JP2007080545A - Manufacturing method of organic electroluminescent display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL display device free from coating unevenness in case a light-emitting layer is formed in an ink-jet system. <P>SOLUTION: Pixels 20 are arranged in length and breadth directions in a lattice shape on an array substrate 10, and luminous materials are discharged from nozzles 36 of ink-jet heads 52, 54 at positions corresponding to the respective pixels 20 to form a luminous layer. The luminous layer is formed by discharging a luminous material on the array substrate 10 while moving the first head 52 along a first diagonal line direction A, and then as a next process, the luminous material is discharged on the array substrate 10 while moving the second head 54 along a second diagonal line direction B to overcoat the luminous material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic EL display device in which a light emitting layer is formed by a selective coating method such as an ink jet method.

  A recent inkjet coating method has been developed and used for coating a light emitting layer of a pixel in an organic EL display device.

For example, in Patent Document 1, a light emitting layer is formed by ejecting a light emitting material intermittently in a first direction from a nozzle of an inkjet head to a pixel of an organic EL display device, and further, a light emitting layer of another color is formed. There has been proposed a manufacturing method in which a light emitting material is formed by intermittently discharging a light emitting material from a nozzle in a second direction substantially orthogonal to the first direction.
JP 2003-109754 A

  However, in the case of a manufacturing method in which a light emitting layer is formed by a selective coating method such as the ink jet method as described above, it is difficult to reduce coating unevenness between adjacent pixels. May appear as unevenness.

  In view of the above problems, the present invention provides a method for manufacturing an organic EL display device that does not cause uneven coating when a light emitting layer is formed by a selective coating method.

  The invention according to claim 1 is an organic EL display device in which pixels are arranged vertically and horizontally in a grid pattern on an array substrate, and a light emitting material is discharged from a nozzle of a selective application head to a position corresponding to each pixel. In the method of manufacturing an organic EL display device in which a light emitting layer is formed on each pixel, the light emitting material is ejected while moving the selective coating head along a first direction which is a first diagonal direction of the array substrate. Forming a light emitting layer on each pixel, and discharging the light emitting material while moving the selective application head along a second direction which is a second diagonal direction of the array substrate. And a step of overcoating the light-emitting material on the light-emitting layer.

  The invention according to claim 2 is an organic EL display device in which pixels are arranged vertically and horizontally in a grid pattern on an array substrate, and a light emitting material is discharged from a nozzle of a selective application head to a position corresponding to each pixel. In the method of manufacturing an organic EL display device in which a light emitting layer is formed on each pixel, the light emitting material is ejected while moving the selective coating head along the first direction of the array substrate to cause each pixel to emit a light emitting layer. And forming the light emitting material on the light emitting layer of each pixel by discharging the light emitting material while moving the selective coating head along a second direction orthogonal to the first direction of the array substrate. And a step of overcoating the luminescent material.

  In the manufacturing method of the organic EL display device of the present invention, the light emitting material is ejected while moving the selective coating head along the first direction to form the light emitting layer, and the second direction is different from the first direction. When the selective coating head is moved along the direction, the light emitting material is discharged and overcoating is performed, so that uneven coating of the light emitting material does not occur. Therefore, luminance unevenness does not occur when lighting.

  FIG. 2 is a longitudinal sectional view schematically showing a partial structure of the organic EL display device, and here, in particular, shows a longitudinal sectional view of the array substrate 10 for one pixel and before forming the light emitting layer. Yes.

  On the array substrate 10, a scanning line, a signal line arranged perpendicular to the scanning line, a pixel TFT (thin film transistor) which is a switching element arranged near the intersection of the signal line and the scanning line, And a pixel 20 connected to the drive transistor 14 (referred to as a drive transistor connected to the signal line via the pixel TFT).

  The pixel TFT and the drive transistor 14 are formed on a support substrate 12 made of a glass substrate, and a thin film transistor having a top gate structure is employed here. These TFTs include a polysilicon semiconductor layer P formed on the support substrate 12, a gate electrode G disposed via the polysilicon semiconductor layer P and the first insulating film 16, a first insulating film 16 and a second insulating film 16. A source electrode S in contact with the source region of the polysilicon semiconductor layer P through the insulating film 18 and a drain electrode D in contact with the drain region of the polysilicon semiconductor layer P through the first insulating film 16 and the second insulating film 18 It has. The source electrode of the pixel TFT is connected to the signal line, and the gate electrode is connected to the scanning line. The drain electrode of the pixel TFT is connected to the gate electrode G of the drive transistor 14. The source electrode S of the driving transistor 14 is connected to the constant potential terminal, and the drain electrode D is connected to the lower electrode 26 of the pixel 20.

  The pixel 20 is disposed on the third insulating film 22 disposed on the second insulating film 18. That is, the lower electrode 26 of the pixel 20 is formed in the upper layer of the third insulating film 22 and is connected to the drain electrode D of the driving transistor 14 through the contact hole 28 provided in the third insulating film 22. The lower electrode 26 is made of ITO (Indium Tin Oxide), which is a light transmissive conductive material, and functions as an anode here.

  A partition wall 24 made of an acrylic resin is formed on the upper layer of the lower electrode 26. The partition wall 24 partitions adjacent pixels 20 in the horizontal direction. In order to form the partition wall 24 made of this acrylic resin, mask exposure is performed with UV light.

  A photoactive layer including at least a light emitting layer is stacked on the lower electrode 26 exposed through the opening of the partition wall 24. This photoactive layer is sandwiched between an upper electrode (not shown) of the cathode disposed opposite to the lower electrode 26. This photoactive layer may be composed of a multilayer structure of a hole transport layer, an electron transport layer, and an organic light emitting layer formed for each color, or each layer is functionally combined. It may be formed with a layered structure. In the present embodiment, the hole transport layer 30 and the organic light emitting layer 32 are constituted by two layers.

  The hole transport layer 30 is formed of an aromatic amine derivative, a polythiophene derivative, or a polyaniline derivative, and the organic light emitting layer is formed of an organic compound that emits red (R), green (G), or blue (B). For example, when a polymer material is employed, the organic light emitting layer 32 is configured by laminating PPV (polyparaphenidene vinylidene), a polyfluorene derivative, or a precursor thereof.

  In forming the hole transport layer 30 and the organic light emitting layer 32, first, a material for forming the hole transport layer 30 is dropped by an ink jet method. Next, a light emitting material for forming the organic light emitting layer 32 is dropped thereon.

  An ink jet type coating apparatus for forming the organic light emitting layer 32 will be described with reference to FIG.

  A table 50 for mounting the array substrate 10 is provided. A first ink-jet head (referred to as a first head) 52 and a second ink-jet head (referred to as a second head) 54 are respectively arranged outside the diagonal direction of the table 50. The first head 52 has the same width as the length in the diagonal direction B of the array substrate 10 to be coated, and nozzles 36 for discharging red, green, and blue light emitting materials on the lower surface thereof along the width direction. Are lined up. The second head 54 has a similar configuration.

  The first head 52 moves along the first diagonal direction A of the array substrate 10 placed on the table 50.

  The second head 54 moves along a second diagonal direction B that intersects the first diagonal direction A, and the angle at which the first diagonal direction A and the second diagonal direction B intersect is θ. To do. In both the first head 52 and the second head 54, the distance between the nozzle 36 and the array substrate 10 is set to about 300 μm.

  Next, the process of forming the organic light emitting layer 32 using this inkjet type coating apparatus will be described.

  As shown in FIG. 1, the array substrate 10 in which the partition wall 24 is formed on the lower electrode 26 is placed on the table 50.

  Next, while moving the first head 52 along the first diagonal direction A, the light emitting material is intermittently ejected to a position corresponding to the pixel 20. In this case, when the nozzle 36R that discharges the red light emitting material discharges to the position of the red pixel 20R according to the moving speed of the first head 52, and the green nozzle 36G reaches the green pixel 20G. The green light emitting material is discharged to the blue pixel 36B, and when the blue nozzle 36B comes to the green pixel 20B, the blue light emitting material is discharged. Further, as shown in FIG. 1, since the number of pixels 20 to be applied at the corners of the array substrate 10 is small, the light emitting material is discharged only at the central portion of the first head 52 and the necessary nozzles 36, and as the movement is performed, The number of nozzles 36 to be ejected is gradually increased, and the light emitting material is ejected from all nozzles 36 in the width direction of the first head 52 when it reaches the substantially central portion of the array substrate 10, that is, the position in the second diagonal direction B. Let Thereafter, the number of nozzles 36 that are discharged in reverse with the movement of the first head 52 is gradually reduced to a minimum number at the opposite corner of the array substrate 10. Then, the first coating is finished.

  Next, after the coating by the first head 52 is completed, the second head 54 is moved along the second diagonal direction B. This coating method is the same as that of the first head 52.

  In this way, the light emitting material discharged from the second head 54 is overcoated on the first light emitting layer coated by the first head 52 for each pixel 20, thereby applying the coating. It is possible to suppress the unevenness from being visually recognized, and to suppress the visual recognition of the coating unevenness.

  In addition, since application is performed at a predetermined angle with respect to the wiring direction of the signal lines, it is possible to reduce the visibility of streaky unevenness.

  Therefore, when the organic EL display device using the array substrate 10 is turned on, it is possible to effectively suppress the occurrence of luminance unevenness.

  In the above-described embodiment, coating is performed along the diagonal direction, but the present invention is not limited to this, and the same effect can be obtained by scanning a predetermined angle along one direction with respect to one side of the array substrate. it can.

  In the above embodiment, the width of the head and the width of the array substrate parallel to the major axis direction of the head are matched. However, the present invention is not limited to this. You may apply | coat to the whole surface by scanning once.

  Moreover, although it demonstrated taking as an example apply | coating to the array substrate corresponding to each panel, you may form a some panel on one array substrate.

  The hole transport layer 30 is also applied in the same manner before the organic light emitting layer 32 is applied. Thus, the present invention can be applied to other photoactive layers.

  Further, although the ink jet method has been described, other selective coating methods may be used.

  Next, a method for manufacturing the organic EL display device according to the second embodiment will be described with reference to FIG.

  The difference between this embodiment and the first embodiment lies in the arrangement of the first head 52 and the second head 54.

  As shown in FIG. 3, in this embodiment, the first head 52 moves along the Y-axis direction of the array substrate 10, and the second head 54 moves along the X-axis direction. That is, the first head 52 and the second head 54 move so as to be orthogonal.

  Also in the present embodiment, the light emitting material is applied twice for one pixel, and coating unevenness does not occur in the entire array substrate 10. Therefore, luminance unevenness does not occur when lighting.

  In each of the above embodiments, the first head 52 and the second head 54 are provided for each movement direction. Instead of this, only one head is provided and the table 50 is set to θ when each coating is finished. It may be rotated by 90 degrees or 90 degrees to enable coating in two directions with one head.

It is a top view which shows the manufacturing method of the 1st Embodiment of this invention. It is an expansion longitudinal cross-sectional view of the pixel part in an organic electroluminescence display. It is a top view which shows the manufacturing method of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Array substrate 14 Drive transistor 20 Pixel 24 Partition 30 Hole transport layer 32 Organic light emitting layer 50 Table 52 1st head 54 2nd head

Claims (6)

An organic EL display device in which pixels are arranged vertically and horizontally in a grid pattern on an array substrate, and a light emitting material is ejected from a nozzle of a selective coating head to a position corresponding to each pixel to form a light emitting layer on each pixel In the manufacturing method of the organic EL display device,
Forming a light emitting layer on each pixel by discharging the light emitting material while moving the selective application head along a first direction which is a first diagonal direction of the array substrate;
The light emitting material is discharged while moving the selective application head along a second direction which is a second diagonal direction of the array substrate, and the light emitting material is further coated on the light emitting layer of each pixel. Process,
A method for producing an organic EL display device, comprising: An organic EL display device in which pixels are arranged vertically and horizontally in a grid pattern on an array substrate, and a light emitting material is ejected from a nozzle of a selective coating head to a position corresponding to each pixel to form a light emitting layer on each pixel In the manufacturing method of the organic EL display device,
Forming the light emitting layer on each pixel by discharging the light emitting material while moving the selective coating head along the first direction of the array substrate;
The light emitting material is ejected while moving the selective coating head along a second direction orthogonal to the first direction of the array substrate, and the light emitting material is further coated on the light emitting layer of each pixel. And a process of
A method for producing an organic EL display device, comprising: Equipped with different selective application heads for each moving direction,
The organic EL display device according to claim 1, wherein the second direction is applied by the other selective application jet after coating by the first selective application head in the first direction. Manufacturing method. The array substrate is placed on a rotatable table,
The first direction is applied by the selective application head, and then the table is rotated by a predetermined angle, and the second direction is applied by the same selective application head. The manufacturing method of the organic electroluminescence display of description. The pixel has three colors of R, G, and B,
The method of manufacturing an organic EL display device according to claim 1, wherein the coating in the two directions is performed for each color. The pixel has three colors of R, G, and B,
The method for manufacturing an organic EL display device according to claim 1, wherein the three colors are applied simultaneously in three colors.

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