JPH04334894A - Organic thin film type electroluminescence element - Google Patents

Abstract

PURPOSE:To improve emission luminance and lengthen the life of electroluminescence element by installing a layer made up of a specific material in an organic compound layer. CONSTITUTION:An anode 2, an organic compound layer made up of a layer 3a containing hole transporting luminescent material and a layer 3b where hole transporting luminescent material coexists with electron transporting material, and a cathode 4 are formed in order on a substrate 1. According to that constitution, the holes injected from an electrode and electrons are recombined over the whole of a coexistent layer 3b so as to emit light. Luminescent sight, therefore, more greatly increases in comparison with the previous cases so that emission luminance and luminous efficacy are improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a light-emitting layer made of a luminescent substance, and can directly convert electrical energy into light energy by applying an electric field, which is different from conventional incandescent lamps, fluorescent lamps, light-emitting diodes, etc. The present invention relates to an electroluminescent device that enables the realization of a large-area planar light emitter.

0002

[Prior Art] Due to differences in the luminescence excitation mechanism of electroluminescent elements, (1) intrinsic electroluminescence, in which a luminescent body is excited by local movement of electrons and holes within a luminescent layer, and emits light only in an alternating electric field; and (2) a carrier injection type electroluminescent device that excites a luminescent material by injecting electrons and holes from an electrode and recombining them within a light emitting layer, and operates in a DC electric field.

[0003] Intrinsic electroluminescence type light emitting devices (1) generally use an inorganic compound such as ZnS with Mn, Cu, etc. added as a light emitting body, but require a high alternating current electric field of 200 V or more for driving. However, it has problems such as high manufacturing cost and insufficient brightness and durability. The carrier injection type electroluminescent device (2) has become capable of achieving high luminance since thin film-like organic compounds have been used as the light emitting layer. For example, JP-A-59-194
No. 393, U.S. Patent No. 4,539,507,
JP-A-63-295695, U.S. Patent No. 4,720
, 432 and JP-A-63-264692 disclose electroluminescent devices comprising an anode, an organic hole-injecting transport band, an organic electron-injecting luminescent material, and a cathode. Typical examples of the materials include aromatic tertiary amine as an organic hole injecting and transporting material, and aluminum trisoxine as an organic electron-injecting light-emitting material.

[0004] Also, Jpn. Journal of
Applied Physics, Vol. 27, p.
713-715 includes an anode, an organic hole transport layer, a light emitting layer,
Electroluminescent devices consisting of an organic electron transport layer and a cathode have been reported, and the materials used in these devices include N,N'-diphenyl-N,N'- as an organic hole transport material.
Bis(3-methylphenyl)-1,1'-biphenyl-
Examples include 4,4'-diamine, 3,4,9,10-perylenetetracarboxylic acid bisbenzimidazole as an organic electron transport material, and phthaloperinone as a luminescent material. These examples demonstrate that in order to use organic compounds as hole-transporting materials, luminescent materials, and electron-transporting materials, it is necessary to explore various properties of these organic compounds and effectively combine these properties to create electroluminescent devices. In other words, it shows that research and development of a wide range of organic compounds is necessary.

Furthermore, research on carrier injection electroluminescent devices using organic compounds as light emitters, including the examples mentioned above, has a short history, and it cannot be said that sufficient research into materials and device development has been carried out. . Currently, there are many issues to be solved, such as further improvement in brightness, diversification of emission wavelengths so that the emission hues of blue, green, and red can be precisely selected when considering support for full-color displays, and improvement of durability. The reality is that

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned state of the prior art, and its purpose is to provide an electroluminescent device that has high luminance, exhibits various luminous hues, and is highly durable. The goal is to provide the following.

[0007]

[Means for Solving the Problems] In order to solve the above object, the present inventors studied the light emitting characteristics of an electroluminescent device and its layer structure, and confirmed the following facts. (1) In an electroluminescent device, recombination of holes and electrons injected from an electrode mainly occurs near the interface between the charge transport layer and the light emitting layer. (2) Luminous efficiency can be improved by localizing holes and electrons in specific locations within the device.

Based on this fact, the present inventors further investigated and found that an electroluminescent device that satisfies ease of manufacture, low driving voltage, high luminous efficiency, durability, etc., is based on its layer structure. It has been found that the present invention has the configurations shown in claims 1 to 6.

[0009] The invention will be explained in order starting from claim 1 below. The organic thin film electroluminescent device according to claim 1 is an organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer is a layer containing a hole transporting luminescent material. It is characterized by comprising a layer in which a hole-transporting luminescent material and an electron-transporting material coexist.

Next, the electroluminescent device according to claim 1 will be explained with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an electroluminescent device according to a first aspect of the invention. In the figure, 1 is a substrate, 2 is an anode, 3a is a layer containing a hole-transporting luminescent material, 3b is a layer in which a hole-transporting luminescent material and an electron-transporting material coexist, and 4
is the cathode.

[0011] As the substrate 1, a glass plate or a synthetic resin sheet is usually used, and it is desirable that the substrate be transparent to the light emitted from the light emitting layer. The material for forming the anode 2 is as follows:
Nickel, gold, platinum, palladium and alloys thereof, tin oxide (SnO2), indium tin oxide (ITO),
Metals with large work functions such as copper iodide, alloys and compounds thereof, and conductive polymers such as poly(3-methylthiophene) and polypyrrole can be used. On the other hand, as the material for forming the cathode 4, silver, tin, lead, magnesium, manganese, aluminum, or an alloy thereof, which has a small work function, is used. It is desirable that at least one of the materials used for the anode 2 and the cathode 4 be sufficiently transparent in the emission wavelength region of the device. Specifically 8
It is desirable to have a light transmittance of 0% or more.

As the hole-transporting luminescent material, any compound having fluorescence and excellent hole-transporting properties can be used. Compounds preferably used in the present invention are illustrated in Table 1 below. [Representative examples of hole-transporting luminescent materials]

[Table 1]

As the electron-transporting material, any compound exhibiting electron-transporting properties such as perylene derivatives and oxadiazole derivatives can be used. Compounds preferably used in the present invention are illustrated in Table 2 below. [Representative examples of electron transporting materials]

[Table 2]

In addition to the electron-transporting materials shown in Table 2, electron-transporting luminescent materials shown in Table 3 below can also be used. [Representative examples of electron-transporting luminescent materials]

[Table 3]

[0015] In the electroluminescent device according to claim 1, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting luminescent material and electron-transporting material contained in each layer may be the same or different compounds. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention of claim 1, the organic compound layer includes a layer 3a containing a hole-transporting luminescent material;
Layer 3 in which hole-transporting luminescent material and electron-transporting material coexist
In this case, the organic compound layer may be a layer in which an electron transporting material is added to a hole transporting luminescent material, and a layer containing an electron transporting material.

[0017] The element according to claim 1 having such a configuration,
When compared with a conventional device consisting of an anode, a hole-transporting light-emitting layer, an electron-transporting layer, and a cathode, there are the following differences. That is, in the conventional element, as described above, holes and electrons injected from the electrode are recombined only near the interface between the layer 3a and the layer 3b to emit light.
In the device having the above configuration, recombination occurs throughout the coexistence layer 3b, and light is emitted. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

Next, the electroluminescent device according to claim 2 will be described.

The electroluminescent device according to claim 2 is an organic thin film type electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer is a layer containing a hole transporting material. , is characterized by comprising a layer in which a hole-transporting material and an electron-transporting light-emitting material coexist.

The electroluminescent device according to claim 2 will be explained below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an electroluminescent device according to a second aspect of the invention. In the figure, 1 is the substrate, 2 is the anode,
3c is a layer containing a hole-transporting material, 3d is a layer in which a hole-transporting material and an electron-transporting light-emitting material coexist, and 4 is a cathode.

The substrate 1, anode 2 and cathode 4 are made of the same materials as those of the first aspect of the invention.

[0022] Also, as a hole transporting material, it has good film forming properties,
Any compound can be used as long as it has excellent hole transport properties. Examples of such compounds include compounds shown in Table 4, and hole-transporting light-emitting materials shown in Table 1 can also be used.

[Representative examples of hole-transporting materials]

[Table 4]

In the electroluminescent device according to claim 2, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting material and electron-transporting luminescent material contained in each layer may be the same or different compounds. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention of claim 2, the organic compound layer is composed of the layer 3c containing the hole transporting material and the layer 3d containing the hole transporting material and the electron transporting luminescent material. However, in this case, the organic compound layer may be a layer in which a hole-transporting material and an electron-transporting luminescent material coexist, and a layer containing an electron-transporting luminescent material.

[0026] The element according to claim 2 having such a configuration,
When compared with a conventional device consisting of an anode, a hole transporting layer, an electron transporting light emitting layer, and a cathode, there are the following differences. In other words, in conventional devices, holes and electrons injected from the electrode recombine only near the interface between the hole transporting layer and the electron transporting light emitting layer to emit light, as described above. In the device having the structure according to the invention in item 2, the coexistence layer 3
Recombination occurs throughout d, and light is emitted. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

Next, the invention of claim 3 will be described. The electroluminescent device according to claim 3 is an organic thin film electroluminescent device composed of a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material and a hole transporting material. It is characterized by comprising a layer in which a hole-transporting material and an electron-transporting luminescent material coexist, and a layer containing an electron-transporting luminescent material.

The electroluminescent device according to claim 3 will be explained below with reference to the drawings. FIG. 3 is a schematic cross-sectional view of an electroluminescent device according to the third aspect of the invention. In the figure, 1 is a substrate, 2 is an anode, 3e is a layer containing a hole-transporting material, 3f is a layer in which a hole-transporting material and an electron-transporting luminescent material coexist, and 3g is a layer containing an electron-transporting luminescent material. , and 4 are cathodes.

For the substrate 1, anode 2 and cathode 4, the same materials as described in the first aspect of the invention are used.

As the hole-transporting material, any compound can be used as long as it has good film-forming properties and is excellent in hole-transporting properties, but preferably those shown in Table 4 can be used.

[0031] As the hole-transporting luminescent material, any compound can be used as long as it has fluorescence in addition to film-forming properties and hole-transporting properties. A pore-transporting luminescent material is used.

[0032] As an electron transporting material, it has excellent film forming properties,
Any compound can be used as long as it exhibits electron transport properties. Examples of such electron-transporting materials include the compounds shown in Table 2.

Further, as the electron-transporting luminescent material, compounds shown in Table 3 are used, for example.

In the electroluminescent device according to claim 3, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting material, hole-transporting luminescent material, electron-transporting material, and electron-transporting luminescent material contained in each layer may be the same or different compounds. good. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention according to claim 3, the organic compound layer includes a layer 3e containing a hole-transporting material, a layer 3f in which a hole-transporting material and an electron-transporting luminescent material coexist,
and a layer 3g containing an electron-transporting luminescent material, where the organic compound layer includes a layer containing a hole-transporting luminescent material, and a hole-transporting luminescent material and an electron-transporting material coexisting. It may be composed of a layer containing an electron-transporting material and a layer containing an electron-transporting material.

[0036] The element according to claim 3 having such a configuration,
Compared to a conventional device consisting of an anode, a hole transporting layer, an electron transporting light emitting layer, and a cathode, or a conventional device consisting of an anode, a hole transporting light emitting layer, an electron transporting layer, and a cathode, There is a difference.

That is, in the conventional device, as described above, holes and electrons injected from the electrodes are deposited near the interface between the hole transporting layer and the electron transporting light emitting layer, or between the hole transporting light emitting layer and the electron transporting layer. In contrast, in the element configured according to the present invention, recombination occurs throughout the entire coexistence layer 3f and light emission occurs. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

Next, the invention of claim 4 will be described.

[0039] The invention according to claim 4 is an organic thin film type electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material; It is characterized by comprising a layer containing a luminescent material and a layer in which a luminescent material and an electron transporting material coexist.

The electroluminescent device according to claim 4 will be explained below with reference to the drawings. FIG. 4 is a schematic cross-sectional view of an electroluminescent device according to a fourth aspect of the invention. In the figure, 1 is a substrate, 2 is an anode, 3h is a layer containing a hole-transporting material, 3i is a layer containing a luminescent material, 3j is a layer in which a luminescent material and an electron-transporting material coexist, and 4 is a cathode. be.

As the substrate 1, anode 2, and cathode 4, those similar to those of the first aspect of the invention are used.

As the hole-transporting material, any compound can be used as long as it has good film-forming properties and has excellent hole-transporting properties, but preferably the same compounds as shown in Table 4 are used. Ru.

As the luminescent material, the compounds shown in Tables 1 and 3, for example, which have excellent film-forming properties and have fluorescence, are used.

The compounds shown in Table 1 can be used as hole-transporting materials, and the compounds shown in Table 3 can also be used as electron-transporting materials.

As the electron-transporting material, any compound can be used as long as it has excellent film-forming properties and exhibits electron-transporting properties, but the compounds shown in Table 2 are preferably used.

In the electroluminescent device according to claim 4, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting material, luminescent material, or electron-transporting material contained in each layer may be the same or different compounds. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention of claim 4, the organic compound layer includes a layer 3h containing a hole-transporting material, a layer 3i containing a luminescent material, and a layer 3i containing a luminescent material and an electron-transporting material. The organic compound layer is composed of a layer in which a hole-transporting material coexists, a layer containing a luminescent material, and a layer containing an electron-transporting material. I don't mind.

[0048] The element according to claim 4 having such a configuration,
When compared with a conventional device consisting of an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode, there are the following differences.

In other words, in conventional devices, as described above, holes and electrons injected from the electrodes recombine only near the interface between the hole transport layer and the light emitting layer, or between the light emitting layer and the electron transport layer, and emit light. In contrast, in the device configured according to the present invention, recombination occurs throughout the coexistence layer 3j,
Light emission occurs. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

Next, the invention of claim 5 will be described.

[0051] The invention according to claim 5 is an organic thin film type electroluminescent device composed of a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material; It is characterized by comprising a layer in which a luminescent material and an electron transporting material coexist.

The electroluminescent device according to claim 5 will be explained below with reference to the drawings. FIG. 5 is a schematic cross-sectional view of an electroluminescent device according to the fifth aspect of the invention. In the figure, 1 is a substrate, 2 is an anode, 3k is a layer containing a hole-transporting material, 3l is a layer in which a luminescent material and an electron-transporting material coexist, and 4 is a cathode.

As the substrate 1, anode 2, and cathode 4, those similar to those of the invention according to claim 1 are used.

As the hole-transporting material, any compound can be used as long as it has good film-forming properties and has excellent hole-transporting properties, but preferably the same compounds as shown in Table 4 are used. Ru.

As the luminescent material, the compounds shown in Tables 1 and 3, for example, which have excellent film-forming properties and have fluorescence, are used. Among the above compounds, those listed in Table 1 can be used as hole-transporting materials, and those listed in Table 3 can also be used as electron-transporting materials.

[0056] As an electron transporting material, it has excellent film forming properties,
Any compound that exhibits electron transport properties can be used, but preferably the compounds shown in Table 2 are used.

In the electroluminescent device according to claim 5, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting material, luminescent material, or electron-transporting material contained in each layer may be the same or different compounds. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention of claim 5, the organic compound layer is composed of the layer 3k containing a hole transporting material and the layer 3l containing a luminescent material and an electron transporting material. However, the organic compound layer may be composed of a layer in which a hole-transporting material and a luminescent material coexist, and a layer containing an electron-transporting luminescent material.

The element according to claim 5 having such a configuration,
Compared to a conventional device consisting of an anode, a hole transporting layer, a light emitting layer, an electron transport layer, and a cathode, or a conventional device consisting of an anode, a hole transporting light emitting layer, an electron transport layer, and a cathode, There is a difference.

In other words, in conventional devices, as described above, holes and electrons injected from the electrodes recombine and emit light only near the interface between the hole transport layer and the light emitting layer, or between the light emitting layer and the electron transport layer. In contrast, in the device configured according to the present invention, recombination occurs throughout the coexistence layer 3l,
Light emission occurs. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

Next, the invention of claim 6 will be described.

[0062] The invention according to claim 6 is an organic thin film type electroluminescent device composed of a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material; It is characterized by comprising a layer containing a luminescent material and a layer in which a luminescent material and an electron transporting material coexist.

The electroluminescent device according to claim 6 will be described below with reference to the drawings. FIG. 6 is a schematic cross-sectional view of an electroluminescent device according to a sixth aspect of the invention. In the figure, 1 is the substrate, 2 is the anode, 3m is a layer containing a hole-transporting material, 3n is a layer containing a luminescent material, 3o is a layer in which a luminescent material and an electron-transporting material coexist, 3p is an electron-transporting material. The layer containing the material, and 4 is the cathode.

As the substrate 1, anode 2, and cathode 4, those similar to those of the first aspect of the invention are used.

As the hole-transporting material, any compound can be used as long as it has good film-forming properties and has excellent hole-transporting properties, but it is preferable to use the same compounds as shown in Table 4. preferable.

[0066] As the luminescent material, compounds having excellent film-forming properties and fluorescence are used, and those shown in Tables 1 and 3 are preferably used. In this case, the compounds shown in Table 1 are used as hole-transporting materials, and the compounds shown in Table 3 are also used as electron-transporting materials.

[0067] As the electron-transporting material, any compound can be used as long as it has excellent film-forming properties and exhibits electron-transporting properties, but those listed in Table 2 are preferably used.

In the electroluminescent device according to claim 6, an anode is provided on a substrate by sputtering or the like, and a thin layer of the above-mentioned compound alone or in coexistence with other compounds is formed on the anode by vacuum evaporation or spin. It is produced by coating sequentially by a wet film forming method such as a coating method, and then providing a cathode thereon by an appropriate means. In this case, the hole-transporting material, luminescent material, or electron-transporting material contained in each layer may be the same or different compounds. Moreover, a plurality of similar compounds may be included in the same layer. When forming a layer consisting of a plurality of compounds, in the case of vacuum evaporation, a multi-component evaporation method is used in which each compound is evaporated at the same time, or if the compounds have close melting points, they may be evaporated in a sufficiently mixed state in advance. In the case of a wet film forming method, a mixed solution of each compound is used for coating. Further, a protective layer may be provided on the cathode 4 if necessary.

As described above, in the invention of claim 6, the organic compound layer includes a layer 3m containing a hole transporting material, a layer 3n containing a luminescent material, and a layer 3n containing a luminescent material and an electron transporting material. The organic compound layer is composed of a layer 3o that coexists with a layer 3p containing an electron-transporting material, and a layer 3p containing a hole-transporting luminescent material, a hole-transporting material, and a luminescent material. The organic compound layer may be a layer containing a hole-transporting material, a layer containing a luminescent material, and a layer containing an electron-transporting luminescent material. A layer containing a luminescent material, a layer containing a luminescent material, a layer containing a luminescent material and an electron-transporting material, and a layer containing an electron-transporting material may be used.

[0070] The element according to claim 6 having such a configuration,
When compared with a conventional device consisting of an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode, there are the following differences.

In other words, in conventional devices, as described above, holes and electrons injected from the electrodes recombine and emit light only near the interface between the hole transport layer and the light emitting layer, or the light emitting layer and the electron transport layer. In contrast, in the device having the configuration according to the sixth aspect, recombination occurs throughout the coexistence layer 3o, and light emission occurs. As a result, the number of light-emitting sites increases significantly compared to the conventional method, and improvements in luminance and luminous efficiency are realized.

[0072]

[Examples] The present invention will be further explained below with reference to Examples.

Example 1 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
A hole-transporting luminescent layer made of a hole-transporting luminescent material (compound No. 3 in Table 1) and having a thickness of 750 Å was formed by vacuum deposition. Next, Compound No. of Table 1 above. 3 and an electron-transporting material (compound No. 1 in Table 2) were co-deposited at approximately the same deposition rate (approximately 2 Å/sec) to form a co-existence layer of the hole-transporting luminescent material and the electron-transporting material at approximately It was formed to a thickness of 250 Å. Finally, a cathode made of aluminum having a thickness of about 1000 Å was similarly formed by vacuum evaporation to produce a device as shown in FIG. 1 (device A). The degree of vacuum during deposition is approximately 5.0 x 10
−6 Torr, and the substrate temperature is room temperature. For comparison, Compound No. 1 in Table 1 above was used. A hole-transporting light-emitting layer consisting of Compound No. 3 in Table 2; A device was fabricated under exactly the same conditions as above, except that electron transport layers each consisting of P1 were laminated to a thickness of about 500 Å (device P1). Connect a DC power source to the anode and cathode of these elements via lead wires,
When driven, when a voltage of 24 V was applied to element P1, a current with a current density of 87.1 mA/cm2 flowed.
Blue light emission with a brightness of 529 cd/m2 was observed. The maximum luminous efficiency of this device was 0.26 lm/W. On the other hand, in element A, the brightness is approximately 2.1 times higher at the same current density.
Furthermore, the maximum luminous efficiency was improved by about 1.4 times. Furthermore, no change was observed in the color tone of the emitted light.

Example 2 On a glass plate with an anode made of indium tin oxide (ITO) having a size of 3 mm x 3 mm and a thickness of 1000 Å,
Compound No. in Table 1 above. 3 and Compound No. 3 in Table 2. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec),
A coexistence layer of a hole-transporting luminescent material and an electron-transporting material was formed to a thickness of about 250 Å. Next, Compound No. 2 in Compound Table 2 above. An electron transport layer of 750 Å thick made of 1 and a cathode of about 1000 Å made of aluminum were also formed by vacuum evaporation to produce a device (device B). The degree of vacuum during vapor deposition was approximately 5.0×10 −6 Torr, and the substrate temperature was room temperature. When element B was connected to a DC power source and driven in the same manner as in Example 1, the luminance at the same current density was approximately 20.0 times higher than that of Comparative Example P1, and the maximum luminous efficiency was approximately 1.2 times higher. did. Furthermore, no change was observed in the color tone of the emitted light.

Example 3 On a glass plate on which an anode made of indium tin oxide (ITO) with a size of 3 mm x 3 mm and a thickness of 1000 Å was formed,
Compound No. in Table 4 above. A hole transport layer of 750 Å thick was formed by vacuum evaporation. Next, Compound No. of Table 4 above. 1 and compound No. 1 in Table 3. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec) to form a co-existence layer of a hole transporting material and an electron transporting light emitting material to a thickness of approximately 250 Å. Finally, a cathode made of aluminum about 10
00 Å was also formed by vacuum evaporation to produce a device as shown in FIG. 1 (device C). The degree of vacuum during deposition was approximately 5.
0×10 6 Torr, and the substrate temperature was room temperature. For comparison, Compound No. 4 in Table 4 above was used. A hole transport layer consisting of Compound No. 1 in Table 3; A device was fabricated under exactly the same conditions as above, except that the electron-transporting light-emitting layers each consisting of 1 were laminated to a thickness of about 500 Å (device P2). When a DC power supply was connected to the anode and cathode of these elements via lead wires and they were driven, when a voltage of 34V was applied to element P2, a current with a current density of 201 mA/cm2 flowed, and a yellow color with a brightness of 1940 cd/m2 was generated. Green light emission was observed. The maximum luminous efficiency of this device was 0.36 lm/W. On the other hand, in element C, the brightness is about 1 at the same current density.
．． The maximum luminous efficiency was improved by 3 times, and the maximum luminous efficiency was improved by about 1.2 times. No change was observed in the color tone of the emitted light.

Example 4 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound NO. of Table 4 above. 1 and compound No. 1 in Table 3. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec),
A coexistence layer of a hole-transporting material and an electron-transporting light-emitting material was formed to a thickness of about 250 Å. Next, compound No. of Table 3 above
．． An electron transporting light emitting layer having a thickness of 750 Å made of 1 and a cathode having a thickness of about 1000 Å made of aluminum were similarly formed by vacuum evaporation to produce a device (device D). The degree of vacuum during vapor deposition was approximately 5.0×10 −6 Torr, and the substrate temperature was room temperature. When element D was connected to a DC power source and driven in the same manner as in Example 1, the luminance at the same current density was approximately 1.4 times higher than that of Comparative Example P2, and the maximum luminous efficiency was approximately 1.2 times higher. did. Furthermore, no change was observed in the color tone of the emitted light.

Example 5 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound No. in Table 4 above. A hole transport layer of 500 Å thick was formed by vacuum evaporation. Next, Compound No. of Table 4 above. 1 and compound No. 1 in Table 3. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec) to form a coexistence layer of a hole transporting material and an electron transporting luminescent material to a thickness of approximately 50 Å. Furthermore, compound No. 3 of Table 3 above was added. An electron-transporting light-emitting layer of about 500 Å made of 1 and finally a cathode of about 1000 Å made of aluminum were formed by vacuum evaporation to produce a device as shown in FIG. 3 (device E). The degree of vacuum during vapor deposition was approximately 5.0×10 −6 Torr, and the substrate temperature was room temperature. For comparison, Compound No. 4 in Table 4 above was used. 1
and a hole transport layer consisting of Compound No. in Table 3. A device was fabricated under exactly the same conditions as above, except that the electron-transporting light-emitting layers each consisting of 1 were laminated to a thickness of about 500 Å (device P3). When a DC power supply was connected to the anode and cathode of these elements via lead wires and driven, the element P
3, the current density is 201mA when a voltage of 34V is applied.
A current of /cm2 was passed, and yellow-green light emission with a brightness of 1940 cd/m2 was observed. The maximum luminous efficiency of this element is 0.
It was 36 lm/W. On the other hand, in element E, the brightness is approximately 1.4 times higher at the same current density, and the maximum luminous efficiency is approximately 1.
Improved by 3 times. No change was observed in the color tone of the emitted light.

Example 6 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound No. in Table 1 above. A hole-transporting light-emitting layer having a thickness of 500 Å was formed by vacuum evaporation. Next, Compound No. of Table 1 above. 3 and Compound No. 3 in Table 2. 1 was co-evaporated at approximately the same deposition rate (approximately 2 Å/sec), and a co-evaporation layer of a hole-transporting luminescent material and an electron-transporting material was formed at a thickness of approximately 50 Å.
It was formed to a thickness of . Furthermore, compound No. of Table 2 above is added.
．． An electron-transporting light-emitting layer of about 500 Å made of aluminum and finally a cathode of about 1000 Å made of aluminum were also formed by vacuum evaporation to produce a device (device F). The degree of vacuum during vapor deposition was approximately 5.0×10 −6 Torr, and the substrate temperature was room temperature. For comparison, Compound No. 1 in Table 1 above was used. A hole-transporting light-emitting layer consisting of Compound No. 3 in Table 2; A device was produced under exactly the same conditions as above, except that the electron transporting layers each consisting of P1 were laminated to a thickness of about 500 Å (device P4). When a DC power supply was connected to the anode and cathode of these elements via lead wires and the elements were driven, 2
Current density 87.1mA/cm when applying a voltage of 4V
2 current flowed, and blue light emission with a brightness of 529 cd/m2 was observed. The maximum luminous efficiency of this element is 0.26lm/
It was W. On the other hand, in element F, the luminance was improved by about 2.7 times and the maximum luminous efficiency was improved by about 1.8 times at the same current density. No change was observed in the color tone of the emitted light.

Example 7 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound No. in Table 4 above. A hole transport layer of 500 Å thick was formed by vacuum evaporation. Next, Compound No. of Table 3 above. A light-emitting layer consisting of 1 was formed to a thickness of about 50 Å. Furthermore, compound No. 1 in Table 4 above was added. 1 and Table 2
Compound No. 1 at approximately the same deposition rate (approximately 2 Å/s
ec) to form a layer of 500 Å in which a luminescent material and an electron transporting material coexist. Finally, a cathode of approximately 1000 Å made of aluminum is formed by vacuum evaporation,
A device as shown in FIG. 4 was manufactured (device G). The degree of vacuum during vapor deposition was approximately 5.0×10 −6 Torr, and the substrate temperature was room temperature. For comparison, Compound No. 4 in Table 4 above was used. A hole transport layer of 500 Å consisting of Compound No. 1 in Table 3; A light-emitting layer of about 50 Å consisting of Compound No. 1 in Table 2, A device was fabricated under exactly the same conditions as described above, except that about 500 Å of electron transporting layer consisting of 1 was sequentially laminated (device P5). When a DC power supply was connected to the anode and cathode of these elements via lead wires and they were driven, a current with a current density of 186 mA/cm2 flowed in element G when a voltage of 25 V was applied.
Yellow-green light emission with a brightness of 2360 cd/m2 was observed. The maximum luminous efficiency of this device was 0.42 lm/W. On the other hand, in element P5, the brightness is about 1.0 at the same current density.
The maximum luminous efficiency was improved by 3 times, and the maximum luminous efficiency was improved by about 1.2 times. No change was observed in the color tone of the emitted light.

Example 8 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound NO. of Table 4 above. 1 and compound No. 1 in Table 3. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec),
The coexistence layer of the hole transporting material and the luminescent material is approximately 500 Å thick.
It was formed to a thickness of . Next, Compound No. of Table 3 above. A 50 Å thick light-emitting layer made of 1 was also formed by vacuum evaporation. Furthermore, compound No. 2 of Table 2 above was added. An electron transport layer of about 500 Å made of aluminum and finally a cathode of about 1000 Å made of aluminum were also formed by vacuum evaporation to produce a device (device H). The degree of vacuum during evaporation is approximately 5.0 x 10-
6 Torr, and the substrate temperature was room temperature. Example 1 of element H
When connected to a DC power source and driven in the same way as, Comparative Example P
At the same current density, the luminance was improved by about 1.4 times, and the maximum luminous efficiency was improved by about 1.3 times compared to that of No. 5. Furthermore, no change was observed in the color tone of the emitted light.

Example 9 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound No. in Table 1 above. A hole transport layer of 500 Å thick was formed by vacuum evaporation. Next, Compound No. of Table 3 above. Compound No. 1 and Table 2 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec) to form a layer of 500 Å in which a luminescent material and an electron transporting material coexist. Finally, a cathode made of aluminum having a thickness of about 1000 Å was similarly formed by vacuum evaporation to produce a device as shown in FIG. 5 (device I). The degree of vacuum during vapor deposition is approximately 5.0 x 10-6 To
rr, the substrate temperature is room temperature. For comparison, Compound No. 1 in Table 1 above was used. A hole transport layer of 500 Å consisting of Compound No. 3 in Table 3; A light-emitting layer of about 50 Å consisting of Compound No. 1 in Table 2, A device was fabricated under exactly the same conditions as above, except that an electron transporting layer of about 500 Å consisting of P1 was sequentially laminated (device P6). When a DC power supply was connected to the anode and cathode of these elements via lead wires and driven, element P6
Then, when a voltage of 31V is applied, the current density is 159mA/
A current of cm2 was passed, and yellow-green light emission with a brightness of 1216 cd/m2 was observed. The maximum luminous efficiency of this element is 0.2
It was 1 lm/W. On the other hand, in Element I, the brightness is about 1.5 times higher at the same current density, and the maximum luminous efficiency is about 1.3.
improved twice. Further, no change was observed in the color tone of the emitted light.

Example 10 On a glass plate on which an anode made of indium tin oxide (ITO) was formed, the size was 3 mm x 3 mm and the thickness was 1000 Å.
Compound No. in Table 1 above. 3 and Compound No. 3 in Table 3. 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec),
The coexistence layer of the hole transporting material and the luminescent material is approximately 500 Å thick.
It was formed to a thickness of . Next, Compound No. of Table 2 above. An electron transport layer of about 500 Å made of aluminum and finally a cathode of about 1000 Å made of aluminum were also formed by vacuum evaporation to produce a device (device J). The degree of vacuum during vapor deposition is approximately 5.0×
The temperature of the substrate was 10 −6 Torr and room temperature. When element J was connected to a DC power source and driven in the same manner as in Example 1, the luminance at the same current density was approximately 1.4 times that of Comparative Example P6.
Furthermore, the maximum luminous efficiency was improved by about 1.2 times. No change was observed in the color tone of the emitted light.

Example 11 On a glass plate on which an anode made of indium tin oxide (ITO) with a size of 3 mm x 3 mm and a thickness of 1000 Å was formed,
Compound No. in Table 1 above. A hole transport layer of 500 Å thick was formed by vacuum evaporation. Next, Compound No. of Table 3 above. A light-emitting layer consisting of 1 was formed to a thickness of about 50 Å. Next, Compound No. of Table 3 above. Compound No. 1 and Table 2 1 was codeposited at approximately the same deposition rate (approximately 2 Å/sec) to form a layer of approximately 50 Å in which the luminescent material and the electron transporting material coexist. Furthermore, compound N of Table 2 above is added.
o. An electron transport layer consisting of 1 was formed to a thickness of about 500 Å. Finally, a cathode made of aluminum having a thickness of about 1000 Å was similarly formed by vacuum evaporation to produce a device as shown in FIG. 6 (device K). The degree of vacuum during evaporation is approximately 5.0 x 10-
6 Torr, and the substrate temperature was room temperature. For comparison, Compound No. 1 in Table 1 above was used. A hole transport layer of 500 Å consisting of Compound No. 3 in Table 3; 1, and Table 2
Compound No. A device was fabricated under exactly the same conditions as above, except that an electron transport layer of about 500 Å consisting of P1 was sequentially laminated (device P7). When a DC power supply was connected to the anode and cathode of these elements via lead wires and they were driven, the current density of element P7 was 159 when a voltage of 31V was applied.
A current of mA/cm2 flowed, and yellow-green light emission with a brightness of 1216 cd/m2 was observed. The maximum luminous efficiency of this device was 0.21 lm/W. On the other hand, in element K, the luminance was improved by about 1.4 times and the maximum luminous efficiency was improved by about 1.3 times at the same current density. No change was observed in the color tone of the emitted light.

Example 12 On a glass plate with an anode made of indium tin oxide (ITO) having a size of 3 mm x 3 mm and a thickness of 1000 Å,
Compound No. in Table 1 above. A hole transport layer of about 500 Å thick was formed by vacuum deposition. Next, Compound No. of Table 1 above. 3 and Compound No. 3 in Table 3. 1 was co-evaporated at approximately the same deposition rate (approximately 2 Å/sec) to form a co-existing layer of a hole transporting material and a luminescent material to a thickness of approximately 50 Å. Next, Compound No. of Table 3 above. 1, thickness approximately 5
A 0 Å light emitting layer was also formed by vacuum evaporation. Furthermore, compound No. 2 of Table 2 above was added. an electron transport layer of about 500 Å made of aluminum, and finally a cathode of about 1000 Å made of aluminum.
.ANG. was similarly formed by vacuum evaporation to produce a device (device L). The degree of vacuum during vapor deposition is approximately 5.0 x 10-6 Torr
, the substrate temperature is room temperature. When element L was connected to a DC power source and driven in the same manner as in Example 1, the luminance at the same current density was approximately 1.8 times higher than that of Comparative Example P7, and the maximum luminous efficiency was approximately 1.5 times higher. did. No change was observed in the color tone of the emitted light.

Example 13 On a glass plate with an anode made of indium tin oxide (ITO) having a size of 3 mm x 3 mm and a thickness of 1000 Å,
Compound No. in Table 1 above. A hole transport layer of about 500 Å thick was formed by vacuum deposition. Next, Compound No. of Table 1 above. 3 and Compound No. 3 in Table 3. 1 was co-evaporated at approximately the same deposition rate (approximately 2 Å/sec) to form a co-existence layer of a hole-transporting material and a luminescent material to a thickness of approximately 50 Å. Next, Compound No. of Table 3 above. 1, thickness approximately 5
A 0 Å light emitting layer was also formed by vacuum evaporation. Next, Compound No. of Table 3 above. Compound No. 1 and Table 2 1,
Co-evaporation was performed at approximately the same deposition rate (approximately 2 Å/sec) to form a coexisting layer of a luminescent material and an electron transporting material to a thickness of approximately 50 Å. Furthermore, compound No. 2 of Table 2 above was added. An electron transport layer of about 500 Å made of aluminum, and finally a cathode of about 1000 Å made of aluminum, were also formed by vacuum evaporation.
A device was produced (device M). The degree of vacuum during deposition is approximately 5.0
×10 −6 Torr, and the substrate temperature was room temperature. When element M was connected to a DC power source and driven in the same manner as in Example 1,
Compared to Comparative Example P7, the luminance at the same current density was improved by about 2.2 times, and the maximum luminous efficiency was improved by about 1.9 times. No change was observed in the color tone of the emitted light.

[0086]

[Effects of the Invention] Since the organic thin film type electroluminescent device of the present invention has the above-described structure, it has the following effects. (1) The probability of recombination of holes and electrons injected from the electrode is increased, and luminance of light emission can be improved. (2) Since the heat generation of the element can be suppressed by improving the conversion efficiency into light energy, it is possible to reduce the deterioration of the organic compound layer due to temperature rise and to extend the life of the electroluminescent element. (3) By providing a layer in which different compounds coexist,
Crystallization of individual materials is suppressed, making it possible to maintain stable luminescent properties over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an organic thin film type electroluminescent device according to claim 1.

FIG. 2 is a schematic cross-sectional view of an organic thin film type electroluminescent device according to claim 2.

FIG. 3 is a schematic cross-sectional view of an organic thin film type electroluminescent device according to claim 3.

FIG. 4 is a schematic cross-sectional view of an organic thin film type electroluminescent device according to claim 4.

FIG. 5 is a schematic cross-sectional view of an organic thin film type electroluminescent device according to claim 5.

FIG. 6 is a schematic cross-sectional view of an organic thin film electroluminescent device according to claim 6.

[Explanation of symbols]

1: Substrate 2: Anode 3a: Layer containing a hole-transporting luminescent material 3b: Layer where a hole-transporting luminescent material and an electron-transporting material coexist 3c: Layer containing a hole-transporting material 3d: Hole-transporting material Layer 3e in which a material and an electron-transporting luminescent material coexist: Layer 3f containing a hole-transporting material: Layer 3g in which a hole-transporting material and an electron-transporting luminescent material coexist: Layer 3h containing an electron-transporting luminescent material : Layer 3i containing a hole transporting material: Layer 3j containing a luminescent material: Layer 3k in which a luminescent material and an electron transporting material coexist
: Layer 3l containing a hole transporting material: Layer 3m containing a luminescent material and an electron transporting material
: Layer 3n containing a hole transporting material: Layer 3o containing a luminescent material: Layer 3p in which a luminescent material and an electron transporting material coexist
: Layer 4 containing electron transporting material: Cathode

Claims (6)

[Claims] 1. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole-transporting luminescent material and a hole-transporting luminescent material. An organic thin film electroluminescent device comprising a layer in which a light emitting material and an electron transporting material coexist. 2. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer comprises a layer containing a hole transporting material and a hole transporting material. 1. An organic thin film electroluminescent device comprising a layer in which an electron-transporting luminescent material and an electron-transporting luminescent material coexist. 3. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer comprises a layer containing a hole transporting material and a hole transporting material. 1. An organic thin film electroluminescent device comprising: a layer in which an electron-transporting luminescent material coexists with an electron-transporting luminescent material; and a layer containing an electron-transporting luminescent material. 4. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material and a luminescent material. 1. An organic thin film electroluminescent device comprising a layer and a layer in which a luminescent material and an electron transporting material coexist. 5. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material, a luminescent material and an electron transporting material. An organic thin film type electroluminescent device characterized by comprising a layer in which a transporting material coexists. 6. An organic thin film electroluminescent device comprising a plurality of organic compound layers sandwiched between an anode and a cathode, wherein the organic compound layer includes a layer containing a hole transporting material and a luminescent material. 1. An organic thin film electroluminescent device comprising a layer, a layer in which a luminescent material and an electron transporting material coexist, and a layer containing an electron transporting material.