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24. High electrical characteristics through graphene oxide doping process on physicochemically reformed inorganic thin films.

Author

Yang, Da-Bin, Oh, Jin Young, Choi, Bo-Kyeong, Lee, Dong Wook, Kim, Dong Hyun, and Seo, Dae-Shik

Subjects
GRAPHENE oxide, THIN films, VAN der Waals forces, X-ray photoelectron spectroscopy, ATOMIC force microscopy, ELECTRO-optical effects
Abstract

This study investigated the improvement of the electro-optical properties of a liquid crystal (LC) cell fabricated through brush coating using graphene oxide (GO) doping. The physical deformation of the surface was analyzed using atomic force microscopy. The size of the groove increased as the GO dopant concentration increased, but the direction of the groove along the brush direction was maintained. X-ray photoelectron spectroscopy analysis confirmed that the number of C–C and O–Sn bonds increased as the GO concentration increased. Since the van der Waals force on the surface increases as the number of O–metal bonds increases, we were able to determine why the anchoring energy of the LC alignment layer increased. This was confirmed by residual DC voltage and anchoring energy measurements that were later performed. As the GO concentration increased, the width of the hysteresis curve decreased, indicating that the residual DC voltage decreased. Additionally, the 15% GO-doped sample exhibited a significant increase in its anchoring energy up to 1.34 × 10−3 J/m2, which is similar to that of rubbed polyimide. It also secured a high level of electro-optical properties and demonstrated potential as a next-generation thin-film display despite being produced via a simple brush-coating process. [ABSTRACT FROM AUTHOR]

Published
2023
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27. Nano/microgroove zirconium‐doped lanthanum oxide film with self‐aligned molecules for liquid crystal device application.

Author

Choi, Bo‐Kyeong, Oh, Jin Young, Kim, Dae‐Hyun, Lee, Dong Wook, and Seo, Dae‐Shik

Subjects
LIQUID crystal films, SUBSTRATES (Materials science), LIQUID crystal devices, LANTHANUM oxide, ATOMIC force microscopy
Abstract

Herein, we propose a brush‐coated zirconium‐doped lanthanum oxide (ZrLaO) film as a liquid crystal (LC) alignment layer. The film‐curing temperature was adjusted to 70, 150, and 230°C. Polarized optical microscopy and pre‐tilt angle analysis confirmed that there was uniform and homogeneous LC alignment on the 230°C cured ZrLaO film. Atomic force microscopy revealed that the surface had a nano/microgroove structure, which was caused by the shear stress generated by the brush‐coating process. This structure induced the uniform LC alignment. X‐ray photoelectron spectroscopy verified that the ZrLaO film was well‐formed on a glass substrate. The ZrLaO film displayed hydrophilic characteristics, and its surface energy increased as the film‐curing temperature increased. The ZrLaO alignment layer displayed suitable optical transmittance for LC device applications. The ZrLaO layer‐based twisted‐nematic LC cell exhibited more stable switching properties and better threshold voltage characteristics than conventional polyimide layers. Therefore, we expect that this brush‐coated ZrLaO layer will be a suitable LC alignment layer for LC device applications. [ABSTRACT FROM AUTHOR]

Published
2024
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