Flat panel display device and method thereof

A flat panel display device including a display area where an image is displayed and a non-display area located at an outside of the display area includes bank portions arranged in a pattern in the display area and partitioning a plurality of openings, emission elements located in the openings, dummy bank portions formed in the non-display area and integrated therewith, and a sealing passivation layer having a multi-layered structure of organic films and inorganic films alternately arranged, one organic film being located at an interface directly contacting the emission element and one inorganic film located firstly on an outermost portion of the dummy bank portions when the sealing passivation layer extends from the display area to the non-display area.

This application claims priority to Korean Patent Application No. 10-2006-0003119, filed on Jan. 11, 2006 and all the benefits accruing therefrom under 35 U.S.C. §119, and the contents of which in its entirety are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flat panel display device and method thereof, and more particularly, to a flat panel display device preventing oxidation/corrosion due to harmful material such as oxygen/moisture and a method of fabricating the flat panel display device.

2. Description of the Related Art

FIG. 1is a cross-sectional view of a conventional flat panel display device and in particular, an organic light-emitting display device disclosed in Japanese Patent Publication No. 1999-121165. Referring toFIG. 1, on a substrate11, a first electrode layer21constituting an anode electrode injecting holes, an organic film25in which light is emitted by the recombination of holes and electrons, and a second electrode layer29constituting a cathode electrode injecting electrons are formed successively. Light is produced in the organic film25by the recombination of the holes injected from the first electrode layer21and the electrons injected from the second electrode layer29. The second electrode layer29injecting electrons is highly active and chemically unstable, and therefore reacts easily with moisture and oxygen of the outside air leading to oxidization and corrosion. With the permeation of moisture or oxygen into the organic film25, the emission characteristics of the organic film25degrade due to a change of crystalline structure and in an extreme case, dark spots are formed, adversely affecting a display function. Thus, in the conventional art, a double surrounding wall including inner wall31and outer wall35which surround emission layer25are formed to prevent the permeation of harmful material such as oxygen/moisture from the outside into the emission layer25. In the conventional art, an additional process of forming the surrounding wall is required so that manufacturing productivity is lowered, thereby causing a problem that the reliability of the product is deteriorated such as due to a bad sealing property of the wall.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a flat panel display device preventing the degradation of performance over a period of time by blocking the permeation of harmful material such as oxygen or moisture.

The present invention also provides a flat panel display device minimizing an additional process or an additional manufacturing cost.

The present invention also provides a method of fabricating the flat panel display device.

According to exemplary embodiments of the present invention, there is provided a flat panel display device including a display area where a desired image is displayed and a non-display area located at an outside of the display area. The flat panel display device includes bank portions arranged in a pattern in the display area and partitioning a plurality of openings, emission elements located in the openings, dummy bank portions formed in the non-display area and integrated with the bank portions, and a sealing passivation layer having a multi-layered structure of organic film and inorganic film alternately arranged, one organic film located at an interface directly contacting the emission elements and one inorganic film arranged firstly on the dummy bank portions when the sealing passivation layer extends from the display area to the non-display area.

According to other exemplary embodiments of the present invention, there is provided a flat panel display device including a display area where a desired image is displayed and a non-display area located at an outside of the display area. The flat panel display device includes bank portions arranged in a pattern in the display area and partitioning a plurality of openings, emission elements located in the openings, dummy bank portions formed in the non-display area and integrated with the bank portions in the display area, an encapsulation material burying the dummy bank portions, and a sealing passivation layer covering the emission elements and having a multi-layered structure of at least one organic film and at least one inorganic film alternately arranged.

According to other exemplary embodiments of the present invention, there is provided a flat panel display device including a display area where a desired image is displayed and a non-display area located at an outside of the display area. The flat panel display device includes bank portions arranged in a pattern in the display area and partitioning a plurality of openings, emission elements located in the openings, dummy bank portions formed in the non-display area and integrated with the bank portions, blocking members disposed between the dummy bank portions preventing permeation of harmful material to the emission elements, and a sealing passivation layer covering the emission elements and having a multi-layered structure of at least one organic film and at least one inorganic film alternately arranged.

According to other exemplary embodiments of the present invention, there is provided a flat panel display device including a display area where a desired image is displayed and a non-display area located at an outside of the display area. The flat panel display device includes bank portions arranged in a pattern in the display area and partitioning a plurality of openings, emission elements located in the openings, dummy bank portions formed in the non-display area and integrated with the bank portions in the display area, and a sealing passivation layer isolating the emission elements from outside air and having a multi-layered structure of at least one organic film and at least one inorganic film alternately arranged and extending from the display area to the non-display area.

According to other exemplary embodiments of the present invention, there is provided a method of fabricating a flat panel device having protection from harmful material, the flat panel display device including a display area where an image is displayed and a non-display area located at an outside of the display area, the method including providing a substrate, forming bank portions within the display area on the first substrate in a pattern having partitioned openings to receive emission elements within the openings, and forming dummy bank portions within the non-display area on the first substrate substantially simultaneously with forming the bank portions in the display area, the dummy bank portions forming at least part of a blocking wall preventing entrance of harmful material into the display area from a side of the flat panel device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2Ais a plan view of an exemplary flat panel display device according to an exemplary embodiment of the present invention, andFIG. 2Bis an enlarged view of portion A ofFIG. 2A. Referring toFIG. 2A, the flat panel display device includes a display area DP where a desired image is displayed, and a non-display area bordering the display area DP with a desired width W1. As shown inFIG. 2B, in the display area DP, a plurality of subpixels SP are arranged in an array and each subpixel SP is classified as a red subpixel (R), a green subpixel (G) or a blue subpixel (B) according to emission color. While a particular pattern of subpixels SP is shown, it should be understood that alternate patterns would be within the scope of these embodiments. For example, a first row of subpixels SP may have a different pattern than a second row of subpixels SP. A unit pixel consists of a red subpixel, a green subpixel, and a blue subpixel and each subpixel SP includes an emission element (referred to as an organic electroluminescent element or an “organic EL element”) having a corresponding emission color. The non-display area is located along the outside of the display area DP to provide a shielding function to the display area DP.

FIG. 3is a perspective view of the exemplary flat panel display device ofFIGS. 2A and 2B, according to an exemplary embodiment of the present invention, andFIG. 4is a cross-sectional view of the exemplary flat panel display device ofFIG. 2taken along line III-III indicated inFIG. 2A, according to an exemplary embodiment of the present invention. Referring toFIGS. 3 and 4, the display area DP is provided with bank portions131partitioning a plurality of organic EL elements120. Each organic EL element120forms an electrical and optical independent light-emitting area by the bank portions131.

Each organic EL element120includes a first electrode121and a second electrode127, and an organic film inserted between the first and second electrodes121and127. As shown inFIGS. 3 and 4, the organic film includes an emission layer123and a hole injecting layer125. If a low molecular organic film is used as the organic film, it may have a stacked structure of a hole injection layer (“HIL”), a hole transport layer (“HTL”), an emission layer (“EML”), an electron injection layer (“EIL”), and an electron transport layer (“ETL”), or a combination thereof. Also, if a high molecular organic film is used as the organic film, it may have a stacked structure of a hole transport layer (“HTL”) and an emission layer (“EML”). The organic film is not limited to the above-described structures, and may instead be, for example, a single emission layer or a two-layered structure of a hole transport layer and an emission layer or a two-layered structure of an emission layer and an electron transport layer.

The emission layer123for each organic EL element120is classified as a red emission layer, a green emission layer, or a blue emission layer according to emission color and the red, green, and blue emission layers are located side by side constructing one pixel.

The first electrode121and the second electrode127function as a cathode and an anode respectively and the first electrode121may be formed commonly for a plurality of the organic EL elements120and the second electrode127may be formed independently for each organic EL element120. The flat panel display device according to the current embodiment of the present invention is a top emission type device and it is desirable for light extraction effectiveness to form the second electrode127of a transparent electrode material. The transparent electrode material used to form the second electrode127is, for example, indium tin oxide (“ITO”), indium zinc oxide (“IZO”), etc. In the meantime, it is desirable to form the first electrode121as a metal film having good light reflection properties to reflect light incident to the first electrode121upwards and for example, a conducting material such as Al or Ag may be used to form the first electrode121.

The flat panel display device as shown is an active matrix display device including thin film transistors (“TFTs”), and TFTs such as switching TFTs, driving TFTs, etc. and capacitors may be included in a TFT layer115deposited under the organic light-emitting diode120. The number or the type of the TFTs is not limited to the above described TFTs and thus, it is possible to make various modifications. For example, a switching TFT detects an on/off condition of the corresponding organic EL element120and a driving TFT controls the current supplied to the organic EL element120according to a switching TFT signal. The second electrode127is connected electrically to the drain electrode of the driving TFT and a controlled driving current is supplied to the corresponding organic EL element120through the second electrode127.

In the non-display area, dummy bank portions135integrated with the bank portions131in display area DP are provided. The dummy bank portions135of the non-display area are formed together with the bank portions131of the display area DP. The bank portions131partition a plurality of openings120′ in a matrix pattern and the dummy bank portions135having a width W2are formed at the outside of the display area DP. The bank portions131and the dummy bank portions135integrated thereto are for example, formed using the following process. After coating a raw material used for forming the bank portions131on a first substrate111, on which a TFT layer115and a first electrode121are already formed, e.g., polymer resin material such as PVA over the whole surface of the substrate111including the display area DP and the non-display area, a uniform opening pattern is formed over the display area DP defining the emission area of the organic EL elements120. In this way, the bank portions131of the display area DP and the dummy bank portions135of the non-display area are concurrently obtained. That is, the bank portions131and the dummy bank portions135are formed within a same processing step of fabricating the flat panel display device. In the openings120′, the emission layer123, the organic film including the hole injection layer125, and the second electrode127are formed successively thereby obtaining the organic EL elements120.

The dummy bank portions135perform a shielding function preventing the permeation of harmful material, thereby preventing portions of the organic EL element120, such as the emission layer123or the first and second electrodes121and127, from being oxidised and corroded. As compared with conventional methods requiring an additional process and cost for manufacturing a partitioning wall to prevent the permeation of harmful material, the exemplary embodiments of the present invention use a conventional process for forming the bank portions131in the display area DP for the dummy bank portion135functioning as a shielding barrier so that additional processes or costs are minimized. The dummy bank portions135are designed to have a width W2to prevent the permeation of harmful material. The width W2of the dummy bank portions135may be designed to have twice the pitch (2×P) or more (W2>2×P) in a pixel array such that a unit pixel consisting of red, green, and blue subpixels is repeated by one pitch distance P (Refer toFIG. 2).

It is desirable that when the upper portion of the flat panel display device is covered by a second substrate150, the dummy bank portions135are higher than the bank portions131to sufficiently blocking out the outside air. That is, it is desirable to satisfy a relationship of h2) h1wherein the height of the bank portions131is h1and the height of the dummy bank portion135is h2.

In the present invention, in order to prevent the permeation of moisture and oxygen into the organic EL element120, a sealing passivation layer140is formed on the organic EL elements120, having a thickness t and a multi-layer structure of an organic film141and an inorganic film145. The sealing passivation layer140preferably has at least two films141and145to block the permeation of the harmful material. In this case, the sealing passivation layer140has at least one of the organic film141and at least one of the inorganic film145, and further has alternating layers of the organic film141and the inorganic film145.

The organic film141may be formed of a high molecular organic film, for example, polyacrylate, polyurea, polyester, polyethylene, polypropylene, methacrylic, acrylic etc. and derivatives thereof or a small molecular organic film but the present invention is not limited thereto. Also, the inorganic film145deposited on the organic film141may be formed of silicon oxide, silicon carbide or silicon nitride, for example SiO2, SiC, SiN, SiON or In2O3, TiO2, Al2O3.

Due to the multi-layered sealing passivation layer140, the permeation of harmful material through a main surface, i.e., a path R1indicated inFIG. 4is effectively prevented. However, in spite of the multi-layered sealing passivation layer140, harmful material permeating along a path R2, i.e., through the side portion of the sealing passivation layer140is not prevented effectively. In order to prevent harmful material permeating along a path R2, in exemplary embodiments of the present invention, the sealing passivation layer140has a multi-layered structure where a layer of the sealing passivation layer140directly contacting the organic EL elements120, i.e., an interface film directly contacting the organic EL elements120, should be an organic film141having a planarizing effect. Further, the order of depositing is determined such that the film arranged firstly on the dummy bank portion135is to be an inorganic film145when the multi-layered sealing passivation layer140extends from the display area DP to the non-display area. In this way, the permeation of oxygen/moisture through the side portion of the organic film141, which is relatively weak, is prevented. Thus, at least the organic film141forming the interface film directly contacting the organic EL elements120has a smaller peripheral area than the inorganic film145directly contacting the dummy bank portion135.

Referring toFIG. 3, the bank portions131are formed in a matrix pattern and the organic EL elements120partitioned by the bank portions131are arranged in parallel along a first direction and a second direction perpendicular to the first direction. The scope of the invention, however, is not limited to the pattern of the bank portions131shown inFIG. 3.FIGS. 5 and 6are perspective views of exemplary flat panel display devices according to other exemplary embodiments of the present invention. As shown inFIG. 5, the organic EL elements120partitioned by the bank portions131are arranged in parallel along a first direction but may be also arranged in a zigzag formation along a second direction perpendicular to the first direction. Referring toFIG. 6, organic EL elements120partitioned by bank portions131have various polygonal shapes in a honey comb structure. In the flat panel display devices shown inFIG. 5 and 6, like reference numerals denote like elements in the previous embodiment and thus detailed descriptions thereof are omitted.

FIG. 7is a perspective view of an exemplary flat panel display device according to another exemplary embodiment of the present invention andFIG. 8is a cross-sectional view of the exemplary flat panel display device ofFIG. 7according to an exemplary embodiment of the present invention. Like reference numerals inFIGS. 7 and 8denote like elements in the previous embodiments. Referring toFIGS. 7 and 8, a plurality of bank portions131are provided in a desired pattern, i.e., a matrix pattern in the display area DP and films123,125, and127forming organic EL elements120are deposited successively in a plurality of first openings120′ partitioned by the bank portions131. The organic EL elements120form optical and electrical independent emission areas by the bank portions131.

In an exemplary embodiment of the present invention, dummy bank portions135are provided by extending the same pattern as the bank portions131, for example, the matrix pattern over the outside of the display area DP and a plurality of second openings160′ are segmented by the dummy bank portions135. While the first openings120′ in the display area DP are provided for the organic EL elements120and define the emission area, the second openings160′ are provided for an encapsulation material layer160to prevent the permeation of harmful material as described below. The bank portions131and the dummy bank portions135integrated therewith may be formed using the following process. After a raw material paste is coated on a substrate111supporting the TFT layer115and the first electrode121thereon, a certain shaped opening pattern is formed in the display area DP and the non-display area by photolithography.

The dummy bank portions135with the encapsulation material layer160block the permeation of oxygen/moisture in order that the organic EL elements120are not oxidized or corroded. Thus, it is desirable that at least two dummy bank portions135overlap side by side to sufficiently prevent the permeation of harmful material. The encapsulation material layer160fills in the dummy bank portions135formed at the non-display area and the second openings160′ between the dummy bank portions135. It is preferred that the encapsulation material layer160be formed of an inorganic material or metal having relatively strong resistance to oxygen/moisture.

The total height h3of the encapsulation material layer160filling the openings160′ between the dummy bank portions135preferably exceeds the height h1of the bank portions131in the display area DP, i.e., a relationship of h3) h1is satisfied. In this way, when a second substrate150is located on the dummy bank portions135, there is no gap between the second substrate150and the encapsulation material160so a good seal to moisture and oxygen is provided.

In the meantime, a sealing passivation layer140is located on the organic EL elements120to prevent the permeation of moisture and oxygen. The sealing passivation layer140includes an organic film141and an inorganic film145deposited alternately and preferably includes at least two of the films141and145for preventing the permeation of moisture and oxygen. The sealing passivation layer140extends from the display area DP where the organic EL elements120are located, to the non-display area. Thus, it is desirable that at least the interface film directly contacting to the organic EL element120is the organic film141having a planarizing effect and the film located firstly on the outermost portion of the dummy bank portions135covered by the encapsulation material layer160is the inorganic film145when the multiple layered sealing passivation layer140extends from the display area DP to the non-display area. Thus, at least the organic film141forming the interface film directly contacting the organic EL elements120has a smaller peripheral area than the inorganic film145directly contacting the encapsulation material layer160over the dummy bank portions135.

FIGS. 9 and 10are respective perspective and cross sectional views of a flat panel display device according to another exemplary embodiment of the invention. Like reference numerals inFIGS. 9 and 10denote like elements in the previous embodiments. Referring to the figures, the bank portions131are formed in matrix pattern within the central display area DP and within each opening120′ partitioned by the bank portions131, the emission layer123, the hole injection layer125, and the second electrode127are deposited successively to form each organic EL element120. At the non-display area, and within a width W2, the dummy bank portions135are formed. In the exemplary embodiment, blocking members170are formed in the dummy bank portions135. The blocking members170may alternate with the dummy bank portions135. The blocking members170may be made of metal or inorganic material having a good blocking property to the outside air such as moisture/oxygen. For example, the dummy bank portions135into which the blocking members170are inserted may be made by the following manufacturing method. After the blocking members170are fixed temporarily on the non-display area on the substrate111upon which the TFT layer115and the first electrode121are deposited, a raw material paste is coated on the overall surface of the first substrate111. At this time, the blocking members170located on the first substrate111are enclosed by the paste ejected by a coating device and the blocking members170are fixed securely at their positions.

The height h4of the outer dummy bank portions135is preferably higher than the height h1of the inner bank portion131, i.e., a relationship of h4) h1is satisfied so that the organic EL element120is sealed by the second substrate150covering it. On the organic EL element120, the sealing passivation layer140is provided to prevent the permeation of harmful material. The sealing passivation layer140has a multi-layered structure including the organic film141and the inorganic film145having a different material property to each other and deposited alternately. The sealing passivation layer140preferably has at least two or more films141and145. The sealing passivation layer140extends from the display area DP to the outside non-display area. It is preferred that at least the interface film directly contacting the organic EL elements120is the organic film141and the film located firstly on the outermost portion of the dummy bank portions135and the blocking members170is the inorganic film145when the multiple layered sealing passivation layer140extends from the display area DP to the non-display area. Thus, at least the organic film141forming the interface film directly contacting the organic EL elements120has a smaller peripheral area than the inorganic film145directly contacting the dummy bank portions135and the blocking members170.

Thus, in each of the above-described exemplary embodiments, a blocking wall is provided on a non-display area of a display device for protecting the inner emission element of the display device from permeation of harmful material such as oxygen/moisture, where the blocking wall includes dummy bank portions formed from the same material used in forming bank portions in the display area of the display device, and formed within a same processing step as the bank portions in the display area of the display device. In exemplary embodiments of the present invention, the blocking wall may include only the dummy bank portions having an enlarged width, may include a same pattern as the bank portions in the display area and then filled with an encapsulation material layer, or many include blocking members alternately arranged with the dummy bank portions. However, it should be understood that the blocking wall may include alternate arrangements while still employing the dummy bank portions within the blocking wall.

For convenience of explanation, the active matrix flat panel display device controlling an input signal per pixel using TFTs has been described as an embodiment of the display device, but the substantial characteristic of the invention is not limited to the driving method. Thus, exemplary features of the present invention may be applied to the passive matrix flat panel display device using the same method as described above.

According to the exemplary flat panel display devices of the exemplary embodiments of the invention, in order to protect the inner emission element of the display device from permeation of harmful material such as oxygen/moisture, the inner portion of the display device is sealed in high sealing property so that degradation of performance such as production of dark spots creating a loss of display function and degradation of luminescence is prevented and the life of the product is prolonged.

Also, according to the exemplary embodiments and features of the invention, the sealing passivation layer is formed in a multiple layered structure and the order of depositing for sealing the passivation layer is limited as described above so that a more effective seal against harmful material is realized.

Further, according to the exemplary flat panel display devices of the exemplary embodiments of the invention, by using the conventional process forming the bank portions, the dummy banks are formed with a shielding function so that additional manufacturing processes or additional charge of manufacturing costs for blocking the permeation of harmful material may be minimized.