CN1781340A - organic electroluminescent element - Google Patents

Abstract

The present invention provides: an organic electroluminescent element having a longer life than conventional elements, wherein the anode is provided with at least a light-emitting layer, an electron injection transport layer and a cathode; an organic electroluminescent element having a whiteness degree superior to that of the conventional organic electroluminescent element, a high luminous efficiency and a long element life; and a color display device using the organic electroluminescent element. In which a hole injection transport layer 11, a light emitting layer 12, a non-light emitting layer 13, an electron injection transport layer 14 and a cathode 15 are sequentially stacked on an anode 10. Or a hole injection layer, a hole transport layer, a red light emitting layer, a blue light emitting layer, an electron transport layer, an electron injection layer and a cathode are sequentially stacked on the anode.

Description

organic electroluminescent element

technical field

The invention relates to an organic electroluminescence element which is at least provided with a light-emitting layer, an electron injection transport layer and a cathode on the anode. The present invention also relates to an organic electroluminescence element in which at least an organic light-emitting layer and a cathode are sequentially provided on the anode.

Background technique

Conventionally, there is known an organic electroluminescence element (organic EL element) in which a light-emitting layer containing an organic light-emitting material is provided between opposing electrodes, a current flows between the electrodes, and light (electroluminescence) is emitted from the light-emitting layer. Its light-emitting layer is required to have the following functions.

·Electron injection function

The function of injecting electrons from the electrode (cathode). Electron injection.

·Hole injection function

The function of injecting holes from the electrode (anode). hole injection.

· Carrier transport function

A function of transporting at least one of electrons and holes. carrier transport.

The function of transporting electrons is called electron transport function (electron transport property), and the function of transporting holes is called hole transport function (hole transport property).

·Lighting function

The injected and transported electrons recombine with carriers to generate excitons, and emit light when returning to the ground state.

It is known in the prior art that a layer performing one or more of the above-mentioned functions is provided separately from the light-emitting layer. For example, a conventional technique is known to provide a layer (electron injection and transport layer) having an electron injection function and an electron transport function (for example, refer to Japanese Patent Application Laid-Open No. 2002-164174). By providing the electron injection transport layer separately from the light-emitting layer (separating the function), the following effects can generally be obtained.

・Driving voltage drop

・Electron injection from the cathode to the light-emitting layer is stable, so the life is long

・The adhesion between the cathode and the light-emitting layer is improved, so the uniformity of the light-emitting surface can be improved

・It can reduce device defects by covering the protrusions of the cathode, etc.

In recent years, great expectations have been placed on organic electroluminescence elements for application to full-color display devices. As a method of using an organic electroluminescent element for full-color display, it is known to divide the white light emitted by the organic electroluminescent element into red, green, and blue light through a color filter. The organic electroluminescent element used here is required to have the following characteristic.

Good balance of red, green and blue luminous intensities

·High luminous efficiency

· Long component life.

Therefore, as an organic electroluminescent element with a relatively good balance of red, green, and blue luminous intensities, there is known an organic electroluminescent element in which a blue light-emitting layer and a green light-emitting layer are sequentially provided as an organic light-emitting element from the anode side. A light-emitting layer, and the green light-emitting layer contains a red light-emitting dopant (for example, refer to Japanese Patent Application Laid-Open No. 7-142169).

Contents of the invention

However, it is also difficult to obtain a sufficient life (device life) in practical use in an organic EL device in which a layer having an electron injection function or an electron transport function is provided separately from the light emitting layer.

In addition, conventional organic electroluminescent elements emitting white light have problems of poor whiteness, low luminous efficiency, and short device life.

In view of the above problems, the present invention aims to extend the life (device life) of an organic electroluminescent device having at least a light-emitting layer, an electron injection transport layer, and a cathode provided on the anode more than conventionally.

In view of the above problems, the present invention aims to improve the whiteness, luminous efficiency, and device life of an organic electroluminescence device in which at least an organic light-emitting layer and a cathode are sequentially provided on the anode.

In order to achieve the above object, the organic electroluminescent element of the present invention is characterized in that: a light-emitting layer, an electron injection transport layer and a cathode are arranged on the anode, and an electron transport layer having electron transport properties and a hole electrode is provided between the electron injection transport layer and the light-emitting layer. A non-emitting layer having higher transport properties than the electron injection transport layer (a non-emitting carrier balance adjustment layer). The electron injection transport layer may be composed of a single layer or may be composed of laminated layers. For example, the electron injection transport layer can be composed of an electron injection layer and an electron transport layer.

High/low electron-transportability and hole-transportability can be known, for example, by the time-of-flight method (TOF method). What is obtained by the TOF method is the mobility of carriers (cm ² /V·s), which can be calculated from the transient current, the voltage applied to the sample, and the thickness of the sample, where the transient current is applied by irradiation with pulsed light The voltage across the sample surface is generated when the carriers generated by the pulsed light move through the sample (intralayer). Specifically, a separate film (for example, a layer of about 10 to 20 μm) of the layer whose electron-transport property/hole-transport property is to be measured is produced, and the carrier mobility is measured using this film. The electron-transport property/hole-transport property of each material is evaluated as follows: A layer (for example, a film of about 10-20 μm) containing only the material is produced, and the carrier mobility is measured using the layer, and the carrier mobility is used to determine Electron transport properties/hole transport properties were evaluated. The conditions for the applied electric field strength when measuring the carrier mobility are within the range of the electric field strength applied when the organic EL element is actually used.

Therefore, the above-mentioned organic electroluminescent element also includes the following organic electroluminescent element: a light-emitting layer, an electron injection transport layer, and a cathode are arranged on the anode, and an electron transport and hole transport layer is provided between the electron injection transport layer and the light-emitting layer. Non-emitting layer, the hole mobility specified by the TOF method of the non-emitting layer is higher than the hole mobility specified by the TOF method of the electron injection transport layer.

In the present specification, "having electron-transport property" means that the electron-transport property is at least higher than that of the member/layer closer to the anode side of the light-emitting layer, and preferably higher than the electron-transport property of the light-emitting layer. Of course, the electron transport property may be equal to or higher than that of the electron injection transport layer.

The electron-transport property of the non-emitting layer of the above-mentioned organic electroluminescent element may be higher (exceeded, greater) than the hole-transport property. For example, the electron mobility defined by the TOF method of the non-emitting layer is preferably higher than the hole mobility defined by the TOF method.

The non-emitting layer in the first or second organic electroluminescence element may contain the following (1) or (2) material.

(1) A material having electron transport properties and a hole transport property higher than that of the electron injection transport layer.

Examples include materials having electron-transporting properties and hole-transporting properties, and having a hole mobility defined by the TOF method higher than that defined by the TOF method of the electron injection transport layer.

(2) One or more electron transport materials having electron transport properties, and one or more hole transport materials having higher hole transport properties than the electron injection transport layer.

For example, the hole-transporting material includes one or more materials whose hole mobility defined by the TOF method is higher than the electron mobility of the electron-transporting material defined by the TOF method.

In (2) above, at least one of the electron-transporting materials may be the same material as at least one of the materials contained in the electron injection transport layer, or/further, at least one of the hole-transporting materials may be the same as At least one of the materials contained in the light-emitting layer is the same material.

In the above (2), the electron-transporting property of the electron-transporting material may be higher than the hole-transporting property of the hole-transporting material. For example, the electron mobility determined by the TOF method of the electron transport material may be higher than the hole mobility determined by the TOF method of the hole transport material.

The organic electroluminescent device of the present invention is particularly suitable for a device in which the light-emitting layer is hole-transporting, that is, the hole-transporting property is higher than the electron-transporting property.

The ambipolar material in this specification refers to a material whose hole mobility and electron mobility are both 10 ^-8 cm ² /V·s or more within the range of the applied electric field strength in the actual application of the organic EL device.

The organic electroluminescent element of the present invention is characterized in that: an organic light-emitting layer and a cathode are at least sequentially arranged on the anode, a red light-emitting layer and a blue light-emitting layer are sequentially arranged on the organic light-emitting layer from the side of the anode, and the red light-emitting layer contains green light-emitting dopant.

The emission spectrum of the above-mentioned organic electroluminescent element preferably has a maximum in the region of 440 nm or more but 490 nm or less, 510 nm or more but 550 nm or less, and 580 nm or more but 680 nm or less.

A light emission adjustment layer may be provided between the red light emitting layer and the blue light emitting layer. As a result, whiteness, luminous efficiency, and device life are further improved. Furthermore, it is preferable that the thickness of the blue light-emitting layer is greater than the thickness of the red light-emitting layer. The "emission adjusting layer" herein refers to a layer that adjusts the luminescence intensity ratio of a luminescent material.

Preferably, the above-mentioned red light emitting layer contains at least one kind of red light emitting dopant.

It is desirable that the hole mobility of the red light emitting layer is higher than that of the blue light emitting layer.

The color display device of the present invention is characterized by comprising the above-mentioned organic electroluminescent element, and at least one type of filter that absorbs a part of the emission spectrum of the organic electroluminescent element. Preferably, the light-emitting region of the organic electroluminescent element is within the transmissive region of the filter.

According to the present invention, the lifetime of an organic electroluminescent element having a light-emitting layer, an electron injection transport layer, and a cathode provided on an anode can be extended longer than that of a conventional organic electroluminescent element without the structure of the present invention.

According to the present invention, the whiteness, luminous efficiency, and device life of an organic electroluminescent element in which at least an organic light-emitting layer and a cathode are sequentially provided on the anode can be improved more than conventional organic electroluminescent elements that do not adopt the structure of the present invention.

Brief description of the drawings

FIG. 1 is a cross-sectional view for explaining an example of a layer configuration of an organic electroluminescence element according to a first embodiment.

Fig. 2 is a cross-sectional view illustrating a layer configuration example of a modified example of the organic electroluminescent element of the first embodiment.

Fig. 3 is a cross-sectional view showing a layer configuration of a modified example of the organic electroluminescent element of the first embodiment.

Fig. 4 is a cross-sectional view showing a layer configuration of a modified example of the organic electroluminescent element of the first embodiment.

Fig. 5 is a cross-sectional view illustrating an example of a layer configuration of an organic electroluminescence element according to a second embodiment.

6 is a schematic configuration diagram of the overall configuration of a color display device.

FIG. 7 is a schematic cross-sectional view of an organic electroluminescent panel used in the color display device of FIG. 6 .

8 is a table showing transmission peak wavelengths and half widths thereof of color filters used in the color display device of FIG. 6 , and emission peak wavelengths and half widths thereof of organic electroluminescence elements.

The best way to practice the invention

Hereinafter, an organic EL device according to an embodiment of the present invention will be described in detail with reference to the drawings.

first embodiment

"Layer Composition"

The organic EL element of the first embodiment is constituted by forming at least a light-emitting layer, a non-light-emitting layer, an electron injection transport layer, and a cathode in this order on an anode. That is, it is characterized in that the non-light-emitting layer of the present invention is provided between the light-emitting layer and the electron injection transport layer.

Next, according to the organic EL shown in FIG. 1, an anode 10 is formed on a substrate 2, and a hole injection transport layer 11, a light emitting layer 12, a non-light emitting layer 13, an electron injection transport layer 14, and a cathode 15 are sequentially formed on the anode 10. The components are described, and other types of layer configurations are of course also applicable.

For example, it is possible to make the light-emitting layer have the function of a hole injection transport layer, that is, a hole injection function and a hole transport function, thereby omitting the hole injection transport layer; The electron injection layer and the electron transport layer having the function of electron injection are laminated; more specifically, the following layer constitution can be employed.

Anode/hole injection layer/hole transport layer/light-emitting layer/non-light-emitting layer/electron transport layer/electron injection layer/cathode

Anode/hole injection layer/hole transport layer/light emitting layer/non-light emitting layer/electron injection transport layer/cathode

Anode/hole injection transport layer/light emitting layer/non-light emitting layer/electron transport layer/electron injection layer/cathode

Anode/hole injection transport layer/light emitting layer/non-light emitting layer/electron injection transport layer/cathode

Anode/hole transport layer/light emitting layer/non-light emitting layer/electron transport layer/electron injection layer/cathode

·Anode/hole transport layer/emissive layer/non-emissive layer/electron injection transport layer/cathode

·Anode/Emitting layer/Non-emitting layer/Electron transport layer/Electron injection layer/Cathode

·Anode/Emitting layer/Non-emitting layer/Electron injection transport layer/Cathode

Each of the above layers may have functions other than the above, for example, the light emitting layer may have a hole transport function, a hole injection function, an electron injection function and/or an electron transport function.

Layers other than those described above may also be appropriately provided.

Of course, cathodes may be sequentially stacked on a substrate to form an organic EL element.

In this specification, the layers provided between the non-emissive layer and the cathode are collectively referred to as an electron injection transport layer.

First, the non-emitting layer will be described in detail.

"Non-luminous layer 13"

The non-emitting layer 13 is provided between the electron injection transport layer 14 and the light emitting layer 12 , has electron transport properties, and has higher hole transport properties than the electron injection transport layer 14 , and does not have a light emitting function.

Electron-transport and hole-transport properties can be specified, for example, by the TOF method. That is, the non-light emitting layer 13 can be said to be a layer as shown below.

A layer having a hole mobility measured by the TOF method higher than the hole mobility of the electron injection transport layer 14 defined by the TOF method.

• A layer that adjusts the balance of carriers (holes and electrons) in the light emitting layer 12 (carrier balance adjustment layer).

• A layer that does not have a light-emitting function.

<mechanism>

The organic EL element of this embodiment includes the non-emitting layer 13 as described above, so the lifetime of the element is longer than conventional ones. The reason (mechanism) is presumed to be the following mechanism 1 or mechanism 2.

(Mechanism 1)

It is considered that it is difficult for holes or excitons to enter the electron injection transport layer 14, so that the deterioration of the electron injection transport layer 14 is reduced compared to conventional ones, and as a result, the lifetime of the device is prolonged.

In a conventional organic EL device, some of the holes injected and transported from the anode side to the light emitting layer recombine with electrons in the light emitting layer and enter the electron injection transport layer. On the other hand, the electron injection transport material contained in the electron injection transport layer has extremely low hole transport properties, and therefore has low tolerance to holes. Therefore, it is considered that once holes enter the electron injection transport layer, the electron injection transport layer or the electron injection transport material in the layer deteriorates.

In addition, in the conventional organic EL element, the holes that entered recombine with the electrons injected and transported from the cathode side to generate excitons, or the excitons entered from the light-emitting layer side, and electrons were injected into the transport layer or the transport layer due to the excitons. The electron injection transport material within the layer deteriorates.

On the other hand, in the non-emitting layer 13 of the present embodiment, the hole-transport property is higher than that of the electron injection-transport layer 14 , and thus the resistance to incoming holes or excitons is higher than that of the electron-injection-transport layer 14 .

In addition, the non-light-emitting layer 13 has electron-transport properties, so electrons transported by the electron injection transport layer 14 can be transported into the light-emitting layer 12 . In other words, almost all holes and electrons are recombined in the light-emitting layer 12 and the non-light-emitting layer 13, so compared with the conventional element that does not have the non-light-emitting layer 13, recombination in the electron injection transport layer 14 and hole entry Injection of electrons into the transport layer 14 is reduced.

In this way, it is difficult for holes or excitons to enter the electron injection transport layer 14 that is strongly degraded by holes or excitons, and the non-emitting layer 13 is more resistant to holes or excitons than the electron injection transport layer 14, so it does not The deterioration of the light emitting layer 13 and the electron injection transport layer 14 is reduced compared with the deterioration of the electron injection transport layer 14 in the conventional device. As a result, the device life of the organic EL device of this embodiment is prolonged.

(Mechanism 2)

The non-emitting layer 13 has hole-transport and electron-transport properties, so excitons accumulate (existence probability is high, increase) at the interface of the electron injection transport layer 14 (the interface on the opposite side to the cathode 15, hereinafter appropriately referred to as "electron injection transport"). The interface ") of the layer 14 is reduced, and the deterioration of the electron injection transport layer 14 is reduced compared to the conventional one. Therefore, it can be considered that this can prolong the life of the element than before.

Conventionally, the interface of the electron injection transport layer and the vicinity of the interface are known to have many excitons, and the electron injection transport layer is easily deteriorated.

On the other hand, as described above, the electron injection transport layer has almost no hole transport properties, so a large number of holes transported from the light emitting layer to the electron injection transport layer side exist at the interface of the electron injection transport layer and in the vicinity of the interface. Therefore, electrons injected and transported from the cathode side combine with the holes to generate excitons at the interface of the electron injection transport layer and in the vicinity of the interface.

Therefore, in conventional organic EL devices, excitons tend to accumulate at the interface and near the interface of the electron injection transport layer, so the electron injection transport layer tends to deteriorate. As a result, it can be said that it is difficult to obtain a sufficient device life.

On the other hand, the non-emitting layer 13 of this embodiment has higher hole-transportability than the electron injection transport layer 14, so holes can be transported from the interface (and near the interface) between the non-emitting layer 13 and the light-emitting layer 12 to the electron injection transport layer 14. Electrons are injected into the transport layer 14 side. In addition, the non-emitting layer 13 also has electron transport properties, therefore, the electrons transported by the electron injection transport layer 14 can be transported to the light-emitting layer 12, and at the same time, the holes that move in the non-emitting layer 13 can be transported in the non-emitting layer 13. Recombine with electrons to produce excitons. That is to say, the amount of excitons existing at the interface between the electron injection transport layer 14 and the non-luminescent layer 13 and the vicinity of the interface can be made larger than that of the electron injection transport layer and the light-emitting layer in the organic EL element without the non-light-emitting layer 13 in the past. The amount of excitons existing at the interface and in the vicinity of the interface is small. Therefore, in the organic EL element of this embodiment, the deterioration of the electron injection transport layer 14 is less than that of the conventional organic EL element, and as a result, the lifetime can be extended compared with the conventional organic EL element.

The above mechanism can be said to be that the non-emitting layer 13 increases the electron transport property relative to the hole transport property by making the electron mobility determined by the TOF method higher than the hole mobility determined by the TOF method.

Such a configuration can make the amount/speed of electrons transported by the electron injection transport layer 14 moving to the light emitting layer 12 in the non-light emitting layer 13 be greater than the amount/speed of the holes entering the electron injection transport layer 14 from the light emitting layer 12. big. Therefore, the entry of holes or excitons into the electron injection transport layer 14 is further reduced, and the accumulation of holes at and near the interface of the electron injection transport layer 14 (increased probability of exciton existence) is further reduced. Therefore, deterioration of the electron injection transport layer 14 can be further reduced, and the device life of the organic EL device can be further extended.

As described above, by increasing the electron mobility in the non-emitting layer 13, the luminous efficiency can be further improved.

Furthermore, according to the above configuration, the ratio of recombination of holes and electrons in the light-emitting layer 12 can be increased more than conventionally, so that the luminous efficiency can be improved more than conventionally.

The non-light emitting layer 13 may be formed of a single material or may be formed of a plurality of materials. Hereinafter, the materials contained in the non-emitting layer 13 and the method of producing the non-emitting layer 13 will be described.

<composed of a single material>

When the non-emitting layer 13 is made of a single material, a material that imparts electron transport properties to the non-luminescent layer 13 and higher hole transport properties than the electron injection transport layer 14 (the material constituting the electron injection transport layer 14 ) can be used. For example, the material has electron transport properties and has a higher hole mobility defined by the TOF method than that of the electron injection transport layer 14 defined by the TOF method. More specifically, it can be appropriately selected from the following materials.

Distyryl arylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinoline alcoholate metal complexes, triarylamine derivatives, azomethine derivatives, oxadi Azole derivatives, pyrazoquinoline derivatives, silol derivatives, bicarbazole derivatives, oligothiophene derivatives, tetraphenylbutadiene derivatives, benzopyran Derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, tris(8-hydroxyquinoline)aluminum, N,N'-bis(4'-diphenylamino-4-biphenyl base)-N,N'-diphenylbenzidine, 4,4'-bis(2,2'-diphenylvinyl)biphenyl, etc.

Among these materials, it is preferable to select a material that does not emit light when forming the non-luminescent layer 13 . The reason is that if the non-emitting layer 13 emits light by any chance, the chromaticity of the light emitted by the light-emitting layer 12 will be impaired.

<composed of various materials>

When making the non-emitting layer 13 from multiple materials, at least one or more electron transport materials with electron transport properties and one or more hole transport properties with higher hole transport properties than the electron injection transport layer 14 are selected. Transportable material. The hole-transporting material may be a material having a higher hole mobility as defined by the TOF method than that of the electron-transporting material contained in the non-emitting layer 13 as defined by the TOF method.

The electron-transporting property of the electron-transporting material can be made larger than the hole-transporting property of the hole-transporting material. For example, when selecting materials, the electron mobility of the electron transport material specified by the TOF method is larger than the hole mobility of the hole transport material specified by the TOF method, then in the non-emitting layer 13, the electron mobility exceeds the hole mobility. rate, so the above effects can be obtained.

The electron-transporting material may be any material as long as it has the above properties, and it may be selected from the following materials, for example.

1,3-bis[5'-(p-tert-butylphenyl)-1,3,4-oxadiazol-2'-yl]benzene or 2-(4-biphenyl)-5-(4- tert-butylphenyl)-1,3,4-oxadiazole and other oxadiazole derivatives; or 3-(4'-tert-butylphenyl)-4-phenyl-5-(4"-biphenyl )-1,2,4-triazole and other triazole derivatives, etc.

Triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorenone derivatives, thiopyran derivatives, anthraquinone dimethane metan) derivatives, thiopyran derivatives, heterocyclic tetracarboxylic anhydrides such as naphthalene perylene, carbodiimide, fluorenylidene methane derivatives, anthraquinone dimethane derivatives, anthrone derivatives, distyryl pyrazine derivatives, etc.

Bis(10-benzo[h]quinolinol) beryllium, beryllium salt of 5-hydroxyflavone, aluminum salt of 5-hydroxyflavone and other organometallic complexes, metal complexes of 8-hydroxyquinoline or its derivatives things etc. More specifically, there are metal chelate oxin-type compounds containing oxine (commonly known as 8-quinolinol or 8-hydroxyquinoline chelate, such as tris(8-hydroxyquinoline) aluminum, tris(5 , 7-dichloro-8-hydroxyquinoline)aluminum, tris(5,7-dibromo-8-hydroxyquinoline)aluminum, tris(2-methyl-8-hydroxyquinoline)aluminum, etc. Also listed Replace the central metal of these metal complexes with metal complexes of indium, magnesium, copper, calcium, tin or lead, etc. Metal-free or metal phthalocyanines or their ends are substituted by alkyl groups, sulfone groups, etc. of.

The hole-transporting material may be any material as long as it has the above properties, and for example, the following materials can be used.

Distyrylbenzene derivatives, distyrylamine derivatives, triarylamine derivatives, azomethine derivatives, distyrylarylene derivatives, oxadiazole derivatives, bicarbazole derivatives, Oligothiophene derivatives, tetraphenylbutadiene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, and the like.

Preferably, distyrylarylene derivatives, stilbene derivatives, carbazole derivatives, and triarylamine derivatives are used, and N, N'-bis(4'-diphenylamino-4-biphenyl) is more preferably used -N,N'-Diphenylbenzidine.

For the same reason as above, a material that does not emit light when forming the non-emitting layer 13 can be appropriately selected from the materials exemplified above.

At least one of the electron transporting materials may be the same material as at least one of the materials contained in the electron injection transport layer 14/the materials usable in the electron injection transport layer 14 . That is, the electron transport material contained in the electron injection transport layer 14 can be used as the electron transport material.

Such a configuration can prolong device life (reduce deterioration of non-emitting layer 14/deterioration of electron-transporting material in non-emitting layer 14) because non-emitting layer 14 contains a hole-transporting material. That is, the hole-transporting material is resistant to holes and excitons. Therefore, even if the electron-transporting material contained in the electron-injection-transporting layer 14 is contained in the non-luminescent layer 14, a layer composed of only the electron-transporting material In comparison, the degradation of the layer can also be reduced.

At least one of the hole-transporting materials may be the same material as at least one of the materials contained in the light-emitting layer 12/materials that can be used in the light-emitting layer 12, but in order not to emit light in the non-light-emitting layer 13, for example This can be done as follows.

- As will be described later, the light-emitting layer 12 is composed of a host material and a dopant, and the above-mentioned host material is used as a hole-transporting material of the non-light-emitting layer 13 .

In this case, there is no luminescence of the host material itself (no luminescence peak is seen).

- A material used to form the light-emitting layer 12 but not contained in the light-emitting layer 12 is used, and when contained in the non-light-emitting layer 13, it does not emit light (no emission peak is seen).

<Manufacturing method>

The non-emitting layer 13 can be formed by forming a film on the light-emitting layer 12 using a known film-forming method for forming each layer of an organic EL element such as a sputtering method or an ion plating method, a vacuum evaporation method, a spin coating method, and an electron beam evaporation method. made from the above materials. For example, using tris(8-quinolinol)aluminum as an electron-transporting material and bis(2-methyl-8-quinolinol)(p-phenylphenolate)aluminum as a hole-transporting material, by 12 by co-evaporation to form a non-emitting layer 13 . The non-light-emitting layer 13 formed in this way has the effects of the above-mentioned non-light-emitting layer 13 (long lifetime, etc.). In addition, luminescence from the non-luminescent layer 13 (ie, luminescence peaks derived from tris(8-quinolinolato)aluminum or the like) was not observed.

The film thickness of the non-emitting layer 13 varies depending on the material used, but is usually about 0.5 nm to 50 nm.

As described above, if the non-emitting layer 13 is provided between the light-emitting layer 12 and the electron injection transport layer 14 of the organic EL element, the device life can be extended more than the conventional organic EL element without the non-emitting layer 13 .

When the organic EL element provided with the non-emitting layer 13 was produced, it was found that the magnitude of the current flowing through the organic EL element, that is, the chromaticity change due to the luminance was smaller than that of the conventional organic EL element without the non-emitting layer 13 .

Hereinafter, layers other than the non-emitting layer will be described.

"Anode 10"

The anode 10 is an electrode for injecting holes into the hole injection transport layer 11 . Therefore, the material used to form the anode 10 is only required to provide the anode 10 with such properties, and generally known materials such as metals, alloys, electrically conductive compounds, and mixtures thereof can be selected.

Materials used to form the anode 10 include, for example, the following materials.

ITO (indium-tin oxide), IZO (indium-zinc oxide), tin oxide, zinc oxide, zinc aluminum oxide, titanium nitride and other metal oxides or metal nitrides;

Gold, platinum, silver, copper, aluminum, nickel, cobalt, lead, chromium, molybdenum, tungsten, tantalum, niobium and other metals;

Alloys of these metals or copper iodide alloys, etc.,

Conductive polymers such as polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, poly(3-methylthiophene), polyphenylene sulfide, etc.

When the anode 10 is provided on the light extraction side rather than the light emitting layer 12, the transmittance of the extracted light is generally set to be greater than 10%. When extracting light in the visible light region, it is preferable to use ITO having a high transmittance in the visible light region.

When used as a reflective electrode, a material capable of reflecting extracted light to the outside can be appropriately selected from among the above-mentioned materials, and usually a metal, an alloy, or a metal compound is selected.

The anode 10 may be formed of only one of the above-mentioned materials, or may be formed by mixing a plurality of them. A multilayer structure including multiple layers of the same composition or different compositions is also possible.

When the resistance of the anode 10 is high, an auxiliary electrode can be provided to reduce the resistance. The auxiliary electrode is an electrode in which metal such as copper, chromium, aluminum, titanium, aluminum alloy or a laminate thereof is provided in parallel with the anode 10 .

The anode 10 is formed using the above-mentioned materials by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum deposition method, a spin coating method, or an electron beam deposition method.

Ozone washing, oxygen plasma washing or UV washing can also be performed to increase the work function of the surface. In order to suppress short circuits or defects in organic EL elements, the surface roughness can be controlled to 20nm or less in root mean square value by miniaturizing the particle size or polishing after film formation.

The film thickness of the anode 10 varies depending on the material used, usually about 5nm-1μm, preferably about 10nm-1μm, more preferably about 10-500nm, particularly preferably about 10nm-300nm, ideally selected within the range of 10-200nm .

The surface resistance of the anode 10 is preferably set to several hundred ohms/sheet or less, more preferably around 5-50 ohms/sheet.

"Hole Injection Transport Layer 11"

The hole injection transport layer 11 is a layer provided between the anode 10 and the light emitting layer 12 , injects holes from the anode 10 and transports the injected holes to the light emitting layer 12 . The ionization potential of the hole injection transport layer 11 is generally set to be between the work function of the anode 10 and the ionization potential of the light emitting layer 12, usually set at 5.0eV-5.5eV.

The organic EL element shown in FIG. 1 has the following properties because it includes the hole injection transport layer 11 .

・The driving voltage is low.

· Since the hole injection from the anode 10 to the light-emitting layer 12 is stable, the device life is long.

· Since the adhesion between the anode 10 and the light emitting layer 12 is improved, the uniformity of the light emitting surface can be improved.

·Protrusions of the anode 10 are covered to reduce device defects.

When the hole injection transport layer 11 is provided on the light extraction side rather than the light emitting layer 12, it is formed to be transparent to the extracted light. A material that is transparent to the above-mentioned light when formed into a thin film is appropriately selected from materials that may form the hole injection transport layer 11, and the transmittance of extracted light is usually set to be greater than 10%.

The material for forming the hole injection transport layer 11 is not particularly limited as long as the hole injection transport layer 11 has the above properties, and a known material that can be used as a hole injection material that can be used as a photoconductive material can be used. material, or known materials used for the hole injection transport layer of the organic EL element, etc., are selected and used.

For example, phthalocyanine derivatives or triazole derivatives, triarylmethane derivatives, triarylamine derivatives, oxazole derivatives, oxadiazole derivatives, hydrazone derivatives, stilbene derivatives, pyrazoline derivatives, Azolinone derivatives, polysilane derivatives, imidazole derivatives, phenylenediamine derivatives, amino-substituted chalcone derivatives, styryl anthracene derivatives, fluorene derivatives, hydrazone derivatives, silazane derivatives, Aniline copolymers, porphyrin derivatives, polyaryl alkane derivatives, polyphenylene vinylene and its derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole derivatives, etc., thiophene Conductive polymer oligomers such as oligomers, aromatic tertiary amine compounds, styrylamine compounds, etc.

Triarylamine derivatives are: 4,4'-bis[N-phenyl-N-(4"-methylphenyl)amino]biphenyl, 4,4'-bis[N-phenyl-N-(3 "-Methylphenyl)amino]biphenyl, 4,4'-bis[N-phenyl-N-(3"-methoxyphenyl)amino]biphenyl, 4,4'-bis[N- Phenyl-N-(1”-naphthyl)amino]biphenyl, 3,3’-dimethyl-4,4’-bis[N-phenyl-N-(3”-methylphenyl)amino ]biphenyl, 1,1-bis[4'-[N,N-bis(4"-methylphenyl)amino]phenyl]cyclohexane, 9,10-bis[N-(4'-methyl phenyl)-N-(4”-n-butylphenyl)amino]phenanthrene, 3,8-bis(N,N-diphenylamino)-6-phenylphenanthridine, 4-methyl-N , N-bis[4", 4-bis[N', N"-bis(4-methylphenyl)amino]biphenyl-4-yl]aniline, N,N"-bis[4-(two Phenylamino)phenyl]-N,N'-diphenyl-1,3-diaminobenzene, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-di Phenyl-1,4-diaminobenzene, 5,5"-bis[4-(bis[4-methylphenyl]amino)phenyl]-2,2': 5',2"-タ-リフェン, 1,3,5-tris(diphenylamino)benzene, 4,4',4"-tris(N-carbazolyl)triphenylamine, 4,4',4"-tris[N-( 3-methylphenyl)-N-phenylamino]triphenylamine, 4,4',4"-tri[N,N-bis(4-tert-butylbiphenyl-4""-yl )amino]triphenylamine, 1,3,5-tris[N-(4'-diphenylaminophenyl)-N-phenylamino]benzene, trimer of triphenylamine, N,N '-bis(4'-diphenylamino-4-biphenyl)-N,N'-diphenylbenzidine, etc.

Porphyrin compounds are, for example: porphyrin, 1,10,15,20-tetraphenyl-21H,23H-porphine copper (II), 1,10,15,20-tetraphenyl-21H,23H-porphine Zinc(II), 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphine, silicon phthalocyanine oxide, aluminum phthalocyanine chloride, phthalocyanine (metal-free), dilithium phthalocyanine Cyanine, copper tetramethylphthalocyanine, copper phthalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, copper octamethylphthalocyanine, etc.

Examples of aromatic tertiary amine compounds and styrylamine compounds are: N,N,N',N'-tetraphenyl-4,4'-diaminophenyl, N,N'-diphenyl-N, N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine, 2,2-bis(4-di-p-tolylaminophenyl)propane, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N,N',N'-tetra-p-tolyl-4,4'-diaminophenyl, 1,1-bis (4-Di-p-tolylaminophenyl)-4-phenylcyclohexane, bis(4-dimethylamino-2-methylphenyl)phenylmethane, bis(4-di-p-tolylaminobenzene base) phenylmethane, N, N'-diphenyl-N, N'-bis(4-methoxyphenyl)-4,4'-diaminobiphenyl, N, N, N', N' -Tetraphenyl-4,4'-diaminophenyl ether, 4,4'-bis(diphenylamino)quaterphenyl, N,N,N-tris(p-tolyl)amine, 4-(diphenylamino) p-tolylamino)-4'-[4-(di-p-tolylamino)styryl]stilbene, 4-N,N-diphenylamino-2-diphenylvinylbenzene, 3-methoxy -4'-N, N-diphenylamino stilbenzen, N-phenylcarbazole, etc. In addition, an aromatic dimethyl compound can also be used as a material of the hole injection transport layer 310 .

The hole injection transport layer 11 may be formed of one of the above-mentioned materials, or may be formed by mixing a plurality of materials. In addition, a multilayer structure including multiple layers of the same composition or a plurality of compositions may also be used.

The hole injection transport layer 11 can be formed on the anode by a known thin film forming method such as a vacuum evaporation method, a spin coating method, a tape casting method, or an LB method.

The film thickness varies according to the selected material, and is usually 5nm-5μm.

"Glow Layer 12"

The light-emitting layer 12 is mainly composed of organic materials. Holes and electrons are respectively injected from the side of the anode 10 and the side of the cathode 15, at least one of the holes and electrons is transported, and the two recombine to form excitons. When the excitons return to the ground state, A layer that emits electroluminescence (light).

Therefore, the material (organic material) used to form the light emitting layer 12 may have the following functions.

- A transport function of moving at least one of injected holes and electrons by an electric field force.

・The function of recombining electrons and holes to generate an excited state (exciton).

·The function of generating electroluminescence when the excited state returns to the ground state.

Representative examples of materials having the above functions include tris(8-quinolinol)aluminum or Be-benzoquinolinol.

The following materials can also be used.

2,5-bis(5,7-di-tert-pentyl-2-benzoxazolyl)-1,3,4-thiadiazole, 4,4'-bis(5,7-pentyl-2- Benzoxazolyl)stilbene, 4,4'-bis[5,7-bis-(2-methyl-2-butyl)-2-benzoxazolyl]stilbene, 2,5-bis(5 , 7-di-tert-amyl-2-benzoxazolyl)-thiophene, 2,5-bis([5-α,α-dimethylbenzyl]-2-benzoxazolyl)thiophene, 2 , 5-bis[5,7-bis-(2-methyl-2-butyl)-2-benzoxazolyl]-3,4-diphenylthiophene, 2,5-bis(5-methyl Base-2-benzoxazolyl)thiophene, 4,4'-bis(2-benzoxazolyl)biphenyl, 5-methyl-2-[2-[4-(5-methyl-2 -Benzoxazolyl)phenyl]vinyl]benzoxazolyl, 2-[2-(4-chlorophenyl)vinyl]naphtho[1,2-d]oxazole and other benzoxazoles System, 2,2'-(p-phenylene divinylene)-dibenzothiazole and other benzothiazole series, 2-[2-[4-(2-Benzimidazolyl)phenyl]vinyl] Benzimidazole, 2-[2-(4-carboxyphenyl)vinyl]benzimidazole and other benzimidazole-based fluorescent whitening agents;

Bis(8-quinolinol) magnesium, bis(benzo-8-quinolinol) zinc, bis(2-methyl-8-quinolinol) aluminum oxide, tris(8-quinolinol) indium, Tris(5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris(5-chloro-8-quinolinol) gallium, bis(5-chloro-8-quinolinol) calcium, poly [Zinc-bis(8-hydroxy-5-kinolinonil)methane] and other 8-hydroxyquinoline metal complexes, metal chelated okinoid compounds such as dilithium epindrizion, 1,4-bis(2-methylstyrene Base) benzene, 1,4-(3-methylstyryl)benzene, 1,4-bis(4-methylstyryl)benzene, distyrylbenzene, 1,4-bis(2-ethyl Styrylbenzene compounds such as 1,4-bis(3-ethylstyryl)benzene, 1,4-bis(2-methylstyryl)2-methylbenzene, 2,5-bis(4-methylstyryl)pyrazine, 2,5-bis(4-ethylstyryl)pyrazine, 2,5-bis[2-(1-naphthyl)vinyl ]pyrazine, 2,5-bis(4-methoxystyryl)pyrazine, 2,5-bis[2-(4-biphenyl)vinyl]pyrazine, 2,5-bis[2- (1-pyrenyl)vinyl]pyrazine and other jistyl pyrazine derivatives, naphthalimide derivatives, perylene derivatives, oxadiazole derivatives, aldehyde azine derivatives, cyclopentadiene derivatives, Styrylamine derivatives, coumarin derivatives, aromatic dimethyl derivatives, anthracene, salicylate, pyrene, coronene or tris(2-phenylpyridine)iridium and other phosphorescent materials.

The light-emitting layer 12 may contain a material (organic light-emitting material/dopant) that performs the function of generating electroluminescence, and a material that performs other functions (host material). In this case, the host material injects and transports carriers, and becomes an excited state by recombination. The host material in the excited state transfers the excitation energy to the dopant. Alternatively, a mechanism in which the host material transports carriers to the dopant, recombines in the dopant, and the dopant emits light when it returns to the ground state may also be employed. The dopant produces electroluminescence when it returns to the ground state. As a dopant, generally, a fluorescent material or a phosphorescent material can be used.

As the host material, any known material can be used as long as it has the above-mentioned functions. Examples include: distyryl arylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinoline alcoholate metal complexes, triarylamine derivatives, azomethine derivatives compounds, oxadiazole derivatives, pyrazoloquinoline derivatives, silacyclopentadiene derivatives, naphthalene derivatives, anthracene derivatives, bicarbazole derivatives, perylene derivatives, oligothiophene derivatives, four Phenylbutadiene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives.

A fluorescent material is a fluorescent material (a fluorescent dye, a fluorescent dopant), which absorbs energy from a host material and emits light when it transitions to a ground state. Usually, if a material with high fluorescence quantum efficiency is selected, the added amount is 0.01% by weight to 20% by weight relative to the host material.

Fluorescent materials can be appropriately selected from known materials having the above properties, for example: europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, Nile red, hydrogen -1,1,7,7-tetramethyl-1H,5H-benzo(i,j)quinazin-9-yl)-vinyl)-4H-pyran-4H-ylidene)malononitrile, 4-(dicyanomethylene)-2-(methyl)-6-(p-dimethyl-amino-styryl)-4H-pyran, coumarin derivatives, quinacridone derivatives , distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives,  derivatives, phenanthrene derivatives, diphenyl Vinylbenzene derivatives, tetraphenylbutadiene, rubrene, etc.

Phosphorescent material is a phosphorescent material (phosphorescent pigment, phosphorescent dopant), which absorbs energy from a host material, emits light when it transitions to a ground state, and can obtain light emission from a singlet state or a triplet state of an excited state at room temperature. The addition amount (doping amount) of the phosphorescent material is usually 0.01% by weight to 30% by weight relative to the host material.

The phosphorescent material is not particularly limited as long as it can utilize singlet and triplet light emission from an excited state at room temperature, and known materials selected as phosphorescent materials for the light emitting layer can be used. Usually, phosphorescent heavy metal complexes are often used.

For example, tris(2-phenylpyridine)iridium can be used as a green phosphorescent material. As the red phosphorescent material, 2,3,7,8,12,13,17,18-octaethyl-21H23H-porphine platinum(II) can be used. It is also possible to change the central metal of these materials to other metals.

The light-emitting layer 12 can be provided on the hole injection transport layer 11 by, for example, a known thinning method such as vacuum evaporation, spin coating, tape casting, and LB method.

The film thickness varies depending on the material used, but is usually about 1 nm to 100 nm, preferably about 2 to 50 nm.

It is also possible to add a variety of dopants in the same layer to make the luminous color mix, or to emit two or more lights, or to transfer the energy from the host material to the low-energy first dopant, and then transfer the energy to a lower energy level. The low-energy second dopant is transferred efficiently. A mechanism may also be employed in which the host material transports the carriers to the dopant, recombines within the dopant, and generates light when the dopant returns to the ground state.

The chromaticity, purity, lightness, brightness, etc. of the light (electroluminescence) emitted from the light-emitting layer 12 are adjusted by selecting the type of material forming the light-emitting layer 12 , adjusting the amount of addition, adjusting the film thickness, and the like.

The method of adjusting the luminescent color of the luminescent layer 12 includes the following methods. Emission color can be adjusted using one or more of these methods.

-A method of adjusting by providing a color filter on the light extraction side closer to the light emitting layer 12 .

Color filters adjust the emission color by limiting the transmitted wavelengths. For the color filter, known materials such as cobalt oxide as a blue filter, a mixed system of cobalt oxide and chromium oxide as a green filter, and iron oxide as a red filter can be used. and other known thin film forming methods are formed on the substrate 2 .

・A method of adjusting the color of luminescence by adding a material that promotes or inhibits luminescence.

For example, the energy received from the host material is transferred to the dopant, and the energy can be easily transferred from the host material to the dopant by adding a so-called co-dopant. As the auxiliary dopant, known materials can be appropriately selected, for example, selected from the above-mentioned materials that can be used as host materials or dopants.

- A method in which a wavelength converting material is added to a layer (including the substrate 2 ) on the light-extraction side of the light-emitting layer 12 to adjust the emission color.

Known wavelength conversion materials can be used as the material, for example, a fluorescence conversion substance that converts light emitted from the light-emitting layer 12 into light of other low-energy wavelengths can be used. The type of fluorescent conversion substance can be appropriately selected according to the wavelength of light to be emitted from the target organic EL element and the wavelength of light to be emitted from the light-emitting layer 12 . In addition, the amount of the fluorescent conversion substance used can be appropriately selected according to the type within the range where concentration extinction does not occur, and is about 10 ^-5 -10 ^-4 mol/L relative to the transparent resin (uncured). A single type of fluorescence conversion substance may be used, or a combination of multiple types may be used. When multiple types are used in combination, white light or intermediate-color light can be emitted in addition to blue, green, and red light, depending on the combination. Specific examples of fluorescence conversion substances include those shown in (a) to (c) below.

(a) A substance that is excited by ultraviolet light and emits blue light

1,4-bis(2-methylstilin)benzene, stilbene-based dyes such as trans-4,4'-diphenylstilbene, coumarin-based dyes such as 7-hydroxy-4-methylcoumarin, 4 , 4'-bis(2,2'-diphenylvinyl)biphenyl and other pigments.

(b) A substance that is excited by blue light and emits green light

2,3,5,6-1H,4H-tetrahydro-8-trifluoromethylquinazino(9,9a,1-gh)coumarin and other coumarin pigments, etc.

(c) Substances that are excited by light of blue to green wavelengths and emit light of orange to red wavelengths

4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran, 4-(dicyanomethylene)-2-phenyl- 6-(2-(9-julolidinyl)vinyl)-4H-pyran, 4-(dicyanomethylene)-2,6-bis(2-(9-julolidinyl)ethene base)-4H-pyran, 4-(dicyanomethylene)-2-methyl-6-(2-(9-julolidinyl)vinyl)-4H-pyran, 4-(di Cyanine pigments such as cyanomethylene)-2-methyl-6-(2-(9-julolidinyl)vinyl)-4H-thiopyran, 1-ethyl-2-(4-( Pyridine-based pigments such as p-dimethylaminophenyl)-1,3-butadienyl)-pyridine-Pa-Colareit (pyridine 1), xanthine-based pigments such as Rhodamine B and Rhodamine 6G, and oxazine-based pigments wait.

The above-described effect can be obtained particularly when the light-emitting layer 12 is hole-transporting.

Since the light-emitting layer 12 is hole transporting, the number of holes entering the electron injection transport layer 13 without recombining with electrons increases. Therefore, by providing the non-emitting layer 13 on such an organic EL element, the lifetime of the element can be greatly extended.

"Electron Injection Transport Layer 14"

The electron injection transport layer 14 is a layer provided between the cathode 15 and the non-emitting layer 13, and is a layer for transporting electrons injected from the cathode 15 to the non-emitting layer 13, and imparts the above-mentioned properties to the organic EL element.

The material used to form the electron injection transport layer 14 is selected from known materials that can be used as the electron injection material of the photoconductive material, or known materials used in the electron injection transport layer of the organic EL device. A material whose electron affinity is between the work function of the cathode and the electron affinity of the non-emitting layer 13 .

Specifically, 1,3-bis[5'-(p-tert-butylphenyl)-1,3,4-oxadiazol-2'-yl]benzene, 2-(4-biphenyl)-5- (4-tert-butylphenyl)-1,3,4-oxadiazole and other oxadiazole derivatives; 3-(4'-tert-butylphenyl)-4-phenyl-5-(4”- Triazole derivatives such as biphenyl)-1,2,4-triazole, etc. Triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitric acid derivatives, etc. Substituted fluorenone derivatives, tetraphenylmethane derivatives, thiopyran derivatives, anthraquinone dimethane derivatives, thiopyran derivatives, heterocyclic tetracarboxylic anhydrides such as naphthalene perylene, carbodiimide, imide Fluorenylmethane derivatives, anthraquinone dimethane derivatives, anthrone derivatives, distyrylpyrazine derivatives, phenanthroline derivatives, and the like.

Can also suitably select organometallic complexes such as bis(10-benzo[h] quinolinol) beryllium, the beryllium salt of 5-hydroxyflavone, the aluminum salt of 5-hydroxyflavone, particularly preferably select 8-hydroxyquinoline or Metal complexes of its derivatives. Specific examples are: metal-chelated oxin-type compounds containing oxine (usually a chelate of 8-quinolinol or 8-hydroxyquinoline, such as tris(8-quinolinol)aluminum, tris(5, 7-dichloro-8-quinolinol)aluminum, tris(5,7-dibromo-8-quinolinol)aluminum, tris(2-methyl-8-quinolinol)aluminum, etc. There are also these The central metal of the metal complex is substituted with a metal complex of indium, magnesium, copper, calcium, tin, or lead, etc. It is preferable to use metal-free or metal phthalocyanines or compounds whose terminals are substituted with alkyl groups, sulfone groups, or the like.

The electron injection transport layer 14 may be formed of only one of the above-mentioned materials, or may be formed by mixing two or more kinds of materials. A multilayer structure including multiple layers of the same composition or different compositions is also possible.

The electron injecting and transporting layer 14 is formed using the above-mentioned materials by a known film-forming method such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation.

The film thickness varies depending on the material used, but is usually 5nm-5μm.

When the electron injection transport layer 14 is provided on the side closer to the light extraction side than the light emitting layer 12, it must be transparent to the extracted light. Therefore, a material that is transparent to the light when formed into a thin film is appropriately selected from materials that can form the electron injection transport layer 14, and the transmittance of extracted light is usually set to be greater than 10%.

"Cathode 15"

The cathode 15 is an electrode for injecting electrons into the electron injection transport layer 14. In order to improve the electron injection efficiency, metals or alloys, electrically conductive compounds, and mixtures thereof with a work function lower than 4.5 eV are used as electrode materials.

Examples of the aforementioned electrode substances include lithium, sodium, magnesium, silver, copper, aluminum, indium, calcium, tin, ruthenium, titanium, manganese, chromium, yttrium, aluminum-calcium alloys, aluminum-lithium alloys, aluminum-magnesium alloys, Magnesium-silver alloy, magnesium-indium alloy, lithium-indium alloy, sodium-potassium alloy, sodium-potassium alloy, magnesium/copper mixture, aluminum/alumina mixture, etc. Materials usable as materials for anodes can also be used.

When the cathode 15 is located on the light-extracting side closer to the light-emitting layer 12, it is set to have a transmittance greater than 10% for the extracted light. For example, a transparent conductive oxide is laminated on an ultra-thin magnesium-indium alloy. And the formed electrode etc. In this cathode, a buffer layer containing copper phthalocyanine or the like may be provided between the cathode 15 and the electron injection transport layer 14 in order to prevent the organic light emitting layer 31 and the like from being damaged by plasma during sputtering of the conductive oxide.

When used as a light-reflective electrode, among the above-mentioned materials, a material capable of reflecting extracted light to the outside is appropriately selected, and usually a metal, an alloy, or a metal compound is selected.

The cathode 15 may be formed of the above-mentioned materials alone, or may be formed of a plurality of materials. For example, adding 1% to 20% of silver or copper to magnesium, or 0.1 to 10% by weight of lithium to aluminum can prevent the oxidation of the cathode 15, and the adhesion between the cathode 15 and the electron injection transport layer 14 is also improved. improve.

The cathode 15 may have a multilayer structure including layers of the same composition or different compositions. For example, the following structures can be used.

• In order to prevent the oxidation of the cathode 15, a protective layer containing a corrosion-resistant metal is provided on the portion of the cathode 15 that is not in contact with the electron injection transport layer 14.

As a material for forming the protective layer, for example, silver or aluminum is preferably used.

• In order to reduce the work function of the cathode 15, oxides or fluorides, metals, compounds, etc. with a small work function are inserted at the interface between the cathode 15 and the electron injection transport layer 14.

For example, the material of the cathode 15 is aluminum, and lithium fluoride or lithium oxide is inserted in the interface part.

The cathode 15 can be formed by known thin film forming methods such as vacuum evaporation, sputtering, ionization evaporation, ion plating, and electron beam evaporation.

The film thickness varies depending on the material of the electrode substance used, and is usually about 5 nm-1 μm, preferably about 5-1000 nm, particularly preferably about 10-500 nm, and most preferably set at 50-200 nm.

The surface resistance of the cathode 15 is preferably set to several hundred ohms/sheet or less.

"Other layers, additives"

Known layers other than those shown in FIG. 1 may be provided in the organic EL device of this embodiment, and known additives (dopants) or the like may be added (doped) to the formed layers. For example, the following modifications are possible.

<Layer set between layers>

A layer may be provided to improve the adhesion between layers, or to improve electron injection or hole injection.

For example, the material forming the cathode 15 and the material forming the electron injection transport layer 14 are co-evaporated to obtain a cathode interface layer, which is provided between the above two layers. Thereby, the energy barrier of electron injection existing between the light-emitting layer 12 and the cathode 15 can be eased. It is also possible to improve the adhesion between the cathode 15 and the electron injection transport layer 14 .

The material used to form the cathode interface layer is not particularly limited as long as the cathode interface layer has the above properties, and any material can be used, and known materials can also be used. For example, alkali metals such as lithium fluoride, lithium oxide, magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride, fluorides, oxides, chlorides, and sulfides of alkaline earth metals can be used. The cathode interface layer may be formed of a single material, or may be formed of multiple materials.

The film thickness is about 0.1nm-10nm, preferably 0.3nm-3nm.

The cathode interface layer may be formed in a uniform thickness within the cathode interface layer, or may be formed unevenly, may be formed in an island shape, and may be formed by a known thin film forming method such as vacuum evaporation.

<protection layer>

In order to prevent the organic EL element from contact with oxygen or moisture, a protective layer (encapsulating layer, surface stabilizing film) may be provided.

Materials used for the protective layer include, for example, organic polymer materials, inorganic materials, and photocurable resins, etc. The materials used for the protective layer can be used alone or in combination. The protective layer can be a single-layer structure or a multi-layer structure.

Examples of organic polymer materials include fluororesins such as chlorotrifluoroethylene polymers, dichlorodifluoroethylene polymers, copolymers of chlorotrifluoroethylene polymers and dichlorodifluoroethylene polymers, polymethacrylate Acrylic resins such as esters and polyacrylates, epoxy resins, silicone resins, epoxy silicone resins, polystyrene resins, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyamide imide Amine resin, parylene resin, polyethylene resin, polyphenylene ether resin, etc.

Inorganic materials include, for example, diamond thin films, amorphous silica, electrically insulating glass, metal oxides, metal nitrides, metal carbides, and metal sulfides.

The above-mentioned fluorescent conversion substance may be added to the above-mentioned materials.

The organic EL element can also be encapsulated in an inert substance such as paraffin, liquid paraffin, silicone oil, fluorocarbon oil, fluorocarbon oil added with zeolite, and the like for protection.

<Doping to Hole Injection Transport Layer 11 and Electron Injection Transport Layer 14 >

An organic light-emitting material (dopant) such as a fluorescent material or a phosphorescent material can be doped into the hole injection transport layer 11 or the electron injection transport layer 14 to make these layers also emit light.

<Doping Alkali Metal or Alkali Metal Compound into the Layer Adjacent to the Cathode 15 >

When metal such as aluminum is used for the cathode 15 , in order to relax the energy barrier between the cathode 15 and the organic light-emitting layer 31 , the layer adjacent to the cathode 15 may be doped with an alkali metal or an alkali metal compound. Since the organic layer is reduced by the added metal or metal compound to generate anions, the electron injectability is improved and the applied voltage is reduced. Examples of alkali metal compounds include oxides, fluorides, lithium chelates and the like.

"Substrate 2"

The substrate 2 is a main plate-like member supporting the organic EL element. Since the respective layers constituting an organic EL element are very thin, it is usually made in the form of an organic EL device supported by a substrate 2 .

Since the substrate 2 is a member of the organic EL element of the laminate 3, it is preferable to have planar smoothness.

When the substrate 2 is provided on the side closer to the light extraction side than the light emitting layer 12, it is transparent to the extracted light.

As the substrate 2, known ones can be used as long as they have the above properties. Ceramic substrates such as glass substrates, silicon substrates, and quartz substrates or plastic substrates are usually selected. A metal substrate or a substrate on which a metal foil is formed on a support may also be used. A substrate composed of a composite sheet obtained by combining a plurality of substrates of the same type or different types can be used.

In this way, the organic EL element of this embodiment may have any one of the following configurations (1) to (8), and other parts may be appropriately modified.

(1) A light-emitting layer, an electron injection transport layer, and a cathode are arranged in sequence at least on the anode, and a non-light-emitting layer is arranged between the electron injection transport layer and the light-emitting layer, wherein the hole transport property of the non-light-emitting layer is higher than that of the above-mentioned electron injection transport layer large and possess electron transport properties.

(2) In the configuration of (1) above, the non-emitting layer has a higher electron-transport property than a hole-transport property.

(3) In the configuration of (1) or (2) above, the non-emitting layer contains a material having a higher hole-transport property than the electron injection transport layer and having electron-transport properties.

(4) In the composition of (1) or (2) above, the non-emitting layer contains one or more electron transporting materials with electron transport properties, one or more materials with higher hole transport properties than the electron injection transport layer. The composition of the positive hole transport material.

(5) In the configuration of (4) above, at least one of the electron transport materials is the same material as at least one of the materials contained in the electron injection transport layer.

(6) In the configuration of (4) or (5) above, at least one of the hole-transporting materials is the same material as at least one of the materials contained in the light-emitting layer.

(7) In the configuration of any one of (4) to (6) above, a configuration in which the electron-transporting property of the electron-transporting material is higher than the hole-transporting property of the hole-transporting material.

(8) In the configuration of any one of the above (1) to (7), the light-emitting layer has a high electron-transport property and a high hole-transport property.

"Other Examples"

Therefore, for example, as shown in FIG. 2, a plurality of layers made of the same or different materials using the above-mentioned materials may be laminated to form a non-emitting layer. In Fig. 2, the composition of anode 40, hole injection transport layer 41, luminescent layer 42, first non-luminescent layer 430, second non-luminescent layer 431, electron injection transport layer 44 and cathode 45 are sequentially stacked on substrate 3 . In this configuration, the layers other than the first non-emitting layer 430 and the second non-emitting layer 431 are respectively equivalent to the respective layers in the first embodiment described above.

As described above, when the non-light emitting layer is composed of multiple layers, the above effect can be obtained if the non-light emitting layers 430 and 431 are formed in the same manner as the non-light emitting layer in the above-mentioned first embodiment.

It can be seen that the second non-luminous layer 431 is made of a single material such as tris(8-quinolinol)aluminum, and the material forming the second non-luminous layer 431 (tris(8-quinolinol)aluminum in this example) is used as The electron-transporting material of the first non-emitting layer 430 adopts the same material as the holes in the light-emitting layer 42 as the hole-transporting material of the first non-emitting layer 430, and the organic EL element thus formed has a long device life. , high luminous efficiency. That is, it can be seen that a good electron transport property can be obtained by sequentially decreasing the hole transport property from the light emitting layer 42 to the electron injection transport layer 44, or by increasing the electron transport property sequentially from the light emitting layer 42 to the electron injection transport layer 44. Effect.

It is considered that the energy gap between the layers from the light emitting layer 42 to the electron injection transport layer 44 is smaller than the energy gap between the layers of the conventional device, which also affects the above effect.

As shown in FIG. 3 or FIG. 4 , the light-emitting layer may be composed of multiple layers, and the peak of light emitted from one layer may be different from the peak of light emitted from at least another layer.

In the structure shown in FIG. 3 , an anode 60 , a hole injection transport layer 61 , a blue light emitting layer 620 , a red and green light emitting layer 621 , a non-light emitting layer 63 , and an electron injection transport layer 64 are sequentially laminated on a substrate 5 . With the configuration of the cathode 65, red, green, and blue lights are emitted to express white. In this configuration, the layers other than the red and green light-emitting layers 621 and the blue light-emitting layer 620 can be configured in the same manner as the respective layers in the organic EL element shown in FIG. 1 .

The blue light-emitting layer 620 is preferably formed by mixing a blue light-emitting dopant with a host material, for example, by co-evaporation or the like, and formed on the side closer to the cathode 65 than the red and green light-emitting layers 620 .

The dopant whose luminescent color is blue can suitably use known dopants for blue luminescence, for example: distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives Compounds, benzothiazole derivatives, benzimidazole derivatives,  derivatives, phenanthrene derivatives, distyrylbenzene derivatives, tetraphenylbutadiene, etc.

The host material for the blue light-emitting layer 621 can be suitably a known host material used in the light-emitting layer of an organic EL element having a blue dopant, for example: distyryl arylene derivatives, stilbene Derivatives, carbazole derivatives, triarylamine derivatives, bis(2-methyl-8-quinolinol)(p-phenylphenol)aluminum, etc.

The red and green light-emitting layers 621 are preferably formed by co-evaporating or mixing a red dopant and a green dopant with a host material.

The red dopant and the green dopant can be appropriately selected from known dopants. Dopants whose luminescent color is red include, for example, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, Nile red, 2-(1,1- Dimethylethyl)-6-(2-(2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H-benzo(ij)quinolazine-9- Base) vinyl) -4H-pyran-4H-ylidene) malononitrile, 4-(dicyanomethylene)-2-(methyl)-6-(p-dimethyl-amino-styrene base)-4H-pyran etc. Dopants whose emission color is green include, for example, coumarin derivatives, distyrylamine derivatives, quinacridone derivatives, and the like.

The host material used in the red and green light-emitting layers 621 can suitably be a known host material used in the light-emitting layer of an organic EL element having a red or green dopant, for example: distyryl arylene Derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolate metal complexes, triarylamine derivatives, oxadiazole derivatives, silacyclopentadiene derivatives, Bicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, and the like. It is particularly preferred to use tris(8-quinolinolate)aluminum, N,N'-bis(4'-diphenylamino-4-biphenyl)-N,N'-diphenylbenzidine, 4,4' - bis(2,2'-diphenylvinyl)biphenyl.

In the structure shown in FIG. 4 , an anode 80 , a hole injection transport layer 81 , a blue luminescent layer 820 , a red luminescent layer 821 , a green luminescent layer 822 , a non-luminescent layer 83 , and an electron injection layer are sequentially laminated on a substrate 7 . The configuration of the transport layer 84 and the cathode 85 expresses white by emitting red, green, and blue light. In this configuration, the layers other than the blue light emitting layer 820, the red light emitting layer 821, and the green light emitting layer 822 can be configured in the same manner as the respective layers in the organic EL element shown in FIG. 1 .

The blue light-emitting layer 820 , the red light-emitting layer 821 and the green light-emitting layer 822 can be formed by mixing the above-mentioned dopants of each light-emitting color with a host material suitable for the dopant.

As shown in Figure 3 or Figure 4, it can be seen that when the light-emitting layer is composed of multiple layers, and the non-light-emitting layer is composed of an electron-transporting material and a hole-transporting material, the hole-transporting material is used as the light-emitting layer in contact with the non-emitting layer. (The red and green light-emitting layers 621 in FIG. 3, the green light-emitting layer 822 in FIG. 4) can obtain good organic EL elements with long device life.

second embodiment

"Layer Composition"

In the organic electroluminescent element of the second embodiment, at least a red light emitting layer, a blue light emitting layer and a cathode are sequentially formed on the anode, and the red light emitting layer contains a green light emitting dopant.

5 is a diagram illustrating the formation of an anode 10, a hole injection layer 31, a hole transport layer 51, a red light-emitting layer 321, a blue light-emitting layer 320, an electron transport layer 54, an electron injection layer 34, and a cathode 15 in sequence on a substrate 2. A diagram of an organic electroluminescent device. Hereinafter, referring to FIG. 5 , the organic electroluminescent element according to the second embodiment will be specifically described.

"Substrate 2"

The substrate 2 is a main plate-like member supporting the organic electroluminescence element. Since the layers constituting the organic electroluminescent element are very thin, it is usually produced in the form of an organic electroluminescent element supported by a substrate 2 .

The substrate 2 is a member of the stack 3 organic electroluminescence element, and therefore preferably has planar smoothness.

When the substrate 2 is provided on the light extraction side, it is transparent to the extracted light.

As the substrate 2, known ones can be used as long as they have the above properties. Ceramic substrates such as glass substrates, silicon substrates, and quartz substrates or plastic substrates are usually selected. A metal substrate or a substrate on which a metal foil is formed on a support may also be used. A substrate composed of a composite sheet obtained by combining a plurality of substrates of the same type or different types can be used.

"Anode 10"

The anode 10 is an electrode for injecting holes into the hole injection transport layer 11 . Therefore, the material used to form the anode 10 is only required to provide the anode 10 with such properties, and generally known materials such as metals, alloys, electrically conductive compounds, and mixtures thereof can be selected.

Materials used to form the anode 10 include, for example, the following materials.

ITO (indium-tin oxide), IZO (indium-zinc oxide), tin oxide, zinc oxide, zinc aluminum oxide, titanium nitride and other metal oxides or metal nitrides;

Gold, platinum, silver, copper, aluminum, nickel, cobalt, lead, chromium, molybdenum, tungsten, tantalum, niobium and other metals;

Alloys of these metals or copper iodide alloys, etc.,

Conductive polymers such as polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, poly(3-methylthiophene), polyphenylene sulfide, etc.

When the anode 10 is provided on the side closer to the light extraction side than the light emitting layer 12, the transmittance of the extracted light is generally set to be greater than 10%. When taking out light in the visible light region, it is preferable to use ITO having a high transmittance in the visible light region.

When used as a reflective electrode, a material capable of reflecting captured light to the outside can be appropriately selected from among the above-mentioned materials, and usually a metal, an alloy, or a metal compound is selected.

The anode 10 may be formed of only one of the above-mentioned materials, or may be formed by mixing a plurality of them. A multilayer structure including multiple layers of the same composition or different compositions is also possible.

When the resistance of the anode 10 is high, an auxiliary electrode can be provided to reduce the resistance. The auxiliary electrode is an electrode in which metals such as copper, chromium, aluminum, titanium, and aluminum alloys or laminates of these metals are provided in parallel with the anode 10 .

The anode 10 is formed on the substrate 2 by using the above-mentioned materials and by a known thin film forming method such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation.

Ozone cleaning, oxygen plasma cleaning, and UV cleaning can also be performed to increase the work function of the surface. In order to suppress short circuits or defects in organic EL elements, the root mean square value of the surface roughness can be controlled to 20nm or less by miniaturizing the particle size or polishing after film formation.

The film thickness of the anode 10 varies depending on the material used, and is usually about 5nm-1μm, preferably about 10nm-1μm, more preferably about 10-500nm, particularly preferably about 10nm-300nm, and preferably selected within the range of 10-200nm.

The surface resistance of the anode 10 is preferably set to several hundred ohms/sheet or less, more preferably around 5-50 ohms/sheet.

"Hole Injection Layer 31"

The hole injection layer 31 is provided between the anode 10 and the hole transport layer 51 . The hole injection layer 31 is a layer that transports holes injected from the anode 10 to the hole transport layer 51 . The film thickness of the hole injection layer 31 is preferably 0.5 nm to 200 nm, more preferably 7 nm to 150 nm. The reason why the film thickness in such a range is preferable is that the driving voltage is low and the protrusion of the cathode can be covered.

The material that can be used in the hole injection layer 31 is not particularly limited as long as the hole injection layer 31 has the above properties, and it can be selected from known materials or organic materials that can be used as hole injection materials that can be used as photoconductive materials. Any material selected from known materials used for the hole injection layer of the EL element is used. For example, there are triarylamines, arylenediamine derivatives, phenylenediamine derivatives, styryl compounds, 2,2-diphenylvinyl compounds, porphyrin derivatives, etc., among which p-phenylenediamine derivatives are preferred. substances, 4,4'-diaminobiphenyl derivatives, 4,4'-diaminodiphenylsulfane derivatives, 4,4'-diaminodiphenylmethane derivatives, 4,4-diaminobis Phenyl ether derivatives, 4,4'-diaminotetraphenylmethane derivatives, 4,4'-diaminostilbene derivatives, 1,1-diarylcyclohexanes, 4,4"-diamino Terphenyl derivatives, 5,10-bis-(4-aminophenyl)anthracene derivatives, 2,5-diarylpyridines, 2,5-diarylfurans, 2,5-diarylthiophenes Classes, 2,5-diarylpyrroles, 2,5-diaryl-1,3,4-oxadiazoles, 4-(diarylamino)stilbenes, 4,4'-bis(di Arylamino)stilbenes, N,N-diaryl-4-(2,2-diphenylvinyl)anilines, 1,4-bis(4-aminophenyl)naphthalene derivatives, 2,8 -bis(diarylamino)-5-thioxanthenes, 1,3-bis(diarylamino)isoindoles, etc. More preferably tris[4-[N-(3-methylphenyl)- N-phenylamino]phenyl]amine, tris[4-[N-(2-naphthyl)-N-phenylamino]phenyl]amine, porphyrin-copper complex, etc.

The hole injection layer 31 can be formed by forming a film of these materials on the anode 10 using known film forming methods such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation.

"Hole Transport Layer 51"

The hole transport layer 51 is disposed between the hole injection layer 31 and the red light emitting layer 321 . The hole transport layer 51 is a layer that transports the holes transported by the hole injection layer 31 to the red light emitting layer 321 .

The film thickness of the hole transport layer 51 is preferably 0.5 nm to 1000 nm, more preferably 10 nm to 800 nm.

The material that can be used for the hole transport layer 51 is as long as it is a material with high hole transport performance, for example: triamines, tetramines, benzidines, triarylamines, aromatic diamine derivatives, phenylenediamine Derivatives, p-phenylenediamine derivatives, m-phenylenediamine derivatives, 1,1-bis(4-diarylaminophenyl)cyclohexanes, 4,4'-bis(diarylamino)bis Benzene, bis[4-(diarylamino)phenyl]methane, 4,4"-bis(diarylamino)terphenyls, 4,4'-bis(diarylamino)quaterphenyls Classes, 4,4'-bis(diarylamino)diphenyl ethers, 4,4'-bis(diarylamino)diphenylsulfanes, bis[4-(diarylamino)phenyl ]dimethylmethanes, bis[4-(diarylamino)phenyl]-bis(trifluoromethyl)methanes, etc., among which aryl-bis(4-diarylaminophenyl)amines are preferred , 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, and the hole injection layer 31 are preferably exemplified materials.

The hole transport layer 51 can be formed by forming a film of these materials on the hole injection layer 31 using known film formation methods such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation.

"Red Luminous Layer 321"

The red light emitting layer 321 is disposed between the hole transport layer 51 and the blue light emitting layer 320 or the light emitting adjustment layer, and contains a green light emitting dopant. Therefore, in the red light-emitting dopant and the green light-emitting dopant of the red light-emitting layer 321, the holes and electrons respectively injected from the anode 10 and the cathode 15 recombine to become an excited state, and emit red light when returning to the ground state. and green light. The film thickness of the red light emitting layer 321 is preferably 0.5nm-50nm, more preferably 1nm-20nm.

The green light-emitting dopant contained in the red light-emitting layer 321 is not particularly limited as long as it is a dopant having green light-emitting properties, for example, coumarin derivatives, quinacridone derivatives, quinolinolates, etc. Metal complexes, distyrylamine derivatives, etc. Coumarin derivatives are particularly preferred due to their excellent green light-emitting function. Further preferred are 6-(alkyl or unsubstituted)-8-(alkyl or unsubstituted)-7-amino-3-aryl-4-(trifluoromethyl or unsubstituted)coumarin derivatives. Especially considering the conjugation of the aryl group at the 3-position of the coumarin core and the π electron of the coumarin core, preferably benzothiazol-2-yl, benzimidazol-2-yl, benzoxazole- 2-yl, benzoselenazol-2-yl and other groups, the benzene ring part in these aryl groups may be further substituted. The green light-emitting dopant is preferably contained in an amount of 0.1 to 15 parts by weight relative to 100 parts by weight of the hole-transporting host material. As long as it is within this range, excellent whiteness can be obtained.

The red light-emitting layer 321 contains a hole-transporting host material. Therefore, the red light emitting layer 321 can have the hole transport function of the hole transport layer 51 . Here, the hole-transporting host material used is not particularly limited as long as it has a hole-transporting function, and examples thereof include benzidines, triamines, tetramines, triarylamines, 4,4' -Bis(diarylamino)biphenyls, p-phenylenediamine derivatives, m-phenylenediamine derivatives, 1,1-bis(4-diarylaminophenyl)cyclohexanes, 4,4' -Bis(diarylamino)biphenyls, aryl-bis(4-diarylaminophenyl)amines, distyrylarylenes, distyrylbenzenes, distyrylamine derivatives Compounds, quinolinolates metal complexes, azomethines, oxadiazoles, pyrazoloquinolines, silacyclopentadienes, naphthalene, anthracene, bicarbazole derivatives, Perylenes, oligothiophenes, coumarins, pyrene derivatives, tetraarylbutadienes, benzopyrans, europium complexes, rubrenes, quinacridone derivatives, triazoles Classes, benzoxazoles, benzothiazoles, 4-mers of triarylamines, etc. Among them, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, 4,4'-bis[N-(3-methylphenyl)-N-phenyl Amino]biphenyl, tris(8-quinolinolato)aluminum, 4,4'-bis(2,2'-diphenylvinyl)biphenyl, materials preferably exemplified for the hole injection layer 31, and the like.

Preferably, the red light emitting layer 321 contains at least one red dopant. As a result, the whiteness of the organic electroluminescent element can be further increased.

The red dopant contained in the red light-emitting layer 321 is not particularly limited as long as it has a red light-emitting function, and examples include anthracenes, tetracenes, pentacenes, pyrenes, europium complexes, benzopyrans, 4-(Methylene substituted with two electron-withdrawing groups)-4H-pyrans, 4-(Methylene substituted with two electron-withdrawing groups)-4H-thiopyrans, rhodamines, benzothioxanthenes, Porphyrin derivatives, phenoxazinones, periflantants, etc., among which 7-diethylaminobenzo[a]phenoxazin-9H-3-one, [2-tert-butyl-6-[trans -2-(2,3,5,6-tetrahydro-1,1,7,7-tetramethyl-benzo[i,j]quinazin-9-yl)vinyl]-4H-pyran- 4-ylidene]-1,3-propanedinitrile, [2-methyl-6-[trans-2-(2,3,5,6-tetrahydro-1,1,7,7-tetramethyl Base-benzo[i,j]quinazin-9-yl)vinyl]-4H-pyran-4-ylidene]-1,3-malononitrile, dibenzotetraphenyl periflantene, etc. The red dopant is preferably contained in an amount of 0.1 to 15 parts by weight relative to 100 parts by weight of the hole-transporting host material. As long as it is within this range, excellent whiteness can be obtained.

The hole mobility of the red light emitting layer 321 is preferably higher than that of the blue light emitting layer 320 . Thereby, luminous efficiency can be improved.

The hole mobility can be known, for example, by a time-of-flight (TOF) method. In this TOF method, a pulsed light is irradiated on the surface of a sample to which a voltage is applied, a transient current generated when holes generated by the pulsed light move in the sample (inside a layer), a voltage applied to the sample, and The hole mobility (unit: cm ² /V·s) can be calculated from the thickness of the sample. Specifically, a separate film (for example, a film of about 10 to 20 μm) of the layer whose hole mobility is to be measured is produced, and the hole mobility is measured using this film. The conditions for the strength of the applied electric field when measuring the hole mobility are within the range of the strength of the electric field applied when the organic EL element is actually used.

The red light-emitting layer 321 can be formed by forming a film of these materials on the hole transport layer 51 using known film-forming methods such as sputtering, ion plating, vacuum co-evaporation, spin coating, and electron beam co-evaporation. make.

"Light Adjustment Layer"

A light emission adjustment layer is preferably provided between the red light emitting layer 321 and the blue light emitting layer 320 described below. The luminous adjustment layer can further improve the balance of luminous intensity of red, green and blue by blocking electrons. The film thickness of the light emission adjusting layer is preferably 0.1 nm to 30 nm. It is further preferably 0.5-20 nm. As long as it is within this range, excellent whiteness can be obtained.

Materials that can be used for the light-emitting adjustment layer can use materials that block electrons such as hole-transporting materials. Examples include: triarylamines, 4,4'-diaminobiphenyl derivatives, and the preferred examples of the hole injection layer 31 Among them, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl is preferable because of its particularly excellent electron blocking performance.

The light emission adjustment layer can be formed by forming a film of these materials on the red light emitting layer 321 using known film forming methods such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation.

"Blue Luminous Layer 320"

The blue light-emitting layer 320 is disposed between the red light-emitting layer 321 or the light-emitting adjustment layer and the electron transport layer 54 . In the blue light emitting layer 320 , holes and electrons respectively injected from the anode 10 and the cathode 15 recombine to become an excited state, and emit blue light when returning to the ground state. As a material that can be used for the blue light-emitting layer 320 , any material can be selected from known materials having blue light-emitting performance.

The film thickness of the blue light emitting layer 320 is preferably thicker than that of the red light emitting layer 321 . Thereby, the color balance can be further improved. The film thickness of the blue light emitting layer 320 is preferably 1.1 times to 8 times the film thickness of the red light emitting layer 321 , more preferably 1.2 times to 6 times. More specifically, the film thickness of the blue light emitting layer 320 is preferably 0.6nm-70nm, more preferably 5nm-60nm.

The blue light emitting layer 320 preferably contains a bipolar host material and a blue dopant. Thereby, blue light can be emitted with good luminous efficiency.

The bipolar host material that can be used for the blue light-emitting layer 320 only needs to be a material with high hole transport performance and electron transport performance, for example: distyrylarenes, stilbenes, carbazole derivatives, triaryl Amines, bis(2-methyl-8-quinolinol)(p-phenylphenol)aluminum, 4,4'-bis(2,2-diarylvinyl)biphenyls, and the like.

The blue dopant that can be used in the blue light-emitting layer 320 is not particularly limited as long as it has blue light-emitting performance, for example: pyrenes, perylenes, anthracenes, distyrylamines, benzoxazoles , quinolinolide metal complexes, benzothiazoles, benzimidazoles, , phenanthrene, distyrylbenzene, distyrylarylene, divinylarylene, three Styrylarylenes, triarylethylenes, tetraarylbutadienes, etc. The doping amount of the blue dopant is preferably 2 times to 40 times that of the red dopant and the green dopant according to the weight ratio, more preferably 5 times to 30 times. As long as it is within this range, it is possible to obtain blue luminescence with balanced intensity of green luminescence from the green dopant and red luminescence from the red dopant, and excellent white light can be obtained from these luminescence.

The blue light-emitting layer 320 can use known film-forming methods such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation. It is made by forming a film.

"Electron Transport Layer 54"

The electron transport layer 54 is disposed between the blue light emitting layer 320 and the electron injection layer 34 . The electron transport layer 54 is a layer that transports electrons transported from the electron injection layer 34 to the blue light emitting layer 320 . The thickness of the electron transport layer 54 is preferably 1-50 nm, more preferably 10-40 nm.

The electron transport layer 54 may have a one-layer structure, but it is preferably a double-layer structure from the perspective of reducing the interaction between the electron transport layer material and the blue light-emitting layer material such as stimulated complex or CT complex formation. As a result, the lifetime of the organic electroluminescent element can be extended.

When the electron transport layer 54 has a one-layer structure, an electron transport material can be appropriately selected according to the luminous efficiency or device life required for the organic electroluminescent device. Specifically, from the perspective of improving luminous efficiency, electron transport materials with high electron mobility are preferably used as electron transport layer materials; from the perspective of prolonging device life, electron transport materials with low electron mobility are preferably used.

When the electron transport layer 54 has a double-layer structure, it is preferable to arrange the electron transport layer material with high electron mobility on the electron injection layer 34 side, and arrange the electron transport layer material with low electron mobility on the blue light emitting layer 320 side. Therefore, the electron transport layer material with low electron mobility acts as a buffer, which can reduce the above-mentioned interaction between the electron transport layer material with high electron mobility and the blue light-emitting layer material, maintain luminous efficiency, and prolong the life of the device. In this case, the film thickness of the layer containing the electron transport material with low electron mobility is preferably 0.1 to 2 times the film thickness of the layer containing the electron transport material with high electron mobility.

Here, materials for the electron transport layer with low electron mobility include metal phenoxides, quinolinolate-based metal complexes, triazole derivatives, oxazole derivatives, oxadiazole derivatives, quinoxaline derivatives, Pyrroline derivatives, pyrrole derivatives, benzopyrrole derivatives, tetraphenylmethane derivatives, pyrazole derivatives, thiazole derivatives, benzothiazole derivatives, thiadiazole derivatives, thienyl derivatives, spiro compounds , imidazole derivatives, benzimidazole derivatives, distyrylbenzene derivatives, etc., among which three (8-hydroxyquinoline) aluminum, bis (2-methyl-8-quinolinol) (p-phenylphenol )aluminum. Electron transport layer materials with high electron mobility include: phenanthroline derivatives, phenanthroline derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, quinoxaline derivatives, silacyclopentadiene ene derivatives, quinoline derivatives, pyrrole derivatives, benzopyrrole derivatives, tetraphenylmethane derivatives, pyrazole derivatives, thiazole derivatives, triphenylmethane derivatives, benzothiazole derivatives, thiadiene derivatives Azole derivatives, thiaindene derivatives, spiro compounds, imidazole derivatives, benzimidazole derivatives, distyrylbenzene derivatives, etc., among which 2,9-dimethyl-4,7-diphenylphenanthrene is preferred phenoline. These can be used alone or in combination as appropriate.

The electron transport layer 54 can be produced by forming a film of the above-mentioned materials on the blue light-emitting layer 320 using known film-forming methods such as sputtering, ion plating, vacuum evaporation, spin coating, and electron beam evaporation. .

"Electron Injection Layer 34"

The electron injection layer 34 is provided between the cathode 15 and the electron transport layer 54 . The electron injection layer 34 is a layer that forms a cathode interface layer and easily injects electrons from the cathode 15 to the electron transport layer 54 . The film thickness of the electron injection layer 34 is preferably 0.1 nm to 3 nm, more preferably 0.2 nm to 1 nm.

The material that can be used for the electron injection layer 34 can be adopted as long as it is a substance that makes the electron injection layer 34 have the above-mentioned properties, and is not particularly limited. For example, alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as strontium, magnesium, and calcium, and fluoride Lithium, lithium oxide, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride and other alkali metal compounds, alkaline earth metal fluorides, oxides, chlorides, sulfides, etc. Among them, lithium fluoride is preferable. The electron injection layer 34 may be formed of a single material, or may be formed of a plurality of materials.

The electron injection layer 34 can be produced by forming a film of these materials on the electron transport layer 54 using known film formation methods such as sputtering, ion plating, vacuum deposition, spin coating, and electron beam deposition.

"Cathode 15"

The cathode 15 is an electrode for injecting electrons into the electron injection layer 34. In order to improve the electron injection efficiency, metals or alloys, electrically conductive compounds and their mixtures with a work function such as lower than 4.5 eV can be used as electrode materials.

Examples of the above cathode materials are lithium, sodium, magnesium, silver, copper, aluminum, indium, calcium, tin, ruthenium, titanium, manganese, chromium, yttrium, aluminum-calcium alloys, aluminum-lithium alloys, aluminum-magnesium alloys, Magnesium-silver alloy, magnesium-indium alloy, lithium-indium alloy, sodium-potassium alloy, sodium-potassium alloy, magnesium/copper mixture, aluminum/alumina mixture, etc. Materials usable as materials for anodes can also be used. Among them, aluminum is preferable.

When the cathode 15 is arranged on the side closer to the light extraction side than the red luminescent layer 321 and the blue luminescent layer 320, it is generally set to have a transmittance greater than 10% for the extracted light, for example, it can be used on an ultra-thin magnesium-silver alloy Electrodes, etc. formed by laminating transparent conductive oxides. In this cathode 15 , a buffer layer containing copper phthalocyanine or the like may be provided between the cathode 15 and the electron injection layer 34 in order to prevent the light-emitting layer and the like from being damaged by plasma during sputtering of the conductive oxide.

When used as a light-reflective electrode, a material capable of reflecting extracted light to the outside can be appropriately selected from the above-mentioned materials, and usually a metal, an alloy, or a metal compound is selected.

The cathode 15 may be formed of the above materials alone, or may be formed of a plurality of materials. For example, adding 1-20% by weight of silver or copper to magnesium, or adding 0.1-10% by weight of lithium to aluminum can prevent the oxidation of the cathode 15, and the adhesion between the cathode 15 and the electron injection layer 34 is also improved. improve.

The cathode 15 may have a multilayer structure including layers of the same composition or different compositions. For example, the following structures can be used.

• In order to prevent the oxidation of the cathode 15, a protective layer containing a corrosion-resistant metal is provided on the portion of the cathode 15 that is not in contact with the electron injection layer 34.

As a material for forming the protective layer, for example, silver or aluminum can be preferably used.

The cathode 15 can be formed on the electron injection layer 34 or the protective layer by known thin film forming methods such as vacuum evaporation, sputtering, ionization evaporation, ion plating, and electron beam evaporation.

The film thickness of the cathode 15 (thickness not including the protective layer) varies depending on the electrode material used, and is usually about 5nm-1μm, preferably about 5-700nm, particularly preferably about 10-500nm, most preferably set at 50-200nm .

The surface resistance of the cathode 15 is preferably set to several hundred ohms/sheet or less.

As described above, the organic EL element in the second embodiment may have any one of the following configurations (9) to (13), and other parts may be appropriately modified.

(9) At least a hole transport layer, an organic light-emitting layer and a cathode are sequentially arranged on the anode, and the above-mentioned organic light-emitting layer is sequentially provided with a red light-emitting layer and a blue light-emitting layer from the side of the hole transport layer, and the red light-emitting layer contains a green dopant composition.

(10) In the configuration of (9) above, a configuration in which an emission adjustment layer is provided between the red emitting layer and the blue emitting layer.

(11) In the configuration of (9) or (10) above, the thickness of the blue light-emitting layer is larger than the thickness of the red light-emitting layer.

(12) In the configuration of any one of the above (9) to (11), the red light-emitting layer contains a hole-transporting material, a red dopant, and a green dopant.

(13) In the configuration of any one of (9) to (12) above, a configuration in which the hole mobility of the red light-emitting layer is higher than that of the blue light-emitting layer.

(14) In the composition of any one of the above (9)-(13), the blue light-emitting layer contains at least one selected from the group consisting of distyrylamine derivatives, pyrenes, perylenes, anthracenes, and benzoxazoles. Classes, benzothiazoles, benzimidazoles, s, phenanthrenes, distyrylbenzenes and tetraarylbutadiene blue dopants, and at least one selected from the group consisting of distyryl aryl Acrylidenes, stilbenes, carbazole derivatives, triarylamines, bis(2-methyl-8-quinolinol) (p-phenylphenol) aluminum and 4,4'-bis(2,2'-di Bipolar host material of phenylvinyl)biphenyl.

A color display device using the above-mentioned organic electroluminescent element is shown in FIGS. 6 and 7 .

FIG. 6 is a schematic configuration diagram of the overall configuration of the color display device 101 . The color display device 101 is composed of a controller 102 , a data driver 103 , a scan driver 104 and an organic electroluminescence panel 105 .

The controller 102 of the color display device 101 is connected to a data driver 103 and a scan driver 104 . The controller 102 outputs display signals (scan signals) for displaying display data on the organic electroluminescence panel 105 to the data driver 103 and the scan driver 104 according to the input display data and control signals.

The data driver 103 is connected to an anode 107 formed on the organic electroluminescence panel 105 , and the scan driver 104 is connected to a cathode 108 formed on the organic electroluminescence panel 105 . The data driver 103 incorporates a constant current drive circuit 106 .

Next, the organic electroluminescent panel 105 will be described. FIG. 7 is a schematic cross-sectional view of the organic electroluminescent panel 105 along the cathode 108 . As shown in FIG. 7 , the organic electroluminescent panel 105 includes a transparent substrate 109, an organic electroluminescent element 110 formed on the surface of the transparent substrate 109, and a Color filter (CF) 112 .

The data driver 103 performs switching according to the display signal to make the pixels of the organic electroluminescent panel 105 emit light, and supplies the current corresponding to the display signal to the organic electroluminescent element 110 through the constant current driving circuit 106 and via the anode 107 . The scan driver 104 is connected to a constant power source (eg, ground) of the cathode 108 corresponding to the display signal. Thus, the current injected into the organic electroluminescent element 110 corresponds to the brightness of the displayed display data.

The color filter 112 is arranged in a position corresponding to the organic electroluminescent element 110 at a fixed distance from the organic electroluminescent element 110, and the emission direction of light is toward the shield (caba-) plate 111 side.

The protective plate 111 is fixed on the substrate via a sheet 113 . That is, the organic electroluminescence element 110 is surrounded by the substrate 109 , the sheet 113 and the guard plate 111 .

The organic electroluminescent element 110 can use the organic electroluminescent element of the second embodiment. The organic electroluminescent element 110 is covered with a protective film 115 except for the surface opposite to the substrate 109 . The protective film 115 is formed of a material that prevents moisture from permeating.

The anode 107 forms a plurality of parallel stripes on the surface of the substrate 109 . In FIG. 7 , the anode 107 is formed extending along a direction perpendicular to the paper. The organic electroluminescent layer 114 is formed in a plurality of parallel stripes extending in a direction perpendicular to the anode 107 .

The cathode 108 is laminated on the striped organic electroluminescent layer 114 to be perpendicular to the anode 107 . Pixels constituting the organic electroluminescent element 110 are arranged in a matrix on the substrate 109 at the intersection of the anode 107 and the cathode 108 . The cathode 108 is formed to be transparent in order to transmit light emitted from the organic electroluminescent layer 114 .

The R (red light), G (green light), and B (blue light) of the organic electroluminescent element 110 have a luminous peak wavelength of 580nm-680nm and a half-value width of 10nm-140nm, and a luminous peak wavelength of 510nm-550nm and a luminous peak wavelength of 10nm. -140nm half value width, and 440nm-490nm luminescence peak wavelength and 10nm-140nm half value width.

The R (red), G (green), and B (blue) pixels (not shown) of the color filter 112 respectively have an upward transmission peak wavelength of 560nm, a transmission peak wavelength of 510nm-550nm and a transmission peak wavelength of 140nm or below (for example, 80nm-140nm ), and a transmission peak wavelength of 450nm-490nm and a half-value width of 140nm or less (for example, 80nm-140nm).

With the emission peak wavelength of the organic electroluminescence element 110 as the center, the emission region of the organic electroluminescence element 110 as a range in which the half-value width of the emission peak wavelength is increased or decreased is included in the range where the transmission peak wavelength of the color filter 112 is The center is within the transmission region of the color filter 112 which is a range in which the half-value width of the transmission peak wavelength is increased or decreased. With regard to the transmission peak wavelength of the R (red) pixel of the color filter 112, 560 nm upward means that any light with a wavelength longer than 560 nm may be included. Light with a wavelength longer than 560 nm is due to having lower energy than light with a wavelength of 560 nm. Only the lower limit of the wavelength is set in this way, so the half-value width is not particularly set.

Next, the operation of the above-mentioned color display device 101 will be described. The controller 102 outputs display signals to the data driver 103 and the scan driver 104 according to the input display data and control signals. Based on the display signal output by the controller 102, the constant current driving circuit 106 injects a current corresponding to display data between the anode 107 and the cathode 108 of the portion to be lighted. The white light emitted by the injected current passes through the color filter 112 and is emitted from the guard plate 111 side. After the white light passes through the R (red), G (green), and B (blue) pixels of the color filter 112 , it becomes light of the corresponding color. Desired colors can be reproduced by combining R (red), G (green), and B (blue) pixels.

By making the emission characteristics of the organic electroluminescent element 110 and the transmission characteristics of the color filter 112 within the aforementioned ranges, the emission wavelength range of each color is included in the transmission wavelength range, so that beautiful color development can be effectively obtained.

In the above embodiments, the color filter 112 may use an inorganic color filter or an organic color filter. In the above-mentioned embodiments, the color display device 101 is realized by a passive matrix method, but it can also be realized by an active matrix method by allowing any electrode side to have a switching function.

Next, a liquid crystal display device using the above-mentioned organic electroluminescence element as a backlight will be described. As shown in FIG. 9 , a liquid crystal display device 200 includes a liquid crystal panel 201 and a backlight 202 . The liquid crystal panel 201 is known and has a plurality of pixels, and R (red), G (green), and B (blue) color filters (not shown) are provided corresponding to each pixel. By adjusting the voltage applied to the electrodes provided across the liquid crystal, the amount of light passing through each pixel is adjusted. Here, the characteristics of R, G, and B color filters are preferably 560nm upward transmission peak wavelength, 510nm-550nm transmission peak wavelength and half-value width of 140nm or below (eg 80nm-140nm), and 450nm-490nm transmission peak Wavelength and half value width of 140nm or below (eg 80nm-140nm).

The backlight 202 is constituted by the organic electroluminescence element shown in the second embodiment. The organic electroluminescent element constituting the backlight 202 is sequentially stacked on the transparent substrate 203 along the downward direction in FIG. The electrodes or organic compounds of the electroluminescent element are isolated from external moisture or oxygen.

The anode 204, the organic layer 205, and the cathode 206 are all formed to have approximately the same size as the substrate, and when a current flows from the anode 204 to the cathode 206, all elements emit light at the same time.

As described in the second embodiment, the organic layer 205 has at least a red light-emitting layer and a blue light-emitting layer, and the red light-emitting layer contains a green light-emitting dopant. When the current is injected, the organic layer 205 emits white light. The luminescence has the following characteristics: luminescence peak wavelength of 580nm-680nm and half-value width of 10nm-140nm, luminescence peak wavelength of 510nm-550nm and half-value width of 10nm-140nm, and luminescence peak wavelength of 440nm-490nm and 10nm-140nm The half-value width of .

The operation of the liquid crystal display device 200 configured in this way will be described. A signal from a liquid crystal panel driving device (not shown) is input to the liquid crystal panel 201 , and the light transmittance in each pixel of the liquid crystal panel 201 is determined based on the signal. At the same time, current is injected from the anode 204 of the backlight 202 to the cathode 206, and the backlight 202 emits white light. The light emitted from the backlight 202 enters the liquid crystal panel 201, and passes through each pixel and color filter to reach the observer's eyes. At this time, the amount of light passing through the pixels of the liquid crystal panel 201 is adjusted, and the wavelength region of the passing light is further limited by the color filter. In this way, the entire liquid crystal display device displays desired images and the like.

In such a liquid crystal display device 200, by making the transmission characteristics of the color filter of the liquid crystal panel 201 and the emission characteristics of the organic electroluminescence elements constituting the backlight 202 within the above-mentioned range, the emission wavelength range of each color is included in the transmission wavelength range. range for beautiful hair color effectively.

[Example]

Examples and comparative examples of the present invention are described below, but the present invention is of course not limited and interpreted as the following examples.

<Example 1>

A transparent glass (substrate) 1 having an anode 10 (ITO layer with a film thickness of 250 nm) formed on one surface was prepared, and substrate cleaning was performed. The washing of the substrate is followed by alkali washing, pure water washing, and ultraviolet ozone washing after drying.

Using a vacuum evaporation device (carbon crucible, evaporation rate of 0.1nm/s, vacuum degree of about 5.0× ^10-5 Pa), the following formula with a film thickness of 50nm was produced on the anode 2 of the glass 1 after substrate cleaning The layer of N,N'-bis(4'-diphenylamino-4-biphenylyl)-N,N'-diphenylbenzidine shown in (1) is used as a hole injection transport layer 11.

The following ^formula (2 ) represented by 4,4'-bis(2,2'-diphenylvinyl)biphenyl (93.0% by weight), and 4,4'-(bis(9-ethane) represented by the following formula (3) (3-carbazolylvinylidene)-1,1′-biphenyl (7.0% by weight) was used as the light-emitting layer 12 .

Through a vacuum evaporation device (carbon crucible, evaporation speed is 0.1nm/s, vacuum degree is about 5.0× ^10-5 Pa), on the light-emitting layer 12, the co-evaporated 5nm film thickness is shown in the following formula (4): Tris(8-hydroxyquinoline)aluminum (37% by weight), and 4,4'-bis(2,2'-diphenylvinyl)biphenyl (63% by weight) represented by the above formula (2) The layer, with this layer as the non-emissive layer 13.

By vacuum evaporation device (carbon crucible, evaporation rate is 0.1nm/s, vacuum degree about 5.0 × 10 ^-5 Pa), on the non-luminescent layer 13, make 2 shown in the following formula (5) with a film thickness of 15nm, A layer of 5-bis(6'-(2',2"-bipyridyl))-1,1-dimethyl-3,4-diphenylsilacyclopentadiene for electron injection transport layer 14.

A lithium fluoride layer with a film thickness of 0.5 nm is formed on the electron injection transport layer 14 by a vacuum evaporation device (carbon crucible, evaporation rate is 0.1 nm/s, vacuum degree is about 5.0 × 10 ^-5 Pa), and the layer is the cathode interface layer.

A 150nm-thick aluminum layer is formed on the electron injection and transport layer 14 by a tungsten boat (evaporation speed is 1nm/s, vacuum degree is about 5.0× ^10-5 Pa), and this layer is used as the cathode 15 to make an organic electroluminescent electrode. light emitting element.

The organic electroluminescent element made is packaged with glass caps (Kisetsupu), connected the anode 10 and the cathode 15 by a known driving circuit, and measured the electric power (lm/W) and the ^initial luminance half-decay life (brightness) under the luminance of 1600cd/m time to 2400cd/ ^m2 , hr), where the initial luminance half-life is the half-life when the current at which the initial luminance is set to 4800cd/ ^m2 continues to flow. The luminance was measured with a luminance meter (manufactured by Topcon Corporation, trade name BM7). The measurement results are shown in Table 1.

<Comparative example 1>

In Comparative Example 1, an organic EL element was produced in the same manner as in Example 1 except that the non-light-emitting layer 13 was not provided. About the produced organic EL element, the electric power and initial luminance half-life were measured similarly to Example 1. The measurement results are shown in Table 1.

<Example 2-6>

In Examples 2-6, the addition ratios of tris(8-quinolinolato)aluminum in the non-luminous layer were changed to 9% by weight, 15% by weight, 40% by weight, 50% by weight, and 65% by weight, except that Other than that, an organic EL element was produced in the same manner as in Example 1. About the produced organic EL element, the electric power and initial luminance half-life were measured similarly to Example 1. The measurement results are shown in Table 1.

<Example 7-8>

In Examples 7-8, an organic EL element was fabricated in the same manner as in Example 1 except that the film thickness of the light-emitting layer 12 was changed to 30 nm, and the film thickness of the non-light-emitting layer 13 was changed to 25 nm and 20 nm. About the produced organic EL element, the electric power and initial luminance half-life were measured similarly to Example 1. The measurement results are shown in Table 2.

<Example 9>

In Example 9, the tris(8-quinolinolato)aluminum in the non-emitting layer 13 was changed to the 2,5-bis(6'-(2',2"-bipyridyl) shown in (5) above )-1,1-dimethyl-3,4-diphenylsilacyclopentadiene, except that an organic EL element was produced in the same manner as in Example 1. For the organic EL element produced, the same as in Example 1 The electric power and initial luminance half-life were measured in the same way.The measurement results are shown in Table 3.

Table 1: Alq3 doping amount and electric power · half-life life Alq3 doping amount (w%) Electric power (1m/W) Half-life (hr) Example 1 37 9.61 238 Example 2 9 10.02 125 Example 3 15 9.61 133 Example 4 40 8.89 220 Example 5 50 8.14 300 Example 6 65 7.67 350 Comparative example 1 0 10.4 67

Table 2: Film thickness and electric power·half-life of the non-emitting layer 13 Thickness of non-emitting layer (nm) Electric power (1m/W) Half-life (hr) Example 4 5 8.89 220 Example 7 15 8.30 243 Example 8 30 8.01 275 Comparative example 1 0 10.4 67

Table 3: Materials contained in the non-emitting layer 13 and electric power and half-life Dopant for non-emitting layer Electric power (1m/W) Half-life (hr) Example 1 37w% Alq3 9.61 238 Example 9 37w% above formula (5) 10.9 146 Comparative example 1 none 10.4 67

In each example, the electron mobility and hole mobility of the non-emitting layer 13 and the electron injection transport layer 14 were measured by the TOF method. The results show that: the non-emitting layer 13 has electron transport property, and the hole transport property is higher than that of the electron injection transport layer 14 . The spectrum of the produced organic EL element was measured by the above-mentioned luminance meter, and no light emission (peak wavelength) of the material contained in the non-emitting layer 13 was observed.

<Evaluation>

From Embodiments 1-9 and Comparative Example 1, it can be seen that comparing the cases where the non-luminous layer 13 is provided and the case where the non-luminous layer 13 is not provided, there is almost no change in electric power, and the half-life of the initial luminance is prolonged.

It can be known from Examples 1-6 and Comparative Example 1 that if the hole mobility of the non-emitting layer 13 is increased, the electric power will hardly change, and the half life of the initial luminance will be extended. As measured by the TOF method, in the non-emitting layer 13 of Example 6, the electron-transport property was greater than the hole-transport property.

The electron mobility and hole mobility of tris(8-quinolinolato)aluminum were measured by TOF method, and it can be seen that it has electron transport property, and the hole transport property is higher than that of the electron injection transport layer. From this result, Examples 1-8 and Comparative Example 1, it can be seen that the non-emitting layer 13 may contain a material having electron transport properties and higher hole transport properties than the electron injection transport layer.

From Example 9 and Comparative Example 1, it can be seen that the effect of the present invention can also be obtained in the non-emitting layer 13 containing the material contained in the electron injection transport layer and the hole transport material.

From Examples 1 to 8 and Comparative Example 1, it can be seen that the effect of the present invention can also be obtained by using the material (host) contained in the light-emitting layer 12 as the hole-transporting material.

From Examples 4, 7, 8 and Comparative Example 1, it can be seen that increasing the film thickness of the non-luminous layer 13 increases the initial luminance half life.

<Example 10>

A transparent glass (substrate) 2 having an anode 10 (ITO layer with a film thickness of 170 nm) formed on one surface was prepared, and substrate cleaning was performed. The washing of the substrate is followed by alkali washing, pure water washing, and excitonic ultraviolet washing after drying.

Through a vacuum evaporation device (carbon crucible, evaporation speed is 0.1nm/s, vacuum degree is about 5.0×10 ^-5 Pa), on the anode 10, make tris[4-[N-(3-methyl A layer of phenyl)-N-phenylamino]phenyl]amine is used as the hole injection layer 31 .

A ^70nm -thick 4,4'-bis A layer of [N-(1-naphthyl)-N-phenylamino]biphenyl is used as the hole transport layer 51 .

Using a vacuum evaporation device (carbon crucible, evaporation rate of 0.1nm/s, vacuum degree of about 5.0×10 ^-5 Pa), on the hole transport layer 51, a co-evaporated 5nm film-thick red light-emitting layer host material was produced. 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, red dopant [2-tert-butyl-6-[trans-2-(2,3,5 , 6-tetrahydro-1,1,7,7-tetramethyl-benzo[i,j]quinazin-9-yl)vinyl]-4H-pyran-4-ylidene]-1,3 - A layer of malononitrile (0.5% by weight) and a green light-emitting dopant N,N′-dimethylquinacridone (1% by weight), which is used as the red light-emitting layer 321 .

Using a vacuum evaporation device (carbon crucible, evaporation rate of 0.1nm/s, vacuum degree of about 5.0× ^10-5 Pa), co-evaporate on the red light-emitting layer 321 to produce a 25nm-thick blue light-emitting layer host material 4 , 4'-bis(2,2'-diphenylvinyl)biphenyl, blue dopant 4,4'-bis[2-(N-ethylcarbazol-2-yl)vinyl]bis A layer of benzene (3% by weight) was used as the blue light-emitting layer 320 .

The hole mobility of the red light-emitting layer and the hole mobility of the blue light-emitting layer were measured, and it was found that the hole mobility of the red light-emitting layer was high.

Determination of the hole mobility and electron mobility of 4,4'-bis(2,2'-diphenylvinyl)biphenyl, the result of 4,4'-bis(2,2'-diphenylethenyl) Biphenyl is a bipolar material.

Tris(8-hydroxyquinoline)aluminum with a film thickness of 15 nm was formed on the blue light-emitting layer 320 by a vacuum evaporation device (carbon crucible, evaporation rate of 0.1 nm/s, vacuum degree of about 5.0×10 ⁻⁵ Pa). layer, and this layer is used as the electron transport layer 54.

A lithium fluoride layer with a film thickness of 0.5 nm is formed on the electron transport layer 54 by a vacuum evaporation device (carbon crucible, evaporation rate is 0.1 nm/s, vacuum degree is about 5.0×10 ⁻⁵ Pa), and this layer is used as Electron injection layer 34 .

A 100nm-thick aluminum layer is formed on the electron injection layer 34 by a tungsten boat (evaporation speed is 1nm/s, vacuum degree is about 5.0×10 ^-5 Pa), and this layer is used as the cathode 15 to make an organic electroluminescence element.

The fabricated organic electroluminescent element is encapsulated with a glass cap. Measure the chromaticity coordinates, luminous efficiency (lm/W) and half-life of the initial luminance (set at 4800cd/m ² ) of the organic electroluminescent element at a luminance of 1600cd/m ² Lifetime (time when brightness becomes 2400cd/m ² ) and chromaticity change. The luminance was measured with a luminance meter (manufactured by Topcon Corporation, trade name BM7). The change in chromaticity is defined as the square root of the sum of the square root of the change in chromaticity x to the power of 2 and the change in chromaticity y to the power of 2. The amount of change in chromaticity is the difference between the initial chromaticity and the chromaticity when the brightness is half-decayed. Table 4 shows the measurement results and the like.

When the emission spectrum is measured by a spectrometer (manufactured by Topcon Co., Ltd., trade name SR-2), the emission spectrum is 440 nm or more but 490 nm or less, 510 nm or more but 550 nm or less, and 580 nm or more but 680 nm or less The region has a maximum point.

<Example 11-32>

In Examples 11-32, substrate 2 , anode 10 , hole transport layer 51 , blue light emitting layer 320 , electron injection layer 34 , and cathode 15 were formed in the same manner as in Example 10.

The other layers were formed from the materials summarized in Tables 4 and 5 below. Compound numbers in Tables 4 and 5 are as follows.

1: Tris(8-hydroxyquinoline)aluminum

2: 4,4'-bis(2,2'-diphenylvinyl)biphenyl

3: 4,4'-bis[2-(N-ethylcarbazol-2-yl)vinyl]biphenyl

4: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl

5: [2-tert-butyl-6-[trans-2-(2,3,5,6-tetrahydro-1,1,7,7-tetramethyl-benzo[i,j]quinazine -9-yl)vinyl]-4H-pyran-4-ylidene]-1,3-malononitrile

6: N, N'-Dimethylquinacridone

7: Tris[4-[N-(3-methylphenyl)-N-phenylamino]phenyl]amine

8: 2,9-Dimethyl-4,7-diphenylphenanthroline

9: 4,4'-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl

10: 7-Diethylaminobenzo[a]phenoxazin-9H-3-one

11: cis-2-(1,3-benzothiazol-2-yl)-3-(8-hydroxy-2,3,5,6-tetrahydro-1,1,7,7-tetramethyl -Benzo[i,j]quinazin-9-yl)acrylate lactone

12: Tris[4-[N-(2-naphthyl)-N-phenylamino]phenyl]amine

13: Dibenzo[c,n]quinacridone

14: Porphyrin-copper(II) complex

15: [2-Methyl-6-[trans-2-(2,3,5,6-tetrahydro-1,1,7,7-tetramethyl-benzo[i,j]quinolazine- 9-yl)vinyl]-4H-pyran-4-ylidene]-1,3-malononitrile

16: 3-(1,3-Benzothiazol-2-yl)-7-diethylaminocoumarin

17: Dibenzo[f,g:s,t]pentacene

18: 7'-aza-8'-cyclohexyl-9-cyanantro[10a, 10-a: 9, 9a-m: 5, 10a-1] anthracen-10-one

19: Dibenzotetraphenyl periflantene

20: Antoro [7, 6-o: 6, 5a-p: 5a, 5-q: 5, 4a-r: 4a, 4-s] tetracene

21: Dinaphtho[2,1-d:1,8a-e:8a,8-f:8,7-g][4,3-j]anthracene

22: Dibenzo[d,e:u,v]pentacene

Only in Example 11, the electron transport layer 54 is successively laminated with 7.5nm 2,9-dimethyl-4,7-diphenylphenanthroline (8) and tris(8-hydroxyquinone) from the cathode side. phylloline) aluminum (1), forming a bilayer structure. In Examples 12 to 32, the electron transport layer 54 was formed in the same manner as in Example 10.

The hole mobility of the red light-emitting layer of Examples 11-32 and the hole mobility of the above-mentioned blue light-emitting layer were measured, and it was found that the hole mobility of the red light-emitting layer was high.

In Examples 11, 12, 14, 16, 18, 20, 22, 24, 26 and 28, 4,4'-bis[N-(1 -Naphthyl)-N-phenylamino]biphenyl (4) to form an emission adjusting layer with a film thickness of 1 nm.

As shown in Tables 4 and 5 below, the red light emitting layer 321 and the hole injection layer 31 were formed by evaporation of various materials. Only in Example 12, the host material of the red light-emitting layer 321 uses 4,4'-[N-(3-methylphenyl)-N-phenylamino]biphenyl (9), and in Examples 11 and 13 -32 was formed using 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (4) in the same manner as in Example 10.

Regarding the luminescence of the organic EL elements produced in Examples 11-32, in the same manner as in Example 10, the chromaticity coordinates of the luminescent color at a luminance of 1600cd/m ² , the luminous efficiency (1m/W) and the time of continuous current flow were measured. The initial luminance (set to 4800cd/m ² ) half-life (the time when the luminance becomes 2400cd/m ² ) and chromaticity change. The luminance was measured with a luminance meter (manufactured by Topcon Corporation, trade name BM7). The change in chromaticity is defined as the square root of the sum of the change in chromaticity x to the power of 2 and the change in chromaticity y to the power of 2. The amount of change in chromaticity is the difference between the initial chromaticity and the chromaticity when the brightness is half-decayed. The measurement results and the like are shown in Tables 4 and 5.

When the emission spectrum is measured by a spectrometer, the emission spectrum has a maximum point in the region of 440nm or more but 490nm or less, 510nm or more but 550nm or less, and 580nm or more but 680nm or less.

Table 4 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Component structure cathode Al Al Al Al Al Al Al Al al al electron injection layer LiF LiF LiF LiF LiF LiF LiF LiF LiF LiF electron transport layer 1 1 and 8 1 1 1 1 1 1 1 1 blue luminous layer main body 2 2 2 2 2 2 2 2 2 2 blue dopant 3 3 3 3 3 3 3 3 3 3 Luminescence adjustment layer none 4 4 none 4 none 4 none 4 none red luminous layer main body 4 4 9 4 4 4 4 4 4 4 red dopant 5 5 10 5 15 17 18 10 5 18 green dopant 6 6 11 13 16 11 6 16 16 16 hole transport layer 4 4 4 4 4 4 4 4 4 4 hole injection layer 7 7 12 14 14 14 14 14 12 12 anode ITO ITO ITO ITO ITO ITO ITO ITO ITO ITO Substrate Glass Glass Glass Glass Glass Glass Glass Glass Glass Glass Evaluation results Color coordinates x 0.32 0.32 0.33 0.32 0.32 0.33 0.31 0.32 0.31 0.3 the y 0.31 0.32 0.33 0.31 0.32 0.33 0.31 0.32 0.33 0.32 Luminous efficiency (Im/W) 12.8 11.1 10.2 12.3 12.1 12.5 11.9 12.3 11.2 10.2 Component life (hr) 345 378 367 432 333 502 307 328 449 346 Chromaticity change 0.007 0.007 0.006 0.007 0.009 0.006 0.01 0.008 0.006 0.008

table 5 Example 20 Example 21 Example 22 Example 23 Example 24 Example 25 Example 26 Example 27 Example 28 Example 29 Example 30 Example 31 Example 32 Component structure cathode Al Al Al Al al al al al Al Al Al Al Al electron injection layer LiF LiF LiF LiF LiF LiF LiF LiF LiF LiF LiF LiF LiF electron transport layer 1 1 1 1 1 1 1 1 1 1 1 and 8 1 and 8 1 and 8 blue luminous layer main body 2 2 2 2 2 2 2 2 2 2 2 2 2 blue dopant 3 3 3 3 3 3 3 3 3 3 3 3 3 Luminescence adjustment layer 4 none 4 none 4 none 4 none 4 none 4 none none red luminous layer main body 4 4 4 4 4 4 4 4 4 4 4 4 4 red dopant 19 15 5 10 20 twenty one 17 twenty two 19 5 19 10 twenty one green dopant 16 13 6 13 16 11 11 11 13 13 16 13 11 hole transport layer 4 4 4 4 4 4 4 4 4 4 4 4 4 hole injection layer 12 12 12 14 12 14 12 14 8 8 12 14 14 anode ITO ITO ITO ITO ITO ITO ITO ITO ITO ITO ITO ITO ITO Substrate Glass Glass Glass Glass Glass Glass Glass Glass Glass Glass Glass Glass Glass Evaluation results Color coordinates x 0.31 0.32 0.33 0.32 0.31 0.3 0.31 0.32 0.32 0.33 0.33 0.32 0.31 the y 0.31 0.32 0.33 0.32 0.31 0.32 0.31 0.32 0.32 0.32 0.31 0.32 0.33 Luminous efficiency (Im/W) 12.4 11 11.7 10.9 10.2 11.2 9.9 12.4 12.3 11.3 12.8 11.3 11.7 Component life (hr) 478 300 344 341 348 332 344 299 431 332 331 236 256 Chromaticity change 0.006 0.01 0.009 0.009 0.008 0.006 0.01 0.009 0.009 0.01 0.006 0.009 0.006

<Comparative example 2-5>

Using the materials shown in Table 6 below, an organic electroluminescent element of a comparative example in which the stacking order of the red light-emitting layer and the blue light-emitting layer was different from that of the organic electroluminescent element of the present invention was produced in the same manner as in the examples. The compound numbers in Table 6 are the same as those in Table 4 and Table 5 above.

In the same manner as in the examples, the chromaticity coordinates of the luminous color of the organic electroluminescent element of the comparative example, the luminous efficiency (1m/W) at a luminance of 1600cd/m ² , and the initial luminance (setting 4800cd/m ² ) half-life (the time when the luminance becomes 2400cd/m ² ) and chromaticity change. The luminance was measured with a luminance meter (manufactured by Topcon Corporation, trade name BM7). The change in chromaticity is defined as the square root of the sum of the change in chromaticity x to the power of 2 and the change in chromaticity y to the power of 2. The amount of change in chromaticity is the difference between the initial chromaticity and the chromaticity when the brightness is half-decayed. Table 6 shows the measurement results and the like.

Table 6 Comparative example 2 Comparative example 3 Comparative example 4 Comparative Example 5 Component structure cathode Al Al Al Al electron injection layer LiF LiF LiF LiF electron transport layer 1 and 8 1 and 8 8 8 red luminous layer main body 4 1 4 1 red dopant 5 5 5 5 green dopant 6 6 6 6 Luminescence adjustment layer none none none none blue luminous layer main body 2 2 2 2 blue dopant 3 3 3 3 hole transport layer 4 4 4 4 hole injection layer 7 7 7 7 anode ITO ITO ITO ITO Substrate Glass Glass Glass Glass Evaluation results Color coordinates x 0.33 0.31 0.32 0.32 the y 0.55 0.34 0.55 0.34 Luminous efficiency (Im/W) 4.2 5.3 4.4 5.5 Component life (hr) 182 221 112 144 Chromaticity change 0.007 0.011 0.013 0.013

It can be known from Tables 4-6 that in the organic electroluminescent elements of the examples, the chromaticity coordinates of the luminescent colors all show excellent whiteness. On the other hand, in the organic electroluminescence element of the comparative example, the value of the y-coordinate especially among the chromaticity coordinates was large, and the whiteness was not excellent.

Compared with the organic electroluminescent element of the comparative example, the organic electroluminescent element of the example has significantly improved luminous efficiency and element life.

Therefore, it can be seen that in the organic electroluminescence element of the embodiment, the red light-emitting layer (containing red light-emitting dopant and green light-emitting dopant), blue light-emitting layer (containing blue light-emitting dopant) and blue light-emitting layer (containing blue light-emitting dopant) are sequentially arranged from the anode side. impurity), can obtain excellent whiteness, and can obtain high luminous efficiency and long device life at the same time.

Claims (18)

1. organic electroluminescent device, this organic electroluminescent device is sequentially with luminescent layer at least on anode, electronics injects transport layer and negative electrode, it is characterized in that: be provided with tool electron-transporting and hole transport ability are injected the transmission floor height than above-mentioned electronics not luminescent layer between electronics injection transport layer and the luminescent layer.

2. the organic electroluminescent device of claim 1, it is characterized in that: the electron-transporting of above-mentioned not luminescent layer is than hole transport ability height.

3. claim 1 or 2 organic electroluminescent device is characterized in that: above-mentioned not luminescent layer contains and possesses electron-transporting and hole transport ability are injected the transmission floor height than above-mentioned electronics material.

4. claim 1 or 2 organic electroluminescent device, it is characterized in that: above-mentioned not luminescent layer contains one or more electron transporting material that possess electron-transporting and possesses one or more hole transport ability materials that inject the hole transport ability of transmission floor height than above-mentioned electronics.

5. the organic electroluminescent device of claim 4 is characterized in that: at least a material of above-mentioned electron transporting material is an at least a identical materials of injecting the material that transport layer contains with above-mentioned electronics.

6. claim 4 or 5 organic electroluminescent device is characterized in that: at least a material of above-mentioned hole transport ability material be with above-mentioned luminescent layer at least a identical materials of the material that contains.

7. each organic electroluminescent device among the claim 4-6, it is characterized in that: the electron-transporting of above-mentioned electron transporting material is than the hole transport ability height of above-mentioned hole transport ability material.

8. each organic electroluminescent device among the claim 1-7, it is characterized in that: the hole transport ability of above-mentioned luminescent layer is than electron-transporting height.

9. organic electroluminescent device, this organic electroluminescent device is provided with organic luminous layer and negative electrode successively on anode, it is characterized in that: above-mentioned organic luminous layer sets gradually red light emitting layer and blue light-emitting layer by anode one side, and red light emitting layer contains at least a green light dopant.

10. the organic electroluminescent device of claim 9 is characterized in that: its luminescent spectrum is at 440nm to 490nm, 510nm to 550nm, and have maximal point in the zone of 580nm to 680nm.

11. the organic electroluminescent device of claim 9 or 10 is characterized in that: be provided with luminous regulating course between above-mentioned red light emitting layer and the above-mentioned blue light-emitting layer.

12. each organic electroluminescent device among the claim 9-11 is characterized in that: the thickness of the above-mentioned red light emitting layer of Film Thickness Ratio of above-mentioned blue light-emitting layer is thick.

13. each organic electroluminescent device among the claim 9-12 is characterized in that: above-mentioned red light emitting layer contains at least a dopant that glows.

14. each organic electroluminescent device among the claim 9-13 is characterized in that: the hole mobility of above-mentioned red light emitting layer is than the hole mobility height of above-mentioned blue light-emitting layer.

15. each organic electroluminescent device among the claim 9-14, it is characterized in that: above-mentioned blue light-emitting layer contains at least a pyrene class perylene class that is selected from, anthracene class Benzooxazole kind, the talan yl amine derivatives, benzothiazoles, benzimidazole, the class, luxuriant and rich with fragrance class, the blue dopant of diphenylethyllene benzene class and four aryl butadiene types, with at least a Stilbene class that is selected from, carbazole derivates, diphenylethyllene arylene class, the triaryl amine, two (2-methyl-8-quinolinol) (p-phenyl phenol) aluminium and 4, the bipolarity material of main part of 4 '-two (2,2-diarylethene base) biphenyl class.

16. each organic electroluminescent device among the claim 9-15 is characterized in that: above-mentioned green light dopant is be selected from coumarin derivative and quinacridone derivative at least a.

17. colour display device, this colour display device possess among the claim 1-16 each organic electroluminescent device and absorb at least a filter of a part of the luminescent spectrum of this organic electroluminescent device.

18. the colour display device of claim 17, wherein the light-emitting zone of above-mentioned organic electroluminescent device is at the regional transmission of above-mentioned filter.

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