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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.
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Study population of bacteria by image analysis methods
Ševčík, Jan ; Veselá, Mária (referee) ; Zmeškal, Oldřich (advisor)
This bachelor thesis is focused on monitoring and application of image analysis methods on Bacillus megaterium and Cupriavidus necator bacteria. The introduction describes a general knowledge about bacteria, microscopic and image analysis methods. At first it was necessary to prepare suitable microscopic specimens using Gram staining for the observation of a bacteria cell. Every picture of bacteria was taken using a CCD camera and a microscope. Box–Counting method was used to identify the optimal threshold value, corresponding to their fractal measure (or surface areas covered with bacteria) and fractal dimension (or entropy of their arrangement on the surface area). After thresholding, the images were further processed using the Mass–Radius method, which defines a distribution of bacteria relative to the centroid of a cluster.
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Study of electrical and dielectric properties of thin polymer films
Miklíková, Zdeňka ; Novák, Vítězslav (referee) ; Zmeškal, Oldřich (advisor)
The thesis is focused on the study of electric and dielectric properties of thin-film organic materials that can be used as an active layer of photovoltaic cells. Primarily were studied the properties of the layers on the glass substrate, which consist of a thin active layer of mixture ZnPc/PCBM with Al or Au contact. On the selected samples were first measured current-voltage characteristics in the dark and during the exposure then on the selected samples were measured frequency dependences (impedance spectra) in the dark and finally on the selected samples were measured relaxation characteristics (transient response analysis – current dependences on time at constant voltage) in the dark. The measured data for transient measurement were evaluated using the methods of fractal analysis in HarFA. The results will be used to optimize the properties of photovoltaic cells.
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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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The study of the electrical and dielectric properties of gas sensors based on ionic liquids
Maráčková, Lucie ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
This diploma´s thesis is focused on a study of electrical and dielectric properties of gas sensors based on ionic liquids. Measurements were done on two different types of OECT substrates (0099 and 0160). Three ionic liquids and physiological solution PBS were chosen as electrolytes. Direct current current-voltage characteristic was measured. Switching rations of transistors with this electrolyte were determined by current-voltage characteristic. Alternating resistivity dependence on frequency were measured as well. Better properties showed OECT 0099 substrates.
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Synthesis and Analysis of Composite Oxide Ceramics in Presence of Nonconventional Energetic Fields
Bartoníčková, Eva ; Lapčík, Ĺubomír (referee) ; Zmeškal, Oldřich (referee) ; Cihlář, Jaroslav (advisor)
Synthesis and bulk analysis of composite ceramic oxide materials and materials with perovskite-defect structure is presented within this work. Syntheses of these advanced ceramics materials were carroed out by using of nonconventional techniques (microwave-assisted hydrothermal synthesis and polycondensation techniques) and by conventional mechanochemical activation followed by high temperature solid state reaction. X-Ray difraction (XRD), Rietveld analysis, scaning microscopy (SEM), microalysis EDS-SEM, thermal analysis (TG), infrared spectroscopy (IR), determination of particles size and specific surface area were used for description of synthesized products. In case of perovskite system based on La-Sr-Fe-Ti-O electrochemical properties were studied. Part of work was focused on chemical analysis of synthesized composite oxide materials and decomposition hard structured products by using of nonconventional fields.
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Photovoltaic power station in area South Moravia, appreciation their influence on environment
Krystýnová, Hana ; Zmeškal, Oldřich (referee) ; Kotlík, Josef (advisor)
This thesis is focused on possible utilization of the sun energy for electricity production. It points out the basic components, attributes and functions of the photovoltaic system, also the suitability of the South-Moravian region for photovoltaic power station construction. Further there are mentioned current photovoltaic power stations built in South-Moravian from the point of view of location, performance etc. It analyses potential and real possibilities of solar power utilization in the South Moravian Region in connection with the Territorial Energy Policy.
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Study of passive stabilisation of building materials temperature
Šebek, Jan ; Pavlík,, Zbyšek (referee) ; Zmeškal, Oldřich (advisor)
The topic of presented master’s thesis was study of passive stabilization of building materials temperature. The main goal of this thesis was measuring and characterization of the thermal properties of building materials, which are used to PCM technology. PCM technology is based on utilization of latent heat of phase change. At the beginning of this thesis it was needed to define physical principle of phase change, then the most usable PCM chemicals (e.g. paraffin, Glauber’s salt, hexahydrate calcium chloride) and their basic physical properties (especially thermo-physical), background research of building materials with PCM and also the methods of thermo-physical properties measurement. It was also needed to characterize measured building materials and define theirs thermal parameters; because the values of thermal parameters of measured samples were compared to these values. In the experimental part of my thesis are measurements of material thermal analysis, which are methods, where the properties of materials are studied as they change with temperature. I had used to differential scanning calorimetry, transient pulse method and other methods, which are usable for thermo-physical properties measuring and characterization. I have been much interested in properties of measured material, which were specific heat capacity, temperature diffusivity, heat conductivity and phase change temperature (the melting point of PCM). At the end of my thesis the findings of all methods were finally summarized, compared and commented.
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Study of dielectrical properties of organic material thin films
Pospíšil, Jan ; Boušek, Jaroslav (referee) ; Mikula, Milan (referee) ; Zmeškal, Oldřich (advisor)
The dissertation is focused on the study of electric and especially dielectric properties of thin film organic materials with their huge potential for optoelectronics and other industrial sectors. The theoretical part deals with the use of organic materials in organic photovoltaic cells, the methods of deposition techniques and characterization. The theoretical knowledge of the dielectric spectroscopy, including methods for determining the physical properties and evaluation of experimental data are also described. The experimental part is devoted to the study of small molecule organic solar cells with bulk heterojunction composed of electron donor molecule of DPP(TBFu)2 and electron acceptor fullerene derivatives, such as PC60BM, PC70BM and TC60BM. The experimental part is divided into two main parts. The first part deals with the study of processes occurring at the interface between the active layer and the contact; the second part is focused on transport processes inside the structure of photovoltaic cells and also contains a study of perovskite solar cells.
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Study of thermal properties of materials for solar cells lamination
Dohnalová, Lenka ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
The topic of presented bachelor´s thesis was study of thermal properties of materials for solar cells lamination. The main goal of this thesis was measuring and characterisation of the basic thermal properties of volume materials and plastic films, which are used to solar cells lamination. At first a thermal response to a concrete thermal pulse was measured by the thermoelectric thermometer. Then there was studied the distribution of temperature on the surface of a sample during heating and cooling by the non-point heat source. At the beggining of this thesis it was needed to define heat and ways it´s spread, then the basic thermal properties and also methods of their determination. The ways of measuring temperature were described and then used in praxis. My thesis deals with study of thermal properties volume materials. It was needed to characterize measured volume material and define it´s thermal parameters, because the values of thermal parameters of measured samples of lamination films were compared to these values. This thesis is concerned in solar cells too. So there were also described their structure, properties, utilization and way of their production. After the definition of all needed therms the experimental part of this thesis was begun. At first the thermal response of each of the eight different samples was measured by the pulse transient method. Then there was studied the thermal field on the surface of the sample by thermocamera through using the pulse transient method. Findings of both methods were finally compared.
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