State University], 2002. http://etd-submit.etsu.edu/etd/theses/available/etd-0710102-123535/restricted/BixwasD073102.pdf.
28
GALLONI, PIERLUCA. "Construction of electron-active complex systems as model for artificial photosynthesis". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2004. http://hdl.handle.net/2108/202905.
Abstract (sommario):
La fotosintesi artificiale è un obiettivo ambizioso per la scienza moderna, che richiede una comprensione completa dei sistemi naturali. La comprensione di tutte le diverse reazioni del sistema è uno degli aspetti fondamentali nella ricerca chimica, fisica e biologica. Lo studio delle reazioni di trasferimento elettronico tra un accettore e un donatore è un punto cruciale, sia per lo sviluppo di sistemi artificiali sintetici, sia per possibili applicazioni nella costruzione di dispositivi elettronici e materiali fotosensibili. Lo scopo di questa tesi è stato quello di investigare reazioni di trasferimento elettronico e di energia, per avere informazioni riguardo le leggi che regolano questi sistemi complessi, usando diversi sistemi donatore-accettore, tra i quali particolare attenzione è stata rivolta al C60 come accettore e al ferrocene come donatore. Il lavoro sintetico è stato una parte importante della tesi, richiedendo tempo per ottimizzare le condizioni di reazione, le procedure di purificazione e per la completa caratterizzazione dei prodotti. Numerosi nuovi composti sono stati sintetizzati e sono state migliorate le rese per alcuni prodotti noti da letteratura. Un aspetto importante del lavoro ha riguardato lo studio dell’interazione tra donatore e l’accettore in alcune delle diadi ottenute, sia allo stato fondamentale, sia nello stato eccitato. Tra i vari risultati, i più interssanti possono essere riassunti nei seguenti punti. a) Un andamento peculiare emerge dagli esperimenti fotofisici e computazionali e dalle misure elettrochimiche e degli spettri di assorbimento nelle diadi fluorene-fullerene: cambia l’interazione, cambiando la posizione del fluorene che lega il fullerene. b) Risultati molto interessanti sono stati ottenuti quando ferrocene e fullerene sono uniti tramite legame spiro, dando una diade dalla geometria rigida. Difatti, confrontando le proprietà nello stato eccitato di questa diade con quelle della N-metil-2-ferrocenil-[3,4]-fulleropirrolidina, con maggiore libertà conformazionale, è stata osservata una reazione di trasferimento elettronico più veloce, indice di una maggiore interazione tra i due componenti. c) In diadi supramolecolari composte da ZnSalen e N-metil-2-piridil-[3,4]-fulleropirrolidina è stato osservato un efficiente trasferimento di energia. Questo sistema può essere usato come modello nei sistemi impiegati nella cattura della luce. d) Un efficiente trasferimento di elettroni avviene tra la tetraferrocenilporfirina di zinco e la N-metil-2piridil-[3,4]-fulleropirrolidina in una diade supramolecolare, come è stato osservato tramite la spettroscopia transiente, dove un tempo di vita di 800 ps della specie eccitata a separazione di carica è stato ottenuto in un solvente apolare come il toluene. In conclusione, sono stati ottenuti nuovi sistemi per lo studio delle reazioni di trasferimento di energia e di elettroni, che sono stati studiati usando diversi approcci sperimentali. I risultati possono essere di aiuto sia per una miglior comprensione dei fenomeni naturali, sia per lo sviluppo e la costruzione di dispositivi fotosensibili.Artificial photosynthesis is an ambitions target of modern science that obviously requires a complete understanding of natural photosynthesis. The understanding of all steps involved is one of the most important topic in chemical, biological, and physical research. The study of electron transfer reaction between donor and acceptor molecules is a crucial key point, both for development of artificial photosynthesis and for application in electronic devices and photosensible materials. The aim of this thesis was to investigate electron and energy transfer reactions, as source of information about the mechanisms that rule this complex reaction, using different donor-acceptor systems, among which attention have been focused at C60 as acceptor and ferrocene as donor. Synthetic work constituted a major task in this thesis, requiring several attempts in order to optimize reaction conditions, purification procedures and full characterization of products. A number of new compounds was obtained together with improved yields of known products. Another important aspect of the work involved investigation of donor-acceptor interaction in some of the dyads, both in ground and in excited states. Among all the results, the most significant ones may be summarized in the following points. a) A peculiar behaviour emerged from photophysical and computational experiments, electronic spectra and electrochemical measurements of fluorene-fullerene dyads. Different interaction was the result of changing the position through which the two moieties are connected. b) Very interesting results emerged when a frozen structure was obtained from connecting ferrocene and fullerene moieties in a rigid assembly. In fact, in comparison with a dyad with flexible connection, a faster electron transfer rate - and therefore an enhanced interaction - was observed in the excited state. c) Efficient energy transfer was observed with supramolecular (ZnSalen)-(N-methyl-2-pyridyl-[3,4]fulleropyrrolidine) dyads. This system can be used as a good model for light harvesting model. d) Very efficient electron transfer reaction occurred between zinctetraferrocenylporphyrin and pyridylfulleropyrrolidine in supramolecular (ZnFc4Porph)-(N-methyl-2-pyridyl-[3,4]-fulleropyrrolidine) dyad, as observed by transient spectroscopy, even in non polar solvent such as toluene. In conclusion, new good systems for energy an electron transfer were obtained and investigated by different approaches. They can be used to reach a deeper knowledge of complex phenomena that rule natural photosynthesis as well as to build photosensible devices.
29
Patil, Basanagouda B. "Enhancing the electrical performance of the donor-acceptor conjugated polymer based organic field effect transistors through device engineering for electronic applications". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207503/1/Basanagouda_Patil_Thesis.pdf.
Abstract (sommario):
This thesis is a step towards developing all solution processed, low operating voltage, Donor-Acceptor Conjugated Polymers based Organic Field Effect Transistors (OFETs) for printed and flexible electronics. Main emphasis has been devoted to developing series of highly tailored device engineering strategies that bring sequential improvements to electrical characteristics. Research outcomes are guided by structure-property evaluation, including semiconductor-dielectric interface engineering for optimal response, and work-function tuning with application of self-assembled monolayers to circumvent loss mechanisms. It also investigates the impact of packaging for air stable operation using Cytop as a passivation cum threshold voltage stabilizing layer in dual-gate OFET operation.
30
Schubert, Marcel [Verfasser], e Dieter [Akademischer Betreuer] Neher. "Elementary processes in layers of electron transporting Donor-acceptor copolymers : investigation of charge transport and application to organic solar cells / Marcel Schubert. Betreuer: Dieter Neher". Potsdam : Universitätsbibliothek der Universität Potsdam, 2014. http://d-nb.info/1052682847/34.
31
Ponsot, Amanda Eileen. "SYNTHESIS OF TETRABENZO[18]CYCLYNE CROSS-CONJUGATED MACROCYCLES WITH FOCUS ON THE DONOR-ACCEPTOR INDUCED FUNCTIONALITY". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280887889.
32
Maibach, Julia [Verfasser], Wolfram [Akademischer Betreuer] Jaegermann e Heinz von [Akademischer Betreuer] Seggern. "Preparation and Characterization of Solution Processed Organic Semiconductor Interfaces: Electronic Properties of Thiophene-Fullerene based Donor-Acceptor Systems / Julia Maibach. Betreuer: Wolfram Jaegermann ; Heinz von Seggern". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2014. http://d-nb.info/1110901321/34.
33
Benahmed-Gasmi, Amina. "Nouveaux précurseurs de matériaux organiques conducteurs : des donneurs-pi aux polymères conjugués". Angers, 1996. http://www.theses.fr/1996ANGE0020.
Abstract (sommario):
Ce travail porte sur l'élaboration et la caractérisation de plusieurs séries de systèmes hybrides du tetrathiafulvalène (HTTFS). Ces systèmes sont construits par le greffage de deux motifs 1,3-dithiole-2-ylidene aux deux extrémités d'un espaceur conjugué. Apres une première étape consacrée à l'analyse des différentes possibilités d'insertion d'espaceurs benzéniques, plusieurs séries de HTTFS dérivées d'hétérocycles aromatiques, thiophène, furanne et n-méthyl pyrrole, ont été synthétisées, l'analyse des propriétés électrochimiques de ces derniers montre qu'ils conduisent à un abaissement du potentiel d'oxydation avec une réduction des repulsions coulombiennes au stade dicationique. Sur la base des résultats obtenus, nous avons cherché à accroitre l'extension spatiale de ces systèmes en utilisant un oligomère conjugué. Ainsi, l'oxydation chimique et électrochimique des 2-(1,4-dithiafulven-6-yl)thiophène a permis d'accéder facilement à des analogues étendus du tetrathiafulvalène (ETTFS) symétriques. Cependant, l'augmentation du nombre d'hétérocycles s'est révélée limitée, ces résultats nous ont amenés à la synthèse de nouveaux espaceurs: dithiényl- et difurylpolyènes dont les propriétés optiques et électrochimiques révèlent que l'augmentation du nombre de doubles liaisons diminue les valeurs des potentiels d'oxydation et conduit à un déplacement bathochrome du maximum d'absorption, avec une diminution importante du gap homo-lumo. Enfin, les enseignements tirés de cette dernière phase de ce travail ont permis de définir des précurseurs dont l'électropolymérisation a conduit à de nouveaux polymères conjugues dérivés du furanne qui sont les plus conducteurs connus jusqu'à présent.
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Becher, Tiago Branco. "SÍNTESE E CARACTERIZAÇÃO DE DÍADES VISANDO A APLICAÇÃO EM DISPOSITIVOS FOTOVOLTAICOS". UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2013. http://tede2.uepg.br/jspui/handle/prefix/2110.
Abstract (sommario):
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In this paper we address the development of synthetic routes to four organic structures called dyads, which are compounds formed by an electron donating group covalently attached to an electron acceptor group. What sparked your interest in synthesizing these molecules was the potential of being applied in organic photovoltaic devices, because this type of structure has the ability of promoting a charge separation of the exciton generated after light absorption. This happens due to the proximity between the donor and acceptor species. In this work we have chosen the group derived from naphthalamide as electron donor, which has features like thermal and photochemical stabilities and conjugated double bonds, which cause the electrons p remain delocalized, facilitating the release of electrons when they receive energy. As electron acceptor it was chosen groups derived from fluorene,thiophene and benzonitrile containing both nitrile groups (strongly electron with drawing electron), which have characteristics of electron acceptors. The synthetic route of the NCT dyad was composed of two stages. In the first step of the synthesis of this dyad it was added a saturated chain of six carbon, proven by the NMR data with the appearance of the signs of the carbons of the chain in the region 1.5 to 3 ppm, so the next step was performed by the reaction of this product with the electron acceptor, the thiophene. In the synthetic route of the NCF it was performed three steps of the five motions initially, the first step being the same as performed for the preceding dyad. In the next step the objective of the reaction was the addition of iodine to fluorene derivative, which was confirmed by the appearance of bands of C-I bond in the IR spectra. The third and final stage of the dyad NCF had the goal of replacing the iodines by cyano group. The results show that this step it actually occurred mainly because of the nitrile band in the IR spectrum. The dyad NCB had only one step, in which the derivative naphthalamide was linked to the benzonitrile by a SN2 reaction, which was confirmed by NMR analysis that shows all the characteristic signs of the product formed. The dyad NT was the only one that did not have the separation between the donor and acceptor of electrons by a aliphatic carbon chain. Its synthesis aimed to connect the two reagents directly in only one step. All synthesized products were characterized by IR spectroscopy and 1H NMR, and the determination of their melting point, with these characterization it was concluded that only the dyad NCB was successfully obtained.
Neste trabalho abordamos o desenvolvimento de rotas sintéticas para quatro estruturas orgânicas chamadas díades, que são compostos formados por um grupo doador de elétrons conectado covalentemente a um grupor aceitador de elétrons. O que despertou o interesse em sintetizar estas moléculas foi o potencial de serem aplicadas em dispositivos fotovoltaicos orgânicos, pois esse tipo de estrutura tem como propriedade principal a capacidade de, após a absorção de luz, promover uma separação de carga do éxciton gerado devido à proximidade entre a espécie doadora e aceitadora de elétrons. Nesse trabalho foi escolhido o grupo derivado da naftalamida como doador de elétrons, que tem como características estabilidades térmica e fotoquímica e duplas ligações conjugadas, que fazem com que os elétrons p fiquem delocalizados, facilitando a liberação de elétrons quando estes recebem energia. Como aceitador de elétrons foram escolhidos grupos derivados do fluoreno,tiofeno e da benzonitrila ambos contendo grupos nitrilas (fortemente elétron-retirador de elétrons), os quais apresentam características aceptoras de elétrons. A rota sintética da díade NCT foi composta de duas etapas. Na primeira etapa de síntese desta díade foi adicionada uma cadeia saturada de seis carbonos, comprovada pelos dados de RMN com o surgimento dos sinais dos carbonos da cadeia na região de 1,5 a 3 ppm, para que na próxima etapa fosse realizada a reação deste produto com o aceitador de elétrons, o tiofeno. Na rota sintética da díade NCF foram realizadas três etapas das cinco propostas inicialmente, sendo a primeira etapa a mesma da realizada para a díade anterior. Na etapa seguinte o objetivo da reação foi à adição do iodo ao derivado fluoreno, a qual foi comprovada pelo surgimento das bandas da ligação C-I no espectro de IV. A terceira e última etapa da díade NCF teve o objetivo da substituir os iodos pelo grupo ciano. Os resultados desta etapa mostram que isto realmente ocorreu principalmente pelo surgimento da banda da nitrila no espectro de IV. A díade NCB teve somente uma etapa, na qual o derivado da naftalamida se uniu ao da benzonitrila por uma reação SN2, que foi confirmado pela analise de RMN que apresenta todos os sinais característicos do produto formado. A díade NT é a única que não possui a separação entre o doador e o aceitador de elétrons por uma cadeia de carbonos. Sua síntese teve como objetivo ligar os dois reagentes diretamente em somente uma etapa. Todos os produtos sintetizados foram caracterizados pelas espectroscopias de IV e de RMN de 1H,além da determinação de seu ponto de fusão, com estas análises foi concluído que somente a díade NCB foi sintentizada.
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Fournier, Jeannine. "Adsorption des hydrocarbures polycycliques aromatiques sur des solides donneurs d'electrons". Paris 6, 1987. http://www.theses.fr/1987PA066168.
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Widmer, Johannes. "Charge transport and energy levels in organic semiconductors". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-154918.
Abstract (sommario):
Organic semiconductors are a new key technology for large-area and flexible thin-film electronics. They are deposited as thin films (sub-nanometer to micrometer) on large-area substrates. The technologically most advanced applications are organic light emitting diodes (OLEDs) and organic photovoltaics (OPV). For the improvement of performance and efficiency, correct modeling of the electronic processes in the devices is essential. Reliable characterization and validation of the electronic properties of the materials is simultaneously required for the successful optimization of devices. Furthermore, understanding the relations between material structures and their key characteristics opens the path for innovative material and device design. In this thesis, two material characterization methods are developed, respectively refined and applied: a novel technique for measuring the charge carrier mobility μ and a way to determine the ionization energy IE or the electron affinity EA of an organic semiconductor. For the mobility measurements, a new evaluation approach for space-charge limited current (SCLC) measurements in single carrier devices is developed. It is based on a layer thickness variation of the material under investigation. In the \"potential mapping\" (POEM) approach, the voltage as a function of the device thickness V(d) at a given current density is shown to coincide with the spatial distribution of the electric potential V(x) in the thickest device. On this basis, the mobility is directly obtained as function of the electric field F and the charge carrier density n. The evaluation is model-free, i.e. a model for μ(F, n) to fit the measurement data is not required, and the measurement is independent of a possible injection barrier or potential drop at non-optimal contacts. The obtained μ(F, n) function describes the effective average mobility of free and trapped charge carriers. This approach realistically describes charge transport in energetically disordered materials, where a clear differentiation between trapped and free charges is impossible or arbitrary. The measurement of IE and EA is performed by characterizing solar cells at varying temperature T. In suitably designed devices based on a bulk heterojunction (BHJ), the open-circuit voltage Voc is a linear function of T with negative slope in the whole measured range down to 180K. The extrapolation to temperature zero V0 = Voc(T → 0K) is confirmed to equal the effective gap Egeff, i.e. the difference between the EA of the acceptor and the IE of the donor. The successive variation of different components of the devices and testing their influence on V0 verifies the relation V0 = Egeff. On this basis, the IE or EA of a material can be determined in a BHJ with a material where the complementary value is known. The measurement is applied to a number of material combinations, confirming, refining, and complementing previously reported values from ultraviolet photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES). These measurements are applied to small molecule organic semiconductors, including mixed layers. In blends of zinc-phthalocyanine (ZnPc) and C60, the hole mobility is found to be thermally and field activated, as well as increasing with charge density. Varying the mixing ratio, the hole mobility is found to increase with increasing ZnPc content, while the effective gap stays unchanged. A number of further materials and material blends are characterized with respect to hole and electron mobility and the effective gap, including highly diluted donor blends, which have been little investigated before. In all materials, a pronounced field activation of the mobility is observed. The results enable an improved detailed description of the working principle of organic solar cells and support the future design of highly efficient and optimized devicesOrganische Halbleiter sind eine neue Schlüsseltechnologie für großflächige und flexible Dünnschichtelektronik. Sie werden als dünne Materialschichten (Sub-Nanometer bis Mikrometer) auf großflächige Substrate aufgebracht. Die technologisch am weitesten fortgeschrittenen Anwendungen sind organische Leuchtdioden (OLEDs) und organische Photovoltaik (OPV). Zur weiteren Steigerung von Leistungsfähigkeit und Effizienz ist die genaue Modellierung elektronischer Prozesse in den Bauteilen von grundlegender Bedeutung. Für die erfolgreiche Optimierung von Bauteilen ist eine zuverlässige Charakterisierung und Validierung der elektronischen Materialeigenschaften gleichermaßen erforderlich. Außerdem eröffnet das Verständnis der Zusammenhänge zwischen Materialstruktur und -eigenschaften einen Weg für innovative Material- und Bauteilentwicklung. Im Rahmen dieser Dissertation werden zwei Methoden für die Materialcharakterisierung entwickelt, verfeinert und angewandt: eine neuartige Methode zur Messung der Ladungsträgerbeweglichkeit μ und eine Möglichkeit zur Bestimmung der Ionisierungsenergie IE oder der Elektronenaffinität EA eines organischen Halbleiters. Für die Beweglichkeitsmessungen wird eine neue Auswertungsmethode für raumladungsbegrenzte Ströme (SCLC) in unipolaren Bauteilen entwickelt. Sie basiert auf einer Schichtdickenvariation des zu charakterisierenden Materials. In einem Ansatz zur räumlichen Abbildung des elektrischen Potentials (\"potential mapping\", POEM) wird gezeigt, dass das elektrische Potential als Funktion der Schichtdicke V(d) bei einer gegebenen Stromdichte dem räumlichen Verlauf des elektrischen Potentials V(x) im dicksten Bauteil entspricht. Daraus kann die Beweglichkeit als Funktion des elektrischen Felds F und der Ladungsträgerdichte n berechnet werden. Die Auswertung ist modellfrei, d.h. ein Modell zum Angleichen der Messdaten ist für die Berechnung von μ(F, n) nicht erforderlich. Die Messung ist außerdem unabhängig von einer möglichen Injektionsbarriere oder einer Potentialstufe an nicht-idealen Kontakten. Die gemessene Funktion μ(F, n) beschreibt die effektive durchschnittliche Beweglichkeit aller freien und in Fallenzuständen gefangenen Ladungsträger. Dieser Zugang beschreibt den Ladungstransport in energetisch ungeordneten Materialien realistisch, wo eine klare Unterscheidung zwischen freien und Fallenzuständen nicht möglich oder willkürlich ist. Die Messung von IE und EA wird mithilfe temperaturabhängiger Messungen an Solarzellen durchgeführt. In geeigneten Bauteilen mit einem Mischschicht-Heteroübergang (\"bulk heterojunction\" BHJ) ist die Leerlaufspannung Voc im gesamten Messbereich oberhalb 180K eine linear fallende Funktion der Temperatur T. Es kann bestätigt werden, dass die Extrapolation zum Temperaturnullpunkt V0 = Voc(T → 0K) mit der effektiven Energielücke Egeff , d.h. der Differenz zwischen EA des Akzeptor-Materials und IE des Donator-Materials, übereinstimmt. Die systematische schrittweise Variation einzelner Bestandteile der Solarzellen und die Überprüfung des Einflusses auf V0 bestätigen die Beziehung V0 = Egeff. Damit kann die IE oder EA eines Materials bestimmt werden, indem man es in einem BHJ mit einem Material kombiniert, dessen komplementärer Wert bekannt ist. Messungen per Ultraviolett-Photoelektronenspektroskopie (UPS) und inverser Photoelektronenspektroskopie (IPES) werden damit bestätigt, präzisiert und ergänzt. Die beiden entwickelten Messmethoden werden auf organische Halbleiter aus kleinen Molekülen einschließlich Mischschichten angewandt. In Mischschichten aus Zink-Phthalocyanin (ZnPc) und C60 wird eine Löcherbeweglichkeit gemessen, die sowohl thermisch als auch feld- und ladungsträgerdichteaktiviert ist. Wenn das Mischverhältnis variiert wird, steigt die Löcherbeweglichkeit mit zunehmendem ZnPc-Anteil, während die effektive Energielücke unverändert bleibt. Verschiedene weitere Materialien und Materialmischungen werden hinsichtlich Löcher- und Elektronenbeweglichkeit sowie ihrer Energielücke charakterisiert, einschließlich bisher wenig untersuchter hochverdünnter Donator-Systeme. In allen Materialien wird eine deutliche Feldaktivierung der Beweglichkeit beobachtet. Die Ergebnisse ermöglichen eine verbesserte Beschreibung der detaillierten Funktionsweise organischer Solarzellen und unterstützen die künftige Entwicklung hocheffizienter und optimierter Bauteile
37
Diac, Andreea Petronela. "Design, synthesis and supramolecular architectures of new heterocyclic compounds with potential applications in material chemistry and photovoltaic conversion". Thesis, Angers, 2015. http://www.theses.fr/2015ANGE0019/document.
Abstract (sommario):
La thèse intitulée «Design, Synthesis and SupramolecularArchitectures of New Heterocyclic Compounds with PotentialApplications in Material Chemistry and Photovoltaic Conversion” eststructurée en cinq chapitres traitant de nouveaux: a)cyclopenta[c]pyrannes hétérocyclique; b)des propriétés fluorescentes; d) potentiels dispositifs de l'électroniquemoléculaire; d) donneurs moléculaires pour les photovoltaïquesorganiques et e) carbon‘quantum’dots électroluminescents.Le premier chapitre présente une étude des dérivéspseudoazulenique ayant une unité cyclopenta[porte sur leur synthèse, l'analyse structurale et leur comportement dansdes réactions de substitution électrophile pour obtenir des composésayant des propriétés fluorescentes.Le deuxième chapitre présentediastéréoisomères et l'étude de propriétés de fluorescencedérivés d’indenopyrone.Le troisième chapitre décrit la synthèse des nouvellesarchitectures basées sur l’unité cyclopenta[être modifiés structurellement par l'influence d'un stimulus chimiqueou électrochimique afin d'élaborer des potentiels dispositifs del'électronique moléculaire.Dans le quatrième chapitre, la synthèsedes propriétés électroniques des nouvelles molécucellules solaires organiques (OSC) ontLe cinquième et dernier chapitre décrit la passivation desdéfauts de surface des nanoparticules de carbone avec desmolécules organiques ou des polymères pour obtenir desnanoparticules de carbone photoluminescentse surnommé ‘quantum dotsThe thesis entitled “Design, Synthesis and SupramolecularArchitectures of New Heterocyclic Compounds with PotentialApplications in Material Chemistry and Photovoltaic Conversion” isstructured into five chapters concerning new: a) heterocycliccyclopenta[c]pyrans; b) indenopyrone derivatives with fluorescentproperties; c) potential devices of molecular electronics; d)donors for organic photovoltaics and e) electroluminescent carbon‘quantum’ dots.The first chapter presents a study of pseudoazulenederivatives having a cyclopenta[c]pyran unit. The survey comprises thesynthesis, structural analysis and reactivity towards electrophilicsubstitution in order to obtain fluorescent compounds.The second chapter deals with the separation odiastereoisomers and the study of fluorescent propertiesindenopyrone derivatives.The third chapter describes the synthesis of newarchitectures based on cyclopenta[c]pyran unit that can be structurallymodified by the influence of a chemical or electrochemical stimulus inorder to work as potential devices in molecular electronics.In the fourth chapter, the synthesis andelectronic properties of new molecular donors for organic solar cellswas described.The fifth and last chapter outlines the passivation of surfacedefects on carbon nanoparticles using small organic molecules orpolymers in order to obtain photoluminescent carbon nanoparticlesdubbed as carbon‘quantum’dots
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Rabah, Jad. "Assemblages donneur-accepteur à base de BODIPY-[60]Fullerène pour l’électronique organique : Synthèse, caractérisation, et modification de surface Photoinduced Electron Transfer and Energy Transfer Processes in a Flexible BODIPY‑C60 Dyad Synthesis of a Dual Clickable Fullerene Platform and Construction of a Dissymmetric BODIPY-[60]Fullerene DistyrylBODIPY Triad A fullerene helical peptide: synthesis, characterization and formation of self-assembled monolayers on gold surfaces". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF036.
Abstract (sommario):
Ce manuscrit de thèse porte sur la synthèse de nouveaux assemblages covalents Donneur(s)-Accepteur(s) [BODIPY(s)-C60(s), BDP-C60] qui pourraient conduire à des applications potentielles en électronique organique et en photo-catalyse. Pour atteindre ces objectifs, nous avons dans un premier temps mis au point une nouvelle stratégie de synthèse permettant la double fonctionnalisation d’un dérivé du C60, par différents BDP(s), via des réactions de chimie clic. Cette nouvelle stratégie a permis la synthèse d’assemblages BPD(s)-C60(s) complexes conduisant à des processus photo-induits multiples liés à l’arrangement des différents partenaires (transfert d’électron et/ou transfert d’énergie). La seconde partie de cette thèse a porté sur la synthèse et la caractérisation de dérivés du BDP étendus fonctionnalisés par une ou deux unités ferrocène(s) (Fc) ou tetrathiafulvalène(s) (TTF). Ces assemblages présentent des propriétés d’absorption étendues dans le domaine du visible voire dans le proche IR dans certains cas. En outre, une bonne communication électronique entre les unités redox (Fc-BDP ou TTF-BDP) à l’état fondamental et excité a été mise en évidence. La modulation de l’émission de fluorescence du BDP dans certains de ces assemblages a également été mise en évidence par modification de l’état redox (du TTF ou du Fc) ouvrant la voie à des applications en électro-fluorochromisme.Ces assemblages ont été par la suite greffés sur la nouvelle plateforme C60 d’une manière simple et efficace. Les premières études réalisées sur les assemblages (Fc(s))-BDP-C60 ont révélé l’existence de processus de transfert d’électron en cascade, suite à la photo-excitation du BDP, avec une augmentation considérable des temps de vie des états de charges séparées. La dernière partie de ce manuscrit expose les résultats obtenus lors de l’immobilisation des systèmes BDP-C60 sur des surfaces d’or sous la forme de monocouches auto-assemblées. L’objectif est ici de développer des cellules photo-électrochimiques organiques (PEC) pour la génération de photo-courant. Pour réaliser cet objectif, ces assemblages BDP-C60 ont été modifiés par un hexa-peptide adoptant une conformation hélicoïdale, ce dernier permettant une meilleure structuration de la surface et un meilleur transport des électrons vers la surface métallique comparativement à une chaîne alkyle. Lors de cette partie, nous avons montré que l’association du peptide au C60 conduisait à une meilleure structuration de la surface par comparaison à une chaîne alkyle. Enfin, l’incorporation de monocouches auto-assemblées à base de (BDP)-C60-peptide dans des cellules photo-électrochimiques a montré une meilleure efficacité en termes de génération de photo-courant comparativement aux analogues fonctionnalisés par une chaîne alkyleThis manuscript describes the synthesis and characterization of novel BODIPY-[60]Fullerene –based Donor-Acceptor conjugates for applications in organic electronics and photocatalysis.In the first part of this dissertation, we report the elaboration of a novel dual clickable methanofullerene building block that can be functionalized, on both sides of the C60, by different BDP light-harvester/electron donor appendages. This strategy allowed the efficient and straightforward construction of complex BDP-C60 –based arrays exhibiting multiple photoinduced events (electron or /and energy transfer) brought by the closely-spaced arrangement between the redox counterparts. In the second part of this thesis, we report the synthesis and characterization of extended-BDP derivatives containing one or two units of Ferrocene (Fc) or tetrathiafulvalene (TTF) donors. The resulting conjugates displayed remarkable light-harvesting properties with wide absorption in the visible region that can be extended to the NIR in some cases. In addition, a good electronic communication between the redox centers (Fc-BDP or TTF-BDP) at the fundamental or/and excited states was demonstrated in these conjugates. The modulation of the BDP emission within these assemblies was also investigated by switching the redox properties of the TTF and Fc moieties. Moreover, these TTF-BDP and Fc-BDP systems were consecutively connected to the newly-described methanofullerene platform using our described synthetic strategy in the previous part, which resulted in the formation of TTF-BDP-C60 and Fc-BDP-C60 assemblies in an efficient manner. These derivatives exhibited interesting photophysical and photodynamic properties thanks to the occurrence of efficient cascade PET processes, resulting in the formation of relatively-long charge-separated state lifetimes. Finally, in the last part of this dissertation, we report the immobilization of the BDP-C60 and extended-BDP-C60 –based assemblies on gold surfaces through the formation of self-assembled monolayers (SAMs) for the design of photoelectrochemical cells (PEC). For this, we appended a helical peptide, playing a dual role as structuring agent and good electron mediator, between the metallic surface and the redox centers. The association of the (BDP)-C60 derivatives with the peptide spacer appeared as a successful strategy for the formation of more dense and vertically-oriented monolayers, when compared to their alkyl chains analogs. The incorporation of the SAM-based BDP-C60-peptide assemblies in a PEC device revealed interesting photocurrent generation properties, which makes these assemblies potential candidates for organic electronics applications
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Aguiar, António Luís Gonçalves de. "New boron-dipyrromethene (BODIPY) molecules as suitable electron-donors for organic photovoltaic cells". Doctoral thesis, 2019. http://hdl.handle.net/10316/88807.
Abstract (sommario):
Tese no âmbito do Doutoramento em Química, Ramo de Especialização em Química Macromolecular apresentada ao Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.As células fotovoltaicas orgânicas (OPVs) têm surgido como uma das alternativas mais apelativas às células fotovoltaicas baseadas em semicondutores inorgânicos (essencialmente silício), devido ao baixo custo de produção, leveza, flexibilidade dos dispositivos e versatilidade na integração em edifícios. As moléculas de boro-dipirrometeno (BODIPY) são fotossensibilizadores muito promissores para aplicação em OPVs. Contudo, a aplicação de BODIPYs em células fotovoltaicas orgânicas começou a ser investigada há apenas 10 anos e o número de publicações é ainda relativamente baixo. Esta tese de doutoramento abrange a síntese, caracterização e aplicação fotovoltaica de várias moléculas de BODIPY divididas em quatro séries. A primeira série é composta maioritariamente por BODIPYs meso-substituídos cuja estrutura permite funcionalizações adicionais. Os resultados dos estudos das principais propriedades estruturais, fotofísicas, eletroquímicas, bem como os resultados dos testes fotovoltaicos serviram como base comparativa para a avaliação das moléculas subsequentes. As restantes três séries foram construídas a partir da funcionalização de algumas estruturas da primeira série. A segunda e terceira série são constituídas maioritariamente por novas estruturas com grupos estireno ou grupos vinílicos obtidos a partir da condensação de aldeídos aromáticos com alguns BODIPYs selecionados da primeira série, via condensação de Knoevenagel. Estes novos compostos possuem uma maior conjugação de eletrões-π e, por isso, uma absorção e emissão deslocadas para maiores comprimentos de onda. As moléculas de BODIPY da quarta série foram obtidas através da substituição dos ligandos típicos (átomos de flúor) por vários grupos ariloxi ou alcoxi. Adicionalmente, foram também sintetizadas três moléculas conjugadas de BODIPY-porfirina, usando um método de síntese já conhecido e um método alternativo desenvolvido ao longo do projeto doutoral. O novo método de síntese usa porfirinas com grupos carboxílicos para sintetizar BODIPYs diretamente ligados à estrutura das porfirinas. Além das técnicas de caracterização estrutural padrão (por exemplo, espectroscopia de ressonância magnética nuclear, espectrometria de massa), os compostos sintetizados foram estudados através de técnicas como termogravimetria, calorimetria diferencial de varredura, espectroscopia de absorção, espectroscopia de emissão, voltametria cíclica e estudos computacionais. A conjugação de todas as técnicas de caracterização permitiu obter um conhecimento abrangente das propriedades dos BODIPYs, calcular as energias das viii orbitais HOMO e LUMO, e avaliar a adequabilidade dos compostos para aplicação em OPVs. Todas as moléculas sintetizadas foram consideradas doadoras de eletrões adequadas (em combinação com os aceitadores de eletrões PC61BM e PC71BM) à aplicação em células fotovoltaicas orgânicas. Consequentemente, a maioria dos BODIPYs sintetizados foram testados e as melhores OPVs foram otimizadas em vários aspetos relativos à construção dos dispositivos. Em geral, as OPVs baseadas nas moléculas propostas apresentaram altas tensões de circuito aberto (VOC), e alguns sistemas atingiram eficiência de conversão de energia (PCE) acima de 2 %. O melhor resultado foi alcançado por um BODIPY com duas unidades de vinilnaftaleno, com um PCE de 2.8 % e VOC de 1.00 V, o que é uma eficiência muito promissora tendo em conta as OPVs baseadas em BODIPYs já publicadas, e um valor de VOC alto considerando qualquer tipo de célula fotovoltaica orgânica.
Organic photovoltaic cells (OPVs) have been arising as one of the most appealing alternatives to the photovoltaic cells based on inorganic semiconductors (mainly silicon) due to their low-cost production, lightweight, mechanical flexibility and versatility for building integration. Boron-dipyrromethene (BODIPY) molecules are auspicious photosensitizer materials for OPV. However, the research on BODIPY-based OPVs just started 10 years ago and the number of published studies is relatively low. This thesis comprises the synthesis, characterization and photovoltaic application of several BODIPY molecules divided into four different series. The first series is composed by simple meso-substituted BODIPY dyes whose molecular framework allows further derivatizations. The result of the studies of the main structural, photophysical, electrochemical properties as well as the photovoltaic results were used as standard data for performance evaluation of the subsequent series. The other three series are made of BODIPYs obtained upon functionalization of selected molecules from the first series. The second and third series are mostly constituted by new BODIPY structures with styryl or vinyl groups, synthesised through condensation of aromatic aldehydes with some selected BODIPY structures from the first series, via Knoevenagel condensation. These new molecules presented an expansion of the π-system which led to absorption and emission at higher wavelengths. The BODIPY molecules from the fourth series were obtained by changing the typical BODIPY’s boron ligands (fluorine atoms) by several aryloxy or alkoxy groups. Additionally, three BODIPY-porphyrin dyads were synthesised using both a reported pathway and a pathway developed during the PhD project. The new pathway uses porphyrins with carboxylic acid groups to synthesise the BODIPY structure directly attached to porphyrin’s structure. In addition to the standard structural characterisation (e.g. nuclear magnetic resonance spectroscopy, mass spectrometry), the synthesised compounds were characterised using a variety of techniques, namely, thermogravimetry, scanning calorimetry, absorption spectroscopy, emission spectroscopy, cyclic voltammetry and computational studies. The conjugation of all characterisation techniques allowed us to obtain a full understanding of their main properties, calculate the HOMO and LUMO energies and evaluate the suitability for application in OPVs. vi All the synthesised compounds were considered suitable electron-donors (upon combination with PC61BM and PC71BM as electron-acceptors) for organic photovoltaic cells. Consequently, almost all BODIPYs were tested and the best performing BODIPY-based OPVs were optimised in several aspects related to the engineering of the devices. In general, OPVs based on the proposed dyes presented high open-circuit voltages (VOC), and some systems reached power conversion efficiency (PCE) above 2 %. The best result was achieved by a BODIPY with two vinylnaphthalene units, with a PCE of 2.8 % and VOC of 1.00 V, which is a very promising PCE result for BODIPY-based OPV and a top VOC value for this sort of systems.
40
Lu, Chih-Wei, e 呂誌偉. "Applications of Small Molecule Donors, Electron Transporting Materials, and Transparent Silver Nanowire Electrodes in Organic Solar Cells". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/71280929755194387323.
Abstract (sommario):
碩士國立清華大學
材料科學工程學系
101
In this thesis, I focus on the material characterization and the device optimization of small molecule organic solar cells (SMOSCs). In the first part, I briefly review the history and development of organic solar cells (OSCs), followed by working mechanisms, material preparation, device structures and measurement of OSCs. In the second part of thesis, before evaluting new donor compounds for SMOSCs, I review some previous reports of SMOSCs employing symmetrical or unsymmertrical small molecular donors. Among our symmetrical donor compounds, PyCN, a donor with the acceptor-acceptor-donor-acceptor-acceptor (A-A-D-A-A) molecular structure, shows the best performance in SMOSCs by utilizing the planar mixed heterojunction (PMHJ) strcuture. The optimized blend ratio is PyCN:C70 = 1.5:1 (by volume), giving a power conversion efficiency (PCE) of up to 4.3% with an open circuit voltage (Voc) of 0.95 V, short circuit current density (Jsc) of 12.50 mA/cm2, fill factor (F.F.) of 0.37. On the other hand, TDP with donor-acceptor-acceptor (D-A-A) molecular structures shows the most promising characteristics among our unsymmetrical donor systems. The TDP:C70 (1:2) PMHJ device exhibits the best performance of a PCE up to 5.6% with a Voc of 0.94 V, Jsc of 11.34 mA/cm2, F.F. of 0.52. In the third part, the electron transporting materials, TmPyPB, B3PyPB, BCP, BP4mPy, HATCN, DPPS, ET-7 and TC-1108 had been examined for the role of electron transporting layer (ETL) in OSCs. Among them, TmPyPB possesses the advantages of good thermal stability and high electron mobility, which make it a good ETL candidate for OSCs. In the long-term light soaking test, the TmPyPB-based cells also showed longer lifetime and less deterioration than the tranditional BCP-based cells. At the last part of this section, by using AC impedance analysis, I show that the TmPyPB-based cells exhibit the lowest AC resistance among all devices. In the fourth part, silver nanowire (AgNW) was used to replace indium tin oxide (ITO) as a transparent electrode for the OSCs. The P3HT:PCBM OSCs employing AgNW show a PCE up to 4%, which is highly comparable to the ITO-based reference cells. In the last part, I developed a physical vapor deposition technique for solar active layer deposition. In the priliminary test, DBP thin films and the bilayer heterojunction solar cells were fabricated using this deposition method.
41
Reitzenstein, Dörte. "Donor-Acceptor Conjugated Polymers for Application in Organic Electronic Devices". Doctoral thesis, 2010. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-53939.
Abstract (sommario):
In the first part of the work three polycarbazoles poly[N-((4-dimesitylboryl)-3,5-dimethylphenyl)-carbazole]-2,7-diyl P1, poly[N-((4-dimesitylboryl)-3,5-dimethylphenyl)-carbazole]-3,6-diyl P2 and poly[N-(4-(diphenylmethylene)-phenyl)- carbazole]-2,7-diyl P3 were synthesized by Yamamoto coupling reaction and their spectroscopic and electrochemical properties were investigated. Absorption and fluorescence characteristics of P1 and P3 were found to be similar to other 2,7-linked polycarbazoles, whereas P2 shows a CT absorption band arising from a shift of electron density from the nitrogen of the carbazole donor to the triarylborane acceptor. This causes a negative solvatochromic absorption and a positive solvatochromic fluorescence behaviour and is responsible for the significantly enlarged fluorescence quantum efficiency in solution and solid state compared to other 3,6-linked polycarbazoles. Thus the spectroscopic properties are governed by the connection pattern: the 2,7-linked polycarbazoles are not affected by the acceptor substituent due to the rigid poly-para-phenylene-like backbone structure, whereas the 3,6-linked polycarbazole P2 is dominated by the properties of the monomer unit due to its more flexible (less conjugated) structure. The oxidative processes of P1-P3 have been investigated in detail by cyclic voltammetry, which are similar to known 2,7- and 3,6-polycarbazoles. The reversible reduction found for P1 and P2, respectively, is attributed to the reduction of the triarylborane moiety. No reduction process referring to the carbazole moiety was observed. Due to its better solubility compared to P1 and P3 only P2 was used as active layer in an OLED device (ITO/P2/Al). The electroluminescence spectrum revealed CIE coordinates of (0.17, 0.21). In the second part of the work the low band gap polyradical poly{[((2,3,4,5,6-pentachlorophenyl)-bis(2,3,5,6-tetrachlorophenyl)methyl radical)-4,4’-diyl]-alt-4,4’-bis(vinylphenyl)-4-(2-ethylhexyloxy)phenylamin} P4 was synthesized by Horner-Emmons reaction. It shows an IV-CT band in the NIR, which arises from an ET from the triarylamine donor to the PCTM radical acceptor. This transition is confined to one monomer unit as deduced from comparison with the monomer spectra. HOMO and LUMO of P4 determined by cyclic voltammetry are at -5.5 and -4.5 eV, respectively. The smaller electrochemical band gap (1.0 eV) compared to the optical band gap (1.2 eV) is probably caused by ion pairing effects in the electrochemical experiments and indicates a low exciton binding energy. Femtosecond-pump-probe transient absorption spectroscopy revealed the spectral features of the oxidized triarylamine donor and the reduced PCTM acceptor similar to the spectra obtained separately for positive and negative potentials by spectroelectrochemistry. Thus the ET event causing the IV-CT absorption band could unambiguously be identified. The decay of the IV-CT state was found to be biexponential. The fast solvent dependent decay component is ascribed to the direct decay from the IV-CT state to the ground state, whereas the slow solvent independent decay component is tentatively attributed to an equilibrium formation of the IV-CT state and a completely charge separated state formed by charge migration along the polymer backbone. Well balanced ambipolar charge transport with hole and electron mobilities of ca. 3 × 10-5 cm2 V-1 s-1 was found in OFET devices (BG/TC structure) comprising an additional insulating organic PPcB layer. Polymer/polymer BHJ solar cell devices with the structure glass/ITO/PEDOT:PSS/(P3HT/P4)/Ca/Al yielded a power conversion efficiency of 3.1 × 10-3 %, VOC = 0.38 V, JSC = 2.8 × 10-2 mA cm-2 and FF = 0.29 for the 1:4 (P3HT/P4) blend ratio. The improper solid state morphology of P4 that causes the unsatisfying performance of OFET and solar cell devices renders P4 less suitable for these applications, whereas the hypothesis of charge migration in the excited state is worth to be investigated in more detailIm ersten Teil dieser Arbeit wurden die drei Polycarbazole Poly[N-((4-dimesitylboryl)-3,5-dimethylphenyl)-carbazol]-2,7-diyl P1, Poly[N-((4-dimesitylboryl)-3,5-dimethylphenyl)-carbazol]-3,6-diyl P2 und Poly[N-(4-(diphenylmethylen)-phenyl)-carbazol]-2,7-diyl P3 mittels Yamamoto Kupplung synthetisiert und ihre spektroskopischen und elektrochemischen Eigenschaften untersucht. Absorptions- und Fluoreszenzeigenschaften von P1 und P3 sind denen anderer 2,7-verknüpfter Polycarbazole ähnlich, wohingegen P2 eine CT Absorptionsbande zeigt, die durch die Verschiebung von Elektronendichte vom Stickstoff des Carbazoldonors zum Triarylboranakzeptor verursacht wird. Daraus ergeben sich negativ solvatochromes Absorptions- und positiv solvatochromes Fluoreszenzverhalten und eine deutlich erhöhte Fluoreszenzquantenausbeute in Lösung und im Festkörper verglichen mit anderen 3,6-verknüpften Polycarbazolen. Das bedeutet, dass die spektroskopischen Eigenschaften durch die Art der C-C-Verknüpfung gesteuert werden können: das 2,7-verknüpfte Polycarbazol P1 wird durch den Akzeptorsubstituenten aufgrund des starren Polymergerüsts, dem eine poly-para-phenylenartige und damit stärker delokalisierte Struktur zugrunde liegt, nicht beeinflusst. Im Gegensatz dazu treten beim 3,6-verknüpften Polycarbazol P2 die Eigenschaften der Monomereinheit aufgrund der flexibleren 1,4-diaminobiphenyl Struktur in den Vordergrund. Die Oxidationsprozesse von P1-P3 wurden im Detail mittels Cyclovoltammetrie untersucht. Die Ergebnisse stimmen mit Literaturwerten überein. Außerdem wurde bei den Messungen von P1 und P2 ein reversibler Reduktionsprozess, der am Boranzentrum stattfindet, beobachtet. Eine Reduktion der Carbazoleinheit konnte hingegen nicht gefunden werden. Mit der Herstellung von OLEDs der Struktur ITO/P2/Al konnte blaue Elektrolumineszenz mit den CIE Farbkoordinaten (0.17, 0.21) nachgewiesen werden. Im zweiten Teil der Arbeit wurde das low band gap Polyradikal Poly{[((2,3,4,5,6-pentachlorphenyl)-bis(2,3,5,6-tetrachlorphenyl)methyl radical)-4,4‘-diyl]-alt-4,4‘-bis(vinylphenyl)-4-(2-ethylhexyloxy)phenylamin} P4 mittels Horner-Emmons Reaktion synthetisiert. Im NIR beobachtet man eine IV-CT Absorptionsbande, die durch einen Elektronentransfer vom Triarylamindonor zum PCTM-Radikalakzeptor hervorgerufen wird. Dieser elektronische Übergang ist auf eine Monomereinheit begrenzt wie der Vergleich mit den Monomerabsorptionsspektren zeigt. HOMO und LUMO Energien von P4, die anhand der Cyclovoltammogramme bestimmt wurden, liegen bei -5.5 und -4.5 eV. Die im Vergleich zur optischen Energielücke (1.2 eV) kleinere elektrochemische Energielücke (1.9 eV) ist wahrscheinlich auf Ionenpaareffekte bei den elektrochemischen Messungen zurückzuführen, deutet aber auch auf eine geringe Excitonenbindungsenergie hin. Transiente Absorptionsspektren zeigen die spektralen Charakteristika von oxidiertem Triarylamindonor und reduziertem PCTM-Akzeptor vergleichbar mit den Spektren der spektroelektrochemischen Messungen, bei denen eine Lösung von P4 jeweils nacheinander reduziert und oxidiert wurde. Dadurch konnte der Elektronentransferprozess, der zur Ausbildung der IV-CT Bande führt, zweifelsfrei nachgewiesen werden. Der IV-CT Zustand zerfällt biexponentiell. Der schnelle, lösungsmittelabhängige Zerfall beschreibt den direkten Übergang vom IV-CT Zustand in den elektronischen Grundzustand. Dagegen wird der langsame, lösungsmittelunabhängige Zerfall einer Gleichgewichtseinstellung zwischen IV-CT Zustand und vollständig ladungsgetrenntem Zustand, der durch Ladungswanderung entlang der Polymerkette erreicht wird, zugeschrieben. In OFETs mit P4 als Halbleiter und einer zusätzlich isolierenden, organischen PPcB Schicht wurde ein ausgeglichener, ambipolarer Ladungstransport mit Loch- und Elektronenbeweglichkeiten von ca. 3 × 10-5 cm2 V-1 s-1 gefunden. Polymer/Polymer BHJ Solarzellenmodule mit der Struktur Glas/ITO/PEDOT:PSS/(P3HT/P4 1:4)/Ca/Al hatten einen Wirkungsgrad von 0.0031 % bei einer Leerlaufspannung VOC = 0.38 V, einem Kurzschlussstrom JSC = 0.028 mA cm-2 und einem Füllfaktor FF = 0.29. Die ungeeignete Morphologie der P4- und P3HT/P4-Schichten als Ursache für die unbefriedigende Performance von OFETs und Solarzellen lässt solche Anwendungen für P4 wenig sinnvoll erscheinen. Dagegen verdient die Hypothese der Ladungswanderung im angeregten Zustand eine vertiefte Untersuchung
42
Kuo, Hsing-Chen, e 郭幸甄. "Synthesis and Properties of Dipolar Organic Molecules containing electron Donor and Acceptor Substituents". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/05719217209291791077.
Abstract (sommario):
碩士國立中央大學
化學研究所
94
Starting from Heptcyclo [6.6.0.02.6.03.13.04.11.05.9.010.14] tetradecane (HCTD), we were able to synthesize a series of donor-bridge-acceptor substituted derivatives by condensation reaction. The component for the condensation was 1,3-indanedione for the acceptor part. We also synthesized the reference compounds by using the Wolff-Kishner reduction. Fluorescence spectra provided evidence for efficient photoinduce electron transfer.
43
Chow, Boting, e 周柏廷. "Synthesis and Properties of Cage-shaped Organic Molecules Containing Electron Donor and Acceptor Groups". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/63090349228823392976.
Abstract (sommario):
碩士中國文化大學
應用化學研究所
96
Synthesis and Properties of Cage-shaped Organic Molecules Containing Electron Donor and Acceptor Groups Chingyang Liu , Tahsin J. Chow* Starting from Heptcyclo [6.6.0.02.6.03.13.04.11.05.9.010.14] tetradecane (HCTD), we were able to synthesize a series of donor-bridge-acceptor substituted derivatives by Sonogashira coupling rection and condensation reaction. The component for the condensation was 1,3-indanedione and diethyl malonate for the acceptor part. Fluorescence spectra provided evidence for efficient photoinduce electron transfer in only the compound 14、17 and 18, but not in the compound 20 and 21.
44
Vasylieva, Marharyta. "Electrochemical and spectroelectrochemical studies of electronic interactions in donor-acceptor-donor (DAD) and donor-acceptor (DA) systems". Rozprawa doktorska, 2021. https://repolis.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=71932.
45
Vasylieva, Marharyta. "Electrochemical and spectroelectrochemical studies of electronic interactions in donor-acceptor-donor (DAD) and donor-acceptor (DA) systems". Rozprawa doktorska, 2021. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=71932.
46
Ye, Jyun-Ming, e 葉竣銘. "Synthesis of Indolo[3,2-b]indole Arene as A New Electron Donor for Organic Photovoltaic Applications". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/35604559875368521058.
Abstract (sommario):
碩士國立交通大學
應用化學系碩博士班
100
Indolo[3,2-b]indole, containing two fused indole units, is an promising and attractive electron-rich monomer for constructing donor-acceptor materials due to its planar, symmetric, and extended conjugated structure. It is of interest to incorporate indolo[3,2-b]indole unit into a donor-acceptor ??conjugated system via its 2,7 or 3,8 positions to investigate the electronic and steric effects. In this research, we have successfully developed a new synthetic scheme to prepare 2,7-dibromo-indolo[3,2-b]indole. Unexpectedly, in an attempt to make 3,8-diromo-indolo[3,2-b]indole by following a procedure in the literature, we found that the bromination of indolo[3,2-b]indole turns out to occur at 2,7 positions rather than 3,8 positions. This finding confirms that 2,7 positions of indolo[3,2-b]indole actually possess stronger nucleophilicity to undergo electrophilic aromatic substitution reaction. 2,7-dibromoindolo[3,2-b]indole was then converted to the corresponding boronic ester monomer M1. The Suzuki coupling of M1 with monobrominated and dibrominated dithienodiketopyrrolopyrrole (DPP) led to an acceptor-donor-acceptor small molecule 2,7-bis(dithienoldiketopyrrolopyrrole)indolo[3,2-b]indole (2,7-BDPPII) and an alternating donor-acceptor copolymer PDPPII, respectively. On the other hand, M1 was also copolymerized with the benzothiadiazole (BT) unit to prepare two random copolymers PIIDTBT11 and PIIDTBT13. All the materials exhibited good thermal stabilities with the decomposition temperature ranging from 386 to 486 oC. The thin-film X-ray diffraction pattern of 2,7-BDPPII exhibited a crystalline structure. In addition, the absorption spectrum of 2,7-BDPPII in the solid state also showed red-shifted and band broadening behaviors compared to the solution state. These results indicated that highly planar structure of indolo[3,2-b]indole unit can enhance the intermolecular interaction. PDPPII showed the lower optical band gap of 1.45 eV than the small molecule 2,7-BDPPII (1.66 eV) as a result of longer conjugation length. The bulk heterojunction devices using the configuration of ITO/PEDOT:PSS/D-A material:PC71BM/Ca/Al were fabricated to evaluate these new materials. After thermal annealing at 150 oC for 7 min, the device incorporating 2,7-BDPPII as the active layer exhibited a Voc of 0.72 V, a Jsc of 6.88 mA/cm2 and a FF of 49.6%, leading to a PCE of 2.45%. This value is rather promising for small molecule-based solution processing BHJ solar cells. It is anticipated that the efficiency can be improved by further optimization of device fabrication. However, the PDPPII–based device exhibited very low performance due to the poor morphology associated with severe phase separation. The devices using PIIDTBT11 and PIIDTBT13 delivered the efficiencies of 0.65% and 0.59%, respectively.
47
Reitzenstein, Dörte [Verfasser]. "Donor-acceptor conjugated polymers for application in organic electronic devices / vorgelegt von Dörte Reitzenstein". 2010. http://d-nb.info/1009899856/34.
48
Bheemaraju, Amarnath. "Effect of side chains on organic donor (D) and acceptor (A) complexes and photophysical properties of D-A dyads". 2011. https://scholarworks.umass.edu/dissertations/AAI3482586.
Abstract (sommario):
This dissertation aims to understand the effect of incompatible side chains on the complexes of π-conjugated electron-rich donors and electron-deficient acceptors in solution. The role of incompatible side chains were studied in simple mixtures of organic donor and acceptor molecules that form donor-acceptor complexes. The incompatible branched and linear alkane side chains on the acceptor and donor respectively prevented complex formation between naphthalene diimide acceptor and naphthalene ether donor. However, the incompatible hydrocarbon-fluorocarbon and polar-non polar side chain pairs did not affect complex formation between the donor and acceptor. In quaterthiophene-naphthalene diimide dyads, the incompatibility of the side chain on the acceptor with respect to the side chain on the donor do not have any influence on the donor-acceptor complex formation. Irrespective of the attached side chains, all the dyads show charge transfer absorption bands and have similar electron transfer rates. The effect of point of attachment of the acceptor to the donor in the quaterthiophene-flavin dyad is also studied.
49
Mukhopadhyay, Sukrit. "Theoretical Studies Of Electronic Properties And Electronic Processes In Conjugated Molecules". Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1265.
Abstract (sommario):
This thesis deals with theoretical studies of electronic properties of organic conjugated molecules. The first chapter introduces different classes of organic conjugated molecules which possess high hole mobility, large quadratic non-linear response and low band gap. In this chapter, we further describe different photo-physical processes and the basic principles of various opto-electronic devices. The second chapter provides an introduction to various many-body techniques, which are employed in studying ground and excited state properties of organic conjugated systems. First, we describe the Hartree-Fock theory and the Density Functional (DFT) method. These are followed by full Configuration-Interaction (CI) methods and various semi-empirical methods (CNDO, INDO and NDDO). The INDO method is used in subsequent chapters to obtain the ground and excited state properties of organic conjugated molecules. In addition, we describe the restricted CI (SCI and SDCI) and the Density Matrix Renormalization Group (DMRG) methods. The third chapter of this thesis deals with a time evolution study to ascertain the role of the triplet state in the green emission of the ethyl-hexyl substituted poly-fluorene (PF2/6) films. To understand this phenomenon, we have modeled various non-radiative processes like (i) Inter-System Crossing (ISC), (ii) electron-hole Recombination (e-hR) and (iii) Triplet Quenching (TQ). These studies conclusively prove the contribution of triplet states to the 500 nm EL peak. In chapter four, we describe the origin of the unusual EL in tri-p-tolylamine (TTA) based hole conductors. In order to model this phenomenon, we have performed SCI calculations on TTA, its radical ions and allied hole conductors (TAPC and TPD). These calculations indicate that the unusual EL is due to low-lying charge-transfer (CT) state, which is stabilized by charge-dipole and charge-induced-dipole interactions. In chapter five, we turn our attention to the calculation of ground and excited state properties of a class of donor-acceptor (DA) system using ab-initio DFT and INDO methods. In these systems, DFT calculations along with INDO-SCI calculation, show strong intramolecular charge transfer interaction between the D and the A units. We have further calculated various properties like permanent dipole moments, oscillator strengths, Stoke’s shifts in various solvents etc. In chapter six, we focus on studying linear and non-linear optical properties of first generation nitrogen based dendrimers, using DMRG method. A novel scheme which includes the weights of the dipole allowed states in the computation of the density matrix is developed to obtain accurate dipole allowed excited states as well as the linear and nonlinear optical responses. Chapter seven deals with non-linear optical properties of weak donor-acceptor (DA) complexes formed between methyl substituted phenylenes (donor) and Chloranil or DDQ (acceptors). We have calculated the ground and the low-lying excited states of these DA complexes using INDO-SDCI method. The first hyperpolarizability (β) response coefficients are calculated using the Correction Vector (CV) technique, which are further used to obtain macroscopic depolarization ratios. By comparing the theoretical results with experimental findings, it can be shown that the slipped parallel configuration with a slight twist is the most preferred geometry of these weak DA complexes in solution.
50
Bill, Nathaniel Lloyd. "Extension of tetrathiafulvalene conjugation through pyrrollic-based dyes : ExTTF porphyrin and ExTTF BODIPY". Thesis, 2013. http://hdl.handle.net/2152/23527.
Abstract (sommario):
The research and development of organic electron donors is essential in the discovery of photodynamic therapy photosensitizers and catalysts, as well as in the fabrication of organic-based electronic devices. Recently, [pi]-extended tetrathiafulvalenes (exTTFs) have emerged as important organic donors due to their superb electronic properties. However, in general, exTTFs lack significant absorption in the visible and near-infrared portions of the electromagnetic spectrum, thereby limiting their utility. This doctoral dissertation depicts the author's efforts to address this inherent drawback of exTTFs by extending the electronic conjugation of tetrathiafulvalene moieties through pyrrole-based chromophores. The reported findings describe the design, synthesis, properties and potential applications of exTTFs with greatly enhanced absorption profiles. The first Chapter provides a brief historical overview on the history and development of [pi]-extended tetrathiafulvalenes. The various conjugated linkers utilized in exTTF systems are reviewed. In the latter part of the Chapter, emphasis is given to the applications in which exTTFs find use. Chapter 2, as the major focus of the dissertation, details the synthesis and characteristics of a quinoidal porphyrin-bridged exTTF, termed MTTFP. Several metalated complexes, including the Zn, Co, Cu, and Ni derivatives of MTTFP are reported. Additionally, the electrochemical, photophysical, and structural properties of MTTFPs are discussed. We also detail our efforts to synthesize and characterize both the one- and two-electron oxidized forms of MTTFPs. Finally, we discuss our efforts to reversibly switch thermodynamic electron transfer from ZnTTFP to Li@C₆₀ through coordination of axial ligands. Chapter 3 describes the formation of a 2:1 supramolecular ionic porphyrin complex between the two-electron oxidized form of ZnTTFP and a tetranionic sulfonated porphyrin. The association constants and the X-ray crystal structure of the complex are reported. A brief discussion outlining the photophysical characteristics (performed in Prof. Shunichi Fukuzumi and Prof. Dongho Kim's group) of the porphyrin donor-acceptor complexes are included. Chapter 4 details the synthesis, photophysical properties, and spectroelectrochemistry of a difluoroboradiazaindacene (BODIPY) bridged exTTF. This compound is referred to as ex-BODIPY. A singlet oxygen generation study provides initial evidence that ex-BODIPY could potentially serve as a photosensitizer. All of the experimental procedures, characterization data, and X-ray crystallographic data tables are reported in Chapter 5.text