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Künecke, Ulrike [Verfasser], and Peter [Akademischer Betreuer] Wellmann. "Charakterisierung von Inhomogenitäten an CIGSSe-Solarzellenabsorbern im Rasterelektronenmikroskop / Ulrike Künecke. Gutachter: Peter Wellmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1065269943/34.
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Keller, Jan [Verfasser], and Jürgen [Akademischer Betreuer] Parisi. "Charakterisierung und Simulation von sequentiell prozessierten CIGSSe-Solarzellen mit chemisch gradierter Absorberschicht : Möglichkeiten und Einschränkungen eines eindimensionalen Ansatzes / Jan Keller. Betreuer: Jürgen Parisi." Oldenburg : IBIT - Universitätsbibliothek, 2012. http://d-nb.info/1026283833/34.
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Pohlner, Stephan [Verfasser], Carsten [Gutachter] Ronning, Gerhard [Gutachter] Franz, and Friedrich [Gutachter] Reinert. "Impact of indium sulphide based buffer layers on the electrical properties of CIGSSe thin film solar cells / Stephan Pohlner ; Gutachter: Carsten Ronning, Gerhard Franz, Friedrich Reinert." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177599791/34.
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Saeed, Mahfouz Ali. "ELECTROCHEMICAL FABRICATION OF THIN FILM PHOTOVOLTAIC DEVICES (CIGS & CIGSS)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396265882.
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Kadam, Ankur. "PREPARATION OF EFFICIENT CUIN1-XGAXSE2-YSY/CDS THIN-FILM SOLAR CELLS BY OPTIMIZING THE MOLYBDENUM BACK CONTACT AND USING DIETHYL." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4230.
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High efficiency CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells were prepared by optimizing the Mo back contact layer and optimizing the parameters for preparing CIGSS absorber layer using diethylselenide as selenium source. The Mo film was sputter deposited on 2.5 cm x 10 cm soda-lime glass using DC magnetron sputtering for studying the adhesion and chemical reactivity with selenium and sulfur containing gas at maximum film growth temperature. Mo being a refractory material develops stresses, nature of which depends on the deposition power and argon pressure. It was found that the deposition sequence with two tensile stressed layers deposited at 200W and 5 x 10-3 Torr argon pressure when sandwiched between three compressively stressed layers deposited at 300 W power and 0.3 x 10-3 Torr argon pressure had the best adhesion, limited reactivity and compact nature. An organo-metallic compound, diethylselenide (DESe) was developed as selenium precursor to prepare CIGSS absorber layers. Metallic precursors Cu-In-Ga layers were annealing in the conventional furnace in the temperature range of 475oC to 515 oC and in the presence of a dilute DESe atmosphere. The films were grown in an indium rich regime. Systematic approaches lead to the optimization of each step involved in the preparation of the absorber layer. Initial experiments were focused on obtaining the range of maximum temperatures required for the growth of the film. The following experiments included optimization of soaking time at maximum temperature, quantity of metallic precursor, and amount of sodium in terms of NaF layer thickness required for selenization. The absorber surface was coated with a 50 to 60 nm thick layer of CdS as hetero-junction partner by chemical bath deposition. A window bi-layer of i:ZnO/ZnO:Al was deposited by RF magnetron sputtering. The thickness of i:ZnO was increased to reduce the shunt resistance to improve open circuit voltage. The cells were completed by depositing a Cr/Ag front contact by thermal evaporation. Efficiencies greater than 13% was achieved on glass substrates. The performance of the cells was co-related with the material properties.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
6
Kulkarni, Sachin. "EFFECT OF COMPOSITION, MORPHOLOGY AND SEMICONDUCTING PROPERTIES ON THE EFFICIENCY OF CUIN1-XGAXSE2-YSY THIN-FILM SOLAR CELLS PRE." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2938.
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A rapid thermal processing (RTP) reactor for the preparation of graded CuIn1-xGaxSe2-ySy (CIGSeS) thin-film solar cells has been designed, assembled and is being used at the Photovoltaic Materials Laboratory of the Florida Solar Energy Center. CIGSeS films having the optimum composition, morphology, and semiconducting properties were prepared using RTP. Initially films having various Cu/(In+Ga) ratios were prepared. In the next step selenium incorporation in these films was optimized, followed by sulfur incorporation in the surface to increase the bandgap at the surface. The compositional gradient of sulfur was fine-tuned so as to increase the conversion efficiency. Materials properties of these films were characterized by optical microscopy, SEM, AFM, EDS, XRD, GIXRD, AES, and EPMA. The completed cells were extensively studied by electrical characterization. Current-voltage (I-V), external and internal quantum efficiency (EQE and IQE), capacitance-voltage (C-V), and light beam induced current (LBIC) analysis were carried out. Current Density (J)-Voltage (V) curves were obtained at different temperatures. The temperature dependence of the open circuit voltage and fill factor has been estimated. The bandgap value calculated from the intercept of the linear extrapolation was ~1.1-1.2 eV. Capacitance-voltage analysis gave a carrier density of ~4.0 x 1015 cm-3. Semiconductor properties analysis of CuIn1-xGaxSe2-ySy (CIGSeS) thin-film solar cells has been carried out. The values of various PV parameters determined using this analysis were as follows: shunt resistance (Rp) of ~510 Ohms-cm2 under illumination and ~1300 Ohms-cm2 in dark, series resistance (Rs) of ~0.8 Ohms-cm2 under illumination and ~1.7 Ohms-cm2 in dark, diode quality factor (A) of 1.87, and reverse saturation current density (Jo) of 1.5 x 10-7A cm-2. The efficiency of 12.78% obtained during this research is the highest efficiency obtained by any University or National Lab for copper chalcopyrite solar cells prepared by RTP. CIGS2 cells have a better match to the solar spectrum due to their comparatively higher band-gap as compared to CIGS cells. However, they are presently limited to efficiencies below 13% which is considerably lower than that of CIGS cells of 19.9%. One of the reasons for this lower efficiency is the conduction band offset between the CIGS2 absorber layer and the CdS heterojunction partner layer. The band offset value between CIGS2 and CdS was estimated by a combination of ultraviolet photoelectron spectroscopy (UPS) and Inverse Photoemission Spectroscopy (IPES) to be -0.45 eV, i.e. a cliff is present between these two layers, enhancing the recombination at the junction, this limits the efficiency of CIGS2 wide-gap chalcopyrite solar cells.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD
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Kaul, Ashwani. "Optimization of Process Parameters for Faster Deposition of CuIn1-xGaxS2 and CuIn1-xGaxSe2-ySy Thin Film Solar Cells." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5336.
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Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. Among all the thin film technologies, CuInGaSe2 (CIGS) thin film solar cells have achieved the highest efficiency. However, the high price of photovoltaic (PV) modules has been a major factor impeding their growth for terrestrial applications. Reduction in cost of PV modules can be realized by several ways including choosing scalable processes amenable to large area deposition, reduction in the materials consumption of active layers, and attaining faster deposition rates suitable for in-line processing. Selenization-sulfurization of sputtered metallic Cu-In-Ga precursors is known to be more amenable to large area deposition. Sputter-deposited molybdenum thin film is commonly employed as a back contact layer for CIGS solar cells. However, there are several difficulties in fabricating an optimum back contact layer. It is known that molybdenum thin films deposited at higher sputtering power and lower gas pressure exhibit better electrical conductivity. However, such films exhibit poor adhesion to the soda-lime glass substrate. On the other hand, films deposited at lower discharge power and higher pressure although exhibit excellent adhesion show lower electrical conductivity. Therefore, a multilayer structure is normally used so as to get best from the two deposition regimes. A multi-pass processing is not desirable in high volume production because it prolongs total production time and correspondingly increases the manufacturing cost. In order to make manufacturing compliant with an in-line deposition, it is justifiable having fewer deposition sequences. Thorough analysis of pressure and power relationship of film properties deposited at various parameters has been carried out. It has been shown that it is possible to achieve a molybdenum back contact of desired properties in a single deposition pass by choosing the optimum deposition parameters. It is also shown that the film deposited in a single pass is actually a composite structure. CIGS solar cells have successfully been completed on the developed single layer back contact with National Renewable Energy Laboratory (NREL) certified device efficiencies >11%. The optimization of parameters has been carried out in such a way that the deposition of back contact and metallic precursors can be carried out in identical pressure conditions which is essential for in-line deposition without a need for load-lock. It is know that the presence of sodium plays a very critical role during the growth of CIGS absorber layer and is beneficial for the optimum device performance. The effect of sodium location during the growth of the absorber layer has been studied so as to optimize its quantity and location in order to get devices with improved performance. NREL certified devices with efficiencies >12% have been successfully completed.Ph.D.
Doctorate
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering
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Kumar, Bhaskar. "ZINC CADMIUM SULPHIDE AND ZINC SULPHIDE AS ALTERNATIVE HETEROJUNCTION PARTNERS FOR CIGS2 SOLAR CELLS." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4052.
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Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with alternative heterojunction partner such as ZnS. With varying ratio of Zn/ (Zn+Cd) in ZnxCd1-xS a range of bandgap energies can be obtained and thus an optimum band offset can be engineered. For reducing interface dominated recombination better lattice match between absorber and heterojunction partners is desirable. Although CdS has better lattice match with CuIn1-xGaxS2 absorber layer, same is not true for CuIn1-xGaxS2 absorber layers. Utilizing ZnxCd1-xS as heterojunction partner provides a range of lattice constant (between aZnS= ~5.4 Ǻ and aCdS= ~5.7 Ǻ) depending on Zn/(Zn+Cd). Therefore better lattice match can be obtained between heterojunction partner and absorber layer. Better lattice match will lead to lower interface dominated recombination, hence higher open circuit voltages. In the present study chemical bath deposition parameters are near optimized for high efficiency CIGS2 Solar cells. Effect of various chemical bath deposition parameters on device performance was studied and attempts were made to optimize the deposition parameters in order to improve the device performance.In/(In+Ga) ratio in absorber layer is varied to obtain good lattice match and optimum band alignment. Solar cells with conversion efficiencies comparable to conventional CdS/CIGS2 has been obtained with ZnxCd1-xS /CIGS2. High short current as well as higher open circuit voltages were obtained with ZnxCd1-xS as alternative heterojunction partner for CIGS2 solar cells as compared to SLG/Mo/CIGS2/ CdS / i-ZnO/ZnO:Al.M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE
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Pethe, Shirish A. "Optimization of process parameters for reduced thickness CIGSeS thin film solar cells." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4623.
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With the advent of the 21st century, one of the serious problems facing mankind is harmful effects of global warming. Add to that the ever increasing cost of fuel and the importance of development of clean energy resources as alternative to fossil fuel has becomes one of the prime and pressing challenges for modern science and technology in the 21st century. Recent studies have shown that energy related sources account for 50% of the total emission of carbon dioxide in the atmosphere. All research activities are focused on developing various technologies that are capable of converting sunlight into electricity with high efficiency and can be produced using a cost-effective process. One of such technologies is the CuIn[sub1-x]Ga[subx]Se[sub2] (CIGS) and its alloys that can be produced using cost-effective techniques and also exhibit high photo-conversion efficiency. The work presented here discusses some of the fundamental issues related to high volume production of CIGS thin film solar cells. Three principal issues that have been addressed in this work are effect of reduction in absorber thickness on device performance, micrononuniformity involved with amount of sodium and its effect on device performance and lastly the effect of working distance on the properties of molybdenum back contact. An effort has been made to understand the effect of absorber thickness on PV parameters and optimize the process parameters accordingly. Very thin (<1 [micro]m) absorber film were prepared by selenization using metallorganic selenium source in a conventional furnace and by RTP using Se vapor. Sulfurization was carried out using H2S gas. Devices with efficiencies reaching 9% were prepared for very thin (<1 [micro]m) CIGS and CIGSeS thin films. It was shown through this work that the absorber thickness reduction of 64% results in the efficiency drop of only 32%. With further optimization of the reaction process of the absorber layer as well as the other layers higher efficiencies can be achieved. The effect of sodium on the device performance is experimentally verified in this work. To the best of our knowledge the detrimental effect of excess sodium has been verified by experimental data and effort has been made to correlate the variation in PV parameter to theoretical models of effect of sodium. It has been a regular practice to deposit thin barrier layer prior to molybdenum deposition to reduce the micrononuniformities caused due to nonuniform out diffusion of sodium from the soda lime glass. However, it was proven in this work that an optimally thick barrier layer is necessary to reduce the out diffusion of sodium to negligible quantities and thus reduce the micrononuniformities. Molybdenum back contact deposition is a bottleneck in high volume manufacturing due to the current state of art where multi layer molybdenum film needs to be deposited to achieve the required properties. In order to understand and solve this problem experiments were carried out. The effect of working distance (distance between the target and the substrate) on film properties was studied and is presented in this work. During the course of this work efforts were taken to carry out a systematic and detailed study of some of the fundamental issues related to CIGS technology and particular for high volume manufacturing of CIGS PV modules and lay a good foundation for further improvement of PV performance of CIGS thin film solar cells prepared by the two step process of selenization and sulfurization of sputtered metallic precursors.ID: 030423396; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 108-116).
Ph.D.
Doctorate
Department of Electrical Engineering and Computer Science
Engineering and Computer Science
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Jehl, Zacharie. "Realization of ultrathin Copper Indium Gallium Di-selenide (CIGSe) solar cells." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112058/document.
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Nous étudions la possibilité de réaliser des cellules à base de diséléniure de cuivre, indium et gallium (CIGSe) à absorbeur ultra-mince, en réduisant l’épaisseur de la couche de CIGSe de 2500 nm jusqu’à 100 nm, tout en conservant un haut rendement de conversion.Grâce à l’utilisation d’outils de simulation numérique, nous étudions l’influence de la réduction d’épaisseur de l’absorbeur sur les paramètres photovoltaïques de la cellule. Une importante dégradation du rendement est observée, principalement attribuée à une réduction de la fraction de lumière absorbée par le CIGSe ainsi qu’à une collecte des porteurs de charge réduite dans les dispositifs ultraminces. Des solutions permettant de surmonter ces problèmes sont proposées et leur influence potentielle est numériquement simulée ; nous démontrons qu’une ingénierie de face avant (couche tampon alternative, couche anti-réfléchissante…) et de face arrière (contact arrière réfléchissant, diffusion de la lumière) sur une cellule CIGSe à absorbeur ultramince permet de potentiellement améliorer le rendement de la cellule solaire au niveau de celui d’une cellule à absorbeur référence (2.5 μm).Grâce à l’utilisation de techniques de gravure chimique sur des échantillons standards de CIGSe épais, nous réalisons des cellules solaires avec différentes épaisseurs d’absorbeurs, et nous étudions l’influence de l’épaisseur du CIGSe sur les paramètres photovoltaïques des cellules. Le comportement similaire aux simulations numériques.Une ingénierie du contact avant sur des cellules CIGSe à différentes épaisseurs est réalisée pour spécifiquement améliorer l’absorption dans la couche de CIGSe. Nous étudions l’influence d’une couche tampon alternative de ZnS, de la texturation de la fenêtre avant de ZnO:Al, et d’une couche anti-reflet sur la cellule solaire. D’importantes améliorations sont observées quelque soit l’épaisseur de la couche de CIGSe, ce qui permet d’obtenir des rendements de conversions supérieurs à ceux obtenus dans la configuration standard des dispositifs.Une ingénierie du contact arrière à basse température est également réalisée avec l’utilisation d’un procédé novateur combinant la gravure chimique du CIGSe avec un « lift-off » mécanique de la couche de CIGSe afin de la séparer du substrat de Molybdène. De nouveaux matériaux fortement réflecteur de lumière et précédemment incompatible avec le procédé de croissance du CIGSe sont utilisés comme contact arrière pour des cellules CIGSe ultra-minces. Une étude comparative en fonction de l’épaisseur de CIGSe entre des cellules avec contact arrière réfléchissant en Or (Au) et cellules solaires avec contact arrière standard Mo est effectuée. Le contact Au permet d’augmenter significativement le rendement de conversion des cellules solaires à absorbeur sub-microniques comparé au contact standard Mo avec un rendement de conversion supérieur à 10% obtenu sur une cellule CIGSe de 400 nm (comparé à 7.9% avec Mo).Afin de réduire encore plus l’épaisseur de la couche de CIGSe, jusque 100-200 nm, les modèles numériques montrent qu’il est nécessaire d’utiliser un réflecteur lambertien sur la face arrière de la cellule afin de maximiser l’absorption de la lumière. Un dispositif preuve de concept expérimental est réalisé avec une épaisseur de CIGSe de 200 nm et un réflecteur arrière lambertien, et ce dispositif est caractérisé par spectroscopie de transmission/réflexion. La réponse spectrale est déterminée en combinant des valeurs issues de simulation numérique et la mesure expérimental de l’absorption du dispositif. Nous calculons un courant de court circuit de 26 mA.cm-2 pour ce dispositif avec réflecteur lambertien, bien supérieur à ce qui est calculé pour la même structure sans réflecteur (15 mA.cm-2), et comparable au courant mesuré sur une cellule de référence de 2500 nm (28 mA.cm-2). L’utilisation de réflecteur lambertien pour des cellules CIGSe ultraminces est donc particulièrement adaptée pour maintenir de hauts rendementsIn this thesis, we investigate on the possibility to realize ultrathin absorber Copper Indium Gallium Di-Selenide (CIGSe) solar cells, by reducing the CIGSe thickness from 2500 nm down to 100 nm, while conserving a high conversion efficiency.Using numerical modeling, we first study the evolution of the photovoltaic parameters when reducing the absorber thickness. A strong decrease of the efficiency of the solar cell is observed, mainly related to a reduced light absorption and carrier collection for thin and ultrathin CIGSe solar cells. Solutions to overcome these problems are proposed and the potential improvements are modeled; we show that front side (buffer layer, antireflection coating) and back side (reflective back contact, light scattering) engineering of an ultrathin device can potentially increase the conversion efficiency up to the level of a standard thick CIGSe solar cell.By using chemical bromine etching on a standard thick CIGSe layer, we realize solar cells with different absorber thicknesses and experimentally study the influence of the absorber thickness on the photovoltaic parameters of the devices. Experiments show a similar trends to that observed in numerical modeling.Front contact engineering on thin CIGSe solar cell is realized to increase the specific absorption in CIGSe, including alternative ZnS buffer, front ZnO:Al window texturation and anti-reflection coating. Substantial improvements are observed whatever the CIGSe thickness, with efficiencies higher that the default configuration.A back contact engineering at low temperature is realized by using an innovative approach combining chemical etching of the CIGSe and mechanical lift-off of the CIGSe from the original Molybdenum (Mo) substrate. New highly reflective materials previously incompatible with the standard solar cell process are used as back contact for thin and ultrathin CIGSe solar cells, and a comparative study between standard Mo back contact and alternative reflective Au back contact solar cells is performed. The Au back reflector significantly enhance the efficiency of solar cell with sub-micrometer absorbers compared to the standard Mo back reflector; an efficiency higher than 10 % on a 400 nm CIGSe is obtained with Au back contact (7.9% with standard Mo back contact). For further reduction of the absorber thickness down to 100-200 nm, numerical modeling show that a lambertian back reflector is needed to fully absorb the incident light in the CIGSe. An experimental proof of concept device with a CIGSe thickness of 200 nm and a lambertian back reflector is realized and characterized by reflection/transmission spectroscopy, and the experimental spectral response is determined by combining simulation and experimentally measured absorption. A short circuit current of 26 mA.cm-2 is determined with the lambertian back reflector, which is much higher than what is obtained for the same device with no reflector (15 mA.cm-2), and comparable to the short circuit current measured on a reference 2500 nm thick CIGSe solar cell (28 mA.cm-2). Lambertian back reflectors are therefore found to be the most effective way to enhance the efficiency of an ultrathin CIGSe solar cell up to the level of a reference thick CIGSe solar cell
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Heinemann, Marc Daniel [Verfasser], Bernd [Akademischer Betreuer] Rech, Michael [Gutachter] Powalla, Bernd [Gutachter] Rech, and Susan [Gutachter] Schorr. "CIGSe superstrate solar cells : growth and characterization of CIGSe thin films on transparent conductive oxides / Marc Daniel Heinemann ; Gutachter: Michael Powalla, Bernd Rech, Susan Schorr ; Betreuer: Bernd Rech." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/115618021X/34.
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Shirolikar, Jyoti. "PREPARATION AND CHARACTERIZATION OF CIGSS SOLAR CELLS AND PV MODULE DATA ANALYSIS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4223.
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In this thesis, multiple activities have been carried out in order to improve the process of CIGSS solar cell fabrication on a 4" x 4" substrate. The process of CIGSS solar cell fabrication at FSEC's PV Materials Lab involves a series of steps that were all carried out manually in the past. A LABVIEW program has been written to carry out automated sputter deposition of Mo back contact, CuGa, In metallic precursors on a soda lime glass substrate using a stepper motor control for better uniformity. Further, selenization/ sulfurization of these precursors was carried out using rapid thermal processing (RTP). CIGS films were sulfurized using chemical bath deposition (CBD). ZnO:Al was deposited on the CIGSS films using RF sputtering. A separate LABVIEW program was written to automate the process of ZnO:Al deposition. Ni/Al contact fingers were deposited on the ZnO:Al layer using the e-beam evaporation technique. Further, in order to test these solar cells in-house, a simple current-voltage (IV) tracer was fabricated using LABVIEW. A quantum efficiency (QE) measurement setup was built with guidance from the National Renewable Energy Laboratory (NREL). Lastly, analysis of data from photovoltaic (PV) modules installed on the FSEC test site has been carried out using a LABVIEW program in order to find out their rate of degradation as time progresses. A 'C' program has also been written as an aid for keeping a daily log of errors in data and for troubleshooting of the same.M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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Souilah, Marc. "Étude cristallochimique de semi-conducteurs CIGSe pour cellules photovoltaïques en couches minces." Nantes, 2009. http://www.theses.fr/2009NANT2061.
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L’objectif de cette thèse était d’étudier la cristallographie de composés sous forme de poudre ayant des propriétés photovoltaïques, les CIGSe (CuIn1‑xGaxSe2). Ceux‑ci sont utilisés comme couche absorbante dans des cellules photovoltaïque en couche mince de seconde génération et commencent à être commercialisés, notamment aux USA et en Allemagne. Une ré‑investigation complète des composés poudre a ainsi été conduite par diffraction des rayons X sur poudre et monocristal, dans le but d’améliorer la compréhension des phases cristallines, notamment pour des taux de cuivre très faibles. Des calculs de structure électronique ont été entrepris sur des compositions particulières de CIGSe afin de mieux comprendre certaines propriétés. Le composé historique CuInSe2 a ainsi servi de modèle théorique car possédant de nombreuses références expérimentales dans la littérature. Enfin, des échantillons en couches minces de CIGSe ont été préparées pour une étude par microscopie électronique à transmission. Le but était de voir l’évolution de la qualité cristalline pour des forts taux de gallium, taux où les rendements des couches minces sont plus faiblesThis study mainly focuses on the crystallographic research of powder compounds with photovoltaic properties. They are used in photovoltaic thin film solar cell (2nd generation) as absorber layer. They have been produced and sold in the US and Germany in particular. A complete powder compounds re-investigation have been made by X-Ray diffraction on powder and single crystal. The aim of this research was to have a better comprehension of the crystalline phases, especially for copper poor compounds. Electronic structure calculation have been conducted on specific CIGSe composition to try to understand some special properties. The original compound CuInSe2 was used as theoretical model because many experimental references can be found in the literature. Finally, CIGSe thin-film sample have been prepared for a study by transmission electronic microscopy. The purpose was to check the crystal quality with high gallium content, because the efficiency of the solar cells tends to drop down as the gallium content increasing
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Marko, Hakim. "Développement de dispositifs photovoltaïques à base de CIGSe à grande bande interdite." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0003.
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Ces travaux de thèse ont pour objectif d'améliorer la compréhension de la dégradation observée des dispositifs photovoltaïques à base de Cu(ln,Ga)Se2 (ClGSe) à large bande interdite (EG > 1,2 eV), c'est-à-dire pour des rapports en gallium xGa=[Ga]/([ln]+[GaJ) supérieurs à 30 %. Deux axes de travail répondant à la problématique se sont dégagés, l'un focalisé sur la mise en place de protocoles de croissance par co-évaporation thermique spécifiques au CIGSe à grand gap, l'autre étant centré sur le développement de couche tampon alternative au CdS à base de Zn(O,S) déposé par couche atomique (ALD, en collaboration avec l'université d'Uppsala en Suède) et pulvérisation réactive. A forte teneur en gallium (xGa rv 50 %), il s'est avéré que la croissance du CIGSe, ainsi que sa stœchiométrie en cuivre constituent des facteurs clefs à contrôler afin d'améliorer sensiblement les propriétés photovoltaïques des dispositifs. Un modèle a été proposé afin de mieux comprendre l'influence du taux de cuivre à forte teneur en gallium. L'optimisation de la recette de Zn(O,S) déposé par ALD a également permis de maximiser les rendements de conversion des dispositifs jusqu'à des valeurs proches de 15 %. Il est suggéré que le contrôle de la stœchiométrie de la couche de Zn(O,S) a résulté en l'ajustement favorable de la discontinuité de bandes de conduction électroniques à l'interface avec le CIGSe. Le dépôt de la couche tampon alternative par pulvérisation réactive a révélé une relative innocuité pour la surface de l'absorbeurThe goal of this work is to improve the understanding of the experimental suboptimal electrical properties of solar cells based on large bandgap Cu(ln,Ga)Se2 (ClGSe), Le. EG > 1,2 eV and gallium content (xGa=[Ga]/([ln]+[Ga])) higher than 30 %. Ln order to try to answer to the problematic, the work have been focused, firstly, on the implementation of large bandgap ClGSe growth processes by thermal coevaporation and, secondly, on the development of CdS alternative buffer layer based on Zn(O,S) grown by atomic layer de position (AL D, in collaboration with the Uppsala University in Sweden) and reactive sputtering. At high Ga content (xGa rv 50 %), the ClGSe growth and its copper composition seems to be key factors for improving solar cells efficiencies. A model has been proposed in order to better understand the copper content effect at high gallium composition. The adjustment of the Zn(O,S) recipe grown by ALD allowed maximizing devices efficiencies close to 15 %. It is suggested that the control of the Zn(O,S) layer led to the favourable conduction band matching at the interface with the CIGSe. The Zn(O,S) de position by reactive sputtering showed a relative harmlessness for the CIGSe surface
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Fedele, Carine. "Construction automatisée des compilateurs : le système CIGALE." Nice, 1991. http://www.theses.fr/1991NICE4469.
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La méta-compilation est un sujet depuis longtemps exploré et les idées sont nombreuses. Mais les résultats obtenus ne sont pas encore satisfaisants. Il faut tout d'abord faire la différence entre les méta-compilateurs de langages expérimentaux et ceux de langages d'implémentation. Dans le premier cas, les performances des compilateurs générés ne sont pas importantes, et ces systèmes sont le plus souvent utilisés par des personnes qui ne souhaitent pas s'intéresser à la compilation. Dans le second cas, obtenir un compilateur peu rapide et produisant du code inefficace serait catastrophique. En effet, tous les logiciels reposant sur ce langage d'implémentation auraient des performances inacceptables, par exemple dans le monde industriel. Au contraire les utilisateurs du méta-compilateur sont compétents en compilation et souhaitent seulement que leur tâche soit facilitée. Peu de travaux existent dans ce dernier cas et c'est une lacune. Le système CIGALE est un système d'écriture de compilateurs basé sur le formalisme bien connu des grammaires attribuées. A partir d'une description syntactico-sémantique du langage (l'aspect lexical est implicite), CIGALE génère un compilateur pour ce langage produisant du code EM. Ce code EM est ensuite traité par les différentes phases d'ACK jusqu'à obtention de code efficace pour une machine réelle donnée. La description de la syntaxe du langage se fait grâce à une notation proche de la BNF ; celle de la sémantique est donnée grâce à l'utilisation d'un type abstrait. Ce type abstrait n'est pas figé et l'utilisateur fournira des outils pour les aspects non prévusCompiler-compilers are a well-known subject and many ideas have been explored. However, results are note entirely satisfactory. First, one should distinguish between compiler-compilers for experimental languages and those for implementation languages. In the first case, the efficiency of the generated compiler sis not important, and these systems are generally used bu people who do not wish to invest in compiler practice. In the second case, a resulting compiler which would be slow and generate inefficient code would be useless: all software products built using this implementation language would have unbearable performances, especially in the software world. On the contrary, users such a compiler-compiler are compiling practitioners and only ask for help in their task. Not much work is done in this last case and it is a pity. For an already long time, a theory of scanning an parsing has been developed. Today, automatically building a lexico-syntactic analyzer is easy. That is not the case for the other parts of the compiling process: contextual analysis and code generation. No « universal » theory is currently accepted by all scientists. The CIGALE system is a compiler writing system based on the well-known formalism of attribute grammars. From a description of the syntax and semantics of the language (the lexical aspect is implicit). CIGALE produces a compiler for this language generating EM code. This code is then processed by the ACK components until this language code is generated for a given actual machine. The language syntax is describing using a notation similar to BNF. The language semantics is described by the use of an abstract data type. This type is not frozen and the user can provide next tools for handling unforeseen language features. The thesis begins with the survey of nine formal semantic notations and of twenty compiler-compilers. The CIGALE system is then thoroughly xplained. The abstract data type for contextual analysis and dynamic semantics is then fully specified, and its use is demonstrated on a real size example. The thesis ends with the description of a higher-level notation deduced from this abstract data type
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Schönherr, Sven [Verfasser], Carsten Gutachter] Ronning, Thomas [Gutachter] [Hannappel, and Johannes [Gutachter] Windeln. "Elektro-optische Untersuchung von CIGSe-Dünnschichtsolarzellen / Sven Schönherr ; Gutachter: Carsten Ronning, Thomas Hannappel, Johannes Windeln." Jena : Friedrich-Schiller-Universität Jena, 2016. http://d-nb.info/1177612615/34.
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Möckel, Stefan [Verfasser], and Peter [Akademischer Betreuer] Wellmann. "Bildungsmechanismen bei der Herstellung von CIGSe Solarzellenabsorbern aus nanopartikulären Präkursorschichten / Stefan Möckel. Gutachter: Peter Wellmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1075562392/34.
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Jehl, Zacharie. "Réalisation de cellules solaires à base d'absorbeurs ultraminces de diséléniure de cuivre, d'indium et de gallium (CIGSe)." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00697615.
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Nous étudions la possibilité de réaliser des cellules à base de diséléniure de cuivre, indium et gallium (CIGSe) à absorbeur ultra-mince, en réduisant l'épaisseur de la couche de CIGSe de 2500 nm jusqu'à 100 nm, tout en conservant un haut rendement de conversion.Grâce à l'utilisation d'outils de simulation numérique, nous étudions l'influence de la réduction d'épaisseur de l'absorbeur sur les paramètres photovoltaïques de la cellule. Une importante dégradation du rendement est observée, principalement attribuée à une réduction de la fraction de lumière absorbée par le CIGSe ainsi qu'à une collecte des porteurs de charge réduite dans les dispositifs ultraminces. Des solutions permettant de surmonter ces problèmes sont proposées et leur influence potentielle est numériquement simulée ; nous démontrons qu'une ingénierie de face avant (couche tampon alternative, couche anti-réfléchissante...) et de face arrière (contact arrière réfléchissant, diffusion de la lumière) sur une cellule CIGSe à absorbeur ultramince permet de potentiellement améliorer le rendement de la cellule solaire au niveau de celui d'une cellule à absorbeur référence (2.5 μm).Grâce à l'utilisation de techniques de gravure chimique sur des échantillons standards de CIGSe épais, nous réalisons des cellules solaires avec différentes épaisseurs d'absorbeurs, et nous étudions l'influence de l'épaisseur du CIGSe sur les paramètres photovoltaïques des cellules. Le comportement similaire aux simulations numériques.Une ingénierie du contact avant sur des cellules CIGSe à différentes épaisseurs est réalisée pour spécifiquement améliorer l'absorption dans la couche de CIGSe. Nous étudions l'influence d'une couche tampon alternative de ZnS, de la texturation de la fenêtre avant de ZnO:Al, et d'une couche anti-reflet sur la cellule solaire. D'importantes améliorations sont observées quelque soit l'épaisseur de la couche de CIGSe, ce qui permet d'obtenir des rendements de conversions supérieurs à ceux obtenus dans la configuration standard des dispositifs.Une ingénierie du contact arrière à basse température est également réalisée avec l'utilisation d'un procédé novateur combinant la gravure chimique du CIGSe avec un " lift-off " mécanique de la couche de CIGSe afin de la séparer du substrat de Molybdène. De nouveaux matériaux fortement réflecteur de lumière et précédemment incompatible avec le procédé de croissance du CIGSe sont utilisés comme contact arrière pour des cellules CIGSe ultra-minces. Une étude comparative en fonction de l'épaisseur de CIGSe entre des cellules avec contact arrière réfléchissant en Or (Au) et cellules solaires avec contact arrière standard Mo est effectuée. Le contact Au permet d'augmenter significativement le rendement de conversion des cellules solaires à absorbeur sub-microniques comparé au contact standard Mo avec un rendement de conversion supérieur à 10% obtenu sur une cellule CIGSe de 400 nm (comparé à 7.9% avec Mo).Afin de réduire encore plus l'épaisseur de la couche de CIGSe, jusque 100-200 nm, les modèles numériques montrent qu'il est nécessaire d'utiliser un réflecteur lambertien sur la face arrière de la cellule afin de maximiser l'absorption de la lumière. Un dispositif preuve de concept expérimental est réalisé avec une épaisseur de CIGSe de 200 nm et un réflecteur arrière lambertien, et ce dispositif est caractérisé par spectroscopie de transmission/réflexion. La réponse spectrale est déterminée en combinant des valeurs issues de simulation numérique et la mesure expérimental de l'absorption du dispositif. Nous calculons un courant de court circuit de 26 mA.cm-2 pour ce dispositif avec réflecteur lambertien, bien supérieur à ce qui est calculé pour la même structure sans réflecteur (15 mA.cm-2), et comparable au courant mesuré sur une cellule de référence de 2500 nm (28 mA.cm-2). L'utilisation de réflecteur lambertien pour des cellules CIGSe ultraminces est donc particulièrement adaptée pour maintenir de hauts rendements.
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Leonard, Edouard. "Cellules solaires à base de couches minces de Cu(In,Ga)Se2submicrométrique : optimisation des performances par ingénierie optique et électronique." Nantes, 2013. https://archive.bu.univ-nantes.fr/pollux/show/show?id=3014814e-52a6-4dd5-b332-31bcdede4e05.
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La réduction de l’épaisseur de la couche absorbante dans la technologie des cellules solaires à base de Cu(In,Ga)Se2 (CIGSe) constitue un sujet d’importance en permettant de réduire l’utilisation des matériaux et le temps de dépôt. Ce travail s’intéresse plus particulièrement aux couches de CIGSe déposées par procédé de coévaporation en 3 étapes et montre que la réduction de l’épaisseur de la couche de CIGSe de 1,5 μm à 0,5 μm entraine la dégradation significative des performances des cellules solaires. Une première cause semble liée à la présence de phénomènes de recombinaison qui deviennent significatifs pour les cellules solaires à base de CIGSe submicrométrique. L’étude des mécanismes de recombinaison nous a permis de proposer des solutions permettant de réduire fortement les pertes d’origine électronique et atteindre des rendements de 12,7 % pour une épaisseur de CIGSe de 0,5 μm. La dégradation des performances est également liée à la réduction de l’épaisseur de la couche de CIGSe qui induit une réduction de la quantité de photons absorbés. Afin de compenser ce défaut de capacité d’absorption, une approche basée sur un réflecteur arrière a été développée à partir de l’introduction d’une couche de ZnO:Al entre la couche de molybdène et la couche de CIGSe. Les difficultés rencontrées pour réaliser des cellules solaires à réflecteur sans dégradation des propriétés électriques, nous ont poussés à proposer une approche basée sur la réalisation de contacts électriques ponctuels entre le CIGSe et le molybdène. Les premiers résultats soulignent la pertinence de cette approche qui permet, dans certaines conditions, de réaliser un gain optique tout en conservant des propriétés électriques satisfaisantesThe decrease of absorber thickness in co-evaporated Cu(In,Ga)Se2 based solar cell is important for both material consumption and production cycle time issues. This work proposes an analysis of Cu(In,Ga)Se2 solar cells deposited by multi-source physical vacuum evaporation using 3-stage process with absorber thickness reduced from 1. 5 μm to 0. 5 μm. The present contribution aims at drawing a diagnostic of the origins of the efficiency loss, discriminating optical loss and electrical issues. Electrical loss seems to be due to the formation of unfavourable electrical properties for the thinnest absorbers. The investigation of recombination mechanisms enabled us to propose adapted solutions to avoid electrical loss leading to efficiency of 12. 7 % for 0. 5 μm CIGSe solar cell. Since CIGSe thickness reduction is also responsible for efficiency loss due to a reduced absorption of photons, we introduced a back contact reflector based on a ZnO:Al layer deposited between the molybdenum layer and the CIGSe layer. We proposed an approach based on electrical point contact between the CIGSe layer and the molybdenum layer in order to allow optical gain without electrical losses due to the introduction of ZnO:Al layer. The better performances of solar cells underline the potential of this approach to improve significantly the efficiencies of submicron absorber CIGSe solar cells
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Joel, Jonathan. "Characterization of Al2O3 as CIGS surface passivation layer in high-efficiency CIGS solar cells." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230228.
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In this thesis, a novel method of reducing the rear surface recombination in copper indium gallium (di) selenide (CIGS) thin film solar cells, using atomic layer deposited (ALD) Al2O3, has been evaluated via qualitative opto-electrical characterization. The idea stems from the silicon (Si) industry, where rear surface passivation layers are used to boost the open-circuit voltage and, hence, the cell efficiency. To enable a qualitative assessment of the passivation effect, Al/Al2O3/CIGS metal-oxide-semiconductor (MOS) devices with 3-50 nm oxide thickness, some post-deposition treated (i.e. annealed), have been fabricated. Room temperature capacitance-voltage (CV) measurements on the MOS devices indicated a negative fixed charge density (Qf) within the Al2O3 layer, resulting in a reduced CIGS surface recombination due to field effect passivation. After annealing the Al2O3 passivation layers, the field effect passivation appeared to increase due to a more negative Qf. After annealing have also indications of a lower density of interface traps been seen, possibly due to a stronger or activated chemical passivation. Additionally, the feasibility of using ALD Al2O3 to passivate the surface of CIGS absorber layers has also been demonstrated by room temperature photoluminescence (PL) measurements, where the PL intensity was about 20 times stronger for a structure passivated with 25 nm Al2O3 compared to an unpassivated structure. The strong PL intensity for all passivated devices suggests that both the chemical and field effect passivation were active, also for the passivated as-deposited CIGS absorbers.
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Wang, Yajie [Verfasser], Bernd [Akademischer Betreuer] Szyszka, Rutger [Akademischer Betreuer] Schlatmann, Bernd [Gutachter] Szyszka, Rutger [Gutachter] Schlatmann, and Bart [Gutachter] Vermang. "Investigation of perovskite-CIGSe tandem solar cells / Yajie Wang ; Gutachter: Bernd Szyszka, Rutger Schlatmann, Bart Vermang ; Bernd Szyszka, Rutger Schlatmann." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1187830607/34.
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Rostvall, Fredrik. "Potential Induced Degradation of CIGS Solar Cells." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227745.
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This thesis studies the effects of Na diffusion in Cu(In,Ga)Se2 (CIGS) solar cells,caused by electrical Potential Induced Degradation (PID) and how to prevent it. Thiswas done by subjecting CIGS solar cells a temperature of 850C and an electrical biasfrom the backside of the glass substrate to the Mo back contact of the CIGS cell.When the bias was negative at the back contact the Na diffused in to the CIGS(degradation) and when it was positive the ions diffused out again (recovery). TheCIGS samples were electrically characterized with IV- and EQE-measurements duringthese conditions and compositional depth profiling was used to track the Nadistribution.This study showed that during degradation Na seemed to accumulate in the interfacesbetween the different layers in the CIGS cell. The buffer and window layers arestrongly affected by Na diffusion. Zn(O,S) buffer layer showed a clear difference inrecovery behavior compared to CdS buffer layer. The introduction of an Al2O3barrier layer between the CIGS and Mo back contact increased the degradation timefrom 50 h to 160 h. During this study it was also found that in some cases the CIGSsolar cells efficiency could be improved by degrading the cells and then recoveringthem, in the best case from 13% average energy efficiency to 15% efficiency.
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Cano, Garcia Jose. "Damp Heat Degradation of CIGS Solar Modules." Thesis, Högskolan Dalarna, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:du-26006.
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Due to the short period that some photovoltaic technologies have taken part on the solar energy market, it is crucial to evaluate the long term stability of solar cells belonging to those technologies in order to ensure a minimum lifetime of their performance. Accelerated degradation tests are thus carried out to achieve such goals. The present study analyzes the encapsulation effects on co-evaporated manufactured Copper Indium Gallium Selenide (CIGS) solar cells under damp heat conditions, consisting in 85 °C and 85 % relative humidity, during an approximated period of 1000 hours. The experimental procedure has been carried out at Solliance Solar Research facilities. Since the encapsulation packages play a critical role as a protection to achieve long term stability of the solar cells and modules, several packaging structures and materials has been taken into study. Thus, eighteen types of mini modules were manufactured including different combinations of encapsulants, front sheet foils, thin film protective barriers and CIGS cells from different manufacturers. The design of these mini modules and the manufacturing process to obtain them is also presented in this work. Various characterization techniques were carried out in order to acquire the required information about the solar cells and encapsulants performance along the damp heat degradation process. The results exposed that encapsulation packages including thin film barriers between the encapsulant and the front sheet foil allowed a longer solar cell lifetime due to their remarkable protection against moisture ingress. Moreover, the degradation of the molybdenum layer included in the CIGS cells was found as principal cause of efficiency decrement and end of performance of solar cells protected by regular encapsulant and front sheet foils. Some other findings in relation with the evaluated components are shown along the present study.
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El, Hajje Gilbert. "Développement de nouvelles méthodes de caractérisation optoélectroniques des cellules solaires photovoltaïques par imagerie de luminescence." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066604/document.
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La connaissance approfondie sur la luminescence des dispositifs photovoltaïques (PV) en a fait un outil de caractérisation puissant qui capte l'intérêt de la recherche et des industries du PV. Dans cette thèse, nous nous concentrons sur la luminescence des cellules solaires photovoltaïques à base de Cu(In,Ga)Se2. En particulier, nous explorons et revisitons ses dépendances temporelles, spectrales et spatiales. Cela a abouti dans un premier temps à la mise au point de nouvelles méthodes de caractérisation basée sur la luminescence de cette technologie PV en particulier. Nous montrons d’abord que par l’intermédiaire d'une méthode sans contact toute optique, nous sommes en mesure de détecter et de localiser les métastabilités de cette technologie. En utilisant une approche numérique basée sur des résultats expérimentaux de photoluminescence résolue en temps (TRPL) nous avions réussi à quantifier la densité des défauts de piégeage qui sont derrière ces métastabilités. Une fois quantifiée, nous traduisons cette densité en pertes absolues de performance PV de la cellule solaire. Ensuite, en explorant la dépendance spatiale de la luminescence des cellules solaires à base de Cu(In,Ga)Se2, nous avions corrélé avec succès, ses aspects temporels et spectrales en se basant sur la microscopie confocale à balayage et l’imagerie hyperspectrale. Cela nous a permis de généraliser nos résultats précédents à l'échelle globale des cellules solaires. Cette partie de la thèse nous a aidés à mieux comprendre une des origines fondamentales derrière l’inhomogénéité spatiale de la luminescence de ce type de dispositifs photovoltaïques.La dernière partie de la thèse était essentiellement technique et exploratoire. En particulier, nous introduisons une nouvelle technique optique dans le domaine de la caractérisation des dispositifs PV. Cette technique est dédiée à l’imagerie résolue en temps du temps de vie de fluorescence (TR-FLIM). Le principe de cette technique consiste essentiellement en acquisition d'images de luminescence du dispositif PV qui sont résolues temporellement. Avec ce nouveau dispositif expérimental, nous sommes maintenant en mesure de résoudre spatialement, et en temps réel la dynamique des porteurs de charge d'une technologie photovoltaïque donnée et accéder à ses propriétés électroniques clés. Une première démonstration a été faite sur une cellule solaire à base de GaAs, et pour laquelle nous avions extrait optiquement, la longueur de diffusion, la mobilité et le temps de vie de ses porteurs. De plus, nous avions pu estimer le coefficient de diffusion du matériau et son taux de dopageThe extensive knowledge on the luminescence of photovoltaic (PV) devices has made it a powerful characterization tool that captures the interest of both research and industrial PV communities. In this thesis, we focus on the luminescence of Cu(In,Ga)Se2-based solar PV. In particular, we explore and revisit the luminescence temporal, spectral and spatial dependencies. This resulted in the development of new luminescence-based characterization methods for this particular PV technology. We show initially that by means of an all-optical, contactless methodology, we are able to detect and localize the metastabilities of this technology. Using a numerical approach based on experimental time-resolved photoluminescence (TRPL) we managed to quantify the trapping defects that are behind these metastabilities. Once quantified, we translated it into absolute losses in the PV performance of the solar cell. By exploring the spatial dependence of the luminescence of Cu(In,Ga)Se2 solar cells, we successfully correlated its temporal and spectral aspects based on scanning confocal microscopy and hyperspectral imaging. This allowed us to generalize our previous findings at the global solar cell scale. This part of the thesis helped us better understand one of the fundamental origins behind the spatially inhomogeneous luminescence of Cu(In,Ga)Se2 PV devices. The final part of the thesis was mainly technical and exploratory. In particular, we introduced a new optical technique to the field of PV characterization. It is dedicated to time-resolved fluorescence lifetime imaging (TR-FLIM) which basically consists of acquiring time-resolved luminescence images of the PV device. With this new setup we are now able to spatially resolve, in real-time the charge carrier dynamics of a given PV technology and access its key electronic properties. A first application was made on a GaAs-based solar cell, for which we were able to optically extract the mobility, diffusion length and lifetime of its carriers. Finally, we were also able to estimate the diffusion coefficient of the material and its doping density
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Bachmann, U. Erlich I. Schnurr N. "Possibilities of Multifunctional FACTS Application in the European Electric Power System under Changing Conditions of the Liberalized Electricity Market, CIGRE, 39th CIGRE Session, Paris, 25-30 August, Paper 14-112." Gerhard-Mercator-Universitaet Duisburg, 2003. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-04142003-132349/.
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Competitive markets play a key role in modern industrial In many European countries, politicians set the stage for an open electricity market to facilitate competition with full access to grids. This has led to changes in load-flow patterns in transmission networks. The grid access is accompanied by large power transits even over long distances and unpredictable short-term changes of system conditions.
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Moreau, Antonin. "Propriétés optiques et caractérisation par photoréflectance de cellules solaires à base de couches minces CIGS électrodéposées." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4305.
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Dans le domaine des cellules photovoltaïques à base de couches minces, l'alliage de Cu(In1-x,Gax)Se2 (CIGSe) constitue l'une des filières les plus avancées. Le passage à l'échelle industrielle soulève cependant de nouvelles problématiques. En effet, si le procédé standard de co-évaporation permet d'atteindre des rendements records supérieurs à 20 %, il reste relativement couteux à mettre en place. C'est ainsi que dans un contexte toujours plus compétitif, l'électrodépôt apparait comme une alternative de choix pour diminuer les coûts de production tout en garantissant des rendements compétitifs sur de grandes surfaces. Néamoins, de nombreuses propriétés spécifiques à ce mode de dépôt restent méconnues. En particulier les propriétés optiques à l'origine du photo-courant. Le premier objectif de cette thèse est donc de déterminer les constantes optiques de chaque couche du dispositif par ellipsométrie. Une attention particulière est donnée à la couche absorbante de CIGSe électrodéposée pour laquelle un protocole spécifique est employé. Une seconde partie de la thèse est dédiée à la réalisation d'un outil de caractérisation sans contact : la photoréflectance (PR). La PR va permettre de mesurer avec précision les énergies de transition interbandes d'un semi-conducteur, dont l'énergie de gap. Nous décrivons dans le détail le dispositif expérimental. Une implémentation originale utilisant une double modulation des sources a été développée et permet de réduire le bruit de mesure induit par la rugosité et la diffusion. L'étude de 14 échantillons de CIGS permet finalement de corréler des paramètres opto-électriques issus des caractéristiques courant-tension aux spectres PRRegarding, thin film photovoltaic market, Cu(In1-x,Gax)Se2 (CIGSe) based material is one of the most advanced technologies. Its high absorption coefficient allows it to absorb an important part of the solar spectrum with only two micron thickness. But while moving from fundamental research to the development of batch flow production, issues still remain. If the standard co-evaporation process lead to the best efficiency up to 20 %, high energy consumption is needed. In an increasingly competitive market, electroplating allows to reduce operating cost related to vacuum processes while guaranteeing competitive efficiencies on large scale modules. Nevertheless, due to the specificities of electroplating, new issues occur and some properties may differ from vacuum routes. In particular, optical properties which are responsible for photo-current generation. The first part of this thesis is thus devoted to obtain the optical constants for each layer of the device by spectroscopic ellipsometry. We pay special attention to the electrodeposited CIGSe absorber layer for which a specific method have been used in order to perform measurements on the back side. The second part of this thesis is dedicated to the development of an caracterisation tool : the photoreflectance (PR). The experimental setup is precisely described. An special implementation, using dual modulation technique, increases accuracy by removing luminescence and scattering perturbations. The study of 14 CIGS samples allows finally to correlate opto-electrical parameters from I(V) curves with PR spectra
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Sampathkumar, Manikandan. "Processing of Advanced Two-Stage CIGS Solar Cells." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4938.
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An advancement of the two stage growth recipe for the fabrication of CIGS solar cells was developed. The developed advancement was inconsistent in producing samples of similar stoichiometry. This was a huge barrier for up scaling the process as the behavior of devices would be different due to variation in stoichiometry. Samples with reproducible stoichiometry were obtained once the heating rate of elements, selenium in particular was better understood. This is mainly attributed to the exponential increase of selenium flux after its evaporation temperature. Monitoring the selenium flux was vital in getting constant selenium fluxes. Few changes to the growth recipe were induced to optimize the amount of selenium being used. Depositions were done using constant selenium to metal flux ratio of 5. Elemental tradeoffs were observed as a result of the growth recipe change. These tradeoffs are in favor of the two stage growth recipe. The solar cells were fabricated on a soda lime glass substrate with a molybdenum back contact. Improper sample cleaning and storage were found to affect the deposition outcome of the molybdenum back contact. This also had a cascading effect on the absorber layer. Residual precipitates during deposition of CdS were avoided by increasing the spinner speed which increased the reaction rate. This is attributed to the growth of CdS either by cluster-by-cluster growth or by ion-by-ion growth. SEM, EDS were some important tools used to characterize the devices. EDS in particular, was used extensively at different stages throughout the growth process to ensure that we were heading in the right direction. Current-voltage (I-V) measurements were done to study the solar cell performance under light and dark.
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Boman, Daniel. "Compositional gradients in sputtered thin CIGS photovoltaic films." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355462.
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Cu(In,Ga)Se2 (CIGS) is a semiconductor material and the basis of the promising thin-film photovoltaic technology with the same name. The CIGS film has a typical thickness of 1-2 mm, and solar cells based on CIGS technology has recently reached efficiencies of 23.3%. Ultra-thin CIGS solar cells use sub-micrometer thick films that require significantly less material and can be manufactured in a shorter amount oftime than films with typical thicknesses. With decreasing thickness, both electrical and optical losses get more significant and lower the overall performance. Electrical losses can be decreased by increasing the overall film quality and by utilising a graded bandgap throughout the CIGS layer. The band gap can be changed by varying the[Ga]/([Ga]+[In]) (GGI) ratio. Higher overall film quality and a higher band-gap towards the back of the absorber are expected to increase the performance. In this work, sputtered CIGS solar cells were made with different CIGS layer thicknesses, that ranged between 550-950 nm. Increased heat during deposition was examined and shown to increase the film quality and performance for all thicknesses. Two different ways of doping CIGS with Na was examined and it was found that higher Na content lead to an increasing predominance of the (112) plane. The bandgap was graded by varying the GGI composition throughout the CIGS layer and depth profiles were made with Glow-Discharge Optical Emission Spectroscopy (GDOES). It was found that a sputtered CuGaSe2 (CGS)layer below the CIGS-layer lead to a steep increase of the GGI near the back contact. When CGS made up 10% of the total CIGS layer thickness, a significant increase in performance was observed for all thicknesses. CIGS-absorbers with a less graded region with low GGI, making up 30% or 60% of the total CIGS layer thickness were made. A decrease in GGI in that region, was shown to increase the current but lower the voltage. No substantial increase in total performance compared to a fully graded CIGS layer was seen regardless of layer thickness. For further work the optical losses needs to be addressed and work on increasing the optical path in the CIGS layer needs to be done.
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Nygårds, Emma. "Optimering av CdS-buffertlager för alkalibehandlade CIGS-solceller." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324427.
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An increase in conversion efficiency of CIGS thin film solar cells has been reached at Ångström Solar Center (ÅSC) due to an introduction of a post-deposition-treatment (PDT) with potassium fluoride (KF) on the CIGS absorber layer. The PDT will however affect the growth of the cadmium sulfide (CdS) buffer layer normally deposited on the CIGS layer. The purpose of this study has therefore been to increase the conversion efficiency of the CIGS solar cells by optimizing the process parameters when growing CdS with a chemical bath deposition process (CBD) on CIGS with KF-PDT. The purpose has also been to understand how CdS grows on CIGS with KF-PDT. CdS has been deposited with CBD on both CIGS with KF-PDT and on soda lime glass samples by varying process parameters such as time, bath temperature and concentrations. The solar cells were characterized using current-voltage measurements as well as external quantum efficiency measurements. Further methods of analysis were profilometry, x-ray fluorescence spectroscopy and scanning electron microscopy. It was found that the solar cells with the best performance were obtained at a bath temperature of 70 °C, process time of 3 min after preheating the cadmium acetate and ammonia solutions for 6 min and using the concentrations of the baseline process for CBD of CdS at ÅSC. The best cell of this sample resulted in a conversion efficiency of 19.1 % without antireflective coating.
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Mohanakrishnaswamy, Venkatesh. "Processing and characterization of CIGS - based solar cells." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000368.
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De, Abreu Mafalda Jorge Alexandre. "Advanced rear contact design for CIGS solar cells." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257846.
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The current trend concerning the thinning of solar cell devices is mainly motivated by economic aspects, such as the cost of the used rare-earth elements, and by the requirements of emergent technologies. The introduction of ultra-thin absorber layers results in a reduction of used materials and thus contributes to a more cost-effective and time-efficient production process.However, the use of absorber layers with thicknesses below 500nm gives rise to multiple apprehensions, including concerns regarding light management and the absorber’s quality.Therefore, this experimental work presents a novel solar cell architecture that aims to tackle the issues of optical and electrical losses associated with ultra-thin absorber layers. To that end, a Hafnium Oxide (H f O2) rear side passivation layer was introduced in-between the copper indium gallium (di)selenide Cu(In, Ga)Se2, CIGS-based absorber layer and the Molybdenum (Mo) back contact. Then, the proposed Potassium Fluoride (KF) alkali treatment successfully established point contacts on the ALD-deposited oxide layer, resulting in a passivation effect with minimum current blockage.The established cell architecture showed significant improvements regarding both open circuit voltage (Open-Circuit Voltage (Voc)) and efficiency when compared to unpassivated reference devices. The used solar cell simulator (SCAPS) attributes the observed improvements to a reduced minority carrier recombination velocity at the rear side of the device. Moreover, the provided photoluminescence (PL) results report a higher peak intensity and lifetime for passivated devices.Furthermore, the overlay of the given external quantum efficiency (EQE) spectra with the performed simulations show that the HfO2 passivation layer improves the optical reflection from the rear contact over a wavelength interval ranging from 500 to 1100 nm, resulting in a short circuit current (Jsc) improvement. An increased quantum efficiency observed throughout almost the entire measurement range, confirms that the enhance in Jsc is also due to electronic effects.Here, a produced solar cell device including a 3nm-thick HfO2 rear passivation layer and a 500nm-thick 3-stage CIGS absorber, achieved a conversion efficiency of 9.8%.Further, the approach of combining an innovative rear surface passivation layer with a fluoride-based alkali treatment resulted in the development and successful characterisation of a 1-stage, 8.6% efficient solar cell. Such result, mainly due to a short circuit current (Jsc) enhancement, supports the introduction of more straightforward production steps, which allows a more cost-effective and time-efficient production process. The produced device consisted of a 500nm-thick CIGS absorber, rear passivated with an ultra-thin (2nm) HfO2 layer combined with a 0.6M KF treatment.Den nuvarande trenden när det gäller solcellsanordningar huvudsakligen motiveras av ekonomiska aspekter, såsom kostnaden för att använda sällsynta jordartsmetaller, och av kraven i ny teknik. Införandet av ultratunna absorptionsskikt resulterar i en minskning av använda material och bidrar därmed till en mer kostnadseffektiv och tidseffektiv produktionsprocess.Användningen av absorptionsskikt med tjocklekar under 500 nm ger emellertid upphov till flera bekymmer, beträffande ljushantering och absorptorkvalitet.Därför presenterar detta experimentella arbete en ny solcellarkitektur som syftar till att ta itu med frågorna om optiska och elektriska förluster förknippade med ultratunna absorberlager. För detta ändamål infördes ett Hafnium Oxide (H f O2) bakre sidopassiveringsskikt mellan kopparindiumgallium (di) selenid Cu(In, Ga)Se2, CIGSbaserat absorberande skikt och Molybdenum (Mo) kontakt. Sedan upprättade den föreslagna kaliumfluorid (KF) alkali-behandlingen framgångsrikt punktkontakter på det ALD-avsatta oxidskiktet, vilket resulterade i en passiveringseffekt med minimal strömblockering.Den etablerade cellarkitektur visade signifikanta förbättringar avseende både öppna kretsspänningen (Voc) och effektivitet i jämförelse med opassiverad referensanordningar. Den använda solcellsimulatorn (SCAPS) tillskriver de observerade förbättringarna till en minskad minoritetsbärares rekombinationshastighet på enhetens baksida. Dessutom de tillhandahålls fotoluminescens (PL) resultat rapporterar en högre toppintensitet och livslängd för passive enheter.Dessutom visar överläggningen av det givna externa kvantitetseffektivitetsspektrumet (EQE) med de utförda simuleringarna att passiveringsskiktet HfO2 förbättrar den optiska reflektionen från den bakre kontakten över ett våglängdsintervall från 500 till 1100 nm, vilket resulterar i i en kortslutningsström (Jsc) förbättring. En ökad kvantverkningsgrad observerats i nästan hela mätområdet, bekräftar att öka i Jsc är också på grund av elektroniska effekter.Här, en producerad solcellsanordning innefattande en 3 nm-tjock HfO2 bakre passiveringsskikt och ett 500 nm-tjock 3-stegs CIGS absorber, uppnått en omvandlingseffektivitet på 9.8%.Vidare resulterade tillvägagångssättet att kombinera ett innovativt bakre ytpassiveringsskikt med en fluoridbaserad alkalibehandling i utvecklingen och framgångsrik karaktärisering av en 1-stegs, 8.6% effektivitet solcell. Ett sådant resultat, främst på grund av en kortslutningsström (Jsc) förbättring, stöder införandet av mer enkla produktionssteg, vilket möjliggör en mer kostnadseffektiv och tidseffektiv produktionsprocess. Den framställda anordningen bestod av ett 500 nm-tjock CIGS absorber, bakre passiverad med en ultra-tunn (2 nm) HfO2-skikt kombineras med en 0.6M KF behandling.
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Stanley, Mishael. "Développement de Cellules Photovoltaiques à base de CIGS de haute performance sur substrats métalliques." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEC023.
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L’objectif de cette thèse est l’optimisation de cellules solaires à base de Cu(In,Ga)Se2 (CIGS) sur substrat métallique à très haut rendement (>20%). Les métaux ont généralement une meilleure tenue mécanique que le verre qui est un matériau fragile. Cela permet par exemple de réduire fortement leur épaisseur et d’obtenir des dispositifs photovoltaïques plus légers. De plus, si leur épaisseur est suffisamment réduite, ils deviennent conformables voire flexibles. Cependant, les substrats métalliques ont leurs propres inconvénients. Ils peuvent contenir des impuretés (ex : Fe) qui dégradent les propriétés électroniques du matériau absorbeur. De plus, leur coefficient de dilatation thermique n’est pas toujours adapté aux procédés d’élaboration à haute température du CIGS. Enfin les cellules CIGS déposées sur substrat verre bénéficient d’un apport de sodium, élément connu pour améliorer les propriétés du CIGS, et apporté par la diffusion de cet élément depuis le verre via le molybdène. L’objectif principal de cette thèse consiste à réaliser des cellules solaire à base de CIGS par la technique de coévaporation sur substrats métalliques ayant des performances les plus proches possibles des cellules sur substrats en verre sodocalcique (>20%). Les problématiques auxquelles cette thèse doit répondre sont le choix du substrat métallique, le blocage de la diffusion des impuretés contenues dans les substrats métalliques, l’assurance d’une adhésion forte au substrat, la réduction des contraintes résiduelles (permettant de garantir l’adhésion) et surtout l’optimisation de la couche de Mo adéquate permettant l’apport nécessaire d’élément alcalin (Na/K,…) pour un CIGS de haute performance et l’adaptation de l’absorbeur à ce type de substrat. En effet la qualité du CIGS sera fortement dépendante de la température de dépôt, de l’apport d’élément alcalin provenant du substrat et des gradients de composition In/Ga du contact arrière vers la surface du CIGS. Il est connu qu’il est nécessaire d’avoir un gradient de gallium dans la couche de CIGS afin d’obtenir des cellules à haut. Le dépôt de couches de CIGS par co-évaporation se fera par la méthode du « three-stage process ». Celle-ci consiste à déposer la couche en trois étapes bien définies. Il est important de bien maîtriser ce procédé afin de pouvoir obtenir un absorbeur de qualité pour les cellules solairesThe objective of this thesis is the optimization of solar cells based on Cu (In, Ga) Se 2 (CIGS) on high performance metal substrate (> 20%). Metals generally have better mechanical strength than glass which is a brittle material. This allows for example to significantly reduce their thickness and get lighter photovoltaic devices. Moreover, if their thickness is sufficiently reduced, they become conformable or flexible. However, the metal substrates have their own drawbacks. They may contain impurities (eg Fe) that degrade the electronic properties of the absorber material. Furthermore, their thermal expansion coefficient is not always suitable for methods of making high temperature CIGS. Finally CIGS cells on glass substrate have a sodium intake, known element for improving the properties of the CIGS, and brought by the spread of this element from the glass through the molybdenum. The main objective of this thesis is to make solar cells based on CIGS by co-evaporation technique on metal substrates having the closest possible performance of the cells on substrates of soda lime glass (> 20%). The problems that this thesis must meet are the choice of the metal substrate, blocking the diffusion of impurities in the metallic substrates, ensuring strong adhesion to the substrate, reducing residual stresses (to ensure adherence ) and especially the optimization of the Mo adequate layer allowing necessary intake of alkali metal element (Na / K, ...) for a high performance and adaptation CIGS absorber to this type of substrate. Indeed the quality of CIGS will be highly dependent on the deposition temperature of the intake of alkaline element from the substrate and composition gradients In / Ga the back contact to the surface of CIGS. It is known that it is necessary to have a gradient gallium in the CIGS layer in order to obtain cells high. The deposition of CIGS layers by co-evaporation method will be by the "three-stage process." This involves depositing the layer of three well-defined stages. It is important to control this process in order to get a quality absorber for solar cells
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Reithe, Annegret [Verfasser]. "Charakterisierung verschaltungsbedingter Degradationsmechanismen in flexiblen CIGS-Solarmodulen / Annegret Reithe." Aachen : Shaker, 2015. http://d-nb.info/1071527916/34.
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Ullah, Shafi. "THIN FILM SOLAR CELLS BASED ON COPPER-INDIUMGALIUM SELENIDE (CIGS) MATERIALS DEPOSITED BY ELECTROCHEMICAL TECHNIQUES." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/86290.
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The improvement of low cost, efficient photovoltaic devices is a leading technological challenge in the recent decade. There is a need to develop scalable and high-throughput manufacturing techniques that could reduce costs and improve manufacturing of chalcogenide solar cells. Copper, indium, gallium, and selenium (CIGS) Thin films polycrystalline heterojunction solar cells appear to be most appropriate with to cost and ease of manufacture. Currently Cu (In,Ga) (Se, S)2 materials hold the highest record cell efficiency of 22.3% in laboratory scale for thin films solar cells and the efficiency still be boosted by improving the different layers of the photovoltaic devices. CIGS chalcogenide absorber layers has been a leading candidate material in photovoltaic devices for thin films solar cells and space applications due to its unique optical-electronic properties as well as its radiation resistance. In the present work, thin films of Cu (In, Ga) (Se, S)2 were deposited at room temperature on glass substrates coated with ITO and Mo by electrodeposition techniques. The obtained polycrystalline thin films were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) analysis. Thin films of Cu (In, Ga) (Se, S)2 grown by electrodeposition were subsequently processed into several sets of conditions including vacuum heat treatment, heat treatment in the presence of selenium or sulfur, heat treatment in nitrous gas atmosphere (N2H2) at different temperature and processing times. To improve the composition and the crystalline structure of the thin layers and to optimize the electro-optical properties a heat treatment of the thin films was developed in two stages after the electrodeposition. It was observed that the first annealing step (heating treatment at 450 °C in a selenium atmosphere 40 minutes) produced an appreciable improvement in the crystalline structure in the thin layer composition. In a second stage a sulfurization of the CuGaSe2 films was performed at 400 °C for 10 min in the presence of molecular sulfur and under the forming gas atmosphere. The effect of sulfurization was the complete conversion of selenium to sulfur and, therefore, the transformation of CuGaSe2 into CuGaS2. The formation of CuGaS2 thin films was evidenced by the by the displacement of the diffraction peaks of the CuGaSe2 towards higher angles to which makes the X-Ray diffraction 18 pattern which makes it coincide with the diffraction pattern of the CuGaSe2 films, and by the shift towards the blue (higher energies) of the optical gap. The optical gap found for the CuGaSe2 layer was 1.66 eV, while the optical gap for the CuGaS2 was raised up to 2.2 eV. CdS thin films have been widely used as buffer layer in CIGS solar cells. However, when alloyed with Zn, ZnCdS can still improve its performance as buffer layer. ZnCdS can be used as buffer and as window material in photoconductive devices and in heterojunction thin film solar cells due the possibility to tune the bandgap with the content of Zn. The band spacing of this ternary material can be from 2.42 to 3.50 eV, depending on the Cd/Zn ratio.La obtención de dispositivos fotovoltaicos más eficientes y de bajo coste es uno de los desafíos tecnológicos más importantes de las últimas décadas. Existe la necesidad de desarrollar técnicas de fabricación escalables y de alto rendimiento que puedan reducir los costos y mejorar la fabricación de células solares de capa fina. Las células solares de heterounión de capas finas de seleniuro (o sulfuro) de cobre, indio y galio (CIGS) parecen estar bien adaptadas lograr este reto debido a su bajo costo, facilidad de fabricación y elevado rendimiento de los dispositivos. En la actualidad, Cu(In, Ga)Se2 ostenta el record de eficiencia de células solares con 22,3% a escala de laboratorio y esta eficiencia todavía puede ser acrecentada si se mejoran las diferentes capas de los dispositivos fotovoltaicos. Además, las capas absorbedoras de calcogenuros CIGS son un material candidato importante en dispositivos fotovoltaicos para capas delgadas celdas solares para aplicaciones espaciales debido a sus propiedades electrónicas, así como a su resistencia a la radiación. En el presente trabajo, las películas delgadas de Cu(In, Ga)(Se, S)2 se depositaron a temperatura ambiente sobre sustratos de vidrio recubiertos con ITO y Mo mediante técnicas electroquímicas. Las películas finas policristalinas obtenidas se caracterizaron por espectroscopia óptica UV-Vis, difracción de rayos X (XRD), microscopía electrónica de barrido (SEM), microscopía de fuerza atómica (AFM), microscopía electrónica de transmisión (TEM) y espectroscopia de energía dispersiva (EDS). Las películas finas de Cu(In, Ga)(Se, S)2 crecidas por electrodeposición se procesaron posteriormente en varios conjuntos de condiciones que incluían tratamiento térmico en vacío, tratamiento térmico en presencia de selenio o de azufre, tratamiento térmico en atmósfera gas nidrón (N2H2) a diferentes temperaturas y tiempos de procesado. Para mejorar la composición y la estructura cristalina de las capas finas y para optimizar las propiedades electro-ópticas se desarrolló un tratamiento térmico de las películas finas en dos etapas posterior a la electrodeposición. Se observó que la primera etapa de recocido (tratamiento térmico a 450 ºC en una atmósfera de selenio durante 40 minutos) producía una mejora apreciable en la estructura cristalina y en la composición de la capa fina. 20 En una segunda etapa se realizó una sulfuración de las películas de CuGaSe2 se realizó a 400 °C durante 10 min en presencia de azufre molecular y bajo la atmósfera reductora de gas nidrón. El efecto de la sulfuración fue la completa conversión del selenio en azufre y, por tanto, la transformación de CuGaSe2 en CuGaS2. La formación de películas delgadas de CuGaS2 se evidenció por el desplazamiento de los picos de difracción de las capas de CuGaSe2 hacia ángulos más altos hasta lo que hace que el patrón de difracción de rayos X lo que hace que coincida con el patrón de difracción del CuGaS2 y por el desplazamiento hacia el azul (energías más altas) del gap óptico. El gap óptico encontrado para las capas de CuGaSe2 era de 1,66 eV, mientras que el gap óptico para las capas de CuGaS2 se elevó hasta 2,2 eV. Las películas delgadas de CdS se han utilizado ampliamente como capa tampón en células solares CIGS. Sin embargo, cuando se alea con Zn, para formar el ternario ZnCdS, todavía puede mejorar su rendimiento como capa buffer. ZnCdS puede utilizarse como tampón y como ventana óptica en dispositivos fotoconductores y en células solares de capa fina de heterounión debido a la posibilidad de ajustar el bandgap con el contenido de Zn.
L'obtenció de dispositius fotovoltaics més eficients i més barats és un dels reptes tecnològics més importants de les últimes dècades. Hi ha la necessitat de desenvolupar tècniques de fabricació que siguen escalables i d'alt rendiment i que permeten reduir els costos de fabricació i millorar el rendiment de les cèl·lules solars de capa fina. Les cèl·lules solars de heterounió de capes fines de seleniur (o sulfur) de coure, indi i gal·li (CIGS) semblen estar ben adaptades per assolir aquest repte degut a del seu baix cost, facilitat de fabricació i elevat rendiment dels dispositius. En l'actualitat, el Cu(In, Ga)Se2 ostenta el rècord d'eficiència de cèl·lules solars amb 22,3% a escala de laboratori i aquesta eficiència encara pot ser augmentada si es milloren les característiques de les diferents capes dels dispositius fotovoltaics. Les capes absorbidores de calcogenurs CIGS són un candidat important per dispositius fotovoltaics per a pel·lícules primes en cel·les solars i aplicacions espacialles degut a les seues propietats electròniques així com a la seua resistència a la radiació. En el present treball, les pel·lícules primes de Cu(In, Ga)(Se, S)2 es van dipositar a temperatura ambient sobre substrats de vidre recoberts amb ITO i Mo mitjançant tècniques electroquímiques. Les pel·lícules fines policristal·lines obtingudes es van caracteritzar per espectroscòpia òptica UV-Vis, difracció de raigs X (XRD), microscòpia electrònica de rastreig (SEM), microscòpia de força atòmica (AFM), microscòpia electrònica de transmissió (TEM) i espectroscòpia d'energia dispersiva (EDS). Les pel·lícules fines de Cu(In, Ga)(Se, S)2 crescudes per electrodeposició es van processar posteriorment en diversos conjunts de condicions que incloïen tractament tèrmic en buit, tractament tèrmic en presència de seleni o de sofre, tractament tèrmic en atmosfera reductora de gas nidró (N2H2) a diferents temperatures i temps de processat. Per millorar la composició i l'estructura cristal·lina de les capes fines i per optimitzar les propietats electro-òptiques es va desenvolupar un tractament tèrmic de les pel·lícules fines en dues etapes posterior a la electrodeposició. Es va observar que la primera etapa de recuit (tractament tèrmic a 450 º C en una atmosfera de seleni durant 40 minuts) produïa una millora apreciable en l'estructura cristal·lina i en la composició de la capa fina. 24 En una segona etapa es va dur a terme una sulfuració de les pel·lícules de CuGaSe2 que es va realitzar a 400 °C durant 10 min en presència de sofre molecular i sota l'atmosfera reductora de gas nidró. L'efecte de la sulfuració va ser la completa conversió seleni en sofre i, per tant, la transformació de CuGaSe2 a CuGaS2. La formació de pel·lícules primes de CuGaS2 es va evidenciar pel desplaçament dels pics de difracció de les capes de CuGaSe2 cap angles més alts fins el que fa que el patró de difracció de raigs X el que fa que coincideixi amb el patró de difracció del CuGaS2 i pel desplaçament cap al blau (energies més altes) del gap òptic. El gap òptic trobat per a les capes de CuGaSe2 era de 1,66 eV, mentre que el gap òptic per a les capes de CuGaS2 es va elevar fins a 2,2 eV. Les pel·lícules primes de CdS s'han utilitzat àmpliament com a capa amortidora en cèl·lules solars de CIGS. No obstant això, quan s'alea amb Zn per formar ZnCdS encara pot millorar el seu rendiment com a capa d'amortiment. ZnCdS pot utilitzar-se com capa tampó i com a finestra òptica en dispositius fotoconductors i en cèl·lules solars de pel·lícula fina d'heterounió degut a la possibilitat d'ajustar el seu bandgap que depoen del contingut de Zn.
Ullah, S. (2017). THIN FILM SOLAR CELLS BASED ON COPPER-INDIUMGALIUM SELENIDE (CIGS) MATERIALS DEPOSITED BY ELECTROCHEMICAL TECHNIQUES [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86290
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Painchaud, Thomas. "Mécanismes de croissance des couches minces de Cu (In, GA) Se2 co-évaporées : vers des synthèses rapides et à basse température." Nantes, 2010. http://www.theses.fr/2010NANT2088.
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Une cellule solaire à base de Cu(In1-xGax)Se2 a la structure suivante Verre/Mo/Cu (In1- Gax)Se2/CdS/i-ZnO/ZnO:Al. La synthèse rapide et à basse température des couches minces de CIGSe co-évaporées à haut rendement constituent des enjeux importants pour la filière industrielle CIGSe. Afin de parvenir à ces 2 objectifs, une étude des mécanismes de croissance de l'absorbeur CIGSe a été réalsée via l'utilisation d'un procédé en 3 étapes. Il a été mis en évidence qu'un phénomène de recristallisation opère pour des couches minces de CIGSe (0≤ x ≤0,3) lors de la 2ème étape lorsque la teneur en cuivre est proche de la stoechiométrie, i. E. Y =[Cu]/([In]+[Ga] )≈ 1. Cette recristallisation est thermiquement activée et consiste en une augmentation de la taille des grains qui se traduit par une diminution de la densité de joints de grains. L'interprétation de cette croissance repose sur un modèle basé sur la migration des joints de grains. La compréhension du mécanisme de croissance nous apermis de diminuer le temps de dépôt de la couche mince de 23min (h=16%, FF=76%) à 6min(h=14%, FF=74%) à Tsub=600°C. Au sein du procédé à 3 étapes, la 3ème étape semble limitée cinétiquement. Afin de minimiser la température du substrat, l’impact du contact arrière de Mo au sein du dispositif photovoltaïque a été étudié. La diffusion du sodium du substrat vers le CIGSe à travers le Mo joue un rôle électronique et est influencée par la porosité du molybdène et par Tsub. Ainsi, pour une couche mince de CIGSe déposée sur un substrat à 450°C, une porosité comprise entre 11 et 15% permet d'atteindre des rendements de 13,5% pour des facteurs de forme de 73%Cu(In1-xGax)Se2 solar cells are based on the Mo/Cu(In1-xGax)Se2/CdS/i-ZnO/ZnO:Al structure. Therapid growth of co-evaporated CIGSe thin films at low temperature is an important issue for theindustrial development of CIGSe modules. In order to achieve these 2 targets, CIGSe growthmechanisms during the 3-step process have been investigated. In the present work, a recrystallizationphenomenon has been underlined when the copper content within the CIGSe (0 ≤ x ≤ 0. 3) reaches the stoechiometry, i. E. Y = [Cu]/([In]+[Ga]) ≈ 1. Such a phenomenon is thermally activated and results in the reduction of both the grain boundaries (GB) density and intra-granular defects density. From these observations, a new model based on the grain boundary migration theory is proposed in order to establish a causality relationship between such a composition threshold and the grain boundary motion yielding large grains formation. The understanding of this mechanism allowed the decrease of the deposition time of co-evaporated layers from 23 min (h=16%, FF=76%) to 6 min (h=14%, FF=74%)at Tsub= 600 °C. Within the 3-step process, the homogenous composition of the absorber seemsrestricted by the high speed deposition during the 3rd step. Finally, in order to decrease the substratetemperature, the impact of Mo back contact has been investigated. The sodium diffusion from the glass substrate into CIGSe across the Mo plays an electronical role and is influenced by themolybdenum porosity and Tsub. The experimental optimization of the Mo back contact has allowed the achievement of 13. 5% efficiency with CIGSe absorber synthesized at Tsub = 450°C
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Jahagirdar, Anant. "SOLAR DRIVEN PHOTOELECTROCHEMICAL WATER SPLITTING FOR HYDROGEN GENERATION USING MULTIPLE BANDGAP TANDEM OF CIGS2 PV CELLS AND TH." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3505.
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The main objective of this research was to develop efficient CuIn1-xGaxS2 (CIGS2)/CdS thin film solar cells for photoelectrochemical (PEC) water splitting to produce very pure hydrogen and oxygen. Efficiencies obtained using CIGS2 have been lower than those achieved using CuInSe2 and CuIn1-xGaxSe2. The basic limitation in the efficiencies is attributed to lower open circuit voltages with respect to the bandgap of the material. Presently, the main mechanism used to increase the open circuit voltage of these copper chalcopyrites (CuInSe2 and CuInS2) is the addition of gallium. However, addition of gallium has its own challenges. This research was intended to (i) elucidate the advantages and disadvantages of gallium addition, (ii) provide an alternative technique to the photovoltaic (PV) community to increase the open circuit voltage which is independent of gallium additions, (iii) develop highly efficient CIGS2/CdS thin film solar cells and (iv) provide an alternative material in the form of CIGS2/CdS thin film solar cells and an advanced technology in the form of a multiple bandgap tandem for PEC water splitting. High gallium content was achieved by the incorporation of a highly excess copper composition. Attempts to achieve high gallium content produced reasonable but not the best solar cell performance. Few solar cells developed on a molybdenum back contact and an ITO/MoS2 transparent conducting back contact showed a PV conversion efficiency of 7.93% and 5.97%, respectively. The solar cells developed on the ITO/MoS2 back contact form the first generation CIGS2/CdS thin film solar cells and 5.97% is the first ever reported efficiency on an ITO/MoS2 transparent back contact. Reasons for the moderate performance of these solar cells were attributed to significant porosity and remnants of unsulfurized CuGa alloy in the bulk of CIGS2. This was the first attempt to a detailed study of materials and device characteristics of CIGS2/CdS thin film solar cells prepared starting with a highly excess copper content CIGS2 layer. Next, excess copper composition of 1.4 (equivalent to gallium content, x = 0.3) was chosen with the aim to achieve the best efficiency. The open circuit voltage was enhanced by depositing an intermediate layer of intrinsic ZnO between CdS and ZnO:Al layers. The systematic study of requirements for such a layer and further optimization of its thickness to achieve a higher open circuit voltage (which is the greatest challenge of the scientific community) forms an important scientific contribution of this research. The PV parameters for CIGS2/CdS thin film solar cell as measured officially at the National Renewable Energy Laboratory were: open circuit voltage of 830.5 mV, short circuit current density of 21.88 mA/cm2, fill factor of 69.13% and photovoltaic conversion efficiency of 11.99% which sets a new world record for CIGS2 cells developed using sulfurization and the open circuit voltage of 830.5 mV has become the "Voc champion value". New PEC setups with the RuS2 and Ru0.99Fe0.01S2 photoanodes were developed. RuS2 and Ru0.99Fe0.01S2 photoanodes were more stable in the electrolyte and showed better I-V characteristics than the RuO2 anode earlier used. Using two CIGS2/CdS thin film solar cells, a PEC efficiency of 8.78% was achieved with a RuS2 anode and a platinum cathode. Results of this research constitute a significant advance towards achieving practical feasibility and industrially viability of the technology of PEC hydrogen generation by water splitting.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Malm, Ulf. "Modelling and Degradation Characteristics of Thin-film CIGS Solar Cells." Doctoral thesis, Uppsala University, Solid State Electronics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9291.
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Thin-film solar cells based around the absorber material CuIn1-xGaxSe2 (CIGS) are studied with respect to their stability characteristics, and different ways of modelling device operation are investigated. Two ways of modelling spatial inhomogeneities are detailed, one fully numerical and one hybrid model. In the numerical model, thin-film solar cells with randomized parameter variations are simulated showing how the voltage decreases with increasing material inhomogeneities.
With the hybrid model, an analytical model for the p-n junction action is used as a boundary condition to a numerical model of the steady state electrical conduction in the front contact layers. This also allows for input of inhomogeneous material parameters, but on a macroscopic scale. The simpler approach, compared to the numerical model, enables simulations of complete cells. Effects of material inhomogeneities, shunt defects and grid geometry are simulated.
The stability of CIGS solar cells with varying absorber thickness, varying buffer layer material and CIGS from two different deposition systems are subjected to damp heat treatment. During this accelerated ageing test the cells are monitored using characterization methods including J-V, QE, C-V and J(V)T. The degradation studies show that the typical VOC decrease experienced by CIGS cells subjected to damp heat is most likely an effect in the bulk of the absorber material.
When cells encapsulated with EVA are subjected to the same damp heat treatment, the effect on the voltage is considerably reduced. In this situation the EVA is saturated with moisture, representing a worst case scenario for a module in operation. Consequently, real-life modules will not suffer extensively from the VOC degradation effect, common in unprotected CIGS devices.
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Reyes, Figueroa Pablo. "Deposition and characterization of CIGS layers by multiple deposition techniques." Thesis, Nantes, 2016. http://www.theses.fr/2016NANT4052/document.
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Technologies les plus prometteuses pour suivre le défi de la production d'énergie. La première partie de cette mémoire aborde les absorbeurs de CISe préparés par co-évaporation (3 étapes) et l'effet de l'oxygène (ainsi que le sodium) dans les absorbeurs et des cellules solaires. La température du substrat de 1ère étape la plus élevé (400°C), conduit à un rendement maximal de 12% (Voc=460mV, Jsc=37mA/cm2, FF=78,3%). L’oxydation des couches précurseurs de In2Se3 a montré que les oxydations prolongées ont donnée lieu à faibles rendements de cellules solaires. Les cellules de CISe sans Na ont été fortement dégradées après l’oxydation, avec une baisse de Voc (-72%) et de FF (- 45%). La deuxième partie de la mémoire traite avec la croissance des couches de CISe par un procédé hybride (pulvérisation pyrolyse suivie par coévaporation). La croissance est basée sur un processus de co-évaporation en 3 étapes, mais en remplaçant la couche de 1ère étape avec un couche In2Se3 pyrolysée. Il a été montré qu’une couche de CISe de haute qualité peut être obtenue. L’optimisation des conditions de croissance du procédé hybride (régime du Cu) a permis des dispositifs avec un rendement de 11,1%. Une amélioration peut être atteinte par la diminution de la recombinaison au niveau du contact arrièreIn photovoltaics, the thin film Cu(In,Ga)Se2 (CIGSe) technology is one of the most promising technology to keep up with today’s energy production challenge. The first part of this work address the CISe absorbers films prepared by the 3-stage co-evaporation process. Also, the effect of the oxygen (along with sodium) in the CISe absorbers and solar cells is investigated. The highest 1st-stage substrate temperature (400 C) leads to the highest efficiency of 12% (Voc=460mV, Jsc=37 mA/cm2, FF=78.3%). Oxidation of the In2Se3 precursors films showed that long time exposures resulted in low solar cell parameters. The CISe cells without sodium are degraded after oxidation, with a drop in Voc (-72%) and FF (-45%). The second part of the work deals with the growth of CISe films by a hybrid process which involves two deposition techniques, namely spray pyrolysis and co-evaporation. The process is based on a 3-stage coevaporation process but replacing the 1st-stage film with an In2Se3 spray pyrolyzed film. It was shown that highquality CISe films can be obtained. Optimization of the hybrid process growth conditions (Cu regime) allowed solar cells with efficiencies of 11.1% (Voc=438mV, Jsc=37 mA/cm2, FF=67.5%). Further improvement could be achieved by the decrease of recombination at the back contact
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Motahari, Sara. "Surface Passivation of CIGS Solar Cells by Atomic Layer Deposition." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127430.
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Thin film solar cells, such as Cu(In,Ga)Se2, have a large potential for cost reductions, due to their reduced material consumption. However, the lack in commercial success of thin film solar cells can be explained by lower efficiency compared to wafer-based solar cells. In this work, we have investigated the aluminum oxide as a passivation layer to reduce recombination losses in Cu(In,Ga)Se2 solar cells to increase their efficiency. Aluminum oxides have been deposited using spatial atomic layer deposition. Blistering caused by post-deposition annealing of thick enough alumina layer was suggested to make randomly arranged point contacts to provide an electrical conduction path through the device. Techniques such as current-voltage measurement, photoluminescence and external quantum efficiency were performed to measure the effectiveness of aluminum oxide as a passivation layer. Very high photoluminescence intensity was obtained for alumina layer between Cu(In,Ga)Se2/CdS hetero-junction after a heat treatment, which shows a reduction of defects at the absorber/buffer layers of the device.
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Ong, Zi Xuan. "Transport imaging of multi-junction and CIGS solar cell materials." Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/10665.
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Multi-junction solar cells are an emerging technology that improves the conversion rate of solar energy. Indium Gallium Phosphide (InGaP) is commonly used as the top cell in multi-junction cells grown on Germanium (Ge) or Gallium Arsenide (GaAs) substrates. To design more efficient solar cells using InGaP, it is important to characterize its transport parameters, particularly the minority charge carrier mobility, diffusion length and lifetime as a function of doping and material growth conditions. In this work, transport imaging was performed on a set of InGaP heterostructures (with differing thicknesses, doping levels and minority carrier types) to determine their minority carrier diffusion length. These measurements, together with an independent set of time-resolved photoluminescence (TRPL) lifetime data, were used to calculate the minority carrier mobility values. For the shortest diffusion lengths, experimental limitations were encountered involving the finite carrier generation volume. Simulations were performed to explore the potential of modeling the convolution of diffusion behavior with a finite generation region to address these limitations. Transport imaging was also performed on a set of Copper Indium Gallium Selenide (CIGS) materials. Polycrystalline CIGS represents an alternative to the expensive single-crystal InGaP. These initial experiments identified the challenges of applying transport imaging to polycrystalline materials.
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Söderström, Wilhelm. "Alternative back contact for CIGS solar cells built on sodium-free substrates." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-154004.
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It is widely known that the element sodium plays a vital role in providing highefficiency CIGS solar cells and that when cells are built on sodium free substrates theyneed an alternative (a substitute) sodium source. In this study a molybdenum-sodiumcompound has been deposited, investigated and evaluated as an alternative backcontact layer containing sodium. The compound had a 5 at % sodium concentrationand it was manufactured by an Austrian company called Plansee. The aim of the studywas to create an equivalent back contact in the sense of sodium delivery, conductivityand adhesion compared to a normal molybdenum back contact on a soda lime glass. The experimental part of the study started with the construction of complete cells,which were fabricated and measured. This work took place at the ÅngströmLaboratory, Uppsala University, Sweden. The characteristics of the layer and the cellswere analyzed by current voltage measurements, quantum efficiency measurementsand secondary ion mass spectrometry analysis. Cell manufacturing involved sputtering,co evaporation and chemical deposition processes. Results show that the molybdenum-sodium compound increases the efficiency of acell built on a sodium-free substrate. Efficiencies reached 8 % for cells without sodiumin the molybdenum and these cells produced 67 % efficiency and 80 % open circuitvoltage of the reference value. Cells with sodium in the back contact layer produced90 % of the efficiency and 95% of the open circuit voltage relative to the references.The best cell with the molybdenum-sodium compound reached an efficiency of 13.3%. This implies that the new back contact layer acts as a sodium source but the cellshave 1-2 % lower efficiency than the reference cells built on soda lime glass. Othercharacteristics of the layer as conductivity and adhesion show no significant differenceto an ordinary molybdenum back contact. Measurements also indicate that the sodium is probably located inside themolybdenum grains and just a small amount is found at the boundaries and in betweenthe grains. Sodium inside the molybdenum grains is difficult to extract and thereforenot enough sodium will diffuse into the CIGS layer. The conclusions drawn from this study are that the molybdenum-sodium compoundhelps to increase the efficiency of a CIGS solar cell built on a sodium-free substrate,but it does not deliver enough sodium to constitute a substitute sodium source.
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Åsberg, Anders. "Deposition of CIGS absorber layer by gas flow sputtering : Initiation of project." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208140.
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The photovoltaic solar cell industry is growing rapidly, but high cost per watt is still an obstacle. Thin film solar cells, especially thin film solar cells using CIGS absorbers that have the highest proven efficiency, have the potential to reduce the cost through cheap manufacturing. Academic research concerning CIGS solar cells has so far been focused on cells with absorber layers deposited by co-evaporation, which can be used to make very high efficiency cells but is a deposition process ill suited for large scale production. In this thesis a process for depositing CIGS absorber layers by gas flow sputtering, a deposition technique enabling high rate depositions of low energy particles that is potentially easier to apply to a large scale production, has been outlined. Equipment for CIGS-deposition by gas flow sputtering has been prepared, characteristics of the process have been investigated and ultimately a series of first prototype CIGS absorber layers has been deposited as part of complete solar cells. A lot of focus in this thesis is on the practical work and problem solving around the equipment, e.g. pulsed DC power supplies and electrical connections, heating and heating control in a reactive vacuum environment, and on the basic functionality of the gas flow sputter, how process and film properties like deposition rate, thickness uniformity etc. vary with sputter conditions like pressure, gas flow etc. Following the process design the first prototype series produced crystalline CIGS absorbers of desired elemental composition and thickness but having rather small grain sizes, while the complete cells exhibited solar cell IV-characteristics but very poor efficiencies.
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Wu, Tzung-Shin, and 吳宗欣. "Thermal effect on elemental diffusion of ZnO/CdS/CIGSSe solar cell at/near the heterojunction interface." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/cp6w92.
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碩士國立交通大學
工學院加速器光源科技與應用碩士學位學程
102
This study is focused on understanding the elemental diffusion behaviors of Cu(In,Ga)(Se,S)2-based solar cells under the long-term thermal effect, To approach a real situation in application of solar cell, the sample was annealed to 110 oC and maintained this temperature for about 40 hr in the quartz tube. We chemically etched the ZnO/CdS/CIGSSe sample with a gradient thickness to observe the elemental distribution near/at the interfaces, the chemical environments and the electronic structure of the samples were also studied by means of soft and hard X-ray photoemission spectroscopies (XPS). Our results indicate that, the cadmium elements of the buffer layer diffuse into CIGSSe absorber layer, whereas the sulfur diffuses towards the absorber layer. On the other hand, the selenium elements of CIGSSe layer tend to diffuse towards both the buffer and the absorber layers, but Ga, In, and Cu diffuse towards the buffer layer. After thermal treatment, the In 4d photoelectron spectra reveal a lower binding energy component, which can be assigned to the interface phase CdxInySzSe1-z with the unbound valence electron of In. This compound is possibly formed at the interface of CdS and surface In-rich CIGSSe due to interdiffusion of elements. The creation of the unbound electron of In at the CdS/CIGSSe interface will trap the positive carriers, leading to lower probability of carrier collection by the back-side electrode. The redistributed concentration of all elements also leads to a smaller band gap. These results indicate some important factors of degradation in solar-cell conversion efficiency due to thermal effect.
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Chen, Chih Zui, and 陳致睿. "Depth Profiling Electronic Properties of CIGSSe-based Thin Film Solar Cell with Zn(O,S) Buffer Layer." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/44712385357225192516.
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HONG, CHEN-WEI, and 洪晨幃. "The effects of depth profiling and band Structure of CIGSSe solar cell elements to efficiency by using Scanning Photoelectron Microscopy." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/31702554937341469224.
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碩士大同大學
光電工程研究所
103
In this study, we investigated the depth-dependent compositions and band structure of Cu(In,Ga)(Se,S)2-based solar cell device. In order to measure the elemental composition distribution and the band structure of the multi-layered films, we polished the CIGSSe-based solar cell with a gradient thickness to probe the position (depth)-dependent variations in photoelectron signals by using scanning photoelectron microscopy (SPEM). SPEM enables us to directly “observe” the depth-dependent compositions and band structure of the thickness-gradient CIGSSe-based solar cell due to its high spatial resolution (~200 nm) in photoelectron emission. Our experimental results show that the band structure is a spike type at the interface of CdS/CIGSSe. It is also found that the concentration ratios of Ga/In+Ga and S/S+Se are higher at the interface of CdS/CIGSSe, leading to a larger band gap and a higher conduction-band minimum near the top of absorber layer. In addition, we compared the material characteristics with the other sample of lower efficiency. The reason of lower efficiency can be attributed to the conduction band offset at its interface of CdS/CIGSSe, which is larger than the sample in this study.
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Ho, Wei Hao, and 何偉豪. "Investigation of Cd-free buffer layers for CIGSe thin film solar cells." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2zyez7.
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博士國立清華大學
材料科學工程學系
105
Cd-free buffer/CIGSe heterojunction solar cells have attracted much attention due to their non-toxicity and potential to enhance the photovoltaic performance. However, the heterointerface may contain a high density of defects, including the vacancies, antisites and defect complexes, leading the severe interface recombination, metastability behavior and the energy barrier blocking carrier transport, lowering the energy conversion efficiency. This dissertation aims to ameliorate the Cd-free buffer/CIGSe heterojunction properties and improves the device performance. We point out the main challenges in designing the heterojunction and propose three approaches to resolving these issues: In the first part, we demonstrate an effective room-temperature chemical solution treatment, by using thioacetamide (S treatment) or thioacetamide-InCl3 (In-S treatment) solution, on CIGSe surface to engineer the ZnS(O,OH)/CIGSe heterojunction. With treatments, the absolute average efficiency is significantly enhanced over 2 %, and the metastability, in terms of light soaking time, is minimized by 48%. The influences of chemical treatments on defect passivation at the interface are studied carefully. In the second part, we propose a novel approach to ameliorate the sputtered Inx(O,S)y/selenized CIGSe heterojunction, in terms of band alignment and interface properties. The band alignment was tailored by tuning the base pressure of the sputtering process to incorporate oxygen into deposited In2S3 layers. The interface properties were ameliorated by optimizing the air-annealing temperature on Inx(O,S)y /CIGSe stacked layers. Our approach enables the average efficiency improved from 2.30 % to 10.93 %. The mechanisms responsible for the improvements are investigated. In the third part, we successfully develop a full sputtered Inx(O,S)y/CIGSe solar cell technology, and investigate the impacts of Na and Se doping on the defect mechanism and device performance. As the Na-doped CIGSe absorbers buffered with Inx(O,S)y layer, the (VSe-VCu) deep acceptor defects were induced, acting as a transport barrier (p+ layer) at interface, decreasing the FF and JSC. By Se-doping, the (VSe-VCu) deep defects could be eliminated, improving the average efficiency to 11.13 %. We also proposed an approach to reducing the (VSe-VCu) defects in Na-doped CIGSe device. By increasing the Cu content and reducing the amount of Na doping, the average efficiency of the corresponding device could be improved from 4.64 % to 9.04 %.
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Cheng, Hung-Lung, and 程宏隆. "Effects of Sulfur Profiles on Performance of Sulfurized CIGSS Solar Cells Studied by Device Simulation." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/92367936579686798879.
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博士國立東華大學
電機工程學系
103
A device model of thin-film Cu(In,Ga)(Se,S)2 (CIGSS) solar cells with a device structure of SLG/Mo/CIGSS/CdS/i-ZnO/AZO was developed, where the absorbers prepared by the sulfurization after selenization (SAS) method were incorporated in the model. The Cd-doping effect arising from chemical bath deposition process and the inverted conductivity type of surface region of CIGSS thin films due to Cu-poor composition to form the buried p-n homojunction were taken into account. In addition, the interface with interface states of recombination centers between CIGSS and CdS films was introduced into the model. The impacts of specified sulfur profiles for CIGSS absorbers with the different gallium distributions based on selenization of metal alloy on the performance of CIGSS solar cells were evaluated by numerical simulations. The effects of the front grading resulting from the surface sulfurization of CIGSS films were investigated and compared with those resulting from the change of Ga/(Ga+In) ratios. In order to reach the optimal device performance, the impacts of the sulfur distribution within the CIGSS absorbers prepared by SAS method were investigated. Furthermore, the range of O/(O+S) ratios of Zn(O,S) buffers for the improvement of CIGSS performance was studied by numerical simulation. The simulated results suggested that the modest front grading resulting from Ga or S could enhance the performance of devices. A proper sulphur profile could further improve the performance of CIGSS solar cells. The impacts of the incorporation of sulfur into the CIGSS films on the performance of devices were strongly correlated with the gallium distribution inside the CIGSS films. Moreover, the short-circuit current density of CIGSS could be enhanced by using wide-gap Zn(O,S) buffer layers.
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Zhu, Xiaobo, and 朱曉波. "CIGS TFT and inhomogeneity effects on CIGS solar cells." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/13757512392852824787.
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博士國立臺灣大學
電子工程學研究所
104
Cu(Ga, In)Se2 (CIGS) thin film transistors and the inhomogeneity effects on CIGS solar modules are investigated. CIGS is one of the best candidate materials for thin film solar cell due to its strong light absorption as well as its relatively high mobility. It also has the advantage to reduce production cost for photovoltaics devices, and nowadays, the fabrication of CIGS solar cell is mature and commercial. But some problems like uniformity, morphology, and yield still affect the quality of CIGS solar cell and reduce its market in the competition with other kinds of solar cell like Si based solar cell, CdTe solar cell and CZTS solar cell. Besides the application in thin film solar cell, CIGS also has the potential to have a role in other fields, like light sensor, telecommunication, and thin film transistor (TFT). By solving the problems occurred in the fabrication of CIGS solar cell and achieving its application in other fields will promote the value of CIGS. In the first part of this dissertation, CIGS TFT is investigated. The fabricated CIGS TFT achieves a saturation mobility of ~1.8 cm2/V-s, and the on-off ratio over 3 orders of magnitude for the first time. We use a special ring pattern to simplify the fabrication process and avoided the problems occurred in the traditional TFTs. In the structure of CIGS TFT, Al2O3 is deposited by atomic layer deposition (ALD) on CIGS film as the dielectric layer. With the help of Al2O3 layer, the on current is high due to its high dielectric constant, and moreover, the channel can be passivated by Al2O3 layer, so that defects on the interface of CIGS/Al2O3 decrease, and eventually increase the saturation mobility. We also have applied thin-down process on the CIGS thin film, which was prepared for solar cell fabrication, to meet the required conditions for CIGS TFT. The characteristics of CIGS TFT are investigated consequently, and the improvement of saturation mobility after thin down process is found. This might be due to the different qualities of different layers in CIGS thin film, and is justified by the measurements of photoluminescence (PL) and X-ray diffraction (XRD). Moreover, the performances of CIGS TFTs with different content in CIGS films are investigated. TFT with high Cu/(Ga+In) ratio tends to have both high carrier concentration and saturation mobility. Sodium atoms might play important roles in these properties. In the second part of this dissertation, the inhomogeneity effects on CIGS solar modules are investigated. We firstly demonstrate the impact of residual strain on the CIGS solar module with Ga content fluctuation using first principle calculations. The simulation results show that the inhomogeneity effect is magnified by residual strain due to the enhanced band gap fluctuations. Then the 3D simulation results of CIGS solar cells are obtained with the residual strain effect incorporated. The parameters used in the model for the simulation are the same to those used in the commercial CIGS solar cell. A module consists of 3 cells in series, while each cell is divided into 3 sections. Intracell inhomo, intercell inhomo, and combined intracell+intercell inhomo are considered within a module, and the effects of both Ga content and thickness fluctuation are investigated. Among these three distributions, intracell+intercell inhomo is closest to the real distribution of inhomogeneity in the fabrication of CIGS solar module. In reality, Ga content fluctuation is serious and thickness fluctuation can be well controlled. The simulation results show that in terms of Ga content fluctuation, Intracell fluctuation causes VOC degradation, and intercell fluctuation causes JSC and fill factor degradations, and in terms of thickness fluctuation, VOC remains the same due to the constant Ga content, JSC is degraded due to the increase of excess carrier recombination, and the tendency of fill factor degradation is similar to Ga content fluctuation.
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Santos, Jorge Miguel Gonçalves Ferreira dos. "Avaliação da qualidade do posicionamento da rede GNSS SERVIR - CIGeoE." Master's thesis, 2015. http://hdl.handle.net/10451/20740.
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Tese de mestrado, Engenharia Geográfica, Universidade de Lisboa, Faculdade de Ciências, 2015Em 2006 o atual Centro de Informação Geoespacial do Exército (CIGeoE) começou a planear a instalação de uma rede de estações de referência GNSS (SERVIR). Inicialmente as estações estavam localizadas apenas na região de Lisboa, mas atualmente a cobertura integral de Portugal Continental está garantida. Desde a instalação da primeira estação de referência, nunca foi efetuado um controlo de qualidade a toda a rede. Para além deste aspeto, encontra-se em fase de testes, para posterior implementação, um novo programa de cálculo, denominado de Trimble® PIVOT™ (PIVOT), que substituirá o anterior, denominado de GPSNet™ (GPSNET). A realização desta dissertação, nesta fase, acaba por ser de grande importância devido à conjuntura atual já descrita. Para a avaliação geral da qualidade da rede SERVIR, foi seguida uma metodologia que se dividiu em 5 fases fundamentais. Na primeira escolheram-se 49 pontos, dispersos pelo território nacional, materializados por vértices geodésicos (VG) da rede geodésica nacional. De seguida foram selecionados 4 métodos de posicionamento, Estático, Rápido Estático e RTK (em duas variantes) para obtenção das coordenadas tridimensionais dos VG anteriores selecionados. A terceira fase consistiu na determinação das coordenadas a utilizar como referência, para avaliação da exatidão posicional. Na quarta fase foram determinadas as coordenadas de todos os VG, sendo que depois na quinta fase se procedeu à comparação. Os resultados apresentados referem-se a coordenadas cartesianas e geodésicas. Para ambos os tipos de coordenadas e utilizando qualquer dos programas, a rede SERVIR garante uma precisão melhor que 0.045 m, 0.024 m e 0.059 m para as coordenadas X, Y e Z respetivamente. O método RTK, nas suas duas variantes, garante uma exatidão melhor que 0.069 m, 0.062 m e 0.097 m para as coordenadas cartesianas X,Y e Z, ao passo que os resultados foram melhores que 0.055 m, 0.063 m e 0.106 m para a latitude, longitude e altitude, respetivamente. Por fim, a exatidão obtida com o método rápido estático foi melhor que 0.045 m, 0.030 m e 0.037 m, no que diz respeito às coordenadas cartesianas, e foi melhor que 0.024 m, 0.038 m e 0.080 m, no que diz respeito às coordenadas geodésicas.
In 2006 the current Centro de Informação Geoespacial do Exército (CIGeoE) started the installation of a network of GNSS reference stations (SERVIR). Initially the stations were located only in the Lisbon region, but a full coverage of Portugal mainland is assured nowadays. Since the installation of the first reference station, a quality control for the whole network was never carried out. Moreover, a new software package - Trimble Pivot ™ (PIVOT) - is being tested for further implementation, , in replacement of an older one - GPSNet ™ (GPSNET). For these reasons, an evaluation of the quality of SERVIR turns out to be of great importance. For evaluating the overall quality of the SERVIR network, a methodology divided into five key phases was adopted. The first phase consisted in the selection of 49 points, scattered throughout the country and materialized by geodetic monuments (VG) of the national geodetic network. In the second phase, we selected 4 positioning methods, Static, rapid static and RTK (in two variants) to obtain the three-dimensional coordinates of those VG. The third phase consisted in the determination of the coordinates to be used as benchmark, for evaluation of positional accuracy. In the fourth phase, the coordinates of all VG were determined. In the fifth stage, the coordinates computed in the fourth phase were compared against the benchmark values, using both Cartesian coordinates and geodetic coordinates. For both types of coordinates and using any of the software packages, the SERVIR network yields an accuracy better than 0.045 m, 0.024 m e 0.059 m, for the geodetic coordinates (latitude, longitude, altitude). The RTK method, both variants analyzed, yields an accuracy better than 0.069 m, 0.062 m e 0.097 m for the Cartesian coordinates (X, Y, Z), and better than 0.055 m, 0.063 m e 0.106 m, for latitude, longitude and altitude, respectively. Finally the accuracy obtained with the rapid static method was better than 0.045 m, 0.030 m e 0.037 m, for the Cartesian coordinates, and better than 0.024 m, 0.038 m e 0.080 m, for the geodetic coordinates.
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Chang, Chien-wei, and 張謙維. "Preparation and Analyses of CIGSe Thin Films Solar Cells with the Ink-Printing p-Type Absorption Layer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/4cawdx.
Full textAbstract:
碩士國立臺灣科技大學
材料科學與工程系
99
The non-vacuum processes for Cu(In,Ga)Se2(CIGSe) solar cells have gradually attracted the researchers’ attentions. However, the major problem of the non-vacuum processes is the densification and the purity of the p-type absorption layer. In this study, CIGSe thin film solar cells were prepared by using ink-printing on alumina substrates. The p-type layers with the composition of Cu0.8In0.7Ga0.3Se2 were prepared from the inks containing the single-phase CIGSe powder, the mixed powder of Cu2Se, In2Se3, and Ga2Se3, and the mixture of single-phase powder and the mixed powder at the weight ratio of 50:50. The densification involves the one-step and two-step processes at different sintering temperatures. Some of the specimens were underwent the constrained sintering. The CIGSe solar cell was constituted with the stacking form of Ag/ITO/ZnO/CdS/ink-printing CIGSe/Mo/Al2O3. The quality of the absorption layer was analyzed by X-ray diffractometer and field emission of scanning electron microscope equipped with energy dispersive X-ray spectrometer. The performance of the solar cells was evaluated under the standard AM1.5 illumination. The experimental results showed that the best condition for the ink-printing CIGSe thin film with a thickness of 5 um was using the two-step process and the single-phase powder, sintering at 700–750 oC, and undergoing constrained sintering. The CIGSe films had the desired composition, good crystallinity, and the grain size of 600–700 nm. The stacked solar cells displayed the power conversion efficiencies of 1.1% and 1.5% for the cells with the CIGSe layers prepared from the 50/50 powder and the single-phase powder.