Liquid-crystal medium

1. A liquid-crystalline medium, comprising

one or more compounds of formula IA

in which

R 11 , R 12 identically or differently, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH 2 groups are optionally each replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH—CH—,

 —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen;

and

one or more compounds selected from the group of compounds of formulae T-1 to T-21

in which

R denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms,

(O) denotes —O— or a single bond,

m is 0, 1, 2, 3, 4, 5 or 6, and

n is 0, 1, 2, 3 or 4;

or

one or more polymerizable compounds of formula P

P-Sp-A 1 -(Z 1 -A 2 ) z -R  P

in which

P denotes a polymerisable group,

Sp denotes a spacer group or a single bond,

A 1 , A 2 each, independently, denotes an aromatic, heteroaromatic, alicyclic or heteroaliphatic group, which may contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L,

Z 1 denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, OCH 2 —, —CH 2 O—, —SCH 2 —, —CH 2 S—, —CF 2 O—, —OCF 2 —, —CF 2 S—, —SCF 2 —, —(CH 2 ) n1 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —(CF 2 ) n1 , —CH═CH—, —CF═CF—, —CH═CF—, —CF═CH—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH 2 —CH 2 —CO—O—, —O—CO—CH 2 —CH 2 —, —CR 0 R 00 —, or a single bond,

R 0 , R 00 identically or differently, denote H or alkyl having 1 to 12 C atom,

R denotes H, L, or P-Sp-,

L denotes F, Cl, —CN, P-Sp- or straight chain alkyl having 1 to 25 C atoms or a branched or cyclic alkyl having 3 to 25 C atoms, in which one or more non-adjacent CH 4 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and in which one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

z is 0, 1, 2 or 3, and

n1 is 1, 2, 3 or 4.

2. The medium according to claim 1 , wherein R 11 and R 12 , identically or differently, denote alkyl, alkenyl or alkoxy having 1 to 7 C atoms.

3. The medium according to claim 1 , wherein R 12 denotes alkoxy having 1 to 7 C atoms.

4. The medium according to claim 1 , wherein the total concentration of the one or more compounds of formula IA is 1% to 25% by weight.

5. The medium according to claim 1 , further comprising one or more compounds selected from the group of compounds of formulae IIA, IIB, IIC and IID,

in which

R 2A , R 2B , R 2C and R 2D each, independently of one another, denote H, an alkyl radical having 1 to 15 C atoms or alkenyl radical having 2 to 15 C atoms, which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,

 —C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another,

L 1 to L4 each, independently of one another, denote F or Cl,

Z 2 , Z 2B , and Z 2D each, independently of one another, denote a single bond, —CH 2 CH 2 —, —CH—CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —COO—, —OCO—, —C 2 F 4 —, —CF═CF—, or —CH═CHCH 2 O—,

(O) denotes —O— or a single bond,

p denotes 0, 1 or 2,

q denotes 0 or 1, and

v denotes 1 to 6.

6. The medium according to claim 1 , further comprising one or more compounds of formula IC

in which

R 11 and R 12 each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH 2 groups are optionally each replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—,

 —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen,

X 1 denotes S or O, and

L 11 and L 12 each, independently of one another, denote F, Cl, CF 3 or CHF 2 .

7. The medium according to claim 6 ,

wherein in formula IC

X 1 denotes S,

R 11 and R 12 each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, or an alkenyl radical having 2 to 15 C atoms and

L 11 and L 12 both denote F.

8. The liquid-crystalline medium according to claim 1 , further comprising one or more compounds selected from the group of compounds of formulae O-1 to O-18,

in which

R 1 and R 2 each, independently of one another, denote H, an alkyl radical having 1 to 15 C atoms or alkenyl radical having 2 to 15 C atoms, which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally replaced by —O—, —S—,

 —C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another.

9. The liquid-crystalline medium according to claim 1 , which comprises one or more compounds selected from the group of compounds of formulae T-1 to T-21,

in which

R denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms,

(O) denotes —O— or a single bond,

m is 0, 1, 2, 3, 4, 5 or 6, and

n is 0, 1, 2, 3 or 4.

10. The liquid-crystalline medium according to claim 1 , which comprises one or more polymerizable compounds of formula P

P-Sp-A 1 -(Z 1 -A 2 ) z -R  P

in which

P denotes a polymerisable group,

Sp denotes a spacer group or a single bond,

A 1 , A 2 each, independently, denotes an aromatic, heteroaromatic, alicyclic or heteroaliphatic group, which may contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L,

Z 1 denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—C—, —OCH 2 —, —CH 2 O—, —SCH 2 —, —CH 2 S—, —CF 2 O—, —OCF 2 —, —CF 2 S—, —SCF 2 —, —(CH 2 ) n1 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —(CF 2 ) n1 —, —CH═CH—, —CF═CF—, —CH═CF—, —CF═CH—, —C≡C—, —CH═CH—CO—C—, —O—CO—CH═CH—, —CH 2 —CH 2 —CO—O—, —O—CO—CH 2 —CH 2 —, —CR 0 R 00 —, or a single bond,

R 0 , R 00 identically or differently, denote H or alkyl having 1 to 12 C atoms,

R denotes H, L, or P-Sp-,

L denotes F, Cl, —CN, P-Sp- or straight chain alkyl having 1 to 25 C atoms or a branched or cyclic alkyl having 3 to 25 C atoms, in which one or more non-adjacent CH 2 -groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and in which one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

z is 0, 1, 2 or 3, and

n1 is 1, 2, 3 or 4.

11. The liquid-crystalline medium according to claim 10 , wherein the polymerisable compounds of formula P are polymerised.

12. The liquid-crystalline medium according to claim 10 , wherein a compound of formula IA is a compound of one of formulae IA-1 to IA-10:

in which R 12 denotes alkyl having 1 to 7 C-atoms.

13. A process of preparing an LC medium according to claim 1 , comprising mixing one or more compounds of formula IA with one or more compounds selected from the group of compounds of formulae T-1 to T-21 or with one or more polymerizable compounds of formula P and optionally with one or more additives.

14. A liquid-crystalline display comprising a medium according to claim 1 .

15. A liquid-crystalline display, which is a PSA display, comprising a liquid-crystalline medium that comprises one or more compounds of formula IA

in which

R 11 , R 12 identically or differently, denote H, an alky or alkoxy radical having 1 to 15 C atoms, in which one or more CH 2 groups are optionally each replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—,

 —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen.

16. The display according to claim 14 , which is a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN, polymer stabilised SA-VA, polymer stabilised SA-FFS display, VA IPS, U-IPS, FFS, UB-FFS, SA-FFS or SA-VA display.

17. The PSA display according to claim 15 , wherein, in a compound of formula IA,

R 11 and R 12 identically or differently, denote alkyl, alkenyl or alkoxy having 1 to 7 C atoms.

18. The liquid-crystalline medium according to claim 12 , wherein R 12 denotes ethyl, n-propyl or n-butyl.

19. The liquid-crystalline medium according to claim 12 , wherein a compound of formula IA is a compound of one of formulae IA-1 to IA-6.

20. The liquid-crystalline medium according to claim 12 , wherein a compound of formula IA is a compound of one of formulae IA-7 to IA-10.