JP2002083678A - Method of forming electrode of organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode forming method of effectively carrying out cathode isolation of an organic electroluminescence element, in which an organic substance layer having a prescribed thickness made significantly larger than the conventional ones. SOLUTION: After carrying out film formation of the organic substance layer by thick-film processing, which has at least a pixel luminescence section on a substrate having an anode, regions other than the pixel luminescence section are removed by 25% to 75% with respect to the film thickness of the organic substance layer by high energy beam, such as a laser beam. After that, the cathode isolation of the organic electroluminescence element, having the thick organic substance layer, is performed by carrying out vapor deposition film formation of the metal used as a cathode over the whole surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an electrode of an organic electroluminescence device, and more particularly, to a method for forming an electrode on an organic electroluminescence device applicable to a flat display panel or a backlight. And a method of forming an electrode.

[0002]

2. Description of the Related Art Organic electroluminescent devices are
It is a light emitting element having characteristics such as thinness, all solid type, planar self-luminous property and high-speed response. In the future of the multimedia era, applications to flat display panels and backlights as man-machine interfaces are expected, and research has been actively conducted in various fields in recent years.

[0003] In the past, organic electroluminescent devices were significantly inferior in various characteristics to devices as compared with inorganic electroluminescent devices using inorganic substances.
In 1995, Kodak's Tang et al. Announced a method of forming an organic layer into a laminated structure (CW Tang and S.A.).
A. Vansly ke: Appl. Lett. , 51
After (1987) 913), various characteristics have been rapidly improved.

One of the excellent features of the organic electroluminescence element is that it is thinner than other display elements. That is, in general, each layer of the organic electroluminescence element has a thin film configuration,
The thickness of the parts excluding the substrate is on the order of micrometers or less. Considering the thickness of the substrate, resin, glass, and the like used for the sealing treatment, the overall thickness is on the order of millimeters, and is an extremely thin light-emitting element.

[0005] Further, since the organic electroluminescence element is an all-solid-state element, it is more resistant to shocks than a liquid crystal display which is currently widely used as a thin display panel, and has much vibration as in a car. It can be used as a display device in an environment.

[0006] Further, high speed response is also one of the outstanding features. In general, molecules of an organic electroluminescence element do not move during driving like a liquid crystal,
Since light is emitted only by the action of electrons and holes like a light emitting diode (LED), the response speed is very fast, on the order of tens of nanoseconds. Sufficient driving is possible even with pulse voltage application. The voltage to be applied may be a DC voltage or an AC voltage, but since the organic electroluminescent element has excellent rectification, when an AC voltage is applied,
Light emission can be obtained only when a positive voltage is applied to ITO.

FIG. 1 shows a cross section of an organic electroluminescence element having the most general configuration. An anode 12 is formed on a glass substrate 11. The anode has a work function value of 4 in order to make hole injection advantageous.
eV or more are used.

The anode is often transparent in order to extract light from the light emitting layer sandwiched between the electrodes. Specifically, tin oxide, zinc oxide, indium oxide, ITO (indium tin oxide) and the like are known, and among them, ITO which is excellent in pattern processing is most often used. I
TO is an electron beam method, chemical reaction method,
It is formed to have a predetermined film thickness by a sputtering method or the like, and is further patterned by a photolithography method to be used as an anode of an organic electroluminescence element.

The thickness of the anode is usually appropriately selected from the range of 10 to 1 μm, but it is desirable that the anode has a low resistance in terms of driving the organic electroluminescence element. Specifically, a sheet resistance of 100 Ω / □ or less is used, and a sheet resistance of about 10 Ω / □ is more preferable.

Glass is most frequently used as a substrate in an organic electroluminescence element, but it may be a plastic plate or film of polycarbonate or polyimide, or quartz. However, since a transparent anode is often attached to the substrate, it is desirable that the substrate be transparent in terms of extracting light emission.

An organic material layer 13 is formed on the anode. The organic layer may be composed of only the light-emitting layer. However, in order to improve the characteristics of the device and drive at a low voltage, the charge transport /
In many cases, an injection layer is appropriately inserted, and a stacked structure of these is adopted.

So far, anode / light-emitting layer / cathode, anode /
Hole transport layer / light emitting layer / cathode, anode / hole injection layer / hole transport layer / light emitting layer / cathode, anode / hole transport layer / light emitting layer / electron transport layer / cathode, anode / hole injection layer / hole transport layer / emission 2. Description of the Related Art An organic electroluminescence device having a structure such as layer / electron transport layer / cathode has been manufactured.

In any of the devices having the above structures, the luminescent color obtained depends on the organic compound used for the luminescent layer. In addition, by mixing a very small amount of a fluorescent dye in the light emitting layer (doping), the device characteristics can be further improved, or the emission color can be changed. To date, materials emitting red (R), green (G), and blue (B) have been developed in various fields. Therefore, by appropriately selecting and combining these, light-emitting elements of various colors according to the purpose of use, including full-color display, can be obtained.

The material used for the light-emitting layer of the organic electroluminescence element is not particularly limited, but it is a material in which holes and electrons are injected at the time of applying a voltage, and light is emitted by the recombination thereof. I just need. Specific examples include benzothiazole-based, benzoxazole-based, metal-chelated oxinoid compounds, styrylbenzene-based, oxadiazole derivatives, and metal complexes.

The material used for the hole injection layer and the hole transport layer is not particularly limited, but preferably has a high hole transport ability. In addition, it is desirable to be able to block the electron injection from the viewpoint of improving the luminous efficiency of the organic electroluminescence element. Specific examples include triphenylamines, imidazole derivatives, pyrazoline derivatives, oxadiazole derivatives, and complex compounds such as phthalocyanine derivatives.

The material used for the electron transporting layer is not particularly limited, but preferably has a high electron transporting ability. Specifically, there are tris (8-quinolinol) aluminum, diphenylquinone derivatives and the like.

The thickness of these organic layers is from 50 ° to 5 °.
μm is selected as appropriate, but in most cases, from 50 to 5000 in view of the driving voltage of the device and the stability of the organic material layer.
The thickness is often Å. As a film forming method, a vacuum deposition method, a spin coating method, a casting method, an LB method, an ink jet method, and the like can be applied. At present, a method of forming a film by a vacuum deposition method or a spin coating method is the most widespread. Has been adopted.

A cathode 14 is formed on the organic material layer. In most cases, a metal is used as the cathode, and a metal or alloy having a small work function, such as aluminum, indium, magnesium, silver, or an alloy of magnesium and silver, in order to make electron injection into the organic material layer advantageous. It is desirable to use an alloy of aluminum and lithium.

However, although a metal having a small work function is advantageous with respect to electron injection, it is easily oxidized in the air and loses its function as an electron injection electrode. In many cases, the outside of a small metal is covered with a metal having a large work function so that the metal having a small work function does not come into contact with the outside world or is alloyed.

As a film forming method for using these metals for the cathode, there are a resistance heating evaporation method, an electron beam evaporation method and a sputtering method. The thickness of the cathode is also appropriately selected from 50 ° to 5 μm, but it is desirable to make the resistance as low as possible in order to enhance the characteristics of the organic electroluminescence device.

Further, in most cases, the element portion is covered with a sealing material 15 to ensure reliability. Sealing is performed so that oxygen and moisture do not enter the inside of the organic electroluminescence element. Regarding a sealing method, a method of hollow sealing with a glass or metal lid, a method of sealing the upper part of the element with a resin, and the like have been proposed.

In an organic electroluminescence element, the entire light emitting layer sandwiched between an anode and a cathode emits planar light, and the light emitting area is not limited. Therefore, it can be used for a backlight such as a liquid crystal display. Further, the emission color can be freely determined depending on the material used for the emission layer or the material doped in the emission layer.

In the organic electroluminescence device shown in FIG. 1, when a voltage is applied, the transparent substrate 1
1 and the anode 12, the light emission 16 from the light emitting layer of the organic material layer 13 is obtained.

[0024]

When an organic electroluminescence device having these excellent features is actually manufactured, it is important to ensure the reliability of the device.

It is essential to prevent a leak current among the problems related to ensuring the reliability of the element. In general, an organic electroluminescent element in a good state exhibits characteristics of a rectification ratio of about 10 ^5, but when a leak current occurs, the rectification ratio is greatly reduced. The leakage current causes heat generation, and easily destroys an organic electroluminescence element using an organic substance which is weak to heat. Further, when a display panel is manufactured using an organic electroluminescence element, the presence of a leak current causes crosstalk, which is a fatal defect for the display panel.

The leak current is generated for several reasons.

First, the first cause is caused by the organic material used for the device. That is, as shown in FIG. 2, the organic material layer 23 of the organic electroluminescence element generates a film defect called a pinhole 25 in the film due to crystallization of the organic material or the like.
1 and the cathode 24 may be short-circuited and a leak current may occur.

The second cause of the leak current is as follows.
There is a problem of dust adhesion in the element manufacturing process. That is, since the organic electroluminescence element has a structure in which thin films having a thickness of 1 μm or less are stacked, extremely minute dust greatly affects the element. As shown in FIG. 3, when dust 35 is mixed in the element, a uniform organic material layer 33 is not formed, which causes a leak current.

The third cause of the leak current is as follows.
In the vicinity of the edge of the pixel, particularly in the vicinity of the anode edge, there is a case where the organic material layer becomes thinner than a predetermined thickness. That is, as shown in FIG. 4, when the film thickness of the organic material layer 43 is not uniform in the pixel light emitting portion, current concentrates on a portion where the organic material layer 43 is thinner than the others, resulting in a leak current. appear.

That is, the problem of the generation of a leak current in the organic electroluminescence element is caused by the organic layer. Originally, one of the outstanding characteristics of an organic electroluminescence element is that it is thin. However, the above problem is caused by the fact that the organic material layer has a thickness of about 50 to 5000 ° in many cases. I can say.

Considering that the thickness of a liquid crystal display which is currently widely used as a thin display panel is on the order of mm, when an organic electroluminescent element is put into practical use, the thickness of the organic material layer is not as large as that of the present. It need not be as thin as 50-5000 °. As long as the thickness of the organic material layer is not increased to the order of cm, the excellent characteristic of the organic electroluminescent element being thin is not lost at a practical level.

At present, the thickness of the organic layer of the organic electroluminescent device which is being researched and developed in various fields is 50 to 50%.
The reason that the angle is about 5000 ° is due to the characteristics of the organic material used for the device. The organic electroluminescent element can emit light by passing a current through an organic substance, but requires a strong electric field of about 10 ⁶ V / cm to pass a current through the organic substance. Therefore, when the thickness of the organic material layer is greatly increased, the device driving voltage is increased, so that the thickness is inevitably reduced to 50 to 5000 °.

Because of the current thinness of 50 to 5000 °, reliability such as generation of pinholes in the organic thin film, adhesion of fine dust mixed in the element, and nonuniformity of the film thickness near the electrode edge is considered. Problem arises. When a leak current occurs, crosstalk occurs when a display panel using an organic electroluminescence element as a light emitting element is produced, which has a fatal effect.

Therefore, in practical use of an organic electroluminescence device in the future, it can be said that it is effective to greatly increase the thickness of the organic material layer in order to improve yield and reliability.

For example, if the thickness of the organic material layer is 100 μm, which is about 1000 times greater than the current state, the occurrence of pinholes in the organic material layer can be prevented. FIG.
As shown in (2), even if the fine dust 55 adheres to the element, short circuit hardly occurs because the organic material layer 53 is sufficiently thick, and the element leakage is greatly reduced. Furthermore, the problem of non-uniformity of the film thickness near the electrode edge can be neglected because of the thick film, and the problem for practical use is greatly improved.

However, there are many problems to greatly increase the thickness of the organic material layer. First, even if the thickness of the organic material layer is increased, an increase in the element driving voltage must be suppressed. For that purpose, it is necessary to lower the resistance value of the organic material layer. Currently used organic materials have a carrier mobility of 1
Since it is about 0 ^-7 to 10 ^-3 cm ² / V _S, it is conceivable to develop an organic material having a higher mobility or to mix an inorganic material with the current material. This is not enough and will remain as a future task. In addition, as for a film forming method, in a vacuum evaporation method and a spin coating method which are often used at present, since many materials are wasted without being attached to an element portion, an ink jet method or a roll coating method is preferable in terms of cost. I think that the.

On the other hand, in order to manufacture an organic electroluminescent device having a thicker organic material layer than the present condition (hereinafter referred to as “thick film type organic electroluminescent device”), in addition to the device driving voltage, the present invention Another problem arises from the organic electroluminescent device (hereinafter referred to as “thin film type organic electroluminescent device”).

The most important issue to consider in the thick-film type organic electroluminescence device is a method of separating the cathode on the organic material layer. Cathode separation is also a major technical problem in thin-film type organic electroluminescence devices, and various methods have been proposed.

For example, Japanese Patent Application Laid-Open No. 8-315981 discloses a method in which an insulating reverse tapered structure having a height of several μm to several tens μm is provided on a substrate with electrodes, and then a metal used as a cathode is deposited. Has been proposed. Also, in Japanese Patent Application Laid-Open No. 5-275172, a height of several μm to several tens μm is provided in a substrate with electrodes in parallel with the anode pattern.
A method has been proposed in which a metal to be used as a cathode is deposited obliquely on a substrate after the insulating structure is installed, and the cathode is separated using the shadow of the insulating structure.

That is, in any case, by placing some structure on the substrate with the anode before forming the organic material layer, and utilizing the shadow of the structure when forming the electrode on the organic material layer,
Electrodes are separated. In any of the methods, a structure is placed on a substrate with an anode before forming an organic material layer.
This is due to the durability of the organic matter. It is difficult to install any structure on the organic material layer after the organic material film formation in consideration of the durability of the organic material to moisture and an organic solvent, and this is because a conventional wet process cannot be used.

However, in order to separate the electrodes on the organic material layer, a method of installing an insulating structure on a substrate with electrodes is as follows.
Although it is very effective in a thin film type organic electroluminescence device, it cannot be used in a thick film type organic electroluminescence device.

That is, when the thickness of the organic material layer is greatly increased, the structure on the substrate with the anode is hidden by the organic material layer. The height of the insulating structure used for the cathode separation is about several μm to several tens μm. If the height is set higher than this, the structure may fall down in consideration of the fact that the width of the structure is about 30 μm. Therefore, when the thickness of the organic material layer becomes 1 μm or more, the insulating structure is buried in the thick organic material layer, and the cathode cannot be separated.

In the past, a method using a shadow mask has been used for the cathode separation of a thin film type organic electroluminescence element, and a method of applying this method to a thick film type organic electroluminescence element can be considered.

However, a method using a shadow mask is as follows.
Deflection due to mask positioning accuracy and processing accuracy, or the weight of the shadow mask itself, has remained a difficult problem even in the production of thin-film type organic electroluminescence devices. In addition, if a shadow mask is placed in a state where a relatively soft organic material layer is formed thick, the organic material layer may be damaged, and it becomes more difficult to apply the organic material layer to a thick-film type organic electroluminescence device. Therefore, it can be said that the method of using the shadow mask for the thick film type organic electroluminescence element is a difficult method in actual manufacturing.

[0045]

According to the present invention, there is provided a method for forming an electrode of an organic electroluminescence device having at least an anode, an organic material layer having a pixel light emitting portion, and a cathode on a transparent substrate. An organic material layer of a predetermined thickness whose film thickness is significantly thicker than before is formed, and then,
Using a high-energy beam, the organic material layer other than the pixel light emitting portion is removed in parallel with the cathode line pattern and 25% to 75% of the film thickness of the organic material layer to form a groove for cathode separation. Subsequently, there is provided a method for forming an electrode of an organic electroluminescence element, wherein a metal as a cathode is deposited on the entire surface of the organic material layer.

That is, we believe that it is effective to increase the thickness of the organic material layer in order to improve the productivity by practically using the organic electroluminescence element widely in the future. The present inventors thought that it was essential to solve the technical problem of reliably separating the cathode of the present invention, and completed the present invention. More specifically, as a method of forming an organic material layer having a predetermined thickness (for example, 1 μm to 100 μm) which is much larger than the conventional case, and separating the cathode, a predetermined width is applied to the organic material layers other than the pixel light emitting portion. Forming a groove (for example, 1 μm to 10 μm),
The inventors have invented a method of using this groove for cathode separation. The organic material layer has a width of about 10 μm and a depth of 1 μm.
For example, an excimer laser is used in order to perform high-level processing of about m.

An excimer laser is an ultraviolet laser that uses a rare gas and halogen excitons and oscillates only in pulses. The oscillation wavelength is determined by the combination of gases,
ArF: 193 nm, KrF: 248 nm, XeCl:
308 nm.

Excimer lasers include YAG lasers and C
It does not use a thermal processing process using an infrared laser such as an O ₂ laser, but uses a photochemical phenomenon. When excimer laser light is irradiated, the irradiated part instantaneously decomposes and scatters (ablation). Finer processing is possible than infrared lasers.

In order to process an organic substance by using an excimer laser, it is only necessary to consider parameters such as the absorption coefficient of the organic substance, the oscillation laser wavelength, and the irradiation energy density (fluence). The processing fine precision of the excimer laser is several μm, and the reproduction precision of the processed shape is 1 μm or less. In addition, since processing is performed at a submicron depth for each pulse, control in the depth direction is easy.

Therefore, in an organic electroluminescent device having a sufficiently thick organic material layer, it is possible to form a groove for cathode separation in a region other than the pixel light emitting portion by determining appropriate excimer laser irradiation conditions. You can.

After a groove is formed in the organic material layer by an excimer laser and a metal to be used as a cathode is vapor-deposited on the entire surface of the organic material layer, the vapor-deposited surface of aluminum is divided by the groove to perform cathode separation.

Here, a groove for cathode separation is formed by removing an organic material layer other than the pixel light emitting portion by 25% to 75% with respect to its film thickness using a high energy beam such as an excimer laser. If it is less than 25%, the cathode separation will not be sufficiently performed, and if it exceeds 75%, the time and cost for forming the groove will increase unnecessarily.

In the electrode forming method according to the present invention, the thickness of the organic material layer is preferably 1 μm to 100 μm. This is because when the film thickness of the organic material layer is less than 1 μm, the effect of improving the yield and reliability of the organic electroluminescence device hardly appears, while when the film thickness of the organic material layer exceeds 100 μm, the organic electroluminescence device does not. This is because the manufacturing cost of the device increases unnecessarily.

In the electrode forming method according to the present invention, it is preferable that the removal of the organic material layer other than the pixel light emitting portion does not show the anode under the material layer. This is because when the organic material layer is removed at a rate of 25% to 75% with respect to its thickness, if the underlying anode appears, a short circuit may occur between the upper and lower electrodes, and the cathode can be separated. Because it is gone.

In the electrode forming method according to the present invention, the width of the groove formed in the organic material layer by the high energy beam is 1 μm.
m to 10 μm. This means that the width of the groove is 1
When the width is less than μm, the effect of the cathode separation hardly appears. On the other hand, when the width exceeds 10 μm, the time and cost for forming the groove are unnecessarily increased.

[0056]

Embodiments of the present invention will be described below with reference to the drawings. The following contents are merely examples, and do not particularly limit the present invention. Further, it should be noted that the light-emitting characteristics of the thick-film type organic electroluminescent device are insufficient at present and that improvement of the organic material is required.

Example 1 A commercially available borosilicate glass substrate 41 having a thickness of 1.1 mm with an ITO conductive film manufactured by Sanyo Vacuum Co., Ltd. was subjected to ultrasonic cleaning with isopropanol for 3 minutes, followed by vapor cleaning. Minutes. In addition, IT
The thickness of O was 1600 ° as measured by a stylus type thickness gauge, and the ITO surface was flat with little unevenness.
The sheet resistance was 20Ω / □.

Subsequently, the ITO is etched by a well-known general photolithography method to have a width of 15 mm.
An anode pattern of ITO having a thickness of 0 μm and a line pattern of 30 μm was formed, and cut into a size of 30 mm × 30 mm to obtain a substrate with an anode for an organic electroluminescence element.

Subsequently, by a well-known general photolithography method and a sputtering method, nickel as an auxiliary electrode is applied to only the wiring portion connecting the pixels with 1500.
The film was formed to have a thickness of Å. At this time, nickel was not formed on the 150 μm × 150 μm portion serving as the anode pixel light emitting portion, and the ITO was exposed to the surface as it was.

The ITO has a higher resistivity than the metal used for the cathode, and when a fine pattern of 100 μm or less is used as in the case of manufacturing a display panel using an organic electroluminescent element, a voltage drop due to the wiring resistance occurs only with the ITO. Therefore, it is necessary to provide an auxiliary electrode. As a precautionary measure, the resistance before and after the formation of nickel was measured. The resistance was 1 kΩ in the case of the pattern of only ITO without the formation of nickel, but the resistance was 200 kΩ by forming the nickel. Reduced to This confirmed that nickel functions as an auxiliary electrode.

Subsequently, ultrasonic cleaning was performed with pure water and isopropanol for 3 minutes, and vapor cleaning with isopropanol was performed for 5 minutes to clean the surface of the substrate anode.

Subsequently, the substrate with the anode was subjected to UV ozone irradiation treatment. Immediately after washing the ITO glass substrate, irradiation was performed for 5 minutes to remove residual organic components on the anode surface.

Subsequently, an organic layer of the thick-film type organic electroluminescence device was formed by a well-known spin coating method. For the organic material layer, poly N-vinyl carbazole having a hole transporting property was used. In order to make the film thickness much larger than usual, the number of revolutions during spin coating was greatly reduced. When the film thickness was confirmed with a stylus meter, it was 10 μm, and it was confirmed that the condition was an organic material layer of a thick film type organic electroluminescence device.

Subsequently, a groove for cathode separation was formed in the thick organic material layer. That is, KrF having an oscillation wavelength of 248 m
The organic material layer was removed by irradiating an excimer laser so as not to impinge on the pixel light emitting portion and in a pattern perpendicular to the anode ITO.

In order to form a groove on the organic material layer, it is necessary to greatly reduce the laser intensity. We set the oscillation pulse repetition rate to 10 Hz or less and the pulse energy to 10 m.
J or less. In this embodiment, the number of irradiation shots is set in advance so that a groove is formed at a depth of 50% of the organic material layer. The thickness of the organic layer is 10
μm, it means that a groove having a depth of 5 μm was formed.

Subsequently, the substrate was transferred to an electrode deposition chamber of a resistance heating type vapor deposition machine, and an aluminum-lithium alloy used as a cathode was vapor-deposited at 1500 ° C. at a degree of vacuum higher than 1 × 10 ⁻⁶ torr. At this time, no shadow mask was set between the evaporation source and the substrate, and the entire surface including the pixel light emitting portion was evaporated.

Subsequently, a sealing process was performed to prevent the element from being deteriorated by moisture and oxygen in the atmosphere. The substrate, which has been vapor-deposited up to the cathode aluminum, is transferred from the electrode deposition chamber to the sealing glove box, and the glass having the hollow structure is bonded using a UV-curable polymer resin and cured by UV irradiation to form a hollow seal. I stopped it. Illustration of the sealing process is omitted.

By the above steps, the size of 100 μm × 1
A thick-film type organic electroluminescent device in which 00 μm light-emitting pixels are arranged in a matrix was completed.
In this organic electroluminescence element, as shown in FIG. 5, even if the fine dust 55 adheres to the element, the organic substance layer 53 is sufficiently thick, so that a short circuit is unlikely to occur, and the element leakage is greatly reduced. did.

Comparative Example 1 The same procedure as in Example 1 was carried out until an organic material layer was formed which was much thicker than usual. A YAG laser was used as a technique for forming a groove for separating the cathode in the organic material layer. Subsequently, in the same manner as in Example 1, aluminum was deposited as a cathode,
A sealing treatment was performed, and this was designated as Comparative Example 1.

Unlike an excimer laser, a YAG laser has an oscillation wavelength in the infrared region. Therefore,
When the organic layer is irradiated with a YAG laser, thermal processing is performed.

Comparative Example 2 For forming an organic material layer much larger than usual and forming grooves in the organic material layer, a KrF excimer laser was used as in Example 1, but the laser irradiation time was increased. A groove was formed until the surface of the anode of ITO appeared, that is, 100% of the organic material layer was removed. Subsequently, in the same manner as in Example 1, aluminum was vapor-deposited as a cathode and sealing treatment was performed.

Comparative Example 3 The KrF excimer laser was used in the same manner as in Example 1 for forming an organic material layer much thicker than usual and forming a groove in the organic material layer. That is, a groove was formed by removing 10% of the organic material layer. That is, a groove having a depth of 1 μm was formed in the organic layer having a thickness of 10 μm. Subsequently, in the same manner as in Example 1, aluminum as a cathode was vapor-deposited and sealed, and this was designated as Comparative Example 3.

Comparative Example 4 Example 1 was repeated except that the thickness of the organic material layer was set to 5000 ° which is about the same level as that of a conventional thin film type organic electroluminescence device.
Similarly to the above, grooves were formed in the organic material layer using a KrF excimer laser. Excimer laser irradiation time was shorter than that of Comparative Example 3. This was designated as Comparative Example 4.

Next, it was confirmed by using a tester whether or not the cathodes of the thick-film type organic electroluminescent devices manufactured in Example 1 and Comparative Examples 1 to 3 were separated.

Then, in the thick-film type organic electroluminescence device of Example 1, the separation state of the cathode on the organic material layer was confirmed, and it was found that the cathode was separated into a line pattern by the groove formed in the organic material layer.

When the dimensions of the groove formed in the organic material layer were measured, the width was 5 ± 0.5 μm and the depth was 5 ± 0.5 μm, indicating that processing using an excimer laser was effective for forming the groove. I understood. Further, since the thickness of the organic material layer was 10 μm, the anode surface did not appear even by excimer laser irradiation, and the influence of the short circuit was not observed.

In Comparative Example 1, the cathode was not separated by the groove. When confirmed by a microscope, it was found that the periphery of the groove processing portion had once melted, and that thermal processing with a YAG laser was insufficient.

In Comparative Example 2, although the cathode was separated, a point where a short circuit occurred between the anode and ITO was observed.

In Comparative Example 3, the grooves on the organic material layer were shallow, and the cathode separation was insufficient.

In Comparative Example 4, the organic material layer was removed by excimer laser irradiation until the ITO of the anode appeared, and a short circuit occurred with the anode as in Comparative Example 2.

No light emission was observed in any of the thick-film type organic electroluminescent devices because of the large thickness of the organic material layer and the characteristics of the organic material used.

In the thick-film type organic electroluminescence device of Example 1, it was found that it is very effective to remove organic substances other than the pixel light-emitting portion with an excimer laser as a method of separating the cathode on the organic substance layer. . The cathode deposition conditions are described in JP-A-5-275172.
It is also possible to set a substrate such as that used in the figure in an oblique direction with respect to the evaporation source.

[0083]

According to the method for forming an electrode of an organic electroluminescence device according to the present invention, an electrode of an organic electroluminescence device having at least an anode, an organic layer having a pixel light-emitting portion, and a cathode on a transparent substrate is provided. In the formation method, an organic material layer having a predetermined thickness in which the film thickness of the organic material layer is significantly thicker than before is formed, and then, using a high-energy beam, the organic material layers other than the pixel light emitting portion are formed with a cathode line pattern. A groove for cathode separation is formed so as to be parallel and removed by 25% to 75% with respect to the film thickness of the organic material layer, and subsequently, a metal as a cathode is deposited on the entire surface of the organic material layer. I do. Therefore, in the organic electroluminescent device obtained by this method,
Cathode separation is effectively performed by dividing the metal deposition surface by the groove.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thin film type organic electroluminescence device having the most general configuration in the related art.

FIG. 2 is a diagram schematically showing a state in which an organic material layer is crystallized in a conventional thin-film type organic electroluminescence device.

FIG. 3 is a diagram schematically showing a state in which minute dust is mixed in the conventional thin film type organic electroluminescence device.

FIG. 4 is a diagram schematically showing a state in which a thin organic layer is formed near a pixel edge in a conventional thin film type organic electroluminescence device.

FIG. 5 is a diagram schematically showing a state in which a leak current hardly occurs even if minute dust is mixed in the thick film type organic electroluminescence device according to the embodiment of the present invention. is there.

Claims (5)

[Claims] 1. A method for forming an electrode of an organic electroluminescence element having at least an anode, an organic material layer having a pixel light-emitting portion, and a cathode on a transparent substrate, wherein the thickness of the organic material layer is much larger than before. An organic layer having a predetermined thickness is formed, and then, using a high energy beam,
The organic material layer other than the pixel light emitting portion is set to be parallel to the cathode line pattern and 25% to 7% with respect to the thickness of the organic material layer.
A method for forming an electrode of an organic electroluminescent device, comprising removing 5% to form a groove for cathode separation, and subsequently depositing a metal as a cathode on the entire surface of the organic material layer. 2. The method according to claim 1, wherein excimer laser is used as the high energy beam. 3. The organic layer has a thickness of 1 μm to 100 μm.
The method for forming an electrode of an organic electroluminescence device according to claim 1, wherein 4. The method for forming an electrode of an organic electroluminescence device according to claim 1, wherein the removal of the organic material layer other than the pixel light emitting portion does not show the anode underlying the device layer. 5. The method for forming an electrode of an organic electroluminescence device according to claim 1, wherein the width of the groove formed in the organic material layer with a high energy beam is 1 μm to 10 μm.