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Microscopic analysis of silicon solar cells defects
Brukner, Jakub ; Solčanský, Marek (referee) ; Stojan, Radek (advisor)
This thesis deals with detection of defects solar cells using method electroluminescent, electron microscope and subsequent 3D modeling of areas with defects and structure of the solar cell. In the text are describe basic methods for detection of defects appearing in solar cells. Also some basic defects which can be made during manufacture are there describe. For better orientation the basic principle of functionality and manufacturing process is included.
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Material prinitng of electroluminiscent panel
Guricová, Patrícia ; Dzik, Petr (referee) ; Vala, Martin (advisor)
This works deals with the preparation of luminescent lamp using screen printing method, characterization of individual layers and the study of spectral properties, influenced by changing printing parameters. In theoretical part are described the principles of electroluminescence as well as the method of preparation of the luminiscent lamp. Experimental part involves optimazing of printing parametres, so the homogenneous light emission is achieved. Furthermore, the influence of the change in the number of layers of active material and dielectric on the light output of the panel at the lowest working voltage is studied. The result of this work is a funcional electroluminescence lamp and an optimazed process for its preparation.
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Study of optoelectrical properties of organic semiconductor thin film layers
Kovář, Jakub ; Weiter, Martin (referee) ; Zmeškal, Oldřich (advisor)
This thesis concerns with electrical and optoelectical properties of thin organic semiconductor layers. In the research, organic electroluminescent devices were prepared and the effect of illumination and inclusion of organic interlayers, that act as alternative electrodes, on charge injection and transport were investigated on them by means of electrical measurement and impedance spectroscopy. On the basis of measured data, the thesis attempts to determine materials best suited for interlayers, which could make an improvement of electric properties of electroluminescent devices possible. The sence of using a combination of direct current measurement and impedance spectroscopy was also discussed in the thesis.
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Study of the influence of the dielectrics on the optoelectronic properties of electroluminescent devices
Foldynová, Klára ; Novák, Vítězslav (referee) ; Vala, Martin (advisor)
This diploma thesis is studing the possibilities of influencing the optoelectric properties of printed light emitting panels, which work on the principle of electroluminescence excited by alternating electric field. The aim of this worrk is to monitor the influence od dielectric properties of electroluminescent phosphor binder on the targeted electroluminescence. In the theoretical part of this thesis, there are described principles of electroluminescence, suitable materials methods of characterization and preparation of panels using printing techniques. Experiment part contains electrical characterization of selected binders to determine their dielectric constants. Subsequently, printing pastes were formulated in different weight ratios of binder electroluminescent phosphor and model light-emitting panels were prepared. Optoelectric characterization was used to determine the change in irradiance. It was found that the dielectric properties of the binder significantly affect the resulting irradinace. It has same irradiance for a smaller amount od phosphor than with the binder with a low dielectric constant. The finding of this work can be used to improve the luminosity at the electroluminescent panels.
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Modification of inks for luminescent panels
Foldynová, Klára ; Dzik, Petr (referee) ; Vala, Martin (advisor)
This bachelor thesis deals with the study of the influence of luminescent additives on the features of printed electroluminescent elements. The goal of the thesis is to find a strategy for expanding the color spectrum of these elements while maintaining their functionality. An important step was the addition of additive to the basic luminescent layer of ZnS and its influence on emission of radiation. A change of color spectrum was proved by usage the U111 fluorophore and in particular the wavelength change and the intensity of the radiation on the input voltage and frequency were observed. The obtained results can be used in further studies to extend the knowledge of electroluminescence.
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Photoluminescence diagnostic method with transmission illumination
Kafka, Martin ; Veselý, Aleš (referee) ; Vaněk, Jiří (advisor)
The aim of this diploma thesis is an innovation of photoluminescence measure research workplace for measurement of cells structure defects by method of transmissive illumination while employing the current methods of measurement of defect in the solar cells structure. The first part deals with explanation of historical development of solar energy, of how we can reach production of electric power with contribution of solar radiation and defines usability of solar cells in practice. The thesis further analyses a practical application of measurement via laboratory diagnostic methods used by Department of Electrotechnology Brno University of Technology. The second part is focused on mechanical design of experimental photoluminescence measure workspace used for quick diagnostic defects employing the rear arousing source for detection of defects with assistance of transmissive system of illumination. Finally, with co-operation of SOLARTEC s.r.o. three types of solar cells are measured by this new method and compared with results of measurement via diagnostic methods of LBIV (Light Beam Induced Current), LBIC (Light Beam Induced Voltage), Electroluminescence, Photoluminescence, and detection defects by radiation of Microplasma.
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Operating Characteristics of LED Sources
Brdečko, Aleš ; Diviš, Daniel (referee) ; Baxant, Petr (advisor)
This semester thesis is dealing with issues of LED (light emiting diod).In the text we can find general summary knowledges about LED, relating their history, construction, principle of working and also treatise about of semiconductor compounds. In thesis are given examples of use indicating their advantages and disadvantages and indicating their parameters. The practical content of this thesis is evaluation of measurement performed on some samples of LED especially graphics addiction of crosses and V-A characteristics measured in addiction on current.
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Solar cells photoluminescence defect detection methods
Vala, Zbyněk ; Veselý, Aleš (referee) ; Vaněk, Jiří (advisor)
This thesis discusses modern methods for fast defect detection of solar cells. For the means of the defect classification, the technological production process of crystalline silicon solar cells is described. The defects are researched by the electroluminescence and prohtoluminescence methods. The Photoluminiscence method is improved by the posibility of using different wavelenght of excitacion sources. The range of using in industrial production is determined for the discussed methods.
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Electronic ballast for power LEDs
Vágner, Richard ; Martiš, Jan (referee) ; Červinka, Dalibor (advisor)
This diploma thesis deals with design of power LED driver. This driver contains electronic ballast circuits, converters, filters and control circuits. Overviews of circuits used in practice are listed along with analysis of power LED and considering options for selecting an appropriate design solution. Thesis describe principle of electroluminescense, creating of the device, its structure and problematics of current source supply. Including detailed overview of converters, ballasts and topologies used in lighting systems with the selection of a suitable solution for the final device with an output power of 50 W. The thesis contains cooling dimensioning for selected power LEDs, input circuit with EMI filter, bridge rectifier, boost converter and flyback converter with pulse transformer.
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Electronic ballast for power LEDs
Vágner, Richard ; Martiš, Jan (referee) ; Červinka, Dalibor (advisor)
This diploma thesis deals with design of power LED driver. This driver contains electronic ballast circuits, converters, filters and control circuits. Overviews of circuits used in practice are listed along with analysis of power LED and considering options for selecting an appropriate design solution. Principles of creating the device, structure and problems of current source are described in thesis. Including detailed overview of converters, ballasts and topologies used in lighting systems with the selection of a suitable solution for the final device with an output power of 50 W. The thesis includes cooling dimensioning for selected power LEDs, input circuit with EMI filter, bridge rectifier, boost converter and flyback converter with pulse transformer.
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