JP2000036391A - Organic electroluminescent element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve characteristics and durability while lowering the resistance in a second electrode so as to reduce unevenness of luminance, heating, power consumption and a load to a drive circuit by electrically connecting a guide electrode to the second electrode in a predetermined form. SOLUTION: A first electrode 2 made of excellent conductive transparent material such as tin oxide is formed on a substrate 1a, and plural insulating projections 3 having a desirable shape formed with a conductive part on the surface thereof are provided by patterning on the substrate 1a except for the part provided with the first electrode 2, and thereafter, a thin film layer 10 including a light emitting layer is formed. The projections 3 are formed higher than the thickness of the thin film layer 10. A second electrode 8 made of platinum and aluminum is formed into a stripe by make deposition method so as to cover the surface of the projections 3, and the second electrode 8 is electrically connected to a guide electrode 4 formed in a substrate 1b so as to follow the shape of the light emitting element and having 2 KΩ/m or less of resistance value through the projections 3. The substrates 1a, 1b are adhered to each other so as to seal the light emitting element, and deterioration of the light emitting characteristic due to the moisture and oxygen is thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device that can be used in fields such as display devices, flat panel displays, backlights, and interiors, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, an organic electroluminescent device has attracted attention as a new light emitting device. This element emits light by the recombination of the holes injected from the anode and the electrons injected from the cathode in the organic light emitting layer sandwiched between both electrodes,
It is possible to emit light with high luminance at a low voltage by C.D. W.
Tang et al. (Appl. Phy.
s. Lett. 51 (12) 21, p. 913,198
7).

FIG. 20 is a sectional view showing a typical structure of an organic electroluminescent device. On a transparent first electrode (anode) 2 formed on a glass substrate 1, a hole transport layer 5, an organic light emitting layer 6,
The second electrode (cathode) 8 is stacked, and light emitted by driving by the driving source 9 is extracted to the outside through the first electrode and the glass substrate. Such an organic electroluminescent device is thin,
High luminance light emission under low voltage driving and multi-color light emission by selecting an organic light emitting material are possible, and application to a light emitting device such as a display element or a display is actively studied.

FIGS. 21 to 23 show the structure of a simple matrix type color display using an organic electroluminescent device.
A first electrode 2 and a second electrode 8 in the form of stripes orthogonal to each other
A pixel is formed by an organic electroluminescent element at the intersection with. A pattern or image can be displayed by applying a voltage to a desired pixel to emit light.However, a current required for light emission is supplied to each pixel through each electrode. Occurs. In particular, in a simple matrix type display, as the size increases, the electrodes become longer, and as the duty ratio decreases, the current flowing instantaneously increases, so that the voltage drop increases. This is particularly noticeable in scan lines where more current is concentrated.

In a light emitting device using an organic electroluminescent element as well as a simple matrix type, the above-described voltage drop increases unnecessary power consumption and a load on a driving circuit, and also causes deterioration of durability due to heat generation. . Therefore, the electric resistance of each electrode is preferably small.

As a technique for lowering the resistance of the second electrode, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 4-6795 is disclosed. A conductive thin film is laminated on the second electrode and functions as a guide electrode to reduce the resistance. It is trying to make it. Also, Japanese Patent Application Laid-Open No.
In the technique disclosed in Japanese Patent No. 1186, an electrode is formed by applying a polymer solution containing conductive fine particles, and it is relatively easy to increase the thickness of the electrode.

[0007]

However, a conventional electrode having a laminated structure cannot sufficiently reduce the resistance. In order to perform patterning by a dry process, the second electrode is often formed by a vacuum deposition method. However, in this case, it takes a long time to form a thick electrode. There is a problem that the process time increases and the process is susceptible to thermal effects during the process, and it has been substantially difficult to lower the resistance of the electrode.

On the other hand, if the second electrode is formed by a coating method, it is easy to increase the thickness of the electrode. However, since the wet process is used, the organic thin film layer having poor durability against moisture, organic solvents, and chemicals is damaged. And significantly reduces the performance of the organic electroluminescent device. Therefore, there is a problem that the material used for the organic electroluminescent element is limited.

The present invention solves such a problem and provides an organic electroluminescent device and a method of manufacturing the same, which reduce the resistance of the second electrode to reduce uneven brightness, calorific value, power consumption, and load on a driving circuit. That is the purpose.

[0010]

According to the present invention, there is provided an organic electroluminescent device comprising: a first electrode formed on a substrate; and a thin film layer including at least a light emitting layer made of an organic compound and formed on the first electrode. An organic electroluminescent device having a second electrode formed on the thin film layer and having a plurality of light emitting regions on the substrate, wherein at least a portion has a height exceeding the thickness of the thin film layer A protrusion is formed on the substrate, and the second electrode is electrically connected to a guide electrode existing outside the second electrode via the protrusion.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an organic electroluminescent device of the present invention and a method of manufacturing the same will be described. However, the present invention is not limited to the organic electroluminescent device having the exemplified form and structure and a method of manufacturing the same. . Therefore, the present invention can be applied to any type of light emitting device such as a single light emitting element, a segment type, a simple matrix type, and an active matrix type, and an organic electroluminescent element of any structure regardless of the number of emission colors such as color and monochrome. It is.

An example of the organic electroluminescent device of the present invention is shown in FIGS.
As shown in FIG. A striped first electrode 2 formed on a substrate 1a, a thin film layer 10 including a light emitting layer 6 made of an organic compound patterned on each first electrode, and a striped stripe orthogonal to the first electrode; The second electrode 8 is stacked, and a plurality of light emitting regions having an organic electroluminescent element structure are formed at intersections of the two electrodes. Each light-emitting region emits red (R), green (G), and blue (B) light by using different materials for the light-emitting layer. Therefore, by driving these simple matrix light-emitting elements line-sequentially, an image or the like is displayed in color. It is possible to

In this light emitting device, a projection 3 having a height exceeding the thickness of the thin film layer 10 is formed on the substrate 1a. On the other hand, a guide electrode 4 is patterned on another substrate 1b in advance. Since the second electrode 8 is electrically connected to the guide electrode 4 via the protrusion 3, the second electrode 8 can be relatively easily formed without damaging the element portion due to the guide electrode directly contacting the light emitting region. Can be reduced. Hereinafter, the organic electroluminescent device of the present invention and a method for manufacturing the same will be described in detail by taking this structure as an example.

The first electrode and the second electrode serve to supply a sufficient current for light emission of the device.
Preferably, at least one of them is transparent to extract light. Usually, the first electrode formed on the substrate is a transparent electrode, and this is an anode.

As the transparent electrode material, indium, tin,
It is often made of at least one element selected from gold, silver, zinc, aluminum, chromium, nickel, vanadium, molybdenum, and rubidium or an oxide thereof, but inorganic conductive substances such as copper iodide and copper sulfide, and polythiophene It is also possible to use conductive polymers such as polypyrrole and polyaniline. Preferred transparent electrode materials include tin oxide, zinc oxide, indium oxide, indium tin oxide (hereinafter ITO), and the like.
For the purpose of patterning, ITO with excellent workability
Is preferably used for the transparent electrode.

In the step of patterning the first electrode, a photolithography method involving etching can be used. The pattern shape of the first electrode is not particularly limited, and an optimum pattern may be selected depending on the application. In the present invention, it is preferable to perform patterning on a plurality of stripe-shaped electrodes arranged at predetermined intervals.

In order to improve conductivity, ITO may contain a small amount of metal such as silver or gold.
Silver, zinc, indium, aluminum, chromium, titanium, and nickel can also be used as ITO guide electrodes. In particular, chromium is a suitable metal because it can have both functions of a black matrix and a guide electrode. From the viewpoint of element power consumption,
ITO preferably has a low resistance. For example, 300
An ITO substrate of Ω / □ or less (a transparent substrate on which an ITO thin film is formed) functions as a device electrode.
It is particularly preferable to use a low-resistance product because an ITO substrate of Ω / □ or less can be supplied. ITO
Can be selected according to the resistance value, but is usually 100 to 300 nm. The method of forming the ITO film is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

The transparent electrode has no major obstacle to its use if the visible light transmittance is 30% or more, but ideally 100%.
% Is preferred. Basically, it is preferable to have the same transmittance in the entire visible light range. However, when it is desired to change the emission color, it is possible to positively impart light absorbency. In such a case, it is technically easy to change the color using a color filter or an interference filter.

The material of the transparent substrate is not particularly limited, and a plastic plate or film made of polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polyimide, or aramid can be used, but a glass plate is most preferable. As for the material of the glass, non-alkali glass, soda lime glass coated with a barrier coat such as a silicon oxide film, or the like can be used. Since the thickness only needs to be sufficient to maintain mechanical strength, 0.5
mm or more is sufficient.

One of the features of the present invention is to provide a projection having a height at least partially exceeding the thickness of the thin film layer on the substrate on which the first electrode is patterned. The planar shape of the projection can be any shape such as a polygon or a circle.
Therefore, the stripe-shaped projections 3 may be formed between the first electrodes 2 as shown in FIGS. 1 to 3, or the first electrodes 2 may be exposed in a lattice shape as shown in FIG. Matrix-shaped projections 3 may be formed. Further, as shown in FIG. 5, a plurality of dot-shaped projections can be arranged. The cross-sectional shape is also not particularly limited, but is preferably tapered to facilitate electrical connection with the guide electrode. The height of the projection is preferably higher for the same reason, but is usually selected in the range of 1 to 100 μm in order to form the projection stably.

The position on the substrate where the projection is formed may be a portion where the first electrode 2 exists, as shown in FIGS. However, when the projection is formed on the first electrode, the portion does not function as the organic electroluminescent element, and as a result, the area of the light emitting region is reduced. Therefore, protrusion 3
Is preferably located in a region where the first electrode 2 does not exist. Also, as shown in FIGS. 1 to 4, if the protrusion 3 is positioned so as to cover the edge of the first electrode 2, a short circuit between the first electrode 2 and the second electrode 8 can be prevented and the organic electroluminescent element can be formed. Can be stabilized.

The size, number, and arrangement of the projections are not particularly limited, and an optimum one may be selected according to the shape of the light emitting region, the second electrode, the guide electrode, and the like. Further, the projection is preferably formed by one layer, but may have a laminated structure composed of a plurality of layers in some cases. For example, it is also possible to first form a first layer functioning as an edge protective layer or a black matrix in a shape that exposes the stripe-shaped first electrode in a lattice shape, and then form a projection thereon. In this case, the protrusion has a laminated structure of two or more layers.

As described above, the protrusion is preferably made of an insulating material because the protrusion is located at the center of the region where the first electrode does not exist, that is, so as to straddle between the electrically independent first electrodes. As such materials, known materials such as oxides, glasses, and ceramics are used for inorganic materials, and polyvinyls, polyimides, polystyrenes, acrylics, and novolaks are used for organic materials.
Known polymer resin materials such as silicon-based materials can be used.

Furthermore, it is preferable that at least a part of the projection is black. As a result, light absorptivity is exhibited in the non-light emitting region, so that the external light reflectance is reduced, and an effect such as improvement in contrast is obtained. Preferred black projection materials include inorganic materials such as silicon, gallium arsenide, manganese dioxide, titanium oxide, and a laminated film of chromium oxide and metal chromium. Organic materials include carbon black, phthalocyanine, anthraquinone, monoazo, and metal. Known pigments and dyes, such as complex-type monoazo, disazo, triallylmethane, and aniline-based pigments, or the above-mentioned black inorganic material powder mixed with the polymer resin material can be used.

In the step of patterning the protrusions, a photolithography method, a dry etching method, a mask evaporation method,
Known techniques such as a screen printing method, a sand blast method, and a nozzle coating method can be used. In particular, it is preferable to form the projections using a known photosensitive resin material used for applications such as formation of a photoresist or a protective film.

In the present invention, after the projections are formed, a thin film layer including at least a light emitting layer made of an organic compound is formed on the first electrode. The thin film layers included in the organic electroluminescent device include 1) a hole transport layer / a light emitting layer, and 2) a hole transport layer /
The light-emitting layer / electron transport layer, 3) the light-emitting layer / electron transport layer, and 4) a light-emitting layer in which at least one of the layer constituent materials is mixed may be used. That is, if a light-emitting layer made of an organic compound is present as an element configuration, a light-emitting material alone or a light-emitting material and a hole-transport material or an electron-transport, as described in 4), in addition to the multi-layer structure of 1) to 3) above. Only one light-emitting layer containing a material may be provided.

The hole transporting layer is formed of a hole transporting material alone or a hole transporting material and a polymer binder. As a hole transport material, N, N′-diphenyl-N, N′-di (3-methylphenyl) -1,1 ′ is used for a low molecular weight compound.
-Diphenyl-4,4'-diamine (TPD), N,
N'-diphenyl-N, N'-dinaphthyl-1,1'-
Heterocycles represented by triphenylamines represented by diphenyl-4,4'-diamine (NPD), N-isopropylcarbazole, pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadiazole derivatives and phthalocyanine derivatives Compounds and the like, and, in a polymer system, a polycarbonate or a styrene derivative having the low-molecular compound in a side chain, polyvinyl carbazole,
Preferred examples include polysilane.

In the application of the simple matrix type light emitting device, the light emitting time of each organic electroluminescent element is short, and it is necessary to instantaneously emit light with high luminance by passing a pulse current. In such a case, the hole transporting material has not only excellent hole transporting properties and stable thin film forming ability, but also good electron blocking properties to prevent a decrease in luminous efficiency due to leakage of electrons in the hole transporting layer. Required. In order to satisfy the above characteristics in a well-balanced manner, in the present invention, it is particularly preferable to form a hole transport layer made of an organic compound having a biscarbazolyl skeleton shown below.

[0029]

Embedded image Here, R1 and R2 are selected from hydrogen, alkyl, halogen, aryl, aralkyl and cycloalkyl. The carbazolyl skeleton may have one or more substituents selected from alkyl, aryl, aralkyl, carbazolyl, substituted carbazolyl, halogen, alkoxy, dialkylamino, and trialkylsilyl groups.

Examples of the light emitting material include anthracene derivatives, pyrene derivatives, 8-hydroxyquinoline aluminum derivatives, bisstyrylanthracene derivatives, tetraphenylbutadiene derivatives, coumarin derivatives, and oxadiazole, which have been known as light emitters in the case of low molecular weight compounds. Derivatives, distyrylbenzene derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, thiadiazolopyridine derivatives, etc., in the case of polymer systems, polyphenylenevinylene derivatives,
Preferred examples include polyparaphenylene derivatives and polythiophene derivatives. Preferred examples of the dopant for doping the light-emitting layer include rubrene, quinacridone derivatives, phenoxazone derivatives, DCM, perinone derivatives, perylene derivatives, coumarin derivatives, and diazaindacene derivatives.

Since the electron transporting material is required to efficiently transport the electrons injected from the cathode, it is preferable that the electron transporting material has a large electron affinity, a large electron mobility, and a stable thin film forming ability. As materials satisfying such characteristics, 8-hydroxyquinoline aluminum derivatives, hydroxybenzoquinoline beryllium derivatives, 2- (4-
Biphenyl) -5- (4-t-butylphenyl) -1,
3,4-oxadiazole (t-BuPBD), 1,3
-Bis (4-t-butylphenyl-1,3,4-oxadizolyl) biphenylene (OXD-1), 1,3-bis (4-t-butylphenyl-1,3,4-oxadizolyl) phenylene (OXD- Oxadiazole derivatives, triazole derivatives, phenanthroline derivatives and the like such as 7) can be mentioned as preferred examples.

The materials used for the above-described hole transporting layer, light emitting layer and electron transporting layer can be used alone to form each layer. As the polymer binder, polyvinyl chloride, polycarbonate, polystyrene, poly (N- Vinyl carbazole), polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polysulfone, polyamide,
Solvent-soluble resins such as ethyl cellulose, vinyl acetate, ABS resin, polyurethane resin, phenolic resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin,
It can be used by being dispersed in a curable resin such as a silicone resin.

In the simple matrix type color light emitting device described above, the light emitting layer is patterned, but the hole transport layer and the electron transport layer are not necessarily patterned. That is, they may be formed on the entire surface of the substrate on which the first electrodes and the projections are formed. Further, in the case of a monochrome light emitting element, the light emitting layer can be formed over the entire surface of the substrate. The method of forming the hole transporting layer, the light emitting layer, and the electron transporting layer is not particularly limited, such as a resistance heating method, an electron beam method, and a sputtering method, but the former method is usually preferable in terms of characteristics. The thickness of the organic layer cannot be limited because it is related to its resistance value, but is selected from the range of 10 to 1000 nm.

It is also possible to use an inorganic material for the whole or a part of the hole transport layer or the electron transport layer. Preferred materials include silicon carbide-based, gallium nitride-based, zinc selenide-based, and zinc sulfide-based inorganic semiconductor materials.

In the present invention, the second electrode is formed after the formation of the thin film layer. When ITO is used as the first electrode, the second electrode functions as a cathode. The second electrode material is not particularly limited as long as it can efficiently inject electrons into the organic electroluminescent device. Therefore, it is possible to use a low work function metal such as an alkali metal, but considering the stability of the electrode, a metal such as platinum, gold, silver, copper, iron, tin, aluminum, magnesium, indium, titanium, nickel, etc. Or an alloy of these metals with a low work function metal is a preferred example. Further, from the viewpoint of improving the contrast and the like, it is preferable that at least a portion of the second electrode that is in contact with the thin film layer is black. Preferable examples of the black material include chromium, carbon, and high carrier density inorganic semiconductor materials obtained by impurity doping.

For the second electrode, a thin film layer is doped with a small amount of a low work function metal in advance, or a thin layer of a metal salt such as lithium fluoride is formed on the thin film layer in advance, and then a relatively stable layer is formed. By forming a suitable metal as the second electrode, a stable electrode can be obtained while keeping the electron injection efficiency high. The method for forming these electrodes is preferably a vapor deposition method such as a resistance heating method or an electron beam method, or a dry process such as a sputtering method or an ion plating method.

The method of patterning the second electrode is not limited, and includes a partitioning method disclosed in JP-A-5-275172 and JP-A-8-315981, a mask evaporation method, a laser ablation method, and the like. However, a mask vapor deposition method that can cope with a wide range of electrode forming conditions is preferable.

When the first electrode is patterned into a plurality of stripe-shaped electrodes arranged at a predetermined interval, the second electrode also has a plurality of intersecting (often orthogonal) stripes. The matrix of the light emitting region is formed by patterning the electrode. However, in the shadow mask corresponding to such a second electrode pattern, there is a problem that the mask portion becomes thin like a thread and the shape of the opening is deformed due to bending or the like.

FIGS. 8 and 9 show a preferred structure of the organic electroluminescent device of the present invention which solves this problem. The plurality of second electrodes 8 are electrically connected to the guide electrodes 4 to electrically
Function as two striped electrodes. The shadow mask for patterning these second electrodes is shown in FIG.
0. Since the reinforcing line 33 can be introduced across the opening to prevent the deformation of the stripe-shaped opening 32, the strength of the shadow mask is dramatically improved, and the effect of achieving fine patterning is as follows. it is obvious.

Another example of a shadow mask preferably used in the present invention is shown in FIGS. This shadow mask has an opening 3 having a shape corresponding to the second electrode pattern.
2 are provided, and there is a reinforcing line 33 formed across the opening to prevent deformation of the opening. Further, the shadow mask is fixed to a frame 34 for easy handling. By vapor deposition with the surface 35 of the shadow mask on which the reinforcing line does not exist in close contact with the substrate, the second electrode material that has flown from the reinforcing line 33 side has the gap
The second electrode is patterned into the shape of the opening 32 without being separated by the reinforcing line.

In the above two examples, patterning is performed in one deposition step. However, by using a plurality of shadow masks, or by relatively shifting the position of one shadow mask and the substrate, It can be divided into a plurality of vapor deposition steps. Alternatively, the shadow mask may be formed of a magnetic material, and a magnet may be disposed on the back side of the substrate to improve the adhesion between the two.

In the patterning step by the mask vapor deposition method as described above, the shadow mask comes into contact with the projections formed on the substrate, so that the organic layer or the like previously formed in the light emitting region is not damaged. That is, the presence of the protrusion in the present invention also has the effect of preventing mask flaws.

One of the features of the present invention resides in that the second electrode is electrically connected to a guide electrode existing outside the second electrode via the protrusion. In the present invention, as shown in FIG. 13, it is preferable to form a conductive portion 11 on the surface of the insulating protrusion 3 and electrically connect the two via this. As a method for forming the conductive portion, the conductive portion is formed simultaneously in the step of forming the second electrode, that is, the second electrode also serves as the conductive portion as already exemplified in FIG. 2 or FIG. Is preferred. By doing so, both the layers are not affected by an organic material thin film such as a hole transport layer that adheres to the surface of the projection in the step before the formation of the second electrode (they are omitted in the drawing). Can be connected.

The method of electrically connecting the two via the projection is not particularly limited, but a method of bringing the conductive portion into close contact with the guide electrode is preferable. Since at least a part of the projection is formed so as to exceed the thickness of the thin film layer, the two can be easily brought into close contact with each other as shown in FIG. 13, but, for example, as shown in FIG. It is also possible to further improve the adhesion between the two by inserting a projection into this portion. Further, a reinforcing means 12 may be formed on the conductive portion 11 as shown in FIG. 15 for the purpose of reinforcing the connection portion or improving the adhesion between them. The reinforcing means is not particularly limited as long as it is a conductive substance, but is preferably formed using a material having a relatively low hardness in order to improve adhesion.

Further, as shown in FIG.
1 and the guide electrode 4 can also be bonded by the fixing means 13. Examples of the fixing method include a so-called soldering method using a low melting point metal alloy such as indium or tin, gold,
Uses an anisotropic conductive film formed by dispersing conductive fine particles in a binder, using a conductive coating agent containing a powder of silver, copper, nickel, carbon, graphite, etc., or a conductive adhesive. And the like.

The structure of the guide electrode is not particularly limited. A conductive wire such as a lead wire or a conductive sheet such as aluminum foil can be used as it is, but in the present invention, a guide electrode is formed on a substrate different from the substrate on which the organic electroluminescent element is formed. Is preferred. By doing so, not only the handling of the guide electrode,
It becomes easy to pattern the guide electrode into a desired shape in advance.

In the simple matrix type light emitting device shown as a preferred example in the present invention, as shown in FIG. 1, the second electrode 8 may be patterned into a plurality of stripe-shaped electrodes arranged at predetermined intervals. Regardless of whether the second electrode 8 is patterned into a plurality of independent electrodes as shown in FIG. 8, the guide electrodes are preferably a plurality of stripe-shaped electrodes arranged at a predetermined interval. By doing so, each light emitting region is electrically connected to the driving source through the guide electrode whose resistance is sufficiently reduced, and the effect of the present invention becomes clear. The guide electrode preferably has a resistance of 2 kΩ / m or less as a guide, more preferably 500 Ω / m or less. Basically, the lower the resistance, the better. However, an optimum value may be selected according to the structure and size of the light emitting element, the duty ratio, the luminous efficiency, the conditions for forming the guide electrode, and the like.

The shape and size of the guide electrode may be optimized as needed. In order to facilitate connection with the second electrode, conductive projections may be provided on the guide electrode, or irregularities may be formed on the electrode surface. It is advantageous from the viewpoint of resistance value to form the guide electrode thick, but it is difficult to form the guide electrode. The method for patterning the guide electrode is not particularly limited. In addition to the usual photolithography method using etching or lift-off, a photosensitive paste method in which a photosensitive conductive paste is directly exposed and developed and then fired, a screen printing method, a sand blast method, a mold method, a mechanical polishing or excavation method , A laser processing method, an electroforming method, a fine particle aggregation method of directly drawing and aggregating conductive ultrafine particles on a substrate, or the like can be used.

As the substrate, not only the above-exemplified transparent substrate material but also any known material can be used. However, an insulating material is preferable because a guide electrode is patterned thereon. The transparency of the substrate is not so important, but rather, it is preferable that the substrate has a light absorbing property from the viewpoint of improving the display contrast. The form is not limited to a plate shape or a film shape. Alternatively, the guide electrode can be transferred by temporarily forming a guide electrode on the substrate, electrically connecting the guide electrode to the second electrode via the protrusion, and then removing the substrate. In such a case, it is preferable to use a film-like substrate.

In the present invention, in order to prevent deterioration of the light emitting characteristics due to moisture or oxygen, it is preferable to perform sealing by bonding a substrate on which an organic electroluminescent element is formed and a substrate on which a guide electrode is formed. Figure 1 shows the preferred structure.
It is shown in FIG. The light emitting region is sealed by the two substrates 1a and 1b and the sealing means 14, and the substrate 1b on which the guide electrode is formed also functions as a sealing plate. In many cases, the interior is filled with an inert liquid or an inert gas from which water has been sufficiently removed. By making the internal pressure lower than the atmospheric pressure, it is possible to improve the adhesion between the second electrode and the guide electrode by applying a suction force between the two substrates.

Examples of the inert liquid include silicone oil, grease, and fluorocarbon oil.
Examples of the inert gas include rare gases such as helium and argon, nitrogen, and carbon dioxide. These gases may contain a relatively small amount of relatively active gas such as oxygen. In order to obtain a sufficient sealing effect, the dew point of the gas is preferably −60 ° C. or lower, more preferably −100 ° C. or lower.

In addition, a moisture absorbent such as silica gel, zeolite, activated carbon, calcium oxide, germanium oxide, barium oxide, magnesium oxide, phosphorus pentoxide, calcium chloride, or the like can be provided inside the sealing region,
A getter film of magnesium, barium, titanium, or the like can also be formed.

It is preferable to use a curable resin as the sealing means. Examples of the resin material include known materials such as an epoxy-based, silicone-based, acrylic-based, and urethane-based material, and examples of the curing method include an ultraviolet irradiation method, a thermosetting method, and a curing agent mixing method. In the illustrated structure of FIG. 17, the guide electrode 4 is used as a lead electrode of the second electrode 8 as it is, but a lead electrode is formed on a substrate on which an organic electroluminescent element is formed, or a through hole is provided to provide a back side of the substrate. The electrode can be pulled out from.

A protective layer may be formed on the second electrode irrespective of the presence or absence of the above sealing. As the protective layer, in addition to the first electrode and second electrode materials already exemplified, inorganic materials such as silicon oxide, gallium oxide, titanium oxide, and silicon nitride, various polymer materials, and organic materials constituting an organic electroluminescent element are used. Can be used. Among them, silicon nitride is a suitable protective layer material having excellent moisture barrier properties. These protective films are formed by vapor deposition, sputtering, CVD
Although it is formed by a method, in the case of a conductive material, in order to prevent an undesired short circuit between the second electrodes, in the case of an insulating material, the conductive portion formed on the surface of the protrusion is not completely covered. In addition, it is preferable to pattern the protective layer by a method already exemplified, such as a mask evaporation method.

[0055]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 For patterning a light emitting layer, a stripe-shaped opening as shown in FIG. 18 was provided, and a reinforcing line was formed so as to cross the opening. The mask portion and the reinforcing line were in the same plane. A shadow mask having the formed structure was prepared. The external shape of this shadow mask is 120 × 84 mm, and the thickness of the mask portion is 25 μm. 272 stripe-shaped openings 32 having a length of 64 mm and a width of 100 μm are arranged at a pitch of 300 μm. In each of the stripe-shaped openings, a reinforcing wire 33 having a width of 20 μm and crossing the openings at right angles is 1.8 mm in pitch.
It is formed with. Further, the shadow mask is fixed to a stainless steel frame 34 having the same outer shape and a width of 4 mm.

For patterning the second electrode, one surface 35 of the mask portion 31 as shown in FIGS.
A shadow mask having a structure in which a gap 36 is present between the shadow mask and the reinforcing wire 33 was prepared. The outline of the shadow mask is 120 ×
84 mm, the thickness of the mask portion is 100 μm, and 200 stripe-shaped openings 32 having a length of 100 mm and a width of 250 μm are arranged at a pitch of 300 μm. On the mask portion, a mesh-like reinforcing line having a regular hexagonal structure having a width of 40 μm, a thickness of 35 μm, and a distance between two opposing sides of 200 μm is formed. The height of the gap 36 is equal to the thickness of the mask portion and is 100 μm. The shadow mask is fixed to a stainless steel frame 34 having the same outer shape and a width of 4 mm.

The patterning of the first electrode was performed as follows. An ITO substrate (manufactured by Geomatic) having a 150 nm-thick ITO transparent electrode formed on a 1.1 mm-thick non-alkali glass substrate surface by sputtering deposition
It was cut into a size of 20 × 100 mm. A photoresist was applied on the ITO substrate, and the photoresist was patterned by exposure and development with a photomask by a normal photolithography method. After removing unnecessary portions of the ITO by etching, the photoresist was dissolved and removed, and the ITO was patterned into a stripe shape having a length of 90 mm and a width of 80 μm. The 816 first electrodes patterned in a stripe pattern are arranged at a pitch of 100 μm.

The first electrode having the patterned first electrode formed thereon
Projections were formed on the TO substrate as follows. Polyimide photosensitive coating agent (UR-31, manufactured by Toray Industries, Inc.)
00) on the ITO substrate by a spin coating method, and then at 80 ° C. in a clean oven under a nitrogen atmosphere.
Prebaked for hours. Next, a desired portion is light-cured by pattern exposure of the coating film through a photomask,
It developed using the developing solution (Toray Co., DV-505).
Thereafter, baking was performed in a clean oven at 180 ° C. for 30 minutes, and further at 250 ° C. for 30 minutes, and FIG.
As shown in FIG.
Was formed. This projection has a length of 80 mm, a width of 30 μm,
It has a height of about 5 μm and is arranged so as to cover the edge of the first electrode at a pitch of 100 μm. Note that the projections had good electrical insulation.

The ITO substrate on which the projections were formed was washed, subjected to UV-ozone treatment, and then set in a vacuum evaporation machine. Further, the shadow mask for the light emitting layer and the shadow mask for the second electrode were set in a vacuum evaporation machine. In this vacuum vapor deposition machine, it is possible to position the substrate and the shadow mask in a vacuum with an accuracy of about 10 μm each.

The thin film layer was formed as follows by a vacuum evaporation method using a resistance wire heating method. The degree of vacuum at the time of vapor deposition was 2 × 10 ⁻⁴ Pa or less, and the substrate was rotated with respect to the vapor deposition source during vapor deposition.

First, copper phthalocyanine was added to 20 nm
(N-ethylcarbazole) was deposited on the entire surface of the substrate to a thickness of 120 nm to form a hole transport layer.

Next, as shown in FIG. 19, a shadow mask for a light emitting layer is disposed in front of the substrate so that both are brought into close contact with each other, and a ferrite plate magnet 37 (YBM, manufactured by Hitachi Metals, Ltd.) is provided behind the substrate.
-1B). At this time, the striped first electrode 2
Are positioned at the center of the stripe-shaped opening 32 of the shadow mask. Further, since the mask portion 31 comes into contact with the projection 3, the hole transport layer 5 formed earlier is not damaged. In this state, 4,4'-
Bis (2,2'-diphenylvinyl) biphenyl (DP
VBi) was deposited to a thickness of 30 nm, and the B light emitting layer 6 was patterned. Similarly, an 8-hydroxyquinoline aluminum complex (Alq ₃ ) was deposited to a thickness of 30 nm to form a G light emitting layer of 1 wt.
% Of 4- (dicyanomethylene) -2-methyl-6- (p
- dimethylamino styryl) -4-pyran (Alq ₃ doped with DCM) to 30nm deposited and patterned R emission layer, respectively.

Further, DPVBi was set to 70 nm, Alq ₃
Was deposited on the entire surface of a 30 nm substrate to form an electron transport layer.
Thereafter, the thin film layer was exposed to lithium vapor for doping (0.5 nm in terms of film thickness).

The second electrode was formed as follows by a vacuum evaporation method using a resistance wire heating method. The degree of vacuum at the time of vapor deposition was 2 × 10 ⁻⁴ Pa or less, and the substrate was rotated with respect to two vapor deposition sources during vapor deposition. In the same manner as in the patterning of the light emitting layer, a shadow mask for the second electrode was arranged in front of the substrate so that they were in close contact with each other, and a plate magnet was arranged behind the substrate. In this state, aluminum was evaporated to a thickness of 200 nm to pattern the second electrode. The second electrode was formed in a stripe shape so as to cover the surface of the protrusion without being separated by the reinforcing line of the shadow mask.

The guide electrode was formed as follows. 130 × 90m soda lime glass substrate with 1.1mm thickness
m. Next, a photosensitive silver paste containing silver powder as a main component was applied to the entire surface of the substrate, exposed and developed through a photomask, and then baked to pattern a striped silver electrode having a thickness of about 10 μm. .
This electrode has a length of 120 mm, a width of 200 μm, and 3
200 pieces are arranged at a pitch of 00 μm. The electrical resistance in the longitudinal direction was about 15Ω / m.

Next, the substrate on which the organic electroluminescent element was formed and the substrate on which the guide electrode was formed were opposed to each other, and the second electrode and the guide electrode were positioned so as to overlap with each other. Fixed in state.

As described above, as schematically shown in FIGS. 1 to 3, the thin film layer 10 including the patterned RGB light emitting layer 6 is formed on the striped first electrode 2, and the first electrode 250μm width, 300 pitch so as to be orthogonal
A simple matrix type color light emitting device in which a second electrode 8 having a stripe shape of μm was formed and the second electrode was electrically connected to the guide electrode 4 via the protrusion 3 was produced. Since the three light emitting regions of RGB form one pixel, the present light emitting element has 272 × 200 pixels at a pitch of 300 μm.

The light emitting area has a size of 70 × 250 μm and R
Light was emitted uniformly in independent colors of GB. When the present light emitting element was driven line-sequentially with the first electrode as a data line and the second electrode as a scanning line, clear pattern display and multi-color display were possible. In particular, since the resistance of the second electrode (scanning line) where the current is concentrated was sufficiently reduced by the addition of the guide electrode, the in-plane luminance unevenness was suppressed to 20% or less even when all the pixels emitted light.

Comparative Example 1 A simple matrix type color light emitting device was produced in the same manner as in Example 1 except that no guide electrode was added. The light emitting area was 70 × 250 μm in size, and emitted light uniformly in RGB independent colors. However, since the resistance of the second electrode (scanning line) was not reduced, the in-plane luminance when all pixels emitted light. The unevenness increased to 100% or more.

Comparative Example 2 A simple matrix type color light emitting device was produced in the same manner as in Example 1 except that no projection was formed. However, the first electrode and the second electrode were short-circuited due to the influence of the mask flaw and the contact flaw of the guide electrode, so that many pixels did not emit light.

Example 2 For patterning the second electrode, there is a stripe-shaped opening as shown in FIG. 10 and there is a reinforcing line formed so as to cross it, and the mask portion and the reinforcing line are in the same plane. A shadow mask having the structure formed in was formed. The external shape of this shadow mask is 120 × 84 mm, and the thickness of the mask portion is 25 μm. 200 stripe-shaped openings 32 having a length of 100 mm and a width of 250 μm are arranged at a pitch of 300 μm. In each of the stripe-shaped openings, a reinforcing wire 33 having a width of 20 μm and crossing the openings at right angles is provided at a pitch of 1.8.
mm. Further, the shadow mask is fixed to a stainless steel frame 34 having the same outer shape and a width of 4 mm.

A simple matrix type color light emitting device was produced in the same manner as in Example 1 except that the second electrode was patterned according to Example 1 using this shadow mask. This light emitting device is schematically shown in FIGS.
RGB patterned on the striped first electrode 2
A thin film layer 10 including a light emitting layer 6 is formed, and a second electrode 8 having a length of 1.8 mm and a width of 250 μm is arranged on the thin film layer in a grid pattern.
It is electrically connected to. Therefore, the plurality of second electrodes electrically function as one striped electrode.

This light-emitting element showed a clear pattern display similarly to that obtained in Example 1, and the in-plane luminance unevenness was suppressed. That is, it was confirmed that the second electrode patterned in a lattice shape functions as a stripe-shaped electrode by adding a guide electrode.

Example 3 After forming an organic electroluminescent device and a guide electrode respectively in the same manner as in Example 1, a commercially available two-part epoxy resin adhesive (manufactured by Ciba Geigy) under an argon atmosphere having a dew point of -100 ° C. or less. , Araldite).

As described above, a simple matrix type color light emitting device having a structure similar to that of Example 1 was manufactured. Further, as shown in FIG. 17, the present light emitting element is sealed by a sealing means (epoxy resin) 14, and the inside is filled with an argon gas containing almost no moisture.

This light emitting device showed a clear pattern display similar to that obtained in Example 1. Furthermore, even if the present light emitting device is left in the air for one month, a dark spot (D
The presence of a non-light emitting region called S) could not be confirmed with the naked eye. In the case where sealing is not performed, DS can be recognized only by leaving for one day, and thus the storage stability of the present light emitting device is greatly improved by using the substrate on which the guide electrode is formed as a sealing plate. .

Example 4 A simple matrix type color light emitting device was produced in the same manner as in Example 1 except that the projections were formed as follows.

40% methacrylic acid, 30% methyl methacrylate, and 30% styrene are copolymerized, and 0.4 equivalent of glycidyl methacrylate is added to the side chain carboxyl group of the copolymer to cause an addition reaction. Acrylic copolymer having a group and an ethylenically unsaturated group was obtained. 50 parts by weight of this acrylic copolymer, 20 parts by weight of a bifunctional urethane acrylate oligomer (UX-4101, manufactured by Nippon Kayaku Co., Ltd.) as a photoreactive compound, and hydroxypivalate ester neopentyl glycol diacrylate (Nippon Kayaku Co., Ltd.) HX-220) 20
200 parts by weight of cyclohexane was added to parts by weight, and the mixture was stirred at room temperature for 1 hour to obtain a resin component solution. To this resin component solution, 8 parts by weight of diethylthioxanthone (DETX-S, manufactured by Nippon Kayaku Co., Ltd.) as a photopolymerization initiator and p-
3 parts by weight of dimethylaminobenzoic acid ethyl ester (manufactured by Nippon Kayaku Co., Ltd., EPA) were added, and as a coloring agent, a 30% by weight solution of an azo chromium complex salt oil-soluble dye methyl ethyl ketone / methyl isobutyl ketone (3804T manufactured by Orient Chemical Co., Ltd.) ) And a phthalocyanine-based black pigment were added and stirred at room temperature for 20 minutes to obtain a photosensitive black paste.

After adjusting the concentration of the photosensitive black paste, the photosensitive black paste was applied on a patterned ITO substrate by spin coating, and prebaked in a clean oven at 80 ° C. for 5 minutes in a nitrogen atmosphere. The coating film is irradiated with ultraviolet light through a photomask to be light-cured,
% 2-aminoethanol aqueous solution. afterwards,
Baking was performed at 120 ° C. for 30 minutes in a clean oven to form black protrusions. As shown in FIG. 4, the black projections are formed in a matrix so as to expose the first electrodes 2 in a grid pattern, and have a width of 30 μm and a height of about 5 μm.
It is.

This light emitting device showed a clear pattern display similar to that obtained in Example 1. Further, since a black protrusion is formed around the light emitting region and functions as a black matrix, the display contrast is improved as compared with the first embodiment.

[0082]

The organic electroluminescent device of the present invention and the method of manufacturing the same have the following effects.

(1) The resistance of the second electrode is reduced by the addition of the guide electrode, so that the power consumption of the light emitting element and the load on the drive circuit are reduced. In a light-emitting element in which a plurality of pixels exist in a plane as in a simple matrix type display, luminance unevenness can be greatly reduced, and a reduction in heat generation and an improvement in durability due to an increase in heat radiation efficiency can be expected. This effect increases as the size of the display increases.

(2) Since the second electrode and the guide electrode are connected via the projection formed higher than the thin film layer, poor contact between them is less likely to occur, and the guide electrode may damage the light emitting region. Is prevented. Further, when patterning is performed by the mask evaporation method, introduction of a mask flaw is also prevented. Therefore, the production efficiency of the light emitting device is improved.

(3) Since a plurality of second electrodes can be made to function electrically as one electrode by adding a guide electrode, the second electrodes can be patterned using a shadow mask having high strength. Therefore, the flatness, handling, and adhesion of the shadow mask are improved,
The durability of the shadow mask is improved, and the production efficiency of the light emitting device is improved.

(4) Since the sealing can be performed by a relatively simple process using the substrate on which the guide electrode is formed, the storage stability and durability of the light emitting element are improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the organic electroluminescent device of the present invention (only the light emitting device side is shown).

FIG. 2 is a sectional view taken along the line XX ′ of FIG. 1;

FIG. 3 is a sectional view taken along line YY ′ of FIG. 1;

FIG. 4 is a plan view showing an example of a projection.

FIG. 5 is a plan view showing an example of a projection.

FIG. 6 is an XX ′ cross-sectional view showing an example of a projection.

FIG. 7 is an XX ′ cross-sectional view showing an example of a projection.

FIG. 8 is a plan view showing an example of the organic electroluminescent device of the present invention (only the light emitting device side is shown).

FIG. 9 is a sectional view taken along the line XX ′ of FIG. 8;

FIG. 10 is a plan view showing an example of a shadow mask for patterning a second electrode.

FIG. 11 is a plan view showing an example of a shadow mask for patterning a second electrode.

FIG. 12 is a sectional view taken along the line XX ′ of FIG. 11;

FIG. 13 is an enlarged cross-sectional view along XX 'showing an example of a method of electrically connecting a second electrode to a guide electrode.

FIG. 14 is an enlarged cross-sectional view along XX ′ showing an example of a method of electrically connecting a second electrode to a guide electrode.

FIG. 15 is an enlarged cross-sectional view along XX ′ showing an example of a method of electrically connecting a second electrode to a guide electrode.

FIG. 16 is an enlarged cross-sectional view along XX ′ showing an example of a method of electrically connecting a second electrode to a guide electrode.

FIG. 17 is a sectional view taken along line XX ′ showing an example of a sealing method.

FIG. 18 is a plan view showing an example of a shadow mask for patterning a light emitting layer.

FIG. 19 illustrates an example of a light emitting layer patterning method.
X 'sectional view.

FIG. 20 is a cross-sectional view illustrating an example of a conventional organic electroluminescent element.

FIG. 21 is a plan view showing an example of a conventional organic electroluminescent element.

FIG. 22 is a sectional view taken along the line XX ′ of FIG. 21;

FIG. 23 is a sectional view taken along line YY ′ of FIG. 21;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Substrate on which organic electroluminescent element is formed 1b Substrate on which guide electrode is formed 2 First electrode 3 Projection 4 Guide electrode 5 Hole transport layer 6 Light emitting layer 7 Electron transport layer 8 Second electrode 9 Drive source 10 Thin film Layer 11 Conductive part 12 Reinforcement means 13 Adhesion means 14 Sealing means 31 Mask part 32 Opening 33 Reinforcement line 34 Frame 35 One surface of mask part 36 Gap 37 Magnet

Continued on the front page F term (reference) 3K007 AB00 AB02 AB03 AB11 AB15 AB18 BA06 CA01 CA05 CB01 DA00 DB03 EB00 FA01 5C094 AA03 AA22 AA25 BA12 BA29 CA19 CA24 DA13 EA05 FA02 FA04 FB12 5C096 AA05 BA04 BC20 CA03 CC07 CC23

Claims (12)

[Claims] A first electrode formed on a substrate, a thin film layer including at least a light emitting layer made of an organic compound, formed on the first electrode, and a second electrode formed on the thin film layer. Is present, an organic electroluminescent device having a plurality of light emitting regions on the substrate, wherein at least a portion having a height greater than the thickness of the thin film layer is formed on the substrate, via the protrusion Wherein the second electrode is electrically connected to a guide electrode existing outside the second electrode. 2. The method according to claim 1, wherein the first electrode is a plurality of striped electrodes arranged on the substrate at intervals, and at least one of the second electrode and the guide electrode is a plurality of striped electrodes intersecting the first electrode. The organic electroluminescent device according to claim 1, wherein the device is an electrode. 3. The organic electroluminescent device according to claim 1, wherein a plurality of second electrodes are electrically connected to the guide electrode to function as one second electrode. 4. The organic electroluminescent device according to claim 1, wherein the second electrode is electrically connected to the guide electrode via a conductive portion formed on the surface of the insulating projection. 5. The organic electroluminescent device according to claim 1, wherein at least a part of the projection is black. 6. The projection according to claim 2, wherein the projections are formed in a matrix so as to expose the first electrodes in a grid.
The organic electroluminescent device according to claim 1. 7. The organic electroluminescent device according to claim 1, wherein a guide electrode is formed on a substrate different from the substrate on which the organic electroluminescent device is formed. 8. The organic electroluminescent device according to claim 7, wherein the substrate on which the organic electroluminescent device is formed and the substrate on which the guide electrode is formed are laminated to seal the organic electroluminescent device. Electroluminescent device. 9. The electric resistance in the longitudinal direction of the guide electrode is 2 kΩ.
The organic electroluminescent device according to claim 2, wherein the ratio is not more than / m. 10. A method for manufacturing an organic electroluminescent device according to claim 1, wherein a step of patterning a first electrode formed on the substrate, and a step of forming a projection on the substrate.
A step of forming a thin film layer, and a step of forming a second electrode,
Electrically connecting the second electrode to a guide electrode existing outside the second electrode via the protrusion. 11. The method according to claim 10, wherein in the step of forming the second electrode, a conductive portion electrically connected to the second electrode is formed on the surface of the projection. Method. 12. The method according to claim 10, wherein the second electrode is patterned by a mask deposition method.