Liquid crystal composition and display device including the same

1. A liquid crystal composition comprising a compound having a structure represented by formula A-1:

wherein

R A1 is an alkyl group, an alkoxy group, a cyano group, a halogen atom, or a hydrogen atom, R A2 is an alkyl group, a cyano group, a halogen atom, or a hydrogen atom, Z A is *—O—*, *—COO—*, *—OCO—*, *—CF 2 O—*, *—OCF 2 —*, *—CH 2 O—*, *—OCH 2 —*, *—SCH 2 —*, *—CH 2 S—*, *—C 2 F 4 —*, *—CH 2 CF 2 —*, *—CF 2 CH 2 —*, *—(CH 2 ) k —*, *—CH═CH—*, *—CF═CF—*, *—CH═CF—*, *—CF═CH—*, *—CH═CHCH 2 O—*, or a single bond, X is a halogen atom, each of l1 and l2 is independently an integer of 0 to 2, and when l1 is 2

and Z A in a repeating unit defined by l1 are the same or different, k is an integer of 1 to 5, and “*” indicates a point of attachment.

2. The liquid crystal composition of claim 1 , wherein the compound having the structure represented by formula A-1 is a compound having a structure represented by formula A-2:

wherein

R A1 is an alkyl group having a carbon number of 1 to 5, an alkoxy group having a carbon number of 1 to 5, a cyano group, a halogen atom, or a hydrogen atom, R A2 is an alkyl group having a carbon number of 1 to 5, a cyano group, a halogen atom, or a hydrogen atom, and Z A , X, l1, and l2 are the same as those in formula A-1.

3. The liquid crystal composition of claim 2 , wherein the compound having the structure represented by formula A-2 is a compound having a structure represented by formula A-3, formula A-4, or formula A-5:

wherein each of

is independently

each of Z A1 and Z A2 is independently *—O—*, *—COO—*, *—OCO—*, *—CF 2 O—*, *—OCF 2 —*, *—CH 2 O—*, *—OCH 2 —*, *—SCH 2 —*, *—CH 2 S—*, *—C 2 F 4 —*, *—CH 2 CF 2 —*, *—CF 2 CH 2 —*, *—(CH 2 ) k —*, *—CH═CH—*, *—CF═CF—*, *—CH═CF—*, *—CF═CH—*, *—C≡C—*, *—CH═CHCH 2 O—*, or a single bond, R A1 , R A2 , X, and l2 are the same as those in formula A-2, and k is an integer of 1 to 5.

4. The liquid crystal composition of claim 3 , wherein the compound having the structure represented by formula A-3, formula A-4, or formula A-5 is a compound having a structure represented by any one of formulas A-6 to A-13:

5. The liquid crystal composition of claim 4 , comprising one or more of the compounds having the structures represented by formulas A-6 to A-13.

6. The liquid crystal composition of claim 4 , wherein the compound having the structure represented by any one of formulas A-6 to A-13 has a refractive index anisotropy of about 0.230 to about 0.260 and a rotational viscosity at 20° C. of about 70 to about 100 millipascal-seconds.

7. The liquid crystal composition of claim 4 , wherein the liquid crystal composition has a refractive index anisotropy of about 0.080 to about 0.120, a dielectric anisotropy of about −5.5 to about −2.8, and a rotational viscosity at 20° C. of about 70 to about 110 millipascal-seconds.

8. The liquid crystal composition of claim 1 , further comprising a compound having a structure represented by formula B-1:

wherein each of

is independently

R B1 is an alkyl group, an alkoxy group, or a hydrogen atom, R B2 is an alkyl group, an alkoxy group, an acetamide group, a hydroxyl group, or a hydrogen atom, each of Z B1 , Z B2 , and Z B3 is independently alkylene group having a carbon number of 1 to 5, an alkenylene group having a carbon number of 2 to 3, *—O—*, *—COO—*, *—OCO—*, *—CF 2 O—*, *—OCF 2 —*, a single bond, or a double bond, and each of m1 and m2 is independently 0 or 1.

9. The liquid crystal composition of claim 8 , wherein the compound having the structure represented by formula B-1 is a compound having a structure represented by formula B-2:

wherein each of

is independently

R B1 is an alkyl group having a carbon number of 1 to 5, an alkoxy group having a carbon number of 1 to 5, or a hydrogen atom, R B2 is an alkyl group having a carbon number of 1 to 4, an alkoxy group having a carbon number of 1 to 4, an acetamide group, a hydroxyl group or a hydrogen atom, and Z B1 , Z B2 , Z B3 , m1, and m2 are the same as those in formula B-1.

10. The liquid crystal composition of claim 9 , wherein the compound having the structure represented by formula B-2 is a compound having a structure represented by formula B-3, formula B-4, or formula B-5:

wherein

R B1 , R B2 , Z B1 , Z B2 , and Z B3 are the same as those in formula B-2.

11. The liquid crystal composition of claim 10 , wherein the compound having the structure represented by formula B-3, formula B-4, or formula B-5 is a compound having a structure represented by any one of formulas B-6 to B-9:

12. The liquid crystal composition of claim 8 , further comprising a compound having a structure represented by formula C-1:

wherein each of R C1 and R C2 is independently

Z C is an alkylene group, an alkyleneoxy group, an ether group, or a single bond, X is a halogen atom, n1 is an integer of 2 to 4, each of n2 and n3 is independently 0 or 1, and each of n4 to n6 is independently an integer of 0 to 2.

13. The liquid crystal composition of claim 12 , wherein the compound having the structure represented by formula C-1 is a compound having a structure represented by formula C-2:

wherein R C1 , R C2 , Z C , X, and n1 to n6 are the same as those in formula C-1.

14. The liquid crystal composition of claim 13 , wherein the compound having the structure represented by formula C-2 is a compound having a structure represented by formula C-3 or formula C-4:

wherein R C1 , R C2 , Z C , X, n1, n4, and n6 are the same as those in formula C-1.

15. The liquid crystal composition of claim 14 , wherein the compound having the structure represented by formula C-3 or formula C-4 is a compound having a structure represented by any one of formulas C-5 to C-8:

16. A display device comprising:

an insulating substrate; and

a liquid crystal layer disposed on the insulating substrate and comprising a compound having a structure represented by formula A-1:

wherein

R A1 is an alkyl group, an alkoxy group, a cyano group, a halogen atom, or a hydrogen atom, R A2 is an alkyl group, a cyano group, a halogen atom or a hydrogen atom, Z A is *—O—*, *—COO—*, *—OCO—*, *—CF 2 O—*, *—OCF 2 —*, *—CH 2 O—*, *—OCH 2 —*, *—SCH 2 —*, *—CH 2 S—*, *—C 2 F 4 —*, *—CH 2 CF 2 —*, *—CF 2 CH 2 —*, *—(CH 2 ) k —*, *—CH═CH—*, *—CF═CF—*, *—CH═CF—*, *—CF═CH—*, *—C≡C—*, *—CH═CHCH 2 O—*, or a single bond, X is a halogen atom, l1 is an integer of 0 to 2, l2 is an integer of 0 to 3, and when l1 is 2

and Z A in a repeating unit defined by l1 are the same or different, k is an integer of 1 to 5, and “*” indicates a point of attachment.

17. The display device of claim 16 , wherein the liquid crystal layer further comprises a compound having a structure represented by formula B-1:

wherein each of

is independently

R B1 is an alkyl group, an alkoxy group, or a hydrogen atom, R B2 is an alkyl group, an alkoxy group, an acetamide group, a hydroxyl group, or a hydrogen atom, each of Z B1 , Z B2 and Z B3 is independently an alkylene group having a carbon number of 1 to 5, an alkenylene group having a carbon number of 2 to 3, *—O—*, *—COO—*, *—OCO—*, *—CF 2 O—*, *—OCF 2 —*, a single bond, or a double bond, and each of m1 and m2 is independently 0 or 1.

18. The display device of claim 17 , further comprising an alignment layer disposed between the insulating substrate and the liquid crystal layer, wherein the alignment layer comprises a main alignment layer, which comprises a main chain having an imide group as a repeating unit, and an alignment stabilization layer comprising a crosslinked polymer comprising a compound having a structure represented by formula C-1:

wherein each of R C1 and R C2 is independently

Z C is an alkylene group, an alkyleneoxy group, an ether group or a single bond, X is a halogen atom, n1 is an integer of 2 to 4, each of n2 and n3 is independently 0 or 1, and each of n4 to n6 is independently an integer of 0 to 2.

19. The display device of claim 18 , wherein the liquid crystal layer further comprises the compound having the structure represented by formula C-1, wherein the compound having the structure represented by formula C-1 is present in an amount of about 100 ppm or less based on a total weight of the liquid crystal layer.

20. The display device of claim 19 , further comprising:

a first electrode disposed between the insulating substrate and the alignment layer; and

a second electrode facing the first electrode, and the liquid crystal layer disposed between the first electrode and the second electrode.