Organic light-emitting device, method of manufacturing the same, and flat panel display device including the same

1. An organic light-emitting device comprising:

a substrate; a first electrode; a second electrode; an emission layer between the first electrode and the second electrode; and an electron transport layer between the emission layer and the second electrode,

wherein:

the emission layer comprises a blue emission layer,

the electron transport layer comprises a unit comprising a first single layer including a first material, a first mixed layer on the first single layer and including the first material and a second material, a second single layer on the first mixed layer and including the second material, a second mixed layer on the second single layer and including the first and second materials, and a third single layer on the second mixed layer and including the first material,

wherein the first mixed layer has a thickness larger than that of the second mixed layer, and

wherein the first material comprises at least one selected from the group consisting of a 9,10-diaryl-anthracene-based material, a compound represented by Formula 1 below, and a compound represented by Formula 2 below:

wherein, in Formulae 1 and 2, R 1 to R 6 are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a substituted or unsubstituted C 1 -C 30 alkyl group, a substituted or unsubstituted C 1 -C 30 alkoxy group, a substituted or unsubstituted C 1 -C 30 acyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 5 -C 30 aryl group, or a substituted or unsubstituted C 2 -C 30 heteroaryl group, wherein at least two adjacent groups of R 1 to R 6 are selectively bonded to each other to form a saturated or unsaturated ring;

L 1 is a single bond, a substituted or unsubstituted C 1 -C 30 alkylene group, a substituted or unsubstituted C 5 -C 30 arylene group, or a substituted or unsubstituted C 2 -C 30 hetero arylene group;

Q 1 to Q 9 are each independently a hydrogen atom, a substituted or unsubstituted C 5 C 30 aryl group, or a substituted or unsubstituted C 3 -C 30 heteroaryl group; and

a is an integer from 1 to 10.

2. The organic light-emitting device of claim 1 , wherein the electron transport layer comprises a plurality of units comprising the unit, each of the plurality of units being identical with one another.

3. The organic light-emitting device of claim 1 , wherein a thickness ratio of the first mixed layer to the second mixed layer is from about 2:1 to about 5:1.

4. The organic light-emitting device of claim 1 , wherein the first mixed layer has a thickness that is larger than that of the third mixed layer.

5. The organic light-emitting device of claim 1 , wherein a thickness ratio of the first single layer to the third single layer is from about 2:1 to about 5:1.

6. The organic light-emitting device of claim 1 , wherein the first single layer, the second single layer, and the third single layer each independently have a thickness of from about 1 Å to about 100 Å.

7. The organic light-emitting device of claim 1 , wherein the first mixed layer and the second mixed layer each independently have a thickness of from about 10 Å to about 300 Å.

8. The organic light-emitting device of claim 1 , wherein one of the first single layer, the second single layer, and the third single layer has a thickness smaller than that of one of the first mixed layer and the second mixed layer.

9. The organic light-emitting device of claim 1 , wherein the second material in at least one of the first mixed layer and the second mixed layer has a concentration gradient.

10. The organic light-emitting device of claim 1 , wherein the first material comprises at least one of a compound 5, a compound 6 and a compound 7 represented by the following formulae:

11. The organic light-emitting device of claim 1 , wherein the second material comprises a lithium (Li) complex.

12. The organic light-emitting device of claim 1 , wherein the second material comprises at least one of lithium quinolate and a compound 8 represented by the following formula:

13. The organic light-emitting device of claim 1 , further comprising at least one of a hole injection layer and a hole transport layer between the first electrode and the emission layer.

14. The organic light-emitting device of claim 1 , further comprising an electron injection layer between the electron transport layer and the second electrode.

15. The organic light-emitting device of claim 1 , wherein the electron transport layer further comprises: a fourth single layer on the third single layer and including the first material; a third mixed layer on the fourth single layer and including the first and second materials; a fifth single layer on the third mixed layer material and including the second material; a fourth mixed layer on the fifth single layer and including the first and second materials; and a sixth single layer on the fourth mixed layer and including the first material,

wherein the third mixed layer has a thickness larger than that of the fourth mixed layer, and the fourth single layer has a thickness larger than that of the sixth single layer.

16. A method of manufacturing an organic light-emitting device, the method comprising:

forming a first electrode on a substrate; forming an emission layer on the first electrode; forming an electron transport layer on the emission layer; and forming a second electrode on the electron transport layer,

wherein the forming of the electron transport layer comprises:

preparing a first deposition source for discharging a first material, and a second deposition source for discharging a second material;

disposing the first deposition source and the second deposition source to be so separated from each other that a first material discharging region and a second material discharging region at least partially overlap with each other; and

reciprocating the first deposition source and the second deposition source at least once between first and second ends of a region for forming the electron transport layer to form a unit comprising a first single layer including a first material, a first mixed layer on the first single layer and including the first material and a second material, a second single layer on the first mixed layer and including the second material, a second mixed layer on the second single layer and including the first and second materials, and a third single layer on the second mixed layer and including the first material,

wherein the first mixed layer has a thickness larger than that of the second mixed layer, and

wherein the first material comprises at least one selected from the group consisting of a 9,10-diaryl-anthracene-based material, a compound represented by Formula 1 below, and a compound represented by Formula 2 below:

wherein, in Formulae 1 and 2, R 1 to R 6 are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a substituted or unsubstituted C 1 -C 30 alkyl group, a substituted or unsubstituted C 1 -C 30 alkoxy group, a substituted or unsubstituted C 1 -C 30 acyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 5 -C 30 aryl group, or a substituted or unsubstituted C 2 -C 30 heteroaryl group, wherein at least two adjacent groups of R 1 to R 6 are selectively bonded to each other to form a saturated or unsaturated ring;

L 1 is a single bond, a substituted or unsubstituted C 1 -C 30 alkylene group, a substituted or unsubstituted C 5 -C 30 arylene group, or a substituted or unsubstituted C 2 -C 30 hetero arylene group;

Q 1 to Q 9 are each independently a hydrogen atom, a substituted or unsubstituted C 5 -C 30 aryl group, or a substituted or unsubstituted C 3 -C 30 heteroaryl group; and

a is an integer from 1 to 10.

17. The method of claim 16 , wherein the reciprocating of the first deposition source and the second deposition source is performed twice.

18. A flat panel display device comprising: a transistor comprising a source, a drain, a gate, and an active layer; and the organic light-emitting device according to claim 1 , wherein one of the source and drain of the transistor is electrically connected to the first electrode of the organic light-emitting device.