Liquid-crystalline medium for use in a switching element

1. A window element, comprising a switching element, which switching element comprises a switching layer, which switching layer comprises a liquid-crystalline medium, wherein the switching layer is arranged between two substrates, and wherein the switching element is electrically switchable and operable in an optically transparent state and a scattering state, wherein the liquid-crystalline medium comprises

one or more mesogenic compounds of formula I

wherein

R 1 and R 2 denote, independently of one another, F, Cl, CF 3 , OCF 3 , a straight-chain alkyl or alkoxy having 1 to 15 carbon atoms, a branched alkyl or alkoxy having 3 to 15 carbon atoms, a straight-chain alkenyl having 2 to 15 carbon atoms, or a branched alkenyl having 3 to 15 carbon atoms, which is unsubstituted, monosubstituted by CN or CF 3 or mono- or polysubstituted by halogen and wherein one or more CH 2 groups may be, in each case independently of one another, replaced by —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another,

denotes

n denotes 0 or 1, and

denote, independently of one another,

wherein L is on each occurrence, identically or differently, halogen selected from the group consisting of F, Cl and Br,

and

one or more chiral compounds,

wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight, and

wherein the medium exhibits a clearing point of 98° C. or more.

2. The window element according to claim 1 ,

wherein the medium exhibits a pitch of 0.55 μm or more.

3. The window element according to claim 1 , in which the medium exhibits

an optical anisotropy Δn, determined at 20° C. and 589 nm, of 0.13 or more.

4. The window element according to claim 1 , in which the medium further comprises one or more mesogenic compounds of formulae II and/or III

wherein

R 3 , R 4 , R 5 and R 6 denote, independently of one another, F, CF 3 , OCF 3 , CN, a straight-chain alkyl or alkoxy having 1 to 15 carbon atoms, a branched alkyl or alkoxy having 3 to 15 carbon atoms, a straight-chain alkenyl having 2 to 15 carbon atoms or a branched alkenyl having 3 to 15 carbon atoms, which is unsubstituted, monosubstituted by CN or CF 3 or mono- or polysubstituted by halogen and wherein one or more CH 2 groups may be, in each case independently of one another, replaced by —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another, and

L 1 , L 2 , L 3 , L 4 and L 5 denote, independently of one another, H or F.

5. The window element according to claim 1 , wherein in the one or more mesogenic compounds of formula I L is F and R 1 and R 2 are not Cl.

6. The window element according to claim 1 , wherein the one or more chiral compounds in the medium have an absolute value of the helical twisting power of 5 μm −1 or more.

7. The window element according to claim 1 , wherein the medium further comprises one or more polymerisable compounds.

8. The window element according to claim 7 , wherein the one or more polymerisable compounds are contained in the medium in an amount, based on the overall contents of the medium, of 10% by weight or less.

9. The window element according to claim 7 , wherein one or more of the one or more polymerisable compounds comprise one, two or more acrylate and/or methacrylate groups.

10. The window element according to claim 7 , wherein one or more of the one or more polymerisable compounds are polymerisable mesogenic compounds.

11. The window element according to claim 1 , wherein the medium further comprises a polymeric component.

12. The window element according to claim 11 , wherein the polymeric component is contained in the medium in an amount, based on the overall contents of the medium, of 10% by weight or less.

13. A method for preparing the window element of claim 1 , therein a switching layer or a switching element, comprising

(a) providing the medium comprising the one or more mesogenic compounds of formula I and the one or more chiral compounds and which medium further comprises one more polymerisable compounds as a layer, and

(b) polymerising the one or more polymerisable compounds of said medium.

14. The window element according to claim 11 , wherein the polymeric component is obtained by polymerising one or more polymerisable compounds.

15. A cholesteric liquid crystal scattering device, comprising the window element according to claim 1 .

16. An automobile, comprising the window element according to claim 1 .

17. An architectural building, comprising the window element according to claim 1 .

18. A privacy window, comprising the window element according to claim 1 .