JP2007214079A - Capture agent for top emission type organic el device, and top emission type organic el device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capture agent for a top emission type organic EL device, easy to handle and superior in optical characteristics, and having high capture capacity of water and oxygen. <P>SOLUTION: The capture agent for the top emission type organic EL device is composed of a compound expressed by the following formula. R<SP>1</SP>R<SP>2</SP>R<SP>3</SP>M, provided that R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>are respectively one kind selected from a group made of hydrogen atom, alkyl group, alkenyl group, alkynyl group, cyclic alkyl group, aryl group, alkoxy group, carboxyl group, thiolate group, and second class amino group and may be mutually same or different, but, is selected to have one or more M-C bond as a trapping agent. In this case, M is aluminum or boron. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic EL (Eletroluminescence) device, in particular, a light extraction portion of a top emission type EL device that performs light extraction from the opposite side of a driving circuit board such as a thin film transistor (TFT). The present invention relates to a water and oxygen scavenger that can be used, and a top emission type device.

An organic EL device injects electrons and holes into an organic material, electrically generates an excited state of the organic material called a light-emitting material, and takes out the energy emitted when the excited species is relaxed to the ground state as light. This is a next-generation display device that performs display.
Two structures have been proposed for the structure of organic EL devices. That is, a bottom emission structure that extracts light from the transparent electrode substrate side where the drive circuit is disposed, and a transparent electrode disposed on the opposite side of the drive circuit substrate, and light is extracted from a wide opening without being blocked by the drive circuit. Top emission structure. In addition to a large opening, the top emission structure makes it easy to incorporate a thin film transistor that directly drives each pixel into a driver circuit.

The operation mechanism of an organic EL device is based on causing an organic material to repeatedly perform a redox reaction. For this reason, if a thermodynamically stable organic material is selected and used, its kinetics is highly reactive with oxygen and / or water, and the performance deteriorates due to the influence of trace amounts of water and oxygen.
Therefore, a sealed container is usually used to arrange the organic EL device, and it is necessary to keep oxygen and / or moisture below a trace amount as much as possible. Therefore, the production of the organic EL device is performed in an ultrahigh vacuum and / or in an inert atmosphere.

In addition, as an organic EL device configuration, consideration is given to reducing these effects as much as possible by placing a capture agent in the device that captures outgas derived from materials and / or degradation factors that enter from the sealed portion of the sealed container. is doing.
However, the trapping agent capable of removing both oxygen and water of the top emission type organic EL device has been limited in its capability.

  Patent Document 1 discloses an invention using alkali (earth) metal having very high reactivity with water and oxygen as a scavenger, but its handling is extremely dangerous and complicated. The method was also limited when it was placed inside. Furthermore, when a device provided with these is destroyed by disposal or accident and exposed to high-concentration water and / or oxygen in a normal atmospheric atmosphere, there is a possibility of spontaneous ignition.

  In the method described in Patent Document 2, the capturing ability can be finely adjusted by using a plurality of materials. However, this method is not a simple method because the target capturing agent molded body is made by a plurality of very complicated processing steps. Moreover, in order to distribute the molded body to the organic EL device, a process of arranging a molded body in the device other than the process of manufacturing the device is required. Furthermore, the top emission type device has a problem that a place where the molded body is disposed cannot be sufficiently formed in the device.

  Patent Document 3 is characterized in that a material constituting the organic EL layer is used as a capturing agent. However, the reaction rate with water and / or oxygen is remarkably faster in an organic material that is transferring electrons or holes, that is, in an excited state. For this reason, it is doubtful whether the organic material proposed as a scavenger inherently retains its function high, and in terms of transparency, when organic materials containing hetero elements (oxygen, nitrogen, sulfur, etc.) deteriorate Coloring is generally known and can be problematic even if the scavenger layer is thin.

Thus, there are not many conventional scavengers capable of scavenging both oxygen and hydrogen, and if any, they are dangerous to handle. Moreover, in order to use for a top emission type organic EL device, it is necessary to satisfy the requirement of translucency.
JP 2002-008852 A JP 2005-270959 A JP 2006-004721 A

An object of the present invention is to provide a scavenger for a top emission type organic EL device that is easy to handle, has excellent optical characteristics, and has a high ability to trap water and oxygen.
An object of the present invention is to provide a top-emission organic EL device that can display with high quality, has little influence of water and oxygen, and has a long lifetime.

According to the present invention, there is provided a top emission type organic EL device scavenger comprising a compound represented by the following chemical formula.
R ¹ R ² R ³ M
(R ¹ , R ² and R ³ are each selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cyclic alkyl group, an aryl group, an alkoxy group, a carboxyl group, a thiolate group, and a secondary amino group. One selected, which may be the same or different from each other, but selected to have one or more MC bonds, where M is aluminum or boron.)

Here, the compound and the binder may be dissolved in a solvent.
In addition, according to the present invention, there is provided a top emission type organic EL device characterized in that the scavenger is arranged in a light extraction portion of the top emission type organic EL device.

The scavenger of the present invention is easy to handle, has extremely excellent water and oxygen scavenging capabilities, exhibits a sufficient function even at extremely low concentrations, and has excellent translucency, etc. It is suitable for a top emission type organic EL device that can be taken, and the light emission lifetime can be greatly improved. Moreover, since the capture | acquisition agent of this invention can make a capture | acquisition agent solution a uniform solution, it becomes possible to distribute | arrange to the various positions of a top emission type organic EL device by the apply | coating method.
In addition, according to the top emission type organic EL device of the present invention, it is possible to suppress a decrease in life due to water or oxygen, and therefore, it is possible to achieve a long life.

Hereinafter, a water and oxygen scavenger for a top emission type organic EL device and a top emission type organic EL device according to embodiments of the present invention will be described.
The feature of the water and oxygen scavenger according to the embodiment of the present invention is that the compound represented by the following formula (1) alone is bifunctional so that water and oxygen can be thinned. It is superior to various scavengers that have been studied in EL panels.

R ¹ R ² R ³ M (1)
In formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom, alkyl group, alkenyl group, alkynyl group, cyclic alkyl group, aryl group, alkoxy group, carboxyl group, thiolate group and 2 One kind selected from the group consisting of secondary amino groups, which may be the same as or different from each other, but has one or more CM bonds. Here, M is aluminum or boron. The groups R ¹ , R ² and R ³ preferably have 1 to 20 carbon atoms, more preferably 2 to 18 carbon atoms, and may be the same or different. These compounds play a useful role as capturing agents for organic EL devices by reacting moisture, oxygen, and the like with the CM bond.

The reaction with water is given by:
_{C-M + H 2 O →} C-H + M (OH)
The reaction with oxygen is given by:
2C-M + O ₂ → 2C-OM

Specific examples of R ¹ , R ² and R ^{3 in} the formula (1) include hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group. Group, undecyl group, dodecyl group, hexadecyl group, octadecyl group, alkenyl group having 1-18 carbon atoms, propenyl group, butenyl group, octenyl group, dodecenyl group, octadecenyl group, propynyl group Alkynyl group such as phenylethynyl group, alicyclic alkyl group such as cyclopropyl group and cyclohexyl group, aryl group such as phenyl group and benzyl group, alkoxy group such as ethoxy group, propoxy group and butoxy group, etc. Can be mentioned. These alkyl group, alkenyl group, alkynyl group and alkoxy group may be linear, cyclic or branched.

  Specific examples of the compound represented by the formula (1) include triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tricyclopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-t-butyl. Aluminum, tri-2-methylbutylaluminum, tri-n-hexylaluminum, tricyclohexylaluminum, tri (2-ethylhexyl) aluminum, tri-n-octylaluminum, tri-n-decylaluminum, triphenylaluminum, tribenzylaluminum , Dimethylphenylaluminum, dibutylphenylaluminum, diisobutylphenylaluminum, methyldiphenylaluminum, ethoxydiethylaluminum, ethoxy Can be mentioned di -n- octyl aluminum, triethyl borane, tributyl borane, tri -n- octyl borane, tri -n- dodecyl borane, and the like triphenyl borane. These compounds can be used alone or in admixture of two or more kinds.

Considering the vapor pressure of the product generated by the reaction with moisture, oxygen, etc., preferably a group having 8 or more carbon atoms, preferably tri-n-octylaluminum, tri-n-decylaluminum, tri-n-dodecylaluminum, etc. In view of the transparency of the scavenger composition, tri-n-octylaluminum and tri-n-decylaluminum are more preferable.
The type of binder of the scavenger used in the embodiment of the present invention may be an inorganic material or an organic material.

  Examples of the inorganic binder include alkoxysilane polymers. Alkoxysilanes include tetramethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, dimethoxydimethylsilane, dimethoxydiethylsilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, diethoxydimethylsilane, diethoxydiethylsilane And dimethoxymethylphenylsilane. A small amount of alkoxyzirconium can also be added to improve the coating strength.

  In the alkoxysilane polymer, 0.1 mol% or more of water is added to the alkoxysilane, and a very small amount of acid or alkali is added as a catalyst to cause the reaction. It is also possible to cause the polymerization reaction by heating without adding a catalyst. The polymer can be obtained by concentrating and drying the reaction solution at a high temperature, but it is preferable to redissolve it in a solvent and store it.

  As the organic binder, a transparent resin that does not react with the scavenger can be used. For example, acrylic resin and styrene resin. Liquid polymers and petroleum resins can be used as the organic binder. Examples of the liquid polymer include liquid polybutene and liquid polybutadiene. Examples of petroleum resins include Nisseki Neopolymer. Furthermore, various rubbers can be used as the organic binder. For example, styrene-butadiene rubber, polyisoprene, polybutadiene, butyl rubber, and the like can be used.

  Further, an organic binder and an inorganic binder may be mixed, or a hybrid type resin reacted in advance may be used. Examples of the hybrid type resin include acrylic silicones such as Kanekazemulac. A solution for forming a coating film can be prepared by dissolving these transparent resins in an organic solvent. The concentration of the resin solution is 10 wt% or more, preferably 20 to 80 wt%.

  For preparing the scavenger coating film, a scavenger containing the compound of the present invention is added to the binder solution at 10 wt% or more, preferably 20 to 80 wt% with respect to the solid content of the binder, and sufficiently stirred to obtain a uniform solution. Under an inert atmosphere, this scavenger solution is applied to a sealing substrate of a top emission type organic EL device, such as a cap glass substrate, or a desired position of the device, and then a volatile component is distilled off. The coating method may be a spin coater, roll coater, spray coater, droplet discharge method, dispenser or the like, and is not particularly limited. The film forming temperature is 50 ° C. or higher, preferably 100 to 200 ° C., and it is not particularly limited as long as volatile components such as a solvent of the coating solution can be removed.

As a method for applying the composition, for example, a spin coating method, a roll coating method, a curtain coating method, a dip coating method, a spray method, a droplet discharge method, or the like can be used, and the method is not particularly limited. The inkjet method is preferable.
The film forming temperature is 50 ° C. or higher, preferably 100 to 150 ° C. The temperature is not particularly limited as long as the temperature can sufficiently remove the solvent of the coating solution.

  The water and oxygen scavenger for top emission type organic EL devices according to the embodiment of the present invention are easy to handle and have excellent water and oxygen scavenging capabilities. Further, it exhibits a sufficient function even at a very low concentration, and has excellent optical properties (visible light transmittance and refractive index). Representative optical characteristics of the trapping material are as follows. The transmittance of light in the visible light region (400 to 800 nm) is 95% or more, and the refractive index (wavelength: 589.3 nm (sodium D line) is used. At 1.2 ° C.). Thus, since the optical characteristics are excellent, it is suitable for a top emission type organic EL device having a wide opening, and the light emission life of the organic EL device can be greatly improved.

Moreover, since the capturing agent according to the embodiment of the present invention can make the capturing agent solution a uniform solution, it can be arranged at various positions of the top emission type organic EL device by a coating method.
In addition, according to the top emission type organic EL device of the present invention (the organic EL device whose light extraction is performed from the light extraction portion on the opposite side of the driving circuit substrate such as a thin film transistor), the light transmittance in the visible light region, etc. Even if an organometallic compound having excellent optical characteristics is disposed in the light extraction portion, it functions as a water and oxygen scavenger without deteriorating the device characteristic quality, so that high-quality display can be performed. It is possible to extend the service life.

[Example 1]
A scavenger solution was prepared by uniformly dissolving 100 grams of trioctylaluminum in 100 grams of a 50 wt% toluene solution of sufficiently dried liquid paraffin. The scavenger solution was applied on a 500 μm thick glass substrate by the inkjet method for each RGB pixel area unit, and then heated at 140 ° C. for 20 minutes. Next, from the substrate side having the thin film transistor element, Al / Ca as a cathode, each RGB type light emitting pixel as a light emitting layer, and a conductive polymer (PEDOT-PSS manufactured by Bayer) as a hole injection layer, A glass substrate with ITO (500 μm thick) was laminated as an anode, and a glass with a trapping agent was bonded to the whole panel for sealing. The obtained top emission type organic EL panel showed excellent light emission luminance, no dark spots (non-light emitting points) were generated, and the light emission life was also good.

The dehydration performance of trioctyl aluminum is shown in FIG. FIG. 1 shows a measurement of time-dependent changes in humidity in a container using a humidity sensor placed in a sealed container with a volume of 640 cm ³ on which 1.5 grams of dried and solidified trioctyl aluminum is placed on an aluminum dish. Results are shown. As a comparison object, comparison was made with calcium oxide and Hope Pharmaceutical's Olipe AOO (main component: aluminum oxide octylate). Trioctylaluminum (Graph A in FIG. 1) showed excellent moisture absorption capacity for the two scavengers for comparison.
Moreover, the deoxygenation performance of trioctylaluminum is shown in FIG. The measurement was performed in the same manner as in the case of the dehydration performance in FIG. In addition, 2.0 grams of trioctylaluminum was used, and the change over time in the oxygen concentration in the container was measured with an oxygen sensor. As shown in FIG. 2, trioctylaluminum (graph A in FIG. 2) showed excellent deoxygenation ability.

[Example 2]
100 g of tri-n-dodecylaluminum was added to 100 g of a 50 wt% diglyme solution obtained by polymerizing dicyclopentanyl methacrylate (FA-513M manufactured by Hitachi Chemical Co., Ltd.) with AIBN (azobisisobutyronitrile) and uniformly mixed and dissolved. . The top emission type organic EL panel substrate produced in the same manner as in Example 1 using the composition as a scavenger showed good emission luminance, no dark spots were generated, and the emission lifetime was also good.

[Comparative Example 1]
The same scavenger composition as in Example 1 was applied to the space between the wirings in the vicinity of the pixel portion on the thin film transistor element substrate side by an ink jet method, and heated to form a film at 140 ° C. for 20 minutes. Polymer type RGB light emitting pixels were arranged, and a 500 μm thick glass plate was laminated and sealed. The obtained top emission type organic EL panel showed good light emission luminance in the initial stage, but because the absolute amount was small because the capturing agent was arranged between the wirings, dark spots appeared from the initial stage, and the light emission life was also as in Example 1. It was short compared to.

  In the top emission type organic EL device, water and oxygen scavengers can be arranged at various positions such as a light extraction portion.

It is a figure which shows the water-capturing performance characteristic of the trapping agent for top emission type organic EL devices which concerns on the Example of this invention. It is a figure which shows the deoxygenation characteristic of the scavenger for top emission type organic EL devices which concerns on the Example of this invention.

Claims (3)

A scavenger for a top emission type organic EL device, comprising a compound represented by the following chemical formula.
R ¹ R ² R ³ M
(R ¹ , R ² and R ³ are each selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a cyclic alkyl group, an aryl group, an alkoxy group, a carboxyl group, a thiolate group, and a secondary amino group. One selected, which may be the same or different from each other, but selected to have one or more MC bonds, where M is aluminum or boron.)   A capturing material for a top emission type organic EL device, comprising the compound according to claim 1 and a binder dissolved in a solvent.   A top emission type organic EL device comprising the scavenger according to claim 1 or 2 arranged in a light extraction portion of the top emission type organic EL device.

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