JP2000235893A - Organic electroluminescent element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability, to lower the driving voltage, and to raise the light emitting luminance by providing an inorganic thin film layer between a positive electrode layer and an organic light emitting layer and/or between a negative electrode layer and the organic light emitting layer, and giving the predetermined value to an intermediate level of the inorganic thin film layer for charge injection in response to the position of the inorganic thin film layer. SOLUTION: A positive electrode layer 10, an inorganic thin film layer 12, an organic light emitting layer 14 and a negative electrode layer 16 are laminated on a board in this order. In the case where the inorganic thin film layer 12 is provided between the positive electrode layer 10 and the organic light emitting layer 14, the intermediate level thereof is set at a value smaller than the ionizing potential of the organic light emitting layer 14, and in the case where the inorganic thin film layer 12 is provided between the negative electrode layer 16 and the organic light emitting layer 14, the intermediate level of the inorganic thin film layer 12 is set at a value larger than the electron affinity of the organic light emitting layer 14, and charge injection is performed through the intermediate level of the inorganic thin film layer 12. With this structure, charge injection is facilitated without utilizing the tunnel effect at the time of injecting charge. Consequently, driving voltage is lowered, light emitting luminance is raised, and durability is improved.

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 (hereinafter sometimes referred to as an organic EL device) and a method of manufacturing the same. More specifically, consumer and industrial display devices (displays)
Alternatively, the present invention relates to an organic EL device suitable for use as a light source of a printer head and a method for manufacturing the same.

[0002]

2. Description of the Related Art Organic EL devices having an organic light emitting layer sandwiched between electrodes have been intensively researched and developed for the following reasons. (1) Since it is a completely solid element, it is easy to handle and manufacture. (2) Since self light emission is possible, no light emitting member is required. (3) Since it is excellent in visibility, it is suitable for a display. (4) Easy full color printing. However, the organic light-emitting layer is an organic substance, and it is not easy to inject electrons from the cathode, and it is generally difficult to transport electrons and holes. The problem was seen.

[0003] Japanese Patent Application Laid-Open No. Hei 8-288809 discloses an organic EL device provided with an insulating thin film layer between an electrode and an organic light emitting layer in order to enable long-term use. Specifically, the organic EL device disclosed in this publication includes an insulating thin film layer made of aluminum nitride, tantalum nitride, or the like between an anode layer and an organic light emitting layer or between a cathode layer and an organic light emitting layer. Is provided.

Further, Japanese Patent Application Laid-Open No. 9-260063 discloses that
In order to provide a low-cost organic EL device without using m-MTDATA or a tetraaryldiamine derivative, NiO is provided between the electrode and the organic light emitting layer.
In ₂ O ₃ , ZnO, SnO ₂ or B, P, C, N,
An inorganic material layer to which at least one of O is added, or N
An organic EL device having an inorganic material layer made of i _1-x O (0.05 ≦ x ≦ 0.5) is disclosed.

[0005]

However, the organic EL device disclosed in JP-A-8-288069 is
Since aluminum nitride, tantalum nitride, or the like is used for the insulating thin film layer, the value of the ionization potential is too large, and as a result, there has been a problem that the driving voltage tends to be high. That is, the inorganic thin film layer made of these inorganic compounds is an electric insulating layer, and since the ionization energy is excessively large, holes are injected from the anode by a tunnel effect. Therefore, it was necessary to apply a high voltage between the electrodes of the organic EL element in order to obtain a predetermined light emission luminance.

The organic EL device disclosed in Japanese Patent Application Laid-Open No. 9-260063 is characterized in that NiO is used as a main component, and the selectivity of a material usable for an inorganic material layer is excessively limited. In addition, there is a problem that the luminous efficiency is low.

Therefore, the inventors of the present invention diligently studied the above problem, and found that even when an organic EL element was provided with an inorganic thin film layer, for example, the inorganic thin film layer was formed by combining a plurality of specific inorganic compounds. By configuring, it has been found that charges can be injected by forming an intermediate level in the inorganic thin film layer. That is, the present invention has a specific inorganic thin film layer, excellent durability, low driving voltage,
Moreover, it is an object of the present invention to provide an organic EL device having high emission luminance and a method for manufacturing an organic EL device capable of efficiently obtaining such an organic EL device.

[0008]

According to one aspect of the present invention, there is provided an organic EL device having at least an anode layer, an organic light emitting layer, and a cathode layer in order, wherein an inorganic thin film is provided between the anode layer and the organic light emitting layer. When a layer is provided, the intermediate level of the inorganic thin film layer is set to a value smaller than the ionization potential of the organic light emitting layer, and when the inorganic thin film layer is provided between the cathode layer and the organic light emitting layer, An organic EL, wherein the intermediate level of the inorganic thin film layer is set to a value larger than the electron affinity of the organic light emitting layer, and charge injection is performed through the intermediate level of the inorganic thin film layer.
Element. With this configuration, charge injection becomes easy without using a tunnel effect at the time of charge injection. Therefore, it is possible to obtain an organic EL device having a low driving voltage, high emission luminance, and excellent durability. The intermediate level in the inorganic thin film layer is defined as the valence band level of the inorganic thin film layer (ionization potential of an organic substance) and the conduction band level (electron affinity of an organic substance).
Energy level that exists between This intermediate level can be determined by measuring a fluorescence spectrum and electronic properties. And, when an organic layer other than the organic light emitting layer is provided between the inorganic thin film layer and the organic light emitting layer provided on the anode side, the intermediate level of the inorganic thin film layer is set. The value may be smaller than the ionization potential of the organic layer. In this case, the intermediate level of the inorganic thin film layer does not necessarily have to be smaller than the ionization potential of the organic light emitting layer. When an inorganic thin film layer is provided between the anode layer and the organic light emitting layer in order to more reliably form an intermediate level in the inorganic thin film layer, the energy level of the inorganic thin film layer is reduced by the work of the anode layer. The energy level between the function and the ionization potential of the organic light emitting layer. When an inorganic thin film layer is provided between the cathode layer and the organic light emitting layer, the work function of the cathode layer and the electron affinity of the organic light emitting layer are determined. More preferably, the energy level is between the two. As such an organic EL element, specifically, an organic EL element including an inorganic thin film layer containing at least one compound selected from the following group A and at least one inorganic compound selected from the group B is used. No. Group A: Si, Ge, Sn, Pb, Ga, In, Zn, C
d, Mg chalcogenides or nitrides thereof. Group B: compounds of Groups 5A to 8 of the periodic table. That is, by using the inorganic compound of Group A and the inorganic compound of Group B in this way, an inorganic thin film is obtained. An intermediate level can be reliably formed in the layer. Therefore, it is possible to inject electric charges at a low voltage via the intermediate level, and it is possible to obtain an organic EL device having excellent durability and high emission luminance. In addition, if the combination of the inorganic compound of Group A and the inorganic compound of Group B is used, transparency is not impaired.

In constructing the organic EL device of the present invention, the value of the band gap energy of the inorganic thin film layer is Ba, and the value of the band gap energy of the organic light emitting layer is B.
When h, it is preferable that the relationship of Ba> Bh is satisfied. With this configuration, the light transmittance is improved,
The amount of light that can be extracted outside (light extraction efficiency)
Can be more.

Further, in constituting the organic EL device of the present invention, the inorganic compound of Group A is composed of Si, Ge, Sn, Zn.
And Cd chalcogenides or nitrides thereof. Since these compounds can maintain the excited state particularly long among the inorganic compounds of Group A,
The extinction is reduced, and the amount of light that can be extracted outside can be increased.

In constituting the organic EL device of the present invention, the inorganic compound of Group B is composed of Ru, V, Mo, Re,
Pd and Ir oxides are preferred. By using these compounds, an intermediate level can be reliably formed in the inorganic thin film layer. In addition, these B
The inorganic thin film layer containing the group of inorganic compounds is preferably provided between the anode and the organic light emitting layer.

In constituting the organic EL device of the present invention, the total amount of the inorganic thin film layer is set to 100 at. %, The content of the inorganic compound of Group B is 0.1 to 50 at.
%. By setting the value in such a range, it is easier to adjust the ionization potential of the inorganic thin film layer while maintaining high transparency (light transmittance).

In constituting the organic EL device of the present invention, it is preferable that the thickness of the inorganic thin film layer is set to a value within a range of 1 to 100 nm. With such a configuration, it is possible to obtain an organic EL element that is more excellent in durability, has a low driving voltage, and has high emission luminance.
Further, if the film thickness is in such a range, the thickness of the organic EL element does not become excessively large.

In constituting the organic EL device of the present invention, the organic light emitting layer may contain at least one of styryl group-containing aromatic compounds represented by the following general formulas (1) to (3). preferable.

[0015]

Embedded image

[In the general formula (1), Ar ¹ has 6 carbon atoms.
To 40 aromatic groups, Ar ² , Ar ³ , and Ar ⁴
Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is 1 to 6 Is an integer. ]

[0017]

Embedded image

[In the general formula (2), Ar ⁵ has 6 carbon atoms.
An 40 aromatic group, Ar ⁶ and Ar ^7, hydrogen atom or carbon atoms each an aromatic group having 6 to 40,
At least one of Ar ⁵ , Ar ⁶ and Ar ⁷ is substituted with a styryl group, and the condensed number m is an integer of 1 to 6. ]

[0019]

Embedded image

[In the general formula (3), Ar ⁸ and Ar
¹⁴ is an aromatic group having 6 to 40 carbon atoms, and Ar ^{9 to} A
r ¹³ is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are It is 0 or 1, respectively. ]

Another aspect of the present invention is a method for manufacturing any one of the above-described organic EL devices, wherein the inorganic thin film layer is preferably formed by a sputtering method, and the organic light emitting layer is preferably formed by a vacuum evaporation method. . When formed in this manner, a dense inorganic thin film layer or organic light emitting layer having a uniform thickness can be formed. Therefore, it is possible to provide an organic EL element having more uniform light emission luminance.

[0022]

Embodiments of the present invention will be specifically described below with reference to the drawings. The drawings referred to merely schematically show the size, shape, and arrangement of each component so 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 First, a first embodiment of the organic EL device of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an organic EL device 100, which has a structure in which an anode layer 10, an inorganic thin film layer 12, an organic light emitting layer 14, and a cathode layer 16 are sequentially laminated on a substrate (not shown). Is represented. Hereinafter, the inorganic thin film layer 12 and the organic light emitting layer 14, which are characteristic portions of the first embodiment, will be mainly described. Therefore, the other components, for example, the configuration and manufacturing method of the anode layer 10 and the cathode layer 16 will be briefly described, and the portions not mentioned will be the configurations generally known in the field of organic EL devices. A manufacturing method can be adopted.

(1) Inorganic Thin Film Layer (Constituent Material) The inorganic thin film layer must contain a combination of the following inorganic compounds of Group A and Group B. Group A: Si, Ge, Sn, Pb, Ga, In, Zn, C
d, Mg chalcogenides or nitrides thereof Group B: compounds of Groups 5A to 8 of the periodic table The reason for this is that, as described above in part, by combining inorganic compounds of Group A and Group B, durability and It is possible to obtain an organic EL element which is excellent in transparency, has a low driving voltage, and has high light emission luminance.
Conversely, if only one of the inorganic compounds is used, it is difficult to form a so-called intermediate level in the inorganic thin film layer, so that the driving voltage is reduced or the durability is improved. This is because they cannot do it.

Here, specifically preferred inorganic compounds of Group A include SiO _x (1 ≦ x ≦ 2) and GeO _x (1 ≦ x ≦
2), SnO ₂ , PbO, In ₂ O ₃ , ZnO, GaO,
CdO, MgO, SiN, GaN, ZnS, ZnSe,
CdS, CdSe, ZnSSe, CaSSe, MgSS
e, GaInN and the like.

Further, among the inorganic compounds of Group A, Si, G
Preferably, chalcogenides of e, Sn, Zn, Cd and Mg or nitrides thereof are used. For this reason,
As described above in part, these inorganic compounds have a small absorption coefficient among the inorganic compounds of Group A, and particularly have a low quenching property and are excellent in transparency, so that the amount of light that can be extracted outside is increased. This is because Note that S
Among the chalcogenides of i, Ge, Sn, Zn, Cd and Mg, an oxide is particularly preferable.

Specific examples of inorganic compounds belonging to Group B include RuO _x , V ₂ O ₅ , MoO ₃ , Ir ₂ O ₃ , NiO ₂ ,
RhO ₄ , ReO _x , CrO ₃ , Cr ₂ O ₃ , RhO _x , Mo
O _x, include alone or in combinations of two or more such VO _x. Of these inorganic compounds of group B, Ru, R
oxides of e, V, Mo, Pd and Ir, ie R
uO _x , ReO _x , V ₂ O ₅ , MoO ₃ , MoO _x , Pd
O ₂ and Ir ₂ O ₃ are more preferable. The reason for this is that, as described above in part, by using these inorganic compounds of Group B, an intermediate level is more reliably formed in the inorganic thin film layer, and the charge injection is improved.

Next, the content of the inorganic compound of Group B will be described. When the content of the inorganic compound of Group B is adjusted to 100 at. %,
50 at. %. The reason is that the content of the inorganic compound of Group B is 0.1 at. %, The intermediate level may not be formed in the inorganic thin film layer. On the other hand, when the content of the inorganic compound of Group B is 50 at. %, The inorganic thin film layer is colored,
This is because transparency (light transmittance) may decrease.
Therefore, the balance between the ease of forming an intermediate level in the inorganic thin film layer and the transparency and the like becomes better, so that the total amount of the inorganic thin film layer is 100 at. %, The content of the inorganic compound in Group B is 1 to 30 at. %, More preferably within the range of 2 to 20 at. %
It is more preferable to set the value within the range. When the inorganic thin film layer is composed of the inorganic compounds of the groups A and B, the content of the inorganic compound of the group A is 10% of the total amount.
0 at. % Is the value obtained by subtracting the content of the inorganic compound of Group B from%. Therefore, the content of the inorganic compound of Group B is 0.1 to 50 at. %, The content of the inorganic compound in Group A is 50 to 99.9 at. %. However, when the inorganic thin film layer contains a compound (third component) other than the inorganic compounds of Group A and Group B,
It is preferable to determine the content of the inorganic compound of Group A in consideration of the content of the third component.

(Film Thickness) The thickness of the inorganic thin film layer is not particularly limited.
It is preferable that the value be in the range of nm. The reason for this is that when the thickness of the inorganic thin film layer is less than 0.5 nm, a pinhole is generated and a leakage current may be observed when the inorganic thin film layer is used for a long period of time. If the film thickness exceeds 100 nm, the driving voltage may increase or the light emission luminance may decrease. Therefore, since the balance between the durability and the value of the driving voltage and the like becomes better, the thickness of the inorganic thin film layer is more preferably set to a value in the range of 0.5 to 50 nm, and more preferably in the range of 0.5 to 5 nm. It is more preferable to set the value to

(Forming Method) Next, a method of forming an inorganic thin film layer will be described. Although such a forming method is not particularly limited, for example, a method such as a sputtering method, a vapor deposition method, a spin coating method, a casting method, and an LB method can be employed. In particular, a high-frequency magnetron sputtering method can be employed. preferable. Specifically, in an inert gas, the degree of vacuum is 1 × 10 ⁻⁷ to 1 × 10 ⁻³ Pa, and the film formation rate is 0.1 mm.
It is preferable to perform sputtering under the conditions of 01 to 50 nm / sec and the substrate temperature of -50 to 300 ° C.

(Light Emitting Mechanism) Next, a light emitting mechanism in the case where an inorganic thin film layer composed of an inorganic compound of Group A and Group B is provided will be described. In a conventional organic EL device, AlN,
As described above, there is an example in which an inorganic thin film layer made of TaN or the like is provided, and there is a problem that a high driving voltage is required because of utilizing a tunnel effect. Therefore, in the present invention, a so-called intermediate level is provided in the inorganic thin film layer, and low voltage driving and high light emission luminance are enabled by using the intermediate level. More specifically,
By composing the inorganic thin film layer from the inorganic compounds of Group A and Group B, the energy level of the inorganic thin film layer can be adjusted between the work function of the electrode layer (anode layer, cathode layer) and the electron affinity of the organic light emitting layer. This is a value, and charge is injected through an intermediate level formed thereby. Therefore, electric charges are easily injected into the organic light emitting layer, so that low voltage driving is possible and high light emission luminance is obtained. In addition, since low-voltage driving becomes possible, the durability of the organic EL element is significantly improved. The intermediate level in the inorganic thin film layer may exist inside the inorganic thin film layer, or may exist at an interface between the inorganic thin film layer and the organic light emitting layer. In addition, it is preferable that the energy level of the inorganic thin film layer is set smaller than the work function of the anode layer so that electrons do not pass through the organic light emitting layer. That is, by giving the inorganic thin film layer an electron barrier property, higher emission luminance can be obtained. For the same purpose, it is preferable that the energy level of the inorganic thin film layer is set higher than the work function of the cathode layer so that holes do not pass through the organic light emitting layer.

(2) Organic Light-Emitting Layer (Constituent Material) The organic light-emitting material used as a constituent material of the organic light-emitting layer preferably has the following three functions. (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 functions (a) to (c). For example, the organic light-emitting material may have a hole injection / transport property larger than an electron injection / transport property. 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.

Here, in order to improve the recombination property in the organic light emitting layer, the electron mobility of the organic light emitting material is set to 1 × 1
It is preferable to set the value to 0 ⁻⁷ cm ² / V · s or more. The reason is that when the value is less than 1 × 10 ⁻⁷ cm ² / V · s,
This is because high-speed response in the organic EL element becomes difficult or the light emission luminance may decrease. Therefore, the electron mobility of the organic light emitting material is 1.1 × 10 ⁻⁷ to 2 × 10
^-3 cm ² / V · s is more preferable, and a value within a range of 1.2 × 10 ^{−7 to} 1.0 × 10 ⁻³ cm ² / V · s is more preferable. More preferred.

Further, the electron mobility is restricted to be smaller than the hole mobility of the organic light emitting material in the organic light emitting layer. This is because the light emission luminance may be restricted and the light emission luminance may be reduced. On the other hand, the reason why the electron mobility of the organic light emitting material is limited to be larger than 1/1000 of the hole mobility is that when the electron mobility becomes excessively small,
This is because it becomes difficult to recombine with holes near the center of the organic light emitting layer, and the light emission luminance may also be reduced. Therefore, the hole mobility (μ _h ) and the electron mobility (μ _e ) of the organic light-emitting material in the organic light-emitting layer are expressed as μ _h / 2>
It is more preferable to satisfy the relationship of μ _e > μ _h / 500,
even more preferably satisfies the _{μ h / 3> μ e>} μ h / 100 relationship.

In the first embodiment, it is preferable to use an aromatic ring compound having a styryl group represented by the above-mentioned general formulas (1) to (3) for the organic light emitting layer. By using such an aromatic ring compound having a styryl group, the conditions of the electron mobility and the hole mobility of the organic light emitting material in the organic light emitting layer described above can be easily satisfied. Here, among the aromatic groups having 6 to 40 carbon atoms, preferred aryl groups having 5 to 40 nuclear atoms include phenyl, naphthyl, anthranyl, phenanthryl, pyrenyl, coronyl, biphenyl, terphenyl, pyrrolyl, furanyl, Thiophenyl, benzothiophenyl, oxadiazolyl, diphenylanthranyl, indolyl, carbazolyl, pyridyl, benzoquinolyl and the like. Further, the preferred number of nuclear atoms is 5 to 40.
Examples of the arylene group include phenylene, naphthylene, anthranylene, phenanthrylene, pyrenylene, colonylene, biphenylene, terphenylene, pyrrolylene,
Furanylene, thiophenylene, benzothiophenylene,
Oxadiazolylene, diphenylanthranylene, indolylene, carbazolylene, pyridylene, benzoquinolylene and the like can be mentioned.

The aromatic group having 6 to 40 carbon atoms may be further substituted by a substituent. Preferred examples of the substituent include an alkyl group having 1 to 6 carbon atoms (an ethyl group, a methyl group, an i- Propyl group, n-propyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group, etc., alkoxy group having 1 to 6 carbon atoms (ethoxy group, methoxy group, i-propoxy) Group, n-propoxy group, s-butoxy group, t-butoxy group, pentoxy group, hexyloxy group, cyclopentoxy group, cyclohexyloxy group, etc.), 5 to 40 nuclear atoms
An aryl group, an amino group substituted with an aryl group having 5 to 40 nuclear atoms, an ester group having an aryl group having 5 to 40 nuclear atoms, an ester group having an alkyl group having 1 to 6 carbon atoms, a cyano group, Examples include a nitro group and a halogen atom.

Further, a fluorescent brightener such as benzothiazole, benzimidazole or benzoxazole, or a metal complex having a styrylbenzene compound or an 8-quinolinol derivative as a ligand is used in combination in the organic light emitting layer. Is also preferred. Further, an organic light-emitting material having a distyrylarylene skeleton such as 4,4′-bis (2,2-diphenylvinyl) biphenyl) is used as a host, and the host is provided with a strong fluorescent dye ranging from blue to red, such as a coumarin-based or host. It is also preferable to use a fluorescent dye doped with the same fluorescent dye as described above.

(Forming Method) Next, a method of forming an organic light emitting layer will be described. Such a forming method is not particularly limited, and for example, a method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, and a sputtering method can be employed. For example, when the film is formed by a vacuum deposition method, the deposition temperature is 50 to 450 ° C., the degree of vacuum is 1 × 10 ⁻⁷ to 1 × 10 ⁻³ Pa in an inert gas, and the deposition rate is 0.01 to 50.
It is preferable to adopt a condition of nm / sec and a substrate temperature of −50 to 300 ° C. Alternatively, the organic light emitting layer can also be formed by dissolving the binder and the organic light emitting material in a solvent to form a solution, and then thinning the solution by spin coating or the like. Note that the organic light-emitting layer is formed by appropriately selecting a formation method and formation conditions, and forming a thin film formed by deposition from a material compound in a gaseous state, or solidifying from a material compound in a solution state or a liquid phase state. It is preferable to use a molecular deposition film as a film. 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.

(Thickness) The thickness of the organic light-emitting layer is not particularly limited and can be appropriately selected depending on the situation. Specifically, the thickness is preferably in the 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 if the thickness of the organic light emitting layer exceeds 5 μm, the value of the applied voltage increases. Because there is. Accordingly, since the balance with the emission luminance and the value of the applied voltage becomes better, the thickness of the organic light emitting layer is more preferably set to a value in the range of 10 nm to 3 μm, and more preferably to a value in the range of 20 nm to 1 μm. More preferably, it is set to a value.

(3) Electrode (Anode Layer) As the anode layer, 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). Specifically, one kind of indium tin oxide (ITO), indium copper, tin, zinc oxide, gold, platinum, palladium, carbon and the like can be used alone or in combination of two or more kinds. The thickness of the anode layer is not particularly limited, but is preferably in the range of 10 to 1000 nm, and more preferably in the range of 10 to 200 nm. Further, the anode layer is substantially transparent, and 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. Is preferred.

(Cathode Layer) On the other hand, for the cathode layer, it is preferable 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). Specifically, one of magnesium, aluminum, indium, lithium, sodium, cesium, silver and the like can be used alone or in combination of two or more. Also, the thickness of the cathode layer is not particularly limited, but is preferably in the range of 10 to 1000 nm, more preferably in the range of 10 to 200 nm.

(4) Others Although not shown in FIG. 1, it is preferable to provide a sealing layer for preventing moisture and oxygen from entering the organic EL element so as to cover the entire element. Preferred materials for the sealing layer include a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer; a fluorinated copolymer having a cyclic structure in the copolymer main chain. Polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene,
Polydichlorodifluoroethylene or a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene; a water-absorbing substance having an absorption of 1% or more; a moisture-proof substance having a water absorption of 0.1% or less; In, Sn, Pb, Au, Cu , Ag,
Metals such as Al, Ti, Ni; MgO, SiO, Si
O ₂ , GeO, NiO, CaO, BaO, Fe ₂ O, Y ₂
Metal oxides such as 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] Next, a second embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 3 is a cross-sectional view of an organic EL element 102 according to a second embodiment, in which an anode layer 10, an inorganic thin film layer 12, a hole transport layer 1
3, the organic light emitting layer 14 and the cathode layer 16 have a structure in which they are sequentially laminated on a substrate (not shown). By providing the hole transport layer 13 in this manner, a function of efficiently transporting the injected holes can be exhibited. Therefore, the provision of the hole transport layer 13 facilitates the movement of holes to the organic light emitting layer, and enables a high-speed response of the organic EL device.

The organic EL device 10 of the second embodiment
2 has the same structure as the organic EL device 100 of the first embodiment except that a hole transport layer 13 is inserted between the inorganic thin film layer 12 and the organic light emitting layer 14. ing. Therefore, the following description is about the hole transport layer 13 which is a characteristic part of the second embodiment,
Other components, for example, the organic light emitting layer 14 and the like, can have the same configuration as in the first embodiment.

(1) Constituent Material It is preferable that the hole transport layer is composed of an organic compound or an inorganic compound. Examples of such an organic material include a phthalocyanine compound, a diamine compound, a diamine-containing oligomer and a thiophene-containing oligomer. Preferred inorganic compounds include, for example, amorphous silicon (α-Si), α-Si
C, microcrystal silicon (μC-Si), μC
—SiC, II-VI compounds, III-V compounds, amorphous carbon, crystalline carbon, diamond and the like.

(2) Structure and Forming Method The hole transport layer is not limited to a single layer structure, but may have a two-layer structure or a three-layer structure. Furthermore, the thickness of the hole transport layer is not particularly limited, but is preferably, for example, a value in the range of 0.5 nm to 5 μm. The method for forming the hole transport layer is not particularly limited, but it is preferable to employ the same method as the method for forming the hole injection layer.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIG. FIG.
Is a cross-sectional view of the organic EL element 104 according to the third embodiment, which includes an anode layer 10, an inorganic thin film layer 12, and a hole transport layer 1.
3. Organic light emitting layer 14, electron injection layer 15, and cathode layer 16
Are sequentially laminated on a substrate (not shown). Thus, the electron injection layer 15
Is provided, a function of injecting electrons efficiently can be exhibited. Therefore, the provision of the electron injection layer 15 facilitates the movement of electrons to the organic light emitting layer 14 and enables the organic EL element to respond at high speed.

The organic EL device 104 according to the third embodiment is different from the organic EL device 104 according to the second embodiment except that an electron injection layer 15 is inserted between the organic light emitting layer 14 and the cathode layer 16. Has the same structure as the organic EL element 102 of FIG.
Therefore, the following description is about the electron injection layer 15 which is a characteristic portion of the third embodiment, and the other components are the same as those of the first and second embodiments or the organic components. A configuration generally known in the field of EL devices can be used.

(1) Constituent Material The electron injection layer is preferably made of an organic compound or an inorganic compound. However, by being composed of an inorganic compound, an organic EL device having more excellent electron injectability and durability from a cathode can be obtained. Here, preferred organic compounds include 8-hydroxyquinoline and oxadiazole, and derivatives thereof, for example, metal chelate oxinoid compounds containing 8-hydroxyquinoline.

It is preferable to use an insulator or a semiconductor as the inorganic compound constituting the electron injection layer.
If the electron injection layer is formed of an insulator or a semiconductor, current leakage can be effectively prevented, and electron injection properties can be improved. Such insulators are selected from the group consisting of alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides. Preferably, at least one metal compound is used. It is preferable that the electron injecting layer is composed of such an alkali metal chalcogenide in that the electron injecting property can be further improved.

Specifically, preferable alkali metal chalcogenides include, for example, Li ₂ O, LiO, Na ₂ S,
Na ₂ Se and NaO are mentioned, and preferred alkaline earth metal chalcogenides are, for example, CaO, B
aO, SrO, BeO, BaS, and CaSe. Preferred alkali metal halides include, for example, LiF, NaF, KF, LiCl, K
Cl and NaCl. Preferred alkaline earth metal halides include, for example, Ca
Examples include fluorides such as F ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ , and halides other than fluorides.

Semiconductors constituting the electron injection layer include Ba, Ca, Sr, Yb, Al, Ga, In, and L.
Examples thereof include oxides, nitrides, oxynitrides, and the like containing at least one element of i, Na, Cd, Mg, Si, Ta, Sb, and Zn alone or in combination of two or more. Further, the inorganic compound constituting the electron injection layer is preferably a microcrystalline or amorphous insulating thin film.
If the electron injection layer is composed of these insulating thin films,
Since a more uniform thin film is formed, pixel defects such as dark spots can be reduced. Examples of such inorganic compounds include the above-described alkali metal chalcogenides, alkaline earth metal chalcogenides, halides of alkali metals, and halides of alkaline earth metals.

(2) Electron Affinity The electron affinity of the electron injection layer in the first embodiment is preferably set to a value within the range of 1.8 to 3.6 eV. When the value of the electron affinity is less than 1.8 eV, the electron injecting property tends to decrease, which tends to increase the driving voltage and decrease the luminous efficiency. On the other hand, when the value of the electron affinity exceeds 3.6 eV, the light emission Complexes with low efficiency can be easily generated, and generation of blocking junction can be efficiently suppressed. Therefore, the electron affinity of the electron injection layer is set to 1.
The value is more preferably in the range of 9 to 3.0 eV, and even more preferably in the range of 2.0 to 2.5 eV.

Preferably, the difference in electron affinity between the electron injection layer and the organic light emitting layer is set to a value of 1.2 eV or less.
More preferably, the value is 0.5 eV or less. The smaller the difference in electron affinity, the easier the electron injection from the electron injection layer to the organic light emitting layer, and an organic EL device capable of high-speed response can be obtained.

(3) Energy Gap The energy gap (bandgap energy) of the electron injection layer in the first embodiment is preferably set to 2.7 eV or more, more preferably 3.0 eV or more. preferable. As described above, when the value of the energy gap is set to a predetermined value or more, for example, 2.7 eV or more, holes are less likely to move beyond the organic light emitting layer to the electron injection layer. Therefore, the efficiency of recombination of holes and electrons is improved, the emission luminance of the organic EL element is increased, and the emission of the electron injection layer itself can be avoided.

(4) Structure Next, the structure of the electron injection layer made of an inorganic compound will be described. The structure of the electron injection layer is not particularly limited, and may be, for example, a single-layer structure, a two-layer structure, or a three-layer structure. Also, the thickness of the electron injection layer is not particularly limited, but is preferably, for example, a value in the range of 0.1 nm to 1000 nm. The reason for this is that when the thickness of the electron injection layer made of an inorganic compound is less than 0.1 nm, the electron injection property may be reduced, or the mechanical strength may be reduced. This is because if the thickness of the electron injection layer exceeds 1000 nm, the resistance becomes high, and high-speed response of the organic EL element becomes difficult, or a long time is required for film formation. Therefore, the thickness of the electron injection layer made of an inorganic compound is more preferably set to a value in the range of 0.5 to 100 nm, and even more preferably to a value in the range of 1 to 50 nm.

(5) Forming Method Next, a method of forming an electron injection layer will be described. The method of forming the electron injection layer is not particularly limited as long as it can be formed as a thin film layer having a uniform thickness. For example, a vacuum deposition method, a spin coating method, a casting method, an LB method, a sputtering method, and the like. Method can be applied.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, for example, even when a plurality of inorganic compounds are used for the inorganic thin film layer, an inorganic thin film layer having a uniform composition ratio of constituent materials is obtained,
As a result, an object of the present invention is to provide a manufacturing method capable of obtaining a high emission luminance even at a low driving voltage and efficiently obtaining an organic EL element having excellent durability. That is, the first feature of the fourth embodiment is that the inorganic thin film layer is formed using a specific target and a high-frequency magnetron sputtering method. Further, in the fourth embodiment, for example, even when a plurality of organic light-emitting materials are used, an organic light-emitting layer having a uniform composition ratio of constituent materials can be obtained. An object of the present invention is to provide a manufacturing method capable of efficiently obtaining an organic EL device which can obtain luminance and has excellent durability.

As a fourth embodiment, a vacuum chamber for high-frequency magnetron sputtering and a vacuum chamber for vacuum evaporation were separately provided, and they were connected in advance to perform vacuum evaporation. Thereafter, it is preferable that the substrate be moved into a vacuum chamber for a high-frequency magnetron sputtering method by a transfer device. In describing the manufacturing method of the fourth embodiment, for convenience, an organic EL
The configuration of the element is the same as that of the third embodiment.

According to the manufacturing method of the fourth embodiment, the following layers were formed by the following manufacturing methods. Anode layer: Vacuum evaporation method Inorganic thin film layer: High-frequency magnetron sputtering method Hole transport layer: Vacuum evaporation method Organic light emitting layer: Vacuum evaporation method Electron injection layer: Vacuum evaporation method Cathode layer: Vacuum evaporation method

(1) Formation of Anode Layer and Inorganic Thin Film Layer In forming the anode layer and the inorganic thin film layer by a high-frequency magnetron sputtering method, it is preferable to use a target comprising an inorganic compound of Group A and Group B. Specifically, such a target contains at least a predetermined ratio of an inorganic compound of Group A and Group B, and is prepared by a solution method (coprecipitation method) (concentration: 0.01 to 10 mol / l,
Solvent: Polyhydric alcohol, etc., Precipitating agent: Potassium hydroxide, etc., and uniform mixing of raw materials (average particle diameter 1 μm or less) by physical mixing method (agitator: ball mill, bead mill, etc., mixing time: 1 to 200 hours). After mixing, sintering (temperature 12
00 to 1500 ° C., time 10 to 72 hours, more preferably 24 to 48 hours), and further molding (press molding or H
What was obtained by IP molding etc.) is preferable. The targets obtained by these methods are characterized by having uniform characteristics. In addition, the rate of temperature rise during molding is 1
It is more preferable to set the value in the range of ５０50 ° C./min. However, since the composition ratio and the like can be adjusted only by sputtering conditions, the inorganic compounds of Group A and Group B are
Separately, sputtering is also preferred.

The conditions of the high-frequency magnetron sputtering are not particularly limited, but in an inert gas such as argon, the degree of vacuum is 1 × 10 ⁻⁷ to 1 × 10 ⁻³ Pa, and the film formation rate is 0.01 to 10 μm. 50 nm / sec, substrate temperature -50 to 30
It is preferable to adopt the condition of 0 ° C. Under such sputtering conditions, a dense inorganic thin film layer having a uniform film thickness can be formed.

(2) Formation of Organic Light-Emitting Layer A method of forming an organic light-emitting layer by simultaneously evaporating different evaporation materials will be described with reference to FIGS. That is, using the vacuum deposition apparatus 201 as an example, the substrate 203
A rotation axis 213 for rotating the substrate 203
A is set, and the evaporation sources 212A to 212F are arranged at positions away from the rotation axis 213A of the substrate 203, respectively, and the plurality of evaporation sources 212A to 212F arranged to face the substrate 203 while rotating the substrate 203. In this case, different evaporation materials are simultaneously evaporated to perform evaporation.

Here, the vacuum evaporation apparatus 201 shown in FIGS. 4 and 5 includes a vacuum chamber 210, a substrate holder 211 for fixing the substrate 203, which is installed in the upper portion of the vacuum chamber 210, It comprises a plurality (six) of evaporation sources 212A to 212F, which are arranged below the holder 211 and are opposed to each other, for filling an evaporation material. The inside of the vacuum chamber 210 can be maintained at a predetermined reduced pressure state by an exhaust means (not shown). In addition,
Although the number of vapor deposition sources is shown in the drawing as six, the number is not limited thereto, and may be five or less, or seven or more.

The substrate holder 211 has a holding portion 212 for supporting the peripheral portion of the substrate 203, and is configured to horizontally hold the substrate 203 in the vacuum chamber 210. At the center of the upper surface of the substrate holder 211, a rotating shaft 213 for rotating (rotating) the substrate 203 is provided upright in the vertical direction. The rotating shaft 213 is connected to a motor 214 serving as a rotation disturbance unit.
4 rotates the substrate 203 held by the substrate holder 211 together with the substrate holder 211 into the rotating shaft 2.
13 rotates around the center of rotation. That is, at the center of the substrate 203, the rotation axis 213A of the rotation shaft 213 is set in the vertical direction.

Next, a method for forming an organic light emitting layer 12 on a substrate 203 from two kinds of organic light emitting materials (host material and dopant material) using the vacuum evaporation apparatus 201 configured as described above will be described. This will be specifically described. First, a substrate 203 having a flat square shape as shown in FIG. 4 is prepared, and this substrate 203 is locked to the holding portion 212 of the substrate holder 211 to be in a horizontal state. In this regard, the substrate 203 shown in FIG.
Is held in a horizontal state, which indicates this.

Here, when forming the organic light-emitting layer 12, two adjacent evaporation sources 212B on the virtual circle 221 are formed.
And 212C are filled with a host material and a dopant material, respectively, and then the pressure in the vacuum chamber 210 is reduced to a predetermined degree of vacuum, for example, 1.0 × 10 ⁻⁴ Torr by an exhaust means. Next, the evaporation sources 212B and 212C are heated to simultaneously evaporate the host material and the dopant material from the evaporation sources 212B and 212C, respectively, and the motor 214 is rotated and disturbed to move the substrate 203 along the rotation axis 213A by a predetermined amount. Speed, for example 1-100
Rotate at rpm. Thus, the organic light emitting layer 12 is formed by co-evaporating the host material and the dopant material while rotating the substrate 203. At this time, as shown in FIG. 5, the evaporation sources 212B and 212C are provided at positions that are shifted from the rotation axis 213A of the substrate 203 by a predetermined distance M in the horizontal direction. The angle of incidence on the substrate 203 of a deposition material such as a dopant or a dopant material can be changed regularly. Therefore, the deposition material can be uniformly attached to the substrate 203, and within the film surface of the electron injection layer 14,
The composition ratio of the deposition material is uniform, for example, the concentration unevenness is ± 10%
It is possible to reliably form a thin film layer (in terms of mol). Further, by performing the vapor deposition in this manner, the substrate 203 does not need to revolve, so that no space or equipment is required, and a film can be formed economically with a minimum space. Revolving the substrate means rotating around a rotation axis other than the substrate, and requires a larger space than when rotating.

In performing the simultaneous vapor deposition, the shape of the substrate 203 is not particularly limited. For example, as shown in FIG. 4, when the substrate 203 is a short flat plate, the rotation axis 213A of the substrate 203 is Virtual circle 221 at the center
When a plurality of evaporation sources 212A to 212F are arranged along the circumference of the circle, and the radius of the virtual circle 221 is M and the length of one side of the substrate 203 is L, M> (1/2) × L It is desirable to satisfy When the lengths of the sides of the substrate 203 are not the same but different, the length of the longest side is set to L. With this configuration, a plurality of deposition sources 2
From 12A to 212F, the incident angle of the deposition material with respect to the substrate 203 can be made the same, so that the composition ratio of the deposition material can be more easily controlled. In addition, with this configuration, the evaporating material is evaporated at a constant incident angle with respect to the substrate 203, so that the evaporating material does not enter vertically and the uniformity of the composition ratio in the film plane is further improved. be able to.

In carrying out the manufacturing method according to the fourth embodiment, as shown in FIG.
To 212F are arranged on the circumference of a virtual circle 221 centered on the rotation axis 213A of the substrate 203, and the plurality of evaporation sources 21
When the number (number) of the arrangements 2A to 212F is n, it is preferable that the evaporation sources 212A to 212F are arranged at an angle of 360 ° / n from the center of the virtual circle 221. For example, when six evaporation sources 212 are provided, the virtual circle 22
It is preferable to arrange them at an angle of 60 ° from the center of one. With this arrangement, a plurality of deposition materials can be sequentially formed on each portion of the substrate 203 so that a thin film layer having a different composition ratio can be easily formed in the thickness direction of the film. can do.

Next, the composition uniformity of the organic light emitting layer formed by the above-mentioned simultaneous vapor deposition method will be described in more detail. As an example, using Alq as a host material and Cs as a dopant material, a thin film layer having a thickness of about 1000 angstroms (set value) was simultaneously deposited under the following conditions while rotating the substrate 203 shown in FIG. 6 at 5 rpm. . Alq steaming speed: 0.1-0.3 nm / s Cs steaming speed: 0.1-0.3 nm / s Alq / Cs film thickness: 1000 Å (set value)

Next, the film thickness of the obtained thin film layer at the measurement points (4A to 4M) on the glass substrate 203 shown in FIG.
The 1 (Al in Alq) composition ratio (atomic ratio) was measured using an X-ray photoelectron spectrometer (XPS). The measurement points (4A to 4M) on the glass substrate 203 shown in FIG.
03 is divided into 16 equal parts in advance, and the length P of one side is 50
mm square sections are set, and arbitrary corners (13 places) in these sections are set. Table 1 shows the obtained results.

[0073]

[Table 1]

On the other hand, under the same vapor deposition conditions as in the above simultaneous vapor deposition method except that the
A thin film layer of 0 Å (set value) was formed. The film thickness and the composition ratio (atomic ratio) of Cs / Al at the measurement points (4A to 4M) of the obtained thin film layer were measured, and the results are shown in Table 2.

[0075]

[Table 2]

As is clear from these results, according to the above-described simultaneous vapor deposition method, the measurement point (4A
４4M), the film thickness is extremely uniform within a range of 1008 to 1093 angstroms, and Cs /
It was confirmed that a thin film layer having a very uniform composition ratio of Al (atomic ratio) in the range of 1.0 to 1.10. On the other hand, when a manufacturing method different from the above-described simultaneous vapor deposition method is used, the measurement points (4A to 4A
M), the film thickness is a value within the range of 884 to 1067 angstroms, and the composition ratio of Cs / Al is 0.6 to 1.
It was confirmed that the value was within the range of 3.

[0077]

EXAMPLES Example 1 (1) Preparation for Manufacturing Organic EL Element In manufacturing the organic EL element of Example 1, first, a 1.1 mm thick, 25 mm long, and 75 mm wide transparent glass substrate was used. And a thickness of 75 made of ITO as an anode layer.
nm of a transparent electrode film was formed. Hereinafter, the glass substrate and the anode layer are collectively referred to as a substrate. Subsequently, the substrate was ultrasonically cleaned with isopropyl alcohol, dried in an N ₂ (nitrogen gas) atmosphere, and then cleaned for 10 minutes using UV (ultraviolet light) and ozone.

(2) Formation of Inorganic Thin Film Layer Next, the substrate on which the anode layer was formed was placed in a vacuum chamber shared by a high-frequency sputtering device and a vacuum evaporation device, and tin oxide and ruthenium oxide constituting the inorganic thin film layer were formed. (Composition ratio: 10: 1) was mounted in a vacuum chamber. Next, the degree of vacuum in the vacuum chamber was 1 × 10
^Under reduced pressure to ⁻⁵ Torr, sputtering was performed under the conditions of an output of 100 W and a substrate temperature of 200 ° C. to form an inorganic thin film layer having a thickness of 10 nm.

(3) Formation of Organic Light-Emitting Layer, etc. Then, the apparatus is switched to a vacuum vapor deposition apparatus, and as shown in FIG. The aromatic compound (DPVTP) to be deposited is used as the vapor deposition source 212B, the aromatic compound (DPAVBi) which is also a part of the organic light emitting layer is used as the vapor deposition source 212C, and the organic compound (Al
q) was charged into the evaporation source 212D, metal (Al) constituting a part of the cathode layer was charged into the evaporation source 212E, and metal (Li) forming a part of the cathode layer was charged into the evaporation source 212F. Next, the pressure in the vacuum chamber was reduced to a degree of vacuum of 1 × 10 ⁶ Torr or less, and then an organic light emitting layer, an electron injection layer, and a cathode layer were sequentially laminated on the anode layer and the inorganic thin film layer of the substrate to form an organic layer. An EL device was obtained. At this time, from the formation of the organic light emitting layer to the formation of the cathode layer, the same vacuum condition was maintained without breaking the vacuum state.

More specifically, DPVTP and DPAVBi were simultaneously evaporated from the evaporation source 212B and the evaporation source 212C under the following conditions, respectively, to form an organic light emitting layer on the inorganic thin film layer. DPVTP deposition rate: 0.5 nm / s DPAVBi deposition rate: 0.1 nm / s DPVTP / DPAVBi film thickness: 40 nm That is, the simultaneous deposition was performed according to the method described in the fourth embodiment. That is, the used evaporation source 212
B and 212C are respectively provided at positions shifted by 30 mm in the horizontal direction from the rotation axis of the substrate. In this state, heating is performed to simultaneously evaporate DPVTP and DPAVBi from each evaporation source, and rotate the motor. Then, the organic light emitting layer was formed while rotating the substrate at 5 rpm along the rotation axis. Next, the evaporation source 21
From 2D, under the following conditions, Alq was evaporated to form an electron injection layer on the organic light emitting layer. Alq evaporation rate: 0.2 nm / s Alq film thickness: 5 nm Finally, Al was evaporated from the evaporation source 212E and Li was evaporated from the evaporation source 212F to form a cathode layer on the electron injection layer, and the organic EL element was obtained. And Al steaming speed: 1 nm / s Li steaming speed: 0.01 nm / s Al / Li film thickness: 200 nm

(4) Evaluation of Organic EL Device The cathode layer in the obtained organic EL device was minus (-).
Electrode and anode layer as plus (+) electrode, 8
V DC voltage was applied. The current density at this time is 1.5
m / cm ² and the emission luminance is 127 nit (cd /
m ² ). It was also confirmed that the emission color was blue. Further, as a durability evaluation, when driving at a constant current of 10 mA / cm ² , even after a lapse of 1000 hours or more,
In particular, no generation of leakage current was observed.

[0082]

[Table 3]

[0083]

[Table 4]

[Examples 2 to 4] An organic EL device was prepared in the same manner as in Example 1 except that the kind and the addition ratio of the inorganic compound of Example 1 were changed, and emission luminance and the like were evaluated. Table 3 shows the obtained results.

Comparative Example 1 The structure of the organic EL device of Comparative Example 1 was the same as the structure of the organic EL device of Example 1 except that no inorganic thin film layer was formed in Example 1. The same as in Example 1. Then, a DC voltage of 10 V was applied to the obtained organic EL device in the same manner as in Example 1.
As a result, blue light emission was observed. At that time, the current density was 2.2 mA / cm ² , and the light emission luminance was 127 ni.
t (cd / m ² ). Further, when the device was driven at a constant current of 10 mA / cm ² in the same manner as in Example 1, 100
Before 0 hour, a leak current occurred, and light emission of the organic EL element stopped.

[Comparative Example 2] The structure of the organic EL element of Comparative Example 1 is the same as the structure of the organic EL element of Example 1.
Unlike Example 1, only tin oxide is used for the inorganic thin film layer. Then, a DC voltage of 10 V was applied to the obtained organic EL device in the same manner as in Example 1. As a result, blue light emission was observed, and the current density at that time was 0.9 mA / c.
m ² , and the light emission luminance was 68 nit (cd / m ² ). However, as in Example 1, 10 mA / cm ²
When driving at a constant current at, even after 1000 hours,
No leak current occurred.

Comparative Example 3 The structure of the organic EL element of Comparative Example 1 is the same as the structure of the organic EL element of Example 1.
Unlike the first embodiment, only the aluminum nitride is used for the inorganic thin film layer. Then, a DC voltage of 10 V was applied to the obtained organic EL device in the same manner as in Example 1. as a result,
Blue light emission was observed, and the current density at that time was 0.6.
mA / cm ² , and the emission luminance was 20 nit (cd /
m ² ). However, as in Example 1, 10
When the device was driven at a constant current of mA / cm ² , no leak current occurred even after 1000 hours.

[0088]

As described above in detail, according to the present invention, even when an organic EL element is provided with an inorganic thin film layer, for example, the inorganic thin film layer is formed by combining a plurality of specific inorganic compounds. With this configuration, an electric charge can be injected by forming an intermediate level in the inorganic thin film layer without using the tunnel effect. That is, according to the present invention, while having excellent durability, the driving voltage is low,
In addition, it has become possible to provide an organic EL element having a high emission luminance and a method for manufacturing an organic EL element capable of efficiently obtaining such an organic EL element.

[Brief description of the drawings]

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

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

FIG. 3 is a cross-sectional view of an organic EL device according to a third embodiment.

FIG. 4 is a perspective view of a vacuum evaporation apparatus according to a fourth embodiment.

FIG. 5 is a sectional view of a vacuum evaporation apparatus according to a fourth embodiment.

FIG. 6 is a diagram provided for describing measurement points on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Anode layer 12 Inorganic thin film layer 13 Hole transport layer 14 Organic light emitting layer 15 Electron injection layer 16 Cathode layer 20 Translucent substrate (glass substrate) 30 Substrate 100, 102, 104 Organic EL element 201 Vacuum evaporation apparatus 203 Substrate 210 Vacuum Vessel 211 Substrate holder 212 Holder 212A to 212F Evaporation source 213 Rotating shaft 213A Rotating axis 214 Motor 221 Virtual circle

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/10 H05B 33/10 33/14 33/14 B F-term (Reference) 3K007 AB00 AB02 AB04 AB06 AB13 AB18 BB01 BB05 CA01 CB01 DA00 DB03 EA04 EB00 EC00 FA01 FA03

Claims (9)

[Claims] 1. An organic electroluminescent device having at least an anode layer, an organic light emitting layer, and a cathode layer in this order, wherein between the anode layer and the organic light emitting layer and between the cathode layer and the organic light emitting layer, Alternatively, an inorganic thin film layer is provided between any one of them, and when an inorganic thin film layer is provided between the anode layer and the organic light emitting layer, an intermediate level of the inorganic thin film layer is ionized by the organic light emitting layer. When the value is smaller than the potential and an inorganic thin film layer is provided between the cathode layer and the organic light emitting layer,
An organic electroluminescence device, wherein the intermediate level of the inorganic thin film layer is set to a value larger than the electron affinity of the organic light emitting layer, and charge injection is performed via the intermediate level of the inorganic thin layer. 2. An organic electroluminescence device having at least an anode layer, an organic light emitting layer, and a cathode layer in this order, wherein: between the anode layer and the organic light emitting layer and between the cathode layer and the organic light emitting layer; Alternatively, an organic electroluminescent device comprising an inorganic thin film layer containing at least one compound selected from Group A and at least one compound selected from Group B between any one of the two. Group A: Si, Ge, Sn, Pb, Ga, In, Zn, C
d, Mg chalcogenides or nitrides thereof Group B: Periodic Table 5A to 8 Group Compounds 3. The relationship of Ba> Bh is satisfied, where Ba is a band gap energy value of the inorganic thin film layer and Bh is a band gap energy value of the organic light emitting layer. Organic electroluminescence element. 4. The method according to claim 1, wherein the inorganic compound of Group A is Si, Ge,
4. The organic electroluminescent device according to claim 2, wherein the organic electroluminescent device is a chalcogenide of Sn, Zn, Cd and Mg or a nitride thereof. 5. The method according to claim 1, wherein the inorganic compound of Group B is Ru, V, M
5. An oxide of o, Re, Pd and Ir.
The organic electroluminescent element according to any one of the above. 6. The total amount of the inorganic thin film layer is 100 a
t. %, The content of the inorganic compound of Group B is 0.1 to 50 at. 3. A value within a range of%.
The organic electroluminescence device according to any one of claims 1 to 5. 7. The inorganic thin film layer has a thickness of 1 to 100 nm.
The organic electroluminescent device according to any one of claims 1 to 6, which has a value in the range of: 8. The organic light-emitting layer according to the following general formula (1)
The organic electroluminescence device according to any one of claims 1 to 7, comprising at least one of the aromatic compounds having a styryl group represented by (3). Embedded image [In the general formula (1), Ar ¹ is an aromatic group having 6 to 40 carbon atoms, and Ar ² , Ar ³ , and Ar ⁴ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. And A
At least one of r ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is an integer of 1 to 6. ] [In the general formula (2), Ar ⁵ is an aromatic group having 6 to 40 carbon atoms, Ar ⁶ and Ar ⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and Ar 5 ⁵ , Ar ⁶
And at least one of Ar ⁷ is substituted with a styryl group, and the condensation number m is an integer of 1 to 6. ] [In the general formula (3), Ar ⁸ and Ar ^{14 each} have 6 carbon atoms.
Ar ^{9 to} Ar ¹³ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms,
At least one is substituted with a styryl group, condensation number p, q, r, s of r ⁸ to Ar ¹⁴ are each 0 or 1
It is. ] 9. The method for producing an organic electroluminescence device according to claim 1, wherein
A method for manufacturing an organic electroluminescent device, wherein the inorganic thin film layer is formed by a sputtering method, and the organic light emitting layer is formed by a vacuum deposition method.