[ES] Este proyecto de investigación se centra en el campo de las energías renovables y más concretamente de la energía solar fotovoltaica. La tesis se ha focalizado en el desarrollo de películas delgadas de Cobre-Indio-GalioSelenio o Sulfuro (CuIn1-xGax(Se,S)2) con técnicas de bajo coste. La mayoría de las celdas basadas en CIGS utilizan el CdS como capa de búfer. En nuestro experimento, usaremos otra capa de tampón como SnS2 o ZnO1-xSx como alternativa a CdS para mejorar nuestra célula. El estudio se centrará en el contacto tampón/absorbedor para reducir la recombinación. En este trabajo, reportamos la investigación experimental del desarrollo y desarrollo de la caracterización de la calcopirita de cobre, indio, galio y selenio (CIGS) por la técnica de electrodeposición y pulverización. Además, nos hemos centrado en el contacto entre la capa generadora que es el absorbedor y el circuito externo. Las propiedades eléctricas de este contacto dependen principalmente del proceso de deposición de la capa absorbente en el contacto trasero utilizado. Por lo tanto, será necesario controlar el crecimiento de la capa interfacial de MoSe2 entre el absorbedor y el contacto posterior en el caso del molibdeno para obtener un rendimiento óptimo. Por supuesto, la eficiencia de la célula depende de un gran número de parámetros experimentales y varía según los métodos de fabricación, especialmente la capa absorbente CIGS. En nuestro caso, las técnicas utilizadas son la galvanoplastia y la pirólisis por pulverización para la deposición de películas CIGS. Estas técnicas son más baratas, prácticamente alcanzables en cualquier laboratorio y dan un buen rendimiento. Por lo tanto, mediante técnicas de deposición de bajo coste hemos estudiado el comportamiento de la célula solar con una capa de MoSe2 como capa interfacial y el efecto de la banda prohibida de la capa formada y la capa tampón utilizada sobre los parámetros de las células solares CIGS. Los resultados de este estudio podrían ayudar a mejorar el rendimiento de las células solares CIGS utilizando técnicas de bajo coste. / [CA] Aquest projecte de recerca es centra en el camp de les energies renovables i més concretament en l'energia solar fotovoltaica. La tesi s'ha centrat en el desenvolupament de pel·lícules primes de Coure-Indi-Gali-Seleni o Sulfur (CuIn1-xGax(Se,S)2) amb tècniques de baix cost. La majoria de les cel·les basades en CIGS utilitzen el CdS com a capa de búfer. En el nostre experiment, farem servir una altra capa de tampó com ara SnS2 o ZnO1-xSx com a alternativa al CdS per millorar la nostra cel·la. L'estudi es centrarà en el contacte tampó/absorbidor per reduir la recombinació. En aquest treball, reportem la recerca experimental del desenvolupament i la caracterització de la calcopirita de coure, indi, gali i seleni (CIGS) mitjançant la tècnica d'electrodeposició i pulverització. A més, ens hem centrat en el contacte entre la capa generadora que és l'absorbidor i el circuit extern. Les propietats elèctriques d'aquest contacte depenen principalment del procés de deposició de la capa absorbent en el contacte posterior utilitzat. Per tant, serà necessari controlar el creixement de la capa interfacial de MoSe2 entre l'absorbidor i el contacte posterior en el cas del molibdè per obtenir un rendiment òptim. És clar que l'eficiència de la cel·la depèn d'un gran nombre de paràmetres experimentals i varia segons els mètodes de fabricació, especialment la capa absorbent CIGS. En el nostre cas, les tècniques utilitzades són la galvanoplàstia i la piròlisi per pulverització per a la deposició de pel·lícules CIGS. Aquestes tècniques són més econòmiques, pràcticament assolibles en qualsevol laboratori i proporcionen un bon rendiment. Per tant, mitjançant tècniques de deposició de baix cost hem estudiat el comportament de la cel·la solar amb una capa de MoSe2 com a capa interfacial i l'efecte de la banda prohibida de la capa formada i la capa tampó utilitzada sobre els paràmetres de les cel·les solars CIGS. Els resultats d'aquest estudi podrien ajudar a millorar el rendiment de les cel·les solars CIGS utilitzant tècniques de baix cost. / [EN] Our research project aims at the field of renewable energies and more specifically, photovoltaic solar energy, i.e. solar cells, our study focuses on the elaboration of Copper-Indium-Gallium-Selenium or Sulfide (CuIn1-xGax(Se,S)2 thin films for solar cells with low-cost techniques also to develop the performance of the typical solar cell structure: n-ZnO/i-ZnO/n-tampon/p-CIGS/p+-MoSe2/back contact. Most of the CIGS based cells use CdS as a buffer layer. In our experiment, we will make use of another buffer layer such as SnS2 or ZnO1-xSx as an alternative to CdS to improve our cell. The investigation will be carried out on the buffer/absorber contact to reduce recombination. In addition, we will focus on the contact between the generating layer which is the absorber and the external circuit. The electrical properties of this contact depend essentially on the deposition process of the absorber layer on the back contact used. It will thus be necessary to control the growth of the MoSe2 interfacial layer between the absorber and the back contact in the case of Molybdenum in order to obtain an optimal yield. Obviously, the yield of the cell depends on a large number of experimental parameters and varies according to the fabrication methods, especially of the CIGS absorber layer. In our case the techniques used are electrodeposition and spray pyrolysis for the deposition of CIGS films, there techniques are cheaper, practically feasible in the laboratory and give good performance. Therefore, we will investigate, using low-cost deposition techniques, the performance of the cell with a MoSe2 layer as an interfacial layer and the effect of the bandgap of the formed layer and the buffer layer used on the parameters of the CIGS solar cells. The results of this study could help to improve the performance of the CIGS solar cell using low-cost techniques. / Armel Ignace, N. (2024). Elaboration et caractérisation de couches minces de cuivre, indium, gallium et sélénium (CIGS) pour cellules solaires [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203613

Thin film copper, indium, gallium, selenide (CIGS) solar cells are promising in the field of photovoltaic technology. To reduce material and fabrication cost, as well as increasing electrical properties of the cell, research is ongoing towards ultra-thin film solar cells (absorption layer thickness less than 500 nm). Ultra-thin CIGS solar cells has shown a decrease in interface recombination and improved optical properties when adding a rear contact passivation layer of aluminium oxide. In this work, the process of creating sub-micrometer features of a passivation layer using conventional optical lithography is investigated. To specify, the objective was to optimize the development conditions in the optical lithography process when fabricating equidistant line contacts in aluminium oxide with 800 nm feature size. It was found that line contacts with smaller feature sizes require longer development time, than line contacts with larger feature sizes. The experiments conducted showed that the pre-set development and exposure conditions used by the NOA group are not optimized for 800 nm or smaller line contacts. Further, for the optical lithography process, silicon substrates are not comparable with substrates of soda lime glass coated with molybdenum. Slight underdevelopment of a sample, showed line contacts smaller than the resolution of the laser used in the exposure – suggesting an alternative method of processing small line contacts with optical lithography.

A deeper understanding of Cu(In,Ga)Se2 (CIGS) solar cells is important for the further improvement of these devices. This thesis is focused on the use of electrical modelling as a tool for pursuing this aim. Finished devices and individual layers are characterized and the acquired data are used as input in the simulations. Band gap gradients are accounted for when modelling the devices. The thesis is divided into two main parts. One part that treats the influence of cadmium free buffer layers, mainly atomic layer deposited (Zn,Mg)O, on devices and another part in which the result of CIGS absorber layer modifications is studied. Recombination analysis indicates that interface recombination is limitting the open circuit voltage (Voc) in cells with ZnO buffer layers. This recombination path becomes less important when magnesium is introduced into the ZnO giving a positive conduction band offset (CBO) towards the CIGS absorber layer. Light induced persistent photoconductivity (PPC) is demonstrated in (Zn,Mg)O thin films. Device modelling shows that the measured PPC, coupled with a high density of acceptors in the buffer-absorber interface region, can explain light induced metastable efficiency improvement in CIGS solar cells with (Zn,Mg)O buffer layers. It is shown that a thin indium rich layer closest to the buffer does not give any significant impact on the performance of devices dominated by recombination in the CIGS layer. In our cells with CdS buffer the diffusion length in the CIGS layer is the main limitting factor. A thinner CIGS layer improves Voc by reducing recombination. However, for thin enough absorber layers Voc deteriorates due to recombination at the back contact. Interface recombination is a problem in thin devices with Zn(O,S) buffer layers. This recombination path is overshadowed in cells of standard thickness by recombination in the CIGS bulk. Thin cells with Zn(O,S) buffer layers have a higher efficiency than CdS cells with the same absorber thickness.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 204 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The goal of this research project was to contribute to the understanding of CuGaSe2/CdS photovoltaic devices, and to improve the performance of these devices. The initial part of the research dealt with the optimization of a Sequential Deposition process for CuIn(Ga)Se2 absorber formation. As an extension of this, a recipe (Type I Process) for CuGaSe2 absorber layer fabrication was developed, and the deposition parameters were optimized. Electrical characterization of the thin films and completed devices was carried out using techniques such as Two-Probe and Three-Probe Current-Voltage, Capacitance-Frequency, Capacitance-Voltage, and Spectral Response measurements. Structural/chemical characterization was done using XRD and EDS analysis. Current densities of up to 15.2 mA/cm2, and Fill Factors of up to 58% were obtained using the Type I CuGaSe2 Process. VOC's, however, were limited to less than 700 mV. / ABSTRACT: Several process variations, such as changes in the rate/order/temperature of depositions and changes in the thickness of layers, resulted in little improvement. With the aim of breaking through this VOC performance ceiling, a new absorber recipe (Type II Process) was developed. VOC's of up to 735 mV without annealing, and those of up to 775 mV after annealing, were observed. Fill Factors were comparable to those obtained with Type I Process, whereas the Current Densities were found to be reduced (typically, 10-12 mA/cm2, with the best value of 12.6 mA/cm2). This performance of Type II devices was correlated to a better intermixing of the elements during the absorber formation. To gain an understanding of the performance limitations, two simulation techniques, viz. SCAPS and AMPS, were used to model our devices. / ABSTRACT: Several processing experiments and SCAPS modeling indicate that a defective interface between CuGaSe2 and CdS, and perhaps a defective absorber layer, are the cause of the VOC limitation. AMPS simulation studies, on the other hand, suggest that the back contact is limiting the performance. Attempts to change the physical back contact, by changes in the absorber processing, were unsuccessful. Processing experiments and simulations also suggest that the CuGaSe2/CdS solar cell involves a true heterojunction between these two layers. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Solar irradiation is a vast and plentiful source of energy. The use of photovoltaic (PV) devices to convert solar energy directly to electrical energy is an elegant way of sustainable power generation which can be distributed or in large PV plants based on the need. Solar cells are the small building blocks of photovoltaics and when connected together they form PV modules. Thin film solar cells require significantly less energy and raw materials to be produced, as compared to the dominant Si wafer technologies. CIGS thin film solar cells are considered to be the most promising thin film alternative due to its proven high efficiency. Most thin film PV modules utilise monolithic integration, whereby thin film patterning steps are included between film deposition steps, to create interconnection of individual cells within the layered structure. The state of the art is that CIGS thin film modules are made using one laser patterning step (P1) and two mechanical patterning steps (P2 and P3). Here we present work which successfully demonstrates the replacement of mechanical patterning by laser patterning methods. The use of laser ablation promises such advantages as increased active cell area and reduced maintenance and downtime required for regular replacement of mechanical tools. The laser tool can also be used to transform CIGS into a conducting compound along a patterned line. We have shown that this process can be performed after all semiconductor layers are deposited using a technique we call laser micro-welding. By performing patterning at the end of the process flow P2 and P3 patterning could be performed simultaneously. Such solutions will further reduce manufacturing times and may offer increased control of semiconductor interfaces. While showing promising performance on par with reference processes there are still open questions of importance for these novel techniques, particularly that of long term stability. Thin film modules are inherently sensitive to moisture and require reliable encapsulation. Before the techniques introduced here can be seen industrially they must have achieved proven stability. In this work we present a proof of existence of stable micro-welded interconnections. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 731

Cu(In,Ga)Se2 (CIGS) thin film solar cells contain a thin layer of CdS. To avoid toxic heavy-metal-containing waste in the module production the development of a cadmium-free buffer layer is desirable. This thesis considers alternative Cd-free buffer materials deposited by Atomic Layer Deposition (ALD). Conditions of the CIGS surface necessary for ALD growth are investigated and the heterojunction interface is characterized by band alignment studies of ZnO/CIGS and In2S3/CIGS interfaces. The thesis also includes investigations on the surface modification of the CIGS absorber by sulfurization. According to ALD theory the growth process is limited by surface saturated reactions. The ALD growth on CIGS substrates shows nucleation failure and generally suffers from surface contaminations of the CIGS layer. The grade of growth disturbance varies for different ALD precursors. The presence of surface contaminants is related to the substrate age and sodium content. Improved growth behavior is demonstrated by different pretreatment procedures. The alignment of the energy bands in the buffer/absorber interface is an important parameter for minimization of the losses in a solar cell. The valence band and conduction band offsets was determined by in situ X-ray and UV photoelectron spectroscopy during layer by layer formation of buffer material. The conduction band offset (ΔEc) should be small but positive for optimal solar cell electrical performance according to theory. The conduction band offset was determined for the ALD ZnO/CIGS interface (ΔEc = -0.2 eV) and the ALD In2S3/CIGS interface (ΔEc = -0.25 eV). A high temperature process for bandgap grading and a low temperature process for surface passivation by post deposition sulfurization in H2S were investigated. It is concluded that the high temperature sulfurization of CuIn(1-x)GaxSe2 leads to phase separation when x>0. The low temperature process did not result in enhanced device performance.

Thesis (M.S.)--Miami University, Dept. of Paper and Chemical Engineering, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 64-69).

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.

Ce travail de thèse s'insère dans la Recherche et Développement du Photovoltaïque. L'objectif était d'étudier, développer et optimiser un nouveau procédé plasma de dépôt pour l'élaboration de couches minces d'oxyde de zinc (ZnO) pour l'application de couche fenêtre dans les cellules solaires de type Cu(In,Ga)Se2. La particularité de ce procédé est de réaliser rapidement des couches d'oxyde (≥ 0,6 nm/s) à partir d'une solution aqueuse de précurseurs non toxiques, interagissant, sous forme de gouttes, avec le plasma. La faisabilité du dépôt de ZnO par le réacteur plasma basse puissance (LPPR) a été vérifiée en obtenant des couches de ZnO homogènes, cristallines et transparentes grâce à l'optimisation des paramètres du réacteur. Le diagnostic du réacteur plasma et la modélisation/simulation du réacteur nous ont permis de constater que l'état physique et la taille des gouttes influent sur la qualité des couches d'oxyde. Des cellules solaires ont été réalisées permettant de valider la qualité des couches de ZnO obtenues via notre procédé plasma. Les meilleurs rendements sont d'environ 14 % ce qui est très prometteur pour les recherches futurs. L'étude du dopage de type N du ZnO a été abordé dans le but de réaliser une couche fenêtre complète par le réacteur LPPR. Cependant beaucoup d'améliorations et d'études restent à faire telles que la mise en place d'un système d'injection sophistiqué, ou encore l'investigation approfondie sur le dopage. Néanmoins une étude des coûts matières/énergie du procédé a été réalisée afin de pouvoir positionner le réacteur plasma parmi les autres techniques employées pour la réalisation de cellules CIGS. / This work is part of the Research and Development of Photovoltaic. The aim was to study, develop and optimize a new deposition plasma process for the elaboration of zinc oxide thin layers (ZnO) as the window layer in Cu(In,Ga)Se2 solar cells of. The particularity of this process is to quickly realize oxide layers (≥ 0.6 nm/s) from an aqueous solution of non-toxic precursors, interacting in the form of droplets, with the plasma. The feasibility of the ZnO deposition by the low power plasma reactor (LPPR) was checked by obtaining homogeneous, crystalline and transparent layers of ZnO thanks to the optimization of reactor parameters. The diagnostic and modeling / simulation of the plasma reactor allowed us to see that the physical state and droplet size affect the quality of the oxide layers. Solar cells were created to validate the quality of ZnO layers obtained via our plasma process. The best obtained efficiency is about 14% which is very promising for future research. The study of doping N type ZnO was addressed in order to achieve a complete window layer by LPPR reactor. However many improvements and studies are still needed, such as the establishment of a sophisticated injection system, or the thorough investigation on doping. Nevertheless a cost study about material/energy of the process was conducted in order to place the plasma reactor among other techniques used for the production of CIGS solar cells.

<div>In this thesis, we propose a model to predict the interfacial delamination in a flexible solar cell. The interface in a multilayer Copper Indium Gallium Diselenide (CIGS) flexible solar cell was studied applying the principles of fracture mechanics to a fixed-arm-peel test. </div><div>The principles of fracture mechanics ( J-integral and cohesive model) were implemented in a finite element software to compare the experimental with the numerical peeling force. A fixed-arm-peel test was used to obtain the peeling force for different peeling angles. This peel force and material properties from the CIGS solar cell were processed in several non-linear equations, so the energy required to start the delamination was obtained.The accuracy of the model was compared by fitting the experimental and numerical peeling force, which had a difference of 0.08 %. It is demonstrated that the peeling process for 90-degree could be replicated in COMSOL® software for a CIGS solar cell.</div>