• Korean Journal of Materials Research
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• v.29 no.5
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• pp.297-303
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• 2019

A triple-layered $PMMA/Ni_{64}Zr_{36}/PDMS$ hydrogen gas sensor using hydrogen permeable alloy and flexible polymer layers is fabricated through spin coating and DC-magnetron sputtering. PDMS(polydimethylsiloxane) is used as a flexible substrate and PMMA(polymethylmethacrylate) thin film is deposited onto the $Ni_{64}Zr_{36}$ alloy layer to give a high hydrogen-selectivity to the sensor. The measured hydrogen sensing ability and response time of the fabricated sensor at high hydrogen concentration of 99.9 % show a 20 % change in electrical resistance, which is superior to conventional Pd-based hydrogen sensors, which are difficult to use in high hydrogen concentration environments. At a hydrogen concentration of 5 %, the resistance of electricity is about 1.4 %, which is an electrical resistance similar to that of the $Pd_{77}Ag_{23}$ sensor. Despite using low cost $Ni_{64}Zr_{36}$ alloy as the main sensing element, performance similar to that of existing Pd sensors is obtained in a highly concentrated hydrogen atmosphere. By improving the sensitivity of the hydrogen detection through optimization including of the thickness of each layer and the composition of Ni-Zr alloy thin film, the proposed Ni-Zr-based hydrogen sensor can replace Pd-based hydrogen sensors.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.82-85
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• 2008

We are working towards large-area arrays of thin film transistors on polymer substrates using roll-to-roll (R2R) processes exclusively. Self-aligned imprint lithography (SAIL) is an enabler to pattern and align submicron features on meter-scaled flexible substrates in the R2R environment. The progress, current status and remaining issues of this new fabrication technology are presented.

• Carbon letters
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• v.14 no.4
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• pp.255-258
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• 2013

Flexible transparent conducting films (TCFs) were fabricated by dip-coating single-wall carbon nanotubes (SWCNTs) onto a flexible polyethylene terephthalate (PET) film. The amount of coated SWCNTs was controlled simply by dipping number. Because the performance of SWCNT-based TCFs is influenced by both electrical conductance and optical transmittance, we evaluated the film performance by introducing a film property factor using both the number of interconnected SWCNT bundles at intersection points, and the coverage of SWCNTs on the PET substrate, in field emission scanning electron microscopic images. The microscopic film property factor was in an excellent agreement with the macroscopic one determined from electrical conductance and optical transmittance measurements, especially for a small number of dippings. Therefore, the most crucial factor governing the performance of the SWCNT-based TCFs is a SWCNT-network structure with a large number of intersection points for a minimum amount of deposited SWCNTs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.71-72
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• 2006

We report on plasma damage free chemical vapor deposition technique for the thin film passivation of organic light emitting diodes (OLEDs), organic thin film transistor (OTFT) and flexible displays using catalyzer enhanced chemical vapor deposition (CECVD). Specially designed CECVD system has a ladder-shaped tungsten catalyzer and movable electrostatic chuck for low temperature deposition process. The top emitting OLED with thin film $SiN_x$ passivation layer shows electrical and optical characteristics comparable to those of the OLED with glass encapsulation. This indicates that the CECVD technique is a promising candidate to grow high-quality thin film passivation layer on OLED, OTFT, and flexible displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1455-1458
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• 2008

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) are fabricated on flexible organic polymer foil substrates. As-fabricated performance, electrical bias-stability at elevated temperatures, electrical response under mechanical flexing, and prolonged mechanical stability of the TFTs are studied. TFTs made on plastic at ultra low process temperatures of $150^{\circ}C$ show initial electrical performance like TFTs made on glass but large gate-bias stress instability. An abnormal saturation of the instability against operation temperature is observed.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.221-224
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• 2009

New type simple, thin and flexible display unit with an exchangeable image-sheet coupled with a thin film light waveguide illuminated by color LEDs is proposed It displays the still picture like an e-paper, and the imagesheet with grooves formed by the PC and the cutting plotter can be easily replaced by another one.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.200-200
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• 2012

We investigated a flexible transparent film using the spinning multi-walled carbon nanotubes (MWCNTs). Spin-capable MWCNTs on iron catalyzed on a SiO2 wafer was grown by chemical vapor deposition, which was performed at $780^{\circ}C$ using C2H2 and H2 gas. The average diameter and length of MWCNTs grown on the substrate were ~15 nm and $250{\sim}300{\mu}m$, respectively. The MWCNT sheets were produced by continuously pulling out from well-aligned MWCNTs on a substrate. The MWCNT sheet films were produced simply by direct coating on the flexible film or grass. The thickness of sheet film was remarkably decreased by alcohol spraying on the surface of sheet. The alcohol splay increased transmittance and decreased electrical resistance of MWCNT sheet films. Single and double sheets were produced with sheet resistance of ~699 and ${\sim}349{\Omega}/sq$, respectively, transmittance of 81~85 % and 67~72%, respectively. The MWCNT sheet films were heated through the application of direct current power. The flexible transparent heaters showed a rapid thermal response and uniform distribution of temperature. In addition, MWCNT yarns were prepared by spinning a bundle of MWCNTs from vertically super-aligned MWCNTs on a substrate, and field emission from the tip and side of the yarns was induced in a scanning electron microscope. We found that the field emission behavior from the tip of the yarn was better than the field emission from the side. The field emission turn-on voltages from the tip and side of MWCNT yarns were 1.6 and $1.7V/{\mu}m$, respectively, after the yarn was subjected to an aging process. Both the configuration of the tip end and the body of the yarn were changed remarkably during the field emission. We also performed the field emission of the sheet films. The sheet films showed the turn on voltage of ${\sim}1.45V/{\mu}m$ during the field emission.

• 한국전기화학회:학술대회논문집
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• 2003.10a
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• pp.43-43
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.73-75
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• 2007

Micro-cell LC film and polymer network liquid crystal (PNLC) film by using continuous compatible process have been developed . A high-contrast micro-cell LC film has a strong potential as a high-performance flexible device. PNLC film has the low driving voltage. Both films show the characteristics of lightness, thinness and mechanical stability.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.105-110
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• 2020

Cu/PET composite films are widely used in a variety of wearable electronics. Lifetime of the electronics is determined by adhesion between the Cu film and the PET substrate. The formation of an anisotropic nanostructure on the PET surface by surface modification can enhance Cu/PET interfacial adhesion. The shape and size of the anisotropic nanostructures of the PET surface can be controlled by varying the surface modification conditions. In this work, the effect of Cu/PET interface nanostructures on the failure mechanism of a Cu/PET flexible composite film is studied. From observation of the morphologies of the anisotropic nanostructures on plasma-treated PET surfaces, and cross-sections and surfaces of the fractured specimens, the Cu/PET interface area and nanostructure width are analyzed and the failure mechanism of the Cu/PET film is investigated. It is found that the failure mechanism of the Cu/PET flexible composite film depends on the shape and size of the plasmatreated PET surface nanostructures. Cu/PET interface nanostructures with maximal peel strength exhibit multiple craze-crack propagation behavior, while smaller or larger interface nanostructures exhibit single-path craze-crack propagation behavior.