Organic light emitting device and display device having the same

1. An organic light emitting device, comprising:

a first electrode;

a hole transport region on the first electrode;

an emission layer on the hole transport region;

an electron transport region on the emission layer; and

a second electrode on the electron transport region,

wherein the electron transport region comprises:

an electron transport layer on the emission layer;

a first mixed electron transport layer on the electron transport layer; and

a second mixed electron transport layer on the first mixed electron transport layer,

wherein the first mixed electron transport layer comprises:

a first electron transport compound and a second electron transport compound different from the first electron transport compound mixed at a first ratio,

wherein the second mixed electron transport layer comprises:

the first electron transport compound and the second electron transport compound mixed at a second ratio different from the first ratio,

wherein the first ratio is from about 3:7 to about 7:3, and the second ratio is from about 4:6 to about 6:4, and

wherein a lowest unoccupied molecular orbital value of the electron transport layer is greater than a lowest unoccupied molecular orbital value of the first mixed electron transport layer by about −0.2 eV or greater.

2. The organic light emitting device of claim 1 , wherein the first electron transport compound is selected from compounds represented by following Formula Group 1:

wherein in Formula Group 1,

Ar 1 to Ar 6 are each independently selected from hydrogen, deuterium, a substituted or unsubstituted aromatic group, a substituted or unsubstituted condensed aromatic group, a substituted or unsubstituted heteroaromatic group and a substituted or unsubstituted condensed heteroaromatic group, excluding a compound where Ar 2 is 1,3,5-trimethylphenyl group;

X is a phenylene group or a pyridylene group;

P is an integer from 0 to 2, where when P is 2, the two Xs are the same or different; and

Z 1 to Z 3 are each independently C or N, excluding a compound where Z 3 is C and each of Ar 5 and Ar 6 is a phenyl group.

3. The organic light emitting device of claim 2 , wherein

Ar 1 is selected from the group consisting of an aromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; a condensed aromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; a heteroaromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; and a condensed heteroaromatic group substituted with an alkyl group, a phenyl group or a pyridyl group;

Ar 2 is a condensed phenyl group excluding a substituted or unsubstituted phenyl group or an element in group 16;

Ar 3 is a phenyl group, a pyridyl group or a pyrimidyl group;

Ar 4 is a substituted or unsubstituted aromatic group having two to four rings or a substituted or unsubstituted heteroaromatic group having two to four rings; and

Ar 5 and Ar 6 are each independently a phenyl group or a pyridyl group.

4. The organic light emitting device of claim 1 , wherein the first electron transport compound is represented by following Formula 1:

5. The organic light emitting device of claim 2 , wherein the electron transport layer comprises the first electron transport compound.

6. The organic light emitting device of claim 1 , wherein the second electron transport compound is at least one of LiF, Lithium quinolate (LiQ), Li 2 O, BaO, NaCl, CsF, Yb, RbCl and RbI.

7. The organic light emitting device of claim 1 , wherein the emission layer comprises a dopant represented by following Formula 2:

wherein in Formula 2,

L 1 and L 2 are each independently selected from hydrogen, deuterium, a substituted or unsubstituted C6-C30 arylene group and a substituted or unsubstituted C2-C30 heteroarylene group;

Ar 7 to Ar 10 are each independently selected from hydrogen, deuterium, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group and a substituted or unsubstituted C2-C30 heteroaryl group; and

R 1 to R 9 are each independently selected from hydrogen, deuterium, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C3-C10 cycloalkenyl group, a substituted or unsubstituted C1-C10 heterocycloalkyl group, a substituted or unsubstituted C2-C10 heterocycloalkenyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C1-C30 heteroaryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30 arylthio group and a monovalent C6-C30 non-aromatic condensed polycyclic group.

8. The organic light emitting device of claim 7 , wherein the dopant is represented by the following Formula 3:

9. The organic light emitting device of claim 1 , wherein the electron transport layer comprises at least one of tris(8-hydroxyquinolinato)aluminum (Alq3), 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum (BAlq), berylliumbis(benzoquinolin-10-olate) (Bebq2) and 9,10-di(naphthalene-2-yl)anthracene (ADN).

10. A display device comprising a plurality of pixels,

wherein at least one of the pixels comprises:

a first electrode;

a hole transport region on the first electrode;

an emission layer on the hole transport region;

an electron transport region on the emission layer; and

a second electrode on the electron transport region,

wherein the electron transport region comprises:

an electron transport layer on the emission layer;

a first mixed electron transport layer on the electron transport layer; and

a second mixed electron transport layer on the first mixed electron transport layer,

wherein the first mixed electron transport layer comprises:

a first electron transport compound and a second electron transport compound different from the first electron transport compound mixed at a first ratio,

wherein the second mixed electron transport layer comprises:

the first electron transport compound and the second electron transport compound mixed at a second ratio different from the first ratio,

wherein the first ratio is from about 3:7 to about 7:3, and the second ratio is from about 4:6 to about 6:4, and

wherein a lowest unoccupied molecular orbital value of the electron transport layer is greater than a lowest unoccupied molecular orbital value of the first mixed electron transport layer by about −0.2 eV or greater.

11. The display device of claim 10 , wherein the first electron transport compound is selected from compounds represented by following Formula Group 1:

wherein in Formula Group 1,

Ar 1 to Ar 6 are each independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted aromatic group, a substituted or unsubstituted condensed aromatic group, a substituted or unsubstituted heteroaromatic group and a substituted or unsubstituted condensed heteroaromatic group, excluding a compound where Ar 2 is 1,3,5-trimethylphenyl group;

X is a phenylene group or a pyridylene group;

P is an integer from 0 to 2, where when P is 2, the two Xs are the same or different; and

Z 1 to Z 3 are each independently C or N, excluding a compound where Z 3 is C and each of Ar 5 and Ar 6 is a phenyl group.

12. The display device of claim 11 , wherein

Ar 1 is selected from the group consisting of an aromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; a condensed aromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; a heteroaromatic group substituted with an alkyl group, a phenyl group or a pyridyl group; and a condensed heteroaromatic group substituted with an alkyl group, a phenyl group or a pyridyl group;

Ar 2 is a condensed phenyl group excluding a substituted or unsubstituted phenyl group or an element in group 16;

Ar 3 is a phenyl group, a pyridyl group or a pyrimidyl group;

Ar 4 is a substituted or unsubstituted aromatic group having two to four rings or a substituted or unsubstituted heteroaromatic group having two to four rings; and

Ar 5 and Ar 6 are each independently a phenyl group or a pyridyl group.

13. The display device of claim 10 , wherein the first electron transport compound is represented by following Formula 1:

14. The display device of claim 11 , wherein the electron transport layer comprises the first electron transport compound.

15. The display device of claim 10 , wherein the second electron transport compound is at least one of LiF, Lithium quinolate (LiQ), Li 2 O, BaO, NaCl, CsF, Yb, RbCl and RbI.

16. The display device of claim 10 , wherein the emission layer comprises a dopant represented by following Formula 2:

wherein in Formula 2,

L 1 and L 2 are each independently selected from hydrogen, deuterium, a substituted or unsubstituted C6-C30 arylene group and a substituted or unsubstituted C2-C30 heteroarylene group;

Ar 7 to Ar 10 are each independently selected from hydrogen, deuterium, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group and a substituted or unsubstituted C2-C30 heteroaryl group; and

R 1 to R 9 are each independently selected from hydrogen, deuterium, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C3-C10 cycloalkenyl group, a substituted or unsubstituted C1-C10 heterocycloalkyl group, a substituted or unsubstituted C2-C10 heterocycloalkenyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C1-C30 heteroaryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30 arylthio group and a monovalent C6-C30 non-aromatic condensed polycyclic group.

17. The display device of claim 16 , wherein the dopant is represented by the following Formula 3:

18. The display device of claim 10 , wherein the electron transport layer comprises at least one of tris(8-hydroxyquinolinato)aluminum (Alq3), 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum (BAlq), berylliumbis(benzoquinolin-10-olate) (Bebq2) and 9,10-di(naphthalene-2-yl)anthracene (ADN).

19. The organic light emitting device of claim 1 , wherein the electron transport layer consists of the first electron transport compound, the first mixed electron transport layer consists of the first electron transport compound and the second electron transport compound, and the second mixed electron transport layer consists of the first electron transport compound and the second electron transport compound.