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Development of Light Emitting Electroluminescent Device by Means of Material Printing
Hrabal, Michal ; Syrový,, Tomáš (oponent) ; Boušek, Jaroslav (oponent) ; Vala, Martin (vedoucí práce)
The topic of this thesis is development of a printed alternating current powder-based phosphor electroluminescent (ACPEL) light source. It is the only present technology suitable for fabrication of large area, flexible and patterned light sources by the means of material printing and so it represents a promising alternative to some traditional light sources. Emphasis is placed on introduction and investigation of some red brick wall problems associated with this technology. These are a limited hue of colors of emitted electroluminescent light and an operation lifetime of panels exposed to environment. The first part of this thesis is focused on identification of suitable deposition techniques and their operation conditions leading to reproducible preparation of panels followed by determination of appropriate physical parameters suitable to characterize large area light sources. Therefore relevant coating and printing techniques are introduced along with their practical advantages and disadvantages with respect to preparation of the ACPEL panels. A photometric quantity luminance L together with electric energy consumption P was evaluated to determine driving conditions for a suitable application of ACPEL panels. The maximum luminance L = 133 cd•m2 was achieved on a blue panel driven by Upp = 500 V and f = 1000 Hz. Achieved values of power consumption per unit area are (7 ± 3) mW make the light sources based on this technology interesting for practical applications. The effect of driving conditions on stability of panels together with means to improve a long term stability of ACPEL panels is important topic this thesis deals with. Parameters L50 and L75 were established from the values of spectral irradiance. It was found that increasing the frequency has a negative effect on the long term stability of panels. A panel driven by 3 times higher frequency with the same voltage showed almost 3 times less values of L50 and L75 with the same type of lamination while a panel encapsulated by glass showed almost 7 times higher stability than the laminated panel. Optimal stability conditions were achieved when the driving frequency was set between 400 Hz and 800 Hz with robust encapsulation between two glass panels. Limited hue of colors of light emitted by ACPEL panels is one of the known problems this thesis addresses. This work investigates a promising method, an addition of a color conversion material (CCM) with suitable spectral characteristics. A derivative of diketopyrrolopyrrole (DPP) was found to be a suitable novel CCM for blue phosphor. Using this CCM a 7-times increase of spectral irradiance of a blue panel at 580 nm was easily achieved. An ease of fabrication, very low power consumption and long life time of the developed ACPEL panels together with developed possibility to modify a hue of emitted light, make them potentially ideal light sources for low-light background illumination for example in automotive industry, safety signs in public buildings, indoor decorative illumination or “branding”etc.
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Optimalizace elektrochemického senzoru pro měření v kapce
Gajdoš, Libor ; Pekárek, Jan (oponent) ; Prášek, Jan (vedoucí práce)
Tato práce se zabývá modifikací standardního tlustovrstvého elektrochemického senzoru tak, aby na něm bylo možno provádět detekci z kapky. V teoretické části je popsána technologie tlustých vrstev, typy a složení tlustovrstvých past. Práce pokračuje teorií o smáčivosti povrchů a úvodem do elektrochemie a elektroanalytických měřicích metod. Praktická část práce se zabývá tiskem různých druhů tlustovrstvých past na keramické substráty pro stanovení jejich smáčivostí, následnou modifikací senzorů pomocí izolační tlustovrstvé pasty a napařováním Parylenu a také základním elektrochemickým proměřením z kapky pomocí těchto modifikovaných senzorů. V závěru práce je uvedeno zhodnocení naměřených výsledků.
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Textile Integrated Waveguide Components
Cupal, Miroslav ; Polívka, Milan (oponent) ; Joler, Miroslav (oponent) ; Raida, Zbyněk (vedoucí práce)
The thesis is focused on the research of structures based on the Textile Integrated Waveguide (TIW). Attention is turned to the electrical characterization of textile materials (textile substrates, yarns) to be used for the implementation of textile-integrated antennas, reconfigurable and active circuits. The thesis deals with the design of multilayer transitions between a microstrip line on a conventional substrate and textile-integrated lines. Second, a concept of the textile-integrated switch is presented. The switch is controlled by conductive posts which are connected or disconnected by DC driven PIN diodes to form open or closed walls. Finally, the design methodology for textile-integrated circularly polarized antennas operating in ISM bands up to 24 GHz is proposed. All the design procedures were verified by simulations and measurements of real samples manufactured by screen-printing using a silver polymer paste. For bonding semiconductor components, conductive silver adhesives were used. Screen-printed components were compared with reference structures manufactured from a self-adhesive copper foil.
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Textile Integrated Waveguide Components
Cupal, Miroslav ; Polívka, Milan (oponent) ; Joler, Miroslav (oponent) ; Raida, Zbyněk (vedoucí práce)
The thesis is focused on the research of structures based on the Textile Integrated Waveguide (TIW). Attention is turned to the electrical characterization of textile materials (textile substrates, yarns) to be used for the implementation of textile-integrated antennas, reconfigurable and active circuits. The thesis deals with the design of multilayer transitions between a microstrip line on a conventional substrate and textile-integrated lines. Second, a concept of the textile-integrated switch is presented. The switch is controlled by conductive posts which are connected or disconnected by DC driven PIN diodes to form open or closed walls. Finally, the design methodology for textile-integrated circularly polarized antennas operating in ISM bands up to 24 GHz is proposed. All the design procedures were verified by simulations and measurements of real samples manufactured by screen-printing using a silver polymer paste. For bonding semiconductor components, conductive silver adhesives were used. Screen-printed components were compared with reference structures manufactured from a self-adhesive copper foil.
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Development of Light Emitting Electroluminescent Device by Means of Material Printing
Hrabal, Michal ; Syrový,, Tomáš (oponent) ; Boušek, Jaroslav (oponent) ; Vala, Martin (vedoucí práce)
The topic of this thesis is development of a printed alternating current powder-based phosphor electroluminescent (ACPEL) light source. It is the only present technology suitable for fabrication of large area, flexible and patterned light sources by the means of material printing and so it represents a promising alternative to some traditional light sources. Emphasis is placed on introduction and investigation of some red brick wall problems associated with this technology. These are a limited hue of colors of emitted electroluminescent light and an operation lifetime of panels exposed to environment. The first part of this thesis is focused on identification of suitable deposition techniques and their operation conditions leading to reproducible preparation of panels followed by determination of appropriate physical parameters suitable to characterize large area light sources. Therefore relevant coating and printing techniques are introduced along with their practical advantages and disadvantages with respect to preparation of the ACPEL panels. A photometric quantity luminance L together with electric energy consumption P was evaluated to determine driving conditions for a suitable application of ACPEL panels. The maximum luminance L = 133 cd•m2 was achieved on a blue panel driven by Upp = 500 V and f = 1000 Hz. Achieved values of power consumption per unit area are (7 ± 3) mW make the light sources based on this technology interesting for practical applications. The effect of driving conditions on stability of panels together with means to improve a long term stability of ACPEL panels is important topic this thesis deals with. Parameters L50 and L75 were established from the values of spectral irradiance. It was found that increasing the frequency has a negative effect on the long term stability of panels. A panel driven by 3 times higher frequency with the same voltage showed almost 3 times less values of L50 and L75 with the same type of lamination while a panel encapsulated by glass showed almost 7 times higher stability than the laminated panel. Optimal stability conditions were achieved when the driving frequency was set between 400 Hz and 800 Hz with robust encapsulation between two glass panels. Limited hue of colors of light emitted by ACPEL panels is one of the known problems this thesis addresses. This work investigates a promising method, an addition of a color conversion material (CCM) with suitable spectral characteristics. A derivative of diketopyrrolopyrrole (DPP) was found to be a suitable novel CCM for blue phosphor. Using this CCM a 7-times increase of spectral irradiance of a blue panel at 580 nm was easily achieved. An ease of fabrication, very low power consumption and long life time of the developed ACPEL panels together with developed possibility to modify a hue of emitted light, make them potentially ideal light sources for low-light background illumination for example in automotive industry, safety signs in public buildings, indoor decorative illumination or “branding”etc.
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Effect of Plasma Oxidation of Carbon Working Electrode on Its Electrochemical Response
Koporec, Lukáš
Screen-printed electrochemical sensors are very perspective because they are much smaller than common electrodes used in electrochemistry, portable, ecological and can be very easily modified in order to increase their sensitivity and selectivity for specific analytes. In this study, plasma treatment was used to modify the carbon working electrode of a screen-printed threeelectrodes system. Plasma treatment was performed using RF plasma discharge in argon/oxygen atmosphere. The plasma modified electrodes exhibited considerable enhancement in electrocatalytic activity towards studied electroactive compounds.
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Optimalizace elektrochemického senzoru pro měření v kapce
Gajdoš, Libor ; Pekárek, Jan (oponent) ; Prášek, Jan (vedoucí práce)
Tato práce se zabývá modifikací standardního tlustovrstvého elektrochemického senzoru tak, aby na něm bylo možno provádět detekci z kapky. V teoretické části je popsána technologie tlustých vrstev, typy a složení tlustovrstvých past. Práce pokračuje teorií o smáčivosti povrchů a úvodem do elektrochemie a elektroanalytických měřicích metod. Praktická část práce se zabývá tiskem různých druhů tlustovrstvých past na keramické substráty pro stanovení jejich smáčivostí, následnou modifikací senzorů pomocí izolační tlustovrstvé pasty a napařováním Parylenu a také základním elektrochemickým proměřením z kapky pomocí těchto modifikovaných senzorů. V závěru práce je uvedeno zhodnocení naměřených výsledků.
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