Device for regulating the passage of light

1. A window which is suitable for regulating the passage of light in the form of daylight from the environment into a space, said window containing a switching device for regulating the passage of light between a bright state and a dark state which does not comprise a polariser, said switching device comprising a layer which comprises a liquid-crystalline material comprising at least three different dye compounds, where the liquid-crystalline material has a clearing point of at least 95° C. and comprises at least one compound V which contains at least one unit selected from units of the formulae (E-1), (E-2) and (E-3),

where

X is selected on each occurrence, identically or differently, from F, Cl, Br, I, —CN, —NCO, —NCS, —SCN, —OCN, —NC, —CNO, —CNS and N 3 ;

W is selected on each occurrence, identically or differently, from F, Cl, Br, I, —CN, —NCO, —NCS, —SCN, —OCN, —NC, —CNO, —CNS and N 3 ;

U is selected on each occurrence, identically or differently, from H, F, Cl, Br, I, CN, —NCO, —NCS, —SCN, —OCN, —NC, —CNO, —CNS, N 3 , and alkyl, alkoxy or alkylthio groups having 1 to 10 C atoms, where one or more hydrogen atoms in the alkyl, alkoxy or alkylthio groups may be replaced by F or Cl, and where one or more CH 2 groups in the alkyl, alkoxy or alkylthio groups may be replaced by O or S;

dashed lines symbolise bonds to the remainder of the compound,

and at least one group U per unit of the formula (E-3) is selected from F, Cl, Br, I, CN, —NCO, —NCS, —SCN, —OCN, —NC, —CNO, —CNS and N 3 ,

and wherein the liquid-crystalline material additionally comprises one or more compounds which conform to the formula (F-1-2)

R 11 , R 12 represent on each occurrence, identically or differently F, Cl, —CN, —NCS, —SCN, R 3 —O—CO—, R 3 —CO—O— or an alkyl or alkoxy group having 1 to 10 C atoms or an alkenyl or alkenyloxy group having 2 to 10 C atoms, where one or more hydrogen atoms in the above-mentioned groups may be replaced by F or Cl, and one or more CH 2 groups may be replaced by O or S.

2. A window according to claim 1 , wherein X is selected on each occurrence, identically or differently, from F and —CN.

3. A window according to claim 1 , wherein W is equal to —CN.

4. A window according to claim 1 , wherein U is selected on each occurrence, identically or differently, from H, F and —CN.

5. A window according to claim 1 , wherein the compound V contains precisely one unit selected from units of the formulae (E-1), (E-2) and (E-3).

6. A window according to claim 1 , wherein the compound V has a structure of the following formula:

where

R V1 , R V2 represent on each occurrence, identically or differently, an alkyl or alkoxy group having 1 to 10 C atoms or an alkenyl or alkenyloxy group having 2 to 10 C atoms, where one or more hydrogen atoms in the above-mentioned groups may be replaced by F or Cl, and one or more CH 2 groups may be replaced by O or S;

 is selected on each occurrence, identically or differently, from the following groups:

 or units of the formula (E-1), (E-2) or (E-3);

Y is selected on each occurrence, identically or differently, from F, Cl, CN, and alkyl, alkoxy or alkylthio groups having 1 to 10 C atoms, where one or more hydrogen atoms in the alkyl, alkoxy or alkylthio groups may be replaced by F or Cl, and where one or more CH 2 groups in the alkyl, alkoxy or alkylthio groups may be replaced by O or S;

n is equal to 1, 2 or 3; and

where at least one of the groups

is selected from units of the formula (E-1), (E-2) or (E-3).

7. A window according to claim 6 , wherein the compound of the formula (V) contains precisely one unit selected from units of the formulae (E-1), (E-2) and (E-3).

8. A window according to claim 6 , wherein the index n in formula (V) is equal to 1 or 2.

9. A window according to claim 6 , wherein A V1 in formula (V) is selected on each occurrence, identically or differently, from

and units of the formulae (E-1-1a), (E-1-2a), (E-1-3a), (E-2-1) and (E-3-1)

10. A window according to claim 1 , wherein the liquid-crystalline material has a clearing point of at least 100° C.

11. A window according to claim 1 , wherein the liquid-crystalline material has a dielectric anisotropy Δε of −2 to −10.

12. A window according to claim 1 , wherein the liquid-crystalline material comprises 5 to 15 compounds V, each having a different structure.

13. A window according to claim 1 , wherein the liquid-crystalline material has a total proportion of compounds V of at least 40% by weight.

14. A window according to claim 1 , wherein the liquid-crystalline material comprises compounds selected from compounds V which contain at least one unit of the formula (E-2), and compound(s) of the formula (F-1-2) in a total proportion of at least 10% by weight.

15. A window according to claim 1 , wherein the liquid-crystalline material additionally comprises one or more compounds which conform to the formula (F-2),

where

R 21 , R 22 represent on each occurrence, identically or differently, F, Cl, —CN, —NCS, —SCN, R 3 —O—CO—, R 3 —CO—O— or an alkyl or alkoxy group having 1 to 10 C atoms or an alkenyl or alkenyloxy group having 2 to 10 C atoms, where one or more hydrogen atoms in the above-mentioned groups may be replaced by F or Cl, and one or more CH 2 groups may be replaced by O or S; and

R 3 represents on each occurrence, identically or differently, an alkyl group having 1 to 10 C atoms, in which one or more hydrogen atoms may be replaced by F or Cl, and in which one or more CH 2 groups may be replaced by O or S;

Z 21 is selected on each occurrence, identically or differently, from —CO—O—, —O—CO—, —CF 2 —CF 2 —, —CF 2 —O—, —O—CF 2 —, —CH 2 —CH 2 —, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —C≡C—, —OCH 2 —, —CH 2 O— and a single bond; and

A 21 is selected on each occurrence, identically or differently, from the following groups:

where

Y is selected on each occurrence, identically or differently, from F, Cl, CN, and alkyl, alkoxy or alkylthio groups having 1 to 10 C atoms, where one or more hydrogen atoms in the alkyl, alkoxy or alkylthio groups may be replaced by F or Cl, and where one or more CH 2 groups in the alkyl, alkoxy or alkylthio groups may be replaced by O or S.

16. A window according to claim 1 , wherein the degree of anisotropy R of the dye compounds is greater than 0.4.

17. A window according to claim 1 , wherein the dye compounds are selected from azo compounds, anthraquinones, methine compounds, azomethine compounds, merocyanine compounds, naphthoquinones, tetrazines, perylenes, terrylenes, quaterrylenes, higher rylenes, benzothiadiazoles, pyrromethenes and diketopyrrolopyrroles.

18. A window according to claim 1 , which has an area extent of at least 0.5 m 2 .

19. A window according to claim 1 , where the device is electrically switchable.

20. A window according to claim 1 , where the device has the following layer sequence, where further layers may additionally be present:

substrate layer

electrically conductive transparent layer

alignment layer

switching layer comprising the liquid-crystalline material

alignment layer

electrically conductive transparent layer

substrate layer.

21. A method comprising the step of including a liquid-crystalline material comprising at least three different dye compounds in a window suitable for regulating the passage of light in the form of daylight from the environment into a space, said window containing a switching device for regulating the passage of light between a bright state and a dark state, which does not comprise a polariser, where the liquid-crystalline material is incorporated in a layer of said switching device and has a clearing point of at least 95° C. and comprises at least one compound V as defined in claim 1 which contains at least one unit selected from units of the formulae (E-1), (E-2) and (E-3), as defined in claim 1 .