KR20060100057A - Organic electro-luminescence device with photo-luminescence layer and display panel comprising the same - Google Patents

Abstract

Disclosed are an organic electroluminescent device having an electrode structure advantageous for large screen implementation, and an organic electroluminescent display panel composed thereof. The light emitting device is a transparent glass substrate, a metal anode formed on the transparent glass substrate and having an opening, an organic electroluminescent laminate structure in contact with the anode, and at least including an electron transport layer and a hole transport layer, the organic electroluminescent laminate structure A photo luminescence layer formed at a position corresponding to the opening therein and emitting secondary light excited from light generated in the organic electroluminescent laminate structure and a metal cathode formed on the organic electroluminescent laminate structure It is characterized by.

Organic electroluminescent element, photoluminescence, metal anode, openings, mesh

Description

Organic electroluminescent element provided with photoluminescence layer, organic electroluminescent display panel {ORGANIC ELECTRO-LUMINESCENCE DEVICE WITH PHOTO-LUMINESCENCE LAYER AND DISPLAY PANEL COMPRISING THE SAME}

1 is a cross-sectional view showing the structure of a conventional organic electroluminescent device.

2 is a cross-sectional view schematically showing the structure of an organic EL device according to a first embodiment of the present invention.

3 is a cross-sectional view showing the structure of an organic EL device according to a second embodiment of the present invention.

4 is a diagram showing a cross-sectional structure of an organic EL device according to a third embodiment of the present invention.

5 is a cross-sectional view illustrating a structure of an organic EL device according to a fourth embodiment of the present invention.

<Brief description of the symbols in the drawings>

100: transparent substrate 110: metal anode

112: opening 120: organic electroluminescent laminated structure

121: hole injection layer 123: hole transport layer

124 photoluminescence layer 125 electroluminescent layer

127: electron transport layer 129: electron injection layer

130: metal cathode

The present invention relates to an organic electroluminescent display panel, and more particularly, to an organic electroluminescent device having an electrode structure advantageous for implementing a large screen, and an organic electroluminescent display panel composed of the same.

The organic electroluminescent device is a device in which electrons and holes injected through a cathode and an anode are formed into excitons in a monomolecular or polymer organic thin film, and light of a specific wavelength is generated from the formed excitons. The organic material layer such as an electron transport layer and the cathode are laminated.

The organic electroluminescent display in which the organic light emitting diodes are arranged in the form of a matrix inside the panel has advantages such as low voltage driving, high luminous efficiency, high viewing angle, and fast response speed. As one of the technologies, the development of technology for commercialization is actively underway.

An organic electroluminescent display generally includes a plurality of transparent anodes formed in parallel on a substrate, a pixel region on a grid formed on the anode and partitioning the plurality of regions, and an organic light emitting layer formed on the pixel regions. And an organic light emitting material layer and a plurality of cathodes formed on the organic light emitting material layers and orthogonal to the anode.

In this case, a transparent oxide conductive material such as indium tin oxide (ITO) is used as the anode material. However, indium tin oxide has a very high resistance compared to metal electrodes. As described above, in a state where the electrode resistance is high, a voltage drop causes uneven distribution of potentials in the display, and causes a problem in that luminance between light emitting elements becomes irregular.

In order to solve this problem, Japanese Patent Laid-Open No. Hei 4-254887 has attempted to improve the disadvantage of low resistance of the transparent electrode by adding a bus electrode made of metal to the transparent electrode. However, this technique has a problem that the amount of light emitted from the organic light emitting layer due to the metal electrode is reduced due to the metal electrode, which in turn lowers the luminance of the device.

In order to solve this problem, Japanese Patent Laid-Open No. 2002-170688 has proposed a bus electrode structure having an opening for extracting light of the light emitting layer to the outside in order to prevent a decrease in luminance due to the bus electrode.

1 is a cross-sectional view showing the structure of an organic electroluminescent device proposed by the Japanese Laid-Open Patent Publication. Referring to FIG. 1, the organic EL device 1 includes a metal layer 3 having an opening on a transparent glass substrate 2, and a transparent conductive film 4a such as ITO laminated while covering the metal layer. The anode 4, the organic electroluminescent layer 5, and the cathode 6 are laminated on the organic electroluminescent layer 5. The organic electroluminescent layer 5 has a structure in which a hole transport layer 51 and an electron transport layer 52 serving as a light emitting layer are stacked. The metal layer 3 has an opening 3a corresponding to the pixel so that the light emitted from the light emitting layer 5 escapes.

However, the organic EL device having such a structure still has a problem of lowering the luminance of the light emitting device. First, an electric field applied between the metal layer 3 and the cathode 6 is concentrated on a part of the light emitting layer 5. That is, since the electric field applied to the light emitting layer 5 facing the opening 3a is insignificant, only a part of the light emitting layer 5 emits light, resulting in a decrease in luminance. In addition, while the light emitted from the region exits through the opening, the light intensity may be reduced due to reflection or scattering. In addition, since the transparent conductive film 4a is present on the metal layer 3 in the above structure, the amount of light that is transmitted is inevitably reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and an object thereof is to provide an organic electroluminescent device which is advantageous for large area while minimizing a decrease in luminance.

It is also an object of the present invention to provide an organic electroluminescent display panel which improves the unevenness of the potential distribution and irregularities of luminance of individual light emitting elements in the panel.

In order to achieve the above technical problem, the present invention provides a transparent glass substrate, a metal anode formed on the transparent glass substrate and having an opening, an organic electroluminescent layered structure in contact with the anode and including at least an electron transport layer and a hole transport layer, The photoluminescence layer is formed at a position corresponding to the opening in the organic electroluminescent laminate structure, and is formed on the photoluminescence layer and the organic electroluminescent laminate structure that emit secondary light excited from light generated in the organic electroluminescent laminate structure. It provides an organic electroluminescent device comprising a metal cathode.

In the device, the organic electroluminescent structure preferably has a stacked structure of a hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer.

The photo luminescence layer may be coplanar with the emission layer. Alternatively, the photo luminescence layer may be present above or below the light emitting layer.

In the device of the present invention, the light emitting layer may be made of ADN, and the material of the photoluminescent layer may be Alq3 doped with DCJTB. In addition, the light emitting layer may be made of ADN, and the material of the photo luminescence layer may be ADN doped with perylene. In addition, the material of the light emitting layer is ADN, the material of the photo luminescence layer may be Alq3 doped with C-545T.

Further, in the device of the present invention, the organic electroluminescent structure may have a stacked structure of a hole transport layer / electron transport layer. In this case, the photo luminescence layer may be present on the same plane as the hole transport layer or above or below the hole transport layer.

The present invention also provides an organic electric field comprising a transparent glass substrate, a plurality of anodes and cathodes formed on the transparent glass substrate, and an organic electroluminescent laminated structure formed on a plurality of pixels defined by the plurality of anodes and cathodes. In the light emitting display panel, an opening is provided in any one of the anode and the cathode defining each of the pixels, and the organic electroluminescent layer structure is excited by light emitted by the organic electroluminescent layer structure therein. An organic electroluminescent display panel comprising a photoluminescence layer for emitting secondary light, wherein the photoluminescence layer spans at least a region corresponding to the opening.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings below refer to the same or similar configurations. In addition, the dimension and shape of each layer which comprise the organic electroluminescent element of this invention shown in the following drawings do not necessarily limit embodiment of the element structure of this invention.

2 is a cross-sectional view schematically showing the structure of an organic EL device according to a first embodiment of the present invention.

Referring to FIG. 2, the device includes a transparent glass substrate 100, a metal anode 110, an organic EL layer 120, and a metal cathode 130. The metal anode 110 includes an opening 122 that provides a passage path for light generated from the organic EL layer 120, particularly the light emitting layer 125. In addition, the device is provided with a photo luminescence layer 124 inside the organic electroluminescent layer structure 120.

In the present invention, the material of the metal anode 110 may be a conventional electrode material such as aluminum. The metal anode may be patterned by conventional methods such as vapor deposition and photolithography, and the implementation of the metal anode having such an opening is obvious to those skilled in the art to which the present invention pertains, and thus will not be described herein.

As the cathode material, an active metal or a metal alloy having a low work function such as Mg, Ag, MgAg-Li, LiAl, LiF-Al, or the like is used, and may be formed by vacuum deposition using a metal shadow mask.

As illustrated, the organic EL layer 120 may include a hole injection layer 121, a hole transport layer 123, a light emitting layer 125, an electron transport layer 127, and an electron injection layer 129. Can be. Of course, the organic electroluminescent layer structure may be implemented by only the hole transport layer 123 and the electron transport layer 127.

The deposition of the organic material may be performed by conventional vacuum thin film deposition using a fine metal shadow mask, and includes the hole injection layer 121, the hole transport layer 123, and the electrons constituting the organic electroluminescent material stack 120. The laminated material constituting the transport layer 127 and the electron injection layer 129 will be apparent to those skilled in the art to which the present invention pertains.

In the present invention, materials constituting the light emitting layer 215 and the photo luminescence layer 214 may be appropriately designed by those skilled in the art who understand the technical spirit of the present invention described later. That is, when the light emitting device is a red light emitting device, the material of the electroluminescent layer 214 is composed of a material that emits light in the ultraviolet or visible light region by an applied electric field, and the photo luminescence layer 214. The phosphor may be excited by the incident light from the electroluminescent layer 214 to exhibit a red spectrum in the visible light region, or the phosphor mixed with the incident light to exhibit a red spectrum may be used. The same applies to the green light emitting element and the blue light emitting element.

For example, when the light emitting device of the present invention is a red light emitting device, ADN (9,10-di- (2-naphthyl) antracene) is converted into the photoluminescence layer 214 as the electroluminescent layer 215. Organics with DCJTB as the dopant for the Alq3 host can be used.

When the light emitting device is a green light emitting device, an organic material doped with ADN as the electroluminescent layer 215 and C-545T doped in an Alq3 host may be used as the photoluminescence layer 214.

In addition, when the light emitting device is a blue light emitting device, a material doped with ADN as the electroluminescent layer 215 and perylene doped with an ADN host may be used as the photoluminescence layer 214. .

Referring back to FIG. 2, a photo luminescence layer 124 is provided inside the organic EL layer 120. As shown, the photo luminescence layer 124 is disposed coplanar with the electroluminescent layer 125.

Hereinafter, the light emitting mechanism of the organic electroluminescent device of the present invention will be described.

The organic electroluminescent device of the present invention has a light emitting layer of two different compositions. That is, the first light emitting layer is an electroluminescent layer 215, which emits light by recombination of electrons and holes injected by an electric field applied between the anode and the cathode. The second light emitting layer is a layer that is excited by the light generated from the electroluminescent layer (including ultraviolet rays, which is the same below) and emits light. The second light emitting layer is a photoluminescence layer 214 that emits secondary light.

As shown in FIG. 2, in the device structure of the present invention, since the opening 112 is formed at the center of the anode, the portion where the electric field is concentrated between the anode and the cathode is the peripheral side of the device, and the EL layer 125 is disposed. In addition, a photo luminescence layer 124 is disposed at a central portion corresponding to an opening of the anode between the anode and the cathode. The photo luminescence layer 124 is excited from the light generated from the electroluminescent layer 125 to generate secondary light. Primary light emitted from the electroluminescent layer 125 is reflected or scattered in the organic electroluminescent laminated structure, and the light incident on the photo luminescent layer 124 is reflected or scattered to the photo luminescent layer ( 124 is excited to generate secondary light. The secondary light generated in this way is emitted to the outside through the opening between the anode.

2 described above does not employ a transparent electrode such as ITO. Therefore, it is possible to provide an organic EL device having a low loss of luminance due to the transmittance limit of the transparent electrode. In addition, the device of the present invention includes a photo luminescence layer 124 and emits light emitted from the electroluminescent layer 125 to scatter light inside the device as an energy source to obtain photo luminescence emission. Therefore, it is possible to reduce the energy lost due to scattering of light, thereby suppressing the decrease in luminance.

Moreover, the electroluminescent display device formed of the matrix of the device structure of the present invention uses a metal material such as aluminum as the anode material. Metal materials such as aluminum have a much lower resistance value than transparent electrodes such as ITO, thereby alleviating uneven distribution of potentials between the individual elements constituting the display, thereby suppressing luminance irregularities between the individual pixels constituting the display. . Therefore, the above-described organic electroluminescent device structure of the present invention is suitable to be implemented as a basic unit of a display having a large area.

3 is a cross-sectional view showing the structure of an organic EL device according to a second embodiment of the present invention.

Referring to FIG. 3, an anode 110 having an opening formed on a transparent glass substrate 100, a hole injection layer 121 made of an organic material, a hole transport layer 123, a light emitting layer 125, an electron transport layer 127, and The electron injection layer 129 is formed. In addition, a photo luminescence layer 124 is formed on the hole transport layer 123.

Unlike the description with reference to FIG. 2, the photo luminescence layer 124 is not formed on the same plane as the emission layer 125 but is formed in a vertical relationship. Although FIG. 3 shows the photo luminescence layer 124 below the light emitting layer 125, the photo luminescence layer 124 may be present above the light emitting layer 125. .

The operating mechanism of the device structure of FIG. 3 is similar to that of the organic electroluminescent device described with reference to FIG. 2. In the device of FIG. 3, two light emitting layers, that is, the electroluminescent layer 125 and the photo luminescence layer 124, exist and emit light according to respective light emitting mechanisms. The light emission of the electroluminescent layer 125 is mainly activated at the periphery of the device where the electric field is concentrated, and the light emission of the photo luminescence layer 124 occurs over the entire device. Light emitted from the photoluminescence layer 124 is emitted to the outside of the transparent glass substrate through the opening of the anode 110.

4 is a diagram showing a cross-sectional structure of an organic EL device according to a third embodiment of the present invention.

Referring to FIG. 4, similar to FIG. 3, the anode 110 having the opening on the transparent glass substrate 100, the hole injection layer 121, the hole transport layer 123, the light emitting layer 125, and the electron transport layer 127 are provided. And the electron injection layer 129 are sequentially stacked. In addition, a photo luminescence layer 124 is formed between the hole transport layer 123 and the light emitting layer 125 as shown. However, unlike the structure of FIG. 3, the photoluminescence layer 124 is formed to be limited to a portion corresponding to the opening 112 in the device. Of course, in the present embodiment, the photo luminescence layer 124 may be formed on the light emitting layer 125.

5 is a cross-sectional view illustrating a structure of an organic EL device according to a fourth embodiment of the present invention.

Referring to FIG. 5, a trench structure is formed in the transparent glass substrate 100 around the device. A metal anode 110 is formed in the trench structure. The protrusion of the transparent glass substrate 100 naturally protruding by the trench structure plays the same role as the opening 112 described above. In the structure of FIG. 5, the organic EL layer 120 except for the trench structure is similar to that of FIG. 2. However, the present embodiment is different from FIG. 2 in that the flatness of the organic EL layer 120 is ensured since the opening is not recessed.

Of course, although not separately illustrated, the organic electroluminescent layer 125 and the photo luminescence layer 124 illustrated in FIGS. 3 and 4 may be formed on the trench structure of FIG. 5.

Although the above-described embodiments of the present invention have described the case in which the opening is formed on the anode, it will be understood by those skilled in the art that the opening may be formed on the cathode.

In addition, in the above-described embodiments of the present invention, the metal anode of the device has one opening, but the number of openings formed in the metal anode is not limited thereto, and may include a plurality of openings. For example, a metal mesh having a plurality of openings may be used as the metal anode.

In addition, the above-described electroluminescent device of the present invention can implement red (R), green (G) and blue (B) can be applied to a display panel in which the individual electroluminescent devices are arranged in a matrix form.

In this case, a plurality of anodes 110 and cathodes 130 defining individual pixel formation regions are formed on the transparent substrate 100, and the anodes and the cathodes are connected to an external power source through a pad region. Individual pixels defined by the anode 110 and the cathode 130 may be configured as basic units of the organic EL device described with reference to FIGS. 2 to 5.

Preferred embodiments of the present invention described above are merely illustrative of embodiments of the present invention, and can be modified and applied in various forms within the scope of the technical spirit of the present invention described above. In addition, the embodiments and drawings are used for the purpose of describing the contents of the present invention in detail, and are not intended to limit the technical scope of the present invention. Therefore, one of ordinary skill in the art to which the present invention pertains will be able to make various substitutions and modifications based on the above-described embodiments and the accompanying drawings without departing from the spirit of the present invention. The scope of the invention should be construed to include the claims and their equivalents as well as the claims that follow.

The organic electroluminescent device of the present invention does not use a conventional transparent electrode and adopts a photo luminescence layer to reduce the loss of light, thereby maximally suppressing a decrease in luminance of the device.

In addition, the organic electroluminescent display panel using the organic electroluminescent element of the present invention as a basic structural unit, by using a low-resistance metal electrode in place of the existing transparent electrode to alleviate the uneven distribution of the potential distribution between individual light emitting elements in the panel, This suppresses the luminance irregularity between the individual pixels forming the display. Therefore, it is suitable for the implementation of an organic electroluminescent display having a large area.

Claims (14)

Transparent glass substrates; A metal anode formed on the transparent glass substrate and having an opening; An organic electroluminescent laminate structure in contact with the anode and including at least an electron transport layer and a hole transport layer; A photo luminescence layer formed at a position corresponding to the opening in the organic electroluminescent laminate structure and emitting secondary light excited from light generated in the organic electroluminescent laminate structure; And An organic electroluminescent device comprising a metal cathode formed on the organic electroluminescent laminate structure. The method of claim 1, The organic electroluminescent device has a laminated structure of a hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer. The method of claim 2, And the photo luminescence layer is coplanar with the light emitting layer. The method of claim 2, The photo luminescence layer is an organic electroluminescent device, characterized in that present above or below the light emitting layer. The method according to any one of claims 1 to 4, The material of the light emitting layer is ADN, the material of the photoluminescence layer is an organic electroluminescent device, characterized in that the AlJ3 doped with DCJTB. The method according to any one of claims 1 to 4, The material of the light emitting layer is ADN, the material of the photoluminescence layer is an organic electroluminescent device, characterized in that the ADN doped with perylene (perylene). The method according to any one of claims 1 to 4, The material of the light emitting layer is ADN, the material of the photoluminescence layer is an organic electroluminescent device, characterized in that the Al-q3 doped with C-545T. The method of claim 1, The organic electroluminescent device has an organic electroluminescent device, characterized in that it has a laminated structure of a hole transport layer / electron transport layer. The method of claim 8, And the photo luminescence layer is coplanar with the hole transport layer or above or below the hole transport layer. The method of claim 1, The metal anode is an organic electroluminescent device, characterized in that the mesh form. An organic electroluminescent display panel comprising a transparent glass substrate, a plurality of anodes and cathodes formed on the transparent glass substrate, and an organic electroluminescent laminate structure formed on a plurality of pixels defined by the plurality of anodes and cathodes. In An opening is provided in any one of the positive electrode and the negative electrode defining the respective pixels, The organic electroluminescent layered structure includes a photoluminescence layer excited therein by light emitted by the organic electroluminescent layered structure to emit secondary light, the photoluminescent layer corresponding to at least the opening. An organic electroluminescent display panel characterized by covering the area | region which becomes. The method of claim 11, And the light emitting layer includes ADN, and the photo luminescence layer includes Alq 3 doped with DCJTB. The method of claim 11, And the light emitting layer includes ADN, and the photo luminescence layer comprises ADN doped with perylene. The method of claim 11, The light emitting layer includes ADN, and the photo luminescence layer comprises Alq3 doped with C-545T.

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