• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.448-448
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• 2007

OLED has many advantages of low voltage operation, self radiation, light weight, thin thickness, wide view angle and fast response time to overcome existing liquid crystal display (LCD)'s weakness. Therefore, It draws attention as promising display and has already developed for manufactured goods. Also, OLED is regarded as a only substitute of flexible display with a thin display. However, Indium tin oxide(ITO) thin film for electrode of OLED shows a low electrical properties and is impossible to deposit at high thermal condition because electrical characteristics of ITO is getting worse. One of the ways to realize an improved flexible OLED is to use high internal efficiency electrodes, which have higher work function than those single layer of ITO films of the same thickness. The high internal efficiency electrodes film is developed with structure of nickel oxide for bottom Emission Type of OLED.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.413-413
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• 2007

In recent years, flexible display devices such as liquid crystal display (LCD), organic light emitting diode (OLED), etc. have attracted considerable interest in a wide variety of applications. Polymer substrate is absolutely necessary to realize this kind of flexible display devices. Using the polymer as a substrate, there are lots of advantages including not only mechanical flexibility such as rolling and bending characteristics but also light weights, low cost and so on. In detail, thickness and weights is only one forth and one second of glass substrate, respectively. However, it needs low temperature below $150^{\circ}C$ in the fabrication process comparing to conventional deposition process. The polymer substrate is not thermally stable as much as the glass substrate so that some deformation can be occurred according to variation of temperature. In particular, performance of devices can be easily deteriorated by shrinkage of substrate when heating it. In this paper, pre-annealing and deposition of buffer layer was introduced and studied to solve previously mentioned problems of the shrinkage and followed shear stress.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.53-57
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• 2019

Recently, the application field of solar panels is increasing. Accordingly, the demand for flexible devices is also steadily increasing. It is therefore necessary to develop $TiO_2$ paste for low-temperature annealing for flexible DSSC fabrication. In this study, the $TiO_2$ paste for low-temperature annealing with varying molar ratio of titanium isopropoxide (TTIP) was prepared, and DSSC was fabricated and its characteristics were compared. As a result, there was no deformation of the particles on the surface in the SEM data. However, the highest open circuit voltage, short circuit current, and fill factor were measured in the DSSC unit cell prepared by adding 0.5 mol of TTIP to the $TiO_2$ paste, and the highest efficiency was 4.148%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.1-9
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• 2023

According to the recent global warming, it is necessary to use energy efficiently together with eco-friendly energy. The development of alternative technologies is requisite for managing the current energy and climate crises. In this regard, "smart windows," which can control solar radiation, can be used to mitigate energy demands. Electrochromic devices (ECDs) effectively control the amount of solar energy reaching commercial and other living areas and maintain climate conditions via color modulation in response to small external stimuli, such as temperature and light irradiation. However, the performance and the stability of ECDs depend on the state of the electrolyte and sealing of the device. To resolve the aforementioned issues, an ECD was manufactured by using a poly (methyl methacrylate) (PMMA)-based gel polymer electrolyte (GPE), and a laminating method was used to adequately seal the ECD. The concentrations of PMMA, acetonitrile (ACN), and ferrocene (Fc) were controlled to optimize the composition of the GPE to achieve an enhanced electrochromic performance. The fabricated GPE-based ECD afforded high optical contrast (~81.92%), with high electrochromic stability up to 10,000 cycles. Moreover, the lamination method employing the GPE could be used to fabricate large-area ECDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.27-27
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• 2009

Non-stochiometric CdS:H films grown on polyethersulfon (PES) flexible polymer substrates at room temperature by R.F. sputtering technique. They exhibited a dark- and photo-sheet resistance of $2.7\times10^5$ and $\sim\;50\;{\Omega}$/square, respectively. These values were realized by an optimum control of both hydrogen doping-levels and the surface morphologies of the films. The comparison between the real and the simulated results for the shielding and the transmission by the free space measurement system in the X-band frequency range (8.2 - 12.4 GHz) was also addressed in this study. Samples overlapped with 13 layers of CdS:H/PES were consistent with the transmission results of pure aluminum metal films ($0.1\;{\Omega}$/square) deposited on PES substrates. As a result, by the simples tacking of the CdS:H/PES layers, the perfect control of the shielding and the transmission of the EM wave in the range of X-band frequency is possible by avisible light alone, and their results are especially very outstanding findings in the stealth function of the radome(Radar+Dome) such as aircrafts, ships, and missiles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.284-284
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• 2009

We have fabricated semiconductor nanocrystals using phase separation on flexible substrates for future application in QD-LEDs. The phase separation between the CdSe semiconductor nanocrystals and TPD organic underlayer can occur during the solvent drying, and the CdSe may rise towards the surface of the coated films, which is arranged into close packed array called self-assembly process. In this work, the polyethylene naphthalate (PEN) films of $200{\mu}m$ thickness was used as a flexible substrate, which was coated with indium tin oxide(ITO) as a transparent electrode of <$15{\Omega}/cm^2$. A number of solvents such as chloroform, toluene, and hexane was used and their coating properties were investigated using the spin coating process. The dispersion of both QD and TPD was rather poor in toluene and hexane and resulted in rougher surface and some aggregates. Meanwhile, the surface roughness of templates can be a very critical issue in the fabrication of QD-LED devices. Some experiments was performed to reduce the ~4nm surface roughness of the PEN films and It can be decreased to the minimum of ~0.7nm. Also discussed are the optical properties of semiconductor nanocrystals used in this phase separation and possible large area and continuous coating process for future application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.760-765
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• 2014

MgZnO has attracted a lot of attention for flexible device. In the flexible substrate, the crystal structure of the thin films as well as the surface morphology is not good. Therefore, in this study, we studied on the effects of the oxygen pressure on the structure and crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films deposited on PES substrate by using pulsed laser deposition. We used X-ray diffraction and atomic force microscopy in order to observe the structural characteristics of $Mg_{0.3}Zn_{0.7}O$ thin films. The crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films with increasing temperature was improved, Grain size and RMS of the films were increased. UV-visible spectrophotometer was used to get the band gap energy and transmittance. $Mg_{0.3}Zn_{0.7}O$ thin films showed high transmittance over 90% in the visible region. As increased working pressure from 30 mTorr to 200 mTorr, the bandgap energy of $Mg_{0.3}Zn_{0.7}O$ thin film were decreased from 3.59 eV to 3.50 eV.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.5
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• pp.939-949
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• 2017

This study uses 3D printing technology to design and fabricate a fall impact protection pad with a spacer fabric structure. The design of the pads consists of hexagonal three-dimensional units connected in a honey-comb shape; in addition, the unit consists of a surface layer and a spacer layer. Protect pads were designed as either a hexagonal type or diamond type according to the surface layer structure; subsequently, a spacer filament was also designed as the most basic I-shape type. Designed pads were printed using four types of flexible filaments to select suitable material for a fall impact protection pad. Impact protection performance and bending stiffness were evaluated for the eight type of pad outputs. As a result of the impact protection performance evaluation, when the force of 6,500N was applied, the force passed through the pad was in the range of 1,370-2,132N. FlexSolid$^{(R)}$ and Skinflex$^{TM}$ showed good protection performance and cubicon flexible filament showed the lowest protection. NinjaFlex$^{(R)}$ was found to be the most flexible in the bending stiffness evaluation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.602-607
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• 2013

Concern for the TOS (Transparent Oxide Semiconductor) is increasing with the recent increase in interest for flexible device. Especially MgZnO has attracted a lot of attention. $Mg_xZn_{1-x}O$, which ZnO-based wideband-gap alloys is tuneable the band-gap ranges from 3.36 eV to 7.8 eV. In particular, the flexible substrate, the crystal structure of the amorphous as well as the surface morphology is not good. So research of MgZnO thin films growth on flexible substrate is essential. Therefore, in this study, we studied on the effects of the oxygen partial pressure on the structural and crystalline of $Mg_{0.1}Zn_{0.9}O$ thin films. MgZnO thin films were deposited on PES substrate by using pulsed laser deposition. We used XRD and AFM in order to observe the structural characteristics of MgZnO thin films. UV-visible spectrophotometer was used to get the band gap and transmittance. Crystallization was done at a low oxygen partial pressure. The crystallinity of MgZnO thin films with increasing temperature was improved, Grain size and RMS of the films were increased. MgZnO thin films showed high transmittance over 80% in the visible region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.425-430
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• 2009

$ZrO_2$ film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets ($d_{TT}$), the distance between the target and the substrate ($d_{TS}$), and the deposition time. The $ZrO_2$ film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the $ZrO_2$ film with optimized condition ($d_{TT}$=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the $ZrO_2$ film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.