The present invention relates to liquid-crystalline media (LC media) having negative or positive dielectric anisotropy, comprising a low-molecular-weight component and a polymerizable component. The polymerizable component comprises self-aligning, polymerizable mesogens (polymerizable self-alignment additives) which effect homeotropic (vertical) alignment of the LC media at a surface or the cell walls of a liquid-crystal display (LC display). The invention therefore also encompasses LC displays having homeotropic alignment of the LC medium without alignment layers. The invention discloses novel structures for self-alignment additives which have a certain position of the functional groups.

The liquid crystal composition of the present invention can be used in a liquid crystal display element of an IPS type or a TN type in which display defects such as burn-in and dropping marks in high speed response are unlikely to be generated. Since the liquid crystal composition contains a component which is a dielectrically positive component including a dielectrically positive compound and a dielectrically neutral component of which dielectric anisotropy is greater than −2 and less than +2, the liquid crystal composition has excellent characteristics that the liquid crystal composition has a liquid crystal phase in a wide temperature range, low viscosity, excellent solubility at a low temperature, high specific resistance and a high voltage holding ratio, and is stable with respect to heat and light.

The present invention discloses a compound of which a structural formula thereof is represented as the following formula: ##STR00001##
The compound disclosed by the present invention can be used as a liquid crystal compound and overcomes the problem that solubility of the traditional dibenzothiophene-class liquid crystals is poor, and thus can be better applied to the liquid crystal material field. The present invention further discloses a liquid crystal medium containing the compound and an application thereof.

A liquid-crystalline medium containing one or more compounds of formula IA, ##STR00001##
and the use thereof in an active-matrix display, in particular in a VA, IPS, U-IPS, FFS, UB-FFS, SA-VA, SA-FFS, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN, polymer stabilised SA-VA or polymer stabilised SA-FFS display.

Disclosed are a liquid crystal composition and a liquid crystal display device. The liquid crystal composition comprises at least one compound of general formula I, at least one compound of general formula II, at least one compound of general formula III, and at least one compound of general formula IV. By compounding the four compounds, the composition can have advantages of a wide temperature range of nematic phase, a low viscosity and a low threshold voltage, and the liquid crystal display element can have a short response time and great power saving performance.

A liquid crystal composition includes at least one compound of general Formula I, at least one compound of general Formula II and at least one compound of general Formula M. The polymerizable liquid crystal composition provides a higher VHR (especially an excellent VHR after UV irradiation), a lower surface roughness of the polymer layer, a faster polymerization rate, a lower residual amount of the polymerizable compound and a better pretilt angle stability, which enables the production of a liquid crystal display device with a better voltage stability and a faster response speed, and can effectively reduce or prevent the occurrences of problems such as “burn-in”, “image sticking”, “Zara Particle” and “uneven display” in the liquid crystal display device. A liquid crystal display includes the liquid crystal composition. ##STR00001##

A liquid crystal composition and a liquid crystal display device including the liquid crystal composition include at least one compound of general formula I and at least one compound of general formula II. Compared with the prior art, the liquid crystal composition has a smaller voltage change rate at high and low temperatures and a shorter low temperature response time, while maintaining an appropriate optical anisotropy, an appropriate clearing point, an appropriate absolute value of dielectric anisotropy, such that the liquid crystal display device having the liquid crystal composition has a better display and a faster response speed.

##STR00001##

There are provided a liquid crystal composition containing one or two or more compounds represented by general formula (L) and three or four or more dichroic dyes selected from azo compounds, and a guest-host liquid crystal display device or light-controlling device that uses the liquid crystal composition. The liquid crystal composition according to the present invention contains dichroic dyes that satisfy high contrast, high solubility, high nematic-isotropic transition temperature (T.sub.NI), and low birefringent anisotropy (Δn) effective for high light resistance and high thermal resistance at the same time. The use of the liquid crystal composition according to the present invention provides a liquid crystal display device or a light-controlling device that exhibits a good-looking black color and has high contrast, high display quality, and high practicality.

Provided are a liquid crystal composition containing a dibenzo derivative and a liquid crystal display device. The liquid crystal composition includes at least one compound of general formula I and at least one compound of general formula II. The liquid crystal compositions have the characteristics of high clearing point, large optical anisotropy, large dielectric anisotropy, large ε.sub.⊥, large ε.sub.⊥/|Δε|, and large K.sub.ave. The liquid crystal display devices containing these liquid crystal compositions have the effects of good transmittance and high contrast. The liquid crystal composition can meet the requirements of the liquid crystal display device on low power consumption and good display effect and has high application value in liquid crystal displays of in-plane switching (IPS) mode, fringe field switching (FFS) mode, and vertical alignment (VA) mode.

##STR00001##

The present invention relates to liquid-crystal (LC) media as defined in claim 1, having negative dielectric anisotropy and to the use thereof for optical, electro-optical and electronic purposes, in particular in LC displays.