JP6233093B2 - Organic EL device - Google Patents

Description

  The present invention relates to an organic EL device having an organic EL (electroluminescence) thin film.

  Conventionally, there is a coating type organic EL device that forms an organic EL thin film constituting a light emitting layer by a coating method. In a coating-type organic EL device, an organic EL thin film is formed by applying an ink in which an organic EL material is dissolved in a solvent to a display region in which a large number of organic EL elements are formed and used as a display, and then drying the ink. Forming. Specifically, in order to separate each organic EL element, for example, a projection-like bank laid out in a mesh shape is formed in the display area, and the ink is applied to each area separated by the bank while applying the ink. dry. Thereby, it divides | segments into the formation position of each organic EL element, and an organic EL thin film is formed.

  However, when the solvent in the ink is dried, film thickness unevenness occurs, and a phenomenon occurs in which the dried organic EL thin film is thicker in the outer peripheral portion of the display area than in the inner portion. If there is unevenness in film thickness (variation), it will result in uneven brightness when used as a light emitting layer. For this reason, for example, Patent Document 1 discloses a structure in which an outer peripheral region in which a dummy bank is formed is provided so as to surround the outer periphery of the display region, and an organic EL thin film is formed by applying ink to the outer peripheral region. Yes. With such a structure, the film thickness of the organic EL thin film is made constant in the display region located inside the outer peripheral region.

JP 2010-277944 A

  The case where the outer peripheral region is provided so as to surround the outside of the display region as shown in Patent Document 1 and the relationship between the thickness unevenness of the organic EL thin film and the occurrence mechanism of the thickness unevenness will be described with reference to FIGS. To do.

  As shown in FIGS. 5A and 5B, when the display region R1 and the outer peripheral region R2 surrounding the display region R1 are provided, the display region R1 is even as shown in FIGS. 5B and 6A. Become film thickness. On the other hand, as shown in FIG. 5B and FIG. 6B, in the outer peripheral region R2, the film thickness is not uniform and uneven film thickness occurs.

  Specifically, the organic EL device is formed through the following steps. First, as shown in FIG. 7A, the substrate 1 is prepared, and the anode 2 and the drive circuit section 3 are formed on the display region R1 and the outer peripheral region R2. Then, as shown in FIG. Is formed, and an ink 10 is applied thereon as shown in FIG. Then, as shown in FIG. 7D, the solvent of the ink 10 is evaporated and dried. Thereby, the organic EL thin film 5 is formed. Thereafter, as shown in FIG. 7 (e), an organic EL device is manufactured by forming a cathode 6 on the organic EL thin film 5 and the bank 4.

  At this time, as shown in FIG. 7D, the concentration of the solvent evaporated from the ink 10 becomes deeper toward the inner side of the ink application region and thinner toward the outer side. For this reason, the coffee stain phenomenon occurs. The coffee stain phenomenon is a phenomenon in which film thickness unevenness occurs due to a difference in the evaporation rate of the solvent in the solution to be dried. That is, as shown in FIG. 8 (a), the evaporation rate of the solvent in the ink 10 is slow at the center of the solution and fast at the outer edge, so that the concentration of the solution is at the center of the solution as shown in FIG. 8 (b). Thin at the part and dark at the outer edge. Thereby, as shown in FIG. 8C, movement of the solute occurs in the solution, and the solute collects on the outer edge side of the solution. For this reason, as shown in FIG. 8D, a large amount of solute gathers at the position of the outer edge of the solution, and film thickness unevenness occurs in which the film thickness at the outer edge is larger than the position at the center of the organic EL thin film 5. To do.

  Therefore, as shown in FIG. 5B, the organic EL thin film 5 after drying has a thick film thickness due to film thickness unevenness in the outer peripheral area R2 located at the outer edge of the ink application area. For this reason, only the area | region where the film thickness nonuniformity has generate | occur | produced like the display area R1 inside is used as a display.

  However, in such a configuration, as shown in FIGS. 5A and 5B, an outer peripheral region R2 is provided so as to surround the outer periphery of the display region R1, and the drive circuit unit 3 is provided outside the outer peripheral region R2. This leads to an increase in the size of the organic EL device.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an organic EL device capable of realizing a reduction in size of the organic EL device while providing a display region and an outer peripheral region in consideration of film thickness unevenness.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a substrate (1), a first electrode (2) formed on the substrate, and formed on the substrate and electrically connected to the first electrode. The drive circuit section (3), the first electrode and the drive circuit section are formed in a pattern constituting a mesh (4a) partitioned into a plurality of elements so as to protrude from the surface of the first electrode An organic EL thin film (5) comprising a bank (4) composed of the formed insulating material, a light emitting layer disposed in a mesh and including at least one layer composed by a wet technique, and organic The bank is formed in both the display region (R1) functioning as a display and the outer peripheral region (R2) surrounding the outer periphery of the display region. , Nets are also formed in the outer periphery of the bank Are being organic EL thin film with have the form, the driver circuit portion is formed penetrates into the outer peripheral region, is characterized in that the bank is formed to project from the surface of the drive circuit unit.

  In this way, the drive circuit unit is inserted below the outer peripheral region provided so as to surround the outer periphery of the display region. For this reason, the width of the outer peripheral area itself is not changed from the conventional one, and the drive circuit section is inserted below the outer peripheral area, so that the area of the drive circuit section overlapped with the outer peripheral area is overlapped. It can be reduced compared to the case where it is not. Therefore, it is possible to reduce the size of the organic EL device.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

It is the figure which showed the organic EL apparatus 100 concerning 1st Embodiment of this invention, (a) is the upper surface layout figure of the organic EL apparatus 100, (b) is IB-IB 'sectional drawing of (a). It is the upper surface layout figure which expanded a part of display field R1 and peripheral field R2 of organic EL device 100 concerning a 2nd embodiment of the present invention. FIG. 3 is a diagram showing how ink 10 is applied in the display area R1 and the outer peripheral area R2 in the area A of FIG. It is the upper surface layout figure which expanded a part of display region R1 and peripheral field R2 of organic EL device 100 explained by other embodiments. It is the figure which showed the organic EL apparatus 100 of the conventional structure, (a) is the upper surface layout figure of the organic EL apparatus 100, (b) is VB-VB 'sectional drawing of (a). (A) is the elements on larger scale in display area R1, (b) is the elements on larger scale in outer peripheral area R2. 5 is a cross-sectional view showing a manufacturing process of the organic EL device 100. FIG. It is sectional drawing which showed the mechanism of the coffee stain phenomenon.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
The organic EL device according to the first embodiment of the present invention will be described. The organic EL device according to the present embodiment can be applied to a display such as a navigation system provided in a vehicle, for example.

  As shown in FIGS. 1A and 1B, an organic EL device 100 according to this embodiment is a horizontally long panel, and includes a substrate 1, an anode 2, a drive circuit unit 3, a bank 4, an organic EL thin film 5, and a cathode. 6 or the like.

  The substrate 1 is composed of, for example, a transparent glass substrate, a quartz glass substrate, a resin substrate with a barrier film, or the like.

  The anode 2 serves as a hole injection electrode, and is formed of any conductive material capable of forming a transparent or translucent electrode. Specifically, the anode 2 is formed using indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, zinc oxide, indium oxide, zinc aluminum oxide, zinc gallium oxide, titanium niobium oxide, or the like as the oxide. can do. In particular, ITO is a suitable material having advantages such as low resistance, solvent resistance, and excellent transparency.

  The anode 2 only needs to be formed at least in the display region R1 used as a display, but in the present embodiment, the anode 2 is also formed in the outer peripheral region R2. However, as will be described later, the anode 2 is not formed in the portion of the outer peripheral region R2 where the drive circuit unit 3 is disposed.

  The drive circuit unit 3 includes a circuit element for driving the organic EL element, for example, a drive circuit having a TFT (not shown). The drive circuit unit 3 is configured by, for example, a semiconductor device chip, and is connected to the anode 2 through the circuit pattern. And is electrically connected to the cathode 6. FIG. 1B shows a cross section in which the drive circuit unit 3 is partially connected to the cathode 6, but the drive circuit unit 3 is also connected to the anode 2 in a different cross section.

  The bank 4 is made of an ink-repellent insulating material, and is made of, for example, polyimide or acrylic. The bank 4 forms a section that divides the organic EL thin film 5 for each pixel of the organic EL element. For example, the bank 4 is formed in a protruding shape as shown in FIG. 1B, and as shown in FIG. Are laid out in a mesh pattern. In the case of the present embodiment, the display area R1 and the outer peripheral area R2 have the same layout, and the shape in the mesh 4a is an elongated shape having one direction as a longitudinal direction, specifically a rectangular shape, and the longitudinal direction is an organic EL device. They are arranged so as to coincide with the longitudinal direction of 100. In the display region R1, the plurality of meshes 4a formed in the outer peripheral region R2 are arranged in a line on a line in which the plurality of meshes 4a are arranged in a direction parallel to the longitudinal direction of the mesh 4a.

  As shown in FIG. 1A, the bank 4 is formed not only in the display area R1 but also in an outer peripheral area R2 surrounding the outer periphery of the display area R1. Further, the drive circuit unit 3 is inserted under the portion of the bank 4 located in the outer peripheral region R2, and at least part of the drive circuit unit 3 enters the outer peripheral region R2. The bank 4 formed in the outer peripheral region R2 is formed with a contact hole 4b in which the organic EL thin film 5 is not disposed so that the drive circuit unit 3 and the cathode 6 can be electrically connected. The cathode 6 is embedded in the contact hole 4b. The bank 4 basically has the same pattern in the display region R1 and the outer peripheral region R2, and the contact hole 4b is formed at a position different from the inside of the mesh 4a constituting each organic EL element. .

  The organic EL thin film 5 serves as a light emitting layer, and is formed in the mesh 4a partitioned by the bank 4, that is, in a portion where the bank 4 except for the contact hole 4b is not formed. For example, the organic EL thin film 5 is made of a polymer material (polymer organic light emitting material). As the polymer material, a polyfluorene (PFO) polymer, a polyphenylene vinylene (PPV) polymer, a polyvinyl carbazole (PVK) polymer, or the like can be used, and a fluorescent dye or a phosphorescent dye can be used as the polymer. Also, those dispersed in polystyrene-based polymers, polythiophene-based polymers, polymethylmethacrylate-based polymers, and the like can be used. These polymer materials are dissolved in an organic solvent as a solvent to prepare an ink (coating liquid). After the ink is applied, the organic solvent is dried to form the organic EL thin film 5. For example, 1-phenylheptane or 1-phenylhexane can be used as the organic solvent.

  Here, the constituent material of the organic EL thin film 5 is only a polymer material, but a low molecular material may be added to the polymer material in order to obtain a binder effect.

  As a coating method for forming the polymer material in the organic EL thin film 5, a wet method such as a spin coating method, an ink jet method, a printing method, a dip coating method, or a spray method can be used. And after apply | coating the organic EL thin film 5, the organic EL thin film 5 is formed by performing the drying process which volatilizes an organic solvent.

  The cathode 6 constitutes an electron injection electrode and is made of a metal electrode material such as aluminum. The cathode 6 is formed on the organic EL thin film 5 and is formed so as to sandwich the organic EL thin film 5 with the anode 2.

  With such a structure, the organic EL device 100 according to the present embodiment is configured. In the organic EL device 100 configured as described above, as shown in FIG. 1B, the organic EL thin film 5 is formed with a uniform thickness in the display region R1, and from the display region R1 in the outer peripheral region R2. The film thickness gradually increases toward the outside. And since the film thickness of the organic EL thin film 5 is uniform in the display region R1, it is possible to display information without uneven brightness by using this portion as a display.

  In the organic EL device 100, the drive circuit unit 3 is inserted below the outer peripheral region R2. Since the range in which the film thickness unevenness of the organic EL thin film 5 occurs due to the coffee stain phenomenon is determined by the material and concentration of the polymer material and organic solvent for forming the organic EL thin film 5, the width of the outer peripheral region R2 is the film thickness. The width corresponds to the range where the thickness unevenness occurs. The width itself of the outer peripheral region R2 is not changed from the conventional one, and the drive circuit unit 3 is inserted below the outer peripheral region R2, so that the outer peripheral region R2 of the drive circuit unit 3 is overlapped. Compared to the case where the areas of the portions do not overlap, the size can be reduced. Therefore, as can be seen by comparing FIGS. 1A and 1B with FIGS. 5A and 5B, the portion of the organic EL device 100 shown by the broken lines in FIGS. It is possible to reduce the size.

In addition, the manufacturing method of the organic EL device 100 configured as described above is basically the same as the manufacturing method described in FIG. However, when the drive circuit unit 3 is arranged, the drive circuit unit 3 is arranged so as to enter the portion of the substrate 1 that is the outer peripheral region R2, and when the bank 4 is formed, the bank 4 is connected to the drive circuit unit 3 It is also formed on the top. For the bank 4, for example, after a film of polyimide, acrylic, or the like is formed, patterning is performed by plasma processing using CF ₄ so that a net-like layout is obtained. At this time, a contact hole 4b is formed at a position different from the mesh 4a where the organic EL thin film 5 is formed in a portion of the bank 4 formed on the drive circuit unit 3. Thus, when ink is applied to the mesh 4a of the bank 4, it can be prevented from being applied to the contact hole 4b, and when the cathode 6 is formed in a later process, the cathode 6 enters the contact hole 4b and is driven. It can be electrically connected to a desired position of the circuit unit 3.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the layout of the bank 4 is changed with respect to the first embodiment, and the other parts are the same as those in the first embodiment. Therefore, only different portions from the first embodiment will be described.

  As shown in FIG. 2, in the present embodiment, the portion of the bank 4 that is formed on the drive circuit portion 3, that is, the portion that forms the contact hole 4b, has a different layout from the portion that is formed in the display region R1. It is trying to become.

  Specifically, in the display area R1, the meshes 4a formed by the banks 4 are divided into rectangles, and the meshes 4a are arranged at equal intervals in the vertical and horizontal directions. . In the case of the present embodiment, the rectangular meshes 4 a are arranged so that the longitudinal direction of each mesh 4 a coincides with the longitudinal direction of the organic EL device 100.

  On the other hand, in the outer peripheral region R2, the meshes 4a constituted by the banks 4 are basically rectangular, and the meshes 4a adjacent in the direction perpendicular to the longitudinal direction of the meshes 4a have a relatively large width. The first mesh portion 4c and the relatively small second mesh portion 4d are alternately arranged. Further, the adjacent meshes 4a, that is, the first mesh part 4c and the second mesh part 4d are connected, for example, at the connecting part 4e at the center position of the long side of the rectangle constituting each mesh 4a, and the organic EL thin film 5 The ink for forming the ink enters the connecting portion 4e.

  As for the outer peripheral region R2, the area of the adjacent meshes 4a per unit area, that is, the total area of the ink application area and the area of the connecting portion 4e is the sum of the meshes 4a per unit area in the display region R1. The dimensions are designed so that the area, that is, the ink application area is the same. Specifically, the ink application area in each of the regions B1 and B2 surrounded by a line in FIG. 3 in the display region R1 and the outer peripheral region R2, that is, the unit area is defined as an area including two adjacent meshes 4a. In this case, the ink application area per unit area is the same in the display region R1 and the outer peripheral region R2.

  As a result, in the outer peripheral region R2, since the ink is also applied to the connecting portion 4e, the total size of the width of the first mesh portion 4c and the width of the second mesh portion 4d is set to the width of the adjacent mesh 4a in the display region R1. Therefore, the interval between the adjacent meshes 4a can be longer than the display area R1. For this reason, by forming the contact hole 4b between the adjacent meshes 4a, it becomes possible to further secure the area of the contact hole 4b.

  Further, in the outer peripheral region R2, the areas of the adjacent meshes 4a are different, but the meshes 4a are connected by providing the connecting portions 4e. For this reason, when the ink is applied to each mesh 4 a, the ink height can be made uniform and the ink can be prevented from overflowing from the bank 4.

  That is, the ink application is basically performed in a uniform manner without changing the ink application amount in the display region R1 and the outer peripheral region R2. For this reason, if the areas of adjacent meshes 4a are different as in the outer peripheral region R2, if the connecting portion 4e is not provided, the area of the mesh 4a is smaller than the area of the mesh 4a being wider. Thus, the height of the applied ink is increased. For this reason, the ink may overflow from the bank 4. However, since the ink is allowed to flow between the adjacent meshes 4a by providing the connecting portions 4e, the ink height can be made uniform in each mesh 4a. Therefore, it is possible to prevent the ink from overflowing from the bank 4.

  Further, since the ink application area per unit area is equal to the display area R1 in the outer peripheral area R2, as shown in FIG. 3, the ink application along the longitudinal direction of each mesh 4a formed in a rectangle is performed. When performing the above, the amount of ink applied to each of the regions R1, R2 can be made uniform. Therefore, the ink application nozzles that have been conventionally used can be used as they are.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, the shape of the organic EL device 100 and the layout of the bank 4 are not limited to those described in the above embodiments. Specifically, the organic EL device 100 is not limited to a rectangular shape, and may be a square or another shape. Further, for the bank 4, in the outer peripheral region R2, the shape of the adjacent mesh 4a is not a rectangle, but may be, for example, the shape shown in FIG.

  That is, as shown in FIG. 4 (a), a L-shaped part 4g is arranged on both sides of the T-shaped part 4f, and a contact hole is arranged between the meshes 4a. The area of the mesh 4a of the T-shaped part 4f and the L-shaped part 4g is set to be the same. In this way, even if the connecting portion 4e as shown in the second embodiment is not provided, the height of the ink at each mesh 4a can be made uniform, and the overflow of the ink from the bank 4 can be suppressed. .

  Further, the arrangement place of the connecting portions 4e is not limited to the center position of the long side of the rectangle constituting each mesh 4a, but may be connected by the connecting portions 4e at both ends in the longitudinal direction.

  In each of the above-described embodiments, the anode 2 as the first electrode formed on the substrate 1 and the cathode 6 as the second electrode formed through the bank 4 and the organic EL thin film 5 are sequentially formed. However, the first electrode may be the cathode 6 and the second electrode may be the anode 2 upside down.

  In each of the above embodiments, the case where the organic EL thin film 5 constituting the light emitting layer is constituted by one layer has been described, but it may be formed by a plurality of layers. Even in such a case, if the organic EL thin film 5 includes at least one layer formed by a wet method, the film thickness variation due to the coffee stain phenomenon as described above occurs. Therefore, it is preferable to apply the present invention. .

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Drive circuit part 4 Bank 4a Mesh 4b Contact hole 4c, 4d First and second mesh part 5 Organic EL thin film 6 Cathode 10 Ink R1 Display area R2 Outer peripheral area

Claims (3)

A substrate (1);
A first electrode (2) formed on the substrate;
A drive circuit unit (3) formed on the substrate and electrically connected to the first electrode;
An insulating material formed on the first electrode and the drive circuit unit in a pattern that forms a mesh (4a) partitioned into a plurality of elements and formed so as to protrude from the surface of the first electrode A configured bank (4);
An organic EL thin film (5) constituting a light emitting layer disposed in the mesh and including at least one layer constituted by a wet method;
A second electrode (6) formed on the organic EL thin film,
The bank is formed in both the display area (R1) functioning as a display and the outer peripheral area (R2) surrounding the outer periphery of the display area, and the mesh is also formed in a portion of the bank formed in the outer peripheral area. And the organic EL thin film is formed,
The drive circuit unit is formed so as to enter the outer peripheral region, and the bank is formed so as to protrude from the surface of the drive circuit unit,
The mesh is an elongated shape having one direction as a longitudinal direction, and in the display region and the outer peripheral region, a plurality of the meshes are arranged adjacent to each other in a longitudinal direction and a direction perpendicular to the longitudinal direction, A plurality of meshes formed in the outer peripheral region are arranged side by side on a straight line formed by a plurality of meshes arranged along the longitudinal direction of the meshes in the display region,
In the outer peripheral region, the meshes adjacent to each other in the direction perpendicular to the longitudinal direction of the meshes are compared, and the first mesh part (4c) having a wider width in the perpendicular direction of the meshes and the meshes than the first mesh part. Second mesh portions (4d) having a narrow width in the vertical direction are alternately and repeatedly formed, and the first mesh portion and the second mesh portion adjacent in the vertical direction of the meshes are connected to each other. Connected to each other via the part (4e),
The area including the two adjacent meshes as a unit area of the outer peripheral region, the area of the mesh per unit area in the display region, and the mesh and the connection per unit area in the outer peripheral region An organic EL device having equal areas. A contact hole (4b) is formed in the bank at a position different from the mesh in a region where the drive circuit unit is formed in the outer peripheral region, and the second electrode and the drive circuit unit are formed through the contact hole. The organic EL device according to claim 1, wherein and are electrically connected. The organic EL device according to claim 2 , wherein the contact hole is formed between the first mesh portion and the second mesh portion.

Images