JP2004327241A - Manufacturing method for organic electroluminescence display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an organic EL display panel having excellent processing efficiency, wherein a boundary of each scan is not easily visible when using an ink jet method. <P>SOLUTION: Overlapped parts 4a, 4b exist between n-th applied region 1a by an ink jet method and n+1-th applied region 1b, and between n+1-th region 1b and n+2-th region 1c respectively. An electrode 3a applied at n-th application and an electrode 3b applied at n+1-th application in the overlapped part 4a, and the electrode 3b applied at n+1-th application and an electrode 3c applied at n+2-th application in the overlapped part 4b are alternately arranged for every column when viewed in the a scanning direction (a column direction in the figure). Thereby, the boundary of each applied region becomes non-linear, and delicate unevenness of luminance and colors for every scan can be made not easily visible. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an organic electroluminescence display device in which a plurality of organic electroluminescence elements are arranged in a matrix.
[0002]
[Prior art]
In recent years, LCDs have been widely used as flat panel displays from mobile phones to large televisions. However, LCDs are not self-luminous and have a narrow viewing angle, and require a light source such as a backlight, which limits power consumption reduction. Therefore, as a display device replacing the LCD, for example, a self-luminous display device using organic electroluminescence (hereinafter, referred to as organic EL) has been studied. The organic EL element is a self-luminous type in which an EL layer emits light by supplying a current to an organic EL layer provided between an anode and a cathode, and does not require a backlight or the like unlike an LCD. It is excellent in terms of thickness reduction, size reduction, low power consumption, and the like, and is expected as a mainstream of flat panel displays.
[0003]
The structure of the organic EL display device will be described with reference to FIG. In the display area, the gate signal lines 11 and the source signal lines 12 are arranged in a matrix, and pixels are formed in a portion surrounded by the gate signal lines 11 and the source signal lines 12. In each pixel, an organic EL element 14 using an organic EL is provided for a light emitting layer 13, a driving TFT 16 for supplying a current from a power supply line 15 to the organic EL element 14, and ON / OFF of the driving TFT 16. Are formed respectively. When a current is supplied from the power supply line 15 to the organic EL element 14, the light emitting layer 13 emits light in each color, and the brightness can be adjusted by controlling the current value.
[0004]
Three power supply lines 15 are provided corresponding to R, G, and B of the pixel. The R power supply line 15R is connected to the organic EL element 14 having the red light emitting layer 13 (R) and the G power supply line. 15G is connected to the organic EL element 14 having the green light emitting layer 13 (G), and the B power supply line 4 is connected to the organic EL element 14 having the blue light emitting layer 13 (B). The organic EL element 14 emits different colors depending on the luminescent material, but at the same time, the luminous efficiency is different. Therefore, by providing the power supply line 15 for each color and supplying a current suitable for each color, an optimal full-color display is achieved. The enabled organic EL element 14 is formed by depositing a low molecular or high molecular organic EL material on the pixel. As this method, in the case of a low molecular material, generally, a method of depositing an organic EL material on a desired pixel is performed. On the other hand, in the case of a polymer material, a method of fine patterning using an inkjet method, which can discharge and apply droplets having a diameter on the order of μm with high resolution and can perform high-definition patterning, has attracted attention.
[0005]
FIG. 8 is a schematic cross-sectional view showing a manufacturing process of the organic EL display device. Here, for convenience of explanation, only a pixel portion (a cross section taken along line DD in FIG. 7) is shown. When an inkjet method is used for manufacturing an organic EL display device, an ink composition containing an organic EL material is ejected from an ink head and patterned and applied on an electrode to form a light emitting layer. As shown in FIG. 8A, a gate insulating film 18 is formed on the glass substrate 10 and covers a gate electrode (not shown). The source signal line 12 is formed on the gate insulating film 18, and an insulating film 19 made of SiNx is formed thereon. On the insulating film 19, a transparent electrode 20 is patterned for each pixel.
[0006]
Reference numeral 21 denotes a protective film made of SiO2, which is formed on the insulating film 19 and overlaps the peripheral portion of the transparent electrode 20 of the organic EL device. That is, although the protective film 21 covers the peripheral portion of the transparent electrode 20, it is removed in most parts including the central part of the transparent electrode 20. Reference numeral 22 denotes a bank layer formed of a novolak resin formed on the protective film 21, and is formed to be thicker than the protective film 21 and the insulating film 19.
[0007]
Since the organic EL, which is a light emitting material, is applied to the region surrounded by the bank layer 22 by an inkjet method, the bank layer 22 is formed along the outer edge of the transparent electrode 20 so as to surround the transparent electrode 20. Note that the bank layer 22 may be an insulator, and may be formed of an organic resin or an inorganic resin other than the novolak resin.
[0008]
Next, as shown in FIG. 8B, an ink composition containing an organic EL material is applied on a substrate provided with the bank layer 22 by an ink-jet method to form the light-emitting layer 13. Various organic EL materials are known. For example, a conjugated polymer precursor is used. At this time, the light-emitting material is polymerized by heat treatment, and the R, G, and B colors are changed for each pixel. The light emitting layer 13 is formed.
[0009]
Next, a counter electrode 23 made of Al or Cr is laminated on the light emitting layer 13 as shown in FIG. The counter electrode 23 is formed over the entire display area, and is supplied with a predetermined voltage. If the counter electrode 23 is formed of a metal layer, light emission by the light emitting layer 13 becomes possible. Therefore, the counter electrode 23 may be formed of a metal other than Al or Cr. If the light emitting layer 13 is made of a metal layer having a high light reflectance such as Cr or Cr, light from the light emitting layer 13 can be efficiently used for display, and display with higher luminance can be realized. When a current equal to or higher than the threshold is supplied to the transparent electrode 20, the light emitting layer 13 emits light, and the light can be observed from the glass substrate 10 side. Further, as shown in FIG. 8D, an adhesive resin layer 24 made of epoxy resin or the like is laminated on the counter electrode 23, and is covered with a cover glass 25 forming the back surface.
[0010]
FIG. 9 shows a state of application of the organic EL composition by a conventional inkjet method. In the example shown in this figure, it is assumed that the organic EL composition is applied on the pixel electrodes from the top to the bottom of the drawing, and the ink head is sequentially scanned from the left to the right in the drawing. Reference numerals 1a, 1b, and 1c denote application areas to be applied in one scan of the inkjet system, and indicate the application areas to be applied at the n-th, n + 1-th, and n + 2 times, respectively. 2a is a boundary between the n-th application area and the (n + 1) -th application area, and 2b is a boundary between the (n + 1) -th application area and the (n + 2) -th application area. Note that FIG. 9 shows a case when viewed as a whole, and the application areas 1a, 1b, and 1c are color-coded for convenience of description. Is an R, G, B ink composition on which an organic EL composition is applied on a pixel electrode.
[0011]
FIG. 10 is an enlarged schematic view of the application state of the organic EL composition. Here, for convenience of explanation, it is assumed that each of the application areas 1a, 1b, and 1c has a width of eight rows of electrodes, and only four rows of electrodes are shown for the application areas 1a and 1c. Reference numerals 3a, 3b, and 3c denote electrodes applied in the n-th, (n + 1) -th, and (n + 2) -th scans by the inkjet method, respectively. The electrodes 3a, 3b, and 3c are actually coated with ink compositions of respective colors corresponding to R, G, and B for each individual electrode. Here, for simplicity, the colors are color-coded according to the number of inkjet scanning. As shown in FIG. 10, at the boundary 2a between the application region 1a and the application region 1b, the electrodes 3a and 3b applied at the nth and (n + 1) th times are linearly arranged in the application direction across the boundary 2a. At the boundary 2b between the coating region 1b and the application region 1c, the electrodes 3b and 3c to be applied at the (n + 1) th and (n + 2) th times are linearly arranged in the application direction with the boundary 2b interposed therebetween.
[0012]
In the ink jet method, coating is performed by sequentially scanning the substrate while simultaneously ejecting a plurality of points by a head having a certain width in consideration of processing efficiency. However, the application state such as the film thickness of the organic EL material to be applied is not completely uniform for each scan, and the characteristics of the application state of the head slightly differ for each scan. Further, for example, when scanning is performed from the left end of the substrate as shown in FIG. 9, the right end of the application region 1a in the n-th scan and the left end of the application region 1b in the (n + 1) -th scan are in contact with each other. There may be a slight difference in the state, and the application state of the electrodes 3a, 3b, and 3c is not completely uniform in FIG. For this reason, a slight difference in brightness between the boundary portions 2a and 2b between the application regions may be visually recognized. Such a phenomenon causes luminance unevenness and color unevenness at a boundary portion of the application region in each scan, and has led to a decrease in display quality. In this case, the characteristics of the coating state of the head may be made completely uniform, but such control is actually very difficult due to the characteristics of the material.
[0013]
In order to solve such a problem, there has been proposed a method of improving coating accuracy in each scan and making it difficult to visually recognize a boundary portion of a coating region in each scan. By making the area larger than the pixel area where the electrodes are located, and further providing a dummy area around the pixel area, the molecular partial pressure of the solvent evaporated from the droplets is equalized in the pixel area, and the organic EL material is made uniform. A method of applying to the surface is disclosed.
[0014]
[Patent Document 1]
JP-A-2002-222695
[Problems to be solved by the invention]
However, the method described in Patent Literature 1 has a problem that the display surface is darkened because the effective display area is reduced by the application region and the dummy region which are not related to display.
[0016]
An object of the present invention is to provide a method for manufacturing an organic EL display panel in which boundaries between scans are hardly visually recognized and an excellent processing efficiency is obtained when an inkjet method is used.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method in which a composition containing an organic EL material is sequentially scanned over a plurality of electrodes provided in a matrix on a substrate in a row direction or a column direction on the substrate by an inkjet method. In the method for manufacturing an organic EL display device in which a light-emitting layer is formed by coating while applying, the inkjet method has a coating region consisting of a plurality of rows or columns of a matrix that can be simultaneously coated for each scan, and n is one or more. When it is an integer, the application region scanned at the n-th time and the application region scanned at the (n + 1) -th time have an overlapping portion at a boundary portion in the scanning direction, and a part of the electrode existing in the overlapping portion is n. At the time, the remaining electrodes present in the overlap portion are applied with the composition at the (n + 1) th time, and the electrode applied at the nth time and the electrode applied at the (n + 1) th time are: Characterized in that as interspersed in serial overlapping portion.
[0018]
According to this configuration, when the organic EL material is applied by the inkjet method, it is possible to eliminate a linear boundary of the application region in each scan, and it is difficult to visually recognize a change in luminance at the boundary portion, resulting in luminance unevenness and color unevenness. Display quality can be prevented from deteriorating.
[0019]
Further, according to the present invention, in the method for manufacturing an organic EL display device having the above-described configuration, the number of the electrodes applied in the n-th application is from the n-th application area to the (n + 1) -th application area. , And the number of the electrodes applied at the (n + 1) th application increases from the nth application area toward the (n + 1) th application area.
[0020]
According to this configuration, the boundary of the application region in each scan can be changed in a stepwise manner, so that a deterioration in display quality such as luminance unevenness and color unevenness can be more effectively prevented.
[0021]
Further, according to the present invention, in the method for manufacturing an organic EL display device having the above-described configuration, the width of the overlapping portion is 20 to 40% of the width of the application region.
[0022]
According to this configuration, a method of manufacturing an organic EL display device that makes it difficult to visually recognize the boundary of the application region in each scan, effectively prevents deterioration in display quality such as luminance unevenness and color unevenness, and has excellent processing efficiency. Can be provided.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged schematic view of the applied state of the organic EL composition of the first embodiment. In FIG. 1, the organic EL composition is applied onto the pixel electrodes from the top to the bottom of the drawing by the ink jet method as in FIG. 8, and the ink head is sequentially scanned from the left to the right in the drawing. I do. The same parts as those in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.
[0024]
In FIG. 1, overlapping portions 4a and 4b exist between the nth application region 1a and the (n + 1) th application region 1b and between the (n + 1) th application region 1b and the (n + 2) th application region 1c, respectively. . Here, for simplicity, the overlapping portions 4a and 4b have a width corresponding to three rows of electrodes. The electrodes 3a and 3b are arranged alternately in the overlapping section 4a for each row when viewed in the coating direction. The electrodes 3a, 3b, and 3c are actually coated with the ink composition of each color corresponding to red (R), green (G), and blue (B) for each electrode. For simplicity, the colors are classified according to the number of scans of the inkjet.
[0025]
The application state of the electrodes existing in the overlapping portion will be described in detail with reference to FIG. FIG. 2 is an enlarged view of the overlapping portion in the present embodiment. Here, for convenience of explanation, only the overlap portion 4a of the n-th application region 1a and the (n + 1) th application region 1b is shown, and the overlap portion 4a has a width corresponding to nine rows of electrodes. Further, each electrode on the glass substrate 10 is described separately for each color of R, G, and B for each column as in the actual case.
[0026]
In FIG. 2, the R electrode row at the left end of the overlapping portion 4a is arranged in the order of the electrode 3a applied nth time, the electrode 3b applied n + 1th time, the electrode 3a applied nth time from the drawing. In. The second G electrode row from the left end is arranged in the order of 3b, 3a, 3b..., And the third B electrode row from the left end is arranged in the order of 3a, 3b, 3a. That is, for each column of electrodes corresponding to each color of R, G, and B, an electrode 3a applied for the nth time and an electrode 3b applied for the (n + 1) th time are present alternately, and the electrode 3a applied for the nth time is present. And the electrode 3b applied at the (n + 1) th time is scattered throughout the overlapping portion 4a. Although the overlapping portion 4b has not been described, the electrode 3b applied in the (n + 1) th time and the electrode 3c applied in the (n + 2) th time are scattered throughout the overlapping portion 4b.
[0027]
As a result, the boundary between the electrode applied in any scan of the inkjet and the electrode applied in the next scan becomes non-linear, making it difficult to visually recognize subtle brightness unevenness and color unevenness in each scan. it can. FIG. 3 shows the applied state of the organic EL composition of the present embodiment. Compared to FIG. 9, the boundaries between the coating region 1a and the coating region 1b and between the coating region 1b and the coating region 1c are not linear due to the presence of the overlapping portions 4a and 4b. This makes it difficult to be visually recognized, and can prevent the display quality from deteriorating.
[0028]
The widths of the overlapping portions 4a and 4b are not particularly limited, and can be arbitrarily set according to the widths of the application regions 1a, 1b and 1c. Generally, the wider the overlapping portions 4a and 4b, the harder the boundary is to be visually recognized, but the processing efficiency by the ink jet decreases. Conversely, the narrower the width, the higher the processing efficiency. Preferably, the width is 20 to 40% of the width of the region. In the present embodiment, in the overlapping portions 4a and 4b, the electrodes 3a and 3b and the electrodes 3b and 3c are applied so as to be alternately arranged in each column and each row. As shown in FIG. 4A, it is possible to apply every three electrodes 3a in the overlapping portion 4a, or to apply two electrodes 3a and 3b alternately as shown in FIG. 4B. Any pattern can be selected without departing from the range.
[0029]
Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 5 is an enlarged view showing the substrate applied by the method for applying the organic EL composition of the second embodiment. The configuration of each part on the substrate is common to FIG.
[0030]
In the present embodiment, the electrode 3a, the electrode 3a, and the electrode 3b are arranged repeatedly in the order of the left end column of the overlapping portion 4a, the electrode 3a and the electrode 3b are arranged alternately in the center column, and the electrode 3b, The electrode 3b and the electrode 3a are repeatedly arranged in this order. That is, the number of the electrodes 3a existing in the overlapping portion 4a decreases from the application region 1a toward the application region 1b, and conversely, the number of the electrodes 3b increases from the application region 1a toward the application region 1b. Has been applied. In the overlapping portion 4b, the number of the electrodes 3b decreases from the application region 1b toward the application region 1c by the same pattern, and conversely, the number of the electrodes 3c increases from the application region 1b toward the application region 1c. It is applied as follows.
[0031]
FIG. 6 shows the applied state of the organic EL composition of the present embodiment. In the overlapping portion 4a, the coating state gradually increases from the coating region 1a toward the coating region 1b, and in the overlapping portion 4b, the coating state gradually decreases from the coating region 1b toward the coating region 1c. Has become. This makes it possible to gradually change the delicate difference in the application state generated for each scan in the overlapping portions 4a and 4b, and to reduce the deterioration in display quality such as luminance unevenness and color unevenness by gradation as compared with the first embodiment. It can be prevented more effectively.
[0032]
Note that the arrangement pattern of the electrodes 3a, 3b, 3c is not limited to this embodiment, as long as the difference in the coating state for each scan in the overlapping portions 4a, 4b can be changed stepwise. Good.
[0033]
In the above embodiments, the case where the inkjet head scans in the column direction of the matrix is described, but the method of applying the organic EL composition of the present invention can be applied to the case where the inkjet head scans in the row direction. Of course.
[0034]
【The invention's effect】
According to the present invention, a composition containing an organic electroluminescent material is applied onto a plurality of electrodes provided in a matrix on a substrate while sequentially scanning the substrate in a row direction or a column direction by an ink jet method to emit light. In the method of manufacturing an organic electroluminescent display device for forming a layer, in the inkjet method, there is a coating region consisting of a plurality of rows or columns of a matrix that can be coated simultaneously for each scan, and n is an integer of 1 or more. The application area scanned at the n-th time and the application area scanned at the (n + 1) -th time have an overlapping portion at a boundary portion parallel to the scanning direction, and the electrode existing in the overlapping portion is the n-th time or the (n + 1) -th time. The electrode to which the composition is applied to any one and the n-th application and the n + 1-th application are repeated a plurality of times. When the organic EL material is applied by the inkjet method, it is possible to eliminate a linear boundary of the application region in each scan, since the organic EL material is applied by the inkjet method. This makes it difficult to visually recognize a change in luminance at the boundary portion, thereby preventing deterioration in display quality such as luminance unevenness and color unevenness.
[0035]
In addition, the number of electrodes applied to the n-th application decreases from the n-th application area to the (n + 1) -th application area, and the number of electrodes applied to the (n + 1) -th application is n. Since the increase is made from the first application area side to the (n + 1) th application area side, the boundary of the application area in each scan can be changed stepwise, and the display quality such as luminance unevenness and color unevenness is deteriorated. Can be more effectively prevented.
[0036]
In addition, since the width of the overlapping portion is set to be 20 to 40% of the width of the application region, it is difficult to visually recognize the boundary of the application region in each scan, and the display quality such as luminance unevenness and color unevenness is reduced. It is possible to provide a method of manufacturing an organic EL display device which can prevent the organic EL device from being environmentally prevented and has excellent processing efficiency.
[Brief description of the drawings]
FIG. 1 is an enlarged view showing a pattern of an electrode applied by a method for applying an organic EL composition according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of an electrode present in an overlapping portion according to the embodiment.
FIG. 3 is a schematic view showing a state of application of the organic EL composition of the present embodiment.
FIG. 4 is an enlarged view showing another application pattern of the present embodiment.
FIG. 5 is an enlarged view showing a pattern of an electrode applied by a method for applying an organic EL composition according to a second embodiment of the present invention.
FIG. 6 is a schematic diagram showing a state of application of the organic EL composition of the present embodiment.
FIG. 7 is a plan view showing the structure of the organic EL display device.
FIG. 8 is a schematic sectional view illustrating a manufacturing process of the organic EL display device.
FIG. 9 is a schematic view showing a state of application of a conventional organic EL composition.
FIG. 10 is an enlarged view showing a pattern of an electrode applied by a conventional method for applying an organic EL composition.
[Explanation of symbols]
1a. n-th application area 1b. The (n + 1) th application area 1c. n + 2nd application area 2a. Boundary 2b. Boundary 3a. The electrode 3b. The electrode 3c. The electrodes 4a. Overlapping part 4b. 10. Overlapping part Substrate 13. Light emitting layer 14. Organic EL device 20. Transparent electrode 22. Bank layer 23. Counter electrode

Claims (3)

On a plurality of electrodes provided in a matrix on a substrate, a composition containing an organic electroluminescent material is applied by an inkjet method while sequentially scanning the substrate in a row direction or a column direction to form a light-emitting layer. In a method for manufacturing an organic electroluminescence display device,
The inkjet method has an application area consisting of a plurality of rows or columns of a matrix that can be simultaneously applied for each scan, and when n is an integer of 1 or more, the application area to be scanned nth time and the n + 1th time The application region to be scanned has an overlapping portion in a boundary portion in a scanning direction, and a part of the electrode present in the overlapping portion is an n-th time, and the remaining electrode present in the overlapping portion is an n + 1-th time. The method of manufacturing an organic electroluminescent display device, wherein the electrode to which the composition is applied and applied n-th time and the electrode applied to n + 1-th time are scattered in the overlapping portion. The number of the electrodes applied in the n-th application region decreases from the n-th application region side to the (n + 1) -th application region side when the electrodes present in the overlap portion are viewed in each row or column in the scanning direction. 2. The method according to claim 1, wherein the number of the electrodes applied in the (n + 1) th application area increases from the nth application area to the (n + 1) th application area. 3. The method according to claim 1, wherein a width of the overlapping portion is 20 to 40% of a width of the application region. 4.

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