Compound having carbazole ring structure, and organic electroluminescent device

Abstract

[Problem]An organic compound of excellent characteristics is provided that exhibits excellent hole-injecting/transporting performance with electron blocking ability, and that has high stability in the thin-film state and high luminous efficiency, the organic compound being provided as material for an organic electroluminescent device having high efficiency and high durability. The invention also provides a high-efficient, high-durable organic electroluminescent device using the compound. [Means for Resolution] The compound is of the following general formula having a carbazole ring structure. The organic electroluminescent device includes a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, and the compound is used as a constituent material of at least one organic layer. ##STR00001##

Claims

1. A compound of the following general formula (1) having a carbazole ring structure ##STR00039## Wherein: R1 and R2 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, wherein when R2 is a substituted aromatic hydrocarbon, substituted aromatic heterocyclic group, or substituted condensed polycyclic aromatic, the substituent is a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl having 1 to 6 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, linear or branched alkenyl having 2 to 6 carbon atoms, linear or branched alkyloxy having 1 to 6 carbon atoms, cycloalkyloxy having 5 to 10 carbon atoms, phenyl, naphthyl, anthryl, styryl, phenoxy, tolyloxy, benzyloxy, or phenethyloxy, and wherein r1 represents 0 or an integer of 1 to 3, r2 represents 0 or an integer of 1 to 4; A1 represents a monovalent group of the general formula (2) below, A2 represents one of the monovalent groups of the general formulae (3) to (7) below; B represents a divalent group of substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocyclic ring, or a divalent group of substituted or unsubstituted condensed polycyclic aromatic; and C represents a single bond, or a divalent group of substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocyclic ring, or a divalent group of substituted or unsubstituted condensed polycyclic aromatic; where when B represents a divalent group of substituted or unsubstituted aromatic hydrocarbon, C does not represent a single bond; ##STR00040## wherein R3 and R4 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r3 represents 0 or an integer of 1 to 4, r4 represents 0 or an integer of 1 to 3, and Ar1 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, wherein the substituent in the substituted aromatic hydrocarbon, substituted aromatic heterocyclic group, or substituted condensed polycyclic aromatic of Ar1 is a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl having 1 to 6 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, linear or branched alkenyl having 2 to 6 carbon atoms, linear or branched alkyloxy having 1 to 6 carbon atoms, cycloalkyloxy having 5 to 10 carbon atoms, phenyl, naphthyl, anthryl, styryl, phenoxy, tolyloxy, benzyloxy, and phenethyloxy, wherein the substituent may be further substituted and wherein two or more substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; ##STR00041## wherein R5 and R6 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r5 represents 0 or an integer of 1 to 4, r6 represents 0 or an integer of 1 to 5, and Ar2 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic; ##STR00042## wherein R7 and R8 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r7 and r8 may be the same or different, and represent 0 or an integer of 1 to 4; ##STR00043## wherein Ar3 and Ar4 may be the same or different, and represent substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and these groups may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; ##STR00044## wherein R9 and R10 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r9 represents 0 or an integer of 1 to 4, r10 represents 0 or an integer of 1 to 3, Ar5 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and D represents substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom; ##STR00045## wherein R11 and R12 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r11 and r12 may be the same or different, and represent 0 or an integer of 1 to 3, Ar6 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and W, X, Y, and Z represent a carbon atom or a nitrogen atom, where only one of W, X, Y, and Z is a nitrogen atom, and, in this case, the nitrogen atom does not have the substituent R12.

2. The compound having a carbazole ring structure according to claim 1, wherein A2 in the general formula (1) is a monovalent group represented by the general formula (3).

3. The compound having a carbazole ring structure according to claim 1, wherein A2 in the general formula (1) is a monovalent group represented by the general formula (4).

4. The compound having a carbazole ring structure according to claim 1, wherein A2 in the general formula (1) is a monovalent group represented by the general formula (5).

5. The compound having a carbazole ring structure according to claim 4, wherein the compound is of the following general formula (1a) ##STR00046## wherein R1, R2, R3 and R4 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r1 and r4 may be the same or different, and represent 0 or an integer of 1 to 3, r2 and r3 may be the same or different, and represent 0 or an integer of 1 to 4, and Ar1, Ar3, and Ar4 may be the same or different, and represent substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, where Ar3 and Ar4 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring.

6. The compound having a carbazole ring structure according to claim 4, wherein the compound is of the following general formula (1b) ##STR00047## wherein R1, R2, R3 and R4 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r1 and r4 may be the same or different, and represent 0 or an integer of 1 to 3, r2 and r3 may be the same or different, and represent 0 or an integer of 1 to 4, and Ar1, Ar3, and Ar4 may be the same or different, and represent substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, where Ar3 and Ar4 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring.

7. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, characterized in that a compound of the following general formula (1) having a carbazole ring structure is used as a constituent material of at least one organic layer ##STR00048## wherein R1 and R2 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, wherein when R2 is a substituted aromatic hydrocarbon, substituted aromatic heterocyclic group, or substituted condensed polycyclic aromatic, the substituent is a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl having 1 to 6 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, linear or branched alkenyl having 2 to 6 carbon atoms, linear or branched alkyloxy having 1 to 6 carbon atoms, cycloalkyloxy having 5 to 10 carbon atoms, phenyl, naphthyl, anthryl, styryl, phenoxy, tolyloxy, benzyloxy, or phenethyloxy, and wherein r1 represents 0 or an integer of 1 to 3, r2 represents 0 or an integer of 1 to 4, A1 represents a monovalent group of the general formula (2) below, A2 represents one of the monovalent groups of the general formulae (3)to (7) below, B represents a divalent group of substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocyclic ring, or a divalent group of substituted or unsubstituted condensed polycyclic aromatic, and C represents a single bond, or a divalent group of substituted or unsubstituted aromatic hydrocarbon, a divalent group of a substituted or unsubstituted aromatic heterocyclic ring, or a divalent group of substituted or unsubstituted condensed polycyclic aromatic, where when B represents a divalent group of substituted or unsubstituted aromatic hydrocarbon, C does not represent a single bond; ##STR00049## wherein R3 and R4 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r3 represents 0 or an integer of 1 to 4, r4 represents 0 or an integer of 1 to 3, and Ar1 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, wherein the substituent in the substituted aromatic hydrocarbon, substituted aromatic heterocyclic group, or substituted condensed polycyclic aromatic of Ar1 is a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl having 1 to 6 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, linear or branched alkenyl having 2 to 6 carbon atoms, linear or branched alkyloxy having 1 to 6 carbon atoms, cycloalkyloxy having 5 to 10 carbon atoms, phenyl, naphthyl, anthryl, styryl, phenoxy, tolyloxy, benzyloxy, and phenethyloxy, wherein the substituent may be further substituted and wherein two or more substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; ##STR00050## wherein R5 and R6 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r5 represents 0 or an integer of 1 to 4, r6 represents 0 or an integer of 1 to 5, and Ar2 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic; ##STR00051## wherein R7 and R8 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r7 and r8 may be the same or different, and represent 0 or an integer of 1 to 4; ##STR00052## wherein Ar3 and Ar4 may be the same or different, and represent substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and these groups may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; ##STR00053## wherein R9 and R10 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r9 represents 0 or an integer of 1 to 4, r10 represents 0 or an integer of 1 to 3, Ar5 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and D represents substituted or unsubstituted methylene, an oxygen atom or a sulfur atom ##STR00054## wherein R11 and R12 may be the same or different, and represent a deuterium atom, a fluorine atom, a chlorine atom, cyano, nitro, linear or branched alkyl having 1 to 6 carbon atoms that may have a substituent, cycloalkyl having 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl having 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy having 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy having 5 to 10 carbon atoms that may have a substituent, substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted condensed polycyclic aromatic, or substituted or unsubstituted aryloxy, and these substituents may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and wherein r11 and r12 may be the same or different, and represent 0 or an integer of 1 to 3, Ar6 represents substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted aromatic heterocyclic group, or substituted or unsubstituted condensed polycyclic aromatic, and W, X, Y, and Z represent a carbon atom or a nitrogen atom, where only one of W, X, Y, and Z is a nitrogen atom, and, in this case, the nitrogen atom does not have the substituent R12.

8. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole transport layer, and wherein the compound of the general formula (1) is used as at least one constituent material in the hole transport layer.

9. The organic electroluminescent device according to claim 7, wherein the organic layer is an electron blocking layer, and wherein the compound of the general formula (1) is used as at least one constituent material in the electron blocking layer.

10. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole injection layer, and wherein the compound of the general formula (1) is used as at least one constituent material in the hole injection layer.

11. The organic electroluminescent device according to claim 7, wherein the organic layer is a light emitting layer, and wherein the compound of the general formula (1) is used as at least one constituent material in the light emitting layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a 1H-NMR chart of the compound of Example 1 of the present invention (Compound 8).

(2) FIG. 2 is a 1H-NMR chart of the compound of Example 2 of the present invention (Compound 13).

(3) FIG. 3 is a 1H-NMR chart of the compound of Example 3 of the present invention (Compound 14).

(4) FIG. 4 is a 1H-NMR chart of the compound of Example 4 of the present invention (Compound 22).

(5) FIG. 5 is a 1H-NMR chart of the compound of Example 5 of the present invention (Compound 26).

(6) FIG. 6 is a 1H-NMR chart of the compound of Example 6 of the present invention (Compound 38).

(7) FIG. 7 is a diagram illustrating the configuration of the EL devices of Examples 9 to 12 and Comparative Examples 1 and 2.

(8) FIG. 8 is a diagram illustrating the configuration of the EL devices of Examples 13 and 14 and Comparative Example 3.

MODE FOR CARRYING OUT THE INVENTION

(9) The compounds having a carbazole ring structure of the present invention are novel compounds, and may be synthesized, for example, as follows. First, 3-bromo-9-arylcarbazole is synthesized by the bromination of a carbazole substituted with an aryl group at the corresponding ninth position, using, for example, N-bromosuccinimide (see, for example, Non-Patent Document 3). The boronic acid or borate synthesized by the reaction of the resulting bromo compound with compounds such as pinacolborane and bis(pinacolato)diboron (see, for example, Non-Patent Document 4) can then be reacted with various halogeno-9H-carbazoles in a cross-coupling reaction such as Suzuki coupling (see, for example, Non-Patent Document 5) to synthesize (N-aryl-9′H-carbazol-3′-yl)-9H-carbazole. A compound having a carbazole ring structure can then be synthesized by a condensation reaction, such as the Ullmann reaction, between the (N-aryl-9′H-carbazol-3′-yl)-9H-carbazole and aryl halides substituted with various diarylamino groups.

(10) The following presents specific examples of preferred compounds among the compounds of general formula (1) having a carbazole ring structure. The present invention, however, is not restricted to these compounds.

(11) ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036##

(12) These compounds were purified by methods such as column chromatography, adsorption using, for example, a silica gel, activated carbon, or activated clay, and recrystallization or crystallization using a solvent. The compounds were identified by NMR analysis. Glass transition point (Tg) and work function were taken for the measurement of physical properties. Glass transition point (Tg) can be used as an index of stability in the thin-film state, and the work function as an index of hole transportability.

(13) Glass transition point (Tg) was measured using a powder, using a high-sensitive differential scanning calorimeter (DSC3100S produced by Bruker AXS).

(14) For the measurement of work function, a 100 nm-thick thin film was fabricated on an ITO substrate, and an atmosphere photoelectron spectrometer AC-3 produced by Riken Keiki Co., Ltd. was used.

(15) The organic EL device of the present invention may have a structure including an anode, a hole transport layer, an electron blocking layer, a light emitting layer, an electron transport layer, and a cathode successively formed on a substrate, optionally with a hole injection layer between the anode and the hole transport layer, or with an electron injection layer between the electron transport layer and the cathode. In such multilayer structures, some of the organic layers may be omitted. For example, the device may be configured to include an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode successively formed on a substrate.

(16) Electrode materials with a large work function, such as ITO and gold, are used as the anode of the organic EL device of the present invention. The hole injection layer may be made of material such as porphyrin compounds as represented by copper phthalocyanine, starburst-type triphenylamine derivatives, various triphenylamine tetramers, and coating-type polymer materials, in addition to the compounds of general formula (1) having a carbazole ring structure of the present invention. These materials may be formed into a thin film by using a vapor deposition method, or other known methods such as spin coating and an inkjet method.

(17) Examples of the material used for the hole transport layer of the present invention include benzidine derivatives such as N,N′-diphenyl-N,N′-di(m-tolyl)benzidine (hereinafter, simply “TPD”), N,N′-diphenyl-N,N′-di(α-naphthyl)benzidine (hereinafter, simply “NPD”), and N,N,N′,N′-tetrabiphenylylbenzidine, and various triphenylamine trimers and tetramers, in addition to the compounds of general formula (1) having a carbazole ring structure of the present invention. These may be individually deposited for film forming, or may be used as a single layer deposited as a mixture with other materials, or as a laminate of individually deposited layers, a laminate of layers deposited as a mixture, or a laminate of layers deposited by being mixed with an individually deposited layer. Examples of the material used for the hole injection/transport layer include coating-type polymer materials such as poly(3,4-ethylenedioxythiophene) (hereinafter, simply “PEDOT”)/poly(styrene sulfonate) (hereinafter, simply “PSS”). These materials may be formed into a thin-film by using a vapor deposition method, or other known methods such as spin coating and an inkjet method.

(18) Examples of the material used for the electron blocking layer of the present invention include compounds having an electron blocking effect, including, for example, carbazole derivatives such as 4,4′,4″-tri(N-carbazolyl)triphenylamine (hereinafter, simply “TCTA”), 9,9-bis[4-(carbazol-9-yl) phenyl]fluorene, and 1,3-bis(carbazol-9-yl)benzene (hereinafter, simply “mCP”); and compounds having a triphenylsilyl group and a triarylamine structure, as represented by 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9 H-fluorene, in addition to the compounds of general formula (1) having a carbazole ring structure of the present invention.

(19) Examples of the material used for the light emitting layer of the present invention include various metal complexes, anthracene derivatives, bis(styryl)benzene derivatives, pyrene derivatives, oxazole derivatives, and polyparaphenylene vinylene derivatives, in addition to quinolinol derivative metal complexes such as Alq.sub.3. Further, the light emitting layer may be configured from a host material and a dopant material. Examples of the host material include thiazole derivatives, benzimidazole derivatives, and polydialkyl fluorene derivatives, in addition to the foregoing light-emitting materials, and the compounds of general formula (1) having a carbazole ring structure of the present invention. Examples of the dopant material include quinacridone, coumalin, rubrene, perylene, derivatives thereof, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives. These may be individually deposited for film forming, or may be used as a single layer deposited as a mixture with other materials, or as a laminate of individually deposited layers, a laminate of layers deposited as a mixture, or a laminate of layers deposited by being mixed with an individually deposited layer. These materials may be formed into a thin-film by using a vapor deposition method, or other known methods such as spin coating and an inkjet method.

(20) Further, the light-emitting materials may be phosphorescent materials. Examples of phosphorescent materials include green phosphorescent materials such as Ir(ppy).sub.3, blue phosphorescent materials such as FIrpic and FIr6, and red phosphorescent materials such as Btp.sub.2Ir(acac). Here, the compounds of general formula (1) having a carbazole ring structure of the present invention may be used as the hole injecting and transporting host material, in addition to carbazole derivatives such as 4,4′-di(N-carbazolyl)biphenyl (hereinafter, simply “CBP”), TCTA, and mCP. Compounds such as 2,2′,2″-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter, simply “TPBI”) may be used as the electron transporting host material to produce a high-performance organic EL device.

(21) Examples of the hole blocking layer of the present invention include various rare earth complexes, triazole derivatives, triazine derivatives, and oxadiazole derivatives, in addition to phenanthroline derivatives (such as bathocuproin (hereinafter, simply “BCP”)), and quinolinol derivative metal complexes. These materials may also be used as the material of the electron transport layer.

(22) Examples of the electron transport layer of the present invention include various metal complexes, triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline, derivatives, phenanthroline derivatives, and silole derivatives, in addition to quinolinol derivative metal complexes such as Alq.sub.3. These may be individually deposited for film forming, or may be used as a single layer deposited as a mixture with other materials, or as a laminate of individually deposited layers, a laminate of layers deposited as a mixture, or a laminate of layers deposited by being mixed with an individually deposited layer. These materials may be formed into a thin-film by using a vapor deposition method, or other known methods such as spin coating and an inkjet method.

(23) Examples of the electron injection layer of the present invention include alkali metal salts such as lithium fluoride, and cesium fluoride, alkali-earth metal salts such as magnesium fluoride, and metal oxides such as aluminum oxide.

(24) The cathode of the present invention may be made of electrode materials having a low work function (such as aluminum), or alloys of electrode materials having an even lower work function (such as a magnesium-silver alloy, a magnesium-indium alloy, and an aluminum-magnesium alloy).

(25) The following describes an embodiment of the present invention in more detail based on Examples. The present invention, however, is not restricted to the following Examples.

EXAMPLE 1

Synthesis of diphenyl-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]amine (Compound 8)

(26) 3-Bromo-9H-carbazole (3.6 g), 9-phenyl-3-(4,4,5,5-tetramethyl-[1,3,2]dioxabororan-2-yl)-9H-carbazole (6.0 g), toluene (40 ml), ethanol (10 ml), and a 2M potassium carbonate aqueous solution (11 ml) were added to a nitrogen-substituted reaction vessel, and aerated with nitrogen gas for 30 min under ultrasonic waves. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.85 g), and stirred at 74° C. for 3.5 hours. After adding toluene (100 ml), the mixture was heated, and further stirred at 80° C. for 1 hour. The mixture was then cooled to 50° C., and the insolubles were removed by filtration. The filtrate was then concentrated under reduced pressure to obtain a yellowish white crude product. Toluene (300 ml) was added to dissolve the crude product, and the solution was subjected to adsorptive purification with a NH silica gel (16.11 g), and concentrated under reduced pressure to obtain a white powder. The white powder was then purified by being dispersed and washed in ethyl acetate (35 ml) under heat to obtain a white powder of 9-phenyl-9H,9′H-[3,3′]bicarbazolyl (1.96 g; yield 32.7%).

(27) 9-Phenyl-9H,9′H-[3,3′]bicarbazolyl (1.80 g) N-(4′-iodo-biphenyl-4-yl)-diphenylamine (1.88 g), sodium bisulfite (0.07 g), a copper powder (0.013 g), 3,5-di(tert-butyl)salicylic acid (0.05 g), potassium carbonate (0.87 g), and dodecylbenzene (20 ml) were added to a nitrogen-substituted reaction vessel, heated, and stirred at 210° C. for 4 hours. The mixture was cooled to 90° C., extracted with toluene (30 ml), concentrated under reduced pressure, and crystallized from n-hexane (20 ml). As a result, a pale yellowish white powder was obtained. The pale yellowish white powder was then purified twice by recrystallization using toluene/methanol to obtain a white powder of diphenyl-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]amine (Compound 8; 2.34 g; yield 76.5%).

(28) The structure of the resulting white powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 1.

(29) 1H-NMR (THF-d.sub.8) detected 37 hydrogen signals, as follows. δ(ppm)=8.56(2H), 8.27(2H), 7.91(2H), 7.82(2H), 7.65-7.71(8H), 7.47-7.65(4H), 7.37-7.42(3H), 7.25-7.29(6H), 7.13-7.17(6H), 7.03(2H).

EXAMPLE 2

Synthesis of biphenyl-4-yl-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]-phenylamine (Compound 13)

(30) 9-(4-Bromophenyl)-9′-phenyl-9H,9′H-[3,3′]bicarbazolyl (11 g), biphenyl-4-yl-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxabororan-2-yl)phenyl]-phenylamine (9 g), toluene (130 ml), ethanol (30 ml), and a 2M potassium carbonate aqueous solution (30 ml) were added to a nitrogen-substituted reaction vessel, and aerated with nitrogen gas for 30 min under ultrasonic waves. The mixture was heated after adding triphenylphosphine (0.67 g), and stirred at 70° C. for 6 hours. The organic layer was collected after cooling the mixture to room temperature, and washed with saturated brine (100 ml), dehydrated with magnesium sulfate, and concentrated under reduced pressure to obtain a crude product. The crude product was then purified by silica gel column chromatography to obtain a white powder of biphenyl-4-yl-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]-phenylamine (Compound 13; 14.6 g; yield 74%).

(31) The structure of the resulting white powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 2.

(32) 1H-NMR (THF-d.sub.8) detected 41 hydrogen signals, as follows. δ(ppm)=8.57(2H), 8.27(2H), 7.92(2H), 7.83(2H), 7.18-7.72(32H), 7.06(1H).

EXAMPLE 3

Synthesis of bis(biphenyl-4-yl)-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]amine (Compound 14)

(33) 9-(4-Bromophenyl)-9′-phenyl-9H,9′H-[3,3′]bicarbazolyl (11 g), bis(biphenyl-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxabororan-2-yl)phenyl]amine (12 g), toluene (140 ml), ethanol (35 ml), and a 2M potassium carbonate aqueous solution (29 ml) were added to a nitrogen-substituted reaction vessel, and aerated with nitrogen gas for 30 min under ultrasonic waves. The mixture was heated after adding triphenylphosphine (0.68 g), and stirred at 70° C. for 8 hours. The organic layer was collected after cooling the mixture to room temperature, washed with saturated brine (150 ml), dehydrated with magnesium sulfate, and concentrated under reduced pressure to obtain a crude product. The crude product was then purified by silica gel column chromatography to obtain a white powder of bis(biphenyl-4-yl)-[4′-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)biphenyl-4-yl]amine (Compound 14; 12.2 g; yield 71%).

(34) The structure of the resulting white powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 3.

(35) 1H-NMR (THF-d.sub.8) detected 45 hydrogen signals, as follows. δ(ppm)=8.57(2H), 8.27(2H), 7.92(2H), 7.82(2H), 7.24-7.63(37H).

EXAMPLE 4

Synthesis of diphenyl-[2-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)9,9-dimethylfluoren-7-yl]amine (Compound 22)

(36) 9-Phenyl-9H,9′H-[3,3′]bicarbazolyl (1.0 g), N-(2-bromo-9,9-dimethylfluoren-7-yl)-diphenylamine (1.08 g), sodium bisulfite (0.04 g), a copper powder (0.008 g), 3,5-di(tert-butyl)salicylic acid (0.031 g), potassium carbonate (0.51 g), and dodecylbenzene (5 ml) were added to a nitrogen-substituted reaction vessel, heated, and stirred at 215° C. for 11 hours. The mixture was cooled to 100° C., extracted with toluene (50 ml), concentrated under reduced pressure, and crystallized from n-hexane (10 ml). As a result, a brown crude crystal was obtained. Toluene (30 ml) was added to dissolve the crude crystal, and the mixture was subjected to adsorptive purification twice using silica gel (8.7 g) to obtain a dark brown crude product. The crude product was dispersed and washed in an ethyl acetate/n-hexane mixed solvent, and then in ethyl acetate, and crystallized with a toluene/methanol mixed solvent to obtain a white powder. The resulting powder was dispersed and washed in ethyl acetate, and then in methanol, and dried under reduced pressure to obtain a white powder of diphenyl-[2-(9′-phenyl-9H,9′H-[3,3′]bicarbazolyl-9-yl)9,9-dimethylfluoren-7-yl]amine (Compound 22; 0.87 g; yield 46.3%).

(37) The structure of the resulting white powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 4.

(38) 1H-NMR (THF-d.sub.8) detected 41 hydrogen signals, as follows. δ(ppm)=8.53(2H), 8.23(2H), 7.90(1H), 7.78(2H), 7.67-7.71(2H), 7.60-7.62(4H), 7.33-7.55(8H), 7.26(1H), 7.20-7.24(6H), 7.10(4H), 6.96-7.03(3H), 1.47(6H).

EXAMPLE 5

Synthesis of diphenyl-[4′-{3-[(diphenylamino)phenyl-4-yl]-9H-carbazolyl-9-yl}biphenyl-4-yl]amine (Compound 26)

(39) 3-[(Diphenylamino)phenyl-4-yl]-9H-carbazole (1.5 g), N-(4′-iodo-biphenyl-4-yl)-diphenylamine (1.63 g), sodium bisulfite (0.06 g), a copper powder (0.012 g), 3,5-di(tert-butyl)salicylic acid (0.05 g), potassium carbonate (0.76 g), and dodecylbenzene (10 ml) synthesized in the same manner as in Example 1 were added to a nitrogen-substituted reaction vessel, heated, and stirred at 205° C. for 6.5 hours. The mixture was cooled to 90° C., extracted with toluene (50 ml), concentrated under reduced pressure, and crystallized from n-hexane (30 ml). As a result, a pale yellow crude product was obtained. The crude product was recrystallized with an ethyl acetate/n-hexane mixed solvent, dispersed and washed in ethyl acetate, and then in methanol to obtain a white powder of diphenyl-[4′-{3-[(diphenylamino)phenyl-4-yl]-9H-carbazolyl-9-yl}biphenyl-4-yl]amine (Compound 26; 2.16 g; yield 81.2%).

(40) The structure of the resulting white powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 5.

(41) 1H-NMR (THF-d.sub.8) detected 39 hydrogen signals, as follows. δ(ppm)=8.43(1H), 8.22(1H), 7.89(2H), 7.64-7.68(7H), 7.46-7.53(2H), 7.39(1H), 7.24-7.29(9H), 7.11-7.17(12H), 6.98-7.05(4H)

EXAMPLE 6

Synthesis of diphenyl-[2-{3-[(diphenylamino)phenyl-4-yl]-9H-carbazolyl-9-yl}-9,9-dimethylfluoren-7-yl]amine (Compound 38)

(42) 3-[(Diphenylamino)phenyl-4-yl]-9H-carbazole (1.03 g), N-(2-bromo-9,9-dimethylfluoren-7-yl)-diphenylamine (1.1 g), sodium bisulfite (0.04 g), a copper powder (0.008 g), 3,5-di(tert-butyl)salicylic acid (0.031 g), potassium carbonate (0.52 g), and dodecylbenzene (8 ml) synthesized in the same manner as in Example 1 were added to a nitrogen-substituted reaction vessel, heated, and stirred at 210 to 215° C. for 26 hours. The mixture was cooled to 90° C., extracted with toluene (30 ml), and concentrated under reduced pressure to obtain a red brown crude product. The crude product was purified by silica gel column chromatography, crystallized with an ethyl acetate/n-hexane mixed solvent, and dispersed and washed in methanol to obtain a pale yellow powder of diphenyl-[2-{3-[(diphenylamino)phenyl-4-yl]-9H-carbazolyl-9-yl}-9,9-dimethylfluoren-7-yl]amine (Compound 38; 1.49 g; yield 77.6%).

(43) The structure of the resulting pale yellow powder was identified by NMR. The 1H-NMR measurement result is presented in FIG. 6.

(44) 1H-NMR (THF-d.sub.8) detected 43 hydrogen signals, as follows. δ(ppm)=8.43(1H), 8.22(1H), 7.93(1H), 7.65-7.73(5H), 7.55(1H), 7.48(1H), 7.45(1H), 7.38(1H), 7.23-7.30(10H), 7.11-7.17(10H), 7.06(1H), 6.98-7.02(4H), 1.50(6H)

EXAMPLE 7

(45) The glass transition points of the compounds of the present invention were determined using a high-sensitive differential scanning calorimeter (DSC 3100S produced by Bruker AXS).

(46) TABLE-US-00001 Glass transition point Compound of Example 1 of the present invention 137° C. Compound of Example 2 of the present invention 144° C. Compound of Example 3 of the present invention 158° C. Compound of Example 4 of the present invention 152° C. Compound of Example 5 of the present invention 126° C. Compound of Example 6 of the present invention 137° C.

(47) The compounds of the present invention have glass transition points of 100° C. or higher, demonstrating that the compounds of the present invention have a stable thin-film state.

EXAMPLE 8

(48) A 100 nm-thick vapor-deposited film was fabricated on an ITO substrate using the compounds of the present invention, and the work function was measured using an atmospheric photoelectron spectrometer (Model AC-3 produced by Riken Keiki Co., Ltd.).

(49) TABLE-US-00002 Work function Compound of Example 1 of the present invention 5.54 eV Compound of Example 2 of the present invention 5.53 eV Compound of Example 3 of the present invention 5.54 eV Compound of Example 4 of the present invention 5.51 eV Compound of Example 5 of the present invention 5.55 eV Compound of Example 6 of the present invention 5.53 eV

(50) As the results show, the compounds of the present invention have desirable energy levels compared to the work function 5.4 eV of common hole transport materials such as NPD and TPD, and thus possess desirable hole transportability.

EXAMPLE 9

(51) The organic EL device, as illustrated in FIG. 7, was fabricated from a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 7, an electron injection layer 8, and a cathode (aluminum electrode) 9 successively formed by vapor deposition on a glass substrate 1 that had been provided beforehand with an ITO electrode as a transparent anode 2.

(52) Specifically, the glass substrate 1 having ITO (thickness 150 nm) formed thereon was washed with an organic solvent, and subjected to an oxygen plasma treatment to wash the surface. The glass substrate with the ITO electrode was then installed in a vacuum vapor deposition apparatus, and the pressure was reduced to 0.001 Pa or less. This was followed by formation of the hole injection layer 3 by forming Compound 86 of the structural formula below over the transparent anode 2 in a thickness of 20 nm. The hole transport layer 4 was then formed on the hole injection layer 3 by forming the compound of Example 1 of the present invention (Compound 8) in a thickness of 40 nm. Thereafter, the light emitting layer 5 was formed on the hole transport layer 4 by forming Compounds 87 and 88 of the structural formulae below in a thickness of 30 nm using dual vapor deposition at a deposition rate ratio of compound 87:compound 88=5:95. The electron transport layer 7 was then formed on the light emitting layer 5 by forming Alq.sub.3 in a thickness of 30 nm. Then, the electron injection layer 8 was formed on the electron transport layer 7 by forming lithium fluoride in a thickness of 0.5 nm. Finally, the cathode 9 was formed by vapor depositing aluminum in a thickness of 150 nm. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature.

(53) Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device fabricated with the compound of Example 1 of the present invention (Compound 8).

(54) ##STR00037##

EXAMPLE 10

(55) An organic EL device was fabricated under the same conditions used in Example 9, except that the compound of Example 4 of the present invention (Compound 22) was used as the material of the hole transport layer 4 of Example 9. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

EXAMPLE 11

(56) An organic EL device was fabricated under the same conditions used in Example 9, except that the compound of Example 5 of the present invention (Compound 26) was used as the material of the hole transport layer 4 of Example 9. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

EXAMPLE 12

(57) An organic EL device was fabricated under the same conditions used in Example 9, except that the compound of Example 6 of the present invention (Compound 38) was used as the material of the hole transport layer 4 of Example 9. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

COMPARATIVE EXAMPLE 1

(58) For comparison, an organic EL device was fabricated under the same conditions used in Example 9, except that the Compound B was used as the material of the hole transport layer 4 of Example 9. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

COMPARATIVE EXAMPLE 2

(59) For comparison, an organic EL device was fabricated under the same conditions used in Example 9, except that the compound 89 of the following structural formula was used as the material of the hole transport layer 4 of Example 9. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

(60) ##STR00038##

(61) TABLE-US-00003 TABLE 1 Luminous Power Voltage Luminance current efficiency [V] [cd/m.sup.2] efficiency [lm/W] (@10 (@10 [cd/A] (@10 (@10 Compound mA/cm.sup.2) mA/cm.sup.2) mA/cm.sup.2) mA/cm.sup.2) Ex. 9  Compound 8  4.70 805 8.06 5.39 Ex. 10 Compound 22 4.87 993 9.94 6.41 Ex. 11 Compound 26 5.27 954 9.55 5.69 Ex. 12 Compound 38 5.08 1032 10.34 6.40 Com. Compound B 5.62 908 9.07 5.06 Ex. 1  Com. Compound 89 4.87 783 7.84 5.06 Ex. 2 

(62) As can be seen in Table 1, the driving voltage upon passing a current with a current density of 10 mA/cm.sup.2 was 4.70 V with the compound of Example 1 of the present invention (Compound 8), lower than 5.62 V with Compound B and 4.87 V with Compound 89. The compounds of Examples 4 to 6 (Compounds 22, 26, 38) also had lower voltages than Compound B. The compound of Example 1 (Compound 8) of the present invention also had an improved power efficiency of 5.39 lm/W over 5.06 lm/W (Compound B) and 5.06 lm/W (Compound 89). The compounds of Examples 4 to 6 (Compounds 22, 26, 38) had even greater power efficiencies of 5.69 to 6.41 lm/W.

(63) As these results clearly demonstrate, the organic EL devices using the compounds having a carbazole ring structure of the present invention can have improved power efficiency and lower actual driving voltage compared to the organic EL device using the known Compound B.

(64) The results of turn on voltage measurements using the foregoing organic EL devices are presented below.

(65) TABLE-US-00004 Turn on Organic EL device Compound voltage [V] Example 9 Compound 8  2.7 Comparative Example 1 Compound B 2.9 Comparative Example 2 Compound 89 2.8

(66) It can be seen that the turn on voltage was lower in Example 9 than in Comparative Examples 1 and 2 in which Compound B and Compound 89 were used, respectively.

EXAMPLE 13

(67) An organic EL device, as illustrated in FIG. 8, was fabricated from a hole transport layer 4, a light emitting layer 5, a hole blocking layer 6, an electron transport layer 7, an electron injection layer 8, and a cathode (aluminum electrode) 9 successively formed by vapor deposition on a glass substrate 1 that had been provided with an ITO electrode as a transparent anode 2.

(68) Specifically, the glass substrate 1 having ITO (thickness 150 nm) formed thereon was washed with an organic solvent, and subjected to an oxygen plasma treatment to wash the surface. The glass substrate with the ITO electrode was then installed in a vacuum vapor deposition apparatus, and the pressure was reduced to 0.001 Pa or less. This was followed by formation of the hole transport layer 4 by forming the compound of Example 1 of the present invention (Compound 8) over the transparent anode 2 in a thickness of 50 nm. Thereafter, the light emitting layer 5 was formed on the hole transport layer 4 by forming TPBI and Ir(ppy).sub.3 in a thickness of 20 nm using dual vapor deposition at a deposition rate that makes the TPBI:Ir(ppy).sub.3 composition ratio 92:8. The hole blocking layer 6 was then formed on the light emitting layer 5 by forming BCP in a thickness of 10 nm. This was followed by formation of the electron transport layer 7 by forming Alq.sub.3 on the hole blocking layer 6 in a thickness of 30 nm. Then, the electron injection layer 8 was formed on the electron transport layer 7 by forming lithium fluoride in a thickness of 0.5 nm. Finally, the cathode 9 was formed by vapor depositing aluminum in a thickness of 150 nm. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature.

(69) Table 2 summarizes the results of the emission characteristics measurements performed by passing a current of a 10 mA/cm.sup.2 current density through the organic EL device fabricated with the compound 8 of Example 1 of the present invention.

EXAMPLE 14

(70) An organic EL device was fabricated under the same conditions used in Example 13, except that the compound of Example 6 of the present invention (Compound 38) was used as the material of the hole transport layer 4 of Example 13. The characteristics of the organic EL device thus fabricated were measured in an atmosphere at ordinary temperature. Table 2 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device thus fabricated.

COMPARATIVE EXAMPLE 3

(71) For comparison, an organic EL device was fabricated under the same conditions used in Example 13, except that the Compound 89 was used as the material of the hole transport layer 4 of Example 13. Table 2 summarizes the results of the emission characteristics measurements performed by passing a current with a current density of 10 mA/cm.sup.2 through the organic EL device thus fabricated.

(72) TABLE-US-00005 TABLE 2 Luminous Power Voltage Luminance current efficiency [V] [cd/m.sup.2] efficiency [lm/W] (@10 (@10 [cd/A] (@10 (@10 Compound mA/cm.sup.2) mA/cm.sup.2) mA/cm.sup.2) mA/cm.sup.2) Ex. 13 Compound 8 5.35 3112 31.17 18.30 Ex. 14 Compound 38 5.30 2830 28.34 16.82 Com. Compound 89 5.89 1896 18.98 10.13 Ex. 3 

(73) As can be seen in Table 2, the driving voltage upon passing a current with a current density of 10 mA/cm.sup.2 was 5.35 V with the compound of Example 1 of the present invention (Compound 8), and 5.30 V with the compound of Example 6 (Compound 38), lower than 5.89 V with Compound 89. The compound of Example 1 of the present invention (Compound 8) and the compound of Example 6 (Compound 38) also had greatly improved power efficiencies of 18.30 lm/W and 16.82 lm/W, respectively, over the power efficiency 10.13 lm/W of Compound 89.

(74) As these results clearly demonstrate, the phosphorescent organic EL devices using the compounds having a carbazole ring structure of the present invention can have improved power efficiency and lower actual driving voltage compared to the phosphorescent organic EL device using the known Compound 89.

INDUSTRIAL APPLICABILITY

(75) The compound having a carbazole ring structure of the present invention has good hole transportability, excels in electron blocking ability, and thus has a stable thin-film state. The compound is therefore excellent as a compound for organic EL devices. The organic EL device fabricated with the compound can have high luminous efficiency and high power efficiency, and can have a low actual driving voltage to improve durability. There are potential applications for, for example, home electronic appliances and illuminations.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

(76) 1 Glass substrate 2 Transparent anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode