Ce travail a porté sur la synthèse et caractérisations structurales, optiques et électriques des films d’oxyde d'étain (SnOx) dopés avec des éléments de terres rares (RE: Néodyme, Praséodyme ou Ytterbium). L’objectif est de démontrer la conversion de photons UV voire Visible en photons rouges via ces films RE :SnOx, tout en conservant leurs propriétés d’oxydes transparents conducteurs. Les films ont été produits par des méthodes chimiques (sol-gel, précipitation) ou physiques (pulvérisation cathodique). Grâce à des analyses fines, nous avons pu corréler les propriétés structurales et de composition des couches RE :SnOx avec leurs propriétés d’émission de photons. Nous avons pu établir les conditions optimales de conversion photonique dans des systèmes à une seule ou double terre rare. Les mécanismes régissant le transfert dans ces films ont été avancés. Enfin, nous avons appliqué ces couches minces RE :SnOx optimisés sur des cellules solaires en silicium et en CIGS et nous avons montré une amélioration des paramètres photovoltaïques du dispositif ainsi qu’un net gain dans la réponse spectrale de la cellule dans l’UV. / Spectral conversion using lanthanide doped materials with excellent performances is a great challenging topic and of particular interest for photovoltaic. This work aims at functionalizing transparent conductive oxide materials with rare earth elements for photons conversion purpose without affecting transparency and transport properties of the TCO. The spectral conversion targeted in this thesis is of type “down”, in other words, we aim at converting high energy UV photons into low energy visible or NIR photons useful to solar cells. For this purpose we investigated the doping process of SnO2 as a host material with different rare earths such as Nd, Tb, Pr, and Yb. To understand the insertion process and the optical activation of the rare earth, RE-doped SnO2 nanoparticles (powders) have been synthesised by two chemical methods: co-precipitation and sol-gel. The results have shown an efficient insertion of the RE into the SnO2 structure with excellent emission properties. In view of application of RE-doped SnOx thin films to solar cells, studies concerning NIR emitting RE have been conducted (Nd, Yb, and co-doping with Yb and Nd) using sputtering. Several deposition parameters and post deposition treatments have been done in order to find the best chemical environment favourable to the RE emission. We have precisely identified the region of the UV light converted into NIR photons and proposed several energy transfer mechanisms occurring between the host SnOx and the REs. In case of co-doping, a second spectral conversion process has been identified; visible photons can be efficiently converted into NIR photons through energy transfer from Nd3+ to Yb3+ ions. Finally, application of these conversion layers to solar cells such as CIGS and Si based have shown an improvement of the cells characteristics, among others the Field factor, the cell efficiency and the increase of the spectral response of the cell in the UV region, thanks to the conversion of the UV photons into NIR photons. The good electrical properties of the RE-doped SnOx layers have been highlighted as well. We believe that these conversion layers will provide a step ahead towards better solar cells performances.

Made available in DSpace on 2015-03-03T15:11:25Z (GMT). No. of bitstreams: 1 JoseFernandoVN.pdf: 1709074 bytes, checksum: 0af621e6374e339196c6c65ecb0f15bc (MD5) Previous issue date: 2007-08-24 / O presente trabalho tem como objetivo investigar as caracter?sticas de filmes de SnO2 depositados em substrato de vidro borosilicato por um processo de silk-screen modificado para obten??o de espessura fina compat?vel com a aplica??o em c?lulas solares policristalinas de baixo custo. O filme de SnO2 ? um dos mais apropriados para obten??o de vidro TCO (transparent conductive oxide) para uso em c?lulas solares devido a sua baixa resistividade el?trica e alta transmit?ncia, sendo quimicamente inerte, mecanicamente duro e tem resist?ncia a altas temperaturas, o que facilita ent?o a calcina??o das amostras entre 500? C a 550? C. Os filmes foram obtidos a partir de uma solu??o precursora b?sica, preparada pela dissolu??o de SnCl2.2H2O em Etanol (99,5 %). Foi realizado um planejamento fatorial 2(3-1) para analisar a influ?ncia dos par?metros concentra??o da solu??o precursora (CETN), temperatura de calcina??o (TC) e taxa de aquecimento (tX) na calcina??o, sendo a concentra??o CETN o par?metro que apresentou maior efeito sobre os par?metros de respostas investigados: espessura do filme (?), resistividade de superf?cie (?) e a transmit?ncia relativa (?). Foi poss?vel obter com a metodologia utilizada, filmes com espessuras da ordem de 1 Nm com resistividade de superf?cie de 10 / e transmit?ncia relativa entre 70 e 80 %.

[pt] A gestão do processo de compras ganhou grande importância recentemente, tornando-se hoje um elemento essencial para as organizações empresarias. Essa gestão é um processo complexo e customizado, devido à enorme variedade de produtos e serviços comprados atualmente por uma organização. Portanto, essas empresas precisam de uma ferramenta para agrupar seus bens adquiridos de forma que se possa utilizar a mesma estratégia de compra para todos os grupos de itens com características similares. Neste sentido, muitas organizações vêm utilizando as matrizes de portfólio para ajudá-las a identificar não só o tipo de estratégia que deve ser adotada na aquisição de seus itens, mas também a profundidade da relação com o fornecedor desses itens (e.g. desenvolver ou não uma aliança estratégica). Apesar da crescente utilização dessas matrizes, a literatura ainda carece de ferramentas para ajudar as organizações a inserir seus produtos e serviços de compras em suas matrizes. Neste contexto, a presente dissertação tem como objetivo oferecer uma metodologia de elaboração de matrizes de portfólios que permita definir o que impacto no lucro e risco de suprimento (eixos da matriz) realmente significam e como uma organização pode mensurar essas dimensões. No intuito de verificar a viabilidade prática de sua aplicação, essa metodologia contou com uma ferramenta de apoio à decisão, o Processo de Análise Hierárquica – AHP, e com o Custo Total de Propriedade – TCO. A metodologia foi aplicada com sucesso em uma empresa de mídia ao longo do segundo semestre de 2008. / [en] Management of procurement process is now seen as an essential element to enterprise organizations. This management is a complex process, and customized due to the huge diversity of products and services that must be bought by any company. Therefore, each and every company needs some kind of tool to group its assets, in order to use the same procurement strategy for all groups of items sharing similar characteristics. Many companies have started to use portfolio matrix to help identifying not only the right procedure to purchase items, but also the right depth of the relationship with the people who are going to supply these items – e.g., developing the right strategy to supply or not these items through a strategic alliance. Despite the growing use of this matrix, literature still lacks tools to help organizations to insert their products and procurement services in their specific matrix. The present dissertation aims to offer a way of building a methodology able to elaborate a portfolio matrix that will disclose what profit impact and supply risk (matrix axes) really mean, and in which way any organization can evaluate these dimensions. In order to verify its practical viability, this methodology relies upon the Analytic Hierarchy Process - AHP and Total Cost of Ownership - TCO. This methodology was successfully applied on a media company along the second semester of 2008.

Le véhicule électrique est une des solutions de transport respectueuses de l’environnement, n’émettant pas de polluant lors de son utilisation. Gruau, constructeur carrossier pour véhicules utilitaires, se lance activement dans le transport écologique sur le segment de l’utilitaire 3,5t. Afin d’accroitre les ventes de véhicules utilitaires électriques, il est nécessaire d’en réduire le coût total de possession (ou TCO (Total Cost of Ownership)). L’objectif de cette thèse est d’étudier et de modéliser le comportement des composants de ce véhicule électrique pour simuler des calculs de TCO. Le composant principal étudié est la batterie, dont la durée de vie limitée conditionne la rentabilité du véhicule. La première partie des travaux fut consacrée à la modélisation du comportement du véhicule en fonction d’une mission client donnée. Une étude des cellules de batterie est réalisée dans le but de construire un modèle multi-physique complet en prenant en considération le vieillissement calendaire et le vieillissement en cyclage. Un modèle énergétique global, comprenant ce modèle batterie, permet de déterminer l’énergie nécessaire pour un parcours donné et de simuler le vieillissement des cellules électrochimiques afin de calculer le TCO. Une seconde partie est orientée vers le calcul du TCO. La mise en oeuvre d’un algorithme d’optimisation avec une méthodologie d’accélération des calculs a permis de réaliser les calculs dans des temps raisonnables (passage de 13h à 15min par itération). Après étude de l’impact du dimensionnement de la batterie sur le TCO, il en ressort que la réduction de la capacité n’entraine pas systématiquement la réduction du TCO. Il existe pour chaque mission un point de TCO optimal (jusqu’à 17% d’éconnomie). Afin d’améliorer le TCO, des stratégies de recharge intelligentes sont élaborées et permettent rentabilité accrue du VUE (jusqu’à 29%). Ce travail a été intégré dans un logiciel d’aide à la décision de la capacité de la batterie suivant les besoins du client, destiné aux forces de ventes commerciales. / The electric vehicle is one of the environmentally friendly transport solutions that emit no pollutant during its use. Gruau, manufacturer-converter for light commercial vehicles (LCV), is actively involved in green transport in the 3.5t segment. In order to increase sales of electric LCV, it is necessary to reduce its total cost of ownership (TCO). The objective of this thesis is to study and model the behavior of the components of this electric vehicle in order to simulate TCO. The main component studied is the battery, whose limited lifetime will determine the profitability of the vehicle. The first part of the work was devoted to modeling the behavior of the vehicle according to a given customer mission. The study of battery cells was done with the aim of building a complete multi-physics model taking into account calendar aging and cycling aging. Then, this battery model is integrated in a complete energy model taking into account all the components of the studied vehicle. Then a global model, including this battery model, makes it possible to determine the energy required for a given path and to simulate the aging of the electrochemical cells in order to calculate the TCO. A second part is oriented towards the calculation of the TCO. The implementation of an optimization algorithm, with a methodology of computing acceleration, allowed to achieve the computations in reasonable times (reduction from 13h to 15min by iteration). After studying the impact of battery sizing on the TCO, it appears that the reduction of the battery capacity does not systematically lead to the reduction of the TCO. There is therefore an optimum TCO point for each mission (up to 17% savings). In order to improve the TCO, smart recharging strategies are developed and allow increasing e-LCV profitability (up to 29%). This work is integrated into a decision support software relative to the battery capacity according to customer needs, intended for commercial sales forces.

Norway has already an almost emission-free power production and its sales of zero-emission light-duty vehicles surpassed 30% in 2018; a natural next challenge is to identify ways to reduce emissions of heavyduty vehicles. In this work the possibilities to deploy Fuel Cell Electric Trucks (FCET) on the route Oslo-Trondheim are analyzed by doing a techno-economic analysis. The literature study identified that in average 932 kton goods where transported between the cities. The preferred road choice goes through Østerdalen and that an average load for a long-distance truck is 16 tons. The methodology used in the study is based on cost curves for both truck and infrastructure, and a case study with various scenarios is evaluated to find a profitable business case for both an FCET fleet and its infrastructure. The cost curves for trucks are based on total cost of ownership (TCO) as a function of hydrogen price, while the levelized cost of hydrogen (LCOH) is used to present the cost of infrastructure. An analysis was made to identify the trucks component sizes and a FCET for this route would require an onboard hydrogen storage of 46 kg, a fuel cell stack with a nominal power of 200 kW, a battery of 100 kWh (min SOC 22%), and an electric motor with a rated power of 402 kW. TCO was calculated both for an FCET based on the dimensioned components and a biodiesel truck. The results show that an FCET purchased in 2020 can be competitive with biodiesel with a hydrogen price of 38.6 NOK/kgH2. While the hydrogen price can increase to 71.8 NOK/ kgH2 if the FCET is purchased in 2030. To identify the most suitable infrastructure, four different designs of hydrogen refueling stations (HRS) were compared. Furthermore, hydrogen production units (HPUs) with both alkaline or PEM type water electrolyzer were compared. The analysis in this study showed that the most cost competitive option was a 350-bar HRS without cooling, which only can serve type III onboard storage tanks. A HPU with alkaline electrolyzer was the most price competitive alternative. In case each HRS is refueling more than 7 FCETs per day, an HPU in direct connection to HRS is the preferred infrastructure setup. Three HRS are required along the route to ensure a minimum service level for the FCETs. When the TCO of the fuel cell truck and LCOH of the hydrogen infrastructure were compared for a 2020 scenario, no feasible solution was identified. The cost of installing three HRS in 2020, serving a fleet of 14-24 trucks, would cost 16.0 – 17.6 million NOK/year more than a fleet based on biodiesel trucks. In a future scenario, where both the FCET and infrastructure costs decrease due to expected learning curves, a business case can be found if at least 5 FCETs were refueling at each HRS on daily basis, which corresponds to a total fleet of approx. 24 FCETs. Finally, a set of clear recommendations on how to improve the techno-economic analysis in future studies are provided. Both by identifying areas lacking sufficient documentation and by providing steps how the tecno-economic model could be enhanced. / Norge har redan en nästintill utsläppsfri elproduktion och nollutsläppsbilar stod för mer än 30% av nybilsförsäljningen under år 2018. En naturlig nästa utmaning är att finna sätt att minska utsläpp från lastbilar. I detta examensarbete analyseras möjligheterna att introducera bränslecellslastbilar (FCET) efter dess engelska förkortning) på sträckan Oslo - Trondheim genom att göra en teknisk-ekonomisk bedömning. Litteraturstudien visade att i genomsnitt 932 kton gods fraktas mellan städerna, att vägen genom Østerdalen är att föredra och att genomsnittlig last för en långtradare är 16 ton. Arbetets metod bygger på att identifiera kostnadskurvor för både lastbilar och infrastruktur. Dessa kurvor kombineras i olika scenarier för att finna omständigheter där både en FCET-flotta och dess infrastruktur är lönsamma. Kostnadskurvorna för lastbilar baseras på den totala ägandekostnaden (TCO) efter dess engelska förkortning) som en funktion av vätgaspriset, medan den utjämnade kostnaden för vätgas (LCOH) efter dess engelska förkortning) används för att presentera kostnaden för infrastruktur. En analys gjordes för att finna passande storlek på FCET drivlina. För den specifika sträckan krävs en hydrogentank på 46 kg, en bränslecellstack med nominell effekt på 200 kW, ett batteri på 100 kWh (min SOC 22%) och en elmotor med nominell effekt på 402 kW. TCO beräknades både för en FCET baserat på de dimensionerade komponenterna och en lastbil som går på biodiesel. En FCET som köps 2020 blir konkurrenskraftig om vätgaspriset är 38,6 NOK/kgH2, medan vätgaspriset kan öka till 71,8 NOK/kgH2 om FCET köps 2030. Skillnaden är baserad på en framtida prisnedgång för FCET. För att finna den mest lämpliga lösningen på infrastruktur; analyserades fyra olika utformningar av vätgaspåfyllningsstationer (HRS). I tillägg jämfördes vätgasproduktionsenheter (HPU) baserat på antingen alkalisk eller PEM-typ av elektrolysator. Resultaten visade at en 350 bar HRS utan kylning, som endast kan fylla typ III lagringstankar, som det billigaste alternativet. Den alkaliska elektrolysatorn kunde producera vätgas för något lägre kostnad. Det billigaste alternativet för infrastruktur av de olika framtagna scenarios var att placera HPU bredvid HRS om minst 7 FCET tankar dagligen på varje station. Minst 3 HRS krävs längs rutten för att tillhandahålla en minsta servicenivå för FCET. När TCO för bränslecellslastbil och LCOH för infrastruktur jämfördes för ett 2020-scenario så fanns det ingen lönsam lösning. Kostnaden för att installera 3 HRS år 2020 som betjänar en lastbilflotta mellan 14-24 lastbilar skulle kosta 16,0 - 17,6 miljoner NOK/år mer än en lastbilsflotta som går på biodiesel. I ett framtida scenario där både FCET- och infrastrukturkostnaderna minskar på grund av större produktionsvolymer så kan vätgassatsning bli lönsam om minst 5 FCET tankar dagligen på varje HRS. Det motsvarar en lastbilsflotta på omkring 24 lastbilar för hela rutten. Till slut finns en rad klara rekommendationer om hur den tekno-ekonomiska analysen kan förbättras. Det upptäcktes både områden med otillräcklig dokumentation och summerades hur den teknoekonomiska modellen kan förbättras.

Les semi-conducteurs transparents de type oxyde, communément appelés TCO (Transparent Conducting Oxides) sont utilisés comme électrodes transparentes dans des nombreux d'applications telles que les cellules solaires, les écrans à cristaux liquides, les écrans tactiles et autres. Toutefois, les applications technologiques sont actuellement limitées puisque les TCO possédant des propriétés électriques et optiques satisfaisantes sont uniquement des semi-conducteurs de type n. Les oxydes de cuire de structures delafossite ACuO2 ou du type SrCu2O2, présentent des prometteuses avec un comportement de semi-conduction de type P et une faible absorption optique dans le spectre visible. Dans cette thèse, le systèm MOCVD (Dépôt chimique en phase vapeur du métal organique) a été utilisé pour le dépôt des couches minces de SrCu2O2. Cette phase est obtenue après quelques étapes de recuit sous oxygène puis argon, ou azote uniquement avec en particulier la nécessité de réalier des recuit rapaides. Les propriétés électriques et optiques mesurées pour la couche mince de SrCu2O2 ont un ordre de grandeur similaire à ce qui est publié dans la littérature.

Textured SnO2 films as TCO have been investigated to determine the effect of surface roughness on the performance of CdS/CdTe solar cells. Film roughness was controlled by varying the substrate temperature. Characterization of the SnO2 films has also carried out using AFM measurements. It was found that increase in substrate temperature results in increased roughness of the film. A series of cells were fabricated with different CdS thicknesses to determine the combined effect of SnO2 roughness and CdS thickness. As a part of fabrication process, cells were subjected to different post deposition treatments. It was observed that roughness seems to be critical when CdS remained in the final device is thin. The performance of CdS/CdTe devices fabricated was characterized using J-V and spectral response measurements. It was found that cells with initial CdS thickness of 1000 showed better performance than those with thicker CdS for the same roughness of SnO2. Conversion efficiency of 13.37% was achieved by increasing the SnO2 roughness and depositing thicker CdS initially.

Cadmium Zinc Telluride (CdxZn1-xTe or CZT) is a ternary semiconductor with a tunable bandgap of 1.44-2.26 eV. Solar cells with efficiencies of 20% or higher can be achieved by using a tandem solar cell structure which consists of a top cell and a bottom cell connected in series. In this kind of a structure, the light passes through the top cell first which has a wider bandgap to absorb light of shorter wavelengths and the remaining light passes through the bottom cell with a lower bandgap to absorb light of higher wavelengths. For a tandem cell structure, the ideal bandgap for the top and bottom cell is 1.7 eV and 1 eV respectively. Cadmium Zinc Telluride is a suitable candidate for the top cell and Copper Indium Gallium Diselenide (CIGS) with a bandgap of around 1 eV is a suitable candidate for the bottom cell. This work involves characterization and optimization of CZT solar cells by Close Spaced Sublimation (CSS). Cadmium Zinc Telluride is deposited by the co sublimation of Cadmium Telluride (CdTe) and Zinc Telluride (ZnTe) chunks. Cadmium Zinc Telluride solar cells were fabricated using Tin Oxide (SnO2), Zinc Oxide (ZnO) and Zinc Stannate (Zn2SnO4) films as substrates. The as-deposited CZT films were studied by XRD, EDS and SEM measurements. The devices were characterized by Current-Voltage (I-V) and Spectral Response measurements.

Les couches minces d'oxyde d'étain sont largement utilisées dans différents domaines d'applications comme les électrodes transparentes, les détecteurs de gaz, ou encore les catalyseurs. Il a été montré que la nanostructure des films permettait d'améliorer sensiblement les propriétés optiques et électriques des couches minces de semiconducteurs. L'objectif principal de ce travail de thèse est de synthétiser des films minces de SnO2, en contrôlant leur nanostructure et leur composition. Lors de la croissance de couches minces dans notre système de dépôt chimique en phase vapeur assisté par plasma (PECVD), des poudres nanométriques, polymérisées en phase plasma, peuvent s'incorporer dans le film. Les propriétés électriques du plasma sont grandement affectées par la croissance de ces poudres, et il est ainsi possible de suivre leur évolution par des mesures de la tension d'autopolarisation (VDC) de l'électrode de tension. Dans un premier temps, nous avons établi l'influence des paramètres du procédé sur l'évolution de la VDC, et relié ses variations à la granulométrie du film observé par microscopie électronique à balayage. Nous avons ensuite modifié les temps d'allumage et d'extinction du plasma, en faisant fonctionner notre générateur en mode pulsé. Nous avons ainsi pu discuter différentes hypothèses sur les mécanismes de formations des poudres dans un plasma argon/oxygène/tétraméthylétain. Un lien entre les conditions de modulation du plasma et la présence de nanocristallites incorporées au film d'oxyde d'étain a pu être établi.

<p>Bakgrund: Företag behöver i dagens samhälle robusta och pålitliga datasystem. För att bygga ett väl fungerande nätverk måste dessa baseras på bra operativ- systemprogramvara. Den fria programvaran, Linux, har stärkt konkurrensen på marknaden för operativsystem. Att konkurrensen hårdnat gör det intressant att undersöka ifall kostnaderna för anskaffning och användning skiljer sig åt mellan olika operativsystem.</p><p>Syfte: Syftet med detta arbete är att skapa en LCC-modell vilken skall appliceras på operativsystem i datanätverk. Vidare skall vi använda modellen till att jämföra totalkostnaden för att anskaffa och nyttja operativsystem i datanätverk under nätverkets livstid.</p><p>Genomförande: För att uppnå vårt syfte har vi genomfört personliga intervjuer med ekonomi- och dataansvariga på tio olika organisationer. Utifrån dessa intervjuer har vi tillsammans med litteraturstudier konstruerat en LCC-modell. Denna har vi sedan använt för att skapa en reviderad LCC-modell som vi ansatt för att jämföra totalkostnaden för att nyttja Linux respektive Windows NT i sitt nätverk.</p><p>Resultat: Resultatet är en LCC-modell som kan användas i en rad olika syften. Vår reviderade modell visade att ett renodlat Linuxsystem är ett billigare alternativän ett renodlat Windows NT-system. Behovet har dock visat sig vara viktigare än priset vid val av system. För att reducera kostnader är det viktigt att satsa på utbildning och kvalitet.</p>