Academic literature on the topic 'Cu based cells'

ABSTRACTMoO3 films with a high work function (5.5 eV), high transparency, and a wide bandgap (3.0 - 3.4 eV) are a potential candidate for the primary back contact of Cu(InGa)Se2 thin film solar cells. This may be advantageous to form ohmic contact in superstrate devices where the back contact will be deposited after the Cu(InGa)Se2 layer and MoSe2 layer doesn’t form during Cu(InGa)Se2 deposition. In addition, the MoO3 may be incorporated in a transparent back contact in tandem or bifacial cells. In this study, MoO3 films for use as a back contact for Cu(In,Ga)Se2 thin film solar cells were prepared by reactive rf sputtering with O2/(O2+Ar) = 35%. The effect of post processing on the structural properties of the deposited films were investigated using x-ray diffraction and scanning electron microscopy. Annealing resulted in crystallization of the films to the α-MoO3 phases at 400°C. Increasing the oxygen partial pressure had no significant effect on optical transmittance of the films, and bandgaps in the range of 2.6-2.9 eV and 3.1-3.4 eV were obtained for the as deposited and annealed films, respectively. Cu(In,Ga)Se2 thin film solar cells prepared using an as-deposited Mo-MoO3 back contact yielded an efficiency of >14% with VOC = 647 (mV), JSC = 28.4 (mA), and FF. = 78.1%. Cells with ITO-MoO3 back contact showed an efficiency of ∼12% with VOC = 642 (mV), JSC = 26.8 (mA), and FF. = 69.2%. The efficiency of cells with an annealed MoO3 back contact was limited to 4%, showing a blocking diode behavior in the forward bias J-V curve. This may be caused by the presence of a barrier between the valence bands of the Cu(In,Ga)Se2 and MoO3, due to the higher bandgap of the annealed MoO3 films. SEM cross section studies showed uniform coverage of the as-deposited MoO3 layer and formation of voids for the annealed MoO3 film. Structural orientation of the Cu(In,Ga)Se2 absorber layer was also altered by the MoO3 film and less-oriented films were observed for either cases.

AbstractIn this manuscript, we give an overview of the main insights into our growth procedure for kesterite solar cells and show the possibilities that are provided by this approach. The importance of using Cu–Sn alloy instead of elemental Sn and Cu in the precursor is shown. We discuss how the alloy approach stabilises the composition and helps guide the process along a preferred reaction pathway. A summary of our previously reported findings in the context of our latest results on kesterite solar cells prepared from Cu–Sn alloyed precursors is drawn. The positive impact of an alloy precursor configuration on the formation pathway, process control, and process resilience is demonstrated. Furthermore, a new optimisation strategy for kesterite, based on the reported pathway, is discussed, including a smooth phase transition from Cu-rich to Cu-poor kesterite. Finally, we demonstrate results on buffer optimisation and the application of a promising hybrid buffer configuration of CdS/Zn(O,S), which can reduce the optical losses in the solar cell structure.

Constructed on the benzothiazole-oxanthracene structure, a fluorescent probe RBg for Cu+ was designed under the ESIPT mechanism and synthesized by incorporating amide bonds as the connecting group and glyoxal as the identifying group. Optical properties revealed a good sensitivity and a good linear relationship of the probe RBg with Cu+ in the concentration range of [Cu+] = 0–5.0 μmol L−1. Ion competition and fluorescence-pH/time stability experiments offered further possibilities for dynamic Cu+ detection in an aqueous environment. HRMS analysis revealed a possible 1:1 combination of RBg and Cu+. In addition, colorimetric Cu+ detection and lysosome-targeted properties of the probe RBg were analyzed through RBg-doped PVDF nanofiber/test strips and RBg-Mito/Lyso trackers that were co-stained in living HeLa cells, enabling the probe’s future applications as real-time detection methods for dynamic Cu+ tracking in the lysosomes and Cu+ detection under diversified conditions.

Given the high percentage of metal cost in cell processing and concerns due to increasing Ag prices, alternative metallization schemes are being considered. Ni-Cu based front side metallization offers potential advantages of finer grid lines, lower series resistance, and reduced costs. A brief overview of various front side patterning techniques is presented. Subsequently, working principle of various plating techniques is discussed. For electroless plated Ni seed layer, fill factor values nearing 80% and efficiencies close to 17.5% have been demonstrated, while for Light Induced Plating deposited layers, an efficiency of 19.2% has been reported. Various methods for qualifying adhesion and long term stability of metal stack are discussed. Adhesion strengths in the range of 1–2.7 N/mm have been obtained for Ni-Cu contacts tabbed with conventional soldering process. Given the significance of metallization properties, different methods for characterization are outlined. The problem of background plating for Ni-Cu based metallization along with the various methods for characterization is summarized. An economic evaluation of front side metallization indicates process cost saving of more than 50% with Ni-Cu-Sn based layers. Recent successful commercialization and demonstration of Ni-Cu based metallization on industrial scale indicate a potential major role of Ni-Cu based contacts in near future.

Membrane trafficking pathways emanating from the Golgi regulate a wide range of cellular processes. One of these is the maintenance of copper (Cu) homeostasis operated by the Golgi-localized Cu-transporting ATPases ATP7A and ATP7B. At the Golgi, these proteins supply Cu to newly synthesized enzymes which use this metal as a cofactor to catalyze a number of vitally important biochemical reactions. However, in response to elevated Cu, the Golgi exports ATP7A/B to post-Golgi sites where they promote sequestration and efflux of excess Cu to limit its potential toxicity. Growing tumors actively consume Cu and employ ATP7A/B to regulate the availability of this metal for oncogenic enzymes such as LOX and LOX-like proteins, which confer higher invasiveness to malignant cells. Furthermore, ATP7A/B activity and trafficking allow tumor cells to detoxify platinum (Pt)-based drugs (like cisplatin), which are used for the chemotherapy of different solid tumors. Despite these noted activities of ATP7A/B that favor oncogenic processes, the mechanisms that regulate the expression and trafficking of Cu ATPases in malignant cells are far from being completely understood. This review summarizes current data on the role of ATP7A/B in the regulation of Cu and Pt metabolism in malignant cells and outlines questions and challenges that should be addressed to understand how ATP7A and ATP7B trafficking mechanisms might be targeted to counteract tumor development.

Thin film solar cell technologies are rapidly developing, and chalcopyrite (Cu(In,Ga)Se2) based devices have demonstrated the highest power conversion efficiencies on the laboratory scale. However, in spite of this promise, there are concerns about the mid- to long-term viability of the material because it contains the relatively scarce elements of indium and gallium. This has led to the development of kesterite (Cu2ZnSn(S,Se)4) based photovoltaic technologies, which is particularly promising because of its similarities with the chalcopyrite material. In this material system indium and gallium are replaced by the more earth abundant elements of zinc and tin. Device efficiencies are still lower than Cu(In,Ga)Se2, but further research and development has led to significant increases in performance in the past few years. To date the device structure and processing parameters for kesterite based devices has been mostly copied from chalcopyrite based technologies. The objective of this thesis is to further develop these kesterite based technologies, and it covers some of the basic challenges related to it, including secondary phase formation and identification, and optimization of the front and back contact areas. Particular emphasis is placed on the deposition and thermal processing of this compound, and how these affect secondary phase formation and device properties. It is based on several articles which explore these in depth. This includes detailed characterization by Raman scattering spectroscopy, x-ray diffraction, scanning electron microscopy, and other techniques. Highlights of the thesis work include: development of a selective chemical etch to remove ZnS, a common secondary phase in this system, which leads to significant improvements in device performance; elaboration of a sulfo-selenization method to form Cu2ZnSn(S,Se)4 from metallic precursors; and understanding the influence of thermal processing parameters on phase formation and distribution
En los últimos años ha habido un rápido desarrollo en las tecnologías de celdas solares basadas en capa delgada, siendo hasta el momento los dispositivos basados en calcopiritas (Cu(In,Ga)Se2) los que han mostrado una mayor eficiencia de conversión fotovoltaica a escala de laboratorio. Sin embargo, y a pesar de tan prometedores resultados, existe una preocupación sobre la viabilidad a medio y largo término de estos materiales debido a la presencia en su composición de elementos relativamente escasos en la corteza terrestre, como son el In y el Ga. Esto ha llevado al desarrollo de tecnologías fotovoltaicas basadas en kesterita (Cu2ZnSn(S,Se)4), que es especialmente prometedora dada su gran similitud con la calcopirita. En este compuesto, el indio y el galio son reemplazados por elementos más abundantes como son el cinc y el estaño. Los valores de eficiencia de los dispositivos aún están por debajo de los del Cu(In,Ga)Se2, pero nuevas investigaciones y técnicas de desarrollo han llevado a importantes avances en los últimos años. A día de hoy, tanto los parámetros de fabricación como la estructura de los dispositivos basados en kesterita han seguido un camino prácticamente idéntico al de las tecnologías basadas en calcopiritas. El objetivo de esta tesis es el de profundizar en el desarrollo de las tecnologías basadas en kesterita, lo que cubre algunos de los retos básicos relacionados con ellas, como son la formación e identificación de fases secundarias o la optimización de las áreas de contacto frontal y posterior. Se ha puesto especial énfasis en la deposición y los procesos térmicos implicados en el crecimiento de este compuesto, y en ver cómo afectan a la posible formación de las fases secundarias y las propiedades del dispositivo. La tesis en sí está estructurada a partir de los diversos estudios publicados en revistas científicas. Dichos estudios incluyen una caracterización detallada por espectroscopia de dispersión Raman, difracción de rayos X, microscopia electrónica de barrido, y otras técnicas. Los puntos principales de este trabajo son: el desarrollo de un ataque químico selectivo para la eliminación del ZnS (una fase secundaria comúnmente presente en este sistema), con la consecuente mejora de las características del dispositivo; la elaboración de un método de sulfo-selenización para la formación de Cu2ZnSn(S,Se)4 a partir de precursores metálicos; y la resolución de cómo influyen los parámetros de los diferentes procesos térmicos en la formación y distribución de las fases.

Réduire l’épaisseur de l’absorbeur des dispositifs photovoltaïques à base de couches minces est une voie prometteuse pour améliorer leur compétitivité industrielle, via une économie de matières premières et une cadence de production plus élevée. Cela peut aussi accroître leur efficacité en diminuant le parcours des porteurs de charge photogénérés. Cependant, l’efficacité des cellules solaires à base de Cu(In,Ga)Se ₂ (CIGS) ultramince avec une épaisseur d’absorbeur d’environ 500 nm, soit environ 5 fois inférieure aux cellules conventionnelles, est limitée par deux phénomènes : les recombinaisons non-radiatives de charges au contact arrière et l’absorption incomplète de la lumière solaire incidente. Différentes stratégies ont été étudiées afin de limiter ces pertes. Dans un premier temps, la composition des couches ultraminces de CIGS a été optimisée pour y créer un gradient du minimum de la bande de conduction. Le champ électrique résultant permet de faciliter la séparation des charges et de limiter les recombinaisons au contact arrière. L’incorporation d’argent dans la composition du CIGS a également amélioré significativement les performances des cellules ultraminces, pour aboutir à une efficacité de 14.9% (avec 540 nm d’ACIGS, sans couche antireflet), proche du record actuel de 15.2% (avec couche antireflet et 490 nm de CIGS). En parallèle, l’ajout d’une couche de passivation en alumine à l’interface entre le CIGS (470 nm) et le Mo a été étudiée, et a conduit à une augmentation de la tension de circuit ouvert de 55 mV. Dans un deuxième temps, une nouvelle architecture de contact arrière réfléchissant a été développée. Elle consiste en un miroir d’argent encapsulé dans des couches d’oxydes transparents conducteurs. A l’aide d’observations au microscope électronique en transmission, il a été montré que ce contact arrière est compatible avec la co-évaporation de CIGS à des températures ≥500°C. Grâce à une haute réflectivité et un contact ohmique avec le CIGS, il a mené à une amélioration de l’efficacité de 12.5% à 13.5% et du courant de court-circuit de 26.2 mA/cm² à 28.9 mA/cm² par rapport à un contact arrière standard en molybdène. Cette nouvelle architecture ouvre la voie à une augmentation du rendement photovoltaïque des cellules solaires CIGS ultraminces ainsi qu’à de nouvelles stratégies de piégeage optique
Reducing the absorber thickness of thin-film photovoltaic devices is a promising way to improve their industrial competitiveness, thanks to a lower material usage and an increased throughput. It can also increase their efficiency due to a shorter pathway for the separation of photogenerated charge carriers. Still, the efficiency of ultrathin Cu(In,Ga)Se ₂ -based (CIGS) solar cells , which have an absorber thickness ≤500 nm that is approximately 5 times thinner than standard devices, is limited by two phenomena: the non-radiative recombination of charge carriers at the back contact and the incomplete absorption of the incident light. Several strategies were studied in order to mitigate those losses. First, the composition of ultrathin CIGS layers was optimized to create a grading of the semiconductor’s conduction band minimum. The resulting electric field contributes to a better charge carrier separation and a lower back contact recombination rate. The incorporation of silver in the CIGS composition greatly improved the performances of ultrathin cells, leading to an efficiency of 14.9% (540 nm of ACIGS, without antireflection coating), close to the current record of 15.2% (490 nm of CIGS, with antireflection coating). Besides, the addition of an alumina passivation layer at the interface between CIGS (470 nm) and Mo was also investigated, and resulted in an improvement of the open-circuit voltage of 55 mV. Second, a novel architecture of reflective back contacts was developed. It consists of a silver mirror that is encapsulated with layers of transparent conductive oxides. Based on a transmission electron microscopy study, this back contact was shown to be compatible with the co-evaporation of CIGS at 500°C or more. Thanks to a high reflectivity and an ohmic contact with CIGS, it led to an increase of the efficiency from 12.5% to 13.5% and of the short-circuit current from 26.2 mA/cm² to 28.9 mA/cm² as compared to cells with a standard molybdenum back contact. This reflective back contact paves the way toward higher photovoltaic efficiencies as well as novel strategies for further light trapping

Dans cette thèse nous évaluons le potentiel de cellules solaires micrométriques pour une utilisation sous flux concentré. Le but de l’étude est de mettre au point une technologie photovoltaïque à haut rendement, basée sur des technologies de grandes surfaces pour obtenir de fortes productivités, qui soit en même temps économe en matières premières pour respecter les contraintes imposées par un développement du photovoltaïque à l’échelle du terawatt. La miniaturisation des cellules solaires permet d’obtenir une architecture peu résistive, qui évacue efficacement la chaleur. Les microcellules sont donc adaptées à la concentration lumineuse. Des prototypes sont fabriqués, grâce à des techniques de photolithographie. Leur test permet d’évaluer leur rendement. Un gain absolu de 5% de rendement a été mesuré; un rendement maximum de 21. 3% sur une cellule de 50 µm de diamètre à une concentration de ×475 est atteint. Les caractéristiques du régime de forte illumination sont étudiées pour la première fois sur Cu(In,Ga)Se2. La photoconductivité de cet absorbeur est examinée. L’écrantage du champ électrique de l’hétérojonction Cu(In,Ga)Se2 sous fort flux est simulé numériquement et semble expliquer l’influence de l’intensité lumineuse sur la collecte des porteurs, mise en évidence expérimentalement. La possibilité d’une application industrielle est envisagée grâce à la fabrication de microcellules à absorbeur localisé, qui a permis de déterminer une faible vitesse de recombinaison sur les surfaces latérales des cellules (< 4 103 cm/s). Une technique de dépôt sélective, l’électrodépôt, a permis la synthèse de CuInSe2 sur des microélectrodes
In this thesis we explored the potential of thin film microscale concentrator solar cells. The aim of the study is to develop a highly efficient photovoltaic technology, based on large-area processes for high throughput, and which is raw-material thrifty to meet the constraints of terawatt development. The miniaturization of thin film solar cells leads to a low resistive architecture, with easy thermal management, which is therefore adapted to the concentrating regime. The scale effects are studied from an analytical and numerical point of view. Prototype Cu(In,Ga)Se2 solar cells are fabricated with help of photolithography techniques and tested to evaluate the performance of the microcells. A 5% absolute efficiency increase was measured, which led to a 21. 3% efficiency of a 50 µm diameter microcell at a concentration of ×475. The influence of the incident spectra is highlighted. The specific features of the high illumination regime are studied for the first time on Cu(In,Ga)Se2. The photoconductive behavior of Cu(In,Ga)Se2 is analyzed. The screening of the electric field in the Cu(In,Ga)Se2 heterojunction under high light fluxes is evidenced by simulation and may explain the influence of the illumination level on the collection efficiency observed experimentally. The possibility of an industrial application is tackled via the fabrication of mesa delineated microcells, which proves that the edge surface of the microcells have a low recombination velocity (< 4 103 cm/s). A bottom-up approach is studied via electrodeposition. This selective deposition technique enables the synthesis of CuInSe2 on microelectrodes

En quelques années, l'efficacité des cellules solaires à base de Cu(In,Ga)Se2 (CIGS) est passée de 20% à 22.6%. La rapidité de ce développement montre que le CIGS est un matériaux idéal pour les technologies solaires en couches minces. Pourtant, le coût de production cette technologie doit encore être abaissé pour une meilleure compétitivité. La fabrication d'un module avec une couche CIGS plus fine permettrait d'augmenter la production d'une usine et de réduire sa consommation en métaux. Ce travail de thèse vise à réduire l'épaisseur du CIGS d'un standard de 2.0-2.5 µm à une épaisseur inférieure à 500 nm sans altérer les performances des cellules. Cependant, comme rapporté dans la littérature, nous avons observé une diminution des rendements, ce que nous avons analysé en détail en comparant simulations et caractérisations d'échantillons. Celle-ci est causée à la fois par une faible absorption de la lumière dans la couche de CIGS et par un impact important du contact arrière (fortes recombinaisons et faible réflectivité). Pour dépasser ces limites, nous démontrons à la fois théoriquement et expérimentalement que le contact arrière en molybdène peut être remplacé par un oxyde transparent conducteur couplé à un miroir métallique. Nous obtenons de cette manière de meilleurs rendements de cellules. Pour atteindre ce résultat, une optimisation du dépôt de CIGS a été nécessaire. De plus, nous prouvons qu'une couche d'oxyde perforée, insérée entre le CIGS et le contact arrière, limite les recombinaisons des porteurs de charges et réduit l'influence des courants parallèles. Au final, nous avons fabriqué une cellule avec un rendement de 10.7% sur SnO2:F passivé par Al2O3
In the past three years, record efficiency of Cu(In,Ga)Se2 (CIGS) based solar cells has improved from 20% up to 22.6%. These results show that CIGS absorber is ideal for thin-film solar cells, even if this technology could be more competitive with a lower manufacture cost. The fabrication of devices with thinner CIGS absorbers is a way to increase the throughput of a factory and to reduce material consumption. This PhD thesis aims to develop cells with a CIGS thickness below 500 nm instead of the conventional 2.0-2.5 µm. However, as reported in the literature, we observed a decrease in cell performance. We carefully analyzed this effect by the comparison between simulations and sample characterizations: it is attributed, on one hand, to a lack of light absorption in the CIGS layer and, on the other hand, to an increased impact of the back-contact (high recombination and low reflectivity). To resolve these problems, we demonstrated theoretically and experimentally that the use of an alternative back-contact, other than molybdenum, such as a transparent conducting oxide coupled with a light reflector, improves the cell efficiency. To achieve this result, an optimization of the CIGS deposition was necessary. Moreover, we proved that a porous oxide layer inserted between the CIGS and the back-contact limits the charge-carrier recombination and removes some parasitic resistance. Finally, an efficiency of 10.7% was achieved for a 480-nm-thick CIGS solar cell with a SnO2:F back-contact passivated with a porous Al2O3 layer

Cu(In,Ga)Se2 (CIGS) is one of the most promising semiconductor compounds for large-scale production of efficient, low-cost thin film solar cells, and several research institutes have announced their plans for CIGS production lines. But for the CIGS technology to become a commercial success, a number of issues concerning manufacturability, product definition, and long-term stability require further attention. Several studies indicate that CIGS-based modules are stable over many years in field operation. At the same time, it is shown in the present work that they may have difficulties in passing standard accelerated lifetime test procedures like the IEC 1646 damp heat test. In particular, CIGS modules are sensitive to humidity penetrating through the module encapsulation, which will increase the resistive losses in the front contact and cause severe corrosion of the back contact. It is also shown that cells experience degradation in both voltage and fill factor, and the causes of these effects are addressed. By concentrating the light falling onto a solar cell, the device will deliver a higher power output per illuminated absorber area, which can lower the electricity production costs. For CIGS-based solar cells, low-concentrated illumination could be an economically viable approach. In this work it is shown that the yearly performance of a photovoltaic system with CIGS modules can be significantly improved at a moderate cost by using parabolic aluminum mirrors as concentrating elements. However, in order to avoid detrimental power losses due to high temperatures and current densities, the modules need to be designed for the higher light intensity and to be sufficiently cooled during operation. A design where the front contact of the module is assisted by a metal grid has shown promising results, not only for concentrated illumination but also for normal operation. The benefits are enhanced window processing tolerance and throughput, as well as improved degrees of freedom of the module geometry.

Dissertation (Ph. D.)--University of Akron, Dept. of Chemical Engineering, 2007.
"December, 2007." Title from electronic dissertation title page (viewed 03/12/2008) Advisor, Steven S. C. Chuang; Committee members, Lu-Kwang Ju, Edward Evans, W. B. Arbuckle, Stephen Z. D. Cheng; Department Chair, Lu-Kwang Ju; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thin-film solar cells based on Cu(In,Ga)Se2 contain a thin buffer layer of CdS in their standard configuration. In order to avoid cadmium in the device for environmental reasons, Cd-free alternatives are investigated. In this thesis, ZnO-based films, containing Mg or S, grown by atomic layer deposition (ALD), are shown to be viable alternatives to CdS. The CdS is an n-type semiconductor, which together with the n-type ZnO top-contact layers form the pn-junction with the p-type Cu(In,Ga)Se2. From device modeling it is known that a buffer layer conduction band (CB) position of 0-0.4 eV above that of the Cu(In,Ga)Se2 layer is consistent with high photovoltaic performance. For the Cu(In,Ga)Se2/ZnO interface this position is measured by photoelectron spectroscopy and optical methods to –0.2 eV, resulting in increased interface recombination. By including sulfur into ZnO, a favorable CB position to Cu(In,Ga)Se2 can be obtained for appropriate sulfur contents, and device efficiencies of up to 16.4% are demonstrated in this work. From theoretical calculations and photoelectron spectroscopy measurements, the shift in the valence and conduction bands of Zn(O,S) are shown to be non-linear with respect to the sulfur content, resulting in a large band gap bowing. ALD is a suitable technique for buffer layer deposition since conformal coverage can be obtained even for very thin films and at low deposition temperatures. However, deposition of Zn(O,S) is shown to deviate from an ideal ALD process with much larger sulfur content in the films than expected from the precursor pulsing ratios and with a clear increase of sulfur towards the Cu(In,Ga)Se2 layer. For (Zn,Mg)O, single-phase ZnO-type films are obtained for Mg/(Zn+Mg) < 0.2. In this region, the band gap increases almost linearly with the Mg content resulting in an improved CB alignment at the heterojunction interface with Cu(In,Ga)Se2 and high device efficiencies of up to 14.1%.

Dans cette thèse, nous avons étudié la conception, le prototypage et la caractérisation de microsystèmes photovoltaïques à concentration à base de cellules solaires Cu(In,Ga)Se2. L'objectif est de réduire l'utilisation de matériaux rares en utilisant la concentration de la lumière, et bénéficier des effets de la miniaturisation, comme la dissipation de la chaleur et des pertes résistives inférieurs. Tout d'abord, la conception optique des systèmes à concentration sur la base des microlentilles sphériques est présentée. À l'aide d'un logiciel de tracés de rayon Zemax OpticStudio, nous avons évalué la meilleure combinaison d'éléments, l'épaisseur et les rayons de courbure des lentilles, ainsi que les tolérances de fabrication et de positionnement du système. Un système optique de 1 mm d'épaisseur avec un rapport géométrique de 100 et une tolérance angulaire de +/- 3,5 ° a été conçu. D'autre part, des procédés de fabrication ont été créés et optimisés pour fabriquer un prototype de 5x5 cm² avec 2500 microcellules. Le meilleur mini-module a montré un facteur de concentration de 72x avec une augmentation en valeur absolue de l'efficacité de + 1,6%. Ensuite, des études numériques et expérimentales ont été réalisées sur des systèmes basés sur des concentrateurs luminescents (LSC) et des concentrateurs paraboliques (CPC). Les LSC ont montré un facteur de concentration faible et souffraient de problèmes de répétabilité tandis que les CPC sont une solution très efficace, mais très difficile à fabriquer à l¿échelle du micron. Enfin, nous avons développé un code MATLAB pour estimer l'énergie produite des systèmes conçus, pour évaluer la pertinence des choix technologiques futurs
In this thesis, we studied the design, prototyping and characterization of micro-concentrated photovoltaic systems based on Cu(In,Ga)Se2 solar cells. The objective is to reduce the use of rare materials using the concentration of light, and benefit from the effect of miniaturization such as heat dissipation and lower resistive losses. First, the optical design of 1D and 2D concentrating systems based on spherical microlenses is presented. Using a ray-tracing software Zemax OpticStudio, we evaluated the best combination of elements, thickness and radii of curvature of the lenses, as well as the tolerances of fabrication and positioning of the system. An optical system of 1 mm thickness with a geometrical ratio of 100 and an angular tolerance of +/- 3.5° has been designed. Second, fabrication processes have been created and optimized to fabricate a 5x5 cm² prototypes with 2500 microcells. The best mini-module showed a concentration factor of 72x with an absolute increase of the efficiency of +1.6%. Third, numerical and experimental studies have been performed on concentrating systems based on Luminescent Solar Concentrators (LSC) and Compound Parabolic Concentrators (CPC). The LSC showed a low concentration factor and suffered from repeatability issues while the CPC is a very efficient solution but its specific geometry makes it difficult to fabricate at the micron scale. Finally, we developed a MATLAB code to estimate the producible energy of the designed systems, in order to evaluate the relevance of future technological choices that will be made

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

In this chapter, we investigate a way of improving solar cells performances. By focusing studies on optimizing the structural, the opto-electrical and electronic properties of materials that constitute the layers and interfaces of a solar device, such as electrical susceptibility, doping concentration, mobility of charge carriers and crystallographic structure, it is possible to improve the output parameters of a solar cell. Working on a CIGSe-based second-generation ultra-thin solar cell model, and using Zinc Sulfide (ZnS) as a window layer, and based on recent studies, vital information are found on the optimal values of these properties that may enhance the efficiency of the cell. A correct modeling of the device with a trusted software such as SCAPS and an appropriate set of the exact conditions and parameters of simulation allow to obtain very promising results. In particular, for nanoscale and microscale thicknesses of buffer and absorber layers materials respectively, and with an appropriate choice of other materials properties such as intrinsic doping concentration, electrons and holes mobilities, it is possible to record efficiencies and fill factors of more than 26% and 85% respectively. These values are very promising for solar energy harvesting technologies development through CIGSe – ZnS based solar devices.

Superoxide dismutase (SOD) is a crucial enzyme required to maintain the redox potential of the cells. It plays a vital role in protecting normal cells from reactive oxygen species (ROS) produced during many intracellular pathogens infections. SOD removes excess superoxide radicals (O2−) by converting them to hydrogen peroxide (H2O2) and molecular oxygen (O2). Several superoxide dismutase enzymes have been identified based on the metal ion as a cofactor. Human SOD differs from the intracellular pathogens in having Cu/Zn and Mn as metal cofactors. However, SOD of intracellular pathogens such as Trypanosoma, Leishmania, Plasmodium, and Mycobacterium have iron (Fe) as metal cofactors. Iron Superoxide Dismutase (FeSOD) is an essential enzyme in these pathogens that neutralizes the free radical of oxygen (O−) and prevents the formation of Peroxynitrite anion (ONOO−), helping the pathogens escape from redox-based cytotoxic killing. Moreover, most intracellular bacteria hold MnSOD or FeSOD in their cytoplasm such as Salmonella and Staphylococcus, whereas periplasm of some pathogenic bacteria and fungi are also cofactors with Cu/Zn and identified as CuZnSOD. This chapter will review the various types SOD present in intracellular pathogens and their role in the survival of these pathogens inside their host niche.

Abstract This chapter describes CDC’s evolving response to HIV/AIDS in the United States in the modern era. Early AIDS investigations required a specific case definition and a national surveillance system. The AIDS case definition was expanded multiple times as understanding of the spectrum of HIV disease and affected populations improved. A controversial aspect of a 1993 revision was inclusion of a CD4 cell count threshold (&lt;200 cells/cu mm), which greatly increased the number of people considered to have AIDS. Introduction of antiretroviral therapy in the mid-1990s interrupted HIV’s previously predictable natural history, obscuring interpretation of trends and disease estimates. In 1999, CDC recommended name-based HIV reporting, after much controversy on which identifier to use to ensure confidentiality. In 2019, a national plan for ending the US epidemic was announced, emphasizing early HIV diagnosis and treatment, access to PrEP, detection of clusters based on phylogenetic analyses, and focus on most heavily affected populations and locations.

Schiff base ligands or compounds are useful in modern inorganic chemistry. Numerous transition metal-based catalysts have been synthesized with Schiff base scaffolds. The application of such Schiff bases is also found in biological studies. Herein, we have discussed the various synthetic procedures of diversified Schiff base compounds and their metal complexes. The biological activity of those complexes has also been delineated in this chapter with special emphasis. Various metal complexes [Co(II), Ni(II), Cu(II), Zn(II) and Fe(III)] with different Schiff base compounds displayed anti-fungal activity. Similarly, anti-viral activity was seen with Co(II) and Pd(II) metal complexes. Many Schiff base-metal complexes are found, which showed anti-cancer activity against various carcinoma cells like HpG2, MCF-7, A549, HCT116, Caco-2 and PC-3. Similarly, the transition metal complexes (generally 1st and 2 nd row) of Schiff bases also exhibited good anti-bacterial activity against various bacterial strains. The ionic-liquid-tagged Schiff bases have also been found to be good anti-microbial agents.

Many of the critical reactions considered in this book involve the addition or subtraction of protons from oxides. In this chapter, we consider another species that can change oxide charge distributions and reactivity dramatically: the electron. Many oxides contain cations that have access to more than one oxidation state in water. Cations in these oxides can either donate or accept electrons to change their charge, or oxidation state. Oxidation reactions involve the loss of electrons as they are donated to other species, resulting in an increase in the cation charge or valence, whereas reduction reactions involve the capture of an electron resulting in a decrease in the cation valence. Below, the basics of electrochemistry are first described in the context of the redox chemistry of water and representative oxide systems. Second, we describe the fundamentals of electron-transfer reactions in oxides and the impact of electron transfer on the acid–base, ion-exchange, and ligand-exchange reactions of the host oxide. Finally, we discuss the behavior of oxides in electrochemical energy storage devices and the role that nanotechnology has in optimizing electrochemical performance. Electrochemical reactions are typically written in the context of the geometry of a battery or a galvanic cell. For the cell shown in Figure 11.2, which contains metal electrodes immersed in aqueous solutions containing solvated cations, the net reaction can be written as . . . Cu°(s)+2Fe3+ (aq) ⇄2Fe2+ (aq)+Cu2+ (aq) (11.1). . . In this reaction, Cu metal is being oxidized to form Cu(II), whereas Fe(III) is being reduced to form Fe(II). The individual oxidation and reduction reactions leading to Eq. 11.1 are referred to as half-reactions: Cu°(s) ⇄Cu2+ (aq)+2e- Eo =−0.34 V (11.2) 2Fe3+ (aq) ⇄2Fe2+ (aq)+ Fe 2- (aq) Eo =+0.77 V (11.3) . . . The net result of Eqs. 11.2 and 11.3 in the context of Figure 11.2 is the transfer of electrons from the Cu-containing compartment in which oxidation occurs, which is called the anode, to the Fe-containing compartment in which reduction occurs, which is called the cathode. This electron transfer generates an electric current, a charge-compensating ion current (in the salt bridge), as well as a voltage.

The structure, magnetic and magnetocaloric properties of Nd2Fe17−xCox (x = 0; 1; 2; 3, 4) and Gd2Fe17-xCux (x = 0, 0.5, 1 and 1.5) solid solutions have been studied. For this purpose, these samples were prepared by arc melting and subsequent annealing at 1073 K for a 7 days. Structural analysis by Rietveld method on X-ray diffraction (XRD) have determined that these alloys crystallize in the rhombohedral Th2Zn17-type structure (Space group R¯3 m) and the substitution of iron by nickel and copper leads to a decrease in the unit cell volume. The Curie temperature (TC) of the prepared samples depends on the nickel and copper content. Based on the Arrott plot, these analyses show that Nd2Fe17-xCox exhibits a second-order ferromagnetic to paramagnetic phase transition around the Curie temperature. These curves were also used to determine the magnetic entropy change ∆SMax and the relative cooling power. For an applied field of 1.5 T, ∆SMax increase from 3.35 J/kg. K for x = 0 to 5.83 J/kg. K for x = 2. In addition the RCP increases monotonously. This is due to an important temperature range for the magnetic phase transition, contributing to a large ∆SMax shape. Gd2Fe17-xCux solid solution has a reduction of the ferromagnetic phase transition temperature from 475 K (for x = 0) to 460 K (for x = 1.5) is due to the substitution of the magnetic element (Fe) by non-magnetic atoms (Cu). The magnetocaloric effect was determined in the vicinity of the Curie temperature TC. By increasing the Cu content, an increase in the values of magnetic entropy (∆SMax) in a low applied field is observed.

This paper presents experimental results and analysis of a new high-power Cu/Cu2+ thermogalvanic cell and its comparison with previous results. Past researches were mostly focused on finding the best redox couples and electrode materials [1, 2], however, they generally lacked a comparison of power conversion efficiency (η) dependence on cell geometry. This inspired our interest in exploring the relation of η, internal resistance, maximum power, and cell geometry. Based on previous results [3], a low internal resistance, variable orientation thermogalvanic cell was designed to achieve the highest power output. Experimental results of the Seebeck coefficient (α = ∂E/∂T), power density, and η of Cu/Cu2+ electrolytes in various molar concentrations showed that 0.7M CuSO4 electrolyte has maximum α and power output of 0.7196 mV/°C and 3.17 μW/cm2, respectively. Power output of the new cell has significant improvement which is 219 times greater than previous research. This paper also presents economical aspects of Cu/Cu2+ thermogalvanic cells relative to ferri/ferrocyanide cells.