Compound having acridan ring structure, and organic electroluminescent device

Abstract

An organic compound with characteristics excelling in hole-injecting/transporting performance and having an electron blocking ability, a highly stable thin-film state, and excellent heat resistance is provided as material for an organic electroluminescent device of high efficiency and high durability, and the organic electroluminescent device of high efficiency and high durability is provided using this compound. The compound of a general formula (Chemical Formula 1) having a substituted acridan ring structure is used as a constituent material of at least one organic layer in the organic electroluminescent device that includes a pair of electrodes and one or more organic layers sandwiched between the pair of electrodes. ##STR00001##

Claims

1. A compound of the following general formula (2) having an acridan ring structure, ##STR00036## wherein A represents a divalent group of a 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 aromatics; Ar.sub.1 is substituted or unsubstituted phenyl or substituted or unsubstituted biphenyl, Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.3 represents a substituted or unsubstituted phenyl group; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 R.sub.6 and R.sub.7 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy of 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, which 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 R.sub.8 and R.sub.9 represent methyl.

2. A compound of the following general formula (3) having an acridan ring structure, ##STR00037## wherein Ar.sub.1 is substituted or unsubstituted phenyl or substituted or unsubstituted biphenyl, Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.3 represents a substituted or unsubstituted phenyl group; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 R.sub.6, R.sub.7 and R.sub.10 to R.sub.13 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6 carbon atoms that may have a sub stituent, linear or branched alkyloxy of 1 to 6carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, where R.sub.1 and R.sub.2, R.sub.2 and R.sub.3, R.sub.3 and R.sub.4, R.sub.6 and R.sub.7, R.sub.10 and R.sub.11, and R.sub.12 and R.sub.13 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 R.sub.8 and R.sub.9-represent methyl.

3. A compound of the following general formula (4) having an acridan ring structure, ##STR00038## wherein A represents a divalent group of a 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 aromatics; Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.3 represents a substituted or unsubstituted phenyl group; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 R.sub.6, R.sub.7 and R.sub.14 to R.sub.18 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6carbon atoms that may have a substituent, linear or branched alkyloxy of 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, where R.sub.1 and R.sub.2, R.sub.2 and R.sub.3, R.sub.3 and R.sub.4, R.sub.6 and R.sub.7, R.sub.14 and R.sub.15, and R.sub.15 and R.sub.16, R.sub.16 and R.sub.17, and R.sub.17 and R.sub.18 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 R.sub.8 and R.sub.9 represent methyl.

4. The compound having an acridan ring structure according to claim 2, wherein the compound is represented by the following general formula (4′), [Chemical Formula 4′] ##STR00039## wherein Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.3 represents a substituted or unsubstituted phenyl group; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 R.sub.6, R.sub.7, R.sub.10 to R.sub.13, R.sub.14, R.sub.15, R.sub.17, and R.sub.18 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy of 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, where R.sub.1 and R.sub.2, R.sub.2 and R.sub.3, R.sub.3 and R.sub.4, R.sub.6 and R.sub.7, R.sub.10 and R.sub.11, R.sub.12 and R.sub.13, R.sub.14 and R.sub.15, and R.sub.17 and R.sub.18 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 R.sub.8 and R.sub.9 represent methyl.

5. The compound having an acridan ring structure according to claim 3, wherein the compound is represented by the following general formula (4″′), ##STR00040## wherein Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 to R.sub.7, R.sub.10 to R.sub.13, and R.sub.14 to R.sub.18 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6carbon atoms that may have a substituent, linear or branched alkyloxy of 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, where R.sub.1 and R.sub.2, R.sub.6 and R.sub.7, R.sub.10 and R.sub.11, R.sub.12 and R.sub.13, R.sub.14 and R.sub.15, R.sub.15 and R.sub.16, R.sub.16 and R.sub.17, and R.sub.17 and R.sub.18 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 R.sub.8 and R.sub.9 represent methyl.

6. The compound having an acridan ring structure according to claim 3, wherein the compound is represented by the following general formula (4″″), ##STR00041## wherein Ar.sub.2 and Ar.sub.3 may be the same or different, and represent a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group, where Ar.sub.2 and Ar.sub.3 may directly bind to each other via a single bond or via substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring, and substituents of Ar.sub.2 and Ar.sub.3 may bind to each other via a single bond, substituted or unsubstituted methylene, an oxygen atom, or a sulfur atom to form a ring; R.sub.1, R.sub.2 and R.sub.4 are hydrogen; R.sub.5 to R.sub.7, R.sub.10 to R.sub.13, R.sub.14, R.sub.15, R.sub.17, and R.sub.18 may be the same or different, and represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, cyano, trifluoromethyl, nitro, linear or branched alkyl of 1 to 6 carbon atoms that may have a substituent, cycloalkyl of 5 to 10 carbon atoms that may have a substituent, linear or branched alkenyl of 2 to 6 carbon atoms that may have a substituent, linear or branched alkyloxy of 1 to 6 carbon atoms that may have a substituent, cycloalkyloxy of 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or substituted or unsubstituted aryloxy, where R.sub.1 and R.sub.2, R.sub.6 and R.sub.7, R.sub.10 and R.sub.11 , R.sub.12 and R.sub.13, R.sub.14 and R.sub.15, and R.sub.17 and R.sub.18 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 R.sub.8 and R.sub.9 represent methyl.

7. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 1 is used as a constituent material of at least one organic layer.

8. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole transport layer.

9. The organic electroluminescent device according to claim 7, wherein the organic layer is an electron blocking layer.

10. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole injection layer.

11. The organic electroluminescent device according to claim 7, wherein the organic layer is a light emitting layer.

12. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 2 is used as a constituent material of at least one organic layer.

13. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 3 is used as a constituent material of at least one organic layer.

14. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 4 is used as a constituent material of at least one organic layer.

15. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 5 is used as a constituent material of at least one organic layer.

16. An organic electroluminescent device that comprises a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, wherein the compound having an acridan ring structure of claim 6 is used as a constituent material of at least one organic 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 11).

(2) FIG. 2 is a 1H-NMR chart of the compound of Example 2 of the present invention (Compound 19).

(3) FIG. 3 is a 1H-NMR chart of the compound of Example 3 of the present invention (Compound 27).

(4) FIG. 4 is a 1H-NMR chart of the compound of Example 4 of the present invention (Compound 12).

(5) FIG. 5 is a 1H-NMR chart of the compound of Example 5 of the present invention (Compound 13).

(6) FIG. 6 is a 1H-NMR chart of the compound of Example 6 of the present invention (Compound 24).

(7) FIG. 7 is a 1H-NMR chart of the compound of Example 7 of the present invention (Compound 23).

(8) FIG. 8 is a diagram illustrating the configuration of the EL devices of Examples 10 and 11 and Comparative Example 1.

MODE FOR CARRYING OUT THE INVENTION

(9) The compounds having an acridan ring structure of the present invention are novel compounds, and may be synthesized, for example, as follows. First, 2-bromo-10-arylacridan is synthesized by bromination of acridan substituted with an aryl group at the corresponding tenth position, using bromine, N-bromosuccinimide, or the like (refer to Patent Document 3, for example). Boronic acid or borate synthesized by the reaction of the resulting bromo compound with compounds such as pinacolborane and bis(pinacolato)diboron (refer to Non-Patent Document 4, for example) can then be reacted with aryl halides substituted with various diarylamino groups in a cross-coupling reaction such as Suzuki coupling (refer to Non-Patent Document 5, for example) to synthesize the compounds having an acridan ring structure.

(10) The compounds having an acridan ring structure of the present invention may be synthesized also by using the following method. First, acridan substituted with an arylamino group at the corresponding second position can be reacted with various aryl halides in a cross-coupling reaction such as Ullmann coupling (refer to Non-Patent Document 6, for example), and the compounds having an acridan ring structure can then be synthesized.

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

(12) ##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032## ##STR00033##

(13) These compounds were purified by methods such as column chromatography, adsorption using, for example, silica gel, activated carbon, or activated clay, and recrystallization or crystallization using a solvent. The compounds were identified by an NMR analysis. A glass transition point (Tg), a melting point, and a work function were measured as material property values. The glass transition point (Tg) can be used as an index of stability in the thin-film state, the melting point as an index of vapor deposition, and the work function as an index of hole transportability.

(14) The glass transition point (Tg) and the melting point were measured by a high-sensitive differential scanning calorimeter (DSC3100S produced by Bruker AXS) using powder.

(15) For the measurement of the 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.

(16) 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.

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

(18) Examples of material used for the hole transport layer of the organic EL device of the present invention can be benzidine derivatives such as N,N′-diphenyl-N,N′-di(m-tolyl)benzidine (hereinafter referred to as TPD), N,N′-diphenyl-N,N′-di(α-naphthyl)benzidine (hereinafter referred to as NPD), and N,N,N′,N′-tetrabiphenylylbenzidine; 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter referred to as TAPC); and various triphenylamine trimers and tetramers, in addition to the compounds of general formula (1) having an acridan ring structure of the present invention. These may be individually deposited for film forming, may be used as a single layer deposited mixed with other materials, or may be formed as a laminate of individually deposited layers, a laminate of mixedly deposited layers, or a laminate of the individually deposited layer and the mixedly deposited layer. Examples of material used for the hole injection/transport layer can be coating-type polymer materials such as poly(3,4-ethylenedioxythiophene) (hereinafter referred to as PEDOT)/poly(styrene sulfonate) (hereinafter referred to as PSS). These materials may be formed into, a thin-film by a vapor deposition method or other known methods such as a spin coating method and an inkjet method.

(19) Further, material used for the hole injection layer or the hole transport layer may be obtained by p-doping trisbromophenylamine hexachloroantimony or the like into the material commonly used for these layers, or may be, for example, polymer compounds each having a TPD structure as a part of the compound structure.

(20) Examples of material used for the electron blocking layer of the organic EL device of the present invention can be compounds having an electron blocking effect, including, for example, carbazole derivatives such as 4,4′,4″-tri(N-carbazolyl)triphenylamine (hereinafter referred to as TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (hereinafter referred to as mCP), and 2,2-bis(4-carbazol-9-ylphenyl)adamantane (hereinafter referred to as Ad-Cz); and compounds having a triphenylsilyl group and a triarylamine structure, as represented by 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene, in addition to the compounds of general formula (1) having an acridan ring structure of the present invention. These may be individually deposited for film forming, may be used as a single layer deposited mixed with other materials, or may be formed as a laminate of individually deposited layers, a laminate of mixedly deposited layers, or a laminate of the individually deposited layer and the mixedly deposited layer. These materials may be formed into a thin-film by using a vapor deposition method or other known methods such as a spin coating method and an inkjet method.

(21) Examples of material used for the light emitting layer of the organic EL device of the present invention can be 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 comprise a host material and a dopant material. Examples of the host material can be thiazole derivatives, benzimidazole derivatives, and polydialkyl fluorene derivatives, in addition to the above light-emitting materials and the compounds of general formula (1) having an acridan ring structure of the present invention. Examples of the dopant material can be quinacridone, coumarin, rubrene, perylene, derivatives thereof, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives. These may be individually deposited for film forming, may be used as a single layer deposited mixed with other materials, or may be formed as a laminate of individually deposited layers, a laminate of mixedly deposited layers, or a laminate of the individually deposited layer and the mixedly deposited layer.

(22) Further, the light-emitting material may be a phosphorescent light-emitting material. Phosphorescent materials as metal complexes of metals such as iridium and platinum may be used as the phosphorescent light-emitting material. Examples of the phosphorescent materials can be green phosphorescent materials, such as Ir(ppy).sub.3, blue phosphorescent materials such as FIrpic and FIr.sub.6, and red phosphorescent materials such as Btp.sub.2Ir(acac). As the hole injecting and transporting host material, the compounds of general formula (1) having an acridan ring structure of the present invention may be used in addition to carbazole derivatives such as 4,4′-di(N-carbazolyl)biphenyl (hereinafter referred to as CBP), TCTA, and mCP. Compounds such as p-bis(triphenylsilyl)benzene (hereinafter referred to as UGH2) and 2,2′,2″-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter referred to as TPBI) may be used as the electron transporting host material to produce a high-performance organic EL device.

(23) In order to avoid concentration quenching, it is preferable to dope the host material with the phosphorescent light-emitting material by co-evaporation in a range of 1 to 30 weight percent to the whole light emitting layer.

(24) These materials may be formed into a thin-film by using a vapor deposition method or other known methods such as a spin coating method and an inkjet method.

(25) The hole blocking layer of the organic EL device of the present invention may be formed by using hole blocking compounds such as various rare earth complexes, triazole derivatives, triazine derivatives, and oxadiazole derivatives, in addition to the metal complexes of phenanthroline derivatives such as bathocuproin (hereinafter referred to as BCP), and the metal complexes of quinolinol derivatives such as aluminum(III) bis(2-methyl-8-quinolinate)-4-phenylphenolate (hereinafter referred to as BAlq). These materials may also serve as the material of the electron transport layer. These may be individually deposited for film forming, may be used as a single layer deposited mixed with other materials, or may be formed as a laminate of individually deposited layers, a laminate of mixedly deposited layers, or laminate of the individually deposited layer and the mixedly deposited layer. These materials may be formed into a thin-film by using a vapor deposition method or other known methods such as a spin coating method and an inkjet method.

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

(27) Examples of material used for the electron injection layer of the organic EL device of the present invention can be alkali metal salts such as lithium fluoride and cesium fluoride; alkaline earth metal salts such as magnesium fluoride; and metal oxides such as aluminum oxide. However, the electron injection layer may be omitted in the preferred selection of the electron transport layer and the cathode.

(28) The cathode of the organic EL device of the present invention may be made of an electrode material with a low work function such as aluminum, or an alloy of an electrode material with an even lower work function such as a magnesium-silver alloy, a magnesium-indium alloy, or an aluminum-magnesium alloy.

(29) 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 [4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-diphenylamine (Compound 11)

(30) 2-Bromo-9,9-dimethyl-7,10-diphenylacridan (2.54 g), 4-(diphenylamino)phenylboronic acid (1.75 g), toluene (25 ml), ethanol (2 ml), and a 2M potassium carbonate aqueous solution (9 ml) were added to a reaction vessel in a nitrogen atmosphere and aerated with nitrogen gas for 30 min under ultrasonic irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.20 g) and stirred at 68° C. for 8 hours. The mixture was allowed to cool to a room temperature, and an organic layer was collected by a liquid separating operation. The organic layer was dried with magnesium sulfate and concentrated under reduced pressure to obtain a yellow amorphous crude product. The crude product was recrystallized with n-hexane, dissolved by adding toluene (30 ml), and purified by adsorption using silica gel (1.17 g Methanol (20 ml) was added to this solution to precipitate crystals, and the crystals were further purified by recrystallization using toluene/methanol to obtain a white powder of [4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-diphenylamine (1.9 g; yield 54%).

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

(32) 1H-NMR (THF-d.sub.8) detected 36 hydrogen signals, as follows. δ (ppm)=7.75 (2H), 7.68 (2H), 7.56-7.54 (3H), 7.47 (2H), 7.40 (2H), 7.35 (2H), 7.24-7.18 (7H), 7.09-7.07 (6H), 6.97 (2H), 6.33-6.30 (2H), 1.80 (6H).

EXAMPLE 2

Synthesis of {4-[10-(9,9-dimethyl-9H-fluorene-2-yl)-9,9-dimethylacridan-2-yl]phenyl}-diphenylamine (Compound 19)

(33) [4-(9,9-Dimethylacridan-2-yl)phenyl]-diphenylamine (2.02 g), 2-bromo-9,9-dimethyl-9H-fluorene (1.37 g), a copper powder (0.036 g), potassium carbonate (0.94 g), sodium bisulfite (0.078 g), and dodecane (4 ml) were added to a nitrogen-substituted reaction vessel and stirred at 200° C. for 35 hours. The mixture was allowed to cool to a room temperature, and toluene (30 ml) and methanol (30 ml) were added. Precipitated insoluble matter was removed by filtration and concentrated under reduced pressure to obtain a black crude product. The crude product was purified by column chromatography (carrier: silica gel; eluent: hexane/toluene), crystallized with diisopropyl ether/methanol, and then crystallized with ethyl acetate/diisopropyl ether/hexane to obtain a pale yellowish white powder of {4-[10-(9,9-dimethyl-9H-fluorene-2-yl)-9,9-dimethylacridan-2-yl]phenyl}-diphenylamine (0.96 g; yield 33%).

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

(35) 1H-NMR (THF-d.sub.8) detected 40 hydrogen signals, as follows. δ(ppm)=8.04 (1H), 7.85 (1H), 7.72 (1H), 7.52-7.46 (5H), 7.36-7.30 (3H), 7.23-7.21 (4H), 7.17 (1H), 7.08-7.07 (6H), 6.97 (2H), 6.90-6.87 (2H), 6.38 (1H), 6.34 (1H), 1.73 (6H), 1.53 (6H).

EXAMPLE 3

Synthesis of [4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-(9,9-dimethyl-9H-fluorene-2-yl)-phenylamine (Compound 27)

(36) 9,9-Dimethyl-2,10-diphenyl-7-(4,4,5,5-tetramethyl-[1,3,2]dioxaboran-2-yl)acridan (2.02 g), (4-bromophenyl)-(9,9-dimethyl-9H-fluorene-2-yl)-phenylamine (1.90 g), toluene (20 ml), ethanol (2 ml), and a 2M potassium carbonate aqueous solution (6 ml) were added to a nitrogen-substituted reaction vessel and aerated with nitrogen gas for 30 min under ultrasonic irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.14 g) and stirred at 72° C. for 8.5 hours. The mixture was allowed to cool to a room temperature, and an organic layer was collected by a liquid separating operation. The organic layer was dried with magnesium sulfate and concentrated under reduced pressure to obtain a brown crude product. The crude product was purified by column chromatography (carrier: silica gel; eluent: hexane/toluene) and crystallized with acetone/methanol to obtain a white powder of [4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-(9,9-dimethyl-9H-fluorene-2-yl)-phenylamine (1.98 g; yield 64%).

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

(38) 1H-NMR (THF-d.sub.8) detected 44 hydrogen signals, as follows. δ(ppm)=7.76 (2H), 7.68-7.62 (4H), 7.56-7.55 (3H), 7.49 (2H), 7.41-7.35 (5H), 7.29-7.20 (8H), 7.13-7.12 (4H), 7.03 (1H), 6.98 (1H), 6.31 (2H), 1.80 (6H), 1.40 (6H).

EXAMPLE 4

Synthesis of (biphenyl-4-yl)-[4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-phenylamine (Compound 12)

(39) 2-Bromo-9,9-dimethyl-7,10-diphenylacridan (3.2 g), (biphenyl-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaboran-2-yl)phenyl]-phenylamine (3.6 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 irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.26 g) and stirred at 72° C. for 7 hours. The mixture was allowed to cool to a room temperature, and methanol (50 ml) was added. A precipitated solid was collected by filtration and washed with water to obtain a red brown crude product. The crude product was dissolved by adding toluene (100 ml) and subjected to adsorptive purification twice using silica gel (3.7 g). The product was then crystallized with toluene/methanol to obtain a white powder of (biphenyl-4-yl)-[4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]-phenylamine (3.42 g; yield 68%).

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

(41) 1H-NMR (THF-d.sub.8) detected 40 hydrogen signals, as follows. δ(ppm)=7.77-7.75 (2H), 7.70-7.67 (2H), 7.59-7.50 (9H), 7.41-7.38 (6H), 7.25-7.21 (6H), 7.15-7.13 (6H), 7.00 (1H), 6.33-6.31 (2H), 2.48 (6H).

EXAMPLE 5

Synthesis of bis(biphenyl-4-yl)-[4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]amine (Compound 13)

(42) 2-Bromo-9,9-dimethyl-7,10-diphenylacridan (2.9 g), bis(biphenyl-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaboran-2-yl)phenyl]amine (4.0 g), toluene (44 ml), ethanol (11 ml), and a 2M potassium carbonate aqueous solution (8.4 ml) were added to a nitrogen-substituted reaction vessel and aerated with nitrogen gas for 30 min under ultrasonic irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.23 g) and stirred at 72° C. for 4.5 hours. The mixture was allowed to cool to a room temperature, and an organic layer was collected by a liquid separating operation. The organic layer was dried with magnesium sulfate and concentrated under reduced pressure to obtain a red crude product. The crude product was dissolved by adding toluene (75 ml), purified by adsorption using silica gel (5.2 g), and purified by recrystallization using toluene/methanol to obtain a whitish powder of bis(biphenyl-4-yl)-[4-(9,9-dimethyl-7,10-diphenylacridan-2-yl)phenyl]amine (3.19 g; yield 64%).

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

(44) 1H-NMR (THF-d.sub.8) detected 44 hydrogen signals, as follows. δ(ppm)=7.77 (2H), 7.69-7.67 (15H), 7.61-7.53 (8H), 7.41-7.18 (11H), 6.33-6.31 (2H), 2.48 (6H).

EXAMPLE 6

Synthesis of (phenyl-4-yl)-[4-{10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan-2-yl}phenyl]-phenylamine (Compound 24)

(45) 2-Bromo-10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan (2.7 g), (biphenyl-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaboran-2-yl)phenyl]-phenylamine (2.8 g), toluene (40 ml), ethanol (10 ml), and a 2M potassium carbonate aqueous solution (8 ml) were added to a nitrogen-substituted reaction vessel and aerated with nitrogen gas for 30 min under ultrasonic irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.13 g) and stirred at 72° C. for 3.5 hours. The mixture was allowed to cool to a room temperature, and methanol (50 ml) was added. A precipitated solid was collected by filtration and washed with water to obtain an orange crude product. The crude product was dissolved by adding toluene (200 ml) and purified by adsorption using silica gel (2.4 g). The product was then crystallized with toluene/methanol to obtain a white powder of (phenyl-4-yl)-[4-{10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan-2-yl}phenyl]-phenylamine (3.07 g; yield 78%).

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

(47) 1H-NMR (THF-d.sub.8) detected 44 hydrogen signals, as follows. δ(ppm)=7.98 (2H), 7.78-7.77 (4H), 7.60-7.39 (12H), 7.37-7.35 (5H), 7.27-7.22 (6H), 7.16-7.13 (6H), 7.01 (1H), 6.42 (2H), 1.82 (6H).

EXAMPLE 7

Synthesis of bis(biphenyl-4-yl)-[4-{10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan-2-yl}phenyl]amine (Compound 23)

(48) 2-Bromo-10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan (2.5 g), bis(biphenyl-4-yl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaboran-2-yl)phenyl]amine (3.0 g), toluene (37 ml), ethanol (9.3 ml), and a 2M potassium carbonate aqueous solution (7.2 ml) were added to a nitrogen-substituted reaction vessel and aerated with nitrogen gas for 30 min under ultrasonic irradiation. The mixture was heated after adding tetrakis(triphenylphosphine)palladium (0.11 g) and stirred at 72° C. for 8.5 hours. The mixture was allowed to cool to a room temperature, and methanol (40 ml) was added. A precipitated solid was collected by filtration and washed with water to obtain an orange crude product. The crude product was dissolved by adding toluene (360 ml), purified by adsorption using silica gel (3.6 g), and crystallized with toluene/methanol three times. Further, methanol (60 ml) was added to the product, and the product was washed and purified by heating under reflux to obtain a white powder of bis(biphenyl-4-yl)-[4-{10-(biphenyl-4-yl)-9,9-dimethyl-7-phenylacridan-2-yl}phenyl]amine (3.04 g; yield 75%).

(49) The structure of the resulting white powder was identified by NMR. The 1H-NMR Measurement result is presented in FIG. 7.

(50) 1H-NMR (THF-d.sub.8) detected 48 hydrogen signals, as follows. δ(ppm)=7.99 (2H), 7.79-7.77 (4H), 7.60-7.48 (16H), 7.40-7.35 (7H), 7.28-7.19 (11H), 6.42 (2H), 1.82 (6H).

EXAMPLE 8

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

(52) TABLE-US-00001 Glass Melting transition point point Compound of Example 1 of the 248° C. 106° C. present invention Compound of Example 2 of the 142° C. 115° C. present invention Compound of Example 3 of the 162° C. 129° C. present invention Compound of Example 4 of the 254° C. 118° C. present invention Compound of Example 5 of the 258° C. 136° C. present invention Compound of Example 6 of the 164° C. 130° C. present invention

(53) 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 9

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

(55) TABLE-US-00002 Work function Compound of Example 1 of the present 5.45 eV invention Compound of Example 2 of the present 5.41 eV invention Compound of Example 3 of the present 5.45 eV invention Compound of Example 4 of the present 5.41 eV invention Compound of Example 5 of the present 5.41 eV invention Compound of Example 6 of the present 5.49 eV invention

(56) 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 10

(57) An organic EL device, as illustrated in FIG. 8, was fabricated by forming a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and a cathode (an aluminum electrode) 8 in this order by vapor deposition on a glass substrate 1 that had been provided beforehand with an ITO electrode as a transparent anode 2.

(58) Specifically, the glass substrate 1 with ITO formed with a film thickness of 150 nm 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 the formation of the hole injection layer 3 by forming Compound 77 of the structural formula below over the transparent anode 2 in a film thickness of 20 nm. The hole transport layer 4 was then formed on the hole injection layer 3 by forming the compound of Example 2 of the present invention (Compound 19) in a film thickness of 40 nm. Thereafter, the light emitting layer 5 was formed on the hole transport layer 4 by forming Compounds 78 and 79 of the structural formulae below in a film thickness of 30 nm using dual vapor deposition at a deposition rate ratio of Compound 78:Compound 79=5:95. Then, the electron transport layer 6 was formed on the light emitting layer 5 by forming Alg.sub.3 in a film thickness of 30 nm. The electron injection layer 7 was then formed on the electron transport layer 6 by forming lithium fluoride in a film thickness of 0.5 nm. Finally, the cathode 8 was formed by vapor-depositing aluminum in a film thickness of 150 nm. The characteristics of the organic EL device thus fabricated were measured in the atmosphere at an ordinary temperature.

(59) Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device produced by using the compound of Example 2 of the present invention (Compound 19).

(60) ##STR00034##

EXAMPLE 11

(61) An organic EL device was fabricated under the same conditions used in Example 10, except that the compound of Example 5 of the present invention (Compound 13) was formed in a film thickness of 40 nm as the material of the hole transport layer 4, instead of using the compound of Example 2 of the present invention (Compound 19). The characteristics of the organic EL device thus fabricated were measured in the atmosphere at an ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device.

COMPARATIVE EXAMPLE 1

(62) For comparison, an organic EL device was fabricated under the same conditions used in Example 10, except that Compound 80 of the structural formula below was formed in a film thickness of 40 nm as the material of the hole transport layer 4, instead of using the compound of Example 2 of the present invention (Compound 19). The characteristics of the organic EL device thus fabricated were measured in the atmosphere at an ordinary temperature. Table 1 summarizes the results of the emission characteristics measurements performed by applying a DC voltage to the organic EL device.

(63) ##STR00035##

(64) TABLE-US-00003 TABLE 1 Current Power Luminance efficiency efficiency Voltage [V] [cd/m.sup.2] [cd/A] [lm/W] (@10 mA/cm.sup.2) (@10 mA/cm.sup.2) (@10 mA/cm.sup.2) (@10 mA/cm.sup.2) Ex. 10 Compound 19 4.82 960 9.61 6.26 Ex. 11 Compound 13 4.96 910 9.10 5.76 Com. Ex. 1 Compound 80 5.17 902 9.03 5.49

(65) As shown in Table 1, the driving voltage when applying a current with a current density of 10 mA/cm.sup.2 was 4.82 V for the compound of Example 2 of the present invention (Compound 19) and 4.96 V for the compound of Example 5 of the present invention (Compound 13), both of which were lower than 5.17 V of Compound 80. The power efficiencies of the compound of Example 2 in the present invention (Compound 19) and the compound of Example 5 in the present invention (Compound 13) were 6.26 lm/W and 5.76 lm/W respectively, which showed improvement over the power efficiency 5.49 lm/W of Compound 80. Further, the compounds of the present invention were improved in both of the luminance and the luminous efficiency compared to Compound 80.

(66) As the above results clearly demonstrate, the organic EL devices using the compounds having an acridan ring structure in the present invention has achieved improvements in luminous efficiency and power efficiency, and a lower actual driving voltage compared to the organic EL device using the Compound 80.

INDUSTRIAL APPLICABILITY

(67) The compounds having an acridan ring structure of the present invention have high hole transportability, excel in amorphousness, and have a stable thin-film state. The compounds are therefore excellent as the compounds for organic EL devices. The organic EL devices fabricated with the compounds 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 electric appliances and illuminations.

DESCRIPTION OF REFERENCE NUMERAL

(68) 1 Glass substrate 2 Transparent electrode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode