WO2021059813A1

WO2021059813A1 - Organic electroluminescent element

Info

Publication number: WO2021059813A1
Application number: PCT/JP2020/031573
Authority: WO
Inventors: 彰宏木村
Original assignee: コニカミノルタ株式会社
Priority date: 2019-09-27
Filing date: 2020-08-21
Publication date: 2021-04-01
Also published as: JPWO2021059813A1

Abstract

An organic electroluminescent element according to the present invention is provided with a substrate, an electrode 1, a functional layer, and an electrode 2 in this order, wherein: the functional layer is configured from a single layer or a plurality of layers; a layer, of the functional layer, that is in contact with the electrode 2 is formed of an organic film; an organic substance contained in the organic film is non-crosslinked; E, derived from formula (1) specified by the glass transition point and molecular weight of the organic substance, is 3,300 cal/mol or more; and the electrode 2 is of a coating film.　Formula (1): E=0.5×R×Tg×ln(M) [In the formula, R[cal/K･mol] represents the gas constant, Tg represents the glass transition point [K] of the organic substance, and M represents the molecular weight (the number average molecular weight when the organic substance is a polymer) of the organic substance.]

Description

Organic electroluminescence device

The present invention relates to an organic electroluminescence element, and more particularly to an organic electroluminescence element that does not cause an electric leakage abnormality even when an electrode is applied and formed on an organic film formed without using cross-linking.

When a coatable electrode used for an organic electroluminescence device (hereinafter, also referred to as an “organic EL device”) is formed on a functional layer (hereinafter, also referred to as an “electrode lower layer”), the electrode material is used. In order to fabricate the device, it was necessary that the mixed solution did not penetrate into the lower electrode layer, diffuse into the lower electrode layer during or after the film formation, or mechanically destroy the lower electrode layer. This is because if the electrode material gets into the lower layer of the electrode due to permeation, diffusion, or the like, a device failure due to electric leakage occurs (see Patent Documents 1 to 3).
In order to deal with this problem, the under-electrode layer has been dealt with by cross-linking an organic substance or forming a layer using an inorganic substance.

However, in order to form a layer using an inorganic substance, a method of coating and forming inorganic nanoparticles and a method of forming a film by firing a precursor (see Patent Document 4) are known, but both of them. It is known that minute gaps and cracks are generated in the membrane, and it is known that the permeation of the solvent easily occurs.

On the other hand, in the film crosslinked with an organic substance, unreacted crosslinked ends remain, resulting in a decrease in performance as an organic EL device.
The next possible countermeasure is to increase only the molecular weight by increasing the molecular weight of the material instead of cross-linking. However, another problem arises here. That is, in a coating type organic EL device, it is necessary to select "a solvent that dissolves the material of the upper layer without dissolving the lower layer" for each lamination (see Patent Document 5), and due to its characteristics, it is inevitably applied to the upper layer. Indeed, the selection range of the solvent becomes narrow.
Therefore, since the lower layer of the electrode is the uppermost layer of the functional layer of the organic EL element, there are few solvent choices, and further, when the solubility is lowered due to the increase in the molecular weight of the material, the selection range is originally small. The solvent choices will be further narrowed. Further, when the conjugated length is extended due to the increase in molecular weight, the absorption wavelength is lengthened. In an organic EL element, if the absorption wavelength of the material becomes long and a portion overlapping the emission wavelength appears, the luminous efficiency of the device is fatally reduced, and increasing the molecular weight of the material is not an easy means. Taking this into consideration, I tentatively ignored these problems and tried to verify the principle only from the viewpoint of "whether an electric leakage abnormality occurs due to the increase in the molecular weight of the material". It was not a countermeasure, and an electric leakage failure occurred.

Japanese Unexamined Patent Publication No. 2001-185363 Japanese Unexamined Patent Publication No. 2003-91246 Japanese Unexamined Patent Publication No. 2010-33972 Japanese Unexamined Patent Publication No. 2011-150803 Japanese Unexamined Patent Publication No. 2009-63850

The present invention has been made in view of the above problems and situations, and the problem to be solved is an organic electroluminescence that does not cause an electric leakage abnormality even if an electrode is applied and formed on an organic film formed without using cross-linking. It is to provide a luminescent element.

In the process of examining the cause of the above problem in order to solve the above-mentioned problems, the present inventor constitutes the organic film of the layer in contact with the electrode 2 among the functional layers with a non-crosslinking organic substance, and forms the organic film on the organic film. We have clarified the requirements for an organic film that does not cause abnormalities even when a film of coatable electrodes is formed. That is, as shown in the following formula (1), an organic film is formed by forming an organic film using an organic substance having an E of 3300 cal / mol or more, which is represented by not only the molecular weight but also the two parameters of the glass transition point. We have found that even if an electrode that can be applied is formed on the organic film, an electric leakage abnormality does not occur, and the present invention has been made.
That is, the above problem according to the present invention is solved by the following means.

1. 1. An organic electroluminescence device including a base material, an electrode 1, a functional layer, and an electrode 2 in this order.
The functional layer is composed of a single layer or a plurality of layers.
Of the functional layers, the layer in contact with the electrode 2 is made of an organic film, and the organic substances contained in the organic film are not crosslinked.
E derived from the following formula (1) defined by the glass transition point and molecular weight of the organic substance is 3300 cal / mol or more, and
An organic electroluminescence device in which the electrode 2 is a coating film.
Equation (1): E = 0.5 × R × Tg × ln (M)
[In the formula, R [cal / K · mol] represents the gas constant, Tg represents the glass transition point [K] of the organic substance, and M represents the molecular weight of the organic substance (when the organic substance is a polymer, the number average molecular weight). ]

2. The organic electroluminescence device according to item 1, wherein in the formula (1), the E is 4000 cal / mol or more.

3. The organic electroluminescence device according to item 1 or 2, wherein the glass transition point (Tg) of the organic substance in the formula (1) is 470 K or more.

4. The organic electroluminescence device according to any one of items 1 to 3, wherein the organic substance has a molecular weight (M) of 40,000 or more in the formula (1).

5. The organic electroluminescence device according to item 4, wherein in the formula (1), the molecular weight (M) of the organic substance is 90,000 or more.

According to the above means of the present invention, it is possible to provide an organic electroluminescence element that does not cause an electric leakage abnormality even when an electrode is applied and formed on an organic film formed without using cross-linking.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.
The mechanical strength of the lower layer of the electrode is the most important mechanism for avoiding the occurrence of abnormalities in electrode formation by coating on an organic film containing an organic substance having an E of 3300 cal / mol or more in the above formula (1) of the present invention. It is inferred that it will be.
The formula (1) according to the present invention is a formula relating to the molar cohesive force obtained with reference to the non-patent document 1, and is a parameter related to the intermolecular interaction in the membrane. The metal or inorganic material used as the electrode material is harder than the organic material under the electrode, and when the coating film of the electrode is formed, the underlayer of the electrode is mechanically destroyed by the influence of flow or convection.
Therefore, the larger the E represented by the above formula (1) defined by the glass transition point and the molecular weight, which is the parameter of the intermolecular interaction, the higher the mechanical strength of the lower layer of the electrode can be increased, and the mechanical strength of the lower electrode layer can be increased, and the mechanical strength of the electrode lower layer can be increased. Does not cause anomalies. In the above formula (1), since E is expressed by the product of the glass transition point and the molecular weight, E may not be sufficient simply by increasing the molecular weight. It is predicted that the glass transition point was insufficient because the simple high molecular weight increase that the present inventor verified in advance did not take measures against the leakage abnormality. Therefore, increasing both the molecular weight and the glass transition point is the key in the present invention, and by forming an organic film containing an organic substance in which E in the above formula (1) is 3300 cal / mol or more, the present invention is used. It is presumed that the effect will be obtained.

Schematic diagram showing an example of a method for manufacturing an organic EL element using an inkjet printing method. Schematic external view showing an example of the structure of an inkjet head applicable to an inkjet printing method. Schematic external view showing an example of the structure of an inkjet head applicable to an inkjet printing method. Schematic diagram of lighting equipment Schematic diagram of lighting equipment

The organic electroluminescence element of the present invention is an organic electroluminescence element provided with a base material, an electrode 1, a functional layer and an electrode 2 in this order, wherein the functional layer is composed of a single layer or a plurality of layers, and the function is described. Of the layers, the layer in contact with the electrode 2 is made of an organic film, and the organic substance contained in the organic film is not crosslinked, and is derived from the following formula (1) defined by the glass transition point and the molecular weight of the organic substance. E is 3300 cal / mol or more, and the electrode 2 is a coating film.
Equation (1): E = 0.5 × R × Tg × ln (M)
[In the formula, R [cal / K · mol] represents the gas constant, Tg represents the glass transition point [K] of the organic substance, and M represents the molecular weight of the organic substance (when the organic substance is a polymer, the number average molecular weight). ]
This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, in the above formula (1), it is preferable that the E is 4000 cal / mol or more because the leakage abnormality can be further suppressed.

Further, in the above formula (1), it is preferable that the glass transition point (Tg) of the organic substance is 470K or more.

Further, in the formula (1), the molecular weight (M) of the organic substance is preferably 40,000 or more, and particularly preferably 90,000 or more.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described. In the present application, "-" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

[Overview of the Organic Electroluminescence Device of the Present Invention]
The organic electroluminescence element of the present invention is an organic electroluminescence element provided with a base material, an electrode 1, a functional layer and an electrode 2 in this order, wherein the functional layer is composed of a single layer or a plurality of layers, and the function is described. Of the layers, the layer in contact with the electrode 2 is made of an organic film, and the organic substance contained in the organic film is not crosslinked, and is derived from the formula (1) defined by the glass transition point and the molecular weight of the organic substance. E is 3300 cal / mol (13807 J / mol = 13.81 kJ / mol) or more, and the electrode 2 is a coating film.
Equation (1): E = 0.5 × R × Tg × ln (M)
[In the formula, R [cal / K · mol] represents the gas constant, Tg represents the glass transition point [K] of the organic substance, and M represents the molecular weight of the organic substance (when the organic substance is a polymer, the number average molecular weight). ]

The glass transition point (transition temperature) was measured by a DSC device (differential scanning calorimetry device), and was determined by, for example, RDC220 (manufactured by Seiko Instruments Inc.) under a temperature rising condition of 10 ° C./min. The temperature.
The number average molecular weight when the organic substance is a polymer can be obtained from the molecular weight distribution measured by gel permeation chromatography (GPC). Specifically, first, the measurement sample was added to tetrahydrofuran so as to have a concentration of 1 mg / mL, dispersed at room temperature for 5 minutes using an ultrasonic disperser, and then treated with a membrane filter having a pore size of 0.2 μm. To prepare the sample solution. For example, using a GPC apparatus HLC-8120GPC (manufactured by Tosoh Corporation) and a column (“TSKgel guard culture SuperHZ-L” and “TSKgel SuperHZM-M” (manufactured by Tosoh Corporation)) while maintaining the column temperature at 40 ° C., a carrier solvent. Tetrahydrofuran is flowed at a flow rate of 0.2 mL / min. 10 μL of the prepared sample solution was injected into the GPC device together with the carrier solvent, the sample was detected using a refractive index detector (RI detector), and the calibration line measured using monodisperse polystyrene standard particles was used. , Calculate the molecular weight distribution of the sample. The calibration curves have molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , and 5. 10 points of polystyrene standard particles (manufactured by Pressure Chemical) of 1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ^6. ) Is measured.

The glass transition point (Tg) of the organic substance is preferably 470 K or more from the viewpoint of improving the mechanical strength of the lower electrode layer.
The molecular weight (M) of the organic substance is preferably 40,000 or more from the viewpoint of improving the mechanical strength of the lower layer of the electrode, and particularly preferably 90,000 or more.

In the organic film using an organic substance having E of 3300 cal / mol or more in the formula (1) of the present invention, the organic film may be a film of a mixture of two or more kinds. In that case, an organic substance having an abundance ratio of 29% or more in the membrane and the smallest E value is adopted. For example, as an extreme example, assuming a film containing 99% of a material having an E of more than 3300 cal / mol and 1% of a material having an E of less than 3300 cal / mol, 1% of the material is destructively affected during electrode formation. However, since 99% of the strong material is present in the entire film, abnormalities such as electric leakage do not occur. The above-mentioned abundance ratio in the membrane of 29% or more indicates the minimum amount required to break the membrane, and the value of E of the material is 3300 cal / mol or more. It is a condition that satisfies the requirements of the invention. However, from the viewpoint of leakage abnormality, it is desirable that E of all the materials constituting the film is 3300 cal / mol or more.

In the present invention, "the organic matter contained in the organic film is not crosslinked" means that the organic matter (organic compound) components constituting the organic film are not crosslinked by the crosslinking reaction. However, even if a compound having a crosslinkable group is contained as a component constituting the organic film, if the content does not impair the effect of the present invention, for example, the content is less than 23% by mass, It is considered that there is no cross-linking between organic substances.
Here, "crosslinking" refers to a reaction process in which a plurality of molecules are linked so as to bridge each other by a chemical covalent bond.
Further, although the content of the compound having a crosslinkable group is less than 23% by mass, the introduction of the compound having a crosslinkable group lowers the performance as an organic EL element, so that the compound has a crosslinkable group. The content of the compound is preferably 0% by mass.
In the present invention, the layer (organic film) in contact with the electrode has a content that does not impair the effect of the present invention, and for example, when the content is less than 20% by mass, an inorganic compound may be contained. ..

E in the formula (1) of the present invention is more preferably 4000 cal / mol (16736 J / mol = 16.74 kJ / mol) or more, and in principle, the larger the value, the better, but in the organic film. Because it is determined from the glass transition point and molecular weight of the organic matter (also referred to as "organic material under the electrode"), 7000 cal / mol (29288J /) due to the high molecular weight of the π-conjugated material and the improvement limit of the glass transition point. mol = 29.29 kJ / mol) is the theoretical limit value.

Specific examples of the organic substance having E of 3300 cal / mol or more in the above formula (1) include the compounds shown below, but the present invention is not limited thereto.

Hereinafter, the organic electroluminescence device of the present invention will be described in detail.

[Structure of organic EL element]
Typical element configurations of the organic EL device of the present invention include, but are not limited to, the following configurations.
(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) Electron / hole injection layer / hole transport layer / (electron blocking layer /) light emitting layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode Among the above, the configuration of (vii) is preferable. Used, but not limited to.

In the organic EL device having the above-described device configuration, the electrode 2 according to the present invention may be an anode or a cathode, but a cathode is preferable from the viewpoint of exhibiting the effect of the present invention.
When the electrode 2 is a cathode, the electrode 1 is an anode, and when the electrode 2 is an anode, the electrode 1 is a cathode.
In particular, in the present invention, it is preferable that the electrode 2 is a cathode and the layer in contact with the cathode (under the electrode) is a light emitting layer, an electron transport layer, or an electron injection layer.

The light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers. If necessary, a hole blocking layer (also referred to as a hole barrier 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, and the light emitting layer and the electrode may be provided. 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 between the two.
The electron transport layer according to the present invention 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, it may be composed of a plurality of layers.
The hole transport layer according to the present invention 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. Further, it may be composed of a plurality of layers.
In the above typical device configuration, the layer excluding the anode and the cathode is also referred to as a "functional layer (or organic functional layer)".

(Tandem structure)
The organic EL device of the present invention may be a device having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are laminated.
As a typical element configuration of the tandem structure, for example, the following configuration can be mentioned.
Anode / 1st light emitting unit / 2nd light emitting unit / 3rd light emitting unit / cathode Anode / 1st light emitting unit / intermediate layer / 2nd light emitting unit / intermediate layer / 3rd 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.
Further, the third light emitting unit may not be provided, while a light emitting unit or an intermediate layer may be further provided between the third light emitting unit and the electrode.

The plurality of light emitting units may be directly laminated or may be laminated via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, or an intermediate layer. A known material and structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the adjacent layer on the anode side and holes to the adjacent layer on the cathode side.

Examples of the material used for the intermediate layer include ITO (inorganic tin oxide), IZO ( _{inorganic zinc oxide), ZnO 2} , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, and CuAlO _2. , CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ , Al and other conductive inorganic compound layers, Au / Bi ₂ O _{3 and} other bilayer films, SnO ₂ / Ag / SnO ₂ , ZnO / Ag / Multilayer films such as 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} , and conductive organic substances such as oligothiophene. , Metallic phthalocyanines, metal-free phthalocyanines, metal porphyrins, conductive organic compound layers such as metal-free porphyrins, etc., but the present invention is not limited thereto.

Preferred configurations in the light emitting unit include, for example, configurations in which the anode and the cathode are removed from the configurations (i) to (vii) mentioned in the above typical element configurations, but the present invention is limited thereto. Not done.

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, US Pat. No. 6,337,492, International. Publication No. 2005/09087, Japanese Patent Application Laid-Open No. 2006-228712, Japanese Patent Application Laid-Open No. 2006-24791, Japanese Patent Application Laid-Open No. 2006-49393, Japanese Patent Application Laid-Open No. 2006-49394, Japanese Patent Application Laid-Open No. 2006-49396, Japanese Patent Application Laid-Open No. 2011 -96679, Japanese Patent Application Laid-Open No. 2005-340187, Japanese Patent No. 4711424, Japanese Patent No. 3496681, Japanese Patent No. 3884564, Japanese Patent No. 421369, Japanese Patent Application Laid-Open No. 2010-192719, Japanese Patent Application Laid-Open No. 2009-07629, The element configurations and constituent materials described in Japanese Patent Application Laid-Open No. 2008-0784414, Japanese Patent Application Laid-Open No. 2007-059848, Japanese Patent Application Laid-Open No. 2003-272860, Japanese Patent Application Laid-Open No. 2003-045676, International Publication No. 2005/094130, etc. are listed. However, the present invention is not limited thereto.

Hereinafter, each layer constituting the organic EL device of the present invention will be described.
《Light emitting layer》
The light emitting layer according to the present invention is a layer that provides a place where electrons and holes injected from an electrode or an adjacent layer are recombined and emit light via excitons, and the light emitting portion is a layer of the light emitting layer. It may be inside or at the interface between the light emitting layer and the adjacent layer.
The total thickness of the light emitting layer is not particularly limited, but the homogeneity of the formed layer, prevention of applying an unnecessary high voltage at the time of light emission, and improvement of the stability of the light emitting color with respect to the driving current are improved. From the viewpoint, it is preferably adjusted within the range of 2 nm to 5 μm, more preferably adjusted within the range of 2 to 500 nm, and further preferably adjusted within the range of 5 to 200 nm.
The thickness of each light emitting layer 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 adjusted within the range of 3 to 150 nm. ..

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).
Further, in the present invention, when the light emitting layer is a layer in contact with the electrode 2 (for example, a cathode or an anode), the organic substance having an E derived from the above formula (1) of 3300 cal / mol or more is applied to the light emitting layer. contains.

(1) Light-emitting dopant Examples of the light-emitting dopant include a fluorescent dopant (also referred to as a fluorescent dopant or a fluorescent compound), a delayed fluorescent dopant, or a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound). Is preferably used.
In the present invention, the light emitting layer preferably contains the light emitting dopant in the range of 5 to 100% by mass, and more preferably in the range of 10 to 30% by mass.
The concentration of the light emitting dopant in the light emitting layer can be arbitrarily determined based on the specific light emitting dopant used and the requirements of the device, and is contained at a uniform concentration with respect to the layer thickness direction of the light emitting layer. It may have an arbitrary concentration distribution.
Further, a plurality of types of light emitting dopants may be used in combination, and a combination of light emitting dopants having different structures, a π-conjugated compound of the present invention, or a combination of a fluorescent light emitting compound and a phosphorescent light emitting compound may be used. You may use it. Thereby, an arbitrary emission color can be obtained.

The color emitted by the organic EL element according to the present invention is shown in FIG. 4.16 on page 108 of the "New Color Science Handbook" (edited by the Japan Color Society, edited by the University of Tokyo Press, 1985). It is determined by the color when the result measured 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 light emitting colors and exhibits white light emission.
The combination of light emitting dopants showing white color is not particularly limited, and examples thereof include a combination of blue and orange, a combination of blue and green and red, and the like.
The white color in the organic EL element according to the present invention is not particularly limited and may be white color closer to orange or white color closer to blue, but when the 2 degree viewing angle front luminance is measured by the above method. In addition, it is preferable that the chromaticity in the CIE 1931 color system at 1000 cd / m2 is within the region of x = 0.39 ± 0.09 and y = 0.38 ± 0.08.

(1.1) Phosphorescent Dopant A phosphorescent dopant according to the present invention (hereinafter, also referred to as “phosphorescent dopant”) 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, a compound that emits phosphorescent light at room temperature (25 ° C.), and has a phosphorescent quantum yield of 25. It is defined as a compound of 0.01 or more at ° C, but a preferable phosphorescence quantum yield is 0.1 or more.

The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescence dopant according to the present invention can achieve the above phosphorescence quantum yield (0.01 or more) in any of any solvents. Just do it.

As the phosphorescent dopant that can be used in the present invention, it can be appropriately selected from known ones used for the light emitting layer of the organic EL element.
Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
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, Country (24) JP 2018-70551 A 2018.5.10 10 20
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Among them, preferred phosphorescent dopants include organometallic complexes having Ir as the 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.
The luminescent compound contained in the light emitting layer is preferably a fluorescent compound, more preferably a delayed fluorescent compound. It is also preferable that the luminescent compound contained in the light emitting layer is a phosphorescent compound.

(1.2) Fluorescent Luminescent Dopant A fluorescent luminescent dopant according to the present invention (hereinafter, also referred to as “fluorescent dopant”) will be described.
The fluorescent dopant according to the present invention is a compound capable of emitting light from the excited singlet, and is not particularly limited as long as light emission from the excited singlet is observed.
The fluorescent dopant according to the present invention may be appropriately selected from known fluorescent dopants and delayed fluorescent dopants used in the light emitting layer of the organic EL device.

Examples of fluorescent dopants that can be used in the present invention include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluorantene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylallylen derivatives, styrylamine derivatives, arylamine derivatives, and boron complexes. Examples thereof include coumarin derivatives, pyran derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, and rare earth complex compounds. Further, in recent years, light emitting dopants using delayed fluorescence have also been developed, and these may be used.
Specific examples of the light emitting dopant using delayed fluorescence include the compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2010-11-213643, Japanese Patent Application Laid-Open No. 2010-93181, and Japanese Patent No. 5366106. However, the present invention is not limited thereto.

(2) Host Compound The host compound according to the present invention is a compound mainly responsible for injection and transport of electric charges in the light emitting layer, and its own light emission is not substantially observed in the organic EL element.
A compound having a phosphorescent quantum yield of less than 0.1 at room temperature (25 ° C.) is preferable, and a compound having a phosphorescent quantum yield of less than 0.01 is more preferable. Further, among the compounds contained in the light emitting layer, the mass ratio in the layer is preferably 20% or more.
Further, 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.

The host compound may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of electric charges, and it is possible to improve the efficiency of the organic EL device.

As a host compound, it has hole-transporting ability or electron-transporting ability, prevents the wavelength of light emission from being lengthened, and operates stably against heat generation when the organic EL element is driven at a high temperature or while the element is being driven. It is preferable to have a high glass transition temperature (Tg) from the viewpoint of allowing the particles to grow. Tg is preferably 90 ° C. or higher, and 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 in the present invention include, but are not limited to, the compounds described in the following documents.
JP 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357977, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002. 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003 -3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002- 302516, 2002-305083, 2002-305084, 2002-308837, US Patent Application Publication No. 2003/0175553, US Patent Application Publication No. 2006/0280965, USA 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, International 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. 2007/0637996, 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. 2012/0293947 , Japanese Patent Application Laid-Open No. 2008-074939, Japanese Patent Application Laid-Open No. 2007-254297, European Patent No. 2034538, International Publication No. 2011/055933, International Publication No. 2012/035853, Japanese Patent Application Laid-Open No. 2015-38941, etc. Ah To. Examples of host compounds described in JP-A-2015-38941 include compounds H-1 to H-230 described in [0255] to [0293] of the specification.

《Electron transport layer》
In the present invention, the electron transport layer may be 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 film thickness of the electron transport layer in the present invention is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably in the range of 2 to 500 nm, and further preferably in the range of 5 to 200 nm. Is.

The material used for the electron transport layer (hereinafter referred to as an electron transport material) may have any of electron injection property, transport property, and hole barrier property, and is available from among conventionally known compounds. Any one can be selected and used.
The electron transport material contained in the electron transport layer may be one kind or two or more kinds. For example, the electron transport layer may further contain the following conventionally known electron transport materials.

Conventionally known electron transporting materials include, for example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring substituted with nitrogen atoms), pyridine derivatives, and the like. Pyrimidine derivative, pyrazine derivative, pyridazine derivative, triazine derivative, quinoline derivative, quinoxalin derivative, phenanthroline derivative, azatriphenylene derivative, oxazole derivative, thiazole derivative, oxaziazole derivative, thiazazole derivative, triazole derivative, benzimidazole derivative, benzoxazole derivative, Benzthiazole derivatives, etc.), dibenzofuran derivatives, dibenzothiophene derivatives, silol derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene derivatives, etc.) and the like.
Further, metal complexes having a quinolinol skeleton or a dibenzoquinolinol skeleton as ligands, for example, 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 metal complexes thereof. A metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga or Pb can also be used as an electron transport material.
In addition, metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like can also be preferably used as an electron transport material. Further, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si or n-type-SiC is used like the hole injection layer and the hole transport layer. 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, the electron transport layer may be doped with a doping material as a guest material to form a highly n-type (electron-rich) electron transport layer. 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, JP-A-2001-102175, J. Mol. Apple. Phys. , 95, 5773 (2004) and the like.

Specific examples of the electron transport material used in the organic EL device of the present invention include, but are not limited to, the compounds described in the following documents.
US Patent No. 6528187, US Patent No. 7230107, US Patent Application Publication No. 2005/0025993, US Patent Application Publication No. 2004/0036077, US Patent Application Publication No. 2009/0115316. , US Patent Application Publication No. 2009/0101870, US 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), US Patent No. 7964293, US 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. 2007/0865552, International Publication No. 2008/114690, International Publication No. 2009/0694242, International Publication No. 2009/066797, International Publication No. 2009/054253, International Publication No. 2011/086935, International Publication No. 2010/150593, International Publication No. 2010/047707, European Patent No. 2311826, Japanese Patent Application Laid-Open No. 2010-251675, Japanese Patent Application Laid-Open No. 2009-209133, Japanese Patent Application Laid-Open No. 2009-209133. -124114, Japanese Patent Application Laid-Open No. 2008-277810, Japanese Patent Application Laid-Open No. 2006-156445, Japanese Patent Application Laid-Open No. 2005-340122, Japanese Patent Application Laid-Open No. 2003-45662, Japanese Patent Application Laid-Open No. 2003-31367, Japanese Patent Application Laid-Open No. 2003-282270 No., International Publication No. 2012/11034, etc.
The electron transport material may be used alone or in combination of two or more.
Further, in the present invention, when the electron transport layer is a layer in contact with the electrode 2 (for example, a cathode), the organic substance having an E derived from the formula (1) of 3300 cal / mol or more is applied to the electron transport layer. contains.

《Hole blocking layer》
The hole blocking layer is a layer having a function of an electron transporting 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, and holes while transporting electrons. It is possible to improve the recombination probability of electrons and holes by blocking the above.
In addition, the structure of the electron transport layer described above can be used as the hole blocking layer according to the present invention, if necessary.
The hole blocking layer is preferably provided adjacent to the cathode side of the light emitting layer.
The film thickness of the hole blocking layer is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.
As the material used for the hole blocking layer, the material used as the above-mentioned host compound is also preferably used for the hole blocking layer.

《Electron injection layer》
The electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness. It is described in detail in Volume 2, Chapter 2, "Electrode Materials" (pages 123-166) of "Forefront of Industrialization (published by NTS Co., Ltd. on November 30, 1998)".
In the present invention, the electron injection layer may be provided as needed 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 film thickness is preferably in the range of 0.1 to 5 nm, although it depends on the material. Further, it may be a non-uniform film in which the constituent material is intermittently present.

The details of the electron-injected layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specific examples of materials preferably used for the electron-injected layer include , Metals such as strontium and aluminum, alkali metal compounds such as lithium fluoride, sodium fluoride and potassium fluoride, alkaline earth metal compounds such as magnesium fluoride and calcium fluoride, oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq) and the like. It is also possible to use the above-mentioned electron transport material.
Further, the material used for the above-mentioned electron injection layer may be used alone or in combination of two or more.
Further, in the present invention, when the electron injection layer is a layer in contact with the electrode 2 (for example, a cathode), the organic substance having an E derived from the formula (1) of 3300 cal / mol or more is applied to the electron injection layer. contains.

《Hole transport layer》
In the present invention, the hole transport layer may be 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 film thickness of the hole transport layer is not particularly limited, but is usually in the range of 5 nm to 5 μm, more preferably in the range of 2 to 500 nm, and further preferably in the range of 5 to 200 nm. is there.

The material used for the hole transport layer (hereinafter referred to as the hole transport material) may have any of hole injection property, transport property, and electron barrier property, and is among conventionally known compounds. Any one can be selected and used from.
For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stillben derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives. , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polymer materials or oligomers in which polyvinylcarbazole and aromatic amines are introduced into the main chain or side chains, polysilane, conductivity. Sex polymers or oligomers (eg, PEDOT: PSS, aniline-based copolymers, polyaniline, polythiophene, etc.) and the like can be mentioned.

Examples of the triarylamine derivative include a benzidine type represented by α-NPD (4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl) and a starburst type represented by MTDATA. Examples thereof include compounds having fluorene or anthracene in the triarylamine linking core portion.
Hexaazatriphenylene derivatives as described in JP-A-2003-591432 and JP-A-2006-135145 can also be used as the hole transport material in the same manner.
Further, 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. Apple. Phys. , 95, 5773 (2004) and the like.
In addition, Japanese Patent Application Laid-Open No. 11-251067, J. Am. Hung et. al. So-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC as described in the authored literature (Applied Physics Letters 80 (2002), p.139) can also be used. Further, an orthometalated organometallic complex having Ir or Pt in the central metal as represented by Ir (ppy) _{3 is also preferably used.}
As the hole transporting material, the above-mentioned materials can be used, but a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organic metal complex, and an aromatic amine are introduced into the main chain or side chain. High molecular weight materials or oligomers are preferably used.

Specific examples of known and preferable hole transporting materials used in the organic EL device according to the present invention include the compounds described in the following documents in addition to the above-mentioned documents, and the present invention includes these. Not limited.
For example, Appl. Phys. Lett. 69, 2160 (1996), J. Mol. Lumin. 72-74, 985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007),
Apple. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997)
, Synth. Met. 111,421 (2000), SID SymposiumDigest, 37, 923 (2006), J. Mol. Mater. Chem. 3, 31
9 (1993), Adv. Mater. 6, 677 (1994), Chem. Mater. 15,3148 (2003), U.S. Patent Publication No. 2003/0162053, U.S. Patent Publication No. 2002/0158242, U.S. Patent Publication No. 2006/0240279, U.S. Patent Publication No. 2008/0220265, U.S. Patent No. 5061569, International Publication No. 2007/002683, International Publication No. 2009/01809, EP650955, US Patent Publication No. 2008/01245772, US Patent Publication No. 2007/0278938, US Patent Publication No. 2008/0106190, US Patent Publication No. 2008 / 0018221, International Publication No. 2012/115344, Japanese Patent Application Laid-Open No. 2003-591432, Japanese Patent Application Laid-Open No. 2006-135145, US Patent Application No. 13/585981, and the like.
The hole transporting material may be used alone or in combination of two or more.
Further, in the present invention, when the hole transport layer is a layer in contact with the electrode 2 (for example, the anode), the E derived from the formula (1) is 3300 cal / mol or more in the hole transport layer. Contains organic matter.

《Electronic blocking layer》
The electron blocking layer is a layer having a function of a hole transporting 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, and is composed of a material having a small ability to transport electrons while transporting holes. It is possible to improve the recombination probability of electrons and holes by blocking the above.
Further, the structure of the hole transport layer described above can be used as an electron blocking layer according to the present invention, if necessary.
The electron blocking layer is preferably provided adjacent to the anode side of the light emitting layer.
The thickness of the electron blocking layer is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.
As the material used for the electron blocking layer, the material used for the hole transporting layer described above is preferably used, and the material used as the host compound described above is also preferably used for the electron blocking layer.

《Hole injection layer》
The hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness, and is an “organic EL element”. And its industrialization forefront (published by NTS on November 30, 1998), Volume 2, Chapter 2, "Electrode Materials" (pages 123-166).
In the present invention, the hole injection layer may be provided as needed 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 also described in JP-A-9-45479, 9-2660062, 8-288609, etc., and examples of the material used for the hole injection layer include. , Materials used for the hole transport layer mentioned above and the like.
Among them, phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives as described in JP-A-2003-591432 and JP-A-2006-135145, metal oxides typified by vanadium oxide, amorphous carbon. , Polyaniline (emeraldine), polythiophene and other conductive polymers, tris (2-phenylpyridine) iridium complexes and the like, orthometallated complexes, triarylamine derivatives and the like are preferable.
The material used for the hole injection layer described above may be used alone or in combination of two or more.
Further, in the present invention, when the hole injection layer is a layer in contact with the electrode 2 (for example, the anode), the E derived from the formula (1) is 3300 cal / mol or more in the hole injection layer. Contains organic matter.

<< Other additives >>
The functional layer in the present invention described above may further contain other additives.
Examples of the additive include halogen elements such as bromine, iodine and chlorine, halogenated compounds, alkali metals and alkaline earth metals such as Pd, Ca and Na, compounds and complexes of transition metals, salts and the like.
The content of the additive can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 50 ppm or less, based on 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 and the purpose of favoring the energy transfer of excitons.

<< Method of forming functional layer >>
A method for forming a functional layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) in the present invention will be described.
The method for forming the functional layer in the present invention is not particularly limited, and a conventionally known method for forming a functional layer, for example, a vacuum vapor deposition method, a wet method (also referred to as a wet process), or the like can be used.
The wet method includes a spin coating method, a casting method, an inkjet printing method, a printing method, a die coating method, a blade coating method, a roll coating method, a spray coating method, a curtain coating method, an LB method (Langmuir-Brojet method), and the like. However, a method having high suitability for the roll-to-roll method such as a die coating method, a roll coating method, an inkjet printing method, and a spray coating method is preferable from the viewpoint of easy to obtain a homogeneous thin film and high productivity.

Examples of the liquid medium for dissolving or dispersing the organic material (including the organic substance according to the present invention) used for the functional layer include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, and halogens such as dichlorobenzene. Hydrocarbons, aromatic hydrocarbons such as toluene, xylene, mesityrene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.
Further, as a dispersion method, dispersion can be performed by a dispersion method such as ultrasonic waves, high shear force dispersion, or media dispersion.

Further, a different film forming method may be applied to each layer. When a thin-film deposition method is used 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 ^10-6 to ^10-2 Pa, and the vapor deposition rate is 0.01 to. It is desirable to appropriately select in the range of 50 nm / sec, substrate temperature -50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.
The functional layer in the present invention is preferably formed from the hole injection layer to the cathode by one vacuuming, but it may be taken out in the middle and a different film forming method may be applied. In that case, it is preferable to carry out the work in a dry inert gas atmosphere.

"anode"
As the anode in the organic EL element, a metal having a large work function (4 eV or more, preferably 4.5 V or more), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is preferably used. Specific examples of such an electrode material include metals such as Au and conductive transparent materials such as _{CuI, indium zinc oxide (ITO), SnO 2, and ZnO.} Further, a material such as IDIXO (In ₂ O _3- ZnO) which is amorphous and can produce a transparent conductive film may be used.

For the anode, a thin film may be formed by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much (about 100 μm or more). , The pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material.
Alternatively, when a coatable substance such as an organic conductive compound is used, a wet film forming method such as a printing method or a coating method can also be used. When emitting light from this anode, it is desirable to increase the transmittance to more than 10%, and the sheet resistance as the anode is several hundred Ω / sq. The following is preferable.
The film thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

"cathode"
As the cathode, a metal having a small work function (6 eV or less) (referred to as an electron-injectable metal), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, silver, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al). ₂ O ₃ ) Examples include mixtures, indium, lithium / aluminum mixtures, aluminum, and rare earth metals.
Among these, from the viewpoint of electron injectability and durability against oxidation and the like, a mixture of an electron injectable metal and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture. Magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, lithium / aluminum mixture, aluminum and the like are suitable.

The cathode can be used by using these electrode substances as a coatable substance such as metal nanoparticles, and can be formed by a wet film forming method such as a printing method or a coating method. Sheet resistance as a cathode is several hundred Ω / sq. The following is preferable, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.
Since the emitted light is transmitted, it is convenient that the emission brightness is improved if either the anode or the cathode of the organic EL element is transparent or translucent.
Further, a transparent or translucent cathode can be produced by producing the above metal on the cathode having a thickness of 1 to 20 nm and then producing the conductive transparent material mentioned in the description of the anode on the cathode. By applying the above, it is possible to manufacture an element in which both the anode and the cathode are transparent.

《Support board》
The type of support substrate (hereinafter, also referred to as a substrate, substrate, substrate, support, etc.) that can be used for the organic EL element in the present invention is not particularly limited, and is transparent. It may be opaque. When light is taken out 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 imparting flexibility to the organic EL element.

Examples of the resin film 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 acetate phthalate, cellulose esters such as 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, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, Arton (registered trademark) (manufactured by JSR) Alternatively, a cycloolefin resin such as Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be mentioned.

A film of an inorganic substance, an organic substance, or a hybrid film of both of them may be formed on the surface of the resin film, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. oxygen relative humidity (90 ± 2)% RH) is preferably a barrier film of 0.01g / (m ² · 24h) or less, still more, as measured by the method based on JIS K 7126-1987 the ^{^{permeability, 10 -3 mL / (m 2}} · 24h · atm) or less, the water vapor permeability is preferably a high barrier film of 10-5g / (m ² · 24h) or less.

The material for forming the gas barrier film may be any material having a function of suppressing infiltration of a material that causes deterioration of the element such as moisture and oxygen, and for example, silicon oxide, silicon dioxide, silicon nitride and the like can be used. Further, 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 an organic material. The stacking order of the inorganic layer and the organic layer is not particularly limited, but it is preferable to stack the inorganic layer and the organic layer alternately a plurality of times.

The method for forming the gas barrier film is not particularly limited, and for example, 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. Although legal, plasma CVD method, laser CVD method, thermal CVD method, coating method and the like can be used, the atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include a metal plate such as aluminum and stainless steel, a film or opaque resin substrate, and a ceramic substrate.
The external extraction quantum efficiency of the light emission of the organic EL device according to the present invention at room temperature is preferably 1% or more, more preferably 5% or more.
Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons passed through the organic EL element × 100.
Further, a hue improving filter such as a color filter may be used in combination, or a color conversion filter that converts the color emitted from the organic EL element into multiple colors using a phosphor may be used in combination.

<Method of manufacturing organic EL elements>
A method for forming a functional layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) in the present invention will be described.
The method for forming the functional layer is not particularly limited, and a conventionally known forming method such as a vacuum vapor deposition method or a wet method (also referred to as a wet process) can be used.
Examples of the wet method include a gravure printing method, a flexographic printing method, a screen printing method, and other printing methods, as well as a spin coating method, a casting method, an inkjet printing method, a die coating method, a blade coating method, a bar coating method, and a roll coating method. There are dip coating method, spray coating method, curtain coating method, doctor coating method, LB method (Langmuir-brodget method), etc., but the coating liquid can be applied easily and accurately, and it is highly productive. Therefore, it is more preferable to apply by an inkjet printing method using an inkjet head.

《Inkjet printing method》
Hereinafter, an example of the method of forming the functional layer by the inkjet printing method will be described with reference to the drawings.

FIG. 1 is a schematic view showing an example of a method for manufacturing an organic EL element using an inkjet printing method.

FIG. 1 shows a method of ejecting an organic material or the like (including an organic substance according to the present invention) forming a functional layer of an organic EL element onto a base material 2 using an inkjet printing apparatus provided with an inkjet head 30. An example is shown.

As shown in FIG. 1, as an example, while continuously transporting the base material 2, the organic material or the like is sequentially ejected as ink droplets onto the base material 2 by the inkjet head 30, and the organic EL element 1 is used. Form a functional layer of.

The inkjet head 30 applicable to the method for manufacturing an organic EL element according to the present invention is not particularly limited. For example, the ink pressure chamber has a diaphragm provided with a piezoelectric element, and the ink pressure chamber using the diaphragm has a diaphragm. It may be a shear mode type (piezo type) head that ejects the ink composition by a pressure change, or it has a heat generating element, and the heat energy from the heat generating element causes a sudden volume change due to the film boiling of the ink composition from the nozzle. It may be a thermal type head that ejects the ink composition.

An ink composition supply mechanism for injection is connected to the inkjet head 30. The ink composition is supplied to the inkjet head 30 by the tank 38A. In this example, the liquid level in the tank is kept constant so that the pressure of the ink composition in the inkjet head 30 is always kept constant. As a method, the ink composition is overflowed from the tank 38A and returned to the tank 38B by natural flow. The ink composition is supplied from the tank 38B to the tank 38A by the pump 31, and the liquid level of the tank 38A is controlled to be stable according to the injection conditions.

When returning the ink composition to the tank 38A by the pump 31, it is performed after passing through the filter 32. As described above, it is preferable that the ink composition is passed through a filter medium having an absolute filtration accuracy or a quasi-absolute filtration accuracy of 0.05 to 50 μm at least once before being supplied to the inkjet head 30.

Further, the ink composition can be forcibly supplied from the tank 36 and the cleaning solvent from the tank 37 can be forcibly supplied to the inkjet head 30 by the pump 39 in order to perform the cleaning work and the liquid filling work of the inkjet head 30. Such tank pumps may be divided into a plurality of such tank pumps with respect to the inkjet head 30, a branch of a pipe may be used, or a combination thereof may be used.

In FIG. 1, the pipe branch 33 is used. Further, in order to sufficiently remove the air in the inkjet head 30, the ink composition is forcibly sent from the tank 36 to the inkjet 30 by the pump 39, and the ink composition is extracted from the air bleeding pipe described below to be a waste liquid tank. It may be sent to 34.

2A and 2B are schematic external views showing an example of the structure of the inkjet head applicable to the inkjet printing method.

FIG. 2A is a schematic perspective view showing an inkjet head 100 applicable to the present invention, and FIG. 2B is a bottom view of the inkjet head 100.

The inkjet head 100 applicable to the present invention is mounted on an inkjet recording device (not shown), and includes a head chip that ejects ink from a nozzle, a wiring board on which the head chip is arranged, and this wiring. A drive circuit board connected via a substrate and a flexible substrate, a manifold for introducing ink into a channel of a head chip via a filter, a housing 56 in which a manifold is housed inside, and a bottom opening of the housing 56. The cap receiving plate 57 attached so as to close the above, the first and

second joints

81a and 81b attached to the first ink port and the second ink port of the manifold, and the third ink port attached to the third ink port of the manifold. It includes a 3-joint 82 and a cover member 59 attached to the housing 56. Further, mounting holes 68 for mounting the housing 56 on the printer main body side are formed.

Further, the cap receiving plate 57 shown in FIG. 2B is formed as a substantially rectangular plate whose outer shape is long in the left-right direction corresponding to the shape of the cap receiving plate mounting portion 62, and a plurality of nozzles are formed in the substantially central portion thereof. In order to expose the arranged nozzle plate 61, a long nozzle opening 71 is provided in the left-right direction. Further, regarding the specific structure inside the inkjet head shown in FIG. 2A, for example, FIG. 2 and the like described in Japanese Patent Application Laid-Open No. 2012-140017 can be referred to.

A typical example of the inkjet head is shown in FIGS. 2A and 2B, but in addition to the above, for example, Japanese Patent Application Laid-Open No. 2012-140017, Japanese Patent Application Laid-Open No. 2013-010227, Japanese Patent Application Laid-Open No. 2014-058171 and JP-A-2014 -097644, JP2015-142979, JP2015-142980, JP2016-002675, JP2016-002682, JP2016-107401, JP2017-109476 An inkjet head having the configuration described in Japanese Patent Application Laid-Open No. 2017-177626 and the like can be appropriately selected and applied.

《Inkjet head》
Inkjet heads applicable to the present invention include, for example, Japanese Patent Application Laid-Open No. 2012-140017, Japanese Patent Application Laid-Open No. 2013-010227, Japanese Patent Application Laid-Open No. 2014-058171, JP-A-2014-097644, and Japanese Patent Application Laid-Open No. 2015-142979. JP-A-2015-142980, JP-A-2016-002675, JP-A-2016-002682, JP-A-2016-107401, JP-A-2017-109476, JP-A-2017-177626, etc. An inkjet head having the configuration described in the above can be appropriately selected and applied.

The coating liquid used in the wet method may be a solution in which the material forming the functional layer is uniformly dissolved in the liquid medium, or a dispersion liquid in which the material is dispersed in the liquid medium as a solid content. As a dispersion method, dispersion can be performed by a dispersion method such as ultrasonic waves, high shear force dispersion, or media dispersion.
The liquid medium is not particularly limited, and for example, halogen-based solvents such as chloroform, carbon tetrachloride, dichloromethane, 1,2-dichloroethane, dichlorobenzene and dichlorohexanone, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone and n-propyl. Ketone solvents such as methyl ketone and cyclohexanone, aromatic solvents such as benzene, toluene, xylene, mesityrene and cyclohexylbenzene, aliphatic solvents such as cyclohexane, decalin and dodecane, ethyl acetate, n-propyl acetate, n-acetate Ester solvents such as butyl, methyl propionate, ethyl propionate, γ-butyrolactone, diethyl carbonate, ether solvents such as tetrahydrofuran and dioxane, amide solvents such as dimethylformamide and dimethylacetamide, methanol, ethanol, 1-butanol, Examples thereof include alcohol solvents such as ethylene glycol, nitrile solvents such as acetonitrile and propionitrile, dimethyl sulfoxide, water, or a mixed solution medium thereof.
The boiling point of these liquid media is preferably a boiling point lower than the temperature of the drying treatment from the viewpoint of quickly drying the liquid medium, specifically in the range of 60 to 200 ° C, more preferably 80 to 180 ° C. Is within the range of.

The coating liquid contains a surfactant depending on the purpose of controlling the coating range and suppressing the liquid flow (for example, the liquid flow that causes a phenomenon called coffee ring) associated with the surface tension gradient after coating. Can be done.
Examples of the surfactant include anionic or nonionic surfactants from the viewpoints of the influence of water contained in the solvent, leveling property, wettability to the substrate f1 and the like. Specifically, the surfactants listed in International Publication No. 08/146681, JP-A-2-41308, etc., such as fluorine-containing activators, can be used.

Similar to the film thickness, the viscosity of the coating film can be appropriately selected depending on the function required as the functional layer and the solubility or dispersibility of the organic material. Specifically, for example, 0.3 to 100 mPa. It can be selected within the range of s.
The film thickness of the coating film can be appropriately selected depending on the function required as the functional layer and the solubility or dispersibility of the organic material, and specifically, it can be selected in the range of, for example, 1 to 90 μm.
After forming the coating film by the wet method, it is possible to have a coating step of removing the above-mentioned liquid medium. The temperature of the drying step is not particularly limited, but it is preferable to perform the drying treatment at a temperature that does not damage the functional layer, the transparent electrode, or the base material. Specifically, it cannot be said unconditionally because it differs depending on the composition of the coating liquid and the like, but for example, the temperature can be set to 80 ° C. or higher, and the upper limit is considered to be a possible range up to about 300 ° C. The time is preferably about 10 seconds or more and 10 minutes or less. Under such conditions, drying can be performed quickly.

《Seal》
Examples of the sealing means used for sealing the organic EL element include a method of adhering the sealing member, the electrode, and the support substrate with an adhesive. The sealing member may be arranged so as to cover the display area of the organic EL element, and may be intaglio-shaped or flat-plate-shaped. Further, transparency and electrical insulation are not particularly limited.
Specific examples thereof 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, polysulfone and the like. 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 or a metal film can be preferably used because the organic EL element can be thinned. Furthermore, the polymer film had an oxygen permeability of 1 × 10 ^-3 mL / m ² / 24h or less measured by a method according to JIS K 7126-1987, and was measured by a method according to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably 1 × 10 ^-3 g / (m ² / 24h) or less.

Sandblasting, chemical etching, etc. are used to process the sealing member into a concave shape.
Specific examples of the adhesive include a photocurable and thermosetting adhesive having a reactive vinyl group of an acrylic acid-based oligomer and a methacrylic acid-based oligomer, and a moisture-curable adhesive such as 2-cyanoacrylic acid ester. be able to. In addition, heat and chemical curing type (two-component mixture) such as epoxy type can be mentioned. Further, hot melt type polyamide, polyester and polyolefin can be mentioned. In addition, a cation-curable type ultraviolet-curable epoxy resin adhesive can be mentioned.
Since the organic EL element may be deteriorated by heat treatment, it is preferable that the organic EL element can be adhesively cured from room temperature to 80 ° C. Further, the desiccant may be dispersed in the adhesive. A commercially available dispenser may be used to apply the adhesive to the sealing portion, or printing may be performed as in screen printing.

Further, it is also possible to preferably cover the electrode and the functional layer on the outside of the electrode on the side facing the support substrate with the functional layer sandwiched therein, and form a layer of an inorganic substance or an organic substance in contact with the support substrate to form a sealing film. .. In this case, the material for forming the film may be any material having a function of suppressing infiltration of a material that causes deterioration of the element such as moisture and oxygen, and for example, silicon oxide, silicon dioxide, silicon nitride or the like may be used. it can.

Further, in order to improve the fragility of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of an organic material. The method for forming these films is not particularly limited, and for example, 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. Legal, plasma CVD method, laser CVD method, thermal CVD method, coating method and the like can be used.

In the gas phase and liquid phase, an inert gas such as nitrogen or argon or an inert liquid such as fluorinated hydrocarbon or silicone oil may be injected into the gap between the sealing member and the display region of the organic EL element. preferable. It is also possible to create a vacuum. Further, a hygroscopic compound can 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, etc.) 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.), perchlorates (eg barium perchlorate, etc.) Magnesium perchlorate, etc.) and the like, and anhydrous salts are preferably used for sulfates, metal halides and perchlorates.

《Protective film, protective plate》
A protective film or protective plate may be provided on the outer side of the sealing film or the sealing film on the side facing the support substrate with the functional layer sandwiched in order to increase the mechanical strength of the element. In particular, when the sealing is performed by the sealing film, the mechanical strength thereof is not necessarily high, so it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, a glass plate, a polymer plate / film, a metal plate / film, etc. similar to those used for the sealing can be used, but the polymer film is lightweight and thin. Is preferably used.

<< Technology for improving light extraction >>
The organic EL element in the present invention 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 15% to 20% of the light generated in the light emitting layer. It is generally said that only a degree of light can be taken out. This is because light incident on the interface (intersection between the transparent substrate and air) at an angle θ equal to or greater than the critical angle causes total internal reflection and cannot be taken out of the element, and the transparent electrode or light emitting layer and the transparent substrate This is because the light is totally reflected between them, the light is waveguideed through the transparent electrode or the light emitting layer, and as a result, the light escapes toward the side surface of the element.

As a method for improving the efficiency of light extraction, for example, a method of forming irregularities on the surface of a transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (for example, US Pat. No. 4,774,435), the substrate A method of improving efficiency by providing light-collecting property (for example, Japanese Patent Application Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (for example, Japanese Patent Application 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 light emitting body and the light emitting body (for example, Japanese Patent Application Laid-Open No. 62-172691), which has a lower refractive index than the substrate between the substrate and the light emitting body. A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), a method of forming a diffraction lattice between layers (including, between the substrate and the outside world) of a substrate, a transparent electrode layer, or a light emitting layer (inclusive). JP-A-11-283751) and the like.

In the present invention, these methods can be used in combination with the organic EL element, but 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 and a transparent electrode layer. A method of forming a diffraction grating between any layer (including between the substrate and the outside world) of the light emitting layer or the light emitting layer can be preferably used.
When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the lower the refractive index of the medium, the higher the efficiency of extracting the light emitted from the transparent electrode to the outside. Become.
In the present invention, by combining these means, it is possible to obtain an element having higher brightness or excellent durability.

Examples of the low refractive index layer include airgel, 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, it is preferable that the low refractive index layer has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
Further, it is desirable that the thickness of the low refractive index medium is at least twice the wavelength in the medium. This is because the effect of the low refractive index layer diminishes when the thickness of the low refractive index medium becomes about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.

The method of introducing the diffraction grating into the interface where total reflection occurs or any medium is characterized in that the effect of improving the light extraction efficiency is high. This method is generated from the light emitting layer by utilizing 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. Of the generated light, the light that cannot go out due to total reflection between the layers is diffracted by introducing a diffraction grating in either layer or in the medium (inside the transparent substrate or in the transparent electrode). , Trying to get the light out.
It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because the light emitted by the light emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating that has a periodic refractive index distribution only in a certain direction, only the 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 the light extraction efficiency is improved.
The position where the diffraction grating is introduced may be either between layers or in a medium (inside a transparent substrate or in a transparent electrode), but it is desirable that the diffraction grating is introduced in the vicinity of an organic 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 the light in the medium. As for the arrangement of the diffraction grating, it is preferable that the arrangement is repeated two-dimensionally, such as a square lattice shape, a triangular lattice shape, and a honeycomb lattice shape.

《Condensing sheet》
The organic EL element in the present invention is processed so as to provide a structure on a microlens array, for example, on the light extraction side of a support substrate (substrate), or by combining with a so-called condensing sheet, for example, an element By condensing light in the front direction with respect to the light emitting surface, it is possible to increase the brightness in a specific direction.
As an example of a microlens array, a quadrangular pyramid having a side of 30 μm and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate. One side is preferably in the range of 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and it is colored, and if it is too large, the thickness becomes thick, which is not preferable.

As the condensing sheet, for example, a sheet that has been put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness increasing film (BEF) manufactured by Sumitomo 3M Ltd. can be used. The shape of the prism sheet may be, for example, a base material having a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or a shape having a rounded apex angle and a random change in pitch. Shape or other shape may be used.
Further, the light diffusing plate / film may be used in combination with the condensing sheet in order to control the light emission angle from the organic EL element. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

《Use》
The organic EL element in the present invention can be used as a display device, a display, and various light emitting light sources.
As the light source, for example, a lighting device (household lighting, in-car lighting), a backlight for a clock or a liquid crystal, a signboard advertisement, a signal, a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processor, light Examples thereof include, but are not limited to, a light source for a sensor, but the light source can be effectively used as a backlight for a liquid crystal display device and a light source for lighting.
If necessary, the organic EL device of the present invention may be patterned by a metal mask, an inkjet printing method, or the like at the time of film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or all the layers of the device may be patterned. In the fabrication of the device, a conventionally known method is used. Can be done.

<< One aspect of lighting equipment >>
An aspect of the lighting device provided with the organic EL element in the present invention will be described.
The non-light emitting surface of the organic EL element is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (Luxtrac LC0629B manufactured by Toa Synthetic Co., Ltd.) is used as a sealing material around the glass substrate. ) Is applied, this is placed on the cathode and brought into close contact with the transparent support substrate, UV light is irradiated from the glass substrate side, the curing is performed, and the sealing is performed. Can be formed.
FIG. 3 shows a schematic view of the lighting device, and the organic EL element 101 according to the present invention is covered with a glass cover 102 (note that the sealing operation with the glass cover brings the organic EL element 101 into contact with the atmosphere. The glove box was carried out in a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).
FIG. 4 shows a cross-sectional view of the lighting device. In FIG. 4, reference numeral 105 indicates a cathode, reference numeral 106 indicates an organic EL layer, and reference numeral 107 indicates 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.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass", respectively.

In the following examples, OFPO represents 1H, 1H, 5H-octafluoro-1-pentanol. Further, as the compounds B3, B4 and B5, those manufactured by Aldrich are used.
The compounds B1 to B10 used in the examples are as follows.

(1) Example 1
In Example 1, the electron-only device shown below (also referred to as a single-charge device, hereinafter referred to as “EOD”) was produced, and its reverse current was evaluated.

<Preparation of coating liquid 101 for cathode>
100 mL of a 1000 mM silver nitrate aqueous solution was placed in a beaker. In another beaker, 3 g of a non-volatile organic substance (Disperbic 190 (trade name): manufactured by Big Chemie, 40% aqueous solution) was taken as a dispersant, and 100 g of pure water was added thereto.
To a beaker containing an aqueous silver nitrate solution, 27 g of a Disperbic 190 aqueous solution prepared in another beaker was added. After sufficiently stirring, 15 g of triethanolamine was added, and the mixture was stirred at 60 ° C. for 6 hours. Then, centrifugation and purification were performed three times. Pure water was added to the obtained silver particles to make a total of 50 g, to obtain a metal fine particle dispersion 101 in which silver particles were dispersed.
10 g of the obtained metal fine particle dispersion 101 was prepared, 1.1 g of pure water and 2.3 g of 2-propanol were added to the metal fine particle dispersion 101 and stirred well to obtain a cathode coating liquid 101. The ratio of the solvent in this coating liquid is 2-propanol 0.2 with respect to water 0.8.

<Preparation of EOD1-1 for evaluation>
(Formation of anode)
ITO (indium tin oxide) was formed into a film having a thickness of 120 nm on a glass substrate having a length of 50 mm, a width of 50 mm, and a thickness of 0.7 mm to perform patterning to form an anode made of an ITO transparent electrode. Then, it was ultrasonically washed with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone washed for 5 minutes.

(Formation of hole block layer)
Next, the formed transparent substrate was fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus.
Each of the resistance heating boats for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent materials of each layer in the optimum amount for manufacturing the device. The resistance heating boat for vapor deposition was made of tungsten or molybdenum.
After reducing the vacuum to a degree of vacuum of 1 × 10 ^-4 Pa, calcium was vapor-deposited at a film formation rate of 0.2 nm / s at 5 nm to form a hole block layer.

(Formation of electron transport layer)
Next, in an atmospheric environment, compound B1 (organic substance), which is a conductive material, was dissolved in OFPO at a concentration of 1.3% by mass, and on a substrate on which a hole block layer was formed by a spin coating method at 750 rpm for 30 seconds. Compound A1 was formed in a film having a thickness of 120 nm and dried at 100 ° C. for 30 minutes to form an electron transport layer.

(Cathode formation)
The above-mentioned coating liquid 101 for a cathode was applied to a substrate having a film formed up to the electron transport layer using a dispenser to form a cathode. The amount of liquid and the coating rate were adjusted in advance so that the film thickness after drying would be 200 nm. After application, it was dried in a constant temperature bath at 120 ° C. for 30 minutes.
To measure the above film thickness, apply a coating liquid on a separately prepared glass substrate, peel off a part of the film, and use Bruker's stylus profiling system Dektak to remove the step between the peeled part and the part where the film remains. Measured using.

(Formation of sealing layer)
PET film of aluminum foil and the thickness 100μm thick 20μm was laminated film (Panac Inc.) Oxygen permeability ^{0.001mL / (m 2 · 24h ·} atm) or less, the water vapor permeability of 0.001 g / (m ² · 24h) and a flexible gas barrier film having the gas barrier properties. A thermosetting liquid adhesive (epoxy resin) was formed as a sealing resin layer on the surface of the aluminum foil of this film to a thickness of 25 μm. Then, the gas barrier film provided with the sealing resin layer was superposed on the device produced up to the produced cathode. At this time, the sealing resin layer forming surface of the gas barrier film was continuously superposed on the sealing surface side of the organic EL element so that the ends of the anode and the ejection portion of the cathode were exposed to the outside.
Next, the sample to which the gas barrier film was attached was placed in a decompression device, pressed under a decompression condition of 0.1 MPa at 90 ° C., and held for 5 minutes. Subsequently, the sample was returned to the atmospheric pressure environment and further heated at 90 ° C. for 30 minutes to cure the adhesive.
The sealing step is based on JIS B 9920 under atmospheric pressure and a nitrogen atmosphere with a moisture content of 1 ppm or less, the measured cleanliness is class 100, the dew point temperature is -80 ° C or less, and the oxygen concentration is 0.8 volume. It was carried out at atmospheric pressure of ppm or less.
Through the above steps, evaluation EOD1-1 was prepared.

<Preparation of EOD1-2 to 1-14 for evaluation>
In the preparation of the evaluation EOD1-1, the compound B1 used in the formation of the electron transport layer was changed to the organic matter (organic material under the electrode) shown in Table I below.
Compound B3 was used by diluting the stock solution to 1.3% by mass with OFPO. B4, B5 and A25 were dissolved in normal butyl acetate in an amount of 1.5% by mass and used. Other than that, evaluation EOD1-2 to 1-14 were prepared in the same manner.

<Reverse current evaluation of evaluation EOD>
Here, the absolute value of the current density [mA / cm ^{2] at −5 V of each evaluation EOD was measured.} However, the limit current value is set to ± 250 mA / cm ² .
Table I shows the glass transition point (Tg) of the organic matter (organic material under the electrode), the molecular weight of the organic matter (organic material under the electrode) (number average molecular weight in the case of polymer), and E [cal / in formula (1). mol], the calculation result and the measurement result of the reverse current value at -5V are shown. Since the glass transition point of B3 was 0 ° C. or lower, E is calculated assuming that it is 0 ° C. (273K) this time.

As shown in the above results, in the EOD (comparative example) using an organic substance in which E is less than 3300 cal / mol, a large amount of reverse current flows and the semiconductor property is not obtained. Further, it can be seen that the compounds B3 to B5 are leaking even though they are insulating materials. As a precaution, as a result of reverse current evaluation at -5V for EOD 1-3 to 1-5 with Ag cathode formed by vacuum deposition, 0.01 mA / cm ^{2 for all EODs.} It was confirmed that the values were as follows. Further, for EOD (the present invention) using an organic substance having an E of 3300 cal / mol or more, the reverse current is 0.2 mA / cm ² or less, which shows that electric leakage is prevented. In particular, the reverse current value is very small in EOD using an organic substance (the present invention) in which E is 4000 cal / mol or more.

[Example 2]
In Example 2, the organic EL device shown below was produced, and its reverse current value was evaluated.

<Manufacturing of organic EL element 2-1 for evaluation>
As shown below, the anode / hole injection layer / hole transport layer / light emitting layer / block layer / electron transport layer / cathode are laminated on the substrate and then sealed, and the bottom emission type organic EL element 2- 1 was produced.

(Preparation of base material)
First, an atmospheric pressure plasma discharge treatment apparatus having the configuration described in JP-A-2004-68143 is used on the entire surface of the polyethylene naphthalate film (manufactured by Teijin DuPont, hereinafter abbreviated as PEN) on the side where the anode is formed. Therefore, an inorganic gas barrier layer made of SiO _x was formed so as to have a layer thickness of 500 nm. Accordingly, the oxygen permeability of ^{0.001mL / (m 2 · 24h ·} atom) or less, to produce a water vapor permeability of 0.001g / (m ² · 24h) flexible substrate having the gas barrier properties.

(Formation of anode)
An ITO (indium tin oxide) having a thickness of 120 nm was formed on the base material by a sputtering method and patterned by a photolithography method to form an anode. The pattern was set so that the area of the light emitting region was 5 cm × 5 cm.

(Formation of hole injection layer)
The base material on which the anode was formed was ultrasonically washed with isopropyl alcohol, dried with dry nitrogen gas, and treated with UV ozone for 5 minutes. Then, on the base material on which the anode is formed, a dispersion of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS) prepared in the same manner as in Example 16 of Japanese Patent No. 4509787 is isopropyl alcohol. The 2% by mass solution diluted with (1) was applied by an inkjet method and dried at 80 ° C. for 5 minutes to form a hole injection layer having a layer thickness of 40 nm.

(Formation of hole transport layer)
Next, the base material on which the hole injection layer was formed was coated by an inkjet method using a coating solution for forming a hole transport layer having the following composition in an atmospheric environment, dried at 130 ° C. for 30 minutes, and layered to a thickness. A hole transport layer of 30 nm was formed.

(Coating liquid for forming hole transport layer)
Hole transport material (weight average molecular weight Mw = 80000) (Compound A35)
10 parts by mass Chlorobenzene 3000 parts by mass

(Formation of light emitting layer)
Next, the base material on which the hole transport layer was formed was applied by an inkjet method using a coating liquid for forming a light emitting layer having the following composition, and dried at 120 ° C. for 30 minutes to form a light emitting layer having a layer thickness of 50 nm. ..

(Coating liquid for forming a light emitting layer)
Host compound (Compound B7) 10 parts by mass Phosphorescent material (Compound B8) 1 part by mass Fluorescent material (Compound B9) 0.1 parts by mass Normal butyl acetate 2200 parts by mass

(Formation of electron transport layer)
Next, using a coating liquid for forming an electron transport layer having the following composition, the coating liquid was applied by an inkjet method and dried at 80 ° C. for 30 minutes to form an electron transport layer having a layer thickness of 30 nm.

(Coating liquid for forming electron transport layer)
Electron transport material (organic matter) (Compound B1) 6 parts by mass OFPO 2000 parts by mass

(Sealing)
A sealing base material was adhered to the laminate formed by the above steps using a commercially available roll laminating apparatus.
As a sealing base material, a flexible aluminum foil (manufactured by Toyo Aluminum K.K. Co., Ltd.) with a thickness of 30 μm is bonded to a layer thickness of 1.5 μm using a two-component reaction type urethane adhesive for dry lamination. An agent layer was provided, and a 12 μm-thick polyethylene terephthalate (PET) film was laminated.
As the sealing adhesive, a thermosetting adhesive was uniformly applied to a thickness of 20 μm along the adhesive surface (glossy surface) of the aluminum foil of the sealing base material using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Further, the sealing base material is moved to a nitrogen atmosphere having a dew point temperature of -80 ° C or less and an oxygen concentration of 0.8 ppm and dried for 12 hours or more so that the water content of the sealing adhesive is 100 ppm or less. It was adjusted.
As the thermosetting adhesive, an epoxy-based adhesive in which the following (A) to (C) were mixed was used.
(A) Bisphenol A Diglycidyl Ether (DGEBA)
(B) Dicyanodiamide (DICY)
(C) Epoxy adduct-based curing accelerator The sealing base material is adhered to and arranged on the laminated body, and a crimping roll is used, the crimping roll temperature is 100 ° C., the pressure is 0.5 MPa, and the device speed is 0.3 m / It was tightly sealed under the crimping condition of min.
As described above, the evaluation organic EL element 2-1 was manufactured.

<Manufacturing of organic EL elements 2-2 to 2-9 for evaluation>
In the production of the organic EL element 2-1 for evaluation, the compound B1 used in the formation of the electron transport layer was evaluated in the same manner except that the compound B1 was changed to the organic matter (organic material under the electrode) shown in Table II below. Organic EL elements 2-2 to 2-9 for use were manufactured.

<Reverse current evaluation of organic EL element for evaluation>
Here, the absolute value of ^{the current density [mA / cm 2} ] at −5 V of each evaluation organic EL element was measured. However, the limit current value is set to ± 250 mA / cm ² .
Table II shows the glass transition point (Tg) of the organic matter (organic material under the electrode), the molecular weight of the organic matter (organic material under the electrode) (number average molecular weight in the case of polymer), and E [cal / mol] in the formula (1). ], The calculation result and the measurement result of the reverse current value at -5V are shown.

As shown in the above results, an organic EL device (comparative example) using an organic substance having an E of less than 3300 cal / mol has a large amount of reverse current flowing and does not have semiconductor characteristics. On the other hand, in the organic EL device (invention) using an organic substance having E of 3300 cal / mol or more, the device suddenly has semiconductor characteristics, and the reverse current value is 0.2 mA / cm ² or less in each case. It has become. In particular, the reverse current value is very small in an organic EL device using an organic substance (the present invention) in which E is 4000 cal / mol or more.

(3) Example 3
In Example 3, a hole-only device (hereinafter referred to as “HOD”) shown below was produced, and its reverse current value was evaluated.

<Preparation of HOD3-1 for evaluation>
(Formation of anode)
The anode was formed in the same procedure as the evaluation EOD1-1.

(Formation of hole injection layer)
Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) diluted to 70% with pure water on the transparent substrate formed above in an air environment. The solution was formed into a film by a spin coating method at 3000 rpm for 30 seconds, and then dried at 200 ° C. for 1 hour to provide a hole injection layer having a film thickness of 30 nm.

(Formation of hole transport layer)
Next, in an air environment, compound B10 was dissolved in dichlorobenzene at a concentration of 1.5% by mass, and compound B10 was formed to a thickness of 120 nm by a spin coating method at 1000 rpm for 30 seconds at 100 ° C. It was dried for 30 minutes to form a hole transport layer.

(Cathode formation)
The cathode was formed in the same procedure as the evaluation EOD1-1.

(Sealing)
Sealing was performed in the same procedure as for evaluation EOD1-1.

<Preparation of HOD3-2 to 3-10 for evaluation>
In the preparation of the evaluation HOD3-1, the evaluation EODs 3-2 to 3-10 were prepared in the same manner except that the compound B10 used for forming the functional layer was changed to the compound shown in Table III.

<Reverse current evaluation of HOD for evaluation>
Here, the absolute value of the current density [mA / cm ^{2] at −5 V of each evaluation HOD was measured.} However, the limit current value is set to ± 250 mA / cm ² .
Table III shows the glass transition point (Tg) of the organic matter (organic material under the electrode), the molecular weight of the organic matter (organic material under the electrode) (number average molecular weight in the case of polymer), and E [cal / mol] in the formula (1). ], The calculation result and the measurement result of the reverse current value at -5V are shown.

As shown in the above results, in HOD (comparative example) using an organic substance having E of less than 3300 cal / mol, a large amount of reverse current flows and the semiconductor property is not obtained. On the other hand, in HOD (the present invention) using an organic substance having E of 3300 cal / mol or more, the device suddenly has semiconductor characteristics, and the reverse current value is 0.2 mA / cm ² or less in each case. There is. In particular, the reverse current value is very small in HOD using an organic substance (the present invention) in which E is 4000 cal / mol or more.

The present invention can be used for an organic electroluminescence element that does not cause an electric leakage abnormality even when an electrode is applied and formed on an organic film formed without using cross-linking.

1, 101 Organic EL element 2

Base material

30, 100

Inkjet head

31, 39 Pump 32 Filter 33 Piping branch 34 Waste liquid tank 35

Control unit

36, 37, 38A, 38B Tank 56 Housing 57 Cap receiving plate 59 Cover member 61 Nozzle plate 62 Cap receiving plate mounting part 68 Mounting hole 71 Nozzle opening 81a 1st join 81b 2nd joint 82 3rd joint 102 Glass cover 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen gas 109 Water catching agent

Claims

An organic electroluminescence device including a base material, an electrode 1, a functional layer, and an electrode 2 in this order.
The functional layer is composed of a single layer or a plurality of layers.
Of the functional layers, the layer in contact with the electrode 2 is made of an organic film, and the organic substances contained in the organic film are not crosslinked.
E derived from the following formula (1) defined by the glass transition point and molecular weight of the organic substance is 3300 cal / mol or more, and
An organic electroluminescence device in which the electrode 2 is a coating film.
Equation (1): E = 0.5 × R × Tg × ln (M)
[In the formula, R [cal / K · mol] represents the gas constant, Tg represents the glass transition point [K] of the organic substance, and M represents the molecular weight of the organic substance (when the organic substance is a polymer, the number average molecular weight). ]
The organic electroluminescence device according to claim 1, wherein in the formula (1), the E is 4000 cal / mol or more.
The organic electroluminescence device according to claim 1 or 2, wherein the glass transition point (Tg) of the organic substance in the formula (1) is 470 K or more.
The organic electroluminescence device according to any one of claims 1 to 3, wherein in the formula (1), the molecular weight (M) of the organic substance is 40,000 or more.
The organic electroluminescence device according to claim 4, wherein in the formula (1), the molecular weight (M) of the organic substance is 90,000 or more.