Red phosphorescent compound and organic electroluminescent device using the same

1. A red phosphorescent compound represented by Formula 1 below:

wherein

R1, R2, R3 and R4 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof, in which at least two of R1, R2, R3 and R4 are each independently selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof,

or

each of R1, R2, R3 and R4 is halogen;

when each of R1, R2 and R4 is C 1 -C 6 alkyl, R3 is selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof;

when each of R1 and R3 is C 1 -C 6 alkyl or C 1 -C 6 alkoxy, R2 or R4 is selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof; and

when each of R1 and R4 is C 1 -C 6 alkyl or C 1 -C 6 alkoxy, R2 or R3 is selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof;

is selected from 2,4-pentanedione

2,2,6,6-tetramethylheptane-3,5-dione

1,3-propanedione

1,3-butanedione

3,5-heptanedione,

1,1,1-trifluoro-2,4-pentanedione

1,1,1,5,5,5-hexafluoro-2,4-pentanedione

and 2,2-dimethyl-3,5-hexanedione

and

when

is 2,4-pentanedione

at least one of R1, R2, R3 and R4 is not hydrogen, methyl, methoxyl, or fluoro.

2. The red phosphorescent compound according to claim 1 , wherein the C 1 -C 6 alkyl is selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, butyl and t-butyl.

3. The red phosphorescent compound according to claim 1 , wherein the C 1 -C 6 alkoxy is selected from the group consisting of methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy and t-butoxy.

4. The red phosphorescent compound according to claim 1 , wherein

is selected from 2,2,6,6-tetramethylheptane-3,5-dione

1,3-propanedione

1,3-butanedione

3,5-heptanedione

1,1,1-trifluoro-2,4-pentanedione

1,1,1,5,5,5-hexafluoro-2,4-pentanedione

and 2,2-dimethyl-3,5-hexanedione

and

is selected from the following compounds:

5. The red phosphorescent compound according to claim 1 , wherein the compound of Formula 1 is selected from the following compounds:

6. The red phosphorescent compound according to claim 1 , wherein each of R1, R2, R3 and R4 is halogen selected from the group consisting of F, Cl and Br.

7. The red phosphorescent compound according to claim 1 , wherein each of R1, R2, R3 and R4 is independently selected from the group consisting of ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy and t-butoxy.

8. The red phosphorescent compound according to claim 1 , wherein

is selected from the following compounds:

9. The red phosphorescent compound according to claim 1 , wherein R3 is selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof.

10. The red phosphorescent compound according to claim 1 , wherein

R3 is selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof, and

at least two of R1, R2 and R4 are each independently selected from the group consisting of substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 1 -C 6 alkoxy and combinations thereof.

11. The red phosphorescent compound according to claim 1 , wherein at least one of R1, R2, R3 and R4 is not hydrogen, methyl, methoxyl, or fluoro.

12. The red phosphorescent compound according to claim 1 , wherein when

is 2,4-pentanedione

at least one of R1, R2, R3 and R4 is not hydrogen, methyl, methoxyl or F.

13. The red phosphorescent compound according to claim 1 , wherein when

is 2,4-pentanedione

or 1,1,1,5,5,5-hexafluoro-2,4-pentanedione

at least one of R1, R2, R3 and R4 is not hydrogen, methyl, methoxyl, or fluoro.

14. A red phosphorescent compound represented by Formula 2 below:

wherein

wherein R1, R2, R3 and R4 are each independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl and C 1 -C 4 alkoxy, in which at least one of R1, R2, R3 and R4 is C 1 -C 6 alkyl or C 1 -C 4 alkoxy;

R5, R6 and R7 are each independently selected from hydrogen, C 1 -C 6 alkyl, C 1 -C 4 alkoxy, and combinations thereof, in which at least two of R5, R6 and R7 are each independently selected from the group consisting of C 1 -C 6 alkyl, C 1 -C 4 alkoxy, and combinations thereof;

is selected from 2,4-pentanedione

2,2,6,6-tetramethylheptane-3,5-dione

1,3-propanedione

1,3-butanedione

3,5-heptanedione

1,1,1-trifluoro-2,4-pentanedione

1,1,1,5,5,5-hexafluoro-2,4-pentanedione

and 2,2-dimethyl-3,5-hexanedione

and

when

is 2,4-pentanedione

at least one of R1, R2, R3, R4, R5, R6 and R7 is not hydrogen, methyl or methoxy.

15. The red phosphorescent compound according to claim 14 , wherein

the C 1 -C 6 alkyl is selected from the group consisting of methyl, ethyl, n-propyl, propyl, n-butyl, i-butyl and t-butyl, and

the C 1 -C 4 alkoxy is selected from the group consisting of methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy and t-butoxy.

16. The red phosphorescent compound according to claim 14 , wherein

is selected from 2,2,6,6-tetramethylheptane-3,5-dione

1,3-propanedione

1,3-butanedione

3,5-heptanedione

1,1,1-trifluoro-2,4-pentanedione

1,1,1,5,5,5-hexafluoro-2,4-pentanedione

and 2,2-dimethyl-3,5-hexanedione

and

is selected from the following compounds:

17. The red phosphorescent compound according to claim 14 , wherein the compound of Formula 1 is selected from the following compounds:

18. The red phosphorescent compound according to claim 14 , wherein

is selected from the following compounds:

19. An organic electroluminescent (EL) device comprising a light-emitting layer interposed between an anode electrode and a cathode electrode wherein the compound according to any one of claims 1 - 5 , 14 , 15 , 16 & 17 is used as a dopant for the light-emitting layer.

20. The organic electroluminescent (EL) device according to claim 19 , wherein the light-emitting layer uses, as a host, one selected from an Al complex, a Zn complex and a carbazole derivative.

21. The organic electroluminescent (EL) device according to claim 20 , wherein the Al or Zn complex has at least one ligand selected from quinol, biphenyl, isoquinol, phenyl, methylquinol, dimethylquinol and dimethylisoquinol, and the carbazole derivative is 4,4′-N,N′-dicarbazole biphenyl (CBP).

22. The organic electroluminescent (EL) device according to claim 19 , wherein the dopant is used in an amount of 0.1 to 50% by weight.

23. The organic electroluminescent (EL) device according to claim 19 , wherein the organic EL device exhibits an operation voltage of at least 6.0 V or less, a luminance of at least 1,300 cd/m 2 or higher, and a lifetime of about 6,500 hours or longer.