This diploma thesis is focused on the study of electric and dielectric properties of transistors based on ionic liquids. The measurements were performed on organic electrochemical transistors with a semiconducting channel made of PEDOT:PSS, which were firstly prepared on ITO substrates, later they were printed using 3D print. Ionic liquid NO4 (1-butyl-3-methylimidazolium hydrogensulfate) was used for measuring of the properties. Electrical properties were determined by measuring volt-ampere characteristics, dielectric properties were measured by impedance spectroscopy.

This master thesis is focused on analysis of reactive power flow in LV and MV networks. In the first part there is a definition of reactive power and description of individual parts of electrical networks that contribute with their reactive power to distribution network. The second part is dedicated to calculation of power flow in simulation software PSS® Sincal where on numerical models of network different types of network configuration are tested and consequently its influence on reactive power flow is evaluated. A more detailed analysis is dedicated to reactive power compensation in networks with distributed generation equipped with Volt-Var regulation and its possible negative mutual influence. This thesis also includes general recommendation on the basis of network simulation analysis concerning installation of compensating systems in distribution transformer station.

The aim of this diploma thesis is to conduct optical and photovoltaic characterization of derivatives of diketopyrrolopyrrole (DPP) as materials suitable for fabrication of bulk heterojunction organic solar cells. The charge transfer from donor material (DPP) to acceptor material (PCBM) is studied by a quenching of fluorescence. The photovoltaic response is studied by current – voltage characteristic which can tell us crucial parameters such as shor circuit current density Jsc, open circuit voltage Voc, fill factor FF and power conversion efficiency PCE. Optical characterization was carried out for symmetrical DPP derivatives (U69 and U97) which both contained diphenylaminstilbene moiety and differed in N-alkyl group. On the other hand photovoltaic characterization was conducted for analogous but asymmetrical materials (U70 and U99). Material U29 was characterized as well but its properties proved to be very poor. Both these characterizations tell us that materials with shorter solubilization groups (U69 and U99) are more suitable candidates. Achieved PCE for U70 was 0,74 % and for U99 up to 1,39 %. From these values one can say that small molecule organic materials can be used for fabrication of solar cells.

Kondenzátor na bázi oxidu niobu je novým typem pasívní součástky, jehož vývoj byl motivován snahou vyřešit hlavní nedostatky tantalového kondenzátoru – omezený zdroj tantalové suroviny a nebezpečí hoření při průrazu. Chování kondenzátoru na bázi oxidu niobu lze stejně jako u tantalového kondenzátoru popsat prostřednictvím reverzní MIS struktury. Pro studium mechanismu transportu nosičů nábojů v dielektriku Nb2O5 a pro stanovení fyzikálních parametrů, které řídí zbytkový proud, bylo využito měření V-A charakteristik v normálním a reverzním módu při 77 a 300K, dále závislosti kapacity ochuzené vrstvy na napětí a frekvenci, teplotní a časové závislosti zbytkového proudu a spektrální hustoty šumu ve frekvenční a časové doméně při různých napětích. Experimentální data potvrdila platnost navrženého pásového diagramu MIS struktury a poskytla jeho klíčové parametry. Bylo ověřeno, že transport nosičů náboje v NbO kondenzátorech je určen ohmickou, Poole-Frenkelovou a tunelovou složkou v normálním módu, a Schottkyho emisí v reverzním módu. V rozsahu standardních aplikačních napětí dominují v normálním módu Poole-Frenkelova emise a v reverzním módu Schottkyho emise. Při vyšších napětích v normálním módu určuje průrazné napětí kondenzátoru tunelový mechanismus. V reverzním módu rozhoduje o odolnosti vůči tepelnému průrazu kondenzátoru výška bariéry mezi dielektrikem a anodou. Bylo zjištěno, že NbO a Tantalové kondenzátory mají stejný mechanismus vodivosti. Specifika NbO anody se projevují pouze v rozdílných hodnotách parametrů pásového diagramu, nikoliv v principech mechanismu transportu nosičů náboje. To vysvětluje základní rozdíl mezi oběma kondenzátory, který je v kvalitě dielektrické vrstvy na přechodu anody a dielektrika. Nižší potenciálové bariéry a vyšší počet defektů v dielektriku, který je způsoben dalším stabilním oxidem, má za následek vyšší zbytkový proud NbO kondenzátoru. Tento jev však nemá žádný vliv na spolehlivost součástky. Teoretické modely a vybrané testovací metody byly použity k volbě vhodných materiálů anody, ke stanovení vhodných dopantů a k optimalizaci technologie anodické oxidace. Byla nalezena korelace mezi parametry transportu nosičů náboje a spolehlivostí, a na základě experimentálních dat byly navrženy optimalizace výrobního procesu kondenzátorů. Lepší porozumění transportním mechanismům v NbO kondenzátorech umožnilo úplný popis nové součástky na bázi oxidu niobu. Byly zdůrazněny silné a slabé stránky této nové technologie a nalezeny nástroje pro optimalizaci procesů, které umožní vyšší spolehlivost a efektivitu NbO kondenzátorů.

Спроектирована установка для нанесения органических покрытий. Установка термовакуумного нанесения и виртуальный прибор «ThermoVAC&Co» позволяют осуществлять синтез тонкопленочных покрытий, контролируя температуру нагрева испаряемого вещества до 500 °C. Выполнен синтез тонких пленок 5,11-диметил-5,11-дигидроиндоло [3.2-b]карбазола 5,11-дигексил-5,11-дигидроиндоло[3.2-b]карбазола, 5,11-бис(2-метоксиэтил)-5,11-дигидроиндоло[3,2-b]карбазола и 5,11-бис[2-(2-метоксиэтокси)этокси]-5,11-дигидроиндоло[3,2-b]карбазола для исследования оптических и электрических характеристик. С помощью конфокального микроскопа Axio CSM 700 была проведена аттестация поверхности синтезируемых покрытий. Спектры оптического поглощения были получены на спектрометре Shimadzu UV-2450. Расчетный потенциал ионизации для исследованных соединений ICZ составляет 6,82-7,1 эВ. Обсуждается влияние отдельных блоков соединений на спектр оптического поглощения. На базе микрозондовой станции Cascade Microtech MPS150 произведены измерения вольтамперных характеристик структуры ITO/-ICZ/Al. По данным ВАХ были рассчитаны подвижности зарядов по модели инжекционных токов. Подвижность носителей заряда, оцененная по вольтамперным характеристикам, находится в диапазоне 2,2 ∙ 10-9–1,43 ∙ 10-6 см2 / (В·сек) для исследованных соединений ICZ. Установлена связь между интенсивностью полос поглощения с максимумом около 430 нм и подвижностью носителей заряда. / The installation for applying organic coatings is designed. The thermal vacuum deposition unit and the «ThermoVAC & Co» virtual instrument allow the synthesis of thin-film coatings, controlling the temperature of heating the evaporated substance up to 500 ° C. The thin films of 5,11-dimethyl-5,11-dihydroindolo [3.2-b] carbazole 5,11-dihexyl-5,11-dihydroindolo [3.2-b] carbazole, 5,11-bis (2-methoxyethyl) - 5,11-dihydroindolo [3,2-b] carbazole and 5,11-bis [2- (2-methoxyethoxy) ethoxy] -5,11-dihydroindolo [3,2-b] carbazole were synthesized to study optical and electrical characteristics. The surface of the synthesized coatings was certified using the Axio CSM 700 confocal microscope. Optical absorption spectra were obtained with the Shimadzu UV-2450 spectrometer. The calculated ionization potential is 6.82–7.1 eV for the studied ICZ compounds. The effect of individual blocks of compounds on the optical absorption spectrum is discussed. The current-voltage characteristics of the ITO / -ICZ / Al structure were measured with the Cascade Microtech MPS150 microprobe station. According to the I-V characteristics data, the charge mobility was calculated using the injection current model. The mobility of charge carriers, estimated by the current-voltage characteristics, is in the range 2,2 ∙ 10-9–1,43 ∙ 10-6 cm2/ (V·sec) for the studied ICZ compounds. The relationship between the intensity of absorption bands with a maximum near 430 nm, and the mobility of charge carriers were found.

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.

Vývoj UHV kompatibilního kombinovaného systému AFM/SEM. Modifikace předchozího AFM mikroskopu pro podmínky spojené s tímto systémem. Výzkum transportu elektrického náboje v organických solárních článcích pomocí měření jejich volt-ampérových charakteristik a povrchového potenciálu. Příprava zlatých hrotů pro STM netoxickou cestou.

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 substrates, which consist of a thin active layer of phthalocyanines. On the samples were first measured current-voltage characteristics (in the dark and during the exposure) and the basic parameters of the photovoltaic conversion were determined. Finally were measured frequency dependencies (impedance spectra, in the dark and during the exposure) and the parameters of a model of the structure with organic semiconductor were determined. The obtained results will be used to optimize the properties of photovoltaic cells.

My diploma thesis is focused on a comparison of direct-current and high frequency (15-80 kHz) electric discharge, which generates non-thermal plasma in water solution of sodium chloride. Mainly current-voltage and Lissajous charts are discussed in the first part of this thesis. These charts describe different discharge phases: electrolysis, bubble formation, discharge breakdown and discharge regular operation in a pin-hole of a dielectric barrier. Influence of frequency, electrolyte conductivity, thickness of the diaphragm (or length of the capillary) and pin-hole diameter on discharge breakdown and bubble generation was studied, too. Measurements were realized in a polycarbonate reactor with total volume of 110 ml, which was divided by a changeable polyacetal insulating wall. This wall divided the reactor into two approximately equal spaces with one stainless steel planar electrode in each part. The Shapal-MTM ceramic discs (thickness of 0.3–1.5 mm and diameter of the central pin-hole of 0.3-0.9 mm) were mounted in the centre of the insulating wall. Initial conductivity of sodium chloride solution was chosen within the interval of 100900 S/cm. The second part of my thesis compares an influence of the direct-current (DC) and high frequency (HF) power sources on physical solution properties (conductivity, pH and temperature) and generation of hydrogen peroxide. A plasma reactor with total volume of 4 l and with mixing set up was divided into two equal spaces with one planar platinum electrode in each part. Diaphragm with thickness of 0.6 mm and pin-hole diameter of 0.6 mm was installed in the middle of the separating wall. Experiment was held at discharge operation of 45 W for 40 minutes with both power sources. Detection of hydrogen peroxide was realised by using a titanium reagent forming a yellow complex, which was analysed by absorption spectroscopy. If HF discharge power is plotted as a function of applied frequency, exponential decrease of frequency with increasing power can be observed. Higher breakdown voltage is necessary for thicker dielectric barriers, on the other hand for bigger diameter of the pin-hole lower breakdown voltage and higher power is needed in DC as well as in HF regime. Breakdown voltage is decreased by the increasing conductivity in both regimes; due to more charge carriers in the higher conductivity lower breakdown voltage is needed. However frequency in HF regime and DC discharge power increases. HF discharge power is decreased by the increasing conductivity. Solution conductivity and temperature are increased by initial conductivity value in both discharge regimes. Solution pH drops to acidic conditions when HF or DC positive regime is applied due to the generation of reactive species and electrolysis (in DC regime). However solution becomes alkaline when DC negative regime is applied. Concentration of hydrogen peroxide is produced linearly when HF or DC negative regime is applied and it depends on initial solution conductivity.