JP2008305995A - Organic electric field light emitting element and display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electric field light emitting element which has high brightness, is excellent in stability and durability, capable of enlarging an area and easy to manufacture, and has little defect in manufacture and little degradation with time in element performance. <P>SOLUTION: The organic electric field light emitting element is characterized in that an organic compound layer consists of two or more layers at least including a buffer layer and a light-emitting layer, at least one layer of the organic compound layer contains one kind of charge transport polyurethane, and the buffer layer is provided in contact with an positive electrode and contains a bridged compound formed using at least one kind of a charge injection material having a silicon substituent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent element and a display device.

  An electroluminescent element is a self-luminous all-solid-state element, has high visibility and is resistant to impact, and thus is widely expected to be applied.

  Research on electroluminescent devices using organic compounds started with a single crystal such as anthracene, but in the case of a single crystal, a film thickness of about 1 mm and a driving voltage of 100 V or more were necessary. For this reason, attempts have been made to reduce the thickness by vapor deposition (see Non-Patent Document 1).

In recent years, in a function-separated electroluminescent device in which a thin film of a hole-transporting organic low-molecular compound and a fluorescent organic low-molecular compound having an electron-transporting capability are sequentially stacked by a vacuum deposition method, 1000 cd / which m ² or more high luminance can be obtained it has been reported (see non-Patent Document 2). Since this research report, research and development of stacked electroluminescent devices have been actively conducted.

  These stacked devices are injected from the electrode through a charge transport layer made of a charge transporting organic compound into a light emitting layer made of a fluorescent organic compound while maintaining the carrier balance of holes and electrons, High-luminance light emission is realized by recombination of the confined holes and electrons.

  By the way, a starburst amine capable of obtaining a stable amorphous glass state is used as a hole transport material (for example, see Non-Patent Document 3 etc.), or a polymer in which triphenylamine is introduced into a side chain of polyphosphazene ( A non-patent document 4) electroluminescent device has been reported.

  In addition, research and development of an organic electroluminescent device having a single layer structure that can shorten the process has been advanced, and a device using a conductive polymer such as poly (p-phenylene vinylene) (for example, see Non-Patent Document 5) A device in which an electron transporting material and a fluorescent dye are mixed in hole transporting polyvinyl carbazole (see Non-Patent Document 6) has been proposed.

  Furthermore, from the viewpoint of manufacturing methods, wet application methods have been studied from the viewpoints of manufacturing simplification, workability, large area, cost, etc., and it has been reported that elements can also be obtained by casting methods ( (See Non-Patent Documents 7 and 8).

  In addition, display devices using organic electroluminescent elements are more suitable for miniaturization and thinning than other display devices such as liquid crystals, and are expected to be used for portable devices driven by internal power supplies. Yes. In order to realize such a portable device, it is important that it can be driven for a long time with less power consumption.

On the other hand, the basic layer structure of the organic electroluminescent element is that a hole transport layer (or a light-emitting layer having charge transport ability) is provided on a transparent electrode (anode) made of ITO, and other layers are provided as necessary. It has the structure provided. Here, as a method for dealing with the above-described applications and further energy saving, a buffer layer is provided between the transparent electrode and the hole transport layer (or the light-emitting layer having charge transport ability), and holes are formed. A method for improving the efficiency of injecting charges (holes) into the transport layer (or the light-emitting layer having charge transport ability) is known, whereby the drive voltage can be lowered. As typical materials constituting this buffer layer, for example, PEDOT (polyethylene dioxythiophene), starburst amine, CuPc (copper phthalocyanine) and the like are known.
Thin Solid Films, Vol. 94, 171 (1982) Applied Physics Letter, Vol. 51,913 (1987) Proceedings of the 40th Joint Conference on Applied Physics 30a-SZK-14 (1993) 42nd Polymer Symposium Proceedings 20J21 (1993) Nature, Vol. 357, 477 (1992) Proceedings of the 38th Joint Conference on Applied Physics 31pg-12 (1991) Proceedings of the 50th Japan Society of Applied Physics, 29p-ZP-5 (1989) Proceedings of the 51st Japan Society of Applied Physics, 28a-PB-7 (1990)

  It is an object of the present invention to have high brightness, excellent stability and durability, large area, easy manufacturing, less generation of manufacturing defects, and small deterioration of device performance over time. An organic electroluminescence device and a display device are provided.

The above problem is solved by the following means. That is, the present invention
The invention according to claim 1
A pair of an anode and a cathode, at least one of which is transparent or translucent, and a buffer layer and an organic compound layer sandwiched between electrodes of the anode and the cathode,
The organic compound layer is composed of two or more layers including at least a buffer layer and a light emitting layer,
At least one of the organic compound layers includes at least one kind of charge transporting polyurethane represented by the following general formulas (I-1) and (I-2),
The buffer layer is provided in contact with the anode, and includes a cross-linking compound formed using at least one kind of charge injection material having a substituted silicon group represented by the following general formula (III):
This is an organic electroluminescent element characterized by the above.

(In the general formulas (I-1) and (I-2), A represents at least one selected from the structures represented by the following general formulas (II-1) and (II-2), and R represents a hydrogen atom. Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched chain having 2 to 10 carbon atoms. Represents a hydrocarbon, Y represents a divalent diisocyanate residue or a divalent amine residue, Z represents a divalent alcohol residue or a divalent bischloroformate residue, and m represents 0 or 1 , P represents an integer of 5 to 5000. The residue shown here refers to a portion excluding the reactive group of the linking compound.)

(In the general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and k represents Represents 0 or 1)

（一般式（ＩＩＩ）中、Ｒ_１は水素、アルキル基、又は置換もしくは未置換のアリール基を示す。Ｑは加水分解性基を示す。ａは１乃至３の整数を示す。）

(In general formula (III), R ₁ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. A represents an integer of 1 to 3.)

The invention according to claim 2
2. The organic electroluminescent element according to claim 1, wherein the charge injection material is at least one of aromatic amine compounds represented by the following general formulas (IV-1) to (IV-4): is there.

(In the general formulas (IV-1) to (IV-4), Ar represents a substituted or unsubstituted monovalent aromatic group, and Ra represents at least one of the substituted silicon groups represented by the general formula (III). And m and l represent 0 or 1, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms.)

The invention according to claim 3
The organic compound layer is constituted by laminating at least a buffer layer, a light emitting layer, and an electron transport layer in this order from the anode side,
At least one of the light emitting layer and the electron transport layer contains at least one charge transporting polyurethane represented by the general formulas (I-1) and (I-2),
The organic electroluminescent element according to claim 1, wherein:

The invention according to claim 4
The organic electroluminescent element according to claim 3, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane.

The invention according to claim 5
The organic compound layer is configured by laminating at least a buffer layer, a hole transport layer, a light emitting layer, and an electron transport layer in this order from the anode side,
At least one of the hole transport layer, the light emitting layer and the electron transport layer contains at least one kind of charge transporting polyurethane represented by the general formulas (I-1) and (I-2).
The organic electroluminescent element according to claim 1, wherein:

The invention according to claim 6
6. The organic electroluminescent element according to claim 5, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane.

The invention according to claim 7 provides:
The organic compound layer is configured by laminating at least a buffer layer, a hole transport layer, and a light emitting layer in this order from the anode side,
At least one layer of the hole transport layer and the light emitting layer contains at least one kind of charge transport polyurethane represented by the general formulas (I-1) and (I-2),
The organic electroluminescent element according to claim 1, wherein:

The invention according to claim 8 provides:
The organic electroluminescent element according to claim 7, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane.

The invention according to claim 9 is:
The organic compound layer is configured by laminating at least a buffer layer and a light emitting layer having charge transporting ability in this order,
2. The organic electric field according to claim 1, wherein the light emitting layer having the charge transporting capability contains at least one charge transporting polyurethane represented by the general formulas (I-1) and (I-2). It is a light emitting element.

The invention according to claim 10 is:
The organic electroluminescent device according to claim 9, wherein the light emitting layer having the charge transporting capability contains a charge transporting material other than the charge transporting polyurethane.

The invention according to claim 11 is:
An organic electroluminescent device arranged in a matrix, and a driving means for driving the organic electroluminescent device,
The organic electroluminescent element has a pair of an anode and a cathode, at least one of which is transparent or translucent, and an organic compound layer sandwiched between electrodes of the anode and the cathode,
The organic compound layer is composed of two or more layers including at least a buffer layer and a light emitting layer,
At least one of the organic compound layers includes at least one kind of charge transporting polyurethane represented by the following general formulas (I-1) and (I-2),
The buffer layer is provided in contact with the anode, and includes a cross-linking compound formed using at least one kind of charge injection material having a substituted silicon group represented by the following general formula (III):
This is a display device.

(In the general formulas (I-1) and (I-2), A represents at least one selected from the structures represented by the following general formulas (II-1) and (II-2), and R represents a hydrogen atom. Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched chain having 2 to 10 carbon atoms. Represents a hydrocarbon, Y represents a divalent diisocyanate residue or a divalent amine residue, Z represents a divalent alcohol residue or a divalent bischloroformate residue, and m represents 0 or 1 , P represents an integer of 5 to 5000. The residue shown here refers to a portion excluding the reactive group of the linking compound.)

(In the general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and k represents Represents 0 or 1)

(In general formula (III), R ₁ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. A represents an integer of 1 to 3.)

  According to the present invention, it has high brightness, excellent stability and durability, can have a large area, is easy to manufacture, has fewer manufacturing defects, and is less susceptible to deterioration in device performance over time. There is an effect that an organic electroluminescence element can be provided.

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

The organic electroluminescent element according to the present embodiment is
A pair of an anode and a cathode, at least one of which is transparent or translucent (here, transparent or translucent means a visible light transmittance of 50% or more; the same shall apply hereinafter); A buffer layer and an organic compound layer sandwiched between electrodes of the cathode,
The organic compound layer is composed of two or more layers including at least a buffer layer and a light emitting layer,
At least one of the organic compound layers includes at least one kind of charge transporting polyurethane represented by the following general formulas (I-1) and (I-2),
The buffer layer is provided in contact with the anode, and includes a cross-linking compound formed using at least one kind of charge injection material having a substituted silicon group represented by the following general formula (III):
It is characterized by that.

  The organic electroluminescence device according to the present embodiment has the above-described configuration, has high luminance, is excellent in stability and durability, can be increased in area, is easy to manufacture, and further has manufacturing defects. Is less likely to occur, and deterioration of the device performance over time is reduced. This is due to the results of the following examination.

  First, when an organic electroluminescent device provided with a buffer layer was produced, the inventors studied diligently about the occurrence of various defects in production and the cause of deterioration of device performance over time. Then, on the surface of the buffer layer formed on the anode, a hole transport layer or a light emitting layer having a charge transport capability (hereinafter referred to as a buffer layer directly or via another layer) using a polymer charge transport material. In some cases, the indirectly formed layer may be abbreviated as “adjacent layer”).

  As a result, the charge transporting polymer to be used is a vinyl skeleton (for example, PTPDMA (see Polymer Journal, Vol. 52, 216 (1995)) or a polycarbonate skeleton (for example, Et-TPAPEK (43th Applied Physics)). In the case of the academic related joint lecture proceedings collection 27a-SY-19, pp. 1126 (1996)), the adhesion between the buffer layer and the adjacent layer becomes insufficient, and a peeling defect is generated. It was confirmed that holes may be generated or agglomeration may occur, which may be caused by poor conformity at the interface between the buffer layer and the adjacent layer, or the flexibility of the polymer constituting the adjacent layer. There may be a lack.

  Therefore, from the viewpoint of preventing defects in the film formation, the charge transporting polymer used for forming the adjacent layer may be a material having a highly flexible molecular structure or the above-described flexibility. Even if the material has a low molecular structure, by reducing the size of the molecule itself (decreasing the molecular weight), the flexibility of the molecule can be improved and the rearrangement between molecules in the adjacent layer can be facilitated. I thought that it was possible to respond.

  In addition, the cause of the deterioration of the device performance over time was also investigated. As a result, when the charge transporting polymer used is a vinyl skeleton or a polycarbonate skeleton, as described above, the driving voltage increases with time to increase the power consumption, and further, the light emission characteristics themselves deteriorate. It turns out that there is a case.

  When this cause was investigated, the low molecular component (for example, a starburst amine, CuPc (copper phthalocyanine), or a counter ion of an ionic substance used in combination with PEDOT (polyethylene dioxythiophene)) contained in the buffer layer was found. It was found that the original function of the adjacent layer can no longer be exhibited by bleeding to the adjacent layer with time due to Joule heat or electric field generated when an electric field is applied to the element. In addition, the occurrence of bleed is that the low-molecular component in the buffer layer easily penetrates into the adjacent layer formed using the vinyl-based or polycarbonate-based charge transporting polymer, in other words, in the adjacent layer. This means that the gap between the charge transporting polymers is large or easily formed.

Therefore, in order to suppress bleed, it was considered important to form a dense and highly heat-resistant adjacent layer so that bleeding of the low molecular component into the adjacent layer can be prevented. In this case, gaps between molecules that promote bleeding of low molecular components can be filled without gaps when the adjacent layer is formed, and relative movement between molecules occurs in the adjacent layer once formed by heat. In order to prevent bleeding, it is important not to generate gaps between molecules.

  Therefore, from the viewpoint of suppressing bleeding, the charge transporting polymer that forms the adjacent layer can be easily formed into a film having excellent uniformity due to high molecular weight and narrow molecular weight distribution, and a dense secondary layer. It is required to form a structure.

  In order to drastically suppress bleeding, it is also conceivable to use a material that does not contain a low-molecular component that causes bleeding as a charge injection material used for the buffer layer or a component used in combination therewith.

  In addition, the charge transporting polymer needs to have a certain number of hopping sites responsible for charge transfer in the molecule in order to ensure charge mobility that affects the important light emission characteristics of the organic electroluminescent device. There is. That is, in other words, a molecular size (molecular weight) of a certain degree or more is necessarily required.

  Therefore, when obtaining an organic electroluminescent device provided with a buffer layer, in addition to securing the basic characteristics of light emission characteristics, considering the manufacturability and practicality that can withstand long-term use, the formation of adjacent layers As a charge transporting polymer used in the case of using a material that causes bleeding as a buffer layer, in addition to forming a dense film having excellent uniformity, it has only a sufficient charge mobility. In other words, it was considered important to use a material having adhesion to the buffer layer.

In this respect, the charge transporting polyurethane has the following characteristics.
(1) The urethane bond that connects the functional sites is a strong bond and resistant to deformation.
(2) Since the main chain type has a polar group at the binding site, the ratio of functional sites in the polymer is large, so the effect on charge transport is small compared to the side chain type. Furthermore, the influence of a polar group can be further suppressed by interposing a spacer.
(3) The adhesion between adjacent layers (especially the buffer layer) is excellent due to the polar group of the ester bond.
(4) Since the polymer synthesis is performed under mild conditions, the reaction conditions are easy to control. Therefore, it is possible to synthesize a polymer that can be easily increased in molecular weight and has a relatively uniform molecular weight distribution.
From the above points, it is preferable to use polyurethane having a functional site incorporated in the main chain as the charge transporting polymer.

  Further, in order to drastically suppress bleed, it is considered necessary to form the buffer layer using a component that basically does not require the use of a low molecular component that causes bleed. It is conceivable to use a material that forms a network structure (network) by a strong bond rather than being formed in a state where the injection material contains low molecules.

As a material for forming a network structure (network), a three-dimensional crosslinkable material can be mentioned. As a specific example taken into the charge injection material, for example,
(A) A charge transporting polyurethane having a specific repeating structure and having a hydroxyl group or a carboxyl group at the end, or a polycarbonate or the like is crosslinked using a crosslinking agent having a trifunctional or higher functional isocyanate group or epoxy group in one molecule. (See Japanese Laid-Open Patent Publication No. 8-176293, Japanese Laid-Open Patent Publication No. 8-208820, Japanese Laid-Open Patent Publication No. 8-253568, Japanese Laid-Open Patent Publication No. 9-110974)
(B) A type in which a charge transfer agent having a thermal or photo-curing functional group at the terminal is cross-linked (refer to JP 2000-147804 A, JP 2000-147813 A, etc.)
(C) A type in which a charge transport material having oxetane is photocrosslinked (see Macromol. Rapid Commun., 20, pp224-228 (1999)).
(D) A type in which a charge transport material having an alkoxysilyl group at the terminal is crosslinked by heating (Adv. Mater., Vol. 11, No. 2, pp 107-112 (1999), Adv. Mater., Vol. 11, No. .9, pp 730-734 (1999), JP-A-9-124665, JP-A-11-38656, etc.)
And the like.

  In this regard, the buffer layer formed by the three-dimensional crosslinking treatment using the charge injection material having the substituted silicon group has a substituted silicon group represented by the general formula (III) described later, thereby causing a crosslinking reaction with each other. It is possible to form a three-dimensional-Si-O-Si-bond, that is, an effective inorganic glassy network (network), and at the same time, it has excellent adhesion to a substrate mainly composed of an inorganic material. That is, it is considered good from the viewpoint of improving the characteristics of the organic electroluminescent device because it forms a strong bond by three-dimensional crosslinking and has excellent adhesion to an anode mainly composed of an inorganic material. It is done. In addition, when a charge injection material represented by the general formulas (IV-1) to (IV-4) described later is used, an aromatic amine structural unit is formed and introduced into the three-dimensional crosslinked structure thereby, and electron accepting properties are obtained. Unlike the case where an electron-accepting material is mixed as a concomitant component, it is not necessary to improve the conductivity by utilizing the effect of doping by using the material together. Bleed to the compound layer can be eliminated.

  That is, by using the buffer layer, the charge injection material does not bleed into the adjacent layer and has excellent adhesion to the anode, and at the same time, the adjacent organic layer is formed using the charge transporting polyurethane as an organic EL device. Not only can the required sufficient charge mobility be ensured, but also there are few defects such as pinholes and aggregation, and the adhesiveness with the buffer layer is excellent. As a result, a long-life and high-performance organic EL device can be constructed.

  In the element manufacturing process, by using a polymer compound for all the materials constituting the organic compound layer, all the organic compound layer can be formed by a wet coating method. Although extremely advantageous in terms of area, cost, etc., the charge transport polyurethane can exhibit stable device characteristics regardless of the type of light emitting material used as the light emitting layer.

  As a result, the organic EL device according to the present embodiment has high luminance, excellent stability and durability, can have a large area, and can be easily manufactured, and further has fewer defects in manufacturing. In addition, deterioration of the device performance with time is reduced.

  Hereinafter, the charge transporting ester represented by the general formulas (I-1) and (I-2) will be described.

Charge-transporting polyurethane is easier to synthesize than other types of polymers, and the molecular weight and molecular weight distribution are easy to control. In addition to the above, it is a material capable of forming a dense and uniform film.
In addition, since charge transport polyurethane is easier to synthesize than various types of polymers, it is a material that easily suppresses deterioration of electrical characteristics because impurities are less mixed during synthesis.

  Further, as will be described later, the charge transporting polyurethane can be provided with either a hole transporting function or an electron transporting function by appropriately selecting its molecular structure. For this reason, it can be used for any layer such as a hole transport layer, a light emitting layer, a charge transport layer, etc.

  Particularly preferred as the charge transporting polyurethane is a polyurethane having a hole transporting property (hole transporting polyurethane).

  However, in general formula (I-1) and (I-2), A represents at least 1 sort (s) selected from the structure shown by the following general formula (II-1) and (II-2), and R is hydrogen. Represents an atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched chain having 2 to 10 carbon atoms Y represents a divalent diisocyanate residue or a divalent amine residue, Z represents a divalent alcohol residue or a divalent bischloroformate residue, m represents 0 or 1 And p represents an integer of 5 to 5000. The residue shown here refers to a portion excluding the reactive group of the linking compound.

  In general formula (I-1) or (I-2), A represents at least one selected from the structures represented by the following general formulas (II-1) and (II-2). Two or more types of structures A may be included.

  First, the structures represented by the following general formulas (II-1) and (II-2) will be described in detail.

  In the general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, k Represents 0 or 1.

In general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group.
Specifically, Ar is a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon having 2 to 10 aromatic atoms, a substituted or unsubstituted aromatic group having 1 to 2 aromatic atoms. A substituted or unsubstituted monovalent aromatic group containing a valent condensed ring aromatic hydrocarbon, a substituted or unsubstituted monovalent aromatic heterocyclic ring, or at least one aromatic heterocyclic ring.

  Here, in general formulas (II-1) and (II-2), the number of aromatic rings constituting the polynuclear aromatic hydrocarbon and condensed ring aromatic hydrocarbon selected as the structure representing Ar is not particularly limited. The aromatic ring number is preferably 2 to 5, and the condensed ring aromatic hydrocarbon is preferably a fully condensed ring aromatic hydrocarbon. In addition, the said polynuclear aromatic hydrocarbon and condensed ring aromatic hydrocarbon specifically mean the polycyclic aromatic defined below in this Embodiment.

  That is, the “polynuclear aromatic hydrocarbon” is a hydrocarbon compound in which two or more aromatic rings composed of carbon and hydrogen are present, and these aromatic rings are bonded by a carbon-carbon single bond. Represents. Specific examples include biphenyl and terphenyl.

  The “fused ring aromatic hydrocarbon” means that two or more aromatic rings composed of carbon and hydrogen are present, and these aromatic rings are bonded to each other in a pair of two or more carbon atoms. Represents a hydrocarbon compound sharing Specific examples include naphthalene, anthracene, phenanthrene, fluorene and the like.

  The “aromatic heterocycle” represents an aromatic ring containing an element other than carbon and hydrogen. Nr = 5 and / or 6 is desirably used as the number of atoms (Nr) constituting the ring skeleton. The type and number of elements (heterogeneous elements) other than C constituting the ring skeleton are not particularly limited. For example, S, N, O, and the like are preferably used, and two or more types and / or are included in the ring skeleton. Two or more different atoms may be contained. In particular, as a heterocyclic ring having a 5-membered ring structure, thiophene, thiofin and furan, or a heterocyclic ring obtained by further substituting the carbons at the 3- and 4-positions with nitrogen, pyrrole, or carbons at the 3- and 4-positions thereof with nitrogen Is preferably used, and pyridine is preferably used as the heterocyclic ring having a 6-membered ring structure.

  The “aromatic group containing an aromatic heterocyclic ring” represents a linking group containing at least one kind of the aromatic heterocyclic ring in the atomic group constituting the skeleton. These may be either all composed of conjugated systems or at least partially composed of non-conjugated systems, but all composed of conjugated systems in terms of charge transportability and luminous efficiency. Is desirable.

  As a substituent of a phenyl group, a polynuclear aromatic hydrocarbon, a condensed ring aromatic hydrocarbon, an aromatic heterocycle, or an aromatic group containing an aromatic heterocycle, a hydrogen atom, an alkyl group, an alkoxy group, a phenoxy group, An aryl group, an aralkyl group, a substituted amino group, a halogen atom and the like can be mentioned.

  The alkyl group is preferably one having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The alkoxyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. As the aryl group, those having 6 to 20 carbon atoms are desirable, and examples thereof include a phenyl group and a toluyl group. The aralkyl group is preferably one having 7 to 20 carbon atoms, and examples thereof include a benzyl group and a phenethyl group. Examples of the substituent of the substituted amino group include an alkyl group, an aryl group, an aralkyl group, and the like, and specific examples are as described above.

  In general formulas (II-1) and (II-2), X represents a substituted or unsubstituted divalent aromatic group. Specifically, X is a substituted or unsubstituted phenylene group, a substituted or unsubstituted divalent polynuclear aromatic hydrocarbon having 2 to 10 aromatics, or a substituted or unsubstituted aromatic number 2 to 10 A divalent condensed ring aromatic hydrocarbon, a substituted or unsubstituted divalent aromatic heterocyclic ring, or a substituted or unsubstituted divalent aromatic group containing at least one aromatic heterocyclic ring.

  Here, “polynuclear aromatic hydrocarbon”, “fused ring aromatic hydrocarbon”, “aromatic heterocycle”, and “aromatic group containing an aromatic heterocycle” are as described above.

  In general formulas (II-1) and (II-2), k represents 0 or 1.

  Next, the charge transporting polyurethanes represented by the general formulas (I-1) and (I-2) will be described in detail.

  In general formula (I-1) or (I-2), R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

  The alkyl group is preferably one having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. As the aryl group, those having 6 to 20 carbon atoms are preferable, and examples thereof include a phenyl group and toluyl group. As the aralkyl group, those having 7 to 20 carbon atoms are preferable, such as benzyl group and phenethyl group. Is mentioned. In addition, examples of the substituent of the substituted aryl group and the substituted aralkyl group include a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, and a halogen atom.

  In the general formulas (I-1) and (I-2), T is a divalent linear hydrocarbon group having 1 to 6 carbon atoms or a divalent branched hydrocarbon group having 2 to 10 carbon atoms. And preferably selected from a divalent linear hydrocarbon group having 2 to 6 carbon atoms and a divalent branched hydrocarbon group having 3 to 7 carbon atoms. The specific structure of T is shown below.

  In general formula (I-1) or (I-2), Y represents a divalent diisocyanate residue or a divalent amine residue, and Z represents a divalent alcohol residue or a divalent bischloroformate residue. Represents. Specific examples of Y and Z include groups selected from the following formulas (1) to (7).

In the formulas (1) to (7), R ₁₁ and R ₁₂ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, a substituted group Or an unsubstituted aralkyl group or a halogen atom, a, b and c each represent an integer of 1 to 10, d and e each represent an integer of 0, 1 or 2, and f represents 0 Or it means 1 and V represents the group selected from following formula (8) thru | or (18).

  In the formulas (8) to (18), g represents an integer of 1 to 10, and h represents an integer of 0 to 10, respectively.

  In the general formula (I-1) or (I-2), m represents 0 or 1, and p representing the degree of polymerization is in the range of 5 to 5,000, preferably in the range of 10 to 1,000. is there.

The weight average molecular weight _Mw of the charge transporting polyurethane is preferably in the range of 5,000 to 1,000,000, and more preferably in the range of 10,000 to 300,000.

The weight average molecular weight Mw can be measured by the following method.
For the measurement of the weight average molecular weight, first, a 1.0 mass% THF (tetrahydrofuran) solution of a charge transporting polyurethane was prepared, and a differential refractive index detector (RI, manufactured by TOSOH, trade name: UV-8020) was used. This was performed by gel permeation chromatography (GPC) using styrene polymer as a standard sample.

In the general formulas (I-1) and (I-2) and the general formulas (II-1) and (II-2) described above, it is provided with basic physical properties capable of satisfying synthesis ease and device characteristics. In general formulas (I-1) and (I-2), R represents a methyl group or an ethyl group, Y represents a divalent diisocyanate residue or a divalent amine residue, and Z represents a divalent alcohol. Represents a residue or a divalent bischloroformate residue, m represents 1, p represents an integer of 10 to 1,000, T represents a methylene group or a dimethylene group,
In the general formulas (II-1) and (II-2) represented by A, Ar represents phenyl, biphenyl, naphthalene, or 9,9′-dimethylfluorene (as the substituent of the aromatic ring, a methyl group or an ethyl group). , An isopropyl group, a tert-butyl group, and a methoxy group are desirable.), X represents the following formulas (19) to (20).

It is preferable that k represents 1.

  Here, specific examples of the charge transporting polyurethanes represented by the general formulas (I-1) and (I-2) include those disclosed in, for example, JP-A Nos. 2002-117882 and 2002-117993.

  Next, a method for synthesizing the charge transporting polyurethane will be described. For the charge transporting polyurethane, charge transporting monomers represented by the following structural formulas (V-1) to (V-4) are described in, for example, the 4th edition Experimental Chemistry Course Vol. 28 (Maruzen, 1992). It can synthesize | combine by making it superpose | polymerize by a well-known method.

  In Structural Formulas (V-1) to (V-4), A, T, and m are the same as A, T, and m in General Formulas (I-1) and (I-2).

  That is, the charge transporting polyurethane represented by the general formula (I-1) and the general formula (I-2) can be synthesized, for example, as follows.

  When the dihydric alcohol represented by the general formula (V-1) is used as the charge transporting monomer, 1 equivalent of the charge transporting monomer and 1 equivalent of the “diisocyanate represented by OCN—Y—NCO” are mixed. By performing the polyaddition reaction, the charge transporting polyurethane represented by the general formula (I-1) can be synthesized.

  On the other hand, when the diisocyanate represented by the general formula (V-2) is used as the charge transporting monomer, 1 equivalent of the charge transporting monomer and 1 equivalent of the “divalent alcohol represented by HO—Z—OH” are used. By mixing and performing a polyaddition reaction, the charge transporting polyurethane represented by the above general formula (I-2) can be synthesized.

  Examples of the catalyst used in the polyaddition reaction include organometallic compounds such as dibutyltin dilaurate (II), dibutyltin diacetate (II), and lead naphthenate. These catalysts can be used.

  When an aromatic diisocyanate is used as the diisocyanate, a tertiary amine such as triethylenediamine can be used as the catalyst. The organometallic compound and the tertiary amine may be used as a mixture.

  The amount of the catalyst is desirably 1 / 10,000 parts by weight or more and 1/10 parts by weight or less, more desirably 1 / 1,000 parts by weight or more and 1/50 parts by weight or less based on 1 part by weight of the charge transporting monomer. It is used in the range.

The solvent is a raw material (charge transporting monomer represented by general formula (V-1) and “diisocyanate represented by OCN-Y-NCO”) or a general formula (V-2) used for polyaddition reaction. Although it is not particularly limited as long as it dissolves a charge transporting monomer and “dihydric alcohol represented by HO—Z—OH”), it causes a hydrogen bond with a less polar solvent or alcohol in terms of reactivity. It is desirable to use no solvent. Desirable solvents include, for example, toluene, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like.
The amount of the solvent to be used is desirably 1 to 100 parts by weight, more desirably 2 to 50 parts by weight, with respect to 1 part by weight of the charge transporting monomer.
The reaction temperature is not particularly limited and can be set arbitrarily.

  After completion of the reaction, the reaction solution is dropped as it is into a poor solvent in which the charge transport polyurethane is difficult to dissolve (specifically, alcohols such as methanol and ethanol, acetone, etc.), and the charge transport polyurethane is deposited. After separation, the substrate is thoroughly washed with water or an organic solvent and dried.

Furthermore, if necessary, a reprecipitation process (specifically, a process of dissolving in an organic solvent and dropping in a poor solvent to precipitate a charge transporting polyurethane) may be repeated.
The reprecipitation treatment is preferably carried out with efficient stirring with a mechanical stirrer or the like.

  The solvent for dissolving the charge transporting polyurethane in the reprecipitation treatment is preferably 1 part by weight or more and 100 parts by weight or less, more preferably 2 parts by weight or more and 50 parts by weight or less with respect to 1 part by weight of the charge transporting polyurethane. Used in a range. The poor solvent is preferably used in an amount of 1 to 1,000 parts by weight, more preferably 10 to 500 parts by weight, based on 1 part by weight of the charge transporting polyurethane.

When the bischloroformate represented by the general formula (V-3) is used as the charge transporting monomer, 1 equivalent of the charge transporting monomer and 1 equivalent of the “diamine represented by H ₂ N—Y—NH ₂ ” And a polycondensation reaction are carried out to synthesize a charge transporting polyurethane represented by the general formula (I-1).

  On the other hand, when the diamine represented by the general formula (V-4) is used as the charge transporting monomer, 1 equivalent of the charge transporting monomer and 1 equivalent of the “bischloroformate represented by ClCOO-Z—OCOCl” Are mixed and a polycondensation reaction is performed to synthesize a charge transporting polyurethane represented by the above general formula (I-2).

As the solvent used for the polycondensation reaction, for example, methylene chloride, dichloroethane, trichloroethane, tetrahydrofuran (THF), toluene, chlorobenzene, 1-chloronaphthalene and the like are desirably used. The solvent is preferably used in the range of 1 to 100 parts by weight, more preferably 2 to 50 parts by weight with respect to 1 part by weight of the charge transporting monomer.
The reaction temperature is not particularly limited and can be set arbitrarily.

  After completion of the polymerization reaction, purification is performed by reprecipitation as described above.

In the case where the bischloroformate represented by the general formula (V-3) is used as the charge transporting monomer, the compound having a high basicity as the “diamine represented by H ₂ N—Y—NH ₂ ” When is used, an interfacial polymerization method can also be used.

  Specifically, for example, the above diamines are added to water, 1 equivalent of an acid (for example, terephthalic acid chloride, etc.) is added to 1 equivalent of the diamine and dissolved, and then 1 equivalent of the diamine is stirred vigorously. Polymerization can also be carried out by adding 1 equivalent of the “charge-transporting monomer represented by the general formula (V-3)”.

The amount of water used is preferably in the range of 1 to 1,000 parts by weight, more preferably 10 to 500 parts by weight with respect to 1 part by weight of the diamine.
As the solvent for dissolving the charge transporting monomer, for example, methylene chloride, dichloroethane, trichloroethane, toluene, chlorobenzene, 1-chloronaphthalene and the like are desirably used.
The reaction temperature is not particularly limited and can be set arbitrarily.

  In order to accelerate the interfacial polymerization reaction, it is desirable to use a phase transfer catalyst such as an ammonium salt or a sulfonium salt. The phase transfer catalyst is preferably used in the range of 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight with respect to 1 part by weight of the charge transporting monomer.

  Hereinafter, the charge injection material having a substituted silicon group represented by the general formula (III) will be described.

  In the charge injection material having a substituted silicon group represented by the general formula (III), for example, since the substituted silicon group includes a hydrolyzable group, a cross-linking reaction occurs with each other, and a three-dimensional —Si—O—Si— bond, That is, it is a three-dimensional crosslinkable material that forms an inorganic glassy network (network).

However, in the general formula (III), R ₁ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. a represents an integer of 1 to 3.

In general formula (III), the alkyl group represented by R ₁ is preferably, for example, one having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

In general formula (III), the aryl group represented by R ₁ preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a toluyl group. Examples of the substituent for the aryl group include an alkyl group, an alkoxy group, a phenoxy group, an aryl group, an aralkyl group, a substituted amino group, and a halogen atom.

  Here, the alkyl group as the substituent of the aryl group is preferably one having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The alkoxyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. As the aryl group, those having 6 to 20 carbon atoms are desirable, and examples thereof include a phenyl group and a toluyl group. The aralkyl group is preferably one having 7 to 20 carbon atoms, and examples thereof include a benzyl group and a phenethyl group. Examples of the substituent of the substituted amino group include an alkyl group, an aryl group, an aralkyl group, and the like, and specific examples are as described above (see general formulas (I-1) and (I-2)).

  Examples of the hydrolyzable group represented by Q include an alkoxy group, a methylethylketoxime group, a diethylamino group, an acetoxy group, a propenoxy group, and a halogen. As the alkoxy group, those having 1 to 10 carbon atoms are desirable, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group.

  Specific examples of the charge injection material having a substituted silicon group represented by the general formula (III) include aromatic compounds such as tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, and arylhydrazone derivatives. Among these, aromatic amine compounds represented by the following general formulas (IV-1) to (IV-4) are preferable.

  In the general formulas (IV-1) to (IV-4), Ar represents a substituted or unsubstituted monovalent aromatic group, and Ra represents at least a substituted silicon group represented by the general formula (III). 1 represents m, l represents 0 or 1, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms.

  In general formulas (IV-1) to (IV-4), Ar represents a substituted or unsubstituted monovalent aromatic group. Specifically, Ar is a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon having 2 to 10 aromatic atoms, a substituted or unsubstituted aromatic group having 1 to 2 aromatic atoms. A substituted or unsubstituted monovalent aromatic group containing a valent condensed ring aromatic hydrocarbon, a substituted or unsubstituted monovalent aromatic heterocyclic ring, or at least one aromatic heterocyclic ring.

  Here, “polynuclear aromatic hydrocarbon”, “fused ring aromatic hydrocarbon”, “aromatic heterocycle”, and “aromatic group containing an aromatic heterocycle” are as described above.

  In the general formulas (IV-1) to (IV-4), l and m represent 0 or 1, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms, or 2 to 10 carbon atoms. A divalent branched hydrocarbon group, preferably a divalent linear hydrocarbon group having 2 to 6 carbon atoms and a divalent branched hydrocarbon group having 3 to 7 carbon atoms Selected. The specific structure of T is the same as described above.

  The aromatic amine compounds represented by the general formulas (IV-1) to (IV-4) described above have a substituted silicon group represented by the general formula (III) via a covalent bond at the terminal, It is a three-dimensional crosslinkable charge transport material capable of forming a three-dimensional crosslinked product having an aromatic amine structural unit.

  In addition, the aromatic amine structure in general formula (IV-1) and (IV-2) makes the part shown by X of the structure shown by general formula (II-1) into biphenyl or terphenyl, The aromatic amine structures in the general formulas (IV-3) and (IV-4) are those in which the part represented by X in the structure represented by the general formula (II-2) is biphenyl or terphenyl.

Here, in the aromatic amine compounds represented by the general formulas (IV-1) to (IV-4), Ar represents phenyl, biphenyl, naphthalene, 9,9′-dimethylfluorene, and (as a substituent of the aromatic ring) Is preferably a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, or a methoxy group.)
m represents 0, l represents 1,
T represents a methylene group or a dimethylene group;
Ra is _{-Si (OCH} 3) 3, representing the -SiH _{(OCH 3) 2,}
Is preferred.

  Specific examples of the aromatic amine compounds represented by the general formulas (IV-1) to (IV-2) include the following.

  Specific examples of the aromatic amine compounds represented by the general formulas (IV-3) to (IV-4) include the following.

Next, the layer configuration of the organic electroluminescent element according to the present embodiment will be described in detail.
The organic electroluminescent device according to the present embodiment includes two or more layers including a pair of anodes and cathodes, at least one of which is transparent or translucent, and a light emitting layer and a buffer layer sandwiched between the pair of electrodes. And an organic compound layer. The buffer layer includes one or more charge injection materials and is provided in contact with the anode. Further, at least one of the organic compound layers contains at least one kind of the charge transporting polyurethane.

  In addition, the film thickness of the organic compound layer located closest to the anode among the organic compound layers containing the charge transporting polyurethane is in the range of 20 nm to 100 nm (desirably, 20 nm to 80 nm, more Desirably, it is within 20 nm to 50 nm. This organic compound layer is a light-emitting layer having charge transport capability when the organic compound layer is a single layer type, and preferably a hole transport layer when the organic compound layer is a function separation type (stacked type).

  In the organic electroluminescent device according to the present embodiment, when the organic compound layer is composed of only the buffer layer and the light emitting layer, this light emitting layer means a light emitting layer having charge transporting ability, and this charge transporting ability A light-emitting layer having the charge transporting polyurethane is contained.

  When the organic compound layer has one or more other layers in addition to the buffer layer and the light emitting layer (in the case of a function separation type of three or more layers), the other layers excluding the buffer layer and the light emitting layer are , A carrier transport layer, that is, a hole transport layer, an electron transport layer, or a layer composed of a hole transport layer and an electron transport layer, and the charge transporting polyurethane is included in at least one of these layers.

  Specifically, the organic compound layer includes, for example, a configuration including at least a buffer layer, a light emitting layer, and an electron transport layer, a configuration including at least a buffer layer, a hole transport layer, a light emitting layer, and an electron transport layer, or at least a buffer layer. In addition, the structure may include a hole transport layer and a light emitting layer. In this case, it is desirable that the charge transporting polyurethane is contained in at least one of these layers (hole transporting layer, electron transporting layer, light emitting layer). Preferably, the charge transporting polyurethane is used as the hole transporting material. Is desirable. In particular, it is preferable that at least the light emitting layer and the hole transport layer in contact with the buffer layer contain the charge transporting polyurethane.

  In the case where the buffer layer and the light emitting layer are included, the buffer layer is provided between the anode and the light emitting layer. In the case of a configuration including at least a buffer layer, a light emitting layer, and an electron transport layer, the buffer layer is provided between the anode and the light emitting layer. In the case of a configuration including at least a buffer layer, a hole transport layer, a light emitting layer, and an electron transport layer, the buffer layer is provided between the anode and the hole transport layer. In the case of a configuration including at least a buffer layer, a hole transport layer, and a light emitting layer, the buffer layer is provided between the anode and the hole transport layer.

  Here, in the configuration including the buffer layer, the light emitting layer, and the electron transport layer, both manufacturability and light emission efficiency can be achieved in comparison with other layer configurations. This is because the number of layers is smaller than that of a layer structure in which all functions are separated, but in general, the electron injection efficiency, which is lower in mobility than holes, is compensated for and the charge in the light emitting layer is balanced. Conceivable.

  In the configuration including the buffer layer, the hole transport layer, the light emitting layer, and the electron transport layer, the light emitting efficiency is excellent and low voltage driving is possible as compared with the devices having other layer configurations. This is presumably because the functional separation results in the highest charge injection efficiency compared to other layer configurations, and charges can be recombined in the light emitting layer.

  In the configuration including the buffer layer, the hole transport layer, and the light emitting layer, both ease of manufacture and durability can be achieved compared to other configurations. This is thought to be because the number of layers is smaller than that of the layer structure in which all functions are separated, but the efficiency of hole injection into the light emitting layer is improved and excessive electron injection is suppressed in the light emitting layer.

  In the case of being composed of only the buffer layer and the light emitting layer, the element can be easily increased in area and manufactured as compared with other layer configurations. This is because the number of layers is small and can be produced by wet coating, for example.

  Further, in the organic electroluminescent element according to the present embodiment, the light emitting layer may contain a charge transporting material (a hole transporting material other than the charge transporting polyurethane, an electron transporting material). Details of such a charge transporting material will be described later.

Hereinafter, the organic electroluminescence device according to the present embodiment will be described in more detail with reference to the drawings, but is not limited thereto.
1 to 4 are schematic cross-sectional views for explaining the layer structure of the organic electroluminescent element according to this embodiment. In the case of FIGS. 1, 2, and 3, there are three organic compound layers. Or it is an example in the case of 4 layer structure, and in the case of FIG. 4, the example in case an organic compound layer is 2 layer structure is shown. In FIG. 1 to FIG. 4, components having similar functions are described with the same reference numerals.

The organic electroluminescent element 10 shown in FIG. 1 is formed by sequentially laminating a transparent electrode 2, a buffer layer 3, a light emitting layer 5, an electron transport layer 6 and a back electrode 8 on a transparent insulator substrate 1.
An organic electroluminescent device 10 shown in FIG. 2 is formed by sequentially laminating a transparent electrode 2, a buffer layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6 and a back electrode 8 on a transparent insulator substrate 1. Become.
The organic electroluminescent element 10 shown in FIG. 3 is formed by sequentially laminating a transparent electrode 2, a buffer layer 3, a hole transport layer 4, a light emitting layer 5, and a back electrode 8 on a transparent insulator substrate 1.
An organic electroluminescent element 10 shown in FIG. 4 is formed by sequentially laminating a transparent electrode 2, a buffer layer 3, a light emitting layer 7 having a charge transport capability, and a back electrode 8 on a transparent insulator substrate 1.

  1 to 4, the transparent electrode 2 means an anode, and the back electrode 8 means a cathode. Each will be described in detail below.

  In addition, depending on the structure, the layer containing the charge transporting polyurethane can act as both the light emitting layer 5 and the electron transporting layer 6 in the case of the layer configuration of the organic electroluminescent element 10 shown in FIG. In the case of the layer configuration of the organic electroluminescent device 10 shown in FIG. 2, any of the hole transport layer 4, the light emitting layer 5, and the electron transport layer 6 can act, and the organic electroluminescent device 10 shown in FIG. In the case of the layer configuration, both can act as the hole transport layer 4 and the light emitting layer 5, and in the case of the layer configuration of the organic electroluminescent element 10 shown in FIG. can do. In particular, it can preferably act as a hole transport material.

  The transparent insulator substrate 1 is preferably transparent in order to extract emitted light, and glass, plastic film, etc. are used, but not limited thereto. Further, the transparent electrode 2 is preferably transparent so as to extract emitted light in the same manner as the transparent insulator substrate, and preferably has a high work function (ionization potential) in order to inject holes, indium tin oxide (ITO), An oxide film such as tin oxide (NESA), indium oxide, and zinc oxide, and deposited or sputtered gold, platinum, palladium, and the like are used, but not limited thereto.

  The buffer layer 3 is formed in contact with the anode (transparent electrode 2) and contains one or more kinds of charge injection materials. Then, the charge injection material is formed using the charge injection material having the substituted silicon group. Specifically, for example, the buffer layer 3 includes a three-dimensional cross-linked product formed of the charge injection material having the substituted silicon group.

  The charge injection material is a layer provided in contact with the surface of the buffer layer 3 opposite to the side on which the anode is provided (that is, the light emitting layer 5 in FIG. 1, the hole transport layer 4 in FIGS. 4, the ionization potential is preferably 5.4 eV or less, more preferably 5.1 eV or less, in order to improve the charge injection property into the light-emitting layer 7) having charge transport ability. The number of buffer layers 3 is not particularly limited, but is preferably one or two layers, and more preferably one layer.

  As the material constituting the buffer layer 3, in addition to the above-mentioned agent, other materials having no charge injection property such as a binder resin can be used as necessary.

  The electron transport layer 6 may be formed of the above charge transporting polyurethane alone having a function (electron transport ability) according to the purpose, but for the purpose of further improving the electrical characteristics, the electron mobility. In order to control this, an electron transport material other than the charge transporting polyurethane may be mixed and dispersed in the range of 1% by weight to 50% by weight.

  Preferred examples of such an electron transport material include oxadiazole derivatives, triazole derivatives, phenylquinoxaline derivatives, nitro-substituted fluorenone derivatives, diphenoquinone derivatives, thiopyrandioxide derivatives, fluorenylidenemethane derivatives, and the like. Preferable specific examples include the following compounds (VII-1) to (VII-3), but are not limited thereto. In addition, when forming the electron transport layer 6 without using the said charge transportable polyurethane, the electron transport layer 6 is formed using these electron transport materials.

  The hole transport layer 4 may be formed of a charge transport polyurethane alone having a function (hole transport ability) according to the purpose, but other than the charge transport polyurethane in order to adjust the hole mobility. The hole transport material may be mixed and dispersed in the range of 1 wt% to 50 wt%.

  Examples of the hole transporting material include tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, arylhydrazone derivatives, porphyrin compounds, and the like, and particularly preferable specific examples include the following compounds (VIII-1) to (VIII- 7), and a tetraphenylenediamine derivative is preferable because of its good compatibility with the charge transporting polyurethane. Moreover, you may mix and use with other general purpose resin etc. When the hole transport layer 4 is formed without using the charge transport polyether, the hole transport layer 4 is formed using these hole transport materials, but the hole transport layer 4 is Since it is in contact with the buffer layer 3, it is preferably formed using at least one charge transporting polyether. In compound (VIII-7), n (integer value) is preferably in the range of 10 to 100,000, and more preferably in the range of 1000 to 50,000.

  For the light-emitting layer 5, a compound showing a high fluorescence quantum yield in a solid state as compared with other types is used as a light-emitting material. In the case where the light emitting material is an organic low molecule, it is a condition that a good thin film can be formed by applying and drying a solution or dispersion containing a low molecular weight and a binder resin. In the case of a polymer, it is a condition that a good thin film can be formed by applying and drying a solution or dispersion containing itself.

  Preferably, in the case of small organic molecules, chelate-type organometallic complexes, polynuclear or condensed aromatic ring compounds, perylene derivatives, coumarin derivatives, styrylarylene derivatives, silole derivatives, oxazole derivatives, oxathiazole derivatives, oxadiazole derivatives, etc. In the case of a polymer, examples include polyparaphenylene derivatives, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyacetylene derivatives, polyfluorene derivatives, and the like. As preferred specific examples, the following compounds (IX-1) to (IX-17) are used, but are not limited thereto.

  In the following structural formulas (IX-13) to (IX-17), Ar and X are monovalent having the same structure as Ar and X shown in the general formulas (II-1) and (II-2). A group or a divalent group, n and x are integers of 1 or more, and y is 0 or 1.

  In addition, for the purpose of improving the durability of the organic electroluminescent device 10 or improving the light emission efficiency, the light emitting material may be doped with a dye compound different from the light emitting material as a guest material. When the light emitting layer is formed by vacuum deposition, doping is performed by co-evaporation, and when the light emitting layer is formed by applying and drying a solution or dispersion, doping is performed by mixing in the solution or dispersion. The doping ratio of the dye compound in the light emitting layer is about 0.001 to 40% by weight, preferably about 0.01 to 10% by weight.

  As the coloring compound used for this doping, an organic compound that has good compatibility with the light emitting material and does not prevent the formation of a good thin film of the light emitting layer is used, preferably a DCM derivative, a quinacridone derivative, a rubrene derivative, a porphyrin. System compounds and the like. As preferred specific examples, the following compounds (X-1) to (X-4) are used, but are not limited thereto.

  The light emitting layer 5 may be formed of the light emitting material alone, but for the purpose of further improving the electrical characteristics and the light emitting characteristics, the charge transporting polyurethane is added to the light emitting material in an amount of 1% by weight to 50%. It may be formed by mixing and dispersing in the range of wt%, or may be formed by mixing and dispersing in the light emitting polymer a charge transport material other than the charge transporting polyurethane in the range of 1 wt% to 50 wt%.

  Further, when the charge transporting polymer also has a light emitting property, it may be used as a light emitting material. In this case, the charge is added to the light emitting material for the purpose of further improving the electrical property and the light emitting property. A charge transport material other than the transportable polyurethane may be mixed and dispersed in the range of 1% by weight to 50% by weight.

  The light-emitting layer 7 having a charge transporting capability is, for example, the light-emitting material (IX-1) as a light-emitting material in the charge-transporting polyurethane having a function (hole transporting capability or electron transporting capability) according to the purpose. ) To (IX-17) are preferably contained in a material in which 50% by weight or less is dispersed. In this case, 10 wt% to 50 wt% of a charge transport material other than the charge transport polyurethane may be dispersed in order to adjust the balance between holes and electrons injected into the organic electroluminescent device 10.

  As the charge transport material, when adjusting the electron mobility, the electron transport material preferably includes an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyrandioxide derivative, a fluorenylidenemethane derivative, and the like. . Preferable specific examples include the compounds (VII-1) to (VII-3). In addition, it is desirable to use an organic compound that does not exhibit a strong electron interaction with the charge transporting polyurethane, and more desirably, the following compound (XI) is used, but is not limited thereto.

  Similarly, when adjusting the hole mobility, particularly preferable examples of the hole transporting material include tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, arylhydrazone derivatives, porphyrin compounds, and the like. Examples of the compound include compounds (VIII-1) to (VIII-7), and a tetraphenylenediamine derivative is preferable because of its good compatibility with the charge transporting polyurethane.

  For the back electrode 8, a metal element that can be vacuum-deposited and has a small work function is used to perform electron injection, but magnesium, aluminum, silver, indium and alloys thereof, lithium fluoride, oxidation, etc. Examples thereof include metal halogen compounds such as lithium and metal oxides.

Further, a protective layer may be provided on the back electrode 7 in order to prevent the element from being deteriorated by moisture or oxygen. Specific materials for the protective layer include metals such as In, Sn, Pb, Au, Cu, Ag, and Al, metal oxides such as MgO, SiO ₂ , and TiO ₂ , polyethylene resin, polyurea resin, and polyimide resin. Resin. For forming the protective layer, a vacuum deposition method, a sputtering method, a plasma polymerization method, a CVD method, a coating method, or the like can be applied.

  The organic electroluminescent element 10 shown in FIGS. 1 to 4 is manufactured by the following procedure. First, the buffer layer 3 is formed on the transparent electrode 2 previously formed on the transparent insulator substrate 1. Specifically, for example, the material constituting the buffer layer 3 is dissolved or dispersed in a solvent so as to have a predetermined concentration, and a spin coating method, a dip method, or the like is used on the transparent electrode 2 using the obtained coating solution. To form a film. Then, if necessary, the buffer layer 3 is formed by curing by heating or the like.

  As a material constituting the buffer layer 3, for example, in addition to the charge injection material, as described above, a binder resin and a coating property improver that do not cause hole trapping can be used as necessary. For various purposes, other silane coupling agents, aluminum coupling agents, titanate coupling agents, and the like can also be added.

  Next, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, and a light emitting layer 7 having a charge transporting capability are sequentially formed on the buffer layer 3 in accordance with the layer configuration of each organic electroluminescent element 10. .

  Further, the hole transport layer 4, the light emitting layer 5, the electron transport layer 6 and the light emitting layer 7 having charge transporting ability are formed by using the materials constituting these layers by vacuum deposition as described above. Or it forms by forming into a film using a spin coating method, a dip method, etc. using the coating liquid obtained by melt | dissolving or disperse | distributing this material in an organic solvent.

  When a polymer is used as the charge transport material and the light emitting material, each layer is preferably formed by a film forming method using a coating solution, but may be formed by film forming using an ink jet method.

  Further, the thickness of the formed buffer layer is preferably 1 nm to 200 nm, and particularly preferably in the range of 10 to 150 nm.

The film thicknesses of the hole transport layer 4, the light emitting layer 5, and the electron transport layer 6 are each preferably 20 nm or more and 100 nm or less, and more preferably in the range of 30 to 80 nm. Further, the thickness of the light emitting layer 7 having charge transporting ability is desirably 20 nm or more and 200 nm or less, and more desirably 30 nm or more and 200 nm or less.
However, when the organic compound layer in contact with the buffer layer 3 (the hole transport layer 4, the light emitting layer 5, or the light emitting layer 7 having charge transport capability) contains a charge transporting polyether, the organic layer in contact with the buffer layer 3 is used. The film thickness of the compound layer is desirably 20 nm or more and 100 nm or less, and more desirably 30 nm or more and 60 nm or less.

  When the above materials (the charge transporting polyurethane, the light emitting material, etc.) are dispersed in an organic solvent to prepare a coating solution, the dispersion state of the materials in the coating solution may be a molecular dispersion state or a particle dispersion state. . In the case of a film forming method using a coating solution, it is necessary to use a common solvent for each of the above materials as a dispersion solvent in order to obtain a molecular dispersion state. It is necessary to select in consideration of solubility and solubility. In order to disperse into particles, a ball mill, a sand mill, a paint shaker, an attritor, a homogenizer, an ultrasonic method, or the like can be used.

  Finally, a back electrode 8 is formed on the light-emitting layer 5, the electron transport layer 6 or the light-emitting layer 7 having charge transport ability by a vacuum deposition method, thereby obtaining the organic electroluminescent device 10 shown in FIGS. be able to.

-Display device-
The display device according to the present embodiment includes the organic electroluminescent element according to the present embodiment and driving means for driving the organic electroluminescent element.
Specifically, for example, as shown in FIGS. 1 to 4, the display device is connected to a pair of electrodes (transparent electrode 2, back electrode 8) of the organic electroluminescent element 10, and a DC voltage is applied between the pair of electrodes. For example, a device provided with a voltage applying device 9 as a driving means may be used.
As a driving method of the organic electroluminescent element 10 using the voltage applying device 9, for example, organic electroluminescence is applied by applying a DC voltage of 4 to 20 V and a current density of 1 to 200 mA / cm ² between a pair of electrodes. The element 10 can emit light.

In addition, the organic electroluminescent element of the present embodiment has been described with respect to the configuration of the minimum unit (one pixel unit). The Of course, the electrode pairs may be arranged in a matrix.
As a driving method of the display device, a conventionally known technique, for example, a plurality of row electrodes and column electrodes are arranged, and the column electrodes are collectively processed according to image information corresponding to each row electrode while scanning the row electrodes. Simple matrix driving for driving, active matrix driving using pixel electrodes arranged for each pixel, or the like can be used.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

―Synthesis of charge transporting polyurethane―
(Synthesis Example 1)
The following compound (XII-1) 2.0 g and chlorobenzene 30 ml were placed in a 50 ml flask and dissolved under stirring in a nitrogen stream. Next, a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was dropped into the flask over 30 minutes, heated to 150 ° C. and stirred for 2 hours. Then, it cooled to room temperature, melt | dissolved in tetrahydrofuran (THF) 50 ml, and filtered the insoluble matter with a 0.2 micrometer polytetrafluoroethylene (PTFE) filter. The reprecipitation treatment in which the filtrate was dropped into 500 ml of methanol while stirring was performed three times to wash and precipitate the polymer.
The obtained polymer was filtered, washed sufficiently with methanol and dried to obtain 1.9 g of charge transporting polyurethane (XII-2).
When the molecular weight distribution of the charge transporting polyurethane (XII-2) was measured by gel permeation chromatography (GPC), the weight average molecular weight Mw = 8.67 × 10 ⁴ (in terms of styrene), and the number average molecular weight Mn And the weight average molecular weight Mw (Mw / Mn) = 1.44.

(Synthesis Example 2)
The following compound (XIII-1) 2.0 g and chlorobenzene 30 ml were placed in a 50 ml flask and dissolved under stirring in a nitrogen stream. Next, a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was dropped into the flask over 30 minutes, heated to 150 ° C. and stirred for 2 hours. Then, it cooled to room temperature, melt | dissolved in tetrahydrofuran (THF) 50 ml, and filtered the insoluble matter with a 0.2 micrometer polytetrafluoroethylene (PTFE) filter. The reprecipitation treatment in which the filtrate was dropped into 500 ml of methanol while stirring was performed three times to wash and precipitate the polymer.
The obtained polymer was filtered, washed thoroughly with methanol and then dried to obtain 1.8 g of a charge transporting polyurethane (XIII-2).
When the molecular weight distribution of the charge transporting polyurethane (XIII-2) was measured by gel permeation chromatography (GPC), the weight average molecular weight Mw = 1.23 × 10 ⁵ (in terms of styrene) and the number average molecular weight Mn And the weight average molecular weight Mw (Mw / Mn) = 2.01.

(Synthesis Example 3)
The following compound (XIV-1) 2.0 g and chlorobenzene 30 ml were placed in a 50 ml flask and dissolved under stirring in a nitrogen stream. Next, a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was dropped into the flask over 30 minutes, heated to 150 ° C. and stirred for 2 hours. Then, it cooled to room temperature, melt | dissolved in tetrahydrofuran (THF) 50 ml, and filtered the insoluble matter with a 0.2 micrometer polytetrafluoroethylene (PTFE) filter. The reprecipitation treatment in which the filtrate was dropped into 500 ml of methanol while stirring was performed three times to wash and precipitate the polymer.
The polymer obtained was filtered, washed thoroughly with methanol and then dried to obtain 1.9 g of charge transporting polyurethane (XIV-2).
When the molecular weight distribution of the charge transporting polyurethane (XIV-2) was measured by gel permeation chromatography (GPC), the weight average molecular weight Mw = 1.17 × 10 ⁵ (in terms of styrene) and the number average molecular weight Mn And the weight average molecular weight Mw (Mw / Mn) = 1.51.

(Synthesis Example 4)
The following compound (XV-1) 2.0 g and chlorobenzene 30 ml were placed in a 50 ml flask and dissolved under stirring in a nitrogen stream. Next, a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was dropped into the flask over 30 minutes, heated to 150 ° C. and stirred for 2 hours. Then, it cooled to room temperature, melt | dissolved in tetrahydrofuran (THF) 50 ml, and filtered the insoluble matter with a 0.2 micrometer polytetrafluoroethylene (PTFE) filter. The reprecipitation treatment in which the filtrate was dropped into 500 ml of methanol while stirring was performed three times to wash and precipitate the polymer.
The obtained polymer was filtered, washed sufficiently with methanol and dried to obtain 1.8 g of a charge transporting polyurethane (XV-2).
When the molecular weight distribution of the charge transporting polyurethane (XV-2) was measured by gel permeation chromatography (GPC), the weight average molecular weight Mw = 1.20 × 10 ⁵ (in terms of styrene) and the number average molecular weight Mn And the weight average molecular weight Mw (Mw / Mn) = 2.2.

(Synthesis Example 5)
The following compound (XVI-1) 2.0 g and chlorobenzene 30 ml were placed in a 50 ml flask and dissolved under stirring in a nitrogen stream. Next, a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was dropped into the flask over 30 minutes, heated to 150 ° C. and stirred for 2 hours. Then, it cooled to room temperature, melt | dissolved in tetrahydrofuran (THF) 50 ml, and filtered the insoluble matter with a 0.2 micrometer polytetrafluoroethylene (PTFE) filter. The reprecipitation treatment in which the filtrate was dropped into 500 ml of methanol while stirring was performed three times to wash and precipitate the polymer.
The obtained polymer was filtered, washed thoroughly with methanol and dried to obtain 1.7 g of a charge transporting polyurethane (XVI-2).
When the molecular weight distribution of the charge transporting polyurethane (XVI-2) was measured by gel permeation chromatography (GPC), the weight average molecular weight Mw = 1.12 × 10 ⁵ (in terms of styrene) and the number average molecular weight Mn And the weight average molecular weight Mw (Mw / Mn) = 1.9.

-Fabrication of organic electroluminescence device-
Next, using the charge transporting polyurethane synthesized as described above, an organic electroluminescence device was produced as follows.

Example 1
As a buffer layer forming solution, 500 mg of a charge injection material having a substituted silicon group (the following structural formula (XIX), ionization potential = 5.0 eV) and 2 mg of hydrochloric acid (1N) were dissolved in 1 ml of butanol to prepare a solution.

  In addition, a substrate (hereinafter abbreviated as “glass substrate with ITO electrode”) on which a 2 mm-wide strip ITO electrode was formed by etching was prepared as a substrate with a transparent electrode.

Next, using the above solution, the glass substrate with an ITO electrode that has been washed and dried is coated on the surface on which the ITO electrode is provided by spin coating, and heated at 120 ° C. for 1 hour to be cured. After sufficiently drying, a buffer layer having a thickness of 10 nm was formed.
Next, as a light-emitting material, a light-emitting polymer [the following compound (XX), polyfluorene-based, Mw≈10 ⁵ ] is 5% by weight, and a hole-transporting material is used for the purpose of further improving electrical characteristics and light-emitting characteristics. A polytetrafluoroethylene (PTFE) filter having a mesh size of 0.1 μm and a chlorobenzene solution in which 1 wt% of the charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] is dissolved together The solution obtained by filtration in (1) was applied on the buffer layer by spin coating to form a light emitting layer having a thickness of 30 nm.

After the formed light emitting layer is sufficiently dried, a dichloroethane solution in which 5% by weight of a charge transporting polyurethane [compound (XIII-2) (Mw = 1.23 × 10 ⁵ )] as an electron transporting material is dissolved is used. After opening and filtering with a 0.1 μm PTFE filter, this solution was applied onto the light emitting layer by a spin coating method to form an electron transport layer having a thickness of 30 nm.
Finally, a Mg—Ag alloy was deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 150 nm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 2)
A buffer layer was formed on the cleaned glass substrate with an ITO electrode in the same manner as in Example 1 using a charge injection material having a substituted silicon group represented by the structural formula (XIX) [ionization potential = 5.0 eV], A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] is dissolved as a pore transporting material is a polytetrafluoroethylene (PTFE) having an opening of 0.1 μm. The solution obtained by filtering with a filter was applied on the buffer layer by spin coating to form a hole transport layer having a thickness of 30 nm.
After sufficiently drying, a chlorobenzene solution in which 5% by weight of a light-emitting polymer [compound (XX), polyfluorene, Mw≈10 ⁵ ] is dissolved as a light-emitting material is filtered through a PTFE filter having an opening of 0.1 μm. The solution obtained in this manner was applied onto the hole transport layer by a spin coating method to form a light emitting layer having a thickness of 50 nm.

Further, a dichloroethane solution in which 5% by weight of a charge transporting polyurethane [compound (XIII-2) (Mw = 1.23 × 10 ⁵ )] as an electron transporting material was dissolved was filtered through a PTFE filter having an opening of 0.1 μm. The obtained solution was applied onto the light emitting layer by a spin coating method to form an electron transport layer having a thickness of 30 nm.
Finally, a Mg—Ag alloy was deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 150 nm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 3)
A buffer layer was formed on the cleaned glass substrate with an ITO electrode in the same manner as in Example 1 using a charge injection material having a substituted silicon group represented by the structural formula (XIX) [ionization potential = 5.0 eV], A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] is dissolved as a pore transporting material is a polytetrafluoroethylene (PTFE) having an opening of 0.1 μm. The solution obtained by filtering with a filter was applied on the buffer layer by spin coating to form a hole transport layer having a thickness of 30 nm.
After sufficiently drying, a chlorobenzene solution in which 5% by weight of a light-emitting polymer [compound (XX), polyfluorene, Mw≈10 ⁵ ] is dissolved as a light-emitting material is filtered through a PTFE filter having an opening of 0.1 μm. The solution obtained in this manner was applied onto the hole transport layer by a spin coating method to form a light emitting layer having a thickness of 50 nm.
Finally, a Mg—Ag alloy was deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 150 nm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

Example 4
A buffer layer was formed on the cleaned glass substrate with an ITO electrode in the same manner as in Example 1 using a charge injection material having a substituted silicon group represented by the structural formula (XIX) [ionization potential = 5.0 eV], Charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] as a hole transporting material: 0.5 part by weight and a light emitting polymer [compound (XX), polyfluorene based as a light emitting material , Mw≈10 ⁵ ]: 0.1 parts by weight, and chlorobenzene solution in which 10% by weight of the mixture is dissolved is filtered through a polytetrafluoroethylene (PTFE) filter having an opening of 0.1 μm to emit light. A solution for layer formation was prepared.

Using this solution, a 50 nm-thick light-emitting layer having a charge transporting capability is formed on the buffer layer by spin coating, and finally a Mg-Ag alloy is vapor-deposited by co-evaporation to obtain a 2 mm width and 150 nm thickness. A thick back electrode was formed to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 5)
As a charge injection material having a substituted silicon group for forming a buffer layer, a material represented by the following structural formula (XXI), [ionization potential = 5.4 eV] is used, and 500 mg of a charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by spin coating, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm, and then the same as in Example 1. An organic EL element was produced.

(Example 6)
As a charge injection material having a substituted silicon group for forming a buffer layer, the material represented by the structural formula (XXI) [ionization potential = 5.4 eV] is used, and 500 mg of a charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by a spin coating method, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm, followed by the same procedure as in Example 2. An organic EL element was produced.

(Example 7)
As a charge injection material having a substituted silicon group for forming a buffer layer, the material represented by the structural formula (XXI) [ionization potential = 5.4 eV] is used, and 500 mg of a charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by spin coating, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm, followed by the same procedure as in Example 3. An organic EL element was produced.

(Example 8)
As a charge injection material having a substituted silicon group containing a hydrolyzable group for forming a buffer layer, the material represented by the structural formula (XXI) [ionization potential = 5.4 eV] is used, and 500 mg of a charge transport material and hydrochloric acid (1N) are used. Except that a solution prepared by dissolving 2 mg in 1 ml of butanol was applied by spin coating, sufficiently dried by heating at 120 ° C. for 1 hour, and then a buffer layer having a thickness of 10 nm was formed. An organic EL device was produced in the same manner as in Example 4.

Example 9
A chlorobenzene solution in which 5% by weight of a luminescent polymer [compound (XXII), polyparaphenylene vinylene (PPV) type, Mw≈10 ⁵ ] is dissolved as a luminescent material is used as a luminescent material, has a mesh size of 0.1 μm. ) An organic EL device was produced in the same manner as in Example 1 except that the solution obtained by filtration through a filter was applied on the buffer layer by spin coating to form a light emitting layer having a thickness of 30 nm.

(Example 10)
Obtained by filtering a chlorobenzene solution in which 5% by weight of a light-emitting polymer [compound (XXII), PPV type, Mw≈10 ⁵ ] is dissolved as a light-emitting material through a polytetrafluoroethylene (PTFE) filter having a mesh size of 0.1 μm. An organic EL device was produced in the same manner as in Example 2 except that the obtained solution was applied onto the hole transport layer by spin coating to form a light emitting layer having a thickness of 30 nm.

(Example 11)
Obtained by filtering a chlorobenzene solution in which 5% by weight of a light-emitting polymer [compound (XXII), PPV type, Mw≈10 ⁵ ] is dissolved as a light-emitting material through a polytetrafluoroethylene (PTFE) filter having a mesh size of 0.1 μm. An organic EL device was produced in the same manner as in Example 3 except that the obtained solution was applied onto the hole transport layer by a spin coating method to form a light emitting layer having a thickness of 30 nm.

(Example 12)
Charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] as a hole transporting material: 0.5 part by weight and a light emitting polymer (XXII), PPV system, Mw as a light emitting material ≒ 10 ⁵ ]: 0.1 part by weight is mixed, and a chlorobenzene solution in which 10% by weight of the mixture is dissolved is filtered through a polytetrafluoroethylene (PTFE) filter having an opening of 0.1 μm to form a light emitting layer. The solution for was prepared.

  Using this solution, an organic EL device was produced in the same manner as in Example 4 except that a light emitting layer having a charge transport ability of 50 nm in thickness was formed on the buffer layer by spin coating.

(Example 13)
As a charge transport material having a substituted silicon group for forming a buffer layer, the material represented by the structural formula (XXI) [ionization potential = 5.4 eV] is used, and 500 mg of the charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by spin coating, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm, followed by the same procedure as in Example 11. An organic EL element was produced.

(Example 14)
A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XIV-2) (Mw = 1.17 × 10 ⁵ )] is dissolved as a hole transporting material is a polytetrafluoroethylene having an opening of 0.1 μm ( An organic EL device was produced in the same manner as in Example 11 except that a solution obtained by filtering with a PTFE filter was applied on the buffer layer by spin coating to form a 30 nm-thick hole transport layer. did.

(Example 15)
A buffer layer was formed on the cleaned glass substrate with an ITO electrode in the same manner as in Example 1 with a charge transport material having a substituted silicon group represented by the structural formula (XXI) [ionization potential = 5.4 eV], A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XII-2) (Mw = 8.67 × 10 ⁴ )] is dissolved as a pore transporting material is a polytetrafluoroethylene (PTFE) having an opening of 0.1 μm. The solution obtained by filtering with a filter was applied on the buffer layer by spin coating to form a hole transport layer having a thickness of 30 nm.
After sufficiently drying, after sufficiently drying, Alq ₃ (compound (IX-1)) purified by sublimation as a luminescent material is put on a tungsten board and deposited by a vacuum deposition method, and a film thickness of 50 nm is formed on the hole transport layer. At this time, the degree of vacuum was 10 ⁻⁵ Torr and the boat temperature was 300 ° C.
Finally, a Mg—Ag alloy was deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 150 nm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 16)
As a charge transport material having a substituted silicon group for forming a buffer layer, the material represented by the structural formula (XXI) [ionization potential = 5.4 eV] is used, and 500 mg of the charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by spin coating, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm. An organic EL element was produced.

(Example 17)
A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XV-2) (Mw = 1.20 × 10 ⁵ )] is dissolved as a hole transporting material is a polytetrafluoroethylene having an opening of 0.1 μm ( An organic EL device was produced in the same manner as in Example 11 except that a solution obtained by filtering with a PTFE filter was applied on the buffer layer by spin coating to form a 30 nm-thick hole transport layer. did.

(Example 18)
A chlorobenzene solution in which 5% by weight of the above charge transporting polyurethane [compound (XVI-2) (Mw = 1.12 × 10 ⁵ )] is dissolved as a hole transporting material is a polytetrafluoroethylene having an opening of 0.1 μm ( An organic EL device was produced in the same manner as in Example 11 except that a solution obtained by filtering with a PTFE filter was applied on the buffer layer by spin coating to form a 30 nm-thick hole transport layer. did.

(Example 19)
As a charge injection material having a substituted silicon group for forming a buffer layer, a material represented by the following structural formula (XXIII) [ionization potential = 5.1 eV] is used, and 500 mg of a charge transport material and 2 mg of hydrochloric acid (1N) are dissolved in 1 ml of butanol. The solution prepared in this manner was applied by spin coating, heated at 120 ° C. for 1 hour and sufficiently dried to form a buffer layer having a thickness of 10 nm, and then the same as in Example 1. An organic EL element was produced.

(Comparative Example 1)
Except for forming directly from the light emitting layer without forming a buffer layer using a charge transport material having a substituted silicon group on the surface of the glass substrate with an ITO electrode where the ITO electrode is provided. In the same manner as in Example 1, an organic EL device was produced.

(Comparative Example 2)
Except for performing the formation from the hole transport layer directly without forming the buffer layer using the charge transport material having a substituted silicon group on the surface of the glass substrate with the ITO electrode where the ITO electrode is provided, An organic EL device was produced in the same manner as in Example 2.

(Comparative Example 3)
Except for performing the formation from the hole transport layer directly without forming the buffer layer using the charge transport material having a substituted silicon group on the surface of the glass substrate with the ITO electrode where the ITO electrode is provided, An organic EL device was produced in the same manner as in Example 3.

(Comparative Example 4)
Except for forming directly from the light emitting layer without forming a buffer layer using a charge transport material having a substituted silicon group on the surface of the glass substrate with an ITO electrode where the ITO electrode is provided. In the same manner as in Example 4, an organic EL device was produced.

(Comparative Example 5)
Except for performing the formation from the hole transport layer directly without forming the buffer layer using the charge transport material having a substituted silicon group on the surface of the glass substrate with the ITO electrode where the ITO electrode is provided, An organic EL element was produced in the same manner as in Example 11.

(Comparative Example 6)
As a charge injection material for forming a buffer layer, Baytron P (PEDOT / PSS, manufactured by Bayer Co., Ltd .: polyethylene dioxide thiophene [compound (XXIV) below, ionization potential = 5.1 to 5.2 eV] and polystyrene sulfone) A mixed aqueous dispersion containing an acid) was applied to the surface of the glass substrate with an ITO electrode, on which the ITO electrode was provided, which was washed and dried by this method, and was applied at 200 ° C. to 10 ° C. An organic EL device was produced in the same manner as in Example 3 except that a buffer layer having a film thickness of 10 nm was formed after sufficiently drying by heating for a few minutes and curing.

(Comparative Example 7)
As a charge injection material for forming a buffer layer, Baytron P (PEDOT / PSS, Bayer Co., Ltd .: polyethylene dioxide thiophene [compound (XXIV), ionization potential = 5.1 to 5.2 eV] and polystyrene sulfone) A mixed aqueous dispersion containing an acid) was applied to the surface of the glass substrate with an ITO electrode, on which the ITO electrode was provided, which was washed and dried by this method, and was applied at 200 ° C. to 10 ° C. An organic EL device was produced in the same manner as in Example 11 except that a buffer layer having a film thickness of 10 nm was formed after sufficiently drying by heating for a few minutes and curing.

(Comparative Example 8)
As a charge injection material for forming a buffer layer, a low molecular weight injection material: starburst system [the compound (VIII-5), MTDATA (4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine ), An ionized potential = 5.1 eV] dissolved in 5% by weight of a chlorobenzene solution filtered through a PTFE filter having an aperture of 0.1 μm, and this solution was washed and dried, and glass with an ITO electrode An organic EL device was fabricated in the same manner as in Example 3 except that a 10 nm-thickness buffer layer was formed on the surface of the substrate on which the ITO electrode was provided by spin coating and sufficiently drying. Produced.

(Comparative Example 9)
As a charge injection material for forming the buffer layer, a chlorobenzene solution in which 5% by weight of a low molecular weight injection material: starburst system [the compound (VIII-5), MTDATA, ionization potential = 5.1 eV] is dissolved is 0 Using a solution prepared by filtering through a 1 μm PTFE filter, this solution was washed and dried, and then applied onto the surface on which the ITO electrode was provided on the glass substrate with the ITO electrode by a spin coating method. After drying, an organic EL device was produced in the same manner as in Example 11 except that a buffer layer having a thickness of 10 nm was formed.

(Comparative Example 10)
Instead of charge transporting polyurethane [compound (XII-2)] as a hole transporting material, a charge transporting polymer having a vinyl skeleton [the following compound (XXV), Mw = 5.46 × 10 ⁴ (in terms of styrene)] A device was fabricated in the same manner as in Example 3 except that the above was used.

(Comparative Example 11)
Instead of charge transporting polyurethane [compound (XII-2)] as a hole transporting material, a charge transporting polymer having a polycarbonate skeleton [the following compound (XXVI), Mw = 7.83 × 10 ⁴ (in terms of styrene)] A device was fabricated in the same manner as in Example 3 except that the above was used.

(Comparative Example 12)
Instead of charge transporting polyurethane [compound (XII-2)] as a hole transporting material, a charge transporting polymer having a vinyl skeleton [compound (XXV), Mw = 5.46 × 10 ⁴ (in terms of styrene)] A device was fabricated in the same manner as in Example 11 except that.

(Comparative Example 13)
Instead of charge transporting polyurethane [compound (XII-2)] as a hole transporting material, a charge transporting polymer having a polycarbonate skeleton [said compound (XXVI), Mw = 7.83 × 10 ⁴ (in terms of styrene)] A device was fabricated in the same manner as in Example 11 except that.

-Evaluation-
The organic EL device produced as described above was applied with a DC voltage in vacuum (133.3 × 10 ⁻³ Pa (10 ⁻⁵ Torr)) with the ITO electrode side plus and the Mg—Ag back electrode minus. The rising voltage (driving voltage) when the light was emitted, the maximum luminance, and the driving current density at the maximum luminance were evaluated. The results are shown in Table 3.
Moreover, the element lifetime of the organic EL element was measured in dry nitrogen. In the evaluation of the element lifetime, the current value was set so that the initial luminance was 50 cd / m ^2, and the time until the luminance was reduced by half from the initial value by constant current driving was defined as the element lifetime (hour). The element lifetime at this time is also shown in Table 3.

  As can be seen from Table 3, the organic EL elements shown in Examples 1 to 19 are composed of a material in which the charge injection material has a substituted silicon group containing a hydrolyzable group, and is cured to form an adjacent layer. Comparative Examples 1 to 5 in which the charge injection property and the charge balance were improved by forming a buffer layer having excellent adhesion to the anode (ITO electrode) without bleeding and excellent charge injection property, and no buffer layer was provided. It was found that the organic EL element showed more stable, high luminance, and high efficiency characteristics.

  Further, as can be seen from the comparison between Examples 3 and 11 and Comparative Examples 6 to 9, this buffer layer can be used as a buffer layer even when it is replaced with a buffer layer that may contain a low molecular component that causes bleeding. It was found that Examples 3 and 11 using the charge injection material used in the embodiment had a longer element lifetime.

  Further, as can be seen from the comparison between Examples 3 and 11 and Comparative Examples 10 to 13, Examples 3 and 11 using the charge transporting polyurethane used in this embodiment are more effective in device lifetime. It was found that the emission brightness was excellent. This is presumably because the adhesiveness to the buffer layer and charge transportability are improved in the charge transportable polyurethane in the present embodiment.

  In addition, it was found that no pinhole or peeling defect occurred during film formation in any of the examples. In addition, since a good thin film can be formed by using a spin coating method, a dip method, or the like during the production, there are few defects such as pinholes, it is easy to increase the area, and excellent durability and light emission characteristics are achieved. It turns out that you can get.

It is typical sectional drawing which shows an example of the laminated constitution of the display apparatus which concerns on this Embodiment. It is typical sectional drawing which shows an example of the laminated constitution of the display apparatus which concerns on this Embodiment. It is typical sectional drawing which shows an example of the laminated constitution of the display apparatus which concerns on this Embodiment. It is typical sectional drawing which shows an example of the laminated constitution of the display apparatus which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent insulator board | substrate 2 Transparent electrode 3 Buffer layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Light emitting layer with charge transport ability 8 Back electrode 9 Voltage application apparatus 10 Organic electroluminescent element

Claims (11)

A pair of anode and cathode, at least one of which is transparent or translucent, and an organic compound layer sandwiched between the anode and cathode electrodes,
The organic compound layer is composed of two or more layers including at least a buffer layer and a light emitting layer,
At least one of the organic compound layers includes at least one kind of charge transporting polyurethane represented by the following general formulas (I-1) and (I-2),
The buffer layer is provided in contact with the anode, and includes a cross-linking compound formed using at least one kind of charge injection material having a substituted silicon group represented by the following general formula (III):
An organic electroluminescent device characterized by the above.

(In the general formulas (I-1) and (I-2), A represents at least one selected from the structures represented by the following general formulas (II-1) and (II-2), and R represents a hydrogen atom. Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched chain having 2 to 10 carbon atoms. Represents a hydrocarbon, Y represents a divalent diisocyanate residue or a divalent amine residue, Z represents a divalent alcohol residue or a divalent bischloroformate residue, and m represents 0 or 1 , P represents an integer of 5 to 5000. The residue shown here refers to a portion excluding the reactive group of the linking compound.)

(In the general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and k represents Represents 0 or 1)

(In general formula (III), R ₁ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. A represents an integer of 1 to 3.) The organic electroluminescent element according to claim 1, wherein the charge injection material is at least one of aromatic amine compounds represented by the following general formulas (IV-1) to (IV-4).

(In the general formulas (IV-1) to (IV-4), Ar represents a substituted or unsubstituted monovalent aromatic group, and Ra represents at least one of the substituted silicon groups represented by the general formula (III). And m and l represent 0 or 1, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms.) The organic compound layer is constituted by laminating at least a buffer layer, a light emitting layer, and an electron transport layer in this order from the anode side,
At least one of the light emitting layer and the electron transport layer contains at least one charge transporting polyurethane represented by the general formulas (I-1) and (I-2),
The organic electroluminescent element according to claim 1.   The organic light emitting device according to claim 3, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane. The organic compound layer is configured by laminating at least a buffer layer, a hole transport layer, a light emitting layer, and an electron transport layer in this order from the anode side,
At least one of the hole transport layer, the light emitting layer, and the electron transport layer contains at least one kind of charge transporting polyurethane represented by the general formulas (I-1) and (I-2).
The organic electroluminescent element according to claim 1.   The organic electroluminescent element according to claim 5, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane. The organic compound layer is configured by laminating at least a buffer layer, a hole transport layer, and a light emitting layer in this order from the anode side,
At least one layer of the hole transport layer and the light emitting layer contains at least one kind of charge transport polyurethane represented by the general formulas (I-1) and (I-2),
The organic electroluminescent element according to claim 1.   8. The organic electroluminescent element according to claim 7, wherein the light emitting layer contains a charge transporting material other than the charge transporting polyurethane. The organic compound layer is configured by laminating at least a buffer layer and a light emitting layer having charge transporting ability in this order,
2. The organic electric field according to claim 1, wherein the light emitting layer having the charge transporting capability contains at least one charge transporting polyurethane represented by the general formulas (I-1) and (I-2). Light emitting element.   The organic electroluminescent element according to claim 9, wherein the light emitting layer having the charge transporting capability contains a charge transporting material other than the charge transporting polyurethane. An organic electroluminescent device arranged in a matrix, and a driving means for driving the organic electroluminescent device,
The organic electroluminescent element has a pair of an anode and a cathode, at least one of which is transparent or translucent, and an organic compound layer sandwiched between electrodes of the anode and the cathode,
The organic compound layer is composed of two or more layers including at least a buffer layer and a light emitting layer,
At least one of the organic compound layers includes at least one kind of charge transporting polyurethane represented by the following general formulas (I-1) and (I-2),
The buffer layer is provided in contact with the anode, and includes a cross-linking compound formed using at least one kind of charge injection material having a substituted silicon group represented by the following general formula (III):
A display device characterized by that.

(In the general formulas (I-1) and (I-2), A represents at least one selected from the structures represented by the following general formulas (II-1) and (II-2), and R represents a hydrogen atom. Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched chain having 2 to 10 carbon atoms. Represents a hydrocarbon, Y represents a divalent diisocyanate residue or a divalent amine residue, Z represents a divalent alcohol residue or a divalent bischloroformate residue, and m represents 0 or 1 , P represents an integer of 5 to 5000. The residue shown here refers to a portion excluding the reactive group of the linking compound.)

(In the general formulas (II-1) and (II-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and k represents Represents 0 or 1)

(In general formula (III), R ₁ represents hydrogen, an alkyl group, or a substituted or unsubstituted aryl group. Q represents a hydrolyzable group. A represents an integer of 1 to 3.)

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