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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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Study of perovskite solar cells degradation
Hrbková, Silvie ; Novák, Vítězslav (referee) ; Vala, Martin (advisor)
This thesis studies the degradation of perovskite photovoltaic cells placed in atmospheres of different moisture. Samples with inverse structure: ITO/ PEDOT:PSS/ CH3NH3PbI3–XClX / PC70BM/ Ca/ Al were prepared. Electrical characteristics were measured for 2 months and similar degradation trend was observed for all the samples. Perovskite cell efficiency PCE decreased to 20 % of the initial value in t80= 46±3 days in laboratory, t80=23±1$ days in nitrogen atmosphere and t80=25,7±0,6 dní days in dry atmosphere. For the initial 27 days of the experiment, a faster degradation linked with the decrease of ISC, FF and VOC was observed. After this period, the value of FF has stabilised at 0,777±0,009 % and the value of VOC at 0,70±0,02 % of their original value (in the laboratory atmosphere). Additional fall of PCE resulted only from the decrease of ISC and was slower than in the initial period. From the results acquired, it has emerged that during the experiment, the cell encapsulation provided a sufficient barrier against outer moisture. Residual moisture present in the sctructure, was labeled as the source of the degradation. The moisture is believed to enter with the hygroscopic material PEDOT:PSS during the samples preparation procedure. During the degradation, absorption measurements of photovoltaic cells were executed. The absorption spectra didn't change. That indicates, that the decrease of ISC is not caused by the reduction of light absorption. The thesis also studied the degradation of perovskite solar cells under illumination. The samples were exposed to UV radiation for 55,5 hours. The PCE time of decrease to 20 % of the initial value was t80 = 6±2 days. It was revealed, that UV radiation significantly accelerates the decrease of ISC.
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Highly porous ceramic oxide materials for environmental catalysis
Husťák, Miroslav ; Částková, Klára (referee) ; Cihlář, Jaroslav (advisor)
As far as the replacement of fossil fuels with more environmentally friendly options is concerned, hydrogen is considered as the most promising source of energy. Currently, hydrogen is mainly produced through the method of methane reforming. This method requires the utilisation of catalysts made of precious metals. This master's degree thesis therefore investigates perovskite materials SmCoO3, Sm0,8Ca0,2CoO2,9, SmCo0,8Al0,2O3 and Sm0,8Ca0,2Co0,8Al0,2O2,9, which could be utilised as catalysts in the production of hydrogen by methane reforming. Methane reformation occurs on the surface of a catalyst. Therefore, it is desirable to ensure that the specific surface area of a catalyst material is as large as possible. For that reason, the aforementioned perovskite materials were prepared by two sol-gel methods, which are expected to create perovskites with large specific surface areas. It was investigated in the course of the work how the method of synthesis affects the structure and catalytic properties of individual materials. The SmCo0,8Al0,2O3 material prepared by a sol-gel synthesis with propylene oxide as a gelation agent demonstrated the best results - the measurement of catalytic activity showed that the methane conversion had achieved the value of 99%.
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