Dissertations / Theses on the topic 'Ionization current'

It is desirable to measure engine performance for several reasons, e.g. when computing the spark advance setting in spark-ignited (SI) engines. There exists two methods, among others, of measuring the performance, such as measuring the pressure and the ionization current. Since the ionization current reflects the pressure, it is interesting to study if it is possible to extract information from the ionization current about the combustion and pressure. Three different algorithms for extracting information from the ionization current are studied. The first algorithm, ion peak, searches the \second peak" in the ionization signal. The second algorithm computes the centroid. In the third algorithm a model of the ionization signal structure is fitted to the ionization signal. The algorithms are tested in four operating conditions. The first algorithm uses the local information around the second peak and is sensitive to noise. The second algorithm uses a larger portion of the ionization signal, which is more stable. It provides promising results for engines with a clear post flame phase. The third algorithm, ion structure analysis, fits an ideal model to the ionization signal. The algorithm provides promising results, but the present implementation requires much computational effort.

This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were measured. This amplifier can also be cascaded to achieve very high gains similar to the photomultiplier tube but with much smaller size and no vacuum environment required. Testing was done by amplifying the output signal from an external silicon photodiode. Current gains over 600 were measured when two amplifying devices were cascaded. Additionally, the gain saturation phenomenon of the amplifier due to the space-charge effect is investigated. The measured gain saturation is observed to match very well with the theoretical based predictions. We also present a design rule for obtaining high current gain from the cascaded structure without experiencing gain saturation. Initial bandwidth of the SIM when connected to a silicon photodiode was measured to be about 300 kHz. As we replace the photodiode by a function generator, the bandwidth improved to 450 kHz which is the frequency limit of the system. These results were made on the first generation of SIM devices. We discovered that the space-charge resistance Rsc plays a significant role in determining frequency response. In future generations of the device, we can begin with optimizing the device geometry to reduce this resistance. Also, we can reduce the size of the metal pad and increase the oxide layer thickness to further minimize the device capacitance for faster response. Because of the low-noise gain mechanism employed, this device is of potential interest to a variety of fields requiring high-sensitivity optical or electronic detection.

For every operating condition of an internal combustion engine there exists an optimal spark timing, called maximum brake torque (MBT), which maximises the output torque and the efficiency of the engine. Traditionally MBT timing is implemented as an open-loop control where the ignition timing is found by using a combination of static lookup tables and sensor information. With a direct closed-loop control from the combustion process the performance of internal combustion engines could be improved. The thesis investigates if it is possible to estimate the MBT timing from the ionization current for every operating condition of a spark ignited engine where the operating conditions are defined by the engine parameters lambda, internal exhaust gas recirculation, engine load, engine speed and spark advance.

First an investigation of how much loss of torque an error from the MBT position corresponds to is made. Then the influence of the engine parameters on the shape of the ionization current was studied. Last different peak pressure position (PPP) estimating algorithms are presented and a new technique is developed where an engine operating point dependant part of the ionization current is used depending on the current operating condition of the engine. Two of the presented PPP estimating algorithms are then complemented with this technique and the results look promising.

Modelling combustion engines is an important tool in engine research. Development and modelling of ionization current has potential in developing virtual pressure sensors based on ionization measurements. Previous models has problem when predicting the true relationshipbetween the pressure peak location and ionization peak location, and both too early and too late predictions has been observed. An explanation for these discrepancies are provided and a model where the experimental mismatch has been reduced to less than one CAD is also presented. This is well within the measurement uncertainty.

Les variations de la composition des gaz naturels nécessitent un system de réglage automatique de la richesse de flamme pour des chaudières domestiques à gaz. Dans ce travail,deux solutions potentielles sont étudiées, à savoir la chimiluminescence de flamme et le courant d’ionisation. Des indicateurs de richesse sont déduits des signaux de chimiluminescence obtenus expérimentalement. L’impact de l’échange de chaleur entre la flamme et le brûleur sur des signaux de chimiluminescence est ensuite étudié. Une analyse est également faite des principaux facteurs pouvant perturber la caractérisation du signal de chimiluminescence. Le courant d’ionisation est ensuite étudié sur une flamme conique pour comprendre l’évolution de son intensité avec la position de sonde et avec les conditions de flamme. Il est montré ensuite que ces évolutions sont corrélées avec le changement de la distance entre la flamme et le brûleur. Enfin, une boucle de contrôle est développée pour démontrer la faisabilité d’un réglage automatique de richesse en exploitant le signal de chimiluminescence
The variations of natural gas composition call for an automatic equivalence ratio regulation system for domestic gas boilers. Two potential techniques for this purpose are investigated, i.e. the flame chemiluminescence and ionization current. Equivalence ratio indicators are inferred from the chemiluminescence signal based on the experiments. The investigation proceeds by examining effects of the flameburner heat exchange on the chemiluminescence signal. The interference of several disturbing factors for the chemiluminescence signal characterization is also analyzed. The flame ionization current is investigated on a conical flame to understand the evolution of its intensity with the probe position and flame conditions. These changes are then attributed to modifications of the distance between the flame base and the burner rim. Finally a control loop is developed to demonstrate the feasibility of equivalence ratio self-regulation with the chemiluminescence signal

Nesta dissertação é apresentado o estudo da célula SRAM estática de 6 transistores, com tecnologia CMOS, sendo utilizada em ambiente exposto à radiação. Foi verificado, através de simulação com o Hspice (HSPICE, 2009; KIME, 1998) e com a análise de Monte Carlo, o seu comportamento com relação à dose de ionização total (Total Ionization Dose, TID), a qual altera a tensão de limiar (threshold voltage, Vth) e a corrente de fuga, não sendo utilizada nenhuma técnica de fabricação especial para tolerância à radiação. Na simulação foi observado o comportamento da célula com relação ao tempo de atraso de escrita, à margem de ruído de leitura e ao consumo de energia. As simulações incluem as tecnologias de 130nm e 350nm sendo, portanto, possível comparar os efeitos de radiação citados em ambas, para verificar qual é a mais naturalmente resistente a radiação, verificando se está coerente com resultados divulgados na literatura. Para simular o efeito de dose, altera-se a tensão de limiar (threshold voltage, Vth) com a análise de Monte Carlo e, para a corrente de fuga, adiciona-se uma fonte de corrente entre o dreno e fonte de cada transistor. Os valores de Vth e corrente de fuga foram obtidos nas referências (HAUGERUD, 2005) para a tecnologia 130nm e (LACOE, 1998) para a tecnologia 350 nm. As simulações mostram que o comportamento foi coerente com resultados já conhecidos, em que a tecnologia mais antiga (350nm) tem alterações mais significativas do que a tecnologia mais atual, em relação à TID.
This work presents the study of the static RAM (SRAM) cell with 6 transistor, using CMOS technology, under radiation environment. The electrical behavior of the cell is evaluated using SPICE simulation (HSPICE, 2009; KIME, 1998) and applying Monte Carlo analysis. The effect of total ionization dose is analyzed through the modeling of threshold voltage shifts and leakage currents. The case study processes of this work do not use any special fabrication steps to make the circuit tolerant to radiation. The behavior of the cell related to write propagation time, read noise margin and energy consumption is evaluated through scripts written to support the simulation campaign. The simulations were performed for both 130nm and 350nm technologies, making possible to compare which one is more resistant to radiation. To further explore the dose effect in the case where the radiation does not affect all transistors in exactly the same way, the threshold voltage (Vth) of the transistors is varied randomly in the Monte Carlo analysis. To consider the leakage current, it is added a current source between drain and source of each transistor. The values of Vth and leakage current were obtained in reference (HAUGERUD, 2005) for the 130nm and in reference (LACOE, 1998) for the 350nm technology. The simulations show that the behavior was consistent with results already known, in which the older technology (350nm) is more significant changes then the most current technology, for the TID.

Les mémoires non-volatiles à grille flottante sont utilisées pour le stockage d'information sous la forme d'une charge électrique contenue dans la grille flottante d'un transistor. Le comportement de ces dispositifs mémoire est fortement lié aux propriétés de leur oxyde tunnel, qui permet à la fois le passage de cette charge lors d'opérations de programmation ainsi que sa rétention en l'absence d'alimentation électrique. Au cours de ce travail, des mesures de courant tunnel ont été réalisées sur des capacités semiconducteur-oxyde-semiconducteur de grande surface représentatives de la zone d'injection des cellules mémoire. L'application de pulses courts sur la grille de ces structures de test, au cours desquels le courant peut être mesuré en temps réel, a permis de mettre en évidence les principales propriétés transitoires et stationnaires pouvant affecter le fonctionnement des dispositifs mémoire. L'effet de la dégradation des oxydes tunnel, qui impacte le comportement des cellules mémoire lors des opérations de programmation et de la rétention, a été observé et interprété dans le cas d'un stress à tension constante. Les résultats obtenus sur les capacités de grande surface ont pu être utilisés dans le cadre d'une modélisation de cellules EEPROM
Floating gate non-volatile memory devices are used to store data under the form of an electric charge contained in the floating gate of a transistor. The behavior of these memory devices is strongly linked to the properties of their tunnel oxide, which allows the transit of this charge during write/erase operations as well as its retention while the transistor is not polarized. During this work, tunneling current measurements have been performed on large area semiconductor-oxide-semiconductor capacitors that are representative of the injection zone of memory cells. The application of short pulses to the gates of these test structures, during which the current can be measured as a function of time, allowed the observation of the main transient and steady-state properties that can affect the functioning of memory devices, The effect of tunnel oxide degradation, which impacts the behavior of memory cells during write/erase operations as well as data retention, has been observed and interpreted in the case of a constant voltage stress. The results obtained on large area capacitors have been used to model EEPROM cells

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Neste trabalho é realizada uma avaliação da resposta impulsiva de aterramento com haste concretada, considerando o efeito da ionização do solo. Para isso, o aterramento foi representado e simulado utilizando uma ferramenta computacional de simulação em três dimensões por meio do método dos elementos finitos. A representação computacional, bem como a validação da mesma, foi feita tomando-se como base dados experimentais apresentados na literatura. O fenômeno da ionização do solo foi implementado ponto a ponto, utilizando o equacionamento do modelo dinâmico de ionização do solo, possibilitando que aterramentos com diferentes formatos geométricos sejam avaliados. Avaliou-se a impedância transitória de uma haste concretada padronizada para solos com diferentes resistividades. Além disso, procedeu-se com uma análise da resposta impulsiva da haste concretada para diferentes parâmetros geométricos, a saber: raio do concreto envolvente, comprimento vertical da haste concretada, comprimento vertical do concreto envolvente e profundidade da haste concretada em relação ao nível do solo. Por fim, propõem-se limites práticos e sugestões de dimensões para a haste concretada, de forma que a reposta impulsiva seja otimizada.
In this research, was performed an impulsive response evaluation of concrete encased groundings, considering de soil ionization effect. In order to achive this, the grouding was represented and simulated in three dimensions using a finite element method software. The computational representation and validation were performed using experimental data presented in the literature. The soil ionization effect was implemented in a point form, allowing evaluate groudings with different geometric formats. It was studied the transient impedance of a standard concrete encased rod placed in soils with different resistivity values. Furthermore, was performed a transient response analysis for different geometric parameters of the concrete encased rod, namely: the concrete radius, the vertical length of the concrete encased rod, the vertical length of the concrete encased rod, the surrounding concrete and the depth of the concrete encased rod in relation to the soil surface. Finally, practical limits and suggested dimensions for the concrete encased rod are proposed, in order to optimize the impulse response.

Inspirés des technologies microélectroniques CMOS (Complementary Metal Oxide Semiconductor), les capteurs d’images CMOS sont largement utilisés dans de nombreuses applications grand public et prédominent sur le marché commercial des caméras intégrées. Au cours de la dernière décennie, de nombreuses avancées technologiques ont permis au capteur d’image CMOS d’atteindre d’excellentes performances ainsi qu’une faible consommation d’énergie. Par conséquent, ces imageurs deviennent des candidats essentiels pour un nombre croissant d’applications spatiales et nucléaires. Cependant, le comportement de ces dispositifs microélectroniques dans les environnements radiatifs nucléaires et spatiaux est encore mal compris. Par conséquent, il est nécessaire d’étudier les différents mécanismes qui conduisent à la dégradation des performances des capteurs d’images CMOS et en particulier à l’augmentation du courant d’obscurité, un signal parasite qui augmente avec les doses de radiations.Parmi ces doses de radiations, la dose dite de déplacement, relative à l’altération de la structure cristalline du silicium, reste peu étudiée par rapport à la dose dite ionisante. Dans les dernières technologies de capteurs d’images CMOS utilisant des photodiodes pincées, la dose ionisante n’est plus le mécanisme de dégradation dominant dès lors que la dose de déplacement est mise en jeu. La dose de déplacement devient le mécanisme de dégradation principal qui conduit à l’augmentation du courant d’obscurité. Ce travail se concentre principalement sur le rôle des défauts cristallins, créés par la dose de déplacement induits par les radiations, dans l’augmentation du courant d’obscurité des capteurs d’images CMOS. Un intérêt particulier est accordé aux défauts métastables qui sont probablement la cause des fluctuations discrètes et aléatoires du courant d’obscurité appelé : signal des télégraphistes. Cette étude présente un double enjeu :Le premier vise à contribuer à l’amélioration des connaissances des principes physiques mis en jeu dans le silicium cristallin face aux radiations. Les interactions particule-matière,associées à l’architecture spécifique des capteurs d’images, visent à fournir des outils fiables pour l’analyse des défauts induits par les radiations dans le silicium. Ces observations et résultats peuvent être étendus à tous les dispositifs à base de silicium et plus généralement aux autres dispositifs à semi conducteurs.Le second vise à identifier les différents mécanismes conduisant à l’augmentation du courant d’obscurité des capteurs d’images CMOS lorsqu’ils fonctionnent dans des environnements radiatifs. L’étude vise à identifier et à améliorer la connaissance des comportements des sources de courant d’obscurité dans le but d’optimiser les capteurs d’images CMOS pour les futures applications spatiales et nucléaires
Inspired by the microelectronic Complementary Metal Oxide Semiconductor (CMOS) technologies, CMOS image sensors are widely used in many consumer-grade applications and are predominant in the commercial market for embedded cameras. Over the past decade,numerous technological advances allowed state-of-the-art CMOS image sensors to achieve excellent performances as well as low-power consumption. Therefore, CMOS image sensors are becoming essential candidates for a growing number of high-end applications such as space and nuclear applications. However, the behavior of these microelectronic devices inspace and nuclear radiative environments is still under understanding. Hence, studies still investigate the different mechanisms that lead to the degradation of CMOS image sensor performances including the radiation-induced dark current increase, a parasitic signal that increases with radiation doses. Among these radiation doses, the so-called displacement dose,relative to the alteration of the crystalline structure of the silicon, remains poorly studied compared to the so-called ionizing dose. In the latest CMOS image sensor technologies using pinned photodiodes, the ionizing dose is no longer the main degradation mechanism when the displacement dose is at stake. From then on, the displacement dose becomes the principal degradation mechanism that leads to the dark current increase. This work mainly focuses onthe role of the crystalline defects, created by radiation-induced displacement damage, in the CMOS image sensor dark current increase. Particular interest is given to metastable defects,which are probably the cause of discrete and random fluctuations of the dark current called : Dark Current Random Telegraph Signal (DC-RTS). This study presents a double objective :The first aims to contribute to improving knowledge of the physical principles involved in crystalline silicon when facing radiations. Particle-matter interactions, combined with the specific architecture of image sensors, aim to provide reliable tools to analyze the radiation induced defects in silicon. Observations and findings can be extended to all silicon-based devices and more generally to other semiconductor-based devices.The second seeks to identify the different mechanisms leading to CMOS image sensor dark current increase when operating in radiative environments. The study aims to identify and improve knowledge on the behavior of dark current sources aiming to optimize CMOS image sensors for future space and nuclear applications

Studies of Radiation-Induced Conductivity (RIC) in the Teflon film of a radiation-charged electret ionization chamber (EIC) are discussed. An EIC measures dose from the amount of electret surface charge neutralized by ions created in the chamber's sensitive volume. A semi-empirical equation is presented for the calculation of prompt time-dependent RIC as a function of air-kerma rate and electric field. Measurements showing the dependence of radiation-induced current on electrode material show a tenfold difference in current between aluminum and graphite electrodes. RIC permits charge migration through the polymer which can cause an overestimation of dose. Intermittently heating and charging the electret will cause surface charges to be deposited at deep energy levels and therefore improving electret charge retention. This study demonstrates the influence of radiation induced currents on the performance of the radiation-charged RIC.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

La methode est utilisee pour l'etude de la densite d'etats dans la bande interdite du silicium amorphe hydrogene et sur cdin::(2)s::(4). La caracterisation des niveaux ayant des energies d'ionisation thermique entre 0,1 ev et 0,9 ev, le modele de transfert de charge decrivant l'effet photorefractif et l'evaluation du niveau de recombinaison, sont faits dans le materiau photorefractif. Les effets du dopage (fer) et du codopage (fer, vanadium) sur les niveaux sont consideres. Le centre responsable de la capture d'electrons est aussi etudie par absorption optique et photoconductivite photoinduites. Les resultats s'accordent avec ceux des mesures de photorefractivite

Le carbure de silicium (SiC) possède plusieurs propriétés exceptionnelles comme une large bande interdite, un champ électrique critique et une vitesse de saturation des porteurs élevée pour remplacer le silicium (Si) dans des domaines de fonctionnement jusque-là inaccessibles avec le Si. Un nombre important de démonstrateurs des composants de puissance en SiC faisant état de performances remarquables ainsi que la disponibilité commerciale des composants en SiC confirment la maturité de la filière SiC et montrent les progrès technologiques réalisés au cours des dernières années. Cependant, il existe peu d'études sur les coefficients d'ionisation du SiC, lesquels sont pourtant indispensables pour prévoir précisément la tenue en tension des composants de puissance en SiC. Ce travail contribue donc à mieux déterminer ces coefficients. Pour cela, un bon nombre de diodes spécialement conçues pour la détermination des coefficients d'ionisation du SiC par la technique OBIC (Optical Beam Induced Current) ont été réalisées sur différents wafers de SiC-4H et de SiC-6H, deux polytypes courant du SiC. Cette technique repose sur un faisceau de laser ultraviolet qui génère des paires électrons-trous dans la zone de charge d'espace d'une diode sous test. La mesure du courant résultant permet d'accéder aux coefficients d'ionisation. A partir des mesures OBIC sur les diodes réalisées, nous avons pu déduire les coefficients pour ces deux polytypes du SiC. Plus particulièrement, les coefficients d'ionisation du SiC-4H sont déterminés dans une large gamme de champ électrique grâce aux mesures sur les différents dopages. Les paramètres des coefficients déterminés dans ce travail peuvent être utilisés en conception de dispositifs haute tension pour prédire plus précisément l'efficacité de leur protection périphérique.

Les plantes médicinales constituent une source inexhaustible de composés (des produits naturels - PN) utilisé en médecine pour la prévention et le traitement de diverses maladies. L'introduction de nouvelles technologies et méthodes dans le domaine de la chimie des produits naturels a permis le développement de méthodes ‘high throughput’ pour la détermination de la composition chimique des extraits de plantes, l'évaluation de leurs propriétés et l'exploration de leur potentiel en tant que candidats médicaments. Dernièrement, la métabolomique, une approche intégrée incorporant les avantages des technologies d'analyse moderne et la puissance de la bioinformatique s’est révélé un outil efficace dans la biologie des systèmes. En particulier, l'application de la métabolomique pour la découverte de nouveaux composés bioactifs constitue un domaine émergent dans la chimie des produits naturels. Dans ce contexte, le genre Acronychia de la famille des Rutaceae a été choisi sur la base de son usage en médecine traditionnelle pour ses propriétés antimicrobienne, antipyrétique, antispasmodique et anti-inflammatoire. Nombre de méthodes chromatographiques modernes, spectrométriques et spectroscopiques sont utilisées pour l'exploration de leur contenu en métabolites suivant trois axes principaux constituant les trois chapitres de cette thèse. En bref, le premier chapitre décrit l’étude phytochimique d’Acronychia pedunculata, l’identification des métabolites secondaires contenus dans cette espèce et l'évaluation de leurs propriétés biologiques. Le deuxième chapitre vise au développement de méthodes analytiques pour l'identification des dimères d’acétophénones (marqueurs chimiotaxonomiques du genre) et aux stratégies utilisées pour la déréplication de ces différents extraits et la caractérisation chimique des composés par UHPLC-HRMSn. Le troisième chapitre se concentre sur l'application de méthodologies métabolomique (RMN et LC-MS) pour l'analyse comparative (entre les différentes espèces, origines, organes), pour des études chimiotaxonomiques (entre les espèces) et pour la corrélation des composés contenus avec une activité pharmacologique
Medicinal plants constitute an unfailing source of compounds (natural products – NPs) utilised in medicine for the prevention and treatment of various deceases. The introduction of new technologies and methods in the field of natural products chemistry enabled the development of high throughput methodologies for the chemical composition determination of plant extracts, evaluation of their properties and the exploration of their potentials as drug candidates. Lately, metabolomics, an integrated approach incorporating the advantages of modern analytical technologies and the power of bioinformatics has been proven an efficient tool in systems biology. In particular, the application of metabolomics for the discovery of new bioactive compounds constitutes an emerging field in natural products chemistry. In this context, Acronychia genus of Rutaceae family was selected based on its well-known traditional use as antimicrobial, antipyretic, antispasmodic and anti-inflammatory therapeutic agent. Modern chromatographic, spectrometric and spectroscopic methods were utilised for the exploration of their metabolite content following three basic axes constituting the three chapters of this thesis. Briefly, the first chapter describes the phytochemical investigation of Acronychia pedunculata, the identification of secondary metabolites contained in this species and evaluation of their biological properties. The second chapter refers to the development of analytical methods for the identification of acetophenones (chemotaxonomic markers of the genus) and to the dereplication strategies for the chemical characterisation of extracts by UHPLC-HRMSn. The third chapter focuses on the application of metabolomic methodologies (LC-MS & NMR) for comparative analysis (between different species, origins, organs), chemotaxonomic studies (between species) and compound-activity correlations

Organic semiconductors are a new key technology for large-area and flexible thin-film electronics. They are deposited as thin films (sub-nanometer to micrometer) on large-area substrates. The technologically most advanced applications are organic light emitting diodes (OLEDs) and organic photovoltaics (OPV). For the improvement of performance and efficiency, correct modeling of the electronic processes in the devices is essential. Reliable characterization and validation of the electronic properties of the materials is simultaneously required for the successful optimization of devices. Furthermore, understanding the relations between material structures and their key characteristics opens the path for innovative material and device design. In this thesis, two material characterization methods are developed, respectively refined and applied: a novel technique for measuring the charge carrier mobility μ and a way to determine the ionization energy IE or the electron affinity EA of an organic semiconductor. For the mobility measurements, a new evaluation approach for space-charge limited current (SCLC) measurements in single carrier devices is developed. It is based on a layer thickness variation of the material under investigation. In the \"potential mapping\" (POEM) approach, the voltage as a function of the device thickness V(d) at a given current density is shown to coincide with the spatial distribution of the electric potential V(x) in the thickest device. On this basis, the mobility is directly obtained as function of the electric field F and the charge carrier density n. The evaluation is model-free, i.e. a model for μ(F, n) to fit the measurement data is not required, and the measurement is independent of a possible injection barrier or potential drop at non-optimal contacts. The obtained μ(F, n) function describes the effective average mobility of free and trapped charge carriers. This approach realistically describes charge transport in energetically disordered materials, where a clear differentiation between trapped and free charges is impossible or arbitrary. The measurement of IE and EA is performed by characterizing solar cells at varying temperature T. In suitably designed devices based on a bulk heterojunction (BHJ), the open-circuit voltage Voc is a linear function of T with negative slope in the whole measured range down to 180K. The extrapolation to temperature zero V0 = Voc(T → 0K) is confirmed to equal the effective gap Egeff, i.e. the difference between the EA of the acceptor and the IE of the donor. The successive variation of different components of the devices and testing their influence on V0 verifies the relation V0 = Egeff. On this basis, the IE or EA of a material can be determined in a BHJ with a material where the complementary value is known. The measurement is applied to a number of material combinations, confirming, refining, and complementing previously reported values from ultraviolet photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES). These measurements are applied to small molecule organic semiconductors, including mixed layers. In blends of zinc-phthalocyanine (ZnPc) and C60, the hole mobility is found to be thermally and field activated, as well as increasing with charge density. Varying the mixing ratio, the hole mobility is found to increase with increasing ZnPc content, while the effective gap stays unchanged. A number of further materials and material blends are characterized with respect to hole and electron mobility and the effective gap, including highly diluted donor blends, which have been little investigated before. In all materials, a pronounced field activation of the mobility is observed. The results enable an improved detailed description of the working principle of organic solar cells and support the future design of highly efficient and optimized devices
Organische Halbleiter sind eine neue Schlüsseltechnologie für großflächige und flexible Dünnschichtelektronik. Sie werden als dünne Materialschichten (Sub-Nanometer bis Mikrometer) auf großflächige Substrate aufgebracht. Die technologisch am weitesten fortgeschrittenen Anwendungen sind organische Leuchtdioden (OLEDs) und organische Photovoltaik (OPV). Zur weiteren Steigerung von Leistungsfähigkeit und Effizienz ist die genaue Modellierung elektronischer Prozesse in den Bauteilen von grundlegender Bedeutung. Für die erfolgreiche Optimierung von Bauteilen ist eine zuverlässige Charakterisierung und Validierung der elektronischen Materialeigenschaften gleichermaßen erforderlich. Außerdem eröffnet das Verständnis der Zusammenhänge zwischen Materialstruktur und -eigenschaften einen Weg für innovative Material- und Bauteilentwicklung. Im Rahmen dieser Dissertation werden zwei Methoden für die Materialcharakterisierung entwickelt, verfeinert und angewandt: eine neuartige Methode zur Messung der Ladungsträgerbeweglichkeit μ und eine Möglichkeit zur Bestimmung der Ionisierungsenergie IE oder der Elektronenaffinität EA eines organischen Halbleiters. Für die Beweglichkeitsmessungen wird eine neue Auswertungsmethode für raumladungsbegrenzte Ströme (SCLC) in unipolaren Bauteilen entwickelt. Sie basiert auf einer Schichtdickenvariation des zu charakterisierenden Materials. In einem Ansatz zur räumlichen Abbildung des elektrischen Potentials (\"potential mapping\", POEM) wird gezeigt, dass das elektrische Potential als Funktion der Schichtdicke V(d) bei einer gegebenen Stromdichte dem räumlichen Verlauf des elektrischen Potentials V(x) im dicksten Bauteil entspricht. Daraus kann die Beweglichkeit als Funktion des elektrischen Felds F und der Ladungsträgerdichte n berechnet werden. Die Auswertung ist modellfrei, d.h. ein Modell zum Angleichen der Messdaten ist für die Berechnung von μ(F, n) nicht erforderlich. Die Messung ist außerdem unabhängig von einer möglichen Injektionsbarriere oder einer Potentialstufe an nicht-idealen Kontakten. Die gemessene Funktion μ(F, n) beschreibt die effektive durchschnittliche Beweglichkeit aller freien und in Fallenzuständen gefangenen Ladungsträger. Dieser Zugang beschreibt den Ladungstransport in energetisch ungeordneten Materialien realistisch, wo eine klare Unterscheidung zwischen freien und Fallenzuständen nicht möglich oder willkürlich ist. Die Messung von IE und EA wird mithilfe temperaturabhängiger Messungen an Solarzellen durchgeführt. In geeigneten Bauteilen mit einem Mischschicht-Heteroübergang (\"bulk heterojunction\" BHJ) ist die Leerlaufspannung Voc im gesamten Messbereich oberhalb 180K eine linear fallende Funktion der Temperatur T. Es kann bestätigt werden, dass die Extrapolation zum Temperaturnullpunkt V0 = Voc(T → 0K) mit der effektiven Energielücke Egeff , d.h. der Differenz zwischen EA des Akzeptor-Materials und IE des Donator-Materials, übereinstimmt. Die systematische schrittweise Variation einzelner Bestandteile der Solarzellen und die Überprüfung des Einflusses auf V0 bestätigen die Beziehung V0 = Egeff. Damit kann die IE oder EA eines Materials bestimmt werden, indem man es in einem BHJ mit einem Material kombiniert, dessen komplementärer Wert bekannt ist. Messungen per Ultraviolett-Photoelektronenspektroskopie (UPS) und inverser Photoelektronenspektroskopie (IPES) werden damit bestätigt, präzisiert und ergänzt. Die beiden entwickelten Messmethoden werden auf organische Halbleiter aus kleinen Molekülen einschließlich Mischschichten angewandt. In Mischschichten aus Zink-Phthalocyanin (ZnPc) und C60 wird eine Löcherbeweglichkeit gemessen, die sowohl thermisch als auch feld- und ladungsträgerdichteaktiviert ist. Wenn das Mischverhältnis variiert wird, steigt die Löcherbeweglichkeit mit zunehmendem ZnPc-Anteil, während die effektive Energielücke unverändert bleibt. Verschiedene weitere Materialien und Materialmischungen werden hinsichtlich Löcher- und Elektronenbeweglichkeit sowie ihrer Energielücke charakterisiert, einschließlich bisher wenig untersuchter hochverdünnter Donator-Systeme. In allen Materialien wird eine deutliche Feldaktivierung der Beweglichkeit beobachtet. Die Ergebnisse ermöglichen eine verbesserte Beschreibung der detaillierten Funktionsweise organischer Solarzellen und unterstützen die künftige Entwicklung hocheffizienter und optimierter Bauteile

碩士
國立中正大學
化學暨生物化學研究所
104
In the early 80’s, John Fenn proposed and described how to use direct current ( dc ) electrospray ionization ( ESI ) mass spectrometry for identification and analysis of biological macromolecules, and confirmed that biological molecules such as proteins formed multiple charged gaseous ions. Researchers have investigated direct current electrospray ionization thoroughly for decades. In comparison, the research of the alternating current ( ac ) electrospray ionization, especially at high frequency range ( ≧ 100 kHz ) that can enhance signal intensity, has not been investigated until recent years. High mobility protons migrated back and forth between the Taylor cone tip and the bulk, whereas the protonated samples with low mobility remained inside the Taylor cone before aerosol ejection for ionization during each ac cycle. This study uses two large molecular weight proteins ( myoglobin and cytochrome c ) to explore the novel mechanism of alternating current electrospray ionization. Myoglobin dissolved in ammonium acetate solution adjusted various pH conditions by adding ammonia, have been studied at various frequencies ( 50 kHz，150 kHz，and 250 kHz ) of applied ac voltage. Under high frequency ( 250 kHz ) the charge state distributions do not change at different pH conditions. These observations are considerably different from the mass spectra obtained using dc voltage and are due to high temperature in ac ESI droplets. The high temperature effects denature myoglobin regardless pH conditions. We also examined the ESI spectrum using supercharging reagents of different concentrations including m-NBA，sulfolane，and glycerol of the same pH, and observed that charge state increase at dc ESI but unchanged states at ac ESI. We also investigated cytochrome c and found that charge state distributions were unchanged at ac ESI in low pH range.

碩士
國立中正大學
化學暨生物化學研究所
105
Traditionally, mass spectrometry (MS) analysis usually used electrospray ionization (ESI) by applying a high voltage direct current (DC) electric field to the capillary needle to achieve the effect of ionization. However, its ionization efficiency and protein charge distribution easily transformed by the solution pH values and compositions. Although many scholars have a considerable degree of understanding of DC ESI, high frequency (> 100 kHz) alternating current (AC) ESI for mass spectrometer analysis and discussions is developed in recent years. The mechanism can be understood by examining the two AC half cycles, the anodic half cycle and cathodic half cycle, separately. During the complete AC cycle, the time required for two half cycles to convert the electric field is very short, so the low mobility protein ions can be accumulated at the tip. Due to the angle of the Taylor cone formed by AC ESI (~12°) is smaller than DC ESI (~49°), and the AC droplets are also smaller than DC droplets, so the ions can be directly desorbed from the droplets. At the appropriate high frequency, the spectrum obtained by AC ESI does not change with the compositions of the solution, which is quite different from the DC ESI. This phenomenon should be related to the high temperature effect caused by the AC ESI mechanism. In this study, we used two different thermal stability protein including the high thermal stability cytochrome c and the low thermal stability myoglobin to observe the differences of the charge state distribution of protein between DC ESI and AC ESI mechanism. In the part of the high thermal stability cytochrome c, we investigated the mass spectra of the charge state distributions at three pH values, pH 3.8, pH 2.8, and pH 2.3 with various organic solvent conditions (acetonitrile 0% and 30% (v/v)) and different AC output voltage by using AC ESI at frequencies in the hundreds of kilohertz (> 100 kHz) to observe the differences of the mass spectra between DC ESI and AC ESI and the protein conformation. The experimental results indicated that the DC ESI spectra would change with the various solution compositions. In contrast, the spectra under AC ESI especially applied the high voltage which would not change with the solution conditions and we observed that the charge distribution of the cytochrome c has a tendency to move toward a low charge state (high m/z). We speculated the reason is the high temperature effect increases the gas phase water molecules which with the protein ions to compete the proton that resulted in decreasing the charge of the analyte and the protein conformation transformed to a relatively tight and folded native conformation. The mass spectra of the low thermal stability myoglobin are at pH 4, pH 7, pH 8 in ammonium acetate buffer solutions and which pH 7 with various organic solvent conditions (acetonitrile 0% and 30% (v/v)) also observed the different myoglobin conformation between DC ESI and AC ESI. The results indicated AC ESI would make myoglobin denature due to the high temperature effect, and DC ESI would let myoglobin conformation change with the solution conditions.

In laser wakefield acceleration, an ultra-short high-intensity laser pulse excites a plasma wave, which can sustain accelerating electric fields of several hundred GV/m. This scheme advances a novel concept for compact and less expensive electron accelerators, which can be hosted in a typical university size laboratory. Furthermore, laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer size with duration ranging from several fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top X-ray light-sources and remains a big challenge due to the resolution limit of existing diagnostic techniques. Spectral measurement of broadband coherent and incoherent transition radiation (TR) produced when electron bunches passing through a metal foil is a promising way to analyze longitudinal characteristics of these bunches. Due to the limited reproducibility of the electron source this measurement highly requires single-shot capability. An ultra-broadband spectrometer combines the TR spectrum in UV/NIR (200-1000 nm), NIR (0.9-1.7 µm) and mid-IR (1.6-12 µm). A high spectral sensitivity, dynamic bandwidth and spectral resolution are realized by three optimized dispersion and detection systems integrated into a single-shot spectrometer. A complete characterization and calibration of the spectrometer have been done concerning wavelengths, relative spectral sensitivities, and absolute photometric sensitivities, also taking into account for the light polarization. The TR spectrometer is able to characterize electron bunches with charges as low as 1pC and can resolve time-scales of 0.4 fs. Electron bunches up to 16 fs (rms width) can be reconstructed from their TR spectrum. In the presented work, the self-truncated ionization induced injection (STII) scheme has been explored to study the relevant beam parameters especially its longitudinal bunch profile and the resulting peak current.

Organic semiconductors are a new key technology for large-area and flexible thin-film electronics. They are deposited as thin films (sub-nanometer to micrometer) on large-area substrates. The technologically most advanced applications are organic light emitting diodes (OLEDs) and organic photovoltaics (OPV). For the improvement of performance and efficiency, correct modeling of the electronic processes in the devices is essential. Reliable characterization and validation of the electronic properties of the materials is simultaneously required for the successful optimization of devices. Furthermore, understanding the relations between material structures and their key characteristics opens the path for innovative material and device design. In this thesis, two material characterization methods are developed, respectively refined and applied: a novel technique for measuring the charge carrier mobility μ and a way to determine the ionization energy IE or the electron affinity EA of an organic semiconductor. For the mobility measurements, a new evaluation approach for space-charge limited current (SCLC) measurements in single carrier devices is developed. It is based on a layer thickness variation of the material under investigation. In the \"potential mapping\" (POEM) approach, the voltage as a function of the device thickness V(d) at a given current density is shown to coincide with the spatial distribution of the electric potential V(x) in the thickest device. On this basis, the mobility is directly obtained as function of the electric field F and the charge carrier density n. The evaluation is model-free, i.e. a model for μ(F, n) to fit the measurement data is not required, and the measurement is independent of a possible injection barrier or potential drop at non-optimal contacts. The obtained μ(F, n) function describes the effective average mobility of free and trapped charge carriers. This approach realistically describes charge transport in energetically disordered materials, where a clear differentiation between trapped and free charges is impossible or arbitrary. The measurement of IE and EA is performed by characterizing solar cells at varying temperature T. In suitably designed devices based on a bulk heterojunction (BHJ), the open-circuit voltage Voc is a linear function of T with negative slope in the whole measured range down to 180K. The extrapolation to temperature zero V0 = Voc(T → 0K) is confirmed to equal the effective gap Egeff, i.e. the difference between the EA of the acceptor and the IE of the donor. The successive variation of different components of the devices and testing their influence on V0 verifies the relation V0 = Egeff. On this basis, the IE or EA of a material can be determined in a BHJ with a material where the complementary value is known. The measurement is applied to a number of material combinations, confirming, refining, and complementing previously reported values from ultraviolet photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES). These measurements are applied to small molecule organic semiconductors, including mixed layers. In blends of zinc-phthalocyanine (ZnPc) and C60, the hole mobility is found to be thermally and field activated, as well as increasing with charge density. Varying the mixing ratio, the hole mobility is found to increase with increasing ZnPc content, while the effective gap stays unchanged. A number of further materials and material blends are characterized with respect to hole and electron mobility and the effective gap, including highly diluted donor blends, which have been little investigated before. In all materials, a pronounced field activation of the mobility is observed. The results enable an improved detailed description of the working principle of organic solar cells and support the future design of highly efficient and optimized devices.:1. Introduction 2. Organic semiconductors and devices 2.1. Organic semiconductors 2.1.1. Conjugated π system 2.1.2. Small molecules and polymers 2.1.3. Disorder in amorphous materials 2.1.4. Polarons 2.1.5. Polaron hopping 2.1.6. Fermi-Dirac distribution and Fermi level 2.1.7. Quasi-Fermi levels 2.1.8. Trap states 2.1.9. Doping 2.1.10. Excitons 2.2. Interfaces and blend layers 2.2.1. Interface dipoles 2.2.2. Energy level bending 2.2.3. Injection from metal into semiconductor, and extraction 2.2.4. Excitons at interfaces 2.3. Charge transport and recombination in organic semiconductors 2.3.1. Drift transport 2.3.2. Charge carrier mobility 2.3.3. Thermally activated transport 2.3.4. Diffusion transport 2.3.5. Drift-diffusion transport 2.3.6. Space-charge limited current 2.3.7. Recombination 2.4. Mobility measurement 2.4.1. SCLC and TCLC 2.4.2. Time of flight 2.4.3. Organic field effect transistors 2.4.4. CELIV 2.5. Organic solar cells 2.5.1. Exciton diffusion towards the interface 2.5.2. Dissociation of CT states 2.5.3. CT recombination 2.5.4. Flat and bulk heterojunction 2.5.5. Transport layers 2.5.6. Thin film optics 2.5.7. Current-voltage characteristics and equivalent circuit 2.5.8. Solar cell efficiency 2.5.9. Limits of efficiency 2.5.10. Correct solar cell characterization 2.5.11. The \"O-Factor\" 3. Materials and experimental methods 3.1. Materials 3.2. Device fabrication and layout 3.2.1. Layer deposition 3.2.2. Encapsulation 3.2.3. Homogeneity of layer thickness on a wafer 3.2.4. Device layout 3.3. Characterization 3.3.1. Electrical characterization 3.3.2. Sample illumination 3.3.3. Temperature dependent characterization 3.3.4. UPS 4. Simulations 5.1. Design of single carrier devices 5.1.1. General design requirements 5.1.2. Single carrier devices for space-charge limited current 5.1.3. Ohmic regime 5.1.4. Design of injection and extraction layers 5.2. Advanced evaluation of SCLC – potential mapping 5.2.1. Potential mapping by thickness variation 5.2.2. Further evaluation of the transport profile 5.2.3. Injection into and extraction from single carrier devices 5.2.4. Majority carrier approximation 5.3. Proof of principle: POEM on simulated data 5.3.1. Constant mobility 5.3.2. Field dependent mobility 5.3.3. Field and charge density activated mobility 5.3.4. Conclusion 5.4. Application: Transport characterization in organic semiconductors 5.4.1. Hole transport in ZnPc:C60 5.4.2. Hole transport in ZnPc:C60 – temperature variation 5.4.3. Hole transport in ZnPc:C60 – blend ratio variation 5.4.4. Hole transport in ZnPc:C70 5.4.5. Hole transport in neat ZnPc 5.4.6. Hole transport in F4-ZnPc:C60 5.4.7. Hole transport in DCV-5T-Me33:C60 5.4.8. Electron transport in ZnPc:C60 5.4.9. Electron transport in neat Bis-HFl-NTCDI 5.5. Summary and discussion of the results 5.5.1. Phthalocyanine:C60 blends 5.5.2. DCV-5T-Me33:C60 5.5.3. Conclusion 6. Organic solar cell characteristics: the influence of temperature 6.1. ZnPc:C60 solar cells 6.1.1. Temperature variation 6.1.2. Illumination intensity variation 6.2. Voc in flat and bulk heterojunction organic solar cells 6.2.1. Qualitative difference in Voc(I, T) 6.2.2. Interpretation of Voc(I, T) 6.3. BHJ stoichiometry variation 6.3.1. Voc upon variation of stoichiometry and contact layer 6.3.2. V0 upon stoichiometry variation 6.3.3. Low donor content stoichiometry 6.3.4. Conclusion from stoichiometry variation 6.4. Transport material variation 6.4.1. HTM variation 6.4.2. ETM variation 6.5. Donor:acceptor material variation 6.5.1. Donor variation 6.5.2. Acceptor variation 6.6. Conclusion 7. Summary and outlook 7.1. Summary 7.2. Outlook A. Appendix A.1. Energy pay-back of this thesis A.2. Tables and registers
Organische Halbleiter sind eine neue Schlüsseltechnologie für großflächige und flexible Dünnschichtelektronik. Sie werden als dünne Materialschichten (Sub-Nanometer bis Mikrometer) auf großflächige Substrate aufgebracht. Die technologisch am weitesten fortgeschrittenen Anwendungen sind organische Leuchtdioden (OLEDs) und organische Photovoltaik (OPV). Zur weiteren Steigerung von Leistungsfähigkeit und Effizienz ist die genaue Modellierung elektronischer Prozesse in den Bauteilen von grundlegender Bedeutung. Für die erfolgreiche Optimierung von Bauteilen ist eine zuverlässige Charakterisierung und Validierung der elektronischen Materialeigenschaften gleichermaßen erforderlich. Außerdem eröffnet das Verständnis der Zusammenhänge zwischen Materialstruktur und -eigenschaften einen Weg für innovative Material- und Bauteilentwicklung. Im Rahmen dieser Dissertation werden zwei Methoden für die Materialcharakterisierung entwickelt, verfeinert und angewandt: eine neuartige Methode zur Messung der Ladungsträgerbeweglichkeit μ und eine Möglichkeit zur Bestimmung der Ionisierungsenergie IE oder der Elektronenaffinität EA eines organischen Halbleiters. Für die Beweglichkeitsmessungen wird eine neue Auswertungsmethode für raumladungsbegrenzte Ströme (SCLC) in unipolaren Bauteilen entwickelt. Sie basiert auf einer Schichtdickenvariation des zu charakterisierenden Materials. In einem Ansatz zur räumlichen Abbildung des elektrischen Potentials (\"potential mapping\", POEM) wird gezeigt, dass das elektrische Potential als Funktion der Schichtdicke V(d) bei einer gegebenen Stromdichte dem räumlichen Verlauf des elektrischen Potentials V(x) im dicksten Bauteil entspricht. Daraus kann die Beweglichkeit als Funktion des elektrischen Felds F und der Ladungsträgerdichte n berechnet werden. Die Auswertung ist modellfrei, d.h. ein Modell zum Angleichen der Messdaten ist für die Berechnung von μ(F, n) nicht erforderlich. Die Messung ist außerdem unabhängig von einer möglichen Injektionsbarriere oder einer Potentialstufe an nicht-idealen Kontakten. Die gemessene Funktion μ(F, n) beschreibt die effektive durchschnittliche Beweglichkeit aller freien und in Fallenzuständen gefangenen Ladungsträger. Dieser Zugang beschreibt den Ladungstransport in energetisch ungeordneten Materialien realistisch, wo eine klare Unterscheidung zwischen freien und Fallenzuständen nicht möglich oder willkürlich ist. Die Messung von IE und EA wird mithilfe temperaturabhängiger Messungen an Solarzellen durchgeführt. In geeigneten Bauteilen mit einem Mischschicht-Heteroübergang (\"bulk heterojunction\" BHJ) ist die Leerlaufspannung Voc im gesamten Messbereich oberhalb 180K eine linear fallende Funktion der Temperatur T. Es kann bestätigt werden, dass die Extrapolation zum Temperaturnullpunkt V0 = Voc(T → 0K) mit der effektiven Energielücke Egeff , d.h. der Differenz zwischen EA des Akzeptor-Materials und IE des Donator-Materials, übereinstimmt. Die systematische schrittweise Variation einzelner Bestandteile der Solarzellen und die Überprüfung des Einflusses auf V0 bestätigen die Beziehung V0 = Egeff. Damit kann die IE oder EA eines Materials bestimmt werden, indem man es in einem BHJ mit einem Material kombiniert, dessen komplementärer Wert bekannt ist. Messungen per Ultraviolett-Photoelektronenspektroskopie (UPS) und inverser Photoelektronenspektroskopie (IPES) werden damit bestätigt, präzisiert und ergänzt. Die beiden entwickelten Messmethoden werden auf organische Halbleiter aus kleinen Molekülen einschließlich Mischschichten angewandt. In Mischschichten aus Zink-Phthalocyanin (ZnPc) und C60 wird eine Löcherbeweglichkeit gemessen, die sowohl thermisch als auch feld- und ladungsträgerdichteaktiviert ist. Wenn das Mischverhältnis variiert wird, steigt die Löcherbeweglichkeit mit zunehmendem ZnPc-Anteil, während die effektive Energielücke unverändert bleibt. Verschiedene weitere Materialien und Materialmischungen werden hinsichtlich Löcher- und Elektronenbeweglichkeit sowie ihrer Energielücke charakterisiert, einschließlich bisher wenig untersuchter hochverdünnter Donator-Systeme. In allen Materialien wird eine deutliche Feldaktivierung der Beweglichkeit beobachtet. Die Ergebnisse ermöglichen eine verbesserte Beschreibung der detaillierten Funktionsweise organischer Solarzellen und unterstützen die künftige Entwicklung hocheffizienter und optimierter Bauteile.:1. Introduction 2. Organic semiconductors and devices 2.1. Organic semiconductors 2.1.1. Conjugated π system 2.1.2. Small molecules and polymers 2.1.3. Disorder in amorphous materials 2.1.4. Polarons 2.1.5. Polaron hopping 2.1.6. Fermi-Dirac distribution and Fermi level 2.1.7. Quasi-Fermi levels 2.1.8. Trap states 2.1.9. Doping 2.1.10. Excitons 2.2. Interfaces and blend layers 2.2.1. Interface dipoles 2.2.2. Energy level bending 2.2.3. Injection from metal into semiconductor, and extraction 2.2.4. Excitons at interfaces 2.3. Charge transport and recombination in organic semiconductors 2.3.1. Drift transport 2.3.2. Charge carrier mobility 2.3.3. Thermally activated transport 2.3.4. Diffusion transport 2.3.5. Drift-diffusion transport 2.3.6. Space-charge limited current 2.3.7. Recombination 2.4. Mobility measurement 2.4.1. SCLC and TCLC 2.4.2. Time of flight 2.4.3. Organic field effect transistors 2.4.4. CELIV 2.5. Organic solar cells 2.5.1. Exciton diffusion towards the interface 2.5.2. Dissociation of CT states 2.5.3. CT recombination 2.5.4. Flat and bulk heterojunction 2.5.5. Transport layers 2.5.6. Thin film optics 2.5.7. Current-voltage characteristics and equivalent circuit 2.5.8. Solar cell efficiency 2.5.9. Limits of efficiency 2.5.10. Correct solar cell characterization 2.5.11. The \"O-Factor\" 3. Materials and experimental methods 3.1. Materials 3.2. Device fabrication and layout 3.2.1. Layer deposition 3.2.2. Encapsulation 3.2.3. Homogeneity of layer thickness on a wafer 3.2.4. Device layout 3.3. Characterization 3.3.1. Electrical characterization 3.3.2. Sample illumination 3.3.3. Temperature dependent characterization 3.3.4. UPS 4. Simulations 5.1. Design of single carrier devices 5.1.1. General design requirements 5.1.2. Single carrier devices for space-charge limited current 5.1.3. Ohmic regime 5.1.4. Design of injection and extraction layers 5.2. Advanced evaluation of SCLC – potential mapping 5.2.1. Potential mapping by thickness variation 5.2.2. Further evaluation of the transport profile 5.2.3. Injection into and extraction from single carrier devices 5.2.4. Majority carrier approximation 5.3. Proof of principle: POEM on simulated data 5.3.1. Constant mobility 5.3.2. Field dependent mobility 5.3.3. Field and charge density activated mobility 5.3.4. Conclusion 5.4. Application: Transport characterization in organic semiconductors 5.4.1. Hole transport in ZnPc:C60 5.4.2. Hole transport in ZnPc:C60 – temperature variation 5.4.3. Hole transport in ZnPc:C60 – blend ratio variation 5.4.4. Hole transport in ZnPc:C70 5.4.5. Hole transport in neat ZnPc 5.4.6. Hole transport in F4-ZnPc:C60 5.4.7. Hole transport in DCV-5T-Me33:C60 5.4.8. Electron transport in ZnPc:C60 5.4.9. Electron transport in neat Bis-HFl-NTCDI 5.5. Summary and discussion of the results 5.5.1. Phthalocyanine:C60 blends 5.5.2. DCV-5T-Me33:C60 5.5.3. Conclusion 6. Organic solar cell characteristics: the influence of temperature 6.1. ZnPc:C60 solar cells 6.1.1. Temperature variation 6.1.2. Illumination intensity variation 6.2. Voc in flat and bulk heterojunction organic solar cells 6.2.1. Qualitative difference in Voc(I, T) 6.2.2. Interpretation of Voc(I, T) 6.3. BHJ stoichiometry variation 6.3.1. Voc upon variation of stoichiometry and contact layer 6.3.2. V0 upon stoichiometry variation 6.3.3. Low donor content stoichiometry 6.3.4. Conclusion from stoichiometry variation 6.4. Transport material variation 6.4.1. HTM variation 6.4.2. ETM variation 6.5. Donor:acceptor material variation 6.5.1. Donor variation 6.5.2. Acceptor variation 6.6. Conclusion 7. Summary and outlook 7.1. Summary 7.2. Outlook A. Appendix A.1. Energy pay-back of this thesis A.2. Tables and registers