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

1. An organic electroluminescent device comprising organic layers comprising at least a hole-injecting layer, a hole-transporting layer, and a light-emitting layer sandwiched between an anode and a cathode,

wherein 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

wherein the light-emitting layer contains a fluorescent light-emitting material, and an electron- and/or exciton-blocking layer containing an indolocarbazole compound represented by general formula (1) is disposed between the hole-transporting layer and the light-emitting layer so as to be adjacent to the light-emitting layer:

in general formula (1), Z is an n-valent aromatic hydrocarbon group of 6 to 50 carbon atoms or an n-valent aromatic heterocyclic group of 3 to 50 carbon atoms; Y is a group represented by formula (1a); n is an integer of 2 to 6; Y's may be identical with or different from each other when n is 2 or more,

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

in formula (1b), X is a methine group or a nitrogen atom; R 3 is a hydrogen atom, an aliphatic hydrocarbon group of 1 to 10 carbon atoms, an aromatic hydrocarbon group of 6 to 12 carbon atoms, or an aromatic heterocyclic group of 3 to 11 carbon atoms; R 3 may be fused to a ring containing X to form a fused ring, and

in formula (1c), Ar is an aromatic hydrocarbon group of 6 to 50 carbon atoms or an aromatic heterocyclic group of 3 to 50 carbon atoms, and

wherein the LUMO energy of the indolocarbazole compound contained in the electron- and/or exciton-blocking layer is higher than the LUMO energy of the fluorescent light-emitting material contained in the light-emitting layer, the LUMO energy in eV of the indolocarbazole compound being greater than or equal to −1.2, and

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

2. An organic electroluminescent device as described in claim 1 wherein the light-emitting layer contains a fluorescent light-emitting material and an electron-transporting host material.

3. An organic electroluminescent device as described in claim 1 wherein the indolocarbazole compound represented by general formula (1) is an indolocarbazole compound represented by the following general formula (2):

In general formula (2), ring B is a heterocyclic ring fused to the adjacent rings and represented by formula (1c); Z, Ar, R 1 , and R 2 have the same meaning as those in general formula (1); R 3 is a hydrogen atom, an aliphatic hydrocarbon group of 1 to 10 carbon atoms, an aromatic hydrocarbon group of 6 to 12 carbon atoms, or an aromatic heterocyclic group of 3 to 11 carbon atoms; n is an integer of 2.

4. An organic electroluminescent device as described in claim 1 wherein the indolocarbazole compound represented by general formula (1) is selected from indolocarbazole compounds represented by general formulas (3) to (6):

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

5. An organic electroluminescent device as described in claim 1 wherein the organic layers further comprise an electron-transporting layer and at least one of the materials used in the said electron-transporting layer has an electron mobility of 1×10 −7 cm 2 /V·s or more.

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 1 ,

wherein the light-emitting layer is a single layer.

8. 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.

9. An organic electroluminescent device according to claim 2 ,

wherein the electron-transporting host material has an electron transfer rate of 1×10 −6 cm 2 /V·s or more.