Liquid-crystalline medium

A window element, comprising a switchable optical cell having a layer structure comprising in this order

• a first transparent substrate,
• a switchable layer, and
• a second transparent substrate,
• wherein the switchable layer comprises a liquid-crystalline medium having a negative dielectric anisotropy, a clearing point of 115° C. or more, and an optical anisotropy Δn of 0.10 or less.

A liquid-crystalline medium having a negative dielectric anisotropy, a clearing point of 115° C. or more, and an optical anisotropy Δn of 0.10 or less, comprising one or more compounds of formula IIA

• wherein
• R2A denotes 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, in addition, 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 denotes a single bond, —CH2CH2—, —CH═CH—, —CF2O—, —OCF2—, —CH2O—, —OCH2—, —COO—, —OCO—, —C2F4—, —CF═CF— or —CH═CHCH2O—,
• p denotes 0, 1 or 2, and
• v denotes 1 to 7.