• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.913-918
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• 2005

It is expected that the inkjet technology offers prospect for reliable and low cost manufacturing of FPD (Flat Panel Display). This inkjet technology also offers a more simplified manufacturing process for various part of the FPD than conventional process. For example, recently the novel manufacturing processes of color filter (C/F) in LCD, or RGB patterning in OLED by inkjet printing method have been developed. This elaborates will be considered as the precious point of manufacturing process for the mass production of enlarged-display panel with a low price. On this point of view, we would like to review the status of inkjet technology in FPD, with some results on forming micro line by inkjet patterning of suspension type silver nano ink as below. We have studied the inkjet patterning of synthesized aqueous silver nano-sol on interface-controlled ITO glass substrate. Furthermore, we designed the conductive ink for direct inkjet patterning on bare ITO glass substrate. The first, the highly concentrated polymeric dispersant-assisted silver nano sol was prepared. The high concentration of batch-synthesized silver nano sol was possible to 40 wt%. At the same time the particle size of silver nanoparticles was below $10{\sim}20nm$. The second, the synthesized silver nano sol was inkjet - patterned on ITO glass substrate. The connectivity and width of fine line depended largely on the wettability of silver nano sol on ITO glass substrate, which was controlled by surfactant. The relationship was understood by wetting angle. The line of silver electrode as fine as $50{\sim}100\;{\mu}m$ was successfully formed on ITO glass substrate. The last, the direct inkjet-patternable silver nano sol on bare ITO glass substrate was designed also.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.19.2-19.2
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• 2010

Printed electronics using printing process has broadened in all respects such as electrics (lighting, batteries, solar cells etc) as well as electronics (OLED, LCD, E-paper, transistor etc). Copper is considered to be a promising alternative to silver for printed electronics, due to very high conductivity at a low price. However, Copper is easily oxidized, and its oxide is non-conductive. This is the highest hurdle for making copper inks, since the heat and humidity that occurs during ink making and printing simply accelerates the oxidation process. A variety of chemical treatments including organic capping agents and metallic coating have been used to slow this oxidation. We have established synthetic conditions of copper nanoparticles (CuNPs) which are resistant to oxidation and average diameter of 20 to 50nm. Specific resistivity should be less than $4\;{\mu}{\Omega}{\cdot}cm$ when sintered at lower temperature than $250^{\circ}C$ to be able to apply to conductive patterns of FPCBs using ink-jet printing. Through this study, the parameters to control average diameter of CuNPs were found to be the introduction of additive agent, the feeding rate of reducing agent, and reaction temperature. The CuNPs with various average diameters (58, 40, 26, 20nm) could be synthesized by controlling these parameters. The dispersed solution of CuNPs with an average size of 20 nm was made with nonpolar solvent containing 3 wt% of binder, and then coated onto glass substrate. After sintering the coated substrates at $250^{\circ}C$ for 30 minutes in nitrogen atmosphere, metallic copper film resulted in a specific resistivity of $4.2\;{\mu}{\Omega}{\cdot}cm$.

• Korean Journal of Materials Research
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• v.26 no.10
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• pp.561-569
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• 2016

$SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphorescent phosphors were synthesized using the polymerized complex method. Generally, phosphorescent phosphors synthesized by conventional solid state reaction show a micro-sized particle diameter; thus, this process is restricted to applications such as phosphorescent ink and paint. However, it is possible to synthesize homogeneous multi-component powders with fine particle diameter by wet process such as the polymerized complex method. The characteristics of $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ powders prepared by polymerized complex method with one and two step calcination processes were comparatively analyzed. Temperatures of organic material removal and crystallization were observed through TG-DTA analysis. The crystalline phase and crystallite size of the $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphorescent phosphors were analyzed by XRD. Microstructures and afterglow characteristics of the $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphors were measured by SEM and spectrofluorometry, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.458.2-458.2
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• 2014

We have demonstrated that simple brush-painted Ti-doped $In_2O_3$(TIO) films can be used as a cost effective transparent anodes for organic solar cells (OSCs). We examined the RTA effects on the electrical, optical, and structural properties of the brush painted TIO electrodes. By the direct brushing of TIO nanoparticle ink and rapid thermal annealing (RTA), we can simply obtain TIO electrodes with a low sheet resistance of 28.25 Ohm/square and a high optical transmittance of 85.48% under atmospheric ambient conditions. Furthermore, improvements in the connectivity of the TIO nano-particles in the top region during the RTA process play an important role in reducing the resistivity of the brush-painted TIO anode. In particular, the brush painted TIO films showed a much higher mobility ($33.4cm^2/V-s$) than that of previously reported solution-process transparent oxide films ($1{\sim}5cm^2/V-s$) due to the effects of the Ti dopant with higher Lewis acid strength (3.06) and the reduced contact resistance of TIO nanoparticles. The OSCs fabricated on the brush-painted TIO films exhibited cell-performance with an open circuit voltage (Voc) of 0.61 V, shot circuit current (Jsc) of $7.90mA/cm^2$, fill factor (FF) of 61%, and power conversion efficiency (PCE) of 2.94%. This indicates that brush-painted TIO film is a promising cost-effective transparent electrode for printing-based OSCs with its simple process and high performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.1
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• pp.31-36
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• 2020

An investigation was conducted to determine whether the ratio of the fluid to the charged particles affects the panel reflexibility rate and the drifting current flowing in the panel, in electrophoretic-based electronic paper. In this regard, three panels were produced in this study with the ratio of the charged particles to the fluid set as 1:5, 1:1, and 5:1. Each sample was driven using an identical input pulse, for which the current flowing in the panel and the output voltage of the photodiode were measured for the panel reflexibility rate. Consequently, the drifting current initially exhibited a peak value and a saturated value at a later point. This value was proportional to the ratio of the charged particles, and it was similar to this ratio when it is higher than 1:1. The output voltage of the photodiode due to the panel reflexibility rate was proportional to the ratio of the charged particles. However, the response speed decreased if the ratio was higher than 1:1. It is expected that the results of this study will contribute to the analysis of the charging of charged particles in electrophoretic-based electronic paper, and the selection of an appropriate concentration.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1552-1555
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• 2005

We have studied the inkjet patterning of synthesized aqueous silver nano-sol on interface-controlled ITO glass substrate. Furthermore, we designed the conductive ink for direct inkjet patterning on bare ITO glass substrate. The first, the highly concentrated polymeric dispersant-assisted silver nano sol was prepared by variation of molecular weight and control of initial nucleation and growth of silver nanoparticles. The high concentration of batch-synthesized silver nano sol was possible to 40 wt%. At the same time the particle size of silver nanoparticles was below $10{\sim}20nm$. The second, the synthesized silver nano sol was inkjet - patterned on ITO glass substrate. The connectivity and width of fine line depended largely on the wettability of silver nano sol on ITO glass substrate, which was controlled by surfactant. The relationship was understood by wetting angle. The fine line of silver electrode as fine as $50{\sim}100\;{\mu}m$ was successfully formed on ITO glass substrate. The last, the direct inkjet-patternable silver nano sol on bare ITO glass substrate was designed also.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.231-236
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• 2016

A three-electrode type reflective display (electronic paper) is designed to apply an independent electric field to each three electrodes of the cell including two electric-type of particles and electrically neutral color fluid, so single color realization is possible. In particular, the movement of particles and optical properties are decided by the electric field between two electrodes on the lower substrate. So, the effect of electric field by the distance between two electrodes on the lower substrate is studied with electrode spacing with $10{\mu}m$, $15{\mu}m$, $20{\mu}m$, and $25{\mu}m$. By our experimentation, the driving voltage induces more reliable movement of charged particles and the optical properties as compared with the threshold voltage. We ascertain the single color realization and non-inverted particle separation is possible. So the more desirable optical properties are observed in case of the short electrode like $10{\mu}m$.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.464-467
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• 2005

In this paper, we present techniques to manufacture color electronic ink for multi-color electrophoretic display implementation. The charged color pigments have been prepared to have superior affinity for dielectric fluid. White $TiO_2$ nanoparticles were modified with poly(methyl methacrylate) copolymer for a microencapsulated electrophoretic display system, in order to reduce the density mismatch between nanoparticles and dielectric medium. These color balls and white pigment particle suspensions were microencapsulated through the typical microencapsulation technique. We fabricate the microcapsules to the single layer on flexible ITO substrate to test the multi-color electrophoretic display application.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.3
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• pp.1-11
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• 2007

To evaluate the quality of waste paper used for the manufacture of linerboard, the types of papers and foreign materials in compressed waste paper currently used were investigated. The recycled fibers were obtained from printing paper, newspaper, wrapping paper, white coated paperboard and corrugated container. Their fibers were observed by using a microscope, and the mechanical properties of the recycled papers manufactured from the recycled fibers were investigated. The compressed wastepaper was composed of 54% paperboard, 20% printing paper, and 20% newsprint. The content of foreign materials was about 4%, showing higher contents compared to 1% of foreign substances provided by Korea paper manufacturers' association. The types of foreign materials were various, which include vinyls, plastics, metals, woods, styrofoams, and cloths. Sound fibers were generally observed in the recycled fibers of printing papers and wrapping paper. The recycled fibers of white coated board, corrugated container and newsprint showed to be generally damaged. The whiteness of each recycled fiber were highly affected by pulp bleaching and ink-particle mixing conditions. The values of breaking length and burst index were lower than those for corrugating medium and liner board specified in KS. Although the anatomical characteristics of recycled fibers varied, their strengths appeared to be similar. This result may be explained by the use of non-deinked fiber.

• Journal of Electrochemical Science and Technology
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• v.13 no.1
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• pp.100-111
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• 2022

This paper presents a simple and inexpensive method to fabricate chemically and mechanically resistant hot electron-emitting composite electrodes on reusable substrates. In this study, the hot electron emitting composite electrodes were manufactured by doping a polymer, nylon 6,6, with few different brands of carbon particles (graphite, carbon black) and by coating metal substrates with the aforementioned composite ink layers with different carbon-polymer mass fractions. The optimal mass fractions in these composite layers allowed to fabricate composite electrodes that can inject hot electrons into aqueous electrolyte solutions and clearly generate hot electron- induced electrochemiluminescence (HECL). An aromatic terbium (III) chelate was used as a probe that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons and during injection of hot electrons into aqueous solution. Thus, the presence of hot, pre-hydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by HECL. The study shows that the extreme pH conditions could not damage the present composite electrodes. These low-cost, simplified and robust composite electrodes thus demonstrate that they can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry.