Session Index

Display Technology

Display Technology I
Friday, Dec. 4, 2015  14:10-15:40
Chair: Tsung-Hsien Lin
Room: Delta B08(B1F)
Notes: N/A
14:10 - 14:40 Paper No.  2015-FRI-S0701-I001
Invited Speaker:
Hiroyuki Yoshida
Observation of double-twist cylinder distribution in blue phase liquid crystals

Liquid crystalline cholesteric blue phases (BPs) typically appear between the cholesteric phase and the isotropic liquid in a chiral liquid crystal. They possess three-dimensional cubic structures characterized by ‘double-twist’ structures or cylinders (DTCs) in which the liquid crystal director twists along all directions perpendicular to itself. Their complex structure and properties make them interesting both as subjects of soft matter physics and as candidate mate-rials for next generation electro-optic applications. Especially, the invention of the poly-mer-stabilization technology [1] has led to various application proposals such as displays, lenses, and optical filters [2-5]. One of the challenges for the commercialization of BPs is to improve their Kerr coefficient, which is directly related to the driving voltage. The approach often employed is to use materials with large dielectric anisotropies, as the enhanced dielectric torque can lead to a significant re-duction of the required driving voltage. On the other hand, because the Kerr effect in BPs occurs as a result of the molecules reorienting within the cubic lattice, the structure also plays an important role in determining its electro-optic properties. Our group has focused on studies aimed at clarifying the structure-property relationships in BPs, with recent findings including the dependence of the Kerr coefficient on the symmetry of the BP [6], and observation of the anisotropy in electro-optic Kerr coefficient [7]. Observing the BP structure in real space can potentially aid further understanding of their structure-property relationship. We have recently succeeded in observing the distribution of DTCs in BPs by the use of a photopolymerizable liquid crystal material [8]. Photopolymerizable liquid crystals enable the fabrication of high quality films with well-controlled orientations in a standard cell structure. Observation of ultra-thin sections not only provide direct confirmation of the DTC distribution predicted from theory, but also reveals a difference in the tendencies of BPs to align on unidirectionally ‘rubbed’ substrates depending on the symmetry of BP. The wide applicability makes our approach a powerful tool for investi-gating complex liquid crystal order. This research was supported by MEXT KAKENHI (Grant #25107719), MEXT Photonics Ad-vanced Research Center Program (Osaka University), MEXT Advanced Characterization Nan-otechnology Platform Program (Osaka University), and JST PRESTO classical concept of columnar functional architecture in primary visual cortex.

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14:40 - 15:10 Paper No.  2015-FRI-S0701-O001
Hsiao-Wen Zan Low-Voltage Highly–Stable Vertical Organic Transistors

We introduce our continuous effort in developing vertical organic transistor to serve as low-voltage element on future flexible electronics. By tuning vertical geometry, high on/off ratio larger than 10000 is obtained. The vertical sidewall treatment effectively improves the transistor stability under bias stress. The key processing on large area substrate will be also introduced.

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15:10 - 15:25 Paper No.  2015-FRI-S0701-O002
Po-Chien Chang Novel Near-Infrared Organic Upconversion Device with High Sensitivity and Imaging Quality

We demonstrate a novel organic upconversion device (OUD) for near-infrared (NIR) mapping application that can convert a weak signal of NIR photon in dark environment to generate a green image of outside object on device panel. In this study, the device configuration of indium-tin oxide/mixed charge generation layer of chloroaluminum phthalocyanine and C70/1,1-bis(di-4-tolylaminophenyl) cyclohexane/4,4’-Bis(N-carbazolyl)-1,1’-biphenyl doped with bis[2-(2-pyridinyl-N)phenyl-C] (acetylacetonato)iridium(III)/2-phenyl-9-(3-(2-phenyl-1, 10-phenanthrolin-9-yl)phenyl)-1,10-phenanthroline/CS2CO3/Ag was proposed to demonstrate the OUD with high current gain and imaging quality. As a result, our device exhibited a current gain as high as 15 000 at a driving voltage of 3.2 V and clear three-dimensional imaging of a real object with high resolution of 500 dots per inch, resulting the high sensitivity of this organic device for NIR sensing compared with previous reports.

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15:25 - 15:40 Paper No.  2015-FRI-S0701-O003
Cheng-Che Lee HfO2/Al2O3 Multilayer Gate Dielectrics for P-Type SnO Thin-Film Transistors

In this paper, an HfO2/Al2O3 multilayer gate dielectric is introduced to replace the HfO2 single layer for p-channel tin monoxide (SnO) thin-film transistors (TFTs). Comparable device performance can be achieved with nearly 30% reduction in the dielectric thickness. The result can facilitate the future development of flexible SnO TFTs.

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