WO2015087795A1

WO2015087795A1 - Organic electroluminescence element, lighting device, and display device

Info

Publication number: WO2015087795A1
Application number: PCT/JP2014/082210
Authority: WO
Inventors: 大野　香織; 貴宗服部
Original assignee: コニカミノルタ株式会社
Priority date: 2013-12-10
Filing date: 2014-12-05
Publication date: 2015-06-18
Also published as: JPWO2015087795A1

Abstract

The present invention addresses the problem of providing an organic EL element in which the change in the resistance value of a light-emitting layer at the time that electric current passes therethrough is small. This organic EL element is characterized by: an organic functional layer that comprises a light-emitting layer being sandwiched between an anode and a cathode; and by at least one layer of the organic functional layer comprising a compound of which the chemical shift value in a ³¹P-NMR spectrum is within the range of 40-48 ppm when dissolved with triethylphosphine oxide in toluene.

Description

Organic electroluminescence element, lighting device and display device

The present invention relates to an organic electroluminescence element, a display device, and a lighting device. More specifically, the present invention relates to an organic electroluminescence element having a small change in resistance value of a light emitting layer over time, and a lighting device and a display device including the organic electroluminescence element.

An organic electroluminescence (EL) element has a configuration in which a light-emitting layer containing an organic compound that emits light is sandwiched between a cathode and an anode, and by applying an electric field, the holes injected from the anode and the cathode This is a light emitting device utilizing excitons (excitons) generated by recombining injected electrons in the light emitting layer, and light emission (fluorescence / phosphorescence) when the excitons are deactivated. The organic EL element is an all-solid-state element composed of an organic material film having a thickness of only a submicron between the electrodes, and can emit light at a voltage of several volts to several tens of volts. It is expected to be used for flat displays and lighting.

As development of an organic EL element for practical use, Princeton University has reported an organic EL element using phosphorescence emission from an excited triplet (for example, see Non-Patent Document 1). Research on materials that exhibit light has become active (see, for example, Patent Document 1 and Non-Patent Document 2). In addition, organic EL elements that utilize phosphorescence emission can in principle achieve light emission efficiency that is approximately four times that of elements that utilize previous fluorescence emission. Research and development of electrode layers and electrodes are conducted all over the world.

The biggest problem in the research and development process is the low durability because the light emitting material and its surrounding materials are organic compounds, and many light emitting materials have been developed to improve the durability. At the same time, however, the importance of host compounds that deliver electrons and holes (collectively referred to as electric charges) to a light-emitting substance has become clear, and its development has been actively conducted (for example, Patent Documents 2 and 3). reference.).

The inventors of the present invention have focused on elucidating the phenomenon in the organic EL element, and analyzed the time-dependent change of the host compound existing in the light emitting layer. As a result, the fundamental factor of various technical problems of the organic EL element is the light emission. It has been found that this is a change in the resistance of the film over time when the layer was energized (emission) and during non-emission storage.

US Pat. No. 6,097,147 JP 2005-112765 A JP 2005-112765 A

The present invention has been made in view of the above-described problems and circumstances, and a solution to the problem is to provide an organic electroluminescence element having a small change in resistance value of a light-emitting layer over time, and an illumination device and a display device including the organic electroluminescence element. It is to be.

Further, as a secondary effect, an organic electroluminescence element having a small voltage increase, a good chromaticity of an emission spectrum and a small change rate of chromaticity, and an illumination device and a display device including the same Is to provide.

In the process of studying the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor in the ³¹ P-NMR spectrum when dissolved in toluene together with triethylphosphine oxide in at least one of the organic functional layers. It has been found that an organic electroluminescence device having a small change in resistance value of the light emitting layer over time can be provided by containing a compound having a chemical shift value within a specific range, and the present invention has been achieved.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. An organic electroluminescence device in which an organic functional layer including a light emitting layer is sandwiched between an anode and a cathode,
At least one layer of the organic functional layer contains a compound having a chemical shift value in the range of 40 to 48 ppm in ³¹ P-NMR spectrum when dissolved together with triethylphosphine oxide in toluene. Organic electroluminescence device.

2. The compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum has an excited triplet state (T ₁ ) energy of 3.00 eV or more and a nitrogen content of 3.0 to 2. The organic electroluminescence device according to item 1, wherein the content is in the range of 15.0%.

3. The light emitting layer contains a complex of iridium or platinum,
3. The organic electroluminescence device according to

item

1 or 2, wherein the complex has a nitrogen content of 10.0 to 30.0% and emits phosphorescence when energized.

4). The light emitting layer contains a fluorescent compound,
The organic electroluminescence device according to any one of items 1 to 3, wherein an internal quantum efficiency in electrical excitation of the fluorescent compound is 50% or more.

5. Items 1 to 4, wherein the compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum is a compound having a structure represented by the following general formula (1): The organic electroluminescent element as described in any one of the above.

(In general formula (1), ring α and ring β are each independently a pyrrole ring, furan ring, thiophene ring, imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole. Represents a ring, a tetrazole ring, an oxazole ring, an isoxazole ring, an oxadiazole ring, a thiazole ring, an isothiazole ring or a thiadiazole ring, and R is linked at an arbitrary position of ring α or ring β. And n represents an integer of 1 to 8.)

6. 6. The organic electroluminescence device according to item 5, wherein the compound having a structure represented by the general formula (1) is a compound having a structure represented by the following general formula (2).

(In general formula (2), ring α, ring β and R have the same meaning as ring α, ring β and R in general formula (1). M represents an integer of 1 to 6. L represents 2) Represents a valent linking group.)

7. The organic electroluminescence device according to any one of items 1 to 6, which emits white light.

8. An illumination device comprising the organic electroluminescence element according to any one of items 1 to 7.

9. A display device comprising the organic electroluminescence element according to any one of items 1 to 7.

By the above means of the present invention, it is possible to provide an organic electroluminescence element having a small change in resistance value of the light emitting layer over time, and an illuminating device and a display device including the organic electroluminescence element.

Furthermore, it is possible to provide an organic electroluminescence element with little increase in voltage, good emission spectrum chromaticity, and low chromaticity change rate, and an illumination device and a display device including the organic electroluminescence element.

The expression mechanism / action mechanism of the effect of the present invention is not clear, but is presumed as follows.

Usually, it has been difficult to measure the resistance of a light emitting layer having a thickness of several tens of nanometers in a light emitting element in a non-destructive manner, but recently it is relatively easy to measure by using impedance spectroscopy. It has become possible to Thereby, it becomes possible to measure the resistance value of the light emitting layer in the state immediately after producing the organic EL element and the resistance value of the light emitting layer during energization and / or non-emission storage time.

As a result of intensive studies, the inventors have found that the smaller the resistance value change, the less the voltage rise of the light emitting element, the better the chromaticity of the emission spectrum, and the smaller the rate of change. .
In order to achieve the present invention, host compounds that reduce the change in resistance as described above were extracted from a number of newly designed host compounds including existing host compounds, and their common physical properties were examined. However, it has been found that a low number of acceptors of the host compound is a condition for the host compound that reduces the change in resistance value by impedance spectroscopy. In addition, by reducing the number of acceptors, the chromaticity of the emission spectrum was improved, and the change with time could be reduced. The greater effect is that the host compound has a structure in which a 5-membered ring and a 5-membered ring are linked, such as a compound having a structure represented by the general formula (1) or (2). However, it has been found that this is a universal technical idea for reducing the change in resistance value of the light emitting layer, and the present invention has been completed.

For this reason, in the present invention, a compound having a low chemical shift value in a ³¹ P-NMR (Nuclear Magnetic Resonance) spectrum within a certain range is used as the host compound as the organic EL device material. That is, as described above, since the host compound having a lower acceptor number is used, the relationship between the number of acceptors / the number of donors between the host compound and the light-emitting dopant is improved, and as a result, the host in the light-emitting layer is obtained. It is considered that the interaction between the compounds and the interaction between the host compound and the light-emitting dopant fall within an appropriate range. As a result, the film quality of the light emitting layer is improved, the resistance value change of the light emitting layer with the passage of time is reduced, voltage rise is suppressed, and further, dopant aggregation is also suppressed, so that chromaticity is improved and light emission is improved. It is inferred that changes in the shape of the spectrum can be suppressed.

Schematic diagram showing energy diagrams of fluorescent compound and TADF compound Schematic of lighting device Cross section of the lighting device Graph showing an example of M-plot with different thickness of electron transport layer Graph showing an example of the relationship between layer thickness and resistance Schematic diagram showing an example of an equivalent circuit model of an organic EL element A graph showing an example of the analysis result of the resistance-voltage relationship of each layer Graph showing an example of analysis results after deterioration Schematic configuration diagram showing the manufacturing process of organic EL full-color display device Schematic configuration diagram showing the manufacturing process of organic EL full-color display device Schematic configuration diagram showing the manufacturing process of organic EL full-color display device Schematic configuration diagram showing the manufacturing process of organic EL full-color display device Schematic configuration diagram showing the manufacturing process of organic EL full-color display device

In the organic EL device of the present invention, an organic functional layer including a light emitting layer is sandwiched between an anode and a cathode, and ³¹ P- when dissolved in toluene together with triethylphosphine oxide in at least one layer of the organic functional layer. A compound having a chemical shift value in the range of 40 to 48 ppm in the NMR spectrum is contained. This feature is a technical feature common to the inventions according to claims 1 to 9.

As an embodiment of the present invention, it is preferable that the nitrogen content of the compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum is in the range of 3.0 to 15.0%, When the content is within this range, the balance of carrier (hole / electron) transportability is maintained while appropriately maintaining the interaction between the host compounds.

In addition, the energy of the excited triplet state (T ₁ ) of the compound is preferably 3.00 eV or more, whereby an energy difference is generated between the light emitting material and the host compound, and the excited triplet of the light emitting material is produced. The probability of undesired reverse energy transfer from the state (T ₁ ) to the host compound is reduced, and sufficient luminous efficiency can be obtained.

The light emitting layer preferably contains a phosphorescent compound (phosphorescent dopant) having a nitrogen content in the range of 10.0 to 30.0%, which increases the luminous efficiency. Become. Further, by using a phosphorescent compound having a nitrogen content in the range of 10.0 to 30.0%, a compound having a chemical shift value in the ³¹ P-NMR spectrum of 40 to 48 ppm is obtained. Since the relationship between the number of acceptors / donors between the host / dopant when used as a host compound is further improved, the interaction between the host compound and the light-emitting dopant is within an appropriate range, and the film quality of the light-emitting layer is improved. The resistance value change of the light emitting layer during energization decreases, voltage increase is suppressed, and further, dopant aggregation is also suppressed, so that chromaticity can be improved and shape change of the emission spectrum can be suppressed. .

In addition, the light emitting layer preferably contains a fluorescent compound, and the internal quantum efficiency in electrical excitation of the fluorescent compound is preferably 50% or more from the viewpoint of luminous efficiency.

^The compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum is a compound having a structure represented by the general formula (1), and the energy of the high excited triplet state (T ₁ ) Carrier adjustment in the organic EL device can be performed by adjusting the energy level of the highest occupied orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). It is preferable because both high luminous efficiency and durability can be realized. In addition, since the compound having the structure represented by the general formula (1) has a mode of being connected by a single bond, the stability and the compound as compared with a monocyclic 5-membered aromatic heterocycle The safety is improved, and it is estimated that the improvement in stability of such a compound itself contributes to the improvement in the durability of the organic EL device.

Furthermore, it is compared with the compound which has a structure represented by General formula (1) that the compound which has a structure represented by General formula (1) is a compound which has a structure represented by General formula (2). In addition, it has higher excited triplet state (T ₁ ) energy and can improve the stability as a compound. When used in an organic EL device, both high luminous efficiency and durability can be achieved. It is preferable because it becomes possible.

The organic EL device of the present invention preferably emits white light.
Moreover, the organic EL element of this invention can be comprised suitably for an illuminating device and a display apparatus.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” representing a numerical range is used in the sense that numerical values described before and after the numerical value range are included as a lower limit value and an upper limit value.

≪ ³¹ P-NMR spectrum≫
In the organic EL device of the present invention, an organic functional layer including a light emitting layer is sandwiched between an anode and a cathode, and ³¹ P when dissolved together with triethylphosphine oxide in toluene in at least one layer of the organic functional layer. -Characterized in that it contains compounds whose chemical shift values in the NMR spectrum are in the range from 40 to 48 ppm.
In the present invention, the chemical shift value in the ³¹ P-NMR spectrum when dissolved together with triethylphosphine oxide in toluene is the interaction value between the triethylphosphine oxide dissolved in toluene and the compound as the measurement object. In the present invention, it is considered as one index representing the number of acceptors of the host compound.

The number of acceptors is a solvent parameter proposed by Gutmann and is understood as a measure of acidity and an electron accepting parameter.
When measuring the number of acceptors of a solvent, the chemical shift value in ³¹ P-NMR spectrum of triethylphosphine oxide ((C ₂ H ₅ ) ₃ PO) dissolved in various solvents is measured. 0,1,2-dichloroethane (SbCl ₅ ) is a value normalized to 100, but cannot be used when it is desired to know the number of individual acceptors. In the present invention, the compound to be measured in toluene is triethyl. The chemical shift value in the ³¹ P-NMR spectrum when dissolved with phosphine oxide was defined as an electron accepting parameter.

In the present invention, it is an essential condition that a compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum when dissolved together with triethylphosphine oxide in toluene is contained. By using a host compound having a chemical shift value of 40 to 48 ppm, which is slightly lower, within a certain range, the interaction between the host compounds in the light emitting layer and the interaction between the host compound and the light emitting dopant are appropriate. Since the film quality of the light-emitting layer is improved, the change in resistance value of the light-emitting layer over time is reduced, voltage increase is suppressed, and further, dopant aggregation is suppressed, thereby improving chromaticity and light emission. It is predicted that changes in the shape of the spectrum can be suppressed.
In the present invention, the chemical shift value of the ³¹ P-NMR spectrum is determined by adding a solution obtained by dissolving triethylphosphine oxide and a compound to be measured (measuring object) in toluene at a molar ratio of 1: 7 into a sample tube. The measurement was performed by JNM-AL400 (400 MHz), manufactured by JEOL.

Further, the nitrogen content of the compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum is preferably in the range of 3.0 to 15.0%.

In addition, the energy of the excited triplet state (T ₁ ) of the compound is preferably 3.00 eV or more, and more preferably 3.10 eV or more. Furthermore, when used simultaneously with the phosphorescent compound described later, it is preferable that the excited triplet state (T ₁ ) energy is higher than that of the phosphorescent compound.
The energy value of the excited triplet state (T ₁ ) is a value calculated using Gaussian 09, which is molecular orbital calculation software manufactured by Gaussian, USA, and B3LYP / 6-31G * is used as a keyword. After the optimization of the molecular structure, the energy of the excited triplet state (T ₁ ) is defined as a calculated value. The background for using this method is that the correlation between the calculated value obtained by this method and the experimental value is high.

The light emitting layer according to the present invention preferably contains a phosphorescent compound (phosphorescent dopant) having a nitrogen content in the range of 10.0 to 30.0%. By using a phosphorescent compound having a high luminous efficiency and a nitrogen content in the range of 10.0 to 30.0%, the chemical shift value in the ³¹ P-NMR spectrum is 40 to 40%. When a compound within the range of 48 ppm is used as the host compound, the relationship between the number of acceptors / the number of donors between the host compound / the light-emitting dopant is further improved, and the interaction between the host compound and the light-emitting dopant is within the appropriate range. . Thereby, since the film quality of the light emitting layer becomes good, the resistance value change of the light emitting layer during energization is reduced, the voltage increase is suppressed, and further, the aggregation of the dopant is also suppressed, thereby improving the chromaticity, It is predicted that changes in the shape of the emission spectrum can be suppressed.

<< Compound having structure represented by general formula (1) >>
In the present invention, the compound having a chemical shift value in the range of 40 to 48 ppm in the ³¹ P-NMR spectrum is preferably a compound having a structure represented by the following general formula (1).

In general formula (1), ring α and ring β are each independently a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, a pyrazole ring, a 1,2,3-triazole ring, or a 1,2,4-triazole ring. , Tetrazole ring, oxazole ring, isoxazole ring, oxadiazole ring, thiazole ring, isothiazole ring or thiadiazole ring, which are linked at an arbitrary position. R represents a substituent substituted at any position of ring α or ring β. n represents an integer of 1 to 8.

In the compound having the structure represented by the general formula (1), the ring α and the ring β are both 5-membered aromatic heterocycles, and the ring α and the ring β are connected by a single bond. It is a feature. By having such a structural formula, it is possible to have high excited triplet state (T ₁ ) energy, and to adjust carrier transport in the organic EL element by adjusting the energy level of HOMO and the energy level of LUMO. This makes it possible to achieve both high luminous efficiency and durability.

R represents a substituent substituted at any position of ring α or ring β. The substituent is not particularly limited as long as it does not inhibit the effect of the present invention. For example, an alkyl group, an alkenyl group, an alkoxy group, an alkynyl group, a carbonyl group, an amino group, a silyl group, a phosphine oxide group, Examples thereof include an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group, and a non-aromatic heterocyclic group. Among them, the substituent is preferably an aryl group, a heteroaryl group, a silyl group, or an alkyl group, more preferably a phenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a triphenylsilyl group, a methyl group, An isopropyl group, more preferably a phenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or a triphenylsilyl group.
These substituents may further have a substituent. Further, the substituents may be connected to each other to form a ring.

N represents an integer of 1 to 8, preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and still more preferably 1 to 3.

The combination of ring α and ring β is not particularly limited, but at least one of them is preferably a nitrogen-containing aromatic heterocycle, and more preferably both are nitrogen-containing aromatic heterocycles.
In addition, the ring α and the ring β may be further linked to each other to form a ring to form a condensed ring structure. The condensed ring structure formed at this time may be a saturated ring, an unsaturated ring or an aromatic ring, but is preferably a saturated ring or an aromatic ring.
Ring α and ring β may be monocyclic or have a condensed ring structure, but at least one of them is preferably monocyclic, and more preferably monocyclic.

<< Compound having structure represented by formula (2) >>
The compound having a structure represented by the general formula (1) is preferably a compound having a structure represented by the following general formula (2).

In general formula (2), ring α, ring β, and R have the same meanings as ring α, ring β, and R in general formula (1). m represents an integer of 1 to 6. L represents a divalent linking group.

L represents a divalent linking group, and connects ring α and ring β, and forms a new ring with ring α and part of ring β and linking group L.
The linking group is not particularly limited as long as the effects of the present invention are not impaired. For example, an alkylene group, an alkenylene group, an ether group, an ester group, a carbonyl group, an amino group, an amide group, a silyl group, and a phosphine Examples thereof include an oxide group, an arylalkylene group, a non-aromatic heterocyclic group, —O—, —S—, or a linking group in which these are arbitrarily combined. Among them, preferred are an alkylene group, an ether group, an ester group, a carbonyl group, an amino group, an amide group, a silyl group, and a phosphine oxide group, and more preferred are an alkylene group, an ether group, an ester group, an amino group, a silyl group, and a phosphine. An oxide group, more preferably an alkylene group or an ether group.

As described above, the compound having the structure represented by the general formula (2) according to the present invention has a second connection by the linking group L in addition to the connection between the ring α and the ring β by a single bond. And a condensed ring is formed by the ring including the ring α, the ring β, and the linking group L. By adopting such a structural formula, the compound has a higher excited triplet state (T ₁ ) energy and stability as a compound as compared with the compound having the structure represented by the general formula (1). Thus, it is considered that, when used in an organic EL element, it is possible to achieve both high luminous efficiency and durability.

The number of rings newly formed by the linking group L is not particularly limited, but is preferably a 5- to 10-membered ring, more preferably a 6- to 8-membered ring, and further preferably a 7-membered ring. preferable. The reason why such a number is preferable is that the mobility of the ring α and the ring β can be adjusted to an appropriate range.
Further, the ring newly formed by the linking group L is not particularly limited to either an unsaturated ring or an aromatic ring, but is more preferably an unsaturated ring.

M represents an integer of 1 to 6, preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and still more preferably 1 or 2.

In the following, compounds having chemical shift values in the range of 40 to 48 ppm in ³¹ P-NMR spectrum (Exemplary Compounds HP-1 to HP-6) and structures represented by the general formula (1) or (2) are shown below. Specific examples of the compounds (Exemplary compounds H1-1 to H1-35 and H2-1 to H2-40) are given, but the present invention is not limited thereto.

The compounds having the structure represented by the general formulas (1) and (2) according to the present invention are disclosed in JP2007-23101A, International Publication No. 2012/051667, Japanese Patent No. 50768891, International Publication No. 20111 /. It can be synthesized with reference to No. 134013 and the like.

The compound having the structure represented by the general formulas (1) and (2) according to the present invention is preferably used as a hole blocking material, an electron blocking material, or a host compound, more preferably used as a host compound. It is.
Moreover, the well-known host compound mentioned later can also be used together as a host compound.

≪Component layer of organic EL element≫
The constituent layers of the organic EL element of the present invention will be described.
As typical element structures in the organic EL element of the present invention, the following structures can be exemplified, but the invention is not limited thereto.

(I) Anode / light emitting layer / cathode (ii) Anode / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / cathode (iv) Anode / hole transport layer / light emitting layer / electron Transport layer / cathode (v) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (vi) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode ( vii) Anode / hole injection layer / hole transport layer / (electron blocking layer /) luminescent layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode

Among these, the configuration (vii) is preferably used, but is not limited thereto. If necessary, a hole blocking layer (also referred to as a hole blocking layer) or an electron injection layer (also referred to as a cathode buffer layer) may be provided between the light emitting layer and the cathode. An electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided therebetween.
The electron transport layer is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Further, the electron transport layer may be composed of a plurality of layers.
The hole transport layer is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer may be composed of a plurality of layers.
In the above-described typical element configuration, the layer excluding the anode and the cathode is also referred to as “organic functional layer”.

≪Tandem structure≫
The organic EL element of the present invention may be a so-called tandem structure element in which a plurality of light emitting units (organic functional layers) including at least one light emitting layer are stacked.
Examples of typical element configurations of the tandem structure include the following configurations.

Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode

Here, the first light emitting unit, the second light emitting unit, and the third light emitting unit may all be the same or different. Further, the two light emitting units may be the same, and the remaining one may be different.

The plurality of light emitting units may be directly stacked or may be stacked via an intermediate layer.
The intermediate layer is generally called an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, or an intermediate insulating layer. It has electrons in the adjacent layer on the anode side and holes in the adjacent layer on the cathode side. A known material structure can be used as long as the layer has a function of supplying.
Examples of materials used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiO _x , VO _x , CuI, InN, GaN, Conductive inorganic compound layers such as CuAlO ₂ , CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ and Al, two-layer films such as Au / Bi ₂ O ₃ , SnO ₂ / Ag / SnO ₂ , ZnO / Multi-layer film such as Ag / ZnO, Bi ₂ O ₃ / Au / Bi ₂ O ₃ , TiO ₂ / TiN / TiO ₂ , TiO ₂ / ZrN / TiO ₂ , fullerenes such as C ₆₀ , conductivity such as oligothiophene Examples include organic layers, conductive organic compound layers such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins and metal-free porphyrins. The present invention is not limited thereto.

Examples of a preferable configuration in the light emitting unit include those obtained by removing the anode and the cathode from the configurations (i) to (vii) mentioned in the above representative device configurations. It is not limited to.

Specific examples of the tandem organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734. Specification, U.S. Pat. No. 6,337,492, International Publication No. 2005/009087, JP-A-2006-228712, JP-A-2006-24791, JP-A-2006-49393, JP-A-2006-49394 JP-A-2006-49396, JP-A-2011-96679, JP-A-2005-340187, JP-A-4711424, JP-A-3496868, JP-A-3848564, JP-A-4421169, No. 2010-192719, Special Elements described in JP2009-076929, JP2008-078414, JP2007-059848, JP2003-272860, JP2003-045676, International Publication No. 2005/094130, etc. Although a structure, a constituent material, etc. are mentioned, this invention is not limited to these.

Hereinafter, each layer constituting the organic EL element of the present invention will be described.

≪Luminescent layer≫
The light emitting layer according to the present invention is a layer that provides a field in which electrons and holes injected from an electrode or an adjacent layer are recombined to emit light via excitons, and the light emitting portion is a layer of the light emitting layer. Even within, it may be the interface between the light emitting layer and the adjacent layer. The structure of the light emitting layer according to the present invention is not particularly limited as long as it satisfies the requirements defined in the present invention.
The total thickness of the light emitting layer is not particularly limited, but it prevents the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color against the drive current. From the viewpoint, it is preferable to adjust within the range of 2 nm to 5 μm, more preferably within the range of 2 to 500 nm, and even more preferably within the range of 5 to 200 nm.
In addition, the thickness of each light emitting layer of the present invention is preferably adjusted within the range of 2 nm to 1 μm, more preferably adjusted within the range of 2 to 200 nm, and further preferably within the range of 3 to 150 nm. Adjusted to
The light emitting layer preferably contains a light emitting dopant (a light emitting dopant compound, a dopant compound, also simply referred to as a dopant) and a host compound (a matrix material, a light emitting host compound, also simply referred to as a host).

≪Luminescent dopant≫
As the luminescent dopant, a fluorescent luminescent dopant (also referred to as a fluorescent dopant or a fluorescent compound) and a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound) are preferably used. In the present invention, it is preferable that at least one light emitting layer contains a phosphorescent light emitting dopant.
The concentration of the luminescent dopant in the luminescent layer can be arbitrarily determined based on the specific dopant used and the requirements of the device, and is contained at a uniform concentration in the thickness direction of the luminescent layer. It may also have an arbitrary concentration distribution.
In addition, a plurality of kinds of light emitting dopants may be used in combination, or a combination of dopants having different structures, or a combination of a fluorescent light emitting dopant and a phosphorescent light emitting dopant may be used. Thereby, arbitrary luminescent colors can be obtained.
The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total of CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.

In the present invention, it is also preferable that the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting dopants having different emission colors and emits white light.
There are no particular limitations on the combination of the light-emitting dopants that exhibit white, and examples include blue and orange, and a combination of blue, green, and red.
The white color in the organic EL device of the present invention means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is x = 0.39 ± 0.09 when the 2 ° viewing angle front luminance is measured by the method described above. Y = 0.38 ± 0.08.

(1.1) Fluorescent Luminescent Dopant The fluorescent luminescent dopant according to the present invention (hereinafter also referred to as “fluorescent dopant”) will be described.
The fluorescent dopant is a compound that can emit light from an excited singlet, and is not particularly limited as long as light emission from the excited singlet is observed.
Examples of the fluorescent dopant include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, pyran derivatives, Examples include cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, and rare earth complex compounds.

In addition, the organic EL device of the present invention preferably contains a fluorescent compound having an internal quantum efficiency of 50% or more by electrical excitation.
Normally, when an electric field is applied to the organic EL element, holes and electrons are injected from the anode and the cathode, respectively, and recombine in the light emitting layer to generate excitons. At this time, since singlet excitons and triplet excitons are generated at a ratio of 25%: 75%, it is known that fluorescence emission can only have an efficiency of up to 25% (for example, “for illumination” Development of Phosphorescent Organic EL Technology for Applied Physics, Vol. 80, No. 4, 2011).

However, various developments have been made to improve the light emission efficiency even in the fluorescence emission type, and a phenomenon in which singlet excitons are generated by collision of two triplet excitons (hereinafter referred to as Triplet-Triple Annihilation: hereinafter, as appropriate). Focusing on Triplet-Triplet Fusion (also referred to as “TTF”), a technology that efficiently raises TTA to increase the efficiency of fluorescent elements has been developed. It is improved to 2 to 3 times that of conventional fluorescent materials.

Further, in recent years, a material having a small difference (ΔEst) between the energy of the excited singlet state (S ₁ ) and the excited triplet state (T ₁ ) (in FIG. 1, ΔEst (TADF) is smaller than ΔEst (F). Is small). Thermally activated delayed fluorescence (also called “thermally excited delayed fluorescence”) using a light-emitting mechanism that utilizes the phenomenon that reverse intersystem crossing from triplet excitons to singlet excitons occurs. Say: Thermally Activated Delayed Fluorescence (hereinafter abbreviated as “TADF” where appropriate) has been reported for use in organic EL devices (for example, Proceedings of the 10th Annual Meeting of the Organic EL Discussion P11-12) , 2010), the use of delayed fluorescence by this TADF mechanism enables theoretically 100% internal quantum efficiency even in fluorescence emission. It is believed that.

The use of a fluorescent compound having an internal quantum efficiency of 50% or more by electrical excitation is to use a fluorescent dopant using such TTA or TADF. Of course, the use of fluorescent emission-type dopants improves the efficiency. By combining these dopants with the host compound in the present invention, collision of two triplet excitons in these phenomena. In addition, it is considered that reverse intersystem crossing from triplet excitons to singlet excitons is more likely to occur. Specific examples of the luminescent dopant using delayed fluorescence include, for example, compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like. Is not limited to these.

Specific examples (F-1 to F-20) of fluorescent light emitting compounds (fluorescent light emitting dopants) preferably used in the present invention are shown below.

(1.2) Phosphorescence-emitting dopant The phosphorescence-emitting compound (phosphorescence-emitting dopant) suitably used in the present invention will be described.
The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield of 25. Although it is defined as a compound of 0.01 or more at ° C., a preferable phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

There are two types of emission principles of the phosphorescent dopant.
One is that the recombination of the carrier occurs on the host compound to which the carrier is transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant to obtain light emission from the phosphorescent dopant. It is mobile.
The other is a carrier trap type in which the phosphorescent dopant becomes a carrier trap, and recombination of carriers occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained.
In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL device.
Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
For example, Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Application Publication No. 2006/835469, US Patent Application Publication No. 2006 /. No. 0202194, U.S. Patent Application Publication No. 2007/0087321, U.S. Patent Application Publication No. 2005/0244673, Inorg. Chem. 40, 1704 (2001), Chem. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chem. Lett. 34, 592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Application Publication No. 2002/0034656, and US Pat. No. 7,332,232. US Patent Application Publication No. 2009/0108737, US Patent Application Publication No. 2009/0039776, US Patent No. 6921915, US Patent No. 6,687,266, US Patent Application Publication No. 2007/0190359. Specification, US Patent Application Publication No. 2006/0008670, US Patent Application Publication No. 2009/0165846, US Patent Application Publication No. 2008/0015355, US Patent No. 7250226, US Patent No. No. 7396598 , U.S. Patent Application Publication No. 2006/0263635, U.S. Patent Application Publication No. 2003/0138657, U.S. Patent Application Publication No. 2003/0152802, U.S. Patent No. 7090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Application Publication No. 2006/0251923, US Patent Application Publication No. 2005/0260441, US Pat. No. 7,393,599. Description, US Pat. No. 7,534,505, US Pat. No. 7,445,855, US Patent Application Publication No. 2007/0190359, US Patent Application Publication No. 2008/0297033, US Pat. No. 7,338,722 , US special Published Patent Application No. 2002/0134984, U.S. Pat. No. 7,279,704, U.S. Patent Application Publication No. 2006/098120, U.S. Patent Application Publication No. 2006/103874, International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, Japanese Patent Application Laid-Open No. 2012-069737, Japanese Patent Application No. 2011 -18 303 No., a JP 2009-114086, JP 2003-81988, JP 2002-302671, JP 2002-363552 Patent Publication.

Among them, a preferable phosphorescent dopant includes an organometallic complex having iridium (Ir) as a central metal. More preferably, a complex containing at least one coordination mode of metal-carbon bond, metal-nitrogen bond, metal-oxygen bond, and metal-sulfur bond is preferable.

Particularly, the phosphorescent dopant preferably used in the present invention has a structure represented by the following general formula (DP).

In General Formula (DP), M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os. A ₁ , A ₂ , B ₁ and B ₂ each independently represent a carbon atom or a nitrogen atom. Ring Z ₁ represents a 6-membered aromatic hydrocarbon ring formed together with A ₁ and A ₂ or a 5-membered or 6-membered aromatic heterocycle. Ring Z ₂ represents a 5-membered or 6-membered aromatic heterocycle formed together with B ₁ and B ₂ . L ′ represents a monoanionic bidentate ligand coordinated to M. m ′ represents an integer of 0 to 2, n ′ represents an integer of 1 to 3, and m ′ + n ′ is 2 or 3. When m ′ or n ′ is 2 or more, the ligands or L ′ represented by ring Z ₁ or ring Z ₂ may be the same or different.

M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os, preferably Ir, Pt, Rh, Ru, or Os, and more preferably Ir, Pt, or Os.

Ring Z ₂ is preferably a 5-membered aromatic heterocyclic ring, and at least one of B ₁ and B ₂ is preferably a nitrogen atom.

Ring Z ₁ and ring Z ₂ may have a substituent, and examples of the substituent include the same substituents as the substituents that the ring α and ring β in the general formula (1) may have. . Moreover, the substituents in the ring Z ₁ and the ring Z ₂ may further be bonded to each other to form a condensed ring structure.
Moreover, the substituent of each ligand may mutually couple | bond together and the ligands may connect.

The phosphorescent dopant having a structure represented by the above general formula (DP) is preferably a phosphorescent dopant having a structure represented by the following general formula (DP-1) or (DP-2).

In general formula (DP-1), M, A ₁ , A ₂ , B ₁ , B ₂ , ring Z ₁ , L ′, m ′ and n ′ are M, A ₁ , A ₂ in general formula (DP). , B ₁ , B ₂ , ring Z ₁ , L ′, m ′ and n ′. B ₃ to B ₅ are an atomic group that forms an aromatic heterocyclic ring together with B ₁ and B ₂ , and each represents an optionally substituted carbon atom, nitrogen atom, oxygen atom, or sulfur atom.

Examples of the substituent that B ₃ to B ₅ may have include the same substituents as the substituents that the ring Z ₁ and ring Z ₂ in the general formula (DP) may have.

The aromatic heterocycle formed by B ₁ to B ₅ in the general formula (DP-1) is represented by any of the following general formulas (DP-1a), (DP-1b), or (DP-1c) And is more preferably represented by the general formula (DP-1c).

In the general formulas (DP-1a), (DP-1b), and (DP-1c), * ₁ represents a binding site with A ₂ and * ₂ represents a binding site with M. Rb ₃ to Rb ₅ represent a hydrogen atom or a substituent. B ₄ and B ₅ in the general formula (DP-1a) each independently represent a carbon atom or a nitrogen atom. B ₃ and B ₄ in the general formula (DP-1c) each independently represent a carbon atom or a nitrogen atom.

Examples of the substituent represented by Rb ₃ to Rb ₅ include the same substituents as the substituents that the ring Z ₁ and the ring Z ₂ in the general formula (DP) may have.

B ₄ and B ₅ in the general formula (DP-1a) each independently represent a carbon atom or a nitrogen atom, but preferably at least one is a carbon atom.

B ₃ and B ₄ in the general formula (DP-1c) each independently represent a carbon atom or a nitrogen atom, but at least one is a carbon atom, and a substituent represented by Rb ₃ and Rb ₄ is further It is preferable that they are bonded to each other to form a condensed ring structure. In this case, the newly formed condensed ring structure is preferably an aromatic ring, and more preferably any one of a benzimidazole ring, an imidazopyridine ring, an imidazopyrazine ring, and a purine ring.

Rb ₅ is preferably an alkyl group or an aryl group, and more preferably a phenyl group.

In general formula (DP-2), M, A ₁ , A ₂ , B ₁ , B ₂ , ring Z ₁ , L ′, m ′ and n ′ are M, A ₁ , A ₂ in general formula (DP). , B ₁ , B ₂ , ring Z ₁ , L ′, m ′ and n ′. Ring Z ₂ represents a 5-membered aromatic heterocycle formed together with B ₁ to B ₃ . A ₃ and B ₃ each independently represents a carbon atom or a nitrogen atom. L ″ represents a divalent linking group.

Examples of the divalent linking group represented by L ″ include an alkylene group, an alkenylene group, an arylene group, a heteroarylene group, a divalent heterocyclic group, —O—, —S—, or any combination thereof. Linking groups and the like.

The phosphorescent dopant having a structure represented by the general formula (DP-2) is preferably a phosphorescent dopant having a structure represented by the following general formula (DP-2a).

In general formula (DP-2a), M, A ₁ , A ₂ , B ₁ , B ₂ , ring Z ₁ , ring Z ₂ , L ′, m ′ and n ′ are M in general formula (DP-2). , A ₁ , A ₂ , B ₁ , B ₂ , ring Z ₁ , ring Z ₂ , L ′, m ′ and n ′. L ″ ₁ and L ″ ₂ each independently represent C—Rb ₆ or a nitrogen atom. Rb ₆ represents a hydrogen atom or a substituent.

Examples of the substituent represented by Rb ₆ include the same substituents as the substituents that the ring Z ₁ and the ring Z ₂ in the general formula (DP) may have.

When L ″ ₁ and L ″ ₂ both represent C—Rb ₆ , Rb ₆ may be bonded to each other to form a ring.

In the general formulas (DP), (DP-1), (DP-2), and (DP-2a), A ₂ is preferably a carbon atom, and more preferably A ₁ is a carbon atom. More preferably, the ring Z ₁ is a substituted or unsubstituted benzene ring or pyridine ring, and particularly preferably a benzene ring.

Here, specific examples (D-1 to D-82) of phosphorescent dopants that can be used in the present invention are listed, but the present invention is not limited thereto.

(2) Host Compound The host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light emitting layer, and light emission of itself is not substantially observed in the organic EL device.
Preferably, it is a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), more preferably a compound having a phosphorescence quantum yield of less than 0.01.
Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.
The excited state energy of the host compound is preferably higher than the excited state energy of the light-emitting dopant contained in the same layer.
A host compound may be used independently or may be used in combination of multiple types. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.

There is no restriction | limiting in particular as a host compound which can be used by this invention, Although the compound conventionally used with an organic EL element can be used, It is a compound which has a structure represented by General formula (1) or (2). Preferably there is. Further, it may be a low molecular compound or a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.
As a known host compound, while having a hole transporting ability or an electron transporting ability, it is possible to prevent the emission of light from being long-wavelength, and furthermore, the organic EL element is stable against heat generation during driving at a high temperature or during driving of the element. From the viewpoint of operating, it is preferable to have a high glass transition temperature (Tg). Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
Here, the glass transition point (Tg) is a value obtained by a method based on JIS K 7121 using DSC (Differential Scanning Calorimetry).

Specific examples of known host compounds used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
For example, Japanese Patent Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. No. 2002-302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, No. 2003/0175553, No. 2006/0280965. US Patent Application Publication No. 2005/0112407, US Patent Application Publication No. 2009/0017330, US Patent Application Publication No. 2009/0030202, US Patent Application Publication No. 2005/0238919 ,Country Public Publication No. 2001/039234, International Publication No. 2009/021126, International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005/089025, International Publication No. 2007/063796, International Publication No. 2007/063754, International Publication No. 2004/107822, International Publication No. 2005/030900, International Publication No. 2006/114966, International Publication No. 2009/086028, International Publication No. 2009/003898, International Publication No. 2012/0038 / No. 023947, Japanese Patent Application Laid-Open No. 2008-0749939, Japanese Patent Application Laid-Open No. 2007-254297, European Patent No. 2034538, and the like.

≪Electron transport layer≫
In the present invention, the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
The total thickness of the electron transport layer of the present invention is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.

Also, in the organic EL element, when light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to cause. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between several nanometers and several micrometers.
On the other hand, since the voltage tends to increase when the thickness of the electron transport layer is increased, the electron mobility of the electron transport layer is 1 × 10 ⁻⁵ cm ² / Vs or more, particularly when the layer thickness is large. Is preferred.

The material used for the electron transport layer (hereinafter referred to as an electron transport material) may have any of an electron injecting property, a transporting property, and a hole blocking property. Any one can be selected and used.
For example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, And dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.).

In addition, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7- Dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and their metal complexes A metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.

In addition, metal-free or metal phthalocyanine, or those in which the terminal thereof is substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. Further, a distyrylpyrazine derivative used as a material for the light-emitting layer can also be used as an electron transport material, and an inorganic material such as n-type-Si, n-type-SiC, etc., like the hole injection layer and the hole transport layer. A semiconductor can also be used as an electron transport material.
Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In the electron transport layer in the present invention, a high n-type (electron rich) electron transport layer may be formed by doping a dopant into the electron transport layer as a guest material. Examples of the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides. Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.

Specific examples of known preferable electron transport materials used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
For example, US Pat. No. 6,528,187, US Pat. No. 7,230,107, US Patent Application Publication No. 2005/0025993, US Patent Application Publication No. 2004/0036077, US Patent Application Publication No. 2009/0115316. No., U.S. Patent Application Publication No. 2009/0101870, U.S. Patent Application Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79,156 (2001), U.S. Patent No. 7964293, U.S. Patent Application Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387. , International Publication No. 2006/067931, International Publication No. 2007/085652, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. Japanese Patent Publication No. 2011-086935, International Publication No. 2010/150593, International Publication No. 2010/047707, European Patent No. 2311826, Japanese Unexamined Patent Publication No. 2010-251675, Japanese Unexamined Patent Publication No. 2009-209133, Japanese Unexamined Patent Publication No. 2009. -1241 No. 4, JP 2008-277810 A, JP 2006-156445 A, JP 2005-340122 A, JP 2003-45662 A, JP 2003-31367 A, JP 2003-282270 A. Gazette, International Publication No. 2012/115034, and the like.

More preferable electron transport materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.

The electron transport material may be used alone or in combination of two or more.

≪Hole blocking layer≫
The hole blocking layer is a layer having the function of an electron transport layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved.
Moreover, the structure of the above-mentioned electron carrying layer can be used as a hole-blocking layer as needed.
The hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
The thickness of the hole blocking layer is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As a material used for a hole-blocking layer, the material used for the above-mentioned electron carrying layer is used preferably, and the material used as the above-mentioned host compound is also preferably used for a hole-blocking layer.

≪Electron injection layer≫
An electron injection layer (also referred to as a “cathode buffer layer”) is a layer provided between a cathode and a light emitting layer to reduce driving voltage or improve light emission luminance. (November 30, 1998, issued by NTS Corporation) ”, Volume 2, Chapter 2,“ Electrode Materials ”(pages 123-166).
In the present invention, the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 0.1 to 5 nm, depending on the material. Moreover, the nonuniform film | membrane in which a constituent material exists intermittently may be sufficient.
Details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq), and the like. Further, the above-described electron transport material can also be used.
Moreover, the material used for said electron injection layer may be used independently, and may be used in combination of multiple types.

≪Hole transport layer≫
In the present invention, the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
The total thickness of the hole transport layer of the present invention is not particularly limited, but is usually in the range of 5 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.

As a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT: PSS, aniline copolymer, polyaniline, polythiophene, etc.).
Examples of the triarylamine derivative include a benzidine type typified by α-NPD, a starburst type typified by MTDATA, and a compound having fluorene or anthracene in the triarylamine linking core part.
In addition, hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as hole transport materials.

Furthermore, a hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC, as described in the literature (Applied Physics Letters 80 (2002), p. 139). Further, ortho-metalated organometallic complexes having Ir or Pt as a central metal as typified by Ir (ppy) ₃ are also preferably used.

Although the above-mentioned materials can be used as the hole transport material, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain. The polymer materials or oligomers used are preferably used.

Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not.
For example, Appl. Phys. Lett. 69, 2160 (1996), J. MoI. Lumin. 72-74,985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chem. 3,319 (1993), Adv. Mater. 6, 677 (1994), Chem. Mater. 15, 3148 (2003), U.S. Patent Application Publication No. 2003/0162053, U.S. Patent Application Publication No. 2002/0158242, U.S. Patent Application Publication No. 2006/0240279, U.S. Patent Application Publication No. 2008/2008. No. 0220265, US Pat. No. 5,061,569, WO 2007/002683, WO 2009/018009, EP 650955, US Patent Application Publication No. 2008/0124572, US Japanese Patent Application Publication No. 2007/0278938, US Patent Application Publication No. 2008/0106190, US Patent Application Publication No. 2008/0018221, International Publication No. 2012/115034, and Japanese Translation of PCT International Publication No. 2003-519432. , JP 2006- 35145 JP is US Patent Application Publication No. 2013/585981 Pat like.

The hole transport material may be used alone or in combination of two or more.

≪Electron blocking layer≫
The electron blocking layer is a layer having a function of a hole transport layer in a broad sense, and is preferably made of a material having a function of transporting holes and a small ability to transport electrons, while transporting holes. By blocking electrons, the probability of recombination of electrons and holes can be improved.
Moreover, the structure of the positive hole transport layer mentioned above can be used as an electron blocking layer according to the present invention, if necessary.
The electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
The thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the electron blocking layer.

≪Hole injection layer≫
The hole injection layer (also referred to as “anode buffer layer”) is a layer provided between the anode and the light-emitting layer in order to lower the drive voltage and improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of Volume 2 of “Front Line (published by NTT Corporation on November 30, 1998)”.
In the present invention, the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc. Examples of materials used for the hole injection layer include: And materials used for the hole transport layer described above.
Among them, phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives as described in JP-T-2003-519432, JP-A-2006-135145, etc., metal oxides typified by vanadium oxide, amorphous Conductive polymers such as carbon, polyaniline (emeraldine) and polythiophene, orthometalated complexes represented by tris (2-phenylpyridine) iridium complex, and triarylamine derivatives are preferred.
The materials used for the hole injection layer may be used alone or in combination of two or more.

≪Contents≫
The organic functional layer according to the present invention may further contain other inclusions.
Examples of the inclusion include halogen elements such as bromine, iodine and chlorine, halogenated compounds, alkali metals such as Pd, Ca, and Na, alkaline earth metals, transition metal compounds, complexes, and salts.
The content of the inclusions can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 50 ppm or less with respect to the total mass% of the contained layer. .
However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of favoring the exciton energy transfer.

≪Method of forming organic layer≫
A method for forming an organic functional layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) according to the present invention will be described.

There is no restriction | limiting in particular in the formation method of an organic functional layer, A conventionally well-known formation method can be used, For example, a vacuum evaporation method, a wet method (it is also called a wet process) etc. are mentioned.
Examples of the wet method include spin coating method, casting method, ink jet method, printing method, die coating method, blade coating method, roll coating method, spray coating method, curtain coating method, and LB method (Langmuir-Blodgett method). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method and a spray coating method is preferable.

Examples of the liquid medium for dissolving or dispersing the organic EL material include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, mesitylene, cyclohexylbenzene and the like. Aromatic hydrocarbons, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.
Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

Further, different film formation methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally the boat heating temperature is 50 to 450 ° C., the degree of vacuum is 1 × 10 ⁻⁶ to 1 × 10 ⁻² Pa, and the vapor deposition rate. It is desirable to select appropriately within a range of 0.01 to 50 nm / second, a substrate temperature of −50 to 300 ° C., and a layer thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm.

In the formation of the organic functional layer according to the present invention, it is preferable to consistently produce from the hole injection layer to the cathode by one evacuation, but it may be taken out halfway and subjected to different film forming methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.

≪Anode≫
As the anode in the organic EL element, those having a work function (4 eV or more, preferably 4.5 V or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material are preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used.

For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when the pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered.
Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used.

When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less.
Although the film thickness of the anode depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

≪Cathode≫
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, aluminum, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, A magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum, or the like is preferable.

The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected within the range of 10 nm to 5 μm, preferably 50 to 200 nm.

In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.
In addition, a transparent or translucent cathode can be produced by producing a conductive transparent material mentioned in the description of the anode on the cathode after producing the above metal with a thickness of 1 to 20 nm. By applying the above, it is possible to manufacture a device in which both the anode and the cathode are transparent.

≪Support substrate≫
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. Or opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin film material include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose acetate propionate. (CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, Polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyether imide, polyether ketone imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic or polyarylate, arton (trade name, manufactured by JSR) or appel (trade name, manufactured by Mitsui Chemicals) Resin etc. are mentioned.

The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , And a relative humidity (90 ± 2)% RH) of 0.01 g / (m ² · 24 h) or less is preferable. Further, the film was measured by a method according to JIS K 7126-1987. It is a high gas barrier film having an oxygen permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less and a water vapor permeability of 1 × 10 ⁻⁵ g / (m ² · 24 h) or less. Is preferred.

As a material for forming the gas barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Furthermore, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the gas barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.

The external extraction efficiency at room temperature (25 ° C.) of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
Here, external extraction quantum efficiency (%) = (number of photons emitted to the outside of the organic EL element / number of electrons flowed to the organic EL element) × 100.

Also, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.

≪Sealing≫
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive. As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and it may be concave plate shape or flat plate shape. Moreover, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Further, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less, and a method according to JIS K 7129-1992. the measured water vapor transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably that of ^{^{1 × 10 -3 g / (m}} 2 / 24h) or less.

For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of adhesives include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature (25 degreeC) to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print it like screen printing.

In addition, the electrode and the organic functional layer are coated on the outside of the electrode facing the support substrate with the organic functional layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. Can also be suitably used. In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause element degradation such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.

Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. There are no particular limitations on the method of forming these films. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

≪Protective film, protective plate≫
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided outside the sealing film or sealing film on the side facing the support substrate with the organic functional layer interposed therebetween. In particular, when sealing is performed with a sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for sealing can be used. It is preferable to use it.

≪Light extraction≫
An organic EL element emits light inside a layer having a refractive index higher than that of air (within a refractive index of about 1.6 to 2.1), and is about 15% to 20% of light generated in the light emitting layer. It is generally said that it can only be taken out. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the element, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light, the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the side surface direction of the element.

As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-134795), a method for forming a reflective surface on the side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Application Laid-Open No. 62-172691), lower than the substrate between the substrate and the light emitter. A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), and forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside). Method (JP No. 11-283751 Publication), and the like.

In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, A method of forming a diffraction grating between any one of the transparent electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

If a medium with a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a lower efficiency of extraction to the outside as the refractive index of the medium is lower. Get higher.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally in the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less, preferably 1.35 or less. Is more preferable.

Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.

The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction, such as first-order diffraction or second-order diffraction. The light that cannot be emitted outside due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode) It tries to take out light.
The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
The position where the diffraction grating is introduced may be in any interlayer or medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of light in the medium. The arrangement of the diffraction gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

≪Condenser sheet≫
The organic EL device of the present invention can be processed, for example, by providing a structure on a microlens array on the light extraction side of the support substrate (substrate), or combined with a so-called condensing sheet, for example, in a specific direction, By condensing in the front direction with respect to the element light emitting surface, the luminance in a specific direction can be increased.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably within a range of 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

As the condensing sheet, it is possible to use, for example, a sheet that has been put to practical use in an LED backlight of a liquid crystal display device. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

Further, in order to control the light emission angle from the organic EL element, a light diffusing plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

≪Usage≫
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Examples include, but are not limited to, a light source of a sensor. In particular, the light source can be effectively used for a backlight of a liquid crystal display device and a light source for illumination.

In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned, and a conventionally known method is used in the fabrication of the element. be able to.

≪One aspect of lighting device≫
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.
The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX Track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, as shown in FIGS. Can be formed.

FIG. 2 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is to bring the organic EL element 101 into contact with the atmosphere. And a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).
3 shows a cross-sectional view of the lighting device. In FIG. 3, reference numeral 105 denotes a cathode, reference numeral 106 denotes an organic EL layer, and reference numeral 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

≪Example of thin film resistance measurement by impedance spectroscopy≫
In the impedance spectroscopy (IS) method, a small sine wave voltage signal is applied to an organic EL element, impedance is calculated from the amplitude and phase of the response current signal, and an impedance spectrum obtained as a function of the frequency of the applied voltage signal. Therefore, it is a technique that can analyze subtle changes in physical properties of organic EL elements. It is characterized in that a highly sensitive resistance value (R) and capacitance (C) can be measured without destroying the organic EL element.

The display of the obtained impedance (Z) on the complex plane with the frequency of the applied voltage signal as a parameter is called a Cole-Cole plot. Furthermore, the basic transfer functions, such as modulus (M), admittance (Y), and dielectric constant (ε), can be obtained from this impedance (see “Thin Film Evaluation Handbook”, published by Techno Systems, Inc., pages 423-425). . For example, the modulus is obtained by the following equation.

M = jωZ
In the formula, j represents an imaginary unit and ω = 2πf (f is a frequency).

From these four transfer functions, a transfer function suitable for the purpose of analysis can be selected as appropriate. In the evaluation of organic EL elements, M plots in which the modulus is plotted on a complex plane are often used.

In the present invention, an M plot (M-plot) in which the reciprocal of the capacitance component is known is employed. In this M-plot, since the diameter of the arc portion is approximately the reciprocal of the capacitance of the corresponding layer, it is proportional to the layer thickness, so that the deviation of the layer thickness can also be detected.

In the IS analysis, an equivalent circuit of the organic electroluminescence element is estimated from the locus of the Cole-Cole plot, and the equivalent circuit is determined by matching the locus of the Cole-Cole plot calculated from the equivalent circuit with the measurement data. It is common.

The IS measurement can be performed, for example, using a Solartron 1260 type impedance analyzer and a 1296 type dielectric constant measurement interface, with 30 to 100 mVrms alternating current (frequency range 0.1 mHz to 10 MHz) superimposed on the direct current voltage. .
For the equivalent circuit analysis, ZView manufactured by Scribner Associates can be used.

For organic EL elements (element configuration “ITO / HIL (hole injection layer) / HTL (hole transport layer) / EML (light emitting layer) / ETL (electron transport layer) / EIL (electron injection layer) / Al”) A method for obtaining the resistance value of a specific layer by applying impedance spectroscopy will be described.
For example, when measuring the resistance value of the electron transport layer (ETL), a device in which only the thickness of the ETL is changed is manufactured, and each portion of the curve drawn by the plot is determined by comparing each M-plot. Whether it corresponds to ETL can be determined.

FIG. 4 is an example of an M-plot with a different thickness of the electron transport layer. An example in which the layer thickness is 30 nm, 45 nm, and 60 nm, respectively, is shown. The vertical axis represents the imaginary part M ″ (1 / nF), and the horizontal axis represents the real part M ′ (1 / nF).

FIG. 5 shows the resistance value (R) obtained from this plot plotted against the ETL layer thickness. Since the relationship between the ETL layer thickness and the resistance value (Resistance) lies on a substantially straight line, the resistance value at each layer thickness can be determined.

FIG. 7 shows the result of analyzing each layer using an organic EL element having an element configuration “ITO / HIL / HTL / EML / ETL / Al” as an equivalent circuit model (FIG. 6). FIG. 7 is an example showing the resistance-voltage relationship of each layer.

On the other hand, after the same organic EL element was deteriorated by emitting light for a long time, it was measured under the same conditions, and they were superimposed on each other, and FIG. 8 shows the respective values at a voltage of 1V. FIG. 8 is an example showing an analysis result of the organic EL element after deterioration.

In the organic EL element after deterioration, it can be seen that only the ETL has a resistance value greatly increased due to the deterioration, and the resistance value is about 30 times at a DC voltage of 1V.

By using the above method, it is possible to measure the resistance change before and after energization described in the embodiment of the present invention.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.
The structures of the compounds used in the examples are shown below.

[Example 1]
<< Measurement of chemical shift value of ³¹ P-NMR spectrum >>
The chemical shift values of ³¹ P-NMR spectra of Exemplified compounds HP-5, HP-6 and H1-17 according to the present invention and Comparative compounds 1 to 3 were measured.
Specifically, the chemical shift value of the ³¹ P-NMR spectrum of each compound was determined by adding a solution obtained by dissolving triethylphosphine oxide and each compound in toluene at a molar ratio of 1: 7 into a sample tube, and adding JEOL JNM-AL400 ( 400 MHz), measured by JEOL.
The measurement results are shown in Table 2.

[Example 2]
<< Production of organic EL elements >>
(1) Production of Organic EL Element 1-1 As an anode, patterning was performed on a substrate (NA45 manufactured by NH Techno Glass) on which a 100 nm × 100 mm × 1.1 mm glass substrate of ITO (indium tin oxide) was formed to a thickness of 100 nm. Thereafter, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) diluted to 70% with pure water at 3000 rpm, A thin film was formed by spin coating under conditions of 30 seconds, and then dried at 200 ° C. for 1 hour to provide a hole injection layer having a layer thickness of 20 nm.

This transparent support substrate was fixed to a substrate holder of a commercially available vacuum evaporation apparatus. Meanwhile, 200 mg of α-NPD was put in a molybdenum resistance heating boat, and 200 mg of Comparative Compound A was put in another resistance heating boat made of molybdenum. 200 mg of dopant D-63 was placed in a molybdenum resistance heating boat, and 200 mg of BCP was placed in another molybdenum resistance heating boat, and attached to a vacuum deposition apparatus.

Next, the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁴ Pa, and the heating boat containing α-NPD was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second. A hole transport layer having a thickness of 30 nm was provided.

Further, the heating boat containing the comparative compound A and the heating boat containing the dopant D-63 were energized and heated, and the vapor deposition rates were 0.1 nm / second and 0.010 nm / second, respectively. Evaporation was performed to provide a light emitting layer having a layer thickness of 40 nm.

Furthermore, the heating boat containing BCP was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / second to provide an electron transport layer having a layer thickness of 30 nm.

Subsequently, lithium fluoride was vapor-deposited as an electron injection layer with a thickness of 0.5 nm, and aluminum was vapor-deposited with a thickness of 110 nm to form a cathode, whereby an organic EL element 1-1 was produced.

(2) Preparation of organic EL elements 1-2 to 1-14 Organic EL elements were prepared in the same manner as in the preparation of organic EL elements 1-1 except that the dopant materials and host materials were changed to the compounds shown in Table 3. 1-2 to 1-14 were produced.

<< Evaluation of organic EL elements >>
When evaluating each produced organic EL element, the non-light emitting surface of each produced organic EL element is covered with a glass cover, and the glass cover side surroundings where the glass cover and the glass substrate on which the organic EL element is produced are in contact with each other An epoxy photo-curing adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing agent to the cathode side, and this is placed in close contact with the transparent support substrate, and the organic EL element is removed from the glass substrate side 2 is cured by sealing with UV light, and the illumination device as shown in FIGS. 2 and 3 is manufactured. The resistance value of the light emitting layer is measured by the impedance spectrometer and half of the emission spectrum of the organic EL element. The change rate of the value range was measured.
The following evaluation was performed for each sample thus produced.

(1) Change rate of resistance value before and after driving of organic EL element Refer to the measurement method described in pages 423 to 425 of “Thin Film Evaluation Handbook” published by Technosystem, Inc. Solartron 1260 type impedance analyzer and 1296 type dielectric Using the interface, the resistance value of the light emitting layer of each manufactured organic EL element was measured at a bias voltage of 1 V.
The organic EL element was measured for the resistance value of the light emitting layer before and after driving for 1000 hours under room temperature (25 ° C.) and constant current conditions of ^2.5 mA / cm ² , and the calculation results are shown below. The change rate of the resistance value was obtained by calculation.

Change rate of resistance value before and after driving = | (resistance value after driving / resistance value before driving) −1 | × 100
A value closer to 0 indicates a smaller rate of change before and after driving.

Evaluation results are shown in Table 3. The change rate of the resistance value of each organic EL element is shown as a relative value when the change rate of the resistance value of the organic EL element 1-2 is 100.

(2) Chromaticity For each of the produced organic EL elements, the emission color was measured using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.), and the front luminance was measured twice, and the Y value was used as an index. It was.
Table 3 shows the measurement results.

(3) Rate of change in emission spectrum before and after driving organic EL element The emission spectrum before and after driving the organic EL element after driving for 1000 hours at room temperature (25 ° C.) under a constant current condition of ^2.5 mA / cm ² is CS−. 1000 (manufactured by Konica Minolta Co., Ltd.) was used, and the measurement result was calculated by the following formula to obtain the rate of change in chromaticity.

Rate of change in chromaticity before and after driving = | (Y value after driving / Y value before driving) −1 | × 100
A value closer to 0 indicates a smaller rate of change before and after driving.

Evaluation results are shown in Table 3. The rate of change in chromaticity of each organic EL element is shown as a relative value when the rate of change in chromaticity of the organic EL element 1-2 is 100.

(4) Summary As is apparent from Table 3, the organic EL elements 1-3 to 1-14 of the present invention have a resistance value of the light emitting layer and the organic EL elements 1-1 and 1-2 of the comparative example. It was shown that the rate of change in the half-value width of chromaticity was small, and an organic EL device in which the change in physical properties of the thin film of the light emitting layer was small could be obtained.
Further, the organic EL elements 1-1 and 1-2 of the comparative example have a high Y value and poor color purity, whereas the organic EL elements 1-3 to 1-14 of the present invention have excellent chromaticity. I understand that.

[Example 3]
<< Production of organic EL elements >>
(1) Fabrication of organic EL element 2-1 As an anode, patterning was performed on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm × 100 mm × 1.1 mm glass substrate was formed with ITO (indium tin oxide). Thereafter, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) diluted to 70% with pure water at 3000 rpm, A thin film was formed by spin coating under conditions of 30 seconds and then dried at 200 ° C. for 1 hour to provide a first hole transport layer having a layer thickness of 20 nm.

This substrate was transferred to a nitrogen atmosphere, and spin was performed at 2500 rpm for 30 seconds on a first hole transport layer using a solution of 50 mg of ADS254BE (American Dye Source, Inc.) dissolved in 10 ml of monochlorobenzene. A thin film was formed by a coating method. Furthermore, it vacuum-dried at 130 degreeC for 1 hour, and the 2nd positive hole transport layer was formed.

A thin film is formed on this second hole transport layer by spin coating using a solution of 100 mg of Comparative Compound A and 13 mg of dopant D-63 dissolved in 10 ml of butyl acetate at 1000 rpm for 30 seconds. did. Furthermore, it vacuum-dried at 60 degreeC for 1 hour, and was set as the light emitting layer with a layer thickness of about 45 nm.

Next, a thin film was formed on the light emitting layer by spin coating under a condition of 1000 rpm and 30 seconds using a solution of 50 mg of BCP dissolved in 10 ml of hexafluoroisopropanol (HFIP). Furthermore, it vacuum-dried at 60 degreeC for 1 hour, and was set as the electron carrying layer with a layer thickness of about 25 nm.

Subsequently, this substrate was fixed to a substrate holder of a vacuum evaporation apparatus, and after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, potassium fluoride was evaporated as an electron injection layer to a thickness of 0.4 nm, and aluminum was further added. A cathode was formed by vapor deposition at a thickness of 110 nm, and an organic EL element 2-1 was produced.

(2) Preparation of organic EL element 2-2 to 2-14 In the preparation of organic EL element 2-1, the same procedure was performed except that the dopant material and the host material were changed to the compounds shown in Table 4. 2-2 to 2-14 were produced.

<< Evaluation of organic EL elements >>
When evaluating each produced organic EL element, it was sealed in the same manner as the organic EL element 1-1 of Example 1, and an illumination device as shown in FIGS. 2 and 3 was formed and evaluated.
Each sample thus produced was evaluated for the rate of change in resistance value, chromaticity, and rate of change of the light emitting layer in the same manner as in Example 1.
The evaluation results are shown in Table 4. The resistance value and chromaticity change rate of each organic EL element are shown as relative values when the resistance value and chromaticity change rate of the organic EL element 2-2 are set to 100.

As is apparent from Table 4, the organic EL elements 2-3 to 2-14 of the present invention are half the resistance value and chromaticity of the light emitting layer compared to the organic EL elements 2-1 and 2-2 of the comparative example. It was shown that the rate of change of the value range was small, and an organic EL device having a small change in physical properties of the light emitting layer thin film could be obtained.
Furthermore, the organic EL elements 2-1 and 2-2 of the comparative example have high Y values and poor color purity, whereas the organic EL elements 2-3 to 2-14 of the present invention have excellent chromaticity. I understand that.

[Example 4]
<< Production of organic EL elements >>
(1) Fabrication of organic EL element 3-1 As an anode, patterning was performed on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a glass substrate of 100 mm × 100 mm × 1.1 mm. Thereafter, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, 200 mg of TPD is put into a molybdenum resistance heating boat, 200 mg of Comparative Compound A is put into another molybdenum resistance heating boat, and the other resistance heating boat made of molybdenum is put into another molybdenum resistance heating boat. Add 200 mg of compound D-73, put 200 mg of compound D-15 in another molybdenum resistance heating boat, put 200 mg of compound D-1 in another molybdenum resistance heating boat, and put BCP in another molybdenum resistance heating boat. 200 mg was placed and attached to a vacuum deposition apparatus.

The vacuum chamber is then depressurized to 4 × 10 ⁻⁴ Pa, heated by energizing a heating boat containing TPD, deposited on a transparent support substrate at a deposition rate of 0.1 nm / second, and transporting holes with a layer thickness of 10 nm. A layer was provided.

Further, the heating boat containing the comparative compound A as the host compound, the compound D-73 as the dopant, the compound D-15, and the compound D-1 was energized and heated, and the deposition rate was 0.1 nm / second, 0 Co-deposited on the hole transport layer at 0.025 nm / second, 0.0007 nm / second, and 0.0002 nm / second to provide a light emitting layer having a layer thickness of 60 nm.

Furthermore, the heating boat containing BCP was energized and heated, and was deposited on the light emitting layer at a deposition rate of 0.1 nm / second to provide an electron transport layer having a layer thickness of 20 nm.

Subsequently, potassium fluoride was vapor-deposited as an electron injection layer with a layer thickness of 0.5 nm, and aluminum was further vapor-deposited with a thickness of 110 nm to form a cathode, thereby producing an organic EL element 3-1.

(2) Preparation of organic EL elements 3-2 to 3-9 In the preparation of organic EL element 3-1, the same procedure was performed except that the dopant material and the host material were changed to the compounds shown in Table 5. 3-2 to 3-9 were produced.

When the produced organic EL elements were energized, almost white light was obtained, and it was found that they could be used as a lighting device. Moreover, even when it replaced with the other exemplary compound concerning this invention, it turned out that white light emission is obtained similarly.

<< Evaluation of organic EL elements >>
When evaluating each produced organic EL element, it was sealed in the same manner as the organic EL element 1-1 of Example 1, and an illumination device as shown in FIGS. 2 and 3 was formed and evaluated.

(1) Measurement of chromaticity For each of the produced organic EL elements, the luminance of the emitted light was measured using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.), and the front luminance at a viewing angle of 2 degrees was measured to be 1000 cd / It was confirmed that the chromaticity in the CIE 1931 color system at m ² was in the region of x = 0.33 ± 0.07, y = 0.33 ± 0.1, and was white light.

(2) Change rate of resistance value before and after organic EL element driving For each of the produced organic EL elements, the change rate of the resistance value of the light emitting layer was evaluated in the same manner as in Example 1.
The evaluation results are shown in Table 5. The change rate of the resistance value of each organic EL element is shown as a relative value when the change rate of the resistance value of the organic EL element 3-1 is 100.

(3) Summary As is apparent from Table 5, the organic EL elements 3-2 to 3-9 of the present invention have a smaller change rate of the resistance value of the light emitting layer than the organic EL element 3-1 of the comparative example. As a result, an organic EL device having a small change in physical properties of the thin film of the light emitting layer was obtained.

[Example 5]
≪Manufacture of organic EL full-color display device≫
Hereinafter, a manufacturing procedure of the organic EL full-color display device will be described with reference to FIGS. 9A to 9E.

First, after patterning at a pitch of 100 μm on a substrate (NH 45 manufactured by NH Techno Glass Co., Ltd.) on which an ITO transparent electrode 202 was formed as a positive electrode on a glass substrate 201 (see FIG. 9A), on this glass substrate 201 A non-photosensitive polyimide partition wall 203 (width 20 μm, thickness 2.0 μm) was formed between the ITO transparent electrodes 202 by photolithography (see FIG. 9B).

Next, a hole injection layer composition having the following composition is ejected and injected on the ITO electrode 202 between the partition walls 203 using an inkjet head (manufactured by Epson Corporation: MJ800C), and irradiated with ultraviolet light for 200 seconds. A hole injection layer 204 having a layer thickness of 40 nm was provided by drying at 60 ° C. for 10 minutes (see FIG. 9C).

A blue light-emitting layer composition, a green light-emitting layer composition, and a red light-emitting layer composition having the following compositions are similarly ejected and injected onto the hole injection layer 204 using an inkjet head, and dried at 60 ° C. for 10 minutes. The

light emitting layers

205B, 205G, and 205R for each color were provided (see FIG. 9D).

Next, an electron transport material is deposited so as to cover each of the

light emitting layers

205B, 205G, and 205R to provide an electron transport layer (not shown) having a thickness of 20 nm, and lithium fluoride is further deposited to form a layer having a thickness of 0.6 nm. An electron injection layer (not shown) was provided, Al was evaporated, and a cathode 206 having a thickness of 130 nm was provided to produce an organic EL element (see FIG. 9E).

(Hole injection layer composition)
HT-44 20 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass

(Blue light emitting layer composition)
Exemplified Compound H2-30 0.70 parts by mass Compound D-73 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (green light emitting layer composition)
Exemplified Compound H2-30 0.70 parts by mass Compound D-15 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass (red light emitting layer composition)
Illustrative Compound H2-30 0.70 parts by mass Compound D-1 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass

It was found that the produced organic EL full-color display device exhibited blue, green and red color by applying a voltage to each electrode, had high durability, and could be used as a clear full-color display device.

The present invention can be particularly suitably used to provide an organic EL element having a small change in resistance value of the light emitting layer over time, and a lighting device and a display device including the organic EL element.

101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen gas 109 Water trapping agent 201 Glass substrate 202 ITO transparent electrode 203 Partition wall 204

Hole injection layer

205B, 205G, 205R Light emitting layer 206 Cathode

Claims

An organic electroluminescence device in which an organic functional layer including a light emitting layer is sandwiched between an anode and a cathode,
At least one layer of the organic functional layer contains a compound having a chemical shift value in the range of 40 to 48 ppm in 31 P-NMR spectrum when dissolved together with triethylphosphine oxide in toluene. Organic electroluminescence device.
The compound having a chemical shift value in the range of 40 to 48 ppm in the 31 P-NMR spectrum has an excited triplet state (T 1 ) energy of 3.00 eV or more and a nitrogen content of 3.0 to 2. The organic electroluminescence device according to claim 1, wherein the content is in the range of 15.0%.
The light emitting layer contains a complex of iridium or platinum,
3. The organic electroluminescence device according to claim 1, wherein the complex has a nitrogen content of 10.0 to 30.0% and emits phosphorescence when energized.
The light emitting layer contains a fluorescent compound,
The organic electroluminescence device according to any one of claims 1 to 3, wherein an internal quantum efficiency in electrical excitation of the fluorescent compound is 50% or more.
5. The compound having a chemical shift value in the range of 40 to 48 ppm in the 31 P-NMR spectrum is a compound having a structure represented by the following general formula (1): The organic electroluminescent element as described in any one of the above.

(In general formula (1), ring α and ring β are each independently a pyrrole ring, furan ring, thiophene ring, imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole. Represents a ring, a tetrazole ring, an oxazole ring, an isoxazole ring, an oxadiazole ring, a thiazole ring, an isothiazole ring or a thiadiazole ring, and R is linked at an arbitrary position of ring α or ring β. And n represents an integer of 1 to 8.)
The organic electroluminescence device according to claim 5, wherein the compound having a structure represented by the general formula (1) is a compound having a structure represented by the following general formula (2).

(In general formula (2), ring α, ring β and R have the same meaning as ring α, ring β and R in general formula (1). M represents an integer of 1 to 6. L represents 2) Represents a valent linking group.)
The organic electroluminescence element according to any one of claims 1 to 6, wherein the organic electroluminescence element emits white light.
A lighting device comprising the organic electroluminescence element according to any one of claims 1 to 7.
A display device comprising the organic electroluminescence element according to any one of claims 1 to 7.