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 composition satisfying at least one of characteristics such as high maximum temperature of a nematic phase, low minimum temperature thereof, large optical anisotropy, large positive dielectric anisotropy and high stability to ultraviolet light, or having suitable balance regarding at least two of the characteristics; and a liquid crystal display device including such a composition and particularly including an encapsulated composition, and a liquid crystal display device serving as a constituent of a display device that allows switching of display between 2D and 3D. The liquid crystal composition contains a specific compound having large optical anisotropy as a first component and a specific compound having large positive dielectric anisotropy as a second component, and may further contain a specific compound having large optical anisotropy and further having high maximum temperature or low minimum temperature as a third component, and the liquid crystal display device includes the composition.

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.

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.

Provided is an LCD device having excellent high speed responsiveness. This LCD device contains a polymer or a copolymer in a liquid crystal composition sandwiched between two transparent substrates, at least one of which has an electrode, and the content of the polymer or the copolymer is 1% by mass or greater and less than 40% by mass of the total mass of the liquid crystal composition and the polymer or the copolymer. This LCD device can be applied to various operation modes such as TN, STN, ECB, VA, VA-TN, TPS, FFS, a cell, OCB, and cholesteric liquid crystals.

A liquid crystal composition includes one or more compounds represented by Chemical Formula 1:

##STR00001## wherein in Chemical Formula 1, A1, A2, L.sub.1 to L.sub.8, R, R, Z.sub.1 to Z.sub.3, n1, and n2 are the same as described in the specification.

To show a liquid crystal composition having at least one or a suitable balance regarding at least two of characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate; and an AM device having characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio and a long service life.

The liquid crystal composition has a negative dielectric anisotropy and contains a specific compound having a large negative dielectric anisotropy as a first component, and the composition may contain a specific compound having a high maximum temperature or a small viscosity as a second component, a specific compound having a large negative dielectric anisotropy as a third component, and a specific compound having a polymerizable group as an additive component.

The present invention relates to nematic liquid-crystal media of negative dielectric anisotropy which have a peak time (t.sub.max.) of 0.25 ms or less, which is determined as described in the disclosure, and which preferably have a value of the quotient of the peak time and the square of the birefringence (t.sub.max/n.sup.2) of 22 ms or less, and to the use of these liquid-crystal media in liquid-crystal displays, and to these liquid-crystal displays.

A solution is a compound represented by formula (1), a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

##STR00001##

In formula (1), R.sup.a and R.sup.b are independently alkyl having 1 to 30 carbons or the like; and X and Y are independently fluoroalkyl having 1 to 5 carbons, fluoroalkoxy having 1 to 5 carbons or pentafluorosulfanil, and one of X and Y may be fluorine.

The present invention relates to dielectrically positive liquid-crystalline media comprising one or more compounds of the formula I,

##STR00001##

and one or more compounds selected from the group of the compounds of the formulae II and III and/or IV,

##STR00002##

in which the parameters have the respective meanings indicated in the specification, and optionally one or more further dielectrically positive compounds and optionally one or more further dielectrically neutral compounds, and to liquid-crystal displays, especially active-matrix displays and in particular TN, IPS and FFS displays, containing these media.