Liquid-crystalline medium

A TN or STN liquid crystal display comprising

• two substrates which, together with an edging, form a cell,
• contained in the cell, a nematic liquid crystal mixture with positive dielectric anisotropy,
• electrode layers having alignment layers on the insides of the substrates,
• a pre-tilt angle between the longitudinal axis of the molecules at the surface of the substrates and the substrates of 0 to 30 degrees,
• a liquid crystal mixture in the cell with a twist angle from alignment layer to alignment layer of 22.5° to 600°, and
• a nematic liquid crystal mixture comprising
• a) 15-75 wt % of a liquid-crystalline component A, containing one or more compounds with a dielectric anisotropy of more than +1.5;
• b) 25-85 wt % of a liquid-crystalline component B, containing one or more compounds with a dielectric anisotropy of −1.5 to +1.5;
• c) 0-20 wt % of a liquid-crystalline component D, containing one or more compounds with a dielectric anisotropy of less than −1.5, and
• d) optionally an optically active component C in an amount that the ratio between layer thickness, spacing of the substrates, and natural pitch of the chiral nematic liquid crystal mixture is 0.2 to 1.3,
• wherein component A comprises at least one compound of formula A
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• and component B comprises at least one compound of formula B
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• wherein
• Ra, Rb and Rbb are each, independently of one another, an alkyl radical of 1 to 12 C atoms which is unsubstituted, singly substituted by CN or CF3 or at least singly substituted by halogen, wherein optionally one or more CH2 groups in the radical is, in each case independently, replaced by —O—, —S—,
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• —CH═CH—, —C≡C—, —CO—, —CO—O—, —O—CO— or —O—CO—O— such that O atoms are not directly linked together,
• L1 is H or F,
• Q is CF2, OCF2, CFH, OCFH or a single bond,
• Y is F or Cl, and
• Q—Y together is optionally NCS, SCN, OCHFCF3 or SF5.