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.

An object of the present invention is to provide a composition that has positive , exhibits a liquid crystal phase over a wide temperature range, has low viscosity, excellent solubility at low temperatures, and high resistivity and voltage holding ratio, and is stable against heat and light. By using this composition, IPS or TN liquid crystal display devices and the like that have excellent display quality and suppress display failures such as image-sticking and drop marks are provided in high yield. Provided is a composition that contains at least one selected from the group consisting of compounds represented by general formulae (i) and (ii) and at least one compound represented by general formula (iii). Also provided is a liquid crystal display device that uses the composition and an IPS or FFS device that uses 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.

A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH,

##STR00001##

in which Z.sup.1 denotes a single bond, CH.sub.2CH.sub.2, CH?CH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, COO, OCO, C.sub.2F.sub.4, (CH.sub.2).sub.4, CHFCHF, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, C?C, CF?CF, CH?CHCHO or CH.sub.2CF.sub.2O,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

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 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.

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.

Shown are a liquid crystal composition having capability of achieving vertical alignment of liquid crystal molecules by action of a polymer, and a liquid crystal display device including the composition. A nematic liquid crystal composition has negative dielectric anisotropy and contains at least one polar compound selected from the group of compounds represented by formula (1) as a first additive, and the liquid crystal display device includes the composition. In formula (1), R.sup.1 is hydrogen, halogen, alkyl having 1 to 12 carbons or the like; R.sup.2 is a group represented by OH, OR.sup.0, NH.sub.2, NHR.sup.0 or N(R.sup.0).sub.2, in which R.sup.0 is alkyl having 1 to 5 carbons; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; Sp.sup.1 and Sp.sup.2 are independently a single bond, alkylene having 1 to 7 carbons or the like; and a is 0 to 4.

##STR00001##

A liquid-crystalline medium which comprises at least one compound of the formula I,

##STR00001## and one or more compounds of the formula ST

##STR00002## and to the use thereof for an active-matrix display, in particular based on the VA, PSA, PA-VA, SS-VA, SA-VA, PS-VA, PALC, IPS, PS-IPS, UB-FFS, U-IPS, FFS or PS-FFS effect.