A PSA-type liquid crystal composition includes a host liquid crystal A and a polymerizable component B, where the host liquid crystal A includes one or more liquid crystal compounds, and the polymerizable component B includes at least one compound selected from compounds of general formula I-1, general formula I-2 and general formula I-3. A liquid crystal display device includes the PSA-type liquid crystal composition above. The PSA-type liquid crystal composition has better intersolubility, cannot be crystallized at a low-temperature environment, can form a relatively stable pretilt angle after the polymerization of the polymerizable component, avoids the image sticking, and inhibits the occurrence of a display defect, such as Zara Particle, during the polymerization.

##STR00001##

Provided is a liquid crystal compound containing 2,3,4-trisubstituted benzene, a liquid crystal composition thereof, and a liquid crystal display element or a liquid crystal display comprising the liquid crystal compound or the liquid crystal composition, wherein the liquid crystal composition has a lower viscosity, can achieve a quick response, and further has a moderate dielectric anisotropy , a moderate optical anisotropy n, and high stability to heat and light. The liquid crystal display element or liquid crystal display comprising the liquid crystal composition has the properties of a wider nematic phase temperature range, an appropriate birefringence anisotropy, a very high electrical resistivity, a good ultraviolet resistant property, a high charge retention rate, a low vapor pressure etc., and particularly, the liquid crystal compound or the liquid crystal composition has the advantage of a high light transmittance.

Provided is a liquid crystal compound containing 2,3,4-trisubstituted benzene, a liquid crystal composition thereof, and a liquid crystal display element or a liquid crystal display comprising the liquid crystal compound or the liquid crystal composition, wherein the liquid crystal composition has a lower viscosity, can achieve a quick response, and further has a moderate dielectric anisotropy , a moderate optical anisotropy n, and high stability to heat and light. The liquid crystal display element or liquid crystal display comprising the liquid crystal composition has the properties of a wider nematic phase temperature range, an appropriate birefringence anisotropy, a very high electrical resistivity, a good ultraviolet resistant property, a high charge retention rate, a low vapor pressure etc., and particularly, the liquid crystal compound or the liquid crystal composition has the advantage of a high light transmittance.

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.

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.

Disclosed is a liquid crystal composition comprising one or more compounds represented by formula I, one or more compounds represented by formula II, and one or more compounds represented by formula III:

##STR00001##

The liquid crystal composition has simultaneously a lower rotary viscosity, a better photoelectric performance, a higher clearing point, a good low temperature performance, and less display defects. Further disclosed is a liquid crystal display element or device comprising the liquid crystal composition.

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.

Shown is a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a suitable optical anisotropy and a large dielectric anisotropy, or has a suitable balance regarding at least two of the characteristics, and an AM device including the composition. The liquid crystal composition contains a specific compound having large negative dielectric anisotropy as a first component, and a specific compound having small viscosity as a second component, and may contain a specific compound having negative dielectric anisotropy as a third component, a specific compound having a high maximum temperature or small viscosity as a fourth component or a specific compound having a polymerizable group as an additive component.

Disclosed is a liquid crystal composition and use thereof. The liquid crystal composition comprises components a, b and c; wherein component a is selected from one of the compounds represented by formula I; component b is a liquid crystal composition having a dielectric anisotropy of greater than 3; and component c is a liquid crystal composition having a dielectric anisotropy of 3 to 3. The liquid crystal composition has a high contrast ratio property, and has a low change rate at a low temperature, that is, the decrease of contrast ratio at a low temperature (such as 20 C.) is smaller as compared to a normal temperature. The composition has suitable properties with regard to practical applications, including a broader nematic phase range, an appropriate dielectric anisotropy, optical anisotropy and operating voltage, an excellent response time, a high electrical resistivity and voltage holding ratio, a low rotary viscosity, etc. ##STR00001##

The present invention discloses a liquid crystal composition comprising: 15-35% by weight of a compound of general formula I; 3-20% by weight of a compound of general formula II; 5-30% by weight of a compound of general formula III; 1-20% by weight of a compound of general formula IV; 10-35% by weight of a compound of general formula V-1 and/or a compound of general formula V-2; and 1-25% by weight of a compound of general formula VI. The liquid crystal composition provided by the present invention has the characteristics of an appropriate optical anisotropy, an appropriate dielectric anisotropy, a higher clearing point, a better voltage holding ratio, and a good UV-resistant stability, etc., and can be applied to a liquid crystal display. ##STR00001##