The properties of liquid crystal (LCs) can be altered by incorporating guest materials. The physical properties of carbon nano tubes doped liquid crystal (CNTs/LC) and pristine LC have been investigated. The rotational viscosity of CNTs/LC was lower whereas dielectric anisotropy was almost the same as compared to pristine LC. Also the twisted nematic LC cell driven by vertical field and homogeneously aligned nematic LC cells doped with carbon nanotubes (CNTs) driven by an in-plane field were fabricated and their electro-optic characteristics were investigated. The response time of CNTs doped LC was found to be improved due to the decrease in rotational viscosity.
Recently, active researches on carbon Nanotube (CNT)-doped liquid crystal (LC) mixtures are progressing. Based on
experimental observations, CNTs are known to align parallel to the LC director and experience orientational deformation
associated with the LC deformation under an electric field. Theoretical calculation also shows that the LC is strongly
anchored on CNT in a way that the LC director is parallel to the CNT long axis. Many experimental results have been
reported regarding to CNT effects on electro-optic characteristics of the LC device such as threshold voltage, residual dc and
response time, and physical properties of a nematic LC such as rotational viscosity, dielectric anisotropy, elastic constants
and clearing temperature, although some are still controversial. In this talk, historical reviews as well as our achievements on
CNT-LC mixtures will be discussed.
The Vertically Aligned (VA) technology is one of the newer modes of operation among TFT displays. For VA displays, the liquid crystal is aligned homeotropically and possess a negative dielectric anisotropy (De<0) in order to switch perpendicular to an applied electric field. A new generation of nematic LC materials has been developed which reduces rotational viscosity (g1) but keeps other important parameters unchanged. The switching time parameter, g1/Dn2, is compared with those of previous reference mixtures possessing a range of optical anisotropies. The results show that the new mixtures give a consistent reduction in g1/Dn2 for a wide spread of Dn. Reduction in threshold voltage (V0) is an important goal for the majority of applications and can be achieved by increasing the absolute magnitude of (formula available in paper). However this in turn increases rotational viscosity (g1). The new mixtures overcome this drawback and significantly decrease the values of g1/Dn2 over a wide range of V0. A requirement for TV displays is increased brightness. The result is an increased operating temperature and therefore, higher clearing temperatures of the LC mixtures are demanded, but they lead to higher g1. The new LC components were successful in reducing g1/Dn2 in comparison with the previous standards for a range of clearing points.
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