WO2013168546A1 - Process for producing display device - Google Patents

Abstract

A process for producing a display device is provided in which a thin organic film layer can be formed in an even thickness without requiring an oxygen plasma treatment, etc. The process is a process for producing a display device which comprises a supporting substrate, partition walls, and a plurality of organic EL elements and in which the organic EL elements each comprises a first electrode, a thin organic film layer, and a second electrode in this order from the supporting substrate side, the process comprising: a step in which a supporting substrate is prepared on which partition walls pattern-wise formed by photolithography from a photosensitive resin composition containing a liquid repellent and a first electrode have been disposed; a step in which the surface of the first electrode is cleaned with a solution containing at least any one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride or with a developing solution for the photosensitive resin composition; a step in which a thin organic film layer is formed on the first electrode through coating fluid application; and a step in which a second electrode is formed on the thin organic film layer.

Description

Manufacturing method of display device

The present invention relates to a method for manufacturing a display device.

As one of display devices, there is a display device using an organic electroluminescence element (hereinafter sometimes referred to as “organic EL element”) as a light source of a pixel. As a configuration of the organic EL element used for this pixel, there is one adopting a microcavity structure (microresonator structure) (for example, see Patent Document 1). By adopting such a configuration, it is possible to improve the color purity and increase the luminance within a predetermined viewing angle range.

JP 2002-367770 A

In the above-described display device, a large number of organic EL elements corresponding to pixels are arranged on a predetermined support substrate. A partition wall for defining a predetermined partition is provided on the support substrate, and a large number of organic EL elements are arranged in alignment with regions partitioned by the partition wall.

Each organic EL element is formed by laminating a first electrode, an organic thin film layer, and a second electrode in this order from the support substrate side.

The organic thin film layer of the organic EL element can be formed by, for example, a coating method. Hereinafter, a method for forming the organic thin film layer will be described with reference to FIG. As shown in FIG. 13A, first, a support substrate 12 on which a first electrode 16 and a partition wall 13 are formed in advance is prepared. Next, an ink 17 containing a material to be the organic thin film layer 18 is supplied to a region (concave portion) 15 surrounded by the partition wall 13 in the support substrate 12. The supplied ink 17 is accommodated in a region 15 surrounded by the partition wall 13 (see FIG. 13B). Subsequently, the organic thin film layer 18 is formed by the evaporation of the solvent of the ink 17 (see FIG. 13C).

If the partition wall 13 is lyophilic with respect to the ink 17, the ink supplied to the specific recess 15 may flow to the adjacent recess 15 through the partition wall 13 surface. In order to prevent such ink from flowing out, it is necessary to impart a certain degree of liquid repellency to the partition wall 13.

For this purpose, for example, after the partition walls are formed, the partition walls may be subjected to plasma treatment with a fluorine-based gas to impart liquid repellency to the partition walls. However, in this method, the organic thin film layer is contaminated by the reaction product of the fluorine-based gas, and the characteristics of the organic EL element are deteriorated.

Therefore, there is a case in which a partition wall is formed using a photosensitive resin composition containing a liquid repellent agent, thereby giving a liquid repellency to the partition wall without performing a plasma treatment with a fluorine-based gas.

When the organic thin film layer is formed by the above-described method using such a partition wall, there is a problem that an organic thin film layer having a uniform film thickness cannot be formed.

If an organic thin film layer with a non-uniform film thickness is formed, current concentrates on the thin film region and uniform light emission cannot be obtained. Further, in the above-described microcavity structure, the thickness of each organic thin film layer is set in accordance with the emission wavelength, but there is a problem that an organic thin film layer having an intended thickness cannot be obtained and desired characteristics cannot be obtained. . In the microcavity structure, since the film thickness of the organic thin film layer greatly affects the characteristics of the element, improvement of the in-plane uniformity of the film thickness is particularly required.

Note that the in-plane uniformity of the film thickness of the organic thin film layer is considered to be due to unevenness in wettability on the first electrode. For example, if a portion having poor wettability is locally present on the first electrode, the film is thinned while ink is being repelled at that portion, so that the in-plane uniformity of the film thickness decreases. Therefore, it is conceivable to perform a treatment for improving the wettability of the first electrode before applying the ink. For example, the wettability of the first electrode can be enhanced by oxygen plasma treatment. When ink is supplied after increasing the wettability of the first electrode in this way, the ink wets and spreads on the first electrode, and an organic thin film layer having a uniform film thickness is obtained. However, when the oxygen plasma treatment is performed, the surface of the partition wall is etched, the thickness of the partition wall varies, and the liquid repellency of the partition wall decreases. If it does so, the ink supplied in the recessed part (area | region divided by the partition) may overflow, and there exists a problem that an organic EL element cannot be formed as designed.

Therefore, an object of the present invention is to provide a manufacturing method of a display device capable of forming an organic thin film layer with a uniform film thickness without performing oxygen plasma treatment or the like.

The present invention includes a support substrate, partition walls that define predetermined sections on the support substrate, and a plurality of organic EL elements that are respectively provided in sections defined by the partition walls. Is a method of manufacturing a display device including the first electrode, the organic thin film layer, and the second electrode in this order from the support substrate side,
Using a photosensitive resin composition containing a liquid repellent, a step of preparing a support substrate on which a partition wall formed by patterning by a photolithography method and a first electrode are provided;
Cleaning the surface of the first electrode with a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition;
Forming an organic thin film layer on the first electrode by a coating method;
And a step of forming a second electrode on the organic thin film layer.
In each organic EL element, the first electrode may be a single layer or two or more layers, the organic thin film layer may be a single layer or two or more layers, and the second electrode may be a single layer. There may be two or more layers.

According to the present invention, instead of performing oxygen plasma treatment or the like, a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid and hydrogen chloride, or a photosensitive resin composition used for forming a partition wall is provided. By washing the surface of the first electrode with the developer, the wettability of the surface of the first electrode can be enhanced and the wettability can be made uniform over the entire surface of the first electrode. Thereby, the organic thin film layer can be formed with a uniform film thickness without performing oxygen plasma treatment or the like.

FIG. 1 is a diagram schematically showing an enlarged part of a display device 1 according to an embodiment of the present invention. FIG. 2 is an enlarged plan view schematically showing a part of the display device 1 according to the embodiment of the present invention. FIG. 3A is a view for explaining a method for manufacturing a display device according to an embodiment of the present invention. FIG. 3B is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 3C is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 4A is a view for explaining a method for manufacturing a display device according to an embodiment of the present invention. FIG. 4B is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 4C is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 5A is a diagram for explaining a method for manufacturing a display device according to an embodiment of the present invention. FIG. 5B is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 5C is a view for explaining the method for manufacturing the display device according to the embodiment of the present invention. FIG. 6 is a plan view schematically showing an enlarged part of the display device 1 according to an embodiment of the present invention. FIG. 7 is a diagram schematically showing an enlarged part of the display device 1 according to an embodiment of the present invention. FIG. 8 is a diagram showing a PL spectrum of the luminescent material used in the calculation of FIG. FIG. 9 is a diagram illustrating the film thickness dependence of the hole injection layer of the EL spectrum in the microcavity structure. FIG. 10 is a diagram for comparing the EL spectrum of the organic EL element produced by the production method of the present invention and the PL spectrum of the light emitting material. FIG. 11 is a diagram for comparing the EL spectrum of the organic EL element produced by the production method of the present invention and the PL spectrum of the light emitting material. FIG. 12 is a diagram for comparing the EL spectrum of the organic EL element produced by the production method of the present invention and the PL spectrum of the light emitting material. FIG. 13A is a diagram for explaining a method for manufacturing the display device. FIG. 13B is a diagram for explaining a method for manufacturing the display device. FIG. 13C is a diagram for explaining a method for manufacturing the display device.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. For ease of understanding, the scale of each member in the drawings may be different from the actual scale. In the display device, there are members such as lead wires of electrodes, but the description thereof is omitted because it is not necessary to explain the present invention. For convenience of explanation of the layer structure and the like, in the example shown below, the explanation will be made with the figure in which the support substrate is arranged below. However, the display device of the present invention is not necessarily arranged in the vertical and horizontal directions and is manufactured or used. It is not necessarily limited to the form in which etc. are made, You may adjust suitably.

The present invention includes a support substrate, partition walls that define predetermined sections on the support substrate, and a plurality of organic EL elements that are respectively provided in sections defined by the partition walls. Is a method of manufacturing a display device including a first electrode, an organic thin film layer, and a second electrode in this order from the support substrate side, and pattern formation is performed by a photolithography method using a photosensitive resin composition containing a liquid repellent. A step of preparing a support substrate provided thereon with a partition wall formed by the first electrode, and a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, Or a step of cleaning the surface of the first electrode with a developer of the photosensitive resin composition, a step of forming an organic thin film layer on the first electrode by a coating method, and a step of forming a first layer on the organic thin film layer. And forming an electrode, a method of manufacturing a display device.

Display devices mainly include active matrix drive type devices and passive matrix drive type devices. Although the present invention can be applied to both types of display devices, in this embodiment, a display device applied to an active matrix drive type display device will be described as an example.

<Configuration of display device>
First, the configuration of the display device will be described. FIG. 1 is a diagram schematically showing an enlarged part of the display device 1 of the present embodiment. FIG. 2 is a plan view schematically showing an enlarged part of the display device 1 of the present embodiment. The display device 1 mainly includes a support substrate 2, partition walls 3 that define predetermined sections on the support substrate 2, and a plurality of organic EL elements 4 that are provided in the sections defined by the partition walls 3. Including.

The partition wall 3 is formed on the support substrate 2 in a lattice shape or a stripe shape, for example. FIG. 2 shows a display device 1 provided with a grid-like partition wall 3 as one embodiment. In FIG. 2, the hatched area corresponds to the partition wall 3.

A plurality of recesses 5 defined by the partition walls 3 and the support substrate 2 are set on the support substrate 2. The concave portion 5 corresponds to a section defined by the partition wall 3.

The partition wall 3 of this embodiment is provided in a lattice shape. Therefore, when viewed from one side in the thickness direction Z of the support substrate 2 (hereinafter sometimes referred to as “in plan view”), the plurality of recesses 5 are arranged in a matrix. That is, the recesses 5 are provided with a predetermined interval in the row direction X and aligned in the column direction Y with a predetermined interval. The shape of each recess 5 in plan view is not particularly limited. For example, the recess 5 may be formed in a shape such as a substantially rectangular shape, a substantially oval shape, or an oval shape in plan view. In the present embodiment, a substantially rectangular recess 5 is provided in plan view. In the present specification, the row direction X and the column direction Y are directions perpendicular to the thickness direction Z of the support substrate 2 and perpendicular to each other.

The partition wall 3 of this embodiment has a so-called forward taper shape. That is, the partition wall 3 of this embodiment is formed in a tapered shape as it is separated from the support substrate 2. For example, when the partition wall extending in the column direction Y is cut along a plane perpendicular to the extending direction (column direction Y), the cross-sectional shape is formed to be tapered as the distance from the support substrate increases. In FIG. 1, a substantially isosceles trapezoidal partition wall is shown. When the upper base and the lower base on the support substrate side are compared, the lower base is wider than the upper base. The section of the partition wall actually formed does not necessarily have a trapezoidal shape, and the straight part and corners of the trapezoidal shape may be rounded and may be formed in a so-called kamaboko shape (dome shape).

In the present embodiment, the partition wall 3 is mainly provided in a region excluding a region where the organic EL element is provided. The partition 3 is mainly provided in a region excluding a region where the first electrode 6 described later is provided, but the end 3 a is also formed on the peripheral portion of the first electrode 6 so as to overlap the first electrode 6. It is formed. Note that the end 3 a of the partition wall 3 does not need to be formed so as to cover all the peripheral edges of the first electrode 6. For example, when the stripe-shaped partition wall 3 to be described later is formed, the partition wall may be formed so that the opposite ends of the four sides of the first electrode 6 are covered by the end portions of the partition wall. In the present embodiment, the end 3 a of the partition wall 3 is formed so as to cover all the peripheral edges of the first electrode 6.

As still another embodiment, an insulating film having an opening on the first electrode may be further provided between the partition wall and the support substrate.

The organic EL element 4 is provided in a section defined by the partition 3 (that is, the recess 5). When the grid-like partition 3 is provided as in the present embodiment, each organic EL element 4 is provided in each recess 5. Therefore, the organic EL elements 4 are arranged in a matrix like the respective recesses 5 and are arranged on the support substrate 2 with a predetermined interval in the row direction X and with a predetermined interval in the column direction Y. Is provided.

In the present embodiment, three types of organic EL elements 4 are provided. That is, (1) a red organic EL element 4R that emits red light, (2) a green organic EL element 4G that emits green light, and (3) a blue organic EL element 4B that emits blue light are provided. These three types of organic EL elements 4R, 4G, and 4B are arranged in an aligned manner by, for example, repeating the following rows (I), (II), and (III) in the column direction Y in this order. (See FIG. 2).
(I) Rows in which the red organic EL elements 4R are arranged at predetermined intervals in the row direction X.
(II) Rows in which the green organic EL elements 4G are arranged at predetermined intervals in the row direction X.
(III) A row in which the blue organic EL elements 4B are arranged at predetermined intervals in the row direction X.

As another embodiment, in addition to the above three types of organic EL elements, for example, an organic EL element that emits white light may be further provided. In addition, a monochrome display device may be realized by providing only one type of organic EL element.

The organic EL element 4 is configured by laminating a first electrode, an organic thin film layer, and a second electrode in this order from the support substrate 2 side. In the present specification, of the layers provided between the first electrode 6 and the second electrode 10, a layer containing an organic substance is referred to as an organic thin film layer. The organic EL element 4 includes at least one light emitting layer as an organic thin film layer. In addition to the one light emitting layer, the organic EL element may further include an organic thin film layer or an inorganic layer different from the light emitting layer as necessary. For example, a hole injection layer, a hole transport layer, an electron block layer, an electron transport layer, an electron injection layer, and the like may be provided between the first electrode 6 and the second electrode 10. Two or more light emitting layers may be provided between the first electrode 6 and the second electrode 10. In the organic EL element 4, the first electrode may be a single layer or two or more layers, the organic thin film layer may be a single layer or two or more layers, and the second electrode is a single layer. Also, two or more layers may be used.

The organic EL element 4 includes a first electrode 6 and a second electrode 10 as a pair of electrodes including an anode and a cathode. One of the first electrode 6 and the second electrode 10 is provided as an anode, and the other electrode is provided as a cathode.

In this embodiment, as an example, the first electrode 6 functioning as an anode, the first organic thin film layer 7 functioning as a hole injection layer, the second organic thin film layer 9 functioning as a light emitting layer, and the second functioning as a cathode. The organic EL element 4 configured by laminating the electrodes 10 on the support substrate 2 in this order will be described.

In this embodiment, three types of organic EL elements are provided, but these have different configurations of the second organic thin film layer (light emitting layer in this embodiment) 9. The red organic EL element 4R includes a red light emitting layer 9 that emits red light. The green organic EL element 4G includes a green light emitting layer 9 that emits green light. The blue organic EL element 4B includes a blue light emitting layer 9 that emits blue light.

In the present embodiment, the first electrode 6 is provided for each organic EL element 4. That is, the same number of first electrodes 6 as the organic EL elements 4 are provided on the support substrate 2. The first electrodes 6 are provided corresponding to the arrangement of the organic EL elements 4 and are arranged in a matrix like the organic EL elements 4. The partition wall 3 of the present embodiment is formed in a lattice shape mainly in a region excluding the first electrode 6, but is further formed so that the end 3 a covers the peripheral edge of the first electrode 6 (see FIG. 1).

The first organic thin film layer 7 functioning as a hole injection layer is provided on the first electrode 6 in the recess 5. The first organic thin film layer 7 is provided with a different material or film thickness for each type of organic EL element, if necessary. In addition, from a viewpoint of the simplicity of the formation process of the 1st organic thin film layer 7, you may form all the 1st organic thin film layers 7 with the same material and the same film thickness. Furthermore, when forming an organic EL element having a microcavity structure as will be described later, the film thickness of the first organic thin film layer 7 is different for each type of organic EL element so that optical resonance occurs in accordance with the emission wavelength. You may adjust.

The second organic thin film layer 9 functioning as a light emitting layer is provided on the first organic thin film layer 7 in the recess 5. As described above, the light emitting layer is provided according to the type of the organic EL element. Therefore, the red light emitting layer 9 is provided in the recess 5 in which the red organic EL element 4R is provided. The green light emitting layer 9 is provided in the recess 5 in which the green organic EL element 4G is provided. The blue light emitting layer 9 is provided in the recess 5 in which the blue organic EL element 4B is provided.

The second electrode is provided on the organic thin film layer, but in this specification, being provided on the layer “upper” may take a form of being in contact with the lower layer and a form of being provided apart from the lower layer. For example, a predetermined inorganic layer may be provided between the organic thin film layer and the second electrode provided thereon.

In the present embodiment, the second electrode 10 is formed on the entire surface in the display area where the organic EL element 4 is provided. That is, the second electrode 10 is formed not only on the second organic thin film layer 9 but also on the partition 3, continuously formed over a plurality of organic EL elements, and as a common electrode for all the organic EL elements 4. Provided.

<Manufacturing method of display device>
Hereinafter, a manufacturing method of the display device will be described with reference to FIGS.

(Process to prepare support substrate)
In this step, a support substrate is prepared in which a partition formed by patterning by a photolithography method using a photosensitive resin composition containing a liquid repellent and a first electrode are provided thereon. That is, in this step, a support substrate in which a liquid repellent partition and a first electrode are provided is prepared. In this step, a support substrate on which the partition wall and the first electrode are provided in advance may be prepared. In this step, the partition wall and / or the first electrode is formed so that the partition wall and the first electrode are formed. A provided support substrate may be prepared. Note that in the case of an active matrix display device, a substrate on which circuits for individually driving a plurality of organic EL elements are formed in advance may be used as the support substrate 2. For example, a substrate on which a TFT (Thin Film Transistor), a capacitor, and the like are formed in advance may be used as the support substrate.

In this embodiment, first, a plurality of first electrodes 6 are formed in a matrix on the support substrate 2 (see FIG. 3A). For example, the first electrode 6 may be patterned by forming a conductive thin film on one surface of the support substrate 2 and patterning it in a matrix by a photolithography method. Further, for example, a mask having an opening formed in a predetermined portion is disposed on the support substrate 2, and a conductive material is selectively deposited on the predetermined portion on the support substrate 2 through the mask, thereby the first electrode 6. The pattern may be formed. The material of the first electrode 6 will be described later.

Next, in this step, a pattern is formed by a photolithographic method using a photosensitive resin composition containing a liquid repellent agent, so that the partition wall is patterned so that the end thereof is in contact with the first electrode. In this embodiment, first, a photosensitive resin composition containing a liquid repellent is applied onto the support substrate 2 to form a partition wall forming film 8. Examples of the method for applying the photosensitive resin composition include spin coating and slit coating.

After the photosensitive resin composition is applied and formed on the support substrate, it is usually pre-baked. For example, pre-baking is performed by heating the support substrate 2 at a temperature of 80 ° C. to 110 ° C. for 60 seconds to 180 seconds to remove the solvent of the photosensitive resin composition (see FIG. 3B).

Next, a photomask 21 that shields light of a predetermined pattern is disposed on the support substrate 2, and the partition wall forming film 8 is exposed through the photomask 21. The photosensitive resin composition includes positive and negative photosensitive resin compositions, but any photosensitive resin composition may be used in this step. When a positive photosensitive resin composition is used, light is irradiated to the remaining part of the partition forming film 8 except the part where the partition 3 is to be formed. In the case where a negative photosensitive resin composition is used, light is irradiated on the part of the partition forming film 8 where the partition 3 is to be formed. In this step, a case where a negative photosensitive resin composition is used will be described with reference to FIG. 3C. As shown in FIG. 3C, a photomask 21 is arranged on the substrate on which the partition wall forming film 8 is formed, and light is irradiated through the photomask 21, whereby the partition wall forming film 8 mainly includes the partition wall. 3 is irradiated with light. In FIG. 3C, the light applied to the partition wall forming film 8 is schematically indicated by an arrow symbol.

Next, the exposed partition wall forming film 8 is developed using a developer described later. Thereby, the partition 3 is patterned (see FIG. 4A). After development, post bake. For example, post-baking is performed by heating the substrate at a temperature of 200 ° C. to 230 ° C. for 15 to 60 minutes to cure the partition walls 3.

Thus, by using the photosensitive resin composition containing the liquid repellent and patterning the barrier ribs by photolithography, the barrier ribs having liquid repellency can be obtained. The contact angle of the partition walls used in this embodiment is preferably 25 ° to 60 °, more preferably 30 ° to 45 °, for example, with respect to anisole.

As described above, the photosensitive resin composition used for forming the partition includes a negative type and a positive type.
(Negative photosensitive resin composition)
In the negative photosensitive resin composition, the portion irradiated with light is insolubilized in the developer and remains.

In general, a binder resin, a crosslinking agent, a photoreaction initiator, a solvent, and other additives are blended in the photosensitive resin composition.

The binder resin is polymerized in advance. Examples thereof include a non-polymerizable binder resin that does not have self-polymerizability and a polymerizable binder resin into which a substituent having polymerizability is introduced. The binder resin has a weight average molecular weight in the range of 5,000 to 400,000 determined by gel permeation chromatography (GPC) using polystyrene as a standard.

Examples of the binder resin include phenol resin, novolac resin, melamine resin, acrylic resin, epoxy resin, and polyester resin. As the binder resin, either a homopolymer or a copolymer obtained by combining two or more monomers may be used. The binder resin is generally 5% to 90% by mass fraction with respect to the total solid content of the photosensitive resin composition.

The crosslinking agent is a compound that can be polymerized by an active radical generated from a photopolymerization initiator by irradiation of light, an acid, or the like, and examples thereof include a compound having a polymerizable carbon-carbon unsaturated bond. The crosslinking agent may be a monofunctional compound having one polymerizable carbon-carbon unsaturated bond in the molecule, or a bifunctional or trifunctional compound having two or more polymerizable carbon-carbon unsaturated bonds. The above polyfunctional compounds may be used. In the said photosensitive resin composition, a crosslinking agent is 0.1 to 70 mass parts normally, when the total amount of binder resin and a crosslinking agent is 100 mass parts. Moreover, in the said photosensitive resin composition, a photoinitiator is 1 mass part or more and 30 mass parts or less normally, when the total amount of binder resin and a crosslinking agent is 100 mass parts.

(Positive photosensitive resin composition)
On the other hand, in the positive photosensitive resin composition, the irradiated portion is solubilized in the developer. A positive photosensitive resin composition is generally constituted by combining a resin and a compound that becomes hydrophilic by a photoreaction.

As a positive photosensitive resin composition, a combination of a resin having chemical resistance and adhesion such as novolac resin, polyhydroxystyrene, acrylic resin, methacrylic resin, polyimide, and a photodegradable compound is used. You can do it.

(Liquid repellent)
Examples of the liquid repellent contained in the positive or negative photosensitive resin composition include a fluorine-containing compound and a silicone-containing compound, and fluorine exhibiting excellent liquid repellency with respect to an organic solvent. Containing compounds are preferred.

Examples of the fluorination-containing compound include compounds having a linear or branched fluoroalkyl group and / or fluoropolyether group having 1 to 8 carbon atoms. The fluorine-containing compound is preferably a polymer having a crosslinkable group, and more preferably a polymer having a fluoroalkyl group and / or fluoropolyether group having 4 to 6 carbon atoms and having a crosslinkable group. Alternatively, the fluorine-containing compound preferably has a soluble function in the developer. The fluorine-containing compound is not limited to a polymer and may be a low molecular compound as long as it can impart liquid repellency to the partition wall surface after the partition wall is formed.

The above crosslinkable group imparts a crosslinkable function to the fluorine-containing compound, and examples thereof include an ethylenically unsaturated bond group, an epoxy group, and a hydroxyl group. The type of the crosslinkable group is not limited to the above as long as it has a function of crosslinking with the photosensitive resin used for forming the partition wall.

Specific examples of the liquid repellent include Mega-Fac RS-101, RS-102, RS-105, RS-401, RS-402, RS-501, RS-502, RS-718 (manufactured by DIC), OPTOOL DAC , Optoace HP series (manufactured by Daikin Industries, Ltd.), perfluoro (meth) acrylate, perfluorodi (meth) acrylate, and the like.

The above liquid repellents may be used alone or in combination of two or more. The liquid repellent is usually 0.1 parts by mass or more and 3 parts by mass or less in terms of mass fraction with respect to the total solid content excluding the liquid repellent of the photosensitive resin composition.

(Developer)
Examples of the developer used for development include an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, and an aqueous tetramethylammonium hydroxide (TMAH) solution.

The shape of the partition 3 and the arrangement thereof are appropriately set according to the specifications of the display device such as the number of pixels and the resolution, the ease of manufacturing, and the like. For example, the width of the partition wall 3 in the row direction X or the column direction Y is about 5 μm to 50 μm, the height of the partition wall 3 is about 0.5 μm to 5 μm, and the partition walls 3 adjacent to each other in the row direction X or the column direction Y , That is, the width of the recess 5 in the row direction X or the column direction Y is about 10 μm to 500 μm. The width of the first electrode 6 in the row direction X or the column direction Y is about 10 μm to 500 μm, respectively.

(Step of cleaning the surface of the first electrode)
In this step, the surface of the first electrode is cleaned (see FIGS. 4A and 4B).

As shown in FIG. 4A, the partition wall forming film 8 formed on the first electrode 6 remains with the residue 19 adhering to the first electrode 6 even when the developing process is performed using the developer. Sometimes. In this step, the surface of the first electrode 6 is cleaned to remove the residue 19 and dirt of the partition wall forming film 8 and clean the surface of the first electrode 6. As a result, the wettability of the surface of the first electrode 6 can be improved and the wettability can be made uniform over the entire surface of the first electrode 6.

In this step, the surface of the first electrode is washed with a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition.

As the developer used for washing in this step, a developer that can be used for forming the partition walls by photolithography can be used. For example, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide (TMAH) aqueous solution can be used. By using such a developer, the residue 19 of the partition wall forming film 8 can be efficiently removed. The developer used in this step may be a developer having the same composition as the developer used for forming the partition walls, or a developer having a different composition may be used. When developers having different compositions are used, the remaining residues that cannot be removed in the development step can be more efficiently removed.

Note that the concentration of the developer used in this step is preferably lower than the concentration of the developer used for forming the partition walls. For example, assuming that the concentration of the developer used for forming the partition wall is A (% by weight) and the concentration of the developer used in this step is B (% by weight), “A / B” is 1 to 25. 2 to 5 are more preferable. By cleaning the first electrode at such a concentration, the partition walls can be prevented from being etched.

Examples of the solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid and hydrogen chloride used for washing in this step include a mixed solution of hydrochloric acid and ferric chloride solution, a mixed solution of hydrochloric acid and nitric acid, and phosphoric acid. Examples thereof include a mixed solution of nitric acid, nitric acid and acetic acid, and an oxalic acid aqueous solution.

Such a solution is appropriately selected according to the type of the first electrode. For example, when the first electrode is composed of an ITO (Indium Tin Oxide) thin film, cleaning is performed using a mixed solution of hydrochloric acid and ferric chloride solution, a mixed solution of hydrochloric acid and nitric acid, or a mixed solution of phosphoric acid, acetic acid and nitric acid. Of these, washing with a mixed solution of phosphoric acid, acetic acid and nitric acid is more preferred. For example, in the case where the first electrode is formed of an IZO (Indium Zinc Oxide) thin film, it is preferable to perform cleaning using a mixed solution of phosphoric acid, acetic acid and nitric acid, or an oxalic acid aqueous solution.

When the first electrode made of ITO is washed with a mixed solution of hydrochloric acid and ferric chloride solution, a mixed solution having a concentration of 5 to 25% by weight of hydrochloric acid and 10 to 30% by weight of ferric chloride is preferable. More preferred is a mixed solution having a concentration of 17.5% by weight hydrochloric acid and 20% by weight ferric chloride. Further, when the first electrode made of ITO is cleaned using a mixed solution of phosphoric acid, acetic acid and nitric acid, 60 to 80% by weight of phosphoric acid, 0.1 to 20% by weight of acetic acid, and 0.1 to 10% by weight of nitric acid. A mixed solution having a concentration is preferable, and a mixed solution having a concentration of 71 wt% phosphoric acid, 10.5 wt% acetic acid, and 2.2 wt% nitric acid is more preferable.

When the first electrode made of IZO is washed with a mixed solution of phosphoric acid, acetic acid and nitric acid, phosphoric acid 0.1 to 20% by weight, acetic acid 0.1 to 10% by weight, nitric acid 0.1 to 10% by weight A mixed solution having a concentration of 0.1% by weight of phosphoric acid, 1.1% by weight of acetic acid, and 0.2% by weight of nitric acid is more preferable.

Further, when the first electrode made of IZO is washed with an oxalic acid aqueous solution, the concentration is preferably 1 to 10% by weight.

When the surface of the first electrode is washed with a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, the residue 19 and dirt on the partition wall forming film 8 are removed. Depending on the case, the surface of the first electrode 6 is etched. As a result, the wettability of the surface of the first electrode 6 can be improved and the wettability can be made uniform over the entire surface of the first electrode 6.

By washing the surface of the first electrode as described above, the surface of each first electrode 6 is made uniformly lyophilic. In the cleaning, the surface of the first electrode is contacted with a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid and hydrogen chloride, or a developer of the photosensitive resin composition used for forming the partition walls. As long as it can be made, the method is not particularly limited. For example, in the cleaning, the surface of the first electrode is immersed in a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition used to form the partition walls. You may carry out by doing. Alternatively, in the cleaning, a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition used for forming the partition walls is formed on the surface of the first electrode. You may implement by apply | coating. Alternatively, in the cleaning, a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition used for forming the partition walls is formed on the surface of the first electrode. It may be carried out by spraying with a shower.

After washing the surface of the first electrode, washing with water supports a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid and hydrogen chloride, or a developer of the photosensitive resin composition It can be removed from the substrate. Thereafter, drying is performed.

(Process of forming organic thin film layer)
In this step, an organic thin film layer is formed on the first electrode 6 by a coating method. In this step, an organic thin film layer (in this embodiment, the first organic thin film layer) provided at least in contact with the first electrode 6 is formed by a coating method. In the present embodiment, the first organic thin film layer 7 and the second organic thin film layer 9 are formed by a coating method.

It should be noted that the ink for forming the organic thin film layer (in this embodiment, the first organic thin film layer) provided in contact with the first electrode 6 from the time when the step of cleaning the surface of the first electrode is completed. The time until the start of application is preferably shorter, specifically, preferably within 2 hours, and more preferably within 30 minutes. The time when the step of cleaning the surface of the first electrode is completed is the time when the above-described drying is completed, and the time when ink application is started is the time when the first ink is applied.

In this step, first, the ink 22 containing the material to be the first organic thin film layer 7 is supplied to the region (recessed portion 5) surrounded by the partition walls 3 (see FIG. 4C). The ink is appropriately supplied by an optimum method in consideration of conditions such as the shape of the partition wall 3, the simplicity of the film forming process, and the film forming property. The ink may be supplied by, for example, an inkjet printing method, a nozzle coating method, a relief printing method, an intaglio printing method, or the like.

As shown in FIG. 4C, the ink 22 supplied to the region (recessed portion 5) surrounded by the partition wall 3 spreads on the first electrode and spreads to the side surface of the partition wall 3, but the partition wall 3 has liquid repellency. As a result, the ink can be prevented from overflowing into the adjacent recess. Thus, by providing the partition wall having liquid repellency, the ink can be reliably contained in the region (recessed portion 5) surrounded by the partition wall.

Next, the first organic thin film layer 7 is formed by solidifying the supplied ink 22 (see FIG. 5A). The ink may be solidified by, for example, natural drying, heat drying, or vacuum drying. In addition, when the ink contains a material that polymerizes by applying energy, the material constituting the organic thin film layer is polymerized by heating the thin film or irradiating the thin film with light after supplying the ink. Also good. Thus, by polymerizing the material constituting the organic thin film layer, it is used to form another organic thin film layer (second organic thin film layer) on the organic thin film layer (first organic thin film layer). The first organic thin film layer can be hardly solubilized in the ink.

As described above, in the present invention, in order to enhance the wettability of the surface of the first electrode 6 and to make the wettability uniform over the entire surface of the first electrode 6, the solvent of the ink is vaporized, When the film is thinned, the ink is dried while being held uniformly on the first electrode without being repelled locally. Therefore, the first organic thin film layer 7 having a uniform film thickness can be formed.

Next, a second organic thin film layer 9 that functions as a light emitting layer is formed. The second organic thin film layer 9 can be formed in the same manner as the first organic thin film layer 7. That is, three types of ink are supplied to the area surrounded by the partition wall 3, the ink containing the material that becomes the red light emitting layer 9, the ink containing the material that becomes the green light emitting layer 9, and the ink containing the material that becomes the blue light emitting layer 9. Each light emitting layer 9 can be formed by solidifying them.

(Step of forming the second electrode)
In this step, the second electrode is formed on the organic thin film layer. In the present embodiment, the second electrode 10 is formed on the entire display area where the organic EL element 4 is provided. That is, the second electrode 10 is formed not only on the second organic thin film layer 9 but also on the partition 3 and continuously formed over a plurality of organic EL elements. By forming the second electrode in this way, the second electrode 10 that functions as an electrode common to all the organic EL elements 4 is provided.

In the above description, the display device having a grid-like partition is described, but a stripe-like partition may be provided on the support substrate as described above. FIG. 6 is a plan view schematically showing an enlarged part of the display device of this embodiment provided with stripe-shaped partition walls. In the figure, the hatched area corresponds to the partition wall 3. FIG. 7 shows a cross-sectional shape of a display device in which the display device is cut along a plane perpendicular to the row direction X. The cross-sectional shape of the display device obtained by cutting the display device along a plane perpendicular to the column direction Y is the same as FIG. Since the display device of the present embodiment has substantially the same configuration as the display device of the above-described embodiment, only the different parts will be described below, and the corresponding parts will be denoted by the same reference numerals and redundant description will be given. May be omitted.

When stripe-like partition walls are provided, the partition walls are composed of, for example, a plurality of partition members extending in the column direction Y. The partition members are arranged at predetermined intervals in the row direction X. In the form in which the striped partition is provided, the striped recess is defined by the striped partition and the support substrate.

When stripe-shaped partition walls are provided, the organic EL elements 4 are arranged at predetermined intervals in the column direction Y in the respective recesses extending in the column direction Y.

The first electrodes 6 are arranged in a matrix similar to the above-described embodiment. The partition 3 is formed so that the end 3a covers one end of the first electrode 6 in the row direction X and the other end (see FIG. 1). As shown in FIG. 7, in the present embodiment, the end portion in the column direction Y of the first electrode 6 is not covered with the partition walls.

In the present embodiment, the first organic thin film layer 7 and the second organic thin film layer 9 are formed so as to extend to the respective recesses extending in the column direction Y and to be continuous over a plurality of organic EL elements. Is done.

<Configuration of organic EL element>
Below, the structure of an organic EL element is demonstrated in detail. The organic EL element has at least one light emitting layer as an organic thin film layer. As described above, the organic EL element may have, for example, a hole injection layer, a hole transport layer, an electron block layer, a hole block layer, an electron transport layer, and an electron injection layer between a pair of electrodes.

An example of a layer structure that can be taken by the organic EL element of the present embodiment is shown below.
a) anode / light emitting layer / cathode b) anode / hole injection layer / light emitting layer / cathode c) anode / hole injection layer / light emitting layer / electron injection layer / cathode d) anode / hole injection layer / light emitting layer / Electron transport layer / electron injection layer / cathode e) anode / hole injection layer / hole transport layer / light emitting layer / cathode f) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode g ) Anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode h) Anode / light emitting layer / electron injection layer / cathode i) Anode / light emitting layer / electron transport layer / electron injection Layer / Cathode (Here, the symbol “/” indicates that the layers sandwiching the symbol “/” are adjacently stacked. The same applies hereinafter.)
The organic EL element of this embodiment may have two or more light emitting layers. In any one of the layer configurations of a) to i) above, when the laminate sandwiched between the anode and the cathode is referred to as “structural unit A”, the configuration of the organic EL element having two light emitting layers is as follows. For example, the layer structure shown in j) below can be given. Note that the two (structural unit A) layer structures may be the same or different.
j) Anode / (Structural Unit A) / Charge Generation Layer / (Structural Unit A) / Cathode Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field.
Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), molybdenum oxide, and the like.

Further, when “(structural unit A) / charge generation layer” is “structural unit B”, examples of the configuration of the organic EL element having three or more light emitting layers include the layer configuration shown in the following k). .
k) anode / (structural unit B) x / (structural unit A) / cathode The symbol “x” represents an integer of 2 or more, and (structural unit B) x is a stack in which the structural unit B is stacked in x stages. Represents the body. A plurality of (structural units B) may have the same or different layer structure.

Note that an organic EL element in which a plurality of light emitting layers are directly laminated may be configured without providing a charge generation layer.

<Support substrate>
As the support substrate, a substrate that is not chemically changed in the process of manufacturing the organic EL element is suitably used. Examples of the material for the support substrate include glass, plastic, polymer film, silicon plate, and laminates thereof.

<Anode>
An electrode having optical transparency is used as the anode. As such an electrode, a metal oxide having a high electrical conductivity, a metal single layer film, or a laminated film can be used. Specifically, metal oxides such as indium oxide, zinc oxide, tin oxide, ITO (Indium Tin Oxide), and indium zinc oxide (abbreviation IZO); gold, platinum, silver, copper, aluminum, magnesium And a single layer film and a laminated film made of an alloy containing at least one of the above metals. In addition, as the configuration of the laminated film, for example, ITO \ Ag \ ITO, IZO \ Ag \ IZO, ITO \ APC (AgPdCu alloy) \ ITO, IZO \ APC (AgPdCu alloy) \ IZO, ITO \ AgCu alloy \ ITO, IZO \ AgCu alloy \ IZO, ITO \ AgMg alloy \ ITO, IZO \ AgMg alloy \ IZO, and the like. Examples of the method for producing the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

<Cathode>
A material for the cathode is preferably a material having a low work function, easy electron injection into the light emitting layer, and high electrical conductivity. Further, in the organic EL element configured to extract light from the anode side, the cathode material is preferably a material having a high reflectance with respect to visible light in order to reflect light emitted from the light emitting layer to the anode side by the cathode. Examples of such cathode materials include metals, alloys, graphite, and graphite intercalation compounds. Examples of the metal include alkali metals, alkaline earth metals, transition metals, and metals of Group 13 of the periodic table. Specific examples include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, and barium. , Aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like. Examples of the alloy include an alloy of two or more of the metals; and one or more of the metals, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin. Examples include alloys with one or more metals selected from the group consisting of magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium, and the like. -Magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, etc. The cathode may be a transparent electrode. Examples of the material thereof include conductive metal oxides such as indium oxide, zinc oxide, tin oxide, ITO, and IZO; polyaniline or a derivative thereof, polythiophene or a derivative thereof, and the like. Examples thereof include conductive organic substances. The cathode may have a stacked structure in which two or more layers are stacked. An electron injection layer may be used as the cathode.

Examples of the method for producing the cathode include a vacuum deposition method, a sputtering method, and an ion plating method.

The film thickness of the anode or cathode is appropriately set in consideration of the required characteristics and the simplicity of the film forming process, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm. .

<Hole injection layer>
Examples of the hole injection material constituting the hole injection layer include oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide; phenylamine compounds; starburst amine compounds; phthalocyanine compounds; amorphous carbon Polyaniline; and polythiophene derivatives.

Examples of the method for forming the hole injection layer include film formation from a solution containing a hole injection material. For example, a hole injection layer can be formed by applying a solution containing a hole injection material by a predetermined application method, and further evaporating and solidifying the solvent by drying and baking. Whether the organic material is a high molecular material or a soluble low molecular material, the production method of the present invention can be applied as long as a film is formed by a coating method.

The film thickness of the hole injection layer is appropriately set in consideration of required characteristics and process simplicity, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
Examples of the hole transport material constituting the hole transport layer include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amines in side chains or main chains, pyrazoline derivatives, arylamine derivatives, stilbene derivatives. , Triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) or derivative thereof, or poly (2,5-thienylene vinylene) Or the derivative | guide_body etc. can be mentioned.
Among these, hole transport materials include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amine compound groups in the side chain or main chain, polyaniline or derivatives thereof, polythiophene or derivatives thereof, poly Polymeric hole transport materials such as arylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and polyvinylcarbazole or derivatives thereof are more preferred. , Polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material. For example, a chlorine-based solvent such as chloroform, methylene chloride, dichloroethane, an ether-based solvent such as tetrahydrofuran, toluene, Examples thereof include aromatic hydrocarbon solvents such as xylene, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and mixtures thereof.

As a film formation method from a solution, the same coating method as the above-described film formation method of the hole injection layer can be exemplified. From the viewpoint of extending the life, it is preferable to form a film in the same atmosphere as in the adjacent layer forming step described above.

As the polymer binder to be mixed, those not extremely disturbing charge transport are preferable. In addition, a polymer binder having a weak absorption against visible light is preferably used. Examples of the polymer binder include polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane.

The film thickness of the hole transport layer is set in consideration of the required characteristics and the simplicity of the film forming process, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm. .

<Light emitting layer>
The light emitting layer usually contains an organic substance that mainly emits fluorescence and / or phosphorescence. The light emitting layer may further include a dopant that assists the organic matter. The dopant is added, for example, in order to improve the luminous efficiency and change the emission wavelength. In addition, the organic substance which comprises a light emitting layer may be a low molecular compound or a high molecular compound, and when forming a light emitting layer by the apply | coating method, it is preferable that a light emitting layer contains a high molecular compound. The number average molecular weight in terms of polystyrene of the polymer compound constituting the light emitting layer is, for example, about 10 ³ to 10 ⁸ . Examples of the light emitting material constituting the light emitting layer include the following dye materials, metal complex materials, polymer materials, and dopant materials.

(Dye material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives, and the like.

(Metal complex materials)
Examples of metal complex materials include central metals such as rare earth metals (for example, Tb, Eu, Dy), Al, Zn, Be, Ir, Pt, oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structures, and the like. The metal complex which has these ligands can be mentioned. Examples of such metal complexes include metal complexes having light emission from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyl zinc A complex, a porphyrin zinc complex, a phenanthroline europium complex, etc. can be mentioned.

(Polymer material)
Examples of polymer materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and the above-mentioned dye materials and metal complex light emitting materials. Can be mentioned.

The thickness of the light emitting layer is usually about 2 nm to 200 nm.

<Electron transport layer>
As the electron transport material constituting the electron transport layer, known materials can be used, for example, oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyano Anthraquinodimethane or derivative thereof, fluorenone derivative, diphenyldicyanoethylene or derivative thereof, diphenoquinone derivative, or metal complex of 8-hydroxyquinoline or derivative thereof, polyquinoline or derivative thereof, polyquinoxaline or derivative thereof, polyfluorene or derivative thereof, etc. Can be mentioned.

The film thickness of the electron transport layer is appropriately set in consideration of the required characteristics and the simplicity of the film forming process, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm. .

<Electron injection layer>
As the electron injecting material constituting the electron injecting layer, an optimum material is appropriately selected according to the type of the light emitting layer. Examples of the electron injection material include alkali metals; alkaline earth metals; alloys containing one or more of alkali metals and alkaline earth metals; oxides, halides, carbonates of alkali metals or alkaline earth metals; and A mixture of these substances can be mentioned. Examples of the alkali metal and its oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, Examples thereof include rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, and lithium carbonate. Examples of the alkaline earth metal and oxides, halides and carbonates thereof include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide and barium fluoride. Strontium oxide, strontium fluoride, magnesium carbonate and the like. The electron injection layer may have a stacked structure in which two or more layers are stacked, and examples thereof include LiF / Ca.

The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

Examples of the method for forming each organic thin film layer include a coating method such as a nozzle printing method, an ink jet printing method, a relief printing method, and an intaglio printing method, and a vacuum deposition method.

In the coating method, an ink containing an organic EL material to be each organic thin film layer is coated and formed, and further solidified to form an organic thin film layer. Examples of the ink solvent used in the coating method include chlorine solvents such as chloroform, methylene chloride, and dichloroethane, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. Examples thereof include ester solvents such as solvent, ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

When producing a color organic EL display device, an optimum microcavity effect can be obtained for each color by changing, for example, the film thickness of the hole injection layer for each color of RGB.

FIG. 9 shows an organic EL device using a green light emitting material that can obtain the photoluminescence (PL) spectrum (peak wavelength 517 nm) shown in FIG. 8 as a light emitting layer, when the film thickness of the hole injection layer is changed. It is the figure which simulated the EL spectrum. In the simulation, the configuration of the organic EL element is “anode / hole injection layer / hole transport layer / light emitting layer / cathode”, and the anode configuration is ITO / APC / ITO = 7 nm / 18 nm / 110 nm. The EL spectrum of light emitted in the direction perpendicular to the support substrate 2 was calculated with the configuration of NaF \ Al = 2 nm \ 1500 nm, the light emitting layer thickness of 100 nm, and the hole transport layer thickness of 20 nm.

For example, when the thickness of the hole injection layer is 40 nm, the peak wavelength is 526 nm, the CIE chromaticity coordinates x = 0.216, and y = 0.731. When the thickness of the hole injection layer is 50 nm, the peak wavelength is 542 nm, the CIE chromaticity coordinates x = 0.273, and y = 0.597. These two emission colors are clearly recognized as different colors.

Thus, even if the film thickness of the hole injection layer changes by only 10 nm, the spectrum of the original light emitting material itself changes greatly. This is because, due to the microcavity effect, the light wavelength band that is selectively enhanced under the condition of a constant viewing angle changes depending on the film thickness of the hole injection layer. As a matter of course, in a display device composed of organic EL elements having different hole injection layer thicknesses, variations in thickness appear as color unevenness on the display screen, so that the product yield decreases.

According to the production method of the present invention, it is possible to form a microcavity structure having an appropriate hole injection layer thickness, and it is possible to produce an organic EL element having a desired chromaticity.

First, a TFT substrate on which a first electrode 6 formed of a laminated film in which an ITO layer having a thickness of 7 nm, an APC layer having a thickness of 18 nm, and an ITO layer having a thickness of 110 nm were sequentially laminated was prepared from the side close to the support substrate. (See FIG. 3A). However, in FIG. 3A, the boundary between the ITO layer and the APC layer is omitted, and the entire laminated film is illustrated as the first electrode 6.

Next, a negative photosensitive resin solution (ZPN2464 manufactured by Nippon Zeon Co., Ltd.) is mixed with the liquid repellent 2 (Daikin liquid repellent Optoace (registered commercial method) HP series) to prepare a photosensitive resin composition containing the liquid repellent. did. The ratio of the solid content concentration of the liquid repellent to the total solid content of the photosensitive resin composition excluding the liquid repellent {(total solid content of the photosensitive resin composition excluding the liquid repellent / liquid repellent) × 100} is 0.2% (weight). ). Next, a photosensitive resin composition containing a liquid repellent was applied on the surface of the prepared TFT substrate by a spin coater, and prebaking was performed by heating at 110 ° C. for 90 seconds on a hot plate. By this pre-baking treatment, the solvent of the photosensitive resin composition was evaporated to form a partition wall forming film (see FIG. 3B).

Next, using a proximity exposure machine, the partition wall forming film was exposed through a predetermined mask at an exposure amount of 100 mJ / cm ² (see FIG. 3C). Then, post-exposure baking (PEB) was performed by heating at 110 ° C. for 60 seconds, and development was performed for 100 seconds using a developer (SD-1 (TMAH 2.38 wt%) manufactured by Tokuyama Corporation).
Furthermore, it heated at 230 degreeC as post-baking for 30 minutes, the resin was hardened, and the forward taper-shaped partition was formed (refer FIG. 4A). The partition wall thickness was 0.6 μm. The contact angle between the partition wall top surface and pure water was 75 °, and the contact angle between the partition wall top surface and anisole was 39 °. The contact angle between the surface of the first electrode and pure water was 25 °. When the partition wall was formed to have a thickness of 1.0 μm, a reverse-tapered partition wall was formed. In this embodiment, a forward tapered partition is used, but a reverse tapered partition may be used.

Next, a hole injection layer was formed as a first organic thin film layer. The same developer as used for developing the partition walls (SD-1 (TMAH 2.38 wt%) manufactured by Tokuyama Corporation) was diluted with pure water to 0.5 wt%, and the substrate surface was washed. By this cleaning, the contact angle between the surface of the first electrode and pure water was reduced to 5 ° or less, and sufficient wettability could be imparted to the surface of the first electrode (ITO thin film). At this time, the contact angle between the top surface of the partition wall and anisole was 35 °. Next, an ink (poly (ethylenedioxythiophene) (PEDOT) / polystyrene sulfonic acid (PSS) aqueous dispersion having a solid content concentration of 1.5% by weight (AI 4083, manufactured by Bayer) using an inkjet apparatus (Litex 142P manufactured by ULVAC). ) Was applied to each recess (see FIG. 4C). Since the partition wall 3 has liquid repellency, the ink could be accommodated in the region (the recessed portion 5) surrounded by the partition wall 3 without overflowing into the adjacent recessed portion. The ink was held on the first electrode uniformly without being repelled locally at the first electrode. The substrate was baked at 200 ° C. to form a hole injection layer having a uniform thickness (see FIG. 5A).

Next, a hole transport layer was formed as a second organic thin film layer. The polymer hole transport compound 1 was mixed in a mixed solvent of cyclohexylbenzene and 4-methyl-anisole (also known as 4-methoxy-toluene) at a composition ratio (weight) of 8: 2 so that the ratio was 0.28% by weight. Thus, an ink for forming a hole transport layer was obtained. The ink for forming the hole transport layer was applied into a predetermined recess using an inkjet apparatus (Lilex 142P manufactured by ULVAC) to obtain a coating film having a thickness of 20 nm. The substrate provided with this coating film was heated in a nitrogen atmosphere at 190 ° C. for 60 minutes to insolubilize the coating film, and then naturally cooled to room temperature to obtain a hole transport layer. (The hole transport layer is omitted in FIG. 5)

Next, three types of light emitting layers were formed. First, a polymer light-emitting material that emits red light was mixed with an organic solvent so that its concentration was 0.8 wt% to prepare red ink. Similarly, a green ink was prepared by mixing a polymer light emitting material that emits green light with an organic solvent so that the concentration thereof was 0.8 wt%. Then, a blue light was prepared by mixing a polymer light emitting material that emits blue light with an organic solvent so that its concentration was 0.8 wt%. Each of these red, green, and blue inks was applied into a predetermined recess using an inkjet device (Lilex 142P manufactured by ULVAC). Since the ink was repelled by the top surface of the partition wall having a high contact angle, the ink was prevented from overflowing to the adjacent area through this top surface and was accommodated in the recess. By firing this substrate at 130 ° C., a light-emitting layer having a uniform thickness was formed (see FIG. 5C).

Next, a NaF layer (2 nm), an Mg layer (2 nm), an Al layer (1500 nm), and an Ag layer (100 nm) were sequentially laminated by a vacuum deposition method to form a second electrode (cathode). Then, the sealing substrate was bonded together, the organic EL element was sealed, and the display apparatus was produced.

In addition, the organic thin film layer of each organic EL element was formed by the film thickness shown in the following table 1 according to the kind of each organic EL element.

The EL spectrum of each organic EL element produced as described above is shown in FIGS. 10, 11, and 12 together with the photoluminescence (PL) spectrum of the light emitting material. 10 shows the EL spectrum of the red organic EL element and the PL spectrum of the red light emitting material, FIG. 11 shows the EL spectrum of the green organic EL element and the PL spectrum of the green light emitting material, and FIG. 12 shows the EL spectrum of the blue organic EL element and the blue light emitting material. The PL spectrum of each is shown. The PL spectrum of each luminescent material was obtained by measuring the PL spectrum of a sample in which only the luminescent layer was formed on the glass substrate. It can be confirmed that the EL spectrum becomes sharper than the PL spectrum of the light emitting material due to the microcavity effect, and the peak wavelength is shifted.

The light emission characteristics of the obtained organic EL element are shown in Table 2 below. As shown in Table 2 below, it was confirmed that desired chromaticity coordinate values were obtained.

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Support substrate 3 Partition 3a End of partition 4 Organic EL element 5 Recess 6 First electrode 7 First organic thin film layer (hole injection layer)
8 Partition formation film 9 Second organic thin film layer (light emitting layer)
DESCRIPTION OF SYMBOLS 10 2nd electrode 12 Support substrate 13 Partition 15 Recess 16 First electrode 17 Ink 18 Organic thin film layer 19 Residue 21 Photomask 22 Ink

Claims (3)

1. A support substrate, a partition wall defining a partition set in advance on the support substrate, and a plurality of organic electroluminescence elements respectively provided in the partition defined by the partition wall, each organic electroluminescence element is A method of manufacturing a display device including a first electrode, an organic thin film layer, and a second electrode in this order from the support substrate side,
   A step of preparing a support substrate on which a partition formed by patterning a photosensitive resin composition containing a liquid repellent by a photolithography method and a first electrode; and
   Cleaning the surface of the first electrode with a solution containing at least one of oxalic acid, phosphoric acid, acetic acid, nitric acid, and hydrogen chloride, or a developer of the photosensitive resin composition;
   Forming an organic thin film layer on the first electrode by a coating method;
   Forming a second electrode on the organic thin film layer.
2. The method for manufacturing a display device according to claim 1, wherein the first electrode is indium tin oxide, and the solution is a mixed solution of phosphoric acid, acetic acid, and nitric acid.
3. The method for manufacturing a display device according to claim 1, wherein the first electrode is indium zinc oxide, and the solution is a mixed solution of phosphoric acid, acetic acid and nitric acid, or an oxalic acid aqueous solution.

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