JPH1140370A - Organic el display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain uneven brightness and heat generation and make a display possible with a large area by connecting a cathode or an anode to an electrode pattern formed on its outside. SOLUTION: In a typical panel structure, a red luminescent layer 30 is formed on an anode 32 formed into a stripe on a glass substrate 31, and a cathode 29 having approximately equal width as the luminescent layer 30 is produced so as to be orthogonal to an ITO transparent electrode. A back surface substrate 28 is prepared, which is formed with a cathode 27 stripe-patterned in the same shape as a cathode 29 on the back surface substrate 28. The substrates prepared in the above way are affixed to each other so that the electrodes facing each other may conduct, by which a dot matrix panel which is capable of driving at low voltage without generating uneven brightness can be prepared. Sealing of an organic EL element so that it may be isolated from the open air would attain its purpose at the time of affixing work, and sealing for improving durability would be also attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display for converting electric energy into light and displaying the converted light, and more particularly to a self-luminous display which can be used for a bulletin board, a monitor, a flat display and the like.

[0002]

2. Description of the Related Art Recently, research has been actively conducted on organic thin-film light-emitting devices in which electrons injected from a cathode and holes injected from an anode emit light when they recombine in an organic phosphor sandwiched between both electrodes. It has become. This element is thin,
It features high-luminance light emission under low drive voltage and multicolor light emission by selecting a fluorescent material, and is attracting attention.

[0003] This study was carried out by Kodak Corporation. W. Tan
g. et al. showed that the organic laminated thin film element emits light with high luminance (Appl. Phys. Lett. 51 (12)
21, p. 913, 1987), and many research institutions are conducting studies. A typical configuration of an organic laminated thin film light emitting device presented by a research group of Kodak Company is a diamine compound having a hole transporting property and a light emitting layer on an ITO glass substrate.
Aluminum hydroxyquinoline and M as cathode
g: Ag was sequentially provided, and green light emission of 1000 cd / m ² was possible at a driving voltage of about 10 V. The present organic laminated thin-film light-emitting device has a different configuration, such as a device provided with an electron transport layer in addition to the above-described device components, but basically follows the configuration of Kodak Company.

A display using the present organic laminated thin-film light-emitting device can be expected to surpass a conventional display in that it can provide a thin, lightweight, and self-luminous display, but it is still unsolved for use as a display. There are many issues that need to be addressed. One of them is the enlargement of panels. Since the display emits light by injecting a current, if the current does not spread evenly to each pixel, luminance unevenness occurs on the screen. Further, if light emission is forcibly performed, a high voltage is required, so that driving becomes difficult or a problem of heat generation occurs. This is mainly because the specific resistance of ITO used as the anode is large, and it is difficult to flow a large current because the thickness cannot be increased because the cathode is manufactured by a vacuum deposition method. I have. In particular, when the screen size becomes large and the duty becomes high, the current flowing instantaneously becomes very large, so that the load on the display increases rapidly.

In order to increase the display area, it is necessary to lower the resistance of the electrodes. Specifically, a method of combining a transparent electrode such as ITO with a metal (Japanese Unexamined Patent Publication No.
253593, JP-A-5-307997)
It has been known.

[0006]

However, in the method of combining ITO and a metal, if the metal is overlaid on the entire surface of the transparent electrode, the metal absorbs light, so that the brightness is reduced. Since the aperture ratio of the panel is reduced, there is also a problem that the brightness is reduced in this case as well.

On the other hand, non-transparent electrodes (in many cases, cathodes) are usually formed by sequentially laminating an organic substance on a transparent electrode and then depositing the organic substance in the last step. The damage cannot be ignored,
Long time is required for vapor deposition. As described above, the organic EL device according to the present invention basically cannot produce a low-resistance electrode, so that when the panel is enlarged, luminance unevenness occurs remarkably, and a load is applied to the device and the electrode. Low,
Problems such as disconnection of the electrodes occur. .

[0008]

In order to achieve the above object, the present invention provides a display in which a substance which emits light exists between an anode and a cathode, and elements which emit light by electric energy are arranged in a matrix. The cathode or anode is connected to an electrode pattern formed outside the cathode or anode.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a negative electrode pattern having a low resistance value outside the anode or cathode of an organic EL element to supply a large current to a light emitting element at a low voltage, thereby reducing luminance unevenness and heat generation. This is for producing a display.

In the present invention, one of the anode and the cathode is a transparent electrode. Specific examples include conductive metal oxides such as tin oxide, indium oxide, and indium tin oxide (ITO); metals such as gold, silver, chromium, and osmium; and inorganic conductive substances such as copper iodide and copper sulfide; Although conductive polymers such as polythiophene, polypyrrole, and polyaniline are not particularly limited, it is particularly desirable to use ITO glass or Nesa glass from the viewpoint of high light transmittance and high electrical conductivity. The resistance of the transparent electrode is not limited as long as a sufficient current can be supplied for light emission of the element, but it is generally desirable that the resistance is low. For example, 3
An ITO substrate with a resistance of 00 Ω / □ or less functions as an element electrode, but a substrate with a resistance of about 10 Ω / □ can be supplied at present. Can be. However, since the ITO glass affects the organic EL device characteristics depending on its surface morphology and chemical composition, it is not always better to have a lower resistance, and it is important to select the ITO glass by balancing the device characteristics and the resistance value. . The thickness of the ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of usually 100 to 300 nm. When performing dot matrix display,
In order to suppress a short circuit at an edge portion of a pixel, it is preferable to use a thinner one.

Further, when the electrode connected to the electrode pattern formed outside in the present invention is a cathode, a guide electrode is provided on the transparent electrode as an anode to reduce the resistance value. A thin film layer having higher electric conductivity than the transparent electrode may be provided between the hole transport layers. In particular, the guide electrode
By inserting an insulating layer or leaving a gap so as not to short-circuit with an adjacent transparent electrode, it can also serve as a black matrix. As a material suitable for such a material, any form such as a powder or a thin film may be used, and an amorphous or graphite-based carbon material, a chromium material and the like are exemplified as suitable materials. However, in the case of a black matrix that does not serve as a guide electrode,
It is also possible to use the above substance after insulation treatment, or to use an organic compound such as a dye or a pigment. On the other hand, soda lime glass, non-alkali glass, or the like is used for the glass substrate for the transparent electrode, and the thickness is sufficient if the thickness is sufficient to maintain mechanical strength, so that 0.5 mm or more is sufficient. . As for the material of the glass, non-alkali glass is preferred because it is better that ions eluted from the glass are small, but soda lime glass having a barrier coat such as SiO ₂ is also commercially available, and can be used.
Substrates, sheets, films, and the like of polycarbonate, polymethyl methacrylate, polyethylene terephthalate, poly (4-methylpentene), polystyrene, ring-opening polymers of norbornene derivatives, cyclopentadiene polymers, and the like can also be used. The method of forming the ITO film is not particularly limited, such as an electron beam method, a sputtering method, an ion plating method, and a chemical reaction method.

The cathode is not particularly limited as long as it can efficiently inject electrons into the organic material layer.
Gold, silver, copper, iron, tin, aluminum, indium, lithium, sodium, potassium, calcium, magnesium, chromium, carbon, etc., and lithium, sodium for improving the electron injection efficiency and improving the device characteristics , Potassium, calcium, magnesium or alloys containing these low work function metals are effective. However, these low work function metals are generally unstable in the air in many cases. For example, an organic layer is doped with a very small amount of lithium or magnesium (1 nm or less as indicated by a film thickness gauge by vacuum evaporation) to form an electrode. As a preferable example, a method using a metal such as aluminum having high stability can be cited as a preferable example, but the method is not particularly limited thereto. The thickness of the cathode is selected from the range of 30 nm to 10 μm, but is not particularly limited. Factors that determine the film thickness are set so that the part that comes into contact with the electrode pattern formed on the outside has mechanical strength that can withstand the contact and electrical resistance that is not destroyed even when current flows. This should vary depending on the cathode material, the organic material, and the film thickness, so that an optimum film thickness should be selected at each time.

Further, in order to drive the element stably for a long time,
Platinum, gold, silver, copper,
Metals such as iron, tin, aluminum, indium, and chromium, or alloys using these metals, and inorganic materials such as silica, titania, silicon, and silicon nitride; and hydrocarbon-based materials such as polyvinyl alcohol, vinyl chloride, polyethylene, and polypropylene. Preferred examples include stacking molecules, fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, and materials known as shielding materials such as nylon, polyvinyl alcohol, and polyvinylidene chloride. And the formation method of these protective films is a solution coating method, a melt coating method, a vacuum evaporation method, a sputtering method, an electron beam evaporation method,
Any method that does not adversely affect device performance, such as a cluster ion beam method, a CVD method, an ionization vapor deposition method, a plasma polymerization method, and a vapor deposition polymerization method, can be used.
However, when an insulating material is used as the protective layer, an opening for connecting to the electrode pattern provided on the back surface is provided, or a material having high electric conductivity is provided only at the connection portion.

An element that emits light by electric energy is
It refers to an element in which a substance which emits light is included between the above-described anode and cathode. The present invention is preferably used for an organic electroluminescent device, but is not particularly limited to other light emitting devices such as an inorganic EL device made of an inorganic substance such as Zn: S as long as the concept of the present invention can be used.

The organic electroluminescent device usually comprises 1) a hole transport layer / a light emitting layer, 2) a hole transport layer / a light emitting layer / an electron transport layer,
3) The light-emitting layer / electron transport layer, and 4) any combination of the above-mentioned combined substances may be used. That is, as the element configuration, it is only necessary to provide a single layer containing a light emitting material, a hole transporting material and / or an electron transporting material as in 4) in addition to the above-described multilayered structures 1) to 3).
The hole transporting material is not particularly limited as long as it fulfills its function. Specifically, the porphyrin compound, Q
1-G-Q2 (Q1 and Q2 are independently a group having a nitrogen atom and at least three carbocycles, at least one of which is aromatic; G is a cycloalkylene group;
An arylene group, an alkylene group or a linking group comprising a carbon-carbon bond), N, N'-diphenyl-N, N '
-Bis (3-phenyl) -1,1'-biphenyl-4,
4'-diamine (TPD), N, N'-diphenyl-
N, N′-bis (1-naphthyl) -1,1′-biphenyl-4,4′-diamine (α-NPD), polyphosphazene derivative, polyvinylcarbazole (PVCz),
Polysilane, 4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine (m-MT
DATA), 4,4 ′, 4 ″ -tri (N-carbazolyl) triphenylamine (TCTA), bistriphenylamine styryl, triphenylamine oligomer, tetra or hexaamine derivatives, PTPDMA, hydrazone compounds, stilbene compounds Compounds, triphenylamine-based compounds, oxadiazole derivatives and phthalocyanines, metal phthalocyanines, heterocyclic compounds such as porphyrin compounds, bis (phenylcarbazole),
Bis (o-methylphenylcarbazole), bis (m-
Methylphenylcarbazole), bis (p-methylphenylcarbazole), bis (o-methoxyphenylcarbazole), bis (m-methoxyphenylcarbazole), bis (p-methoxyphenylcarbazole), bis (naphthylcarbazole), bis (methyl Naphthylcarbazole), bis (phenanthrolylcarbazole), bis (ethylcarbazole), bis (phenyliminodibenzyl), bis (m-methylphenyliminodibenzyl), tris (phenylcarbazole), tris (methylphenylcarbazole) , Tris (naphthylcarbazole), tris (methylnaphthylcarbazole), tris (phenanthrolylcarbazole), tris (ethylcarbazole), tris (phenyliminodibenzyl), tris (m-meth Le phenyl iminodiacetonitrile benzyl), a polymer system can be cited the polycarbonate and styrene derivatives having a monomer in the side chain, a polysilane derivative, and the like. These compounds can be used even if they are laminated or mixed.

[0016] Even if a single light emitting material is used,
A mixed light-emitting material obtained by a doping method (a method in which a dopant serving as a guest is mixed with a phosphor substance serving as a host to emit light from a dopant) may be used. Compounds that can be used as these host or guest molecules include tris (8-quinolinolato) aluminum, metal oxine derivatives such as tris (benzoquinolinolato) aluminum, 1,4-diphenylbutadiene, 1,1,4 , 4-Tetraphenylbutadiene, styryl compound, benzoxazole derivative, benzothiazole derivative, transstilbene, 7-dimethylamino-4-methylcoumarin, 3- (2'-benzimidazoyl) -7-N, N-diethylaminocoumarin Coumarin derivatives known to be useful as laser dyes, and dicyanomethylenepyran dyes typified by 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H pyran , Dicyano methylene thi Opiran dye, cyanine dye, xanthene dye, pyrylium dye, carbostyril dye, perylene,
Tetracene, pentacene, quinacridone compound, terphenyl, quarterphenyl, quinazoline compound, pyrrolopyridine, compound having a diazaindacene skeleton, furopyridine, 1,2,5-thiadiazolopyrene derivative,
Light-emitting materials such as perinone derivatives, pyrrolopyrrole compounds, squarylium compounds, and rare earth complexes can be used.

When doping, the doping amount is
Usually, concentration quenching occurs when the amount is too large, so that it is usually preferable to use 10% by weight or less based on the host substance.
More preferably, it is at most 2% by weight. As a doping method, a co-evaporation method with a host material can be used. There is a method of separately depositing in a deposition boat divided into two rooms, heating them at the same time, and then depositing. It is also possible to use a small amount of guest molecules sandwiched between host materials. The method for forming the light-emitting layer is not particularly limited, such as resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, and coating. However, resistance heating evaporation and electron beam evaporation are usually preferable in terms of characteristics. The thickness of the light-emitting layer cannot be limited because it depends on the resistance of the substance that controls light emission, but is empirically selected from the range of 10 to 1000 nm.

As the electron transport layer material, it is important to efficiently transport electrons from the cathode between the electrodes to which an electric field is applied, and it is desirable to have a high electron injection efficiency and to transport the injected electrons efficiently. . For this purpose, it is required that the material has a high electron affinity, a high electron mobility, a high stability, and a small amount of impurities serving as traps during production and use. Oxin-based complexes such as tris (8-quinolinolato) aluminum, tris (benzquinolinolato) aluminum, oxadiazole derivatives, triazine derivatives, and perylene derivatives, which are light-emitting substances having an electron-transporting ability, satisfying such conditions. , Perinone derivatives, naphthalene, coumarin, oxadiazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, pyridine derivatives, and phenanthroline derivatives. The electron transport layer material can take any form of single, laminated, or mixed, and can take an optimal form in combination with a light emitting layer and a cathode.

In the present invention, the light-emitting elements are basically arranged in a matrix. However, any display method that can utilize the concept of the present invention can be used in other arrangement methods. The matrix refers to a matrix in which pixels for display are arranged in a lattice, and displays a character or an image by a set of pixels. The shape and size of the pixel depend on the application. For example, a square pixel having a side of 300 μm or less is usually used for displaying images and characters on a personal computer, a monitor, and a television. In the case of a large display such as a display panel, a pixel having a side of mm order is used. . In the case of monochrome display, pixels of the same color may be arranged, but in the case of color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. However, the present invention can be used not only in a matrix but also in a segment system. In the segment type, a pattern is formed so as to display predetermined information, and a predetermined area emits light. For example, there are a time display and a temperature display on a digital clock or a thermometer, an operation state display of an audio device, an electromagnetic cooker, or the like, and a panel display of an automobile.
The matrix display and the segment display may coexist in the same panel.

Here, an example of the light emitting layer patterns arranged in a matrix is shown in FIGS. 1 to 8 (the cathode is not shown). FIG. 1 shows an example of monochromatic display of green, for example, in which each of the luminescent pixels is independently patterned. ITO, which is a transparent electrode formed in a stripe shape, is disposed on the glass substrate 1, and an organic material corresponding to a light emitting portion in a size of a display pixel is laminated thereon. Finally, the cathode may be formed in this pixel size or may be formed in a stripe shape perpendicular to the transparent electrode. However, it is important that the leakage current of each element in the display on the panel be as small as possible because it affects the crosstalk, the power consumption, and the durability of the element. For that purpose, it is necessary to eliminate the short circuit between the ITO transparent electrode and the negative electrode as much as possible.
It is also effective to pattern the organic material in a larger shape than the ITO electrode, cover the edge portion with the organic material, and suppress a short circuit with the cathode, or form the cathode slightly smaller so as not to cover the edge of the ITO. However, in the case of a monochrome display, an organic layered film may be formed without patterning the organic layer over the entire surface.

FIG. 2 shows an example of a color display.
6 to FIG. FIG. 2 to FIG. 4 show, on ITO, which is a transparent electrode formed in a stripe shape on a glass substrate, red 4, 9, or 12, green 5, 10, or 13, blue 6, 11, or 14 shows an example in which 14 light-emitting bodies are formed. These three differences are in the arrangement of the light emitters. FIG. 2 shows an arrangement in which light emitters of the same emission color are arranged on an ITO transparent substrate, FIG. 3 shows an arrangement of light emitters of the same emission color in a direction perpendicular to the ITO transparent electrode, and FIG. It is arranged. In the case of the arrangement shown in FIGS. 2 and 3, since the same color light-emitting bodies are arranged in the same direction, they can be connected continuously. An example is shown in FIG.
FIG. FIGS. 5 and 7 show organic light-emitting elements formed on the ITO electrode so that the same color extends over a plurality of pixels. FIGS. 6 and 7 show light-emitting elements formed of the same color in a direction perpendicular to the ITO electrode. FIG. In particular, in FIGS.
Even if slight misalignment occurs in the cathode fabrication,
Since the probability of short-circuiting between the anode ITO and the cathode is reduced as compared with the case where one pixel is formed, crosstalk and other problems are suppressed. However, in any case, it is possible to suppress the short circuit phenomenon by forming an organic thin film in a wider range than the ITO electrode, or to form a hole transport layer on the entire display portion and to use only one of the above luminescent materials. Forming in a pattern is also effective in suppressing the short circuit phenomenon.

The method of manufacturing the cathode of the device and the doping method performed before it are as described above. The form is the same as that of the luminous body. Any of the methods for suppressing the leak current between the electrodes can be used.
Conversely, when the edge portion of is covered with an insulator or an organic material, the negative electrode is formed to be larger than ITO, so that moisture and oxygen are prevented from entering from the side of the organic EL element, and the light emitting area is reduced. Can be suppressed. In addition, it is also possible to form a cathode so as to straddle each pixel without forming a negative electrode in a form corresponding to each of the above-mentioned independent light-emitting bodies. However, in this case, when a character or an image is displayed by the light emitting pixels of the dot matrix as shown in FIGS. 1 to 8, the negative electrode should be formed in a direction orthogonal to the ITO transparent electrode. Further, the second cathode may be formed so as to connect the cathodes formed corresponding to the respective pixels. This effect is obtained by making the width of the second cathode narrower than the pixel width, even if the width of the second cathode is smaller than the pixel width. That the resistance value of the cathode can be further reduced without short-circuiting with the pixel. Also, the second
The cathode can perform another function. It also has the effect of facilitating contact with the outer patterned electrodes. This is a problem of the smoothness of the substrate on which the organic EL is formed and the substrate on which the pattern electrode is formed, and there is no guarantee that any portions can be uniformly contacted. Therefore, by using the second electrode as a buffer layer, uniform contact can be made at any part. Therefore, when used as a buffer layer, the second cathode does not need to straddle each pixel, but is preferably a material which has a thickness enough to absorb the undulation of the substrate and is somewhat soft so that it can be contacted at different heights depending on the contact portion. It can be illustrated as an embodiment. However, when the adhesion between the electrode pattern formed on the outside and the light emitting layer is good, a method in which the electrode pattern is brought into close contact with the light emitting layer without preparing a cathode may be adopted.

In the present invention, the electrode pattern formed on the outside is usually formed on a substrate other than the substrate on which the organic EL element is formed (hereinafter referred to as a rear substrate). Therefore, the substrate in which the organic EL element is formed and the back substrate in which the electrode pattern is formed are finally attached while maintaining electrical continuity. The material of the back substrate is not particularly limited as long as an electrode pattern can be produced, but examples thereof include alumina, silicon nitride, a ceramic substrate such as silicon carbide, soda lime glass, a glass substrate such as non-alkali glass,
Metal substrates such as stainless steel, iron, aluminum, tin, chromium, nickel, and copper whose surfaces are insulated, bakelite, polyimide, polysulfone, polyethersulfone, ABS, polyethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, Selected from polymer substrates such as polytetrafluoroethylene, polyvinylidene chloride, polyethylene, polypropylene, liquid crystal polymer, polymethyl methacrylate or its copolymer, methyl acrylate or its copolymer, epoxy resin, maleimide resin, and aramid resin It is manufactured by singly, mixing, or laminating at least one kind of resin.

The back substrate according to the present invention can serve as a shielding plate for sealing the organic EL element in addition to the support for the electrode pattern. At this time, the substrate needs to have gas barrier properties. In particular, in the case of a polymer substrate, it is necessary to lower the gas permeability, so silica or titania, antimony oxide,
A gas barrier film of magnesium oxide, magnesium fluoride, tin oxide, indium oxide, indium tin oxide, etc. may be formed by a method such as coating, sol-gel method, vacuum deposition, etc., or glass and metal fine particles are mixed in a polymer. It is also possible to reduce the volume of the polymer portion to lower the gas permeability. As the fine particles at this time,
There is no particular limitation as long as it has an effect of lowering the gas permeability, such as alumina, silica, silicon nitride, silicon carbide, glass, metal, and carbon. The board thickness can maintain the shape,
There is no particular limitation as long as the display has gas barrier properties. However, when the display is required to be thin and lightweight, such as for portable use, it is preferable that the display can be made as thin as possible while maintaining the above characteristics. The back substrate may have a sheet or film shape satisfying the above conditions. It is often preferable that the smoothness of the back substrate is as smooth as possible, but it is particularly smooth if the portion electrically connecting the organic EL element substrate and the back substrate is high enough to absorb the undulation of the substrate. No need. However, it is often the case that the organic EL element substrate and the rear substrate are preferably smoothed by polishing or the like to give a good result. However, when polishing is performed, the number of steps increases, so that good connection should be made without polishing as much as possible.

In the present invention, the electrode pattern formed on the rear substrate is intended to be able to supply a sufficient current to a large-screen organic EL panel without large heat generation or voltage rise. The purpose is to suppress the migration phenomenon occurring at the metal electrode. Therefore, any conventionally known method can be used to achieve this purpose. For example, a method of patterning the metal part of a substrate bonded to a metal such as a bakelite or polyimide copper-clad substrate by photolithography, a method of printing a conductive paste by a method such as a screen printing method and, if necessary, a method of baking, and a method of also using a conductive paste. Can be exemplified by a method of patterning by a photolithography method, a method of patterning a photosensitive conductive paste by a photolithography method, and baking if necessary.However, if the desired pattern can be obtained and the above function can be exhibited, these methods are particularly limited. Not done. However, the resolution of the pattern increases in the order of the metal substrate etching method, the screen printing method, and the photosensitive paste method. Therefore, an effective method should be applied according to the shape and size of the pattern. The materials of the electrodes include gold (Au), silver (Ag), copper (Cu), palladium (P
d) a metal such as nickel (Ni), aluminum (Al), platinum (Pt), chromium (Cr), indium (In), lead (Pb), magnesium (Mg) or Ag
(30-80) -Pd (70-20), Ag (40-7)
0) -Pd (60-10) -Pt (5-20), Ag
(30-80) -Pd (60-10) -Cr (5-1
5), Pt (20-40) -Au (60-40) -Pd
(20), Au (75-80) -Pt (25-20),
Au (60-80) -Pd (40-20), Ag (40
~ 95) -Pt (60 ~ 5), Ag (80 ~ 98) -P
d (20-2), Ag (90-98) -Pd (10
2) -Pt (2-10), Ag (85-98) -Pt
Binary or ternary mixed metal powders such as (15-2) (where the parentheses indicate weight%), alloys containing the above metals,
Carbon, polypyrrole, polyaniline, polythiophene,
Any substance that can be patterned and has conductivity, such as polyacetylene, polyphenylenevinylene, and polysilane, can be used, or they can be mixed or laminated. From the viewpoint of driving at a low voltage without causing luminance unevenness, a material or a combination having a low specific resistance is preferable.However, even if the specific resistance is high, the resistance can be reduced by increasing the film thickness of the electrode. The form may be selected. On the other hand, in the electrode pattern of the present invention, the difference in the coefficient of thermal expansion between the substrate and the substrate becomes a problem, particularly in the case of baking. May not be obtained. In such a case, the problem may be solved by providing a buffer layer having a thermal expansion coefficient intermediate between the two materials.

The pattern shape is not generally shown because it depends on the driving method of the panel. However, basically, the pattern shape is such that it can contact at least one or more pixel electrodes of the elements formed on the organic EL substrate. There is a need. In the dot matrix panel as shown in FIGS. 1 to 8, the back electrode pattern is formed in a stripe shape in a direction orthogonal to the ITO transparent electrode. FIG. 9 shows a typical panel structure in the present invention. The luminescent pixels 30 are formed on the transparent electrodes 32 formed in stripes on the glass substrate 31 shown in FIG.
Is formed, and a negative electrode 29 having a width substantially equal to that of the light emitting pixel is manufactured so as to be orthogonal to the ITO transparent electrode. On the other hand, a back substrate is formed in which an electrode 27 patterned in a stripe shape in the same shape as the negative electrode is formed on the back substrate. By bonding the substrates manufactured in this manner so that the electrodes facing each other are conductive, a dot matrix panel that can be driven at low voltage without luminance unevenness is completed. Furthermore, if the organic EL element is sealed so as to be shielded from the outside air at the time of bonding, the above-mentioned purpose can be achieved and sealing for extending the durability can be performed at the same time.

At the time of sealing, silica gel, zeolite, carbon powder, activated carbon, calcium chloride,
Includes moisture-repellents such as activated alumina, anhydrous magnesium perchlorate, and barium oxide, and substances that react with moisture such as alkali metals and alkaline earth metals. It is effective in making Suitable examples of the sealing means include, but are not limited to, epoxy resin, cyanoacrylate resin, acrylic or epoxy photocurable resin, and the like.

The method of electrically connecting the negative electrode of the organic EL element to the electrode pattern formed on the rear substrate is not particularly defined, but is not limited to simply contacting the facing electrode pattern with the negative electrode of the organic EL element. Use of anisotropic conductive film as
A method of forming a conductive projection on one or both of the organic EL element and the back electrode and electrically connecting the same to each other may be used. One example is shown in FIGS. An organic EL element 35 is formed on a glass substrate 36. On the other hand, an electrode pattern 33 is formed on the rear substrate. If both substrates have high smoothness, it is possible to bond them as they are, but usually, it is preferable to provide conductive protrusions on one or both of the substrates as a buffer layer for establishing conduction between both electrodes. The cross-sectional shape is hemispherical (FIGS. 10, 11,
16), rectangular (FIGS. 12, 13, 17), trapezoidal (FIG. 1)
4, 15 and 17) and various shapes such as spherical, elliptical, polygonal and star-shaped are not particularly limited. However, these shapes may be deformed such that when the two substrates are bonded together, they are crushed within a range that does not cause a short circuit with another element. In addition, it is not necessary to arrange these protrusions in a form corresponding to all pixels, and it is possible to efficiently thin out the protrusions. Since the material of the projections must be electrically connected so as to fill the gap between the substrates within a certain range, a material that is relatively easily deformed by the bonding pressure is preferable. For example, gold, copper, aluminum, indium,
Examples include, but are not limited to, lead and magnesium. If the height of the projection is not higher than the maximum gap that can be formed between the substrates, the purpose cannot be achieved. Therefore, it is easy for both substrates to conduct as much as possible, or to have the same undulating shape. In order to increase the height, it is advantageous to form protrusions on both the cathode and the cathode pattern of the organic EL element. However, care must be taken because forming high protrusions on the element may cause deterioration in element performance. is necessary. As a method of forming the projection, vacuum deposition,
Any method such as screen printing and a method using a photosensitive conductive paste can be used, such as a method using a vacuum technique such as an electron beam method or a sputtering method. However, when the organic EL element is formed, the vacuum technique is used. This can suppress the deterioration of the device characteristics.

In consideration of the durability of the organic EL device, it is effective to provide a protective film on the outer peripheral portion of the device. FIG. 19 shows a conceptual diagram thereof. An insulating shielding film is formed on the outer periphery of the element to prevent moisture and oxygen from entering the inside of the element. However, if all parts are insulated, power cannot be supplied to the organic EL element. Therefore, the conductive projection 37 is formed to shield the element while maintaining conduction. As the material of the shielding layer, the above-described electrode protection material can be used as it is.

As another method, a method in which an electrode pattern is formed on a substrate in which a via hole is formed, and then the substrate is bonded to a substrate in which an organic EL element is formed can be used. 20 and 21 show schematic diagrams thereof. First, as shown in FIG. 20, an organic EL element (formed up to the negative electrode) 39 is formed on a glass substrate. On the other hand, a substrate (for example, made of alumina) 43 having a via hole 40 and a partition wall 41 formed around the via hole 40
An electrode pattern 42 is formed above and in the via hole. The electrodes of both substrates are aligned and fixed, and a metal (for example, aluminum or silver) is vacuum-deposited from the back surface. As a result, the electrode pattern and the organic EL element are electrically connected.
Further, the metal adhering to the back surface does not conduct to the internal electrode pattern by the partition 41, and only the electrode pattern and the element conduct. However, when the metal adhering to the back surface is removed after being deposited, it is not necessary to form a partition. The adhered metal may be peeled off mainly by a physical method, or may be peeled off by a lift-off method by providing a weak adhesive layer on the back surface of the substrate.

On the other hand, an element having a switching function as well as a simple electrode pattern can be formed on the back plate. In the case of the present invention, since an element having a switching function can be manufactured completely separately from the organic EL element, the substrate temperature can be set high, and a high-performance element of amorphous silicon or polysilicon can be manufactured. in this case,
Since an opening is not required, a relatively large area is allocated to the switching element portion, so that the switching element can withstand a large current drive, and has excellent characteristics and a high yield. The display of the element can be performed by constant voltage or constant current driving using these driving devices. For driving, any driving signal such as a pulse signal, a reverse bias signal, a step signal, a sawtooth signal, and a stray capacitance discharge can be obtained.

The driving method of the light emitting element can be classified according to the driving electrode. That is, numerical display, analog
Examples include segment display suitable for bar graph display, symbol display, fixed pattern display suitable for pattern display, character display, graphic display, and matrix display suitable for video display. In the matrix display, an anode and a cathode constitute a strip row electrode or the other strip column electrode, respectively, and an arbitrary pattern can be displayed by selectively applying a voltage to an arbitrary intersection. The driving method is applied to a case where a relatively large number of segment electrodes are used as in the case of a static drive in which segment electrodes to be displayed are individually and simultaneously driven, a large number of digits are displayed, or a matrix electrode configuration. Multiplex drive (line-sequential drive), and active elements that add and integrate switch elements and capacitor elements as necessary for each pixel at the intersection of the scanning electrode and signal electrode matrix to improve display characteristics such as contrast and response Matrix driving is mentioned. A particularly preferable driving method is not limited because an appropriate driving method differs depending on the application. For example, in the case of a small display using matrix driving, a line sequential driving method having a simple structure can be cited as a preferable example. Further, in order to emit light only in a predetermined region, the anode or the cathode can be processed into a predetermined shape, and can emit light in that shape, or can be used as a planar light emitting body. Further, any one of a direct current, an alternating current, and a pulse power source may be used for driving the element of the present invention.

The driving circuit may be separately manufactured and connected to the electrodes of the panel of the present invention. However, if the driving circuit is formed in advance on the back substrate or the organic EL manufacturing substrate using polysilicon or the like, the driving circuit of the panel can be formed. Even if the drive LSI is thinner than the drive LSI, no problem occurs, and it is not necessary to consider a thin LSI.

The characteristics of the device of the present invention are stabilized by the aging treatment. The aging process uses a DC constant current (voltage), a constant current (voltage) pulse, an alternating current, a stepped current (voltage), a gradually increasing current (voltage), a gradually decreasing current (voltage), and the like. The constant current processing is the most preferable example in terms of being able to maintain a high level and simplicity of the processing. Although the processing time is not particularly limited, it is desirable to end the processing when the luminance decrease during aging becomes gentle. This is often
This is because the element is stabilized when the change in luminance becomes gentle, so that the stop of light emission due to short-circuiting of luminance or short-circuiting during long-term driving is suppressed.

[0035]

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 (1) Preparation of Organic EL Element Substrate One side of an alkali-free glass (7059, manufactured by Corning Incorporated) having a length of 18 cm and a width of 23 cm was polished to a plate thickness of 1.1 ± 0.2.
It was adjusted to 05 mm (during dial gauge measurement). After cleaning the glass substrate, ITO was formed to a thickness of 135 nm by sputtering, and the resistance at that time was 15 Ω /
It was □. On this ITO substrate, 640 stripes having a pitch of 300 μm (line width 250 μm) were formed in the vertical direction. The ITO substrate is spin-coated with a paste obtained by dispersing carbon powder insulated in a photosensitive polyimide, prebaked at 140 ° C., and then exposed, developed, and cured with a 2 μm register between the ITO strips. Thus, an insulating resin black matrix was formed. The thus prepared ITO substrate was washed in the order of surfactant, ultrapure water, isopropyl alcohol, and methanol. Prior to device formation, the substrate was subjected to UV-ozone cleaning, mounted in a vacuum evaporation machine, and reduced in pressure to 3 × 10 ⁻⁴ Pa. While rotating the substrate, at a substrate temperature of normal temperature, copper phthalocyanine was vapor-deposited in a thickness of 20 nm, and then bis (m-
Methylphenylcarbazole) at 100 nm and tris (8-hydroxyquinolinolato) aluminum complex at 1 nm.
Each of 00 nm was deposited over the entire display area. Next, in order to produce a negative electrode, the mask was switched to a cathode mask without breaking vacuum. The cathode mask is made of a material containing nickel and has been removed so that 480 lines can be formed at a pitch of 300 μm (line width 250 μm) in the lateral direction of the panel. However, this alone cannot maintain the shape of the mask. There is a reinforcement line to prevent disconnection. The mask is fixed with a magnet from the back side of the substrate to increase the adhesion to the deposition surface and prevent short-circuiting of the deposition electrode. After fixing in such a state, the lithium is heated to make the inside of the vacuum vessel a lithium vapor atmosphere, and the organic layer is exposed to a thickness of 0.5 nm by a film thickness monitor to dope lithium. Subsequently, a negative electrode having a thickness of 200 nm was formed on aluminum by a resistance heating method. Through the above steps, a substrate on the organic EL element side was first completed.

(2) Preparation of Back Substrate A polished 1 mm thick alumina substrate (length 16 cm, width 2
5 cm), an electrode pattern using a photosensitive conductive paste and a projection were formed. First, the photosensitive conductive paste contains 40% methacrylic acid (M) in γ-butyrolactone as a solvent.
AA), a copolymer consisting of 30% methyl methacrylate (MMA) and 30% styrene (St)
Glycidyl methacrylate (GM
The polymer (8 g) obtained by the addition reaction of A) was mixed, and heated to 80 ° C. with stirring to dissolve all the polymers homogeneously. Then, the solution was cooled to room temperature, and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone and 2,4-diethylthioxanthone were added in an amount of 20% based on the total amount of the polymer and the monomer. The resulting photopolymerization initiator was added and dissolved. Then, add 4
The mixture was passed through a 00 mesh filter and filtered to prepare an organic vehicle. Next, sudan (0.
01g) and isopropyl alcohol (IPA)
A dispersant was added to the solution dissolved in, and the mixture was stirred homogeneously with a homogenizer. Then, the conductive powder (spherical,
A having an average particle diameter of 3.3 μm and a specific surface area of 0.82 m ² / g
g powder) was added and uniformly dispersed and mixed, and then dried at a temperature of 150 to 200 ° C using a rotary evaporator to evaporate IPA. In this way, a powder in which the surface of the conductive powder was uniformly coated with a film of the ultraviolet absorber (so-called encapsulated) was produced. Conductive powder obtained by encapsulating the organic vehicle with an ultraviolet absorber,
Trimethylolpropane triacrylate (3 g), dibutyl phthalate (DBP, 7 g), 2,4-diethylthioxanthone (1.8 g), ethyl p-dimethylaminobenzoate (EPA, 0.9 g), 4 parts per polymer % of acetic acid 2- SiO ₂ (concentration: 15%) dissolved in (2-butoxyethoxy) ethyl, glass frit (composition ratio by weight: silicon dioxide (1.5), aluminum oxide (3.6), boron oxide ( 61.3), barium oxide (19.1), potassium oxide (9.8), sodium oxide (4.7)) (3 g) and a solvent were mixed and dispersed with three rollers to prepare a paste.

The paste was printed solid on an alumina substrate using a 325 mesh screen,
Hold for minutes and dry. The thickness of the coating film after drying is 13μ.
m. This coating film was exposed to ultraviolet light from the upper surface with an ultra-high pressure mercury lamp having an output of 500 mW / cm ² using a chromium mask so as to overlap in the same pattern as the negative electrode formed on the organic EL element substrate. Next, the film was developed by immersion in a 0.5% by weight aqueous solution of monoethanolamine maintained at 25 ° C., and the unexposed portion was washed with water using a spray. This was baked at 580 ° C. for 15 minutes in air to prepare an electrode conductor film. The electrode thickness after firing was 8 μm, and the specific resistance was 3.2 μΩ · cm.

On the obtained electrode, 640 × 480 columns having a height of 3 μm and having a center at a position coincident with the center position of each light-emitting pixel were formed in the same manner as the method of forming the cathode pattern.

(3) Laminating Step Under an argon atmosphere, the back substrate is overlaid on the cathode side so that the pixels of the organic EL substrate and the projections of the back substrate are aligned, and the periphery is sealed with epoxy resin. Was pasted.

The panel having undergone the above steps was connected to a drive circuit by a probe pin connector, and displayed characters in a line-sequential manner by a dual scan method, and measured with a luminance meter (BM-8, manufactured by Topcon Corporation). The maximum luminance unevenness was 15
%. In addition, since this panel was sealed using the rear substrate, the luminance was reduced by 5% at the same current value even after storage in the atmosphere for three months.

Example 2 One side of a non-alkali glass (7059, manufactured by Corning Incorporated) having a length of 18 cm and a width of 23 cm was polished to a thickness of 1.1 ± 0.2.
It was adjusted to 05 mm (during dial gauge measurement). After cleaning the glass substrate, ITO was formed to a thickness of 135 nm by sputtering, and the resistance at that time was 15 Ω /
It was □. 1920 stripes of this ITO substrate were formed at a pitch of 100 μm (line width 70 μm) in the vertical direction. The ITO substrate is spin-coated with a paste obtained by dispersing carbon powder insulated in a photosensitive polyimide, prebaked at 140 ° C., and then exposed, developed, and cured with a 2 μm register between the ITO strips. Thus, an insulating resin black matrix was formed. The thus prepared ITO substrate was washed in the order of surfactant, ultrapure water, isopropyl alcohol, and methanol. Prior to device formation, the substrate was subjected to UV-ozone cleaning, mounted in a vacuum evaporation machine, and reduced in pressure to 3 × 10 ⁻⁴ Pa. While rotating the substrate, at a substrate temperature of normal temperature, copper phthalocyanine was vapor-deposited in a thickness of 20 nm, and then bis (m-
Methylphenylcarbazole) was deposited over the entire display area. Next, a nickel-based shadow mask with a reinforcing wire drawn in a stripe shape such that every two ITO / organic layers were exposed without breaking the vacuum was aligned and fixed with a magnet from the back of the substrate. Here the screw (2-
Methylquinolinolato) -3-pyridinolate complex was co-evaporated so that the doping amount of perylene was 1% by weight, and 30 n
After forming a light emitting layer having a thickness of m, a bis (2-methylquinolinolato) -3-pyridinolate complex layer was formed to a thickness of 70 nm. Next, this mask was displaced by 100 μm, and the mask was fixed so that every second ITO / organic layer was exposed. A tris (8-quinolinolato) aluminum complex is co-evaporated so that the doping amount of 1,3,5,7-pentamethylpyrromethene-difluoroborate becomes 0.35% by weight, and a light emitting layer having a thickness of 30 nm is formed. Was formed, and a tris (8-quinolinolato) aluminum complex layer was formed to a thickness of 70 nm. Further, the mask was shifted by 100 μm, and the mask was fixed so that every second ITO / organic layer was exposed. Then, a tris (8-quinolinolato) aluminum complex layer is co-evaporated so that the doping amount of Solvent Red 196 becomes 0.5% by weight to form a light emitting layer having a thickness of 30 nm. 70 nm was formed. Next, in order to produce a negative electrode, the mask was switched to a cathode mask without breaking vacuum. The cathode mask is also made of a material containing nickel and is removed so that 480 lines can be formed at a pitch of 300 μm (line width 250 μm) in the lateral direction of the panel. Reinforcing lines are inserted to prevent disconnection. The mask is fixed with a magnet from the back side of the substrate to increase the adhesion to the deposition surface and prevent short-circuiting of the deposition electrode. After fixing to such a state, lithium is heated to make the inside of the vacuum container a lithium vapor atmosphere, and the organic layer is exposed to a film thickness of 0.5 nm by a film thickness monitor to dope lithium. Subsequently, a negative electrode having a thickness of 200 nm was formed on aluminum by a resistance heating method.

When the organic EL substrate obtained in this manner was bonded to the rear substrate manufactured in Example 1 by the same method and driven, a color display was obtained. And red,
For each of the green and blue colors, the maximum luminance unevenness measured by a luminance meter (BM-8, manufactured by Topcon Corporation) is suppressed to within 17%, and the luminance decrease at the same current value even after three months in the atmosphere is not limited. The color was also less than 6%.

Comparative Example A display was prepared in the same manner as in Example 1 except that the rear substrate was not used, and conduction with the drive circuit was established by the probe pin connector, and character display was performed line-sequentially by the dual scan method. However, the maximum luminance unevenness measured by a luminance meter (BM-8, manufactured by Topcon Corporation) was 60%. Further, when stored for 3 months in the atmosphere, no luminescence was observed anymore. .

[0045]

According to the present invention, in an organic EL display, display on a large area can be performed while suppressing luminance unevenness and heat generation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a light emitting layer of a monochrome display according to the present invention.

FIG. 2 is a configuration diagram of a light emitting layer of a stripe type color display according to the present invention.

FIG. 3 is a configuration diagram of a light emitting layer of a stripe type color display according to the present invention.

FIG. 4 is a configuration diagram of a light emitting layer of the delta type color display according to the present invention.

FIG. 5 is a configuration diagram of a light emitting layer of a stripe type color display in which a plurality of light emitting layers are shared in the present invention.

FIG. 6 is a structural view of a light emitting layer of a stripe type color display in which a plurality of light emitting layers are shared in the present invention.

FIG. 7 is a configuration diagram of a light emitting layer of a stripe type color display in which all light emitting layers are shared in the present invention.

FIG. 8 is a structural view of a light emitting layer of a stripe type color display in which all light emitting layers are shared in the present invention.

FIG. 9 is a configuration diagram of a color display having a stripe configuration according to the present invention.

FIG. 10 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 11 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 12 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 13 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 14 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 15 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 16 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of an organic EL element.

FIG. 17 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of the organic EL element.

FIG. 18 is a schematic diagram of a cross-sectional shape of a negative electrode and a back electrode pattern of an organic EL element.

FIG. 19 is a schematic diagram of a cross-sectional shape of an organic EL element having a protective layer and a back electrode pattern.

FIG. 20 is a schematic diagram of a cross-sectional shape of a back electrode substrate having via holes and an organic EL.

FIG. 21 is a schematic diagram of a cross-sectional shape of a back electrode substrate having via holes and an organic EL.

[Explanation of symbols]

1.7.31.33.63. Glass substrate 2.8.32. Positive electrode (ITO) 3.5.10.13.16.19.22.25. Green light-emitting layer 4.9.12.15.18.12.12.430. Red light emitting layer 6.11.14.17.20.23.26. Blue light emitting layer 27.29. Negative electrode 28. Back substrate 33.42. Electrode pattern 34. Conductive projection 37. Protective film 35.39. Organic EL device (including anode and cathode) Via hole 41. Partition wall 42. 43. A conductive substance that electrically connects the electrode pattern and the organic EL element Substrate on which partition walls were made

Claims (8)

[Claims] 1. A display in which a substance which emits light is present between an anode and a cathode, and elements which emit light by electric energy are arranged in a predetermined shape, wherein the cathode or the anode is arranged outside the substrate. Organic E, electrically connected to the electrode pattern formed thereon
L display. 2. A light emitting device comprising a transparent electrode, a hole transporting layer, a light emitting layer, an electron transporting layer if necessary, and a cathode are arranged in a predetermined shape, and a substrate having an electrode pattern formed on a cathode side is formed. The organic EL display according to claim 1, wherein the organic EL display is arranged and connected so that the electrode pattern and the cathode are electrically connected. 3. The organic EL display according to claim 1, wherein the light emitting element is formed in a lattice-shaped insulator opening. 4. The organic EL display according to claim 1, wherein cathodes of adjacent light-emitting elements are connected in one direction to form a stripe. 5. The organic EL display according to claim 1, wherein a conductive projection for contacting a cathode of the light emitting element is formed on the electrode pattern. 6. The substrate according to claim 1, wherein a via hole is formed in the substrate on which the electrode pattern is formed, and electrical conduction between the cathode of the light emitting element and the electrode pattern is made via the via hole. 4. The organic EL according to any one of 4.
display. 7. The organic EL display according to claim 1, wherein an element having a switching function is disposed on the substrate in correspondence with the electrode pattern and each light emitting element. 8. The organic EL display according to claim 2, wherein the light emitting element is sealed by laminating a substrate on which the light emitting element is formed and a substrate on which the electrode pattern is formed.