WO2010113312A1 - Display device - Google Patents

Abstract

Disclosed is a display device having high reliability, wherein thermal energy during recovery of contact resistance of an electrode, thermal energy generated due to leakage, and damage to the device are reduced. Specifically disclosed is a display device wherein a first electrode, an organic functional layer and a second electrode are formed on a substrate in this order, and a third electrode connected with an end of the second electrode is also formed on the substrate. The display device is characterized in that a relaxation layer is partially formed in at least one of the following positions: (i) below the third electrode and above the second electrode in such a manner that the portion at which the second electrode and the third electrode are connected with each other is covered; or (ii) below the first electrode and above the second electrode in such a manner that the portion at which the first electrode and the second electrode intersect each other is covered.

Description

Display device

The present invention relates to a display device used for an organic EL display or the like.

In recent years, the structure of a display device used in various fields ranging from a small mobile phone to a large television exceeding 100 inches has an anode, an organic functional layer, and a cathode sequentially formed on a substrate. In this structure, a lead electrode connected to the end of the electrode is formed.

However, in the display device having such a structure, (1) an oxide film is formed on the extraction electrode by plasma treatment, UV treatment, wet treatment, etc. performed before forming the organic functional layer, etc. This oxide film raises the problem that the contact resistance of the electrode increases and the drive voltage becomes high, and (2) the problem that the thermal energy generated by the leakage damages the display device.

Here, in contrast to (1), an invention has been developed in which the surface of the extraction electrode with increased contact resistance is irradiated with a laser in advance to remove the oxide film (see Patent Document 1). In contrast to (2), in order to prevent cracks due to thermal history, an invention having a relaxation layer around the electrode has been developed (see Patent Document 2).

JP 2006-294421 A JP 2007-41203 A

However, in the invention described in Patent Document 1, it is effective for removing an oxide film that causes an increase in contact resistance. However, since the organic functional layer is formed after the removal by laser, particles produced by the oxide film removing process are used. Oxidation and re-oxidation occur in the cleaning process after removal. Furthermore, in the invention described in Patent Document 2, a relaxation layer is used around the electrode to prevent thermal history. However, when thermal energy is generated due to leakage, there is no relaxation layer directly below or directly above the electrode, so that the display device has The problem of damaging it remained.

The present invention has been made in view of such a problem, and reduces the thermal energy when recovering the contact resistance of the electrode, thermal energy generated by leakage, and damage to the device, thereby providing a highly reliable display. The main challenge is to provide devices.

In the display device of the present invention for solving the above-described problem, a first electrode, an organic functional layer, and a second electrode are formed in this order on a substrate, and an end portion of the second electrode In the display device in which the connected third electrode is formed on the substrate, the second electrode and the second electrode are covered under the third electrode so as to cover a portion where the second electrode and the third electrode are connected. A relaxation layer is partially formed on at least one of the top or the second electrode and the second electrode so as to cover a portion where the first electrode and the second electrode intersect with each other. It is characterized by.

It is a schematic sectional drawing which shows the display device of this application.

Embodiments of the display device of the present application will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a display device.

As shown in FIG. 1, in the display device, a first electrode 2, an organic functional layer 3, and a second electrode 5 are formed on a substrate 1 in this order, and an end portion of the second electrode 5 is formed. The third electrode 6 connected to is formed on the substrate.

Here, the part where the second electrode and the third electrode are connected is covered under the third electrode, above the second electrode, and the part where the first electrode and the second electrode intersect. As described above, a relaxing layer is formed below the first electrode and above the second electrode.

Hereinafter, the configuration of each layer of the display device of the present application will be described in detail.

(Substrate 1)
As the substrate 1, a substrate conventionally used as a substrate of a display device can be used, and is not particularly limited. For example, the transparent substrate itself may be used, or a color conversion filter having a color modulation unit provided on the transparent substrate may be used. Alternatively, it may be a flexible film formed from polyolefin, acrylic resin (including polymethyl methacrylate), polyester resin (including polyethylene terephthalate), polycarbonate resin, polyimide resin, or the like. Or the board | substrate with which TFT which drives an EL element was arrange | positioned may be sufficient.

Alternatively, a substrate passivation layer (SiO _x , SiN _x , SiN _x O _y , which bears a part of the function of blocking oxygen and / or moisture between the substrate and the first electrode to be described next, Insulating inorganic oxides such as AlO _x , TiO _x , TaO _x , and ZnO _x , inorganic nitrides, inorganic oxynitrides, and the like may be used.

The thickness of the substrate 1 is not particularly limited, but may be 100 μm to 2000 μm.

(First electrode 2)
The first electrode 2 is formed on the substrate 1, but it may be formed on the transparent substrate itself, or may be formed on the transparent substrate / substrate passivation layer. In general, the substrate is composed of a plurality of partial electrodes.

Examples of the method for forming the first electrode 2 include photolithography patterning, sputtering, and vacuum deposition. For example, a conductive metal oxide such as SnO ₂ , In ₂ O ₃ , ITO, indium / zinc oxide (IZO), aluminum-doped zinc oxide (ZnO: Al) is deposited on the substrate 1 by sputtering. Is formed.

The thickness of the first electrode 2 is not particularly limited, but may be 10 nm to 1000 nm.

Each of the plurality of partial electrodes constituting the first electrode 2 can have, for example, a stripe shape extending in the first direction. Then, passive matrix driving can be performed by further forming second electrodes 5 to be described later as a plurality of striped electrodes extending in a second direction intersecting (preferably orthogonally intersecting) the first direction. It can be configured as follows.

(Organic functional layer 3)
The organic functional layer 3 is formed between the first electrode 2 and the second electrode 5.

The organic functional layer 3 includes at least an organic light emitting layer, and includes a hole transport layer, a hole injection layer, an electron transport layer, and / or an electron injection layer as necessary. Each of these layers is formed to have a film thickness sufficient to realize desired characteristics in each layer. For example, what consists of the following layer structures is employ | adopted.
(1) Organic light emitting layer (2) Hole injection layer / organic light emitting layer (3) Organic light emitting layer / electron injection layer (4) Hole injection layer / organic light emitting layer / electron injection layer (5) Hole transport layer / Organic light emitting layer / electron injection layer (6) hole transport layer / organic light emitting layer / electron transport layer (7) hole injection layer / hole transport layer / organic light emitting layer / electron injection layer (8) hole injection layer / Hole transport layer / organic light emitting layer / electron transport layer (9) hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer (in the above configuration, the electrode functioning as the anode is on the left side) Connected and the electrode functioning as the cathode is connected to the right side)
Any known material can be used as the material of the organic light emitting layer. For example, in order to obtain light emission from blue to blue-green, for example, a condensed aromatic ring compound, a ring assembly compound, a metal complex (such as an aluminum complex such as [tris- (8-hydroxyquinoline) aluminum] (Alq ₃ )), Styrylbenzene compounds [4,4'-bis (diphenylvinyl) biphenyl (DPVBi), etc.], porphyrin compounds, benzothiazole, benzimidazole, benzoxazole, and other fluorescent brighteners, aromatic dimethylidines Materials such as compounds are preferably used. Or you may form the organic light emitting layer which emits the light of a various wavelength range by adding a dopant to a host compound. As the host compound, a distyrylarylene compound (for example, IDE-120 manufactured by Idemitsu Kosan Co., Ltd.), N, N′-ditolyl-N, N′-diphenylbiphenylamine (TPD), Alq ₃ or the like can be used. As dopants, perylene (blue violet), coumarin 6 (blue), quinacridone compounds (blue green to green), rubrene (yellow), 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6-methyl- 4H-pyran (DCM, red), platinum octaethylporphyrin complex (PtOEP, red), or the like can be used.

As the material for the hole injection layer, phthalocyanines (including Pc, CuPc, etc.) or indanthrene compounds can be used. The hole transport layer can be formed using a material having a triarylamine partial structure, a carbazole partial structure, or an oxadiazole partial structure. The material that can be used is preferably TPD, N, N′-bis (naphthalen-1-yl) -N, N′-bis (phenyl) benzidine (α-NPD), 1,3,5-tris { 4- [methylphenyl (phenyl) amino] phenyl} benzene (MTDAPB, o-, m-, p-), 4,4 ', 4 "-tris [N-3-methylphenyl-N-phenylamino] triphenyl Amine (m-MTDATA) and the like.

Materials for the electron transport layer include aluminum complexes such as Alq ₃ ; 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxathiazole (PBD), 1, Oxadiazole derivatives such as 3,5-tris [5- (4-tert-butylphenyl) -1,3,4-oxathiazol-2-yl] benzene (TPOB); triazole (TAZ) and other triazole derivatives; Use of a triazine derivative having the basic skeleton of the structural formula (I) shown below; phenylquinoxalines; thiophene derivatives such as 5,5′-bis (dimesitylboryl) -2,2′-bithiophene (BMB-2T) Can do. As the material for the electron injection layer, an aluminum complex such as Alq ₃ or an aluminum quinolinol complex doped with an alkali metal or an alkaline earth metal can be used.

The formation method of each layer constituting the organic functional layer 3 is formed by using any means known in the art such as a vacuum deposition method such as a spin coating method, a spray method, a wet method such as an inkjet method, or the like. be able to.

(Insulating film 4)
The insulating film 4 is provided arbitrarily, and is provided between the first electrode 2 and the second electrode 5 and applied to a portion where the light emitting element is not formed (non-light emitting element portion), and a portion where the light emitting element is formed (light emitting) A pattern is formed on the entire substrate so that the element portion or the pixel portion) is an opening.

The thickness of the insulating film 4 is not particularly limited, but is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 3 μm, from the viewpoint of preventing dielectric breakdown between the counter electrodes and leakage current. When an organic EL layer and a second electrode are further formed on this film, it is possible to energize only the patterned openings, and light emission can be obtained only in those portions.

The material of the insulating film 4 includes inorganic oxides such as SiO _x , SiN _x , SiN _x O _y , AlO _x , TiO _x , TaO _x , ZnO _{x and the} like, inorganic nitrides and inorganic oxynitrides, and organic substances Includes a polymer material such as a resist material and polyimide.

The formation method of the insulating film 4 is known in the art such as vapor deposition (resistance heating or electron beam heating), sputtering, ion plating, laser ablation in the case of inorganic materials, and spin coating method, casting method, etc. in the case of organic materials. It can be formed using any means. For the patterning of the insulating film 4, any means known in the art such as photo etching, dry etching, lift-off method can be used.

(Second electrode 5)
The second electrode 5 is composed of a plurality of partial electrodes, and is preferably formed using a highly reflective metal, amorphous alloy, or microcrystalline alloy. High reflectivity metals include Al, Ag, Mo, W, Ni, Cr, and the like. High reflectivity amorphous alloys include NiP, NiB, CrP, CrB, and the like. The highly reflective microcrystalline alloy includes NiAl and the like.

The formation method of the second electrode 5 may include any means known in the art such as vapor deposition (resistance heating or electron beam heating), sputtering, ion plating, laser ablation, etc., depending on the material used. it can. The second electrode 5 made up of a plurality of partial electrodes may be formed using a mask that gives a desired shape, or the second electrode 5 made up of a plurality of partial electrodes using a separating partition having a reverse tapered cross-sectional shape. The electrode 5 may be formed.

The thickness of the second electrode 5 is not particularly limited, but may be 10 nm to 1000 nm.

Each of the plurality of partial electrodes constituting the second electrode 5 may have a stripe shape extending in the second direction, for example. Here, the first direction related to the first electrode 2 and the above-described second direction are preferably crossed, more preferably orthogonal. By adopting such a configuration, by applying an electric field to one of the partial electrodes constituting the first electrode 2 and one of the partial electrodes constituting the second electrode 5, Passive matrix driving in which the light emitting layer emits light can be performed.

(Third electrode 6)
The third electrode 6 is connected to the end of the second electrode 5 and serves as a connection terminal with an external drive circuit.

The material of the third electrode 6 is not particularly limited, but a material having low electrical resistivity and excellent productivity and stability is preferable, and a simple substance selected from the group consisting of aluminum, molybdenum, nickel, tungsten, or chromium, or those An alloy containing

The third electrode 6 can be formed by vapor deposition or sputtering.

The thickness of the third electrode 6 is not particularly limited, but is preferably 100 nm to 10 μm, more preferably 200 nm to 1 μm from the viewpoint of electrical contact.

Also, examples of a method for reducing the contact resistance between the second electrode and the third electrode include laser irradiation with a laser beam, voltage application, and the like. As the laser beam, it is preferable to use an excimer laser capable of finely processing a nanoscale metal thin film. Using these methods, by applying thermal energy to the second electrode and the third electrode, the second electrode and the third electrode are changed in shape, and the contact resistance is lowered.

(Relaxation layers 11-14)
As shown in FIG. 1, under the third electrode 6 and the second electrode 5 or the first electrode 2 and the second electrode so as to cover a portion where the second electrode 5 and the third electrode 6 are connected. 5 is characterized in that a relaxation layer is partially formed on at least one of the lower side of the first electrode 2 and the upper side of the second electrode 5 so as to cover a portion where the crossing point 5 intersects. In addition, the first electrode 2 and the second electrode 5 are provided under the third electrode 6, the second electrode 5, and the first electrode 2 and the second electrode 5 so as to cover a portion where the second electrode 5 and the third electrode 6 are connected. The case where the relaxation layer is partially formed below the first electrode 2 and the second electrode 5 so as to cover the intersecting portion will be described below. At this time, for ease of explanation below, the relaxation layer formed below the third electrode 6 is the first relaxation layer 11, the relaxation layer formed above the second electrode 5 is the second relaxation layer 12, and the first The relaxation layer formed under the electrode 2 will be described as a third relaxation layer 13, and the relaxation layer formed over the second electrode 5 will be described as a fourth relaxation layer 14.

First, as shown in FIG. 1, on the first relaxing layer 2 below the third electrode 6 and on the second electrode 5 so as to cover the portion where the second electrode 5 and the third electrode 6 are connected. The second relaxation layer is characterized in that it is partially formed.

The first relaxing layer 11 is formed under the third electrode 6, but the first relaxing layer 11 is formed only (partially) at a portion where the second electrode 5 and the third electrode 6 are connected. Is preferred.

As a result, even if moisture or the like enters from the substrate side, it can be prevented that it spreads through the relaxation layer and spreads all over other layers.

The thermal conductivity of the first relaxation layer 11 is not particularly limited, but may be 1/10 or less of the thermal conductivity of each of the first, second, and third electrodes. Specifically, if the thermal conductivity of the first, second, and third electrodes is about 100, the thermal conductivity of the first relaxing layer 11 is preferably 0.1 to 10. As a result, heat can be diffused through the electrodes without transmitting thermal damage from the top to the bottom in the drawing.

The material of the first relaxing layer 11 is not particularly limited, but may be a resin material. In particular, it may be a polyimide resin, an acrylic resin, a fluorene resin, or a novolac resin.

The thickness of the first relaxing layer 11 is not particularly limited, but may be 10 nm to 5000 nm. If the thickness is too thin, even if the thermal conductivity is low as described above, thermal damage is transmitted to each layer, and thus the above-described thickness is preferable.

Examples of the method of forming the first relaxing layer 11 include a photolithographic patterning method, an ink jet method, a CVD method, and a vapor deposition method.

The thermal conductivity, material, and thickness of the second relaxation layer 12 are the same as those of the first relaxation layer.

The second relaxing layer 12 is formed on the second electrode 5, but the second relaxing layer 12 is not formed on the entire surface of the second electrode 5, but the second electrode 5 and the third electrode 6 are formed. It is preferable that it is formed only (partially) at the part to be connected.

Thereby, even if moisture or the like enters from the upper direction (outside) of the second relaxing layer 12, it can be prevented that it spreads through the relaxing layer to the entire other layers.

Examples of the method of forming the second relaxing layer 12 include an ink jet method, a vapor deposition method, and a CVD method.

Thus, the first relaxation layer under the third electrode 6 and the second relaxation layer over the second electrode 5 so as to cover the portion where the second electrode 5 and the third electrode 6 are connected, Is partially formed, it is possible to reduce damage to the display device due to thermal energy even when the surface of the third electrode with increased contact resistance is irradiated with laser to reduce the contact resistance.

Next, a third relaxation layer 13 under the first electrode 2 and a fourth relaxation layer 14 over the second electrode 5 so as to cover a portion where the first electrode 2 and the second electrode 5 intersect. , Is formed.

The third relaxing layer 13 is formed below the first electrode 2, but the third relaxing layer 13 is not formed on the entire surface of the substrate 1, but the first electrode 2 and the second electrode 5 intersect each other. It is preferable that it is formed only (partially). Specifically, it is preferably larger than the width of the first electrode 2. Specifically, it is preferably about 1 μm to 100 μm larger than the width of the first electrode 2.

Thereby, even if moisture or the like enters from the first electrode side, it can be prevented from spreading through the relaxing layer to other layers.

The thermal conductivity of the third relaxation layer 13 is not particularly limited, but may be 1/10 or less of the thermal conductivity of the first, second, and third electrodes. Specifically, assuming that the thermal conductivity of the first, second, and third electrodes is 100, the thermal conductivity of the third relaxing layer 13 is preferably 0.1 to 10.

The material of the third relaxation layer 13 is not particularly limited, but may be a resin material. In particular, it may be a polyimide resin, an acrylic resin, a fluorene resin, or a novolac resin.

The thickness of the third relaxing layer 13 is not particularly limited, but may be 10 nm to 5000 nm.

Examples of the method of forming the third relaxation layer 13 include a photolithographic patterning method, an ink jet method, a CVD method, and a vapor deposition method.

When extracting light from the substrate 1 side, the third relaxation layer may have an average transmittance of 80% or more in the visible light region.

The thermal conductivity, material, and thickness of the fourth relaxation layer 14 are the same as those of the third relaxation layer.

The fourth relaxation layer 14 is formed on the second electrode 5, but the fourth relaxation layer 14 is not formed on the entire surface of the second electrode 5, but the first electrode 2, the second electrode 5, Is preferably formed only (partially) at the intersection. Specifically, the width is preferably larger than the width of the organic functional layer 3 (light emitting portion). Specifically, it is preferably about 1 μm to 100 μm larger than the width of the organic functional layer 3 (light emitting portion).

Thus, even if moisture or the like enters from above (outside) the fourth relaxation layer, it can be prevented from spreading to other layers through the relaxation layer.

Examples of the method of forming the fourth relaxation layer 14 include an inkjet method, a vapor deposition method, and a CVD method.

When extracting light from the side opposite to the substrate 1, the fourth relaxation layer 14 may have an average transmittance of 80% or more in the visible light region.

In this way, by forming a relaxation layer so as to cover the intersection of the first electrode and the second electrode, even if thermal energy is generated due to leakage, a relaxation layer is formed immediately below and immediately above the electrode. Therefore, damage to the display device due to thermal energy can be reduced.

The relaxation layer has a first relaxation layer under the third electrode, a second relaxation layer above the second electrode, and a first electrode so as to cover a portion where the second electrode and the third electrode are connected. The case where the third relaxation layer is formed under the first electrode and the fourth relaxation layer is formed over the second electrode so as to cover the portion where the second electrode and the second electrode cross each other, When the first electrode is formed only on the second relaxing layer above the second electrode and on the second electrode so as to cover the portion where the second electrode and the third electrode are connected, Even if the third relaxation layer is formed under the first electrode and the fourth relaxation layer is formed on the second electrode so as to cover the portion where the second electrode intersects, the effect is obtained. . Further, in the present embodiment, the present invention is described in the passive matrix method, but the same effect can be obtained in the active matrix method.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... 1st electrode 3 ... Organic functional layer 4 ... Insulating layer 5 ... 2nd electrode 6 ... 3rd electrode 10 ... Display device 11 ... 1st 1st relaxation layer 12 ... 2nd relaxation layer 13 ... 3rd relaxation layer 14 ... 4th relaxation layer

Claims (5)

A first electrode, an organic functional layer, and a second electrode are formed on the substrate in this order, and a third electrode connected to an end of the second electrode is formed on the substrate. Display device
A portion under the third electrode and the second electrode, or a portion where the first electrode and the second electrode intersect so as to cover a portion where the second electrode and the third electrode are connected. A display device, wherein a relaxation layer is partially formed on at least one of the first electrode and the second electrode so as to cover the display device. The display device according to claim 1.
A thermal conductivity of the relaxation layer is 1/10 or less of each thermal conductivity of the first electrode, the second electrode, and the third electrode. The display device according to claim 1 or 2,
The display device, wherein the relaxation layer is formed of a resin material. The display device according to any one of claims 1 to 3,
A display device, wherein the thickness of the relaxation layer is 10 to 5000 nm. The display device according to any one of claims 1 to 4,
When extracting light from the side opposite to the substrate, the relaxation layer on the second electrode has an average transmittance of 80% or more in the visible light region,
When light is extracted from the substrate side, the relaxation layer under the first electrode has an average transmittance of 80% or more in the visible light region.

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