CN100528831C - Organic electroluminescent device and phenylenediamine derivative - Google Patents

Abstract

The present invention provides a long-life organic EL device that can reduce the driving voltage of the organic EL device, and provides a material that has low ionization potential and exhibits high hole mobility when used as a layer or region. The organic electroluminescent device includes a pair of electrodes and an organic light-emitting layer sandwiched between the electrodes. It is characterized in that a hole migration region is provided between the electrodes, and it contains a phenylenediamine derivative represented by a specific structural formula. The phenylenediamine derivative exhibits a hole mobility of 10 ^-4 cm ² /V·s or higher when used as a layer or region, and the organic light-emitting layer contains a charge injection auxiliary material.

Description

Organic Electroluminescent Devices and Phenylenediamine Derivatives

This application is a divisional application of the invention patent application No. PCT/JP99/04794 filed on September 3, 1999, entitled "Organic Electroluminescent Devices and Phenylenediamine Derivatives". The original Chinese patent application number is 99801522.9 .

technical field

The present invention relates to an organic electroluminescent device (hereinafter referred to as an organic EL device) and a phenylenediamine derivative, and more specifically, to an organic EL device comprising a pair of electrodes and an organic light-emitting device sandwiched between the pair of electrodes. layer, and a phenylenediamine derivative used as a material for the organic EL device or the like.

Background technique

Organic EL devices are being intensively studied because they are all solid-state devices and can be made into light-weight, thin and low-voltage-driven displays and lighting devices.

When organic EL devices are applied to displays, one problem to be solved is how to make the driving voltage lower. For example, by using an aromatic amine dendrimer disclosed in JP-A-4-308688 as a hole injection material, the driving voltage can be reduced. This compound has a low ionization potential of 5.2 eV due to having a phenylenediamine skeleton, and exhibits an effect of lowering a driving voltage.

However, the hole mobility of the compound having a phenylenediamine skeleton is as small as 3×10 ^-5 cm ² /V·s, so the driving voltage does not drop enough in the high current injection region.

The high-molecular-weight aromatic amine compound disclosed in JP-A-9-301934 has a low ionization potential of 5.2 eV, but has a problem of insufficient hole mobility. It is estimated that the decrease in hole mobility is due to the incorporation of impurities.

That is, in the fluorescence spectrum of the compound disclosed in JP-A-9-301934 (FIG. 1), a luminescent component having a maximum fluorescence wavelength peak at 500 nm or higher is observed, which does not exist originally. This indicates that impurities have been mixed in. Moreover, the voltage increased by 2.7V after only driving for 76 hours, which constituted an obstacle to lowering the driving voltage. From this, it can be seen that in the device disclosed in this publication, the decrease in hole mobility and the increase in driving voltage are due to impurities.

Furthermore, since this compound contains a green fluorescent component, when it is used in the hole transfer region of a blue light emitting device, blue light emission cannot be obtained due to the incorporation of the green light emitting component.

International Patent Publication WO 98/30071 (published on 1998-07-09) discloses an organic electroluminescent device using a compound similar to the present invention, but fails to disclose such an effect, that is, relying on the combined use of a Particularly low voltages can be achieved with light-emitting layers containing charge injection assisting materials.

invention disclosure

An object of the present invention is to provide a long-life organic EL device capable of reducing the driving voltage of the organic EL device.

Another object of the present invention is to provide a material which has a low ionization potential and exhibits a high hole mobility when used as a layer or region.

The present invention is an organic electroluminescence device, which comprises a pair of electrodes and an organic luminescent layer sandwiched between the electrodes, characterized in that the hole transfer region provided between the electrodes comprises the formula (I), A phenylenediamine derivative represented by general formula (II) or general formula (II)', which exhibits a hole mobility of at least 10 ^-4 cm ² /V·s when used as a layer or region , and the organic light-emitting layer includes a charge injection auxiliary material.

General formula (I)

Ar ¹ to Ar ⁶ represent aryl groups with 6 to 24 ring carbon atoms, which may be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring Aryl group or styryl group of carbon atoms substituted. X represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms , diphenylmethylene, ether bond, thioether bond, substituted or unsubstituted vinyl bond or aromatic heterocycle. R ¹ and R ² represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, which can be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring .

General formula (II)

Ar ⁷ to Ar ¹² represent aryl groups with 6 to 24 ring carbon atoms, which can be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms substituted with an aryl group or a styryl group. Y represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond, an aromatic hetero rings or substituted or unsubstituted vinyl bonds. R ³ and R ⁴ represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, and they may be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring.

General formula (II)'

Ar ⁷ to Ar ¹² represent aryl groups with 6 to 24 ring carbon atoms, which can be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms substituted with an aryl group or a styryl group. Y represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond, or an aromatic Heterocycles or substituted or unsubstituted vinyl linkages. R ⁵ and R ⁶ represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, and they may be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring.

The term "hole transport region" as used herein refers to a region of an organic EL device which has a function of transporting holes from an anode. The so-called function of transporting holes means that its hole mobility is 10 ^{-4 cm 2} /V·s or higher under an electric field of 10 ^{4 -10 6 V} /cm. Specific examples of the hole transport region include a hole injection layer, a hole transport layer, etc., and a light emitting layer may also be included in some cases.

In the present invention, the compounds represented by the general formulas (I), (II) and (II)' have a phenylenediamine skeleton and have a low ionization potential, and the central skeleton represented by X and Y can ensure excellent hole mobility. In the present invention, since the phenylenediamine derivative suitable for hole injection or transfer material exists in the hole transfer region, the driving voltage of the organic EL device can be reduced, and the increase in the driving voltage due to continuous driving can also be reduced. can be suppressed.

Furthermore, in the present invention, a light-emitting layer containing a charge injection assisting material must also be used.

The term "charge injection auxiliary material" as used herein refers to a compound whose ionization energy is smaller than that of the main material constituting the light-emitting layer, preferably a compound that assists holes by being added to the light-emitting layer in an amount of 0.1 to 20 wt%. Injected material. With the addition of charge injection auxiliary materials, the organic EL device of the present invention can reduce the driving voltage and also stabilize the driving voltage. The use of phenylenediamine and the incorporation of charge-injection auxiliary materials in the emitting layer leads to an effect which has never been obtained.

As the charge injection assisting material, compounds such as styrylamine derivatives, distyrylarylene derivatives, tristyrylarylene derivatives, diamine derivatives, etc. are used, and those with ionization energy Compounds at 5.0-5.6eV. The charge injection assisting material may emit light correspondingly due to the recombination of holes and electrons occurring in the light emitting layer, or may exhibit the effect of assisting charge injection and not emit light.

The hole transport region preferably has a hole injection layer containing a phenylenediamine derivative represented by the general formula (I), the general formula (II) or the general formula (II)'.

Alternatively, the hole transport region may have a hole transport layer containing a phenylenediamine derivative represented by the general formula (I), the general formula (II) or the general formula (II)'.

In the above, at least one of Ar ¹ to Ar ⁶ in the general formula (I) is preferably a condensed aromatic ring having 10 to 24 ring carbon atoms. By following this, low-voltage driving can be realized, and the lifetime of the device can also be extended.

On the other hand, the compound of the present invention is a phenylenediamine derivative represented by the general formula (III).

General formula (III)

Ar ¹³ to Ar ¹⁸ represent aryl groups with 6 to 24 ring carbon atoms, which can be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms substituted with an aryl group or a styryl group. X represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond, a substituted or Unsubstituted vinyl bond or aromatic heterocycle. R ⁷ and R ⁸ represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, and they can be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring, The condition is: at least one of Ar ¹³ to Ar ¹⁶ and X represents an aryl group containing a styryl group, or one of Ar ¹⁵ , Ar ¹⁸ and the basic skeleton represented by the following chemical formula contains a fused aromatic ring, Aromatic heterocycles or substituted or unsubstituted vinyl groups.

Furthermore, the compound of the present invention is a phenylenediamine derivative represented by the general formula (IV).

General formula (IV)

Ar ¹⁹ to Ar ²⁴ represent aryl groups with 6 to 24 ring carbon atoms, which can be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms substituted with an aryl group or a styryl group. Y represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond, an aromatic hetero rings or substituted or unsubstituted vinyl bonds. R ⁹ and R ¹⁰ represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, and they may be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring.

Alternatively, the compound of the present invention is a phenylenediamine derivative represented by the general formula (V).

General formula (V)

Ar ²⁵ ~ Ar ³⁰ represent aryl groups with 6 to 24 ring carbon atoms, which can be hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms substituted with an aryl group or a styryl group. Y represents a linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond, an aromatic hetero rings or substituted or unsubstituted vinyl bonds. R ¹¹ and R ¹² represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, and they may be bonded to each other to form a substituted or unsubstituted saturated 5-membered ring or saturated 6-membered ring.

Brief description of the drawings

Fig. 1 is a schematic diagram of the fluorescence spectrum of the phenylenediamine derivative STBA-1 of the present invention.

Invention Best Practices

Next, embodiments of the present invention will be described.

(Organic EL device)

(A) phenylenediamine derivatives

The phenylenediamine derivatives used in the organic EL device of the present invention are compounds represented by the general formulas (I), (II) and (II)'.

In general formulas (I), (II) and (II)', examples of aryl groups having 6 to 24 ring carbon atoms include phenyl, biphenyl, naphthyl, anthracenyl group, terphenyl group, pyrenyl group and other groups. Especially preferred are phenyl groups and naphthyl groups.

Examples of the alkyl group of 1 to 6 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl and the like.

Examples of alkoxy groups of 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, Oxygen, n-hexyloxy, etc.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and the like. Especially preferred is the 2,2-diphenylethenyl-1-yl group.

X in the general formula (I), Y in the general formula (II) and Y in the general formula (II)' are each a connecting group, which is a single bond, an arylene group of 6 to 24 ring carbon atoms , an alkylene group of 1 to 6 carbon atoms, a diphenylmethylene group, an ether bond, a thioether bond or an aromatic heterocycle.

Examples of the arylene group having 6 to 24 ring carbon atoms include phenylene, biphenylene, naphthylene, anthracenylene, terphenylene, pyrenylene and the like.

Examples of the alkylene group of 1 to 6 carbon atoms include methylene, isopropylidene, cyclopropylene, cyclohexylene, cyclopentylene and the like.

The diphenylmethylene group may be substituted by an alkyl group having 1 to 6 carbon atoms, or an alkoxy group. Examples of the aromatic heterocycle include pyrrole, furan, thiophene, schirole, triazine, oxadiazole, triazole, oxazole, quinoline, quinoxaline, pyrimidine and the like.

In the compound of general formula (I), at least one of Ar ¹ to Ar ⁶ preferably represents a condensed aromatic ring having 10 to 24 ring carbon atoms or a phenyl group substituted by a styryl group. Examples of the condensed aromatic ring include naphthyl, anthracenyl, pyrenyl, phenanthrenyl, etc., and naphthyl is particularly preferred.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and the like. Especially preferred is the 2,2-diphenylethenyl-1-yl group.

Since the compound of the present invention exists in the hole transport region of the device, the hole mobility of the device can reach 10 ^-4 cm ² /V·s or higher under the electric field of 10 ⁴ -10 ⁶ V/cm.

Specific examples of the phenylenediamine derivatives represented by the general formula (I) include the following compounds given by (PD-01) to (PD-59) and (STBA-1). But the present invention is not limited to these.

Specific examples of the phenylenediamine derivatives represented by the general formula (II) include the following compounds given by (PT-01) to (PT-31). But the present invention is not limited to these.

Due to the small ionization potential of the compounds of general formula (I), (II) and (II)', it is easy to mix impurities, such as oxidation during purification, and the hole mobility may be affected by the presence of these impurities in some cases. decline.

That is, in the method of JP-A-9-301934, since impurities are mixed into the high-molecular-weight aromatic amine compound, sufficient hole mobility cannot be obtained due to traps, etc., as observed in the fluorescence spectrum.

On the other hand, as a result of earnest research by the present inventors on the purification method of the compound, it has been found that the pure compound can be obtained by a column purification method (column purification) using a toluene/hexane series solvent as a solvent. According to this purification method, a compound having a higher purity than that obtained by the column purification method using a halogen series solvent disclosed in JP-A-9-301934 is obtained.

Furthermore, a pure phenylenediamine dimer can be obtained by sublimation purification at a high vacuum of 0.01mmHg or lower, and its fluorescence spectrum, as shown in Figure 1, has a peak in the range of 400-480nm wavelength. The present inventors have confirmed that a hole mobility of 10 ^-4 cm ² /V·s or higher can be obtained only by the phenylenediamine dimer of the present invention exhibiting blue or purple fluorescence (peak wavelength: 400 to 480 nm) .

(B) Structure and materials of organic EL devices

In the production of organic EL devices using the compound of the present invention, structures and materials commonly used in the production of organic EL devices can be used.

Suitable device structures and materials are now described below.

(1) Structure of organic EL device

A representative example of the organic EL device structure employed in the present invention is shown below. Of course, the present invention is not limited to these.

(i) Anode/luminescent layer/cathode

(ii) anode/hole injection layer/light-emitting layer/cathode

(iii) anode/luminescent layer/electron injection layer/cathode

(iv) anode/hole injection layer/light emitting layer/electron injection layer/cathode

(v) anode/organic semiconductor layer/light-emitting layer/cathode

(vi) anode/organic semiconductor layer/electron blocking layer/light-emitting layer/cathode

(vii) anode/organic semiconductor layer/light emitting layer/adhesion improving layer/cathode

(viii) Anode/hole injection layer/hole transport layer/light emitting layer/electron injection layer/cathode

Among these structures, structure (viii) is generally preferred.

The compound of the present invention is contained in the hole transport layer among these constituent components. Its content is selected between 30-100 mol%.

(2) Translucent substrate

The organic EL device of the present invention is fabricated on a light-transmitting substrate. The light-transmitting substrate here is a substrate supporting an organic EL device, preferably a flat substrate with a transmittance of 50% or higher for visible light of 400-700 nm.

Specific examples thereof include glass plates, polymer plates, and the like. Examples of glass plates include, inter alia, soda lime glass, barium strontium glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz, and the like. Examples of polymer sheets include polycarbonates, acrylics, polyethylene terephthalate, polyethersulfone, polysulfone, and the like.

(3) anode

As the anode, metals, alloys, conductive compounds, and mixtures thereof having a large work function (4 eV or higher) are preferably used. Specific examples of such electrode materials include metals such as gold, and conductive materials such as CuI, ITO, _SnO2 , ZnO.

The anode can be obtained by forming a thin layer of electrode material by methods such as vapor deposition and sputtering.

When light emitted from the light-emitting layer is taken from the anode, it is preferable that the anode has a transmittance of the emitted light of 10% or higher. The sheet resistance of the anode is preferably several hundred ohms per square (Ω/□) or less. The film thickness of the anode is generally selected between 10 nm to 1 μm, preferably 10 to 200 nm, depending on the material.

(4) Organic light-emitting layer

The light emitting layer of the organic EL device has the following combinations of functions. They are, (i) injection function, that is, the function that holes can be injected from the hole injection layer and electrons can be injected from the cathode or electron injection layer under an electric field;

(ii) Migration function, that is, the function of migrating the injected charges (electrons and holes) by means of an electric field force; and

(iii) A light emitting function, that is, a function of providing a field for recombination of electrons and holes to promote light emission.

The injection tendency of holes may be different from the injection tendency of electrons, and there may also be a change in mobility represented by hole and electron mobility, but it is preferable that one of these two kinds of charges can migrate.

The light-emitting materials of organic EL devices are mainly organic compounds, and specific examples are related to the required colors and are given below.

In the case of obtaining light emission in the ultraviolet to purple range, compounds represented by the following general formulas can be cited as examples.

In the general formula, X represents the following compounds.

where n is 2, 3, 4 or 5.

Y represents the following compounds.

The compound represented by these general formulas can be a phenyl group, a phenylene group or a naphthyl group, and one or more groups are substituted on it, such as an alkyl group with 1 to 4 carbon atoms, Alkoxy group, hydroxyl group, sulfonyl group, carbonyl group, amino group, dimethylamino group, diphenylamino group and the like.

They may be bonded to each other to form a saturated 5-membered ring or a saturated 6-membered ring. Those bonded to the para-position of the phenyl, phenylene, or naphthyl group are preferred for forming a flat vapor-deposited film because of excellent adhesive properties.

Specifically, the following compounds are exemplified. Particular preference is given to p-quaterphenyl derivatives and p-pentaphenyl derivatives.

(金属螯合的oxinoid化合物)以及苯乙烯基苯系列化合物。In order to obtain luminescence from blue to green, fluorescent whitening agents can be used, such as benzothiazole series, benzimidazole series, benzoxazole series, etc.,

(metal chelated oxinoid compounds) and styrylbenzene series compounds.

For example, specific compound names such as those disclosed in JP-A-59-194393 can be mentioned. Other useful compounds are described in Synthetic Dye Chemistry, 1971, pp. 628-637 and 640.

例如可使用JP-A-63-295695中所公开的那些。其代表性的例子包括8-羟基喹啉系列的金属配合物，例如三(8-醌基)铝(以下简称为Alq)之类。about

For example, those disclosed in JP-A-63-295695 can be used. Representative examples thereof include metal complexes of 8-hydroxyquinoline series, such as tris(8-quinonyl)aluminum (hereinafter abbreviated as Alq) and the like.

As the styrylbenzene series compounds, for example, those disclosed in European Patent No. 0,319,881 and European Patent No. 0,373,582 can be used.

Distyrylpyrazine derivatives disclosed in JP-A-2-252793 can be used as the material of the light emitting layer.

As for other examples, such as polyphenylene series compounds disclosed in European Patent No. 0,387,715, they can also be used as the material of the light-emitting layer.

In addition to these fluorescent whitening agents, metal chelated oxinoid compounds, styrylbenzene series compounds and the like can also be used as the material of the light-emitting layer, for example, 12-phthalopyridone ("Journal of Applied Physics" (J. Appl. Phys.) Volume 27, L713 (1988)), 1,4-diphenyl-1,3-butadiene and 1,1,4,4-tetraphenyl-1,3-butadiene ( "Appl. Phys. Lett." Vol. 56, L799 (1990), naphthalimide derivatives (JP-A-2-305886), perylene derivatives (JP-A-2-189890), oxadiazoles Derivatives (JP-A-2-216791 or oxadiazole derivatives disclosed by Hamada et al. in the 38th Joint Lecture on Applied Physics), aldehyde azine derivatives (JP-A-2-220393), pyridine Oxazine derivatives (JP-A-2-220394), cyclopentadiene derivatives (JP-A-2-289675), pyrrolopyrrole derivatives (JP-A-2-296891), styrylamine derivatives ("Appl.Phys.Lett." Volume 5, L799 (1990)), Coumadin series compounds (JP-A-2-191694); high molecular weight compounds, disclosed in International Patent Publication WO90/13148 and "Appl.Phys .Lett., Vol. 158, 18, p. 1982 (1991), and the like.

In the present invention, aromatic dimethyl series compounds (those disclosed in European Patent No. 0,388,768 and JP-A-3-231970) are preferably used as the light-emitting layer material. Specific examples thereof include 4,4'-bis(2,2-di-tert-butylphenylvinyl)biphenyl (hereinafter abbreviated as DTBPBBi), 4,4'-bis(2,2-diphenylvinyl) Biphenyl (hereinafter abbreviated as DPVBi) etc. and its derivatives.

Also, compounds represented by the general formula (Rs-Q) ₂ -Al-OL disclosed in JP-A-5-258862 can be cited. (In this formula, L represents a hydrocarbon of 6 to 24 carbon atoms containing a phenyl moiety, OL represents a phenoxide ligand, Q represents a substituted 8-hydroxyquinoline ligand, and Rs represents the 8-hydroxyquinoline Substituents on the ring, the substituents are selected to prevent the bonding of two or more substituted 8-hydroxyquinoline ligands to the aluminum atom by means of steric hindrance.)

Specific examples thereof include bis(2-methyl-quinoline-8-oxyl)(p-phenyl-phenoxy)aluminum(III) (hereinafter referred to as PC-7), bis(2-methyl-quinoline Phenyl-8-oxy)(1-naphthyloxy)aluminum(III) (hereinafter referred to as PC-17) and the like.

In addition, in order to efficiently obtain mixed emission of blue and green, for example, a doping method according to JP-A-6-9953 can be employed. In this case, the above-mentioned luminescent material can be used as a host, and as a dopant, for example, a strong fluorescent dye from blue to green can be used, such as Coumadin series and similar fluorescent dyes as hosts.

Specifically, examples of hosts include luminescent materials having a distyrylarylene skeleton, particularly preferably DPVBi; examples of dopants include diphenylaminovinylarylene, particularly preferably such as N,N-diphenylamino Vinylbenzene (DPAVB).

The light emitting layer having white light emission capability is not particularly limited, and examples thereof include the following structures.

(i) The energy levels of each layer of the organic electroluminescent "laminated structure" meet certain regulations, and the light emission is realized by tunnel injection (European Patent 0,390,551);

(ii) A device utilizing tunnel implantation similar to (i), such as a white light-emitting device disclosed in (JP-A-3-230584);

(iii) A light-emitting layer having a 2-layer structure disclosed in (JP-A-2-220390 and JP-A-2-216790);

(iv) The light-emitting layer is divided into a plurality of parts, each of which is composed of a material of a different light-emitting wavelength (JP-A-4-51491);

(v) A blue-emitting substance (fluorescence peak: 380-480nm) is piled up with a green-emitting substance (480-580nm), and a red fluorescent substance is added (JP-A-6-207170);

(vi) The layer emitting blue light contains a blue fluorescent dye, and the layer emitting green light contains a red fluorescent dye and a green fluorescent substance (JP-A-7-142169).

Among the above cases, structure (v) is preferably employed.

Examples of red fluorescent substances are as follows.

As for the method of forming the light emitting layer using the materials described above, known methods such as vapor deposition method, spin coating method, LB method and the like can be used.

It is especially preferable that the light-emitting layer is a molecular deposition film. The molecular stacked film mentioned here refers to a thin layer film formed by deposition of a gaseous material compound, and a film formed by solidification of a solution or a liquid material compound, and the molecular stacked film may be formed according to the LB method. (Molecular stacked membranes) are significantly different, the difference lies in the aggregation structure and high-dimensional structure and the functions derived from them.

Also, as disclosed in JP-A-57-51781, the light-emitting layer can be formed by dissolving a binder such as a resin and the material compound in a solvent to form a solution, and then forming a solution by spin coating or the like. method to form it into a thin film.

There is no special limitation on the film thickness of the light-emitting layer formed in this way, and it can be selected according to specific circumstances. Generally, the film thickness is preferably in the range of 5 nm to 5 μm. The light-emitting layer may consist of a single layer containing one or two or more materials, or may be formed by accumulating with a light-emitting layer containing a compound other than the light-emitting layer described above.

(5) Hole injection layer and hole transport layer

The hole injection and transport layer is a layer that helps inject holes into the light-emitting layer and migrate them to the light-emitting region, and has high hole mobility and low ionization energy, for example, generally at a level of 5.5 eV or lower. As the hole injection and transport layer, it is preferred to use a material capable of transporting holes into the light-emitting layer under low electric field strength, ^and its hole mobility is ^preferably at least It is 10 ^-4 cm ² /V·s.

As the hole injecting and transporting material, phenylenediamine derivatives represented by general formula (I) or general formula (II) are preferably used. At this time, the hole injection and transport layer may be formed using all the compounds of the present invention, or these materials may be mixed with other materials.

There are no special restrictions on the materials used to be mixed with the compound of the present invention to form the hole injection and transport layer, as long as they have the above-mentioned preferred properties, and can be any material selected from conventional materials used as holes in photoconductive materials. Charge transport materials are used, and known materials are used in hole injection layers of electroluminescent devices.

Specific examples thereof include triazole derivatives (see U.S. Patent No. 3,112,197), oxadiazole derivatives (see U.S. Patent No. 3,189,447), imidazole derivatives (see JP-B-37-16096), polyaryl alkane derivatives (see US Patents 3,615,402, 3,820,989, 3,542,544, JP-B-45-555, JP-B-51-10983, JP-A-51-93224, JP-A-55-17105, JP-A-56-4148, JP- A-55-108667, JP-A-55-156953 and JP-A-56-36656), pyrazoline derivatives and pyrazolone derivatives (see US Pat. , JP-A-55-88065, JP-A-49-105537, JP-A-55-51086, JP-A-56-80051, JP-A-56-88141, JP-A-57-45545, JP -A-54-112637 and JP-A-55-74546), phenylenediamine derivatives (see US Pat. , JP-A-54-53435, JP-A-54-110536 and JP-A-54-119925), arylamine derivatives (see U.S. Patent Nos. -B-49-35702, JP-B-39-27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437 and West German Patent 1,110,518), amino-substituted chal Ketone derivatives (see US Patent 3,526,501), oxazole derivatives (disclosed in US Patent 3,257.203), styryl anthracene derivatives (see JP-A-56-46234), fluorenone derivatives (see JP-A -54-110837), hydrazone derivatives (see U.S. Patent 3,717,462, JP-A-54-59143, JP-A-55-52063, JP-A-55-52064, JP-A-55-46760, JP-A -55-85495, JP-A-57-11350, JP-A-57-148749 and JP-A-2-311591), stilbene derivatives (see JP-A-61-210363, JP-A-61-228451 , JP-A-61-14642, JP-A-61-72255, JP-A-62-476 46. JP-A-62-36674, JP-A-62-10652, JP-A-62-30255, JP-A-60-93455, JP-A-60-94462, JP-A-60-174749 and JP-A-60-175052), silazane derivatives (US Patent 4,950,950), polysilane series (JP-A-2-204996), aniline series copolymers (JP-A-2-282263); conductive high molecular weight Oligomers (particularly thiophene oligomers), disclosed in JP-A-1-211399, and the like.

Those described above can be used as materials for the hole injection layer, among which porphyrin compounds (disclosed in JP-A-63-2956965), and aromatic tertiary amine compounds and styrylamine compounds (see U.S. Patent 4,127,412, JP-A-53-27033, JP-A-54-58445, JP-A-54-149634, JP-A-54-64299, JP-A-55-79450, JP-A-55-144250, JP-A-56-119132, JP-A-61-295558, JP-A-61-98353 and JP-A-63-295695), among which aromatic tertiary amine compounds are particularly preferably used.

Furthermore, compounds containing two fused aromatic rings in the molecule disclosed in U.S. Patent No. 5,061,569, such as 4,4'-bis(N-(1-naphthyl)-N-phenylamino ) biphenyl (hereinafter referred to as NPD) and 4,4',4"-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine (hereinafter referred to as MTDATA), three of which One type in which aniline units are bonded into a star-bloom is disclosed in JP-A-4-308688.

As the material of the light-emitting layer, besides the aromatic dimethyl compound, inorganic compounds such as p-type Si, p-type SiC and the like can also be used as the material of the hole injection layer (of the light-emitting layer).

The hole injection and transport layer can be formed by making the compound into a thin film by known methods such as vacuum vapor deposition method, spin coating method, casting (blade coating) method and LB method. The film thickness of the hole injection and transport layer is not particularly limited, and is generally between 5 nm and 5 μm. When the compound of the present invention is present in the hole transport region, the hole injection and transport layer may consist of a single layer comprising 1 or 2 or more materials, or may be formed by a compound containing a hole injection material other than that described above. The hole injection and transport layer of the compound of the transport layer are accumulated.

The organic semiconductor layer is a layer that assists injection of holes or electrons into the light emitting layer, and preferably has a conductivity of 10 ⁻¹⁰ S/cm or higher. Examples of materials for the organic semiconductor layer include conductive dendrites such as thiophene-containing oligomers, arylamine-containing oligomers disclosed in JP-A-8-193191, arylamine-containing dendrimers, and the like.

(6) Electron injection layer

The electron injection layer is a layer that assists injection of electrons into the light emitting layer, and has high electron mobility; the adhesion improving layer is a layer that has particularly good adhesion to a cathode in each electron injection layer. As materials for the electron injection layer, there are metal complexes of 8-hydroxyquinoline and its derivatives.

它包含喔星螯合物(一般，为8-羟基喹啉)。Specific examples of metal complexes of 8-hydroxyquinoline and its derivatives include

It contains an oxine chelate (typically, 8-hydroxyquinoline).

For example, Alq for the disclosed light-emitting material can be used as the electron injection layer.

On the other hand, examples of the oxadiazole derivatives include the following electron transport compounds.

In the formula, Ar ³¹ , Ar ³² , Ar ³³ , Ar ³⁵ , Ar ³⁶ and Ar ³⁹ , each representing a substituted or unsubstituted aryl group, may be the same or different from each other. Ar ³⁴ , Ar ³⁷ , and Ar ³⁸ represent substituted or unsubstituted arylene groups, which may be the same or different from each other.

Examples of aryl groups include phenyl groups, biphenyl groups, anthracenyl groups, perylene groups, and pyrenyl groups. Examples of arylene groups include phenylene, naphthylene, biphenylene, anthracenylene groups, perylene groups, pyrenylene groups, and the like. Examples of substituents include alkyl groups of 1 to 10 carbon atoms, alkoxy groups of 1 to 10 carbon atoms, cyano groups and the like. Electron transport compounds are preferably those which can be formed into thin films.

Specific examples of the electron transport compound include the following compounds.

(7) Cathode

As the cathode, those containing metals, alloys, and conductive compounds having a small work function (4 eV or less), and mixtures thereof can be used as electrode substances. Specific examples of electrode substances include sodium, sodium-potassium alloys, magnesium, lithium, magnesium-silver alloys, aluminum/alumina, aluminum-lithium alloys, indium, rare earth metals, and the like.

The cathode can be prepared by forming the electrode material into a thin film by methods such as vapor deposition, sputtering and the like.

In the case of taking light emitted from the light-emitting layer from the cathode, it is preferable that the cathode has a transmittance of emitted light of 10% or more.

The sheet resistance of the cathode is preferably hundreds of ohms per square or lower, and the film thickness is generally between 10 nm and 1 μm, preferably between 50 and 200 nm.

(8) Preparation of organic EL devices

According to the materials and methods described above, an anode, a light-emitting layer, a hole injection layer and an electron injection layer as needed can be formed, and then a cathode can be formed to form an organic EL device. Alternatively, an organic EL device can be fabricated in the reverse order of the above from cathode to anode.

An example of the production process will be described below, which has a structure including a light-transmitting substrate on which an anode/hole injection layer/light-emitting layer/electron injection layer/cathode are sequentially formed.

On a suitable light-transmitting substrate, a thin film containing an anode material with a film thickness of 1 μm or less, preferably 10-200 nm, is formed by methods such as vapor deposition and sputtering, so as to make an anode.

A hole injection layer is then formed on the anode. Although the formation of the hole injection layer can be carried out by various methods such as the vacuum vapor deposition method, spin coating method, casting method, and LB method described above, it is preferably formed by vacuum vapor deposition because it is easy to obtain Uniform film and less prone to pinholes. In the case of forming the hole injection layer by vacuum vapor deposition, the vapor deposition conditions should be changed depending on factors such as the compound used (hole injection layer material), crystal structure and association structure of the target hole injection layer. It is generally preferred that the conditions should be properly selected within the ^following ranges: vapor deposition source temperature, 50-450°C; vacuum degree, ^10-7-10-3 torr; vapor deposition rate, 0.01-50nm/s; substrate temperature , -50～300℃; film thickness, 5nm～5μm.

Forming of the light-emitting layer, when the light-emitting layer is formed on the hole injection layer, the required organic light-emitting material can be formed into It is realized by thin film, preferably by vacuum vapor deposition method, because it is easy to obtain a uniform film and it is not easy to form pinholes. In the case of forming the light-emitting layer by vacuum vapor deposition, the vapor deposition conditions should be changed depending on the compound used, and generally can be selected within the range of conditions similar to those for the hole injection layer.

An electron injection layer is formed on the light emitting layer. Similar to the hole injection layer and the light emitting layer, it is preferably formed by vacuum vapor deposition to ensure a uniform film. The vapor deposition conditions can be selected within the range of conditions similar to those of the hole injection layer and the light emitting layer.

Depending on the case of the layer containing the hole transport region, the compounds of the present invention can be compound-vapour-deposited with other materials when vacuum vapor deposition is used. When spin coating is used, other materials can be added by mixing.

Finally, the cathode is accumulated to obtain an organic EL device.

The cathode consists of metal and can be formed by vapor deposition or sputtering. However, in order to prevent damage to the underlying organic layer during film formation of this layer, vacuum vapor deposition is preferably used.

The organic EL devices described above are preferably produced continuously from the anode to the cathode using one-step evacuation.

In the case of applying a DC voltage to the organic EL device, light emission can be observed when a voltage of 5 to 40 V is applied in which the anode is positive and the cathode is negative. When a voltage is applied in the opposite polarity, no current flows and no light is emitted. In addition, when an AC voltage is applied and the polarity is in a state where the anode is positive and the cathode is negative, uniform light emission can be observed. The waveform of the alternating current can be arbitrary.

(Phenylenediamine Derivatives)

Examples of the substituents that can be added to the aryl groups having 6 to 24 ring carbon atoms in the general formulas (III), (IV) and (V) representing the phenylenediamine dimers of the present invention include 1 Alkyl groups, alkoxy groups, styryl groups and the like with ~6 carbon atoms.

Examples of aryl groups having 6 to 24 ring carbon atoms include phenyl groups, biphenyl groups, naphthyl groups, anthracenyl groups, terphenyl groups, pyrenyl groups, and benzene Nyl groups and naphthyl groups are preferred.

Examples of the alkyl group of 1 to 6 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl and the like.

Examples of alkoxy groups of 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, Oxygen, n-hexyloxy and other groups.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and the like. Especially preferred is the 2,2-diphenylethenyl-1-yl group.

X in the general formula (III), Y in the general formula (IV) and Y in the general formula (V) are each a connecting group, which is a single bond, an arylene group of 6 to 24 ring carbon atoms, An alkylene group of 1 to 6 carbon atoms, a dibenzylidene group, an ether bond, a thioether bond or an aromatic heterocycle or a substituted or unsubstituted vinyl bond.

Examples of the arylene group having 6 to 24 ring carbon atoms include phenylene, biphenylene, naphthylene, anthracenylene, terphenylene, pyrenylene and the like.

Examples of the alkylene group of 1 to 6 carbon atoms include methylene, apropylene, cyclopropylene and the like.

The dibenzylidene group may be substituted by an alkyl or alkoxy group of 1 to 6 carbon atoms.

Examples of aromatic heterocycles include pyrrole, furan, thiophene, silacyclopentadiene, triazine, oxadiazole, triazole, oxazole, quinoline, quinoxaline, pyrimidine, and the like.

At least one of Ar ¹³ to Ar ¹⁸ in the general formula (III) represents an aryl group with 10 to 24 ring carbon atoms, which is substituted by a styryl group, or one of Ar ¹⁵ , Ar ¹⁸ and X It is a fused aromatic ring, aromatic heterocyclic ring or substituted or unsubstituted vinyl group with 10 to 24 ring carbon atoms.

Examples of fused aromatic rings include naphthyl, anthracenyl, pyrenyl, phenanthrenyl, etc., and naphthyl is especially preferred.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and the like. Especially preferred is the 2,2-diphenylethenyl-1-yl group. Examples of aromatic heterocycles include pyrrole, furan, thiophene, silacyclopentadiene, triazine, oxadiazole, triazole, oxazole, quinoline, quinoxaline, pyrimidine, and the like.

Preferred examples of alkyl groups as ^R7 and ^R8 include methylethyl, isopropyl, tert-butyl, etc.; examples of preferred alkoxy groups include methoxy, ethoxy, isopropoxy base, tert-butoxy group, etc.

In case X is a single bond, R ⁷ and R ⁸ are preferably bonded together to form a divalent group comprising substituted or unsubstituted fluorene.

At least one of Ar ¹⁹ to Ar ²⁴ in the general formula (IV) represents an aryl group with 10 to 24 ring carbon atoms, which is substituted by a styryl group, or one of Ar ¹⁹ to Ar ²⁴ and Y is a fused aromatic ring, aromatic heterocyclic ring or substituted or unsubstituted vinyl group having 10 to 24 ring carbon atoms.

Examples of fused aromatic rings include naphthyl, anthracenyl, pyrenyl, phenanthrenyl, etc., and naphthyl is especially preferred.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and the like. Especially preferred is the 2,2-diphenylethenyl-1-yl group.

Examples of aromatic heterocycles include pyrrole, furan, thiophene, silacyclopentadiene, triazine, oxadiazole, triazole, oxazole, quinoline, quinoxaline, pyrimidine, and the like.

Preferred examples of alkyl groups as ^R9 and ^R10 include methylethyl, isopropyl, tert-butyl, etc.; examples of preferred alkoxy groups include methoxy, ethoxy, isopropoxy base, tert-butoxy group, etc.

In case Y is a single bond, R ⁹ and R ¹⁰ are preferably bonded together to form a divalent group comprising substituted or unsubstituted fluorene.

At least one of Ar ²⁵ to Ar ³⁰ in the general formula (V) represents an aryl group with 10 to 24 ring carbon atoms, which is substituted by a styryl group, or one of Ar ²⁵ to Ar ³⁰ and Y It is a fused aromatic ring, an aromatic heterocyclic ring or a substituted or unsubstituted vinyl group with 10 to 24 ring carbon atoms.

Examples of fused aromatic rings include naphthyl, anthracenyl, pyrenyl, phenanthrenyl and the like, with naphthyl being especially preferred.

Examples of styryl groups include 1-phenylethenyl-1-yl, 2-phenylethenyl-1-yl, 2,2-diphenylethenyl-1-yl, 2-phenylethenyl-2 -(Naphthyl-1-yl)ethenyl-1-yl, 2,2-bis(biphenyl-1-yl)ethenyl-1-yl and other groups, preferably 2,2-diphenylethenyl- 1-yl group.

Examples of aromatic heterocycles include pyrrole, furan, thiophene, silacyclopentadiene, triazine, oxadiazole, triazole, oxazole, quinoline, quinoxaline, pyrimidine and the like.

Preferred examples of alkyl groups as R ^{and R} include methylethyl, isopropyl, tert-butyl, etc.; examples of preferred alkoxy groups include methoxy, ethoxy, isopropoxy base, tert-butoxy group, etc.

In case Y is a single bond, R ¹¹ and R ¹² are preferably bonded together to form a divalent group comprising substituted or unsubstituted fluorene.

Specific examples of the phenylenediamine dimer represented by the general formula (III) include compounds represented by the following chemical formulas (PD-01') to (PD-56'). But the present invention is not limited to these.

It has been found that the phenylenediamine derivative represented by the general formula (III) is particularly preferably selected from the derivatives represented by the general formula (I). Compared with the conventionally known ones disclosed in International Patent Publication WO98/30071, they can obtain conventional features that have never been obtained, namely, (1) compounds having aryl groups containing styryl groups exhibits long lifetime and high fluorescence characteristics after electron injection, so it can be used as a light-emitting material; and (2) it is not easily degraded and has a long lifetime when electrons are injected into a compound whose molecule is Ar ¹⁵ , Ar ¹⁸ , and one of the basic skeletons represented by the following chemical formulas contain a condensed aromatic ring, an aromatic heterocyclic ring, or a substituted or unsubstituted vinyl group.

Specific examples of phenylenediamine dimers represented by the general formula (IV) include those represented by the following chemical formulas (PT-01') to (PT-11') and (PT-23') to (PT-31') compound. But the present invention is not limited to these.

It has been found that the phenylenediamine derivatives represented by general formula (IV) and general formula (V) are particularly preferred. It has been found that these compounds are useful as light-emitting materials because of their high fluorescent properties without degradation after electron injection, and also provide long-life hole injection layers and hole transport layers due to resistance to electron injection.

Next, effects of the present invention will be described based on specific examples.

(Example 1)

Synthesis of 4-iodotriphenylamine

125 g of triphenylamine (manufactured by Hiroshima Wako Co.) was dissolved in 5 L of ethanol under heating, 150 g of mercury oxide was added thereto at 60°C, and then 100 g of iodine was gradually added. Subsequently, the reaction was carried out at reflux temperature for 2 h.

After the reaction, the system was filtered while hot, and the residue was washed with acetone. The filtrate was cooled, and the crystals thus precipitated were filtered off.

The crystals were purified using a column packed with silica gel and using toluene as a developing solvent to obtain 52 g of the target substance.

Synthesis of PD-01

10g of 4,4"-diamino-p-terphenyl (manufactured by Lancaster Synthetics), 20g of 1-iodonaphthalene (manufactured by Hiroshima Wako), 20g of potassium carbonate, 1g of copper powder and 100m1 of nitrobenzene were placed in a 300mL three-necked flask and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co.) with toluene as a developing solvent to obtain 8.4 g of 4,4"-bis(1-naphthylamino)-p-terphenyl.

5g of the product, 15g of 4-iodotriphenylamine, 20g of potassium carbonate, 1g of copper powder and 100mL of nitrobenzene were placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 0.8 g of a pale yellow powder.

As a result of FD-MS, peaks of 999 (M+1) and 499 (1/2·M) corresponding to C ₇₄ H ₅₄ N ₄ =998 were obtained, whereby it was determined to be PD-01.

(Example 2)

(Synthesis of PD-02)

10 g of 9,10-diamino-phenylanthracene (manufactured by Wakayama Seika Industry Co., Ltd.), 20 g of 1-iodonaphthalene (manufactured by Hiroshima Wako Co.), 20 g of potassium carbonate, 1 g of copper powder, and 100 ml of nitrobenzene were placed in a 300 mL three-necked flask , and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene as a developing solvent to obtain 7.7 g of 9,10-bis(1-naphthylaminophenyl)anthracene.

5g of the product, 15g of 4-iodotriphenylamine, 20g of potassium carbonate, 1g of copper powder and 100mL of nitrobenzene were placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 0.8 g of a pale yellow powder.

As a result of FD-MS, peaks of 1,099 (M+1) and 549 (1/2·M) corresponding to C ₈₂ H ₅₈ N ₄ = 1,098 were obtained, whereby it was determined to be PD-02.

(Example 3)

(Synthesis of PD-03)

10g of 4,4'-diaminodiphenylmethane (produced by Hiroshima Wako), 20g of 1-iodonaphthalene (produced by Hiroshima Wako), 20g of potassium carbonate, 1g of copper powder and 100ml of nitrobenzene were placed in a 300mL three-necked flask , and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co.) with toluene as a developing solvent to obtain 9.6 g of bis(4-(naphthyl-1-yl)aminophenyl)methane.

5g of the product, 15g of 4-iodotriphenylamine, 20g of potassium carbonate, 1g of copper powder and 100mL of nitrobenzene were placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 1.2 g of a pale yellow powder.

As a result of FD-MS, peaks of 937 (M+1) and 468 (1/2·M) corresponding to C ₆₉ H ₅₂ N ₄ =936 were obtained, whereby it was determined to be PD-03.

(Example 4)

(Synthesis of PD-04)

10g4,4'-diaminodiphenyl ether (produced by Hiroshima Wako), 20g1-iodonaphthalene (produced by Hiroshima Wako), 20g of potassium carbonate, 1g of copper powder and 100ml of nitrobenzene were placed in a 300mL three-necked flask , and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co.) with toluene as a developing solvent to obtain 9.2 g of bis(4-(naphthyl-1-yl)aminophenyl)ether.

5g of the product, 15g of 4-iodotriphenylamine, 20g of potassium carbonate, 1g of copper powder and 100mL of nitrobenzene were placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 1.0 g of a pale yellow powder.

As a result of FD-MS, peaks of 939 (M+1) and 469 (1/2·M) corresponding to C ₆₈ H ₅₀ N ₄ =938 were obtained, whereby it was determined to be PD-04.

(Example 5)

(Synthesis of N-(1-naphthyl)-4-iododiphenylamine)

10g N-phenyl-N-(1-naphthyl)amine (produced by Hiroshima Wako), 20g p-fluoronitrobenzene (produced by Hiroshima Wako), 20g potassium carbonate, 1g copper powder and 100ml nitrobenzene It was placed in a 300mL three-necked flask and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co.) with toluene as a developing solvent to obtain 9.0 g of N-naphthyl-4-nitrodiphenylamine.

The product was put into an autoclave, 100 mL of DMF (dimethylformamide) and 5 g of 5% Pd/C (palladium on carbon) were added thereto, and hydrogen gas was introduced to 5 kg/cm ² (pressure), followed by stirring. After the catalyst was filtered off, 300 mL of a saturated common salt solution was added thereto, and crystals thus precipitated were filtered off. The crystals were recrystallized from toluene, whereby 6.4 g of N-naphthyl-4-aminodiphenylamine were obtained.

20mL of concentrated sulfuric acid was cooled to 15°C, and 3g of sodium nitrite was added thereto to dissolve it at a temperature of 30°C or lower, and then 100mL of acetic acid was added. 5.0 g of N-naphthyl-4-aminodiphenylamine was added thereto under ice cooling, followed by stirring at room temperature for 1 h. Separately, 10 g of sodium iodide was dissolved in 70° C. water, and the above-mentioned reaction product was added thereto. After stirring at 70° C. for 30 min, it was added to 1 L of water, and then the insoluble matter was filtered off. The insoluble matter was purified by using a column equipped with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene as a developing solvent to obtain 2.7 g of N-(1-naphthyl)-4-iododiphenylamine.

(Synthesis of PD-05)

9,10-bis(1-naphthylaminophenyl)anthracene, 2g N-(1-naphthyl)-4-iododiphenylamine, 5g potassium carbonate, 1g copper powder and 100mL nitrous oxide synthesized in 1g example 2 Benzene was placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 0.3 g of a pale yellow powder.

As a result of FD-MS, peaks of 1,199 (M+1) and 599 (1/2·M) were obtained, corresponding to C ₉₀ H ₆₂ N ₄ =1,198, whereby it was determined to be PD-05.

(Example 6)

(Synthesis of 4-iodo-3'-methyltriphenylamine)

Obtain 3.4g 4-iodo-3'-methyltriphenylamine by the same procedure as Example 5, the difference is that (3-methyl)diphenylamine (manufactured by Hiroshima Wako) is used instead of N-phenyl (1- naphthyl)amine.

(Synthesis of STBA-1)

1g N, N'-diphenyl-4,4'-benzidine (produced by Tokyo Chemical Industry Co., Ltd.), 3g 4-iodo-3'-methyltriphenylamine, 5g potassium carbonate, 1g copper powder and 100mL nitrobenzene It was placed in a 300mL three-necked flask and heated at 200°C for 60h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 0.2 g of a pale yellow powder.

As a result of FD-MS, peaks of 823 (M+1) and 411 (1/2·M) were obtained, corresponding to C ₆₀ H ₄₆ N ₄ =822, whereby it was determined to be STBA-1. The fluorescence spectrum of STBA-1 is shown in FIG. 1 .

(Example 7)

(Synthesis of 4-iodo-4'-nitrobiphenyl)

1,500 g of biphenyl (manufactured by Hiroshima Wako), 444 g of orthoperiodic acid (manufactured by Hiroshima Wako), 987 g of iodine, 5.1 g of acetic acid, 147 mL of sulfuric acid, and 975 g of water were placed in a 10 L flask and heated at 70°C for 2 h with stirring.

After the reaction, 1.3 kg of water was added thereto, and crystals thus precipitated were filtered off. The crystals were recrystallized from 5.5 kg of ethanol to obtain 2,010 g of crystals.

The crystals were dissolved in 14kg of acetic acid, and 1.8L of fuming nitric acid was added dropwise at 80°C, followed by stirring for 8h. After cooling to room temperature, 9.5 kg of methanol was added, and crystals thus precipitated were filtered off and then recrystallized from 27 kg of toluene, thereby obtaining 580 g of 4-iodo-4'-nitrobiphenyl.

(Synthesis of PT-01)

2kg of diphenylamine (manufactured by Hiroshima Wako), 500g of 4-iodo-4'-nitrobiphenyl, 500g of anhydrous potassium carbonate, 20g of copper powder and 2L of nitrobenzene were placed in a 10L flask and heated at 200°C with stirring 15h.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co.) with toluene as a developing solvent to obtain 340 g of crystals.

The crystals were dissolved in 7L of DMF and placed in a 10L autoclave along with 30g of 5% Pd/C. Introduce hydrogen to 25kg/cm ² , raise the temperature to 50°C, and then keep stirring at a pressure of 10-25kg/cm ² for 8 hours. After the catalyst was filtered off, the filtrate was poured into water, the precipitate was filtered off, and then the precipitate was recrystallized from 40 L of toluene, whereby 283 g of crystals were obtained.

250g of crystals, 280g of p-fluoronitrobenzene (manufactured by Hiroshima Wako), 500g of anhydrous potassium carbonate, 10g of copper powder and 1L of nitrobenzene were placed in a 5L flask and heated at 200°C for 32h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene as a developing solvent to obtain 194 g of crystals.

The crystals were dissolved in 4L of DMF and placed in a 10L autoclave along with 30g of 5% Pd/C. Introduce hydrogen to 25kg/cm ² (pressure), raise the temperature to 50°C, and then keep stirring at a pressure of 10-25kg/cm ² for 8 hours. After the catalyst was filtered off, the filtrate was poured into water, and the precipitate was filtered off, which was then recrystallized from 20 L of toluene, thereby obtaining 128 g of crystals.

100g of crystals, 200g of iodobenzene (manufactured by Hiroshima Wako), 250g of anhydrous potassium carbonate, 5g of copper powder and 1L of nitrobenzene were placed in a 5L flask and heated at 200°C for 48h with stirring.

After the reaction, the inorganic matter was filtered off, and the solvent in the mother liquor was distilled off. The residue was purified using a column packed with silica gel (C-200, manufactured by Hiroshima Wako Co., Ltd.) with toluene/hexane=1/2 as a developing solvent. The product was further purified by sublimation under a vacuum of 0.01 mmHg to obtain 23 g of a pale yellow powder.

As a result of FD-MS, peaks of 823 (M+1) and 411 (1/2·M) were obtained, corresponding to C ₆₀ H ₄₆ N ₄ =822, whereby it was determined to be PT-01.

(Example 8)

Organic EL devices were fabricated using PD-1 described above.

A transparent anode of indium tin oxide is formed on glass by coating. The thickness of the ITO is about 750 Angstroms, and the size of the glass is 25 mm x 75 mm x 1.1 mm.

This was placed in a vacuum vapor deposition apparatus (manufactured by ULVAC (Japan)), and the pressure was reduced to about 10 ^-6 torr. A 600 Angstrom thick PD-01 was vapor deposited thereon. Meanwhile, the vapor deposition rate was 2 Å/sec.

A 200 Angstrom thick NPD was then vapor deposited. The vapor deposition rate during this period was 2 angstroms/sec.

DPVTP, as a luminescent material, and DPAVBi, as a carrier injection auxiliary material, were simultaneously vapor-deposited to form a luminescent layer with a thickness of 400 angstroms. The vapor deposition rate of DPVTP is 50 Angstrom/sec; the vapor deposition rate of DPAVBi is 1 Angstrom/sec.

Alq was further vapor deposited at a vapor deposition rate of 2 Angstroms/sec. Finally, aluminum and lithium were simultaneously vapor-deposited to form a 2,000-angstrom-thick cathode. The vapor deposition rate of aluminum was 10 angstroms/sec; the vapor deposition rate of lithium was 0.1 angstroms/sec.

When the fabricated device emitted light at 1,000 nits, the driving voltage was 6.2V. The voltage increase (value) after driving with constant current for 100h is 0.4V; the driving voltage increase value after 1,000h is 0.6V; the half-life is 600h. The ionization energy of DPVTP is 5.9eV; the ionization energy of DPAVBi is 5.5eV.

(Example 9)

An organic EL device was prepared in the same manner as in Example 8, except that PD-02 was used instead of PD-01.

When the manufactured device emits light at 1000 nits, the driving voltage is 6.0V. The voltage increase after driving with constant current for 100h is 0.5V; the driving voltage increase after 1,000h is 0.7V; the half-life is 2,000h.

(Example 10)

An organic EL device was prepared in the same manner as in Example 8, except that PD-03 was used instead of PD-01.

When the manufactured device emits light at 1000 nits, the driving voltage is 6.3V. The voltage increase after driving with constant current for 100h is 0.4V; the driving voltage after 1,000h is 0.6V.

(Example 11)

An organic EL device was prepared in the same manner as in Example 8, except that PD-04 was used instead of PD-01.

When the manufactured device emits light at 1000 nits, the driving voltage is 6.2V. After 100 hours of constant current driving, the voltage increase value is 0.4V; after 1,000 hours, the driving voltage increase value is 0.7V.

(Example 12)

An organic EL device was prepared in the same manner as in Example 8, except that PD-05 was used instead of PD-01.

When the manufactured device emits light at 1000 nits, the driving voltage is 6.1V. The voltage increase after driving with constant current for 100h is 0.5V; the driving voltage increase after 1,000h is 0.6V; the half-life is 2,100h.

(Example 13)

An organic EL device was prepared in the same manner as in Example 8, except that STBA-1 was used instead of PD-01.

When the manufactured device emits light at 1000 nits, the driving voltage is 6.1V. The voltage increase after driving with constant current for 100h is 0.4V; the driving voltage increase after 1,000h is 0.6V; the half-life is 1,200h.

As described above, the compound (III) of the present invention exhibits a particularly low driving voltage, a small voltage rise and a long half-life. This result shows that the compound (III) of the present invention is superior to STBA-1 in the above-mentioned properties.

(Example 14)

A glass substrate with ITO (Indium Tin Oxide) coating (manufactured by Asahi Glass Co., 15 ohms per square, 1,500 angstroms) was cut into 25 mm × 25 mm, and a transparent adhesive tape (width: 12mm), the tape is produced by Scotch Company, and no air bubbles are included after pasting. The substrate is soaked in an etching liquid, thereby forming a pattern.

The etched substrate was placed in a vacuum vapor deposition device (manufactured by ULVAC (Japan)), and then the pressure was reduced to about 10 ⁻⁶ torr. A 500 Angstrom thickness of STBA-1 was vapor deposited thereon. The vapor deposition rate during this period was 2 angstroms/sec.

Alq was then vapor-deposited to a thickness of 500 angstroms at a vapor deposition rate of 2 angstroms/sec.

Finally, magnesium was vapor-deposited simultaneously with silver to form a 2,000-angstrom-thick cathode. The vapor deposition rate of magnesium was 10 angstroms/sec; the vapor deposition rate of silver was 1 angstroms/sec.

In addition, a 1,000 angstrom thick layer of silver was deposited by vapor deposition as an anti-oxidation protective film. The electrode area is 5mm×5mm.

When the manufactured device emits light at 100 nits, the driving voltage is 4.8V.

After 100 hours of constant current driving, the voltage increase value is 0.8V; after 1,000 hours, the driving voltage increase value is 1.3V.

(Example 15)

An organic EL device was prepared in the same manner as in Example 8, except that PT-01 was used instead of PD-01.

When the fabricated device emitted light at 1,000 nits, the driving voltage was 6.2V. The voltage increase value after 100h driving with constant current is 0.3V; the driving voltage increase value after 1,000h is 0.5V.

(Example 16)

An organic EL device was prepared in the same manner as in Example 8. However, STBA-1 was used instead of PD-01, and as a blue light-emitting material, DPA2 represented by the following chemical formula disclosed in International Patent Publication WO98/30071 (published on 1998-07-09) was used instead of DPVTP. DPAVBi was added as a charge injection auxiliary material.

In this example, when the fabricated device emits light at 1,000 nits, the driving voltage is 6.3V. After 100h driving with a constant current, the voltage increase value is 0.4V; after 1,000h, the driving voltage increase value is 0.7V; the half-life is 1,200h.

When the organic EL device in Comparative Example 4 to be described below, in which no charge injection auxiliary material DPAVBi is added, is compared with the organic EL device of this example, due to the organic EL device of the present invention, charges are added to the luminescent material. The auxiliary material is injected, and a compound represented by the general formula (I) is used in the hole transport region, so the organic EL device of the present invention obtains such characteristics that it can be driven at a low voltage and the voltage rises after constant current driving Fewer, and long life.

(Example 17)

This example is an application example as a luminescent material. PD-05' was vapor-deposited to a thickness of 800 angstroms on glass coated with indium tin oxide. Subsequently, aluminum and lithium were simultaneously vapor-deposited to form a cathode comprising an aluminum-lithium alloy with a lithium content of 3 wt%.

When a voltage of 6.0 V was applied to the obtained light emitting device, a luminance of 400 nits was obtained. The half-life is 300h.

(Example 18)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-35'.

When a voltage of 5.5 V was applied to the obtained light emitting device, a luminance of 400 nits was obtained. The half-life is 340h.

(Example 19)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-36'.

When a voltage of 7.0 V was applied to the obtained light emitting device, a luminance of 350 nits was obtained. The half-life is 250h.

(Example 20)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-38'.

When a voltage of 6.2 V was applied to the obtained light emitting device, a luminance of 280 nits was obtained. The half-life is 400h.

(Example 21)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-44'.

When a voltage of 8.0 V was applied to the obtained light emitting device, a luminance of 440 nits was obtained. The half-life is 460h.

(Example 22)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-49'.

When a voltage of 4.7V was applied to the obtained light emitting device, a luminance of 380 nits was obtained. The half-life is 340h.

(Example 23)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PD-54'.

When a voltage of 6.2 V was applied to the obtained light emitting device, a luminance of 250 nits was obtained. The half-life is 280h.

(Example 24)

A light-emitting device was prepared in the same manner as in Example 17, except that PT-01' was used instead of PD-05'.

When a voltage of 5.3 V was applied to the obtained light emitting device, a luminance of 450 nits was obtained. The half-life is 400h.

(Example 25)

A light-emitting device was prepared in the same manner as in Example 17, except that PT-04' was used instead of PD-05'.

When a voltage of 5.6 V was applied to the obtained light emitting device, a luminance of 280 nits was obtained. The half-life is 320h.

(Example 26)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PT-08'.

When a voltage of 4.8 V was applied to the obtained light emitting device, a luminance of 340 nits was obtained. The half-life is 250h.

(Example 27)

A light-emitting device was prepared in the same manner as in Example 17, except that PT-10' was used instead of PD-05'.

When a voltage of 5.7 V was applied to the obtained light emitting device, a luminance of 300 nits was obtained. The half-life is 280h.

(Example 28)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced with PT-25'.

When a voltage of 6.2 V was applied to the obtained light emitting device, a luminance of 320 nits was obtained. The half-life is 360h.

(comparative example 1)

An organic EL device was prepared in the same manner as in Example 8, except that NPDATA was used instead of PD-01.

When the fabricated device emitted light at 1,000 nits, the driving voltage was 8.4V. After 100 hours of constant current driving, the voltage increase value is 0.5V; after 1,000 hours, the driving voltage increase value is 0.7V.

(comparative example 2)

An organic EL device was prepared in the same manner as in Example 8, except that NPD was used instead of PD-01.

When the fabricated device emitted light at 1,000 nits, the driving voltage was 11.8V. After 100 hours of constant current driving, the voltage increase value is 1.4V; after 1,000 hours, the driving voltage increase value is 3.8V.

(comparative example 3)

An organic EL device was prepared in the same manner as in Example 8, except that HI-01 was used instead of PD-01.

When the fabricated device emitted light at 1,000 nits, the driving voltage was 8.1V. The voltage increase after driving with constant current for 100h is 0.5V; the driving voltage after 1,000h is 0.8V.

(comparative example 4)

An organic EL device was fabricated in the same manner as in Example 16, except that the charge injection assisting material DPAVBi was not added.

In this case, when the fabricated device emitted light at 1,000 nits, the driving voltage was 7.0V. After 100 hours of constant current driving, the voltage increase value is 1.2V; after 1,000 hours, the driving voltage increase value is 2.0V. The half-life in this example is 800h.

(comparative example 5)

A light-emitting device was prepared in the same manner as in Example 17, except that PD-05' was replaced by STBA-1.

When a voltage of 9.4 V was applied to the obtained light emitting device, a luminance of 170 nits was obtained. The half-life is 20h.

A comparison between the results obtained from the light-emitting device of Comparative Example 5 and those obtained from the light-emitting devices of Examples 18 to 23 found that, in the case of using STBA-1 as a light-emitting material, it had an extremely short lifetime. This is because the material degrades after electron injection into STBA-1.

However, the compound represented by the general formula (III) of the present invention has a long half-life and is not easily degraded after electron injection.

Therefore, since there is a small amount of electron injection even in the hole transport region, it is preferable to use the electron injection resistant compound represented by the general formula (III) also in the hole transport region.

(comparative example 6)

A light-emitting device was prepared in the same manner as in Example 17, except that PT-01 was used instead of PD-05'.

When a voltage of 8.9 V was applied to the obtained light emitting device, a luminance of 120 nits was obtained. The half-life is 30h.

A comparison between the results obtained from the light-emitting device of Comparative Example 6 and those obtained from the light-emitting devices of Examples 24 to 28 found that, on the one hand, the compound represented by PT-01 did not exhibit resistance to electron injection, and on the other hand, as Compounds represented by general formula (IV) and general formula (V) other than PT-01 exhibit resistance to electron injection. However, the use of PT-01 in the hole transport region, as shown in the previous examples, is no problem since the injection of electrons is small and thus essentially no degradation occurs. Also, when the compounds represented by the general formulas (III), (IV) and (V) which are highly resistant to electron injection are used, the lifetime of the light emitting device itself can be extended.

From the above results, it can be seen that by using the compound of the present invention in the hole transport region, the production of a long-life organic EL device in which the voltage required to exhibit constant light emission is greatly reduced can be realized.

Due to purification to avoid impurities, voltage rise during driving becomes extremely small.

Industrial application

As described above, according to the present invention, a phenylenediamine derivative having a low ionization potential and a large hole mobility can be obtained. When the phenylenediamine derivative exists in the hole transport layer in the organic light-emitting layer between a pair of electrodes, and the organic light-emitting layer of the organic EL device is formed by adding a charge injection auxiliary material, it can be driven. Voltage reduction and extended device life.

Claims (2)

1. A phenylenediamine derivative represented by the general formula (III),

General formula (III) Ar ¹³ to Ar ¹⁸ represent aryl groups with 6 to 24 ring carbon atoms, which are unsubstituted or hydrogen atoms, alkyl or alkoxy groups with 1 to 6 carbon atoms, 6 to 24 ring carbon atoms The aryl group or styryl group of carbon atoms is substituted, and X represents the linking group, which is a single bond, an arylene group with 6 to 24 ring carbon atoms, an alkylene group with 1 to 6 carbon atoms, benzylidene, ether bond, thioether bond, vinyl bond or aromatic heterocycle, R ⁷ and R ⁸ represent an alkyl group, an alkoxy group or a hydrogen atom with 1 to 6 carbon atoms, or they are bonded to each other to form a saturated 5-membered ring or a saturated 6-membered ring, provided that at least one of Ar ¹³ to Ar ¹⁶ and X represents an aryl group containing a styryl group, or Ar ¹⁵ , Ar ¹⁸ and One of the basic backbones represented by the following chemical formulas contains fused aromatic rings, aromatic heterocyclic rings or vinyl groups, 2. An organic electroluminescent device, which comprises a pair of electrodes and an organic light-emitting layer sandwiched between the electrodes, is characterized in that a hole transfer region is provided between the electrodes, and it comprises the formula ( III) Represented phenylenediamine derivatives.

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