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Sun, Haiyan. "Metal oxide layer in organic solar cells." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-147159.
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Dharmadasa, Ruvini. "Studies of composite metal oxide based ETA solar cells." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9117.
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The drive to produce low cost and efficient solar cells to replace solid state silicon cells has led to the rapid growth of nanotechnology in the PV sector. The extremely thin absorber (ETA) layer solar cell is a device that relies on the use of nanostructured anodes. The very high surface area of the metal oxides enhances the efficiency of the devices by increasing light harvesting in the cell. TiO2 has been the most common material of choice in these cells. However, alternative materials such as composite electrodes ZnO/TiO2, ZnO/SnO2, ZnO/Al2O3 have been considered. These systems also have the ability to improve charge carrier separation and broaden their photoresponse region. In addition to selecting materials with the correct energetics, the morphology of the metal oxide particles plays an important role in these devices. The ability to manipulate the shape, size, and surface to volume ratio of these oxides is critical in influencing the materials chemical, electronic and optical properties. In this thesis the fabrication of composite (ZnO,SnO2) electrodes by aerosol assisted chemical vapor deposition (AACVD) was investigated. By simply varying the Zn:Sn ratio in the precursor solution, a range of (ZnO,SnO2) composite materials along with single phase ZnO and SnO2 has been fabricated. It has been found that the morphology of the deposited electrodes is highly dependent on the Zn content with electrodes with morphologies ranging from nanoplates, to nanocolumns, to highly compact structures have been deposited. The dependence of the Zn content in the deposition solution on the photoelectrochemical (PEC), optoelectronic, photon to electron conversion efficiency (APCE) and photovoltaic characterization was investigated. ETA solar cells with FTO/(ZnO,SnO2)/In2S3/PbS/PEDOT:PSS/Cgraphite/FTO structures were successfully fabricated to demonstrate the suitability of (ZnO,SnO2) anodes in these devices. This work has shown that AACVD is a useful technique for engineering the properties of semiconducting electrodes for PV applications.
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Zhu, Le. "Development of metal oxide solar cells through numerical modeling." Thesis, University of Bolton, 2012. http://ubir.bolton.ac.uk/810/.
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Photovoltaic (PV) devices become increasingly important due to the foreseeable energy crisis, limitation in natural fossil fuel resources and associated green-house effect caused by carbon consumption. At present, silicon-based solar cells dominate the photovoltaic market owing to the well-established microelectronics industry which provides high quality Si-materials and reliable fabrication processes. However ever increased demand for photovoltaic devices with better energy conversion efficiency at low cost drives researchers round the world to search for cheaper materials, low-cost processing, and thinner or more efficient device structures. Therefore, new materials and structures are desired to improve the performance/price ratio to make it more competitive to traditional energy. Metal Oxide (MO) semiconductors are one group of the new low cost materials with great potential for PV application due to their abundance and wide selections of properties. However, the development of MO solar cells is very limited so far mostly due to the poor materials and poor understanding of the materials and devices. This research conducts a systematic numerical investigation on MO thin film solar cells. Various MO semiconductors are used to explore different structures and combinations for solar cells; and the effects of material properties and structures are optimised for the best performances. For the ideal cases, it is found that a TiO2/CuO hetero-junction solar cell shows a conversion efficiency of ~16% with the CuO film thickness only 1.5μm. When a back surface field layer, such as Cu2O, is added at the back of this device, the open circuit voltage (VOC) can be improved by 70% without sacrificing short circuit current, resulting in a conversion efficiency of ~28%, increased by ~70% as compared to the two-layered structure. This is close to the theoretical maximum efficiency of silicon single junction solar cell, which requires a 200~400μm thickness film. Modelling also shows the alternative Schottky barrier type MO semiconductor solar cells can perform well. For an ideal Metal/CuO Schottky barrier solar cell, the conversion efficiency could be as high as ~17%, better than the TiO2/CuO hetero-junction solar cell. The effects of defects and interface states are then considered for more realistic cases as there exists vast amount of defects mostly due to oxygen/metal vacancies/interstitials in the films, and vast amount of interface states due to the large lattice mismatch of the two materials used. All defects and interface states in the solar cell layers, hetero-junction interfaces and metal/semiconductor contacts are found detrimental to the cells. For example, if the defect concentration in the CuO layer in TiO2/CuO structure is compatible to the acceptor concentration of 1x1016cm-3, the cell efficiency would be reduced dramatically to 7%. With defect concentration even as low as 1x1013cm-3, the significant VOC improvements in the TiO2/CuO/Cu2O would be reduced to an ignorable value. For interface states, they capture and recombine both electrons and hols passing through the hetero-junction interface, leading to deteriorated performance. The simulation shows that the interface states have a detrimental effect on the performance if its density is higher than 1012cm-2. However it was found that by increasing the difference of doping concentration in p-n junctions, the interface state effect minimized significantly. Furthermore, it is found the optical reflection at hetero-junction interface may induce a serious conversion efficiency loss, if the n-type semiconductors and p-type semiconductors have very different refractive indices. For some MO devices such as TiO2/CuO and ZnO/Cu2O, the reflection rate is around 5%, while for other material systems such as ZnO/Si, or ITO/Ge, the interfacial optical reflection may reach 10~30%, resulting in an efficiency loss by ~10%. It is also found that the interfacial reflection should be calculated through experimental data of refractive index at each photon frequency, rather than the dielectric constant. Otherwise, huge error may be introduced to the simulation results.
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Katz, Jordan E. Okumura Mitchio Lewis Nathan Saul. "Metal oxide-based photoelectrochemical cells for solar energy conversion /." Diss., Pasadena, Calif. : California Institute of Technology, 2008. http://resolver.caltech.edu/CaltechETD:etd-10192007-190231.
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Pachoumi, Olympia. "Metal oxide/organic interface investigations for photovoltaic devices." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/246263.
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This thesis outlines investigations of metal oxide/organic interfaces in photo-voltaic devices. It focuses on device instabilities originating from the metal oxide layer surface sensitivity and it presents suggested mechanisms behind these in- stabilities. A simple sol-gel solution deposition technique for the fabrication of stable and highly performing transparent conducting mixed metal oxides (ZnMO) is presented. It is demonstrated that the use of amorphous, mixed metal oxides allows improving the performance and stability of interfacial charge extraction layers for organic solar cells. Two novel ternary metal oxides, zinc-strontrium- oxide (ZnSrO) and zinc-barium-oxide (ZnBaO), were fabricated and their use as electron extraction layers in inverted organic photovoltaics is investigated. We show that using these ternary oxides can lead to superior devices by: prevent- ing a dipole forming between the oxide and the active organic layer in a model ZnMO/P3HT:PCBM OPV as well as lead to improved surface coverage by a self assembled monolayer and promote a significantly improved charge separation efficiency in a ZnMO/P3HT hybrid device. Additionally a spectroscopic technique allowing a versatility of characterisa- tion for long-term stability investigations of organic solar cells is reported. A device instability under broadband light exposure in vacuum conditions for an inverted ZnSrO/PTB7:PC71BM OPV is observed. Direct spectroscopic evidence and electrical characterisation indicate the formation of the PC71BM radical an- ion associated with a loss in device performance. A charge transfer mechanism between a heavily doped oxide layer and the organic layers is suggested and dis- cussed.
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Bhosale, R. K. "Engineered metal oxide and chalcogenide nanomaterials for sensitized solar cells and solar photoelectrochemical water splitting." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2015. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2038.
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Willis, Richard Lance. "Functional properties of nanocrystalline metal oxide films for dye sensitised solar cells." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398946.
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Rattanavoravipa, Thitima. "Studies on surface modification of nanostructured metal oxide for hybrid solar cells." Kyoto University, 2009. http://hdl.handle.net/2433/126414.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第14965号
エネ博第208号
新制||エネ||46(附属図書館)
27403
UT51-2009-M879
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)准教授 佐川 尚, 教授 八尾 健, 教授 萩原 理加
学位規則第4条第1項該当
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Berhe, Seare Ahferom. "Acceptor-sensitizers for Nanostructured Oxide Semiconductor in Excitonic Solar Cells." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699927/.
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Organic dyes are examined in photoelectrochemical systems wherein they engage in thermal (rather than photoexcited) electron donation into metal oxide semiconductors. These studies are intended to elucidate fundamental parameters of electron transfer in photoelectrochemical cells. Development of novel methods for the structure/property tuning of electroactive dyes and the preparation of nanostructured semiconductors have also been discovered in the course of the presented work. Acceptor sensitized polymer oxide solar cell devices were assembled and the impact of the acceptor dyes were studied. The optoelectronic tuning of boron-chelated azadipyrromethene dyes has been explored by the substitution of carbon substituents in place of fluoride atoms at boron. Stability of singlet exited state and level of reduction potential of these series of aza-BODIPY coumpounds were studied in order to employ them as electron-accepting sensitizers in solid state dye sensitized solar cells.
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Haynes, Keith M. "Molecules and Materials for Excitonic Solar Cells Using P-type Metal Oxide Semiconductors." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804970/.
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This dissertation has two intersecting foci; firstly, the discovery of a new methodology for the growth of high surface area cuprous oxide (Cu2O) substrates. Secondly, the synthesis and characterization of electron-accepting molecules, and their incorporation into excitonic solar cells (XSCs) using the Cu2O substrates as electrodes. Increasing the surface area of the semiconductor creates more locations for charge transfer to occur thus increasing the overall efficiency of the device. Zinc oxide (ZnO) has been widely studied, and can be easily grown into many different films with high surface area morphologies. The ZnO films serve as sacrificial templates that allow us to electrochemically grow new semiconductors with the same high surface area morphologies but composed of a material having more desirable electronic properties. A polymer can be applied over the surface of the ZnO nanorod films before etching the ZnO with a weak acid, thereby leaving a polymer nanopore membrane. Cathodic electrodeposition of Cu2O into the membrane nanopores gives Cu2O nanorods. Electron-accepting dyes are designed with tethers that allow for direct attachment to metal oxide semiconductors. After soaking, the semiconductor is coated with a monolayer of a dye and then the coated semiconductor films were made into various dye-sensitized solar cells (DSCs). These cells were studied to determine the electron transport properties at the semiconductor/sensitizer/electrolyte interface.
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Labanti, Chiara. "Electronic properties of transition metal oxide layers for applications in organic solar cells." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15984/.
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Gli Ossidi di Metalli di Transizione, come quelli di Molibdeno e di Titanio, sono materiali molto promettenti per lo sviluppo di applicazioni per il trasporto di carica nella fabbricazione di celle solari.
Questa tesi presenta un lavoro realizzato tra il Dipartimento di Fisica e Astronomia dell'Università di Bologna e l'Istituto delle NanoScienze di Parigi della Sorbona - Paris 6 in collaborazione con la Southern Denmark University, che mira a comprendere e modificare le proprietà di tali ossidi per il miglioramento del trasporto di elettroni e lacune in film sottili.
Il progetto di ricerca è stato portato a termine ricorrendo a varie tecniche di caratterizzazione strutturale, come la Microscopia a Forza Atomica (AFM), elettrica e chimica, tra cui la Microscopia Kelvin Probe (KPFM), la Spettroscopia di Fotoemissione a Raggi X e Ultravioletti (XPS/UPS) e la Microscopia a Fotoemissione di Elettroni a Raggi X (XPEEM) realizzata presso la sorgente di sincrotrone SOLEIL di Saint-Aubin (Francia).
I principali risultati di questo studio includono l'identificazione dell'evoluzione della superficie con la crescita di grani per l'ossido di molibdeno su silicio, la stabilità degli ossidi di molibdeno e titanio su Ossido di Indio e Stagno (ITO) dedotta dal minor numero di aggregati visibili nelle mappe AFM, l'aumento della funzione lavoro quando i materiali sono sottoposti a cicli di riscaldamento (annealing) fino a 450°C e l'interessante comparsa di domini di policristalliti sulla superficie dell'ossido di titanio ad alta temperatura.
Differenti analisi con esposizione a radiazioni hanno permesso di investigare gli effetti di luce ultravioletta e raggi X sugli ossidi e di identificare la tecnica di deposizione e le caratteristiche dei materiali più adatte per ridurre la degradazione delle proprietà elettriche causate dalla luce.
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Sun, Haiyan [Verfasser], and Lukas [Akademischer Betreuer] Schmidt-Mende. "Metal oxide layer in organic solar cells / Haiyan Sun. Betreuer: Lukas Schmidt-Mende." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1025224418/34.
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Wu, Zhenghui. "Impact of metal oxide/bulk-heterojunction interface on performance of organic solar cells." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/159.
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Organic photovoltaics have shown much promise as an alternative photovoltaic technology for application in low-cost, large-scale and flexible solar cells. The application of metal oxides in organic solar cells (OSCs) and the impact of the properties of metal oxide/organic hetero-interfaces on cell performance have attracted a lot of attention. The metal oxide/organic interfaces have a crucial impact on interfacial charge transfer, charge collection and the overall device performance. This thesis is aimed at clarifying the principal interfacial phenomena occurring at the metal oxide/organic hetero-interfaces as well as effective engineering of those interfacial properties in OSCs. Photo-generated electrons and holes undergo different recombination processes, e.g., bimolecular recombination and trap-assisted recombination, before being collected by the electrodes in OSCs. Light intensity-dependent current densityvoltage (JV) characteristics of OSCs were analyzed to study the effect of recombination on charge collection efficiency. Effect of metal oxide/organic hetero-interfaces on charge transfers at organic/electrode interface was analyzed using transient photocurrent (TPC) measurements. Light intensity-dependent JV characteristics and TPC characteristics were applied to explore the charge recombination dynamics in OSCs with a metal oxide interlayer. This project concentrated on an in-depth investigation of the physics and the interface phenomena such as interfacial exciton dissociation, charge recombination processes, charge collection and interface engineering for high performing OSCs. The fundamentals about light intensity-dependent J-V characteristics for OSCs were summarized. The relationship between the charge recombination dynamics and light intensity-dependent J-V characteristics in OSCs were developed. Light intensity-dependent JSC, VOC and FF in OSCs made with different bulk-heterojunction (BHJ) systems of PTB7:PC70BM, PTB7-Th:PC70BM and PNB4:PC70BM were investigated. It is found that bimolecular recombination is the most prominent factor limiting the performance of OSCs. For freshly made OSCs fabricated based on the commercial polymers, e.g. PTB7 & PTB7-Th, and the new polymer PNB4 synthesized in-house, the trap-assisted charge recombination process in the BHJ active layer plays a relatively small role. This suggests that reducing the bimolecular recombination in OSCs through selecting proper materials and device structures is crucial for enhancing the power conversion efficiency (PCE) of OCSs. In this work, device structures which enable reducing bimolecular recombination in OSCs were investigated. The effect of ZnO interlayer at the interface between BHJ and Al cathode on the performance of PTB7:PC71BM based OSCs was studied by a combination of theoretical simulation and experimental characterization techniques, e.g., using light intensity-dependent JV characteristic and TPC measurements etc. It shows that ZnO interlayer has a profound effect on the performance of the PTB7:PC70BM-based OSCs, although it does not have a significant influence on the maximum absorptance in the active layer. The origin of the improvement in the cell performance is associated with the efficient charge collection due to the favorable exciton dissociation at the electrode/active layer interface. It is shown that the presence of the ZnO interlayer allows using a thinner active layer without moderating the absorption in the optically optimized control OSCs without the ZnO interlayer. OSCs with a ~10 nm thick ZnO interlayer are found to be favorable for the efficient charge collection, and thereby improving the cell performance. The TPC measurements also reveal that the dissociation of excitons at the metal/organic interface of regular OSCs hinders the electron collection. The unfavorable interfacial exciton dissociation can be removed by interposing a ZnO interlayer at the Al/organic interface, thus bimolecular recombination at the electrode/active layer interface can be reduced for improving the charge collection efficiency. PCE of the OSCs using ZnO interlayer was 6.5%, which is about 20% higher than a control cell (5.4%), having an identical device configuration without a ZnO interlayer. Solution-processed anode interlayer, a mixture of solution-processed MoOX and PEDOT:PSS, was adopted for application in inverted PTB7:PC71BM-based OSCs. The ratio of MoOX to PEDOT:PSS in the mixed solution was optimized for achieving the best cell performance. A PCE of 7.4% was obtained for OSCs with an optimal MoOX-PEDOT:PSS based interlayer, interposed between the BHJ active layer and Ag anode, which means 10% enhancement over the PCE of control cell made with an evaporated MoOX interlayer. Light intensity-dependent JV characteristics implied that the bimolecular recombination in OSCs with a MoOX-PEDOT:PSS interlayer was reduced. TPC measurements showed that the favorable exciton dissociation occurs at the organic/MoOX interface for the inverted OSCs. The favorable interfacial exciton dissociation generates an electrical field within a very small space near the interface, contributing significant additional photocurrent when the effective bias across the active layer in the OSCs is low, and thereby assisting in an efficient charge collection at the organic/electrode interface. In addition to the improvement in the cell performance, the solution-processed MoOX-PEDOT:PSS interlayer does not require a post-annealing treatment, which is beneficial for application in solution-processed tandem and flexible OSCs.
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Bowers, Norman Mark. "Metal oxide nanocrystalline thin films as buffer layers in organic/ hybrid solar cells." University of Western Cape, 2019. http://hdl.handle.net/11394/7698.
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>Magister Scientiae - MScWithout reverting to encapsulation, organic bulk - heterojunction solar cells can be protected from the oxidation of the highly reactive low work function cathode metal electrode, by the deposition of metal oxide buffer layers onto an indium-tin oxide (ITO) substrate. The zinc-oxide (ZnO) or titanium dioxide (TiO2) layer can serve as an electron collecting contact. In such a case the ordering of layer deposition is inverted from the traditional layer sequencing, using an additional effect of the metal oxide layer acting as a hole blocking contact
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SCIRE', Daniele. "TRANSITION METAL OXIDES AS SELECTIVE CONTACTS FOR C-SI SOLAR CELLS." Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/514988.
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Ip, Chung Man. "Theoretical studies in dye-sensitized solar cells and photo-catalysis at metal oxide interfaces." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/87995/.
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In this thesis we present theoretical and computational studies for the p-type and n-type dye-sensitized solar cells (DSSCs), and the photo-catalytic reduction of carbon dioxide to generate methane. For p-type DSSCs, we computed the hole injection and recombination rate at the semiconductor-dye (NiO-C343) interface based on theories applied previously for electron injection and recombination in n-type DSSCs, derived from Fermi golden rule and non-adiabatic charge transfer theory. Our analysis showed that the faster recombination in p-type in comparison to n-type was due to difference in Franck-Condon factor of the relevant transitions. For n-type DSSCs, we devised a statistical model based on the electronic structural properties of dyes for predicting the efficiency of this device with confidence when a new dye was employed. The approach for constructing the model was QSAR-like and involved examining correlations between the efficiency of the device and a number of predictors that were properties of the dye. We also quantified the donor-π-acceptor (D-π-A) character of dyes and showed statistically that increasing the strength of this character was ineffective for improving the efficiency of n-type DSSCs. For photo-catalytic reduction of carbon dioxide to produce methane, we studied with DFT calculations three competing reaction mechanisms on TiO2 anatase(101) proposed in literature on the basis of experimentally observed reaction intermediates. By comparing the thermodynamics of mechanisms we showed that the formaldehyde pathway was the most favorable reaction mechanism. The computational methodology employed was useful for testing mechanistic hypotheses for reactions on the surface of solid catalysts.
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Lima, Francisco Anderson de Sousa. "Application of transition-metal-oxide-based nanostructured thin films on third generation solar cells." reponame:Repositório Institucional da UFC, 2015. http://www.repositorio.ufc.br/handle/riufc/14584.
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LIMA, F. A. S. Application of transition-metal-oxide-based nanostructured thin films on third generation solar cells. 2015. 225 f. Tese (Doutorado em Ciência de Materiais) – Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2015.Submitted by Marlene Sousa (mmarlene@ufc.br) on 2015-12-17T12:45:41Z No. of bitstreams: 1 2015_tese_faslima.pdf: 24015209 bytes, checksum: a66470eb7a55b6b3c2a5e8544c6d4d32 (MD5)
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One of the greatest challenges of our time is to devise means to provide energy in a sustainable way to attend an exponentially growing demand. The energy demand is expected to grow 56% by 2040. In this context, the use of clean and sustainable sources of energy is imperative. Among these sources, solar energy is the only one which can meet the total world energy requirement even considering such large growth in demand. The solar power incident on the Earth's surface every second is equivalent to 4 trillion 100-watt light bulbs. Photovoltaic solar cells are one of several ways to harness solar energy. These cells convert solar energy directly into electricity. Commercial photovoltaic devices are already a reality, but their share of the world energy matrix is still quite small, mainly due to the high costs. Next generation photovoltaics open a number of new possibilities for photovoltaic energy applications that can potentially decrease the overall cost of energy production. Transition metal semiconductor oxides are promising materials that can be produced by low cost methods and o er interesting new features. The use of these materials in next generation photovoltaics is therefore a very promising and interesting application. In this thesis work zinc, titanium and vanadium oxides were used in next generation solar cells. Thin lms of zinc oxide were synthesized by the low cost and environmentally friendly techniques of electrodeposition and hydrothermal synthesis and applied as working electrodes in highly e cient dye sensitized solar cells (DSSCs). The lms were characterized by structural and optical techniques while the cells were tested by current vs: voltage and quantum e ciency measurements. The e ciencies of these cells were as high as 2.27% using ZnO thin lms without any post deposition treatment. Moreover, natural dyes extracted from plants of northeastern Brazil were applied as sensitizers in DSSCs assembled with commercial available TiO 2 as working electrode. The natural dyes were extracted employing very simple methods and were characterized by XPS and UPS techniques. Their band alignments were shown to be compatible with the TiO 2 as well as with the mediator electrolyte. The e ciency of DSSCs sensitized with natural dyes were as high as 1.33%. Finally, water based V 2 O 5 was used as hole transport medium (HTM) in conventional organic solar cells (OSCs) and ITO-free, plastic OSCs. The results obtained with V 2 O 5 were compared with the results obtained from cells assembled with PEDOT:PSS, which is the most used HTM. This comparison showed that the use of V 2 O 5 as HTM can lead to more e cient OSCs. The stability of these devices were evaluated by tests applying the ISOS standards ISOS-D-1, ISOS-L-1 and ISOS-O-1. A UV- lter and a protective graphene oxide (GO) layer were employed seeking to improve the stability of OSCs. The combination of both UV- lter and GO protective layer was shown to be the most e ective way to improve the stability of these devices
Um dos maiores desa os do nosso tempo e desenvolver formas para fornecer energia de forma sustent avel para atender uma demanda que cresce exponencialmente e que dever a crescer 56% at e 2040. Neste contexto, o uso de fontes limpas e sustent aveis de energia e um imperativo. Entre essas fontes, a energia solar e a unico que pode satisfazer a ne- cessidade total de energia do mundo, mesmo considerando o crescimento na demanda. A pot^encia solar incidente na superf cie da Terra a cada segundo e equivalente a 4 trilh~oes de l^ampadas de 100 watts. C elulas solares fotovoltaicas s~ao uma das v arias maneiras de aproveitar a energia solar, convertendo-a diretamente em eletricidade. Dispositivos com- erciais fotovoltaicos j a s~ao uma realidade, mas a sua participa c~ao na matriz energ etica mundial ainda e muito pequena, principalmente devido aos seus custos elevados. C elulas fotovoltaicas de nova gera c~ao abrem uma s erie de novas possibilidades para aplica c~oes de energia fotovoltaica que pode diminuir o custo total de produ c~ao de energia. Oxidos semicondutores de metais de transi c~ao s~ao materiais promissores que podem ser produzi- dos atrav es de m etodos de baixo custo e que possuem caracter sticas interessantes. Por conseguinte, o uso destes materiais em energia fotovoltaica de pr oxima gera c~ao se apre- senta com uma aplica c~ao promissora. Nesta tese de doutorado oxidos de zinco, tit^anio e van adio foram utilizados em c elulas solares de pr oxima gera c~ao. Filmes nos de oxido de zinco foram sintetizados por eletrodeposi c~ao e s ntese hidrot ermica. Os lmes foram apli- cados como eletrodos de trabalho em c elulas solares sensibilizadas por corante (DSSCS) altamente e cientes. Os lmes foram caracterizados por t ecnicas estruturais e oticas en- quanto que as c elulas foram testadas por medidas de corrente vs: voltagem e de e ci^encia qu^antica. A e ci^encia dessas c elulas atingiu 2,27% utilizando lmes nos de ZnO sem qualquer tratamento p os-deposi c~ao. Al em disso, corantes naturais extra dos de plan- tas do nordeste do Brasil foram aplicados como sensibilizadores em DSSCs montadas com TiO 2 comercial utilizado como eletrodo de trabalho. Os corantes naturais foram extra das empregando m etodos simples e foram caracterizados por espectroscopia de fotoel etrons excitados por raios X e por radia c~ao ultravioleta, XPS e UPS respectivamente. Seus alin- hamentos de banda se mostraram compat veis com o TiO 2 e com o eletrodo de regenera c~ao. A e ci^encia das DSSCs sensibilizadas com corantes naturais chegou a 1,33%. Finalmente, V 2 O 5 a base de agua foi usado como material transportador de buracos (HTM) em c elulas solares org^anicas (OSCs) convencionais e OSCs de pl astico constru das sem ITO. Os re- sultados obtidos com V 2 O 5 foram comparados com os resultados de c elulas constru das com PEDOT:PSS, que e o HTM mais utilizado. Esta compara c~ao revelou que o uso de V 2 O 5 como HTM pode levar a OSCs mais e cientes. A estabilidade destes dispositivos foi avaliada por testes aplicando os padr~oes ISOS-D-1, ISOS-L-1 e ISOS-O-1. O uso de ltros ultravioleta e de uma camada protetora de oxido de grafeno reduzido foi testado com o intuito de melhorar a estabilidade desses dispositivos. O uso de uma combina c~ao de ambos se mostrou a forma mais efetiva de melhorar a estabilidade das OSCs
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Sporar, Daniel. "Sputter Deposition of Iron Oxide and Tin Oxide Based Films and the Fabrication of Metal Alloy Based Electrodes for Solar Hydrogen Production." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1183481021.
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Thesis (M.S.Ch.E.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science degree in Chemical Engineering." Bibliography: leaves 72-77.
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Yip, Cho-tung, and 葉佐東. "Effect of morphologies and electronic properties of metal oxide nanostructure layer on dye sensitized solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43759452.
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Yip, Cho-tung. "Effect of morphologies and electronic properties of metal oxide nanostructure layer on dye sensitized solar cells." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43759452.
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Fu, Qiang. "Advanced numerical characterization of silicon with defect by nanoindentation." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/54621/1/Qiang_Fu_Thesis.pdf.
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Nano silicon is widely used as the essential element of complementary metal–oxide–semiconductor (CMOS) and solar cells. It is recognized that today, large portion of world economy is built on electronics products and related services. Due to the accessible fossil fuel running out quickly, there are increasing numbers of researches on the nano silicon solar cells.
The further improvement of higher performance nano silicon components requires characterizing the material properties of nano silicon. Specially, when the manufacturing process scales down to the nano level, the advanced components become more and more sensitive to the various defects induced by the manufacturing process.
It is known that defects in mono-crystalline silicon have significant influence on its properties under nanoindentation. However, the cost involved in the practical nanoindentation as well as the complexity of preparing the specimen with controlled defects slow down the further research on mechanical characterization of defected silicon by experiment. Therefore, in current study, the molecular dynamics (MD) simulations are employed to investigate the mono-crystalline silicon properties with different pre-existing defects, especially cavities, under nanoindentation.
Parametric studies including specimen size and loading rate, are firstly conducted to optimize computational efficiency. The optimized testing parameters are utilized for all simulation in defects study. Based on the validated model, different pre-existing defects are introduced to the silicon substrate, and then a group of nanoindentation simulations of these defected substrates are carried out. The simulation results are carefully investigated and compared with the perfect Silicon substrate which used as benchmark. It is found that pre-existing cavities in the silicon substrate obviously influence the mechanical properties. Furthermore, pre-existing cavities can absorb part of the strain energy during loading, and then release during unloading, which possibly causes less plastic deformation to the substrate. However, when the pre-existing cavities is close enough to the deformation zone or big enough to exceed the bearable stress of the crystal structure around the spherical cavity, the larger plastic deformation occurs which leads the collapse of the structure. Meanwhile, the influence exerted on the mechanical properties of silicon substrate depends on the location and size of the cavity. Substrate with larger cavity size or closer cavity position to the top surface, usually exhibits larger reduction on Young’s modulus and hardness.
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Ladan, Muhammad Bello. "Application of vertically aligned arrays of metal-oxide nanowires in heterojunction photovoltaics." University of the Western Cape, 2020. http://hdl.handle.net/11394/7915.
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Philosophiae Doctor - PhDThe commercial need to improve the performance of low-cost organic solar cells has led to the idea for this research. The study discusses the synthesis of one dimensional TiO2 and ZnO nanowire arrays synthesised using a hydrothermal autoclave method and their application in bulk heterojunction inverted organic solar cells. Previous literature has shown that the precise manipulation, positioning and assembly of 1D nanostructures remain one of the greatest challenges in the field of nanotechnology, with much of the difficulty arising primarily from the lack of size and scale of the materials as well as the inability to visualise the nanostructures. In particular, one dimensional metal-oxides such as TiO2, ZnO and Fe2O3 have emerged as attractive alternatives to traditional semiconductor structures such as Si and GaAs as they are simple and inexpensive to manufacture, with research showing that application of ZnO nano-cones yield efficiencies of 8.4%, which is very attractive given the scope that exists in optimising the metal-oxide architecture. Much is still to be learned from the precise structural features of these materials and their influence on device performance. In this regard, this work largely focuses on this aspect of metal-oxide nanowires prior their application in organic solar cells.
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Möllmann, Alexander [Verfasser]. "Nanostructured Metal Oxide Thin Films as Electron Transport Material for Inorganic-Organic Hybrid Perovskite Solar Cells / Alexander Möllmann." München : Verlag Dr. Hut, 2020. http://d-nb.info/1219478067/34.
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Zhu, Zhaozhao, and Zhaozhao Zhu. "Emerging Materials for Transparent Conductive Electrodes and Their Applications in Photovoltaics." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/623062.
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Clean and affordable energy, especially solar energy, is becoming more and more important as our annual total energy consumption keeps rising. However, to make solar energy more affordable and accessible, the cost for fabrication, transportation and assembly of all components need to be reduced. As a crucial component for solar cells, transparent conductive electrode (TCE) can determine the cost and performance. A light weight, easy-to-fabricate and cost-effective new generation TCE is thus needed. While indium-doped tin oxide (ITO) has been the most widely used material for commercial applications as TCEs, its cost has gone up due to the limited global supply of indium. This is not only due to the scarcity of the element itself, but also the massive production of various opto-electronic devices such as TVs, smartphones and tablets. In order to reduce the cost for fabricating large area solar cells, substitute materials for ITO should be developed. These materials should have similar optical transmittance in the visible wavelength range, as well as similar electrical conductivity (sheet resistance) to ITO. This work starts with synthesizing ITO-replacing nano-materials, such as copper nanowires (CuNWs), derivative zinc oxide (ZnO) thin films, reduced graphene oxide (rGO) and so on. Further, we applied various deposition techniques, including spin-coating, spray-coating, Mayer-rod coating, filtration and transferring, to coat transparent substrates with these materials in order to fabricate TCEs. We characterize these materials and analyze their electrical/optical properties as TCEs. Additionally, these fabricated single-material-based TCEs were tested in various lab conditions, and their shortcomings (instability, rigidity, etc.) were highlighted. In order to address these issues, we hybridized the different materials to combine their strengths and compared the properties to single-material based TCEs. The multiple hybridized TCEs have comparable optical/electrical metrics to ITO. The doped-ZnO TCEs exhibit high optical transmittance over 90% in the visible range and low sheet resistance under 200Ω/sq. For CuNW-based composite electrodes, ~ 85% optical transmittance and ~ 25Ω/sq were observed. Meanwhile, the hybridization of materials adds additional features such as flexibility or resistance to corrosion. Finally, as a proof of concept, the CuNW-based composite TCEs were tested in dye-sensitized solar cells (DSSCs), showing similar performance to ITO based samples.
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Sahu, Gayatri. "Investigating the Electron Transport and Light Scattering Enhancement in Radial Core-Shell Metal-Metal Oxide Novel 3D Nanoarchitectures for Dye Sensitized Solar Cells." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1478.
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Dye-sensitized solar cells (DSSCs) have attained considerable attention during the last decade because of the potential of becoming a low cost alternative to silicon based solar cells. Electron transport is one of the prominent processes in the cell and it is further a complex process because the transport medium is a mesoporous film. The gaps in the pores are completely filled by an electrolyte with high ionic strength, resulting in electron-ion interactions. Therefore, the electron transport in these so called state-of-the-art systems has a practical limit because of the low electron diffusion coefficient (Dn) in this mesoporous film photoanode. This work focuses on the influence of the advanced core-shell nanoarchitecture geometry on electron transport and also on the influence of electron-ion interactions. In order to achieve the proposed goals, DSSCs based on ordered, highly aligned, 3D radial core-shell Au-TiO2 hybrid nanowire arrays were fabricated, using three different approaches. J-V, IPCE, and EIS characteristics were studied. The efficiency, light scattering and charge transport properties of the core-shell nanowire based devices were compared to TiO2 nanotube as well as TiO2 mesoporous film based DSSCs. The Au nanowires inside the crystalline TiO2 anatase nanoshell provided a direct conduction path from the TiO2 shell to the TCO substrate and improved transport of electrons between the TiO2 and the TCO. The optical effects were studied by IPCE measurement which demonstrated that Au-TiO2 nanowires showed an improved light harvesting efficiency, including at longer wavelengths where the sensitizer has weak absorption. The metal nanostructures could enhance the absorption in DSSCs by either scattering light enabling a longer optical path-length, localized surface plasmon resonance (LSPR) or by near-field coupling between the surface plasmon polariton (SPP) and the dye excited state. Rapid, radial electron collection is of practical significance because it should allow alternate redox shuttles that show relatively fast electron-interception dynamics to be utilized without significant sacrifice of photocurrent. A combination of improved electron transport and enhanced light harvesting capability make Au-TiO2 core-shell nanowire arrays a promising photoanode nanoarchitecture for improving photovoltaic efficiency while minimizing costs by allowing thinner devices that use less material in their construction.
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Madani, Sepideh Sadat. "Investigation of charge transport metal oxides for efficient and stable perovskite solar cells." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235892/1/Sepideh%2BSadat%2BMadani%2BThesis%282%29.pdf.
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This research investigates various thin-film metal oxides as charge transport layer for improving the performance and stability of perovskite solar cells. Physical Vapor Deposition techniques such as magnetron sputtering, and electron beam evaporation were used to fabricate the metal oxide thin films. The structural, morphological, chemical, optical, electrical, and electronic properties of the films were studied. Solar Cell Capacitance Simulator was employed for investigating the performance of the PSC using the experimental data as input parameters. Results showed that optimized properties of the metal oxide thin films as charge (hole) transport layer have improved the performance of the PSC device.
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Wang, Zixin. "TOWARDS HIGH-PERFORMANCE PEROVSKITE SOLAR CELLS BY CATHODE INTERFACIAL ENGINEERING WITH TERNARY METAL OXIDE AND DEVICE ENGINEERING WITH BULK HETROJUNCTION." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron149520580193777.
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Ren, He. "Towards High Performance Pedot: PSS-Free Polymer Solar Cells with Solution-Processed Metal Oxide Thin film as Hole Extraction Layer." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1406378486.
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Ali, Fawad. "Investigation of metal oxides thin films developed by PVD system for perovskite solar cells." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/127139/1/Fawad_Ali_Thesis.pdf.
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This research presents thin film deposition and characterization of metal oxides using industrially viable Physical Vapour Deposition (PVD) techniques. The research examines low temperature processed electron and hole transport metal oxides for high performance and stable perovskite solar cells. The physical, chemical, optical and electronic properties of the films were investigated and their device performance has been evaluated. The performance of the device improved and the materials cost reduced by replacing the expansive organic materials with more stable inorganic metal oxides.
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Das, Saikat. "FUNDAMENTAL STUDIES OF SURFACTANT TEMPLATED METAL OXIDE MATERIALS SYNTHESIS AND TRANSFORMATION FOR ADSORPTION AND ENERGY APPLICATIONS." UKnowledge, 2015. http://uknowledge.uky.edu/cme_etds/48.
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This work addresses fundamental aspects of designing templates and curing conditions for the synthesis of mesoporous metal oxide thin films. The first section addresses selection of cationic-carbohydrate surfactant mixtures to synthesize templated silica thin films for selective adsorption of simple carbohydrates based on molecular imprinting. Nuclear magnetic resonance and fluorescence spectroscopy results suggest a novel structure for mixtures of alkyl glucopyranosides or xylopyranosides with cationic (trimethylammonium) surfactants. Despite thermodynamically favorable mixing, the carbohydrate headgroups in the mixed micelle adopt an inverted configuration with their headgroups in the micelle core, and therefore are inaccessible for molecular imprinting. This orientation occurs even when the alkyl tail length of the carbohydrate surfactant is greater than that of the cationic surfactant, but this limitation can be overcome by introducing a triazole linker to the carbohydrate surfactant. The next section addresses the effects of aging conditions on the structural and chemical evolution of surfactant templated silica thin films. The third section describes the synthesis of carbohydrate/cationic surfactant imprinted silica thin films with orthogonally oriented cylindrical pores by modifying the glass surface with a random copolymer. The last part of the dissertation addresses the effect of pore orientation on the transformation mechanism of block copolymer templated titania thin films during high temperature curing. Mesoporous titania thin films can be used for photochemical and solar cell applications, but doing so requires addressing the tradeoff between loss of mesostructural order and growth of crystallinity during thermal treatment. By using advanced x-ray scattering techniques it has been shown that the titania films with vertically oriented pores can better withstand the anisotropic stress that develops during thermal treatment compare to titania films with mixed pore orientation. For instance, films with parallel or mixed pores can only be heated at 400 °C for a brief time (~10 min) without loss of order, while orthogonally oriented films can be heated at 550 °C or greater for extended time periods (on the order of hours) without significant loss of long-range mesopore structure. Detailed kinetic modeling was applied to enable the comparison of activation energy for mesostructure loss in films as a function of pore orientation and thickness.
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Natu, Gayatri. "Design and Synthesis of Metal Oxide Nanomaterials and Study of Their Electronic Properties for Energy Conversion via Dye-sensitized Solar Cells." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343823995.
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Park, Eunsol. "Synthesis of Tethering Group on Borylazadipyrromethene Dyes to Apply to Photogalvanic Dye-sensitized Solar Cells." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700072/.
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This is my thesis research on the preparation of borylazadipyrromethene (azaBODIPY) dyes bearing an anchoring group, such as a carboxylic acid group, at the β-pyrrolic position of the azadipyrromethene scaffold. Carboxylate groups form covalent bonds to oxide semiconductors such as TiO2 (n-type) or Cu2O (p-type) in dye-sensitized solar cells (DSCs) or photogalvanic dye-sensitized solar cells (P-DSCs). Oxide-binding azaBODIPY dyes can be used to investigate the rate and mechanism of electron injection from the dyes to the semiconductors. Two different types of azaBODIPY (difluoroboryl and dialkynylboryl) were prepared by following previously developed methods. To convert difluoroborylazaBODIPY to the final dyes having a carboxylic acid in the β-pyrrolic position, several distinct synthetic routes were designed, adopting various reactions, such as halogenation, Sonogashira coupling, Knoevenagel condensation, Grignard reagents, Vilsmeir-Haack, and Steglich esterification. Some of these reactions were successful, but the overall synthesis to the targeted final molecule couldn’t be accomplished. Even though further studies on the synthesis of oxide-binding azaBODIPYs are needed, at least my thesis research suggests what reactions can be implemented to complete this synthesis in the future. Proton NMR (nuclear magnetic resonance) and carbon NMR were commonly used to confirm the synthesized compounds, and sometimes crystallographic information was obtained by XRD (X-ray diffraction) whenever crystals of sufficient size and quality were grown. NMR spectra, interpreted by SpinWorks 3 software, and crystal structures will be introduced in each chapter.
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Augustine, B. (Bobins). "Efficiency and stability studies for organic bulk heterojunction solar cells." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526214436.
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Abstract The qualitative and quantitative characteristics of each component layer constituting the structure of organic bulk heterojunction solar cells (OSC-BHJ) contribute significantly towards its overall performance. One of the prevalent issues resulting in reduced device efficiency is due to the conformational inhomogeneities in the active and buffer layers. The mechanical stress, extended thermal exposure and presence of mutually reactive component layers etc., affects negatively on the device stability. Effective methods to address these issues will be extensively benefited by the industry since the current commercialisation of the technology is hindered owing to the lower efficiency and stability of these devices. This dissertation focuses on methods to coherently enhance the performance and longevity of the OSC-BHJ devices. The efficiency enhancements of the devices in this work were achieved through two main routes. The first route was through morphological improvement of the active layer. The second route was through boosting the electrical characteristics of hole transporting conducting polymer layer (HTL) by controlled annealing conditions. The introduction of a suitable additive in the active layer was found to reduce unfavourable phase segregation thus resulting in enhanced morphology. Further, the annealing conditions in different atmospheres (air, nitrogen and vacuum) were found to have a clear influence on the optimum functioning of the HTL in the device. Regarding the stability improvement study done in this work, a method of employing suitable interlayer was developed to effectively abate the internal degradation occurring in the device due to etching reaction on the indium tin oxide (ITO) anode by the HTL. Moreover, experimental investigations were carried out for drawing fundamental understanding of stability degenerating issues such as the influence of mechanical defects on transparent conducting metal oxide (ITO) anode on the performance of the device and heat induced degradations in the low band gap polymer-fullerene active layer. The highlight of this research is that the discovered methods are inexpensive, efficient, and easy to adopt. The results of the study could help the technology to overcome some of its limitations and accelerate its progress towards commercialisationTiivistelmä Orgaanisten heteroliitosaurinkokennojen kerrosrakenteen ominaisuudet ja laatu vaikuttavat merkittävästi aurinkokennojen toiminnallisuuteen. Erityisesti rakenteelliset epähomogeenisuudet aktiivi- ja puskurikerroksissa heikentävät kennon hyötysuhdetta. Kennojen stabiilisuutta tarkasteltaessa myös mekaanisella rasituksella, pitkittyneellä lämpöaltistuksella ja materiaalien reagoinneilla keskenään kerrosten välillä, on selkeä negatiivinen vaikutus kennojen stabiilisuuteen. Orgaanisen aurinkokennoteknologian kaupallistamisen rajoitteina ovat kennojen heikko hyötysuhde ja stabiilisuus, joten menetelmät jotka tarjoavat ratkaisuja edellä mainittuihin ongelmiin, ovat erittäin tärkeitä teknologiaa kaupallistavalle teollisuudelle. Tämä väitöskirja keskittyy johdonmukaisesti selvittämään tapoja, joilla voidaan parantaa heteroliitosaurinkokennojen hyötysuhdetta ja elinikää. Hyötysuhteen tehostamiseksi valittiin kaksi eri lähestymistapaa, joista ensimmäisessä keskityttiin aktiivikerroksen morfologian parantamiseen ja toisessa aukkoja kuljettavan kerroksen sähköisten ominaisuuksien parantamiseen lämpökäsittelyprosessin avulla. Sopivan lisäaineen avulla aktiivikerroksen ei-toivottua kiteytymistä voidaan pienentää ja parantaa näin kerroksen morfologiaa. Lisäksi työssä todettiin, että lämpökäsittelyn aikaisella ympäristöolosuhteella (ilma, typpi, tyhjiö) on merkittävä vaikutus puskurikerroksen optimaaliseen toimintaan aurinkokennossa. Stabiilisuuden parantamiseksi kehitettiin välikerroksen hyödyntämiseen perustuva menetelmä, jolla voidaan tehokkaasti vähentää kennojen sisäisessä rakenteessa tapahtuvaa toiminnallisuuden heikkenemistä, joka aiheutuu aukkoja kuljettavan kerroksen syövyttävästä vaikutuksesta indiumtinaoksidi (ITO) pohjaiseen anodiin. Tämän lisäksi työssä tutkittiin kokeellisesti stabiilisuuteen heikentävästi vaikuttavia tekijöitä, kuten mekaanisen rasituksen aiheuttamia vaurioita metallioksidi (ITO) anodissa ja lämpöaltistuksesta aiheutuvia vikoja polymeeri-fullereeni rakenteeseen perustuvassa aktiivikerroksessa. Tutkimuksen keskeisin tulos on, että esitellyt keinot aurinkokennojen hyötysuhteen ja stabiilisuuden parantamiseen ovat edullisia, tehokkaita ja helppoja hyödyntää. Tulokset voivat merkittävästi edistää orgaanisten aurinkokennojen teknistä kehitystä ja kiihdyttää niiden tuloa kaupallisiksi tuotteiksi
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Chistiakova, Ganna [Verfasser], Bernd [Akademischer Betreuer] Rech, Klaus [Gutachter] Lips, Uwe [Gutachter] Rau, and Bernd [Gutachter] Rech. "Development of metal oxide thin films as carrier selective contacts for silicon heterojunction solar cells / Ganna Chistiakova ; Gutachter: Klaus Lips, Uwe Rau, Bernd Rech ; Betreuer: Bernd Rech." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1210998440/34.
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Fan, Liangdong. "Development and characterization of functional composite materials for advanced energy conversion technologies." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134111.
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The solid oxide fuel cell (SOFC) is a potential high efficient electrochemical device for vehicles, auxiliary power units and large-scale stationary power plants combined heat and power application. The main challenges of this technology for market acceptance are associated with cost and lifetime due to the high temperature (700-1000 oC) operation and complex cell structure, i.e. the conventional membrane electrode assemblies. Therefore, it has become a top R&D goal to develop SOFCs for lower temperatures, preferably below 600 oC. To address those above problems, within the framework of this thesis, two kinds of innovative approaches are adopted. One is developing functional composite materials with desirable electrical properties at the reduced temperature, which results of the research on ceria-based composite based low temperature ceramic fuel cell (LTCFC). The other one is discovering novel energy conversion technology - Single-component/ electrolyte-free fuel cell (EFFC), in which the electrolyte layer of conventional SOFC is physically removed while this device still exhibits the fuel cell function. Thus, the focus of this thesis is then put on the characterization of materials physical and electrochemical properties for those advanced energy conversion applications. The major scientific content and contribution to this challenging field are divided into four aspects except the Introduction, Experiments and Conclusions parts. They are: Continuous developments and optimizations of advanced electrolyte materials, ceria-carbonate composite, for LTCFC. An electrolysis study has been carried out on ceria-carbonate composite based LTCFC with cheap Ni-based electrodes. Both oxygen ion and proton conductance in electrolysis mode are observed. High current outputs have been achieved at the given electrolysis voltage below 600 oC. This study also provides alternative manner for high efficient hydrogen production. Compatible and high active electrode development for ceria-carbonate composite electrolyte based LTCFC. A symmetrical fuel cell configuration is intentionally employed. The electro-catalytic activities of novel symmetrical transition metal oxide composite electrode toward hydrogen oxidation reaction and oxygen reduction reaction have been experimentally investigated. In addition, the origin of high activity of transition metal oxide composite electrode is studied, which is believed to relate to the hydration effect of the composite oxide. A novel all-nanocomposite fuel cell (ANFC) concept proposal and feasibility demonstration. The ANFC is successfully constructed by Ni/Fe-SDC anode, SDC-carbonate electrolyte and lithiated NiO/ZnO cathode at an extremely low in-situ sintering temperature, 600 oC. The ANFC manifests excellent fuel cell performance (over 550 mWcm-2 at 600 oC) and a good short-term operation as well as thermo-cycling stability. All results demonstrated its feasibility and potential for energy conversion. Fundamental study results on breakthrough research Single-Component/Electrolyte-Free Fuel Cell (EFFC) based on above nanocomposite materials (ion and semi-conductive composite) research activities. This is also the key innovation point of this thesis. Compared with classic three-layer fuel cells, EFFC with an electrolyte layer shows a much simpler but more efficient way for energy conversion. The physical-electrical properties of composite, the effects of cell configuration and parameters on cell performance, materials composition and cell fabrication process optimization, micro electrochemical reaction process and possible working principle were systematically investigated and discussed. Besides, the EFFC, joining solar cell and fuel cell working principle, is suggested to provide a research platform for integrating multi-energy-related device and technology application, such as fuel cell, electrolysis, solar cell and micro-reactor etc. This thesis provides a new methodology for materials and system innovation for the fuel cell community, which is expected to accelerate the wide implementation of this high efficient and green fuel cell technology and open new horizons for other related research fields.QC 20131122
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Cojocaru, Ludmila. "Films d’oxydes semi-conducteurs nanoporeux et nanocristallins pour dispositifs photovoltaïques hybrides." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14630/document.
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Dans le contexte de la mise au point de dispositifs photovoltaïques efficaces, bon marché et respectueux de l’environnement, la synthèse d’oxydes métalliques semi-conducteurs tels que SnO2, Zn2SnO4 et WO3 de morphologies et textures diverses a été développée afin d’élaborer des photoanodes poreuses pour cellules solaires à colorant. D’après les études réalisées par différentes méthodes (MEB, MET, DRX et BET), les matériaux obtenus présentent des caractéristiques texturales, morphologiques et structurales appropriées pour l’application visée. Des cellules solaires à colorant ont donc été réalisées à partir de ces oxydes, puis différents paramètres influençant leurs performances ont été optimisés afin d’améliorer l’efficacité de la conversion photovoltaïque. Notamment l’influence positive de différents traitements des photoanodes (i.e. solution aqueuse de TiCl4 ou traitement à l’eau) sur les rendements de conversion énergétique et la stabilité des dispositifs a été démontrée. Ainsi, des performances comparables ou supérieures à l’état de l’art ont été atteintes pour les systèmes à base de SnO2. Ces performances ont ensuite été interprétées en déterminant les processus électroniques et ioniques ayant lieu dans ces cellules par différentes méthodes physiques (mesures de tension de seuil et de décroissance de circuit-ouvert, spectroscopie d’impédance). Enfin, des électrodes réalisées à partir de WO3 déposé sur substrats flexibles ont démontré des propriétés électrochromes très prometteuses ce qui ouvre de nouvelles perspectives dans le domaine de l’affichageIn the context of the development of efficient, low-cost and environmentally friendly photovoltaic devices, the synthesis of metal-oxide semiconductors such as SnO2, Zn2SnO4 and WO3 with various textures and morphologies have been developed in order to achieve nanoporous photoanodes for dye-sensitized solar cells. According to studies carried out by different characterization methods (SEM, TEM, XRD and BET), the resulting materials show interesting features for the expected application. Dye solar cells were then fabricated from photoanodes processed with these oxides and several parameters influencing their performance were optimized to improve the overall conversion efficiency. In particular, the beneficial effect of different treatments of the photoanodes (ie aqueous TiCl4 or water treatment) on the power conversion efficiency and the stability of the devices has been evidenced. Thus, state-of-the art or, even, record efficiencies were reached in the case of SnO2-based systems. These performances were then rationalized by determining the electronic and ionic processes occurring in these devices by various physical methods (threshold voltage and open-circuit photovoltage decay measurements, electrochemical impedance spectroscopy). Finally, electrodes based on WO3 and deposited on flexible substrates have shown very promising electrochromic properties, which opens up new prospects in the field of smart displays
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Silva, Audrey Roberto 1964. "Texturização da superfície de silício monocristalino com NH4OH e camada antirrefletora para aplicações em células fotovoltaicas compatíveis com tecnologia CMOS = Texturing the surface of monocrystalline silicon with NH4OH and anti-reflective coating for applications in photovoltaic cells compatible with CMOS technology." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259291.
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Orientador: José Alexandre DinizDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Este trabalho apresenta o desenvolvimento de células fotovoltaicas de junção n+/p em substratos de Si com processos de fabricação totalmente compatíveis com a tecnologia CMOS (Complementary Metal Oxide Semiconductor). Os processos compatíveis desenvolvidos neste trabalho sao as técnicas: i) de texturização da superfície do Si, com reflexao da superficie texturizada de 15% obtida com a formação de micro-pirâmides (alturas entre 3 e 7 ?m), utilizando-se solução alcalina de NH4OH (hidróxido de amônia), que e livre da contaminação indesejável por íons de Na+ e K+ quando se utiliza soluções tradicionais de NaOH e de KOH, respectivamente, e ii) de deposição ECR-CVD (Electron Cyclotron Resonance - Chemical Vapor Deposition) da camada antirrefletora (ARC) de SiNX (nitreto de silício), que e executada em temperatura ambiente, portanto pode ser feita apos a finalização da célula sem danificar trilhas metálicas e alterar a profundidade da junção n+/p. A caracterização desta camada ARC mostrou que o nitreto tem índice de refração de 1,92 e refletância mínima de 1,03%, o que e um excelente resultado para uso em células solares (ou fotovoltaicas). Foram fabricadas cinco series de células fotovoltaicas, utilizando-se a texturização com NH4OH e a camada antirrefletora de nitreto de Si. Em quatro series utilizou-se o processo de implantação de íons de fósforo (31P+), com posterior recozimento, para a formação da região n+, enquanto que na quinta serie foi utilizado o processo de difusão térmica. As eficiências máximas para as células fabricadas são de 9% e de 12%, respectivamente, para as células feitas utilizando os processos de implantação e de difusão térmica, indicando que a implantação de íons causa danos na rede cristalina do silício, que o posterior recozimento não consegue corrigir, o que reduz a eficiência da célula
Abstract: This work presents the development of photovoltaic cells based on n+/p junction in Si substrates, with fully compatible fabrication processes with CMOS technology. The compatible processes, which are developed in this study, are the techniques: i) of Si surface texturing, with the textured surface reflection of 15% obtained by the formation of micro-pyramids (heights between 3 and 7 ?m) using NH4OH (ammonium hydroxide) alkaline solution, which is free of undesirable contamination by Na + and K + ions, when NaOH and KOH traditional solutions are used, respectively, and ii) of the ECR-CVD (Electron Cyclotron Resonance - Chemical Vapor Deposition) deposition of SiNx (silicon nitride) anti-reflective coating (ARC), which is carried out at room temperature and can be performed after the end of cell fabrication without damage on metallic tracks and without variation of n+/p junction depth. The ARC coating characterization presented that the silicon nitride has a refractive index of 1.92 and a minimum reflectance of 1.03%, which is an excellent result for application in solar (or photovoltaic) cells. Five series of photovoltaic cells were fabricated, using the NH4OH solution texturing and the silicon nitride antireflective coating. In the first four series, phosphorus (31P+) ion implantation process, with subsequent annealing to get the region n+, was used, while, in the fifth series was used the thermal diffusion process. The maximum efficiency values are of 9% and 12%, respectively, for cells, which were fabricated using the ion implantation and thermal diffusion processes, indicating that the ion implantation damages the silicon crystal lattice and the subsequent annealing cannot rectify, which reduces the cell efficiency
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Ghamgosar, Pedram. "Advanced Metal Oxide Semiconductors for Solar Energy Harvesting and Solar Fuel Production." Licentiate thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64922.
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Increasing energy consumption and its environmental impacts make it necessary to look for alternative energy sources. Solar energy as huge energy source which is able to cover the terms sustainability is considered as a favorable alternative. Solar cells and solar fuels are two kinds of technologies, which make us able to harness solar energy and convert it to electricity and/or store it chemically. Metal oxide semiconductors (MOSs) have a major role in these devices and optimization of their properties (composition, morphology, dimensions, crystal structure) makes it possible to increase the performance of the devices. The light absorption, charge carriers mobility, the time scale between charge injection, regeneration and recombination processes are some of the properties critical to exploitation of MOSs in solar cells and solar fuel technology. In this thesis, we explore two different systems. The first one is a NiO mesoporous semiconductor photocathode sensitized with a biomimetic Fe-Fe catalyst and a coumarin C343 dye, which was tested in a solar fuel device to produce hydrogen. This system is the first solar fuel device based on a biomimetic Fe-Fe catalyst and it shows a Faradic efficiency of 50% in hydrogen production. Cobalt catalysts have higher Faradic efficiency but their performance due to hydrolysis in low pH condition is limited. The second one is a photoanode based on the nanostructured hematite/magnetite film, which was tested in a photoelectrochemical cell. This hybrid electrode improved the photoactivity of the photoelectrochemical cell for water splitting. The main mechanism for the improvement of the functional properties relies with the role of the magnetite phase, which improves the charge carrier mobility of the composite system, compared to pure hematite, which acts as good light absorber semiconductor. By optimizing the charge separation and mobility of charge carriers of MOSs, they can be a promising active material in solar cells and solar fuel devices due to their abundance, stability, non-toxicity, and low-cost. The future work will be focused on the use of nanostructured MOSs in all-oxide solar cell devices. We have already obtained some preliminary results on 1-dimensional heterojunctions, which we report in Chapter 3.3. While they are not conclusive, they give an idea about the future direction of the present research.
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Besharat, Zahra. "Adsorption of molecular thin films on metal and metal oxide surfaces." Doctoral thesis, KTH, Materialfysik, MF, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195613.
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Metal and metal oxides are widely used in industry, and to optimize their performance their surfaces are commonly functionalized by the formation of thin films. Self-assembled monolayers (SAMs) are deposited on metals or metal oxides either from solution or by gas deposition. Thiols with polar terminal groups are utilized for creating the responsive surfaces which can interact electrostatically with other adsorbates. Surface charge effects wetting and adhesion, and many other surface properties. Polar terminal groups in thiols could be used to modify these factors. Mixed SAMs can provide more flexible surfaces, and could change the resulting surface properties under the influence of factors such as pH, temperature, and photo-illumination. Therefore, in order to control these phenomena by mixed polar-terminated thiols, it is necessary to understand the composition and conformation of the mixed SAMs and their response to these factors. In this work, mixtures of thiols with carboxylic and amino terminal groups were studied. Carboxylic and amino terminal groups of thiol interact with each other via hydrogen bonding in solution and form a complex. Complexes adsorb to the surface in non-conventional orientations. Unmixed SAMs from each type, either carboxylic terminated thiols or amino terminated thiols are in standing up orientation while SAMs from complexes are in an axially in-plane orientation. Selenol is an alternative to replace thiols for particular applications such as contact with biological matter which has a better compatibility with selenol than sulfur. However, the Se-C bond is weaker than the S-C bond which limits the application of selenol. Understanding the selenol adsorption mechanism on gold surfaces could shed some light on Se-C cleavage and so is investigated in this work. Se-C cleavage happens in the low coverage areas on the step since atoms at steps have lower coordination making them more reactive than atoms on the terraces. Another area where the self-assembly of molecules is of importance is for dye sensitized solar cells, which are based on the adsorption of the dye onto metal oxides surfaces such as TiO2.The interface between the SAM of dye and the substrate is an important factor to consider when designing dyes and surfaces in dye sensitized solar cells (DSSCs). The quality of the self-assembled monolayers of the dye on the TiO2 surface has a critical influence on the efficiency of the DSSCs. Creation of just a monolayer of dye on the surface could lead to an efficient current of photo-excited electrons to the TiO2 and degeneration of the dye by redox. This work, T-PAC dye showed island growth with some ad-layer that is not in contact with the surface, whereas the MP13 dye adsorption is laminar growth. Cuprite (Cu2O) is the initial and most common corrosion product for copper under atmospheric conditions. Copper could be a good replacement for noble metal as catalysts for methanol dehydrogenation. Knowledge about the structure of Cu2O(100) and Cu2O(111) surfaces could be used to obtain a deeper understanding of methanol dehydrogenation mechanisms with respect to adsorption sites on the surfaces. In this work, a detailed study was done of Cu2O(100) surface which revealed the possible surface structures as the result of different preparation conditions. Studies of the structure of Cu2O(100) and Cu2O(111) surfaces show that Cu2O(100) has a comparatively stable surface and reduces surface reactivity. As a consequence, dehydrogenation of methanol is more efficient on the Cu2O(111) surface. The hydrogen produced from methanol dehydrogenation is stored in oxygen adatom sites on both surfaces.QC 20161107
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LAMBERTI, ANDREA. "Metal-oxide nanostructures for energy applications." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506221.
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One of the most important challenges for our society is providing powerful devices for energy conversion and storage. The number of proposed technologies in today’s green and renewable energy science is large and still increasing: among all the dye-sensitized solar cells (for energy generation) and Li-ions batteries (for energy storage) have attracted a lot of interest thanks to the easy fabrication processes and the cheap materials involved.
Great attention has been paid on the investigation of one-dimensional metal-oxide nanostructures for a new generation of power sources, because of their unique electronic properties, such as high electron mobility and low carrier recombination rate, high surface-to-volume ratio and excellent surface activity.
Among the large number of semiconductive metal oxide nanostructures, TiO2 and ZnO are of particular interest due to the fact that they are the best candidates as active materials in electrochemical devices thanks to their chemical and electronic properties.
Several approaches have been proposed for TiO2 nanostructure synthesis and among them anodic oxidation is now a well-established technique that can provide large area uniform nanotubular arrays on Ti foil with relatively high specific surface.
Regarding zinc oxide, many papers report on the synthesis of ZnO nanostructures performed by means of different techniques. Most of them exploits high temperature processes often using catalyst particles, requires the presence of a sacrificial template, introduces chemical contamination or exhibit slow kinetics.
This PhD thesis investigates the fabrication of different metal-oxide nanostructures and their integration as electrodes into DSCs and LiBs: in particular the work deals with TiO2 nanotube arrays obtained by anodic oxidation and with ZnO sponge-like films obtained by combined sputtering/thermal oxidation techniques.
Vertically oriented TiO2 NTs were obtained by anodic oxidation of titanium foil and fully characterized in terms of stoichiometry, crystalline phase and morphology. TiO2 nanotubes were tested both in DSC and in LiBs showing improved charge transport properties due to the 1-dimensional structures and a reduced recombination rate (and a subsequent higher carrier lifetime value) that could be attributed to the reduced presence of defects and trap-sites in the nanotubes with respect to the nanoparticle-based electrodes.
As competitive alternative to TiO2 nanotubes, porous ZnO films were obtained by a simple two-step method, involving the sputtering deposition of a sponge-like layer of metallic zinc, followed by a low-temperature treatment allowing for the complete oxidation of zinc, thus forming sponge-like ZnO films. Also in this case ZnO nanostructured films were fully characterized tested both in DSC and in LiBs showing interesting performance. Thanks to the its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, ZnO sponge-like can combine the fast transport properties of one dimensional material and the needed surface area usually provided by nanocrystalline electrodes.
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Wang, Chenggong. "Interface Studies of Organic/Transition Metal Oxide with Organic Semiconductors and the Interfaces in the Perovskite Solar Cell." Thesis, University of Rochester, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3723336.
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In recent decades, research and development of organic based semiconductor devices have attracted intensive interests. One of the most essential elements is to understand the electronic structures at various interfaces involved in these devices since the interface properties control many of the critical electronic processes. It is thus necessary to study the electronic properties of the organic semiconductors with surface analytical tools to improve the understanding of the fundamental mechanisms involved in the interface formation. This thesis covers the experimental investigations on some of the most interesting topics raised in the recent development of organic electronic devices. The thesis intends to reveal the physical processes at the interface and their contribution to the device performance with photoemission and inverse photoemission investigations on the evolution of the occupied and unoccupied electronic structures. I will report a substantial difference in the electron affinity of CuPc on two substrates as the orientations of CuPc are different. I will also illustrate that the CuPc has standing up configuration on one monolayer of C60 on SiO2 while lying down on one monolayer of C60 on HOPG. Meanwhile, the CuPc on more than one monolayers of C60 on different substrates show that the substrate orientation effect vanished. Then I will propose a two-stage model to describe the bulk doping effect of C60 by molybdenum oxide. I will also demonstrate that the doping effect of C60 by ultra-thin layer molybdenum oxide is weaker than that by interface doping and bulk doping. I will demonstrate that for Au on CH3NH3PbI3, hole accumulation occurs at the vicinity of the interface, facilitating hole transfer from CH3NH3PbI3 to Au. I will show a strong initial shift of core levels to lower binding energy in C60 on CH3NH3PbI3 interface, which indicates that electrons transfer from the perovskite film to C60 molecules. I will further demonstrate that the molybdenum oxide surface can be passivated by approximately two monolayers of organic thin films against exposure to air. I will discuss the mechanism that how oxygen plasma treatment effectively recover the high work function drop of molybdenum oxide by air exposure. At the end, I will show that a small energy offset at Pentacen/C60 heterojunction makes it easy to transfer electrons from Pentacene to C60 even under a small applied bias, facilitating the occurrence of charge generation. Finally, I will summarize the thesis.
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Makineni, Anil Kumar. "Construction and realisation of measurement system in a radiation field of 10 standard suns." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-17209.
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A measurement system is to be presented, which is used to obtain the I-V characteristics of a solar cell and to track its temperature during irra-diation before mounting it into a complete array/module. This project presents both the design and implementation of an Electronic load for testing the solar cell under field conditions of 10000 W/m^2, which is able to provide current versus voltage and power versus voltage charac-teristics of a solar cell using a software based model developed in Lab-VIEW. An efficient water cooling method which includes a heat pipe array system is also suggested. This thesis presents the maximum power tracking of a solar cell and the corresponding voltage and current values. In addition, the design of the clamp system provides an easy means of replacing the solar cell during testing.Keywords: Solar cell, Metal Oxide Semiconductor Field Effect Transistor (MOSFET), I-V characteristics, cooling system, solar cell clamp system, LabVIEW, Graphical User Interface (GUI).
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Strandberg, Leo, and Zivojin Mirovic. "Hållbar kraftförsörjning av signalanläggningar : En undersökning av Roslagsbanans signalsäkerhetsutrustning." Thesis, KTH, Hälsoinformatik och logistik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-230635.
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Roslagsbanans signalanläggningar har flera olika lösningar för dess strömförsörjning i form av standarder för batterier och likriktare. Denna lösningsvariation har försvårat för underhållspersonalen att åtgärda de fel som uppstått och därmed fördröjt trafiken, dvs trafikstörningar. Roslagsbanan försörjs delvis av lokala elnät där avbrott emellanåt förekommer. Dessa avbrott inträffar ofta när elnätsleverantörerna underhåller sitt ortnät vilket kan ske även under rusningstrafik. Avbrotten kan även orsakas inom signalanläggningarna när stora spänningsvariationer förekommer, t.ex. när stora induktiva- eller kapacitiva laster slås av. Dessa problem analyseras och åtgärdsförslag tas fram i denna rapport. De befintliga likriktarna och batterierna samt förslag till ersättningsprodukter som behövs för detta säkerhetssystem har sammanställts i denna rapport. För att skapa en hållbar, robust och miljövänlig strömförsörjning till Roslagsbanans signalanläggningar undersöktes i detta arbete strömspikar, avbrottsfri kraftförsörjning samt dessutom möjligheten att ansluta solceller som kompletterande åtgärd. I signalutrustningen vid Roslags Näsby stationsområde detekterades och undersöktes förekomsten av strömspikar. Två åtgärdsförslag för att komma till rätta med dessa strömspikar togs fram. Förslagen var ett lågpassfilter och en metalloxidvaristor som båda var för sig reducerar strömspikarna. Lågpassfiltret dämpar insignalernas spänning och strömförsörjning vid kraftiga förändringar i frekvensen och metalloxidvaristorn reducerar strömflödet vid överspänningar. Ytterligare undersökningar av transienterna i Roslags Näsbys och de övriga signalanläggningarna på Roslagsbanan bör utföras. Resultaten av de genomförda undersökningarna om avbrottsfri kraftförsörjning och solceller visade däremot att utrustningarna inte bör installeras i de nuvarande signalanläggningarna. Solceller var inte implementerbara eftersom effektbehovet av signalanläggningarna var större än den takyta som fanns tillgänglig för solcellerna. Arbete och investeringar för ett avbrottsfritt kraftförsörjningsunderhåll och installation av denna utrustning var mer krävande i jämförelse med dess nytta för signalanläggningarnas tillförlitlighet, dvs ingen åtgärd i nuläget. Förslag på ersättningsprodukter i form av likriktare och batterier lades fram till arbetsgivarna för att skapa en standard för Roslagbanans kraftförsörjning framåt.Roslagsbanan's signal systems have several different solutions for its power supply in the form of several standards for batteries and rectifiers. This solution variation has made it difficult for maintenance staff to correct the errors that occurred and thus delayed traffic, i.e. traffic disturbances. Roslagsbanan is partly supplied by local power grids where interruptions occur occasionally. These interruptions often occur when the network service providers maintain their home network, which may also occur during rush hour traffic. The interruptions can also be caused by the signal systems them self when large voltage variations occur, e.g. when large inductive or capacitive loads are switched off. These problems are analysed, and action proposals are presented in this report. The existing rectifiers and batteries as well as proposals for replacement products that are needed for this safety system have been compiled in this report. To create a sustainable, robust and environmentally friendly power supply to Roslagsbanan’s signal systems, this work investigated transients, uninterruptible power supply, as well as the possibility of connecting solar cells as a complementary arrangement. An investigation of the signal equipment at Roslags Näsby station area showed presence of transients. Two proposals to reduce these transients were presented. The proposals were a low pass filter and a metal oxide varistor, both individually reduces transients. The low pass filter attenuates the voltage and current of the signal when the strong frequency changes occurs and the metal oxide varistor reduces the current flow at overvoltages. Further investigations of the transients in Roslags Näsbys and the other signal facilities on the Roslagsbanan should be performed. On the other hand, the results of the investigations on uninterruptible power and solar cells showed that the equipment should not be installed in the current signal systems. Solar cells were not implementable because the power requirement of the signal systems was greater than the current ceiling area for the solar cells. The work and investment for uninterruptible power supply maintenance and installation were more demanding in comparison to its usefulness for the reliability of the signal systems. Proposals for replacement products were submitted to employers to create a standard for Roslagbanan's power supply onwards.
Сигнални систем на железници која се зове Рослагсбана садржи више различитих решења за своје напајање у облику неколико стандарда за батерије и исправљаче. Варијација различитих решења проузроковала je потешкоће у отклањању новонасталих грешака служби које се баве одржавањем и изазвала је застој у железничком саобраћају. Рослагсбана се напаја електричном енергијом из локалних мрежа на којима може доћи до прекида. Прекид напајања електричном енергијом може бити изазван наглим променама напона у сигналним системима и уколико локални дистрибутер изводи радове на одржавању електричне мреже. Проблеми који могу настати променама напона се анализирају и испитују у овом извештају. Попис исправљача и батерија као и њихова стандардна решења су обрађени и представљени у циљу стварања одрживог и дугорочног решења за системску сигнализацију. Анализирани су високонапонски шпицеви, системи за непрекидно напајање електричном енергијом (УПС) и могућност прикључивања соларних панела. У сигналном систему на станици Рослас Насби измерени су високонапонски шпицеви. Како би се дошло до најбољег и најповољнијег решења анализирана су два предлога за њихово уклањање. Један предлог за уклањање био је ниско пропусни филтер док је за редукцију предложен метал- оксидни одводник пре напона (МОВ). Ниско пропусни филтер смањује јачину струје и напона уколико фреквенција пређе одређену претходно утврђену границу, док МОВ редукује ток струје уколико дође до скока напона. Пре имплементације било ког од наведених решења треба извршити накнадна испитивања у вези са напонским шпицевима. Резултати указују да имплементација УПС-а и соларних панела није могућа. Могућност соларних панела да произведу довољну количину енергије која је потребна за одређени систем није сразмерна површини система која би могла да се прекрије соларним панелима. Трошкови одржавања и прикључивања УПС система су већи у поређењу са значајем које би систем имао од самог УПС система. Предлог стандардних батерија и исправљача који је представљен послодавцу коригован је како би се дошло до стандардног решења за све предстојеће пројекте.
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Vedraine, Sylvain. "Intégration de nanostructures plasmoniques au sein de dispositifs photovoltaïques organiques : étude numérique et expérimentale." Phd thesis, Aix-Marseille Université, 2012. http://tel.archives-ouvertes.fr/tel-00799088.
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Les cellules solaires en couches minces permettent de produire de l'énergie à bas-coût et sans émission de gaz à effet de serre. Dans le but de réaliser des dispositifs toujours plus performants, nous étudions l'impact de l'intégration de nanostructures métalliques (NSs) au sein de cellules solaires organiques (CSO). Ces NSs peuvent alors générer des effets diffusifs et des résonances issues de plasmons de surface. A l'aide d'un modèle numérique FDTD, nous démontrons que l'ingénierie plasmonique peut servir à augmenter l'absorption dans le matériau photoactif tout en limitant l'énergie perdue sous forme de chaleur dans les NSs. L'influence de paramètres opto-géométriques de structures associant matériaux organiques et effets plasmoniques est étudiée (diamètre, position des particules dans la couche et période du réseau de particules sphériques). Expérimentalement, des NSs d'argent ont été réalisées par évaporation sous vide puis intégrées dans des couches organiques. Nous avons mesuré une exaltation de l'absorption optique dans la gamme spectrale utile à la photo-conversion. Trois architectures différentes de CSO plasmonique ont été fabriquées et caractérisées par MEB, TEM et ToF-SIMS, puis modélisées, permettant d'identifier des verrous technologiques et de proposer des pistes d'amélioration. Nous avons aussi intégré des NSs au sein d'un empilement transparent et conducteur de type oxyde/métal/oxyde, dans le but de remplacer l'électrode classique en oxyde d'indium et d'étain d'une CSO. Le rôle de chaque couche de l'empilement sur le comportement optique de l'électrode est discuté. Les épaisseurs des couches d'une électrode de type ZnO/Ag/ZnO ont été optimisées.
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Bou, Adrien. "Electrodes multifeuillets de type oxyde/métal/oxyde à transparence accordable pour cellules solaires organiques." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4367.
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Parmi les filières de cellules photovoltaïques, les cellules solaires organiques suscitent un intérêt industriel par leur faible coût financier et de production énergétique et leur application possible sur des substrats flexibles de type plastique. L'ITO (Indium Tin Oxide) est l'électrode transparente conductrice (ETC) la plus utilisée pour ces cellules ainsi que pour d'autres dispositifs optoélectroniques. Cependant, ce matériau n'est pas sans présenter certains inconvénients (rareté de l'indium, structure non adaptée à des substrats flexibles,…), et la recherche d'alternatives à l'ITO est une préoccupation actuelle de la communauté scientifique internationale. Une possibilité est alors offerte par des structures multicouches de type Oxyde|Métal|Oxyde. Le rôle des deux couches d’oxydes est d’accorder, en ajustant les épaisseurs, la position, l’intensité et la largeur de la fenêtre spectrale de transmission. Des travaux numériques et expérimentaux couplés ont été effectués en particulier sur les structures SnOx|Ag|SnOx, TiOx|Ag|TiOx et ZnS|Ag|ZnS. Par microstructuration de telles électrodes ou bien par incorporation d’un bicouche Cu|Ag comme feuillet métallique au coeur de la structure, il est possible d’améliorer leurs performances optiques en amplifiant et en élargissant la fenêtre spectrale de transmission, sans dégrader leur haute conductivité. L’intégration d’électrodes SnOx|Ag|SnOx et TiOx|Ag|TiOx au sein de cellules solaires organiques inverses a été entrepris. Des résultats photoélectriques très prometteurs ont été obtenus avec la structure TiOx|Ag|TiOx qui permet d’atteindre des performances de niveau quasi-équivalent aux cellules de référence à base d’ITOAmong all variants of photovoltaic thins films, organic solar cells generate a major industrial interest due to low manufacturing costs, reasonable levels of energy production and suitability to flexible substrates like plastic. ITO (Indium Tin Oxide) is the most used Transparent Conductive Electrode (TCE) for organic solar cells as well as other optoelectronic devices. However, this material is not without drawbacks (scarcity of indium, non-suitability to flexible substrates...), and the search for alternatives to ITO is actively pursued by the international scientific community. One possibility is offered by Oxide|Metal|Oxide multilayer structures. By reaching the thin metal layer percolation threshold and by varying its thickness, it is possible to obtain very high conductivity and transparency of this multilayer in the visible spectral range. The role of both oxide layers is to tune the position, intensity and width of the spectral transmission window by adjusting the oxides’ thicknesses. Coupled experimental and numerical works were lead in particularly on SnOx|Ag|SnOx, TiOx|Ag|TiOx and ZnS|Ag|ZnS structures. By microstructuring such electrodes, or by incorporating a Cu|Ag bilayer as metal sheet at the core of the structure, it is possible to increase the optical performances by amplifying and expanding the spectral transmission window without degrading the high conductivity. The integration of SnOx|Ag|SnOx and TiOx|Ag|TiOx electrodes in inversed organic solar cells was undertaken. Very promising photoelectric results were obtained with the TiOx|Ag|TiOx structure which allows to reach performances close to that obtained with ITO-based reference cells
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Katz, Jordan E. "Metal Oxide-Based Photoelectrochemical Cells for Solar Energy Conversion." Thesis, 2008. https://thesis.library.caltech.edu/4186/1/Jordan_Katz_Thesis2007.pdf.
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In order to address the need for CO2-free energy, recent trends in global CO2 emissions and energy production are analyzed, and the photoelectrochemical properties of two types of metal oxide-based solar cells are presented.
The effects of potential-determining cations (Li+, H+) in the electrolyte of TiO2-based dye-sensitized solar cells, using Ru(H2L’)2(NCS)2, where H2L’ is 4,4’-dicarboxylic acid-2,2’bipyridine, as a sensitizer was investigated using current density vs potential (J-E), spectrochronocoulometric, and spectroscopic methods. Photoelectrochemical cells with lower concentrations of the cations Li+ and H+ had increased open-circuit voltages (Voc), and decreased short-circuit current densities (Jsc). Spectrochronocoulometric methods indicated that the energy of states in TiO2 shifted by approximately -1 V when in contact with electrolytes lacking small cations. Spectral response measurements indicated that the loss of photocurrent was accompanied by a nearly monotonic drop in the external quantum yield across all wavelengths.
Transient absorption spectroscopy was used to measure the kinetics of interfacial electron transfer of the same system. No dependence was observed on the ultrafast dynamics of electron injection on cations used in ClO4--based solutions. However, in solutions of TBA+ with I3-/I-, femtosecond, but not picosecond, dynamics were observed. In contrast, for solutions with Li+ and ClO4-, I- or I-/I3-, both femtosecond and picosecond dynamics were observed. Nanosecond-resolved spectroscopy results show that the absence of small cations did not affect the rate of recombination, while the regeneration rate of [RuIII(H2L’)2(NCS)2]+ was decreased. Results indicate that both the ground and excited state reduction potentials of the sensitizer shift as a function of small cations in solution, along with the energy of states in TiO2. The efficiency of electron injection is thus largely unchanged; rather a decrease in the regeneration rate accounts for the loss of Jsc.
Finally, a novel, high-throughput, combinatorial approach for the synthesis and screening of mixed-metal oxides for use as water-splitting photocatalysts was developed. The methodology relies on inkjet printing to form quantitative mixtures of aqueous metal oxide precursors. After pyrolysis, the photoelectrochemical properties of metal oxides can be fully characterized in an automated high-speed system, including measurement of the Voc and J-E curves.
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Lee, Yu-Tsu, and 李佑祖. "Nanometer metal oxide layer on silicon for heterojunction solar cells." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/17640680040796321517.
Full textAbstract:
博士國立中興大學
電機工程學系所
105
We demonstrated a high performance Si-organic hybrid heterojunction solar cell utilizing low temperature and liquid phase-processed TiO2 as an interlayer between PEDOT:PSS and Si nanoholes to produce a conformal contact on the surface of the Si nanostructure. The hydrophilic TiO2/Si-nanohole surface enabling the PEDOT:PSS to flow into the spacing of the close-packed nanoholes. SEM images are use to confirm the PEDOT:PSS nanohole filling induced by the TiO2. With forming gas annealing of the double-sided TiO2, high Voc (0.63 V) and Jsc (35.7 mA/cm2) are obtained, yielding a high power conversion efficiency of 14.7%. The high Voc are attributed to the surface passivation of Si by annealed TiO2. The XPS investigation at the TiO2/Si interface indicates the TiOx signal decreased and the TiO2 and SiOx signals increased after annealing. The Si–O bonding found in the O1s study appeared in the form of Si–O–Si bonding to serve surface passivation. The band alignment of the PEDOT:PSS/TiO2/n-Si hetero-interfaces is postulated and plotted. The Vbi in the system after annealing was assumed to be higher because of the reduction of bulk and surface states that yield high Voc. After annealing, the Vbi increased from 0.805 to 0.905 V. The reduction of surface recombination velocity proved the passivation ability of TiO2 after annealing. With proven surface passivation and conformal PEDOT:PSS/Si nanohole interfaces for enhanced contact, this Si-organic hybrid heterojunction solar cell with solution-processed TiO2 interlayers has excellent potential for application as a high-efficiency and low-cost Si solar cell.
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"Utilization of metal oxide cathode interfacial layer on donor/acceptor solar cells." Thesis, 2011. http://library.cuhk.edu.hk/record=b6075454.
Full textAbstract:
Wang, Mingdong.Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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Bersch, Eric. "Energy level alignment in metal/oxide/semiconductor and organic dye/oxide systems." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17431.
Full text
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Han-QiShangguan and 上官翰琦. "Metal Oxide Electrode-Interlayer in Organolead Iodide Perovskite-Based Solar Cells." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/p6gky9.
Full textAbstract:
碩士國立成功大學
光電科學與工程學系
104
In the past five years, organometal halide perovskite were identified as promising absorbers for solar cells. Although the power conversion efficiencies of perovskite solar cells have rapidly risen to over 20%, there is much room for further improvenment in efficiencies and stability through development of novel materials. Here, we use matel oxide materials, NiOx and ZnO, to substitute PEDOT:PSS and C60 as the hole transport layer and electron transport layer in regular structure planar heterojunction perovskite solar cells. Replacing PEDOT:PSS with NiOx, the efficiencies of devices raised up to over 14%. Replacing C60 with ZnO which was deposited by thermal evaporator, the efficiencies of devices came to be 2.63%. After introducing C60 as a blocking layer, the efficiencies of devices raised up to over 4.55%. We deposited the ZnO films by sputtering and introduced the LiF as the blocking layer because sputtering ZnO film destroyed the perovskite films. We confirmed the blocking layer protected the perovskite layer.