JP5366118B2 - Organic EL device, organic EL display, and hole transporting polymer compound for organic EL device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element which has high efficiency of light emission and long element lifetime by using a hole-transporting high polymer which is soluble in an organic solvent before being cross-linked and is insoluble after being cross-linked. <P>SOLUTION: The organic EL element has a positive electrode 2, a hole implantation layer 3, a light-emitting layer 4, and a negative electrode 5 stacked in order on a substrate 1, and the hole implantation layer is made of a hole-transporting high polymer having a polycarbazole structure shown by general formula (1). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an organic EL element and an organic EL display. In particular, the present invention relates to a highly efficient and long-life organic EL element and an organic EL display using a hole transporting polymer.

  In recent years, organic EL elements have been increasingly installed in mobile phones, portable music players, in-vehicle audio, and the like, and the market for organic EL elements has been expanding. Recently, 11-inch organic EL televisions have been commercialized and attract attention as a third television technology following liquid crystal televisions and plasma televisions.

Organic EL elements can be broadly classified into two types: a low molecular EL element using a low molecular material and a polymer EL element using a high molecular material.
At present, almost all organic EL elements in practical use are low-molecular EL elements, and are manufactured by a production line in which a plurality of vacuum deposition apparatuses are connected.
On the other hand, polymer EL devices have problems of luminous efficiency and device life, and have not been put into practical use. However, as a manufacturing method, a coating method from a solution, for example, a printing method such as a spin coating method, an ink jet method, a flexo method, or a nozzle coating method can be applied, so a large area organic EL element can be manufactured at a low cost. There is a possibility that it can be done, and it is expected as a drastic means for expanding the application development of organic EL elements.

  The basic structure of the polymer EL element is a two-layer structure of a light emitting layer and a hole injection layer. For the light-emitting layer, a polymer material having a high fluorescence quantum yield, excellent charge transportability, soluble in an organic solvent and excellent in thin film forming ability is used. A typical example is a copolymer in which a structure such as acene, aromatic amine, or thiophene is introduced based on a fluorene or phenylene vinylene polymer skeleton.

  On the other hand, the hole injection layer plays a role of injecting holes from an anode such as ITO into the light emitting layer. The conditions required for the hole injection layer are, for example, (1) excellent hole transport ability, (2) highest occupied molecular orbital (HOMO) level close to the work function of the anode, and (3) heat resistance. And (4) electrochemically stable.

  Typical hole injection layers are polyethylene dioxythiophene (PEDOT: PSS), polypyrrole, aromatic amine polymer, and the like. Each polymer is a mixture with an electron-donating dopant and has high conductivity. In particular, PEDOT: PSS is widely used as a mixture with polysulfonic acid (PEDOT: PSS).

  This PEDOT: PSS is formed as a thin film that is insoluble in an organic solvent by applying it in the form of an aqueous solution onto a substrate and then heating and drying. Even if a light-emitting layer is formed on a PEDOT: PSS thin film that has been dried by heating, a PEDOT: PSS layer is not attacked and forms a two-layer structure. be able to. Therefore, holes can be efficiently injected from the anode such as ITO into the light emitting layer through the PEDOT: PSS layer.

  On the other hand, electrons are injected from the cathode side into the light emitting layer, and both holes and electrons are recombined in the light emitting layer to generate an excited state of organic molecules. Light emission occurs when this excited state returns to the ground state.

  A polymer EL device using PEDOT: PSS as a hole injection layer achieves relatively high luminous efficiency and device lifetime. However, in the manufacturing process, PEDOT: PSS uses water that is a major enemy in organic EL. In addition, various problems such as chemical reaction at the interface, diffusion of sulfur, quenching of the excited state have been pointed out.

In view of such circumstances, holes that are not conventional water-soluble hole-transporting polymers such as PEDOT: PSS but are soluble in an organic solvent before crosslinking and insoluble in an organic solvent after crosslinking An organic EL device using a transporting polymer has been studied.
For example, Patent Document 1 discloses a hole transporting polymer having a tertiary aromatic amine structure and an organic EL device using the same. Patent Document 2 describes a hole transporting polymer composed of fluorene-triphenylamine. Furthermore, Patent Document 3 discloses a structure in which a plurality of layers can be formed by forming a film with a fluorene oligomer containing a terminal styrene group as a polymerizable group or a triphenylamine solution and then insolubilizing by a crosslinking reaction. Is disclosed.

  Patent Document 4 discloses a crosslinked polycarbazole and an organic electronic device using the same. Here, it is described that a soluble polycarbazole film is formed on PEDOT: PSS and then heated to obtain a hardly soluble polycarbazole derivative. Since the carbazole derivative has a very high hole mobility, this hardly soluble polycarbazole derivative can be suitably used for an organic EL device. Furthermore, Patent Document 5 discloses obtaining a hole transport material by thermal crosslinking after applying a soluble PPV precursor.

Furthermore, Patent Document 6 discloses a configuration in which a polymer composed of fluorene-triarylamine is inserted as a protective layer and a hole transporting polymer between PEDOT: PSS and the light emitting layer. By using such a protective layer, intrusion of protons or sulfonate groups from the PSS into the light emitting layer can be suppressed, and the device lifetime can be improved.
However, even when these materials and structures are used, an organic EL element using a hole-transporting polymer that is soluble in an organic solvent before crosslinking and insoluble in an organic solvent after crosslinking still has luminous efficiency. In addition, the device life was not sufficient.
Japanese Patent Laying-Open No. 2005-4004 US Pat. No. 5,034,296 US Pat. No. 6,107,452 JP 2006-257196 A JP-A-10-511718 JP 2005-537628 A

  The problem to be solved by the present invention is to improve the efficiency and life of the polymer EL device. By using a new hole transporting polymer in place of the conventional highly conductive material (for example, PEDOT: PSS) at the part in contact with the light emitting layer, the recombination probability of holes and electrons can be improved, The excited state can be efficiently radiated (radiated). Furthermore, a longer lifetime is achieved by using a more chemically stable molecular structure.

  The present invention has been made in view of the above circumstances, and uses a hole transporting polymer that is soluble in an organic solvent before cross-linking and becomes insoluble in the organic solvent after cross-linking. An object of the present invention is to provide an organic EL device having a long length.

The inventors have developed a new hole-transporting polymer for the hole-injecting layer and replaced it with a conventional one or inserted it thinly between the conventional highly conductive hole-injecting layer and the light-emitting layer. investigated.
A new hole transporting polymer for the hole injection layer is soluble in an organic solvent instead of water, has a large energy gap between HOMO and LUMO, has a high hole transporting property, and after forming a thin film It must be insoluble in organic solvents. Further, in order to facilitate hole injection into the light emitting layer, it is desirable that HOMO is a value close to the ionization potential of the anode.

The new hole transporting polymer for the hole injection layer is specifically a polycarbazole derivative that is soluble in an organic solvent, and after the formation of the thin film, it is made to react between organic molecules to form an organic solvent, etc. Insoluble polymer.
The carbazole ring of the polycarbazole derivative is a molecular structure having a hole-transporting ability, and a reaction site that causes a binding reaction between molecules is added to the molecular structure. When the reaction site is heated, it chemically reacts with and binds to other reaction sites between or within the molecule. As a result, the organic EL element becomes insoluble in an organic solvent while maintaining the hole transport property, and can be driven at a low voltage, with high efficiency, and with a long life.

［式（２ｃ）中、ｎは１〜１０００の整数であり、Ｒは置換基であって、水素原子または置換されていてもよいアルキル基、置換されていてもよいアルコキシ基のいずれかであり、Ａｒ _１ およびＡｒ _２ は、各々独立に、置換されていてもよい芳香族炭化水素基、または置換されていてもよい芳香族複素環基を示す。
また、Ｘは、触媒の有る無しに関係なく、光あるいは熱によりクロスリンクが可能な重合性官能基をもった置換基であり、ビニル基、トリフルオロビニル基、アクリル基、メタクリル基、オキセタン基、あるいはエポキシ基などを有する、置換されていてもよいアルキル基、置換されてもよいアルコキシ基、置換されていてもよい芳香族炭化水素基、または置換されていてもよい芳香族複素環基を示し、ａおよびｂは各々独立に１〜５の整数を示す。］
本発明の有機ＥＬ素子用の正孔輸送性高分子化合物は、下記一般式（２ｄ）に示されるポリカルバゾール骨格を有することを特徴とする。

［式（２ｄ）中、ｎは１〜１０００の整数であり、Ｒは置換基であって、水素原子または置換されていてもよいアルキル基、置換されていてもよいアルコキシ基のいずれかである。
また、Ｘは、触媒の有る無しに関係なく、光あるいは熱によりクロスリンクが可能な重合性官能基をもった置換基であり、ビニル基、トリフルオロビニル基、アクリル基、メタクリル基、オキセタン基、あるいはエポキシ基などを有する、置換されていてもよいアルキル基、置換されてもよいアルコキシ基、置換されていてもよい芳香族炭化水素基、または置換されていてもよい芳香族複素環基を示し、ａおよびｂは各々独立に１〜５の整数を示す。］
本発明の有機ＥＬ素子は、基板上に、陽極と、正孔注入層と、発光層と、陰極とがこの順序で積層されており、前記正孔注入層が、上記有機ＥＬ素子用の正孔輸送性高分子化合物からなることを特徴とする。 In order to achieve the above object, the present invention employs the following configuration. That is,
The hole transporting polymer compound for an organic EL device of the present invention is characterized by having a polycarbazole skeleton represented by the following general formula (2c).

[In Formula (2c), n is an integer of 1 to 1000, R is a substituent, and is either a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group. , Ar ₁ and Ar ₂ each independently represent an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group.
X is a substituent having a polymerizable functional group that can be cross-linked by light or heat regardless of the presence or absence of a catalyst, and includes a vinyl group, a trifluorovinyl group, an acrylic group, a methacryl group, and an oxetane group. Or an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic hydrocarbon group, or an optionally substituted aromatic heterocyclic group having an epoxy group, etc. A and b each independently represent an integer of 1 to 5. ]
The hole transporting polymer compound for an organic EL device of the present invention has a polycarbazole skeleton represented by the following general formula (2d).

[In the formula (2d), n is an integer of 1 to 1000, R is a substituent, and is either a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group. .
X is a substituent having a polymerizable functional group that can be cross-linked by light or heat regardless of the presence or absence of a catalyst, and includes a vinyl group, a trifluorovinyl group, an acrylic group, a methacryl group, and an oxetane group. Or an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic hydrocarbon group, or an optionally substituted aromatic heterocyclic group having an epoxy group, etc. A and b each independently represent an integer of 1 to 5. ]
In the organic EL device of the present invention, an anode, a hole injection layer, a light emitting layer, and a cathode are laminated in this order on a substrate, and the hole injection layer is a positive electrode for the organic EL device. It consists of a hole-transporting high molecular compound .

The organic EL device of the present invention is characterized in that the hole injection layer made of the hole transporting polymer compound is insoluble in an organic solvent.

The organic EL device of the present invention, the hole injection layer made of a hole transporting polymer compound, and heating the hole-transporting polymer compound precursors for the organic EL element, intramolecular or intermolecular It is formed by cross-linking a polymerization group.

  The organic EL device of the present invention is characterized in that the polymerization group is a vinyl group.

The organic EL device of the present invention is characterized in that the hole transporting polymer compound precursor is soluble in an organic solvent.

  The organic EL device of the present invention is characterized in that another hole injection layer is inserted between the hole injection layer and the anode.

The organic EL display of the present invention is characterized in that the organic EL elements described above are formed in a matrix on a substrate .

  According to the above configuration, an organic EL device having a high light emitting efficiency and a long device life is provided by using a hole transporting polymer that is soluble in an organic solvent before crosslinking and insoluble in the organic solvent after crosslinking. can do.

Hereinafter, an example of the organic EL element which is an embodiment of the present invention will be described.
(Embodiment 1)
FIG. 1 is a schematic cross-sectional view illustrating an example of an organic EL element according to an embodiment of the present invention.
As shown in FIG. 1, an organic EL element 11 according to an embodiment of the present invention is formed by sequentially laminating an anode 2, a hole injection layer 3, a light emitting layer 4 and a cathode 5 on a substrate 1.

(substrate)
The substrate 1 can be made of a transparent material having excellent characteristics for blocking air, moisture, and the like. The substrate is not limited to an inorganic material such as glass or quartz, and a plastic substrate or a metal thin film can be used.

(anode)
The anode 2 is formed as a thin film on one surface of the substrate 1. As a material of the anode 2, a material having a large work function is desirable in order to facilitate hole injection into the organic layer. The work function is preferably at least 4.0 eV. Generally, a transparent or translucent material is preferable because it is formed on a glass substrate and needs to transmit light. However, in the case of a top emission structure in which light is extracted from the upper surface of the organic EL element, it is not necessary to use a transparent material. Specifically, indium-tin-oxide (hereinafter referred to as ITO), indium-zinc-oxide (hereinafter referred to as IZO), indium oxide, and tin oxide are preferable, but with gold, platinum, silver, or other metals An alloy thin film may be used.

(Hole injection layer)
The hole injection layer 3 is made of an organic material having a high hole injection capability. In addition, a material capable of taking holes from the anode 2 into the hole injection layer 3 with high efficiency and applying holes from the hole injection layer 3 to the light emitting layer 4 with high efficiency by applying an electric field. It is.

<Hole transporting polymer>
The hole injection layer 3 is made of a hole transporting polymer having a polycarbazole skeleton represented by the general formula (1).
In the general formula (1), n is an integer of 1 to 1000, the ratio of x and y is arbitrary, R is a substituent, and is a hydrogen atom or an optionally substituted alkyl group, substituted. Examples of the alkyl group which may be any of the alkoxy groups which may be substituted and may be substituted include linear or branched alkyl groups having 1 to 15 carbon atoms. For example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-decyl, 2-methylhexyl, 2-ethylhexyl, 2-n Examples include -propylhexyl, 2-n-butylhexyl, 2-ethyldecyl, 3-ethylhexyl and the like, and further examples thereof include an alkyl group which may be substituted with a polymerizable functional group represented by X.
Examples of the alkoxy group which may be substituted include a linear or branched alkoxy group having 1 to 15 carbon atoms. For example, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butoxy, n-pentyloxy, n-hexyloxy, n-octyloxy, n-decyloxy, 2-methylhexyloxy, 2-ethylhexyl Examples include oxy, 2-n-propylhexyloxy, 2-n-butylhexyloxy, 2-ethyldecyloxy, 3-ethylhexyloxy, phenoxy, and the like, and these substituents are polymerizable functional groups represented by X. The alkoxy group which may be substituted is mentioned.
Furthermore, as R, Preferably, hydrogen, methyl, ethyl, iso-propyl, tert-butyl etc. are mentioned.

In the general formula (1), Ar ₁ and Ar ₂ each independently represent an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group. Examples include benzene, biphenyl, terphenyl, naphthalene, fluorene, furan, thiophene, pyridine, quinoline, isoquinoline, carbazole and the like.
Ar ₁ and Ar ₂ are preferably divalent substituents which may be substituted as represented by the following general formulas (3-1) to (3-6).

In the above general formulas (3-1) to (3-6), R ₁ and R ₂ represent hydrogen, an alkyl group having 1 to 10 carbon atoms which may be substituted, and c, d and e are each independent. Represents an integer of 1 to 3.

In the general formula (1), X is a substituent having a polymerizable functional group (polymerization group) that can be cross-linked by light or heat regardless of the presence or absence of a catalyst. Having an alkyl group, an acrylic group, a methacryl group, an oxetane group, or an epoxy group, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic hydrocarbon group, or a substituted group An aromatic heterocyclic group which may be substituted, a and b each independently represent an integer of 1 to 5;
Examples of X preferably include the following general formulas (4-1) to (4-6).

In the general formulas (4-1) to (4-6), Y and Z are each independently a single bond, oxygen, nitrogen, sulfur, an optionally substituted aromatic hydrocarbon group, or a substituted group. A preferable aromatic heterocyclic group, R ₃ represents hydrogen, an optionally substituted alkyl group having 1 to 10 carbon atoms, and f represents an integer of 0 to 10.
X is more preferably a substituent having a polymerizable functional group represented by the following general formula (5).

In the general formula (5), Z represents a single bond or an oxygen atom, and g represents an integer of 0 to 10.
Examples of the substituent having such a polymerizable functional group include the following general formulas (6-1) to (6-7).

  Examples of the substituent which may be substituted with the aromatic hydrocarbon group or aromatic heterocyclic group shown above include, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, methoxy , Ethoxy, benzene, naphthalene, biphenyl, terphenyl, fluorene, benzyl, phenethyl, furan, thiophene, pyridine, quinoline, isoquinoline, carbazole, diphenylamine or triphenylamine An aromatic vinyl compound is exemplified.

In the general formula (1), Ar ₃ is a monomer moiety containing a carbazole ring represented by the general formula (2), and is bonded to an adjacent monomer moiety via the 2,7-position or the 3,6-position. To do.
In the general formula (2), R ₄ represents an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, or an optionally substituted aromatic heterocyclic group, and R ₅ , R ₆ are each independently hydrogen, an alkyl group that may be substituted, an alkoxy group that may be substituted, an aromatic hydrocarbon group that may be substituted, or an aromatic that may be substituted Represents a heterocyclic group, or represents a nitro group, a cyano group, a halogen group (fluorine, chlorine or bromine), an aromatic amino group, an aromatic vinyl group, and h and i each independently represents an integer of 0 to 3. Show.

  Examples of the alkyl group which may be substituted include a linear or branched alkyl group having 1 to 15 carbon atoms. For example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-decyl, 2-methylhexyl, 2-ethylhexyl, 2-n Examples include -propylhexyl, 2-n-butylhexyl, 2-ethyldecyl, 3-ethylhexyl and the like. Further, an alkyl substituent which may be substituted with a polymerizable functional group represented by X is mentioned.

  Examples of the alkoxy group which may be substituted include a linear or branched alkoxy group having 1 to 15 carbon atoms. For example, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butoxy, n-pentyloxy, n-hexyloxy, n-octyloxy, n-decyloxy, 2-methylhexyloxy, 2-ethylhexyl Examples include oxy, 2-n-propylhexyloxy, 2-n-butylhexyloxy, 2-ethyldecyloxy, 3-ethylhexyloxy, phenoxy and the like. Furthermore, the alkoxy group which these substituents may be substituted by the polymeric functional group shown by X is mentioned.

  Examples of the optionally substituted aromatic hydrocarbon group include an aromatic hydrocarbon group having 6 to 30 carbon atoms. Examples include aromatic amine compounds typified by benzene, naphthalene, biphenyl, terphenyl, benzyl, fluorene, phenethyl, diphenylamine, triphenylamine and the like, and aromatic vinyl compounds typified by styrene and the like.

  Examples of the optionally substituted aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 30 carbon atoms. For example, furan, thiophene, pyridine, quinoline, isoquinoline, carbazole and the like are exemplified.

  Examples of the substituent that may be substituted with the aromatic hydrocarbon group or aromatic heterocyclic group shown above include methyl, ethyl, n-propyl, iso-propyl, n-butyl, and tert-butyl. , Methoxy, ethoxy, benzene, naphthalene, biphenyl, terphenyl, fluorene, benzyl, phenethyl, furan, thiophene, pyridine, quinoline, isoquinoline, diphenylamine or triphenylamine An aromatic vinyl compound is exemplified, and further, a substituent which may be substituted with a polymerizable functional group represented by X is mentioned.

More preferable examples of Ar ₃ include the following structural formulas (7-1) to (7-12) and the following structural formulas (8-1) to (8-16).

  The hole transporting polymer having a polycarbazole skeleton represented by the general formula (1) is a polycarbazole derivative having a carbazole ring which is a molecular structure having essentially a hole transporting ability. Therefore, the hole injection layer 3 having excellent hole transportability can be obtained.

A substituent having a triphenylamine structure is added to the carbazole ring. Furthermore, each of the substituents having a triphenylamine structure is independently substituted with Ar ₁ and Ar ₂ which are optionally substituted aromatic hydrocarbon groups or optionally substituted aromatic heterocyclic groups. Thus, a substituent X having a polymerizable functional group is added. The polymerizable group chemically reacts with other reaction sites in the molecule or between the molecules, and the hole transporting polymer chain is bound like a network to form a polymer insoluble in the organic solvent.
Therefore, even if the light emitting layer solution prepared by dissolving in an organic solvent is applied onto the hole transporting polymer, the hole injection layer 3 can be prevented from being dissolved. Therefore, an organic EL device in which the light emitting layer solution prepared by dissolving in an organic solvent is applied to the hole injection layer 3 and the light emitting layer 4 is laminated on the hole injection layer 3 can be produced.

<Hole-transporting polymer precursor>
The hole transporting polymer is formed by heating the hole transporting polymer precursor to crosslink the polymerization group within or between the molecules.
The hole transporting polymer precursor has a polycarbazole skeleton represented by the above general formula (1), and has a basic molecular structure composed of a carbazole ring and a substituted product as a repeating unit (monomer unit). A basic molecular structure composed of a carbazole ring and a substituted product thereof is a molecular structure having a hole transport ability.

  A substituent having a triphenylamine structure is added to a basic molecular structure composed of a carbazole ring and a substituted product thereof. In addition, a polymerized group (reactive site) is provided at the end of the alkyl chain substituted with the phenyl group of triphenylamine, and this polymerized group (reactive site) can be exchanged within the molecule or between molecules by heating. The polymer reacts with the reactive site to form a polymer.

The polymerization group (reaction site) of the hole transporting polymer precursor is preferably a vinyl group. By heating, a hole-transporting polymer composed of a polymer can be easily formed by crosslinking a polymerization group within a molecule or between molecules.
The crosslinking reaction of a vinyl group occurs when a double bond of one vinyl group is opened by heating and is bonded to another vinyl group. In a thin film made of a hole transporting polymer precursor, there are a plurality of hole transporting polymers having a large number of vinyl groups, so that a cross-linking reaction occurs between adjacent vinyl groups. As a result, a hole transporting polymer composed of a polymer having a network structure is formed.
Since the hole transporting polymer formed in this manner retains a molecular structure composed of a carbazole ring and a triphenylamine substituent, it can retain a high hole transporting property. Therefore, the luminous efficiency can be greatly improved.

  A polymerization initiator or the like may be added to the hole transporting polymer precursor solution. Further, in the cross-linking reaction, ultraviolet rays having a wavelength of 400 nm or less may be supplementarily irradiated. Both can promote the crosslinking reaction.

The hole transporting polymer precursor is soluble in an organic solvent. The hole-transporting polymer precursor is not cross-linked between molecules or between molecules, and also has no hydrophilic group in the molecule, so that it can be easily dissolved and dispersed in an organic solvent. For example, the hole transporting polymer precursor is soluble in an organic solvent such as chloroform, hexane, toluene and dichlorobenzene at a concentration of 0.1 to 5% by mass.
A uniform hole transporting polymer precursor thin film can be formed by applying a solution in which the hole transporting polymer precursor is dissolved onto the substrate using a coating method such as spin coating. Further, by using a solution dissolved in an organic solvent, the influence of water can be eliminated from the organic EL element, and the life of the organic EL element can be improved.

  Specific examples of the hole transporting polymer precursor used for the hole injection layer 3 are those represented by the following general formulas (9) to (11), for example.

<Hole transporting polymer thin film formation>
First, a uniform thin film can be formed by applying a solution in which a hole-transporting polymer precursor is dissolved onto a substrate using a coating method such as a spin coating method.
Next, a thin film made of a hole transporting polymer can be formed by performing a crosslinking reaction by heating and drying.

  For example, a hole injection layer solution prepared by dissolving a hole transporting polymer precursor in a toluene solution is applied on a substrate using a spin coat coating method to form a thin film, followed by heat drying at 80 ° C., Furthermore, by heating at a temperature of 200 to 300 ° C., a double bond vinyl group causes a cross-linking reaction between molecules and within a molecule, so that a thin film made of a hole transporting polymer can be formed.

FIG. 3 is a diagram schematically showing changes in the microscopic structure during the thin film formation process by the above method.
FIG. 3A is a schematic diagram showing a state in which a hole transporting polymer precursor is dissolved in a solution, in which independent polymer chains 21 are shown, and polymer groups 22 are bonded to the polymer chains 21. Has been.
FIG. 3B is a schematic diagram showing a state after a solution of a hole transporting polymer precursor is applied on a substrate by a spin coat method or the like to form a thin film and then dried by heating. The independent polymer chain 21 is bonded to another polymer chain 23 by the bridging portion 22a, thereby forming a net-like structure.

The work function of the hole injection layer 3 (second hole injection layer 32) is preferably a value that facilitates injection from the anode 2 to the light emitting layer 4, such as ITO (work function 4.8 eV). A work function of 5.0 to 5.5 eV is preferable.
The work function of the hole injection layer 3 (second hole injection layer 32) can be determined by molecular design according to the HOMO level (ionization potential of the thin film) of the light emitting layer 4. For example, the work function of the hole injection layer 3 can be changed by changing the type and position of the substituent R of the carbazole ring of the hole injection layer 3 or changing the copolymerization ratio (n: m) of the substituted and unsubstituted substances. Can be controlled.

(Light emitting layer)
As the light emitting layer 4, it is preferable to use a polymer light emitting material that can be applied from a solution of an organic solvent by a coating method.
For example, use a fluorene-based or phenylene vinylene-based polymer, particularly a copolymer of acene, thiophene, or aromatic amine, and a conjugated polymer light-emitting material to which a long-chain alkyl or alkoxy group is added. Can do. Each of these materials exhibits an emission spectrum depending on the molecular structure by electroluminescence.

  In addition to such a conjugated polymer light emitting material, a phosphorescent polymer can also be used. In addition, light emitting materials that can be coated and formed even with low molecular light emitting materials have been developed, and these may be used. Further, as a method for forming the light emitting layer 4, not only a wet process by the above-described coating method but also a dry process such as a vacuum deposition method may be used.

(cathode)
As a material for the cathode 5, an alkaline metal such as Li, Na, K, Rb, or Cs having a low work function that has a work function of at least 4.5 eV or less, or an alkaline earth metal such as Mg, Ca, Sr, or Ba is used. Is preferable from the viewpoint of electron injecting property. Alternatively, chemically stable Al or the like may be used.
However, since the metal having a low work function easily reacts with oxygen or moisture in the air and lacks stability, the alloy includes MgAg or a compound containing the metal such as LiF, Li ₂ O, or CsF. It is preferable to form.

In general, the cathode 5 has a structure in which two or more materials are laminated in order to achieve both stability and electron injection. These materials are described in JP-A-2-15595, JP-A-5-121172, and the like.
For example, a metal thin layer (about 0.01 to 100 nm) such as Cs or Ba is sandwiched before Al, an alkali metal fluoride such as LiF, or an alkaline earth metal oxide such as Al ₂ O ₃ is used as a metal. It is also widely done in front of. Further, a mixed layer of an organic compound and an alkali metal or alkaline earth metal may be provided as an injection layer before the metal.

  The anode 2 and the cathode 5 can be formed by a known method such as vacuum deposition, electron beam deposition, sputtering, or ion plating. The patterning of the electrodes (particularly the EL transmissive electrode) is preferably performed by chemical etching using photolithography, physical etching using a laser, or the like. Alternatively, patterning may be performed by stacking a metal shadow mask and performing vacuum deposition, sputtering, or the like.

The organic EL display is preferably formed by forming organic EL elements having the above materials and structures on a substrate in a matrix.
By forming an organic EL device having the above-described materials and structure in a matrix on a substrate, a hole transporting polymer that is soluble in an organic solvent before crosslinking and insoluble in an organic solvent after crosslinking is formed. Used, an organic EL element with high light emission efficiency and long element life can be formed for each pixel, so that it is driven at low voltage, has high light emission efficiency, long element life, low power consumption, and high reliability. It can be set as an organic EL display.

(Hole blocking layer (hole blocking layer), electron transport layer)
Note that either the hole blocking layer or the electron transport layer may be inserted between the light emitting layer 4 and the cathode 5 singly or in combination.
The hole blocking layer is preferably an organic thin film that can block holes that have hopped and moved inside the light emitting layer 4. For example, by comparing the ground state HOMO level of the light-emitting layer 4 with the ground state HOMO level of the hole-blocking layer, the ground-state HOMO level of the hole-blocking layer is Any material deeper than the HOMO level can be used as the hole blocking layer. This is because, due to this energy difference, the holes that have moved can be prevented from entering the hole blocking layer. Holes that are blocked from entering the hole blocking layer stay inside the light emitting layer 4 and contribute to the generation of excitons.

  As the organic material that can be used as the hole blocking layer (hole blocking layer), a general electron transporting material that satisfies the above conditions can be used. For example, 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris [1-phenyl-1H-benzimidazole] (hereinafter, TPBI) can be used.

The electron transport layer is an organic material having a high electron transport capability, and is preferably a material that can stably exist as a thin film without being broken even when an electric field is applied. For example, as a material of the electron transport layer, tris- (8-hydroxyquinoline) -aluminum (hereinafter referred to as Alq ₃ ) can be used.

<Active type display>
In addition, it is good also as an active type display which arrange | positions two or more thin-film transistors (TFT) for every organic EL pixel, and performs an address and a drive. An organic thin film transistor may be used, and a plastic substrate may be applied.

  In addition, in the case of an active type display, since the aperture ratio is reduced by arranging TFTs on the substrate side, the top emission that takes out light emission from the surface opposite to the substrate (upper surface when the substrate is the lower surface) is used. It is good also as a structure. In this case, generally, a transparent electrode is used on the upper surface side, and an opaque metal is used as an electrode on the substrate side.

(Embodiment 2)
FIG. 2 is a schematic cross-sectional view illustrating another example of the organic EL element according to the embodiment of the present invention.
As shown in FIG. 2, the organic EL device 12 according to the embodiment of the present invention includes another hole injection layer (second hole layer) between the hole injection layer 3 (second hole injection layer 32) and the anode 2. The structure is the same as that of the first embodiment except that 1 hole injection layer 31) is inserted.
Another hole injection layer (first hole injection layer 31) is formed to be thin. As a material for another hole injection layer (first hole injection layer 31), a highly conductive hole transporting polymer such as PEDOT: PSS, which has been conventionally used in organic EL elements, is used. Can do.

  Since the second hole injection layer 32 is formed between the light emitting layer 4 and the highly conductive PEDOT: PSS, the PEDOT that constitutes the first hole injection layer 31 when the light emitting layer 4 is applied. The problem of dissolving PSS does not occur. Thereby, the molecular excited state can be efficiently radiated (radiated) and a high-efficiency polymer EL element can be produced.

Thus, it is preferable to insert another hole injection layer (first hole injection layer 31) between the hole injection layer 3 (second hole injection layer 32) and the anode 2.
Thus, by making a hole injection layer into a two-layer structure, the hole injection efficiency to the light emitting layer 4 can be improved, and the light emission efficiency of an organic EL element can be improved.
For example, PEDOT: PSS has a work function of about 5.1 eV, and holes from the anode 2 such as ITO (work function 4.8 eV) to the hole injection layer 3 (work function 5.0-5.5 eV). Since the injection can be bridged, it is possible to inject holes into the light emitting layer 4 at a lower voltage.

Hereinafter, the synthesis | combination of the compound used for the positive hole injection layer of the organic EL element which is embodiment of this invention is demonstrated.
<Synthesis of compounds>
Hereinafter, N, N-dimethylformamide is referred to as DMF, tetrahydrofuran as THF, N-bromosuccinimide as NBS, and trans-1,2-cyclohexanediamine as CHDA.
2,7-dichlorocarbazole was synthesized by an existing method described in Macromolecules 2001, 34, 4680.

<Synthesis Example 1: Synthesis of 2,7-dichloro-3,6-dibromocarbazole>

23.6 g (100 mmol) of 2,7-dichlorocarbazole was placed in Schlenk, the container was purged with argon, and 250 mL of DMF was added thereto and dissolved. After cooling the vessel with an ice bath, a solution of 35.6 g (200 mmol) of NBS in 150 mL of DMF was added. When the ice bath was removed and the mixture was stirred at room temperature, a precipitate was formed in about 6 hours. After stirring for 24 hours, the reaction solution was concentrated to remove DMF, and 500 mL of ether was added thereto to dissolve the precipitate. This solution was washed with 500 mL of water three times, and then the ether layer was dried over anhydrous sodium sulfate. Filtration removed the sodium sulfate and the ether layer was concentrated until a precipitate formed. The precipitate was filtered and collected after washing with ether. The filtrate was concentrated and the resulting precipitate was filtered again, washed with ether and collected.
This operation was repeated to recover 36.9 g (93.7 mmol) of the target product as a white powder (yield 94%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 8.22 (s, 2H), δ 8.07 (bs, 1H), δ 7.55 (s, 2H).

<Synthesis Example 2: Synthesis of 2,7-dichloro-3,6-dimethylcarbazole>

Argon-substituted Schlenk was charged with 12.6 g (32.0 mmol) of 2,7-dichloro-3,6-dibromocarbazole and 0.261 g (0.32 mmol) of Pd (dppf) dichloromethane complex, to which 100 mL of THF was added. Was added. The Schlenk was cooled to −78 ° C., 100 mL (96.0 mmol) of methylmagnesium bromide 0.96M-THF solution was added little by little, all were added, and the mixture was warmed to room temperature. A Schlenk condenser was attached and refluxed for 24 hours. 300 mL of water was added to the reaction solution, and the mixture was extracted 3 times with 300 mL of chloroform. The chloroform layer was dried over anhydrous sodium sulfate, filtered to remove sodium sulfate, and the chloroform layer was concentrated until a precipitate was formed. The precipitate was filtered, washed with chloroform and collected. The filtrate was concentrated and the resulting precipitate was filtered again, washed with chloroform and collected.
This operation was repeated to recover 5.54 g (22.5 mmol) of the target product as a white powder (yield 70%).

<Synthesis Example 3: Synthesis of N- (4-triphenylamine) -2,7-dichloro-3,6-dimethylcarbazole>

2.64 g (10.0 mmol) of 2,7-dichloro-3,6-dimethylcarbazole, 3.24 g (10.0 mmol) of 4-bromotriphenylamine, a catalytic amount of copper iodide, 6.37 g (30.0 mmol) of potassium phosphate, 0.114 g (1.0 mmol) of CHDA and 50 mL of 1,4-dioxane were added and the vessel was sealed and stirred at 115 ° C. for 60 hours. 200 mL of water was added to the reaction solution, extraction was performed 3 times with 200 mL of ether, and the ether layer was dried over anhydrous sodium sulfate. After removing the desiccant by filtration and concentrating, the product was isolated and produced by column chromatography (developing solvent hexane) to obtain 3.69 g (7.27 mmol) of the desired product as a white powder (yield 73%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 7.88 (s, 2H), δ 7.38-7.20 (m, 14H), δ 7.12-7.06 (m, 2H), δ 2.53 ( s, 6H).

<Synthesis Example 4: Synthesis of N- [4- {N, N-bis (4'-bromophenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole>

Schlenk was charged with 1.52 g (3.0 mmol) of N- (4-triphenylamine) -2,7-dichloro-3,6-dimethylcarbazole, the vessel was purged with argon, and 100 mL of DMF was added thereto, Dissolved. After cooling the vessel with an ice bath, a solution of 1.10 g (6.2 mmol) of NBS in 50 mL of DMF was added. When the ice bath was removed and the mixture was stirred at room temperature, a precipitate was formed in about 4 hours. After stirring for 24 hours as it was, 300 mL of water was added, and the mixture was extracted 4 times with 250 mL of ether. The ether layer was concentrated to about 300 mL and washed with 300 mL of water. The ether layer was dried over anhydrous sodium sulfate, filtered to remove sodium sulfate, and the ether layer was concentrated.
The product was isolated and produced by column chromatography (developing solvent hexane) to obtain 1.53 g (2.30 mmol) of the desired product as a white powder (yield 77%).

Synthesis Example 5 Synthesis of N- [4- {N, N-bis (4 ′-( 5 -hexenyl) phenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole>

Argon-substituted Schlenk was charged with 1.0 g (41.1 mmol) of magnesium, and a solution of 5.0 g (30.7 mmol) of 6 -bromo- 1 -hexene dissolved in 30 mL of THF was refluxed with heat of reaction. It was dripped little by little at the speed of. Thereafter, the mixture was further refluxed for 1 hour to prepare a Grignard reagent. Argon-substituted Schlenk was newly prepared and 0.665 g (1.0 mmol) of N- [4- {N, N-bis (4′-bromophenyl) amino} phenyl] -3,6-dimethyl- 2,7-dichlorocarbazole, a catalytic amount of PdCl ₂ (dppf) and 5 mL of THF were added and stirred. To this was added 6.0 mL (6.0 mmol) of the Grignard reagent prepared earlier, and the mixture was stirred at 80 ° C. for 48 hours, followed by addition of water and extraction with ether. The ether layer was dried over sodium sulfate, filtered, concentrated, and then isolated by column chromatography (developing solvent: hexane) to obtain 0.257 g (0.383 mmol) of the desired product (yield 38%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 7.88 (s, 2H), δ 7.37 (s, 2H), δ 7.19-7.13 (s, 10H), δ 5.86-5.78 ( m, 2H), δ 5.05-4.94 (m, 4H), δ 2.60 (t, 4H), δ 2.53 (s, 6H), δ 2.14-2.08 (m, 4H), δ1 .70-1.62 (m, 4H), δ 1.54 (s, 2H) δ 1.51-1.45 (m, H).

Synthesis Example 6 Synthesis of N- [4- {N, N-bis (4 ′-( 4 -pentenyl) phenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole

Argon-substituted Schlenk was charged with 1.0 g (41.1 mmol) of magnesium, and a solution of 5.0 g (33.6 mmol) of 5 -bromo- 1 -pentene dissolved in 30 mL of THF was refluxed with heat of reaction. It was dripped little by little at the speed of. Thereafter, the mixture was further refluxed for 1 hour to prepare a Grignard reagent. Argon-substituted Schlenk was newly prepared and 0.80 g (1.2 mmol) of N- [4- {N, N-bis (4′-bromophenyl) amino} phenyl] -3,6-dimethyl- 2,7-dichlorocarbazole, a catalytic amount of PdCl2 (dppf) and 5 mL of THF were added and stirred. To this was added 6.0 mL (6.0 mmol) of the Grignard reagent prepared earlier, and the mixture was stirred at 80 ° C. for 48 hours, followed by addition of water and extraction with ether. The ether layer was dried over sodium sulfate, filtered and concentrated, and then isolated by column chromatography (developing solvent: hexane) to obtain 0.541 g (0.84 mmol) of the desired product (yield 70%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 7.88 (s, 2H), δ 7.37 (s, 2H), δ 7.14 (s, 10H), δ 5.91-5.81 (m, 2H) , Δ 5.07-4.98 (m, 4H), δ 2.61 (s, 4H), δ 2.53 (s, 6H), δ 2.16-2.11 (m, 4H), δ 1.78-1 .71 (m, 4H), δ 1.54 (s, 2H).

<Synthesis Example 7: Synthesis of N- [4- {N, N-bis (4'-isopropylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole>

1.06 g (4.0 mmol) 2,7-dichloro-3,6-dimethylcarbazole and 1.63 g (4.0 mmol) 4-bromo-4 ′, 4 ″ -diisopropyltriphenyl were added to the argon-substituted Schlenk. Amine, catalytic amount of copper iodide, 2.55 g (12.0 mmol) potassium phosphate, 0.045 g (0.4 mmol) CHDA, and 16 mL 1,4-dioxane were added and the vessel was sealed and 115 Stir at 60 ° C. for 60 hours. 100 mL of water was added to the reaction solution, and the mixture was extracted 3 times with 100 mL of ether, and the ether layer was dried over anhydrous sodium sulfate. After removing the desiccant by filtration and concentrating, it was isolated and produced by column chromatography (developing solvent hexane) to obtain 1.68 g (2.84 mmol) of the desired product as a white powder (yield 71%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 7.88 (s, 2H), δ 7.37 (s, 2H), δ 7.26-7.13 (s, 10H), δ 2.94-2.87 ( m, 2H), δ 2.53 (s, 6H), δ 1.27 (d, 12H).

<Synthesis Example 8: Synthesis of N- [4- {N, N-bis (4'-formylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole>

  In an argon-substituted Schlenk, 1.01 g (2 mmol) of N- (4-triphenylamine) -2,7-dichloro-3,6-dimethylcarbazole, 10 mL of DMF and 10 mL of toluene were added and dissolved. After the Schlenk was cooled in an ice bath, 1.84 g (12.0 mmol) of phosphorus oxychloride was added dropwise. Then, it heated up to 100 degreeC and stirred for 20 hours. The reaction solution was added dropwise to 100 mL of ice water and neutralized with 2N aqueous sodium hydroxide solution. Extraction was performed 4 times with 100 mL of ether, and the ether layer was dried over anhydrous sodium sulfate, filtered, concentrated, and isolated by column chromatography (developing solvent: hexane / dichloromethane = 1/3), 0.96 g (1 .70 mmol) was obtained (yield 85%).

<Synthesis Example 9: Synthesis of N- [4- {N, N-bis (4'-vinylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole>

0.786 g (2.2 mmol) of bromomethyltriphenylphosphine and 5 mL of THF were added to Schlenk that had been purged with argon and cooled with ice, and 0.247 g (2.2 mmol) of tert-butoxypotassium was further added and stirred. Add 0.564 g (1.0 mmol) of N- [4- {N, N-bis (4′-formylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole dissolved in THF. After stirring at room temperature for 5 hours, water was added and the mixture was extracted with ether. The ether layer was dried over anhydrous sodium sulfate, filtered and concentrated, and then isolated by column chromatography (developing solvent: hexane) to obtain 0.466 g (0.833 mmol) of the desired product (yield 83%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 7.88 (s, 2H), δ 7.39-7.10 (m, 13H), δ 6.70 (dd, 1H), δ 5.69 (d, 1H) , Δ 5.21 (d, 1H), δ 2.53 (s, 6H).

Next, 0.198 g (0.72 mmol) of bis (1,5-cyclooctadiene) nickel (0) and 0.112 g (0.72 mmol) of 2,2′-bipyridyl were added to the argon-substituted Schlenk in an argon stream. Put in, add 1.2 mL DMF and then stir at room temperature for 30 min. Thereto, 0.2798 g (0.5 mmol) of N- [4- {N, N-bis (4′-vinylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole was added to 3 A solution dissolved in 0.0 mL of DMF was added and the vessel was sealed and stirred at 65 ° C. for 72 hours. The reaction solution was added dropwise to a mixed solvent of 500 mL of methanol and 20 mL of concentrated hydrochloric acid and stirred for 24 hours. The precipitate was collected by filtration, dissolved in 20 mL of toluene, concentrated to about 5 mL, then dropped into 500 mL of methanol and reprecipitated. The precipitate was collected by filtration, dissolved in 100 mL of toluene, washed twice with 100 mL of 3N-HCl, and further repeatedly washed with ultrapure water until neutral. Subsequently, it was washed twice with 100 mL of ammonia water and washed with ultrapure water until neutrality. The toluene solution was concentrated and dropped into 500 mL of methanol for reprecipitation treatment. The precipitate was collected by filtration to obtain 0.167 g of polymer (recovery rate 70%).
In addition, since the polymer obtained here did not melt | dissolve in THF, molecular weight was not able to be measured by gel permeation chromatography (GPC).

<Synthesis Example 10: Synthesis of 3,6-dichlorocarbazole>

Argon-substituted Schlenk was charged with 0.836 g (5.0 mmol) of carbazole and 1.34 g (10.0 mmol) of N-chlorosuccinimide and stirred in 10 mL of DMF for 12 hours. Water was added and extracted with ether, and the ether layer was dried over anhydrous sodium sulfate. Filtration, concentration, and isolation by column chromatography (developing solvent: hexane / dichloromethane = 3/1) gave 0.848 g (3.59 mmol) of the desired product (yield 72%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 8.09 (br, 1H), δ 7.98 (s, 2H), δ 7.41-7.34 (m, 4H).

<Synthesis Example 11: Synthesis of N- (4-triphenylamine) -3,6-dichlorocarbazole>

0.708 g (3.0 mmol) 3,6-dichlorocarbazole, 0.973 g (3.0 mmol) 4-bromotriphenylamine, catalytic amount of copper iodide, 1.91 g (9. 0 mmol) potassium phosphate, 0.0343 g (0.3 mmol) CHDA, and 10 mL 1,4-dioxane were added and the vessel was sealed and stirred at 115 ° C. for 48 hours. 200 mL of water was added to the reaction solution, extraction was performed 3 times with 200 mL of ether, and the ether layer was dried over anhydrous sodium sulfate. After removing the desiccant by filtration and concentrating, the product was isolated and produced by column chromatography (developing solvent hexane) to obtain 1.20 g (2.50 mmol) of the desired product as a white powder (yield 83%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 8.04 (s, 2H), δ 7.40-7.20 (m, 16H), δ 7.08 (t, 2H).

<Synthesis Example 12: Synthesis of N- [4- {N, N-bis (4'-bromophenyl) amino} phenyl] -3,6-dichlorocarbazole>

1.20 g (2.5 mmol) of 3,6-dichlorocarbazole-N-triphenylamine was added to Schlenk, and the container was purged with argon, and 25 mL of DMF was added thereto and dissolved. After cooling the vessel with an ice bath, a solution of 0.890 g (5.0 mmol) of NBS in DMF was added. When the ice bath was removed and the mixture was stirred at room temperature, a precipitate was formed in about 4 hours. After stirring for 16 hours, 100 mL of water was added, and the mixture was extracted 4 times with 100 mL of chloroform. The chloroform layer was concentrated to about 100 mL and washed 3 times with 100 mL of water. The chloroform layer was dried over anhydrous sodium sulfate, filtered to remove sodium sulfate, and the chloroform layer was concentrated. The solid was washed with hexane to obtain 1.10 g (1.72 mmol) of the desired product as a white powder (yield 69%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 8.04 (s, 2H), δ 7.45-7.22 (m, 12H), δ 7.04 (d, 4H).

<Synthesis Example 13: Synthesis of N- [4- {N, N-bis (4 ′-( 4 -pentenyl) phenyl) amino} phenyl] -3,6-dichlorocarbazole>

Argon-substituted Schlenk was charged with 1.0 g (41.1 mmol) of magnesium, and a solution of 5.0 g (33.6 mmol) of 5 -bromo- 1 -pentene dissolved in 30 mL of THF was refluxed with heat of reaction. It was dripped little by little at speed. Thereafter, the mixture was further refluxed for 1 hour to prepare a Grignard reagent. Argon-substituted Schlenk was newly prepared, and 1.00 g (1.5 mmol) of N- [4- {N, N-bis (4′-bromophenyl) amino} phenyl] -3,6-dichlorocarbazole was prepared there. A catalytic amount of PdCl ₂ (dppf) and 5 mL of THF were added and stirred. Thereto was added 5.0 mL (5.0 mmol) of the Grignard reagent prepared earlier, and the mixture was stirred at 80 ° C. for 20 hours. The ether layer was dried over sodium sulfate, filtered, concentrated, and then isolated by column chromatography (developing solvent: hexane / dichloromethane = 4/1) to obtain 0.879 g (1.38 mmol) of the desired product (yield). 92%).
In addition, the structure of the obtained target object was confirmed with the raw material used and the ¹ H-NMR spectrum data shown below.
¹ H-NMR (400 MHz. CDCl ₃ ): δ 8.03 (s, 2H), δ 7.42-7.10 (m, 12H), δ 5.91-5.80 (m, 2H), δ 5.07- 4.98 (m, 4H), δ 2.61 (t, 4H), δ 2.17-2.10 (m, 4H), δ 1.78-1.70 (m, 4H), δ 1.55 (s, 4H).

Synthesis Example 14 Synthesis of 2,7-Linked Poly-N- [4- {N, N-bis (4 ′-( 5 -hexenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole>

Argon-substituted Schlenk was charged with 0.198 g (0.72 mmol) of bis (1,5-cyclooctadiene) nickel (0) and 0.112 g (0.72 mmol) of 2,2′-bipyridyl in an argon stream. After adding 1.2 mL of DMF, the mixture was stirred at room temperature for 30 minutes. There, 0.202 g (0.30 mmol) of N- [4- {N, N-bis (4 ′-( 5 -hexenyl) phenyl) amino} phenyl] -3,6-dimethyl-2,7-dichloro A solution of carbazole dissolved in 3.0 mL of DMF was added, and the vessel was sealed and stirred at 65 ° C. for 72 hours. The reaction solution was added dropwise to a mixed solvent of 500 mL of methanol and 20 mL of concentrated hydrochloric acid and stirred for 24 hours. The precipitate was collected by filtration, dissolved in 20 mL of toluene, concentrated to about 5 mL, then dropped into 500 mL of methanol and reprecipitated. The precipitate was collected by filtration, dissolved in 100 mL of toluene, washed twice with 100 mL of 3N-HCl, and further repeatedly washed with ultrapure water until neutral. Subsequently, it was washed twice with 100 mL of ammonia water and washed with ultrapure water until neutrality. The toluene solution was concentrated and dropped into 500 mL of methanol for reprecipitation treatment. The precipitate was collected by filtration to obtain 0.135 g of polymer (recovery rate 75%).
Furthermore, as a result of measuring the molecular weight of the polymer obtained here by gel permeation chromatography (GPC) using THF as a mobile phase, the weight average molecular weight (Mw) 51,823, number average molecular weight in terms of standard polystyrene. It was (Mn) 12,197 and molecular weight distribution (Mw / Mn) 4.25.

Synthesis Example 15 Synthesis of 2,7-Linked Poly-N- [4- {N, N-bis (4 ′-( 4 -pentenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole>

Argon-substituted Schlenk was charged with 0.33 g (1.20 mmol) of bis (1,5-cyclooctadiene) nickel (0) and 0.19 g (1.20 mmol) of 2,2′-bipyridyl in an argon stream. , 2.0 mL of DMF was added and stirred at room temperature for 30 minutes. There, 0.321 g (0.50 mmol) of N- [4- {N, N-bis (4 ′-( 4 -pentenyl) phenyl) amino} phenyl] -3,6-dimethyl-2,7-dichloro A solution of carbazole dissolved in 5.0 mL of DMF was added, and the vessel was sealed and stirred at 65 ° C. for 72 hours. The reaction solution was added dropwise to a mixed solvent of 500 mL of methanol and 20 mL of concentrated hydrochloric acid and stirred for 24 hours. The precipitate was collected by filtration, dissolved in 20 mL of toluene, concentrated to about 5 mL, then dropped into 500 mL of methanol and reprecipitated. The precipitate was collected by filtration, dissolved in 100 mL of toluene, washed twice with 100 mL of 3N-HCl, and further repeatedly washed with ultrapure water until neutral. Subsequently, it was washed twice with 100 mL of ammonia water and washed with ultrapure water until neutrality. The toluene solution was filtered through a membrane filter having a pore size of 5 μm, and then filtered through a membrane filter having a pore size of 1 μm. Thereafter, the toluene solution was concentrated to about 5 mL and dropped into 500 mL of methanol for reprecipitation treatment. The precipitate was collected by filtration to obtain 0.232 g of polymer (recovery rate 81%).
Furthermore, as a result of measuring the molecular weight of the polymer obtained here by gel permeation chromatography (GPC) using THF as a mobile phase, the weight average molecular weight (Mw) 285,682, the number average molecular weight in terms of standard polystyrene (Mn) 26,224 and molecular weight distribution (Mw / Mn) 10.9.

<Synthesis Example 16: Synthesis of 2,7-bonded poly-N- [4- {N, N-bis (4-isopropylphenyl) amino} phenyl] -3,6-dimethylcarbazole>

Argon-substituted Schlenk was charged with 0.33 g (1.20 mmol) of bis (1,5-cyclooctadiene) nickel (0) and 0.19 g (1.20 mmol) of 2,2′-bipyridyl in an argon stream. , 2.0 mL of DMF was added and stirred at room temperature for 30 minutes. There, 0.296 g (0.50 mmol) of N- [4- {N, N-bis (4′-isopropylphenyl) amino} phenyl] -3,6-dimethyl-2,7-dichlorocarbazole was added. A solution of 0.0 mL of DMF and 4.0 mL of THF was added, the vessel was sealed and stirred at 65 ° C. for 72 hours. The reaction solution was added dropwise to a mixed solvent of 500 mL of methanol and 20 mL of concentrated hydrochloric acid and stirred for 24 hours. The precipitate was collected by filtration, dissolved in 20 mL of toluene, concentrated to about 5 mL, then dropped into 500 mL of methanol and reprecipitated. The precipitate was collected by filtration, dissolved in 100 mL of toluene, washed twice with 100 mL of 3N-HCl, and further repeatedly washed with ultrapure water until neutral. Subsequently, it was washed twice with 100 mL of ammonia water and washed with ultrapure water until neutrality. The toluene solution was filtered through a membrane filter having a pore size of 1 μm, and then the toluene solution was concentrated to about 5 mL and dropped into 500 mL of methanol for reprecipitation treatment. The precipitate was collected by filtration to obtain 0.232 g of polymer (recovery rate 88%).
Furthermore, as a result of measuring the molecular weight of the polymer obtained here by gel permeation chromatography (GPC) using THF as a mobile phase, the weight average molecular weight (Mw) 187,640, the number average molecular weight in terms of standard polystyrene (Mn) 51,254 and molecular weight distribution (Mw / Mn) 3.66.

Hereinafter, effects of the embodiment of the present invention will be described.
In the organic EL elements 11 and 12 according to the embodiment of the present invention, an anode 2, a hole injection layer 3, a light emitting layer 4, and a cathode 5 are laminated in this order on a substrate 1. Since the injection layer 3 is composed of a hole transporting polymer having a polycarbazole skeleton represented by the general formula (1), it is soluble in an organic solvent before crosslinking and insoluble in an organic solvent after crosslinking. Using a hole transporting polymer, an organic EL device having high luminous efficiency and a long device lifetime can be obtained. In particular, the luminous efficiency can be greatly improved.

  Since the organic EL elements 11 and 12 according to the embodiments of the present invention use a hole-transporting polymer that is insoluble in an organic solvent, the light-emitting layer solution prepared by dissolving in an organic solvent is used as the above-described hole-transporting polymer. By applying on the hole injection layer 3 made of molecules, the light emitting layer 4 can be easily laminated on the hole injection layer 3.

  The organic EL elements 11 and 12 according to the embodiment of the present invention are polymerized within a molecule or between molecules by heating a hole transporting polymer precursor having a polycarbazole skeleton represented by the general formula (1). Since the hole injection layer 3 made of a hole transporting polymer formed by crosslinking groups is used, the molecular structure consisting of a carbazole ring and a triphenylamine substituent is maintained, and the hole transporting ability is maintained. And an organic EL device having high hole transportability.

  Since the organic EL elements 11 and 12 according to the embodiments of the present invention have a configuration in which the polymer group of the hole transporting polymer precursor is a vinyl group, the polymer group is heated to crosslink the polymer group within or between the molecules. The hole injection layer 3 made of a hole transporting polymer can be easily formed.

  Since the organic EL elements 11 and 12 according to the embodiments of the present invention have a configuration in which the hole transporting polymer precursor is soluble in an organic solvent, a solution in which the hole transporting polymer precursor is dissolved is spin-coated. The hole injection layer 3 can be formed using a uniform thin film of a hole transporting polymer precursor formed by coating on a substrate using a coating method such as the above. Further, by using a solution dissolved in an organic solvent, the influence of water can be eliminated from the organic EL element, and the life of the organic EL element can be improved.

  The organic EL element 12 according to the embodiment of the present invention has a structure in which another hole injection layer is inserted between the hole injection layer and the anode. The hole injection efficiency can be improved, and the light emission efficiency of the organic EL element can be improved.

Since the organic EL display which is an embodiment of the present invention has a structure in which the organic EL elements 11 and 12 are formed in a matrix on the substrate, it is soluble in an organic solvent before crosslinking, and is dissolved in an organic solvent after crosslinking. Organic EL elements with high luminous efficiency and long element lifetime can be formed for each pixel using a hole-transporting polymer that becomes insoluble, so it is driven at low voltage, has high luminous efficiency, and has a long element lifetime. The organic EL display with low power consumption and high reliability can be obtained. Further, since it can be formed from a solution by a wet method, the area can be easily increased. Therefore, it can be applied not only to display devices such as backlights and flat panel displays, but also to lighting devices and the like.
Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples.

Example 1
First, using the synthesis method described above, the 2,7-linked poly-N- [4- {N, N-bis (4 ′-(5-hexenyl) phenyl) amino represented by the general formula (25) is represented. } Phenyl] -3,6-dimethylcarbazole was synthesized.
Next, 2,7-bonded poly-N- [4- {N, N-bis (4 ′-(5-hexenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole was added to a toluene solution in an amount of about 1 wt. % To prepare a hole injection layer solution.
Next, in a glove box having oxygen and nitrogen of 1 ppm or less, the hole injection layer solution was applied by spin coating on a glass substrate on which an ITO film having a thickness of 150 nm was patterned, and the thickness was about 30 nm. A hole injection layer was formed. Next, this thin film sample was placed on a hot plate and dried at about 80 ° C. for 1 hour, and then the temperature of the hot plate was further set to 200 ° C. for heating for 1 hour. When toluene was dropped into the hole injection layer thin film after the crosslinking reaction and the solubility was examined, almost no dissolution was observed.

Next, a luminescent fluorene polymer represented by the following general formula (28) was dissolved in a dichloroethane solution so as to be about 1% by weight to prepare a light emitting layer solution.
Next, the light emitting layer solution was applied onto the hole injection layer thin film by a spin coating method to form a light emitting layer having a thickness of about 100 nm, and then dried at 100 ° C. for 1 hour.

Finally, as an electrode, first, a 10 nm-thick Ca film was formed by a vacuum vapor deposition method, and then a 100 nm-thick Al film was continuously formed to prepare a polymer EL device.
From this polymer EL device, uniform green light emission was observed by applying a voltage. The luminous efficiency (external quantum efficiency) was 0.1%.

(Example 2-1)
First, in the same manner as in Example 1, using the synthesis method described above, the 2,7-position bonded poly-N- [4- {N, N-bis (4′-) represented by the above general formula (25) was used. (5-Hexenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole was synthesized, and its hole injection layer solution (toluene solution, about 1% by weight) was prepared.
Next, a hole injection material PEDOT: PSS (baytorn) is applied on the same glass substrate as in Example 1 by spin coating, and then heated and dried at 200 ° C. to form a first hole injection layer having a thickness of 30 nm. Formed.

  Next, the hole injection layer solution was applied onto the PEDOT: PSS layer while controlling the rotation speed by a spin coating method, thereby forming a second hole injection layer having a thickness of about 190 nm. Next, the thin film sample was placed on a hot plate and dried sufficiently at about 60 ° C. Then, the temperature of the hot plate was further set to 200 ° C. and heating for the crosslinking reaction was performed for about 1 hour. When toluene was dropped into the hole injection layer thin film after the crosslinking reaction and the solubility was examined, almost no dissolution was observed.

Next, the green light emitting fluorene polymer represented by the general formula (28) was dissolved in a dichloroethane solution so as to be about 1% by weight to prepare a light emitting layer solution.
Next, the light emitting layer solution was applied onto the hole injection layer thin film by a spin coating method to form a light emitting layer having a thickness of about 100 nm, and then dried at 100 ° C. for 1 hour.

Finally, as an electrode, first, a 10 nm-thick Ca film was formed by vacuum vapor deposition, and then a 150-nm continuous film was formed of Al to prepare a polymer EL device.
From this polymer EL device, uniform green light emission was observed by applying a voltage. The luminous efficiency (external quantum efficiency) was 0.2%.

(Example 2-2)
A polymer EL device was produced in the same manner as in Example 2-1, except that the rotation speed was controlled by the spin coating method and the second hole injection layer was formed to a thickness of 215 nm.

(Example 2-3)
A polymer EL device was produced in the same manner as in Example 2-1, except that the number of rotations was controlled by a spin coating method and the film thickness of the second hole injection layer was 220 nm.

(Comparative Example 1)
A polymer EL device was produced in the same manner as in Example 2-1, except that the second hole injection layer was not formed.
Table 1 shows the characteristics of the organic EL elements of Example 2-1 to Example 2-3 and Comparative Example 1.

(Example 3)
First, in the same manner as in Example 1, using the synthesis method described above, the 2,7-position bonded poly-N- [4- {N, N-bis (4′-) represented by the above general formula (25) was used. (5-Hexenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole was synthesized, and its hole injection layer solution (toluene solution, about 1% by weight) was prepared.
Next, a hole injection material PEDOT: PSS (baytorn) is applied on the same glass substrate as in Example 1 by spin coating, and then heated and dried at 200 ° C. to form a first hole injection layer having a thickness of 30 nm. Formed.

  Next, the hole injection layer solution was applied onto the PEDOT: PSS layer while controlling the rotation speed by a spin coating method, thereby forming a second hole injection layer having a thickness of about 190 nm. Next, the thin film sample was placed on a hot plate and dried sufficiently at about 60 ° C. Then, the temperature of the hot plate was further set to 200 ° C. and heating for the crosslinking reaction was performed for about 1 hour. When toluene was dropped into the hole injection layer thin film after the crosslinking reaction and the solubility was examined, almost no dissolution was observed.

Next, a phenylcarbazole dimer linked with adamantane represented by the following general formula (29) is used as a host material, and a blue light-emitting iridium complex represented by the following general formula (30) is used as a guest material in a dichloroethane solution to emit light. The layer solution was prepared.
Next, the light emitting layer solution was applied onto the hole injection layer thin film by a spin coating method to form a light emitting layer having a thickness of about 100 nm, and then dried at 100 ° C. for 1 hour.

Next, after forming TPBI represented by the following general formula (31) to a thickness of 10 nm by a vacuum evaporation method to form a hole blocking layer (hole blocking layer), Alq ₃ (quinolinol aluminum represented by the following general formula (32): The complex) was deposited to a thickness of 30 nm by a vacuum deposition method to form an electron injection layer.

Finally, as an electrode, first, a 10 nm-thick Ca film was formed by vacuum vapor deposition, and then a 150-nm continuous film was formed of Al to prepare a polymer EL device.
From this polymer EL element, uniform blue light emission was observed by applying a voltage. The luminous efficiency (external quantum efficiency) was 7.5%.

Example 4
An organic EL display was prototyped with the configuration of the polymer EL element of Example 2-1.
First, an ITO film serving as an anode was formed on a 10 cm square glass substrate by an RF sputtering method, and then etched to form 128 stripes to form an anode wire (anode 5).
In addition, as shown in Example 2-1, the first hole injection layer (hole injection layer 31) made of PEDOT: PSS, the 2,7-position bonded poly-N shown in the general formula (25). A second hole injection layer (hole injection layer 32) comprising-[4- {N, N-bis (4 '-(5-hexenyl) phenyl) amino} phenyl] -3,6-dimethylcarbazole, and the above The light emitting layer 4 made of a green fluorene polymer represented by the general formula (28) was formed by a spin coating method.
Finally, a cathode made of Ca and Al is formed by vacuum deposition using a stainless steel shadow mask so as to form 72 stripes orthogonal to the ITO line, and a cathode line (cathode 2) did. FIG. 4 is an enlarged cross-sectional view of this organic EL display.
When a video signal having a duty ratio of 1/128 and a frame frequency of 60 Hz was sent to the cathode line (cathode 2) and the anode line (anode 5), a moving image could be confirmed.

  The present invention relates to an organic EL element. In particular, the present invention relates to a high-efficiency and long-life organic EL element using an organic compound, and has a wide range of applications to information displays such as next-generation high-definition televisions, lighting fixtures, and light sources.

It is a cross-sectional schematic diagram explaining an example of the organic EL element which is embodiment of this invention. It is a cross-sectional schematic diagram explaining an example of the organic EL element which is embodiment of this invention. It is a conceptual diagram explaining an example of the crosslinking reaction of the hole transportable polymer used for the organic EL element which is embodiment of this invention. It is an organic EL display expanded sectional view which is an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Anode, 3 ... Hole injection layer, 4 ... Light emitting layer, 5 ... Cathode, 11, 12 ... Organic EL element, 21 ... Polymer chain, 22 ... Polymerization group, 22a ... Cross-linking part, 23 ... Polymer chain, 31 ... first hole injection layer, 32 ... second hole injection layer.

Claims (9)

Hole transporting polymer compound for organic EL device you characterized by having a poly carbazole skeleton represented by the following general formula (5).

[In Formula (5), n is an integer of 1-1000, R is a substituent, and is either a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group. , Ar ₁ and Ar ₂ each independently represent an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group.
X is a substituent having a polymerizable functional group that can be cross-linked by light or heat regardless of the presence or absence of a catalyst, and includes a vinyl group, a trifluorovinyl group, an acrylic group, a methacryl group, and an oxetane group. Or an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic hydrocarbon group, or an optionally substituted aromatic heterocyclic group having an epoxy group, etc. A and b each independently represent an integer of 1 to 5. ] Hole transporting polymer compound for an organic EL device according to claim 1, characterized in that it comprises a poly carbazole skeleton represented by the following general formula (6).

[In Formula (6), n is an integer of 1-1000, R is a substituent, and is either a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group. .
X is a substituent having a polymerizable functional group that can be cross-linked by light or heat regardless of the presence or absence of a catalyst, and includes a vinyl group, a trifluorovinyl group, an acrylic group, a methacryl group, and an oxetane group. Or an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic hydrocarbon group, or an optionally substituted aromatic heterocyclic group having an epoxy group, etc. A and b each independently represent an integer of 1 to 5. ] On the substrate, an anode, a hole injection layer, a light emitting layer, and a cathode are laminated in this order,
3. The organic EL device , wherein the hole injection layer is made of a hole transporting polymer compound for an organic EL device according to claim 1 or 2 . The organic EL device according to claim 3 , wherein the hole injection layer made of the hole transporting polymer compound is insoluble in an organic solvent. Wherein the hole injection layer made of a hole transporting polymer compound, and heating the hole-transporting polymer compound precursor for the organic EL device according to claim 1 or claim 2, intramolecular or the organic EL device according to claim 3 or claim 4, characterized in that it is formed by crosslinking polymerization group between. The organic EL device according to claim 5 , wherein the polymerizable group is a vinyl group. The organic EL device according to claim 5 or 6, wherein the hole transporting polymer compound precursor is soluble in an organic solvent. The organic EL device according to any one of claims 3-7, characterized in that to insert another hole injection layer between the anode and the hole injection layer. An organic EL display comprising the organic EL element according to any one of claims 3 to 8 formed in a matrix on a substrate.

Images