JP2009064642A - Manufacturing method of organic electroluminescent display device, and manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a high-quality organic electroluminescent display device in which an emission color failure caused by the mixing of light-emitting materials between pixel regions is prevented, damage to a light-emitting layer in the pixel region is prevented, and the unevenness of a thickness of the light-emitting layer between the pixel regions and in the pixel regions is reduced. <P>SOLUTION: In the manufacturing method of the organic electroluminescent display device, a light-emitting layer 56 is formed by injecting a light-emitting layer drop 54 containing a light-emitting material into the pixel region 30 demarcated by banks 31 on a substrate 3, and the manufacturing method comprises a soluble solution coating process in which a solvent drop 52 having viscosity lower that of than a light-emitting layer drop 54 is coated on the whole region of the pixel region 30 and a light-emitting solution injecting process in which the light-emitting layer drop 54 is injected into the pixel region 30 coated with the solvent drop 52 by the soluble solution coating process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an organic electroluminescence display device in which a light emitting layer is formed on a substrate, and a manufacturing device.

  In recent years, liquid crystal display devices have been actively used as flat panel displays in a wide variety of fields. However, the contrast and color change greatly depending on the viewing angle, and the use of a light source such as pack light reduces power consumption. There are still major problems such as difficulty and there are limits to thinning and weight reduction.

  Therefore, in recent years, a self-luminous display device using organic electroluminescence (hereinafter referred to as organic EL) is expected as a display device that replaces the liquid crystal display device.

  In the organic EL element constituting the organic EL, when an electric current is passed through the organic EL layer sandwiched between the anode and the cathode, organic molecules (functional materials) constituting the organic EL layer emit light. An organic EL display device using an EL element is self-luminous, and is excellent in terms of thinning, lightening, and low power consumption. In addition, because of its wide viewing angle, it attracts much attention as a candidate for the next generation flat panel display. In addition, taking advantage of the thinness and wide viewing angle, practical application is spreading as a sub-display for portable music devices and mobile phones.

  In general, the manufacturing method of this organic EL element differs depending on the type of the functional material forming the organic EL element. For example, when a polymer organic compound is used as the functional material, the functional material is formed by a wet method such as a spin coating method, a screen printing method, an ink jet method, and a spray coating method. On the other hand, when a low molecular organic compound is used as the functional material, the film is often formed by a dry method such as a vacuum deposition method or a sputtering method.

  In the plurality of film forming methods described above, the ink jet method generally has a higher use efficiency of the film forming material than other film forming methods, and can be patterned without using a mask. It has an excellent point that it can easily cope with the manufacture of an organic EL display device. Therefore, research on production of an organic EL element using an ink jet method has been actively conducted.

  For example, Patent Document 1 discloses that for each pixel region partitioned by banks (partitions) in a substrate shape, a hole injecting and transporting layer including a conductive molecule between electrodes, and a light-emitting layer using an inkjet method. A method for producing an organic EL element having a light emitting layer containing organic molecules is disclosed.

  However, the formation of the light emitting layer using the conventional inkjet method disclosed in Patent Document 1 has the following problems.

  First, the ink jet method has a problem that color mixture of liquid materials occurs between adjacent pixel regions. Specifically, the inkjet system includes a functional material for forming a light emitting layer on a substrate in order to form a display region regularly arranged in the order of blue light emitting pixels, green light emitting pixels, and red light emitting pixels. A partition (bank) for holding the liquid material (droplet) in the pixel region is formed. Here, when a droplet corresponding to the emission color is discharged and filled in each pixel region, during or after the filling, the liquid material passes over the partition wall and leaks to the adjacent pixel region, and liquids of different emission colors are obtained. A light emitting layer that cannot emit a desired color may be formed by mixing with the material.

  In order to solve the above problem of color mixing of liquid materials, there is a method of imparting liquid repellency to the partition walls. For example, in the method disclosed in Patent Document 2, non-affinity (liquid repellency) of the partition wall is formed in the pixel region by performing plasma treatment on the partition wall using a gas containing a fluorine compound or the like. A liquid material containing a functional material that is higher than the electrode can be confined in the pixel region.

  As yet another example, the partition wall can be formed of a material containing a fluorine compound without performing plasma treatment on the partition wall, thereby imparting liquid repellency to the liquid material containing the functional material. Further, if the substrate surrounded by the partition walls is subjected to plasma treatment using UV treatment or oxygen gas to impart lyophilicity to the liquid material, the affinity between the partition wall and the substrate surface in the pixel region for the liquid material The difference in property becomes remarkable, and the liquid material is more reliably held in the pixel region.

  However, new problems arise when liquid repellency is imparted to the partition walls. In the step of forming the partition wall, the partition wall material cannot be completely removed from the surface of the pixel region, or the liquid-repellent partition layer component is partially scattered in the subsequent step, thereby The liquid repellency is exhibited above, and the liquid material containing the functional material may not spread. In such a case, a portion where the light emitting layer is not formed, that is, a defect of the light emitting layer appears on the substrate surface in the pixel region.

  In addition, the problem of the defect of the light emitting layer described above can be caused not only by the liquid repellency of the partition walls but also by other factors. Other factors will be specifically described below.

  First, in the organic EL element, a carrier transport layer (a hole transport layer and an electron transport layer) for allowing sufficient electrolysis to be applied to the light emitting layer is formed. This carrier transport layer generally has lower electrical resistance and higher conductivity than the light emitting layer. In addition, a functional material layer called a carrier blocking layer for preventing carriers from passing through the light emitting layer without contributing to light emission is provided between the carrier transporting layer and the light emitting layer. May be formed. Since this carrier blocking layer generally has low electrical conductivity, it is often formed in a very thin film as compared with the light emitting layer.

  Here, consider a method of manufacturing an organic EL element in which a hole transport layer, a light emitting layer, and a cathode are laminated in a pixel region surrounded by a partition using an inkjet method. The hole transport layer is formed on the substrate surface in the pixel area by discharging the liquid material containing the functional material to be the hole transport layer into the pixel area and removing the solvent from the liquid material by drying and heating. Is done. Next, a liquid material containing a functional material to be a light emitting layer is discharged onto the hole transport layer. At this time, on the surface of the hole transport layer, the liquid material for forming the light emitting layer is discharged. When the new liquid property of the hole transport layer is insufficient, or when the surface tension of the liquid droplet that becomes the light emitting layer is high, the light emitting layer cannot completely coat the anode or the hole transport layer depending on the shape of the partition wall. Sometimes.

  As described above, when a defect in the light emitting layer appears on the substrate surface in the pixel region, the anode or hole transport layer and the cathode or electron transport layer formed so as to sandwich the light emitting layer are short-circuited. Will do.

  When this short circuit occurs, when a current is passed through the organic EL element to obtain light emission, the light emitting layer becomes defective in light emission, in other words, a pixel having a short circuit becomes a black spot. In addition, a decrease in luminance due to current loss, heat generation due to leakage current, and an increase in power consumption occur, causing serious problems in power efficiency and device life.

  Next, as a further problem of the ink jet system, there is uneven thickness of the light emitting layer. The occurrence of this thickness unevenness will be described below.

  First, in the inkjet method, it is common to scan a plurality of pixel regions with an inkjet head and sequentially fill a liquid material for forming a light emitting layer for each pixel region. At this time, there is a difference in the holding time from the filling of the liquid material to the drying and heating for each pixel region. For example, when the liquid material filling operation time for all the pixel regions on the substrate is 30 seconds, the pixel region filled with the liquid material first is 30 pixels as compared with the pixel region filled with the liquid material last. A difference in holding time of seconds occurs. Due to the difference in holding time of 30 seconds, a part of the solvent continues to volatilize at normal temperature in the pixel region filled with the liquid material first. Also, the volatilization rate at room temperature varies depending on whether or not the liquid material is filled in adjacent pixels.

  As described above, the solvent volatilization state in each pixel region varies depending on the difference in holding time and the liquid material filling state of adjacent pixels, thereby causing uneven drying, resulting in uneven thickness of the light emitting layer. appear.

  In addition, when filling a liquid material for forming a light emitting layer in one pixel region, when discharging a plurality of droplets forming the light emitting layer, in order to improve the wettability of the droplets, In general, droplets are discharged to different positions. At this time, in one pixel region, the landing timing of the droplet on the surface of the pixel region varies depending on the difference in the discharge timing and the discharge speed of the droplet. At this time, in one pixel region, the first landed droplet spreads in a substantially circular shape around the landed position, but the next landed droplet depends on the surface tension of the landed droplet. Then, it will be drawn into the droplet landed first. As a result, the surface of the liquid material in the pixel region becomes uneven due to the landing order, and unevenness in the thickness of the light emitting layer or loss of the light emitting layer occurs in one pixel region.

  As described above, when the thickness unevenness or the defect of the light emitting layer occurs, luminance unevenness or light emission failure occurs in each pixel, and the display quality of the organic EL display device is deteriorated.

In order to improve the thickness unevenness and defects of the light emitting layer as described above, Patent Document 3 discloses a solvent capable of dissolving the functional material constituting the light emitting layer after forming the light emitting layer using an ink jet method. A method for producing an organic EL device is disclosed in which spraying is performed to flatten a light emitting layer.
JP 2000-106278 A (published on December 19, 1985) JP 2006-162881 A (released on June 22, 2006) JP 2003-142261 A (published May 9, 2002)

  However, in the manufacturing method disclosed in Patent Document 3, there is a large possibility of promoting a luminescent color defect due to color mixture of a liquid material containing a luminescent material in adjacent pixel regions, and there are many points that are difficult in practical use. .

  As a method for solving the defect of the light emitting layer, in order to completely cover the hole transport layer with the light emitting layer, it may be possible to increase the amount of the liquid material to be the light emitting layer. When the material is discharged into the pixel region, the liquid material leaks over the partition wall and leaks into the adjacent pixel region, or exceeds the desired thickness of the light emitting layer.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent a light emission color defect due to a color mixture of light emitting materials between pixel regions, prevent a loss of a light emitting layer in a pixel region, and a pixel. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus for a high-quality organic electroluminescence display device in which unevenness in the thickness of a light emitting layer is reduced between regions and within a pixel region.

In order to solve the above problems, a method for manufacturing an organic electroluminescence display device according to the present invention is as follows.
A method for manufacturing an organic electroluminescence display device, wherein a light-emitting layer is formed by discharging a first solution containing a light-emitting material to a partition region partitioned by a partition on a substrate, the method comprising: A soluble solution coating step in which a second solution that is soluble and has a lower viscosity than the first solution is applied to the entire area of the partition area; and the partition area to which the second solution is applied And a luminescent solution discharging step of discharging the first solution.

  According to said structure, after a 2nd solution is apply | coated to the whole area of a division area in a soluble solution application | coating process, a 1st solution is discharged to a division area in a luminescent solution discharge process. Here, since the second solution is soluble in the first solution, the first solution and the second solution are mixed when the first solution is discharged to the partition region. Further, since the second solution is applied to the entire area of the partition area, the discharged first solution may be drawn into the surface tension of the already discharged first solution, or the liquid repellency of the partition wall. Without being influenced by the properties, the first solution is mixed with the second solution applied to the entire area of the partition, and the entire area of the partition is covered with a uniform thickness.

  Thus, after that, the solution in which the first and second solutions are mixed is heated and dried in the same manner as in a method for manufacturing a general organic electroluminescence display device (hereinafter abbreviated as an organic EL display device). By doing so, the light emitting layer is coated with a uniform thickness over the entire partition region.

  Furthermore, in the case of an organic EL display device having a plurality of partition regions, in the method for manufacturing an organic EL display device of the present invention, after the second solution is applied to the partition regions, the first solution containing a light emitting material is added. Since it is applied to the partitioned areas, it is possible to prevent a luminescent color defect due to a color mixture of the luminescent materials between the partitioned areas.

  As described above, the manufacturing method of the organic EL display device of the present invention prevents the emission color defect due to the color mixture of the luminescent material between the partition regions, prevents the loss of the light emitting layer in the partition regions, and Unevenness in thickness can be reduced. As a result, the method for producing an organic EL display device of the present invention has an effect that a high-quality organic EL display device can be produced.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
It is preferable that the substrate surface in the partition region is formed of a solidified product of an aqueous solution.

  By providing the above configuration, it is possible to suppress the elution of the substrate surface in the partition region by the first solution and the second solution, which are organic solvents, and to suppress the leakage current between the electrodes. There is an effect that a high organic EL display device can be manufactured.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
The main component of the second solution is a first organic solvent, and the first solution preferably contains the first organic solvent.

  With the above configuration, the miscibility between the second solution and the first solution is improved, and as a result, the first solution covers the entire partition region more uniformly. Thereby, the light emitting layer formed by heating and drying has an effect that the entire partition region can be coated more uniformly.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
The partition region is substantially rectangular, and when the first solution is discharged into the one partition region in the luminescent solution discharge step, from one short side of the partition region to the other short side. On the other hand, it is preferable to sequentially discharge the droplets of the first solution to a plurality of different positions in the partition region.

  With the above configuration, the droplets of the first solution are dispersed and discharged in a plurality of locations in one partition region. Thereby, the miscibility between the second solution applied in advance to the partition region and the first solution is increased, and the light emitting layer having a more uniform thickness can be formed.

  Furthermore, by providing the above configuration, even if the nozzle row that discharges the first solution is inclined with respect to the scanning direction that scans the partition region, the thickness of the light emitting layer in the pixel region is reduced. Since it can hold uniformly, it becomes possible to match the arrangement pitch of the pixel region and the arrangement pitch of the nozzles, and the manufacturing tact is improved.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
The first solution includes a first organic solvent that is a main component of the second solution, and a second organic solvent that is soluble in the first organic solvent, and the first organic solvent includes: It is preferable that the boiling point is 200 degrees or less, and the second organic solvent has a boiling point of 200 degrees or more and 300 degrees or less.

  According to said structure, the 1st solution contains the 2nd organic solvent of the boiling point different from the 1st organic solvent which is a main component of a 2nd solution. Thereby, the volatilization rate of the liquid in which the first solution and the second solution are mixed can be adjusted by adjusting the ratio between the first solution and the second solution filled in the partition region. it can. As a result, there is an effect that the uniformity of the thickness of the light emitting layer to be formed is improved for each partition region.

  Moreover, since the second solution has a low boiling point and good wettability with respect to the substrate surface in the partitioned region, the second solution can cover the entire partitioned region. As a result, the first solution mixed with the second solution also covers the entire partition region, thereby preventing defects in the light emitting layer formed by heating and drying.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
The organic electroluminescence display device includes a plurality of the partition regions, and in the soluble solution coating step, the amount of the second solution to be discharged is preferably adjusted for each partition region.

  With the above configuration, the amount of the second solution to be filled can be changed for each partition region. As a result, even if there is a difference in the holding time from the filling of the first and second solutions to the drying and heating for each partition area, the amount of the second solution can be maintained by adjusting the amount of the second solution. It is possible to reduce drying unevenness due to the time difference. As a result, the unevenness of the thickness of the light emitting layer in each partition region is reduced, and an effect that a high-quality organic EL display device can be produced is achieved.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
In the soluble solution coating step, the second solution droplets are discharged to the partition region, and the second solution is discharged to the partition region by controlling the number of droplets of the second solution. It is preferable to adjust the amount of the solution.

  By providing the above configuration, it is only necessary to adjust the number of droplets to be discharged when adjusting the amount of the second solution to be filled in the partition region. There is an effect that it can be controlled.

The method for producing an organic electroluminescence display device according to the present invention further comprises:
The first solution includes a first organic solvent that is a main component of the second solution and a second organic solvent, and the first organic solvent has a boiling point of 200 degrees or more and 300 degrees or less. It is preferable that the second organic solvent has a boiling point of 100 degrees or more and 200 degrees or less.

  According to said structure, the 1st solution contains the 2nd organic solvent of the boiling point different from the 1st organic solvent which is a main component of a 2nd solution. Thereby, the volatilization rate of the liquid in which the first solution and the second solution are mixed can be adjusted by adjusting the ratio between the first solution and the second solution filled in the partition region. it can. As a result, there is an effect that the uniformity of the thickness of the light emitting layer to be formed is improved for each partition region.

In order to solve the above problems, a manufacturing apparatus for an organic electroluminescence display device according to the present invention is provided.
An apparatus for manufacturing an organic electroluminescence display device, wherein a first solution containing a light emitting material is discharged onto a partition region partitioned by a partition on a substrate to form a light emitting layer, wherein the first region includes the first solution. A first inkjet head that discharges the second solution, and a second inkjet head that discharges a second solution that is soluble in the first solution and has a lower viscosity than the first solution to the partition region. An ink jet head, and after the second ink jet head discharges the second solution to the partition region, the first ink jet head discharges the first solution to the partition region. It is said.

  With the above configuration, after the second inkjet head ejects the second solution to the partitioned region, the first inkjet head ejects the first solution. Thereby, there exists an effect similar to the manufacturing method of the organic electroluminescent display apparatus which concerns on this invention.

The apparatus for manufacturing an organic electroluminescence display device according to the present invention further comprises:
An apparatus for manufacturing an organic electroluminescence display device having a plurality of partition regions, wherein the storage unit stores the number of droplets of the second solution ejected by the second inkjet head corresponding to each partition region. And control means for controlling the droplets ejected by the second inkjet head based on the number of droplets stored in the storage means.

  With the above configuration, the control unit controls the second inkjet head based on the number of droplets of the second solution to be ejected for each partition region stored in the storage unit, and for each partition region, The amount of the second solution to be filled can be adjusted.

  As a result, it is possible to reduce drying unevenness due to the difference in holding time from the filling of the first solution and the second solution to the drying and heating in each partitioned region, resulting in uneven drying. There is an effect that unevenness in the thickness of the light emitting layer can be reduced.

  As described above, the method for producing an organic electroluminescence display device of the present invention is configured to remove the second solution that is soluble in the first solution and has a lower viscosity than the first solution. A soluble solution application step for applying the first solution to the partition region where the second solution is applied by the soluble solution application step. It is out.

  As described above, the manufacturing apparatus of the organic electroluminescence display device of the present invention is soluble in the first ink jet head for discharging the first solution to the partition region, and in the first solution, and And a first inkjet head for discharging a second solution having a lower viscosity than the first solution to the partition region.

  Accordingly, it is possible to manufacture a high-quality organic electroluminescence display device that can prevent the light emitting layer from being lost in the pixel region and can reduce unevenness in the thickness of the light emitting layer between and within the pixel regions.

  Embodiments according to the present invention will be described below with reference to the drawings.

Embodiment 1
(Schematic configuration of inkjet apparatus 1)
First, with reference to FIGS. 2A and 2B, the configuration of the inkjet apparatus 1 (an organic electroluminescence display apparatus manufacturing apparatus) according to the first embodiment of the present invention will be described. FIG. 2A is a plan view illustrating a schematic configuration of the inkjet apparatus 1, and FIG. 2B is a side view illustrating the schematic configuration of the inkjet apparatus 1.

  First, the inkjet device 1 is a device that forms a light emitting layer by an inkjet method on a substrate 3 constituting an organic electroluminescence display device (hereinafter referred to as an organic EL display device). More specifically, an ink containing a light emitting material for forming a light emitting layer is ejected from the inkjet head group 2 to a pixel region (partition region) 30 partitioned by a bank 31 (partition wall) on the substrate 3. Is a device for forming

  As shown in FIGS. 2A and 2B, the inkjet apparatus 1 includes a base 10, a head gantry 11 including the inkjet head group 2, and the head gantry 11 in the direction A shown in FIG. A linear motor type slide mechanism 12 for sliding, a suction plate 13 for holding the substrate 3 by suction, and a linear motor type suction plate slide mechanism 14 for sliding the suction plate 13 in the direction B shown in FIG. It has.

(Basic operation of inkjet apparatus 1)
Next, the basic operation of the inkjet apparatus 1 will be described with reference to FIG.

  In the ink jet apparatus 1, the head gantry 11 is moved by the slide mechanism 12 in the X direction shown in FIG. 2A, in other words, from the left side to the right side in FIG. In accordance with the movement of the head gantry 11, the inkjet head group 2 ejects ink droplets onto the pixel region 30 on the substrate 3. Next, after the head gantry 11 moves from the right side to the left side in the drawing, the suction plate 13 is moved in the direction B shown in the drawing by the suction plate slide mechanism 14 and positioned at an arbitrary position. After the positioning of the suction disk 13 is completed, the head gantry 11 is moved from the right side to the left side shown in FIG. As the head gantry 11 moves, the inkjet head group 2 ejects ink droplets onto the pixel region 30 on the substrate. As described above, the inkjet device 1 repeatedly performs the movement of the head gantry 11, the ejection of ink from the inkjet head group 2, and the movement of the suction plate 13, so that all the pixel regions 30 on the substrate 3 are moved. Thus, ink for forming the light emitting layer is discharged.

(Schematic configuration of inkjet head group 2)
Next, the configuration of the inkjet head group 2 will be described with reference to FIG.

  As shown in FIG. 2A, the inkjet head group 2 includes a plurality of light emitting elements for discharging a light emitting layer ink (first solution) containing a light emitting material for forming a light emitting layer to the pixel region 30. A layer inkjet head 21 (first inkjet head), and a solvent inkjet head 20 (second inkjet head) that ejects a solvent ink (second solution) soluble in the light emitting layer ink. Yes.

  In the solvent inkjet head 20, a plurality of nozzle holes 200 are arranged in series along the direction B in FIG. Further, the solvent inkjet heads 20 are staggered in the B direction as shown in FIG. Thus, the solvent inkjet head 20 can eject solvent ink droplets onto an arbitrary pixel region 30 in the Y direction of the substrate 3.

  On the other hand, the light emitting layer inkjet head 21 includes a blue inkjet head 21A that ejects a light emitting layer ink that forms a blue light emitting layer, and a green inkjet head 21B that ejects a light emitting layer ink that forms a green light emitting layer. And a red inkjet head 21 </ b> C that ejects light emitting layer ink for forming a red light emitting layer. In addition, the blue inkjet head 21A, the green inkjet head 21B, and the red inkjet head 21C have an inclination in the Y direction and are perpendicular to the Y direction, as shown in FIG. The direction is arranged in parallel along the X direction. Furthermore, each light emitting layer ink-jet head 21 includes a plurality of nozzle holes 210 arranged in series along its own inclination.

  Here, as the inkjet head 21 for the light emitting layer and the inkjet head 20 for the solvent, it is possible to use a known inkjet head such as a piezoelectric deformation method or a bubble jet (registered trademark) method. The inkjet device 1 includes a maintenance mechanism portion of an inkjet head (not shown). For example, the nozzle hole of the inkjet head, the wipe mechanism that faces the nozzle, and the cap mechanism that closes the nozzle hole when the device is not operating. In addition, a system using a known technique such as a non-discharge detection mechanism for checking the presence / absence of non-discharge for each nozzle hole (does not fly even if a command for discharging droplets is given) is mounted.

(Detailed configuration of inkjet head group 2)
Next, a detailed configuration of the inkjet head group 2 will be described below with reference to FIG. FIG. 3 is an explanatory diagram showing a detailed configuration of the pixel region 30 formed on the substrate 3 and the inkjet head group 2.

  In FIG. 3, a light emitting layer ink jet head 21 is filled with a light emitting layer ink containing a light emitting material for forming a light emitting layer, and the solvent ink jet head 20 is made of a solvent soluble in the light emitting layer ink. A solvent ink is filled. More specifically, the blue ink-jet head 21A has a light-emitting layer ink that forms a blue light-emitting layer (hereinafter referred to as blue light-emitting layer ink), and the green ink-jet head 21B has a green light-emitting layer that emits light. The layer ink (hereinafter referred to as green light emitting layer ink) and the red ink jet head 21C are filled with light emitting layer ink (hereinafter referred to as red light emitting layer ink) for forming a red light emitting layer, respectively. Yes. Specific examples of the light emitting layer ink and the solvent ink will be described later.

(Ink ejection operation to the pixel region 30)
Further, with reference to FIG. 3, an ink ejection operation from the inkjet head group 2 to the pixel region 30 will be described.

  First, as a first step (soluble solution coating step), the ink jet device 1 uses a solvent ink jet head 20 to form a solvent for the pixel regions 30A to 30F partitioned on the substrate 3 by banks. Discharge ink for filling. Next, as a second step (a luminescent solution discharge step), the inkjet device 1 uses the blue inkjet head 21A to the pixel regions 30A and 30D filled with the solvent ink, and uses the blue emission layer ink. The pixel regions 30B and 30E filled with the solvent ink are ejected using the green inkjet head 21B, and the pixel regions 30C and 30F filled with the solvent ink are ejected using the green inkjet head 21B. On the other hand, the red light emitting layer ink is ejected using the red inkjet head 21C. Thus, each pixel region 30 is filled with the corresponding color light emitting layer ink.

  More specifically, as the head gantry 11 (see FIG. 2A) moves in the X direction, the inkjet head group 2 also moves at a constant speed in the X direction. Then, when the three nozzle holes 200A to 200C of the solvent inkjet head 20 reach just above the pixel region 30A, droplets of solvent ink are ejected from the nozzle holes 200A to 200C. Further, the nozzle holes 200A to 200C eject droplets of solvent ink to the pixel regions 30B to 30F as in the case of the pixel region 30A.

  A plurality of solvent inkjet heads 20 are provided over the entire width in the Y direction of the substrate 3 (see FIG. 2A), and each of the plurality of pixel regions 30 connected in the Y direction of the substrate 3 is provided. The nozzle holes 200 are allocated and the solvent ink can be applied all at once. For example, the pixel regions 30 are regularly arranged at a pitch of 240 μm with respect to the Y direction, and the nozzle holes are regularly arranged at a pitch of 80 μm. In addition, since the solvent inkjet head 20 ejects a solvent having a low viscosity, the solvent ink wets and spreads over the entire area of one pixel region 30 even if the landing interval in the pixel region 30 is not so narrow. Therefore, the nozzle hole 200 is arranged in a direction orthogonal to the X direction that is the scanning direction of the solvent inkjet head 20, and further, the number of pixel regions that one solvent inkjet head 20 is responsible for is increased. It is possible to reduce the number of the inkjet heads 20 for the solvent.

  Next, each of the nozzle holes 211 </ b> A to 215 </ b> A included in the blue inkjet head 21 </ b> A sequentially reaches directly above the pixel region 30 </ b> A with a delay from the solvent inkjet head 20. At this time, the nozzle holes 211A to 215A eject droplets of the blue light emitting layer ink to the pixel region 30A filled with the solvent ink by the solvent inkjet head 20. Similarly, droplets of blue light emitting layer ink are also ejected from the nozzle holes 211A to 215A to the pixel region 30D filled with the solvent ink. The nozzle holes 211A to 215A do not eject the blue light emitting layer ink even if they reach the pixel regions 30B, 30C, 30E, and 30F.

  Next, each of the nozzle holes 211B to 215B provided in the green inkjet head 21B causes the droplets of the green light emitting layer ink to drop into the pixel area when the nozzle holes 211B to 215B sequentially reach directly above the pixel area 30B filled with the solvent ink. Discharge to 30B. Similarly, droplets of green light emitting layer ink are ejected to the pixel region 30E filled with solvent ink through the nozzle holes 211B to 215B. In this case as well, even if the nozzle holes 211B to 215B reach directly above the pixel regions 30A, 30C, 30D, and 30F, the green light emitting layer ink is not ejected.

  Further, each of the nozzle holes 211C to 215C included in the red inkjet head 21C sequentially reaches the pixel region 30C filled with the solvent ink, and then drops the red light emitting layer ink droplets into the pixel region 30C. To discharge. Similarly, ink droplets for red light emitting layer are ejected to the pixel region 30F filled with solvent ink through the nozzle holes 211C to 215C. In this case as well, the nozzle holes 211C to 215C do not eject the ink for the red light emitting layer even if the nozzle holes 211C to 215C reach directly above the pixel regions 30A, 30B, 30D, and 30E.

  As shown in FIG. 2A, a plurality of light emitting layer inkjet heads 21 are arranged in the Y direction shown in FIG. 2, and the nozzle holes provided in the light emitting layer inkjet head 21 are the same as described above. By the operation, the corresponding light emitting layer ink is ejected to each of the pixel regions 30. Here, as described above, in order to allocate five nozzle holes to one pixel region 30, the pixel regions 30 are arranged at a pitch of 240 μm with respect to the Y direction, and the nozzle holes are arranged in series at a pitch of 80 μm. In the case of regular arrangement, each of the inkjet heads 21 for light emitting layers may be inclined by about 64.5 degrees with respect to the Y direction.

  In this way, the arrangement of the nozzle holes, in other words, the longitudinal direction of each of the light emitting layer inkjet heads 21 is inclined with respect to the arrangement in the Y direction of the pixel region 30 in a state where the substrate 3 is viewed in plan view. As a result, the arrangement pitch of the pixel regions 30 and the integer multiple of the arrangement pitch of the nozzle holes can be matched. Further, as shown in FIG. 3, the liquid of the light emitting layer ink is shifted with respect to the pixel region 30 </ b> A by shifting the position with respect to the X direction as in the plurality of nozzle holes 211 </ b> A to 215 </ b> A that handle one pixel region 30 </ b> A. When the droplets are ejected, the droplets land with a time difference in the order of 211A, 212A, 213A, 214A, and 215A.

(Schematic process of forming the light emitting layer 56)
Next, with reference to FIGS. 4A to 4D, a process of forming the light emitting layer 56 in the pixel region 30 will be described. 4A to 4D are schematic views showing a cross section of the substrate 3 for explaining a process in which the light emitting layer 56 is formed. 4A to 4D show cross sections taken along the line CC 'in FIG.

  First, FIG. 4A shows a state before the solvent 41 that is the solvent ink is filled in the pixel regions 30A to 30F partitioned by the plurality of banks 31 on the substrate 3. FIG. Next, as illustrated in FIG. 4B, the light emitting layer inkjet head 20 fills all the pixel regions 30 </ b> A to 30 </ b> F with a solvent 41 that is a solvent ink. As will be described later, the solvent 41 has a low viscosity and uses a liquid that easily spreads throughout the pixel region 30. In the first step, the solvent 41 is a single pixel region 30. Spreads all over the inside.

  Next, after the solvent inkjet head 20 has applied the solvent 41 to the entire area of each of the pixel regions 30A to 30F, the light emitting layer inkjet head 21 ejects the light emitting layer ink to the pixel regions 30A to 30F. As a result, as shown in FIG. 4C, a liquid reservoir 42 in which the light emitting layer ink and the solvent 41 are mixed is formed in each of the pixel regions 30A to 30F.

  Next, as shown in FIG. 4D, a drying and curing device (not shown) volatilizes and solidifies unnecessary solvent components in the liquid reservoir 42, so that each of the pixel regions 30A to 30F is A light emitting layer 43 is formed. In addition, the light emitting layer 43A shown in the figure is a blue light emitting layer, the light emitting layer 43B is a green light emitting layer, and the light emitting layer 43C is a red light emitting layer.

  As described above, the drying unevenness between the pixel regions 30 can be improved by filling the entire area of the pixel region 30 with the solvent 42 in the first step and then filling the ink for the light emitting layer in the second step. The solvent ink that is the solvent 42 may be any solvent that is soluble in the light-emitting layer ink containing the light-emitting material, and in particular, when the light-emitting layer ink is a mixture of a plurality of organic solvents, An organic solvent having a low boiling point is used as a solvent ink. Thereby, the miscibility of the ink for the light emitting layer and the ink for the solvent is increased, and a light emitting layer having a more uniform thickness and no defect can be formed.

  In addition, it is preferable that the above-mentioned solvent ink does not contain a component that becomes a light emitting layer, in other words, a light emitting material. As a reason, in general, when the light emitting material is not added, the viscosity of the organic solvent becomes lower and the wettability of the organic solvent is further improved. That is, the ejected solvent ink has improved wettability in the partition region, and as a result, a light emitting layer having a more uniform thickness and no defects can be formed.

(Material of functional material layer)
Below, the material of each layer which comprises the functional material layer formed in the pixel area | region 30 on the board | substrate 3 based on this embodiment is demonstrated.

  First, the structure of the organic EL element provided in the organic EL display device manufactured in the present embodiment will be described. In the organic EL element, a plurality of thin film transistors and signal lines are formed on a substrate 3 (see FIG. 4A), and a planarization layer and a first electrode are formed above the surface side on which the thin film transistors and signal lines are formed. By the ink jet method formed on the formed active matrix substrate or on the passive matrix substrate on which the plurality of signal lines and the first electrode are formed on the substrate 3, and on the active matrix substrate or the passive matrix substrate. An insulating partition (bank) for holding the applied ink, and a functional material layer including at least an organic compound carrier transporting layer and a light emitting layer formed on the active matrix substrate or the passive matrix substrate; The second electrode is formed on the functional material layer.

  The active element portion such as TFT on the active matrix substrate and the organic EL portion are separated by an interlayer insulating film having a function of a planarizing layer, and the contact hole is filled through the contact hole formed in the interlayer insulating film. The lower active element portion and the upper first electrode are connected to each other through a conductive material. It is also possible to use the first electrode of the organic EL element as the connecting conductor.

The functional material layer including the carrier transport layer and the light emitting layer described above may be a low molecular material or a high molecular material. Further, as a layer constituting the functional material layer, the following layer configurations (1) to (7) ). The carrier transport layer refers to a hole transport layer or an electron transport layer. Furthermore, the electron blocking layer is one of the carrier blocking layers. In the present invention, the layers formed between the first electrode and the second electrode listed in the following (1) to (7) are collectively referred to as a functional material layer.
Layer structure (1): Organic light emitting layer (light emitting layer)
Layer structure (2): hole transport layer / organic light emitting layer (light emitting layer)
Layer structure (3): Organic light emitting layer (light emitting layer) / electron transport layer layer structure (4): Hole transport layer / organic light emitting layer (light emitting layer) / electron transport layer layer structure (5): Hole injection layer / Hole transport layer / organic light emitting layer (light emitting layer) / electron transport layer layer configuration (6): hole transport layer / electron blocking layer / organic light emitting layer (light emitting layer) / electron transport layer layer configuration (7): hole Transport layer / electron blocking layer / organic light emitting layer (light emitting layer) / electron transport layer / electron injection layer.

  4A to 4D, the configuration of (1) has been described for the sake of simplicity. The organic light emitting layer may be a single layer or a multilayer structure. Moreover, the layer which doped the base material with the dopant may be sufficient.

  Hereinafter, an organic EL element using a polymer organic light-emitting layer as a light-emitting layer will be described as this embodiment, but the present invention is not limited to this, and a low-molecular organic light-emitting layer is used as a light-emitting layer. It may be a thing.

(Ink material)
The organic light emitting layer ink which is the light emitting layer ink in the present embodiment is a solution containing at least a light emitting material, and may contain one kind or a plurality of kinds of light emitting materials. In addition, a film holding material (binder), a leveling material, a light emission assist material, an additive material (donor, acceptor, etc.), a carrier transport material, a light emitting dopant, and the like may be contained.

(Light emitting layer material)
As the light emitting material contained in the light emitting layer ink in the present embodiment, known light emitting materials for organic LED elements can be used. Such light emitting materials are classified into polymer light emitting materials, precursors of polymer light emitting materials, and the like. Examples of these specific compounds are shown below, but the present invention is not limited thereto.

  Examples of the polymer light-emitting material that is a light-emitting material include poly (2-decyloxy-1,4-phenylene) (DO-PPP), poly [2,5-bis- [2- (N, N, N-triethyl). Ammonium) ethoxy] -1,4-phenyl-alt-1,4-phenylene] dibromide (PPP-NEt3 +), poly [2- (2′-ethylhexyloxy) -5-methoxy-1,4-phenylenevinylene] (MEH-PPV) etc. are mentioned.

  Examples of the precursor of the polymer light emitting material include a poly (p-phenylene vinylene) precursor (Pre-PPV), a poly (p-naphthalene vinylene) precursor (Pre-PNV), and the like.

(Solvent material)
Next, the solvent in the present embodiment is a solvent that can dissolve or disperse the light emitting material, such as pure water, methanol, ethanol, THF (tetrahydrofuran), chloroform, toluene, xylene, trimethylbenzene, and the like.

(Material for carrier transport layer)
When the organic EL device produced by the present invention includes a hole transport layer and an electron transport layer (collectively referred to as a carrier transport layer), each of the hole transport layer and the electron transport layer has a single layer structure or Either a multilayer structure may be used, and each of the hole transport layer and the electron transport layer may also serve as a hole injection layer or an electron injection layer. Note that the carrier transport layer may be formed not only by the ink jet method but also by other known methods, similarly to the light emitting layer.

  Furthermore, a known material can be used as a material for forming the carrier transport layer. Although these specific compounds are shown below, this invention is not limited to this.

  First, as a material for forming the hole transport layer, for example, a porphyrin compound, N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), N, Aromatic tertiary amine compounds such as N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine (NPD), low molecular materials such as hydrazone compounds, quinacridone compounds, stilamine compounds, polyaniline, 3 , 4-Polyethylenedioxythiophene / polystyrene sulfonate (PEDOT / PSS), poly (triphenylamine derivatives), polyvinylcarbazole (PVCz) and other polymer materials, poly (p-phenylene vinylene) precursors, poly (p -Naphthalene vinylene) precursors such as polymer materials.

  Examples of the material for forming the electron transport layer include low-molecular materials such as oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, and fluorene derivatives, and polymer materials such as poly [oxadiazole]. .

(Material for carrier blocking layer)
When the organic EL device produced by the present invention includes a carrier blocking layer, the carrier blocking layer may have either a single layer structure or a multilayer structure. Note that the carrier blocking layer may be formed not only by the ink jet method but also by other known methods, similarly to the light emitting layer.

  A known material can be used as a material for forming the carrier blocking layer. Although these specific compounds are shown below, this invention is not limited to this.

  First, as a material for forming an electron blocking layer, a low molecular material such as N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), polyvinylcarbazole (PVCz ) And the like. Examples of the material for forming the hole blocking layer include polymer materials such as oxadiazole derivatives.

  In addition, as a solvent, the solvent used for formation of a light emitting layer can be used. However, for example, when the light emitting layer is laminated on the hole transport layer by the ink jet method, the hole transport material soluble in the solvent used for the light emitting material is dissolved in the solvent of the light emitting material at the time of forming the light emitting layer. Uniformity deteriorates.

  Therefore, it is desirable to use a material that is insoluble in the solvent used for the functional material laminated in the subsequent stage as the functional material in the previous stage, but the light emitting material is uniformly spread on the hole transport layer. A new problem arises, and one of the present invention solves this problem.

(Electrode material)
A well-known electrode material can be used for the 1st and 2nd electrode in the organic EL element manufactured by this invention. Note that a film such as a carrier injection layer (a hole injection layer and an electron injection layer) may be inserted on the interface between the electrode and the functional material as necessary.

  Here, materials and configurations of the anode as the first electrode and the cathode as the second electrode will be described below.

  First, as the anode, a metal material having a large work function (Au, Ni, Pt, etc.) or a conductive metal oxide (ITO, IZO, ZnO, SnO2, etc.) is used as a single layer or a laminated film of a plurality of materials. it can. Alternatively, an oxide having a thickness that does not significantly hinder the conductivity (for example, about 1 nm) stacked on the side in contact with the functional material layer may be used.

  On the other hand, as the electrode material used as the cathode, Ca, Ce, Cs, Rb, Sr, Ba, Mg, Li, or the like having a low work function of 4.0 eV or less can be used. Ca and Ba are preferably used for the light emitting layer. The cathode is made of a relatively scientifically stable metal such as Ni, Os, Pt, Pd, Al, Au, Rh, Ag, etc., in order to suppress the deterioration of the low work function electrode due to oxygen, water, etc. An alloy or a laminated structure is preferably used.

  Further, in the top emission type organic EL, the above-mentioned cathode needs to be formed thin in order to provide translucency, so that ITO, IZO, ZnO, SnO2, etc. are used in order to ensure sufficient conductivity as an electrode. The conductive metal oxide can be formed on a light-transmitting metal layer as a transparent electrode layer. The transparent electrode layer may be a single layer or a laminated film of a plurality of materials.

  The organic EL device manufactured by the present invention only needs to include at least a first electrode, an organic layer including at least a light-emitting layer, and a second electrode. For example, as in the oxide layer described above, The first electrode, a single layer or a plurality of functional material layers including at least a light emitting layer, and a layer other than the second electrode may be included.

(Specific examples of functional material layers)
Next, referring to FIGS. 1A to 1F, a specific example of a functional material layer formed in the pixel region 30 on the substrate 3 and a formation process of the light emitting layer 56 according to the present embodiment. Will be explained. FIGS. 1A to 1F are schematic views showing a cross section of the substrate 3 in which the pixel region 30 is enlarged for explaining a process in which the light emitting layer 56 is formed. 1A to 1F show cross sections of the pixel region 30 along the line DD ′ shown in FIG. In addition, the organic EL element produced by the manufacturing process of Fig.1 (a)-(f) is provided with a positive hole transport layer and a light emitting layer as a functional material layer formed between an anode and a cathode. is there. Needless to say, the present invention is not limited to this, and can also be applied to an organic EL element having a layer other than the hole transport layer and the light emitting layer as the functional material layer.

  A substrate 3 shown in FIG. 1A is a glass substrate on which thin film transistors made of an amorphous silicon film or a polycrystalline silicon film (not shown) are arranged in a matrix. Further, an ITO film is formed to a thickness of 100 nm by a sputtering method, and the ITO film is patterned by using a ferric chloride aqueous solution as an etching solution by using a photolithography technique, and a pixel region partitioned by the bank 31 An anode 300 is formed on 30 substrates 3.

  The anode 300 divided for each pixel region 30 is separated from the substrate 3 by an interlayer insulating film having a function of a thin film transistor and a flattening layer (not shown), and through a contact hole formed in the interlayer insulating film, Each is connected to a thin film transistor formed in a matrix. Further, a photosensitive acrylic resin is applied to the surface of the substrate 3 including the anode 300 by a spin coating method so as to have a thickness of approximately 2 μm, and exposure and development are performed. To form a matrix-like pixel pattern as shown in FIG.

The length of the pixel region 30 surrounded by the bank 31 in its own longitudinal direction, in other words, the Y direction shown in FIG. 3 is 220 μm, and the pitch P between adjacent pixels is 240 μm. The width of the pixel region in the short direction is 70 μm, and both ends in the long direction are semicircular with a radius of 35 μm. The area of one pixel region is about 14300 (μm ² ).

  First, as shown in FIG. 1A, another device different from the ink jet device 1 (see FIG. 2) directs an underlayer droplet 50 containing a material for forming a hole transport layer toward the pixel 30. Dripping and spreading on the anode 300. The underlayer droplet 50 uses PEDOT / PSS (a mixture of polyethylene dioxythiophene and polyethylene sulfonic acid) as a material for forming the hole transport layer, and water as a solvent for dispersing or dissolving the PEDOT / PSS. The PEDOT / PSS aqueous solution prepared by using was used. Here, the PEDOT / PSS aqueous solution is prepared to have a viscosity of about 8 cp and a surface tension of about 30 dyn / cm. The operation of filling three droplets of the foundation layer droplet per pixel with a droplet amount of 6 pl per droplet is performed for all the pixel regions 30 on the substrate 3. Thereafter, the substrate 3 is left in a vacuum dryer (not shown) at room temperature and 1 Torr for 20 minutes to dry and remove water, which is a solvent component of the underlayer droplet 50, and then heated to 200 ° C. on a hot plate. Bake for 5 minutes. Thereby, a base layer 51 as a hole transport layer as shown in FIG. 4B is formed on the substrate 3 in the pixel region 30.

  Next, the light emitting layer ink and the solvent ink will be described. In this embodiment, a polyfluorene-based light-emitting material is used as a material for forming a light-emitting layer included in the light-emitting layer ink, and an aromatic mixed solvent is used as a solvent.

Note that there is an empirical rule of the following formula (1) between the vapor pressure vp {Pa} (25 ° C.) and the boiling point bp {° C.} of the solvent, and the lower the boiling point, the higher the vapor pressure of the solvent. There is. For example, the vapor pressure at 25 ° C. of a solvent having a boiling point of 160 ° C. can be estimated to be about 340 Pa, about 60 Pa at a boiling point of 200 ° C., and about 1 Pa at a boiling point of 300 ° C.
Vp = 278276e−0.0419 bp (1)
Here, when the mixed solvent used for the light emitting layer ink is specifically described, the following mixture of the first organic solvent and the second organic solvent is preferable.

  As the first organic solvent, for example, 1,2,4-trimethylbenzene (boiling point: 168 ° C.), 1,3,5-trimethylbenzene (165 ° C.), cumene (152 ° C.) having a boiling point of 200 ° C. or less. , Anisole (156 ° C.), xylene (140 ° C.) alone, or a mixture thereof.

  Next, as the second organic solvent, for example, 1,3,5-triethylbenzene (boiling point under atmospheric pressure; 215 ° C.) having a boiling point of 200 ° C. or higher and 300 ° C. or lower, tetralin (49.1 Pa, 207 ° C.), planariten (48.1 Pa, 205 ° C.), cyclohexylbenzene (240.1 ° C.), diisopropylbenzene (33.3 Pa, 204-207 ° C.), diphenylmethane (1.07 Pa, 265 ° C.), diphenyl ether ( 3.00 Pa, 259 ° C.), ethyl phenyl sulfide (204-205 ° C.), phenyl sulfide (1.01 Pa, 295 ° C.) alone or a mixture.

  Hereinafter, some examples of the combination of the light emitting layer ink and the solvent ink suitable for the present invention will be described.

  First, as a first combination example, the light emitting layer ink has a light emitting material composed of 20% 1,3,5-trimethylbenzene belonging to the first organic solvent and cyclohexylbenzene belonging to the second organic solvent. What was prepared by dissolving in a mixed solvent of 80% is used. The ink for the light emitting layer to be used is adjusted so that 7 to 10 mg of the light emitting material is dissolved per 1 ml of the mixed solvent. At this time, the viscosity is 15 to 17 cp and the surface tension is about 40 dyn / cm.

Further, the solvent ink is a mixed solvent of 90% 1,3,5-trimethylbenzene belonging to the first organic solvent and 10% cyclohexylbenzene belonging to the second organic solvent, and the viscosity at this time Is 2 to 4 cp. (Combination A)
As a second combination example, 1,3,5-trimethylbenzene is used as the first organic solvent, and phenyl sulfide is used as the second organic solvent, and the light emitting layer is formed with the same mixing ratio as the above combination A. You may use what made the ink for solvent, and the ink for solvent. (Combination B)
Further, as a third combination example, the light emitting layer ink is prepared by dissolving the light emitting material with 100% diphenylmethane belonging to the second organic solvent, and the solvent ink belongs to the first organic solvent. You may use what made xylene 100%. (Combination C)
Even if any combination of the above combination A, combination B, and combination C is used, a favorable light emitting layer can be formed in the manufacturing method according to the present invention.

  The ink for solvent preferably contains an organic solvent having a boiling point of 200 ° C. or lower, and the ink for light emitting layer preferably contains an organic solvent having a boiling point of 200 ° C. or higher and 300 ° C. or lower.

  Further, the solvent of the light emitting layer ink is a mixture of a second organic solvent having a boiling point of 200 ° C. or higher and 300 ° C. or lower and a first organic solvent having a boiling point of 200 ° C. or lower. It is preferable that the organic solvent is a main component.

  However, even if the light emitting layer ink and the solvent ink are produced only with the organic solvent belonging to the second organic solvent, the second light emitting layer ink is dissolved in the second light emitting layer ink. Since the ink for solvent consisting only of the organic solvent has a low viscosity, it has better wettability than the ink for the light emitting layer. Therefore, the effects of the present invention can be exhibited if various conditions are adjusted so that the solvent ink is spread throughout the pixel region 30.

  In addition, the combination A mentioned above shall be used for the combination of the light emitting layer ink and the solvent ink shown in FIGS.

  Next, with reference to FIGS. 1C to 1F, a process of forming a light emitting layer on the base layer 51, which is a hole transport layer formed on the substrate 3, will be described.

  As shown in FIG. 1C, the solvent droplet 52 (second solution) made of the solvent ink is a hole transport layer in the pixel region 30 by the solvent inkjet head 20 (see FIG. 3). The ink is discharged toward the base layer 51. At this time, the solvent inkjet head 20 uses three nozzle holes 200 (see FIG. 3) per pixel region 30 to eject one or two solvent droplets 52 per nozzle hole 200. A total of 5 solvent droplets 52 are landed on the underlayer 51. In the present embodiment, the solvent droplet 52 is 5 pl per droplet, and the solvent ink cannot cover the entire area of one pixel region 30 unless it is not less than 4 droplets per pixel region 30. It was. Note that the wetting and spreading property of the solvent ink with respect to the pixel region 30 includes the contact angle between the base layer 51 and the ejected solvent droplet 52, the surface tension of the solvent ink, the pixel size of the pixel region 30, and the solvent liquid. Since it differs depending on the size of the droplet 52, the number of solvent droplets 52 and the amount per droplet may be set as appropriate by conducting a preliminary experiment.

  Next, as shown in FIG. 1D, the solvent droplets 52 ejected by the solvent inkjet head 20 spread so as to cover the entire area of the underlying layer 51 in the pixel region 30, and the entire area of the underlying layer 51. A solvent pool 53 is formed to cover. In addition, it is preferable to perform the liquid repellency treatment on the bank 31 in advance before discharging the solvent droplet 52 to the pixel region 30. By performing this lyophobic treatment, it is possible to further prevent the light emitting layer ink droplets or the light emitting layer ink reservoir described later from leaking to the other adjacent pixel region 30 beyond the bank 31. .

  Further, as shown in FIG. 1D, the light-emitting layer inkjet head 21 applies the light-emitting layer droplets 54 (first solution) made of the light-emitting layer ink to the pixel region 30 in which the solvent reservoir 53 is formed. ) Is discharged. The light emitting layer droplets 54 are 4 pl per droplet, and the five nozzle holes 210 included in the light emitting layer inkjet head 21 per pixel area 30 are 2 droplets per nozzle hole 210, for a total of 10 light emitting layers. A droplet 54 is discharged. As described with reference to FIG. 2, the nozzle hole 210 that handles one pixel region 30 is a plan view of the substrate 3 with respect to the arrangement region of the pixel regions, in other words, the Y direction shown in FIG. 2. In the state, since it is inclined, as shown in FIG. 1D, the light emitting layer droplets 54 ejected from the nozzle holes 210 land on the solvent reservoir 53 with a time difference.

  Next, as shown in FIG. 1E, the light emitting layer droplets 54 are mixed with the solvent reservoir 53, and a light emitting layer ink reservoir 55 is formed over the entire area of the base layer 51 in the pixel region 30. A detailed description of the mixing of the light emitting layer droplet 54 and the solvent reservoir 53 will be given later.

Furthermore, the substrate 3 on which the light emitting layer ink reservoir 55 is formed in the pixel region 30 is dried for 60 minutes in a 200 ° C. environment on a hot plate in an N ₂ atmosphere (not shown). As a result, the solvent component in the light emitting layer ink reservoir 55 is removed by drying, and the light emitting layer 56 is formed on the base layer 51.

  Next, by laminating Ba and Al as the cathode 60 on the substrate 3 on which the hole transport layer and the light emitting layer are formed using a known technique, an organic EL as shown in FIG. A display device (organic EL element) is completed.

  In the organic EL display device manufactured by the procedure described with reference to FIGS. 1A to 1F, the light emitting layer 56 is completely covered with respect to the base layer 51 that is a hole transport layer. In addition, since the cathode 60 is formed on the light emitting layer 56, the base layer 51, which is a hole transport layer, and the cathode 60 do not come into contact with each other, and as a result, generation of leakage current is suppressed.

  In addition, when the produced organic EL display device includes an electron transport layer, the base layer 51 that is a hole transport layer and the electron transport layer are in contact with each other by using the manufacturing method of the present embodiment. Alternatively, the electron transport layer and the anode 300 are not in contact with each other, and the occurrence of leakage current is suppressed.

(Comparative Example 1)
Hereinafter, as a comparative example for the present embodiment, after forming the hole transport layer, a plurality of inks for forming the light emitting layer are sequentially ejected directly on the surface thereof, and a manufacturing method for forming the light emitting layer (conventional method) Will be described with reference to FIGS. FIGS. 5A to 5C are explanatory views showing an example of a light emitting layer forming process in the conventional method.

  First, as shown in FIG. 5A, a base layer 51 as a hole transport layer is formed by a known technique, and then light emitting layer droplets 54A, 54B, 54C, 54D, and 54E are sequentially formed on the pixels. Discharge toward the region 30. First, when the light emitting layer droplets 54A land on the base layer 51, when the substrate is viewed in plan, the base layer 51 wets and spreads in a substantially circular shape when viewed from the top surface of the substrate, and forms a landing pool 57A indicated by a dotted line. Form. Next, when the light emitting layer droplet 54B lands on the landing pool 57A where the light emitting layer droplet 54A wets and spreads on the base layer 51, a part of the light emitting layer droplet 54B is landed due to the surface tension of the landing pool 57A. The light emitting layer droplets 54B were attracted to the pool 57A side and did not spread sufficiently on the underlayer 51.

  Such a phenomenon occurs sequentially with respect to the light emitting layer droplets 54A, 54B, 54C, 54D, and 54E, and as shown in FIG. 5B, at the position of the light emitting layer droplet 54A landed first. Accordingly, the shape of the light emitting layer ink reservoir 55 becomes non-uniform, and as a result, the light emitting layer ink is not completely spread on the base layer 51. In this state, when the light emitting layer ink is dried and the cathode 60 is formed thereon, as shown in FIG. 5C, the base layer 51 as the hole transport layer and the cathode 60 are electrically short-circuited. As a result, a leak region 70 in which a leak current is generated due to a short circuit is formed. Even if the leak region 70 is not formed, the thickness of the light emitting layer is not uniform in the pixel region 30 and light emission unevenness occurs.

(Comparative Example 2)
Furthermore, as a further comparative example for the present embodiment, after forming a hole transport layer, a manufacturing method (conventional method) for forming a light emitting layer by simultaneously ejecting a plurality of inks for forming a light emitting layer directly on the surface thereof Will be described with reference to FIGS. 6A to 6C are explanatory views showing another example of the light emitting layer forming step in the conventional method.

  In Comparative Example 1, the case where the light emitting layer droplets 54A to 54E land on the underlayer 51 with a time difference has been described. However, in Comparative Example 2, the light emitting layer droplets 54A, 54B, 54C, 54D, A case will be described in which 54E lands on the base layer 51 almost simultaneously.

  First, as shown in FIG. 6A, when the light emitting layer droplets 54 </ b> A to 54 </ b> E land simultaneously on the underlayer 51, the light emitting layer droplets 54 </ b> A to 54 </ b> E are parallel to the surface of the underlayer 51. Before wetting and spreading, it is connected to other light emitting layer droplets adjacent on the underlayer 51. As a result, as shown in FIG. 6B, due to the surface tension of the landed light emitting layer ink, a light emitting layer ink reservoir 55 having a large raised center is formed. Furthermore, as shown in FIG. 4B, when the light emitting layer ink is dried on the base layer 51 which is a hole transport layer and the light emitting layer ink is dried without spreading completely, and the cathode 60 is formed thereon. As shown in FIG. 5C, the base layer 51, which is a hole transport layer, and the cathode 60 are electrically short-circuited, and a leak region 70 in which a leak current is generated due to the short-circuit is formed.

  In the organic EL display devices described in Comparative Examples 1 and 2, a light emitting layer is formed on the hole transport layer, and a cathode is further formed on the light emitting layer. The problems occurring in Comparative Examples 1 and 2 are not limited to the case where only the hole transport layer and the light emitting layer are provided as the functional material layer. Instead of the hole transport layer, the electron transport layer is formed on the light emitting layer. The same problem occurs when they are stacked. That is, since the electron transport layer has a lower resistance than the light emitting layer, the anode is not completely covered with the light emitting layer, and when there is a portion where the anode is exposed, the electron transport layer does not go through the light emitting layer. Direct contact with the anode. As a result, a decrease in luminance due to current loss in the portion, heat generation due to leakage current, and an increase in power consumption occur.

  Similarly, when both the hole transport layer and the electron transport layer are used as the functional material layer, similarly, the contact between the hole transport layer and the electron transport layer, the hole transport layer and the cathode are not interposed via the light emitting layer. The contact and the contact between the electron transport layer and the anode cause the above problem.

(Detailed formation process of light emitting layer 56)
Next, a detailed process from the landing of the light emitting layer droplet 54 on the underlayer 51 to the formation of the light emitting layer 56 in the first embodiment with respect to Comparative Example 1 and Comparative Example 2 is shown in FIG. ) To (c). FIGS. 7A to 7C are explanatory views showing a process of forming the light emitting layer 56 from the landing of the light emitting layer droplets 54 to the base layer 51.

  Compared to Comparative Examples 1 and 2 described above, in the method of manufacturing the organic EL display device according to the first embodiment, solvent droplets are ejected in advance before the light emitting layer droplet 54 is ejected to the pixel region 30. A solvent pool 53 is formed on the underlayer 51.

  As a result, as shown in FIG. 7A, when the light emitting layer droplets 54 land on the solvent reservoir 53, they mix at the landing position to form a light emitting layer ink reservoir 55. On the other hand, in the end portion in the pixel region 30, in other words, in the vicinity of the bank 31, only the solvent reservoir 53 is in the initial state when the light emitting layer droplets 54 land. Here, as time passes, the solvent in the solvent pool 53 having a low boiling point and a high vapor pressure is a central portion in the pixel region 30, in other words, the ink and the solvent pool for the light emitting layer, as indicated by the black arrows in FIG. Evaporates faster than the part where 53 is mixed.

  As a result, the light emitting layer ink reservoir 55 in the center is attempted to be drawn in by the diffusion action of the solvent. Further, the luminescent material diffuses in the liquid from the light emitting layer ink reservoir 55 toward the solvent reservoir 53 at the end portion. Due to the action of both, the luminescent material is transported in the liquid toward the direction of the white arrow in the figure, in other words, from the central portion to the end portion in the pixel region 30, and the end in the pixel region 30. It becomes possible to spread the light emitting material also in the part. When the light emitting layer ink reservoir 55 and the solvent reservoir 53 are mixed, the evaporation from the pixel region 30 becomes substantially constant as shown by the black arrow in FIG. In this state, when the light emitting layer ink reservoir 55 is dried, as shown in FIG. 7C, it is possible to form the light emitting layer 56 that uniformly covers the base layer 51 that is the hole transport layer.

  In particular, when the surface of the base layer 51 on which the light emitting layer droplets land is formed by curing an aqueous solution containing a solid content, the present invention has a remarkable effect. For example, using PEDOT / PSS (a mixture of polyethylene dioxythiophene and polyethylene sulfonic acid), a solid content such as a PEDOT / PSS aqueous solution prepared using water as a solvent for dispersing or dissolving the PEDOT / PSS. The hole transport layer is formed by drying an aqueous solution containing, and the ink for the light emitting layer composed of an organic solvent in which PEDOT / PSS is insoluble is deposited thereon.

  When the first organic solvent used in the solvent ink is a boiling point of 100 ° C. or less, for example, acetone, isopropyl alcohol, methyl ether ketone, methanol, etc., the volatilization rate is too high and good results are obtained. It may not be obtained. Further, as the first organic solvent, a solvent having a boiling point of 140 ° C. to 170 ° C. was particularly good.

(Drying unevenness between pixel areas)
Next, drying unevenness between pixels when the light emitting layer ink is applied to all the pixel regions 30 on the substrate will be described with reference to FIG. FIG. 8 shows a light emitting layer droplet 54 (see FIG. 1D) in a pixel region 40 arranged in a matrix by an ink jet apparatus that does not include the solvent ink jet head 20 (see FIG. 2), which is a conventional method. FIG. 6 is an explanatory diagram illustrating a state of each pixel region 40 when the liquid crystal is discharged. In addition, about the same member as the ink jet apparatus 1 (refer FIG. 2) which concerns on this embodiment here, the same member number is attached | subjected and the description is abbreviate | omitted.

First, as shown in FIG. 8, the inkjet head 21 for the light emitting layer scans in the direction of arrow F in the figure, and the pixel area 40 on the upper side of the drawing with respect to the broken line II ′ in the figure. Then, the ink for the light emitting layer is filled. Next, the inkjet heads 21A to 21C for the light emitting layer move in the direction of arrow G in the drawing, and then scan in the H direction in the drawing. In the process of scanning in the direction of arrow H, the light-emitting layer inkjet head 21 has a pixel area 40 (a pixel area in the area E in the figure) below the broken line II ′ in the figure. In contrast, the ink for the light emitting layer is filled. Here, the state of the pixel region 40 in the region E can be generally divided into the following five groups (1) to (5).
State (1): A pixel region 40A in which the pixel region 40 adjacent in the Y direction is the pixel region 40 that has already been filled with the light emitting layer ink in the F direction scan.
State (2): A pixel region 40B in which the light emitting layer ink is filled by the light emitting layer inkjet head 21A in a state where both of the pixel regions 40 adjacent in the X direction are not filled with the light emitting layer ink.
State (3): Pixel region 40C in which the light emitting layer ink-jet head 21B is filled with the light emitting layer ink in a state where only one of the pixel regions 40 adjacent in the X direction is filled with the light emitting layer ink.
State (4): Pixel region 40D in which the light emitting layer ink is filled by the light emitting layer inkjet head 21C in a state where both of the pixel regions 40 adjacent in the X direction are filled with the light emitting layer ink.
State (5): A pixel region 40E in which the light emitting layer ink is filled by the light emitting layer inkjet head 21 in a state where the pixel region 40 adjacent in the Y direction is not filled with the light emitting layer ink.

  Strictly speaking, the pixel region 40A and the pixel region 40E also have the same state as the pixel regions 40B, 40C, and 40D in the X direction.

  First, in the pixel region 40 filled with the light emitting layer ink by the light emitting layer ink jet heads 21A to 21C, it is included in the light emitting layer ink depending on whether or not the adjacent pixel region 40 is filled with the light emitting layer ink. The solvent volatilization rate differs. Specifically, in the pixel region 40 filled with the light emitting layer ink, the volatilization rate of its own light emitting layer ink becomes slower as the adjacent pixel region 40 is filled with the light emitting layer ink.

  Here, as shown in the above states (1) to (5), the pixel area 40 in which the ink-jet head 21 for the light-emitting layer is filled with the ink for the light-emitting layer depends on the position of the pixel area 40. The filling state is different, and as a result, the drying speeds of the pixel regions 40A to 40E are different. Thereby, drying unevenness occurs between the pixel regions 40A to 40E, and as a result, the thickness of the light emitting layer to be formed is multiplied.

  More specifically, the order of the pixel regions in which the entire light emitting layer tends to be formed tends to be the pixel region 40E, the pixel region 40B, the pixel region 40C, the pixel region 40D, and the pixel region 40A. Here, although the pixel region 40A and the pixel region 40E are adjacent to each other with respect to the Y direction, their dry states are greatly different, resulting in a difference in the thickness and light emission characteristics of the light emitting layer. A so-called stripe unevenness in which the joint portion is emphasized in a line shape is generated.

  In addition, since the light emitting layer inkjet head 21 for each color is provided with an offset in the scanning direction, the pixel area 40 adjacent to each color is filled as shown in the pixel areas 40B, 40C, and 40D. A difference arises and a difference arises in the thickness and the light emission characteristic of the light emitting layer for every color, As a result, the color reproducibility of an organic electroluminescence display device deteriorates.

  On the other hand, in Embodiment 1 according to the present invention, in addition to the light emitting layer inkjet head 21, the solvent inkjet head 20 (see FIG. 2) is mounted, and the substrate 3 ( Almost all the pixel regions 30 (see FIG. 2) on the top can be filled with solvent ink.

  Specifically, in the first scan, the solvent ink jet head 20 fills all the pixel regions 30 in the substrate 3 with the solvent ink, and then the light emitting layer ink jet heads 21A to 21C respectively The ink for the light emitting layer corresponding to the light emitting color is filled. As a result, the manufactured organic EL display device was able to obtain a good panel with little unevenness.

  In the conventional method, as described with reference to FIG. 5, when the nozzle rows are arranged to be inclined with respect to the scanning direction, a landing timing shift occurs in the pixel region, and a plurality of light emitting layer droplets are not aligned. There was a pull-in shape shift due to surface tension. And it became clear that this shape shift emphasizes the influence of the drying difference due to the influence of adjacent pixels, and increases and emphasizes the occurrence of uneven stripes. Therefore, particularly when the nozzle row is inclined with respect to the scanning direction, the solvent ink is first wetted and spread in the pixel area as in the present invention. As well as alleviating the above, the uniformity of the light emitting layer thickness in the pixel region is improved. Thereby, the unevenness in the organic EL display device, which was a problem of the conventional method for manufacturing the organic EL display device, can be remarkably improved. In Embodiment 1 of the present invention, the same result can be obtained even when the solvent ink is filled in all the pixel regions in the substrate during the first reciprocal scan of the first scan and the second scan. Obtained.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. The second embodiment described below is a modification of the first embodiment. Specifically, the ejection method for filling the pixel region 30 with the solvent ink is changed. In the following second embodiment, portions that are different from the above-described first embodiment will be described, and descriptions of overlapping portions will be omitted.

(Adjustment of solvent ink discharge rate)
As described in the first embodiment, the pixel region 30 is filled with the solvent ink and then filled with the light emitting layer ink, so that the pixel region 30 between the pixel regions 30 described with reference to FIG. Drying unevenness can be suppressed.

  Here, the closer the pixel region 30 is to the end of the substrate 3, and after the solvent inkjet head 20 fills the pixel region 30 with solvent ink, the light emitting layer inkjet head 21 removes the light emitting layer ink. The longer the time until ejection, and the longer the time from the mixing of the solvent ink and the light emitting layer ink to the drying step of the mixed light emitting layer ink reservoir 55, the longer the light emitting layer 56 formed. Tend to be thin.

  Accordingly, in order to further suppress drying unevenness between the pixel regions 30, in the second embodiment, the time from the ejection of the light emitting layer ink for each pixel region 30 to the drying process of the light emitting layer ink is determined on the substrate 3. The ejection amount of the solvent ink is adjusted in consideration of the arrangement position of each pixel region 30.

(Configuration of organic EL display panel manufacturing apparatus 70)
With reference to FIG. 9, the structure of the organic electroluminescent display panel manufacturing apparatus 70 in this Embodiment 2 is demonstrated below. FIG. 9 is a schematic diagram showing the configuration of the organic EL display panel manufacturing apparatus 70.

  As shown in the figure, the organic EL display panel manufacturing apparatus 70 further includes solvent droplets 52 (see FIG. 1C) ejected by the solvent inkjet head 20 relative to the inkjet apparatus 1 of the first embodiment. A droplet number control unit 8 (control means) for controlling the number of droplets and a control computer 9 connected to the droplet number control unit 8 are provided.

  Further, the droplet number control unit 8 includes a droplet number storage unit 81 (storage unit) that stores the number of solvent droplets 52 (see FIG. 1C) to be filled for each pixel region 30, and a droplet number storage unit 81. And a pattern determining unit 82 that determines a discharge pattern that is a discharge position of the solvent droplet 52 for each pixel region 30 based on the information from.

(Operation of the organic EL display panel manufacturing apparatus 70)
The control computer 9 stores arrangement information of the pixel regions 30 on the substrate 3 of the organic EL display panel included in the organic EL display device to be manufactured. Based on the arrangement information, the light emitting layer inkjet head 21 and the solvent are stored. The inkjet head 20 is selected. Specifically, the control computer 9 uses the size of the pixel region 30 on the substrate 3 and the information on the arrangement pitch, and the ink jet head 21 for the light emitting layer and the ink jet for the solvent that have the arrangement pitch of the corresponding nozzle holes. The head 20 is selected.

  First, when the droplet number control unit 8 receives an instruction from the control computer 9 to eject solvent ink onto the pixel region 30 on the substrate 3, the droplet number control unit 8 receives a pixel region from the droplet number storage unit 81. Read the number of drops every 30. Further, the pattern determination unit 82 determines the ejection pattern of the solvent droplets 52 for each pixel region 30 based on the read number of droplets for each pixel region 30.

  Next, the droplet number control unit 8 outputs the number of solvent droplets 52 and the discharge pattern information for each pixel region 30 to the inkjet device 1. As a result, the ink jet apparatus 1 operates the solvent ink jet head 20 based on the number of solvent droplets 52 and the discharge pattern information for each pixel region 30 input from the droplet number control unit 8.

  Hereinafter, adjustment of the ejection amount of the solvent ink will be described based on a specific example of the second embodiment.

〔Example〕
(Preliminary information generation)
First, in order to obtain information on the number of solvent droplets 52 for each pixel region 30 stored in the droplet number control unit 8 in advance, all the pixel regions 30 are formed by applying the same amount of solvent ink. In addition, a test organic EL display device is manufactured. Specifically, using the solvent inkjet head 20 with the solvent inkjet head 20 having an amount of 3 pl per solvent droplet 52, 8 droplets of solvent droplet 52 per pixel region 30 are obtained. It discharges to all the pixel areas 30. Next, as described in the first embodiment, the light emitting layer ink is ejected to the pixel region 30, and a test organic EL display panel capable of emitting light is manufactured through a drying process and an electrode forming process.

  Here, using a known CCD camera system, the luminance of each pixel area 30 in the test organic EL display panel area is measured, and each of the pixel areas 30 is classified into three luminance ranges. Divided. It is assumed that pixels belonging to the bright luminance range are luminance class A, pixels belonging to the intermediate luminance range are luminance class B, and pixels belonging to the dark luminance range are luminance class C.

  In this way, the luminance of each pixel region 30 is measured in advance, and the droplets of the solvent droplet 52 for each pixel region 30 stored by the droplet number control unit 81 based on the classification information of the luminance classes A to C. Ask for number information. In the present embodiment, the pixel region 30 corresponding to the luminance class A having high luminance has nine droplets of the solvent droplet 52, and the pixel region 30 corresponding to luminance class C having low luminance has the solvent liquid. The number of droplets 52 was 7 and the number of solvent droplets 52 was 8 in the pixel region 30 corresponding to the luminance class B having an intermediate luminance.

  Information on the luminance class for each pixel region 30 obtained using the test organic EL display panel is input to the droplet number storage unit 81 from the outside in advance.

  Here, with reference to FIGS. 10A and 10B, the relationship between the position of each pixel region and the luminance class in the organic EL display panel manufactured by the organic EL display panel manufacturing apparatus 70 will be described. FIG. 10A shows a part of the pixel region 30 arranged in a matrix on the substrate 3 of the organic EL display panel, and FIG. 10B shows each of the pixel regions 30 shown in FIG. 4 is an explanatory diagram showing a luminance class and the number of solvent droplets 52 to be filled in the pixel region 30. FIG.

  First, as shown in FIG. 10A, for the pixel regions 30 arranged in a matrix, the arrangement in the column direction is X1 to X6, and the arrangement in the row direction is Y1 to Y4. When the position of one pixel region 30 is indicated, in the following description, for example, the position of one pixel region 30 is indicated as a pixel region (X1, Y1).

  First, in the present embodiment, when the droplet number control unit 8 inputs an instruction to eject solvent ink from the control computer 9, the droplet number control unit 8 sets the luminance class for each position of the pixel region 30 as the droplet class. It is obtained by collating with the information stored in the number storage unit 81. For example, in FIG. 10B, the pixel region (X2, Y1) is the luminance class A, the pixel region (X2, Y2) is the luminance class B, and the pixel region (X2, Y3) is the luminance class C. Next, the droplet number control unit 8 outputs the acquired luminance class information for each pixel region 30 to the pattern determination unit 82.

  The pattern determination unit 82 that has input the luminance class information for each pixel region 30 determines the ejection pattern corresponding to the luminance class for each pixel region 30. Hereinafter, discharge patterns corresponding to the luminance classes A to C will be described with reference to FIGS. 11A is an explanatory diagram showing an ejection pattern corresponding to the luminance class A, FIG. 11B is an explanatory diagram showing an ejection pattern corresponding to the luminance class B, and FIG. FIG. 4 is an explanatory diagram showing a discharge pattern corresponding to a luminance class C.

  As shown in FIG. 11A, nine solvent droplets 52 are discharged to the nine discharge positions 60 surrounded by the broken line in FIG. As described above, the droplet number control unit 8 controls the solvent inkjet head 20. Further, as shown in FIG. 11B, the droplet number control unit 8 causes the eight liquid droplets 52 to be ejected to the eight ejection positions 60 in the luminance class B pixel region 30. The solvent inkjet head 20 is controlled. Further, as shown in FIG. 11C, the droplet number control unit 8 causes the pixel region 30 of the luminance class C to eject seven solvent droplets 52 at seven ejection positions 60. The solvent inkjet head 20 is controlled.

  As described above, in the method and apparatus for manufacturing an organic EL display device according to the present invention, the thickness unevenness of the light emitting layer can be adjusted by controlling the filling amount of the solvent ink for each pixel region 30, and the luminance A high-quality organic EL display device with reduced unevenness can be manufactured.

  The luminance unevenness occurs depending on the drying speed. For the pixel area 30 that is quickly dried, the amount of the solvent is increased by increasing the number of droplets of the solvent ink, and as a result, the pixel area that is quickly dried. The drying rate of 30 can be reduced.

  In this embodiment, the filling amount of the solvent ink is adjusted. However, the luminance unevenness in the organic EL display device can be improved by adjusting the filling amount of the light emitting layer ink.

  In the conventional example, since it is necessary to completely coat the underlayer, it is necessary to additionally fill the ink for the light emitting layer. However, in the method of the present invention, the underlayer is covered with a small number of droplets. This is because it becomes possible.

  Further, in the conventional example, if the number of droplets of the light emitting layer ink droplets on the pixel region is reduced, insufficient wetting and spreading occurs. However, in the manufacturing method of the present invention, the solvent ink is first used. Since it is applied, insufficient wetting and spreading do not occur even if the number of drops is reduced, and the ink for the light emitting layer can be appropriately controlled. Thus, the occurrence of uneven thickness of the light emitting layer in the pixel region 30 as shown in FIG. 5B is suppressed, and a uniform light emitting layer can be formed in one pixel region 30. As a result, light emission The brightness of the light emitted by the layer is made uniform.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  In addition, you may comprise the manufacturing method and manufacturing apparatus of the organic electroluminescence display of this invention as follows.

(First configuration)
A method of manufacturing an organic electroluminescence display device by applying, by an inkjet method, a first ink in which a component serving as a light emitting layer is contained in a solvent in a region partitioned by a partition on a substrate. A first step in which a second ink that is soluble in the first ink and has a lower viscosity than the first ink is wetted and spread over the entire region, and the first ink is ejected toward the region. And a second step of manufacturing the organic electroluminescence display device.

(Second configuration)
The method for manufacturing an organic electroluminescence display device according to the first configuration, wherein the surface of the region is formed of a solidified aqueous solution.

(Third configuration)
The said 2nd ink consists of a part of component of the said 1st ink, The manufacturing method of the organic electroluminescent display apparatus as described in a 1st structure or a 2nd structure whose boiling point is 200 degrees C or less.

(Fourth configuration)
The region has a substantially rectangular shape, and in the second step, the first ink droplets are sequentially landed from one end side of the plurality of positions at a plurality of positions along the long side direction in the region. The manufacturing method of the organic electroluminescent display apparatus as described in any one of the 1st structure-3rd structure to be made.

(Fifth configuration)
The solvent of the first ink includes a first organic solvent having a boiling point of 200 ° C. or higher and 300 ° C. or lower and a second organic solvent having a boiling point of 200 ° C. or lower, which are mutually soluble. The ink of No. 2 is a method for manufacturing an organic electroluminescence display device according to any one of the first configuration to the fourth configuration having the second organic solvent as a main component.

(Sixth configuration)
The organic material according to any one of the first to fifth configurations, wherein the substrate has a plurality of the regions, and the amount of the second ink applied to each region is adjusted in the first step. A method for manufacturing an electroluminescence display device.

(Seventh configuration)
In the first step, the second ink is composed only of a solvent that does not contain a component that becomes a light emitting layer, and the second ink is composed of a plurality of droplets formed by an inkjet method, The method of manufacturing an organic electroluminescence display device according to the sixth configuration, wherein the adjustment of the amount of the second ink is performed by controlling the number of landings of the droplets on the region.

(Eighth configuration)
A method of manufacturing an organic electroluminescence display device by applying, by an inkjet method, a first ink in which a component that becomes a light emitting layer is contained in a solvent in a region partitioned by a partition on a substrate, A first step in which a second ink that is soluble in the first ink and has a lower viscosity than the first ink is wetted and spread over the entire area; and the first ink is directed to the area. The region has a substantially rectangular shape whose surface is formed of a solidified aqueous solution, and in the second step, a plurality of positions along the long side direction in the region are provided. In addition, the first ink droplets are sequentially landed from one end side of the plurality of positions, and the solvent of the first ink has a boiling point of 100 ° C. or higher and 200 ° C. or lower which dissolves each other. Solvent and boiling point is 200 ℃ or more and 300 ℃ or less Consists of two organic solvents, said second ink manufacturing method of an organic electroluminescence display device which is the first organic solvent.

(Ninth configuration)
A first ink jet head that discharges a first ink in which a component to be a light emitting layer is contained in a solvent; and a second ink that is soluble in the first ink and has a lower viscosity than the first ink. And a plurality of second ink jet heads for discharging the ink. An apparatus for manufacturing an organic electroluminescence display device.

(10th configuration)
Storage means for storing the number of landings of the second ink for each pixel, and determination means for determining a landing pattern for each pixel based on the number of landings, based on information from the determination means The apparatus for manufacturing an organic electroluminescence display device according to the ninth configuration, wherein the second inkjet head is controlled to be discharged.

  The present invention provides a method for manufacturing an organic electroluminescence display device, in which a light-emitting layer having a uniform thickness and no defects can be formed in a pixel region. The present invention can be applied to a method for manufacturing a luminescence display device.

(A)-(c) is a schematic diagram which shows the process in which a light emitting layer is formed on a positive hole transport layer in Embodiment 1 of this invention. (A) is a top view which shows the structure of the inkjet apparatus in Embodiment 1 of this invention, (b) is sectional drawing which shows the cross section of the said inkjet apparatus. It is explanatory drawing which shows the structure of the inkjet head group in Embodiment 1 of this invention. (A)-(d) is a schematic diagram which shows the process in which a light emitting layer is formed on the board | substrate in Embodiment 1 of this invention. (A)-(c) is a schematic diagram which shows the process in which a light emitting layer is formed on a positive hole transport layer in a prior art example. (A)-(c) is a schematic diagram which shows the process in which a light emitting layer is formed on a positive hole transport layer in another prior art example. (A)-(c) is a schematic diagram which shows the relationship between mixing and volatilization of the ink for light emitting layers, and the ink for solvent in Embodiment 1 of this invention. It is a schematic diagram which shows the state of the pixel area | region where the drying nonuniformity between each pixel area | region in the prior art example occurred. It is a schematic diagram which shows the structure of the organic electroluminescent display panel manufacturing apparatus 70 in Embodiment 2 of this invention. (A) And (b) is explanatory drawing which shows the brightness | luminance class for every pixel area, and the quantity of the solvent ink to fill in Embodiment 1 of this invention. (A)-(c) is explanatory drawing which shows the droplet number and discharge position of a solvent droplet corresponding to the brightness | luminance class for every pixel area in Embodiment 2 of this invention.

Explanation of symbols

1 Inkjet device (Organic electroluminescence display device manufacturing device)
3 Substrate 8 Droplet number control unit (control means)
20 Inkjet head for solvent (second inkjet head)
21 Inkjet head for light emitting layer (first inkjet head)
21A Blue inkjet head (first inkjet head)
21B Green inkjet head (first inkjet head)
21C Red inkjet head (first inkjet head)
30 pixel area (partition area)
31 banks
43A Light emitting layer 43B Light emitting layer 43C Light emitting layer 52 Solvent droplet (second solution)
54 Light emitting layer droplet (first solution)
56 Light emitting layer 81 Drop number storage unit (storage means)

Claims (10)

A method for manufacturing an organic electroluminescence display device, wherein a light emitting layer is formed by discharging a first solution containing a light emitting material to a partition region partitioned by a partition on a substrate,
A soluble solution coating step in which a second solution that is soluble in the first solution and has a lower viscosity than the first solution is applied to the entire region of the partition; and
A method of manufacturing an organic electroluminescence display device, comprising: a light emitting solution discharging step of discharging the first solution to the partition region to which the second solution is applied.   2. The method for manufacturing an organic electroluminescent display device according to claim 1, wherein the substrate surface in the partition region is formed of a solidified solution of an aqueous solution. The main component of the second solution is a first organic solvent,
The method of manufacturing an organic electroluminescence display device according to claim 1, wherein the first solution contains the first organic solvent. The partition area is substantially rectangular,
In the luminescent solution discharging step,
When discharging the first solution into the one partition region, the first solution is placed at a plurality of different positions in the partition region from one short side to the other short side of the partition region. 4. The method of manufacturing an organic electroluminescence display device according to claim 1, wherein droplets of the solution are sequentially ejected. 5. The first solution includes a first organic solvent that is a main component of the second solution, and a second organic solvent that is soluble in the first organic solvent,
The first organic solvent has a boiling point of 200 degrees or less,
5. The method of manufacturing an organic electroluminescence display device according to claim 1, wherein the second organic solvent has a boiling point of 200 ° C. or more and 300 ° C. or less. The organic electroluminescence display device includes a plurality of the partition regions,
The organic electroluminescence display according to any one of claims 1 to 5, wherein, in the soluble solution coating step, an amount of the second solution to be discharged is adjusted for each of the partition regions. Device manufacturing method. In the soluble solution coating step,
Discharging a droplet of the second solution into the partition region;
The organic electroluminescence display device according to claim 6, wherein the amount of the second solution discharged to the partition region is adjusted by controlling the number of droplets of the second solution. Production method. The first solution includes a first organic solvent that is a main component of the second solution, and a second organic solvent that is soluble in the first organic solvent,
The first organic solvent has a boiling point of 200 degrees or more and 300 degrees or less,
5. The method of manufacturing an organic electroluminescence display device according to claim 1, wherein the second organic solvent has a boiling point of not less than 100 degrees and not more than 200 degrees. An apparatus for manufacturing an organic electroluminescence display device, wherein a first solution containing a light emitting material is discharged into a partition region partitioned by a partition on a substrate to form a light emitting layer,
A first inkjet head that discharges the first solution to the partition region;
A second inkjet head that is soluble in the first solution and that discharges a second solution having a lower viscosity than the first solution to the partition region;
Organic electroluminescence characterized in that, after the second ink jet head ejects the second solution to the partition region, the first ink jet head ejects the first solution to the partition region. Display device manufacturing equipment. An apparatus for manufacturing an organic electroluminescence display device comprising a plurality of the partition regions,
Storage means for storing the number of droplets of the second solution ejected by the second inkjet head, corresponding to each partition area;
The organic electroluminescence according to claim 9, further comprising: a control unit that controls the droplets ejected by the second inkjet head based on the number of droplets stored in the storage unit. Display device manufacturing equipment.

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