JP2000208254A - Method for manufacturing organic EL element and organic EL display device - Google Patents

Abstract

(57) [Summary] In a method of manufacturing an organic EL element using a conventional coating method, phase dissolution occurs when an organic layer is laminated, resulting in poor luminous efficiency and low color purity of an organic EL display device. Poor and poor pattern accuracy were problems. After a silane coupling agent is put into a hole injection layer and cross-linked, a red and green light emitting layer is conjugated by heating a PPV precursor solution after forming a pattern using an ink jet. A blue light emitting layer is formed on the entire surface by a coating method. A cathode is also formed over the entire surface to provide a display device driven by a TFT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic EL device used for a display section of information equipment such as a television and a computer, and electric and electronic products, and an organic EL display device.

[0002]

2. Description of the Related Art In recent years, the development of an electroluminescent device using an organic material as a light-emitting display replacing a liquid crystal display has been accelerated. As an organic EL device using an organic substance,
Appl. Phys. Lett. 51 (12), 21
Sep. 1987, page 913, a method of forming a low molecular weight film by a vapor deposition method;
pl. Phys. Lett. 71 (1), 7 July
As shown in page 34 of 1997, a method of applying a polymer is mainly developed. In particular, by using the inkjet method when colorizing polymer systems,
It is attracting attention because it can be easily patterned. When this polymer is used, a hole injection layer or a hole transport layer is often formed between the anode and the light emitting layer. Conventionally, a conductive polymer, for example, a polythiophene derivative or a polyaniline derivative has been often used for the buffer layer or the hole injection layer. In a low molecular weight system, a phenylamine derivative was often used as a hole injection layer or a hole transport layer.

As disclosed in Japanese Patent Application Laid-Open No. 10-153967, a method has been proposed in which a light-emitting layer is formed by a patterning method using a high-molecular-weight material by an ink-jet method and a lamination structure using a low-molecular-weight material by an evaporation method. I have.

In the formation of a polymer layer, application and patterning can be performed at one time by the ink jet method. In addition, the materials used can be minimized. On the other hand, in other coating methods, a simple machine such as a spin coater may be used.

[0005]

However, when patterning and laminating using a conventional coating method, there is a problem of so-called compatibility in which the solvent of the coating solution dissolves the already formed organic film. A multilayer structure for increasing the luminous efficiency cannot be obtained, resulting in a non-uniform continuous film, causing a significant decrease in the luminous efficiency, and in some cases, no light emission. Specifically, a hole injection layer or a hole transport layer and a red or green light emitting layer, and a red or green light emitting layer and a blue light emitting layer. Further, phase dissolution occurs between the hole injection layer or the hole transport layer and the blue light emitting layer.

Further, the dopant added to shift the emission wavelength does not function effectively because the films are mixed, and the emission color does not change even if two or more liquids are patterned. there were.

Accordingly, an object of the present invention is to form a multi-layer structure as designed without forming a phase-solubilization between the organic layers when forming all the organic layers by a coating method. Higher efficiency, higher color purity,
It is an object of the present invention to provide a higher-definition organic EL display device, and to provide a manufacturing method capable of increasing the productivity and increasing the screen size.

[0008]

Means for Solving the Problems Means for Solving the Problems The method for manufacturing an organic EL device according to the present invention is directed to a method for manufacturing an organic EL device having a structure in which a hole injection layer or a hole transport layer and a light emitting layer are sandwiched between an anode and a cathode. A step of forming an electrode, a step of forming a hole injection layer or a hole transport layer made of an organic compound, a step of patterning a red and green light-emitting layer made of an organic compound by an inkjet method, and a step of forming an organic compound It comprises a step of forming a blue light-emitting layer by a coating method and a step of forming a cathode.
With this configuration, all the organic layers can be formed by a coating method.

Means for solving the problem Means 1 for solving the above-mentioned problems is characterized in that a separation film covering other than pixels is provided on the substrate. With this configuration,
Multicolor high definition can be easily achieved.

Means for solving the problem In the means (1) or (2) for solving the above-mentioned problem, a liquid containing at least a polythiophene derivative and a silane coupling agent is formed into a film by a coating method and thermally cured to form the hole injection layer or the hole transport layer. It is characterized by the following. With this configuration, a hole injection layer or a hole transport layer having an appropriate ionization potential that is not compatible with the light emitting layer can be easily formed.

Means for solving the problem 4. In the means 1 or 2 for solving the above-mentioned problem, a liquid containing at least a polythiophene derivative and a silane coupling agent is formed on an anode of a pixel portion by an ink jet method, and is thermally cured to form the hole injection layer or It is characterized in that a hole transport layer is formed. With this configuration, a hole injection layer or a hole transport layer having an appropriate ionization potential and having an appropriate ionization potential can be easily formed only in a pixel portion by controlling the film thickness accurately.

Means for solving the problem In the means 1 to 4 for solving the above problems, a liquid containing at least a precursor of polyparaphenylene and a derivative thereof is formed into a film by an inkjet method, and the liquid is heated and conjugated to form the red and green light emitting layers. It is characterized by forming. According to this configuration, a red and green light-emitting layer having high efficiency and high color purity, which is incompatible with the hole injection layer or the hole transport layer and the blue light-emitting layer, can be easily formed.

Means for solving the problem In means 1 to 5 for solving the above-mentioned problems, a blue light-emitting layer is
It is characterized by being formed by applying a liquid in which at least a polyfluorene derivative is dissolved and drying it. With this configuration, a blue light-emitting layer with high efficiency and high color purity, which is incompatible with the hole injection layer or the hole transport layer and the red or green light-emitting layer, can be easily formed.

Means for solving the problem7. Means 1 to 6 for solving the above problems are characterized in that after forming a hole injection layer or a hole transport layer on an anode, plasma of a fluorocarbon gas is irradiated, and then a light emitting layer is formed. With this configuration, a fluorinated layer can be easily formed on the hole injection layer or the hole transport layer. The energy level at the interface between the hole injection layer or the hole transport layer and the light emitting layer can be matched, so that the luminous efficiency can be improved and the driving voltage can be reduced.

Means for solving the problem In the means 1 to 6 for solving the above problems, a hole injection layer or a hole transport layer is formed on the anode, red and green light emitting layers are formed, and then a plasma of fluorocarbon gas is irradiated, and then light emission is performed. Forming a layer. With this configuration, a fluorinated layer can be easily formed on the hole injection layer or the hole transport layer and the red and green light emitting layers.

Means for solving the problem 9. Means 7 or 8 for solving the above-mentioned problem is characterized in that the fluorocarbon gas is CF4. With this configuration, a fluorinated layer can be more efficiently formed on the hole injection layer or the hole transport layer and the red and green light-emitting layers.

Means for Solving the Problems Means 7 or 8 for solving the above-mentioned problem is characterized in that oxygen plasma is irradiated before irradiation with fluorocarbon gas plasma. With this configuration, a fluorinated layer can be more efficiently formed on the hole injection layer or the hole transport layer and the red and green light-emitting layers.

Means for Solving the Problem The organic EL display device of the present invention is characterized by having an organic EL element produced by any one of the manufacturing methods of the means 1 to 10. With this configuration, an organic EL display device with high efficiency and high color purity and high definition can be provided.

Means for solving the problem Means 11 for solving the above-mentioned problems is characterized in that a TFT element for driving each pixel is formed on a transparent substrate. With this configuration, it is possible to provide a high-definition organic EL display device with a large screen, high efficiency and high color purity.

Means for Solving the Problems 13. The means for solving the above problem 11 is characterized in that a protective film is formed on a cathode. With this configuration, a highly reliable organic EL display device can be provided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an organic EL device and an organic EL device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

Embodiment 1 FIG. 1 shows a first embodiment of a method for manufacturing an organic EL device according to the present invention. FIG. 3 shows a method of manufacturing a three-color full-color organic EL device. As shown in the figure, pixel electrodes 101, 102,
103, forming a hole injection layer or a hole transport layer 120 made of an organic compound on each pixel electrode, and pattern-forming a red light emitting layer 106 and a green light emitting layer 107 made of an organic compound. A method for manufacturing an organic EL device, comprising: a step of forming a blue light-emitting layer 108 made of an organic compound; and a step of forming a cathode 113, wherein the formation of red and green light-emitting layers is performed by an inkjet method. It is characterized by.

The transparent substrate 104 functions not only as a support but also as a surface from which light is extracted. Therefore, the transparent substrate 104 is selected in consideration of light transmission characteristics, thermal stability, and the like. Examples of the transparent substrate material include a glass substrate and a transparent plastic, and a glass substrate is preferable because of its excellent heat resistance.

First, the pixel electrode 10 is placed on the transparent substrate 104.
1, 102 and 103 are formed. Examples of the formation method include photolithography, a vacuum evaporation method, a sputtering method, a pyrosol method, and the like, and it is preferable to use photolithography. A transparent pixel electrode is preferable as the pixel electrode, and examples of a material forming the transparent pixel electrode include a tin oxide film, an ITO film, and a composite oxide film of indium oxide and zinc oxide.

Next, a partition (bank) 105 is formed, and the space between the transparent pixel electrodes is filled. Thereby, it is possible to improve contrast, prevent color mixing of light emitting materials, and prevent light leakage between pixels.

The material constituting the partition 105 is EL
The material is not particularly limited as long as it has durability to the solvent of the material, and examples thereof include an organic material such as an acrylic resin, an epoxy resin, and photosensitive polyimide, and an inorganic material such as a liquid glass. Further, the partition wall 105 may be formed as a black resist by mixing carbon black or the like into the above material. Examples of a method for forming the partition 105 include photolithography.

Further, a hole injection layer or a hole transport layer 120 made of an organic compound is formed on each of the pixel electrodes. First, on a patterned transparent substrate 1 with a transparent anode,
After the oxygen plasma or UV irradiation treatment, a substance which can be a hole injection layer or a hole transport layer was formed. Examples in which a polythiophene derivative is contained as the hole injection layer or the hole transport layer have been described. As a polythiophene derivative, Baytron P sold by Bayer was used, and PSS (polystyrene sulfonic acid) was added as necessary.
As a silane coupling agent to be crosslinked, γ-glycidyloxypropyltrimethoxysilane was used. Appropriate amounts of methanol and ethoxyethanol were added as solvents, and this was spin-coated on a glass substrate on which a transparent electrode had been formed. Further, it was heated at 200 ° C. under vacuum for 1 hour. The cured hole injection layer or hole transport layer became insoluble in common solvents. The thickness was 200 nm.

Further, an organic light emitting layer is formed on each pixel electrode in a predetermined pattern. The organic light emitting layer is preferably provided in three colors, and among them, it is preferable to form red and green by an ink jet method.

In the embodiment of FIG. 1, the pixel electrodes 101, 10
2, a cured hole injection layer or hole transport layer 120
Through each of the red light emitting layers 1 by an ink jet method.
06 and the green light-emitting layer 107,
The mixture was heated at 0 ° C. under vacuum for 1 hour. The thickness was 100 nm.

Here, the ink jet system means that a luminescent material is dissolved or dispersed in a solvent and discharged as a discharge liquid from a head 110 of an ink jet printing apparatus 109, and at least one of three primary colors such as red, green and blue or intermediate colors thereof. This means that one color pixel is formed.

According to such an ink jet system, fine patterning can be performed easily and in a short time. Further, it is possible to easily and freely control the light emitting ability such as the color balance and the luminance by adjusting the film thickness by increasing or decreasing the ejection amount, or by adjusting the density of the ink.

When the organic light-emitting material is a conjugated polymer precursor described below, each light-emitting material is discharged and patterned by an ink jet method, and then the precursor components are conjugated by heating or light irradiation. Film) to form a light-emitting layer insoluble in common solvents.

The light emitting layer is preferably composed of an organic compound, and more preferably composed of a high molecular organic compound. By providing a light-emitting layer made of an organic compound, it is possible to achieve high-luminance surface light emission at a low voltage. Also, a wide selection of light emitting materials enables rational design of EL light emitting devices.

In particular, a high molecular weight organic compound is excellent in film-forming properties, and the durability of a light emitting layer composed of a high molecular weight organic compound is extremely good. Further, it has a forbidden band width in the visible region and relatively high conductivity, and the conjugated polymer is particularly prone to this tendency. As the organic light emitting layer material, a polymer organic compound itself, a precursor of a conjugated polymer organic compound which is conjugated (formed into a film) by heating or the like, or the like is used.

When the precursor before conjugation (film formation) is used as a light-emitting material, it is easy to adjust the surface tension, viscosity, etc., as an ink-jet discharge liquid, it is possible to perform precise patterning, and to form a light-emitting layer. Emission characteristics and film properties can be easily controlled.

The organic compound capable of forming the light emitting layer includes
For example, polyalkylthiophene such as PPV (poly (para-phenylenevinylene)) or a derivative thereof, PTV (poly (2,5-thienylenevinylene)), and PFV (poly (2,
5-furylenevinylene)), polyarylenevinylene such as polyparaphenylene, polyalkylfluorene, pyrazoline dimer, quinolidinecarboxylic acid, benzopyrylium perchlorate, benzopyranoquinolidine, rubrene,
Phenanthroline europium complexes and the like can be mentioned, and these can be used alone or in combination of two or more.

Among them, PPV or a derivative thereof which is a conjugated organic polymer compound is preferable. The precursor of PPV or its derivative before conjugation (film formation) is soluble in water or a polar organic solvent, and is suitable for pattern formation by an inkjet method. Further, since it is a polymer, a thin film having high optical quality and excellent durability can be obtained. Furthermore, PPV or a derivative thereof has strong fluorescence, and is a conductive polymer in which the π electron of the double bond is non-polarized on the polymer chain. Therefore, the PPV thin film also functions as a hole injection transport layer, A high-performance organic EL device can be obtained.

Further, when a polymer organic light emitting layer material is used, the composition for an organic EL device may contain at least one kind of fluorescent dye. This makes it possible to change the light-emitting characteristics of the light-emitting layer, and is effective as, for example, a means for improving the light-emitting efficiency of the light-emitting layer or changing the light absorption maximum wavelength (emission color).

That is, the fluorescent dye can be used not only as a light emitting layer material but also as a dye material having a light emitting function itself. For example, most of the energy of excitons generated by carrier recombination on conjugated polymer organic compound molecules such as PPV can be transferred to fluorescent dye molecules. In this case, since light emission occurs only from a fluorescent dye molecule having a high fluorescence quantum efficiency, the current quantum efficiency of the EL element also increases. Therefore, when a fluorescent dye is added to the composition for an organic EL device, the emission spectrum of the light emitting layer becomes the same as that of the fluorescent molecule, and this is also effective as a means for changing the emission color.

Here, the current quantum efficiency is a measure for considering the light emitting performance based on the light emitting function, and is defined by the following equation.

Η _E = emitted photon energy /
Input electric energy The conversion of the light absorption maximum wavelength by the doping of the fluorescent dye enables emission of red and green with high color purity, and as a result, a full-color display device can be obtained. Further doping with a fluorescent dye allows E
The luminous efficiency of the L element can be greatly improved.

As the fluorescent dye used in the red light emitting layer, DCM of laser dye, rhodamine or rhodamine derivative, perylene or the like can be used. Since these fluorescent dyes are low-molecular, they are soluble in a solvent, have good compatibility with PPV and the like, and can easily form a uniform and stable light-emitting layer. Examples of the rhodamine derivative fluorescent dye include rhodamine B, rhodamine B base, rhodamine 6G, and rhodamine 101 perchlorate, and a mixture of two or more of these may be used.

The fluorescent dye used in the green light-emitting layer includes quinacridone, rubrene, DCJT and derivatives thereof. These fluorescent dyes, like the red fluorescent dye described above, are low-molecular and soluble in solvents,
Further, it has good compatibility with PPV and the like, and easily forms a light emitting layer.

Next, as shown in FIG.
8 is formed on the red light emitting layer 106, the green light emitting layer 107 and the pixel electrode 103. As a result, three colors of red, green and blue
In addition to forming the primary colors, it is possible to fill the steps between the red light-emitting layer 106 and the green light-emitting layer 107 and the partition 105 and to planarize them. As a result, a short circuit between the upper and lower electrodes can be reliably prevented. By adjusting the thickness of the blue light emitting layer, the blue light emitting layer acts as an electron injection / transport layer in the stacked structure of the red light emitting layer and the green light emitting layer, and does not emit blue light.

The method for forming the blue light-emitting layer 108 is not particularly limited, and the blue light-emitting layer 108 can be formed by a general spin coating method or an ink-jet method as a wet method. In this embodiment, the blue light-emitting layer 108 was spin-coated with a polydioctylfluorene xylene solution and dried at 80 ° C. for 1 hour to have a thickness of 100 nm.

Other examples of the blue light-emitting layer include polydihexylfluorene, which is a polyfluorene derivative, and a copolymer with another polymer group, and a blue fluorescent dye or an organic compound having an electron injection / transport function is added. Is also good.

Examples of the organic compound capable of forming the electron injecting and transporting layer include oxadiazole derivatives such as PBD and OXD-8, DSA, aluminum quinolinol complex, Bebq, triazole derivative, azomethine complex, porphine complex, and benzooxydiazole complex. And the like.

As in the present embodiment, two colors of the organic light emitting layer are formed by the ink jet method, and the other color is formed by the conventional coating method. Also, a full-color organic EL element can be formed by combining with another organic light emitting material used for an ink jet system, so that the range of design is expanded. Conventional coating methods other than the inkjet method include a printing method, a transfer method, a dipping method, a spin coating method, a casting method, a capillary method, a roll coating method, a bar coating method, and the like.

Finally, a cathode (counter electrode) 113 is formed, and the organic EL device of the present invention is manufactured. The cathode 113 is preferably a metal thin-film electrode, and examples of the metal constituting the cathode include Mg, Ag, Al, and Li. In addition to these, a material having a small work function can be used. For example, an alkali metal, an alkaline earth metal such as Ca, and an alloy containing these can be used. Fluoride of metal is also applicable. Such a cathode 113 can be provided by an evaporation method, a sputtering method, or the like.

Further, a protective film 401 may be formed on the cathode 113 as shown in FIG. Protective film 401
Is formed, the cathode 113 and each light emitting layer 10 are formed.
6, 107, 108 can be prevented from being deteriorated, damaged, peeled off, and the like.

As a constituent material of such a protective film 401, an epoxy resin, an acrylic resin, a liquid glass or the like can be used. Examples of the method for forming the protective film 401 include a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, and a capillary method.

FIGS. 6 and 7 show the structure of an ink jet head used in the method for manufacturing an organic EL device of the present invention. The inkjet head 10 includes:
For example, a nozzle plate 11 and a diaphragm 13 made of stainless steel
And both are joined via a partition member (reservoir plate) 15.

A plurality of ink chambers 19 and liquid reservoirs 21 are formed between the nozzle plate 11 and the vibration plate 13 by the partition member 15. Ink chamber 19 and liquid pool 2
The inside of 1 is filled with the composition of the present invention, and the ink chamber 19 and the liquid reservoir 21 communicate with each other through a supply port 23. Further, the nozzle plate 11 is provided with a nozzle hole 25 for jetting the composition from the ink chamber 19 in a jet shape. On the other hand, the inkjet head 10
Is formed with an ink introduction hole 27 for supplying the composition to the liquid reservoir 21. A piezoelectric element 29 is joined to the surface of the vibration plate 13 opposite to the surface facing the ink chamber 19 so as to correspond to the position of the space 19.

The piezoelectric element 29 is located between the pair of electrodes 31. When energized, the piezoelectric element 29 bends so as to protrude outward, and at the same time, the diaphragm 1 to which the piezoelectric element 29 is joined.
3 also bends outward as a unit. Thereby, the volume of the ink chamber 19 increases. Therefore, the composition corresponding to the increased volume flows into the ink chamber 19 from the liquid reservoir 21 through the supply port 23.

Next, when the current supply to the piezoelectric element 29 is released, both the piezoelectric element 29 and the diaphragm 13 return to their original shapes. As a result, the space 19 also returns to its original volume, so that the pressure of the composition inside the ink chamber 19 increases, and the composition is ejected from the nozzle holes 25 toward the substrate.

The ink repellent layer 2 is provided around the nozzle hole 25 in order to prevent the composition from bending and clogging.
6 are provided. That is, as shown in FIG. 7, an ink-repellent layer 26 made of, for example, a Ni-tetrafluoroethylene eutectoid plating layer is provided around the nozzle hole 25.

Using such a head, for example, red,
By discharging the composition corresponding to green in a predetermined pattern, each organic light emitting layer can be provided to form a pixel.

In the method for producing an organic EL device of the present invention, the organic light emitting material composition used in the ink jet system may have the following characteristics.

The composition preferably has a contact angle of 30 ° to 170 ° with the material constituting the nozzle surface 33 of the nozzle provided on the ink jet head for discharging the composition, and 35 ° to 65 °. Is more preferred. When the composition has a contact angle in this range, flight bending of the composition can be suppressed, and precise patterning can be performed.

That is, if the contact angle is less than 30 degrees, the wettability of the composition to the constituent material of the nozzle surface increases, so that the composition adheres asymmetrically around the nozzle hole when the composition is discharged. May be. In this case, an attractive force acts between the composition adhering to the nozzle hole and the adhering substance to be ejected, so that the composition is ejected by a non-uniform force, so that a so-called flight bend cannot reach the target position. And the frequency of flight turns increases. Also, 170
Exceeding the degree, the interaction between the composition and the nozzle hole becomes extremely small, and the shape of the meniscus at the nozzle tip becomes unstable, so that it becomes difficult to control the discharge amount and discharge timing of the composition.

[0061] Here, the flight deflection means that when the composition is ejected from the nozzle, the position where the dot lands is shifted by 50 μm or more from the target position. The term "turning frequency" refers to the time until the above-described turning occurs when continuous ejection is performed at a frequency of 7200 Hz. Flying bends mainly occur when the nozzle holes have non-uniform wettability or due to clogging due to adhesion of solid components of the composition, and can be eliminated by cleaning the head. The higher the frequency of this flight bending, the more frequent head cleaning is required, and it can be said that the composition is a composition that reduces the efficiency of manufacturing an EL element by an ink jet method. At a practical level, it is necessary that the flight bend frequency be 1000 seconds or more. By preventing such flight bending, high-definition patterning is also possible and can be performed with high accuracy.

The viscosity of the composition is preferably from 1 cp to 20 cp, more preferably from 2 cp to 4 cp. When the viscosity of the composition is less than 1 cp, the content of the precursor and the fluorescent dye in the material becomes too small, and the formed light emitting layer cannot exhibit a sufficient coloring ability. on the other hand,
If it exceeds 20 cp, the composition cannot be discharged smoothly from the nozzle holes, and patterning becomes difficult unless the specifications of the apparatus are changed, such as increasing the diameter of the nozzle holes. Further, when the viscosity is large, solid components in the composition are easily precipitated, and the frequency of clogging of the nozzle holes increases.

The composition has a surface tension of 20 dyne /
cm to 70 dyne / cm, preferably 25 dyne / cm
-40 dyne / cm is more preferred. By setting the surface tension in this range, similarly to the case of the contact angle described above, the flight bend can be suppressed, and the frequency of the flight bend can be suppressed. When the surface tension is less than 20 dyne / cm, the wettability of the composition with respect to the constituent material of the nozzle surface increases, so that a flight bend occurs as in the case of the contact angle, and the frequency of the flight bend increases. On the other hand, if it exceeds 70 dyne / cm, the meniscus shape at the tip of the nozzle will not be stable, and it will be difficult to control the discharge amount and discharge timing of the composition.

The organic color-forming material composition suitable for the method for producing an organic EL device of the present invention is not limited as long as it satisfies at least one of the above-mentioned numerical ranges for the contact angle, viscosity and surface tension. Those satisfying the conditions for the characteristics of any combination of the above, and those satisfying all the characteristics are more preferable.

Example 2 FIG. 2 is a view showing a second example of the method for manufacturing an organic EL device according to the present invention.

In the present embodiment, pixel electrodes 101, 102, 103 and partition walls 105 are provided on a transparent base material 104 as in the first embodiment, and then a hole injection layer made of an organic compound or a positive electrode is formed by an ink jet method. The hole transport layer 120 was formed. The film thickness after heating at 200 ° C. in a nitrogen atmosphere for 2 hours was 50 nm.

The materials constituting the hole injection layer or the hole transport layer and the liquid composition are the same as those in the first embodiment, but are different from the first embodiment in that they are formed by an ink jet method.
By forming the hole injecting and transporting layer or the hole transporting layer in this way, an organic thin film can be formed with good controllability of the film thickness even with a high-definition pattern.

Further, a red light emitting layer 106 and a green light emitting layer 107 were provided by an ink jet method in the same manner as in Example 1, and a blue light emitting layer 108 was laminated thereon. Cathode 11
By forming No. 3, the organic EL device of the present invention could be obtained. The constituent materials and the forming method of the red light emitting layer 106, the green light emitting layer 107, the blue light emitting layer 108, and the cathode 113 are the same as those in the first embodiment.

(Embodiment 3) In this embodiment, an example in which a hole injection layer or a hole transport layer is formed on an anode, and then oxygen plasma is irradiated, and further, fluorocarbon gas plasma is irradiated. As a plasma generator, an apparatus that generates plasma in a vacuum or an apparatus that generates plasma at atmospheric pressure can be used in the same manner.

First, an organic film made of polyimide is formed between pixels. Next, Bayer Baytron P manufactured by Bayer is discharged onto the ITO electrode of the pixel portion by an ink-jet method to form a film.
It was baked at 0 ° C. for 1 hour. Next, oxygen plasma and CF4 plasma treatment are performed thereon, and the PPV precursor is dissolved in a solvent containing DMI as a main component on a green pixel among these pixels to form an ink. To form a discharge pattern. Next, on a pixel to be a red pixel, a PPV precursor mixed with rhodamine 1 is
The ink was dissolved in a solvent containing DMI as a main component to form an ink, and ejected by an inkjet method to form a pattern. 150 ° C
Then, a xylene solution of polydioctylfluorene was discharged and dried over the entire surface by an inkjet method.

On top of this, Ca was deposited in a thickness of 200 nm by vacuum heating evaporation, and Al was deposited in a thickness of 800 nm by sputtering to form a cathode. Finally, an electric wire was drawn out from the cathode, and sealing was performed on the cathode with a protective film made of an epoxy resin to complete an organic EL device.

Normally, the work function of ITO is about 4.8 eV, and the hole injection layer or the hole transport layer has a work function of 4.8 to 5.4 eV.
About V. By forming a fluoride layer thereon, the ionization potential on this surface was increased to about 5.7 eV. For this reason, the ionization potential was substantially the same as that of the light emitting material, the energy gap between the light emitting layer and the hole transport layer was reduced, and the hole injection was performed smoothly. As a result, an organic EL device having high energy efficiency could be provided.

Example 4 First, an organic film made of polyimide was formed between pixels, and then Bayer Baytron P manufactured by Bayer was discharged by spin coating onto the ITO electrode of the pixel portion to form a film. For 1 hour. Next, a PPV precursor was dissolved in a solvent containing DMI as a main component to form an ink on a pixel to be a green pixel, and the pattern was formed by discharging by an inkjet method. Next, on a pixel to be a red pixel, a PPV precursor mixed with rhodamine 1 was dissolved in a solvent containing DMI as a main component to form an ink, and the ink was ejected to form a pattern.

After heating in nitrogen at 200 ° C. for 2 hours for conjugation, a CF 4 plasma treatment was performed thereon. next,
A xylene solution of polydioctylfluorene was applied to the entire surface by spin coating, and dried. On top of this, lithium fluoride is laminated in a thickness of 20 nm by vacuum heating evaporation,
Further, Al was laminated to a thickness of 800 nm by a vacuum heating evaporation method to form a cathode. Finally, pull out the wire from the cathode,
Further, the cathode was sealed with a protective film made of an epoxy resin to complete an organic EL device.

Normally, the work function of ITO is about 4.8 eV, and the hole injection layer or the hole transport layer has a work function of 4.8 to 5.4 eV.
About V. The light emitting layer having the largest energy gap is a blue light emitting material. By forming a fluoride layer on the hole injection layer or the hole transport layer, the ionization potential on this surface was increased to about 5.7 eV. For this reason, the ionization potential was substantially the same as that of the blue light emitting material, the energy gap between the blue light emitting layer and the hole transport layer was reduced, and the hole injection was performed smoothly.

When a pattern is formed by the ink jet method, if the surface is fluorinated, there may be a case where a film cannot be formed uniformly with the ink. In this embodiment, the green pixel and the red pixel could be formed with a very good controllability. In addition, since the blue light emitting material was formed by spin coating, a uniform film could be formed on the entire surface.

As a result, an organic EL device having a high production yield and high energy efficiency could be provided.

(Embodiment 5) FIG. 3 is a view showing a fifth embodiment of the method of manufacturing an organic EL device according to the present invention.

In the present embodiment, pixel electrodes 101, 102, and 103 are patterned on a transparent substrate 104 in the same manner as in the first embodiment, and the organic compound is formed by spin coating without using a partition. Hole injection layer or hole transport layer 1
20 were formed. The film thickness after heating in a nitrogen atmosphere at 200 ° C. for 2 hours was 100 nm.

The material constituting the hole injection layer or the hole transport layer and the liquid composition are the same as those in Example 1, but the forming method is not limited thereto. For example, the ink jet method, dipping method, spin coating method, A casting method, a capillary method, a roll coating method, a bar coating method, or the like may be used.

Further, a red light-emitting layer 106 and a green light-emitting layer 107 were provided by an ink-jet method in the same manner as in Example 1, and a blue light-emitting layer 108 was laminated thereon. Cathode 11
By forming No. 3, the organic EL device of the present invention could be obtained. The constituent materials and the forming method of the red light emitting layer 106, the green light emitting layer 107, the blue light emitting layer 108, and the cathode 113 are the same as those in the first embodiment.

This embodiment is different from the above-described first embodiment in that a separation layer covering portions other than pixels is not provided. Since no separation layer is provided, the production efficiency is significantly improved. A display that does not require much definition can be manufactured sufficiently by this method, and is excellent in cost reduction and large area.

(Embodiment 6) FIG. 5 is a view showing an embodiment of the organic EL display device of the present invention.

In this embodiment, Al is placed on the glass substrate 104.
Bus lines (gate lines) 501 are provided by photolithography patterning, and thin film transistors (not shown) are formed thereon, and 101 (red), 102 (green), and 103
A (blue) ITO transparent pixel electrode was formed. After the partition 105 was provided, a hole injection layer or a hole transport layer 120 made of an organic compound was formed by spin coating. Light emitting layer 1
06 (red) and 107 (green) were formed by an inkjet method, and the blue light emitting layer 108 was formed by a spin coating method. Next, the cathode 113 was provided by a vacuum evaporation method, and the same organic EL element as in the first embodiment was manufactured.

Further, the protective substrate 502 is
4 so as to be fixed via a peripheral seal 503. Next, an inert gas 506 is introduced from the seal 504 into an inert gas atmosphere such as an argon gas, and finally the seal 504 is sealed with a sealant 505. By sealing and sealing the inert gas 506, the organic EL element can be protected from external contamination such as moisture and environmental changes, and the light emitting characteristics of the organic EL display device can be maintained. The sealing material 505 is preferably made of a material that does not transmit the inert gas 506.

When forming the cathode 113, the gate line 501
It was arranged to be able to contact with. Gate line 501
Has a role of controlling on / off of a TFT provided for each display pixel for selection of the display pixel on a row basis.
At the time of writing, the potential of the gate line 501 in one row is set to the selected level, and the TFT in this row is turned on. At this time, if the video signal voltage of the corresponding pixel is supplied from the source electrode wiring (not shown) of each column, the video signal voltage becomes TF
The charge reaching the pixel electrode through T and accumulating in the pixel up to the signal voltage level can be charged or discharged.

Since there is no need to pattern the cathode,
High definition was possible. In addition, each pixel obtained a luminance of 100 Cd / m ² or more even at a low voltage of 5 V or less. Since it is not a duty drive, it can be driven with low power consumption even with a large-screen organic EL display device having a diagonal size of 10 inches or more without being restricted by the number of pixels or the screen size.

Active matrix type organic EL of the present invention
In the above embodiment of the display device, a thin film transistor is used as a switching element. However, the present invention is not limited to this, and other types of switching elements, two-terminal elements, and switching elements such as MIM can be used. It is. Further, passive drive and static drive (still image, segment display) are also possible.

The number of switching elements per pixel is one.
The number of switching elements is not limited to one, and a plurality of switching elements may be provided in one pixel. FIG. 8 shows an example of an organic EL display device having a plurality of switching elements in one pixel. Here, the switching thin film transistor 142 transmits the potential of the signal electrode 132 to the current thin film transistor 143 according to the potential of the scan electrode 131, and the current thin film transistor 143 plays a role of controlling conduction between the common electrode 133 and the pixel electrode 141. I have.

Next, an example of a passive matrix (simple matrix) type organic EL display device using the organic EL element of the present invention will be described with reference to the drawings.

FIG. 9 is a schematic partial enlarged sectional view of the organic EL display device of the present invention. As shown in the figure, in the organic EL display device of the present embodiment, when manufacturing an organic EL element, a scanning electrode 53 and a signal electrode 54 formed in a strip shape are orthogonal to each other via an organic EL element 52. It is arranged to be.

In such passive matrix driving, the scanning electrodes 53 are sequentially selected in a pulsed manner, and when the scanning electrodes 53 are selected, the signal electrodes 54 corresponding to the respective pixels are selected.
And applying a voltage. Such selection is controlled by the controller 55.

In the case of the passive drive type, it is necessary that the cathode (cathode) is patterned and separated for each line. The cathode is patterned by, for example, a mask evaporation method or a laser cutting method.

FIG. 10 shows the scanning electrodes 13 and the signal electrodes 14.
1 shows an example of a driving waveform of a voltage applied to the. In the driving waveform shown in the drawing, a voltage Vs sufficient to emit light is applied to the selected pixel. Further, the display density of the pixel is controlled by a waveform having a pulse width corresponding to the gradation to be displayed. On the other hand, a voltage Vn that is equal to or lower than the light emission threshold voltage
Is applied.

In FIG. 10, Tf indicates one operation time. Here, the case of driving at a duty ratio of 1/100 will be described. It was driving the organic EL display device having the organic EL device of Example 2 with the condition, the white light emission of all the lights, 100 Cd at a driving voltage of 20V ^{/ m} 2 0
0. Met.

[0096]

As described above, according to the present invention, all organic layers can be formed by a coating method, in particular, an ink-jet method, a production method capable of increasing the productivity and increasing the screen size, and having a higher color purity than the conventional method. A high-definition, high-definition organic EL display device can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method for manufacturing an organic EL device of the present invention.

FIG. 2 is a cross-sectional view illustrating a method for manufacturing an organic EL device of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing an organic EL device of the present invention.

FIG. 4 is a simple sectional view of the organic EL display device of the present invention.

FIG. 5 is a simple sectional view of the organic EL display device of the present invention.

FIG. 6 is a plan perspective view showing a configuration example of an ink jet printer head used for manufacturing the organic EL element of the present invention.

FIG. 7 is a sectional view of a nozzle portion of an ink jet printer head used for manufacturing the organic EL element of the present invention.

FIG. 8 is a diagram showing a part of the organic EL display device of the present invention.

FIG. 9 is a perspective view showing an outline of an organic EL display device of the present invention.

FIG. 10 is a diagram showing an example of a drive waveform of a voltage applied to an electrode of the organic EL display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Ink-jet head 11 ... Nozzle plate 13 ... Vibrating plate 15 ... Partition member 19 ... Ink chamber 21 ... Liquid pool 23 ... Supply port 25 ... Nozzle hole 26 ... Ink repellent layer 27 ... Ink introduction hole 29 ... Piezoelectric element 31 ... Electrode 33 ... Nozzle surface 52 ... Organic EL element 53 ... Scan electrode 54 ... Signal electrode 55 ... Controller 101 ... Pixel electrode (red) 102 ... Pixel electrode (green) 103 ... Pixel electrode (blue) 104 ... Transparent substrate 105 ... Partition 106 ... Light-emitting layer (red) 107 Light-emitting layer (green) 108 Light-emitting layer (blue) 109 Ink-jet printing apparatus 110 Ink-jet head 113 Cathode 131 Scan electrode 132 Signal electrode 133 Common electrode 141 Pixel electrode 142 Switching TFT 143: current TFT 120: hole injection layer or hole transport layer 401 Protective film 501 ... bus lines 502 ... protective substrate 503 ... sealing 504 ... sealing 505 ... Fuanazai 506 ... inert gas

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kiguchi 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Hidekazu Kobayashi 3-3-5, Yamato, Suwa-shi, Nagano Seiko-Epson F term in the company (reference) 3K007 AB03 AB04 AB18 CA01 CB01 DA01 DB03 EB00 FA01

Claims (13)

[Claims] In a method of manufacturing an organic EL device having a structure in which a hole injection layer or a hole transport layer and a light emitting layer are sandwiched between an anode and a cathode, a step of forming a pixel electrode acting as an anode on a transparent substrate. And a step of forming a hole injection layer or a hole transport layer made of an organic compound, a step of patterning a red light emitting layer made of an organic compound, a green light emitting layer by an inkjet method, and a blue light emitting layer made of an organic compound. A method for producing an organic EL device, comprising: a step of forming by a coating method; and a step of forming a cathode. 2. The method for manufacturing an organic EL device according to claim 1, wherein a separation film for covering other than pixels is provided on the substrate. 3. A film containing at least a polythiophene derivative and a silane coupling agent is formed by a coating method.
3. The method for manufacturing an organic EL device according to claim 1, wherein the hole injection layer or the hole transport layer is formed by thermosetting. 4. A method according to claim 1, wherein a liquid containing at least a polythiophene derivative and a silane coupling agent is formed on the anode of the pixel portion by an ink-jet method and thermally cured to form the hole injection layer or the hole transport layer. 3. The method for manufacturing an organic EL device according to claim 1, wherein: 5. A liquid containing at least a precursor of polyparaphenylene and a derivative thereof is formed into a film by an ink jet method, and is heated and conjugated to form the red and green light emitting layers. Item 5. The method for producing an organic EL device according to any one of Items 1 to 4. 6. The method according to claim 1, wherein the blue light emitting layer is formed by applying a liquid in which at least a polyfluorene derivative is dissolved and drying the liquid. 7. After forming a hole injection layer or a hole transport layer on the anode, irradiate a plasma of a fluorocarbon gas,
7. The method for manufacturing an organic EL device according to claim 1, wherein a light emitting layer is formed thereafter. 8. A method of forming a hole injection layer or a hole transport layer on an anode, forming a red or green light emitting layer, irradiating a plasma of fluorocarbon gas, and thereafter forming the light emitting layer. The organic E according to any one of claims 1 to 6,
Manufacturing method of L element. 9. The method according to claim 7, wherein said fluorocarbon gas is CF4. 10. The method of manufacturing an organic EL device according to claim 7, wherein oxygen plasma is applied before the plasma of the fluorocarbon gas is applied. 11. An organic EL display device comprising an organic EL element produced by the method according to claim 1. 12. The organic EL display device according to claim 11, wherein a TFT element for driving each pixel is formed on said transparent substrate. 13. The organic EL display device according to claim 11, wherein a protective film is formed on the cathode.