Method of manufacturing substrate and organic emitting display device having the substrate

Provided are an organic light emitting display device and a method of manufacturing the same. The organic light emitting display device includes a substrate; an sealing substrate facing the substrate, an organic light emitting unit disposed between the substrate and the sealing substrate and having a plurality of organic light emitting devices emitting light, and a plurality of grooves formed in a light extracting surface of the organic light emitting display device through which the light is emitted to the outside. In one embodiment, the grooves are formed on the sealing substrate, and in another embodiment, the grooves are formed on the substrate.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for METHOD OF MANUFACTURING SUBSTRATE AND ORGANIC EMITTING DISPLAY DEVICE HAVING THE SUBSTRATE earlier filed in the Korean Intellectual Property Office on the 24 Apr. 2008 and there duly assigned Serial No. 10-2008-0038251.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a substrate and an organic light emitting display device having the substrate, and particularly, to a method of manufacturing a substrate which improves the visibility due to reduced reflectivity of external light, and an organic light emitting device having the substrate.

2. Description of the Related Art

In general, flat panel displays (FPDs) are classified according to the material type into inorganic display devices and organic display devices. Examples of inorganic display devices include plasma display panels (PDPs) using photoluminescence (PL) and field emission displays (FEDs) using cathode luminescence (CE). Examples of organic display devices include liquid crystal displays (LCDs) and organic light emitting element devices.

An organic light emitting element device includes a first electrode and a second electrode facing each other, and a light emitting layer interposed between the first and second electrodes. Since the organic light emitting element device is easily damaged by water or oxygen from the outside, the organic electroluminescent display device is encapsulated in order to prevent penetration of impurities from the outside.

As the organic light emitting display devices, including the organic light emitting element devices, have higher response speed than the currently widely used LCDs, the organic display devices can realize mobile images and have a wide viewing angle and high brightness due to self-emission, and thus are considered to be the next-generation of display devices.

SUMMARY OF THE INVENTION

The present invention provides an organic light emitting display device having improved visibility by reducing the reflectivity of incident light, and a method of manufacturing the organic light emitting display device.

According to an aspect of the present invention, there is provided an organic light emitting display device comprising a substrate, an sealing substrate facing the substrate, an organic light emitting unit disposed between the substrate and the sealing substrate and including a plurality of organic light emitting devices for emitting light, and a plurality of grooves formed in a light extracting surface of the organic light emitting display device through which the light is emitted to the outside.

The light extracting surface may be one surface of the sealing substrate that is directed to the outside. The light extracting surface may be one surface of the substrate that is directed to the outside.

The grooves may be regularly arranged or irregularly arranged.

The grooves may be concave with respect to the light extracting surface.

The grooves may be formed in the form of concave lenses. The grooves may be formed in the form of spherical concave lenses. The grooves may be formed in the form of oval concave lenses. The grooves may be concavely formed in the form of slits. The grooves may be formed to overlap one another in a continuous arrangement.

One of the grooves may be spatially aligned with one of the organic light emitting devices. The size of the one of the grooves may be smaller than the size of the one of the organic light emitting devices.

A distance between two of the grooves may be greater than a distance between two of the organic light emitting devices.

According to another aspect of the present invention, there is provided a method of manufacturing a substrate, the method comprising providing a substrate, forming scratches in a surface of the substrate, and forming a plurality of grooves by spraying an etchant onto the surface of the substrate.

The scratches may be formed at regular distances from each other. The scratches may be formed at irregular distances from each other. The grooves may be concavely formed with respect to the surface of the substrate.

The step of forming the plurality of grooves may comprise etching the surface of the substrate by the etchant, and cleansing the surface of the substrate.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms, and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Thus, the shape and size of the elements in the drawings may be exaggerated for clarity, and like reference numerals denote like elements throughout the specification.

FIG. 1is a cross-sectional view of an organic light emitting display device100according to an embodiment of the present invention. Referring toFIG. 1, the organic light emitting display device100may include a sealing substrate101, a substrate102, an organic light emitting unit103, and grooves110.

The sealing substrate101may be disposed above the organic light emitting unit103and attached to the substrate102. As illustrated inFIG. 1, the sealing substrate101may be separated from the organic light emitting unit103and attached to the substrate102using a bonding member (not shown). The sealing substrate101may be a glass substrate or other various plastic substrates such as acryl. When the organic light emitting display device100is a top emission type organic light emitting device as illustrated inFIG. 1, the sealing substrate101may be formed of an electric insulating material having high transmittance with respect to light generated from the organic light emitting unit103. For example, the sealing substrate101may be formed of a transparent glass such as alkali glass or non-alkali glass, transparent ceramics such as polyethylene terephtahlate, polycarbonate, polyether sulfone, polyvinyl fluoride (PVF), poly acrylate, zirconia, etc., or quartz.

The organic light emitting unit103is formed on the substrate102. The substrate102may be formed of a material such as transparent glass, plastic sheet, or silicon, and may be either flexible or not flexible, and either transparent or not transparent. Also, the substrate102may be a metal substrate. When an organic light emitting display device200is a bottom emission type organic light emitting display device, a substrate202is formed of a transparent material.

The organic light emitting unit103may be formed on the substrate102. The organic light emitting unit103may include a plurality of organic light emitting devices (not shown). The organic light emitting device may include a first electrode layer, a second electrode layer facing the first electrode layer, and an intermediate layer interposed between the first and second electrode layers and including at least a light emitting layer. The first electrode layer may be a transparent electrode or a reflective electrode.

When the first electrode layer is formed of a transparent electrode, it may be formed of ITO, IZO, ZnO or In2O3; and when formed of a reflective electrode, the first electrode layer may be formed of a reflection layer formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound of these, and a layer formed of ITO, IZO, ZnO or In2O3, and formed on the reflection layer. The second electrode layer also may be formed of a transparent electrode or a reflective electrode. When formed of a transparent electrode, the second electrode layer may include a layer in which Li, Ca, LiF/Ca, LiF/Al, Al, Mg or a compound of these is deposited to direct to the intermediate layer between the first and second layers, and an auxiliary electrode or a bus electrode line formed of a material for forming a transparent electrode (e.g., ITO, IZO, ZnO or In2O3). When formed of a reflective electrode, the second electrode layer may be formed by depositing Li, Ca, LiF/Ca, LiF/Al, Al, Mg or a compound of these. The intermediate layer between the first and second electrodes may be formed of a small molecular organic material or a polymer organic material. When using a small molecular organic material, the intermediate layer may be formed to have a single or complex structure including a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), etc. Examples of the organic materials include copper phthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum)(Alq3), and so forth. The small molecular organic material may be formed using a vacuum deposition method using a mask. The polymer organic material may have a structure including an HTL and an EML; here, poly(3,4-ethylenedioxythiophene) (PEDOT) may be used as an HTL, and polymer organic materials such as poly-phenylenevinylene (PPV) based materials or polyfluorene based materials may be used as an EML.

A plurality of grooves110may be formed in a light extracting surface A of the organic light emitting display device100. As shown inFIG. 1, the light extracting surface A is a surface of the sealing substrate101directed to the outside in the top emission type organic light emitting display device100. Light generated in the organic light emitting unit103is emitted to the outside through the sealing substrate101, and thus a surface of the sealing substrate101may be the light extracting surface A.

The grooves110may be formed to be concave with respect to the light extracting surface A. In other words, the grooves110may be recessed inwardly from a surface of the sealing substrate101.FIGS. 2 through 4illustrate grooves111,112, and113formed in various shapes. Referring toFIG. 2, the grooves111may be formed concavely with respect to the surface of the sealing substrate101. The grooves111may have the form of concave lenses. In particular, the grooves111may have the form of spherical concave lenses or oval concave lenses. The grooves111may be separated from one another, and formed at regular or irregular distances from each other.

When the grooves111are formed at regular distances, the grooves111may be formed in a manner that one groove is spatially aligned with one of the organic light emitting devices included in the organic light emitting unit103. Thus, in this case, one groove corresponds only to one light emitting device, and a line connecting the center of the groove to the center of the light emitting device is perpendicular to the surface of the organic light emitting device. As described above, the organic light emitting device is formed of a first electrode layer, a light emitting layer, and a second electrode layer. When external light passes through the sealing substrate101and is incident on the organic light emitting devices, the light is reflected on the first electrode layer and is transmitted to the outside again. Accordingly, the visibility of the organic light emitting display may decrease. However, according to the present invention, the grooves are formed to respectively correspond to the organic light emitting devices, and thus external light that is incident on the organic light emitting devices is refracted in the grooves, and the amount of light that is incident on the first electrode layer of the organic light emitting device is reduced. Accordingly, according to the current embodiment of the present invention, the reflectivity of external light is reduced.

When the grooves111are formed to respectively correspond to the organic light emitting devices, the size of the grooves111, that is, the diameter thereof, may be smaller than the size of the organic light emitting devices. When the organic light emitting devices are rectangular, the size of the grooves111may be smaller than the width of the rectangular organic light emitting devices. For example, when the width of the organic light emitting devices is 60 μm, the size of the groove111may be smaller than 60 μm.

Also, the distances between the grooves111may be greater than the distances between the organic light emitting devices. For example, when the distance between the organic light emitting devices is 15 μm, the grooves111may be separated from one another at distances of 15 μm or greater. When the grooves111are formed to respectively correspond to the organic light emitting devices and to have a size greater than the distances between the organic light emitting devices, the size of the grooves111can be adjusted according to the distances therebetween.

As shown inFIG. 3, the grooves112may be formed to partly overlap one another. Also, as shown inFIG. 4, the grooves113may be formed to have a concave shape extending in one direction. In detail, the grooves113may be formed concavely in the form of slits. However, the shape of the grooves is not limited to the above examples, and the grooves may also be formed irregularly.

The grooves110,111,112, and113may be formed by scratching a surface of the sealing substrate101and spraying an etchant thereon. When the etchant is sprayed onto the surface of the sealing substrate101in which scratches are formed, the etchant soaks into the scratches, and thus portions of the sealing substrate101, in which the scratches are formed, are etched more deeply than portions, in which no scratch is formed, thereby obtaining concave patterns. A method of manufacturing these concave patterns will be described hereinafter.

As light generated in the organic light emitting unit103is transmitted through the light extracting surface A as described above, the user can watch images through the light extracting surface A. Also, as the light extracting surface A is directed to the outside, light is incident from the outside. Light incident from the outside is reflected on the light extracting surface A and may reduce the visibility of the organic light emitting display device100.

To prevent reflection of the external light incident on a light extracting surface, a polarization film has been used in the conventional art. However, a polarization film has low light transmittance and thus decreases the brightness of the organic light emitting device. In addition, the price of the polarization film is high, thus increasing the manufacturing cost.

According to the current embodiment of the present invention, a plurality of the grooves110are formed in the surface A of the sealing substrate101to reduce reflectivity of external light incident on the light extracting surface, thereby increasing the visibility of the organic light emitting display device. In detail, when light from the outside is incident on the light extracting surface A in which the concave grooves110,111,112, or113are formed, the external light is refracted internally inside the sealing substrate101due to the concave grooves110,111,112, or113, and can be diffused via total internal reflection inside the sealing substrate101. Accordingly, the reflectivity of the external light incident on the light extracting surface is reduced, and thus the visibility of the organic light emitting display device increases. Also, since the reflectivity of external light can be reduced, the sealing substrate having the grooves, instead of a polarization film, can be used to prevent the reflection. Thus, the manufacturing cost can be reduced. Also, since a plurality of grooves are formed in the sealing substrate101, when attaching other films onto the sealing substrate101, the surface area of the sealing substrate101is increased due to the grooves, and thus the adhesion of the sealing substrate101and other films can be improved.

FIG. 5is a cross-sectional view of an organic light emitting display device200according to another embodiment of the present invention. The organic light emitting display device ofFIG. 5is a bottom emission type organic light emitting display device. That is, light generated in the organic light emitting unit103may be emitted to the outside through a substrate202instead of a sealing substrate201. Accordingly, a light extracting surface B of the organic light emitting display device200is a surface of the substrate202directed to the outside. A plurality of grooves210may be formed in a surface B of the substrate202directed to the outside. As described above, the grooves210may be concave with respect to the light extracting surface B, and may be arranged as illustrated inFIGS. 2 through 4. Also, although not shown in the drawing, the grooves210may be formed irregularly.

Hereinafter, a method of manufacturing a substrate according to an embodiment of the present invention will be described, and processes thereof are illustrated inFIGS. 6 through 9.

First, as illustrated inFIGS. 6 and 7, a substrate301is provided, and then fine scratches302are formed in a surface of the substrate301. In order to form the scratches302in the surface of the substrate301, a cylindrical roller401including sharp protrusions401aon its outer circumference may be rolled along the surface of the substrate301as illustrated inFIG. 6. As the cylindrical roller401is rolled while applying a predetermined force toward the surface of the substrate301, scratches302may be formed in the surface of the substrate301. The arrangement of the scratches302formed on the surface of the substrate301may differ according to the arrangement of the protrusions401aformed on the outer circumference of the roller401. Since the protrusions401aof the roller401should be able to form scratches in the substrate301, the hardness of the protrusions401aof the roller401may preferably be greater than the hardness of the substrate301. For example, when the substrate301is formed of glass, the protrusions401aof the roller401have greater hardness than the glass.

The present invention is not limited to the use of the cylindrical roller401, and other means capable of forming scratches302in the surface of the substrate301may also be used. As illustrated inFIG. 7, by pressing a stamp402having protrusions402on a surface of the stamp301, scratches302may be formed on the surface of the substrate301.

Next, referring toFIG. 8, an etchant E is sprayed onto the surface of the substrate301to form a plurality of grooves310. In detail, an etchant E is sprayed onto a surface of the substrate301in which the scratches302are formed. The etchant E sprayed onto the surface of the substrate301etches the surface of the substrate301. When the surface of the substrate301is etched, the etching speed is uniform, and thus the concave grooves310may be formed in portions of the substrate301where the scratches302are formed with respect to portions where the scratches302are not formed. The size or depth of the grooves310can be adjusted by controlling the composition or density of the etchant E, the etching temperature, the spray speed, the etching time, etc.

Then, as illustrated inFIG. 9, after spraying the etchant E onto the substrate of the substrate301, the surface is cleansed using a cleansing solution C. That is, the cleansing solution C can remove the etchant E sprayed on the surface of the substrate301.

FIG. 10is a photographic image showing the groove310formed by etching. The groove310has a form of a concave lens.

FIG. 11illustrate a scratch302formed in the substrate301, andFIG. 12illustrates the grooves310formed after etching. The concave grooves310are formed around the scratches302after etching.

Hereinafter, a method of manufacturing an organic light emitting display device according to an embodiment of the present invention will be described.FIGS. 13 through 17illustrate processes of the method of manufacturing an organic light emitting display device.

Referring toFIG. 13, a sealing substrate401, in which a plurality of grooves410is formed, is provided. The grooves410may be formed in the same manner as illustrated inFIGS. 6through9.

Then, as illustrated inFIGS. 14 through 16, an organic light emitting unit450is formed on the substrate402. The organic light emitting unit450may be formed in the following manner.

First, as illustrated inFIG. 14, a buffer layer403is formed on a surface of the substrate402. Then, as illustrated inFIG. 15, a p-type or an n-type semiconductor layer404arranged in a predetermined pattern on the buffer layer403and a gate insulating layer405burying the semiconductor layer404are formed, and a gate electrode layer406corresponding to the semiconductor layer404and a first insulating layer407burying the gate electrode layer406are formed on the gate insulating layer405, and a thin film transistor layer formed of a drain electrode408and a source electrode409electrically connected to both ends of the semiconductor layer404via the first insulating layer407and the gate insulating layer405is formed.

Drain electrode408and the source electrode409penetrate the first insulation layer407and the gate insulation layer405and are electrically connected to opposite sides, respectively, of the semiconductor layer404. Meanwhile, a first auxiliary electrode411bis formed on a bottom surface of the first insulation layer407to face a second auxiliary electrode411a, which is formed on a top surface of the gate insulation layer405during the formation of the gate electrode406, thereby forming a capacitor411. The second auxiliary electrode411ais connected to the source electrode409. Meanwhile, as illustrated inFIG. 16, a second insulating layer407ais formed on the top surface of the first insulating layer407, and a first electrode layer412that is electrically connected to the drain electrode408is formed on the second insulating layer407a, and a third insulating layer422is formed on the second insulating layer407aso as to expose the first electrode layer412. An organic layer421is formed on the first electrode layer412by deposition or printing, and a second electrode layer422a, which is a cathode, is formed on the421and the third insulating layer422.

The method of forming the above-described organic light emitting unit450is not limited to the current embodiment and may be modified in various manners. That is, the method of forming the organic light emitting unit450may vary according to the structure of the organic light emitting unit450.

When the formation of the organic light emitting unit450on the substrate402is completed as described above, the sealing substrate401is disposed above the organic light emitting unit450as illustrated inFIG. 17. The surface of the sealing substrate401in which the grooves410are formed is directed to the outside, and the sealing substrate401and the substrate402are bonded so that the organic light emitting unit450is disposed between the sealing substrate401and the substrate402. The sealing substrate401and the substrate402may be bonded using a bonding member (not shown) disposed on the boundaries of the sealing substrate401and the substrate402.

FIGS. 18 through 20illustrate processes of a method of manufacturing an organic light emitting display device according to another embodiment of the present invention. Referring toFIG. 18, a substrate501, which has a plurality of grooves510on its surface, is provided. The method of forming grooves510is as described above.

Then, an organic light emitting unit550is formed on the other surface of the substrate501. That is, a plurality of grooves510are formed in one surface of the substrate501, and the organic light emitting unit550is formed on the other surface of the substrate501. This is a difference from the method of manufacturing the organic light emitting display device illustrated inFIGS. 13 through 17.

The organic light emitting unit550is manufactured in the same manner as the organic light emitting unit450illustrated inFIGS. 14 through 16, and thus description thereof will be omitted.

Next, a sealing substrate502having at least one even surface is provided.

Next, the substrate501and the sealing substrate502are bonded such that the organic light emitting unit550is disposed between the substrate501and the sealing substrate502. The substrate501and the sealing substrate502can be bonded using a bonding member (not shown) disposed on the boundaries of the substrate501and the sealing substrate502.

The organic light emitting display device manufactured according to the method illustrated inFIGS. 13 through 17is a top emission type organic light emitting display device, and the organic light emitting display device manufactured according to the method illustrated inFIGS. 18 through 20is a bottom emission type organic light emitting display device.