JP2006261058A - Organic el element, display device, and manufacturing method of organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element realizing the suppression of voltage drop and maintenance and improvement in image quality. <P>SOLUTION: Protection films 6, 7 are formed on a second electrode 5 which is an upper electrode, and a third electrode 8, that is, an auxiliary electrode which is electrically connected to the second electrode 5 is formed on the protection films. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL (Electro Luminescence) element, a display device using the organic EL element, and a method for manufacturing the organic EL element.

  Organic EL elements are attracting attention as an excellent flat panel from the viewpoint of color reproducibility and response speed, and development is progressing toward a larger screen. The organic EL element is composed of two electrodes (an upper electrode and a lower electrode) and an organic film sandwiched between the two electrodes. When a voltage is applied between the two electrodes, the organic film emits light.

In the manufacture of a general organic EL element, first, the first electrode is separated on a pixel-by-pixel basis on a supporting substrate such as glass corresponding to each color of red, green, and blue (RGB).
Next, an organic film made of at least an organic light emitting material is prepared by a vapor deposition method or the like. Usually, the organic film corresponding to each color of RGB is deposited by using a metal mask having openings corresponding to the respective colors.
Next, a second electrode is formed on the organic film by vapor deposition or the like.

  After the production of the second electrode, a target organic EL element is obtained by providing a sealing substrate via a protective film, an adhesive layer, or the like.

Here, in the case of an element that extracts light from the support substrate side (bottom emission type), the first electrode on the support substrate side is made of a light transmissive material, and the second electrode on the side opposite to the support substrate is a light reflective material (for example, a metal). Film).
In the case of an element that extracts light from the side opposite to the support substrate (top emission type), the first electrode is made of a light reflecting material, and the second electrode is made of a light transmitting material.

There are a passive matrix method and an active matrix method for driving organic EL elements. The active matrix method has excellent characteristics such as a short response time and high resolution.
In the case of this active matrix method, since the TFT element is formed between the first electrode and the substrate, the element structure of the top emission type can increase the aperture ratio and is suitable for a larger screen.

On the other hand, as the display screen becomes larger and the pixel size becomes smaller, it becomes difficult to produce a metal mask used for producing an organic film, and the limit of processing accuracy is pointed out. Therefore, there is a tendency that the organic film is formed by a so-called solid film in which the organic film is deposited without a mask.
Further, in the case of the top emission type, as described above, the second electrode needs to be made of a transparent or translucent light transmissive material. However, ITO (Indium Tin), which is a commonly used light transmissive electrode, is required. Oxide and other oxide films and metal thin films may cause damage to the organic film during fabrication by sputtering, resulting in deterioration of the display quality of the organic EL element, and voltage drop when the screen is enlarged due to high resistance. The problem arises that the image intensity is lowered due to the difference in the light emission intensity between the central portion and the peripheral portion of the screen.

Therefore, it is required to form the upper electrode without damaging the organic film and reduce the substantial resistance of the upper electrode.
On the other hand, a third electrode serving as an auxiliary electrode is formed on the same plane as the lower electrode, that is, the first electrode so as to have the same height as the position where the upper electrode is finally formed. A method of making contact with the upper electrode, that is, the second electrode on the side surface of the electrode (see, for example, Patent Document 1), a method of directly stacking auxiliary wiring on the upper electrode (see, for example, Patent Document 2), and the like have been proposed.
JP 2001-230086 JP 2004-281402 A

However, the method of making contact with the side surface of the auxiliary electrode fabricated on the same plane as the lower electrode is that the organic film is deposited on the surface of the auxiliary electrode when the organic film is deposited by the maskless method described above. Or, since it is covered, the contact between the upper electrode and the auxiliary electrode becomes impossible or unstable.
In this method, for example, even when the auxiliary electrode is formed in an overhang shape, it is difficult to suppress the adhesion of the organic film to the auxiliary electrode as long as the organic film is deposited after the auxiliary electrode is formed. There is a risk that the contact, that is, electrical connection, may be hindered, and forming the overhang shape to be extremely wide also makes it difficult to attach the electrodes and also causes a problem in achieving high definition of the element.

On the other hand, as the method of laminating the auxiliary electrode directly on the upper electrode, as the large screen and high definition progress, the accuracy of the vapor deposition mask becomes the same as the organic film described above, and the patterning of the auxiliary electrode becomes impossible. .
Furthermore, patterning the upper electrode or the organic film by a technique such as lithography is not preferable because the organic layer is damaged by a solvent, moisture, or the like.

  The present invention has been made in view of the above situation, and an object of the present invention is to form an upper electrode with good display quality without damaging the organic film, and to substantially form the upper electrode. Another object of the present invention is to provide an organic EL element and a display device in which a significant reduction in resistance is achieved, and a method for manufacturing an organic EL element in which substantial resistance of an upper electrode thereof is avoided while avoiding damage to an organic film.

  An organic EL device according to the present invention is an organic EL device having a first electrode, a second electrode, and an organic film made of at least an organic light-emitting material provided between the first and second electrodes, A protective film is formed on the second electrode, and a third electrode electrically connected to the second electrode is formed on the protective film.

  The display device according to the present invention is a display device having an organic EL element, wherein the organic EL element is provided between a first electrode, a second electrode, and the first and second electrodes, and is at least organic. A protective film is formed on the second electrode, and a third electrode electrically connected to the second electrode is formed on the protective film. It is characterized by having.

  The organic EL device manufacturing method according to the present invention includes a step of forming a first electrode, an organic film made of at least an organic light-emitting material, and a second electrode on a substrate, and protecting the second electrode. The method includes a step of forming a film and a step of forming a third electrode connected to the second electrode on the protective film.

  According to the organic EL device of the present invention, the protective film is formed on the second electrode serving as the upper electrode, and the third electrode, that is, the auxiliary electrode electrically connected to the second electrode is formed on the protective film. Since it has the formed configuration, it is possible to provide an organic EL element in which the second electrode and the third electrode can be satisfactorily contacted, and the voltage drop is suppressed and the image quality is maintained or improved.

  In the organic EL device according to the present invention, at least a part of the third electrode is formed corresponding to the peripheral edge of the pixel, or formed on the entire surface of the pixel but made of a light transmitting material. Thus, characteristics such as the brightness and contrast of the light extracted to the outside can be secured, and a display device having better display quality and display quality can be configured.

  According to the method for manufacturing an organic EL element according to the present invention, a step of forming a first electrode, an organic film, and a second electrode on a substrate, and a step of forming a protective film on the second electrode; And forming a third electrode connected to the second electrode on the protective film, so that the organic EL element in which the substantial resistance of the second electrode is reduced without damaging the organic film. Can be manufactured.

  In the method for manufacturing an organic EL element according to the present invention, the protective film is formed as a multilayer film including two or more layers having different etching resistances, and a part of the protective film is formed prior to the formation of the third electrode. By selectively etching to form a contact hole, it is possible to form a good contact between the second electrode and the third electrode while avoiding damage to the organic film.

  Embodiments of the present invention will be described below with reference to the drawings.

First, embodiments of an organic EL element and a display device according to the present invention will be described.
As shown in FIGS. 1A and 1B, the organic EL element 1 according to the present embodiment includes, on a substrate 2 made of glass, for example, at least a first electrode 3 and an organic film 4 made of at least an organic light emitting material, The first and second protective films 6 and 7 are formed as a laminated film on the second electrode 5, and the second electrode 5 is electrically connected to the second electrode 5. It has a configuration in which three electrodes 8 are formed.
Although not shown, an adhesive resin and a sealing substrate are formed on the third electrode 8 and the second protective film 7 exposed in the opening so as to cover these and the side surface of the organic EL element 1. Is preferred.

In the organic EL element 1 according to this embodiment, the first electrode 3 is an anode, the second electrode 5 is a cathode, and light emission from the organic film 4 is taken out from the second electrode 5 side to the outside. It has an emission type configuration.
Further, in the organic EL element 1 according to this embodiment, a TFT (Thin Film Transistor) (not shown) is provided between the substrate 2 and the first electrode 3, and the first electrode is driven by this TFT element. Active matrix type.

  The first electrode 3 includes a plurality of pixels constituting the organic EL element 1 via the insulating film 12 between the TFT wiring 11 and the first electrode constituting adjacent pixels. Corresponding to every 10, it can be made of a light reflecting material that reflects light emitted from the organic film 4, for example, aluminum (Al).

The organic film 4 is made of at least an organic light emitting material. For example, although not shown, the organic film 4 has a hole transport layer on the first electrode side and an electron transport layer on the second electrode side with a light emitting layer made of the organic light emitting material as the center. be able to. Further, one of the hole transport layer and the electron transport layer can also serve as the light emitting layer.
In the present embodiment, the organic film 4 is formed as a so-called solid film in common for adjacent pixels 10.

  The second electrode 5 is formed on the organic film 4 in common for the adjacent pixels 10, but is composed of a light-transmitting material that transmits light emitted from the organic film 4, for example, the above-described Mg—Ag mixed film. A light transmissive thin film is used.

As will be described later, the first and second protective films 6 and 7 preferably constitute the second protective film 7 with a material having higher etching resistance than the first protective film 6. A light transmissive material that transmits light emitted from the film 4 is formed of, for example, SiN _X and SiO _X, respectively.

The third electrode 8 is made of, for example, Al, and has a contact portion 9 in a contact hole formed in the first and second protective films, and is electrically connected to the second electrode by the contact portion 9.
The third electrode is mainly formed corresponding to the peripheral edges of the plurality of pixels 10 and has a position shape that does not inhibit light emission generated in the organic film 4 in each pixel 10. That is, the third electrode 8 is formed so as to surround each unit pixel 10 or a plurality of pixels 10.

The contact portion 9 can be provided in the entire formation portion of the third electrode 8, but can be formed by selecting a desired position shape in the peripheral portion of the plurality of pixels 10, that is, in the inter-pixel portion.
For example, as shown in FIG. 2A, the third electrode 8 extending in the horizontal direction and the third electrode 8 extending in the vertical direction are formed in the inter-pixel portions of the plurality of pixels 10 provided in a lattice shape. It can be provided at all intersections, or as shown in FIG. 2B, contact holes can be thinned out and provided at every other intersection. Further, as shown in FIG. 2C, the pixel 10 may be provided in a so-called staggered pattern only at the intersection located on one diagonal.

Further, the third electrode 8 does not necessarily need to be formed to cover all the pixels 10, and has a density that can sufficiently reduce the substantial resistance of the second electrode 5 and suppress the voltage drop, for example, as shown in FIG. As shown in 2D, it may be formed in every other inter-pixel portion.
It is preferable that the 3rd electrode 8 used as the auxiliary electrode of the 2nd electrode 5 has high electroconductivity compared with a 2nd electrode. In order to make the conductivity higher than that of the second electrode, a material having a specific resistance smaller than that of the second electrode may be used, or while using a material having a specific resistance equal to or larger than that of the second electrode. Alternatively, the substantial resistance may be reduced by forming it thicker than the second electrode.

  According to the organic EL element according to the present embodiment, the protective film is formed on the second electrode serving as the upper electrode, and the third electrode that is electrically connected to the second electrode, that is, the auxiliary electrode, is formed on the protective film. Since it has the structure in which the electrode was formed, the 2nd electrode and the 3rd electrode can be satisfactorily contacted, and an organic EL element in which the voltage drop is suppressed can be provided.

  Further, in the organic EL element according to the present embodiment, characteristics such as brightness and contrast of light extracted outside are obtained by forming at least part of the third electrode corresponding to the periphery of the pixel. Can be ensured, and a display device having better display quality and display quality can be configured.

In the present embodiment, the light reflecting material described above may be a material having a higher reflectance with respect to the wavelength of light generated in the organic film than at least the light transmitting material. Even if it is not transparent, it may be translucent, for example.
Further, the peripheral edge refers to, for example, at least a part between a plurality of arranged pixels and does not necessarily have a shape that completely surrounds the periphery of the pixels.

  Next, an embodiment of a method for producing an organic EL element according to the present invention will be described.

  First, as shown in FIG. 3A, a substrate 2 made of glass is prepared, and a TFT element 15 made of a wiring 11 that becomes a TFT gate electrode, a gate insulating film 21, and a semiconductor thin film 20 is formed thereon, A flattened insulating film made of, for example, PI is formed thereon via an insulating film 12 made of, for example, polyimide (PI), and the TFT element 15 is formed on a predetermined portion of the flattened insulating film using a resist pattern formed by lithography as a mask. After forming the concave portion including the contact hole that communicates, an electrode material, such as Al, that finally forms the first electrode (pixel electrode, so-called lower electrode) 3 is formed by sputtering to a thickness of, for example, 100 nm. Each pixel is patterned by photolithography and etched by mixed acid (nitric acid, acetic acid and phosphoric acid) or chlorine gas. After forming the first electrode 3 to be configured, in order to prevent a short circuit between the first electrodes 3 configuring adjacent pixels, insulation is performed by, for example, PI across the end portion of the first electrode 3 and the exposed portion of the insulating film 12. An interlayer insulating film 13 is formed by forming a film.

  Subsequently, as shown in FIG. 3B, for example, by a vapor deposition method, a common film, that is, a solid film for a plurality of pixels across the first electrode 3 and the exposed portion of the interlayer insulating film 13, for example, with a thickness of 50 nm to 100 nm. An organic film 4 is formed. Although not shown, the organic film 4 has at least a light emitting layer made of an organic light emitting material. If necessary, a hole transport layer is formed on the first electrode 3 side, and an electron transport layer is formed on the second electrode 5 side to be formed later. Can be appropriately changed. Various materials can be used according to the target emission wavelength.

  Subsequently, as shown in FIG. 3C, a second electrode (opposite electrode, so-called upper electrode) 5 made of, for example, a Mg—Ag mixed film is entirely formed on the upper surface of the organic film 4 by a vapor deposition method, for example, with a thickness of 10 nm. By forming the first electrode 3, the organic film 4, and the second electrode 5 are stacked.

Subsequently, as shown in FIG. 4A, for example, a first protective film 6 made of, for example, SiN _X and a second protective film 7 made of, for example, SiO _{X are formed} by, for example, CVD (Chemical Vapor Deposition), for example, respectively. After the layers are formed with a thickness of 3 μm and 1 μm, a resist 14 having an opening is formed by a lithography method at a predetermined position between the elements, that is, at a position where the contact portion 9 is finally formed.

Subsequently, as shown in FIG. 4B, the second protective film 7 exposed in the opening of the resist 14 is etched. For example, a dry etching method and a wet etching method can be applied to the etching here. For example, a mixed liquid of HF (hydrogen fluoride or hydrofluoric acid) and NH ₄ F, or a mixed gas of CF ₄ gas and H ₂ gas is used. Can be used.

Subsequently, as shown in FIG. 4C, the first protective film 6 is etched using the second protective film 7 as a mask. As the etching method, either a dry etching method or a wet etching method can be applied. However, since the second electrode 5 is formed in a thin film shape, in order to avoid damage to the organic film 4 more reliably, moisture can be used. It is preferable to use a dry etching method that does not use the above. The etching here can be performed using, for example, HF (hydrogen fluoride or hydrofluoric acid) or CF ₄ gas.
Here, since the second protective film 7 serves as a mask for etching the first protective film 6, the second protective film 7 is preferably made of a material having higher etching resistance than the first protective film 6.

  Subsequently, as shown in FIG. 5A, the third electrode 8 made of, for example, Al serving as the auxiliary electrode of the second electrode 5 is formed over the entire surface including the contact portion 9 with the second electrode 5, and then the second electrode 5 is formed. A resist 17 is formed by lithography on the peripheral edge of each pixel of the three electrodes 8, that is, between the pixels.

Subsequently, as shown in FIG. 5B, the portion exposed to the opening of the resist 17 of the third electrode 8 is removed by etching, leaving the peripheral portion of each pixel, that is, the inter-pixel portion, and then the resist 17 is peeled off. Thus, an organic EL element 1 as shown in FIGS. 1A and 1B is obtained.
As the etching method of the third electrode 8, either a dry etching method or a wet etching method can be applied, but it is preferable to use a dry etching method that does not use moisture or the like.

  As shown in FIG. 6, after removing the resist 17, the adhesive resin is formed so as to cover the third electrode 8 and the second protective film 7 exposed in the opening so as to cover these and the side surface of the organic EL element 1. 18 and the sealing substrate 19 can also be formed.

  According to the method for manufacturing an organic EL element according to the present embodiment, a step of forming a first electrode, an organic film, and a second electrode on a substrate, and a step of forming a protective film on the second electrode. And a step of forming a third electrode connected to the second electrode on the protective film, and thus the organic EL element in which the substantial resistance of the second electrode is reduced without damaging the organic film Can be manufactured.

  In the method of manufacturing the organic EL element according to the present embodiment, the protective film is formed as a multilayer film including two or more layers having different etching resistances, for example, and a part of the protective film is used for forming the third electrode. By selectively etching in advance to form a contact hole, a good contact can be formed between the second electrode and the third electrode while avoiding damage to the organic film.

  In addition, the manufacturing method of the organic EL element which concerns on this invention, a display apparatus, and an organic EL element is not restricted to this embodiment.

For example, the material constituting the third electrode 8, that is, the auxiliary electrode is not limited to Al, and any material having a low resistance such as silver (Ag), copper (Cu), tungsten (W) can be applied.
Further, for example, as shown in FIG. 7, the third electrode is formed on the entire surface of each pixel 10, but is made of a light transmitting material, so that the brightness, contrast, etc. of the light extracted outside the organic EL element are increased. The characteristics can be ensured, and a display device having better display quality and display quality can be configured. In this case, ITO or the like can be used as the light transmitting material.

  In addition, for example, in the present embodiment, an example of a top emission type, that is, a top emission type organic EL element has been described. Not only the active matrix system but also a passive matrix system can be used.

Moreover, the material which comprises a 1st electrode, ie, a lower electrode, is not restricted to Al, It is applicable if it is highly reflective metals, such as Ag.
Further, the material constituting the insulating film is not limited to PI, and other organic materials and oxide films such as SiO ₂ can also be applied.
Further, the material constituting the second electrode, that is, the upper electrode is not limited to the Mg—Ag mixed film, and for example, a very thin light-transmitting material such as Al or ITO is applicable.
Further, the material constituting the first and second protective films is not limited to SiO _X and SiN _X , and a reverse combination or a material such as Al ₂ O ₃ is also applicable. Further, even if the first protective film and the second protective film are made of the same material, if the etching resistance is different, for example, by making the composition ratios different from each other, the structure is made of the same material. It is also possible.

  In the present embodiment, the first electrode is an anode and the second electrode is a cathode. However, the present invention can be modified and modified in various ways, such as a configuration in which these are reversed.

1A and 1B are a schematic perspective view showing a configuration of an example of an organic EL element according to the present invention, and a schematic perspective view with a part in cross section. A to D are schematic views illustrating configuration examples of a third electrode, a contact portion, and a pixel, respectively, of the organic EL element according to the present invention. It is process drawing with which it uses for description of an example of the manufacturing method of the organic EL element which concerns on AC. It is process drawing with which it uses for description of an example of the manufacturing method of the organic EL element which concerns on AC. It is process drawing with which it uses for description of an example of the manufacturing method of the organic EL element concerning this invention. It is a schematic sectional drawing which shows the structure of the other example of the organic EL element which concerns on this invention. It is a schematic sectional drawing which shows the structure of the other example of the organic EL element which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Organic EL element, 2 ... Substrate, 3 ... 1st electrode (lower electrode, pixel electrode), 4 ... Organic film, 5 ... 2nd electrode, 6 ... 1st Protective film, 7 ... 2nd protective film, 8 ... 3rd electrode, 9 ... Contact part, 10 ... Pixel, 11 ... TFT wiring, 12 ... Insulating film, 13 ... Interlayer insulating film, 14 ... resist, 15 ... TFT element, 16 ... contact hole, 17 ... resist, 18 ... resin, 19 ... sealing substrate, 20 ... semiconductor Thin film, 21 ... gate insulating film

Claims (16)

An organic EL device having a first electrode, a second electrode, and an organic film provided between at least the first and second electrodes and made of at least an organic light-emitting material,
A protective film is formed on the second electrode;
An organic EL element, characterized in that a third electrode electrically connected to the second electrode is formed on the protective film. The organic EL element according to claim 1, wherein the connection between the third electrode and the second electrode is selectively performed at a peripheral portion of the pixel. The organic EL element according to claim 1, wherein the third electrode and the second electrode are connected in a contact hole formed in the protective film. The organic EL element according to claim 1, wherein the third electrode is formed at least partially corresponding to the periphery of the pixel. The organic EL element according to claim 1, wherein the third electrode is made of a light transmitting material. The organic EL element according to claim 1, wherein the third electrode exhibits higher conductivity than the second electrode. The organic EL element according to claim 1, wherein the protective film is a multilayer film having at least two layers. The organic EL element according to claim 1, wherein the organic film is formed at least partially in common between adjacent pixels. The organic EL element according to claim 1, wherein the first electrode is made of a light reflecting material, and the second electrode is made of a light transmitting material. A display device having an organic EL element,
The organic EL element is
A first electrode, a second electrode, and an organic film provided between the first and second electrodes and made of at least an organic light-emitting material;
A protective film is formed on the second electrode;
A display device having a configuration in which a third electrode electrically connected to the second electrode is formed on the protective film. Forming a first electrode, an organic film made of at least an organic light emitting material, and a second electrode on the substrate;
Forming a protective film on the second electrode;
Forming a third electrode connected to the second electrode on the protective film. A method of manufacturing an organic EL element, comprising: The method of manufacturing an organic EL element according to claim 11, wherein a part of the protective film is selectively etched prior to the formation of the third electrode. The method of manufacturing an organic EL element according to claim 11, wherein the third electrode is formed at least partially corresponding to the periphery of the pixel. The method for manufacturing an organic EL element according to claim 11, wherein the third electrode is made of a light transmitting material. The method for producing an organic EL element according to claim 11, wherein the protective film is formed as a multilayer film having at least two layers. The method of manufacturing an organic EL element according to claim 11, wherein the organic film is formed in common for at least a part of adjacent pixels.

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