Research in fluorescent solar concentrators (FSCs) commenced in mid-1970’s to lower the cost of solar cells through the reduction of the required solar cell active area, and by incorporating them in-to buildings, thereby offsetting installation costs. In FSCs, light penetrates the top surface of a waveguide, is absorbed by the fluorescent material (FM) and is emitted at a longer wavelength that is then internally reflected towards edge solar cells. In this project, the use of cerium doped yttrium aluminum garnet (Ce:YAG) was explored as an FM, from which the optical transport of fluorescence must be enhanced towards solar cell edges. Optical spectroscopic techniques were conducted to characterize a sample of Ce:YAG with a doping level of 0.180 mol%. An excitation and emission profile indicated a strong absorption at 476 nm and a strong radiation at 530 nm, where the fluorescence process lasted for only 62.3 ns, with a conversion efficiency of 80.0%. Meanwhile, x-ray analysis concluded that this material had a density of 4.56 g/cm3. An acrylic concentrator with local islands of Ce:YAG was successfully fabricated. A lens sheet was used to provide strong sunlight coupling to Ce:YAG. The concentrator was analysed using Optics Lab, Monte Carlo simulations (MCS) and through experimental flux measurements, the percentage of light that waveguided to the edges was determined. Optics Lab yielded 56.10%, MCS yielded 59.20% and flux measurements resulted in 58.22% (without lenses) and 57.14% with lenses. Also, an overall experimental optical efficiency was determined to be 32.45% without lenses and 53.53% with lenses. These results can be improved by modifying the fabrication techniques and using substrates with higher refractive indices. / Thesis / Master of Applied Science (MASc)

This research serves as a meticulous examination into cross-conjugated materials and how alterations of the frontier molecular orbitals can be utilized for applications in "chemical tongue" organic sensing devices. With conjugated materials being used in the development of new sensory devices for detection of metals, bacteria, and chemical warfare agents, the field of organic sensing is growing faster than ever. The purpose of this dissertation is to provide a precedence for the synthesis of new cross-conjugated compounds and outline potential applications of these materials as chemical sensors and molecular probes.

Le travail présenté dans cette thèse est une contribution pour progresser vers des mesures thermiques plus quantitatives. Il s'agit de mesurer la température par la technique RIF de l'émission verte. Les travaux réalisés dans ce mémoire s'articulent en trois étapes. Au départ nous avons mesuré la température d'échauffement d'un cristal massif Sr0.3Cd0.7F2 codopés Er3+/Yb3+ d'épaisseur 0.3 mm. L'échauffement induit par l'excitation des ions Yb3+ à 974.4 nm a été mesurée à une distance (d) au bord de cristal, par l'émission verte des ions Er3+ excité par le laser rouge (652 nm) au bord du cristal. La seconde étape a eu pour but la mesure de la température d'échauffement du même cristal précédent, mais en dimension microscopique. Ces microparticules fluorescentes ont été fixées à l'extrémité d'une sonde thermique de Wollaston. L'échauffement des microparticules se fait par une excitation laser rouge à 652 nm ou par effet Joule en parcourant un courant électrique dans la sonde thermorésistive. La troisième étape a eu pour principal objectif la mesure de la température à l'échelle micrométrique en utilisant un microscope à force atomique (AFM) sur lequel est montée une sonde thermorésistive munie à son extrémité d'une microparticule fluorescente de Sr0.3Cd0.7F2 codopée Er3+/Yb3+ de 15 µm utilisée comme capteur de température. La technique est basée sur la variation de l'intensité de la fluorescence de la microparticule en contact avec une surface chaude. Cette nouvelle technique nous a permis d'obtenir une image cartographique de la température d'un microsystème, composé de lignes chauffantes submicroniques, chauffé par effet Joule. / The work presented in this thesis is a contribution to progress towards more quantitative thermal measurements. This is to measure the temperature by RIF technique green emission. The work in this thesis is divided into three stages. Initially we measured the temperature rise of a massive crystal Sr0.3Cd0.7F2 codoped Er3 + / Yb3 + 0.3 mm thick. The heat induced by the excitation of Yb3 + ions to 974.4 nm was measured at a distance (d) at the edge of crystal, the green emission of the Er3 + ions excited by red laser (652 nm) at the edge of the crystal.The second step was designed to measure the temperature of the heating of the same previous crystal, but in microscopic dimensions. These fluorescent microparticles were attached to the end of a thermal probe Wollaston. The temperature rise of the microparticles is by a red laser excitation at 652 nm or by Joule effect through an electric current in the probe thermorésistive.The third step was the main aim of measuring the temperature using a micrometric scale atomic force microscope (AFM) on which is mounted at its end provided with one of a fluorescent microparticle thermorésistive probe Sr0.3Cd0.7F2 codoped Er 3 + / Yb 3 + 15 microns used as a temperature sensor. The technique is based on the change in fluorescence intensity of the microparticle in contact with a hot surface. This new technique allowed us to obtain a map image of the temperature of a microsystem consisting of submicron heating lines, heated by Joule effect.

The organic light-emitting diode (OLED) technology is emerging to be the future technology of choice for thin, flexible and efficient display and lighting panels and is a potential competitor for the existing flat panel display technologies, like liquid crystal display (LCD) and plasma display panel (PDP). OLEDs display is already making their way from both lab and industry research to display market and the pace of development of laboratory OLED design into a commercial product is very impressive. The OLED display offers several advantages over other display technologies, such as low power consumption, easy fabrication, high brightness & resolution, light weight, compact, flexible, wide viewing angle and fast response. However, OLED display is still in amateur stage in terms of their cost and lifetime. Despite of the abovementioned advantages of OLEDs, there still several issues that need to be addressed to explore the full potential of this display technology. The development of materials with high photoluminescence quantum yield (PLQY), thermal and electrochemical stability, packaging, and light extracting technology are some of the major issues. Among the emitting materials, the achievement of robust blue emitting material with high PLQY and color purity is still a challenge due to its intrinsic wide bandgap and complex device configuration. The work presented in this thesis is devoted to the development of robust blue emitting materials based on fluoranthene derivatives. Fluoranthene unit has been chosen due to its blue emission, high photoluminescence quantum yield, thermal and electrochemical stability. The thesis is organized in six chapters, and a brief discussion on the content of individual chapters is provided below. Chapter 1 provides a short description of evolution of display technology and history of OLEDs. The generation wise development of emitting materials for white OLED is concisely illustrated. The working principle, function of individual layer and factors governing external quantum efficiency of OLED device are elaborated. Finally, the important prerequisite properties of blue emitting materials for OLED application are outlined. Chapter 2 reports the design and synthesis of symmetrically and asymmetrically functionalized fluoranthene-based materials to address the issue of PL quenching in solid state, and subsequently for application in non-doped electoluminescent devices. A detailed experimental and theoretical study has been performed to understand the effect of symmetric and asymmetric functional groups on optical, thermal and electrochemical properties. The fluoranthene derivatives reported in this chapter exibited deep blue emission with high PLQY in both solution and solid state. The vacuum deposited non- doped OLED devices were fabricated and characterized utilizing these materials as emitting layer. Chapter 3 describes the rationale design of thermally stable fluoranthene derivatives as electron transport materials for OLEDs. The two derivatives investigated in this chapter comprised of two fluoranthene units linked by diphenylsulfane and dibenzothiophene linkage. The effect of rigidity provided by ring closure in molecular structure on the physical and charge transport properties has been investigated. Such materials are urgently demanded for better performance and durability of displays. In an extension to chapter 3, fluoranthene based dual functional materials possessing blue light emission and electron transport characteristics are described in Chapter 4. The application of these materials in bilayer blue OLED device successfully demonstrated. The development of such dual functional materials is an important step to not just simplify the OLED device architecture; but also has the potential to reduce the manufacturing and processing cost significantly. Chapter 5 reports the synthesis of the star-shaped fluoranthene-triazine based blue photoluminescent materials for solution processable OLEDs. The effect of chalcogen on the photophysical and electroluminescence properties has been investigated. The main advantage of such solution processable materials over small molecules is to overcome the power consuming vacuum thermal evaporation technique for deposition. Chapter 6 describes the design and synthesis of a new blue emitting material comprising of a donor moiety and an acceptor unit to observe thermally activated delayed fluorescence (TADF). However, photophysical studies did not show any sign of delayed fluorescence in this molecule. Nevertheless, a deep blue electroluminescence is achieved using a multilayer OLED device configuration.

La presente tesis doctoral titulada ¿Materiales funcionales híbridos para el reconocimiento óptico de explosivos nitroaromáticos mediante interacciones supramoleculares¿ se basa en la combinación de principios de Química Supramolecular y de Ciencia de los Materiales para el diseño y desarrollo de nuevos materiales híbridos orgánico-inorgánicos funcionales capaces de detectar explosivos nitroaromáticos en disolución. En primer lugar se realizó una búsqueda bibliográfica exhaustiva de todos los sensores ópticos (cromogénicos y fluorogénicos) descritos en la bibliografía y que abarca el periodo desde 1947 hasta 2011. Los resultados de la búsqueda están reflejados en el capítulo 2 de esta tesis. El primer material híbrido preparado está basado en la aplicación de la aproximación de los canales iónicos y, para ello, emplea nanopartículas de sílice funcionalizadas con unidades reactivas y unidades coordinantes (ver capítulo 3). Este soporte inorgánico se funcionaliza con tioles (unidad reactiva) y una poliamina lineal (unidad coordinante) y se estudia el transporte de una escuaridina (colorante) a la superficie de la nanopartícula en presencia de diferentes explosivos. En ausencia de explosivos, la escuaridina (color azul y fluorescencia intensa) es capaz de reaccionar con los tioles anclados en la superficie decolorando la disolución. En presencia de explosivos nitroaromáticos se produce una inhibición de la reacción escuaridinatiol y la suspensión permanece azul. Esta inhibición es debida a la formación de complejos de transferencia de carga entre las poliaminas y los explosivos nitroaromáticos. En la segunda parte de esta tesis doctoral se han preparado materiales híbridos con cavidades biomiméticas basados en el empleo de MCM-41 como soporte inorgánico mesoporoso (ver capítulo 4). Para ello se ha procedido al anclaje de tres fluoróforos (pireno, dansilo y fluoresceína) en el interior de los poros del soporte inorgánico y, posteriormente, se ha hidrofobado el interior de material mediante la reacción de los silanoles superficiales con 1,1,1,3,3,3-hexametildisilazano. Mediante este procedimiento se consiguen cavidades hidrófobas que tienen en su interior los fluoróforos. Estos materiales son fluorescentes cuando se suspenden en acetonitrilo mientras que cuando se añaden explosivos nitroaromáticos a estas suspensiones se observa una desactivación de la emisión muy marcada. Esta desactivación de la emisión es debida a la inclusión de los explosivos nitroaromáticos en la cavidad biomimética y a la interacción de estas moléculas (mediante interacciones de ¿- stacking) con el fluoróforo. Una característica importante de estos materiales híbridos sensores es que pueden ser reutilizados después de la extracción del explosivo de las cavidades hidrofóbicas. En la última parte de esta tesis doctoral se han desarrollado materiales híbridos orgánicoinorgánicos funcionalizados con ¿puertas moleculares¿ que han sido empleados también para detectar explosivos nitroaromáticos (ver capítulo 5). Para la preparación de estos materiales también se ha empleado MCM-41 como soporte inorgánico. En primer lugar, los poros del soporte inorgánico se cargan con un colorante/fluoróforo seleccionado. En una segunda etapa, la superficie externa del material cargado se ha funcionalizado con ciertas moléculas con carácter electrón dador (pireno y ciertos derivados del tetratiafulvaleno). Estas moléculas ricas en electrones forman una monocapa muy densa (debida a las interacciones dipolo-dipolo entre estas especies) alrededor de los poros que inhibe la liberación del colorante. En presencia de explosivos nitroaromáticos se produce la ruptura de la monocapa, debido a interacciones de ¿-stacking con las moléculas ricas en electrones, con la consecuencia de una liberación del colorante atrapado en el interior de los poros observándose una respuesta cromo-fluorogénica / Salinas Soler, Y. (2013). Functional hybrid materials for the optical recognition of nitroaromatic explosives involving supramolecular interactions [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31663 / TESIS / Premios Extraordinarios de tesis doctorales