WO2020262418A1 - Charge-transporting varnish - Google Patents

Abstract

Provided is a charge-transporting varnish which comprises (A) zirconia particles which are surface modified with a surface treating agent, (B) a monodispersed charge-transporting organic compound, and (C) an organic solvent.

Description

Charge transport varnish

The present invention relates to a charge transporting varnish.

The method for forming an organic functional layer such as a hole injection layer used in an organic electroluminescence (EL) device is roughly classified into a dry process represented by a vapor deposition method and a wet process represented by a spin coating method. Comparing each of these processes, the wet process can efficiently produce a thin film having a large area and high flatness. Therefore, at present, the area of organic EL displays is being increased, and a hole injection layer that can be formed by a wet process is desired. In view of these circumstances, the applicant has applied a charge transporting material that can be applied to various wet processes and provides a thin film capable of realizing excellent EL device characteristics when applied to a hole injection layer of an organic EL device. In addition, we have been developing compounds with good solubility in organic solvents used for them (see, for example, Patent Documents 1 to 3).

On the other hand, various incorporations have been made so far in order to improve the performance of organic EL elements. For example, efforts are being made to adjust the refractive index of the functional film used for the purpose of improving the light extraction efficiency. Specifically, the height of the device is increased by using a hole injection layer or a hole transport layer having a relatively high or low refractive index in consideration of the overall configuration of the device and the refractive index of other adjacent members. Attempts have been made to improve efficiency (see, for example, Patent Documents 4 and 5). As described above, the refractive index is an important factor in the design of the organic EL element, and in the material for the organic EL element, the refractive index is also considered to be an important physical property value to be considered.

Further, in recent years, the charge-transporting thin film for organic EL elements has been in the visible region because the coloring of the charge-transporting thin film used for the organic EL element reduces the color purity and color reproducibility of the organic EL element. It is desired to have high transparency and high transparency (see, for example, Patent Document 6). The applicant has already found a material for a wet process that suppresses coloring in the visible region and provides a charge-transporting thin film having excellent transparency (see, for example, Patent Documents 6 and 7), but of an organic EL display. Currently, as the area is being increased, the development of organic EL displays using the wet process is being vigorously carried out, and the materials for the wet process that provide a highly transparent charge-transporting thin film are available. Always sought after.

By the way, in the manufacture of an organic EL display, when a hole injection layer or another organic functional layer is formed by a wet process, a partition wall (bank) is generally provided so as to surround the layer forming region, and the partition wall is opened. Organic functional ink is applied to the inside of the part. At this time, the ink applied in the opening may crawl up on the side surface of the partition wall, and the thickness of the peripheral portion of the coating film in contact with the side surface of the partition wall may be thicker than that of the central portion of the coating film, so-called crawling phenomenon may occur. .. When such a crawling phenomenon occurs, the plurality of organic functional layers formed between the electrodes do not function in the order of stacking, causing a situation in which a leak current path is formed. As a result, the desired device characteristics cannot be realized. Further, the organic functional layer such as the crawling hole injection layer may cause uneven light emission of the obtained organic EL element. Patent Documents 8 and 9 propose means for suppressing the crawling phenomenon, but in response to the recent situation in which the development of organic EL displays using a wet process is further accelerated, the suppression of such a crawling phenomenon is suppressed. The demand for technology related to is increasing.

International Publication No. 2008/129947 International Publication No. 2015/050253 International Publication No. 2017/217457 Special Table 2007-536718 Special Table 2017-501585 International Publication No. 2013/0426223 International Publication No. 2008/032616 JP-A-2009-104859 Japanese Unexamined Patent Publication No. 2011-103222

The present invention has been made in view of the above circumstances, and is a charge that suppresses the creeping phenomenon, provides a thin film having a high refractive index and high transparency, and provides a charge transporting thin film suitable as a functional layer of an organic EL element. It is intended to provide a transportable varnish.

As a result of diligent studies to achieve the above object, the present inventor is obtained from a charge transport varnish containing zirconia particles surface-modified with a surface treatment agent, a monodisperse charge transport organic compound, and an organic solvent. The thin film exhibits high charge transportability, high transparency (low k value) and high refractive index (high n value), and when the varnish is applied into the partition wall by a wet process, the varnish creeping up is extremely suppressed. The present invention has been completed by finding that a thin film can be produced.

That is, the present invention provides the following charge transporting varnish.
1. 1. A charge-transporting varnish containing (A) zirconia particles surface-modified with a surface treatment agent, (B) a monodisperse charge-transporting organic compound, and (C) an organic solvent.
2. 2. A charge-transporting varnish having an average particle size of 2 to 100 nm for zirconia particles surface-modified with the surface treatment agent.
3. 3. One or two charge-transporting varnish in which the charge-transporting organic compound contains at least one selected from an arylamine derivative, a thiophene derivative and a pyrrole derivative.
4. 3. The charge-transporting varnish in which the charge-transporting organic compound contains an arylamine derivative.
5. A charge-transporting varnish according to any one of 1 to 4, wherein the charge-transporting organic compound has a molecular weight of 200 to 9,000.
6. The charge-transporting varnish according to any one of 1 to 5, wherein the charge-transporting organic compound is dissolved in the organic solvent.
7. Further, the charge transporting varnish according to any one of 1 to 6 containing (D) dopant.
8. (D) A charge-transporting varnish of 7 in which the dopant is an aryl sulfonic acid ester compound.
A charge-transporting thin film obtained from the charge-transporting varnish according to any one of 9.1 to 8.
An organic EL device including a charge transporting thin film of 10.9.
11. Ten organic EL devices in which the charge transporting thin film is a hole injection layer or a hole transport layer.

By using the charge-transporting varnish of the present invention, it is possible to produce a charge-transporting thin film in which the varnish creeps up (so-called pile-up) is extremely suppressed even when it is applied into the partition wall by a wet process. Further, the charge-transporting thin film obtained from the charge-transporting varnish of the present invention is excellent in flatness and charge-transporting property, and has high transparency and high refractive index. Therefore, the charge-transporting thin film obtained from the charge-transporting varnish of the present invention can be suitably used as a thin film for electronic devices such as organic EL devices.

It is a figure which shows the shape of the charge transport thin film in the partition wall of the substrate with a charge transport thin film obtained in Example 4. FIG.

[Charge transport varnish]
The charge-transporting varnish of the present invention includes (A) zirconia particles surface-modified with a surface treatment agent (hereinafter, also referred to as surface-modified zirconia particles), (B) a monodisperse charge-transporting organic compound, and (C). It contains an organic solvent.

[(A) Surface-modified zirconia particles]
The surface-modified zirconia (ZrO ₂ ) particles of the component (A) are obtained by surface-treating the nuclear particles made of zirconia with a surface treatment agent. Examples of the surface treatment agent include n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, phenyltrimethoxysilane, and 2- [methoxy (polyethyleneoxy) propyl]. -Trimethoxysilane, methoxytri (ethyleneoxy) propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- (methacryloyloxy) propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane , 3-Isocyanatopropyltrimethoxysilane, silane coupling agents such as glycidoxypropyltrimethoxysilane; heptanol, hexanol, octanol, benzyl alcohol, phenol, ethanol, propanol, butanol, oleyl alcohol, dodecyl alcohol, octadecanol. Alcohols such as; glycol ethers such as triethylene glycol monomethyl ether; carboxylic acids such as octanoic acid, acetic acid, propionic acid, 2- [2- (2-methoxyethoxy) ethoxy] acetic acid, oleic acid, stearic acid, benzoic acid and the like. Can be mentioned.

The average particle size of the nuclear particles is preferably 1 to 90 nm, more preferably 2 to 45 nm, and even more preferably 3 to 18 nm. Examples of the method for measuring the average particle size of the nuclear particles include a method using a transmission electron microscope (TEM). Various methods for measuring the average particle size using TEM are known, and one example thereof is a method based on the equivalent circle diameter. This is a method of obtaining the equivalent circle diameter of each particle by processing the projected image of the particles obtained by using TEM with image processing software, and obtaining the average particle diameter as the number average of the equivalent circle diameters. .. The equivalent circle diameter, also called the Haywood diameter, is the diameter of a circle that has the same area as the projected image of the particles. In this method, the projected image is typically processed using image processing software created by the manufacturer and distributor of the TEM, which is provided with the TEM.

The surface-modified zirconia particles preferably have an average particle diameter of 2 to 100 nm, more preferably 3 to 50 nm, and even more preferably 5 to 20 nm. The average particle size of the surface-modified zirconia particles is a particle size (median diameter D ₅₀ ) at which the cumulative frequency distribution in the volume-based particle size distribution measurement by the dynamic light scattering method is 50%.

As the surface-modified zirconia particles, commercially available products or those surface-treated thereof can be used, and specific examples thereof include EP zirconium oxide, SPZ zirconium oxide, and UEP manufactured by Daiichi Rare Element Chemical Industry Co., Ltd. Zirconium oxide, SRP-2 zirconium oxide, UEP-100 zirconium oxide, PCS manufactured by Shin Nippon Denko Co., Ltd., N-PC, OGS, H4, Show Zirconia RZ (# 42 /) Solid particles such as 100, # 100/200, # 200F, # 280F, # 325F, # 3000F), PixClear (registered trademark) series manufactured by Pixelligent Technologies, Nissan Chemical Co., Ltd. Nanouse (registered trademark) ZR-40BL, Dispersed liquids of surface-modified zirconia particles such as ZR-30AL, ZSL-10A manufactured by Daiichi Rare Element Chemical Industry Co., Ltd., ZSL-10T, ZSL-20N, and ZSL00014, or surface-treated ones thereof. However, it is not limited to these. Further, the surface-modified zirconia particles may be produced by a known method.

The content of the surface-modified zirconia particles of the component (A) is usually about 1 to 98% by mass, preferably about 5 to 90% by mass, and more preferably about 10 to 80% by mass in the solid content. The solid content means a component other than the solvent among the components contained in the varnish.

In the present invention, as the charge-transporting organic compound, for example, those used in the field of organic EL and the like can be used. Specific examples thereof include arylamine derivatives (aniline derivatives) such as oligoaniline derivatives, N, N'-diarylbenzidine derivatives, N, N, N', N'-tetraarylbenzidine derivatives, oligothiophene derivatives, and thienothiophene derivatives. , Thionophen derivatives such as thienobenzothiophene derivatives, and various charge-transporting organic compounds such as pyrrole derivatives such as oligopyrrole. Of these, arylamine derivatives and thiophene derivatives are preferable.

Examples of the charge-transporting organic compound include JP-A-2002-151272, International Publication No. 2004/105446, International Publication No. 2005/043962, International Publication No. 2008/032617, International Publication No. 2008/032616, and International Publication No. 2013/0426223, International Publication 2014/141998, International Publication No. 2014/185208, International Publication No. 2015/050253, International Publication No. 2015/137391, International Publication No. 2015/137395, International Publication No. 2015 / 146912, International Publication No. 2015/146965, International Publication No. 2016/190326, International Publication No. 2016/136544, International Publication No. 2016/204079, etc. can be used.

In the present invention, the charge-transporting organic compound needs to be monodisperse (that is, the molecular weight distribution is 1). When an oligomer or polymer having a molecular weight distribution is used, the effect of suppressing the creep-up phenomenon becomes insufficient. The molecular weight of the charge-transporting organic compound is usually about 200 to 9,000 from the viewpoint of preparing a uniform varnish that gives a thin film having high flatness, but 300 from the viewpoint of obtaining a thin film having more excellent charge-transporting property. The above is preferable, 400 or more is more preferable, and from the viewpoint of preparing a uniform varnish that gives a thin film having high flatness with better reproducibility, 8,000 or less is preferable, 7,000 or less is more preferable, and 6,000 or less is preferable. Even more preferably, 5,000 or less is even more preferable.

As the charge transporting organic compound, a monodisperse charge transporting organic compound may be used alone, or two or more different monodisperse charge transporting organic compounds may be used in combination, but the creeping phenomenon From the viewpoint of suppressing reproducibility, the monodisperse charge-transporting organic compound used is preferably 1 to 3 types, and more preferably 1 or 2 types from the viewpoint of facilitating varnish preparation. More preferably, it is one kind.

Hereinafter, specific examples of charge-transporting organic compounds suitable in the present invention will be given, but the present invention is not limited thereto. In the following formula, Ph is a phenyl group and DPA is a diphenylamino group.

The content of the charge-transporting organic compound in the solid content is usually about 2 to 99% by mass, preferably about 10 to 95% by mass, and more preferably about 20 to 90% by mass.

[Organic solvent]
The organic solvent is not particularly limited as long as it can dissolve or disperse each of the above-mentioned components and each of the optional components described below, but it is preferable to use a low-polarity solvent in terms of excellent process compatibility. In the present invention, a low-polarity solvent is defined as a solvent having a relative permittivity of less than 7 at a frequency of 100 kHz, and a high-polarity solvent is defined as a solvent having a relative permittivity of 7 or more at a frequency of 100 kHz.

Examples of the low polar solvent include chlorine-based solvents such as chloroform and chlorobenzene; aromatic hydrocarbon-based solvents such as toluene, xylene, tetraline, cyclohexylbenzene and decylbenzene; 1-octanol, 1-nonanol, 1-decanol and the like. Alibo alcohol solvents; ethers such as tetrahydrofuran, dioxane, anisole, 4-methoxytoluene, 3-phenoxytoluene, dibenzyl ether, diethylene glycol dimethyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, etc. Solvents: Methyl benzoate, ethyl benzoate, butyl benzoate, isoamyl benzoate, bis (2-ethylhexyl) phthalate, dimethyl phthalate, diisopropyl malate, dibutyl maleate, dibutyl oxalate, hexyl acetate, propylene glycol monomethyl ether Examples thereof include ester solvents such as acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate.

Examples of the highly polar solvent include amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylisobutylamide, N-methylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone. System solvent: Ketone solvent such as ethyl methyl ketone, isophorone, cyclohexanone; Cyano solvent such as acetonitrile and 3-methoxypropionitrile; Ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,3-butanediol, Polyhydric alcohol solvents such as 2,3-butanediol; diethylene glycol monomethyl ether, diethylene glycol monophenyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, benzyl alcohol, 2-phenoxyethanol, 2-benzyl Monohydric alcohol solvents other than aliphatic alcohols such as oxyethanol, 3-phenoxybenzyl alcohol and tetrahydrofurfuryl alcohol; sulfoxide solvents such as dimethyl sulfoxide and the like can be mentioned.

The amount of the organic solvent used is such that the solid content concentration in the varnish of the present invention is usually about 0.1 to 20% by mass from the viewpoint of ensuring a sufficient film thickness while suppressing the precipitation of the charge-transporting organic compound. The amount is preferably 0.5 to 10% by mass. The organic solvent may be used alone or in combination of two or more.

The charge-transporting varnish of the present invention can also contain water as a solvent, but the water content is preferably higher than that of the solvent contained in the varnish from the viewpoint of obtaining an organic EL element having excellent durability with good reproducibility. From the viewpoint of obtaining a charge-transporting thin film having 3% by mass or less and suppressed pile-up with good reproducibility, it is preferable to use only an organic solvent as the solvent. In this case, "only the organic solvent" means that only the organic solvent is used as the solvent, and even the existence of "water" contained in a trace amount in the organic solvent used, the solid content, etc. is denied. It's not something to do.

[Dopant]
The charge-transporting varnish of the present invention may contain a dopant for the purpose of improving the charge-transporting property of the thin film obtained from the charge-transporting varnish of the present invention. The dopant is not particularly limited as long as it is soluble in at least one solvent used for varnish, and either an inorganic dopant or an organic dopant can be used. Further, in the process of obtaining a charge-transporting thin film which is a solid film from a varnish, the dopant first develops its function as a dopant by removing a part of the molecule due to an external stimulus such as heating during firing. It may be a substance that becomes improved, for example, an aryl sulfonic acid ester compound protected by a group in which a sulfonic acid group is easily eliminated.

Heteropolyacid is preferable as the inorganic dopant, and specific examples thereof include phosphomolybdic acid, silicate molybdic acid, phosphotungstic acid, phosphotungstic acid, and silicate tungstic acid.

The heteropolyacid has a structure in which a hetero atom is located at the center of a molecule, which is typically represented by a Keggin type chemical structure represented by the following formula (HPA1) or a Dawson type chemical structure represented by the following formula (HPA2). It is a polyacid formed by condensing isopolyacid, which is an oxygen acid such as vanadium (V), molybdenum (Mo), and tungsten (W), and oxygen acid of a different element. Examples of such dissimilar element oxygen acids include oxygen acids of silicon (Si), phosphorus (P), and arsenic (As).

Examples of the heteropolyacid include phosphomolybdic acid, silicate molybdic acid, phosphotungstic acid, silicate tungstic acid, and phosphotungstic acid. These may be used individually by 1 type or in combination of 2 or more type. The heteropolyacid used in the present invention is available as a commercially available product, and can also be synthesized by a known method. In particular, when one kind of heteropolyacid is used, phosphotungstic acid or phosphomolybdic acid is preferable as the one kind of heteropolyacid, and phosphotungstic acid is most suitable. When two or more kinds of heteropolyacids are used, one of the two or more kinds of heteropolyacids is preferably phosphotungstic acid or phosphomolybdic acid, and more preferably phosphotungstic acid.

In addition, in quantitative analysis such as elemental analysis, even if the number of elements of the heteropolyacid is large or small from the structure represented by the general formula, the heteropolyacid is obtained as a commercially available product or a known synthesis method. As long as it is properly synthesized according to the above, it can be used in the present invention.

That is, for example, phosphotungsic acid is generally represented by the chemical formulas H ₃ (PW ₁₂ O ₄₀ ) and nH ₂ O, and phosphomolybdic acid is generally represented by the chemical formulas H ₃ (PMo ₁₂ O ₄₀ ) and nH ₂ O. In the quantitative analysis, even if the number of P (phosphorus), O (oxygen) or W (tungsten) or Mo (molybdenum) in this formula is large or small, it is obtained as a commercial product, or As long as it is appropriately synthesized according to a known synthesis method, it can be used in the present invention. In this case, the mass of the heteropolyacid defined in the present invention is not the mass of pure phosphotungstic acid (phosphotungstic acid content) in the synthetic product or the commercially available product, but the form available as the commercially available product and the known synthesis. In a form that can be isolated by the method, it means the total mass in a state containing hydrated water and other impurities.

Examples of the organic dopant include aryl sulfonic acid, aryl sulfonic acid ester, an ionic compound composed of a predetermined anion and its counter cation, a tetracyanoquinodimethane derivative, a benzoquinone derivative and the like.

The aryl sulfonic acid compound is preferably represented by the following formula (A) or (B) from the viewpoint of the transparency of the thin film obtained from the charge transporting varnish of the present invention.

In the formula (A), A ¹ is -O- or -S-, but -O- is preferable. A ² is a naphthalene ring or an anthracene ring, but a naphthalene ring is preferable. A ³ is a 2- to tetravalent perfluorobiphenyl group. p ¹ is the number of bonds between A ¹ and A ^3, and is an integer satisfying 2 ≤ p ¹ ≤ 4, but A ³ is a divalent group derived from perfluorobiphenyl and p ¹ Is preferably 2. p ² is the number of sulfonic acid groups bonded to A ² , and is an integer satisfying 1 ≦ p ² ≦ 4, but 2 is preferable.

In the formula (B), A ⁴ to A ⁸ are independently hydrogen atom, halogen atom, cyano group, alkyl group having 1 to 20 carbon atoms, alkyl halide group having 1 to 20 carbon atoms or 2 to 2 carbon atoms, respectively. There are 20 halogenated alkenyl groups, but at least 3 of A ⁴ to A ⁸ are halogen atoms. q is the number of sulfonic acid groups bonded to the naphthalene ring and is an integer satisfying 1 ≦ q ≦ 4, but 2 to 4 is preferable, and 2 is more preferable.

Examples of the alkyl halide group having 1 to 20 carbon atoms include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, and a 3,3,3-trifluoropropyl group, 2,2, 3,3,3-Pentafluoropropyl group, perfluoropropyl group, 4,4,4-trifluorobutyl group, 3,3,4,4,4-pentafluorobutyl group, 2,2,3,3, Examples thereof include 4,4,4-heptafluorobutyl group and perfluorobutyl group. Examples of the halogenated alkenyl group having 2 to 20 carbon atoms include a perfluoroethenyl group, a 1-perfluoropropenyl group, a perfluoroallyl group, a perfluorobutenyl group and the like.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is preferable. The alkyl group having 1 to 20 carbon atoms include the same ones as mentioned in the description of R ^A and R ^B of formula (6).

Among these, A ⁴ to A ⁸ include a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an alkyl halide group having 1 to 10 carbon atoms, or an alkenyl halide having 2 to 10 carbon atoms. a group, and it is preferable that at least three fluorine atoms of a ⁴ - a ^8, a hydrogen atom, a fluorine atom, fluorinated cyano group, an alkyl group having 1 to 5 carbon atoms, 5 It is more preferably an alkyl group or a fluorinated alkenyl group having 2 to 5 carbon atoms, and at least 3 of A ⁴ to A ⁸ are fluorine atoms, and a hydrogen atom, a fluorine atom, a cyano group, and 1 to 1 carbon atoms. It is even more preferable that the perfluoroalkyl group of 5 or the perfluoroalkenyl group having 1 to 5 carbon atoms is, and A ⁴ , A ⁵ and A ⁸ are fluorine atoms. The perfluoroalkyl group is a group in which all the hydrogen atoms of the alkyl group are substituted with fluorine atoms, and the perfluoroalkyl group is a group in which all the hydrogen atoms of the alkenyl group are substituted with fluorine atoms.

Specific examples of suitable aryl sulfonic acids include, but are not limited to, those shown below.

As the aryl sulfonic acid ester compound, the aryl sulfonic acid ester compound disclosed in International Publication No. 2017/217455, International Publication No. 2017/217457, from the viewpoint of the transparency of the thin film obtained from the charge transport varnish of the present invention. Examples thereof include the aryl sulfonic acid ester compound disclosed in No. 2, the aryl sulfonic acid ester compound described in Japanese Patent Application No. 2017-243631 and the like.

Specifically, from the viewpoint of solubility in a low polar solvent, the aryl sulfonic acid ester compound is preferably represented by the following formulas (C) to (E).

In formula (C), A ¹¹ is an m-valent group derived from perfluorobiphenyl (ie, a group obtained by removing m fluorine atoms from perfluorobiphenyl). A ¹² is —O— or —S—, but —O— is preferred. A ¹³ is a (n + 1) -valent group derived from naphthalene or anthracene (that is, a group obtained by removing (n + 1) hydrogen atoms from naphthalene or anthracene), but a group derived from naphthalene is preferable. ..

In the formula (C), R ^s1 to R ^s4 are independently hydrogen atoms or linear or branched alkyl groups having 1 to 6 carbon atoms, and R ^s5 is ^optionally substituted carbon. It is a monovalent hydrocarbon group of numbers 2 to 20.

Examples of the linear or branched alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group and a tert-butyl group. , N-Hexyl group and the like. Of these, an alkyl group having 1 to 3 carbon atoms is preferable.

The monovalent hydrocarbon group having 2 to 20 carbon atoms may be linear, branched or cyclic, and specific examples thereof include ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl. Examples include an alkyl group such as a group, a sec-butyl group and a tert-butyl group; and an aryl group such as a phenyl group, a naphthyl group and a phenanthryl group.

Of R ^s1 to R ^s4 , it is preferable that R ^s1 or R ^s3 is a linear alkyl group having 1 to 3 carbon atoms and the rest are hydrogen atoms. Further, it is preferable that R ^s1 is a linear alkyl group having 1 to 3 carbon atoms and R ^s2 to R ^s4 are hydrogen atoms. As the linear alkyl group having 1 to 3 carbon atoms, a methyl group is preferable. Further, as R ^s5 , a linear alkyl group or a phenyl group having 2 to 4 carbon atoms is preferable.

In the formula (C), m is an integer satisfying 1 ≦ m ≦ 4, but 2 is preferable. n is an integer satisfying 1 ≦ n ≦ 4, but 2 is preferable.

In formula (D), A ¹⁴ is an m-valent hydrocarbon group having 6 to 20 carbon atoms containing one or more aromatic rings which may be substituted. The hydrocarbon group is a group obtained by removing m hydrogen atoms from a hydrocarbon having one or more aromatic rings and having 6 to 20 carbon atoms. Examples of the hydrocarbon include benzene, toluene, xylene, ethylbenzene, biphenyl, naphthalene, anthracene, phenanthrene and the like.

In addition, a part or all of the hydrogen atom of the hydrocarbon group may be further substituted with a substituent, and such substituents include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and a nitro. Group, cyano group, hydroxy group, amino group, silanol group, thiol group, carboxy group, sulfonic acid ester group, phosphoric acid group, phosphoric acid ester group, ester group, thioester group, amide group, monovalent hydrocarbon group, organo Examples thereof include an oxy group, an organoamino group, an organosilyl group, an organothio group, an acyl group and a sulfo group. Of these, as A ¹⁴ , a group derived from benzene, biphenyl, or the like is preferable.

In formula (D), A ¹⁵ is —O— or —S—, but —O— is preferred.

In formula (D), A ¹⁶ is a (n + 1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms. The aromatic hydrocarbon group is a group obtained by removing (n + 1) hydrogen atoms from the aromatic ring of an aromatic hydrocarbon compound having 6 to 20 carbon atoms. Examples of the aromatic hydrocarbon compound include benzene, toluene, xylene, biphenyl, naphthalene, anthracene, pyrene and the like. Of these, as A ¹⁶ , a group derived from naphthalene or anthracene is preferable, and a group derived from naphthalene is more preferable.

In formula (D), R ^s6 and R ^s7 are independently hydrogen atoms or linear or branched monovalent aliphatic hydrocarbon groups. R ^s8 is a linear or branched monovalent aliphatic hydrocarbon group. However, the total number of carbon atoms of R ^s6 , R ^s7 and R ^s8 is 6 or more. The upper limit of the total number of carbon atoms of R ^s6 , R ^s7 and R ^s8 is not particularly limited, but is preferably 20 or less, and more preferably 10 or less.

Specific examples of the linear or branched monovalent aliphatic hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group and tert-. Alkyl group having 1 to 20 carbon atoms such as butyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, decyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1- Examples thereof include an alkenyl group having 2 to 20 carbon atoms such as a methyl-2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group and a hexenyl group.

A hydrogen atom is preferable as R ^s6 , and an alkyl group having 1 to 6 carbon atoms is preferable as R ^s7 and R ^s8 . In this case, R ^s7 and R ^s8 may be the same or different.

In the formula (D), m is an integer satisfying 1 ≦ m ≦ 4, but 2 is preferable. n is an integer satisfying 1 ≦ n ≦ 4, but 2 is preferable.

In the formula (E), R ^s9 to R ^s13 independently represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. It is a halogenated alkenyl group having 2 to 10 carbon atoms.

The alkyl group having 1 to 10 carbon atoms may be linear, branched or cyclic, and specific examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl. Group, sec-butyl group, tert-butyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group and the like. Be done.

The alkyl halide group having 1 to 10 carbon atoms is not particularly limited as long as it is a group in which a part or all of the hydrogen atoms of the alkyl group having 1 to 10 carbon atoms are substituted with halogen atoms. The alkyl halide group may be linear, branched or cyclic, and specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, 1,1,2,2, 2-Pentafluoroethyl group, 3,3,3-trifluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,2,2,3,3,3-heptafluoropropyl Group, 4,4,4-trifluorobutyl group, 3,3,4,4,4-pentafluorobutyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, 1,1 , 2,2,3,3,4,4,4-nonafluorobutyl group and the like.

The halogenated alkenyl group having 2 to 10 carbon atoms is not particularly limited as long as it is a group in which a part or all of the hydrogen atoms of the alkenyl group having 2 to 10 carbon atoms are substituted with halogen atoms. Specific examples thereof include a perfluorovinyl group, a perfluoro-1-propenyl group, a perfluoro-2-propenyl group, a perfluoro-1-butenyl group, a perfluoro-2-butenyl group, and a perfluoro-3-butenyl group. And so on.

Of these, as R ^s9 , a nitro group, a cyano group, an alkyl halide group having 1 to 10 carbon atoms, an alkenyl halide group having 2 to 10 carbon atoms and the like are preferable, and a nitro group, a cyano group and 1 to 10 carbon atoms are preferable. The alkyl halide group of 4 and the alkenyl halide group having 2 to 4 carbon atoms are more preferable, and the nitro group, the cyano group, the trifluoromethyl group, the perfluoropropenyl group and the like are even more preferable. Further, as R ^s10 to R ^s13 , a halogen atom is preferable, and a fluorine atom is more preferable.

In formula (E), A ¹⁷ is —O—, —S— or —NH—, but —O— is preferred.

In formula (E), A ¹⁸ is a (n + 1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms. The aromatic hydrocarbon group is a group obtained by removing (n + 1) hydrogen atoms from the aromatic ring of an aromatic hydrocarbon compound having 6 to 20 carbon atoms. Examples of the aromatic hydrocarbon compound include benzene, toluene, xylene, biphenyl, naphthalene, anthracene, pyrene and the like. Of these, as A ¹⁸ , a group derived from naphthalene or anthracene is preferable, and a group derived from naphthalene is more preferable.

In the formula (E), R ^s14 to R ^s17 are independently hydrogen atoms or linear or branched monovalent aliphatic hydrocarbon groups having 1 to 20 carbon atoms. The monovalent aliphatic hydrocarbon group may be linear, branched or cyclic, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and an isobutyl group. , Se-butyl group, tert-butyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl Alkyl group having 1 to 20 carbon atoms such as group, n-dodecyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-methyl-2-propenyl group, 1-butenyl group, 2- Examples thereof include an alkenyl group having 2 to 20 carbon atoms such as a butenyl group, a 3-butenyl group and a hexenyl group. Of these, an alkyl group having 1 to 20 carbon atoms is preferable, an alkyl group having 1 to 10 carbon atoms is more preferable, and an alkyl group having 1 to 8 carbon atoms is even more preferable.

In formula (E), R ^s18 is a linear or branched monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or −OR ^s19 . R ^s19 is a monovalent hydrocarbon group having 2 to 20 carbon atoms which may be substituted.

^Examples of the linear or branched monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by R ^s18 include those similar to those described in the description of R ^s14 to R ^s17 . When R ^s18 is a monovalent aliphatic hydrocarbon group, R ^s18 is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and an alkyl group having 1 to 8 carbon atoms. Is even more preferable.

The monovalent hydrocarbon group having 2 to 20 carbon atoms represented by R ^s19 includes an aryl group such as a phenyl group, a naphthyl group and a phenanthryl group in addition to the above-mentioned monovalent aliphatic hydrocarbon groups other than the methyl group. And so on. Of these, as R ^s19 , a linear alkyl group or a phenyl group having 2 to 4 carbon atoms is preferable. Examples of the substituent that the monovalent hydrocarbon group may have include a fluorine atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group, and a cyano group.

In the formula (E), n is an integer satisfying 1 ≦ n ≦ 4, but 2 is preferable.

Specific examples of suitable aryl sulfonic acid ester compounds include, but are not limited to, those shown below.

As the ionic compound composed of the predetermined anion and its counter cation, the ionic compound represented by the following formula (F) is preferable from the viewpoint of the transparency of the thin film obtained from the charge transporting varnish of the present invention.

In the formula (F), E is a Group 13 element of the long periodic table, and Ar ¹ to Ar ⁴ are independently aryl groups having 6 to 20 carbon atoms or heteroaryl groups having 2 to 20 carbon atoms. A group, such as a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom, an acyl group having 2 to 12 carbon atoms such as a cyano group, a nitro group or an acetyl group, or a halogen having 1 to 10 carbon atoms such as a trifluoromethyl group. It may be substituted with an alkylated group.

As the Group 13 element, a boron atom, an aluminum atom, and a gallium atom are preferable, and a boron atom is more preferable. Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-phenanthryl group and a 2-phenanthryl group. Examples thereof include a 3-phenanthryl group, a 4-phenanthryl group, and a 9-phenanthryl group. Examples of the heteroaryl group having 2 to 20 carbon atoms include 2-thienyl group, 3-thienyl group, 2-furanyl group, 3-furanyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group and 3-. Isooxazolyl group, 4-isoxazolyl group, 5-isooxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 2-imidazolyl group, 4- Examples thereof include an imidazolyl group, a 2-pyridyl group, a 3-pyridyl group, and a 4-pyridyl group.

In formula (F), M ⁺ is an onium ion. Examples of the onium ion include iodonium ion, sulfonium ion, ammonium ion, phosphonium ion and the like, and iodonium ion represented by the following formula (G) is particularly preferable.

In formula (G), R ¹ and R ² independently have an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, and 6 to 20 carbon atoms, respectively. Aryl group or heteroaryl group having 2 to 20 carbon atoms, halogen atom, cyano group, nitro group, alkyl group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, alkynyl group having 2 to 12 carbon atoms. , It may be substituted with an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 2 to 20 carbon atoms.

Examples of the tetracyanoquinodimethane derivative include 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2-fluoro-7,7,8,8-tetracyanoquinodimethane, 2,5-difluoro. -7,7,8,8-Tetracyanoquinodimethane, Tetrafluoro-7,7,8,8-Tetracyanoquinodimethane (F4TCNQ), Tetrachloro-7,7,8,8-Tetracyanoquinodimethane Methane, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, 2-chloro-7,7,8,8-tetracyanoquinodimethane, 2,5-difluoro-7,7,8, Examples thereof include 8-tetracyanoquinodimethane, 2,5-dichloro-7,7,8,8-tetracyanoquinodimethane.

Examples of the benzoquinone derivative include tetrachloro-1,4-benzoquinone (chloranil), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and the like.

Of these dopants, aryl sulfonic acid compounds and aryl sulfonic acid ester compounds are preferable because they have a large effect of suppressing the creep-up phenomenon.

When the charge-transporting varnish of the present invention contains a dopant, the content thereof varies depending on the type of dopant, the desired charge-transporting property, and the like, and therefore cannot be unconditionally defined. However, the dopant for the charge-transporting organic compound (H) (H) The content ratio (D / H) of D) is usually about 0.01 to 50 in terms of molar ratio, preferably about 0.1 to 10, and more preferably 1. The amount is about 0 to 5.0.

[Other ingredients]
The charge-transporting varnish of the present invention may further contain an organic silane compound for the purpose of adjusting the film physical characteristics of the obtained charge-transporting thin film. Examples of the organic silane compound include a dialkoxysilane compound, a trialkoxysilane compound, and a tetraalkoxysilane compound. In particular, as the organic silane compound, a dialkoxysilane compound or a trialkoxysilane compound is preferable, and a trialkoxysilane compound is more preferable. The organic silane compound may be used alone or in combination of two or more.

When the varnish of the present invention contains an organic silane compound, the content thereof is usually about 0.1 to 50% by mass in the solid content, but the flatness of the obtained thin film is improved and the decrease in charge transportability is suppressed. In consideration of such a balance, it is preferably about 0.5 to 40% by mass, more preferably about 0.8 to 30% by mass, and even more preferably about 1 to 20% by mass.

The charge-transporting varnish of the present invention may contain an amine compound from the viewpoint of dissolving a charge-transporting organic compound or a dopant in an organic solvent to obtain a highly uniform varnish, and the content thereof is usually in the solid content. It is about 0.1 to 50% by mass.

The method for preparing the charge-transporting varnish is not particularly limited, and examples thereof include a method of adding a charge-transporting organic compound, surface-modified zirconia particles, and if necessary, a dopant or the like to the organic solvent in any order or at the same time. When there are a plurality of organic solvents, a charge-transporting organic compound, surface-modified zirconia particles, and if necessary, a dopant or the like may be dissolved or dispersed in one organic solvent, and another organic solvent may be added thereto. Often, a charge-transporting organic compound, surface-modified zirconia particles, and, if necessary, a dopant and the like may be dissolved or dispersed sequentially or simultaneously in a mixed solvent of a plurality of organic solvents.

Further, in the present invention, a charge transporting varnish may be prepared using a dispersion of surface-modified zirconia particles. In this case as well, the mixing order is not particularly limited, but a mixture is prepared by mixing components other than the surface-modified zirconia particles (charge-transporting organic compound, etc.) with an organic solvent, and the surface-modified zirconia particles prepared in advance in the mixture are prepared. Examples thereof include a method of adding a dispersion and a method of adding a mixture thereof to a prepared dispersion of surface-modified zirconia particles. At this time, if necessary, an additional organic solvent may be added at the end, or a part of the components relatively easily soluble in the organic solvent may be added at the end without being included in the mixture. From the viewpoint of suppressing aggregation and separation of constituents and preparing varnish with excellent uniformity with good reproducibility, a dispersion containing surface-modified zirconia particles in a good dispersed state or a good dissolved state and a mixture containing other components are prepared. It is preferable to prepare separately, mix the two, and then stir well. It should be noted that surface-modified zirconia particles, charge-transporting organic compounds, etc. may aggregate or precipitate when mixed depending on the type and amount of the organic solvent mixed together. When preparing a varnish using a dispersion, it is necessary to determine the concentration of the dispersion and the amount to be used so that the surface-modified zirconia particles in the finally obtained charge-transporting varnish have a desired amount. Also note the point. When preparing the charge transporting varnish, it may be appropriately heated as long as the components do not decompose or deteriorate.

The charge-transporting varnish of the present invention is a submicrometer-order filter after dissolving a charge-transporting organic compound and, if necessary, a dopant or the like in an organic solvent from the viewpoint of obtaining a thin film having higher flatness with good reproducibility. It is desirable to filter using such as.

The viscosity of the charge-transporting varnish of the present invention is usually 1 to 50 mPa · s at 25 ° C. The surface tension of the charge-transporting varnish of the present invention is usually 20 to 50 mN / m at 25 ° C. The viscosity is a value measured by a TVE-25 type viscometer manufactured by Toki Sangyo Co., Ltd. The surface tension is a value measured by an automatic surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. The viscosity and surface tension of the varnish can be adjusted by changing the types of solvents described above, their ratios, the solid content concentration, and the like in consideration of various factors such as a desired film thickness.

From the viewpoint of obtaining a charge-transporting thin film having excellent flatness with good reproducibility, and from the viewpoint of obtaining a charge-transporting thin film having uniform optical characteristics with good reproducibility, the charge-transporting organic substance monodisperse in the charge-transporting varnish of the present invention. The compound and, if contained, the dopant and the like are uniformly dissolved in the organic solvent, and the zirconia particles surface-modified with the surface treatment agent are uniformly dispersed in the organic solvent.

[Charge transport thin film]
The charge-transporting thin film of the present invention can be formed by applying the charge-transporting varnish of the present invention on a substrate and firing it.

Examples of the varnish coating method include, but are not limited to, the dip method, spin coating method, transfer printing method, roll coating method, brush coating, inkjet method, spray method, slit coating method, and the like. It is preferable to adjust the viscosity and surface tension of the varnish according to the coating method.

Further, the firing atmosphere of the charge-transporting varnish after coating is not particularly limited, and it is possible to obtain a thin film having a uniform film-forming surface and high charge-transporting property not only in the air atmosphere but also in an inert gas such as nitrogen or in a vacuum. it can. Depending on the type of dopant used together, a thin film having higher charge transportability may be obtained with good reproducibility by firing the varnish in an air atmosphere.

The firing temperature is usually set appropriately within the range of about 100 to 260 ° C. in consideration of the intended use of the obtained thin film, the degree of charge transportability applied to the obtained thin film, the type of solvent, the boiling point, and the like. At the time of firing, a temperature change of two or more steps may be applied for the purpose of exhibiting higher uniform film forming property or allowing the reaction to proceed on the substrate, and heating may be performed by, for example, a hot plate or the like. It may be carried out using an appropriate device such as an oven.

The thickness of the charge transporting thin film is not particularly limited, but when used as a functional layer between the anode and the light emitting layer such as a hole injection layer, a hole transport layer, or a hole injection transport layer of an organic EL element, 5 The lower limit is preferably 10 nm, more preferably 20 nm, still more preferably 30 nm, still more preferably 40 nm, and even more preferably, from the viewpoint of obtaining a charge-transporting thin film having excellent flatness with good reproducibility. Is 45 nm, and the upper limit thereof is preferably 250 nm, more preferably 200 nm, even more preferably 150 nm, still more preferably 100 nm, and even more preferably 75 nm from the viewpoint of obtaining a thin film having excellent transparency with good reproducibility. .. If the particle size of the surface-modified zirconia particles is larger than the film thickness, a thin film having excellent flatness cannot be obtained. Therefore, the particle size of the surface-modified zirconia particles to be used is determined in consideration of the desired film thickness. Usually, the average particle diameter (nm) of the surface-modified zirconia particles is 3 nm or more smaller than the thickness (nm) of the charge-transporting thin film. Examples of the method of changing the film thickness include a method of changing the solid content concentration in the varnish and a method of changing the amount of liquid on the substrate at the time of coating.

The charge-transporting thin film of the present invention exhibits a refractive index (n) of 1.67 or more and an extinction coefficient (k) of 0.040 or less on average in the wavelength region of 400 to 800 nm, but in some embodiments. It exhibits a refractive index of 1.69 or higher, in some other embodiments a refractive index of 1.72 or higher, and in yet another embodiment a refractive index of 1.73 or higher. Further, in one embodiment, the extinction coefficient is 0.030 or less, in another aspect, the extinction coefficient is 0.025 or less, and in yet another aspect, the extinction coefficient is 0.020 or less.

The charge-transporting thin film of the present invention can be formed by the method described above, but by using the charge-transporting varnish of the present invention, the charge-transporting thin film can be suitably formed in the partition wall of the substrate with a partition wall.

The substrate with a partition wall is not particularly limited as long as it is a substrate on which a predetermined pattern is formed by a known photolithography method or the like. Normally, there are a plurality of openings defined by the partition wall on the substrate. Usually, the size of the opening is 100 to 210 μm on the long side, 40 μm × 100 μm on the short side, and the bank taper angle is 20 to 80 °. The material of the substrate is not particularly limited, but is a transparent electrode material typified by indium tin oxide (ITO) and indium zinc oxide (IZO) used as an anode material of an electronic element; aluminum, gold, Metal anode materials composed of metals typified by silver, copper, indium, etc. or alloys thereof; polymer anode materials such as polythiophene derivatives and polyaniline derivatives having high charge transport properties, etc., are subjected to flattening treatment. Is preferable.

The charge transporting varnish of the present invention is applied to the inside of the partition wall of the substrate with a partition wall by an inkjet method, then depressurized, and further heated if necessary to remove the solvent from the charge transporting varnish coated inside the partition wall. A charge-transporting thin film can be produced to produce a substrate with a charge-transporting thin film, and further, by laminating other functional films on the charge-transporting thin film, an electronic element such as an organic EL element can be formed. Can be manufactured. At this time, the atmosphere at the time of coating with the inkjet is not particularly limited, and may be any of an air atmosphere, an atmosphere of an inert gas such as nitrogen, and a reduced pressure.

The degree of decompression (vacuum degree) at the time of depressurization is not particularly limited as long as the solvent of the varnish evaporates, but is usually 1,000 Pa or less, preferably 100 Pa or less, more preferably 50 Pa or less, still more preferably 25 Pa or less, and further. It is preferably 10 Pa or less. The depressurizing time is also not particularly limited as long as the solvent evaporates, but is usually about 0.1 to 60 minutes, preferably about 1 to 30 minutes. The conditions for firing (heating) are the same as the above-mentioned conditions.

According to the method described above, the creeping up of the varnish can be effectively suppressed in the partition wall. Specifically, the pile-up index described later is usually a high value of 84% or more, preferably 87% or more, more preferably 90% or more, even more preferably 93% or more, still more preferably 96% or more, and pile. Up can be suppressed. The pile-up index is when the partition wall (bank) width is A (μm) and the film thickness range of + 10% from the film thickness of the charge-transporting thin film at the center of the partition wall (bank) is B (μm). It can be derived from the formula (B / A) × 100 (%).

[Organic EL element]
The organic EL device of the present invention has a pair of electrodes, and has a functional layer made of the charge-transporting thin film of the present invention between these electrodes.

Typical configurations of the organic EL element include, but are not limited to, the following (a) to (f). In the following configuration, if necessary, an electron block layer or the like may be provided between the light emitting layer and the anode, and a hole block layer or the like may be provided between the light emitting layer and the cathode. Further, the hole injection layer, the hole transport layer or the hole injection transport layer may have a function as an electron block layer or the like, and the electron injection layer, the electron transport layer or the electron injection transport layer may serve as a hole block layer or the like. It may also have the functions of. Further, if necessary, an arbitrary functional layer can be provided between the layers.
(A) Electron / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (b) anode / hole injection layer / hole transport layer / light emitting layer / electron injection transport layer / Cathode (c) anode / hole injection transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (d) anode / hole injection transport layer / light emitting layer / electron injection transport layer / cathode (e) anode / positive Hole injection layer / hole transport layer / light emitting layer / cathode (f) Electron / hole injection transport layer / light emitting layer / cathode

The "hole injection layer", "hole transport layer" and "hole injection transport layer" are layers formed between the light emitting layer and the anode, and transport holes from the anode to the light emitting layer. It has a function. When only one layer of hole transporting material is provided between the light emitting layer and the anode, it is a "hole injection transport layer", and a layer of hole transporting material between the light emitting layer and the anode. When two or more layers are provided, the layer close to the anode is the "hole injection layer", and the other layers are the "hole transport layers". In particular, as the hole injection (transport) layer, a thin film having excellent not only hole acceptability from the anode but also hole injection property into the hole transport (emission) layer is used.

The "electron injection layer", "electron transport layer" and "electron transport layer" are layers formed between the light emitting layer and the cathode and have a function of transporting electrons from the cathode to the light emitting layer. Is. When only one layer of electron transporting material is provided between the light emitting layer and the cathode, it is an "electron injection transporting layer", and two layers of electron transporting material are provided between the light emitting layer and the cathode. When the above is provided, the layer close to the cathode is the "electron injection layer", and the other layers are the "electron transport layer".

The "light emitting layer" is an organic layer having a light emitting function, and includes a host material and a dopant material when a doping system is adopted. At this time, the host material mainly has a function of promoting the recombination of electrons and holes and confining the excitons in the light emitting layer, and the dopant material efficiently emits excitons obtained by the recombination. Has a function. In the case of a phosphorescent device, the host material mainly has a function of confining excitons generated by the dopant in the light emitting layer.

The charge transporting thin film of the present invention can be suitably used as a functional layer provided between the anode and the light emitting layer in an organic EL device, and can be used as a hole injection layer, a hole transport layer, or a hole injection transport layer. It can be used more preferably, and can be used even more preferably as a hole injection layer.

The materials and manufacturing methods used when manufacturing an organic EL device using the charge transporting varnish of the present invention include, but are not limited to, the following.

An example of a method for producing an organic EL device having a hole injection layer made of a charge transporting thin film obtained from the charge transporting varnish of the present invention is as follows. It is preferable that the electrode is preliminarily subjected to surface treatment such as cleaning with alcohol, pure water or the like, UV ozone treatment, oxygen-plasma treatment or the like within a range that does not adversely affect the electrode.

A hole injection layer is formed on the anode substrate by the above method using the charge transporting varnish of the present invention. This is introduced into a vacuum vapor deposition apparatus, and a hole transport layer, a light emitting layer, an electron transport layer / hole block layer, an electron injection layer, and a cathode metal are sequentially vapor-deposited. Alternatively, instead of forming the hole transport layer and the light emitting layer by vapor deposition in the method, a composition for forming a hole transport layer containing a hole transport polymer and a composition for forming a light emitting layer containing a light emitting polymer are used. These layers are formed by a wet process using. If necessary, an electron block layer may be provided between the light emitting layer and the hole transport layer.

Examples of the anode material include transparent electrodes typified by ITO and IZO, metals typified by aluminum, and metal anodes composed of alloys thereof, and those subjected to flattening treatment are preferable. Polythiophene derivatives and polyaniline derivatives having high charge transport properties can also be used. Examples of other metals constituting the metal anode include, but are not limited to, gold, silver, copper, indium, and alloys thereof.

Examples of the material for forming the hole transport layer include (triphenylamine) dimer derivative, [(triphenylamine) dimer] spirodimer, and N, N'-bis (naphthalen-1-yl) -N, N'-. Bis (phenyl) -benzidine (α-NPD), 4,4', 4''-tris [3-methylphenyl (phenyl) amino] triphenylamine (m-MTDATA), 4,4', 4''- Triarylamines such as tris [1-naphthyl (phenyl) amino] triphenylamine (1-TNATA), 5,5''-bis- {4- [bis (4-methylphenyl) amino] phenyl} -2 , 2': 5', 2''-oligothiophenes such as turthiophene (BMA-3T) and the like can be mentioned.

Examples of the material forming the light emitting layer include a metal complex such as an aluminum complex of 8-hydroxyquinoline, a metal complex of 10-hydroxybenzo [h] quinoline, a bisstyrylbenzene derivative, a bisstyryl arylene derivative, and (2-hydroxyphenyl). Low molecular weight luminescent materials such as benzothiazole metal complexes and silol derivatives; poly (p-phenylene vinylene), poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene], poly (3- Alkylthiophene), a system in which a light emitting material and an electron transfer material are mixed with a polymer compound such as polyvinylcarbazole, and the like, but are not limited thereto.

When the light emitting layer is formed by vapor deposition, it may be co-deposited with a light emitting dopant, and the light emitting dopant may be a metal such as tris (2-phenylpyridine) iridium (III) (Ir (ppy) ₃ ). Examples thereof include, but are not limited to, a complex, a naphthacene derivative such as rubrene, a quinacridone derivative, and a condensed polycyclic aromatic ring such as perylene.

Examples of the material for forming the electron transport layer / whole block layer include, but are not limited to, an oxydiazole derivative, a triazole derivative, a phenanthroline derivative, a phenylquinoxaline derivative, a benzimidazole derivative, and a pyrimidine derivative.

Examples of the material forming the electron injection layer include metal oxides such as lithium oxide (Li ₂ O), magnesium oxide (Mg O), and alumina (Al ₂ O ₃ ), lithium fluoride (LiF), and sodium fluoride (NaF). ), But is not limited to these.

Examples of the cathode material include, but are not limited to, aluminum, magnesium-silver alloy, aluminum-lithium alloy, and the like.

Examples of the material for forming the electron block layer include, but are not limited to, tris (phenylpyrazole) iridium and the like.

Examples of the hole-transporting polymer include poly [(9,9-dihexylfluorenyl-2,7-diyl) -co- (N, N'-bis {p-butylphenyl} -1,4-diamino). Phenylene)], poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (N, N'-bis {p-butylphenyl} -1,1'-biphenylene-4,4- Diamine)], poly [(9,9-bis {1'-penten-5'-yl} fluorenyl-2,7-diyl) -co- (N, N'-bis {p-butylphenyl} -1, 4-Diaminophenylene)], poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) -benzidine] -endcapped with polysilsesquioxane, poly [(9,, 9-didioctylfluorenyl-2,7-diyl) -co- (4,4'-(N- (p-butylphenyl)) diphenylamine)] and the like can be mentioned.

Examples of the luminescent polymer include polyfluorene derivatives such as poly (9,9-dialkylfluorene) (PDAF) and poly (2-methoxy-5- (2'-ethylhexoxy) -1,4-phenylene vinylene) (MEH). -PPV) and other polyphenylene vinylene derivatives, poly (3-alkylthiophene) (PAT) and other polythiophene derivatives, polyvinylcarbazole (PVCz) and the like can be mentioned.

The materials forming the anode and cathode and the layer formed between them differ depending on whether the element having the bottom emission structure or the top emission structure is manufactured. Therefore, the material is appropriately selected in consideration of this point. ..

Normally, in an element having a bottom emission structure, a transparent anode is used on the substrate side to extract light from the substrate side, whereas in an element having a top emission structure, a reflective anode made of metal is used and the direction is opposite to that of the substrate. Light is extracted from a certain transparent electrode (cathode) side. Therefore, for example, regarding the anode material, a transparent anode such as ITO is used when manufacturing an element having a bottom emission structure, and a reflective anode such as Al / Nd is used when manufacturing an element having a top emission structure.

The organic EL device of the present invention may be sealed together with a water catching agent or the like, if necessary, in accordance with a conventional method in order to prevent deterioration of characteristics.

As described above, the charge transporting thin film of the present invention can be used as a functional layer of an organic EL element, but in addition, an organic photoelectric conversion element, an organic thin film solar cell, an organic perovskite photoelectric conversion element, an organic integrated circuit, and an organic Electric field effect transistors, organic thin films, organic light emitting transistors, organic optical testers, organic photoreceivers, organic electric field extinguishing devices, light emitting electronic chemical batteries, quantum dot light emitting diodes, quantum lasers, organic laser diodes, organic Plasmon light emitting devices, etc. It can also be used as a functional layer of an electronic device.

Hereinafter, the present invention will be described in more detail with reference to synthetic examples, production examples, examples and comparative examples, but the present invention is not limited to the following examples.

The equipment used is as follows.
(1) MALDI-TOF-MS: Bruker's autoflex III smart beam
(2) ^{1 1} H-NMR: JNM-ECP300 FT NMR SYSTEM manufactured by JEOL Ltd.
(3) Substrate cleaning: Substrate cleaning equipment manufactured by Choshu Sangyo Co., Ltd. (decompression plasma method)
(4) Varnish application: Spin coater MS-A100 manufactured by Mikasa Co., Ltd.
(5) Film thickness measurement and surface shape measurement: Fine shape measuring machine surf coder ET-4000A manufactured by Kosaka Laboratory Co., Ltd.
(6) Manufacture of element: Multi-function vapor deposition equipment system C-E2L1G1-N manufactured by Choshu Sangyo Co., Ltd.
(7) Measurement of element current density: Multi-channel IVL measuring device manufactured by EHC Co., Ltd. (8) Measurement of refractive index (n): Multi-entry angle spectroscopic ellipsometer VASE manufactured by JA Woolam Co., Ltd.
(9) Measurement of extinction coefficient (k): Multi-entry angle spectroscopic ellipsometer VASE manufactured by JA Woolam
(10) Inkjet device: Dedicated driver WAVE BUILDER (model number: PIJD-1) manufactured by Cluster Technology Co., Ltd., observation device with camera inkjetlado, automatic stage Inkjet Designer and inkjet head PIJ-25NSET

The reagents used are as follows.
MMA: Methyl methacrylate HEMA: 2-Hydroxyethyl methacrylate HPMA: 4-Hydroxyphenyl methacrylate HPMA-QD: Condensation reaction of 1 mol of 4-hydroxyphenyl methacrylate with 1.1 mol of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride Compound CHMI: N-cyclohexylmaleimide PFHMA: 2- (perfluorohexyl) ethyl methacrylate MAA: AIBN methacrylate: α, α'-azobisisobutyronitrile QD1: α, α, α'-tris (4) -Hydroxyphenyl) A compound synthesized by a condensation reaction of 1 mol of -1-ethyl-4-isopropylbenzene and 1.5 mol of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride. GT-401: Tetrabutanetetracarboxylate (Tetrabutantetracarboxylate) 3,4-Epoxycyclohexylmethyl) modified ε-caprolactone (trade name: Epolide GT-401, manufactured by Daicel Co., Ltd.)
PGME: Propylene glycol monomethyl ether PGMEA: Propylene glycol monomethyl ether acetate CHN: Cyclohexanone TMAH: Tetramethylammonium hydroxide TBSCl: tert-butyldimethylchlorosilane THF: tetrahydrofuran
Pd (dba) ₂ : Bis (dibenzylideneacetone) Palladium (0)
[(t-Bu) ₃ PH] BF ₄ : Tritert-butylphosphnium tetrafluoroborate
t-BuONa: tert-sodium butoxy TBAF: tetrabutylammonium fluoride

[1] Preparation of substrate with partition wall (bank) (1) Synthesis of acrylic polymer [Synthesis Example 1-1]
MMA (10.0 g), HEMA (12.5 g), CHMI (20.0 g), HPMA (2.50 g), MAA (5.00 g) and AIBN (3.20 g) are dissolved in PGME (79.8 g). Then, the reaction was carried out at 60 to 100 ° C. for 20 hours to obtain an acrylic polymer P1 solution (solid content concentration: 40% by mass). The Mn of the acrylic polymer P1 was 3,700 and the Mw was 6,100.

[Synthesis Example 1-2]
HPMA-QD (2.50 g), PFHMA (7.84 g), MAA (0.70 g), CHMI (1.46 g) and AIBN (0.33 g) were dissolved in CHN (51.3 g) and heated to 110 ° C. The mixture was stirred for 20 hours and reacted to obtain an acrylic polymer P2 solution (solid content concentration: 20% by mass). The Mn of the acrylic polymer P2 was 4,300 and the Mw was 6,300.

The number average molecular weight (Mn) and weight average molecular weight (Mw) of the acrylic polymers P1 and P2 were measured by gel permeation chromatography (GPC) under the following conditions.
・ Chromatograph: GPC device LC-20AD manufactured by Shimadzu Corporation
-Column: Shodex KF-804L and 803L (manufactured by Showa Denko KK) and TSK-GEL (manufactured by Tosoh Corporation) are connected in series.-Column temperature: 40 ° C
-Detector: UV detector (254 nm) and RI detector-Eluent: tetrahydrofuran-Column flow rate: 1 mL / min

(2) Production of Positive Photosensitive Resin Composition [Production Example 1]
Acrylic polymer P1 solution (5.04 g), acrylic polymer P2 solution (0.05 g), QD1 (0.40 g), GT-401 (0.09 g) and PGMEA (6.42 g) are mixed and at room temperature. The mixture was stirred for 3 hours to obtain a uniform solution to obtain a positive photosensitive resin composition.

(3) Fabrication of Substrate with Partition (Bank) [Manufacturing Example 2]
The positive photosensitive resin composition obtained in Production Example 1 was applied to an ITO-glass substrate that had been ozone-cleaned for 10 minutes using UV-312 manufactured by Technovision Co., Ltd. using a spin coater, and then the substrate. Was prebaked (100 ° C., 120 seconds) on a hot plate to form a thin film having a film thickness of 1.2 μm. At 175 mJ / cm ² using ultraviolet rays with a wavelength of 365 nm by the ultraviolet irradiation device PLA-600FA manufactured by Canon Inc. through a mask with a pattern in which a large number of rectangles with a long side of 200 μm and a short side of 100 μm are drawn on this thin film. Exposed. Then, the thin film was immersed in a 1.0 mass% TMAH aqueous solution for 120 seconds for development, and then the thin film was washed with running water for 20 seconds using ultrapure water. Next, the thin film on which this rectangular pattern was formed was post-baked (230 ° C., 30 minutes) and cured to prepare a substrate with a partition wall.

[2] Synthesis of charge-transporting organic compound [Synthesis example 2] Synthesis of aniline derivative A (1) Synthesis of intermediate 1

A THF solution (200 mL) of 2-bromocarbazole (24.6 g, 100 mmol) was added dropwise to a THF suspension (150 mL) of 60% sodium hydride (4.8 g, 120 mmol) under ice-cooling, and then at room temperature. The mixture was stirred for 30 minutes. A THF solution (40 mL) of TBSCl (18.1 g, 120 mmol) was added dropwise under ice-cooling, and the mixture was stirred at room temperature for 2 hours. After adding water (66 mL) and extracting with ethyl acetate (50 mL) three times, the obtained organic layer was dried over magnesium sulfate, magnesium sulfate was removed by filtration, the solvent was distilled off from the obtained filtrate, and the mixture was light brown. Obtained a solid. Hexane (150 mL) was added to the obtained light brown solid and filtered. Methanol (333 mL) was added to the filter, and the mixture was refluxed for 30 minutes, cooled to room temperature, filtered, and the filter was recovered to obtain Intermediate 1 as a white solid (yield 27.1 g, yield). 75%). ¹ The measurement results of ¹ H-NMR are shown below.
^{1 1} H-NMR (500MHz, CDCl ₃ ) δ [ppm]: 0.75 (s, 6H), 1.04 (s, 9H), 7.24 (t, J = 7.5Hz, 1H), 7.34 (d, J = 8.0Hz, 1H), 7.38 (t, J = 7.5Hz, 1H), 7.59 (d, J = 8.5Hz, 1H), 7.73 (s, 1H), 7.90 (d, J = 8.5Hz, 1H), 8.02 (d, J = 7.5Hz, 1H).

(2) Synthesis of intermediate 2

Pd (dba) ₂ (173 mg, 0.3 mmol), [(t-t-) in a toluene solution (60 mL) of 4,4'-diaminodiphenylamine (3 g, 15 mmol) and intermediate 1 (11.1 g, 30.75 mmol). Bu) ₃ PH] BF ₄ (174 mg, 0.6 mmol) and t-BuONa (3.17 g, 33 mmol) were added, and the mixture was heated and stirred at 80 ° C. for 2 hours. After washing with saturated brine (60 mL), the obtained organic layer is dried over sodium sulfate, sodium sulfate is removed by filtration, the solvent is distilled off from the obtained filtrate, and the mixture is purified by column chromatography. Body 2 was obtained as a white solid (yield 3.6 g, yield 32%). ¹ The measurement results of ¹ H-NMR are shown below.
^{1 1} H-NMR (500MHz, DMSO-d ₆ ) δ [ppm]: 0.67 (s, 12H), 0.96 (s, 18H), 6.85 (d, J = 8.5Hz, 2H), 7.02 (d, J = 8.5) Hz, 4H), 7.08 (d, J = 8.5Hz, 4H), 7.11 (t, J = 7.5Hz, 2H), 7.18-7.22 (m, 4H), 7.53 (d, J = 8.0Hz, 2H), 7.76 (brs, 1H), 7.87 (d, J = 8.5Hz, 2H), 7.90 (d, J = 7.5Hz, 2H), 7.96 (brs, 2H).

(3) Synthesis of intermediate 3

Pd (dba) ₂ (155 mg, 0.27 mmol) in a toluene solution (35 mL) of Intermediate 2 (3.45 g, 4.56 mmol) and 2-bromo-9-phenylcarbazole (4.63 g, 14.36 mmol). , [(T-Bu) ₃ PH] BF ₄ (160 mg, 0.55 mmol) and t-BuONa (1.84 g, 19.15 mmol) were added, and the mixture was heated and stirred at 90 ° C. for 2 hours. The obtained reaction mixture was washed with saturated brine (35 mL), and the organic layer was purified by silica gel column (90 g, eluent: toluene). The obtained solution was concentrated to 140 g, added dropwise to a mixed solution of ethyl acetate (260 mL) / methanol (780 mL), and stirred at room temperature for 2 hours. The precipitated solid was filtered to give Intermediate 3 as a yellow solid (5.35 g, yield: 79%). ¹ The measurement results of ¹ H-NMR are shown below.
¹ H-NMR (500MHz, THF-d ₈ ) δ [ppm]: 0.50 (s, 12H), 0.86 (s, 18H), 7.03-7.08 (m, 15H), 7.11-7.21 (m, 8H), 7.26 -7.34 (m, 10H), 7.42-7.58 (m, 15H), 7.88 (d, J = 8.5Hz, 2H), 7.92 (d, J = 7.5Hz, 2H), 8.00-8.06 (m, 6H).

(4) Synthesis of aniline derivative A

A 1 mol / L TBAF THF solution (10.7 mL, 10.7 mmol) was added dropwise to a THF solution (25 mL) of Intermediate 3 (5.28 g, 3.56 mmol) under ice-cooling, and the mixture was stirred at room temperature for 2 hours. did. The reaction solution was added dropwise to methanol (90 mL), and the precipitated solid was filtered to obtain an aniline derivative A as a yellow solid (yield 4.16 g, yield 93%). ¹ The measurement results of ¹ H-NMR and MALDI-TOF-MS are shown below.
¹ H-NMR (500MHz, THF-d ₈ ) δ [ppm]: 6.96-7.12 (m, 17H), 7.17-7.35 (m, 18H), 7.41-7.60 (m, 13H), 7.89-7.94 (m, 4H), 7.99-8.05 (m, 6H), 10.00 (brs, 2H).
MALDI-TOF-MS m / Z found: 1253.52 ([M + H] ⁺ calcd: 1253.49)

[3] Synthesis of dopant [Synthesis Example 3] Synthesis of aryl sulfonic acid ester C Aryl sulfonic acid ester C represented by the following formula was synthesized according to the method described in International Publication No. 2017/217455.

[4] Preparation of charge-transporting varnish [Example 1]
A mixture of 0.117 g of the aniline derivative A and 0.233 g of the aryl sulfonic acid ester C (D / H = 2.0 (molar ratio)), 5.425 g of triethylene glycol butyl methyl ether, 3.022 g of diisopropyl malonic acid and dimethyl phthalate. 2.170 g was added and stirred at room temperature to dissolve. To this, 0.467 g of a PGME dispersion of zirconia particles (PixClear manufactured by Pixelligent Technologies, average particle diameter 7 to 10 nm, zirconia concentration: 50% by mass) was added to prepare a charge-transporting varnish A.

[Comparative Example 1]
A mixture of 0.167 g of aniline derivative A and 0.333 g of aryl sulfonic acid ester C (D / H = 2.0 (molar ratio)), 4.75 g of triethylene glycol butyl methyl ether, 2.85 g of diisopropyl malonic acid and dimethyl phthalate. 1.9 g was added, and the mixture was stirred and dissolved at room temperature to prepare a charge-transporting varnish B.

[5] Production of thin film and evaluation of optical characteristics [Example 2]
The charge-transporting varnish A is applied to a quartz substrate using a spin coater, dried in the air at 120 ° C. for 1 minute, and then fired at 200 ° C. for 15 minutes to form a uniform thin film of 50 nm on the quartz substrate. did.

[Comparative Example 2]
A uniform thin film of 50 nm was formed on the quartz substrate by the same method as in Example 2 except that the charge transporting varnish B was used instead of the charge transporting varnish A.

Using the obtained quartz substrate with a film, the visible region average refractive index n and the visible region average extinction coefficient k were measured at a wavelength of 400 to 800 nm. The results are shown in Table 1.

As shown in Table 1, the thin film obtained from the charge-transporting varnish of the present invention showed a higher refractive index and a lower extinction coefficient than the thin film of the comparative example containing no particles.

[6] Fabrication of single-layer device and evaluation of characteristics [Example 3]
The charge-transporting varnish A is applied to an ITO substrate using a spin coater, dried in the air at 120 ° C. for 1 minute, and then fired at 200 ° C. for 15 minutes to form a uniform thin film of 50 nm on the ITO substrate. did. As the ITO substrate, a 25 mm × 25 mm × 0.7 t glass substrate having a patterned ITO film having a thickness of 50 nm formed on the surface was used, and the surface was subjected to an O ₂ plasma cleaning device (150 W, 30 seconds) before use. The above impurities were removed. Next, a single-layer device was produced by forming an aluminum film at 0.2 nm / sec at 80 nm on the ITO substrate on which the thin film was formed, using a vapor deposition apparatus (vacuum degree 1.0 × 10 ^-5 Pa). did.
In order to prevent deterioration of characteristics due to the influence of oxygen, water, etc. in the air, the elements were sealed with a sealing substrate and then their characteristics were evaluated. Sealing was performed by the following procedure. In a nitrogen atmosphere with an oxygen concentration of 2 ppm or less and a dew point of -76 ° C or less, the elements are placed between the sealing substrates, and the sealing substrates are bonded with an adhesive (Morresco Moisture Cut WB90US (P) manufactured by MORESCO Corporation). It was. At this time, a water trapping agent (HD-071010W-40 manufactured by Dynic Co., Ltd.) was housed in the sealing substrate together with the element. The bonded substrate was irradiated with UV light (wavelength: 365 nm, irradiation amount: 6,000 mJ / cm ² ) and then annealed at 80 ° C. for 1 hour to cure the adhesive.

The current density when the single-layer element obtained in Example 3 was driven at 5 V was measured. The results are shown in Table 3.

As shown in Table 2, it was found that the thin film prepared from the charge-transporting varnish of the present invention exhibited good charge-transporting property.

[7] Fabrication of a substrate with a charge-transporting thin film by coating with an inkjet [Example 4]
The charge-transporting varnish A is diluted with a solvent so that the solid content concentration is 2.3% by mass, and an inkjet device is placed in a rectangular opening (film forming region) on the partition substrate prepared in Production Example 2. Discharged using. When diluting the charge-transporting varnish, triethylene glycol butyl methyl ether, diisopropyl malonic acid and dimethyl phthalate were added so that the composition ratio of the mixed solvent in the varnish did not change. Immediately thereafter, the obtained coating film was dried under reduced pressure (vacuum degree) of 10 Pa or less at room temperature for 15 minutes, and then dried at 200 ° C. for 15 minutes at normal pressure to form a charge-transporting thin film in the partition wall. A substrate with a charge-transporting thin film was obtained. The charge-transporting thin film was discharged so that the film thickness near the center of the opening was 60 to 80 nm.

The shape of the surface of the charge-transporting thin film was measured with respect to the substrate with the charge-transporting thin film obtained in Example 4. The results are shown in FIG. In addition, the pile-up index was calculated for the prepared charge-transporting thin film. The pile-up index is (B) when the partition wall (bank) width is A (μm) and the film thickness range of + 10% from the film thickness of the charge-transporting thin film at the center of the partition wall (bank) is B (μm). It was calculated as / A) × 100 (%). The results are shown in Table 3. In Example 4, the pile-up index was calculated with the short side as the partition width.

As shown in FIGS. 1 and 3, for the substrate with the charge-transporting thin film produced by using the charge-transporting varnish of the present invention, the charge-transporting thin film shows good flatness and the pile-up index is 98. It showed a high value exceeding%.

Claims (11)

A charge-transporting varnish containing (A) zirconia particles surface-modified with a surface treatment agent, (B) a monodisperse charge-transporting organic compound, and (C) an organic solvent. The charge transporting varnish according to claim 1, wherein the zirconia particles surface-modified with the surface treatment agent have an average particle diameter of 2 to 100 nm. The charge-transporting varnish according to claim 1 or 2, wherein the charge-transporting organic compound contains at least one selected from an arylamine derivative, a thiophene derivative, and a pyrrole derivative. The charge-transporting varnish according to claim 3, wherein the charge-transporting organic compound contains an arylamine derivative. The charge-transporting varnish according to any one of claims 1 to 4, wherein the charge-transporting organic compound has a molecular weight of 200 to 9,000. The charge-transporting varnish according to any one of claims 1 to 5, wherein the charge-transporting organic compound is dissolved in the organic solvent. The charge transporting varnish according to any one of claims 1 to 6, further comprising (D) a dopant. The charge-transporting varnish according to claim 7, wherein the dopant (D) is an aryl sulfonic acid ester compound. A charge-transporting thin film obtained from the charge-transporting varnish according to any one of claims 1 to 8. The organic electroluminescence device including the charge transporting thin film according to claim 9. The organic electroluminescence device according to claim 10, wherein the charge transporting thin film is a hole injection layer or a hole transport layer.

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