In dieser Arbeit werden Strategien zur Entwicklung von biohybriden Photoelektroden, die Licht in elektrische Energie umwandeln, demonstriert und diskutiert. Der natürliche Photonen-transformierende Superkomplex der oxygenen Photosynthese aus Thermosynechococcus elongatus, das Photosystem I (PSI), kann durch die nicht-native Interaktion zum Redoxprotein Cytochrom c (Cyt c), erfolgreich funktional in Elektroden integriert werden. Hierfür wurden unterschiedliche Strategien entwickelt, z. B. bilden beide Biokomponenten unspezifische Komplexe in Lösung und assemblieren gemeinsam auf modifizierten Goldoberflächen. Aus der Kontaktierung des PSI mit einer thiol-modifizierten Goldelektrode via Cyt c ergeben sich unidirektionale kathodische Photoströme. DNA, als ein Polyelektrolytmatrixelement, kann zum Aufbau von 3D-Protein-Mehrschichtarchitekturen höherer Stabilität und Leistungsfähigkeit verwendet werden. Der Einsatz von mesoporösen Indium-Zinnoxid-Elektroden vergrößert die Photostromgenerierung um mehr als eine Größenordnung, wodurch sich hieraus skalierbare transparente Photobioelektroden mit hohen Quanteneffizienzen (bis zu 30%) erzeugen lassen. / In this thesis, strategies are demonstrated and discussed for the development of biohybrid photoelectrodes transforming light into electrical energy. The natural photon-to-charge carrier converting super-complex from oxygenic photosynthesis of Thermosynechococcus elongatus, photosystem I (PSI), can be functionally implemented into such electrodes, due to the non-native interaction with the small redox protein cytochrome c (cyt c). Different strategies have been developed, e. g. both biocomponents form complexes in solution and self-assemble on modified gold-surfaces. The electrical connection of PSI to thiol-modified gold electrodes via cyt c results in unidirectional cathodic photocurrents of high efficiency. DNA, as a polyelectrolyte matrix element, can be used to build up 3D protein multilayer architectures of higher stability and performance. The use of mesoporous indium tin oxide electrodes further enhances the photocurrent generation more than one order of magnitude, thus resulting in scalable transparent photobioelectrodes of high quantum efficiencies (up to 30 %).

Ausgangspunkt dieser Arbeit war die Frage, inwieweit die zur Herstellung von Compositmaterialien aus leitfähigen Polymerfilmen (Polythiophen, Polypyrrol) und Metalloxidschichten (anodisch oxidiertes Titan, chemisch oxidiertes Silicium bzw. Aluminium) entwickelte Präparationsmethode auf die Herstellung hybrider Core - Shell - Partikel (Core: Metalloxidpartikel; Shell: leitfähiges Polymer) übertragbar ist. Die erfolgreiche Beschichtung dispergierter Oxidpartikel mit leitfähigen Poly- meren zeigte, dass nicht nur eine analoge Verfahrensweise (Adsorption des Monomers auf der Substratoberfläche und anschließende Zugabe des Oxidationsmittels) verwendet werden konnte, sondern dass bei der Pulverbeschichtung infolge der großen spezifischen Oberfläche der Materialien auch ohne Einsatz spezieller Haftvermittler, hervorragende Schichtqualitäten (hohe Haftfestigkeit, hoher Be- deckungsgrad) erreicht wurden, und die auf diesem Wege hergestellten Verbundmaterialien in Pulverform in beliebiger Menge, Partikelgröße und Zusam-mensetzung verfügbar waren. Der durch die Verkapselung der Oxidteilchen mit intrinsich leitfähigen Polymeren bewirkte enge Kontakt zwischen Polymer- und Oxidphase und die auf diesem Wege realisierte Oberflächenmodifizierung führte zu einem im Vergleich zu den reinen Komponenten wesentlich veränderten Eigenschaftsspektrum. Durch die Herstellung von Compositen waren die leitfähigen Polymere leichter dispergierbar, und konnten kathaphoretisch in guter Qualität, auch auf großen Substratflächen abgeschieden werden. / Starting with the question about the possibility of producing composites based on conducting polymer films (polythiophene, polypyrrole) and metal oxide layers (anodically oxidized titanium, chemical oxidized silicon or aluminium) it was the goal of this work to transfer and modify this method for the preparation of hybrid core - shell - particles (core: metal oxide particle; shell: conducting polymer). By the successfully covering of dispersed oxide particles it was shown, that not only an analogous procedure (adsorption of the monomer on the substrate surface and the following addition of an oxidant) can be used, but that in the case of powder covering because of the high specific surface area of the oxide powders, outstanding layer qualities without using adhesion promotors can be produced. Following this way, powder-like compound materials can be ordered and designed in any quantity, particle size and composition. Through the encapsulation of the oxide particles with intrinsic conducting polymers a narrow contact between the polymer and the oxide phase and a surface modification were made by a very simple way. By this surface modification a totally different behaviour of the composites, compared to their components was realized. The producing of composites allowes a better dispersibility of conducting polymers and their cathaphoretically deposition with a good quality, also on larger substrate surfaces.

Conducting polymer nanocomposites composed of metal oxides and polythiophene was synthesized by chemical polymerization in colloidal suspensions. The electrochemical and photoelectrochemical properties of such nanocomposites have been studied. For these investigations films of nanocomposites were prepared by an electrophoretic deposition process. The deposition process was studied in greater detail and kinetic details were determined. The high voltage electrophoretic deposition process was combined with a quartz crystal microbalance (QCM). Then the films were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and photocurrent spectroscopy.

Esta tese teve por objetivo, desde seu início, investigar as propriedades elétricas de um dispositivo ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al, o qual é uma estrutura bem conhecida de célula solar orgânica do tipo de heterojunção de volume (bulk-heterojunction – BHJ), e com isso dar uma contribuição à melhora de seu desempenho. Porém, o primeiro passo foi introduzir no Grupo de Polímeros Bernhard Gross, um método eficaz de produzir células solares do tipo BHJ com boa eficiência e reprodutibilidade. Esse primeiro desafio foi alcançado com sucesso. A eficiência (η) de um dispositivo fotovoltaico de multicamadas depende de muitos fatores. Dentre eles, uma boa superposição entre o espectro solar e a curva de absorção da camada absorvedora, uma excelente conversão da energia luminosa em portadores de carga, um eficiente processo de condução e uma perda mínima por recombinação e armadilhamento de portadores. Além disso, a compatibilidade eletrônica entre as interfaces tem um papel fundamental na definição na tensão de circuito aberto (VOC), no valor da corrente de curto-circuito (JSC), e no fator de preenchimento (FF). Baseado nesses efeitos, realizamos uma série de medidas experimentais, que auxiliado por um modelo teórico proporcionaram um estudo detalhado da evolução em função da temperatura da mobilidade dos portadores (μ) e de seu tempo de vida (τ). Os principais experimentos nessa tese foram realizados em diferentes temperaturas (entre 100 e 340 K). Foram eles: medidas de fotocorrente - Jph(V), a técnica de foto-CELIV, e medidas de transiente de fotovoltagem (TPV). Em paralelo, desenvolvemos o modelo teórico para a descrição analítica de Jph(V) que assumiu contatos não-injetores e que o livre caminho médio (w = μτF) de elétrons e buracos eram iguais (F é o campo elétrico). Nos ajustes teórico/experimental usamos a probabilidade de dissociação dos estados de transferência de carga (P) e o produto μτ como parâmetros de ajuste. A condição na qual o livre caminho médio é maior que a espessura da amostra (w >> L) reproduz a corrente de saturação reversa, Jsat = qGPLG é a taxa de geração dos éxcitons. Para w << L, a fotocorrente varia linearmente com o livre caminho médio, ou seja, J(F) = qGPμτF. A comparação entre os resultados experimentais e os teóricos permitiram, além da obtenção da evolução das grandezas μ e τ com a temperatura, estabelecer uma relação efetiva entre os parâmetros da célula (η, JSC, e FF) e as propriedades elétricas da camada ativa P3HT:PCBM. As medidas termo-mecânicas (DMA) forneceram informações adicionais sobre mudanças estruturais da camada ativa, as quais foram correlacionadas com variações dos parâmetros da célula e com fatores de perda. Finalmente, medidas de tempo-de-voo (TOF) e de CELIV foram realizadas para estudos mais detalhados sobre mecanismos de transporte ao longo da camada ativa, a efeitos de injeção pelos eletrodos, e para o entendimento de efeitos de degradação pela ação do oxigênio. / This thesis aims to investigate electrical characteristics of an ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al device, which is a well-known structure of a bulk-heterojunction (BHJ) organic solar cell, and to contribute to improve its performance. However, the first step was to introduce in the Group of Polymer Bernhard Gross an effective method for producing BHJ solar cells, manufacturing thus devices exhibiting excellent performance and reproducibility. This thesis aims to investigate electrical characteristics of an ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al device, which is a well-known structure of a bulk-heterojunction (BHJ) organic solar cell, and to contribute to improve its performance. However, the first step was to introduce in the Group of Polymer Bernhard Gross an effective method for producing BHJ solar cells, manufacturing thus devices exhibiting excellent performance and reproducibility. This goal was successfully achieved. The good efficiency (η) of a multilayer photovoltaic cell depends on many factors, including good overlap between the solar spectrum and the light absorbing layer, an excellent conversion of the absorbed light energy in pairs of electronic carriers, efficient charge transport and the minimum losses by recombination or by the action of deep traps for the carriers. Furthermore, the compatibility between electronic interfaces plays a crucial role in defining the open-circuit voltage (VOC) and the value of short-circuit current (JSC), and on the fill factor (FF). Anchored on these effects, we carried out a series of experiments, aided by a theoretical modeling, which provided a detailed study of the temperature evolution of fundamental electric quantities such as carrier mobility (μ) and its lifetime (τ). These studies were performed with the help of different experiments: photocurrent in function of the applied voltage  Jph(V), Photo-CELIV technique, and Transient Photovoltage (TPV) measurements, which were carried out at several temperatures in the 100 to 340 K range. In parallel, we developed an analytical model for Jph(V) that assumed non-injecting contacts and equal mean-free-paths for electrons and holes. The theoretical/experimental entities used as fitting parameters were the charge-transfer-state dissociation probability (P) and the μτ product. The condition in which the mean-free-path (w = μτF) is higher the sample thickness (L), the model reproduces the experimental reverse saturation current, Jsat = qGPL, which is coincident with the experimental value. F is the internal electric field and G is the generation rate of excitons by the absorbed light. When w << L, J(F) = qGPμτF, which is also coincident with experimental behavior. The confrontation between the experimental results and the theoretical model provided, in addition to the study of the evolution of μ and τ with temperature, to establish a more effective relationship between the parameters (η, JSC, e FF) of the cell and the electrical properties of the P3HT:PCBM active layer. Thermomechanical analysis (DMA) provided additional information of structural changes of active layer, which can be correlated with change in the loss factor and in the cell parameters. Finally, Time-of-Flight (TOF) and CELIV techniques were used in the more accurate study of charge transport along the active layers, effects of injection by the electrodes, and the degradation effect caused by oxygen.

Différents systèmes polyoxométallates@M-colorants ont été réalisés dans cette thèse pour électrochimique dégagement d'hydrogène catalytique et génération photocourant.• Des films hybrides, basés sur des interactions électrostatiques entre une porphyrine tetracationique et des nanoparticules stabilisées par des POMs du type POM@Pt sur ITO, ont été formés par la méthode dite couche par couche et ont été utilisés pour la génération de H2 ou de photocourant. • Pour améliorer le transfert de charge entre les nanoparticules POM@M et le substrat, la réduction de l'oxyde de graphène a été réalisée pour former des systèmes hybrides rGO/POM@Pt. Le dégagement d'hydrogène a été mesuré.• Les copolymères polycationiques bis-porphyrine ont également été obtenus par électropolymérisation avec des espaceurs bis-pyridinium. Par réaction de métathèse, l’incorporation avec divers POM de type Keggin ou des nanoparticules du type POM@Ag ont ensuite été realise. Leurs performances photovoltaïques ont ensuite été étudiées.• Enfin des films hybrides PEDOT dopés avec des nanoparticules du type POM@M ont également été fabriqués. Les performances photovoltaïques ont été examinés montrant une forte amélioration sous illumination dans le domaine du visible. L’ensemble de ces matériaux hybrides ont montré des propriétés intéressantes pour des applications photovoltaïques et la conversion d'énergie. / Polyoxometalates@M NPs-dyes molecular hybrid systems were realized in this thesis for electrochemical catalytic hydrogen evolution and photocurrent generation. • First, hybrid films, based on electrostatic interactions between the tetracationic porphyrin and POMs@Pt NPs composites on ITO slides, were formed by the so called Layer-by-Layer method for HER and photocurrent generation.• To improve the charge transfer between POMs@M NPs and the substrate, reduced graphene oxide was introduced to form rGO/POMs@Pt NPs hybrid systems. Hydrogen evolution was measured after dropping this composites onto the surface of glassy carbon electrodes.• Polycationic bis-porphyrin copolymers have been also obtained by an electropolymerization leading to the formation of new bis-porphyrin copolymers with pyridinium as spacers. Incorporation with various Keggin type POMs or POMs@Ag was then achieved, their photovoltaic performances were also studied.• POMs@M NPs doped PEDOT hybrids films have been also fabricated. The photovoltaic performances has been examined showing particularly strong enhancement under visible light. In conclusion, these polyoxometalates based hybrids materials have shown interesting properties for photovoltaic application and energy conversion.

This work concerns with today's challenges of photoelectrical characterization methods in the research and development of thin film silicon solar cells. Relevant results are obtained only when photocurrent spectroscopy and measurement of current-voltage characteristics, are applied on the real structures that can however be multi-layered, multi-junction devices with nanostructured interfaces. Analytical and numerical optical models comprising light scattering are used for analysis of light absorption and for evaluation of optical absorption coefficient of silicon layers in sub-gap region. The slope of absorption edge and residual absorption in mid-gap indicate material disorder and defect density. Based on the investigation of electrical interaction between sub-cells in the dual-junction solar cell we developed new methods of evaluation of photocurrent spectra and current-voltage characteristics individually for each sub-cell with no need to contact them directly. Usability of Fourier Transform Photocurrent Spectroscopy as a robust method for photocurrent spectroscopy of amorphous silicon is thoroughly analyzed here. The issues of frequency dependence are addressed in detail and comparison with photothermal deflection spectroscopy is made.

No description available.

[ES] Uno de los retos más importantes de la sociedad actual es la obtención de energía de forma sostenible, limpia y eficiente. Por ello, gran parte de la investigación actual en el campo de la química y la ciencia de los materiales centra sus esfuerzos en la búsqueda y estudio de nuevas generaciones de materiales que permitan una transición energética desde el modelo energético tradicional hacia un modelo más sostenible. En este contexto, las propiedades eléctricas de los materiales, relacionadas con la generación y transformación de energía, juegan un papel esencial. En esta tesis se estudian dos tipos de materiales híbridos con distinta estructura y composición, pero que combinan excelentes propiedades eléctricas y ópticas. Por una parte, los clústeres octaédricos de molibdeno, ya conocidos desde hace décadas, han demostrado ser excelentes materiales en catálisis. En los últimos tiempos, la investigación alrededor de este material se ha centrado en el estudio de sus propiedades ópticas y electrónicas y sus aplicaciones en sensores y dispositivos emisores de luz. Por otra parte, las perovskitas híbridas halogenadas son ampliamente conocidas en el campo de la generación energética por sus elevadas eficiencias, movilidad de cargas y alta eficiencia de emisión de luz. Se han estudiado dos estructuras de perovskita híbrida halogenada: una 3D, cuyas propiedades son ampliamente conocidas, y otra con estructura multidimensional 2D-3D, donde el carácter laminar le confiere una mejora en la estabilidad. Con el propósito de comprender mejor su interacción luz-materia, en los trabajos desarrollados en la presente tesis, se han realizado mediciones optoelectrónicas a nivel monocristalino. Esto incluye un análisis combinando de medidas de emisión, fotocolección y transporte de carga. Además, se ha investigado su comportamiento como cavidad resonante, así como sus propiedades como generador de energía. Por lo tanto, se ha corroborado que los materiales objeto de estudio, presentan unas propiedades que les confieren diferentes posibilidades de aplicación en diversos ámbitos dentro del campo de la generación energética. / [CA] Un dels reptes més importants de la societat actual és obtenir energia de forma sostenible, neta i eficient. Per això, gran part de la investigació actual en el camp de la química i la ciència dels materials centra els seus esforços en la cerca i l'estudi de noves generacions de materials que permeten una transició energètica des del model energètic tradicional cap a un model més sostenible. En aquest context, les propietats elèctriques dels materials, relacionades amb la generació i la transformació d'energia juguen un paper essencial. En aquesta tesi s'estudien dos tipus de materials híbrids amb diferent estructura i composició, però que combinen propietats elèctriques i òptiques excel·lents. D'una banda, els clústers octaèdrics de molibdè, ja coneguts des de fa dècades, han demostrat ser materials idonis en catàlisi. De fet, en els darrers temps, la recerca al voltant d'aquest material s'ha centrat en l'estudi de les propietats òptiques i electròniques i les aplicacions en sensors i dispositius emissors de llum. D'altra banda, les perovskites híbrides halogenades són àmpliament conegudes al camp de la generació energètica per les seues elevades eficiències, mobilitat de càrregues i alta eficiència d'emissió de llum. S'han estudiat dues estructures de perovskita híbrida halogenada: una de 3D, les propietats de la qual són àmpliament conegudes, i una altra amb estructura multidimensional 2D-3D, el caràcter laminar de la qual li confereix una millora en l'estabilitat. Amb el propòsit de comprendre millor la seua interacció llum-matèria, en els treballs desenvolupats en aquesta tesi, s'han realitzat mesuraments optoelectrònics a nivell monocristal·lí. Això inclou una anàlisi que combina mesures d'emissió, fotocol·lecció i transport de càrrega. A més, s'ha investigat el seu comportament com a cavitat ressonant, així com les seues propietats com a generador d'energia. Per tant, s'ha corroborat que els materials objecte d'estudi presenten unes propietats que els confereixen diferents possibilitats d'aplicació en diversos àmbits dins del camp de la generació energètica. / [EN] One of the most important challenges of today's society is obtaining energy in a sustainable, clean, and efficient way. For this reason, much of the current research in the field of chemistry and materials science focuses its efforts on the search and study of new generations of materials that allow an energy transition from the traditional energy model to a more sustainable model. In this context, the electrical properties of materials, related to the generation and transformation of energy, play an essential role. In this thesis, two types of hybrid materials with different structure and composition, but which combine excellent electrical and optical properties, are studied. On the one hand, octahedral molybdenum clusters have been known for decades and have proven to be excellent materials in catalysis. In fact, in recent times, research around this material has focused on the study of its optical and electronic properties and its applications in sensors and light-emitting devices. On the other hand, halogenated hybrid perovskites are widely known in the field of energy generation for their high efficiencies, charge mobility and high light emission efficiency. Two halogenated hybrid perovskite structures were studied: one 3D, whose properties are widely known, and another with a 2D-3D multidimensional structure, where the laminar character confers an improvement in stability. To better understand its light-matter interaction, in the work developed in this thesis, optoelectronic measurements have been carried out at the monocrystalline level. This includes a combined analysis of emission, photocollection and charge transport measurements. In addition, its behavior as a resonant cavity has been investigated, as well as its properties as an energy generator. Therefore, it has been confirmed that the materials under study have properties that give them different application possibilities in various areas within the field of energy generation. / Segura Sanchis, E. (2024). Propiedades ópticas y eléctricas de monocristales de materiales híbridos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202755

No / The objective of this review is to provide an overview concerning what the authors believe to be the most important photoelectrochemical techniques for the study of semiconductor nanoparticles. After a short historical background and a brief introduction to the area of photoelectrochemistry, the working principles and experimental setups of the various static and dynamic techniques are presented. Experimental details which are of crucial importance for their correct execution are emphasized, and applications of the techniques as found in the recent research literature as applied to semiconductor nanoparticles are illustrated.

Dye sensitized solar cells (DSSCs) have typically been produced using organic liquids such as acetonitrile as the electrolyte solvent. In real world situations water can permeate into the cell through sealing materials and is also likely to be introduced during the fabrication process. This is a problem as the introduction of water into cells optimized to use an organic solvent tends to be detrimental to cell performance. In this work DSSCs which are optimized to use water as the main electrolyte solvent are produced and characterized. Optimization of aqueous DSSCs resulted in cells with efficiencies up to 3.5% being produced. In terms of characterization, it is generally seen in this work that aqueous DSSCs produce a lower photocurrent but similar photovoltage compared to DSSCs made using acetonitrile and reasons for this are examined in detail. The decreased ability of the aqueous electrolyte to wet the nanoporous TiO2 compared to an acetonitrile electrolyte is found to be a key difficulty and several possible solutions to this problem are examined. By measuring the photocurrent output of aqueous cells as a function of xy position it can be seen that there is some dye dissolution near to the electrolyte filling holes. This is thought to be linked to pH and the effect of 4-tert-butylpyridine and may also decrease the photocurrent. It is found that there is little difference between the two types of cells in terms of the conduction band position and the reaction of electrons in the semiconductor with triiodide in the electrolyte, explaining the similarity in photovoltage. By altering the pH of the electrolyte in an aqueous cell it is found to be possible to change the TiO2 conduction band position in the DSSC. This has a significant effect on the open circuit voltage and short circuit current of the cell, though the pH range available is limited by the fact that dye desorbs at high pH values.