Liquid-crystal medium

A liquid crystal medium comprising

• a) one or more compounds of the formula I:
• in which
• R1 and R2, 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 or alkenyloxy having 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—, —OCF2—, —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 may each be replaced by halogen,
• Z1 denotes —CF2O—, —OCF2—, —CH2O—, —OCH2—, —CO—O—, —O—CO—, —C2H4—, —CH═CH—, —C═C— or a single bond,
• L1 and L2, each, independently of one another, denote F, Cl, CF3 or CHF2,
• Y denotes H, F, Cl, CF3, CHF2 or CH3;
• b) one or more compounds selected from the group of compounds of formulae IID-7
• in which alkyl on each occurrence, identically or differently, denotes a straight-chain alkyl radical having 1-6 C atoms, and
• (O) denotes O or a single bond;
• and
• c) one or more compounds selected from the group of compounds of III-2-1, III-2-2, III-2-3, III-2-4, III-2-5, III-2-6, III-2-7, III-2-8, III-2-9, and III-2-10, and one or more compounds selected from the group of compounds of formulae III-3-1, III-3-2, III-3-4, III-3-5, and III-3-6
• in which
• alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms,
• alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6° C. atoms,
• alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms,
• R32 denotes ethyl, n-propyl, or n-butyl, and
• L31 and L32 each, independently of one another, denote F, Cl, CF3 or CHF2;
• wherein the medium has a negative dielectric anisotropy.