Browsing by Author "Liu, Shih-Hsien"

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LC mixture with promoted electro-optical properties for LCD applications by using a highly UV-resistant dopant
(2015-04-01)
Liu, Shih-Hsien
;
Yang, Po-Jen
;
Lin, Hong-Cheu
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A highly ultraviolet (UV)-resistant dopant 3HBBTfV consisting of an alpha-trifluomethyl vinylbenzene (TfV) moiety was synthesized and mixed with a commercial LC host (A) to promote its dielectric anisotropy in LC mixture C (A:3HBBTfV = 9:1 w/w). Their electric-optical properties were studied and compared with those of an analogous commercial LC mixture B composed of LC mixture A (as a commercial host) mixed with the same weight ratio (10% wt.) of a commercial component 3HBEBTf containing a 3,4,5-trifluorobenzene (BTf) moiety. The electro-optical properties of voltage holding ratio (VHR) values and voltage-transmission (V-T) curves of LC mixture C were sustained after the UV irradiation. These results showed that dopant 3HBBTfV (acting as an UV stabilizer) demonstrated a higher stability under UV exposure in contrast to commercial component 3HBEBTf. Therefore, LC mixture C (containing UV-resistant dopant 3HBBTfV) exhibited good UV resistance, high dielectric anisotropy, and excellent electro-optical properties. (C) 2015 Optical Society of America
Synthesis and study of hybrid hydrogen-bonded bent-core liquid crystal complexes containing C-60- and Si-based proton donors
(2015-01-01)
Liu, Shih-Hsien
;
Yang, Po-Jen
;
Wei, Chong-Lun
;
Chiang, I. -Hung
;
Liao, Chun-Yen
Novel hydrogen-bonded (H-bonded) C-60- and Si-based bent-core liquid crystal (LC) complexes containing a bent-shaped proton acceptor and C-60- and Si-based single/double armed proton donors were synthesized and mixed to produce hybrid H-bonded LC complexes. The SmCP phases could be introduced in the hybrid LC complexes with a very high C-60-based moiety up to 90 mol%. Among our H-bonded LC complexes, the hybrid LC complexes with low amounts of the C-60-based moiety (<= 24 mol%) possessed the highest spontaneous polarization value (ca. 494 nC cm(-2)), the widest mesophasic range (40.8 degrees C) and the lowest saturated electric field (8.8 V-pp mu m(-1)). Under electric fields of modified triangle waveforms, both series of hybrid H-bonded LC complexes displayed an anti-ferroelectric (AF) to a ferroelectric (FE) polar switching as the C-60-based moiety increased up to 24-50 mol%. Therefore, the hybrid H-bonded LC complexes containing a broad molar ratio (0-90 mol%) of C-60-based moiety revealed a tunable route for the electro-optical applications of C-60-based H-bonded liquid crystals.