JP2004281529A - Organic active element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic active element and a display device which have barrier properties well balanced with prevention of their deteriorations in characteristics. <P>SOLUTION: An organic TFT 12 and a drive electrode 16 formed on a substrate 10 are covered with a passivation film 14. The passivation film 14 is a laminated film composed of a first film 28 and a second film 30. The first film 28 is formed of a certain material through a certain method so as not to damage the organic TFT under it. The second film 30 is made of ultraviolet-curing resin material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic active element and a display device.
[0002]
[Prior art]
There are various active elements such as diodes and transistors. Of these, those used for active matrix driving include TFTs having three terminals and MIMs having two terminals.
[0003]
For example, in the case of TFT, it can be roughly divided into an inorganic TFT using an inorganic material as a semiconductor and an organic TFT using an organic material as a semiconductor.
[0004]
It is known that the latter organic TFT has a relatively simple manufacturing process and a low manufacturing cost compared to the former inorganic TFT. In addition, the organic TFT has a feature that the film forming temperature can be made lower than that of the inorganic TFT. Therefore, the organic TFT can be formed on a plastic substrate having a low glass transition temperature relatively easily. An element in which an organic TFT is formed on a plastic substrate is superior to an element using a general inorganic material substrate in that it is flexible and lightweight.
[0005]
The organic TFT having the above features is attracting attention for application to electronic devices, and in particular, application research to display devices such as electronic displays has been actively conducted.
[0006]
However, organic TFTs are inferior in chemical resistance as compared with inorganic TFTs, and are susceptible to the influence of the surrounding environment. For this reason, there are problems that element characteristics are likely to deteriorate.
[0007]
In particular, when considering application to a display device, it is necessary to form a display element such as a liquid crystal layer or a light emitting layer on the organic TFT using a display material such as a liquid crystal or a light emitting material. In the manufacturing stage of forming, and also in the stage of using the completed display device, the display material may contaminate the organic semiconductor and deteriorate the characteristics of the display element.
[0008]
In order to prevent such a problem, it is necessary to cover the organic TFT with an appropriate passivation film (protective film).
[0009]
Several examples of forming a passivation film in a display device using an organic TFT have been reported.
[0010]
For example, polyvinyl alcohol (hereinafter, also referred to as PVA), which is a polymer material, is used as a material for the passivation film, and this is dissolved in water as a solvent and applied to the organic TFT to give it to the organic TFT as a base. It has been reported that damage can be reduced (see Non-Patent Document 1, for example).
[0011]
In addition, it is reported that a passivation film with high barrier properties that prevents gas and moisture permeation can be obtained by sputtering silicon TFT (organic nitride) as the material of the passivation film and sputtering the organic TFT. (See, for example, Non-Patent Document 2).
[0012]
[Non-Patent Document 1]
C. D. Sheraw et al. “Organic thin film transistor-driven polymer-dispersed liquid crystal displays on flexible polymeric substrates” Appl. Physics. letters, Vol. 80, no. 6, pp 1088-1090 (2002)
[0013]
[Non-Patent Document 2]
P. Mach et al. "Monolithically integrated, flexible display of polymer-dispersed liquid crystal driven by rubber-stamped organic thin film transformers." Physics. letters, Vol. 78, no. 23, pp 1088-1090 (2002)
[0014]
[Problems to be solved by the invention]
However, among the examples in which the above-described passivation film is formed, those using the former polymer material do not have a high barrier property of the passivation film, and therefore completely prevent the display material such as liquid crystal from penetrating into the organic TFT. Therefore, for example, it is necessary to increase the thickness of the passivation film by multilayering it. However, in the case of a display device using a liquid crystal layer, for example, when the thickness of the passivation film is increased, the capacitance of the film is reduced, so that the voltage applied to the liquid crystal layer is reduced due to the voltage division ratio. For this reason, it is necessary to increase the drive voltage, and problems associated therewith arise.
[0015]
On the other hand, when using the latter inorganic material, when the passivation film is formed on the organic TFT by sputtering, the surface properties and film quality of the organic TFT depend on the energy when ions of the film formation material collide with the organic TFT. May be affected. Further, since a dense passivation film needs to be formed at a certain high temperature, it is not suitable for a process using a plastic substrate having poor heat resistance.
[0016]
The present invention has been made in view of the above problems, and has a balance between barrier properties and prevention of deterioration of device characteristics, which has an appropriate barrier property and causes little deterioration in device properties that may occur when forming a passivation film. It is an object of the present invention to provide a good organic active element and a display device including the organic active element.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, an organic active device according to the present invention is an organic active device manufactured on a substrate and covered with a passivation film, wherein the passivation film is applied under a condition not using an organic solvent and at a low temperature. A first organic film formed on the organic active element by a method or an immersion method, and a second organic film formed on the first organic film using an ultraviolet curable resin. It is characterized by that. Here, the organic solvent non-use condition means that a solvent such as water is used without using an organic solvent as a solvent when the material of the first organic film used by application or immersion is used in the form of a solution. Say. The low temperature means that the organic TFT is not damaged, and the low temperature means a temperature of about room temperature to 80 ° C., for example.
[0018]
The organic active element according to the present invention is an organic active element manufactured on a substrate and covered with a passivation film. The passivation film includes a first organic film having gas barrier properties and the first organic film. It is characterized by comprising a second organic film formed using an ultraviolet curable resin.
[0019]
As a result, an organic active element having an appropriate barrier property and having a good balance between barrier property and prevention of deterioration of element characteristics can be obtained in which the element characteristics that can occur when forming a passivation film are small.
[0020]
In this case, it is preferable that the material of the first organic film is polyvinyl alcohol, polyvinyl phenol, or an LB film.
[0021]
In this case, if the organic active element is an organic TFT, the above effect can be suitably obtained.
[0022]
In this case, if the substrate is a plastic film substrate, a flexible substrate having no damage can be suitably obtained.
[0023]
In addition, the display device according to the present invention can obtain the above-mentioned effect suitably when a display element is formed on the organic active element using a display material, and obtain a high-performance image display. Can do.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the organic active element and display device according to the present invention (hereinafter referred to as this embodiment) will be described below with reference to the drawings, taking a liquid crystal display device using an organic TFT as an example. To do.
[0025]
First, an organic TFT (organic active element) according to this embodiment will be described with reference to FIG.
[0026]
In the organic TFT according to this embodiment, the organic TFT 12 formed on the substrate 10 is covered with a passivation film 14. In addition, the drive electrode 16 extending from the organic TFT 12 is also covered with the passivation film 14. However, the configuration is not limited thereto, and the drive electrode 16 may be exposed from the passivation film 14. The organic TFT 12 may be embedded in the substrate 10.
[0027]
As the substrate 10, a substrate formed of an appropriate material such as glass, quartz, or plastic can be used.
[0028]
The organic TFT 12 has a gate electrode 18, a gate insulating film 20, and an organic semiconductor 22 sequentially on the substrate 10, and further has a source electrode 24 and a drain electrode 26 facing and spaced apart from the organic semiconductor 22. It is a configuration.
[0029]
The gate electrode 18 is a material appropriately selected from, for example, tantalum, aluminum, titanium, niobium, zirconium, hafnium, chromium, molybdenum, molybdenum-tantalum alloy, or a conductive polymer such as polyethylenedioxythiophene (PEDT or PEDOT). It is formed to a thickness of about several hundred nm.
[0030]
The gate insulating film 20 is formed to a thickness of about several tens to 100 nm using, for example, an inorganic material such as BZT, Al ₂ O ₃ , Ta ₂ O ₅ , HfO, or ZrO, or an organic insulating material such as polyimide.
[0031]
The organic semiconductor 22 is formed on the gate insulating film 20 with a thickness of about 50 nm using, for example, an organic material such as pentacene as a material.
[0032]
The source electrode 24 and the drain electrode 26 are formed in a strip shape with a thickness of about 100 nm on the organic semiconductor 22 using, for example, Au as a material.
[0033]
The drive electrode 16 is provided in connection with the drain electrode 26 and is formed of a material such as Au or Al.
[0034]
The passivation film 14 is a laminated film including a first film 28 formed on the organic TFT 12 and a second film 30 formed on the first film 28. Each of the first film 28 and the second film 30 may be a single layer film or may be a laminated film composed of a plurality of layers.
[0035]
The first film 28 is formed by a material and a manufacturing method that do not cause damage to the organic TFT as a base. The first film 28 is formed of a material having an appropriate gas barrier property.
[0036]
That is, the first film 28 can be formed by dissolving, for example, in water to form a solution without using an organic solvent as a solvent, and by immersing this solution in a coating method or in a solution. Is formed using an organic material having an appropriate barrier property. For this reason, the first film 28 can be formed by a simple method without damaging the organic TFT 12.
[0037]
As such an organic material, for example, the above-described PVA can be preferably used in consideration of ensuring good wettability with an electrode material or the like. Moreover, polyvinylphenol can also be used instead of PVA. Furthermore, other organic materials having an appropriate gas barrier property can be used without limiting the production method to the coating method or the like. Further, in place of these coating films, an LB film (Langmuir Bladegett membrane film) can also be used.
[0038]
The first film 28 is formed to a thickness of about 50 to 100 nm, for example.
[0039]
The second film 30 is formed with a thickness of, for example, about 0.5 μm using an ultraviolet curable resin material.
[0040]
As the ultraviolet curable resin material, for example, an acrylic resin can be preferably used from the viewpoint of forming a film in a short time, and an epoxy resin can be preferably used from the viewpoint of film quality stability.
[0041]
The second film 30 is more dense than an ordinary organic film and has an appropriate barrier property. Further, the second film 30 is excellent in chemical resistance including an organic solvent.
[0042]
In addition, since the second film 30 does not require a high-temperature process, the second film 30 and the first film 28 do not damage the organic TFT 12 or a substrate using a plastic film material having poor heat resistance due to heat.
[0043]
About the manufacturing method of the organic TFT according to the present embodiment configured as described above, the organic TFT itself can be manufactured by a usual method (ordinary method), and thus the description is omitted, and the passivation film is formed on the organic TFT 12. A method of manufacturing 14 will be described below with reference to FIGS. 2 (a) and 2 (b).
[0044]
First, a method for producing the first film 28 using PVA as a material will be described.
[0045]
For example, a 10% by mass solution is prepared by dissolving PVA in water. This solution is applied over the entire surface of the substrate 10 on which the organic TFT 12 and the drive electrode 16 are formed using an appropriate application method such as a spin coating method or an ink jet method. Thereafter, drying is performed at a temperature of about 70 to 80 ° C. to remove moisture, and a first film 28 made of PVD is obtained.
[0046]
Accordingly, the first film 28 can be formed by a simple manufacturing method. At this time, since the film is manufactured under an organic solvent, that is, without using an organic solvent as a solvent, an organic solvent is used. When used, there is no deterioration of the characteristics of the organic TFT 12 that may occur when the organic solvent penetrates into the organic TFT 12.
[0047]
In addition, since the film is produced at a low temperature such as room temperature, the characteristics of the organic TFT that may occur when the film is produced at a high temperature are not deteriorated. Moreover, a flexible element can be obtained using a plastic film substrate with low heat resistance as the substrate.
[0048]
Note that the first film 28 may be an LB film formed by immersing the organic TFT 12 in water in which an organic compound having both a hydrophilic group and a hydrophobic group is dissolved.
[0049]
Next, a method for producing the second layer 30 using an ultraviolet curable acrylic resin will be described.
[0050]
An ultraviolet curable acrylic resin is applied over the entire surface of the first film 28 by a coating method such as a spin coating method as in the case of the first film 28. Next, the resin is cured by irradiating with ultraviolet rays to obtain a second film 30 made of an ultraviolet curable acrylic resin.
[0051]
Thus, the second film 30 can be formed by a simple manufacturing method, and at this time, since a high temperature process is not required to form the film, the deterioration of the characteristics of the organic TFT due to heat, etc. There is no invitation.
[0052]
When the drive electrode 16 is exposed from the passivation film 14, the passivation film 14 is formed in a predetermined pattern using a method such as mask vapor deposition or lithography as usual.
[0053]
The organic TFT according to this embodiment described above has an appropriate barrier property, and a passivation film formed without damaging the organic TFT can be obtained by a simple method. In other words, the organic TFT according to this embodiment has an excellent balance between barrier properties and prevention of deterioration of the organic TFT.
[0054]
The first film 28 is located between the organic TFT 12 and the second film 30 and also functions as an interlayer film. That is, the first film 28 functions as a buffer material until the second film 30 is obtained by curing the ultraviolet curable resin applied on the first film 28, or the organic TFT 12. It functions as a smoothing layer that smoothes irregularities that may occur on the surface.
[0055]
Next, a liquid crystal display device (display device) according to the present embodiment will be described with reference to FIG.
[0056]
In FIG. 1, the liquid crystal display device according to the present embodiment uses liquid crystal as a display material on the passivation film 14 of the organic TFT 12 covered with the passivation film 14 according to the present embodiment. A liquid crystal layer 32 is provided, and a counter electrode 34 is provided on the liquid crystal layer 32 to form a display element.
[0057]
The liquid crystal layer 32 is formed by injecting liquid crystal between the counter electrode 34 and the passivation film 14. For the liquid crystal, a normal appropriate material can be used, and it can be manufactured by an appropriate method.
[0058]
The counter electrode 34 can be manufactured by a normal method using a normal material.
[0059]
The liquid crystal display device according to the present embodiment can suitably exhibit the effects of the organic TFT according to the present embodiment, and the liquid crystal penetrates and forms the organic TFT when the liquid crystal layer is formed. The damage you get is prevented. The liquid crystal display device according to this embodiment can obtain a high-performance image display.
[0060]
In this case, the passivation film 14 made of an organic material is also formed on the drive electrode 16. However, since the thickness of the passivation film 14 is significantly smaller than the thickness of the liquid crystal layer 32, there is a problem in driving. There is nothing.
[0061]
The result of measuring the static characteristics of the organic TFT of the liquid crystal display device according to this embodiment is shown in FIG. As a reference example, FIG. 4 shows the result of measuring the static characteristics of the organic TFT when liquid crystal is directly injected onto the PVA film of a liquid crystal display device in which only the PVA film is provided as a passivation film on the organic TFT. .
[0062]
3 and 4, it is clear that the organic TFT of FIG. 4 has a significantly reduced drain current value and poor gate controllability, but the organic TFT according to this embodiment of FIG. No deterioration of characteristics as shown in FIG. 4 is observed.
[0063]
【The invention's effect】
According to the organic active device of the present invention, in the organic active device manufactured on the substrate and covered with the passivation film, the passivation film is organically active by a coating method or a dipping method under a condition not using an organic solvent and at a low temperature. A first organic film formed on the element and a second organic film formed on the first organic film using an ultraviolet curable resin, or formed on a substrate and passivated. In an organic active element covered with a film, a passivation film is composed of a first organic film having gas barrier properties and a second organic film formed on the first organic film using an ultraviolet curable resin. Thus, an organic active element having a good balance between barrier properties and prevention of deterioration of element characteristics can be obtained.
[0064]
Moreover, according to the organic active element which concerns on this invention, since a board | substrate is a plastic film board | substrate, a flexible board | substrate without damage can be obtained suitably.
[0065]
Further, according to the display device according to the present invention, the effect of the organic active element can be suitably obtained, and a high-performance image display can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a liquid crystal display device using an organic TFT according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a method of manufacturing an organic TFT according to the present embodiment, and FIG. 2 (a) is a diagram illustrating a process of forming a first film, and FIG. 2 (b) FIG. 4 is a diagram illustrating a process of forming a first film.
FIG. 3 is a diagram illustrating drive characteristics of the liquid crystal display device according to the present embodiment.
FIG. 4 is a diagram showing drive characteristics of a liquid crystal display device of a reference example.
[Explanation of symbols]
10 Substrate 12 Organic TFT
14 Passivation film 16 Drive electrode 18 Gate electrode 20 Gate insulating film 22 Organic semiconductor 24 Source electrode 26 Drain electrode 28 First film 30 Second film 32 Liquid crystal layer 34 Counter electrode

Claims (7)

In an organic active element manufactured on a substrate and covered with a passivation film,
The passivation film includes a first organic film formed on the organic active element by a coating method or a dipping method under an organic solvent-free condition and at a low temperature, and an ultraviolet curable resin is formed on the first organic film. An organic active element comprising a second organic film formed by using the organic active element. In an organic active element manufactured on a substrate and covered with a passivation film,
The passivation film is composed of a first organic film having gas barrier properties and a second organic film formed on the first organic film using an ultraviolet curable resin. Organic active element. 3. The organic active element according to claim 1, wherein the material of the first organic film is polyvinyl alcohol or polyvinyl phenol. 3. The organic active element according to claim 1, wherein the first organic film is an LB film. It is an organic TFT, The organic active element of any one of Claims 1-4 characterized by the above-mentioned. The organic active element according to claim 1, wherein the substrate is a plastic film substrate. A display device, wherein a display element is formed using a display material on the organic active element according to claim 1.

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