JP2023130237A - Manufacturing method of organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

To improve uniformity of a film thickness in a region surrounded by a bank in the case where a functional membrane constructing an organic electroluminescent element is formed by a wet type film formation.SOLUTION: A manufacturing method of an organic electroluminescent element, comprises the steps of, in order: providing a plurality of open parts in a fine region by a photo-lithography method by applying a liquid-repellent resist onto a glass substrate having a conductive electrode pattern; applying functional inc containing at least one kind of functional material and at least one kind of organic solvent to the open part by a printing method; vaporizing the organic solvent contained in the functional inc by a depression drying; and sintering a film obtained by the depression drying at a temperature of 150°C or higher to obtain a functional membrane. The organic solvent contains an organic solvent having a contact angle of 26° or more and 50° or less with respect to a predetermined film.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing an organic electroluminescent device and an organic electroluminescent device manufactured using the manufacturing method.

The common method for manufacturing organic electroluminescent devices is to form organic materials into films by vacuum evaporation and laminate them, but in recent years, organic materials in solution form have been developed as a manufacturing method that is more efficient in material usage. Research on manufacturing methods using wet film formation, in which films are formed by an inkjet method or the like and laminated, is becoming more active.

In manufacturing organic electroluminescent devices, especially organic EL displays, by wet film formation, each pixel is divided by partition walls called banks, and a functional film that constitutes the organic electroluminescent device is formed in a minute area within the bank. A method of forming a film by discharging an ink, which is a composition for forming an organic electroluminescent element, using an inkjet method is being considered. At this time, a technique has been proposed to obtain a flatter film within the area surrounded by the bank by mixing various surface modifiers with the ink (Patent Documents 1 and 2).

However, in the conventional method, the flatness of the film within the region surrounded by the bank was not sufficient.

Patent Document 3 discloses a technique using two or more types of solvents having different boiling points for the purpose of forming a functional layer having a substantially flat cross-sectional shape after drying and solidification.

In particular, when using an inkjet device or the like to apply ink to an area divided by banks (partition walls) to form a film, it is necessary to make the partition walls themselves liquid repellent to prevent the ink from overflowing to the outside of the partition walls. Then, a sufficient amount of ink is applied so that the entire divided area is wetted, and then the solvent component is evaporated using various drying means such as vacuum drying to obtain a functional film. When the ink dries in the partitioned area, the edge of the ink gradually retreats from the side of the bank, gradually increasing its concentration, and finally forming a functional film. However, due to the self-pinning phenomenon in which the ink stops halfway along the bank side surface due to differences in wettability of the bank side surface or changes in the shape of the bank side surface, the ink end may not be able to sufficiently retreat along the bank side surface. If self-pinning is performed in the middle of the bank side surface in this way, the resulting functional film will take a shape that wets along the bank side surface, making it difficult to achieve a uniform film thickness.

The self-pinning phenomenon can be confirmed by measuring the receding contact angle of the ink on the side surface of the bank. However, it is difficult to measure the receding contact angle on the side surface of a bank, which has a complex structure and surface properties, and the problem is that it is difficult to control. Furthermore, the viscosity of the ink during drying increases as the concentration increases during the drying process, resulting in a loss of fluidity as an ink, resulting in self-pinning.

International Publication No. 2010/104183 JP2002-056980A Japanese Patent Application Publication No. 2015-185640

An object of the present invention is to improve the uniformity of film thickness within a region surrounded by banks when a functional film constituting an organic electroluminescent device is formed by wet film formation.

The present inventors have discovered that the contact angle of the surface obtained by treating the outermost surface of the bank with external energy and removing the liquid-repellent component from the outermost surface is related to the film shape of the functional layer. In other words, by forming a functional film using a combination of a bank and an ink containing a solvent whose contact angle is within a certain range, self-pinning can be appropriately suppressed and a uniform film can be obtained. I found out.

That is, the present invention has the following configuration.

[1]
a step of applying a liquid-repellent resist on a glass substrate having a conductive electrode pattern and forming a plurality of openings in minute regions by photolithography;
applying a functional ink containing at least one functional material and at least one organic solvent to the opening by a printing method;
Volatizing the organic solvent contained in the functional ink by drying under reduced pressure;
A method for producing an organic electroluminescent device comprising, in this order, the step of sintering the film obtained by the vacuum drying at a temperature of 150° C. or higher to obtain a functional film,
The organic solvent having a contact angle of 26° or more and less than 50° is applied to a film for contact angle measurement from which the surface of the lyophobic resist film obtained by curing the lyophobic resist is peeled off by external energy. A method for producing an organic electroluminescent device, the method including a solvent.
[2]
The method for manufacturing an organic electroluminescent device according to [1], wherein the surface of the liquid-repellent resist film is peeled off by external energy by UV/ozone treatment or plasma treatment.
[3]
The organic electroluminescent device according to [1] or [2], wherein the organic solvent having a contact angle of 26° or more and less than 50° has the highest boiling point among all the organic solvents contained in the functional ink. Production method.
[4]
Any one of [1] to [3], wherein the content of the organic solvent having a contact angle of 26° or more and less than 50° is 15% by weight or more based on all organic solvents contained in the functional ink. 1. A method for manufacturing an organic electroluminescent device according to item 1.
[5]
Any one of [1] to [4], wherein the content of the organic solvent having a contact angle of 26° or more and less than 50° is less than 50% by weight based on all organic solvents contained in the functional ink. 1. A method for manufacturing an organic electroluminescent device according to item 1.
[6]
The difference between the boiling point of the organic solvent having a contact angle of 26° or more and less than 50° and the boiling point of the organic solvent having the lowest boiling point among all the organic solvents contained in the functional ink is 20° C. or more, [ The method for producing an organic electroluminescent device according to any one of [1] to [5].
[7]
The method for producing an organic electroluminescent device according to any one of [1] to [6], wherein the functional material contains at least one hole-transporting compound and at least one electron-accepting compound. .
[8]
The method for producing an organic electroluminescent device according to any one of [1] to [7], wherein the organic solvent contained in the functional ink is dried under reduced pressure for 1 minute or more and less than 15 minutes.
[9]
The method for manufacturing an organic electroluminescent device according to any one of [1] to [8], wherein the liquid-repellent resist contains a fluorine atom-containing resin.
[10]
The method for manufacturing an organic electroluminescent device according to any one of [1] to [9], wherein the time for treating the liquid-repellent resist film with the external energy is 30 seconds or more and 300 seconds or less.
[11]
An organic electroluminescent device manufactured using the manufacturing method described in any one of [1] to [10].

According to the manufacturing method of the present invention, it is possible to improve the uniformity of the thickness of the functional film within the region surrounded by the bank.

1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to figures and the like. The embodiments described below are one embodiment for explaining the present invention, and are not intended to be interpreted as limiting the present invention, and all the embodiments described in each embodiment The configuration is not necessarily an essential configuration to solve the problems of the present invention.

Furthermore, in this specification, when the composition of the present invention is used as an ink ejected from a nozzle of an inkjet device, it may be referred to as a functional ink or simply an ink. When the composition of the present invention is used as an ink ejected from a nozzle of an inkjet device and applied to an area surrounded by a partition layer, the ink in the area surrounded by a partition layer is converted into a liquid or liquid. It is sometimes called a film, and the ink ejected from a nozzle is sometimes called a droplet.

A liquid film in which the solvent composition ratio of the liquid film changes by drying the liquid film in the region surrounded by the partition layer (bank) and volatilizing the solvent may also be referred to as a liquid or a liquid film. A film containing a functional material obtained by coating the composition of the present invention, evaporating the organic solvent, and drying the film is referred to as a functional film or a functional layer. Furthermore, a film containing an organic compound that does not contain a solvent or is dried by substantially volatilizing the solvent is referred to as an organic film. A functional film is a type of organic film.

In this specification, a bank is a structure in which a film formed using a photosensitive composition is patterned by a general photolithography method and formed into a film having divided micro regions (also called pixels). Point to the body. The divided minute region of this structure is surrounded by a bank wall having a constant height, and the entire wall surface is referred to as a bank side surface. Further, a photosensitive composition manufactured for the above purpose may be simply referred to as a resist.

In many cases where organic EL displays are manufactured using a wet method, this bank has liquid repellency and has the function of preventing the applied functional ink from overflowing. A resist used to manufacture a bank having such liquid repellency is sometimes referred to as a liquid repellent resist. In addition, a film formed using the present liquid-repellent resist and exposed and developed without particularly using a patterning mask is referred to as a liquid-repellent resist film.

<Method for manufacturing organic electroluminescent device>
The present invention includes a step of applying a liquid-repellent resist on a glass substrate having a conductive electrode pattern and forming a plurality of micro-region openings using a photolithography method, and a step of peeling off the surface of the bank using external energy. Applying a functional ink containing at least one functional material and at least one organic solvent to the opening by a printing method, and volatilizing the organic solvent contained in the functional ink by drying under reduced pressure. and a step of sintering the film obtained by the vacuum drying at a temperature of 150° C. or higher to obtain a functional film. The organic solvent contains an organic solvent having a contact angle of 26° or more and less than 50° with respect to the film for contact angle measurement from which the surface of the liquid-repellent resist film obtained by curing is peeled off by the external energy. , relates to a method for manufacturing an organic electroluminescent device. The present invention also relates to an organic electroluminescent device manufactured using the manufacturing method.

In order to suppress self-pinning on the bank side surface, the present invention uses a film for contact angle measurement obtained by peeling off the liquid-repellent component on the outermost surface of the liquid-repellent resist film to create a pseudo bank side surface and function. We investigated the relationship between solvents used in ink. An organic solvent that has a contact angle of 26° or more and less than 50° on the surface of the film for contact angle measurement (hereinafter also referred to as "organic solvent having a contact angle of 26° or more and less than 50°"). It has been discovered that by using a combination of an ink containing 100% and a bank formed by a liquid-repellent resist that provides a film for measuring the contact angle, self-pinning can be effectively suppressed and the uniformity of the film can be improved. .

<Liquid repellent resist>
The liquid-repellent resist in the present invention may be either a positive type or a negative type, but a negative type is preferable from the viewpoint of liquid repellency. In a negative liquid-repellent resist, a photosensitive composition containing (A) a photopolymerization initiator, (B) an alkali-soluble resin, (C) a photopolymerizable compound, and (D) a liquid repellent is preferred.

(A) Photopolymerization initiator (A) The photopolymerization initiator is contained in order to absorb ultraviolet rays and promote the polymerization reaction of the (C) photopolymerizable compound. The photopolymerization initiator used in this application is not particularly limited, but it absorbs moderate ultraviolet rays (i-line) with a wavelength of 350 to 400 nm from the light source of the exposure machine, accelerates the polymerization reaction, and has liquid repellency. An oxime ester photopolymerization initiator is preferred because it improves the polymerization.
For example, Japanese Patent No. 4454067, International Publication No. 2002/100903, International Publication No. 2012/45736, International Publication No. 2015/36910, International Publication No. 2006/18973, International Publication No. 2008/78678, Japanese Patent No. 4818458 International Publication No. 2005/80338, International Publication No. 2008/75564, International Publication No. 2009/131189, International Publication No. 2009/131189, International Publication No. 2010/133077, International Publication No. 2010/102502, International Publication No. 2012/68879 The photopolymerization initiators described in this issue can be used.

The content ratio of the photopolymerization initiator is not particularly limited, but is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, and It is preferably 3% by mass or more, usually 15% by mass or less, preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. When the content is equal to or more than the lower limit, sufficient liquid repellency tends to occur, and when the content is equal to or less than the upper limit, developability tends to be improved.

(B) Alkali-soluble resin (B) The alkali-soluble resin is not particularly limited as long as it can be developed with an alkaline developer. Examples of the alkali-soluble resin include various resins having a carboxyl group or a hydroxyl group, and those having a carboxyl group are preferred from the viewpoint of excellent developability. Further, an alkali-soluble resin having an ethylenically unsaturated group is preferable because the verticality of the side surface of the bank is good, and the outflow of the liquid repellent agent due to thermal melting of the bank is suppressed, so that liquid repellency is easily maintained.
(B) Although the specific structure of the alkali-soluble resin is not particularly limited, epoxy (meth)acrylate resin (B1) and/or acrylic copolymer resin (B2) are preferred.
Here, the epoxy (meth)acrylate resin (B1) is produced by adding an acid or ester compound having an ethylenically unsaturated bond (ethylenic double bond) to an epoxy resin having an aromatic ring in the main chain, and further adding a polybasic acid Or it is a resin to which its anhydride is added. Furthermore, the epoxy (meth)acrylate resin (B1) also includes a resin obtained by reacting a compound having a functional group that can further react with the carboxy group of the resin obtained by the above reaction.
For example, alkali-soluble as described in International Publication No. 2004/81621, International Publication No. 2008/129986, International Publication No. 2008/153000, International Publication No. 2018/43746, International Publication No. 2018/101314, and International Publication No. 2021/90836. Resin can be used.

The content ratio of the alkali-soluble resin (B) in the liquid-repellent resist that can be used in the present invention is not particularly limited, but is usually 5% by mass or more, preferably 10% by mass or more, and more preferably 20% by mass or more based on the total solid content. Mass % or more, more preferably 30 mass % or more, even more preferably 40 mass % or more, particularly preferably 50 mass % or more, and usually 90 mass % or less, preferably 80 mass % or less, more preferably 70 mass % It is as follows. When the content is equal to or more than the lower limit, the shape of the partition wall tends to be improved, and when the content is equal to or less than the upper limit, the liquid repellency tends to be improved.

(C) Photopolymerizable compound (C) The photopolymerizable compound is thought to increase the curability of the resist film and improve the liquid repellency. The photopolymerizable compound used here refers to a compound having one or more ethylenically unsaturated bonds in the molecule, although it is not particularly limited to the following. It is preferable to use a compound having two or more ethylenically unsaturated bonds in the molecule, from the viewpoint of enlarging the difference in developer solubility between the exposed area and the unexposed area, and the unsaturated bond is ( More preferably, it is derived from a meth)acryloyloxy group, that is, a (meth)acrylate compound.
Examples of photopolymerizable compounds include esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids; esters of aromatic polyhydroxy compounds and unsaturated carboxylic acids; aliphatic polyhydroxy compounds, aromatic polyhydroxy compounds, etc. Examples include esters obtained by esterification reactions between polyhydric hydroxy compounds, unsaturated carboxylic acids, and polybasic carboxylic acids; Esters are preferred. For example, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, 2-tris(meth)acryloyloxymethylethylphthalate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, More preferred are dipentaerythritol penta(meth)acrylate and the like.

The content of the photopolymerizable compound (C) in the liquid-repellent resist that can be used in the present invention is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more in the total solid content. The content is at least 15% by mass, more preferably at least 15% by mass, usually at most 80% by mass, preferably at most 60% by mass, more preferably at most 40% by mass, even more preferably at most 30% by mass. When the amount is at least the lower limit, the perpendicularity of the side surfaces of the partition walls during exposure tends to be good, and when it is at most the upper limit, the developability tends to be good.

(D) Liquid repellent (D) The liquid repellent preferably contains a fluorine atom-containing resin, and more preferably contains a fluorine atom-containing resin having a crosslinking group. By using such a liquid repellent, the liquid repellent resist contains a fluorine atom-containing resin or a fluorine atom-containing resin having a crosslinking group, and as a result, it is possible to impart liquid repellency to the surface of the bank, which improves functionality. When ink is applied, it is possible to prevent inks in adjacent minute areas from mixing with each other.

Examples of the crosslinking group include an epoxy group or an ethylenically unsaturated group, and an ethylenically unsaturated group is preferable from the viewpoint of suppressing outflow of the liquid-repellent component of the developer. By using a liquid repellent having a crosslinking group, it is possible to accelerate the crosslinking reaction on the surface of the formed resist film when it is exposed to light, making it difficult for the liquid repellent to flow out during the development process, and as a result, the resulting bank It can also be made to exhibit high liquid repellency. Moreover, since the resin is a fluorine atom-containing resin, the fluorine atom-containing resin tends to be oriented on the surface of the partition wall, thereby preventing the functional ink from bleeding or mixing.
The fluorine atom can be contained, for example, in the form of a fluoroalkyl group, a fluoroalkenyl group, a fluoroalkylene group, or the like. Among these, from the viewpoint of liquid repellency and prevention of bleeding and mixing of functional inks, fluoroalkyl groups and fluoroalkylene groups are preferred, and fluoroalkyl groups are more preferred.

Moreover, it is desirable that the liquid repellent is an acrylic copolymer. Being an acrylic copolymer, it tends to work to prevent functional inks from bleeding or mixing.

(D) The content ratio of the liquid repellent is not particularly limited, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more based on the total solid content, and , usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. Setting the amount above the lower limit value tends to exhibit high liquid repellency, and setting the amount below the upper limit value tends to suppress outflow to minute regions.

(Other additives)
In addition to the ethylenically unsaturated compound as component (A), the photopolymerization initiator as component (B), the alkali-soluble binder as component (C), and the liquid repellent as component (D), surfactants, colorants, and ultraviolet rays. Absorbers, polymerization inhibitors, antioxidants, development improvers, silane coupling agents, epoxy compounds, other resins, and the like can be blended as appropriate.

Further, the liquid-repellent resist is used in a state in which each component is dissolved or dispersed in a solvent as appropriate. The solvent is not particularly limited, but includes, for example, the organic solvents described below.
Glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether;
Glycol dialkyl ethers such as diethylene glycol ethyl methyl ether and diethylene glycol diethyl ether;
Glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, 3-methoxybutyl acetate;
Glycol diacetates such as 1,3-butylene glycol diacetate, 1,4-butanediol diacetate, 1,6-hexanol diacetate;
Alkoxycarboxylic acids such as ethyl acetate, propyl acetate, butyl acetate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, and ethyl 3-methoxypropionate.
Among these, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and 3-methoxy-1-butyl acetate are preferred.

<Fabrication of liquid-repellent resist film>
Normally, when a liquid-repellent resist film is formed, the liquid-repellent agent (D) is distributed on the outermost surface of the film, and the liquid-repellent component is not distributed much in the bulk region. Therefore, no liquid-repellent component exists on the side surface of the bank when minute openings are patterned using photolithography or the like. On the other hand, the bank side surface, which has properties different from normal liquid-repellent bank surfaces, is a very narrow area, and it is difficult to evaluate various physical properties such as contact angle on the bank side surface.

In the present invention, in order to evaluate the contact angle on the bank side surface where the liquid-repellent component is not well distributed, the liquid-repellent component on the outermost surface of the liquid-repellent resist film is peeled off, and the state of the bank side surface is evaluated from the resist. By reproducing the contact angle on the outermost surface of the film and measuring the contact angle on that surface, it became possible to simulate the physical property evaluation on the side surface of the bank, which is difficult to measure. In this specification, such a film for contact angle measurement is sometimes referred to as a "pseudo bank side film."

<Surface peeling of liquid-repellent resist film>
For forming the liquid-repellent resist film, a spin coating method, a die coating method, a bar coating method, a spray coating method, an inkjet method, etc. can be used, and preferably a spin coating method, a die coating method, an inkjet method can be used. More preferably, a spin coating method or a die coating method can be used. Further, it is preferable that the surface of the liquid-repellent resist film be peeled off using external energy. Examples of means for applying external energy include UV/ozone treatment such as a UV/ozone cleaning method, plasma treatment such as a plasma etching method, and excimer UV treatment such as an excimer UV method. Peeling of the surface of the liquid-repellent resist film using external energy is preferably performed by UV/ozone treatment or plasma treatment, and more preferably by plasma etching.
Preferably, the outermost surface of the liquid-repellent resist film is peeled off by external energy. In this specification, the "surface" of a liquid-repellent resist film refers to an area that includes both a region on the surface of the film where a liquid-repellent agent is distributed and an area where a liquid-repellent agent is not distributed, and the "outermost surface" It means only the area where the liquid repellent is distributed.

In order to remove the liquid repellent on the surface and bring it closer to the side surface condition, the time for treating the liquid repellent resist film with external energy is preferably 30 seconds or more, more preferably 45 seconds or more, and most preferably 60 seconds or more. On the other hand, if surface treatment is carried out for a long time, the roughness of the surface will increase and the condition will be different from that of the side surface of the bank. Therefore, the time for treating the liquid-repellent resist film with external energy is preferably 300 seconds or less; The time is more preferably 2 seconds or less, and most preferably 200 seconds or less.
It is preferable that the time for treating the liquid-repellent resist film with external energy is 30 seconds or more and 300 seconds or less, since the result of contact angle measurement is very stable.

<Contact angle>
In the present invention, the contact angle is defined as the tangent of the droplet's outermost surface at the point where the droplet's outermost surface contacts the substrate and the substrate surface when the image of a droplet dropped on a substrate is viewed from the side. This is the angle between Unless otherwise specified, contact angle values are values measured in an environment set at 23° C., and are the average value of three contact angle measurements 0.1 seconds after dropping.

[Functional ink]
According to the invention, the functional ink used in the invention contains at least one functional material and at least one organic solvent.

<Organic solvent>
Hereinafter, organic solvents that can be used in the present invention will be explained while giving examples.

(Type of organic solvent)
The organic solvent that can be used in the present invention is not particularly limited, but in order to effectively dissolve the functional material, aromatic organic solvents, chain aliphatic organic solvents, and cycloaliphatic organic solvents are preferable. Aromatic organic solvents and cycloaliphatic organic solvents are more preferred, and aromatic organic solvents are even more preferred.

Aromatic organic solvents that can be used in the present invention are not particularly limited, but preferably include non-aqueous solvents such as aromatic hydrocarbon solvents, aromatic ester solvents, aromatic ether solvents, and aromatic ketone solvents. and aromatic solvents.
In addition, within the scope of the present invention, if the contact angle of at least one organic solvent contained in the functional ink is 26° or more on the surface of the film for contact angle measurement described above, in order to improve uniformity, The condition is that the angle is more preferably 27° or more, less than 50° from the viewpoint of coatability, and more preferably less than 45°.

As the aromatic hydrocarbon solvent, benzene derivatives, naphthalene derivatives, hydrogenated naphthalene derivatives, biphenyl derivatives, and diphenylmethane derivatives are preferred.

The benzene derivative is not particularly limited, but preferably is a benzene derivative having a substituent having a total carbon number of 2 or more and 12 or less and having a linear, branched, or cyclic alkyl group as a substituent, such as n-ethylbenzene, 1, 3,5-trimethylbenzene, n-propylbenzene, isopropylbenzene, 1,3-diisopropylbenzene, 1,3,5-triisopropylbenzene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, n-pentyl Examples include benzene, n-hexylbenzene, n-heptylbenzene, n-octylbenzene, n-nonylbenzene, n-decylbenzene, dodecylbenzene, and cyclohexylbenzene.

The naphthalene derivative is not particularly limited, but preferably is a naphthalene derivative having a total number of carbon atoms of 2 or more and 6 or less and having a linear, branched, or cyclic alkyl group as a substituent, such as 1-methylnaphthalene, 2-methylnaphthalene, - Methylnaphthalene, 1-ethylnaphthalene, 2-ethylnaphthalene, 2-isopropylnaphthalene, 2,6-dimethylnaphthalene, 2,7-diisopropylnaphthalene, 1-butylnaphthalene, 2-cyclohexylnaphthalene, 1-phenylnaphthalene, etc. It will be done.

Hydrogenated naphthalene derivatives include, but are not particularly limited to, tetralin, 1,2-dihydronaphthalene, 1,4-dihydronaphthalene, etc., and these may be substituted with an alkyl group having 1 to 6 carbon atoms. good.

The biphenyl derivative is not particularly limited, but biphenyl derivatives substituted with an alkyl group having 1 to 6 carbon atoms are preferred, such as 3-ethylbiphenyl, 4-isopropylbiphenyl, 4-butylbiphenyl, and the like.

The diphenylmethane derivative is not particularly limited, but preferably is a diphenylmethane derivative substituted with an alkyl group having 1 to 6 carbon atoms, such as 1,1-diphenylethane, 1,1-diphenylpentane, 1,1-diphenylhexane, Examples include 1,1-bis(3,4-dimethylphenyl)ethane and benzyltoluene.

Examples of aromatic ester solvents include benzoic acid ester solvents, phenylacetic acid ester solvents, and phthalic acid ester solvents.

The benzoic acid ester solvent is a compound having an ester bond with benzoic acid, and a compound in which benzoic acid, which may have a substituent, and an alcohol having 1 to 12 carbon atoms are ester bonded can be used. . Although not particularly limited, substituents that may be present include a straight chain, branched, or cyclic alkyl group having 1 to 12 carbon atoms, and a straight chain, branched, or cyclic alkyl group having 1 to 12 carbon atoms. An aromatic substituent having 6 or more and 12 or less carbon atoms is preferable. There may be a plurality of these substituents, and in the case of a plurality of substituents, the total carbon number of the substituents is preferably 2 or more and 12 or less. Examples of benzoic acid ester solvents include ethyl benzoate, n-butyl benzoate, n-pentyl benzoate, isoamyl benzoate, n-hexyl benzoate, 2-ethylhexyl benzoate, benzyl benzoate, and 4-methylbenzoic acid. Examples include methyl, methyl 3-methylbenzoate, methyl 2-methylbenzoate, ethyl 4-methylbenzoate, ethyl 3-methylbenzoate, ethyl 2-methylbenzoate, and ethyl 4-methoxybenzoate.

Examples of the phenylacetate-based solvent include, but are not particularly limited to, ethyl phenylacetate and the like.

Phthalate ester solvents include, but are not particularly limited to, dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

Other preferred aromatic ester solvents include 2-phenoxyethyl acetate, 2-phenoxyethyl isobutyrate, and the like.

The aromatic ether solvent is a compound having an aromatic ring and an ether bond, and examples thereof include, but are not limited to, the following.
Examples of benzene derivatives having a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms and one ether bond include anisole, 4-methylanisole, butylphenyl ether, hexylphenyl ether, diphenyl ether, benzylphenyl ether, diphenyl ether, Benzyl ether;
Examples of diphenyl ether derivatives substituted with a linear or branched alkyl group having 1 to 6 carbon atoms include 2-phenoxytoluene, 3-phenoxytoluene, and 4-phenoxytoluene;
Examples of benzene derivatives having two ether bonds with a linear or branched alkyl group having 1 to 6 carbon atoms include 1,4-diethoxybenzene, 1-ethoxy-4-hexyloxybenzene;
Other aromatic ether solvents include 2-phenoxyethanol and phenoxyethoxyethanol:

The aromatic ketone solvent is a compound having an aromatic ring and a ketone structure, and examples thereof include 1-acetylnaphthalene, propiophenone, and 4'-ethylpropiophenone.

Note that the solvent may contain a surface modifier for controlling surface tension. By adding a small amount of the surface modifier to a liquid, it is possible to impart functionality to the liquid surface after applying the liquid or to the solid surface obtained by applying the liquid. Functions imparted here include liquid repellency, non-adhesiveness, wettability, smoothness, dispersibility, antifoaming properties, and the like.

Materials that can be used as surface modifiers are preferably materials that are easily segregated on the liquid surface, such as materials containing silicon or fluorine (polymers, oligomers, low molecules), paraffin, surfactants, etc. can be mentioned.
The surfactant here is a substance with an amphipathic chemical structure that has a hydrophilic part (group) and a hydrophobic part (group), and is a dispersant, foaming agent, and antifoaming agent. It is used in a wide range of applications, including emulsifiers, food additives, humectants, antistatic agents, wettability improvers, lubricants, and rust preventives. Such surfactants are broadly classified into those with hydrophilic parts that are cationic, anionic, amphoteric, and nonionic. Nonionic surfactants are preferred to prevent this from occurring.

(boiling point)
The organic solvent used in the present invention is not particularly limited, but preferably has a boiling point of 200°C or higher, more preferably has a boiling point of 230°C or higher, and even more preferably has a boiling point of 250°C or higher. , an organic solvent having a boiling point of 270° C. or higher is most preferred. Further, the boiling point is preferably 350°C or lower, more preferably 340°C or lower, and even more preferably 330°C or lower.

For example, ink filled in an inkjet head begins to dry from the tip of the nozzle, so the solid content concentration tends to increase at the tip of the nozzle. If this state is maintained, solid matter will begin to precipitate at the tip of the nozzle, which may eventually cause fatal damage to the inkjet device, such as clogging of the nozzle. In order to avoid troubles due to nozzle clogging, organic solvents with a boiling point of 200°C or higher are preferred, organic solvents with a boiling point of 230°C or higher are more preferred, organic solvents with a boiling point of 250°C or higher are even more preferred, and organic solvents with a boiling point of 270°C or higher are most preferred. preferable.

On the other hand, from the perspective of producing an organic electroluminescent device, since the device cannot be produced unless the organic solvent is evaporated to obtain a functional film, the boiling point must be within a range that can be dried in a vacuum drying facility. From such a viewpoint, the boiling point of the first solvent is preferably 350°C or lower, more preferably 340°C or lower, and even more preferably 330°C or lower.

(vapor pressure)
Vapor pressure is the pressure in the gas phase at which the liquid and gas phases of a solvent reach a phase equilibrium state, and the boiling point of a solvent is the temperature at which the partial pressure of the vapor pressure of the solvent is equal to the vapor pressure. . Vapor pressure can be determined by experimental methods such as the static method, boiling point method, isoteniscope, and gas flow method, but the vapor pressure in the present invention is determined using Advanced Chemistry Development (ACD/Labs) Software V11 at 25°C. It refers to the vapor pressure calculated by .02 (Copyright1994-2021 ACD/Labs).

(Type and number of organic solvents contained)
The organic solvent used in the present invention may be one type of single solvent or a mixed solvent of two or more types.

When using a mixed solvent of two or more types, two types of organic solvents with different boiling points are used to suppress drying at the nozzle tip of the inkjet head and to facilitate drying during film formation, as described above. It's okay. It is preferable to contain an organic solvent having a boiling point of 270° C. or higher so as to prevent drying at the tip of the inkjet head nozzle and clogging of the nozzle. Further, the number of organic solvents having a boiling point of 270° C. or higher may be one type, or two or more types may be used. In order to prevent the ink from drying at the nozzle tip and causing nozzle clogging, the organic solvent with a boiling point of 270°C or higher is preferably contained in an amount of 10% by weight or more based on the entire composition, and more preferably 15% by weight or more. Preferably, it is more preferably contained in an amount of 25% by weight or more.

On the other hand, since drying at the tip of the nozzle can be suppressed by a solvent with a high boiling point, the remaining solvent may include an organic solvent with a low boiling point in order to ensure the drying properties of the ink. Regarding organic solvents with a low boiling point, the boiling point is preferably 265°C or lower, more preferably 250°C or lower. The organic solvent with a low boiling point may be one type or two or more types, and is preferably contained in an amount of 30% by weight or more based on the entire composition for the purpose of assisting the drying properties of the composition. , more preferably 40% by weight or more, and even more preferably 50% by weight or more.
Furthermore, when the functional ink is within the scope of the present invention, the at least one organic solvent may exhibit a contact angle of 26° or more and less than 50° on the surface of the film for contact angle measurement described above. It is a condition.
In the present invention, since a functional film is obtained by volatilizing the organic solvent using a method such as vacuum drying, the organic solvent volatilizes roughly in the order of decreasing boiling point. Since the flatness of the functional film is most influenced by the organic solvent remaining at the end, the organic solvent having a contact angle of 26° or more and less than 50° is the most important among all the organic solvents contained in the functional ink. Preferably it has the highest boiling point.
On the other hand, if the boiling point of the organic solvent with the highest boiling point mentioned above is relatively close to the boiling point of the other organic solvents, the respective organic solvents will azeotrope during the drying process, and the organic solvent with the highest boiling point mentioned above will There is a possibility that the function of the solvent cannot be fully demonstrated. In order to prevent this, the difference between the boiling point of the organic solvent having a contact angle of 26° or more and less than 50° and the boiling point of the organic solvent having the lowest boiling point among all the organic solvents contained in the functional ink is required. It is preferable that the temperature is 20°C or higher.
The content of the organic solvent having a contact angle of 26° or more and less than 50° is preferably 5% by weight or more, more preferably 10% by weight or more based on all organic solvents contained in the functional ink. The content is preferably 15% by weight or more, more preferably 15% by weight or more, and most preferably 20% by weight or more. Further, the content of the organic solvent having a contact angle of 26° or more and less than 50° is preferably less than 90% by weight, and preferably less than 80% by weight based on all the solvents contained in the functional ink. More preferably, it is less than 70% by weight, and most preferably less than 50% by weight. Further, the content of the organic solvent having a contact angle of 26° or more and less than 50° is preferably 5% by weight or more and less than 90% by weight, more preferably 10% by weight or more and less than 80% by weight, and 15% by weight or more and less than 80% by weight. It is more preferably at least 20% by weight and less than 50% by weight, and most preferably at least 20% by weight and less than 50% by weight. By being within the above range, the solvent has a sufficient function of determining the flatness of the film, and other solvents can be appropriately included in consideration of solubility and the like.

In addition, in this invention, the boiling point of a solvent is the value measured under atmospheric pressure.

(combination of organic solvents)
Although not particularly limited, examples of combinations of organic solvents with a high boiling point and organic solvents with a low boiling point include benzene which may have a substituent, naphthalene which may have a substituent, and organic solvents with a substituent. Preferably, it is diphenylmethane which may have a substituent, biphenyl which may have a substituent, benzoic acid ester, aromatic ether, or aromatic ketone.

Preferably, the organic solvent with a high boiling point is octylbenzene, nonylbenzene, decylbenzene, dodecylbenzene, hexyl benzoate, 2-ethylhexyl benzoate, benzyl benzoate, acetylnaphthalene, methyl naphthalene acetate, ethyl naphthalene acetate, isopropylnaphthalene, diisopropyl Naphthalene, butylnaphthalene, pentylnaphthalene, methoxynaphthalene, dimethyl phthalate, diethyl phthalate, ethyl biphenyl, isopropylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, butylbiphenyl, 1,1-diphenylethane, 1,1-diphenylpropane, 1 , 1-diphenylbutane, 1,1-diphenylpentane, 1,1-diphenylhexane, and 2-phenoxyethyl isobutyrate.

Preferably, the organic solvent with a low boiling point is methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, ethyl benzoate, propyl benzoate, butyl benzoate, isobutyl benzoate, pentyl benzoate, isopentyl benzoate, methyl toluate, toluic acid. One or more types of ethyl may be mentioned.

<Viscosity>
The functional ink of the present invention preferably has a viscosity at 23° C. of 1 mPas or more and 20 mPas or less, considering a coating method in which it is filled into an inkjet head and ejected.
In general, inkjet heads that use piezoelectric elements push out the composition filled in the ink chamber in the head using the deformation pressure of the piezoelectric element, so if the composition has a viscosity exceeding 20 mPas, the pressure of the piezoelectric element will increase. It runs out and cannot be discharged. On the other hand, the viscosity of the composition is preferably 1 mPas or more from the viewpoint of making the composition easy to retain ink within the head so as not to drip from the nozzle.
In the present invention, the viscosity of the organic solvent can be measured using an E-type viscometer RE85L (manufactured by Toki Sangyo) at a cone plate rotation speed of 20 rpm to 100 rpm in an environment of 23°C.

<Surface tension>
The surface tension of the functional ink of the present invention is preferably 25 mN/m or more, and preferably 45 mN/m or less. It is thought that when the surface tension of the functional ink is within this range, stable ejection with an inkjet device and stable film formation are possible. In the case of functional ink with low surface tension, it wets and spreads very well on the nozzle plate of an inkjet head, causing unstable ejection and flight deflection. Furthermore, if the surface tension is low, the discharged composition tends to stretch for a long time without running out at an appropriate point, which can easily cause satellite formation. On the other hand, if the surface tension is too high, convection due to Laplace pressure tends to occur during drying after coating on the pixel portion of the substrate, and the film shape tends to become unstable.

The surface tension of the organic solvent and functional ink in the present invention can be determined by the plate pulling method using a platinum plate or the pendant drop test using a contact angle meter DMо-501 (manufactured by Kyowa Kaimen Kagaku) in an environment of 23.0°C. It can be measured by the method.

[Other ingredients]
In the present invention, the functional ink may contain components other than the functional material and the organic solvent, such as an antioxidant and an additive that changes the physical properties of the functional ink. These components may be important factors that determine the storage stability and ejection stability from an inkjet head of functional inks, but it is preferable that they have a major impact on the original performance of the functional ink. Therefore, it is preferably 1% by weight or less, more preferably 0.1% by weight or less, and even more preferably 0.05% by weight or less based on the entire functional ink.

[Functional materials]
A functional material is a material that has functions such as charge transport and charge injection, or improves these functions. For charge transport, hole transport properties are preferred, and for charge injection, hole injection properties are preferred. A material having a function of improving charge transporting property is a material having a function of improving charge transporting property of another material having charge transporting property. A material having a function of improving charge injection property is a material having a function of improving charge injection property of another material having charge injection property. For example, by doping an electron-accepting material into a hole-transporting material, the electron-accepting material oxidizes the hole-transporting material to generate cation radicals, which improves the hole-transporting property of the hole-transporting material and/or Hole injection properties are improved. In this case, the electron-accepting material is a material that improves the hole-transporting and/or hole-injecting properties of the hole-transporting material.

Further, as the functional material in the present invention, preferably a material for a hole injection layer or a material for a hole transport layer, which will be described later, can be used, and a material for a hole injection layer is particularly preferred.
Hereinafter, details of the functional materials that can be used in the present invention will be explained while showing specific examples, but the scope of the present invention is not limited to the functional materials described below.

<Molecular weight of charge transporting compound>
The charge-transporting compound in the present invention may be a high-molecular compound or a low-molecular compound, but preferably a high-molecular compound.

Charge-transporting polymer compounds generally have a large charge-transporting ability in the direction of the main chain of the polymer compound, so the larger the average molecular weight, the more stable charge transport can be realized. In order to ensure the function of transporting charges, the weight average molecular weight is 10,000 or more, preferably 12,000 or more, and more preferably 15,000 or more. On the other hand, a polymer compound with a large weight average molecular weight has a characteristic that it has a high viscosity when made into an ink, and in order to obtain the above-mentioned preferred viscosity range, it is preferable that the weight average molecular weight is reduced to a certain extent. Specifically, the weight average molecular weight of the polymer compound is usually 1,000,000 or less, preferably 500,000 or less, more preferably 100,000 or less, even more preferably 70,000 or less, and 50,000 or less. Particularly preferred.

Regarding charge transporting low molecular weight compounds, the molecular weight is generally 5,000 or less, preferably 4,000 or less, more preferably 3,000 or less, and 2,500 or less. is more preferable, and particularly preferably 2,000 or less. On the other hand, when forming a general functional film, it is baked at a certain temperature to volatilize the remaining solvent and form a functional film free of impurities, which is sufficient for use as an organic electroluminescent device. functions. At this time, if a material with low heat resistance is used, phenomena such as film shrinkage and film dropout will occur, making it impossible to obtain a flat film. From the viewpoint of ensuring the heat resistance of the film, the molecular weight of the charge transporting low molecular weight compound is preferably 500 or more, more preferably 650 or more, and even more preferably 800 or more.

Further, the functional ink of the present invention preferably contains an electron-accepting compound in order to improve charge transport performance. Further, the functional ink of the present invention preferably contains at least one hole-transporting compound and at least one electron-accepting compound as the functional material.

Note that the weight average molecular weight and number average molecular weight of the charge transporting polymer compound in the present invention are determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the elution time is shorter for higher molecular weight components, and the elution time is longer for lower molecular weight components. However, using a calibration curve calculated from the elution time of polystyrene (standard sample) of known molecular weight, the elution time of the sample can be adjusted to the molecular weight. By converting, the weight average molecular weight and number average molecular weight are calculated.

<Bridging group>
In the present invention, the charge transporting low molecular weight compound may have a crosslinking group in order to prevent the charge transporting low molecular weight compound from dissolving into the solvent of the composition that is further applied to the upper layer of the functional film. preferable. In this case, the number of crosslinking groups contained in one molecule of the charge-transporting low-molecular compound is preferably two or more in order to prevent the charge-transporting material alone from being chain-linked and dissolving. Similarly, in the charge transporting polymer compound, the number of crosslinking groups contained in one repeating unit is preferably two or more. Furthermore, in order to more reliably suppress the elution of the charge transporting polymer compound, it is preferable that there are two or more crosslinking groups per molecular weight of 10,000.

The crosslinking group is preferably a substituent that chemically reacts with external force such as light or heat, and preferred examples of the crosslinking group include, but are not limited to, thermally crosslinking groups that undergo a crosslinking reaction with heat. Examples include groups derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, an acrylic group, and a styryl group. Note that any crosslinking group may have a substituent, and methyl group, methoxy group, etc. are preferable.
As described above, the functional ink of the present invention preferably contains a functional material having a crosslinking group. It is more preferable that all the functional materials contained in the functional ink of the present invention have a crosslinking group.

[Content of organic solvent and functional materials]
The content of the functional material in the functional ink of the present invention is not particularly limited, but is preferably 0.1% by weight or more, more preferably is 0.5% by weight or more, more preferably 1.0% by weight or more. Further, from the viewpoint of suppressing precipitation in the functional ink, the content is preferably 20% by weight or less, more preferably 15% by weight or less, and still more preferably 10% by weight or less.
Therefore, the content of the organic solvent in the functional ink of the present invention is preferably 99.9% by weight or less, more preferably 99.5% by weight or less, even more preferably 99.0% by weight or less, and preferably 80% by weight or less. It is at least 85% by weight, more preferably at least 90% by weight.

In the present invention, the charge-transporting low-molecular compound is a material used to improve the uniformity of the thickness of the functional film within the region partitioned by banks, and is 10% by weight or more based on the total functional material. The content is preferably 15% by weight or more, and even more preferably 20% by weight or more. On the other hand, if the content of the charge-transporting low-molecular-weight compound increases, there is a problem in terms of heat resistance as described above, so the content is preferably 75% by weight or less, and 60% by weight or less based on the total functional material. More preferably, it is 50% by weight or less.
Further, in the present invention, the charge transporting polymer compound is a material mainly used for charge transport, and preferably accounts for 20% by weight or more, and preferably 25% by weight or more based on the total functional material. is more preferable, and even more preferably 30% by weight or more. On the other hand, if the content of the charge-transporting polymer compound increases, it becomes difficult to form a flat film due to the increase in viscosity during the drying process, so the content should be 90% by weight or less based on the total functional material. It is preferably 85% by weight or less, more preferably 80% by weight or less.
In addition, considering the above, the content ratio of the low molecular weight compound and the high molecular weight compound should be 1:0.3 to 3, especially 1:1 to 2 in terms of weight ratio. It is preferable.

When the functional ink of the present invention contains an electron-accepting compound, from the viewpoint of generating carriers for the charge-transporting compound and improving conductivity, the electron-accepting compound should be added at 1% by weight based on all functional materials. % or more, more preferably 3% by weight or more, even more preferably 5% by weight or more. On the other hand, if an excessive amount of an electron-accepting compound containing fluorine is included, the surface energy of the functional film decreases and it becomes difficult to apply a layered coating. It is preferably at most 30% by weight, more preferably at most 30% by weight, even more preferably at most 20% by weight.

In addition, the content ratio of the charge transporting compound (preferably the total of the charge transporting polymer compound and the charge transporting low molecular weight compound) and the electron accepting compound is determined by the weight ratio of charge transporting compound:electron accepting compound. From the above point of view, it is preferable that the ratio is 1:0.01 to 1, particularly 1:0.05 to 0.2.

[Preparation of functional ink]
The functional ink in the present invention can be prepared by mixing a functional material and an organic solvent, and dissolving or dispersing the mixture by heating for a certain period of time. In order to uniformly dissolve or disperse the functional material in the solvent, the heating temperature is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, for example 100 to 115°C. Further, the heating time is preferably 30 minutes or more, more preferably 45 minutes or more, and even more preferably 60 minutes or more, for example 60 to 180 minutes.

The heated functional ink is filtered using a membrane filter, depth filter, etc. to remove coarse particles before use. Considering that the functional ink is applied by ejection from a nozzle of an inkjet head, the pore diameter of the filter is preferably 0.5 μm or less, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less.

[Film formation by wet film formation method]
The composition of the present invention is suitably used for forming a functional film in the production of organic electroluminescent devices. The structure of the organic electroluminescent device is as described below.

The organic electroluminescent device according to the present invention usually has a substrate provided with electrodes, and light emitting pixels in minute regions partitioned by partition walls called a liquid-repellent partition layer (bank). A functional film is formed by discharging the functional ink of the present invention into a micro region defined by the partition layer, drying it, and heating it appropriately.

The ejection method is a method of ejecting droplets smaller than a micro area partitioned by a partition layer from a micro nozzle, and the function of the present invention is to eject a plurality of droplets to form a micro area partitioned by a partition layer. It is preferable to fill it with a synthetic ink. The ejection method is preferably an inkjet method.

In the wet film-forming method, a functional ink is filled in a microscopic area defined by a bank, and then the solvent is evaporated and dried using an appropriate means to obtain a functional film. Means for volatilization and drying include, but are not limited to, heating drying and reduced pressure drying. For example, vacuum drying refers to placing a substrate coated with a composition in a vacuum chamber made of metal or glass that can be opened and closed, and evaporating the solvent by reducing the pressure of the atmosphere inside the chamber with a vacuum pump or the like. Vacuum pumps typically include rotary oil pumps, mechanical booster pumps, dry scroll pumps, dry roots pumps, turbomolecular pumps, and cryopumps.
The time for drying the organic solvent contained in the functional ink under reduced pressure is set to 1. In order to lower the pin position of the functional ink over a moderately long period of time and to prevent the organic solvent from continuing to touch the bank for too long, It is preferably at least 2 minutes and less than 15 minutes, more preferably at least 2 minutes and less than 12 minutes, and even more preferably at least 3 minutes and less than 10 minutes.

If the organic solvent in the present invention has a preferable boiling point range, it can be sufficiently volatilized using the pump, but in order to sufficiently dry even a small amount of residual solvent, heating drying may be performed subsequently. Furthermore, heating is performed to crosslink the crosslinking groups possessed by the charge transporting polymer compound, low molecular weight compound, and, if present, the functional material such as the electron accepting compound according to the present invention. The heating step can serve as heating for crosslinking as well as drying. It is preferable that the heating drying also serves as heating for crosslinking, that is, that drying and crosslinking are performed by heating, also from the viewpoint of reducing the number of steps. The heating temperature is preferably a temperature and time at which the functional film does not crystallize or aggregate.

The heating temperature of the functional material is usually 80°C or higher, preferably 100°C or higher, more preferably 150°C or higher, more preferably 200°C or higher, and usually 300°C or lower, preferably 270°C or lower, and even more preferably 240°C. It is as follows. The heating time is usually 1 minute or more, preferably 3 minutes or more, more preferably 5 minutes or more, and usually 120 minutes or less, preferably 90 minutes or less, more preferably 60 minutes or less.

Heating can be performed using a hot plate, oven, infrared irradiation, or the like. In the case of infrared irradiation that directly gives molecular vibrations, a heating time close to the lower limit above is sufficient; in the case of hot plate heating, where the substrate is in direct contact with the heat source or the heat source and the substrate are placed extremely close, the heating time is longer than infrared irradiation. requires a long time. In the case of oven heating, that is, in the case of heating with a gas in the oven, usually air or an inert gas such as nitrogen or argon, it takes time for the temperature to rise, so a heating time close to the upper limit of the above heating time is preferred. The heating time is appropriately adjusted depending on the heating method.

It is important that this heating step is performed under conditions that cause the crosslinking groups of the functional materials such as charge transporting polymer compounds and low molecular weight compounds according to the present invention to undergo a crosslinking reaction, and for this purpose, the heating temperature is The temperature is preferably at least the crosslinking initiation temperature of the crosslinking group possessed by the charge-transporting polymer compound, low-molecular compound, and, if present, the electron-accepting compound, etc. according to the present invention.

In the process of drying the functional ink of the present invention by volatilizing the solvent in the functional ink, the pin position of the functional ink on the side surface of the bank is lowered. However, if it dries too quickly, there will not be enough time to lower the pin position and it will not be as effective. Therefore, it takes 60 seconds for the pressure of the atmosphere in the vacuum chamber in which vacuum drying is performed to become lower than the vapor pressure of the organic solvent, which has the lowest vapor pressure among the organic solvents contained in the functional ink of the present invention. It is preferable that the above is the case. On the other hand, if the functional ink continues to touch the side surface of the bank, a problem arises in that the material forming the bank gradually dissolves from the bank into the organic solvent of the functional ink. Therefore, the time it takes for the pressure of the atmosphere in the vacuum chamber in which vacuum drying is performed to reach a pressure lower than that of the organic solvent that has the lowest vapor pressure among the organic solvents contained in the functional ink of the present invention. is preferably 900 seconds or less.

[Functional membrane]
The functional film formed by the functional ink of the present invention is preferably a film in which the crosslinking groups of the charge-transporting polymer compound and the low-molecular compound that are the functional materials are crosslinked.
The functional material contained in the functional film is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, and substantially 100% by weight. Most preferably, the upper limit is 100% by weight. Substantially 100% by weight means that the functional membrane may contain trace amounts of additives, residual solvents, and impurities. When the content of the functional material in the functional film is within this range, the function of the functional material can be expressed more effectively.

[Layer structure and formation method of organic electroluminescent device]
Preferred examples of embodiments of the layer structure and the method for forming the organic electroluminescent device manufactured using the functional ink of the present invention (hereinafter sometimes referred to as "organic electroluminescent device of the present invention") are as follows. , will be explained with reference to FIG.

FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device 10 of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is a hole blocking layer, 7 is an electron transport layer, 8 is an electron injection layer, 9 each represents a cathode.

The organic electroluminescent device of the present invention has an anode, a light-emitting layer, and a cathode as essential constituent layers, but if necessary, as shown in FIG. There may be other functional layers in between.

[substrate]
The substrate 1 serves as a support for the organic electroluminescent device. As the substrate 1, a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, etc. are used. Particularly preferred is a glass plate; a plate made of transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, polysulfone, or the like. When using a synthetic resin substrate, it is preferable to pay attention to gas barrier properties. The gas barrier property of the substrate is preferably large because the organic electroluminescent element is unlikely to be degraded by outside air passing through the substrate. Therefore, one preferable method is to provide a dense silicon oxide film or the like on at least one side of the synthetic resin substrate to ensure gas barrier properties.

[anode]
The anode 2 is an electrode that plays the role of injecting holes into the layer on the light emitting layer 5 side.
The anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum, or an alloy of these metals with indium, copper, tellurium, palladium, or aluminum, or an oxide of indium and/or tin. It is composed of metal oxides such as, metal halides such as copper iodide, carbon black, or conductive polymers such as poly(3-methylthiophene), polypyrrole, polyaniline, etc.

The anode 2 is usually formed by a method such as a sputtering method or a vacuum evaporation method.
When forming the anode 2 using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., these fine particles are mixed with appropriate materials. The anode 2 can also be formed by dispersing it in a binder resin solution and applying it on the substrate 1.
In the case of a conductive polymer, a thin film can also be formed directly on the substrate 1 by electrolytic polymerization.
The anode 2 can also be formed by coating a conductive polymer on the substrate 1 (Appl. Phys. Lett., vol. 60, p. 2711, 1992).

The anode 2 usually has a single layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

The thickness of the anode 2 may be appropriately selected depending on the required transparency and the like. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually about 5 nm or more, preferably about 10 nm or more, and usually about 1000 nm or less, preferably about 500 nm or less. As long as it is opaque, the thickness of the anode 2 is arbitrary. A substrate 1 having the function of the anode 2 may also be used. It is also possible to laminate different conductive materials on the anode 2 described above.

In order to remove impurities attached to the anode 2, adjust the ionization potential, and improve hole injection properties, the surface of the anode 2 is subjected to ultraviolet (UV)/ozone treatment, oxygen plasma, or argon plasma treatment. It is preferable to do so.

[Pixel division layer]
The present invention includes a step of applying a liquid-repellent resist onto a glass substrate having a conductive electrode pattern and forming a plurality of micro-area openings by photolithography.
Examples of the method for applying the liquid-repellent resist include a method using a coating device such as a roll coater, reverse coater, bar coater, spinner (rotary coating device), die coater, or inkjet on the substrate. If necessary, the solvent is removed by drying to form a liquid-repellent resist layer.

Next, in the exposure step, the liquid-repellent resist is irradiated with active energy rays such as ultraviolet rays and excimer laser light using a mask, and the liquid-repellent resist is partially exposed according to the pattern of the pixel dividing layer. For exposure by ultraviolet ray irradiation, a light source that emits ultraviolet rays such as a high pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a carbon arc lamp, etc. can be used. Although the exposure amount varies depending on the composition of the photosensitive resin composition, it is preferably about 10 to 400 mJ/cm ² , for example.
In the case of a negative liquid-repellent resist, a pattern having multiple openings in minute areas of 10 to 500 μm can be created by using a mask in which light-shielding parts of 10 to 500 μm are arranged in a line or rectangular shape. can be provided.
Next, in a developing step, a pattern is formed by developing the liquid-repellent resist that has been exposed to light in accordance with the pattern of the pixel dividing layer. The developing method is not particularly limited, and a dipping method, a spray method, etc. can be used. Specific examples of developing solutions include organic ones such as dimethylbenzylamine, monoethanolamine, diethanolamine, and triethanolamine, and aqueous solutions such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, and quaternary ammonium salts. Can be mentioned. Moreover, an antifoaming agent and a surfactant can also be added to the developer.

Thereafter, the developed liquid-repellent resist is post-baked and cured by heating to obtain a pixel segmentation layer. Post-baking is preferably performed at 150-250°C for 15-60 minutes.
The liquid-repellent resist used for manufacturing the pixel dividing layer in the present invention is functional on the film from which the liquid-repellent agent on the outermost surface of the liquid-repellent resist film formed using the liquid-repellent resist is removed as described above. The condition is that the contact angle of at least one organic solvent contained in the sexual ink is 26° or more and less than 50°.

After pattern formation, the surface of the substrate is treated using external energy in order to remove residues from resist coating and photolithography. As the external energy, ultraviolet (UV)/ozone, oxygen plasma, plasma, etc. are preferable.

[Hole injection layer]
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5. When providing the hole injection layer 3, the hole injection layer 3 is usually formed on the anode 2.

The method for forming the hole injection layer 3 may be a vacuum evaporation method or a wet film formation method, and is not particularly limited. The hole injection layer 3 is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Hole transport material>
The composition for forming a hole injection layer usually contains a hole transport material and a solvent as constituent materials of the hole injection layer 3.

The hole transport material is usually a compound having a hole transport property used in the hole injection layer 3 of an organic electroluminescent device, even if it is a polymer compound such as a polymer, or a monomer, etc. It may be a low-molecular compound, but a high-molecular compound is preferable. In addition, when applying the scope of the present invention to the hole injection layer 3, at least one hole transporting polymer material having a crosslinking group having a weight average molecular weight of 10,000 or more and at least one type of hole transporting polymer material having a weight average molecular weight of 5. ,000 or less of a crosslinking group, and at least one type of aromatic organic solvent.

As the hole transport material, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transport materials include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked with fluorene groups, hydrazone derivatives, silazane derivatives, and silanamine derivatives. , phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon, and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative, the aromatic amine itself and a compound having an aromatic amine as its main skeleton, and even if it is a polymer, it may be a monomer. There may be.

The hole transport material used as the material for the hole injection layer 3 may contain any one type of such compounds alone, or may contain two or more types of such compounds. When containing two or more hole transport materials, the combination is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two or more other hole transport materials are used. It is preferable to use them together.

Among the above-mentioned examples, aromatic amine compounds are preferable as the hole transport material, and aromatic tertiary amine compounds are particularly preferable from the viewpoint of amorphous property and visible light transmittance. The aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and also includes a compound having a group derived from an aromatic tertiary amine.

The type of aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, polymer compounds (polymerized compounds with repeating units) having a weight average molecular weight of 1,000 or more and 1,000,000 or less are preferred. preferable. Preferred examples of aromatic tertiary amine polymer compounds include polymer compounds having repeating units represented by the following formula (1) or the following formula (11).

(In formula (1),
Ar ³ represents an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent,
Ar ⁴ is a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group which may have a substituent, or the aromatic hydrocarbon group and the aromatic heterocyclic group are directly or Represents a divalent group in which multiple groups are connected via a linking group. )

In the above formula (1), when a plurality of aromatic hydrocarbon groups and aromatic heterocyclic groups are connected via a connecting group, the connecting group is a divalent connecting group, for example -O- 1 to 30, preferably 1 to 5, groups selected from a group, a -C(=O)- group, and a -CH ₂ - group (which may have a substituent) in any order, and further Preferably, a group formed by linking 1 to 3 groups is mentioned.
Among the linking groups, aromatic carbide in which a plurality of Ar ⁴ 's in formula (1) are linked via a linking group represented by the following formula (2) is superior in hole injection into the light emitting layer. A hydrogen group or an aromatic heterocyclic group is preferred.

(In formula (2),
y1 represents an integer from 1 to 10,
R ⁸ and R ⁹ each independently represent a hydrogen atom or an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group which may have a substituent.
When a plurality of R ⁸ and R ⁹ are present, they may be the same or different. )

In the above formula (11), x1, x2, x3, x4, x5, and x6 each independently represent an integer of 0 or more. However, x3+x4≧1. Ar ¹¹ , Ar ¹² and Ar ¹⁴ each independently represent a divalent aromatic ring group having 30 or less carbon atoms which may have a substituent. Ar ¹³ represents a divalent aromatic ring group having 30 or less carbon atoms which may have a substituent or a divalent group represented by the following formula (12), and Q ¹¹ and Q ¹² are each independently represents a hydrocarbon chain having 6 or less carbon atoms which may have an oxygen atom, a sulfur atom, and a substituent, and S ¹ to S ⁴ are each independently a group represented by the following formula (13). expressed.
In addition, the aromatic ring group here refers to an aromatic hydrocarbon group and an aromatic heterocyclic group.

Examples of the aromatic ring group for Ar ¹¹ , Ar ¹² and Ar ¹⁴ include a monocyclic ring, 2 to 6 condensed rings, or a group in which two or more of these aromatic rings are connected. Specific examples of monocyclic or 2-6 fused ring aromatic ring groups include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring. , fluoranthene ring, fluorene ring, biphenyl group, terphenyl group, quaterphenyl group, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, Divalent groups derived from a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a shinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring. . Among these, a divalent group derived from a benzene ring, a naphthalene ring, a fluorene ring, a pyridine ring, or a carbazole ring or a biphenyl group are preferred because they efficiently delocalize negative charges and are excellent in stability and heat resistance.
Examples of the aromatic ring group for Ar ¹³ are the same as those for Ar ¹¹ , Ar ¹² , and Ar ¹⁴ .

In the above formula (12), R ¹¹ represents an alkyl group, an aromatic ring group, or a trivalent group consisting of an alkyl group having 40 or less carbon atoms and an aromatic ring group, and these may have a substituent. R ¹² represents an alkyl group, an aromatic ring group, or a divalent group consisting of an alkyl group having 40 or less carbon atoms and an aromatic ring group, and these may have a substituent. Ar ³¹ represents a monovalent aromatic ring group or a monovalent crosslinking group, and these groups may have a substituent. x7 represents 1 to 4. When x7 is 2 or more, a plurality of R ^12s may be the same or different, and a plurality of Ar ^31s may be the same or different. The asterisk (*) indicates the bond with the nitrogen atom in formula (11).

The aromatic ring group for R ¹¹ is preferably one monocyclic or condensed aromatic ring group having 3 or more and 30 or less carbon atoms, or a group in which 2 to 6 of these are linked. Specific examples include benzene. trivalent groups derived from rings, fluorene rings, naphthalene rings, carbazole rings, dibenzofuran rings, dibenzothiophene rings, and groups in which 2 to 6 of these are linked.
The alkyl group for ^R11 is preferably a linear, branched, or ring-containing alkyl group having 1 to 12 carbon atoms, and specific examples include methane, ethane, propane, isopropane, butane, isobutane, pentane, and hexane. , groups derived from octane, and the like.
The group consisting of an alkyl group having 40 or less carbon atoms and an aromatic ring group for ^R11 is preferably a straight chain, branched, or ring-containing alkyl group having 1 or more carbon atoms and 12 or less carbon atoms, and a monomer group having 3 or more carbon atoms and 30 or less carbon atoms. Examples include a group in which one ring or fused ring aromatic ring group or 2 to 6 linked groups are connected.

Specific examples of the aromatic ring group for ^R12 include a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a divalent group derived from a connecting ring having 30 or less carbon atoms. It will be done.
Specific examples of the alkyl group for R ¹² include divalent groups derived from methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane, and octane.

Specific examples of the aromatic ring group of Ar ³¹ include monovalent groups derived from benzene rings, fluorene rings, naphthalene rings, carbazole rings, dibenzofuran rings, dibenzothiophene rings, and connecting rings having 30 or less carbon atoms. It will be done.

Examples of preferable structures of formula (12) include the following structures, and the main chain benzene ring or fluorene ring in the structure below, which is a partial structure of R ¹¹ , may further have a substituent.

Examples of the bridging group for Ar ³¹ include a group derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, an acrylic group, and the like. In view of the stability of the compound, a group derived from a benzocyclobutene ring or a naphthocyclobutene ring is preferred.

In the above formula (13), x and y represent integers of 0 or more. Ar ²¹ and Ar ²³ each independently represent a divalent aromatic ring group, and these groups may have a substituent. Ar ²² represents a monovalent aromatic ring group which may have a substituent, R ¹³ represents an alkyl group, an aromatic ring group, or a divalent group consisting of an alkyl group and an aromatic ring group; It may have a substituent. Ar ³² represents a monovalent aromatic ring group or a monovalent crosslinking group, and these groups may have a substituent. The asterisk (*) indicates the bond with the nitrogen atom in formula (11).

Examples of the aromatic ring group for Ar ²¹ and Ar ²³ are the same as those for Ar ¹¹ , Ar ¹² and Ar ¹⁴ .

Examples of the aromatic ring group for Ar ²² and Ar ³² include a monocyclic ring, 2 to 6 condensed rings, or a group in which two or more of these aromatic rings are connected. Specific examples include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring, biphenyl group, and terphenyl group. , quaterphenyl group, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring , thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benziisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline Examples include monovalent groups derived from a ring, a shinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring. Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a fluorene ring, a pyridine ring, or a carbazole ring or a biphenyl group are preferred because they efficiently delocalize negative charges and are excellent in stability and heat resistance.

Examples of the alkyl group or aromatic ring group for R ¹³ are the same as those for R ¹² .

The crosslinking group for Ar ³² is not particularly limited, but preferable examples include a group derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, an acrylic group, and the like.

Each of the above Ar ¹¹ to Ar ¹⁴ , R ¹¹ to R ¹³ , Ar ²¹ to Ar ²³ , Ar ³¹ to Ar ³² , Q ¹¹ , and Q ¹² further has a substituent as long as it does not go against the spirit of the present invention. You can leave it there. The molecular weight of the substituent is preferably 400 or less, and more preferably 250 or less. The types of substituents are not particularly limited, but examples include one or more types selected from the following substituent group W.

[Substituent group W]
Alkyl groups having 1 or more carbon atoms, preferably 10 or less, and more preferably 8 or less, such as methyl and ethyl groups; Alkyl groups having 2 or more carbon atoms, preferably 11 or less, and more preferably 5 or less, such as vinyl groups; Alkenyl group; an alkynyl group having 2 or more carbon atoms, preferably 11 or less, more preferably 5 or less, such as an ethynyl group; a methoxy group, an ethoxy group, etc. having 1 or more carbon atoms, preferably 10 or less, more preferably Alkoxy group of 6 or less; aryloxy group having 4 or more carbon atoms, preferably 5 or more, preferably 25 or less, more preferably 14 or less, such as phenoxy group, naphthoxy group, pyridyloxy group; methoxycarbonyl group, ethoxycarbonyl group an alkoxycarbonyl group having 2 or more carbon atoms, preferably 11 or less, more preferably 7 or less; such as a dimethylamino group, diethylamino group, etc. having 2 or more carbon atoms, preferably 20 or less, more preferably 12 or less dialkylamino group; diarylamino group having 10 or more carbon atoms, preferably 12 or more, preferably 30 or less, more preferably 22 or less carbon atoms, such as diphenylamino group, ditolylamino group, N-carbazolyl group; phenylmethylamino group, etc. An arylalkylamino group having 6 or more carbon atoms, more preferably 7 or more, preferably 25 or less, still more preferably 17 or less; an acetyl group, a benzoyl group, etc. having 2 or more carbon atoms, preferably 10 or less, and Acyl group preferably having 7 or less; halogen atom such as fluorine atom or chlorine atom; haloalkyl group having 1 or more carbon atoms, preferably 8 or less, and more preferably 4 or less carbon atoms such as trifluoromethyl group; methylthio group, ethylthio group Alkylthio groups having 1 or more carbon atoms, preferably 10 or less, more preferably 6 or less carbon atoms, such as; phenylthio groups, naphthylthio groups, pyridylthio groups, etc., having 4 or more carbon atoms, preferably 5 or more carbon atoms, preferably 25 or less; More preferably an arylthio group with 14 or less; a silyl group with 2 or more carbon atoms, preferably 3 or more, preferably 33 or less, more preferably 26 or less, such as a trimethylsilyl group or triphenylsilyl group; a trimethylsiloxy group, triphenyl A siloxy group having 2 or more carbon atoms, preferably 3 or more, preferably 33 or less, more preferably 26 or less, such as a siloxy group; a cyano group; a phenyl group, a naphthyl group, etc. having 6 or more carbon atoms, preferably 30 More preferably an aromatic hydrocarbon group having 18 or less carbon atoms; an aromatic heterocyclic group having 3 or more carbon atoms, preferably 4 or more carbon atoms, preferably 28 or less carbon atoms, and more preferably 17 or less carbon atoms, such as a thienyl group or a pyridyl group.

Among the substituent group W, an alkyl group or an alkoxy group is preferable from the viewpoint of improving solubility, and an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable from the viewpoint of charge transportability and stability.

In particular, among polymer compounds having repeating units represented by formula (11), those having repeating units represented by formula (14) below have extremely high hole injection and transport properties. preferable.

In the above formula (14), R ²¹ to R ²⁵ each independently represent an arbitrary substituent. Specific examples of the substituents R ²¹ to R ²⁵ are the same as the substituents described in [Substituent Group W] above.
s and t each independently represent an integer of 0 or more and 5 or less.
u, v, and w each independently represent an integer of 0 or more and 4 or less.

Preferred examples of aromatic tertiary amine polymer compounds include polymer compounds containing repeating units represented by the following formula (15) and/or formula (16).

In the above formulas (15) and (16), Ar ⁴⁵ , Ar ⁴⁷ and Ar ⁴⁸ each independently have a monovalent aromatic hydrocarbon group which may have a substituent or a substituent. represents a monovalent aromatic heterocyclic group. Ar ⁴⁴ and Ar ⁴⁶ each independently represent a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. R ⁴¹ to R ⁴³ each independently represent a hydrogen atom or an arbitrary substituent.

Specific examples, preferred examples, examples of optional substituents, and preferred examples of Ar ⁴⁵ , Ar ⁴⁷ and Ar ⁴⁸ are the same as those for Ar ²² , and specific examples and preferred examples of Ar ⁴⁴ and Ar ⁴⁶ are as follows. Examples, examples of substituents that may be present, and examples of preferable substituents are the same as those for Ar ¹¹ , Ar ¹² and Ar ¹⁴ . R ⁴¹ to R ⁴³ are preferably a hydrogen atom or a substituent listed in the above-mentioned [substituent group W], and more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group or aromatic heterocyclic group.

Preferred specific examples of repeating units represented by formula (15) and formula (16) applicable to the present invention are listed below, but the present invention is not limited thereto.

<Electron accepting compound>
It is preferable that the composition for forming a hole injection layer contains an electron-accepting compound as a constituent material of the hole injection layer 3.

The electron-accepting compound is preferably a compound that has oxidizing power and has the ability to accept one electron from the above-mentioned hole-transporting material. Specifically, as the electron-accepting compound, a compound having an electron affinity of 4.0 eV or more is preferable, and a compound having an electron affinity of 5.0 eV or more is more preferable.

Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples include one or more compounds selected from the following. More specifically, as electron-accepting compounds, onium salts substituted with organic groups (International Publication 2005/089024, International Publication No. 2017/164268); high-valent inorganic compounds such as iron(III) chloride (JP 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris( Examples include aromatic boron compounds such as (pentafluorophenyl)borane (JP 2003-31365A); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ion, alkylbenzene sulfonate ion, and camphor sulfonate ion.

The electron-accepting compound can improve the electrical conductivity of the hole-injecting layer 3 by oxidizing the hole-transporting material.

<Other constituent materials>
In addition to the hole transport material and electron-accepting compound described above, the material for the hole injection layer 3 may contain other components as long as the effects of the present invention are not significantly impaired.

<Solvent>
It is preferable that at least one of the solvents in the composition for forming a hole injection layer used in the wet film forming method is a compound that can dissolve the constituent material of the hole injection layer 3 described above.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents.

Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, Aromatic ethers such as phenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, 3-phenoxytoluene, diphenyl ether, dibenzyl ether, etc. .

Examples of ester solvents include phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, isobutyl benzoate, pentyl benzoate, isopentyl benzoate, methyl toluate, and toluic acid. Examples include aromatic esters such as ethyl, methyl anisate, ethyl anisate, dimethyl phthalate, diethyl phthalate, phenoxyethyl acetate, and phenoxyethyl butyrate.

Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, trimethylbenzene, tetramethylbenzene, diisopropylbenzene, triisopropylbenzene, methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, diisopropylnaphthalene, ethylbiphenyl, isopropylbiphenyl, and butyl. Examples include biphenyl, diisopropylbiphenyl, triisopropylbiphenyl, tetralin, 1,1-diphenylethane, 1,1-diphenylpropane, 1,1-diphenylbutane, 1,1 diphenylpentane, and 1,1-diphenylhexane.

Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.
In addition, dimethyl sulfoxide and the like can also be used.
Among them, aromatic esters and aromatic ethers are preferred.

One type of these solvents may be used alone, or two or more types may be used in any combination and ratio.

The concentration of the hole transport material in the composition for forming a hole injection layer is arbitrary as long as it does not significantly impair the effects of the present invention. The concentration of the hole transport material in the composition for forming a hole injection layer is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and even more preferably 0. .5% by weight or more. The concentration of the hole transport material in the composition for forming a hole injection layer is preferably 70% by weight or less, more preferably 60% by weight or less, even more preferably 50% by weight or less. This concentration is preferably small in that film thickness unevenness is less likely to occur. Further, this concentration is preferably large in that defects are less likely to occur in the formed hole injection layer.

<Formation of hole injection layer by wet film formation method>
When forming the hole injection layer 3 by a wet film forming method, the material constituting the hole injection layer 3 is usually mixed with an appropriate solvent (solvent for hole injection layer) to form a film forming composition ( A composition for forming hole injection layer 3 is prepared, and this composition for forming hole injection layer 3 is applied onto a layer corresponding to the lower layer of the hole injection layer (usually anode 2) by an appropriate method. The hole injection layer 3 is formed by forming a film and drying it.

[Hole transport layer]
The hole transport layer 4 is a layer that transports from the anode 2 to the light emitting layer 5. The hole transport layer 4 is not an essential layer for the organic electroluminescent device of the present invention, but when the hole transport layer 4 is provided, the hole transport layer 4 is usually formed when the hole injection layer 3 is provided. is formed on the hole injection layer 3, or on the anode 2 if there is no hole injection layer 3.

The method for forming the hole transport layer 4 may be a vacuum evaporation method or a wet film formation method, and is not particularly limited. The hole transport layer 4 is preferably formed by a wet film forming method from the viewpoint of reducing dark spots.

The material forming the hole transport layer 4 is preferably a material that has high hole transport properties and can efficiently transport injected holes. For this reason, the material forming the hole transport layer 4 has a low ionization potential, high transparency to visible light, high hole mobility, and excellent stability, so that impurities that can become traps are eliminated during manufacturing. It is preferable that it is unlikely to occur during use. In many cases, the hole transport layer 4 is in contact with the light-emitting layer 5, so it does not quench the light emitted from the light-emitting layer 5 or form an exciplex with the light-emitting layer 5, thereby reducing efficiency. preferable.

The material for the hole transport layer 4 may be any material that has been conventionally used as a constituent material for the hole transport layer 4. Examples of materials for the hole transport layer 4 include arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, and silole derivatives. , oligothiophene derivatives, fused polycyclic aromatic derivatives, metal complexes, and the like.

Examples of materials for the hole transport layer 4 include polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, and polyarylene vinylene. derivatives, polysiloxane derivatives, polythiophene derivatives, poly(p-phenylenevinylene) derivatives and the like. These may be alternating copolymers, random polymers, block polymers or graft copolymers. It may also be a polymer whose main chain is branched and has three or more terminal parts, or a so-called dendrimer.

Among these, as the material for the hole transport layer 4, polyarylamine derivatives and polyarylene derivatives are preferable.
Specific examples of polyarylamine derivatives and polyarylene derivatives include those described in JP-A No. 2008-98619.
As the polyarylamine derivative, it is preferable to use the aromatic tertiary amine polymer compound described above.

When forming the hole transport layer 4 by a wet film forming method, a composition for forming a hole transport layer is prepared in the same manner as in the formation of the hole injection layer 3 described above, and then dried after wet film formation.
The composition for forming a hole transport layer contains a solvent in addition to the hole transport material described above. The solvent used is the same as that used for the hole injection layer forming composition. Further, the film forming conditions, drying conditions, etc. are the same as those for forming the hole injection layer 3.
When the composition for forming a hole transport layer is the composition of the present invention, the solvents are the first solvent and the second solvent of the present invention.
When the hole transport layer 4 is formed by vacuum evaporation, the conditions for forming the film are the same as those for forming the hole injection layer 3 described above.

The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 300 nm or more, taking into consideration factors such as penetration of the low-molecular material in the light-emitting layer and swelling of the hole transport material. It is 200 nm or less.

[Light-emitting layer]
The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between the electrodes to which an electric field is applied, and becomes a main light emission source. Generally, the light-emitting layer 5 is on the hole-transporting layer 4 when there is the hole-transporting layer 4, and on the hole-injecting layer 3 when there is no hole-transporting layer 4 and when there is the hole-injecting layer 3. If neither the hole transport layer 4 nor the hole injection layer 3 is present on the anode 2, it is formed on the anode 2.

<Material for light emitting layer>
The material for the light emitting layer usually includes a light emitting material and a charge transport material serving as a host.

<Light-emitting material>
As the light-emitting material, any known material that is usually used as a light-emitting material for organic electroluminescent devices can be used, and there are no particular limitations, as long as it emits light at a desired emission wavelength and has good luminous efficiency. Just use substances. The luminescent material may be a fluorescent material or a phosphorescent material, but from the viewpoint of internal quantum efficiency, it is preferably a phosphorescent material. More preferably, the red-emitting material and the green-emitting material are phosphorescent materials, and the blue-emitting material is a fluorescent material.

When the composition of the present invention is a composition for forming a light-emitting layer, it is preferable to use the following phosphorescent materials, fluorescent materials, and charge transport materials.

<Phosphorescent material>
A phosphorescent material refers to a material that emits light from an excited triplet state. For example, a typical example is a metal complex compound containing Ir, Pt, Eu, etc., and the structure of the material preferably includes a metal complex.

Among metal complexes, phosphorescent organometallic complexes that emit light via the triplet state are known from the long period periodic table (hereinafter, unless otherwise specified, when we refer to the periodic table, we refer to the long period periodic table). ) Examples include Werner type complexes or organometallic complexes containing a metal selected from Groups 7 to 11 as a central metal. Examples of such phosphorescent materials include the phosphorescent materials described in International Publication No. 2014/024889, International Publication No. 2015-087961, International Publication No. 2016/194784, and JP2014-074000. Preferably, a compound represented by the following formula (201) or a compound represented by the following formula (205) is preferable, and a compound represented by the following formula (201) is more preferable.

In formula (201), ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
R ¹⁰¹ and R ¹⁰² are each independently a structure represented by formula (202), and "*" represents the bonding position with ring A1 or ring A2. R ¹⁰¹ and R ¹⁰² may be the same or different, and when a plurality of R ¹⁰¹ and R ¹⁰² exist, they may be the same or different.

Ar ²⁰¹ and Ar ²⁰³ each independently represent an aromatic hydrocarbon ring structure that may have a substituent or an aromatic heterocyclic structure that may have a substituent.
Ar ²⁰² is an aromatic hydrocarbon ring structure that may have a substituent, an aromatic heterocyclic structure that may have a substituent, or an aliphatic hydrocarbon structure that may have a substituent. represents.
Substituents bonded to ring A1, substituents bonded to ring A2, or substituents bonded to ring A1 and substituents bonded to ring A2 may bond to each other to form a ring.

B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond or an atomic group that constitutes a bidentate ligand together with B ²⁰¹ and B ²⁰² . When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² exist, they may be the same or different.

Note that in equations (201) and (202),
i1 and i2 each independently represent an integer between 0 and 12,
i3 represents an integer of 0 or more with an upper limit of the number that can be replaced with Ar ²⁰² ,
i4 represents an integer of 0 or more with an upper limit of the number that can be replaced with Ar ²⁰¹ ,
k1 and k2 each independently represent an integer of 0 or more with an upper limit of the number that can be substituted in ring A1 and ring A2,
z represents an integer from 1 to 3.

(substituent)
Unless otherwise specified, the substituent is preferably a group selected from the following substituent group S.

<Substituent group S>
・Alkyl group, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, still more preferably an alkyl group having 1 to 8 carbon atoms, particularly preferably an alkyl group having 1 to 6 carbon atoms .
-Alkoxy group, preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, still more preferably an alkoxy group having 1 to 6 carbon atoms.
-Aryloxy group, preferably an aryloxy group having 6 to 20 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, even more preferably an aryloxy group having 6 to 12 carbon atoms, particularly preferably an aryloxy group having 6 to 12 carbon atoms Aryloxy group.
- Heteroaryloxy group, preferably a heteroaryloxy group having 3 to 20 carbon atoms, more preferably a heteroaryloxy group having 3 to 12 carbon atoms.
- An alkylamino group, preferably an alkylamino group having 1 to 20 carbon atoms, more preferably an alkylamino group having 1 to 12 carbon atoms.
- An arylamino group, preferably an arylamino group having 6 to 36 carbon atoms, more preferably an arylamino group having 6 to 24 carbon atoms.
-Aralkyl group, preferably an aralkyl group having 7 to 40 carbon atoms, more preferably an aralkyl group having 7 to 18 carbon atoms, even more preferably an aralkyl group having 7 to 12 carbon atoms.
・Heteroaralkyl group, preferably a heteroaralkyl group having 7 to 40 carbon atoms, more preferably a heteroaralkyl group having 7 to 18 carbon atoms,
・Alkenyl group, preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, still more preferably an alkenyl group having 2 to 8 carbon atoms, particularly preferably an alkenyl group having 2 to 6 carbon atoms .
- An alkynyl group, preferably an alkynyl group having 2 to 20 carbon atoms, more preferably an alkynyl group having 2 to 12 carbon atoms.
-Aryl group, preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, still more preferably an aryl group having 6 to 18 carbon atoms, particularly preferably an aryl group having 6 to 14 carbon atoms .
・Heteroaryl group, preferably a heteroaryl group having 3 to 30 carbon atoms, more preferably a heteroaryl group having 3 to 24 carbon atoms, still more preferably a heteroaryl group having 3 to 18 carbon atoms, particularly preferably a heteroaryl group having 3 to 30 carbon atoms 14 heteroaryl groups.
- An alkylsilyl group, preferably an alkylsilyl group in which the alkyl group has 1 to 20 carbon atoms, more preferably an alkylsilyl group in which the alkyl group has 1 to 12 carbon atoms.
- An arylsilyl group, preferably an arylsilyl group in which the aryl group has 6 to 20 carbon atoms, more preferably an arylsilyl group in which the aryl group has 6 to 14 carbon atoms.
- An alkylcarbonyl group, preferably an alkylcarbonyl group having 2 to 20 carbon atoms.
-Arylcarbonyl group, preferably an arylcarbonyl group having 7 to 20 carbon atoms.

In the above groups, one or more hydrogen atoms may be replaced with a fluorine atom, or one or more hydrogen atoms may be replaced with a deuterium atom.
Unless otherwise specified, aryl is an aromatic hydrocarbon ring and heteroaryl is an aromatic heterocycle.
- Hydrogen atom, deuterium atom, fluorine atom, cyano group, or -SF ₅ .

Among the substituent group S, preferred are alkyl groups, alkoxy groups, aryloxy groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, heteroaryl groups, alkylsilyl groups, arylsilyl groups, and groups thereof. is a group in which one or more hydrogen atoms of is replaced with a fluorine atom, a fluorine atom, a cyano group, or _-SF5 ,
More preferred are alkyl groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, and heteroaryl groups, and groups in which one or more hydrogen atoms of these groups are replaced with fluorine atoms, fluorine atoms, cyano group, or _-SF5 ,
More preferred are alkyl groups, alkoxy groups, aryloxy groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, heteroaryl groups, alkylsilyl groups, and arylsilyl groups,
Particularly preferred are alkyl groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, and heteroaryl groups,
Most preferred are alkyl groups, arylamino groups, aralkyl groups, aryl groups, and heteroaryl groups.

These substituent groups S may further have substituents selected from the substituent groups S as substituents. Preferable groups, more preferable groups, still more preferable groups, particularly preferable groups, and most preferable groups of the substituents that may be present are the same as the preferable groups in substituent group S.

(Ring A1)
Ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.

The aromatic hydrocarbon ring is preferably an aromatic hydrocarbon ring having 6 to 30 carbon atoms. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring are preferred.

The aromatic heterocycle is preferably an aromatic heterocycle having 3 to 30 carbon atoms and containing any one of a nitrogen atom, an oxygen atom, or a sulfur atom as a hetero atom. More preferred are a furan ring, a benzofuran ring, a thiophene ring, and a benzothiophene ring.
Ring A1 is more preferably a benzene ring, a naphthalene ring, or a fluorene ring, particularly preferably a benzene ring or a fluorene ring, and most preferably a benzene ring.

(Ring A2)
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
The aromatic heterocycle is preferably an aromatic heterocycle having 3 to 30 carbon atoms and containing any one of a nitrogen atom, an oxygen atom, or a sulfur atom as a hetero atom. Specifically, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, Examples include naphthyridine ring and phenanthridine ring, preferably pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, benzothiazole ring, benzoxazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, and quinazoline ring, and more preferably is a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, or a quinazoline ring, most preferably a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, a quinoxaline ring, or a quinazoline ring. .

(Combination of ring A1 and ring A2)
Preferred combinations of ring A1 and ring A2, expressed as (ring A1-ring A2), are (benzene ring-pyridine ring), (benzene ring-quinoline ring), (benzene ring-quinoxaline ring), (benzene ring- (quinazoline ring), (benzene ring-benzothiazole ring), (benzene ring-imidazole ring), (benzene ring-pyrrole ring), (benzene ring-diazole ring), and (benzene ring-thiophene ring).

(Substituents on ring A1 and ring A2)
The substituents that ring A1 and ring A2 may have can be arbitrarily selected, but are preferably one or more substituents selected from the above substituent group S.

(Ar ²⁰¹ , Ar ²⁰² , Ar ²⁰³ )
Ar ²⁰¹ and Ar ²⁰³ each independently represent an aromatic hydrocarbon ring structure that may have a substituent or an aromatic heterocyclic structure that may have a substituent.
Ar ²⁰² is an aromatic hydrocarbon ring structure that may have a substituent, an aromatic heterocyclic structure that may have a substituent, or an aliphatic hydrocarbon structure that may have a substituent. represents.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is an aromatic hydrocarbon ring structure which may have a substituent, the aromatic hydrocarbon ring structure is preferably an aromatic hydrocarbon ring structure having 6 to 30 carbon atoms. It is a group hydrocarbon ring. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring are preferred, a benzene ring, a naphthalene ring, and a fluorene ring are more preferred, and a benzene ring is most preferred.

When either Ar ²⁰¹ or Ar ²⁰² is a benzene ring which may have a substituent, it is preferable that at least one benzene ring is bonded to an adjacent structure at the ortho or meta position, and at least one More preferably, two benzene rings are bonded to adjacent structures at meta positions.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is a fluorene ring that may have a substituent, the 9- and 9'-positions of the fluorene ring have a substituent or are bonded to adjacent structures. It is preferable that

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is an aromatic heterocyclic structure which may have a substituent, the aromatic heterocyclic structure preferably contains a nitrogen atom, an oxygen atom, or An aromatic heterocycle having 3 to 30 carbon atoms and containing any sulfur atom, specifically a pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring , a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, a phenanthridine ring, a carbazole ring, a dibenzofuran ring, and a dibenzothiophene ring, preferably a pyridine ring or a pyrimidine ring. , triazine ring, carbazole ring, dibenzofuran ring, and dibenzothiophene ring.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is a carbazole ring which may have a substituent, the N-position of the carbazole ring may have a substituent or be bonded to an adjacent structure. preferable.

When Ar ²⁰² is an aliphatic hydrocarbon structure that may have a substituent, it is an aliphatic hydrocarbon structure having a linear, branched, or cyclic structure, and preferably has 1 to 24 carbon atoms. More preferably, the number of carbon atoms is 1 or more and 12 or less, and more preferably 1 or more and 8 or less.

(i1, i2, i3, i4, k1, k2)
i1 and i2 each independently represent an integer of 0 to 12, preferably 1 to 12, more preferably 1 to 8, and even more preferably 1 to 6. By being within this range, it is expected that solubility and charge transport properties will be improved.
i3 preferably represents an integer of 0 to 5, more preferably 0 to 2, more preferably 0 or 1.
i4 preferably represents an integer of 0 to 2, more preferably 0 or 1.
k1 and k2 each independently preferably represent an integer of 0 to 3, more preferably 1 to 3, more preferably 1 or 2, particularly preferably 1.

(Preferred substituents for Ar ²⁰¹ , Ar ²⁰² , Ar ²⁰³ )
The substituents that Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ may have can be arbitrarily selected, but are preferably one or more substituents selected from the above substituent group S, and preferred groups are also the above substituents. As shown in group S, more preferred are unsubstituted (hydrogen atoms), alkyl groups, and aryl groups, particularly preferred are unsubstituted (hydrogen atoms), alkyl groups, and most preferred are unsubstituted (hydrogen atoms). ) or a tert-butyl group, where the tert-butyl group is substituted by Ar ²⁰³ when Ar ²⁰³ is present, Ar ²⁰² when Ar ²⁰³ is absent, and Ar ²⁰¹ when Ar ²⁰² and Ar ²⁰³ are absent. It is preferable that you do so.

(Preferred embodiment of the compound represented by formula (201))
The compound represented by formula (201) is preferably a compound that satisfies any one or more of the following (I) to (IV).

(I) Phenylene linked formula The structure represented by formula (202) is a structure having a group in which benzene rings are linked, that is, a benzene ring structure, i1 is 1 to 6, and at least one benzene ring is in the ortho or meta position. It is preferable that the structure is bonded to an adjacent structure at the position.
Such a structure is expected to improve solubility and charge transport properties.

(II) (phenylene)-aralkyl (alkyl)
A structure having an aromatic hydrocarbon group or an aromatic heterocyclic group to which an alkyl group or an aralkyl group is bonded to ring A1 or ring A2, that is, Ar ²⁰¹ is an aromatic hydrocarbon structure or an aromatic heterocyclic structure, and i1 is 1 ~6, Ar ²⁰² is an aliphatic hydrocarbon structure, i2 is 1 to 12, preferably 3 to 8, Ar ²⁰³ is a benzene ring structure, and i3 is 0 or 1, preferably Ar ²⁰¹ is the aromatic hydrocarbon structure It has a hydrogen structure, more preferably a structure in which 1 to 5 benzene rings are connected, and more preferably one benzene ring.
Such a structure is expected to improve solubility and charge transport properties.

(III) Dendron A structure in which a dendron is bonded to ring A1 or ring A2, for example, Ar ²⁰¹ and Ar ²⁰² are benzene ring structures, Ar ²⁰³ is a biphenyl or terphenyl structure, i1 and i2 are 1 to 6, i3 is 2, j is 2.
Such a structure is expected to improve solubility and charge transport properties.

(IV) B ²⁰¹ -L ²⁰⁰ -B ²⁰²
The structure represented by B ²⁰¹ -L ²⁰⁰ -B ²⁰² is preferably a structure represented by the following formula (203) or the following formula (204).

In formula (203), R ²¹¹ , R ²¹² , and R ²¹³ each independently represent a substituent.
In formula (204), ring B3 represents an aromatic heterocyclic structure containing a nitrogen atom, which may have a substituent. Ring B3 is preferably a pyridine ring.

(Preferred phosphorescent material)
The phosphorescent material represented by the above formula (201) is not particularly limited, but the following are preferred.

Further, a phosphorescent material represented by the following formula (205) is also preferable.

[In formula (205), M ² represents a metal, and T represents a carbon atom or a nitrogen atom. R ⁹² to R ⁹⁵ each independently represent a substituent. However, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. ]

In formula (205), specific examples of M ² include metals selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold is preferred, and divalent metals such as platinum and palladium are particularly preferred.

In addition, in formula (205), R ⁹² and R ⁹³ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, It represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group, or an aromatic heterocyclic group.

Further, when T is a carbon atom, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, when T is a nitrogen atom, R ⁹⁴ or R ⁹⁵ directly bonded to T does not exist. Furthermore, R ⁹² to R ⁹⁵ may further have a substituent. As the substituent, the above-mentioned substituents can be used. Furthermore, any two or more groups among R ⁹² to R ⁹⁵ may be linked to each other to form a ring.

(molecular weight)
The molecular weight of the phosphorescent material is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less. Further, the molecular weight of the phosphorescent material is preferably 800 or more, more preferably 1000 or more, still more preferably 1200 or more. It is considered that by having a molecular weight in this range, the phosphorescent materials do not aggregate with each other and are uniformly mixed with the charge transporting material, thereby making it possible to obtain a luminescent layer with high luminous efficiency.

The molecular weight of the phosphorescent material is high in Tg, melting point, decomposition temperature, etc., the phosphorescent material and the formed light emitting layer have excellent heat resistance, and the film quality due to gas generation, recrystallization, molecular migration, etc. A larger value is preferable in that it is less likely to cause a decrease in the concentration of impurities or an increase in impurity concentration due to thermal decomposition of the material. On the other hand, the molecular weight of the phosphorescent material is preferably small in terms of ease of purification of the organic compound.

<Charge transport material>
The charge transport material used in the light emitting layer is a material having a skeleton with excellent charge transport properties, and may be selected from electron transport materials, hole transport materials, and bipolar materials capable of transporting both electrons and holes. preferable.

Specific examples of skeletons with excellent charge transport properties include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, benzylphenyl structures, Examples include a fluorene structure, a quinacridone structure, a triphenylene structure, a carbazole structure, a pyrene structure, an anthracene structure, a phenanthroline structure, a quinoline structure, a pyridine structure, a pyrimidine structure, a triazine structure, an oxadiazole structure, and an imidazole structure.

As the electron-transporting material, compounds having a pyridine structure, a pyrimidine structure, or a triazine structure are more preferable from the viewpoint of being a material with excellent electron-transporting properties and a relatively stable structure. is even more preferable.

The hole-transporting material is a compound having a structure with excellent hole-transporting properties, and among the central skeletons with excellent charge-transporting properties, a carbazole structure, a dibenzofuran structure, a triarylamine structure, a naphthalene structure, a phenanthrene structure, or A pyrene structure is preferred as a structure with excellent hole transport properties, and a carbazole structure, dibenzofuran structure, or triarylamine structure is more preferred.

The charge transport material used in the light emitting layer preferably has a fused ring structure of 3 or more rings, and is a compound having two or more fused ring structures of 3 or more rings or a compound having at least one fused ring of 5 or more rings. is even more preferable. These compounds increase the rigidity of molecules, making it easier to obtain the effect of suppressing the degree of molecular motion in response to heat. Further, the fused rings of 3 or more rings and the fused rings of 5 or more rings preferably have an aromatic hydrocarbon ring or an aromatic heterocycle from the viewpoint of charge transportability and material durability.

Specifically, the fused ring structure of three or more rings includes an anthracene structure, a phenanthrene structure, a pyrene structure, a chrysene structure, a naphthacene structure, a triphenylene structure, a fluorene structure, a benzofluorene structure, an indenofluorene structure, an indrofluorene structure, Examples include a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure. From the viewpoint of charge transport properties and solubility, at least one selected from the group consisting of a phenanthrene structure, a fluorene structure, an indenofluorene structure, a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure. Preferably, a carbazole structure or an indolocarbazole structure is more preferable from the viewpoint of durability against charges.

In the present invention, from the viewpoint of durability against charges of the organic electroluminescent device, it is preferable that at least one of the charge transport materials in the light emitting layer is a material having a pyrimidine skeleton or a triazine skeleton.

The charge transport material of the light emitting layer is preferably a polymer material from the viewpoint of excellent flexibility. A light-emitting layer formed using a material with excellent flexibility is preferable as a light-emitting layer of an organic electroluminescent device formed on a flexible substrate. When the charge transporting material contained in the light-emitting layer is a polymeric material, the molecular weight is preferably 5,000 or more and 1,000,000 or less, more preferably 10,000 or more and 500,000 or less, and even more preferably 10,000 or more and 500,000 or less. 000 or more and 100,000 or less.

In addition, the charge transport material for the light emitting layer should be selected from the viewpoints of ease of synthesis and purification, ease of designing electron transport performance and hole transport performance, and ease of adjusting viscosity when dissolved in a solvent. Preferably, it is a low molecule. When the charge transport material contained in the light emitting layer is a low molecular weight material, the molecular weight is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less, and most preferably 2,000 or less. ,000 or less, preferably 300 or more, more preferably 350 or more, still more preferably 400 or more.

<Fluorescent material>
The fluorescent material is not particularly limited, but a compound represented by the following formula (211) is preferred.

In the above formula (211), Ar ²⁴¹ represents an aromatic hydrocarbon condensed ring structure which may have a substituent, Ar ²⁴² and Ar ²⁴³ each independently an alkyl group which may have a substituent, Represents an aromatic hydrocarbon group, an aromatic heterogroup, or a group in which these are bonded. n41 is an integer from 1 to 4.

Ar ²⁴¹ preferably represents an aromatic hydrocarbon condensed ring structure having 10 to 30 carbon atoms, and specific ring structures include naphthalene, acenaphthene, fluorene, anthracene, phenathrene, fluoranthene, pyrene, tetracene, chrysene, perylene, etc. Can be mentioned.
Ar ²⁴¹ is more preferably an aromatic hydrocarbon condensed ring structure having 12 to 20 carbon atoms, and specific ring structures include acenaphthene, fluorene, anthracene, phenathrene, fluoranthene, pyrene, tetracene, chrysene, and perylene. .
Ar ²⁴¹ is more preferably an aromatic hydrocarbon condensed ring structure having 16 to 18 carbon atoms, and specific examples of the ring structure include fluoranthene, pyrene, and chrysene.

n41 is 1 to 4, preferably 1 to 3, more preferably 1 to 2, and most preferably 2.

The alkyl group for Ar ²⁴² and Ar ²⁴³ is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.
The aromatic hydrocarbon group for Ar ²⁴² and Ar ²⁴³ is preferably an aromatic hydrocarbon group having 6 to 30 carbon atoms, more preferably an aromatic hydrocarbon group having 6 to 24 carbon atoms, and most preferably a phenyl group. , is a naphthyl group.
The aromatic heterogroup of Ar ²⁴² and Ar ²⁴³ is preferably an aromatic heterogroup having 3 to 30 carbon atoms, more preferably an aromatic hydrocarbon group having 5 to 24 carbon atoms, specifically a carbazolyl group, A dibenzofuranyl group and a dibenzothiophenyl group are preferred, and a dibenzofuranyl group is more preferred.

The substituent that Ar ²⁴¹ , Ar ²⁴² , and Ar ²⁴³ may have is preferably a group selected from the substituent group S, more preferably a hydrocarbon group included in the substituent group S, and even more preferably is a hydrocarbon group among the groups preferable as the substituent group S.

The charge transport material used together with the fluorescent material is not particularly limited, but is preferably one represented by the following formula (212).

In the above formula (212), R ²⁵¹ and R ²⁵² are each independently a structure represented by formula (213), and R ²⁵³ represents a substituent, and when there is a plurality of R ²⁵³ , they may be the same or different. and n43 is an integer from 0 to 8.

In the above formula (213), * represents a bond with the anthracene ring of formula (212), and Ar ²⁵⁴ and Ar ²⁵⁵ each independently represent an aromatic hydrocarbon structure that may have a substituent, or a substituted Represents a heteroaromatic ring structure which may have a group, Ar ²⁵⁴ and Ar ²⁵⁵ each may be the same or different when there is a plurality of them, n44 is an integer of 1 to 5, and n45 is 0 to 5. It is an integer of 5.

Ar ²⁵⁴ is preferably a monocyclic or fused ring aromatic hydrocarbon structure having 6 to 30 carbon atoms, which may have a substituent, and more preferably has a substituent. , a monocyclic or fused ring aromatic hydrocarbon structure having 6 to 12 carbon atoms.

Ar ²⁵⁵ is preferably a monocyclic or fused ring aromatic hydrocarbon structure having 6 to 30 carbon atoms, which may have a substituent, or an aromatic hydrocarbon structure having 6 to 30 carbon atoms, which may have a substituent. It is an aromatic heterocyclic structure that is a condensed ring of. Ar ²⁵⁵ is more preferably a monocyclic or fused ring aromatic hydrocarbon structure having 6 to 12 carbon atoms, which may have a substituent, or an aromatic hydrocarbon structure having 12 carbon atoms, which may have a substituent. It is an aromatic heterocyclic structure that is a fused ring.

n44 is preferably an integer of 1 to 3, more preferably 1 or 2.
n45 is preferably an integer of 0 to 3, more preferably 0 to 2.

The substituent that R ²⁵³ , Ar ²⁵⁴ and Ar ²⁵⁵ may have is preferably a group selected from the above-mentioned substituent group S. More preferably, it is a hydrocarbon group included in the substituent group S, and still more preferably a hydrocarbon group among the groups preferable as the substituent group S.

The molecular weight of the fluorescent material and the charge transport material is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less, and most preferably 2,000 or less. Moreover, it is preferably 300 or more, more preferably 350 or more, and still more preferably 400 or more.

[Hole blocking layer]
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8, which will be described later. The hole blocking layer 6 is a layer of the electron transport layer that also plays the role of blocking holes moving from the anode 2 from reaching the cathode 9. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

The hole blocking layer 6 has the roles of blocking holes moving from the anode 2 from reaching the cathode 9 and efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. have

The physical properties required of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet energy level (T1 ) is high. Examples of materials for the hole blocking layer 6 that meet these conditions include bis(2-methyl-8-quinolinolato)(phenolato)aluminum, bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum, etc. mixed ligand complexes, metal complexes such as bis(2-methyl-8-quinolato)aluminum-μ-oxo-bis-(2-methyl-8-quinolinolato)aluminum dinuclear metal complexes, distyrylbiphenyl derivatives, etc. Styryl compounds (JP-A-11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5(4-tert-butylphenyl)-1,2,4-triazole (JP-A-7 -41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Application Laid-Open No. 10-79297). Furthermore, a compound having at least one pyridine ring substituted at the 2, 4, and 6 positions described in International Publication No. 2005/022962 is also preferable as a material for the hole blocking layer 6.

There are no restrictions on the method of forming the hole blocking layer 6. The hole blocking layer 6 can be formed by a wet film formation method, a vapor deposition method, or other methods.
The thickness of the hole blocking layer 6 is arbitrary as long as it does not significantly impair the effects of the present invention. The thickness of the hole blocking layer 6 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[Electron transport layer]
The electron transport layer 7 is a layer provided between the light emitting layer 5 and the cathode 9 for transporting electrons.

The electron transport material for the electron transport layer 7 is usually one that has high electron injection efficiency from the cathode 9 or an adjacent layer on the cathode 9 side, has high electron mobility, and can efficiently transport the injected electrons. Use compounds that can be used. Compounds that satisfy these conditions include, for example, metal complexes such as aluminum complexes and lithium complexes of 8-hydroxyquinoline (Japanese Patent Application Laid-open No. 194393/1983), metal complexes of 10-hydroxybenzo[h]quinoline, and oxadioxide. Azole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N,N'-dicyanoanthraquinone diimine, triazine compound derivative, n-type hydrogen Examples include amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

The electron transport material used in the electron transport layer 7 includes electron transport organic compounds such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and metal complexes such as an aluminum complex of 8-hydroxyquinoline, as well as sodium, potassium, and cesium. By doping with alkali metals such as lithium, rubidium, etc. (described in JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.), excellent film quality and electron injection transport properties can be achieved. This is preferable because it makes it possible to achieve both. It is also effective to dope the above-mentioned electron-transporting organic compound with an inorganic salt such as lithium fluoride or cesium carbonate.

There are no restrictions on the method for forming the electron transport layer 7. The electron transport layer 7 can be formed by a wet film formation method, a vapor deposition method, or other methods.

The thickness of the electron transport layer 7 is arbitrary as long as it does not significantly impair the effects of the present invention. The thickness of the electron transport layer 7 is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[Electron injection layer]
In order to efficiently inject electrons injected from the cathode 9 into the light emitting layer 5, an electron injection layer 8 may be provided between the electron transport layer 7 and the cathode 9, which will be described later. The electron injection layer 8 is made of inorganic salt or the like.

Examples of materials for the electron injection layer 8 include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium (II) carbonate (CsCO ₃ ), etc. (Applied Physics Letters , 1997, Vol. 70, pp. 152; JP-A-10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc. ).

Since the electron injection layer 8 often does not have charge transport properties, in order to efficiently inject electrons, it is preferable to use it as an extremely thin film, and the film thickness is usually 0.1 nm or more, preferably 5 nm or less. be.

[cathode]
The cathode 9 is an electrode that serves to inject electrons into the layer on the light emitting layer 5 side.

The materials for the cathode 9 are usually metals such as aluminum, gold, silver, nickel, palladium, and platinum, metal oxides such as indium and/or tin oxides, metal halides such as copper iodide, carbon black, Alternatively, conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline may be used. Among these, metals with a low work function are preferred in order to efficiently inject electrons, and suitable metals such as tin, magnesium, indium, calcium, aluminum, silver, or alloys thereof are used. Specific examples include alloy electrodes with low work functions such as magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy, and the like.

Only one type of material may be used for the cathode 9, or two or more types may be used in combination in any combination and ratio.

The film thickness of the cathode 9 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the cathode 9 is usually about 5 nm or more, preferably about 10 nm or more, and usually about 1000 nm or less, preferably about 500 nm or less. The thickness of the cathode 9 may be arbitrary as long as it is opaque, and the cathode may be the same as the substrate.

It is also possible to layer different conductive materials on the cathode 9.
For the purpose of protecting the cathode, which is made of low work function metals such as alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium, the It is preferable to stack metal layers because this increases the stability of the device. Metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used for this purpose. These materials may be used alone or in any combination and ratio of two or more.

[Other layers]
The organic electroluminescent device of the present invention may have another configuration without departing from the spirit thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and layers that are not essential among the layers described above may be included. May be omitted.

Furthermore, the cathode 9 may have one or more organic layers on top of the cathode 9 as a protective layer for the cathode.

In the layered structure described above, it is also possible to laminate components other than the substrate in the reverse order. For example, with the layer configuration shown in FIG. The injection layer 3 and the anode 2 may be provided in this order.

The organic electroluminescent device of the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array, and the anode and cathode are It may also be applied to a configuration arranged in a Y matrix.

Each layer described above may contain components other than those described as materials, as long as the effects of the present invention are not significantly impaired.

[Organic electroluminescent device]
Two or more organic electroluminescent elements that emit light in different colors can be provided to provide an organic electroluminescent device such as an organic EL display device or an organic EL lighting device. In this organic electroluminescent device, by using at least one, preferably all the organic electroluminescent elements as the organic electroluminescent element of the present invention, a high quality organic electroluminescent device can be provided.

[Organic EL display device]
There are no particular limitations on the type or structure of an organic EL display device using the organic electroluminescent device of the present invention, and it can be assembled using the organic electroluminescent device of the present invention according to a conventional method.
For example, an organic EL display device can be formed by the method described in "Organic EL Display" (Ohmsha, published August 20, 2004, written by Shizushi Tokito, Chinaya Adachi, and Hideyuki Murata). can.

[Organic EL lighting]
There are no particular restrictions on the type or structure of organic EL lighting using the organic electroluminescent device of the present invention, and it can be assembled using the organic electroluminescent device of the present invention according to a conventional method.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the following examples, and the present invention can be implemented with arbitrary changes without departing from the gist thereof.

[Measurement of contact angle]
<Preparation of liquid repellent resist>
Hereinafter, the photosensitive resin composition of the present invention will be described with reference to specific examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Using each component in the proportions listed in Table 1, and using propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether so that the total solid content is 19% by mass, each component is mixed until uniform. By stirring, photosensitive liquid-repellent resists for Examples and Comparative Examples were prepared. In addition, the blending ratio (weight %) of each component in Table 1 means the value of the solid content of each component in the total solid content.

Photoinitiator a-1: A compound having the following chemical structure.

Alkali-soluble resin b1: ZCR-8029 (manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight Mw = 6640, acid value = 62 mgKOH/g). Note that this resin b1 corresponds to epoxy (meth)acrylate resin (B1).
Resin b-1 has a partial structure represented by the following formula.

Alkali-soluble resin b-2: ZAR-1872 (manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight Mw = 8000, acid value = 80 mgKOH/g). Note that this resin b-2 corresponds to epoxy (meth)acrylate resin (B1).
Resin b-2 has a partial structure represented by the following formula.

* in the above formula represents a monovalent group represented by the following formula or a bond with a hydrogen atom.

Photopolymerizable compound c-1: Pentaerythritol tetraacrylate manufactured by Kyoeisha Chemical Co., Ltd.
Liquid repellent d-1: an acrylic copolymer resin having a constitutional unit having a perfluoroalkyl group, a constitutional unit having an ethylenic double bond, and a constitutional unit having a carboxyl group. Mw 90000, fluorine atom content 20% by mass.
Additive e-1: KAYAMER PM-21 manufactured by Nippon Kayaku Co., Ltd.
Additive f-1: Methylhydroquinone having the following structural formula.

<Fabrication of liquid-repellent resist film>
A glass substrate with a reflective film was manufactured by laminating 10 nm of indium tin oxide (ITO), 100 nm of silver palladium copper (APC) alloy, and 10 nm of ITO on a 0.7 mm thick glass plate using a sputtering method. . The substrate was cut into a size of 100 mm x 100 mm, and the liquid-repellent resist was coated on the reflective film side using a spin coat spinner so that the film thickness after curing would be 1.5 μm. Thereafter, a drying process was performed for 60 seconds using a vacuum dryer. Subsequently, it was heated and dried for 120 seconds on a hot plate heated to 115°C. The obtained film was exposed to light without using a photomask. Using a mirror projection type exposure machine (MPA-600FA) manufactured by Canon Inc., exposure was performed for 35 seconds so that the exposure amount was 140 mJ/cm ² . The illuminance was 500 mW/ ^cm2 .
Subsequently, spray development was performed for 60 seconds with a 2.38 mass % TMAH (tetramethylammonium hydroxide) aqueous solution at 24° C., and then washed with pure water for 1 minute. Thereafter, it was baked in an oven heated to 230° C. for 30 minutes to form a liquid-repellent resist film.

<Removal of surface liquid repellent component>
The outermost surface of the liquid-repellent resist film was surface-treated using a plasma surface treatment device to remove the liquid-repellent agent present on the outermost surface, and a pseudo bank side surface was created on the substrate. The plasma treatment was performed using a small plasma cleaner PDC-32G (Harrick Plasma). The degree of vacuum in the plasma treatment was 140 to 160 Pa, the atmospheric pressure was approximately 40 sccm, the RF power was 18 W, and the treatment time was 30 seconds. Here, a film obtained by removing the liquid repellent from the surface of the liquid repellent resist film is referred to as a pseudo bank side film.

<Measurement of contact angle>
The contact angles of various solvents were measured on the pseudo bank side film. The contact angle was measured using DMо-501 manufactured by Kyowa Interface Science, and the liquid volume was set at 1.0 μL. The contact angles of various solvents are summarized in Table 2.

[Evaluation of flatness of functional film]
Next, the flatness when ink is applied to a region divided by banks and dried will be described with reference to examples.

[Example 1]
<Preparation of functional ink>
A polymer compound (P-1) shown by the following structural formula (weight average molecular weight: about 15,000) and an electron-accepting compound (HI-1) shown by the following structural formula in weight ratio (P-1) :(HI-1)=87:13 using an electronic balance, which was designated as hole injection material 1. Next, ethyl-4-methylbenzoate (boiling point: about 232°C, vapor pressure: about 6.6 Pa) and 2,7-diisopropylnaphthalene (boiling point: about 306°C, vapor pressure: about 0.19 Pa) were mixed in a weight ratio of 75 :25 ratio to obtain a mixed solvent 1. Mix hole injection material 1 with mixed solvent 1 to a concentration of 2.0% by weight in a screw vial, then place the screw vial together in a vacuum chamber, repeat evacuation and nitrogen purge three times, and remove the screw vial. The gas inside was replaced with nitrogen. Thereafter, the mixture was heated at a hot plate temperature of 110° C. for 3 hours while stirring at 420 rpm using a magnetic stirrer. After the obtained composition was cooled to about room temperature, it was filtered using a membrane filter with a pore size of 0.2 μm to obtain Functional Ink 1.

<Preparation of the board>
An indium-tin oxide (ITO) film, a silver-indium compound film, and an indium-tin oxide film were sequentially formed by sputtering on a glass substrate with a film thickness of 0.5 mm, and electrodes were formed by general photolithography. formed a pattern. The liquid-repellent resist used when producing the pseudo-bank side film was applied onto the substrate so that the film thickness after curing would be 1.5 μm. Thereafter, a drying process was performed for 60 seconds using a vacuum dryer. Subsequently, it was heated and dried for 120 seconds on a hot plate heated to 115°C. The obtained coating film was exposed to light using a photomask. Using a mirror projection type exposure machine (MPA-600FA) manufactured by Canon Inc., exposure was performed for 35 seconds so that the exposure amount was 140 mJ/cm2. The illuminance was 500 mW/cm2. The size of the openings of the photomask is 210 μm in the long axis, 90 μm in the short axis, and 45 μm in the corner R. There are 67 openings in the short axis direction and 21 in the long axis direction, for a total of 1407 openings. There is. Next, spray development was performed for 60 seconds with a 2.38% by weight TMAH (tetramethylammonium hydroxide) aqueous solution at 24° C., followed by washing with pure water for 1 minute. Through these operations, unnecessary portions were removed and the patterned substrate was cured by heating at 230° C. for 30 minutes in an oven to obtain a patterned liquid-repellent resist film.

The obtained substrate was placed in ultrapure water and subjected to ultrasonic cleaning for 15 minutes, and then dried for 10 minutes in a clean oven preheated to 130°C. Immediately before applying the composition, a step of baking on a hot plate heated to 230° C. for 10 minutes is performed to remove moisture adhering to the surface.

<Application of functional ink>
Functional ink 1 is filled into an inkjet printer cartridge (DMCLCP-11610, manufactured by Fujifilm) using a micropipette, and applied to the opening of the substrate using an inkjet printer (DMP-2831, manufactured by Fujifilm). did. The ejection voltage of the inkjet printer was adjusted so that the amount of each droplet of functional ink ejected from the nozzle of the inkjet head was 10 pL, and 7 drops were applied to each opening. The coating area is 55 in the minor axis direction and 20 in the major axis direction, for a total of 1,100 openings, and then the following drying and firing steps are performed.

<Drying, firing>
The obtained coating film is placed in a sealed chamber with an openable lid and heated to 0.1 Pa or less using a multi-stage pump (VMR-050 manufactured by ULVAC) that combines a mechanical booster pump and rotary pump oil. The membrane was dried under reduced pressure until it reached a pressure of .

In the vacuum drying, the pressure was first reduced from atmospheric pressure to 1 to 10 Pa over 240 seconds, and then reduced to 0.1 Pa or less over 180 seconds to volatilize the solvent component in the functional ink and form a functional film. .

The functional film was placed on a hot plate heated to 230° C. and baked for 30 minutes to obtain a functional film 1.

<Evaluation of functional membrane>
The film thickness profile of the obtained functional film was measured in the short axis direction of the opening using a palpable step gauge (Kosaka Institute ET-100). The flatness U of the measured film thickness profile was calculated using the following equation (1), and the flatness of the functional film 1 was evaluated.
U=LF/LB×100(%) (1)
However, LB represents the length of the opening of the bank, and LF represents the length (region) of the functional film having a film thickness that is not larger than the average film thickness of the measured film thickness profile by 15 nm or more. The flatness U of the functional film 1 was 96.6%.

[Example 2]
The mixed solvent 1 used in Example 1 was mixed with ethyl-4-methylbenzoate (boiling point: about 232°C, vapor pressure: about 6.6 Pa) and 4-butylbiphenyl (boiling point: about 318°C, vapor pressure: about 0.6 Pa). 08Pa) was changed to mixed solvent 2 in a weight ratio of 75:25, and the flatness U was calculated in the same manner as in Example 1, and the flatness U was 99. It was 3%.

[Example 3]
Mixed solvent 1 used in Example 1 was mixed with ethyl-4-methylbenzoate (boiling point: approximately 232°C, vapor pressure: approximately 6.6 Pa) and 1,1-diphenylpentane (boiling point: approximately 307°C, vapor pressure: approximately 0.17 Pa) was changed to mixed solvent 3 in a weight ratio of 75:25, and the flatness U was calculated in the same manner as in Example 1, and the flatness U was It was 94.6%.

[Comparative example 1]
Mixed solvent 1 used in Example 1 was mixed with ethyl-4-methylbenzoate (boiling point: about 232°C, vapor pressure: about 6.6 Pa) and benzyltoluene (boiling point: about 286°C, vapor pressure: about 0.62 Pa). When the flatness U was calculated by changing to mixed solvent 5 in a weight ratio of 75:25 and performing the same procedure as in Example 1, the flatness U was 65.8%. was.

[Comparative example 2]
The mixed solvent 1 used in Example 1 was changed to a single solvent of ethyl-4-methylbenzoate (boiling point: about 232°C, vapor pressure: about 6.6 Pa), and the process was carried out in the same manner as in Example 1. When the flatness U was calculated, the flatness U was 75.9%.

Table 3 summarizes the flatness U of the film and the profile of the film in the short axis direction of the above examples and comparative examples.

As is clear from the results, the flatness U is 90% or more in the functional ink containing an organic solvent that exhibits a contact angle with the pseudo bank side substrate of 26° or more and 50° or less. It is thought that this is because it has an appropriate contact angle with the side surface of the bank, so that it can properly wet down without self-pinning, resulting in a high degree of flatness.

Although the invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various changes can be made without departing from the spirit and scope of the invention.

1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent element

Claims (11)

a step of applying a liquid-repellent resist on a glass substrate having a conductive electrode pattern and forming a plurality of openings in minute regions by photolithography;
applying a functional ink containing at least one functional material and at least one organic solvent to the opening by a printing method;
Volatizing the organic solvent contained in the functional ink by drying under reduced pressure;
A method for producing an organic electroluminescent device comprising, in this order, the step of sintering the film obtained by the vacuum drying at a temperature of 150° C. or higher to obtain a functional film,
The organic solvent having a contact angle of 26° or more and less than 50° is applied to a film for contact angle measurement from which the surface of the lyophobic resist film obtained by curing the lyophobic resist is peeled off by external energy. A method for producing an organic electroluminescent device, the method including a solvent. 2. The method for manufacturing an organic electroluminescent device according to claim 1, wherein the surface of the liquid-repellent resist film is peeled off by external energy by UV/ozone treatment or plasma treatment. The method for manufacturing an organic electroluminescent device according to claim 1 or 2, wherein the organic solvent having a contact angle of 26° or more and less than 50° has the highest boiling point of all organic solvents contained in the functional ink. . Any one of claims 1 to 3, wherein the content of the organic solvent having a contact angle of 26° or more and less than 50° is 15% by weight or more based on all organic solvents contained in the functional ink. A method for manufacturing an organic electroluminescent device according to . Any one of claims 1 to 4, wherein the content of the organic solvent having a contact angle of 26° or more and less than 50° is less than 50% by weight based on all organic solvents contained in the functional ink. A method for manufacturing an organic electroluminescent device according to . The difference between the boiling point of the organic solvent having a contact angle of 26° or more and less than 50° and the boiling point of the organic solvent having the lowest boiling point among all the organic solvents contained in the functional ink is 20°C or more. A method for producing an organic electroluminescent device according to any one of Items 1 to 5. The method for producing an organic electroluminescent device according to any one of claims 1 to 6, wherein the functional material contains at least one hole-transporting compound and at least one electron-accepting compound. The method for producing an organic electroluminescent device according to any one of claims 1 to 7, wherein the organic solvent contained in the functional ink is dried under reduced pressure for 1 minute or more and less than 15 minutes. The method for manufacturing an organic electroluminescent device according to any one of claims 1 to 8, wherein the liquid-repellent resist contains a fluorine atom-containing resin. The method for manufacturing an organic electroluminescent device according to any one of claims 1 to 9, wherein the time for treating the liquid-repellent resist film with the external energy is 30 seconds or more and 300 seconds or less. An organic electroluminescent device manufactured using the manufacturing method according to any one of claims 1 to 10.

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