Browsing by Author "Fuh, Andy Ying-Guey"

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Derivation of extended Maxwell Garnett formula for carbon-nanotube-doped nematic liquid crystal
(2013-06-01)
Fuh, Andy Ying-Guey
;
Lee, Wei
;
Huang, Kevin Yu-Chia
;
光電學院
;
College of Photonics
A numerical effort for modelling the dielectric behaviour of the novel binary mixture of nematic liquid crystal and carbon nanotube (NLC:CNT) has been carried out using the Maxwell Garnett theory. The CNTs are treated as conductive anisotropic inclusions while the NLCs as dielectric isotropic or anisotropic matrix depending on temperature. Thus, the numerical expressions for the dielectric anisotropy for the scenarios of aligned CNTs in the NLC matrix of either nematic or isotropic phases have been derived, and the results show that the Debye parameter of CNT at optic limit seems to be the decisive factor in the enhancement of the dielectric anisotropy of the nematic system.
Liquid-Crystal-Carbon-Nanotube Composite: A Chemophysical Point of View
(2014)
Fuh, Andy Ying-Guey
;
Lee, Wei
;
Huang, Kevin Yu-Chia
;
光電學院
;
College of Photonics
This paper aims to provide insight into the chemophysical nature of the composite of liquid crystal (LC) and carbon nanotube (CNT). A dilute colloid of CNT dispersed in a nematic was prepared for dielectric and birefringence measurements. Molecular dynamics calculations revealed that the polarizability anisotropy of CNT, which induces anisotropic dipolar moments when the composite is subjected to an electric field, plays an important role in enhancing the dielectric anisotropy of the nematic host. Based on the results, field-activated LC materials containing tiny amounts of CNT are expectable for potential applications in LC devices.
Variable liquid crystal pretilt angles generated by photoalignment in homeotropically aligned azo dye-doped liquid crystals
(2009-10-19)
Fuh, Andy Ying-Guey
;
Liu, Cheng-Kai
;
Cheng, Ko-Ting
;
Ting, Chi-Lung
;
Chen, Che-Chang
This letter demonstrates the feasibility of producing variable liquid crystal (LC) pretilt angles using light-induced ripple structures (LIRSs) in homeotropically aligned azo dye-doped liquid crystals (ADDLCs). Illuminating homeotropically aligned ADDLCs with a linearly polarized light for a suitable period yields the LIRSs which provide LCs an anisotropic homogeneous anchoring force. Experimentally, the effective alignment force produced by the homeotropic alignment layer and the LIRSs determines the LC pretilt angle (24 degrees to 63.5 degrees), defined from the normal to the substrate. A no-bias pi cell for liquid crystal displays is demonstrated using this approach. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3253413]