JP2000243572A - Organic electroluminescence element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroluminescence element capable of suppressing generation of cross talk without efficiency and enhancing high temperature storage stability. SOLUTION: The organic electroluminescence element is formed by stacking an anode layer 12, an inorganic compound-containing layer 14, an organic light emitting layer 16, and a cathode layer 18 in order on a transparent glass substrate 10, and an inorganic compound 14a is insularly scattered in the inorganic compound-containing layer 14. Therefore, the inorganic compound-containing layer has anisotropic conductivity having lower conductivity in the plane direction than that in the stacking direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device utilizing electroluminescence (hereinafter, also referred to as "EL device"). More specifically, the present invention relates to an organic EL device suitable for use in consumer and industrial display devices (displays) or light sources of printer heads.

[0002]

2. Description of the Related Art An electroluminescent element has characteristics such as high visibility because it emits light by itself and excellent impact resistance because it is completely solid. Therefore, EL
The element is expected to be used as a light emitting element in various display devices.

[0003] Such organic EL elements include an inorganic EL element using an inorganic compound as a light emitting material and an organic EL element using an organic compound as a light emitting material. Of these, organic E
Since the applied voltage of the L element can be significantly lower than that of the inorganic EL element, research on its practical use as a next-generation display element has been actively conducted.

[0004] An organic EL element has an organic light-emitting layer and a pair of electrode layers sandwiching the organic light-emitting layer. That is,
The basic configuration is that an anode layer, an organic light emitting layer, and an anode layer are sequentially laminated. This is schematically represented as “anode / organic light emitting layer / cathode”.

A structure in which a hole injection / transport layer or an electron injection / transport layer is inserted into this basic structure, for example, “anode layer / hole injection / transport layer / organic light emitting layer / cathode layer”, “anode / organic light emitting layer” The composition of “/ electron injection / transport layer / cathode layer” or “anode layer / hole injection / transport layer / organic light emitting layer / electron injection / transport layer / cathode layer” is known.

The hole injecting and transporting layer has a function of transporting holes injected from the anode layer to the organic light emitting layer. For this reason, if this hole injection / transport layer is interposed between the organic light emitting layer and the anode layer, many holes can be injected into the organic light emitting layer with a lower electric field. In addition, since the hole injection transport layer does not transport electrons, electrons injected into the organic light emitting layer from the cathode layer side are accumulated at the interface between the hole injection transport layer and the organic light emitting layer. Therefore, the luminous efficiency is improved by providing the hole injection transport layer.

An example of the prior art using an inorganic semiconductor film exhibiting hole conductivity as such a hole injection transport layer is disclosed in Japanese Patent Publication No. 266428. According to the technique disclosed in this publication, a P-type semiconductor layer having a thickness of, for example, 10 to 100 nm is formed as an inorganic semiconductor film by plasma CV.
It is formed by the D method.

[0008]

When the anode of the organic electroluminescence element has a minute protrusion or edge, an electric field concentrates on the minute protrusion or edge, and a leak current is generated.
Then, when crosstalk occurs between pixels of the element due to a leak current, a displayed image is blurred and image quality is deteriorated.

Therefore, in order to reduce the leak current, a measure for eliminating the fine protrusions and the like by polishing the anode surface is considered. However, when the polishing is performed, polishing scratches may be generated and the leak current may increase.

In order to reduce the leak current, a film having a high amorphous property is formed on the anode,
It is also conceivable to take measures to cover the smile protrusions on the anode. However, in this case, providing a film with low conductivity on the anode surface causes another problem that the efficiency of hole injection from the anode to the organic light emitting layer is reduced. On the other hand, if a highly conductive film such as a semiconductor is provided on the surface of the anode, the leakage current in the lateral direction increases, which may cause crosstalk.

Further, when light is extracted to the anode side,
When a film having low light transmittance is provided between the organic light emitting layer and the anode layer, there is a problem that the luminous efficiency of the organic EL element is reduced.

By the way, in order to put the organic EL device into practical use, various durability is required. In particular, in consideration of usage in outdoor and on-vehicle use, the organic EL element is required to have driving stability and storage stability in a high-temperature environment, for example, high-temperature storage stability of 75 ° C.

However, when the conventional organic EL device is stored at a high temperature of about 75 ° C., there have been problems in that the emission color changes and the luminous efficiency decreases. The cause of these problems is that, since the anode and the organic light emitting layer of the inorganic compound having different coefficients of thermal expansion are laminated, the adhesion between the layers at high temperature is reduced. In addition,
These problems have been improved by using organic materials having higher durability than before, but they have not been a fundamental solution.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to suppress the occurrence of crosstalk without lowering the luminous efficiency and to attain high-temperature storage stability in an electroluminescent device. The purpose is to provide.

[0015]

In order to achieve this object, according to the organic EL device of the present invention, an anode layer, an inorganic compound-containing layer, an organic light emitting layer and a cathode layer are sequentially laminated. The inorganic compound-containing layer has a lower conductivity in a direction (plane direction) along the surface than in a direction perpendicular to the surface of the organic light-emitting layer (stacking direction). Is provided.

Here, the inorganic compound-containing layer means a thin film layer in which the inorganic compound is unevenly distributed. Therefore,
It may be a heterogeneous layer composed of only an inorganic compound or a heterogeneous layer composed of an inorganic compound and an organic compound. Here, the anisotropic conductivity means that the conductivity in the stacking direction is larger than the conductivity in a direction perpendicular to the stacking direction (plane direction).

The conductivity σ1 in the laminating direction and the conductivity σ2 in the plane direction of the inorganic compound-containing layer can be measured, for example, as follows. That is, when measuring the conductivity σ1 in the stacking direction, two electrode layers may be provided with the inorganic compound-containing layer interposed therebetween, and the conductivity may be measured between the two electrode layers. When measuring the conductivity σ2 in the plane direction, two electrodes spaced apart from each other in the plane direction may be provided in the inorganic compound layer, and the conductivity may be measured between the two electrodes. The relationship between the conductivity σ1 of the inorganic compound-containing layer in the stacking direction and the conductivity σ2 of the plane direction is “σ1> 10
σ2 ”is sufficient, but“ σ1> 10
0σ2 ”is more desirable.

As described above, according to the organic EL device of the present invention, since the inorganic compound-containing layer has anisotropic conductivity, the leakage current is suppressed from flowing in the plane direction while ensuring the conductivity in the stacking direction. can do. Thus, the occurrence of crosstalk can be suppressed without lowering the hole injection efficiency.

Further, as a material for the inorganic compound-containing layer,
By employing a material having a coefficient of thermal expansion closer to the coefficient of thermal expansion of the anode layer, it is possible to greatly improve the high-temperature storage stability of the organic EL element.

According to the second aspect of the present invention, the inorganic compound-containing layer has a structure in which the inorganic compound is distributed in an island shape.

With this configuration, the hole injection efficiency is ensured through the portions of each island, but the conductivity between the islands separated from each other is low, so that the generation of the leak current in the plane direction is suppressed. can do. Thus, the occurrence of crosstalk can be suppressed without lowering the hole injection efficiency.

Further, in a region between the islands, an anode layer,
The layer immediately above the inorganic compound-containing layer (for example, an organic light emitting layer) can be directly adhered. For this reason, the adhesion of the anode layer can be improved.

According to the third aspect of the present invention, the thickness of the inorganic compound-containing layer is set to a value within a range of 1 nm to 5 nm.

With such a structure, the inorganic compound is practically distributed in an island shape in the inorganic compound-containing layer formed on the anode by, for example, vapor deposition.

According to the fourth aspect of the present invention, the inorganic compound-containing layer is constituted by columnar polycrystals grown in a direction perpendicular to the surface of the organic compound layer.

With such a configuration, the columnar polycrystal is
In the growth direction, that is, in this case, the conductivity in the lamination direction is high,
In the non-growth direction, that is, in this case, the conductivity in the plane direction is low. Therefore, the occurrence of crosstalk can be suppressed without lowering the hole injection efficiency.

Further, according to the method for manufacturing an organic EL device according to the fifth aspect of the present invention, an organic electroluminescent device having a structure in which an anode layer, an inorganic compound-containing layer, an organic light emitting layer and a cathode layer are sequentially laminated. Upon production, an inorganic compound-containing layer is formed on the anode layer, and the inorganic compound-containing layer is deposited in such an amount that the thickness of the inorganic compound-containing layer falls within the range of 1 nm to 5 nm. There is a way to end.

As described above, according to the present invention, an organic EL device in which an inorganic compound is distributed in an island shape in an inorganic compound-containing layer can be easily manufactured.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. The drawings to be referred to are
The size, shape and arrangement of each component are only schematically shown to the extent that the present invention can be understood. Therefore, the present invention is not limited only to the illustrated example. In the drawings, hatching representing a cross section may be omitted.

[First Embodiment] In the first embodiment, FIG.
An example in which the inorganic compound-containing layer has an island shape will be described with reference to FIG. The organic EL device 100 according to the first embodiment has a structure in which an anode layer 12, an inorganic compound-containing layer 14, an organic light emitting layer 16 and a cathode layer 18 are sequentially stacked on a transparent glass substrate 10. The inorganic compound-containing layer 14 is composed of an inorganic compound 14a distributed in an island shape and an organic compound 14b filled between the inorganic compounds 14a.

Here, the inorganic compound-containing layer 14 and the method of forming the same, which are features of the present invention, will be described first. As a material of the inorganic compound 14a constituting the inorganic compound-containing layer 14, for example, microcrystal Si, Si
Of C, oxide, nitride, semiconductor, metal, and insulator,
What forms an island-like lump when forming a thin film is preferable. For example, chalcogenides or nitrides of Ge, Sn, Zn and Cd are more preferable. These inorganic compounds have a small absorption coefficient, particularly low quenching properties, and are excellent in transparency. Therefore, if these inorganic compounds are used,
A large amount of light can be extracted to the outside via the inorganic compound-containing layer 14.

Further, chalcogenides of Ge, Sn, Zn and Cd include, for example, SiO, SiO ₂ , GeO, Gd.
An oxide such as eO ₂ , SnO ₂ , PbO, In ₂ O ₃ , GaO, or CdO is preferable.

As a material of the organic compound 14b constituting the inorganic compound-containing layer 14, for example, the organic light emitting layer 1
The same material as that of 6 may be used, or another hole transport material may be used if necessary.

Since the thickness of the inorganic compound-containing layer 14 is as thin as 1 nm to 5 nm, the inorganic compound is distributed between the anode layer 12 and the organic light emitting layer 16 in an island shape. For this reason, the inorganic compound-containing layer 14 has an anisotropic conductivity that is lower in conductivity in a direction (plane direction) along the surface than in a direction perpendicular to the surface of the organic light emitting layer 16 (stacking direction). Have. Here, the island shape means the inorganic compound-containing layer 14.
Inside, the material lump of the inorganic compound is formed discontinuously on the anode layer 12, which means that each material lump does not cover the surface of the anode layer 12.

As described above, since the inorganic compound is distributed in the form of islands in the inorganic compound-containing layer 14, when the inorganic compound is made of a metal, a semiconductor, or the like and has high conductivity, the inorganic compound is positively passed through the inorganic compound. While the hole injection efficiency is ensured, the conductivity between the islands separated from each other is low, so that it is possible to suppress the generation of the leak current in the planar direction.

When the inorganic compound 14a is made of an insulator or the like and has low conductivity, the inorganic compound-containing layer 14
Is determined by the organic compound 14b. That is, in the stacking direction, since the anode layer 12 and the organic light emitting layer 16 are directly connected via the organic compound 14b, high conductivity can be ensured. On the other hand, in the plane direction, a material such as an island-shaped insulator is used. Since the lumps are scattered, the conductivity is lower than in the stacking direction. Thereby, this organic EL
According to the element, the occurrence of crosstalk can be suppressed without lowering the hole injection efficiency.

Further, in the region between the islands, the anode layer 1
2 and the organic light emitting layer 16 immediately above the inorganic compound containing layer 14 can be directly adhered. Therefore, the adhesion of the anode layer 12 can be improved.

In forming the inorganic compound-containing layer 14, any suitable method such as a sputtering method, a vapor deposition method, a spin coating method, a casting method, and an LB (Langmuir-Blodgett) method may be employed. it can.

When the inorganic compound-containing layer 14 is deposited by, for example, a vacuum evaporation method, the inorganic compound 1 is deposited on the anode layer.
What is necessary is just to form a film so that 4a is distributed in an island shape. Also, in the case where a film is formed on a material on which an inorganic compound is likely to be uniformly deposited, the film formation may be terminated when the inorganic compound 14a is deposited in such an amount that its thickness falls within a range of 1 nm to 5 nm. The inorganic compound 14a is practically deposited in an island shape. Further, after depositing the inorganic compound 14a, the organic compound 1
As 4b, the inorganic compound-containing layer 14 is formed by depositing an organic light emitting material or an organic hole injecting and transporting material as required by a vacuum evaporation method.

Next, each layer other than the inorganic compound-containing layer 14 will be described. First, the anode layer 12 will be described.
As a material of the anode layer 12, it is preferable to use a metal, an alloy, an electrically conductive compound, or a mixture thereof having a large work function (for example, 4.0 eV or more). As a specific material, for example, indium tin oxide (IT
O), indium zinc oxide (In-Zn-O)
(Also referred to as “IXO”), copper iodide, indium oxide, tin oxide, zinc oxide, gold, platinum, palladium and the like can be used alone or in combination of two or more.

The thickness of the anode layer 12 can be any suitable thickness, for example, 10 nm to 1000 nm.
It is desirable to set the value in the range of nm to 10 to 200
More preferably, the value is in the range of nm. Further, the anode layer is substantially transparent, more specifically, has a light transmittance of 10% or more so that light emitted from the organic light emitting layer can be effectively extracted to the outside through the anode layer. Is preferable.

Next, the organic light emitting layer 16 will be described.
The organic light emitting material used as a constituent material of the organic light emitting layer 16 preferably has the following three functions (a) to (c). (A) Charge injection function: a function of injecting holes from an anode or a hole injection layer while applying an electric field, while injecting electrons from a cathode layer or an electron injection layer. (B) Transport function: a function of moving injected holes and electrons by the force of an electric field. (C) Light-emitting function: a function of providing a field for recombination of electrons and holes and connecting them to light emission.

However, it is not always necessary to have all of the above-mentioned functions (a) to (c). Some organic light emitting materials are suitable. Therefore, any material can be suitably used as long as the transfer of electrons in the organic light emitting layer is promoted and recombination with holes near the center of the organic light emitting layer. As such a material, for example, the organic light emitting layer 16 includes an 8-quinolinol aluminum complex (hereinafter, abbreviated as “Alq”).
Is mentioned.

In forming the organic light emitting layer 14, any suitable method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, and a sputtering method can be adopted. For example, when forming by a vacuum evaporation method, the evaporation temperature is 50 to 450 ° C., and the degree of vacuum is 1 × 10 ^−3.
It is desirable to set the conditions to be Pa or less, a film formation rate of 0.01 to 50 nm / sec, and a substrate temperature of −50 to 300 ° C.

The organic light emitting layer can also be formed by dissolving the organic light emitting material in a solvent to form a solution, and then thinning the solution by spin coating or the like.

The organic light emitting layer is formed by appropriately selecting a method and conditions for forming the organic light emitting layer and solidifying it from a thin film formed by depositing a material compound in a gaseous state or a material compound in a solution state or a liquid phase state. It is preferable to use a molecular deposition film which is a film formed by the above method. Usually, this molecular deposition film can be distinguished from a thin film (molecule accumulation film) formed by the LB method by a difference in an aggregated structure or a higher-order structure and a functional difference caused by the difference.

The thickness of the organic light emitting layer can be appropriately selected depending on the situation, but is preferably, for example, a value within a range of 5 nm to 5 μm. The reason for this is that if the thickness of the organic light emitting layer is less than 5 nm, the emission luminance and durability may decrease, while the thickness of the organic light emitting layer is 5 μm.
This is because if the value exceeds, the value of the applied voltage may increase.

As the material of the cathode layer 18, it is desirable to use a metal, an alloy, an electrically conductive compound or a mixture thereof having a small work function (for example, less than 4.0 eV). Such materials include, for example, Mg, A
One kind such as l, In, Li, Na, Cs, and Ag can be used alone or in combination of two or more kinds.

Further, as a material of the cathode layer 18, Ag,
High melting point metals such as Al, Cr, Mo, Ta, ITO,
ZnO-Al, or a transparent conductive oxide such as _{SnO 2 -Sb, Cr 2 O 3} , Pr 2 O 5, NiO, MnO 2, Mn 2 O 5
A colored or black conductive oxide such as a conductive oxide may be used.

When light is extracted from the cathode layer 18 side, it is desirable to use a transparent material for the cathode layer 18. On the other hand, when light is extracted from the anode layer 12 side, a colored or black non-transparent material may be used for the cathode layer 18.

The thickness of the cathode layer 18 can be any suitable thickness, for example, 10 nm to 2000 n.
m is preferably in the range of 10 to 1000
More preferably, the value is in the range of nm.

Further, although not shown in FIG. 1, a sealing layer for preventing intrusion of moisture or oxygen into the organic EL device may be provided so as to cover the entire device. Preferred materials for the sealing layer include a copolymer obtained by copolymerizing tetrafluoroethylene and a monomer mixture containing at least one comonomer; a fluorinated copolymer having a cyclic structure in the copolymer main chain; Polyethylene, polypropylene, polymethacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene or a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene; an absorbent material having an absorption rate of 1% or more An absorption rate of 0.1
% Or less of a moisture-proof substance; In, Sn, Pb, Au, Cu,
Metals such as Ag, Al, Ti, Ni; MgO, SiO, S
iO ₂ , GeO, NiO, CaO, BaO, Fe ₂ O, Y
Metal oxides such as ₂ O ₃ and TiO ₂ ; MgF ₂ , LiF, Al
Metal fluorides such as F ₃ and CaF ₂ ; liquid fluorinated carbon such as perfluoroalkane, perfluoroamine, and perfluoropolyether; and a composition in which an adsorbent that adsorbs moisture and oxygen is dispersed in the liquid fluorinated carbon. Objects and the like.

In forming the sealing layer, a vacuum evaporation method, a spin coating method, a sputtering method, a casting method, an MBE (molecular beam epitaxy) method, a cluster ion beam evaporation method, an ion plating method, a plasma polymerization method ( RF excitation super-ion plating method), reactive sputtering method, plasma CVD method, laser CVD
Method, thermal CVD method, gas source CVD method, or the like can be appropriately employed.

[Second Embodiment] In a second embodiment, an example will be described in which the inorganic compound-containing layer has a columnar polycrystalline structure of an inorganic compound grown in the laminating direction. According to the organic EL element 102 of the second embodiment, a transparent glass substrate 10
The anode layer 12, the inorganic compound containing layer 20, the organic light emitting layer 1
6 and a cathode layer 18 are sequentially laminated. In this embodiment, since the configuration other than the inorganic compound-containing layer 20 is the same as the configuration in the above-described first embodiment, a detailed description thereof will be omitted.

Then, the organic EL device 10 of the second embodiment
In No. 2, a ZnSe layer having a thickness of 20 nm is formed on the inorganic compound-containing layer 20 by vacuum evaporation. This ZnS
The e layer has a columnar polycrystalline structure grown in the film forming direction upon film formation. For this reason, in this ZnSe layer, the conductivity in the stacking direction (growth direction) is high, but the conductivity in the planar direction is low due to the crystal grain boundaries. Therefore,
In the organic EL element 102, occurrence of crosstalk can be suppressed without lowering the hole injection efficiency. Further, it is desirable that the pitch of the crystal grain boundaries be equal to or less than the pitch of the display pixels of the organic EL element panel.

[0056]

Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. (Example 1) In the example, 75 mm x 25 mm x
An ITO film having a thickness of 100 nm (manufactured by Geomatic) was used on a 1 mm glass substrate. Then, this ITO was patterned in a stripe shape with a width of 400 μm and a gap of 100 μm to form an anode layer.
Subsequently, the substrate with ITO was immersed in isopropyl alcohol and subjected to ultrasonic cleaning, and then washed with UV-300 (trade name) manufactured by Samco International Co., using both ultraviolet light and ozone.

In place of the substrate with ITO, ITO may be formed on a normal glass substrate by sputtering. In this case, the glass substrate is mounted on a commercially available sputtering apparatus (manufactured by Nidec Anelva, magnetron sputtering apparatus), and a commercially available ITO target (manufactured by Mitsui Kinzoku Co., Ltd.) is sputtered under the conditions of a sputtering potential of 280 V and a substrate temperature of 50 ° C. It is preferable to form an ITO film with a thickness of 100 nm.

Subsequently, CVD is performed on the substrate with ITO.
A 5 nm-thick SiC film was formed by a chemical vapor deposition method. Note that this thickness does not indicate that the SiC was formed in the form of a thin film.
This indicates that an amount equivalent to nm was attached.

Next, after mounting this substrate on a substrate holder provided in a vacuum chamber of a vacuum evaporation apparatus, the vacuum chamber was
The pressure was reduced to × 10 ⁻⁴ Pa. N, N'-di- (naphthyl-1-yl) -N, N'-diphenyl-4,4'-benzidine (hereinafter abbreviated as "NPD") is provided on each resistance heating boat of this vacuum evaporation apparatus. 200 mg each of 8-quinolinol aluminum complex (hereinafter abbreviated as “Alq”), and an Al—Li alloy (Li: 5 at%) in the resistance heating filament in advance. Was.

Next, the board containing the NPD was heated and NPD was deposited at a deposition rate of 1 to 2Å / sec to form an NPD layer having a thickness of 60 nm as an organic compound. Subsequently, in order to form an organic light emitting layer, the boat containing Alq is heated, Alq is deposited at a deposition rate of 1 to 3Å / sec, and the thickness is 60 nm.
Was formed. Finally, the filament containing the Al-Li alloy is heated and the Al-Li alloy is deposited at a deposition rate of 8 ° / sec.
An alloy was deposited to form a cathode layer having a thickness of 150 nm.

When the cross section of the organic EL device thus formed was observed with a transmission electron microscope, it was confirmed that the inorganic compound-containing layer had a fine particle-like structure having a particle size of about 10 nm to 100 nm. Was done.

The results of a light emission test performed by applying a DC voltage to the organic EL device are shown in Table 1 below. That is, the current density when a voltage of 6.5 V is applied is 3.
² mA / cm ² and the emission luminance was 105 cd / m ² (n
it), the efficiency L / J was 3.3 cd / A, and the luminous efficiency was 1.6 lm / W.

In the organic EL device of Example 1, on the display screen, only the selected pixel was turned on, the other non-selected pixels were not turned on, and no crosstalk was observed.
In Table 1 below, “○” indicates that no crosstalk was recognized, and “X” indicates that crosstalk was recognized.

As a heat-resistant storage test, the organic EL
When the device was stored at a temperature of 80 ° C. for 100 hours, no change was observed in the light emission characteristics. In Table 1 below, as a result of the heat-resistant storage test, no change was observed in the light-emitting characteristics, and “○” indicates that a change was observed in the light-emitting characteristics.

Therefore, as shown in Table 1 below, the organic EL device of Example 1 can suppress the occurrence of crosstalk without lowering the luminous efficiency, and
It was confirmed that it had high high-temperature storage stability.

[0066]

[Table 1]

Example 2 Next, in Example 2, instead of SiC, ZnSe having a thickness of 5 nm was formed in the form of islands by a vacuum deposition method as an inorganic compound of the inorganic compound-containing layer. In Example 2, the structure and forming method of the inorganic compound-containing layer other than the inorganic compound were the same as in Example 1.

Table 1 shows the results of a light emission test performed by applying a DC voltage to the organic EL device. That is, the current density when a voltage of 6.5 V is applied is 3.
² mA / cm ² and an emission luminance of 106 cd / m ² (n
it), the efficiency L / J was 3.3 cd / A, and the luminous efficiency was 1.6 lm / W, and the same performance as in Example 1 was obtained. In addition, no crosstalk was observed on the display screen.
No change was observed in the light emission characteristics.

Therefore, the organic EL device of Example 2 also
As in Example 1, it was confirmed that the occurrence of crosstalk could be suppressed without lowering the luminous efficiency, and that high storage stability at high temperatures was obtained.

Example 3 Next, in Example 3, as the inorganic compound of the inorganic compound-containing layer, 5 nm thick SiO ₂ was distributed in the form of islands by sputtering instead of SiC of Example 1. Formed. Note that in Example 3, the configuration and forming method of the inorganic compound-containing layer other than the inorganic compound were the same as in Example 1.

The results of a light emission test performed by applying a DC voltage to the organic EL device are shown in Table 1 above. That is, the current density when a voltage of 6.5 V is applied is 3.
3 mA / cm ² , and the emission luminance was 109 cd / m ² (n
it), the efficiency L / J was 3.3 cd / A, and the luminous efficiency was 1.6 lm / W, and the same performance as in Example 1 was obtained. In addition, no crosstalk was observed on the display screen.
No change was observed in the light emission characteristics.

Therefore, the organic EL device of Example 3 also
It was confirmed that the occurrence of crosstalk could be suppressed without lowering the luminous efficiency, and that it had high-temperature storage stability.

Example 4 Next, in Example 4, instead of SiC of Example 1, TiO ₂ having a thickness of 5 nm was distributed in the form of islands by sputtering as the inorganic compound in the inorganic compound-containing layer. Formed. In Example 2, the structure and forming method of the inorganic compound-containing layer other than the inorganic compound were the same as in Example 1.

The results of a light emission test performed by applying a DC voltage to the organic EL device are shown in Table 1 above. That is, the current density when a voltage of 6.5 V is applied is 3.
² mA / cm ² and the emission luminance was 105 cd / m ² (n
it), the efficiency L / J was 3.3 cd / A, and the luminous efficiency was 1.6 lm / W, and the same performance as in Example 1 was obtained. In addition, no crosstalk was observed on the display screen.
No change was observed in the light emission characteristics.

Therefore, the organic EL device of Example 4 also
It was confirmed that the occurrence of crosstalk could be suppressed without lowering the luminous efficiency, and that it had high-temperature storage stability.

Example 5 Next, in Example 5, an inorganic compound-containing layer was formed to a thickness of 20 nm and grown in the stacking direction.
It has a columnar polycrystalline structure (column shape) of nSe. In Example 5, the structure and forming method of the inorganic compound-containing layer other than the inorganic compound were the same as in Example 1.

Table 1 shows the results of a light emission test performed by applying a DC voltage to the organic EL device. That is, the current density when a voltage of 6.5 V is applied is 3.
3 mA / cm ² , and the emission luminance was 110 cd / m ² (n
it), the efficiency L / J was 3.3 cd / A, and the luminous efficiency was 1.6 lm / W, and the same performance as in Example 1 was obtained. In addition, no crosstalk was observed on the display screen.
No change was observed in the light emission characteristics.

Therefore, the organic EL device of Example 5 having the column-shaped inorganic compound-containing layer also has the same light emitting efficiency as the organic EL device of Example 1 having the island-shaped inorganic compound-containing layer without lowering the luminous efficiency. In addition, it was confirmed that the occurrence of crosstalk could be suppressed, and that the composition had high-temperature storage stability.

As described above, in each of the examples, high luminous efficiency is realized despite the provision of the inorganic compound-containing layer. This is presumably because the surface area of the inorganic compound was increased as a result of distributing the inorganic compound in the form of islands in the inorganic compound-containing layer, and the hole injection efficiency was improved. Further, since the luminous efficiency is improved, a desired luminous luminance can be obtained with a lower driving voltage.

(Comparative Example 1) Next, as Comparative Example 1, an organic EL device having no inorganic compound-containing layer was formed. In Comparative Example 1, the configuration was the same as that in Example 1 except that the inorganic compound-containing layer was omitted.

The results of a light emission test performed by applying a DC voltage to the organic EL device of Comparative Example 1 are shown in Table 1 above. That is, when a 7.0 V DC voltage is applied, the current density is 3.4 mA / cm ² and the emission luminance is 11
4 cd / m ² (nit), and the efficiency L / J is 3.4.
cd / A, and the luminous efficiency was 1.5 lm / W. Therefore, in the case of the comparative example, high emission luminance was obtained, but the luminous efficiency was poor, and it can be seen that the hole injection efficiency was lower than that of the example.

In the organic EL device of Comparative Example 1, no crosstalk due to a leak current was observed on the display screen. However, as a heat-resistant storage test, when the organic EL device was stored at a temperature of 80 ° C. for 100 hours, a change in light emission characteristics was recognized because a dark region was generated in a part of the light emitting surface. Therefore,
In the organic EL device of Comparative Example 1, it was found that there was a problem in the adhesion between the anode layer and the hole injection layer.

Comparative Example 2 Next, as Comparative Example 2, a uniform P-type low-resistance amorphous SiC layer having a thickness of 100 nm was formed instead of the inorganic compound-containing layer. In the comparative example, the conductivity of the amorphous SiC layer is in the same direction. Further, in Comparative Example 2, the configuration other than the amorphous SiC layer was the same as the configuration in Example 1 described above.

The results of a light emission test performed by applying a DC voltage to the organic EL device of Comparative Example 2 are shown in Table 1 above. That is, when a DC voltage of 6.5 V is applied, the current density is 3.3 mA / cm ² and the emission luminance is 11
0 cd / m ² (nit), and the efficiency L / J is 3.3.
cd / A, and the luminous efficiency was 1.6 lm / W. Therefore, in the case of the comparative example, the same luminous brightness and luminous efficiency as those of the examples were obtained.

However, in the organic EL device of Comparative Example 2, crosstalk due to leak current was observed on the display screen. Further, as a heat-resistant storage test, when the organic EL device was stored at a temperature of 80 ° C. for 100 hours, a change in light emission characteristics was recognized because a dark region was generated in a part of the light emission surface.

In the above-described embodiment, an example has been described in which the present invention is configured under specific conditions. However, the present invention can be variously modified. For example, in the above-described embodiment, a structure example in which only the anode layer, the inorganic compound-containing layer, the organic light emitting layer, and the cathode layer are sequentially laminated has been described, but the structure of the organic EL device of the present invention is not limited thereto. However, other layers may be inserted between these layers. For example, an electron injection / transport layer may be interposed between the organic light emitting layer and the cathode layer.

In the above-described embodiment, an example was described in which the inorganic compound-containing layer was provided in contact with the anode layer. However, in the present invention, the inorganic compound-containing layer may not necessarily be in contact with the anode layer. For example, the island portions of the inorganic compound-containing layer may be dispersed in another organic layer.

In the above-described embodiment, an example in which the inorganic compound-containing layer and the specific material are used has been described. In the present invention, any suitable material having hole conductivity is used as the inorganic compound-containing layer. be able to.

[0089]

As described above in detail, according to the organic EL device of the present invention, since the inorganic compound-containing layer has anisotropic conductivity, the leakage current can be reduced while ensuring the conductivity in the stacking direction. Flow in a plane direction can be suppressed.
Thus, the occurrence of crosstalk can be suppressed without lowering the hole injection efficiency.

When the inorganic compound-containing layer is distributed in an island shape, the anode layer and the layer immediately above the inorganic compound-containing layer can be directly adhered to each other in the region between the islands. For this reason, the adhesion of the anode layer can be improved.

Further, by adopting a material having a coefficient of thermal expansion closer to the coefficient of thermal expansion of the anode layer as the material of the inorganic compound-containing layer, it is possible to greatly improve the high-temperature storability of the organic EL element. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of an organic EL device according to a first embodiment.

FIG. 2 is a cross-sectional view illustrating a structure of an organic EL device according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Anode layer 14 Inorganic compound containing layer 14a Inorganic compound 14b Organic compound 16 Organic light emitting layer 18 Cathode layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB00 AB03 AB06 AB12 AB13 AB15 BB05 CA01 CB01 DA00 DA01 DB03 EA04 EB00 EC00 FA01 FA03

Claims (5)

[Claims] 1. A structure in which an anode layer, an inorganic compound-containing layer, an organic light-emitting layer, and a cathode layer are sequentially laminated, wherein the inorganic compound-containing layer has a higher conductivity than a direction perpendicular to the surface of the organic light-emitting layer. An organic electroluminescent element having low anisotropy in the direction along the surface. 2. The organic electroluminescence device according to claim 1, wherein the inorganic compound is distributed in an island shape in the inorganic compound-containing layer. 3. The thickness of the inorganic compound-containing layer is from 1 nm to
3. The organic electroluminescent device according to claim 2, wherein the value is within a range corresponding to 5 nm. 4. The organic electroluminescent device according to claim 1, wherein the inorganic compound-containing layer is made of columnar polycrystal grown in a direction perpendicular to the surface of the organic light emitting layer. 5. In producing an organic electroluminescence device having a structure in which an anode layer, an inorganic compound-containing layer, an organic light-emitting layer, and a cathode layer are sequentially laminated, an inorganic compound-containing layer is formed on the anode layer, and The method of manufacturing an organic electroluminescence device, wherein the film formation is terminated when the inorganic compound-containing layer is formed in an amount such that the thickness of the inorganic compound-containing layer falls within a range of 1 nm to 5 nm.