KR20240007066A - High molecular weight compound and organic electroluminescent device using same - Google Patents

Abstract

(Project) To provide a polymer material that has excellent hole injection and transport performance, has electron blocking ability, and is highly stable in a thin film state. Additionally, to provide an organic EL device that has an organic layer (thin film) formed of the polymer material, has high luminous efficiency, and has a long lifespan.
(Solution) It is a high molecular weight compound containing a triarylamine structural unit having a fluorene ring and a triarylamine structural unit having a dibenzofuran ring, dibenzothiophene ring, or carbazole ring in the molecular main chain. The high molecular weight compound preferably contains a thermally crosslinkable structural unit in the molecular main chain.

Description

High molecular weight compounds and organic electroluminescence devices using them

The present invention relates to high molecular weight compounds suitable for organic electroluminescence devices (organic EL devices), which are self-luminous devices suitable for various display devices, and organic EL devices using these high molecular weight compounds.

Because organic EL devices are self-luminous devices, they are brighter than liquid crystal devices, have excellent visibility, and enable clear displays, so active research has been conducted on them.

Organic EL elements have a structure in which a thin film (organic layer) of an organic compound is sandwiched between an anode and a cathode. Methods for forming thin films are broadly divided into vacuum deposition and coating methods. Vacuum deposition is a technique that mainly uses low-molecular-weight compounds to form a thin film on a substrate in a vacuum, and is a technology that has already been put into practical use. On the other hand, the coating method mainly uses polymer compounds and is a method of forming a thin film on a substrate using a solution such as inkjet or printing. It has high material use efficiency, is suitable for large areas and high definition, and is expected to be used in the future. It is an essential technology for area organic EL displays.

The vacuum deposition method using low-molecular materials has extremely low material usage efficiency, and when enlarged, the warpage of the shadow mask increases, making uniform deposition on a large substrate difficult. It also faces the problem of increased manufacturing costs.

On the other hand, polymer materials can form a uniform film even on large-sized substrates by applying a solution dissolved in an organic solvent, and coating methods such as inkjet or printing can be used to utilize this. Therefore, it becomes possible to increase the efficiency of material use, and the manufacturing cost for device manufacturing can be significantly reduced.

Until now, various organic EL devices using polymer materials have been examined, but there has been a problem that device characteristics such as luminous efficiency and lifespan are not necessarily sufficient (for example, see Patent Document 1 to Patent Document 5).

In addition, a fluorene polymer called TFB has been known so far as a representative hole transport material in organic EL devices using polymer materials (see Patent Document 6 to Patent Document 7). However, since TFB had insufficient hole transport properties and insufficient electron blocking properties, there was a problem in that some electrons escaped the light emitting layer and no improvement in luminous efficiency could be expected. In addition, since film adhesion to adjacent layers was low, there was a problem that longer life of the device could not be expected.

Japanese Patent Publication No. 2005-272834 Japanese Patent Publication No. 2007-119763 Japanese Patent Publication No. 2007-162009 Japanese Patent Publication No. 2007-177225 International Publication No. 2005/049546 Japanese Patent Publication No. 4375820 International Publication No. 2005/059951

The purpose of the present invention is to provide a polymer material that has excellent hole injection and transport performance, has electron blocking ability, and is highly stable in a thin film state. Additionally, the object is to provide an organic EL device that has an organic layer (thin film) formed of the polymer material, has high luminous efficiency, and has a long lifespan.

The present inventors focused on the fact that high molecular weight compounds containing a triarylamine structural unit having a fluorene ring in the molecular main chain have high hole injection and transport capabilities and can also be expected to form a wide gap, and have developed various triarylamine structures. As a result of synthesizing and examining high molecular weight compounds containing units, the present invention was completed.

That is, the present invention is as described below.

[1] A high molecular weight compound comprising a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and having a weight average molecular weight of 10,000 or more and less than 1,000,000 in terms of polystyrene.

During the ceremony,

R ₁ and R ₃ are each independently a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a halogen atom, or an alkyl group, an alkyloxy group, a cycloalkyl group, a cycloalkyloxy group, an alkenyl group, or an alkyl group having 40 or less carbon atoms. Represents an aryloxy group.

a, b and c are the following integers.

a = 0, 1, 2 or 3

b = 0, 1, 2, 3 or 4

c = 0 or 1

R ₂ each independently represents an alkyl group, an alkyloxy group, or a cycloalkyl group having 3 to 40 carbon atoms.

L represents a phenylene group, and n represents an integer of 0 to 3.

X each independently represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group.

Y is an oxygen atom (O), a sulfur atom (S), or a group represented by the following formula (3).

R ₄ in the formula represents a substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group.

[2] The high molecular weight compound according to [1], wherein in the general formulas (1) and (2), R ₁ and R ₃ are hydrogen atoms.

[3] The high molecular weight compound according to [1] or [2], wherein in the general formula (1), R ₂ is an alkyl group having 3 to 40 carbon atoms.

[4] In the above general formulas (1) and (2), The high molecular weight compound according to [1] or [2], which is an indenocarbazolyl group or an acridinyl group.

[5] A high molecular weight compound according to [1] or [2], comprising a repeating unit having a thermally crosslinkable structural unit Q represented by the following general formula (4).

During the ceremony,

R ₃ , X and a all have the same definition as shown in General Formula (1).

[6] The high molecular weight compound according to [5], wherein in the general formula (4), the heat crosslinkable structural unit Q is a structure represented by the following general formulas (5a) to (5af).

R ₁ , R ₂ , a and b in the above general formulas (5a) to (5af) all have the same definitions as those shown in general formula (1).

[7] An organic electroluminescence device having a pair of electrodes and an organic layer sandwiched between them, wherein the organic layer uses the high molecular weight compound according to [1] or [2] as a constituent material. Nesence element.

[8] The organic electroluminescence device according to [7], wherein the organic layer is a hole transport layer.

[9] The organic electroluminescence device according to [7], wherein the organic layer is an electron blocking layer.

[10] The organic electroluminescence device according to [7], wherein the organic layer is a hole injection layer.

[11] The organic electroluminescence device according to [7], wherein the organic layer is a light-emitting layer.

The high molecular weight compound of the present invention described above is,

(1) Good hole injection characteristics,

(2) The mobility of holes is large,

(3) Wide gap and excellent electromagnetic blocking ability

It has characteristics.

The organic layer formed of such a high molecular weight compound is preferably used as a hole transport layer, an electron blocking layer, a hole injection layer, or a light emitting layer, and an organic EL device using the organic layer is,

(1) High luminous efficiency and power efficiency,

(2) the practical driving voltage is low;

(3) Long life

It has an advantage.

That is, the high molecular weight compound of the present invention has a high hole transport ability and an excellent electron blocking ability, and is therefore excellent as a compound for application-type organic EL devices. By producing a coating-type organic EL device using the compound, high luminous efficiency and power efficiency can be obtained, and durability can be improved.

1 shows the chemical structure of preferred repeating units 1-1 to 1-6 as repeating unit A represented by general formula (1) of the present invention.
Figure 2 shows the chemical structure of preferred repeating units 1-7 to 1-12 as repeating unit A represented by general formula (1) of the present invention.
Figure 3 shows the chemical structure of preferred repeating units 1-13 to 1-18 as repeating unit A represented by general formula (1) of the present invention.
Figure 4 shows the chemical structure of preferred repeating units 1-19 to 1-24 as repeating unit A represented by general formula (1) of the present invention.
Figure 5 shows the chemical structure of preferred repeating units 1-25 to 1-28 as repeating unit A represented by general formula (1) of the present invention.
Figure 6 shows the chemical structure of preferred repeating units 2-1 to 2-6 as repeating unit B represented by general formula (2) of the present invention.
Figure 7 shows the chemical structure of preferred repeating units 2-7 to 2-12 as repeating unit B represented by general formula (2) of the present invention.
Figure 8 shows the chemical structure of repeating units 2-13 to 2-18 preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 9 shows the chemical structure of repeating units 2-19 to 2-24 preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 10 shows the chemical structure of preferred repeating units 2-25 to 2-30 as repeating unit B represented by general formula (2) of the present invention.
Figure 11 shows the chemical structure of preferred repeating units 2-31 to 2-36 as repeating unit B represented by general formula (2) of the present invention.
Figure 12 shows the chemical structure of repeating units 2-37 to 2-42 preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 13 shows the chemical structure of preferred repeating units 2-43 to 2-48 as repeating unit B represented by general formula (2) of the present invention.
Figure 14 shows the chemical structure of repeating units 2-49 to 2-54 preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 15 shows the chemical structure of preferred repeating units 2-55 to 2-60 as repeating unit B represented by general formula (2) of the present invention.
Figure 16 shows the chemical structure of repeating units 2-61 to 2-66 preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 17 shows the chemical structure of repeating units 2-67 to 2-68, which are preferred as repeating unit B represented by general formula (2) of the present invention.
Figure 18 shows the chemical structures of substituents 1 to 24 preferred as X in formulas (1), (2), and (4) in the present invention.
Figure 19 shows the chemical structures of substituents 25 to 48 preferred as X in formulas (1), (2), and (4) in the present invention.
Figure 20 is an example of the layer structure of the organic EL device of the present invention.
Figure 21 is a ¹ H-NMR chart of high molecular weight compound I of Example 1.

＜Repetition Unit A and Repetition Unit B＞

The high molecular weight compound of the present invention includes a repeating unit A represented by the following general formula (1), and a repeating unit B represented by the following general formula (2).

During the ceremony,

R ₁ and R ₃ are each independently a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a halogen atom, or an alkyl group, an alkyloxy group, a cycloalkyl group, a cycloalkyloxy group, an alkenyl group, or an alkyl group having 40 or less carbon atoms. Represents an aryloxy group.

a, b and c are the following integers.

a = 0, 1, 2 or 3

b = 0, 1, 2, 3 or 4

c = 0 or 1

R ₂ each independently represents an alkyl group, an alkyloxy group, or a cycloalkyl group having 3 to 40 carbon atoms.

L represents a phenylene group, and n represents an integer of 0 to 3.

X each independently represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group.

Y is an oxygen atom (O), a sulfur atom (S), or a group represented by the following formula (3).

R ₄ in the formula represents a substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group.

Halogen atoms represented by R ₁ and R ₃ in the general formulas (1) and (2) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, and aryloxy group having 40 or less carbon atoms represented by R ₁ and R ₃ are, respectively, an alkyl group with 1 to 8 carbon atoms and an aryloxy group with 1 to 8 carbon atoms. An alkyloxy group, a cycloalkyl group with 5 to 10 carbon atoms, a cycloalkyloxy group with 5 to 10 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, and an aryloxy group with 6 to 10 carbon atoms are preferable.

The following groups can be exemplified as the alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, and aryloxy group.

Alkyl group (carbon number: 1 to 8); Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, neo Hexyl group, n-heptyl group, isoheptyl group, neoheptyl group, n-octyl group, isooctyl group, neooctyl group, etc.

Alkyloxy group (carbon number: 1 to 8); Methyloxy group, ethyloxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, tert-butyloxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n -Octyloxy group, etc.

Cycloalkyl group (carbon number: 5 to 10); Cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, etc.

Cycloalkyloxy group (carbon number: 5 to 10); Cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group, 1-adamantyloxy group, 2-adamantyloxy group, etc.

Alkenyl group (carbon number: 2 to 6); Vinyl group, allyl group, isopropenyl group, 2-butenyl group, etc.

Aryloxy group (carbon number: 6 to 10); Phenyloxy group, tolyloxy group, etc.

In the high molecular weight compound of the present invention, since synthesis is easy, it is preferable that R ₃ in the general formula (1) and R ₃ in the general formula (2) are the same group.

Moreover, it is preferable that both R ₁ and R ₃ in the general formulas (1) and (2) are hydrogen atoms.

Examples of the alkyl group, alkyloxy group, and cycloalkyl group having 3 to 40 carbon atoms represented by R ₂ in the general formula (1) include the same groups as the above-mentioned groups.

In the high molecular weight compound of the present invention, in order to increase solubility, R ₂ is preferably an alkyl group with 3 to 40 carbon atoms, more preferably an alkyl group with 3 to 10 carbon atoms, and n-hexyl or n-octyl group. Most desirable.

Examples of the monovalent aryl group and monovalent heteroaryl group represented by X in the general formulas (1) and (2) include the following groups.

Aryl group; Phenyl group, naphthyl group, anthracenyl group, phenanthrenyl group, fluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, etc.

Heteroaryl group: pyridyl group, pyrimidinyl group, triazinyl group, furyl group, pyrrolyl group, thienyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group, carbazolyl group, and Nocarbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalinyl group, benzoimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, naphthyridinyl group, phenanthrolinyl group, acridi Nyl group, carbolinyl group, etc.

In addition, the above-mentioned amino group, aryl group, and heteroaryl group may have a substituent. Substituents include the following groups in addition to deuterium atoms, cyano groups, nitro groups, etc.

Halogen atoms, such as fluorine atom, chlorine atom, bromine atom, iodine atom;

Alkyl groups, especially those having 1 to 8 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group , neopentyl group, n-hexyl group, isohexyl group, neohexyl group, n-heptyl group, isoheptyl group, neoheptyl group, n-octyl group, isooctyl group, neooctyl group;

Alkyloxy groups, especially those having 1 to 8 carbon atoms, such as methyloxy group, ethyloxy group, and propyloxy group;

Alkenyl group, such as vinyl group, allyl group;

Aryloxy group, such as phenyloxy group, tolyloxy group;

Aryl groups, such as phenyl group, biphenylyl group, terphenylyl group, naphthyl group, anthracenyl group, phenanthrenyl group, fluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, triphenyl group Nilgi ;

Heteroaryl groups, such as pyridyl group, pyrimidinyl group, triazinyl group, thienyl group, furyl group, pyrrolyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group, carbamate Zolyl group, indenocarbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalinyl group, benzoimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, carbolinyl group;

Arylvinyl group, such as styryl group, naphthylvinyl group;

Acyl groups, such as acetyl groups and benzoyl groups.

Moreover, these substituents may further have the substituents exemplified above.

In addition, it is preferable that these substituents exist independently, but even if these substituents are bonded to each other through a single bond, a methylene group that may have a substituent, an oxygen atom, or a sulfur atom, they form a ring. do.

For example, the above-mentioned aryl group or heteroaryl group may have a phenyl group as a substituent, and this phenyl group may further have a phenyl group as a substituent. That is, taking an aryl group as an example, this aryl group may be a biphenylyl group, terphenylyl group, or triphenylenyl group.

In the high molecular weight compound of the present invention, because it is easy to synthesize, it is preferable that X in the general formula (1) and X in the general formula (2) are the same group, and it is more preferable that all

The phenylene group represented by L in the above general formula (1) may have a substituent. The substituent includes the same groups as the substituents that X may have as described above, and these substituents may further have a substituent.

n in the general formula (1) represents the number of L. In the high molecular weight compound of the present invention, n is preferably 0 or 1 from the viewpoints of hole injection/transport performance, electron blocking ability, and thin film stability.

In the general formula (2), Y is an oxygen atom (O), a sulfur atom (S), or a group represented by the following formula (3).

R ₄ in the formula represents a substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group.

Examples of the alkyl group represented by R ₄ include the same groups as those described above. Moreover, examples of the aryl group include the same groups as the groups described above.

In the high molecular weight compound of the present invention, it is preferable that Y is an oxygen atom (O) from the viewpoints of hole injection/transport performance, electron blocking ability, and thin film stability.

In the present invention, specific examples of the repeating unit A represented by the above-mentioned general formula (1) are shown in Figures 1 to 5 as repeating units 1-1 to 1-28. In addition, specific examples of repeating unit B represented by the above-mentioned general formula (2) are shown as repeating units 2-1 to 2-68 in Figures 6 to 17. In addition, in the chemical structures shown in Figures 1 to 17, the broken lines represent bonding hands to adjacent repeating units, and the solid lines with free ends extending from the ring indicate that the free ends are methyl groups. . Although preferred specific examples of repeating units have been shown, the repeating units used in the present invention are not limited to these examples.

In addition, in the present invention, specific examples of In addition, in the chemical formulas shown in Figures 18 and 19, broken lines indicate bonding points. Although preferred specific examples of the substituent are shown, X used in the present invention is not limited to these examples.

＜High molecular weight compounds＞

The high molecular weight compound of the present invention containing repeating units represented by the above-mentioned general formula (1) and general formula (2) has properties such as hole injection characteristics, hole mobility, electron blocking ability, thin film stability, and heat resistance. From the viewpoint of further increasing and securing film forming properties, the weight average molecular weight in terms of polystyrene as measured by GPC is preferably 10,000 to less than 1,000,000, more preferably 10,000 to less than 500,000, and 10,000 to less than 300,000. It is more desirable.

In order to increase thermal crosslinkability, the high molecular weight compound of the present invention preferably contains a repeating unit having a heat crosslinkable structural unit Q represented by the following general formula (4).

During the ceremony,

R ₃ , X and a all have the same definition as shown in General Formula (1).

In the high molecular weight compound of the present invention, because it is easy to synthesize, it is preferable that R ₃ in the general formula (4) is the same group as R ₃ in the general formulas (1) and (2), and It is preferable that X in (4) is the same group as X in the above general formulas (1) and (2).

Specific examples of the heat-crosslinkable structural unit Q include structures represented by the following general formulas (5a) to (5af).

R ₁ , R ₂ , a and b in the above general formulas (5a) to (5af) all have the same definitions as those shown in general formula (1).

In addition, in the above formulas (5a) to (5af), the broken line represents a bond to an adjacent structural unit, and the solid line with a free tip extending from the ring indicates that the tip is a methyl group.

The high molecular weight compound of the present invention preferably contains 1 mol% or more, especially 30 mol% or more, of the repeating unit A. Provided that the repeating unit A is included in this amount, 1 mole of the repeating unit B % or more, especially in an amount of 10 to 60 mol%, and further, when the repeating unit represented by the general formula (4) is represented by Q, the repeating unit Q is included in an amount of 1 mol% or more, especially 10 to 20 mol%. It is preferable to include it in an amount, and it is most preferable to include repeating units A, B, and Q so as to satisfy these conditions when forming an organic layer of an organic EL device.

The high molecular weight compound of the present invention is synthesized by linking each structural unit by forming a C-C bond or a C-N bond, respectively, through the Suzuki polymerization reaction or the HARTWIG-BUCHWALD polymerization reaction. That is, the high molecular weight compound of the present invention can be synthesized by preparing a unit compound having each structural unit, boric acid esterification or halogenation of this unit compound, and polycondensation reaction using an appropriate catalyst.

For example, a high molecular weight compound containing 60 mol% of repeating unit A, 30 mol% of repeating unit B, and 10 mol% of repeating unit Q is represented by the following general formula (5).

The high molecular weight compound of the present invention is dissolved in an aromatic organic solvent such as benzene, toluene, xylene, or anisole to prepare a coating liquid, and this coating liquid is coated on a predetermined substrate and heated and dried to obtain hole injection properties. , it is possible to form a thin film with excellent properties such as hole transport and electron blocking properties. The resulting thin film has good heat resistance and, furthermore, good adhesion to other layers.

The high molecular weight compound of the present invention can be used as a constituent material of the hole injection layer and/or hole transport layer of an organic EL device. Compared to those formed from conventional materials, the hole injection layer and hole transport layer formed from the high molecular weight compound of the present invention have high hole injection properties, high mobility, high electron blocking properties, and are capable of preventing exciton generated in the light-emitting layer. The advantage of being able to confine and improve the recombination probability of holes and electrons is that high luminous efficiency can be obtained, and the driving voltage is lowered and the durability of the organic EL device is improved can be realized.

In addition, the high molecular weight compound of the present invention having the above-described electrical properties has a wider gap than conventional materials and is effective in confining excitons, so it can naturally be suitably used in an electron blocking layer or a light-emitting layer.

＜Organic EL device＞

The organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention described above has a structure shown in Fig. 20, for example. That is, on the glass substrate 1 (may be another transparent substrate such as a transparent resin substrate), a transparent anode 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, and a light emitting layer 6 ), an electron transport layer (7) and a cathode (8) are formed.

Of course, the organic EL device to which the high molecular weight compound of the present invention is applied is not limited to the above layer structure, and a hole blocking layer can be formed between the light-emitting layer 6 and the electron transport layer 7, and further, An electron injection layer may be formed between the cathode (8) and the electron transport layer (7). You can also omit some layers. For example, a simple layer structure may be used in which an anode 2, a hole transport layer 4, a light emitting layer 6, an electron transport layer 7, and a cathode 8 are formed on the substrate 1. Additionally, a two-layer structure can be used in which layers with the same function are overlapped.

The high molecular weight compound of the present invention takes advantage of its hole injection properties and hole transport properties, and is used to form an organic layer (e.g., hole injection layer 3, hole injection layer 3) formed between the anode 2 and the cathode 8. It is preferably used as a forming material for the transport layer (4), the electron blocking layer (5), or the light-emitting layer (6).

In the above organic EL device, the transparent anode 2 is formed of a known electrode material, and an electrode material with a large work function such as ITO or gold is used as the substrate 1 (a transparent substrate such as a glass substrate). ) is formed by depositing on.

In addition, the hole injection layer 3 formed on the transparent anode 2 is a coating solution obtained by dissolving the high molecular weight compound of the present invention in an aromatic organic solvent such as toluene, xylene, or anisole. It can be formed using That is, the hole injection layer 3 can be formed by coating this coating liquid on the transparent anode 2 by spin coating, inkjet, etc.

In addition, in the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the hole injection layer 3 does not use the high molecular weight compound of the present invention, but is made of a conventionally known material, such as For example, it can also be formed using the following materials.

Porphyrin compounds represented by copper phthalocyanine;

Star burst type triphenylamine derivative;

Arylamines having a bivalently linked structure containing no single bonds or heteroatoms (for example, triphenylamine trimers and tetramers);

Acceptor heterocyclic compounds such as hexacyanoazatriphenylene;

Coated polymer materials, such as poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrenesulfonate) (PSS), etc.

A layer (thin film) using such a material can be formed by deposition, coating using a spin coating method, an inkjet method, etc. These are the same for other layers, and depending on the type of film-forming material, film formation is performed by a vapor deposition method or a coating method.

Like the hole injection layer 3, the hole transport layer 4 formed on the hole injection layer 3 can be formed by spin coating or inkjet coating using the high molecular weight compound of the present invention.

Moreover, in the organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention, the hole transport layer 4 can also be formed using a conventionally known hole transport material. Representative examples of such hole transport materials are as follows.

Benzidine derivatives, such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter abbreviated as TPD); N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (hereinafter abbreviated as NPD); N,N,N',N'-Tetrabiphenylylbenzidine.

Amine-based derivatives, such as 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC).

Various triphenylamine trimers and tetramers.

A coated polymer material also used as a hole injection layer.

The compounds of the hole transport layer described above, including the high molecular weight compound of the present invention, may be formed into a film individually, or two or more types may be mixed together to form a film. In addition, one or more types of the above compounds may be used to form multiple layers, and the multilayer film in which such layers are laminated may be used as a hole transport layer.

Additionally, in the organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention shown in FIG. 20, a layer that also serves as the hole injection layer 3 and the hole transport layer 4 may be used, and such holes The injection/transport layer can be formed by coating using a polymer material such as PEDOT.

Additionally, in the hole transport layer 4 (the same applies to the hole injection layer 3), materials commonly used in that layer include trisbromophenylaminehexachlorantimony or radialene derivatives (e.g., WO2014/009310 (Reference) etc. doped with P can be used. Additionally, the hole transport layer 4 (or hole injection layer 3) can be formed using a polymer compound having a TPD basic skeleton or the like.

In addition, as shown in FIG. 20, an electron blocking layer can be formed between the hole transport layer and the light emitting layer, and can be formed, for example, by coating by spin coating or inkjet using the high molecular weight compound of the present invention. there is.

In addition, in the organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention, a known electron blocking compound having an electron blocking function, for example, a carbazole derivative, or a triphenylsilyl group and The electron blocking layer can also be formed using a compound having a triarylamine structure. Representative examples are as follows.

Carbazole derivatives, such as 4,4',4''-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated as TCTA); 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene; 1,3-bis(carbazol-9-yl)benzene (hereinafter abbreviated as mCP); 2,2-bis(4-carbazol-9-ylphenyl)adamantane (hereinafter abbreviated as Ad-Cz).

Compounds with a triarylamine structure, such as 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

The electron blocking layer may also be formed individually, including the high molecular weight compound of the present invention, or may be formed by mixing two or more types. In addition, one or more types of the above compounds may be used to form multiple layers, and the multilayer film in which such layers are laminated may be used as an electron blocking layer.

In the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the light-emitting layer 6 is a metal complex of quinolinol derivatives including Alq ₃ , as well as various metal complexes such as zinc, beryllium, and aluminum. , anthracene derivatives, bistyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, and polyparaphenylenevinylene derivatives.

Additionally, the light-emitting layer 6 may be composed of a host material and a dopant material. As a host material in this case, in addition to the above-mentioned light-emitting materials, thiazole derivatives, benzimidazole derivatives, polydialkyl fluorene derivatives, etc. can be used, and the high molecular weight compound of the present invention described above can also be used. As dopant materials, quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, aminostyryl derivatives, etc. can be used.

Such a light-emitting layer 6 may also have a single-layer structure using one or two or more types of each light-emitting material, or may have a multi-layer structure in which a plurality of layers are stacked.

Additionally, the light-emitting layer 6 can also be formed using a phosphorescent material as the light-emitting material. As the phosphorescent material, a phosphorescent material made of a metal complex such as iridium or platinum can be used. For example, a green phosphorescent emitter such as Ir(ppy) ₃ , a blue phosphorescent emitter such as FIrpic or FIr6, a red phosphorescent emitter such as Btp ₂ Ir(acac), etc. can be used. These phosphorescent materials include: It is used by doping a hole injection/transport host material or an electron transport host material.

In addition, in order to avoid concentration quenching, it is preferable to dope the host material of the phosphorescent light-emitting material by co-deposition in the range of 1 to 30 weight percent with respect to the entire light-emitting layer.

Additionally, as a light-emitting material, materials that emit delayed fluorescence such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN can be used (Appl. Phys. Let., 98, 083302 (2011), Chem. Comu ㎜., 48, 11392 (2012), NatuRe, 492, 234 (2012)).

By supporting the high molecular weight compound of the present invention with a fluorescent emitter, a phosphorescent emitter, or a material that emits delayed fluorescence, called a dopant, to form the light emitting layer (6), an organic EL device with reduced driving voltage and improved luminous efficiency is provided. It can be realized.

In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the high molecular weight compound of the present invention can be used as a host material for hole injection and transport. In addition, carbazole derivatives such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP can also be used.

In addition, in the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, p-bis(triphenylsilyl)benzene (hereinafter abbreviated as UGH2) and 2,2 as the electron transporting host material. ',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI), etc. can be used.

In the organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention, the hole blocking layer (not shown in Fig. 20) formed between the light-emitting layer 6 and the electron transport layer 7 is itself It can be formed using a known compound having a hole blocking effect. Examples of known compounds having such a hole blocking effect include the following.

Phenanthroline derivatives such as basocuproine (hereinafter abbreviated as BCP);

Metal complexes of quinolinol derivatives such as aluminum(III)bis(2-methyl-8-quinolinate)-4-phenylphenolate (hereinafter abbreviated as BAlq);

Various rare earth complexes;

triazole derivatives;

Triazine derivatives;

Oxadiazole derivatives.

These materials can also be used to form the electron transport layer 7 described below, and can also be used as a hole blocking layer and electron transport layer 7.

Such a hole blocking layer can also have a single-layer or multi-layer laminated structure, and each layer is formed into a film using one type or two or more types of the compounds having the hole blocking effect described above.

In the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the electron transport layer 7 is an electron transport compound known per se, for example, quinolinol including Alq ₃ and BAlq. In addition to metal complexes of derivatives, various metal complexes, pyridine derivatives, pyrimidine derivatives, triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silol It is formed using derivatives, benzimidazole derivatives, etc.

This electron transport layer 7 can also have a single-layer or multi-layer laminated structure, and each layer is formed into a film using one or two or more of the electron transport compounds described above.

In addition, in the organic EL device provided with an organic layer formed using the high molecular weight compound of the present invention, the electron injection layer (not shown in Fig. 20) formed as needed is also known per se, for example , alkali metal salts such as lithium fluoride and cesium fluoride, alkaline earth metal salts such as magnesium fluoride, metal oxides such as aluminum oxide, and organic metal complexes such as lithium quinoline.

As the cathode 8 of the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, an electrode material with a low work function such as aluminum, and an electrode material such as magnesium silver alloy, magnesium indium alloy, and aluminum magnesium alloy are used. , alloys with lower work functions are used as electrode materials.

As described above, by forming at least one of the hole injection layer, hole transport layer, electron blocking layer, and light emitting layer using the high molecular weight compound of the present invention, luminous efficiency and power efficiency are high, and the practical driving voltage is low. An organic EL device with a low emission start voltage and extremely excellent durability is obtained. In particular, this organic EL device has high luminous efficiency, while driving voltage is lowered, current tolerance is improved, and maximum luminance is improved.

Example

Hereinafter, the present invention will be explained by the following experimental examples.

In addition, in the following description, the repeating unit represented by the general formula (1) of the high molecular weight compound of the present invention is referred to as "repeating unit A", the repeating unit represented by general formula (2) is referred to as "repeating unit B", and heat crosslinkability The repeating unit represented by general formula (4) having the structural unit Q is indicated as “repeating unit Q”.

In addition, the synthesized compound was purified by column chromatography and crystallization using a solvent. Identification of the compound was performed by NMR analysis.

In order to produce the high molecular weight compound of the present invention, the following intermediates 1 to 3 were synthesized.

＜Synthesis of Intermediate 1＞

Intermediate 1 is used to introduce the partial structure of repeating unit 1-1 shown in FIG. 1.

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was ventilated for 30 minutes.

N,N-bis(4-bromophenyl)-9,9-di-n-octyl-9H-fluoren-2-amine: 16.7 g

Bis(Pinacolato)diborone: 11.9 g

Potassium acetate: 5.7 g

1,4-dioxane: 170 ml

Next, 0.19 g of a dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, heated, and stirred at 100°C for 7 hours. After cooling to room temperature, water and toluene were added and a liquid separation operation was performed to collect the organic layer. This organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (ethyl acetate/n-hexane = 1/20) to obtain 7.6 g (yield 40%) of the white powder of Intermediate 1.

＜Synthesis of Intermediate 2＞

Intermediate 2 is used to introduce a structural unit represented by general formula (5e), which is a thermally crosslinkable structural unit Q.

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was ventilated for 30 minutes.

N,N-bis(4-bromophenyl)-N-(benzocyclobuten-4-yl)-amine: 8.0 g

Bis(Pinacolato)diborone: 9.9 g

Potassium acetate: 4.6 g

1,4-dioxane: 80 ml

Next, 0.3 g of a dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, heated, and stirred at 90°C for 11 hours. After cooling to room temperature, city water and toluene were added, and the organic layer was collected by performing a liquid separation operation. This organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product. The crude product was recrystallized using toluene/methanol = 1/2 to obtain 3.4 g of white powder of Intermediate 2 (yield 35%).

＜Synthesis of Intermediate 3＞

Intermediate 3 is used to introduce the partial structure of repeating unit 2-1 shown in Figure 6.

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was ventilated for 30 minutes.

Bis(p-bromophenyl)-2-dibenzofuranamine: 32.0 g

Bis(Pinacolato)diborone: 34.6 g

Potassium acetate: 19.1 g

1,4-dioxane: 150 ml

Next, 0.5 g of a dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, heated, and stirred at 100°C for 13 hours. After cooling to room temperature, city water and chloroform were added, and the organic layer was collected by performing a liquid separation operation. This organic layer was dehydrated with anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude product. By recrystallizing the crude product using toluene/methanol = 1/1, 18.6 g (48% yield) of almost white powder of Intermediate 3 was obtained.

<Example 1>

Synthesis of high molecular weight compound I;

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was ventilated for 30 minutes.

Intermediate 1: 3.6 g

Intermediate 2: 0.4 g

Intermediate 3: 1.3 g

1,3-dibromobenzene: 1.7 g

Tripotassium phosphate: 7.4 g

Toluene: 9 ml

Water: 5 ml

1,4-dioxane: 27 ml

Next, 1.5 mg of palladium (II) acetate and 12.3 mg of tri-o-tolylphosphine were added, heated, and stirred at 88°C for 8 hours. After that, 19 mg of phenylboronic acid was added and stirred for 1 hour, and then 261 mg of bromobenzene was added and stirred for 1 hour. 50 ml of toluene and 50 ml of a 5 wt% aqueous solution of sodium N,N-diethyldithiocarbamidate were added, heated, and stirred under reflux for 2 hours. After cooling to room temperature, the organic layer was collected by carrying out a liquid separation operation and washed three times with saturated saline solution. The organic layer was dehydrated with anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude polymer. The crude polymer was dissolved in toluene, silica gel was added, adsorption purification was performed, and silica gel was removed by filtration. The obtained filtrate was concentrated under reduced pressure, 100 ml of toluene was added to the dried product to dissolve it, and the solution was added dropwise to 300 ml of n-hexane, and the resulting precipitate was collected by filtration. This operation was repeated four times and dried to obtain 3.2 g (76% yield) of high molecular weight compound I.

The average molecular weight and dispersion degree of high molecular weight compound I measured by GPC were as follows.

Number average molecular weight Mn (polystyrene equivalent): 64,000

Weight average molecular weight Mw (polystyrene equivalent): 141,000

Dispersion (Mw/Mn): 2.2

In addition, NMR measurement was performed on high molecular weight Compound I. From the ¹ H-NMR measurement results shown in Figure 21, the chemical composition of high molecular weight compound I was as follows.

From the above chemical composition, it can be seen that the polymer compound I contains 60 mol% of the repeating unit A, 30 mol% of the repeating unit B, and 10 mol% of the repeating unit Q. In addition, the molar ratio of each structural unit is an estimated value obtained from ¹ H-NMR measurement results.

<Example 2>

Using the high molecular weight compound I synthesized in Example 1, a coating film with a film thickness of 80 nm was produced on an ITO substrate, and the work function was measured with an ionization potential measurement device (Type PYS-202, manufactured by Sumitomo Heavy Industries, Ltd.) . The work function of high molecular weight compound I was 5.62 eV.

It can be seen that high molecular weight compound I exhibits a preferable energy level compared to the work function of 5.4 eV of common hole transport materials such as NPD and TPD, and has good hole transport ability and hole injection properties.

<Example 3>

Using the high molecular weight compound I synthesized in Example 1, a vapor-deposited film with a film thickness of 50 nm was produced on a quartz substrate, the ultraviolet-visible absorption spectrum was measured with a commercially available spectrophotometer, and the band gap was determined from the wavelength of the absorption edge on the long wavelength side. was calculated. Additionally, electron affinity was calculated from the work function and band gap values. The band gap of high molecular weight compound I was 3.14 eV, and the calculated electron affinity was 2.48 eV.

In addition, the band gap of NPD, a common hole transport material, is 3.00 eV and the electron affinity is 2.40 eV.

It can be seen that the high molecular weight compound I has a wide gap compared to NPD, shows a preferable energy level even when comparing electron affinity, and has a good electron blocking ability.

<Example 4>

An organic EL device having a layered structure shown in FIG. 20 was produced by the following method.

Specifically, the glass substrate 1 on which ITO with a film thickness of 50 nm was formed was washed with an organic solvent, and then the ITO surface was cleaned by UV/ozone treatment. To cover the transparent anode 2 (ITO) formed on the glass substrate 1, PEDOT/PSS (manufactured by Ossila) was formed into a film with a thickness of 50 nm by spin coating, and placed on a hot plate at 200°C for 10 days. It was dried for a minute to form a hole injection layer (3).

A coating liquid was prepared by dissolving 0.4 wt% of a high molecular weight compound (HTM-1) with the following structural formula in toluene. The substrate on which the hole injection layer 3 was formed as described above was transferred into a glove box purged with dry nitrogen, dried on a hot plate at 230° C. for 10 minutes, and then the above-described coating was applied onto the hole injection layer 3. Using the liquid, a 15 nm thick coating layer was formed by spin coating, and then dried on a hot plate at 220°C for 30 minutes to form the hole transport layer 4.

A coating liquid was prepared by dissolving 0.4 wt% of high molecular weight compound I obtained in Example 1 in toluene. On the hole transport layer 4 formed as described above, a coating layer with a thickness of 15 nm was formed by spin coating using the coating liquid described above, and dried on a hot plate at 220° C. for 30 minutes to form an electron blocking layer ( 5) was formed.

The substrate on which the electron blocking layer 5 was formed as described above was placed in a vacuum evaporator and the pressure was reduced to 0.001 Pa or less. On the electron blocking layer 5, a light emitting layer 6 with a film thickness of 34 nm was formed by binary vapor deposition of a blue light emitting material (EMD-1) and a host material (EMH-1). In addition, in binary deposition, the deposition rate ratio was set to EMD-1:EMH-1 = 4:96.

On the light-emitting layer 6 formed above, an electron transport layer 7 with a film thickness of 20 nm was formed by binary vapor deposition using electron transport materials (ETM-1) and (ETM-2). In addition, in binary deposition, the deposition rate ratio was set to ETM-1:ETM-2 = 50:50.

Finally, aluminum was deposited to a film thickness of 100 nm to form the cathode 8.

In this way, the glass substrate on which the transparent anode (2), hole injection layer (3), hole transport layer (4), electron blocking layer (5), light emitting layer (6), electron transport layer (7) and cathode (8) is formed. was moved into a glove box replaced with dry nitrogen, and another glass substrate for sealing was bonded using UV curing resin to form an organic EL device. For the produced organic EL device, characteristics were measured in the air and at room temperature. Additionally, the light emission characteristics were measured when a direct current voltage was applied to the manufactured organic EL device. The above measurement results are shown in Table 1.

<Comparative Example 1>

An organic EL device was manufactured in exactly the same manner as in Example 4, except that instead of the high molecular weight compound I, the electron blocking layer 5 was formed using a coating solution prepared by dissolving 0.4 wt% of TFB (hole transport polymer) in toluene. was produced.

TFB (hole transport polymer) is poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenyl amine] (Hole Transport Polymer ADS259BE, manufactured by American Dye Source.) Regarding the organic EL device of Comparative Example 1, various characteristics were evaluated in the same manner as Example 4, and the results are shown in Table 1.

In the evaluation of various characteristics, voltage, luminance, luminous efficiency, and power efficiency are values when a current with a current density of 10 mA/cm2 is passed. In addition, the device life is as follows: When constant current driving is performed with the emission luminance (initial luminance) at the start of light emission being 700 cd/m2, the emission luminance is 560 cd/m2 (80% when the initial luminance is 100%). It was measured as the time until attenuation (equivalent: 80% attenuation).

As shown in Table 1, the luminous efficiency when a current with a current density of 10 mA/cm2 is passed is 7.52 cd/A for the organic EL device of Example 4, compared to 5.50 cd/A for the organic EL device of Comparative Example 1. It was highly efficient. Additionally, in terms of device life (80% attenuation), the organic EL device of Example 4 had a longer life of 136 hours compared to 11 hours for the organic EL device of Comparative Example 1.

The high molecular weight compound of the present invention has a high hole transport ability and an excellent electron blocking ability, and is therefore excellent as a compound for application-type organic EL devices. By producing a coating-type organic EL device using the compound, high luminous efficiency and power efficiency can be obtained, and durability can be improved. For example, it has become possible to deploy it in home telephone products and lighting applications.

1: Glass substrate
2: Transparent anode
3: hole injection layer
4: hole transport layer
5: Electronic blocking layer
6: light emitting layer
7: electron transport layer
8: cathode

Claims (11)

A high molecular weight compound comprising a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and having a weight average molecular weight of 10,000 or more and less than 1,000,000 in terms of polystyrene.


During the ceremony,
R ₁ and R ₃ are each independently a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a halogen atom, or an alkyl group, an alkyloxy group, a cycloalkyl group, a cycloalkyloxy group, an alkenyl group, or an alkyl group having 40 or less carbon atoms. Represents an aryloxy group.
a, b and c are the following integers.
a = 0, 1, 2 or 3
b = 0, 1, 2, 3 or 4
c = 0 or 1
R ₂ each independently represents an alkyl group, an alkyloxy group, or a cycloalkyl group having 3 to 40 carbon atoms.
L represents a phenylene group, and n represents an integer of 0 to 3.
X each independently represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group.
Y is an oxygen atom (O), a sulfur atom (S), or a group represented by the following formula (3).

R ₄ in the formula represents a substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group. According to claim 1,
A high molecular weight compound in the general formulas (1) and (2) above, wherein R ₁ and R ₃ are hydrogen atoms. The method of claim 1 or 2,
A high molecular weight compound in the general formula (1) above, wherein R ₂ is an alkyl group having 3 to 40 carbon atoms. The method of claim 1 or 2,
In the above general formulas (1) and (2), A high molecular weight compound that is a bazolyl group or an acridinyl group. The method of claim 1 or 2,
A high molecular weight compound containing a repeating unit having a thermally crosslinkable structural unit Q, represented by the following general formula (4).

During the ceremony,
R ₃ , X and a all have the same definition as shown in General Formula (1). According to claim 5,
A high molecular weight compound in the general formula (4) above, wherein the thermally crosslinkable structural unit Q is a structure represented by the following general formulas (5a) to (5af).


During the ceremony,
R ₁ , R ₂ , a and b all have the same definition as shown in General Formula (1). An organic electroluminescence device having a pair of electrodes and an organic layer sandwiched between them, wherein the organic layer uses the high molecular weight compound according to claim 1 or 2 as a constituent material. device. According to claim 7,
An organic electroluminescence device wherein the organic layer is a hole transport layer. According to claim 7,
An organic electroluminescence device, wherein the organic layer is an electron blocking layer. According to claim 7,
An organic electroluminescence device wherein the organic layer is a hole injection layer. According to claim 7,
An organic electroluminescence device wherein the organic layer is a light-emitting layer.