Open Access Nano Express

Zenithal alignment of liquid crystal on homeotropic polyimide film irradiated by ion beam

Yoonseuk Choi1, Tae-Hoon Yoon2, Jin Hyuk Kwon3, Jonghoon Yi3 and Jin Seog Gwag3*

Author Affiliations

1 Department of Electronics, Hanbat National University, Daejeon, 305-719, South Korea

2 Department of Electronics Engineering, Pusan National University, Pusan, 609-735, South Korea

3 Department of Physics, Yeungnam University, 214-1 Dae-dong, Gyeongsan 712-749, South Korea

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Nanoscale Research Letters 2012, 7:63  doi:10.1186/1556-276X-7-63

Published: 5 January 2012

Abstract

We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality.