JP4956885B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescent device (hereinafter referred to as “organic EL device”), and more particularly to an organic electroluminescent device 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. Currently, those using inorganic phosphors are the mainstream, but they have problems such as high manufacturing costs and insufficient brightness because an AC voltage of 200 V or higher is required for driving.
In contrast, 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 below). 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 functionally 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 / It has been reported that high luminance of m ² or more can be obtained (see Non-Patent Document 2 below), and since then, 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) Because it is driven at a high current density of several mA / cm ² , it generates a large amount of Joule heat. 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) Thin film with a thickness of 0.1 μm or less is formed in multiple vapor deposition processes of low molecular weight organic compounds, so pinholes are likely to occur and the film thickness is controlled under strictly controlled conditions to obtain sufficient performance. It is necessary to do. Therefore, productivity is low and it is difficult to increase the area.
(3) The light-emitting material uses light emitted from an excited singlet state, that is, fluorescence. However, the generation ratio of excitons in the excited singlet state and excited triplet state generated by recombination of holes and electrons in the light emitting layer is 1: 3 from the spin statistic rule based on quantum mechanics. The upper limit of the internal quantum efficiency of light emission in EL is theoretically 25%.

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 Non-Patent Document 3 below), or a side chain of polyphosphazene. An EL device using a polymer in which triphenylamine is introduced (see Non-Patent Document 4 below) 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 a single-layer organic EL device that can shorten the process is underway, and conductive polymers such as poly (p-phenylene vinylene) are used. Devices (see Non-Patent Document 5 below) and devices in which an electron transport material and a fluorescent dye are mixed in hole transporting polyvinyl carbazole (see Non-Patent Document 6 below) have been proposed. However, the luminance, luminous efficiency, etc. are still not as good as those of the stacked organic EL device using the organic low molecular weight compound. Furthermore, from the viewpoint of manufacturing methods, wet coating methods are being 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 below). 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.

Next, in order to solve the problem shown in (3), an excited triplet state having a high probability of exciton generation, that is, a phosphorescent light emitting material is used. An element using a platinum complex (see Non-Patent Document 9 below) was first proposed as a phosphorescent light-emitting material, and an external quantum efficiency of 7.5% (external extraction efficiency was 20% by using a phosphorescent iridium complex). Assuming that the internal quantum efficiency is 37.5%), it is shown that it is possible to exceed the value of the external quantum efficiency of 5%, which has been conventionally set as the upper limit (see Non-Patent Document 10 below). However, in actual use, it is necessary to dope a specific low molecular weight organic compound that is a host compound and use it, and there are problems (1) and (2) similar to those of a light emitting material by fluorescence.
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 31p-g-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) Nature, Vol.395, 151 (1998) Applied Physics Letter, Vol.75, 4 (1999), WO00 / 70655

An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide an organic EL device that has sufficient luminance, is excellent in stability and durability, can be increased in area, and can be easily manufactured.

As a result of intensive studies on charge transport materials to achieve the above object, the charge transport polyether represented by the following general formula (II) has charge injection characteristics, charge mobility, and thin film formation ability suitable for an organic EL device. In addition, by combining the following compound (VIII) that emits light by transition from the excited triplet state of the electron energy level to the ground state or from the ground state via the excited triplet state, The present invention has been completed by finding that the device has excellent luminous efficiency and high productivity.
That is, the organic electroluminescent element of the present invention is
<1> In an electroluminescent device composed of one or a plurality of organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent, at least one of the organic compound layers is at least one kind It contains a charge transporting polyether represented by the following general formula (II), and at least one of the organic compound layers passes through a transition from an excited triplet state of an electronic energy level to a ground state or an excited triplet state. It is an organic electroluminescent element characterized by containing the following compound (VIII) light-emitted by the transition to the ground state.
In (lower SL one general formula (II), the structure represented by the following general formula (II-1) represents a structure selected from the following formula (VII-1) ~ formula (VII-3), R is hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, p is represents an integer of 5 to 5,000, the formula (VII-1) ~ formula (VII-3 N in ) means p in the general formula (II).

<2> The organic compound layer is composed of at least a light emitting layer and an electron transport layer, and at least one of the light emitting layer and the electron transport layer is at least one charge transporting polyether represented by the general formula (II). The organic electroluminescent device according to <1>, wherein the light emitting layer contains the compound (VIII).
<3> The organic electroluminescent element according to <2>, wherein the light emitting layer contains a charge transporting material.
<4> The organic compound layer is composed of at least a hole transport layer, a light emitting layer and an electron transport layer, and at least one or both of the hole transport layer and the electron transport layer is represented by the general formula (II). <1> The organic electroluminescent element according to <1>, wherein the organic electroluminescent element contains at least one kind of charge transporting polyether, and the light emitting layer contains the compound (VIII).
<5> The organic electroluminescent element according to <4>, wherein the light emitting layer contains a charge transporting material.
<6> The organic compound layer includes at least a hole transport layer and a light emitting layer, and at least one of the hole transport layer and the light emitting layer includes at least a charge transporting polyether represented by the general formula (II). <1> The organic electroluminescence device according to <1>, wherein the organic electroluminescence device comprises one type, and the light emitting layer contains the compound (VIII).
<7> The organic electroluminescent element according to <6>, wherein the light emitting layer contains a charge transporting material.
<8> The organic compound layer is composed of only one light emitting layer having charge transporting ability, and the light emitting layer includes at least one charge transporting polyether represented by the general formula (II), and the compound ( VIII), and the organic electroluminescent device according to <1>.
<9> The organic electroluminescent element according to <8>, wherein the light emitting layer contains a charge transporting material.
The charge transporting polyether represented by the general formula (II) used in the organic EL device of the present invention has an ionization potential and charge mobility suitable for the organic EL device, and has good solubility in a solvent. Therefore, it is possible to easily form a good thin film (organic compound layer) using a spin coating method, a dip method or the like. In addition, in the organic EL device of the present invention, the compound (VIII) that emits light by a transition from an excited triplet state of an electronic energy level to a ground state or a transition to a ground state via an excited triplet state ( Hereinafter, since this compound is also referred to as a “light-emitting low molecular weight compound”), the use of the charge transporting polyether exhibits a sufficiently high luminance and a low driving current density. Therefore, the organic EL device of the present invention has sufficient luminance, is excellent in stability and durability, can have a large area, is easy to manufacture, and can overcome the disadvantages of the conventional methods as described above. it can.
Moreover, the solubility with respect to a solvent is controllable by changing the partial structure and substituent in general formula (I-1) or (I-2) of charge-transporting polyether. Therefore, when forming multiple organic compound layers by coating, it is possible to control the solubility of the charge transporting polyether used for the upper and lower layers so that the lower layer is not damaged when the upper layer is applied. It is.
Furthermore, since the glass transition point of the charge transporting polyether can be controlled, it is easy to produce the charge transporting polyether for producing an organic compound layer that does not crystallize even when a thermal history is applied.

The organic EL device of the present invention is an electroluminescent device composed of one or a plurality of organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent. At least one of the organic compound layers There contains at least one charge-transporting polyether represented by the general formula (II), further organic at least excited triplet state even is electron energy levels of the compound layer to the ground state transition or excited triplet The compound (VIII) which emits light by transition to the ground state via the term state is contained .

In the 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 group having 2 to 10 aromatics, a substituted or unsubstituted aromatic group having 2 to 10 aromatic monovalents. A condensed ring aromatic hydrocarbon group, a substituted or unsubstituted monovalent aromatic heterocyclic group, or a substituted or unsubstituted monovalent aromatic group containing at least one aromatic heterocyclic ring is represented.

Here, in the general formulas (I-1) and (I-2), a polynuclear aromatic hydrocarbon group and a condensed ring aroma selected as one of substituted or unsubstituted monovalent aromatic groups (Ar) The number of aromatic rings constituting the aromatic hydrocarbon group is not particularly limited, but those having 2 to 5 aromatic rings are preferred. The condensed ring aromatic hydrocarbon in the condensed ring aromatic hydrocarbon group is preferably a fully condensed ring aromatic hydrocarbon.
In the present invention, the polynuclear aromatic hydrocarbon group and the condensed ring aromatic hydrocarbon group specifically mean a polycyclic aromatic group defined below.
That is, the polynuclear aromatic hydrocarbon in the “polynuclear aromatic hydrocarbon group” means that there are two or more aromatic rings composed of carbon and hydrogen, and these aromatic rings are separated by a carbon-carbon single bond. Represents bonded hydrocarbons. Specific examples of the polynuclear aromatic hydrocarbon include biphenyl and terphenyl.
Further, the condensed ring aromatic hydrocarbon in the “fused ring aromatic hydrocarbon group” includes two or more aromatic rings composed of carbon and hydrogen, and these aromatic rings are adjacent to each other in a pair. Represents a hydrocarbon sharing a carbon atom to be bonded. Specific examples of the condensed ring aromatic hydrocarbon include naphthalene, anthracene, phenanthrene, fluorene and the like.

Further, in the general formulas (I-1) and (I-2), the aromatic heterocycle in the “aromatic heterocyclic group” selected as one of the substituted or unsubstituted monovalent aromatic groups (Ar). The ring represents an aromatic ring including elements other than carbon and hydrogen. The number of atoms (Nr) constituting the ring skeleton of the aromatic heterocyclic ring is preferably Nr = 5 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 preferable, and one or more kinds of heteroatoms are included in the ring skeleton. 1 or 2 or more may be contained. In particular, as a heterocyclic ring having a 5-membered ring structure, thiophene, thiofin and furan, a heterocyclic ring in which the carbons at the 3-position and 4-position thereof are further substituted with nitrogen, and pyrrole and carbons at the 3-position and 4-position are further added. Preferred examples include a heterocyclic ring substituted with nitrogen, and preferred examples of the heterocyclic ring having a 6-membered ring structure include pyridine.
In addition, the aromatic heterocyclic group may be further substituted with an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, or a terphenyl group, and the aromatic heterocyclic group may be the same or different aromatic heterocyclic group. The ring group may be further substituted.

  Further, in the general formulas (I-1) and (I-2), an “aromatic group including an aromatic heterocycle” selected as one of substituted or unsubstituted monovalent aromatic groups (Ar) Represents a group obtained by substituting the aromatic heterocyclic group for the phenyl group, polynuclear aromatic hydrocarbon group or condensed ring aromatic hydrocarbon group.

  These groups may be either all composed of a conjugated system or partially composed of a non-conjugated system, but are all composed of a conjugated system in terms of charge transportability and luminous efficiency. Those are preferred.

In addition to the substituents as described above, the phenyl group, polynuclear aromatic hydrocarbon group, condensed ring aromatic hydrocarbon group, aromatic heterocyclic group, or aromatic group containing an aromatic heterocyclic ring represents hydrogen. Substituents such as atoms, alkyl groups, alkoxy groups, phenoxy groups, aryl groups, aralkyl groups, substituted amino groups, and halogen atoms may be substituted.
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 the alkoxyl group, those having 1 to 10 carbon atoms are preferable, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group.
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.
Examples of the halogen atom include chlorine, bromine and the like.

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 group having 2 to 10 aromatics, a substituted or unsubstituted aromatic group having 2 to 10 aromatic divalents. It represents a condensed ring aromatic hydrocarbon group, a substituted or unsubstituted divalent aromatic heterocyclic group, or a substituted or unsubstituted divalent aromatic group containing at least one kind of aromatic heterocyclic ring.
Here, “polynuclear aromatic hydrocarbon” in the “divalent polynuclear aromatic hydrocarbon group”, “divalent condensed ring aromatic hydrocarbon group” and “divalent aromatic heterocyclic group”, “condensation” `` Ring aromatic hydrocarbon '' and `` aromatic heterocycle '' are synonymous with `` polynuclear aromatic hydrocarbon '', `` fused ring aromatic hydrocarbon '' and `` aromatic heterocycle '' described in the description of Ar, The specific example is also the same.

  In addition, the “substituted or unsubstituted divalent aromatic group containing an aromatic heterocycle” refers to the “aromatic group containing an aromatic heterocycle (monovalent)” selected as one of Ar. This refers to one that has a single bond. It is preferable that the other bond is from an aromatic heterocycle.

  These divalent aromatic groups may be either all conjugated or partly non-conjugated, but are all conjugated in terms of charge transport and luminous efficiency. Those composed of a system are preferred.

  Examples of the substituent substituted with the “divalent aromatic group” include the same substituents as those substituted with Ar.

  In general formulas (I-1) and (I-2), k, l and m represent 0 or 1, and T is a divalent straight chain having 1 to 6 carbon atoms, preferably 2 to 6 carbon atoms. A hydrocarbon group or a divalent branched hydrocarbon group having 2 to 10 carbon atoms, preferably 3 to 7 carbon atoms is shown. The specific structure of T is shown below.

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

In the general formula (II), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and two or more types of structures A are contained in one polymer. May be included.
In the general formula (II), 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.
The aryl group preferably has 6 to 20 carbon atoms, for example, a phenyl group, Ru toluyl group and the like.
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 (II), p representing the degree of polymerization is in the range of 5 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, preferably in the range of 10,000 to 300,000.

  For the charge transporting polyether of the present invention, a hole transporting monomer represented by the following structural formula (III-1) or (III-2) is used, for example, 4th edition Experimental Chemistry Course Vol. 28 (Maruzen, 1992), etc. It can synthesize | combine by making it superpose | polymerize by the well-known method described in 1). In the structural formula (III-1) or (III-2), Ar, X, T, k, and l are Ar, X, T in the general formula (I-1) or (I-2). Synonymous with k, l.

That is, the hole transporting polyether represented by the general formula (II) can be synthesized as follows.
1) The charge transporting polymer is obtained by a method in which a charge transporting compound (charge transporting monomer) having two hydroxyalkyl groups in the general formulas (III-1) and (III-2) is subjected to heat dehydration condensation. Can be synthesized. In this case, it is desirable that the charge transporting monomer is heated and melted without a solvent and reacted under reduced pressure in order to promote a polymerization reaction due to elimination of water. When a solvent is used, a solvent azeotroped with water, for example, trichloroethane, toluene, chlorobenzene, dichlorobenzene, nitrobenzene, 1-chloronaphthalene, etc. is effective for removing water, and the charge transporting monomer 1 It is used in the range of 1 to 100 equivalents, preferably 2 to 50 equivalents, relative to 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) The charge transporting polymer can be synthesized by a dehydration condensation method using a protonic acid such as p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, trifluoroacetic acid, or a Lewis acid such as zinc chloride as an acid catalyst. . In this case, the acid catalyst is used in the range of 1 to 1/10000 to 1/10 equivalent, preferably 1/1000 to 1/50 equivalent, relative to 1 equivalent of the 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) The above hole transporting polymers are alkyl isocyanates such as cyclohexyl isocyanate, alkyl isocyanates such as cyclohexyl cyanide, cyanides such as p-tolyl cyanate and 2,2-bis (4-cyanatophenyl) propane. It can also be synthesized by a method using a condensing agent such as acid ester, dichlorohexylcarbodiimide (DCC), or 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 from the room temperature to the boiling point of a solvent. Of the synthesis methods 1), 2) and 3), the synthesis method 1) or 3) is preferred because isomerization and side reactions are unlikely to occur. In particular, the synthesis method 3) is more preferable because the reaction conditions are milder.

When the solvent is not used after completion of the reaction, the reaction product is dissolved in a soluble solvent. In the case of using a solvent, the reaction solution is dropped as it is in a poor solvent in which a charge transporting polymer such as methanol or ethanol or a charge transporting polymer such as acetone is difficult to dissolve, to precipitate the charge transporting polymer, and to transport the charge. After separating the functional polymer, it is thoroughly washed with water or an organic solvent and dried. 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 carried out with efficient stirring using a mechanical stirrer or the like.
The solvent for dissolving the charge transporting polymer in the reprecipitation treatment 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 kinds of charge transporting monomers, preferably 2 to 5 kinds, more preferably 2 to 3 kinds. By copolymerizing different kinds of charge transporting monomers, it is possible to control electrical characteristics, film formability, and solubility.

  If the degree of polymerization 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 is lowered and the processability is deteriorated. The range is set, preferably 10 to 3000, more preferably 15 to 1000.

The terminal group of the charge transporting polymer may be a hydroxyl group, i.e., 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 physical properties. For example, the terminal hydroxyl group can be alkyl etherified, aryl etherified or aralkyl etherified with alkyl sulfate, alkyl iodide or the like. Specific reagents can be arbitrarily selected from dimethyl sulfate, diethyl sulfate, methyl iodide, ethyl iodide and the like.
The reagent is used in an amount of 1 to 3 equivalents, preferably 1 to 2 equivalents, based on the terminal hydroxyl group. 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., and 1 to 3 equivalents relative to the terminal hydroxyl group, Preferably it is used in the range of 1 to 2 equivalents. The reaction temperature can be from 0 ° C. to the boiling point of the solvent used. In addition, the solvent used 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 may 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. -Toluoyl chloride, m-toluoyl chloride, p-toluoyl chloride, etc. are mentioned, 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, but the base catalyst can be arbitrarily selected from pyridine, dimethylaminopyridine, trimethylamine, triethylamine, etc., and is 1 to 3 equivalents, preferably 1 to 2 equivalents, relative to the acid chloride. Use within the range. Examples of the solvent used at that time include benzene, toluene, methyl chloride, tetrahydrofuran, and methyl ethyl ketone. The reaction can be carried out from 0 ° C. to the boiling point of the solvent. Preferably, it is carried out in the range of 0 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 tert-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 i-propyl ester, isocyanic acid m-tolyl ester, isocyanic acid p-tolyl ester, It can be arbitrarily selected from isocyanic acid 1-naphthyl ester 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 here 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. If the reaction is difficult to proceed, add a metal compound such as dibutyltin (II) dilaurate, tin (II) octylate or lead naphthenate, or a tertiary amine such as triethylamine, trimethylamine, pyridine or dimethylaminopyridine as a catalyst. You can also.

  Specific examples of the charge transporting polyether in the present invention are shown below, but are not limited thereto.

  The light-emitting low-molecular compound of the present invention includes a compound that emits light by transition from an excited triplet state of an electronic energy level to a ground state in a solid state or from a ground state via an excited triplet state. Used. The compound that emits light by transition to the ground state via the excited triplet state here refers to the excitation of the portion corresponding to the phosphorescent first organic compound disclosed in JP-A-2002-050483. A substance composed of two types of components in which energy transfer from the triplet state to the excited triplet state of the portion corresponding to the fluorescent organic second organic compound occurs and fluorescence emission from the second organic compound portion occurs. .

  The value of the quantum efficiency of the excited triplet state in the phosphorescent part is preferably 0.1 or more, more preferably 0.3 or more, and still more preferably 0.5 or more. Examples of compounds having high quantum efficiency in the excited triplet state that can be applied to these phosphorescent moieties include metal complexes, but are not limited thereto.

  Specific examples of the metal complex include (1) transition metal complexes such as iridium complexes and platinum complexes and derivatives thereof, and (2) rare earth metal complexes. These are preferable in that they have an excited triplet state that is relatively stable even at high temperatures. Moreover, it is preferable also from the point which can be complexed easily by coordinating the polymer which has a functional group with coordination ability to a transition metal atom so that it may mention later.

  As transition metals used in the above transition metal complexes, in the periodic table, the first transition element series is Sc from atomic number 21 to Zn of atomic number 30, and the second transition element series is from Y of atomic number 39 to atoms. Up to Cd of number 48, the third transition element series includes from Hf of atomic number 72 to Hg of atomic number 80. In addition, the rare earth metal used in the rare earth metal complex includes La of atomic number 57 to Lu of atomic number 71 in the periodic table.

  The luminescent moiety in the present invention is nonionic. This is because, when the luminescent portion is ionic, electrochemiluminescence occurs when a voltage is applied to the luminescent layer including the luminescent portion, and the response speed is extremely slow, for example, on the order of minutes. This is because it is not preferable for use.

  The ligands coordinated to the above transition metal complexes and rare earth metal complexes include acetylacetonato, 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 1,10 -Phenanthroline, 2-phenylpyridine, porphyrin, phthalocyanine, pyrimidine, quinoline and / or a derivative thereof can be exemplified, but is not limited thereto. One or more kinds of these ligands are coordinated with respect to one complex. In addition, a binuclear complex, a polynuclear complex, or a complex of two or more types of complexes can be used as the complex compound.

  In the light-emitting portion of the present invention, the metal atom serving as the central metal of the metal complex is constrained at one or more sites of the polymer. A method for achieving this is not particularly limited, and examples thereof include complexation by coordination bond as described above, complexation by charge transfer, ionic bond, and covalent bond. When the metal atom serving as the central metal is an ion, a method of neutralizing the light-emitting moiety is adopted for the above-described reason, and for example, it has a covalent bond sufficient to neutralize the valence of the ion together with the coordination bond. Although the method of using an organometallic compound is mentioned, it is not limited to this at all.

  The luminescent low molecular weight compound in the present invention is used by being dispersed in a polymer material. The polymer material may be an insulating polymer material or a charge transport polymer material in addition to the charge transport polyether, but is more preferably a charge transport polymer. When dispersed in an insulating material, a hole transporting host material such as a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, an aryl hydrazone derivative, or a porphyrin compound, or an oxadiazole derivative, a triazine derivative, or a triazole It is desirable to contain an electron transporting host material such as a derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyran dioxide oxide derivative, or a fluorenylidenemethane derivative. Here, examples of the insulating material include polystyrene, polyether, polyether, polymethyl methacrylate, and the like, but are not limited thereto. Examples of the charge transporting polymer include polyvinyl carbazole, polymethyl methacrylate having an aromatic amine in the side chain, polyether having an aromatic amine in the main chain, or polysilane, but is not limited thereto. .

Next, the layer structure of the organic EL device of the present invention will be described in detail.
The organic EL device of the present invention is composed of a pair of electrodes, at least one of which is transparent or translucent, and one or a plurality of organic compound layers including a light emitting layer sandwiched between the electrodes. At least one layer of the organic compound layer contains at least one kind of charge transporting polyether, and at least one layer of the organic compound layer contains a light-emitting low molecular weight compound.
In the organic EL device of the present invention, when there is one organic compound layer, the organic compound layer means a light emitting layer having a carrier transporting ability, and the light emitting layer includes the charge transporting polyether and the light emitting low molecular weight compound. It contains. When there are a plurality of organic compound layers (in the case of function separation type), at least one of them is a light emitting layer, and the other organic compound layers are carrier transport layers, that is, a hole transport layer, an electron transport layer, Or it means what consists of a positive hole transport layer and an electron carrying layer, and these at least one layer contains the said charge transportable polyether, and contains at least 1 sort (s) of the said luminescent low molecular weight compound in a light emitting layer.

  Specifically, for example, it is composed of at least a light emitting layer and an electron transport layer, at least composed of a hole transport layer, a light emitting layer and an electron transport layer, and composed of at least a hole transport layer and a light emitting layer. Or a light emitting layer having charge transporting capability, and at least one of these layers (hole transport layer or charge transport layer) contains the charge transporting polyester, and the light emitting layer further includes the light emitting property. Examples thereof include those containing at least one low molecular compound. In the organic EL device of the present invention, the light emitting layer may contain a charge transport material (a hole transport material other than the charge transport polyester, an electron transport material). Details will be described later.

Hereinafter, although it demonstrates in detail, referring drawings, it is not necessarily limited to these.
1 to 4 are schematic cross-sectional views for explaining the layer structure of the organic EL element of the present invention. In the case of FIGS. 1, 2, and 3, an example in which a plurality of organic compound layers are provided is shown. FIG. 4 shows an example in the case of one organic compound layer. 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 light emitting layer 6 having a carrier transport ability, an electron transport layer 5 and a back electrode 7 on a transparent insulator substrate 1. The organic EL element shown in FIG. 2 is formed by sequentially laminating a transparent electrode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5 and a back electrode 7 on a transparent insulator substrate 1. The organic EL element shown in FIG. 3 is formed by sequentially laminating a transparent electrode 2, a hole transport layer 3, a light emitting layer 6 having a carrier transport capability, and a back electrode 7 on a transparent insulator substrate 1. The organic EL element shown in FIG. 4 is formed by sequentially laminating a transparent electrode 2, a light emitting layer 6 having a carrier transport capability, and a back electrode 7 on a transparent insulator substrate 1. Each will be described in detail below.

  Depending on the structure of the organic compound layer containing the charge transporting polyether in the present invention, in the case of the layer structure of the organic EL device shown in FIG. 1, an electron transport layer 5 and a light emitting layer having carrier transport ability 6 can act as both the hole transport layer 3 and the electron transport layer 5 in the case of the layer structure of the organic EL device shown in FIG. In the case of the organic EL element layer configuration, both the hole transport layer 3 and the light emitting layer 6 having a carrier transport capability can act, and in the case of the organic EL element layer configuration shown in FIG. It can act as a light emitting layer 6 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, or the like is used. Further, the transparent electrode 2 is preferably transparent for extracting light emission and having a high work function for injecting holes, like the transparent insulator substrate. Indium tin oxide (ITO), tin oxide (NESA) ), An oxide film such as indium oxide and zinc oxide, and vapor deposited or sputtered gold, platinum, palladium, or the like is used.

  In the case of the layer structure of the organic EL element shown in FIGS. 1 and 2, the electron transport layer 5 may be formed of the charge transporting polyether provided with a function (electron transport ability) according to the purpose. Although it is good, it is formed by mixing and dispersing an electron transport material other than charge transporting polyether in the range of 1 to 50% by weight in order to adjust the electron mobility for the purpose of further improving the electrical characteristics. 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. Preferable specific examples include, but are not limited to, the following exemplary compounds (IV-1) to (IV-3). When the charge transporting polyether is not used, these electron transporting materials are formed alone.

  In the case of the layer structure of the organic EL device 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, aryl hydrazone derivatives, porphyrin compounds, and the like. (V-6) may be mentioned, but a tetraphenylenediamine derivative is preferred because of its good compatibility with the charge transporting polyether. Moreover, the mixture with other general purpose resin etc. may be sufficient. When the charge transporting polyether is not used, these hole transporting materials are formed alone.

  In the case of the layer structure of the organic EL device shown in FIG. 1, FIG. 2, or FIG. 3, the light emitting layer 4 is not formed of the light emitting low molecular weight compound alone, but improves the electric characteristics and the light emitting characteristics. For the purpose of the above, the light emitting low molecular weight compound is dispersed in the charge transporting polyether or dispersed in an insulating polymer material, and the charge transporting material is used as a host material in the range of 1 to 50% by weight. And may be formed by dispersing in a charge transporting polymer material other than the charge transporting polyether.

  In the case of the layer structure of the organic EL device shown in FIG. 3, the light-emitting layer 6 having a carrier transporting capability is the charge transporting polyether provided with a function (hole transporting capability or electron transporting capability) according to the purpose. The light-emitting material is an organic compound layer in which the light-emitting low-molecular compound is dispersed in an amount of 50% by weight or less. In order to adjust the balance between holes and electrons injected into the organic EL element, the charge-transporting poly You may disperse | distribute 10 to 50weight% of charge transport materials other than ether. 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 exemplified compounds (IV-1) to (IV-3). Moreover, it is preferable to use an organic compound that does not exhibit a strong electron interaction with the charge transporting polyether. More preferably, the following exemplified compound (VI) is used, but it is not limited thereto.

  Similarly, when adjusting the hole mobility, particularly preferable examples of the hole transporting material include tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, arylhydrazone derivatives, porphyrin compounds, and the like. Examples of the compounds (V-1) to (V-6) include tetraphenylenediamine derivatives because of their good compatibility with charge transporting polyethers.

In the case of the layer structure of the organic EL element shown in FIGS. 1 to 4, the back electrode 7 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. Further, a protective layer may be provided on the back electrode 7 in order to prevent the element from being deteriorated by moisture or oxygen. Specific protective layer materials include metals such as In, Sn, Pb, Au, Cu, Ag, and Al, MgO, SiO ₂ , TiO ₂ metal oxides, 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.

  In these organic EL devices shown in FIGS. 1 to 4, first, a hole transport layer 3 or a light emitting layer 6 having a carrier transport capability is formed on the transparent electrode 2 in accordance with the layer structure of each organic EL device. The hole transport layer 3 and the light emitting layer 6 having a carrier transport capability are prepared by dissolving or dispersing each of the above materials in an organic solvent, and using the obtained coating solution on the transparent electrode 2 by a spin coating method, a dip method, or the like. It forms by forming into a film using.

Next, depending on the layer structure of each organic EL element, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5 or the light emitting layer 6 having a carrier transporting capability is obtained by dissolving the above materials in an organic solvent. It is formed by dispersing and forming a film using the obtained coating solution on the transparent electrode using a spin coating method, a dip method or the like.
The thicknesses of the hole transport layer 3, the light emitting layer 4 and the electron transport layer 5 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 6 having carrier transporting ability 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 ball mill, a homogenizer, an ultrasonic method, or the like can be used.
Finally, the back electrode 7 is formed on the electron transport layer 5 or the light emitting layer 6 having carrier transport ability by a vacuum deposition method, thereby completing the device.
The organic EL element 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, for example, 4 to 20 V between a pair of electrodes.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Example 1)
1 part by weight of the above charge transporting polyether [Exemplary Compound (VII-1)] (Mw = 8.20 × 10 ⁴ ) as a charge transport material and 0.1 part by weight of the following Exemplified Compound (VIII) as a phosphorescent low molecular weight compound After mixing, a 10 wt% dichloroethane solution was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter. Using this solution, a light-emitting layer having a thickness of 0.15 μm and having a charge transport capability was formed on a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that had been washed and dried, by spin coating. . After sufficiently drying, the charge transporting polyether [Exemplary Compound (VII-3)] (Mw = 1.20 × 10 ⁵ ) as an electron transporting material was prepared as a 5 wt% dichloroethane solution, and then filtered with a 0.1 μm PTFE filter. After filtration, it was applied on the light emitting layer by a spin coating method to form an electron transport layer having a thickness of 0.1 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Example 2)
A charge transporting polyether [Exemplary Compound (VII-1)] (Mw = 8.20 × 10 ⁴ ) as a hole transporting material was prepared as a 5 wt% chlorobenzene solution, and a 0.1 μm polytetrafluoroethylene (PTFE) filter was prepared. Filtered through. Using this solution, a strip-type ITO electrode having a width of 2 mm, which had been washed and dried, was applied on a glass substrate formed by etching by spin coating to form a hole transport layer having a thickness of 0.1 μm. After sufficiently drying, 1 part by weight of the charge transporting polyether [Exemplary Compound (VII-2)] (Mw = 7.25 × 10 ⁴ ) as a charge transporting material and the Exemplified Compound as a phosphorescent low molecular compound ( VIII) is mixed with 0.1 part by weight to prepare a 10% by weight dichloroethane solution, filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and then applied onto the hole transport layer by a spin coat method to give a film thickness of 0.15 μm A light-emitting layer having the charge transporting ability was formed. Further, after sufficiently drying, a charge transporting polyether [Exemplary Compound (VII-3)] (Mw = 1.20 × 10 ⁵ ) as an electron transporting material was prepared as a 5 wt% dichloroethane solution and filtered with a 0.1 μm PTFE filter. After filtration, it was applied on the light emitting layer by a spin coating method to form an electron transport layer having a thickness of 0.1 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Example 3)
A charge transporting polyether [Exemplary Compound (VII-1)] (Mw = 8.20 × 10 ⁴ ) as a hole transporting material was prepared as a 5 wt% chlorobenzene solution, and a 0.1 μm polytetrafluoroethylene (PTFE) filter was prepared. Filtered through. Using this solution, a strip-type ITO electrode having a width of 2 mm, which had been washed and dried, was applied on a glass substrate formed by etching by spin coating to form a hole transport layer having a thickness of 0.1 μm. After sufficiently drying, 1 part by weight of the charge transporting polyether [Exemplary Compound (VII-2)] (Mw = 7.25 × 10 ⁴ ) as a charge transporting material and the Exemplified Compound as a phosphorescent low molecular compound ( VIII) is mixed with 0.1 part by weight to prepare a 10% by weight dichloroethane solution, filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and then applied onto the hole transport layer by a spin coat method to give a film thickness of 0.15 μm A light-emitting layer having the charge transporting ability 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Example 4)
As a charge transport material, 0.5 part by weight of the hole transporting polyether [Exemplary Compound (VII-1)] (Mw = 8.20 × 10 ⁴ ) and the charge transporting polyether [Exemplary Compound (VII-2)] (Mw = 7.25 × 10 ⁴ ) and 0.5 part by weight of the exemplified compound (VIII) as a phosphorescent low molecular weight compound to prepare a 10% by weight dichloroethane solution, and 0.1 μm polytetrafluoroethylene (PTFE) Filtered with a filter. Using this solution, a 2 mm wide strip-shaped ITO electrode that has been washed and dried is applied by spin coating on a glass substrate formed by etching to form a light-emitting layer having a charge transport ability of 0.15 μm in thickness. 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Comparative Example 1)
On a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that has been washed and dried, a thickness of 0.065 consisting of the following exemplary compound (IX) as a phosphorescent host material and the exemplary compound (VIII) as a phosphorescent material After forming a light emitting layer by co-evaporating a light emitting layer by co-evaporation so that (VIII) in (IX) is 5% by weight in the film, the electron transporting material is composed of the exemplified compound (VII). An electron transport layer having a thickness of 0.050 μm was formed by vacuum deposition. 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Comparative Example 2)
A hole transport layer having a thickness of 0.050 μm composed of the exemplified compound (V-2) as a hole transport material is vacuum-deposited on a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that has been dried after washing. It formed by the vapor deposition method. Further, a 0.065 μm thick light emitting layer composed of the exemplary compound (IX) as the phosphorescent host material and the exemplary compound (VIII) as the phosphorescent light emitting material is co-evaporated on the hole transport layer in a weight ratio in the film. After forming a light emitting layer by vapor deposition so that (VIII) in (IX) is 5%, an electron transport layer having a thickness of 0.050 μm composed of the exemplified compound (VI) as an electron transport material is formed by a vacuum deposition method. 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Comparative Example 3)
A hole transport layer having a thickness of 0.050 μm composed of the exemplified compound (V-2) as a hole transport material is vacuum-deposited on a glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that has been dried after washing. It formed by the vapor deposition method. Further, a 0.065 μm thick light emitting layer composed of the exemplary compound (IX) as the phosphorescent host material and the exemplary compound (VIII) as the phosphorescent light emitting material is co-evaporated on the hole transport layer in a weight ratio in the film. A light emitting layer was formed by vapor deposition so that (VIII) in (IX) was 5%. 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 intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Comparative Example 4)
From the above exemplified compound (IX) as the phosphorescent host material and the above exemplified compound (VIII) as the phosphorescent light emitting material on the hole transport layer on the glass substrate formed by etching a 2 mm wide strip-shaped ITO electrode that has been washed and dried. A luminescent layer with a thickness of 0.065μm is formed by co-evaporation to form a luminescent layer with a weight ratio of (IX) to (VIII) of 5% in the film, and then Mg-Ag alloy is co-evaporated. The back electrode having a width of 2 mm and a thickness of 0.15 μm was formed so as to intersect with the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

(Evaluation)
The organic EL device fabricated as described above is applied with a direct current voltage in vacuum (133.3 × 10 ^-3 Pa (10 ^-3 Torr)) with the ITO electrode side positive and the Mg-Ag back electrode negative. Measurement was performed to evaluate the maximum luminance and emission color at this time. The results are shown in Table 17. The emission lifetime of the organic EL device 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 (hour). The drive current density at this time is shown in Table 1 together with the element lifetime.

  As can be seen from Table 1, the organic EL device of the present invention has a very long device life despite its high luminance. Further, the drive current density is smaller than that of the conventional organic EL element. On the other hand, the conventional organic EL elements (Comparative Examples 1 to 4) are similar to the present invention in terms of luminance, but have a very short element life and a high driving current density.

It is typical sectional drawing which shows an example of the laminated constitution of the organic electroluminescent element of this invention. It is typical sectional drawing which shows another example of the layer structure of the organic electroluminescent element of this invention. It is typical sectional drawing which shows another example of the layer structure of the organic electroluminescent element of this invention. It is typical sectional drawing which shows another example of the layer structure of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent insulator board | substrate 2 Transparent electrode 3 Hole transport layer 4 Light emitting layer 5 Electron transport layer 6 Light emitting layer 7 with electric charge transport ability Back electrode

Claims (9)

In an electroluminescent device comprising one or more organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent, at least one of the organic compound layers is at least one of the following general formulas A charge transporting polyether represented by (II), and at least one of the organic compound layers is formed by passing an electronic energy level from an excited triplet state to a ground state or via an excited triplet state. An organic electroluminescent device comprising the following compound (VIII) that emits light upon transition to a ground state.

(In the general formula (II), the structure represented by the following general formula (II-1) represents a structure selected from the following formulas (VII-1) to (VII-3) , and R represents a hydrogen atom, Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and p represents an integer of 5 to 5,000.)


(In the formula (VII-1) to the formula (VII-3), n means p in the general formula (II).)   The organic compound layer is composed of at least a light emitting layer and an electron transport layer, and at least one of the light emitting layer and the electron transport layer contains at least one charge transporting polyether represented by the general formula (II), The organic electroluminescent element according to claim 1, wherein the light emitting layer contains the compound (VIII).   The organic electroluminescent element according to claim 2, wherein the light emitting layer contains a charge transporting material.   The organic compound layer is composed of at least a hole transport layer, a light emitting layer, and an electron transport layer, and at least one of or both of the hole transport layer and the electron transport layer is a charge transport property represented by the general formula (II). 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one polyether and the light emitting layer contains the compound (VIII).   The organic light emitting device according to claim 4, wherein the light emitting layer includes a charge transporting material.   The organic compound layer is composed of at least a hole transport layer and a light emitting layer, and at least one of the hole transport layer and the light emitting layer contains at least one charge transporting polyether represented by the general formula (II) And the said light emitting layer contains the said compound (VIII), The organic electroluminescent element of Claim 1 characterized by the above-mentioned.   The organic electroluminescent device according to claim 6, wherein the light emitting layer contains a charge transporting material.   The organic compound layer is composed of only one light emitting layer having charge transporting ability, and the light emitting layer includes at least one charge transporting polyether represented by the general formula (II), the compound (VIII), and The organic electroluminescent element according to claim 1, comprising:   The organic electroluminescent device according to claim 8, wherein the light emitting layer contains a charge transporting material.