JP2024008856A - High molecular weight compound and organic electroluminescent device using these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer material excellent in injection/transportation performance of a positive hole, having electron stopping capability, and high in the stability in a thin film state, and an organic EL device having an organic layer (thin film) formed from the polymer material, high in emission efficiency, and having a long life time.

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 its molecular main chain. Preferably, the high molecular weight compound includes a thermally crosslinkable structural unit in a molecular main chain.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

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

Since organic EL elements are self-luminous elements, they are brighter, have better visibility than liquid crystal elements, and are capable of providing clearer display, and have therefore been actively researched.

An organic EL element has 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 classified into vacuum evaporation methods and coating methods. The vacuum evaporation method is a method of forming a thin film on a substrate in vacuum, mainly using a low-molecular compound, and is a technology that has already been put into practical use. On the other hand, the coating method is a method that mainly uses polymeric compounds to form a thin film on a substrate using a solution such as inkjet or printing.It has high material usage efficiency and is suitable for large areas and high definition. This technology will be essential for future large-area organic EL displays.

Vacuum deposition methods using low-molecular materials have extremely low material usage efficiency, and as the size increases, the shadow mask becomes more deflected, making uniform deposition on large substrates difficult. It also has the problem of high manufacturing costs.

On the other hand, with polymeric materials, it is possible to form a uniform film even on large substrates by applying a solution dissolved in an organic solvent. A coating method can be used. Therefore, it becomes possible to increase the efficiency of material usage, and it is possible to significantly reduce the manufacturing cost required for producing the device.

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

Furthermore, a fluorene polymer called TFB has been known as a typical hole transport material in organic EL devices using polymer materials (see Patent Documents 6 to 7). However, since TFB has insufficient hole transporting properties and insufficient electron blocking properties, there is a problem in that some electrons pass through the light emitting layer, making it impossible to expect improvement in luminous efficiency. Furthermore, since the film adhesion with adjacent layers is low, there is a problem in that it cannot be expected to extend the life of the device.

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

An object 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. Furthermore, it is an object of the present invention to provide an organic EL element that has an organic layer (thin film) formed of the polymeric material, has high luminous efficiency, and has a long life.

The present inventors focused on the fact that high molecular weight compounds containing a triarylamine structural unit with a fluorene ring in the molecular main chain have high hole injection and transport ability, and are also expected to have a wide gap. As a result of synthesizing and studying a high molecular weight compound containing a lylamine structural unit, the present invention was completed.

That is, the present invention is as described below.

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

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, or a cycloalkyloxy group having 40 or less carbon atoms. group, alkenyl group, or 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.
Each X 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 general formulas (1) and (2), X is a diphenylamino group, a phenyl group, a naphthyl group, a dibenzofuranyl group, a dibenzothienyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, an indenocarbazolyl group. The high molecular weight compound according to [1] or [2], which is a group or an acridinyl group.

[5] The high molecular weight compound according to [1] or [2], which contains 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 thermally crosslinkable structural unit Q has a structure shown in 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 definition as shown in general formula (1).

[7] An organic electroluminescent 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. Electroluminescent element.

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

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

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

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

The above-mentioned high molecular weight compound of the present invention is
(1) Good hole injection characteristics
(2) High hole mobility
(3) Wide gap and excellent electron blocking ability.
It has the following characteristics.

An 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 includes:
(1) High luminous efficiency and power efficiency;
(2) Practical driving voltage is low.
(3) Has a long lifespan;
It has the advantage of

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

Chemical structure of repeating units 1-1 to 1-6 suitable as repeating unit A represented by general formula (1) of the present invention Chemical structure of repeating units 1-7 to 1-12 suitable as repeating unit A represented by general formula (1) of the present invention Chemical structure of repeating units 1-13 to 1-18 suitable as repeating unit A represented by general formula (1) of the present invention Chemical structure of repeating units 1-19 to 1-24 suitable as repeating unit A represented by general formula (1) of the present invention Chemical structure of repeating units 1-25 to 1-28 suitable as repeating unit A represented by general formula (1) of the present invention Chemical structure of repeating units 2-1 to 2-6 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-7 to 2-12 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-13 to 2-18 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-19 to 2-24 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-25 to 2-30 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-31 to 2-36 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-37 to 2-42 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-43 to 2-48 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-49 to 2-54 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-55 to 2-60 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-61 to 2-66 suitable as repeating unit B represented by general formula (2) of the present invention Chemical structure of repeating units 2-67 to 2-68 suitable as repeating unit B represented by general formula (2) of the present invention In the present invention, chemical structures of substituents 1 to 24 suitable as X in general formula (1), general formula (2) and general formula (4) In the present invention, chemical structures of substituents 25 to 48 suitable as X in general formula (1), general formula (2) and general formula (4) Example of layer structure of organic EL element of the present invention ^1H -NMR chart of high molecular weight compound I of Example 1

<Repeat unit A and repeat 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, or a cycloalkyloxy group having 40 or less carbon atoms. group, alkenyl group, or 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.
Each X 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.

Examples of the halogen atom represented by R ₁ and R ₃ in the general formulas (1) and (2) include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.
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 above, each have 1 carbon number. -8 alkyl group, C1-8 alkyloxy group, C5-10 cycloalkyl group, C5-10 cycloalkyloxy group, C2-6 alkenyl group, and C6 ~10 aryloxy groups are preferred.

Examples of the alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, and aryloxy group include the following groups.
Alkyl group (1 to 8 carbon atoms); 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, etc.
Alkyloxy group (1 to 8 carbon atoms); 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 (having 5 to 10 carbon atoms); cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, etc.
Cycloalkyloxy group (having 5 to 10 carbon atoms); cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group, 1-adamantyloxy group, 2-adamantyloxy group, etc.
Alkenyl group (having 2 to 6 carbon atoms); vinyl group, allyl group, isopropenyl group, 2-butenyl group, etc.
Aryloxy group (having 6 to 10 carbon atoms); phenyloxy group, tolyloxy group, etc.

In the high molecular weight compound of the present invention, R ₃ in the general formula (1) and R ₃ in the general formula (2) are preferably the same group because synthesis is easy.
Further, it is preferable that R ₁ and R ₃ in the general formulas (1) and (2) are all 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 mentioned above.

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

As the monovalent aryl group and monovalent heteroaryl group represented by X in the general formulas (1) and (2), the following groups can be exemplified.
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, indenocarbazolyl group, benzoxane Zolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, naphthyridinyl group, phenanthrolinyl group, acridinyl group, carbolinyl group, etc.

Moreover, the above-mentioned amino group, aryl group and heteroaryl group may have a substituent. Examples of the substituent include a deuterium atom, a cyano group, a nitro group, and the following groups.
Halogen atoms, such as fluorine atoms, chlorine atoms, bromine atoms, iodine atoms;
Alkyl groups, especially those having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 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 with 1 to 8 carbon atoms, such as methyloxy, ethyloxy, propyloxy groups;
Alkenyl groups, such as vinyl groups, allyl groups;
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, triphenylenyl group;
Heteroaryl groups, such as pyridyl groups, pyrimidinyl groups, triazinyl groups, thienyl groups, furyl groups, pyrrolyl groups, quinolyl groups, isoquinolyl groups, benzofuranyl groups, benzothienyl groups, indolyl groups, carbazolyl groups, indenocarbazolyl groups, Benzoxazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, carbolinyl group;
Aryl vinyl groups, such as styryl groups, naphthyl vinyl groups;
Acyl groups, such as acetyl and benzoyl groups.

Moreover, these substituents may further have the substituents exemplified above.
Furthermore, it is preferable that these substituents exist independently, but if these substituents exist through a single bond, a methylene group that may have a substituent, an oxygen atom, or a sulfur atom, may be bonded to each other to form a ring.

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, a terphenylyl group, or a triphenylenyl group.

In the high molecular weight compound of the present invention, since synthesis is easy, it is preferable that X in the general formula (1) and X in the general formula (2) are the same group, and all Xs are hydrogen atoms. It is more preferable that

The phenylene group represented by L in the general formula (1) may have a substituent. Examples of the substituent include the same substituents as the above-mentioned substituents that X may have, 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 viewpoint 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 mentioned above. Furthermore, examples of the aryl group include the same groups as those mentioned above.

In the high molecular weight compound of the present invention, Y is preferably 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 FIGS. 1 to 5 as repeating units 1-1 to 1-28. Further, specific examples of the repeating unit B represented by the above-mentioned general formula (2) are shown as repeating units 2-1 to 2-68 in FIGS. 6 to 17. In the chemical structures shown in FIGS. 1 to 17, the broken lines indicate bonds to adjacent repeating units, and the solid lines with free tips extending from the ring indicate that the free tips are methyl groups. It is shown that. Although preferred specific examples of repeating units are shown, the repeating units used in the present invention are not limited to these examples.

Further, in the present invention, specific examples of X in the above-mentioned general formulas (1), general formulas (2) and general formulas (4) are shown as substituents 1 to 48 in FIGS. 18 and 19. In the chemical formulas shown in FIGS. 18 and 19, the wavy lines indicate bonding locations. Although preferable specific examples of the substituents are shown, X used in the present invention is not limited to these examples.

<High molecular weight compound>
The high molecular weight compound of the present invention containing repeating units represented by the general formulas (1) and (2) described above has good hole injection properties, hole mobility, electron blocking ability, thin film stability, and heat resistance. From the viewpoint of further enhancing properties such as properties and ensuring film formability, it is preferable that the weight average molecular weight in terms of polystyrene measured by GPC is 10,000 or more and less than 1,000,000, and 10,000 or more. It is more preferably less than 500,000, and even more preferably in the range of 10,000 or more and less than 300,000.

The high molecular weight compound of the present invention preferably contains a repeating unit having a thermally crosslinkable structural unit Q represented by the following general formula (4) in order to improve thermally crosslinkable properties.

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, R ₃ in the general formula (4) is preferably the same group as R ₃ in the general formulas (1) and (2) because synthesis is easy. , X in the general formula (4) is preferably the same group as X in the general formulas (1) and (2).

Specific examples of the thermally crosslinkable structural unit Q include structures shown in 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 definition as shown in general formula (1).

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

The high molecular weight compound of the present invention preferably contains repeating unit A in an amount of 1 mol% or more, particularly 30 mol% or more. 1 mol% or more, especially 10 to 60 mol%, and furthermore, when the repeating unit represented by general formula (4) is represented by Q, the repeating unit Q is 1 mol% or more, especially 10 to 20 It is preferable that the repeating units A, B, and Q are contained in an amount of mol %, and it is most suitable for forming an organic layer of an organic EL element to contain repeating units A, B, and Q so as to satisfy such conditions.

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, by a Suzuki polymerization reaction or a HARTWIG-BUCHWALD polymerization reaction. That is, the high molecular weight compound of the present invention is synthesized by preparing a unit compound having each structural unit, appropriately boric acid esterifying or halogenating the unit compound, and performing a polycondensation reaction using an appropriate catalyst. Can be done.

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 can be prepared by dissolving it in an aromatic organic solvent such as benzene, toluene, xylene, anisole, etc. to prepare a coating solution, coating the coating solution on a predetermined base material, and heating and drying it. , it is possible to form a thin film with excellent properties such as hole injection properties, hole transport properties, and electron blocking properties. The resulting thin film has good heat resistance and also good adhesion to other layers.

The high molecular weight compound of the present invention can be used as a constituent material of a hole injection layer and/or a hole transport layer of an organic EL device. The hole injection layer and hole transport layer formed using the high molecular weight compound of the present invention have higher hole injection properties, higher mobility, and electron blocking properties compared to those formed using conventional materials. It is possible to confine excitons generated in the light-emitting layer, and to improve the probability of holes and electrons recombining, resulting in high luminous efficiency and lower driving voltage. It is possible to realize the advantage that the durability of the element is improved.

Furthermore, the high molecular weight compound of the present invention having the electrical properties described above has a wider gap than conventional materials and is effective in confining excitons, so it is naturally suitable for use in electron blocking layers and light emitting layers. can do.

<Organic EL element>
An organic EL element including 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 a glass substrate 1 (which 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, a light emitting layer 6, An electron transport layer 7 and a cathode 8 are provided.

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 provided between the light emitting layer 6 and the electron transport layer 7. Furthermore, an electron injection layer may be provided between the cathode 8 and the electron transport layer 7. Furthermore, some layers can also be omitted. For example, a simple layered structure 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 provided on the substrate 1 may be used. It is also possible to have a two-layer structure in which layers having the same function are stacked.

The high molecular weight compound of the present invention takes advantage of its properties such as hole injection and hole transport properties to provide an organic layer (for example, hole injection layer 3, positive It is suitably used as a material for forming the hole transport layer 4, electron blocking layer 5 or light emitting layer 6).

In the organic EL element described above, the transparent anode 2 may be formed of a known electrode material, and an electrode material with a high work function such as ITO or gold is formed on the substrate 1 (a transparent substrate such as a glass substrate). It is formed by vapor deposition.

Further, the hole injection layer 3 provided on the transparent anode 2 is formed using a coating liquid in which the high molecular weight compound of the present invention is dissolved in an aromatic organic solvent such as toluene, xylene, or anisole. be able to. That is, the hole injection layer 3 can be formed by coating the transparent anode 2 with this coating liquid by spin coating, inkjet, or the like.

In addition, in an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the hole injection layer 3 may be made of a conventionally known material, such as the following, without using the high molecular weight compound of the present invention. It can also be formed using the following materials.
Porphyrin compounds represented by copper phthalocyanine;
Starburst type triphenylamine derivative;
Arylamines having a structure connected by a single bond or a divalent group containing no heteroatoms (e.g., triphenylamine trimers and tetramers);
Acceptor heterocyclic compounds such as hexacyanoazatriphenylene;
Coating type polymeric materials, such as poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrene sulfonate) (PSS), etc.

A layer (thin film) using such a material can be formed by coating using a vapor deposition method, a spin coating method, an inkjet method, or the like. The same applies to other layers, and the film is formed by a vapor deposition method or a coating method depending on the type of film-forming material.

Similarly to the hole injection layer 3, the hole transport layer 4 provided on the hole injection layer 3 may also be formed by spin coating, inkjet coating, etc. using the high molecular weight compound of the present invention. Can be done.

Further, in an organic EL element including 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. Typical 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 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 that is also used as a hole injection layer.

The above-mentioned compounds for the hole transport layer, including the high molecular weight compound of the present invention, may be formed into a film alone, or two or more thereof may be mixed and formed into a film. Moreover, a plurality of layers can be formed using one or more of the above compounds, and a multilayer film in which such layers are laminated can be used as a hole transport layer.

Further, in the organic EL element shown in FIG. 20 having an organic layer formed using the high molecular weight compound of the present invention, the layer can also serve as both the hole injection layer 3 and the hole transport layer 4. Such a hole injection/transport layer can be formed by coating using a polymeric material such as PEDOT.

In addition, in the hole transport layer 4 (same as the hole injection layer 3), trisbromophenylamine hexachloroantimony or a radialene derivative (for example, see WO2014/009310) is added to the material normally used for this layer. Doped materials can be used. Further, the hole transport layer 4 (or hole injection layer 3) can be formed using a polymer compound having a TPD basic skeleton.

Furthermore, as shown in FIG. 20, an electron blocking layer can be provided between the hole transport layer and the light emitting layer, and can be formed by coating with the high molecular weight compound of the present invention by spin coating, inkjet, etc. can do.

Further, in an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, a known electron blocking compound having an electron blocking effect, such as a carbazole derivative or a triphenylsilyl group, and The electron blocking layer can also be formed using a compound having a triarylamine structure. Representative ones 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).
A compound having a triarylamine structure, for example, 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

The electron blocking layer may also be formed using a single layer containing the high molecular weight compound of the present invention, or may be formed by mixing two or more of them. Alternatively, a plurality of layers may be formed using one or more of the above compounds, and a multilayer film in which such layers are laminated can be used as an electron blocking layer.

In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the light-emitting layer 6 includes a metal complex of a quinolinol derivative such as _Alq3 , as well as various metal complexes such as zinc, beryllium, and aluminum. It can be formed using light-emitting materials such as metal complexes, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, and polyparaphenylenevinylene derivatives.

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

Such a light emitting layer 6 can also have a single layer structure using one or more types of each light emitting material, or can have a multilayer structure in which a plurality of layers are laminated.

Furthermore, 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 of a metal complex such as iridium or platinum can be used. For example, green phosphorescent emitters such as Ir(ppy) ₃ , blue phosphorescent emitters such as FIrpic and FIr6, and red phosphorescent emitters such as _Btp2Ir (acac) can be used. The material is used by doping a hole injection/transport host material or an electron transport host material.

Note that in order to avoid concentration quenching when doping the host material with the phosphorescent luminescent material, it is preferable to dope the host material by co-evaporation in a range of 1 to 30 weight percent based on the entire luminescent layer.

Furthermore, it is also possible to use materials that emit delayed fluorescence, such as CDCB derivatives such as PIC-TRZ, CC2TA, PXZ-TRZ, and 4CzIPN, as the luminescent material. (See Appl. Phys. Let., 98, 083302 (2011), Chem. Commun., 48, 11392 (2012), Nature, 492, 234 (2012)).

By forming the light emitting layer 6 by making the high molecular weight compound of the present invention support a fluorescent light emitter, a phosphorescent light emitter, or a material that emits delayed fluorescence called a dopant, the driving voltage is lowered and the luminous efficiency is increased. An improved organic EL device can be realized.

In an organic EL device including 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 with hole injection/transport properties. In addition, carbazole derivatives such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP can also be used.

Furthermore, in an 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',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI) and the like can be used.

In an organic EL device including an organic layer formed using the high molecular weight compound of the present invention, the hole blocking layer (not shown in FIG. 20) provided between the light emitting layer 6 and the electron transport layer 7 is It can be formed using a compound having a hole blocking effect that is known per se. Examples of known compounds having such a hole blocking effect include the following.
Phenanthroline derivatives such as bathocuproine (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 derivative;
Triazine derivative;
Oxadiazole derivative.

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

Such a hole blocking layer can also have a single layer or multilayer stacked structure, and each layer is formed using one or more of the compounds having the hole blocking effect described above.

In the organic EL device including an organic layer formed using the high molecular weight compound of the present invention, the electron transport layer 7 is made of a known electron transporting compound such as a quinolinol derivative such as Alq ₃ or BAlq. In addition to metal complexes of be done.

This electron transport layer 7 can also have a single layer or multilayer laminated structure, and each layer is formed using one or more of the above-mentioned electron transport compounds.

Furthermore, in the organic EL device including the organic layer formed using the high molecular weight compound of the present invention, the electron injection layer (not shown in FIG. 20) provided as necessary may also be a well-known one, For example, it can be formed using 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 organometallic complexes such as lithium quinoline. .

As the cathode 8 of an 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 magnesium-silver alloy, magnesium-indium alloy, aluminum-magnesium alloy can be used. Alloys with lower work functions, such as, 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 can be improved. An organic EL element with high efficiency, low practical driving voltage, low emission start voltage, and extremely excellent durability can be obtained. In particular, this organic EL element has high luminous efficiency while reducing driving voltage, improving current tolerance, and increasing maximum luminance.

The present invention will be explained below using the following experimental examples.
In the following description, the repeating unit represented by general formula (1) possessed by the high molecular weight compound of the present invention will be referred to as "repeat unit A", and the repeating unit represented by general formula (2) will be referred to as "repeat unit B". , a repeating unit represented by the general formula (4) having a thermally crosslinkable structural unit Q is shown as a "repeat unit Q".

Further, the synthesized compound was purified by column chromatography and solvent crystallization. Compound identification 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.

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was bubbled through the vessel for 30 minutes.
N,N-bis(4-bromophenyl)-9,9-di-n-octyl-9H-fluoren-2-amine: 16.7g
Bis(pinacolato)diboron: 11.9g
Potassium acetate: 5.7g
1,4-dioxane: 170ml
Next, 0.19 g of 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 of white powder of Intermediate 1 (yield: 40%).

<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 bubbled through the vessel for 30 minutes.
N,N-bis(4-bromophenyl)-N-(benzocyclobuten-4-yl)-amine: 8.0g
Bis(pinacolato)diboron: 9.9g
Potassium acetate: 4.6g
1,4-dioxane: 80ml
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 an 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 from toluene/methanol=1/2 to obtain 3.4 g (yield: 35%) of a white powder of Intermediate 2.

<Synthesis of intermediate 3>

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

The following components were added to a reaction vessel purged with nitrogen, and nitrogen gas was bubbled through the vessel for 30 minutes.
Bis(p-bromophenyl)-2-dibenzofuranamine: 32.0g
Bis(pinacolato)diboron: 34.6g
Potassium acetate: 19.1g
1,4-dioxane: 150ml
Next, 0.5 g of 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 an 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. The crude product was recrystallized with toluene/methanol=1/1 to obtain 18.6 g (yield: 48%) of Intermediate 3, a white powder.

<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 bubbled through the vessel for 30 minutes.
Intermediate 1: 3.6g
Intermediate 2: 0.4g
Intermediate 3: 1.3g
1,3-dibromobenzene: 1.7g
Tripotassium phosphate: 7.4g
Toluene: 9ml
Water: 5ml
1,4-dioxane: 27ml

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. Thereafter, 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 % sodium N,N-diethyldithiocarbamate aqueous solution were added, heated, and stirred under reflux for 2 hours. After cooling to room temperature, an organic layer was collected by performing a liquid separation operation and washed three times with saturated saline. 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 thereto for adsorption purification, and the silica gel was removed by filtration. The obtained filtrate was concentrated under reduced pressure, and 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 3.2 g (yield 76%) of high molecular weight compound I was obtained by drying.

The average molecular weight and dispersity 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
Dispersity (Mw/Mn): 2.2

Further, NMR measurement was performed on high molecular weight compound I. From the ¹ H-NMR measurement results shown in FIG. 21, the chemical composition formula of high molecular weight compound I was as follows.

From the chemical composition, it can be seen that high molecular weight compound I contains 60 mol% of repeating unit A, 30 mol% of repeating unit B, and 10 mol% of repeating unit Q. Note that 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 thickness of 80 nm was prepared on an ITO substrate, and the coating film was measured using an ionization potential measuring device (manufactured by Sumitomo Heavy Industries, Ltd., PYS-202 type). The work function was measured. The work function of high molecular weight compound I was 5.62 eV.

High molecular weight compound I shows a favorable energy level compared to the work function of 5.4 eV of general hole transport materials such as NPD and TPD, and has good hole transport ability and hole injection. It can be seen that it has a sexual nature.

<Example 3>
Using the high molecular weight compound I synthesized in Example 1, a 50 nm thick vapor-deposited film was prepared on a quartz substrate, and the ultraviolet-visible absorption spectrum was measured using a commercially available spectrophotometer. The bandgap was calculated from the wavelength at the edge. In addition, the 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.
Note that NPD, which is a common hole transport material, has a band gap of 3.00 eV and an electron affinity of 2.40 eV.

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

<Example 4>
An organic EL device having the layered structure shown in FIG. 20 was manufactured by the following method.

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

A coating solution was prepared by dissolving 0.4 wt% of a high molecular weight compound (HTM-1) having the following structural formula in toluene. The substrate on which the hole injection layer 3 is formed as described above is transferred to a glove box purged with dry nitrogen, and after drying on a hot plate at 230° C. for 10 minutes, the hole injection layer 3 is removed. A coating layer with a thickness of 15 nm was formed thereon by spin coating using the above coating solution, and further dried on a hot plate at 220° C. for 30 minutes to form a hole transport layer 4.

A coating solution was prepared by dissolving 0.4 wt % of the 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 solution, and then coated on a hot plate at 220° C. for 30 minutes. The electron blocking layer 5 was formed by drying.

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. A light emitting layer 6 with a thickness of 34 nm was formed on the electron blocking layer 5 by binary vapor deposition of a blue light emitting material (EMD-1) and a host material (EMH-1). In the binary vapor deposition, the vapor 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 thickness of 20 nm was formed by binary vapor deposition using electron transport materials (ETM-1) and (ETM-2). In the binary vapor deposition, the vapor deposition rate ratio was set to ETM-1:ETM-2=50:50.

Finally, aluminum was deposited to a 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 are formed is replaced with dry nitrogen. The device was moved into a glove box, and another glass substrate for sealing was bonded using UV curable resin to form an organic EL device. Characteristics of the produced organic EL device were measured in the atmosphere at room temperature. Furthermore, the light emitting characteristics of the manufactured organic EL device when a DC voltage was applied were measured. The above measurement results are shown in Table 1.

<Comparative example 1>
The procedure was exactly the same as in Example 4, except that instead of 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 transporting polymer) in toluene. An organic EL device was produced.

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

In evaluating various characteristics, voltage, brightness, luminous efficiency, and power efficiency are values when a current with a current density of 10 mA/cm ² is passed. In addition, the element life is determined when the light emission brightness at the start of light emission (initial brightness) is 700 cd/ ^m2 and constant current drive is performed, and the light emission brightness is 560 cd/ ^m2 (80% of the initial brightness as 100%). It was measured as the time required to attenuate to (equivalent to: 80% attenuation).

As shown in Table 1, when a current with a current density of 10 mA/ ^cm2 is applied, the luminous efficiency of the organic EL element of Example 4 is 5.50 cd/A, while that of the organic EL element of Example 4 is 7. The efficiency was as high as .52 cd/A. Furthermore, in terms of element life (80% attenuation), the organic EL element of Example 4 had a longer life of 136 hours, compared to 11 hours for the organic EL element of Comparative Example 1.

The high molecular weight compound of the present invention has high hole transport ability and excellent electron blocking ability, so it is excellent as a compound for coating type organic EL devices. By producing a coated organic EL device using this compound, high luminous efficiency and power efficiency can be obtained, and durability can be improved. For example, it has become possible to use it in home appliances and lighting.

1...Glass substrate 2...Transparent anode 3...Hole injection layer 4...Hole transport layer 5...Electron blocking layer 6...Light emitting layer 7...Electron transport layer 8. ··cathode

Claims (11)

Contains a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and has a weight average molecular weight of 10,000 or more and less than 1,000,000 in terms of polystyrene. A high molecular weight compound.
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, or a cycloalkyloxy group having 40 or less carbon atoms. group, alkenyl group, or 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.
Each X 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. The high molecular weight compound according to claim 1, wherein in the general formulas (1) and (2), R ₁ and R ₃ are hydrogen atoms. The high molecular weight compound according to claim 1 or 2, wherein in the general formula (1), R ₂ is an alkyl group having 3 to 40 carbon atoms. In the general formulas (1) and (2), 3. The high molecular weight compound according to claim 1 or 2, which is an acridinyl group. The high molecular weight compound according to claim 1 or 2, which contains 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). The high molecular weight compound according to claim 5, wherein in the general formula (4), the thermally crosslinkable structural unit Q has a structure shown in 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 electroluminescent device having a pair of electrodes and an organic layer sandwiched therebetween, wherein the organic layer uses the high molecular weight compound according to claim 1 or 2 as a constituent material. element. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole transport layer. The organic electroluminescent device according to claim 7, wherein the organic layer is an electron blocking layer. The organic electroluminescent device according to claim 7, wherein the organic layer is a hole injection layer. The organic electroluminescent device according to claim 7, wherein the organic layer is a light emitting layer.