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Study of optoelectrical properties of organic semiconductor thin film layers of phtalocyanines
Miklíková, Zdeňka ; Vala, Martin (referee) ; Zmeškal, Oldřich (advisor)
Diploma thesis is focused on the study of optoelectric properties of thin layers of organic materials based on phthalocyanines, which can be used as an active layer of photovoltaic cells. Especially are studied the properties of the thin active layers of PdPc and PdPc + IL on the glass or ceramic substrates with aluminium contact, which are prepared by material printing here. On the prepared samples were first measured current-voltage characteristics in the dark and in the light and then were measured impedance spectrums in the dark. The received results will be used to improve the properties and structures of photovoltaic cells.
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Tungsten trioxide coatings fabricated from nanocrystalline suspension and binder
Filipská, Markéta ; Zlámal,, Martin (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with layers of tungsten oxide, which are prepared from a nanoparticle suspension and a binder. The coating composition consisted in the first case of ground tungsten oxide nanoparticles alone, then of acetylated peroxotungstic acid alone and finally of a mixture of ground tungsten oxide mixed with acetylated peroxotungstic acid. The compositions thus formed were applied to conductive FTO glass and thus act as photoanodes. A stainless steel needle is used as a counter electrode for volt-ampere measurements. The work focuses on the study of physicochemical properties of prepared photoanodes and their optimalization in order to obtain the highest possible values of generated photocurrents. The electrical properties of all cells were determined using voltammetric characteristics.
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Printed transparent oxide conductors
Bartoš, Radim ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
Thin films of tin oxide doped by fluorine or antimony were prepared by spincoating technique and material printing technique. Plenty of inorganic and organic coumpouds were used as precursors of fluorine and antimony. Sheet resistence of films were measured by 4-probe method and film thickness were determined by contact profilometer. Films were analyzed by Xray diffraction (XRD) and scan electron microscopy (SEM).
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Material printing for the preparation of sensor devices
Krnáčová, Alica ; Vošický, Libor (referee) ; Vala, Martin (advisor)
This thesis studies the relation between printing parameters, properties, and function of capacitive touch sensor. For this purpose, model prototypes of touch sensors made by screen printing were developed and subsequently characterized. Characterization was aimed at surface morphology, structure, and electrical properties. It was discovered that printing parameters in broad range have no significant impact on thickness, roughness, or capacitive behavior of prepared sensors. Nevertheless, higher printing speed produces more homogenous layer with lower porosity, which results in lower sheet resistance, hence better conductivity. In the same way, higher curing temperature causes lowering of sheet resistance by better evaporating the organic components of printing paste. Independent from printing parameters, all samples showed good response to human touch in form of small change of capacity. Using the capacitive sensor as an element in LC circuit, resonance sensor was prepared, which response to touch was under the same conditions 10x higher than the response of capacity itself. This could prove advantageous in large area applications, where the conductivity decreases in farther places due to long lines. Results of experimental work prove the reliability and suitability of screen printing as a method for printed electronics manufacturing.
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Optimalization of gel electrolyte for printed UV sensor based on photoelectrochemical cell
Vrbková, Kateřina ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
This paper deals with the construction of photoelectrochemical cell, used for detection of ultraviolet radiation as a UV sensor. Photoelectrochemical cell consists of three layers, layer of photoactive semiconductor titanium dioxide, carbon electrodes and poly(vinyl alcohol) polymer electrolyte. The sensor layer enables the detection of UV radiation with the subsequent generation of photocurrent. Material printing techniques, such as screenprinting, pad printing and inkjet printing were used to produce the cell. Gel electrolyte was characterized by optical microscopy and rheometry. Sensor functionality was verified by use of electroanalytical techniques.
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Study of the influence of the dielectrics on the optoelectronic properties of electroluminescent devices
Foldynová, Klára ; Novák, Vítězslav (referee) ; Vala, Martin (advisor)
This diploma thesis is studing the possibilities of influencing the optoelectric properties of printed light emitting panels, which work on the principle of electroluminescence excited by alternating electric field. The aim of this worrk is to monitor the influence od dielectric properties of electroluminescent phosphor binder on the targeted electroluminescence. In the theoretical part of this thesis, there are described principles of electroluminescence, suitable materials methods of characterization and preparation of panels using printing techniques. Experiment part contains electrical characterization of selected binders to determine their dielectric constants. Subsequently, printing pastes were formulated in different weight ratios of binder electroluminescent phosphor and model light-emitting panels were prepared. Optoelectric characterization was used to determine the change in irradiance. It was found that the dielectric properties of the binder significantly affect the resulting irradinace. It has same irradiance for a smaller amount od phosphor than with the binder with a low dielectric constant. The finding of this work can be used to improve the luminosity at the electroluminescent panels.
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Printed UV senor based on photoelectrochemical cell
Vičarová, Monika ; Drbohlavová, Jana (referee) ; Dzik, Petr (advisor)
This thesis deals with the construction of a photoelectrochemical cell, which is used for detection of ultraviolet radiation by means of generated photocurrent in dependence on the intensity of incident radiation. The cell construction is based on a carbon electrode system with a titanium dioxide sensory layer and a UV curable electrolyte. Printing techniques such as screen printing, inkjet printing and pad printing were used to deposit individual layers. Carbon electrodes with sensory layer were studied through profilometric analysis, optical microscopy, and four-point probes. The viscosity of the liquid formulation of uncured electrolyte was characterized by rheometric measurement. Photoelectrochemical properties of the prepared cell for use as a UV sensor were investigated by cyclic voltammetry and chronoamperometry.
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Fabrication and characterization of oxidic conductive layers
Bartoš, Radim ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
Liquid composition for antimony doped tin oxide solgel deposition was prepared. Anorganic precursors of tin and antimony were used (tin(IV) chloride, antimony(III) chloride). ATO nanoparticles were dispergated in composition. This composition was used for spincoating deposition of thin films. Composition was analyzed by thermal analysis TGA and DSC. Sheet resistence of prepared samples were examined by four probe sensing. RMS roughness and thickness was measured by profilometry. Samples were analyzed by scan electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Transmittance and haze were measured and calculated by UV-VIS spektrometry with integration sphere.
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Sol-gel process using reverse micelles
Lukešová, Magdalena ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
Práce popisuje přípravu tenkých transparentních vrstev oxidu titaničitého metodou sol-gel procesu s reverzními micelami, které jsou jedinečným uskupením zajišťujícím uniformní velikost připravených částic. Neionogenní tenzid byl použit jako templát. Pomocí materiálového tisku, tedy specializovanou formou inkoustového tisku, byly připraveny tenké filmy oxidu titaničitého nanesením 1–4 vrstev. Po kalcinaci byly připravené vrstvy oxidu titaničitého charakterizované šířkou zakázaného pásu. Struktura vrstev byla popsána optickou mikroskopií a SEM. Fotokatalytická aktivita byla ověřena oxidační reakcí 2,6-dichlorindofenolu a rozkladem kyseliny stearové, která byla přímo natištěna na vrstvy oxidu titaničitého. Fotoindukovaná změna hydrofility byla studována pomocí měření kontaktního úhlu smáčení vody. Fotokatalytická účinnost připravených filmů rostla s počtem vrstev oxidu titaničitého.
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Peroxotitanate gels suitable for piezoelectric print
Fuksa, Andrej ; Pekárková, Jana (referee) ; Veselý, Michal (advisor)
This thesis provide information about deposition of thin layers from peroxotitanate precursor. Precursor containing peroxotitanic acid and mixture of solvents (isopropanol and ethyleneglykol), was printed with the ink-jet material printer. Glass slides were used as a substrate. Prepared layers of gel did not show photocatalytic activity, therefore calcination at 450 °C, was used to a gel conversion. Structure of the layers was characterized using optical and SEM microscopy. Photoactivity of the layers was studied by a hydroxy-lation of cumarine.
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