JP2021111494A - Organic electroluminescent element and method for manufacturing the same - Google Patents

Abstract

To provide an organic electroluminescent element that can perform high-contrast light emission and high-definition image formation without requiring providing a bank (dike) with a special material, and has high characteristics including brightness, life, and external quantum, and a method for manufacturing the same.SOLUTION: An organic electroluminescent element of the present invention is an organic electroluminescent element having an anode, at least an organic function layer, and a cathode on a substrate, and has a light-emitting part and a non-light-emitting part in an image display area including at least the organic function layer. The light-emitting part has a luminescent layer containing a luminescent dopant. The non-light-emitting part has a non-luminescent layer not containing the luminescent dopant in an amount allowing visual recognition of a luminous phenomenon, and the thickness of the non-luminescent layer of the non-light-emitting part is twice or more thicker than the thickness of the luminescent layer of the light-emitting part.SELECTED DRAWING: Figure 1

Description

The present invention relates to an organic electroluminescent device and a method for producing the same.
More specifically, it is possible to emit high-contrast light and display high-resolution images without the need to provide a bank (embankment) made of a special material, and organic with a high level of characteristics such as brightness, lifetime, and external quantum effect. Regarding electroluminescence elements and the like.

In recent years, organic electroluminescence elements (hereinafter abbreviated as "organic EL elements") using electroluminescence of organic compounds (hereinafter abbreviated as "EL") have rapidly become widespread in various fields. This organic EL element is a thin film type completely solid element capable of emitting light at a low voltage of about several V to several tens of V, and has many excellent features such as high brightness, high emission efficiency, thinness, and light weight. Have.

In the organic EL element, electrons and holes are injected into the light emitting layer from the electron injection electrode and the hole injection electrode, respectively, and the injected electrons and holes are bonded in the light emitting layer to bring the organic compound into an excited state. , This organic compound emits light when it returns from the excited state to the ground state, and has an advantage that it can be driven with a low voltage.
Taking advantage of the fact that it emits light on a surface, its application fields are being energetically studied as a surface light emitting body such as a display device, a display, and an illumination light source as a thin and flexible lighting application.

Conventionally, as a method for manufacturing an organic EL element, a method of manufacturing by a dry process method using a chemical vapor deposition method, a vacuum deposition method, or the like is widely known, but most of these dry processes are used in vacuum equipment or the like. Since a large-scale facility is required, the cost increases, and it is difficult to manufacture a large-area organic EL element due to the equipment.

In response to the above problems, as a method for manufacturing an organic EL element, a coating method that realizes energy saving, large area, light weight / thin film, high forming accuracy, and high productivity, for example, an offset printing method and a gravure printing method. , A study of "printed electronics" that forms various organic functional layers (hereinafter, also simply referred to as "organic layers") constituting an organic EL element by using a wet process such as a screen printing method or an inkjet printing method. Is being actively done.

However, when each organic functional layer is to be laminated by a wet process, elution of the already formed lower layer becomes a problem.
When the lower layer is eluted, not only the merit of laminating the organic functional layer is lost, but also there is a problem that the organic EL element is short-circuited due to the reduction of the uniformity of the layer thickness and the deterioration is accelerated due to the concentration of the electric field. rice field.

As a method for dealing with such a problem, for example, in Patent Document 1, in the step of forming an organic light emitting layer, a host layer is provided by a wet process, and a solvent and a guest material for dissolving the host layer are injected therein. By doing so, a method of forming a host-guest layer only on the surface layer portion of the light emitting layer is disclosed.
However, this method has a problem that the life of the organic EL element becomes insufficient because only the surface of the host layer is dissolved.

Further, in the method disclosed in Patent Document 2, a predetermined light emitting pattern showing characters or pictures by different at least one of a light emitting color and a light emitting brightness in at least two light emitting regions among a plurality of light emitting regions. However, since the light emitting layer includes a non-light emitting region and the non-light emitting region is formed of two kinds of coating liquids, there is a problem that the contrast between the light emitting portion and the non-light emitting portion becomes insufficient. rice field.

The solvent used when forming the organic layer by the solution treatment technique such as inkjet printing disclosed in Patent Document 3 has a problem that the solubility of the compound is only increased.

The ink having physical characteristics suitable for inkjet disclosed in Patent Document 4 has a problem that the dot diameter of the ink becomes large when it gets wet and spreads, and it is difficult to separately paint RGB without a bank (embankment).

Japanese Unexamined Patent Publication No. 2010-192137 Japanese Patent No. 6122491 Japanese Patent No. 6130321 Japanese Patent No. 6106917

The present invention has been made in view of the above problems and situations, and the problem to be solved is that it is not necessary to provide a bank (embankment) made of a special material, and high-contrast light emission and high-resolution image formation are possible. It is an object of the present invention to provide an organic electroluminescence element having a high level of characteristics such as brightness, lifetime and external quantum efficiency, and a method for manufacturing the same.

In order to solve the above problems, the present inventor has made the thickness of the non-light emitting layer of the non-light emitting portion thicker than that of the light emitting layer of the light emitting portion in the process of examining the cause of the above problem, thereby causing non-emission. We have found that the layer can have a bank-like function and thereby solve the problem, and have reached the present invention.
That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. An organic electroluminescence device having an anode, at least an organic functional layer, and a cathode on a substrate.
It has a light emitting part and a non-light emitting part in the image display area including at least the organic functional layer.
The light emitting portion has a light emitting layer containing a light emitting dopant and has a light emitting layer.
The non-light emitting portion has a non-light emitting layer that does not contain an amount of a light emitting dopant that allows the light emitting phenomenon to be visually recognized, and has a non-light emitting layer.
An organic electroluminescence device characterized in that the thickness of the non-light emitting layer of the non-light emitting portion is 1.5 times or more thicker than the thickness of the light emitting layer of the light emitting portion.

2. The organic electroluminescence device according to item 1, wherein the light emitting portion has a portion formed by a solvent dissolving action on the upper side of the surface of the light emitting layer.

3. 3. When the thickness of the non-light emitting layer of the non-light emitting portion is A and the thickness of the light emitting layer of the light emitting portion is B, the following relational expression (1) is satisfied. The organic electroluminescence device described in the section.
Relational expression (1): A / B = 1.5 to 5.5

4. The organic electroluminescence device according to any one of items 1 to 3, wherein the light emitting layer is a layer containing a host compound and a light emitting dopant.

5. Item 2. The organic electroluminescence element described.

6. The organic electroluminescence device according to Item 5, wherein the host compound contained in the organic functional layer, which is a non-light emitting layer, has a molecular weight of 1000 or less.

7. The organic electroluminescence device according to any one of items 1 to 6, wherein a hole transport layer is provided under the non-light emitting layer.

8. Items 1 to 7 are characterized in that the light emitting units are arranged in dots in the image display unit region when viewed from a direction perpendicular to the surface in the image display unit region. The organic electroluminescence device according to any one of the items.

9. A method for manufacturing an organic electroluminescent device according to any one of items 1 to 7, wherein the organic electroluminescent device is manufactured.
In the formation of the non-light emitting portion and the light emitting portion,
A step of forming the non-emissive layer by an inkjet printing method or a wet process other than the inkjet printing method, and
It has a step of forming the light emitting layer containing a light emitting dopant by an inkjet printing method, and
An organic electroluminescence element characterized in that the difference between the solubility parameter value of the solvent of the compound-containing liquid used for forming the non-light emitting layer and the solubility parameter value of the solvent of the ink used for forming the light emitting layer is 2 or less. Production method.

By the above means of the present invention, it is possible to emit high-contrast light and form a high-resolution image without the need to provide a bank (embankment) made of a special material, and the level of characteristics such as brightness, lifetime, and external quantum efficiency. It is possible to provide an organic electroluminescence device having a high resolution and a method for producing the same.
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 organic electroluminescence element of the present invention has a light emitting portion and a non-light emitting portion on a substrate at least in an image display region including an organic functional layer, and the light emitting portion has a light emitting layer containing a light emitting dopant. However, the non-light emitting portion has a non-light emitting layer that does not contain an amount of luminescent dopant that allows the light emitting phenomenon to be visually recognized, and the thickness of the non-light emitting layer of the non-light emitting portion is such that the light emitting portion of the light emitting portion. By being 1.5 times or more thicker than the layer thickness, the non-light emitting layer plays the role of a bank (embankment) in the process of forming the light emitting layer, so that the light emitting pixels are neatly formed in a predetermined shape. Therefore, it is presumed that high-contrast light emission and high-resolution image formation were possible, and characteristics such as brightness, lifetime, and external quantum effect could be brought to a high level.

In particular, when the light emitting layer is formed by using the inkjet printing method, the effect of the present invention becomes remarkable, so that the above mechanism of action is inferred. The detailed mechanism of action will be described later as appropriate.

(A): Schematic cross-sectional view of a typical configuration of the organic EL element 1 of the present invention (b): The image display area when viewed from a direction perpendicular to the surface of 1A in the image display area of the organic EL element 1. Conceptual diagram showing that the light emitting part is arranged in a dot shape in 1A of the inside. The conceptual diagram which shows the formation method of the light emitting layer in the light emitting part which concerns on this invention. A conceptual diagram showing the relationship between the thickness of the light emitting layer and the non-light emitting layer of the light emitting portion according to the present invention. Conceptual diagram showing a method for manufacturing an organic EL element by an inkjet printing method.

The organic electroluminescence element of the present invention is an organic electroluminescence element having an anode, at least an organic functional layer, and a cathode on a substrate, and has a light emitting portion within an image display region including at least the organic functional layer. The non-light emitting unit has a light emitting layer containing a light emitting dopant, and the non-light emitting unit has a non-light emitting layer containing no light emitting dopant in an amount in which a light emitting phenomenon can be visually recognized. Moreover, the thickness of the non-light emitting layer of the non-light emitting portion is 1.5 times or more thicker than the thickness of the light emitting layer of the light emitting portion.
This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, it is preferable that the light emitting portion has a portion formed above the surface of the light emitting layer by a solvent dissolving action from the viewpoint of exhibiting the effect of the present invention.
Further, when the thickness of the non-light emitting layer of the non-light emitting portion is A and the thickness of the light emitting layer of the light emitting portion is B, satisfying the relational expression (1) satisfies the contrast and the uniformity of light emission. It is preferable in that a large effect can be obtained.

Further, it is preferable that the light emitting layer is a layer containing a host compound and a light emitting dopant from the viewpoint of luminous efficiency and brightness. On the other hand, it is preferable that the non-light emitting layer is an organic functional layer containing a host compound but not an amount of a light emitting dopant that induces a light emitting phenomenon from the viewpoint of contrast and the like.

Further, it is preferable that the molecular weight of the host compound contained in the organic functional layer, which is the non-light emitting layer, is 1000 or less from the viewpoint of solubility in a solvent and the like.
Further, it is also preferable that the hole transport layer is provided under the non-light emitting layer in terms of hole transport to the adjacent light emitting layer.

In the organic electroluminescence device of the present invention, when viewed from a direction perpendicular to the surface in the image display portion region, the light emitting portion is arranged in a dot shape in the image display portion region. It is preferable from the viewpoint of displaying an image that draws a line composed of dots and various figures.

The method for producing an organic electroluminescence element of the present invention includes a step of forming the non-light emitting layer by a wet process other than an inkjet printing method or an inkjet printing method in forming the non-light emitting portion and the light emitting portion, and a luminescent dopant. It has a step of forming the light emitting layer containing The difference from the solubility parameter value (SP value) of the ink solvent is 2 or less.

As an embodiment, it is preferable to have a step of forming a light emitting portion containing the light emitting dopant by an inkjet method from the viewpoint of accuracy and simplicity.
By the above manufacturing method, the layers are well compatible with each other, the solvent for forming the light emitting layer dissolves the non-light emitting layer with high accuracy, and the luminescent dopant is dispersed in the dissolved portion of the non-light emitting layer at a desired position. It is preferable in that it can emit light.

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.

1. 1. Outline of the Organic Electroluminescence Device of the Present Invention The organic electroluminescence device of the present invention (hereinafter, also referred to as “organic EL device”) has an anode, at least an organic functional layer, and a cathode on a substrate. The element, which has a light emitting portion and a non-light emitting portion in an image display region including at least the organic functional layer, the light emitting portion has a light emitting layer containing a light emitting dopant, and the non-light emitting portion has a light emitting layer. 1. It has a non-light emitting layer that does not contain an amount of luminescent dopant that allows the light emission phenomenon to be visually recognized, and the thickness of the non-light emitting layer of the non-light emitting portion is larger than the thickness of the light emitting layer of the light emitting portion. It is characterized by being 5 times or more thick.

(1.1) Basic Configuration of Organic EL Element The following shows examples of various configuration forms having a basic constituent layer of the organic EL element. The relationship between the various layers described below and the image display region, the light emitting portion, and the non-light emitting portion according to the present invention will be described later.
(I) Anodic / non-light emitting layer / light emitting layer / cathode (ii) anode / hole injection layer / non-light emitting layer / light emitting layer / electron injection layer / cathode (iii) anode / hole injection layer / hole transport layer / Non-light emitting layer / light emitting layer / electron transport layer / electron injection layer / cathode (iv) anode / hole injection layer / hole transport layer / electron blocking layer / non-light emitting layer / light emitting layer / hole blocking layer // electron transport Layer / electron injection layer / cathode The above basic configuration does not necessarily represent the hierarchical relationship of the layers, and in the present invention, as shown in FIG. 1, the non-light emitting layer of the non-light emitting portion plays the role of a bank. Therefore, in the above configuration example, the non-light emitting layer is not laminated on the light emitting surface on the light emitting surface side of the light emitting layer, and is arranged at least on the side surface side of the light emitting layer in parallel with the light emitting layer. Will be done.

(Organic functional layer)
The "organic functional layer" refers to a layer containing an organic compound that expresses a predetermined function. It is also simply referred to as an "organic compound layer" or an "organic layer".
Examples of the organic functional layer constituting the organic EL element of the present invention include a hole transport layer, a light emitting layer, a non-light emitting layer, an electron transport layer, and the like in the above layer structure, and other holes. If an organic compound contained in a constituent layer of an organic EL element such as an injection layer or an electron injection layer is contained, it is defined as an organic functional layer according to the present invention.

Further, when an organic compound is used for the anode buffer layer, the cathode buffer layer, etc., the anode buffer layer, the cathode buffer layer, etc. also form the organic functional layer, respectively.
The organic functional layer also includes a layer containing an organic EL element material or the like that can be used as a constituent layer of the organic EL element.

(1.2) Image display area, light emitting part and non-light emitting part FIG. 1A shows a schematic cross-sectional view of a typical configuration of the organic EL element 1 of the present invention. also. FIG. 1B shows that the light emitting portions are arranged in dots in the image display area 1A when viewed from a direction perpendicular to the surface of the image display area 1A of the organic EL element 1. A conceptual diagram is shown. From the viewpoint of image display, it is preferable that they are arranged so that a line composed of a plurality of dots and various figures can be drawn. Further, it is also preferable that the dots are formed and arranged as minute pixels that cannot be visually recognized as dots when the image on the image display device is viewed by a normal visual observation method.

Here, "in the image display area" is an area including a light emitting part and a non-light emitting part involved in image display in the organic EL display device, and is involved in light emission and non-light emission contributing to image display in the organic EL element. Refers to a two-dimensional (two-dimensional) region and a three-dimensional (three-dimensional) region in which an organic functional layer and a transparent electrode that transmits light are laminated.

In FIG. 1, the organic functional layer unit 1U includes at least one light emitting layer, and visually recognizes a light emitting unit 6 having a light emitting layer 6a containing at least a light emitting dopant and an organic functional layer 6b and a light emitting phenomenon in the image display region 1A. It has a non-light emitting unit 7 having a non-light emitting layer 7a that does not contain a possible amount of luminescent dopant. The portion of the organic functional layer 6b may be the same as or different from the organic functional layer (for example, the electron transport layer) arranged above the non-light emitting layer 7a.

(1.2.1) Light-emitting part and light-emitting layer In FIG. 1, the light-emitting part 6 according to the organic EL element 1 of the present invention includes a light-emitting layer 6a and an organic functional layer part 6b containing at least a light-emitting dopant. Have.
The light emitting layer 6a is a layer in which electrons injected from the electrode or electron transport layer and holes injected from the electrode or hole transport layer recombine to emit light.
The light emitting layer 6a contains at least a light emitting dopant, and preferably a layer containing a host compound and a dopant from the viewpoint of luminous efficiency and brightness.
The organic functional layer portion 6b of the light emitting portion 6 is preferably a portion in which the organic functional layer is formed at a pore portion formed by a solvent dissolving action above the surface of the light emitting layer.

Since the non-light emitting portion 7 functions as a bank (embankment), it is preferable in that an orderly light emitting portion, that is, dot-shaped pixels can be formed as shown in FIGS. 1 (A) and 1 (B).
That is, when viewed from a direction perpendicular to the surface in the image display area, as shown in FIG. 1B, the light emitting units are arranged in dots in the image display area. preferable. That is, as described above, it is preferable from the viewpoint of image display that they are arranged so that a line composed of a plurality of dots and various figures can be drawn. Further, it is also preferable that the dots are formed and arranged as minute pixels that cannot be visually recognized as dots when the image on the image display device is viewed by a normal visual observation method.
Details of the luminescent dopant and host compound that can be used in the present invention will be described later.

(1.2.2) Non-light emitting part and non-light emitting layer The non-light emitting part according to the present invention has a non-light emitting layer. The non-light emitting layer is a layer that does not contain an amount of a light emitting dopant that induces a light emitting phenomenon. The non-light emitting portion or the non-light emitting layer has a role of a bank (embankment) when forming a pixel composed of the light emitting layer. The non-light emitting layer is preferably formed by using a host compound and / or an insulating polymer described later.

In the present invention, when the thickness of the non-light emitting layer of the non-light emitting portion is A and the thickness of the light emitting layer of the light emitting portion is B, the thickness A of the non-light emitting layer of the non-light emitting portion is the light emitting portion. It is characterized in that it is 1.5 times or more thicker than the thickness B of the light emitting layer.
Further, it is preferable to satisfy the following relational expression (1) in that a great effect can be obtained on contrast, uniformity of light emission, and the like.
Relational expression (1): A / B = 1.5 to 5.5

The thickness of the non-light emitting layer is preferably in the range of 25 to 150 nm. On the other hand, the thickness of the light emitting layer is preferably in the range of 15 to 60 nm. The thickness of the non-light emitting layer and the light emitting layer is the distance from the interface between the non-light emitting layer and the hole transport layer (lower layer) to the surface of each layer.
The thickness can be measured using a surface shape measuring device (for example, a stylus type surface shape measuring device (Dectak) manufactured by ULVAC, a small high-speed spectroscopic ellipsometer, or the like.

Further, it is preferable that the molecular weight of the host compound contained in the host layer is 1000 or less from the viewpoint of solubility in a solvent and the like.
Further, it is also preferable that the hole transport layer is provided under the non-light emitting layer in terms of hole transport to the adjacent light emitting layer.

(12.3) Luminescent Dopant and Host Compound The light emitting layer 6a is a layer containing at least a luminescent dopant and preferably a host compound and a luminescent dopant. On the other hand, the non-light emitting layer constituting the non-light emitting portion may be a layer containing a host compound.

As the luminescent dopant, a fluorescent compound and / or a phosphorescent compound can be used. Further, as the fluorescent compound, a thermally activated delayed fluorescent compound can also be used. Details of specific examples of the luminescent dopant will be described later.

The host compound used for the light emitting layer and the non-light emitting layer of the non-light emitting portion according to the present invention is a compound mainly responsible for dispersion of luminescent compounds and charge transfer (carrier) in the light emitting layer, and is used in an organic EL device. The luminescence of itself is practically not observed.

As described above, the non-light emitting layer constituting the non-light emitting portion has a role of a bank (embankment) when forming a pixel composed of the light emitting layer. Therefore, when the host compound is used for the non-light emitting layer, the non-light emitting layer has a role. The host compound is preferably a compound that can play the role of a bank according to the present invention.
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 charge transfer, and it is possible to improve the efficiency of the organic electroluminescence device.
Details of specific examples of the host compound and the like will be described later.

(12.4) Relationship of Each Element in the Basic Configuration of the Organic EL Element 1 In the example shown in FIG. 1A, each component of the organic EL element 1 is provided on the base material 2 and is a base. From the material 2 side, the first electrode 3, the organic functional layer unit 1U made of an organic material, and the second electrode 10 are laminated in this order. A take-out electrode 11 is provided at the end of the first electrode 3. The first electrode 3 and the external power supply (not shown) are electrically connected via the take-out electrode 11. The organic EL element 1 shown in FIG. 1A is configured to take out the generated emitted light from at least the base material 2 side.
As shown in FIG. 1A, the organic functional layer unit 1U includes a non-light emitting unit 7 and a light emitting unit 6, and as shown in FIG. 2, the light emitting unit 6 has a non-light emitting layer. The light emitting layer 6a obtained by melting is formed.

As a specific configuration of the organic EL element 1 shown in FIG. 1, for example, the first electrode 3 functions as an anode (anode) and the second electrode 10 functions as a cathode (cathode). In this case, for example, in the organic functional layer unit 1U, the hole injection layer 4 / hole transport layer 5 / non-light emitting layer 7a / light emitting layer 6a / electron transport layer 8 / electron injection are performed in this order from the first electrode 3 side which is the anode. The layer 9 is laminated. However, the non-light emitting layer 7a according to the present invention is arranged so as to be parallel to the light emitting layer as described above.

Among these organic functional layers, in the present invention, it is an indispensable constituent requirement to have at least a light emitting layer 6a and a non-light emitting layer 7a. The hole injection layer 4 and the hole transport layer 5 may be provided as the hole transport injection layer. Similarly, the electron transport layer 8 and the electron injection layer 9 may be provided as an electron transport injection layer. Further, among these organic functional layer units 1U, for example, the electron injection layer 9 may be made of an inorganic material.

In addition to these layers, the organic functional layer unit 1U may be laminated with a hole blocking layer, an electron blocking layer, or the like, if necessary. Further, the light emitting layer may have a plurality of light emitting layers of each color that generate light emitted in each wavelength region. The intermediate layer may be provided with a function as a hole blocking layer or an electron blocking layer.

Further, the second electrode 10 which is a cathode may also have a laminated structure if necessary. In such a configuration, only the portion where the organic functional layer unit 1U is sandwiched between the first electrode 3 and the second electrode 10 becomes the image display region 1A in the organic EL element 1.

The organic EL element 1 having the above configuration is provided on the base material 2 via a sealing adhesive 13 for the purpose of preventing deterioration of the organic functional layer unit 1U constructed by using an organic material or the like. It is sealed with the sealing base material 14. Further, the first electrode 3 and its take-out electrode 11 and the terminal portion of the second electrode 10 and its take-out electrode 12 are adhered for sealing on the base material 2 in a state of being insulated from each other by the organic functional layer unit 1U. It is provided in a state of being exposed from the agent 13.

(1.3) Method for Forming Light Emitting Part and Non-Light Emitting Part In the present invention, in forming the non-light emitting part and the light emitting part, the non-light emitting layer is formed by an inkjet printing method or a wet process other than the inkjet printing method. It has a step and a step of forming a light emitting layer containing a light emitting dopant by an inkjet printing method, and has a solubility parameter value (SP value) of a solvent of a compound-containing liquid used for forming a non-light emitting layer and a light emitting layer. The difference from the solubility parameter value (SP value) of the solvent of the ink used for formation is preferably 2 or less.

FIG. 2 shows a conceptual diagram of a basic mode of the process of forming the non-light emitting portion and the light emitting portion.
In FIG. 2, after the non-light emitting layer 7a is formed by a wet process other than the inkjet printing method or the inkjet printing method, that is, by some wet process not limited to the inkjet printing method, the non-light emitting layer 7a is formed with a light emitting dopant (Dp). ) Or a droplet of ink of a mixture of a luminescent dopant and a host compound (Dp / Host) is injected onto the non-luminescent layer by an inkjet printing method.

By injecting the ink droplets, the non-light emitting layer is partially dissolved by the solvent contained in the ink, and the luminescent dopant is permeated into the non-light emitting layer to form the non-light emitting layer 7a. And a light emitting layer which is a mixed layer of a light emitting dopant is formed.
FIG. 3 shows a conceptual diagram showing the relationship between the thicknesses of the light emitting layer 6a and the non-light emitting layer 7a of the light emitting portion according to the present invention.

In the present invention, a part of the non-light emitting layer is dissolved to form the light emitting layer in a dot shape, and it is desirable that the method can be patterned. A printing method using a mask with a patterning opening may be used, but a non-contact method is preferable from the viewpoint of less damage to the non-light emitting layer.
Further, the dispenser method and the inkjet printing method are more preferable from the viewpoint of enabling high resolution. The volume of the solution containing the luminescent dopant is 10 μL or less, preferably 100 pL or less.
The size of the dots is preferably in the range of 30 to 300 μm as a circle-equivalent particle size when measured based on an optical micrograph (plan view) taken from the main light emitting surface side of the light emitting layer.

<Wet process>
"Wet process" (also referred to as "wet method") refers to a method or process of forming an object using a liquid substance.
The wet process used in the present invention includes a spin coating method, a casting method, an inkjet printing method, a die coating method, a blade coating method, a roll coating method, a spray coating method, a curtain coating method, and an LB method (Langmuir-Brojet method). And so on.
Among the above methods, a method having high suitability for the roll-to-roll method such as a die coating method, a roll coating method, an inkjet printing (recording) method, and a spray coating method from the viewpoint of easy acquisition of a homogeneous thin film and high productivity. Is preferable. In particular, the inkjet printing (recording) method is preferable. Details of the inkjet printing method will be described later.

(solvent)
The liquid medium for dissolving or dispersing the organic EL material (compound or mixture) according to the present invention is not particularly limited, and the following solvent is used as a solvent for forming the light emitting layer, the host layer and other functional layers. be able to.
The liquid medium for dissolving or dispersing the organic EL material (compound or mixture) according to the present invention is not particularly limited, and for example, halogens such as chloroform, carbon tetrachloride, dichloromethane, 1,2-dichloroethane, dichlorobenzene and dichlorohexanone. System solvents, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, n-propyl methyl ketone, cyclohexanone, aromatic solvents such as benzene, toluene, xylene, mesitylene, cyclohexylbenzene, cyclohexane, decalin, dodecane, etc. Adipose solvent, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, diethyl carbonate and other ester solvents, tetrahydrofuran, dioxane and other ether solvents, dimethylformamide , Amid solvents such as dimethylacetamide, alcohol solvents such as methanol, ethanol, 1-butanol and ethylene glycol, nitrile solvents such as acetonitrile and propionitrile, dimethyl sulfoxide, water or a mixed solution medium thereof and the like. ..

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 viewpoint of the influence of water contained in the solvent, leveling property, wettability to the substrate 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.

The coating liquid used in the wet method may be a solution in which the material forming the organic 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.

Similar to the layer (film) thickness, the viscosity of the coating film can be appropriately selected depending on the function required as the organic functional layer and the solubility or dispersibility of the organic material. Specifically, for example, 0. It can be selected within the range of 3 to 100 mPa · s.

After forming the coating film by the wet method, it is possible to have a drying 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 organic 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 drying time is preferably an appropriate time (for example, at 120 ° C. for 30 minutes) depending on the material such as the solvent used. Under such conditions, drying can be performed quickly.
The vapor pressure (kPa) of each solvent according to the present invention at 1 atm and 25 ° C. can be determined according to the method described below. For example, the lead method of JIS K2258-1: 2009 and the triple expansion method of JIS K2258-2: 2009 can be mentioned. Further, a static method, a boiling point method, an isoteniscope, a gas flow method, and a DSC method, which are known as general methods for measuring vapor pressure, can also be applied. Furthermore, it is also possible to utilize the vapor pressure data described in publicly known documents, for example, "New Edition Solvent Pocket Book" (edited by the Church of Synthetic Organic Chemistry, Ohmsha).

(Solubility parameter value (SP value))
In the method for forming the light emitting portion and the non-light emitting portion according to the present invention, the solubility parameter value (SP value) of the solvent of the compound-containing liquid used for forming the non-light emitting layer and the solubility parameter value of the solvent of the ink used for forming the light emitting layer The difference from (SP value) is preferably 2 or less.

The “solubility parameter value (also referred to as“ SP value ”; Solution parameter)” is a numerical value indicating how easily each other dissolves. The SP value is represented by the attractive force between the molecules, that is, the square root of the cohesive energy density CED (Choice Energy Density).
The CED is the amount of energy required to evaporate 1 mL of the product.
The solubility parameter value (SP value) is defined by the regular solution theory introduced by Hildebrand and serves as a measure of the solubility of a two-component solution.
There are various theories about the calculation method of the SP value, but in the present invention, the method of Fedors generally used is used.

The SP value can be calculated using the following formula (A) by the Fedors method.
SP value (solubility parameter) = (CED value) 1/2 = (E / V) 1/2 ... Equation (A)
In the formula (A)
E is the molecular aggregation energy (cal / mol),
V is the molecular volume (cm ³ / mol) and
When the evaporation energy of the atomic group is Δei and the molar volume is Δvi, they are represented by the following formulas (B) and (C).
E = ΣΔei ・ ・ ・ Equation (B)
V = ΣΔvi ・ ・ ・ Equation (C)

As the data of the calculation method, the evaporation energy Δei and the molar volume Δvi of each atomic group, the data described in "Basic Theory of Adhesion" (written by Minoru Imoto, published by Polymer Publishing Association, Chapter 5) is used. be able to.
In addition, for those for which -CF ₃ units, etc. are not shown, R.M. F. Fedors, Polym. Eng. Sci. 14, 147 (1974) can be referred to.

2. Organic Functional Layers and Electrodes Consisting of Organic EL Devices In the following, the main organic functional layers and the like constituting the organic EL elements of the present invention will be sequentially described.

(2.1) 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 recombine and emit light via excitons, and emit light. The portion to be formed may be in the layer of the light emitting layer or may be 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 point of view
It is preferably adjusted in the range of 2 nm to 1 μm, more preferably in the range of 2 to 200 nm, and even more preferably in the range of 3 to 150 nm.

Before going into a more detailed description of the light emitting layer, a light emitting method and a light emitting material of an organic EL related to the technical idea underlying the present invention will be described.

<< Organic EL light emission method >>
There are two types of emission methods for organic EL: "phosphorescence emission" that emits light when returning from the triplet excited state to the ground state, and "fluorescence emission" that emits light when returning from the singlet excited state to the ground state. be.
When excited by an electric field such as an organic EL element, triplet excitators are generated with a 75% probability and singlet excitors are generated with a 25% probability, so phosphorescence emission is more luminescent than fluorescence emission. It is possible to increase the efficiency and it is an excellent method to realize low power consumption.

Furthermore, in recent years, Adachi et al. Have discovered that by reducing the energy gap between the single-term excited state and the triple-term excited state, triples with lower energy levels due to Joule heat during light emission and / or the environmental temperature at which the light-emitting element is placed. A phenomenon in which inverse intertermic intersection occurs from the term-excited state to the single-term excited state, resulting in nearly 100% fluorescent emission (also referred to as thermally activated delayed fluorescence or thermally excited delayed fluorescence: "TADF": thermally. Activated delayed fluorescence) and fluorescent compounds that enable it have been found (eg, Non-Patent Documents H. Uoyama, et al., Nature, 2012, 492, 234-238, H. Nakanоtani, et al. , Nature Communication, 2014, 5, 4016-4022, etc.).

<< Phosphorescent compound >>
As mentioned above, phosphorus light emission is theoretically three times more advantageous than fluorescence emission in terms of emission efficiency, but energy deactivation (= phosphorus light emission) from the triplet excited state to the singlet ground state is prohibited. Since it is a transition and the intersystem crossing from the singlet excited state to the triplet excited state is also a forbidden transition, its velocity constant is usually small. That is, since the transition is unlikely to occur, the phosphorescence lifetime is extended to the order of milliseconds to seconds, and it is difficult to obtain desired light emission.
However, when a complex using a heavy metal such as iridium or platinum emits light, the rate constant of the forbidden transition increases by three orders of magnitude or more due to the heavy atom effect of the central metal, and depending on the selection of the ligand, 100 It is also possible to obtain a phosphorus photon yield of%.

《Fluorescent compound》
A general fluorescent material does not need to be a heavy metal complex like a phosphorescent material, and is a so-called organic compound composed of a combination of general elements such as carbon, oxygen, nitrogen and hydrogen. In addition, other non-metal elements such as phosphorus, sulfur, and silicon can be used, and complexes of typical metals such as aluminum and zinc can also be used, so that the variety can be said to be almost infinite.
However, since only 25% of excitons can be applied to light emission with a conventional fluorescent compound as described above, high-efficiency light emission such as phosphorescence light emission cannot be expected.

<< Delayed fluorescent compound >>
[Excited triplet-triplet annihilation (TTA) delayed fluorescent compound]
An emission method using delayed fluorescence has emerged to solve the problems of fluorescent compounds. The TTA method originating from the collision between triplet excitons can be described by the following general formula. That is, there is an advantage that a part of triplet excitons, in which exciton energy is conventionally converted only into heat by non-radiation deactivation, can cross the singlet excitons that can contribute to light emission. Even in an actual organic EL element, it is possible to obtain an external extraction quantum efficiency about twice that of a conventional fluorescent light emitting element.
General formula: T * + T * → S * + S (In the formula, T * represents a triplet exciton, S * represents a singlet exciton, and S represents a ground state molecule.)
However, as can be seen from the above equation, since only one singlet exciton that can be used for light emission is generated from the two triplet excitons, it is not possible in principle to obtain 100% internal quantum efficiency by this method.

<< Thermally Activated Delayed Fluorescence (TADF) Compound >>
The TADF method, which is another high-efficiency fluorescent emission, is a method that can solve the problems of TTA.
Fluorescent compounds have the advantage of being able to design an infinite number of molecules as described above. That is, in the molecular design compounds, specifically triplet excited state and the energy level difference between the singlet excited state (hereinafter, appropriately abbreviated as "Delta] E _ST".) Is very close compound present do.
Such compounds, even though in the molecule does not have a heavy atom, reverse intersystem crossing from a triplet excited state is usually not occur because Delta] E _ST is smaller to the singlet excited state occurs. Furthermore, since the rate constant of deactivation (= fluorescence emission) from the singlet excited state to the ground state is extremely large, the triplet excited state itself is thermally deactivated to the ground state (non-radiation deactivation). It is more rhythmically advantageous to return to the ground state while emitting fluorescence via the singlet excited state. Therefore, TADF can theoretically emit 100% fluorescent light.

<Molecular design concepts related to ΔE _ST>
It explained molecular design for reducing the Delta] E _ST.
ΔE in order to reduce the _ST is highest occupied molecular orbital in principle molecules (highest occupied molecular orbital: HOMO) and lowest unoccupied molecular orbital (lowest unoccupied molecular orbital: LUMO) spatial overlap the small to most effects of Is the target.
It is generally known that HOMO is distributed in an electron donating site and LUMO is distributed in an electron attracting site in the electron orbit of a molecule. By introducing an electron donating and electron attracting skeleton into the molecule, HOMO is distributed. And the position where LUMO exists can be moved away.

For example, in Applied Physics Vol. 82, No. 6, 2013 of "Organic Optoelectronics Reaching the Practical Use Stage", electron-withdrawing skeletons such as cyano groups and triazines and electron donations such as carbazole and diphenylamino groups are provided. LUMO and HOMO are localized by introducing a sexual skeleton.
It is also effective to reduce the change in molecular structure between the ground state and triplet excited state of the compound. As a method for reducing the structural change, for example, making the compound rigid is effective. Rigidity described here means that there are few parts in the molecule that can move freely, such as suppressing free rotation in the bond between rings in the molecule and introducing a fused ring with a large π-conjugated surface. means. In particular, it is possible to reduce the structural change in the excited state by making the portion involved in light emission rigid.

(2.1.1) Luminescent Dopant As the luminescent dopant according to the present invention, a fluorescent luminescent compound and a phosphorescent luminescent compound are preferably used. In the present invention, the luminescent dopant is preferably contained in the light emitting layer in the range of 5 to 80% by mass, and particularly preferably in the range of 20 to 40% by mass.

The concentration of the luminescent compound in the light emitting layer can be arbitrarily determined based on the specific luminescent compound used and the requirements of the device.
Further, the luminescent compound used in the present invention may be used in combination of a plurality of types, and may be used in combination of fluorescent compounds having different structures or in combination of a fluorescent compound and a phosphorescent compound. You may. Thereby, an arbitrary emission color can be obtained.

The emission colors of the organic EL element of the present invention and the compound used in the present invention are shown in FIG. It is determined by the color when the result measured by the luminometer CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.
In the present invention, it is also preferable that the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting compounds having different light emitting colors and exhibits white light emission.
The combination of luminescent compounds showing white color is not particularly limited, and examples thereof include a combination of blue and orange and a combination of blue and green and red.
The white color in the organic EL element of the present invention means that the chromaticity in the CIE 1931 color system at ^{1000 cd / m 2} is x = 0.39 ± 0.09 when the 2 degree viewing angle front luminance is measured by the above method. , Y = 0.38 ± 0.08, preferably within the region.

(2.1.1.1) Fluorescent Luminescent Compound As the fluorescent luminescent compound, the above-mentioned specific organic compound may be used, or a known fluorescent luminescent compound or delay used in the light emitting layer of the organic EL element. A compound that emits fluorescence (delayed fluorescence emitting compound) may be appropriately selected and used.

Examples of known fluorescent compounds that can be used in the present invention include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluorantene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron. Examples thereof include complexes, 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.

Examples of compounds that emit delayed fluorescence (delayed fluorescent compounds and thermally activated delayed fluorescence compounds) are International Publication No. 2011/156793, JP2011-213643, JP2010-93181, and Patent 5366106. No., International Publication No. 2013/161437, International Publication No. 2016/158540, and the like can be mentioned, but the present invention is not limited thereto.

As the thermally activated delayed fluorescent compound, compounds having a structure represented by the following general formulas (1) to (6) are preferable.

[In the general formula (1), Ar ^{1 to} Ar ³ each independently represent a substituted or unsubstituted aryl group, and at least one is substituted with a group having a structure represented by the following general formula (2). Represents an aryl group. ]

[In the general formula (2), R ^{1 to} R ⁸ each independently represent a hydrogen atom or a substituent. Z represents O, S, O = C, Ar ^4- N, or a chemical bond. Ar ⁴ represents a substituted or unsubstituted aryl group. Adjacent groups of R ^{1 to} R ⁸ may form a bond with each other or form a ring via a connecting group. ]

[In the general formula ^(3), at least one of R 1 to R ⁵ represents a cyano ^group, at least one of R 1 to R ⁵ is a group having the structure represented by the following general formula (4) , The remaining R ^{1 to} R ⁵ represent hydrogen atoms or substituents. ]

[In the general formula (4), R ^{21 to} R ²⁸ each independently represent a hydrogen atom or a substituent. However, at least one of the following requirements (A) or (B) is satisfied.
Requirement (A): R ²⁵ and R ²⁶ form a single bond.
Requirement (B): R ²⁷ and R ²⁸ represent the atomic groups required to form a substituted or unsubstituted benzene ring. ]

[In the general formula (5), R ¹ and R ² each independently represent a group having a structure represented by the following general formula (6). ]

[In the general formula (6), R ^{1 to} R ⁸ each independently represent a hydrogen atom or a substituent. Z represents O, S, O = C, Ar ^4- N, or a bond. Ar ⁴ represents a substituted or unsubstituted aryl group. Adjacent groups of R ^{1 to} R ⁸ may form a bond with each other or form a ring via a connecting group. ]

The TADF compound is given below as an example, but the present invention is not limited thereto.

Hereinafter, various measuring methods for the TADF compound according to the present invention will be described.

(Electron density distribution)
In the luminescent compound according to the present invention, it is preferable that HOMO and LUMO are substantially separated in the molecule from the viewpoint of reducing ΔEst. The distribution state of these HOMO and LUMO can be obtained from the electron density distribution when the structure is optimized obtained by the molecular orbital calculation.
For the structural optimization and the calculation of the electron density distribution by the molecular orbital calculation of the luminescent compound according to the present invention, software for molecular orbital calculation using B3LYP as a functional and 6-31G (d) as a basis function is used as a calculation method. It can be calculated by using it, and the software is not particularly limited, and it can be calculated in the same manner by using any of them.

In the present invention, Gaussian 09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian, USA was used as the software for calculating the molecular orbital.
Further, "HOMO and LUMO are substantially separated" means that the central parts of the HOMO orbital distribution and the LUMO orbital distribution calculated by the above molecular calculation are separated, and more preferably, the HOMO orbital distribution and the LUMO orbital are separated. It means that the distributions of are almost non-overlapping.

Regarding the separated state of HOMO and LUMO, the time-dependent density functional theory (Time-Dependent DFT) is applied from the structural optimization calculation using B3LYP as the functional and 6-31G (d) as the basis function. It is also possible to calculate the excited state to obtain _{the energies of S 1} and T ₁ (E (S ₁ ) and E (T ₁ ), respectively) and calculate as ΔEst = E (S ₁ ) -E (T _1). Is. The smaller the calculated ΔEst, the more separated HOMO and LUMO are. In the present invention, ΔEst calculated by using the same calculation method as described above is preferably 0.5 eV or less, more preferably 0.2 eV or less, and further preferably 0.1 eV or less.

(Minimum excitation singlet energy S ₁ )
For the lowest excited singlet energy S ₁ luminescent compound according to the present invention is defined by what is calculated in the same manner as the conventional method in the present invention. That is, a compound to be measured is vapor-deposited on a quartz substrate to prepare a sample, and the absorption spectrum (vertical axis: absorbance, horizontal axis: wavelength) of this sample is measured at room temperature (25 ° C.). A tangent line is drawn with respect to the rising edge of the absorption spectrum on the long wavelength side, and the calculation is performed from a predetermined conversion formula based on the wavelength value at the intersection of the tangent line and the horizontal axis.

However, when the luminescent compound used in the present invention has a relatively high cohesiveness of the molecule itself, an error due to cohesion may occur in the measurement of the thin film. Luminescent compound in the present invention that the Stokes shift is relatively small, considering that further structural changes in the excited state and the ground state is small, the lowest excited singlet energy S ₁ according to the present invention, at room temperature (25 ° C.) The peak value of the maximum emission wavelength in the solution state of the luminescent compound was used as an approximate value. Here, as the solvent used, a solvent that does not affect the aggregated state of the luminescent compound, that is, a solvent that is less affected by the solvent effect, for example, a non-polar solvent such as cyclohexane or toluene can be used.

(Measurement of Stokes shift)
The excitation (absorption) spectrum and the emission spectrum of the solution of the luminescent compound (using an appropriate solvent such as dichloromethane or chloroform) are measured with a fluorescence spectrophotometer (for example, RF-5300 type fluorescence spectrometer manufactured by Shimadzu Corporation, manufactured by Hitachi, Ltd.). It can be measured using an F-4500 type fluorescence spectrometer or the like), and the difference between the fluorescence maximum wavelength and the excitation (absorption) maximum wavelength can be obtained as a “Stokes shift”.

(2.1.1.2) Phosphorescent Dopant The phosphorescent dopant used in the present invention is a compound in which light emission from an excited triplet is observed, and specifically, at room temperature (25 ° C.). It is a compound that emits phosphorescence in the above, and is defined as a compound having a phosphorescence quantum yield of 0.01 or more at 25 ° C., and 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-emitting dopant used in the present invention has the above-mentioned phosphorescence quantum yield (0.01 or more) in any of the solvents. It should be achieved.

The phosphorescent dopant can be appropriately selected and used 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. 2009/10991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Application Publication No. 2006/835469, US Patent Application Publication No. 2006 / 0202194, US Patent Application Publication No. 2007/0087321, US Patent Application Publication No. 2005/0244673, Inorg. Chem. 40,1704 (2001), Chem. Mater. 16,2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86,153505 (2005), Chem. Lett. 34,592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42,1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Application Publication No. 2002/0034656, US Pat. No. 7,332,232, USA Publication of Patent Application No. 2009/01087737, Publication of US Patent Application No. 2009/00397776, US Patent No. 6921915, US Patent No. 6687266, US Patent Application Publication No. 2007/0190359, US Patent Application Publication No. 2006/0008670, US Patent Application Publication No. 2009/0158464, US Patent Application Publication No. 2008/0015355, US Patent No. 7250226, US Patent No. 7396598, US Patent Application Publication No. 2006/0263635, US Patent Application Publication No. 2003/0138657, US Patent Application Publication No. 2003/0152802, US Patent No. 70090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18,5119 (2006), Inorg. Chem. 46,4308 (2007), Organometallics 23,3745 (2004), Appl. Phys. Lett. 74,1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/090024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Application Publication No. 2006/0251923, US Patent Application Publication No. 2005/02060441, US Patent No. 73935999 , US Patent No. 7534505, US Patent No. 7445855, US Patent Application Publication No. 2007/0190359, US Patent Application Publication No. 2008/0297033, US Patent No. 7338722, US Patent Application Publication No. 2002 / 0134984, US Patent No. 7279704, US Patent Application Publication No. 2006/098120, US Patent Application Publication No. 2006/103874, International Publication No. 2005/076380, International Publication No. 2010/032663 , International Publication No. 2008140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/1163646, International Publication No. 2012/20327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, US Patent Application Publication No. 2012/228583, US Patent Application Publication No. 2012/212126 Japanese Patent Application Laid-Open No. 2012-069737, Japanese Patent Application Laid-Open No. 2011-181303, Japanese Patent Application Laid-Open No. 2009-114086, Japanese Patent Application Laid-Open No. 2003-81988, Japanese Patent Application Laid-Open No. 2002-302671 and Japanese Patent Application Laid-Open No. 2002-363552 And so on.
Among them, a preferable phosphorescent dopant is an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond is preferable.

(2.1.1.3) Host compound The host compound used for the light emitting layer and the non-light emitting layer of the non-light emitting portion according to the present invention mainly disperses the luminescent compound and transfers charges (carriers) in the light emitting layer. It is a compound responsible for the above, and its own light emission is not substantially observed in the organic EL device.
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 charge transfer, and it is possible to improve the efficiency of the organic electroluminescence device.

From the viewpoint of reverse energy transfer, the host compound preferably has an excitation energy larger than the excitation singlet energy of the luminescent dopant, and further has an excitation triplet energy larger than the excitation triplet energy of the luminescent dopant. More preferred.

From the viewpoint of drive stability, the host compound can exist stably in all active species in the cationic radical state, the anionic radical state, and the excited state, and does not cause chemical changes such as decomposition and addition reaction. It is preferable that the host molecules do not move at the ongstrom level in the layer over time of energization.
The host compound that can be used in the present invention is not particularly limited, and compounds conventionally used in organic EL devices can be used. Typically, carbazole derivatives, triarylamine derivatives, aromatic derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, oligoarylene compounds and the like have a basic skeleton, or carboline derivatives and diazacarbazole derivatives (here). The diazacarbazole derivative refers to a derivative in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is replaced with a nitrogen atom.)

As the known host compound that can be used in the present invention, a compound having a hole transporting ability and an electron transporting ability, preventing a long wavelength of light emission, and having a high Tg (glass transition temperature) is preferable.
Further, in the present invention, conventionally known host compounds 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. Further, by using a plurality of conventionally known compounds, it is possible to mix different luminescences, and thereby an arbitrary luminescence color can be obtained.

Further, the host compound used in the present invention may be a low molecular weight compound, a high molecular weight compound having a repeating unit, or a low molecular weight compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable host compound). Often, one or more such compounds may be used.

When a known host compound is used for the organic EL device of the present invention, specific examples thereof include the compounds described in the following documents, but the present invention is not limited thereto.
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 ,, 2016-178274, US Patent Application Publication No. 2003/01755553, US Patent Application Publication No. 2006 / 0280965, US Patent Application Publication No. 2005/0112407, US Patent Application Publication No. 2009/0017330, US Patent Application Publication No. 2009/0030202, US Patent Application Publication No. 2005/02389919, 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. 2007/0637554, 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, JP-A-2008 -074939, Japanese Patent Application Laid-Open No. 2007-254297, European Patent No. 2034538, International Publication No. 2011/055933, International Publication No. 2012/035853, JP-A-2015-38941, US Special Publication No. License application publication No. 2017/056814.

Among them, as the host compound used in the present invention, a host compound that also dissolves in a non-halogen solvent is preferable, and an ester solvent is more preferable. This is because when a layer is provided under the non-light emitting layer, there is a problem that the lower layer is dissolved if the halogen solvent is used. Further, the molecular weight of the host compound is preferably 1000 or less because it is easily dissolved.

(2.1.1.4) Insulating Polymer The "insulating property" of the insulating polymer that can be used in the present invention means that the electrical resistivity is 1 × 10 ⁶ Ω · m or more, preferably 1 × 10. ^{It is 8} Ω · m or more, more preferably 1 × 10 ¹⁰ Ω · m or more.
It is considered that the leakage current flowing through the light emitting layer can be suppressed when the electrical resistivity of the insulating polymer alone is 1 × 10 ^{6 Ω · m or more.}

The type of the insulating polymer is not particularly limited as long as a non-light emitting layer can be formed. In one embodiment, as the insulating polymer, a polymer having a higher stability and whose main chain is composed of carbon atoms is used.

The insulating polymer is preferably a soluble polymer and preferably exhibits solubility in an aprotic polar solvent so that a light emitting layer containing the insulating polymer can be formed by a coating method. Specifically, the solubility of the insulating polymer in 1 g of N, N-dimethylformamide at 25 ° C. is preferably 0.5 mg or more, more preferably 1.0 mg or more, and more preferably 2.0 mg or more. More preferably.

There are no particular restrictions on the type of insulating polymer, and nonionic polymers such as polystyrene, polymethylmethacrylate, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyvinylpolypyrrolidone, polyethylene glycol, polymethylvinyl ether, and polyisopropylacrylamide. Cationic polymers such as sodium polyacrylate, sodium polystyrene sulfonate, sodium polyisopropylene sulfonate, polynaphthalene sulfonic acid condensate salt, polyethylene iminsantate salt; dimethylaminomethyl (meth) acrylate quaternary salt, dimethyldiallyl Anionic polymers such as ammonium chloride, polyamidine, polyvinyl imidazoline, dicyandiamide-based condensate, epichlorohydrin dimethylamine condensate, polyethyleneimine; dimethylaminoethyl (meth) acrylate quaternary salt acrylic acid copolymer, Hoffman decomposition product of polyacrylamide, etc. Androgynous polymers can be mentioned. Preferably, polystyrene or polymethyl methacrylate is used.
The insulating polymer may contain two or more different repeating units.

The weight average molecular weight of the insulating polymer is not particularly limited, but is preferably 5 × 10 ³ or more, and more preferably 10 × 10 ³ or more. Also, preferably at 1000 × 10 ³ or less, more preferably 400 × 10 ³ or less. It is considered that when the weight average molecular weight is in this range, the diffusion of the luminescent dopant can be appropriately controlled.

<Electronic 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.

In the organic EL device of the present invention, the total thickness of the electron transport layer is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm. ..

Further, in the organic EL element, when the light generated in the light emitting layer is taken out from the electrode, the light taken out directly from the light emitting layer and the light taken out after being reflected by the electrode located at the opposite electrode to the electrode that takes out the light interfere with each other. Is known to cause. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between several nm and several μm.

On the other hand, if the layer thickness of the electron transport layer is increased, the voltage tends to increase. Therefore, especially when the layer thickness is thick, the electron mobility of the electron transport layer ^{is preferably 10-5} cm ² / Vs or more. ..

The material used for the electron transport layer (hereinafter referred to as "electron transport material") may have any of electron injection property, transport property, and hole barrier property, and is a conventionally known compound. Any one can be selected and used.

Examples of the electron transporting material applicable to the electron transporting layer according to the present invention include nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are replaced with nitrogen atoms). , Ppyridine derivative, pyrimidine derivative, pyrazine derivative, pyridazine derivative, triazine derivative, quinoline derivative, quinoxaline derivative, phenanthroline derivative, azatriphenylene derivative, oxazole derivative, thiazole derivative, oxadiazole derivative, thiadiazol derivative, triazole derivative, Benzimidazole derivative, benzoxazole derivative, benzthiazole derivative, etc.), dibenzofuran derivative, azadibenzofuran derivative (one or more carbon atoms constituting the dibenzofuran ring replaced with nitrogen atom), dibenzothiophene derivative, azadibenzothiophene derivative (One or more carbon atoms constituting the dibenzothiophene ring are substituted with nitrogen atoms), silol derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.) and the like.

Further, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, tris (8-quinolinol) aluminum (abbreviation: 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 (abbreviation: Znq), etc., and these. A metal complex in which the central metal of the metal complex of No. 1 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, a distyrylpyrazine derivative, which is an organic functional material applied to a light emitting layer described later, can also be used as an electron transport material, and is n-type-Si or n-type like the hole injection layer and the hole transport layer. -Inorganic semiconductors such as SiC can also be used as electron transport materials.

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 according to the present invention, the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich). 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 known and preferable electron transporting materials 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 Pat. No. 7,964,293, 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. 2007/086552, 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, JP-A-2010-251675, JP-A-2009-209133, JP-A-2009. -124114, 2008-277810, 2006-156445, 2005-340122, 2003-45662, 2003-31367, 2003-282270. Examples of the compounds described in Japanese Patent Application Laid-Open No. 2012/115034 and the like can be mentioned.

More preferable electron transporting materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, azadibenzofuran derivatives, dibenzothiophene derivatives, azadibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives. , And compounds made by combining these.
A preferable compound as a compound used for the electron transport layer of the organic EL device of the present invention is represented by the following general formula (7).

In the general formula (7), X represents an oxygen atom or a sulfur atom. X _{1 to} X ₁₂ independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a terphenyl ring, a naphthyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. Or L ₁ is a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ may be a part of the condensed ring. The substituent used in the general formula (7) is not limited, and is, for example, an alkyl group (for example, a methyl group, an ethyl group, a trifluoromethyl group, an isopropyl group, etc.), an aryl group (for example, a phenyl group). Etc.), heteroaryl group (eg, pyridyl group, carbazolyl group, etc.), halogen atom (eg, fluorine atom, etc.), cyano group, or alkyl fluoride group, and those used in the exemplary compounds described below are also included. preferable.

The R ₁ is a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, an azadibenfuran ring, an azadibenzothiophene ring, an azacarbazole ring, a quinazoline ring, a quinoxaline ring, a quinoline ring, an isoquinoline ring, a benzoquinoline ring, a benzoisoquinoline ring, and an indole. It is preferable to represent a substituent containing a ring, an indazole ring, an imidazole ring, a benzimidazole ring, a benztriazole ring, a pyrazole ring, a triazole ring, an oxazole ring, a thiazole ring or a carbazole ring.

Further, in the general formula (7), X ₈ and X ₁₂ represent a nitrogen atom and X _{9 to} X ₁₁ represent a CR ₁ , or X ₈ and X ₁₁ represent a nitrogen atom, and X ₉ and X It is preferred that ₁₀ and X ₁₂ represent CR ₁ or that X ₈ and X ₁₀ represent a nitrogen atom and X ₉ , X ₁₁ and X ₁₂ represent CR _1.

The compound having the structure represented by the general formula (7) preferably has the structure represented by the following general formula (8).

In the general formula (8), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X _{1 to} X ₁₀ and X _{13 to} X ₁₆ independently _{represent CR 1} or a nitrogen atom, respectively. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a naphthyl ring, a terphenyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. L ₁ is either a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₀ and X _{13 to} X ₁₆ may be a part of the fused ring, respectively. As the substituent used in the general formula (8), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (8) is preferably the same as that in the general formula (7).

A specific example of L ₁ is shown below, but it is an example and is not limited thereto.

Specific examples of the compound represented by the general formula (7) or (8) are shown below.

Further, the compound having the structure represented by the general formula (7) is preferably a compound having the structure represented by the following general formula (9).

In the above general formula (9), X represents an oxygen atom or a sulfur atom. X ₁ , X ₂ , X _{4 to} X ₁₂ and X _{17 to} X ₂₁ each independently _{represent a CR 1} or nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . One of X ₈ and X ₁₀ represents a nitrogen atom and the other represents CR ₁ , or one of X ₁₇ and X ₁₉ represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ and L ₂ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring, dibenzofuran ring. , Dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indol ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. Represents. L ₁ and L _2, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ and L ₂ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{17 to} X ₂₁ may be a part of the condensed ring.

As the substituent used in the general formula (9), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (9) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L ₂ include the same as the specific example of L ₁ given in the general formula (7).

Further, in the general formula (9), X ₈ and X ₁₂ represent a nitrogen atom and X _{9 to} X ₁₁ represent CR ₁ , or X ₈ and X ₁₁ represent a nitrogen atom, and X ₉ and X ₁₀ and X ₁₂ represent CR ₁ , or X ₈ and X ₁₀ represent nitrogen atoms, X ₉ , X ₁₁ and X ₁₂ represent CR ₁ , and / or X ₁₇ and X ₂₁ represent nitrogen. X _{18 to} X ₂₀ represent CR ₁ , or X ₁₇ and X ₂₀ represent nitrogen atoms, and X ₁₈ , X ₁₉ and X ₂₁ represent CR ₁ , or X ₁₇ and X. It is preferred that ₁₉ represents a nitrogen atom and X ₁₈ , X ₂₀ and X ₂₁ represent CR _1.

Further, the compound having the structure represented by the general formula (9) preferably has the structure represented by the following general formula (10).

In the above general formula (10), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₂ , X ₁₇ , X ₁₈ , and X _{22 to} X ₂₉ each independently _{represent a CR 1} or nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ , L ₂ , and L ₃ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. Represents a linking group of. L _1, is _{L 2,} L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (10), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (10) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (7).

Further, in the general formula (10) _{, at least one of X 8 to} X ₁₂ represents a nitrogen atom and the rest represents CR ₁ , and / or at least one of _{X 25 to} X _{29 represents nitrogen.} It is preferred that it represents an atom and the rest represents CR _1.

Further, the compound having the structure represented by the general formula (8) is preferably a compound having the structure represented by the following general formula (11).

In the above general formula (11), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X _{1 to} X ₁₀ and X _{13 to} X ₁₆ independently _{represent CR 1} or a nitrogen atom, respectively. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 3 ≦ m1 + m2 ≦ 4.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a naphthyl ring, a terphenyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. ..

Or L ₁ is a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ may form a fused ring. Further, the _{ring containing X 1 to} X ₇ or the ring containing X _{8 to} X ₁₀ and X _{13 to} X ₁₆ may be a part of the fused ring, respectively.

The substituent used in the general formula (11) is preferably the same as that in the general formula (7). _{The R 1} used in the general formula (11) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L _{1 include the same specific examples of L 1} given in the general formula (7).

Further, the compound having the structure represented by the general formula (10) is preferably a compound having the structure represented by the following general formula (12).

In the above general formula (12), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₂ and X ₁₇ , X ₁₈ , and X _{21 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 3 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is _{L 2,} L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (12), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (12) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (7).

Further, in the general formula (12) _{, at least one of X 8 to} X ₁₂ represents a nitrogen atom and the rest represents CR ₁ , or at least one of _{X 25 to} X _{29 represents a nitrogen atom.} It is preferable that the rest represents CR _1.

Further, the compound having the structure represented by the general formula (8) is preferably a compound having the structure represented by the following general formula (13).

In the general formula (13), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₀ , X _{13 to} X ₁₈ , and X _{21 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 2 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is _{L 2,} L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (13), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (13) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (7).

Further, in the general formula (13), it is preferable that _{at least one of X 25 to} X ₂₉ represents a nitrogen atom and the rest represents CR _1.

Further, the compound having the structure represented by the general formula (10) is preferably a compound having the structure represented by the following general formula (14).

In the above general formula (14), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₀ , X _{13 to} X ₁₈ , and X _{21 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 2 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is _{L 2,} L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group. L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 25 to} X ₂₉ may be a part of the fused ring.

As the substituent used in the general formula (14), the same group as in the general formula (7) is preferable. _{The R 1} used in the general formula (14) is preferably the same as that in the general formula (7). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (7).

Further, in the general formula (14), it is preferable that _{at least one of X 25 to} X ₂₉ represents a nitrogen atom and the rest represents CR _1.

Examples of the compounds represented by the general formulas (9) to (14) include the following compounds M-360 to M-436.

Examples of other compounds applicable to the electron transport layer of the organic EL device of the present invention include compounds 1 to 213 described in Japanese Patent No. 5604848 and compounds 1 to 264 described in Japanese Patent No. 5589251. , Etc. are also preferable.

The electron transport layer according to the present invention is formed by thinning an ink composition containing at least an organic functional material or the like by a known method such as a spin coating method, a casting method, a gravure coating method, or an inkjet printing method. Can be formed with.

(Electron injection layer)
The electron injection layer is a layer provided between the cathode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness, and when the cathode is composed of the light-transmitting electrode according to the present invention. Is provided adjacent to the light-transmitting electrode, and is provided in "Organic EL Element and Its Industrial Frontline (November 30, 1998, published by NTS Co., Ltd.)", Volume 2, Chapter 2, " It is described in detail in "Electrode Material" (pages 123-166).

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, and alkali metal halide layers such as magnesium fluoride and calcium fluoride. Examples thereof include an alkaline earth metal compound layer, a metal oxide typified by molybdenum oxide and aluminum oxide, and a metal complex typified by lithium 8-hydroxyquinolate (Liq). When the light-transmitting electrode in the present invention is a cathode, an organic material such as a metal complex is particularly preferably used. The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 1 nm to 10 μm, although it depends on the constituent materials.

<Hole transport layer>
The "hole transport layer" is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer also have a function of a hole transport layer. The hole transport layer may be provided as a single layer or a plurality of layers.

The hole transporting material has either injection or transport of holes or an electron barrier property, and may be either an organic substance or an inorganic substance. For example, triazole derivatives, oxaziazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stillben derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers and thiophene oligomers.

As the hole transporting material, the above-mentioned compounds can be used, but porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds can be used, and in particular, aromatic tertiary amine compounds are used. Is preferable.

Typical examples of aromatic tertiary amine compounds and styrylamine compounds are N, N, N', N'-tetraphenyl-4,4'-diaminophenyl, N, N'-diphenyl-N, N'-. Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1 -Bis (4-di-p-tolylaminophenyl) cyclohexane, N, N, N', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis (4-di-p) -Trillaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) Quadriphenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4'-[4- (di-p-tolylamino) styryl] stilben, 4-N, N Examples thereof include −diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostillbenzene and N-phenylcarbazole.

The hole transporting layer uses the above hole transporting material, for example, a printing method including a vacuum deposition method, a spin coating method, a casting method, a clavier coating method, an inkjet printing method, and an LB method (Langmuir Bloodget method). Although it can be formed by thinning by a known method such as, in the present invention, it is preferable to apply a wet coating method such as a pin coating method, a casting method, a Clavier coating method, or an inkjet printing method. The thickness of the hole transport layer is not particularly limited, but is usually in the range of about 5 nm to 5 μm, preferably in the range of 5 to 200 nm. The hole transport layer may have a one-layer structure composed of one or more of the above materials.

Further, the p property can be enhanced by doping the material of the hole transport layer with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, and J. Am. Apple. Phys. , 95, 5773 (2004) and the like.

As described above, it is preferable to increase the p property of the hole transport layer because a device having lower power consumption can be manufactured.

<Hole injection layer>
The hole injection layer is a layer that is arranged adjacent to the anode, which is one of the electrodes, in order to reduce the driving voltage and improve the emission brightness. It is described in detail in Chapter 2 "Electrode Materials" (pages 123-166) of Volume 2 of "NTS".

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 , Porphyrin derivative, phthalocyanine derivative, oxazole derivative, oxadiazole derivative, triazole derivative, imidazole derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, hydrazone derivative, stillben derivative, polyarylalkane derivative, triarylamine derivative, carbazole derivative, Indrocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polymer materials or oligomers with polyvinylcarbazole and aromatic amines introduced into the main and side chains, polysilanes, and conductivity. Examples thereof include polymers or oligomers (for example, PEDOT (polyethylene dioxythiophene): PSS (polystyrene sulfonic acid), aniline-based copolymers, polyaniline, polythiophene, etc.).

Examples of the triarylamine derivative include a benzidine type represented by 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: α-NPD) and 4,4', 4 ". -Tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine) (abbreviation: MTDATA) typified by starburst type, triarylamine compounds having fluorene or anthracene in the linking core, etc. Be done.

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.

<Blocking layer>
Examples of the blocking layer include a hole blocking layer and an electron blocking layer, which are layers provided as needed in addition to the constituent layers of the carrier transport function layer unit 3 described above. For example, it is described in JP-A-11-204258, No. 11-204359, and page 237 of "Organic EL Element and Its Industrialization Frontline (November 30, 1998, published by NTS Co., Ltd.)". Examples include a hole blocking (hole block) layer.

The "hole blocking layer" has a function of an electron transporting layer in a broad sense. The hole blocking layer is made of a hole blocking material having a function of transporting electrons and a significantly small ability to transport holes, and recombination of electrons and holes by blocking holes while transporting electrons. The probability can be improved. In addition, the structure of the electron transport layer can be used as a hole blocking layer, if necessary. The hole blocking layer is preferably provided adjacent to the light emitting layer.

On the other hand, the "electron blocking layer" has a function of a hole transporting layer in a broad sense. The electron blocking layer is made of a material that has a function of transporting holes and has a significantly small ability to transport electrons, and improves the recombination probability of electrons and holes by blocking electrons while transporting holes. Can be made to. In addition, the structure of the hole transport layer can be used as an electron blocking layer, if necessary. The layer thickness of the hole blocking layer applied to the present invention is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.

〔Base material〕
The base material (2) applicable to the organic EL element (1) is not particularly limited, and examples thereof include types such as glass and resin base materials, preferably imparting flexibility to the organic EL element. It is a flexible resin base material from the viewpoint of being able to be used.

Examples of the resin material constituting the flexible resin base material applicable to the present invention include polyesters such as polyethylene terephthalate (abbreviation: PET) and polyethylene naphthalate (abbreviation: PEN), polyethylene, polypropylene, cellophane, and the like. Cellulous esters such as cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP), cellulose acetate phthalate, cellulose nitrate and their derivatives, polyvinylidene chloride, polyvinyl chloride. Alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, polyether ketone, polyimide, polyether sulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, Polyether ketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylates, cycloolefin resins such as Arton (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals). Can be mentioned.

Among these resin substrates, films such as polyethylene terephthalate (abbreviation: PET), polybutylene terephthalate, polyethylene naphthalate (abbreviation: PEN), and polycarbonate (abbreviation: PC) are flexible in terms of cost and availability. It is preferably used as a resin base material having.

In the present invention, the thickness of the resin base material can be in the range of 3 to 200 μm, preferably in the range of 10 to 100 μm, and more preferably in the range of 20 to 50 μm.

The base material according to the present invention can also be suitably used as a sealing member (transparent base material) for an organic EL element. Further, the resin base material may be an unstretched film or a stretched film.

The resin base material applicable to the present invention can be produced by a conventionally known general film forming method. For example, by melting the resin as a material with an extruder, extruding it with an annular die or a T die, and quenching it, it is possible to produce an unstretched resin base material that is substantially amorphous and not oriented. Further, the unstretched resin base material is subjected to a known method such as uniaxial stretching, tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, tubular simultaneous biaxial stretching, etc., to convey the resin base material in the transport direction (vertical direction). , MD direction), or in the direction perpendicular to the transport direction of the resin base material (horizontal axis direction, TD direction), the stretched resin base material can be produced. In this case, the draw ratio can be appropriately selected according to the resin used as the raw material of the resin base material, but is preferably in the range of 2 to 10 times in the vertical axis direction and the horizontal axis direction, respectively.

Examples of the glass substrate which is a light-transmitting substrate applicable to the present invention include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, and barium borosilicate glass. , Glass and the like.

〔anode〕
The anode constituting the organic EL element is preferably composed of an oxide semiconductor or a thin metal or alloy, and for example, a metal such as Ag or Au or an alloy containing a metal as a main component, CuI, Alternatively, oxide semiconductors such as indium-tin composite oxides (ITO), SnO ₂ and ZnO can be mentioned.

When the anode is composed of silver as a main component, the purity of silver is preferably 99% or more. Further, palladium (Pd), copper (Cu), gold (Au) and the like may be added to ensure the stability of silver.

When the anode is composed of silver as a main component, it may be formed of silver alone or may be composed of an alloy containing silver (Ag). Examples of such alloys include silver-magnesium (Ag-Mg), silver-copper (Ag-Cu), silver-palladium (Ag-Pd), silver-palladium-copper (Ag-Pd-Cu), and silver. -Indium (Ag-In) and the like can be mentioned.

Among the constituent materials constituting the anode, the anode constituting the organic EL device according to the present invention is composed mainly of indium tin oxide composite oxide (ITO) or silver and has a thickness of 2 to 20 nm. It is preferable that the anode has a light transmittance within the range of, and more preferably the thickness is within the range of 4 to 12 nm. When the thickness is 20 nm or less, the absorption component and the reflection component of the anode having light transmittance are suppressed to a low level, and a high light transmittance is maintained, which is preferable.

The layer composed mainly of indium-tin composite oxide (ITO) or silver in the present invention means that the content of ITO or silver in the anode is 60% by mass or more, preferably. It is 80% by mass or more, more preferably 90% by mass or more, and particularly preferably the content of ITO or silver is 98% by mass or more. Further, the "light transmittance" of the light-transmitting anode according to the present invention means that the light transmittance at a wavelength of 550 nm is 50% or more.

The light-transmitting anode may have a structure in which layers composed of ITO or silver as a main component are divided into a plurality of layers and laminated, if necessary.

Further, in the present invention, when the anode is a light-transmitting anode composed of silver as a main component, the lower part thereof is formed from the viewpoint of enhancing the uniformity of the silver film of the light-transmitting anode. A base layer can be provided on the surface. The base layer is not particularly limited, but is preferably a layer containing an organic compound having a nitrogen atom or a sulfur atom, and a method of forming a light-transmitting anode on the base layer is preferable. be.

Further, the extraction electrode (10) of the first electrode according to the present invention is formed of the same material in the form of extending the first electrode. In the present invention, the distinction between the first electrode (3) and the extraction electrode (10) is that the electrode constituting the light emitting region is defined as the first electrode (3), and the other electrode connected to the conductive member is extracted. It is defined as the electrode (10).

〔cathode〕
The cathode is an electrode film that functions to supply electrons to the organic functional layer group and the light emitting layer, and a metal, an alloy, an organic or inorganic conductive compound, or a mixture thereof is used. Specifically, when a dry forming method such as a vapor deposition method is used, gold, aluminum, silver, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, ittrium / silver mixture, magnesium / aluminum mixture, magnesium / Examples thereof include indium mixtures, indium, lithium / aluminum mixtures, rare earth metals, oxide semiconductors such as _{ITO, ZnO, TiO 2} and SnO _2.

When formed by a wet coating method, a pin coating method or casting is performed using a composite (PEDOT: PSS) of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid, silver nanoink, or the like. It can be formed by a method, a clavier coating method, an inkjet printing method, or the like.

The cathode can be produced by forming a thin film of these conductive materials by a method such as vapor deposition or sputtering. The sheet resistance as the second electrode is several hundred Ω / sq. The following is preferable, and the film thickness is usually selected in the range of 5 nm to 5 μm, preferably 5 to 200 nm.

In the case of the double-sided light emitting type in which the organic EL element also extracts the emitted light L from the cathode side, a cathode having good light transmission may be selected and configured.

[Sealing member]
Examples of the sealing means used for sealing the organic EL element include a method of bonding the flexible sealing member, the cathode and the transparent base material with a sealing 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 thin film glass plate, a polymer plate, a film, and a metal film (metal foil) having flexibility. 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 film include one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium and tantalum.

In the present invention, a polymer film and a metal film can be preferably used as the sealing member from the viewpoint that the organic EL element can be thinned. Further, the polymer film has a water vapor transmission rate of 1 × 10 ^-3 g / m ^2. preferably 24h or less, and further, the oxygen permeability measured in compliance with the method provided in JIS K 7126-1987 ^{is, 1 × 10 -3 mL / m} 2 · 24h · atm (1atm is 1.01325 × 10 ⁵ a Pa) equal to or lower than a temperature of 25 ± 0.5 ° C., water vapor permeability at a relative humidity of 90 ± 2% RH is preferably not more than ^{1 × 10 -3 g / m 2} · 24h.

Examples of the sealing adhesive include acrylic acid-based oligomers, photocurable and thermosetting adhesives having a reactive vinyl group of methacrylic acid-based oligomers, and moisture-curable adhesives such as 2-cyanoacrylic acid ester. Can be mentioned. 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.

《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 organic functional layer sandwiched in order to increase the mechanical strength of the device. 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 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 only about 15 to 20% of the light generated in the light emitting layer is emitted. It is generally said that it cannot 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). 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 grating between layers of a substrate, a transparent electrode layer or a light emitting layer (including between the substrate and the outside world) ( 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 and 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 one of the layers 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 in any of the layers or in the medium (inside the transparent substrate or in the transparent electrode), but it is preferably in the vicinity of the 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 of 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, a specific direction, 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 occurs 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 pitch change. 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.

3. 3. Method for Manufacturing Organic EL Element The method for manufacturing an organic electroluminescence element of the present invention is a method for manufacturing an organic electroluminescence element for manufacturing the organic electroluminescence element, and in forming the non-light emitting portion and the light emitting portion, the above-mentioned method. The non-light emitting layer has a step of forming the non-light emitting layer by a wet process other than the inkjet printing method or the inkjet printing method, and a step of forming the light emitting layer containing a light emitting dopant by the inkjet printing method. The difference between the solubility parameter value of the solvent of the compound-containing liquid used for forming the light emitting layer and the solubility parameter value of the solvent of the ink used for forming the light emitting layer is 2 or less.

(3.1) Method for Manufacturing Organic EL Element by Inkjet Printing Method FIG. 4 is a conceptual diagram showing a method for manufacturing an organic EL element by the inkjet printing method.
FIG. 4A is a schematic view showing an example of a single-pass type (line head type) inkjet printing apparatus applicable to the method for manufacturing an organic EL element of the present invention. In FIG. 4A, 100 is a line head type head unit, and an ink containing an ink having a different hue (for example, a compound that emits red (R), green (G), and blue (B) colors). ) Are ejected from the heads 102 to 104, and the nozzle pitch of each head is preferably about 360 dpi. The dpi in the present invention represents the number of dots per 2.54 cm.
The base material 2 is fed out from the transport mechanism 101 in the direction of the arrow in a state of being laminated in a roll shape.

FIG. 4B is a bottom view showing the arrangement of nozzles at the bottom of each head. As shown in FIG. 4B, the head 102, the head 103, and the nozzles N of the head 104 have a staggered arrangement shifted by half a pitch, respectively. With such a head configuration, a more detailed image can be formed.

FIG. 4C is a schematic view showing an example of the head unit configuration. When a wide base material 2 is used, it is also preferable to use a head unit HU in which a plurality of head Hs are arranged in a staggered arrangement so as to cover the entire width of the base material 2.

4. Others (4.1) Other configurations of organic EL elements For other outlines of the configurations of organic EL elements applicable to the present invention, for example, Japanese Patent Application Laid-Open No. 2013-157634, Japanese Patent Application Laid-Open No. 2013-168552, Kai 2013-177361, JP2013-187911, JP2013-191644, JP2013-191804, JP2013-225678, JP2013-235994, JP2013 -2432334, 2013-243236, 2013-242366, 2013-243371, 2013-245179, 2014-003249, 2014-003299 Examples thereof include the configurations described in JP-A-2014-030910, JP-A-2014-017493, JP-A-2014-017494, and the like.

Specific examples of the tandem type 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. 6107734, US Pat. No. 6,337,492, 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, 2011-96679, 2005-340187, 47112424, 349661, 3884564, 4213169, 2010-192719 Japanese Patent Application Laid-Open No. 2009-07629, 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. 2005/009087, Examples thereof include the element configurations and constituent materials described in International Publication No. 2005/094130, but the present invention is not limited thereto.

(4.2) Application of Organic EL Element According to the Present Invention The organic EL element according to 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, interior lighting), a backlight for a clock or a liquid crystal, a signboard advertisement, a traffic light, 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.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

[Example 1]
<< Fabrication of organic EL element >>
[Manufacturing of organic EL element 1]
[1] Formation of Anode As an anode, a substrate (NA45 manufactured by NH Techno Glass) in which ITO (indium tin oxide) is formed into a film having a thickness of 100 nm is prepared on a glass substrate of 100 mm × 100 mm × 1.1 mm. , Patterning was performed on the substrate. Then, the substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and further subjected to UV ozone cleaning for 5 minutes.

[2] Formation of light emitting part and non-light emitting part
[2.1] the forming the ITO substrate of the non-light-emitting layer (host layer) was transferred under nitrogen, a host compound (Host-1) 90 mg of 500rpm and a solution of propylene glycol monomethyl acetate 3 ml (PGMA _C), Under the condition of 120 seconds, a film was formed (thickness 140 nm) by a spin coating method, and heated and dried at 120 ° C. for 30 minutes to prepare a non-emissive layer (host layer).

[2.2] Formation of light emitting layer of light emitting part Next, using an ink composition for forming a light emitting layer having the following composition, using a piezo type inkjet printer head "KM1024i" manufactured by Konica Minolta, organic by an inkjet printing method. According to the method for manufacturing an EL element, the ink was injected onto the host layer at 25 ° C. and then dried at 120 ° C. for 30 minutes to form a light emitting layer.
After discharging injected phosphorescent dopant Dp-1, the luminescent by propylene glycol monomethyl acetate dopant layer composition (PGMA _C) host layer is partially dissolved, emitting a host compound near the bottom of the dissolved portion A mixed layer of sex dopants, that is, a light emitting layer, was formed. It was heated and dried at 120 ° C. for 30 minutes to prepare a light emitting layer.
The thickness of the light emitting layer was 16 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 130 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 8.4.

(Composition of luminescent dopant-containing liquid)
Phosphorescent Dopant Dp-1 0.72 parts by mass Propylene glycol monomethyl acetate (PGMAc) 100 parts by mass

[2.3] Formation of Electron Transport Layer Subsequently, using an ink composition for forming an electron transport layer having the following composition, using a piezo inkjet printer head "KM1024i" manufactured by Konica Minolta, organic by an inkjet printing method. According to the method for producing an EL element, an electron transport layer was formed by injecting the ink onto a light emitting layer at 25 ° C. and drying at 120 ° C. for 30 minutes under the condition that the layer thickness after drying was 30 nm.

<Ink composition for forming an electron transport layer>
Electron-transporting compound M-33 0.3 parts by mass 2,2,3,3-tetrafluoro-1-propanol (TFPO) 100 parts by mass

[2.4] Formation of electron injection layer and cathode Subsequently, the substrate was attached to a vacuum vapor deposition apparatus without exposure to the atmosphere. In addition, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride, respectively, was attached to a vacuum vapor deposition apparatus, the vacuum tank ^{was depressurized to 4 × 10-5} Pa, and then the boat was energized and heated. Sodium fluoride was deposited on the electron transport layer at 0.02 nm / sec to form a thin film having a layer thickness of 1 nm, and then potassium fluoride was similarly deposited on the thin film at 0.02 nm / sec. An electron-injected layer having a layer thickness of 1.5 nm was provided.

Subsequently, aluminum was vapor-deposited on the electron injection layer to provide a cathode having a thickness of 100 nm.

[2.5] Sealing and Fabrication of Organic EL Element 1 Subsequently, a sealing member was adhered using a commercially available roll laminating apparatus to fabricate the organic EL element 1.

[Example 2]
[Manufacturing of organic EL element 2]
In the method for producing the organic EL element 1, the same is true except that when the light emitting layer of the light emitting portion is formed, a mixed solution of the following host compound and a phosphorescent dopant is used instead of the light emitting dopant-containing liquid. The organic EL element 2 was produced according to the method.
The thickness of the light emitting layer was 33 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 125 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 3.8.

(Mixed solution of host compound and phosphorescent dopant)
Host compound: Host-1 2.3 parts by mass Phosphorescent dopant Dp-1 0.7 parts by mass Propylene glycol monomethyl acetate (PGMAc) 100 parts by mass

[Example 3]
[Manufacturing of organic EL element 3]
In the method for producing the organic EL element 2, the organic EL element 3 was produced according to the same method except that the concentration of the host compound was changed to make the thickness of the non-light emitting layer as shown in Table I.
The thickness of the light emitting layer was 13 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 65 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 5.2.

[Example 4]
[Manufacturing of organic EL element 4]
In the method for producing the organic EL element 2, the organic EL element 4 was produced according to the same method except that the concentration of the host compound was changed to make the thickness of the non-light emitting layer as shown in Table I.
The thickness of the light emitting layer was 54 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 150 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 2.8.

[Example 5]
[Manufacturing of organic EL element 5]
In the method for producing the organic EL element 2, the organic EL element 5 was produced in the same manner except that the hole transport layer was provided under the non-light emitting layer (host layer).
<Formation of hole transport layer>
An ink composition for forming a hole transport layer having the following composition is used for the anode, and a piezo type inkjet printer head "KM1024i" manufactured by Konica Minolta Co., Ltd. is used, according to a method for manufacturing an organic EL element by an inkjet printing method. After injection at ° C. under the condition that the layer thickness after drying was 20 nm, the ink was dried at 120 ° C. for 30 minutes to form a hole transport layer.
<Ink composition for forming a hole transport layer>
Hole transport material HT (weight average molecular weight Mw = 80000) 2.5 parts by mass Tetralin 500 parts by mass

[Example 6]
[Manufacturing of organic EL element 6]
In the method for producing the organic EL element 2, the organic EL element 6 was produced in the same manner except that the solvent of the non-light emitting layer (host layer) was changed to npropyl acetate.

[Example 7]
[Manufacturing of organic EL element 7]
In the method for producing the organic EL element 2, the organic EL element 6 was produced in the same manner except that the solvent of the mixed solution of the host compound and the phosphorescent dopant was changed to tetralin.

[Example 8]
[Manufacturing of organic EL element 8]
In the method for producing the organic EL element 2, the organic EL element 8 was produced in the same manner except that the solvent of the non-light emitting layer (host layer) was changed to cyclohexanol.

[Example 9]
[Manufacturing of organic EL element 9]
In the method for producing the organic EL element 2, the organic EL element 9 was produced in the same manner except that the material of the host layer was changed to Host-2.

[Example 10]
[Manufacturing of organic EL element 10]
In the method for producing the organic EL element 2, the organic EL element 2 was produced in the same manner as the organic EL element 2 except that a dispenser method was used instead of the inkjet printing method when forming the light emitting layer.

[Example 11]
[Manufacturing of organic EL element 11]
In the method for producing the organic EL element 2, the organic EL element 11 was produced in the same manner except that the material of the host layer was changed to polystyrene (molecular weight 260,000).
The thickness of the light emitting layer was 29 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 59 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 2.0.

[Comparative Example 1]
[Manufacturing of organic EL element 12]
In the method for producing the organic EL element 2, the organic EL element 12 was produced according to the same method except that the concentration of the host compound was changed to make the thickness of the non-light emitting layer as shown in Table I.
The thickness of the light emitting layer was 19 nm. Further, when the light emitting layer is formed, the thickness of the host layer portion (that is, the non-light emitting layer of the non-light emitting portion) remaining undissolved by the solvent is 25 nm, and the thickness of the host layer / the thickness of the light emitting layer. The value of the solvent ratio was 1.3.

[Comparative Example 2]
[Manufacturing of organic EL element 13]
In the method for producing the organic EL element 5, the organic EL element 13 was produced according to the same method except that the host layer, which is a non-light emitting layer, was not provided.

[evaluation]
The following evaluations were performed on the organic EL elements 1 to 13.
(Evaluation of dot diameter)
The dot diameter was measured using a camera attached to the printer.
Relative evaluation was performed based on the following criteria.

⊚: 120 μ or less 〇: 120 μ or more to 140 μ
Δ: Over 140 μ to 160 μ
×: Over 160 μ

(Evaluation of external extraction efficiency (EQE))
Each organic EL element is energized under constant current conditions of room temperature (about 23 ° C.) and ^2.5 mA / cm 2, and the emission brightness (L0) (cd / m ² ) immediately after the start of emission is measured to measure the external emission brightness (L0) (cd / m 2). The extraction quantum efficiency (EQE) was calculated.

Here, the emission brightness is measured using a spectral radiance meter CS-2000 (manufactured by Konica Minolta Co., Ltd.), and the external extraction quantum efficiency is obtained by obtaining a relative EQE with the organic EL element 8 as 100, and the following The external extraction quantum efficiency (EQE) was evaluated according to the evaluation rank.
⊚: 120 or more 〇: 105 or more and less than 120 Δ: 95 or more and less than 105 ×: less than 95

(Evaluation of element life)
^{Each organic EL element was continuously driven with a constant current giving 1000 cd / m 2} as the initial brightness under an atmosphere of dry nitrogen at 23 ° C., and the time required for the brightness to be halved (500 cd / m ^{2) was measured.} This was used as an index of device life as a half life time (LT50). The half-life time (LT50) was expressed as a relative value with the measured value of the organic EL element 8 as 100.
Evaluation was made based on the following criteria.
⊚: 120 or more 〇: 105 or more and less than 120 Δ: 95 or more and less than 105 ×: less than 95

(Evaluation of contrast)
Under normal laboratory lighting, the element is placed on a predetermined table with the light emitting surface facing up, and a voltage of 5.3 V is applied to the organic EL element to make dots on the PC screen via the camera. The place other than the dot was visually observed.

◎: Nowhere other than the dots is shining (black)
〇: The dots are much brighter than the places other than the dots.
Δ: The dots are shining in places other than the dots, making it difficult to see the dots.
X: It is difficult to distinguish dots from places other than dots.

The results of the above various evaluation experiments are summarized in Table I.
In the table, Dp-1 represents a phosphorescent dopant-containing solution, and Host-1 / Dp-1 or Host-2 / Dp-1 represents a mixed solution of a host compound and a phosphorescent dopant.

As is clear from the results shown in Table I, it can be seen that the organic EL device of the present invention is comprehensively superior to the organic EL device of the comparative example.

1 Organic EL element 2 Base material 3 First electrode (anode)
4 Hole injection layer 5 Hole transport layer 6 Light emitting part 6a Light emitting layer 6b Holes in the light emitting part 7 Non-light emitting part 7a Non-light emitting layer in the non-light emitting part (host layer)
8 Electron transport layer 9 Electron injection layer 10 Second electrode (cathode)
11 Extraction electrode (first electrode)
12 Extraction electrode (second electrode)
13 Adhesive layer for encapsulation 14 Encapsulation base material 1A Image display area 1U Organic functional layer unit Dp Luminous dopant Dp / Host Mixture of luminescent dopant and host compound A Thickness of non-luminous part layer B Thickness of luminescent layer 30 Inkjet head 31, 39 Pump 32 Filter 33 Piping branch 34 Waste liquid tank 35 Control unit 36, 37, 38A, 38B tank

Claims (9)

An organic electroluminescence device having an anode, at least an organic functional layer, and a cathode on a substrate.
It has a light emitting part and a non-light emitting part in the image display area including at least the organic functional layer.
The light emitting portion has a light emitting layer containing a light emitting dopant and has a light emitting layer.
The non-light emitting portion has a non-light emitting layer that does not contain an amount of a light emitting dopant that allows the light emitting phenomenon to be visually recognized, and has a non-light emitting layer.
An organic electroluminescence device characterized in that the thickness of the non-light emitting layer of the non-light emitting portion is 1.5 times or more thicker than the thickness of the light emitting layer of the light emitting portion. The organic electroluminescence device according to claim 1, wherein the light emitting portion has a portion formed by a solvent dissolving action on the upper side of the surface of the light emitting layer. Claim 1 or claim that the following relational expression (1) is satisfied when the thickness of the non-light emitting layer of the non-light emitting portion is A and the thickness of the light emitting layer of the light emitting portion is B. 2. The organic electroluminescence device according to 2.
Relational expression (1): A / B = 1.5 to 5.5 The organic electroluminescence device according to any one of claims 1 to 3, wherein the light emitting layer is a layer containing a host compound and a light emitting dopant. The non-luminescent layer is any one of claims 1 to 4, characterized in that the non-luminescent layer is an organic functional layer containing a host compound but not containing an amount of a luminescent dopant that induces a luminescence phenomenon. The organic electroluminescence element described. The organic electroluminescence device according to claim 5, wherein the host compound contained in the organic functional layer, which is a non-light emitting layer, has a molecular weight of 1000 or less. The organic electroluminescence device according to any one of claims 1 to 6, wherein a hole transport layer is provided under the non-light emitting layer. Claims 1 to 7, wherein the light emitting units are arranged in a dot shape in the image display unit region when viewed from a direction perpendicular to the surface in the image display unit region. The organic electroluminescence device according to any one of the above. A method for manufacturing an organic electroluminescent device according to any one of claims 1 to 7, wherein the organic electroluminescent device is manufactured.
In the formation of the non-light emitting portion and the light emitting portion,
A step of forming the non-emissive layer by an inkjet printing method or a wet process other than the inkjet printing method, and
It has a step of forming the light emitting layer containing a light emitting dopant by an inkjet printing method, and
An organic electroluminescence element characterized in that the difference between the solubility parameter value of the solvent of the compound-containing liquid used for forming the non-light emitting layer and the solubility parameter value of the solvent of the ink used for forming the light emitting layer is 2 or less. Production method.

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