In this dissertation, the electrical characteristics of generally used hydrogenated amorphous silicon (a-Si:H) TFTs in LCD and newly risen amorphous indium-gallium-zinc oxide (a-IGZO) TFTs were studied. For modern mobile display and large-size flat panel display application, the traditional thin-film transistor-liquid crystal display (TFT-LCD) technology confronts with a lot of challenges and problems. In general, flexible displays must exhibit some bending ability; however, bending applies mechanical strain to electronic circuits and affects device characteristics. Therefore, the electrical characteristics of a-Si:H TFTs fabricated on stainless steel foil substrates with uniaxial bending were investigated at different temperatures. Experimental results showed that the on-state current and threshold voltage degraded under outward bending. This is because outward bending will induce the increase of band tail states, affecting the transport mechanism at different temperatures. In addition, for practical operation, the electrical characteristics of a-Si:H TFTs under flat and bending situations after AC/DC stress at different temperatures were studied. It was found that high temperature and mechanical bending played important roles under AC stress. The dependence between the accumulated sum of bias rising and falling time and the threshold voltage shifts under AC stress was also observed. Because a-Si:H is a photosensitive material, the high intensity backlight illumination will degrade the performance of a-Si:H TFTs. Thus, the photo-leakage current of a-Si:H TFTs under illumination was investigated at different temperatures. Experimental results showed that a-Si:H TFTs exhibited a pool performance at lower temperatures. The indirect recombination rate and the parasitic resistance (Rp) are responsible for the different photo-leakage-current trends of a-Si:H TFTs under varied temperature operations. To investigate the photo-leakage current, the a-Si:H TFTs were exposed to ultraviolet (UV) light irradiation. It was found that the photo current of a-Si:H TFTs was reduced after UV light irradiation. The detail mechanisms on reducing/increasing photo-leakage current by UV light irradiation were discussed. Recently, the oxide-based semiconductor TFT, especially a-IGZO TFT, is considered as one of promising candidates for active matrix flat-panel display. However, the a-IGZO TFT exists significant electrical instability issue and manufacturing problems. As a consequence, we investigated the effect of hydrogen incorporation on a-IGZO TFTs to reduce interface states between active layer and insulator. Experimental results showed that the electrical characteristics of hydrogen-incorporated a-IGZO TFTs were improved. The threshold voltage shift (£GVth) in hysteresis loop is suppressed from 4 V to 2 V due to the hydrogen-induced passivation of the interface trap states. Finally, we reported the effect of ambient environment on a-IGZO TFT instability. As a-IGZO TFTs were stored in atmosphere environment for 40 days, the transfer characteristics accompanying strange hump were observed during bias-stress. The hump phenomenon is attributed to the absorption of H2O molecule. Additionally, the sufficient electric field is also necessary to cause this anomalous transfer characteristic.

With the digital systems moving towards higher frequencies, lower operating voltages and higher power, supplying the required current at the right voltage and at the right time to facilitate timely switching of the CMOS circuits becomes increasingly challenging. The board level power supply cannot meet these requirements directly due to the high inductance of the package interconnections. To overcome this problem, several thin film decoupling capacitors have to be placed on the IC or close to the IC in the package. Two approaches were pursued for high-k thin film decoupling capacitors. 1) Low cost sol-gel based thin film capacitors on organic board compatible Cu-foils 2) RF-sputtered thin film capacitors on silicon substrate for silicon compatible processes While sol-gel provides cost effective technology, sputtered ferroelectric devices are more compatible from manufacturing stand point with the existing technology. Nano-crystalline barium titanate and barium strontium titanate film capacitor devices were fabricated and characterized for organic and silicon substrates respectively. Sol-gel barium titanate films were fabricated first on a bare Cu-foil and then transferred to organic board through a standard lamination process. With process optimization and film doping, a capacitance density of 3 µF/cm2 was demonstrated with breakdown voltage greater than 12V. Leakage current characteristics, breakdown voltages, and electrical reliability of the devices were significantly improved through doping of the barium titanate films and modified film chemistry. Films and interfaces were characterized with high resolution electron microscopy, SEM, XRD, and DC leakage measurements. RF sputtering was selected for ferroelectric thin film integration on silicon substrate. Barium strontium titanate (BST) films were deposited on various electrodes sputtered on silicon substrates. The main focus was to improve interface stabilities for high-k thin films on Si to yield large-area defect-free devices. Effect of bottom electrode selection and barrier layers on device yield and performance were investigated carefully. High yield and high device performance was observed for certain electrode and barrier layer combination. A capacitance density up to 1 µF/cm2 was demonstrated with a breakdown voltage above 15 V on large area, 7 mm2, devices. These two techniques can potentially meet mid-high frequency future decoupling requirements.

Η παρακολούθηση του ρεύματος διαρροής, και ειδικά της κυματομορφής του, είναι μια ευρύτατα διαδεδομένη τεχνική για την παρακολούθηση της επιφανειακής δραστηριότητας και κατάστασης των μονωτήρων υψηλής τάσης. Η παρακολούθηση στο πεδίο είναι απαραίτητη για να υπάρξει μια πιστή καταγραφή της δραστηριότητας και συμπεριφοράς σε πραγματικές συνθήκες, παρουσιάζει όμως σημαντικές δυσκολίες. Το πρόβλημα συνήθως παρακάμπτεται με την καταγραφή και μελέτη εξαγόμενων μεγεθών όπως η τιμή κορυφής και το φορτίο, μία προσέγγιση που οδηγεί όμως σε αμφίβολα αποτελέσματα. Η παρούσα διατριβή επικεντρώνεται στην διερεύνηση και ταξινόμηση κυματομορφών ρεύματος διαρροής καταγεγραμμένων στο πεδίο. Αρχικά, παρατίθεται μια λεπτομερής ανασκόπηση της καταγραφής και ανάλυσης ρεύματος διαρροής σε εργαστηριακές και πραγματικές συνθήκες. Στην συνέχεια, περιγράφεται το πεδίο μετρήσεων, δύο Υποσταθμοί Υψηλής Τάσης 150kV, το αναπτυχθέν λογισμικό αλλά και ο Υπαίθριος Σταθμός Δοκιμών όπου πρόκειται να αξιοποιηθούν τα αποτελέσματα. Μελετώνται περισσότερες από 100.000 κυματομορφές, που έχουν καταγραφεί σε μια περίοδο που ξεπερνάει τα δέκα έτη. Εξετάζεται και αξιολογείται το πρόβλημα του θορύβου και ταυτοποιούνται τρεις διαφορετικοί τύποι θορύβου. Εξετάζεται η επίδρασή τους στο πρόβλημα συσσώρευσης δεδομένων αλλά και στην ποιότητα της εξαγόμενης πληροφορίας. Για την αντιμετώπιση του προβλήματος εφαρμόζονται και αξιολογούνται τρεις διαφορετικές τεχνικές. Για την περαιτέρω ταξινόμησή των κυματομορφών που απεικονίζουν δραστηριότητα, χρησιμοποιούνται διάφορες τεχνικές επεξεργασίας σήματος, εξαγωγής και επιλογής χαρακτηριστικών καθώς και αναγνώρισης προτύπων όπως η Wavelet Multi-Resolution Ανάλυση, η Ανάλυση Fourier, τα Νευρωνικά Δίκτυα, το t-test, ο αλγόριθμος mRMR, ο αλγόριθμος κ-πλησιέστερων γειτόνων, ο απλός Μπεϋζιανός ταξινομητής και οι Μηχανές Διανυσμάτων Υποστήριξης. Συγκεντρωτικά, δίνεται μια συνολική εικόνα των διαφορετικών ζητημάτων που σχετίζονται με την παρακολούθηση του ρεύματος διαρροής. Παρατίθεται μια πλήρης εικόνα των κυματομορφών όπως αυτές καταγράφονται σε πραγματικές συνθήκες, υπογραμμίζοντας ιδιαιτερότητες που σχετίζονται με την φύση της εφαρμογής. Εφαρμόζονται και αξιολογούνται νέες προσεγγίσεις για την ταξινόμηση των κυματομορφών. Τα συνολικά αποτελέσματα προσφέρουν σημαντική ενίσχυση στην αποτελεσματικότητα της τεχνικής της παρακολούθησης του ρεύματος διαρροής, συμβάλλοντας σημαντικά στην μελέτη της επιφανειακής δραστηριότητας και συμπεριφοράς των μονωτήρων υψηλής τάσης. / Leakage current monitoring is a widely applied technique for monitoring surface activity and condition of high voltage insulators. Field monitoring is necessary to acquire an exact image of activity and performance in the field. However, recording, managing and interpreting leakage current waveforms, the shape of which is correlated to surface activity, is a major task. The problem is commonly by-passed with the extraction, recording and investigation of values related to peak and charge, an approach reported to produce questionable results. The present thesis focuses on the investigation and classification of field leakage current waveforms. At first, a detailed background of measuring and analyzing leakage current both in lab and field conditions is provided. Then, the monitoring sites, two 150kV Substations, as well as the developed custom-made software and the newly constructed High Voltage Test Station where the results of this thesis are to be implemented, is briefly described. More than 100.000 waveforms are investigated, recorded through a period exceeding ten years. Field related noise is thoroughly described and evaluated. Three different types of noise are identified and their impact on the size of accumulated data and on data interpretation is investigated. Three different techniques to overcome the problem are applied and evaluated. Activity portraying waveforms are further investigated. Further classification of activity portraying waveforms is performed employing signal processing, feature extraction and selection algorithms as well as pattern recognition techniques such as Wavelet Multi-Resolution Analysis, Fourier Analysis, Neural Networks (NNs), student’s t-test, minimum Redundancy Maximum Relevance (mRMR), k-Nearest Neighbors (kNN), Naive Bayesian Classifier and Support Vector Machines (SVMs). Overall results provide a full image of the various aspects of field leakage current monitoring. A detailed image of field waveforms, revealing several new attributes, is documented. New approaches for the classification of leakage current waveforms are introduced, applied on field waveforms and evaluated. Results described in this thesis significantly enhance the effectiveness of the leakage current monitoring technique, providing a powerful tool for the investigation of surface activity and performance of high voltage insulators.

Les élastomères diélectriques sont de plus en plus utilisés pour la réalisation des transducteurs dans de nombreux domaines industriels : interface haptique, robotique, biomimétisme, conversion d’énergie. Pour le fonctionnement de toutes ces applications, le polymère électroactif est soumis à une haute tension (de 1 à 10kV). Toutefois, le courant de fuite diminue l’efficacité et la durée de vie des dispositifs utilisant ces matériaux.Par ailleurs, une précontrainte mécanique (étirement) est généralement appliquée au polymère pour accroître l’efficacité énergétique dans la conversion mécanique-électrique. Les courants de fuite (et donc le champ de claquage du polymère) seront ainsi conditionnés par cette précontrainte et ce point doit faire l’objet d’une étude détaillée.L’objet de ce travail de thèse est de mener des analyses de courant de fuite sur des polymères électroactifs (élastomères polyacrylates du commerce VHB4910 et silicones Sylgard 186) non contraints et contraints mécaniquement pour évaluer l’amélioration ou la dégradation des performances électriques lorsqu’ils seront plus tard intégrés en géométrie électrode-polymère-électrode dans des transducteurs.Tout d’abord, nous avons mené une étude exhaustive sur l’influence des facteurs externes (étirement, température, champ électrique, nature de l’électrode) sur les propriétés électriques du polyacrylate VHB4910. Les études ont été réalisés sur des durées de polarisation courtes (quelques minutes) et longues (jusqu’à 15 heures). Au cours de ce travail, nous sommes également intéressés à l’étude du phénomène d’autocicatrisation sur le sylgard 186. Les tests ont été conduits pour différents types d’électrodes (or, aluminium, graphène, nanoplaquettes de graphène : GnP) déposées sur la surface de silicone. Une analyse par microscopie optique de la zone évaporée a été menée.La finalité de ces travaux aura permis d’optimiser des structures de récupération d’énergie électrostatique à base de polymères électroactifs. / Electroactive polymers known as dielectric elastomers have shown considerable promise for transducers. They are attractive for a wide range of innovative applications including softs robots, adaptive optics, haptic interface or biomedical actuation thanks to their high energy density and good efficiency. For the functioning of all these application, the electroactive polymer is subjected to high electrical field. Nevertheless, the performances of these transducers are affected by the losses and especially the ones induced by the leakage current.Mechanical pre-stretch is an effective method to improve actuation when a voltage is applied to the device made up of a dielectric elastomer sandwiched between two compliant electrodes. The overall performances of the structure (electromechanical conversion, efficiency, strain induced…) depend strongly on the electric and mechanical properties of the elastomer. Regarding electric characteristics, dielectric permittivity, dissipation factor and electric breakdown field have been deeply investigated according to various parameters such as frequency, temperature, pre-stretch, or nature of the electrodes but complete analysis of the leakage current is missing in the scientific literature.Thus, this work reports an extensive investigation on the stability of the current-time characteristics in dielectric elastomer. Particularly, we focus on the influence of the nature of the electrodes and pre-stress applied to the transducer. In order to evaluate the influence of the time duration on the behavior of the leakage current, short and long-term electrical stress times was applied during short times and up to 15 hours.Leakage current in electroactive polymers were discussed for a commercial polyacrylate (VHB4910 from 3M) currently used for soft transducers applications. This current is investigated as a function of external factors (stretching, temperature, type of material for electrodes)In order to evaluate the limitations in term of voltage and in the goal to increase the lifetime of these transducers, the second part of our study is focused on the dielectric strength of silicone rubbers for various types of electrodes (gold, Aluminum, graphene nanoplatelets, graphene : GnP). The effect of self-healing is particularly studied and a selection of electrodes for soft transducers based on dielectric elastomers is proposed.

Avec la miniaturisation des circuits intégrés, le délai de transmission dû aux interconnexions a fortement augmenté. Pour limiter cet effet parasite, le SiO2 intégré en tant qu'isolant entre les lignes métalliques a été remplacé par des matériaux diélectriques à plus faible permittivité diélectrique dits Low-κ. La principale approche pour élaborer ces matériaux est de diminuer la densité en incorporant de la porosité dans des matériaux à base de SiOCH. L'introduction de ces matériaux peu denses a cependant diminué la fiabilité : sous tension, le diélectrique SiOCH poreux est traversé par des courants de fuite et peut claquer, générant des défaillances dans le circuit. La problématique pour l'industriel est de comprendre les mécanismes de dégradation du diélectrique Low-κ afin de déterminer sa durée de vie aux conditions de température et de tension de fonctionnement. Dans ce contexte, les travaux de cette thèse ont consisté à étudier les mécanismes de conduction liés aux courant de fuite afin d'extraire des paramètres quantitatifs représentatifs de l'intégrité électrique du matériau. Nous avons utilisé ces paramètres afin de suivre le vieillissement du matériau soumis à une contrainte électrique. Nous avons également introduit la spectroscopie d'impédance à basse fréquence comme moyen de caractérisation du diélectrique Low-κ. Cet outil nous a permis de caractériser le diélectrique intermétallique de façon non agressive et d'identifier des phénomènes de transport de charges et de diffusion métallique à très basses tensions qui offrent des perspectives pour l'étude de la fiabilité diélectrique des interconnexions. / With the miniaturization of integrated circuits, transmission delay due to interconnects is hardly increased. To minimize this parasitic effect, low-κ dielectric materials are requested to replace SiO2 as inter-metal dielectric between metallic lines. With its low density, porous SiOCH are good candidate for such applications. However, the implementation of these materials decreased reliability: under voltage, leakage currents establish through low-κ dielectric whose breakdown can generate failures in circuits. The problem for manufacturers is to understand the degradation mechanisms of porous SiOCH to determine its lifetime at conditions of nominal temperature and voltage. In this frame, conduction mechanisms of leakage currents have been studied during this thesis to extract quantitative parameters that represent the electrical integrity of the dielectric. We have used these parameters to monitor the electrical aging of the dielectric under electrical stress. We have proposed low-frequency impedance spectroscopy as characterization tool of low-κ. This tool allowed to characterize the intermetal dielectric non-destructively and to identify phenomenon of carriers transport and metallic diffusion at very low voltages that open perspectives for the study of dielectric reliability in interconnects.

Ces travaux de thèse consistent à proposer des outils matériels et logiciels pour estimer et améliorer le rendement énergétique de la chaine de conversion d’énergie photovoltaïque pour les applications de l’habitat. Nous avons dans un premier temps proposé une nouvelle architecture mixte d’onduleur à 5 niveaux. Ce type de structure, fondé sur un couplage d’un onduleur en pont complet et d’une architecture NPC, permet de diminuer le THD de la tension de sortie du convertisseur tout en limitant les niveaux de courant de fuite induits par les modules photovoltaïques. Ce type d’architecture est constitué d’un nombre limité de dispositifs à semi-conducteurs par rapport à une structure NPC et permet d’améliorer la robustesse de l’onduleur. Ces premiers résultats de test à puissances réduite permettent de valider le concept proposé. On s’intéresse ensuite à l’étude des paramètres environnant du système pouvant impacter la production d’énergie. Il est mis en évidence l’influence de la variation du coefficient d’échange convectif avec la vitesse du vent. Pour cela, un outil flexible d’estimation de production a été développé. Il est alors possible de quantifier et de qualifier l’impact des conditions météorologiques sur la production d’énergie photovoltaïque. / This study deals with the development of hardware and software tools to estimate and improve the efficiency of the PV energy conversion chain for household photovoltaic applications. We firstly proposed a new mixed 5-level inverter. This type of structure, based on the mixture of a full bridge inverter and NPC architecture, reduces the converter output voltage THD while reducing levels of leakage current induced by the PV modules. This architecture consists of a limited number of semiconductor devices with respect to a NPC structure and improves the robustness of the inverter. Several test results in reduced power validate the concept proposed. Finally, we focus on some parameters that could perturb the system and impact the energy production. It is highlighted that the impact of the convective heat transfer coefficient variation with wind speed is important. For this purpose, a flexible tool was developed to estimate the PV production. It is then possible to quantify and qualify the impact of wind speed on the photovoltaic energy production.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis presents the development of a grid-connected transformerless three-phase photovoltaic inverter. The Neutral Point Clamped (NPC) three-level inverter was chosen for implementation. The grid connection is made with a modified LCL filter (MLCL), where the common point of the output filter capacitors is connected directly to the dc bus central point (neutral point). The MLCL filter reduces the leakage current of photovoltaic system and attenuates the current harmonics injected in the grid. A passive damping of MLCL filter resonance peak was employed in order to avoid instability in the grid connection. In this sense, this Master Thesis contributes proposing a passive damping design method which is based not only on the stability requirement, but also considers the leakage current of photovoltaic system, once that passive damping impacts on the high frequency components of voltage on parasitic capacitance. Therefore, based on leakage current limit and current loop stability, a range for the damping resistance was obtained. The control system of the threephase inverter was developed in a synchronous reference frame (dq0), where the proper alignment with the grid voltage reference vector allows the independent control of active and reactive power inject in the grid. Simulation and experimental results are shown to evaluate the inverter performance and to validate the theoretical analysis. / Esta Dissertação de Mestrado apresenta o desenvolvimento de um inversor fotovoltaico trifásico não isolado conectado à rede. A topologia desenvolvida foi a de um inversor trifásico três níveis com ponto neutro grampeado (NPC Neutral Point Clamped). A conexão com a rede é feita através de um filtro LCL modificado (LCLM), que possui o ponto comum dos seus capacitores conectado ao ponto central do barramento CC do inversor. O filtro LCLM possui a finalidade de reduzir a corrente de fuga do sistema fotovoltaico ao mesmo tempo em que atenua os harmônicos de corrente injetados na rede. De modo a evitar problemas de instabilidade da malha de corrente do inversor, um sistema de amortecimento passivo do pico de ressonância do filtro LCLM foi empregado. Neste sentido, esta Dissertação de Mestrado contribui propondo um método de projeto do amortecimento passivo que se baseia não somente no critério de estabilidade, mas que também considera a corrente de fuga do sistema fotovoltaico, uma vez que o amortecimento impacta na atenuação das componentes de alta frequência da tensão sobre a capacitância parasita dos módulos fotovoltaicos. Com isso, uma faixa de valores para a resistência de amortecimento foi obtida a partir do limite permitido para a corrente de fuga e da estabilidade da malha de corrente. O sistema de controle do inversor trifásico foi desenvolvido com base no sistema de coordenadas síncronas dq0, cujo correto alinhamento com o vetor de referência das tensões da rede permite o controle independente das potências ativa e reativa injetadas na rede. Resultados experimentais e de simulação são apresentados de modo a comprovar o desempenho do inversor trifásico.

Avec la miniaturisation continue des circuits intégrés et le remplacement de l’oxydede silicium par des diélectriques low-κ poreux à base de SiOCH, la fiabilité des circuitsmicroélectroniques a été fortement compromise. Il est aujourd’hui extrêmement importantde mieux appréhender les mécanismes de dégradation au sein de ces matériaux afin deréaliser une estimation précise de leur durée de vie.Dans ce contexte, ces travaux de thèse ont consisté à étudier les mécanismes de dégradationau sein du diélectrique afin de proposer un modèle de durée de vie plus pertinent.Par une étude statistique du temps à la défaillance sous différents types de stress électrique,un mécanisme de génération des défauts par impact est mis en évidence. En l’associantau mécanisme de conduction au sein du diélectrique, il a été possible de développer unmodèle de durée de vie cohérent pour les interconnexions permettant une estimation de ladurée de vie plus fiable que les modèles de la littérature. L’impact du piégeage de chargesdans le diélectrique a ensuite été analysé grâce à ce modèle. / With the constant size reduction of integrated circuits and the replacement of silicon dioxide with porous SiOCH, the reliability of interconnects has been sharply reduced. A better understanding of degradation mechanisms is now required in order to have a precise estimation of product lifetime. In this work, degradation mechanisms have been studied in order to propose a more accurate lifetime model. A statistical study of times to failure under various electrical stresses is used to explain the physical mechanisms involved in defect creation. Combining these degradation mechanisms and Poole-Frenkel conduction mechanism enables the use of a new lifetime model. This model leads to a better estimation of the lifetime than existing models. Finally, the effects of charge trapping on lifetime in these materials have been studied.

Les concepts de matériaux multiferroïques et/ou magnétoélectriques permettent d’envisager de nouveaux dispositifs de mémoires plus performants et moins consommateurs d’énergie. Malheureusement de tels matériaux présentant ces propriétés à température ambiante ne sont pour l’instant pas disponibles. Les matériaux qui font l’objet des études présentées dans ce manuscrit, les ferrites de gallium Ga2-xFexO3, 0,7 ≤ x ≤ 1,4, sont d’excellents candidats. Le présent travail de thèse en a étudié les propriétés électriques, tant sur matériaux massifs que couches minces. Nous avons mesuré une polarisation sur composés massifs du même ordre de grandeur que celle précédemment déterminée par calculs ab initio. Une considérable réduction des courants de fuite habituellement observés en couches minces a été possible grâce à la substitution de Fe2+ par Mg2+. Une polarisation réversible et un effet magnétoélectrique ont alors pu être mis en évidence. Compte tenu du caractère ferrimagnétique à température ambiante des couches minces considérées, ceci constitue la première manifestation d’un matériau multiferroïque et magnétoélectrique à réel intérêt applicatif. / Concepts of multiferroic and magnetoelectric materials allow designing new memory devices with better performances and less energy consumption. Unfortunately, such materials with room temperature applicability are not yet available.The material concerned by this study, gallium ferrites Ga2-xFexO3, 0.7 ≤ x ≤ 1.4, are excellent candidates for such applications. This work aimed at studying the electrical properties of the bulk material, as well as in thin films. We have measured a polarization on the bulk samples comparable to the value estimated by first principle calculations. A considerable reduction of the leakage currents usually observed in oxide thin films has been achieved by the doping by substitution of Fe2+ in the structure, using Mg2+. A switchable polarization and a magnetoelectric effect at room temperature in thin films have been observed. Considering the room temperature ferrimagnetic behavior of this compound, this is the first manifestation of a multiferroic and magnetoelectric with real potential and technological applications.

Dans le but de l’intégration des supercondensateurs dans des applicationstransport, la connaissance et l’étude de leur comportement au cours du vieillissementest nécessaire. L’objectif de cette thèse est donc la compréhension et lamodélisation des phénomènes de vieillissement observés sur lessupercondensateurs. Pour cela, des méthodologies de caractérisation électriques etdes protocoles expérimentaux originaux combinant les différentes contraintes devieillissement ont été mis en oeuvre. Des mesures du courant de fuite et des tests devieillissement combinés ont été effectués. Les résultats obtenus sont présentés. Ilsont ainsi servis au développement et l’implémentation de modèles permettant le suivide l’évolution des performances des supercondensateurs avec le vieillissement. / The study of the behavior of supercapacitors during ageing is required in orderto integrate them in transportation applications. The aim of this thesis is tounderstand and model ageing phenomena observed on supercapacitors. For thispurpose, electrical characterization methodologies and original experimentalprotocols combining various constraints of ageing have been implemented.Measurements of leakage current and combined ageing tests were conducted. Theobtained results were used for developing models allowing the monitoring of theevolution of supercapacitors performance during ageing.