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Study of electrical and dielectric properties of perovskites
Moravčík, Marek ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This bachelor’s thesis is focused on a study of electrical and dielectrically properties of perovskite single crystal prepared by inversed temperature crystallization. Measurement was done on sample of MAPbBr3. First the temperature dependences of current-voltage characteristics were measured, they help to determined Arrhenius dependences. Activation energies were determined from Arrhenius dependences for every single voltage. These activation energies were used to determined position of Fermi level during thermodynamic balance. Concentration of state for dominant energies and charge carrier mobility (drift, microscopic) were determined from current-voltage characteristics for constant temperature. Relative permittivity was used to determine these parameters from impedance measurement.
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Organic solar cells prepared by methods compatible with printing technologies
Babincová, Kristina ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
The theoretical part deals mainly with basic properties of organic materials, which are used in electronics, and especially in the field of photovoltaic cells. The experimental part deals with preparation of photovoltaic cells by deposition from solution, characterization of their basic electrical properties and preparation of a photovoltaic cell with its own pattern. Samples of classical and inverted structures of photovoltaic cells with P3HT and PCBM bulk heterojunction were prepared. Reference samples were prepared under standard conditions (under nitrogen). Their efficiency was around 3 %. In addition, samples were prepared by spin coating under laboratory conditions and by spreading. In both cases, their efficiency was about 1.5 %. Large-scale photovoltaic cells (active area of about 1 cm^2) were prepared in the last experiment presented. Efficiency decreased to 0.75 %. From results mentioned above is clear that very simple methods and procedures that do not impair the price/performance ratio can be used to prepare photovoltaic cells.
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Geoturistický potenciál vybraných geologických a geomorfologických lokalit v okolí Milov ve Žďárských vrších
Pospíšil, Jan
The interest of this bachelor thesis is the evaluation of the geotourism potential of seven selected geological and geomorphological localities around Milovy in the Žďárské hills, their very characteristics and evaluation using the already established methodology of geosites / geomorphosites Mrs. RNDr. Lucie Kubalíkové, Ph.D. Selected localities represent not only natural monuments or nature reserves in the form of rock formations, which are in terms of geotourism within the area of interest very attractive, but also neglected meanders of the Svratka River. Geotourism potential is evaluated on the basis of methodological evaluation and questionnaire survey, designed for the target group of respondents. The key participants of the questionnaire survey are local residents (stakeholders) and visitors (tourists). The thesis compares the view of local residents and tourists on geotourism itself in the given locality and informs about the possible positive and negative impacts of tourism within the area of interest with an emphasis on selected geological and geomorphological sites.
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Device that presents the vulnerabilities of the Internet of Things
Navrátil, Václav ; Pospíšil, Jan (referee) ; Martinásek, Zdeněk (advisor)
This bachelor thesis focuses on creating checklists that will be used to perform security penetration testing of IoT devices. The theoretical part discusses the principle of IoT, the most commonly used communication protocols, the ISVS security standard and the resulting checklist. The next chapter, i.e., the practical part, contains procedures describing the manual testing of several IoT products. IoT devices were purchased for this purpose as a single unit along with the tools to test them. In total, four comprehensive tests were performed in the practical part.
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Study of optical properties of perovskites and their precursors thin films
Blahut, Jan ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
The thesis is focused on the study of the optical properties of thin films of perovskites and their precursors. The first two chapters of the theoretical part are theoretical introduction to the studied problems, they discuss the basics of electromagnetic radiation and its interaction with matter and basic informations about perovskite materials, especially their semiconductor structure. The remaining two chapters deal with specific principles and practical uses of methods and procedures for the preparation of thin films, as well as the instrumentál characteristics of thin films in terms of their optical properties. The experimental part is focused on the preparation of solutions of perovskites and their precursors, where the replication and optimization of published procedures took place, the preparation of thin layers of these solutions by the spin coating method and their ellipsometric characterization using the Tauc plot method, modeling and fitting of the experimentally determined data, which led to the determination of the index refraction, absorption coefficient and band gap width of individual materials.
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Koncepce pohonů osobních automobilů
Pospíšil, Jan
This work is focused on the conception of the drives cars. You will become acquainted with the various concepts pioneered in the field of passenger cars, with the advantages and disadvantages of each approach and the current situation. Further mention of the development of concepts for passenger cars and where it will go in the future. In addition, there will be described and technical solutions specific vehicle. First of all, familiarize yourself with the concepts that are 4, but each is unique. In the historical part I will focus on the pioneers and interestingly designed cars. Development of the concept of drives already a few years point to the use of alternative fuels and hybrid technology.
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Computer-Controlled Planting
Pospíšil, Jan ; Šimek, Václav (referee) ; Růžička, Richard (advisor)
This work is focused on the issue of plant cultivation in domestic conditions. We focused on the automation of the growbox using the Wemos D1 R32 ESP32 board, which then consists of the design and implementation of three parts of the solution, i.e. the growbox itself, including the sensors needed to maintain ideal conditions for the plant being grown, the user applications, for interpreting the values and the configuration of the growbox. Application to collect data from growbox, for later analysis. The solution includes the creation of a demonstration growbox, software for all parts and comparison with available home growing systems.
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On Market Efficiency, Optimal Distributional Trading Gain, and Utility Maximization
Navrátil, Robert ; Večeř, Jan (advisor) ; Witzany, Jiří (referee) ; Pospíšil, Jan (referee)
On Market Efficiency, Optimal Distributional Trading Gain, and Utility Maximization Robert Navr'atil The aim of this thesis is multifold. First, using results from the optimal distributional trading gain problem, we determine a utility-maximizing portfolio that optimizes the benefit an agent may receive by trading the difference between his perceived future distribution of a security price and the risk-neutral density provided by the corresponding option market. Moreover, we show how one can fit the risk-neutral density directly from option market data using the SVI parameterization. We use integer programming with kernel search heuristics to statically replicate the optimal payoff. Second, we show that the United States equity market was inefficient during the weeks following the initiation of the COVID-19 pandemic. This is demonstrated by showing that utility-maximizing agents over the period ranging from mid-February to late March 2020 could generate statistically significant profits by utilizing historical price and virus- related data to forecast future equity ETF returns. Finally, we focus on the passport option. We present a version of insurance of a traded account that symmetrically treats both of its underlying assets. In our approach, we impose a natural symmetric limit in which the agent can...
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Study of electric properties of thin films of perovskite precursors
Harna, Václav ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
High efficiency perovskite solar cells may be the solution to obtain cheap renewable solar energy. However, characteristics of crystalline perovskite materials suitable for solar cells are not yet all clearly understood. In this thesis was studied and optimized the preparation of perovskite methylammonium lead tribromide (MAPbBr3) crystals using anti solvent vapor assisted crystallization (AVC). These crystals were prepared and studied in a small channel between two carbon electrodes on 3D printed substrate made from polylactic acid (PLA) connected to a larger electrode system were measuring took place. Electrical properties of prepared crystal structures were studied using current voltage characteristic and the process of crystallization was documented. Crystal prepared by AVC method achieved sizes larger than 0,5 mm, their electrical conductance increased with their size and the crystals were photo and thermal sensitive. During crystallization of MAPbBr3 precursors from solution was found that a certain structural change exhibiting an increase in electrical conductance takes place in the presence of MABr. The setup of PLA substrate and measuring electrode system creates great opportunities for study of other perovskite materials and may be able to uncover some of the mysteries that these fascinating materials hold.
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