Organic light-emitting device

1. An organic light-emitting device, comprising:

an anode;

a cathode; and

an organic layer between the anode and the cathode, the organic layer including:

an emission layer (EML), the EML including a first host and a second host that are different from one another,

a hole transport region between the anode and the EML, the hole transport region including at least one of a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, or an electron blocking layer (EBL),

an electron transport region between the EML and the cathode, the electron transport region including at least one of a hole blocking layer (HBL), an electron transport layer (ETL), or an electron injection layer (EIL), and

an intermediate layer between the EML and the electron transport region;

wherein the intermediate layer includes a compound having an electron affinity of more than 0 eV and less than 2.5 eV, and

wherein an electron affinity of the intermediate layer compound [EA intermediate layer ] and an electron affinity of a compound of the ETL [EA ETL ] satisfy a relationship represented by the following expression:

EA ETL ≧EA intermediate layer +0.3 eV.

2. The organic light-emitting device as claimed in claim 1 , wherein the EML is a phosphorescent EML.

3. The organic light-emitting device as claimed in claim 1 , wherein a relationship of electron affinities (EA host1 ) and (EA host2 ) and ionization potentials (IP host1 ) and (IP host2 ) of the first host and the second host satisfy at least one of the following expressions:

EA host1 ≧EA host2 +0.3 eV  (1)

IP host2 ≧IP host1 +0.3 eV  (2).

4. The organic light-emitting device as claimed in claim 1 , wherein the EML is a phosphorescent EML, the EML including a dopant that emits phosphorescence having a main peak of at least 450 nm.

5. The organic light-emitting device as claimed in claim 1 , wherein:

the EML is a phosphorescent EML, the EML including a dopant that emits phosphorescence having a main peak of at least 450 nm, and

at least one of the first host or the second host is a compound that includes a tryphenylene moiety or a carbazole moiety.

6. The organic light-emitting device as claimed in claim 1 , wherein:

the intermediate layer contacts the EML, and

the compound having an electron affinity of more than 0 eV and less than 2.5 eV includes a tryphenylene moiety or a carbazole moiety.

7. The organic light-emitting device as claimed in claim 4 , wherein a triplet energy of the intermediate layer compound [E T IL (eV)] is greater than that of the dopant that emits phosphorescence [E T d (eV)].

8. The organic light-emitting device as claimed in claim 1 , wherein:

the intermediate layer compound has a triplet energy of at least 2.2 eV when the EML emits red phosphorescence,

the intermediate layer compound has a triplet energy of at least 2.4 eV when the EML emits green phosphorescence, and

the intermediate layer compound has a triplet energy of at least at least 2.6 eV when the EML emits blue phosphorescence.

9. The organic light-emitting device as claimed in claim 1 , wherein the hole transport region includes a p-dopant.

10. The organic light-emitting device as claimed in claim 1 , wherein the hole transport region includes a p-dopant, the p-dopant including a quinone derivative, a metal oxide, or a cyano group-containing compound.

11. The organic light-emitting device as claimed in claim 1 , wherein the EML is a phosphorescent EML and the EML includes a dopant, the dopant including an Ir-complex, a Pt-complex, an Os-complex, or a Cu-complex.

12. The organic light-emitting device as claimed in claim 1 , wherein the intermediate layer compound is represented by Formula 1 below:

wherein, in Formula 1,

X is a single bond or NR 4 ;

R 1 to R 4 are each independently a hydrogen, a deuterium, —P(═O)R 51 R 52 , a substituted or unsubstituted C 1 -C 60 alkyl group, a substituted or unsubstituted C 1 -C 60 heteroalkyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 2 -C 60 heteroaryl group, a substituted or unsubstituted C 6 -C 60 condensed polycyclic group, or a C 6 -C 30 arylamine group; and/or adjacent substituents of R 2 and R 3 link together to form a ring;

L is a single bond, a substituted or unsubstituted C 6 -C 60 arylene group, a substituted or unsubstituted C 1 -C 60 heteroarylene group, or a linkage connecting 2 to 5 of the arylene groups or the heteroarylene groups;

R 51 and R 52 are each independently a substituted or unsubstituted C 1 -C 60 alkyl group, a substituted or unsubstituted C 1 -C 60 heteroalkyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 2 -C 60 heteroaryl group, a substituted or unsubstituted C 6 -C 60 condensed polycyclic group, or a C 6 -C 30 arylamine group;

m, n, and o are each independently an integer selected from 1 to 4, and when any of m, n, and o is 2 or greater, R 1 to R 3 are the same or different from each other; and

p is an integer selected from 0 and 1, and when p is 0, a benzene moiety substituted with R 2 and a benzene moiety substituted with R 3 are not connected in an X-shape.

13. The organic light-emitting device as claimed in claim 12 , wherein R 1 to R 4 are each independently a hydrogen, a deuterium, a substituted or unsubstituted C 1 -C 30 alkyl group, a substituted or unsubstituted C 1 -C 30 heteroalkyl group, a substituted or unsubstituted C 6 -C 30 arylamine group, or a group represented by one of Formulae 2a to 2x below:

wherein, in Formulae 2a to 2x,

R 11 , R 12 , Z 1 , and Z 2 are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 6 -C 20 aryl group, a substituted or unsubstituted C 2 -C 20 heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic hetero-condensed polycyclic group;

Y 1 and Y 2 are each independently CH or N;

p and q are each independently an integer selected from 1 to 9;

when p or q is 2 or greater, a plurality of Z 1 or Z 2 are identical to or different from each other; and

* indicates a binding site with a neighboring atom.

14. The organic light-emitting device as claimed in claim 12 , wherein L is a single bond or a group represented by one of Formulae 3a to 3z below:

wherein, in Formulae 3a to 3z, R 11 and R 12 are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 6 -C 20 aryl group, a substituted or unsubstituted C 2 -C 20 heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic hetero-condensed polycyclic group; and

* indicates a binding site with a neighboring atom.

15. The organic light-emitting device as claimed in claim 10 , wherein at least one of the first host or the second host is one of the following compounds:

16. The organic light-emitting device as claimed in claim 4 , wherein the EML is a phosphorescent EML, the phosphorescent EML including an Ir-complex as a dopant.

17. The organic light-emitting device as claimed in claim 1 , wherein the intermediate layer compound is one of the following compounds:

18. The organic light-emitting device as claimed in claim 1 , wherein the organic layer is formed by performing a wet process.

19. A flat panel display comprising the organic light-emitting device as claimed in claim 1 , wherein the first electrode of the organic light-emitting device is electrically connected to a source electrode or a drain electrode of a thin film transistor.

20. An organic light-emitting device, comprising:

an anode;

a cathode; and

an organic layer between the anode and the cathode, the organic layer including:

an emission layer (EML), the EML including a first host and a second host that are different from one another,

a hole transport region between the anode and the EML, the hole transport region including at least one of a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, or an electron blocking layer (EBL),

an electron transport region between the EML and the cathode, the electron transport region including at least one of a hole blocking layer (HBL), an electron transport layer (ETL), or an electron injection layer (EIL), and

an intermediate layer between the EML and the electron transport region;

wherein the intermediate layer includes a compound having an electron affinity of more than 0 eV and less than 2.5 eV, and

wherein:

the intermediate layer compound has a triplet energy of at least 2.2 eV when the EML emits red phosphorescence,

the intermediate layer compound has a triplet energy of at least 2.4 eV when the EML emits green phosphorescence, and

the intermediate layer compound has a triplet energy of at least at least 2.6 eV when the EML emits blue phosphorescence.

21. An organic light-emitting device, comprising:

an anode;

a cathode; and

an organic layer between the anode and the cathode, the organic layer including:

an emission layer (EML), the EML including a first host and a second host that are different from one another,

a hole transport region between the anode and the EML, the hole transport region including at least one of a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, or an electron blocking layer (EBL),

an electron transport region between the EML and the cathode, the electron transport region including at least one of a hole blocking layer (HBL), an electron transport layer (ETL), or an electron injection layer (EIL), and

an intermediate layer between the EML and the electron transport region;

wherein the intermediate layer includes a compound having an electron affinity of more than 0 eV and less than 2.5 eV, and

wherein the intermediate layer compound is represented by Formula 1 below:

wherein, in Formula 1,

X is a single bond or NR 4 ;

R 1 to R 4 are each independently a hydrogen, a deuterium, a substituted or unsubstituted C 1 -C 30 alkyl group, a substituted or unsubstituted C 1 -C 30 heteroalkyl group, a substituted or unsubstituted C 6 -C 30 arylamine group, or a group represented by one of Formulae 2a to 2x below;

L is a single bond, a substituted or unsubstituted C 6 -C 60 arylene group, a substituted or unsubstituted C 1 -C 60 heteroarylene group, or a linkage connecting 2 to 5 of the arylene groups or the heteroarylene groups;

R 51 and R 52 are each independently a substituted or unsubstituted C 1 -C 60 alkyl group, a substituted or unsubstituted C 1 -C 60 heteroalkyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 2 -C 60 heteroaryl group, a substituted or unsubstituted C 6 -C 60 condensed polycyclic group, or a C 6 -C 30 arylamine group;

m, n, and o are each independently an integer selected from 1 to 4, and when any of m, n, and o is 2 or greater, R 1 to R 3 are the same or different from each other; and

p is an integer selected from 0 and 1, and when p is 0, a benzene moiety substituted with R 2 and a benzene moiety substituted with R 3 are not connected in an X-shape,

wherein, in Formulae 2a to 2x,

R 11 , R 12 , Z 1 , and Z 2 are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 6 -C 20 aryl group, a substituted or unsubstituted C 2 -C 20 heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic hetero-condensed polycyclic group;

Y 1 and Y 2 are each independently CH or N;

p and q are each independently an integer selected from 1 to 9;

when p or q is 2 or greater, a plurality of Z 1 or Z 2 are identical to or different from each other; and

* indicates a binding site with a neighboring atom.