KR20090014118A - Compound for use in organic electroluminescent device and composition for use in organic electroluminescent device, and organic electroluminescent device - Google Patents

Abstract

A compound for an organic electroluminescent device is provided to form a thin film conveniently by any one of a wet method and a dry method, to realize hole-transport and electronic transport property and to show excellent light-emitting property. A compound for an organic electroluminescent device comprises a compound indicated as the following chemical formula (I). In the chemical formula (I), Ar^1 and Ar^2 are independently a divalent organic radical containing any one of an aromatic ring, condensed ring and heterocyclic ring within their structure or a single bond; Ar^3 and Ar^4 are independently a monovalent organic radical containing any one of an aromatic ring, condensed ring and heterocyclic ring within their structure, wherein Ar^3 and Ar^4 bonded to the same nitrogen atom and can form a ring structure; and R^1 shows a monovalent organic radical, hydrogen atom or fluorine atom.

Description

COMPOSITION FOR USE IN ORGANIC ELECTROLUMINESCENT DEVICE AND COMPOSITION FOR USE IN ORGANIC ELECTROLUMINESCENT DEVICE, AND ORGANIC ELECTROLUMINESCENT DEVICE}

The present invention relates to an organic electroluminescent device compound, an organic electroluminescent device composition, and an organic electroluminescent device used as a material for an organic electroluminescent device.

The organic electroluminescent element (hereinafter also referred to as "organic EL element") has excellent characteristics such as being able to be driven by DC voltage, being a self-luminous element, having a wide viewing angle, high visibility, and fast response speed. Therefore, it is expected as a next generation display element, and the research is actively performed.

Such organic EL devices include a multilayer having a single layer structure in which a light emitting layer containing an organic material is formed between an anode and a cathode, a structure having a hole transporting layer between an anode and a light emitting layer, and an electron transporting layer between a cathode and a light emitting layer. The structure is known. All of these organic EL elements emit light by recombination of electrons injected from the cathode and holes injected from the anode in the light emitting layer (for example, refer to Patent Document 1 below).

Conventionally, in an organic EL element, it has a multilayer structure which has a hole transport layer between an anode and a light emitting layer, and has an electron transport layer between a cathode and a light emitting layer, and is respectively preferable as a constituent material of a hole transport layer and an electron transport layer, specifically, The low molecular crystalline material having the hole transporting property which is preferable as a constituent material of the hole transporting layer, and the low molecular crystalline material having the electron transporting property which is preferable as the constituent material of the electron transporting layer are used to achieve high efficiency.

Here, as a low molecular crystalline material exhibiting electron transportability, for example, BND (2,5-bis (1-naphthyl) -1,3,4-oxadiazole) may be mentioned (B3LYP-type category in FIG. 11). Showing the shape of LUMO and HOMO of BND calculated by the density functional method using a function).

In the organic EL device, electrons injected from the cathode mainly move along the intermolecular overlap of the lowest unoccupied orbital (LUMO) of the molecules constituting the electron transport layer. LUMO of a material having an electron transport property such as BND is generally a molecule It is known that it is a pi ^* orbit which has spread and delocalized inside, and its energy rank is lowered (electron affinity is increased), thereby increasing the electron injection efficiency and electron transportability. Indeed, the LUMO of BND is lower than that of the molecule about the material having hole transport properties, while the distribution shape of the highest occupied orbital (HOMO) of BND is also typical π orbit, and the range (width) of the distribution is almost the same as that of LUMO. Is in agreement.

On the other hand, as a low molecular crystalline material having hole transporting property, for example, α-NPD ([N, N'-di (naphthalen-1-yl) -N, N'-diphenylbenzidine]) 12 shows the shape of the LUMO and HOMO of α-NPD calculated by the density functional method using the B3LYP type function.

In the organic EL device, holes injected from the anode mainly move along the intermolecular overlap of the HOMO orbits of the molecules constituting the hole transport layer, and the HOMO of the material having hole transporting properties such as α-NPD is generally spread in the molecule and It is known that it is a refined pi orbit, and its energy rank rises (the ionization potential is lowered), thereby increasing the hole injection efficiency and the hole transportability. In fact, the distribution shape of HOMO of α-NPD is a typical? Orbit, and the range (width) of the distribution almost coincides with LUMO.

As described above, since the constituent materials of the hole transport layer and the electron transport layer are required to have opposite properties, respectively, it is difficult to form the hole transport layer and the electron transport layer using the same constituent material. In particular, the reason why it is difficult to form the hole transport layer and the electron transport layer by the same material is that the distribution shape of HOMO and LUMO is the whole molecule in any of materials such as BND which exhibits electron transportability and α-NPD which exhibits hole transportability. Is superimposed largely, and the single electron transition from HOMO to LUMO is an allowable transition having a large oscillator strength. According to the time dependent density functional method (TD-DFT) calculation, the lowest energy single electron excitation of BND is the transition from HOMO to LUMO (wavelength: 370 nm, oscillator intensity: 0.479), and also the lowest energy single electron excitation of α-NPD. Since the transition from HOMO to LUMO (wavelength: 399 nm, oscillator intensity: 0.319) is largely spatially overlapping with HOMO and LUMO in the organic compound, furthermore, when a transition of one electron between them is allowed, The hole is more likely to recombine in its compound or in the energy band formed by the aggregate of the compound, and as a result, it is difficult for the excitation energy of the molecule to be efficiently transferred to the phosphorescent material, which is a constituent material of the light emitting layer of the organic EL device. I think. On the contrary, in the case where the vibration intensity in the single electron transition from HOMO to LUMO is zero (forbidden transition) or very low, the probability of no radiation deactivation increases, so it is considered that it is not preferable as a material for organic EL elements.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-257076

Based on the above circumstances, the present invention has been conducted by the present inventors. As a result, a material has both electron transportability and hole transportability, and (a) both spaces in the distribution shape of HOMO and LUMO. As small as possible, the superposition of (b) a plurality of aromatic rings in the molecule have a twisted structure, not coplanarity, and the separation of HOMO and LUMO is enhanced, (c) monoelectron excitation from HOMO to LUMO is prohibited. And (d) discover molecular design guidelines that require HOMO and LUMO to be at appropriate energy levels, respectively, to ensure balance of electron transport and hole transport and transparency in the visible region, This is achieved by constructing a compound that satisfies the conditions. The objective is to provide the compound for organic electroluminescent elements and the composition for organic electroluminescent elements which have both a hole transporting property and an electron transporting property, and are used suitably as a light emitting material for organic electroluminescent elements.

Another object of the present invention is to provide an organic electroluminescent device having excellent luminescence properties.

Here, in the compound group constructed based on the molecular design guideline, the "frontier molecular orbit" named by Dr. Kenichi Fukui, that is, HOMO and LUMO are almost separated in the distribution shape and the single electron excitation state, and as a result, Since the transition from HOMO to LUMO is a transition of electrons in the molecule, it can be called a "frontier-separated" organic EL compound.

The compound for an organic EL device of the present invention is based on the molecular design guideline of the frontier-separated organic EL compound by the present inventors. While fused in one molecule, it is constructed as a compound that satisfies the conditions of the design guideline (electronic state).

The compound for organic electroluminescent elements of this invention consists of a compound represented by following formula (I).

<Formula (I)>

[Ar ¹ And Ar ² each independently represent a divalent group or a single bond having any one of an aromatic ring, a condensed ring, and a heterocycle in its structure, and Ar ³ and Ar ⁴ each independently represent an aromatic ring, a condensed ring in its structure; And a monovalent group having any one of heterocycles, and Ar ³ and Ar ⁴ bonded to the same nitrogen atom may combine with each other to form a ring structure, and R ¹ is a monovalent organic group, a hydrogen atom or a fluorine atom Indicates

The composition for organic electroluminescent elements of this invention contains 100 mass parts of components containing the said compound for organic electroluminescent elements, 1-20 mass parts of components containing a phosphorescent compound, and 100-100,000 mass parts of organic solvents. It is characterized by.

The organic electroluminescent device of the present invention is characterized by having any one of a hole injection transport layer, an electron injection transport layer and a light emitting layer formed by the compound for an organic electroluminescent device.

The phosphorescent organic electroluminescent device of the present invention is characterized by having a light emitting layer containing the compound for an organic electroluminescent device and a phosphorescent compound.

In the phosphorescent organic electroluminescent element of this invention, it is preferable that a light emitting layer is formed by using the said composition for organic electroluminescent elements.

The compound for organic electroluminescent devices of the present invention is useful as an organic electroluminescent device material because it has good electron transporting properties and hole transporting properties and also has good luminescence properties.

The organic electroluminescent device compound of the present invention is also useful as an organic electroluminescent device material in that a thin film can be easily formed by any of the dry method and the wet method.

According to the composition for organic electroluminescent elements of the present invention, a thin film can be easily formed by a wet method, and as a first constituent component thereof, a phosphorescent compound having phosphorescence property is contained, and as a second constituent component, Since the said compound for organic electroluminescent elements is contained, the organic electroluminescent element which has the outstanding light emission characteristic can be obtained.

According to the organic electroluminescent device of the present invention, by using the compound for an organic electroluminescent device as the constituent material of any one of a hole injection transport layer, an electron injection transport layer and a light emitting layer, good light emission characteristics can be obtained.

Further, according to the phosphorescent organic electroluminescent device of the present invention, by using the compound for an organic electroluminescent device together with the phosphorescent compound as a constituent material of the light emitting layer, it is possible to obtain excellent luminescence properties by phosphorescence.

The phosphorescent organic electroluminescent device can be produced by forming a light emitting layer using the composition for organic electroluminescent devices.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail.

<Compound for Organic EL Device>

The compound for organic electroluminescent element of this invention is represented by the said General formula (I), and is useful as a material for organic electroluminescent element.

In formula (I), Ar ¹ and Ar ² each independently represent a divalent group or a single bond having any one of an aromatic ring, a condensed ring and a heterocycle in its structure, and these Ar ¹ and Ar ² are the same May be different or different.

As a divalent group which shows group Ar <^1> and group Ar <^2> , For example, what contains aromatic rings, such as a phenylene group and a tolylene group, in the structure, For example, contains condensed rings, such as a naphthylene group, in the structure And a heterocyclic ring such as, for example, a thiophene group or a pyridylene group, in the constitution, and specifically, for example, a group represented by the following formulas (i-1) to (i-5) Etc. can be mentioned.

In addition, Ar <^3> and Ar <^4> in general formula (I) respectively independently represent the monovalent group which has any of an aromatic ring, a condensed ring, and a heterocyclic ring in the structure, These Ar <^3> and Ar <^4> may be the same thing. And may be different, but the same is preferred. In addition, Ar ³ and Ar ⁴ bonded to the same nitrogen atom may be bonded to each other to form a ring structure.

As a monovalent group which shows group Ar <^3> and group Ar <^4> , For example, group which contains aromatic rings, such as a phenyl group and a tolyl group, in its structure, For example, group which contains condensed rings, such as a naphthyl group, in its structure, For example, a pyridyl group etc. are mentioned.

In addition, when group Ar <^3> and group Ar <^4> combine with each other and form ring structure, these two groups form a carbazole group etc., for example.

In addition, R <^1> in general formula (I) represents a monovalent organic group, a hydrogen atom, or a fluorine atom.

As the monovalent organic group representing the group R ^1, for example a methyl group, an ethyl group, etc. C 1 -C 20 alkyl group, for example phenyl, tolyl aryl group having 6 to 20 carbon atoms such as a group, e. G. Trifluoroacetic C1-C20 alkyl fluoride groups, such as a methyl group, etc. are mentioned, Among these, a phenyl group is preferable.

As a preferable specific example of the compound for organic electroluminescent elements of this invention, the compound represented by following General formula (I-1)-General formula (I-12) is mentioned.

As an example of the synthesis | combining method of the compound for organic electroluminescent element of this invention as above, the synthesis | combining process of the compound for organic electroluminescent element represented by General formula (I-8) is shown by following Reaction formula (1).

The compound for an organic EL device of the present invention can easily form a film by a dry method such as a vacuum deposition method, and excellent solubility with respect to a solvent can be obtained, thereby easily preparing a coating liquid for forming a thin film. Therefore, a thin film can be formed easily by the said coating liquid. Therefore, the said compound for organic electroluminescent elements is useful as an organic electroluminescent element material also in the point which has high thin film formation ability.

Specifically, the compound for an organic EL device of the present invention has both good electron transporting properties and hole transporting properties due to its structure, and for example, constitutes a hole injection transporting layer and an electron injection transporting layer of the organic EL device. It can be used suitably as a material, and can be used suitably as a material which comprises the light emitting layer of a phosphorescence organic electroluminescent element by combining with the below phosphorescence compound which has phosphorescence as a host compound. Moreover, since the compound for organic electroluminescent element itself has favorable light emission characteristic, it can be used suitably also as a light emitting material which comprises independently the light emitting layer of an organic electroluminescent element.

Thus, when using the compound for organic electroluminescent element of this invention as an organic electroluminescent element material, it can use 1 type or in combination of 2 or more types.

Here, the compound for organic electroluminescent elements of this invention should be as small as possible in spatial distribution of both in (a) distribution shape of HOMO and LUMO, and (b) the some aromatic ring in a molecule is twisted instead of coplanar. Have a structure and enhanced separation of HOMO and LUMO, (c) monoelectron excitation from HOMO to LUMO is not a forbidden but acceptable transition, and (d) in the balance and visible range of electron transport and hole transport In order to ensure transparency, HOMO and LUMO satisfy the molecular design guidelines provided that they are each at an appropriate energy level, and a compound group constructed based on the molecular design guideline shows that HOMO and LUMO correspond to its distribution shape. It is almost separated in the electron-excited state, and as a result, the transition from HOMO to LUMO becomes a transition of electrons moving in the molecule. An organic EL compound ". 8 to 10 show the shapes of LUMO and HOMO calculated by the density functional method using the B3LYP type function with respect to some examples of the compound for an organic EL device of the present invention, which is a frontier-separated organic EL compound.

That is, the compound for an organic EL device of the present invention satisfies the molecular design guideline of the frontier-separated organic EL compound, has a site having excellent electron transportability and a site having excellent hole transportability, and is a compound in which these are fused in one molecule to be.

<Composition for Organic EL Device>

The composition for organic electroluminescent element of this invention is 100 mass parts of components containing the said organic electroluminescent element compound (henceforth "EL element compound component"), and the component containing a phosphorescent compound (henceforth "light emission" Component ”) and 20 to 100 parts by mass of the organic solvent.

As a phosphorescent compound which comprises a light emitting component, an iridium complex compound, a platinum complex compound, a palladium complex compound, a rubidium complex compound, an osmium complex compound, a rhenium complex compound, etc. are mentioned, Among these, an iridium complex compound is especially preferable.

As an iridium complex compound, for example, iridium, 2-phenylpyridine, 3-phenylpyridine, 2-phenylpyrimidine, 4-phenylpyrimidine, 5-phenylpyrimidine, bipyridyl, 1-phenylpyrazole, 2 -Phenylquinoline, 2-phenylbenzothiazole, 2-phenyl-2-oxazoline, 2,4-diphenyl-1,3,4-oxadiazole, 5-phenyl-2- (4-pyridyl)- And complex compounds with nitrogen atom-containing aromatic compounds such as 1,3,4-oxadiazole and derivatives thereof.

As a specific example of such an iridium complex compound, the compound represented by following formula (1)-formula (6) is mentioned, for example.

In the above formulas (1) to (6), R ² to R ⁴ each independently represent a substituent containing a fluorine atom, a trifluoromethyl group, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, It may be the same or different. x is an integer of 0-4, y is an integer of 0-4, z is an integer of 0-3, w is an integer of 0-2.

In the above, the substituents R ² to R ⁴ having 1 to 20 carbon atoms in the alkyl group Examples of the syntax element related to, methyl, ethyl, n- propyl, i- propyl, n- butyl, sec- butyl, t- butyl Group, n-hexyl group, n-octyl group, etc. are mentioned.

Further, specific examples of the aryl group having 6 to 20 carbon atoms of the substituents R ² to R ^4, phenyl, o- tolyl, m- tolyl, p- tolyl, 2,3-xylyl group, 2,4- A xylyl group, 2, 5- xylyl group, 2, 6- xylyl group, 3, 4- xylyl group, 3, 5- xylyl group, 4-biphenyl group, 1-naphthyl group etc. are mentioned. .

In the composition for organic EL devices of the present invention, it is preferable to use an iridium complex compound in which x and y are both 0 in the general formula (1) as the iridium complex compound.

The content rate of the light emitting component in the composition for organic electroluminescent elements of this invention is 1-20 mass parts with respect to 100 mass parts of compound components for EL elements, Preferably it is 1-10 mass parts.

When the ratio of luminescent component is excessive, there exists a possibility that the phenomenon of concentration quenching in which luminescence brightness will reduce rather may arise.

An organic solvent dissolves the compound for organic electroluminescent elements of this invention which comprises the compound component for EL elements, and the phosphorescent compound which comprises a light emitting component, and, thereby, the solution containing an EL element compound component and a light emitting component is prepared. It is for manufacturing.

The organic solvent is not particularly limited as long as it can dissolve the compound for organic EL device and the phosphorescent compound of the present invention, and specific examples thereof include aromatic hydrocarbons such as toluene, xylene and mesitylene; Halogenated hydrocarbons such as chloroform, dichloroethane, tetrachloroethane, chlorobenzene and o-dichlorobenzene; Amides such as N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone, 2-heptanone, cyclohexanone, propylene glycol methyl ether acetate, ethyl lactate, 3 -Ethyl ethoxy propionate, anisole, etc. are mentioned. These organic solvents can be used individually or in combination of 2 or more types.

In these, since the thin film which has a uniform thickness is easy to be obtained, it is preferable to use the thing which has a suitable evaporation rate, specifically the organic solvent whose boiling point is about 70-200 degreeC.

Although the content rate of the organic solvent in the composition for organic electroluminescent element of this invention changes with kinds of the compound component for EL elements and a light emitting component, it is 100-100,000 mass parts with respect to 100 mass parts of compound components for EL elements, and is preferable. Preferably 1,000 to 10,000 parts by mass.

By the content rate of the organic solvent being the said range, the compound for organic electroluminescent elements and phosphorescence-emitting compound of this invention can be melt | dissolved uniformly, and it can form into a preferable film thickness.

Arbitrary additives, such as a charge transport compound, can be added to the composition for organic electroluminescent elements of this invention as needed, for example.

As a specific example of a charge transport compound, the compound which has a charge transport property represented by the following general formula (A-1)-(A-10), and the electron transport property represented by the following general formula (B-1)-general formula (B-20) The compound which has, and the compound which has hole transport property represented by following General formula (C-1)-general formula (C-34), etc. are mentioned.

Here, in general formula (B-16), R <^5> represents either group represented by the following general formula (A)-(C).

Here, in general formula (C-12), m represents an integer of 1 or more.

It is preferable that content of the charge-transporting compound in the organic EL element material composition of this invention is 0-200 weight part with respect to 100 mass parts of compound components for EL elements, More preferably, it is 0-100 weight part.

According to such a composition for organic EL devices, a phosphorescent organic EL device having a light emitting layer having good durability by emitting light with sufficiently high light emission luminance can be obtained, and furthermore, the light emitting layer can be easily formed by a wet method.

As a method of forming a light emitting layer with the said composition for organic electroluminescent elements, after apply | coating the said composition for organic electroluminescent elements to the surface of a suitable base | substrate, it can form by removing an organic solvent.

As a method of apply | coating the composition for organic electroluminescent elements, appropriate methods, such as a spin coating method, an immersion method, a roll coating method, an inkjet method, and a printing method, can be employ | adopted, for example.

Although the thickness of the light emitting layer formed is not specifically limited, Usually, it is selected in the range of 10-200 nm, Preferably it is 30-100 nm.

<Organic EL element>

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing for description which shows an example of the structure of the organic electroluminescent element of this invention.

In the organic EL device of the above example, an anode 2 serving as an electrode for supplying holes is provided on the transparent substrate 1 by, for example, a transparent conductive film, and the hole injection transport layer 3 is formed on the anode 2. Is provided, the light emitting layer 4 is provided on this hole injection transport layer 3, the hole block layer 8 is provided on this light emitting layer 4, and the electron injection water is provided on this hole block layer 8. The sending layer 5 is provided, and the cathode 6 which is an electrode which supplies an electron on this electron injection transport layer 5 is provided. The positive electrode 2 and the negative electrode 6 are electrically connected to the direct current power source 7.

In the organic EL device, a soda glass substrate, a transparent resin substrate, a quartz glass substrate, or the like can be used as the transparent substrate 1.

As the material constituting the anode 2, preferably, a transparent material having a large work function, for example, 4 eV or more is used. Here, the work function refers to the minimum work size required to extract electrons from the solid in vacuum. As the anode 2, for example, an ITO (indium-tin oxide) film, a tin oxide (IV) film, a copper oxide (II) film, a zinc oxide film, or the like can be used.

In addition, although the thickness of the anode 2 changes with kinds of material, it is usually selected in the range of 10-1,000 nm, Preferably it is 50-200 nm.

The hole injection transport layer 3 is provided to supply holes to the light emitting layer 4 efficiently, and has a function of receiving holes (holes) from the anode 2 and transporting them to the light emitting layer 4.

As the material constituting the hole injection transport layer 3, for example, a charge injection transport material such as poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate can be preferably used, and the organic EL of the present invention can also be used. The compound for an element can also be used.

In addition, the thickness of the hole injection transport layer 3 is not particularly limited, but is usually selected in the range of 10 to 200 nm.

The light emitting layer 4 combines electrons and holes, and has a function of emitting the binding energy as light. The light emitting layer 4 is formed of the organic EL device of the present invention or the organic EL device of the present invention. Formed. Here, when the light emitting layer 4 is formed using the composition for organic electroluminescent element of this invention, and contains the compound for organic electroluminescent element of this invention, and a phosphorescent compound, it becomes a phosphorescent organic electroluminescent element especially.

The thickness of the light emitting layer 4 is not particularly limited, but is usually selected in the range of 5 to 200 nm.

The hole block layer 8 suppresses intrusion of holes supplied to the light emitting layer 4 through the hole injection transport layer 3 into the electron injection transport layer 5, thereby recombining holes and electrons in the light emitting layer 4. It has a function which promotes and improves luminous efficiency.

As a material which comprises this hole block layer 8, 2,9- dimethyl- 4,7- diphenyl- 1, 10- phenanthroline (vasocuproline: represented by following General formula (a), for example: BCP), 1,3,5-tri (phenyl-2-benzoimidazolyl) benzene (TPBI), etc. which are represented by following General formula (b) can be used preferably.

In addition, the thickness of the hole block layer 8 is normally selected in the range of 10-100 nm.

The electron injection transport layer 5 has a function of transporting electrons received from the cathode 6 to the light emitting layer 4 through the hole block layer 8. As the material constituting the electron injection transport layer 5, it is preferable to use co-vapor deposition systems (BPCs) of vasophenanthroline-based materials and cesium, and other materials include alkali metals and compounds thereof (for example, lithium fluoride). , Lithium oxide), alkaline earth metals and compounds thereof (for example, magnesium fluoride, strontium fluoride), and the like, and the compound for an organic EL device of the present invention can also be used. The thickness of this electron injection transport layer 5 is usually selected in the range of 0.1 to 100 nm.

As a material which comprises the negative electrode 6, a thing with a small work function, for example, 4 eV or less is used. As a specific example of the negative electrode 6, a metal film containing aluminum, calcium, magnesium, indium, or the like, an alloy film of these metals, or the like can be used.

Although the thickness of the cathode 6 changes with kinds of material, it is normally selected in the range of 10-1,000 nm, Preferably it is 50-200 nm.

In this invention, the said organic electroluminescent element is manufactured as follows, for example. First, the anode 2 is formed on the transparent substrate 1.

As a method of forming the anode 2, a vacuum deposition method, a sputtering method, or the like can be used. Moreover, the commercially available material by which transparent conductive films, such as an ITO film, are formed on the surface of transparent substrates, such as a glass substrate, can also be used.

The hole injection transport layer 3 is formed on the anode 2 thus formed.

As a method of forming the hole injection transport layer 3, specifically, the hole injection transport layer formation liquid is manufactured by dissolving a charge injection transport material in the appropriate solvent, and this hole injection transport layer formation liquid is apply | coated to the surface of the anode 2, The method of forming the hole injection transport layer 3 can be used by performing a solvent removal process with respect to the obtained coating film.

Next, the light emitting layer 4 is formed on the formed hole injection transport layer 3.

As a method of forming the light emitting layer 4, the light emitting layer forming liquid is applied onto the hole injection transport layer 3 by using the composition for organic EL device of the present invention as a light emitting layer forming liquid, for example. The method of forming the light emitting layer 4 can be used by performing a solvent removal process.

In addition, as a method of forming a light emitting layer by the compound for organic electroluminescent element of this invention, the vacuum evaporation method etc. can be used, and the solution which melt | dissolved the said organic electroluminescent element compound in the organic solvent is carried out on the hole injection transport layer (3). The method of forming the light emitting layer 4 can also be used by apply | coating to and heat-processing the obtained coating film. The light emitting layer 4 can also be formed by co-depositing the compound for organic EL device and the phosphorescent compound of the present invention, and the phosphorescent organic EL device can be obtained by forming the light emitting layer 4 by this method.

The hole block layer 8 is formed on the light emitting layer 4 thus formed, and the electron injection transport layer 5 is formed on the hole block layer 8, and the electron injection transport layer 5 is formed. By forming the cathode 6 on), an organic EL device having the structure shown in FIG. 1 is obtained.

As mentioned above, as a method of forming the hole block layer 8, the electron injection transport layer 5, and the cathode 6, dry methods, such as a vacuum deposition method, can be used.

In the above organic EL device, when a DC voltage is applied between the anode 2 and the cathode 6 by the DC power supply 7, the light emitting layer 4 emits light, and the light is injected into the hole injection transport layer 3, It is radiated to the outside through the anode 2 and the transparent substrate 1.

According to the organic electroluminescent element of such a structure, since the light emitting layer 4 is formed of the said organic electroluminescent element compound or the composition for organic electroluminescent element, excellent durability is acquired and also high luminous efficiency is acquired with high luminous brightness. In particular, in the case where the light emitting layer 4 is formed of the organic EL device composition or the organic EL device compound and the phosphorescent compound, more excellent light emission luminance and light emission efficiency can be obtained.

Further, by arranging the hole block layer 8, the coupling of holes from the anode 2 and electrons from the cathode 2 is realized with high efficiency, and as a result, higher emission luminance is obtained. And high luminous efficiency is obtained.

 In the organic EL element having such a configuration, it is preferable that the hole block layer 8 is formed, but the hole block layer 8 may not be disposed.

Moreover, in the organic electroluminescent element of such a structure, the electron block layer may be formed between the hole injection transport layer 3 and the light emitting layer 4 as needed.

This electron block layer has the function of suppressing the invasion of electrons into the hole injection transport layer 3, promoting the coupling of electrons and holes in the light emitting layer 4, and further improving the luminous efficiency.

Examples of the material constituting the electron blocking layer include electrons such as the amine compound represented by the general formulas (C-1) to (C-34), polyvinylcarbazole, and the polymer represented by the following general formula (7). A material having a hole transporting property can be used as compared with the transporting property, and a solvent-insoluble electron block layer can be obtained by adding a crosslinking agent such as a silane coupling agent to these materials. The thickness of this electron block is normally selected in the range of 1-100 nm.

[Wherein R ⁶ represents an alkyl group having 1 to 20 carbon atoms and p is a repeating number]

Hereinafter, although the specific Example of this invention is described, this invention is not limited to these Examples.

(Synthesis example 1 of the compound for organic EL elements)

First, in a 100 mL two-necked flask equipped with a nitrogen introduction tube and a cooling tube, carbazole 5.02 g (30 mmol), 1,3-dibromobenzene 10.62 g (45 mmol), copper iodide 1.71 g (4.5 mmol) ), 12.44 g (90 mmol) of potassium carbonate, 0.37 g (1.4 mmol) of 18-crown-6-ether and 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone 1.35 mL (hereinafter referred to as "DMPU") was added, and the mixture was allowed to react over 6 hours under a nitrogen atmosphere. After the completion of reaction, the mixture was extracted with ethyl acetate and purified by silica column using hexane as a developing solvent to obtain 4.74 g of 9- (3-bromophenyl) -9H-carbazole.

Next, 1.16 g (3.6 mmol) of 9- (3-bromophenyl) -9H-carbazole was added to a 100 mL two-necked flask equipped with a nitrogen introduction tube, and 40 mL of dry diethyl ether was added thereto. It melt | dissolved on the conditions of the temperature of 0 degreeC under nitrogen atmosphere. Then, 1.52 mL (3.96 mmol) was dripped at 2.6 Mn-butyllithium hexane solution, and it stirred for 4 hours. Subsequently, 0.5 g (1.5 mmol) of vasophenanthroline dissolved in 20 mL of dry toluene were added, followed by stirring at room temperature for 48 hours. After the completion of the reaction, the mixture was extracted with methylene chloride, purified by a silica column using a hexane: methylene chloride = 1: 1 mixed solvent as a developing solvent, and further recrystallized with a chloroform / hexane mixed solvent to give white crystals 0.6 as a reaction product. g was obtained. The synthesis process which concerns on the synthesis example 1 of this compound for organic electroluminescent elements is shown by the said Reaction formula (1).

As for the obtained reaction product, ¹ H-NMR spectrum and ¹³ C-NMR (hereinafter referred to as "organic EL element compound (1)") of measuring the spectral bar, the formula (I-8) The compound represented by the It was confirmed.

¹ H-NMR spectral diagram is shown in FIG. 2, and ¹³ C-NMR spectral diagram is shown in FIG.

(Synthesis example 2 of the compound for organic EL elements)

In the synthesis example 1 of the compound for organic electroluminescent element, it carried out similarly to the synthesis example 1 of the compound for organic electroluminescent element, except that 1, 4- dibromobenzene was used instead of 1, 3- dibromo benzene, and as reaction product. 0.68 g of yellow crystals were obtained.

About the obtained reaction product, when it measured ¹ H-NMR spectrum and ¹³ C-NMR spectrum, it is a compound represented by the said General formula (I-7) (henceforth "the compound for organic EL elements (2)"). It was confirmed.

FIG. 4 shows a ¹ H-NMR spectral diagram, and FIG. 5 shows a ¹³ C-NMR spectral diagram.

(Synthesis example 3 of the compound for organic EL elements)

First, in a 100 mL two-necked flask equipped with a nitrogen introduction tube and a cooling tube, 5.08 g (30 mmol) of diphenylamine, 10.62 g (45 mmol) of 1,3-dibromobenzene, and 1.71 g (4.5 mmol) of copper iodide ), 12.44 g (90 mmol) of potassium carbonate, 0.37 g (1.4 mmol) of 18-crown-6-ether and 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone 1.35 mL was added and reacted over 6 hours under nitrogen atmosphere on conditions of the temperature of 170 degreeC. After completion of the reaction, the mixture was extracted with ethyl acetate and purified by silica column using hexane as a developing solvent to obtain 5.0 g of white crystals of 3-bromo-N, N-diphenylaminobenzene.

Next, 3.24 g (10.0 mmol) of 3-bromo-N, N-diphenylaminobenzene was added to a 200 mL three-necked flask equipped with a nitrogen inlet tube, and 80 mL of dry diethyl ether was added thereto, followed by nitrogen. In the atmosphere, it was dissolved at 0 ° C. Then, 4.6 mL (12.0 mmol) was dripped at 2.6 Mn-butyllithium hexane solution, and it stirred for 4 hours. Subsequently, 0.997 g (3.0 mmol) of vasophenanthroline dissolved in 40 mL of dry toluene were added, followed by stirring at room temperature for 48 hours. After the completion of the reaction, the mixture was extracted with methylene chloride, purified by a silica column using a hexane: methylene chloride = 1: 1 mixed solvent as a developing solvent, and further recrystallized with a chloroform / hexane mixed solvent to yield 1.30 g of pale yellow crystals as a reaction product. Got.

About the obtained reaction product, when it measured ¹ H-NMR spectrum and ¹³ C-NMR spectrum, it is a compound represented by the said General formula (I-2) (henceforth "the compound for organic EL elements (3)"). It was confirmed.

FIG. 6 shows a ¹ H-NMR spectrum diagram, and FIG. 7 shows a ¹³ C-NMR spectrum diagram.

(Manufacture example 1 of the composition for organic electroluminescent elements)

0.1 g of an organic EL device compound (2) and an iridium complex compound represented by the following general formula (c) in which x and y are both 0 (hereinafter referred to as "iridium complex compound (1)") By dissolving 0.004 g in 3.4 g of chlorobenzene, the composition for organic electroluminescent elements (A-1) was obtained.

(Manufacture example 2 of the composition for organic electroluminescent elements)

0.1 g of compounds for organic EL elements (3) and 0.004 g of iridium complex compound (1) were dissolved in 3.4 g of chlorobenzene to obtain a composition for organic EL elements (A-2).

Example 1

(Manufacture example 1 of organic electroluminescent element)

An ITO substrate on which an ITO film is formed on a transparent substrate is prepared, and the ITO substrate is ultrasonically cleaned using neutral detergent, ultrapure water, isopropyl alcohol, ultrapure water, and acetone in the above order, and then UV-ozone (UV / O ₃ ).

Subsequently, a poly (3,4-ethylenedioxythiophene) -polystyrenesulfonate aqueous solution was applied onto the ITO substrate by spin coating, and the resulting 65 nm thick coating film was dried at 250 ° C. for 30 minutes under a nitrogen atmosphere. A hole injection transport layer was formed.

On this hole injection transport layer, a composition for organic EL device (A-1) is applied as a light emitting layer forming liquid by spin coating, and a light emitting layer is formed by drying the obtained coating film having a thickness of 40 nm for 10 minutes at 150 ° C. under a nitrogen atmosphere. It was.

Subsequently, the laminate in which the hole injection transport layer and the light emitting layer were laminated in this order on the ITO film was fixed in a vacuum apparatus, the vacuum apparatus was decompressed to 1 × 10 ⁻² Pa or less, and TPBI was deposited to a thickness of 30 nm. After forming a hole block layer, lithium fluoride was deposited to a thickness of 0.5 nm to form an electron injection transport layer, and further, a calcium metal layer of 30 nm thickness and an aluminum metal layer of 100 nm thickness were deposited in this order to form a cathode. It was. Then, the organic electroluminescent element 1 was manufactured by sealing with glass.

(Characteristic evaluation of organic EL element)

As for the obtained organic EL element 1, when the light emitting layer was made to emit light and the maximum light emission luminance and the light emission efficiency were measured, the maximum light emission luminance was 300 Cd / m ² and the light emission efficiency was 8.0 Cd / A.

Example 2

(Manufacture example 2 of organic EL element)

In the manufacture example 1 of the organic electroluminescent element in Example 1, it is the same as the manufacture example 1 of the organic electroluminescent element except having used the composition for organic electroluminescent elements (A-2) instead of the composition for organic electroluminescent elements (A-1). Thus, the organic EL device 2 was manufactured.

 (Characteristic evaluation of organic EL element)

As for the obtained organic EL element 2, when the light emitting layer was made to emit light and the maximum light emission luminance and the light emission efficiency were measured, the maximum light emission luminance was 200 Cd / m ² and the light emission efficiency was 0.3 Cd / A.

Example 3

(Manufacture example 3 of an organic EL element)

After preparing an ITO substrate in which an ITO film is formed on a transparent substrate, and ultrasonically cleaning the ITO substrate using a neutral detergent, ultrapure water, isopropyl alcohol, ultrapure water, and acetone in the above-described order, further ultraviolet-ozone (UV / O ₃ ) washed.

Subsequently, an aqueous poly (3,4-ethylenedioxythiophene) -polystyrenesulfonate aqueous solution is applied onto the ITO substrate by spin coating, and the resulting 65 nm thick coating film is dried at 250 ° C. for 30 minutes in a nitrogen atmosphere. A hole injection transport layer was formed.

On this hole injection transport layer, compound (2) for organic EL device and iridium complex compound (1) are made into 6 mol% with respect to the compound for organic EL device (2), and the concentration of iridium complex compound (1) is 6 mol%. By vapor deposition, a light emitting layer having a thickness of 40 nm was formed.

Subsequently, the laminate in which the hole injection transport layer and the light emitting layer were laminated in this order on the ITO film was fixed in a vacuum apparatus, the vacuum apparatus was decompressed to 1 × 10 ⁻² Pa or less, and TPBI was deposited to a thickness of 30 nm. After forming a hole block layer, lithium fluoride was deposited to a thickness of 0.5 nm to form an electron injection transport layer, and further, a calcium metal layer of 30 nm thickness and an aluminum metal layer of 100 nm thickness were deposited in this order to form a cathode. It was. Then, the organic electroluminescent element 3 was manufactured by sealing with glass.

 (Characteristic evaluation of organic EL element)

As for the obtained organic EL element 3, when the light emitting layer was made to emit light and the maximum light emission luminance and the light emission efficiency were measured, the maximum light emission luminance was 1200 Cd / m ² and the light emission efficiency was 0.2 Cd / A.

Example 4

(Manufacture example 4 of the organic EL element)

In the manufacture example 3 of the organic electroluminescent element in Example 3, it carried out similarly to the manufacture example 1 of the organic electroluminescent element except having used the compound for organic electroluminescent element (1) instead of the compound (2) for organic electroluminescent element, and The EL element 4 was manufactured.

 (Characteristic evaluation of organic EL element)

With respect to the obtained organic EL element 4, the light emitting layer was made to emit light, and the highest light emission luminance and light emission efficiency were measured. The maximum light emission luminance was 1700 Cd / m ² and the light emission efficiency was 0.3 Cd / A.

Example 5

(Manufacture example 5 of an organic EL element)

In the manufacture example 3 of the organic electroluminescent element in Example 3, it carried out similarly to the manufacture example 1 of the organic electroluminescent element except having used the compound for organic electroluminescent element (3) instead of the compound (2) for organic electroluminescent element, and The EL element 4 was manufactured.

(Characteristic evaluation of organic EL element)

With respect to the obtained organic EL element 4, the light emitting layer was made to emit light, and the highest light emission luminance and light emission efficiency were measured. The maximum light emission luminance was 200 Cd / m ² and the light emission efficiency was 0.2 Cd / A.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing for description which shows an example of the structure of the organic electroluminescent element of this invention.

2 is a ¹ H-NMR spectrum diagram according to Synthesis Example 1 of the compound for organic EL devices.

3 is a ¹³ C-NMR spectrum diagram according to Synthesis Example 1 of the compound for organic EL devices.

4 is a ¹ H-NMR spectrum diagram according to Synthesis Example 2 of the compound for organic EL devices.

5 is a ¹³ C-NMR spectrum diagram of Synthesis Example 2 of the compound for organic EL devices.

6 is a ¹ H-NMR spectrum diagram according to Synthesis Example 3 of the compound for organic EL devices.

7 is a ¹³ C-NMR spectrum diagram according to Synthesis Example 3 of the compound for organic EL devices.

FIG. 8 is an explanatory diagram showing the shapes of LUMO and HOMO of the compound for an organic EL device of the present invention represented by the general formula (I-8), calculated by the density functional method using the B3LYP type function.

FIG. 9 is an explanatory diagram showing the shapes of LUMO and HOMO of the compound for an organic EL device of the present invention represented by the general formula (I-2), calculated by the density functional method using the B3LYP type function.

FIG. 10 is an explanatory diagram showing the shapes of LUMO and HOMO of the compound for an organic EL device of the present invention represented by the formula (I-7), calculated by the density functional method using the B3LYP type function.

FIG. 11 shows the shapes of LUMO and H0M0 of BND (2,5-bis (1-naphthyl) -1,3,4-oxadiazole) calculated by the density functional method using the B3LYP type function. It is explanatory drawing.

FIG. 12 shows LUMO and HOMO of α-NPD ([N.N′-di (naphthalen-1-yl) -N.N′-diphenylbenzidine]), calculated by the density functional method using the B3LYP type function. It is explanatory drawing which shows the shape of.

<Explanation of symbols for the main parts of the drawings>

1: transparent substrate

2: anode

3: hole injection transport layer

4: light emitting layer

5: electron injection transport layer

6: cathode

7: DC power

8: hole block layer

Claims (5)

The compound for organic electroluminescent elements which consists of a compound represented by following General formula (I). <Formula (I)>

[Ar ¹ And Ar ² each independently represent a divalent group or a single bond having any one of an aromatic ring, a condensed ring, and a heterocycle in its structure, and Ar ³ and Ar ⁴ each independently represent an aromatic ring, a condensed ring in its structure; And a monovalent group having any one of heterocycles, and Ar ³ and Ar ⁴ bonded to the same nitrogen atom may combine with each other to form a ring structure, and R ¹ is a monovalent organic group, a hydrogen atom or a fluorine atom Indicates 100 mass parts of components containing the compound for organic electroluminescent elements of Claim 1, 1-20 mass parts of components containing a phosphorescent compound, and 100-100,000 mass parts of organic solvents, The organic electric field characterized by the above-mentioned. Light emitting device composition. The organic electroluminescent element which has any one of a hole injection transport layer, the electron injection transport layer, and the light emitting layer formed of the compound for organic electroluminescent elements of Claim 1 characterized by the above-mentioned. The phosphorescent organic electroluminescent element which has a light emitting layer containing the compound for organic electroluminescent elements of Claim 1, and a phosphorescent compound. The phosphorescent organic electroluminescent device according to claim 4, wherein the light emitting layer is formed by using the composition for organic electroluminescent devices according to claim 2.

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