Liquid-crystal medium

A liquid crystal medium comprising

• a) one or more compounds of the formula I
• in which
• Ar denotes a methylene group or an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms;
• Sp denotes a spacer group;
• RS denotes H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms;
• ZS denotes —O—, —C(O)O—, —(CH2)z— or —(CH2)zO—, or a single bond;
• HA denotes
• RH denotes H, O•, CH3, OH or ORS;
• RS1, RS2, RS3 and RS4, identically or differently, denote alkyl having 1 to 6 C atoms;
• G denotes H or RS or a group ZS-HA;
• z is an integer from 1 to 6, and
• q is 2, 3 or 4;
• and
• b) one or more compounds selected from the group of compounds of the formulae IIA, IIB, IIC, and
• c) in addition, one or more compounds of the formula IID:
• in which
• R2A, R2B, R2C and R2D each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where one or more CH2 groups in these radicals may each be replaced by —O—, —S—,
• —C≡C—, —CF2O—, —OCF2—, —OC—O—, or —O—CO— in such a way that O atoms are not linked directly to one another;
• L1 and L2 each, independently of one another, denote F, Cl, CF3 or CHF2;
• Y denotes H, F, Cl, CF3, CHF2, or CH3;
• Z2, Z2B and Z2D each, independently of one another, denote a single bond, —CH2CH2—, —CH═CH—, —CF2O—, —OCF2—, —CH2O—, —OCH2—, —COO—, —OCO—, —C2F4—, —CF═CF—, or —CH═CHCH2O—;
• (O) denotes O or a single bond;
• p denotes 0, 1 or 2;
• q denotes 0 or 1;
• and
• v denotes 1, 2, 3, 4, 5, or 6;
• wherein
• (i) the one or more compounds of formula IID includes at least one compound of the formula IID-10 or
• (ii) the medium further comprises at least one compound of the formula CL:
• in which
• R2D and (O) have the meanings defined for formula IID, and alkyl denotes n-alkyl having 1 to 5 C atoms,
• RL denotes H, a straight chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, or a straight chain or branched alkenyl radical having 2 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, in addition, one or more H atoms may each be replaced by halogen,
• XL denotes F, Cl, CN, CHF2, CF3, OCF3, or, identically or differently, has one of the meanings of RL, and
• YL denotes H, F, Cl or CH3.