JP2000048954A - Manufacture of organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic electrolumunescent element having a luminescent layer with superior pattern precision, using a mask deposition method. SOLUTION: This manufacturing method includes a pattern process for patterning the first electrode 2 formed on a substrate 1, a process for forming a thin film layer 10, which contains two kinds or more of luminescent layers 6 respectively patterned corresponding to two kinds or more of luminescent colors, on the first electrode 2, and a process for forming the second electrode 8 on the thin film layer 10. At least one kind of the luminescent layer 6 out of two kinds or more of the luminescent layers 6 is patterned by a mask deposition method using at least two divided process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, a flat panel display, a backlight, a lighting, an interior, a sign, a signboard, an electrophotographic device, and the like.
The present invention relates to a method for manufacturing an organic electroluminescent device capable of converting electric energy into light.

[0002]

2. Description of the Related Art In recent years, researches on organic electroluminescent devices in which electrons injected from a cathode and holes injected from an anode recombine in an organic phosphor sandwiched between both electrodes to emit light have been actively conducted. It has become. This device has attracted attention because it is thin, emits light with high luminance under a low driving voltage, and emits multicolor light by selecting a fluorescent material.

[0003] It has been shown for the first time that an organic electroluminescent device emits light at high brightness at a low voltage by CWTang et al. Of Eastman Kodak Company (Appl. Phys. Lett., 51 (12) 913 (198).
7).). A typical configuration of the organic electroluminescent device shown here is a hole-transporting diamine compound by a vapor deposition method, 8-hydroxyquinoline aluminum as a light emitting layer, on a glass substrate on which an ITO transparent electrode film is formed, Mg: Ag was sequentially provided as a negative electrode, and green light emission of 1000 cd / m ² was possible at a driving voltage of about 10 V. Although the current organic electroluminescent device has a different configuration such as providing an electron transport layer in addition to the above-described device components, it basically follows the configuration of CWTang et al.

[0004] There are also active studies on utilizing these organic electroluminescent devices capable of emitting high brightness and multicolor light for display devices and the like. However, Nikkei Electronics 1996.1.29 (N
o.654) As pointed out in p.102, patterning of the device is one of the major problems. For example, in the case of a full-color display, red (R),
It is necessary to form green (G) and blue (B) light emitting layers. Conventionally,
Such patterning is achieved by a wet process typified by a photolithography method, but the organic film forming the organic electroluminescent element has poor durability against moisture, organic solvents, and chemicals. It is also disclosed that a device capable of a wet process can be obtained by devising an organic material as typified by JP-A-6-234969. However, in such a method, the organic material used for the device is limited. Will be done. Further, there is a similar problem in patterning an electrode on an organic layer necessary for a display element.

[0005] For these reasons, organic electroluminescent devices have conventionally been manufactured by a dry process typified by a vapor deposition method, and patterning has been often realized by using a mask vapor deposition method. That is, a shadow mask is arranged in front of the substrate of the element, and an organic layer or an electrode is deposited only on the shadow mask opening.

[0006]

However, in order to cope with a fine pattern, the remaining portion (mask portion) of the mask material sandwiched between the openings of the shadow mask becomes thin like a thread, resulting in insufficient strength. Therefore, the shape of the opening is deformed due to bending or the like. As a result, in the conventional method, as the pattern becomes finer, the precision of the pattern shape of the element tends to deteriorate.

An object of the present invention is to solve such a problem and to provide a method of manufacturing an organic electroluminescent device having a light emitting layer with good patterning accuracy by a mask vapor deposition method.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a step of patterning a first electrode formed on a substrate, and a step of patterning a first electrode formed of at least an organic compound. A method for manufacturing an organic electroluminescent device, comprising: a step of forming a thin film layer including the above light emitting layer on the first electrode; and a step of forming a second electrode on the thin film layer. Wherein at least one of the light emitting layers is divided into two or more steps by a mask vapor deposition method and patterned.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An organic electroluminescent device according to the present invention is a device in which a light emitting layer made of at least an organic compound exists between an anode and a cathode, and emits light by electric energy. It is composed of a cathode and a thin film layer including a patterned light emitting layer.

The method for producing an organic electroluminescent device of the present invention comprises:
A step of patterning a first electrode formed on a substrate, and forming a thin film layer comprising at least two kinds of light-emitting layers comprising at least an organic compound and corresponding to at least two kinds of emission colors on the first electrode; And forming a second electrode on the thin film layer.

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

Preferred transparent electrode materials include tin oxide,
Zinc oxide, indium oxide, indium tin oxide (hereinafter I)
TO) and the like. For the purpose of patterning, it is preferable to use ITO having excellent workability.

In the step of patterning the first electrode, a photolithography method involving wet or dry 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 striped electrodes arranged at regular intervals.

In order to reduce the surface resistance of the transparent electrode and to suppress the voltage drop, ITO may contain a small amount of metal such as silver or gold, and tin, gold, silver, zinc, indium, or the like. Aluminum, chromium, 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 power consumption of the device, it is desirable that ITO has low resistance. For example, an ITO substrate of 300Ω / □ or less (ITO substrate)
If it is a transparent substrate on which a thin film is formed), it functions as an element electrode, but at present, it is possible to supply an ITO substrate of about 100Ω / □, and therefore, it is particularly desirable to use a low-resistance product. The thickness of the ITO can be selected according to the resistance value, and is usually 100 to 300 nm. IT
The method of forming the O film is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

A feature of the method for manufacturing an organic electroluminescent device of the present invention is that a thin film layer including a light emitting layer made of at least an organic compound is formed on the first electrode patterned as described above. Is to pattern at least one of the two or more kinds of light emitting layers formed corresponding to the light emission colors by two or more mask deposition steps.

The organic electroluminescent device according to the present invention comprises:
An element that displays multicolor or full color that emits light of two or more kinds of emission colors. In the case of full color, the element has emission peak wavelengths in three regions of red (R), green (G), and blue (B). It has three types of light-emitting layers patterned corresponding to three light-emitting colors, and is characterized in that at least one of these three types of light-emitting layers is patterned by two or more mask deposition steps. In two or more deposition steps.

The thin film layers included in the organic electroluminescent device include 1) a hole transport layer / a light emitting layer, 2) a hole transport layer / a light emitting layer / an electron transport layer, 3) a light emitting layer / an electron transport layer, and 4) And e) a light-emitting layer in which the above-mentioned combined substances are mixed in a single layer. 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.

Since the organic electroluminescent device of the present invention has luminescent layers corresponding to two or more kinds of luminescent colors in the device, it must be patterned in order to clearly distinguish each luminescent region. When displaying full color, patterning is indispensable in order to form three light emitting layers having R, G, and B light emission peak wavelengths.
Note that R, G, and B in the present invention mean that the maximum peak wavelength in the emission spectrum is 570 to 700, respectively.
nm, 500 to 570 nm, and 400 to 500 nm. In order to realize high color reproducibility, in the CIE standard color system, for R, x ≧ 0.45 and y ≦ 0.50; For G, x ≦ 0.35 and y ≧ 0.5
For 0 and B, it is preferable to satisfy the conditions of x ≦ 0.30 and y ≦ 0.40. However, in the case where the emission spectrum is converted by a known technique such as a color filter method or a color conversion method and then extracted outside, it is sufficient that not the emission itself but the light extracted outside satisfies the above conditions.

The present invention is characterized in that at least one of the light emitting layers corresponding to the respective light emitting colors is subjected to a patterning step by a mask vapor deposition method in two or more steps. The light-emitting layer made of an organic compound is characterized by being patterned by a mask evaporation method using a shadow mask.In that step, a first evaporation step is performed using a shadow mask having a predetermined opening pattern,
The second and subsequent depositions are performed with the shadow mask or another shadow mask having the same opening pattern as the shadow mask installed at a position different from the position relative to the substrate in the first deposition step. Thus, a patterned light emitting layer is formed.

The light-emitting region of the organic electroluminescent device is composed of a first electrode patterned in a plurality of stripes arranged at regular intervals and a plurality of stripe-shaped electrodes intersecting with the first electrode and arranged at regular intervals. This is the portion where the second electrode patterned on the substrate overlaps. Since each of the stripe-shaped first and second electrodes intersects with each other, the light-emitting region is considered to be a region divided into a lattice. However, in order to exhibit the function as the light emitting layer, the light emitting layer may be formed on the first electrode and have a stripe pattern substantially matching the stripe pattern of the first electrode. Alternatively, the second electrode may have a stripe pattern substantially matching the stripe pattern. Normally, in the manufacturing process, the ITO transparent electrode which is to be the patterned first electrode formed in the form of a stripe is patterned in a stripe shape in substantially the same manner. For example, if the ITO transparent electrode is 10
When formed at a pitch of 0 μm with a line width of 70 μm and an interval of 30 μm, R corresponding to full-color display,
Three kinds of light emitting layers corresponding to three light emission colors having respective light emission peak wavelengths of G and B are R, G, B or R,
B and G are arranged and formed on the ITO transparent electrode so as to match the pitch of the ITO transparent electrode in this order.

The pitch indicates, for example, in the case of striped electrodes arranged at regular intervals, the interval between the center lines of adjacent stripe electrodes, and is provided at regular intervals in a shadow mask. In the case of a striped opening, it indicates the distance between the center lines of adjacent striped openings.

In the present invention, at least one of the R, G, and B light emitting layers is formed by two or more mask deposition steps. In some cases, the R light emitting layer is formed by two or more mask deposition steps. The G light emitting layer or the B light emitting layer is formed by repeating the mask vapor deposition step twice or more in the same manner, and the B light emitting layer or the G light emitting layer
It is formed by repeating the mask deposition step at least twice. In the case where the ITO electrode has the above-described size, the light emitting layer formed corresponding to one emission color has a pitch of 300 μm, and the line width of the light emitting layer is 70 μm, which completely covers the ITO transparent electrode, on both sides. Can be selected in a range up to 130 μm extending to the ITO transparent electrode. As described above, the light emitting layer is formed on the ITO transparent electrode as the first electrode and has a similar stripe pattern. However, when the second electrode is formed by patterning, the second electrode does not exist. The light emitting layer does not need to be present at the interval. Therefore, the first electrode is patterned into a plurality of stripe-shaped electrodes arranged at regular intervals, the light-emitting layer is patterned by aligning with the first electrode, and the second electrode is positioned relative to the first electrode. In the case of manufacturing an organic electroluminescent element that is patterned into a plurality of intersecting striped electrodes, the formed light emitting layer does not have a continuous pattern along the striped shape of the first electrode, and the That is, it may be divided at a portion serving as an interval. That is,
The light emitting layers can be arranged in a lattice.

Similarly to the first electrode patterned in a plurality of stripes at predetermined intervals, the matrix intersects with the second electrode patterned in a plurality of stripes at predetermined intervals to form a matrix. The intersection is usually formed at right angles, but is not limited thereto.

In the mask evaporation, the light emitting layer is patterned using a shadow mask having a plurality of stripe-shaped openings arranged at regular intervals. Since the present invention is characterized in that at least one kind of light emitting layer is divided into two or more steps and patterned, a portion serving as a mask portion is smaller than a shadow mask used for patterning in one step. Since the width is enlarged to twice or more, it is possible to suppress the deterioration of the patterning accuracy due to the deflection of the mask, which is the biggest problem of the mask evaporation method, and the deformation due to the insufficient mask strength. For example, according to the above-described size display, when the line width of the light emitting layer is 100 μm, the width of the mask opening is 100 μm. Since the pitch is 300 μm, the width of the mask portion is 200 μm in the case of the single vapor deposition process, but if the vapor deposition process is performed twice, the width of the mask portion is increased to 500 μm, and if the vapor deposition process is performed three times, Since it is enlarged to 800 μm, the strength of the mask portion is dramatically improved, and the effect of the present invention becomes clear. In this example, after the first deposition step, the shadow mask is moved in a direction orthogonal to the longitudinal direction of the stripe-shaped opening (or another shadow mask is set at this position), and the second and subsequent depositions are performed. In other words, using a shadow mask in which stripe-shaped (rectangular) openings are arranged in a lattice or checkered pattern, moving the shadow mask in the longitudinal direction of the openings to perform the second and subsequent depositions However, the strength of the shadow mask is dramatically improved, and the same effect can be obtained.

Performing the light emitting layer patterning in two or more steps as described above not only improves the strength by enlarging the mask portion of the shadow mask, but also greatly improves the durability of the shadow mask. Can produce effects. That is, advantages such as easy handling of the shadow mask and less deformation of the mask in the cleaning step with a solvent or a chemical solution are obtained. Furthermore, the enlargement of the mask portion improves the planarity of the shadow mask, and in the step of attaching the shadow mask to the substrate with a plate magnet, which will be described later, the effect of the magnetic force for the adhesion due to the enlargement of the mask portion is also increased. In addition, uniform adhesion between the substrate and the shadow mask is further improved, adhesion of the light emitting layer material to portions other than the openings is reduced, and the distinction between adjacent light emitting layer regions becomes clearer. Further, since the opening area is reduced, the thickness of the mask portion can be increased, which also improves the flatness and the effect of the magnetic force. Due to these various effects, the durability, handleability, flatness, and adhesion of the shadow mask are improved, so that the production efficiency of the mask vapor deposition step can be significantly increased.

As described above, the light emitting layer is formed in a stripe shape. However, since the light emitting layer may be divided at a portion corresponding to the interval between the second electrodes, there is a reinforcing line formed so as to cross the stripe-shaped opening of the mask. It is preferable to use a shadow mask. Such reinforcing lines can be provided corresponding to the pitch of the second electrode patterning, but may be provided every other or every two, and further provided at intervals of an integral multiple of the pitch. The number of the reinforcing wires is not limited as long as there are no reinforcing wires at intervals smaller than the pitch of the second electrodes. By using the shadow mask having the reinforcing lines as described above, the accuracy and strength of the mask can be increased, and the effect of the present invention can be further improved.

FIG. 1 shows a preferred example of a mask having a reinforcing line according to the present invention. A plurality of stripe-shaped openings 32 provided in the plane of the mask are present at predetermined intervals. Further, a reinforcing wire 33 formed so as to cross each opening is provided. This reinforcement line is the mask part 3
1 serves to prevent the shape of the opening from being moved from a predetermined position due to bending or the like. The width of the reinforcing line is not particularly limited, but a portion where the light emitting layer does not exist,
That is, the width is preferably smaller than the width of the non-light-emitting region in the organic electroluminescent device. Therefore, for example, in the case of having the above-described size, the width of the reinforcing wire is preferably smaller than 50 μm, and more preferably smaller than 30 μm.
Such a mask structure is only an example, and is not particularly limited.

In the present invention, the shape and size of the opening of the shadow mask used in the two or more patterning steps basically correspond to the patterning shape and size included in the organic electroluminescent device. The optimal size may be selected depending on the conditions. Although the plate thickness of the mask cannot be generally shown, in a mask having a fine pattern, if the plate thickness is considerably larger than the minimum width of the mask portion, it is difficult to obtain sufficient dimensional accuracy. Therefore, the plate thickness is preferably not more than twice the minimum width of the mask portion. It is preferable that the thickness of the mask portion is large from the viewpoint of durability and flatness, but when the thickness is large, the shadow of the evaporation source may be formed, and the thickness of the light emitting layer may be uneven. In order to increase the plate thickness, it is necessary to take measures such as making the side surfaces of the openings tapered.

Suitable materials for the shadow mask include metal materials such as stainless steel, copper alloy, iron nickel alloy and aluminum alloy, and various resin materials.
There is no particular limitation. When the strength of the mask is not sufficient due to the fine pattern and it is necessary to improve the adhesion of the organic electroluminescent device to the substrate by magnetic force, it is preferable to use a magnetic material as the mask material.
Its material is pure iron, carbon steel, W steel, Cr steel, Co
Hardened magnet materials such as steel and KS steel, MK steel, Alni
precipitation hardening magnet materials such as Co steel, NKS steel, Cunico steel, sintered magnet materials such as OP ferrite and Ba ferrite, various rare earth magnet materials represented by Sm-Co system and Nd-Fe-B system, silicon steel plate , Al-Fe alloy, Ni-Fe alloy (permalloy) and other metal core materials, Mn-Zn-based, Ni-Zn-based, Cu-Zn-based and other ferrite core materials, carbonyl iron, Mo permalloy,
A dust core material obtained by compression-molding fine powder such as sendust together with a binder is included. It is desirable to manufacture the mask from a material obtained by forming these magnetic materials into a thin plate shape, but a material obtained by mixing powder of the magnetic material into rubber or resin and forming the film into a film shape can also be used.

The method for producing the shadow mask is not particularly limited, and may be a mechanical polishing method, a sand blast method,
Although a method such as a sintering method or a laser processing method can be used, it is preferable to use an etching method, an electroforming method, or a photolithography method which is excellent in processing accuracy. Among them, the electroforming method is a particularly preferable method for producing a shadow mask because the mask portion can be relatively easily formed thick.

The organic electroluminescent device is formed on a transparent substrate. The material of the transparent substrate is not particularly limited, and a plastic plate or film such as polymethyl methacrylate or polycarbonate can be used. Most preferably, it is used. As the glass material, 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 the mechanical strength, 0.5 mm or more is sufficient.

As a substrate having an ITO transparent electrode film serving as a first electrode formed on a transparent substrate as described above, a commercially available product can be used and patterned by the photolithography method as described above.

The thin film layer including the light emitting layer is formed on the patterned ITO transparent electrode as the first electrode, and the structure is as described above. Since the hole transport layer formed first in contact with the ITO transparent electrode is formed in the entire region where the light emitting region exists, it is not necessary to perform patterning, and is formed by vapor deposition on the entire surface.

The hole transporting layer is formed of a hole transporting substance alone or a hole transporting substance and a polymer binder.
As the hole transporting substance, N, N'-diphenyl-N,
N'-di (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine (TPD) and N, N'-diphenyl-N, N'-dinaphthyl-1,1'-diphenyl-
Heterocyclic compounds such as triphenylamines represented by 4,4′-diamine (NPD), N-isopropylcarbazole, pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadiazole derivatives and phthalocyanine derivatives; In a polymer system, a polycarbonate or a polystyrene derivative having the monomer in a side chain,
Polyvinylcarbazole, polysilane, polyphenylenevinylene, and the like are preferable, but are not particularly limited.

The material of the light emitting layer formed by patterning on the first electrode is anthracene, pyrene, and 8-hydroxyquinoline aluminum, for example, bisstyrylanthracene derivative, tetraphenylbutadiene derivative, coumarin derivative, Oxadiazole derivatives,
A distyrylbenzene derivative, a pyrrolopyridine derivative, a perinone derivative, a cyclopentadiene derivative, a thiadiazolopyridine derivative, and a polymer system include polyphenylenevinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives. As the dopant to be added to the light emitting layer, rubrene, quinacridone derivative, phenoxazone derivative, DCM, DCJ, perinone, perylene derivative, coumarin derivative, diazaindacene derivative, and the like can be used.

In the case of a laminated structure in which an electron transport layer is formed,
Since this layer is formed in the entire region where the light emitting region exists,
It can be formed over the entire surface similarly to the hole transport layer. As the electron transporting substance, it is necessary 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. As materials satisfying such conditions, 8-hydroxyquinoline aluminum, hydroxybenzoquinoline beryllium, 2- (4-biphenyl)
Oxadiazole derivatives such as -5- (4-t-butylphenyl) -1,3,4-oxadiazole (t-BuPBD) and oxadiazole dimer derivatives having improved thin film stability , 3-Bis (4-t-butylphenyl-1,3,4-oxadizolyl) biphenylene (OX
D-1), 1,3-bis (4-t-butylphenyl-
1,3,4-oxadizolyl) phenylene (OXD-
7), triazole derivatives, phenanthroline derivatives and the like.

The above materials used for the hole transporting layer, the light emitting layer and the 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 ether, polybutadiene, hydrocarbon resins, ketone resins, phenoxy resins, polyurethane resins, and other solvent-soluble resins, phenol resins, xylene resins, petroleum resins,
Urea resin, melamine resin, unsaturated polyester resin,
It is also possible to use the resin dispersed in a curable resin such as an alkyd resin, an epoxy resin, and a silicone resin.

The organic layers such as the hole transporting layer, the light emitting layer and the electron transporting layer may be formed by resistance heating evaporation, electron beam evaporation, sputtering or the like. Although not particularly limited, an evaporation method such as resistance heating evaporation or electron beam evaporation is usually preferable in terms of characteristics. The thickness of the layer cannot be limited because it depends on the resistance value of the organic layer.
It is selected from between 1000 nm.

The cathode serving as the second electrode is not particularly limited as long as it can efficiently inject electrons into the light emitting layer of the device. Therefore, it is possible to use a low work function metal such as an alkali metal, but considering the stability of the electrode, platinum, gold,
Preferable examples include metals such as silver, copper, iron, tin, aluminum, magnesium and indium, and alloys of these metals with low work function metals. In addition, a stable electrode can be obtained while maintaining high electrode injection efficiency by doping the organic layer with a small amount of a low work function metal in advance and then forming a film of a relatively stable metal as a cathode. The method of making these electrodes is also resistance heating evaporation,
Dry processes such as electron beam evaporation, sputtering, and ion plating are preferred.

The electric energy mainly refers to a direct current, but a pulse current or an alternating current can also be used. The current value and the voltage value are not particularly limited. However, in consideration of the power consumption and life of the device, it is necessary to obtain the maximum luminance with the lowest possible energy.

According to the present invention, the light emitting layer is formed by a mask vapor deposition method using a stripe-shaped opening or a shadow mask having a reinforcing line crossing the stripe-shaped opening. A first electrode patterned in a stripe shape is formed. The shadow mask is closely placed on the surface of the substrate on which the hole transport layer is formed and vapor deposition is performed (FIGS. 2 and 3), or a spacer having at least a portion having a height exceeding the thickness of the thin film layer is formed on the substrate. It is formed by a method such as forming a shadow mask and depositing the shadow mask in close contact with the spacer layer (FIGS. 4 and 5). In the latter case, the shadow mask adheres to the spacer, so that the thin film layer is prevented from being damaged. Such a spacer is not limited to this, but is preferably formed at a portion of the interval between the second electrodes patterned in a stripe shape, and the interval between reinforcing lines formed on the shadow mask is preferably It is preferable that the distance be equal to an integral multiple of the spacer interval.

As the material of the spacer, known materials can be used. As the inorganic material, an oxide material such as silicon oxide,
Glass materials, ceramic materials, and the like, and organic materials such as polyimide-based polymer materials can be used. Furthermore, by giving a black matrix function that contributes to improving the display contrast by blackening the spacer,
The patterned first electrode can be formed so as to cover the edge portion thereof, and can provide a function as an edge protection layer for preventing a short circuit between the first electrode and the second electrode. When an inorganic material is used, a method using a dry process such as resistance heating evaporation, electron beam evaporation, or sputtering evaporation is used.When an organic material is used, spin coating, slit die coating, or dip coating is used. Although there is a method using a wet process such as this, it is not particularly limited. The patterning method of the spacer is not particularly limited, but a method of forming a spacer layer on the entire surface of the substrate after the patterning step of the first electrode and patterning the spacer layer by using a known photolithography method is easy in process. The spacer may be patterned by an etching method using a photoresist or a lift-off method, or may be patterned by imparting photosensitivity to a polymer material, using a photosensitive spacer material, and exposing and developing a spacer layer. .

The first electrode patterned as described above is formed, and a thin film layer is formed on the substrate on which the spacer is formed. First, a hole transporting layer is formed. In this case, as shown in FIG. 6, a hole transporting material may be deposited on the entire region where the light emitting region exists.

As the next step, a shadow mask (FIG. 1)
The light emitting layer is patterned by using. An opening 32 having a shape corresponding to the light emitting layer pattern of the shadow mask is provided, and a reinforcing line 33 formed in the same plane as the mask portion so as to cross the opening to prevent deformation of the opening shape. Exists. Further, the shadow mask is fixed to a frame 34 for easy handling.
Next, a light emitting material is deposited as shown in FIGS. 2 and 3 or FIGS. In the latter case, the shadow mask is brought into close contact with the spacer 4 while aligning the position of the first electrode and the opening so that the reinforcing wire 33 overlaps the spacer 4. That is, the reinforcing wire comes into contact with the spacer. In this state, a light emitting material is deposited to form a light emitting layer 6 in a desired region. The present invention is characterized in that at least one of the two or more kinds of light emitting layers is formed by performing this operation twice or more while changing the relative position between the shadow mask and the substrate.

In some cases, an electron transport layer is formed as a structure of the thin film layer. In this case, like the hole transport layer, an electron transport material is vapor-deposited over the entire region where the light emitting region is present. To form Further, in the light emitting layer patterning step shown in FIG. 2 and FIG. 3 or FIG. 4 and FIG. 5, by continuously depositing an electron transporting material, as shown in FIG. Patterning is also possible.

Since the method of patterning the second electrode is not limited, a method using a so-called partition method may be used, or a method using a shadow mask may be used. In the case of using a shadow mask,
Although the shadow mask to be used is not particularly limited, examples of shadow masks that can be preferably used are shown in FIGS. In this shadow mask, an opening 32 having a shape corresponding to the second electrode pattern is provided in the mask portion 31, and a reinforcing line 33 formed to cross the opening to prevent deformation of the opening shape is provided. Exists. In addition, the shadow mask has a frame 3 for easy handling.
4 is fixed. Next, as shown in FIG. 10 and FIG. 11, the shadow mask is brought into close contact with the spacer while the mask portion is positioned so as to overlap the spacer 4. In this state, a second electrode 8 is formed in a desired region by depositing a second electrode material. Since the second electrode material that has flown from the reinforcing line 33 side is deposited around the shadowed portion of the reinforcing line due to the presence of the gap 36, the second electrode material is deposited.
The reinforcing electrode does not separate the second electrode. The patterning of the second electrode can be performed in a single vapor deposition process, but is not particularly limited to the number of processes, and a plurality of shadow masks can be used or the position of one shadow mask and the substrate can be relatively determined. For example, the second electrode may be patterned in a plurality of vapor deposition steps by shifting the pattern.

The patterning of the light emitting layer and the patterning of the second electrode are based on a common technique in that the patterning step is performed using a shadow mask having a reinforcing line in the opening, but the reinforcing line exists on the same plane. The shadow mask used for the second electrode patterning is different from the shadow mask for the light emitting layer in that a reinforcing line is formed outside the mask portion as shown in FIG. For this reason, in the patterning of the second electrode, the gap 36 shown in FIG. 9 is formed, and the wraparound deposition below the reinforcement line can be performed.

In the organic electroluminescent device, after the step of patterning the second electrode, if necessary, a protective layer may be formed or the light emitting region may be sealed using a known technique.

[0049]

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 A stripe-shaped opening as shown in FIG. 1 was used for patterning the light-emitting layer, and a reinforcing line was formed so as to cross the opening. The mask and the reinforcing line were 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. 136 stripe-shaped openings 32 having a length of 64 mm and a width of 100 μm are arranged at a pitch of 600 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 unnecessary portions of the ITO were removed 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 70 μm. As shown in FIG. 14, 816 first electrodes 2 patterned in the form of stripes are arranged at a pitch of 100 μm.

The pattern I formed with the first electrode
A spacer is formed on the TO substrate as follows.
Polyimide photosensitive coating agent (UR, manufactured by Toray Industries, Inc.
-3100) is applied on the ITO substrate by spin coating, and then is applied in a clean oven under a nitrogen atmosphere.
Prebaked at 1 ° C. for 1 hour. Next, this coating film was subjected to pattern exposure through a photomask to light cure the desired portion, and developed using a developer (DV-505, manufactured by Toray Industries, Inc.). Thereafter, baking was performed at 180 ° C. for 30 minutes and further at 250 ° C. for 30 minutes in a clean oven to form a spacer 4 orthogonal to the first electrode, as shown in FIG. This translucent spacer has a length of 90
mm, the width is 50 μm, and the height is 4 μm, and 201 are arranged at a pitch of 300 μm. Further, this spacer had good electric insulation.

The ITO substrate on which the above spacers were formed was washed, subjected to UV-ozone treatment, and then set in a vacuum deposition 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 deposition 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, in the arrangement as shown in FIG. 6, copper phthalocyanine was deposited to a thickness of 20 nm and bis (N-ethylcarbazole) was deposited to a thickness of 120 nm on the entire substrate to form a hole transport layer 5.

Next, a shadow mask for a light emitting layer was arranged in front of the substrate and brought into close contact with each other, and a ferrite plate magnet (YBM-1B, manufactured by Hitachi Metals, Ltd.) was arranged behind the substrate. At this time, the stripe-shaped first electrode is positioned at the center of the stripe-shaped opening of the shadow mask, the reinforcing line coincides with the position of the spacer, and the two are aligned so that the reinforcing line and the spacer are in contact with each other. In this state, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVB
i) was deposited to a thickness of 30 nm, and the first patterning of the B light-emitting layer was performed. Next, the relative position between the shadow mask and the substrate was shifted by 300 μm in the width direction of the stripe-shaped electrode, and then DPVBi was deposited to a thickness of 30 nm to perform the second patterning of the B light emitting layer.

In the same manner as the patterning of the B light emitting layer, an 8-hydroxyquinoline aluminum complex (Al
q ₃ ) was evaporated to a thickness of 30 nm, and the G light-emitting layer was divided into two steps and patterned. Further, by the same process, 1w
t% of 4- (dicyanomethylene) -2-methyl-6
(P-dimethylaminostyryl) -4-pyran (DC
M) -doped Alq ₃ was deposited to a thickness of 30 nm, and the R light emitting layer was divided into two steps and patterned.

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 deposition 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 disposed in front of the substrate so that both were brought into close contact with each other, and a plate magnet was disposed behind the substrate. At this time, FIG.
As shown in FIG. 11 and FIG. 11, the two are aligned so that the spacer 4 coincides with the mask portion 31. In this state, the second electrode 8 was patterned by depositing aluminum to a thickness of 400 nm. The striped second electrode had a sufficiently low electrical resistance over the length direction of 100 mm without being separated by the reinforcing lines of the shadow mask.

As described above, as schematically shown in FIGS. 16 to 18, the width is 70 μm, the pitch is 100 μm, and the number of pieces is eight.
A thin film layer 10 including a patterned RGB light emitting layer 6 is formed on the 16 ITO striped first electrodes 2, and a striped second electrode 8 having a width of 250 μm and a pitch of 300 μm is orthogonal to the first electrodes. Were arranged to produce a simple matrix type color light emitting device. R
Since the three light emitting regions of GB form one pixel,
This light emitting element has 272 × 200 pixels at a pitch of 300 μm.

The light emitting area of the present light emitting element is 70 × 250 μm.
, And emitted light uniformly in RGB independent colors.
Further, no decrease in the emission color purity of the light emitting region due to the wraparound of the light emitting material during the patterning of the light emitting layer was observed.

When the light emitting device was driven line-sequentially, clear pattern display and multi-color display were possible.

When the same process as in this embodiment is repeatedly performed by using the same shadow mask, no defect such as a decrease in emission color purity is observed, and the life and durability of the shadow mask are improved. It was recognized that.

Example 2 A shadow mask for patterning a light-emitting layer was prepared as shown below, and a light-emitting layer corresponding to each color of RGB was formed by dividing it into three evaporation steps. The method for forming each light emitting layer was performed in accordance with Example 1.

The shadow mask for light emitting layer patterning is
It has a reinforcing line formed so as to cross the stripe-shaped opening similar to FIG. 1 and has an outer shape of 120 × 84 m.
m, the thickness of the mask portion is 25 μm, and the length is 64 m
m, 100 μm wide stripe-shaped openings with a pitch of 900
91 μm are arranged. In each stripe-shaped opening, a reinforcing line having a width of 20 μm orthogonal to the opening is 900 μm.
It is formed with a pitch. Further, the shadow mask is fixed to a stainless steel frame having the same outer shape and a width of 4 mm.

The patterning of the ITO transparent electrode was carried out in Example 1.
The first electrode patterned in a stripe shape having a length of 90 mm and a width of 70 μm has a pitch of 100
816 lines are arranged in μm.

The formation of the spacer was performed in the same manner as in Example 1. 90mm length, 50μ width orthogonal to the first electrode
201 pieces are arranged at m, height 4 μm, and pitch 300 μm.

Processing of an ITO substrate on which a spacer is formed,
The setting in the evaporator, the conditions for forming the thin film layer, the conditions for forming the second electrode, and the like are the same as in Example 1.

After forming the hole transport layer on the entire surface of the substrate, the first patterning of the G light emitting layer was performed in the same manner as in Example 1 except that the above-described shadow mask for the light emitting layer was used. Next, the relative position between the ITO substrate and the shadow mask is moved by 300 μm, and the same patterning as the first time is repeated, and the second patterning of the G light emitting layer is performed. Further, the relative position between the ITO substrate and the shadow mask was moved by 300 μm to perform the third patterning of the G light emitting layer.

For the R and B light emitting layers, the light emitting layer material of Example 1 was patterned in three vapor deposition steps in accordance with the method for forming the G light emitting layer.

Thereafter, an electron transport layer was formed on the entire surface of the substrate in the same manner as in Example 1.

The patterning of the second electrode was performed in the same manner as in Example 1, and the width was 70 μm, the pitch was 100 μm, and the number was 816.
A patterned RGB light emitting layer is formed on the ITO striped first electrode, and has a width 2 orthogonal to the first electrode.
A simple matrix type color light-emitting element in which 200 stripe-shaped second electrodes having a pitch of 50 μm and a pitch of 300 μm were arranged was manufactured. Since the three light-emitting regions of RGB form one pixel, the present light-emitting element has a pitch of 300 μm and 273 ×
It has 200 pixels.

Although the vapor deposition process of one light emitting layer is divided into three times, since the accuracy and strength of the shadow mask are remarkably improved, a reduction in color purity due to color mixing of luminescent colors and the shape of the opening caused by repeated use are caused. Therefore, the occurrence of defects due to fluctuations in the color can be reduced, so that color light emitting elements can be produced with high yield.

Example 3 Example 1 was repeated except that the spacer was 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 obtain a black spacer. This spacer has a length of 9
0 mm, width 50 μm, height 2 μm, pitch 300
201 pieces are arranged in μm.

The color light emitting device produced by repeating Example 1 clearly shows a pattern display similarly to the device obtained in Example 1, and has a black spacer formed around the light emitting region. Since it functions as a black matrix, the display contrast is higher than that of the device obtained in Example 1.

Example 4 Example 1 was repeated except that the step of forming the spacer was omitted. In the light-emitting layer patterning using a shadow mask because there is no spacer, the shadow mask contacts the thin film layer formed before the process, but defects are generated in the thin film layer by carefully performing the shadow mask alignment process Without performing, patterning of each of the RGB light emitting layers and patterning of the second electrode could be performed. When the obtained simple matrix organic electroluminescent device was driven to emit light by line-sequential driving, clear display was possible.

COMPARATIVE EXAMPLE 1 For patterning the light emitting layer, a shadow mask having reinforcing lines formed so as to cross the stripe-shaped openings similar to those shown in FIG. 1 was prepared. The outer shape of the shadow mask is 120 × 84 mm, and the thickness of the mask portion is 2
272 stripe-shaped openings having a length of 5 μm, a length of 64 mm and a width of 100 μm are arranged at a pitch of 300 μm. Each stripe-shaped opening has a width 2 orthogonal to the opening.
Reinforcing lines having a thickness of 0 μm and a thickness of 25 μm are formed at 1.8 mm intervals.

The shadow masks have the same outer shape and a width of 4 mm.
Fixed to a stainless steel frame.

The patterning of the first electrode, the formation of the spacer, and the formation of the hole transport layer were performed in the same manner as in Example 1, and then
Using the shadow mask of this comparative example, each of the RGB light emitting layers was formed by one patterning. After that, the formation of the electron transport layer and the patterning of the second electrode are performed,
A simple matrix type color light emitting device having 72 × 200 pixels was manufactured.

The light emitting area of this light emitting device is 70 × 250 μm.
And emitted light uniformly in colors independent of RGB. However, since the light-emitting material slightly wraps around during the patterning of the light-emitting layer, a decrease in the color purity of the emitted light was observed in some light-emitting regions.

In the shadow mask for patterning a light emitting layer of the present invention shown in Example 1 where at least one kind of light emitting layer is patterned by two or more steps, 10
Although there is a mask portion of 500 μm in the opening of 0 μm, in the shadow mask for patterning one light emitting layer in one process used in this comparative example, the mask portion is 200 μm for the opening of 100 μm. Therefore, the strength and flatness of the entire mask are inevitably inferior in the latter, and there is a possibility that the shape of the opening may be deformed or the adhesion may be poor due to repeated use, and the above-mentioned causes of the decrease in color purity. Becomes

[0086]

According to the present invention, there is provided a process for forming a thin film layer comprising at least two kinds of luminescent layers, which comprises at least an organic compound of an organic electroluminescent device and is patterned corresponding to at least two kinds of luminescent colors. The method is characterized in that at least one of the two or more light emitting layers is divided into two or more steps by a mask vapor deposition method and patterned. Thus, the patterning step of one light emitting layer is performed in two steps.
By dividing the number of times, the strength, flatness, handling, and adhesion of the shadow mask used are improved, so that the durability of the shadow mask is improved and the element production efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a shadow mask for patterning a light emitting layer used in the present invention.

FIG. 2 is a sectional view taken along the line XX ′ for explaining an example of a light emitting layer patterning method according to the present invention.

FIG. 3 is a sectional view taken along the line YY ′ for explaining an example of a light emitting layer patterning method according to the present invention.

FIG. 4 is a sectional view taken along the line XX ′ for explaining another example of the light emitting layer patterning method according to the present invention.

FIG. 5 is a YY ′ sectional view for explaining another example of the light emitting layer patterning method according to the present invention.

FIG. 6 is an XX ′ cross-sectional view illustrating a method for forming a hole transport layer.

FIG. 7 shows X showing an example of a patterned electron transport layer.
X 'sectional view.

FIG. 8 is a plan view showing an example of a shadow mask for patterning a second electrode.

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

FIG. 10 shows X showing an example of a second electrode patterning method.
X 'sectional view.

FIG. 11 is a YY showing an example of a second electrode patterning method.
Sectional view.

FIG. 12 is a plan view showing another example of the shadow mask for patterning the second electrode.

FIG. 13 is a sectional view taken along the line XX ′ of FIG. 12;

FIG. 14 is a plan view showing an example of a first electrode pattern.

FIG. 15 is a plan view showing an example of a spacer.

FIG. 16 is a plan view showing an example of the organic electroluminescent device manufactured by the present invention.

FIG. 17 is a sectional view taken along the line XX ′ of FIG. 16;

18 is a sectional view taken along line YY 'of FIG.

DESCRIPTION OF SYMBOLS 1 Substrate 2 First electrode 4 Spacer 5 Hole transport layer 6 Light emitting layer 7 Electron transport layer 8 Second electrode 10 Thin film layer 30 Shadow mask 31 Mask portion 32 Opening 33 Reinforcement line 34 Frame 35 Mask portion One side 36 gap

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 6, 1999 (1999.7.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction contents]

[0056] First, in the arrangement shown in FIG. 6, water
Values of copper phthalocyanine of 20 nm and bis (N-ethylcarbazole) of 12
The hole transport layer 5 was formed by vapor deposition on the entire surface of the 0 nm substrate.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB04 AB06 AB18 BA06 CB01 CC04 DA01 DB03 EB00 FA01 5C094 AA42 AA43 BA29 CA24 GB01

Claims (7)

[Claims] A step of patterning a first electrode formed on a substrate; and a step of patterning at least two kinds of luminescent colors, each of which is made of an organic compound.
A method for manufacturing an organic electroluminescent device, comprising: a step of forming a thin film layer including at least one kind of light emitting layer on the first electrode; and a step of forming a second electrode on the thin film layer. A method for manufacturing an organic electroluminescent device, wherein at least one of the above light emitting layers is divided into two or more steps by a mask deposition method and patterned. 2. A method in which at least one of three kinds of light emitting layers patterned respectively corresponding to three light emission colors having light emission peak wavelengths in red, green and blue regions is subjected to two or more steps by a mask vapor deposition method. 2. The method for manufacturing an organic electroluminescent device according to claim 1, wherein the pattern is divided and patterned. 3. The three kinds of light-emitting layers are red, green, blue or red,
3. The method for manufacturing an organic electroluminescent device according to claim 2, wherein patterning is performed in a shape repeated at a constant pitch in the order of blue and green. 4. A first vapor deposition step using a shadow mask, and the shadow mask or another shadow mask having the same opening pattern as the shadow mask is positioned relative to the substrate in the first vapor deposition step. 2. The organic electroluminescent device according to claim 1, wherein one type of light emitting layer is patterned in two or more steps by performing the second and subsequent evaporations in a state where the organic electroluminescent element is installed at a position different from the position. Production method. 5. A first electrode is patterned into a plurality of striped electrodes arranged at intervals, the light emitting layer is patterned by positioning with the first electrode, and a second electrode is formed on the first electrode. 2. The method according to claim 1, wherein patterning is performed on a plurality of striped electrodes crossing each other. 6. The method according to claim 1, wherein the light emitting layer is patterned by using a shadow mask having a plurality of stripe-shaped openings arranged at intervals. 7. The method for manufacturing an organic electroluminescent device according to claim 6, wherein a shadow mask having reinforcing lines formed so as to cross the stripe-shaped openings is used.