• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.529-529
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• 2006

Several laboratories worldwide have demonstrated the feasibility of producing amorphous silicon thin film transistor (TFT) arrays at temperatures that are sufficiently low to be compatible with flexible foils such as stainless steel or high temperature polyester. These arrays can be used to fabricate flexible high information content display prototypes using a variety of different display technologies. However, several questions must be addressed before this technology can be used for the economic commercial production of displays. These include process optimization and scale-up to address intrinsic electrical instabilities exhibited by these kinds of transistor device, and the development of appropriate techniques for the handling of flexible substrate materials with large coefficients of thermal expansion. The Flexible Display Center at Arizona State University was established in 2004 as a collaboration among industry, a number of Universities, and US Government research laboratories to focus on these issues. The goal of the FDC is to investigate the manufacturing of flexible TFT technology in order to accelerate the commercialization of flexible displays. This presentation will give a brief outline of the FDC's organization and capabilities, and review the status of efforts to fabricate amorphous silicon TFT arrays on flexible foils using a low temperature process. Together with industrial partners, these arrays are being integrated with cholesteric liquid crystal panels, electrophoretic inks, or organic electroluminescent devices to make flexible display prototypes. In addition to an overview of device stability issues, the presentation will include a discussion of challenges peculiar to the use of flexible substrates. A technique has been developed for temporarily bonding flexible substrates to rigid carrier plates so that they may be processed using conventional flat panel display manufacturing equipment. In addition, custom photolithographic equipment has been developed which permits the dynamic compensation of substrate distortions which accumulate at various process steps.

• Journal of Information Display
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• v.6 no.2
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• pp.1-6
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• 2005

We demonstrated stability-enhanced liquid crystal (LC) displays using pixel-isolated LC mode in which LC molecules are isolated in pixel by horizontal polymer layer and vertical polymer wall. The device shows good electro-optic properties against external point or bending pressure due to the polymer structures. The polymer wall acts as supporting structure from mechanical pressure and prevents the cell gap from bending. Moreover, the polymer layer acts as an adhesive to ensure a tight attachment of the two substrates. We present herein various methods for producing polymer structures by using an anisotropic phase separation from LC and polymer composites or patterned micro-structures for stable flexible liquid crystal displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1546-1549
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• 2006

We have developed $EPLaR^{TM}$, a new way of making flexible electrophoretic displays. The TFTs have the same good performance, reliability and mature manufacturing processes as TFTs used in LCD monitors and LCD-TVs. We are working with partners to show that plastic displays can be made in existing TFT-LCD factories alongside glass LCDS. In this talk we describe the EPLaR process and show results for TFT arrays on plastic made in a factory by standard ${\alpha}$-Si TFT processing.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.277.2-277.2
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• 2014

For next-generation electronic applications, human-machine interface devices have recently been demonstrated such as the wearable computer as well as the electronic skin (e-skin). For integration of those systems, it is essential to develop many kinds of components including displays, energy generators and sensors. In particular, flexible sensing devices to detect some stimuli like strain, pressure, light, temperature, gase and humidity have been investigated for last few decades. Among many condidates, a pressure sensing device based on organic field-effect transistors (OFETs) is one of interesting structure in flexible touch displays, bio-monitoring and e-skin because of their flexibility. In this study, we have investigated a flexible e-skin based on highly sensitive, pressure-responsive OFETs using microstructured ferroelectric gate dielectrics, which simulates both rapidly adapting (RA) and slowly adatping (SA) mechanoreceptors in human skin. In SA-type static pressure, furthermore, we also demonstrate that the FET array can detect thermal stimuli for thermoreception through decoupling of the input signals from simultaneously applied pressure. The microstructured highly crystalline poly(vinylidene fluoride-trifluoroethylene) possessing piezoelectric-pyroelectric properties in OFETs allowed monitoring RA- and SA-mode responses in dyanamic and static pressurizing conditions, which enables to apply the e-skin to bio-monitoring of human and robotics.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1767-1770
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• 2007

The key development issues in the flexible displays are TFT backplane technology for their various applications, which requires competitive device performance as well as its low temperature process. In this paper, with shortly reviewing recent flexible display development status, we describe technical trends of low-temperature a-Si TFTs. Our TFTs show good device characteristics enough to apply LCD and electrophoretic display.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.51.1-51.1
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• 2015

OLED commercialization has been led in mobile market by Samsung since 2007, but more suppliers in Korea, China and Japan are joining the market. However, there remain some challenges in expanding its application to large size TV and flexible displays, especially in competition with dominant LCD products. This talk will discuss future prospects of the OLED technology after brief review of the progress.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.179-181
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• 2008

Major display equipment suppliers introduced equipment using inkjets for manufacturing steps such as printing polyimide alignment layers and color filters. This paper discusses how inkjets can be used in the development of flexible displays and materials printing systems designed to meet the challenges of fluids and process development.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.77-81
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• 2020

Commercialization of flexible OLED displays, such as rollable and foldable displays, has attracted tremendous interest in next-generation display markets. However, during bending deformation, cracking and delamination of thin films in the flexible display panels are the critical bottleneck for the commercialization. Therefore, measuring mechanical properties of the fragile thin films in the flexible display panels is essential to prevent mechanical failures of the devices. In this study, tensile properties of the metal and ceramic nano-thin films were quantitatively measured by using a direct tensile testing method on the water surface. Elastic modulus, tensile strength, and elongation of the sputtered Mo, MoTi thin films, and PECVD deposited SiN_x thin films were successfully measured. As a result, the tensile properties were varied depending on the deposition conditions and the film thickness. The measured tensile property values can be applied to stress analysis modeling for mechanically robust flexible displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1297-1300
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• 2008

Electrical stress degradation of low temperature, amorphous silicon thin film transistors is reviewed, and the implications for various types of flexible circuitry including active matrix backplanes, integrated drivers and general purpose digital circuitry are examined. A circuit modeling tool that enables the prediction of complex circuit degradation is presented.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.609-613
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• 2005

Advanced mobile communication devices require a bright, high information content display in a small, light-weight, low power consumption package. In this paper we will outline our progress towards developing such a low power consumption active-matrix flexible OLED ($FOLED^{TM}$) display. Our work in this area is focused on three critical enabling technologies. The first is the development of a high efficiency long-lived phosphorescent OLED ($PHOLED{TM}$) device technology, which has now proven itself to be capable of meeting the low power consumption performance requirements for mobile display applications. Secondly, is the development of flexible active matrix backplanes, and for this our team are employing poly-Si TFTs formed on metal foil substrates as this approach represents an attractive alternative to fabricating poly-Si TFTs on plastic for the realization of first generation flexible active matrix OLED displays. Unlike most plastics, metal foil substrates can withstand a large thermal load and do not require a moisture and oxygen permeation barrier. Thirdly, the key to reliable operation is to ensure that the organic materials are fully encapsulated in a package designed for repetitive flexing. We also present progress in operational lifetime of encapsulated T-PHOLED pixels on planarized metal foil and discuss PHOLED encapsulation strategy.