|
|
Advanced materials for organic bioelectronics
Sedlák, Jiří ; Salyk, Ota (referee) ; Weiter, Martin (advisor)
This bachelor thesis deals with the research of PEDOT:DBSA material for possible use in organic bioelectronics. First, a method for preparing PEDOT:DBSA layers of required thickness was standardized and the dependence of the thickness on the conductivity of the material was monitored. Subsequently, the effect of thermal stabilization and EG, DMSO and H2SO4 substances on the conductivity of prepared layers was tested. Two principles were tested to increase conductivity. The first was the principle of adding substances as dopands into liquid polymeric solutions. The second method of sample preparation was the method of secondary treatment of already prepared layers of pure PEDOT:DBSA. All of prepared polymeric layers were characterize by two methods: four point probe and profilometry.
|
|
|
Advanced materials for organic photonics
Zvěřina, Libor ; Salyk, Ota (referee) ; Weiter, Martin (advisor)
The theoretical part of this bachelor’s thesis deals with principles, structure and optimization of organic solar cells and properties of low-molecular advanced materials – diketopyrrolopyrroles, which are used in photovoltaics. In the experimental part six derivatives of diketopyrrolopyrrole were analysed by optical characterisation. It was found that N-substitution does not influence optical properties. Length of conjugated system showed to be the key parameter. The longer conjugation is, the smaller band gap and the greater absorption intensity are obtained. Based on the previous study, four materials were chosen to prepare solar cells. Influence of thermal annealing and gradual-annealing was studied. Current density, fill factor and photovoltaic conversion efficiency were increased by annealing. Gradual-annealing have not lead to further improvement. Finally, solar cells were optimized by 1,8-diiodooctane as an additive. It was found that effect of thermal annealing can be replaced with the additive. The best photovoltaic conversion efficiency was measured on the cell with 0,2 vol. % of additive in active bulk heterojunction.
|
|
|
Study of sensoric properties of organic semiconductors
Saska, Pavel ; Šedina, Martin (referee) ; Salyk, Ota (advisor)
Compounds based on diketopyrrolopyrrole are organic pigments that behave as semi-conductors. Their analogues with pyridyl side group are due to their sensitivity to hydrogen potentially useful as hydrogen sensors. The aim of this work was to examine properties of sensors with an active layer of diketopyrollopyrolle derivatives. The sensors were tested on an apparatus built for this purpose at FCH VUT in Brno. More specifically, changes to conductivity of these sensors in the presence of hydrogen under various conditions were studied.
|
|
|
Optimization of printing of organic electronic devices printing for bioelectronics
Bráblíková, Aneta ; Hrabal, Michal (referee) ; Salyk, Ota (advisor)
This bachelor thesis is focused on optimization of printing of organic electronic devices printing for bioelectronics. The main goal of this bachelor thesis is a series of experiments devised to optimize semiconductive structures of PEDOT (semiconductive polymer) and description of the process used in the preparation of organic electrochemical transistors for biosensor by screen printing technology. The research focused on application of bioelectronics, printing technologies, conductive inks suitable for the preparation of OECTs (organic electrochemical tranzistors) and rheological properties of materials. Main conditions tested in the experimental part were temperature, stirring and additon of DMSO (dimethylsulfoxide) into a printing pasted. The evaluated parameters of materials were basic viscoelastic characteristics. At the ent of the thesis have been successfully designed the series of transistors to monitor cell cultures.
|
|
|
Morphology study of organic molecular compounds thin films
Schön, Martin ; Vala, Martin (referee) ; Salyk, Ota (advisor)
This thesis deals with morphology study of organic molecular thin film compounds. The vapour deposition was used for thin films preparation. There are described used vacuum technology and measuring instruments in the theoretical part. In the second part is then described the experiment. The characteristics and morphology of thin films have been analyzed by scanning electron microscope (SEM). Influence of deposition temperature and distance between substrate holder and evaporator boat on film morphology have been analyzed. Diketopyrrolopyrrole (DPP) thin films have interesting chemical and physical properties, expecting wide range of applications, especially in electronics industry.
|
|
|
Low Energy Solid-State Converters for Energy Harvesting
Znbill, Laila ; Husák, Miroslav (referee) ; Salyk, Ota (referee) ; Boušek, Jaroslav (advisor)
Disertační práce je zaměřena na nízkoenergetické konvertory pro zpracování energie. Pro fotovoltaické generátory pracující při nízké úrovní osvětlení byly navrženy konvertory založené na konfiguraci single cell. Pomocí levných výrobních procesů a dostupných materiálů byl navržen a vyroben jednoduchý a spolehlivý termogenerátor. Výrobní postupy využívaly plazmatické aktivace povrchu pomocí výboje s dielektrickou bariérou a modifikované metody depozice PEDOT. Byly navrženy jednoduché a spolehlivé DC/DC měniče pro nízkonapěťové aplikace jako termoelektrické generátory a fotovoltaické články v konfiguraci single cell. Měniče pracují od napětí několika desítek mV a výstupní napětí může být na úrovni několika voltů. Účinnost se blíží 50% a náklady na materiál a výrobu jsou ve srovnání s použitím běžně dostupných integrovaných obvodů pro Energy Harvesting výrazně nižší. Pro řídicí obvody byly použity bipolární tranzistory, které v režimu velmi malých proudů mohou mít napájecí napětí od 0,5 V. Byla ověřena možnost výroby integrovaných obvodů s extrémně nízkým provozním napětím. Tranzistory FET zde pracují v podprahovém režimu a v režimu Bulk-driven.
|
|
|
Analysis of x-ray diphractograms of organic crystalline solids
Stejkora, Jakub ; Žídek, Jan (referee) ; Salyk, Ota (advisor)
Derivates of diketopyrrolopyrrole are colored pigments with potential use in field of organic semiconductor structures. Their electrical attributes such as conductivity, photocon¬¬ductivity and electroluminescence relate to their crystal structures that determine charge transport path through the compound. For crystallographic structure determination from RTG diffractometry it is needed to grow a measurable single crystal. Growing crystals of derivates of diketopyrrolopyrrols is very difficult due to their poor solubility in all solvents. Several relatively suitable – perhaps even measurable – samples were obtained throughout the testing of series of methods. One of these samples was measured with RTG diffractometry and on the ground of this measurement it was possible to find and solve the crystallographic structure.
|
|
|
Electrochemical characterization of bioelectronic systems
Runštuková, Nikola ; Salyk, Ota (referee) ; Ehlich, Jiří (advisor)
The aim of this thesis was electrochemical characterization of 24 microbial fuel cells platform for high-throughput screening of electrogenic microorganisms and comparison of measured values across all the fuel cells. In the theoretical part, there is a description of electrogenic bacteria, which are essential for current genereation in microbial fuel cells, description of microbial fuel cells and methods used for their characterization. In experimental part, there is a description of assembly process of the platform and measurement process. The result of this thesis is characterization of the platform before and after inoculation using open-circuit potential measurement, continuous current measurement, cyclic voltametry, linear sweep voltametry and electrochemical impedance spectroscopy. Thanks to this methods the values of open-circuit potencial, maximum power and internal resistance were obtained and their distribution was compared. These performed experiments verified the correct function of presented fuel cell platform.
|
|
|
Nanolayered Composites
Kontárová, Soňa ; Salyk, Ota (referee) ; Mistrík, Jan (referee) ; Čech, Vladimír (advisor)
Tato studie je zaměřena na základní výzkum tenkých vrstev plazmových polymerů a vliv depozičních podmínek na strukturu a vlastnosti jednotlivých vrstev a multivrstev připravených pomocí metody PE CVD. Jednotlivé vrstvy a multivrstvy a-SiC:H byly deponovány na křemíkové substráty z monomeru tetravinylsilanu (TVS) při různých výkonech v kontinuálním a pulzním režimu. Vrstvy byly rozsáhle zkoumány pomocí spektroskopické elipsometrie, nanoindentace, mikroskopie atomárních sil (AFM), rentgenové fotoelektronové spektroskopie (XPS), spektroskopie Rutherfordova zpětného rozptylu (RBS), rentgenové reflektivity, Fourierovy transformační infračervené spektroskopie (FTIR) a měření kontaktního úhlu, pro zjištění jejich optických, mechanických a chemických vlastností. Byl zkoumán a prokázán vliv depozičních podmínek na fyzikálně-chemické vlastnosti pp-TVS vrstev. Jednotlivé vrstvy byly v rámci po-depoziční úpravy vystaveny UV záření a byl zkoumán účinek stárnutí a vliv UV záření na jejich fyzikální a chemické vlastnosti. Multivrstevnaté struktury (plazmaticky polymerizované 2-vrstvy a 10-ti-vrstvy) s tloušťkou jednotlivých vrstev od 0,5 µm do 25 nm byly úspěšně deponovány a charakterizovány pomocí elipsometrické spektroskopie. Na základě získaných poznatků je možné připravit materiály s vlastnostmi upravenými podle požadavků pro využití v nanokompozitních aplikacích a optických zařízeních.
|
|
|
Contamination in semiconductor fabrication
Fojtášková, Helena ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with contamination in the production of semiconductor substrates. It focuses on the efficiency and optimization of wet cleaning processes for monocrystalline silicon and silicon carbide semiconductor wafers. The thesis includes a literature research in the field of semiconductor manufacturing, wafer contamination and wafer cleaning processes. The most commonly studied metal contaminants include iron, copper and nickel, due to their high diffusivity, and therefore these elements were chosen for the experimental part. In the experimental part, wafers were prepared by targeted contamination to verify the effectiveness of the cleaning processes. Contamination analysis was performed using the vapour phase decomposition method combined with inductively coupled plasma mass spectrometry (VPD-ICP-MS) for silicon wafers and total reflection X-ray fluorescence (TXRF) for silicon carbide wafers. Based on the measurement results, the efficiency of the washing processes was evaluated and a procedure for process optimization was recommended.
|
guest ::
