JP2008041255A - Organic electroluminescent element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element 100 and the organic EL element, wherein the organic EL element 100 is formed by adhering an organic EL element base material 10 including a plurality of light emitting regions having a first electrode 21, a function layer 31 including a light emitting layer, and a second electrode 41 formed on a substrate 11, and barrier ribs 51, and a sealing base material 70 with an adhering layer 72 formed thereon, the adhesion of the organic EL element substrate 11 and the sealing base material 71 is improved, and an influence of water penetrating from an end is suppressed for a long period of time. <P>SOLUTION: Before a process for adhering the organic EL element base material 10 and the sealing base material 70, surface cleaning treatment including at least UV ozone treatment and plasma treatment is applied to the organic EL element base material 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element (hereinafter referred to as an organic EL element) that is expected to be widely used as a display such as an information display terminal or a surface-emitting light source, and a manufacturing method thereof.

2. Description of the Related Art Conventionally, a display using an electroluminescence (hereinafter simply referred to as EL) display device has been developed for a display unit of a mobile device such as a mobile phone or a PDA, or a personal computer.
An EL display device includes a plurality of light emitting units having an EL layer (light emitting layer) in a substrate surface, and performs desired display by independently driving each light emitting unit.

An organic EL element has a structure in which an organic light emitting medium layer is sandwiched between two electrodes (anode and cathode), one of which has translucency. A self-luminous display element that emits light in a layer.
The organic light emitting medium layer is usually composed of a plurality of layers separated in function, and typical examples thereof include copper phthalocyanine for the hole injection layer and N, N′-di (1-naphthyl) for the hole transport layer. -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine, low molecular EL element in which tris (8-quinolinol) aluminum is laminated on the phosphor layer, and polythiophene in the hole transport layer There is a polymer EL element in which a polyalkylfluorene derivative is laminated on a derivative and a light emitting layer.

  It is known that an organic EL element is deteriorated by moisture and oxygen in the atmosphere when the light emitting medium layer and the cathode layer are left exposed to the atmosphere. As a specific representative example, there is a phenomenon in which a non-light emitting region called a dark spot occurs and expands with time. In order to block the organic EL element from the outside air, a method of covering and sealing the organic EL element with a metal or glass sealing substrate under a dry nitrogen atmosphere via an adhesive has been proposed (for example, Patent Document 1). However, even if an adhesive is used, the element deteriorates due to moisture that has passed through the adhesive and the interface of the organic EL element substrate / adhesive / sealing substrate.

  Therefore, in order to extend the sealing life, the adhesive is required to have low moisture permeability and high adhesion. In order to improve the adhesion between the organic EL element substrate and the sealing substrate, the sealing substrate is subjected to a surface cleaning treatment including UV ozone treatment, corona treatment, plasma treatment and the like. The organic EL element substrate is also subjected to the surface cleaning treatment as described above after forming the hole injection electrode. This is because if the surface of the hole injection electrode is contaminated, the hole injection efficiency for the organic layer formed thereafter is lowered, the light emission efficiency is lowered, a dark spot is generated, or this is enlarged. Moreover, when the joint surface with a sealing base material is dirty, adhesion | attachment of an organic EL element substrate and a sealing base material will become weak. For this reason, it is desirable that the organic EL element substrate and the sealing base material are bonded together immediately after being subjected to a surface cleaning treatment. However, in the case of a polymer EL element, a drying process is indispensable because the element is manufactured by a wet method, and a time from surface treatment to bonding of the organic EL element substrate is particularly required. As a result, the adhesiveness at the interface between the organic EL element substrate and the adhesive is inferior, and is easily peeled off.

The known literature is described below.
JP-A-5-36475

  The present invention has been devised in view of the above problems, and improves the adhesion between an organic EL element substrate and a sealing substrate, and suppresses the influence of moisture entering from the end portion over a long period of time. An object is to provide an organic EL element.

In order to achieve the above object, according to the first aspect of the present invention, in claim 1, a plurality of light emitting regions including a first electrode, a functional layer including a light emitting layer, and a second electrode, and a plurality of partition walls are formed on the substrate. A method for producing an organic electroluminescent element, comprising an organic electroluminescent element substrate and a sealing substrate on which an adhesive layer is formed, wherein the organic electroluminescent element substrate and the sealing substrate are bonded together Before the process, the organic electroluminescence element substrate is subjected to a surface cleaning treatment comprising at least UV ozone treatment and plasma treatment, and the method for producing an organic electroluminescence element is provided.
Moreover, in Claim 2, all the light emission area | regions of this organic electroluminescent element base material are covered with the dry sheet, It is set as the manufacturing method of the organic electroluminescent element of Claim 1 characterized by the above-mentioned. is there.

  According to a third aspect of the present invention, there is provided an organic electroluminescent element manufactured using the method for manufacturing an organic electroluminescent element according to the first or second aspect.

  In the method for producing an organic EL element and the organic EL element of the present invention, the surface treatment of the organic EL element substrate is performed immediately before the organic EL element substrate and the sealing substrate are bonded together. The surface on the material becomes highly active again, the adhesion between the organic EL element substrate and the adhesive is improved, and the influence of moisture entering from the end can be suppressed over a long period of time. Furthermore, since the light emitting region of the organic EL element material is entirely covered with a dry sheet during the surface treatment, there is almost no element deterioration due to UV light, oxygen, plasma, or the like.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a partial cross-sectional schematic sectional view showing an embodiment of the organic EL device of the present invention. 1A shows the organic EL element 100, and FIG. 1B shows the organic EL element substrate 10. The first electrode 21, the functional layer 31 including the light emitting layer, the second electrode 41, and the like are formed on the substrate 11. A light-emitting portion, a partition wall 51, and a dry sheet 61 that adsorbs or removes moisture are formed so as to cover all the light-emitting portions. FIG. 1C shows a sealing substrate 70, and an adhesive layer 72 is formed on the edge of the sealing plate 71. The organic EL element substrate 10 and the sealing substrate 70 are bonded to obtain the organic EL element 100.

Hereinafter, a method for producing the organic EL element substrate 10 will be described.
First, a metal complex oxide such as ITO (indium tin complex oxide), indium zinc complex oxide, zinc aluminum complex oxide, or a metal material such as gold or platinum is deposited on the substrate 11 by resistance heating vapor deposition, electron beam Fine particles formed by patterning with a dry film formation method such as vapor deposition, reactive vapor deposition, ion plating, or sputtering, or fine particles of metal oxide or metal material dispersed in epoxy resin or acrylic resin The first electrode 21 is formed by pattern-printing the dispersion using a wet film formation method such as a gravure printing method or a screen printing method.

The substrate 11 is made of a transparent substrate such as glass, quartz, or a plastic sheet, a metal foil or sheet such as aluminum or stainless steel, a silicon substrate, or a metal such as aluminum, copper, nickel, or stainless steel on the plastic film or sheet. A non-light-transmitting substrate having a laminated film can be used.
Further, a thin film transistor (TFT) may be formed on the substrate 11 as necessary, and used as a driving substrate. As a material of the TFT, an organic TFT such as polythiophene, polyaniline, copper phthalocyanine, or perylene derivative may be used, or amorphous silicon or polysilicon TFT may be used.

  If the first electrode is contaminated during the formation of the functional layer 31 after the first electrode is formed, the hole injection efficiency for the functional layer 31 formed thereafter is lowered, the light emission efficiency is lowered, or a non-dark spot is called. A light emitting area is generated or enlarged. Therefore, substrate cleaning processing such as UV ozone processing, corona processing, and plasma processing is performed. Further, if the organic EL element substrate 10 after the first electrode is formed is dirty, the adhesion with the sealing substrate 70 is deteriorated. Cleaning is preferably performed until the contact angle of the surface becomes 10 ° or less. More preferably, it is 5 ° or less. The shorter the time until the functional layer 31 is formed, the better, preferably within 60 minutes, more preferably within 30 minutes.

  In addition, the contact angle of the surface with respect to a sealing base material is an angle which the sealing base material surface and water make.

  Next, a photosensitive resin solution based on acrylic resin or polyimide resin is applied onto the substrate 11 on which the first electrode 21 is formed using a coating method such as roll coating, spin coating, screen printing, spray coating, or the like. A thick photosensitive layer is formed, and patterning processing such as pattern exposure and development is performed to form partition walls 51 at predetermined positions between the first electrodes 21. Here, the height of the partition wall 51 is around 1 μm.

Next, the functional layer 31 is formed by forming a single layer film or a multilayer film containing a light emitting substance.
As a configuration example when the functional layer 31 is formed of a multilayer film, a hole injection transport layer, an electron transport light emitting layer or a hole transport light emitting layer, a two-layer structure including an electron transport layer, a hole injection transport layer, A three-layer structure comprising a light emitting layer and an electron injecting and transporting layer, and further, it is possible to form a multilayer by separating the injecting layer and the transporting layer, or inserting an electron blocking layer, a hole blocking layer, etc. .

Further, the second electrode 41 is formed on the functional layer 31.
As the material of the second electrode 41, a substance having a high electron injection efficiency into the functional layer 31 is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface in contact with the functional layer, and Al or Cu having high stability and conductivity is laminated. May be used. Further, in order to achieve both electron injection efficiency and stability, one or more kinds of metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, An alloy system with a metal element such as Al or Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used. When the second electrode 41 is used as a translucent electrode layer, a thin work piece of Li or Ca having a low work function is provided, and then ITO (indium tin composite oxide), indium zinc composite oxide, or zinc aluminum composite oxide is used. A metal complex oxide such as ITO may be laminated, and the functional layer 31 may be doped with a small amount of a metal such as Li or Ca having a low work function, and a metal oxide such as ITO may be laminated.

  As a method for forming the second electrode 41, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. The thickness of the second electrode 41 is not particularly limited, but is preferably about 10 nm to 1000 nm. Moreover, when using the 2nd electrode 41 as a translucent electrode layer, about 0.1-10 nm is desirable for the film thickness in the case of using metal materials, such as Ca and Li.

Further, after forming the second electrode, a dry sheet 61 is pasted so as to cover all the light emitting portions. The dry sheet 61 is a laminated sheet in which a hygroscopic substance is kneaded into a double-sided adhesive tape and a binder. The hygroscopic substance is not particularly limited as long as it does not easily react with the fixing organic compound or the like. For example, calcium hydride (CaH ₂ ), strontium hydride (SrH ₂ ), Barium hydride (BaH ₂ ), lithium aluminum hydride (AlLiH ₄ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), calcium oxide (CaO), barium oxide (BaO), magnesium oxide (MgO) Etc. can be mentioned. Specifically, a desiccant-A manufactured by Japan Gore-Tex, a dried sheet commercially available from Dynic HD, and the like can be used. The thickness is desirably at least 500 μm. The step of attaching the dry sheet needs to be performed in a vacuum or in an inert gas atmosphere.

  Further, the substrate surface is cleaned with respect to the organic EL element substrate after the dry sheet is formed. Depending on the situation, a UV ozone treatment method or a plasma treatment method can be used. It is desirable that the substrate cleaning effect be performed until the contact angle of the portion corresponding to the close contact portion with the sealing substrate becomes 10 ° or less again. More preferably, it is 5 ° or less.

Hereinafter, a method for producing the sealing substrate 70 will be described.
The material of the sealing plate 71 is not particularly limited as long as the sealing plate maintains an airtight state and has a predetermined strength. As a material used for the sealing plate, for example, an inorganic material such as a glass plate such as soda lime glass, lead alkali glass, borosilicate glass, aluminosilicate glass, or silica glass, or a metal can be used.

  Next, as a material for forming the adhesive layer 72, radical adhesives using resins such as acrylates such as ester acrylate, urethane acrylate, epoxy acrylate, melamine acrylate, and acrylic resin acrylate, urethane polyester, epoxy, vinyl ether, etc. A photo-curing resin such as a cationic adhesive using a resin, a thiol / ene addition resin-based adhesive, or a thermosetting resin can be used. In order to remove moisture contained in the adhesive layer 72, a desiccant such as barium oxide or calcium oxide may be mixed, or an inorganic filler of about several percent may be mixed in order to control the thickness of the adhesive layer. As a method for forming the adhesive layer 72, it can be formed by a conventionally performed method, and for example, an inkjet method, a dispenser method, or the like can be used. The formation location of the adhesive layer 72 is a close contact portion of the sealing plate. For example, when sealing the organic EL element substrate and the sealing substrate with an adhesive, such as an end portion of the sealing plate, It shall be the close contact part.

  Finally, the organic EL element substrate 10 and the sealing substrate 70 are bonded together. The pasting is preferably performed for 10 minutes or less after the surface substrate cleaning of the organic EL element substrate on which the dry sheet 61 is pasted. More preferably, 5 minutes or less is desirable.

First, an indium / tin alloy oxide was sputtered on a substrate 11 made of glass to form an ITO film having a thickness of 150 nm, and a first electrode was formed by patterning. Thereafter, UV / ozone treatment was performed so that the contact angle of the substrate 11 was 5 ° or less.
Next, a photosensitive resin solution made of polyimide resin is applied onto the substrate 11 on which the first electrode 21 is formed by a spin coater to form a photosensitive layer, and a series of patterning processes such as pattern exposure and development are performed. Thus, a partition wall 51 having a thickness of 1 μm was formed.

  Next, a 40 nm hole transport layer made of a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid on the first electrode 21, and poly [2-methoxy-5- (2′-ethyl). A functional layer 31 having a thickness of 120 nm having a two-layer structure including a light-emitting layer having a thickness of 80 nm made of (hexyloxy) -1,4-phenylenevinylene] (MEHPPV) was formed.

Next, 10 nm of calcium and 150 nm of aluminum are sequentially patterned and deposited on the functional layer 31 to form the second electrode 41, and a dry sheet 61 of DESICCANT-A (manufactured by Japan Gore-Tex Co., Ltd.) so as to cover the entire light emitting region. The organic EL element base material 10 was produced by pasting (see FIG. 1B).

  Next, the organic EL element substrate 10 was again subjected to UV / ozone treatment so that the contact angle was 5 ° or less.

  Next, an ultraviolet curable epoxy adhesive 72 was applied to the edge of the glass sealing cap 71 using a dispenser robot (see FIG. 1C).

  Next, the organic EL element substrate and the sealing base material 70 on which the adhesive layer was formed were bonded together and bonded and sealed with UV curing and thermal curing to obtain an organic electroluminescence element 100 (see FIG. 1A). .

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows one Example of the organic EL element which concerns on this invention, (a) is a schematic diagram which shows one Example of an organic EL element in a partial cross section, (b) is a cross section of one Example of an organic EL element board | substrate. The schematic diagram and partial enlarged view shown by (c) are the schematic diagrams which show one Example of a sealing base material in a cross section.

Explanation of symbols

10 ... Organic EL element base material 11 ... Substrate 21 ... First electrode 31 ... Functional layer 41 ... Second electrode 51 ... Partition wall 61 ... Dry sheet 70 ... Sealing base material 71 ... Sealing Plate 72 ... Adhesive 100 ... Organic electroluminescence element

Claims (3)

  An organic electroluminescence element substrate in which a plurality of light-emitting regions each including a functional layer including a first electrode and a light-emitting layer and a second electrode on a substrate; and a plurality of partition walls; and a sealing substrate in which an adhesive layer is formed; Is a method for producing an organic electroluminescent element, wherein at least UV ozone treatment is performed on the organic electroluminescent element substrate before the step of laminating the organic electroluminescent element substrate and the sealing substrate. A method for producing an organic electroluminescence element, comprising performing a surface cleaning treatment comprising plasma treatment.   The method for producing an organic electroluminescent element according to claim 1, wherein the light emitting region of the organic electroluminescent element substrate is entirely covered with a dry sheet.   An organic electroluminescent device manufactured using the method for manufacturing an organic electroluminescent device according to claim 1.