CN111788865A

CN111788865A - Organic EL display device

Info

Publication number: CN111788865A
Application number: CN201980015968.2A
Authority: CN
Inventors: 高城淳
Original assignee: Japan Display Inc
Current assignee: Japan Display Inc
Priority date: 2018-03-07
Filing date: 2019-03-04
Publication date: 2020-10-16
Anticipated expiration: 2039-03-04
Also published as: WO2019172187A1; CN111788865B; JP2019160393A

Abstract

The organic EL display device includes: a plurality of pixel electrodes; an organic insulating layer provided on the plurality of pixel electrodes and having an opening at a position overlapping with a part of an upper surface of each of the plurality of pixel electrodes in a plan view; a light-emitting layer provided on the organic insulating layer and covering the opening; and a common electrode provided over the light-emitting layer so as to extend over the plurality of pixel electrodes, wherein a distance L1 between the light-emitting regions adjacent in a first direction is larger than a distance L2 between the light-emitting regions adjacent in a second direction intersecting the first direction when a region of the pixel electrodes located inside the opening is defined as a light-emitting region in a plan view.

Description

Organic EL display device

Technical Field

The present invention relates to an organic EL display device using an organic EL (Electro Luminescence) material as a light emitting material.

Background

An organic EL element included in an organic EL display device has a structure in which a light-emitting layer made of an organic EL material is provided between an anode (anode) and a cathode (cathode). The organic EL element emits light by flowing current in the light-emitting layer using an anode and a cathode. As the organic EL material, either a high molecular material or a low molecular material can be used, but a method using a low molecular organic EL material is now mainstream.

A light-emitting layer using a low-molecular organic EL material is generally formed on a substrate by an evaporation method. That is, the organic EL material is heated and evaporated, and the evaporated organic EL material is attached to the substrate, thereby forming a thin film. As one of such vapor deposition apparatuses, a vertical vapor deposition apparatus in which a substrate is arranged upright in the vapor deposition apparatus is known (for example, patent documents 1 and 2). Such a vertical vapor deposition apparatus is advantageous in that it can process a large substrate in a standing state, and thus can reduce an occupied area.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012 and 84544.

Patent document 2: japanese patent laid-open No. 2014-70239.

Disclosure of Invention

Technical problem to be solved by the invention

In the case of using the vertical vapor deposition device, the vapor deposition mask needs to be arranged upright in accordance with the substrate. In this case, the vapor deposition mask becomes large as the substrate becomes large, and deflection of the vapor deposition mask due to its own weight may become a problem.

Fig. 12A is a front view showing an example of a vapor deposition mask 80 used in a vertical vapor deposition device. The vapor deposition mask 80 includes a plurality of electroforming masks 80b in a mask frame 80a made of invar material or the like. The electroforming mask 80b is a mask made of a metal film formed by electroforming, and has a plurality of openings in the metal film. Each electroforming mask 80b corresponds to 1 organic EL display device. In fig. 12A, although the electroforming mask 80b appears to have 1 opening, actually, the plurality of openings are arranged corresponding to the positions of the respective pixels of the organic EL display device.

Fig. 12B is a front view showing an example of a case where the vapor deposition mask 80 used in the vertical vapor deposition device is arranged upright. As shown in fig. 12B, the vicinity of the center of the vapor deposition mask 80 is deflected downward (in the direction of action of gravity) by its own weight. As a result, the upper and lower sides of the vapor deposition mask 80 shown in fig. 12B are bent at the center of the corner portions.

Here, fig. 13A is a plan view showing a state of alignment of the vapor deposition mask in a case where no deflection is generated in the vapor deposition mask 80. Fig. 13A shows a red light emitting region 20Ra, a green light emitting region 20Ga, and a blue light emitting region 20 Ba. Here, the "light-emitting region" refers to a region that actually emits light in a pixel. Specifically, the term "refers to a region located inside the bank portion on the upper surface of the pixel electrode described later.

In the example shown in fig. 13A, the plurality of openings 80d provided in the metal film 80c constituting the electroforming mask 80b are positionally aligned with respect to the light-emitting regions 20 Ra. Therefore, when the evaporation of the organic EL material emitting red light is performed in the state shown in fig. 13A, a light emitting layer emitting red light is formed in the light emitting region 20 Ra.

Next, fig. 13B is a plan view showing a state of alignment of the vapor deposition mask when the vapor deposition mask 80 is deflected. In this case, the position of the opening 80D is shifted downward in the direction D1 (direction in which gravity acts) due to the deflection of the vapor deposition mask 80 by its own weight, and the light-emitting region 20Ra and the opening 80D are misaligned. As a result, in fig. 13B, a light-emitting layer emitting red light is formed over the light-emitting region 20Ra and the light-emitting region 20Ga in some cases. Such a defective formation of the light emitting layer causes occurrence of pixel color mixture and reduction in manufacturing process yield.

One of the technical problems of the present invention is to provide an organic EL display device in which a failure in formation of a light-emitting layer due to deflection of a vapor deposition mask is prevented.

Means for solving the problems

An organic EL display device according to an embodiment of the present invention includes: a plurality of pixel electrodes; an organic insulating layer provided on the plurality of pixel electrodes and having an opening at a position overlapping with a part of an upper surface of each of the plurality of pixel electrodes in a plan view; a light-emitting layer provided on the organic insulating layer and covering the opening; and a common electrode provided over the light-emitting layer so as to extend over the plurality of pixel electrodes, wherein a distance L1 between the light-emitting regions adjacent in a first direction is larger than a distance L2 between the light-emitting regions adjacent in a second direction intersecting the first direction when a region of the pixel electrodes located inside the opening is defined as a light-emitting region in a plan view.

An organic EL display device according to an embodiment of the present invention includes: a plurality of pixel electrodes; an organic insulating layer provided on the plurality of pixel electrodes and having an opening at a position overlapping with a part of an upper surface of each of the plurality of pixel electrodes in a plan view; a light-emitting layer provided on the organic insulating layer and covering the opening; and a common electrode provided on the light-emitting layer and provided so as to extend over the plurality of pixel electrodes, the plurality of pixel electrodes including: a first pixel electrode; a second pixel electrode adjacent to the first pixel electrode in the first direction; and a third pixel electrode adjacent to the first pixel electrode on a side opposite to the second pixel electrode, wherein the light-emitting layer includes a first light-emitting layer facing the first pixel electrode and overlapping the organic insulating layer, and a distance d1 between an end of the first light-emitting layer and the light-emitting region of the first pixel electrode in a direction from the first pixel electrode toward the second pixel electrode is greater than a distance d2 between an end of the first light-emitting layer and the light-emitting region of the first pixel electrode in a direction from the first pixel electrode toward the third pixel electrode, when a region of the pixel electrode located inside the opening is a light-emitting region in a plan view.

Drawings

Fig. 1 is a plan view showing the structure of an organic EL display device according to a first embodiment.

Fig. 2 is a sectional view showing the structure of a pixel in the first embodiment.

Fig. 3 is a plan view showing the structure of a pixel in the organic EL display device according to the first embodiment.

Fig. 4 is a cross-sectional view of the display region shown in fig. 3 cut along a one-dot chain line IV-IV in the direction D1.

Fig. 5 is a cross-sectional view of the display region shown in fig. 3 cut along a one-dot chain line V-V in the direction D2.

Fig. 6 is an enlarged plan view of a part of the display region in the organic EL display device of the first embodiment.

Fig. 7 is a sectional view showing a manufacturing process of the organic EL display device according to the first embodiment.

Fig. 8 is a sectional view showing a manufacturing process of the organic EL display device according to the first embodiment.

Fig. 9A is a front view showing an example of the vapor deposition mask according to the first embodiment.

Fig. 9B is a plan view showing a state where a light-emitting layer (specifically, a light-emitting layer emitting red light) is formed by a vapor deposition method.

Fig. 9C is a plan view showing a state where a light-emitting layer (specifically, a light-emitting layer emitting red light) is formed by a vapor deposition method.

Fig. 10 is a sectional view showing a manufacturing process of the organic EL display device according to the first embodiment.

Fig. 11A is a plan view showing the structure of a pixel in the organic EL display device according to the second embodiment.

Fig. 11B is a plan view showing the structure of a pixel in the organic EL display device according to the second embodiment.

Fig. 12A is a front view showing an example of a vapor deposition mask used in a vertical vapor deposition device.

Fig. 12B is a front view showing an example of a case where a vapor deposition mask used in a vertical vapor deposition device is arranged upright.

Fig. 13A is a plan view showing a state of alignment of the vapor deposition mask when the vapor deposition mask is not deflected.

Fig. 13B is a plan view showing a state of alignment of the vapor deposition mask when the vapor deposition mask is deflected.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be carried out in various ways without departing from the scope of the gist thereof, and is not limited to the description of the embodiments illustrated below. The drawings schematically show the width, thickness, shape, and the like of each part as compared with the actual form in order to make the description clearer, but the drawings are merely examples and do not limit the explanation of the present invention. In the present specification and the drawings, elements having the same functions as those described with reference to the already-described figures are denoted by the same reference numerals, and redundant description may be omitted.

In the present specification and claims, "upper" and "lower" refer to relative positional relationships based on a surface (hereinafter, simply referred to as "surface") of the substrate on which the light-emitting element is formed. For example, in this specification, a direction from the surface of the substrate to the light-emitting element is referred to as "up", and a direction opposite thereto is referred to as "down". In the present specification and claims, the term "upper" when used to describe a state in which another structure is disposed on a certain structure includes both a case in which another structure is disposed immediately above the certain structure so as to be in contact with the certain structure and a case in which another structure is disposed above the certain structure with another structure interposed therebetween, unless otherwise specified.

(first embodiment)

< Structure of organic EL display device >

Fig. 1 is a plan view showing the structure of an organic EL display device 100 according to a first embodiment. In fig. 1, an array substrate 101 is a substrate in which a plurality of pixels including organic EL elements are formed on the front surface side of a support substrate (not shown). The array substrate 101 is also referred to as an active matrix substrate.

The array substrate 101 includes a pixel region 20 and a peripheral region 22. In the pixel region 20, a plurality of pixels 20a including organic EL elements are arranged. Specifically, the pixels 20a are arranged in the D1 direction (column direction) and the D2 direction (row direction) shown in fig. 1, and are arranged in a matrix as a whole. In the peripheral region 22, a circuit (for example, a shift register circuit) for transmitting a signal to the pixel 20a is arranged. However, in the present embodiment, there is no particular limitation on what kind of circuit elements are arranged in the peripheral region 22. In addition, in the pixel region 20, not only pixels that actually contribute to image display but also dummy pixels that do not contribute to image display may be provided. In this case, a region where pixels contributing to image display are provided may be referred to as a display region.

The array substrate 101 includes a terminal region 24 as a part of the peripheral region 22. In the terminal region 24, a plurality of wires are collected, and the flexible printed circuit board 26 is electrically connected to these wires. Signals (for example, video signals) transmitted from an external device through the flexible printed circuit board 26 are transmitted to the pixels 20a through a plurality of wires extending from the terminal region 24.

In the present embodiment, a drive circuit 28 formed of an IC chip or the like is mounted on the flexible printed circuit board 26. The drive circuit 28 has a function of transmitting a control signal such as a start pulse to a shift register circuit or the like disposed in the peripheral region 22, or performing predetermined signal processing on a video signal. However, the drive circuit 28 is not necessarily configured, and may be omitted.

Next, the structure of the pixel 20a of the organic EL display device 100 according to the present embodiment will be described. The pixel 20a shown in fig. 1 is actually composed of 3 sub-pixels (sub-pixels) corresponding to 3 colors of RGB. However, for convenience of explanation, 1 subpixel will be explained here.

Fig. 2 is a sectional view showing the structure of a pixel 20a in the first embodiment. In fig. 2, a thin film transistor 50 is provided over a support substrate 201 with a base film 202 interposed therebetween. In the present embodiment, a glass substrate is used as the support substrate 201, but a substrate made of a resin material such as acrylic resin or polyimide may be used. As the base film 202, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film is used.

The thin film transistor 50 is a so-called top gate type thin film transistor. However, the present invention is not limited to this, and any type of thin film transistor may be provided. The thin film transistor 50 shown in fig. 2 functions as a driving transistor for supplying current to the organic EL element 60. In this embodiment, an N-channel transistor is used as the thin film transistor 50. Since the structure of the thin film transistor 50 is a known structure, a detailed description thereof will be omitted.

The thin film transistor 50 is connected to the holding capacitor 55. The holding capacitor 55 can be configured by 2 conductive films configuring the thin film transistor 50 and an insulating film provided therebetween. For example, the storage capacitor 55 of the present embodiment can be formed using a semiconductor layer constituting an active layer of the thin film transistor 50, a gate insulating film, and a capacitor electrode (an electrode formed simultaneously with the gate electrode). However, the configuration of the holding capacitor 55 is not limited thereto.

The thin film transistor 50 is covered with an organic insulating film 120. The organic insulating film 120 functions as a planarizing film for planarizing the undulation caused by the shape of the thin film transistor 50. In this embodiment, an insulating film containing a resin material such as an acrylic resin or a polyimide resin is used as the organic insulating film 120.

The organic insulating film 120 is provided with an opening 122. The opening portion 122 is covered with an oxide conductive film 124. In this embodiment, a thin film formed by patterning a thin film made of a metal oxide material such as ito (indium Tin oxide) or izo (indium zinc oxide) is used as the oxide conductive film 124. However, the present invention is not limited thereto, and other oxide conductive films may be used. The oxide conductive film 124 is connected to a part (specifically, a source electrode) of the thin film transistor 50 exposed from the opening portion 122.

Further, on the upper surface of the organic insulating film 120, a lower electrode 126 of the storage capacitor 57 is formed using an oxide conductive film formed simultaneously with the oxide conductive film 124. The lower electrode 126 is disposed below the organic EL element 60. As described later, since the organic EL element 60 of the present embodiment has a structure for emitting light upward, the storage capacitor 57 can be formed by a space below the organic EL element 60.

An inorganic insulating film 128 is provided over the oxide conductive film 124 and the lower electrode 126. In this embodiment, a silicon nitride film is used as the inorganic insulating film 128, but the present invention is not limited thereto, and other inorganic insulating films such as a silicon oxide film and a silicon nitride oxide film may be used. The inorganic insulating film 128 is provided with an opening 130a for exposing the organic insulating film 120. The opening 130a functions as the drain region 65. The drain region 65 functions to drain moisture and the like generated from the organic insulating film 120 by the heating process after the formation of the organic insulating film 120 to the outside.

A pixel electrode 132 is provided over the inorganic insulating film 128. The pixel electrode 132 is connected to the oxide conductive film 124 through an opening 130b provided in the inorganic insulating film 128. That is, the pixel electrode 132 is connected to the thin film transistor 50 through the oxide conductive film 124. The pixel electrode 132 also functions as an upper electrode of the storage capacitor 57 and also functions as an anode (anode electrode) of the organic EL element 60.

In this embodiment, a conductive film having a stacked structure in which a silver-containing layer is sandwiched between oxide conductive films is used as the pixel electrode 132. Specifically, the pixel electrode 132 is composed of an IZO layer, a silver layer, and an IZO layer. However, instead of the IZO layer, an ITO layer may be used. In order to be configured such that light emitted from the organic EL element 60 is emitted upward, the pixel electrode 132 preferably includes a reflective conductive film. Therefore, in this embodiment, a layer made of a metal material containing silver or a silver alloy having high reflectance is used as a part of the pixel electrode 132.

In this embodiment, the dielectric of the storage capacitor 57 is a silicon nitride film having a higher dielectric constant than other insulating films, and thus a large capacitance can be easily secured. Further, since the organic EL element 60 can be disposed by effectively utilizing the space below it, there is an advantage that it is easy to secure a large occupied area of the storage capacitor 57.

A part of the pixel electrode 132 is covered with a bank portion 134 made of an organic material. Specifically, the bank 134 covers an end of the pixel electrode 132, and has an opening 136 that exposes a part of the upper surface of the pixel electrode 132. The part of the upper surface of the pixel electrode 132 thus exposed (i.e., the region of the upper surface of the pixel electrode 132 located inside the opening 136 of the bank 134) becomes a substantial light-emitting region of the pixel 20 a. That is, the bank 134 functions to define the light emitting region of the pixel 20 a. As the organic material constituting the bank 134, a resin material such as a photosensitive acrylic resin or a polyimide resin can be used, but the organic material is not limited thereto.

The light-emitting layer 138 is provided in a region of the upper surface of the pixel electrode 132 that does not overlap with the bank 134 (i.e., a region inside the opening 136). In this embodiment, the light-emitting layer 138 is formed by vapor deposition of an organic EL material by a vapor deposition method using a vertical vapor deposition apparatus. For example, an organic EL material emitting light of any one of red, blue, and green colors can be used for the light-emitting layer 138. In fig. 2, only the light-emitting layer 138 is illustrated, but an electron injection layer, an electron transport layer, an electron blocking layer, a hole injection layer, a hole transport layer, and/or a hole blocking layer may be provided in addition thereto. In this case, functional layers such as an electron injection layer, an electron transport layer, an electron blocking layer, a hole injection layer, a hole transport layer, and a hole blocking layer may be provided over a plurality of pixels.

A common electrode 140 made of a conductive film containing a group 1 element or a group 2 element is provided over the light-emitting layer 138. As such a conductive film, for example, a magnesium (Mg) film, a lithium (Li) film, or the like can be used. In this embodiment, an MgAg film, which is an alloy of magnesium and silver, is used as the conductive film containing a group 2 element. The common electrode 140 functions as a cathode (cathode electrode) of the organic EL element 60. In addition, the common electrode 140 is disposed over a plurality of pixels.

In the case of a top emission type display device in which light emitted from the light emitting layer 138 is extracted from the upper surface side, that is, the common electrode 140 side, the common electrode 140 is required to have light transmittance. When the conductive film containing the group 1 element or the group 2 element is used as the common electrode 140, the common electrode 140 is formed to have a thin film thickness to allow transmission of emitted light in order to provide light transmittance. Specifically, the common electrode 140 has a film thickness of 10nm to 30nm, which can provide light transmittance.

The pixel electrode 132, the light-emitting layer 138, and the common electrode 140 described above constitute the organic EL element 60.

A sealing film 142 is provided on the common electrode 140 (i.e., on the organic EL element 60). The sealing film 142 of the present embodiment is composed of three layers, which are, in order from below, a first sealing film 142a composed of an inorganic material, a second sealing film 142b composed of an organic material, and a third sealing film 142c composed of an inorganic material. These sealing films play a role of preventing moisture and the like from entering from the outside and preventing deterioration of the light-emitting layer 138 and the common electrode 140.

In this embodiment, a silicon nitride film is used as the first sealing film 142a and the third sealing film 142 c. However, the present invention is not limited to this, and a silicon oxide film or a silicon nitride oxide film may be used instead of the silicon nitride film. That is, as the first sealing film 142a, an inorganic insulating film can be used. As the inorganic insulating film, an insulating film containing silicon nitride is particularly preferably used.

Further, as the second sealing film 142b, an organic insulating film made of a resin material is used. In this embodiment, by using an organic insulating film made of a resin material as the second sealing film 142b, the undulation formed by the bank 134 can be flattened. The first sealing film 142a has a film thickness of about 1 μm and is thus formed along an inclined plane relative to the bank section 134. On the other hand, since the second sealing film 142b is formed to have a film thickness of about 10 μm, it is possible to sufficiently fill the step such as the opening 136 provided in the bank 134. Therefore, by using the organic insulating film as the second sealing film 142b, the irregularities generated on the upper surface of the second sealing film 142b can be made smaller than the irregularities generated on the upper surface of the first sealing film 142 a.

< Structure of pixel >

Fig. 3 is a plan view showing the structure of a pixel in the organic EL display device 100 according to the first embodiment. Specifically, fig. 3 corresponds to a plan view of the pixel electrode 132 described with reference to fig. 2 in which the light-emitting layer 138 is formed on a part of the upper surface (i.e., the light-emitting region) and the bank 134. As shown in fig. 3, a red light emitting region 20Ra, a green light emitting region 20Ga, and a blue light emitting region 20Ba are arranged in the pixel region 20. A light-emitting layer 138R made of a red-light-emitting organic EL material, a light-emitting layer 138G made of a green-light-emitting organic EL material, and a light-emitting layer 138B made of a blue-light-emitting organic EL material are formed on the light-emitting region 20Ra, the light-emitting region 20Ga, and the light-emitting region 20Ba, respectively.

At this time, as shown in fig. 3, for example, a distance L1 between the light-emitting region 20Ra and the light-emitting region 20Ga adjacent in the D1 direction is larger than a distance L2 between the light-emitting region 20Ra and the light-emitting region 20Ba adjacent in the D2 direction. As described above, in the organic EL display device 100 according to the present embodiment, there is a margin for positional displacement of the light-emitting layer between the light-emitting regions (which may be referred to as between pixels) in the direction D1 (specifically, in a direction parallel to the direction in which gravity acts). Therefore, as described above, even if the vapor deposition mask is bent by its own weight in the vertical vapor deposition device, the organic EL display device 100 can be formed without causing a defect in the formation of the light emitting layer.

Here, fig. 4 is a cross-sectional view of the pixel region 20 shown in fig. 3 cut by a one-dot chain line IV-IV along the direction D1. Fig. 5 is a cross-sectional view of the pixel region 20 shown in fig. 3 cut by a one-dot chain line V-V along the direction D2. Both fig. 4 and 5 show a structure of an upper layer of the organic insulating film 120 described with reference to fig. 2.

In fig. 4, the ends of the

pixel electrodes

132R and 132G are covered by the bank portions 134. The pixel electrode 132R is a pixel electrode of a pixel emitting red light, and the pixel electrode 132G is a pixel electrode of a pixel emitting green light. The region located inside the opening 136 of the bank 134, that is, a part of the upper surface of each of the pixel electrode 132R and the pixel electrode 132G functions as the light-emitting region 20Ra or the light-emitting region 20 Ga.

The hole transport layer 32 is provided over the light-emitting region 20Ra, the light-emitting region 20Ga, and the bank portion 134. As shown in fig. 4, the hole transport layer 32 of the present embodiment is provided across a plurality of pixels. The hole transport layer 32 is configured with the purpose of efficiently supplying holes injected from the pixel electrode 132R and the pixel electrode 132G to the light emitting layer 138R and the light emitting layer 138G.

A light-emitting layer 138R made of a red-light-emitting organic EL material is provided over the bank 134 in the light-emitting region 20Ra and its periphery. Further, a light-emitting layer 138G made of a green light-emitting organic EL material is provided over the light-emitting region 20Ga and the bank 134 around the light-emitting region. The light-emitting layer 138R and the light-emitting layer 138G in this embodiment are both formed by a vapor deposition method using a vertical vapor deposition apparatus.

An electron transporting layer 36 is provided over the light emitting layer 138R and the light emitting layer 138G. As shown in fig. 4, the electron transport layer 36 of the present embodiment is provided across a plurality of pixels. The electron transport layer 36 is disposed for the purpose of efficiently supplying electrons injected from the common electrode 140 to the light-emitting

layers

138R and 138G.

A common electrode 140 is disposed over the electron transport layer 36. Further, a sealing film 142 is provided over the common electrode 140. Details of the common electrode 140 and the sealing film 142 are as described with reference to fig. 2.

In fig. 4, only the hole transport layer 32 is shown between the pixel electrode 132R and the light-emitting layer 138R (or the pixel electrode 132G and the light-emitting layer 138G), but either or both of the hole injection layer and the electron blocking layer may be arranged. Further, only the electron transport layer 36 is shown between the common electrode 140 and the light-emitting layer 138R (or the light-emitting layer 138G), but either or both of an electron injection layer and a hole blocking layer may be arranged.

As shown in fig. 4, the distance between the light-emitting region 20Ra and the light-emitting region 20Ga in the D1 direction is L1. In the organic EL display device 100 of the present embodiment, since there is a margin for positional displacement of the light-emitting

layers

138R and 138G in the direction D1, the positions of the light-emitting

layers

138R and 138G may be asymmetrical with respect to the light-emitting regions 20Ra and 20Ga, respectively.

For example, in the case of the light-emitting layer 138R shown in fig. 4, the distance d1 between the end of the light-emitting layer 138R and the light-emitting region 20Ra in the direction from the pixel electrode 132R to the pixel electrode 132G is greater than the distance d2 between the end of the light-emitting layer 138R and the light-emitting region 20Ra in the direction from the pixel electrode 132R to the opposite pixel electrode 132G (see fig. 3). The relationship between the distance d1 and the distance d2 is also true for the light-emitting

layers

138G and 138B.

As described above, in the present embodiment, the distance between the light emitting regions (i.e., between the pixels) in the direction D1 is ensured to be larger than that in the direction D2. Therefore, even if the position of the vapor deposition mask is shifted from the pixel electrode due to the deflection of the vapor deposition mask, and the formation position of the light-emitting layer is shifted, the light-emitting layer is not formed across adjacent light-emitting regions. Therefore, formation defects of the light-emitting layer can be prevented when the organic EL material is deposited by the vapor deposition method.

On the other hand, in the D2 direction intersecting the D1 direction, since the problem of positional deviation between the vapor deposition mask and the pixel electrode due to deflection of the vapor deposition mask does not occur, it is not necessary to provide a margin for positional deviation with respect to the light-emitting layer as in the D1 direction described above.

In fig. 5, the ends of the

pixel electrodes

132R and 132B are covered by the bank portions 134. The pixel electrode 132B is a pixel electrode of a pixel emitting blue light. A region located inside the opening 136 of the bank 134, that is, a part of the upper surface of each of the pixel electrode 132R and the pixel electrode 132B functions as the light-emitting region 20Ra or the light-emitting region 20 Ba.

A hole transport layer 32 is provided over the light-emitting region 20Ra, the light-emitting region 20Ba, and the bank portion 134. Further, a light-emitting layer 138R made of a red-light-emitting organic EL material is provided over the light-emitting region 20Ra and the bank portion 134 therearound. A light-emitting layer 138B made of a blue light-emitting organic EL material is provided on the bank portion 134 around the light-emitting region 20 Ba.

An electron transporting layer 36, a common electrode 140, and a sealing film 142 are provided over the light emitting layer 138R and the light emitting layer 138G. Details of the electron transport layer 36, the common electrode 140, and the sealing film 142 are as described using fig. 4.

As shown in fig. 5, the distance between the light-emitting region 20Ra and the light-emitting region 20Ba in the direction D2 is L2, which is smaller than L1 shown in fig. 4. In the organic EL display device 100 of the present embodiment, since it is not necessary to secure a margin for positional displacement of the light-emitting layer 138R and the light-emitting layer 138B in the direction D2, the positions of the light-emitting layer 138R and the light-emitting layer 138B may be symmetrical with respect to the light-emitting region 20Ra and the light-emitting region 20Ba, respectively.

For example, in the case of the light-emitting layer 138R shown in fig. 5, the distance d3 between the end of the light-emitting layer 138R and the light-emitting region 20Ra in the direction from the pixel electrode 132R to the pixel electrode 132B is substantially equal to the distance d4 between the end of the light-emitting layer 138R and the light-emitting region 20Ra in the direction from the pixel electrode 132R to the opposite pixel electrode 132B (see fig. 3). The same applies to the light-emitting

layers

138G and 138B in relation to the distance d3 and the distance d 4.

Here, the relationship between the distances d1 to d4 described with reference to fig. 4 and 5 will be described with reference to fig. 6. Fig. 6 is an enlarged plan view of a part of the pixel region 20 in the organic EL display device 100 according to the first embodiment. In the organic EL display device 100 of the present embodiment, a sub-pixel emitting red light, a sub-pixel emitting green light, and a sub-pixel emitting blue light are combined to function as 1 main pixel.

As shown in fig. 6, a distance L1 between light-emitting regions adjacent in the first direction (D1 direction) (e.g., between the light-emitting region 20Ra and the light-emitting region 20 Ga) is larger than a distance L2 between light-emitting regions adjacent in the second direction (D2 direction) intersecting the first direction (e.g., between the light-emitting region 20Ra and the light-emitting region 20 Ba). Here, the "first direction" refers to a direction substantially perpendicular to the horizontal plane. The "second direction" refers to a direction intersecting the first direction, for example, a direction substantially orthogonal to the first direction.

Further, when attention is paid to the light-emitting region 20Ra in fig. 6, a distance D1 between the light-emitting region 20Ra facing downward in the direction D1 in the drawing and the end of the light-emitting layer 138R is larger than a distance D2 between the light-emitting region 20Ra facing upward in the direction D1 in the drawing and the end of the light-emitting layer 138R.

The distance D3 between the light-emitting region 20Ra facing the right side in the direction of D2 in the drawing and the end of the light-emitting layer 138R is substantially equal to the distance D4 between the light-emitting region 20Ra facing the left side in the direction of D2 in the drawing and the end of the light-emitting layer 138R.

Further, as shown in FIG. 6, distances d 2-d 4 are all less than distance d 1. In this case, the distance d2 may also be designed to be approximately equal to the distance d3 or the distance d 4.

The relationship of the distances d1 to d4 shown in fig. 6 does not necessarily hold for all pixels. As described above, when the vapor deposition mask is set upright in the vertical vapor deposition device, the vicinity of the center of the vapor deposition mask is particularly greatly bent, and thus the position of the opening of the vapor deposition mask and the light emitting region is likely to be shifted. Conversely, if the deflection of the vapor deposition mask is small, the distance d2 may be larger than the distance d1, or the distance d1 may be substantially equal to the distance d 2. However, when a margin for positional displacement of the light-emitting layer is given in the direction of D1 as in the present embodiment, it can be said that a light-emitting region in which the relationship shown in fig. 6 is established exists somewhere in the pixel region 20.

< method for producing organic EL display device >

Next, a method for manufacturing the organic EL display device 100 according to the present embodiment will be described. Fig. 7, 8 and 10 are sectional views showing a manufacturing process of the organic EL display device 100 according to the first embodiment.

First, as shown in fig. 7, the thin film transistor 50 and the storage capacitor 55 are formed on the support substrate 201. The method for forming the thin film transistor 50 and the storage capacitor 55 is not particularly limited, and they can be formed by a known method. As the support substrate 201, a glass substrate is used in the present embodiment, but another insulating substrate may be used.

When a flexible substrate made of a resin material is used as the support substrate 201, a resin film such as polyimide is formed on a support substrate such as a glass substrate, and the thin film transistor 50 and the storage capacitor 55 are formed on the resin film. Finally, after the first sealing film 142a, the second sealing film 142b, and the third sealing film 142c shown in fig. 2 are formed, the resin film may be peeled from the support substrate.

In this embodiment mode, a base film 202 is provided over a support substrate 201, and a semiconductor film 50a is formed thereover. Next, a gate insulating film 50b is formed to cover the semiconductor film 50 a. After the gate insulating film 50b is formed, a gate electrode 50c is formed in a region overlapping with the semiconductor film 50a on the gate insulating film 50 b. The capacitor electrode 50d constituting a part of the storage capacitor 55 is formed simultaneously with the formation of the gate electrode 50 c.

Next, an insulating film 50e is formed so as to cover the gate electrode 50c and the capacitor electrode 50d, and then, a source electrode 50f and a drain electrode 50g are formed so as to be connected to the semiconductor film 50a through a contact hole (not shown) formed in the insulating film 50 e. At this time, the source electrode 50f is formed to overlap the capacitor electrode 50d in a plan view. In this way, the thin film transistor 50 and the storage capacitor 55 are formed on the support substrate 201.

Next, as shown in fig. 8, after the thin film transistor 50 and the storage capacitor 55 are formed, an organic insulating film 120 is formed. In this embodiment, an acrylic resin material having positive photosensitivity is used as a material constituting the organic insulating film 120. More specifically, after an acrylic resin material constituting the organic insulating film 120 is applied, a region where the opening 122 is formed is selectively exposed to light by photolithography and patterned, and an unnecessary acrylic resin material is removed. This enables the organic insulating film 120 having the opening 122 to be formed without performing etching treatment. As shown in fig. 8, the opening 122 is formed to expose a part of the thin film transistor 50 (specifically, the source electrode 50 f).

Next, after the opening 122 is formed, an oxide conductive film 124 made of a metal oxide material such as ITO and a lower electrode 126 of the storage capacitor 57 are formed so as to cover the opening 122. The oxide conductive film 124 and the lower electrode 126 are formed by patterning an oxide conductive film such as ITO formed so as to cover the organic insulating film 120 by photolithography. At this time, the oxide conductive film 124 is electrically connected to the source electrode 50f of the thin film transistor 50. The lower electrode 126 is provided in a region where the organic EL element 60 is formed later.

Next, after the oxide conductive film 124 and the lower electrode 126 are formed, the inorganic insulating film 128 is formed. In this embodiment, a silicon nitride film is formed as the inorganic insulating film 128. Further, an opening 130a for exposing a part of the organic insulating film 120 and an opening 130b for exposing a part of the oxide conductive film 124 are formed in the inorganic insulating film 128. The inorganic insulating film 128 functions as a protective film for preventing moisture generated from the organic insulating film 120 from affecting the organic EL element 60, and also functions as a dielectric constituting the storage capacitor 57.

After forming the opening 130a and the opening 130b in the inorganic insulating film 128, the pixel electrode 132 is formed on the inorganic insulating film 128. The pixel electrode 132 has a laminated structure of an IZO thin film, a silver thin film, and an IZO thin film. The pixel electrode 132 is electrically connected to the oxide conductive film 124 inside the opening 130 b. In other words, the pixel electrode 132 is electrically connected to the thin film transistor 50 through the oxide conductive film 124.

At this time, the region where the organic insulating film 120 is exposed inside the opening 130a functions as the drain region 65 shown in fig. 2. That is, when a process is performed after the opening 130a is formed, the moisture evaporated in the organic insulating film 120 is discharged to the outside through the drain region 65.

Further, by forming the pixel electrode 132, the storage capacitor 57 formed of the lower electrode 126, the inorganic insulating film 128, and the pixel electrode 132 is formed. In this embodiment, although not shown, the storage capacitor 57 is disposed between the gate electrode 50c and the source electrode 50f of the thin film transistor 50 formed of an N-channel transistor. That is, the lower electrode 126 which is one electrode of the storage capacitor 57 is connected to the gate electrode 50 c. The pixel electrode 132, which is the other electrode of the holding capacitor 57, is connected to the source electrode 50 f.

Next, after the pixel electrode 132 is formed, a bank portion 134 made of a resin material is formed. In the present embodiment, a photosensitive acrylic resin material is used as a material constituting the bank portion 134. The bank 134 covers the outer edge of the pixel electrode 132, and is patterned so as to expose a part of the upper surface of the pixel electrode 132. The opening 136 formed by this patterning defines a region (light-emitting region) that functions as the organic EL element 60 on the upper surface of the pixel electrode 132.

After the bank 134 is formed, the light-emitting layer 138 is formed. In this embodiment, the light-emitting layer 138 is formed separately for each pixel by a vapor deposition method using a vertical vapor deposition apparatus. Further, a functional layer such as an electron transport layer or a hole transport layer other than the light-emitting layer 138 may be provided in common to a plurality of pixels. In this embodiment, the light-emitting layer 138 that can be used is not particularly limited, and a known material can be used.

In this embodiment, a vapor deposition mask 90 shown in fig. 9A is used for forming the light-emitting layer 138 by a vapor deposition method. Fig. 9A is a front view showing an example of a vapor deposition mask 90 according to the first embodiment. The vapor deposition mask 90 has a plurality of electroforming masks 90b in a mask frame 90 a. As a material of the mask frame 90a, invar, carbon fiber Reinforced plastic (CFPR), or the like can be used, for example.

In particular, carbon fiber reinforced plastics have a lower linear expansion coefficient and a lower specific gravity than invar and a higher elastic modulus than invar, and therefore are excellent as a material for the mask frame 90 a. That is, by forming the mask frame 90a of carbon fiber reinforced plastic, the deflection of the vapor deposition mask 90 can be reduced as compared with the invar structure. In the case where the mask frame 90a is formed of carbon fiber reinforced plastic, the plating is preferably performed by metal plating. This can reduce the amount of exhaust gas from the carbon fiber reinforced plastic under reduced pressure (for example, during vapor deposition).

Each of the electroforming masks 90b described above corresponds to 1 organic EL display device. In fig. 9A, although the electroforming mask 90b appears to have 1 opening, a plurality of openings 90d, which will be described later, are actually arranged corresponding to the positions of the respective pixels of the organic EL display device.

Fig. 9B is a plan view showing a state where the light-emitting layer 138 (specifically, the light-emitting layer 138R which emits red light) is formed by a vapor deposition method. Fig. 9B shows a state where the vapor deposition mask 90 is not bent.

In the electroforming mask 90b provided in the vapor deposition mask 90 of the present embodiment, a plurality of openings 90d are provided in the metal film 90c formed by electroforming. The opening 90D has a rectangular shape having a long axis in the direction D1. The vapor deposition mask 90 is arranged above the bank 134 shown in fig. 8 so that the openings 90d are aligned with the positions of the light-emitting regions 20 Ra. At this time, as shown in fig. 9B, the vapor deposition mask 90 is disposed so as to face the light-emitting region 20Ra and be positioned below the opening 90 d. In fig. 9B, facing the drawing, the lower direction is the direction in which gravity acts. That is, in the present embodiment, when the vapor deposition mask 90 is disposed, a space in which the deflection of the vapor deposition mask 90 is taken into consideration is previously made above the light-emitting region 20Ra (on the side opposite to the direction in which gravity acts).

Fig. 9C is a plan view showing a state where the light-emitting layer 138 (specifically, the light-emitting layer 138R which emits red light) is formed by the vapor deposition method. Fig. 9C shows a state in which the vapor deposition mask 90 is deflected by its own weight.

As described above, in the present embodiment, when the vapor deposition mask 90 is disposed, a space in which the deflection of the vapor deposition mask 90 is considered is previously made above the light-emitting region 20Ra (on the side opposite to the direction in which gravity acts). Therefore, as shown in fig. 9C, even if the vapor deposition mask 90 is deflected by its own weight to cause a positional deviation of the opening 90d, the light emitting region 20Ra is positioned inside the opening 90 d. Further, since the distance between the light-emitting region 20Ra and the light-emitting region 20Ga (the distance L1 shown in fig. 6) is sufficiently long in the direction D1, it is possible to prevent a formation failure in which the light-emitting layer 138R emitting red light is formed over the light-emitting region 20 Ga.

After the light-emitting layer 138 is formed by the vapor deposition method using the vertical vapor deposition apparatus as described above, the common electrode 140 is formed as shown in fig. 10. In the present embodiment, a conductive film (MgAg film) made of an alloy containing magnesium and silver is used as the common electrode 140. Such a conductive film containing a group 2 element is not resistant to moisture or the like, as in the light-emitting layer 138. Therefore, it is preferable that the evaporation of the light-emitting layer 138 and the evaporation of the common electrode 140 be performed without exposure to the atmosphere. In this case, the vapor deposition process is preferably continuously performed while maintaining vacuum, but the present invention is not limited thereto, and it is also effective to continuously perform the vapor deposition process while maintaining an inert atmosphere such as a nitrogen atmosphere.

At this time, the organic EL element 60 including the pixel electrode 132, the light-emitting layer 138, and the common electrode 140 is formed inside the opening 136 provided in the bank 134.

Next, the first sealing film 142a made of a silicon nitride film, the second sealing film 142b made of a resin material, and the third sealing film 142c made of a silicon nitride film are sequentially stacked to obtain the structure shown in fig. 2. At this time, the second sealing film 142b can flatten undulation caused by the openings 136 formed in the dam portion 134.

Further, even if foreign matter such as particles exists on the common electrode 140, since the second sealing film 142b can flatten undulation, the possibility that the third sealing film 142c formed over the second sealing film 142b peels off or causes poor coverage due to the influence of the foreign matter can be reduced.

(second embodiment)

In this embodiment, an example in which the arrangement of the light emitting regions is different from that in the first embodiment will be described with reference to fig. 11A and 11B. Specifically, in this embodiment, an example in which pixels are arranged in a stripe shape will be described. In this embodiment, the same portions as those of the organic EL display device 100 according to the first embodiment are denoted by the same reference numerals, and description thereof may be omitted.

Fig. 11A and 11B are plan views showing the structure of a pixel in an organic EL display device according to a second embodiment. Specifically, fig. 11A and 11B correspond to a plan view of a state in which the light-emitting layer 138 is formed on a part of the upper surface of the pixel electrode 132 (i.e., the light-emitting region) and the bank 134.

As shown in fig. 11A, in the pixel region 20-1, the light emitting region 20Rb emitting red light, the light emitting region 20Gb emitting green light, and the light emitting region 20Bb emitting blue light are arranged in a stripe shape. A light-emitting layer 138R made of an organic EL material emitting red light, a light-emitting layer 138G made of an organic EL material emitting green light, and a light-emitting layer 138B made of an organic EL material emitting blue light are formed on the light-emitting region 20Rb, the light-emitting region 20Gb, and the light-emitting region 20Bb, respectively.

In this embodiment, as shown in fig. 11A, for example, a distance L1 between the light-emitting regions 20Rb adjacent to each other in the D1 direction is greater than a distance L2 between the light-emitting regions 20Rb and 20Gb adjacent to each other in the D2 direction. Therefore, in the vertical vapor deposition device, as in the first embodiment, even if the vapor deposition mask is deflected by its own weight, the organic EL display device can be formed without causing a defect in the formation of the light-emitting layer.

As shown in fig. 11B, in the pixel region 20-2, the light emitting region 20Rb emitting red light, the light emitting region 20Gb emitting green light, and the light emitting region 20Bb emitting blue light are arranged in a stripe shape. The light emitting regions are arranged in a staggered manner line by line.

In this case, as also shown in fig. 11B, for example, a distance L1 between the light-emitting regions 20Rb adjacent in the D1 direction is larger than a distance L2 between the light-emitting regions 20Rb and 20Gb adjacent in the D2 direction. Therefore, in the vertical vapor deposition device, as in the first embodiment, even if the vapor deposition mask is deflected by its own weight, the organic EL display device can be formed without causing problems such as poor formation of the light-emitting layer and color mixing of the light-emitting colors.

The embodiments described above as embodiments of the present invention can be combined and implemented as appropriate as long as they do not contradict each other. Further, a display device in which addition, deletion, or design change of a component is appropriately performed or a manufacturing method in which addition, deletion, or condition change of a process is performed based on the organic EL display device of each embodiment is appropriately performed by those skilled in the art, and the method is included in the scope of the present invention as long as the gist of the present invention is achieved.

Note that, even if the operation and effect is other than the operation and effect according to the above-described embodiments, the operation and effect which can be clarified by the description of the present specification or which can be easily predicted by a person skilled in the art is of course understood to be the operation and effect according to the present invention.

Description of the reference numerals

20 … pixel region, 20a … pixel, 20Ra, 20Ga, 20Ba, 20Rb, 20Gb, 20Bb … light emitting region, 22 … peripheral region, 24 … terminal region, 26 … flexible printed circuit board, 28 … driving circuit, 50 … thin film transistor, 50a … semiconductor film, 50b … gate insulating film, 50c … gate electrode, 50d … capacitor electrode, 50e … insulating film, 50f … source electrode, 50g … drain electrode, 55, 57 … holding capacitor, 60 … organic EL element, 65 … drain region, 80, 90 … vapor deposition mask, 80a, 90a … mask frame, 80b, 90b … electroforming mask, 80c, 90c … metal film, 80d, 90d … opening, 100 … display device, … array substrate, 120 … organic insulating film, 122 …, 124 b, … oxide opening, …, 36126, 36128 lower electrode, … electrode, 130a, 130B … openings, 132R, 132G, 132B … pixel electrodes, 134 … bank, 134 … openings, 138R, 138G, 138B … light-emitting layers, 140 … common electrodes, 142 … sealing films, 142a … first sealing films, 142B … second sealing films, 142c … third sealing films, 201 … supporting substrates, 202 … base films.

Claims

1. An organic EL display device, comprising:

a plurality of pixel electrodes;

an organic insulating layer provided over the plurality of pixel electrodes and having an opening at a position overlapping with a part of an upper surface of each of the plurality of pixel electrodes in a plan view;

a light-emitting layer covering the opening; and

a common electrode disposed over the light emitting layer, disposed across the plurality of pixel electrodes,

when a region of the pixel electrode located inside the opening is defined as a light-emitting region in a plan view, a distance L1 between the light-emitting regions adjacent in a first direction is greater than a distance L2 between the light-emitting regions adjacent in a second direction intersecting the first direction.

2. The organic EL display device according to claim 1, wherein:

the plurality of pixel electrodes include: a first pixel electrode; a second pixel electrode adjacent to the first pixel electrode in the first direction; a third pixel electrode adjacent to the first pixel electrode on a side of the first pixel electrode opposite to the second pixel electrode,

the light emitting layer includes a first light emitting layer opposite to the first pixel electrode and overlapping the organic insulating layer,

in a plan view, a distance d1 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the second pixel electrode is greater than a distance d2 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the third pixel electrode.

3. An organic EL display device, comprising:

a plurality of pixel electrodes;

a light-emitting layer covering the opening; and

when a region of the pixel electrode located inside the opening is a light-emitting region in a plan view, a distance d1 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the second pixel electrode is greater than a distance d2 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the third pixel electrode.

4. The organic EL display device according to claim 2 or 3, wherein:

the plurality of pixel electrodes further includes: a fourth pixel electrode adjacent to the first pixel electrode in a second direction crossing the first direction; and a fifth pixel electrode adjacent to the first pixel electrode on a side of the first pixel electrode opposite to the fourth pixel electrode,

in a plan view, a distance d3 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the fourth pixel electrode and a distance d4 between the light-emitting region of the first pixel electrode and an end of the first light-emitting layer in a direction from the first pixel electrode toward the fifth pixel electrode are smaller than the distance d 1.

5. The organic EL display device according to claim 4, wherein:

the distance d3 is substantially equal to the distance d4 in a top view.

6. The organic EL display device according to claim 4, wherein:

the distance d3 and the distance d4 are substantially equal to the distance d2 in a top view.

7. The organic EL display device according to claim 2, wherein:

the first light-emitting layer has a light-emitting color different from a light-emitting color of a light-emitting layer provided over the second pixel electrode or the third pixel electrode.

8. An organic EL display device according to claim 3, wherein:

9. The organic EL display device according to claim 4, wherein:

the first light-emitting layer has a light-emitting color different from a light-emitting color of a light-emitting layer provided over the fourth pixel electrode or the fifth pixel electrode.

10. The organic EL display device according to claim 2, wherein:

the light emitting layer provided over the second pixel electrode emits light of the same color as the light emitting layer provided over the third pixel electrode.

11. An organic EL display device according to claim 3, wherein:

12. The organic EL display device according to claim 4, wherein:

the light emitting layer provided over the fourth pixel electrode emits light of the same color as the light emitting layer provided over the fifth pixel electrode.