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Banyamin, Ziad. "Novel photovoltaic solar power generating diode." Thesis, Manchester Metropolitan University, 2014. http://e-space.mmu.ac.uk/550063/.
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Thin film solar cells are based on semiconductor materials which are configured together to form a single p-n junction. The p-n junction diode is effectively a simple device that has the capacity to absorb part of the sunlight spectrum and deliver the absorbed photon energy to carriers of electrical current known as electrons and holes. A simple p-n junction solar cell device consists of a p-n junction, a metallic grid and a back contact. The aim of this project was to develop and fabricate a p-n heterojunction diode that is robust, developed with low cost and suitable for large surface area. The device attains a heterojunction configuration, consisting of two thin films, each exhibiting different semiconducting behaviour, namely n-type and p-type semiconductors that are brought together to form a p-n junction diode device. The initial stage of this research was to make and characterise a range of oxide coating compositions that can be sputtered from blends of loosely packed powder targets, using the pulsed DC magnetron sputtering technique. These compositions include fluorine doped tin oxide, antimony doped tin oxide and titanium oxide. The different coatings should be transparent conductive oxides (TCO) that exhibit an n-type semiconductor material characteristic. The second objective was to characterise and develop a p-type semiconductor namely copper aluminium oxide to investigate the optimum compositional ratio and the effect of deposition power on the structure of the thin films. The thin films were characterised in terms of their structural, morphological, optical (transmission and band-gap) and electrical (resistivity, mobility and carrier concentration) conditions. The collection of the charge carriers generated from the incident light was achieved through metal ohmic contacts. This was deposited onto both sides of the device using copper and the silver grids/contacts that are deposited onto the n-type layer and the p-type layers, respectively. The design layout of the grid was optimised in order to increase the device efficiency. The final part of this project was to construct the p-n junction device, test the electrical (current-voltage characteristics) performance and investigate the rectifying behaviour and the formation of the p-n junction.
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Ma, Xi. "One-diode photovoltaic model parameter extraction based on Soft-Computing Approaches." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-36302.
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Thesis explores the question of whether one-diode model can be extracted using soft-computing approaches based on indoor conditions. In thesis, three algorithms were selected using MATLAB for implementation, analysis and comparison. Thesis has proved that under indoor conditions, all three algorithms can accurately extract photovoltaic parameters under most illumination levels, but the extracted photovoltaic parameters cannot satisfy the physical meaning of photovoltaic parameters.
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Chocholáč, Jan. "Využití bypassových diod ve fotovoltaických panelech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218888.
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This thesis deals with usage of bypass diodes in photovoltaic panels. Familiarize us with principles of photovoltaic modules and functions, their electrical characteristics and features. The central objective of this work is description of influence of bypass diodes on particularly shading photovoltaic panels and its volt-ampere characteristics. By the help of created software in Agilent VEE 8.0 simulate the shading panel and compare with real measurement.
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Gallardo, Saavedra Sara. "Analysis and simulation of shading effects on photovoltaic cells." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21725.
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The usage of conventional energy applications generates disproportionate emissions of greenhouse gases and the consumption of part of the energy resources available in the world. It has become an important problem which has serious effects on the climatic change. Therefore, it is crucial to reduce these emissions as much as possible. To be able to achieve this, renewable energy technologies must be used instead of conventional energy applications. Solar Photovoltaic (PV) technologies do not release greenhouse gas emissions directly and can save more than 30 million tonnes of carbon per exajoule of electricity generated relative to a natural gas turbine running at 45% efficiency. Shadowing is one of the most important aspects that affects the performance of PV systems. Consequently, many investigations through this topic are being done in order to develop new technologies which mitigate the impact of shadowing during PV production. In order to minimise the impact of shadowing it is desired to be able to predict the performance of a system with PV-modules during shadowing. In this thesis a simulation program for calculating the IV-curve for series connected PV-modules during partial shadowing has been developed and experimentally validated. PV systems modelling and simulation in LTspice environment has been presented and validated by means of a comparative analysis with the experimental results obtained in a set of tests performed in the laboratory of Gävle University. Experimental measurements were carried out in two groups. The first group corresponds with the experiments done in the string of six modules with bypass diodes while the measurements of the second group have been performed on a single PV module at HIG University. The simulation results of both groups demonstrated a remarkable agreement with the experimental data, which means that the model designed at LTspice supposes a very useful tool that can be used to study the performance of PV systems. This tool contributes to the investigations in this topic and it aims to benefit future installations providing a better knowledge of the shading problem. The master’s thesis shows an in-depth description of the required method to design a PV cell, a PV module and a PV array using LTspice IV and the input parameters as well as the needed tests to adjust the models. Moreover, it has been carried out a pedagogical study describing the effect that different shadow configurations have in the performance of solar cells. This study facilitates the understanding of the performance of PV modules under different shadowing effects. Lastly, it has also been discussed the benefits of installing some newer technologies, like DC-DC optimizers or module inverters, to mitigate the shadowing effects. The main conclusion about this topic has been that although most of the times the output power will be increased with the use of optimizers sometimes the optimizer does not present any benefits.
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Pendyala, Raghu Kishore. "Automated Simulation of Organic Photovoltaic Solar Cells." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15338.
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This project is an extension of a pre-existing simulation program (‘Simulation_2dioden’). This simulation program was first developed in Konarka Technologies. The main purpose of the project ‘Simulation_2dioden’ is to calibrate the values of different parameters like, Shunt resistance, Series resistance, Ideality factor, Diode current, epsilon, tau, contact probability, AbsCT, intensity, etc; This is one of the curve fitting procedure’s. This calibration is done by using different equations. Diode equation is one of the main equation’s used in calculating different currents and voltages, from the values generated by diode equation all the other parameters are calculated.
The reason for designing this simulation_2dioden is to calculate the values of different parameters of a device and the researcher would know which parameter effects more in the device efficiency, accordingly they change the composition of the materials used in the device to acquire a better efficiency. The platform used to design this project is ‘Microsoft Excel’, and the tool used to design the program is ‘Visual basics’. The program could be otherwise called as a ‘Virtual Solar cell’. The whole Virtual Solar cell is programmed in a single excel sheet.
An Automated working solution is suggested which could save a lot of time for the researchers, which is the main aim of this project. To calibrate the parameter values, one has to load the J-V characteristics and simulate the program by just clicking one button. And the parameters extracted by using this automated simulation are Parallel resistance, Series resistance, Diode ideality, Saturation current, Contact properties, and Charge carrier mobility.
Finally, a basic working solution has been initiated by automating the simulation program for calibrating the parameter values.
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Alqahtani, Ayedh H. A. S. "Modeling and Control of Photovoltaic Systems for Microgrids." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1381786869.
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Valent, Adam. "Jednosměrná sériová komunikace laserem na větší vzdálenost." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442524.
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The subject of this thesis is the construction of one-way communication device. This device consists of the transmitter and the receiver, both of which are connected to its respective computer via USB interface. This device allows sending UTF-8 characters or files from one computer to another. Both computers are running a graphical user interface program. The core of a transmitter is a digital signal modulating laser diode. The receiver is made of photovoltaic panel with a resonance circuit and an amplifier. Communication between the electronics and the computer is driven by microcontrollers. Received messages are verified with one of multiple error detection algorithms, which can be selected by user in the utility program.
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Schalnat, Matthew Craig. "Spectroscopic Srudies of Model Organic Photovoltaic and Organic Light Emitting Diode Organic-Organic' and Metal-Organic Heterojunctions." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194656.
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The purpose of this Dissertation was to present fundamental approaches to expand the general knowledge of the chemistry that occurs at both the organic-organic' (O-O') and the metal-organic (M-O) interfaces in organic optoelectronic devices. In order to simplify the interactions in the initial studies presented herein, simple model molecules that represent the larger, highly conjugated molecules used in device construction were considered.UPS, reductive-desorption electrochemistry, and Raman surface spectroscopy were used to determine monolayer characteristics of thiophenol and pentafluorothiophenol on Ag. Proposed interfacial orientations and molecular spacing of the TP and F5TP were proposed. Benzene and hexafluorobenzene (F6-benzene) were then condensed and forcibly dewet onto the monolayers in an effort to understand the solid-liquid interfacial interactions. Benzene films on alkanethiol (UDT) and perfluorinated thiophenol (F5TP) were prone to rupturing, and spectroscopically appeared to be liquid-like in character, while molecular spacing of TP and adsorbed benzene on unmodified Ag template ordered benzene films. Polycrystalline films of F6-benzene forms at the interfaces of TP and unmodified substrates. F6-benzene induces a reorientation of F5TP molecules, but is subsequently unable to induce long range order. F6-benzene on UDT appears liquid-like. These studies show that fixed molecules can stimulate order or disorder at a molecular heterojunction, which may have profound effects in device efficiency.In an effort to begin to understand the complicated reaction chemistry that occurs at the organic-metal interfaces in optoelectronic devices, thin benzene films were reacted with typical device cathode metals, Ag, Mg, Al, and Ca, and studied using Raman vibrational spectroscopy. Ag and Mg form metal clusters and some adduct formation. Al undergoes an insertion reaction, forming a substituted benzene ring. Ca reacts with benzene to form a phenyl radical, which then decomposes the film into regions of ordered graphitic carbon. The results of these studies are attributed to atomic properties of the metal atoms.
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John, Suru Vivian. "Next generation bulk Heterojunction organic Photovoltaic and light emitting diode sytems of Novel Polycyclic Aromatic Hydrocarbon, Polyfluorenes and Polythiophenes." University of the Western Cape, 2017. http://hdl.handle.net/11394/6114.
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Philosophiae Doctor - PhD (Chemistry)In these times of diminishing reserve of fossil fuel, the development of novel - green or renewable? technologies to meet the increasing worldwide demand for energy is of great importance. The sun is the largest carbon free source of energy and an infinite source of renewable energy. However, except for the expensive inorganic crystalline silicon photovoltaic cells, this source of energy has not been utilized. The field of organic photovoltaic cell has made impressive progress in the last few years with the tremendous efforts of researchers working tirelessly to develop organic materials for solar energy conversion. Organic conjugated materials have the advantage of low cost, light weight, process-ability and good flexibility over inorganic materials. They have attracted wide academic and industrial interest due to their promise as semiconductors for photovoltaic applications. Design of advanced organic conjugated materials with the ability to absorb light from the sun and convert it into useful and storable form has and still is one of the most important goals of researchers in the field of renewable energy. This work describes a number of novel exciting and promising materials based on polycyclic aromatic compounds (PACs) for organic photovoltaic cells and organic light emitting diodes.
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Kozlowski, Fryderyk. "Numerical simulation and optimisation of organic light emitting diodes and photovoltaic cells." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1134592504212-65990.
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A numerical model and results for the quantitative simulation of multilayer organic light emitting diode (OLED) and organic solar cell (OSC) are presented. In the model, effects like bipolar charge carrier drift and diffusion with field-dependent mobilities, trapping, dopants, indirect and direct bimolecular recombination, singlet Frenkel exciton diffusion, normal decay and quenching effects are taken into account. For an adequate description of multilayer devices with energetic barriers at interfaces between two adjacent organic layers, thermally assisted charge carrier hopping through the interface, interface recombination, and formation of interface charge transfer (CT) states have been introduced in the model. For the simulation of OSC, the generation of carrier pairs in the mixed layer or at the interface is additionally implemented. The light absorption profile is calculated from optical simulations and used as an input for the electrical simulation. The model is based on three elements: the Poisson equation, the rate equations for charge carriers and the rate equations for singlet Frenkel excitons. These equations are simultaeously solved by spatial and temporal discretisation using the appropriate boundary conditions and electrical parameters. The solution is found when a steady state is reached, as indicated by a constant value of current density. The simulation provides a detailed look into the distribution of electric field and concentration of free and trapped carriers at a particular applied voltage. For organic light emitting diodes, the numerical model helps to analyze the problems of different structures and provides deeper insight into the relevant physical mechanisms involved in device operation. Moreover, it is possible to identify technological problems for certain sets of devices. For instance, we could show that ? in contrast to literature reports - the contact between Alq3 and LiF/Al did not show ohmic behaviour for the series of devices. The role of an additional organic blocking layer between HTL and EML was presented. The explanation for the higher creation efficiency for singlet excitons in the three-layer structure is found in the separation of free holes and electrons accumulating close to the internal interface 1-Naphdata/Alq3. The numerical calculation has demonstrated the importance of controlled doping of the organic materials, which is a way to obtain efficient light emitting diodes with low operating voltage. The experimental results has been reproduced by numerical simulation for a series of OLEDs with different thicknesses of the hole transport layer and emitting layer and for doped emitting layers. The advantages and drawbacks of solar cells based on flat heterojunctions and bulk heterojunctions are analyzed. From the simulations, it can be understood why bulk-heterojunctions typically yield higher photocurrents while flat heterojunctions typically feature higher fill factors. In p-i-n ?structures, p and n are doped wide gap materials and i is a photoactive donor-acceptor blend layer using, e.g,. zinc phthalocyanine as a donor and C60 as an acceptor component. It is found that by introducing trap states, the simulation is able to reproduce the linear dependence of short circuit currents on the light intensity. The apparent light-induced shunt resistance often observed in organic solar cells can also be explained by losses due to trapping and indirect recombination of photogenerated carriers, which we consider a crucial point of our work. However, these two effects, the linear scaling of the photocurrent with light intensity and the apparent photoshunt, could also be reproduced when field-dependent geminate recombination is assumed to play a dominant role. First results that show a temperature independent short circuit photocurrent favour the model based on trap-mediated indirect recombination.
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Diac, Andreea Petronela. "Design, synthesis and supramolecular architectures of new heterocyclic compounds with potential applications in material chemistry and photovoltaic conversion." Thesis, Angers, 2015. http://www.theses.fr/2015ANGE0019/document.
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La thèse intitulée «Design, Synthesis and SupramolecularArchitectures of New Heterocyclic Compounds with PotentialApplications in Material Chemistry and Photovoltaic Conversion” eststructurée en cinq chapitres traitant de nouveaux: a)cyclopenta[c]pyrannes hétérocyclique; b)des propriétés fluorescentes; d) potentiels dispositifs de l'électroniquemoléculaire; d) donneurs moléculaires pour les photovoltaïquesorganiques et e) carbon‘quantum’dots électroluminescents.Le premier chapitre présente une étude des dérivéspseudoazulenique ayant une unité cyclopenta[porte sur leur synthèse, l'analyse structurale et leur comportement dansdes réactions de substitution électrophile pour obtenir des composésayant des propriétés fluorescentes.Le deuxième chapitre présentediastéréoisomères et l'étude de propriétés de fluorescencedérivés d’indenopyrone.Le troisième chapitre décrit la synthèse des nouvellesarchitectures basées sur l’unité cyclopenta[être modifiés structurellement par l'influence d'un stimulus chimiqueou électrochimique afin d'élaborer des potentiels dispositifs del'électronique moléculaire.Dans le quatrième chapitre, la synthèsedes propriétés électroniques des nouvelles molécucellules solaires organiques (OSC) ontLe cinquième et dernier chapitre décrit la passivation desdéfauts de surface des nanoparticules de carbone avec desmolécules organiques ou des polymères pour obtenir desnanoparticules de carbone photoluminescentse surnommé ‘quantum dotsThe thesis entitled “Design, Synthesis and SupramolecularArchitectures of New Heterocyclic Compounds with PotentialApplications in Material Chemistry and Photovoltaic Conversion” isstructured into five chapters concerning new: a) heterocycliccyclopenta[c]pyrans; b) indenopyrone derivatives with fluorescentproperties; c) potential devices of molecular electronics; d)donors for organic photovoltaics and e) electroluminescent carbon‘quantum’ dots.The first chapter presents a study of pseudoazulenederivatives having a cyclopenta[c]pyran unit. The survey comprises thesynthesis, structural analysis and reactivity towards electrophilicsubstitution in order to obtain fluorescent compounds.The second chapter deals with the separation odiastereoisomers and the study of fluorescent propertiesindenopyrone derivatives.The third chapter describes the synthesis of newarchitectures based on cyclopenta[c]pyran unit that can be structurallymodified by the influence of a chemical or electrochemical stimulus inorder to work as potential devices in molecular electronics.In the fourth chapter, the synthesis andelectronic properties of new molecular donors for organic solar cellswas described.The fifth and last chapter outlines the passivation of surfacedefects on carbon nanoparticles using small organic molecules orpolymers in order to obtain photoluminescent carbon nanoparticlesdubbed as carbon‘quantum’dots
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Pugsley, Adrian Nicholas. "Theoretical and experimental analysis of a novel flat photovoltaic-thermal solar water heater with integrated energy storage via a planar liquid-vapour thermal diode." Thesis, Ulster University, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713462.
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Photovoltaic thermal (PVT) solar collectors generate heat and electricity. Building Integrated (BI) facade collectors are suited to high rise buildings. Ulster University researches novel Integrated Collector-Storage Solar Water Heaters (ICSSWH). This study investigates Planar Liquid-Vapour Thermal Diode (PLVTD) heat transfer and characterises performance of a BIPVT-PLVTD-ICSSWH prototype. A thermal resistance network representing evaporation, vapour transfer, condensation, fluid conduction and convection, plate-to plate radiation, and solid conduction is established and evaluated using Stefan-Boltzmann and Fourier laws together with Rayleigh/Reynolds-Nusselt and Rohsenow correlations.
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Snaith, Henry James. "Polymer based photovoltaic diodes." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614761.
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Zhao, Baodan. "Halide perovskites for photovoltaics and light-emitting diodes." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289450.
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Halide perovskite solar cells, with rapid efficiency improvements from ~10% to ~23% in 6 years, have attracted significant attention due to their remarkable performance, low processing cost and their potential to become a strong alternative candidate to silicon solar cells. Significant development has also been achieved in halide perovskite-based LEDs with EQE improved from below 1% to ~20% in less than 4 years. This remarkable progress can mainly be attributed to the optimisation of halide perovskite properties. This dissertation focuses on the correlation between optical and electrical properties of halide perovskites and their remarkable performance. Bandgap tunabilities of halide perovskites in blue to green regions through mixing Br-and Cl-and in near infra-red region by substituting Pb2+ with Sn2+ are demonstrated. The absorption and PL spectra are consistent with each other supporting the bandgap tunability. Corresponding EL spectra, which are consistent with their PL spectra, are also demonstrated for blue to green regions. Terahertz measurements coupled with PLQE and transient PL results reveal that the high carrier mobilities are the main reason behind the high efficiency of tin-rich samples. A novel perovskite-polymer-bulk heterostructure is introduced and studied comprehensively. Correlations between their optoelectronic properties and remarkable performance on timescales ranging from femtosecond to microsecond are presented. Transient optical spectroscopy reveals the energy transfer from 2D regions to 3D regions happens in 1 ps. The 20% EQE of the LEDs based in this structure is consistent with conventional thin-film optical models giving internal quantum efficiency of ~100%. This in agreement with near-unity PLQE value of the pristine emissive layer material and the dominant bimolecular recombination process observed in nanosecond-scale transient PL measurements. Two typical interfacial engineering methods to improve the quality of halide perovskite and device performance are then presented. Optimised NiOx is adopted to improve the anode interface. From transient photovoltaic measurements, we find the charge collection ability of NiOx is superior to that of PEDOT:PSS. This is also the main reason behind their better photovoltaic device performance. A unique anti-solvent treatment with additive modifies both the bulk and surfaces of halide perovskites and improves the device performance significantly. Transient PL and PLQE measurements demonstrate that non-radiative recombination pathways are significantly reduced.
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Chow, Philip Chi Yung. "Time-resolved optical studies of excited states in organic photovoltaic diodes." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708343.
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Messanvi, Agnès. "Composants photoniques à base de fils de nitrures d'élément III : du fil unique aux assemblées." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY062/document.
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Cette thèse porte sur la réalisation de composants photoniques à base de fils de nitrures III-V. Les fils de GaN non-catalysés ont été élaborés de manière auto-assemblée par épitaxie en phase vapeur aux organométalliques (MOVPE) sur saphir. Un des axes de ce travail a porté sur la croissance organisée de ces fils à travers un réseau d’ouvertures défini par lithographie et gravure d’une couche de SiNx. Nous avons étudié en particulier l’influence des paramètres de croissance (température, pression, ratio V/III) et du motif sur l’homogénéité de la croissance sélective. Ces fils ont servi de substrat pour la croissance d’hétérostructures radiales cœur-coquille InGaN/GaN.D’autre part, la croissance, la fabrication et les propriétés physiques de trois types de composant ont pu être étudiées :-Des cellules solaires à fils uniques. Nous avons comparé l’efficacité de conversion de deux types d’hétérostructures : des coquilles épaisses d’In0.1Ga0.9N et des coquilles à 15 et 30 puits quantiques In0.18Ga0.82N/GaN. Après optimisation du contact électrique sur la coquille p-GaN, un rendement maximal de 0,33 % a été obtenu avec des fils à 30 puits quantiques sous éclairement équivalent à 1 soleil (AM1.5G). Le seuil d’absorption mesuré par spectroscopie de photocourant varie entre 400 et 440 nm.- Une plateforme émetteur-détecteur. Le système, qui fonctionne à 400 nm, comprend deux fils de GaN à hétérostructure radiale InGaN/GaN positionnés sur le même substrat et couplés par un guide d’onde en SiNx. La caractérisation électrique du dispositif a mis en évidence une durée de commutation inférieure à 0,25 s sans photocourant persistant.- Des diodes électroluminescentes (LED) flexibles. Ces diodes qui émettant dans le visible (400-470 nm) ont été réalisées en se basant sur une approche hybride organique/inorganique. Les fils émetteurs à puits quantiques InGaN/GaN sont encapsulés dans une matrice organique de PDMS puis détachés de leur substrat de croissance. Les contacts sont réalisés à partir de nanofils d’argent qui présentent l’avantage d’être à la fois flexibles, transparents et conducteurs. A partir de ce procédé, une LED bicolore flexible a été réalisée en combinant des émetteurs bleus et « verts »This thesis reports on the realization of photonic devices based on nitride wires. Self-assembled GaN wires were grown without catalyst by metal-organic vapor phase epitaxy (MOCVD) on sapphire substrates. Part of this work focused on the selective area growth of GaN wires through a dielectric SiNx mask with regular arrays of holes defined by lithography and dry etching. We studied the influence of the growth conditions (temperature, pressure, V/III ratio) and pattern geometry on the homogeneity of the selective area growth. These wires were used as templates for the growth of core-shell InGaN/GaN heterostructures. In addition, the growth, microfabrication process and properties of three types of devices were studied:- Single wire solar cells. We compared the efficiency of two type of heterostructures: shells composed of thick In0.1Ga0.9N layers and In0.18Ga0.82N/GaN quantum wells. After optimization of the electrical contact on the p-GaN shell, a maximal conversion efficiency of 0,33 % was obtained on single GaN wires with a shell of 30 quantum wells under 1 sun illumination (AM1.5G). Photocurrent spectroscopy revealed that the wire absorption edge varied between 400 and 440 nm.- An integrated photonic platform. The system, that operates around 400 nm, is composed of two GaN wires with radial InGaN/GaN heterostructures positioned on the same substrate and coupled with a SiNx waveguide. The electrical characterization of the platform revealed a switching speed inferior to 0.25 s without persistent photocurrent.- Flexible light emitting diodes (LED). The LED fabrication is based on a dual approach which associates inorganic InGaN/GaN emitters (400-470 nm) and a polymer. The wires are encapsulated in a PDMS matrix before being detached from their native substrate. Electrical contacts are made with silver nanowires which are flexible, highly conductive and transparent in the visible range. Based on this procedure a two-color LED was realized by stacking a blue and a “green” LED
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Gonzalez-Rabade, A. "Correlation of heterojunction luminescence and photocurrent in polymer blend photovoltaic diodes." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599488.
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This thesis focuses on the electronic and photophysical phenomena that occur at the heterojunction between two distinct organic semiconductor materials. The hetero junction luminescence is correlated to the photovoltaic performance in a polymer blend diode. Polymer semiconductor blends allow efficient operation of photovoltaic diodes when there is a large interfacial area of hetero junction between electron donor and acceptor polymers. In this thesis, we use electromodulation spectroscopy to investigate the luminescent and photovoltaic behaviour of electron- and hole-transporting polyfluorenes blends at a broad range of blend ratios, temperatures and electric fields. In the systems investigated, an exciton at the hetero junction produces either free charges or an exciplex (or a similar interfacially-bound charge-transfer pair). We find that an externally-applied electric field increases the number of free charges and quenches the exciplex luminescence with a one-to-one correspondence: the increase of the photocurrent internal quantum efficiency is equal to the reduction in the exciplex emission. We conclude that, independent of temperature and morphology, the photovoltaic quantum yield is predominantly limited by the dissociation of the geminate electron-hole pair intermediate at the hetero junction. Once the charges are fully separated they are transported across the material and collected at the external circuit with nearly unit efficiency.
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Zheng, Ying. "Nanostructured thin films for organic photovoltaic cells and organic light-emitting diodes." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024921.
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Dus, Ondřej. "Vliv zastínění na parametry solárních modulů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217647.
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Singh, Priyanka O. "Modeling of Photovoltaic Arrays under Shading Patterns with Reconfigurable Switching and Bypass Diodes." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321559036.
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Baura, Tomáš. "Analýza fotovoltaických článků pomocí fotoluminiscence." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219874.
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This thesis deals with the analysis of solar cells by photoluminescence method. Photoluminescence method is based on the excitation of luminescence radiation of the solar cell material by an external excitation light source. This method can detect various types of defects in the material solar cells. The main objective is the design and realization of a measuring system defects of solar cells, which is based on this method. For excitation of luminescence is used LED array. For the detection of luminescence is used CCD camera with IR optical filter. To filter out the excitation light radiation is used disc screen and optical interrupter. The parameters and options of this measuring system are verified and characterized by test measuring for example the achievable rotation speed of screen and response of optical interrupter. At the end is tested detection of luminescence radiation of solar cells in the measuring system. The measured images are compared with the method of electroluminescence.
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Deng, Wenpeng. "A solar PV-LED lighting system with bidirectional grid ballasting." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709190.
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陳土培 and Tupei Chen. "Studies of metal - semiconductor contacts: current transport, photovoltage, schottky barries heights and fermi level pinning." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31233491.
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Chen, Tupei. "Studies of metal - semiconductor contacts: current transport, photovoltage, schottky barries heights and fermi level pinning /." [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13814254.
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Selzer, Franz, Nelli Weiß, David Kneppe, Ludwig Bormann, Christoph Sachse, Nikolai Gaponik, Alexander Eychmüller, Karl Leo, and Lars Müller-Meskamp. "A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36329.
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We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □−1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.
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Ho, Kai Wai. "Evaluation and characterization of efficient organic optoelectronic materials and devices." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/816.
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With the progression towards lighter but larger-display self-sustainable mobile devices, device efficiency becomes increasingly important, owing to the higher power display consumption but at the same time more limitation on the size and volume of energy storage. In this thesis, selected aspects regarding to efficiency of three types of optoelectronic devices, indoor photovoltaics (IPVs), perovskite thin-film transistors (TFTs) and organic light-emitting diodes (OLEDs) have been investigated. IPVs can make off-grid devices self-sustainable by harvesting ambient light energy. Its weak irradiance necessitates high-efficiency IPVs to generate sufficient power. Our work addresses the need of knowing the limit of the device parameters for correct evaluation and understanding the efficiency loss for developing clinical tactics. We delivered a general scheme for evaluating the limiting efficiency and the corresponding device parameters of IPVs under various lights, illuminance and material bandgap. In contrast to the AM1.5G conditions, a maximum power conversion efficiency (PCE) of 51-57 % can be achieved under the optimal bandgap of 1.82-1.96 eV. We also propose using the second thickness peak of interference instead of the first as a better optimal absorber thickness after identifying the finite absorption as the major source of efficiency loss. The work provides insights for device evaluation and material design for efficient IPV devices. The novel hybrid organic-inorganic perovskites have gained enormous research interest for its various excellent optoelectronic properties such as high mobility. TFT as an alternative application to the majorly focused photovoltaics is realized in this work. There are few reports on perovskite TFTs due to wetting issues. By employing polymethacrylates with ester groups and aromatic substituents which provide polar and cation-π interactions with the Pb2+ ions, quality films could be fabricated with large crystals and high electron mobility in TFTs. We further improved the performance by resolving interfacial mixing between the perovskite and the polymer using the crosslinkable SU-8, achieving the highest mobility of 1.05 cm2 V−1 s−1. Subsequently, we cured the grain boundaries using methylamine solvent vapor annealing, suppressing the TFT subthreshold swing. The work provides a map for the improvement of perovskite TFTs. It has been revealed that molecular orientations of the emitters in OLEDs with the transition dipole moment lying in plane enhances light outcoupling efficiency. Multiple experimental techniques are needed to provide complementary orientation information and their physical origin. Here, we propose using TFT to probe the orientation of the phosphorescent emitters. Homoleptic fac-Ir(ppy)3 and heteroleptic trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) were deposited on polystyrene (PS) and SiO2 substrates. Compared to the PS surface inducing isotropic orientation as the control, trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) possessed decreased carrier mobilities on SiO2. With the study of initial film growth, we infer that preferred orientation induced by the polar SiO2 surface led to an increase in energetic disorder in the well-stacked trans-Ir(ppy)2(acac) and hopping distance in the amorphous trans-Ir(ppy)2(tmd). The highly symmetric fac-Ir(ppy)3 remained its isotropic orientation despite the dipolar interaction. Surprisingly, the TFT technique gives much higher sensitivity to surface-induced orientation, and thus may potentially serve as a unique electrical probe for molecular orientation.
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Ho, Ka Wai. "Evaluation and characterization of efficient organic optoelectronic materials and devices." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/873.
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With the progression towards lighter but larger-display self-sustainable mobile devices, device efficiency becomes increasingly important, owing to the higher power display consumption but at the same time more limitation on the size and volume of energy storage. In this thesis, selected aspects regarding to efficiency of three types of optoelectronic devices, indoor photovoltaics (IPVs), perovskite thin-film transistors (TFTs) and organic light-emitting diodes (OLEDs) have been investigated. IPVs can make off-grid devices self-sustainable by harvesting ambient light energy. Its weak irradiance necessitates high-efficiency IPVs to generate sufficient power. Our work addresses the need of knowing the limit of the device parameters for correct evaluation and understanding the efficiency loss for developing clinical tactics. We delivered a general scheme for evaluating the limiting efficiency and the corresponding device parameters of IPVs under various lights, illuminance and material bandgap. In contrast to the AM1.5G conditions, a maximum power conversion efficiency (PCE) of 51-57 % can be achieved under the optimal bandgap of 1.82-1.96 eV. We also propose using the second thickness peak of interference instead of the first as a better optimal absorber thickness after identifying the finite absorption as the major source of efficiency loss. The work provides insights for device evaluation and material design for efficient IPV devices. The novel hybrid organic-inorganic perovskites have gained enormous research interest for its various excellent optoelectronic properties such as high mobility. TFT as an alternative application to the majorly focused photovoltaics is realized in this work. There are few reports on perovskite TFTs due to wetting issues. By employing polymethacrylates with ester groups and aromatic substituents which provide polar and cation-π interactions with the Pb2+ ions, quality films could be fabricated with large crystals and high electron mobility in TFTs. We further improved the performance by resolving interfacial mixing between the perovskite and the polymer using the crosslinkable SU-8, achieving the highest mobility of 1.05 cm2 V−1 s−1. Subsequently, we cured the grain boundaries using methylamine solvent vapor annealing, suppressing the TFT subthreshold swing. The work provides a map for the improvement of perovskite TFTs. It has been revealed that molecular orientations of the emitters in OLEDs with the transition dipole moment lying in plane enhances light outcoupling efficiency. Multiple experimental techniques are needed to provide complementary orientation information and their physical origin. Here, we propose using TFT to probe the orientation of the phosphorescent emitters. Homoleptic fac-Ir(ppy)3 and heteroleptic trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) were deposited on polystyrene (PS) and SiO2 substrates. Compared to the PS surface inducing isotropic orientation as the control, trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) possessed decreased carrier mobilities on SiO2. With the study of initial film growth, we infer that preferred orientation induced by the polar SiO2 surface led to an increase in energetic disorder in the well-stacked trans-Ir(ppy)2(acac) and hopping distance in the amorphous trans-Ir(ppy)2(tmd). The highly symmetric fac-Ir(ppy)3 remained its isotropic orientation despite the dipolar interaction. Surprisingly, the TFT technique gives much higher sensitivity to surface-induced orientation, and thus may potentially serve as a unique electrical probe for molecular orientation.
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Nylund, Sophie, and Zahra Barbari. "Study of defects in PV modules : UV fluorescence and Thermographic photography for Photovoltaics (PV) Field Application." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-44120.
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For a PV plant it is of fundamental importance that the operation of the PV modules is free from faults or at least that the faults can be detected early, to ensure efficient electricity production. Some defects such as cracks can be seen in visible light while microcracks and damage to the silicon material can only be seen through special lighting. This study focuses on the most common defects in photovoltaic (PV) systems. Compare the infrared (IR) technology with the new ultraviolet (UV) fluorescence image technique for PV characterization, based on their accuracy and uncertainty factors under an experimental field investigation. In this study, first a literature study was conducted to the most common defects in PV system and their impact on electricity generation. Then a simulation model of a PV system was created in PVsyst and exported to Microsoft Excel which was used to evaluate how different defects at different stages of the PV cell's life cycle impact electricity generation, performance parameters and economic exchange. Furthermore, experiments with UV and IR was implemented at a PV system located in Dalarna and some PV modules at MDH. It was conducted that occurrence of snail tracks, delamination and hot spots in combination with bypass failures and non-functioning cell will affect the economic profitability in the long run and the payback time will increase since their impacts on electricity generation and performance parameters are huge. The worst case is when PV modules are affected by the fault in bypass diode and non-functioning cell which result to a payback time longer than the module's lifetime and huge amount electricity losses in different bypass diodes configurations. Since UV and IR are two different methods that are performed in two different ways, different errors occurred during the measurements. The biggest external factor was the weather that determined if the experiment could be implemented. The IR method gave decent results and was quicker to use, but the UV method highlighted some defect which could not be seen with the IR technology.
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Li, Juo-Hao. "A study of interfaces between organic and metal materials and their application in polymer light-emitting diodes and polymer photovoltaic solar cells." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835419051&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Radić, Aleksandar. "Comparative analysis of high input voltage and high voltage conversion ratio step-down converters equipped with silicon carbide and ultrafast silicon diodes." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/861.
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DC to DC step-down applications with high input voltage and high voltage conversion ratio operational requirements, such as photovoltaic battery chargers, are subject to high conduction losses, high switching losses and substantial reverse-recovery losses when minority carrier principle diodes are used. The recent introduction of silicon carbide diodes with high breakdown voltages has made possible the elimination of reverse-recovery losses at high voltage levels and as such has sparked interest in their use due to the potential efficiency improvements.
This report presents the results of a comprehensive analysis on the use of silicon carbide diodes and their counterparts, ultrafast silicon diodes, in conventional buck converters and isolated current-fed buck converters in high input voltage and high voltage conversion ratio step-down applications. The analysis illustrates both theoretically, with the use of steady-state average models, and experimentally the substantial efficiency benefits of the use of reverse-recovery free silicon carbide diodes in the conventional buck converter and the small but significant improvement in the efficiency of the isolated current-fed buck converter. The improvements of the conventional buck converter paired with silicon carbide diodes are shown to be significant enough to grant the variant the most efficient position for power levels below 1 kW. In addition, the four variants are categorized based on their cost and performance; therefore, providing engineers with a convenient guide to aid their selection of the appropriate converter depending on the operational requirements.
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Pospíšil, Jan. "Studium optoelektrických vlastností tenkých vrstev organických polovodičů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216901.
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The thesis is focused on the study of electric and dielectric properties of thin film organic materials that can be used as an active layer of photovoltaic cells. Primarily were studied the properties of the layers on the glass substrates, which consist of a thin active layer of phthalocyanines. On the samples were first measured current-voltage characteristics (in the dark and during the exposure) and the basic parameters of the photovoltaic conversion were determined. Finally were measured frequency dependencies (impedance spectra, in the dark and during the exposure) and the parameters of a model of the structure with organic semiconductor were determined. The obtained results will be used to optimize the properties of photovoltaic cells.
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Hampl, Petr. "Design pouliční svítilny s nezávislým napájením." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228418.
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Oblast problémů, ze kterých konkrétní téma projektu vychází, zahrnuje současnou globální transformaci zdrojů energie a jejich dodávek se zvláštní pozorností na obnovitelné zdroje energie. Důraz je kladen zejména na hodnoty jež přináší produkt určený k užívání ve veřejných prostorách. Autorovým zadáním bylo navrhnout osvětlovací jednotku nezávislou na vnějším zdroji napájení. Cílem návrhu je přehodnotit způsob, jakým jsou dnes technologie využívání sluneční a větrné energie běžně používány, a navrhnout řešení přinášející nové vlastnosti a užitné hodnoty pro přímého uživatele i celou společnost. Autor přináší návrh produktu jenž je reakcí na současné globální hrozby a příležitosti. Výsledkem projektu je návrh pouliční lampy kombinující fotovoltaický článek a větrnou turbínu s cílem získat elektrickou energii jež je dočasně akumulována a následně dodávána svítidlu. V návrhu je kladen důraz na požadavky ergonomie a estetickou hodnotu produktu. Navržené řešení znamená finanční přínos z hlediska šetření neobnovitelnými zdroji energie a případnými finančními výhodami pro investora plynoucími z provozování veřejného osvětlení. Pouliční lampa nezávislá na vnějším zdroji napájení má navíc menší negativní dopad na životní prostředí a představuje technologie využívání větrné a solární energie v přívětivé a nerušivé podobě.
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Brombosz, Scott M. "Alkynylated acenothiadiazoles and N-heteroacenes: synthesis, functionalization, and study of the optical properties for optoelectronic and sensory materials." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37102.
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For organic electronic device applications materials are needed which display good charge carrier mobility, good processability, and stability towards oxygen and moisture. Alkynylated N-Heteroacenes fulfill many of these requirements. Substitution with alkyne groups as well as the introduction of the pyrazine subunit both inhibits oxidative degradation at sensitive position in the molecules. Additionally the trialkylsilylethynyl group aides in directing the packing motif as well as vastly increases the solubility over unsubstituted analogues.
A requisite precursor in the synthesis of alkynylated N-heteroacenes is alkynylated acenothiadiazoles. These thiadiazoles display interesting photophysical properties and can be functionalized to produce a wide range of properties in closely related materials. The acenothiadiazoles themselves have potential applications as an N-type semiconductor. Optical gaps and calculated HOMO-LUMO gaps show that these molecules, when compared to known N-type materials, should be easily injected with electrons. Additionally the crystal packing of these compounds shows favorable π-orbital overlap which should provide excellent charge carrier mobilities.
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Ehré, Florian. "Elaboration et caractérisation de films d'oxynitrure de silicium dopés cérium et ytterbium : applications aux diodes électroluminescentes et au découpage quantique pour les cellules solaires." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC260/document.
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Cette thèse porte sur les applications optiques de films d’oxynitrures de silicium dopés cérium et co-dopés cérium-ytterbium élaborés par pulvérisation cathodique magnétron radiofréquence. Les paramètres de dépôt ont été optimisés afin d’obtenir une intense émission visible à l’œil nu des ions Ce3+ dans la matrice hôte SiOxNy. Il est démontré que le flux d’azote est un paramètre crucial pour obtenir cette émission. Nous avons montré aussi que les ions Ce3+ peuvent être incorporés en grande quantité dans cette matrice, sans clusterisations jusqu’à de très hautes températures de recuits (1200°C). Ces excellentes propriétés optiques ont mené à une première application : la tentative d’élaboration de DEL bleue. Les premiers résultats obtenus montrent une électroluminescence peu intense, mais restent encourageants pour une étude plus approfondie. La deuxième application étudiée est le développement de couches à conversion de fréquence basse pour augmenter le rendement des cellules solaires à base de silicium. En effet les cellules solaires sont limitées par le recouvrement du spectre solaire et la plage d’absorption de la cellule. L’élaboration de films SiOxNy co-dopés Ce/Yb pour convertir un photon ultra-violet (300-400 nm) en deux photons infra-rouges (980 nm) permet de passer outre la limite théorique des cellules solaires. Les systèmes élaborés montrent une émission des ions Yb3+ en présence d’ions Ce3+ dans la matrice hôte SiOxNy. Les ions Ce3+ permettent d’excités les ions Yb3+ sur une large gamme spectrale et le mécanisme de transfert d’énergie entre ces deux terres rares est détaillé. Un rendement de conversion de 185% est obtenu pour la plus forte concentration en ions Yb3+. Pour améliorer ce système, l'ajout de miroirs de Bragg entre la couche à conversion et le substrat de silicium, représentant la cellule solaire, a été étudié théoriquement. Leur but est double : maximiser le flux de photons ultraviolets piégé dans la couche à conversion de fréquence et transmettre un maximum de photons infrarouges, qui sont facilement absorbables, vers la cellule solaireThis thesis is dedicated to cerium doped and cerium-ytterbium co doped oxynitride silicon films optical applications grown by radio frequency magnetron sputtering. Growth parameters have been optimized in order to obtain a strong cerium emission visible to the naked eye in the matrix host SiOxNy, especially the nitrogen flux has a dominant role. We showed that cerium ions have a high solubility without clustering at very high annealing temperature (1200°C). Those excellent properties lead to a first application: the elaboration of blue LED. First results show a weak electroluminescence signal but are still encouraging for further study. The second application is the elaboration of frequency conversion layers to increase the efficiency of Si based solar cell. Indeed solar cell are limited by the mismatch between the solar spectrum and the cell absorption range. The elaboration of Ce/Yb co doped SiOxNy films to convert a UV photon (300-400 nm) into two infrared photons (980 nm) allows to overcome the solar cell theoretical limit. Layers grown show an Yb3+ ion emission in presence of Ce3+ ions in the host matrix SiOxNy. Ce3+ ions sensitize Yb3+ ions on a large spectral range and their cooperative energy transfer mechanism is detailed. An efficiency of 185% is obtained for the higher dopants atomic concentration. In order to improve this system, the effect of adding Bragg mirrors placed between the conversion layer and the silicon substrate, which represents the solar cell, is theoretically studied. Their aim is double: increase the maximum flux of UV photons trapped in the frequency conversion layer and transmit a maximum of infrared photons, which are easily absorbable, toward the solar cell
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Lin, Chung-Han. "The Effects of Thermal, Strain, and Neutron Irradiation on Defect Formation in AlGaN/GaN High Electron Mobility Transistors and GaN Schottky Diodes." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1371466261.
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Lorrière, Nominoë. "Cellules photovoltaïques pour la récupération d'énergie et la communication de données." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0570.
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L’invention des LED bleues de forte intensité en 1993 a permis une révolution générale de l’éclairage pour le grand public aussi bien que pour les commerces. Ces nouveaux dispositifs, proposent un rendement énergétique bien supérieur aux technologies commerciales précédentes, ce qui explique leur déploiement massif depuis la fin des années 2000. Les matériaux semiconducteurs composant les LED sont déjà utilisés dans le domaine de la microélectronique pour effectuer des fonctions logiques à hautes fréquences.La technologie LiFi tend à cumuler ces deux propriétés en ajoutant une fonction de transmission d’information aux points d’éclairages existants. L’information est transmise en modulant l’intensité de la lumière à haute fréquence, bien au delà des capacités distinctives de l’oeil. Cette technologie devrait subir un déploiement avec l’arrivée de l’Internet des Objets (IoT) qui apporte une grande demande de connections sans fil, incompatible avec les réseaux radiofréquences actuels. Le travail présenté ici porte sur la réception de cette modulation lumineuse. Les récepteurs usuellement utilisés sont des photodiodes mais ces dernières imposent des contraintes d’éclairage et de consommation difficilement corrélables avec les impératifs de l’IoT. Ainsi, ces travaux étudient la possibilité de réception de la modulation LiFi par des cellules et modules photovoltaïques, dont les deux principales qualités restent les grandes dimensions du détecteur permettant une omnidirectionnalité de réception et une résistance à l’ombrage ainsi que le caractère passif de la détectionThe invention of high-intensity blue LED hit the market and the retail industry in 1993. It even brought a revolution in lighting history. These new devices significantly improved energy efficiency than ever before and led to their massive deployment since the end of the 2000s. Semiconductor materials for LED devices are used in the microelectronics domain to implement high-frequency logic functions.Light fidelity (LiFi) technologies combine illumination and communication capabilities by implanting information transmission function to existing lighting equipment. Information is transmitted by using intensity modulation of optical sources at high frequencies, far beyond the range of visual perception. LiFi is an enabling technology for the Internet of Things (IoT) systems. IoT requires a large number of wireless connections, so it is not compatible with existing radiofrequency networks.This work is based on the reception of light modulation. Photodiodes are the mostly used receivers, however their constraints on lighting and consumption make it difficult to meet the requirements of the IoT. On the ground of this, this research is aimed at studying the possibility of receiving LiFi modulation by photovoltaic cells and modules due to their two main qualities: passive detection and large dimensions (omnidirectional reception and shade resistance)
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Delaunay, Wylliam. "Synthèse et caractérisation de nouveaux matériaux organophosphorés pour des applications en optoélectronique." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00942602.
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Ce manuscrit décrit la synthèse et la caractérisation de nouvelles molécules incluant un cœur organophosphoré, le phosphole. Certaines de ces molécules ont été utilisées pour la fabrication de dispositifs OLEDs ou de cellules photovoltaïques organiques. Le premier chapitre fait un état de l'art de la chimie du phosphole dans le domaine des matériaux organiques entre 2010 et 2013. Le second chapitre décrit la synthèse et l'étude physico-chimique de molécules qui permettent de moduler l'angle de torsion dans les systèmes π conjugués pour faire varier les propriétés optiques et rédox. Une de ces molécules a permis la fabrication d'une diode blanche organique. Le troisième chapitre de ce manuscrit présente une structure tridimensionnelle intéressante, le 1,1-biphosphole. En plus de posséder une structure tridimensionnelle, ces structures présentent un mode de conjugaison original, la conjugaison σ-π, qui permet de réduire l'écart HO-BV de nos systèmes. Une de ces molécules a permis la fabrication de la première cellule photovoltaïque organique avec un dérivé du phosphole inséré dans la couche active. Dans une deuxième partie, ce chapitre traite également de la réactivité originale du 1,1'-biphosphole qui permet de fonctionnaliser l'atome de phosphore par une simple substitution nucléophile, permettant d'insérer une grande variété de substituants pour moduler les propriétés des molécules. Pour finir, ce manuscrit présente un quatrième chapitre qui implique le phosphole comme unité coordinante afin de réaliser des nouveaux complexes qui permettent de réaliser une ortho-métallation par activation C-H. De nouveaux complexes ortho-métallés d'Ir(III) et de Rh(III) ont été synthétisés et caractérisés.
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Lung-Chung, Lin, and 林榮鍾. "Photovoltaic property of the conducting polymer/n-type Si diode." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/35629498311036388704.
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碩士國立彰化師範大學
光電科技研究所
99
In this study, photovoltaic property of the conducting polymer/n-type Si (PEDOT:PSS/n-Si) diode was examined. In the dark, it is shown that the ultraviolet (UV) treatment may lead to an increase in the current density measured at positive voltage, owing to the reduction in the resistance of PEDOT:PSS. However, the current density measured at negative voltage for PEDOT:PSS/n-Si diode with UV treatment is similar to that for PEDOT:PSS/n-Si diode without UV treatment. In addition, it is found that the dominant conduction mechanism is the Schottky emission for PEDOT:PSS/n-Si diode. The difference between the barrier heights of PEDOT:PSS/n-Si diode with and without UV treatment is negligible. Under illumination (AM 1.5G,100 mW/cm2), the electrical characteristics of the PEDOT:PSS/n-Si diode with UV treatment show the short circuit current density (JSC) is higher than the PEDOT:PSS/n-Si diode without UV treatment. This is because of the reduction in the series resistance (RS) of the PEDOT:PSS/n-Si diode. RS does not affect VOC of the solar cell, this suggest UV treatment does not affect VOC of the device. Based on the result of capacitance–voltage measurements, we suggested that UV treatment may lead to a decreased number of charge-trapping-related defects, thus increasing conductivity of PEDOT:PSS. On the other hand, the reflectance of the diode with UV treatment is slightly lower than the diode without UV treatment indicated that UV treatment has more significant contribution to the increase in internal power conversion efficiency.
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Hsu, Chang-Jhih, and 許昶誌. "Admittance Simulation and Photovoltaic Effect of InAs Quantum Dots Schottky Diode." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/42561065800325514368.
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碩士國立交通大學
電子物理系所
104
In this study, we demonstrate an analytical expression for admittance of InAs/InGaAs dot-in-well layer embedded in a GaAs Schottky diode. There are two cases we need to consider: QD layer is located inside the depletion region and QD layer is located outside the depletion region. By solving the electrical field and potential energy of the depletion region and analyzing the carrier distribution in quantum confine states, we obtain capacitance and conductance as a function of both bias and frequency. We also discuss the capacitance measurement under illumination. Since QD layer serves as a capacitor under illumination, the photocurrent will charge QDs and cause photovoltaic effect. We find that the photocapacitance and an additional plateau in C-V measurement are all caused by photovoltaic effect. Furthermore, the time constant of photovoltaic effect is limited by the value of current. Thus we can observe the photovoltaic effect on C-V and I-V measurement by changing sweeping rate. Analytical expression for C-V measurement under illumination have been deduced and used to fit experimental data.
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Chiou, Sin-Rong, and 邱信融. "Effect of Light Emitting Diode Lumileds and Photovoltaic on Electric system in Taiwan." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/48263947964554304283.
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碩士國立成功大學
工程科學系專班
95
Melt globally and warmly day by day seriously, the climatic anomaly from all parts of the world takes place in succession , after Kyoto Protocol that the gas suppressing the global greenhouse effects on February 16 , 2005 discharges comes into force formally , energy technological innovation and social behavior of economizing the energy change and become the decrement effective tactics of carbon dioxide. Under the circumstances that Kyoto Protocol is limited and standardized , cooperate with the country to actively promote energy-conserving science and technology and energy industry in the future, this text proposes that Light Emitting Diode Lumileds and developed with the sun photoelectricity, and apply the photoelectric system of the sun to the house, the electric network of Taiwan is close and complete, cooperate with green scientific and technological industry Light Emitting Diode Lumileds and develop with photoelectric industry of the sun, adopt the grid-connected system in house solar energy and generate electricity , utilize solar energy to generate electricity on dispersing the roof of every building in the traditional large-scale power plant , and then give the application on the spot through losing and mixing telexes , improve the electric equilibrium of supply and demand of area, and prevent the land from seeking and accepting and polluting the question with the public hazards , reduce the power transmission and distribution cost, make the electric power system in the future of Taiwan can be developed continuously forever.
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Tseng, Wen-Chin, and 曾文欽. "Application of the Barrier Voltage Diode Model to Simulating Random Shading of Photovoltaic Modules." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/43333066671563220988.
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碩士國立雲林科技大學
電機工程系
102
Partial shading often happens to a photovoltaic (PV) power generation system and may greatly reduce its energy conversion efficiency. In this thesis, we build up the Barrier Voltage Equivalent Model (BVEM) according to the temperature characteristics of the Shockley diode model. In this thesis, the BVEM can simulate the instant variation of the solar irradiance and temperature of a PV module when the module is partially shaded. The measured solar irradiance and temperature data are used as the inputs of the BVEM for simulation and the results are compared with the measured power output data from the inverter to see the difference. The BVEM is tested for probabilistic simulation first for a single module, and then for two modules in series, without and with bypass diodes. Then we record the probability distribution of the maximum power output, and compare it with the result of simulation using Mathcad. Also, we use EMTP software to simulate three BVEM modules in series with and without bypass diodes with random solar irradiance. PV arrays of six connection configurations, including simple-series, parallel-linked, series-parallel, total-cross-tied, bridged-linked, and honeycomb, have been compared when exposed to random shading. The probability distribution of the array maximum power output have been observed.
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Chiang, Wang-Ta, and 江旺達. "High Efficiency White Organic Light-Emitting Diode in Stacked Photovoltaic Cell Device with Electron Multiplier." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/68557643343764377823.
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博士義守大學
電子工程學系博士班
98
This thesis includes three topics of carbon nanotube hole injection layer of organic light-emitting diode (OLED) and double-hole transport layer of organic solar cells (OPV) and organic light-emitting diode in stacked photovoltaic cell (PVOLED) as follows: In the first place of this thesis, we research an OLED with a nanocomposite layer of poly(3,4,-ethylene dioxythiphene):poly(styrene sulfonic acid) (PEDOT:PSS) doped with multi-walled carbon nanotube (MWCNT) as a hole injection layer (HIL). The structure of the OLED is glass/ITO/MWCNT-doped PEDOT:PSS/PEDOT:PSS/ tris(8-hydroxyquinolinato) aluminum (Alq3)/LiF/Al. The luminous efficiency of the OLED is as high as 2.1 cd/A, which is 70% higher than that of a conventional device without an MWCNTs-doped HIL. The MWCNTs in the PEDOT:PSS act as a hole-blocking material, that results retarded holes transport ability and the balance between electron and hole mobility, thus leading to enhanced luminescent performance. The mechanism was well demonstrated by through investigations by atomic force microscopy (AFM) of the HIL film surface morphology and carrier injection properties of hole-only devices. In the second part of this work, we investigated the high fill factor (F.F.) and high power conversion efficiency (PCE) of organic photovoltaic (OPV) cells using a dual hole-transporting layer (HTL) of vanadium oxide (V2O5)/copper phthalocyanine (CuPc) as a buffer layer. The OPV cell configuration consists of indium tin oxide (ITO)/V2O5/CuPc/poly(3-hexylthiophene) (P3HT):phenylC61-butyric acid methylester (PCBM)/LiF/Al. The F.F. and PCE of the device with a V2O5/CuPc dual buffer layer are approximately threefold and tenfold, respectively, greater than those of a conventional device (ITO/P3HT:PCBM/ LiF/Al) without the buffer layer. The F.F. and PCE of the device are 62.2 and 2.11%, respectively under a simulated AM 1.5G illumination of 100 mW/cm2. The increased PCE and F.F. of the device are obtained using a V2O5/CuPc buffer layer, which is attributed to the stepwise hole-transporting configuration and the both CuPc and P3HT:PCBM material of optical absorption are 600-800 nm and 300-600 nm, respectively, will be enhanced by means of matching active layers with complementary spectrum range. Finally, in order to enhance the efficiency and the contrast of OLED device, we present a novel PVOLED device, the WOLED and OPV will be combined into one PVOLED device, which it was connected by a transparent interconnecting layer of Al/MgO electron multiplier (dynode) has been realized. More significantly, this OPV is expected to act as an assisted carrier site for electron. It leads to the efficient recombination of electron-hole pairs in the emission region of OLEDs. The Al/MgO electron multiplier not only makes multiple electrons but also improves the emission uniformity and stability of the light-emitting device. The structure of the PVOLED is Glass/ITO/CuPc/m-MTDATA:V2O5/NPB /CBP: FIrpic: DCJTB/BPhen/LiF/Al/MgO/ P3HT:PCBM/V2O5/Al . At a given current density of 80 mA/cm2 exhibited luminance of 20635 cd/m2, a luminous efficiency of 4.7 cd/A and the contrast ratio of 9.3 were obtained at the device operated at 300 cd/m2 under an ambient illumination of 250 lux. In order to further enhance the contrast ratio in PVOLED, ITO front glass coated with MgF2/ZrO2/CeF3 multi-antireflective layer (ARC). Due to it can reduce ambient-light reflection from the device, that results it leads to the improvement in contrast ratio as high as of 9.8 and a white light emission with Commission Internationale De L’Eclairage (CIE) color coordinates of (0.32, 0.44) at 10 mA/cm2. The PVOLED device not only exhibits a contrast superior to the conventional OLED device but also can recycle energy transfer from both incident ambient illumination and internally generated WOLED emission to the device that results it can improves device efficiency. The proposed PVOLED is highly promising for use in outdoors display applications.
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Tsai, Fang-Yuan, and 蔡方元. "Spiro-Shaped cis-Stilbene/Fluorene Hybrid Template for the Fabrication of Small-Molecule Organic Photovoltaic and Organic Light-Emitting Diode." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8r4ehy.
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Cheng, Yu-Ching, and 鄭宇淨. "High voltage CMOS photovoltaic module with bypass diodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/zfb3k9.
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碩士國立中山大學
光電工程學系研究所
107
The open-circuit voltage of a silicon-based photovoltaic device (PV) is only 0.5V, which is not high enough to drive micro-electro-mechanical system (MEMS) devices. For example, driving an electrostatic actuator typically requires > 10V supply voltage and a low activation current (>1A). In this thesis we developed a 12.5-V high-voltage backside-illuminated CMOS PV mini-module by standard 0.18-m bulk complementary metal-oxide-semiconductor (CMOS) process. Serial connecting on-chip PV cells is achieved by localized substrate removal. To reduce the entire module cost, we also implement 10.5-V high-voltage PV modules using lower-cost 0.35-m bulk CMOS process, but the generated photocurrent is low due to the high electrical resistance of the substrate. Another issue in high-voltage PV module is its optical shading effect. Since the photocurrent generated by the PV cell is limited by the smallest current on any one of the PV cells in series, high-voltage PV module needs uniform illumination intensity profile. This issue is not critical for outdoor PV module using sun light as the energy source, however, the issue becomes series when the incident light is a laser beam with a Gaussian intensity distribution. A solution to this partial-shading issue is to employ bypass diodes in reverse paralleling with the PV cells. In this arrangement the bypass diode is block when all PV cells are illuminated, and conducts when one or several cells are shadowed. Here we employ heavily-doped junction diode to serve as the bypass diode. The initial results show photocurrent enhancement in partial-shaded PV module under laser illumination, but the turn-on voltage is not low enough to be driven by the PV cells. Our next step is to utilize CMOS Schottky diodes as the bypass diodes.
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Phlippen, Frank. "Einsatz schneller Halbleiterschalter in Wechselrichtern für die Photovoltaik /." 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014750287&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Tsai, Jung-lung, and 蔡忠龍. "Photovoltaic Cells and Light Emitting Diodes of Fully Conjugated Rigid-rod Polymer." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53802445368662280500.
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碩士國立中山大學
材料科學研究所
94
Polymer photovoltaic cell (PV cell) utilizes a polymer to absorb photons for generating excitons. When excitons are separated into electrons and holes, the device has the photovoltaic effect. Polymer light emitting diode (PLED) injects electrons and holes respectively from cathode and anode into a polymer emission layer. Some of the electrons and the holes would recombine to induce light emission. This research used a heterocyclic aromatic rigid-rod polymer poly-p-phenylene- benzobisoxazole (PBO) as the opto-electronic layer, and a conducting material of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) as the hole transport layer. PV cells were fabricated using indium-tin-oxide (ITO) as anode and aluminium as cathode. Same layer arrangement was applied for PLEDs. These two kinds of devices were measured for electrical and optical response. It was evidenced that the addition of PEDOT:PSS layer facilitated the separation of excitons into electrons and holes at the PBO/PEDOT:PSS interface. Insertion of a LiF layer between PBO layer and Al cathode reduced their energy band gap and facilitated charge transport leading to an enhanced efficiency for PV cells and PLEDs. Thickness variations were found on spun PBO layer. According to emission intensity, we knew that the PBO layer quality was significant for electroluminescence. Introduction of a PEDOT:PSS layer improved the interface between ITO and PBO. The thickness of PEDOT:PSS layer depended on the ITO surface roughness. With a PEDOT:PSS layer, the opto-electronic efficiency of PV cell and PLED was improved.
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廖椿毅. "Design and Synthesis of Organic Optoelectronic Materials for Organic Light Emitting Diode and Organic Photovoltaics." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/82523841547828173892.
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Hsu, Wei-En, and 徐偉恩. "Efficiency Improvement of Photovoltaic integrated Organic Light Emitting Diodes by Applying Optical Filters." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/25921500351695289345.
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碩士國立臺灣大學
電機工程學研究所
100
Organic light emitting diode (OLED) is becoming a major technique for display technology due to many properties such as self-emissive, fast response time and flexible application. However, poor outdoor contrast ratio of OLED is an important issue to be discussed. Therefore, many efforts were devoted into related researches, such as integrating polarizer and reflective liquid crystal with OLED. Recently, due to the promotion of environmental protection consciousness, an energy-recycling device—thin-film solar cell integrated OLED, would become an attractive solution to contrast ratio problem among many other solutions. Although the integrated device of OLED and solar cell would provide contrast ratio enhancement and energy recycling ability, it would also decrease the luminous efficiency to about 50% as compared to the original OLED. This would become an obstacle to develop this eco-friendly technology. In this thesis, we focus on designing optical filters with a desired spectrum. By enhancing the OLED emission reflection, and suppress other band besides OLED emissive band, the filters would enhance the OLED emission while keep high contrast ratio. This thesis starts from verifying formal research and building optical simulation models, followed by proving assumptions and designing optical filters. In the last part, we made some analysis and discussions about the effect of filters. By considering optical filters, we discussed two common optical structures, i.e., the distributed Bragg reflector (DBR) and guided mode resonance (GMR) filter. We use analytical solution to obtain ideal reflectivity and suitable bandwidth. For the GMR part, we scan different parameters by using the relationship of parameters and reflection spectrum to obtain an ideal spectrum with a simple structure. Finally, we compare the two optical filters and discuss the possibility of full color display realization. Moreover, we discuss the possibility of applying the filters for reflective display devices.
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Kozłowski, Fryderyk [Verfasser]. "Numerical simulation and optimisation of organic light emitting diodes and photovoltaic cells / von Fryderyk Kozlowski." 2005. http://d-nb.info/978267524/34.
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Shen, Chia-Yu, and 沈家宇. "Luminous-efficiency Improvement of Photovoltaic-device-integrated Organic-light-emitting Diodes with Subwavelength Metallic Gratings." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/14526775690598986990.
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碩士國立臺灣大學
光電工程學研究所
101
OLEDs have been reported being integrated with photovoltaic devices as tandem structures. In this way, the tandem structure of the devices can absorb and induce destructive interference of the incident light due to the integrated solar cell that can reduce the ambient light reflection and achieve the improvement of the contrast ratio of OLEDs. In addition, the ambient light can be recycled into energy at the same time. However, this device reveals one problem, namely that the total brightness of OLEDs is decreased by integrated solar cells. In order to solve this problem, previous research designed a distributed Bragg reflector(DBR) and tow-dimensional guided-mode-resonance filters (GMRFs) between OLEDs and solar cells to enhance brightness and maintain the contrast ratio of the OLEDs. In the same vein of previous research, we design one-dimensional dual-function subwavelength metallic gratings to replace the independent DBR and tow-dimensional GMRFs structure. One-dimensional dual-function subwavelength metallic gratings are modified as wavelength selective optical filters in the tandem structure device, which in turn reflect more specific interval of the OLED spectrum and increase the luminous efficiency. In addition, they also can be wavelength selective optical filters which reflect red, green, or blue light depending on the different periods and widths of gratings. By designing the gratings and choosing the thickness of dielectric layer, we successfully improve the luminous efficiency and contrast ratio of conventional PVOLED.