Organic electroluminescent device having an electron- and /or exciton-blocking layer comprising an indolocarbazole compound

1. An organic electroluminescent device, comprising:

an anode;

a cathode; and

organic layers comprising at least:

a hole-injecting layer;

a hole-transporting layer;

a single light-emitting layer, and

an electron-transporting layer,

the organic layers being interposed between the anode and the cathode,

wherein:

the single light-emitting layer comprises a phosphorescent light-emitting material and a host material;

the hole-transporting layer consists essentially of one or more compounds selected from the group consisting of a triazole derivative, an oxadiazole derivative, an imidazole derivative, a carbazole derivative, a polyarylalkane derivative, a pyrazoline derivative, a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, an oxazole derivative, a styrylanthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, an aniline-based copolymer, and a thiophene oligomer; and

the hole-transporting layer and the single light-emitting layer have an electron- and/or exciton-blocking layer therebetween, the electron- and/or exciton-blocking layer being adjacent to the single light-emitting layer and containing an indolocarbazole compound represented by the following general formula (1):

in the general formula (1): Z represents an n-valent aromatic hydrocarbon group having a total of 6 to 50 carbon atoms or an aromatic heterocyclic group having a total of 3 to 50 carbon atoms; Y represents a group represented by the formula (1a); n represents an integer of 2 to 6; and Y's may be identical to or different from each other;

in the formula (1a): a ring A represents an aromatic ring represented by the formula (1b) to be fused with adjacent rings; a ring B represents a heterocycle represented by the formula (1c) to be fused with adjacent rings; and R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group having a total of 1 to 10 carbon atoms, an aromatic hydrocarbon group having a total of 6 to 12 carbon atoms, or an aromatic heterocyclic group having a total of 3 to 11 carbon atoms;

in the formula (1 b): X represents a methine group or a nitrogen atom; R 3 represents a hydrogen atom, an aliphatic hydrocarbon group having a total of 1 to 10 carbon atoms, an aromatic hydrocarbon group having a total of 6 to 12 carbon atoms, or an aromatic heterocyclic group having a total of 3 to 11 carbon atoms, provided that R 3 may be fused with a ring including X to form a fused ring; and

in the formula (1c), Ar represents an aromatic hydrocarbon group having a total of 6 to 50 carbon atoms or an aromatic heterocyclic group having a total of 3 to 50 carbon atoms;

wherein:

the indolocarbazole compound contained in the electron- and/or exciton-blocking layer has a LUMO energy higher than a LUMO energy of the host material contained in the single light-emitting layer and has a LUMO energy in eV of greater than or equal to −1.2, the hole-transporting material contained in the hole-transporting layer has a HOMO energy higher than a HOMO energy of the indolocarbazole compound contained in the electron- and/or exciton-blocking layer and has a HOMO energy in eV of greater than or equal to −4.8.

2. An organic electroluminescent device according to claim 1 , wherein the host material is an electron-transporting host material.

3. An organic electroluminescent device according to claim 1 , wherein the electron-transporting layer further comprises at least one material or materials having an electron transfer rate of 1×10 −7 cm 2 N/V·s or more.

4. An organic electroluminescent device according to claim 1 , wherein the indolocarbazole compound represented by the general formula (1) comprises an indolocarbazole compound represented by the following general formula (2):

in the general formula (2): a ring B represents a heterocycle represented by the formula (1c) to be fused with adjacent rings; Z, Ar, R 1 , and R 2 have the same meanings as those in the general formula (1); R 3 represents a hydrogen atom, an aliphatic hydrocarbon group having a total of 1 to 10 carbon atoms, an aromatic hydrocarbon group having a total of 6 to 12 carbon atoms, or an aromatic heterocyclic group having a total of 3 to 11 carbon atoms; and n represents 2.

5. An organic electroluminescent device according to claim 1 , wherein the indolocarbazole compound represented by the general formula (1) is selected from indolocarbazole compounds represented by the following general formulae (3) to (6):

in the general formulae (3) to (6), Z, Ar, R 1 , R 2 , R 3 , and n have the same meanings as those in the general formula (1).

6. An organic electroluminescent device according to claim 1 ,

wherein the hole-transporting layer consists essentially of one or more compounds selected from the group consisting of a porphyrin compound, an aromatic tertiary amine compound, and a styrylamine compound.

7. An organic electroluminescent device according to claim 2 ,

wherein the electron-transporting host material has an electron transfer rate of 1×10 cm 2 /V·s or more.

8. An organic electroluminescent device according to claim 1 ,

wherein the single light-emitting layer is not adjacent to any other light-emitting layer.

9. An organic electroluminescent device according to claim 1 ,

wherein the LUMO energy and the HOMO energy are determined by a structure optimization calculation at the B3LYP/6-31G* level.

10. An organic electroluminescent device, comprising:

an anode;

a cathode; and

organic layers comprising at least:

a hole-injecting layer;

a hole-transporting layer;

a single light-emitting layer; and

an electron-transporting layer,

the organic layers being interposed between the anode and the cathode,

wherein:

the single light-emitting layer comprises a phosphorescent light-emitting material and a host material;

the hole-transporting layer consists essentially of one or more compounds selected from the group consisting of a triazole derivative, an oxadiazole derivative, an imidazole derivative, a carbazole derivative, a polyarylalkane derivative, a pyrazoline derivative, a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, an oxazole derivative, a styrylanthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, an aniline-based copolymer, and a thiophene oligomer; and

the hole-transporting layer and the single light-emitting layer have an electron- and/or exciton-blocking layer therebetween, the electron- and/or exciton-blocking layer being adjacent to the single light-emitting layer and containing an indolocarbazole compound represented by one of the following general formulae (3)-(5):

wherein in the formulae (3)-(5): Z represents an n-valent aromatic hydrocarbon group having a total of 6 to 50 carbon atoms or an aromatic heterocyclic group having a total of 3 to 50 carbon atoms;

R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group having a total of 1 to 10 carbon atoms, an aromatic hydrocarbon group having a total of 6 to 12 carbon atoms, or an aromatic heterocyclic group having a total of 3 to 11 carbon atoms;

R 3 represents a hydrogen atom, an aliphatic hydrocarbon group having a total of 1 to 10 carbon atoms, an aromatic hydrocarbon group having a total of 6 to 12 carbon atoms, or an aromatic heterocyclic group having a total of 3 to 11 carbon atoms, provided that R 3 may be fused with a ring including a methine group or a nitrogen atom to form a fused ring;

Ar represents an aromatic hydrocarbon group having a total of 6 to 50 carbon atoms or an aromatic heterocyclic group having a total of 3 to 50 carbon atoms; and n represents an integer of 2 to 6:

wherein:

the indolocarbazole compound contained in the electron- and/or exciton-blocking layer has a LUMO energy higher than a LUMO energy of the host material contained in the single light-emitting layer and has a LUMO energy in eV of greater than or equal to −1.2,

the hole-transporting material contained in the hole-transporting layer has a HOMO energy higher than a HOMO energy of the indolocarbazole compound contained in the electron- and/or exciton-blocking layer and has a HOMO energy in eV of greater than or equal to −4.8.

11. An organic electroluminescent device according to claim 10 , wherein the host material is an electron-transporting host material.

12. An organic electroluminescent device according to claim 10 , wherein the electron-transporting layer further comprises at least one material or materials having an electron transfer rate of 1×10 cm 2 /V·s or more.

13. An organic electroluminescent device according to claim 10 ,

wherein the hole-transporting layer consists essentially of one or more compounds selected from the group consisting of a porphyrin compound, an aromatic tertiary amine compound, and a styrylamine compound.

14. An organic electroluminescent device according to claim 11 ,

wherein the electron-transporting host material has an electron transfer rate of 1×10 cm 2 /V·s or more.

15. An organic electroluminescent device according to claim 10 ,

wherein the single light-emitting layer is not adjacent to any other light-emitting layer.

16. An organic electroluminescent device according to claim 10 ,

wherein the LUMO energy and the HOMO energy are determined by a structure optimization calculation at the B3LYP/6-31G* level.