• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.329-329
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• 2008

To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, noncontact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. In this study, we investigated liquid crystal (LC) alignment with ion beam (IB) that non contact alignment technique on polyimide and electro-optical characteristics of twisted nematic (TN)-liquid crystal display (LCD) on the poly imide under various ion beam angles. In this experiment, Polyimide layer was coated on glass by spin-coating and Voltage-transmittance(VT) and response time characteristics of the TN cell were measured by a LCD evaluation system. The good characteristics of the nematic liquid crystal (NLC) alignment with the ion beam exposure poly imide surface was observed. The tilt angle of NLC on the PI surface with ion beam exposure can be measured under $1^{\circ}4 for all of irradiation angles. In addition, it can be achieved the good ED properties, and residual DC property of the ion beam aligned TN cell on polyimide surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.343-343
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• 2014

We reported on the electrical, optical, structural and morphological properties fabricated by co-sputtering for use as an anode for organic solar cells (OSCs). By adjusting RF and DC power of $MoO_3$ and IZO targets during co-sputtering, we fabricated the $MoO_3$-IZO electrode with graded content of the $MoO_3$ on the IZO films. At optimized $MoO_3$ thickness of 20 nm, the $MoO_3$ graded IZO electrode showed a higher mobility ($33cm^2/V-Sec$) than directly deposited $MoO_3$ on IZO film ($26cm^2/V-Sec$). At visible range (400nm~800nm), optical transmittance of the $MoO_3$ graded IZO electrode is higher than that of directly deposited $MoO_3$ on IZO film. High mobility of $MoO_3$ graded on IZO is attributed to less interface scattering between $MoO_3$ and IZO. To investigate the feasibility of $MoO_3$ graded IZO films, we fabricated conventional P3HT:PCBM based OSCs with $MoO_3$ graded IZO as a function of MoO3 thickness. The OSC fabricated on the $MoO_3$ graded IZO anode showed a fill factor of 66.53%, a short circuit current of $8.121mA/cm^2$, an open circuit voltage of 0.592 V, and a power conversion efficiency of 3.2% comparable to OSC fabricated on ITO anode and higher than directly deposited $MoO_3$ on IZO film. We suggested possible mechanism to explain the high performance of OSCs with a $MoO_3$ graded IZO.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.232.1-232.1
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• 2014

The green displays are the human friendly displays, the nature friendly displays, and the economical displays. Electrochromic displays are low cost and environmental devices because they do have more choice of colours and use much less power. The elements of the electrochromic devices consist of at least two conductors, an electrochromic material and an electrolyte. The optical properties were obtained using the optical contrast between the transparency of the substrate and the coloured state of the electrochromic materials. These devices can be fully flexible and printable. Due to the characteristics of the high coloration efficiency and memory effects, the electrochromic devices have been used in various applications such as information displays, smart windows, light shutters and electronic papers. Among these technical fields switchable mirrors have been received much attention in the applicative point of view of various electronic devices production. We have developed a novel silver (Ag) deposition-based electrochromic device for the reversible electrodeposition (RED) system. The electrochromic device can switch between transparent states and mirror states in response to a change in the applied voltage. The dynamic range of transmittance percent (%) for the fabricated device is about 90% at 550 nm wavelength. Also, we successfully fabricated the large area RED display system using the parted electrochromic cells of the honey comb structure.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.478.1-478.1
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• 2014

We investigated $MoO_3$ graded ITO electrodes for organic solar cells (OSCs) without PEDOT:PSS buffer layer. The effect of $MoO_3$ thickness on the electrical, optical, and structural properties of $MoO_3$ graded ITO anodes prepared by RF/DC magnetron co-sputtering system using $MoO_3$ and ITO targets was investigated. At optimized conditions, we obtained $MoO_3$ graded ITO electrodes with a low sheet resistance of 13 Ohm/square, a high optical transmittance of 83% and a work function of 4.92 eV, comparable to conventional ITO films. Due to the existence of $MoO_3$ on the ITO electrodes, OSCs fabricated on $MoO_3$ graded ITO electrode without buffer layer successfully operated. Although OSCs fabricated on ITO anode without buffer layer showed a low power conversion efficiency of 1.249%, OSCs fabricated on $MoO_3$ graded ITO electrode without buffer layer showed a outstanding cell performance of 2.545%. OSCs fabricated on the $MoO_3$ graded ITO electrodes exhibited a fill factor of 61.275%, a short circuit current of 7.439 mA/cm2, an open circuit voltage of 0.554 V, and a power conversion efficiency of 2.545%. Therefore, $MoO_3$ graded ITO electrodes can be considered a promising transparent electrode for cost efficient and reliable OSCs because it could eliminate the use of acidic PEDOT:PSS buffer layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.473.1-473.1
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• 2014

We report on the characteristics of Zr-doped $In_2O_3$ (IZrO) films prepared by DC-RF magnetron cosputtering of $In_2O_3$ and $ZrO_2$ targets for use as a transparent electrode for high efficient organic solar cells (OSCs). The effect of $ZrO_2$ doping power on electrical, optical, structural, and surface morphology of the IZrO film was investigated in detail. At optimized $ZrO_2$ RF power of 50 W, the IZrO film exhibited a low sheet resistance of 20.71 Ohm/square, and a high optical transmittance of 83.9 %. Furthermore, the OSC with the IZrO anode showed a good cell-performance: fill factor of 61.71 %, short circuit current (Jsc) of $8.484mA/cm^2$, open circuit voltage (Voc) of 0.593 V, and power conversion efficiency (PCE) of 3.106 %. In particular, the overall OSC characteristics of the cell with the IZrO anode were comparable to those of the OSC with the conventional Sn-doped $In_2O_3$ (FF of 65.03 %, Jsc of $8.833mA/cm^2$, Voc of 0.608 V, PCE of 3.495 %), demonstrating that the IZrO anode is a promising alternative to ITO anode in OSCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1100-1106
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• 2004

In this paper, we intend to make fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C：H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the alignment material of a-C：H thin film as working gas at 30 W rf bias condition. A high pretilt angle of about 5 $^{\circ}C$ by ion beam (IB) exposure on the a-C：H thin film surface was measured. Consequently, the high pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C：H thin film surface as working gas at 30 W rf bias condition can be achieved. An excellent voltage-transmittance (V -T) and response time curve of the IE-aligned FFS-LCD was observed with oblique IB exposure on the a-C：H thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IE exposure on the a-C：H thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.114.2-114.2
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• 2017

Transparent film heaters (TFHs) based on Joule heating are currently an active research area. However, TFHs based on an indium tin oxide (ITO) monolayer have a number of problems. For example, heating is concentrated in part of the device. Also, heating efficiency is low because it has high sheet resistance ($R_S$). Resistance of indium zinc oxide (IZO) is similar to ITO and it can be used to flexible applications due to its amorphous structure. To solve these problems, our study introduced hybrid layers of IZO/Ag/IZO deposited by magnetron sputtering, and the electrical, optical, and thermal properties were estimated for various thickness of the metal interlayer. It was found that the sheet resistance of the multilayer was mainly dependent on the thickness of the Ag layers. The $R_S$ of IZO(40)/Ag/IZO(40nm) multilayer was 5.33, 3.29, $2.15{\Omega}/{\Box}$ for Ag thickness of 10, 15, and 20nm, respectively, while the $R_S$ of an IZO monolayer(95nm) was $59.58{\Omega}/{\Box}$. The optical transmittance at 550nm for the IZO(95nm) monolayer is 81.6%, and for the IZO(40)/Ag/IZO(40nm) multilayers with Ag thickness 10, 15 and 20nm, is for 72.8, 78.6, and 63.9%, respectively. The defrost test showed that the film with the lowest RS had the highest heat generation rate (HGR) for the same applied voltage. The results indicated that IZO(40)/Ag(15)/IZO(40nm) multilayer has the best suitable property, which is a promising thin film heater for the application in vehicle windshield.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.124-127
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• 2002

LC aligning capabilities and the variation of pretilt angles with ion beam irradiation on the a-C:H thin films, and electro-optical (EO) performances of the ion beam aligned twisted nematic (TN)-liquid crystal display (LCD) with oblique ion beam exposure on the a-C:H thin film were studied. A high pretilt angle of $3.5{^{\circ}}$ via ion beam irradiation on the a-C:H thin film was measured. Also, the LC pretilt angle decreased due to the increase in surface roughness at over 2 min of IB exposure time. It is considered that this roughness increase due to increasing IB exposure time that generated destroy of oriented rings of atoms related to LC alignment. An excellent voltage-transmittance (V-T) curve of the ion beam aligned TN-LCD was observed with oblique ion beam exposure on the a-C:H thin film for 1 min. Also, a faster response time for the ion beam aligned TN-LCD with oblique ion beam exposure on the a-C:H thin film for 1 min can be achieved. Finally, the residual DC property of the ion beam aligned TN-LCD with ion beam exposure of 1 min on the a-C:H thin film is almost same as that of the rubbing aligned TN-LCD on a PI surface.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.65-74
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• 2009

Device quality indium tin oxide (ITO) films are deposited on glass substrates and ultra-thin diamond-like carbon films are deposited as a buffer layer on ITO by a pulsed Nd:YAG laser at 355 nm and 532 nm wavelength. ITO films deposited at room temperature are largely amorphous although their optical transmittances in the visible range are > 90%. The resistivity of their amorphous ITO films is too high to enable an efficient organic light-emitting device (OLED), in contrast to that deposited by a KrF laser. Substrate heating at $200^{\circ}C$ with laser wavelength of 355 nm, the ITO film resistivity decreases by almost an order of magnitude to $2{\times}10^{-4}\;{\Omega}\;cm$ while its optical transmittance is maintained at > 90%. The thermally induced crystallization of ITO has a preferred <111> directional orientation texture which largely accounts for the lowering of film resistivity. The background gas and deposition distance, that between the ITO target and the glass substrate, influence the thin-film microstructures. The optical and electrical properties are compared to published results using other nanosecond lasers and other fluence, as well as the use of ultra fast lasers. Molecularly doped, single-layer OLEDs of ITO/(PVK+TPD+$Alq_3$)/Al which are fabricated using pulsed-laser deposited ITO samples are compared to those fabricated using the commercial ITO. Effects such as surface texture and roughness of ITO and the insertion of DLC as a buffer layer into ITO/DLC/(PVK+TPD+$Alq_3$)/Al devices are investigated. The effects of DLC-on-ITO on OLED improvement such as better turn-on voltage and brightness are explained by a possible reduction of energy barrier to the hole injection from ITO into the light-emitting layer.