JP2004055159A - Method for manufacturing organic el element, and organic el element displaying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an organic EL element wherein organic EL materials are prevented from being color-mixed among adjacent barriers, when the element is manufactured such that the materials are coated among the barriers formed on a substrate, and also to provide a displaying device with the element. <P>SOLUTION: Hole transport layers 10 are formed by drying a hole transport material 8 by means of heating the substrate 2 after the hole transport material 8 is selectively supplied to each element space SP. As a result, the adhesion of the hole transport material 8 to tops of the barriers is prevented, and liquid repellency treatment to the barrier tops are carried out. Specifically, layers 12 containing fluorine are formed on the tops of the barriers 6. Further, following the liquid repellency treatment, the organic EL materials 14R are supplied to spaces among the barriers. In this process, the transfer of the materials to other spaces among the barriers is hindered so that the color mixing of the materials having a plurality of colors is effectively prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an organic EL element by applying an organic EL (electroluminescence) material on a substrate in a predetermined pattern to manufacture an organic EL element, and an organic EL display device.
[0002]
[Prior art]
A conventional organic EL device is manufactured as described below. First, a transparent ITO (indium tin oxide) film is formed on a surface of a transparent substrate such as a glass substrate (hereinafter, simply referred to as a “substrate”). Next, the ITO film formed on the substrate is patterned and formed into a plurality of striped first electrodes by using a photolithography technique. This first electrode corresponds to an anode. Next, an electrically insulating partition wall that protrudes above the substrate so as to surround the stripe-shaped first electrode is formed by photolithography.
[0003]
Then, after forming the hole transport layer on the first electrode, an organic EL material is ejected between the partition walls from a nozzle of an ink jet system, and the organic EL material is applied on the stripe-shaped first electrode between the partition walls. Specifically, a hole transport material is formed on the entire surface of the substrate by spin coating, and a hole transport layer is formed on the first electrode by performing a drying process. Are formed on the first electrode via the hole transport layer as described below. That is, the red organic EL material is applied to the stripe-shaped first electrodes between the partition walls by the nozzle for the red organic EL material. A green organic EL material is applied to one of the first electrodes adjacent to the first electrode to which the red organic EL material is applied by a nozzle for a green organic EL material. Further, a blue organic EL material is applied by a nozzle for the blue organic EL material on the next first electrode adjacent to the first electrode to which the green organic EL material is applied. A red organic EL material is applied on the next first electrode adjacent to the first electrode on which the blue organic EL material is applied. As described above, the red, green, and blue organic EL materials are individually applied on the first electrode in that order.
[0004]
Next, a plurality of stripe-shaped second electrodes that are opposed to the first electrodes so as to be orthogonal to the first electrodes are formed on the substrate by vacuum evaporation so that a plurality of stripe-shaped second electrodes are formed between the first electrodes and the second electrodes. EL material is sandwiched. This second electrode corresponds to a cathode. In this way, an organic EL element capable of full-color display in which the first electrode and the second electrode are arranged in a simple XY matrix is manufactured.
[0005]
[Problems to be solved by the invention]
However, when the organic EL material is applied between the partition walls on the substrate and the organic EL material applied between the partition walls moves between the surrounding partition walls beyond the partition walls, the other organic color of the surrounding color is removed. There is a problem that a plurality of colors of organic EL materials are mixed into the EL materials and mixed.
[0006]
The present invention has been made in view of the above problems, and when an organic EL material is applied between partition walls formed on a substrate to manufacture an organic EL element, the color of the organic EL material is mixed between adjacent partition walls. It is an object of the present invention to provide a method for manufacturing an organic EL element and an organic EL display device, which can prevent the occurrence of an organic EL element.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a partition wall forming step of forming partition walls on a substrate corresponding to a predetermined pattern, and forming a hole transport layer by selectively supplying a hole transport material between the partition walls. After the first coating step, a liquid repellent step of performing a liquid repellent treatment on the top of the partition wall, and the first coating step and the liquid repellent step, an organic EL material is supplied between the partition walls to form an organic EL layer. A second coating step.
[0008]
In the invention configured as described above, before the organic EL material is supplied between the partitions, the liquid repellent treatment is performed on the tops of the partitions. For this reason, when the organic EL material is supplied between the partition walls, even if the organic EL material tries to move beyond the top of the partition walls, the organic EL material moves between the other partition walls by the liquid repellent-treated top of the partition walls. Is prevented, and color mixing of a plurality of organic EL materials is prevented. Here, it is important to perform the lyophobic treatment on the tops of the partition walls in order to sufficiently exhibit the color mixing prevention effect as described above. Therefore, particularly in the present invention, a hole transport material is selected between the partition walls. To form a hole transport layer. That is, as described in the section of "Prior Art", a spin coating method has been widely used as a method of forming the hole transport layer, and the hole coating is formed on the entire surface of the substrate by using this spin coating method. Since the transport material was attached, the liquid repellent treatment could not be performed on the top of the partition wall. On the other hand, in the present invention, the application range of the hole transport material is limited between the partition walls, thereby preventing the hole transport material from adhering to the top of the partition walls. Therefore, the lyophobic treatment can be reliably performed on the top of the partition wall, and the color mixture can be reliably prevented.
[0009]
Here, in the first coating step, the first nozzle may be moved relative to the substrate along the space between the partition walls while discharging the hole transport material from the first nozzle. As described above, since the hole transport material from the first nozzle is applied by flowing between the partition walls, the hole transport material is prevented from rebounding when the hole transport material is applied to the substrate, and the application of the hole transport material is performed. Control becomes easy. Further, by preventing the hole transporting material from rebounding, the hole transporting material is securely prevented from adhering to the top of the partition wall, and the liquid repellency treatment on the partition top portion can be further ensured.
[0010]
Also, in the second coating step, similarly to the first coating step, the second nozzle is relatively moved with respect to the substrate along the space between the partition walls while discharging the organic EL material from the second nozzle. Since the organic EL material from the two nozzles is applied by flowing between the partition walls, the organic EL material is prevented from rebounding when the organic EL material is applied to the substrate, and application control of the organic EL material is facilitated. Also, by preventing the organic EL material from rebounding, the organic EL material is prevented from being mixed between the surrounding partition walls.
[0011]
Further, since the liquid repellent treatment is performed on the top of the partition walls, even if the organic EL material is supplied between the partition walls until the organic EL material becomes overfilled, the organic EL material does not flow between the adjacent partition walls and color mixing can be prevented. For this reason, the permissible application amount at the time of applying the organic EL material can be increased by the lyophobic treatment and the extra supply to the top of the partition wall.
[0012]
Further, in order to achieve the above object, the present invention is characterized by having an organic EL element manufactured by the manufacturing method according to any one of claims 1 to 5.
[0013]
In this specification, “hole transport layer” is a concept including not only “hole transport layer” in a narrow sense but also “hole injection layer”. Means a material for constituting the “hole transport layer”.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 are views showing one embodiment of a method for manufacturing an organic EL device according to the present invention. In this embodiment, first, as shown in FIG. 1A, an ITO film is formed on a substrate 2 such as a glass substrate or a transparent plastic substrate, and then a plurality of striped first electrodes are formed by using a photolithography technique. Is formed by patterning. This first electrode corresponds to an anode, and FIGS. 1 and 2 show three types of first electrodes 4R, 4G, and 4B corresponding to red, green, and blue. The first electrode is preferably a transparent electrode. In addition to the above-described ITO film, a tin oxide film, a composite oxide film of indium oxide and zinc oxide, or the like can be used.
[0015]
Next, an electrically insulating partition (bank) 6 is formed by using, for example, photolithography or the like, and the space between the first electrodes (anodes) 4R, 4G, and 4B is filled (partition forming step). Accordingly, it is possible to prevent color mixing of an organic EL material formed later and prevent light leakage from between pixels. Here, the material constituting the partition 6 is not particularly limited as long as it has durability with respect to a hole transporting material and an organic EL material described later, and for example, an organic material such as an acrylic resin, an epoxy resin, and a polyimide. Materials, inorganic materials such as liquid glass, and the like can be used.
[0016]
Then, the hole transporting material 8 is selectively supplied between the partition walls, that is, to each element space SP, and the hole transport layer 10 is formed on the first electrodes (4R, 4G, 4B) in each element space SP. (First coating step). Specifically, a hole transport material 8 prepared by dissolving an organic compound for forming the hole transport layer 10, for example, PEDT (polyethylene dioxythiophene) -PSS (poly-styrene sulfonate) with a solvent is prepared in advance, and a nozzle is prepared. After being selectively supplied to each element space SP by a scanning method (FIG. 2B), the hole transport material 8 is dried by applying a heat treatment to the substrate 2 to form the hole transport layer 10. (FIG. (C)). As a device for selectively supplying the hole transport material 8 to each element space SP in this manner, for example, a coating device as shown in FIG. 3 can be used. The configuration of the coating apparatus will be described later with reference to FIG. Further, as a drying device for drying the hole transport material 8, a baking device used for manufacturing a semiconductor device, a liquid crystal display device, or the like can be used.
[0017]
Next, the top of the partition 6 is fluorinated (liquid-repellent) by performing a plasma treatment using CF ₄ gas (fluorocarbon gas) on the top of the partition 6. Thus, as shown in FIG. 1D, a fluorine-containing layer (a layer made of a material containing fluorine) 12 is formed on the top of the partition 6 (liquid repellent step). The lyophobic treatment is not limited to the fluorinating treatment, but may be any treatment having lyophobicity to an organic EL material described later. For example, the partition 6 may be formed by applying a polymer or a solvent. An impregnation treatment in which the constituent material swells can be used. Specifically, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), and polyvinylidene fluoride (PTFE) (PVDF) may be impregnated by applying a fluorine resin selected from the group to make the liquid repellent. Alternatively, the hole transporting material 8 may be impregnated by applying an alcohol, such as toluene, xylene, or benzene, which is insoluble in water, which is the main material of the solvent of the hole transporting material 8, to make it lyophobic.
[0018]
Next, a red organic EL material 14R is supplied between partition walls corresponding to the first electrode 4R by a nozzle scan method to form an organic EL layer 16R on the first electrode 4R via the hole transport layer 10 ( Second coating step). Specifically, as shown in FIG. 1E, the organic EL material 14R is supplied between the partition walls until the space overflows from between the partition walls corresponding to the first electrode 4R and a margin is formed on the top of the partition wall 6. . At this time, since the fluorine-containing layer 12 is formed on the top of the partition 6 and the top of the partition 6 is subjected to liquid repellency treatment, the organic EL material 14R does not flow over the partition 6 and flow between the surrounding partitions. It stops inside the top of the partition 6 and is in a prosperous state. As a device for supplying the organic EL material 14R, for example, a coating device described in JP-A-2002-75640 can be used, and the nozzle of this coating device corresponds to the “second nozzle” of the present invention. I do.
[0019]
When the supply of the organic EL material 14R is completed, the organic EL material 14R is dried by applying a heat treatment to the substrate 2 by a baking device or the like to form the organic EL layer 16R (FIG. 2A).
[0020]
Next, a green organic EL layer 16G is formed on the first electrode 4G via the hole transport layer 10, and a blue organic EL layer 16B is further formed on the first electrode 4B via the hole transport layer 10. Is formed (FIG. 2B). Note that the steps for forming the same are the same as those for the case of red color, and the description is omitted here. The organic EL layer may be formed for each color, or the three colors of the organic EL materials 14R, 14G, and 14B may be simultaneously supplied and dried.
[0021]
When the formation of the organic EL layers 16R, 16G, and 16B for the three colors is completed as described above, the stripes are orthogonal to the first electrodes 4R, 4G, and 4B, as shown in FIG. A plurality of second electrodes 18 are formed in parallel on the substrate 2 by a vacuum evaporation method or the like. With this configuration, the “organic EL element” of the present invention is formed, that is, the organic EL layer 16R is provided between the first electrodes 4R, 4G, and 4B functioning as anodes and the second electrode 18 functioning as cathodes. , 16G, and 16B. Further, an organic EL display device capable of full-color display in which the first electrodes 4R, 4G, 4B and the second electrode 18 are arranged in a simple XY matrix is manufactured. In this embodiment, a sealing layer 20 made of a sealing material such as an epoxy resin, an acrylic resin, and a liquid glass is formed on the substrate 2 so as to prevent deterioration and damage of each organic EL element. ing.
[0022]
As described above, in this embodiment, after the hole transport material 8 is selectively supplied to each element space SP, the hole transport material 8 is dried by applying a heat treatment to the substrate 2. Since the transport layer 10 is formed, the hole transport layer 10 can be formed without attaching the hole transport material 8 to the top of the partition 6. After the liquid repellent treatment is performed on the tops of the partition walls 6, the organic EL materials 14R, 14G, and 14B are supplied between the partition walls. Even if an attempt is made to move beyond the top, the presence of the fluorine-containing layer 12 formed on the top of the partition 6 prevents movement of the organic EL material between the other partitions, thus effectively mixing colors of the organic EL materials of a plurality of colors. Can be prevented.
[0023]
Further, by performing the lyophobic treatment on the top of the partition 6 in this manner, the following operation and effect can be obtained. That is, in order to avoid color mixing of the organic EL material, the partition 6 is so arranged that the space between the partitions, that is, the volume of the element space SP is larger than the amount of the organic EL material 14R, 14G, 14B supplied between the partitions. The height may be increased to prevent overflow of the organic EL materials 14R, 14G, and 14B from the element space SP. However, simply increasing the height of the partition 6 causes a problem that the size of the organic EL element is increased, and the step between the top of the partition 6 and the organic EL layers 16R, 16G, and 16B increases, and the second electrode 18 is formed at the step. However, there is a problem that the wire is easily broken and the product quality is deteriorated. On the other hand, in the present embodiment, the organic EL materials 14R, 14G, and 14B can be overlaid on the tops of the partition walls 6 by subjecting the tops of the partition walls 6 to liquid repellency treatment. The coating amount can be increased. In other words, even if the height of the partition 6 is relatively low, an organic EL material in an amount necessary for forming an organic EL layer can be applied, and a small-sized and good quality organic EL element is manufactured. It becomes possible.
[0024]
Next, an embodiment of a coating apparatus for selectively supplying the hole transport material 8 to each element space SP will be described with reference to FIG. FIG. 3 is a diagram showing an embodiment of a coating apparatus suitable for the method for manufacturing an organic EL device according to the present invention. As shown in the figure, this coating apparatus moves the stage 40 in a predetermined direction (left and right direction in the figure) on a stage 40 on which the substrate 2 on which the organic EL element is formed as described above is mounted. A stage moving mechanism section 42, an alignment mark detection section 44 for detecting the position of an alignment mark formed on the substrate 2, a supply unit 48 for supplying the hole transport material 8 to the three nozzles 46a to 46c, A nozzle moving mechanism 50 for moving the three nozzles 46a to 46c in a predetermined direction (perpendicular to the plane of the drawing) and a control unit 52 for controlling each unit of the apparatus.
[0025]
As shown in the drawing, the supply unit 48 includes a supply source 54 for storing the hole transport material 8, and the supply source 54 is connected to three supply units 56a to 56c by piping. ing. Further, these three supply units 56a to 56c have the same configuration, and the supply units 56a pressurize the hole transport material 8 stored in the supply source 54 to the nozzles 46a to 46c, respectively. It is configured to discharge toward. Specifically, each of the supply units 56a to 56c includes a pump 58 for extracting the hole transport material 8 from the supply source 54, a flow meter 60 for detecting a flow rate of the hole transport material 8, And a filter 62 for removing foreign substances therein. As described above, in this embodiment, the hole transporting material 8 is configured to be discharged from the nozzles 46a to 46c toward the substrate 2, and these nozzles 46a to 46c serve as the "first nozzle" of the present invention. It is functioning.
[0026]
In addition, the nozzle moving mechanism unit 50 holds the three nozzles 46a to 46c in a state of being juxtaposed by a holding member (not shown), and can change and set an application pitch interval between the nozzles 46a to 46c. . Therefore, the application pitch can be changed according to the arrangement state of the partition walls formed on the substrate 2.
[0027]
Further, as the alignment mark detection unit 44, for example, a CCD camera can be adopted. That is, upon receiving an instruction from the control unit 52, the alignment mark detection unit 44 captures images of alignment marks (not shown) formed at the four corners of the substrate 2, respectively, and outputs image data of these captured alignment marks. Is output to the control unit 52. On the other hand, the control unit 52 calculates the position of the alignment mark based on the image data captured by the alignment mark detection unit 44. In addition, since the layout data of the first electrodes 4R, 4G, 4B, the partition 6, and the like designed by using CAD (Computer Aided Design) is given to the control unit 52 in advance, the control unit 52 has the alignment mark. Based on the calculation result of the position and the layout data of the partition wall 6 given in advance, the application start point, that is, the application start position where the application of the hole transport material 8 is started is calculated.
[0028]
The control unit 52 controls the stage moving mechanism 42 so as to move the stage 40 in a predetermined direction (the left-right direction in FIG. 3) by a predetermined amount, and moves the nozzles 46a to 46c perpendicular to the stage 40. The nozzle moving mechanism 50 is controlled to move the nozzles 46a to 46c relative to the substrate 2 two-dimensionally so as to move the nozzles 46a to 46c by a predetermined amount in a direction (perpendicular to the plane of the drawing). In addition, along with the relative movement of the nozzles 46a to 46c with respect to the substrate 2, the control unit 52 flows out the hole transport material 8 at a predetermined flow rate from the nozzles 46a to 46c in accordance with the detection values a to c from the flow meters 60. Commands d to f are output to the pumps 58 as described above.
[0029]
In the coating apparatus configured as described above, when the substrate 2 before being subjected to the coating process of the hole transport material 8 is placed on the stage 40, the control unit 52 controls the apparatus based on a detection value from each unit of the apparatus. An operation command is given to each part, and the hole transport material 8 is applied between the partition walls (element space SP) as follows.
[0030]
First, in response to a mark imaging command from the control unit 52, the alignment mark detection unit 44 images the alignment marks at the four corners of the substrate 2 placed on the stage 40, and sends the image data to the control unit 52. Output. The control unit 52 receiving this calculates the position of the alignment mark based on the image data, and further calculates the application start point. Then, in response to a movement command from the control unit 52, the stage moving mechanism unit 42 and the nozzle moving mechanism unit 50 operate to position the nozzles 46a to 46c at the start points. Thereby, the three nozzles 46a to 46c are positioned one by one between the three partition walls (element space SP).
[0031]
When the application can be started in this way, the control unit 52 instructs each pump 58 to start flowing the hole transport material 8 from each of the nozzles 46a to 46c into the space between the partition walls (element space SP) on the substrate 2. At the same time, the nozzles 46a to 46c are moved in the direction perpendicular to the plane of FIG. 3 so that the hole transporting material 8 flows along the partition walls on the substrate 2 while flowing along the partition walls. Thereby, the hole transport material 8 is simultaneously poured into the three element spaces SP. When the nozzles 46a to 46c move to the end of the element space SP, a stop command is given to each pump 58, and holes from each of the nozzles 46a to 46c to the element space SP on the substrate 2 are sent. The pouring of the transport material 8 is stopped, and a stop command is given to the nozzle moving mechanism unit 50 to stop the nozzle movement. The control unit 52 controls the application amount according to the moving speed of the nozzles 46a to 46c so that the application amount of the hole transport material 8 at each point in the stripe-shaped element space SP is uniform. ing. In this manner, the application of the hole transport material 8 to the three rows of element spaces SP is completed. Further, the hole transport material 8 poured onto the hole transport layer 14 in the element space SP flows and is leveled so as to spread into the element space SP due to its own viscosity, and the hole transport material 8 having a uniform thickness. Is formed. In addition, the thickness of the hole transport material 8 poured into the element space SP can be adjusted by the amount of the hole transport material 8 to be poured.
[0032]
Next, the stage 40 is pitch-fed by three rows of the element spaces SP so that the hole transport material 8 can be applied to the next three rows of the element spaces SP. In the first three rows of the grooves 11 described above, one end of the element space SP is set as a coating start position, and the other end is set as a coating stop position, and the nozzles 46a to 46c are moved along the partition walls to form respective element spaces. The hole transport material 8 is poured into the SP, but in the next three rows of the element space SP, the nozzles 46a to 46c are moved in the direction opposite to the above moving direction so that one end moves from the other end of the element space SP to the sum. Then, the hole transport material 8 is poured into each element space SP.
[0033]
By repeatedly performing such an operation, the hole transport material 8 can be poured between the partition walls (element space SP). In addition, since the hole transport material 8 from the nozzles 46a to 46c is applied by flowing into the space between the partition walls (element space SP), the hole transport material 8 rebounds when the hole transport material 8 is applied to the substrate 2. Can be prevented. Further, application control of the hole transport material 8 is also facilitated. Therefore, from these facts, the hole transport material 8 can be selectively flowed between the partition walls (element space SP) without attaching the hole transport material 8 to the top of the partition wall 6. As described above, the coating apparatus in FIG. 3 is a useful apparatus for the above-described method for manufacturing an organic EL element.
[0034]
The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the method for manufacturing an organic EL device according to the above embodiment, the liquid repellent treatment is performed on the top of the partition 6 after the application of the hole transport material 8. The order of the processing may be changed.
[0035]
Further, in the above embodiment, the coating apparatus of FIG. 3 is used to apply the hole transporting material 8 between the partition walls. However, the configuration of the coating apparatus is not limited to this, and the hole transporting material 8 is provided between the partition walls. Any device such as an ink jet coating device may be used as long as the coating device can selectively supply the transport material 8.
[0036]
【The invention's effect】
As described above, according to the present invention, by selectively supplying a hole transport material between the partition walls to form a hole transport layer, it is possible to perform liquid repellency treatment on the partition wall tops, On the other hand, since the organic EL material is supplied between the partition walls after the lyophobic treatment, the supplied organic EL material moves between the other partition walls beyond the top of the partition wall. Thus, it is possible to effectively prevent the color mixing of the organic EL materials of a plurality of colors.
[Brief description of the drawings]
FIG. 1 is a view showing one embodiment of a method for manufacturing an organic EL device according to the present invention.
FIG. 2 is a view showing one embodiment of a method for manufacturing an organic EL device according to the present invention.
FIG. 3 is a view showing an embodiment of a coating apparatus suitable for the method for manufacturing an organic EL device according to the present invention.
[Explanation of symbols]
2 ... substrate 6 ... partition walls 8 ... hole transport material 10 ... hole transport layer 12 ... fluorine-containing layer 14R ... organic EL materials 16R, 16G, 16B ... organic EL layers 46a to 46c ... (first) nozzle SP ... element space (Between partition walls)

Claims (6)

A partition wall forming step of forming a partition wall on the substrate corresponding to a predetermined pattern,
A first coating step of selectively supplying a hole transport material between the partition walls to form a hole transport layer;
A liquid-repellent step of performing a liquid-repellent treatment on the top of the partition wall,
A method of manufacturing an organic EL device, comprising: a step of supplying an organic EL material between the partition walls to form an organic EL layer after the first coating step and the liquid-repellent step. 2. The organic EL according to claim 1, wherein the first application step is a step of moving the first nozzle relative to the substrate along the space between the partition walls while discharging the hole transport material from the first nozzle. Device manufacturing method. In the first coating step, after the hole transport material is supplied to a space formed between the partition walls, a drying process is performed on the hole transport material in the space to form the hole transport layer. A method for manufacturing an organic EL device according to claim 1. 4. The method according to claim 1, wherein the second application step is a step of moving the second nozzle relative to the substrate along the space between the partition walls while discharging the organic EL material from a second nozzle. 3. The method for producing an organic EL device according to item 1. In the second coating step, the organic EL material is supplied between the partition walls until the overflow occurs from the space between the partition walls to form a fill on the top of the partition wall. The method for producing an organic EL device according to any one of claims 1 to 4, wherein the organic EL layer is formed on the hole transport layer by performing a drying treatment. An organic EL display device comprising an organic EL element manufactured by the manufacturing method according to claim 1.

Images