Arylamine compound and use thereof
阅读说明：本技术 芳基胺化合物及其利用 (Arylamine compound and use thereof ) 是由 首藤圭介 远藤岁幸 于 2020-03-18 设计创作，主要内容包括：由下述式(1)表示的芳基胺化合物在有机溶剂中的溶解性良好,同时给予光学特性良好的薄膜,在将该薄膜应用于空穴注入层等的情况下能够实现具有良好的特性的有机EL元件。(式中,R～(1)各自独立地表示碳数6～20的芳基,R～(2)各自独立地表示氢原子、卤素原子、硝基、氰基、碳数1～20的烷基、碳数1～20的卤代烷基、碳数1～20的烷氧基、或者碳数6～20的芳基。)(An arylamine compound represented by the following formula (1) has good solubility in an organic solvent and gives a thin film having good optical characteristics, and when the thin film is applied to a hole injection layer or the like, an organic EL element having good characteristics can be realized. (in the formula, R 1 Each independently represents an aryl group having 6 to 20 carbon atoms, R 2 Each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. ))
1. An arylamine compound characterized by being represented by the following formula (1),
[ solution 1]
In the formula, R1Each independently represents an aryl group having 6 to 20 carbon atoms, R2Each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.
2. The arylamine compound according to claim 1, which is represented by the following formula (1-1):
[ solution 2]
In the formula, R1And R2The same meanings as described above are indicated.
3. The arylamine compound according to claim 2, which is represented by the following formula (1-1A) or (1-1B):
[ solution 3]
In the formula, R1And R2The same meanings as described above are indicated.
4. The arylamine compound according to any one of claims 1 to 3, wherein R is1Is phenyl, 1-naphthyl or 2-naphthyl.
5. The arylamine compound of claim 4 wherein R1All are phenyl groups.
6. The arylamine compound according to any one of claims 1 to 5, wherein R is2All are hydrogen atoms.
7. A charge-transporting varnish comprising the arylamine compound according to any one of claims 1 to 6 and an organic solvent.
8. The charge transport varnish of claim 7 comprising a dopant species.
9. The charge transport varnish of claim 8, wherein the dopant species is an aryl sulfonate compound.
10. A charge-transporting thin film produced using the charge-transporting varnish according to any one of claims 7 to 9.
11. An electronic component comprising the charge transporting thin film according to claim 10.
12. An organic electroluminescent element comprising the charge transporting thin film according to claim 10.
13. The organic electroluminescent element according to claim 12, wherein the charge-transporting thin film is a hole-injecting layer or a hole-transporting layer.
Technical Field
The present invention relates to arylamine compounds and use thereof.
Background
Organic electroluminescence (hereinafter, referred to as organic EL) devices are expected to be put to practical use in the fields of displays and lighting, and various developments have been made regarding materials and device structures for the purposes of low-voltage driving, high luminance, long life, and the like.
In the organic EL device, a plurality of functional thin films are used, and one of the hole injection layers is responsible for transferring charges between the anode and the hole transport layer or the light emitting layer, and plays an important role in realizing low-voltage driving and high luminance of the organic EL device.
The method of forming the hole injection layer is roughly classified into a dry method typified by a vapor deposition method and a wet method typified by a spin coating method. By comparing these methods, the wet method can efficiently produce a thin film having high flatness over a large area.
Therefore, at present, a hole injection layer that can be formed by a wet process is desired for increasing the area of an organic EL display.
In view of such circumstances, the present inventors have developed a charge transporting material that can be applied to various wet methods and that can provide a thin film that can realize excellent EL element characteristics when applied to a hole injection layer of an organic EL element, and a compound used for the charge transporting material and having good solubility in an organic solvent (see patent documents 1 to 3).
On the other hand, various studies have been made to improve the performance of organic EL devices, and for the purpose of improving light extraction efficiency, for example, studies have been made to adjust the refractive index of a functional film to be used. Specifically, it has been attempted to increase the efficiency of the element by using a hole injection layer and a hole transport layer having high or low refractive indices, taking into consideration the overall structure of the element and the refractive indices of other members adjacent to each other (see patent documents 4 and 5).
Therefore, the refractive index is an important factor in designing an organic EL element, and the refractive index is also considered as an important physical property value to be considered for a material for an organic EL element.
In addition, in recent years, it has been desired that charge-transporting thin films for organic EL devices have high transmittance and high transparency in the visible region, because of practical circumstances such as a decrease in color purity and color reproducibility of organic EL devices, for coloring of charge-transporting thin films used for organic EL devices (see patent document 6).
Therefore, in recent years when the organic EL display has been increased in area, development of the organic EL display using a wet process has been intensively carried out, and a material for a wet process which provides a charge-transporting thin film having good transparency has been demanded.
Documents of the prior art
Patent document
Patent document 1: international publication No. 2008/129947
Patent document 2: international publication No. 2015/050253
Patent document 3: international publication No. 2017/217457
Patent document 4: japanese Kokai publication No. 2007-536718
Patent document 5: japanese Kohyo publication 2017-501585
Patent document 6: international publication No. 2013/042623
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a thin film having good solubility in an organic solvent and good optical properties, and an arylamine compound which can realize an organic EL element having good properties when the thin film is applied to a hole injection layer or the like.
Means for solving the problems
The present inventors have made extensive studies to achieve the above object, and as a result, have found that: the present inventors have found that a predetermined arylamine compound having an arylcarbazole skeleton has good solubility in an organic solvent, and a varnish containing the compound gives a thin film having excellent optical characteristics, and that an organic EL element having excellent characteristics is obtained when the thin film is applied to a hole injection layer or the like, and have completed the present invention.
Namely, the present invention provides:
1. an arylamine compound characterized by being represented by the following formula (1),
[ solution 1]
(in the formula, R1Each independently represents an aryl group having 6 to 20 carbon atoms, R2Each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. )
2.1 an arylamine compound represented by the following formula (1-1),
[ solution 2]
(in the formula, R1And R2The same meanings as described above are indicated. )
3.2 an arylamine compound represented by the following formula (1-1A) or (1-1B),
[ solution 3]
(in the formula, R1And R2The same meanings as described above are indicated. )
4.1 to 3 of the arylamine compounds, wherein R is1Is phenyl, 1-naphthyl or 2-naphthyl,
an arylamine compound of 5.4 wherein R is1All of the phenyl groups are phenyl groups,
6.1 to 5, wherein R is an arylamine compound2All of which are hydrogen atoms,
7. a charge-transporting varnish comprising an arylamine compound of any one of 1 to 6 and an organic solvent,
8.7A charge-transporting varnish comprising a dopant species,
9.8 of the charge transporting varnish, wherein the dopant species is an aryl sulfonate compound,
10. a charge-transporting thin film produced using the charge-transporting varnish of any one of 7 to 9,
11. an electronic component comprising a charge transporting thin film of 10,
12. an organic electroluminescent element comprising a charge transporting thin film of 10,
the organic electroluminescent element according to 13.12, wherein the charge transporting thin film is a hole injecting layer or a hole transporting layer.
ADVANTAGEOUS EFFECTS OF INVENTION
The arylamine compound of the present invention has good solubility in an organic solvent, and a charge-transporting thin film having high transparency (low k (extinction coefficient)) and a high refractive index (high n) can be obtained by using a charge-transporting varnish containing the arylamine compound.
The charge-transporting thin film can be suitably used as a thin film for an electronic device such as an organic EL device, and particularly, by applying the charge-transporting thin film of the present invention to a hole injection layer or the like of an organic EL device, a device having good characteristics can be manufactured.
Detailed Description
The present invention is described in more detail below.
The arylamine compound according to the present invention is characterized by being represented by the following formula (1), and preferably represented by the formula (1-1).
[ solution 4]
[ solution 5]
In the formulae (1) and (1-1), R1Each independently represents an aryl group having 6 to 20 carbon atoms, R2Each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group having 1 to 20 carbon atomsA halogenated alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.
The alkyl group having 1 to 20 carbon atoms may be any of a straight-chain, branched-chain, and cyclic alkyl group, and examples thereof include a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group; and C3-20 cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, bicyclobutyl, bicyclopentyl, bicyclohexyl, bicycloheptyl, bicyclooctyl, bicyclononyl, and bicyclodecyl.
The alkoxy group having 1 to 20 carbon atoms, wherein the alkyl group may be a straight-chain, branched or cyclic alkyl group, and specific examples thereof include a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a n-pentoxy group, a n-hexoxy group, a n-octoxy group, a n-decoxy group, a 2-methylhexaxy group, a 2-ethylhexoxy group, a 2-n-propylhexoxy group, a 2-n-hexoxy group, a 2-ethyldecoxy group, a 3-ethylhexoxy group and the like.
Specific examples of the aryl group having 6 to 20 carbon atoms include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, and 9-phenanthryl.
The C1-20 haloalkyl group is a group obtained by substituting at least one hydrogen atom in the C1-20 alkyl group with a halogen atom, and as a specific example, examples thereof include fluoromethyl group, difluoromethyl group, trifluoromethyl group, bromodifluoromethyl group, 2-chloroethyl group, 2-bromoethyl group, 1, 1-difluoroethyl group, 2,2, 2-trifluoroethyl group, 1,1,2, 2-tetrafluoroethyl group, 2-chloro-1, 1, 2-trifluoroethyl group, pentafluoroethyl group, 3-bromopropyl group, 2,2,3, 3-tetrafluoropropyl group, 1,1,2, 3,3, 3-hexafluoropropyl group, 1,1, 1,3, 3, 3-hexafluoropropan-2-yl group, 3-bromo-2-methylpropyl group, 4-bromobutyl group, perfluoropentyl group, and 2- (perfluorohexyl) ethyl group.
In particular, if the solubility of the compound in organic solvents is taken into account, R1The aryl group has preferably 6 to 14 carbon atoms, more preferably phenyl, 1-naphthyl, and 2-naphthyl, even more preferably phenyl, 1-naphthyl, or 2-naphthyl, and even more preferably phenyl.
If the solubility of the compound in organic solvents is taken into account, R2Preferably hydrogen atom, alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, more preferably hydrogen atom, alkyl group having 1 to 10 carbon atoms, and further preferably all hydrogen atoms.
In the formula (1-1), the binding positions of 3 nitrogen atoms of the carbazole skeleton in the center and the carbazole ring of the arylcarbazole skeleton are not particularly limited, and they may be bound at the same position or at different positions, and preferably at the 3-position (meta-position) or the 4-position (para-position) with respect to the nitrogen atom of the arylcarbazole skeleton, as shown in the following formula (1-1A) or (1-1B), and more preferably at the 3-position.
[ solution 6]
(in the formula, R1And R2The same meanings as described above are indicated. )
Examples of the arylamine compound preferable in the present invention include compounds represented by the following formula (2) or (3), but are not limited thereto.
[ solution 7]
As shown in the following schemes, the arylamine compound represented by the formula (1) or (1-1) can be produced by reacting a diaminocarbazole compound [ Ia ] or [ Ib ] with a halogenated arylcarbazole compound [ II ] in the presence of a catalyst.
[ solution 8]
(wherein X represents a halogen atom or a pseudohalogen group, R1And R2The same meanings as described above are indicated. )
[ solution 9]
(in the formula, X, R1And R2The same meanings as described above are indicated. )
Examples of the halogen atom include the same halogen atoms as described above.
Examples of the pseudohalogen group include (fluoro) alkylsulfonyloxy groups such as methylsulfonyloxy, trifluoromethanesulfonyloxy and nonafluorobutanesulfonyloxy; and aromatic sulfonyloxy groups such as benzenesulfonyloxy and toluenesulfonyloxy.
The charging ratio of the diaminocarbazole compound [ Ia ] or [ Ib ] to the haloarylcarbazole compound [ II ] can be 5 equivalents or more, preferably about 5 to 5.5 equivalents, relative to the amount of the substance of all NH groups of the diaminocarbazole compound.
Examples of the catalyst used in the above reaction include copper catalysts such as copper chloride, copper bromide, and copper iodide; pd (PPh)3)4(tetrakis (triphenylphosphine) palladium), Pd (PPh)3)2Cl2(bis (triphenylphosphine) palladium dichloride), Pd (dba)2(bis (dibenzylideneacetone) palladium), Pd2(dba)3(tris (dibenzylideneacetone) dipalladium), Pd (P-t-Bu)3)2(bis (tris (t-butylphosphino)) palladium), Pd (OAc)2Palladium catalysts such as (palladium acetate) and the like. These catalysts may be used alone, or 2 or more of them may be used in combination. In addition, these catalysts may be used together with known appropriate ligands.
Examples of such ligands include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, and,Trimethylphosphine, triethylphosphine, tributylphosphine, tri-tert-butylphosphine, di-tert-butyl (4-dimethylaminophenyl) phosphine, 1, 2-bis (diphenylphosphino) ethane, 1, 3-bis (diphenylphosphino) propane, tertiary phosphines such as 1, 4-bis (diphenylphosphino) butane, 1 '-bis (diphenylphosphino) ferrocene, phosphite triesters such as trimethyl phosphite, triethyl phosphite, triphenyl phosphite, etc., commercially available from Aldrich, John Phos, CyjohnPhos, DavePhos, XPhos, SPhos, tBuXPhos, RuPhos, Me4 tBuhos, sSPhos, tBuMePhos, MePhos, tBu DavePhos, 2' -dicyclohexylphosphino-2, 4, 6-trimethoxybiphenyl, BrettPhos, BretPhos, BrutBuphos, Adethis3And (OMe) tBuXPhos, (2-biphenyl) di-1-adamantylphosphine, RockPhos, CPhos, and the like.
The amount of the catalyst to be used may be about 0.01 to 0.5mol, preferably about 0.05 to 0.2mol, based on 1mol of the haloarylcarbazole compound [ II ].
When the ligand is used, the amount of the ligand used can be 0.1 to 5 equivalents, preferably 1 to 2 equivalents, based on the metal complex used.
In addition, a base may be used in the above reaction. Examples of the base include simple alkali metals such as lithium, sodium, potassium, lithium hydride, sodium hydride, lithium hydroxide, potassium hydroxide, t-butoxylithium, t-butoxysodium, t-butoxypotassium, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, and potassium hydrogencarbonate, alkali metals such as alkali hydrides, alkali metals hydroxides, alkali metal alkoxides, alkali metals carbonates, and alkali metals hydrogencarbonate; alkali earth carbonate metals such as calcium carbonate; organolithium such as n-butyllithium, sec-butyllithium, tert-butyllithium, Lithium Diisopropylamide (LDA), lithium 2,2, 6, 6-tetramethylpiperidine (LiTMP), Lithium Hexamethyldisilazane (LHMDS); amines such as triethylamine, diisopropylethylamine, tetramethylethylenediamine, triethylenediamine, and pyridine.
When a base is used, the amount of the base used can be 0.1 to 5 equivalents, preferably 1 to 2 equivalents, based on the amount of the haloarylcarbazole compound [ II ] used.
In the case where all of the raw material compounds are solid or from the viewpoint of efficiently obtaining the target arylamine compound, the above-mentioned respective reactions are carried out in a solvent. When a solvent is used, the kind thereof is not particularly limited as long as it does not adversely affect the reaction. Specific examples thereof include aliphatic hydrocarbons (e.g., pentane, N-hexane, N-octane, N-decane, decalin), halogenated aliphatic hydrocarbons (e.g., chloroform, dichloromethane, dichloroethane, and carbon tetrachloride), aromatic hydrocarbons (e.g., benzene, nitrobenzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene), halogenated aromatic hydrocarbons (e.g., chlorobenzene, bromobenzene, o-dichlorobenzene, m-dichlorobenzene, and p-dichlorobenzene), ethers (e.g., diethyl ether, diisopropyl ether, tert-butyl methyl ether, tetrahydrofuran, dioxane, 1, 2-dimethoxyethane, 1, 2-diethoxyethane), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, di-N-butyl ketone, and cyclohexanone), amides (e.g., N-dimethylformamide and N, N-dimethylacetamide), lactams, and lactones (e.g., N-methylpyrrolidone), γ -butyrolactone, etc.), ureas (N, N-dimethylimidazolidinone, tetramethylurea, etc.), sulfoxides (dimethyl sulfoxide, sulfolane, etc.), nitriles (acetonitrile, propionitrile, butyronitrile, etc.), etc., and these solvents may be used alone or in combination of 2 or more.
The reaction temperature may be suitably set in a range from the melting point to the boiling point of the solvent used, and is preferably about 0 to 200 ℃ and more preferably 20 to 150 ℃.
After the reaction is completed, the target arylamine compound can be obtained by performing post-treatment according to a conventional method.
The arylamine compound of the present invention can be preferably used as a charge transporting substance. In this case, the aromatic amine compound of the present invention can be used as a charge-transporting varnish containing an organic solvent, and the charge-transporting varnish may contain a dopant substance for the purpose of, for example, improving the charge-transporting ability of the resulting thin film depending on the application. The arylamine compound of the present invention can be used in combination with other conventionally known charge-transporting substances such as aniline derivatives and thiophene derivatives, and the arylamine compound of the present invention is preferably used alone as the charge-transporting substance.
In the present invention, the term "charge transporting property" is synonymous with conductivity. The charge-transporting varnish may have a charge-transporting property by itself, or a solid film obtained therefrom may have a charge-transporting property.
The dopant substance is not particularly limited as long as it is dissolved in at least 1 kind of solvent used in the varnish, and both an inorganic dopant substance and an organic dopant substance can be used.
The dopant substance may be used alone in 1 kind or in combination of 2 or more kinds.
Further, the dopant substance may be a substance in which, for example, a part of the molecule is desorbed by an external stimulus such as heating at the time of firing during the process of obtaining a charge-transporting thin film as a solid film from a varnish, and the function as the dopant substance is first developed or improved, and may be, for example, an arylsulfonate compound protected with a group from which a sulfonic acid group is easily desorbed.
In particular, in the present invention, as the inorganic dopant substance, heteropoly acid is preferable.
The heteropoly acid is a polyacid having a structure in which a hetero atom is located at the center of a molecule, typically represented by a chemical structure of Keggin type represented by formula (H1) or Dawson type represented by formula (H2), and which is obtained by condensing an isopoly acid, which is an oxyacid such as vanadium (V), molybdenum (Mo), tungsten (W), or the like, with an oxyacid of a different element. Examples of the oxo acid of such a different element include oxo acids of silicon (Si), phosphorus (P), and arsenic (As).
[ solution 10]
Specific examples of the heteropoly-acid include phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid, silicotungstic acid, phosphotungstomolybdic acid, and the like, and these heteropoly-acids may be used alone or in combination of 2 or more kinds. These heteropoly acids are commercially available, and can be synthesized by a known method.
In particular, in the case of using 1 kind of heteropoly acid, the 1 kind of heteropoly acid is preferably phosphotungstic acid or phosphomolybdic acid, and most preferably phosphotungstic acid. In addition, in the case of using 2 or more kinds of heteropolyacids, 1 of the 2 or more kinds of heteropolyacids is preferably phosphotungstic acid or phosphomolybdic acid, and more preferably phosphotungstic acid.
In quantitative analysis such as elemental analysis, the heteropoly-acid can be used in the present invention even if the number of elements is large or small relative to the structure represented by the general formula, as long as it is a product obtained as a commercially available product or a product appropriately synthesized by a known synthesis method.
That is, for example, in general, phosphotungstic acid has the formula H3(PW12O40)·nH2O represents, phosphomolybdic acid has the chemical formula H3(PMo12O40)·nH2In the quantitative analysis, the O-based compound can be used in the present invention even if the number of P (phosphorus), O (oxygen), W (tungsten), or Mo (molybdenum) in the formula is large or small, as long as it is a product obtained as a commercially available product or a product appropriately synthesized by a known synthesis method. In this case, the mass of the heteropoly-acid specified in the present invention is not the mass of pure phosphotungstic acid (phosphotungstic acid content) in a synthetic product or a commercially available product, but means the total mass in a state where water of hydration, other impurities and the like are contained in a form obtainable as a commercially available product or in a form separable by a known synthesis method.
The amount of the heteropoly acid used can be about 0.001 to 50.0, preferably about 0.01 to 20.0, and more preferably about 0.1 to 10.0, in terms of mass ratio, relative to the charge transporting substance 1.
On the other hand, as the organic dopant substance, in particular, tetracyanoquinodimethane derivatives and benzoquinone derivatives can be used.
Specific examples of the tetracyanoquinodimethane derivative include 7,7,8, 8-Tetracyanoquinodimethane (TCNQ) and halogenated tetracyanoquinodimethane represented by the formula (H3).
Specific examples of the benzoquinone derivative include tetrafluoro-1, 4-benzoquinone (F4BQ), tetrachloro-1, 4-benzoquinone (tetrachloro-p-benzoquinone), tetrabromo-1, 4-benzoquinone, and 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ).
[ solution 11]
In the formula, R500～R503Each independently represents a hydrogen atom or a halogen atom, at least 1 being a halogen atom, preferably at least 2 being a halogen atom, more preferably at least 3 being a halogen atom, most preferably all being a halogen atom.
Examples of the halogen atom include the same halogen atoms as described above, preferably a fluorine atom or a chlorine atom, and more preferably a fluorine atom.
Specific examples of such a halogenated tetracyanoquinodimethane include 2-fluoro-7, 7,8, 8-tetracyanoquinodimethane, 2-chloro-7, 7,8, 8-tetracyanoquinodimethane, 2, 5-difluoro-7, 7,8, 8-tetracyanoquinodimethane, 2, 5-dichloro-7, 7,8, 8-tetracyanoquinodimethane, 2,3,5, 6-tetrachloro-7, 7,8, 8-tetracyanoquinodimethane, 2,3,5, 6-tetrafluoro-7, 7,8, 8-tetracyanoquinodimethane (F4TCNQ), and the like.
The amount of the tetracyanoquinodimethane derivative and the benzoquinone derivative to be used is preferably 0.0001 to 100 equivalents, more preferably 0.01 to 50 equivalents, and still more preferably 1 to 20 equivalents, based on the charge transporting substance.
As the organic dopant substance, an electrically neutral onium borate containing an anion having a valence of 1 or 2 represented by the following formula (a1) and counter cations represented by the formulae (c1) to (c5) can be used.
[ solution 12]
(wherein Ar independently represents an aryl group having 6 to 20 carbon atoms which may have a substituent or a heteroaryl group having 2 to 20 carbon atoms which may have a substituent, L represents an alkylene group having 1 to 20 carbon atoms, -NH-Oxygen atom, sulfur atom or-CN+-。)
[ solution 13]
In the formula (a1), the alkylene group having 1 to 20 carbon atoms may be any of a linear, branched, or cyclic alkylene group, and specific examples thereof include methylene, methylmethylene, dimethylmethylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and hexamethylene. Examples of the aryl group and the heteroaryl group include the same ones as described above.
Preferred examples of the anion of the formula (a1) include anions represented by the formula (a2), but are not limited thereto.
[ solution 14]
The amount of the onium borate to be used can be about 0.1 to 10 in terms of the ratio of the amount of the substance (molar ratio) to the charge transporting substance.
The onium borate can be synthesized by a known method described in, for example, Japanese patent application laid-open No. 2005-314682.
Further, as the organic dopant substance, an arylsulfonic acid compound or an arylsulfonate compound can also be preferably used.
Specific examples of the arylsulfonic acid compound include benzenesulfonic acid, toluenesulfonic acid, p-styrenesulfonic acid, 2-naphthalenesulfonic acid, 4-hydroxybenzenesulfonic acid, 5-sulfosalicylic acid, p-dodecylbenzenesulfonic acid, dihexylbenzenesulfonic acid, 2, 5-dihexylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, 6, 7-dibutyl-2-naphthalenesulfonic acid, dodecylnaphthalenesulfonic acid, 3-dodecyl-2-naphthalenesulfonic acid, hexylnaphthalenesulfonic acid, 4-hexyl-1-naphthalenesulfonic acid, octylnaphthalenesulfonic acid, 2-octyl-1-naphthalenesulfonic acid, hexylnaphthalenesulfonic acid, 7-hexyl-1-naphthalenesulfonic acid, 6-hexyl-2-naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, 2, 7-dinonyl-4-naphthalenesulfonic acid, p-styrenesulfonic acid, 2-naphthalenesulfonic acid, 5-butylnaphthalenesulfonic acid, 4-hydroxybenzenesulfonic acid, 5-sulfobenzoic acid, 5-dimethylnaphthalenesulfonic acid, and dimethylnaphthalenesulfonic acid, Dinonylnaphthalenedisulfonic acid, 2, 7-dinonyl-4, 5-naphthalenedisulfonic acid, a1, 4-benzodioxan disulfonic acid compound described in International publication No. 2005/000832, an arylsulfonic acid compound described in International publication No. 2006/025342, an arylsulfonic acid compound described in International publication No. 2009/096352, and the like.
Examples of preferred arylsulfonic acid compounds include arylsulfonic acid compounds represented by the formula (H4) or (H5).
[ solution 15]
A1Represents O or S, preferably O.
A2Represents a naphthalene ring or an anthracene ring, preferably a naphthalene ring.
A3Represents a 2-4 valent perfluorobiphenyl group, p represents A1And A3The number of binding(s) is an integer satisfying 2. ltoreq. p.ltoreq.4, preferably A3Is perfluorobiphenylene, preferably perfluorobiphenyl-4, 4' -diyl, and p is 2.
q represents the same as A2The number of the sulfonic acid groups bonded is an integer satisfying 1. ltoreq. q.ltoreq.4, and 2 is most preferable.
A4～A8Each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, or a haloalkenyl group having 2 to 20 carbon atoms, A4～A8At least 3 of which are halogen atoms.
Examples of the haloalkyl group having 1 to 20 carbon atoms include a trifluoromethyl group, a2, 2, 2-trifluoroethyl group, a1, 1,2,2, 2-pentafluoroethyl group, a 3,3, 3-trifluoropropyl group, a2, 2,3,3, 3-pentafluoropropyl group, a1, 1,2,2,3,3, 3-heptafluoropropyl group, a 4,4, 4-trifluorobutyl group, a 3,3,4,4, 4-pentafluorobutyl group, a2, 2,3,3,4, 4-heptafluorobutyl group, a1, 1,2,2,3,3,4,4, 4-nonafluorobutyl group and the like.
Examples of the haloalkenyl group having 2 to 20 carbon atoms include a perfluorovinyl group, a perfluoropropenyl group (allyl group), a perfluorobutenyl group, and the like.
Examples of the halogen atom and the alkyl group having 1 to 20 carbon atoms include the same ones as described above, and the halogen atom is preferably a fluorine atom.
Of these, A is preferred4～A8Is a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, or a haloalkenyl group having 2 to 10 carbon atoms, and A4～A8At least 3 of which are fluorine atoms, more preferably hydrogen atoms, fluorine atoms, cyano groups, alkyl groups having 1 to 5 carbon atoms, fluoroalkyl groups having 1 to 5 carbon atoms, or fluoroalkenyl groups having 2 to 5 carbon atoms, and A4～A8At least 3 of them are fluorine atoms, more preferably hydrogen atoms, fluorine atoms, cyano groups, perfluoroalkyl groups having 1 to 5 carbon atoms, or perfluoroalkenyl groups having 1 to 5 carbon atoms, and A4、A5And A8Is a fluorine atom.
The perfluoroalkyl group is a group in which all hydrogen atoms of the alkyl group have been substituted with fluorine atoms, and the perfluoroalkenyl group is a group in which all hydrogen atoms of the alkenyl group have been substituted with fluorine atoms.
r represents the number of sulfonic acid groups bonded to the naphthalene ring, and is an integer satisfying 1. ltoreq. r.ltoreq.4, preferably 2 to 4, and most preferably 2.
The molecular weight of the arylsulfonic acid compound used as a dopant substance is not particularly limited, but is preferably 2000 or less, more preferably 1500 or less, in consideration of solubility in an organic solvent when used together with the arylamine compound of the present invention.
Specific examples of preferred arylsulfonic acid compounds are listed below, but the aryl sulfonic acid compounds are not limited thereto.
[ solution 16]
The amount of the arylsulfonic acid compound used is preferably about 0.01 to 20.0, and more preferably about 0.4 to 5.0 in terms of the ratio of the amount of the substance (mole) to the charge transporting substance 1.
The arylsulfonic acid compound can be synthesized by a commercially available method or by a known method described in international publication No. 2006/025342, international publication No. 2009/096352, and the like.
On the other hand, examples of the arylsulfonate compound include an arylsulfonate compound disclosed in international publication No. 2017/217455, an arylsulfonate compound disclosed in international publication No. 2017/217457, and an arylsulfonate compound described in japanese patent application No. 2017-243631, and specifically, compounds represented by any one of the following formulae (H6) to (H8) are preferable.
[ solution 17]
(wherein m is an integer satisfying 1. ltoreq. m.ltoreq.4, preferably 2. n is an integer satisfying 1. ltoreq. n.ltoreq.4, preferably 2.)
In the formula (H6), A11Is a m-valent group derived from perfluorobiphenyl.
A12is-O-or-S-, preferably-O-.
A13Is a (n +1) -valent group derived from naphthalene or anthracene, preferably a group derived from naphthalene.
Rs1～Rs4Each independently represents a hydrogen atom or a straight or branched alkyl group having 1 to 6 carbon atoms, Rs5Is a 1-valent hydrocarbon group having 2 to 20 carbon atoms which may be substituted.
Specific examples of the linear or branched alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl and the like, and an alkyl group having 1 to 3 carbon atoms is preferable.
The 1-valent hydrocarbon group having 2 to 20 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include alkyl groups such as ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group; aryl groups such as phenyl, naphthyl and phenanthryl.
In particular, in Rs1～Rs4Among them, R is preferreds1Or Rs3Is a straight-chain alkyl group having 1 to 3 carbon atoms, the remainder being hydrogen atoms, or Rs1Is a C1-3 linear alkyl group, Rs2～Rs4Is a hydrogen atom. In this case, the straight-chain alkyl group having 1 to 3 carbon atoms is preferably a methyl group.
In addition, as Rs5Preferably, the alkyl group or phenyl group has 2 to 4 carbon atoms.
In the formula (H7), A14Is a substituted, m-valent hydrocarbon group having 6 to 20 carbon atoms and containing 1 or more aromatic rings, wherein the hydrocarbon group is obtained by removing m hydrogen atoms from a hydrocarbon compound having 6 to 20 carbon atoms and containing 1 or more aromatic rings.
Examples of such hydrocarbon compounds include benzene, toluene, xylene, ethylbenzene, biphenyl, naphthalene, anthracene, phenanthrene, and the like.
Further, the above-mentioned hydrocarbon group may have a part or all of its hydrogen atoms substituted with a substituent, and examples of such a substituent include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a nitro group, a cyano group, a hydroxyl group, an amino group, a silanol group, a thiol group, a carboxyl group, a sulfonate ester, a phosphoric acid, a phosphate ester, an ester, a thioester, an amide, an organoxy group, an organoamino group, an organosilyl group, an organosulfuryl group, an acyl group, a sulfo group, a 1-valent hydrocarbon group, and the like.
Among these, as A14Groups derived from benzene, biphenyl, etc. are preferred.
In addition, A15is-O-or-S-, preferably-O-.
A16The aromatic hydrocarbon compound is an (n +1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein the aromatic hydrocarbon group is obtained by removing (n +1) hydrogen atoms from an 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.
Wherein, as A16Preferably a naphthalene or anthracene derived group, more preferably a naphthalene derived group.
Rs6And Rs7Each independentlyIs a hydrogen atom or a straight or branched aliphatic hydrocarbon group having a valence of 1, Rs8Is a straight chain or branched chain 1-valent aliphatic hydrocarbon group. However, Rs6、Rs7And Rs8The total number of carbon atoms of (2) is 6 or more. To Rs6、Rs7And Rs8The upper limit of the total number of carbon atoms of (3) is not particularly limited, but is preferably 20 or less, and more preferably 10 or less.
Specific examples of the linear or branched 1-valent aliphatic hydrocarbon group include alkyl groups having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-hexyl group, a n-octyl group, a 2-ethylhexyl group, and a decyl group; and alkenyl groups having 2 to 20 carbon atoms such as vinyl, 1-propenyl, 2-propenyl, isopropenyl, 1-methyl-2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, hexenyl, and the like.
In these, Rs6Preferably a hydrogen atom, Rs7And Rs8Each independently preferably an alkyl group having 1 to 6 carbon atoms.
In the formula (H8), Rs9～Rs13Each independently represents a hydrogen atom, a nitro group, a cyano group, a halogen atom, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, or a haloalkenyl 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, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl and n-decyl groups.
The haloalkyl 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 hydrogen atoms of the alkyl group having 1 to 10 carbon atoms are substituted with a halogen atom, and specific examples thereof include a trifluoromethyl group, a2, 2, 2-trifluoroethyl group, a1, 1,2, 2-pentafluoroethyl group, a 3,3, 3-trifluoropropyl group, a2, 2,3,3, 3-pentafluoropropyl group, a1, 1,2,2,3,3, 3-heptafluoropropyl group, a 4,4, 4-trifluorobutyl group, a 3,3,4,4, 4-pentafluorobutyl group, a2, 2,3,3,4, 4-heptafluorobutyl group, a1, 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 hydrogen atoms of an alkenyl group having 2 to 10 carbon atoms are substituted with halogen atoms, and specific examples thereof include perfluorovinyl group, perfluoro-1-propenyl group, perfluoro-2-propenyl group, perfluoro-1-butenyl group, perfluoro-2-butenyl group, perfluoro-3-butenyl group, and the like.
Among these, as Rs9The compound is preferably a nitro group, a cyano group, a haloalkyl group having 1 to 10 carbon atoms, or a haloalkenyl group having 2 to 10 carbon atoms, more preferably a nitro group, a cyano group, a haloalkyl group having 1 to 4 carbon atoms, or a haloalkenyl group having 2 to 4 carbon atoms, and still more preferably a nitro group, a cyano group, a trifluoromethyl group, or a perfluoropropenyl group.
As Rs10～Rs13Preferably a halogen atom, more preferably a fluorine atom.
A17is-O-, -S-or-NH-, preferably-O-.
A18The aromatic hydrocarbon compound is an (n +1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein the aromatic hydrocarbon group is obtained by removing (n +1) hydrogen atoms from an 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.
Among these, as A18Preferably a naphthalene or anthracene derived group, more preferably a naphthalene derived group.
Rs14～Rs17Each independently represents a hydrogen atom or a straight or branched aliphatic hydrocarbon group having 1 to 20 carbon atoms and a valence of 1.
Specific examples of the 1-valent aliphatic hydrocarbon group include alkyl groups having 1 to 20 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, and the like; an alkenyl group having 2 to 20 carbon atoms such as a vinyl group, a 1-propenyl group, a 2-propenyl group, an isopropenyl group, a 1-methyl-2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, and a hexenyl group, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 8 carbon atoms.
Rs18Is a straight-chain OR branched-chain 1-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms, OR ORs19。Rs19Is a 1-valent hydrocarbon group having 2 to 20 carbon atoms which may be substituted.
As Rs18Examples of the linear or branched 1-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms include the same groups as described above.
At Rs18In the case of a 1-valent aliphatic hydrocarbon group, Rs18The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and still more preferably 1 to 8 carbon atoms.
As Rs19Examples of the 1-valent hydrocarbon group having 2 to 20 carbon atoms include aryl groups such as phenyl, naphthyl and phenanthryl groups, in addition to the groups other than methyl in the 1-valent aliphatic hydrocarbon group.
In these, Rs19Preferably a C2-4 linear alkyl group or a phenyl group.
Further, examples of the substituent that the 1-valent hydrocarbon group may have include a fluorine atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group and the like.
Specific examples of preferred arylsulfonate compounds include, but are not limited to, the following.
[ solution 18]
The amount of the arylsulfonate compound used is preferably about 0.01 to 20, and more preferably about 0.05 to 10 in terms of the ratio of the amount of the substance (mole) to the charge transporting substance 1.
In the present invention, if it is considered that a charge transporting thin film having excellent transparency and a high refractive index is to be produced, it is preferable to use an arylsulfonic acid compound or an arylsulfonic acid ester compound as a dopant substance, and if it is considered that a thin film having a lower solubility in a solvent and a lower extinction coefficient is to be obtained, it is more preferable to use an arylsulfonic acid ester compound.
Further, when the obtained thin film is used as a hole injection layer of an organic EL device, the charge-transporting varnish may contain an organic silane compound for the purpose of improving the injection property into the hole transport layer, the life characteristics of the device, and the like. The content thereof is usually about 1 to 30% by mass relative to the total mass of the charge transporting substance and the dopant substance.
As the organic solvent used in the preparation of the charge-transporting varnish of the present invention, a highly polar solvent capable of dissolving the arylamine compound of the present invention can be used. The arylamine compound of the present invention is soluble in a solvent regardless of the polarity of the solvent. If necessary, a low-polarity solvent can be used because it is more suitable for the process than a high-polarity solvent. In the present invention, the low-polarity solvent is defined as a solvent having a relative dielectric constant of less than 7 at a frequency of 100kHz, and the high-polarity solvent is defined as a solvent having a relative dielectric constant of 7 or more at a frequency of 100 kHz.
Examples of the low-polarity solvent include
Chlorine-based solvents such as chloroform and chlorobenzene;
aromatic hydrocarbon solvents such as toluene, xylene, tetrahydronaphthalene, cyclohexylbenzene, and decylbenzene;
aliphatic alcohol solvents such as 1-octanol, 1-nonanol, and 1-decanol;
ether solvents such as tetrahydrofuran, dioxane, anisole, 4-methoxytoluene, 3-phenoxytoluene, dibenzyl ether, diethylene glycol dimethyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, and triethylene glycol butyl methyl ether;
ester solvents such as methyl benzoate, ethyl benzoate, butyl benzoate, isoamyl benzoate, di (2-ethylhexyl) phthalate, dibutyl maleate, dibutyl oxalate, hexyl acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate.
Examples of the highly polar solvent include
Amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-dimethylisobutylamide, N-methylpyrrolidone, and 1, 3-dimethyl-2-imidazolidinone;
ketone solvents such as methyl ethyl ketone, isophorone, and cyclohexanone;
cyano solvents such as acetonitrile and 3-methoxypropionitrile;
polyhydric alcohol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1, 3-butanediol, and 2, 3-butanediol;
1-membered alcohol solvents other than aliphatic alcohols, such as diethylene glycol monomethyl ether, diethylene glycol monophenyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, benzyl alcohol, 2-phenoxyethanol, 2-benzyloxyethanol, 3-phenoxybenzyl alcohol, and tetrahydrofurfuryl alcohol;
sulfoxide solvents such as dimethyl sulfoxide, and the like.
The viscosity of the charge-transporting varnish is determined appropriately depending on the solid content concentration such as the thickness of the film to be produced, and is usually 1 to 50 mPas at 25 ℃. In the present invention, the solid component means a component other than the solvent contained in the charge-transporting varnish.
The solid content concentration of the charge-transporting varnish is appropriately set in consideration of viscosity, surface tension, etc. of the varnish, the thickness of the film to be produced, etc., and is usually about 0.1 to 10.0 mass%, and if the coatability of the varnish is improved, it is preferably about 0.5 to 5.0 mass%, and more preferably about 1.0 to 3.0 mass%.
The method for producing the charge-transporting varnish is not particularly limited, and examples thereof include a method in which a solid component such as a charge-transporting substance containing the arylamine compound of the present invention is dissolved in a highly polar solvent, and a low-polar solvent is added thereto; and a method of mixing a high-polarity solvent and a low-polarity solvent to dissolve the charge transporting substance therein.
In particular, in the production of the charge-transporting varnish, it is preferable to dissolve the charge-transporting substance, the dopant substance, and the like in the organic solvent and then perform filtration using a submicron filter or the like, from the viewpoint of obtaining a thin film having higher flatness with good reproducibility.
The charge-transporting varnish described above can be used to easily produce a charge-transporting thin film, and therefore can be suitably used for producing electronic devices, particularly organic EL devices.
In this case, the charge-transporting thin film can be formed by applying the above-mentioned charge-transporting varnish on a substrate and firing the applied varnish.
The method of applying the varnish is not particularly limited, and examples thereof include a dipping method, a spin coating method, a transfer printing method, a roll coating method, a brush coating method, an ink jet method, a spray coating method, and a slit coating method.
Further, the firing atmosphere of the charge-transporting varnish after coating is not particularly limited, and a thin film having a uniform film formation surface and a high charge-transporting property can be obtained not only in an atmospheric atmosphere but also in an inert gas such as nitrogen or in a vacuum.
The firing temperature is appropriately set in the range of about 100 to 260 ℃ in consideration of the application of the obtained film, the degree of charge transport property imparted to the obtained film, the kind of solvent, the boiling point, and the like, and for example, when the obtained film is used as a hole injection layer of an organic EL element, about 140 to 250 ℃ is preferable, and about 145 to 240 ℃ is more preferable, and when the arylamine compound represented by the above formula (1) is used as a charge transport material, a film having good charge transport property can be obtained even when fired at a low temperature of 200 ℃ or less.
In addition, in order to develop a more uniform film-forming property and to allow the reaction to proceed on the substrate, the heating may be performed by giving a temperature change of 2 stages or more, and for example, by using an appropriate device such as a hot plate or an oven.
The film thickness of the charge transporting thin film is not particularly limited, and is preferably 5 to 300nm when the charge transporting thin film is used as a functional layer provided between an anode and a light-emitting layer, such as a hole injection layer, a hole transport layer, or a hole injection transport layer of an organic EL device. As a method of changing the film thickness, there are methods of changing the concentration of solid components in the varnish, changing the amount of solution on the substrate at the time of coating, and the like.
The charge transporting thin film of the present invention described above generally exhibits a refractive index (n) of 1.50 or more and an extinction coefficient (k) of 0.10 or less, as represented by an average value in a wavelength region of 400 to 800nm, and in one embodiment exhibits a refractive index (n) of 1.60 or more, in another embodiment exhibits a refractive index (n) of 1.70 or more, in one embodiment exhibits an extinction coefficient (k) of 0.07 or less, and in another embodiment exhibits an extinction coefficient (k) of 0.02 or less.
When the charge-transporting thin film is applied to an organic EL element, the charge-transporting thin film may be provided between a pair of electrodes constituting the organic EL element.
Representative configurations of the organic EL element include the following (a) to (f), but are not limited thereto. In the following configuration, an electron blocking layer or the like may be provided between the light-emitting layer and the anode, and a hole (hole) blocking layer or the like may be provided between the light-emitting layer and the cathode, as necessary. The hole injection layer, the hole transport layer, or the hole injection transport layer may have a function as an electron blocking layer or the like, and the electron injection layer, the electron transport layer, or the electron injection transport layer may have a function as a hole (hole) blocking layer or the like. Further, an arbitrary functional layer may be provided between the layers as necessary.
(a) Anode/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/luminescent layer/electron transport layer/electron injection layer/cathode
(d) Anode/hole injection transport layer/light emitting layer/electron injection transport layer/cathode
(e) Anode/hole injection layer/hole transport layer/light emitting layer/cathode
(f) Anode/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 have a function of transporting holes from the anode to the light-emitting layer, and are "hole injection transport layer" when only 1 layer of a hole-transporting material is provided between the light-emitting layer and the anode, and are "hole injection layer" when 2 or more layers of a hole-transporting material are provided between the light-emitting layer and the anode, the layer close to the anode is the "hole injection layer", and the other layers are the "hole transport layers". In particular, a thin film excellent in hole accepting property from the anode and hole injecting property into the hole transporting (light emitting) layer is used as the hole injecting (transporting) layer.
The "electron injection layer", "electron transport layer" and "electron injection 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, and are the "electron injection transport layer" when only 1 layer of an electron-transporting material is provided between the light-emitting layer and the cathode, and are the "electron injection layer" when 2 or more layers of an electron-transporting material are provided between the light-emitting layer and the cathode, the layer close to the cathode is the "electron injection layer", and the other layers are the "electron transport layers".
The "light-emitting layer" is an organic layer having a light-emitting function, and in the case of using a dopant system, includes a host material and a dopant material. In this case, the host material mainly has a function of promoting recombination of electrons and holes and confining excitons in the light-emitting layer, and the dopant material has a function of efficiently emitting excitons obtained by the recombination. In the case of a phosphorescent element, the host material mainly has a function of confining excitons generated from the dopant within the light emitting layer.
The charge-transporting thin film of the present invention is useful as a functional layer provided between an anode and a light-emitting layer in an organic EL device, preferably as a hole injection layer, a hole transport layer, or a hole injection transport layer, more preferably as a hole injection layer or a hole transport layer, and still more preferably as a hole injection layer.
The materials and the methods for producing an EL element using the charge-transporting varnish of the present invention include, but are not limited to, the following materials and methods.
An example of a method for producing an OLED element having a hole injection layer formed of a thin film obtained from the charge-transporting varnish of the present invention is as follows. Furthermore, it is preferable that the electrode is previously cleaned with alcohol, pure water, or the like within a range that does not adversely affect the electrode; surface treatment such as UV ozone treatment, oxygen-plasma treatment, or the like is employed.
The hole injection layer composed of the charge transport thin film of the present invention is formed on the anode substrate by the above method. The organic electroluminescent material is introduced into a vacuum evaporation device, and a hole transport layer, a luminescent layer, an electron transport layer/hole barrier layer and cathode metal are evaporated in sequence. Alternatively, in this method, instead of forming the hole transport layer and the light-emitting layer by vapor deposition, 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, and these layers are formed by a wet method. Further, an electron blocking layer may be provided between the light-emitting layer and the hole transporting layer as necessary.
Examples of the anode material include a transparent electrode typified by Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO), a metal anode typified by aluminum, an alloy thereof, and the like, and a flattened anode material is preferable. Polythiophene derivatives and polyaniline derivatives having high charge transport properties can also be used.
Examples of the other metal constituting the metal anode include gold, silver, copper, indium, and alloys thereof, but are not limited thereto.
Examples of the material for forming the hole transport layer include triarylamines such as (triphenylamine) dimer derivatives, [ (triphenylamine) dimer ] spiro dimer, N '-bis (naphthalene-1-yl) -N, N' -bis (phenyl) -benzidine (. alpha. -NPD), 4 '-tris [ 3-methylphenyl (phenyl) amino ] triphenylamine (m-MTDATA), and 4, 4' -tris [ 1-naphthyl (phenyl) amino ] triphenylamine (1-TNATA), and 5, 5 '-bis- {4- [ bis (4-methylphenyl) amino ] phenyl } -2, 2': and oligophenes such as 5 ', 2' -terthiophene (BMA-3T).
Examples of the material for forming the light-emitting layer include low-molecular-weight light-emitting materials such as metal complexes of 8-hydroxyquinoline and the like, metal complexes of 10-hydroxybenzo [ h ] quinoline, bisstyrylbenzene derivatives, bisstyrylarylene derivatives, metal complexes of (2-hydroxyphenyl) benzothiazole, silole derivatives and the like; and a system in which a light-emitting material and an electron-transporting material are mixed in a polymer compound such as poly (p-phenylene vinylene), poly [ 2-methoxy-5- (2-ethylhexyloxy) -1, 4-phenylene vinylene ], poly (3-alkylthiophene) or polyvinylcarbazole, but the present invention is not limited thereto.
In addition, when the light-emitting layer is formed by vapor deposition, the light-emitting layer may be co-deposited with a light-emitting dopant, and examples of the light-emitting dopant include tris (2-phenylpyridine) iridium (III) (ir (ppy)3) And the like, tetracene derivatives such as rubrene, quinacridone derivatives, fused polycyclic aromatic rings such as perylene, and the like, but are not limited thereto.
Examples of the material for forming the electron transport layer/hole blocking layer include, but are not limited to, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, phenylquinoxaline derivatives, benzimidazole derivatives, and pyrimidine derivatives.
As a material for forming the electron injection layer, lithium oxide (Li) can be mentioned2O), magnesium oxide (MgO), aluminum oxide (Al)2O3) And the like, lithium fluoride (LiF), and sodium fluoride (NaF), but are not limited thereto.
Examples of the cathode material include, but are not limited to, aluminum, magnesium-silver alloy, and aluminum-lithium alloy.
Examples of the material for forming the electron blocking layer include, but are not limited to, tris (phenylpyrazole) iridium.
Examples of the hole-transporting polymer include poly [ (9, 9-dihexylfluorene-2, 7-diyl) -co- (N, N '-bis { p-butylphenyl } -1, 4-diaminophenylene) ], poly [ (9, 9-dioctylfluorene-2, 7-diyl) -co- (N, N' -bis { p-butylphenyl } -1,1 '-biphenylene-4, 4-diamine) ], poly [ (9, 9-bis { 1' -penten-5 '-yl } fluorene-2, 7-diyl) -co- (N, N' -bis { p-butylphenyl } -1, 4-diaminophenylene) ], poly [ N ] terminated with polysilsesquioxane, n ' -bis (4-butylphenyl) -N, N ' -bis (phenyl) -benzidine ], poly [ (9, 9-dioctylfluorene-2, 7-diyl) -co- (4,4 ' - (N- (p-butylphenyl)) diphenylamine) ], and the like.
Examples of the light-emitting polymer include polyfluorene derivatives such as poly (9, 9-dialkylfluorene) (PDAF), polyphenylene vinylene derivatives such as poly (2-methoxy-5- (2' -ethylhexyloxy) -1, 4-phenylene vinylene) (MEH-PPV), polythiophene derivatives such as poly (3-alkylthiophene) (PAT), and polyvinylcarbazole (PVCz).
The charge-transporting varnish of the present invention is preferably used for forming a functional layer provided between an anode and a light-emitting layer, such as a hole injection layer, a hole transport layer, and a hole injection transport layer of an organic EL element, as described above, and can also be used for forming a charge-transporting thin film in an electronic element, such as an organic photoelectric conversion element, an organic thin film solar cell, an organic perovskite photoelectric conversion element, an organic integrated circuit, an organic electric field effect transistor, an organic thin film transistor, an organic light-emitting transistor, an organic optical detector, an organic light receiver, an organic electro-extinction element, a light-emitting electrochemical cell, a quantum dot light-emitting diode, a quantum laser, an organic laser diode, and an organic plasmon light-emitting element.
Examples
The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The apparatus used is as follows.
(1) MALDI-TOF-MS: autoflex III smartclaw manufactured by Bruker
(2)1H-NMR: JNM-ECP300 FT NMR SYSTEM manufactured by Japan electronics Co., Ltd
(3) Cleaning a substrate: substrate cleaning device (reduced pressure plasma method) manufactured by Changzhou industry
(4) Coating of varnish: ミカサ Kabushiki Kaisha spin coater MS-A100
(5) And (3) measuring the film thickness: SURFCORDER ET-4000 Fine shape measuring device manufactured by Okawa research
(6) And (3) manufacturing an element: multifunctional evaporation device system C-E2L1G1-N manufactured by Changzhou industry
(7) Measurement of current density and luminance of element: multi-channel IVL measuring device manufactured by EHC
(8) Life measurement (luminance half-life measurement) of EL element: organic EL Brightness Life evaluation System PEL-105S manufactured by EHC
(9) Measurement of refractive index (n) and extinction coefficient (k): woollam Japan manufactures multiple incident angle spectroscopic ellipsometer VASE
[1] Production of arylamine compound
[ example 1-1] Synthesis of arylamine Compound A
[ solution 19]
In a 4-neck flask were placed 0.3g of 3, 6-diaminocarbazole, 2.570g of 2-bromophenylcarbazole, and Pd2(dba)20.086g、[(tBu)3PH]BF40.087g, tBuONa1.05g and 10g of toluene, and stirred at 80 ℃ for 3 hours. Then, the temperature was returned to room temperature, and Celite filtration was performed. Toluene and saturated brine were added to the filtrate to separate the solution, and the aqueous layer was removed. Adding an appropriate amount of MgSO4And left to stand at room temperature for 10 minutes. MgSO (MgSO)4The filtrate was concentrated by filtration through silica gel. The obtained concentrated solution was dropped into a mixed solvent of ethyl acetate and methanol, and after stirring at room temperature for 30 minutes, the precipitated solid was separated by filtration. The obtained solid was dried to obtain 0.82g of arylamine compound a (yield 38%).
1H-NMR(500MHz，THF-d8)δ[ppm]：7.95-7.92(m，10H)，7.72-7.55(m，20H)，7.54-7.41(m，5H)，7.35-7.20(m，25H)，7.16-7.09(m，6H).
[ example 1-2] Synthesis of arylamine Compound B
[ solution 20]
In a 4-neck flask were placed 0.502g of 3, 6-diaminocarbazole, 4.441g of 3-bromophenylcarbazole, and Pd2(dba)20.037g、[(tBu)3PH]BF40.037g, tBuONa1.346g, and toluene 15g, stirred at 80 ℃ for 5.5 hours. After the reaction, Celite filtration was performed, and the target site was concentrated by silica gel chromatography. The active material was added to the concentrate, and after stirring at room temperature for 1 hour, the active carbon was removed by filtration through Celite. The obtained filtrate was dropped into a mixed solvent of ethyl acetate and methanol, and stirred at room temperature for 1 hour. The precipitated solid was separated by filtration, and the obtained solid was dried to obtain 3.50g of an arylamine compound B (yield 98%).
1H-NMR(500MHz，THF-d8)δ[ppm]：8.12-7.92(m，10H)，7.85-7.67(m，20H)，7.66-7.53(m，5H)，7.37-7.24(m，25H)，7.19-7.10(m，6H).
[2] Preparation of Charge-transporting varnish
[ example 2-1]
Arylamine compound a (0.027g) obtained in example 1-1 and arylsulfonate a (0.024g) represented by the following formula, which was synthesized according to the method described in international publication No. 2017/217455, were added to chloroform (10g), and dissolved by stirring at room temperature, and the resulting solution was filtered through a syringe filter having a pore size of 0.2 μm to obtain charge-transporting varnish a1.
[ solution 21]
[ examples 2-2]
A charge-transporting varnish B1 was obtained in the same manner as in example 2-1, except that the arylamine compound A was changed to the arylamine compound B obtained in example 1-2.
[ examples 2 to 3]
A charge-transporting varnish A2 was obtained in the same manner as in example 2-1, except that the amount of the arylamine compound A used was changed to 0.040 g.
[ examples 2 to 4]
A charge-transporting varnish B2 was obtained in the same manner as in example 2-2, except that the amount of the arylamine compound B used was changed to 0.040 g.
[3] Production of film and evaluation of film physical Properties
Example 3-1 and example 3-2
The varnishes obtained in examples 2-1 and 2-2 were applied to a quartz substrate by using a spin coater, and the resultant was dried at 120 ℃ for 1 minute under atmospheric firing, and then fired at 200 ℃ for 15 minutes under atmospheric firing, whereby a uniform thin film of 50nm was formed on the quartz substrate.
The obtained film-attached quartz substrate was used to measure the average refractive index n in the visible region and the average extinction coefficient k in the visible region at a wavelength of 400 to 800 nm. The results are shown in table 1.
[ Table 1]
Average refractive index n in visible region
Average extinction coefficient k in visible region
Example 3-1
1.71
0.014
Examples 3 to 2
1.66
0.062
As shown in Table 1, it is understood that the film obtained from the charge-transporting varnish of the present invention has a high refractive index and a low extinction coefficient.
[4] Production and characteristic evaluation of Hole Only Device (HOD)1
[ preparation of solution for Forming hole injection layer ]
0.137g of an aniline derivative represented by the formula (T) synthesized by the method described in International publication No. 2013/084664 and 0.271g of an arylsulfonic acid represented by the formula (N) synthesized by the method described in International publication No. 2006/025342 were dissolved in 6.7g of 1, 3-dimethyl-2-imidazolidinone in a nitrogen atmosphere. To the obtained solution were added 10g of cyclohexanol and 3.3g of propylene glycol in this order, followed by stirring to prepare a solution for forming a hole injection layer.
[ solution 22]
[ example 4-1]
As the ITO substrate, a glass substrate of 25 mm. times.25 mm. times.0.7 t having Indium Tin Oxide (ITO) patterned on the surface thereof at a film thickness of 150nm was used, and O was used before use2The plasma cleaning apparatus (150W, 30 seconds) removed impurities on the surface. Next, the solution for forming a hole injection layer prepared above was applied onto an ITO substrate by spin coating, and the ITO substrate was heated to 80 ℃ on a hot plate in the air, dried for 1 minute, and then heated and fired at 230 ℃ for 15 minutes to form a hole injection layer (film thickness: 30 nm).
Next, the charge-transporting varnish A2 obtained in example 2-3 was coated on the hole-injecting layer using a spin coater, and then fired at 130 ℃ for 10 minutes in an atmospheric air atmosphere to form a 40nm hole-transporting layer thin film.
On the surface, a deposition apparatus (degree of vacuum 1.0X 10) was used-5Pa) ofAn 80nm aluminum thin film was formed at 0.2 nm/sec, and a Hole Only Device (HOD) was obtained.
[ example 4-2]
An HOD was produced in the same manner as in example 4-1, except that the charge-transporting varnish B2 obtained in example 2-4 was used in place of the charge-transporting varnish A2.
For the HOD produced above, the current density at a drive voltage of 4V was measured. The results are shown in table 2.
[ Table 2]
Current Density (mA/cm)2)
Example 4-1
201
Example 4 to 2
282
As shown in table 2, it is understood that the film made of the charge-transporting varnish of the present invention exhibits excellent charge-transporting properties as a hole-transporting layer.
[5] Fabrication of Single Layer Devices (SLD)
[ example 5-1]
On an ITO substrate similar to that of example 4-1, charge-transporting varnish A1 obtained in example 2-1 was applied by means of a spin coater, dried at 120 ℃ for 1 minute under atmospheric firing, and then fired at 200 ℃ for 15 minutes under atmospheric firing to form a hole injection layer (film thickness: 50 nm).
On the surface, a deposition apparatus (degree of vacuum 1.0X 10) was used-5Pa) at 0.An 80nm aluminum thin film was formed at 2 nm/sec to obtain a Single Layer Device (SLD).
[ examples 5-2]
An SLD was produced in the same manner as in example 5-1, except that the charge-transporting varnish A2 obtained in example 2-2 was used in place of the charge-transporting varnish A1.
For the SLD prepared above, the current density at a drive voltage of 4V was measured. The results are shown in table 3.
[ Table 3]
Current Density (mA/cm)2)
Example 5-1
3110
Examples 5 and 2
4590
As shown in table 3, it is understood that the film made of the charge-transporting varnish of the present invention exhibits good charge-transporting properties.
[6] Production of HOD2
[ example 6-1]
On an ITO substrate similar to that of example 4-1, charge-transporting varnish A1 obtained in example 2-1 was applied by means of a spin coater, dried at 120 ℃ for 1 minute under the atmosphere, and then baked at 200 ℃ for 15 minutes to form a hole-injecting layer (film thickness: 50 nm).
On the surface, a deposition apparatus (degree of vacuum 2.0X 10) was used-5Pa) films of α -NPD and aluminum were laminated in this order to obtain HOD. At a deposition rate of 0.2nmVapor deposition was performed under the condition of seconds. The film thicknesses of the α -NPD and aluminum thin films were 30nm and 80nm, respectively.
[ example 6-2]
An HOD was produced in the same manner as in example 6-1, except that the charge-transporting varnish A2 obtained in example 2-2 was used in place of the charge-transporting varnish A1.
For the HOD produced above, the current density at a drive voltage of 4V was measured. The results are shown in table 4.
[ Table 4]
Current Density (mA/cm)2)
Example 6-1
171
Example 6 to 2
360
As shown in table 4, it is understood that the film made of the charge-transporting varnish of the present invention exhibits good hole injection properties into the hole-transporting layer as the hole-injecting layer.
[7] Production of organic EL element and evaluation of characteristics
[ example 7-1]
The charge-transporting varnish A1 obtained in example 2-1 was applied to the same ITO substrate as in example 4-1 using a spin coater, dried at 120 ℃ for 1 minute under the atmosphere, and then fired at 200 ℃ for 15 minutes to form a 50nm thin film.
Then, for the ITO substrate on which the thin film was formed, evaporation was usedPlating apparatus (vacuum degree 1.0X 10)-5Pa), an α -NPD film of 30nm was formed at 0.2 nm/sec. Next, a film of an electron-blocking material HTEB-01 manufactured by Kanto chemical Co., Ltd was formed at 10 nm. Next, a light-emitting layer host material NS60 and a light-emitting layer dopant material Ir (ppy) manufactured by Nissian electronics Co., Ltd3And (4) co-evaporation. For co-evaporation, Ir (ppy)3The deposition rate was controlled so that the concentration of (2) was 6%, and 40nm was stacked. Next, Alq is sequentially added3And thin films of lithium fluoride and aluminum were laminated to obtain an organic EL device. At this time, the deposition rate is set to Alq3And aluminum at 0.2 nm/sec, and lithium fluoride at 0.02 nm/sec, with film thicknesses of 20nm, 0.5nm, and 80nm, respectively.
In order to prevent deterioration of characteristics due to the influence of oxygen, water, and the like in the air, the characteristics of the organic EL element were evaluated after sealing the organic EL element with a sealing substrate. The sealing was performed as follows. The organic EL element was put between the sealing substrates in a nitrogen atmosphere having an oxygen concentration of 2ppm or less and a dew point of-76 ℃ or less, and the sealing substrates were bonded with an adhesive (MORCO MOISTURE CUT WB90US (P)). At this time, the water-capturing agent (HD-071010W-40 manufactured by ダイニック Co.) was contained in the sealing substrate together with the organic EL element. The pasted sealing substrate was irradiated with UV light (wavelength: 365nm, dose: 6000 mJ/cm)2) Thereafter, the adhesive was cured by annealing at 80 ℃ for 1 hour.
[ example 7-2]
An organic EL device was produced in the same manner as in example 7-1, except that the charge-transporting varnish a2 obtained in example 2-2 was used in place of the charge-transporting varnish a1.
The organic EL element thus obtained was measured at 5000cd/m2Driving voltage, current density, current efficiency, light emission efficiency, external light emission quantum yield (EQE), and LT85 (initial luminance 5000 cd/m) when the phosphor is made to emit light215% reduction in time). The results are shown in table 5.
[ Table 5]
As shown in table 5, it is understood that the organic EL elements of the present invention each showed high current efficiency and high EQE, and showed good life characteristics.