Liquid crystal composition and liquid crystal display device having same

A liquid crystal composition comprising:

• at least one compound of general formula I
• at least one compound of general formula II
• and
• at least one compound of general formula III
• in which:
• R1 and R2 each independently represents —H, —F, C1-12 linear alkyl or alkoxy, C2-12 alkenyl or alkenoxy, or —OR1′OR2′, wherein one or more H of the alkyl or alkoxy and the alkenyl or alkenoxy can be substituted by F, wherein R1′ represents C3-12 alkylene or C3-12 alkenylene, R2′ represents linear C1-12 alkyl or C2-12 alkenyl;
• R3 and R4 each independently represents —H, —F, C1-12 linear alkyl or alkoxy, C2-12 alkenyl or alkenoxy, or —OR3′OR4′, wherein one or more H of the alkyl or alkoxy and the alkenyl or alkenoxy can be substituted by F, wherein R3′ represents C3-12 alkylene or C3-12 alkenylene, R4′ represents linear C1-12 alkyl or C2-12 alkenyl;
• R5 and R6 each independently represents —H, —F, C1-12 linear alkyl or alkoxy, C3-6 cycloalkyl, or C2-12 alkenyl or alkenoxy;
• Z1 represents single bond;
• Z2, Z3 and Z4 each independently represents single bond, —COO—, —OCO—, —CH2O—, —OCH2— or —CH2CH2—;
• L1 and L2 each independently represents —H, —F, —Cl, —CN or —NCS;
• L3 and L4 each independently represents —F, —Cl, —CN or —NCS;
• ring
• represents
• wherein one or more —CH2— in
• can be replaced by —O—, one or more H on
• can be substituted by halogen;
• ring
• ring
• ring
• and ring
• each independently represents
• a represents 0, 1, 2 or 3, when a is 2 or 3, ring
• can be same or different, with at least one ring
• represents
• b, c, and d each independently represents 0 or 1;
• wherein at least one of R1 or R2 is —OR1′OR2′ or at least one of R3 or R4 is —OR3′OR4′.