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Device for automatic measurement of volt-ampere characteristics
Ondráček, Petr ; Vrba, Kamil (referee) ; Lattenberg, Ivo (advisor)
The Master's thesis discusses the design and realization of electronic meter of volt-ampere characteristics using Wifi module ESP32. The device is designed to be able to measure the characteristic in the voltage range of +/- 20 V and current range of +/- 200 mA. The device is controlled by web interface. The user is able to connect to it with for example his or her smartphone. This interface enables the user to configure various parameters, including the range of measurement and the power restriction. Furthermore, it is possible to graphically display the measured characteristic and export the data. To be independent on the outer network, the ESP32 is operated as an access point, which is creating a new simple network without the internet connection. In the Master's thesis, the principle of voltage and current measurement is explained theoretically, the circuit connection of device and the printed circuit board are designed and the cover of the device is modeled. Also the process of creating the device according to the design is described and the cover of the device is printed on 3D printer. After that, the control program is designed, described and uploaded into the resulting device. Finally, the functionality of the device is tested by measuring the volt-ampere characteristics of a few components.
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Preparation and optimization of perovskite solar cells
Puváková, Alžbeta ; Zmeškal, Oldřich (referee) ; Weiter, Martin (advisor)
Perovskite solar cells are part of third generation of solar cells and thanks to their atractive properties they are potencional candidates for replacement of silicon solar cells. Inverted planar structure of perovskite solar cells is possible to prepare by low temperature methods and by solution processing techniques. Main aim of this thesis was to prepare and characterize inverted planar perovskite solr cells with a different modification of structure. Perovskite solar cells was prepared with following structures: reference perovskite solar cells, perovskite solar cells with only a perovskite layer, perovskite solar cell without electron transport and perovskite solar cell without hole transport layer. They were prepared simultaneously by spin coating. Methods used for a characterisation of a parameters of this cells were current-voltage characteristic, impedance spektroskopy, meassure of external quantum efficiency and electrolumiscence. Reference perovskite solar cell reached best results folowed by solar cell without hole transport layer. Lowest results were gained by perovskite solar cell without electron transport layer and perovskite solar cell with only perovskite layer, where increased recombination and acumulation of charge were observed,
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Electrical characterization of a unipolar transistor with a graphene channel
Žeravík, František ; Lednický, Tomáš (referee) ; Gablech, Imrich (advisor)
This work deals with basic properties of graphene, methods of its synthesis, doping, transfer, characterization and description of basic properties and fabrication of field-effect transistor with graphene channel. The practical part focuses on electrical characterization of a field-effect transistor with graphene channel. Concretely on measuring the channel resistance, its dependence on gate voltage, finding the Dirac point and determining the dependence of the channel conductivity on the annealing lenght. Lastly, the shift of the Dirac point and the change of the electrical properties of graphene during bending of a MEMS structure with a unipolar transistor with a graphene channel are investigated.
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Characteristics of semiconductor BSE electron microscope detector
Plot, Vítězslav ; Hubálek, Jaromír (referee) ; Boušek, Jaroslav (advisor)
The thesis deals with the characterization of a semiconductor detector of backscattered electrons. The theoretical part describes two types of electron microscopes, the interaction of the primary beam with the sample and individual types of electrons and radiation arising during the interaction. The most used types of electron detectors in scanning electron microscope are summarized. The basic characteristics of the semiconductor backscattered electron detector and their measurement methods are described. The experimental part deals with measuring the characteristics of the detector made by Delong Instruments and comparing it with commercially available detectors. Volt-ampere characteristic and dark current, the dependence of the gain on the accelerating voltage, as well as the time response of the detector were measured.
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Electrical characterization of a unipolar transistor with a graphene channel
Žeravík, František ; Lednický, Tomáš (referee) ; Gablech, Imrich (advisor)
This work deals with basic properties of graphene, methods of its synthesis, doping, transfer, characterization and description of basic properties and fabrication of field-effect transistor with graphene channel. The practical part focuses on electrical characterization of a field-effect transistor with graphene channel. Concretely on measuring the channel resistance, its dependence on gate voltage, finding the Dirac point and determining the dependence of the channel conductivity on the annealing lenght. Lastly, the shift of the Dirac point and the change of the electrical properties of graphene during bending of a MEMS structure with a unipolar transistor with a graphene channel are investigated.
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Preparation and optimization of perovskite solar cells
Puváková, Alžbeta ; Zmeškal, Oldřich (referee) ; Weiter, Martin (advisor)
Perovskite solar cells are part of third generation of solar cells and thanks to their atractive properties they are potencional candidates for replacement of silicon solar cells. Inverted planar structure of perovskite solar cells is possible to prepare by low temperature methods and by solution processing techniques. Main aim of this thesis was to prepare and characterize inverted planar perovskite solr cells with a different modification of structure. Perovskite solar cells was prepared with following structures: reference perovskite solar cells, perovskite solar cells with only a perovskite layer, perovskite solar cell without electron transport and perovskite solar cell without hole transport layer. They were prepared simultaneously by spin coating. Methods used for a characterisation of a parameters of this cells were current-voltage characteristic, impedance spektroskopy, meassure of external quantum efficiency and electrolumiscence. Reference perovskite solar cell reached best results folowed by solar cell without hole transport layer. Lowest results were gained by perovskite solar cell without electron transport layer and perovskite solar cell with only perovskite layer, where increased recombination and acumulation of charge were observed,
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Device for automatic measurement of volt-ampere characteristics
Ondráček, Petr ; Vrba, Kamil (referee) ; Lattenberg, Ivo (advisor)
The Master's thesis discusses the design and realization of electronic meter of volt-ampere characteristics using Wifi module ESP32. The device is designed to be able to measure the characteristic in the voltage range of +/- 20 V and current range of +/- 200 mA. The device is controlled by web interface. The user is able to connect to it with for example his or her smartphone. This interface enables the user to configure various parameters, including the range of measurement and the power restriction. Furthermore, it is possible to graphically display the measured characteristic and export the data. To be independent on the outer network, the ESP32 is operated as an access point, which is creating a new simple network without the internet connection. In the Master's thesis, the principle of voltage and current measurement is explained theoretically, the circuit connection of device and the printed circuit board are designed and the cover of the device is modeled. Also the process of creating the device according to the design is described and the cover of the device is printed on 3D printer. After that, the control program is designed, described and uploaded into the resulting device. Finally, the functionality of the device is tested by measuring the volt-ampere characteristics of a few components.
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