Patent ID: 7553522

Claim:
A liquid-crystalline medium having a nematic phase wherein the liquid-crystalline medium has a dielectric relaxation frequency of more than 200 kHz at a temperature of 0°C., and wherein the liquid crystalline medium comprises at least one strongly polar two-ring substance selected from the group of compounds of the formula (Ia) and additionally optionally comprises one or more strongly polar two-ring substances of the formula (Ib): in which: —L 1 , L 2 , L 3 and L 4 each denote, independently from one another, hydrogen or fluorine, provided that at least one of L 1 , L 2 , L 3 and L 4 is fluorine: —R 1 denotes: hydrogen, halogen, an alkyl or alkoxy group with 1 to 7 carbon atom(s), or an alkenyl, alkenyloxy, alkinyl or alkinoxy group with 1 to 7 carbon atoms, wherein for all mentioned groups of R 1, one or more —CH 2 — groups are optionally replaced by —O—, >C=O or —S— with the proviso that no two oxygen atoms are adjacent and wherein the R 1 mentioned groups are also optionally substituted by halogen: —X 1 denotes: halogen, a fluorinated alkyl or alkoxy group with 1 to 5 carbon atom(s), a fluorinated alkenyl, alkenyloxy or oxyalkyl group with 2 to 4 carbon atom(s), —OCF 3, —OCHFCF 3 or —SF 5 ; and —Z denotes: a single bond, —CF 2 O—, —COO—or OCF 2 —, —CH 2 CH 2 —, —CH=CH—, —C≡C—, —OCO—, —CH 2 O—, —(CH 2 ) 4 —, —CF=CF—, —CH=CF— or —CF=CH—.