JP2002075661A - Organic el element and organic el display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element and its manufacturing method in which its manufacturing is easy, degradation of luminescence characteristics by oxygen or moisture is avoided, and generating of a dark spot is inhibited. SOLUTION: In the organic EL element formed by sandwiching an organic EL layer 13 between an anode 12 and a cathode 14, the cathode 14 has a laminating structure constituted of a 1st electric conduction film 14a contacting the organic EL layer 13, which includes an alkali metal or an alkaline earth metal, and a 2nd electric conduction film 14b containing at least one sort of metals chosen from a group which consists of Ru(ruthenium), Rh(rhodium), Ir(iridium), Os(osmium), and Re(rhenium), or the oxide of those.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL device having a structure in which an organic EL (electroluminescence) layer is sandwiched between a pair of electrodes, a method of manufacturing the same, and an organic EL display device in which a plurality of organic EL devices are arranged. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, an organic EL element (organic LED) has attracted attention as a self-luminous element. The organic EL element has an advantage that it can be driven at a lower voltage than an inorganic EL element, and has an advantage that it can be manufactured without using a complicated manufacturing process as compared with a conventional inorganic LED.

The organic EL device has a higher response speed, a simpler device structure, and does not require a backlight, as compared with a liquid crystal display device widely used as a display of a portable device at present. There is an advantage that the weight can be reduced. Further, since the organic EL element is a solid-state element, it has an advantage that it is resistant to impact. Organic EL elements
It has a structure in which an EL light emitting layer (organic EL layer) is sandwiched between a cathode and an anode. A metal having a high work function is used for the anode, and a metal having a low work function is used for the cathode, so that the supply of holes and electrons is smooth. Generally, ITO (indium-tin oxide) which is a transparent conductor is used for the anode. In addition, Na (sodium), Na-K (sodium-potassium) alloy, Mg
A metal containing an alkali metal or an alkaline earth metal such as (magnesium), Li (lithium), a Mg / Cu (magnesium / copper) mixture, and In (indium) is used.

The EL light emitting layer is made of, for example, Alq ₃ , BeB
q ₃ , DCM, DPVBi, quinacridone derivatives, coumarin and the like are used. In general, the low-molecular EL luminescent layer is manufactured by a vapor deposition method, and the high-molecular EL luminescent layer is manufactured by a spin coating method. Therefore, there is an advantage that the polymer EL light emitting layer is easier to form a film and has higher mechanical strength.

Attempts have been made to form a buffer layer on the cathode side or anode side in order to lower the operating threshold voltage of the organic EL element. For example, as a conventional buffer layer, between the anode and the organic EL layer, ruthenium oxide (hereinafter referred to as RuO), molybdenum oxide (hereinafter referred to as Mo)
O) or a layer made of vanadium oxide (hereinafter referred to as VO) may be formed. These R
The layer made of uO, MoO or VO is formed by a sputtering method.

By the way, in the organic EL device, when used for a long time, the luminous efficiency is reduced due to the influence of oxygen and moisture.
A defect called a dark spot occurs. This is because the alkali metal or alkaline earth metal used for the cathode is easily oxidized. JP-A-7-1695
No. 67 discloses that a laminate of an anode, an organic EL layer, and a cathode is formed of a layer made of a material that adsorbs, occludes, or consumes oxygen (hereinafter, referred to as a layer) in order to avoid deterioration of the luminous efficiency of the organic EL element due to oxygen or moisture. (Referred to as a sealing layer). As a material for the sealing layer, a material in which platinum, palladium, rhodium, ruthenium, or silver is supported on a substance such as magnesium oxide, magnesium carbonate, iron oxide, titanium oxide, bentonite, or the like at a concentration of 5% by weight or less, or the like is used. Has been described.

[0007]

SUMMARY OF THE INVENTION The present inventor considers that the conventional organic EL device has the following problems. That is, the organic E disclosed in JP-A-7-169567
In the L element, a laminate of an anode, an organic EL layer, and a cathode is covered with an insulating sealing layer. Therefore, it is necessary to join extraction electrodes to the anode and the cathode, respectively, and to extract the outside of the sealing layer. This complicates the manufacturing process and causes an increase in product cost.

As described above, a buffer layer made of RuO, MoO or VO may be formed by a sputtering method in order to lower the operation threshold voltage. But,
This method has a disadvantage that large irregularities are formed. For example, the RuO ₂ layer is formed by sputtering
If it is going to be formed to a thickness of 500 to 1000
Hillocks of Å occur locally. For this reason, if the thickness of the organic EL layer is reduced, short-circuit failure may occur.

Further, when producing a full-color image display device using an organic EL element, a red-emitting organic EL element
It is necessary to arrange a green light emitting organic EL element and a blue light emitting organic EL element in a certain order in the horizontal and vertical directions. Therefore, a technique for finely processing the organic EL layer is required. As a fine processing technique used for manufacturing a semiconductor device, a lift-off method and an etching method are known. However, in the case of a single-color image display device, for example, it is conceivable that the upper electrode (cathode) of each pixel is formed by a lift-off method, but it is difficult to apply the lift-off method to manufacture of a full-color display device. Further, since the organic EL layer is a low molecular weight or high molecular weight organic substance, it cannot be processed by a fine processing technique such as dry etching.

The present invention has been made in view of the above-mentioned problems, and is an organic EL device that is easy to manufacture, avoids deterioration of light emission characteristics due to oxygen or moisture, and suppresses the generation of dark spots. And a method for producing the same. In addition, the present invention provides an organic EL device that has a small unevenness on the surface of the buffer layer and can prevent the occurrence of short circuit failure.
It is an object to provide an L element and a method for manufacturing the same.

Another object of the present invention is to provide a multicolor light emitting organic EL display device capable of displaying an image and a method of manufacturing the same.

[0012]

According to a first aspect of the present invention, there is provided an organic EL device having an organic EL element formed by sandwiching an organic EL layer between an anode and a cathode. A first conductive film containing an earth metal and in contact with the organic EL layer, and selected from the group consisting of Ru (ruthenium), Rh (rhodium), Ir (iridium), Os (osmium), and Re (rhenium); It has a laminated structure with a second conductive film containing at least one kind of metal or an oxide thereof.

The second conductive film containing a quasi-noble metal such as Ru, Rh, Ir, Os and Re is converted to the first conductive film by oxidizing a quasi-noble metal such as Ru, Rh, Ir, Os and Re. To prevent oxygen and moisture from entering. Also, Ru, R
Since the oxides of semi-noble metals such as h, Ir, Os, and Re have conductivity, even if they are oxidized, their functions as electrodes are not impaired. Thereby, in the organic EL device of the present invention, the oxidation of the first conductive film containing an alkali metal or an alkaline earth metal is prevented, and the generation of dark spots for a long period is avoided.

As the second conductive film, a TiN film or a TiN film
Even when a stacked film of N and Ti is used, the invasion of oxygen and moisture into the first conductive film can be similarly prevented, and a highly reliable organic EL element can be obtained. Claim 3 of the present application
In the method for manufacturing an organic EL device described in 1 above, after forming an anode and an organic EL layer on a substrate, a first conductive film containing an alkali metal or an alkaline earth metal is formed by a sputtering method, and Ru is formed thereon. , Rh, Ir, Os and Re, at least one metal selected from the group consisting of a metal and an oxide thereof is formed to form a second conductive film.

In the present invention, the oxidation of alkali metal or alkaline earth metal in the first conductive film by the second conductive film can be performed without covering the laminate of the anode, the organic EL layer, and the cathode with an insulating film. Can be prevented. Therefore, an organic EL device having high reliability over a long period of time can be easily manufactured. In the organic EL device according to the present invention, at least one metal selected from the group consisting of Ru (ruthenium), Mo (molybdenum) and V (vanadium) is provided between the anode and the organic EL layer. In addition, only the surface on the organic EL layer side has an oxidized buffer layer.

For example, a conductive film (buffer layer) containing at least one metal of Ru, Mo and V is formed by a sputtering method, and short-time annealing, laser annealing,
Only the surface of the conductive film is oxidized by a method such as plasma oxidation or anodic oxidation. Thereby, a thin oxide film can be formed, and unevenness on the surface of the buffer layer can be reduced. Therefore, even if the thickness of the organic EL layer is reduced, occurrence of a short circuit can be avoided.

In the organic EL display device according to the present invention, two or more regions having different emission colors are formed by changing the conjugate length of the polymer constituting the organic EL layer. For example, poly [3- (4-alkylphenyl) thiophene]
Is an organic EL material that emits red light, but its conjugate length changes when it is irradiated with ultraviolet light, and emits green light or blue light depending on the amount of ultraviolet light irradiated. Such organic E
By using the L material, an organic EL display device that emits multicolor light can be easily manufactured.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a sectional view showing an organic EL device according to a first embodiment of the present invention. On the glass substrate 11, an ITO film is formed as the anode 12 to a thickness of about 2000 °. In a predetermined region above the anode 12, a poly [3- (4-)
Alkylphenyl) thiophene] film having a thickness of about 1500 °.

Further, a cathode 14 is provided on the organic EL layer 13.
Conductive film 14a made of a conductor containing Mg
And a second conductive film 14b made of a conductor containing Ru is formed as a laminated film having a two-layer structure. In this example, the first
The thickness of the conductive film 14a is about 1000 °, and the thickness of the second conductive film 14b is about 500 °. Anode 12 is IT
The conductor is not limited to O, and a conductor having a large work function can be used. However, if light is emitted toward the substrate 11, the anode 12 needs to be a conductor that transmits light.

The first conductive film 14a may be formed of a conductor having a small work function and containing an alkali metal or an alkaline earth metal. For example, as the material of the first conductive film 14a, MgAg, AlLi, LiF, or the like can be used. Here, the second conductive film 14a is made of MgAg. Further, the second conductive film 14b is not limited to the above-described conductor containing Ru, but is a conductor having a high barrier property against oxygen, specifically, Ru, Rh, or the like.
It may be made of a metal selected from the group consisting of Ir, Os and Re or an oxide thereof. Ru, Rh, Ir,
Os and Re also have oxides. Therefore, the conductivity of the cathode 14 is not impaired by the oxidation.

As the second conductive film 14b, TiN
A film or a stacked film of TiN and Ti (referred to as a TiN / Ti film) may be used. These films also have good barrier properties against oxygen, and can prevent oxidation of the first conductive film 14a. In addition, even if the TiN film and the TiN / Ti film are exposed to an atmosphere containing oxygen for a long time, the conductivity is not impaired.

Further, as the second conductive film 14b, Ru,
A conductive film containing a metal selected from the group consisting of Rh, Ir, Os, and Re or an oxide thereof, and a TiN film or TiN
/ Ti film may be used. In the thus configured organic EL device of the present embodiment, the anode 12
When a positive voltage is applied to the cathode 14 and a negative voltage is applied to the cathode 14, the organic EL layer 1
3 emits light.

In this embodiment, since the second conductive film 14b containing Ru is formed on the first conductive film 14a containing Mg which is an alkali metal, the organic EL element can remove oxygen or moisture. Ru in the second conductive film 14b is oxidized to prevent oxygen from entering the first conductive film 14a even when exposed to an atmosphere containing the same for a long time. Therefore, oxidation of Mg in the first conductive film 14a is avoided.

As a result, in the organic EL device of the present embodiment, deterioration of the light emission characteristics due to oxygen or moisture is avoided, and generation of dark spots is suppressed. Further, since oxidation of the first conductive film 14a is avoided, the organic EL layer 13 and the first
Of the conductive film 14a is also prevented. Furthermore, it is not necessary to cover the laminated body of the anode 12, the organic EL layer 13, and the cathode 14 with an insulator, and the production is easy.

Hereinafter, a method for manufacturing the organic EL device of the present embodiment will be described. First, an ITO film is formed to a thickness of about 2000 ° on the entire upper surface of the glass substrate 11 by a sputtering method. Next, poly [3- (4-alkylphenyl) thiophene] is deposited to a thickness of 1500 ° on the entire upper surface of the glass substrate 11 by spin coating to form an organic EL layer 13. In the present embodiment, the material of the organic EL layer 13 is not limited to the above poly [3- (4-alkylphenyl) thiophene].
Various low-molecular or high-molecular organic EL light-emitting materials can be used.

Next, the organic EL layer 13 is formed by sputtering.
A first conductive film 14a is formed by forming a film of MgAg to a thickness of about 1000 °, and a second conductive film 14b is formed by forming a film of Ru to a thickness of 500 °. Next, a metal such as Au or Al is sputtered using a metal mask to form a pair of terminals connected to the anode 12 and the cathode 14, respectively. Thereby, the organic EL device of the present embodiment is completed.

As shown in FIG. 2, the anode 12 is formed in a stripe shape, and the cathode 14 is formed in a stripe shape in a direction intersecting at right angles to the anode 12, so that a plurality of organic materials are formed on the glass substrate 11. EL element (anode 12 and cathode 1
A display device in which (intersections of 4) 15 are arranged in a matrix can be provided. In this display device, similarly to the simple matrix type liquid crystal display device, a positive signal is sequentially supplied to a plurality of anodes 12 arranged in the vertical direction at a timing synchronized with the horizontal synchronization signal, and the horizontal direction is set within one horizontal synchronization period. By sequentially supplying a negative signal to the plurality of cathodes 14 arranged in a row, a desired image can be displayed.

The present invention can be applied to an active matrix type organic EL display device. That is,
As shown in FIG. 3, a cathode 14 is formed for each pixel, and a voltage applied to the cathode 14 via a switch element 19 connected to a data line 16, a power supply line 17 and a scanning line 18 is applied to each pixel. , A desired image can be displayed. In this case, since the anode 12 serves as an electrode common to each pixel, there is no need to perform patterning.

Further, in the above embodiment, the anode 1
The organic EL layer 13 is formed directly on the
Although the case where the cathode 14 is formed directly on the substrate has been described, a buffer layer may be provided between the anode 12 and the organic EL layer 13 or between the organic EL layer 13 and the cathode 14. (Second Embodiment) FIG. 4 is a sectional view showing a method of manufacturing an organic EL device according to a second embodiment of the present invention. This embodiment is an example of a method for manufacturing an organic EL device having a buffer layer between an anode and an organic EL layer.

First, as shown in FIG. 4A, the ITO is deposited on the upper side of the glass
To form an anode (lower electrode) 22. next,
Ru (ruthenium) is deposited on the anode 22 by sputtering.
Is formed to a thickness of 300 ° to form a buffer layer 23. RTA (Rapid Thermal) heated by a lamp
Annealing) Short-time annealing (RTA) is performed at 700 ° C. for 3 to 5 seconds using an apparatus. By this short annealing, Ru on the surface of the buffer layer 23 is oxidized. In this case, since RuO is generated in a very short time, the particle size of RuO is small, and the formation of large irregularities on the surface of the buffer layer 23 is avoided.

The thickness of the buffer layer 23 (thickness before RTA) is preferably set to 500 ° or less. This is because when the thickness of the buffer layer 23 exceeds 500 °, the EL
Light generated in the light emitting layer 23 is absorbed by the buffer layer 23,
This is because the apparent light emission intensity decreases. Further, as the material of the buffer layer 23, Mo or V can be used in addition to the above-mentioned Ru.

Next, poly [3- (4-alkylphenyl) is formed on the buffer layer 23 by spin coating.
Thiophene] is deposited to a thickness of about 1500 ° to form an EL light emitting layer 24. The material of the EL light emitting layer 24 is the above poly [3
-(4-alkylphenyl) thiophene], and various organic ELs of low molecular weight or high molecular weight
Light emitting materials can be used.

Then, the organic EL layer 2 is formed by sputtering.
A film of AlLi is formed to a thickness of about 200 ° on the electrode 4 to form a cathode (upper electrode) 25. Thereby, the organic EL device of the present embodiment is completed. The material of the cathode 25 is not limited to the above-mentioned AlLi, and a conductor containing an alkali metal or an alkaline earth metal may be used. Further, as shown in the first embodiment, the cathode 25 may have a two-layer structure.

Hereinafter, the results of actually manufacturing the above-described organic EL device and actually measuring the operating threshold voltage and the surface unevenness of the buffer layer will be described. Using TDP / Alq ₃ as the material of the organic EL layer 24, an organic EL element was formed by the above method, and the operating threshold voltage was measured.
As a result, the light emission start voltage was 7 V when the buffer layer 23 was not provided, whereas the light emission start voltage was 7 V by the above method.
Was formed, the voltage became 3.5 V, and a decrease in the threshold voltage was confirmed.

The surface roughness of the buffer layer 23 was measured and found to be 50 ° to 100 ° in the present embodiment. On the other hand, when RuO ₂ is sputtered as the buffer layer, the unevenness of the surface of the buffer layer is 500 ° to 10 °.
It was 00 $. As a result, the effectiveness of the present embodiment was confirmed. According to the present embodiment, a Ru, Mo, or V metal film is formed as the buffer layer 23, and the surface of the buffer layer 23 is oxidized by RTA to effectively reduce RuO, MoO to lower the operation threshold voltage. Alternatively, VO is formed.
In this case, since the surface of the buffer layer 23 is oxidized in a short time, formation of large irregularities on the surface of the buffer layer 23 is avoided. Thereby, even if the thickness of the organic EL layer 24 is reduced, a short circuit between the anode 22 and the cathode 25 is avoided,
An organic EL element having a low operation threshold voltage is manufactured.

Note that this embodiment can be applied to a simple matrix type organic EL display device and an active matrix type organic EL display device as in the first embodiment. In the above embodiment, the surface of the buffer layer 23 is oxidized by using the RTA apparatus heated by a lamp. However, the surface of the buffer layer 23 is oxidized by laser irradiation, plasma oxidation, or anodic oxidation. Is also good.

When the surface of the buffer layer 23 is oxidized by laser irradiation, for example, a XeCl excimer laser is used, the laser beam is shaped into a narrow rectangular shape, and the laser beam is scanned in the width direction to shorten the surface of the buffer layer 23. Oxidize in time. The energy of the laser beam is, for example, 390 m
J / cm ² . When the surface of the buffer layer 23 is oxidized by the plasma oxidation method, a plasma containing oxygen is generated, and the surface of the buffer layer 23 is oxidized by exposing the surface of the buffer layer 23 to the plasma.
For example, the RFO ₂ plasma process, the processing time is 10
The plasma oxidation treatment is performed for 40 minutes at a pressure of 40 Pa and a power of 200 W.

Further, when the surface of the buffer layer 23 is oxidized by anodic oxidation, for example, a mixed solution of tartaric acid, ethylene glycol and ammonia solution is used as an electrolytic solution, and a Pt (platinum) electrode is used as an anode. And
The surface of the buffer layer 23 is anodized by passing a constant current of 5 mA to deposit a RuO ₂ film. When the surface of the buffer layer 23 is oxidized by these methods, the same effect as in the above embodiment can be obtained.

Third Embodiment FIGS. 5 and 6 are plan views showing a method for manufacturing an organic EL display device according to a third embodiment of the present invention. In this embodiment, a full-color organic E
4 shows an example of a method for manufacturing an L display device. First, FIG.
As shown in FIG.
After O is sputtered to form an ITO film having a thickness of about 2000 °, the ITO film is patterned into a stripe shape by photolithography to form an anode (lower electrode) 32. In this case, the width of the anode 32 is, for example, 20 μm.

Next, poly [3- (4-alkylphenyl) thiophene] is deposited to a thickness of 1500 ° over the entire display area on the glass substrate 21 by spin coating to form an EL light emitting layer 33. In the present invention, the material of the EL light emitting layer is poly [3- (4-alkylphenyl) described above.
Thiophene], but a polymer whose conjugation length changes by light irradiation is required.

Then, as shown in FIG. 5B, an ArF laser beam is applied to regions other than the red pixel region (R) (ie, the green pixel region (G) and the blue pixel region (B)).
Irradiation is performed under the condition of 000 mJ / cm ² . As a result, the portion of the EL light emitting layer that is not irradiated with the laser emits red light (wavelength: about 650 nm), and the portion of the EL light emitting layer that is irradiated with the laser light has a shorter conjugate length and becomes green (wavelength: about 510 nm).
It emits light. In FIG. 5B, a portion that emits red light in the organic EL layer is indicated by 33R, and a portion that emits green light is indicated by 33G.

Since the relationship between the irradiation intensity of the laser beam and the emission color of the EL light emitting layer differs depending on the material of the EL light emitting layer,
It is necessary to appropriately change the irradiation conditions of the laser beam according to the material. Next, as shown in FIG. 6A, an ArF laser beam was applied to the blue pixel region of the EL light emitting layer at 4000 mJ /.
Irradiate under the condition of cm ² . As a result, the conjugation length of the portion of the EL light emitting layer irradiated with the laser is further shortened, so that the light emitting layer emits blue light (wavelength: about 460 nm). FIG.
In (a), the part of the organic EL layer that emits blue light is 33
It is represented by B.

Next, FIG. 6 (b) is obtained by the lift-off method.
As shown in the figure, a cathode (upper electrode) is provided on the EL light emitting layer 33.
34 are formed. That is, a photoresist is applied to the entire upper surface of the glass substrate 31, and through an exposure and development process,
A window for forming an upper electrode is opened in the resist film. And
After sputtering AlLi to a thickness of 2000 ° on the entire upper surface of the glass substrate 31, the AlLi film on the resist film is removed together with the resist. Thereby, the cathode 34 is formed. The material of the cathode 34 is not limited to the above-described AlLi, and an alkali metal having a small work function or a conductor containing an alkali metal may be used.

In the present embodiment, as described above, RGB light-emitting pixels are formed using a polymer whose conjugate length changes by irradiation with laser light to change the light-emitting color. In other words, since the organic EL element that emits multicolor light can be formed without using a fine processing technique such as dry etching for dividing the organic EL layer 33 for each pixel, the number of manufacturing steps is reduced and the manufacturing cost is reduced. Then, a full-color display EL display device having pixels of three colors RGB is realized.

In the above embodiment, the EL light emitting layer 33 is formed directly on the anode (lower electrode) 32, and the cathode (upper electrode) 34 is formed directly on the EL light emitting layer 33.
Between the anode 32 and the EL light emitting layer 33, and the EL light emitting layer 33
A buffer layer may be formed on at least one of between the upper electrode 34 and the upper electrode 34. In the above embodiment, the method of manufacturing the simple matrix type organic EL display device has been described. However, the present invention can be applied to the manufacture of the active matrix type organic EL display device.

(Supplementary Note 1) In an organic EL device formed by sandwiching an organic EL layer between an anode and a cathode, the cathode includes an alkali metal or an alkaline earth metal and is in contact with the organic EL layer. And Ru (ruthenium), Rh (rhodium), Ir (iridium), Os
An organic EL device having a laminated structure with a second conductive film containing at least one metal selected from the group consisting of (osmium) and Re (rhenium) or an oxide thereof.

(Supplementary Note 2) In an organic EL device formed with an organic EL layer interposed between an anode and a cathode, the cathode includes an alkali metal or an alkaline earth metal and is in contact with the organic EL layer. And a TiN film or Ti
An organic EL device having a laminated structure of a second conductive film composed of a laminated film of N and Ti. (Supplementary Note 3) In an organic EL element formed with an organic EL layer sandwiched between an anode and a cathode, a first conductive film containing an alkali metal or an alkaline earth metal and in contact with the organic EL layer is provided with Ru ( Ruthenium), Rh (rhodium), Ir
A film containing at least one metal selected from the group consisting of (iridium), Os (osmium) and Re (rhenium) or an oxide thereof, a TiN film, or TiN and Ti
An organic EL device having a laminated structure with a second conductive film comprising a laminated film of

(Supplementary Note 4) A step of forming an anode on the substrate, a step of forming an organic EL layer on the anode, and a first step including an alkali metal or an alkaline earth metal on the organic EL layer. Forming a conductive film; and forming Ru (ruthenium), Rh (rhodium), and Ir on the first conductive film.
Forming a second conductive film by depositing at least one metal selected from the group consisting of (iridium), Os (osmium), and Re (rhenium) or an oxide thereof. Of manufacturing an organic EL device.

(Supplementary Note 5) In an organic EL device formed with an organic EL layer interposed between an anode and a cathode, Ru (ruthenium), Mo
An organic EL device comprising at least one metal selected from the group consisting of (molybdenum) and V (vanadium), and having a buffer layer in which only the surface on the organic EL layer side is oxidized.

(Supplementary Note 6) A step of forming an anode on the substrate, a step of forming a buffer layer containing at least one metal selected from the group consisting of Ru, Mo and V on the anode, A surface oxidation step of oxidizing only the surface of the buffer layer, a step of forming an organic EL layer on the buffer layer, and a step of forming a cathode containing an alkali metal or an alkaline earth metal on the organic EL layer A method for producing an organic EL device, comprising:

(Supplementary note 7) The method for producing an organic EL device according to supplementary note 6, wherein the buffer layer is formed to a thickness of 500 ° or less. (Supplementary Note 8) In the surface oxidation step, short-time annealing (Ra
7. The method for manufacturing an organic EL device according to claim 6, wherein only the surface of the buffer layer is oxidized by pid thermal annealing.

(Supplementary note 9) The organic EL device according to Supplementary note 6, wherein in the surface oxidation step, only the surface of the buffer layer is oxidized by any one of laser annealing, plasma oxidation, and anodic oxidation. Production method. (Supplementary Note 10) An organic EL display device in which two or more regions having different emission colors are formed by changing the conjugate length of a polymer constituting the organic EL layer.

(Supplementary Note 11) The organic EL layer according to Supplementary Note 10, wherein the organic EL layer has a red light emitting region, a green light emitting region, and a blue light emitting region having mutually different conjugation lengths.
L display device. (Supplementary Note 12) A step of forming a first electrode on a substrate, a step of forming an organic EL layer made of an organic EL material whose conjugate length changes by light irradiation on the first electrode, A method for manufacturing an organic EL display device, comprising: a step of partially irradiating light to an EL layer to change a conjugate length; and a step of forming a second electrode on the organic EL layer.

(Supplementary note 13) The method for producing an organic EL display device according to supplementary note 12, wherein a polymer that emits red light before irradiation with light is used as a material for the organic EL layer.

[0055]

As described above, the organic EL of the present invention
According to the element, the cathode is formed of a first conductive film containing an alkali metal or an alkaline earth metal, and at least one metal selected from the group consisting of Ru, Rh, Ir, Os and Re or an oxide thereof. Since it has a stacked structure with the second conductive film including the second conductive film, oxidation of an alkali metal or an alkaline earth metal in the first conductive film is prevented, and generation of a dark spot can be avoided for a long time. Further, it can be manufactured by a relatively simple process. TiN as the second conductive film
Similar effects can be obtained when a film or a laminated film of Ti and TiN is used.

According to another organic EL device of the present invention, a buffer layer containing at least one metal selected from the group consisting of Ru, Mo and V is provided between the anode and the organic EL layer. Having only the organic EL layer side surface of the buffer layer,
It is oxidized by a method such as short-time annealing, laser annealing, plasma oxidation, or anodic oxidation. For this reason, even if the unevenness of the surface of the buffer layer is small and the organic EL layer is thin, occurrence of a short circuit or other trouble can be avoided.

Further, since the organic EL display device of the present invention forms regions emitting light of different colors by changing the conjugation length of the polymer constituting the organic EL layer, the organic EL display device of multicolor emission can be easily manufactured. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an organic EL element according to a first embodiment of the present invention.

FIG. 2 is a plan view showing an example of an arrangement of anodes and cathodes of the organic EL device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing an example in which the first embodiment of the present invention is applied to an active matrix type organic EL display device.

FIG. 4 is a sectional view showing a method for manufacturing an organic EL device according to a second embodiment of the present invention.

FIG. 5 is a plan view (part 1) illustrating the method for manufacturing the organic EL display device according to the third embodiment of the present invention.

FIG. 6 is a plan view (part 2) illustrating the method for manufacturing the organic EL display device according to the third embodiment of the present invention.

[Explanation of symbols]

 11, 21, 31 ... glass substrate, 12, 22, 32 ... anode, 13, 24, 33 ... organic EL layer (EL light emitting layer), 14, 25, 34 ... cathode, 14a ... first conductive film, 14b ... Second conductive film, 15: organic EL element, 16: data line, 17: power supply line, 18: scanning line, 19: switch element, 23: buffer layer.

Claims (7)

[Claims] 1. An organic EL device formed by sandwiching an organic EL layer between an anode and a cathode, wherein the cathode includes an alkali metal or an alkaline earth metal, and the first conductive layer contacts the organic EL layer. Film, Ru (ruthenium), Rh (rhodium), Ir (iridium), O
An organic EL device having a stacked structure with a second conductive film containing at least one metal selected from the group consisting of s (osmium) and Re (rhenium) or an oxide thereof. 2. An organic EL device formed by sandwiching an organic EL layer between an anode and a cathode, wherein the cathode includes an alkali metal or an alkaline earth metal, and the first conductive layer contacts the organic EL layer. Film, TiN film,
Alternatively, an organic EL device having a stacked structure of a second conductive film formed of a stacked film of TiN and Ti. 3. a step of forming an anode on a substrate; a step of forming an organic EL layer on the anode; and a first conductive film containing an alkali metal or an alkaline earth metal on the organic EL layer. Forming at least one selected from the group consisting of Ru (ruthenium), Rh (rhodium), Ir (iridium), Os (osmium) and Re (rhenium) on the first conductive film. Forming a second conductive film by depositing a metal or an oxide thereof to form a second conductive film. 4. An organic EL device formed with an organic EL layer sandwiched between an anode and a cathode, wherein Ru (ruthenium), Mo (molybdenum) and V ( An organic EL device comprising at least one metal selected from the group consisting of vanadium) and having a buffer layer in which only the surface on the organic EL layer side is oxidized. 5. A step of forming an anode on a substrate; a step of forming a buffer layer containing at least one metal selected from the group consisting of Ru, Mo and V on the anode; A step of forming an organic EL layer on the buffer layer; and a step of forming a cathode containing an alkali metal or an alkaline earth metal on the organic EL layer. A method for manufacturing an organic EL device, comprising: 6. An organic EL display device wherein two or more regions having different emission colors are formed by changing the conjugate length of a polymer constituting the organic EL layer. 7. a step of forming a first electrode on a substrate; a step of forming an organic EL layer made of an organic EL material whose conjugate length changes by light irradiation on the first electrode; A method for manufacturing an organic EL display device, comprising: a step of partially irradiating light to an organic EL layer to change a conjugate length; and a step of forming a second electrode on the organic EL layer.