Charge-transporting varnish and charge-transporting varnish for quantum dot electroluminescent element

Abstract

Provided is a charge-transporting varnish that provides a charge-transporting thin film having excellent hole transport properties, and that comprises: a copper(I) halide or a copper(I) pseudo halide; one selected from the group consisting of amines represented by formulae (1)-(3); SiO2 nanoparticles; and a solvent. (In the formulae, R1-R4 each independently represent a hydrogen atom or an alkyl group having 1-6 carbon atoms. L represents an alkylene group having 3-8 carbon atoms, and the alkylene group optionally has an oxygen atom interposed between carbon atoms. At least three carbon atoms are interposed between H2N- and -OH. R5-R6 each independently represent an alkyl group that has 1-6 carbon atoms and is optionally substituted with a hydroxy group, and the alkyl group optionally has an oxygen atom interposed between carbon atoms. At least one alkyl group of R5 and R6 is substituted with a hydroxy group or has an oxygen atom interposed between carbon atoms.)

Description

Charge transport varnish and charge transport varnish for quantum dot electroluminescence device

[0001] The present invention relates to a charge transporting varnish and a charge transporting varnish for a quantum dot electroluminescent device.

[0002] In organic electroluminescence (hereinafter referred to as organic EL) devices, organic functional films made of organic compounds are used as the light-emitting layer and charge injection layer. In particular, the hole injection layer is responsible for transferring charges between the anode and the hole transport layer or light-emitting layer, and plays an important role in achieving low-voltage operation and high brightness of the organic EL device. In addition, the hole transport layer is responsible for transferring charges between the hole injection layer and the light-emitting layer, and plays an important role in achieving low-voltage operation and high brightness of the organic EL device.

[0003] Methods for forming hole injection layers and hole transport layers are roughly divided into dry processes, typified by vapor deposition, and wet processes, typified by inkjet methods and spin coating methods. Comparing these processes, wet processes can efficiently produce thin films with high flatness over large areas. Therefore, as organic EL displays are currently being made larger in area, hole injection layers and hole transport layers that can be formed by wet processes are desired, and technologies related to hole injection materials and hole transport materials that can be formed by wet processes have been reported (Patent Document 1).

[0004] Furthermore, in recent years, with the development of display technology, quantum dot electroluminescence (hereinafter referred to as quantum dot EL) devices, which use quantum dot materials as light-emitting layers, have emerged and are showing promise for a wide range of applications. These quantum dot EL devices can be manufactured at low cost using wet processes, and are attracting much attention in fields such as display technology and lighting due to their characteristics, such as controllability of emission wavelength, high color purity, high luminous efficiency, and flexibility.

[0005] However, in a wet process, when another functional layer, such as an emitting layer, is formed on a charge-transporting thin film, such as a hole-transporting layer, a portion of the thin film may be dissolved by the solvent of the varnish (composition) forming the other layer. In such cases, the resulting device may suffer from a decrease in hole transport properties, which is one of the causes of deterioration in device characteristics. Furthermore, when a functional layer is formed adjacent to the emitting layer, the resulting device may suffer from a decrease in photoluminescence (PL) intensity, a phenomenon known as PL quenching, and further improvement is desired.

[0006] Currently, there is a demand for improved performance of organic EL elements and quantum dot EL elements, and improvements are constantly being sought for wet process materials for hole injection layers and hole transport layers. In particular, there is an increasing demand for materials that can provide charge transport thin films with high hole injection or hole transport properties, as these materials can contribute to improved performance such as the luminance characteristics of organic EL elements and quantum dot EL elements.

[0007] International Publication No. 2008 / 032616

[0008] The present invention has been made in view of the above circumstances, and aims to provide a charge-transporting varnish that gives a thin film having practical charge-transporting properties (particularly, hole-injecting properties or hole-transporting properties) and also excellent solvent resistance.

[0009] The present inventors have conducted extensive research to solve the above problems and have found that a charge-transporting thin film having both practical charge transport properties and excellent solvent resistance can be obtained by using a charge-transporting varnish that combines copper halide (I) or pseudocopper halide (I), a specific amine, and SiO nanoparticles. Furthermore, they have found that the use of copper halide (I) or pseudocopper halide (I) and a specific amine in a charge-transporting varnish for quantum dot EL devices improves the solvent resistance of the thin film obtained using the varnish, thereby completing the present invention.

[0010] That is, the present invention provides the following charge-transporting varnish and charge-transporting varnish for quantum dot EL devices: 1. A charge-transporting varnish comprising copper(I) halide or pseudocopper(I) halide, one amine selected from the group consisting of amines represented by the following formulas (1) to (3), SiO2 nanoparticles, and a solvent. (In formula (1), R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L is an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between HN- and -OH. In formula (3), R 5 ~R 6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxy group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or an oxygen atom is present between the carbon atoms. 2. The charge transport varnish of 1, wherein the content of the amine is 1 to 40 moles per mole of copper(I) halide or pseudocopper(I) halide. 3. The charge transport varnish of 1 or 2, wherein the content of the copper(I) halide or pseudocopper(I) halide is 10 to 95 mass % of the solid content. 4. The charge transport varnish of any of 1 to 3, wherein the content of the SiO2 nanoparticles is 5 to 90 mass % of the solid content. 5. The charge transport varnish of any of 1 to 4, wherein the copper(I) halide or pseudocopper(I) halide is copper(I) halide or copper(I) thiocyanate. 6. The charge transport varnish of 5, wherein the copper(I) halide is copper(I) iodide. 7. The charge transport varnish of any of 1 to 6, wherein the amine is any of the amines represented by the following formula: 8. The charge-transporting varnish according to any one of 1 to 7, further comprising a compound represented by the following formula (X): (wherein A represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring having a carbon atoms constituting the ring; R xare groups bonded to carbon atoms constituting the ring, and each independently represents a hydroxy group, silanol group, thiol group, amino group, carboxy group, phosphate group, phosphate ester group, ester group, thioester group, amide group, sulfonamide group, nitro group, substituted or unsubstituted monovalent hydrocarbon group, organoxy group, organoamino group, organosilyl group, organothio group, acyl group, sulfo group, cyano group, chlorine atom, bromine atom, or iodine atom; a represents an integer satisfying 6≦a when A is an aromatic hydrocarbon ring, or an integer satisfying 1≦a when A is an aromatic heterocycle; m represents an integer satisfying 1≦m≦a; n represents an integer satisfying 0≦n≦a-1; p represents an integer satisfying 0≦p≦a-1, and m+n+p≦a. 9. The charge-transporting varnish of 8, wherein A is an aromatic hydrocarbon ring. 10. 11. The charge transporting varnish of 9, wherein A is a benzene ring. x are each independently a thiol group, an amino group, or an organothio group. 12. A charge transport varnish according to any one of 8 to 11, wherein the content of the compound represented by formula (X) is 0.1 to 2.0 mol per mol of the copper(I) halide or pseudocopper(I) halide. 13. A charge transport thin film obtained from the charge transport varnish according to any one of 1 to 12. 14. An electronic device comprising the charge transport thin film of 13. 15. The electronic device of 14, wherein the charge transport thin film is a hole injection layer, a hole transport layer, or a hole injection transport layer. 16. The electronic device of 15, wherein the electronic device is an organic EL device or a quantum dot EL device. 17. A charge transport varnish for a quantum dot EL device, comprising copper(I) halide or pseudocopper(I) halide, one amine selected from the group consisting of amines represented by the following formulas (1) to (3), and a solvent. (In formula (1), R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L is an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between HN- and -OH. In formula (3), R 5 ~R6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxy group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or has an oxygen atom between the carbon atoms.

[0011] By using the charge transport varnish of the present invention, a charge transport thin film can be obtained that combines practical charge transport properties (particularly hole injection properties and hole transport properties) with excellent solvent resistance. This charge transport thin film can be suitably used as a thin film for electronic devices, such as organic EL devices and quantum dot EL devices. In particular, when the charge transport varnish of the present invention is used to form a hole transport layer for an organic EL device or a quantum dot EL device, the hole transport properties to the light-emitting layer formed thereon are improved, thereby improving the luminance characteristics, etc., of the device. Furthermore, the resulting thin film has excellent solvent resistance and can suppress the occurrence of PL quenching, etc., in the resulting device, thereby improving its characteristics and quality. Furthermore, by using the charge transport varnish for quantum dot EL devices of the present invention, a charge transport thin film can be obtained that combines practical charge transport properties (particularly hole injection properties and hole transport properties) with excellent solvent resistance. In particular, when the charge transport varnish of the present invention is used to form a hole transport layer for a quantum dot EL device, the hole transport properties to the light-emitting layer formed thereon are improved, thereby improving the luminance characteristics, etc., of the device. Furthermore, the thin film obtained has excellent solvent resistance, which is expected to improve the characteristics and quality of elements manufactured by wet processes.

[0012] Fluorescence spectra obtained for photoluminescence (PL) evaluation substrates prepared in Examples 4-1 and 4-2 and Comparative Example 4-1. FIG. 5 is a diagram showing the results of measuring the film absorbance of the toluene-treated substrate and the toluene-untreated substrate prepared in Example 5-1. FIG. 6 is a diagram showing the results of measuring the film absorbance of the toluene-treated substrate and the toluene-untreated substrate prepared in Example 5-2. FIG. 7 is a diagram showing the results of measuring the film absorbance of the toluene-treated substrate and the toluene-untreated substrate prepared in Comparative Example 5-1. FIG. 8 is a diagram showing the results of measuring the film absorbance of the toluene-treated substrate and the toluene-untreated substrate prepared in Comparative Example 5-2.

[0013] The present invention will be described in more detail below. The charge-transporting varnish according to the present invention is characterized by comprising copper(I) halide or pseudocopper(I) halide, one amine selected from the group consisting of amines represented by the following formulas (1) to (3), SiO nanoparticles, and a solvent. In the present invention, charge transportability is synonymous with conductivity, hole injection property, and hole transportability. The charge-transporting varnish may itself have charge transportability, or the solid film obtained from it may have charge transportability. In the present invention, the solid content refers to components other than the solvent contained in the charge-transporting varnish. However, the amine and compound represented by formula (X), which will be described later, are not included in the solid content.

[0014] [1] Copper(I) halide or pseudocopper(I) halide Copper(I) halide is a compound consisting of copper ion(I) and its counter anion, a halide ion. The halide ion can be a fluoride ion (F - ), chloride ions (Cl - ), bromide ion (Br - ), iodide ion (I - Specific examples of copper(I) halides include copper(I) fluoride (CuF), copper(I) chloride (CuCl), copper(I) bromide (CuBr), and copper(I) iodide (CuI). These copper(I) halides may be used alone or in combination of two or more.

[0015] Pseudocopper(I) halides are compounds consisting of copper(I) ions and their counter anions, pseudohalide ions. The pseudohalide ions are a general term for anions that exhibit properties similar to halogen atoms, and specific examples include thiocyanate ions (SCN - ), cyano ion (CN - ), cyanate ion (NCO - ), isocyanate ion (OCN - ) Selenocyanic acid (SeCN - ), azide ion (N - ) and the like. Specific examples of pseudo copper(I) halides include copper(I) thiocyanate (CuSCN), copper(I) cyanide (CuCN), copper(I) isocyanate (CuOCN), copper(I) selenocyanate (CuSeCN), copper(I) azide (CuN3), and the like. These pseudo copper(I) halides may be used alone or in combination of two or more.

[0016] In the present invention, among the above copper(I) halides and pseudocopper(I) halides, copper(I) halide or copper(I) thiocyanate is preferred, and copper(I) iodide is more preferred, from the viewpoint of the charge transport property and solvent resistance of the resulting thin film.

[0017] The content of the copper(I) halide or pseudocopper(I) halide is preferably 10 to 70 mass %, more preferably 30 to 70 mass %, and even more preferably 40 to 60 mass %, of the solid content, from the viewpoint of the charge transport property and solvent resistance of the resulting thin film.

[0018] Copper(I) halide and pseudocopper(I) halide may be used in combination, and in this case, it is preferable to use copper(I) iodide and copper(I) thiocyanate in combination. In this case, the content of pseudocopper(I) halide is preferably 0.1 to 2.0 mol, more preferably 0.2 to 1.0 mol, and even more preferably 0.3 to 0.7 mol per mol of copper(I) halide.

[0019] [2] Amine The charge-transporting varnish of the present invention contains one amine selected from the group consisting of amines represented by the following formulas (1) to (3). In the present invention, the use of these amines can increase the solubility of the copper(I) halide and pseudocopper(I) halide in a solvent.

[0020]

[0021] In formula (1), R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L is an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between HN- and -OH. In formula (3), R 5 ~R 6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxy group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or has an oxygen atom between the carbon atoms.

[0022] Examples of the 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 i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group.

[0023] Examples of the alkylene group having 3 to 8 carbon atoms (which satisfies the amine structure represented by the formula (2)) include a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

[0024] In the above formula (1), R 1 ~R 4 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably contains at least one hydrogen atom and at least one alkyl group.

[0025] Specific examples of the amine represented by the above formula (1) include, but are not limited to, those represented by the following formulas (1-1) to (1-5). Among these, those represented by the following formulas (1-1) and (1-2) are preferred.

[0026]

[0027] In the above formula (2), L is preferably an alkylene group having 4 to 6 carbon atoms, more preferably a tetramethylene group, a pentamethylene group, or a hexamethylene group.

[0028] Specific examples of the amine represented by the formula (2) include, but are not limited to, those represented by the following formulas (2-1) and (2-2). Among these, the amine represented by the following formula (2-1) is preferred.

[0029]

[0030] In the above formula (3), R 5 ~R 6 The alkyl group in R is preferably an alkyl group having 3 to 5 carbon atoms. 5 and R 6 Preferably, both alkyl groups in the above are substituted with a hydroxy group or an oxygen atom is present between the carbon atoms, and more preferably an oxygen atom is present between the carbon atoms.

[0031] Specific examples of the amine represented by the above formula (3) include, but are not limited to, those represented by the following formula (3-1):

[0032]

[0033] The content of the amine is usually, taking into consideration the solubility of the copper(I) halide or pseudocopper(I) halide, and is preferably 1 to 40 moles, more preferably 1 to 10 moles, even more preferably 2 to 8 moles, and still more preferably 3 to 7 moles per mole of the copper(I) halide or pseudocopper(I) halide. As mentioned above, the amine is not included in the solid content.

[0034] [3] SiO2 nanoparticles The charge-transporting varnish of the present invention contains SiO2 nanoparticles. Note that nanoparticles refer to fine particles whose primary particle average particle diameter is on the order of nanometers (typically 500 nm or less). SiO2 nanoparticles refer to SiO2 formed into nanoparticles.

[0035] In the present invention, the primary particle size of the SiO nanoparticles is not particularly limited as long as it is nano-sized, but is usually 5 nm or more, and from the viewpoint of ensuring good particle dispersibility, ease of production, etc., it is usually 200 nm or less, preferably 100 nm or less, and more preferably 30 nm or less.

[0036] In the present invention, the SiO2 nanoparticles may be surface-treated with a silane coupling agent, such as, but not limited to, the silane coupling agent represented by the following formula (S1):

[0037]

[0038] In formula (S1), R v1 ~R v3 each independently represents a hydrogen atom, a chlorine atom, a hydroxy group, an alkoxy group which may have a substituent, or an alkyl group which may have a substituent; R v1 ~R v3 At least one of L represents a hydrogen atom, a chlorine atom, a hydroxy group or an alkoxy group which may have a substituent; s represents a single bond or an alkylene group having 1 to 10 carbon atoms; R v4 represents an alkyl group having 1 to 10 carbon atoms which may have at least one substituent selected from the group consisting of a halogen atom, a sulfo group, and a hydroxy group; an alkoxy group having 1 to 10 carbon atoms which may have at least one substituent selected from the group consisting of a halogen atom, a sulfo group, and a hydroxy group; or an aryl group having 6 to 20 carbon atoms which may have at least one substituent selected from the group consisting of a halogen atom, a sulfo group, a hydroxy group, an alkyl group having 1 to 10 carbon atoms, and an alkoxy group having 1 to 10 carbon atoms.

[0039] R v1 ~R v3 The alkoxy group may have a linear, branched, or cyclic alkyl group, and specific examples thereof include alkoxy groups having 1 to 10 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptyloxy, n-octyloxy, n-nonyloxy, and n-decyloxy groups. Alkoxy groups having 1 to 5 carbon atoms are preferred, alkoxy groups having 1 to 3 carbon atoms are more preferred, and methoxy and ethoxy groups are even more preferred.

[0040] R v1 ~R v3 The alkyl group may be either linear or branched, and specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as 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. Alkyl groups having 1 to 5 carbon atoms are preferred, alkyl groups having 1 to 3 carbon atoms are more preferred, and methyl, ethyl, and n-propyl groups are even more preferred.

[0041] The above R v1 ~R v3 may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an amino group, and an organosilyl group. v1 ~R v3 When has a substituent, the number of the substituents is preferably 1 to 6, and more preferably 1 to 3.

[0042] Examples of halogen atoms include fluorine, chlorine, bromine and iodine atoms, with fluorine atoms being preferred.

[0043] Examples of organosilyl groups include trialkylsilyl groups in which each alkyl group has 1 to 10 carbon atoms, such as trimethylsilyl group, triethylsilyl group, tripropylsilyl group, tributylsilyl group, tripentylsilyl group, trihexylsilyl group, pentyldimethylsilyl group, hexyldimethylsilyl group, octyldimethylsilyl group, and decyldimethylsilyl group. Other examples include trialkoxysilyl groups in which each alkoxy group has 1 to 10 carbon atoms, such as trimethoxysilyl group, triethoxysilyl group, tri-n-propoxysilyl group, triisopropoxysilyl group, tri-n-butoxysilyl group, tri-s-butoxysilyl group, tri-t-butoxysilyl group, tri-n-pentoxysilyl group, tri-n-hexyloxysilyl group, tri-n-octyloxysilyl group, and tri-n-decyloxysilyl group.

[0044] L s The alkylene group having 1 to 10 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a nonamethylene group, and a decylene group. Among these, an alkylene group having 2 to 5 carbon atoms is preferred, an alkylene group having 2 to 4 carbon atoms is more preferred, and an ethylene group, a trimethylene group, or a tetramethylene group is even more preferred.

[0045] R v4 Examples of the halogen atom include the same as those exemplified above.

[0046] R v4The alkyl group having 1 to 10 carbon atoms may be either linear or branched, and specific examples thereof 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, a tert-butyl group, an n-pentyl group, a cyclopentyl group, a 4-methylpentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, and the like. An alkyl group having 1 to 8 carbon atoms is preferred, an alkyl group having 1 to 6 carbon atoms is more preferred, and a methyl group, an ethyl group, an n-propyl group, or a 4-methylpentyl group is even more preferred.

[0047] R v4 The alkoxy group having 1 to 10 carbon atoms may have a linear, branched, or cyclic alkyl group, and specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, an n-hexoxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group. An alkoxy group having 1 to 5 carbon atoms is preferred, an alkoxy group having 1 to 3 carbon atoms is more preferred, and a methoxy group, an ethoxy group, or an n-propoxy group is even more preferred.

[0048] R v4 Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a tolyl 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, a 2-phenanthryl group, a 3-phenanthryl group, a 4-phenanthryl group, and a 9-phenanthryl group, with a phenyl group, a tolyl group, and a naphthyl group being preferred.

[0049] R v4 Examples of the alkyl group having 1 to 10 carbon atoms and the alkoxy group having 1 to 10 carbon atoms contained in the aryl group having 6 to 20 carbon atoms include the same groups as those exemplified above.

[0050] The above R v4 When has a substituent, the number of the substituents is preferably 1 to 10, and more preferably 1 to 7.

[0051] However, in the above formula (S1), R v4 is an alkyl group having 1 to 10 carbon atoms which may have a substituent, when L s is a single bond.

[0052] As the silane coupling agent represented by the formula (S1), in consideration of the charge transporting property of the resulting charge transporting thin film, v1 ~R v3 is preferably an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, or a hydroxy group; an alkyl group having 1 to 5 carbon atoms which may have a substituent or an alkoxy group having 1 to 5 carbon atoms which may have a substituent is more preferred; an alkyl group having 1 to 3 carbon atoms which may have a substituent or an alkoxy group having 1 to 3 carbon atoms which may have a substituent is even more preferred; and a methyl group, an ethyl group, a methoxy group, or an ethoxy group is even more preferred.

[0053] In addition, the above R v1 ~R v3 Among these, at least one of which is an alkoxy group having 1 to 10 carbon atoms which may have a substituent, is preferred, and at least one of which is an alkoxy group having 1 to 5 carbon atoms which may have a substituent is even more preferred.

[0054] Specific examples of the silane coupling agent represented by the above formula (S1) include, for example, trimethoxy(methyl)silane, trimethoxy(3-methoxypropyl)silane, trimethoxy(propyl)silane, trimethoxy(4-methoxyphenyl)silane, trimethoxyphenylsilane, methoxytrimethylsilane, [3-(1,1,2,3,3,3-hexafluoropropoxy)propyl]trimethoxysilane, trifluoropropyltrimethoxysilane, 1,1,1-trifluoro-2-(trifluoromethyl)-5-(trimethoxysilyl)pentan-2-ol, trimethoxy[3-(perfluorophenyl)propyl]silane, Examples of the silane include trimethoxyphenylsilane, ethoxytriethylsilane, methoxydimethyl(phenyl)silane, pentafluorophenylethoxydimethylsilane, trimethylethoxysilane, diethoxydimethylsilane, dimethoxydimethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, diethoxy(methyl)phenylsilane, triethoxyethylsilane, decyltrimethoxysilane, ethyltrimethoxysilane, hexyltriethoxysilane, hexyltrimethoxysilane, triethoxymethylsilane, n-octyltriethoxysilane, and 3-(trihydroxysilyl)-propanesulfonic acid.

[0055] Among these, trimethoxy(methyl)silane, trimethoxy(3-methoxypropyl)silane, trimethoxy(propyl)silane, trimethoxy(4-methoxyphenyl)silane, trimethoxyphenylsilane, methoxytrimethylsilane, [3-(1,1,2,3,3,3-hexafluoropropoxy)propyl]trimethoxysilane, trifluoropropyltrimethoxysilane, 1,1,1-trifluoro-2-(trifluoromethyl)-5-(trimethoxysilyl)pentan-2-ol, and trimethoxy[3-(perfluorophenyl)propyl]silane are particularly preferred in the present invention.

[0056] The silane coupling agent may be a commercially available product, or may be obtained by reacting various allyl compounds with a metal catalyst using a known method of hydrosilylation (for example, see Non-Patent Document RSC Adv., 2015, 20603-20616).

[0057] In the present invention, the primary particle size of the SiO nanoparticles constituting the surface-treated SiO nanoparticles is not particularly limited as long as it is nano-sized, but is usually 5 nm or more, and from the viewpoint of ensuring good particle dispersibility, ease of production, etc., it is usually 200 nm or less, preferably 100 nm or less, and more preferably 30 nm or less.

[0058] The primary particle diameter of the surface-treated SiO nanoparticles is not particularly limited, but is usually 5 nm or more, and from the viewpoint of ensuring good particle dispersibility and ease of production, it is usually 200 nm or less, preferably 100 nm or less, and more preferably 30 nm or less. This particle diameter is the particle diameter at which the cumulative frequency distribution in volume-based particle size distribution measurement by dynamic light scattering method becomes 50% (median diameter D 50 )

[0059] In the surface-treated SiO nanoparticles used in the present invention, the amount of silane coupling agent modified on the surface of the SiO nanoparticles is not particularly limited. However, from the viewpoint of the dispersibility of the SiO nanoparticles and the transparency of the resulting thin film, it is preferable that the amount be 0.1 particles / nm or more and 4.0 particles / nm or less. 2 Preferably, it is less than 0.2 to 2.9 particles / nm 2 More preferably, 0.3 to 2.0 particles / nm 2 It is more preferable that the modification amount X (number / nm 2 ) are the particle size (nm) and specific gravity (g / cm) of the SiO2 nanoparticles 3 ) The specific surface area SA (nm 2 / g), the total amount of metal oxide particles M (g), the molecular weight Mw of the silane coupling agent, the amount Y (g) of the silane coupling agent, and Avogadro's constant L, and the value is calculated as Y = X * SA * M * Mw / L.

[0060] The content of the SiO nanoparticles or surface-treated SiO nanoparticles contained in the charge-transporting varnish of the present invention is not particularly limited, but from the viewpoint of improving the hole transport property of the obtained thin film, enhancing the uniformity of the film, etc., the content is preferably 5 to 90 mass % of the solid content, more preferably 30 to 90 mass %, even more preferably 40 to 80 mass %, and even more preferably 50 to 70 mass %.

[0061] The SiO2 nanoparticles or surface-treated SiO2 nanoparticles used in the present invention may be used in the form of a sol dispersed in a dispersion medium, such as methanol, methyl ethyl ketone, methyl isobutyl ketone, N,N-dimethylacetamide, ethylene glycol, isopropanol, methanol, ethylene glycol monopropyl ether, diethylene glycol monoisobutyl ether, dipropylene glycol monomethyl ether, cyclohexanone, ethyl acetate, toluene, propylene glycol monomethyl ether acetate, triethylene glycol monobutyl ether, or triethylene glycol butyl methyl ether.

[0062] The solids concentration of the sol is not particularly limited, but is preferably 5 to 60% by mass, more preferably 5 to 50% by mass, and even more preferably 5 to 35% by mass. The amount of sol used is determined appropriately taking the concentration into consideration so that the amount of surface-treated SiO nanoparticles finally contained in the varnish will be the blending amount of the SiO nanoparticles described above.

[0063] [4] Solvent The charge transporting varnish of the present invention contains a solvent. The solvent is not particularly limited as long as it disperses or dissolves the solid content. Specific examples include water; alcoholic solvents such as methanol, ethanol, n-propanol, i-propanol, n-butanol, 1-octanol, 1-nonanol, 1-decanol, tetrahydrofurfuryl alcohol, terpineol, cyclohexanol, diacetone alcohol, benzyl alcohol, 2-phenoxyethanol, and 2-benzyloxyethanol; ethylene glycol, propylene glycol, 2-methyl-2,4-pentanediol, 1,3-octylene glycol, diethylene glycol, and dipropylene glycol. Glycol-based solvents such as glycol, triethylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, and 3-methyl-1,5-pentanediol; ketone-based solvents such as acetone, acetylacetone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, 4-hydroxy-4-methyl-2-pentanone, 2-heptanone, cyclohexanone, methylcyclopentanone, and isophorone;Dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, isobutyl acetate, n-hexyl acetate, benzyl acetate, 2-hydroxyethyl acetate, methyl lactate, ethyl lactate, methyl propionate, ethyl propionate, propyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dimethyl adipate, diethyl adipate, dipropyl adipate, diisopropyl malonate, dimethyl sebacate, diethyl sebacate, methyl benzoate, ethyl benzoate, butyl benzoate, dimethyl phthalate, dioxalate Ester-based solvents such as ethyl acetate, dibutyl oxalate, diethyl fumarate, ethylene glycol monomethyl ether acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, 1,3-butylene glycol diacetate, 1,6-hexanediol diacetate, triacetin, and γ-butyrolactone; ether-based solvents such as dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, anisole, and 4-methoxytoluene;Ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol diglycidyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-tert-butyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol butyl ether, etc. glycol ether solvents; amide solvents such as N-methylformamide, N-methylacetamide, N-methylformanilide, N,N-dimethylacetamide, N,N-dimethylformamide, N,N-dimethylisobutyramide, N-methyl-2-pyrrolidone, N-ethylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone; aromatic or halogenated aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, cyclohexylbenzene, chlorobenzene, tetralin, and decylbenzene; aliphatic hydrocarbon solvents such as n-hexane, n-heptane, n-octane, n-nonane, n-decane, i-octane, i-nonane, and i-decane; halogenated hydrocarbon solvents such as methylene chloride, dichloromethane, 1,2-dichloroethane, and chloroform; and cyano solvents such as acetonitrile and 3-methoxypropionitrile.Examples of the solvent include sulfoxide solvents such as dimethyl sulfoxide, and any of these may be appropriately selected and used. In the present invention, among these, alcohol solvents, glycol solvents, ketone solvents, ester solvents, and glycol ether solvents are preferred, and methanol, ethanol, 1-octanol, 1-nonanol, 1-decanol, terpineol, ethylene glycol, propylene glycol, 2-methyl-2,4-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 3-methyl-1,5-pentanediol, isophorone, propylene carbonate, dibutyl maleate, diethyl sebacate, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-tert-butyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol butyl ether are more preferred. These organic solvents can be used alone or in combination of two or more.

[0064] Furthermore, when forming a thin film using a charge-transporting varnish, a composition that ensures a uniform film thickness is required. In particular, when forming a film using an inkjet method, a composition containing only a low-boiling-point solvent may make it difficult to obtain a flat layer depending on the conditions of use. In such cases, the use of a high-boiling-point solvent is thought to suppress solvent evaporation and reduce the rate of ink convection and viscosity increase, thereby resulting in a flat layer. In consideration of this, among the above-mentioned organic solvents, it is preferable to contain at least one organic solvent having a boiling point of 200°C or higher, and more preferably at least one organic solvent having a boiling point of 230°C or higher. The upper limit of the boiling point is not particularly limited, but is usually 330°C or lower. When an organic solvent having a boiling point of 200°C or higher is included, its content is not particularly limited, but is preferably 20% by mass or higher in the organic solvent.

[0065] The charge-transporting varnish of the present invention is best prepared using only an organic solvent as the solvent. In this case, "only an organic solvent" means that only an organic solvent is used as the solvent, and does not exclude the presence of trace amounts of water contained in the organic solvent or solids used.

[0066] [5] Compound Represented by Formula (X) The charge-transporting varnish of the present invention may further contain a compound represented by the following formula (X). By containing this compound, further improvement in the charge transport properties of the resulting charge-transporting thin film can be expected. In particular, when a charge-transporting varnish containing a compound represented by formula (X) is used to form a hole-injection layer of an organic EL device or a quantum dot EL device, hole injection properties into the hole-transporting layer formed thereon are improved, and improvement in the luminance characteristics of the device is expected.

[0067]

[0068] In the formula, A represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring having a carbon atoms constituting the ring, and R x are groups bonded to carbon atoms constituting the ring, and each independently represents a hydroxy group, a silanol group, a thiol group, an amino group, a carboxy group, a phosphate group, a phosphate ester group, an ester group, a thioester group, an amide group, a sulfonamide group, a nitro group, a substituted or unsubstituted monovalent hydrocarbon group, an organooxy group, an organoamino group, an organosilyl group, an organothio group, an acyl group, a sulfo group, a cyano group, a chlorine atom, a bromine atom, or an iodine atom; when A is an aromatic hydrocarbon ring, a represents an integer that satisfies 6≦a; and when A is an aromatic heterocycle, a represents an integer that satisfies 1≦a; m represents an integer that satisfies 1≦m≦a; n represents an integer that satisfies 0≦n≦a-1; and p represents an integer that satisfies 0≦p≦a-1, and m+n+p≦a.

[0069] Examples of the aromatic hydrocarbon ring represented by A include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, and a perylene ring. In the present invention, a benzene ring is preferred.

[0070] Examples of the aromatic heterocycle represented by A include a triazole ring, a tetrazole ring, a pyrazole ring, an imidazole ring, a pyrrole ring, a pyridine ring, a furan ring, a thiophene ring, an indole ring, a benzofuran ring, a benzothiophene ring, a quinoline ring, and an isoquinoline ring.

[0071] The above R x Examples of the substituted or unsubstituted monovalent hydrocarbon group represented by the formula (I) include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-hexyl, n-octyl, 2-ethylhexyl, and decyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; bicycloalkyl groups such as bicyclohexyl; alkenyl groups such as vinyl, 1-propenyl, 2-propenyl, isopropenyl, 1-methyl-2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, and hexenyl; aryl groups such as phenyl, xylyl, tolyl, biphenyl, and naphthyl; and aralkyl groups such as benzyl, phenylethyl, and phenylcyclohexyl, as well as groups in which some or all of the hydrogen atoms have been further substituted with substituents such as halogen atoms, cyano, nitro, carboxy, sulfo, and hydroxyl. In the present invention, methyl, ethyl, n-propyl, n-butyl and phenyl groups are preferred.

[0072] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0073] The above R x Examples of the organoxy group represented by the formula (I) include an alkoxy group, an alkenyloxy group, an aryloxy group, etc. Examples of the alkyl group, alkenyl group, and aryl group contained therein are the same as those described above.

[0074] The above R xExamples of the organoamino group represented by the formula (I) include alkylamino groups having 1 to 12 carbon atoms, such as methylamino, ethylamino, propylamino, butylamino, pentylamino, hexylamino, cyclohexylamino, heptylamino, octylamino, nonylamino, decylamino, and dodecylamino; dialkylamino groups in which each alkyl group has 1 to 12 carbon atoms, such as dimethylamino, diethylamino, dipropylamino, dibutylamino, dipentylamino, dihexylamino, dicyclohexylamino, diheptylamino, dioctylamino, dinonylamino, and didecylamino; and morpholino groups. Furthermore, some or all of the hydrogen atoms of the alkyl group contained in the organoamino group may be substituted with halogen atoms. Examples of halogen atoms include the same as those exemplified above.

[0075] The above R x Examples of the organosilyl group represented by the formula (I) include trialkylsilyl groups in which the alkyl group has 1 to 10 carbon atoms, such as trimethylsilyl, triethylsilyl, tripropylsilyl, tributylsilyl, tripentylsilyl, trihexylsilyl, pentyldimethylsilyl, hexyldimethylsilyl, octyldimethylsilyl, and decyldimethylsilyl. The alkyl group contained in the organosilyl group may have some or all of its hydrogen atoms substituted with halogen atoms. Examples of the halogen atom include the same as those exemplified above.

[0076] The above R x Examples of the organothio group represented by the formula (I) include alkylthio groups having 1 to 12 carbon atoms, such as methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, octylthio, nonylthio, decylthio, and dodecylthio; and arylthio groups having 6 to 20 carbon atoms, such as phenylthio and naphthylthio. The alkyl and aryl groups contained in the organothio group may have some or all of their hydrogen atoms substituted with halogen atoms. Examples of halogen atoms include the same as those exemplified above.

[0077] The above R x As the group, a thiol group, an amino group and an organothio group are preferred.

[0078] When A is an aromatic hydrocarbon ring, the above-mentioned a is preferably 6≦a≦20, more preferably 6≦a≦14, and even more preferably 6≦a≦10. When A is an aromatic heterocycle, it is preferably 1≦a≦19, more preferably 1≦a≦13, and even more preferably 1≦a≦9.

[0079] The above m, n, and p preferably satisfy the following relationships: 1≦m≦a−1, 1≦n≦a−1, 0≦p≦a−2, and m+n+p≦a.

[0080] Specific examples of the compound represented by the above formula (X) include, but are not limited to, compounds represented by the following formulas (X1) to (X4).

[0081]

[0082] When the compound represented by formula (X) is contained, the content thereof is preferably 0.1 to 2.0 mol, more preferably 0.2 to 1.8 mol, and even more preferably 0.4 to 1.5 mol per mol of copper halide (I) or pseudocopper halide (I) from the viewpoint of improving device performance. Note that, as mentioned above, the compound represented by formula (X) is not included in the solid content.

[0083] Even when the compound represented by formula (X) is contained, copper(I) halide and copper(I) pseudohalide can be used in combination as the copper(I) halide or pseudohalide, and in this case, it is preferable to use copper(I) iodide and copper(I) thiocyanate in combination.

[0084] [6] Charge-Transporting Varnish and Charge-Transporting Thin Film The viscosity of the charge-transporting varnish is determined appropriately depending on the thickness of the thin film to be produced and the solid content concentration, but is usually 1 to 50 mPa·s at 25°C.

[0085] The solids concentration of the charge-transporting varnish is determined appropriately taking into consideration the viscosity and surface tension of the varnish, the thickness of the thin film to be produced, and the like, but is usually about 0.1 to 10.0 mass %, and in consideration of improving the coatability of the varnish, it is preferably about 0.5 to 8.0 mass %, and more preferably about 1.0 to 6.0 mass %.

[0086] The method for preparing the charge-transporting varnish is not particularly limited, but examples thereof include a method in which copper(I) halide or pseudocopper(I) halide and an amine are dissolved in a solvent, and SiO nanoparticles or surface-treated SiO nanoparticles or the like are added thereto.

[0087] In particular, when preparing a charge-transporting varnish, from the viewpoint of obtaining a thin film with higher flatness with good reproducibility, it is desirable to dissolve or disperse copper(I) halide or pseudocopper(I) halide, an amine, SiO nanoparticles or surface-treated SiO nanoparticles in an organic solvent, and then filter the resulting solution using a submicrometer-order filter or the like before use.

[0088] The charge-transporting varnish described above can be used to easily produce a charge-transporting thin film, and is therefore suitable for use in producing electronic devices, particularly organic EL devices and quantum dot EL devices. In this case, the charge-transporting thin film can be formed by applying the charge-transporting varnish described above to a substrate and baking it. The method for applying the varnish is not particularly limited, and examples include dipping, spin coating, transfer printing, roll coating, brush coating, inkjet coating, spraying, and slit coating. It is preferable to adjust the viscosity and surface tension of the varnish depending on the application method.

[0089] The atmosphere in which the charge transporting varnish is baked after application is not particularly limited.

[0090] The baking temperature is appropriately determined within a range of about 100 to 260° C., taking into consideration the use of the resulting thin film, the degree of charge transport property to be imparted to the resulting thin film, the type and boiling point of the solvent, etc. For example, when the resulting thin film is used as a hole transport layer of an organic EL device or a quantum dot EL device, the baking temperature is preferably about 140 to 250° C., and more preferably about 145 to 230° C. During baking, the temperature may be changed in two or more stages for the purpose of achieving more uniform film formation or promoting a reaction on the substrate, and heating may be performed using an appropriate device such as a hot plate or an oven.

[0091] The thickness of the charge transport thin film is not particularly limited, but is preferably 20 to 300 nm when used as a functional layer provided between an anode and a light-emitting layer, such as a hole injection layer, hole transport layer, or hole injection transport layer, of an organic EL device or a quantum dot EL device. Methods for changing the film thickness include changing the solids concentration in the varnish or changing the amount of solution on the substrate during application.

[0092] [7] Organic EL Devices and Quantum Dot EL Devices When the above-described charge transport thin film is applied to an organic EL device or a quantum dot EL device, the organic EL device or the quantum dot EL device can be configured to include the above-described charge transport thin film between a pair of electrodes constituting the organic EL device or the quantum dot EL device. Representative configurations of organic EL devices or quantum dot EL devices include, but are not limited to, the following (a) to (f). In the configurations described below, an electron blocking layer or the like can be provided between the light-emitting layer and the anode, and a hole blocking layer or the like can be provided between the light-emitting layer and the cathode, as necessary. Furthermore, the hole injection layer, the hole transport layer, or the hole injection transport layer may also function as an electron blocking layer, and the electron injection layer, the electron transport layer, or the electron injection transport layer may also function as a hole blocking layer. Furthermore, an optional functional layer can be provided between each layer 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 / 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 / hole injection layer / hole transport layer / light-emitting layer / cathode (f) anode / hole injection transport layer / light-emitting layer / cathode

[0093] The terms "hole injection layer," "hole transport layer," and "hole injection transport layer" refer to layers formed between the light-emitting layer and the anode, which have the function of transporting holes from the anode to the light-emitting layer. When only one layer of a hole-transporting material is provided between the light-emitting layer and the anode, it is the "hole injection transport layer." When two or more layers of a hole-transporting material are provided between the light-emitting layer and the anode, the layer closest to the anode is the "hole injection layer," and the remaining layers are "hole transport layers." In particular, the hole injection (transport) layer is a thin film that is excellent not only in the ability to accept holes from the anode but also in the ability to inject holes into the hole transport (light-emitting) layer.

[0094] The terms "electron injection layer," "electron transport layer," and "electron injection transport layer" refer to layers formed between the light-emitting layer and the cathode, which transport electrons from the cathode to the light-emitting layer. When only one layer of an electron-transporting material is provided between the light-emitting layer and the cathode, it is the "electron injection transport layer." When two or more layers of an electron-transporting material are provided between the light-emitting layer and the cathode, the layer closest to the cathode is the "electron injection layer," and the remaining layers are "electron transport layers." The term "light-emitting layer" refers to an organic layer that emits light. When a doping system is employed, it contains a host material and a dopant material. In this case, the host material primarily promotes the recombination of electrons and holes and confines excitons within the light-emitting layer, while the dopant material efficiently emits the excitons obtained by recombination. In the case of phosphorescent devices, the host material primarily confines excitons generated by the dopant within the light-emitting layer.

[0095] The charge transporting thin film of the present invention can be used as a functional layer provided between an anode and a light emitting layer in an organic EL device or a quantum dot EL device, and is suitable as a hole injection layer, a hole transport layer, or a hole injection transport layer.

[0096] When an EL device is produced using the charge transporting varnish of the present invention, the materials to be used and the production method thereof are as follows, but are not limited thereto.

[0097] An example of a method for producing an OLED device having a hole transport layer made of a thin film obtained from the charge transport varnish of the present invention is as follows. It is preferable to preliminarily perform surface treatment on the electrodes, such as washing with alcohol, pure water, or the like, or UV ozone treatment, oxygen plasma treatment, or the like, to the extent that this does not adversely affect the electrodes. A hole injection layer and a hole transport layer made of the charge transport thin film of the present invention are formed on an anode substrate by the above-described method. This substrate is then introduced into a vacuum deposition apparatus, and a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode metal are sequentially deposited by deposition. Alternatively, instead of forming the light-emitting layer by deposition in this method, these layers are formed by a wet process using a light-emitting layer-forming composition containing a light-emitting polymer. If necessary, an electron blocking layer may be provided between the light-emitting layer and the hole transport layer.

[0098] Examples of anode materials include transparent electrodes such as indium tin oxide (ITO) and indium zinc oxide (IZO), and metal anodes made of metals such as aluminum or alloys thereof, preferably those that have undergone planarization. Polythiophene derivatives and polyaniline derivatives with high charge transport properties can also be used. Other metals that can be used to make metal anodes include, but are not limited to, gold, silver, copper, indium, and alloys thereof.

[0099] Examples of materials for forming the hole injection layer include copper phthalocyanine, titanium oxide phthalocyanine, platinum phthalocyanine, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile, N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine, 2,7-bis[N,N-bis(4-methoxy-phenyl)amino]-9,9-spirobifluorene, 2,2'-bis[N,N-bis(4-methoxy-phenyl)amino]-9,9-spirobifluorene, N,N'-diphenyl-N,N'-di[4-(N,N-ditolylamino)phenyl]benzidine, N,N'-diphenyl-N,N'-di[4-(N,N-diphenylamino)phenyl]benzidine, N 4 , N 4' -(biphenyl-4,4'-diyl)bis(N 4 , N 4' , N 4' -triphenylbiphenyl-4,4'-diamine)N 1 , N 1' -(biphenyl-4,4'-diyl)bis(N 1 -phenyl-N 4 , N 4'-di-m-tolylbenzene-1,4-diamine), WO 2004 / 043117, WO 2004 / 105446, WO 2005 / 000832, WO 2005 / 043962, WO 2005 / 042621, WO 2005 / 107335, WO 2006 / 006459, WO 2006 / 025342, WO 2006 / 137473, WO 2007 / 049631, WO 2007 / 099808, WO 2008 / 010474, WO 2008 / 032 617, WO 2008 / 032616, WO 2008 / 129947, WO 2009 / 096352, WO 2010 / 041701, WO 2010 / 058777, WO 2010 / 058776, WO 2013 / 042623, WO 2013 / 129249, WO 2014 / 115865, WO 2014 / 132917, WO 2014 / 141998 and WO 2014 / 132834, and the like. However, it is not limited to these.

[0100] Examples of materials for forming the light-emitting layer include, but are not limited to, low-molecular-weight light-emitting materials such as metal complexes (e.g., aluminum complexes of 8-hydroxyquinoline), metal complexes of 10-hydroxybenzo[h]quinoline, bisstyrylbenzene derivatives, bisstyrylarylene derivatives, metal complexes of (2-hydroxyphenyl)benzothiazole, and silole derivatives; and systems in which a light-emitting material and an electron transfer material are mixed with a polymer compound (e.g., poly(p-phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly(3-alkylthiophene), or polyvinylcarbazole. Furthermore, when the light-emitting layer is formed by vapor deposition, it may be co-deposited with a light-emitting dopant. Examples of light-emitting dopants include, but are not limited to, metal complexes (e.g., tris(2-phenylpyridine)iridium(III) (Ir(ppy)), naphthacene derivatives (e.g., rubrene), quinacridone derivatives, and fused polycyclic aromatic rings (e.g., perylene).

[0101] Examples of materials for forming the electron transport layer / hole blocking layer include, but are not limited to, oxydiazole derivatives, triazole derivatives, phenanthroline derivatives, phenylquinoxaline derivatives, benzimidazole derivatives, and pyrimidine derivatives.

[0102] Materials for forming the electron injection layer include, but are not limited to, metal oxides such as lithium oxide (LiO), magnesium oxide (MgO), and alumina (AlO), and metal fluorides such as lithium fluoride (LiF) and sodium fluoride (NaF). Cathode materials include, but are not limited to, aluminum, magnesium-silver alloys, and aluminum-lithium alloys. Materials for forming the electron blocking layer include, but are not limited to, tris(phenylpyrazole)iridium.

[0103] Examples of the light-emitting polymer include polyfluorene derivatives such as poly(9,9-dialkylfluorene) (PDAF), polyphenylenevinylene derivatives such as poly(2-methoxy-5-(2'-ethylhexoxy)-1,4-phenylenevinylene) (MEH-PPV), polythiophene derivatives such as poly(3-alkylthiophene) (PAT), and polyvinylcarbazole (PVCz).

[0104] The quantum dot material may include at least one semiconductor material selected from the group consisting of II-VI semiconductors, III-V semiconductors, I-III-VI semiconductors, IV semiconductors, and I-II-IV-VI semiconductors. Specific examples of the semiconductor material include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, and CdHgZnT. e, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe; GaN, GaP, GaAs, G aSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, Ga InNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb; SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnS Examples of suitable gallium arsenide include, but are not limited to, Cu ...

[0105] As described above, the charge-transporting varnish of the present invention is suitably used for forming functional layers such as a hole injection layer, a hole transport layer, and a hole injection transport layer that are provided between an anode and a light-emitting layer in an organic EL device or a quantum dot EL device. However, it can also be used for forming charge-transporting thin films in electronic devices such as organic photoelectric conversion devices, organic thin-film solar cells, organic perovskite photoelectric conversion devices, organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic optical inspectors, organic photoreceptors, organic field quenching devices, light-emitting electrochemical cells, quantum lasers, organic laser diodes, and organic plasmon light-emitting devices.

[0106] [8] Charge-transporting varnish for quantum dot EL devices The present invention also provides a charge-transporting varnish for quantum dot EL devices, which contains copper(I) halide or pseudocopper(I) halide, one amine selected from the group consisting of amines represented by the following formulas (1) to (3), and a solvent:

[0107]

[0108] In formula (1), R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L is an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between HN- and -OH. In formula (3), R 5 ~R 6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxy group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or has an oxygen atom between the carbon atoms.

[0109] In the charge-transporting varnish for quantum dot EL devices, specific examples of the copper(I) halide or pseudocopper(I) halide, the amines represented by formulas (1) to (3), and the solvent are the same as those exemplified in the description of the charge-transporting varnish.

[0110] Taking electrical properties into consideration, the content of the copper(I) halide or pseudocopper(I) halide is preferably 10 to 95 mass % of the solid content, more preferably 10 to 70 mass %, even more preferably 20 to 60 mass %, and still more preferably 30 to 50 mass %.

[0111] The content of the amine is usually, taking into consideration the solubility of the copper(I) halide or pseudocopper(I) halide, and is preferably 1 to 10 moles, more preferably 2 to 8 moles, and even more preferably 3 to 7 moles per mole of the copper(I) halide or pseudocopper(I) halide.

[0112] The viscosity of the charge-transporting varnish for quantum dot EL devices is determined appropriately depending on the thickness of the thin film to be produced and the solid content concentration, but is usually 1 to 50 mPa·s at 25° C. In the present invention, the solid content means components other than the solvent contained in the charge-transporting varnish, but amines, which will be described later, are not included in the solid content.

[0113] The solids concentration of the charge-transporting varnish for quantum dot EL devices is determined appropriately taking into consideration the viscosity and surface tension of the varnish, the thickness of the thin film to be produced, and the like, but is usually about 0.1 to 10.0 mass %, and in consideration of improving the coatability of the varnish, it is preferably about 0.5 to 8.0 mass %, and more preferably about 1.0 to 6.0 mass %.

[0114] The method for preparing the charge transporting varnish for quantum dot EL devices is not particularly limited, but examples thereof include a method in which copper(I) halide or pseudocopper(I) halide and an amine are dissolved in a solvent.

[0115] In particular, when preparing a charge-transporting varnish for quantum dot EL devices, from the viewpoint of obtaining a thin film with higher flatness with good reproducibility, it is desirable to dissolve copper(I) halide or pseudocopper(I) halide in an organic solvent and then filter the solution using a filter or the like on the order of submicrometers before use.

[0116] The charge-transporting varnish for quantum dot EL devices described above can be used to easily produce a charge-transporting thin film for quantum dot EL devices. In this case, the charge-transporting thin film can be formed by applying the charge-transporting varnish for quantum dot EL devices described above to a substrate and baking it. The method for applying the varnish is not particularly limited, and examples include dipping, spin coating, transfer printing, roll coating, brush coating, inkjet coating, spraying, and slit coating. It is preferable to adjust the viscosity and surface tension of the varnish depending on the application method.

[0117] Furthermore, the atmosphere in which the charge-transporting varnish for quantum dot EL devices is baked after application is not particularly limited, and a thin film with a uniform film surface and high charge transport properties can be obtained not only in an air atmosphere but also in an inert gas such as nitrogen or in a vacuum. However, depending on the type of dopant substance used, a thin film with charge transport properties can sometimes be reproducibly obtained by baking the varnish in an air atmosphere.

[0118] The baking temperature is appropriately determined within a range of about 100 to 260° C., taking into consideration the use of the resulting thin film, the degree of charge transport property to be imparted to the resulting thin film, the type and boiling point of the solvent, etc. For example, when the resulting thin film is used as a hole transport layer of a quantum dot EL device, the baking temperature is preferably about 140 to 250° C., and more preferably about 145 to 240° C. During baking, the temperature may be changed in two or more stages for the purpose of achieving more uniform film formation or promoting a reaction on the substrate, and heating may be performed using an appropriate device such as a hot plate or an oven.

[0119] The thickness of the charge transport thin film is not particularly limited, but is preferably 20 to 300 nm when 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 a quantum dot EL device. Methods for changing the film thickness include changing the solid concentration in the varnish or changing the amount of solution on the substrate during application.

[0120] The present invention will be described in more detail 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.

[0121] (1) Application of charge transport varnish: Spin coater MS-A100 manufactured by Mikasa Co., Ltd. (2) Fabrication of hole-only device element: Multifunctional deposition system C-E2L1G1-N manufactured by Choshu Sangyo Co., Ltd. (3) Measurement of electrical properties of hole-only device element: Multi-channel IVL measurement device manufactured by EHC Co., Ltd. (4) Measurement of fluorescence intensity: Hitachi High-Technologies Corporation, F-7000 Hitachi spectrofluorophotometer (5) Measurement of film absorbance: Shimadzu Corporation, UV-3600 Shimadzu ultraviolet-visible-near-infrared spectrophotometer

[0122] [1] Production of Silica Sol [Production Example 1] 96.7 g of ST-OS (manufactured by Nissan Chemical Industries, Ltd.), which is a water-dispersed silica sol, and triethylene glycol monobutyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.; the same applies hereinafter) were placed in a recovery flask, and the water contained in the ST-OS was solvent-substituted with triethylene glycol monobutyl ether using an evaporator. The resulting mixture was filtered through a PTFE filter having a pore size of 1.0 μm, yielding a silica sol dispersed in triethylene glycol monobutyl ether (solid content concentration: 16.7% by mass).

[0123] [2] Preparation of Charge-Transporting Varnish [Example 1-1] 0.14 g (0.74 mmol) of copper iodide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; the same applies hereinafter), 0.39 g (4.38 mmol) of 1-amino-2-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.; the same applies hereinafter), 0.024 g of triethylene glycol monobutyl ether, and 5.60 g of diethylene glycol monoisobutyl ether (manufactured by Junsei Chemical Co., Ltd.; the same applies hereinafter) were placed in a glass vial and stirred at room temperature for 30 minutes using a stirrer. Thereafter, 0.84 g of the silica sol obtained in Production Example 1 was added, and the mixture was stirred at room temperature for 30 minutes. The resulting mixture was filtered through a PP syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 4.0% by mass).

[0124] Example 1-2 A charge-transporting varnish (solid concentration 4.0% by mass) was obtained in the same manner as in Example 1-1, except that 0.11 g (0.58 mmol) of copper iodide, 0.32 g (3.59 mmol) of 1-amino-2-butanol, 0.12 g of triethylene glycol monobutyl ether, 5.45 g of diethylene glycol monoisobutyl ether, and 1.00 g of silica sol were used.

[0125] Example 1-3 A charge-transporting varnish (solid content concentration 4.0% by mass) was obtained in the same manner as in Example 1-1, except that 0.084 g (0.44 mmol) of copper iodide, 0.24 g (2.69 mmol) of 1-amino-2-butanol, 0.058 g of triethylene glycol monobutyl ether, 5.45 g of diethylene glycol monoisobutyl ether, and 1.18 g of silica sol were used.

[0126] Example 1-4 A charge-transporting varnish (solid content concentration 4.0% by mass) was obtained in the same manner as in Example 1-1, except that 0.056 g (0.29 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 0.062 g of triethylene glycol monobutyl ether, 5.38 g of diethylene glycol monoisobutyl ether, and 1.34 g of silica sol were used.

[0127] Example 1-5 0.16 g (0.84 mmol) of copper iodide, 0.11 g (1.23 mmol) of 1-amino-2-butanol, 1.12 g of propylene glycol (Kanto Chemical Co., Ltd.), 1.86 g of propylene carbonate (Tokyo Chemical Industry Co., Ltd.), and 0.75 g of dipropylene glycol monomethyl ether (Tokyo Chemical Industry Co., Ltd.) were placed in a glass vial and stirred for 30 minutes at room temperature using a stirrer. The resulting mixture was filtered through a PP syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 4.0% by mass).

[0128] Comparative Example 1-1 0.036 g of TFB (poly[(9,9-dictylfluorenyl-2,7-diyl)-co-(4,4′(N-(4-sec-butylphenyl)diphenylamine))]) (Sigma-Aldrich) and 2.96 g of xylene (Kanto Chemical Co., Inc.) were placed in a glass vial and stirred at room temperature for 30 minutes using a stirrer. The resulting mixture was filtered through a PTFE syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 1.2% by mass).

[0129] Comparative Example 1-2 0.03 g of PVK (poly(9-vinylcarbazole), manufactured by Sigma-Aldrich) and 2.97 g of chlorobenzene (manufactured by Kanto Chemical Co., Inc.) were placed in a glass vial and stirred at room temperature for 30 minutes using a stirrer. The resulting mixture was filtered through a PTFE syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 1.0% by mass).

[0130] [3] Fabrication and Evaluation of QD-Hole-Only Devices (HODs) [Example 2-1] The charge-transporting varnish prepared in Example 1-1 was applied to an ITO substrate using a spin coater, and the resulting coating was dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. The coating was then baked on a hot plate in an air atmosphere at 170°C for 15 minutes to form a uniform 40 nm charge-transporting thin film on the ITO substrate. The ITO substrate used was a 25 mm x 25 mm x 0.7 mm glass substrate with a patterned 50 nm thick ITO film formed on its surface. Prior to use, impurities on the surface were removed using an O2 plasma cleaning device (150 W, 30 seconds) (hereinafter the same). Next, a toluene dispersion of QDs (QNA-PB.dot.019, manufactured by QNA Corporation; the same applies hereinafter) concentrated to 2.7% by mass was applied to the ITO substrate with the thin film formed thereon using a spin coater under a N atmosphere, and then baked at 100°C for 10 minutes to form a 25 nm thin film (QD layer). Then, a vacuum deposition apparatus (vacuum degree 1.0 × 10 -5 The QD-HOD was fabricated by depositing aluminum at a deposition rate of 0.2 nm / sec to a thickness of 80 nm using a vacuum oven.

[0131] To prevent deterioration of characteristics due to the influence of oxygen, water, etc. in the air, the QD-HOD was sealed with a sealing substrate before its characteristics were evaluated. Sealing was performed as follows. In a nitrogen atmosphere with an oxygen concentration of 2 ppm or less and a dew point of -76°C or less, the QD-HOD was placed between sealing substrates, and the sealing substrates were bonded together with an adhesive (Moresco Moisture Cut WB90US(P) manufactured by MORESCO Corporation). At this time, a moisture scavenger (HD-071010W-40 manufactured by DYNIC Co., Ltd.) was placed inside the sealing substrate together with the QD-HOD. The bonded sealing substrates were irradiated with UV light (wavelength: 365 nm, irradiation dose: 6,000 mJ / cm). 2 ), and then annealed at 80°C for 1 hour to cure the adhesive.

[0132] Examples 2-2 to 2-5 QD-HODs were prepared in the same manner as in Example 2-1, except that the charge-transporting varnish was changed to the charge-transporting varnishes prepared in Examples 1-2 to 1-5, respectively.

[0133] [Comparative Example 2-1] PEDOT / PSS (Clevios P ​​VP.Al 4083, manufactured by Heraeus) was applied to an ITO substrate using a spin coater, and the resulting coating was baked on a hot plate in an air atmosphere at 120°C for 1 minute and then at 150°C for 30 minutes to form a uniform 40 nm charge-transporting thin film on the ITO substrate. Next, the charge-transporting varnish prepared in Comparative Example 1-1 was applied to the ITO substrate with the thin film formed using a spin coater and baked in an N2 atmosphere at 200°C for 30 minutes to form a uniform 40 nm charge-transporting thin film. Next, a QD thin film was formed and aluminum was vapor-deposited in the same manner as in Example 2-1 above to produce a QD-HOD.

[0134] [4] Fabrication and Evaluation of Vapor-Deposited Hole-Only Device (HOD) [Example 3-1] The charge-transporting varnish prepared in Example 1-1 was applied to an ITO substrate using a spin coater, and the resulting coating was dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. It was then baked on a hot plate in an air atmosphere at 170°C for 15 minutes to form a uniform 40 nm charge-transporting thin film on the ITO substrate. Next, the emitting layer host material NS60 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) and the emitting layer dopant material Ir(ppy)3 were co-deposited. The deposition rate was controlled so that the Ir(ppy)3 concentration was 6%, and a 40 nm layer was deposited. Next, thin films of Alq3, lithium fluoride, and aluminum were sequentially deposited to obtain a vapor-deposited HOD. In this case, the deposition rate was 0.2 nm / sec for Alq3 and aluminum, and 0.02 nm / sec for lithium fluoride, and the film thicknesses were 20 nm, 0.5 nm, and 80 nm, respectively.

[0135] Example 3-2 A deposition-HOD was prepared in the same manner as in Example 3-1, except that the thickness of the charge transporting thin film was changed to 80 nm.

[0136] Examples 3-3 to 3-5 Vapor deposition-HODs were prepared in the same manner as in Example 3-1, except that the charge transporting varnish was changed to the charge transporting varnishes prepared in Examples 1-2, 1-3 and 1-5, respectively.

[0137] Comparative Example 3-1: PEDOT / PSS (Clevios P ​​VP.Al 4083, manufactured by Heraeus) was applied to an ITO substrate using a spin coater, and the resulting coating was baked on a hot plate in an air atmosphere at 120°C for 1 minute and then at 150°C for 30 minutes to form a uniform 40 nm charge-transporting thin film on the ITO substrate. Next, the charge-transporting varnish prepared in Comparative Example 1-1 was applied to the ITO substrate with the thin film formed thereon using a spin coater and baked in an N2 atmosphere at 200°C for 30 minutes to form a uniform 40 nm charge-transporting thin film. Next, co-evaporation of NS60 and Ir(ppy)3, and deposition of thin films of Alq3, lithium fluoride, and aluminum were performed in the same manner as in Example 3-1 above to prepare a vapor-deposition-HOD.

[0138] The current-voltage characteristics were evaluated for the devices fabricated in Examples 2-1 to 2-5 and Comparative Example 2-1, and Examples 3-1 to 3-5 and Comparative Example 3-1. Specifically, the current density (mA / cm) was measured when a voltage was applied to the fabricated deposition-HOD from −5 V to +5 V in 0.25 V increments. 2 The results of measuring the current density when a voltage of +5 V was applied to each of the above elements are shown in Tables 1 and 2.

[0139]

[0140]

[0141] As shown in Table 1, when a voltage of +5 V was applied to the QD-HODs of Examples 2-1 to 2-5, the current density was higher than that of the QD-HOD prepared in Comparative Example 2-1. Similarly, as shown in Table 2, the current density obtained by vapor deposition-HOD in Examples 3-1 to 3-5 was higher than that obtained by vapor deposition-HOD in Comparative Example 3-1. From these results, it can be said that charge-transporting thin films using copper iodide have excellent conductivity.

[0142] [5] Preparation and Evaluation of Photoluminescence (PL) Evaluation Substrates [Example 4-1] The charge-transporting varnish prepared in Example 1-1 was applied to a quartz substrate using a spin coater. The resulting coating was then dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. The resulting coating was then baked on a hot plate in an air atmosphere at 170°C for 15 minutes to form a uniform 40 nm charge-transporting thin film on the quartz substrate. The quartz substrates used had been previously cleaned of surface impurities using an O2 plasma cleaning device (150 W, 30 seconds). Next, a toluene dispersion of QDs concentrated to 2.7% by mass was applied to the thin-film-formed quartz substrate using a spin coater under a N2 atmosphere. The substrate was then baked at 100°C for 10 minutes to form a 30 nm thin film (QD layer), thereby preparing a PL evaluation substrate. To prevent performance degradation due to the effects of oxygen and water in the air, the PL evaluation substrates were sealed with a sealing substrate before their performance evaluation. Sealing was performed as follows: In a nitrogen atmosphere with an oxygen concentration of 2 ppm or less and a dew point of −76° C. or less, the PL evaluation substrate was placed between sealing substrates, and the sealing substrates were bonded together with an adhesive (Moresco Moisture Cut WB90US(P), manufactured by MORESCO Corporation).

[0143] Example 4-2 A PL evaluation substrate was produced in the same manner as in Example 4-1, except that the charge transporting varnish was changed to the charge transporting varnish prepared in Example 1-5.

[0144] Comparative Example 4-1 A PL evaluation substrate was produced in the same manner as in Example 4-1, except that no charge transporting thin film was formed and only a QD layer was formed.

[0145] Table 3 shows the detailed configuration of the PL evaluation board fabricated above.

[0146]

[0147] The fluorescence intensity of the QD layer in the PL evaluation substrates prepared in Examples 4-1 and 4-2 and Comparative Example 4-1 was measured. Specifically, excitation light of 365 nm was irradiated from the sealing substrate side, and the fluorescence spectrum from 385 nm to 600 nm was obtained. The obtained fluorescence spectrum is shown in Figure 1.

[0148] The results in Figure 1 show that the fluorescence intensity of the QDs in the substrate of Example 4-2, which does not contain SiO nanoparticles, is significantly lower than that of Comparative Example 4-1 (QD layer only). On the other hand, Example 4-1, which contains SiO nanoparticles, has a stronger fluorescence spectrum intensity than Example 4-2, suggesting that the inclusion of SiO nanoparticles can suppress PL quenching.

[0149] [6] Solvent Resistance Test [Example 5-1] The charge-transporting varnish prepared in Example 1-2 was applied to a quartz substrate using a spin coater, and the resulting coating was dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. The resulting coating was then baked on a hot plate in an air atmosphere at 170°C for 15 minutes to form a uniform 40 nm charge-transporting thin film on the quartz substrate. Two such substrates were prepared, and 1 g of toluene was applied to one of the substrates. The substrate was then left to stand for 15 minutes, after which the toluene was removed with an air blower. Both the toluene-treated and untreated substrates were baked in an N2 atmosphere at 230°C for 5 minutes. The quartz substrates used had surface impurities removed using an O2 plasma cleaning device (150 W, 30 seconds) before use. The film absorbance of both the toluene-treated and untreated substrates was measured, and the remaining film ratio was calculated from the film absorbance values ​​at the respective peak tops using the following formula: Film remaining rate = [film absorbance of substrate after toluene treatment] / [film absorbance of untreated substrate] × 100 [%]

[0150] Example 5-2 A solvent resistance test was carried out in the same manner as in Example 5-1, except that the charge-transporting varnish was changed to the charge-transporting varnish prepared in Example 1-5.

[0151] Comparative Examples 5-1 and 5-2 Solvent resistance tests were carried out in the same manner as in Example 5-1, except that the charge transporting varnishes were changed to the charge transporting varnishes prepared in Comparative Examples 1-1 and 1-2, respectively.

[0152] The film absorbances measured in Examples 5-1 and 5-2 and Comparative Examples 5-1 and 5-2 are shown in FIGS. 2 to 5, and the film remaining rates calculated from the film absorbances are shown in Table 4.

[0153]

[0154] 2 to 5, thin films containing PVK or TFB, which are commonly used as hole transport materials, such as those in Comparative Examples 5-1 and 5-2, have extremely low solvent resistance to toluene. On the other hand, thin films containing copper iodide, such as those in Examples 5-1 and 5-2, have excellent solvent resistance to toluene.

[0155] [7] Production of Silica Sol [Production Example 2] 39.2 g of ST-OS (manufactured by Nissan Chemical Industries, Ltd.), which is a water-dispersed silica sol, and 42.0 g of dipropylene glycol monomethyl ether (manufactured by Kanto Chemical Co., Ltd.; the same applies hereinafter) were placed in a recovery flask, and the water contained in the ST-OS was solvent-substituted with dipropylene glycol monomethyl ether using an evaporator. Thereafter, the mixture was filtered through a PTFE filter having a pore size of 1.0 μm, to obtain a silica sol dispersed in dipropylene glycol monomethyl ether (solids concentration: 16.0% by mass).

[0156] [8] Preparation of Charge-Transporting Varnish [Example 6-1] 0.11 g (0.58 mmol) of copper iodide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; the same applies hereinafter), 0.16 g (1.79 mmol) of 1-amino-2-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.; the same applies hereinafter), 3.28 g of diethylene glycol (manufactured by Kanto Chemical Co., Ltd.; the same applies hereinafter), and 2.40 g of dipropylene glycol monomethyl ether were placed in a glass vial and stirred at room temperature for 30 minutes using a stirrer. Then, 1.05 g of the silica sol obtained in Production Example 2 was added, and the mixture was stirred at room temperature for 30 minutes. The resulting mixture was filtered through a PP syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 4.0% by mass).

[0157] Example 6-2: 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.61 g of diethylene glycol, and 3.03 g of dipropylene glycol monomethyl ether were stirred in the same manner as in Example 6-1, and then 0.047 g (0.23 mmol) of pentafluorobenzenethiol (Tokyo Chemical Industry Co., Ltd.; the same applies hereinafter) was added and stirred at room temperature for 30 minutes. 1.05 g of the silica sol obtained in Production Example 2 was then added and stirred at room temperature for 30 minutes. The resulting mixture was filtered through a PP syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 4.0% by mass).

[0158] Example 6-3 A charge-transporting varnish (solid content concentration 4.0% by mass) was obtained in the same manner as in Example 6-2, except that 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.60 g of diethylene glycol, 3.01 g of dipropylene glycol monomethyl ether, 0.071 g (0.35 mmol) of pentafluorobenzenethiol, and 1.05 g of silica sol were used.

[0159] Example 6-4 A charge-transporting varnish (solid content concentration 4.0% by mass) was obtained in the same manner as in Example 6-2, except that 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.60 g of diethylene glycol, 2.99 g of dipropylene glycol monomethyl ether, 0.12 g (0.60 mmol) of pentafluorobenzenethiol, and 1.05 g of silica sol were used.

[0160] Example 6-5 A charge-transporting varnish (solid content concentration 4.0% by mass) was obtained in the same manner as in Example 6-2, except that 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.55 g of diethylene glycol, 2.95 g of dipropylene glycol monomethyl ether, 0.18 g (0.90 mmol) of pentafluorobenzenethiol, and 1.05 g of silica sol were used.

[0161] Example 6-6 A charge-transporting varnish (solid concentration 4.0% by mass) was obtained in the same manner as in Example 6-2, except that 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.60 g of diethylene glycol, 3.02 g of dipropylene glycol monomethyl ether, 0.065 g (0.36 mmol) of pentafluoroaniline (manufactured by Tokyo Chemical Industry Co., Ltd.; the same applies hereinafter) instead of pentafluorobenzenethiol, and 1.05 g of silica sol.

[0162] Example 6-7 A charge-transporting varnish (solid concentration 4.0% by mass) was obtained in the same manner as in Example 6-2, except that 0.11 g (0.58 mmol) of copper iodide, 0.16 g (1.79 mmol) of 1-amino-2-butanol, 2.60 g of diethylene glycol, 2.96 g of dipropylene glycol monomethyl ether, 0.16 g (0.87 mmol) of pentafluoroaniline, and 1.05 g of silica sol were used.

[0163] [Examples 6-8] 0.089 g (0.47 mmol) of copper iodide, 0.023 g (0.19 mmol) of copper thiocyanate (FUJIFILM Wako Pure Chemical Industries, Ltd.), 0.45 g (5.05 mmol) of 1-amino-2-butanol, 2.45 g of diethylene glycol, and 2.80 g of dipropylene glycol monomethyl ether were placed in a glass vial and stirred at room temperature for 30 minutes. Then, 0.014 g (0.07 mmol) of pentafluorobenzenethiol was added and stirred at room temperature for 30 minutes. Then, 1.05 g of the silica sol obtained in Production Example 2 was added and stirred at room temperature for 30 minutes. The resulting mixture was filtered through a PP syringe filter with a pore size of 0.2 μm to obtain a charge-transporting varnish (solids concentration: 4.0% by mass).

[0164] [9] Fabrication and Evaluation of Hole-Only Device (HOD) [Example 7-1] The charge-transporting varnish prepared in Example 6-1 was applied to an ITO substrate using a spin coater, and the resulting coating was dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. The coating was then baked on a hot plate in an air atmosphere at 230°C for 30 minutes to form a uniform 60 nm charge-transporting thin film on the ITO substrate. The ITO substrate used was a 25 mm x 25 mm x 0.7 mm glass substrate with a patterned 50 nm thick ITO film formed on its surface. Prior to use, impurities on the surface were removed using an O2 plasma cleaning device (150 W, 30 seconds) (hereinafter the same). Next, the ITO substrate with the thin film formed thereon was vacuum-evaporated using a vacuum deposition device (vacuum 1.0 x 10 -5 NPB was evaporated at a deposition rate of 2.0 nm / sec to a thickness of 60 nm using a vacuum oven. Next, aluminum was evaporated at a deposition rate of 0.2 nm / sec to a thickness of 80 nm to form a cathode, thereby producing an HOD.

[0165] To prevent deterioration of characteristics due to the influence of oxygen, water, etc. in the air, the HOD was sealed with a sealing substrate before its characteristics were evaluated. Sealing was performed as follows. In a nitrogen atmosphere with an oxygen concentration of 2 ppm or less and a dew point of -76°C or less, the QD-HOD was placed between sealing substrates, and the sealing substrates were bonded together with an adhesive (Moresco Moisture Cut WB90US(P), manufactured by MORESCO Corporation). At this time, a moisture scavenger (HD-071010W-40, manufactured by DYNIC Co., Ltd.) was placed inside the sealing substrate together with the QD-HOD. The bonded sealing substrates were irradiated with UV light (wavelength: 365 nm, irradiation dose: 6,000 mJ / cm). 2 ) and then annealed at 80°C for 1 hour to harden the adhesive.

[0166] Examples 7-2 to 7-7 HODs were prepared in the same manner as in Example 7-1, except that the charge-transporting varnish was changed to the charge-transporting varnishes prepared in Examples 6-1 to 6-7, respectively.

[0167] [Examples 7-8] The charge-transporting varnish prepared in Examples 6-5 was applied to an ITO substrate using a spin coater, and the resulting coating was dried under reduced pressure (vacuum) of 10 Pa or less for 15 minutes. The coating was then baked on a hot plate in an air atmosphere at 230°C for 30 minutes to form a uniform 60 nm charge-transporting thin film on the ITO substrate. Next, a xylene solution (solids concentration 2.0% by mass) of the prepared TFB (poly[(9,9-dictylfluorenyl-2,7-diyl)-co-(4,4'(N-(4-sec-butylphenyl)diphenylamine))]) (Sigma-Aldrich) was applied to the ITO substrate with the thin film formed thereon using a spin coater, and the resulting coating was dried at 200°C for 30 minutes to form a uniform 60 nm charge-transporting thin film. Next, aluminum was evaporated at a deposition rate of 0.2 nm / sec to a film thickness of 80 nm to form a cathode, thereby producing an HOD.

[0168] Examples 7-9 HOD was prepared in the same manner as in Examples 7-8, except that the charge-transporting varnish was changed to the charge-transporting varnish prepared in Examples 6-8.

[0169] The current-voltage characteristics of the devices fabricated in Examples 7-1 to 7-7, 7-8, and 7-9 were evaluated. Specifically, the current density (mA / cm) was measured when a voltage was applied to the fabricated deposition-HOD from −5 V to +5 V in 0.25 V increments. 2 The measurement results when a voltage of +5 V was applied to each of the above elements are shown in Tables 5 and 6.

[0170]

[0171]

[0172] As shown in Table 5, the current density when a voltage of +5 V was applied to the HODs of Examples 7-2 to 7-7 was higher than that of the HOD prepared in Example 7-1. Similarly, as shown in Table 6, the current density obtained with the HOD of Example 7-9 was higher than that of the HOD of Example 7-8. These results indicate that the addition of pentafluorobenzenethiol or pentafluoroaniline further improves the conductivity of charge-transporting thin films using copper iodide.

Claims

1. A charge-transporting varnish comprising copper halide (I) or pseudocopper halide (I), one selected from the group consisting of amines represented by the following formulas (1) to (3), SiO2 nanoparticles, and a solvent. (In formula (1), R 1 ~R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L represents an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between H2N- and -OH. In formula (3), R 5 ~R 6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or has an oxygen atom between the carbon atoms.

2. The charge transporting varnish according to claim 1, wherein the content of said amine is 1 to 40 moles per mole of copper(I) halide or pseudocopper(I) halide.

3. The charge-transporting varnish according to claim 1, wherein the content of said copper(I) halide or pseudocopper(I) halide is 10 to 95% by mass based on the solid content.

4. The charge-transporting varnish according to claim 1, wherein the content of the SiO2 nanoparticles is 5 to 90% by mass of the solid content.

5. The charge transporting varnish according to claim 1, wherein said copper(I) halide or pseudocopper(I) halide is copper(I) halide or copper(I) thiocyanate.

6. The charge transporting varnish according to claim 5, wherein said copper(I) halide is copper(I) iodide.

7. The charge transporting varnish according to claim 1, wherein said amine is any one of the amines represented by the following formulas:

8. The charge transporting varnish according to claim 1, further comprising a compound represented by the following formula (X): (In the formula, A represents an aromatic hydrocarbon ring or an aromatic heterocycle having a carbon atom constituting the ring; R x are groups bonded to carbon atoms constituting the ring, and each independently represents a hydroxy group, a silanol group, a thiol group, an amino group, a carboxy group, a phosphoric acid group, a phosphoric acid ester group, an ester group, a thioester group, an amide group, a sulfonamide group, a nitro group, a substituted or unsubstituted monovalent hydrocarbon group, an organooxy group, an organoamino group, an organosilyl group, an organothio group, an acyl group, a sulfo group, a cyano group, a chlorine atom, a bromine atom, or an iodine atom; a represents an integer satisfying 6≦a when A is an aromatic hydrocarbon ring, and an integer satisfying 1≦a when A is an aromatic heterocycle; m represents an integer satisfying 1≦m≦a; n represents an integer satisfying 0≦n≦a-1; p represents an integer satisfying 0≦p≦a-1, and m+n+p≦a is satisfied.

9. The charge transporting varnish according to claim 8, wherein A is an aromatic hydrocarbon ring.

10. The charge transporting varnish according to claim 9, wherein A is a benzene ring.

11. The above R x The charge transporting varnish according to claim 8, wherein each of the groups independently represents a thiol group, an amino group or an organothio group.

12. The charge transporting varnish according to claim 8, wherein the content of the compound represented by formula (X) is 0.1 to 2.0 moles per mole of the copper(I) halide or pseudocopper(I) halide.

13. A charge-transporting thin film obtained from the charge-transporting varnish according to any one of claims 1 to 12.

14. An electronic device comprising the charge transporting thin film according to claim 13.

15. The electronic device according to claim 14, wherein said charge transporting thin film is a hole injection layer, a hole transport layer or a hole injection transport layer.

16. The electronic device according to claim 15, which is an organic EL device or a quantum dot EL device.

17. A charge transporting varnish for a quantum dot EL device, comprising copper (I) halide or pseudocopper (I) halide, one member selected from the group consisting of amines represented by the following formulas (1) to (3), and a solvent: (In formula (1), R 1 ~R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In formula (2), L represents an alkylene group having 3 to 8 carbon atoms, and the alkylene group may have an oxygen atom between the carbon atoms. However, there are at least three carbon atoms between H2N- and -OH. In formula (3), R 5 ~R 6 each independently represents an alkyl group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, and the alkyl group may have an oxygen atom between the carbon atoms. 5 and R 6 At least one of the alkyl groups is substituted with a hydroxy group or has an oxygen atom between the carbon atoms.