National Repository of Grey Literature 158 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Model of electric charge transport in perovskites and their precursors
Raška, Vilém ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
Thesis focuses on analysis and determination of basic electric properties of perovskite materials. Thesis includes theoretical section which discusses electric properties and charge transport in solid materials. In the experimental section several chloride and boride perovskite material samples are used for measurement of VA characteristics and Impedance Spectroscopy. Then based on acquired data multiple models are created which are then used to determine required properties and state distribution of samples.
Study of influence degradation to fotovoltaic cells properties
Tulková, Tereza ; Sládek, Petr (referee) ; Zmeškal, Oldřich (advisor)
The thesis examines degradation of photovoltaic cells and modules. Degradation assessment was based on the data gathered from the photovoltaic system installed at the Pedagogical Faculty of Masaryk University in Brno, Poříčí 31. The research focuses on influence of external factors on the amount of power supplied to the grid by the system. Theoretical part of the thesis summarizes state-of-the-art knowledge about photovoltaic conversion and devices taking the advantage of the principle. The first part of the thesis describes production and application of photovoltaic cells and their impact on the environment. Second part of the thesis deals with the principle of photovoltaic conversion. Next part lists materials used for the production of photovoltaic cells and the process of encapsulation. The fourth part summarizes knowledge about degradation of photovoltaic panels. Experimental part of the thesis statistically analysis the data gathered from the above mentioned power plant. Influence of degradation factors (surface temperature of PV panel, air temperature, wind velocity and radiation intensity) on effectiveness of energy conversion was examined in particular. The published results can be applied on analysis of new projects and/or used for modification of production technological processes.
Study of Thermal Properties of Materials
Štefková, Pavla ; Pavlík, Zbyšek (referee) ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
The doctoral thesis deals with study of thermal properties of materials. Behavior of homogeneous matters at different temperatures is well described in theory and experimentally verified. Overall effect of all components of mixture and other influences related with material creation affect behaviour and properties of heterogeneous matters. For study of thermal properties can be used transient method of measurement which provide a picture about overall influence of all components of mixture on studied heterogeneous material and among others enable determination of thermophysical properties of whole macroscopic system in observed temperature range. Properties of solid matters, thin foil and liquids can be measured by means of pulse and step-wise transient method which is used for experimental activity in the thesis. It is contact measurement method and its principle is based on small quantity of heat generating inside the specimen and temperature response measuring. Theoretical part of thesis is focused on creation of method for determination of thermophysical parameters. The base is differential equation of the heat conduction. Its solution is temperature function. Three methods of evaluation are described mathematically. They start from general relations designed for study of fractal structure physical properties (maximum of function method, differential method and multi-parametric non-linear regression method).
Printed insulating interlayrs
Olejníková, Marie ; Zmeškal, Oldřich (referee) ; Dzik, Petr (advisor)
This bachelor thesis deals with preparation and study of printed insulating interlayers based on barium titanate. The composition of ink formulation and method of deposition were investigated. The composition was optimised with the type of added binder. The printing was made using a screen printing method. Characterisation of prepared layers was made using contact profilometry and optical microscopy. Dielectric properties of layers were subsequently analysed using the impedance spektroskopy method.
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.
Study of thermal properties of selected coloids
Křivánková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
The bachelor thesis is focused on the study of the thermal properties of colloidal systems, especially the properties of emulsions (water, oil), which can be used in the cosmetic industry as an essential component of various lotions and creams and in the food industry. In the introduction the first defined thermo-physical processes (conduction, convection and radiation) and temperature measurement (stationary, transient). Furthermore defined physical parameters (heat and thermal conductivity, heat capacity), that are determined using transient methods. The measured data were collected and analyzed by using the EMA (Electrical Measurement Analyser) and the HarFA (Harmonic and Fractal Image Analyser). The results will be used to determine the optimum conditions for the production of cosmetics and dietary supplements.
Optimalisation of thermal properties of solar cell modules
Dohnalová, Lenka ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
The topic of presented diploma thesis is study of thermal properties structures of photovoltaic cells. The main goal of this thesis is study of ways of heat spreading from volume and planar materials (conduction, convection and radiation). Then it is needed to determine contributions of heat spread from laminated photovoltaic cell and compare them to results measured by transient pulse method, step wise method and with thermo-camera using. At the beginning of this thesis it will be needed to define heat and ways it’s spread. Heat is closely connected with temperature. That is reason why will be there spoken about temperature and methods of its measuring. Than there will be defined basic thermo-physical parameters of materials. Thermo-physical parameters of materials will be measured by transient methods that will be characterized later and by thermo-camera. This thesis deals with photovoltaic cells, so there will be described their structure, properties, utilization and way of their production. Subsequently after the definition of all needed terms the experimental part of this thesis will be introduced. It will be needed to characterize measured volume material and define its thermo-physical parameters. Using the pulse transient method, step wise method and thermo-camera there will be measured the thermal response of PMMA sample, nonlaminated photovoltaic cell and also samples of laminated photovoltaic cells. Findings of all described methods will be finally compared.
Electric and dielectric properties of organic materials for photovoltaic applications
Florián, Pavel ; Nešpůrek, Stanislav (referee) ; Zmeškal, Oldřich (advisor)
Diploma thesis deals with the use of organic materials in photovoltaic applications and the study of their electric and dielectric properties. The theoretical part of thesis deals issue of the use of organic polymeric materials in photovoltaics and their advantages and disadvantages. Next are the results of various studies of organic solar cells by other authors. In the practical part of the work are shown experimental results (volt-ampere characteristics and impedance spectra) of samples of organic semiconductors and their evaluation.
Organic solar cells for photovoltaic conversion of solar energy
Šedina, Martin ; Zmeškal, Oldřich (referee) ; Weiter, Martin (advisor)
This work is focused to study organic materials for solar energy conversion into electricity and characterization of conversion processes. Materials and their blends with semiconducting properties such as photoconductivity were studied. Thin films of organic materials and their blends were prepared by spin-coating method and characterized by optical methods (UV-VIS and photoluminiscence spectroscopy), by current-voltage characteristics, by impedance spectroscopy method, spectral response measurement of photocurrent and method of transient photoconductivity. Structural factors influences the conversion of solar energy into electricity were observed. Based no these results, the materials and their blends useful for photovoltaic applications were determined. The dependence between photoconductivity of thin films and theirs structure was also discussed.
Study of Electric and Dielectric Properties of Alkali-Activated Aluminosilicate with Increased Electrical Conductivity
Florián, Pavel ; Pavlík, Zbyšek (referee) ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
This dissertation deals with the study of electric and dielectric properties of composite structures on the base of alkali-activated aluminosilicates with admixtures of various carbon particles. These materials fabricated from alkali-activated blast furnace slag, quarz sand, natrium water glass as alkali activator, water, dispersant and small amount of carbon admixture (carbon black, graphite powder, carbon fibers or carbon nanotubes) to increase electric conductivity may be used for example to construction of snow-melting, deicing and self-monitoring systems. Their current-voltage characteristics and impedance spectra were used for determination of electric and dielectric properties of these structures. The equivalent circuits were used for evaluation of impedance spectra. The results were correlated with thermal properties of these structures.

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