• Korean Journal of Materials Research
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• v.17 no.10
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• pp.516-520
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• 2007

Indium tin oxide, which is used as transparent conducting layer in flexible device, is deposited on PET film by a magnetron sputtering in 300 mm wide roll-to-roll process (vacuum web coating). Sheet resistance, specific resistance and transmittance is differed by sputtering parameters such as working pressures, oxygen partial pressure, and thickness of ITO layer. ITO layer is deposited about 90 nm at roll speed of 0.24 m/min and its sputtering power is 3 kW. From the XRD spectrum deposited ITO layer is verified as amorphous. Under working pressure varied from $3{\times}10^{-4}\;Torr$ to $2{\times}10^{-3}\;Torr$, sheet resistance is lowest at the working pressure of $1{\times}10^{-3}\;Torr$ and its value is from $110\;{\Omega}/{\square}$ to $260\;{\Omega}/{\square}$ at the thickness of 90 nm. Oxygen partial pressure also varies sheet resistance and is optimized at the regime from 0.2% ($1.8{\times}10^{-6}\;Torr$) to 0.6% ($6{\times}10^{-6}\;Torr$). In this oxygen partial pressure sheet resistance is lower than $150\;{\Omega}/{\square}$. As ITO layer thickness increases, sheet resistance decreases down to $21\;{\Omega}/{\square}$ and specific resistance is about $7.5{\times}10.4{\Omega}cm$ in 340 nm thickness ITO layer. Transmittance is measured at the wavelength of 550 nm and is about 90% for 180 nm thickness ITO/PET.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.203-203
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• 2012

The SWCNTs network are formed on various plastic substrates such as poly(ethylene terephthalate) (PET), polyimide (PI) and soda lime glass using roll-to-roll printing and spray process. Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of CNT film by selective removal of CNTs. Furthermore, selective cutting of carbon nanotube using a femtosecond laser does not cause any phase change in the CNTs, as usually shown in focused ion beam irradiation of the CNTs. The patterned SWCNT films on transparent substrate can be used electrode layer for touch panels of flexible or flat panel display instead indium tin oxide (ITO) film.

• International Journal of Internet, Broadcasting and Communication
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• v.6 no.1
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• pp.13-15
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• 2014

We develop a method to fabricate a flexible thin film audio systems using polyvinylidene fluoride(PVDF). The system we designed showed the properties of increased flexibility, transparency, and sound pressure levels. As an input port of two terminals, transparent oxide thin film with a low resistivity is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double-layered structure. In the range of visible light, the output from the output of the system showed a increased and improved sound pressure level. The piezoelectric polymer film of PVDF is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.396-396
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• 2012

$TiO_2$ anatase nanotube arrays (NTAs) were grown by electrochemical anodization and followed annealing of Ti foil. Ethylene glycol/$NH_4F$-based organic electrolyte was used for electrolyte solution and using second anodization process to obtain free-standing NTAs. After obtaining NTAs, ITO film was deposited by sputtering process on bottom of NTAs. UV-curable NOA was used for attach free-standing NTAs on flexible plastic substrate (PEN). Solid state electrolyte (spiro-OMeTAD) was coated via spin-coating method on top of attached NTAs. Ag was deposited as a counter electrode. Under AM 1.5 simulated sunlight, optical characteristics of devices were investigated. In order to use flexible polymer substrate, processes have to be conducted at low temperature. In case of $TiO_2$ nano particles (NPs), however, crystallization of NPs at high temperature above $450^{\circ}C$ is required. Because NTAs were conducted high temperature annealing process before NTAs transfer to PEN, it is favorable for using PEN as flexible substrate. Fabricated flexible solid-state DSSCs make possible the preventing of liquid electrolyte corrosion and leakage, various application.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.57-60
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• 2009

The conductive coating method was used for a various industrial fields. For example, Sputtering process is using to a coat of ITO layer in LCD or OLED panel manufacture process and fabricate a base layer of substrate of an electric printing device. However, conventional coating process (beam sputtering, spin coating etc.) has a problems in the industrial manufacturing process. These processes have a very high cost and critical manufacturing environment as a vacuum process. Recently, many researchers were proposed a various printing process instead of conventional coating process. In this paper, we propose an ESD printing process in ITO coating layer and apply to fabricate a conductive coating film. Ours transparent electrode had a surface resistance of about $66{\Omega}/{\square}$ and transparent of 74% in the wavelength of 500nm. This transparent electrode manufacturing process will be applied to Roll-to-Roll process. In addition, we developed roll printing process system for the next generation flexible solar cell.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.474-475
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• 2009

As a substitute of ITO material, carbon nanotube (CNT) is widely studied for transparent conductive film (TCF). Current sheet resistance of CNT-TCF is about 100 ${\Omega}$/sq at 80% transmittance. But CNT-TCF performance in manufacturable level is about 500 ${\Omega}$/sq at 83% based on the Topnanosys Co's result. Therefore, critical issue in CNT-TCF research is to reduce the sheet resistance with manufacturing reliability. In this report, recent developments using CNT-TCF are introduced. Touch panel, transparent LED signboard, transparent speaker and transparent heater are representative examples. Also I describe the future issues and prospect of CNT-TCF for the flexible display.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.380-381
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• 2007

This paper reports on the deposition conditions and properties of ITO films used as electrode layer in a organic light emitting diodes on a PET substrate. The deposition technique employed was specially designed roll-to-roll sputtering. The oxide was deposited at room temperature in an argon and oxygen plasma on a transparent conducting ITO layer on a PET film. The influence of deposition parameters such as DC power, working pressure and oxygen partial pressure has been investigated, in order to obtain the best compromise between a high deposition rate and adequate electro-optical properties. Electrical and optical properties of ITO films were analyzed by Hall measurement examinations with van der pauw geometry at room temperature and UV/Vis spectrometer analysis, respectively. In addition, the structural properties and surface smoothness were measured by x-ray diffraction and scaning electron microscopy, respectively. From optimized ITO films grown by roll-to-roll sputter system, good electrical$(6.44{\times}10^{-4}\;{\Omega}-cm)$ and optical(above 86 % at 550 nm) properties were obtained. Also, the ITO films exhibited amorphous structure and very flat surface beacause of low deposition temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.381-382
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• 2007

IZO/Ag/IZO (IAI) anode films for flexible organic light emitting diodes (OLEDs) were grown on PC (polycarbonate) substrate using DC sputter (IZO) and thermal evaporator (Ag) systems as a function of Ag thickness. To investigate electrical and optical properties of IAI stacked films, 4-point probe and UV/Vis spectrometer were used, respectively. From a IAI stacked film with 12nm-thick Ag, sheet resistance of $6.9\;{\Omega}/{\square}$ and transmittance of above 82 % at a range of 500-550 nm wavelength were obtained. In addition, structural and surface properties of IAI stacked films were analyzed by XRD (X-ray diffraction) and SEM (scanning electron microscopy), respectively. Moreover, IAI stacked films showed dramatically improved mechanical properties when subjected to bending both as a function of number of cycles to a fixed radius. Finally, OLEDs fabricated on both flexible IAI stacked anode and conventional ITO/Glass were fabricated and, J-V-L characteristics of those OLEDs were compared by Keithley 2400.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.615-616
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• 2005

Carbon Nanotubes (CNT) on flexible indium tin oxide (ITO) PET films were prepared for dye-sensitized solar cell (DSSC). These CNTs were prepared by spray coating method for various amount of light transparency. Also, Pt counter electrode was prepared by electro deposition method. All $TiO_2$ electrodes were deposited on ITO-PET films by spray coating method. Micro structural images show that CNT counter electrodes prepared by spray-coating have more dense structure with increasing spraying time (0 to 60 seconds). DSSC consisting of $TiO_2$ electrode and CNT counter electrode was fabricated with various amount of light absorption. DSSC have higher light energy conversion efficiency with increasing the thickness of CNT counter electrode. CNT counter electrode is at least compatible to that of CNT counter electrode.

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.128-132
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• 2009

Transparent conducting thin films of indium tin oxide(ITO) co-sputtered with aluminum-doped zinc oxide(AZO) were deposited on glass substrate by dual magnetron sputtering. It was found that the electrical properties and structural characteristics of the films are significantly changed according to the sputtering power of the AZO target. The IAZTO film prepared with D.C power of ITO at 100 W and R.F power of AZO at 50 W shows an electrical resistivity of $4.6{\times}10^{-4}{\Omega}{\cdot}cm$ and a sheet resistance of $30{\Omega}/{\square}$ (for 150 nm thick). Besides of the improvement of the electrical properties, compared to the ITO films deposited at the same process conditions, the IAZTO films have very smooth surface, which is due to the amorphous nature of the films. However, the electrical conductivity of the IAZTO films was found to be deteriorated along with the crystallization in case of the high temperature deposition (above $310^{\circ}C$). In this work, high quality amorphous transparent conductive oxide layers could be obtained by mixing AZO with ITO, indicating possible use of IAZTO films as the transparent electrodes in OLED and flexible display devices.