Liquid crystal medium

A liquid crystal medium comprising

• a) one or more compounds of formula I
• in which
• R11 and R12 identically or differently, denote H, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy each having 3 to 15 C atoms, where one or more CH2 groups in these radicals may each be replaced, independently of one another, by
• —CH═CH—, —C≡C—, —CF2O—, —OCF2—, —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 may be replaced by halogen,
• L11 and L12 independently denote H, F, Cl, CH3, CF3 or CHF2;
• and
• b) one or more compounds selected from the group of compounds of formulae II and/or III
• in which
• R2 and R3,
• independently of one another, denote a straight-chain alkyl or alkoxy radical that is unsubstituted or halogenated and has 1 to 15 C atoms, or a branched alkyl or alkoxy radical that is unsubstituted or halogenated and has 3 to 15 C atoms, where one or more CH2 groups in these radicals may each be replaced, independently of one another, by
• —C≡C—, —CF2O—, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another,
• independently of one another denote
• L21, L22, L31 and L32
• independently of each other, denote H or F,
• Y2 and Y3 identically or differently, denote H or CH3,
• X2 and X3 independently of each other, denote halogen, halogenated alkyl or halogenated alkoxy with 1 to 3 C-atoms or halogenated alkenyl or halogenated alkenyloxy with 2 or 3 C-atoms,
• Z3 denotes —CH2CH2—, —CF2CF2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH2O— or a single bond, and
• l, m, n and o are, independently of each other, 0 or 1.