JP2002324681A - Light emitting element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film EL element, and its manufacturing method, which can be manufactured in a simple process of mixing heavy metal in an organic light emitting layer as against a heavy metal complex doping element, has a high luminous efficiency, is of small concentration quenching and can be used stably for a long period of time. SOLUTION: A hole transport layer 3 is formed on a substrate 1 with a hole injection electrode 2, and then, [4-(2,2-diphenylvinyl) phenyl][4-(diphenylamino)phenyl]phenylamine and Ir are formed into a film thickness of about 40 nm at deposition speeds of 0.3 nm/sec, 0.01 nm/sec each as a hole transport light emitting layer of a light emitting region 4, and Ir almost in a state of a single atom is dispersed/mixed in the light emitting region. Next, an electron transport layer 5 is formed in film thickness of about 20 nm, and an negative electrode 6 is formed in film thickness of about 100 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film electroluminescence (EL) element, for example, a self-luminous light-emitting element that can be used as a light source for various purposes such as a flat-type self-luminous display device, communication, lighting, and the like. The present invention relates to a method and a display device using the same.

[0002]

2. Description of the Related Art In recent years, LCD panels (liquid crystal display panels) have been widely used as flat display devices, but they still have disadvantages such as a slow response speed and a narrow viewing angle. However, the new method has problems such as insufficient characteristics and an increase in panel cost. Under such circumstances, thin-film EL devices as new light-emitting devices, which are self-luminous, have excellent visibility, have high response speed, and can be expected to be used in a wide range of applications, are attracting attention. In particular, thin-film EL devices that use organic materials that can use simple film-forming processes such as evaporation and coating at room temperature for all or some of the layers of the device are also called organic EL devices. Many studies have been conducted with the attraction that the cost can be relatively low.

[0003] A thin film EL element (organic electroluminescence element, hereinafter abbreviated as "organic EL element") operated by a DC electric field exists between a pair of electrodes composed of a hole injection electrode and a cathode (electron injection electrode). In the light emitting region, electrons and holes are injected from the electrode to obtain light emission by recombination, and many studies have been made for a long time. It was far from applied.

Under such circumstances, a device proposed by Tang et al. In 1987 (CW Tang and
S. A. Vanslyke: Appl. Phys. Le
tt. 51 (1987) 913. September 21, 1987
Issued on a transparent substrate, a hole injection electrode, a hole transport layer,
An element having a light-emitting layer and a cathode in this order, in which ITO (indium-tin oxide) is used as a hole injection electrode, a 75-nm-thick diamine derivative layer is used as a hole-transport layer, and 60-nm-thick aluminum is used as a light-emitting layer. Quinoline complex layer,
As the cathode, an MgAg alloy having both electron injection properties and stability against alteration was used. In particular, while improving the cathode, by using a diamine derivative having excellent transparency as the hole transport layer, sufficient transparency can be maintained even at a film thickness of 75 nm. Since a uniform thin film free of a pinhole or the like can be obtained sufficiently, the total film thickness of the element including the light emitting layer can be made sufficiently thin (about 150 nm), and high-luminance light can be emitted at a relatively low voltage. Can now be obtained. Specifically, a high luminance of 1000 cd / m ² or more and a high efficiency of 1.5 lm / W or more are realized at a low voltage of 10 V or less. The report of Tang et al. Has led to active studies to date, such as further improvement of the cathode, device construction such as insertion of an electron injection layer and insertion of a hole injection layer, and the like. .

[0005] The thin film EL generally studied at present is described below.
The (organic EL) element will be outlined.

Each layer of the device is formed by laminating a hole injecting electrode, a hole transporting layer, a light emitting layer, and a cathode on a transparent substrate in this order. A hole injection layer may be provided, an electron transport layer may be provided between the light emitting layer and the cathode, and an electron injection layer may be provided at the interface with the cathode. In this way, by making each layer play a role by separating the function, an appropriate material can be selected for each layer, and the characteristics of the element are also improved.

As a transparent substrate, generally, "Corning 17"
A glass substrate such as 37 "(alkali-free borosilicate glass manufactured by Corning Glass Works) is widely used. A plate thickness of about 0.7 mm is easy to handle from the viewpoint of strength and weight.

As the hole injection electrode, a transparent electrode such as an ITO sputtered film, an electron beam evaporated film, or an ion plating film is used. The film thickness is determined from the required sheet resistance value and the visible light transmittance. However, since the driving current density is relatively high in the organic EL device, the organic EL device may be used at a thickness of 100 nm or more to reduce the sheet resistance. Many.

The hole transport layer is made of N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine (hereinafter referred to as T
PD), N, N'-bis (α-naphthyl)-
Diamine derivatives used by Tang et al., Such as N, N'-diphenylbenzidine (hereinafter referred to as NPD), particularly U.S. Pat. No. 4,539,507 (issued on Sep. 3, 1985) [Corresponding Japanese Patent No. 2037475 No. (Japanese Unexamined Patent Publication No. 59-194399: Published date: November 5, 1984)
The vacuum-deposited film of a diamine derivative having a Q ¹ -GQ ² structure disclosed in JP-A-2001-260926 is widely used. Here, Q ¹ and Q ² are independently a group having a nitrogen atom and at least three carbon chains (at least one of which is aromatic), and G is a cycloalkylene group, an arylene group, an alkylene group, -A linking group comprising a carbon bond. These materials are generally excellent in transparency, are almost transparent even at a film thickness of about 80 nm, and are excellent in film formability, so that films without defects such as pinholes can be obtained.
Even if the thickness is reduced to about m, there is a feature that a reliability problem such as a short circuit hardly occurs.

As in the case of the report by Tang et al., The light-emitting layer is generally formed by using an electron-transporting light-emitting material such as tris (8-quinolinolato) aluminum in a thickness of several tens nm by vacuum deposition. The light emitting layer is made relatively thin and the electron transporting layer is made of
A so-called double hetero structure in which m layers are stacked may be employed.

The cathode is made of an alloy of a metal having a low work function and a low electron injection barrier, such as an MgAg alloy or an AlLi alloy proposed by Tang et al., And a metal having a relatively large work function and being stable, or various electron injection layers such as LiF. A laminated cathode with aluminum or the like is often used.

In addition to the layered structure of the hole transporting layer / electron transporting light emitting layer, the configuration of the hole transporting light emitting layer / electron transporting layer and the structure of the hole transporting layer / light emitting layer / electron transporting layer are different. Configurations are also widely used. In any case of using any of the layer configurations, the transparent substrate, the hole injection electrode, and the cathode are similarly used as described above.

In general, it is difficult to obtain a compound having an excellent electron-transfer ability with an organic compound, and a relatively limited number of compounds can be used in a laminated structure of a hole-transporting layer / an electron-transporting light-emitting layer. In the structure of the hole transporting light emitting layer / electron transporting layer and the hole transporting layer / light emitting layer / electron transporting layer, many kinds of materials can be used for the light emitting layer, and various luminescent colors can be obtained, and the efficiency and the lifetime can be obtained. Also, there is a possibility that a high-performance one can be obtained, and it is expected.

For example, US Pat. No. 5,085,947 (issued on Feb. 4, 1992)
No. 0292, published on Oct. 8, 1990]
An element having a structure of a hole transporting light emitting layer / an electron transporting layer, and [4- {2- (naphthalen-1-yl) vinyl} phenyl] bis (4-methoxyphenyl) as a hole transporting light emitting material.
An element using an amine or [4- (2,2-diphenylvinyl) phenyl] bis (4-methoxyphenyl) amine and using an oxadiazole derivative in an electron transport layer is disclosed.

[0015] Further, International Patent Publication WO96 / 2227.
No. 3 (International publication date: July 25, 1996) discloses an element having a structure of a hole transporting layer / a light emitting layer / an electron transporting layer. An organic thin-film EL device using (2,2-diphenyl-1-vinyl) -1,1′-biphenyl is disclosed.

In 1998, MRS (Material Researc)
h Society) Spring Annual Session G2.1 Lecture (199
(Announced on April 13, 4), a proposal by Tang et al. For a hole-transporting luminescent material in a device having a hole-injecting layer / a hole-transporting luminescent layer / a hole-blocking layer / an electron-transporting layer. Done Q
Devices using NPD is ¹ -G-Q ² type compounds are disclosed.

As described above, by using not only the electron-transporting light-emitting material but also the hole-transporting light-emitting material, it is possible to design a wide range of materials and obtain various emission colors. At present, it is not possible to obtain a material having sufficient characteristics in terms of efficiency and life. In particular, when a fluorescent material is used, it is said that only 25% of the excited state formed by the recombination of electrons and holes contributes to light emission, which is a major obstacle when aiming for further improvement in efficiency. I was

Under such circumstances, more recently, Appl.
Phys. Lett. , Vol. 75, no. 1, p.
4-6. (Issued on July 5, 1999), devices using a light-emitting layer in which a heavy metal complex is doped into a host material have been actively studied. In these devices, it is said that triplet excitons that do not contribute to light emission, which are originally said to be forbidden transitions, can undergo light emission transition to the ground state by the heavy metal effect, and are generated at a rate of 75%. It is said that a triplet exciton that can be used for light emission can achieve high efficiency.

[0019]

SUMMARY OF THE INVENTION However, fac tris (2-phenylpyridine) iridiu disclosed in the above-mentioned article is disclosed.
m] [abbreviation: Ir (ppy) 3], and many heavy metal complexes are not always easy to synthesize and purify. In addition, a layer composed of a single material does not have sufficient charge transporting ability, and concentration quenching (not less than a certain concentration) Light emission intensity is reduced), so that heavy metal complexes are usually doped at an appropriate concentration in a host material having a charge transporting property. However, efficiency and lifetime depend on the doping concentration. There were manufacturing disadvantages.

In view of such circumstances, the present inventors have designed heavy metal complex materials having various structures, and have not only thoroughly investigated the properties thereof, but also deposited heavy metals and various compounds independently as a mixture. As a result of conducting extensive research on the light emitting element included in the light emitting layer by making the light emitting layer, the heavy metal and the compound contributing to light emission do not necessarily have to be a single compound as a complex. Even when heavy metals are physically mixed and present in close proximity to each other, it has been found that a phenomenon in which the luminous efficiency is greatly improved is widely observed as compared with the case where no heavy metals are contained, and the present invention has been found. It was completed. Furthermore,
The inventors have found that when the mixed heavy metals are mixed in a state as fine as possible, the luminous efficiency is further improved, thereby completing the present invention.

That is, the present invention can be manufactured by a simple process of mixing a heavy metal into an organic light emitting layer, has a high luminous efficiency, is free from defects such as unevenness and black spots, as compared with a conventional heavy metal complex doped device. Provided is a thin-film EL device which emits light with excellent visibility by self-emission at a low driving voltage, has a small decrease in luminance even in a continuous light emission test, consumes little power, and can be used stably for an extremely long period of time, and a method of manufacturing the same. The purpose is to do.

[0022]

In order to achieve the above object, a light emitting device of the present invention, a method of manufacturing the same, and a display device using the same are as follows.

(1) A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region contains a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal as a mixture.

(2) A light emitting element having at least a light emitting region between a pair of electrodes, wherein the light emitting region is obtained by simultaneously depositing a light emitting material, a compound capable of sustaining charge transport, and a heavy metal. A light-emitting element comprising a mixture of materials.

(3) The light emitting device according to the above (1) or (2), wherein the content ratio of the heavy metal in the light emitting region is from 0.1 mol% to 50 mol% based on the light emitting material.

(4) The mixed heavy metal is composed of a heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average of 10 or less atoms of the heavy metal. A light emitting device according to any one of the above 3).

(5) The mixed heavy metal is composed of a heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. A light emitting device according to any one of the above 3).

(6) A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport in the compound and a light-emitting region. A light-emitting element containing, as a mixture, a compound having a contributing portion and a heavy metal.

(7) A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport in the compound and a light-emitting region. A light-emitting element including a mixture of materials obtained by simultaneously depositing a compound having a contributing portion and a heavy metal.

(8) The compound (6) or (7), wherein the compound capable of sustaining charge transport comprises a hole-transporting luminescent material having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound. The light-emitting element according to item.

(9) The content ratio of heavy metal in the light emitting region is 0 with respect to a compound capable of sustaining charge transport and having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound. .1mol% -50m
The light emitting device according to any one of the above items (6) to (8), which is ol%.

(10) The mixed heavy metal is composed of the heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 10 or less. A light-emitting device according to any one of the above items 9).

(11) The mixed heavy metal is composed of heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. A light-emitting device according to any one of the above items 9).

(12) A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region contains a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal as a mixture. A light-emitting element in which the ratio of light emission to recombination of unit charges is increased as compared with the case where a region is formed only of a mixture of a light-emitting material and a compound capable of sustaining charge transport.

(13) A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport in the compound and a light-emitting region. A compound having both a contributing portion and a heavy metal, and containing the mixture as a mixture, the light emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport and a portion contributing to light emission in the compound. A light-emitting element in which the ratio of light emission to recombination of unit charges is increased as compared to the case where the light-emitting element is made of only a compound having

(14) The mixed heavy metal described in the above item (12) or (12), wherein the mixed heavy metal is an ultrafine particle-shaped heavy metal selected from atomic particles of the heavy metal and cluster particles having an average of 10 or less atoms of the heavy metal. (13) The light-emitting device according to item (13).

(15) The mixed heavy metal described in the above item (12) or (12), wherein the mixed heavy metal is a heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average of 5 or less atoms of the heavy metal. (13) The light-emitting device according to item (13).

(16) The light emitting device according to any one of the above (1) to (15), wherein the heavy metal is mainly a metal having an atomic number of 57 or more.

(17) A method for manufacturing a light emitting device having at least a light emitting region between a pair of electrodes, wherein at least one layer in the light emitting region comprises a light emitting material, a compound capable of sustaining charge transport, and a heavy metal. For manufacturing a light-emitting element in which a film is formed by simultaneously depositing a light-emitting element.

(18) The method for manufacturing a light-emitting device according to the above (17), wherein the deposition of the heavy metal is deposition deposited through cracking means.

(19) A method for manufacturing a light-emitting element having at least a light-emitting region between a pair of electrodes, wherein at least one layer in the light-emitting region is a compound capable of sustaining charge transport and mainly containing the compound in the compound. A method for manufacturing a light-emitting element in which a compound having both a portion contributing to charge transport and a portion contributing to light emission and a heavy metal are simultaneously deposited to form a film.

(20) The method for manufacturing a light-emitting device according to the above item (19), wherein the deposition of the heavy metal is deposition through cracking means.

(21) The method for manufacturing a light emitting device according to any one of the above (17) to (20), wherein the heavy metal is mainly a metal having an atomic number of 57 or more.

(22) A display device using a plurality of light emitting elements having at least a light emitting region between a pair of electrodes, wherein the light emitting region in the light emitting element comprises a light emitting material, a compound capable of sustaining charge transport, and a heavy metal. And a light-emitting region containing the mixture as a mixture.

(23) A display device using a plurality of light-emitting elements having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region in the light-emitting element is a compound capable of sustaining charge transport, and A display device comprising a light-emitting region containing, as a mixture, a compound having both a portion mainly contributing to charge transport and a portion contributing to light emission, and a heavy metal.

(24) The mixed heavy metal described in the above (22) or (22), wherein the heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 10 or less. 23. The display device according to item 23).

(25) The mixed heavy metal described in (22) or (22) or (7), wherein the mixed heavy metal is an ultrafine particle-shaped heavy metal selected from atomic particles of the heavy metal and cluster particles having an average of 5 or less atoms of the heavy metal. 23. The display device according to item 23).

(26) The display device according to any one of (22) to (25), wherein the heavy metal is mainly a metal having an atomic number of 57 or more.

(27) A light emitting device in which a heavy metal is contained as a mixture in an organic light emitting layer.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thin film EL device (organic EL device) according to an embodiment of the present invention will be described.

The light emitting device of the present invention has a light emitting region disposed between at least a pair of electrodes. Here, a light-emitting element having “a light-emitting region disposed between at least a pair of electrodes” includes at least a hole-injection electrode, an electron-injection electrode provided to face the hole-injection electrode, and both directly or It consists of at least a pair of electrodes, such as a light emitting functional layer sandwiched indirectly, and a light emitting functional layer arranged somewhere between them. Here, the light emitting functional layer means not only a light emitting layer that actually emits light, but also (1) a hole transporting layer / electron transporting light emitting layer, (2) a hole transporting light emitting layer / electron transporting layer, and (3) Various configurations such as a hole transporting layer / a light emitting layer / an electron transporting layer (however, the light emitting layer includes an electron transporting light emitting layer, a hole transporting light emitting layer, and the like).

The “light emitting region” in the present invention means a layer that actually emits light among the light emitting functional layers as described above. That is, (1) is an electron transporting light emitting layer, (2) is a hole transporting light emitting layer, and (3) is a portion corresponding to the light emitting layer.

A feature of the present invention is that a heavy metal is present as a mixture in the material constituting the light emitting region of the organic EL device. The light-emitting region includes the light-emitting layer of a so-called organic EL element as described above.

The light emitting region used in the present invention includes, for example, the following types (A) and (B) when classified in more detail.

(A): a luminescent region containing a luminescent material (a), a compound (b1) capable of sustaining charge transport and a heavy metal (c) as a mixture; (B): a compound capable of sustaining charge transport The light-emitting region includes a compound (b2) having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound and a heavy metal (c) as a mixture.

The compound (b2) which can maintain charge transport and has both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound has a small charge transporting function. May further use, if necessary, a compound (b1) capable of sustaining charge transport,
The light emitting region containing the compound (b2), the compound (b1), and the heavy metal (c) as a mixture can also be used.

Of the above, it is particularly preferable to use the (B) type light emitting region from the viewpoint that a large area light emitting region can be uniformly formed with a high yield and a stable film can be formed.

The compound (b1) in the light emitting region of the type (A) is a guest material because, as a technical common sense of an organic thin film EL element, light emission does not occur only with the compound (b1) that can sustain charge transport. The compound (b1), which is a host material and can sustain the charge transport, is used as a dopant by using the light emitting material (a) as a dopant.

As the light emitting material (a), an ordinary organic EL
A laser dye material used as a light-emitting dye or the like may be used for the light-emitting layer of the element.

On the other hand, the compound (b2) which is a compound capable of sustaining charge transport used in the light emitting region of the type (B) and having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound (b2) ) Is a compound having a portion contributing to light emission and capable of sustaining charge transport, so that it is not particularly necessary to use the luminescent material (a) in combination.

In each of the above types (A) and (B),
The light-emitting region is preferably formed by depositing the respective materials constituting the light-emitting region at the same time to form a film, thereby forming a mixture of the respective materials. The deposition method includes vacuum deposition and electron beam (EB) deposition. , Sputtering, ion plating and the like can be applied.
When such components are deposited, it is preferable to deposit the heavy metal through cracking means in order to disperse and mix the heavy metal as fine particles as possible, more preferably, as atomic heavy metal particles in the light emitting region. The finer the heavy metal particles, the higher the luminous efficiency of the light emitting element, which is preferable.

As described above, each layer of the light emitting device of the present invention comprises a hole injection electrode, a hole transport layer, a light emitting layer,
A cathode is formed by laminating in this order, a hole injection layer is provided between the hole injection electrode and the hole transport layer as necessary, an electron transport layer is provided between the light emitting layer and the cathode, and an electron injection is performed at the interface with the cathode. Layers can be provided. In addition, as described above, a combination of layers having the above functions sandwiched between electrodes is referred to as a light emitting functional layer in the present invention, and a layer that actually emits light among the light emitting functional layers is referred to as a light emitting region. Is called. Conventionally,
Usually, a layer called “light-emitting layer” is included in the light-emitting region according to the present invention.

As described above, in the present invention, an appropriate transparent or opaque substrate is used in the same manner as a normal light emitting element, and a method of forming the above element structure on the substrate can be used. In order to extract light emission outside the device, a transparent or at least translucent electrode is usually used on at least one side of the pair of electrodes. When the surface on which the substrate exists is a transparent or translucent electrode, the substrate is usually a transparent or translucent substrate. When an opaque substrate is used, a transparent or translucent electrode is used as an electrode provided on the side opposite to the surface where the substrate exists.

The substrate may be any as long as it can carry the light emitting device of the present invention.
Thin film E such as alkali-free borosilicate glass manufactured by ass Works
A glass substrate usually used for an L element is often used, but polyester and other resin films can also be used.

The thickness of the substrate is not particularly limited.
The range is preferably about 3 mm to 1.1 mm, and in the case of a resin film substrate, the range is preferably about 50 μm to 1 mm.

The hole injecting electrode in the present invention may be any as long as it can function as an anode and inject holes into the device. In many cases, the hole injecting electrode is a transparent electrode. In such a case, an ITO (indium tin oxide) film is generally used in many cases, and the ITO film is formed by a film forming method such as sputtering, electron beam evaporation, or ion plating for the purpose of improving its transparency or reducing its resistivity. Various post-treatments are often performed for the purpose of controlling resistivity and shape. The film thickness is determined from the required sheet resistance value and visible light transmittance. However, since the driving current density is relatively high in the organic EL element,
It is often used with a thickness of 100 nm or more to reduce sheet resistance. These normal ITO films can be used for the hole injection electrode of the present invention.
“IDIXO” [a transparent electrode material manufactured by Idemitsu Kosan Co., Ltd., composed of a hexagonal layered compound composed of indium / zinc oxide and indium oxide. Molecular formula (general formula) In ₂ O ₃ (ZnO)
_n (where n is an integer of 3 or more; the upper limit of n is not particularly limited, but is generally 100 or less, preferably 10 or less)
Indicated by ] And various improved transparent conductive layers can also be widely used. Further, a coating film of a transparent conductive paint in which a conductive powder is dispersed and other electrodes can be used.

The light-emitting region in the present invention may be any as long as it emits light in an environment coexisting with heavy metals. The characteristics of the compound itself include various hole-transporting light-emitting materials and electron-transporting light-emitting materials, as well as conventional compounds. Various materials can be used widely, including the compounds used in the light emitting layer of the organic EL element, and a compound capable of sustaining charge transport and a portion contributing to charge transport within the single compound and emitting light. Particularly, a material which has a portion contributing to the light emission and functions well as a light emitting layer even if it is a layer made of a single material is particularly preferably used. These materials form a single layer as a light-emitting region (light-emitting layer), and preferably form a light-emitting functional layer in combination with a hole transport layer and an electron transport layer. On the other hand, the coexistence with heavy metals significantly improves luminous efficiency. The tendency is noticeable.

In particular, since its molecular structure has a tetraphenylenediamine skeleton, it has higher EL luminous efficiency and longer lifetime than triphenylamine dimer (TPD or the like) generally called Q ¹ -GQ ² structure. And the asymmetric molecular structure makes it possible to realize a long-life element that is hardly associated with each other, hardly causes crystallization or aggregation, and has extremely excellent durability. More specifically, a phenyl group directly bonded to one nitrogen of tetraphenylenediamine serving as a skeleton is substituted with a bulky group such as phenylstyryl, diphenylbutadienyl, anthryl, and a phenyl group directly bonded to the other nitrogen. When the group is unsubstituted or alkyl- or alkoxy-substituted, the intermolecular interaction between the moieties is increased as compared with the other, and the hole transport ability is improved. In addition, the use of such a compound not only improves the lifetime but also significantly improves the luminous efficiency when used as a non-doped light-emitting layer containing only such molecules. This is thought to be due to the strong concentration quenching due to the interaction between the moieties contributing to the luminescence transition in the molecule in the case of a molecule that easily associates, but it has been revealed as a remarkable fact in the present invention. Such a group of compounds further improves the luminous efficiency remarkably by coexistence of heavy metals.

Particularly, in a compound having a portion whose molecular structure contributes to luminescence transition and a portion which contributes to hole transport, sufficient charge transport and luminescence can be simultaneously sustained, and a remarkable effect is recognized. .

Specific examples of the above compound, that is, the compound (b2) used in the above-mentioned (B) type light emitting region include, for example, [4- (2,2-diphenylvinyl) phenyl] [4- (Diphenylamino) phenyl] phenylamine (abbreviation “PPDA-PS”), 4-
(2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine (abbreviation "M2PPDA-P
S ″), (4-{[4- (2,2-diphenylvinyl)
Phenyl] (4- (9-anthryl) phenyl) aminodiphenyl) diphenylamine (abbreviation “PPDA-P
SA ″), and (4-{[4- (2,2-diphenylvinyl) phenyl] [4- (10-methoxy (9-anthryl)) phenyl] amino} phenyl) diphenylamine (abbreviation “PPDA-PS -AM ").

When a compound (b2) capable of sustaining charge transport and having a portion mainly contributing to charge transport and a portion contributing to light emission is used in the compound, the heavy metal in the light emitting region is used. The content ratio of (c) is 0.1 mol% to 50 m with respect to compound (b2).
ol% is preferable, and more preferably 0.5 mol% to 2 mol%.
The range is 0 mol%. When the light-emitting region is formed without using the above-described “compound having both a portion contributing to charge transport and a portion contributing to light emission in one compound”, a general-purpose charge transport material is used as a host material. Used as
A configuration in which a general-purpose luminescent dye is doped by co-evaporation and heavy metals coexist as a mixed layer can be used. The above-described (A): a light-emitting region containing a mixture of the light-emitting material (a), the compound (b1) capable of sustaining charge transport, and the heavy metal (c) corresponds to this. Here, as a general-purpose charge transporting material, that is, as a material corresponding to the compound (b1), various hole transporting materials such as the above-mentioned triphenylamine-based hole transporting materials such as TPD and NPD, stilbene-based and hydrazone-based materials can be used. In addition to materials, various metal complexes such as aluminum quinolinol complexes and various electron transport materials such as oxadiazole derivatives and triazole derivatives can also be used. In addition, 4,4′-bis (carbazol-9yl) biphenyl (abbreviation: CBP) is also preferably used. Further, as the light emitting material (a),
Various general-purpose light-emitting dyes can be used, for example, various light-emitting dyes such as coumarin derivatives, quinacridone derivatives, phenoxazone derivatives, etc. Can be used widely.

The ratio of the light emitting material (a) and the compound (b1) capable of sustaining charge transport is preferably (a) 1
0.1 to 1000 mol of (b1) to mol, more preferably (b1) 1 to 1 mol of (a)
５００500 mol.

In the light emitting region of the type (A),
The content ratio of the heavy metal (c) is set to 0.
It is preferably in the range of 1 mol% to 50 mol%, more preferably in the range of 0.5 mol% to 20 mol%.

The heavy metal in the present invention may be any heavy metal that contributes to an increase in the probability of a triplet exciton, which is originally a forbidden transition, to the luminescence transition to the ground state by the so-called heavy metal effect. For example, a remarkable effect was observed when the atomic number was 57 or more. In particular, the upper limit of the atomic number of the heavy metal is not particularly limited, but usually, the atomic number is 8
5 or less are easy to handle. Above all, Ir, Au, Pt
Is preferred.

As described above, in order to form the light emitting region of the present invention, it is preferable that the respective materials constituting the light emitting region are simultaneously deposited by co-evaporation or the like to form a mixture of the respective materials. For example, a method such as vacuum deposition, electron beam (EB) deposition, sputtering, or ion plating can be applied. When such components are deposited, it is preferable to deposit the heavy metal through cracking means in order to disperse and mix the heavy metal as fine particles as possible, more preferably, as atomic heavy metal particles in the light emitting region.

When a heavy metal is deposited by the above-described vacuum deposition or other deposition method, if a plurality of atoms of the metal are present in a light-emitting region in a so-called large cluster state in which a plurality of atoms of the metal are grouped, it is sufficient to improve the light emission efficiency. Since it does not contribute, high luminous efficiency can be achieved by using the heavy metal as small as possible in atomic cracking. Ideally, it is considered preferable to co-evaporate all of them in an atomic state. For this reason, it is preferable to deposit through a cracking means, such as using an ion plating apparatus in which a plasma cracker is combined with a normal EB vapor deposition apparatus. In the light-emitting device of the present invention, in order to obtain a preferable result, the average number of heavy metal atoms contained in the cluster is 5 or less, preferably 3 or less, more preferably 1.5 or less. It is preferable to reduce the size of heavy metal particles, such as clusters of not more than one, as much as possible from the viewpoint of improving luminous efficiency.

As the other layers in the device, general hole injection layers, hole transport layers, and electron transport layers can be widely used. The hole injecting layer is made of starburst amine (starburst amine) for the purpose of smoothing the surface roughness of ITO, improving the hole injecting efficiency, lowering the driving voltage, and extending the service life.
amine) derivatives, oligoamine derivatives, and the like are often used, and are sometimes referred to as buffer layers. As the hole transporting layer, in addition to the above-described TPD and NPD, a hole transporting material having a relatively small molecular weight and a three-dimensionality is used for a hole transporting material having a relatively large molecular weight and a poor stericity and easily associated as it is. It can also be used in combination with a technique for realizing excellent characteristics by blending.

Here, “a hole transporting material having a relatively large molecular weight and a poor stericity and easily associated as it is” includes N, N′-bis (4′-diphenylamino-4
Triphenylamine multimers such as -biphenylyl) -N, N'-diphenylbenzidine (abbreviation: TPT), "a hole transport material having a relatively small molecular weight and steric properties"
Examples thereof include stilbene compounds such as 4-N, N-diphenylamino-α-phenylstilbene (abbreviation: PS). In addition, various materials conventionally used for organic thin film EL elements can also be used as the blended hole transport layer.

As the electron transporting layer, not only metal complex systems widely studied since Tang et al. Used tris (8-quinolinolato) aluminum, but also oxadiazole derivatives, triazole derivatives and other materials can be widely used. .

The electron injection electrode according to the present invention is, as described in the prior art, a metal having a low work function and a low electron injection barrier, such as a MgAg alloy or an AlLi alloy proposed by Tang et al. In addition to using an alloy with a metal, a laminated cathode of Li and Al, L
Various generally reported cathodes such as a stacked cathode of iF and Al can be used.

The light emitting device of the present invention can be applied to an information display device such as a character type, a symbol, an image, etc. using a plurality of light emitting devices instead of an LCD panel, for example, a flat type self light emitting display device. In these display devices, several or several tens of single-color light-emitting elements are arranged in a matrix to display one character, and a total of hundreds of light-emitting elements in the vertical and horizontal directions, that is, tens of thousands to hundreds of thousands of light-emitting elements in total. Examples include a device for displaying characters and symbols in which elements are arranged, or a color display device in which RGB three-color (red, green, and blue) light-emitting elements are used as a set of pixels and pixels are arranged vertically and horizontally in a matrix. Is done.

The light emitting device of the present invention (1), (6),
In the inventions described in (12) and (13), the main part is a compound in which a light-emitting region can sustain charge transport in a light-emitting element having a light-emitting region arranged between at least a pair of electrodes. : A combination of (a) and (b1) in the (A) type, and (b2) in the (B) type are collectively expressed here as a compound capable of sustaining charge transport), and a heavy metal Is contained as a mixture. By containing a compound capable of transporting charges in the single layer in the light emitting region, charge transport is continuously maintained, and recombination of electron holes in the light emitting region and its periphery or interface is maintained. By containing a heavy metal together with the compound, a light emission transition from a triplet excited state, which is originally non-emissive due to forbidden transition, to a ground state, becomes possible by a so-called heavy metal effect, and a naturally high non-emissive state generated at a considerably high rate Certain triplet excitons can be used for light emission, and extremely high luminous efficiency can be obtained.

In the invention described in the above items (2) and (7) of the light emitting device of the present invention,
The compound in which the compound capable of transporting charges in a single layer is formed in the light emitting region by simultaneously depositing a compound capable of sustaining charge transport and each component material constituting the light emitting region such as heavy metal to form a mixture of the materials. , The charge transport is continuously maintained, and the recombination of electron holes at the light emitting region and its periphery or interface is maintained. Then, the heavy metal is simultaneously deposited with the compound to form a mixed layer of the material, so that the emission transition from the triplet excited state, which is originally a non-emission due to forbidden transition to the ground state, is enabled by the so-called heavy metal effect. Triplet excitons that are originally non-emitting and are generated at a high rate can be used for light emission, and extremely high luminous efficiency can be obtained.

In particular, in the light emitting device of the present invention, as described in the above items (6) and (7), the compound capable of sustaining charge transport includes, in the compound, a portion mainly contributing to charge transport and a component contributing to light emission. When the compound (b2) having both a moiety and a compound is used, sufficient charge transport and light emission can be simultaneously maintained, and further remarkable high light emission efficiency is recognized, which is preferable.

In the light emitting device of the present invention, as described in the above item (8), the compound capable of sustaining charge transport in the above item (6) or (7) is a hole transporting light emitting material. As a result, sufficient charge transport and light emission can be simultaneously maintained, and further remarkable high light emission efficiency is recognized, which is preferable.

In the light emitting device of the present invention, as described in the above (3) and (9),
In the above (3), the content ratio of the heavy metal is 0.1 mol% to 50 mol% with respect to the luminescent material, and the content ratio of the above (9)
In the section, 0.1 mol of a compound capable of sustaining charge transport and having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound.
When the content is in the range of 50 to 50 mol%, sufficient charge transport and light emission can be simultaneously sustained, and further remarkable high light emission efficiency is recognized, which is preferable.

In the invention described in the above (16), (21) and (26), the main part is that the heavy metal is
It is mainly a metal having an atomic number of 57 or more. This makes it possible to use a material other than a luminescent material, such as a compound capable of sustaining charge transport and a compound having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound, in which fluorescence or phosphorescence is generally strongly recognized. Also, a wide range of organic compounds are preferred, and high luminous efficiency can be obtained by coexistence with these heavy metals having an atomic number of 57 or more.

The above (4), (5), (10), (1)
In the inventions described in 1), (14), (15), (24) and (25), the heavy metal mixed with the heavy metal has an average number of atomic particles of the heavy metal and the number of atoms of the heavy metal. An ultrafine particulate heavy metal selected from 10 or less cluster particles, preferably an atomic fine particle of the heavy metal and an ultrafine particulate heavy metal selected from cluster particles having an average number of 5 or less atoms of the heavy metal. As described above, it is preferable that the heavy metal particles be present in the light emitting region in a state as small as possible, because the light emitting efficiency is improved.

Next, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these specific examples. In addition, each luminescent material is
In particular, compounds other than those for which the sources were obtained were synthesized by a conventional method as shown in the exemplified synthesis examples and used after sufficient purification.

(Example 1) FIG. 1 is a schematic sectional view of an organic thin-film electroluminescence element which is a light-emitting element of the present invention. In FIG. 1, 1 is a transparent substrate, 2 is a hole injection electrode, 3 is a hole transport layer, 4 is a light emitting region according to the present invention, and contains a compound capable of sustaining charge transport and a heavy metal. Represents a hole transporting light emitting layer, 5 represents an electron transporting layer, and 6 represents a cathode. The light-emitting elements of other examples are almost the same as in this embodiment, but the present invention
The invention is not limited to the illustrated embodiment.

Hereinafter, the light emitting device of the above embodiment will be described in more detail. As a substrate having the hole injection electrode 2 formed on the transparent substrate 1, a commercially available glass substrate with ITO (manufactured by Sanyo Vacuum Corporation, size 100 × 100 mm × 0.7 mm)
(Thickness) and sheet resistance of about 14Ω / □), and the pattern was formed by photolithography so that the emission area was 1.4 × 1.4 mm due to the overlap with the electron injection electrode. Substrate processing after patterning by photolithography is performed using a commercially available resist stripper (dimethyl sulfoxide and N
-Methyl-2-pyrrolidone) to remove the resist, rinse with acetone, and further immerse in fuming nitric acid for 1 minute to completely remove the resist. Cleaning of the ITO surface is performed sufficiently on both surfaces of the back surface of the substrate, and 0.238 of tetramethylammonium hydroxide is used.
While sufficiently supplying the aqueous solution by weight, mechanical rubbing and cleaning with a nylon brush was performed. Then, it was sufficiently rinsed with pure water and spin-dried. After that, a commercially available plasma reactor (“PR41” manufactured by Yamato Scientific Co., Ltd.)
Inside, oxygen flow rate 20sccm, pressure 26.66Pa
(0.2 Torr) and oxygen plasma treatment for 1 minute under the condition of high frequency output of 300 W.

The substrate with a hole injection electrode prepared as described above was placed in a vacuum chamber. The vacuum evaporation apparatus is a commercially available high vacuum evaporation apparatus ("EBV-6DA" manufactured by Nippon Vacuum Engineering Co., Ltd.).
Type ".) Using the apparatus was modified in main exhaust system turbo molecular pump pumping speed 1500 l / min (Osaka Vacuum Co.," a TC1500 "), ultimate vacuum of about 133.3 × 10 ^{- 6} Pa (about 1 × 10 ^-6 Torr)
r) Below, all depositions are 266.6-399.9
The test was performed in a range of × 10 ⁻⁶ Pa (2 to 3 × 10 ⁻⁶ Torr). In addition, all organic compounds are deposited on a resistance heating type deposition boat made of tungsten with a DC power supply (manufactured by Kikusui Electronics Co., Ltd.
“PAK10-70A”) was connected, and heavy metal deposition was performed by an ion plating apparatus prepared by combining a commercially available electron beam (EB) deposition source with a plasma cracker.

On the substrate with the hole injecting electrode thus arranged in the vacuum layer, N, N'-bis (4'-diphenylamino-4-biphenylyl) -N,
N′-diphenylbenzidine (abbreviation “TPT”, manufactured by Hodogaya Chemical Co., Ltd.) was deposited at a deposition rate of 0.3 (nm / sec).
To deposit 4-N, N-diphenylamino-α-phenylstilbene (abbreviation “PS”) at a deposition rate of 0.01 (nm / s).
ec) to form a blend type hole transport layer 3 having a thickness of about 80 nm.

Next, [4- (2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine (abbreviation) is used as a hole transporting light emitting layer corresponding to the light emitting region 4 in the present invention. “PPDA-PS”) and I
r are 0.3 nm / sec and 0.01 nm / s, respectively.
The film was formed to a thickness of about 40 nm at an ec deposition rate. Most of the Ir dispersed and mixed in the light emitting region was dispersed and mixed as Ir in a single atomic state.

Here, [4- (2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl]
Phenylamine (abbreviation "PPDA-PS") was obtained by synthesis as follows.

In a 300 ml four-necked flask, 41.4 g of N, N'-diphenyl-p-phenylenediamine, 66 g of iodobenzene, 100 ml of nitrobenzene, K ₂ CO ₃
45g, 10.8g of copper powder and I2 (trace)
The mixture was refluxed gently for 24 hours with stirring while distilling off the generated water. Subsequently, steam distillation was carried out. When no distillate was generated, the residue was filtered off after cooling, washed with water and extracted with toluene. After distilling off toluene, ethanol was added to the residue and the mixture was filtered off. Recrystallization was performed using a solvent of toluene: ethanol = 4: 1 (volume ratio), and 36.5 g of N, N, N ′, N ′ was obtained.
-Tetraphenyl-p-phenylenediamine was obtained. m
p = 200-202 <0> C.

Next, 24 g of N-methylformanilide and 20 g of o-dichlorobenzene were placed in a 200 ml four-necked flask.
24 g of POCl ₃ at 25 ° C. (14 m
l) was added dropwise over 1 hour. Then the N, obtained above
36 g of N, N ′, N′-tetraphenyl-p-phenylenediamine was added, and the mixture was further stirred at 90 to 95 ° C. for 2 hours (solidified in the course of o-dichlorobenzene 30).
ml). Cooled after the reaction, which was poured into H ₂ SO ₄ 70 ml of a concentration of 10% by volume, and extracted with toluene. The obtained toluene solution was water, concentration 5% by volume-Na ₂
The organic layer was sequentially washed with a CO ₃ aqueous solution and water, and dried over Na ₂ SO ₄ . The product obtained after distilling off toluene was dissolved in a small amount of toluene, and silica column chromatography was performed. 25.8g
Yellow crystals of p- (N-phenyl-Np'-N ',
(N'-diphenylaminophenyl) aminobenzaldehyde was obtained. mp = 136-138 ° C.

Then, in a 200 ml three-necked flask, 8 g of diethyl-1,1-diphenylmethylphosphonate, p- (N-phenyl-Np'-N ', N'-
Diphenylaminophenyl) aminobenzaldehyde 1
3.3 g of dry N, N-dimethylformamide (DM
F) Dissolved in 80 ml, and added 3.5 g of potassium tert-butoxy (t-BuOK) at 21 to 33 ° C over 30 minutes. Then, stirring was continued at 20 to 25 ° C for 3.5 hours. Next, this solution was poured into 300 ml of ice water while stirring. Toluene extraction, washing with water, alumina column chromatography with toluene solvent after toluene distillation,
0.9 g of [4- (2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine (abbreviation "PPDA-PS") was obtained. mp = 218
~ 219 ° C.

Next, tris (8-quinolinolato) aluminum (abbreviation "Alq3", manufactured by Dojindo Co., Ltd.) was formed as the electron transporting layer 5 at a deposition rate of 0.3 nm / sec to a thickness of about 20 nm.

Next, as the cathode 6, only Li was deposited at low temperature from an AlLi alloy (manufactured by Kojundo Chemical Co., Ltd., Al / Li weight ratio: 99/1) at a deposition rate of about 0.1 nm / s to a thickness of about 1 nm. Then, the temperature of the AlLi alloy was further increased, and from the state where Li was exhausted, only Al was reduced to about 1.5%.
formed to a film thickness of about 100 nm at a deposition rate of nm / sec,
A laminated cathode was used.

The thin-film EL device thus prepared is
After filling the inside of the evaporation tank with dry nitrogen, a lid made of "Corning 7059 glass" (alkali-free borosilicate glass made by Corning Glass Works) is bonded under a dry nitrogen atmosphere to make it less affected by the outside atmosphere. (Manufactured by Anelva Co., Ltd., trade name "Super Back Seal 953-700
0 ") to make a sample.

The thin-film EL element samples thus obtained were evaluated as follows.

The initial evaluation was carried out in a normal laboratory environment at room temperature and normal humidity 12 hours after the glass lid was adhered after the deposition of the device, and at a light emission efficiency (cd / A) of 1000 (cd / m ² ). Were evaluated for drive voltage. The initial luminance is 1000
At a current value of (cd / m ² ), a continuous light emission test was performed in a normal laboratory environment at normal temperature and normal humidity by DC constant current driving. From this test, the time when the luminance reached half (500 cd / m ² ) was evaluated as the life.

As a DC drive power supply, a DC constant current power supply (manufactured by Advantest Co., Ltd., trade name: “Multi-channel current voltage controller TR6163”) was used to measure the voltage-current characteristics, and the luminance was measured by a luminance meter (Tokyo Optical Machinery Co., Ltd.). And the trade name “Topcon luminescence meter BM-8”). Luminance image quality such as uneven brightness and black spots (non-light-emitting portions) was observed with a 50-fold optical microscope.

The pulse drive uses a self-made constant current pulse drive circuit, the pulse cycle is 100 Hz (10 ms), the duty is 1/240 (pulse width 42 μs), the pulse waveform is a square wave, and the pulse current value is set to various values. Was evaluated. The luminance was measured with a luminance meter (trade name “Topcon Luminescence Meter BM-8” manufactured by Tokyo Optical Machine Co., Ltd.), and the pulse drive voltage when the average luminance was 270 (cd / m ² ) was measured. The initial luminance is 270
At a pulse voltage value of (cd / m ² ), continuous pulse driving was performed in a normal laboratory environment at normal temperature and normal humidity to perform a continuous light emission test. The luminance is reduced by half from this test (135 cd / m ² )
Was reached.

The size of the cluster of the heavy metal mixed in the light emitting region, that is, the number of the atoms of the heavy metal contained in the cluster, or the light emitting region such as whether the heavy metal is dispersed and mixed in a single atomic state. The state of the heavy metal particles mixed therein is shown as a TEM (transmission electron microscope) that is often used as a normal thin film analysis method after forming a film as a light emitting region.
The state of heavy metal atoms was observed by observation.

Table 1 shows the results of these evaluations.

According to this embodiment, high luminous efficiency is obtained,
Light emission with excellent visibility is obtained by self-emission at low drive voltage,
Even in the continuous light emission test, a thin-film EL element which has a small decrease in luminance, has no problems such as black spots and luminance unevenness, and can be used stably for an extremely long period of time was realized.

In particular, even during the pulse driving corresponding to the driving of the actual panel, the driving voltage is high and the driving voltage is low, the luminance is small even in the continuous light emission test, there is no problem such as black spots and luminance unevenness, and the operation is performed for an extremely long time. A thin film EL device that can be used stably was realized.

(Example 2) In the formation of the hole transporting light emitting layer of Example 1, [4- (2,2-diphenylvinyl)
Instead of [phenyl] [4- (diphenylamino) phenyl] phenylamine (PPDA-PS), [4-
(2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine (abbreviation "M2PPDA-P
A thin film EL device sample was prepared in the same manner as in Example 1 except that S ″) was used.

Here, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4
-Methoxyphenyl) phenylamino] phenyl diamine (M2PPDA-PS) was synthesized and obtained as follows.

In a 300 ml four-necked flask, 27.6 g of N, N'-diphenyl-p-phenylenediamine, 50 g of p-iodoanisole, 75 ml of nitrobenzene, K ₂
CO ₃ 30 g, placed in copper powder 7.2g and I ₂ (trace), 24 hours gentle reflux under stirring while distilling off formed water. Subsequently, steam distillation was carried out. When no distillate was generated, the residue was cooled and the residue was extracted with toluene. After the toluene was distilled off, the residue was subjected to alumina column chromatography using a toluene solvent. After distilling off the toluene, the residue was recrystallized with a solvent of toluene: ethanol (volume ratio 1: 3) to give 35.3.
g of N, N'-diphenyl-N, N'-bis (p-methoxyphenyl) -p-phenylenediamine were obtained. mp
= 132-134 ° C.

Then, in a 200 ml four-necked flask, 20.4 g of POCl ₃ was added at 25 ° C. in a mixture of 20.4 g of N-methylformanilide and 17 ml of o-dichlorobenzene.
(12 ml) was added dropwise over 1 hour. Next, 35 g of N, N′-diphenyl-N, N′-bis (p-methoxyphenyl) -p-phenylenediamine obtained above was added,
Stirring was further continued at 90 to 95 ° C. for 2 hours. After the reaction was cooled, the reaction solution was poured into a concentration of 10 vol% -H ₂ SO ₄ 70ml, extracted with toluene. The resulting toluene solution is water, a concentration of 5 vol% -Na ₂ CO _3, was washed successively with water, N
a ₂ SO ₄ dried. The product obtained after distilling off toluene was subjected to silica column chromatography using a toluene solvent. After the toluene was distilled off, the residue was recrystallized from ethanol. 1
6.9 g of orange crystals, p- [N- (p-methoxyphenyl) -N- {p-N'-phenyl-N '-(p-methoxyphenyl) aminophenyl}]-aminobenzaldehyde were obtained. mp = 160-161 ° C.

Next, 9.9 was added to a 200 ml three-necked flask with diethyl-1,1-diphenylmethylphosphonate.
g, p- [N- (p-methoxyphenyl)-obtained above.
N- {p-N'-phenyl-N '-(p-methoxyphenyl) aminophenyl}]-aminobenzaldehyde 1
Dissolve 6.4 g in dry DMF (65 ml) and add t-BuOK
4.4 g was added at 21-33 ° C over 30 minutes. Then, stirring was continued at 20 to 25 ° C for 3.5 hours. Then, this was poured into 300 ml of ice water while stirring. This was extracted with toluene, washed with water, and after toluene was distilled off, alumina column chromatography was performed using a toluene solvent to obtain 0.7 g of [4
-(2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine (M2PPDA-PS)
I got mp = 271-272 ° C.

The material thus synthesized was used as a hole transporting light emitting material, and was co-evaporated with Ir in the same manner as in Example 1 to form a hole transporting light emitting layer as a light emitting region of the present invention. Except for the above, a thin film EL device sample was prepared in the same manner as in Example 1, and the evaluation as described in Example 1 was performed.
Most of the Ir dispersed and mixed in the light emitting region was dispersed and mixed as Ir in a single atomic state.

The results are shown in (Table 1).

Example 3 In the formation of the hole transporting light-emitting layer of Example 1, [4- (2,2-diphenylvinyl)
Instead of [phenyl] [4- (diphenylamino) phenyl] phenylamine (PPDA-PS),
{[4- (2,2-diphenylvinyl) phenyl] (4
-(9-anthryl) phenyl) amino @ phenyl) diphenylamine (abbreviation "PPDA-PS-A") and co-evaporated with Ir in the same manner as in Example 1 except that thin film EL device was used. Samples were prepared and evaluated as described in Example 1. (Table 1)
Shown in

Here, (4-{[4- (2,2-diphenylvinyl) phenyl] (4- (9-anthryl) phenyl) amino} phenyl) diphenylamine (PPDA-
PS-A) was obtained by synthesizing as follows.

As a starting material, N-acetyl-1,4-phenylenediamine (N-acetyl-1,4-phenylenediamine) was subjected to Ullmann reaction with iodobenzene, and then hydrolyzed.
Further, 9- (4-iodophenyl) anthracene [9- (4
-iodophenyl) anthracene] to make 4-
(Anthracen-9-yl) phenyl-triphenyl-
Phenylenediamine [4- (anthracene-9-yl) phenyl-trip
henyl-phenylendiamine].

Further, formylation is carried out using the Vilsmeier reaction as shown in the reaction formula of FIG. FIG. 2 is a reaction formula showing the formylation of 4- (anthracen-9-yl) phenyl-triphenyl-phenylenediamine by the Vilsmeier reaction. There have been many reports using dimethylformamide (DMF) in order to obtain high reactivity in formylation. However, since the reaction selectivity is increased and the proportion of the target compound is increased even slightly, N-
Methylformanilide (N-methylformanilide) was used. Since the Vilsmeier reaction is an electrophilic addition, the highest occupied molecular orbital (HOMO) C is the reactive site, and the benzene ring directly bonded to N Is formylated at the p-position. The desired product was extracted by performing sufficient isolation by column development.

Finally, diethyl diphenylmethylphosphonate obtained from diphenylbromomethane and ethyl phosphate was distilled under reduced pressure and then used in the final reaction, and a diphenylvinyl group was allowed to react with the formylated portion as described above.
The compound thus obtained was further sufficiently isolated by column development, and then subjected to further sufficient sublimation purification, and then used for producing a light emitting device.

In general, a vinyl bond is formed by Ullmann
Since it seems that the reaction does not endure the high temperature of the reaction, an example of synthesis from a route in which a skeleton is first obtained by the Ullmann reaction, then formylated by the Vilsmeier reaction, and finally a diphenylvinyl group is added is shown. As shown,
There is also a method in which coupling with an anthracene moiety is performed last using a Pd catalyst or the like to obtain a higher yield. In this case, similar results were obtained as the light emitting device characteristics.

The Ir dispersed and mixed in the light emitting region
Was mostly dispersed and mixed as Ir in a single atomic state.

Example 4 In the formation of the hole transporting light-emitting layer of Example 1, [4- (2,2-diphenylvinyl)
Instead of [phenyl] [4- (diphenylamino) phenyl] phenylamine (PPDA-PS),
{[4- (2,2-diphenylvinyl) phenyl] [4
-(10-methoxy (9-anthryl)) phenyl] amino} phenyl) diphenylamine (abbreviation "PPDA-
Using PS-AM ″), a thin film EL device sample was prepared in the same manner as in Example 1 except that co-evaporation with Ir was performed in the same manner as in Example 1, and the evaluation as described in Example 1 was performed.
The results are shown in (Table 1).

Here, (4-{[4- (2,2-diphenylvinyl) phenyl] [4- (10-methoxy (9-anthryl)) phenyl] amino} phenyl) diphenylamine (PPDA-PS-AM) It was obtained by synthesizing as follows.

The 9- (4-iodophenyl) anthracene used in Example 3 was used.
ne] instead of 10- (4-iodophenyl) -9-
Methoxyanthracene [10- (4-iodophenyl) -9-methoxya
nthracene], except that the synthesis was carried out in the same manner as in Example 3. This compound also has a Pd
There is also a method in which coupling with an anthracene moiety is performed last using a catalyst or the like to obtain a higher yield. In this case, similar results were obtained as the light emitting device characteristics.

The Ir dispersed and mixed in the light emitting region
Was mostly dispersed and mixed as Ir in a single atomic state.

Example 5 A thin film EL device sample was prepared in the same manner as in Example 1 except that Pt was used instead of Ir in forming the hole transporting light emitting layer of Example 3.
The evaluation as described in Example 1 was performed. Most of Pt dispersed and mixed in the light emitting region was dispersed and mixed as Pt in a single atomic state.

Table 1 shows the results.

Example 6 A thin-film EL device sample was prepared in the same manner as in Example 1 except that Au was used instead of Ir in forming the hole-transporting light-emitting layer of Example 3.
The evaluation as described in Example 1 was performed. Most of Au dispersed and mixed in the light emitting region was dispersed and mixed as Au in a single atomic state.

Table 1 shows the results.

Example 7 A thin film EL device sample was prepared in the same manner as in Example 1 except that La was used instead of Ir in the formation of the hole transporting light emitting layer of Example 3.
The evaluation as described in Example 1 was performed. Most of La dispersed and mixed in the light emitting region was dispersed and mixed as La in a single atomic state.

Table 1 shows the results.

Example 8 A thin film EL device sample was prepared in the same manner as in Example 1 except that Tb was used instead of Ir in forming the hole transporting light emitting layer of Example 3.
The evaluation as described in Example 1 was performed. Most of the Tb dispersed and mixed in the light emitting region was dispersed and mixed as Tb in a single atomic state.

Table 1 shows the results.

Example 9 A thin film EL device sample was prepared in the same manner as in Example 1 except that the hole transporting light emitting layer of Example 1 was formed as described below, and described in Example 1. Was evaluated as follows.

Table 1 shows the results.

Here, the hole transporting light emitting layer corresponding to the light emitting region according to the present invention was formed as follows.

The compound 4, which can sustain charge transport,
4'-bis (carbazol-9yl) biphenyl (abbreviation "CBP", manufactured by Chemipro Kasei Co., Ltd.) and [2-methyl-6- [2- (2,3,6,7-tetrahidero-) 1H, 5H-benzo [ij] quinolidine-9
-Yl) ethenyl] -4H-pyran-4-ylidene] propene-dinitrile (abbreviation "DCM2", manufactured by Kodak Co., Ltd.) and Ir at 0.3 nm / sec, respectively.
The film was formed to a thickness of about 40 nm at a deposition rate of 0.01 nm / sec and 0.01 nm / sec. Ir deposition was performed by an ion plating apparatus prepared by combining an electron beam (EB) deposition source with a plasma cracker, as in Example 1.

The Ir dispersed and mixed in the light emitting region
Was mostly dispersed and mixed as Ir in a single atomic state.

(Comparative Example 1) In the formation of the hole transporting light emitting layer of Example 1, [4- (2,
2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine (PPDA-PS)
A thin film EL device sample was prepared in the same manner as in Example 1 except that only the sample was used, and evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 2) In the formation of the hole-transporting light emitting layer of Example 2, [4- (2,
Thin film EL device in the same manner as in Example 2 except that only 2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine (M2PPDA-PS) was used. Samples were prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 3) In forming the hole transporting light emitting layer of Example 1, Ba was replaced with [4- (2,2) instead of Ir.
A thin-film EL device sample was prepared in the same manner as in Example 1 except that co-evaporation was performed together with -diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine (PPDA-PS). The evaluation was performed as described. The results are shown in (Table 1).

The Ba dispersed and mixed in the light emitting region
Was mostly dispersed and mixed as Ba in a single atomic state.

Comparative Example 4 In the formation of the hole transporting light emitting layer of Example 2, Ba was replaced by [4- (2,2) instead of Ir.
-Diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine (M2PPDA-PS) Example 2
In the same manner as in Example 1, a thin film EL element sample was prepared.
The evaluation as described in was performed. The results are shown in (Table 1).

The Ba dispersed and mixed in the light emitting region
Was mostly dispersed and mixed as Ba in a single atomic state.

(Comparative Example 5) In the formation of the hole transporting light emitting layer of Example 9, Ir co-evaporation was not performed, and 4,4'-bis (carbazol-9yl) biphenyl (CBP, Chemiplo Chemical Co., Ltd.) was used. ) And [2-methyl-6- [2-
(2,3,6,7-tetrahidelo-1H, 5H-benzo [ij] quinolizin-9-yl) ethenyl] -4H-pyran-4-ylidene] propene-dinitrile (DCM
2, Kodak Co., Ltd.), except that only a thin-film EL element sample was prepared in the same manner as in Example 9.
The evaluation as described in was performed. The results are shown in (Table 1).

[0150]

[Table 1]

In Table 1, the device configurations of the respective examples and comparative examples are abbreviated by abbreviations.
N, N′-bis (4′-diphenylamino-4-biphenylyl) -N, N′-diphenylbenzidine, PS is
4-N, N-diphenylamino-α-phenylstilbene, PPDA-PS is [4- (2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine, M2PPDA-PS is [ 4-
(2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine, PPDA-PS-A
(4-{[4- (2,2-diphenylvinyl) phenyl] (4- (9-anthryl) phenyl) amino} phenyl) diphenylamine, PPDA-PS-AM
(4-{[4- (2,2-diphenylvinyl) phenyl] [4- (10-methoxy (9-anthryl)) phenyl] amino} phenyl) diphenylamine, Alq3
Is tris (8-quinolinolato) aluminum, CBP
Is 4,4′-bis (carbazol-9yl) biphenyl, and DCM2 is [2-methyl-6- [2- (2,3,
6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl) ethenyl] -4H-pyran-4-
Ilidene] propene-dinitrile, Al is aluminum, Li is lithium, Ir is iridium, Pt is
Platinum, Au represents gold, La represents lanthanum, Tb represents terbium, and Ba represents barium, and is described in order from the ITO electrode side, separated from each other by / as a symbol indicating a laminated configuration from the left. Numbers in parentheses indicate film thickness in nm, and + indicates a coexisting film of both components such as doping mixture.

[0152]

As described above, the light emitting device according to the present invention, the method for manufacturing the same, and the display device using the same have been described. However, the present invention relates to a light emitting device in which an organic light emitting layer contains a heavy metal as a mixture. By doing,
A light-emitting element having a light-emitting region disposed between at least a pair of electrodes, wherein the light-emitting region contains (A) a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal as a mixture; B) a compound capable of sustaining charge transport, which compound contains both a portion mainly contributing to charge transport and a portion contributing to light emission, and a heavy metal as a mixture, or In each of A) or (B),
Each light emitting region has high luminous efficiency, has no defects such as unevenness or black spots, and emits light at a low driving voltage by forming a layer made of a mixture of the above materials by simultaneously depositing the above-described constituent components. Thus, a thin-film EL element that can be used stably for a very long time with small power consumption and small power consumption even in a continuous light emission test can be obtained.

Also, even in the case of pulse driving corresponding to actual driving by a passive matrix panel, it has a low driving voltage, high efficiency, and high reliability, can be used stably for a very long time with little power consumption. This can realize a thin film EL element.

More preferably, the compound capable of sustaining charge transport has both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound, and more preferably, it has a hole transporting property. By being a light-emitting material, more preferably, the content ratio of heavy metals in the light-emitting region is 0.1 mol% or more with respect to the light-emitting material or a compound having both a portion contributing to charge transport and a portion contributing to light emission. By being 50 mol% or less, or more preferably, in the light emitting region, the heavy metal is in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average of 10 or less atoms of the heavy metal on average. Heavy metal, preferably a cluster having an average number of atomic particles of the heavy metal and 5 or less atoms of the heavy metal As the ultrafine particulate heavy metal selected from the child, by the heavy metal particles are mixed in as small as possible state, etc. In either case improving the luminous efficiency, more remarkable effect can be exhibited.

Therefore, the present invention can provide a useful thin-film EL device, and the thin-film EL device of the present invention can be used as various light sources used for communication, illumination, and other applications, such as a flat type self-luminous display device. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of an organic thin-film electroluminescence device that is a light-emitting device of the present invention.

[Fig. 2] 4 by the Vilsmeier reaction
The figure which shows the reaction formula which shows the formylation of-(anthracen-9-yl) phenyl-triphenyl-phenylenediamine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent substrate 2 hole injection electrode 3 hole transport layer 4 light emitting region (hole transporting light emitting layer) 5 electron transport layer 6 cathode

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hisanori Sugiura 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 3K007 AB03 AB06 AB11 AB17 AB18 DB03 FA01

Claims (27)

[Claims] 1. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region includes a light-emitting material,
A light-emitting element containing a compound capable of sustaining charge transport and a heavy metal as a mixture. 2. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region includes a light-emitting material,
A light-emitting element comprising a mixture of materials obtained by simultaneously depositing a compound capable of sustaining charge transport and a heavy metal. 3. The light emitting device according to claim 1, wherein a content ratio of the heavy metal in the light emitting region is 0.1 mol% to 50 mol% with respect to the light emitting material. 4. The mixed heavy metal according to claim 1, wherein the mixed heavy metal is a heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average of 10 or less atoms of the heavy metal. A light-emitting element according to any one of the above. 5. The mixed heavy metal according to claim 1, wherein the mixed heavy metal is an ultrafine particulate heavy metal selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. A light-emitting element according to any one of the above. 6. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport in the compound and contributing to light emission. A light-emitting element containing, as a mixture, a compound having both a compound and a heavy metal. 7. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport in the compound and contributing to light emission. A light-emitting element comprising a mixture of a compound obtained by simultaneously depositing a compound having a portion to be treated and a heavy metal. 8. The compound capable of sustaining charge transport comprises a hole-transporting luminescent material having both a portion mainly contributing to charge transport and a portion contributing to light emission in the compound.
Or the light-emitting element according to 7. 9. The heavy metal content ratio in the light emitting region is as follows:
0.1 mol% to 50 mol of a compound capable of sustaining charge transport and having a portion mainly contributing to charge transport and a portion contributing to light emission in the compound.
%. The light emitting device according to claim 6, wherein 10. The mixed heavy metal according to claim 6, wherein the mixed heavy metal is an ultrafine particulate heavy metal selected from atomic particles of the heavy metal and cluster particles having an average of 10 or less atoms of the heavy metal. A light-emitting element according to any one of the above. 11. The mixed heavy metal according to any one of claims 6 to 9, wherein the mixed heavy metal is an ultrafine particulate heavy metal selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. A light-emitting element according to any one of the above. 12. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region contains, as a mixture, a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal. A light-emitting element in which the ratio of light emission to recombination of unit charges is increased as compared with the case where the light-emitting material is composed only of a mixture of a light-emitting material and a compound capable of sustaining charge transport. 13. A light-emitting element having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region is a compound capable of sustaining charge transport, and a portion of the compound mainly contributing to charge transport and contributing to light emission. A compound having both a portion and a heavy metal, as a mixture, the light-emitting region is a compound capable of sustaining charge transport, and a portion mainly contributing to charge transport and a portion contributing to light emission in the compound. A light-emitting element in which the ratio of light emission to recombination of unit charges is increased as compared to the case where the light-emitting element includes only a compound having the light-emitting element. 14. The mixed heavy metal according to claim 12 or 13, wherein the mixed heavy metal is an ultrafine particle-shaped heavy metal selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 10 or less. Light emitting element. 15. The mixed heavy metal according to claim 12 or 13, wherein the mixed heavy metal is a heavy metal in the form of ultrafine particles selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. Light emitting element. 16. The light emitting device according to claim 1, wherein the heavy metal is mainly a metal having an atomic number of 57 or more. 17. A method for manufacturing a light-emitting element having at least a light-emitting region between a pair of electrodes, wherein at least one layer in the light-emitting region includes a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal. And a method for manufacturing a light-emitting element in which a film is formed by simultaneous deposition. 18. The method according to claim 17, wherein the heavy metal is deposited through cracking means. 19. A method for manufacturing a light-emitting element having at least a light-emitting region between a pair of electrodes, wherein at least one layer in the light-emitting region is a compound capable of sustaining charge transport, wherein the compound mainly contains a charge. A method for manufacturing a light-emitting element in which a compound having both a portion contributing to transport and a portion contributing to light emission and a heavy metal are simultaneously deposited to form a film. 20. The method according to claim 19, wherein the heavy metal is deposited through cracking means. 21. The method according to claim 17, wherein the heavy metal is mainly a metal having an atomic number of 57 or more. 22. A display device using a plurality of light-emitting elements having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region in the light-emitting element includes a light-emitting material, a compound capable of sustaining charge transport, and a heavy metal. Comprising a light-emitting region containing as a mixture. 23. A display device using a plurality of light-emitting elements each having at least a light-emitting region between a pair of electrodes, wherein the light-emitting region in the light-emitting element is a compound capable of sustaining charge transport, and mainly includes a compound in the compound. A display device comprising a light-emitting region containing a compound having both a portion contributing to charge transport and a portion contributing to light emission and a heavy metal as a mixture. 24. The mixed heavy metal according to claim 22 or 23, wherein the mixed heavy metal is an ultrafine particulate heavy metal selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 10 or less. Display device. 25. The mixed heavy metal according to claim 22 or 23, wherein the mixed heavy metal is an ultrafine particle-shaped heavy metal selected from atomic particles of the heavy metal and cluster particles having an average number of atoms of the heavy metal of 5 or less. Display device. 26. The display device according to claim 22, wherein the heavy metal is mainly a metal having an atomic number of 57 or more. 27. A light emitting device comprising a heavy metal as a mixture in an organic light emitting layer.