JP4779325B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescent element (hereinafter sometimes referred to as “organic EL element”), and more particularly, to an organic electroluminescent element using a specific charge transporting polymer.

  An electroluminescent element (hereinafter referred to as an “EL element”) is a self-luminous all-solid-state element, and is highly visible and resistant to impacts. At present, the one using an inorganic phosphor is the mainstream, but since an AC voltage of 200 V or more is required for driving, there are problems such as high manufacturing cost and insufficient brightness.

On the other hand, research on EL devices using organic compounds first 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).
However, the thin film obtained by this method still has a high driving voltage of 30 V, a low density of electron / hole carriers in the film, and a low probability of photon generation due to carrier recombination. It was not obtained.

However, in recent years, in a function-separated EL 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 / s at a low voltage of about 10V. There has been a report that high brightness of m ² or more can be obtained (see Non-Patent Document 2). Since this research report, research and development of stacked EL 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.

However, this type of EL device has the following problems for practical use.
(1) Since it is driven at a high current density of several mA / cm ² , a large amount of Joule heat is generated. For this reason, there is a phenomenon that the hole transporting low molecular weight compound or the fluorescent organic low molecular weight compound formed into a film in an amorphous glass state by vapor deposition is gradually crystallized and finally melted, resulting in a decrease in luminance and dielectric breakdown. It is often observed, and as a result, the lifetime of the device is reduced.
(2) Since a low molecular organic compound is formed into a thin film of 0.1 μm or less in a plurality of vapor deposition steps, pinholes are likely to occur, and in order to obtain sufficient performance, the film thickness is controlled under strictly controlled conditions. It is necessary to control. Therefore, productivity is low and it is difficult to increase the area.

In order to solve the problem shown in (1), a starburst amine capable of obtaining a stable amorphous glass state is used as a hole transport material (see, for example, Non-Patent Document 3), or the side chain of polyphosphazene is used. An EL device using a polymer into which triphenylamine is introduced (see Non-Patent Document 4) has been reported.
However, since these materials alone have an energy barrier due to the ionization potential of the hole transport material, they do not satisfy the hole injection property from the anode or the hole injection property to the light emitting layer. In the case of the former starburst amine, it is difficult to purify because of its low solubility, and in the case of the latter polymer, a high current density cannot be obtained and sufficient luminance is obtained. There is also a problem such as not.

  Next, in order to solve the problem shown in (2), research and development of an organic EL element having a single-layer structure capable of shortening the process has been advanced, and a conductive polymer such as poly (p-phenylene vinylene) is used. Devices (for example, see Non-Patent Document 5) and devices in which an electron transport material and a fluorescent dye are mixed in hole-transporting polyvinyl carbazole (see Non-Patent Document 6) have been proposed. Luminous efficiency and the like are not as good as those of a stacked organic EL device using an organic low molecular weight compound.

  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). However, since the charge transport material has poor solubility and compatibility with solvents and resins, it is easy to crystallize, and there is a problem in production or characteristics.

In addition, display devices using organic EL elements are more suitable for miniaturization and thinning than other display devices such as liquid crystal, and are expected to be used for portable devices driven by an internal power supply. . 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 EL element is that a hole transport layer (or a light emitting layer having charge transport capability) 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 use as described above 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), A method for improving the charge injection efficiency into the hole 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)

  By the way, when the buffer layer is provided, the drive voltage can surely be lowered. However, when manufacturing an organic EL element provided with a buffer layer or when a device using this element is used for a long time, such as when used for a long time, various manufacturing factors that cause a decrease in yield It has been found that defects and deterioration of device performance over time may occur and may not withstand practical use.

  Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to have sufficient luminance, excellent stability and durability, and capable of large area and easy to manufacture. Another object of the present invention is to provide an organic EL device in which the occurrence of manufacturing defects is small and the degradation of device performance with time is small.

  In order to achieve the above-mentioned problems, the present inventors diligently studied the causes of various manufacturing defects or deterioration of device performance over time when an organic EL device provided with a buffer layer was produced. .

  First, the present inventors use a polymer charge transporting material on the surface of the buffer layer formed on the anode to form a hole transport layer or a light emitting layer having charge transport ability (hereinafter directly on the buffer layer). Alternatively, a problem was observed when trying to form a layer formed indirectly through another layer (sometimes abbreviated as “adjacent layer”). As a result, the charge transporting polymer used is a vinyl skeleton (for example, PTPDMA (see Polymer Journal, Vol. 52, 216 (1995))) or a polycarbonate skeleton (for example, Et-TPAPEK (43rd) In the case of the Applied Physics-related Joint Lecture Proceedings 27a-SY-19, pp. 1126 (1996))), the adhesion between the buffer layer and the adjacent layer becomes insufficient, and peeling defects occur. In addition, it was confirmed that pinholes may be generated or aggregation may occur. As a cause of such a defect, it is considered that the familiarity at the interface between the buffer layer and the adjacent layer and the lack of flexibility of the polymer constituting the adjacent layer are considered.

  Therefore, the present inventors have used a material having a highly flexible molecular structure as the charge transporting polymer used for forming the adjacent layer in terms of preventing defects in film formation, or Even if the material has a molecular structure with low flexibility as described above, by reducing the size of the molecule itself (decreasing the molecular weight), the flexibility of the molecule can be improved, We thought that it was possible to cope by making arrangement easy.

  The inventors also investigated the cause of the deterioration of the device performance over time. 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, low molecular components (for example, starburst amine, CuPc, or counter ions of an ionic substance used in combination with PEDOT) contained in the buffer layer are caused by Joule heat generated when an electric field is applied to the device. It was found that the original function of the adjacent layer could not be exhibited by bleeding to the adjacent layer with time. In addition, the occurrence of such bleed is that the low molecular component in the buffer layer easily penetrates into the adjacent layer formed using the charge transporting polymer of the vinyl skeleton or the polycarbonate skeleton, in other words, This means that the gap between charge transporting polymers in adjacent layers is large / is easily formed.

  Therefore, the present inventors consider that in order to suppress bleed, it is important to form a dense and highly heat-resistant adjacent layer so that bleed to the adjacent layer of low molecular components can be prevented. It was. In this case, gaps between molecules that promote bleeding of low molecular components can be filled without gaps in the formation of adjacent layers, and relative movement between molecules occurs in the adjacent layers once formed by heat. It is important to prevent bleed from not generating gaps between molecules.

  Therefore, from the viewpoint of suppressing bleeding, it is necessary to use a material having a highly flexible molecular structure having high heat resistance (glass transition temperature) as the charge transporting polymer forming the adjacent layer. However, this condition is in conflict with the use of a charge transporting polymer with a low molecular weight having a low-flexibility molecular structure, which is one option for suppressing defects in film formation.

  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 or more of hopping sites responsible for charge transfer in the molecule in order to ensure charge mobility that determines the most important light emission characteristics of the organic EL element. There is. That is, in other words, a molecular size (molecular weight) of a certain degree or more is necessarily required. However, as in the case of bleed suppression, this condition is also in conflict with the use of a low molecular weight charge transporting polymer having a low-flexibility molecular structure, which is one of the options for suppressing film defects. is there.

  That is, it is difficult to form a dense adjacent layer in order to suppress bleed by a charge transporting polymer lacking in flexibility of molecular structure, while heat resistance can be reduced by reducing the molecular weight in order to suppress bleed. However, there is a dilemma that is fundamentally difficult to solve, such as the promotion of bleeding due to the lowering of the property and the lowering of the charge mobility itself related to the basic characteristics of the device.

  Therefore, when considering the practicality that can withstand long-term use in addition to securing the basic characteristics of light emission characteristics in obtaining an organic EL element provided with a buffer layer, the present inventors. As a charge transporting polymer used for forming the adjacent layer, when a material causing bleed is used as a buffer layer, it has not only sufficient charge mobility but also a highly flexible molecular structure. And it was considered important to use a material that also had high heat resistance. Furthermore, in order to drastically suppress bleed, it was considered necessary to form the buffer layer using components that basically do not require the use of low molecular components that cause bleed.

  For this reason, as a result of intensive studies to achieve the above object, the inventors include at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure. It has been found that charge transporting polyethers have charge mobility and thin film forming ability suitable for organic EL devices, and more charge injection is provided by providing at least one buffer layer in contact with the electrode layer (anode). As a result, the inventors have found that the organic EL device can function as an organic EL device having improved durability, high efficiency, high luminance, and durability, and has completed the present invention. That is, the present invention is as follows.

<1> An organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, wherein the organic compound layer is at least a light emitting layer, a buffer layer, and an electron transport layer Consisting of
At least one of the light emitting layer and the electron transporting layer contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light emitting layer, and is represented by the following general formulas (II-1) to (II-4) as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from structural units.

<2> It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer includes at least a light emitting layer, a buffer layer, a hole transport layer, And consisting of an electron transport layer,
  At least one of the hole transport layer and the electron transport layer contains at least one charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
  The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by:

  <3> It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer includes at least a light emitting layer, a buffer layer, and hole transport Composed of layers,
  At least one of the hole transport layer and the light emitting layer contains at least one charge transport polyether, and the charge transport polyether is a charge transport polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
  The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by:

<4> An organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, wherein the organic compound layer includes only a light emitting layer and a buffer layer, and the light emission The layer is a light-emitting layer having charge transporting capability;
The light emitting layer having the charge transporting capability contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light-emitting layer having charge transport ability, and the following general formulas (II-1) to (II) are used as one or more kinds of charge injection materials. 4) An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by 4) .

<5> The organic electroluminescence device according to <1>, <2>, <3>, or <4>, wherein at least one ionization potential of the charge injection material is 5.2 eV or less .

<6> The organic electroluminescent element as described in <1>, wherein the light emitting layer contains a charge transporting material.

<7> The organic electroluminescent element as described in <2>, wherein the light emitting layer contains a charge transporting material.

<8> The organic electroluminescent element as described in <3>, wherein the light emitting layer contains a charge transporting material.

<9> The organic electroluminescent element according to <4>, wherein the light emitting layer having charge transporting capability contains a charge transporting material.

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A bivalent linear hydrocarbon group having 1 to 6 carbon atoms or a branched hydrocarbon group having 2 to 10 carbon atoms is represented, and m and k each independently represent 0 or 1. ]

[In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

(In the general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, m and l each independently represent 0 or 1, and T represents 1 carbon atom. Represents a divalent linear hydrocarbon of ˜6 or a branched hydrocarbon of 2 to 10 carbon atoms.)

  As described above, according to the present invention, the device has sufficient luminance, is excellent in stability and durability, can be increased in area, is easy to manufacture, has fewer defects in manufacturing, and has an element. It is possible to provide an organic EL element with little deterioration in performance over time.

The organic EL device of the present invention is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer includes at least a light emitting layer and a buffer layer. The organic compound layer contains at least one kind of the charge transporting polyether, and the charge transporting polyether is represented by the following general formulas (I-1) and (I-2): ), The buffer layer is provided in contact with the anode, and contains one or more charge injection materials. It is characterized by that.
However, in the organic EL device of the present invention, the following <1> and <2>. The organic EL element of <3> or <4> is adopted.
<1> It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer is at least a light emitting layer, a buffer layer, and an electron transport layer Consisting of
At least one of the light emitting layer and the electron transporting layer contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light emitting layer, and is represented by the following general formulas (II-1) to (II-4) as one or more kinds of charge injection materials. An organic EL device containing a charge transporting polymer having at least one selected from structural units.
<2> It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer includes at least a light emitting layer, a buffer layer, a hole transport layer, And consisting of an electron transport layer,
At least one of the hole transport layer and the electron transport layer contains at least one charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic EL device comprising a charge transporting polymer having at least one selected from the structural units represented by:
<3> It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer includes at least a light emitting layer, a buffer layer, and hole transport Composed of layers,
At least one of the hole transport layer and the light emitting layer contains at least one charge transport polyether, and the charge transport polyether is a charge transport polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic EL device comprising a charge transporting polymer having at least one selected from the structural units represented by:
<4> An organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent. The organic compound layer is composed only of a light emitting layer and a buffer layer, and the light emission The layer is a light-emitting layer having charge transporting capability;
The light emitting layer having the charge transporting capability contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light-emitting layer having charge transport ability, and the following general formulas (II-1) to (II) are used as one or more kinds of charge injection materials. -4) An organic EL device containing a charge transporting polymer having at least one selected from the structural units represented by 4).

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A bivalent linear hydrocarbon group having 1 to 6 carbon atoms or a branched hydrocarbon group having 2 to 10 carbon atoms is represented, and m and k each independently represent 0 or 1. ]

  The organic EL device of the present invention has a charge in which at least one of the organic compound layers has a repeating unit containing at least one selected from the structures represented by formulas (I-1) and (I-2) as a partial structure A buffer layer containing one or more charge injection materials is provided in contact with the anode, including a transportable polyether (hereinafter sometimes referred to simply as “charge transporting polyether”); It has sufficient luminance, is excellent in stability and durability, can be driven at a lower voltage, and can consume less power than in the past.

In addition, the charge transporting polyether has high mobility of the ether bond site, so the molecular structure is highly flexible, and even if the molecular weight is increased to ensure heat resistance, the flexibility of the molecular structure is lost. Hard to break.
For this reason, even if the buffer layer contains a low molecular component that causes bleeding, when the adjacent layer is formed using this charge transporting polyether, sufficient charge mobility required as a charge transporting material is secured. In addition, there are few defects such as pinholes and agglomeration and the adhesiveness with the buffer layer is excellent, and even when used for a long time, bleeding can be suppressed.

  Moreover, since the organic EL device of the present invention is produced using a charge transporting polyether, the area can be increased and the production can be easily performed. Further, as will be described later, the charge transporting polyether can impart both functions of hole transporting ability and electron transporting ability by appropriately selecting the 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 or the like depending on the purpose.

  The charge transporting polyether having a repeating unit containing at least one selected from the structures represented by formulas (I-1) and (I-2) as a partial structure will be described in detail.

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

Here, in general formulas (I-1) and (I-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. In the condensed ring aromatic hydrocarbon, a fully condensed ring aromatic hydrocarbon is preferable. In the present invention, the polynuclear aromatic hydrocarbon and the condensed ring aromatic hydrocarbon specifically mean a polycyclic aromatic as defined below.
That is, “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.
In addition, “fused ring aromatic hydrocarbon” means that there are two or more aromatic rings composed of carbon and hydrogen, and these aromatic rings share a pair of adjacent bonded carbon atoms. Represents a hydrocarbon compound. Specific examples include naphthalene, anthracene, phenanthrene, fluorene and the like.

  In the general formulas (I-1) and (I-2), the aromatic heterocycle selected as one of the structures representing Ar represents an aromatic ring including elements other than carbon and hydrogen. The number of atoms (Nr) constituting the ring skeleton is preferably Nr = 5 and / or 6. 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 2 are included in the ring skeleton. One or more hetero 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 The heterocyclic ring substituted with is preferably used, and pyridine is preferably used as the heterocyclic ring having a 6-membered ring structure.

  Furthermore, in the general formulas (I-1) and (I-2), the aromatic group containing an aromatic heterocycle selected as one of the structures representing Ar is at least in the atomic group constituting the skeleton. It represents a linking group containing one kind of the aromatic heterocycle. These may be either all composed of conjugated systems or partially composed of non-conjugated systems, but all composed of conjugated systems in terms of charge transportability and luminous efficiency. preferable.

  As a substituent of an aromatic group including a benzene ring, a polynuclear aromatic hydrocarbon, a condensed ring aromatic hydrocarbon, an aromatic heterocyclic ring or an aromatic heterocyclic ring selected as a structure representing Ar, a hydrogen atom, an alkyl group, Examples include an alkoxy group, a phenoxy group, an aryl group, an aralkyl group, a substituted amino group, and a halogen atom. As an alkyl group, a C1-C10 thing is preferable, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group etc. are mentioned. As an alkoxy group, a C1-C10 thing is preferable, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group etc. are mentioned. As an aryl group, a C6-C20 thing is preferable, for example, a phenyl group, a toluyl group, etc. are mentioned. As the aralkyl group, those having 7 to 20 carbon atoms are preferable, 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 (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group. Specifically, a substituted or unsubstituted phenylene group, a substituted or unsubstituted divalent polynuclear aromatic hydrocarbon having 2 to 10 aromatics, or a substituted or unsubstituted divalent aromatic hydrocarbon having 2 to 10 aromatics A 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 (I-1) and (I-2), m and k each independently represent 0 or 1, and T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms, or 2 to 2 carbon atoms. 10 is a divalent branched hydrocarbon group, preferably a divalent straight chain hydrocarbon group having 2 to 6 carbon atoms, and a divalent branched chain hydrocarbon group having 3 to 7 carbon atoms. More selected. The specific structure of T is shown below.

  The charge transporting polyether comprising a repeating unit containing at least one selected from the structures represented by formulas (I-1) and (I-2) as a partial structure is represented by the following formula (VI). Charge transporting polyethers are preferably used.

  [In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

  In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and one polymer contains two or more types of structures A. May be.

  In general formula (VI), R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. As an alkyl group, a C1-C10 thing is preferable, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group etc. are mentioned. As an aryl group, a C6-C20 thing is preferable, for example, a phenyl group, a toluyl group, etc. are mentioned. As the aralkyl group, those having 7 to 20 carbon atoms are preferable, and examples thereof include a benzyl group and a phenethyl group. 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 formula (VI), p representing the degree of polymerization is in the range of 3 to 5,000, preferably in the range of 10 to 1,000. The weight average molecular weight _Mw of the charge transporting polyether of the present invention is in the range of 5,000 to 1,000,000, but is preferably in the range of 10,000 to 300,000.

  The charge transporting polyether of the present invention is synthesized by polymerizing a charge transporting monomer having two hydroxyalkyl groups represented by the following structural formulas (VII-1) and (VII-2) by the following method. can do. In Structural Formula (VII-1) or (VII-2), Ar, X, T, m, and k are Ar, X, T, m in General Formula (I-1) or (I-2), respectively. , K.

  In particular, the charge transporting polyether represented by the general formula (VI) can be obtained, for example, by a synthesis method represented by << 1 >>, << 2 >>, or << 3 >>.

  << 1 >> The charge transporting polyether represented by the general formula (VI) can be synthesized by a method in which the charge transporting compound (charge transporting monomer) having the two hydroxyalkyl groups is subjected to heat dehydration condensation. In this case, it is desirable to heat and melt the charge transporting monomer without solvent and to react under reduced pressure in order to promote the polymerization reaction by dehydration of water. When a solvent is used, a solvent azeotropic with water, for example, trichloroethane, toluene, chlorobenzene, dichlorobenzene, nitrobenzene, 1-chloronaphthalene, etc. is effective for removing water, and 1 equivalent of a charge transporting monomer 1 to 100 equivalents, preferably 2 to 50 equivalents. The reaction temperature can be arbitrarily set, but it is preferable to carry out the reaction at the boiling point of the solvent in order to remove water generated during the polymerization. If the polymerization does not proceed, the solvent may be removed from the reaction system and heated and stirred in a viscous state.

  << 2 >> Further, the charge transporting polyether represented by the general formula (VI) is a protonic acid such as p-toluenesulfonic acid, hydrochloric acid, sulfuric acid or trifluoroacetic acid, or a Lewis acid such as zinc chloride as an acid catalyst. It can also be synthesized by a method of dehydration condensation using In this case, the acid catalyst is used in a range of 1/10000 to 1/10 equivalent, preferably 1/1000 to 1/50 equivalent, per equivalent of charge transporting monomer. In order to remove water generated during the polymerization, it is preferable to use a solvent azeotropic with water. As the solvent, toluene, chlorobenzene, dichlorobenzene, nitrobenzene, 1-chloronaphthalene and the like are effective, and 1 to 100 equivalents, preferably 2 to 50 equivalents, are used with respect to 1 equivalent of the charge transporting monomer. The reaction temperature can be arbitrarily set, but it is preferable to carry out the reaction at the boiling point of the solvent in order to remove water generated during the polymerization.

  << 3 >> Further, the charge transporting polyether represented by the general formula (VI) includes alkyl isocyanates such as cyclohexyl isocyanate, p-tolyl cyanate, 2,2-bis (4-cyanatophenyl) propane, and the like. It can also be synthesized by a method using a condensing agent such as cyanate ester, dichlorohexylcarbodiimide (DCC), trichloroacetonitrile. In this case, the condensing agent is used in a range of 1/2 to 10 equivalents, preferably 1 to 3 equivalents, relative to 1 equivalent of the charge transporting monomer. As the solvent, toluene, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like are effective, and 1 to 100 equivalents, preferably 2 to 50 equivalents, are used with respect to 1 equivalent of the charge transporting monomer. Although reaction temperature can be set arbitrarily, it is preferable to make it react by the boiling point of a solvent from room temperature.

  Of the synthetic methods of the above << 1 >>, << 2 >> and << 3 >>, the isomerization and side reactions are unlikely to occur, and therefore the synthetic method << 1 >> or << 3 >> is preferable. In particular, the synthesis method << 3 >> is more preferable because the reaction conditions are mild. If the solvent is not used after completion of the reaction, it is dissolved in a soluble solvent. When a solvent is used, it is dropped as it is in a poor solvent in which alcohols such as methanol and ethanol and charge transporting polymers such as acetone are difficult to dissolve, to precipitate the charge transporting polymer, After separation, wash thoroughly with water or organic solvent and dry. Furthermore, if necessary, the reprecipitation treatment may be repeated in which it is dissolved in a suitable organic solvent and dropped into a poor solvent to precipitate the charge transporting polymer. The reprecipitation treatment is preferably performed while stirring efficiently with a mechanical stirrer or the like. In the reprecipitation treatment, the solvent for dissolving the charge transporting polymer is used in the range of 1 to 100 equivalents, preferably 2 to 50 equivalents, per 1 equivalent of the charge transporting polymer. The poor solvent is used in an amount of 1 to 1000 equivalents, preferably 10 to 500 equivalents, per 1 equivalent of the charge transporting polymer. Furthermore, in the above reaction, a copolymer can be synthesized by using two or more charge transporting monomers, preferably 2 to 5, more preferably 2 to 3. By copolymerizing different kinds of charge transporting monomers, it is possible to control electrical characteristics, film formability, and solubility. If the degree of polymerization p of the charge transporting polymer is too low, the film formability is inferior and it is difficult to obtain a strong film, and if it is too high, the solubility in the solvent becomes low and the processability deteriorates. The range is set, preferably 10 to 3000, and more preferably 15 to 1000. The terminal group of the charge transporting polymer may be a hydroxyl group, that is, R may be a hydrogen atom, as in the case of the charge transporting monomer, but in the case of affecting the polymer physical properties such as solubility, film formability, and mobility. The end group R can be modified to control the physical properties. For example, the terminal hydroxyl group can be alkyl etherified with alkyl sulfate, alkyl iodide or the like. The specific reagent can be arbitrarily selected from dimethyl sulfate, diethyl sulfate, methyl iodide, ethyl iodide and the like, and is 1 to 3 equivalents, preferably 1 to 2 equivalents with respect to the terminal hydroxyl group. Use in a range. At that time, a base catalyst can be used, but the base catalyst can be arbitrarily selected from sodium hydroxide, potassium hydroxide, sodium hydride, sodium metal, etc. It is used in the range of 3 equivalents, preferably 1-2 equivalents. The reaction temperature can be from 0 ° C. to the boiling point of the solvent used.

  In addition, the solvent used at that time is selected from inert solvents such as benzene, toluene, methylene chloride, tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone. However, a single solvent or a mixed solvent of 2 to 3 types can be used. Depending on the reaction, a quaternary ammonium salt such as tetra-n-butylammonium iodide can be used as a phase transfer catalyst. It is also possible to acylate the terminal hydroxyl group with an acid halide to convert the group R into an acyl group. The acid halide is not particularly limited. For example, acryloyl chloride, crotonoyl chloride, methacryloyl chloride, n-butyl chloride, 2-furoyl chloride, benzoyl chloride, cyclohexanecarbonyl chloride, enanthyl chloride, phenylacetyl chloride, Examples include o-toluoyl chloride, m-toluoyl chloride, p-toluoyl chloride, and the like, and it is used in the range of 1 to 3 equivalents, preferably 1 to 2 equivalents with respect to the terminal hydroxyl group.

  In this case, a base catalyst can be used, and the base catalyst can be arbitrarily selected from pyridine, dimethylaminopyridine, trimethylamine, triethylamine and the like, and is 1 to 3 equivalents, preferably 1 to 1 with respect to the acid chloride. Used in the range of 2 equivalents. Examples of the solvent used at that time include benzene, toluene, methylene chloride, tetrahydrofuran, and methyl ethyl ketone. The reaction can be carried out from 0 ° C. at the boiling point of the solvent used. Preferably, it is used in the range of 0 ° C to 30 ° C. Furthermore, acylation can also be performed using an acid anhydride such as acetic anhydride. When using a solvent, specifically, an inert solvent such as benzene, toluene or chlorobenzene can be used. The reaction can be carried out from 0 ° C. to the boiling point of the solvent. Preferably, it may be carried out from 50 ° C. to the boiling point of the solvent. In addition, a urethane residue (—CONH—R ′) can be introduced at the terminal using monoisocyanate. Specific monoisocyanates include isocyanic acid benzyl ester, isocyanic acid n-butyl ester, isocyanic acid t-butyl ester, isocyanic acid cyclohexyl ester, isocyanic acid 2,6-dimethyl ester, isocyanic acid ethyl ester, isocyanic acid isopropyl ester, Isocyanic acid 2-methoxyphenyl ester, isocyanic acid 4-methoxyphenyl ester, isocyanic acid n-octadecyl ester, isocyanic acid phenyl ester, isocyanic acid isopropyl ester, isocyanic acid m-tolyl ester, isocyanic acid p-tolyl ester, isocyanic acid 1 -It can be arbitrarily selected from naphthyl esters and the like, and is used in the range of 1 to 3 equivalents, preferably 1 to 2 equivalents with respect to the terminal hydroxyl group. Examples of solvents used in this case include benzene, toluene, chlorobenzene, dichlorobenzene, methylene chloride, tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Can do. The reaction temperature can be from 0 ° C. to the boiling point of the solvent used. When the reaction is difficult to proceed, a metal compound such as dibutyltin (II) dilaurate, octyltin (II), lead naphthenate, or a tertiary amine such as triethylamine, trimethylamine, pyridine, dimethylaminopyridine may be added as a catalyst. it can.

Next, the layer structure of the organic EL element of the present invention will be described in detail.
The organic EL device of the present invention includes 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 anodes and cathodes. It has a layer structure including an organic compound layer including the above layers.
Here, 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 polyether and the light emitting polymer.

In the organic EL device of the present invention, when the organic compound layer is composed only of a buffer layer and a light emitting layer, this light emitting layer means a light emitting layer having charge transporting ability, and the light emitting layer having this charge transporting ability. Contains the charge transporting polyether.
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 polyether is contained 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. , A structure including a hole transport layer and a light emitting layer. In this case, the charge transporting polyether is preferably contained in at least one of these layers (hole transport layer, charge transport layer, light emitting layer). Furthermore, in the organic EL device of the present invention, the light emitting layer may contain a charge transporting material (a hole transporting material other than the charge transporting polyether, an electron transporting material). Details of the transportable material will be described later.

  Hereinafter, the organic EL element of the present invention 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 EL device of the present invention. In the case of FIGS. 1, 2, and 3, the organic compound layer has a three-layer structure or a four-layer structure. FIG. 4 shows an example in which the organic compound layer has a two-layer structure. In FIG. 1 to FIG. 4, components having similar functions are described with the same reference numerals.

The organic EL element 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. The organic EL element 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. The organic EL element 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. The organic EL element 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.
1-4, the transparent electrode 2 means an anode, and the back electrode 8 means a cathode. Each will be described in detail below.

  Depending on the structure of the organic compound layer containing the charge transporting polyether used in the present invention, both the light emitting layer 5 and the electron transporting layer 6 function in the case of the layer structure of the organic EL element shown in FIG. In the case of the layer structure of the organic EL element shown in FIG. 2, all of them can act as the hole transport layer 3, the light emitting layer 5, and the electron transport layer 6, and are shown in FIG. In the case of the layer structure of the organic EL element, both can act as the hole transport layer 3 and the light emitting layer 7 having charge transport ability. In the case of the layer structure of the organic EL element shown in FIG. It can act as the light emitting layer 7 having.

  In the case of the layer structure of the organic EL element shown in FIGS. 1 to 4, the transparent insulator substrate 1 is preferably transparent in order to extract emitted light, and glass, plastic film, etc. are used, but are not limited thereto. . Further, the transparent electrode 2 is transparent for taking out light emission like the transparent insulator substrate, and preferably has a high work function (ionization potential) for injecting holes, indium tin oxide (ITO), An oxide film such as tin oxide (NESA), indium oxide, and zinc oxide, and gold, platinum, palladium, and the like deposited or sputtered are used, but not limited thereto.

  The buffer layer 3 is formed in contact with the anode (the transparent electrode 2 shown in FIGS. 1 to 4) and contains one or more charge injection materials. This 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. Then, in order to improve the charge injection property into the light emitting layer 7) having a charge transporting capability, it is preferable to include a charge injection material having a work function (ionization potential) of 5.2 eV or less, more preferably 5.1 eV or less. In this case, the charge injection material is contained. The number of layers constituting the buffer layer is not particularly limited, but one or two layers are preferable.

Examples of such a charge injection material include a charge transporting polymer having at least one of structural units represented by the following general formulas (II-1) to (II-4), and a structural unit represented by the general formula (III). And a charge transporting compound represented by the general formula (IV), or a charge transporting compound represented by the structural formula (V).
The material constituting the buffer layer 3 may be only one of these charge injection materials, but a mixture of two or more types can also be used, and other charge injection properties such as a binder resin can be used. A material that does not have can be used as required.

In general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, k, m, and l represent 0 or 1, and T represents 1 to 6 carbon atoms. Represents a divalent linear hydrocarbon or a branched hydrocarbon having 2 to 10 carbon atoms. Specific examples of Ar and T in the general formulas (II-1) to (II-4) are the same as the specific examples of Ar and T shown in the general formulas (I-1) and (I-2). Things can be mentioned.
The structures represented by the general formulas (II-1) to (II-2) are those in which the part represented by X in the structure represented by the general formula (I-1) is biphenyl or terphenyl. In the structures represented by the formulas (II-3) to (II-4), the moiety represented by X in the structure represented by the general formula (I-2) is biphenyl or terphenyl.
In addition, if a charge transporting polymer as shown in the general formulas (II-1) to (II-4) is used as the charge injection material, it is necessary to use a low molecular component that causes bleeding when forming the buffer layer. Therefore, the occurrence of bleeding can be fundamentally prevented.

  In general formula (III), n represents an integer within the range of 100 to 10,000, and preferably represents an integer of 1000 to 2500. The compound represented by the general formula (III) is a so-called PEDOT (polyethylene dioxythiophene) material, and when a buffer layer is formed, PEDOT alone cannot ensure sufficient conductivity. It is always used together with an ionic substance containing a counter ion (for example, Na ion) such as PSS (polystyrene sulfonic acid).

In general formula (IV), Ar represents a substituted or unsubstituted monovalent phenyl group, a substituted or unsubstituted 1-naphthyl group, or a substituted or unsubstituted 2-naphthyl group.

  When the buffer layer 3 is referred to as a charge transporting polymer (hereinafter referred to as “first charge transporting polymer”) having at least one structural unit represented by the general formulas (II-1) to (II-4) The first charge transporting polymer is at least one of the structural units represented by the general formulas (II-1) to (II-4). It is preferable to form a part or bond to a polymer. In this case, the phosphorescent portion and the fluorescent portion of the structural unit that forms part of the polymer or is bonded to the polymer forms the main chain of the first charge transporting polymer. Or may form a side chain of the first charge transporting polymer.

However, “part of the polymer” means that any of the structural units represented by the general formulas (II-1) to (II-4) is at least a repeating unit of the first charge transporting polymer. It means that it constitutes one kind.
In this case, if the first charge transporting polymer is a copolymer composed of two or more kinds of repeating units, at least one monomer used for the synthesis of the first charge transporting polymer is generally One of the structural units represented by formulas (II-1) to (II-4) is included. Further, any of the structural units represented by the general formulas (II-1) to (II-4) may constitute the main chain of the first charge transporting polymer, and side chains (pendant groups, etc.) ) May be configured.

In addition, “bonded to a polymer” means that the first charge transporting polymer substantially includes the structural unit represented by the general formulas (II-1) to (II-4) as a repeating unit. This means that any of the structural units represented by the general formulas (II-1) to (II-4) may be bonded regardless of the form in any polymer structure.
In this case, in the first charge transporting polymer, any one of the structural units represented by the general formulas (II-1) to (II-4) is represented by the general formulas (II-1) to (II-4). The polymer main chain or side chain (including a pendant group) that basically does not contain the structural unit shown as a repeating unit is included, but is not limited to such a form.

Although the molecular structure of the first charge transporting polymer containing at least one structural unit represented by the general formulas (II-1) to (II-4) is not particularly limited, specifically, for example, (1) polyester , A polymer containing the structural unit in the main chain such as polyether or polyurethane and / or a derivative thereof, (2) a polymer having the structural unit in the side chain such as polystyrene or poly (meth) acrylic acid, and / or These derivatives, or (3) a polymer obtained by combining the structures (1) and (2) above can be used.
The degree of polymerization of the first charge transporting polymer is preferably in the range of 3 to 5,000, and more preferably in the range of 10 to 1,000. The weight average molecular weight _Mw is preferably in the range of 5,000 to 1,000,000, and more preferably in the range of 10,000 to 300,000.

When the buffer layer 3 includes a charge transporting polymer having a structural unit represented by the general formula (III) (hereinafter sometimes abbreviated as “second charge transporting polymer”), the second charge transporting In order to improve the charge injection property of the buffer layer 3, the functional polymer is used by mixing with an ionic substance such as polystyrene sulfonic acid (PSS).
Specifically, as the mixture containing the second charge transporting polymer and polystyrene sulfonic acid, Baytron P (manufactured by Bayer Co., Ltd .: mixed water containing polyethylene dioxide thiophene and polystyrene sulfonic acid) Known materials such as (dispersion liquid) can be used.

When the buffer layer 3 includes a charge transporting material represented by the general formula (IV), Ar in the general formula (IV) is a substituted or unsubstituted monovalent phenyl group, a substituted or unsubstituted 1-naphthyl group. Or a substituted or unsubstituted 2-naphthyl group.
In this case, examples of the substituent of the substituted phenyl group include a hydrogen atom, an alkyl group, an alkoxy group, a phenoxy group, an aryl group, an aralkyl group, a substituted amino group, and a halogen atom. As an alkyl group, a C1-C10 thing is preferable, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group etc. are mentioned. As an alkoxyl group, a C1-C10 thing is preferable, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group etc. are mentioned. 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, and examples thereof include benzyl group and phenethyl group. Is mentioned. 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 the case of the layer structure of the organic EL element shown in FIGS. 1 and 2, the electron transport layer 6 may be formed of the charge transporting polyether alone provided with a function (electron transport ability) according to the purpose. In order to adjust the electron mobility for the purpose of, for example, further improving the electrical characteristics, an electron transport material other than the charge transporting polyether is mixed and dispersed in the range of 1 to 50% by weight. May be.
As such an electron transporting material, an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyrandioxide derivative, a fluorenylidenemethane derivative, and the like are preferable. Specific examples include the following compounds (VIII-1) to (VIII-3), but are not limited thereto. In addition, when forming the electron transport layer 6 without using the said charge transportable polyether, the electron transport layer 6 is formed using these electron transport materials.

In the case of the layer structure of the organic EL element shown in FIGS. 2 and 3, the hole transport layer 3 is formed of a charge transporting polyether having a function (hole transport ability) according to the purpose. However, in order to adjust the hole mobility, a hole transport material other than the charge transporting polyether may be mixed and dispersed in the range of 1 wt% to 50 wt%.
Examples of such hole transporting materials include tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, arylhydrazone derivatives, porphyrin compounds, and the following compounds (IX-1) to ( IX-6), and a tetraphenylenediamine derivative is preferred because of its good compatibility with the charge transporting polyether. Moreover, you may mix and use with other general purpose resin etc. In the case where the hole transport layer 3 is formed without using the charge transport polyether, the hole transport layer 3 is formed using these hole transport materials.

  In general formula (IX-6), n represents the integer of 10-100,000, Preferably the integer of 1000-50000 is represented.

  In the case of the layer structure of the organic EL element shown in FIG. 1, FIG. 2, or FIG. 3, the light emitting layer 5 is a compound that exhibits a high fluorescence quantum yield in the solid state as the light emitting material. When the light-emitting material is an organic low-molecular material, it is a condition that a favorable thin film can be formed by applying and drying a solution or dispersion containing a low-molecular material 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 a small organic molecule, a chelate-type organometallic complex, a polynuclear or condensed aromatic ring compound, a perylene derivative, a coumarin derivative, a styrylarylene derivative, a silole derivative, an oxazole derivative, an oxathiazole derivative, an oxadiazole derivative, 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 (X-1) to (X-17) are used, but are not limited thereto.
In the following structural formulas (X-1) to (X-17), Ar is a monovalent group or a divalent group having the same structure as Ar shown in the general formulas (I-1) and (I-2). Means a group, n and x each represent an integer of 1 or more, and y represents 0 or 1.

In addition, for the purpose of improving the durability of the organic EL element 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 such doping, an organic compound that is compatible with the light emitting material and does not interfere with the formation of a good thin film of the light emitting layer is used, preferably a DCM derivative, a quinacridone derivative, a rubrene derivative. And porphyrin-based compounds. As preferred specific examples, the following compounds (XI-1) to (XI-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 polyether is added to the light emitting material in an amount of 1% by weight or more. It may be formed by mixing and dispersing in the range of 50% by weight, or a charge transporting material other than the charge transporting polyether may be mixed and dispersed in the light emitting polymer in the range of 1% by weight to 50% by weight. Good.
Further, when the charge transporting polymer also has a light emitting property, it may be used as a light emitting material. In that case, the charge is added to the light emitting material for the purpose of further improving electrical properties and light emitting properties. A charge transport material other than the transportable polyether may be mixed and dispersed in the range of 1% by weight to 50% by weight.

  In the case of the layer configuration of the organic EL element shown in FIG. 4, the light-emitting layer 7 having charge transport capability is, for example, the charge transport property provided with a function (hole transport capability or electron transport capability) according to the purpose. The polyether is preferably made of a material in which the light emitting materials (X-1) to (X-17) are dispersed in an amount of 50% by weight or less as a light emitting material. In this case, 10 wt% to 50 wt% of a charge transport material other than the charge transport polyether may be dispersed in order to adjust the balance between holes and electrons injected into the organic EL element.

  As such a charge transport material, when adjusting the electron mobility, an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyrandioxide derivative, a fluorenylidenemethane derivative and the like are preferably used as the electron transport material. Can be mentioned. Preferable specific examples include the above compounds (VIII-1) to (VIII-3). In addition, an organic compound that does not exhibit a strong electron interaction with the charge transporting polyether is preferably used, and more preferably, the following compound (XII) 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. Although the said compound (IX-1)-(IX-6) is mentioned, A tetraphenylenediamine derivative is preferable from the compatibility with charge transportable polyether.

  In the case of the layer structure of the organic EL element shown in FIGS. 1 to 4, the back electrode 8 is made of a metal that can be vacuum-deposited and has a low work function for performing electron injection. Silver, indium and alloys thereof, metal halide compounds such as lithium fluoride and lithium oxide, and metal oxides.

Further, a protective layer may be provided on the back electrode 8 in order to prevent deterioration of the element due to moisture or oxygen. Specific materials for the protective layer include metals such as In, Sn, Pb, Au, Cu, Ag, Al, MgO, SIO ₂ , metal oxide of TIO ₂ building, polyethylene resin, polyurea resin, polyimide resin, etc. Resin. For forming the protective layer, a vacuum deposition method, a sputtering method, a plasma polymerization method, a CVD method, or a coating method can be applied.

  The organic EL elements shown in FIGS. 1 to 4 are 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. The buffer layer 3 is formed by vacuum deposition using the above-described material, or spin coating method on the transparent electrode 2 using a coating solution obtained by dissolving or dispersing this material in an organic solvent. The film can be formed by film formation using a dip method or the like.

Next, the hole transport layer 4, the light emitting layer 5, or the light emitting layer 7 having charge transporting ability is formed on the buffer layer 3 in accordance with the layer configuration of each organic EL element. Furthermore, each layer is further laminated | stacked on these layers one by one according to the layer structure of each organic EL element.
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 a vacuum vapor deposition method as described above, or using this material. Is formed by using a coating solution obtained by dissolving or dispersing in an organic solvent using a spin coating method, a dip method or the like.

The thicknesses of the hole transport layer 4, the light emitting layer 5 and the electron transport layer 6 to be formed are each preferably 0.1 μm or less, and particularly preferably in the range of 0.03 to 0.08 μm. The film thickness of the light emitting layer 7 having charge transporting capability is preferably about 0.03 to 0.2 μm.
The dispersion state of each of the materials (the charge transporting polyether, the light emitting material, etc.) may be a molecular dispersion state or a fine 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 fine particles, a ball mill, a sand mill, a paint shaker, an attritor, a homogenizer, an ultrasonic method, or the like can be used.
Finally, an organic EL element as shown in FIGS. 1 to 4 is obtained by forming a back electrode 8 on the light emitting layer 5, the electron transporting layer 6 or the light emitting layer 7 having charge transporting ability by a vacuum deposition method. be able to.

Such an organic EL device of the present invention can emit light by applying a direct current voltage of 1 to 200 mA / cm ² at a current density of 4 to 20 V between electrodes of a pair of anode and cathode, for example. .

  Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to the following examples.

Example 1
As a material for the buffer layer, a charge transporting polymer [the following exemplified compound (XIII)] (ionization potential = 5.0 eV, Mw = 6.98 × 10 ⁴ ) was prepared as a 5 wt% dichloroethane solution, It filtered with the tetrafluoroethylene (PTFE) filter. Using this solution, a 2 mm wide strip-shaped ITO electrode, which had been washed and dried, was applied on a glass substrate formed by etching, to form a buffer layer having a thickness of 0.05 μm by spin coating. After sufficiently drying, a charge transporting polyether [the following exemplified compound (XV) shown below is used as a hole transporting material together with 5% by weight of the following exemplified compound (XIV) (polyfluorene type) (Mw≈10 ⁵ ) as a light emitting material. )] (Mw = 8.65 × 10 ⁴ ) was prepared as a 5 wt% chlorobenzene solution, filtered through a 0.1 μm PTFE filter, and then applied onto the buffer layer by spin coating to form a film having a thickness of 0.03 μm. A light emitting layer was formed. After sufficiently drying, as an electron transporting material, a charge transporting polyether [the following exemplified compound (XVI)] (Mw = 7.20 × 10 ⁴ ) was prepared as a 5 wt% dichloroethane solution, and 0.1 μm After filtering with a PTFE filter, it was applied on the light emitting layer by a spin coating method to form an electron transport layer having a thickness of 0.03 μm. Finally, a Mg—Ag alloy was vapor-deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 2)
As a material for the buffer layer, a charge transporting polymer [the above exemplified compound (XIII)] (ionization potential = 5.0 eV, Mw = 6.98 × 10 ⁴ ) was prepared as a 5 wt% dichloroethane solution, It filtered with the tetrafluoroethylene (PTFE) filter. Using this solution, a 2 mm wide strip-shaped ITO electrode, which had been washed and dried, was applied on a glass substrate formed by etching, to form a buffer layer having a thickness of 0.05 μm by spin coating. After sufficiently drying, a charge transporting polyether [Exemplary Compound (XV)] (Mw = 8.65 × 10 ⁴ ) as a hole transporting material was prepared as a 5 wt% chlorobenzene solution, and 0.1 μm After filtering with a PTFE filter, the hole transport layer having a thickness of 0.01 μm was formed on the buffer layer by spin coating. After sufficiently drying, sublimated and purified Alq ₃ [Exemplary Compound (X-1)] as a luminescent material is put on a tungsten board and evaporated by a vacuum evaporation method, and a film thickness of 0.05 μm is formed on the hole transport layer. A light emitting layer was formed. The degree of vacuum at this time was 10 ⁻⁵ Torr, and the boat temperature was 300 ° C. Further, as an electron transporting material, a charge transporting polyether [Exemplary Compound (XVI)] (Mw = 7.20 × 10 ⁴ ) was prepared as a 5 wt% dichloroethane solution and filtered through a 0.1 μm PTFE filter. After that, an electron transport layer having a thickness of 0.03 μm was formed on the light emitting layer by spin coating. Finally, a Mg—Ag alloy was vapor-deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

(Example 3)
A charge transporting polymer [ionization potential = 5.0 eV, the exemplified compound (XIII)] (Mw = 6.98 × 10 ⁴ ) as a buffer layer material was prepared as a 5 wt% dichloroethane solution, It filtered with the tetrafluoroethylene (PTFE) filter. Using this solution, a 2 mm wide strip-shaped ITO electrode, which had been washed and dried, was applied on a glass substrate formed by etching, to form a buffer layer having a thickness of 0.05 μm by spin coating. After sufficiently drying, a charge transporting polyether [the following exemplified compound (XV)] (Mw = 8.65 × 10 ⁴ ) as a hole transporting material was prepared as a 5 wt% chlorobenzene solution, and 0.1 μm After filtering with a PTFE filter, the hole transport layer having a thickness of 0.01 μm was formed on the buffer layer by spin coating. After sufficiently drying, sublimated and purified Alq ₃ [Exemplary Compound (X-1)] as a luminescent material is put on a tungsten board and evaporated by a vacuum evaporation method, and a film thickness of 0.05 μm is formed on the hole transport layer. A light emitting layer was formed. The degree of vacuum at this time was 10 ⁻⁵ Torr, and the boat temperature was 300 ° C. Finally, a Mg—Ag alloy was vapor-deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

Example 4
As a material for the buffer layer, a charge transporting polymer [the above exemplified compound (XIII)] (ionization potential = 5.0 eV, Mw = 6.98 × 10 ⁴ ) was prepared as a 5 wt% dichloroethane solution, It filtered with the tetrafluoroethylene (PTFE) filter. Using this solution, a 2 mm wide strip-shaped ITO electrode, which had been washed and dried, was applied on a glass substrate formed by etching, to form a buffer layer having a thickness of 0.05 μm by spin coating. After sufficiently drying, 0.5 parts by weight of charge transporting polyether [Exemplary Compound (XVI)] (Mw = 8.65 × 10 ⁴ ) as a charge transporting material and the following exemplified compound as a light emitting polymer 0.1 parts by weight of (XVII) (PPV system) is mixed, adjusted as a 10 wt% chlorobenzene solution, filtered through a 0.1 μm PTFE filter, applied onto the buffer layer by spin coating, and the film thickness is 0 A light emitting layer having a charge transport ability of 0.05 μm was formed. Finally, a Mg—Ag alloy was vapor-deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the formed organic EL element was 0.04 cm ² .

( Reference Example 5)
As a buffer layer, Baytron P (manufactured by Bayer Co., Ltd .: Polyethylenedioxide thiophene [the following compound (III) ionization potential = 5.1-5.2 eV,) and a polymer mixed water dispersion of polystyrene sulfonic acid] The same as in Example 1 except that a 2 mm wide strip-shaped ITO electrode that had been washed and dried was applied by spin coating on a glass substrate formed by etching to form a buffer layer having a thickness of 0.05 μm. Thus, an element was produced.

( Reference Example 6)
As a buffer layer, Baytron P (manufactured by Bayer Co., Ltd .: polyethylenedioxide thiophene [polymerization mixture aqueous dispersion of the above exemplified compound (III) ionization potential = 5.1-5.2 eV,) and polystyrene sulfonic acid] The same as in Example 2, except that a 2 mm wide strip-shaped ITO electrode that was washed and dried was applied by spin coating on a glass substrate formed by etching to form a buffer layer having a thickness of 0.05 μm. Thus, an element was produced.

( Reference Example 7)
As a buffer layer, Baytron P (manufactured by Bayer Co., Ltd .: polyethylenedioxide thiophene [polymerization mixture aqueous dispersion of the above exemplified compound (III) ionization potential = 5.1-5.2 eV,) and polystyrene sulfonic acid] The same as Example 3 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that had been used and washed and then dried by etching. Thus, an element was produced.

( Reference Example 8)
As a buffer layer, Baytron P (manufactured by Bayer Co., Ltd .: polyethylenedioxide thiophene [polymerization mixture aqueous dispersion of the above exemplified compound (III) ionization potential = 5.1-5.2 eV,) and polystyrene sulfonic acid] The same as Example 4 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that had been used and washed and dried. Thus, an element was produced.

( Reference Example 9)
The following exemplified compound (XVIII) [MTDATA (4,4 ′, 4 ”-tris (3-methylphenylphenylamino) triphenylamine), ionization potential = 5.1 eV, compound based on the exemplified compound (IV) as a buffer layer A 5 wt% chlorobenzene solution was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and this solution was used to wash and dry the strip-shaped ITO having a width of 2 mm. An element was fabricated in the same manner as in Example 1 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate on which an electrode was formed by etching by spin coating.

( Reference Example 10)
As the buffer layer, the exemplified compound (XVIII) [MTDATA (4,4 ′, 4 ”-tris (3-methylphenylphenylamino) triphenylamine), ionization potential = 5.1 eV, compound based on the exemplified compound (IV) A 5 wt% chlorobenzene solution was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and this solution was used to wash and dry the strip-shaped ITO having a width of 2 mm. An element was fabricated in the same manner as in Example 2 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate on which an electrode was formed by etching by spin coating.

( Reference Example 11)
As the buffer layer, the exemplified compound (XVIII) [MTDATA (4,4 ′, 4 ”-tris (3-methylphenylphenylamino) triphenylamine), ionization potential = 5.1 eV, compound based on the exemplified compound (IV) A 5 wt% chlorobenzene solution was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and this solution was used to wash and dry the strip-shaped ITO having a width of 2 mm. An element was fabricated in the same manner as in Example 3 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate formed by etching an electrode by spin coating.

( Reference Example 12)
As the buffer layer, the exemplified compound (XVIII) [MTDATA (4,4 ′, 4 ”-tris (3-methylphenylphenylamino) triphenylamine), ionization potential = 5.1 eV, compound based on the exemplified compound (IV) A 5 wt% chlorobenzene solution was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and this solution was used to wash and dry the strip-shaped ITO having a width of 2 mm. An element was fabricated in the same manner as in Example 4 except that a buffer layer having a thickness of 0.05 μm was formed on a glass substrate on which an electrode was formed by etching by spin coating.

( Reference Example 13)
Vacuum deposition is performed on a glass substrate on which a 2 mm-wide strip-shaped ITO electrode formed by etching a charge transporting material (ionization potential = 4.8 eV) represented by the exemplary compound (V) as a buffer layer is dried after washing. A device was fabricated in the same manner as in Example 1 except that a buffer layer having a film thickness of 0.05 μm was formed by vapor deposition.

( Reference Example 14)
Vacuum deposition is performed on a glass substrate on which a 2 mm-wide strip-shaped ITO electrode formed by etching a charge transporting material (ionization potential = 4.8 eV) represented by the exemplary compound (V) as a buffer layer is dried after washing. A device was fabricated in the same manner as in Example 2 except that a buffer layer having a thickness of 0.05 μm was formed by vapor deposition.

( Reference Example 15)
Vacuum deposition is performed on a glass substrate on which a 2 mm-wide strip-shaped ITO electrode formed by etching a charge transporting material (ionization potential = 4.8 eV) represented by the exemplary compound (V) as a buffer layer is dried after washing. A device was fabricated in the same manner as in Example 3 except that a buffer layer having a thickness of 0.05 μm was formed by vapor deposition.

( Reference Example 16)
Vacuum deposition is performed on a glass substrate on which a 2 mm-wide strip-shaped ITO electrode formed by etching a charge transporting material (ionization potential = 4.8 eV) represented by the exemplary compound (V) as a buffer layer is dried after washing. A device was fabricated in the same manner as in Example 4 except that a buffer layer having a thickness of 0.05 μm was formed by vapor deposition.

(Comparative Example 1)
A device was fabricated in the same manner as in Example 1 except that the buffer layer was not formed and the light emitting layer was directly formed on the glass substrate on which the ITO electrode was formed.

(Comparative Example 2)
A device was fabricated in the same manner as in Example 2, except that the buffer layer was not formed and the hole transport layer was directly formed on the glass substrate on which the ITO electrode was formed.

(Comparative Example 3)
A device was fabricated in the same manner as in Example 3 except that the buffer layer was not formed and the hole transport layer was directly formed on the glass substrate on which the ITO electrode was formed.

(Comparative Example 4)
A device was fabricated in the same manner as in Example 4 except that a buffer layer was not formed and a light emitting layer having a charge transport capability was directly formed on a glass substrate on which an ITO electrode was formed.

(Comparative Example 5)
When a charge transporting polyether [the above exemplified compound (XV)] is used as a hole transporting material in the light emitting layer, a charge transporting polymer having a vinyl skeleton of the following exemplified compound (XIX) [Mw = 5. 46 × 10 ⁴ (converted to styrene)] and sublimation-purified oxadiazole derivative [above exemplified compound (VIII) instead of charge transporting polyether [above exemplified compound (XVI)] as an electron transporting material. -1)] is placed on a tungsten board and deposited by a vacuum deposition method (the degree of vacuum during deposition was 10 ⁻⁵ Torr and the boat temperature was 300 ° C.), and the film thickness was 0 on the light emitting layer. A device was fabricated in the same manner as in Example 1 except that a 0.03 μm electron transport layer was formed.

(Comparative Example 6)
When a charge transporting polyether (XV) is used as a hole transporting material, a charge transporting polymer having a vinyl skeleton of the above exemplary compound (XIX) [Mw = 5.46 × 10 ⁴ (in terms of styrene)] A device was fabricated in the same manner as in Example 3 except that the change was made.

(Comparative Example 7)
When a charge transporting polyether [the above exemplified compound (XV)] is used as the hole transporting material, a charge transporting polymer having a polycarbonate skeleton of the following exemplified compound (XX) [Mw = 7.83 × 10 ^4]. A device was produced in the same manner as in Example 3 except that the value was changed to (styrene conversion).

(Comparative Example 8)
Instead of the charge transporting polyether [the above exemplified compound (XV)] as the hole transporting material, a charge transporting polymer having the vinyl skeleton [the above exemplified compound (XIX), Mw = 5.46 × 10 ⁴ (styrene) Conversion)) to form a hole transport layer having a thickness of 0.01 μm on the buffer layer by spin coating, and a charge transporting polyether [the above exemplified compound (XVI) as an electron transporting material) ] Instead of sublimation-purified oxadiazole derivative (Exemplary Compound (VIII-1)), this was put on a tungsten board and deposited by vacuum deposition (the degree of vacuum during deposition was 10 ⁻⁵ Torr). The boat temperature was 300 ° C.), and a device was fabricated in the same manner as in Reference Example 6 except that an electron transport layer having a thickness of 0.03 μm was formed on the light emitting layer.

(Comparative Example 9)
As the hole transporting material, instead of the charge transporting polyether [the above exemplified compound (XV)], a charge transporting polymer having a vinyl skeleton [the above exemplified compound (XIX), Mw = 5.46 × 10 ⁴ ( Is applied to the buffer layer by a spin coating method to form a hole transport layer having a thickness of 0.01 μm, and a charge transporting polyether [the above exemplified compound (XV) as an electron transporting material is also used. ], Using a sublimation-purified oxadiazole derivative (Exemplary Compound (VIII-1)), which is put on a tungsten board and deposited by vacuum deposition (the degree of vacuum during deposition is 10 ⁻⁵ Torr, The boat temperature was 300 ° C.), and a device was fabricated in the same manner as in Reference Example 10 except that an electron transport layer having a thickness of 0.03 μm was formed on the light emitting layer.

(Comparative Example 10)
As a hole transporting material, instead of the charge transporting polyether [the above exemplified compound (XV)], a charge transporting polymer having the polycarbonate skeleton [the above exemplified compound (XX), Mw = 7.83 × 10 ⁴ ( Is applied to the buffer layer by a spin coating method to form a hole transport layer having a thickness of 0.01 μm, and a charge transporting polyether [the above exemplified compound (XVI) as an electron transporting material) ], Using a sublimation-purified oxadiazole derivative (Exemplary Compound (VIII-1)), which is put on a tungsten board and deposited by vacuum deposition (the degree of vacuum during deposition is 10 ⁻⁵ Torr, The boat temperature was 300 ° C.), and a device was fabricated in the same manner as in Reference Example 14 except that an electron transport layer having a thickness of 0.03 μm was formed on the light emitting layer.

(Evaluation)
The organic EL device fabricated 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 when the light was emitted, the maximum luminance, and the drive current density at the maximum luminance were evaluated. The results are shown in Table 1.
Moreover, the light emission lifetime of the organic EL element was measured in dry nitrogen. In the evaluation of the light emission 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. The device lifetime at this time is also shown in Table 1.

As can be seen from Table 1, the organic EL devices of the present invention shown in Examples and Reference Examples are represented by the general formula (I-1) and the charge transporting polymer having an ionization potential and charge mobility suitable for the organic EL device. A charge transporting polyether comprising a repeating structural unit containing at least one selected from the structure represented by (I-2) as a partial structure is applied, and further has a charge injection property in contact with the anode (ITO electrode) By forming the buffer layer, the charge injection property and the charge balance were improved, and Comparative Examples 1 to 4 in which no buffer layer was provided, and Comparative Example 5 using a charge transporting compound different from the above charge transporting polyether As a result, it was found that the organic EL device showed more stable, high luminance, and high efficiency characteristics than the organic EL devices of -6.
In addition, as can be seen from a comparison between Examples 1 and 3 and Comparative Examples 5 to 6, even when a buffer layer that does not contain a low molecular component causing bleeding is provided, as an electron transport layer or a hole transport layer It was found that Examples 1 and 3 using the charge transporting polyether used in the present invention were superior in device lifetime and emission luminance.
Furthermore, in the case where a buffer layer containing a low molecular component that causes bleeding in Reference Examples 6, 10, and 14 and Comparative Examples 7 to 9 is provided, an electron transport layer or a hole transport provided on the buffer layer It was found that Reference Examples 5, 9, and 13 using the charge transporting polyether used in the present invention as the layer had better device lifetime and light emission luminance. This is considered to be because bleeding from the buffer layer was suppressed by the presence of the charge transporting polyether contained in the layer provided on the buffer layer. In addition, it was found that no pinhole or peeling defect occurred during film formation in any of the examples and reference examples .
Furthermore, the organic EL device of the present invention can form a good thin film by using a spin coating method, a dip method or the like at the time of production, so that there are few defects such as pinholes, it is easy to increase the area, and excellent Durability and light emission characteristics can be obtained.

It is typical sectional drawing which showed an example of the organic electroluminescent element in this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element in this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element in this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element in this invention.

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 a carrier transport ability 8 ... Back electrode

Claims (9)

It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer is composed of at least a light emitting layer, a buffer layer, and an electron transport layer. ,
At least one of the light emitting layer and the electron transporting layer contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light emitting layer, and is represented by the following general formulas (II-1) to (II-4) as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from structural units.

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A C1-C6 bivalent linear hydrocarbon group or a C2-C10 branched hydrocarbon group is represented, and m and k each independently represent 0 or 1. ]

[In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

(In the general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, m and l each independently represent 0 or 1, and T represents 1 carbon atom. Represents a divalent linear hydrocarbon of ˜6 or a branched hydrocarbon of 2 to 10 carbon atoms.) It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer comprises at least a light emitting layer, a buffer layer, a hole transport layer, and an electron Consists of a transport layer,
At least one of the hole transport layer and the electron transport layer contains at least one charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI): A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by:

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A C1-C6 bivalent linear hydrocarbon group or a C2-C10 branched hydrocarbon group is represented, and m and k each independently represent 0 or 1. ]

[In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

(In the general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, m and l each independently represent 0 or 1, and T represents 1 carbon atom. Represents a divalent linear hydrocarbon of ˜6 or a branched hydrocarbon of 2 to 10 carbon atoms.) It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent, and the organic compound layer is composed of at least a light emitting layer, a buffer layer, and a hole transport layer And
At least one of the hole transport layer and the light emitting layer contains at least one charge transport polyether, and the charge transport polyether is a charge transport polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the hole transport layer, and the following general formulas (II-1) to (II-4) are used as one or more kinds of charge injection materials. An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by:

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A C1-C6 bivalent linear hydrocarbon group or a C2-C10 branched hydrocarbon group is represented, and m and k each independently represent 0 or 1. ]

[In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

(In the general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, m and l each independently represent 0 or 1, and T represents 1 carbon atom. Represents a divalent linear hydrocarbon of ˜6 or a branched hydrocarbon of 2 to 10 carbon atoms.) It is composed of an organic compound layer sandwiched between a pair of anodes and cathodes, at least one of which is transparent or translucent. The organic compound layer is composed only of a light emitting layer and a buffer layer, and the light emitting layer is charged. A light emitting layer having transport ability,
The light emitting layer having the charge transporting capability contains at least one kind of charge transporting polyether, and the charge transporting polyether is a charge transporting polyether represented by the following general formula (VI). A charge transporting polyether having a repeating unit containing at least one selected from the structures represented by (I-1) and (I-2) as a partial structure;
The buffer layer is provided in contact with the anode between the anode and the light-emitting layer having charge transport ability , and the following general formulas (II-1) to (II) are used as one or more kinds of charge injection materials. 4) An organic electroluminescent device comprising a charge transporting polymer having at least one selected from the structural units represented by 4).

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted monovalent aromatic group, X represents a substituted or unsubstituted divalent aromatic group, and T represents A C1-C6 bivalent linear hydrocarbon group or a C2-C10 branched hydrocarbon group is represented, and m and k each independently represent 0 or 1. ]

[In the general formula (VI), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, substituted or unsubstituted. An aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 3 to 5000. ]

(In the general formulas (II-1) to (II-4), Ar represents a substituted or unsubstituted monovalent aromatic group, m and l each independently represent 0 or 1, and T represents 1 carbon atom. Represents a divalent linear hydrocarbon of ˜6 or a branched hydrocarbon of 2 to 10 carbon atoms.) The organic electroluminescence device according to claim 1 , 2, 3, or 4 , wherein at least one ionization potential of the charge injection material is 5.2 eV or less. The organic electroluminescent element according to claim 1 , wherein the light emitting layer includes a charge transporting material. The organic electroluminescent element according to claim 2 , wherein the light emitting layer contains a charge transporting material. The organic electroluminescent device according to claim 3 , wherein the light emitting layer includes a charge transporting material. The organic electroluminescent element according to claim 4 , wherein the light emitting layer having the charge transporting capability contains a charge transporting material.

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