JP2007294413A - Organic el panel and manufacturing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL panel with high productivity by reducing dehydration treatment time of a first protective film (flattened film) without increasing processes up to formation of a second protective film (separating film). <P>SOLUTION: The second protective film 206 includes an area for exposing the first protective film 203 between adjacent first electrodes 205. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic EL panel, and in particular, provides an organic EL panel in which a substrate dehydration time is kept low and a method for manufacturing the same.

  The structure of the organic EL device, which is currently under development, is basically a laminate of anode / at least an organic layer having a light emitting layer / cathode. A transparent anode is formed on a substrate using a glass plate or the like to emit light. Is known to be taken out from the substrate side. Recently, a panel of an active matrix system in which a driving transistor is provided for each light emitting pixel has been studied.

  Furthermore, the demand for high-definition and low power consumption is increasing for organic EL panels, and there is an increasing expectation for realizing a high-quality active matrix organic EL panel at a low cost.

  FIG. 1 is a schematic diagram of a general structure of an active matrix organic EL panel. As shown in FIG. 1, the active matrix organic EL panel includes a plurality of transistors 12 on a substrate 11. A planarizing film 13 is provided on the plurality of transistors 12, and further, a plurality of anodes 15 connected through contact holes 14 and a separation film 16 that covers the end surfaces while leaving openings of the plurality of anodes are provided. . Further, it is composed of an organic layer having at least a light emitting layer 17 thereon and a cathode 18. The plurality of anodes are supplied with currents controlled by driving circuits of a plurality of transistors, respectively, so that electroluminescence is obtained through the light emitting layer and the cathode.

  The reason why the planarizing film 13 is provided is to cover the unevenness of 0.1 to 1 μm of the plurality of transistors 12 and to maintain the smoothness of the substrate surface.

  The planarizing film 13 is formed by spin coating with an organic resin material such as acrylic resin.

  The separation film 16 is provided because an organic resin material such as polyimide resin is formed by spin coating to protect the end face of the patterned anode 15.

  Further, the separation film 16 is formed by depositing an electrically insulating inorganic material such as silicon nitride, silicon oxide, SiON, or aluminum oxide by magnetron sputtering, high-frequency ion plating, chemical vapor deposition (CVD), or the like. It has been.

  On the other hand, it is known that organic EL elements are not resistant to moisture. In other words, organic materials used in organic EL are easily decomposed and altered with respect to moisture and solvents, and problems such as a decrease in luminance near dark spots and pixel edges, and a decrease in luminance during high-temperature storage occur.

  On the other hand, when the planarizing film 13 is made of an organic resin, each film is in a state containing a large amount of moisture after the film formation / patterning process by the spin coating method. Furthermore, the planarization film 13 also contains a large amount of moisture by patterning the anode 15 that is a pixel electrode on the planarization film.

When the light emitting layer is formed in this state, the light emitting layer absorbs moisture, resulting in dark spots and a decrease in luminance. Therefore, it was necessary to perform dehydration by baking at a high temperature before forming the light emitting layer (Patent Document 1).
JP 2003-332058 A

  However, sufficient dehydration processing time is required to prevent a decrease in luminance of the organic EL element, and the processing time for that time is long and there is a problem in productivity.

  This is because a metal electrode, which is an anode, is formed on the planarizing film, and the moisture dehydration route is limited.

  When the separation membrane is made of an organic substance, the dehydration path of moisture contained in the planarization membrane enters the separation membrane from a slight surface in contact with the separation membrane, and permeates through the separation membrane to be discharged. It takes a long time.

  In addition, when the separation film is made of an electrically insulating inorganic material such as silicon nitride, silicon oxide, SiON, aluminum oxide, etc., the moisture is more difficult to permeate through the separation film as compared with the separation film made of an organic material. Dehydration of the chemical film becomes more difficult. Furthermore, the separation membrane may be cracked due to expansion of the water whose dehydration path is closed.

  The present invention has been made in view of the above points, and provides an organic EL panel with high productivity by reducing the dehydration time of the flattening film without increasing the number of steps until forming the separation film, and a method for manufacturing the same. The purpose is to do. And it aims at providing the organic electroluminescent panel with little deterioration by a water | moisture content.

The present invention includes at least a plurality of transistors on a substrate, a first protective film formed on the plurality of transistors, and electrically formed via the plurality of transistors and contact holes. A plurality of first electrodes to be connected; a second protective film covering end faces of the plurality of first electrodes; an organic layer stacked on the first electrode; and In an organic EL panel having a second electrode laminated thereon,
In the organic EL panel, the second protective film is provided with a region where the first protective film is exposed between the first electrodes adjacent to each other.

The present invention also includes a step of forming a plurality of transistors on a substrate, a step of forming a first protective film formed on the plurality of transistors, and the plurality of transistors via contact holes. Forming a plurality of electrically connected first electrodes, forming a second protective film so as to cover an end surface of the plurality of first electrodes, and In a method for manufacturing an organic EL panel, comprising: a step of forming an organic layer on a first electrode; and a step of forming a second electrode on the organic layer.
The step of forming the second protective film includes a step of providing a region in which the first protective film is exposed between the adjacent first electrodes. A method for manufacturing an organic EL panel is provided. .

  According to the present invention, the first electrode and the separation film as the second protective film are patterned so that the planarization film as the first protective film is exposed.

  Therefore, it is possible to efficiently dehydrate a planarized film made of a material having a high water absorption rate, such as an acrylic resin, without blocking the dehydration path by the first electrode or the separation film.

  With such a configuration, the dehydration time can be reduced without reducing productivity. And an organic EL panel with little deterioration by moisture can be provided.

  The organic EL panel according to the present invention is formed on a substrate at least by a plurality of transistors, a plurality of transistors, a first protective film made of an organic substance, a plurality of transistors, and contact holes. A plurality of first electrodes that are electrically connected, a second protective film that covers end faces of the plurality of first electrodes, an organic layer that is stacked on the first electrode, and an organic layer And a second electrode laminated on the substrate. The second protective film is provided with a region where the first protective film is exposed between the first electrodes adjacent to each other.

  As a result, when the moisture contained in the first protective layer, which is an organic substance, is dehydrated before forming the organic layer, the moisture contained in the first protective layer is converted into the first electrode or the second protective layer. It is dehydrated directly to the outside without being blocked. Therefore, more water can be dehydrated, resulting in an organic EL panel that is less susceptible to deterioration due to water.

  Further, the organic EL panel manufacturing method according to the present invention includes a step of forming a plurality of transistors on a substrate, a step of forming a first protective film formed on the plurality of transistors, and a plurality of transistors. Forming a plurality of first electrodes electrically connected to each other through a contact hole, and forming a second protective film so as to cover the end surfaces of the plurality of first electrodes arranged And a step of forming an organic layer on the first electrode, and a step of forming the second electrode on the organic layer. The step of forming the second protective film includes a step of providing a region where the first protective film is exposed between the adjacent first electrodes.

  As a result, when the moisture contained in the first protective layer is dehydrated before the organic layer is formed, the moisture contained in the first protective layer is blocked by the first electrode or the second protective layer. It can be dehydrated directly to the outside. Therefore, more water can be dehydrated in a short time, and the productivity of the organic EL panel can be increased. In addition, the method for manufacturing an organic EL panel according to the present invention includes a step of closing an exposed region of the first protective layer provided in the second protective layer after dehydrating moisture contained in the first protective layer. It may be. Furthermore, you may have the process of forming the organic layer which has a light emitting layer after the said process.

  Examples of the organic EL panel according to the present invention will be described below.

Example 1
FIG. 2 is a schematic view showing a part of a cross section of the organic EL panel used in the example of the present invention. 201 is a glass substrate, 202 is a transistor, 203 is a first protective film (planarization film), 204 is a contact hole region, 205 is a first electrode, 206 is a second protective film (separation film), and 207 is organic The layer, 208 is a second electrode, and 210 is a glass sealing cap.

  3 is a schematic plan view of the substrate of Example 1. FIG. 3A is a schematic pattern diagram of the first protective film, FIG. 3B is a schematic pattern diagram of the first electrode, and FIG. It is a patterning schematic diagram of the protective film. Reference numeral 301 denotes an exposed region, and 302 denotes a pixel opening.

  FIG. 4 is a schematic diagram showing a part of a cross section passing through the exposed region 301 of the panel of the first embodiment.

  The substrate used in Example 1 was a substrate having a pixel number of 160 × 120 dots and a pixel pitch of 0.25 × 0.25 mm.

  A plurality of transistors 202 for driving organic EL elements were formed on a glass substrate 201. In order to flatten the undulation of the transistor 202, an acrylic resin was coated as a first protective film 203 by spin coating. Next, as shown in FIG. 3A, the first protective film 203 was patterned. Directly thereon, Cr was deposited as a first electrode 205 by a DC magnetron sputtering method. Since acrylic resin is advantageous for maintaining flatness, it is preferably used for the first protective film. However, since the acrylic resin has a high water absorption rate, the coated first protective film contains a large amount of moisture.

  Next, the first electrode 205 was patterned as shown in FIG. Further thereon, a polyimide resin was coated as a second protective film 206 by spin coating. A polyimide resin is inferior in flatness compared to an acrylic resin, but has a water absorption rate of about 1/10, and thus is preferably used for a second protective film with little need to maintain flatness. Next, the second protective film 206 was patterned as shown in FIG. These films are patterned in each step by a normal photolithography method.

  Here, the first electrode 205 is provided with an exposed region 301 </ b> A for exposing the first protective film 203 next to the contact hole region 204 for obtaining electrical contact with the transistor 202. Similarly, the second protective film 206 is provided with an exposed region 301B in a region smaller than the exposed region 301A so as to correspond to the exposed region 301A. In this way, by using a region that does not contribute to the pixel opening 302 next to the contact hole region 204, the pixel aperture ratio can be maintained. In addition, since the acrylic resin of the first protective film 203 is exposed in the exposed region 301B, the moisture release rate is faster than the surface that is in contact with the polyimide resin having a low water absorption rate, which is the second protective film 206. Accordingly, it is possible to shorten the treatment time of the acrylic resin having a high water absorption rate in the dehydration treatment. Further, since the dehydration path of the first protective film 203 can be created without increasing the patterning process, the productivity is not lowered.

  After the above steps, dehydration treatment was performed in a vacuum high-temperature furnace. The dehydration conditions were 10 Pa under reduced pressure and a furnace temperature of 200 ° C. (high temperature) for a treatment time of 0.5 to 3 hours. Next, ultraviolet light was irradiated for about 10 minutes in a dry air atmosphere. In the case where the second protective film (separation film) is made of an organic material such as polyimide as described above, moisture contained in the second protective film is removed during the dehydration process of the first protective film (planarization film). Dehydration can be performed simultaneously.

  Next, an organic layer 207 including a hole injection layer, a light emitting layer, an electron transport layer, and an electron injection layer was formed by a resistance heating evaporation method in a vacuum film formation chamber. The total film thickness of these layers is 120 nm. Subsequently, a second electrode 208 was formed by a DC magnetron sputtering method. The material of the second electrode 208 is ITO, and the film thickness is 100 nm. Subsequently, a moisture-proof layer 209 was formed by a chemical vapor deposition (CVD) method. The moisture-proof layer is made of silicon nitride (SiNx) and has a thickness of 1 μm.

  Next, the substrate on which film formation has been completed is moved without being exposed to the atmosphere in a glove box that is substituted with dry nitrogen and maintained at a dew point of −70 ° C. or lower. Here, an ultraviolet curable resin is applied to the outer periphery of the panel display region, and a glass sealing cap 210 that has been previously washed to remove moisture is bonded. Then, the ultraviolet curable resin coated portion was irradiated with ultraviolet rays to be cured, and the sealed space was sealed with dry nitrogen to complete.

  With such a configuration, it is possible to produce a highly productive organic EL panel by reducing the dehydration time of the planarization film without increasing the number of steps until the separation film is formed.

(Comparative Example 1)
An organic EL panel of Comparative Example 1 was prepared by the same configuration and process as Example 1 except for the exposure mask in the patterning process of the first electrode 205 and the second protective film 206. 5A, 5B, and 5C illustrate patterning shapes including the first protective film 203, the first electrode 205, and the second protective film 206 of Comparative Example 1, respectively.

  FIG. 6 is a schematic view showing a part of the cross section of the panel of Comparative Example 1, and the cross section shown in FIG. 6 is a cross section corresponding to the cross section shown in FIG.

  When the organic EL panel prepared in Example 1 and Comparative Example 1 prepared as described above is driven and emitted in a high-temperature furnace under the conditions of atmospheric pressure and 80 ° C., the luminance deteriorates by 10% with respect to the initial area emission luminance. The elapsed time of was evaluated. The drive current density of various substrates was adjusted to 0.3 mA / mm 2. The result is shown in FIG.

  As shown in the result of FIG. 7, the dehydration time when the 10% luminance degradation curve of Comparative Example 1 is saturated requires 3 hours or more, whereas in Example 1, the dehydration time can be reduced in about 2 hours. is there.

(Example 2)
An organic EL panel of Example 2 was formed by the same configuration and process as Example 1 except for the exposure mask in the patterning process of the first protective film 203, the first electrode 205, and the second protective film 206. FIG. 8A, FIG. 8B, and FIG. 8C show patterning shapes including the first protective film 203, the first electrode 205, and the second protective film 206 of Example 2, respectively.

  As shown in FIG. 8, the exposed region 301B of the first protective film 203 is provided on the line so that the exposed range is larger than that of the first embodiment and the dehydration time is reduced. The results are also shown in FIG. 7 using the same evaluation method as in Example 1. However, compared with Example 1, the dehydration time when the 10% luminance degradation curve was saturated was reduced to 1.5 hours. However, since the organic EL panel of the present example has a lower pixel aperture ratio than that of Example 1, when driven under the same driving conditions as in Example 1, the light emission of the panel was slightly weakened.

  With such a form, a highly productive organic EL panel capable of reducing the dehydration time of the planarization film can be produced.

(Example 3)
As the second protective film 206, an electrically insulating inorganic substance is used.

  FIG. 9A, FIG. 9B, and FIG. 9C illustrate patterning shapes including the first protective film 203, the first electrode 205, and the second protective film 206 of Example 3, respectively.

  As shown in FIG. 9, the exposed region 301B of the first protective film 203 is provided between the pixels surrounding the pixels.

  Depending on the heating conditions of the dehydration process described later, the residual moisture in the planarization film may be vaporized and expanded during dehydration, causing the second protective film 206 to crack.

  Therefore, by providing an exposed region in parallel with each side of the rectangular first electrode 205, the residual moisture in the planarization film disposed under the first electrode 205 can be easily discharged. In addition, providing an exposed region on each side not only facilitates drainage of water by increasing the exposed area, but also has an effect of preventing stress from being concentrated on one side.

  As a result, cracking of the second protective film 206 can be suppressed.

  In this embodiment, the first electrode is rectangular, but may be any polygonal shape such as a square, parallelogram, trapezoid, triangle, hexagon, etc. The shape of the first electrode is limited to a rectangle. It is not a thing.

  The steps from formation of the transistor 202 over the glass substrate 201 to patterning of the first electrode 205 were performed in the same manner as in Example 2.

  Next, silicon nitride (SiNx) was formed as a second protective film 206 from above by a chemical vapor deposition (CVD) method.

  Note that silicon oxide, SiON, aluminum oxide, or the like can be used as the electrically insulating inorganic substance that can form the second protective film 206. As the film forming means for the second protective film 206, other vapor phase growth methods may be used as long as a dense film with few defects such as magnetron sputtering or high frequency ion plating can be obtained.

  Next, the protective film 206 was patterned as shown in FIG.

  Thereafter, the process from the dehydration process in the vacuum high-temperature furnace to the process of bonding the glass sealing cap 210 was performed in the same manner as in Example 2.

  Evaluation was performed in the same manner as in Examples 1 and 2. The results are shown in FIG. 7, and the dehydration time when the 10% luminance degradation curve is saturated as in Example 2 was 1.5 hours.

  With such a form, a highly productive organic EL panel capable of reducing the dehydration time of the planarization film can be produced.

It is a schematic diagram of an active matrix type organic EL panel. It is a schematic diagram showing a part of cross section of the organic EL panel of the present invention. 1 is a schematic plan view of an organic EL panel of Example 1. FIG. 3 is a schematic diagram illustrating a part of a cross section of an organic EL panel according to Example 1. FIG. 5 is a schematic plan view of an organic EL panel of Comparative Example 1. FIG. 6 is a schematic diagram showing a part of a cross section of an organic EL panel of Comparative Example 1. FIG. It is an evaluation result graph of the present invention. 6 is a schematic plan view of an organic EL panel of Example 2. FIG. 6 is a schematic plan view of an organic EL panel of Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Substrate 12 Transistor 13 Planarization film 14 Contact hole 15 Anode 16 Separation film 17 Organic layer 18 Cathode 201 Glass substrate 202 Transistor 203 First protective film (planarization film)
204 Contact hole region 205 First electrode 206 Second protective film (separation film)
207 Organic layer 208 Second electrode 209 Moisture-proof layer 210 Glass sealing cap 301 Exposed region 302 Pixel opening

Claims (9)

At least a plurality of transistors on the substrate, a plurality of first protective films formed on the plurality of transistors, and electrically connected to the plurality of transistors through contact holes. A first protective electrode, a second protective film covering end surfaces of the plurality of first electrodes, an organic layer stacked on the first electrode, and a stacked layer on the organic layer. An organic EL panel having a second electrode,
The organic EL panel, wherein the second protective film is provided with a region where the first protective film is exposed between the adjacent first electrodes.   2. The organic EL panel according to claim 1, wherein the first protective film is made of an acrylic resin, and the second protective film is made of a polyimide resin.   The organic EL panel according to claim 1, wherein the first protective film is made of an acrylic resin, and the second protective film is made of an electrically insulating inorganic substance.   4. The organic EL according to claim 3, wherein a region of the second protective film where the first protective film is exposed is provided in parallel with each side of the polygonal first electrode. panel. Forming a plurality of transistors on the substrate; forming a first protective film formed on the plurality of transistors; and electrically connecting the plurality of transistors through contact holes. A step of forming a plurality of first electrodes, a step of forming a second protective film so as to cover an end surface of the plurality of first electrodes, and a top of the first electrode. In the manufacturing method of the organic EL panel which has the process of forming an organic layer in a process, and the process of forming a 2nd electrode on the said organic layer,
The method of forming an organic EL panel, wherein the step of forming the second protective film includes a step of providing a region where the first protective film is exposed between the adjacent first electrodes.   6. The method of manufacturing an organic EL panel according to claim 5, wherein the first protective film is made of an acrylic resin, and the second protective film is made of a polyimide resin.   6. The method of manufacturing an organic EL panel according to claim 5, wherein the first protective film is made of an acrylic resin, and the second protective film is made of an electrically insulating inorganic substance.   8. The method of manufacturing an organic EL panel according to claim 5, further comprising a dehydration treatment step after the step of forming the second protective film. 9.   The method for producing an organic EL panel according to claim 5, wherein the dehydration process is a process of dehydration under reduced pressure and high temperature.

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