Supertwisted nematic liquid crystal displays

A supertwist liquid-crystal display comprising:

• two plane-parallel outer plates which, together with a frame, form a cell,
• a liquid-crystal mixture of positive dielectric anisotropy which is present in the cell,
• electrode layers with superposed alignment layers on the insides of the outer plates which address each pixel by orthogonal row wave forms,
• pre-tilt angle between the longitudinal axis of the molecules at the surface of the outer plates and the outer plates of from about 1 degree to 30 degrees, and
• a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of between 22.5 and 600°, wherein the liquid-crystal mixture comprises
• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or tow non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F is Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1.
• wherein the liquid crystal mixture further comprises one or more compounds of formula V
• R is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, and
• Y2 is F or Cl.

A supertwist liquid-crystal display comprising:

• two plane-parallel outer plates which, together with a frame, form a cell,
• a liquid-crystal mixture of positive dielectric anisotropy which is present in the cell,
• electrode layers with superposed alignment layers on the insides of the outer plates which address each pixel by orthogonal row wave forms,
• pre-tilt angle between the longitudinal axis of the molecules at the surface of the outer plates and the outer plates of from about 1 degree to 30 degrees, and
• a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of between 22.5 and 600°, wherein the liquid-crystal mixture comprises
• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F or Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1;
• wherein the liquid crystal mixture comprises more than 58% by weight of one or more compounds having a positive dielectric anisotropy of more than +12.

A supertwist liquid-crystal display comprising:

• two plane-parallel outer plates which, together with a frame, form a cell,
• a liquid-crystal mixture of positive dielectric anisotropy which is present in the cell,
• electrode layers with superposed alignment layers on the insides of the outer plates which address each pixel by orthogonal row wave forms,
• pre-tilt angle between the longitudinal axis of the molecules at the surface of the outer plates and the outer plates of from about 1 degree to 30 degrees, and
• a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of between 22.5 and 600°, wherein the display has a threshold voltage of 1.5 V or less;
• wherein the liquid-crystal mixture comprises
• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F or Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1.

Liquid crystal mixture or composition, comprising:

• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F or Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1.

Liquid crystal mixture or composition, comprising:

• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the chiral nematic liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F or Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1;
• wherein the liquid crystal mixture further comprises one or more compounds of formula V
• R is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, and
• Y2 is F or Cl.

Liquid crystal mixture or composition, comprising:

• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF or a single bond,
• Y is F or Cl,
• L1 and L2 are each independently H or F, and
• m is 0 or 1;
• wherein the liquid crystal mixture comprises more than 58% by weight of one or more compounds having a positive dielectric anisotropy of more than +12.

Liquid crystal mixture or composition for a display having a threshold voltage of 1.5V or less comprising:

• a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5;
• b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from −1.5 to +1.5;
• c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than −1.5, and
• d) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the liquid-crystal mixture is from about 0.2 to 1.3,
• wherein the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I
• wherein
• R3 is an alkenyl group with 2 to 7 C atoms,
• R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Q—Y,
• Q is CF2, OCF2, CFH, OCHF, or a single bond,
• Y is F or Cl,
• L1 or L2 are each independently H or F, and
• m is 0 or 1.