JP2020178100A - Light-emitting device - Google Patents

Abstract

To provide a light-emitting device having an excellent device life.SOLUTION: The light-emitting device includes an anode, a light-emitting layer, an electron transport layer, and a cathode arranged in this order. The electron transport layer includes non-conductive particles, an electron transport polymer material having a structural unit represented by a formula (ET-1), and a non-particulate alkali metal compound represented by a formula (hh-1). (M3)a5(Z3)b1(hh-1)SELECTED DRAWING: None

Description

The present invention relates to a light emitting device.

In recent years, research on light emitting elements such as organic EL elements using thin films of organic substances has been actively conducted for applications such as lighting devices and display devices. As a light emitting element having improved brightness, for example, a light emitting element using a composition containing a polymer compound and an ionic compound in the electron transport layer described in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 2012-214689

However, the light emitting device described in Patent Document 1 does not have a sufficient device life.
Therefore, an object of the present invention is to provide a light emitting device having an excellent device life.

The present invention provides the following [1] to [11].
[1] A light emitting element in which an anode, a light emitting layer, an electron transport layer, and a cathode are arranged in this order, and the electron transport layer is composed of non-conductive particles and a structure represented by the formula (ET-1). A light emitting element containing an electron-transporting polymer material having a unit and a non-particulate alkali metal compound represented by the formula (hh-1).
[In equation (ET-1), nE1 represents an integer of 1 or more.
Ar ^E1 represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
^RE1 may have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, and a substituent. Represents an alkoxy group, a cycloalkoxy group which may have a substituent, an aryloxy group which may have a substituent, or a monovalent group containing a hetero atom which may have a substituent. .. When there are a plurality of ^RE1 , they may be the same or different. ]
(M ³ ) _a5 (Z ³ ) _b1 (hh-1)
[In formula (hh-1), M ³ represents an alkali metal cation. If M ³ is plurally present, they may be the same or different.
Z ^{3 is, F -, Cl -, Br} -, I -, OH -, B (R p) 4 -, R p SO 3 -, R p COO -, R p O -, ClO -, ClO 2 -, _{^{ClO 3 -, ClO 4 -,}} SCN -, CN -, NO 3 -, CO 3 2-, SO 4 2-, HSO 4 -, PO 4 3-, HPO 4 2-, H 2 PO 4 -, BF 4 ^- or PF ₆ ^- is. R ^p is a monovalent organic group having 1 to 15 carbon atoms. When a plurality of R ^ps exist, they may be the same or different.
a5 and b1 are each independently an integer of 1 or more. However, a5 and b1 are selected so that the charge of the alkali metal compound represented by the formula (hh-1) becomes 0. ]
[2] The light emitting device according to [1], wherein the Z average particle diameter of the non-conductive particles is larger than 100 nm and 300 nm or less.
[3] The light emitting device according to [1] or [2], wherein the non-conductive particles contain at least one of silica particles and polystyrene particles.
[4] The light emitting device according to any one of [1] to [3], wherein the ratio of the non-conductive particles is 1 to 200 parts by mass with respect to 100 parts by mass of the electron-transporting polymer material.
[5] One of [1] to [4], wherein the ratio of the non-particle-like alkali metal compound is 0.1 to 150 parts by mass with respect to 100 parts by mass of the electron-transporting polymer material. The light emitting element described.
[6] The light emitting device according to any one of [1] to [5], wherein the number of the non-conductive particles per unit area in the electron transport layer is 0.2 particles / μm ² or more.
[7] The method according to any one of [1] to [6], wherein the cathode and the electron transport layer are in contact with each other, and the root mean square roughness of the interface between the cathode and the electron transport layer is 5 nm or more. Light emitting element.
[8] The light emitting device according to any one of [1] to [7], wherein the electron-transporting polymer material contains a metal cation.
[9] The light emitting device according to [8], wherein the metal cation is a cation of M ^{3 in} the formula (hh-1).
[10] The line profile of the energy dispersive X-ray spectroscopy of the transmission electron microscope for the alkali metal element in the electron transport layer shows a peak, and the half-value full width of the peak is 18 nm or more and 55 nm or less [1]. The light emitting element according to any one of [9].

[11] A method for manufacturing a light emitting element in which an anode, a light emitting layer, an electron transporting layer and a cathode are arranged in this order, wherein the electron transporting layer is represented by a non-conductive particle and the formula (ET-1). An electron-transporting polymer material having a structural unit to be formed, and a non-particulate alkali metal compound represented by the formula (hh-1).
The non-conductive particles, the electron-transporting polymer material having a structural unit represented by the formula (ET-1), and the non-particle-like alkali metal compound represented by the formula (hh-1). A method for producing a light emitting element, which comprises a step of applying a composition containing and to form the electron transport layer.
[In equation (ET-1), nE1 represents an integer of 1 or more.
Ar ^E1 represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
^RE1 may have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, and a substituent. Represents an alkoxy group, a cycloalkoxy group which may have a substituent, an aryloxy group which may have a substituent, or a monovalent group containing a hetero atom which may have a substituent. .. When there are a plurality of ^RE1 , they may be the same or different. ]
(M ³ ) _a5 (Z ³ ) _b1 (hh-1)
[In formula (hh-1), M ³ represents an alkali metal cation. If M ³ is plurally present, they may be the same or different.
Z ^{3 is, F -, Cl -, Br} -, I -, OH -, B (R p) 4 -, R p SO 3 -, R p COO -, R p O -, ClO -, ClO 2 -, _{^{ClO 3 -, ClO 4 -,}} SCN -, CN -, NO 3 -, CO 3 2-, SO 4 2-, HSO 4 -, PO 4 3-, HPO 4 2-, H 2 PO 4 -, BF 4 ^- or PF ₆ ^- is. R ^p is a monovalent organic group having 1 to 15 carbon atoms. When a plurality of R ^ps exist, they may be the same or different.
a5 and b1 are each independently an integer of 1 or more. However, a5 and b1 are selected so that the charge of the alkali metal compound represented by the formula (hh-1) becomes 0. ]

The light emitting device according to the present invention has an excellent device life.

It is a schematic sectional view of the light emitting element in one aspect of this invention. It is a photograph of the electron transport layer obtained in Example 1 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 2 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 3 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 4 by the atomic force microscope image of the film formed on the glass substrate. It is a photograph of the electron transport layer obtained in Example 5 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph by the atomic force microscope image of the film which formed the electron transport layer obtained in Example 6 on a glass substrate. It is a photograph of the electron transport layer obtained in Example 7 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 8 formed on a glass substrate by an atomic force microscope image. It is a photograph of the electron transport layer obtained in Example 9 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 10 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Example 11 by an atomic force microscope image of a film formed on a glass substrate. It is a photograph of the electron transport layer obtained in Comparative Example 1 by an atomic force microscope image of a film formed on a glass substrate.

Hereinafter, one embodiment of the present invention will be described in detail.

<Explanation of common terms>
Unless otherwise specified, the terms commonly used in the present specification have the following meanings.

Me represents a methyl group, Et represents an ethyl group, Bu represents a butyl group, i-Pr represents an isopropyl group, t-Bu represents a tert-butyl group, and Ph represents a phenyl group.

The hydrogen atom may be a deuterium atom or a light hydrogen atom.

In the formula representing the metal complex, the solid line representing the bond between the ligand and the central metal means a covalent bond or a coordination bond.

The “polymer compound” means a polymer having a molecular weight distribution and having a polystyrene-equivalent number average molecular weight of 1 × 10 ³ or more (for example, 1 × 10 ³ to 1 × 10 ⁸ ). The polymer compound may be any of a block copolymer, a random copolymer, an alternating copolymer, and a graft copolymer, and may be in other embodiments.

If the polymerization active group remains as it is in the terminal group of the polymer compound, the light emission characteristic or the luminance life may be deteriorated when the polymer compound is used for manufacturing a light emitting element. Therefore, the terminal group of the polymer compound is preferably a stable group. The terminal group is preferably a group conjugated to the main chain, and examples thereof include a group bonded to an aryl group or a monovalent heterocyclic group via a carbon-carbon bond.

The “constituent unit” means a unit existing in one or more in a polymer compound. Generally, a unit existing in two or more in a polymer compound is called a "repeating unit".

By "low molecular compound" does not have a molecular weight distribution, molecular weight means a 1 × 10 ⁴ or less of the compound.

The "alkyl group" may be either linear or branched. The number of carbon atoms of the linear alkyl group is usually 1 to 50, preferably 1 to 10, and more preferably 1 to 6. The number of carbon atoms of the branched alkyl group is usually 3 to 50, preferably 3 to 30, and more preferably 4 to 20.

Examples of such alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, 2-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isoamyl group and 2-. Ethylbutyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, 3-propylheptyl group, n-decyl group, 3,7-dimethyloctyl group, 2-ethyloctyl group, 2- Examples thereof include a hexyl decyl group and an n-dodecyl group.

When the "alkyl group" has a substituent, specifically, a part or all of the hydrogen atoms in these groups (for example, one to all the hydrogen atoms that can be substituted) are a cycloalkyl group, an alkoxy group, and the like. Examples thereof include a cycloalkoxy group, an aryl group, a group substituted with a fluorine atom and the like.

Examples of such an "alkyl group having a substituent" include a trifluoromethyl group, a pentafluoroethyl group, a perfluorobutyl group, a perfluorohexyl group, a perfluorooctyl group, a 3-phenylpropyl group, and 3-( Examples include 4-methylphenyl) propyl group, 3- (3,5-di-hexylphenyl) propyl group, and 6-ethyloxyhexyl group. When the alkyl group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9, 1 to 5, or 1 to 1. Three and the like can be mentioned.

Examples of the "alkylene group" include a divalent group obtained by removing one hydrogen atom from the above-mentioned "alkyl group".

The number of carbon atoms of the "cycloalkyl group" is usually 3 to 50, preferably 3 to 30, and more preferably 4 to 20.

Examples of the "cycloalkyl group" include a cyclopropyl group, a cyclobutyl group and a cyclohexyl group.

"Aryl group" means the remaining atomic group excluding one hydrogen atom directly bonded to a carbon atom forming a ring from an aromatic hydrocarbon. The number of carbon atoms of the aryl group is usually 6 to 60, preferably 6 to 20, and more preferably 6 to 10.

The "aryl group" may have a substituent.
Examples of the "aryl group which may have a substituent" include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthrasenyl group, a 2-anthrasenyl group, a 9-anthrasenyl group and a 1-pyrenyl group. , 2-Pyrenyl group, 4-Pyrenyl group, 2-Fluolenyl group, 3-Fluolenyl group, 4-Phenyl group, 2-Phenylphenyl group, 3-Phenylphenyl group, 4-Phenylphenyl group and the like. Aryl groups are such that some or all of the hydrogen atoms in these groups (eg, 1 to all substitutable hydrogen atoms) are alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkoxy groups, aryl groups, or fluorine. It may be a group substituted with an atom or the like. When the aryl group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9, 1 to 5, or 1 to 1. Three and the like can be mentioned.

The "alkoxy group" may be either linear or branched. The number of carbon atoms of the linear alkoxy group is usually 1 to 40, preferably 1 to 6. The number of carbon atoms of the branched alkoxy group is usually 3 to 40, preferably 4 to 10.

Examples of the "alkoxy group" include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a tert-butyloxy group, an n-pentyloxy group and an n-hexyloxy group. , N-Heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, n-nonyloxy group, n-decyloxy group, 3,7-dimethyloctyloxy group, lauryloxy group and the like.

The "alkoxy group" may have a substituent.
As the "alkoxy group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are a cycloalkyl group, an alkoxy group, a cycloalkoxy group, or an aryl. Examples thereof include a group or a group substituted with a fluorine atom or the like. When the alkoxy group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9, 1 to 5, or 1 to 1. Three and the like can be mentioned.

The number of carbon atoms of the "cycloalkoxy group" is usually 3 to 40, preferably 4 to 10.

The cycloalkoxy group may have a substituent. Examples of the cycloalkoxy group include a cyclohexyloxy group.

The "aryloxy group" usually has 6 to 60 carbon atoms, preferably 6 to 48 carbon atoms.

Examples of the aryloxy group include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 1-anthrasenyloxy group, a 9-anthrasenyloxy group, a 1-pyrenyloxy group and the like.

The aryloxy group may have a substituent.
As the "aryloxy group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are an alkyl group, a cycloalkyl group, an alkoxy group, or a cyclo. Examples thereof include an alkoxy group or a group substituted with a fluorine atom or the like. When the aryloxy group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted. Specifically, 1 to 9, 1 to 5, or 1 ~ 3 etc. can be mentioned.

The "alkylsulfenyl group" may be either linear or branched. The number of carbon atoms of the linear alkylsulfenyl group is usually 1 to 40, preferably 4 to 10. The number of carbon atoms of the branched alkylsulphenyl group is usually 3 to 40, preferably 4 to 10.

Examples of the "alkylsulphenyl group" include methylsulphenyl group, ethylsulphenyl group, propylsulphenyl group, isopropylsulphenyl group, butylsulphenyl group, isobutylsulphenyl group, tert-butylsulphenyl group and pentylsul. Phenyl group, hexylsulphenyl group, heptylsulphenyl group, octylsulphenyl group, 2-ethylhexylsulphenyl group, nonylsulphenyl group, decylsulphenyl group, 3,7-dimethyloctylsulphenyl group, and laurylsulphenyl group And so on.

The alkylsulphenyl group may have a substituent.
As the "alkylsulphenyl group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are a cycloalkyl group, an alkoxy group, or a cycloalkoxy group. , An aryl group, a group substituted with a fluorine atom or the like, and the like. When the alkylsulfenyl group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9, 1 to 5, or specifically. Examples include 1 to 3 pieces.

The number of carbon atoms of the "cycloalkylsulfenyl group" is usually 3 to 40, preferably 4 to 10.

Examples of the "cycloalkyl sulphenyl group" include a cyclohexyl sul phenyl group.

The number of carbon atoms of the "arylsulphenyl group" is usually 6 to 60, preferably 7 to 48.

Examples of the arylsulfenyl group include a phenylsulphenyl group, a 1-naphthylsulphenyl group, a 2-naphthylsulphenyl group, a 1-anthrasenylsulfenyl group, a 9-anthrasenylsulfenyl group, and a 1-pyrenylsul. Examples include a phenyl group.

The arylsulphenyl group may have a substituent.
As the "arylsulphenyl group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are an alkyl group, a cycloalkyl group, an alkoxy group, and the like. Examples thereof include a cycloalkoxy group, a group substituted with a fluorine atom and the like. When the arylsulfenyl group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9, 1 to 5, or specifically. Examples include 1 to 3 pieces.

A "p-valent heterocyclic group" (p represents an integer of 1 or more) is p of hydrogen atoms directly bonded to a carbon atom or a hetero atom constituting a ring from a heterocyclic compound. It means the remaining atomic group excluding the hydrogen atom of. Among the p-valent heterocyclic groups, it is the remaining atomic group obtained by removing p hydrogen atoms from the hydrogen atoms directly bonded to the carbon atoms or heteroatoms constituting the ring from the aromatic heterocyclic compound. A "p-valent aromatic heterocyclic group" is preferred.

"Aromatic heterocyclic compounds" include oxadiazole, thiadiazole, thiazole, oxazole, thiophene, pyrrole, phosphol, furan, pyridine, pyrazine, pyrimidine, triazine, pyridazine, quinoline, isoquinoline, carbazole, dibenzophosphol and the like. Even if the heterocycle itself does not exhibit aromaticity, and the heterocycle itself such as phenoxazine, phenothiazine, dibenzoborol, dibenzosilol, and benzopyran does not exhibit aromaticity, the aromatic ring is condensed into the heterocycle. Means a compound that is

The number of carbon atoms of the p-valent heterocyclic group is usually 2 to 60, preferably 3 to 20, and more preferably 4 to 20.

Among the p-valent heterocyclic groups, examples of the monovalent heterocyclic group include a thienyl group, a pyrrolyl group, a frill group, a pyridyl group, a piperidinyl group, a quinolinyl group, an isoquinolinyl group, a pyrimidinyl group, a triazinyl group and the like. Be done.

The p-valent heterocyclic group may have a substituent.

As the "monovalent heterocyclic group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are an alkyl group, a cycloalkyl group, or an alkoxy. Examples thereof include a group or a group substituted with a cycloalkoxy group or the like. When the heterocyclic group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted. Specifically, 1 to 9, 1 to 5, or 1 ~ 3 etc. can be mentioned.

The "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

The "amino group" may have a substituent, and in the present embodiment, the substituted amino group is preferable among the amino group and the substituted amino group. As the substituent contained in the "substituted amino group", an alkyl group, a cycloalkyl group, an aryl group or a monovalent heterocyclic group is preferable.

As the substituted amino group, a disubstituted amino group is preferable. Examples of the disubstituted amino group include a dialkylamino group, a dicycloalkylamino group and a diarylamino group. The substituents of the disubstituted amino groups may be bonded to each other to form a ring. The number of carbon atoms of the alkyl group as a substituent of the disubstituted amino group is preferably 1 to 10, more preferably 1 to 6, and further preferably 1 to 4.

Examples of the disubstituted amino group include a dimethylamino group, a diethylamino group, a diphenylamino group, a bis (4-methylphenyl) amino group, a bis (4-tert-butylphenyl) amino group, and a bis (3,5-di) group. -Tert-Butylphenyl) Amino group and the like can be mentioned.

The "alkenyl group" may be either linear or branched. The number of carbon atoms of the linear alkenyl group is usually 2 to 30, preferably 3 to 20. The number of carbon atoms of the branched alkenyl group is usually 3 to 30, preferably 4 to 20.

The number of carbon atoms of the "cycloalkenyl group" is usually 3 to 30, preferably 4 to 20.

Examples of the "alkenyl group" include vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, 3-butenyl group, 3-pentenyl group, 4-pentenyl group, 1-hexenyl group and 5-hexenyl. Groups and 7-octenyl groups are included.

The "alkenyl group" and the "cycloalkenyl group" may have a substituent.
As the "alkenyl group having a substituent" and the "cycloalkenyl group having a substituent", a part or all of the hydrogen atoms in these groups (for example, one to all hydrogen atoms that can be substituted) are substituents. Substituted groups can be mentioned. When the alkenyl group or the cycloalkenyl group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted, specifically, 1 to 9 and 1 to 5. , Or 1 to 3 pieces and the like.

The "alkynyl group" may be either linear or branched. The number of carbon atoms of the alkynyl group is usually 2 to 20, preferably 3 to 20. The number of carbon atoms of the branched alkynyl group is usually 4 to 30, preferably 4 to 20.

The number of carbon atoms of the "cycloalkynyl group" is usually 4 to 30, preferably 4 to 20.

Examples of the "alkynyl group" include ethynyl group, 1-propynyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group, 3-pentynyl group, 4-pentynyl group, 1-hexynyl group, and 5-. Hexinyl groups can be mentioned.

The "alkynyl group" and the "cycloalkynyl group" may have a substituent.
For example, examples of the "alkynyl group having a substituent" include a group in which some or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are substituted with a substituent. When having a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted. Specifically, 1 to 9, 1 to 5, 1, 1 to 3 and the like. Can be mentioned.

The "hydrocarbyl group" is a monovalent group obtained by removing one hydrogen atom from a hydrocarbon compound. For example, the above-mentioned alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group and cycloalkynyl are used. Examples thereof include groups, aryl groups, and combinations of these groups.

Examples of the "hydrocarbylene group" include a divalent group obtained by removing one hydrogen from the above-mentioned "hydrocarbyl group".

The "arylene group" means the remaining atomic group excluding two hydrogen atoms directly bonded to the carbon atoms constituting the ring from the aromatic hydrocarbon. The number of carbon atoms of the arylene group is usually 6 to 60, preferably 6 to 30, and more preferably 6 to 18.

Examples of the "arylene group" include a phenylene group, a naphthalene diyl group, an anthracene diyl group, a phenanthrene diyl group, a dihydrophenanthrene diyl group, a naphthalsendiyl group, a full orangeyl group, a pyrene diyl group, a perylenediyl group, and a chrysendiyl group.

The "arylene group" may have a substituent.
Examples of the "arylene group having a substituent" include a group in which some or all of the hydrogen atoms in these groups (for example, one to all possible hydrogen atoms) are substituted with a substituent. The "arylene group which may have a substituent" is preferably a group represented by the formulas (A-1) to (A-20). When having a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted. Specifically, 1 to 9, 1 to 5, 1, 1 to 3 and the like. Can be mentioned.

[Wherein, R and R ^a each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a monovalent heterocyclic group. R and R ^a there are a plurality, each may be the same or different, bonded R ^a each other to each other, they may form a ring together with the atoms bonded thereto. ]

The number of carbon atoms of the divalent heterocyclic group is usually 2 to 60, preferably 3 to 20, and more preferably 4 to 15.

Examples of the divalent heterocyclic group include pyridine, diazabenzene, triazine, azanaphthalene, diazanaphthalene, carbazole, dibenzofuran, dibenzothiophene, dibenzosilol, phenoxazine, phenothiazine, acridine, dihydroacridine, furan, thiophene and azole. Examples thereof include diazoles or triazoles, which are divalent groups obtained by removing two hydrogen atoms from hydrogen atoms directly bonded to carbon atoms or heteroatoms forming a ring. The divalent heterocyclic group may have a substituent. The "divalent heterocyclic group which may have a substituent" is preferably a group represented by the formulas (AA-1) to (AA-34).

[In the formula, R and ^Ra have the same meanings as above. ]

The "crosslinkable group" can generate a new bond with another atomic group by subjecting it to heating, ultraviolet irradiation, near-ultraviolet irradiation, visible light irradiation, infrared irradiation, radical reaction, or the like. It is a basic group. The crosslinkable group is preferably a group represented by any of the formulas (B-1) to (B-17). These groups may have substituents.

Unless otherwise specified in the present specification, the term "substituent" refers to a halogen atom, a cyano group, an alkyl group, a cycloalkyl group, an aryl group, a monovalent heterocyclic group, an alkoxy group, a cycloalkoxy group and an aryloxy group. Represents a group, amino group, substituted amino group, alkenyl group, cycloalkenyl group, alkynyl group or cycloalkynyl group. The substituent may be a crosslinkable group. In the present embodiment, when a group has a substituent, the number thereof is not limited and can be appropriately selected from 1 to the maximum number that can be substituted. Specifically, 1 to 9 and 1 to 5 The number, 1 to 3, and the like can be mentioned.

<Light emitting element>
The light emitting device according to the present embodiment includes an anode, a light emitting layer, an electron transport layer, and a cathode. In the light emitting device according to the present embodiment, the electron transport layer includes non-conductive particles, an electron transport polymer material having a structural unit represented by the formula (ET-1), and the formula (hh-1). It is a light emitting device containing a non-particulate alkali metal compound represented by.

FIG. 1 is a schematic cross-sectional view of a light emitting device according to an aspect of the present invention. In the light emitting element 1, the anode 11, the light emitting layer 12, the electron transport layer 13, and the cathode 14 are laminated in this order. The electron transport layer 13 is composed of non-conductive particles 15, an electron transport polymer material having a structural unit represented by the formula (ET-1), and a non-particle property represented by the formula (hh-1). It contains a mixture layer 16 with an alkali metal compound.

[Electronic transport layer]
(Non-conductive particles)
In the present embodiment, the non-conductive particles mean particles having an electric conductivity of ^10-6 S / m or less. Examples of the non-conductive particles include non-metal particles, non-metal oxide particles and organic compound particles. As used herein, the non-metallic particles mean non-metallic inorganic particles. Non-metal oxide particles mean non-metal oxide particles. The organic compound particles mean particles of an organic compound.

The non-metal particles in the non-conductive particles may be two or more kinds of non-metal particles, the non-metal oxide particles may be two or more kinds of non-metal oxide particles, and the organic compound particles may be. It may be two or more kinds of organic compound particles. That is, the non-conductive particles may be composed of two or more types of non-metal particles, or may be composed of two or more types of non-metal particles and one type of non-metal oxide particles. When the non-conductive particles are composed of a plurality of types of non-conductive particles, the electrical conductivity of each of the plurality of types of non-conductive particles is ^10-6 S / m or less. For example, when the non-conductive particles are composed of non-metal particles and non-metal oxide particles, the electric conductivity of each of the non-metal particles and the non-metal oxide particles is ^10-6 S / m or less.

The non-conductive particles contained in the electron transport layer preferably have a Z average particle diameter of 500 nm or less, more preferably 300 nm or less, as determined by a dynamic light scattering method, from the viewpoint of improving the element life of the light emitting device. It is preferably 200 nm or less, and more preferably 200 nm or less. It is preferable to set the particle size of the non-conductive particles in the above range because the leakage of electricity of the light emitting element is suppressed.

The non-conductive particles contained in the electron transport layer preferably have a Z average particle diameter of 50 nm or more, more preferably larger than 100 nm, as determined by a dynamic light scattering method, from the viewpoint of improving the element life of the light emitting device. , 120 nm or more is more preferable, and 150 nm or more is particularly preferable.

In this embodiment, the Z average particle size is calculated by a dynamic light scattering method. Specifically, for example, a solution in which particles are dispersed is placed in a measurement cell, irradiated with light having a wavelength of 633 nm, and based on the photon correlation method, Z average particles are obtained from fluctuations in the scattering intensity of the irradiation light, solution viscosity, and temperature. The diameter can be calculated. The Z average particle diameter of the non-conductive particles as a raw material is the same as the Z average particle diameter of the non-conductive particles after being formed as an electron transport layer.

Examples of the organic compound particles include polystyrene particles, polyester particles, melamine particles, polycarbonate particles, phenol resin particles, epoxy particles, and styrene-butadiene rubber particles.

Examples of the non-metal particles include diamond particles and boron particles. Examples of the non-metal oxide particles include silica particles. As the non-conductive particles, polystyrene particles and silica particles are preferable, and silica particles are more preferable.

These non-conductive particles may be solid particles or particles having a void in the center of the particles (for example, hollow particles). The non-conductive particles may be solid particles in only a part of the particles.

These non-conductive particles may be surface-modified in order to improve the dispersibility of the particles. The non-conductive particles may be particles in which only some of the particles are surface-modified.

(Conductive polymer material)
In one aspect shown in FIG. 1, a mixture layer 16 of an electron-transporting polymer and a non-particle-like alkali metal compound is present between the non-conductive particles 15 and the cathode 14.

The electron-transporting polymer material is a polymer compound having a structural unit represented by the above formula (ET-1).

The aromatic hydrocarbon group represented by Ar ^E1 is a group obtained by removing one hydrogen atom nE directly bonded to a carbon atom forming a ring from the arylene group. The heterocyclic group is a group obtained by removing one hydrogen atom nE directly bonded to a carbon atom forming a ring from the divalent heterocyclic group.

The aromatic hydrocarbon group represented by Ar ^E1 is a group obtained by removing the hydrogen atoms (2 + nE1) directly bonded to the carbon atoms constituting the ring from the aromatic hydrocarbons represented by the formulas 1 to 11. Is preferable. The aromatic hydrocarbon group represented by Ar ^E1 is a hydrogen atom (2 + nE1) directly bonded to a carbon atom forming a ring from the aromatic hydrocarbon represented by the formula 1, formula 2, formula 4, formula 5 or formula 7. ) Is more preferable, and the group excluding the hydrogen atom (2 + nE1) directly bonded to the carbon atom constituting the ring from the aromatic hydrocarbon represented by the formulas 1 and 4 is further preferable. ..

If Ar ^E1 is an aromatic hydrocarbon group, the aromatic hydrocarbon group may further have a substituent other than R ^E1. The substituent is not particularly limited.

Examples of the heterocyclic group represented by Ar ^E1 include pyridine, pyrimidine, triazine, pyrazine, pyridazine, quinoline, quinoxalin, carbazole, dibenzofuran, dibenzothiophene, dibenzosilol, 4a, 10a-dihydrophenoxazine, 4a, 10a-. Dihydrophenothiazine, 4a, 9,9a, 10-tetrahydroaclysin, 4a, 5,6a, 7,12,12a, 14,14a-octahydroquinolino [2,3-b] aclydin, pyrrole, furan, thiophene, imidazole, Hydrogen directly bonded to a carbon atom or a hetero atom constituting a ring from a heterocyclic group such as 1,2,4-triazole, oxazole, 1,3,4-oxadiazole, thiazole, or 1,3,4-diazole. Examples include groups excluding the number of atoms (2 + nE1).

If Ar ^E1 is a heterocyclic group, said heterocyclic group may further have a substituent other than R ^E1. The substituent is not particularly limited.

As ^RE1 , a monovalent group containing a hetero atom which may have a substituent may be used because the electron-transporting polymer material has excellent solubility in a polar solvent and can be easily laminated on the light emitting layer. Preferably, the group represented by the formula (9) is more preferable.

_{^{-R E2 (-X 1) m1 ···}} (9)
(In the formula ^{(9), R E2} is (.X ¹ representing the m1 + 1) valent group, .M1 that represents a monovalent group containing a hetero atom, represents an integer of 1 or more.)

nE1 is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2. When nE1 is an integer of 1 to 4, the solubility of the electron-transporting polymer material in the solvent is excellent when the electron-transporting layer is produced by the coating method described later. When the polymer compound has a plurality of structural units represented by the formula (ET-1), the structural units may be the same or different. For example, the electron-transporting polymer material includes a structural unit which is a group derived from an aromatic hydrocarbon represented by the following formula 1 in which Ar ^E1 may have a substituent in the formula (ET-1) and Ar. ^E1 may have a substituent and may have a repeating structure with a structural unit which is a group derived from an aromatic hydrocarbon represented by the formula 4 described later.

The represented (m1 + 1) valent group at R ^E2, for example, a single bond, a hydrocarbyl group or a monovalent heterocyclic group include atomic group remaining after removing m1 hydrogen atoms. Any of the atomic groups may have a substituent. The represented (m1 + 1) valent group at R ^E2, for example, in the case of m1 is 1, the formula -O- _{(R'O) m} - in the group represented by (wherein, R 'is have a substituent Also mentioned are hydrocarbylene groups that may have (eg, alkylene groups that may have substituents).

Represented by R ^E2 (m1 + 1) valent group is preferably an atomic group remaining after removing the m1 hydrogen atoms from an alkyl group which may have a substituent, it may have a substituent From the remaining atomic group with m1 hydrogen atom removed from a good aryl group, the remaining atomic group with m1 hydrogen atom removed from a monovalent heterocyclic group, and the alkyl group substituted with a monovalent heterocyclic group. The remaining atomic group from which m1 hydrogen atom has been removed, or the remaining atomic group from which m1 hydrogen atom has been removed from an aryl group substituted with a monovalent heterocyclic group, more preferably having a substituent. It is the remaining atomic group obtained by removing m1 hydrogen atom from the aryl group which may be used.

As a preferable example of X ^1, a group containing at least one hetero atom selected from the group consisting of a sulfur atom, an oxygen atom, a nitrogen atom and a phosphorus atom is preferable, and a group represented by the formula: −SM, the formula: − Group represented by OM, formula: group represented by -CO ₂ M, formula: group represented by -NM ₂ , formula: group represented by -NRM, formula: represented by -PO ₃ M Group, formula: -OP (= O) (OM) group represented by ₂ , formula: -P (= O) (OM) group represented by ₂ , formula: -C (= O) NM ₂ Group to be, formula: group represented by -C (= O) NRM, formula: group represented by -SO ₃ M, formula: group represented by -SO ₂ M, formula: -NR ₃ M' Group represented by, carboxy group, sulfo group, hydroxyl group, mercapto group, amino group, substituted amino group, cyano group, pyrrolidonyl group, phosphoric acid group, phosphonic acid group, substituted phosphonic acid group, monovalent heterocyclic group, And the groups represented by the formulas (I) to (IX).
R has the same meaning as R above.
M represents an ammonium cation that may have a metal cation or a substituent.
M'represents an anion.

X ¹ is a group represented by the formula: -OM, a group represented by the formula: -CO ₂ M, a group represented by the formula: -SO ₃ M, a group represented by the formula: -SO ₂ M, And a group represented by the formulas (I) to (IX), more preferably, a group represented by the formula: -OM, a group represented by the formula: -CO ₂ M, the formula (I), and more preferably a group represented by formula (II), wherein: -CO 2 group represented by _M, and it is particularly preferably a group represented by the formula (I).

-O- (R'O) _m- R'' (I)

-S- (R'S) _q- R'' (III)
−C (= O) − (R'-C (= O)) _q −R'' (IV)
−C (= S) − (R'−C (= S)) _q −R'' (V)
−N {(R') _q R''} ₂ (VI)
−C (= O) O− (R'−C (= O) O) _q −R'' (VII)
-C (= O) -O- (R'O) _q- R'' (VIII)
−NHC (= O) − (R'NHC (= O)) _q −R'' (IX)
[In formulas (I) to (IX), R'represents a hydrocarbylene group which may have a substituent.
R '' is a hydrogen atom, which may have a substituent hydrocarbyl group, a carboxy group, a sulfo group, a hydroxyl group, a mercapto group, an amino group, a group represented by -NR ^c _2, cyano or -C (= O) Represents a group represented by NR ^c ₂ .
R'''represents a trivalent hydrocarbon group that may have a substituent.
m represents an integer of 1 or more.
q represents an integer greater than or equal to 0.
R ^c represents an alkyl group having 1 to 30 carbon atoms which may have a substituent or an aryl group having 6 to 50 carbon atoms which may have a substituent.
When a plurality of R', R'' and R''' are present, they may be the same or different. ]

The metal cation represented by M is preferably a monovalent, divalent or trivalent ion, for example, Li, Na, K, Cs, Be, Mg, Ca, Ba, Ag, Al, Bi, Cu, Fe. , Ga, Mn, Pb, Sn, Ti, V, W, Y, Yb, Zn, Zr and other metal ions. As the metal cation represented by M, alkali metal ions of Li, Na, K or Cs are preferable.

Examples of the substituent that the ammonium cation represented by M may have include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group and a tert-. Examples thereof include an alkyl group having 1 to 10 carbon atoms such as a butyl group.

Examples of anions represented by M'include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , OH ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , SCN ⁻ , CN ⁻ , and NO _{3 ^{-, SO 4 2-, HSO 4}} -, PO 4 3-, HPO 4 2-, H 2 PO 4 -, BF 4 -, PF 6 -, CH 3 SO 3 -, CF 3 SO 3 -, [(CF ₃ SO ₂ ) ₂ N] ⁻ , tetrakis (imidazolyl) borate anion, 8-quinolinolato anion, 2-methyl-8-quinolinolato anion, 2-phenyl-8-quinolinolato anion and the like.

m1 is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2. When m1 is an integer of 1 to 4, the solubility of the electron-transporting polymer material in the solvent is excellent when the electron-transporting layer is produced by the coating method described later.

Examples of the group represented by the formula ^-R E2 ^(-X _{1) m1,} for example, the formula (2-1) to (2-12), the formula (3-1) to (3-6), and the formula Examples thereof include groups represented by the formulas (4-1) to (4-7).

[In formulas (2-1) to (2-12), M ⁺ represents Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ or N ⁺ (CH ₃ ) ₄ . If there are multiple M ^+'s , they may be the same or different. ]

[In equations (3-1) to (3-6), X ⁻ is F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , B ⁻ (C ₆ H ₅ ) ₄ , CH ₃ COO ⁻ or CF ₃ SO. ₃ ^- represents a. ]

Examples of the polymer compound as an electron-transporting polymer material include JP-A-2009-239279, JP-A-2012-033845, JP-A-2012-216821, JP-A-2012-216822, and JP-A-2012. It can be synthesized according to the method described in -216815.

-Preferable form of the structural unit represented by the formula (ET-1) The structural unit represented by the formula (ET-1) is represented by, for example, formulas (5-1) to (5-31). A structural unit can be mentioned.

[In formulas (5-1) to (5-31), M ⁺ has the same meaning as M ⁺ . ]

The electron-transporting polymer material may further have a structural unit different from the structural unit represented by the formula (ET-1).

The different structural units include the remaining atomic group obtained by removing two hydrogen atoms from the compound having an aromatic ring, the remaining atomic group obtained by removing one hydrogen atom from the hydrocarbyl group, and 1 from the heterocyclic group. The remaining atomic group from which one hydrogen atom has been removed can be mentioned. As the different structural unit, the remaining atomic group obtained by removing two hydrogen atoms from the compound having an aromatic ring and the remaining atomic group obtained by removing one hydrogen atom from the hydrocarbyl group are preferable. More preferably, the remaining atomic group obtained by removing two hydrogen atoms from the compound having the compound.

The polystyrene-equivalent number average molecular weight of the electron-transporting polymer material is preferably 1.0 × 10 ^{3 to} 1.0 × 10 ⁷ because the uniformity of the coating film when the electron-transporting layer is produced by the coating method is excellent. by weight, more preferably from ^{2.0 × 10 3 ~1.0 × 10 6} , more preferably ^{1.0 × 10 4 ~5.0 × 10 5} .

In the light emitting device according to the present embodiment, known electron-transporting polymer materials other than the polymer compound containing the structural unit represented by the formula (ET-1) can be used. Examples of known electron-transporting polymer materials include polyquinoline and its derivatives; polyquinoxaline and its derivatives; and polyfluorene and its derivatives.

The electron transport material may be used alone or in combination of two or more.

(Non-particle alkali metal compound)
In the present embodiment, for the non-particulate alkali metal compound, a solution in which the alkali metal compound is dispersed is placed in a measurement cell, irradiated with light having a wavelength of 633 nm, and the scattering intensity of the irradiation light fluctuates based on the photon correlation method. , The Z average particle size calculated from the solution viscosity and temperature is less than 50 nm.

The non-particle-like alkali metal compound of the present embodiment is a compound represented by the above formula (hh-1).
(M ³ ) _a5 (Z ³ ) _b1 (hh-1)

Examples of the alkali metal cation represented by M ³ include alkali metal cations of Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ and Fr ⁺ , and Na ⁺ , K ⁺ and Cs ⁺ are preferable. Na ⁺ and Cs ⁺ are more preferred, and Cs ⁺ is particularly preferred.

The ^{Z 3, OH -, R p} SO 3 -, R p COO -, R p O -, CO 3 2-, SO 4 2-, HSO 4 -, PO 4 3-, HPO 4 2-, and H ₂ PO ₄ ^- are ^{preferable, OH -, R p COO -} , R p O - and CO ₃ ^2- is more preferable, OH ^- and CO ₃ ^2- is more preferable.

Examples of the monovalent organic group represented by R ^p include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group having 1 to 10 carbon atoms. Alkyl groups; and aryl groups having 6 to 30 carbon atoms such as phenyl groups and 1-naphthyl groups can be mentioned.

Non-particulate alkali metal compounds are metal hydroxides such as LiOH, NaOH, KOH and CsOH; metal halides such as LiF, NaF, KF and CsF; Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ And metal carbonates such as Cs ₂ CO ₃ ; metal carboxylates such as R ^p COOLi, R ^p COONa, R ^p COOK and R ^p COOCs; R ^p SO ₃ Li, R ^p SO ₃ Na, R ^p SO ₃ K , R ^p SO ₃ Cs, Li ₂ SO ₃ , Na ₂ SO ₃ , K ₂ SO ₃ and Cs ₂ SO _{3 and} other metal sulfates; and R ^p OLi, R ^p ONa, R ^p OK and R ^p OCs, etc. It is preferably an alkali metal compound selected from the group consisting of metal alkoxides, preferably metal hydroxides such as LiOH, NaOH, KOH and CsOH, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ and Cs ₂ CO _3. Such as metal carbonates are more preferable.

The compound represented by the formula (hh-1) may be present as a hydrate in the electron transport layer. That is, it may exist as a compound represented by (M ³ ) _a5 (Z ³ ) _b1 · iH ₂ O. Although i differs depending on the compound represented by the formula (hh-1), for example, i is 0 to 10. All of the compounds represented by the formula (hh-1) may be present as hydrates in the electron transport layer, or some of them may be present as hydrates.

When the electron transport layer contains a non-particulate alkali metal compound, the electron transport property is improved when the light emitting element has the non-conductive particles and the electron transport polymer material.

When the electron-transporting polymer material contains a metal cation, the alkali metal contained in the non-particulate alkali metal compound and the metal cation contained in the electron-transporting polymer material may be the same or different, but they are the same. Is preferable.

The electron-transporting polymer material may be adsorbed by the non-conductive particles. When the electron-transporting polymer material is adsorbed on the non-conductive particles, the amount of the electron-transporting polymer material in the vicinity of the non-conductive particles decreases, and the distribution of the electron-transporting polymer material in the electron-transporting layer is poor. It becomes uniform. As a result, the electron transportability of the electron transport layer may decrease.

However, since the electron transport layer contains a non-particle-like alkali metal compound, the influence of the electron-transport polymer material adsorbed on the non-conductive particles can be reduced. Specifically, the non-particle-like alkali metal compound in the electron-transporting layer is adsorbed on the non-conductive particles, so that the adsorption of the electron-transporting polymer material on the non-conductive particles is suppressed. As a result, the electron-transporting polymer material and the non-particle-like alkali metal compound are dispersed in the electron-transporting layer, and the decrease in electron-transporting property can be prevented.

In the electron transport layer, the ratio of the non-conductive particles to 100 parts by mass of the electron transport polymer material is preferably 1 to 200 parts by mass. From the viewpoint of improving the device life, the above ratio is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 50 parts by mass or more. Since the conductivity of the electron transport layer is improved, the above ratio is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, further preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less.

In the electron transport layer, the ratio of the non-particle type alkali metal compound to 100 parts by mass of the electron transport polymer material is preferably 0.1 to 150 parts by mass from the viewpoint of electron transport. The above ratio is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. Since the conductivity of the electron transport layer is improved, the above ratio is preferably 125 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 25 parts by mass or less.

In the electron transport layer, the ratio of the non-conductive particles and the non-particle-like alkali metal compound to 100 parts by mass of the electron transport polymer material is 1 to 200 parts by mass and 0.1 to 150 parts by mass, respectively. It is more preferably 10 to 150 parts by mass and 1 to 125 parts by mass, and further preferably 25 to 100 parts by mass and 5 to 25 parts by mass. When the ratio of the non-conductive particles to 100 parts by mass of the electron-transporting polymer material is 1 to 200 parts by mass, the light extraction efficiency from the light emitting element is improved. When the ratio of the non-particle type alkali metal compound to 100 parts by mass of the electron-transporting polymer material is 0.1 to 150 parts by mass, the electron-transporting property is improved.

The electron transport layer in the light emitting element of the present embodiment may contain two or more types of the non-conductive particles, may contain two or more types of the electron transport polymer material, and may contain the non-particle type alkali. It may contain two or more kinds of metal compounds.

The number of the non-conductive particles per unit area in the electron transport layer, from the viewpoint of improvement of device life, preferably 0.1 or / [mu] m ² or more, more preferably 0.2 pieces / [mu] m ² or more, More preferably, 0.5 pieces / μm ² or more. The number of the non-conductive particles per unit area in the electron-transporting layer is preferably 20 / [mu] m ² or less, more preferably 15 / [mu] m ² or less, 10 pieces / [mu] m ² or less Is more preferable. By setting the number of the non-conductive particles in the above range, the leakage of electricity of the light emitting element is suppressed.

The number of the non-conductive particles per unit area contained in the electron transport layer (sometimes referred to as “particle density” in the present specification) can be calculated by analyzing, for example, by the following method. it can. The surface of a product (that is, a product in which an electron transport layer is laminated on a glass substrate) in which a solution for forming an electron transport layer is formed on a glass substrate, the surface of a light emitting element, or the electrons of a light emitting element in the process of being manufactured. The image is taken by the following method in the direction perpendicular to the plane constituting the light emitting element so as to include the surface of the transport layer.
(I) Analysis is performed using an image obtained by measuring a range of 10 μm × 10 μm with an atomic force microscope.
(Ii) Analysis is performed using an image obtained by measuring a range of 10 μm × 10 μm with a scanning electron microscope.
(Iii) Analysis is performed using an image obtained by optical observation in a range of 10 μm × 10 μm with an optical microscope or a microscope.

There are variations in the distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode. The thickness of the thinnest portion of the electron transport layer is 1 nm to 500 nm, preferably 2 nm to 300 nm, and more preferably 5 nm to 100 nm. The thickness of the thickest portion of the electron transport layer is 110 nm to 1 μm, preferably 120 nm to 500 nm, and more preferably 130 nm to 350 nm. Here, the non-conductive particles may be present in the thickest portion of the electron transport layer.

The electron transport layer is in contact with the cathode, and the root mean square roughness of the interface between the electron transport layer and the cathode is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 15 nm or more. preferable. As will be described later, when the cathode has a multilayer structure, the electron transport layer is in contact with the electron injection layer closest to the light emitting layer among the plurality of cathode layers.

The root mean square roughness (RMS) of the interface between the electron transport layer and the cathode is preferably 80 nm or less, more preferably 60 nm or less, and particularly preferably 50 nm or less from the viewpoint of improving the device life. The root mean square roughness is obtained, for example, as follows. First, using an atomic force microscope, the surface of a product (that is, a product in which an electron transport layer is laminated on a glass substrate) in which a solution for forming an electron transport layer is formed on a glass substrate, the surface of a light emitting element, Alternatively, the image is taken in the direction perpendicular to the plane constituting the light emitting element so as to include the surface of the electron transport layer of the light emitting element in the process of being manufactured. In the obtained image, the calculation interval is 10 μm × 10 μm, and the root mean square roughness in the calculation interval can be obtained. In addition, for example, the surface of a product in which a solution for forming an electron transport layer is formed on a glass substrate, the surface of a light emitting element, or the surface of an electron transport layer of a light emitting element in the process of being manufactured may be included. Examples thereof include a method of obtaining from an image taken with a laser microscope and a method of obtaining from the measurement result of a stylus type surface measuring meter.

The maximum height difference between the electron transport layer and the cathode is preferably 50 nm or more, more preferably 80 nm or more, and further preferably 100 nm or more from the viewpoint of improving the device life.

The maximum distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode is preferably 300 nm or less, more preferably 250 nm or less, and further preferably 200 nm or less. By setting the maximum distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode within the above range, leakage of the current of the light emitting element is suppressed, which is preferable. The maximum distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode is preferably 20 nm or more, more preferably 50 nm or more, and more preferably 80 nm from the viewpoint of improving the light extraction efficiency. The above is more preferable.

The maximum distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode is determined by, for example, using an atomic force microscope to deposit a solution for forming the electron transport layer on a glass substrate. A plane constituting the light emitting element so as to include the surface of the object (that is, the object in which the electron transport layer is laminated on the glass substrate), the surface of the light emitting element, or the surface of the electron transport layer of the light emitting element being manufactured. Take a picture in the vertical direction. In the obtained image, the calculation section is 10 μm × 10 μm, and the maximum value of the distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode in the calculation section or the interface between the electron transport layer and the light emitting layer. The maximum distance in the previous period can be obtained by measuring the maximum value of the distance from the electron transport layer to the surface of the electron transport layer. In addition, for example, a method of obtaining the surface of the light emitting element or the electron transport layer before forming the cathode from an image obtained by using a laser microscope, and a method of obtaining from the measurement result of a stylus type surface measuring instrument can be mentioned. ..

[Light emitting layer]
In the present embodiment, the light emitting layer may be a layer containing a light emitting material. Luminescent materials are classified into low molecular weight compounds and high molecular weight compounds. The light emitting material may be a high molecular compound or a low molecular compound. The luminescent material may have a crosslinkable group and may be crosslinked by a crosslinkable group.

Low molecular weight compounds used as luminescent materials include, for example, naphthalene and its derivatives; anthracene and its derivatives; perylene and its derivatives; and triplet luminescent complexes having iridium, platinum or europium as the central metal (that is, phosphorescent luminescent complex). Material).

Examples of the polymer compound used as a luminescent material include a phenylene group, a naphthalenediyl group, a fluoranyl group, a phenanthreneyl group, a dihydrophenanthreneyl group, a carbazolediyl group, a phenoxazinediyl group, a phenothiazinediyl group, and an anthracendiyl group. , Or a high molecular compound containing a pyrenedyl group or the like.

In the present embodiment, the light emitting material preferably contains a triplet light emitting complex.
As the triplet luminescent complex, an iridium complex such as a metal complex represented by the formulas Ir-1 to Ir-5 is preferable.

[In the formula, R ^{D1 to} R ^D8 , R ^{D11 to} R ^D20 , R ^{D21 to} R ^D26 and R ^{D31 to} R ^D37 are independently hydrogen atoms, alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkoxy groups, respectively. Represents an aryl group, an aryloxy group, a monovalent heterocyclic group or a halogen atom, and a part or all of the hydrogen atom in these groups except the hydrogen atom and the halogen atom (for example, 1 to all possible hydrogen atoms to be substituted). ) May be substituted with a substituent. When a plurality of R ^{D1 to} R ^D8 , R ^{D11 to} R ^D20 , R ^{D21 to} R ^D26 and R ^{D31 to} R ^D37 exist, they may be the same or different from each other.
-A ^D1 --- ^{A D2} - represents a bidentate ligand of the ^{anionic, A D1} and ^{A D2} represent each independently, a carbon atom is bound to an iridium atom, an oxygen atom or a nitrogen atom, they The atom of may be an atom constituting a ring. When there are a plurality of −A ^D1 −−A ^D2− , they may be the same or different.
n ^D1 represents 1, 2 or 3, and n ^D2 represents 1 or 2. ]

Examples of the anionic bidentate ligand represented by −A ^D1 −−A ^D2 − include ligands represented by the formulas (6-1) to (6-6).

[In formulas (6-1) to (6-6), * represents a site that binds to Ir. ]

Examples of the triplet luminescent complex include the following metal complexes.

In the present embodiment, the light emitting material may be used alone or in combination of two or more.

In the present embodiment, the light emitting layer preferably contains a host material together with the light emitting material. Host materials are classified into low molecular weight compounds and high molecular weight compounds. The host material may be a high molecular weight compound or a low molecular weight compound.

The low molecular weight compound used as the host material includes a compound having a carbazole skeleton, a compound having a triarylamine skeleton, a compound having a phenanthroline skeleton, a compound having a triaryltriazine skeleton, a compound having an azole skeleton, and a benzothiophene skeleton. Examples thereof include compounds, compounds having a benzofurene skeleton, compounds having a fluorene skeleton, compounds having a spirofluorene skeleton, and the like, and examples thereof are compounds represented by formulas (7-1) to (7-11). ..

As the polymer compound used as the host material (hereinafter, also referred to as “polymer host”), those used as the host material of the light emitting layer can be widely used in the technical field to which the present invention belongs. In one aspect of the present invention, for example, a polymer compound containing a structural unit represented by the formula (Y) can be preferably mentioned.

[In the formula, Ar ^Y1 represents an arylene group, a divalent heterocyclic group, or a divalent group in which an arylene group and a divalent heterocyclic group are directly bonded, and a part of hydrogen atoms in these groups. Alternatively, all (for example, one to all substitutable hydrogen atoms) may be substituted with a substituent. ]

The polymer host may be any of a block copolymer, a random copolymer, an alternating copolymer, and a graft copolymer, and may be in other embodiments, but may contain a plurality of types of raw material monomers. It is preferably a copolymer obtained by copolymerizing.

The polymer host can be produced using a known polymerization method described in Chemical Review (Chem. Rev.), Vol. 109, pp. 897-1091 (2009) and the like. Examples of the method for producing the polymer host include a method of polymerizing by a coupling reaction using a transition metal catalyst such as Suzuki reaction, Yamamoto reaction, Buchwald reaction, Stille reaction, Negishi reaction and Kumada reaction.

In the polymerization method, as a method of charging the monomers, a method of collectively charging the entire amount of the monomers into the reaction system, a method of charging a part of the monomers and reacting them, and then collectively and continuously charging the remaining monomers. Alternatively, a method of separately charging, a method of continuously or dividing the monomer, and the like can be mentioned.

Examples of the transition metal catalyst include a palladium catalyst, a nickel catalyst and the like.

The post-treatment of the polymerization reaction is carried out by a known method, for example, a method of removing water-soluble impurities by liquid separation, a reaction solution after the polymerization reaction is added to a lower alcohol such as methanol, the precipitated precipitate is filtered, and then dried. The method of making the mixture may be used alone or in combination. When the purity of the polymer host is low, it can be purified by a usual method such as crystallization, reprecipitation, continuous extraction with a Soxhlet extractor, or column chromatography. In the present embodiment, the host material may be used alone or in combination of two or more.

The thickness of the light emitting layer is usually 5 nm to 1 μm, preferably 10 nm to 500 nm, and more preferably 30 nm to 200 nm. The thickness of the light emitting layer is determined by, for example, the following method. A light emitting layer is formed on a glass plate by a thin film deposition method or a coating method using a procedure for forming a light emitting layer in a process of manufacturing an element. On the glass substrate on which the light emitting layer is formed, the step between the part with the light emitting layer and the part without the light emitting layer is measured using a stylus type step meter, and the average value between arbitrary 10 points is taken as the thickness of the light emitting layer. can do.

[electrode]
The light emitting device according to this embodiment has an anode and a cathode.
Examples of the material of the anode include conductive metal oxides and translucent metals, preferably indium oxide, zinc oxide, tin oxide (NESA, etc.); indium tin oxide (ITO), indium. Conductive compounds such as zinc and oxide; composites of silver, palladium and copper (APC); gold, platinum, silver and copper.

In the light emitting device according to the present embodiment, the cathode may have a single layer structure made of a single material or a plurality of materials, or may have a multilayer structure made of a plurality of layers. When the cathode has a single-layer structure, the material of the cathode includes, for example, low-resistance metals such as gold, silver, copper, aluminum, chromium, tin, lead, nickel, and titanium and alloys containing these; tin oxide, zinc oxide. , Indium oxide, ITO, indium zinc oxide (IZO), conductive metal oxides such as molybdenum oxide; and mixtures of these conductive metal oxides with metals, and alloys containing aluminum and aluminum are preferred. In the case of a multi-layer structure, in the present specification, the layer closest to the light emitting layer side among the plurality of cathode layers constituting the cathode is referred to as a first cathode layer (also referred to as an electron injection layer). Then, the layer next to the first cathode layer is referred to as a second cathode layer, the layer next to the second cathode layer is referred to as a third cathode layer, and the like.

When the cathode according to the present embodiment has an electron injection layer, the material of the electron injection layer includes, for example, an alkali metal, an alkaline earth metal, an alloy containing one or more of the metals; an oxide of the metal, Examples thereof include one or more materials selected from the group consisting of halides, carbonates, and composite oxides; and mixtures thereof.

Examples of alkali metals or oxides thereof, halides, carbonates and composite oxides include lithium, sodium, potassium, rubidium, cesium, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide and lithium fluoride. Examples include sodium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, potassium molybdate, potassium titanate, potassium tungstate, and cesium molybdenate. ..

Examples of alkaline earth metals or their oxides, halides, carbonates and composite oxides include magnesium, calcium, strontium, barium, magnesium oxide, calcium oxide, strontium oxide, barium oxide, magnesium fluoride and calcium fluoride. , Barium fluoride, barium fluoride, magnesium carbonate, calcium carbonate, barium carbonate, barium carbonate, barium molybdate, and barium tungstate.

Examples of alloys containing one or more alkali metals or alkaline earth metals include Li-Al alloys, Mg-Ag alloys, Al-Ba alloys, Mg-Ba alloys, Ba-Ag alloys, and Ca-Bi-Pb-. Sn alloys can be mentioned.

A composition containing both the material exemplified as the cathode layer material and the material exemplified above as the material constituting the electron injection layer can also be used for the electron injection layer. From the viewpoint of electron supply capacity, the work function of the material of the electron injection layer is preferably 3.5 eV or less. In the present embodiment, as the material of the electron injection layer, metal oxides, fluorides, carbonates, composite oxides and the like having a work function of 3.5 eV or less can also be preferably used. The materials of these electron injection layers may be used alone or in combination of two or more. Examples of the material of the layer after the electron injection layer, that is, the layer laminated on the electron injection layer such as the second cathode layer, are the same as the material of the electron injection layer.

When the cathode has a multi-layer structure, as an example of the material of each cathode layer, a metal having a low resistivity and a high body corrosiveness to water, a metal oxide, or the like is preferably used. More specifically, low resistance metals such as gold, silver, copper, aluminum, chromium, tin, lead, nickel, and titanium; alloys containing the low resistance metals; metal nanoparticles; metal nanowires; tin oxide, oxidation. Conductive metal oxides such as zinc, indium oxide, ITO, IZO, and molybdenum oxide; a mixture of the conductive metal oxide and a metal; nanoparticles of the conductive metal oxide; graphene, fullerene, carbon nanotubes, etc. Conductive carbon of. As the material used in each layer constituting each cathode layer, one type from the above may be used alone, or two or more types may be used in combination.

In the present embodiment, the light emitting device preferably has an electron injection layer, for example, a two-layer structure of an electron injection layer and a second cathode layer, or three of an electron injection layer, a second cathode layer, and a third cathode layer. A layered structure is preferred. Examples of the case where the light emitting element according to the present embodiment has an electron injection layer include Mg / Al, Ca / Al, Ba / Al, NaF / Al, KF / Al, RbF / Al, CsF / Al, and Na ₂ CO. Two-layer structure of electron injection layer such as ₃ / Al, K ₂ CO ₃ / Al, and Cs ₂ CO ₃ / Al and first cathode layer, LiF / Ca / Al, NaF / Ca / Al, NaF / Mg / Ag, KF / Ca / Al, RbF / Ca / Al, CsF / Ca / Al, Ba / Al / Ag, KF / Al / Ag, KF / Ca / Ag, and _K 2 _CO 3 / Ca / Ag and the like electrons Examples thereof include a three-layer structure of an injection layer, a first cathode layer and a second cathode layer. Here, the symbol "/" indicates that the layers are in contact with each other. It is preferable that the material of the second cathode layer has a reducing action on the material of the electron injection layer. Here, the presence or absence and degree of the reducing action between the materials can be estimated from, for example, the bond dissociation energy (ΔrH °) between the compounds. That is, in the case of a combination in which the bond dissociation energy is positive in the reduction reaction of the material constituting the second cathode layer with respect to the material constituting the electron injection layer, the material of the second cathode layer is relative to the material of the electron injection layer. It can be said that it has a reducing action.

The bond dissociation energy can be referred to, for example, in "Electrochemical Handbook 5th Edition" (Maruzen, 2000) and "Thermodynamic Database MALT" (Science and Technology, 1992).

The anode and the cathode may each have a laminated structure of two or more layers, or may have a structure patterned in a mesh shape.

As a method for producing the electrode, a known method can be used, and examples thereof include a vacuum deposition method, a sputtering method, an ion plating method, and a method of forming a film from a solution (a mixed solution with a polymer binder may be used). Will be done. When a light emitting device is formed by a roll-to-roll method, it is preferable to use a method of forming a film from a solution.

The light emitting element according to this embodiment may be formed on a substrate. The substrate may be a substrate that can form an electrode (anode or cathode) on one surface thereof and does not chemically change when an organic layer (light emitting layer and electron transport layer) is formed.

The substrate may be, for example, a substrate made of a material such as glass, plastic, or silicon. The substrate may be transparent, translucent or opaque, and when the substrate is opaque, the electrode farthest from the substrate is preferably transparent or translucent.

When the light emitting element is manufactured by the roll-to-roll method, a substrate made of a plastic material is preferable because it has excellent flexibility. Examples of the plastic material include polyethylene naphthalate (PEN), polyether fulphon, polyethylene terephthalate, and polycarbonate, which are excellent in heat resistance, coefficient of thermal expansion, and water absorption. Therefore, a substrate made of PEN material. Is preferable.

The light emitting device according to the present embodiment may further have a layer other than the above. For example, the light emitting device may further have a hole injection layer, a hole transport layer, and the like.

[Hole injection layer]
The hole injection layer is a layer that is in contact with the anode and has a function of receiving holes from the anode, and further has a function of transporting holes as needed and a function of supplying holes to the light emitting layer. And a layer having any of the functions of a barrier against electrons injected from the cathode. The hole transport layer is a layer mainly having a function of transporting holes, and further, if necessary, a function of receiving holes from the anode, a function of supplying holes to the light emitting layer, and injection from the cathode. A layer that has any of the functions that act as a barrier to electrons.

In the light emitting element according to the present embodiment, as the material for forming the hole injection layer, carbazole and its derivative; triazole and its derivative; oxazole and its derivative; oxadiazol and its derivative; imidazole and its derivative; Derivatives; polyarylalkane and its derivatives; pyrazoline and its derivatives; pyrazolone and its derivatives; phenylenediamine and its derivatives; arylamine and its derivatives; starburst-type amines; phthalocyanine and its derivatives; amino-substituted chalcones and their derivatives; Styrylanthracene and its derivatives; fluorenone and its derivatives; hydrazone and its derivatives; stilben and its derivatives; silazane and its derivatives; aromatic tertiary amine compounds; styrylamine compounds; aromatic dimethyridin-based compounds; porphyrin-based compounds; polysilane-based Compounds; poly (N-vinylcarbazole) and its derivatives; organic silanes and their derivatives; and polymers containing them; oxidation of conductive metals such as vanadium oxide, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide. Derivatives; Conductive polymers and oligomers such as polyaniline, aniline-based copolymers, thiophene oligomers, and polythiophenes; organic conductive materials such as poly (3,4-ethylenedioxythiophene), polystyrene sulfonic acid, and polypyrrole, and these. Polymers containing; amorphous carbon; tetracyanoquinodimethane and its derivatives (eg, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), 1,4-naphthoquinone and Derivatives thereof, diphenoquinone and its derivatives, and acceptor organic compounds such as polynitro compounds; or silane coupling agents such as octadecyltrimethoxysilane can be preferably used.

These materials may be used as a single component or as a composition composed of a plurality of components.
The hole injection layer may have a single-layer structure composed of only these materials, or may have a multi-layer structure composed of a plurality of layers having the same composition or different compositions. Materials exemplified as materials that can be used in the hole transport layer described later can also be used in the hole injection layer.

When an organic compound layer such as a hole transport layer and a light emitting layer is formed following the hole injection layer, particularly when both layers are formed by a coating method, the previously applied layer is applied later. It may not be possible to form a laminated structure by dissolving in the solvent contained in the solution of the layer. In this case, a method of insolubilizing the lower layer with a solvent can be used.

As a method of solvent insolubilization, a method of attaching a crosslinkable group to a high molecular compound and crosslinking it to insolubilize it, or a method of mixing a low molecular weight compound having a crosslinkable group having an aromatic ring represented by aromatic bisazide as a crosslinking agent is used. A method of cross-linking and insolubilizing, a method of mixing a low molecular weight compound having a cross-linking group having no aromatic ring represented by an acryloyl group as a cross-linking agent, cross-linking and insolubilizing, and exposing the lower layer to ultraviolet light to cross-link. Examples thereof include a method of insolubilizing the organic solvent used in the production of the upper layer, a method of heating and cross-linking the lower layer, and a method of insolubilizing the organic solvent used in the production of the upper layer.

When the lower layer is heated, the heating temperature is usually 100 ° C. to 300 ° C., and the heating time is usually 1 minute to 1 hour.

Other than cross-linking, there is a method of using solutions of different polarities for producing adjacent layers as another method of laminating without dissolving the lower layer. For example, a water-soluble polymer compound is used for the lower layer and oil-soluble is used for the upper layer. There is a method of preventing the lower layer from being dissolved even if it is applied by using the polymer compound of.

The optimum value for the thickness of the hole injection layer differs depending on the material used, and it may be selected so that the drive voltage, luminous efficiency, and device life are appropriate values, but a thickness that does not cause pinholes is required. If it is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the thickness of the hole injection layer is usually 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 10 nm to 100 nm. The thickness of the hole injection layer is measured by the same method as the thickness of the light emitting layer, except that the distance from the interface between the anode and the hole injection layer to the interface between the hole transport layer and the hole injection layer is measured. can do.

[Hole transport layer]
In the light emitting element according to the present embodiment, as the material constituting the hole transport layer, for example, carbazole and its derivative; triazole and its derivative; oxazole and its derivative; oxadiazole and its derivative; imidazole and its derivative; And its derivatives; polyarylalkane and its derivatives; pyrazoline and its derivatives; pyrazolone and its derivatives; phenylenediamine and its derivatives; arylamines and their derivatives; amino-substituted chalcones and their derivatives; styrylanthracene and its derivatives; fluorenone and its derivatives Hydrazone and its derivatives; Stilben and its derivatives; Silazane and its derivatives; Aromatic tertiary amine compounds; Styrylamine compounds; Aromatic dimethidyldin-based compounds; Porphyrin-based compounds; Polysilane-based compounds; Poly (N-vinylcarbazole) and Examples thereof include organic silanes and derivatives thereof; and polymers containing these structures; conductive polymers and oligomers such as aniline copolymers, thiophene oligomers, and polythiophenes; and organic conductive materials such as polypyrrole.

These materials may be a single component or a polymer compound composed of a plurality of components.
The hole transport layer may have a single-layer structure composed of only these materials, or may have a multi-layer structure composed of a plurality of layers having the same composition or different compositions. Materials exemplified as materials that can be used in the hole injection layer can also be used in the hole transport layer.

When an organic layer such as a light emitting layer is formed by a coating method following the hole transport layer, if the lower layer is dissolved in a solvent contained in the solution of the layer to be coated later, a hole injection layer is formed. The lower layer can be solvent insoluble in a manner similar to that illustrated in the method.

The optimum value of the thickness of the hole transport layer differs depending on the material used, and it may be selected so that the drive voltage and the element life are appropriate values. However, the thickness must be such that pinholes do not occur, but if it is too thick, the drive voltage of the element will increase. Therefore, the thickness of the hole transport layer is usually 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 100 nm. The thickness of the hole transport layer is the same as the thickness of the light emitting layer, except that the distance from the interface between the hole injection layer and the hole transport layer to the interface between the light emitting layer and the hole transport layer is measured. Can be measured.

As the material used for the hole transport layer, a light emitting material exemplified in the light emitting layer, a material having a crosslinkable group attached to the light emitting material, or the like may be used.

Preferred layer configurations of the light emitting device according to the present embodiment include, for example, the following configurations. (A) Anode-Light emitting layer-Electron transport layer-Cathode (b) Anode-Hole injection layer-Light emitting layer-Electron transport layer-Cathode (c) Anode-Hole injection layer-Hole transport layer-Light emitting layer-Electrons Transport layer-cathode

The light emitting device according to the present embodiment may be provided with an insulating layer in contact with the electrode in order to improve the adhesion to the electrode and / or the charge injection from the electrode, but the electron transport layer and the cathode are in contact with each other. Is preferable. A thin buffer layer may be inserted at the interface between the hole transport layer and the light emitting layer or the interface between the electron transport layer and the light emitting layer in order to improve the adhesion of the interface and / or prevent mixing. The order and number of layers to be laminated and the thickness of each layer may be adjusted in consideration of luminous efficiency and device life.

The light emitting device according to the present embodiment can be manufactured, for example, by sequentially laminating each layer on a substrate. Specifically, for example, an anode is provided on the substrate, a layer such as a hole injection layer and a hole transport layer is provided on the substrate, a light emitting layer is provided on the anode, and an electron transport layer is provided on the light emitting layer. Further, a light emitting element can be manufactured by laminating a cathode on the cathode.

As another manufacturing method, a cathode is provided on the substrate, layers such as an electron transport layer, a light emitting layer, a hole transport layer, and a hole injection layer are provided on the cathode, and an anode is laminated on the cathode. , A light emitting element can be manufactured.

As yet another manufacturing method, the anode-side base material in which each layer is laminated on the anode or the anode and the cathode-side base material in which each layer is laminated on the cathode or the cathode are joined to face each other. Can be done.
Either a vacuum vapor deposition method or a coating method may be used for laminating each layer.

In the present embodiment, it is preferable to form the electron transport layer by the coating method. For example, the method for manufacturing a light emitting device according to one aspect of the present invention is a method for manufacturing a light emitting device having a step of forming an anode, a light emitting layer, an electron transport layer, and a cathode, and the electron transport layer is formed by a coating method. A method for manufacturing the light emitting element, which comprises a step. More specifically, a composition containing an electron-transporting polymer material, non-conductive particles, and a non-particle-like alkali metal compound is prepared, and the composition is formed onto a light emitting layer by a coating method. , Form an electron transport layer.

The solvent used in the coating method may be any solvent that can dissolve or uniformly disperse the material used for forming the layer. Examples of the solvent include chlorine-based solvents such as 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, and o-dichlorobenzene; ether-based solvents such as THF, dioxane, anisole, and 4-methylanisol; Aromatic hydrocarbons such as toluene, xylene, mesitylene, ethylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene cyclohexylbenzene, trimethylbenzene, and 3-phenoxytoluene. Solvents; aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, and bicyclohexyl; acetone, Ketone solvents such as methyl ethyl ketone, cyclohexanone, and acetophenone; ester solvents such as ethyl acetate, butyl acetate, ethyl cell solve acetate, methyl benzoate, and phenyl acetate; ethylene glycol, glycerin, 1,2-hexanediol and the like. Polyhydric alcohol solvents; alcohol solvents such as methanol, ethanol, isopropyl alcohol, 1-butanol, tert-butyl alcohol, and cyclohexanol; sulfoxide solvents such as dimethyl sulfoxide; N-methyl-2-pyrrolidone, and N, Amid solvents such as N-dimethylformamide, 2,2,3,3-tetrafluoropropanol, 1,1,1-trifluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-propanol, 2,2,3,3,4,4-hexafluorobutanol, 2,2,3,3,4,5,4-heptafluoro-1-butanol, 2,2,3,3,3 -Pentafluoro-1-propanol, 3,3,4,5,5,5-heptafluoro-2-pentanol, 2,2,3,3,4,5,5-octafluoro-1 -Pentanol, 3,3,4,5,5,6,6,6-nonafluoro-1-hexanol, and 2,2,3,3,4,5,5,6,6,7 , 7-Dodecafluoroheptanol and other fluorinated alcohol solvents, water and the like. The solvent may be used alone or in combination of two or more.

When the electron transport layer is formed by the coating method, it is preferable that the non-conductive particles and the non-particle alkaline metal compound contained in the electron transport layer can be dispersed in the solvent used in the coating method. From the viewpoint of improving the dispersibility of the non-conductive particles in the solvent, the non-conductive particles are dispersed in the solvent used in the coating method, the non-particulate alkali metal compound is added and mixed, and finally the electron transportability is achieved. It is preferable to mix the polymer materials to prepare the composition. In order to improve the dispersibility of the non-conductive particles in the solvent, the non-conductive particles may be surface-modified.

Examples of the film forming method include spin coating method, casting method, microgravure printing method, gravure printing method, bar coating method, roll coating method, wire bar coating method, dip coating method, slit coating method, cap coating method, and spraying. Examples thereof include a coating method, a screen printing method, a flexo printing method, an offset printing method, an inkjet printing method, and a nozzle coating method, and it is preferable to use the slit coating method and the inkjet printing method.

In the coating liquid, the blending amount of the solvent is usually 1000 to 100,000 parts by mass, preferably 2000 to 20000 parts by mass with respect to 100 parts by mass of the material used for forming the layer.

The method for forming the layer other than the electron transport layer is not particularly limited, and a known method may be used. When the material used for forming each layer is a low molecular weight compound, it can be formed by, for example, a vacuum vapor deposition method from powder, a film formation method from a solution or a molten state, or the like. When the material used for forming each layer is a polymer compound, it can be formed by, for example, a method of forming a film from a solution or a molten state.

<Distribution of alkali metal elements in the electron transport layer>
As described above, the electron-transporting polymer material may be adsorbed on the non-conductive particles, but if the non-particle-like alkali metal compound is dispersed in the electron-transporting layer, the electron-transporting property of the electron-transporting layer becomes The decrease can be suppressed.

Examples of a method for detecting an alkali metal element dispersed in an electron transport layer include energy dispersive X-ray spectroscopy (EDX) using a transmission electron microscope (TEM).

As a parameter that defines the distribution of the layer of alkali metal elements, the full width at half maximum (FWHM) of the peak obtained from the EDX line profile by TEM measured by the following method is adopted in the present specification. In the light emitting element according to one aspect of the present invention, the line profile of EDX by TEM for the alkali metal element in the electron transport layer shows a peak, and the full width at half maximum (FWHM) of the peak is 18 nm or more and 55 nm or less. preferable. The full width at half maximum here is different from the distance from the interface between the electron transport layer and the light emitting layer to the interface between the electron transport layer and the cathode.

A specific method for deriving the full width at half maximum of the peak will be described below. First, the EDX measurement field is determined by observing a cross section in a direction parallel to the stacking direction of the light emitting elements (in other words, from the anode to the cathode) using TEM. The EDX measurement field of view is a square field of view with a magnification of 300,000 times and a side of 460 nm, includes an anode, a light emitting layer, an electron transport layer, and a cathode, and is in contact with the center of the nearest non-conductive particles from the center of the field of view. Select so that the distance is 3 times or more and 11 times or less the diameter of the non-conductive particles. The center of the non-conductive particles is the intersection of the diameter in the direction parallel to the stacking direction of the light emitting element and the diameter in the direction perpendicular to the stacking direction of the light emitting element by observing the particle cross section with TEM.

The reason for selecting the EDX measurement field of view so that the distance from the center of the field of view to the center of the nearest non-conductive particles is 3 times or more and 11 times or less the diameter of the non-conductive particles is as follows. Since the metal cations are adsorbed on the non-conductive particles, the distribution of the metal cations in the vicinity of the non-conductive particles becomes non-uniform. Therefore, if the EDX measurement field of view is set so as to include the vicinity of the non-conductive particles, the data will vary, and it will be difficult to ensure reproducibility. If the distance from the center of the field of view to the center of the nearest non-conductive particles is 3 to 11 times the diameter of the non-conductive particles, there is almost no effect of adsorption of metal cations on the non-conductive particles. No, data reproducibility can be ensured.

The element mapping image of the measurement field of view is acquired by EDX, line analysis is performed in a direction parallel to the stacking direction of the elements (in other words, the direction from the anode to the cathode), and a line profile averaged over the entire field of view is obtained. Of the line profiles, the line profile of the alkali metal element in the electron transport layer has a peak derived from the alkali metal element in the electron transport layer.

The full width at half maximum of this peak is preferably 18 nm to 55 nm, more preferably 19 nm to 50 nm, and even more preferably 20 nm to 40 nm. The full width at half maximum of the peak is preferable because the electron injection property and the electron transport property are optimized. When the full width at half maximum of the peak is 18 nm or more, the electron injection property becomes good. When the full width at half maximum of the peak is 55 nm or less, the electron transportability is good.

The full width at half maximum of this peak can be obtained as follows. The line profile is smoothed by the adjacent average. From the obtained line profile, the minimum intensity of the region from the interface between the anode and the light emitting layer to the interface between the light emitting layer and the electron transport layer is obtained. The minimum intensity is subtracted from the intensity of all data points in the line profile (baseline setting). For the peak of the obtained new line profile, the distance at which the intensity is half the intensity of the peak top is determined for both sides of the peak, and the difference between the distances is defined as the full width at half maximum (FWHM).

The region from the interface between the anode and the light emitting layer to the interface between the light emitting layer and the electron transport layer may include only the light emitting layer, or may further include, for example, a hole injection layer and a hole transport layer in addition to the light emitting layer. May be. In that case, the minimum strength of the region from the interface between the anode and the hole injection layer or the hole transport layer in contact with the anode to the interface between the light emitting layer and the electron transport layer is obtained.

<Use>
The light emitting element of the present invention can be used for, for example, lighting and a display.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

<Measurement of NMR>
The NMR measurement was carried out by dissolving about 10 mg of the measurement sample in about 0.7 mL of deuterated solvent and using an NMR apparatus (manufactured by Agent, trade name: INOVA300 or MERCURY 400VX).

<Measurement of TLC-MS>
For the measurement of TLC-MS, the measurement sample is dissolved in toluene, tetrahydrofuran or chloroform at an arbitrary concentration, coated on a TLC plate for DART (manufactured by Techno Applications, trade name: YSK5-100), and TLC-MS (Japan). This was performed using a product name: JMS-T100TD (The AccuTOF TLC) manufactured by JEOL Ltd. The helium gas temperature at the time of measurement was adjusted in the range of 200 to 400 ° C.

<Analysis by HPLC>
A value of high performance liquid chromatography (HPLC) area percentage was used as an index of the purity of the compound. Unless otherwise specified, this value is a value at 254 nm by HPLC (manufactured by Shimadzu Corporation, trade name: LC-20A). At this time, the compound to be measured was dissolved in tetrahydrofuran or chloroform so as to have a concentration of 0.01 to 0.2% by mass, and 1 to 10 μL was injected into HPLC depending on the concentration. Acetonitrile and tetrahydrofuran were used as the mobile phase of HPLC, and the flow was performed by gradient analysis of acetonitrile / tetrahydrofuran = 100/0 to 0/100 (volume ratio) at a flow rate of 1 mL / min. As the column, SUMPAX ODS Z-CLUE (manufactured by Sumika Chemical Analysis Service) or an ODS column having equivalent performance was used. A photodiode array detector (manufactured by Shimadzu Corporation, trade name: SPD-M20A) was used as the detector.

<Liquid chromatograph mass spectrometry>
In liquid chromatography-mass spectrometry (LC-MS), the measurement sample is dissolved in chloroform or THF to a concentration of about 2 mg / mL, and about 1 μL is injected into LC-MS (manufactured by Azilent Technology, trade name: 1100LCMSD). , LC-MS was used for the mobile phase while changing the ratio of acetonitrile and THF, and the flow was carried out at a flow rate of 0.2 mL / min. As a column, SUMIPAX ODS Z-CLUE (φ4.6 × 250 mm, 3 μm, manufactured by Sumika Chemical Analysis Service) was used.

<Molecular weight analysis by GPC>
The polystyrene-equivalent number average molecular weight (Mn) and the polystyrene-equivalent weight average molecular weight (Mw) of the polymer compound were determined by the following size exclusion chromatography (SEC) using tetrahydrofuran as the moving layer. The measurement conditions of SEC are as follows.
The polymer compound to be measured was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into SEC. The mobile phase was run at a flow rate of 0.6 mL / min. As a column, one each of TSKguardcolum SuperAW-H, TSKgel SuperAWM-H, and TSKgel SuperAW3000 (all manufactured by Tosoh) was connected in series and used. A UV-VIS detector (manufactured by Tosoh, trade name: UV-8320GPC) was used as the detector.

<Z average particle size measurement>
The Z average particle size is measured by dispersing the particles of the measurement sample with a dispersible solvent so as to have a concentration of about 1% by mass or less, and using a zetasizer (manufactured by Malvern, trade name: Zetasizer Nano ZS). It was.

<Measurement of root mean square (RMS), maximum height difference, particle density>
Root mean square, maximum height difference, number of non-conductive particles per unit area in the electron transport layer (In the present specification, the number of non-conductive particles per unit area is also referred to as "particle density". The measurement was performed by the following method.
A solution for forming the electron transport layer is formed on a glass substrate so as to have the same thickness as the electron transport layer in the light emitting element, and then an atomic force microscope is used so as to include the surface of the electron transport layer. The image was taken in the direction perpendicular to the interface between the electron transport layer and the glass substrate. In the obtained image, the calculation section was set to 10 μm × 10 μm, and the root mean square roughness, the maximum height difference, and the number of non-conductive particles per unit area in the electron transport layer were determined.

<EDX measurement by TEM>
Using FIB (manufactured by Hitachi High-Technologies Corporation, trade name: FB2200), the light emitting device was sliced in a direction parallel to the stacking direction so that the thickness of the section was 150 nm. Observe the cross section of the flaky light emitting element with TEM (manufactured by JEOL Ltd., trade name: JEM-2200FS), and by EDS (manufactured by JEOL Ltd., trade name: JED-2300), the full width of the peak of the alkali metal element. Was calculated as follows.

Using a TEM, the cross section of the light emitting device was observed in a square field of view with an acceleration voltage of 200 kV, a magnification of 300,000 times, and a side of 460 nm. The field of view to be observed includes an anode, a light emitting layer, an electron transporting layer and a cathode, and the distance from the center of the field to the center of the nearest non-conductive particles is 3 times or more and 11 times or less the diameter of the non-conductive particles. It was selected to be. The center of the non-conductive particles was defined as the intersection of the diameter in the direction parallel to the stacking direction of the light emitting elements and the diameter in the direction perpendicular to the stacking direction of the light emitting elements by observing the cross section of the non-conductive particles with TEM.

An element mapping image was acquired from the field of view by EDX (duel time: 0.5 msec, number of integrations: 50 times), line analysis was performed in a direction parallel to the stacking direction of the light emitting elements, and lines averaged over the entire field of view. I got a profile. Among the line profiles, the line profile of cesium, which is an alkali metal element in the electron transport layer, showed a peak derived from cesium, which is an alkali metal element in the electron transport layer. The full width at half maximum of the peak was determined as follows.

The line profile was smoothed by the adjacent average. From the obtained line profile, the minimum intensity of the region from the interface between the anode and the hole injection layer to the interface between the light emitting layer and the electron transport layer was determined. The minimum intensity was subtracted from the intensity of all data points in the line profile. For the obtained new line profile, a distance that was half the intensity of the peak was obtained for both sides of the peak, and the difference between the distances was defined as the full width at half maximum.

<Synthesis Example 1> Synthesis of Monomers CM1 to CM6 Monomers CM1 to CM6 were synthesized according to the methods described in the following documents, and those each showing an HPLC area percentage value of 99.5% or more were used. ..
Monomer CM1 was synthesized according to the method described in JP2012-033845A.
Monomer CM2 was synthesized according to the method described in JP-A-2010-189630.
The monomers CM3 to CM5 were synthesized according to the method described in International Publication No. 2013/146806.
Monomer CM6 was synthesized according to the method described in WO 2009/157424.

<Synthesis Example 2> Synthesis of Polymer Compound E1 After setting the inside of the reaction vessel to an inert gas atmosphere, monomeric CM1 (9.23 g), monomeric CM2 (4.58 g), and dichlorobis (tris-o-methoxy) Phenylphosphine) Palladium (8.6 mg) and toluene (175 mL) were added and heated to 105 ° C. Then, a 12 mass% sodium carbonate aqueous solution (40.3 mL) was added dropwise thereto, and the mixture was refluxed for 29 hours. Then, phenylboronic acid (0.47 g) and dichlorobis (tris-o-methoxyphenylphosphine) palladium (8.7 mg) were added thereto, and the mixture was refluxed for 14 hours.

Then, an aqueous sodium diethyldithiacarbamate solution was added thereto, and the mixture was stirred at 80 ° C. for 2 hours. When the obtained reaction solution was cooled and then added dropwise to methanol, precipitation occurred. The precipitate was collected by filtration, washed with methanol and water, dried, and the solid obtained was dissolved in chloroform and purified by passing it through an alumina column and a silica gel column which had been previously passed with chloroform. When the obtained purified liquid was added dropwise to methanol and stirred, precipitation occurred. The precipitate was collected by filtration and dried to obtain polymer compound P1 (7.15 g). The molecular weight of the polymer compound P1 was 3.2 × 10 ^{4 for} Mn and 6.0 × 10 ⁴ for Mw.

In the theoretical value obtained from the amount of the charged raw material, the polymer compound P1 is composed of a structural unit derived from the monomer CM1 and a structural unit derived from the monomer CM2 in a molar ratio of 50:50. It is a copolymer made of.

After setting the inside of the reaction vessel under an argon gas atmosphere, the polymer compound P1 (3.1 g), tetrahydrofuran (130 mL), methanol (66 mL), cesium hydroxide monohydrate (2.1 g) and water (12.5 mL) ) Was added, and the mixture was stirred at 60 ° C. for 3 hours. Then, methanol (220 mL) was added thereto, and the mixture was stirred for 2 hours. After concentrating the obtained reaction mixture, the mixture was added dropwise to isopropyl alcohol and stirred to form a precipitate. The precipitate was collected by filtration and dried to obtain polymer compound E1 (3.5 g). By ¹ H-NMR analysis of the polymer compound E1, it was confirmed that the signal of the ethyl ester moiety in the polymer compound P1 disappeared and the reaction was completed. The molecular weight of the polymer compound E1 is the same as that of the polymer compound P1.

In the theoretical value obtained from the amount of the raw material charged in the polymer compound P1, the polymer compound E1 has 50 structural units represented by the formula (8-1) and 50 structural units derived from the monomer CM2. It is a copolymer composed of a molar ratio of: 50.

<Synthesis Example 3> Synthesis of Polymer Compound H1 After creating an inert gas atmosphere in the reaction vessel, monomeric CM3 (2.52 g), monomeric CM4 (0.47 g), and monomeric CM5 (4. 90 g), monomeric CM6 (0.53 g), and toluene (158 mL) were added and heated to 95 ° C. A 20 mass% tetraethylammonium hydroxide aqueous solution (16 mL) and dichlorobis (tris-o-methoxyphenylphosphine) palladium (4.2 mg) were added to the reaction mixture, and the mixture was refluxed for 8 hours. After the reaction, phenylboronic acid (0.12 g), 20 mass% tetraethylammonium hydroxide aqueous solution (16 mL), and dichlorobis (tris-o-methoxyphenylphosphine) palladium (4.2 mg) were added thereto, and the mixture was refluxed for 15 hours. I let you. Then, an aqueous sodium diethyldithiacarbamate solution was added thereto, and the mixture was stirred at 85 ° C. for 2 hours. After cooling, the reaction solution was washed twice with a 3.6 mass% hydrochloric acid aqueous solution, twice with a 2.5 mass% ammonia aqueous solution, and four times with water, and the obtained solution was added dropwise to methanol to cause precipitation. It was. The precipitate was dissolved in toluene and purified by passing it through an alumina column and a silica gel column in this order. The obtained solution was added dropwise to methanol, stirred, and then the obtained precipitate was collected by filtration and dried to obtain polymer compound H1 (6.02 g). The molecular weight of the polymer compound H1 is, Mn is 3.8 × 10 ^4, Mw was 4.5 × 10 ^5.

According to the theoretical value obtained from the amount of the charged raw material, the polymer compound H1 has a structural unit derived from the monomer CM3, a structural unit derived from the monomer CM4, and a configuration derived from the monomer CM5. It is a copolymer in which the unit and the structural unit derived from the monomeric CM6 are composed of a molar ratio of 40:10:47: 3.

<Synthesis Example 4> Synthesis of Phosphorescent Compounds 1 and 2 Phosphorescent compounds 1 and 2 were synthesized according to the methods described in the following documents, and each showed an HPLC area percentage value of 99.5% or more. Using.
Phosphorescent compound 1 was synthesized according to the method described in International Publication No. 2006/1218111.
Phosphorescent compound 2 was synthesized according to the method described in WO 2009/131255.

<Synthesis Example 5> Synthesis of polystyrene particles A After the flask is placed in an inert atmosphere, 10 g (64 mmol) of 4,4'-bipyridyl is mixed with 100 mL of dichloromethane, heated and stirred until dissolved, and then at room temperature (25 ° C.). The same applies hereinafter.) A solid was precipitated by dropping 5 mL (80 mmol) of methyl iodide dissolved in 50 mL of dichloromethane. The reaction mixture was stirred at room temperature overnight, filtered, and washed with dichloromethane. The obtained solid was dried under reduced pressure overnight in a vacuum dryer at 50 ° C. to obtain 13.11 g of low molecular weight compound 1.

After the flask was placed under the inert atmosphere, 13 g (43 mmol) of the low molecular weight compound 1 was weighed, mixed with 600 mL of acetonitrile, heated and stirred at 80 ° C. until dissolved, and then cooled to room temperature. By dropping 21.5 mL (154 mmol) of 4-chloromethylstyrene and heating at 60 ° C. for 65 hours, a red precipitate was generated. The precipitate was filtered off and washed with acetonitrile. The obtained solid was dried under reduced pressure overnight in a vacuum dryer at 50 ° C. to obtain 16.71 g of low molecular weight compound 2.

After the flask is placed in an inert atmosphere, 5.2 g (49.9 mmol) of styrene, 0.65 g (4.99 mmol) of divinylbenzene and 0.22 g (0.49 mmol) of low molecular weight compound 2 are weighed and 99 mL is used. After dissolving in pure water, bubbling was carried out with nitrogen for 1 hour.
After adding 0.27 g (1.00 mmol) of 2,2'-azobis (2-methylpropionamidin) dihydrochloride dissolved in 1 mL of pure water, the mixture was heated and stirred at 80 ° C. for 14 hours. The reaction solution was allowed to cool, placed in a dialysis membrane (Spectra / Pro 4), sealed, and purified using pure water for 7 days to obtain about 100 mL of a dispersion of polystyrene particles A. The Z average particle diameter of the obtained polystyrene particles A was 102 nm.

<Synthesis Example 6> Synthesis of Polystyrene Particle B In Synthesis Example 5, the polystyrene particles B were dispersed in the same manner as in Synthesis Example 5, except that the amount of the low molecular weight compound 2 used was changed to 0.045 g (0.1 mmol). About 100 mL of the liquid was obtained. The Z average particle diameter of the obtained polystyrene particles B was 155 nm.

<Example 1> Fabrication and evaluation of light emitting device D1 (i) Formation of anode and hole injection layer An anode was formed by attaching an ITO film to a glass substrate with a thickness of 45 nm by a sputtering method. A hole injection material (ND-3202) manufactured by Nissan Chemical Industries, Ltd. was formed on the anode to a thickness of 35 nm by a spin coating method. The substrate on which the hole injection material was formed was heated on a hot plate at 50 ° C. for 3 minutes to volatilize the solvent, and then heated on a hot plate at 240 ° C. for 15 minutes to form a hole injection layer. ..

(Ii) Formation of Hole Transport Layer The polymer compound H1 was dissolved in xylene at a concentration of 0.65% by mass. Using the obtained xylene solution, a hole was formed on the hole injection layer by a spin coating method to a thickness of 20 nm, and the holes were heated on a hot plate at 180 ° C. for 60 minutes in a nitrogen gas atmosphere. A transport layer was formed.

(Iii) Formation of light-emitting layer Toluene contains a low-molecular-weight compound X (manufactured by Luminescence Technology, LT-N4013), a phosphorescent compound 1, and a phosphorescent compound 2 (mass ratio: low-molecular-weight compound X). / Phosphorescent compound 1 / Phosphorescent compound 2 = 74/25/1) was dissolved at a concentration of 2.0% by mass to prepare a toluene solution. Using this toluene solution, a film was formed on the hole transport layer to a thickness of 75 nm by a spin coating method, and a light emitting layer was formed by heating at 130 ° C. for 10 minutes in a nitrogen gas atmosphere.

(Iv) Formation of electron transport layer 2,2,3,3,4,5,5-octafluoro-1-pentanol, silica particles A (QSG-170 manufactured by Shin-Etsu Chemical Industry Co., Ltd., Z average particles) (Diameter 199 nm) was dispersed, cesium hydroxide monohydrate was added, and the polymer compound E1 was added to obtain a dispersion liquid for forming an electron transport layer in which the polymer compound E1 had a concentration of 0.2% by mass. .. The dispersion liquid for forming an electron transport layer is formed on the light emitting layer by a spin coating method so that the polymer compound E1 has a thickness of 10 nm, and heated at 130 ° C. for 10 minutes in a nitrogen gas atmosphere. An electron transport layer was formed. The mass of the non-conductive particles is 50 parts by mass and the mass of the alkali metal compound is 15 parts by mass with respect to 100 parts by mass of the polymer compound E1 which is an electron transporting polymer material in the electron transport layer.

(V) Formation of cathode After placing the substrate on which the electron transport layer was formed in the vapor deposition machine and reducing the pressure to 1.0 × 10 ^-4 Pa or less, sodium fluoride was placed on the electron transport layer as a cathode at about 4 nm. Then, aluminum was deposited on it at about 200 nm. Then, the light emitting element D1 was manufactured by sealing with a glass substrate.

<Comparative Example 1> Preparation and Evaluation of Light Emitting Element CD1 A light emitting device CD1 was produced in the same manner as in Example 1 except that silica particles A were not blended in the electron transport layer.

<Examples 2 to 11> Preparation and evaluation of light emitting elements D2 to D11 Concentration (mass%) of the polymer compound E1 used in the dispersion liquid for forming an electron transport layer, and each non-conductive particle (referred to as a particle in the table). ), The mass part of the non-conductive particles with respect to 100 parts by mass of the polymer compound E1, the type of the alkali metal compound, and the mass part of the alkali metal compound with respect to 100 parts by mass of the polymer compound E1 are shown in Table 1. A light emitting element was produced in the same manner as in Example 1 except that it was changed to one. Here, as the silica particles B, MA-ST-2040 manufactured by Nissan Chemical Industries, Ltd. and a Z average particle diameter of 291 nm were used.

(Vi) Evaluation of light emitting element EL light emission was observed by applying a current to the light emitting element. The device is driven by the density of particles in the electron transport layer (pieces / μm ² ), the root mean square roughness (RMS) (nm) of the surface of the electron transport layer, and the current value at which the front luminance of the light emitting element becomes 12000 cd / m ^2. The element life (time) until the front luminance is reduced to 70% of the initial value is measured, and the element life (time) of the light emitting element CD1 (Comparative Example 1) is set to 100 as a relative value and light emission. Table 1 shows the luminous efficiency (cd / A) when the front luminance of the element is 1000 cd / m ² . Further, FIGS. 2 to 12 are photographs of the electron transport layers obtained in Examples 1 to 11 formed on a glass substrate by an atomic force microscope image. FIG. 13 is a photograph of the electron transport layer obtained in Comparative Example 1 formed on a glass substrate by an atomic force microscope image.

It was found that the light emitting devices D1 to D11 of Examples 1 to 11 containing silica particles or polystyrene particles in the electron transport layer had a longer element life than the light emitting device CD1 of Comparative Example 1 containing no non-conductive particles. Further, it was found that the light emitting elements D1 to D11 of Examples 1 to 11 have high luminous efficiency.

(Vii) Distribution of alkali metals in the electron transport layer With respect to Examples 1, 2, 6 and 8, the above-mentioned <TEM] was used for the alkali metal elements in the electron transport layer by energy dispersive X-ray spectroscopy of a transmission electron microscope. Line profile analysis was performed by the method of EDX measurement>, and the half-value full width of the peak in the line profile was measured. The light emitting element D1 of Example 1 was selected so that the distance from the center of the field of view to the center of the nearest non-conductive particles was 5 times the diameter of the non-conductive particles. The light emitting element D2 of the second embodiment is carried out except that the field of view to be observed is selected so that the distance from the center of the field of view to the center of the nearest non-conductive particles is three times the diameter of the non-conductive particles. The half-value full width was obtained in the same manner as in the light emitting element D1 of Example 1. The light emitting element D6 of the sixth embodiment is carried out except that the field of view to be observed is selected so that the distance from the center of the field of view to the center of the nearest non-conductive particles is 5 times the diameter of the non-conductive particles. The half-value full width was obtained in the same manner as in the light emitting element D1 of Example 1. The light emitting element D8 of the eighth embodiment is carried out except that the field of view to be observed is selected so that the distance from the center of the field of view to the center of the nearest non-conductive particles is 10 times the diameter of the non-conductive particles. The half-value full width was obtained in the same manner as in the light emitting element D1 of Example 1.

The full width at half maximums obtained for the light emitting devices D1, D2, D6 and D8 were 24.6 nm, 27.1 nm, 27.8 nm and 35.3 nm, respectively.

According to the present invention, it is possible to provide a light emitting device having an excellent device life.

1 ... light emitting element, 11 ... anode, 12 ... light emitting layer, 13 ... electron transport layer, 14 ... cathode, 15 ... non-conductive particles, 16 ... mixture layer.

Claims (11)

A light emitting element in which an anode, a light emitting layer, an electron transport layer, and a cathode are arranged in this order, and the electron transport layer has non-conductive particles and a structural unit represented by the formula (ET-1). A light emitting element containing an electron-transporting polymer material and a non-particulate alkali metal compound represented by the formula (hh-1).
[In equation (ET-1), nE1 represents an integer of 1 or more.
Ar ^E1 represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
^RE1 may have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, and a substituent. Represents an alkoxy group, a cycloalkoxy group which may have a substituent, an aryloxy group which may have a substituent, or a monovalent group containing a hetero atom which may have a substituent. .. When there are a plurality of ^RE1 , they may be the same or different. ]
(M ³ ) _a5 (Z ³ ) _b1 (hh-1)
[In formula (hh-1), M ³ represents an alkali metal cation. If M ³ is plurally present, they may be the same or different.
Z ^{3 is, F -, Cl -, Br} -, I -, OH -, B (R p) 4 -, R p SO 3 -, R p COO -, R p O -, ClO -, ClO 2 -, _{^{ClO 3 -, ClO 4 -,}} SCN -, CN -, NO 3 -, CO 3 2-, SO 4 2-, HSO 4 -, PO 4 3-, HPO 4 2-, H 2 PO 4 -, BF 4 ^- or PF ₆ ^- is. R ^p is a monovalent organic group having 1 to 15 carbon atoms. When a plurality of R ^ps exist, they may be the same or different.
a5 and b1 are each independently an integer of 1 or more. However, a5 and b1 are selected so that the charge of the alkali metal compound represented by the formula (hh-1) becomes 0. ] The light emitting device according to claim 1, wherein the Z average particle diameter of the non-conductive particles is larger than 100 nm and 300 nm or less. The light emitting device according to claim 1 or 2, wherein the non-conductive particles include at least one of silica particles and polystyrene particles. The light emitting device according to any one of claims 1 to 3, wherein the ratio of the non-conductive particles is 1 to 200 parts by mass with respect to 100 parts by mass of the electron-transporting polymer material. The light emission according to any one of claims 1 to 4, wherein the ratio of the non-particle-like alkali metal compound is 0.1 to 150 parts by mass with respect to 100 parts by mass of the electron-transporting polymer material. element. The light emitting device according to any one of claims 1 to 5, wherein the number of the non-conductive particles per unit area in the electron transport layer is 0.2 particles / μm ² or more. The light emitting device according to any one of claims 1 to 6, wherein the cathode and the electron transport layer are in contact with each other, and the root mean square roughness of the interface between the cathode and the electron transport layer is 5 nm or more. The light emitting device according to any one of claims 1 to 7, wherein the electron-transporting polymer material contains a metal cation. The light emitting device according to claim 8, wherein the metal cation is a cation of M ^{3 in} the formula (hh-1). The line profile of the energy dispersive X-ray spectroscopy of the transmission electron microscope for the alkali metal element in the electron transport layer shows a peak, and the half-value total width of the peak is 18 nm or more and 55 nm or less, claims 1 to 9. The light emitting element according to any one item. A method for manufacturing a light emitting element in which an anode, a light emitting layer, an electron transport layer, and a cathode are arranged in this order, wherein the electron transport layer is composed of non-conductive particles and represented by the formula (ET-1). It contains an electron-transporting polymer material having a unit and a non-particulate alkali metal compound represented by the formula (hh-1).
The non-conductive particles, the electron-transporting polymer material having a structural unit represented by the formula (ET-1), and the non-particle-like alkali metal compound represented by the formula (hh-1). A method for producing a light emitting element, which comprises a step of applying a composition containing and to form the electron transport layer.
[In equation (ET-1), nE1 represents an integer of 1 or more.
Ar ^E1 represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
^RE1 may have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, and a substituent. Represents an alkoxy group, a cycloalkoxy group which may have a substituent, an aryloxy group which may have a substituent, or a monovalent group containing a hetero atom which may have a substituent. .. When there are a plurality of ^RE1 , they may be the same or different. ]
(M ³ ) _a5 (Z ³ ) _b1 (hh-1)
[In formula (hh-1), M ³ represents an alkali metal cation. If M ³ is plurally present, they may be the same or different.
Z ^{3 is, F -, Cl -, Br} -, I -, OH -, B (R p) 4 -, R p SO 3 -, R p COO -, R p O -, ClO -, ClO 2 -, _{^{ClO 3 -, ClO 4 -,}} SCN -, CN -, NO 3 -, CO 3 2-, SO 4 2-, HSO 4 -, PO 4 3-, HPO 4 2-, H 2 PO 4 -, BF 4 ^- or PF ₆ ^- is. R ^p is a monovalent organic group having 1 to 15 carbon atoms. When a plurality of R ^ps exist, they may be the same or different.
a5 and b1 are each independently an integer of 1 or more. However, a5 and b1 are selected so that the charge of the alkali metal compound represented by the formula (hh-1) becomes 0. ]