Composition and method for manufacturing organic electroluminescent element

Abstract

A composition containing a functional material, a first solvent and a second solvent, the first solvent being a water-insoluble aromatic solvent, the boiling point of the first solvent being higher than the boiling point of the second solvent, the difference between the boiling points of the first solvent and the second solvent being 10 DEG C or more, the flow activation energy of the first solvent being 22 kJ / mol to 35 kJ / mol, and the flow activation energy of the second solvent being 30 kJ / mol to 35 kJ / mol. The content ratio of the first solvent is 5-50 wt% relative to the total amount of the first solvent and the second solvent, and the boiling point of the second solvent is 245 DEG C or higher.

Description

[0001] This application is a divisional application of the Chinese patent application with the application number 201980029200.0 (the invention name of the original application is "Composition and Manufacturing Method of Organic Electroluminescent Element", and the application date of the original application is April 24, 2019). Technical Field

[0002] The present invention relates to a composition suitable for forming an organic film composed of a functional material, that is, a functional film, in the manufacture of an organic electroluminescent element, and a method for manufacturing an organic electroluminescent element using the composition. Background Art

[0003] As a method for manufacturing an organic electroluminescent element, there is generally a manufacturing method in which an organic material is formed into a film and laminated by a vacuum evaporation method. In recent years, as a manufacturing method with more excellent material use efficiency, research on a wet film-forming manufacturing method in which a solutionized organic material is formed into a film and laminated by an inkjet method or the like has become popular.

[0004] In the manufacture of an organic electroluminescent element using wet film formation, particularly an organic EL display, a method has been studied in which each pixel is partitioned by a partition wall called a bank, and an ink of a composition for forming an organic film constituting the organic electroluminescent element is ejected into a minute region within the bank by an inkjet method to form a film. At this time, a technique has been proposed in which various surface modifiers are mixed in the ink to obtain a flatter film within the region surrounded by the bank (Patent Documents 1 and 2).

[0005] However, in the conventional method, the flatness of the film within the region surrounded by the bank is insufficient.

[0006] In Patent Document 3, 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 is disclosed.

[0007] Patent Document 1: WO 2010 / 104183

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2002-056980

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-185640

[0010] In the case of coating using an inkjet device, inks with too high a viscosity have problems in ejection performance, and inks with too low a viscosity cannot be retained in the nozzle. Therefore, there is an appropriate viscosity range to a certain extent. On the other hand, during the drying process of the liquid film, due to various flows such as liquid movement caused by a concentration gradient or Marangoni convection, there is a tendency for the shape of the dried film to become complicated. In order to control this complex film shape, by increasing the viscosity of the ink to a certain extent, the flow rate is slowed down, making it easier to control. However, due to the formation of a high viscosity, it may exceed the viscosity range within which the ink for inkjet can be appropriately ejected, making it difficult to adjust the viscosity within an appropriate range. In particular, when the solute dissolved in the ejected ink is mainly a low-molecular material, since the viscosity of the ink is at the same level as that of the solvent, even if the solvent volatilizes to a certain extent, the viscosity of the ink does not change significantly, and it is easy to have a problem that the dried film is difficult to become flat due to the flow of the liquid.

[0011] Even in the case of using a plurality of solvents having different boiling points as in Patent Document 3, there is still room for improvement in the flatness of the end portion of the panel coated with the ink. SUMMARY OF THE INVENTION

[0012] An object of the present invention is to provide a composition and a method for manufacturing an organic electroluminescent element using the composition. When the organic film constituting the organic electroluminescent element is formed by wet film formation using the composition, the uniformity of the film thickness in the region surrounded by the dam can be improved, and furthermore, good flatness can be achieved not only in the central portion of the panel coated with the ink but also at the end portions.

[0013] The present inventors have found that when an organic film constituting an organic electroluminescent element is formed in the region surrounded by a dam by wet film formation, by using a solvent having a high temperature dependence (flow activation energy) of viscosity as a high-boiling-point solvent in a mixed solution containing two or more solvents having different boiling points and a composition with a functional material, good film thickness uniformity can be achieved when wet film formation of the organic film is performed in the region surrounded by the dam. In addition, it has been found that by setting the boiling point of the low-boiling-point solvent to 245 °C or higher, flatness can be improved not only in the central portion of the panel but also at the end portions.

[0014] That is, the present invention has the following configuration.

[0015] [1]A composition comprising a functional material, a first solvent, and a second solvent, wherein the first solvent is a water-insoluble aromatic solvent, the boiling point of the first solvent is higher than that of the second solvent, the difference in boiling points between the first solvent and the second solvent is 10 °C or more, the flow activation energy of the first solvent is 22 kJ / mol or more and 35 kJ / mol or less, the content ratio of the first solvent relative to the total amount of the first solvent and the second solvent is 5 to 50% by weight, and the boiling point of the second solvent is 245 °C or more.

[0016] [2]The composition according to [1], wherein the total content of the first solvent and the second solvent in the composition is 50% by weight or more.

[0017] [3]The composition according to [1] or [2], wherein the molecular weight of the functional material is 50,000 or less.

[0018] [4]The composition according to any one of [1] to [3], wherein the viscosity of the second solvent at 23 °C is 5 mPas or less.

[0019] [5]The composition according to any one of [1] to [4], wherein the difference in boiling points between the first solvent and the second solvent is 30 °C or more.

[0020] [6]The composition according to any one of [1] to [5], wherein the flow activation energy of the first solvent is 5 kJ / mol or more greater than that of the second solvent.

[0021] [7]The composition according to any one of [1] to [6], wherein the surface tension of the first solvent is 30 mN / m or more.

[0022] [8]The composition according to any one of [1] to [7], wherein the first solvent and the second solvent are each any one of naphthalene, benzoate, and aromatic ether which may have substituents.

[0023] [9]The composition according to any one of [1] to [7], wherein the first solvent is any one of 2-ethylhexyl benzoate, benzyl benzoate, acetylnaphthalene, dimethyl phthalate, diethyl phthalate, ethylbiphenyl, isopropylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, and 2-phenoxyethyl isobutyrate, and the second solvent is any one of methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, methoxynaphthalene, butyl benzoate, pentyl benzoate, isopentyl benzoate, diphenylmethane, and benzyltoluene.

[0024]

[10] A method for manufacturing an organic electroluminescent element, comprising a step of wet film formation using the composition according to any one of [1] to [9].

[0025] With the composition of the present invention, it is possible to achieve good uniformity in the film thickness of the functional film within the region surrounded by the dam. In addition, the flatness can be improved not only at the central part of the panel coated with the ink but also at the ends. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic cross-sectional view showing a structural example of the organic electroluminescent element of the present invention.

[0027] Figure 2 It is a graph showing the distribution of the light-emitting layer and the blank in Reference Example 1.

[0028] Figure 3 It is a graph showing the distribution of the light-emitting layer and the blank in Reference Example 2.

[0029] Figure 4 It is a graph showing the distribution of the light-emitting layer and the blank in Comparative Example 1.

[0030] Figure 5 It is a graph showing the distribution of the light-emitting layer and the blank in Comparative Example 2.

[0031] Figure 6 It is a graph showing the distribution of the light-emitting layer and the blank in Comparative Example 3.

[0032] Figure 7 It is a graph showing the distribution of the flatness evaluation of Measurement Site 1 in Example 1.

[0033] Figure 8 It is a graph showing the distribution of the flatness evaluation of Measurement Site 2 in Example 1.

[0034] Figure 9 It is a graph showing the distribution of the flatness evaluation of Measurement Site 1 in Example 2.

[0035] Figure 10 It is a graph showing the distribution of the flatness evaluation of Measurement Site 2 in Example 2.

[0036] Figure 11 It is a graph showing the distribution of the flatness evaluation of Measurement Site 1 in Example 3.

[0037] Figure 12 It is a graph showing the distribution of the flatness evaluation of Measurement Site 1 in Comparative Example 4.

[0038] Figure 13 It is a graph showing the distribution of the flatness evaluation of Measurement Site 2 in Comparative Example 4.

[0039] Figure 14 It is a graph showing the distribution of the flatness evaluation of measurement site 1 of Comparative Example 5.

[0040] Figure 15 It is a graph showing the distribution of the flatness evaluation of measurement site 2 of Comparative Example 5.

[0041] Figure 16 It is a graph showing the distribution of the flatness evaluation of measurement site 1 of Comparative Example 6.

[0042] Figure 17 It is a graph showing the distribution of the flatness evaluation of measurement site 2 of Comparative Example 6. Detailed Description

[0043] [Composition]

[0044] The composition of the present invention is characterized in that it contains a functional material, a first solvent, and a second solvent. The first solvent is a water-insoluble aromatic solvent, the boiling point of the first solvent is higher than that of the second solvent, the difference in boiling points between the first solvent and the second solvent is 10 °C or more, the flow activation energy of the first solvent is 22 kJ / mol or more and 35 kJ / mol or less, the content ratio of the first solvent is 5 to 50% by weight relative to the total amount of the first solvent and the second solvent, and the boiling point of the second solvent is 245 °C or more.

[0045] In the composition of the present invention, the solvents contained therein can be used as inks that can be ejected from a micro nozzle because the boiling point of the second solvent is 245 °C or more and the boiling point of the first solvent is higher than that of the second solvent, that is, the boiling points of the two solvents are 245 °C or more. The composition of the present invention shows a moderately low viscosity at room temperature, but if the temperature decreases due to the heat of vaporization during the vacuum drying process, a sharp increase in viscosity will occur. As a result, the flow rate of the liquid slows down, the film shape can be controlled, and a flat film can be obtained. This effect is more significant in a composition in which the solute, which is less likely to increase in viscosity even when the solid component concentration of the liquid increases due to solvent evaporation, is a low molecule. In addition, since the boiling point of the second solvent with a low boiling point is also 245 °C or more, solvent vaporization can be prevented even at the end of the panel where drying is particularly fast before the vacuum drying process. Therefore, the temperature can be sufficiently reduced during the vacuum drying process, and a flat film can be obtained.

[0046] 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 is sometimes simply referred to as ink.

[0047] 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 and coated within the region surrounded by the dam, the ink within the region surrounded by the dam is sometimes referred to as a liquid or a liquid film, and the ink ejected from the nozzle is sometimes referred to as a droplet.

[0048] Sometimes, the ink that dries the liquid film in the area surrounded by the partition dike and whose solvent composition ratio of the liquid film changes due to solvent volatilization is also called a liquid or a liquid film.

[0049] The film containing a functional material obtained by coating and forming the composition of the present invention and volatilizing and drying an organic solvent is called a functional film. In addition, a film containing an organic compound and not containing a solvent or substantially obtained by volatilizing and drying a solvent is called an organic film. The functional film is a kind of organic film.

[0050] [Solvent]

[0051] <Type of Solvent>

[0052] In the present invention, from the viewpoints of improving flatness due to a decrease in temperature and a sharp increase in viscosity and ensuring flatness at the panel end, solvents with a boiling point of 245 °C or higher are used as both the first solvent and the second solvent.

[0053] The solvent with a boiling point of 245 °C or higher is not particularly limited, and preferably, non-water-soluble aromatic solvents such as aromatic hydrocarbon solvents, aromatic ester solvents, aromatic ether solvents, and aromatic ketone solvents can be mentioned.

[0054] As the aromatic hydrocarbon solvent, benzene derivatives, naphthalene derivatives, tetrahydronaphthalene derivatives, and biphenyl derivatives are preferred.

[0055] As the benzene derivative, a benzene derivative having a total carbon atom number of the substituents of 5 or more and 12 or less and having a linear, branched, or alicyclic alkyl group as a substituent is preferred, and n-octylbenzene, n-nonylbenzene, n-decylbenzene, and dodecylbenzene can be mentioned.

[0056] As the naphthalene derivative, it is not particularly limited, and a naphthalene derivative substituted with an alkyl group is preferred, and 1-methylnaphthalene, 2-ethylnaphthalene, 2-isopropylnaphthalene, 2,6-dimethylnaphthalene, and 1-methoxynaphthalene can be mentioned.

[0057] As the tetrahydronaphthalene derivative, for example, tetrahydronaphthalene, 1,2-dihydronaphthalene, 1,4-dihydronaphthalene, etc. can be mentioned, and they may also be substituted with an alkyl group having 1 to 6 carbon atoms.

[0058] As the biphenyl derivative, it is not particularly limited, and a biphenyl derivative substituted with an alkyl group having 1 to 6 carbon atoms is preferred, and for example, 3-ethylbiphenyl, 4-isopropylbiphenyl, etc. can be mentioned.

[0059] As other preferred aromatic hydrocarbon solvents, diphenylmethane and methyldiphenylmethane can be mentioned.

[0060] As the aromatic ester solvent, benzoate solvents, phenylacetate solvents, and phthalate solvents can be mentioned.

[0061] Benzoate solvents are compounds having a benzoic acid and an ester bond, and compounds formed by ester-bonding benzoic acid which may have substituents with an alcohol having 2 or more and 12 or less carbon atoms can be used. The substituents that can be present are preferably linear or branched alkyl groups having 1 or more and 6 or less carbon atoms, or linear or branched alkoxy groups having 1 or more and 6 or less carbon atoms. A plurality of these substituents may be present, and in the case of a plurality, the total number of carbon atoms as substituents is preferably 6 or less. Examples of benzoate solvents include butyl benzoate, n-pentyl benzoate, iso-pentyl benzoate, n-hexyl benzoate, 2-ethylhexyl benzoate, benzyl benzoate, ethyl 4-methoxybenzoate, and the like.

[0062] Examples of phenylacetate solvents include ethyl phenylacetate.

[0063] Examples of phthalate solvents include dimethyl phthalate, diethyl phthalate, and dibutyl phthalate.

[0064] Examples of other preferred aromatic ester solvents include 2-phenoxyethyl acetate, 2-phenoxyethyl isobutyrate, and the like.

[0065] Aromatic ether solvents are compounds having an aromatic ring and an ether bond, and examples of aromatic ether solvents are as described below.

[0066] Examples of diphenyl ether derivatives that can be substituted with a linear or branched alkyl group having 1 or more and 6 or less carbon atoms include diphenyl ether, 2-phenoxytoluene, 3-phenoxytoluene, and 4-phenoxytoluene;

[0067] Examples of benzene derivatives having two ether bonds with a linear or branched alkyl group having 1 or more and 6 or less carbon atoms include 1,4-diethoxybenzene and 1-ethoxy-4-hexyloxybenzene;

[0068] Examples of benzene derivatives having one ether bond with a linear or branched alkyl group having 4 or more and 12 or less carbon atoms include phenyl hexyl ether;

[0069] Examples of benzyl ether solvents include dibenzyl ether;

[0070] Examples of other aromatic ether solvents include 2-phenoxyethanol.

[0071] Aromatic ketone solvents are compounds having an aromatic ring and a ketone structure, and examples include 1-acetylnaphthalene and the like.

[0072] The solvent used in the present invention can be a water-insoluble non-aromatic solvent having a boiling point of 245 °C or higher. Examples of water-insoluble non-aromatic solvents include ether solvents, glycol ester solvents, and the like.

[0073] Among them, a water-insoluble aromatic solvent is used as the first solvent.

[0074] <Boiling point>

[0075] The first solvent is a water-insoluble aromatic solvent having a boiling point 10°C or more higher than that of a second solvent with a boiling point of 245°C or more, and a flow activation energy of 22 kJ / mol or more and 35 kJ / mol or less.

[0076] Among the solvents contained in the composition of the present invention, all solvents that are water-insoluble aromatic solvents with a boiling point of 245°C or more and a flow activation energy of 22 kJ / mol or more and 35 kJ / mol or less are solvents equivalent to the first solvent, and the first solvent is all solvents equivalent to the first solvent.

[0077] The boiling points of the first solvent and the second solvent used in the present invention are both 245°C or more, and furthermore, the boiling point of the first solvent is 10°C or more higher than that of the second solvent. Therefore, during the drying process after coating, generally, the second solvent with a lower boiling point volatilizes earlier than the first solvent. As described later, when a liquid film is formed from the composition ejected into the dike and the liquid film is dried by vacuum drying or the like, the second solvent with a lower boiling point volatilizes first. At this time, the temperature of the liquid film decreases due to the heat of vaporization being taken away. At this time, if the flow activation energy of the first solvent remaining in the liquid film is within the above range, the viscosity rises sharply, the flow rate of the liquid slows down, the film shape can be controlled, and a flat film can be obtained.

[0078] Among the solvents contained in the composition of the present invention, all solvents that satisfy all of the following three conditions: (a) having a boiling point of 245°C or more, (b) being a solvent other than the solvent equivalent to the first solvent, and (c) having a boiling point lower than that of all solvents equivalent to the first solvent are solvents equivalent to the second solvent, and the second solvent is all solvents equivalent to the second solvent.

[0079] When the composition of the present invention contains a plurality of solvents equivalent to the first solvent, all of these plurality of solvents equivalent to the first solvent are the first solvent, and the boiling point of the first solvent is the weighted average boiling point of all solvents equivalent to the first solvent. Similarly, when the composition of the present invention contains a plurality of solvents equivalent to the second solvent, all of these plurality of solvents equivalent to the second solvent are the second solvent, and the boiling point of the second solvent is the weighted average boiling point of all solvents equivalent to the second solvent.

[0080] The weighted average boiling point is the sum of the values obtained by multiplying the boiling point of each solvent by the weight mixing ratio of that solvent. In the present invention, unless otherwise specified, the boiling point of the first solvent is the weighted average boiling point of all solvents equivalent to the first solvent, and the boiling point of the second solvent is the weighted average boiling point of all solvents equivalent to the second solvent.

[0081] The difference in boiling points between the first solvent and the second solvent is 10 °C or more, preferably 15 °C or more, more preferably 20 °C or more. If it is 25 °C or more, there is a more significant tendency for the second solvent to evaporate before the first solvent. Therefore, it is further preferred, more preferably 30 °C or more, and particularly preferably 35 °C or more. If the boiling point difference is above this value, it is easy to adjust the drying conditions, especially the vacuum drying conditions, in such a way that the second solvent evaporates in large quantities first and then the first solvent evaporates during the drying process, so it is preferred.

[0082] Further preferably, in addition to the above boiling point difference, when there are multiple solvents equivalent to the first solvent, the difference in boiling points between the solvent with the highest weight ratio and the solvent with the highest weight ratio when there are multiple solvents equivalent to the second solvent is also 10 °C or more, preferably 15 °C or more, more preferably 20 °C or more. If it is 25 °C or more, there is a more significant tendency for the second solvent to evaporate before the first solvent, so it is further preferred, more preferably 30 °C or more, and particularly preferably 35 °C or more. The drying process tends to reflect the volatility of the solvent with the highest weight ratio. Therefore, the boiling point difference of the solvent with the highest weight ratio is preferably above the above value.

[0083] From the perspective of facilitating the evaporation of the solvent through the drying process, especially through vacuum drying, the boiling point of the first solvent is preferably 400 °C or less, and the boiling point of the second solvent is preferably 370 °C or less. Therefore, the upper limit of the boiling point difference between the first solvent and the second solvent is 155 °C.

[0084] The second solvent can be a water-insoluble aromatic solvent with a boiling point of 245 °C or more, or a water-insoluble non-aromatic solvent with a boiling point of 245 °C or more. The second solvent is particularly preferably a water-insoluble aromatic solvent with a boiling point of 245 °C or more. By having a boiling point of 245 °C or more, even at the ends of the panel where drying is fast, solvent gasification can be prevented before the vacuum drying process. Therefore, the temperature can be sufficiently reduced during the vacuum drying process, and a flat film can be obtained even at the ends of the panel. The boiling point of the second solvent is preferably 250 °C or more, more preferably 255 °C or more, and most preferably 260 °C or more. The second solvent is preferably evaporated before the first solvent during the drying process. Therefore, the boiling point of the second solvent is preferably 320 °C or less, more preferably 300 °C or less, and particularly preferably 280 °C or less.

[0085] Among the solvents equivalent to the first solvent contained in the first solvent, the number of solvents that account for more than half of the first solvent, that is, 80% by weight or more of the first solvent, is preferably 5 or less, further preferably 3 or less, and particularly preferably 2 or less. By having the number of the first solvent within this range, it is easy to manage the composition. In addition, it is considered that it is easy to control the drying process of the first solvent and easy to obtain a flat film.

[0086] Among the solvents equivalent to the second solvent contained in the second solvent, the number of solvents that account for the majority of the second solvent, that is, 80% by weight or more of the second solvent, is preferably 5 or less, more preferably 3 or less, particularly preferably 2 or less, and most preferably 1 or less. By setting the amount of the second solvent within this range, it is easy to manage the composition. In addition, it is considered that by setting the amount of the second solvent within this range, it is easy to control the initial process of the drying process, it is easy to volatilize most of the second solvent at the initial stage of drying, and it is easy to control the temperature drop caused by the heat of vaporization and the increase in the viscosity of the first solvent.

[0087] It should be noted that in the present invention, the boiling point of the solvent is the value measured under atmospheric pressure.

[0088] <Flow activation energy>

[0089] The flow activation energy is E in the following formula (I). The flow activation energy is obtained by measuring the viscosity of the solvent while changing the temperature, plotting the logarithm of the viscosity against the reciprocal of the temperature, and determining the slope therefrom.

[0090] η = Ae x p(E / RT) (Ⅰ)

[0091] η: Viscosity (cP)

[0092] A: Constant

[0093] E: Flow activation energy (kJ / mol)

[0094] R: Gas constant (8.314 J / K / mol)

[0095] T: Temperature (K)

[0096] The flow activation energy of the first solvent is 22 kJ / mol or more and 35 kJ / mol or less. The lower limit of the flow activation energy of the first solvent is preferably 23 kJ / mol or more, more preferably 24 kJ / mol or more. The upper limit of the flow activation energy of the first solvent is preferably 34 kJ / mol or less, more preferably 32 kJ / mol or less, and further preferably 30 kJ / mol or less.

[0097] If the flow activation energy of the first solvent is above the above lower limit value, the increase in viscosity when the temperature decreases occurs moderately rapidly, and it is easy to control the flatness of the functional film. If the flow activation energy of the first solvent is below the above upper limit value, the rate of increase in viscosity when the temperature decreases is not too fast and the final viscosity is not too high, making it easy to control the flatness of the functional film, so it is preferred.

[0098] The flow activation energy of the first solvent is preferably 5 kJ / mol or more greater than that of the second solvent. In other words, the flow activation energy of the second solvent is preferably 5 kJ / mol or more lower than that of the first solvent. By setting it within this range, the action of the flow activation energy of the first solvent and the second solvent is clarified, and the design becomes easier.

[0099] When the composition is coated in the dam and dried to form a film, when the liquid amount in the dam is relatively large and the liquid amount gradually decreases while the solvent volatilizes, even if the liquid temperature decreases due to the heat of vaporization being taken away, the second solvent with a low flow activation energy is present to some extent, so it is not easily thickened and the fluidity of the liquid is maintained. During a drying process such as vacuum drying, when the liquid level drops while the solvent volatilizes in the dam, if the fluidity of the liquid is maintained, then as the liquid level drops, the liquid on the side of the dam also wets and drops, and the liquid is not easily left on the side of the dam. As a result, it is considered that it is easy to make the film thickness uniform at the edge of the dam. On the contrary, if the difference in the flow activation energy between the first solvent and the second solvent is small, sometimes even if the second solvent remains to some extent, they are respectively cooled due to the heat of vaporization and thickened. In the present invention, it is preferable that the increase in viscosity is within an appropriate range. Therefore, by making one solvent a solvent that is not easily thickened and the other solvent a solvent that is easily thickened, the most suitable thickening state can be easily selected according to the film thickness, material, drying distribution, etc. Therefore, it is preferable to set a difference in the flow activation energy between the first solvent and the second solvent as described above.

[0100] From the viewpoint that the composition maintains fluidity and easily wets and drops the side of the dam in the initial stage of drying, the difference in the flow activation energy between the first solvent and the second solvent is particularly preferably 5.2 kJ / mol or more, especially preferably 5.5 kJ / mol or more, preferably 21.0 kJ / mol or less, and particularly preferably 20.0 kJ / mol or less.

[0101] Examples of non-water-soluble aromatic solvents suitable as the first solvent having a flow activation energy of 22 kJ / mol or more and 35 kJ / mol or less include 2-ethylhexyl benzoate (23.4 kJ / mol), benzyl benzoate (24.5 kJ / mol), diethyl phthalate (27.5 kJ / mol), 2-phenoxyethyl acetate (28.6 kJ / mol), isopropyl biphenyl (24.0 kJ / mol), and the like.

[0102] In addition, examples of the second solvent having a flow activation energy 5 kJ / mol or more lower than that of such a first solvent include dibenzyl ether (18.7 kJ / mol), 3-phenoxytoluene (20.1 kJ / mol), diphenyl ether (18.3 kJ / mol), and the like.

[0103] <Viscosity>

[0104] The second solvent preferably has a viscosity of 5 mPas or less at 23°C. By having the viscosity of the second solvent below the above upper limit, when preparing the composition, a first solvent with a slightly higher viscosity or a functional material that easily increases the viscosity can also be selected, expanding the selection width of the first solvent or the functional material and the selection width of the ink concentration.

[0105] The viscosity of the second solvent is particularly preferably 4.5 mPas or less. On the other hand, from the viewpoint of easily maintaining the ink in the nozzle when filled into the inkjet head, the viscosity of the second solvent is preferably 1.0 mPas or more.

[0106] In the present invention, the viscosity of the solvent can be measured using an E-type viscometer RE85L (manufactured by Toki Sangyo) at 23°C with a cone plate rotation speed of 20 rpm to 100 rpm.

[0107] The viscosity of the first solvent is preferably 3 mPas or more and 20 mPas or less.

[0108] <Surface tension>

[0109] The surface tension of the first solvent is preferably 30 mN / m or more and preferably 45 mN / m or less. It is considered that by having the surface tension of the first solvent within this range, the surface tension of the ink as a whole is maintained within an appropriate range, enabling stable ejection using an inkjet device. In addition, it is considered that by having the surface tension of the first solvent within this range, the liquid surface in the dam is easily flattened, which is thus preferred. By having the surface tension of the first solvent above the above lower limit value, a certain amount of tension is generated on the liquid surface during drying, and the surface area tends to become smaller, so wrinkles and the like are not easily generated on the film. On the other hand, by having the surface tension of the first solvent below the above upper limit value, a surface tension difference is not easily generated during drying, and useless Marangoni convection and the like are not easily generated, so a flat film is easily formed, which is thus preferred.

[0110] In the present invention, the surface tension of the solvent can be measured by the Plate Method using a platinum plate at 23.0°C.

[0111] <Combination of solvents>

[0112] The first solvent and the second solvent contained in the composition of the present invention can each be one type or multiple types.

[0113] In particular, by including two or more types of the first solvent, the surface tension that easily generates solvent convection can be adjusted, so the flatness can be further improved, which is thus preferred.

[0114] Both the first solvent and the second solvent contained in the composition of the present invention are preferably water-insoluble solvents, and both the first solvent and the second solvent are further preferably water-insoluble aromatic solvents.

[0115] Particularly, from the viewpoint that the functional material dissolves well and is not likely to precipitate even in the drying process, the first solvent and the second solvent are each preferably any one of naphthalene, benzoate, and aromatic ether that may have substituents.

[0116] In addition, among the above solvents, as preferred combinations of the first solvent and the second solvent, the following combinations can be cited.

[0117] First solvent: It is preferably at least any one of 2-ethylhexyl benzoate, benzyl benzoate, 1-acetylnaphthalene, dimethyl phthalate, diethyl phthalate, ethylbiphenyl, isopropylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, and 2-phenoxyethyl isobutyrate, and more preferably 1 or more than 2 of 2-ethylhexyl benzoate, benzyl benzoate, 1-acetylnaphthalene, dimethyl phthalate, and 2-phenoxyethyl isobutyrate.

[0118] Second solvent: It is preferably any one of methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, methoxynaphthalene, butyl benzoate, pentyl benzoate, isopentyl benzoate, diphenylmethane, and benzyltoluene, and more preferably 1 or more than 2 of methylnaphthalene, ethylnaphthalene, and butyl benzoate.

[0119] Furthermore, as preferred combinations of the first solvent and the second solvent, mainly combinations of 2-ethylhexyl benzoate and methylnaphthalene, 2-ethylhexyl benzoate and ethylnaphthalene, 2-ethylhexyl benzoate and isopropylnaphthalene, 2-ethylhexyl benzoate and butyl benzoate, 2-ethylhexyl benzoate and isopentyl benzoate, benzyl benzoate and methylnaphthalene, benzyl benzoate and ethylnaphthalene, benzyl benzoate and isopropylnaphthalene, benzyl benzoate and butyl benzoate, and benzyl benzoate and isopentyl benzoate can be cited.

[0120] When the composition of the present invention contains 2 or more kinds of the first solvents, as preferred combinations thereof, for example, combinations of 2-ethylhexyl benzoate and benzyl benzoate, 2-ethylhexyl benzoate and dimethyl phthalate, 2-ethylhexyl benzoate and 1-acetylnaphthalene, etc. can be cited.

[0121] [Content of the first solvent and the second solvent]

[0122] Relative to the total amount of the solvents in the composition of the present invention, the content of the first solvent is 5 to 50% by weight. In order to effectively reduce the temperature of the first solvent by the volatilization of the second solvent, it is necessary to increase the volatile components. Therefore, the content of the first solvent is 50% by weight or less, preferably 40% by weight or less, and more preferably 30% by weight or less. In order to keep the functional material in a dissolved state when the second solvent volatilizes, the content of the first solvent is 5% by weight or more, preferably 10% by weight or more, and more preferably 15% by weight or more.

[0123] The total content of the first solvent and the second solvent relative to the total amount of the solvents contained in the composition is preferably 50% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, particularly preferably 85% by weight or more, especially preferably 90% by weight or more, and most preferably 95% by weight or more, with the upper limit being 100% by weight. By having the total content of the first solvent and the second solvent be at least the above lower limit, it can be used as an ink that can be ejected from a fine nozzle, the drying of the solvent can be easily controlled, and the effects of the present invention can be easily obtained.

[0124] <Other solvents>

[0125] The composition of the present invention may also contain solvents other than the first solvent and the second solvent.

[0126] As solvents other than the first solvent and the second solvent, one or more solvents having a boiling point less than 245 °C can be used, such as dibenzyl ether or benzyltoluene which have a low flow activation energy as high-boiling components.

[0127] By including these other solvents, there is an advantage that the thickening effect accompanying a decrease in temperature can be adjusted by the material. However, in order to reliably obtain the effects of the present invention brought about by including the first solvent and the second solvent, the content of the other solvents other than the first solvent and the second solvent is preferably 50% by weight or less, more preferably 30% by weight or less, further preferably 20% by weight or less, particularly preferably 15% by weight or less, especially preferably 10% by weight or less, and most preferably 5% by weight or less relative to the total solvents contained in the composition of the present invention.

[0128] [Functional materials]

[0129] The functional material in the present invention preferably has a molecular weight of 50,000 or less. The functional material in the present invention can be a low-molecular material or a high-molecular material. In the case of a low-molecular material, more remarkable effects can be obtained. Here, the low-molecular material preferably has a molecular weight of 10,000 or less, and more preferably a molecular weight of 5,000 or less.

[0130] As the functional material in the present invention, the materials for the light-emitting layer, hole-injecting layer, hole-transporting layer, or electron-transporting layer described later can be used. It is preferably a material for the light-emitting layer, hole-injecting layer, or hole-transporting layer, and particularly preferably a low-molecular material for the light-emitting layer.

[0131] The composition of the present invention may contain only one kind of functional material or may contain two or more kinds.

[0132] [Content of solvent and functional material]

[0133] The content of the functional material in the composition of the present invention is not particularly limited, preferably 0.1% by weight or more, more preferably 0.5% by weight or more, still more preferably 1.0% by weight or more, preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 10% by weight or less.

[0134] As the composition of the present invention, specifically, there may be mentioned the composition for forming a light-emitting layer, the composition for forming a hole injection layer, the composition for forming a hole transport layer, and the composition for forming an electron transport layer described later. The preferred content of the solvent in each layer-forming composition is as described later. In addition, regarding the content of the functional material, the content of the material for the light-emitting layer, the material for the hole injection layer, the material for the hole transport layer, and the material for the electron transport layer described later in each layer-forming composition also conforms.

[0135] [Film formation by wet film formation method]

[0136] The composition of the present invention is applicable to the formation of a functional film in the manufacture of an organic electroluminescent element. The structure of the organic electroluminescent element is as described later.

[0137] The organic electroluminescent element in the present invention generally has minute regions formed by partitioning light-emitting pixels with a partition wall called a dam on a substrate provided with electrodes. By ejecting the composition of the present invention into the minute regions partitioned by the above-mentioned dam, drying and appropriately heating are carried out to form a functional film.

[0138] The ejection method is a method of ejecting droplets smaller than the minute regions partitioned by the dam from a minute nozzle, and preferably, the minute regions partitioned by the dam are filled with the composition of the present invention by ejecting a plurality of droplets. As the ejection method, an inkjet method is preferred.

[0139] In the wet film-forming method, after filling the minute regions partitioned by the dams with the composition of the present invention, vacuum drying is carried out. In the vacuum drying, the solvent is volatilized by reducing the pressure. In the present invention, since the boiling point of the first solvent is higher than that of the second solvent, generally, the vapor pressure of the second solvent is high, and the second solvent volatilizes prior to the first solvent. If the second solvent volatilizes, the heat of vaporization is taken away, and the temperature of the composition in the dam gradually decreases. The second solvent preferably has a small increase in viscosity due to the temperature decrease. Therefore, as described above, the flow activation energy of the second solvent is preferably lower than that of the first solvent. Thus, during the period when a certain amount of the second solvent remains, the viscosity does not increase much, but if most of the second solvent volatilizes, the temperature of the composition further decreases, and due to the first solvent having a high flow activation energy remaining in the composition, the viscosity of the composition sharply increases, and the liquid becomes less likely to flow. Therefore, in the composition within the minute regions partitioned by the dams, liquid movement caused by a concentration gradient or Marangoni convection, etc. is less likely to occur. Thereby, it is possible to suppress the disorder of the liquid surface shape caused by the flow of the composition during the solvent volatilization process, and it is possible to control the drying conditions in such a manner that the surface of the dried film after the solvent volatilization becomes uniform.

[0140] Both the first solvent and the second solvent can be mostly volatilized by vacuum drying, but in order to volatilize them sufficiently, heat drying is then carried out. The heating temperature is preferably a temperature and time at which the functional film does not crystallize or aggregate.

[0141] When the functional material is a low-molecular material, the heating temperature is generally 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, still more preferably 120°C or higher, generally 200°C or lower, preferably 180°C or lower, more preferably 150°C or lower. The heating time is generally 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer, generally 120 minutes or shorter, preferably 90 minutes or shorter, more preferably 60 minutes or shorter.

[0142] When the functional material is a high-molecular material, the heating temperature is generally 80°C or higher, preferably 100°C or higher, more preferably 150°C or higher, still more preferably 200°C or higher, generally 300°C or lower, preferably 270°C or lower, more preferably 240°C or lower. The heating time is generally 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer, generally 120 minutes or shorter, preferably 90 minutes or shorter, more preferably 60 minutes or shorter.

[0143] The heating method is maliciously implemented by means of a heating plate, an oven, infrared irradiation, etc. For infrared irradiation that directly imparts molecular vibration, the heating time is sufficient to be close to the above lower limit. In the case of heating with a heating plate where the substrate is in direct contact with the heat source or the heat source is disposed extremely close to the substrate, a longer time than infrared irradiation is required. In the case of oven heating, that is, in the case of heating using the gas inside the oven, usually air or an inert gas such as nitrogen or argon, since it takes time for the temperature to rise, a heating time close to the above upper limit of the heating time is preferred. The heating time can be appropriately adjusted according to the heating method.

[0144] [Functional film]

[0145] The functional material contained in the functional film is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, and most preferably substantially 100% by weight, with the upper limit being 100% by weight. Substantially 100% by weight means that a trace amount of additives, residual solvents, and impurities may be contained in the functional film. By the content of the functional material in the functional film being within this range, the function of the functional material can be more effectively exhibited.

[0146] [Layer constitution and formation method of organic electroluminescent element]

[0147] Refer to Figure 1 Preferred examples of the embodiments of the layer constitution and its formation method of an organic electroluminescent element (hereinafter sometimes referred to as "the organic electroluminescent element of the present invention") manufactured using the composition of the present invention will be described.

[0148] Figure 1 It is a schematic cross-sectional view showing a structural example of the organic electroluminescent element 10 of the present invention. In Figure 1 , 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.

[0149] The organic electroluminescent element of the present invention has an anode, a light-emitting layer, and a cathode as essential constituent layers, but other functional layers may be provided between the anode 2 and the light-emitting layer 5 and between the cathode 9 and the light-emitting layer 5 as Figure 1 shown.

[0150] [Substrate]

[0151] The substrate 1 is a support for the organic electroluminescent element. As the substrate 1, a plate of quartz or glass, a metal plate or foil, a plastic film or sheet, etc. can be used. A glass plate; a plate of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, polysulfone, etc. is particularly preferred. In the case of using a synthetic resin substrate, it is preferable to pay attention to gas barrier properties. Since deterioration of the organic electroluminescent element caused by external air passing through the substrate is less likely to occur, the gas barrier property of the substrate 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 gas barrier properties is also one of the preferred methods.

[0152] [Anode]

[0153] The anode 2 is an electrode that functions to inject holes into the layer on the light-emitting layer 5 side.

[0154] The anode 2 is usually composed of a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black or a conductive polymer such as poly(3-methylthiophene), polypyrrole, polyaniline, etc.

[0155] The formation of the anode 2 is usually carried out by methods such as sputtering, vacuum evaporation, etc.

[0156] When forming the anode 2 using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., it is also possible to form the anode 2 by dispersing these fine particles, etc. in an appropriate binder resin solution and coating it on the substrate 1.

[0157] In the case of a conductive polymer, it is also possible to directly form a thin film on the substrate 1 by electrolytic polymerization.

[0158] It is also possible to form the anode 2 by coating a conductive polymer on the substrate 1 (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

[0159] The anode 2 is usually a single-layer structure, but can also be made into a laminated structure composed of multiple materials according to requirements.

[0160] The thickness of the anode 2 can be appropriately selected according to the required transparency, etc. When transparency is required, the transmittance of visible light is usually 60% or more, preferably 80% or more. At this time, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, usually 1000 nm or less, preferably about 500 nm or less. When opacity is sufficient, the thickness of the anode 2 is arbitrary. It is also possible to use the substrate 1 that also functions as the anode 2. It is also possible to laminate different conductive materials on the above anode 2.

[0161] For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, it is preferable to perform ultraviolet (UV) / ozone treatment on the surface of the anode 2, or perform oxygen plasma or argon plasma treatment.

[0162] [Hole injection layer]

[0163] 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.

[0164] The formation method of the hole injection layer 3 can be a vacuum evaporation method or a wet film formation method, and there is no particular limitation. From the viewpoint of reducing dark spots, the hole injection layer 3 is preferably formed by a wet film formation method.

[0165] The film thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually in the range of 1000 nm or less, preferably 500 nm or less.

[0166] (Hole transport material)

[0167] The composition for forming the hole injection layer usually contains a hole transport material and a solvent as constituent materials of the hole injection layer 3.

[0168] As long as the hole transport material is a compound having hole transport properties that is usually used for the hole injection layer 3 of an organic electroluminescent element, it can be a high molecular compound such as a polymer or a low molecular compound such as a monomer, but a high molecular compound is preferred.

[0169] As the hole transport material, from the viewpoint of the charge injection barrier from the anode 2 to the hole injection layer 3, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferred. Examples of the hole transport material include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds formed by connecting a tertiary amine with a fluorenyl group, hydrazone derivatives, silazane derivatives, silylamine derivatives, phosphineamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinyl derivatives, polythiophene vinyl derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon, etc.

[0170] In the present invention, the so-called derivative, for example, in the case of an aromatic amine derivative, includes the aromatic amine itself and a compound having an aromatic amine as a main skeleton, and can be a polymer or a monomer.

[0171] The hole transport material used as the material for the hole injection layer 3 may contain any one of such compounds alone, or may contain two or more. When two or more hole transport materials are contained, the combination thereof is arbitrary, and it is preferable to use one or two or more aromatic tertiary amine polymer compounds in combination with one or two or more other hole transport materials.

[0172] As the hole transport material, from the viewpoints of amorphousness and visible light transmittance, among the above examples, aromatic amine compounds are preferable, and aromatic tertiary amine compounds are particularly preferable. The aromatic tertiary amine compound also includes a compound having an aromatic tertiary amine structure, that is, a compound having a group derived from an aromatic tertiary amine.

[0173] The type of the aromatic tertiary amine compound is not particularly limited. From the viewpoint of uniform light emission brought about by the surface smoothing effect, a polymer compound (polymerization type compound in which repeating units are linked) having a weight average molecular weight of 1000 or more and 1000000 or less is further preferable. As a preferable example of the aromatic tertiary amine polymer compound, a polymer compound having a repeating unit represented by the following formula (1) or the following formula (11) can be cited.

[0174]

[0175] (In formula (1),

[0176] Ar 3 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent,

[0177] Ar 4 represents a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group which may have a substituent, or a divalent group formed by directly connecting or connecting a plurality of the aromatic hydrocarbon group and the aromatic heterocyclic group via a linking group)

[0178] In the above formula (1), when a plurality of aromatic hydrocarbon groups and aromatic heterocyclic groups are connected via a linking group, the linking group is a divalent linking group. For example, a group formed by connecting 1 to 30, preferably 1 to 5, more preferably 1 to 3 groups selected from an -O- group, a -C(=O)- group, and a (optionally substituted) -CH2- group in any order can be cited.

[0179] In the linking group, from the viewpoint of excellent hole injection into the light emitting layer, Ar in formula (1) 4 is preferably an aromatic hydrocarbon group or an aromatic heterocyclic group connected via a linking group represented by the following formula (2).

[0180]

[0181] (In formula (2),

[0182] d represents an integer from 1 to 10,

[0183] R 8 and R 9 each independently represents a hydrogen atom or an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group which may have substituents;

[0184] R 8 、R 9 when there are a plurality of them, they may be the same or different)

[0185]

[0186] In the above formula (11), j, k, l, m, n, p each independently represents an integer of 0 or more. Among them, l + m ≥ 1. Ar 11 、Ar 12 、Ar 14 each independently represents a divalent aromatic ring group having 30 or less carbon atoms which may have substituents. Ar 13 represents a divalent aromatic ring group having 30 or less carbon atoms which may have substituents 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 substituents, S 1 ~S 4 each independently is represented by a group represented by the following formula (13).

[0187] In addition, the aromatic ring group mentioned here means an aromatic hydrocarbon ring group and an aromatic heterocyclic group.

[0188] Examples of the aromatic ring group as Ar 11 、Ar 12 、Ar 14 include a monocyclic ring, a 2 - 6 fused ring, or a group formed by connecting two or more of these aromatic rings. Specific examples of the monocyclic or 2 - 6 fused ring aromatic ring group include those derived from a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzopyrene ring, ring, a benzo[a]phenanthrene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, a biphenyl group, a terphenyl group, a quaterphenyl group, a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a diazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thiophenopyrrole ring, a thiophenothiophene ring, a furanopyrrole ring, a furanofuran ring, a thiophenofuran ring, a benzoiso A divalent group of an azole 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, a peridine ring, a quinazoline ring, a quinazolinone ring or an azulene ring. Among them, from the aspects of efficiently delocalizing negative charges and excellent stability and heat resistance, 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.

[0189] As Ar 13 Examples of the aromatic ring group of, are the same as those of Ar 11 Ar 12 Ar 14 The same applies to the case of.

[0190]

[0191] In the above formula (12), R 11 represents an alkyl group, an aromatic ring group or a trivalent group composed of an alkyl group having 40 or less carbon atoms and an aromatic ring group, and they may also have substituents. R 12 represents an alkyl group, an aromatic ring group or a divalent group composed of an alkyl group having 40 or less carbon atoms and an aromatic ring group, and they may also have substituents. Ar 31 represents a monovalent aromatic ring group or a monovalent crosslinking group, and they may also have substituents. q represents 1 to 4. When q is 2 or more, multiple R 12 may be the same or different, and multiple Ar 31 may be the same or different. The asterisk (*) represents the bonding site to the nitrogen atom of formula (11).

[0192] As the aromatic ring group of R 11 preferably, it is a monocyclic or polycyclic aromatic ring group having 3 or more and 30 or less carbon atoms or a group formed by connecting 2 to 6 of them. As specific examples, trivalent groups derived from 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 them can be cited.

[0193] As the alkyl group of R 11 preferably, it includes a linear, branched or cyclic alkyl group having 1 or more and 12 or less carbon atoms. As specific examples, groups derived from methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane, octane, etc. can be cited.

[0194] As the group composed of an alkyl group having 40 or less carbon atoms and an aromatic ring group of R 11 preferably, a group formed by connecting a linear, branched or cyclic alkyl group having 1 or more and 12 or less carbon atoms with a monocyclic or polycyclic aromatic ring group having 3 or more and 30 or less carbon atoms or a group formed by connecting 2 to 6 of them can be cited.

[0195] 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 linking ring having 30 or fewer carbon atoms formed by linking them together.

[0196] As R 12 Specific examples of the alkyl group include divalent groups derived from methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane, octane, and the like.

[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 linking ring having 30 or fewer carbon atoms formed by linking them together.

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

[0199]

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

[0201]

[0202] In the above formula (13), x and y represent integers of 0 or more. Ar 21 and Ar 23 each independently represent a divalent aromatic ring group, and these groups may also have substituents. Ar 22 represents a monovalent aromatic ring group which may have substituents, R 13 represents an alkyl group, an aromatic ring group, or a divalent group composed of an alkyl group and an aromatic ring group, and they may also have substituents. Ar 32 represents a monovalent aromatic ring group or a monovalent crosslinking group, and these groups may also have substituents. The asterisk (*) represents the bonding site to the nitrogen atom of formula (11).

[0203] Examples of the aromatic ring group of Ar 21 and Ar 23 are the same as the case of Ar 11 and Ar 12 and Ar 14 respectively.

[0204] As Ar 22 、Ar 32 Examples of the aromatic ring group of, can be cited monocyclic, 2 to 6 fused rings or groups formed by connecting two or more of these aromatic rings. As a specific example, can be cited from benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzopyrene ring, ring, benzo[a]phenanthrene ring, acenaphthene ring, fluoranthene ring, fluorene ring, biphenyl group, terphenyl group, quaterphenyl group, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, diazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thiophenopyrrole ring, thiophenothiophene ring, furanopyrrole ring, furanofuran ring, thiophenofuran ring, benzois oxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, benzimidazole, peridine ring, quinazoline ring, quinazolinone ring or azulenyl monovalent group. Among them, from the aspect of efficiently delocalizing negative charges and excellent stability and heat resistance, preferably a monovalent group or biphenyl group from a benzene ring, naphthalene ring, fluorene ring, pyridine ring or carbazole ring.

[0205] Examples of the alkyl or aromatic ring group of R 13 are the same as those of R 12 .

[0206] Ar 32 The crosslinking group of is not particularly limited, and as preferred examples, can be cited groups from benzocyclobutene ring, naphthocyclobutene ring or oxetane ring, vinyl group, acryloyl group, etc.

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

[0208] [Substituent group W]

[0209] alkyl groups having 1 or more, preferably 10 or less, more preferably 8 or less carbon atoms such as methyl and ethyl; alkenyl groups having 2 or more, preferably 11 or less, more preferably 5 or less carbon atoms such as vinyl; alkynyl groups having 2 or more, preferably 11 or less, more preferably 5 or less carbon atoms such as ethynyl; alkoxy groups having 1 or more, preferably 10 or less, more preferably 6 or less carbon atoms such as methoxy and ethoxy; aryloxy groups having 4 or more, preferably 5 or more and preferably 25 or less, more preferably 14 or less carbon atoms such as phenoxy, naphthyloxy and pyridyloxy; alkoxycarbonyl groups having 2 or more, preferably 11 or less, more preferably 7 or less carbon atoms such as methoxycarbonyl and ethoxycarbonyl; dialkylamino groups having 2 or more, preferably 20 or less, more preferably 12 or less carbon atoms such as dimethylamino and diethylamino; diarylamino groups having 10 or more, preferably 12 or more and preferably 30 or less, more preferably 22 or less carbon atoms such as diphenylamino, xylidino and N-carbazolyl; arylalkylamino groups having 6 or more, more preferably 7 or more and preferably 25 or less, more preferably 17 or less carbon atoms such as phenylmethylamino; acyl groups having 2 or more and preferably 10 or less, more preferably 7 or less carbon atoms such as acetyl and benzoyl; halogen atoms such as fluorine atom and chlorine atom; haloalkyl groups having 1 or more and preferably 8 or less, more preferably 4 or less carbon atoms such as trifluoromethyl; alkylthio groups having 1 or more and preferably 10 or less, more preferably 6 or less carbon atoms such as methylthio and ethylthio; arylthio groups having 4 or more, preferably 5 or more and preferably 25 or less, more preferably 14 or less carbon atoms such as phenylthio, naphthylthio and pyridylthio; silyl groups having 2 or more, preferably 3 or more and preferably 33 or less, more preferably 26 or less carbon atoms such as trimethylsilyl and triphenylsilyl; silyloxy groups having 2 or more, preferably 3 or more and preferably 33 or less, more preferably 26 or less carbon atoms such as trimethylsilyloxy and triphenylsilyloxy; cyano group; aromatic hydrocarbon groups having 6 or more and preferably 30 or less, more preferably 18 or less carbon atoms such as phenyl and naphthyl; aromatic heterocyclic groups having 3 or more, preferably 4 or more and preferably 28 or less, more preferably 17 or less carbon atoms such as thienyl and pyridyl.

[0210] Among the above substituent groups W, from the viewpoint of improving solubility, alkyl groups or alkoxy groups are preferred, and from the viewpoints of charge transport property and stability, aromatic hydrocarbon groups or aromatic heterocyclic groups are preferred.

[0211] In particular, among the polymer compounds having the repeating unit represented by the formula (11), the polymer compound having the repeating unit represented by the following formula (14) has very high hole injection / transport property, and thus is preferred.

[0212]

[0213] In the above formula (14), R 21 ~R 25 each independently represents an arbitrary substituent. The specific examples of the substituents of R 21 ~R 25 are the same as the substituents described in the above [Substituent Group W].

[0214] s and t each independently represent an integer of 0 or more and 5 or less.

[0215] u, v, and w each independently represent an integer of 0 or more and 4 or less.

[0216] As a preferred example of the aromatic tertiary amine polymer compound, a polymer compound containing a repeating unit represented by the following formula (15) and / or formula (16) can be cited.

[0217]

[0218] In the above formula (15) and formula (16), Ar 45 , Ar 47 and Ar 48 each independently represent a monovalent aromatic hydrocarbon group which may have a substituent or a monovalent aromatic heterocyclic group which may have a substituent. Ar 44 and Ar 46 each independently represent a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. R 41 ~R 43 each independently represent a hydrogen atom or an arbitrary substituent.

[0219] Ar 45 , Ar 47 and Ar 48 The specific examples, preferred examples, examples of substituents that may be possessed, and preferred examples of substituents of Ar 22 are the same as those of Ar 44 and Ar 46 The specific examples, preferred examples, examples of substituents that may be possessed, and preferred examples of substituents of Ar 11 , Ar 12 and Ar 14 are the same as those of Ar 41 ~R 43 , it is preferably a hydrogen atom or a substituent described in the above [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.

[0220] Hereinafter, preferred specific examples of the repeating units represented by formula (15) and formula (16) applicable in the present invention are given, but the present invention is not limited to these.

[0221]

[0222] (Electron-accepting compound)

[0223] The composition for forming a hole injection layer preferably contains an electron-accepting compound as a constituent material of the hole injection layer 3.

[0224] The electron-accepting compound is preferably a compound having oxidizing power and the ability to accept one electron from the above-mentioned hole transport material. Specifically, as the electron-accepting compound, a compound having an electron affinity of 4.0 eV or more is preferred, and a compound of 5.0 eV or more is more preferred.

[0225] As such an electron-accepting compound, for example, one or more compounds selected from triarylboron compounds, metal halides, Lewis acids, organic acids, salts, salts of arylamines and metal halides, salts of arylamines and Lewis acids, etc. More specifically, as the electron-accepting compound, 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate, triphenylsulfonium tetrafluoroborate and other salts substituted with organic groups (International Publication No. 2005 / 089024, International Publication No. 2017 / 164268); iron(III) chloride (Japanese Patent Laid-Open No. 11-251067), high-valent inorganic compounds such as ammonium persulfate; cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris(pentafluorophenyl)borane (Japanese Patent Laid-Open No. 2003-31365); fullerene derivatives; iodine; sulfonate ions such as polystyrenesulfonate ions, alkylbenzenesulfonate ions, camphorsulfonate ions, etc. The electron-accepting compound can increase the conductivity of the hole injection layer 3 by oxidizing the hole transport material.

[0226] The electron-accepting compound can increase the conductivity of the hole injection layer 3 by oxidizing the hole transport material.

[0227] (Other constituent materials)

[0228] As the material of the hole injection layer 3, as long as the effects of the present invention are not significantly impaired, other components may be further contained in addition to the above-mentioned hole transport material and electron-accepting compound.

[0229] (Solvent)

[0230] At least one of the solvents of the composition for forming a hole injection layer used in the wet film-forming method is preferably a compound capable of dissolving the constituent materials of the hole injection layer 3.

[0231] When the composition for forming a hole injection layer is the composition of the present invention, the solvent is the above-mentioned first solvent and the above-mentioned second solvent of the present invention.

[0232] Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, etc.

[0233] Examples of the ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, etc.

[0234] Examples of the ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, etc.

[0235] Examples of the aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, methylnaphthalene, etc.

[0236] Examples of the amide solvents include N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0237] In addition, dimethyl sulfoxide, etc. can also be used.

[0238] Among them, aromatic esters and aromatic ethers are preferred.

[0239] These solvents can be used alone, or two or more of them can be used in any combination and ratio.

[0240] As long as the effects of the present invention are not significantly impaired, the concentration of the hole transport material in the composition for forming a hole injection layer is arbitrary. From the aspect of film thickness uniformity, the concentration of the hole transport material in the composition for forming a hole injection layer is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and further preferably 0.5% by weight or more. The concentration of the hole transport material in the composition for forming a hole injection layer is preferably 70% by weight or less, more preferably 60% by weight or less, and further preferably 50% by weight or less. From the aspect of being less likely to cause film thickness unevenness, a smaller concentration is preferred. In addition, from the aspect of being less likely to cause defects in the formed hole injection layer, a larger concentration is preferred.

[0241] (Formation of a hole injection layer by a wet film-forming method)

[0242] When forming the hole injection layer 3 by the wet film-forming method, a composition for film formation (composition for forming the hole injection layer) is usually prepared by mixing the material constituting the hole injection layer 3 with an appropriate solvent (solvent for the hole injection layer). The composition for forming the hole injection layer 3 is coated on a layer corresponding to the lower layer of the hole injection layer (usually the anode 2) by an appropriate method for film formation, and then dried, thereby forming the hole injection layer 3.

[0243] (Formation of the hole injection layer 3 by vacuum evaporation method)

[0244] When forming the hole injection layer 3 by vacuum evaporation method, for example, the hole transport layer 3 can be formed as follows. One or more of the materials constituting the hole injection layer 3 (the above-mentioned hole transport materials, electron-accepting compounds, etc.) are placed in a crucible provided in a vacuum container (when using two or more materials, they are placed in respective crucibles), and the inside of the vacuum container is evacuated to about 10 -4 Pa by an appropriate vacuum pump. Then, the crucible is heated (when using two or more materials, the respective crucibles are heated), and the evaporation amount is controlled to evaporate (when using two or more materials, the evaporation amount is independently controlled for each to evaporate), and the hole injection layer 3 is formed on the anode 2 of the substrate 1 placed opposite to the crucible. When using two or more materials, their mixture can also be placed in the crucible, heated and evaporated to form the hole injection layer 3.

[0245] The degree of vacuum during evaporation is not limited as long as the effects of the present invention are not significantly impaired. The degree of vacuum during evaporation is usually 0.1×10 -6 Torr (0.13×10 -4 Pa) or more and 9.0×10 -6 Torr (12.0×10 -4 Pa) or less. The evaporation rate is not limited as long as the effects of the present invention are not significantly impaired. The evaporation rate is usually or more and or less. The film-forming temperature during evaporation is not limited as long as the effects of the present invention are not significantly impaired. The film-forming temperature during evaporation is preferably 10°C or more and 50°C or less.

[0246] [Hole transport layer]

[0247] The hole transport layer 4 is a layer that transports holes from the anode 2 to the light-emitting layer 5. The hole transport layer 4 is not an essential layer for the organic electroluminescent element of the present invention. However, when the hole transport layer 4 is provided, usually the hole transport layer 4 is formed on the hole injection layer 3 in the presence of the hole injection layer 3, and is formed on the anode 2 in the absence of the hole injection layer 3.

[0248] The method for forming the hole transport layer 4 can be a vacuum evaporation method or a wet film formation method, without particular limitation. From the viewpoint of reducing dark spots, the hole transport layer 4 is preferably formed by a wet film formation method.

[0249] As the material for forming the hole transport layer 4, a material with high hole transportability and capable of efficiently transporting the injected holes is preferred. Therefore, the material for forming the hole transport layer 4 preferably has a small ionization potential, high transparency to visible light, a large hole mobility, excellent stability, and is not likely to generate impurities that become traps during manufacturing or use. In most cases, since the hole transport layer 4 is in contact with the light-emitting layer 5, it is preferably not to quench the light emission from the light-emitting layer 5 or not to form an exciplex with the light-emitting layer 5 to reduce the efficiency.

[0250] As the material for the hole transport layer 4, any material that has been used as a constituent material for the hole transport layer 4 in the past can be used. Examples of the material for the hole transport layer 4 include arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, fused polycyclic aromatic derivatives, metal complexes, etc.

[0251] Examples of the material for the hole transport layer 4 include polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinyl derivatives, polysiloxane derivatives, polythiophene derivatives, poly(phenylene vinylene) derivatives, etc. They can be any of alternating copolymers, random copolymers, block copolymers or graft copolymers. In addition, they can also be polymers with branches in the main chain and three or more at the terminal part, or so-called dendrimers.

[0252] Among them, as the material for the hole transport layer 4, polyarylamine derivatives or polyarylene derivatives are preferred.

[0253] Specific examples of polyarylamine derivatives and polyarylene derivatives include the derivatives described in Japanese Patent Laid-Open No. 2008-98619.

[0254] As the polyarylamine derivative, it is preferred to use the above-mentioned aromatic tertiary amine polymer compound.

[0255] When forming the hole transport layer 4 by a wet film formation method, after preparing a hole transport layer forming composition in the same manner as the formation of the above-mentioned hole injection layer 3, it is dried after wet film formation.

[0256] In the composition for forming the hole transport layer, in addition to the above-mentioned hole transport material, a solvent is also contained. The solvent used is the same as the solvent used in the composition for forming the above-mentioned hole injection layer. In addition, the film-forming conditions, drying conditions, etc. are also the same as those in the formation of the hole injection layer 3.

[0257] When the composition for forming the hole transport layer is the composition of the present invention, the solvent is the above-mentioned first solvent and the above-mentioned second solvent of the present invention.

[0258] When forming the hole transport layer 4 by vacuum evaporation, the film-forming conditions, etc. are also the same as those in the formation of the above-mentioned hole injection layer 3.

[0259] Considering factors such as the immersion of the low-molecular material in the light-emitting layer or the swelling of the hole transport material, the film thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, usually 300 nm or less, and preferably 200 nm or less.

[0260] [Light-emitting layer]

[0261] The light-emitting layer 5 is a layer that is excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between the electrodes to which an electric field is applied, and becomes the main light-emitting source. The light-emitting layer 5 is usually formed on the hole transport layer 4 in the presence of the hole transport layer 4, on the hole injection layer 3 in the absence of the hole transport layer 4 but in the presence of the hole injection layer 3, and on the anode 2 in the absence of both the hole transport layer 4 and the hole injection layer 3.

[0262] <Materials for light-emitting layer>

[0263] The materials for the light-emitting layer usually include a light-emitting material and a charge transport material that serves as a host.

[0264] <Light-emitting material>

[0265] As the light-emitting material, any known material that is usually used as the light-emitting material of an organic electroluminescent element can generally be applied, and there is no particular limitation as long as a substance that emits light at a desired emission wavelength and has good luminous efficiency is used. The light-emitting material can be a fluorescent light-emitting material or a phosphorescent light-emitting material, but from the viewpoint of internal quantum efficiency, a phosphorescent light-emitting material is preferred. Further preferably, the red light-emitting material and the green light-emitting material are phosphorescent light-emitting materials, and the blue light-emitting material is a fluorescent light-emitting material.

[0266] When the composition of the present invention is a composition for forming a light-emitting layer, the following phosphorescent light-emitting materials, fluorescent light-emitting materials, and charge transport materials are preferably used.

[0267] <Phosphorescent light-emitting material>

[0268] A phosphorescent material refers to a material that exhibits luminescence from an excited triplet state. For example, metal complex compounds having Ir, Pt, Eu, etc. are representative examples, and as the structure of the material, a structure containing a metal complex is preferred.

[0269] Among metal complexes, as phosphorescent organometallic complexes that emit light via the triplet state, Werner-type complexes or organometallic complex compounds containing a metal selected from Groups VIIB to IB of the long-period type periodic table (hereinafter, as long as not otherwise specified, referred to as the "periodic table", and in this case, the long-period type periodic table) as the central metal can be cited. As such phosphorescent materials, for example, the phosphorescent materials described in International Publication No. 2014 / 024889, International Publication No. 2015-087961, International Publication No. 2016 / 194784, and Japanese Patent Application Laid-Open No. 2014-074000 can be cited. It is preferably a compound represented by the following formula (201) or a compound represented by the following formula (205), and more preferably a compound represented by the following formula (201).

[0270]

[0271] In formula (201), ring A1 represents an aromatic hydrocarbon ring structure that may have a substituent or an aromatic heterocyclic ring structure that may have a substituent.

[0272] Ring A2 represents an aromatic heterocyclic ring structure that may have a substituent.

[0273] R 201 、R 202 Each independently represents a structure represented by formula (202), and "*" represents the bonding position to ring A1 or ring A2. R 201 、R 202 May be the same or different, and when there are multiple R 201 、R 202 Respectively, they may be the same or different.

[0274] Ar 201 、Ar 203 Each independently represents an aromatic hydrocarbon ring structure that may have a substituent or an aromatic heterocyclic ring structure that may have a substituent.

[0275] Ar 202 Represents an aromatic hydrocarbon ring structure that may have a substituent, an aromatic heterocyclic ring structure that may have a substituent, or an aliphatic hydrocarbon structure that may have a substituent.

[0276] The substituents bonded to ring A1, the substituents bonded to ring A2, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may bond to each other to form a ring.

[0277] B 201 -L 200 -B 202 represents an anionic bidentate ligand. B 201 and B 202 each independently represents a carbon atom, an oxygen atom or a nitrogen atom, and these atoms can be atoms constituting a ring. L 200 represents a single bond, or an atomic group that forms a bidentate ligand together with B 201 and B 202 B 201 -L 200 -B 202 When there are a plurality of them, they may be the same or different.

[0278] It should be noted that in Formula (201) and Formula (202),

[0279] i1 and i2 each independently represent an integer of 0 or more and 12 or less,

[0280] i3 represents an integer of 0 or more with the upper limit being the number that can be substituted on Ar 202

[0281] i4 represents an integer of 0 or more with the upper limit being the number that can be substituted on Ar 201

[0282] k1 and k2 each independently represent an integer of 0 or more with the upper limit being the number that can be substituted on Ring A1 and Ring A2,

[0283] z represents an integer of 1 to 3.

[0284] (Substituent)

[0285] In the absence of special instructions, as the substituent, a group selected from the following substituent group S is preferred.

[0286] <Substituent group S>

[0287] · Alkyl, preferably alkyl having 1 to 20 carbon atoms, more preferably alkyl having 1 to 12 carbon atoms, further preferably alkyl having 1 to 8 carbon atoms, particularly preferably alkyl having 1 to 6 carbon atoms.

[0288] · Alkoxy, preferably alkoxy having 1 to 20 carbon atoms, more preferably alkoxy having 1 to 12 carbon atoms, further preferably alkoxy having 1 to 6 carbon atoms.

[0289] · Aryloxy, preferably aryloxy having 6 to 20 carbon atoms, more preferably aryloxy having 6 to 14 carbon atoms, further preferably aryloxy having 6 to 12 carbon atoms, particularly preferably aryloxy having 6 carbon atoms. ​​

[0290] ·Heteroaryloxy, preferably heteroaryloxy having 3 to 20 carbon atoms, more preferably heteroaryloxy having 3 to 12 carbon atoms.

[0291] ·Alkylamino, preferably alkylamino having 1 to 20 carbon atoms, more preferably alkylamino having 1 to 12 carbon atoms.

[0292] ·Arylamino, preferably arylamino having 6 to 36 carbon atoms, more preferably arylamino having 6 to 24 carbon atoms.

[0293] ·Aralkyl, preferably aralkyl having 7 to 40 carbon atoms, more preferably aralkyl having 7 to 18 carbon atoms, still more preferably aralkyl having 7 to 12 carbon atoms.

[0294] ·Heteroaralkyl, preferably heteroaralkyl having 7 to 40 carbon atoms, more preferably heteroaralkyl having 7 to 18 carbon atoms.

[0295] ·Alkenyl, preferably alkenyl having 2 to 20 carbon atoms, more preferably alkenyl having 2 to 12 carbon atoms, still more preferably alkenyl having 2 to 8 carbon atoms, particularly preferably alkenyl having 2 to 6 carbon atoms.

[0296] ·Alkynyl, preferably alkynyl having 2 to 20 carbon atoms, more preferably alkynyl having 2 to 12 carbon atoms.

[0297] ·Aryl, preferably aryl having 6 to 30 carbon atoms, more preferably aryl having 6 to 24 carbon atoms, still more preferably aryl having 6 to 18 carbon atoms, particularly preferably aryl having 6 to 14 carbon atoms.

[0298] ·Heteroaryl, preferably heteroaryl having 3 to 30 carbon atoms, more preferably heteroaryl having 3 to 24 carbon atoms, still more preferably heteroaryl having 3 to 18 carbon atoms, particularly preferably heteroaryl having 3 to 14 carbon atoms.

[0299] ·Alkylsilyl, preferably alkylsilyl having 1 to 20 carbon atoms in the alkyl group, more preferably alkylsilyl having 1 to 12 carbon atoms in the alkyl group.

[0300] ·Arylsilyl, preferably arylsilyl having 6 to 20 carbon atoms in the aryl group, more preferably arylsilyl having 6 to 14 carbon atoms in the aryl group.

[0301] ·Alkylcarbonyl, preferably alkylcarbonyl having 2 to 20 carbon atoms.

[0302] ·Arylcarbonyl, preferably arylcarbonyl having 7 to 20 carbon atoms.

[0303] Regarding the above groups, one or more hydrogen atoms may be substituted with fluorine atoms, or one or more hydrogen atoms may be substituted with deuterium atoms.

[0304] Unless otherwise specified, an aryl group is an aromatic hydrocarbon ring and a heteroaryl group is an aromatic heterocyclic ring.

[0305] · A hydrogen atom, a deuterium atom, a fluorine atom, a cyano group or -SF5.

[0306] Among the above substituent groups S, preferred are an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, an arylsilyl group, and a group in which one or more hydrogen atoms of these groups are substituted with fluorine atoms, a fluorine atom, a cyano group or -SF5,

[0307] More preferred are an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, and a group in which one or more hydrogen atoms of these groups are substituted with fluorine atoms, a fluorine atom, a cyano group or -SF5,

[0308] Further preferred are an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, an arylsilyl group,

[0309] Particularly preferred are an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group,

[0310] Most preferred are an alkyl group, an arylamino group, an aralkyl group, an aryl group, a heteroaryl group.

[0311] Among these substituent groups S, a substituent selected from the substituent group S may be further present as a substituent. The preferred groups, more preferred groups, further preferred groups, particularly preferred groups, and most preferred groups of the substituent that can be present are the same as the preferred groups in the substituent group S.

[0312] (Ring A1)

[0313] Ring A1 represents an aromatic hydrocarbon ring structure which may have substituents or an aromatic heterocyclic ring structure which may have substituents.

[0314] As the aromatic hydrocarbon ring, an aromatic hydrocarbon ring having 6 to 30 carbon atoms is preferred. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring are preferred.

[0315] As the aromatic heterocyclic ring, an aromatic heterocyclic ring having 3 to 30 carbon atoms containing any one of a nitrogen atom, an oxygen atom or a sulfur atom as a heteroatom is preferred. Further preferred are a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring.

[0316] As ring A1, a benzene ring, a naphthalene ring, or a fluorene ring is more preferable, a benzene ring or a fluorene ring is particularly preferable, and a benzene ring is most preferable.

[0317] (Ring A2)

[0318] Ring A2 represents an aromatic heterocyclic structure which may have substituents.

[0319] As the aromatic heterocycle, an aromatic heterocycle having 3 to 30 carbon atoms containing any one of a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom is preferable. Specifically, a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, benzo oxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, a phenanthridine ring are exemplified. A pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, a benzothiazole ring, benzo oxazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring are preferable, a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring are more preferable, and a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, a quinoxaline ring, a quinazoline ring are most preferable.

[0320] (Combination of ring A1 and ring A2)

[0321] As a preferable combination of ring A1 and ring A2, when expressed as (ring A1 - ring A2), it is (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 - dioxazole ring), and (benzene ring - thiophene ring).

[0322] (Substituents of ring A1 and ring A2)

[0323] The substituents that ring A1 and ring A2 may have can be arbitrarily selected, but preferably one or more substituents selected from the above substituent group S.

[0324] (Ar 201 、Ar 202 、Ar 203 )

[0325] Ar 201 、Ar 203 Each independently represents an aromatic hydrocarbon ring structure which may have substituents or an aromatic heterocyclic structure which may have substituents.

[0326] Ar 202 represents an aromatic hydrocarbon ring structure which may have substituents, an aromatic heterocyclic structure which may have substituents, or an aliphatic hydrocarbon structure which may have substituents.

[0327] Ar 201 、 Ar 202 、 Ar 203 When any one of them is an aromatic hydrocarbon ring structure which may have substituents, as the aromatic hydrocarbon ring structure, it is preferably an aromatic hydrocarbon ring having 6 to 30 carbon atoms. Specifically, it is preferably a benzene ring, a naphthalene ring, an anthracene ring, a triphenyl ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, more preferably a benzene ring, a naphthalene ring, a fluorene ring, and most preferably a benzene ring.

[0328] Ar 201 、 Ar 202 When any one of them is a benzene ring which may have substituents, it is preferred that at least one benzene ring is bonded to the adjacent structure at the ortho or meta position, and more preferably at least one benzene ring is bonded to the adjacent structure at the meta position.

[0329] Ar 201 、 Ar 202 、 Ar 203 When any one of them is a fluorene ring which may have substituents, the 9-position and 9'-position of the fluorene ring preferably have substituents or are bonded to the adjacent structure.

[0330] Ar 201 、 Ar 202 、 Ar 203 When any one of them is an aromatic heterocyclic structure which may have substituents, as the aromatic heterocyclic structure, it is preferably an aromatic heterocycle having 3 to 30 carbon atoms containing any one of a nitrogen atom, an oxygen atom or a sulfur atom as a heteroatom. Specifically, a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, benzo oxazole 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, a dibenzothiophene ring are exemplified. It is preferably a pyridine ring, a pyrimidine ring, a triazine ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring.

[0331] Ar 201 、 Ar 202 、 Ar 203 When any one of them is a carbazole ring which may have substituents, the N-position of the carbazole ring preferably has a substituent or is bonded to the adjacent structure.

[0332] Ar 202 When it is an aliphatic hydrocarbon structure which may have substituents, it is a straight-chain, branched-chain or cyclic aliphatic hydrocarbon structure, preferably having 1 to 24 carbon atoms, more preferably having 1 to 12 carbon atoms, and still more preferably having 1 to 8 carbon atoms.

[0333] (i1, i2, i3, i4, k1, k2)

[0334] i1 and i2 each independently represent an integer from 0 to 12, preferably from 1 to 12, more preferably from 1 to 8, and even more preferably from 1 to 6. By being within this range, an improvement in solubility and charge transportability can be expected.

[0335] i3 preferably represents an integer from 0 to 5, more preferably from 0 to 2, and even more preferably 0 or 1.

[0336] i4 preferably represents an integer from 0 to 2, more preferably 0 or 1.

[0337] k1 and k2 each independently preferably represent an integer from 0 to 3, more preferably from 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0338] (Ar 201 、Ar 202 、Ar 203 (Preferred substituents))

[0339] Ar 201 、Ar 202 、Ar 203 The substituents that can be possessed can be arbitrarily selected, but are preferably one or more substituents selected from the above-mentioned substituent group S. The preferred groups are also as shown in the above-mentioned substituent group S, but more preferably unsubstituted (hydrogen atom), alkyl, aryl, particularly preferably unsubstituted (hydrogen atom), alkyl, and most preferably unsubstituted (hydrogen atom) or tert-butyl. Tert-butyl is preferably substituted on Ar 203 when Ar 203 is present, and is substituted on Ar 203 when Ar 202 is absent, and is substituted on Ar 202 and Ar 203 when both Ar 201 are absent.

[0340] (Preferred form of the compound represented by formula (201))

[0341] The compound represented by the above formula (201) is preferably a compound that satisfies any one or more of the following (I) to (IV).

[0342] (I) Phenylenyl linkage

[0343] The structure represented by formula (202) preferably has a structure of a group formed by connecting benzene rings, that is, a benzene ring structure, where i1 is from 1 to 6 and at least one of the above benzene rings is bonded to an adjacent structure at the ortho or meta position.

[0344] By having such a structure, an improvement in solubility and charge transportability can be expected.

[0345] (II) (Phenylene)-arylalkyl(alkyl)

[0346] It has a structure of an aromatic hydrocarbon group or an aromatic heterocyclic group in which an alkyl or arylalkyl group is bonded to ring A1 or ring A2, 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, and Ar 203 is a benzene ring structure, and i3 is 0 or 1. Preferably, Ar 201 is the above-mentioned aromatic hydrocarbon structure, more preferably a structure formed by linking 1 to 5 benzene rings, and even more preferably a single benzene ring.

[0347] By having such a structure, an improvement in solubility and charge transportability can be expected.

[0348] (III) Dendron

[0349] It has a structure in which a dendron is bonded to ring A1 or ring A2, for example, Ar 201 Ar 202 is a benzene ring structure, Ar 203 is a biphenyl or terphenyl structure, i1 and i2 are 1 to 6, i3 is 2, and j is 2.

[0350] By having such a structure, an improvement in solubility and charge transportability can be expected.

[0351] (IV) B 201 -L 200 -B 202

[0352] B 201 -L 200 -B 202 The structure shown is preferably the structure shown by the following formula (203) or the following formula (204).

[0353]

[0354] In formula (203), R 211 R 212 R 213 each independently represents a substituent.

[0355] In formula (204), ring B3 represents an aromatic heterocyclic structure containing a nitrogen atom that may have a substituent. Ring B3 is preferably a pyridine ring.

[0356] (Preferred phosphorescent materials)

[0357] As the phosphorescent material represented by the above formula (201), there is no particular limitation. As a preferable phosphorescent material, the following phosphorescent materials can be mentioned.

[0358]

[0359]

[0360] In addition, the phosphorescent material represented by the following formula (205) is also preferable.

[0361]

[0362] [In formula (205), M 2 represents a metal, and T represents a carbon atom or a nitrogen atom. R 92 to R 95 each independently represent a substituent. However, when T is a nitrogen atom, R 94 and R 95 do not exist.

[0363] In formula (205), as specific examples of M 2 , metals selected from Groups VIIB to IB of the periodic table can be mentioned. Among them, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold is preferably mentioned, and divalent metals such as platinum and palladium are particularly preferably mentioned.

[0364] In addition, in formula (205), R 92 and R 93 each independently represent 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.

[0365] Furthermore, when T is a carbon atom, R 94 and R 95 each independently represent a substituent represented by the same exemplars as R 92 and R 93 . In addition, when T is a nitrogen atom, R 94 or R 95 directly bonded to the T does not exist. In addition, R 92 to R 95 may further have a substituent. As the substituent, the above-mentioned substituents can be used. Furthermore, any two or more groups among R 92 to R 95 can be connected to each other to form a ring.

[0366] (Molecular weight)

[0367] The molecular weight of the phosphorescent light-emitting material is preferably 5000 or less, more preferably 4000 or less, and particularly preferably 3000 or less. In addition, the molecular weight of the phosphorescent light-emitting material is preferably 800 or more, more preferably 1000 or more, and further preferably 1200 or more. It is considered that by being in this molecular weight range, the phosphorescent light-emitting materials can be uniformly mixed with the charge transport material without agglomeration, and a light-emitting layer with high luminous efficiency can be obtained.

[0368] From the aspects of high Tg, melting point, decomposition temperature, etc., excellent heat resistance of the phosphorescent light-emitting material and the formed light-emitting layer, and aspects such as not easily occurring reduction of film quality caused by gas generation, recrystallization, migration of molecules, etc., or increase in impurity concentration accompanied by thermal decomposition of the material, the molecular weight of the phosphorescent light-emitting material is preferably large. On the other hand, from the aspect of easy purification of organic compounds, the molecular weight of the phosphorescent light-emitting material is preferably small.

[0369] <Charge transport material>

[0370] 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.

[0371] Specific examples of the skeleton with excellent charge transport properties include aromatic structure, aromatic amine structure, triarylamine structure, dibenzofuran structure, naphthalene structure, phenanthrene structure, phthalocyanine structure, porphyrin structure, thiophene structure, benzylphenyl structure, fluorene structure, quinacridone structure, benzo[ghi]perylene structure, carbazole structure, pyrene structure, anthracene structure, phenanthroline structure, quinoline structure, pyridine structure, pyrimidine structure, triazine structure, diazole structure or imidazole structure, etc.

[0372] As the electron transport material, from the viewpoint of being a material with excellent electron transport properties and relatively stable structure, compounds having a pyridine structure, pyrimidine structure, or triazine structure are more preferred, and compounds having a pyrimidine structure or triazine structure are further preferred.

[0373] The hole transport material is a compound having a structure with excellent hole transport properties. Among the above-mentioned central skeletons with excellent charge transport properties, as the structure with excellent hole transport properties, a carbazole structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure, or pyrene structure is preferred, and a carbazole structure, dibenzofuran structure, or triarylamine structure is further preferred.

[0374] The charge transport material for the light-emitting layer preferably has a condensed ring structure with 3 or more rings, more preferably a compound having 2 or more condensed ring structures with 3 or more rings or a compound having at least 1 condensed ring with 5 or more rings. By using these compounds, it is easy to obtain the effect of increasing the molecular rigidity and suppressing the degree of molecular motion in response to heat. Furthermore, from the viewpoints of charge transport properties and material durability, it is preferred that the condensed rings with 3 or more rings and the condensed rings with 5 or more rings have aromatic hydrocarbon rings or aromatic heterocycles.

[0375] As the condensed ring structure with 3 or more rings, specifically, an anthracene structure, a phenanthrene structure, a pyrene structure, a structure, a tetracene structure, a benzophenanthrene structure, a fluorene structure, a benzo[b]fluorene structure, an indenofluorene structure, an indolofluorene structure, a carbazole structure, an indolocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, a dibenzothiophene structure, etc. can be cited. From the viewpoints of charge transport properties and solubility, it is preferred to select at least 1 from a phenanthrene structure, a fluorene structure, an indenofluorene structure, a carbazole structure, an indolocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure. From the viewpoint of durability against charges, a carbazole structure or an indolocarbazole structure is further preferred.

[0376] In the present invention, from the viewpoint of the durability of the organic electroluminescent element against charges, it is preferred that at least one of the charge transport materials in the light-emitting layer is a material having a pyrimidine skeleton or a triazine skeleton.

[0377] 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 preferred 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 5000 or more and 1000000 or less, more preferably 10000 or more and 500000 or less, and further preferably 10000 or more and 100000 or less.

[0378] In addition, from the viewpoints of ease of synthesis and purification, ease of designing electron transport properties and hole transport properties, and ease of adjusting the viscosity when dissolved in a solvent, the charge transport material of the light-emitting layer is preferably a low molecule. When the charge transport material contained in the light-emitting layer is a low molecular material, the molecular weight is preferably 5000 or less, further preferably 4000 or less, particularly preferably 3000 or less, most preferably 2000 or less, preferably 300 or more, more preferably 350 or more, and further preferably 400 or more.

[0379] <Fluorescent light-emitting material>

[0380] As the fluorescent light-emitting material, there is no particular limitation, and a compound represented by the following formula (211) is preferred.

[0381]

[0382] In the above formula (211), Ar 241 represents an aromatic hydrocarbon condensed ring structure which may have substituents, and Ar 242 , Ar 243 each independently represents an alkyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group which may have substituents, or a group formed by bonding them. n41 is an integer of 1 to 4.

[0383] Ar 241 preferably represents an aromatic hydrocarbon condensed ring structure having 10 to 30 carbon atoms. As specific ring structures, naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, tetracene, perylene, etc. can be cited.

[0384] Ar 241 more preferably represents an aromatic hydrocarbon condensed ring structure having 12 to 20 carbon atoms. As specific ring structures, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, tetracene, perylene can be cited.

[0385] Ar 241 even more preferably represents an aromatic hydrocarbon condensed ring structure having 16 to 18 carbon atoms. As specific ring structures, fluoranthene, pyrene,

[0386] n41 is 1 to 4, preferably 1 to 3, even more preferably 1 to 2, and most preferably 2.

[0387] As the alkyl group of Ar 242 , Ar 243 , an alkyl group having 1 to 12 carbon atoms is preferred, and an alkyl group having 1 to 6 carbon atoms is more preferred.

[0388] As the aromatic hydrocarbon group of Ar 242 , Ar 243 , an aromatic hydrocarbon group having 6 to 30 carbon atoms is preferred, and an aromatic hydrocarbon group having 6 to 24 carbon atoms is more preferred. Most preferably, it is a phenyl group or a naphthyl group.

[0389] As the aromatic heterocyclic group of Ar 242 , Ar 243 , an aromatic heterocyclic group having 3 to 30 carbon atoms is preferred, and an aromatic hydrocarbon group having 5 to 24 carbon atoms is more preferred. Specifically, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group are preferred, and a dibenzofuranyl group is more preferred.

[0390] Ar 241 、Ar 242 、Ar 243The substituents that can be present are preferably groups selected from the above substituent group S, more preferably hydrocarbon groups contained in the substituent group S, and still more preferably hydrocarbon groups among the groups preferred as the substituent group S.

[0391] The charge transport material used together with the above fluorescent luminescent material is not particularly limited, and a charge transport material represented by the following formula (212) is preferred.

[0392]

[0393] In the above formula (212), R 251 , R 252 are each independently a structure represented by formula (213), R 253 represents a substituent, and when there are a plurality of R 253 , they may be the same or different, and n43 is an integer of 0 to 8.

[0394]

[0395] 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 that may have substituents or a heteroaromatic ring structure that may have substituents, and when there are a plurality of Ar 254 , Ar 255 respectively, they may be the same or different, n44 is an integer of 1 to 5, and n45 is an integer of 0 to 5.

[0396] Ar 254 is preferably a monocyclic or polycyclic aromatic hydrocarbon structure having 6 to 30 carbon atoms that may have substituents, and more preferably a monocyclic or polycyclic aromatic hydrocarbon structure having 6 to 12 carbon atoms that may have substituents.

[0397] Ar 255 is preferably a monocyclic or polycyclic aromatic hydrocarbon structure having 6 to 30 carbon atoms that may have substituents or a polycyclic aromatic heterocyclic structure having 6 to 30 carbon atoms that may have substituents. Ar 255 is more preferably a monocyclic or polycyclic aromatic hydrocarbon structure having 6 to 12 carbon atoms that may have substituents or a polycyclic aromatic heterocyclic structure having 12 carbon atoms that may have substituents.

[0398] n44 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0399] n45 is preferably an integer of 0 to 3, and more preferably 0 to 2.

[0400] As the substituents, R 253 , Ar 254 and Ar255 The substituents that can be included are preferably groups selected from the above-mentioned substituent group S. More preferably, they are hydrocarbon groups contained in the substituent group S, and even more preferably, they are hydrocarbon groups among the groups preferably used as the substituent group S.

[0401] The molecular weights of the fluorescent light-emitting material and the charge transport material are preferably 5000 or less, more preferably 4000 or less, particularly preferably 3000 or less, and most preferably 2000 or less. Additionally, they are preferably 300 or more, more preferably 350 or more, and even more preferably 400 or more.

[0402] [Hole blocking layer]

[0403] A hole blocking layer 6 can be provided between the light-emitting layer 5 and the electron injection layer 8 described later. The hole blocking layer 6 is a layer that further functions to block holes moving from the anode 2 from reaching the cathode 9 in the electron transport layer. The hole blocking layer 6 is a layer laminated on the light-emitting layer 5 in a manner that interfaces with the cathode 9 side of the light-emitting layer 5.

[0404] 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 in the direction of the light-emitting layer 5.

[0405] As the physical properties required for the material constituting the hole blocking layer 6, high electron mobility and low hole mobility, a large energy gap (the difference between HOMO and LUMO), and a high triplet excitation energy level (T1) can be cited. As materials for the hole blocking layer 6 that satisfy such conditions, for example, mixed ligand complexes such as bis(2-methyl-8-hydroxyquinoline)(phenol)aluminum and bis(2-methyl-8-hydroxyquinoline)(triphenylsilanol)aluminum, metal complexes such as bis(2-methyl-8-hydroxyquinoline)aluminum-μ-oxo-bis-(2-methyl-8-hydroxyquinoline)aluminum binuclear metal complexes, styryl compounds such as stilbenylbiphenyl derivatives (Japanese Patent Laid-Open No. 11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5(4-tert-butylphenyl)-1,2,4-triazole (Japanese Patent Laid-Open No. 7-41759), phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297), etc. Further, compounds having at least one pyridine ring substituted at the 2, 4, and 6 positions described in International Publication No. 2005 / 022962 are also preferably used as materials for the hole blocking layer 6.

[0406] 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, a vapor deposition method, or other methods.

[0407] As long as the effects of the present invention are not significantly impaired, the film thickness of the hole blocking layer 6 can be arbitrary. The film thickness of the hole blocking layer 6 is generally 0.3 nm or more, preferably 0.5 nm or more, generally 100 nm or less, and preferably 50 nm or less.

[0408] [Electron transport layer]

[0409] The electron transport layer 7 is a layer provided between the light layer 5 and the cathode 9 for transporting electrons.

[0410] As the electron transport material for the electron transport layer 7, a compound that has a high electron injection effect from the cathode 9 or the adjacent layer on the cathode 9 side and has a high electron mobility and can efficiently transport the injected electrons is usually used. As compounds satisfying such conditions, for example, metal complexes such as aluminum complexes and lithium complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, diazole derivatives, stilbenylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzo azole metal complexes, benzothiazole metal complexes, tribenzoimidazolylbenzene (U.S. Patent No. 5645948), quinoxaline compounds (Japanese Patent Laid-Open No. 6-207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimide, triazine compound derivatives, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, etc.

[0411] As the electron transport material used in the electron transport layer 7, by doping alkali metals such as sodium, potassium, cesium, lithium, and rubidium in electron-transporting organic compounds represented by nitrogen-containing heterocyclic compounds such as bathophenanthroline and metal complexes such as aluminum complexes of 8-hydroxyquinoline (described in Japanese Patent Laid-Open Nos. 10-270171, 2002-100478, 2002-100482, etc.), it is possible to achieve both electron injection and transport properties and excellent film quality, and thus it is preferred. In addition, doping inorganic salts such as lithium fluoride and cesium carbonate in the above electron-transporting organic compounds is also effective.

[0412] There is no limitation on the formation method of the electron transport layer 7. The electron transport layer 7 can be formed by a wet film-forming method, a vapor deposition method, or other methods.

[0413] As long as the effects of the present invention are not significantly impaired, the film thickness of the electron transport layer 7 can be arbitrary. The film thickness of the electron transport layer 7 is generally 1 nm or more, preferably 5 nm or more, generally 300 nm or less, and preferably 100 nm or less.

[0414] [Electron injection layer]

[0415] In order to efficiently inject electrons injected from the cathode 9 into the light-emitting layer 5, an electron injection layer 8 can 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.

[0416] As materials for the electron injection layer 8, for example, lithium fluoride (LiF), magnesium fluoride (MgF2), lithium oxide (Li2O), cesium (II) carbonate (CsCO3), etc. can be cited (refer to Applied Physics Letters, 1997, Vol. 70, pp. 152; Japanese Patent Laid-Open No. 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

[0417] In most cases, the electron injection layer 8 does not have charge transport properties. Therefore, in order to efficiently perform electron injection, it is preferably used in the form of an extremely thin film, and its film thickness is usually 0.1 nm or more, preferably 5 nm or less.

[0418] [Cathode]

[0419] The cathode 9 is an electrode that functions to inject electrons into the layer on the light-emitting layer 5 side.

[0420] As materials for the cathode 9, generally, metals such as aluminum, gold, silver, nickel, palladium, platinum, metal oxides such as oxides of indium and / or tin, metal halides such as copper iodide, carbon black, or conductive polymers such as poly(3-methylthiophene), polypyrrole, polyaniline, etc. can be cited. Among these, in order to efficiently perform electron injection, metals with a low work function are preferred. For example, appropriate metals such as tin, magnesium, indium, calcium, aluminum, silver, or their alloys can be used. As specific examples, alloy electrodes with a low work function such as magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy, etc. can be cited.

[0421] The material of the cathode 9 can use only one kind, or two or more kinds can be used in any combination and ratio.

[0422] The film thickness of the cathode 9 varies depending on the required transparency. When transparency is required, the transmittance of visible light is preferably usually 60% or more, preferably 80% or more. At this time, the thickness of the cathode 9 is usually 5 nm or more, preferably 10 nm or more, usually 1000 nm or less, preferably about 500 nm or less. When opacity is acceptable, the thickness of the cathode 9 is arbitrary, and the cathode can be the same as the substrate.

[0423] A different conductive material can also be laminated on the cathode 9.

[0424] For example, for the purpose of protecting a cathode including a low-work-function metal composed of alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, etc., a metal layer with a high work function and stable against the atmosphere is further laminated thereon, so that the stability of the element increases, which is thus preferable. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum, etc. can be used. These materials can be used alone, or two or more kinds can be used in any combination and ratio.

[0425] [Other layers]

[0426] The organic electroluminescent element of the present invention can have other configurations within the scope not departing from its gist. For example, as long as its performance is not impaired, any layer other than the layers described above can be provided between the anode 2 and the cathode 9, and in addition, layers that are not essential among the layers described above can also be omitted.

[0427] In the layer configuration described above, the components other than the substrate can also be laminated in the reverse order. For example, if it is Figure 1 such a layer configuration, other components can be provided on the substrate 1 in the order of the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, the hole injection layer 3, and the anode 2.

[0428] The organic electroluminescent element of the present invention can be configured as a single organic electroluminescent element, or can be applied to a configuration in which a plurality of organic electroluminescent elements are arranged in an array, or can also be applied to a configuration in which the anode and the cathode are arranged in an X-Y matrix.

[0429] In each of the above layers, as long as the effects of the present invention are not significantly impaired, components other than the components described as materials can also be included.

[0430] <Organic electroluminescent device>

[0431] Two or more organic electroluminescent elements that emit light in different colors can be provided to form an organic electroluminescent device such as an organic EL display device or an organic EL lighting. In this organic electroluminescent device, by using at least one, preferably all, of the organic electroluminescent elements of the present invention, a high-quality organic electroluminescent device can be provided.

[0432] <Organic EL display device>

[0433] There is no particular limitation on the model and structure of the organic EL display device using the organic electroluminescent element of the present invention, and the organic electroluminescent element of the present invention can be assembled according to a conventional method.

[0434] For example, an organic EL display device can be formed by the method described in "Organic EL Display" (published by Ohmsha, Ltd. on August 20, 2004, written by Seishi Toki, Chihaya Adachi, and Hideyuki Murata).

[0435] <Organic EL Lighting>

[0436] There are no particular restrictions on the model and 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 assembled according to a conventional method.

[0437] Examples

[0438] Hereinafter, examples are shown to illustrate the present invention more specifically. However, the present invention is not limited to the following examples, and the present invention can be arbitrarily modified and implemented as long as its gist is not deviated from.

[0439] [Solvents Used]

[0440] The physical properties of the solvents used in the following examples and comparative examples are shown in Table 1 below.

[0441] [Table 1]

[0442]

[0443] "-" in the table indicates not measured

[0444] [Evaluation I: Evaluation of Flatness at the Center of the Panel]

[0445] <Preparation of Substrate I>

[0446] An indium tin oxide (ITO) film was formed on a glass substrate with a thickness of 0.7 mm by sputtering. A liquid-repellent acrylic resin was coated on the obtained substrate by spin coating to a thickness of 1.7 μm, and openings were formed by a general photolithography method. The size of the openings was about 170 μm in the major axis and about 50 μm in the minor axis.

[0447] <Coating of Base Layer 1>

[0448] A composition for base layer 1 in which a base layer mainly composed of an arylamine polymer is dissolved in a solvent was prepared. Using an inkjet printer (DMP-2831 manufactured by Fujifilm Corporation), the composition for base layer 1 was coated on the above openings of substrate I, followed by vacuum drying and calcination to form a film with a thickness of about 30 nm.

[0449] <Coating of Base Layer 2>

[0450] A composition for the substrate layer 2 is prepared by dissolving a substrate layer mainly composed of an arylamine polymer in a solvent. Using an inkjet printer (DMP-2831 manufactured by Fujifilm Corporation), the composition for the substrate layer 2 is coated on the substrate layer 1 in the opening portion, followed by vacuum drying and calcination to form a film with a film thickness of approximately 20 nm.

[0451] <Preparation of Solid Component for Light-Emitting Layer Formation>

[0452] The charge injection and transport materials, compound (H-1) and compound (H-2), and the light-emitting material, (D-1), shown below are mixed in a weight ratio of 30:70:20 to prepare a solid component I-1 for forming a light-emitting layer.

[0453]

[0454] <Definition of Flatness>

[0455] The cross-sectional view when the organic film formed in the opening portion is divided by a plane perpendicular to the surface of the organic film is defined as the cross-sectional distribution of the organic film. The average film thickness Da of the organic film is calculated at 25% to 75% of the opening length in the cross-sectional distribution of the organic film. The region where the film thickness Do(x) of the organic film at a certain position x satisfies the following formula is defined as X1.

[0456] Da - Da×5% < Do(x) < Da + Da×5% (Formula 1)

[0457] When the length of the opening portion is defined as X2, the definition of flatness is defined as X1 / X2×100 (%).

[0458] <Reference Example 1>

[0459] Diethyl phthalate and cyclohexylbenzene are mixed in a weight ratio of 15:85 to prepare an organic solvent I-1. The solid component I-1 for forming a light-emitting layer is dissolved in the organic solvent I-1 to a concentration of 1.7% by weight to prepare a composition I-1 for forming a light-emitting layer.

[0460] Using an inkjet printer (DMP-2831 manufactured by Fujifilm Corporation), 5 droplets of the composition I-1 for forming a light-emitting layer are coated on the substrate layer 2 in the opening portion. Then, the organic solvent is removed by vacuum drying to dry the composition I-1 for forming a light-emitting layer, and it is calcined at 120 °C for 3 minutes to form a functional film, i.e., a light-emitting layer I-1.

[0461] In order to evaluate the flatness of the light-emitting layer I-1, an ITO substrate with an organic film formed thereon was measured using a stylus surface profiler (ET200 manufactured by Kosaka Laboratory Ltd.). The measurement of the surface step difference was performed by scanning in the long axis direction of the opening portion, obtaining the step difference distributions of the light-emitting layer I-1 near the center of two substrates, and averaging them to produce the step difference distribution of the light-emitting layer I-1. Similarly, the distributions of two uncoated opening portions were also obtained, averaged, and a blank profile was produced. Next, the two distributions of the light-emitting layer I-1 and the blank were overlapped and displayed to produce a cross-sectional view of how the organic film was formed in the opening portion. If the flatness was calculated according to the above definition, it was 93.8%. The distributions of the light-emitting layer I-1 and the blank are shown in Figure 1 。

[0462] <Reference Example 2>

[0463] 2-Phenoxyethyl acetate and ethyl benzoate were mixed so that the weight ratio was 30:70 to prepare an organic solvent I-2. The solid component I-1 for forming the light-emitting layer was dissolved in the organic solvent I-2 so as to be 1.7% by weight to prepare a composition I-2 for forming the light-emitting layer.

[0464] Using the composition I-2 for forming the light-emitting layer instead of the composition I-1 for forming the light-emitting layer, the light-emitting layer I-2 was formed in the same manner as in Reference Example 1 except for this, and its flatness was evaluated in the same manner. As a result, when calculated according to the above definition, it was 96.2%. The distributions of the light-emitting layer I-2 and the blank are shown in Figure 2 。

[0465] <Comparative Example 1>

[0466] Dibenzyl ether and cyclohexylbenzene were mixed so that the weight ratio was 20:80 to prepare an organic solvent I-3. The solid component I-1 for forming the light-emitting layer was dissolved in the organic solvent I-3 so as to be 1.7% by weight to prepare a composition I-3 for forming the light-emitting layer.

[0467] Using the composition I-3 for forming the light-emitting layer instead of the composition I-1 for forming the light-emitting layer, the light-emitting layer I-3 was formed in the same manner as in Reference Example 1 except for this, and its flatness was evaluated in the same manner. As a result, when calculated according to the above definition, it was 50.1%. The distributions of the light-emitting layer I-3 and the blank are shown in Figure 3 。

[0468] <Comparative Example 2>

[0469] 3-Phenoxytoluene and cyclohexylbenzene were mixed in a weight ratio of 20:80 to prepare an organic solvent I-4. The solid component I-1 for forming a light-emitting layer was dissolved in the organic solvent I-4 to a concentration of 1.7% by weight to prepare a composition I-4 for forming a light-emitting layer.

[0470] Using the composition I-4 for forming a light-emitting layer in place of the composition I-1 for forming a light-emitting layer, a light-emitting layer I-4 was formed in the same manner as in Reference Example 1, and its flatness was evaluated in the same manner. As a result, when calculated using the above definition, it was 67.7%. The distribution of the light-emitting layer I-4 and the blank is shown in Figure 4 .

[0471] <Comparative Example 3>

[0472] 2-Phenoxyethanol and cyclohexylbenzene were mixed in a weight ratio of 20:80 to prepare an organic solvent I-5. The solid component I-1 for forming a light-emitting layer was dissolved in the organic solvent I-5 to a concentration of 1.7% by weight to prepare a composition I-5 for forming a light-emitting layer.

[0473] Using the composition I-5 for forming a light-emitting layer in place of the composition I-1 for forming a light-emitting layer, a light-emitting layer I-5 was formed in the same manner as in Reference Example 1, and its flatness was evaluated in the same manner. As a result, when calculated using the above definition, it was 42.4%. The distribution of the light-emitting layer I-5 and the blank is shown in Figure 5 .

[0474] <Results of Reference Examples 1 and 2 and Comparative Examples 1 to 3>

[0475] The combinations of solvents and flatness of Reference Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 2.

[0476] [Table 2]

[0477]

[0478] <Consideration>

[0479] In Reference Examples 1 and 2, it was clearly shown from the distribution that, in addition to the improvement of the flat region, the wetting rise (hereinafter referred to as the meniscus) to the partition wall portion of the opening was very small, and the effective area of the light-emitting element became wider. By selecting the flow activation energy within an appropriate range, the useless flow of the liquid can be suppressed, and a flat organic film can be obtained.

[0480] In Comparative Examples 1 and 2, solvents with very low flow activation energies were designed for each other. Therefore, during the drying process, the liquid flowed, and the liquid flowed to the partition wall portion, so that the meniscus became wider. In addition, the liquid moved from the center to the partition wall. Therefore, although the same liquid droplets were placed, the film thickness was thinner than that in Reference Examples 1 and 2.

[0481] In Comparative Example 3, an organic solvent was designed in which the flow activation energy was set to a very high value. At this time, although the flow could be suppressed, it was speculated that since the liquid film did not wet and drop during the drying process, the meniscus became wider. That is, in order to obtain a flat organic film, fluidity for liquid wetting reduction was required at the initial stage of drying. On the other hand, at the end stage of drying, it was necessary to eliminate the fluidity to eliminate unnecessary liquid flow.

[0482] Based on the comparison between Reference Examples 1 and 2 and Comparative Examples 1 to 3 above, although Reference Examples 1 and 2 have excellent flatness at the opening, these Reference Examples 1 and 2 use a solvent with a boiling point less than 245°C as the second solvent. Therefore, as shown in Comparative Example 4 described later, the flatness at the panel end is significantly poor.

[0483] [Evaluation II: Evaluation of flatness at the center of the panel]

[0484] <Preparation of Substrate II>

[0485] A substrate II having at least 21 openings in the long axis direction and 65 openings in the short axis direction, with the long axis being approximately 170 μm and the short axis being approximately 50 μm, was produced in the same manner as the preparation of Substrate I in Evaluation I.

[0486] <Preparation of Solid Component>

[0487] A solid component II-1 was prepared by mixing the following hole transport material P-1 and electron-withdrawing dopant D-2 in a weight ratio of 100:10.

[0488]

[0489] <Definition of Flatness>

[0490] When the length of the above opening was set to La, the average film thickness Da in the region where the distance x from the opening end was 0.25 < x / La < 0.75 was calculated, and the region where the film thickness Do(x) of the organic film at a certain position x satisfied the following formula 2 was set as Lb.

[0491] Da - Da×5% < Do(x) < Da + Da×5% (Formula 2)

[0492] For the length La of the opening, the definition of flatness was set as Lb / La×100 (%).

[0493] <Example 1>

[0494] For 2-isopropylnaphthalene, it was adjusted so that the proportion of the solid component II-1 was 5% by weight, and while stirring with a stirrer at 420 rpm, it was heated at 110°C for 3 hours to produce a standard composition II-1.

[0495] The standard composition II-1, 2-isopropylnaphthalene, and 2-ethylhexyl benzoate were mixed at a weight ratio of 50:20.75:29.25 respectively. After stirring for a certain period of time, filtration was carried out using a membrane filter with a pore size of 0.2 μm to prepare composition II-1. Composition II-1 is a composition in which the concentration of solid component II-1 is 2.5% by weight and the weight ratio of 2-isopropylnaphthalene to 2-ethylhexyl benzoate is 70:30.

[0496] Using an inkjet printer (DMP-2831 manufactured by Fujifilm Corporation), composition II-1 was coated on the openings of substrate II, and vacuum drying was performed to obtain an organic film. After calcining the organic film on a heating plate at 130 °C for 3 minutes, it was calcined on a heating plate at 230 °C for 30 minutes to form organic film II-1. The coating amount was adjusted so that the dry film thickness was approximately 100 nm. Twenty-one openings in the length direction and sixty-five openings in the short-axis direction were coated, and in the short-axis direction, coating was performed in a pattern where one out of every five coatings was not coated, to form pixel group 1. Thus, pixel group 1 became a periodic structure in which the coated openings and the uncoated openings were repeated with a period of six openings in the short-axis direction.

[0497] In order to evaluate the flatness, a stylus type surface step gauge (ET200 manufactured by Kosaka Laboratory Ltd.) was used to measure the film thickness distribution in the short-axis direction of organic film II-1. The openings to be measured were set at the following two positions within the surface of pixel group 1 of 21×65.

[0498] Measurement site 1: Starting from the ends on both the long-axis and short-axis sides, the position of the 11th opening in the long-axis direction and the 33rd opening in the short-axis direction (the central region of pixel group 1)

[0499] Measurement site 2: Starting from the ends on both the long-axis and short-axis sides, the position of the 3rd opening in the long-axis direction and the 9th opening in the short-axis direction (the edge region of pixel group 1)

[0500] The flatness evaluation results of measurement site 1 are shown in Figure 7 and the flatness evaluation results of measurement site 2 are shown in Figure 8 . If the flatness of organic film 1 at the above two sites is calculated according to the definition of flatness in Equation 2, the flatness at measurement site 1 is 81.0% and the flatness at measurement site 2 is 84.3%, obtaining good flatness. In addition, the shapes of the films at measurement site 1 and measurement site 2 are approximately the same shape.

[0501] <Example 2>

[0502] For butyl benzoate, it was adjusted so that the proportion of solid component II-1 became 5% by weight, and while stirring with a stirrer at 420 rpm, it was heated at 110 °C for 3 hours to prepare standard composition II-2.

[0503] The standard composition II-2, butyl benzoate, and 2-ethylhexyl benzoate were mixed at a weight ratio of 50:20.75:29.25 respectively to prepare composition II-2. Composition II-2 is a composition in which the concentration of solid component II-1 is 2.5% by weight and the weight ratio of butyl benzoate to 2-ethylhexyl benzoate is 70:30.

[0504] Using composition II-2, an organic film II-2 was formed by the same steps as in Example 1, and the flatness was evaluated.

[0505] The flatness evaluation results of measurement site 1 are shown in Figure 9 and the flatness evaluation results of measurement site 2 are shown in Figure 10 . If the flatness of the organic film II-2 at the above two sites is calculated according to the definition of flatness in Equation 2, the flatness of measurement site 1 is 55.8% and that of measurement site 2 is 58.7%, obtaining good flatness. In addition, the shapes of the films at measurement site 1 and measurement site 2 are substantially the same shape.

[0506] <Example 3>

[0507] The standard composition II-1, 2-isopropylnaphthalene, 2-ethylhexyl benzoate, and benzyl benzoate were mixed at a weight ratio of 50:20.75:29.25 respectively, stirred for a certain time, and then filtered through a membrane filter with a pore size of 0.2 μm to prepare composition II-3. Composition II-3 is a composition in which the concentration of solid component II-1 is 2.5% by weight and the weight ratio of 2-isopropylnaphthalene, 2-ethylhexyl benzoate to benzyl benzoate is 70:20:10.

[0508] Using composition II-3, an organic film II-3 was formed by the same steps as in Example 1, and the flatness was evaluated.

[0509] The flatness evaluation results of measurement site 1 are shown in Figure 11 . If the flatness of the organic film II-3 is calculated according to the definition of flatness in Equation 2, the flatness of measurement site 1 is 90.2%, obtaining good flatness.

[0510] <Comparative Example 4>

[0511] The standard composition II-1, 2-isopropylnaphthalene, and dibenzyl ether were mixed at a weight ratio of 50:20.75:29.25, and after stirring for a certain time, they were filtered using a membrane filter with a pore size of 0.2 μm to prepare composition II-4. Composition II-4 is a composition in which the concentration of solid component II-1 is 2.5% by weight and the weight ratio of 2-isopropylnaphthalene to dibenzyl ether is 70:30.

[0512] Using composition II-4, an organic film II-4 was formed by the same procedure as in Example 1, and the flatness was evaluated.

[0513] The flatness evaluation results of measurement site 1 are shown in Figure 12 and the flatness evaluation results of measurement site 2 are shown in Figure 13 . If the flatness of the organic film II-4 at the above two sites is calculated according to the definition of flatness in Equation 2, the flatness of measurement site 1 is 16.2% and that of measurement site 2 is 31.5%, and a flat film was not obtained. The shapes of the films at measurement site 1 and measurement site 2 were concave in the central part and did not become the same shape.

[0514] <Comparative Example 5>

[0515] For cyclohexylbenzene, the proportion of solid component II-1 was adjusted to be 5% by weight, and while stirring with a stirrer at 420 rpm, it was heated at 110 °C for 3 hours to prepare standard composition II-3.

[0516] The standard composition II-3, cyclohexylbenzene, and 2-ethylhexyl benzoate were mixed at a weight ratio of 50:20.75:29.25 to prepare composition II-5. Composition II-5 is a composition in which the concentration of solid component II-1 is 2.5% by weight and the weight ratio of cyclohexylbenzene to 2-ethylhexyl benzoate is 70:30.

[0517] Using composition II-5, an organic film II-5 was formed by the same procedure as in Example 1, and the flatness was evaluated.

[0518] The flatness evaluation results of measurement site 1 are shown in Figure 14 and the flatness evaluation results of measurement site 2 are shown in Figure 15 . If the flatness of the organic film II-5 at the above two sites is calculated according to the definition of flatness in Equation 2, the flatness of measurement site 1 is 68.9%, and good flatness was obtained, but the flatness of measurement site 2 is 4.1%, and a flat film was not obtained.

[0519] <Comparative Example 6>

[0520] For 2-ethylhexyl benzoate, adjust it so that the proportion of solid component II-1 becomes 2.5% by weight. While stirring with a stirrer at 420 rpm, heat it at 110 °C for 3 hours to prepare Composition II-6.

[0521] Using Composition II-6, form an organic film II-6 by the same steps as in Example 1 above, and evaluate the flatness.

[0522] Show the flatness evaluation results of Measurement Site 1 in Figure 16 , and show the flatness evaluation results of Measurement Site 2 in Figure 17 . If the flatness of the organic film II-6 at the above two sites is calculated according to the definition of flatness in Equation 2, the flatness of Measurement Site 1 is 43.3%, and the flatness of Measurement Site 2 is 53.4%, and a flat film is not obtained. The shapes of the films at Measurement Site 1 and Measurement Site 2 are substantially the same shape.

[0523] Summarize the results of Examples 1 to 3 and Comparative Examples 4 to 6 in Table 3. From these results, it can be seen that when the boiling point of the second solvent is 245 °C or higher, the same flatness is obtained at the central part and the end part of the panel. It can be seen that especially when the boiling point of the second solvent is 260 °C or higher, a flatness of more than 80% is obtained at both the central part and the end part of the panel.

[0524] [Table 3]

[0525]

[0526] ※The content in parentheses is the boiling point (°C): Flow activation energy (kJ / mol)

[0527] The present invention has been described in detail in a specific manner, but various changes are obvious to those skilled in the art without departing from the intention and scope of the present invention.

[0528] This application is based on Japanese Patent Application 2018-088327 filed on May 1, 2018, and the entire content thereof is incorporated herein by reference.

[0529] Symbol Explanation

[0530] 1 Substrate

[0531] 2 Anode

[0532] 3 Hole Injection Layer

[0533] 4 Hole Transport Layer

[0534] 5 Light Emitting Layer

[0535] 6 Hole Blocking Layer

[0536] 7 Electron Transport Layer

[0537] 8 Electron injection layer

[0538] 9 Cathode

[0539] 10 Organic light-emitting device

Claims

1. A composition comprising a functional material, a first solvent, and a second solvent, The first solvent is a water-insoluble aromatic solvent, The boiling point of the first solvent is higher than that of the second solvent, and the difference in boiling points between the first solvent and the second solvent is 10 °C or more, The flow activation energy of the first solvent is 22 kJ / mol or more and 35 kJ / mol or less, The flow activation energy of the first solvent is 5 kJ / mol or more greater than that of the second solvent, The content ratio of the first solvent is 5 to 50% by weight based on the total amount of the first solvent and the second solvent, The total content of the first solvent and the second solvent is 90% by weight or more based on the total amount of the solvents in the composition, The boiling point of the second solvent is 245 °C or more, The first solvent and the second solvent are each independently any one of naphthalene with or without substituents, benzoate with or without substituents, and aromatic ether with or without substituents, The functional material is an aromatic tertiary amine polymer compound having a weight average molecular weight of 1,000 to 1,000,000.

2. The composition according to claim 1, wherein, The aromatic tertiary amine polymer compound is a polymer compound having a repeating unit represented by the following formula (11), in the formula (11), j, k, l, m, n, and p each independently represent an integer of 0 or more. Among them, l + m ≥ 1, Ar 11 、 Ar 12 、 Ar 14 each independently represents a divalent aromatic ring group having 30 or fewer carbon atoms which may have substituents. As the aromatic ring group, it is a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzopyrene ring, ring, benzophenanthrene ring, acenaphthene ring, fluoranthene ring, fluorene ring, biphenyl group, terphenyl group, quaterphenyl group, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, diazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thiophenopyrrole ring, thiophenothiophene ring, furanopyrrole ring, furanofuran ring, thiophenofuran ring, benzoiso oxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, peridine ring, quinazoline ring, quinazolinone ring, azulene ring or a divalent group formed by connecting two or more of these aromatic rings Ar 13 represents a divalent aromatic ring group having 30 or fewer carbon atoms which may have substituents, or a divalent group represented by the following formula (12), and the aromatic ring group and the said Ar 11 , Ar 12 , Ar 14 Similarly, Q 11 、Q 12 each independently represents an oxygen atom, a sulfur atom, or a hydrocarbon chain having 6 or fewer carbon atoms which may have substituents S 1 ~S 4 Each independently represented by the group shown in the following formula (13), In the formula (12), R 11 represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an aromatic ring group, or a trivalent group composed of an alkyl group having 40 or less carbon atoms and an aromatic ring group, that is, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms is connected to one or 2 to 6 aromatic ring groups which are monocyclic or condensed ring aromatic ring groups having 3 to 30 carbon atoms. The aromatic ring group is a trivalent group of 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 them, and they may also have substituents. R 12 represents an alkyl group, an aromatic ring group, or a divalent group composed of an alkyl group and an aromatic ring group with 40 or fewer carbon atoms. As the alkyl group, it is a divalent group of methane, ethane, propane, isopropane, butane, isobutane, pentane, hexane, and octane. As the aromatic ring group, it is a divalent group of a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a linked ring with 30 or fewer carbon atoms formed by linking them. They may also have substituents. Ar 31 represents a monovalent aromatic ring group or a monovalent crosslinking group. As the monovalent aromatic ring group, it is a monovalent group of a benzene ring, a fluorene ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a linking ring with 30 or less carbon atoms formed by connecting them. As the monovalent crosslinking group, it is a monovalent group of a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, or an acryloyl group. These groups may also have substituents. q represents 1 to 4, When q is 2 or more, multiple Rs 12 may be the same or different, and multiple Ars 31 may be the same or different, the asterisk (*) represents the bonding site to the nitrogen atom of the formula (11), the substituent that may be present is selected from the following substituent group W, in the formula (13), x and y represent integers of 0 or more, Ar 21 、Ar 23 each independently represents a divalent aromatic ring group, and these groups may also have substituents Ar 22 represents a monovalent aromatic ring group which may have substituents, R 13 represents an alkyl group, an aromatic ring group, or a divalent group composed of an alkyl group and an aromatic ring group, which may also have substituents Ar 32 represents a monovalent aromatic ring group or a monovalent crosslinking group, and these groups may also have substituents the asterisk (*) represents the bonding site to the nitrogen atom of the formula (11), As Ar 21 、Ar 23 's aromatic ring group, similar to the case of Ar 11 、Ar 12 、Ar 14 as well, As R 13 of the alkyl or aromatic ring group, and R 12 Similarly, As Ar 32 a monovalent crosslinking group is a monovalent group of a benzocyclobutene ring, a naphthocyclobutene ring or an oxetane ring, a vinyl group, or an acryloyl group, the substituent that may be present is selected from the following substituent group W, Substituent group W: an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 11 carbon atoms; an alkynyl group having 2 to 11 carbon atoms; an alkoxy group having 1 to 10 carbon atoms; an aryloxy group having 4 to 25 carbon atoms; an alkoxycarbonyl group having 2 to 11 carbon atoms; a dialkylamino group having 2 to 20 carbon atoms; a diarylamino group having 10 to 30 carbon atoms; an arylalkylamino group having 6 to 25 carbon atoms; an acyl group having 2 to 10 carbon atoms; a halogen atom; a haloalkyl group having 1 to 8 carbon atoms; an alkylthio group having 1 to 10 carbon atoms; an arylthio group having 4 to 25 carbon atoms; a silyl group having 2 to 33 carbon atoms; a siloxy group having 2 to 33 carbon atoms; a cyano group; an aromatic hydrocarbon group having 6 to 30 carbon atoms; an aromatic heterocyclic group having 3 to 28 carbon atoms.

3. The composition according to claim 1, wherein, The flow activation energy of the first solvent is 23 kJ / mol or more.

4. The composition according to claim 1, wherein, The flow activation energy of the first solvent is 24 kJ / mol or more.

5. The composition according to claim 1, wherein, The flow activation energy of the first solvent is 34 kJ / mol or less.

6. The composition according to claim 1, wherein, The flow activation energy of the first solvent is 32 kJ / mol or less.

7. The composition according to claim 1, wherein, The flow activation energy of the first solvent is 30 kJ / mol or less.

8. The composition according to any one of claims 1 to 7, wherein, Relative to the total amount of the solvents in the composition, the content of the first solvent is 5% by weight or more and 50% by weight or less.

9. The composition according to any one of claims 1 to 7, wherein,Relative to the total amount of the solvents in the composition, the content of the first solvent is 5% by weight or more and 30% by weight or less.

10. The composition according to any one of claims 1 to 7, wherein Relative to the total amount of the solvents in the composition, the content of the first solvent is 10% by weight or more and 50% by weight or less.

11. The composition according to any one of claims 1 to 7, wherein The viscosity of the second solvent at 23°C is 5 mPas or less.

12. The composition according to any one of claims 1 to 7, wherein The viscosity of the second solvent at 23°C is 4.5 mPas or less.

13. The composition according to any one of claims 1 to 7, wherein The viscosity of the second solvent at 23°C is 1.0 mPas or more.

14. The composition according to any one of claims 1 to 7, wherein The viscosity of the first solvent at 23°C is 3 mPas or more and 20 mPas or less.

15. The composition according to any one of claims 1 to 7, wherein The difference between the boiling point of the first solvent and the boiling point of the second solvent is 25°C or more.

16. The composition according to any one of claims 1 to 7, wherein The difference between the boiling point of the first solvent and the boiling point of the second solvent is 30°C or more.

17. The composition according to any one of claims 1 to 7, wherein The boiling point of the first solvent is 400°C or less, and the boiling point of the second solvent is 370°C or less.

18. The composition according to claim 1, wherein The difference between the flow activation energy of the first solvent and the flow activation energy of the second solvent is 5.2 kJ / mol or more.

19. The composition according to claim 1, wherein The difference in the flow activation energy between the first solvent and the second solvent is 5.5 kJ / mol or more.

20. The composition according to claim 1, wherein The difference in the flow activation energy between the first solvent and the second solvent is 21.0 kJ / mol or less.

21. The composition according to claim 1, wherein The difference in the flow activation energy between the first solvent and the second solvent is 20.0 kJ / mol or less.

22. The composition according to any one of claims 1 to 7, wherein The surface tension of the first solvent is 30 mN / m or more.

23. The composition according to any one of claims 1 to 7, wherein The surface tension of the first solvent is 45 mN / m or less.

24. The composition according to any one of claims 1 to 7, wherein The first solvent is any one of 2-ethylhexyl benzoate, benzyl benzoate, acetylnaphthalene, dimethyl phthalate, and diethyl phthalate. The second solvent is any one of methylnaphthalene, ethylnaphthalene, isopropylnaphthalene, methoxynaphthalene, butyl benzoate, and pentyl benzoate.

25. The composition according to claim 24, wherein The combination of the first solvent and the second solvent is a combination of 2-ethylhexyl benzoate and methylnaphthalene, 2-ethylhexyl benzoate and ethylnaphthalene, 2-ethylhexyl benzoate and isopropylnaphthalene, 2-ethylhexyl benzoate and butyl benzoate, 2-ethylhexyl benzoate and isopentyl benzoate, benzyl benzoate and methylnaphthalene, benzyl benzoate and ethylnaphthalene, benzyl benzoate and isopropylnaphthalene, benzyl benzoate and butyl benzoate, or benzyl benzoate and isopentyl benzoate.

26. A method for manufacturing an organic light-emitting device, comprising a step of wet film formation using the composition according to any one of claims 1 to 25.

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