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Risbridger, Thomas Arthur George. "Aqueous dye sensitized solar cells." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607628.
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Dye sensitized solar cells (DSSCs) have typically been produced using organic liquids such as acetonitrile as the electrolyte solvent. In real world situations water can permeate into the cell through sealing materials and is also likely to be introduced during the fabrication process. This is a problem as the introduction of water into cells optimized to use an organic solvent tends to be detrimental to cell performance. In this work DSSCs which are optimized to use water as the main electrolyte solvent are produced and characterized. Optimization of aqueous DSSCs resulted in cells with efficiencies up to 3.5% being produced. In terms of characterization, it is generally seen in this work that aqueous DSSCs produce a lower photocurrent but similar photovoltage compared to DSSCs made using acetonitrile and reasons for this are examined in detail. The decreased ability of the aqueous electrolyte to wet the nanoporous TiO2 compared to an acetonitrile electrolyte is found to be a key difficulty and several possible solutions to this problem are examined. By measuring the photocurrent output of aqueous cells as a function of xy position it can be seen that there is some dye dissolution near to the electrolyte filling holes. This is thought to be linked to pH and the effect of 4-tert-butylpyridine and may also decrease the photocurrent. It is found that there is little difference between the two types of cells in terms of the conduction band position and the reaction of electrons in the semiconductor with triiodide in the electrolyte, explaining the similarity in photovoltage. By altering the pH of the electrolyte in an aqueous cell it is found to be possible to change the TiO2 conduction band position in the DSSC. This has a significant effect on the open circuit voltage and short circuit current of the cell, though the pH range available is limited by the fact that dye desorbs at high pH values.
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Palma, Giuseppina. "Nanostructured dye-sensitized solar cells." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9972.
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2012/2013Dye-sensitized solar cells (DSSCs) represent a promising alternative to silicon-based technology. From the first publications about DSSCs in the 90s, they are considered an important breakthrough for achieving high efficiency by using relatively inexpensive and abundant materials. Stability and efficiency are two crucial points in the development of this new class of hybrid photovoltaic devices. Most of the DSSC studies carried out over the past twenty years are based on the optimization of these two aspects. In particular, no particular efficiency improvement was obtained in the last period, although many efforts have been made for the research of appropriate solutions able to allow to fabricate more efficient devices. In this scenario, the topic of interest for this thesis is to further enhance the photovoltaic performance of DSSCs by integrating a nano-engineered TiOx photoanode obtained by means of a new nanostructuring method. This novel method, called ASB-SANS (Auxiliary Solvent-Based Sublimation-Aided NanoStructuring) allows the fast nanostructuring of a material in conditions of room temperature and atmospheric pressure. The nanostructuring process occurs by means of an auxiliary sublimating substance that, after having influenced the spatial arrangement of the material to be nanostructured, sublimates away from the system spontaneously. So-obtained TiOx photoanodes are characterized by an inner surface area which is higher than that of commonly used photoanodes. This implies that higher dye loading values are possible, in turn meaning an increase of photogenerated charge carriers upon sunlight absorption, hence an overall increase of the DSSC efficiency. This thesis is structured as following: - Chapter 1 is a general introduction to the photovoltaics and dye-sensitized solar cells, such as the operating principles and the characteristics of the dye cell; - Chapter 2 presents the motivation and objectives of PhD work, with particular interest in the state of art on the semiconductor layer optimization; - Chapter 3 contains a description of the two instrumental systems assembled by the author and colleagues for the characterization of photovoltaic devices (current/voltage recording system and IPCE system). A particular focus is put on the development of a tool for the determination of the photovoltaic quantum efficiency obtained by the conversion of a common UV-Vis spectrometer; - Chapter 4 is focused on the description of two methods for the determination of the active sites (dye grafting points) of the TiOx surface: the first based on the acetic acid adsorption and the second on the dye molecules adsorption. These methods are used for the characterization of all fabricated photoanodes; - Chapter 5 starts with the proven effectiveness of the ASB-SANS method applied to nanostructuring, over relatively large areas, a semiconducting polymer widely used in organic solar cells. The chapter is then focused on the description of the ASB-SANS method applied to fabricate our nano-engineered photoanodes; - Chapter 6 presents the results obtained by the application of the nano-engineered photoanodes in photovoltaic devices; - Chapter 7 reports some final conclusions together with our outlooks in the future research and development of the nano-engineered photoanodes for dye-sensitized solar cells.
Le celle solari a colorante organico (DSSC) proposte da Grätzel rappresentano una promettente alternativa alle tecnologie basate sul silicio già in commercio. Dalle prime pubblicazioni negli anni 90 esse hanno reppresentato un importante passo avanti per raggiungere un’efficienza relativamente alta utilizzando materiali poco costosi e abbondanti in natura. Gli aspetti più importanti per lo sviluppo di questa tecnologia sono la stabilità e l’efficienza, su cui si fonda la maggior parte degli studi sulle DSSC condotti negli ultimi vent’anni. In particolare, nonostante gli sforzi enormi nella ricerca di soluzioni appropriate che consentissero di fabbricare dispositivi più efficienti, nessun particolare incremento di efficienze è stato registrato. In questo scenario, il presente lavoro di tesi ha come scopo il miglioramento della performance fotovoltaica di DSSC attraverso l’integrazione al loro interno di un fotoanodo di TiOx nanostrutturato utilizzando un nuovo metodo di fabbricazione. Questo metodo, denominato ASB-SANS (Auxiliary Solvent- Based Sublimation-Aided NanoStructuring) permette la nanostrutturazione di un materiale senza dispendio di tempo ed in condizioni di temperatura ambiente e pressione atmosferica. La nanostrutturazione di un materiale avviene per mezzo di un sublimante ausiliario che, dopo aver influenzato la disposizione spaziale del materiale, si allontana dal sistema spontaneamente per semplice sublimazione. I fotoanodi di TiOx così ottenuti presentano una superficie esposta all’attacco del colorante maggiore di quella esposta generalmente dai fotoanodi comunemente impiegati. Ciò comporta un aumento della quantità di colorante che il fotoanodo può adsorbire che si traduce in un aumento della quantità di portatori di carica che si possono generare per effetto dell’assorbimento della luce solare. Il miglioramento della corrente generata nel dispositivo influenzerà positivamente l’efficienza globale della cella DSSC. Il presente lavoro di tesi è strutturato nel seguente modo: - il Capitolo 1 costituisce l’introduzione alla tematica di interesse con un approfondimento descrittivo dei componenti di una DSSC e del suo funzionamento; - il Capitolo 2 espone la motivazione e gli obbiettivi del lavoro di dottorato con particolare interesse verso lo stato dell’arte inerente alla motivazione espressa; - il Capitolo 3 contiene la descrizione accurata dei sistemi di caratterizzazione di dispositivi fotovoltaici. Di particolare rilievo è la messa a punto di uno strumento per la determinazione dell’efficienza quantica. Quest’ultimo è stato ottenuto assemblando un comune spettrometro UV-Vis con un multimetro per la registrazione delle correnti generate dalla cella; - il Capitolo 4 improntato sulla descrizione di due metodi per la determinazione dei siti attivi (punti di attacco del colorante) presenti sulla superficie del TiOx: il primo basato sull’adsorbimento dell’acido acetico e il secondo sull’adsorbimento delle molecole di colorante. Tali metodi serviranno per la caratterizzazione dei fotoanodi nanostrutturati; - il Capitolo 5 si apre con la provata efficacia del metodo di nanostrutturazione ASB-SANS applicato su polimeri di interesse fotovoltaico. Il fulcro del capitolo è tutto rivolto alla descrizione del metodo applicato al sistema di nanoparticelle di TiOx, con tute le soluzioni tecniche adottate per renderlo altrettanto efficace su questo genere di sistemi; - il Capitolo 6 riporta i risultati ottenuti per l’applicazione dei fotoanodi del capitolo 5 all’interno dei dispositivi fotovoltaici; - il capitolo 7 conclude il lavoro e riporta le eventuali prospettive per il futuro.
XXVI Ciclo
1984
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Greijer, Agrell Helena. "Interactions in Dye-sensitized Solar Cells." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3752.
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Cameron, Petra Jane. "Studies of dye sensitized solar cells." Thesis, University of Bath, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407482.
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Maluta, Eric N. "Simulations of dye-sensitized solar cells." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538165.
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Zahiko, I. V. "TiO2-based dye-sensitized solar cells." Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/34953.
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Today, due to the increasing global demands on energy, it is imperative that a renewable energy source be determined, that is cost effective and reliable. Solar cell technology has shown much promise over the years to replace the use of fossil fuels. However, with the current technology, the cost per watt is rather high due to the high cost of manufacturing silicon-based solar cells.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34953
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Almodôvar, Vítor Alexandre da Silva. "Diketopyrrolopyrroles for dye-sensitized solar cells." Master's thesis, Universidade de Évora, 2017. http://hdl.handle.net/10174/22074.
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Com foco nos últimos seis anos, o sistema bicíclico dicetopirrolopirrol tem sido cada vez mais utilizado como ”bloco de construção” de materiais (polímeros e moléculas pequenas) para utilização em células solares. Isso deve-se principalmente à sua alta estabilidade ambiental (principalmente fotoestabilidade) e capacidades de transferência de carga. Apesar dos estudos serem ainda recentes, os resultados já alcançados mostraram o tremendo potencial dos dicetopirrolopirróis em células solares.
O trabalho descrito nesta tese de Mestrado envolveu a síntese de vários derivados de dicetopirrolopirrol com o objetivo de introduzir unidades fotossensibilizantes ligadas covalentemente ao sistema dicetopirrolopirrol. Os novos compostos podem vir a incorporar um grupo carboxílico para suportar o corante na superfície de um óxido semicondutor das células solares sensibilizadas por corantes (DSSCs).
A primeira parte do trabalho consistiu na alquilação ou arilação dos grupos NH de dicetopirrolopirróis comerciais. Posteriormente, foram estudados métodos de funcionalização dos grupos arilo nas posições 3 e 6 dos DPP por reações catalisadas por paládio ou por clorossulfonação. Todos os dicetopirrolopirróis sintetizados foram caracterizados por ressonância magnética nuclear, espetrometria de massa e espectrofotometria de UV-visível. Alguns compostos foram também caracterizados por fluorescência; Abstract:
With a focus on the last six years, the bicyclic diketopyrrolopyrrole (DPP) system has been increasingly used as an active building block in materials (polymers and small molecules) used in solar cells. That is mainly due to its high environmental stability (mainly photostability) and charge transfer capabilities. Despite its infancy, the results already achieved have shown the tremendous potential of diketopyrrolopyrroles in solar cells.
The work reported in this Master thesis involved the synthesis of several diketopyrrolopyrrole derivatives aiming introducing photosensitizing units covalently linked to the diketopyrrolopyrrole system. The new compounds may be functionalized with carboxylic groups to support the dye firmly at the surface of a semiconductor oxide of dye-sensitized solar cells (DSSCs).
The first part of the work consisted in the alkylation or arylation of the NH groups of commercially available DPP. Then, new methods for the functionalization of the aryl groups at 3 and 6 positions of DPP were studied, mainly by palladium catalysed reactions or by chlorosulfonation. All diketopyrrolopyrrole derivatives synthesized were characterized by nuclear magnetic resonance, mass spectrometry and UV-vis spectrophotometry. Some compounds were also characterized by fluorescence.
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BELLA, FEDERICO. "Photopolymers for dye-sensitized solar cells." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2594972.
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Energy and environment have become the two predominant scientific research areas in the 21st century, and in some ways they are closely interconnected. Fossil fuels can no longer represent the predominant energy supply for human being. Their use must be reduced and alternative sustainable energy resources have to be identified and rapidly exploited. In the coming decades, the exploited energy sources will not only affect economy and politics but, in fact, health itself. The most direct and obvious effect derived from the current intensive use of fossil fuels is linked to the global warming caused by greenhouse gas emissions. The World Health Organization has recently estimated an increase of five million patients and 150,000 deaths per year resulting from the recent global temperature increase. Indirect effects are also important, such as the increase of infectious diseases transmitted by insects (especially malaria) and the deterioration of overall health due to malnutrition, as a direct consequence of drought and famine. Finally, the continuous use of fossil fuels boosts global pollution, which in turn significantly increases the mortality for respiratory and cardiovascular diseases.
Global energy supply system must be urgently reassessed exploiting the use of clean energy sources. To this purpose, investments for the development of renewable energy resources are increasing worldwide, with particular attention to the most mature technologies such as hydro, wind and solar power. In particular, photovoltaics stands out as the most effective technology to be intensively exploited, especially if one considers that the total solar energy absorbed by Earth in one hour is higher than the overall yearly energy use. Many different photovoltaic devices have been developed over the last sixty years, and the large-scale production of solar panels having good efficiencies has begun in the last decade and is rapidly growing. The major goal is to find a trade-off between efficiency, stability, cost and environmental impact of the solar cells. This has led to a lively scientific research in this direction, in a multidisciplinary environment that includes materials scientists, electronic engineers, technologists and experts of life cycle assessment.
The dye-sensitized solar cell (DSSC) is a photoelectrochemical device proposed in 1991, composed of widely available and cheap materials. Due to its ease of manufacture, versatility in the choice of components, good efficiency even in the presence of low irradiation level and adaptability to flexible substrates, DSSC has received considerable attention from the scientific community. However, despite the record efficiency of 13% and the recent large-scale industrial production, DSSCs still suffer from poor long-term stability, mainly due to the presence of the volatile liquid electrolyte as well as photosensitive organic components.
In such a scenario, the scope of this PhD Thesis is the development of innovative quasi-solid electrolytes and external coatings where specifically designed polymeric networks are able to impart both high stability and efficiency to the resulting DSSCs.
In Chapter 1 the current global energy scenario is thoroughly presented, along with an overview of the technologies developed for the conversion of solar energy into electricity. The physical parameters useful for the evaluation of the photovoltaic device performance are detailed and the state of art efficiencies so far achieved by means of the current technologies are reviewed.
Chapter 2 deals with the basic concepts for DSSCs; cell architectures, components and operating principle are detailed. The specific characterization methodologies developed for the study of DSSCs are also described.
Chapter 3 is focused on DSSC stability, which represents a key issue of the current solar energy research. The two main strategies to achieve stable DSSCs (i.e., the replacement of liquid electrolytes with polymeric ones and the introduction of external multifunctional polymeric coatings) are reviewed. As regards the preparation of these materials, photopolymerization is presented as one of the most promising technique due to its unique features such as rapidity and environmental friendliness, which are highly desired in a low impact and cheap technology like DSSC.
The experimental part of this Thesis deals with the research work carried out on the preparation, characterization and testing of photopolymerized electrolytes and coatings. Both of these components have been investigated by means of an approach that started with the identification of suitable UV-curable monomers, followed by the study of the relationship between materials and devices performance, and concluded with the optimization through the introduction of particular additives able to give the material a multifunctional feature. In Chapter 4 the preparation and characterization techniques used for the fabrication and analysis of cell components and devices are briefly described. The experimental work has been carried out in the Center for Space Human Robotics (Istituto Italiano di Tecnologia, Torino) and in the Department of Applied Science and Technology (Politecnico di Torino).
In Chapter 5, UV-crosslinked polymer electrolyte membranes (PEMs) are proposed and demonstrated as efficient and stable DSSC electrolytes. Physico-chemical, thermal, viscoelastic and electrochemical techniques are used to investigate the correlation between chemical structure of PEMs and resulting DSSC performance, with a special focus on the transport phenomena within PEMs as well as at the interface with the cell electrodes. The experimental conditions for the preparation of the polymer electrolyte are optimized by a design of experiments approach, which is used in the DSSC research field for the first time. Light-to-electricity conversion efficiency values of the lab-scale DSSCs assembled with these polymer electrolytes are admirably almost equal to the corresponding liquid cells, moreover a remarkably better long-term stability is obtained.
In Chapter 6, a step forward is proposed, where three unconventional approaches are exploited for the successful implementation of photocrosslinked PEMs, namely the fabrication of flexible devices, the preparation of PEMs having a gradient-tailored spatial composition and the in situ photopolymerization of electrolytes containing alternative redox couples. These three themes are definitely innovative in the DSSC field and represent important advances from a technological viewpoint.
Since the use of functional fillers has been scarcely considered in the DSSCs literature so far, the idea of improving both cell efficiency and durability by their introduction in PEMs is proposed in Chapter 7. In this respect, metal-organic frameworks (MOF) and nanocellulose are introduced in UV-cured membranes, and their effect on photovoltaic and stability performance is investigated. In particular, a novel bio-sourced filler is demonstrated to cumulatively increase the photocurrent, the photovoltage and the long-term stability of a polymeric lab-scale DSSC.
In Chapter 8, the protection of DSSCs from UV radiation and atmospheric agents by the application of photopolymerized coatings is proposed. Multifunctional coatings, able both to convert the harmful UV light into harvestable visible light by downshifting and to confer self-cleaning and water-repellent properties to the external side of the cells are investigated. For the first time, a general approach that simultaneously improves performance and weatherability of organic DSSC devices is presented, and it is noteworthy that these multipurpose coatings are obtained by means of a rapid and up-scalable photopolymerization process.
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Pellejà, i. Puxeu Laia. "Exploring novel dye concepts in dye sensitized solar cells." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/284156.
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Aquesta tesi es basa en un tipus de dispositius fotovoltaics, les cel•les solars sensitivitzades amb colorant. Des de fa un parell de dècades, l’estudi d’aquests dispositius ha anat en augment i actualment ja s’han publicat resultats amb més d’un 13% d’eficiència. S’estudien els diferents components d’aquest dispositiuis, la seva funció i totes les reaccions i fenòmens físics que hi tenen lloc. S’explica com es prepara aquest tipus de dispositius i com es caracteritzen. Finalment, hi ha un recull de 6 articles publicats i entre ells es diferencien pel tipus de colorant utilitzat: porfirines, ftalocianines, colorants orgànics que tenen una estructura anomenada dadora-acceptora amb un pont tipus π entremig i complexes de ruteni.This thesis is based on a type of photovoltaic devices; the dye sensitized solar cells (DSCs). In the last two decades, the study of these devices has been increased and currently results with over 13% efficiency have been published. The first chapter discusses the various components of this kind of device, its function and its components. It is also explained how these cells work and all the reactions and physical phenomena that take place. The second chapter explains how to prepare these devices and how are characterized. And the third, fourth, fifth and sixth chapters are based on diverse articles published and the difference between them is the kind of dye. In chapter 3, the dyes used are porphyrins, chapter 4 is based on phthalocyanines, chapter 5 is centred on organic dyes that have a structure called donor-acceptor with a π-bridge type in between and chapter 6 studies two ruthenium complexes.
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Jim, Wai-yan, and 詹煒炘. "Tin oxide based dye sensitized solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206431.
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Dye sensitized solar cells (DSSCs) have received extensive attention among solar cells in recent years as the production cost is comparatively low and photovoltaic performance is good. Apart from TiO2, SnO2-based DSSCs are of great interest since SnO2 has a wide band gap and high mobility. Though the conversion efficiency of SnO2-based DSSCs is still not comparable to TiO2-based DSSCs, there is room for improvement to fabricate an efficient device. In this study, different commercial SnO2 nanoparticles have been compared. The number of SnO2 layers and paste formulation have been optimized. The effects of TiCl4 and TTIP treatments have been investigated.
In order to further optimize the performance of SnO2-based DSSCs, different strategies have been adopted to increase dye loading, facilitate electron transport and enhance photon absorption. Different dopants (Zn, Mg and Ag) have been introduced to SnO2 pastes. It is found that cells with Zn dopants perform the best with increased dye uptake. SnO2 nanorods have been synthesized and mixed with SnO2 nanoparticles. More nanorods result in faster electron transport and hence increase the conversion efficiency. In addition, different gold nanostructures (nanostars, nanorods and nanocubic Au) have been synthesized and incorporated into SnO2 photoanodes to study the plasmonic effects. It can be observed that nanocubic Au demonstrates the largest improvement in conversion efficiency. The obtained results will be discussed in detail.published_or_final_version
Physics
Master
Master of Philosophy
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Ruiz, Raga Sonia. "Advanced Studies on Dye-Sensitized Solar Cells." Doctoral thesis, Universitat Jaume I, 2013. http://hdl.handle.net/10803/396360.
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The conversion of sunlight into electricity is one of the most promising energy sources because is renewable and available worldwide. Therefore, is desirable to develop low cost, stable and efficient photovoltaic devices that can compete with the expensive silicon solar panels. Dye-sensitized solar cells (DSC) are a promising photovoltaic technology based on low-cost materials and fabrication processes with power-conversion efficiencies over 12%. DSC harvest light thanks to a photoactive organic molecule, and extracts the charges through different materials. The analysis of the working principles of these complex devices is essential in order to achieve further improvements on the solar cell efficiency. The aim of this thesis is to analyze and identify the electrical interactions between the internal materials and interfaces of a DSC by means of impedance spectroscopy (IS). We provide useful interpretation of IS applied to DSC and insights on DSC development such as implementation of photonic crystals and up-scaling to modules, as a first step for a future commercialization.Convertir la llum solar en electricitat és una de les maneres més prometedores d'obtindre energía, ja que és inesgotable i disponible arreu del món. Primer és necessari desenvolupar dispositius fotovoltaics què siguin eficients, estables i de baix cost, i així poder competir en el mercat amb les actuals cèl·lules solars de silici. Les cèl·lules solars sensitivitzades amb colorant (DSC) ja han assolit eficiències per sobre del 12% amb materials i processos de fabricació senzills i barats. Les DSC recol·lecten la llum gracies a unes molècules fotoactives (colorant) i extrauen les càrregues a través de diferents materials semiconductors. Analitzar els principis de funcionament d'aquests dispositius és essencial per a assolir futures millores en eficiència i estabilitat. L'objectiu d'aquesta tesi és analitzar i identificar les interaccións elèctriques entre els materials i interfases internes d'una DSC mitjançant l'espectroscopía d'impedància (IS). El treball proporciona una interpretació pràctica de la IS aplicada a les DSC i també altres idees per al desenvolupament de les DSC com ara l'ús de cristalls fotònics i la fabricació de moduls de gran àrea, com a primer pas per a una futura comercialització.
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Nilsing, Mattias. "Computational Investigation of Dye-Sensitized Solar Cells." Doctoral thesis, Uppsala universitet, Avdelningen för kvantkemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7673.
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Interfaces between semiconductors and adsorbed molecules form a central area of research in surface science, occurring in many different contexts. One such application is the so-called Dye-Sensitized Solar Cell (DSSC) where the nanostructured dye-semiconductor interface is of special interest, as this is where the most important ultrafast electron transfer process takes place. In this thesis, structural and electronic aspects of these interfaces have been studied theoretically using quantum chemical computations applied to realistic dye-semiconductor systems. Periodic boundary conditions and large cluster models have been employed together with hybrid HF-DFT functionals in the modeling of nanostructured titanium dioxide. A study of the adsorption of a pyridine molecule via phosphonic and carboxylic acid anchor groups to an anatase (101) surface showed that the choice of anchor group affects the strength of the bindings as well as the electronic interaction at the dye-TiO2 interface. The calculated interfacial electronic coupling was found to be stronger for carboxylic acid than for phosphonic acid, while phosphonic acid binds significantly stronger than carboxylic acid to the TiO2 surface. Atomistic and electronic structure of realistic dye-semiconductor interfaces were reported for RuII-bis-terpyridine dyes on a large anatase TiO2 cluster and perylene dyes on a periodic rutile (110) TiO2 surface. The results show strong influence of anchor and inserted spacer groups on adsorption and electronic properties. Also in these cases, the phosphonic acid anchor group was found to bind the dyes significantly stronger to the surface than the carboxylic acid anchor, while the interfacial electronic coupling was stronger for the carboxylic anchor. The estimated electron injection times were twice as fast for the carboxylic anchor compared to the phosphonic anchor. Moreover, the electronic coupling was affected by the choice of spacer group, where unsaturated spacer groups were found to mediate electron transfer more efficiently than saturated ones.
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Wills, Kathryn. "Copper dyes for dye-sensitized solar cells." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636545.
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This thesis studies the application of copper(I) complexes as the sensitizing component of dye sensitized solar cells (DSCs). Ruthenium(II) polypyridyl complexes have been widely studied and shown great success for the past two decades; however the metal is rare and expensive. A copper(I) based DSC could offer a viable alternative to using ruthenium(II) dyes, taking into account the cost and sustainability advantages. Interest in copper(I) DSCs has reignited over the past five years and the work in this thesis begins by reproducing the synthesis of one of the first reported complexes, [Cu(6,6’-dimethyl-2,2’-bipyridine-4,4’-dicarboxylic acid)2][Cl]. A more detailed study of the dye and its properties will be described, including assessing the effect of TiO2 film dye time on DSC performance, electrochemical studies and coupling the dye with a Co2+/3+ mediator. In the following chapters, improvements to the basic 2,2’-bipyridine framework are investigated. An experimental and computational investigation with a [Cu(2,2'-biquinoline-4,4'-dicarboxylic acid)2][HNEt3] complex is presented, where the 2,2’-biquinoline ligand has been chosen as a bulkier, more conjugated alternative to the 2,2’-bipyridine ligand. Although DSC efficiencies with this complex are comparatively low, an investigation into possible reasons for this is described. This thesis then considers functionalisation of a 2,2’-bipyridine ligand with halide and thiophene substituents. Several new ligands and copper(I) complexes are described and characterised. A top DSC efficiency of 1.41% was obtained with a [Cu(6,6'-dimethyl-[2,2'-bipyridine]-4,4'-diyl)bis(thiophene-2-carboxylic acid)2][PF6] dye. The synthetic route towards this complex and an analysis of its features, such as emissive behaviour, electrochemical properties and electron diffusion length, are described.
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Ellis, Hanna. "Developing Environmentally Friendly Dye-sensitized Solar Cells." Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280291.
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Due to climate change and its effects, alternative renewable energy sources are needed in the future human society. In the work of this thesis, the Dye-sensitized Solar Cell (DSC) has been investigated and characterized. DSCs are appealing as energy conversion devices, since they have high potential to provide low cost solar light to electricity conversion. The DSC is built up by a working electrode consisting of a conductive glass substrate with a dye-sensitized mesoporous TiO2 film, a counter electrode with a catalyst and, in between, the electrolyte which performs the charge transport by means of a redox mediator. The aim of this thesis was to develop and evaluate cheap and environmentally friendly materials for the DSC. An alternative polymer-based counter electrode catalyst was fabricated and evaluated, showing that the PEDOT catalyst counter electrode outperformed the platinum catalyst counter electrode. Different organic dyes were evaluated and it was found that the dye architecture affected the performance of the assembled DSCs. A partly hydrophilic organic triphenylamine dye was developed and applied in water-based electrolyte DSCs. The partly hydrophilic dye outperformed the reference hydrophobic dye. Small changes in dye architecture were evaluated for two similar dyes, both by spectroscopic and electrochemical techniques. A change in the length of the dialkoxyphenyl units on a triphenylamine dye, affected the recombination and the regeneration electron transfer kinetics in the DSC system. Finally, three water soluble cobalt redox couples were developed and applied in water-based electrolyte DSCs. An average efficiency of 5.5% (record efficiency of 5.7%) for a 100% water-based electrolyte DSC was achieved with the polymer-based catalyst counter electrode and an organic dye with short dimethoxyphenyl units, improving the wetting and the regeneration process.
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MARCHINI, EDOARDO. "New Components for Dye Sensitized Solar Cells." Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2496481.
Full textAbstract:
Due to the strong increase in the world energy consumption, and need of exploiting carbon neutral energy sources, increasing efforts have been devoted to the exploitation of solar energy technology. For their unique properties, Dye Sensitized Solar Cells (DSSC) could complement the established silicon junctions. This Ph.D. thesis is mainly focused on the understanding of the (photo)/electrochemical properties of new components for DSSCs. The first chapter, realized in collaboration with the Prof. Stagni’s group, is about the characterization of new examples of Ru(II)-tetrazolato dyes as thiocyanate-free sensitizers for solar cell applications. Four complexes (D1-D4) have been analyzed together with the well know standard N719. The combination of the electrochemical and spectroscopic analyses revealed ground and excited states thermodynamic properties suitable for efficient interfacial charge separation. These features resulted in external quantum yield of photon to electron conversions higher than 80%. The best performances have been recorded in the case of D4 thanks to the combinations of the broader harvesting, efficient regeneration, and electron injection. Three chapters of my thesis report about the collaborative research carried out with the groups led by Dr. P.C. Gros and Dr. M.C. Pastore, involving the investigation of the electronic properties of Fe(II)NHC (NHC=N-Heterocyclic-Carbene) sensitizers. First, we tried to rationalize the charge transfer dynamics of C1 a homoleptic complex bearing σ-donating NHCs and π-accepting carboxylic groups, which initially reported rather low performances (0.13 % of PCE%). We achieved a substantial progress in cell efficiency (PCE = 1%). We estimated an injection quantum yield (Φinj) of ca. 50% that, is believed to be the main limitation for the rather low PCE. In consideration of the excited state energetics, nearly optimal for injection into TiO2, this relatively low Φinj could be due to a non-optimal electronic coupling arising from the symmetric design of the homoleptic C1. For this reason, we moved to Fe(II)NHC heteroleptic designs characterized by an asymmetric coordination sphere. The first complex was the asymmetric analogue of C1 named ARM13, while other design incorporated spacers between the anchoring moieties and the pyridine linked to the metal center, in particular, a thiophene in the case of ARM7 and a phenyl ring in the case of ARM11. The rationale behind such designs was to increase the electron-hole separation and the light harvesting capability. We were able to obtain the highest power conversion efficiency (ARM13 ca. 1.5%) ever reported for a Fe(II) sensitizer. In a third project, we designed, realized and characterized a new family of heteroleptic Fe(II)NHC complexes bearing electron withdrawing or donating substituents on the ancillary ligands. In particular, among the new series, ARM130 bearing a dimethoxyphenyl group, exhibited the best performance, thanks to its improved light harvesting capability introduced by the electron-donating -OMe moieties. We obtained a Power Conversion Efficiency of 1.83%. The last chapter of my thesis is about the investigations of alternative counter electrode (CE) materials for DSSCs based on the poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer. The best and well-known electrocatalyst PEDOT/ClO4 (PER) involves the use of organic solvents, greener and sustainable alternative deposition routes are desirable. We explored the electrochemical properties of PEDOT/Nafion CE (NAF), produced through water- based electropolymerization. The electrocatalytic behavior of PER and NAF has been investigated in STLC by means of LSV and EIS, in the presence of either Co- or Cu- based electrolyte, NAF rivals the kinetic and mass transport properties of PER. This result was confirmed by the performance of D35 sensitized solar cells, where NAF counter electrodes generated comparable efficiency of those recorded for PER.A causa dell’aumento della richiesta energetica e della necessità di esplorare risorse sostenibili, ingenti sforzi sono rivolti verso l’applicazione di tecnologia solare. Grazie alle loro peculiarità, le Celle Solari Sensibilizzate con Colorante (DSSCs) potrebbero essere uno strumento complementare alla tecnologia al silicio. Questa tesi di Dottorato è incentrata nella comprensione delle proprietà (foto)/elettrochimiche di nuovi componenti per DSSCs. Il primo capitolo sperimentale, realizzato in collaborazione con il gruppo del Prof. Stagni, ha avuto come scopo la caratterizzazione di nuovi sensibilizzatori di Ru(II)-tetrazolati come esempio di complessi privi di leganti tiocianati. Quattro complessi (D1-D4) sono stati studiati assieme al ben noto standard di rutenio N719. La combinazione dell’analisi elettrochimica e spettroscopica ha evidenziato come la termodinamica dello stato fondamentale ed eccitato sia in grado di favorire un’efficiente separazione di carica. Queste caratteristiche hanno portato ad una resa quantica di conversione di fotoni in elettroni superiore all’80%. D4 è risultato essere il complesso più efficiente grazie alla combinazione della più estesa estensione spettrale, efficiente rigenerazione ed efficiente iniezione di carica. Gran parte della mia attività, tuttavia, è stata rivolta allo studio di sensibilizzatori per DSSCs a base di ferro. Tre capitoli, in collaborazione con i gruppi del Dr. P. C. Gros e dalla Dr. M. C. Pastore, riportano l’investigazione delle proprietà elettroniche di sensibilizzatori di Fe(II)NHC. Nel primo di questi abbiamo studiato le proprietà di trasferimento dinamiche di un complesso omolettico denominato C1, caratterizzato da leganti NHC σ-donatori e gruppi carbossilici π-accettori, il quale aveva inizialmente restituito valori di efficienza dello 0.13%. Abbiamo ottenuto un sostanziale aumento di efficienza ottenendo valori vicini all’1%. Il rendimento quantico di iniezione di carica è risultato essere attorno al 50% e costituisce il principale fattore limitante per le DSSCs a base di ferro. L’energetica dello stato eccitato è risultata ottimale per un’efficiente iniezione di carica quindi, le limitate prestazioni esibite da C1 derivano dal suo design simmetrico che porta ad un accoppiamento elettronico non favorevole con la superficie. Abbiamo così analizzato complessi carbenici eterolettici, il primo di questi era l’analogo asimmetrico di C1, ARM13, altri due invece erano caratterizzati dall’introduzione di un anello tiofenico (ARM7) e uno fenilico (ARM11) aventi la funzione di spaziatori fra le funzionalità ancoranti e le piridine coordinate al metallo centrale. L’idea di questo nuovo design era quella di aumentare la separazione di carica ed incrementare la capacità di raccolta di fotoni. Abbiamo ottenuto la più alta efficienza di cella riportata in letteratura del 1.5% per ARM13. In un terzo progetto abbiamo analizzato una nuova famiglia di complessi eterolettici caratterizzati dall’introduzione di gruppi elettron-donatori o elettron-attrattori sui leganti ancillari. ARM130, caratterizzato da una funzionalità dimetossifenilica, ha restituito le migliori performances dell’1.83%. L’ultimo capitolo della mia tesi riguarda invece lo studio di un controelettrodo (CE) alternativo per DSSCs basato su polimeri conduttori a base di poli(3,4-etilendiossitiofene) (PEDOT), fra questi il ben noto PEDOT/ClO4 (PER), elettropolimerizzato da solventi organici, risulta essere il miglior materiale elettrocatalitico. Al fine di studiare soluzioni più sostenibile, abbiamo esplorato le proprietà elettrochimiche di CE a base di PEDOT/Nafion (NAF) prodotti in ambiente acquoso. Il comportamento elettrocatalitico di PER e NAF è stato investigato in celle simmetriche mediante LSV ed EIS e in celle solari in presenza di D35, quest’ultimo ha generato efficienze di cella comparabili a quelle registrate in presenza di PER.
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DELL'ORTO, ELISA CAMILLA. "Dye sensitized solar cells: materials and processes." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28476.
Full textAbstract:
During the thesis the DSSCs optimization was analyzed mainly through two strategies: the study of new sensitizers and the study
of alternatives materials for photo-cathode fabrication.
Two class of sensitizers were be analyzed: squaraine dyes and cyclometalated-based dyes. Then a study on dye-loading process will be presented, with implication in an industrialization process. For the photo-cathode fabrication two di erent materials were studied, a carbon based material and a polymeric material.
Then a part of the work concerned the study of devices analysis system. In particular electrochemical impedance spectroscopy was
studied to propose a new set up to analyze electric processes in different cell components.3
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LEANDRI, VALENTINA. "Organic materials for dye-sensitized solar cells." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/49809.
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Li, Sin-lai Emily, and 李倩麗. "Theoretical study of dye-sensitized solar cell (DSSC)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41897195.
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Li, Sin-lai Emily. "Theoretical study of dye-sensitized solar cell (DSSC)." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41897195.
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Yu, Ze. "Liquid Redox Electrolytes for Dye-Sensitized Solar Cells." Doctoral thesis, KTH, Oorganisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-64139.
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This thesis focuses on liquid redox electrolytes in dye-sensitized solar cells (DSCs). A liquid redox electrolyte, as one of the key constituents in DSCs, typically consists of a redox mediator, additives and a solvent. This thesis work concerns all these three aspects of liquid electrolytes, aiming through fundamental insights to enhance the photovoltaic performances of liquid DSCs. Initial attention has been paid to the iodine concentration effects in ionic liquid (IL)-based electrolytes. It has been revealed that the higher iodine concentration required in IL-based electrolytes can be attributed to both triiodide mobility associated with the high viscosity of the IL, and chemical availability of triiodide. The concept of incompletely solvated ionic liquids (ISILs) has been introduced as a new type of electrolyte solvent for DSCs. It has been found that the photovoltaic performance of ISIL-based electrolytes can even rival that of organic solvent-based electrolytes. And most strikingly, ISIL-based electrolytes provide highly stable DSC devices under light-soaking conditions, as a result of the substantially lower vapor pressure of the ISIL system. A significant synergistic effect has been observed when both guanidinium thiocyanate and N-methylbenzimidazole are employed together in an IL-based electrolyte, exhibiting an optimal overall conversion efficiency. Tetrathiafulvalene (TTF) has been investigated as an organic iodine-free redox couple in electrolytes for DSCs. An unexpected worse performance has been observed for the TTF system, albeit it possesses a particularly attractive positive redox potential. An organic, iodine-free thiolate/disulfide system has also been adopted as a redox couple in electrolytes for organic DSCs. An impressive efficiency of 6.0% has successfully been achieved by using this thiolate/disulfide redox couple in combination with a poly (3, 4-ethylenedioxythiophene) (PEDOT) counter electrode material under full sunlight illumination (AM 1.5G, 100 mW/cm2). Such high efficiency can even rival that of its counterpart DSC using a state-of-the-art iodine-based electrolyte in the systems studied.The cation effects of lithium, sodium and guanidinium ions in liquid electrolytes for DSCs have been scrutinized. The selection of the type of cations has been found to exert quite different impacts on the conduction band edge (CB) of the TiO2 and also on the electron recombination kinetics, therefore resulting in different photovoltaic behavior.QC 20120124
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Toman, Elizabeth. "ZnO & Zn₂SnO₄ dye sensitized solar cells." Connect to resource, 2007. http://hdl.handle.net/1811/25204.
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Thesis (Honors)--Ohio State University, 2007.Title from first page of PDF file. Document formatted into pages: contains 22 p.; also includes graphics. Includes bibliographical references (p. 22). Available online via Ohio State University's Knowledge Bank.
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Feldt, Sandra. "Alternative Redox Couples for Dye-Sensitized Solar Cells." Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-192694.
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Dye-sensitized solar cells (DSCs) convert sunlight to electricity at a low cost. In the DSC, a dye anchored to a mesoporous TiO2 semiconductor is responsible for capturing the sunlight. The resulting excited dye injects an electron into the conduction band of the TiO2 and is in turn regenerated by a redox mediator, normally iodide/triiodide, in a surrounding electrolyte. The success of the iodide/triiodide redox couple is mainly attributed to its slow interception of electrons at the TiO2 surface, which suppresses recombination losses in the DSC. One of the main limitations with the iodide/triiodide redox couple is, however, the large driving force needed for regeneration, which minimizes the open circuit voltage and thus the energy conversion efficiency. In this thesis, alternative redox couples to the iodide/triiodide redox couple have been investigated. These redox couples include the one-electron transition metal complexes, ferrocene and cobalt polypyridine complexes. The use of one-electron redox couples in the DSC has previously been shown to lead to poor photovoltaic performances, because of increased recombination. Cobalt redox couples were here found to give surprisingly high efficiencies in combination with the triphenylamine-based organic dye, D35. The success of the D35 dye, in combination with cobalt redox couples, was mainly attributed to the introduction of steric alkoxy chains on the dye, which supress recombination losses. By introducing steric substituents on the dye, rather than on the redox couple, mass transport limitations could in addition be avoided, which previously has been suggested to limit the performance of cobalt complexes in the DSC. The result of this study formed the basis for the world record efficiency of DSCs of 12.3 % using cobalt redox couples. Interfacial electron-transfer processes in cobalt-based DSCs were investigated to gain information of advantages and limitations using cobalt redox couples in the DSC. The redox potentials of cobalt redox couples are easily tuned by changing the coordination sphere of the complexes, and regeneration and recombination kinetics were systematically investigated by increasing the redox potential of the cobalt complexes. Our hope is that this thesis can be a guideline for future design of new redox systems in DSCs.
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Jennings, James Robert. "Characterization and modelling of dye-sensitized solar cells." Thesis, University of Bath, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508716.
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Tan, Kwan Wee. "Commercialization potential of dye-sensitized mesoscopic solar cells." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/54206.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 67-73).
The price of oil has continued to rise, from a high of US$100 per barrel at the beginning 2008 to a new record of above US$140 in the recent weeks (of July). Coupled with increasing insidious greenhouse gas emissions, the need to harness abundant and renewable energy sources is never more urgent than now. The sun is the champion of all energy sources and photovoltaic cell production is currently the world's fastest growing energy market. Dye-sensitized solar cells (DSCs) are photoelectrochemical cells which mimic the natural photosynthesis process to generate solar electricity. Typically, a monolayer of dye sensitizer molecules is anchored onto a semiconductor mesoporous film such as TiO₂ to generate charges on exposure to illumination. The nanocrystalline particulate threedimensional network provides high surface area coverage for the photogeneration process and percolation of charges. In the thesis, we will review the current research efforts to optimize the DSC performance and develop probable applications to complement existing solid-state photovoltaic technologies. We believe the large and rapidly expanding solar market offers a prime commercial opportunity to deliver a DSC product for mass adoption by consumers. DSC is kept at a low production cost because it bypasses conventional vacuum-based semiconductor processing technologies, instead relying on solution and chemical processing routes. However, our cost modeling analysis show the TCO glass substrate and ruthenium dyes could constitute more than 90% of the overall materials cost.
(cont.) Thus, we recommend new technological approaches must be taken to keep the substrate pricing low and continuously improve the energy conversion efficiencies to further lower the production cost.
by Kwan Wee Tan.
M.Eng.
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Ellis, Hanna. "Characterization of dye-sensitized solar cells : Components for environmentally friendly photovoltaics." Licentiate thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229939.
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As fossil fuels, the major source of energy used today, create the greenhouse gas carbon dioxide which causes global warming, alternative energy sources are necessary in the future. There is a need for different types of renewable energy sources such as hydropower, windpower, wave- power and photovoltaics since different parts of the world have different possibilities. The sun is a never ending energy source. Photovoltaics use the energy of the sun and converts it into electricity. There are different types of photovoltaics and a combination of them could provide humankind with energy in a sustainable way. In this thesis dye-sensitized solar cells are investigated. Materials for the counter electrode have been investigated and resulting in a polymer based cathode outperforming the traditionally used platinized counter electrode in a cobalt-based redox mediator system (paper I). The sensitizer of the TiO2 was investigated, in this study by modifications of the π-linker unit in an organic donor-linker-acceptor based dye. Four new dyes were synthesized, all four showing extended absorption spectra compared to the reference dye. However, it was found that increasing the absorption spectrum does not neces- sarily increase the power conversion efficiency of the solar cell (paper II). In the last part of this thesis, water-based electrolyte dye-sensitized solar cells were investigated. A hydrophilic dye with glycolic chains close to the center of regeneration was synthesized. The results show increased wettability by water-based electrolyte for the sensitized surface, increased regenera- tion and performance for the hydrophilic dye compared to a hydrophobic dye (paper III). The glycolic chains complex with small cations such as Na+ and K+ in the electrolyte, this proba- bly facilitate the regeneration of the hydrophilic dye even further (paper IV). In this thesis new materials for a more environmentally friendly dye-sensitized solar cell are investigated.
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Lee, Kee Eun. "Investigation of the dye-anatase interface in dye sensitized solar cells." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107837.
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The scope of this thesis is the study of the dye (N719) - TiO2 (anatase) interface in dye sensitized solar cell (DSSC). The study of the TiO2 semiconductor/Ru complex [cis - (2,2'- bipyridyl - 4,4'- dicarboxylate)2 (NCS)2 ruthenium(II): N719] interface is important in order to understand the sensitization event as the dye and semiconductor are key factors for high conversion efficiency in DSSC. In spite of several studies of the interaction of the N719 dye/TiO2 films, the anchoring mechanism has been debated for a decade because it has not been fully revealed. Thus, this thesis aims at unifying the previous different views on the binding mechanism and the type of groups involved in the N719-TiO2 system as well as further elucidate new spectral information via vibrational spectroscopy (ATR-FTIR and SERRS), imaging techniques (Confocal Raman mapping and ATR-FTIR imaging) and electron spectroscopy (XAS and XPS). The combination of vibrational and electronic spectroscopic results allows for all the operating binding modes on the interface from molecular structure to interfacial electronic structure to be determined.We focused on the spectral change in our Raman and ATR-FTIR spectra rather than depend on ∆ν values (frequency difference) as the only method for differentiating binding modes. Furthermore, the hydroxyl vibrations of the N719 and two distinct nano-crystalline anatase surfaces (Dyesol and our own aqueous-synthesized variety) that occur before / after adsorption and their relation to the binding mechanism were explored using ATR-FTIR, SERRS, Confocal Raman mapping and ATR-FTIR imaging. As a result of this analysis the binding of the N719 dye to TiO2 was proposed to occur through two neighboring carboxylic acid/carboxylate groups via a combination of bidentate-bridging and H-bonding involving a donating group from the N719 (and/or Ti-OH) units and acceptor from the Ti-OH (and/or N719) groups. This binding mechanism was further elucidated by investigating the electronic interactions of TiO2 substrates and the N719 molecules via surface sensitive techniques (XAS and XPS) and probing methods (electron yield) before and after the sensitization event. This allowed us to propose that additional electronic interactions occur through the aromatic electron density of the bipyridine groups and the d states found in TiO2 and.that there is extra H-bonding interaction of the NCS ligand of the dye with the TiO2 surface groups (OH/H2O).From the application standpoint, TiO2 nanocrystalline films were prepared from commercial and aqueous-synthesized precursors by screen printing with the purpose of correlating physical properties and in particular surface TiO2 groups (Ti-OH/Ti-OH2) to DSSC performance. Their morphological features were characterized in terms of particle size, shape, BET surface area, pore size, Raman and AFM analysis. This work showed the distribution of surface Ti-OH/Ti-OH2 groups in Aqueous TiO2 to be qualitatively richer than in Dyesol TiO2. The current–voltage characteristics (I–V), electrical impedance spectroscopy (EIS) and open circuit voltage decay (OCVD) were also investigated in relation to the TiO2 film physical properties. It was found that photoelectrodes composed of surface hydroxyl-rich TiO2 nanocrystalline material exhibits longer electron lifetime attributed to enhanced surface-dye binding that suppresses interfacial recombination. The relations between the film's morphology, adsorption properties, and electrochemical behavior are comprehensively discussed.L'objectif de cette thèse est l'étude de l'interface colorant (N719) – TiO2 (anatase) dans la cellule solaire sensibilisée par un colorant (DSSC). L'étude de l'interface du semiconducteur TiO2/complexe Ru [cis - (2,2'- bipyridyl - 4,4'- dicarboxylate)2 (NCS)2 ruthenium(II): N719] est importante pour comprendre l'évènement du sensibilisation étant donné que le colorant et le semiconducteur sont des facteurs clés pour une conversion à haute efficacité dans la DSSC. En dépit de plusieurs études sur l'interaction au niveau des films colorant N719/TiO2, le mécanisme d'ancrage a été débattu pendant une décennie, et est toujours non complètement connu. Ainsi, cette thèse vise à unifier les différentes points de vue antérieurs sur le mécanisme de fixation et le type de groupements impliqués dans le système N719-TiO2 ainsi que d'élucider de nouvelles informations spectrales moyennant la spectroscopie vibrationnelle (ATR-FTIR et SERRS), Les techniques d'imagerie (la cartographie Raman à confocale et l'imagerie ATR-FTIR) et la spectroscopie électronique (XAS et XPS). La combinaison des résultats de la spectroscopie vibrationnel et électronique permet de déterminer tous les modes de fixation fonctionnels à l'interface de la structure moléculaire et la structure électronique. Nous nous sommes concentrés sur le changement spectral dans les spectres Raman et FTIR-ATR et non seulement aux variations de fréquence Δν, comme étant la seule méthode qui différencie entre les différents modes de fixation. Par ailleurs, les vibrations de l'hydroxyle de N719 et les surfaces de deux distinctes anatase nano-cristalline (Dyesol et nos propres variétés aqueuses synthétisés) qui se produisent avant / après l'adsorption et leur relation avec le mécanisme de fixation ont été explorés par ATR-FTIR, SERRS, cartographie à confocale Raman et l'imagerie ATR-FTIR. En conséquence à cette analyse, la fixation du colorant N719 avec TiO2 a été proposée. Elle se produise à travers deux groupements carboxylique / carboxylate voisins via une combinaison de pontage bidentés et liaisons-H. Ces derniers impliquent un groupement donneur des unités de N719 (et / ou Ti-OH) et accepteur des groupements Ti-OH (et / ou N719). Ce mécanisme de fixation a été ensuite élucidé en étudiant les interactions des substrats de TiO2 et les molécules N719 via les techniques sensitives de surface (XAS and XPS) et les méthodes à sonde (rendement d'électron) avant et après l'évènement de sensibilisation. Cela nous a permis de proposer que les interactions électroniques supplémentaires se produisant à travers la densité des électrons aromatiques des groupes bipyridine et les états d trouvés dans TiO2 et qu'il y a des interactions supplémentaires de liaisons hydrogènes des ligands de NCS du colorant avec les groupements (OH/H2O) de la surface de TiO2. Du point de vue application, les films TiO2 nanocristallins ont été préparés à partir de précurseurs commerciaux et aqueuse synthétisés par sérigraphie dans le but de corréler les propriétés physiques et en particulier les groupements (Ti-OH/Ti-OH2) à la surface de TiO2 par rapport à la performance de la DSSC. Les caractéristiques de leurs morphologies ont été discutés en fonction de la taille des particules, leur forme, leur surface BET, la taille des pores, l'analyse AFM et la spectroscopie Raman. Les caractéristiques courant-tension (I-V), la spectroscopie d'impédance électrique (SIE), le déclin de tension en circuit ouvert (OCVD), ont également été étudiés en relation avec les propriétés physiques du film de TiO2.
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Bergeron, Bryan Vernon. "Approaches to optimize photovoltage in dye-sensitized solar cells." Click to view the dissertation via Digital dissertation consortium, 2004.
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Subbaiyan, Navaneetha Krishnan. "Supramolecular Solar Cells." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149672/.
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Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-p and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.
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Essner, Jeremy. "Dye sensitized solar cells: optimization of Grätzel solar cells towards plasmonic enhanced photovoltaics." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/12416.
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Master of ScienceDepartment of Chemistry
Jun Li
With the worldly consumption of energy continually increasing and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. One promising approach for an alternate method of producing energy is using solar cells to convert sunlight into electrical energy through photovoltaic processes. Currently, the most widely commercialized solar cell is based on a single p-n junction with silicon. Silicon solar cells are able to obtain high efficiencies but the downfall is, in order to achieve this performance, expensive fabrication techniques and high purity materials must be employed. An encouraging cheaper alternative to silicon solar cells is the dye-sensitized solar cell (DSSC) which is based on a wide band gap semiconductor sensitized with a visible light absorbing species. While DSSCs are less expensive, their efficiencies are still quite low compared to silicon. In this thesis, Grätzel cells (DSSCs based on TiO2 NPs) were fabricated and optimized to establish a reliable standard for further improvement. Optimized single layer GSCs and double layer GSCs showing efficiencies >4% and efficiencies of ~6%, respectively, were obtained. Recently, the incorporation of metallic nanoparticles into silicon solar cells has shown improved efficiency and lowered material cost. By utilizing their plasmonic properties, incident light can be scattered, concentrated, or trapped thereby increasing the effective path length of the cell and allowing the physical thickness of the cell to be reduced. This concept can also be applied to DSSCs, which are cheaper and easier to fabricate than Si based solar cells but are limited by lower efficiency. By incorporating 20 nm diameter Au nanoparticles (Au NPs) into DSSCs at the FTO/TiO2 interface as sub wavelength antennae, average photocurrent enhancements of 14% (maximum up to ~32%) and average efficiency enhancements of 13% (maximum up to ~23% ) were achieved with well dispersed, low surface coverages of nanoparticles. However the Au nanoparticle solar cell (AuNPSC) performance is very sensitive to the surface coverage, the extent of nanoparticle aggregation, and the electrolyte employed, all of which can lead to detrimental effects (decreased performances) on the devices.
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Yu, Hua. "Modification of TiO2 Photoanodes for Dye-Sensitized Solar Cells." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366656.
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With the growing demand of the photovoltaic market, high cost of the traditional silicon-based solar cells has been the biggest barrier for its widespread use of solar energy conversion. New generation solar cells, aiming at the low-cost and high- efficiency photovoltaic devices, have been researched for a couple of decades. Among the new generation solar technologies, dye-sensitized solar cell (DSSC) normally employing a nanoporous TiO2 photoanode draw a quite attention to meet future solar energy market demanding because its realizable low-cost property and high-efficiency achievement. Continuing efforts have been devoted to improve the performance of DSSCs. However, there are still several drawbacks need to be overcome. The major drawbacks mainly focus on the electron recombination and low-efficiency electron transport in the nanoporous TiO2 photoanodes, which significantly limit the practical application of DSSCs. Therefore, the main task of this thesis is to retard the electron recombination and to improve the electron transport efficiency in the nanoporous TiO2 photoanodes for DSSCs through interfacial and structural modification strategies.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Hamrick, Todd Robert. "Characterization of key performance parameters in dye sensitized solar cells using a designed experiment." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5817.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains v, 37 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 33-37).
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Kay, Andreas. "Solar cells based on dye-sensitized nanocrystalline TiO₂ electrodes /." Lausanne, 1994. http://library.epfl.ch/theses/?nr=1214.
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Hagberg, Daniel. "Synthesis of Organic Chromophores for Dye Sensitized Solar Cells." Doctoral thesis, KTH, Organisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10547.
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This thesis deals with development and synthesis of organic chromophores for dye sensitized solar cells. The chromophores are divided into three components; donor, linker and acceptor. The development of efficient organic chromophores for dye sensitized solar cells starts off with one new organic chromophore, D5. This chromophore consists of a triphenylamine moiety as an electron donor, a conjugated linker with a thiophene moiety and cyanoacrylic acid as an electron acceptor and anchoring group. Alternating the donor, linker or acceptor moieties independently, would give us the tool to tune the HOMO and LUMO energy levels of the chromophores. The following parts of this thesis regard this development strategy. The contributions to the HOMO and LUMO energy levels were investigated when alternating the linker moiety. Unexpected effects of the solar cell performances when increasing the linker length were revealed, however. In addition, the effect of an alternative acceptor group, rhodanine-3-acetic acid, in combination with different linker lengths was investigated. The HOMO and LUMO energy level tuning was once again successful. Electron recombination from the semiconductor to the electrolyte is probably the cause of the poor efficiencies obtained for this series of dyes. Finally, the development of functionalized triphenylamine based donors and the contributions from different substituents to the HOMO and LUMO energy levels and as insulating layers were investigated. This strategy has so far been the most successful in terms of reaching high efficiencies in the solar cell. A top overall efficiency of 7.79 % was achieved.QC 20100716
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Karlsson, Martin. "Materials Development for Solid-State Dye-Sensitized Solar Cells." Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-165458.
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The dye-sensitized solar cell (DSC) is a photovoltaic technology with the potential to efficiently and economically harvest and convert energy from the sun to electrical power. DSCs are built using abundant and low cost materials such as titanium dioxide (TiO2) and organic dye molecules. The dye molecule acts as a light absorber funneling electrons from its photo-excited state to the TiO2. A redox mediator which typical consists of iodide/tri-iodide undergoes redox reactions at the counter electrode and the oxidized dye molecule creating a circuit between the two. Solid-state versions of the DSC are also being investigated. In these devices the liquid electrolyte is exchanged with solid hole transporting material in order to both simplify the solar cell production as well as increasing the open-circuit potential and stability of the solar cell. One main draw-back, which limits the increase in conversion efficiency of solid-state DSC is the faster electron recombination dynamics between electrons in the TiO2 and holes in the solid hole transporter. Currently the highest performing liquid electrolyte DSC reaches a conversion efficiency of over 12 %, while the solid-state DSC is tailing with 7 %. Materials development is crucial for further development of the DSC technology, hopefully leading to better stability and higher efficiency. Many types of dye molecules, redox mediators as well as hole transporting materials and working electrode materials have all been tested and modified in the past in order to improve DSC performance. Significant further improvement of DSC technology requires a better understanding of the operating principle behind the DSC and the interaction between the different components. This requires advanced characterization methods for materials and solar cells. In this thesis, new materials for DSC have been developed, tested and characterized using advanced methods. Atomic layer deposition was employed to develop a new working electrodes based on the core-shell SnO2-TiO2 material. These working electrodes were successfully used in both liquid and solid-state DSC to decrease the electron recombination dynamics and increase conversion efficiencies. The molecular structure of sensitizing dyes also plays a major role in electron recombination. Thus, investigating different molecular structures of sensitizing dyes is of importance when trying to improve DSC performance. Seven new molecular dye structures based on three different chromophore units were investigated in both liquid electrolyte and solid-state DSC. For example, adding a second anchoring group on the D35 molecular structure improved the light harvesting capabilities of the dye but did not result in DSC devices with higher conversion efficiency. Increasing the bulkiness of the molecular dye structure facing away from the TiO2 surface yielded on the other hand higher both slower electron recombination and higher conversion efficiencies. The effects of oxygen on solid-state DSC using spiro-OMeTAD were also studied. The chemical oxidation of the solid-state hole transporting material was found to depend on both time and storing conditions of the complete DSC devices. Solar cells with higher conversion efficiency were found for solid-state DSC stored under ambient air conditions before measured. Finally, a novel and efficient organic tandem solar cell was demonstrated built using a solid-state DSC and a bulk heterojunction solar. The 6 % efficient tandem cell almost perfectly added the photo-potentials of the subcells together while keeping the photo-current intact.
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Caga, Noloyiso. "The characterization and electrochemistry of dye-sensitized solar cells." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016069.
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In this study a presentation of the technology behind dye-sensitized solar cells, their design as well as the role of the different parts of the cell. The characterization of the cell is divided into four sections namely: the characterization of the paste required to make the TiO2 film and its optical properties using SEM-EDX and XRD analytical techniques; Analysis of the various absorptions of three Ru-based dyes using UV-Vis spectroscopy, Photoluminescence and Fourier Transform Infra-Red spectroscopy; the characterization and the analyses of the entire cell using Electrochemical Impedance Spectroscopy. The nine cells were prepared by examining RuL2(CN)2 , RuL2(NCS)2 or N3 dye and RuL2(NCS)2 TBA+ or N719 dye. [L = 2,2'-bipyridyl-4,4'-dicarboxylic acid ;TBA = tetra-butyl ammonium] were combined with three electrolytes namely: Z–150 , AN–50 and PN–50. The Iodolyte PN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called propionitrile (PN). The Iodolyte AN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called acetonitrile (AN). The Iodolyte Z–150 is an iodide based low viscosity electrolyte with 150 mM of tri-iodide dissolved in a solvent called 3-methoxypropionitrile (MPN) and with additives such an ionic liquid, malkylbenziimidazole and guanidine thiocyanate. A solar simulator was utilized with which the standard solar irradiation can be created in laboratory conditions. The fill factors as well as overall performance efficiencies of the these cells are quite low < 1.0%,.
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Hagberg, Daniel. "Synthesis of Organic Chromophores for Dye Sensitized Solar Cells." Licentiate thesis, Stockholm : Kemi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4600.
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Louca, Rami Rafik Morgan. "Titanium dioxide nanorod solid-state dye-sensitized solar cells." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707921.
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Peltola, Timo. "Characterisation of dye-sensitized solar cells for process control." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669023.
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Dye-sensitized solar cells are a class of photovoltaics that have shown promise in producing electricity at a reasonable price. Although the processes limiting performance of the devices are quite well understood, their quantification has not been incorporated into a single consistent framework. In this study this framework, based on continuum charge transport equations, is presented and used to investigate the effectiveness of common characterisation methods. Approximate analytical solutions to the model are also derived and it is shown that these can be used to solve the device model inverse problem by fitting the solutions to impedance spectroscopy measurements. Experimental results indicate that the overall device model is a good description of the system and that it can be used to quantify different power loss mechanisms. Additionally some initial work was undertaken to formulate a charge transport model for a new class of photovoltaics called perovskite cells. The cell is modelled as a p-i-n heterojunction where the perovskite absorber is an intrinsic semiconductor sandwiched between two selective contacts. Simulations indicate that a significant built-in field drives free charges towards the contacts significantly improving charge collection.
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Sartori, André Frota. "Variação temporal do desempenho de dye-sensitized solar cells." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2645.
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Mestrado em Engenharia FísicaNeste trabalho produziu-se e estudou-se um grupo de 4 dye-sensitized solar cells (células solares activadas por corante), também conhecidas por células de Grätzel, durante um período de 9 meses a fim de se observar, caracterizar e compreender a variação do desempenho e do comportamento eléctrico e físico de cada uma delas, não só de um ponto de vista qualitativo, mas também quantitativo. Utilizou-se para tal um conjunto de técnicas de caracterização que abrangeram tanto aspectos ópticos e morfológicos (espectrofotometria e microscopia electrónica de varrimento), quanto aspectos eléctricos e difusivos (curvas -, OCVD e espectroscopia de impedância). A partir dos resultados foi possível conhecer alguns factores responsáveis pela degradação do desempenho das células ao longo do tempo, conhecimento este que será útil no aprimoramento destes dispositivos. ABSTRACT: In this work, a group of 4 dye-sensitized solar cells, also known by Grätzel cells, was produced and studied throughout 9 months, in order for the performance, electrical and physical behaviour to be observed, characterized and understood, not only from a qualitative point of view, but also quantitatively. A set of techniques, comprised of spectrophotometry, scanning electron microscopy, - curves, OCVD and impedance spectroscopy was employed to provide optical, morphological, electrical and diffusive information related to each cell. From the collected data, it was possible to figure out a few factors responsible for the observed decrease in the cells’ performance over time, a knowledge that is going to be useful in the improvement of these devices.
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Garcia, Mayo Susana. "Dye-Sensitized Solar Cells: the future of consumer electronics?" Thesis, Högskolan i Gävle, Energisystem och byggnadsteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-36993.
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Dye-sensitized solar cells (DSSCs) or Grätzel cells are electrochemical devices in where physicochemical properties of different materials are combined to obtain electric energy. These photoconversion devices have evolved from a pioneering concept of molecular photovoltaics to industrial development with confirmed record efficiencies of 14.3%. Their efficiency combined with low-cost production methods and a high aesthetic interest enables the production of DSSC products for consumer electronics market. The strengths of this technology and the fact that its drawbacks are not limiting for this application makes consumer electronics and DSSC a perfect match for the development of self-powered devices. Some companies have already spot a potential market and are currently launching different consumer electronics and other devices with embedded DSSC. This thesis provides an overview of the operation principles of DSSC and the possible routes to improve the efficiency of these devices to emerge and thrive. Additionally, improvements in efficiency, stability and manufacturing needed to be addressed in the near future for this technology are discussed and its suitability to represent a breakthrough in the market of consumer electronics. An overview of the main companies developing DSSC and current prototypes and products is included.
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Santos, Rute. "Sealing of dye-sensitized solar cells." Dissertação, 2013. http://hdl.handle.net/10216/73397.
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Wang, Chun-Ying, and 王郡瑩. "Silicon based dye-sensitized solar cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/36748917789903833577.
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碩士國立中興大學
機械工程學系所
100
This study proposes a new dye-sensitized solar cells (DSSC) structure. In this new structure, top-side illumination is adopted to replace the traditional backlight input mode. An general electrode such as a semiconductor material can be used as the photoelectrode to replace the conventional implemented transparent conductive oxides (TCO) so that the high temperature sintering induced high resistance problem can be avoided. For the fabrication of the nano-structured photoelectrode, the electroless metal deposition (EMD) was utilized for the fabrication of nanorod array on the surface of silicon, followed by the dielectrophoretic deposition of TiO2 and then the coating of dye. The nanorod array enables a fast delivery of the photo-electrons to the connection wire. A prototype of the proposed novel DSSC was fabricated. The energy conversion efficiency was measured to be 0.14%.
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Santos, Rute Marisa Rêgo dos. "Sealing of dye-sensitized solar cells." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/68535.
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Chen, Jian-Lin, and 陳建霖. "Investigation of dye-sensitized solar cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/40995552949577425196.
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Huang, Yu-Kai, and 黃煜凱. "Modeling of Dye-sensitized Solar Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/66800661630228257250.
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碩士國立臺灣大學
光電工程學研究所
101
We present a way to account optical and electrical modeling of dye-sensitized solar cells (DSSCs).The optical model is based on one-dimensional partially coherence system, in which nanoporous active layer and rough Pt electrodes was successfully modeled by transfer-matrix method. The novel feature is that the transition from incoherent to coherent is achieved by introducing a random phase to simulate the ef-fect of defects or roughness surface. The electrical model is based on continuity and transport equations for electrons, iodide and triiodide ions. In recombination mecha-nism, exponential distribution of trap states in TiO2 and Gaussian distributions of en-ergy levels in the electrolyte within active layer are assumed in modeling, according to Shockley-Read-Hall statistics and Marcus-Gerischer electron transfer theory. These theory are used to describe the process of electron transfer . In addition, the effect of the active layer thickness on the DSSC performance is also presented. It was found that the open-circuit voltage decreased with increasing electrode thickness. The optimal electrode thickness for the highest power conversion efficiency was decided by higher or lower dye loading on nano-particle. Finally, Our simulation results are compared with the published experimental data like cur-rent-voltage characteristics and light intensity dependence of open circuit. In particular, the relation between open-voltage and light intensities indicate that the recombination occurred mainly through TiO2 /electrolyte interface under high illumination intensities and recombination via TCO/electrolyte interface is dominant under low illumination intensities. However, the demarcation of two different recombination mechanism is depend on characteristic of blocking layer. In summary, a method for calculating the optical response of multilayer systems is presented, which can deal with nanoporous active layer and rough Pt electrodes of DSSC structure. Also, the electrical model is described in detail, and numerical results are presented, which demonstrate the feasibility of the model. The influence of the most important material parameters on the cell performance are illustrated.
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Santos, Rute Marisa Rêgo dos. "Sealing of dye-sensitized solar cells." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/68535.
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Dwivedi, Garima. "Studies on dye-sensitized solar cells." Thesis, 2017. http://localhost:8080/xmlui/handle/12345678/7452.
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Huang, Wei-Gang, and 黃唯罡. "Lifetime Study of Dye Sensitized Solar Cells." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/42261321884246425233.
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碩士國立聯合大學
光電工程學系碩士班
104
In the thesis, we discuss the performance change of the DSSCs (Dye Sensitized Solar Cells) versus time. It is found that the open-circuit voltage (VOC) increases, short-circuit current (JSC) decreases, while fill factor (FF) increase with the storage time of the devices. We also test and analyze the working electrode, photosensitizer (N719 dye), electrolyte and counter electrode separately to find the cause of the performance change. According to the experimental results, we find the performance of DSSCs decays because of : (1) the oxidation of working electrode, (2) desorption and degradation of dye under illumination, (3) the loss of electrolyte, and (4) the solvent volatilization of electrolyte. The increase of VOC is contributed to the irreversible change of oxidation potential of the TiO2 working electrode. The decrease of JSC is caused by the degradation and desorption of dye molecules under illumination, which result in the decay of the absorption and is also irreversible. Furthermore, both the loss of electrolyte and the solvent volatilization of electrolyte result in the decrease of JSC. However, they can be recovered by re-injecting electrolyte and the solvent. Finally, optimize the performance of the DSSCs and suggest the manufacturing process so that the devices having higher stability and longer lifetime can be obtained.
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Chang, Yen-Cheng, and 張晏禎. "Porphyrin Dimers for Dye-sensitized Solar Cells." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/43f7c5.
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碩士國立暨南國際大學
應用化學系
102
In this thesis, a series of ethynyl-linked, push-pull porphyrin dimers were synthesized and studied for dye-sensitized solar cells by Sonogashira cross-coupling method. These porphyrin dimers (denoted as LDD1~LDD6) bear a 4-ethynyl-N,N-dimethylaniline substituent as the electron-donating group, ethynyl goups as the π-bridges, and 4-ethynyl-benzoic acid as the anchoring group. Two versions of dimers were prepared : Zn-Zn and zinc-free-base (Zn-fb) dimers. In order to increase light-harvesting capability in the near-IR region, we also introduced anthracene and tetracene groups into the dimers. Electrochemical data show that the reduction potentials of the anthracene- and tetracene- modified porphyrin dimers are positive-shifted from those of the dimers without acenes, demonstrating the effect of extended π-conjugation. Both of the UV-Visible absorption spectra and fluorescence emission spectra show strong bathochromic shifts of the Zn-fb porphyrin dimers. The PCE values of LDD1~LDD6 DSSC show a trend of LDD1 (8.6%) > LDD3 (5.98%) > LDD2 (5.22%) > LDD5 (2.26%) > LDD4 (2.16%) > LDD6 (0.78%). Significantly, co-sensitizing LDD1 with LD14 gives rise to η = 10.4% of the DSSC. For the solid-state dye-sensitized solar cells, these dyes showed efficiencies in the range of 0.63%~1.63%.
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Anwar, Hafeez. "Precious Metal-free Dye-sensitized Solar Cells." 2013. http://hdl.handle.net/10222/42686.
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Exploring new technologies that can meet the world’s energy demands in an efficient and clean manner is critically important due to the depletion of natural resources and environmental concerns. Dye-sensitized solar cells (DSSCs) are low-cost and clean technology options that use solar energy efficiently and are being intensively studied. How to further reduce the cost of this technology while enhancing device performance is one of the demanding issues for large scale application and commercialization of DSSCs. In this research dissertation, four main contributions are made in this regard with the motivation to reduce further cost of DSSC technology. Firstly, ~10% efficiencies were achieved after developing understanding of key concepts and procedures involved in DSSCs fabrication. These efficiencies were achieved after step-by-step modifications in the DSSC design. Secondly, carbon nanotubes (CNTs) were successfully employed as an alternative to Pt in the counter electrodes of DSSCs. DSSCs fabricated with CNTs were ~86% as efficient as Pt-based cells. Non-aligned CNTs were successfully grown using four different CVD methods and finally, multi-walled vertically aligned CNTs (MW-VACNTs) were synthesized using water-assisted chemical vapor deposition (WA-CVD). Thirdly, carbon derived from pyrolysis of nanocrystalline cellulose (NCC) was successfully employed in counter electrodes of DSSCs instead of Pt. DSSCs with NCC were ~58% as efficient as Pt-based DSSCs. Fourthly, novel organic metal-free dyes were designed and employed instead of commonly used Ru-based dyes. DSSCs with these novel sensitizers were ~62% as efficient as those using the conventional Ru-based dyes. Characterization techniques including current-voltage measurements, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetery (CV), thermogravimetric analysis (TGA), small angle x-ray scattering (SAXS), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) were used.