Liquid crystal medium and liquid crystal device

Medium comprising at least 60% of two or more compounds of formula I

• wherein
• R11 and R12 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms, which may be unsubstituted, mono- or polysubstituted by halogen or CN, where one or more non-adjacent CH2 groups may to be replaced, in each occurrence independently from one another, by —O—, —S—, —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —O—CO—O—, —S—CO—, —CO—S—, —CH═CH—, —CH═CF—, —CF═CF— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another,
• at least one of
• R11 and R12 is an alkyl group, i.e. a straight-chain or branched alkyl group with 1 to 25 C atoms, which may be unsubstituted, mono- or polysubstituted by halogen or CN, where one or more non-adjacent CH2 groups may be replaced, in each occurrence independently from one another, by —O—, —S—, —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —O—CO—O—, —S—CO—, —CO—S—, —CH═CH—, —CH═CF—, —CF═CF— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another in which one CH2 groups is replaced by —CH═CH—, —CH═CF—, —CF═CF—, but from which OCF3 and CF3, are excluded,
• MG11 and MG12 are each independently a mesogenic group, wherein at least one of MG11 and MG12 comprises one, two or more 5-atomic and/or 6-atomic rings, in case of comprising two or more 5- and/or 6-atomic rings at least two of these may be linked by a 2-atomic linking group,
• Sp1 is a spacer group comprising 1, 3 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH2 groups may also be replaced by —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O—, —CH(halogen)-, —CH(CN)—, —CH═CH— or —C≡—, however in such a way that no two O-atoms are adjacent to one another, no two —CH═CH— groups are adjacent to each other and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other, and
• X11 and X12 are independently from one another a linking group selected from —CO—O—, —O—CO—, —O—, —CH═CH—, —C≡C—, —CF2—O—, —O—CF2—, —CF2—CF2, —CH2—O—, —O—CH2—, —CO—S—, —S—CO—, —CS—S—, —S—, and a single bond, under the condition that in —X11-Sp1-X12— no two O atoms are adjacent to one another, no two —CH═CH— groups are adjacent to each other and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other.