The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (), which is distinguished by the fact that it has a value for the ratio .sub.1/n.sup.2 in the range 6-45 with a clearing point of >60 C. and a of 2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.

A liquid crystal display device having a liquid crystal composition, requiring neither an alignment film nor alignment treatment on a substrate. The problem is solved by a low molecular weight polar compound for homogeneously aligning a liquid crystal medium relative to the substrate, for example, the low molecular weight polar compound represented by formula (1).

Formula 95

M-P(1)

In formula (1), M is a nonpolar group having 1 or more carbons, and P is a polar group.

Provided is a liquid crystal composite that is suitable for dimming and includes a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a large optical anisotropy and a large negative dielectric anisotropy or being suitably balanced between at least two of these characteristics, and a liquid crystal dimming device including the liquid crystal composite, where the liquid crystal composite includes a polymer and a liquid crystal composition including a specific compound having a large negative dielectric anisotropy, and the liquid crystal composite may further include a specific compound having a high maximum temperature or a low minimum temperature.

The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I, ##STR00001## in which R.sup.1, R.sup.1*, Z.sup.1, Z.sup.2 and L.sup.1-3 have the meanings defined herein, and to the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, PS-IPS or IPS effect.

A liquid crystal composition that satisfies a plurality of characteristics in characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, small viscosity, large optical anisotropy, large dielectric anisotropy (1 kHz and 20 GHz), large specific resistance, high stability to ultraviolet light and high stability to heat, and that can be used in the form of a millimeter wave phase or microwave phase antenna.

The liquid crystal composition contains at least two specific compounds having the large optical anisotropy and the large dielectric anisotropy as a first component, and a specific compound having a wide nematic phase and capable of adjusting suitable optical anisotropy as a second component, and may contain such a component compound that can finely control the characteristics of the composition.

The subject is to show a liquid crystal composition in which the homeotropic alignment of liquid crystal molecules can be achieved by the action of a polymer, and a liquid crystal display device including this composition. The means concerns a nematic liquid crystal composition that has positive dielectric anisotropy and that includes a specific liquid crystal compound having a large positive dielectric anisotropy as a first component and a polar compound having a polymerizable group as a first additive, and the composition may include a specific liquid crystal compound having a high maximum temperature or a small viscosity as a second component, a specific liquid crystal compound having a positive dielectric anisotropy as a third component, a specific liquid crystal compound having negative dielectric anisotropy as a fourth component, and a polymerizable compound as a second additive, and concerns a liquid crystal display device including the composition.

A liquid crystal composition for dimming that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a large optical anisotropy and a large negative dielectric anisotropy, or that is suitably balanced between at least two of these characteristics, and a liquid crystal dimming device including this composition. A liquid crystal composition for dimming that includes a specific compound having a large negative dielectric anisotropy as a first component and that may include a specific compound having a high maximum temperature or a low minimum temperature as a second component.

The present invention relates to liquid crystalline media comprising one or more naphthothiadiazol derivatives of formula I,

##STR00001##

in which R.sup.11, R.sup.12, A.sup.11, A.sup.12, A.sup.21, A.sup.22, Z.sup.11, Z.sup.12, Z.sup.21, Z.sup.22, W, X.sup.11, X.sup.12, L, r, s and t have the meanings indicated in claim 1, to the use of such liquid crystal media for optical, electro-optical and electronic purposes, in particular in devices for regulating the passage of energy from an outside space into an inside space, for example in windows.

A liquid-crystalline medium having a nematic phase, a dielectric anisotropy of 0.5 or more and a ratio of the dielectric constant perpendicular to the director (?.sub.?) to the dielectric anisotropy (??), i.e. (?.sub.?/??), of 2.0 or less and comprises one or more compounds of formula I: ##STR00001##
wherein the parameters have the meaning given in the text. An electro-optical display containing such a medium, particularly in an active-matrix display based on the IPS or FFS effect. Methods for using of the compounds of formula I for improvement of the transmission and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

An object of the present invention is to provide a dye compound-containing liquid crystal composition that has high solubility and high solubility retention for the dye compound and has high light resistance and a device including the composition. The use of a combination of one or two or more predetermined alkenyl compounds and a compound including a predetermined difluoro structure can provide a dye compound-containing liquid crystal composition that has high solubility and high solubility retention for the dye compound and has high light resistance, and the dye compound-containing liquid crystal composition is useful for devices, in particular, photochromic devices.