Method for producing organic electroluminescent element, and organic electroluminescent element

Abstract

The present invention addresses the problem of improving the uniformity of the film thickness in a region surrounded by a barrier when a functional film constituting an organic electroluminescent element is formed by wet film formation. The present invention relates to a method for manufacturing an organic electroluminescent element, the method comprising the following steps in this order: a step for providing openings of a plurality of minute regions by a predetermined method; a step for applying a predetermined functional ink to the opening by a printing method; and a step in which the organic solvent contained in the functional ink is volatilized by drying under reduced pressure, [theta] 1 is the contact angle between a liquid-repellent resist film obtained by curing a liquid-repellent resist and a solvent having the highest boiling point among all organic solvents contained in the functional ink, and [theta] 1 is the contact angle between the films for contact angle measurement after the surface of the liquid-repellent resist film is peeled off by external energy; when the taper angle of a bank formed by the liquid-repellent resist so as to surround the opening is set as [theta] 2, a predetermined relationship is satisfied.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an organic electroluminescent element and an organic electroluminescent element manufactured using the method. Background Art

[0002] Organic electroluminescent devices are typically manufactured by forming films of organic materials using vacuum deposition and then laminating them. In recent years, wet film formation, which involves forming films of organic materials in solution using methods such as inkjet and then laminating them, has been actively studied as a manufacturing method with higher material efficiency.

[0003] In the manufacture of organic electroluminescent elements, particularly organic EL displays, using wet film formation, research is underway to form films by dispensing inkjet ink, a composition for forming functional films that constitute the organic electroluminescent element, into microscopic regions within the banks, where each pixel is partitioned by partitions called banks. At this time, a technique has been proposed to achieve a flatter film within the regions enclosed by the banks by mixing various surface modifiers into the ink (Patent Documents 1 and 2).

[0004] However, in the conventional method, the flatness of the film in the region surrounded by the banks is not sufficient.

[0005] Patent Document 3 discloses a technique of using two or more solvents having different boiling points for the purpose of forming a functional layer having a substantially flat cross-sectional shape after drying and curing.

[0006] Particularly when using an inkjet device etc. and applying ink to the area divided by the dam (partition wall) for film formation, after making the dam itself have liquid repellency and the ink does not overflow to the outside of the dam, a sufficient amount of ink is applied to wet the entire area of ​​the divided area, and then various drying methods such as reduced pressure drying are used to volatilize the solvent component and obtain a functional film. When the ink in the divided area dries, the end of the ink gradually retreats on the dam side, and the concentration gradually increases, eventually becoming a functional film. However, due to the self-pinning phenomenon that stops midway on the dam side due to the difference in wettability of the dam side or the shape change of the dam side, the ink end sometimes cannot fully retreat on the dam side. When self-pinning occurs on the way to the dam side like this, the functional film thus made will present a shape that wets and climbs along the dam side, so that the film thickness is difficult to become uniform.

[0007] Self-pinning can be confirmed by measuring the receding contact angle of the ink against the bank side. However, there are issues with measuring the receding contact angle on the bank side, which has complex structures and surface properties, and controlling this angle is difficult. Furthermore, as the concentration of the drying ink increases during the drying process, its viscosity also increases, causing the ink to lose its fluidity and thus self-pinning.

[0008] In addition, the main reasons for the flow inside the droplet during the drying process include flow caused by non-uniform evaporation rate distribution, flow caused by changes in contact angle, and flow caused by surface tension distribution, which plays an important role in controlling the shape of functional films (H.Ishizuka, J.Fukai, Experiments in Fluids, 59, 4, 1-11, 2018) (J.Fukai, T.Harada, H.Ishizuka, Journal of Chemical Engineering of Japan, 52, 6, 484-492, 2019) (J.Fukai, J.Jpn.Colour Mater., 94, 4, 112-116, 2021). The drying rate distribution on the droplet surface has a distribution corresponding to the contact angle, which will cause flow inside the droplet in a system of multiple mixed solvents with different boiling points and surface tensions. The evaporation rate distribution of a droplet added to a solid-liquid interface with a contact angle of 90° is uniform. However, when the contact angle increases or decreases from 90°, the drying rate distribution becomes non-uniform, generating a flow caused by the non-uniform evaporation rate distribution. Prior art literature Patent Literature

[0009] Patent Document 1: International Publication No. 2010 / 104183 Patent Document 2: Japanese Patent Application Laid-Open No. 2002-056980 Patent Document 3: Japanese Patent Application Laid-Open No. 2015-185640 Summary of the Invention Problems to be solved by the invention

[0010] An object of the present invention is to improve the uniformity of film thickness within a region surrounded by banks when forming a functional film constituting an organic electroluminescent element by wet film formation. Technical solutions to the problem

[0011] The inventors discovered that the difference between the contact angle of the surface after the outermost surface of the bank is removed by treating the outermost surface with external energy and the taper angle of the lyophobic bank is correlated with the film shape of the functional layer. Specifically, they discovered that by forming a functional film using a combination of an ink containing a solvent that keeps the difference between the contact angle and the taper angle within a certain range, self-pinning and flow caused by a non-uniform evaporation rate distribution can be appropriately suppressed, resulting in a uniform film.

[0012] That is, the present invention has the following configuration.

[0013] A first embodiment of the present invention is a method for manufacturing an organic electroluminescent element, comprising the following steps in sequence: A process of coating a liquid-repellent resist on a substrate having a conductive electrode pattern and forming a plurality of openings in microscopic regions by photolithography; The step of applying a functional ink comprising at least one functional material and at least one organic solvent to the opening by a printing method; a step of volatilizing the organic solvent contained in the functional ink by drying under reduced pressure, The surface of the lyophobic resist film obtained by curing the lyophobic resist is peeled off by external energy to obtain a film for contact angle measurement. When the contact angle between the solvent with the highest boiling point among all organic solvents contained in the functional ink and the film for contact angle measurement is defined as θ1, and the taper angle of the bank formed by the lyophobic resist so as to surround the opening is defined as θ2, the following relationship is satisfied: -8°<θ2-θ1<45°.

[0014] A second aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to the first aspect, wherein: The functional ink comprises at least two organic solvents.

[0015] A third aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to the first or second aspect, wherein: The taper angle θ2 is greater than 30° and less than 70°, and the height of the bank is less than or equal to 1.9 μm.

[0016] A fourth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 3, wherein: The contact angle θ1 is greater than 0° and less than 78°.

[0017] A fifth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 4, wherein: The surface of the lyophobic resist film is peeled off by the external energy by UV / ozone treatment or plasma treatment.

[0018] A sixth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 5, wherein: The content of the organic solvent having the contact angle θ1 is 5% by weight or more relative to the total weight of all organic solvents contained in the functional ink.

[0019] A seventh aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 6, wherein: The content of the organic solvent having the contact angle θ1 is less than 50 wt % relative to the total weight of all organic solvents contained in the functional ink.

[0020] Aspect 8 of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 7, wherein: The boiling point of the solvent with the lowest boiling point among all the organic solvents contained in the functional ink is 200° C. or higher.

[0021] A ninth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of the first to eighth aspects, wherein: The difference between the boiling point of the organic solvent having the contact angle θ1 and the boiling point of the organic solvent with the lowest boiling point among all the organic solvents contained in the functional ink is 20° C. or more.

[0022] A tenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 9, wherein: The functional material comprises at least one hole-transporting compound and at least one electron-accepting compound.

[0023] Aspect 11 of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 10, wherein: The time for drying the organic solvent contained in the functional ink under reduced pressure is 1 minute or longer and less than 15 minutes.

[0024] A twelfth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 11, wherein: The lyophobic resist contains a resin containing fluorine atoms.

[0025] A thirteenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 12, wherein: The liquid-repellent resist film is treated with the external energy for a time period of 30 seconds to 300 seconds.

[0026] A fourteenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 13, wherein: The contact angle θ1 is greater than or equal to 10° and less than 50°.

[0027] A fifteenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 14, wherein: When the contact angle between the functional ink and the surface of the liquid-repellent resist film is defined as θ4, the difference between the contact angle θ4 and the contact angle θ1 is 40° or more.

[0028] A sixteenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 15, wherein: The organic solvent contained in the functional ink includes two or more selected from the group consisting of benzoate-based solvents, naphthalene derivatives, diphenylmethane derivatives, aromatic ether-based solvents, benzene derivatives, aromatic ether-based solvents, and biphenyl derivatives.

[0029] A seventeenth aspect of the present invention is a production method, which is the method for producing an organic electroluminescent element according to any one of aspects 1 to 16, wherein: The lyophobic resist contains a colorant.

[0030] An eighteenth embodiment of the present invention is an organic electroluminescent element produced using the production method of any one of the first to seventeenth embodiments.

[0031] A nineteenth aspect of the present invention is an organic electroluminescent element comprising a functional film on openings of microscopic regions defined by banks formed by curing a lyophobic resist, wherein: When the contact angle between one solvent selected from the group consisting of Barrel Process oil B-03, 2-ethylhexyl benzoate, and benzyl benzoate and the surface of the upper surface of the bank after being peeled off by external energy is set to θ3, and the taper angle of the bank is set to θ2, at least one of the solvents satisfies the following relationship: -8°<θ2-θ3<45°. Effects of the Invention

[0032] According to the production method of the present invention, the uniformity of the thickness of the functional film in the region surrounded by the bank can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1Schematic cross-sectional view of a functional film provided on a substrate for explaining the definition of flatness U. Figure 2 This is a schematic diagram of the bank photographed using an SEM for explaining the taper angle θ2, the height of the bank, and the like. Figure 3 It is a schematic cross-sectional view showing a structural example of the organic electroluminescent element of the present invention. Figure 4 This is a graph showing the film thickness distribution of the functional film obtained in Example 1. Figure 5 This is a graph showing the film thickness distribution of the functional film obtained in Example 2. Figure 6 This is a graph showing the film thickness distribution of the functional film obtained in Example 3. Figure 7 This is a graph showing the film thickness distribution of the functional film obtained in Example 4. Figure 8 This is a graph showing the film thickness distribution of the functional film obtained in Example 5. Figure 9 This is a graph showing the film thickness distribution of the functional film obtained in Example 6. Figure 10 This is a graph showing the film thickness distribution of the functional film obtained in Comparative Example 1. Figure 11 This is a graph showing the film thickness distribution of the functional film obtained in Comparative Example 2. Figure 12 This is a graph showing the film thickness distribution of the functional film obtained in Comparative Example 3. Figure 13 This is a graph plotting flatness U against θ2-θ1. Figure 14 This is a graph showing the device characteristics of an organic electroluminescent device. [Description of Reference Numerals] 1 substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5. Luminescent layer 6 Hole blocking layer 7 Electron Transport Layer 8 Electron injection layer 9 cathode 10 Organic electroluminescent elements 101 Dike 102 substrate 103 functional membrane 104 Center of gravity of the opening DETAILED DESCRIPTION

[0034] Hereinafter, a mode for implementing the present invention will be described with reference to the accompanying drawings, etc. The embodiment described below is for illustrating one embodiment of the present invention and is not intended to limit the interpretation of the present invention. In addition, all the configurations described in each embodiment are not limited to the configurations necessary to solve the problems of the present invention.

[0035] In this specification, when the composition of the present invention is used as an ink ejected from a nozzle of an inkjet printer or the like, it may be referred to as a functional ink or simply as ink. When the composition of the present invention is used as an ink ejected from a nozzle of an inkjet printer or the like, and is ejected from the nozzle and applied to an area surrounded by banks, the ink within the area surrounded by banks may be referred to as a liquid or a liquid film, and the ink ejected from the nozzle may be referred to as a droplet.

[0036] Sometimes, a liquid or liquid film is formed by drying the liquid within the area enclosed by the dike, causing the solvent to evaporate and the solvent composition ratio of the liquid film to change. A film containing a functional material obtained by coating the composition of the present invention, volatilizing the organic solvent, and drying is called a functional film or functional layer. Furthermore, a film containing an organic compound and not containing a solvent, or a film substantially dried by volatilizing the solvent, is called an organic film. A functional film is a type of organic film.

[0037] In this specification, a bank refers to a structure formed by patterning a film made of a photosensitive composition using a conventional photolithography method to form a film having microscopic regions (also referred to as pixels). The microscopic regions of this structure are surrounded by the walls of a bank having a certain height, and the entire area of ​​this wall is referred to as the bank side. In addition, the photosensitive composition produced for the above purpose is sometimes simply referred to as a resist.

[0038] In most cases of wet-process organic EL displays, the banks are lyophobic, preventing the applied functional ink from overflowing. The resist used to produce these lyophobic banks is sometimes referred to as a lyophobic resist. Furthermore, films produced using this lyophobic resist, particularly those produced by exposure or development without the use of a patterning mask, are referred to as lyophobic resist films.

[0039] In the present specification, a heteroaryl group and an aromatic heterocyclic group have the same meanings, and an aromatic hydrocarbon structure and an aromatic hydrocarbon ring structure have the same meanings.

[0040] [Method for producing an organic electroluminescent element] The present invention relates to a method for manufacturing an organic electroluminescent element, comprising the following steps: applying a lyophobic resist onto a substrate having a conductive electrode pattern and forming a plurality of micro-region openings by photolithography; applying a functional ink comprising at least one functional material and at least one organic solvent to the openings by printing; and volatilizing the organic solvent contained in the functional ink by drying under reduced pressure. The method further relates to a method for manufacturing an organic electroluminescent element, wherein the surface of the lyophobic resist film obtained by curing the lyophobic resist is stripped by external energy to obtain a film for contact angle measurement. When the contact angle between the solvent with the highest boiling point among all organic solvents contained in the functional ink and the film for contact angle measurement is θ1, and the taper angle of the banks formed by the lyophobic resist so as to surround the openings is θ2, the following relationship is satisfied. Furthermore, the present invention relates to an organic electroluminescent element manufactured using the above-described manufacturing method. -8°<θ2-θ1<45° In this specification, the contact angle between the solvent with the highest boiling point among all organic solvents contained in the functional ink and the surface of the lyophobic resist film obtained by curing the lyophobic resist, after being peeled off by external energy, is sometimes referred to as "contact angle θ1." Similarly, the taper angle of the bank is sometimes referred to as "taper angle θ2."

[0041] <Relationship between Contact Angle θ1 and Taper Angle θ2> The present inventors focused on the relationship between the contact angle θ1 and the taper angle θ2 in order to suppress self-pinning on the side surfaces of the bank.

[0042] In practice, since it is difficult to directly measure the contact angle of the solvent on the bank side surface, a method of measuring the contact angle of the solvent by forming a simulated bank side surface has been used. The bank side surfaces are formed by etching a lyophobic resist film, which reduces the amount of lyophobic components on the bank side surfaces. Therefore, external energy is used to strip the surface of the lyophobic resist film, removing the lyophobic components on the outermost surface of the lyophobic resist film and recreating a simulated bank side surface. Furthermore, the contact angle θ1 between the solvent with the highest boiling point among all organic solvents contained in the functional ink and the simulated bank side surfaces is evaluated.

[0043] The taper angle θ2 is the angle between the side surface of the tapered bank formed by etching the lyophobic resist film and the substrate. The taper angle θ2 can be determined, for example, by measuring an SEM image of a device cross section or calculating from film thickness measurements using an optical interferometer.

[0044] As a result, it was found that film uniformity can be improved by using a combination of a functional ink and a bank in which the contact angle θ1 and the taper angle θ2 satisfy the following relationship. -8°<θ2-θ1<45°

[0045] Depending on the shape of the bank, a plurality of taper angles θ2 may exist in one pixel. In this case, the relationship between contact angle θ1 and taper angle θ2 preferably satisfies the taper angle with the largest ratio relative to the entire bank wall surface in the pixel.

[0046] <Relationship between contact angle θ1 and contact angle θ4> When the functional ink is applied to a micro area, the ink tends to be applied to the target micro area without overflowing into adjacent micro areas, that is, from the perspective of the coating properties of the functional ink, when the contact angle between the functional ink and the surface of the liquid-repellent resist film is set to θ4, the difference between the contact angle θ4 and the contact angle θ1 is preferably greater than 40°. In this specification, the contact angle between the functional ink and the surface of the liquid-repellent resist film may be referred to as “contact angle θ4”.

[0047] <Relationship between Contact Angle θ1 and Contact Angle θ5> From the viewpoint of coating properties of the functional ink, when the contact angle θ5 between the total solvent contained in the functional ink and the surface of the liquid-repellent resist film is defined as θ5, the difference between the contact angle θ5 and the contact angle θ1 is preferably 40° or greater. In this specification, the contact angle between the entire solvent contained in the functional ink and the surface of the liquid-repellent resist film may be referred to as "contact angle θ5".

[0048] (Flatness U) Flatness U, an index representing film uniformity, is defined by the following formula (X). U(%)=LF / LB×100(X)

[0049] LB and LF in formula (X) are based on Figure 1 To explain. LB represents the length of the opening (unit: μm). Specifically, LB represents the length of a straight line connecting the ends of the opening, i.e., the portion where the bank 101 meets the substrate 102, and passing through the center of gravity 104 of the opening. If there are multiple LBs, the length of the shortest of these straight lines is used as LB. For example, if the opening is rectangular, LB is the same as the length of the short side of the rectangle.

[0050] LF represents the length (unit: μm) of the portion whose thickness is no more than 15 nm greater than the average film thickness in the 50% LB described later. An example of a method for determining LF is described in detail below. It should be noted that the following method is only an example of a method for determining LF, and any method is not limited as long as it can determine LF with the same purpose. (i) A distribution of the film thickness of the functional film 103 is prepared along the straight line used in the definition of LB. The distribution can be prepared using a probe contact type step profiler or the like. (ii) Based on the above distribution, find the length of the straight line used in the definition of LB that is half of LB ( Figure 1 50% LB in the opening) and the average film thickness within the range of a straight line centered on the center of gravity 104 of the opening. (iii) Next, the length of the straight line within which the thickness of the functional film 103 within the straight line used in the definition of LB does not exceed 15 nm compared to the average film thickness determined in (ii) is determined as LF.

[0051] (mechanism) The reason why using a combination of a functional ink and a bank that satisfies the aforementioned relationship between contact angle θ1 and taper angle θ2 improves film uniformity is not entirely clear. Based on the following mechanism, the present inventors speculate that solvent volatilization in functional inks with functional films that are neither convex nor concave may be achieved within the aforementioned range of contact angle θ1 and taper angle θ2.

[0052] The drying method of the functional ink in the bank varies depending on the taper angle θ2. As the taper angle θ2 increases, the ink dries more easily near the wall surface, causing self-pinning, and the shape tends to become convex due to the coffee ring phenomenon. When a solvent with a large contact angle θ1 is used with banks having a large taper angle θ2, the solvent remaining in the ink on the bank sides evaporates slowly during the final drying stage, reducing the risk of self-pinning. Consequently, the coffee ring phenomenon (coffee stain phenomenon) is avoided, and the functional film is less likely to develop a convex shape. Conversely, for banks with a small taper angle θ2, the solvent remaining in the ink on the bank sides evaporates rapidly during the final drying stage, regardless of whether the solvent has a large or small contact angle θ1. This reduces the risk of self-pinning and prevents the coffee ring phenomenon. However, since the area adjacent to the bank dries more easily, the functional film tends to have a concave shape. Excessively large contact angles tend to increase the size of the meniscus, so a smaller contact angle θ1 is more advantageous.

[0053] <Lyophobic Resist> The lyophobic resist in the present invention can be either positive or negative, but is preferably negative from the perspective of lyophobicity. Among negative lyophobic resists, a photosensitive composition containing (A) a photopolymerization initiator, (B) an alkali-soluble resin, (C) a photopolymerizable compound, and (D) a lyophobic agent is preferred.

[0054] (A) Photopolymerization initiator The photopolymerization initiator (A) is included to absorb ultraviolet light and promote the polymerization reaction of the photopolymerizable compound (C). The photopolymerization initiator used in this application is not particularly limited, but an oxime ester-based photopolymerization initiator is preferred because it moderately absorbs ultraviolet light (i-rays) with a wavelength of 350 to 400 nm from the light source of the exposure machine to promote the polymerization reaction and improve liquid repellency. For example, photopolymerization initiators described in 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, and International Publication No. 2012 / 68879 can be used.

[0055] The content of the photopolymerization initiator is not particularly limited, but is generally 0.1% by weight or more, preferably 1% by weight or more, more preferably 2% by weight or more, and even more preferably 3% by weight or more, based on the total solids content of the lyophobic resist. It is generally 15% by weight or less, preferably 10% by weight or less, more preferably 8% by weight or less, and even more preferably 5% by weight or less. When the content is above the lower limit, sufficient lyophobicity tends to be achieved, while when the content is below the upper limit, developability tends to be improved.

[0056] (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 carboxyl groups or hydroxyl groups, but resins having carboxyl groups are preferred from the perspective of excellent developability. In addition, alkali-soluble resins having ethylenically unsaturated groups are preferred because they improve the verticality of the side surfaces of the dam and suppress the outflow of the lyophobic agent caused by thermal melting of the dam, making it easier to maintain lyophobicity.

[0057] The specific structure of the alkali-soluble resin (B) is not particularly limited, but is preferably an epoxy (meth)acrylate resin (B1) and / or an acrylic copolymer resin (B2). Here, the epoxy (meth)acrylate resin (B1) is a resin obtained 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 its anhydride. Furthermore, the epoxy (meth)acrylate resin (B1) also includes a resin obtained by reacting a compound having further reactive functional groups with the carboxyl groups of the resin obtained in the above reaction. For example, the alkali-soluble resins described in International Publication Nos. 2004 / 81621, 2008 / 129986, 2008 / 153000, 2018 / 43746, 2018 / 101314, and 2021 / 90836 can be used.

[0058] The content of the alkali-soluble resin (B) in the lyophobic resist of the present invention is not particularly limited, but is generally 5% by weight or more, preferably 10% by weight or more, more preferably 20% by weight or more, further preferably 30% by weight or more, even more preferably 40% by weight or more, particularly preferably 50% by weight or more, and generally 90% by weight or less, preferably 80% by weight or less, and more preferably 70% by weight or less, relative to the total solid content. When the content is above the lower limit, the shape of the partition walls tends to be improved, and when the content is below the upper limit, the lyophobicity tends to be improved.

[0059] (C) Photopolymerizable compound (C) The photopolymerizable compound is believed to improve the curability of the resist film and enhance its liquid repellency. The photopolymerizable compound used herein is not particularly limited to the following, but refers to a compound having one or more ethylenically unsaturated bonds in the molecule. From the perspectives of polymerizability, crosslinking properties, and the ability to increase the difference in developer solubility between the exposed and non-exposed areas, a compound having two or more ethylenically unsaturated bonds in the molecule is preferred. Compounds in which the unsaturated bonds are derived from a (meth)acryloyloxy group, i.e., (meth)acrylate compounds, are more preferred.

[0060] Examples of photopolymerizable compounds include esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids; esters of aromatic polyhydroxy compounds and unsaturated carboxylic acids; and esters obtained by esterification of polyhydroxy compounds such as aliphatic polyhydroxy compounds and aromatic polyhydroxy compounds with unsaturated carboxylic acids and polycarboxylic acids. From the perspective of lyophobicity, esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids are preferred. For example, more preferred are dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, 2-tri(meth)acryloyloxymethylethyl phthalate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate.

[0061] The content of the photopolymerizable compound (C) in the lyophobic resist of the present invention is not particularly limited, but is generally 1% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more, based on the total solids, and is generally 80% by weight or less, preferably 60% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less. When the content is above the lower limit, the perpendicularity of the side surfaces of the partition walls during exposure tends to be improved, while when the content is below the upper limit, the developability tends to be improved.

[0062] (D) Lyophobic agent (D) The lyophobic agent preferably contains a fluorine-containing resin, more preferably a fluorine-containing resin having a crosslinking group. By using such a lyophobic agent, the lyophobic resist contains a fluorine-containing resin or a fluorine-containing resin having a crosslinking group, preferably a fluorine-containing resin. As a result, the surface of the bank can be rendered lyophobic. This prevents mixing of inks between adjacent microscopic areas when applying the functional ink.

[0063] Examples of crosslinking groups include epoxy groups and ethylenically unsaturated groups. Ethylenically unsaturated groups are preferred from the perspective of suppressing the outflow of the lyophobic component of the developer. By using a lyophobic agent having a crosslinking group, the crosslinking reaction on the surface of the formed resist film can be accelerated during exposure, and the lyophobic agent is less likely to outflow during the development process. As a result, the resulting partition wall can also exhibit high lyophobicity. Furthermore, by using a fluorine-containing resin, the fluorine-containing resin is oriented along the surface of the partition wall, tending to prevent the leakage or mixing of the functional ink.

[0064] The fluorine atom may be contained in the form of, for example, a fluoroalkyl group, a fluoroalkenyl group, a fluoroalkylene group, etc. Of these, from the viewpoint of liquid repellency and prevention of bleeding or mixing of the functional ink, a fluoroalkyl group and a fluoroalkylene group are preferred, and a fluoroalkyl group is more preferred.

[0065] The liquid repellent is preferably an acrylic copolymer, which tends to prevent bleeding or mixing of the functional ink.

[0066] The content of the (D) lyophobic agent is not particularly limited, but is generally 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and generally 5% by weight or less, preferably 3% by weight or less, and more preferably 2% by weight or less, relative to the total solids. A content of at least the lower limit tends to exhibit high lyophobicity, while a content of at most the upper limit tends to suppress outflow to small areas.

[0067] (E) Colorant The lyophobic resist usable in the present invention may contain (E) a colorant. By containing the (E) colorant, appropriate light absorption properties can be obtained, and in particular, appropriate light shielding properties can be obtained when used to form a light shielding member such as a partition wall.

[0068] The type of the colorant (E) that can be used in the lyophobic resist of the present invention is not particularly limited, and either a pigment or a dye may be used. From the viewpoint of durability and heat resistance, a pigment is preferably used.

[0069] The type of pigment that can be used as the colorant (E) is not particularly limited, but organic pigments are preferred from the viewpoint of high dielectric constant and low dielectric constant. Examples of organic pigments include organic color pigments and organic black pigments. Organic color pigments are organic pigments that exhibit colors other than black, and examples include red pigments, orange pigments, blue pigments, violet pigments, green pigments, and yellow pigments. Examples of organic black pigments include perylene-based black pigments, aniline-based black pigments, and benzodifuranone-based black pigments. From the viewpoint of suppressing ultraviolet absorption, achieving high curability, and facilitating control of the shape of the cured product, it is preferable to use an organic coloring pigment, and from the viewpoint of light-shielding properties, it is preferable to use an organic black pigment. (E) The colorant may be used alone or in combination of two or more.

[0070] The content of the colorant (E) in the lyophobic resist of the present invention is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more, relative to the total solid content, and is generally 40% by weight or less, preferably 30% by weight or less, and more preferably 25% by weight or less. When the content is at least the lower limit, the light-shielding properties of the partition walls tend to be improved, while when the content is at most the upper limit, the lyophobic properties tend to be improved.

[0071] (Other additives) In addition to the aforementioned ethylenically unsaturated compound of component (A), the photopolymerization initiator of component (B), the alkali-soluble binder of component (C), and the liquid repellent of component (D), surfactants, ultraviolet absorbers, polymerization inhibitors, antioxidants, development modifiers, silane coupling agents, epoxy compounds, other resins, etc. can also be appropriately formulated.

[0072] The lyophobic resist can be used in a state where each component is appropriately dissolved or dispersed in a solvent. The solvent is not particularly limited, and examples thereof include the organic solvents described below. Glycol monoalkyl ethers, such as propylene glycol monomethyl ether and 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, and 3-methoxybutyl acetate; Glycol diacetates, such as 1,3-butanediol diacetate, 1,4-butanediol diacetate, 1,6-hexanol diacetate, etc.; Alkoxycarboxylic acids, such as ethyl acetate, propyl acetate, butyl acetate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, etc. Among these, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and 3-methoxy-1-butyl acetate are preferred.

[0073] <Film Formation of Liquid-Repellent Resist Film> Typically, when forming a lyophobic resist film, the (D) lyophobic agent is distributed on the outermost surface of the film, with the lyophobic component being almost absent from the bulk of the film. Consequently, when patterning tiny openings using methods such as photolithography, the lyophobic component is absent from the bank side surfaces. On the other hand, since the bank side surfaces, which exhibit properties different from those of typical lyophobic bank surfaces, are extremely small, evaluating various physical properties such as contact angle on the bank side surfaces is difficult.

[0074] In the present invention, to evaluate the contact angle on the side surfaces of the banks, where the lyophobic component is hardly distributed, the lyophobic component on the outermost surface of the lyophobic resist film is stripped off to reproduce the state of the side surfaces of the banks on the outermost surface of the resist film. The contact angle is then measured on this surface, thereby simulating the physical property evaluation on the difficult-to-measure side surfaces of the banks. In this specification, such a film used for contact angle measurement is sometimes referred to as a "simulated bank side surface film."

[0075] <Measurement of cone angle> The taper angle in the pattern portion of the patterned lyophobic resist film, that is, the taper angle θ2, is measured and calculated using a scanning electron microscope (SEM). Figure 2 As shown, the taper angle is the angle of the acute angle formed by the intersection of a line representing the bank's lower surface and a line linearly fitted to the slope between the lines representing the bank's upper surface and lower surface in an SEM image. In this specification, the taper angle thus obtained is referred to as θ2.

[0076] As one embodiment of the present invention, it is preferred that the taper angle θ2 is larger than 30° and the bank height is 1.9 μm or less. The length of the bank slope is uniquely determined by the following formula (Y). Length of dike slope (μm) = dike height (μm) / tanθ2(Y)

[0077] Table 1 shows the values ​​of the length (μm) of the bank slope corresponding to the combinations of the bank height (μm) and the taper angle θ2 (°) calculated from the above formula (Y). As pixel width decreases with higher definition, the bank slope length is preferably 3 μm or less. To keep the bank slope length below 3 μm, the bank height is allowed to be up to 1.7 μm, so the taper angle θ2 is preferably 30° or greater. Similarly, to keep the bank slope length below 3 μm, the taper angle θ2 is allowed to be up to 40°, so the bank height is preferably 1.9 μm or less.

[0078] [Table 1] Table 1

[0079] In one embodiment of the present invention, the taper angle θ2 is preferably less than 70°. If θ2 is greater than 70°, flatness is severely degraded, and disconnection may occur during device fabrication. Therefore, θ2 is more preferably less than 60°.

[0080] In one embodiment of the present invention, the taper angle θ2 is preferably greater than 30° and less than 70°, and the bank height is preferably 1.9 μm or less. The bank height within the θ2 range is more preferably 1.7 μm or less, and even more preferably 1.5 μm or less.

[0081] <Surface Peeling of Lyophobic Resist Film> Regarding the film formation of the liquid-repellent resist film, a spin coating method, a die coating method, a rod coating method, a spray coating method, an inkjet method, etc. can be used. Preferably, a spin coating method, a die coating method, an inkjet method can be used, and more preferably, a spin coating method or a die coating method can be used. In addition, the surface of the liquid-repellent resist film is preferably stripped using external energy. As a method of imparting external energy, UV / ozone treatment such as UV / ozone cleaning method or plasma treatment such as plasma etching method, excimer UV treatment such as excimer UV method, etc. can be mentioned. Preferably, the surface of the liquid-repellent resist film based on external energy is stripped by UV / ozone treatment or plasma treatment, and more preferably by plasma etching method. The outermost surface of the lyophobic resist film is preferably peeled off by external energy. In this specification, the "surface" of the lyophobic resist film refers to an area including both areas on the film surface where the lyophobic agent is distributed and areas where the lyophobic agent is not distributed, and the "outermost surface" refers to an area where only the lyophobic agent is distributed.

[0082] In the present invention, there is a difference in lyophobicity between the lyophobic resist film surface and the lyophobic resist film surface after the region where the lyophobic agent is distributed is peeled off by external energy treatment. Therefore, the difference between the contact angle θ1 and the contact angles θ4 and θ5 described later tends to increase.

[0083] In order to remove the lyophobic agent from the surface and approach the side surface, the time for treating the lyophobic resist film with external energy is preferably 30 seconds or longer, more preferably 45 seconds or longer, and most preferably 60 seconds or longer. On the other hand, if the surface treatment is performed for a long time, the surface roughness increases, resulting in a state different from that of the bank side surface. Therefore, the time for treating the lyophobic resist film with external energy is preferably 300 seconds or shorter, more preferably 250 seconds or shorter, and most preferably 200 seconds or shorter. When the time for treating the liquid-repellent resist film with external energy is set to 30 seconds or more and 300 seconds or less, the result of the contact angle measurement becomes very stable, which is preferable.

[0084] As one method of treating the lyophobic resist film with external energy, there is a method in which the upper surface of the bank formed by curing the lyophobic resist is peeled off by the external energy.

[0085] As one embodiment of the present invention, when the contact angle between a solvent selected from Barrel Process Oil B-03 (manufactured by Matsumura Oil Co., Ltd.), 2-ethylhexyl benzoate, and benzyl benzoate and the surface of the upper surface of the bank after being peeled off by external energy is set to θ3, and the taper angle of the bank is set to θ2, at least one of the solvents preferably satisfies the following relationship: -8°<θ2-θ3<45°. In this specification, the contact angle between a solvent selected from Barrel Process Oil B-03, 2-ethylhexyl benzoate, and benzyl benzoate and the upper surface of the bank after being peeled by external energy may be referred to as "contact angle θ3".

[0086] As one embodiment of the present invention, the difference between θ2 and θ3 is less than 45°. In order to improve uniformity, it is preferably less than 40°, more preferably less than 35°, greater than -8°, preferably greater than 0°, more preferably greater than 5°, and further preferably greater than 10°.

[0087] As one embodiment of the present invention, the contact angle θ3 is preferably greater than 0° and less than 78°, more preferably greater than 10° and less than 50°, and even more preferably greater than 10° and less than 30°. A contact angle θ3 of less than 78° is preferred because a difference in drying rate distribution is less likely to occur between the side surfaces of the bank and the center of the opening, which prevents significant convection and improves flatness.

[0088] Furthermore, one embodiment of the present invention may be an organic electroluminescent element having a functional film on openings of microscopic regions defined by banks formed by curing a lyophobic resist, wherein, when the contact angle between a solvent selected from BarrelProcess Oil B-03, 2-ethylhexyl benzoate, and benzyl benzoate and the surface of the upper portion of the bank after exfoliation by external energy is set to θ3, and the taper angle of the bank is set to θ2, at least one of the solvents satisfies the following relationship: -8°<θ2-θ3<45°.

[0089] The preferred range of the difference between θ2 and θ3 in the organic electroluminescent element is as described above.

[0090] <Contact Angle> The contact angle in the present invention refers to the angle between the tangent line of the outermost surface of the droplet and the substrate surface at the point where the outermost surface of the droplet contacts the substrate when an image of a droplet dropped on a substrate is observed from the front side. Unless otherwise specified, the contact angle value is a value measured in an environment set at 23° C. and is the average value of the contact angle measured three times 0.1 seconds after the dropwise addition.

[0091] [Functional ink] According to the present invention, the functional ink used in the present invention comprises at least one functional material and at least one organic solvent. The functional ink preferably comprises at least two organic solvents. The inclusion of at least two organic solvents suppresses self-pinning and reduces the meniscus, thereby tending to improve film thickness uniformity. Furthermore, the solubility of the functional material and the drying speed of the ink can be controlled, and during the reduced-pressure drying step to volatilize the organic solvent, a skin layer formed by surface curing alone tends to be less likely to form.

[0092] As one embodiment of the present invention, when the contact angle between the functional ink and the surface of the liquid-repellent resist film is set to θ4, the difference between the contact angle θ4 and the contact angle θ1 is preferably 40° or more, more preferably 41° or more, further preferably 43° or more, preferably 80° or less, more preferably 70° or less, and further preferably 60° or less.

[0093] As one embodiment of the present invention, the contact angle θ4 is preferably 45° or greater, more preferably 50° or greater, and even more preferably 60° or greater. A contact angle θ4 of 45° or greater is preferred because it tends to reduce the tendency of the applied ink to overflow into adjacent microscopic areas.

[0094] As one embodiment of the present invention, when the contact angle between the total solvent contained in the functional ink and the surface of the liquid-repellent resist film is set to θ5, the difference between the contact angle θ5 and the contact angle θ1 is preferably 40° or more, more preferably 41° or more, further preferably 43° or more, preferably 80° or less, more preferably 70° or less, and further preferably 60° or less.

[0095] As one embodiment of the present invention, the contact angle θ5 is preferably 45° or greater, more preferably 50° or greater, and even more preferably 60° or greater. A contact angle θ5 of 45° or greater is preferred because the coating properties of the functional ink are improved.

[0096] <Organic Solvents> The organic solvents that can be used in the present invention will be described below with reference to examples.

[0097] (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, it is preferably an aromatic organic solvent, a chain aliphatic organic solvent, or a cyclic aliphatic organic solvent, more preferably an aromatic organic solvent or a cyclic aliphatic organic solvent, and even more preferably an aromatic organic solvent.

[0098] The aromatic organic solvent that can be used in the present invention is not particularly limited, but preferred examples include water-insoluble aromatic solvents such as aromatic hydrocarbon solvents, aromatic ester solvents, aromatic ether solvents, and aromatic ketone solvents.

[0099] In addition, as one embodiment of the present invention, on the surface of the aforementioned film for contact angle measurement, when the contact angle between the film and the solvent with the highest boiling point among all the organic solvents contained in the functional ink is set to θ1, and the cone angle of the aforementioned partition is set to θ2, the difference between θ2 and θ1 is less than 45°. In order to improve uniformity, it is preferably less than 40°, more preferably less than 35°, greater than -8°, preferably greater than 0°, more preferably greater than 5°, and further preferably greater than 10°.

[0100] As one embodiment of the present invention, since the preferred range of θ2 is greater than 30° and less than 70°, θ1 is preferably greater than 0° and less than 78°, more preferably greater than 10° and less than 50°, and even more preferably greater than 10° and less than 30°. When θ1 is less than 78°, a difference in drying rate distribution between the bank and the center of the pixel is less likely to occur, which prevents significant convection and improves flatness, making this a preferred setting.

[0101] As the aromatic hydrocarbon solvent, benzene derivatives, naphthalene derivatives, hydronaphthalene derivatives, biphenyl derivatives, and diphenylmethane derivatives are preferable.

[0102] The benzene derivatives are not particularly limited, but are preferably benzene derivatives in which the total number of carbon atoms of the substituents is 2 or more and 12 or less, and in which the substituents have a linear, branched, or cyclic alkyl group, and examples thereof include n-ethylbenzene, 1,3,5-trimethylbenzene, n-propylbenzene, isopropylbenzene, 1,3-diisopropylbenzene, 1,3,5-triisopropylbenzene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, n-pentylbenzene, n-hexylbenzene, n-heptylbenzene, n-octylbenzene, n-nonylbenzene, n-decylbenzene, dodecylbenzene, and cyclohexylbenzene.

[0103] The naphthalene derivatives are not particularly limited, but preferably have a total carbon number of 2 to 6 substituents and are substituted with a linear, branched, or cyclic alkyl group. Examples thereof include 1-methylnaphthalene, 2-methylnaphthalene, 1-ethylnaphthalene, 2-ethylnaphthalene, 2-isopropylnaphthalene, 2,6-dimethylnaphthalene, 2,7-diisopropylnaphthalene, 1-butylnaphthalene, 2-cyclohexylnaphthalene, and 1-phenylnaphthalene. Alternatively, 1-naphthylaldehyde may be used.

[0104] The hydronaphthalene derivative is not particularly limited, and examples thereof include tetralin, 1,2-dihydronaphthalene, and 1,4-dihydronaphthalene. These may be substituted with an alkyl group having 1 to 6 carbon atoms.

[0105] The biphenyl derivative is not particularly limited, but is preferably a biphenyl derivative substituted with an alkyl group having 1 to 6 carbon atoms, and examples thereof include 3-ethylbiphenyl, 4-isopropylbiphenyl, and 4-butylbiphenyl.

[0106] The diphenylmethane derivative is not particularly limited, but is preferably a diphenylmethane derivative substituted with an alkyl group having 1 to 6 carbon atoms, and examples thereof include 1,1-diphenylethane, 1,1-diphenylpentane, 1,1-diphenylhexane, 1,1-bis(3,4-dimethylphenyl)ethane, and benzyltoluene.

[0107] Examples of the aromatic ester solvent include benzoate solvents, phenyl acetate solvents, and phthalate solvents.

[0108] Benzoate solvents are compounds containing benzoic acid and an ester bond. Compounds in which benzoic acid, which may have a substituent, forms an ester bond with an alcohol having 1 to 12 carbon atoms can be used. The substituents that may be present are not particularly limited, but are preferably linear, branched, or cyclic alkyl groups having 1 to 12 carbon atoms, linear, branched, or cyclic alkoxy groups having 1 to 12 carbon atoms, or aromatic substituents having 6 to 12 carbon atoms. Multiple substituents may be present; if multiple substituents are present, the total number of carbon atoms in the substituents is preferably 2 to 12. Examples of the benzoate-based solvent include ethyl benzoate, n-butyl benzoate, n-amyl benzoate, isoamyl benzoate, n-hexyl benzoate, 2-ethylhexyl benzoate, benzyl benzoate, methyl 4-methylbenzoate, methyl 3-methylbenzoate, methyl 2-methylbenzoate, ethyl 4-methylbenzoate, ethyl 3-methylbenzoate, ethyl 2-methylbenzoate, and ethyl 4-methoxybenzoate.

[0109] The phenyl acetate-based solvent is not particularly limited, and examples thereof include ethyl phenylacetate.

[0110] The phthalate-based solvent is not particularly limited, but examples thereof include dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

[0111] Other preferred aromatic ester solvents include 2-phenoxyethyl acetate and 2-phenoxyethyl isobutyrate.

[0112] The aromatic ether solvent is a compound having an aromatic ring and an ether bond, and is not particularly limited, but the following compounds may be mentioned. Benzene derivatives having a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms and an ether bond, for example, anisole, 4-methylanisole, butylphenyl ether, hexylphenyl ether, diphenyl ether, benzylphenyl ether, and dibenzyl ether; A diphenyl ether derivative substituted with a linear or branched alkyl group having 1 to 6 carbon atoms, for example, 2-phenoxytoluene, 3-phenoxytoluene, and 4-phenoxytoluene; Benzene derivatives having two linear or branched alkyl groups having 1 to 6 carbon atoms and an ether bond, for example, 1,4-diethoxybenzene and 1-ethoxy-4-hexyloxybenzene; Other aromatic ether solvents include 2-phenoxyethanol and phenoxyethoxyethanol.

[0113] 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.

[0114] The organic solvent contained in the functional ink preferably includes two or more selected from the group consisting of benzoate-based solvents, naphthalene derivatives, diphenylmethane derivatives, aromatic ether-based solvents, benzene derivatives, aromatic ether-based solvents, and biphenyl derivatives.

[0115] It should be noted that the organic solvent may contain a surface modifier to control surface tension. By adding a small amount of a surface modifier to a liquid, functionality can be imparted to the liquid surface after application of the liquid, or to the resulting solid surface. Examples of the functions imparted include lyophobicity, non-adhesiveness, wettability, smoothness, dispersibility, and defoaming properties.

[0116] As a material that can be used as a surface modifier, a material that easily segregates on the liquid surface is preferable, and specific examples thereof include materials containing silicon or fluorine (polymers, oligomers, low molecular weight substances), paraffin wax, and surfactants. Surfactants are substances with an amphiphilic chemical structure comprising a hydrophilic portion (group) and a hydrophobic portion (group). They are used in a wide range of applications, including dispersants, foaming agents, defoaming agents, emulsifiers, food additives, moisturizers, antistatic agents, wettability enhancers, lubricants, and rust inhibitors. Such surfactants are broadly classified into surfactants having cationic, anionic, or amphoteric hydrophilic portions and surfactants having nonionic hydrophilic portions. In the present invention, nonionic surfactants are preferred in order not to hinder the conduction of electricity in the organic electroluminescent element.

[0117] (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 230°C or higher, even more preferably 250°C or higher, and most preferably 270°C or higher. Furthermore, it preferably has a boiling point of 350°C or lower, more preferably 340°C or lower, and even more preferably 330°C or lower. Of all the organic solvents contained in the functional ink of the present invention, the solvent with the lowest boiling point is the first solvent, and the solvent with the highest boiling point is the second solvent.

[0118] For example, because the ink filled into the inkjet head begins to dry from the nozzle tip, the solids concentration at the nozzle tip tends to increase. If this condition persists, it can cause fatal damage to the inkjet device, such as precipitation of solids at the nozzle tip, ultimately leading to nozzle clogging. To avoid problems caused by nozzle clogging, the solvent with the lowest boiling point (the first solvent) is preferably an organic solvent with a boiling point of 200°C or higher, more preferably 230°C or higher, even more preferably 250°C or higher, and most preferably 270°C or higher.

[0119] On the other hand, from the perspective of manufacturing an organic electroluminescent element, if the organic solvent is not volatilized to obtain a functional film, the element cannot be produced. Therefore, a boiling point range that allows drying using a reduced-pressure drying device is required. From this perspective, the boiling point of the second solvent is preferably 350°C or lower, more preferably 340°C or lower, and even more preferably 330°C or lower.

[0120] (Vapor Pressure) Vapor pressure refers to the pressure of the vapor phase when the liquid and vapor phases of a solvent reach laminar equilibrium. The boiling point of a solvent is the temperature at which the partial vapor pressure of the solvent equals the vapor pressure. Vapor pressure can be determined experimentally using methods such as the static method, boiling point method, isoteniscope, and gas flow method. However, the vapor pressure herein refers to the vapor pressure calculated at 25°C using Advanced Chemistry Development (ACD / Labs) software V11.02 (Copyright 1994-2021 ACD / Labs).

[0121] (Type and amount of organic solvents contained) The organic solvent used in the present invention may be a single solvent, or more preferably a mixed solvent of two or more.

[0122] When using a mixed solvent of two or more, as described above, in order to strike a balance between suppressing drying at the nozzle tip of the inkjet head and facilitating drying during film formation, two organic solvents with different boiling points may be used. In order to prevent the nozzle from drying at the nozzle tip of the inkjet head and clogging the nozzle, it is preferred that an organic solvent with a boiling point of 270°C or higher be included. In addition, the organic solvent with a boiling point of 270°C or higher may be one or more. In order to prevent the ink from drying at the nozzle tip and clogging the nozzle, the organic solvent with a boiling point of 270°C or higher is preferably included in an amount of 10% by weight or more, more preferably 15% by weight or more, and even more preferably 25% by weight or more, relative to the entire composition.

[0123] On the other hand, to prevent drying at the nozzle tip with a high-boiling-point solvent and ensure ink drying properties, the residual solvent may contain an organic solvent with a low boiling point. The low-boiling-point organic solvent preferably has a boiling point of 265°C or lower, more preferably 250°C or lower. The low-boiling-point organic solvent may be one or more. To improve the drying properties of the composition, the low-boiling-point organic solvent preferably comprises 30% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more of the total composition.

[0124] Furthermore, if the boiling point of the organic solvent with the highest boiling point among all the organic solvents contained in the functional ink is relatively close to the boiling points of the other organic solvents, the organic solvents may azeotropize during the drying process, potentially preventing the organic solvent with the highest boiling point from fully functioning. To prevent this, the difference between the boiling point of the organic solvent with the highest boiling point in the functional ink and the boiling point of the organic solvent with the lowest boiling point among all the organic solvents contained in the functional ink is preferably 10°C or more, more preferably 20°C or more, and even more preferably 30°C or more.

[0125] The content of the organic solvent having the aforementioned θ1 contact angle is preferably 1% by weight or greater, more preferably 2% by weight or greater, and most preferably 5% by weight or greater, relative to the total weight of all organic solvents contained in the functional ink. Furthermore, the content of the organic solvent having the aforementioned θ1 contact angle is preferably less than 50% by weight, more preferably less than 40% by weight, and even more preferably less than 30% by weight, relative to the total weight of all organic solvents contained in the functional ink. Furthermore, the content of the organic solvent having a θ1 contact angle relative to the total weight of all organic solvents contained in the functional ink is preferably 1% by weight or more and less than 95% by weight, more preferably 2% by weight or more and less than 80% by weight, even more preferably 5% by weight or more and less than 50% by weight, and most preferably 5% by weight or more and less than 30% by weight. Within this range, the function of sufficiently determining the flatness of the film is achieved, and other solvents may be appropriately included in consideration of solubility and other factors.

[0126] Furthermore, if the boiling points of the organic solvents in the mixed solvent are close to each other, these organic solvents will form an azeotrope and will not function as a high-boiling-point solvent. Therefore, the difference between the boiling point of the organic solvent having the contact angle θ1 and the boiling point of the organic solvent with the lowest boiling point among all the organic solvents contained in the functional ink is preferably 10°C or more, more preferably 20°C or more, and even more preferably 30°C or more.

[0127] In addition, in the present invention, the boiling point of the solvent is a value measured under atmospheric pressure.

[0128] (Combination of organic solvents) The combination of the high-boiling-point organic solvent and the low-boiling-point organic solvent is not particularly limited, but is preferably any one of benzene which may have a substituent, naphthalene which may have a substituent, diphenylmethane which may have a substituent, biphenyl which may have a substituent, benzoate, aromatic ether, and aromatic ketone.

[0129] Preferably, the organic solvent with a high boiling point includes one or more of octylbenzene, nonylbenzene, decylbenzene, dodecylbenzene, hexyl benzoate, 2-ethylhexyl benzoate, benzyl benzoate, acetylnaphthalene, methyl naphthyl acetate, ethyl naphthyl acetate, isopropylnaphthalene, diisopropylnaphthalene, butylnaphthalene, pentylnaphthalene, methoxynaphthalene, dimethyl phthalate, diethyl phthalate, ethylbiphenyl, isopropylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, butylbiphenyl, 1,1-diphenylethane, 1,1-diphenylpropane, 1,1-diphenylbutane, 1,1-diphenylpentane, 1,1-diphenylhexane, and 2-phenoxyethyl isobutyrate.

[0130] In addition, preferably, as the organic solvent with a low boiling point, one or more of methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, ethyl benzoate, propyl benzoate, butyl benzoate, isobutyl benzoate, pentyl benzoate, isopentyl benzoate, methyl benzoate, and ethyl benzoate can be cited.

[0131] <Viscosity> Taking into account a coating method such as filling an inkjet head and then discharging, the viscosity of the functional ink of the present invention at 23° C. is preferably 1 mPa·s or more and 20 mPa·s or less. Typically, inkjet heads utilizing piezoelectric elements use the deformation pressure of the piezoelectric element to extrude the composition filled in the ink chamber within the inkjet head. Therefore, for compositions with a viscosity greater than 20 mPa·s, the pressure of the piezoelectric element becomes insufficient, preventing ejection. On the other hand, to ensure that the composition easily retains the ink within the inkjet head and prevents dripping from the nozzle, the viscosity of the composition is preferably greater than 1 mPa·s. In the present invention, the viscosity of the organic solvent can be measured using an E-type viscometer RE85L (manufactured by Toki Sangyo Co., Ltd.) at 23° C. and a cone-plate rotation speed of 20 rpm to 100 rpm.

[0132] <Surface Tension> The surface tension of the functional ink of the present invention is preferably more than 25mN / m, preferably less than 45mN / m. It is believed that by making the surface tension of the functional ink within the range, it is possible to utilize an inkjet device to carry out stable ejection or stably film forming. In the case of a functional ink with low surface tension, significant wetting can be extended to the nozzle plate of an inkjet head, easily causing ejection instability or flight offset. In addition, in the case where the surface tension is low, the composition ejected can cut the liquid position improperly and easily extend, and is also likely to become the main cause of satellite droplets (satellite) etc. On the other hand, when the surface tension is too high, convection caused by Laplace pressure (Laplace pressure) is easily generated in the drying after being coated on the pixel portion of the substrate, and film shape easily becomes unstable.

[0133] When two or more organic solvents are mixed, the difference in surface tension between the organic solvents is preferably 20 mN / m or less, more preferably 10 mN / m or less, and even more preferably 5 mN / m or less.

[0134] The surface tension of the organic solvent or functional ink in the present invention can be measured at 23.0° C. by a plate pulling method using a platinum plate or a hanging drop method using a contact angle meter DM0-501 (manufactured by Kyowa Interface Science Co., Ltd.).

[0135] [Other ingredients] In the present invention, the functional ink may contain ingredients other than the functional material and organic solvent, such as antioxidants and additives that modify the physical properties of the functional ink. These ingredients are also important factors in determining the storage stability of the functional ink and the stability of ejection from the inkjet head. However, they significantly affect the inherent performance of the functional ink, which is undesirable. Therefore, the amount of these ingredients 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, relative to the total weight of the functional ink.

[0136] [Functional Materials] Functional materials refer to materials having functions such as charge transport and charge injection or improving these functions. As charge transport, hole transport is preferred, and as charge injection function, hole injection is preferred. A material having a function of improving charge transport refers to a material having a function of improving the charge transport properties of other materials with charge transport properties. A material having a function of improving charge injection refers to a material having a function of improving the charge injection properties of other materials with charge injection properties. For example, by doping an electron accepting material in a hole transporting material, the electron accepting material oxidizes the hole transporting material to generate cationic free radicals, thereby improving the hole transport and / or hole injection properties of the hole transporting material. In this case, the electron accepting material is a material that improves the hole transport and / or hole injection properties of the hole transporting material.

[0137] As the functional material in the present invention, the hole injection layer material or the hole transport layer material described below can be preferably used, and the hole injection layer material is particularly preferred. Details of the functional materials that can be used in the present invention will be described below with reference to specific examples, but the scope of the present invention is not limited to the functional materials described below.

[0138] <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 is preferably a high molecular compound.

[0139] About charge transporting polymer compounds, generally there is a larger charge transport performance in the main chain direction of the polymer compound, so the more the average molecular weight is increased, the more stable charge transport can be achieved. In order to ensure the function of transporting charge, the weight average molecular weight is generally more than 10,000, preferably more than 12,000, and more preferably more than 15,000. On the other hand, the polymer compound with a large weight average molecular weight has the characteristic that the viscosity becomes higher when the ink is made, and in order to make it within the preferred viscosity range as described above, it is preferred that the weight average molecular weight is reduced to a certain extent. Specifically, the weight average molecular weight of the polymer compound is generally less than 1,000,000, preferably less than 500,000, more preferably less than 100,000, further preferably less than 70,000, and particularly preferably less than 50,000.

[0140] Regarding the charge transport low molecular weight compound, the molecular weight is usually 5,000 or less, preferably 4,000 or less, more preferably 3,000 or less, further preferably 2,500 or less, and particularly preferably 2,000 or less. On the other hand, when forming a film as a common functional film, baking at a certain temperature volatilizes the residual solvent to make a functional film without impurities, so that it can fully play its role as an organic electroluminescent element. At this time, when a material with low heat resistance is used, phenomena such as film shrinkage or film shedding may occur, which may result in the inability to obtain a flat film. From the viewpoint of ensuring the heat resistance of the film, the molecular weight of the charge transport low molecular weight compound is preferably 500 or more, more preferably 650 or more, and further preferably 800 or more.

[0141] In order to improve the charge transport performance, the functional ink of the present invention preferably contains an electron-accepting compound. Furthermore, as functional materials, the functional ink of the present invention preferably contains at least one hole-transporting compound and at least one electron-accepting compound.

[0142] It should be noted that the weight average molecular weight and number average molecular weight of the charge transport polymer compound in the present invention are determined by SEC (size exclusion chromatography). In SEC measurement, the higher the molecular weight component, the shorter the dissolution time, and the lower the molecular weight component, the longer the dissolution time. By using a calibration curve calculated from the dissolution time of polystyrene (standard sample) with a known molecular weight, the dissolution time of the sample is converted into molecular weight to calculate the weight average molecular weight and number average molecular weight.

[0143] <Crosslinking Group> In the present invention, in order to prevent the charge transport low molecular compound from being dissolved into the solvent of the composition further coated on the upper layer of the functional film, it is preferred that the charge transport low molecular compound has a cross-linking group. In this case, in order to prevent only the charge transport material from being chain-crosslinked and not dissolved, the number of cross-linking groups contained in one molecule of the charge transport low molecular compound is preferably 2 or more. In addition, the same is true for the charge transport high molecular compound, and the number of cross-linking groups contained in one repeating unit is preferably 2 or more. Further, in order to more reliably suppress the dissolution of the charge transport high molecular compound, it is preferred that there are 2 or more cross-linking groups per 10,000 molecular weight.

[0144] The crosslinking group is preferably a substituent that undergoes a chemical reaction by an external force such as light or heat. A preferred example of a crosslinking group is preferably a thermally crosslinked group that undergoes a crosslinking reaction by heat, but is not limited to the following. For example, groups derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, an acrylic group, a styryl group, etc. It should be noted that any crosslinking group may also have a substituent, preferably a methyl group, a methoxy group, etc. As described above, the functional ink of the present invention preferably contains a functional material having a crosslinking group. More preferably, all the functional materials contained in the functional ink of the present invention have a crosslinking group.

[0145] [Content of organic solvent and functional material] The content of the functional material in the functional ink of the present invention is not particularly limited, but in order to achieve a desired functional film thickness on the organic electroluminescent element, it is preferably 0.1% by weight or greater, more preferably 0.5% by weight or greater, and even more preferably 1.0% by weight or greater. Furthermore, from the perspective of suppressing precipitation in the functional ink, it is preferably 20% by weight or less, more preferably 15% by weight or less, and even 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 wt % or less, more preferably 99.5 wt % or less, and even more preferably 99.0 wt % or less, and is preferably 80 wt % or more, more preferably 85 wt % or more, and even more preferably 90 wt % or more.

[0146] In the present invention, the charge-transporting low-molecular-weight compound is used to improve the thickness uniformity of the functional film within the region defined by the bank. The charge-transporting low-molecular-weight compound is preferably present in an amount of 10% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more, relative to the total functional material. On the other hand, increasing the charge-transporting low-molecular-weight compound content can lead to problems with heat resistance, as described above. Therefore, the charge-transporting low-molecular-weight compound is preferably present in an amount of 75% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less, relative to the total functional material. In the present invention, the charge-transporting polymer compound is primarily a material used for charge transport and preferably accounts for 20% by weight or more, more preferably 25% by weight or more, and even more preferably 30% by weight or more of the total functional materials. On the other hand, increasing the charge-transporting polymer compound content makes it difficult to form a flat film due to thickening during the drying process. Therefore, the charge-transporting polymer compound is preferably 90% by weight or less, more preferably 85% by weight or less, and even more preferably 80% by weight or less of the total functional materials. The content ratio of the low molecular weight compound to the high molecular weight compound is preferably low molecular weight compound:high molecular weight compound = 1:0.3 to 3, particularly 1:1 to 2, in terms of weight ratio, taking the above-mentioned factors into consideration.

[0147] When the functional ink of the present invention contains an electron-accepting compound, from the perspective of generating carriers for the charge-transporting compound and improving conductivity, the electron-accepting compound is preferably present in an amount of 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more, relative to the total functional material. On the other hand, if the content of the fluorine-containing electron-accepting compound is too high, the surface energy of the functional film decreases, making lamination difficult. Therefore, the electron-accepting compound is preferably present in an amount of 50% by weight or less, more preferably 30% by weight or less, and even more preferably 20% by weight or less, relative to the total functional material.

[0148] In addition, from the above viewpoint, the preferred content ratio of the charge transporting compound (preferably the sum of the charge transporting polymer compound and the charge transporting low molecular weight compound) to the electron accepting compound is charge transporting compound: electron accepting compound = 1:0.01~1, and particularly preferably 1:0.05~0.2.

[0149] [Preparation of functional ink] The functional ink of the present invention can be prepared by mixing a functional material with an organic solvent and heating it for a predetermined period of time to dissolve or disperse the functional material. 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, 100-115°C. Furthermore, the heating time is preferably 30 minutes or longer, more preferably 45 minutes or longer, and even more preferably 60 minutes or longer, for example, 60-180 minutes.

[0150] The heated functional ink is filtered through a membrane filter or depth filter to remove coarse particles before use. Considering the application of the functional ink by ejection from the nozzles of an inkjet head, the pore size 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.

[0151] [Film formation using a wet film forming method] The composition of the present invention is suitable for forming a functional film in the production of an organic electroluminescent device. The structure of the organic electroluminescent device is described below.

[0152] The organic electroluminescent element in the present invention typically has light-emitting pixels in tiny regions. These regions are formed by dividing a substrate provided with electrodes with liquid-repellent partition walls, called partition walls (banks). The functional ink of the present invention is sprayed into the tiny regions divided by the partition walls, dried, and then heated appropriately to form a functional film.

[0153] The ejection method is a method of ejecting droplets smaller than the micro-area defined by the partition layer from a micro-nozzle. Preferably, the functional ink of the present invention is filled with the micro-area defined by the partition layer by ejecting multiple droplets. The ejection method is preferably an inkjet method.

[0154] In the wet film-forming method, after filling the microscopic areas defined by banks with functional ink, the solvent is evaporated and dried using appropriate methods to produce a functional film. The evaporation and drying methods are not limited to the following and include heating and reduced-pressure drying. For example, reduced-pressure drying involves placing a substrate coated with the composition in an openable and closable metal or glass vacuum chamber and reducing the pressure within the chamber using a vacuum pump, thereby evaporating the solvent. Typical vacuum pumps include rotary oil pumps, mechanical booster pumps, dry scroll pumps, dry Roots pumps, turbomolecular pumps, and cryogenic pumps.

[0155] In order to appropriately take time to lower the pinning position of the functional ink and avoid the organic solvent from being in contact with the partition for too long, the time for drying the organic solvent contained in the functional ink under reduced pressure is preferably 1 minute or more and less than 15 minutes, more preferably 2 minutes or more and less than 12 minutes, and even more preferably 3 minutes or more and less than 10 minutes.

[0156] If it is the preferred boiling point range of the organic solvent in the present invention, it is possible to use the above-mentioned pump to fully volatilize it, but in order to further fully dry a trace of residual solvent, it is sometimes followed by heat drying. Further, in the presence of a charge transporting polymer compound or a low molecular weight compound, it is sometimes heated in order to crosslink the crosslinking groups possessed by functional materials such as electron accepting compounds. The heating process (hereinafter sometimes referred to as the roasting process) can also serve as the heating for crosslinking while drying. Heat drying serves as the heating for crosslinking, that is, drying and crosslinking are performed by heating, which is also preferred from the viewpoint of saving the number of steps. The heating temperature is preferably a temperature and time at which the functional film does not crystallize or condense.

[0157] The heating temperature of the functional material is usually 80°C or higher, preferably 100°C or higher, more preferably 150°C or higher, and more preferably 200°C or higher, and usually 300°C or lower, preferably 270°C or lower, and more preferably 240°C or lower. The heating time is usually 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer, and usually 120 minutes or shorter, preferably 90 minutes or shorter, and more preferably 60 minutes or shorter.

[0158] Heating can be performed using a hot plate, oven, infrared irradiation, or the like. In the case of infrared irradiation, which directly applies molecular vibrations, a heating time close to the aforementioned lower limit is sufficient. However, in the case of hot plate heating, where the substrate is in direct contact with the heat source or is positioned very close to the substrate, a longer time is required than with infrared irradiation. In the case of oven heating, i.e., heating using the gas within the oven, typically air or an inert gas such as nitrogen or argon, the temperature rise takes time, so a heating time close to the aforementioned upper limit is preferred. The heating time should be appropriately adjusted depending on the heating method.

[0159] It is important that the conditions for this heating process allow the cross-linking groups possessed by functional materials such as charge-transporting polymers and low-molecular-weight compounds to undergo cross-linking reactions with each other. Therefore, the heating temperature is preferably above the cross-linking starting temperature of the cross-linking groups possessed by the charge-transporting polymers, low-molecular-weight compounds, and electron-accepting compounds of the present invention when present.

[0160] Typically, during the drying process of the functional ink by volatilizing the solvent in the functional ink, the pinning position of the functional ink on the side of the bank decreases. However, if the drying is too fast, sufficient time will not be available to lower the pinning position, and the effect of the present invention may not be fully realized. Therefore, the time for the pressure of the atmosphere in the vacuum chamber during the reduced-pressure drying to reach the vapor pressure of the organic solvent with the lowest vapor pressure among the organic solvents contained in the functional ink of the present invention is preferably more than 60 seconds. On the other hand, when the functional ink is in continuous contact with the side of the bank, the problem of the material forming the bank gradually dissolving from the bank into the organic solvent of the functional ink will arise. Therefore, when the pressure of the atmosphere in the vacuum chamber during the reduced-pressure drying reaches a pressure lower than the vapor pressure of the organic solvent with the lowest vapor pressure among the organic solvents contained in the functional ink of the present invention, the time is preferably less than 900 seconds.

[0161] [Functional membrane] The functional film formed from the functional ink of the present invention is preferably a film in which crosslinking groups of the charge-transporting polymer compound and the low-molecular compound serving as the functional materials are crosslinked with each other. The functional material contained in the functional film is generally 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 most preferably substantially 100% by weight, with an upper limit of 100% by weight. Substantially 100% by weight means that the functional film sometimes contains trace amounts of additives, residual solvents, and impurities. By keeping the content of the functional material in the functional film within this range, the function of the functional material can be more effectively exerted.

[0162] [Layer Structure and Formation Method of Organic Electroluminescent Element] refer to Figure 3 , preferred examples of embodiments of the layer structure of an organic electroluminescent element produced using the production method of the present invention (hereinafter sometimes referred to as “the organic electroluminescent element of the present invention”) and a method for forming the same will be described.

[0163] Figure 3 1 is a schematic cross-sectional view showing a structural example of the organic electroluminescent element 10 of the present invention. Figure 3 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.

[0164] The organic electroluminescent element of the present invention has an anode, a light-emitting layer and a cathode as essential constituent layers, but may also have other layers as required, such as Figure 3 As shown, further functional layers may be present between the anode 2 and the light-emitting layer 5 and between the cathode 9 and the light-emitting layer 5 .

[0165] [Substrate] The substrate 1 is a support for the organic electroluminescent element. 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 are glass plates; plates of transparent synthetic resins such as polyester, polymethacrylate, polycarbonate, and polysulfone. When using a synthetic resin substrate, it is preferred to pay attention to the gas barrier properties. The gas barrier properties of the substrate are less likely to cause deterioration of the organic electroluminescent element due to external air passing through the substrate, so it is preferably large. Therefore, a method of providing a dense silicon oxide film or the like on at least one side of the synthetic resin substrate to ensure the gas barrier properties is also one of the preferred methods.

[0166] [anode] The anode 2 is an electrode that plays a role in injecting holes into the layer on the light-emitting layer 5 side. The anode 2 is usually composed of a metal such as aluminum, gold, silver, nickel, palladium, platinum, or an alloy of these metals with indium, copper, tellurium, palladium, or aluminum, a metal oxide such as indium and / or tin oxide, a metal halide such as copper iodide, carbon black, or a conductive polymer such as poly(3-methylthiophene), polypyrrole, or polyaniline.

[0167] The anode 2 is usually formed by a method such as sputtering or vacuum deposition. When the anode 2 is formed using metal particles such as silver, particles such as copper iodide, carbon black, conductive metal oxide particles, conductive polymer powder, etc., the anode 2 can also be formed by dispersing these particles in a suitable 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. Alternatively, the anode 2 may be formed by coating a conductive polymer on the substrate 1 (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

[0168] The anode 2 generally has a single-layer structure, but may also have a stacked structure composed of a plurality of materials as desired.

[0169] The thickness of the anode 2 can be appropriately selected based on the desired transparency, etc. When transparency is required, the visible light transmittance is generally set to 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is generally 5 nm or more, preferably 10 nm or more, and generally 1000 nm or less, preferably about 500 nm or less. When opacity is desired, the thickness of the anode 2 can be arbitrary. A substrate 1 that also functions as the anode 2 can be used. Different conductive materials can also be laminated on the anode 2.

[0170] In order to remove impurities adhering to the anode 2 and adjust the ionization potential to improve the hole injection property, the surface of the anode 2 is preferably subjected to ultraviolet (UV) / ozone treatment or oxygen plasma or argon plasma treatment.

[0171] [Pixel partition layer (partition wall layer)] The present invention includes the steps of applying a liquid-repellent resist on a substrate having a conductive electrode pattern and forming a plurality of openings in micro regions by photolithography. The method for applying the liquid-repellent resist can be exemplified by using a coating apparatus such as a roll coater, a reverse coater, a bar coater, a spin coater (spin coater), a die coater, or an inkjet printer on the substrate. If necessary, the solvent is removed by drying to form a liquid-repellent resist layer.

[0172] Next, in the exposure step, the liquid-repellent resist is irradiated with active energy rays such as ultraviolet rays or excimer laser light using a light shield, so that the liquid-repellent resist is partially exposed to the pattern corresponding to the pixel partition layer. As exposure using ultraviolet irradiation, a light source emitting ultraviolet rays such as a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, or a carbon arc lamp can be used. The exposure dose varies depending on the composition of the photosensitive resin composition, but is preferably 10 to 400 mJ / cm 2 about. In the case of a negative type lyophobic resist, the light shielding mask is formed by arranging light shielding portions of 10 to 500 μm in a linear or rectangular shape, thereby providing a pattern having a plurality of micro-region openings of 10 to 500 μm. Next, in the development step, the lyophobic resist exposed to the pattern corresponding to the pixel division layer is developed to form a pattern. The development method is not particularly limited, and immersion, spraying, and other methods can be used. Specific examples of developer solutions include organic developers such as dimethylbenzylamine, monoethanolamine, diethanolamine, and triethanolamine; and aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, and quaternary ammonium salts. A defoaming agent or surfactant may also be added to the developer solution.

[0173] The developed lyophobic resist is then post-baked and heat-cured to obtain a pixel partition layer. The post-baking is preferably performed at 150 to 250° C. for 15 to 60 minutes.

[0174] The substrate surface after patterning is treated with external energy to remove residues caused by resist coating or photoetching, etc. The external energy is preferably ultraviolet (UV) / ozone, oxygen plasma, plasma, etc.

[0175] From the perspective of film thickness uniformity, the taper angles of adjacent partition walls (banks) separated by a micro-region opening are preferably substantially the same. Substantially the same angle here means that the difference in taper angle is 5° or less, preferably 3° or less, more preferably 1° or less, and even more preferably 0°.

[0176] [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 the hole injection layer 3 is provided, the hole injection layer 3 is usually formed on the anode 2.

[0177] The hole injection layer 3 may be formed by vacuum deposition or wet film formation without particular limitation. From the perspective of reducing dark spots, the hole injection layer 3 is preferably formed by wet film formation. 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.

[0178] <Hole Transporting Materials> The hole injection layer-forming composition generally contains a hole transport material and a solvent as constituent materials of the hole injection layer 3 .

[0179] The hole-transporting material can be any hole-transporting compound commonly used in the hole injection layer 3 of an organic electroluminescent device. It can be a high-molecular-weight compound such as a polymer or a low-molecular-weight compound such as a monomer, but is preferably a high-molecular-weight compound. It should be noted that when the scope of application of the present invention is applied to the hole injection layer 3, the composition is characterized by comprising: a hole-transporting high-molecular-weight material having at least one cross-linking group with a weight-average molecular weight of 10,000 or greater, a hole-transporting low-molecular-weight material having at least one cross-linking group with a molecular weight of 5,000 or less, and at least one aromatic organic solvent.

[0180] The hole transport material is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a barrier to charge injection from the anode 2 to the hole injection layer 3. Examples of the hole transport material include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which a tertiary amine is linked to a fluorenyl group, hydrazone derivatives, silazane derivatives, silylamine derivatives, phosphamide derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylenevinylene derivatives, polythienylvinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, and carbon.

[0181] The derivatives of the present invention, such as aromatic amine derivatives, include aromatic amine itself and compounds with aromatic amine as the main skeleton, and can be polymers or monomers.

[0182] The hole transport material used as the material for the hole injection layer 3 may contain any one of these compounds alone or two or more thereof. When containing two or more hole transport materials, any combination thereof is acceptable, but it is preferred to use one or more aromatic tertiary amine polymer compounds in combination with one or more other hole transport materials.

[0183] Among the hole transport materials listed above, aromatic amine compounds are preferred from the perspective of amorphousness and visible light transmittance, and aromatic tertiary amine compounds are particularly preferred. Aromatic tertiary amine compounds refer to compounds having an aromatic tertiary amine structure, including compounds having a group derived from an aromatic tertiary amine.

[0184] The type of aromatic tertiary amine compound is not particularly limited, but from the perspective of uniform luminescence due to the surface smoothing effect, a polymer compound (a polymeric compound in which repeating units are linked) having a weight average molecular weight of 1,000 to 1,000,000 is more preferred. 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).

[0185] [Chemistry 1]

[0186] (In formula (1), Ar 3 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, Ar 4 represents a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which a plurality of such aromatic hydrocarbon groups and aromatic heterocyclic groups are linked directly or via a linking group)

[0187] In the aforementioned 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, and examples thereof include: a group formed by connecting 1 to 30, preferably 1 to 5, and more preferably 1 to 3 groups selected from -O- group, -C(=O)- group and -CH2- group (which may have a substituent) in any order. Among the linking groups, Ar in formula (1) is preferred from the viewpoint of excellent hole injection into the light-emitting layer. 4 A plurality of aromatic hydrocarbon groups or aromatic heterocyclic groups are linked via a linking group represented by the following formula (2).

[0188] [Chemistry 2]

[0189] (In formula (2), y1 represents an integer from 1 to 10, R 8and R 9 Each independently represents a hydrogen atom or an alkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. In the presence of multiple R 8 、R 9 In the case of , they may be the same or different)

[0190] [Chemistry 3]

[0191] In the above formula (11), x1, x2, x3, x4, x5, and x6 each independently represent an integer greater than or equal to 0. However, x3+x4≧1. 11 、Ar 12 、Ar 14 Each independently represents a divalent aromatic ring group having 30 or less carbon atoms which may have a substituent. 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), Q 11 , Q 12 Each independently represents an oxygen atom, a sulfur atom, a hydrocarbon chain having 6 or less carbon atoms which may have a substituent, S 1 ~S 4 Each independently represents a group represented by the following formula (13). It should be noted that the aromatic ring group mentioned here refers to an aromatic hydrocarbon group and an aromatic heterocyclic group.

[0192] As Ar 11 、Ar 12 、Ar 14 Examples of the aromatic ring group include: a monocyclic ring, a two- to six-membered condensed ring, or a group formed by connecting two or more of these aromatic rings. Specific examples of the monocyclic or two- to six-membered condensed ring aromatic ring group include divalent groups derived from the following: benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzopyrene ring, ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, a biphenyl, a terphenyl, a quaterphenyl, a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a phenanthridine ring, a quinazoline ring, a quinazolinone ring or an azulene ring. Among them, 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 is preferred from the viewpoint of efficiently delocalizing negative charges and having excellent stability and heat resistance. As Ar 13 Examples of aromatic ring groups, with Ar 11 、Ar 12 、Ar 14 Same time.

[0193] [Chemistry 4]

[0194] 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, which may have a substituent. 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, which may have a substituent. 31 represents a monovalent aromatic ring group or a monovalent cross-linking group, which may have a substituent. x7 represents 1 to 4. When x7 is 2 or more, multiple R 12 Can be the same or different, multiple Ar 31 They may be the same or different. An asterisk (*) indicates a bonding site to the nitrogen atom in formula (11).

[0195] As R 11 The aromatic ring group is preferably a monocyclic or condensed aromatic ring group having 3 to 30 carbon atoms or a group formed by connecting 2 to 6 of these. Specific examples include trivalent groups derived from the following: a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a group formed by connecting 2 to 6 of these. As R 11 The alkyl group is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and specific examples thereof include groups derived from methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane and octane. As R 11 The group composed of an alkyl group having 40 or less carbon atoms and an aromatic ring group can preferably be mentioned as a group composed of a group consisting of a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms and 1 or 2 to 6 monocyclic or condensed aromatic ring groups having 3 to 30 carbon atoms.

[0196] As R 12 Specific examples of the aromatic ring group include divalent groups derived from a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a connected ring having 30 or less carbon atoms formed by connecting these rings. As R 12Specific examples of the alkyl group include divalent groups derived from methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane, and octane.

[0197] As Ar 31 Specific examples of the aromatic ring group include monovalent groups derived from a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a linked ring having 30 or less carbon atoms formed by linking these rings.

[0198] As an example of a preferred structure of formula (12), the following structures can be cited as R 11 The benzene ring or fluorene ring in the main chain in the following structure of the partial structure may further have a substituent.

[0199] [Chemistry 5]

[0200] As Ar 31 Examples of the crosslinking group include a group derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, an acrylic group, etc. From the perspective of compound stability, a group derived from a benzocyclobutene ring or a naphthocyclobutene ring is preferred.

[0201] [Chemistry 6]

[0202] In the above formula (13), x and y represent integers greater than or equal to 0. 21 、Ar 23 Each independently represents a divalent aromatic ring group, which may have a substituent. 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, which may have a substituent. 32 represents a monovalent aromatic ring group or a monovalent crosslinking group, and these groups may have a substituent. An asterisk (*) represents a bonding site to the nitrogen atom in formula (11).

[0203] As Ar 21 、Ar 23 Examples of aromatic ring groups, with Ar 11 、Ar 12 、Ar 14 The same situation.

[0204] As Ar 22 、Ar 32Examples of aromatic ring groups include: a monocyclic ring, a two- to six-membered condensed ring, or a group formed by connecting two or more of these aromatic rings. Specific examples include monovalent groups derived from the following: benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzopyrene ring, ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, a biphenyl, a terphenyl, a quaterphenyl, a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a phenanthridine ring, a quinazoline ring, a quinazolinone or an azulene ring. Among them, 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 is preferred from the viewpoint of efficiently delocalizing negative charges and having excellent stability and heat resistance.

[0205] As R 13 Examples of alkyl or aromatic ring groups, with R 12 same.

[0206] Ar 32 The crosslinking group is not particularly limited, but preferred examples include a group derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, and an acrylic group.

[0207] As long as it does not violate the purpose of the present invention, the above Ar 11 ~Ar 14 、R 11 ~R 13 、Ar 21 ~Ar 23 、Ar 31 ~Ar 32 , Q 11 , Q 12 Each of the substituents may further have a substituent. The molecular weight of the substituent is preferably 400 or less, more preferably 250 or less. The type of the substituent is not particularly limited, and examples thereof include one or more substituents selected from the following substituent group W.

[0208] [Substituent Group W] an alkyl group having 1 or more carbon atoms, preferably 10 or less, and more preferably 8 or less, such as a methyl group and an ethyl group; an alkenyl group having 2 or more carbon atoms, preferably 11 or less, and more preferably 5 or less, such as a vinyl group; an alkynyl group having 2 or more carbon atoms, preferably 11 or less, and more preferably 5 or less, such as an ethynyl group; an alkoxy group having 1 or more carbon atoms, preferably 10 or less, and more preferably 6 or less, such as a methoxy group and an ethoxy group; an aryloxy group having 4 or more carbon atoms, preferably 5 or more, preferably 25 or less, and more preferably 14 or less, such as a phenoxy group, a naphthoxy group, and a pyridyloxy group; a methyl Alkoxycarbonyl groups having 2 or more carbon atoms, preferably 11 or less, and more preferably 7 or less, such as oxycarbonyl and ethoxycarbonyl; dialkylamino groups having 2 or more carbon atoms, preferably 20 or less, and more preferably 12 or less, such as dimethylamino and diethylamino; diarylamino groups having 10 or more carbon atoms, preferably 12 or more, preferably 30 or less, and more preferably 22 or less, such as diphenylamino, ditolylamino and N-carbazolyl; and groups having 6 or more carbon atoms, more preferably 7 or more, preferably 25 or less, and more preferably 17 or less, such as phenylmethylamino. an acyl group having 2 or more carbon atoms, preferably 10 or less, more preferably 7 or less, such as an acetyl group and a benzoyl group; a halogen atom such as a fluorine atom and a chlorine atom; a haloalkyl group having 1 or more carbon atoms, preferably 8 or less, more preferably 4 or less, such as a trifluoromethyl group; an alkylthio group having 1 or more carbon atoms, preferably 10 or less, more preferably 6 or less, such as a methylthio group and an ethylthio group; an arylthio group having 4 or more carbon atoms, preferably 5 or more, preferably 25 or less, more preferably 14 or less, such as a phenylthio group, a naphthylthio group, a pyridylthio group; a trimethylsilyl group, a triphenylthio group, a silyl groups having 2 or more, preferably 3 or more, preferably 33 or less, and more preferably 26 or less carbon atoms, such as methylsilyl; siloxy groups having 2 or more, preferably 3 or more, preferably 33 or less, and more preferably 26 or less carbon atoms, such as trimethylsilyloxy and triphenylsilyloxy; cyano group; aromatic hydrocarbon groups having 6 or more, preferably 30 or less, and more preferably 18 or less carbon atoms, such as phenyl and naphthyl; aromatic heterocyclic groups having 3 or more, preferably 4 or more, preferably 28 or less, and more preferably 17 or less carbon atoms, such as thienyl and pyridyl.

[0209] Among the above-mentioned substituent group W, an alkyl group or an alkoxy group is preferred from the viewpoint of improving solubility, and an aromatic hydrocarbon group or an aromatic heterocyclic group is preferred from the viewpoint of charge transportability and stability.

[0210] Among the polymer compounds having a repeating unit represented by the formula (11), polymer compounds having a repeating unit represented by the following formula (14) are particularly preferred because they have very high hole injection / transport properties.

[0211] [Chemistry 7]

[0212] In the above formula (14), R 21 ~R 25 Each independently represents an arbitrary substituent. 21 ~R 25 Specific examples of the substituent are the same as the substituents described in the aforementioned [Substituent Group W]. 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.

[0213] Preferred examples of the aromatic tertiary amine polymer compound include polymer compounds containing repeating units represented by the following formula (15) and / or formula (16).

[0214] [Chemistry 8]

[0215] In the above formula (15) and formula (16), Ar 45 、Ar 47 and Ar 48 Each independently represents a monovalent aromatic hydrocarbon group which may have a substituent or a monovalent aromatic heterocyclic group which may have a substituent. 44 and Ar 46 Each independently represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. 41 ~R 43 Each independently represents a hydrogen atom or an arbitrary substituent.

[0216] Ar 45 、Ar 47 and Ar 48 Specific examples, preferred examples, examples of substituents that may be possessed and preferred examples of substituents are the same as Ar 22 Same, Ar 44 and Ar 46 Specific examples, preferred examples, examples of substituents that may be possessed and preferred examples of substituents are the same as Ar 11 、Ar 12 and Ar 14 Same as R 41 ~R 43 It is preferably a hydrogen atom or a substituent described in the aforementioned [Substituent Group W], and more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group, or an aromatic heterocyclic group.

[0217] Preferred specific examples of the repeating units represented by formula (15) and formula (16) that can be applied to the present invention are listed below, but the present invention is not limited to these.

[0218] [Chemistry 9]

[0219] <Electron-Accepting Compound> The hole injection layer-forming composition preferably contains an electron-accepting compound as a constituent material of the hole injection layer 3 .

[0220] The electron-accepting compound is preferably a compound having oxidizing power and the ability to accept one electron from the hole transport material. Specifically, the electron-accepting compound is preferably a compound having an electron affinity of 4.0 eV or greater, more preferably 5.0 eV or greater.

[0221] Examples of such electron-accepting compounds include one or more compounds selected from triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of aromatic amines and metal halides, and salts of aromatic amines and Lewis acids. Furthermore, specifically, examples of electron-accepting compounds include: organic-substituted onium salts such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and triphenylsulfonium tetrafluoroborate (International Publication No. 2005 / 089024, International Publication No. 2017 / 164268); high-valence inorganic compounds such as iron (III) chloride (Japanese Patent Publication No. 11-251067) and ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris(pentafluorophenyl)borane (Japanese Patent Publication No. 2003-31365); fullerene derivatives; iodine; sulfonate ions such as polystyrenesulfonate ion, alkylbenzenesulfonate ion, and camphorsulfonate ion; and the like.

[0222] The electron-accepting compound can increase the conductivity of the hole injection layer 3 by oxidizing the hole transport material.

[0223] <Other constituent materials> The material of the hole injection layer 3 may contain other components in addition to the above-mentioned hole transport material or electron accepting compound, unless the effects of the present invention are significantly impaired.

[0224] <Solvent> At least one of the solvents in the hole injection layer-forming composition used in the wet film-forming method is preferably a compound capable of dissolving the constituent materials of the hole injection layer 3 .

[0225] Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents.

[0226] Examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); and aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, 3-phenoxytoluene, diphenyl ether, and dibenzyl ether.

[0227] Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, isobutyl benzoate, amyl benzoate, isoamyl benzoate, methyl benzoate, ethyl benzoate, methyl anisate, ethyl anisate, dimethyl phthalate, diethyl phthalate, phenoxyethyl acetate, and phenoxyethyl butyrate.

[0228] Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, trimethylbenzene, tetramethylbenzene, diisopropylbenzene, triisopropylbenzene, methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, diisopropylnaphthalene, ethylbiphenyl, isopropylbiphenyl, butylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, tetralin, 1,1-diphenylethane, 1,1-diphenylpropane, 1,1-diphenylbutane, 1,1-diphenylpentane, and 1,1-diphenylhexane.

[0229] Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide. In addition, dimethyl sulfoxide or the like can also be used. Among them, aromatic esters and aromatic ethers are preferred.

[0230] These solvents may be used alone or in combination of two or more in any combination and ratio.

[0231] As long as the effect of the present invention is not significantly damaged, the concentration of the hole transport material in the hole injection layer forming composition is arbitrary. From the perspective of the uniformity of the film thickness, the concentration of the hole transport material in the hole injection layer forming composition is preferably 0.01 weight % or more, more preferably 0.1 weight % or more, and further preferably 0.5 weight % or more. The concentration of the hole transport material in the hole injection layer forming composition is preferably 70 weight % or less, more preferably 60 weight % or less, and further preferably 50 weight % or less. From the perspective of not being easy to produce uneven film thickness, it is preferred that the concentration is small. In addition, from the perspective of not being easy to produce defects in the hole injection layer of film formation, it is preferred that the concentration is large.

[0232] <Formation of Hole Injection Layer by Wet Film Formation> When the hole injection layer 3 is formed by a wet film-forming method, the material constituting the hole injection layer 3 is usually mixed with an appropriate solvent (a solvent for the hole injection layer) to prepare a film-forming composition (a composition for forming the hole injection layer). The composition for forming the hole injection layer 3 is applied to a layer corresponding to the lower layer of the hole injection layer (usually the anode 2) by an appropriate method to form a film, and then dried to form the hole injection layer 3.

[0233] [Hole Transport Layer] The hole transport layer 4 is a layer that transports holes from the anode 2 to the light-emitting layer 5. Although the hole transport layer 4 is not an essential layer in the organic electroluminescent element of the present invention, when the hole transport layer 4 is provided, the hole transport layer 4 is usually formed on the hole injection layer 3 when the hole injection layer 3 is present, and is formed on the anode 2 when the hole injection layer 3 is not present.

[0234] The hole transport layer 4 may be formed by vacuum deposition or wet film formation without particular limitation. From the perspective of reducing dark spots, the hole transport layer 4 is preferably formed by wet film formation.

[0235] The material forming the hole transport layer 4 is preferably a material with high hole transport properties and capable of efficiently transporting injected holes. To this end, the material forming the hole transport layer 4 preferably has a low ionization potential, high transparency to visible light, high hole mobility, excellent stability, and is not prone to the formation of impurities that become traps during manufacturing or use. In most cases, the hole transport layer 4 is in contact with the light-emitting layer 5, so it is preferred not to quench the light from the light-emitting layer 5 or to not form an exciplex with the light-emitting layer 5, which would reduce efficiency.

[0236] The material for the hole transport layer 4 may be any material that has been conventionally used as a constituent material of the hole transport layer 4. Examples of the material for the hole transport layer 4 include aromatic amine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed-ring polycyclic aromatic derivatives, and metal complexes.

[0237] 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, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophene derivatives, and poly(p-phenylene vinylene) derivatives. These materials may be alternating copolymers, random polymers, block polymers, or graft copolymers. Furthermore, they may be polymers having three or more branches at the end of the main chain, or so-called dendrimers.

[0238] Among them, the material of the hole transport layer 4 is preferably a polyarylamine derivative or a polyarylene derivative. Specific examples of the polyarylamine derivatives and the polyarylene derivatives include those described in JP-A-2008-98619. As the polyarylamine derivative, the aforementioned aromatic tertiary amine polymer compound is preferably used.

[0239] When the hole transport layer 4 is formed by a wet film formation 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 , and the composition is wet-formed and then dried. The hole transport layer-forming composition contains, in addition to the aforementioned hole transport material, a solvent. The solvent used is the same as that used in the hole injection layer-forming composition. Furthermore, the film formation and drying conditions are the same as those used for forming the hole injection layer 3. When the hole transport layer-forming composition is the composition of the present invention, the solvent is the first solvent and the second solvent of the present invention. When the hole transport layer 4 is formed by vacuum deposition, the film formation conditions and the like are the same as those for forming the hole injection layer 3 described above.

[0240] Taking into account factors such as infiltration of low molecular weight materials in the light-emitting layer and swelling of the hole transport material, 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 200 nm or less.

[0241] [Luminous layer] The light-emitting layer 5 is a layer that becomes the main light source by being excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between the electrodes under an electric field. The light-emitting layer 5 is generally formed on the hole transport layer 4 when the hole transport layer 4 is present; on the hole injection layer 3 when the hole transport layer 4 is absent but the hole injection layer 3 is present; and on the anode 2 when neither the hole transport layer 4 nor the hole injection layer 3 is present.

[0242] <Materials for Light-Emitting Layer> The material for the light-emitting layer generally contains a light-emitting material and a charge-transporting material as a main component.

[0243] <Luminescent Materials> As the luminescent material, any known material used as a luminescent material for an organic electroluminescent element can be used, without particular limitation, as long as a substance that emits light at the desired emission wavelength and has good luminous efficiency is used. The luminescent material can be a fluorescent material or a phosphorescent material, but is preferably a phosphorescent material from the perspective of internal quantum efficiency. It is further preferred that the red luminescent material and the green luminescent material be phosphorescent materials, and the blue luminescent material be a fluorescent material.

[0244] 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-transporting materials.

[0245] <Phosphorescent Materials> Phosphorescent materials are materials that emit light from an excited triplet state. Representative examples include metal complex compounds containing Ir, Pt, Eu, and the like. The material preferably contains a metal complex.

[0246] Among metal complexes, examples of phosphorescent organometallic complexes that emit light via the triplet state include Werner-type complexes or organometallic complex compounds containing a metal selected from Groups 7 to 11 of the long-periodic periodic table (hereinafter, unless otherwise specified, "periodic table" refers to the long-periodic periodic table) as a central metal. Examples of such phosphorescent materials include those described in International Publication Nos. 2014 / 024889, 2015 / 087961, 2016 / 194784, and JP-A-2014-074000. Preferably, the compound is represented by the following formula (201) or the following formula (205), and more preferably, the compound is represented by the following formula (201).

[0247] [Chemistry 10]

[0248] 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 、R 102 Each independently represents a structure represented by formula (202), and "*" represents a bonding position to ring A1 or ring A2. 101 、R 102 Can be the same or different, in R 101 、R 102 When there are plural of each, they may be the same or different.

[0249] Ar 201 、Ar 203 Each independently represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent. Ar 202 It represents an aromatic hydrocarbon ring structure which may have a substituent, an aromatic heterocyclic structure which may have a substituent, or an aliphatic hydrocarbon structure which may have a substituent. 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.

[0250] B 201 -L 200 -B 202 Indicates an anionic bidentate ligand. B 201 and B 202 Each independently represents a carbon atom, an oxygen atom or a nitrogen atom, which may also be a ring-forming atom. 200 Represents a single bond or with B 201 and B 202 Together they form a bidentate ligand. 201 -L 200 -B 202 , they may be the same or different.

[0251] It should be noted that in formulas (201) and (202), i1 and i2 each independently represent an integer from 0 to 12, i3 indicates that it can replace Ar 202 The number of is an integer greater than 0, i4 indicates that it can replace Ar 201 The number of is an integer greater than 0, k1 and k2 each independently represent an integer greater than or equal to 0, with the number of rings that can be substituted for ring A1 and ring A2 being the upper limit. z represents an integer of 1 to 3.

[0252] (Substituent) Unless otherwise specified, the substituent is preferably a group selected from the following substituent group S.

[0253] <Substituent Group S> The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, further preferably an alkyl group having 1 to 8 carbon atoms, and particularly preferably an alkyl group having 1 to 6 carbon atoms. The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and still more preferably an alkoxy group having 1 to 6 carbon atoms. The aryloxy group is preferably an aryloxy group having 6 to 20 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, further preferably an aryloxy group having 6 to 12 carbon atoms, and particularly preferably an aryloxy group having 6 carbon atoms. The heteroaryloxy group is preferably a heteroaryloxy group having 3 to 20 carbon atoms, and more preferably a heteroaryloxy group having 3 to 12 carbon atoms. The alkylamino group is preferably an alkylamino group having 1 to 20 carbon atoms, and more preferably an alkylamino group having 1 to 12 carbon atoms. The arylamino group is preferably an arylamino group having 6 to 36 carbon atoms, and more preferably an arylamino group having 6 to 24 carbon atoms. The aralkyl group is preferably an aralkyl group having 7 to 40 carbon atoms, more preferably an aralkyl group having 7 to 18 carbon atoms, and even more preferably an aralkyl group having 7 to 12 carbon atoms. The heteroaralkyl group is preferably a heteroaralkyl group having 7 to 40 carbon atoms, and more preferably a heteroaralkyl group having 7 to 18 carbon atoms. The alkenyl group is preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, further preferably an alkenyl group having 2 to 8 carbon atoms, and particularly preferably an alkenyl group having 2 to 6 carbon atoms. Alkynyl group, preferably an alkynyl group having 2 to 20 carbon atoms, more preferably an alkynyl group having 2 to 12 carbon atoms. The aryl group is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, further preferably an aryl group having 6 to 18 carbon atoms, and particularly preferably an aryl group having 6 to 14 carbon atoms. The heteroaryl group is preferably a heteroaryl group having 3 to 30 carbon atoms, more preferably a heteroaryl group having 3 to 24 carbon atoms, further preferably a heteroaryl group having 3 to 18 carbon atoms, and particularly preferably a heteroaryl group having 3 to 14 carbon atoms. The alkylsilyl group is preferably an alkylsilyl group having 1 to 20 carbon atoms, and more preferably an alkylsilyl group having 1 to 12 carbon atoms. The arylsilyl group is preferably an arylsilyl group having 6 to 20 carbon atoms, and more preferably an arylsilyl group having 6 to 14 carbon atoms. - Alkylcarbonyl group, preferably an alkylcarbonyl group having 2 to 20 carbon atoms. The arylcarbonyl group is preferably an arylcarbonyl group having 7 to 20 carbon atoms.

[0254] In the above groups, one or more hydrogen atoms may be substituted by fluorine atoms, or one or more hydrogen atoms may be substituted by deuterium atoms. Unless otherwise specified, an aryl group is an aromatic hydrocarbon ring, and a heteroaryl group is an aromatic heterocycle. ·Hydrogen atom, heavy hydrogen atom, fluorine atom, cyano group or -SF5.

[0255] Among the above-mentioned substituent group S, preferably, alkyl, alkoxy, aryloxy, arylamino, aralkyl, alkenyl, aryl, heteroaryl, alkylsilyl, arylsilyl, and groups in which one or more hydrogen atoms of these groups are substituted with fluorine atoms, fluorine atoms, cyano or -SF5, More preferably, it is an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, a group in which one or more hydrogen atoms of these groups are substituted by a fluorine atom, a fluorine atom, a cyano group or -SF5, More preferably, they are alkyl, alkoxy, aryloxy, arylamino, aralkyl, alkenyl, aryl, heteroaryl, alkylsilyl, and arylsilyl. Particularly preferred are alkyl, arylamino, aralkyl, alkenyl, aryl, and heteroaryl. Most preferred are alkyl, arylamino, aralkyl, aryl, and heteroaryl.

[0256] These substituent groups S may further have a substituent selected from the substituent group S. Preferred groups, more preferred groups, further preferred groups, particularly preferred groups, and most preferred groups of the substituents that may be present are the same as the preferred groups in the substituent group S.

[0257] (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.

[0258] 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 triphenylyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring are preferred.

[0259] 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 heteroatom, and more preferably a furan ring, a benzofuran ring, a thiophene ring, or 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.

[0260] (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 heteroatom. Specific examples include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, and a phenanthridine ring. Preferred are pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, benzothiazole ring, benzoxazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, and quinazoline ring. More preferred are pyridine ring, imidazole ring, benzothiazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, and quinazoline ring. Most preferred are pyridine ring, imidazole ring, benzothiazole ring, quinoline ring, quinoxaline ring, and quinazoline ring.

[0261] (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-oxadiazole ring) and (benzene ring-thiophene ring).

[0262] (Substituents of Ring A1 and Ring A2) The substituent that Ring A1 and Ring A2 may have can be arbitrarily selected, but is preferably one or more substituents selected from the aforementioned substituent group S.

[0263] (Ar 201 、Ar 202 、Ar 203 ) Ar 201 、Ar 203 Each independently represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent. Ar 202 It represents an aromatic hydrocarbon ring structure which may have a substituent, an aromatic heterocyclic structure which may have a substituent, or an aliphatic hydrocarbon structure which may have a substituent.

[0264] Ar 201 、Ar 202 、Ar 203 When any one of the above is an aromatic hydrocarbon ring structure which may have a substituent, the aromatic hydrocarbon ring structure is preferably an aromatic hydrocarbon ring having 6 to 30 carbon atoms. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring is preferred, a benzene ring, a naphthalene ring, or a fluorene ring is more preferred, and a benzene ring is most preferred.

[0265] Ar 201 、Ar 202When any one of them is a benzene ring which may have a substituent, it is preferred that at least one benzene ring is bonded to the adjacent structure at the ortho position or the meta position, and it is more preferred that at least one benzene ring is bonded to the adjacent structure at the meta position.

[0266] Ar 201 、Ar 202 、Ar 203 When any one of them is a fluorene ring which may have a substituent, the 9-position and the 9'-position of the fluorene ring preferably have a substituent or are bonded to an adjacent structure.

[0267] Ar 201 、Ar 202 、Ar 203 When any one of the is an aromatic heterocyclic structure which may have a substituent, the aromatic heterocyclic structure is preferably an aromatic heterocyclic ring having 3 to 30 carbon atoms and containing any one of a nitrogen atom, an oxygen atom or a sulfur atom as a heteroatom. Specifically, examples include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a 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, the pyridine ring, the pyrimidine ring, the triazine ring, the carbazole ring, the dibenzofuran ring, and the dibenzothiophene ring are used.

[0268] Ar 201 、Ar 202 、Ar 203 When any one of them is a carbazole ring which may have a substituent, it is preferred that the N position of the carbazole ring has a substituent or is bonded to an adjacent structure.

[0269] Ar 202 When it is an aliphatic hydrocarbon structure which 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 1 to 12 carbon atoms, and even more preferably 1 to 8 carbon atoms.

[0270] (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. Within this range, improvement in solubility or charge transport properties can be expected. i3 preferably represents an integer of 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1. i4 preferably represents an integer of 0 to 2, and more preferably 0 or 1. k1 and k2 each independently represent an integer of preferably 0 to 3, more preferably 1 to 3, further preferably 1 or 2, and particularly preferably 1.

[0271] (Ar201 、Ar 202 、Ar 203 Preferred substituents of Ar 201 、Ar 202 、Ar 203 The substituents that may be present may be arbitrarily selected, but are preferably one or more substituents selected from the aforementioned substituent group S. Preferred groups are also as shown in the aforementioned substituent group S, but are more preferably unsubstituted (hydrogen atom), alkyl, aryl, particularly preferably unsubstituted (hydrogen atom), alkyl, most preferably unsubstituted (hydrogen atom) or tert-butyl, preferably tert-butyl in the presence of Ar 203 When substituted with Ar 203 , in the absence of Ar 203 When substituted with Ar 202 , in the absence of Ar 202 and Ar 203 When substituted with Ar 201 .

[0272] (Preferred embodiment of the compound represented by formula (201)) The compound represented by the above formula (201) is preferably a compound that satisfies any one or more of the following (I) to (IV).

[0273] (I) Phenylene connection formula The structure represented by formula (202) is preferably a structure having a group formed by connecting benzene rings, that is, a benzene ring structure, i1 is 1 to 6, and at least one of the aforementioned benzene rings is bonded to an adjacent structure at the ortho position or the meta position. With such a structure, it is expected that the solubility is improved and the charge transport property is improved.

[0274] (II) (phenylene)-aralkyl (alkyl) Ring A1 or A2 has a structure in which an alkyl group or an aralkyl group is bonded to an aromatic hydrocarbon group or an aromatic heterocyclic group, that is, Ar 201 is an aromatic hydrocarbon structure or an aromatic heterocyclic structure, i1 is 1 to 6, Ar 202 is an aliphatic hydrocarbon structure, i2 is 1 to 12, preferably 3 to 8, Ar 203 A benzene ring structure, i3 is 0 or 1, preferably Ar 201 The aromatic hydrocarbon structure is more preferably a structure in which 1 to 5 benzene rings are connected, and more preferably a structure in which 1 benzene ring is connected. With such a structure, it is expected that the solubility is improved and the charge transport property is improved.

[0275] (III) Dendrites A structure in which a dendron is bonded to ring A1 or ring A2, for example, Ar 201 、Ar 202Benzene ring structure, Ar 203 It is a biphenyl or terphenyl structure, i1 and i2 are 1 to 6, i3 is 2, and j is 2. With such a structure, it is expected that the solubility is improved and the charge transport property is improved.

[0276] (IV)B 201 -L 200 -B 202 By B 201 -L 200 -B 202 The structure represented is preferably a structure represented by the following formula (203) or the following formula (204).

[0277] [Chemistry 11]

[0278] In formula (203), R 211 、R 212 、R 213 Each independently represents 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.

[0279] (Preferred phosphorescent material) The phosphorescent material represented by the above formula (201) is not particularly limited, but the following materials can be cited as preferred materials.

[0280] [Chemistry 12]

[0281] [Chemistry 13]

[0282] In addition, a phosphorescent material represented by the following formula (205) is also preferred.

[0283] [Chemistry 14]

[0284] [In formula (205), M 2 R represents a metal, and T represents a carbon atom or a nitrogen atom. 92 ~R 95 Each independently represents a substituent. When T is a nitrogen atom, there is no R 94 and R 95 . ]

[0285] In formula (205), as M 2Specific examples include metals selected from Groups 7 to 11 of the periodic table. Among them, preferably, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is used, and particularly preferably, divalent metals such as platinum and palladium are used.

[0286] In addition, in formula (205), R 92 and R 93 Each independently represents 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, 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.

[0287] Moreover, when T is a carbon atom, R 94 and R 95 Each independently represents the 92 and R 93 In addition, when T is a nitrogen atom, there is no R directly bonded to the T. 94 or R 95 In addition, R 92 ~R 95 It may also have a substituent. As a substituent, it may be the substituent mentioned above. Further, R 92 ~R 95 Any two or more groups in the group may be linked to form a ring.

[0288] (Molecular weight) The molecular weight of the phosphorescent material is preferably 5000 or less, more preferably 4000 or less, and particularly preferably 3000 or less. Furthermore, the molecular weight of the phosphorescent material is preferably 800 or more, more preferably 1000 or more, and even more preferably 1200 or more. It is believed that within this molecular weight range, a light-emitting layer can be obtained in which the phosphorescent material is uniformly mixed with the charge transport material without agglomeration, and thus has high luminous efficiency.

[0289] The phosphorescent material preferably has a large molecular weight because it has a high Tg, melting point, decomposition temperature, and other factors, resulting in excellent heat resistance of the phosphorescent material and the resulting light-emitting layer, and is less likely to experience degradation of film quality due to gas generation, recrystallization, and molecular migration, or an increase in impurity concentration associated with thermal decomposition of the material. On the other hand, the phosphorescent material preferably has a small molecular weight because it facilitates purification of the organic compound.

[0290] <Charge Transporting Materials> The charge transport material used in the light emitting layer is a material having a skeleton with excellent charge transport properties, and is preferably selected from electron transport materials, hole transport materials, and bipolar materials capable of transporting both electrons and holes.

[0291] Specific examples of skeletons having 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, fluorene structures, quinacridone structures, triphenylene structures, carbazole structures, pyrene structures, anthracene structures, phenanthroline structures, quinoline structures, pyridine structures, pyrimidine structures, triazine structures, oxadiazole structures, and imidazole structures.

[0292] As the electron transport material, from the viewpoint of excellent electron transport properties and a relatively stable structure, a compound having a pyridine structure, a pyrimidine structure, or a triazine structure is more preferable, and a compound having a pyrimidine structure or a triazine structure is even more preferable.

[0293] The hole transport material is a compound having a structure with excellent hole transport properties. Among the aforementioned central skeletons with excellent charge transport 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, a dibenzofuran structure or a triarylamine structure is further preferred.

[0294] The charge transport material used in the light-emitting layer preferably has a fused ring structure of three or more rings, and more preferably a compound having two or more fused ring structures of three or more rings or a compound having at least one fused ring of five or more rings. By using these compounds, the rigidity of the molecule is increased, and the effect of suppressing the degree of molecular motion of the thermal response is easily obtained. Furthermore, from the aspects of charge transportability and durability of the material, the fused rings of three or more rings and the fused rings of five or more rings preferably have aromatic hydrocarbon rings or aromatic heterocycles.

[0295] Specific examples of the fused ring structure having three or more rings include anthracene structure, phenanthrene structure, pyrene structure, The structure of the present invention may be a tetracene structure, a triphenylene structure, a fluorene structure, a benzofluorene structure, an indenofluorene structure, an indolofluorene structure, a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, a dibenzothiophene structure, etc. From the viewpoint of charge transport and solubility, at least one structure 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 is preferred. From the viewpoint of durability against charge, a carbazole structure or an indolocarbazole structure is more preferred.

[0296] In the present invention, from the viewpoint of durability against charge of the organic electroluminescent element, it is preferred that at least one of the charge-transporting materials of the light-emitting layer is a material having a pyrimidine skeleton or a triazine skeleton.

[0297] From the viewpoint of excellent flexibility, the charge transport material of the light-emitting layer is preferably a polymer material. The light-emitting layer formed using a material with excellent flexibility is preferably used as the light-emitting layer of an organic electroluminescent element formed on a flexible substrate. When the charge transport material contained in the light-emitting layer is a polymer 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 further preferably 10,000 or more and 100,000 or less.

[0298] Furthermore, the charge-transporting material for the light-emitting layer is preferably a low molecular weight material from the perspectives of ease of synthesis and purification, ease of designing electron and hole transport properties, and ease of viscosity adjustment when dissolved in a solvent. When the charge-transporting 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, preferably 300 or more, more preferably 350 or more, and even more preferably 400 or more.

[0299] <Fluorescent Materials> The fluorescent material is not particularly limited, but is preferably a compound represented by the following formula (211).

[0300] [Chemistry 15]

[0301] In the above formula (211), Ar 241 represents an aromatic hydrocarbon condensed ring structure which may have a substituent, Ar 242 、Ar 243 Each independently represents an alkyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, or a group formed by bonding these groups. n41 is an integer of 1 to 4.

[0302] Ar 241 It preferably represents an aromatic hydrocarbon condensed ring structure having 10 to 30 carbon atoms, and specific examples of the ring structure include naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, tetracene, Perylene, etc. Ar 241 More preferably, it is an aromatic hydrocarbon condensed ring structure having 12 to 20 carbon atoms. Specific examples of the ring structure include acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, tetracene, Perylene. Ar 241 More preferably, it is an aromatic hydrocarbon condensed ring structure having 16 to 18 carbon atoms. Specific examples of the ring structure include fluoranthene, pyrene,

[0303] n41 is 1 to 4, preferably 1 to 3, more preferably 1 to 2, and most preferably 2.

[0304] As Ar 242 、Ar 243 The alkyl group is preferably an alkyl group having 1 to 12 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms. As Ar 242 、Ar 243 The aromatic hydrocarbon group 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 or a naphthyl group. As Ar 242 、Ar 243 The aromatic heterocyclic group is preferably an aromatic heterocyclic group having 3 to 30 carbon atoms, more preferably an aromatic hydrocarbon group having 5 to 24 carbon atoms, specifically preferably a carbazolyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, more preferably a dibenzofuranyl group.

[0305] Ar 241 、Ar 242 、Ar 243 The substituent that may be possessed is preferably a group selected from the aforementioned substituent group S, more preferably a hydrocarbon group included in the substituent group S, and even more preferably a hydrocarbon group among the groups preferred as the substituent group S.

[0306] The charge transporting material used together with the fluorescent material is not particularly limited, but is preferably a material represented by the following formula (212).

[0307] [Chemistry 16]

[0308] In the above formula (212), R 251 、R 252 Each independently represents a structure represented by the following formula (213), R 253 Indicates a substituent, there are multiple R 253 When n43 is an integer from 0 to 8, they may be the same or different.

[0309] [Chemistry 17]

[0310] In the above formula (213), * represents the bonding site to the anthracene ring of formula (212), Ar 254 、Ar 255 Each independently represents an aromatic hydrocarbon structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent, Ar 254 、Ar 255When a plurality of them exist, they may be the same or different, n44 is an integer of 1 to 5, and n45 is an integer of 0 to 5.

[0311] Ar 254 It is preferably a monocyclic or condensed aromatic hydrocarbon structure having 6 to 30 carbon atoms which may have a substituent, and more preferably a monocyclic or condensed aromatic hydrocarbon structure having 6 to 12 carbon atoms which may have a substituent.

[0312] Ar 255 Preferably, it is a monocyclic or condensed aromatic hydrocarbon structure having 6 to 30 carbon atoms which may have a substituent, or a condensed aromatic heterocyclic structure having 6 to 30 carbon atoms which may have a substituent. 255 More preferably, it is a monocyclic or condensed aromatic hydrocarbon structure having 6 to 12 carbon atoms which may have a substituent, or a condensed aromatic heterocyclic structure having 12 carbon atoms which may have a substituent.

[0313] n44 is preferably an integer of 1 to 3, more preferably 1 or 2. n45 is preferably an integer of 0-3, more preferably 0-2.

[0314] Substituent R 253 、Ar 254 and Ar 255 The substituent that may be present is preferably a group selected from the aforementioned substituent group S. More preferably, it is a hydrocarbon group included in the substituent group S, and even more preferably, it is a hydrocarbon group among the groups preferred as the substituent group S.

[0315] The molecular weight of the fluorescent material and the charge transporting 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. Furthermore, it is preferably 300 or more, more preferably 350 or more, and even more preferably 400 or more.

[0316] [Hole blocking layer] A hole blocking layer 6 may be provided between the light-emitting layer 5 and the electron injection layer 8 described later. The hole blocking layer 6 is a layer in the electron transport layer that further serves to block holes moving from the anode 2 from reaching the cathode 9. The hole blocking layer 6 is a layer stacked 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.

[0317] The hole blocking layer 6 has the function of blocking holes moving from the anode 2 from reaching the cathode 9 and the function of efficiently transporting electrons injected from the cathode 9 toward the light-emitting layer 5 .

[0318] Examples of the physical properties required of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and a high excited triplet energy level (T1). As materials for the hole blocking layer 6 that meet such conditions, for example, there can be mentioned: mixed ligand complexes such as bis(2-methyl-8-hydroxyquinolinolato)(phenol)aluminum, bis(2-methyl-8-hydroxyquinolinolato)(triphenylsilanol)aluminum, metal complexes such as bis(2-methyl-8-hydroxyquinolinolato)aluminum-μ-oxo-bis-(2-methyl-8-hydroxyquinolinolato)aluminum binuclear metal complexes, styryl compounds such as distyrylbiphenyl derivatives (Japanese Patent Application Publication No. 11-242996), triazole derivatives such as 3-(4-biphenyl)-4-phenyl-5(4-tert-butylphenyl)-1,2,4-triazole (Japanese Patent Application Publication No. 7-41759), and phenanthroline derivatives such as bathocuproin (Japanese Patent Application Publication No. 10-79297). Furthermore, compounds having at least one pyridine ring substituted at the 2-, 4-, or 6-positions as described in International Publication No. 2005 / 022962 are also preferred as materials for the hole-blocking layer 6 .

[0319] There is no limitation on the method for forming the hole blocking layer 6. The hole blocking layer 6 can be formed by a wet film forming method, an evaporation method, or other methods. The hole blocking layer 6 may have any thickness as long as the effects of the present invention are not significantly impaired. The hole blocking layer 6 has a thickness of usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[0320] [Electron transport layer] The electron transport layer 7 is a layer for transporting electrons and is provided between the light emitting layer 5 and the cathode 9 .

[0321] As the electron transport material of the electron transport layer 7 , a compound that has high efficiency in electron injection from the cathode 9 or an adjacent layer on the cathode 9 side and has high electron mobility and can efficiently transport injected electrons is generally used. Examples of compounds satisfying such conditions include metal complexes such as aluminum complexes or lithium complexes of 8-hydroxyquinoline (Japanese Patent Application Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, tribenzimidazolylbenzene (U.S. Patent No. 5,645,948), quinoxaline compounds (Japanese Patent Application Laid-Open No. 6-207169), phenanthroline derivatives (Japanese Patent Application Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinonediimine, triazine compound derivatives, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

[0322] As the electron transport material used in the electron transport layer 7, by doping sodium, potassium, cesium, lithium, rubidium and other alkali metals (described in Japanese Patent Laid-Open No. 10-270171, Japanese Patent Laid-Open No. 2002-100478, Japanese Patent Laid-Open No. 2002-100482, etc.) in an electron transport organic compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline, it is possible to take into account both electron injection transport and excellent film quality, and therefore it is preferred. In addition, it is also effective to dope inorganic salts such as lithium fluoride or cesium carbonate in the above-mentioned electron transport organic compound.

[0323] There is no limitation on the method for forming the electron transport layer 7. The electron transport layer 7 can be formed by a wet film forming method, an evaporation method, or other methods.

[0324] The thickness of the electron transport layer 7 is arbitrary as long as the effects of the present invention are not significantly impaired. 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.

[0325] [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 described later. The electron injection layer 8 is composed of an inorganic salt or the like.

[0326] Examples of materials for the electron injection layer 8 include lithium fluoride (LiF), magnesium fluoride (MgF2), lithium oxide (Li2O), and cesium (II) carbonate (CsCO3) (see Applied Physics Letters, 1997, Vol. 70, pp. 152; Japanese Patent Application Publication No. 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

[0327] The electron injection layer 8 often does not have charge transport properties, and therefore is preferably formed as an extremely thin film for efficient electron injection. The film thickness is usually 0.1 nm or more, and preferably 5 nm or less.

[0328] [cathode] The cathode 9 is an electrode that plays a role in injecting electrons into the layer on the light-emitting layer 5 side.

[0329] Typical materials for cathode 9 include 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; and conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline. Among these, metals with low work functions are preferred for efficient electron injection. For example, suitable metals such as tin, magnesium, indium, calcium, aluminum, and silver, or alloys thereof, are used. Specific examples include low-work-function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.

[0330] As the material of the cathode 9 , only one kind may be used, or two or more kinds may be used in combination in any combination and ratio.

[0331] The thickness of cathode 9 varies depending on the desired transparency. When transparency is required, the visible light transmittance is typically set to 60% or greater, preferably 80% or greater. In this case, the thickness of cathode 9 is typically 5 nm or greater, preferably 10 nm or greater, and typically 1000 nm or less, preferably approximately 500 nm or less. When opacity is desired, cathode 9 can have any thickness and can be the same thickness as the substrate.

[0332] Different conductive materials may be stacked on the cathode 9 . For example, if a metal cathode composed of a low-work-function metal such as an alkali metal such as sodium or cesium, or an alkaline earth metal such as barium or calcium is further laminated with a metal layer having a high work function and being stable to the atmosphere, the stability of the device is increased, which is therefore preferred. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum are used. These materials may be used alone or in any combination and ratio.

[0333] [Other layers] The organic electroluminescent element of the present invention may have other structures without departing from the scope of its main purpose. For example, between the anode 2 and the cathode 9, in addition to the layer described above, any layer may be provided, and any unnecessary layer in the layer described above may be omitted, as long as the performance is not impaired.

[0334] Furthermore, one or more other organic layers may be provided on the upper layer of the cathode 9 as a protective layer for the cathode.

[0335] In the layer structure described above, components other than the substrate may be stacked in the reverse order. Figure 3 If the layer structure is as follows, other components can be arranged on the substrate 1 in the order of cathode 9, electron injection layer 8, electron transport layer 7, hole blocking layer 6, light-emitting layer 5, hole transport layer 4, hole injection layer 3, and anode 2.

[0336] The organic electroluminescent element of the present invention may be configured as a single organic electroluminescent element, or may be applied to a structure in which a plurality of organic electroluminescent elements are arranged in an array, or may be applied to a structure in which anodes and cathodes are arranged in an XY matrix.

[0337] Each of the above-mentioned layers may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

[0338] Organic electroluminescent devices An organic electroluminescent device such as an organic EL display or organic EL lighting device can be fabricated by providing two or more organic electroluminescent elements that emit light in different colors. By providing at least one, and preferably all, of these organic electroluminescent elements as the organic electroluminescent element of the present invention, a high-quality organic electroluminescent device can be provided.

[0339] [Organic EL display device] There are no particular limitations on the type or structure of an organic EL display device using the organic electroluminescent element of the present invention, and the organic electroluminescent element of the present invention can be used and assembled according to a conventional method. For example, an organic EL display device can be formed by the method described in "Organic EL Display" (Ohmsha Co., Ltd., published on August 20, 2004, written by Shizuo Tokito, Chinaya Adachi, and Hideyuki Murata).

[0340] [Organic EL Lighting] There are no particular limitations on the style or structure of the organic EL lighting using the organic electroluminescent element of the present invention, and the organic electroluminescent element of the present invention can be used and assembled according to a conventional method. Example

[0341] The present invention will be described in more detail below with reference to the following examples. However, the present invention is not limited to the following examples, and the present invention can be implemented with any modifications without departing from the spirit of the present invention.

[0342] [Measurement of contact angle] <Preparation of Lyophobic Resist> Hereinafter, the photosensitive resin composition of the present invention will be described with reference to specific examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

[0343] Photosensitive, lyophobic resists for Examples and Comparative Examples were prepared by mixing the components in the proportions listed in Table 2 to achieve a total solids content of 19% by weight. A solvent consisting of a 7:3 mixture of propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether was used, and the components were stirred until uniform. The proportions (weight %) of the components in Table 2 refer to the solids content of each component relative to the total solids content. [Table 2] Table 2

[0344] Photopolymerization initiator a-1: a compound having the following chemical structure.

[0345] [Chemistry 18]

[0346] Alkali-soluble resin b1: ZCR-8029 (manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight Mw=6640, acid value=62 mgKOH / g) In addition, resin b1 corresponds to epoxy (meth)acrylate resin (B1). Resin b-1 has a partial structure represented by the following formula.

[0347] [Chemistry 19]

[0348] Alkali-soluble resin b-2: ZAR-1872 (manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight Mw = 8000, acid value = 80 mgKOH / g) In addition, resin b-2 corresponds to epoxy (meth)acrylate resin (B1). Resin b-2 has a partial structure represented by the following formula.

[0349] [Chemistry 20]

[0350] In the above formula, * represents a bonding site with a monovalent group represented by the following formula or a hydrogen atom.

[0351] [Chemistry 21]

[0352] Photopolymerizable compound c-1: manufactured by Kyoeisha Chemical Co., Ltd., pentaerythritol tetraacrylate. Liquid repellent d-1: acrylic copolymer resin containing a structural unit having a perfluoroalkyl group, a structural unit having an ethylenic double bond, and a structural unit having a carboxyl group. Mw: 90,000, fluorine atom content: 20% by weight. Additive e-1: manufactured by Nippon Kayaku Co., Ltd., KAYAMER PM-21. Additive f-1: methylhydroquinone represented by the following formula.

[0353] [Chemistry 22]

[0354] <Film Formation of Liquid-Repellent Resist Film> On a 0.7 mm thick glass plate, 10 nm of indium tin oxide (ITO) and 100 nm of silver palladium copper (APC) alloy were stacked by sputtering, and 10 nm of ITO was further stacked to produce a glass substrate with a reflective film. The substrate was cut into a size of 100 mm × 100 mm, and a spin coater was used on the reflective film side to coat the aforementioned liquid-repellent resist after curing in a manner such that the film thickness was 1.4 μm. The drying process was then carried out for 60 seconds using a vacuum dryer. Subsequently, the film was heated and dried on a hot plate heated to 125°C for 120 seconds. The resulting film was exposed without using a light shield. A mirror projection type exposure machine (manufactured by Canon Inc., MPA-600FA) was used with an exposure dose of 120 mJ / cm 2 Exposure was performed for 30 seconds. The illumination was 500 mW / cm 2 . Next, the film was spray-developed with a 2.38 wt% TMAH (tetramethylammonium hydroxide) aqueous solution at 24°C for 80 seconds, washed with pure water for 20 seconds, and then baked in an oven heated to 230°C for 30 minutes to form a lyophobic resist film.

[0355] <Measurement of Contact Angle> The contact angles of the functional ink and all solvents contained in the functional ink were measured on this lyophobic resist film. Contact angle measurements were performed using a contact angle meter (DM0-501, manufactured by Kyowa Interface Science Co., Ltd.) with a liquid volume of 1.0 μL. The contact angles θ4 and θ5 measured 0.1 seconds after the dropwise addition of various solvents are summarized in Tables 6 and 7.

[0356] <Peeling off of surface liquid-repellent components> The outermost surface of the lyophobic resist film was treated using a plasma surface treatment apparatus to remove the lyophobic agent present on the outermost surface, thereby forming simulated bank side surfaces on the substrate. Plasma treatment was performed using a small plasma cleaner (PDC-32G manufactured by Harrick Plasma). The plasma treatment was performed at a vacuum level of 140 to 160 Pa, with an atmospheric pressure of approximately 40 sccm, a radio frequency (RF) power of 18 W, and a treatment time of 30 seconds. Here, the film formed by removing the lyophobic agent from the surface of the lyophobic resist film is referred to as a pseudo-bank side film.

[0357] <Measurement of Contact Angle> The contact angles of various solvents were measured on the simulated bank side film. Contact angle measurements were performed using a contact angle meter (DM0-501, manufactured by Kyowa Interface Science Co., Ltd.) with a liquid volume of 1.0 μL. The contact angles θ1 measured 0.1 seconds after the dropwise addition of various solvents are summarized in Table 3.

[0358] [Table 3] Table 3

[0359] [Evaluation of Flatness of Functional Films] Next, the flatness when ink is applied and dried in the region partitioned by the bank will be described based on examples.

[0360] [Examples 1 to 6, Comparative Examples 1 to 3] <Preparation of functional ink> The polymer compound (P-1) represented by the following structural formula was weighed using an electronic balance as the hole injection material 1. Next, the low-boiling point solvent I and the high-boiling point solvent II in Table 4 were mixed at a ratio of 75:25 (volume ratio) to form a mixed solvent 1. The hole injection material 1 was mixed with the mixed solvent 1 in a screw bottle in such a manner that it accounted for 2.3% by weight of the total composition obtained. The mixture was then placed in a vacuum chamber together with the screw bottle, and vacuuming and filling with nitrogen were repeated three times to partially replace the gas in the screw bottle with nitrogen. Then, while stirring at 420 rpm using a magnetic stirrer, the mixture was heated at a hot plate temperature of 110°C for 3 hours to obtain a composition. 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 inks 1 to 3 in Table 4.

[0361] [Chemistry 23]

[0362] [Table 4] Table 4

[0363] <Substrate Preparation> An indium tin oxide (ITO) film, a silver indium compound film, and an indium tin oxide film are sequentially formed on a glass substrate with a film thickness of 0.7 mm by a sputtering method, and an electrode pattern is formed by a conventional photoetching method. A liquid-repellent resist used to simulate the side film of the partition bank is coated on the substrate with a film thickness of 0.7 μm to 2.1 μm. Then, a drying process is performed for 60 seconds using a vacuum dryer. Next, heat and dry on a hot plate heated to 125°C for 120 seconds. The obtained coating film is exposed using a light shield. A mirror projection type exposure machine (manufactured by Canon Inc., MPA-600FA) is used with an exposure amount of 140 mJ / cm 2 Exposure was performed for 35 seconds. The illumination was 500 mW / cm 2 . The size of the opening of the light shield is 242 μm in the long axis, 57 μm in the short axis and 26.5 μm in the corner R, with 61 openings arranged in the short axis direction and 31 in the long axis direction, for a total of 1891 openings. Next, it was spray developed with a 2.38 wt% TMAH (tetramethylammonium hydroxide) aqueous solution at 24°C for 80 seconds, and then washed with pure water for 20 seconds. Through these operations, the substrate with a pattern formed by removing the unnecessary parts was heated and cured at 230°C in an oven for 30 minutes to obtain the liquid-repellent barriers 1 to 5 of Table 5 having a pattern.

[0364] <Measurement of Cone Angle of Lyophobic Bank> The cross-sectional shape of the patterned portion of the patterned lyophobic resist film was observed at 10,000 times magnification using a scanning electron microscope (SEM), and the angle between the substrate and the bank was measured as a taper angle θ2.

[0365] [Table 5] Table 5 Liquid-repellent dike Cone angle θ2 (°) 1 15.7 2 31.3 3 60.3 4 67.7 5 70.8

[0366] The obtained substrate was placed in ultrapure water and ultrasonically cleaned for 5 minutes, and then dried in a clean oven preheated to 210° C. for 30 minutes.

[0367] <Application of functional ink> Functional ink 1 was filled into an inkjet printer cartridge (DMCLCP-11610, manufactured by Fujifilm Corporation) using a micropipette and applied to the openings of the substrate using an inkjet printer (DMP-2831, manufactured by Fujifilm Corporation). The inkjet printer's discharge voltage was adjusted so that each drop of functional ink ejected from the inkjet head nozzle was 10 pL, with eight drops applied to each opening. The functional ink was applied to an opening measuring 1,134 pixels (54 pixels in the short axis direction and 21 pixels in the long axis direction), followed by the following drying and baking steps.

[0368] <Drying and calcination> The obtained coating film was placed in a chamber sealed with an openable lid and dried under reduced pressure to a pressure of 0.1 Pa or less using a multistage pump (VMR-050 manufactured by Ulvac Co., Ltd.) combining a mechanical booster pump and a rotary oil pump to form a functional film.

[0369] The reduced pressure drying is performed by reducing the pressure from atmospheric pressure to 1 to 10 Pa over 240 seconds and then reducing the pressure to 0.1 Pa or less over 180 seconds, thereby volatilizing the solvent components in the functional ink and forming a functional film.

[0370] This functional film was placed on a hot plate heated to 230° C. and baked for 30 minutes to prepare a functional film 1 .

[0371] <Evaluation of functional films> The obtained functional film was measured for film thickness distribution in the short axis direction relative to the opening using a probe contact type step profiler (manufactured by Kosaka Laboratory Co., Ltd., ET-100). Figures 4-12 middle. In addition, the flatness U was calculated using the following formula (X) for the distribution of the measured film thickness, and the flatness of the functional film 1 was evaluated. The results are shown in Tables 6 and 7. Furthermore, a graph plotting the relationship between θ2-θ1 and the flatness U is shown in Figure 13 middle. Figure 13 In the figure, the relationship in the example is plotted with "●", and the relationship in the comparative example is plotted with "○". U(%)=LF / LB×100(X) Here, LB represents the length of the bank opening (unit: μm), and LF represents the length of the portion whose thickness is not more than 15 nm thicker than the average film thickness in 50% LB (unit: μm).

[0372] [Table 6]

[0373] [Table 7]

[0374] According to Table 6 and Table 7 and Figure 13 From the relationship between θ2-θ1 and flatness U shown, it can be seen that the flatness U is above 80% in the combination of functional ink and liquid-repellent dam containing the following organic solvent, wherein the difference between the contact angle θ1 with the simulated dam side substrate and the cone angle θ2 of the dam shows an angle greater than -8° and less than 45°. -8°<θ2-θ1<45°

[0375] This is considered to be because the functional ink has a moderate contact angle with the bank side surface, and thus can wet downward appropriately without self-pinning, resulting in a high flatness U.

[0376] While the present invention has been described in detail using specific embodiments, it will be apparent to one skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.

[0377] <Confirming Taper Angle θ2 and Wire Breakage Using a Vapor Deposition Element> Commercially available lyophobic bank substrates were plasma treated to produce lyophobic bank substrates having different taper angles θ2. A 100nm AlCu alloy is formed on a glass substrate with a film thickness of 0.5mm, and an anode electrode of a 13nm indium tin oxide (ITO) film is formed thereon. A 1.5μm liquid-repellent resist is formed thereon with an opening size of 180μm in the long axis, 60μm in the short axis, and 30μm in the corner R. Seven openings are arranged in the short axis direction, and 22 are arranged in the long axis direction, with a total of 154 openings arranged, to obtain substrates with different cone angles θ2 as shown in Table 8.

[0378] [Table 8] Table 8 Cone angle θ2 Reference example 1 (○) 61° Reference Example 2 (▲) 72° Reference Example 3 (×) 80°

[0379] An organic electroluminescent element was prepared by stacking in sequence by vacuum deposition a 10 nm thick molybdenum oxide hole injection layer, a 60 nm thick 9H-fluorene-2-amine-N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] (HT-211) hole transport layer, a 60 nm thick tris(8-hydroxyquinoline)aluminum (Alq3) light emitting layer, a 1 nm thick 8-hydroxyquinoline lithium (Liq) electron injection layer, a 13 nm thick cathode co-deposited with Ag:Mg=9:1, and a 30 nm thick HT-211 capping layer thereon. Next, a desiccant is applied to the recessed portion of a sealing glass having a central recess, and a UV-curable resin is applied to the frame surrounding the recessed portion. The sealing glass is positioned so that the recessed portion completely covers the organic electroluminescent element and linear pattern on the partition substrate. The sealing glass is then attached to the partition substrate, and the UV-curable resin is irradiated with UV light to cure and seal the hollow structure, thereby producing a device for evaluating the organic electroluminescent element.

[0380] <Measurement of Electrical Characteristics of Organic Electroluminescent Element> The device characteristics of the organic electroluminescent device produced as described above are summarized in Figure 14 in the chart. Figure 14 In the figure, the device characteristics of Reference Example 1 are plotted as "○", the device characteristics of Reference Example 2 are plotted as "▲", and the device characteristics of Reference Example 3 are plotted as "×". The horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ).

[0381] When using vapor-deposited cathode electrodes as thin as 13 nm, current flow becomes difficult when the taper angle θ2 is greater than 70°, and the measured current density tends to decrease (Reference Examples 2 and 3). This is believed to be because as the taper angle θ2 increases, the electrode becomes thinner at the edge of the bank, resulting in increased resistance. Therefore, when the vapor-deposited cathode electrode is 13 nm or less, the taper angle θ2 is preferably less than 70°.

[0382] While various embodiments have been described above, it goes without saying that the present invention is not limited to the examples described. Those skilled in the art will appreciate that various variations or modifications are conceivable within the scope of the claims, and these naturally fall within the technical scope of the present invention. Furthermore, the various components of the above embodiments may be arbitrarily combined without departing from the spirit of the invention.

[0383] It should be noted that this application is based on the Japanese patent application (Japanese Patent Application No. 2023-011241) filed on January 27, 2023, the contents of which are incorporated herein by reference. Industrial applicability

[0384] The production method of the present invention can improve the uniformity of the thickness of the functional film in the region surrounded by the bank, and therefore can be used as a method for producing an organic electroluminescent element.

Claims

1. A method for manufacturing an organic electroluminescent element, characterized in that: The process includes the following steps: A step of applying a liquid-repellent resist on a substrate having a conductive electrode pattern and forming a plurality of openings in microscopic regions by photolithography; a step of applying a functional ink comprising at least one functional material and at least one organic solvent to the opening by a printing method; and a step of volatilizing the organic solvent contained in the functional ink by drying under reduced pressure; The surface of the lyophobic resist film obtained by curing the lyophobic resist is peeled off by external energy to obtain a film for contact angle measurement. When the contact angle between the solvent with the highest boiling point among all organic solvents contained in the functional ink and the film for contact angle measurement is defined as θ1, and the taper angle of the bank formed by the lyophobic resist so as to surround the opening is defined as θ2, the following relationship is satisfied: -8°<θ2-θ1<45°.

2. The method for manufacturing an organic electroluminescent element according to claim 1, wherein: The functional ink comprises at least two organic solvents.

3. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The taper angle θ2 is greater than 30° and less than 70°, and the height of the bank is less than or equal to 1.9 μm.

4. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The contact angle θ1 is greater than 0° and less than 78°.

5. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The surface of the lyophobic resist film is peeled off by the external energy by UV / ozone treatment or plasma treatment.

6. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The content of the organic solvent having the contact angle θ1 is 5% by weight or more relative to the total weight of all organic solvents contained in the functional ink.

7. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The content of the organic solvent having the contact angle θ1 is less than 50 wt % relative to the total weight of all organic solvents contained in the functional ink.

8. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The boiling point of the solvent with the lowest boiling point among all the organic solvents contained in the functional ink is 200° C. or higher.

9. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The difference between the boiling point of the organic solvent having the contact angle θ1 and the boiling point of the organic solvent with the lowest boiling point among all the organic solvents contained in the functional ink is 20° C. or more.

10. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The functional material comprises at least one hole-transporting compound and at least one electron-accepting compound.

11. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The time for drying the organic solvent contained in the functional ink under reduced pressure is 1 minute or longer and less than 15 minutes.

12. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The lyophobic resist contains a resin containing fluorine atoms.

13. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The time for treating the lyophobic resist film with the external energy is 30 seconds or more and 300 seconds or less.

14. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The contact angle θ1 is greater than or equal to 10° and less than 50°.

15. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: When the contact angle between the functional ink and the surface of the liquid-repellent resist film is defined as θ4, the difference between the contact angle θ4 and the contact angle θ1 is 40° or more.

16. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The organic solvent contained in the functional ink includes two or more selected from the group consisting of benzoate-based solvents, naphthalene derivatives, diphenylmethane derivatives, aromatic ether-based solvents, benzene derivatives, aromatic ether-based solvents, and biphenyl derivatives.

17. The method for producing an organic electroluminescent element according to claim 1 or 2, wherein: The lyophobic resist contains a colorant.

18. An organic electroluminescent device produced using the production method according to claim 1 or 2.

19. An organic electroluminescent element comprising a functional film on openings of microscopic regions defined by banks formed by curing a lyophobic resist, wherein: When the contact angle between one solvent selected from the group consisting of Barrel Process oil B-03, 2-ethylhexyl benzoate, and benzyl benzoate and the surface of the upper surface of the bank after being peeled off by external energy is set to θ3, and the taper angle of the bank is set to θ2, the following relationship is satisfied for at least one of the solvents: -8°<θ2-θ3<45°.

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