Biphenyl derivatives and organic electroluminescent device employing the same

1. A biphenyl derivative represented by formula 1:

wherein:

R 1 and R 2 are independently a hydrogen; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 6-20 aryl group; and a C 6-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group, and —N(R)(R′);

Ar 1 , Ar 2 , Ar 3 and Ar 4 are independently a hydrogen; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 6-20 aryl group; and a C 6-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C- 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group and —N(R)(R′) or at least one selected from the group consisting of Ar 1 and Ar 2 , and Ar 3 and Ar 4 are joined together to form a fused ring structure with the N to which they are attached; and

R, R′ and R″ are independently selected from the group consisting of a hydrogen atom, a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group and a C 4-10 heteroaryl group.

2. The biphenyl derivative of claim 1 , wherein in formula 1, —N(Ar 1 )(Ar 2 ) and/or —N(Ar 3 )(Ar 4 ) are independently a group represented by formula 2:

wherein:

X is a single bond or —(CH 2 ) n —, where n is an integer of 1˜2, —C(R 3 )(R 4 )—, —CH═CH—, —S—, —O— or —Si(R 3 )(R 4 )—;

A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , A 8 , R 3 , and R 4 , are independently a hydrogen atom; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 5-20 aryl group; and a C 5-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group and —N(R)(R′), at least one selected from the group consisting of A 1 and A 2 , A 2 and A 3 , A 3 and A 4 , A 5 and A 6 , A 6 and A 7 , and A 7 and A 8 being interconnected, respectively; and

R, R′ and R″ are independently selected from the group consisting of a hydrogen, a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group and a C 4-10 heteroaryl group.

3. The biphenyl derivative of claim 2 , wherein the group represented by formula (2) is one selected from the group consisting of groups (2a) through (2h):

wherein:

A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , A 8 , R 3 and R 4 are independently a hydrogen atom; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 5-20 aryl group; and a C 5-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group and —N(R)(R′), at least one selected from the group consisting of A 1 and A 2 , A 2 and A 3 , A 3 and A 4 , A 5 and A 6 , A 6 and A 7 , and A 7 and A 8 being interconnected, respectively; and

R, R′ and R″ are independently selected from the group consisting of a hydrogen, a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group and a C 4-10 heteroaryl group.

4. The biphenyl derivative of claim 1 , wherein in formula 1, —N(Ar 1 )(Ar 2 ) and/or —N(Ar 3 )(Ar 4 ) are independently a group represented by formula 3:

wherein R 5 and R 6 are independently a hydrogen; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 5-20 aryl group; and a C 5-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group and —N(R)(R′), R, R′ and R″ being independently selected from the group consisting of a hydrogen, a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group and a C 4-10 heteroaryl group.

5. The biphenyl derivative of claim 4 , wherein in formula 3, R 5 and R 6 are independently a group represented by formula 4:

wherein B 1 , B 2 , B 3 , B 4 and B 5 are independently a hydrogen; a C 1-20 linear or branched alkyl group; a C 5-20 cycloalkyl group; a C 6-20 aryl group; and a C 6-20 aryl group having at least one substituent selected from the group consisting of a halogen atom, a C 1-10 halogenated alkyl group, —Si(R)(R′)(R″), a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, a C 4-10 heteroaryl group and —N(R)(R′), R, R′ and R″ being independently selected from the group consisting of a hydrogen, a C 1-10 alkyl group, a C 1-10 alkoxy group, a C 6-10 aryl group, and a C 4-10 heteroaryl group.

6. The biphenyl derivative of claim 1 , wherein the compound represented by formula 1 is at least one selected from the group consisting of compounds represented by formulas 1a through 1e;.

7. An organic EL device comprising an organic layer positioned between a pair of electrodes, the organic layer containing the biphenyl derivative of any one of claims 1 through 6 .

8. The organic EL device of claim 7 , wherein the organic layer is an emissive layer or a hole blocking layer.

9. The organic EL device of claim 7 , wherein the organic layer is an emissive layer, the emissive layer comprising 70 to 99.9% by weight of the biphenyl derivative and 0.1 to 30% by weight of a dopant.