Publications Search Results

Now showing 1 - 10 of 19
  • Publication
    Transfer of the sputter technique for deposition of strongly thermochromic VO2-based coatings on ultrathin flexible glass to large-scale roll-to-roll device
    ( 2022-02-24)
    Rezek, Jiri
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    Vlček, Jaroslav
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    Čerstvý, Radomír
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    Houška, Jiří
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    The reversible semiconductor-to-metal transition of vanadium dioxide (VO2) makes VO2-based coatings a promising candidate for thermochromic smart windows, reducing the energy consumption of buildings. We report on transfer of the sputter technique for deposition of strongly thermochromic ZrO2/W-doped VO2/ZrO2 coatings on ultrathin (0.1 mm) flexible glass from a laboratory-scale device with three (V, W and Zr) planar magnetron targets to a large-scale roll-to-roll device with two (W-doped V and ZrO2) rotatable magnetron targets. The depositions were performed at a relatively low substrate surface temperature (330-350 °C) and without any substrate bias voltage. The W-doped VO2 layers were deposited using a reactive high-power impulse magnetron sputtering with a pulsed O2 flow control. We compare the process parameters used in both deposition devices and explain the basic principle of this sputter technique using the discharge characteristics measured during a large-scale roll-to-roll deposition. We characterize the design, structure (X-ray diffraction) and optical properties (spectrophotometry and spectroscopic ellipsometry) of the three-layer coatings. The coatings prepared on ultrathin flexible glass using the large-scale roll-to-roll device at a temperature close to 350 °C exhibit a low transition temperature of 22 °C, an integral luminous transmittance over 45% and a modulation of the solar energy transmittance approaching 10%. This is a promising first step to a cost-effective and high-rate preparation of large-area thermochromic VO2-based coatings for future smart-window applications.
  • Publication
    Roll to Roll Deposition of Transparent Electrodes on Permeation Barrier Coatings
    The European project PI-SCALE has set an objective to create a virtual pilot manufacturing line for various types of OLED lighting devices. An important part of this virtual pilot line is the roll-to-roll sputtering of the anode layer. An indium tinoxide (ITO) layer with a sheet resistance below 30 Osq (ohm/square) was sputtered onto a continuously moving polyethylene terephthalate (PET) film substrate using a rotatable magnetron. The sputtering performance of a bonded ITO target was compared to the performance of a plasma sprayed ITO target. It was demonstrated that the variation of the hydrogen content of the sputtering gas atmosphere can serve as a powerful parameter for the optimization of the layer properties. This gas was varied between zero and ten percent of the total gas flow. The PET film was equipped with a planarizing layer and a permeation barrier coating on top of it. It was shown how the permeation barrier is prevented from getting deteriorated by conveying the film. The removal of a protective interleaf film directly before entering the sputtering zone turned out to be decisive for the layer quality. The same holds true for the application of a protective interleaf immediately after leaving the sputtering zone. By applying these two steps, the permeation barrier could be kept below 1×10-3 g/m2day, which is the lower limit of the applied coulometric measurement device.
  • Publication
    Pulsed Magnetron Sputtering of Strongly Thermochromic VO2-Based Coatings with a Transition Temperature of 22 °C onto Ultrathin Flexible Glass
    ( 2020)
    Barta, Tomas
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    Vlcek, Jaroslav
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    Houska, Jiri
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    Cerstvy, Radomir
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    Haviar, Stanislav
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    The reversible semiconductor-to-metal transition of vanadium dioxide (VO2) makes VO2-based coatings a promising candidate for thermochromic smart windows, reducing the energy consumption of buildings. This paper deals with maximizing the application potential of these coatings in terms of their performance, an industry-friendly preparation technique, and an industrially relevant substrate. We present a scalable sputter deposition technique for the preparation of strongly thermochromic ZrO2/V0.984W0.016O2/ZrO2 coatings on ultrathin flexible glass and standard glass at a relatively low substrate surface temperature (330 °C) and without any substrate bias voltage. The V0.984W0.016O2 layers were deposited by a controlled high-power impulse magnetron sputtering of a V target, combined with a simultaneous pulsed dc magnetron sputtering of a W target. We explain the fundamental principles of this technique using the discharge characteristics measured for both discharges. We characterize the coating structure (X-ray diffraction) and a wide range of optical properties (spectrophotometry and spectroscopic ellipsometry). We find that the coatings combine a transition temperature of 22 °C, a luminous transmittance approaching 50%, a modulation of the solar energy transmittance over 10% and a temperature-independent color. The results in general, and the successful transfer from a standard glass to the ultrathin flexible glass in particular, are crucial for future applications of the coatings on smart windows.
  • Patent
    Vorrichtung zum Beschichten eines bandförmigen Substrates
    Die Erfindung betrifft eine Vorrichtung zum Beschichten eines bandförmigen Substrates, umfassend eine Beschichtungseinrichtung und eine Kühleinrichtung mit zumindest einem Oberflächenbereich, welchen das bandförmige Substrat zum Zeitpunkt des Beschichtens zumindest teilweise berührt. Dabei besteht eine Randschicht des Oberflächenbereichs der Kühleinrichtung, aus einem Kunststoff, welcher eine säulenförmige Struktur aufweist, wobei die Säulen der säulenförmigen Struktur mit einer Säulenhöhe im Bereich von 50 µm bis 500 µm und mit einem Säulenquerschnitt im Bereich von 300 µmbis 10.000 µmausgebildet sind.
  • Publication
    Roll-to-Roll Sputter Deposition of Low Resistance Electrodes on Ultrathin Glass
    ( 2019) ;
    Garner, Sean
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    Pollack, Gerd
    Ultrathin glass is a new flexible material. It is distinguished from its polymer counterparts by a couple of outstanding properties. Most importantly, the permeation barrier for moisture and oxygen is virtually infinite. Thus, lifetime problems for organic electronics can effectively be avoided. Further, the possibility to exert heat on the substrate offers considerable advantages for transparent conductive oxides. The paper features the roll-to-roll sputter deposition of indium tin oxide (ITO) based transparent electrodes. The deposition technology was the dual anode sputtering from a rotatable ceramic target. The paper provides results for ITO coatings which were either deposited at substrate temperatures of up to 300°C or which were annealed at those temperatures after the deposition. The lowest resistivity of the coatings was 1.6x10-4 Ohm-cm, corresponding to a sheet resistance of less than 11 Ohm/square.This value is much better compared to ITO coatings deposited at room temperature or annealed to moderate temperaturelevels around 150 °C. In addition to the optical and electrical properties, surface roughness and mechanical stability are also crucial propertiesfor the applicability of the substrates.Various annealing routes were compared. The indium tinoxide properties achieved by room temperature and subsequent annealing were related to those obtained by the depositionon a heated substrate. Besides the transmission, reflection and resistivity, atomic force microcopy and X-ray diffraction results were also included in the discussion.
  • Publication
    Roll-to-roll sputtering of indium tin oxide layers onto ultrathin flexible glass
    ( 2019) ; ; ;
    Vondkar, Komal
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    Ottermann, Clemens
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    Berendt, Markus
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    Pollak, Gerd
    Ultrathin flexible glass is a material with fascinating properties. However, the handling of the glass as well as the reliable and cost effective deposition of coatings onto its surface are decisive for creating attractive application cases. Indium-tin-oxide coatings were deposited onto the glass in a specially designed roll-to- roll coating machine. The substrate was heated while it was moved through the deposition zone. The minimum sheet resistance and the resistivity of these layers were 11 Osqu and 1.5 × 10−4 Ocm, respectively. The surface topography of the samples was investigated by scanning electron microscopy and atomic force microscopy. The measurement revealed that the roughness of the samples shows a minimum for substrate temperatures of 190 °C during the deposition.
  • Publication
    Vacuum coating on polymer films for outdoor applications
    This paper discusses functionalization of ETFE webs by vacuum roll-to-roll deposition of permeation barrier layers and highly conductive transparent electrodes for outdoor applications. A 100 nm thick gas barrier layer (zinc-tin-oxide - ZTO) and a 60nm thick transparent conductive layer stack(indium-tin-oxide - ITO 25 nm - Ag 10 nm -ITO 25 nm) achieve a water vapor transmission rate of 0.01 g/m²d (at38°C/90% r.h.) and sheet resistance of< 6 O/sq on a commercial grade ETFE film. However, the elastic properties of ETFE as well as its creep-behavior require specific attention during roll-to-roll processing and for design of the functional layer stacks. Inconsequence, layer thicknesses and material selection must be balanced between functional performance and the ability to survive deformation of the polymer web. This paper compares functional performance and crack formation under strain load of different layer stacks on both PET and ETFE substrates.
  • Publication
    Roll-to-roll sputtering of oxide layers into ultrathin flexible glass
    ( 2018) ;
    Dietsch, Tina
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    Ottermann, Clemens
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    Linß, Volker
    Ultrathin flexible glass is a new material with fascinating properties. However, the handling of the glass as well as the reliable and cost effective deposition of coatings onto its surface are decisive for creating attractive application cases. Fraunhofer FEP and VON ARDENNE GmbH operate together a new roll-to-roll coating machine. This equipment is specifically designed for meeting the needs of this sensitive new type of substrate. Indium-tin-oxide coatings were deposited onto the glass while it is kept at elevated temperatures. This is realized by a heater array which can adjust temperature set points up to 350 °C. The sheet resistance and the resistivity of these layers were11 Ohm per square and 1.7 x10-4O·cm, respectively. The coated glass is destined for use as transparent electrodes inorganic light emitting diodes (OLED). The poster will demonstrate how the layer properties can be fine-tuned by the process parameters during the sputter deposition. The roughness and the structural properties of the layers will be presented apart from the opto-electronic properties.
  • Publication
    Roll-to-roll deposition of permeation barrier layers using a rotatable dual magnetron sputtering system
    ( 2018)
    Himmler, Anika
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    Linß, Volker
    High performance permeation barrier coatings are usually multilayer stacks consisting of inorganic and organic layers. Besides the water vapor transmission rate the optical properties of such layers have a high importance. This study focuses on the deposition of silicon oxynitride as the inorganic layer. This material attracts a widespread interest due to its varying refractive index depending on its oxygen and nitrogen content. The experiments were carried out in a roll-to-roll coating machine using a rotatable magnetron system. The layers were deposited by reactive pulsed magnetron sputtering using targets of one meter length. It was established that the ratio of oxygen and nitrogen in the layer was not only determined by the reactive gas mixture but also by the chosen set point of the closed loop control. Both the Secondary Ion Mass Spectrometry and the Glow Discharge Optical Emission Spectroscopy (GDOS) measurements revealed a vertically different composition of the SiOxNy layers. This result was attributed to the fact that the substrate passes zones of different plasma density during the deposition process. A model for the description of the optical properties was developed on the basis of these observations. A five layer system was introduced in place of the SiOxNy single layer. These five sub-layers differed in their dispersion relation in accordance with the results of the GDOS measurement. The model provided an excellent description of the measured transmittance spectra.
  • Publication
    Roll-to-roll processing of functional films for flexible electronics
    ( 2018) ; ;
    Kudlacek, Pavel
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    Manders, Wiel
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    Mogck, Stefan
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    Keibler, Claudia
    The European Flexible OLED Pilot Line PI-SCALE aims to provide a full process chain for flexible OLED lighting modules on both polymer and thin glass substrates. This paper discusses roll-to-roll processing of substrates suitable for flexible OLEDs, addressing transparent electrode deposition on permeation barrier films as well as handling and roll-to-roll electrode coating on ultrathin glass. Functional polymer substrates with water vapor transmission rates below 10-6 g/(m²d) at 20°C / 50% r.h., defect density below 0.3 cm-2 and transparent conductor coatings with less than 30 Ohm (ITO) and less than 12 O(oxide-metal-oxide) are reported. Successful roll-to-roll deposition of ITO on ultra-thin glass is demonstrated with a sheet resistance less than 12 O.