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SARRITZU, VALERIO. "Photophysics of organic/inorganic lead halide perovskites". Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/255939.
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In keeping with their nature of hybrid materials, halide perovskites have been found to possess a particularly attractive blend of optoelectronic properties. A wealth of literature has been produced, that on some occasions raised questions just as readily as it answered them. In particular, my thesis addresses the following four key issues. First, the nature of the band gap. Long assumed to be the direct, according to recent reports the band gap supposedly has a dual nature. This fundamental matter is addressed through a study of the radiative recombination rates as a function of temperature. Data show that in perovskites radiative recombination becomes faster with decreasing temperature, as indeed in all direct-band gap materials. Second, exciton formation. Countless reports agree that free carriers are the majority photoexcited species under typical operating conditions of a solar cell, while evidence of exciton formation and dissociation processes is still elusive. A differential photoluminescence technique is employed to access extremely low injection levels at which emission from primary (geminate) excitons outshines that of free carriers. Third, efficiency loss. Understanding what processes limit the power conversion efficiency of perovskite solar cells is essential for the technology to mature. Shockley-Read-Hall and interface recombination are unambiguously identified as the main recombination mechanisms in perovskites and perovskite heterostructures, respectively. Fourth, solution processed nanostructures. A solution method developed by co-worker Dr Daniela Marongiu is shown to be able to form stable self-assembled MAPbI3-xBrx nanocrystals in a MAPbBr3 matrix. A thorough investigation on the photophysics of this material reveals that photoexcited charge carriers are funneled from the matrix to the nanocrystals, lifting quantum yield by one order of magnitude.
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Niu, Wendy Wanru. "Excitons in 2D organic-inorganic lead iodide perovskites". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708847.
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SESTU, NICOLA. "Optical properties of organic-inorganic lead halide perovskites". Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/259899.
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One of the most important challenges for our society is to make more efficient devices in order to mitigate the rapidly increasing energy demand. In recent years a class of materials have attracted a great deal of attention in this perspective. Thanks to unique properties, including high absorption coefficient, broad absorption spectrum, high charge-carrier mobilities, long diffusion lengths, tunable band gap and low costs of fabrication, organic-inorganic lead halide perovskites have become very promising candidates for a new generation of potentially printable and efficient optoelectronic devices.
The thesis aims to investigate some of the issues of optical properties of organic-inorganic lead halide perovskites.
First, the nature of the band gap. Nevertheless for a long time it was considered direct, recent reports have proposed that the presence of heavy atoms in the crystal leads to Rashba-type effects. This crucial issue is addressed thanks to a study of the radiative recombination rates and photoluminescence decay dynamics as a function of temperature, the direct nature of band gap is demonstrated.
Second, the exciton binding energy. Its knowledge is crucial for optoelectronic devices advances. Different measurement methods led to quite various each other values, even on the most widely studied materials, such as methylammonium lead iodide and methylammonium lead bromide. Thanks to a f-sum rule for integrated UV-vis absorption spectra, that allows to circumvent the pitfalls of least-squares fitting procedures, more accurate values of exciton binding energy is calculated and its dependence on temperature for these materials is shown.
Third, the excitons formation and dissociation. Even though its understanding is of fundamental importance, many aspects of the processes of formation of an exciton population in perovskites are still elusive and some questions are still to be answered. The differential photoluminescence technique presented is able to provide a comprehensive picture of the kinetics of excitons in hybrid perovskites and to unveil the spectroscopic sign of excitons.
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Dooley, Joan Mary 1961. "LEAD MOBILIZING ACTIVITY OF DMPS, DMSA, AND DMPA FOLLOWING ORGANIC AND INORGANIC LEAD EXPOSURE". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275507.
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Bhat, Jerome C. "Electroluminescent hybrid organic/inorganic quantum dot devices". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298766.
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Khozaee, Zahra. "Studies on organic/inorganic nanocomposites of lead sulphide quantum dots in solution- processed phthalocyanine films". Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8500.
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A unique organic/inorganic nanocomposite of lead sulphide (PbS) quantum dots (QDs) embedded in substituted metal-free phthalocyanine (C6H2Pc) has been prepared by a simple and low-cost method. The preparation procedure consists of exposure of a thin spun film of non-peripherally octa-hexyl lead phthalocyanine to hydrogen sulphide atmosphere. The formation of the PbS QDs has been verified using X-ray diffraction and transmission electron microscopy techniques. From the transmission electron microscopic measurements, the average size of the PbS QDs is found to be 4.5 nm, which is smaller than the exciton Bohr radius. Independent Xray diffraction and optical absorption studies provide supportive evidence for the size of QDs. Quantum confinement gives rise to a clear blue shift in the absorption spectrum with respect to the bulk PbS. The QDs band gap has been estimated to be 1.95 eV from Tauc's law and the frontier energy levels of the PbS QDs has been derived. About two orders of magnitude increase in ohmic conductivity, from 6.0×10−12 for C6H2Pc to 3.1×10−10 for the nanocomposite, is observed by steady-state electrical measurements in sandwich structure between indium tin oxide and aluminium. Temperature-dependence of the electrical conduction is studied aimed to calculate the activation energy and determine the type of conductivity. The incorporation of the PbS QDs decreases the activation energy by about 0.5 eV at temperatures higher than 240 K. It is found that the Poole-Frenkel mechanism is in good consistency with the superlinear electrical behaviour of the nanocomposite. The frequency response of alternating current (AC) conduction is found to obey the universal power-law. The cryogenic study of AC conduction reveals that the correlated barrier hopping (CBH) model closely fits to the experimental data at temperatures below 240 K. The parameters obtained by fitting the CBH model point out that the hopping process cannot take place directly between neighbouring PbS QDs but involves the localised states within the matrix.
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Mannsfeld, Stefan. "Ordering in weakly bound molecular layers: organic-inorganic and organic-organic heteroepitaxy". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1098888571984-95956.
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It is an aim of this work to provide insight into the energetic influence on the ordering of molecular thin films on crystalline substrates. Here, the term substrate either refers to inorganic crystal surfaces or highly ordered layers of another organic molecular species. In order to calculate the total interface potential of extended molecular domains, a new calculation technique (GRID technique) is developed in the first part of this work. Compared to the standard approach, this method accelerates the potential calculation drastically (times 10000). The other parts of the thesis are dedicated to the comparison of experimental results (obtained by scanning tunneling microscopy and electron diffraction) to the optimal layer structure as predicted by optimization calculations. Potential calculations which are performed for the system perylenetetracarboxylicdianhydride (PTCDA) on graphite demonstrate that point-on-line coincident structures correspond to energetically favorable alignments of the molecular lattice with respect to the substrate lattice. The capability of the GRID technique to predict the optimal layer structure is demonstrated for the system peri-hexabenzocoronene (HBC) on graphite. The organic-organic heteroepitaxy system PTCDA on HBC on graphite is investigated in order to clarify to which extent the ordering mechanism there differs from that of the organic-inorganic heteroepitaxy system PTCDA on graphite. As a result of this investigation, a new type of epitaxy, i.e., substrate induced ordering is found. This new epitaxy type is governed by the inner structure of the substrate lattice unit cell. Here, the substrate surface is a layer of organic molecules itself, hence the substrate surface unit cell does indeed exhibit a complex inner structure. A generalized classification scheme for epitaxial growth incorporating this new type of epitaxy is proposed. In the last chapter, the structure of the first layers of titanylphthalocyanine (TiOPc) on Au(111) is investigated and compared to potential optimization calculations. The correspondence of experimental and theoretical results provides evidence that the GRID technique can, in principle, also be applied to molecular layers on metal surfacesDas Ziel der vorliegenden Arbeit ist es, Einblicke in die energetischen Einflüsse, die zur Ausbildung der Schichtstruktur organischer Moleküle auf kristallinen Substraten führen, zu geben. Diese Substrate sind entweder Oberflächen anorganische Kristalle oder selbst hochgeordnete Molekülschichten. Um das totale Grenzflächenpotential ausgedehnter Moleküldomänen berechnen zu können, wird im ersten Teil der Arbeit eine neue Berechnungsmethode (GRID Technik) vorgestellt. Im Vergleich mit herkömmlichen Berechnungsmethoden auf der Basis molekülmechanischer Kraftfelder ist diese neue Methode daher um ein Vielfaches schneller (Faktor 100000). Die folgenden Teile der Arbeit sind dem Vergleich experimenteller Ergebnisse (Rastertunnelmikroskopie und Elektronenbeugung) mit, durch Potentialoptimierungsrechnungen als energetisch günstig vorhergesagten, Schichtstrukturen gewidmet. So kann für das System Perylentetracarbonsäuredianhydrid (PTCDA) auf Graphit mittels Potentialberechnungen nachgewiesen werden, daß die experimentell gefundenen ?Point-on-line koinzidenten? Strukturen energetisch günstige Anordnungen des Molekülgitters bezüglich des Substratgitters darstellen. Die Eignung der neuen Berechnungsmethode zur Vorhersage der günstigsten Adsorbatgitterstruktur für ein gegebenes System aus Molekül und Substrat, wird anhand des Systems peri-Hexabenzocoronen (HBC) auf Graphit demonstriert. Das organisch-organische Heteroepitaxiesystem PTCDA auf HBC auf Graphit wird untersucht, um zu klären, inwieweit sich die dafür gültigen Ordnungsmechanismen von denen unterscheiden, die für das Wachstum des organisch-anorganischen Heteroepitaxiesystems PTCDA auf Graphit verantwortlich sind. Dabei gelingt es, eine bisher nicht klassifizierte Art von Epitaxie, d.h. substratinduzierter Ordnung, nachzuweisen. Dieser neue Epitaxietyp ist bedingt durch die innere Struktur einer Substrateinheitszelle - das Substrat ist ja hier selbst eine Schicht geordneter Moleküle, die natürlich eine innere Struktur aufweisen. Im folgenden wird ein verallgemeinertes Klassifizierungssystem für Epitaxietypen abgeleitet, welches den neuen Epitaxietyp beinhaltet. Im letzten Kapitel wird die Struktur von der ersten Lagen von Titanylphthalocyanin (TiOPc) auf Au(111) experimentell untersucht und mit entsprechenden Potentialoptimierungsrechnungen verglichen. Die Übereinstimmung von experimentellen und theoretischen Ergebnissen zeigt, daß die GRID Technik, zumindest prinzipiell, auch für Molekülschichten auf Metallsubstraten anwendbar ist
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Öz, Senol [Verfasser]. "Process-, Solvent- and Chemical Engineering for Solution Processed Organic-Inorganic Lead Halide Perovskite Solar Cells / Senol Öz". München : Verlag Dr. Hut, 2018. http://d-nb.info/1170473601/34.
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Lystrom, Levi Aaron. "Influence of Organic and Inorganic Passivation on the Photophysics of Cadmium Chalcogenide and Lead Chalcogenide Quantum Dots". Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31926.
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Quantum dots (QDs) are promising materials for photovoltaic (PV) and light-emitting diode (LED) applications due to their unique properties: photostability, size-tunable absorptivity, and narrow line-width emission. These properties are tailored by surface passivations by ligands. However, ligands used in the synthesis of colloidal QDs need to be exchanged with ligands designed for specific applications. The mechanism behind ligand exchange is not well understood. Density functional theory (DFT) is utilized to gain fundamental understanding of ligand exchange (LE) and the resulting effect on the photophysics of QDs. Experimental studies show that phenyldithiocarbamates (PTCs) derivatives can improve the photocurrent of QD-based PVs. Our calculations show that the PTC undergoes decomposition on the CdSe QD surface. Decomposed products of PTCs strongly interact with the surface of QDs, which could cause unforeseen challenges during the implementation of these functionalized QDs in PVs. Secondly, we studied the mechanism of photoluminescence (PL) enhancement by hydride treatment. In experiments, the PL increases by 55 times, but the mechanism is unclear. We found that hydride can interact with surface Se2- producing H2Se gas and passivate surface Cd2+. These interactions result in optically active QDs. Thiol derivatives can also improve PL when LE results in low surface coverage of thiols. The PL is quenched if LE is performed at high concentrations and acidic environments. DFT simulations reveal three scenarios for the thiol interacts with QDs: coordination of thiol, networking between surface and/or other ligands, or thiolate formation. It is the last scenario that was found to be responsible for PL quenching. Lastly, PbS(e)/CdS(e) core/shell QDs are investigated to obtain relaxation rates of electron and hole cooling via interactions with phonons. The band structure of the core/shell QDs facilitates carrier multiplication (CM), a process that generates multiple charge carrier pairs per one absorbed photon. It is thought that CM is facilitated because there are interface associated states that reduce carrier cooling. Non-Adiabatic Molecular Dynamics (NAMD) simulations show that this hypothesis is correct and PbSe/CdSe carrier cooling is about two times slower compared to PbS/CdS due to weaker coupling to optical phonons.
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Lini, Matilde. "Optoelectronic characterization of hybrid organic-inorganic halide perovskites for solar cell and X-ray detector applications". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23213/.
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In the last 10 years, the research interest has been drawn towards the hybrid organic-inorganic halide perovskites, an innovative material characterized by remarkable optoelectronic properties and by its simplicity of fabrication; hybrid halide perovskites are currently being employed as active material in solar cells, X-ray photodetectors and light emitting devices.
The following thesis presents the characterization of two perovskite-based materials. The first is a methylammonium lead iodide (MAPbI3) thin film solar cell, which has been
fabricated and characterized at the University of Konstanz (Germany), with the aim to optimize the deposition procedure. The second material is a methylammonium lead bromide (MAPbBr3) single crystal that have been characterized at the University of
Bologna with surface photovoltage and photocurrent spectroscopies, as a function of the deposited dose of X-rays in order to monitor the induced effects of radiation.
After the exposure to X-rays, the exciton binding energy, calculated from the surface photovoltage spectra, has been found to increase by 20 meV with respect to the not irradiated sample. A similar result has been found with the photocurrent spectroscopy. The reasons for the increase in binding energy is discussed and attributed to a change in polarizability of the single crystal. The recovery of the crystals has been registered as well and has shown that the material is able to return to the initial condition after just few hours from the last X-ray's deposition.
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Liu, Tianyu. "Perovskite Solar Cells fabrication and Azobenzene Perovskite synthesis: a study in understanding organic-inorganic hybrid lead halide perovskite". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1576840261464488.
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Safdari, Majid. "Chemical Structure and Physical Properties of Organic-Inorganic Metal Halide Materials for Solid State Solar Cells". Doctoral thesis, KTH, Tillämpad fysikalisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199951.
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Abstract Methylammonium lead (II) iodide has recently attracted considerable interest which may lead to substantial developments of efficient and inexpensive industrial photovoltaics. The application of this material as a light-absorbing layer in solid-state solar cells leads to impressive efficiency of over 22% in laboratory devices. However, for industrial applications, fundamental issues regarding their thermal and moisture stability need to be addressed. MAPbI3 belongs to the perovskite family of materials with the general formula ABX3 ,where is the organic cation (methylammonium) which is reported to be a major source of instability. In this work, a variety of alkyammonium lead (II) iodide materials have been synthesized by changing the organic cation, to study the relationship between the structural and physical properties of these materials. [(A)PbI3] and (A)PbI4 series were studied. Three dimensional (3D) networks (MAPbI3,MAPbBr3), two dimensional (2D) layered systems (BdAPbI4, HdAPbI4, OdAPbI4), and one dimensional (1D) columns (EAPbI3, PAPbI3, EAPb2I6) were found for the materials. [PbI6] octahedral structural units were repeated through the material network depending on the dimensionality and connectivity of the materials. Where a bulkier cation was introduced, the crystallographic unit cell increased in size which resulted in lower symmetry crystals. The connectivity of the unit cells along the material networks was found to be based on corner-sharing and face-sharing. Lower dimensionality resulted in larger bandgaps and lower photoconductivity, and hence a lower light conversion efficiency for the related solar cells. The thermal and moisture stability was greater in the 1D and 2D materials with bulkier organic cations than with methylammonium. In total, an overview is provided of the relationship between the chemical dimensionality and physical properties of the organic-inorganic lead halide materials with focus on the solar cell application.Svenska sammandrag: Metylammoniumbly(II)jodid har under de senaste åren genererat ett stort intresse som ett möjligt material for utveckling av effektiva och på industriell skala billiga solceller. Detta material har använts som ljusabsorberande skikt i fasta solceller med imponerande omvandlingseffektiviteter på över 22% för solceller i laboratorieskala. För att denna nya typ av solceller ska bli intressanta för produktion på industriell skala, så behöver grundläggande frågeställningar kring materialens stabilitet avseende högre temperaturer och fukt klargöras. MAPbI3 har formellt perovskitstruktur med den allmänna formel ABX3, där A utgörs av den organiska katjonen (metyammoniumjonen) och som kan kopplas till materialets instabilitet. I denna avhandling har olika alkylammoniumbly(II)jodidmaterial syntetiserats där den organiska katjonen modifierats med syftet att studera växelverkan mellan struktur och fysikaliska egenskaper hos de resulterande materialen. Material av olika dimensionalitet erhölls; tredimensionella (3D) nätverk (MAPbI3, MAPbBr3), tvådimensionella (2D) skiktade strukturer (BdAPbI4, HdAPbI4, OdAPbI4), och endimensionella (1D) kedjestrukturer (EAPbI3, PAPbI3, EAPb2I6). Flera nya lågdimensionella material (2D och 1D) tillverkats och karaktäriserats för första gången. Enkristalldiffraktometri har använts för att erhålla materialens atomära struktur. Strukturen hos material tillverkade i större mängder konfirmerades genom jämförelse mellan resultat från pulverdiffraktion och enkristalldiffraktion. Den oktaedriska strukturenheten [PbI6] utgör ett återkommande tema i materialen sammankopplade till olika dimensioner. Då större organiska katjoner används karaktäriseras i regel strukturerna av större enhetsceller och lägre symmetri. De lågdimensionella materialen ger typiskt störe elektroniskt bandgap, lägre fotoinducerad ledningsförmåga och därför sämre omvandlingseffektiviteter då de används i solceller. De lågdimensionella materialen (1D och 2D) som baseras på de större organiska katjonerna uppvisar bättre stabilitet med avseende på högre tempereratur och fukt. De tvådimensionella materialens elektroniska struktur har karaktäriserats med hjälp av röntegenfotoelektronspektroskopi, liksom röntgenabsorptions- och emissionsspektroskopi. Resultat från teoretiska beräkningar stämmer väl överens med de experimentella resultaten, och de visar att materialens valensband huvudsakligen består av bidrag från atomorbitaler hos jod, medan atomorbitaler från bly främst bidrar till edningsbandet. Sammantaget erbjuder avhandlingen en översikt av sambandet mellan kemisk dimensionalitet och fysikaliska egenskaper hos ett antal organiska/oorganiska blyhalogenidmaterial med fokus på tillämpning i solceller.
QC 20170123
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Eckhardt, Kai, Volodymyr Bon, Jürgen Getzschmann, Julia Grothe, Florian M. Wisser y Stefan Kaskel. "Crystallographic insights into (CH3NH3)3(Bi2I9): a new lead-free hybrid organic–inorganic material as a potential absorber for photovoltaics". Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30174.
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The crystal structure of a new bismuth-based light-absorbing material for the application in solar cells was determined by single crystal X-ray diffraction for the first time. (CH3NH3)3(Bi2I9) (MBI) is a promising alternative to recently rapidly progressing hybrid organic–inorganic perovskites due to the higher tolerance against water and low toxicity. Single crystal X-ray diffraction provides detailed structural information as an essential prerequisite to gain a fundamental understanding of structure property relationships, while powder diffraction studies demonstrate a high degree of crystallinity in thin films.
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Eckhardt, Kai, Volodymyr Bon, Jürgen Getzschmann, Julia Grothe, Florian M. Wisser y Stefan Kaskel. "Crystallographic insights into (CH3NH3)3(Bi2I9): a new lead-free hybrid organic–inorganic material as a potential absorber for photovoltaics". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-219347.
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The crystal structure of a new bismuth-based light-absorbing material for the application in solar cells was determined by single crystal X-ray diffraction for the first time. (CH3NH3)3(Bi2I9) (MBI) is a promising alternative to recently rapidly progressing hybrid organic–inorganic perovskites due to the higher tolerance against water and low toxicity. Single crystal X-ray diffraction provides detailed structural information as an essential prerequisite to gain a fundamental understanding of structure property relationships, while powder diffraction studies demonstrate a high degree of crystallinity in thin films.
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Pasco, Hélène. "When 19th century painters prepared organic-inorganic hybrid gels : physico-chemical study of « gumtions »". Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS296.pdf.
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Les médiums étaient utilisés par les peintres afin de modifier la texture et le séchage de leur peinture. Au 19ème siècle, des artistes britanniques ont développé un médium composé d’huile siccative, de résine mastic et d’acétate de plomb trihydraté : le « gumtion ». Ce matériau de type gel surpasse les additifs alors existants. Dans cette thèse, nous contribuons à la compréhension des processus chimiques impliqués dans la formation et le vieillissement des gumtions. Dans un premier temps, nous avons centré l’étude sur la résine mastic, car il s’agit d’un élément clé dans la préparation des gels. La fraction triterpénique de la résine a été identifiée et quantifiée par GC/MS. De plus, nous avons étudié par ellipsométrie les propriétés optiques de vernis sous forme de films minces, ainsi que leur comportement (gonflement) sous différentes atmosphères. Puis, en reproduisant des recettes historiques et afin d’approfondir la compréhension des interactions chimiques entre les composants du gel, nous avons développé des formulations simplifiées à base d’acide oléanolique (triterpène commercial) et d’un composé de plomb (acétate ou oxyde). L’utilisation de techniques d’analyses complémentaires aux échelles moléculaire (IR, MAS-RMN) et supramoléculaire (cryo-TEM, SAXS) indique dans un premier temps la formation d’un complexe de coordination entre le plomb et les fonctions acides des triterpénoïdes, qui s’arrangent en objets 2D expliquant le comportement viscoélastique du matériau. Après plusieurs mois de vieillissement, nous avons observé l’auto-organisation de nanoparticules cristallines en en lamelles, témoignant du caractère dynamique de ce matériau même avec gélificationMediums were used by painters in order to modify the texture and drying properties of their paint. During the 19th century, British artists developed a particular medium made of siccative oil, mastic resin and lead acetate trihydrate. The so-called “gumtions” form gel-like materials in a relatively short time, outperforming the existing paint media. This thesis contributes unveiling the chemical processes involved in the formation and ageing of gumtions. As a first step, we focused on mastic resin since it is a key component for the preparation of gumtion. The triterpenic fraction of the resin was identified and quantified using GC and GC/MS. Moreover, we took advantage of Spectroscopic Ellipsometry so as to study the optical properties of varnish thin films as well as their behaviour (swelling) under various atmospheres. Then, we reproduced historical recipes that helped us afterwards to define simplified formulations to deepen the understanding of the chemical interactions between the gel components, made of oleanolic acid (commercial triterpenoid) and a lead compound (acetate or oxide). They were investigated at dierent scales by spectroscopic (FTIR, MASNMR) and supramolecular analyses (Cryo-TEM, SAXS). The use of these complementary techniques gives an overview of the gel’s structure and formation: rapidly, a coordination complex is formed between lead and the carboxylic acid moieties of the triterpenoids, that organizeinto2Dobjectsleadingtothesolid-likebehaviorofthematerial. After few months ageing, we observed the self-assembly of crystalline nanoparticles into lamellar structures, witnessing the dynamic occurring in the material even after gelation.bly of crystalline nanoparticles into lamellar structures, witnessing the dynamic occurring in the material even after gelation
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Mabiala, Floyd Lionel. "Photo-physical properties of lead-tin binary Perovskite thin films". University of Western Cape, 2021. http://hdl.handle.net/11394/8002.
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>Magister Scientiae - MScOrganic-inorganic lead-based perovskite has exhibited great performance in the past few years. However, the lead (Pb) embedded in those compounds is a significant drawback to further progress, due to its environmental toxicity. As an alternative, tin (Sn) based-perovskites have demonstrated promising results in terms of electrical and optical properties for photovoltaic devices, but the oxidation of tin ion- from stannous ion (Sn2+) to stannic ion (Sn4+) presents a problem in terms of performance and stability when exposed to ambient conditions. A more feasible approach may be in a Pb-Sn binary metal perovskite in pursuit of efficient, stable perovskite solar cells (PSCs) with reduced Pb-content, as compared to pure Pb- or Sn-based PSCs. Here, we report on the deposition of a Pb-Sn binary perovskite by sequential chemical vapor deposition.
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Ralaiarisoa, Maryline. "Electronic properties of hybrid organic-inorganic perovskite films: effects of composition and environment". Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20194.
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Der Schwerpunkt der vorliegenden Arbeit liegt in der Charakterisierung der elektronischen Eigenschaften von hybriden organisch-anorganischen Perowskit (HOIP)-Schichten während der Schichtbildung und in verschiedenen Umgebungen mittels Photoelektronenspektroskopie (PES). Insbesondere wird der Methylammonium-Blei-Iodid-Chlorid-Perowskit (MAPbI3-xClx) untersucht.
Als erstes werden Änderungen in den elektronischen Eigenschaften, der Zusammensetzung, sowie der Kristallstruktur mittels PES, Flugzeit-Sekundärionenmassenspektrometrie, sowie Röntgendiffraktometrie mit streifendem Einfall analysiert. Die Resultate weisen auf die entscheidende Rolle von Chlor im texturierten Wachstum der Perowskitschicht hin. Die auskristallisierte Perowskitschicht weist eine stärkere n-Typ Eigenschaft auf, welche auf die Änderung der Zusammensetzung während der Schichtbildung zurückgeführt werden kann. Außerdem beweisen die Ergebnisse eindeutig die Ablagerung von Chlor an der Grenzfläche zwischen der Perowskitschicht und dem Substrat. Zweitens werden die separaten Einflüsse von Wasser, Sauerstoff, und Umgebungsluft auf die elektronischen Eigenschaften von MAPbI3-xClx-Schichtoberflächen untersucht. Bereits geringste Wassermengen ähnlich wie im Hochvakuum oder in inerter Umgebung können eine reversible Reduzierung der Austrittsarbeit hervorrufen. Höherer Wasserdampf-Partialdruck führt zu einer Verschiebung des Valenzbandmaximums (VBM) weit vom Fermi-Niveau, sowie zu einer Reduzierung der Austrittsarbeit. Im Gegensatz dazu führt eine Sauerstoffexposition zu einer Verschiebung des VBM in Richtung des Fermi-Niveaus und zu einer Steigerung der Austrittsarbeit. Analog kommt es zu einer Verschiebung von bis zu 0.6 eV bei einer Exposition gegenüber Umgebungsluft, was den vorwiegenden Einfluss von Sauerstoff demonstriert.
Die vorliegenden Untersuchungen betonen den kritischen Einfluss der Schichtbildung, der Zusammensetzung, sowie der Umgebungsbedingungen auf die elektronischen Eigenschaften von HOIP.The present thesis aims at characterizing the electronic properties of solution-processed hybrid organic-inorganic perovskites (HOIPs) in general, and the HOIP methyl ammonium (MA) lead iodide-chloride (MAPbI3-xClx) films, in particular, at different stages, namely from its formation to its degradation, by means of photoelectron spectroscopy (PES). Firstly, the formation of MAPbI3-xClx films upon thermal annealing is monitored by a combination of PES, time-of-flight secondary ion mass spectrometry, and grazing incidence X-ray diffraction for disclosing changes in electronic properties, film composition, and crystal structure, respectively. Overall, the results point to the essential mediating role of chlorine in the formation of a highly textured perovskite film. The film formation is accompanied by a change of composition which leads to the film becoming more n-type. The accumulation of chlorine at the interface between perovskite and the underlying substrate is also unambiguously revealed. Secondly, the separate effects of water and oxygen on the electronic properties of MAPbI3-xClx film surfaces are investigated by PES. Already low water exposure – as encountered in high vacuum or inert conditions – appears to reversibly impact the work function of the film surfaces. Water vapor in the mbar range induces a shift of the valence band maximum (VBM) away from the Fermi level accompanied by a decrease of the work function. In contrast, oxygen leads to a VBM shift towards the Fermi level and a concomitant increase of the work function. The effect of oxygen is found to predominate in ambient air with an associated shift of the energy levels by up to 0.6 eV. Overall, the findings contribute to an improved understanding of the structure-property relationships of HOIPs and emphasize the impact of least variation in the environmental conditions on the reproducibility of the electronic properties of perovskite materials.
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Bogner, Lea [Verfasser]. "Ultrafast Relaxation Dynamics after Optical Excitation of Hybrid Inorganic/Organic Systems / Lea Bogner". Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1080171215/34.
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Omondi, Celline Awino [Verfasser], Bernd [Gutachter] Rech, Roland [Gutachter] Scheer y Thomas [Gutachter] Dittrich. "Investigation of hybrid organic-inorganic lead halide perovskites by modulated surface photovoltage spectroscopy / Celline Awino Omondi ; Gutachter: Bernd Rech, Roland Scheer, Thomas Dittrich". Berlin : Technische Universität Berlin, 2018. http://d-nb.info/1164498150/34.
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Rathod, Siddharth Narendrakumar. "Structure Stability and Optical Response of Lead Halide Hybrid Perovskite Photovoltaic Materials: A First-Principles Simulation Study". Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496189488934021.
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Lubuna, Beegum Shafeek. "Organic-Inorganic Hetero Junction White Light Emitting Diode : N-type ZnO and P-type conjugated polymer". Thesis, Linköping University, Department of Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11195.
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The purpose of this thesis work is to design and fabricates organic-inorganic hetero junction White Light Emitting Diode (WLED). In this WLED, inorganic material is n- type ZnO and organic material is p-type conjugated polymer. The first task was to synthesise vertically aligned ZnO nano-rods on glass as well as on plastic substrates using aqueous chemical growth method at a low temperature. The second task was to find out the proper p- type organic material that gives cheap and high efficient WLED operation. The proposed polymer shouldn’t create a high barrier potential across the interface and also it should block electrons entering into the polymer. To optimize the efficiency of WLED; charge injection, charge transport and charge recombination must be considered. The hetero junction organic-inorganic structures have to be engineered very carefully in order to obtain the desired light emission. The layered structure is composed of p-polymer/n-ZnO and the recombination has been desired to occur at the ZnO layer in order to obtain white light emission. Electrical characterization of the devices was carried out to test the rectifying properties of the hetero junction diodes.
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Solontsi, Mhlangabezi. "The response of maize to selected ratios of organic fertilizers mixed with inorganic fertilizers in Ndlambe Local Municipality, Eastern Cape, South Africa". Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020902.
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The majority of small-scale farmers in the Eastern Cape apply inadequate quantities of manure, inorganic (NPK) fertilizer and Gromor as lone fertilizers or tend to mix manure or Gromor with chemical fertilizers for crops, without any scientific basis (Mkile, 2001). Hence this study – aimed at achieving effective and efficient use of chemical fertilizers, manure and Gromor, either as lone fertilizers or mixed with one another, in maize production – was established. A three-year dry land field experiment, arranged in a RCBD with 3 replicates where cattle manure, chemical fertilizer and Gromor were mixed at different ratios – as treatments FM1 (10 percent fertilizer + 90 percent manure); FM2 (25 percent fertilizer + 75 percent manure); FM3 (50 percent fertilizer + 50 percent manure); MAP (100 percent fertilizer); M (100 percent cattle manure); FG1 (10 percent fertilizer + 90 percent Gromor); FG2 (25 percent fertilizer + 75 percent Gromor); FG3 (50 percent fertilizer + 50 percent Gromor); G (100 percent Gromor) and a control (with nothing applied) – was conducted at the Nolukhanyo agricultural project at Bathurst in the Ndlambe Local Municipality. Maize cultivars PAN 6480 and Sahara were used as test crops. Manure, Gromor and soil were analyzed for their nutrient composition. Data recorded involving number of kernels per cob-1, grain and dry matter (DM) yields for the 2010-11, 2011-12 and 2012-13 seasons, and leaf area index (LAI) – were subjected to Genstat Version 14.1 for statistical analysis. Grain yields of PAN 6480 and Sahara recorded in seasons 2010-11, 2011-12 and 2012-13 were significantly higher (p≤0.05) than those of the controls. In 2012-13, PAN 6480 on treatments FG3 and FG1 produced the highest grain yields (5 327 and 5 107kg ha-1) respectively, while in 2010-11 the highest yield was 3 780kg ha-1. In the 2012-13 season, Sahara on F treatment was the highest with 4 553kg ha-1 whilst there were no significant differences in F and M treatments. Dry matter yields of Sahara were higher than those of PAN 6480 in all seasons. The highest Sahara LAI obtained on FM2 was 5.85 in the 2012-13 season, whereas PAN 6480 had LAI of 4.77 on F treatment, followed by FG3 with 4.72 LAI. PAN 6480 number of leaves for 6 plants in m2 and LAI in week 8 of the 2012-13 season had a positive correlation, r2=0.84. PAN 6480 number of kernels and cob length in the same area correlated quite well (r2 =0.91). Chemical fertilizer corrects the imbalances of nutrients inherent in organic manures and increases both maize grain yields and dry matter yields, and also influences number of leaves and LAI. Treatments FG1, FG3 and FM1 of PAN 6480 resulted in high maize grain yields when planted 13 in late November of the 2012-13 growing season and when water in the soil profile was conserved as a result of good rains received prior to planting. Treatments FG1 (10 percent fertilizer + 90 percent Gromor), FG3 (50 percent fertilizer + 50 percent Gromor) of PAN 6480 produced the highest grain yields (5 107kg ha-1 and 5 327kg ha-1 respectively) in the 2012-13 season, whilst FM1 (10 percent fertilizer + 90 percent manure) gave the highest grain yield (of 4 277kg ha-1) for the same cultivar in the 2010-11 season.
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Jönsson, Jörgen. "Phase transformation and surface chemistry of secondary iron minerals formed from acid mine drainage". Doctoral thesis, Umeå University, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-156.
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The mining of sulphidic ore to extract metals such as zinc and copper produces huge quantities of waste material. The weathering and oxidation of the waste produces what is commonly known as Acid Mine Drainage (AMD), a dilute sulphuric acid rich in Fe(II) and heavy metals. This thesis serves to summarise five papers reporting how the precipitation of Fe(III) phases can attenuate the contamination of heavy metals by adsorption processes.
Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III) mineral precipitating in AMD environments at pH 3-4. The stability and surface chemistry of this mineral was investigated. It was shown that the stability depended strongly on pH and temperature, an increase in either promoted transformation to goethite (α-FeOOH). Two pH dependent surface species of SO42- were detected with infrared (ATR-FTIR) spectroscopy.
The adsorption of Cu(II), Pb(II) and Zn(II) to schwertmannite occurred at lower pH than to goethite, whereas Cd(II) adsorption occurred in a similar pH range on both schwertmannite and goethite. Extended x-ray absorption fine structure (EXAFS) spectroscopy suggests two surface species for Cu(II) and Cd(II) at the schwertmannite surface. Cu(II) adsorbs monodentately and Cd(II) bridging bidentately to adsorbed SO42-. Both metal ions also adsorb in a bridging bidentate mode to the surface hydroxyl groups. At pH 7.5 up to 2.7 μmol Cd(II) m-2 could be adsorbed to schwertmannite, indicating a large adsorption capacity for this mineral.
The acid-base properties of two NOM samples were characterised and could be well described as diprotic acids below pH 6. The adsorption of NOM to schwertmannite and goethite was very similar and adsorption occured in a very wide pH range.
High concentrations of NOM increased the adsorption of Cu(II) to goethite at low pH whereas a slight decrease was noted at low concentrations of NOM. No effect was detected in the schwertmannite system.
The formation of Fe(III) phases from precipitation of AMD was shown to be very pH dependent. At pH 5.5 a mixture of minerals, including schwertmannite, formed whereas at pH 7 only lepidocrocite (γ-FeOOH) formed. The concentration of Zn(II) in AMD could by adsorption/coprecipitation be reduced to environmentally acceptable levels.
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Aversa, Pierfrancesco. "Primary Defects in Halide Perovskites : Effect on Stability and Performance for Photovoltaic Applications Effect of organic PCBM Electron transport Layers on natural and post-irradiation ageing of optical absorption and emission in methyl ammonium lead triiodide spin –coated on p-i-n Solar Sell Substrates Effect of organic PCBM Electron transport Layers on natural and post-irradiation ageing of optical absorption and emission in triple cation lead mixed halide perovskite spin –coated on p-i-n Solar Sell Substrates Electron Irradiation Induced Ageing Effects on Radiative Recombination Properties of methylammonium lead triiodide layers on p-i-n solar cell substrates Electron Irradiation Induced Ageing Effects on Methylammonium Lead Triiodide Based p-i-n Solar Cells Electron Irradiation Induced Ageing Effects on Radiative Recombination Properties of Quadruple Cation Organic-Inorganic Perovskite Layers". Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX050.
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Ces onze dernières années ont vu apparaitre les pérovskites organiques inorganiques hybrides (HOIPs) comme un passionnant domaine de recherche pour leur application potentielle dans les technologies du photovoltaïque (PV) en raison de leurs exceptionnelles propriétés optoélectroniques et de leur facilité de mise en oeuvre. Cependant, les matériaux HOIPs ont plusieurs inconvénients dont leur manque de stabilité en conditions opérationnelles. Améliorer celle-ci est l'un des plus grands défis à relever avant commercialisation. La formule générale est (A1,A2,A3,A4)Pb(X1,X2)3, où les sites A occupés par une distribution de 1 à 4 cations métalliques/organiques et les sites X par celle d’anions halogénures. Les défauts lacunaires natifs sont considérés comme une cause possible de dégradation des cellules solaires HOIPs. L'objectif de ce travail est de comprendre le rôle des défauts dans la stabilité à long terme des matériaux PV HOIPs. A cette fin, des défauts primaires ont été introduits de manière contrôlée par irradiation avec des électrons de haute énergie (1MeV) dans des lots de couches et cellules solaires (SCs) à base de divers composés HOIPs. Il s'agit notamment du prototype PV HOIPs, MAPbI3 (A1PbX13), et de nouveaux composés mixtes d’halogénures à triple ou quadruple cations, (CsMAFA)Pb(I1-xBrx)3 (A3PbX23) ou (GACsMAFA)Pb(I1-yBry)3 (A4PbX23). Les couches sont fabriquées selon la même procédure que les couches actives SCs et, ensuite, traitées dans des conditions similaires. Pour A1PbX13/A3PbX23, la structure SC est de type p-i-n avec des couches organiques pour le transport des trous et des électrons (HTL/ETL). Les couches sont déposées sur le substrat verre/ITO/HTL (PEDOT:PSS) sans ou avec couche supérieure ETL (PCBM). Pour A4PbX23, la structure SC est de type n-i-p avec des couches ETL inorganiques (TiO2) et HTL organiques (Spiro-OMeTAD). Les couches sont directement déposées sur du verre.La spectroscopie d'annihilation de positons donne une évidence directe de l'existence de défauts lacunaires natifs et induits par irradiation dans chaque composé. Les spectres d’absorbance en fonction de l’énergie montrent que le vieillissement naturel et après irradiation génère différentes populations de défauts dans chaque composé. De plus, celles-ci pour A1PbX13 et A3PbX23 diffèrent selon l'absence ou la présence de la couche supérieure ETL. Les populations de défauts évoluent pendant au moins 3 mois. Le vieillissement modifie (i) la bande interdite, (ii) les queues de bande de conduction/valence et (iii) l'absorption optique via des niveaux électroniques profonds. Les effets d’illumination sous laser varient aussi en fonction du vieillissement. L’asymétrie des pics de photoluminescence (PL) dans chaque composé sous illumination laser continue reflète une superposition de raies d’émission gaussiennes à énergie, FWHM et hauteur évoluant avec le temps d'illumination. Les transitions d'émission impliquent des niveaux électroniques localisés peu profonds dans A3PbX23/A4PbX23 et résonnants dans A1PbX13. De tels effets durent au moins 3 mois dans A4PbX23. Ces niveaux électroniques sont attribués à des populations de défauts spécifiquement induits par illumination. Le vieillissement naturel et après irradiation donne des spectres PL à décroissance temporelle résolue en une ou deux exponentielles. Le nombre et la durée de vie sont fortement influencés par l’irradiation initiale et la composition. Une amélioration frappante du fonctionnement PV pour le type SC p-i-n est induite par le vieillissement dû à l'irradiation. Le rendement quantique externe et les performances PVs ont des valeurs plus élevées pour l’état irradié que de référence durant 6 à 12 mois de vieillissement. Cela prouve que l'ingénierie des défauts par irradiation d'électrons à haute énergie a le potentiel de fournir des voies de traitement innovantes pour améliorer la stabilité à long terme des performances photovoltaïques HOIPsDuring the last eleven years, Hybrid Organic Inorganic Perovskites (HOIPs) materials have emerged as an exciting topic of research for potential application in solar cell technologies due to their outstanding optoelectronic properties and processing advantages. However, HOIPs materials suffer from several drawbacks with, in peculiar, their lack of stability under operational conditions (light, bias, environment…). To improve this stability is one of the biggest challenges to be addressed before commercialization. The general formula for HOIPs is (A1,A2,A3,A4)Pb(X1,X2)3, where the A sites can be occupied by a distribution of 1 to 4 metallic/organic cations and X sites with halide anions. The role of native vacancy defects has been questioned as a possible cause for HOIPs solar cells degradation. The aim of this work is to understand the defect role in long term stability of HOIPs materials for photovoltaics. For this reason, primary defects were introduced in a controlled way via high energy electron irradiation (1MeV) in sets of layers and solar cells (SCs) fabricated using various HOIPs compounds. Those include the photovoltaic HOIPs prototype, MAPbI3 (A1PbX13), and emergent triple or quadruple cation mixed halide HOIPs, (CsMAFA)Pb(I1-xBrx)3 (A3PbX23) or (GACsMAFA)Pb(I1-yBry)3 (A4PbX23). The HOIPs layers are fabricated according to the same procedure as the HOIPs active SC layers and, subsequently, treated in similar conditions. For A1PbX13 and A3PbX23, the solar cells are of the p-i-n structure with organic hole and electron transport layer (HTL/ETL). The HOIPs layers are deposited on the glass/ITO/HTL (PEDOT:PSS) substrate without or with the top ETL layer (PCBM). For A4PbX23, the solar cells are of the n-i-p type with inorganic ETL (TiO2) and organic HTL (Spiro-OMeTAD) layers. The layers are directly deposited on glass without the ETL layer.Positron Annihilation Spectroscopy (PAS) gives direct evidence for native vacancy-type defects and irradiation induced ones in layers of each HOIP compound. The energy dependence of absorbance shows that natural and after irradiation ageing generates different defect populations in each HOIP compound. These populations strikingly also differ depending on the absence or presence of the top ETL layer for the A1PbX13 and A3PbX23 compounds. The defect populations evolve over ageing duration as long as 3 months. The prominent effects of ageing include (i) band gap modification, (ii) tailing of conduction/valence band extrema and (iii) optical absorption via deep subgap electronic levels. Illumination effects under laser also vary with ageing for each HOIP compound. Asymmetric photoluminescence (PL) peaks in each compound under continuous laser illumination reflect that radiative emission involves Gaussian emission rays with energy, FWHM and height evolving with illumination time. The emission transitions involve shallow localized electronic levels in A3PbX23 and A4PbX23 and resonant ones in A1PbX13. These electronic levels are attributed to specifically illumination-induced defect populations. Natural and after irradiation ageing result in PL decay lifetime spectra resolved into one or two exponential decay components. The decay components number and lifetime are strongly affected by the initial production of irradiation defects and HOIPs composition. Such effects last over 3 months at least in A4PbX23. The p-i-n solar cells exhibit most striking irradiation ageing induced photovoltaics performance. The External Quantum Efficiency (EQE versus photon energy) and the photovoltaic performance (I-V under illumination) of the irradiated solar cells have higher values than those in the reference SCs after 6 to 12 months of ageing. This gives evidence that defect engineering via high energy electron irradiation has a potential for providing innovative processing pathways to enhance the long-term stability of HOIPs photovoltaic performance
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Kyriazi, Eleni. "Inorganic/organic hybrid polymers". Thesis, University of Greenwich, 2005. http://gala.gre.ac.uk/6214/.
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The aims of this project were to synthesise and characterise a range of inorganic/organic hybrid polymers containing pendant vinyl groups and to study their uses as possible fire retardants. The work consisted of several parallel strands: the synthesis of organically modified silicas; the preparation of vinyl containing silsesquioxanes based on the hydrolysis of cyclohexyltrichlorosilane or propylmethacrylatepolysiloxane; the synthesis of latexes by co-polymerisation of either N-Isopropylacrylamide (NIPAM) or styrene with vinyltrimethoxysilane and the intercalation of styrene or NIPAM into montmorillonite. All samples were characterised using a range of instrumental techniques including infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), X-ray diffraction (XRD), elemental analysis, thermal analysis, surface area analysis and electrokinetic analysis. Vinyl modified silicas having large surface areas (about 400m2g-1) were successfully obtained. On calcining at 540°C silicas having surface area in excess of 1000m2g-1 were formed. Both the original organically modified silica and a sample after calcining were incorporated into poly(methylmethacrylate) and these samples were compared with pure poly(methymethacrylate) in a cone calorimeter to study their thermal properties. No significant enhancement to the thermal stability of the polymers was observed when the silica was incorporated. Analysis of the co-polymer latexes were inconclusive, in the case of the products obtained from NIPAM but particles having a narrow size distribution were obtained using styrene. There was no apparent trend in the value of the zeta potential with composition. Analysis of the intercalation of monomers into clays and the synthesis of silsesquioxanes were inconclusive.
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Oey, Ching-ching. "Organic-inorganic nanocomposites for organic optoelectronic devices". Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B35321222.
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Oey, Ching-ching y 黃晶晶. "Organic-inorganic nanocomposites for organic optoelectronic devices". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B35321222.
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Otsuka, Takeshi. "Functionalization of Organic-Inorganic Nano-Hybrids Utilizing Inorganic Nanoparticles". 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126813.
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Sgraja, Martin [Verfasser]. "Template based synthesis of organic, inorganic and organic-inorganic hybrid hollow spheres / Martin Sgraja". Aachen : Shaker, 2011. http://d-nb.info/1070151971/34.
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Sellner, Stefan. "Organic inorganic interfaces for applications in organic electronics". [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-25843.
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D'Elia, Eleonora. "Self-healing organic/inorganic composites". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/42229.
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Nature provides us with amazingly complex and clever systems, structures and substances that make up the world we see around us. We can refer to nature, borrowing its ingenious solutions to solve engineering challenges or improve existing man-made materials. The process of assimilating real- world biological examples into technology is called 'bio-inspiration', and for many years scientists have been attempting to imitate the design of natural materials. This project seeks to mimic some of the complex architectures with outstanding properties found in nature: the shells of molluscs, with extraordinary toughness due to a highly hierarchical structure of platelets on the micro- and nano- scale, and human bone, with its ability to self-heal and regenerate its complex composite organic/inorganic microstructure after fracture. In this work it will therefore be investigated the effect of composite polymer/ceramic structures obtained via a manufacturing technique called freeze-casting, it is observed and optimised the role of the thin interface in self-healing organic/inorganic composites and the composition of the soft supramolecular phase and the inorganic phase is varied in order to obtain structures with properties closer to the behaviour of natural ones. The study couples interface and composite design with mechanical tests to determine interfacial adhesion in order to understand the factors that control the strength of the composite and the effectiveness and timescale of its self-healing. The same self-healing polymer is moreover used in the production of an innovative light composite exhibiting electrical conductivity and compression and flexion sensing capabilities in the attempt to mimic the outstanding properties of skin.
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Gao, Tongzhai. "Anticorrosive Organic/Inorganic Hybrid Coatings". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1412775013.
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Nobre, Sónia de Sousa. "Photoluminescent nanostructured organic/inorganic hybrids". Doctoral thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2686.
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Doutoramento em FísicaO presente trabalho propõe-se caracterizar a estrutura e as propriedades de fotoluminescência de materiais híbridos orgânicos/inorgânicos. A origem química e fotofísica subjacente à emissão de luz branca dos diureiasils, híbridos compostos por uma rede siliciosa ligada covalentemente por pontes ureia a cadeias poliméricas, foi estudada fazendo uso de dois compostos modelo que reproduzem, selectivamente, as componentes orgânica e inorgânica daquela rede híbrida. A emissão nos di-ureiasils resulta da convolução de uma componente originada nos grupos ureia com uma outra proveniente dos domínios siliciosos. A comparação entre os tempos de vida das emissões dos compostos modelo com as do híbrido, a dependência do tempo de vida destas emissões com a temperatura e a variação da curva de decaimento associada à emissão dos grupos ureia com o tempo de atraso entre o final da excitação e o início da medida, suportam a ocorrência de transferência de energia entre a componente originada nos domínios siliciosos e a proveniente dos grupos ureia. A taxa de transferência de energia foi quantitativamente estimada considerando os mecanismos de troca (3.7×108 s- 1 ) e dipolo-dipolo (1.3×109 s-1). Esta taxa foi, também, calculada para um diureiasil incorporando um complexo de Eu3+ tendo-se verificado que o canal mais eficiente para a luminescência é: (S0) Híbrido → (T) Híbrido → (T) Ligando → (5D1, 5D0) → 7 F0-4. Um precursor híbrido com cadeias alquílicas e grupos ureia (P12), preparado por catálise àcida ou nucleofílica, deu origem, respectivamente, a uma estrutura lamelar cristalina (L12) e a um material amorfo (A12). Iões Eu3+ foram incorporados nos dois sistemas. Para os híbridos obtidos por catálise nucleofílica, demonstrou-se que a sua morfologia é fortemente determinada pela presença e modos de coordenação dos iões Eu3+. Todos os híbridos são emissores de luz branca. A incorporação de iões Eu3+ diminui o rendimento quântico da rede híbrida, o que indica a existência de transferência de energia rede-iões Eu3+ . Um precursor incorporando bipiridina e grupos ureia foi preparado pelo método sol-gel através de catálise nucleofílica, dando origem a híbridos amorfos. Estes híbridos são caracterizados por uma emissão de banda larga atribuída à sobreposição de três componentes: i) estado tripleto da bipridina, recombinações electrão-lacuna originadas ii) nos grupos ureia e iii) nos domínios siliciosos. Valores de 0.18-0.22 foram obtidos para o rendimento quântico, para excitação no UV/azul. Foi demonstrado que os híbridos podem ser excitados com um LED de INGaN comercial, tornando-os materiais promissores para aplicações em fontes de luz de estado sólido. Os híbridos foram também preparados incorporando iões Eu3+, Gd3+, Tb3+ e Eu3+/Tb3+. Os materiais resultantes são emissores de luz branca onde a emissão intra 4-f dos iões lantanídeo se sobrepõe à emissão da rede híbrida.
The present work focuses on the characterization of the structural and photoluminescence (PL) properties of a series of organic/inorganic hybrids. The photophysical and chemical origin behind the white-light photoluminescent features of amide-functionalized hybrids lacking metal activators (di-ureasils) was studied making use of two model compounds that selectively reproduced the organic and inorganic counterpart parts. The comparison between the lifetimes of the two emissions of the inorganic and organic model compounds with those of the hybrids, the Arrhenius dependence with temperature of the siliceous-related lifetime in the hybrids, and the nonexponential behavior of the decay curve of the siliceous-related emission under lower excitation wavelengths are experimental evidence supporting the occurrence of energy transfer in the hybrids. This energy transfer rate is quantitatively estimated for a di-ureasil, generalizing the ideas proposed by Malta, considering the exchange (3.7×10 8 s-1) and dipole–dipole mechanisms (1.3×10 9 s-1). The energy transfer rates were also calculated for a di-ureasil incorporating a Eu3+ complex and it was found that the most efficient luminescence channel is (S 0)Hybrid → (T)Hybrid → (T)Ligand → ( 5 D 1, 5 D 0) → 7 F0-4. A di-urea cross-linked alkylsilane precursor prepared using HCl induced the formation of a crystalline lamellar structure (L12); when prepared with NH 4F an amorphous material (A12) was obtained. Eu3+ ions were incorporated in the two systems and the unique role played by the Eu3+ ions in the modulation of the morphology of Eu@A12 hybrids was for the first time demonstrated via inhibition of the growth of the siloxane network formed through sol-gel reactions and urea-mediated supramolecular self-assembly. All the hybrids are room temperature multi-wavelength emitters and the incorporation of Eu3+ into the L12 and A12 hybrids induces a decrease in the absolute emission quantum yield values, supporting the existence of hybrid-to-Eu3+ energy transfer. A di-urea cross-linked bipyridine (bpy) precursor prepared by sol-gel synthesis under nucleophilic catalysis, by TBAF and NH 4F, gave rise to amorphous hybrids (termed as H and M). They are characterized by emission spectra that consist of a broad band unequivocally ascribed to a superposition of three distinct components: i) bpy triplet state, ii) electron-hole recombinations originated in the NH/C=O groups of the urea cross-linkages and iii) siliceous nanoclusters. Quantum yield values of 0.22-0.18 were measured under excitation in the long-wavelength UV and blue spectral regions. It was demonstrated that H can be efficiently excited using a commercial LED, placing bpy-hybrids as promising materials for photonics and solid state lighting. M was also prepared in the presence of Eu3+, Gd3+, Tb3+, and Eu3+/Tb3+ and formed hybrids that are room temperature multi-wavelength emitters. This is due to the convolution of the emission arising from the hybrid's emitting centres and the Ln3+ intra-4f transitions. The emission colour is tuned across the CIE diagram depending on the Ln3+ ions and the excitation wavelength.
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Guldin, Stefan. "Inorganic nanoarchitectures by organic self assembly". Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245290.
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Yeung, Hamish Hei-Man. "Lithium-based inorganic-organic framework materials". Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244938.
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This dissertation describes research into lithium-based inorganic-organic frameworks, which has led to an increased understanding of the structural diversity and properties of these materials. The crystal structures of 11 new forms of lithium tartrate, based on chiral, racemic and meso forms of the ligand, have been discovered, including eight anhydrous isomers of dilithium tartrate, Li2(C4H4O6). An experimental and computational study of their formation behaviour and energetics has shown that both kinetic and thermodynamic conditions can be used to control their phase behaviour, and the main structural factors affecting their relative energies were found to be density and hydrogen bonding. Three crystal structures topologically identical to lithium succinate, Li2(C4H4O4), have been discovered using substituted forms of the ligand: lithium L-malate, Li2(C4H4O5), lithium methylsuccinate, Li2(C5H6O4), and lithium tetrafluorosuccinate, Li2(C4F4O4). The cell parameters and mechanical properties of these non-porous frameworks were found to depend on inter-ligand interactions and metal-ligand bond strength. The effects of different ligand substituents on the atomic structure of the binary mixed-ligand solid solution, Li2(succinate)1 x(tetrafluorosuccinate)x, and the ternary system, Li2(succinate)x(L-malate)y(methylsuccinate)z [where (x + y + z) = 1], have also been investigated. Topotactic dehydration of the ligand in lithium L-malate results in the formation of Li2(L malate)1 x(fumarate)x, suggesting a new route to mixed-ligand inorganic-organic frameworks. Investigation into frameworks based on other dicarboxylate ligands produced four structurally diverse lithium-based inorganic-organic frameworks: 2-D frameworks lithium 2,2-dimethylsuccinate, Li2(C6H8O4), and lithium hydrogen D,L-malate, LiH(C4H4O5), and 3 D frameworks lithium fumarate, Li2(C4H2O4), and its singly protonated analogue, lithium hydrogen fumarate, LiH(C4H2O4). A survey of all known lithium dicarboxylates revealed that their structural trends are a function of the ligand geometry, metal:ligand ratio and degree of solvation. The electrochemical properties of nine lithium-based inorganic-organic frameworks were investigated by impedance spectroscopy and electrochemical cycling, revealing many areas to be improved in order for them to become viable materials for battery applications, such as ligand conjugation length, particle size and lithium mobility. Overall, this work has achieved a greater understanding of lithium-based inorganic-organic frameworks, revealing insight into polymorphism, phase behaviour, energetics, topological similarity, mechanical properties, ligand solid solutions, topotactic reaction, structure control and lithium battery properties. In total, 18 new crystal structures and three mixed-ligand solid solution systems are reported. The work provides a solid platform upon which new lithium-containing inorganic-organic materials may be designed and studied.
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Spinu, Maria. "Silicon-based organic and inorganic polymers". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-02052007-081236/.
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Chen, Chih-Hsien 1977. "Hybrid organic on inorganic semiconductor heterojunction". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98949.
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Hybrid organic on inorganic semiconductor heterojunctions with a sandwich structure have been fabricated and studied using conjugated polymers. The inorganic semiconductor was n-type silicon substrate. The conjugated polymers used in this work include poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) containing polyhedral oligomeric silsesquioxanes (MEH-PPV POSS), regioregular poly(3-hexylthiophene) (RR-P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT).Current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed to characterize the devices. All the devices displayed a rectifying characteristic. Among these devices, the first ever reported PEDOT doped with BF3 on n-Si heterojunction devices showed the best performance with a rectification ratio around 5.7x105 at +/- 2 V and an ideality factor of 2.3. It is speculated that performance of the devices is inversely proportional to the potential barrier height at the organic-inorganic interface. Other results from this work also suggested that smaller energy level offset between the HOMO of the conjugated polymer and the work-function of anode metal will improve device performance. Contact resistance between the anode and polymer is large (∼MΩ range) and should be further investigated in the future.
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Almeida, Paz Filipe Alexandre. "Novel organic, inorganic and hybrid frameworks". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615859.
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HE, ZHOUYING. "ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION". University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437870016.
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Freitas, Vânia Patrícia Castro Teixeira. "Organic-inorganic hybrids for green photonics". Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17325.
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Doutoramento em FísicaThe presente work aims to synthesize new bridge silsesquioxanes organic-inorganic hybrid materials, and characterize the local structure and photoluminescence properties overlooking potential applications in the area of green photonics, namely, in solid-state lighting and luminescent solar concentrators. In this context, three distinct families of materials based on six precursors which differ in their structural organization were synthesized, i.e. precursors with structure: 1) linear where the organic component is based on malonamide group, P2-m and P4-m; 2) linear which has been added an aromatic ring whose organic part is based on amide and/or thioamida, P(UU), P(UT) and P(TT) and 3) branched which the organic component is based on amide group, t-UPTES (5000). Two organic-inorganic hybrids (M2-m e M4-m) which results from hydrolysis and condensation of the precursors P2-m e P4-m were synthetized. The role of the presence of one or two malonamide groups was studied in terms of local structure and photoluminescence properties. Three organic-inorganic hybrids H(UU), H(UT) and H(TT) based on P(UU), P(UT) and P(TT) were synthesized and structurally characterized aiming to study the role of the hydrogen bond in the self-assembling of these materials. The presence of different types of hydrogen bonds (bifurcated, linear and cyclic) induces different conformations which affect the physical properties (mechanical and optical) of the materials. Hybrids based on t-UPTES(5000) precursor were synthesized based on different synthesis strategies. Changing the concentration of HCl and water content as well as the synthesis in a controlled environment allowed the improvement of the optical properties of this system, in particular, the absolute emission quantum yield and the absorption coefficient. In addition, it were studied the recombination mechanisms responsible for the emission through the comparison between the corresponding photoluminescence properties of the organic and inorganic models. Finally, due to the structural simplicity of the precursors P2-m and P4-m, these were doped with Eu3+. The local structure of the corresponding hybrids shows local coordination between the ion and the host. Efficient materials concerning the absolute emission quantum yield values motivated the development of luminescent solar concentrators with a maximum absolute emission quantum yield of 0.600.06 and optical conversion efficiency in the absorption spectral region (300-380 nm) of 12.3%.
O presente trabalho propõe sintetizar novos materiais híbridos orgânicos-inorgânicos do tipo silsesquioxanos em ponte e caracterizar a sua estrutura e propriedades de fotoluminescência com vista a potenciais aplicações na área da fotónica sustentável, nomeadamente, iluminação de estado sólido e concentradores solares luminescentes. Neste âmbito, foram sintetizadas três famílias distintas de materiais baseados em seis precursores que diferem na sua organização estrutural, ou seja, precursores com estrutura: 1) linear onde a componente orgânica é baseada no grupo malonamida, P2-m e P4-m; 2) linear onde foi adicionado um anel aromático cuja componente orgânica é baseada em amida e/ou thioamida, P(UU), P(UT) e P(TT), e 3) tri-ramificada onde a componente orgânica é baseada no grupo amida, t-UPTES(5000). Dois híbridos orgânicos-inorgânicos (M2-m e M4-m) que resultam da hidrólise e condensação dos precursores P2-m e P4-m foram sintetizados. O papel da presença de um ou dois grupos malonamida foi estudado em termos de estrutura local e propriedades de fotoluminescência. Três híbridos orgânicos-inorganicos, H(UU), H(UT) e H(TT), baseados, respetivamente, em P(UU), P(UT) e P(TT), foram sintetizados e caracterizados estruturalmente com o objetivo de estudar o papel das ligações de hidrogénio na auto-organização destes materiais. A presença de diferentes tipos de ligações de hidrogénio (bifurcada, linear e cíclica) induz diferentes tipos de configurações que têm influência nas propriedades físicas (mecânicas e óticas) dos materiais. Híbridos baseados no precursor t-UPTES(5000) foram sintetizados tendo em conta diferentes estratégias de síntese. A variação da concentração de HCl e quantidade de água bem como a síntese em ambiente controlado permitiram melhorar as propriedades óticas deste sistema nomeadamente, o rendimento quântico absoluto e o coeficiente de absorção. Foram também discutidos, os mecanismos de recombinação responsáveis pela emissão através da comparação das propriedades de fotoluminescência observadas nos correspondentes modelos orgânicos e inorgânicos. Finalmente, devido à simplicidade estrutural os precursores P2-m e P4-m, estes foram dopados com Eu3+. A estrutura local dos correspondentes híbridos mostra coordenação local entre o ião e a matriz. Materiais eficientes do ponto de vista de rendimento quântico absoluto motivaram o desenvolvimento de concentradores solares luminescentes que apresentam rendimento quântico absoluto máximo de 0.600.06 e eficiência ótica de conversão na região espetral de absorção (300-380 nm) de 12.3 %.
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Garner, Brett William. "Multifunctional Organic-Inorganic Hybrid Nanophotonic Devices". Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc6108/.
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The emergence of optical applications, such as lasers, fiber optics, and semiconductor based sources and detectors, has created a drive for smaller and more specialized devices. Nanophotonics is an emerging field of study that encompasses the disciplines of physics, engineering, chemistry, biology, applied sciences and biomedical technology. In particular, nanophotonics explores optical processes on a nanoscale. This dissertation presents nanophotonic applications that incorporate various forms of the organic polymer N-isopropylacrylamide (NIPA) with inorganic semiconductors. This includes the material characterization of NIPA, with such techniques as ellipsometry and dynamic light scattering. Two devices were constructed incorporating the NIPA hydrogel with semiconductors. The first device comprises a PNIPAM-CdTe hybrid material. The PNIPAM is a means for the control of distances between CdTe quantum dots encapsulated within the hydrogel. Controlling the distance between the quantum dots allows for the control of resonant energy transfer between neighboring quantum dots. Whereby, providing a means for controlling the temperature dependent red-shifts in photoluminescent peaks and FWHM. Further, enhancement of photoluminescent due to increased scattering in the medium is shown as a function of temperature. The second device incorporates NIPA into a 2D photonic crystal patterned on GaAs. The refractive index change of the NIPA hydrogel as it undergoes its phase change creates a controllable mechanism for adjusting the transmittance of light frequencies through a linear defect in a photonic crystal. The NIPA infiltrated photonic crystal shows greater shifts in the bandwidth per ºC than any liquid crystal methods. This dissertation demonstrates the versatile uses of hydrogel, as a means of control in nanophotonic devices, and will likely lead to development of other hybrid applications. The development of smaller light based applications will facilitate the need to augment the devices with control mechanism and will play an increasing important role in the future.
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Garner, Brett William Neogi Arup. "Multifunctional organic-inorganic hybrid nanophotonic devices". [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-6108.
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Govani, Jayesh R. "Spectroscopic characterizations of organic/inorganic nanocomposites". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Kamitakahara, Masanobu. "Preparation of bioactive inorganic-organic hybrids". 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148834.
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Abarca, Silvia Adriana Collins. "Synthesis of hybrid organic-inorganic polymer". reponame:Repositório Institucional da UFSC, 2014. https://repositorio.ufsc.br/xmlui/handle/123456789/128961.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2014.Made available in DSpace on 2015-02-05T20:32:16Z (GMT). No. of bitstreams: 1 327776.pdf: 3247660 bytes, checksum: 13d517d802fdff4f8ec6acc18ea4c073 (MD5) Previous issue date: 2014
O desenvolvimento de novas tecnologias e equipamentos na área de engenharia exige a adaptação dos materiais hoje empregados ou criação de novas matérias primas capazes de suportar os mais diversos ambientes e condições. Durante anos a engenharia química e de materiais vem estudando os materiais inorgânicos como moléculas precursoras com o intuito de obter, após tratamento térmico, fibras ou cerâmicas de alta performance, dotadas de características químicas e térmicas inalcançáveis com outros materiais. Materiais cerâmicos são destinados à aplicações bastante nobres na área aeroespacial e automotiva devido ao elevado custo dos compostos empregados em sua obtenção.Com o objetivo de produzir materiais com características melhoradas, aumentando assim o leque de aplicações e ao mesmo tempo reduzir os custos de produção, buscou-se introduzir moléculas orgânicas ao processo de síntese. A inserção de compostos orgânicos permite a inclusão de funções orgânicas, melhora as propriedades químicas, permite o uso de menores quantidades de material inorgânico e diversifica a área de aplicações. Até o presente momento, diversos autores sintetizaram novos compostos híbridos orgânico-inorgânicos através de rotas sintéticas variadas. Neste trabalho foram utilizados precursores inorgânicos comerciais e o monômero orgânico estireno através de duas grandes rotas sintéticas, polimerização em solução via radicais livres e hidrossililação assistida por catalisador metálico com adição de iniciador radicalar.Produtos com diferentes características foram sintetizados por ambas as técnicas. Ambas as técnica utilizadas mostraram-se adequadas para a obtenção de um polímero híbrido com as características desejadas. O híbrido orgânico-inorgânico sintetizado apresentou elevada estabilidade térmica resultando em um alto grau de ceramização, caracterizando-o assim como um bom material precursor para cerâmicas.
Abstract : The development of new technologies and equipment in engineering area forces the improvement of materials used nowadays or the conception of new with capability to be applied in different environments and conditions. Along years chemical and material engineers have been studying inorganic materials as precursor molecules intending to obtain, after thermal treatment, high performance fibers and ceramics, with singular chemical and thermic characteristics obtained only by these materials. Ceramic materials are applied in noble applications like aerospace and automotive due to the high aggregate value of raw material.A promising material with improved characteristics, to increase the range of applications and decrease production costs, is the combination of organic molecules and preceramic compounds in a synthesis process. The addition of organic compounds allows the inclusion of organic functions, improves chemical properties, reduces the amount of inorganic material and diversifies the application area. Nowadays several authors have synthesized new hybrid organic - inorganic compounds by numerous synthetic routes. In this work commercial inorganic precursors and organic styrene monomer were reacted by two synthetic routes, solution polymerization with free radical initiator and hydrosilylation assisted by metal catalyst with the subsequent addition of free radical initiator.Products with different characteristics were synthesized using polymerization by free radical initiator and hydrosilylation followed by radical initiator addition. Both techniques revealed to be satisfactory to obtain a hybrid polymer with improved characteristics. The new organic-inorganic hybrid materials synthesized showed high thermal stability resulting in a high ceramic yield, characterizing it as a good precursor material for ceramics.
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Ben, Sghaier Asma. "Hybrides polymer materials organic/inorganic nanoparticule". Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1163.
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La chimie d'interface du diazonium a progressé au cours des dernières années et s'est pratiquement impliquée dans tous les domaines de la science et technologie des matériaux. L’utilisation des sels de diazonium est justifiée par le fait qu’ils adhèrent aux surfaces avec de fortes énergies de liaison, en particulier sur le carbone sp², ce qui en fait d’excellents agents de couplage pour les polymères aux surfaces. Dans ce contexte, nous avons travaillé sur deux types de nanohybrides de nanotubes de carbone (NTC) : NTC-polytriazole (NTC-PTAz) et NTC-colorant. Le nanohybride NTC-PTAz a été synthétisé par polymérisation « click » en surface. Pour ce faire, les NTCs ont été greffés de groupes 4-azidophényle à partir du sel de diazonium correspondant. Le NTC modifié (NTC-N3) a servi de support pour une polymérisation confinée en surface de type polyaddition générant ainsi le nanohybride NTC-PTAz. Ce matériau a été caractérisé par ATG, XPS, IR et Raman. Ses applications potentielles sont dans le développent d’adsorbants de métaux lourds, l’immobilisation de nanocatalyseurs ou pour le stockage des gaz. La seconde partie de la thèse est plus étoffée et porte sur les nanotubes de carbone greffés de colorants diazotés Rouge Neutre (NR), Azure A (AA) et Rouge Congo (CR). L’analyse fine de ces matériaux a révélé une très forte adhésion des colorants aux NTCs et les couches superficielles ont des épaisseurs de 2 à 6 nm, sont homogènes et continues. Les NTC-colorant ont été incorporés dans des matrices élastomères de type EVA pour la réalisation d’actionneurs opto-thermiques implantés dans des pads pour non-voyant. Dans les matrices EVA, les NTCs greffés de colorants servent à capter la lumière et induire un changement de forme dans le pad qui soit palpable par le non voyant (250 µm). Les matrices EVA renforcées de nos nanotubes greffés de colorants ont été réalisées et testées par analyse mécanique dynamique. Les composites NTC/colorant-EVA sont flexibles et prometteurs pour le développement de nouveaux types des pads tactiles pour les non-voyants. Les nanohybrides NTC-NR ont servi comme capteurs chémo-résistifs pour la reconnaissance moléculaire de l’acétone.Dans une dernière application, le nanohybride CNT-CR a été étudié en tant qu’électrocatalyseur pour l’oxydation directe du méthanol. Des résultats intéressants ont été obtenus avec ces nanohybrides mais des améliorations significatives (rapport 3) des propriétés électrocatalytiques ont été obtenues avec des CNT-CR décorés avec des nanoparticules d'or. Le système électrocatalytique nouvellement conçu pourrait être considéré pour différentes applications prometteuses, notamment les capteurs, les biocapteurs, les catalyseurs hétérogènes pour les piles à combustible. Pour résumer, les nanohybrides à base de CNT nouvellement conçus présentent des performances uniques attribuées à la polyvalence de la chimie d'interface du diazonium pour la fixation efficace de couches moléculaires et macromoléculaires fonctionnelles. Les nanohybrides novateurs servent de blocs de construction pour la conception de matériaux nanocomposites à hautes performances potentiellement utiles dans les nouveaux défis socio-économiques tels que l’environnement, la biomédecine et l’énergieDiazonium interface chemistry has progressed over the last few years and practically involved in all areas of materials science and engineering. The rationale for employing diazonium salts is that they attach to surfaces with remarkable bond energies, particularly on sp² carbon materials, making them an ideal coupling agent for polymers to surfaces In this context, novel CNT-polytriazole (CNT-PTAz) and CNT-dye nanohybrids were designed and thoroughly characterized. First, CNT-PTAz nanohybrid was prepared by click polymerization: multiwalled carbon nanotubes (CNTs) were modified with azidophenyl groups (CNT-N3) from 4-azidobenzenediazonium precursor and served as nanoscale platform for the surface confined polyaddition. The CNT-PTAz nanohybrid was characterized by TGA, XPS, IR, and Raman. The robust CNT-PTAz is robust and has potential in developing heavy metal adsorbents, nanosupport for catalysts or for gas storage. In the second major part, we grafted CNT with diazotized Neutral red (NR), Azure A (AA) and Congo Red (CR) dyes by simple, spontaneous reaction of the diazonium salts and CNTs in water, at RT. A thorough investigation of the nanohybrids showed that the adhesion is strong (CNT-dye C-C bond energy higher than 150 kJ/mol), and the layer is uniform. These nanohybrids further served to reinforce ethylene-vinyl acetate (EVA) an elastomeric matrix. The reinforced matrix is flexible and serves as optothermal actuators where the grafted dye catches the light to induce mechanical changes in the matrix monitored by dynamic mechanical analysis. CNT/dye-reinforced EVA is a promising flexible composite for developing new types of visual-aid tablet for visually impaired people. The versatile CNT-dye nanohybrids are also unique chemiresistive gas sensors for the molecular recognition of acetone vapours. In a final application, CNT-CR nanohybrid was investigated as an electrocatalyst for the Direct Oxidation of Methanol. Interesting results were obtained with these nanohybrids but significant improvements (3-fold) of the electrocatalytic properties were achieved with CNT-CR decorated with gold nanoparticles. The newly designed electrocatalytic system could be regarded for different promising applications most likely as for sensors, biosensors, heterogeneous catalysts for fuel cells and for nanotechnology To summarize, newly designed CNT-based nanohybrids have unique performances ascribed to the versatility of the diazonium interface chemistry in efficiently attaching functional molecular and macromolecular layers. The novel nanohybrids serve as building blocks for designing high performance nanocomposite materials relevant to challenging timely social economic issues, namely environment, biomedicine and energy
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Mokrani, Touhami. "The development of inorganic and organic/inorganic membranes for DMFC application". Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&.
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A fuel cell is an energy device that converts chemical energy to electrical energy. Low temperature fuel cells, namely the hydrogen fuel cell and the direct methanol fuel cell are preferred amongst other fuel cell types for stationary and vehicular applications, due to their small size and their low operating temperature. The direct methanol fuel cell has several advantages over the hydrogen fuel cell including ease of transport and storage since methanol is a liquid. Since methanol is used directly in the cell there is no need for a reforming process, which results in a less complicated system. However, direct methanol fuel cell are in their infancy and many problems need to be overcome before reaching commercialization. The direct methanol fuel cell has several disadvantages, namely, the sluggish methanol oxidation reaction, the high cost of state-of-the-art proton exchange membranes, the high methanol permeability from anode to cathode and the dependence on the conductivity on membrane water content, which limits their use to temperatures below the boiling point of water, while the need is to work at high temperatures. Attempts to overcome the disadvantages of the state-of-the-art membrane were made in this study, including the development on novel proton exchange membranes and also the modification of existing state-of-the-art membranes.
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Dennis, Shelli R. "Nucleation and growth of inorganic crystals at the organic-inorganic interface /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8050.
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Keum, Dong-ki. "Organic-inorganic composites of CaCO3 particles by organic polymer templates". 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147661.
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Edwards, Robert. "The chemistry of tin and lead archaeological artefacts". Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366456.
Texto completoResumen
The present work explores the long term corrosion phenomena of lead and tin in saline and other conditions. Thermodynamic results are presented for the minerals abhurite, blixite, mendipite, paralaurionite, stannite and the compounds Pb706Cl2.2H20 and Sn30(OH)2S04 at 298.2K and P = 105 Pa. At this temperature laurionite is stable, rather than its dimorph, paralaurionite, and mendipite is in fact metastable, being thermodynamically stable above 29 0 C. Kinetic influences are significant with respect to the sequence of formation of solid phases in the PbO - H20 - HCl system, and these have been elucidated for some important reactions. Penfieldite and fiedlerite appear to be metastable at all temperatures at 105 Pa. These results have been used to develop a model for the formation of lead(II) oxy- and hydroxy- chloride phases that are known as minerals and as corrosion products of lead-containing artefacts. The effect of C02 on the system is also discussed. A new synthesis of sn30(OH)2S04 is described, and its stability constant in aqueous solution has been determined by direct ~easurement of the activities of Sn2+ and s04 2- using ion selective electrodes. The true formula·of abhurite is Sn2l06(OH)14Cl16' which corresponds to a synthetic phase of known crystal structure. The results have been used to assess the relative stabilities of these compounds in the natural environment and their modes of occurrence in relation to other secondary Sn(II) and Sn(IV) species. Finally, some divalent metal hexahydroxystannates have been made, and their role in the corrosion of tin and its alloys assessed. The electrochemical oxidation of stannite has been studied and some correlation has been made between the supergene minerals formed and solution chemistry.