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Optical characterization of perovskite nanostructures
Urban, Jakub ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
The present bachelor's thesis focuses on the optical characterization of CsPbBr3 nanocrystals ranking among the group of materials called perovskites which are remarkable for their high photoluminescence (PL) quantum yield. An algorithm for a correlation of experimental data measured by PL mapping with morphological and topological properties obtained by using Scanning Electron Microscopy and Atomic Force Microscopy has been developed which clears the way for a particular crystal detection and their spectrum analysis. Specifically, crystals the shape of which can be approximated by a cuboid have been detected and the volume dependence of the centre of mass of their PL, which is proportional to V^(-2/3) as predicted by the theorethical model, has been discovered. The measurement of PL dependency on temperatures ranging from 40 to 60 °C has also been conducted and in this temperature interval linear dependence of the full width at half maximum of their PL spectral line that rises with rising temperature has been confirmed. On the contrary, the centre of mass of PL has been found to be temperature independent.
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Synthesis of functional ceramic powder materials
Čípová, Eva ; Maca, Karel (referee) ; Částková, Klára (advisor)
The theme of the work is electroceramic materials, particularly materials based on perovskites. The theoretical part describes electroceramic materials, their applications and possibilities of their synthesis. The experimental part focuses on the synthesis methods in liquid media and solid phase of barium strontium titanate. The prepared powders were characterized by morphology, phase composition and particle sinterability. It was found that weakly agglomerated particles with a single phase composition, perspective for the preparation of dense bulk ceramics, were prepared by the metod in liquid phase, especially by precipitation.
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Charakterizace vlastností perovskitovských fotovoltaických článků
Salaukou, Aleh ; Vanýsek, Petr (referee) ; Novák, Vítězslav (advisor)
This work deals with photovoltaic cells based on perovskite. The theoretical part describes the basic properties of perovskite structure, its composition and its using in solar cells. In addition, the work provides basic information about photovoltaic and silicon solar panels. Information on photovoltaic cell measurement methods such as impedance spectroscopy, photoimpedance spectroscopy, and load curve method are also presented here. Practical part of the Bachelor work deals with the application of measuring methods described in the theoretical part, the determination of equivalent circuits and discussions about the results obtained.
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Impedance spectroscopy characterization of perovskite solar cell materials
Křečková, Jitka ; Vanýsek, Petr (referee) ; Novák, Vítězslav (advisor)
The Master‘s thesis deals with the topic of perovskite solar cells with the main focus on the materials used for the active layer. In the introductory part, the electrical and optical properties of halide perovskites are described and specific examples of perovskite crystals are introduced. The description of impedance and photoimpedance measurement methods used for characterization of perovskite solar cells is also included in the thesis. The measurement of electrochemical impedance spectroscopy was conducted on four perovskite crystals and equivalent circuit was formed to fit the obtained data. Parameters of the circuit elements were acquired using the fitting method and were further evaluated in experimental part of this thesis.
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Practical applications of superconductivity
Mádrová, Tereza ; Langerová, Petra (referee) ; Baumgartnerová, Alena (advisor)
Předložená bakalářská práce je zaměřena na zpracování souhrnného přehledu využití supravodivosti v technických řešeních a aplikacích, čímž se rozumí nikoliv experimentální využití, nýbrž využití v reálném technickém řešení. Tato práce se věnuje zejména popisu, v první části základním atributům supravodivosti, bez nichž není možné princip supravodivosti pochopit a jsou tudíž nezbytnou součástí práce, ve druhé části rozdělení do kategorií supravodičů podle určitých kritérií, a v poslední části popisuje příklady aplikací supravodivosti tak, jak se s nimi můžeme setkat v každodenním životě.
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Perovskite solar cells
Poláková, Simona ; Zmeškal, Oldřich (referee) ; Pospíšil, Jan (advisor)
The bachelor´s thesis deals with the study of perovskite solar cells. The theoretical part of this work is devoted to the stability of the perovskite layer and perovskite solar cells, especially chemical and thermal stability are discussed. Furthermore, deposition methods of perovskite active layer were described in more detail. The experimental part deals with the influence of the dropping of the diethyl ether solution during the deposition of the active layer (at different time intervals) on the final efficiency of solar energy conversion, with the preparation of the final perovskite solar cells and with the characterization of the basic electrical properties of the prepared structures.
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Perovskite-based optical sensor
Frkáň, Lukáš ; Jandová, Kristýna (referee) ; Novák, Vítězslav (advisor)
The aim of this Master´s thesis is to frame the concept of perovskite-based materials, provide basic information about perovskite-based materials and scrutinize their potential in terms of optical sensors manufacturing. The thesis also deals with monitoring of the sample in terms of long-term stability. The analysis of measured characteristics and their properties is included in this semester thesis as well, along with the methodology of testing and evaluating of the results.
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Development and Innovation of Manufacturing Processes for Thin-Film Solar Cell Functional Layers
Kadlec, Michal ; Vanýsek, Petr (referee) ; Tauš, Peter (referee) ; Vaněk, Jiří (advisor)
The doctoral thesis deals with a group of thin-film photovoltaic cells based on pigment or perovskite absorption layers of light energy. The principal functionality of the cell is based on the capture of light by the pigment on a photosensitized semiconductor anode with subsequent regeneration of the pigment by the electrolyte. In our research we focused on the preparation and optimization of perovskite solar structures based on TiO2/CH3NH3PbI3. A total of six series of experimental solar cells with a perovskite structure were produced. The first two series were realized according to the chemical formula CH3NH3PbI3. In the other series, we applied the theory of added chlorine, resulting in the chemical formula CH3NH3PbI3Cl2. We defined the requirements for the creation of an active perovskite structure in the cell and determined its photovoltaic properties depending on the composition.
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Perovskite materials
Gavranović, Stevan ; Zmeškal, Oldřich (referee) ; Pospíšil, Jan (advisor)
This bachelor´s thesis is focused on a study of electrical properties of perovskite single crystals prepared by inverse temperature crystallization (ITC). Measurements were done on the organic-inorganic halide perovskite monocrystal MAPbBr3 and on the completely inorganic halide perovskite monocrystal CsPbBr3. Crystalline structure and chemical composition of prepared single crystals were determined using x-ray diffraction analysis. Current-voltage characteristics of perovskite monocrystals were measured using solar simulator. Hole carrier mobility were calculated from determined current-voltage characteristics using SCLC method. Furthermore, the dependencies of dielectric permittivity on frequency of alternating current were measured. MAPbBr3 single crystal showed better electrical properties (higher hole carrier mobilities) than CsPbBr3.
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Rheological properties of gels for Pechini syntheses
Wirthová, Michaela ; Ptáček, Petr (referee) ; Zmrzlý, Martin (advisor)
This work deals with preparation of layers of ceramic materials – perovskites. The introductory part includes general characteristics concerning structure, properties and use of this materials. In details then there is described method of their preparation, namely Pechini´s syntheses, which are most widely used. Optimum molar ratio of components is discussed, in the sense of what compositions lead to creation of perovskite structures. Influence of this parameter on rheological properties of precursory gels is described in the end of the first part of work. In experimental section there are described preparations of gels, which are prepared via reaction between citric acid and ethylene glycol and gels, which are prepared by Pechini´s synthesis. Rheological properties of prepared gels (density, viscosity and surface tension) and besides determination of amount of nitrates in gels are characterized. Temperature dependence of viscosity of gels, that are prepared by reaction of citric acid and ethylene glycol are determined. In final part successful preparations of perovskite layers is shown on ceramic substrate. This layers are observed by means of light optical microscope and scanning electron microscope.
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