National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Inovation of measurement equipment used for analyzing of photovoltaick cells
Otépka, Jakub ; Bača, Petr (referee) ; Vaněk, Jiří (advisor)
This bachelor thesis deals with the design of a tachometer which is used to measure and display of mechanical aperture speed of a measuring equipment for the defect analysis of solar cells using the photoluminescence method. This work is divided into three parts. The first section describes the principle of solar cells, the principle of luminescence radiation and its types. Next the defects of solar cells are analyzed. The second part discusses the theory of tachometers, the principles and methods of loading pulses. The third part is then analyzed the design and construction of the selected type tachometer.
Luminescence Diagnostic of Photovoltaic Cells
Stojan, Radek ; Frantík, Ondřej (referee) ; Šály,, Vladimír (referee) ; Vaněk, Jiří (advisor)
Diagnostic of photovoltaic cells defects is one of the key step in production. This dissertation thesis deals about diagnosis of photovoltaic cells by radiative recombination of electron - hole pairs. This radiative recombination is known as luminescence. Diagnostic methods using this local light emission in infrared region have innovative potential. The method of electroluminescence is one of the most widely used luminescence methods whose modifications are applied across the industry, especially in semiconductors. The main area of this thesis research is focused on non-destructive analysis of radiated infrared radiation of monocrystalline and polycrystalline solar cells in various modifications of standard electroluminescence method. In this research there are used two types of CCD cameras are used as luminescent radiation detectors. Method of photon emission microscopy is used for magnification element. Local light emission inspection by microscopy should have benefit to qualitative evaluation of solar cells defects. Radiation emitted by the solar cell has a wave character. This fact brings the potential of using some of the characteristics of the waves. We are talking about the intensity and mainly about new characterization by polarization during the detection of defects in the solar cell surface. Innovation of the measuring workplace of the standard electroluminescence method to use polarization analysis is one of the goals of this dissertation thesis.
Measurement of spectral characteristics in Labview environment
Konečný, Dávid ; Hégr, Ondřej (referee) ; Boušek, Jaroslav (advisor)
This work deals with design of a program for measurement of characteristics luminescence of inorganic semiconductors in LabView environment. After understanding with theoretic part a program for automated measurements was made including two type of measurements option. The program for measurement of Volt-Ampere characteristics by given wave length and for measurement of current on wave length dependencies is presented.
System for electroluminiscence defect detection of solar cells
Marčík, Silvestr ; Jandová, Kristýna (referee) ; Vaněk, Jiří (advisor)
The master thesis focuses primarily on issues of photovoltaic cells in terms of their defects. The introductory part deals with the history of photovoltaics, their introduction into practice and finally an explanation of the photoelectric effect itself. The thesis also describes photovoltaic cells themselves. It explains their principle, advantages, disadvantages and the creation of photovoltaic systems. A substantial part of the work is focused on the topic of detection of defects using luminescent methods. Subsequently, it describes procedural defects arising from the improper handling of already manufactured products. The final part deals with the main topic of the work, which is a detection using luminescence methods and it also mentions the non-luminescence method LBIC. The practical part of the master thesis contains the analysis of the current solution and of the subsequent proposal of solution using a low cost camera. It describes how to modify the camera, verify its spectral sensitivity using a spectrometer and measure the sensitivity of the CMOS sensor. The conclusion is focused on verifying the functionality of the proposed solution on different sources of infrared radiation and photovoltaic panels themselves.
Smart materials
Valenová, Ludmila ; Němec, Karel (referee) ; Molliková, Eva (advisor)
The bachelor thesis deals with smart materials. In summary, it describes the general classification of smart materials into individual groups. Describing the properties of individual groups and using these materials in practice. In more detail, there are described groups of shape memory materials, color changing materials under the external stimulus, light emitting materials and materials based on piezoelectric effect.
Preparation of graphene quantum dots and study of their properties
Zdražil, Lukáš ; Mikula, Milan (referee) ; Zmeškal, Oldřich (advisor)
Current methods for preparing graphene quantum dots (GQDs) rely on oxidation and reducing agents or require energy-intensive and technologically demanding preconditions. Applying microwave expansion and liquid phase exfoliation (LPE) in a sample of graphite powder enabled us to prepare GQDs that exhibit strong luminescence in the blue region of the visible spectrum. The proposed technique for synthesizing GQDs is energetically undemanding and does not necessitate additional chemical components.
Use of nanomaterials to improve optical detection of biomolecules
Špačková, Simona ; Kristýna, Pavelicová (referee) ; Bezděková, Jaroslava (advisor)
The bachelor thesis deals with modern methods of biomolecule labeling. Attention is paid especially to luminescent labeling with semiconductor quantum dots, optimization of preparation and characterization of quantum dots (QDs) and their bioconjugates with Ala4 peptide, which has antibacterial properties. The first method of preparing QDs used UV-radiation and conjugation with the peptide of interest was carried out through the thiol group of the peptide. A second type of QDs was prepared thermally and conjugation with the peptide was performed by linkers EDC/sulfo-NHS, which allowed peptide bond formation between the carboxyl group of QDs and the amino group of the peptide. The next part of the thesis is focused on the influence of conjugation the antimicrobial activity of the peptide. To verify the antimicrobial properties of the peptide, an interaction between the QDs-Ala4 conjugate and Staphylococcus aureus was observed. Conjugates thus prepared were characterized by fluorescence spectroscopy and capillary electrophoresis with absorption detection (-214 nm).
Automatization of an optical setup for time-resolved spectroscopy
Šimek, Daniel ; Klenovský, Petr (referee) ; Dvořák, Petr (advisor)
Time-resolved spectroscopy is a modern method enabling the analysis of the dynamics of quantum luminescence transitions. This method uses ultra-fast light pulses to study materials, which makes it possible to observe the time evolution of luminescence quenching and thus provides additional information for static absorption and emission spectroscopy. This diploma thesis deals with the automation of the optical setup used in the Optical and Plasmonic Laboratory at Ceitec Nano for performing time-resolved spectroscopy. As part of the work, an application was created enabling communication with 13 devices used in the laboratory. The application automates already performed measurements, and in addition enables the scanning of samples, which was not possible due to time constraints due to the manual control of the stage movement. At the end of the work, test measurements are performed, with a discussion of their effectiveness and time savings for the user.
Noncontact temperature measurements using luminescent materials
Jedlička, Jindřich ; Nebojsa, Alois (referee) ; Ligmajer, Filip (advisor)
This diploma thesis deals with noncontact temperature measurement using luminescent materials. In the theoretical part of the thesis, luminescent materials were selected on the basis of a literature review with respect to sensitivity and operating temperature range. In the experimental part of the thesis, photoluminescence of CdSe/ZnS and GaAs quantum dots for various temperatures was measured and the relative change of luminescence parameters such as emission peak position, intensity, intensity ratio of two emission peaks, and lifetime of luminescence were determined from the measurements in agreement with expectations according to the literature. Achieving high spatial resolution would be made possible by measuring cathodoluminescence, where the luminescence spectra are obtained with an order of magnitude higher spatial resolution. These measurements and the influence of electron beam on the luminescence quality of selected materials will be subject of further experimental study.
Transformation of ZnO-based structures under heavy Mo doping: Defect states and luminescence
Buryi, Maksym ; Remeš, Zdeněk ; Děcká, Kateřina ; Mičová, J. ; Landová, Lucie
Hydrothermally grown ZnO-based structures were heavily doped with Mo (various doping levels from 2 to 25%). It has been found that Mo strongly affects the ZnO structure and morphology rather resulting in the complex, mixed zinc and molybdenum oxides creation. Moreover, the material phases transformation upon the increased Mo content was observed. ZnO material phase was observed only at low Mo doping level (2 and 5%). This correlated very well to the changes in the luminescence and electron paramagnetic resonance signals.

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