KR102418575B1 - Organic light emitting display device - Google Patents

Abstract

The present invention relates to an organic light emitting diode display capable of effectively blocking moisture or oxygen flowing in from the outside. It has a plurality of hygroscopic particles, and since the hygroscopic particles gradually increase in size from the first substrate to the second substrate, the present invention can effectively block moisture or oxygen flowing in from the outside without damaging the pixel array.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY DEVICE}

The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device capable of effectively blocking moisture or oxygen flowing in from the outside.

A video display device that implements various information on a screen is a key technology in the information and communication era, and is developing in the direction of thinner, lighter, portable and high-performance. Accordingly, as a flat panel display capable of reducing the weight and volume, which are disadvantages of a cathode ray tube (CRT), an organic light emitting display device that displays an image by controlling the amount of light emitted by the emission layer is in the spotlight. The organic light emitting diode display (OLED) is a self-luminous device, and has low power consumption, high response speed, high luminous efficiency, high luminance, and a wide viewing angle.

Organic materials and metal materials included in the organic light emitting diode display are easily oxidized by external factors such as moisture (H2O) or oxygen (O2). In particular, when moisture or oxygen permeates into the organic light emitting layer disposed between the anode and the cathode electrode, the organic light emitting layer deteriorates, resulting in a pixel shrinkage defect that turns black from the edge of each sub-pixel. In addition, if the pixel shrinkage defect persists for a long time, a dark spot defect in which the entire area of the sub-pixel is discolored black, and thus reliability is deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic light emitting diode display capable of effectively blocking moisture or oxygen flowing in from the outside.

In order to achieve the above object, an organic light emitting diode display according to the present invention includes an adhesive layer disposed between a first and a second substrate, and the adhesive layer includes a plurality of hygroscopic particles having different sizes, the hygroscopic particles comprising: Since the size gradually increases from the first substrate to the second substrate, the present invention can effectively block moisture or oxygen flowing in from the outside without damaging the pixel array.

The present invention provides an adhesive layer comprising a plurality of hygroscopic particles having different sizes. In this case, since the hygroscopic particles having a smaller size than the larger hygroscopic particles are disposed closer to the pixel array, it is possible to prevent a defect in engraving on the pixel array due to the hygroscopic particles when the first and second substrates are adhered. In addition, in the present invention, since the hygroscopic particles having a larger size than the hygroscopic particles having a smaller size are disposed closer to the second substrate, the hygroscopic particles having a large size first adsorb or remove moisture or moisture from the outside, and then have a small size hygroscopicity Particles adsorb or remove moisture or moisture secondary. Accordingly, the organic light emitting diode display according to the present invention can effectively block moisture or oxygen flowing in from the outside.

1 is a cross-sectional view illustrating an organic light emitting diode display according to a first exemplary embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating sub-pixels constituting the pixel array shown in FIG. 1 .
3 is a cross-sectional view illustrating the driving transistor and the light emitting device shown in FIG. 2 .
4A to 4C are cross-sectional views illustrating a method of manufacturing the organic light emitting diode display illustrated in FIG. 1 .
5 is a cross-sectional view illustrating an organic light emitting diode display according to a second exemplary embodiment.
6A to 6C are cross-sectional views illustrating a method of manufacturing the organic light emitting diode display illustrated in FIG. 5 .

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view illustrating an organic light emitting display device according to the present invention.

The organic light emitting diode display shown in FIG. 1 includes first and second substrates 101 and 110 , a pixel array 150 disposed on the first substrate 101 , an encapsulation protective layer 118 , and an adhesive layer 140 . be prepared

The first substrate 101 is formed of a glass or plastic substrate. In the case of a plastic substrate, a polyimide-based or polycarbonate-based material may be used to have flexibility.

The second substrate 110 is disposed to face the first substrate 101 . A rear surface of the second substrate 110 is bonded to the adhesive layer 140 . The second substrate 110 is formed of a material such as glass, polymer, or metal according to the emission direction of the organic light emitting diode display 100 . For example, when the organic light emitting diode display is a bottom emission type, the second substrate 110 is formed of a material such as an opaque metal, and when the organic light emitting display is a top emission type, the second substrate 110 is transparent glass. It is made of a material such as

The pixel array 150 disposed on the first substrate 101 includes a plurality of sub-pixels. Each of the sub-pixels includes a pixel driving circuit and a light emitting device 130 connected to the pixel driving circuit as shown in FIG. 2 .

The pixel driving circuit includes a switching transistor T1 , a driving transistor T2 , and a storage capacitor Cst.

The switching transistor T1 is turned on when a scan pulse is supplied to the scan line SL and supplies the data signal supplied to the data line DL to the storage capacitor Cst and the gate electrode of the driving transistor T2 .

The storage capacitor Cst charges the difference voltage between the gate electrode and the source electrode of the driving transistor T2 and supplies it as the driving voltage of the driving transistor T2 .

The driving transistor T2 controls the current I supplied from the high voltage (VDD) supply line to the light emitting device 130 in response to a data signal supplied to the gate electrode of the driving transistor T2 to control the light emitting device 130 . to control the amount of light emitted by In addition, even when the switching transistor T1 is turned off, the driving transistor T2 supplies a constant current I until the data signal of the next frame is supplied by the voltage charged in the storage capacitor Cst to supply the light emitting device ( 130) to maintain luminescence.

As shown in FIG. 3 , the driving transistor T2 includes a gate electrode 156 , a source electrode 158 , a drain electrode 160 , and an active layer 154 .

The gate electrode 156 is formed on the gate insulating layer 112 disposed to cover the active layer 154 . The gate electrode 156 overlaps the channel region of the active layer 154 with the gate insulating layer 112 interposed therebetween. The gate electrode 156 may include any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or It may be a single layer or multiple layers made of an alloy thereof, but is not limited thereto.

The source electrode 158 is connected to a source region of the active layer 154 through a source contact hole 164S passing through the gate insulating layer 112 and the interlayer insulating layer 116 .

The drain electrode 160 is connected to the drain region of the active layer 154 through a drain contact hole 164D passing through the gate insulating layer 112 and the interlayer insulating layer 116 . In addition, the drain electrode 160 of the driving transistor T2 is exposed through the pixel contact hole 120 formed to penetrate the planarization layer 128 to be connected to the anode electrode 132 of the light emitting device 130 .

The source electrode 158 and the drain electrode 160 may include, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium (Nd). ) and copper (Cu), or may be a single layer or multiple layers made of an alloy thereof, but is not limited thereto.

The active layer 154 forms a channel region between the source electrode 158 and the drain electrode 160 . The active layer 154 is formed on the first substrate 101 to be disposed below the gate electrode 156 . The active layer 154 is formed of at least one of an amorphous semiconductor material, a polycrystalline semiconductor material, and an oxide semiconductor material.

A buffer layer 102 and a light blocking layer (not shown) may be disposed between the active layer 154 and the first substrate 101 . The light blocking layer is formed on the first substrate 101 to overlap the active layer 154 . The light blocking layer absorbs or reflects light incident from the outside, and thus blocks external light incident to the active layer 154 . The buffer film is formed in a single-layer or multi-layer structure of silicon oxide or silicon nitride on a substrate 101 made of glass or a plastic resin such as polyimide (PI). The buffer layer 102 prevents diffusion of moisture or impurities generated in the substrate 101 or controls a heat transfer rate during crystallization, so that the active layer 154 can be well crystallized.

The light emitting device 130 includes an anode electrode 132 connected to the drain electrode 160 of the driving transistor T2 , at least one organic light emitting layer 134 formed on the anode electrode 132 , and a low voltage (VSS). A cathode electrode 136 formed over the organic light emitting layer 134 to be connected to the supply line is provided. Here, the low voltage (VSS) supply line supplies a low voltage (VSS) lower than the high voltage (VDD) supplied through the high voltage (VDD) supply line.

The anode electrode 132 is in contact with the drain electrode 160 exposed through the pixel contact hole 120 penetrating the planarization layer 128 . The anode electrode 132 is disposed on the planarization layer 128 to be exposed in the light emitting region provided by the bank 138 . When applied to a bottom emission type organic light emitting display device, the anode electrode 132 is made of a transparent conductive layer such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO).

The cathode electrode 136 is formed on top and side surfaces of the organic light emitting layer 134 and the bank 138 to face the anode 132 with the organic light emitting layer 134 interposed therebetween. When applied to a bottom emission type organic light emitting display device, the cathode electrode 136 has a multi-layered structure including a transparent conductive layer and an opaque conductive layer having high reflective efficiency. The transparent conductive film is made of a material having a relatively large work function value, such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and the opaque conductive film is made of Al, Ag, Cu, Pb, Mo, It consists of a single-layer or multi-layer structure containing Ti or an alloy thereof. For example, the cathode electrode 136 is formed in a structure in which a transparent conductive film, an opaque conductive film, and a transparent conductive film are sequentially stacked.

The organic light emitting layer 134 is formed on the anode electrode 132 of the light emitting region provided by the bank 138 . A hole-related layer including a hole injection layer and a hole transport layer is disposed between the organic emission layer 134 and the anode electrode 132 , and an electron injection layer and an electron transport layer are disposed between the organic emission layer 134 and the cathode electrode 136 . An electron-related layer is disposed.

The encapsulation protective layer 118 is formed on the first substrate 101 to cover the pixel array 150 including the light emitting device 130 to protect the pixel array 150 from external moisture or oxygen. The encapsulation protective layer 118 is formed of an inorganic film or a structure in which inorganic or organic films are alternately stacked. The inorganic layer of the encapsulation protective layer 118 is formed of an inorganic insulating material capable of low-temperature deposition, such as silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiON), or aluminum oxide (Al2O3). The organic layer of the encapsulation protective layer 118 is formed of an organic insulating material such as acrylic resin, epoxy resin, polyimide, polyethylene, or silicon oxycarbon (SiOC).

The adhesive layer 140 is disposed between the first substrate 101 on which the pixel array 118 is formed and the second substrate 110 to adhere them. The adhesive layer 140 has a multi-layer structure having hygroscopic particles of different sizes for each layer. For example, in the present invention, as shown in FIG. 1 , a structure in which two types of hygroscopic particles 142b and 144b having different sizes are disposed in the adhesive layer 140 will be described as an example.

The adhesive layer 140 shown in FIG. 1 includes first and second adhesive layers 142 and 144 sequentially stacked on the pixel array 150 .

The first adhesive layer 142 is bonded to the first substrate 101 on which the encapsulation protection layer 118 disposed to cover the pixel array 150 is formed. The first adhesive layer 142 includes a first curable resin 142a and first hygroscopic particles 142b of a first size.

The second adhesive layer 144 is disposed on the first adhesive layer 142 to be bonded to the lower surface of the second substrate 110 . The second adhesive layer 144 includes a second curable resin 144a and second hygroscopic particles 144b having a second size larger than that of the first hygroscopic particles 142b.

The first and second hygroscopic particles 142b and 144b react with moisture, moisture, or oxygen flowing into the adhesive layer 140 to adsorb or remove moisture, moisture, or oxygen.

The first and second curable resins 142a and 144a may be formed of a photocurable or thermosetting resin, and the first and second curable resins 142a and 144a may be formed of the same material or different materials. .

Each of the first and second hygroscopic particles 142b and 144b is a desiccant containing silica containing hollow silica, zeolite, titania, zirconia or montmorillonite as a component, a metal salt, a metal oxide, etc. alone or by mixing two or more types can be used

Here, the metal oxide is a metal oxide such as lithium oxide (Li2O), sodium oxide (Na2O), barium oxide (BaO), calcium oxide (CaO), or magnesium oxide (MgO), an organic metal oxide or phosphorus pentoxide (P2O5), etc. may be used alone or in two or more types.

In addition, metal salts include lithium sulfate (Li2SO4), sodium sulfate (Na2SO4), calcium sulfate (CaSO4), magnesium sulfate (MgSO4), cobalt sulfate (CoSO4), gallium sulfate (Ga2(SO4)3), titanium sulfate (Ti(SO4) 2) or sulfates such as nickel sulfate (NiSO4), calcium chloride (CaCl2), magnesium chloride (MgCl2), strontium chloride (SrCl2), yttrium chloride (YCl3), copper chloride (CuCl2), cesium fluoride (CsF), tantalum fluoride ( TaF5), niobium fluoride (NbF5), lithium bromide (LiBr), calcium bromide (CaBr2), cesium bromide (CeBr3), selenium bromide (SeBr4), vanadium bromide (VBr3), magnesium bromide (MgBr2), barium iodide (BaI2) Alternatively, a metal halide such as magnesium iodide (MgI2) or a metal chlorate such as barium perchlorate (Ba(ClO4)2) or magnesium perchlorate (Mg(ClO4)2) may be used alone or in two or more types. On the other hand, the first and second hygroscopic particles are not limited to the above-described exemplary material.

The first and second hygroscopic particles 142b and 144b are formed using the same material to have different sizes, or are formed using materials having different sizes. At this time, each of the first and second hygroscopic particles 142b and 144b is formed in a nano size.

The first hygroscopic particles 142b having a smaller size than the second hygroscopic particles 144b are included in the first adhesive layer 142 close to the pixel array 150, and have a second hygroscopicity larger than the first hygroscopic particles 142b. Particles 144b are contained within the second adhesive layer 144 remote from the pixel array 150 .

On the other hand, when the second hygroscopic particles 144b having a large size are disposed close to the pixel array 150 , when the first substrate 101 on which the pixel array 150 is formed and the second substrate 110 are bonded to each other, the second Imprinting defects may occur in the pixel array 150 due to the hygroscopic particles 142b. To prevent this, in the present invention, the first hygroscopic particles 142b having a smaller size than the second hygroscopic particles 144b having a larger size are disposed closer to the pixel array 150 . Therefore, in the present invention, when the first substrate 101 and the second substrate 110 are adhered, it is possible to prevent a defect in the pixel array 150 from being engraved by the first and second hygroscopic particles 142b and 144b. can

In addition, since the first hygroscopic particles 142b are smaller in size than the second hygroscopic particles 144b, the curable resin 142a occupies the specific gravity of the first hygroscopic particles 142b in the first adhesive layer 142 . this is high Accordingly, the first adhesive layer 142 made of the first hygroscopic particles 142b and the curable resin 142a is applied when the first substrate 101 on which the pixel array 150 is formed and the second substrate 110 are bonded. As the pressure is buffered, it is possible to prevent the pixel array 150 disposed under the first adhesive layer 142 from being damaged.

Since the second hygroscopic particles 144b are larger in size than the first hygroscopic particles 142b, the specific gravity of the second hygroscopic particles 144b in the second adhesive layer 144 is the first in the first adhesive layer 142. It is higher than the specific gravity occupied by the hygroscopic particles (142b). In this case, the second adhesive layer 144 including the second hygroscopic particles 144b may adsorb or remove a larger amount of moisture or moisture than the first adhesive layer 142 including the first hygroscopic particles 142b. , the second adhesive layer 144 is disposed outside the first adhesive layer 142 . Moisture passing through the second adhesive layer 144 in the first adhesive layer 142 after first adsorbing or removing moisture or moisture from the outside in the second adhesive layer 144 disposed outside the first adhesive layer 142 Alternatively, moisture is adsorbed or removed secondarily. Accordingly, the organic light emitting diode display according to the present invention can effectively block moisture or oxygen flowing in from the outside.

A method of encapsulating an organic light emitting diode display having the first and second adhesive layers 142 and 144 will be described as follows, and the manufacturing method thereof is not limited to the following examples.

As a first embodiment of the encapsulation method, as shown in FIG. 4A on the substrate 101 on which the pixel array 150 and the encapsulation protective layer 118 are formed, the first curable resin 142a and the first hygroscopic particles 142b ) of the first adhesive layer 142 is transferred. Then, as shown in FIG. 4B , the second adhesive layer 144 made of the second curable resin 144a and the second hygroscopic particles 144b is transferred onto the first adhesive layer 142 . Then, the encapsulation substrate 110 is heated and compressed on the first substrate 101 to which the second adhesive layer 144 has been transferred.

As a second embodiment of the encapsulation method, a second adhesive layer 144 made of a second curable resin 144a and second hygroscopic particles 144b on the second substrate 110, and a first curable resin 142a and the first adhesive layer 142 made of the first hygroscopic particles 142b is sequentially transferred. Then, the second substrate 110 to which the first and second adhesive layers 142 and 144 are transferred is heated and compressed on the first substrate 101 on which the pixel array 150 and the encapsulation protective layer 118 are formed.

As a third embodiment of the encapsulation method, the first curable resin 142a and the first hygroscopic particles 142b are formed on the first substrate 101 on which the pixel array 150 and the encapsulation protective layer 118 are formed. The adhesive layer 142 is transferred. Then, the second adhesive layer 144 made of the second curable resin 144a and the second hygroscopic particles 144b is transferred onto the second substrate 110 . Then, the second substrate 110 to which the second adhesive layer 144 is transferred is heated and compressed on the first substrate 101 to which the first adhesive layer 142 has been transferred.

Meanwhile, in the present invention, the adhesive layer 140 has been described as an example of a multilayer structure including the first and second adhesive layers 142 and 144, but in addition, the adhesive layer 140 has different sizes of hygroscopic particles ( 142b, 144b) may be formed in a single-layer structure.

That is, the adhesive layer 140 shown in FIG. 5 includes one curable resin 141 and first and second hygroscopic particles 142b and 144b having different sizes. In this case, the size of the hygroscopic particles 142b and 144b is gradually increased from the first substrate 101 to the second substrate 110 . Accordingly, the first hygroscopic particles 142b having a small size are disposed close to the pixel array 150 , and the second hygroscopic particles 144b having a large size are disposed close to the second substrate 110 .

As described above, since the adhesive layer 140 shown in FIG. 5 includes one curable resin 141 , an interface does not exist inside the adhesive layer 140 . Due to the non-existence of the interface inside the adhesive layer 140 , it is possible to prevent peeling or tearing between the adhesive layers from occurring. Accordingly, the organic light emitting diode display shown in FIG. 5 may improve yield and reliability.

The encapsulation method of the organic light emitting diode display shown in FIG. 5 will be described with reference to FIGS. 6A to 6C .

As shown in FIG. 6A , the adhesive layer 140 is formed by mixing and coating the first and second hygroscopic particles 142b and 144b and the curable resin 141 on the first release film 113 . At this time, since the size of the second hygroscopic particles 144b is greater than that of the first hygroscopic particles 142b, the first and second hygroscopic particles 142b and 144b are the first hygroscopic particles 142b by their own weight. 2 It is disposed closer to the first release film 113 than the hygroscopic particles 144b. After the adhesive layer 140 is photocured or thermally cured, the second release film 115 is attached on the adhesive layer 140 .

Then, as shown in FIG. 6B, after removing the second release film 115, the adhesive layer 140 is applied to the first substrate ( 101) is transferred to the image. In this case, in the adhesive layer 140 , the first hygroscopic particles 142b are disposed close to the pixel array 150 and the second hygroscopic particles 144b are disposed far from the pixel array 150 .

Then, after removing the first release film 113 on the adhesive layer 140 , the second substrate 110 is heated and compressed on the first substrate 101 on which the adhesive layer 140 is formed.

Meanwhile, in the present invention, the structure of the adhesive layer 14 having first and second hygroscopic particles 142b and 144b having different sizes has been described as an example, but in addition, three or more types of hygroscopic particles having different sizes are included in the adhesive layer 140 . can be placed. In this case, the hygroscopic particles having a small size are disposed close to the pixel array 150 , and the hygroscopic particles having a large size are disposed close to the second substrate 110 . Accordingly, in the present invention, since the size of the hygroscopic particles is gradually increased from the first substrate 101 to the second substrate 110 , moisture or oxygen flowing in from the outside can be effectively blocked without damaging the pixel array 150 . .

The above description is merely illustrative of the present invention, and various modifications may be made by those of ordinary skill in the art to which the present invention pertains without departing from the technical spirit of the present invention. Therefore, the embodiments disclosed in the specification of the present invention do not limit the present invention. The scope of the present invention should be construed by the following claims, and all technologies within the scope equivalent thereto should be construed as being included in the scope of the present invention.

101,110: substrate 130: light emitting element
140: adhesive layer 141, 142a, 144a: curable resin
142b, 144b: hygroscopic particles 150: pixel array

Claims (7)

first and second substrates facing each other with a pixel array including a light emitting element therebetween;
It is disposed between the first and second substrates and includes a curable resin, and an adhesive layer including a plurality of first hygroscopic particles of a first size and second hygroscopic particles of a second size larger than the first size, respectively,
the first hygroscopic particles in the adhesive layer are arranged adjacent to the pixel array and the first substrate outside the pixel array,
wherein the second hygroscopic particles are further away from the pixel array than the first hygroscopic particles and are arranged adjacent to the second substrate;
Does not have an internal interface between the first hygroscopic particles and the second hygroscopic particles in the adhesive layer,
The first and second sizes of the organic light emitting diode display are nano-sized.
delete delete The method of claim 1,
In the adhesive layer, the first hygroscopic particles and the second hygroscopic particles are positioned at different vertical distances between the pixel array and the second substrate in the curable resin. delete The method of claim 1,
An organic light emitting diode display having a higher specific gravity of the second hygroscopic particles than a specific gravity of the first hygroscopic particles in the curable resin. The method for manufacturing the organic light emitting display device according to any one of claims 1 to 6, comprising:
The provision of the adhesive layer is
mixing and coating the first and second hygroscopic particles and the curable resin on a first release film;
arranging the second hygroscopic particles on the lower side by their own weight, and the first hygroscopic particles on the upper side than the second hygroscopic particles;
curing the curable resin to form an adhesive layer by fixing the first and second hygroscopic particles in the curable resin;
attaching a second release film on the adhesive layer; and
and inverting the adhesive layer to remove the second release film and attaching a surface of the adhesive layer that has been in contact with the second release film to the pixel array.

Images