KR100742377B1 - Organic light emitting display device and manufacturing method - Google Patents

Abstract

The present invention includes a substrate having a device, a lower electrode formed on the substrate, an organic film including at least an organic light emitting layer formed on the lower electrode, and an upper electrode disposed on the organic film and having a light extraction unit. An organic light emitting display device and a method of manufacturing the same are provided.

Light extraction part, reflective electrode, front light emission, mirror function

Description

Organic electroluminescent display device and manufacturing method therefor {Organic electro luminescence device and fabricating method of the same}

1 is a plan view of a unit pixel of an organic light emitting display device according to an exemplary embodiment of the present invention.

2A through 2H are cross-sectional views sequentially illustrating a process of manufacturing an organic light emitting display device according to an embodiment of the present invention.

3A and 3B are cross-sectional views when a thickness of a light extraction unit is 0 占 in an organic light emitting display device according to an embodiment of the present invention.

4 is a cross-sectional view of an organic light emitting display device according to another embodiment of the present invention.

           <Explanation of symbols for the main parts of the drawings>

1. Scan Line 2. Data Line

3. Common Power Line 5. Switching Thin Film Transistor

6. Driving thin film transistor 7. Capacitor

8. Lower electrode 9. Pixel part

200, 400. Substrate 210, 410. Buffer layer

220, 420. Gate insulating films 230, 430. Semiconductor layer

232, 432. Source area 234, 434. Channel area

236, 436. Drain regions 238, 438. Gate electrodes

240, 440. Interlayer insulating film 250, 450. Flattening film

252, 452. Source electrode 254, 454. Drain electrode

256, 258, 458. Contact holes 265, 465. Via holes

270, 470. First reflective film 500. Second reflective film

272, 472. Lower electrodes 280, 480. Pixel defining layer pattern

290, 490. Organic films 300, 500, 505. Upper electrode

302. Passivation films I and II. Light extraction

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, to a top emitting organic light emitting display device having a mirror function and a method of manufacturing the same, by forming an upper electrode as a reflective electrode including a light extraction unit.

In general, an organic light emitting display device injects electrons and holes from an electron injection electrode and a hole injection electrode into an emission layer, respectively, A light emitting display device that emits light when an exciton in which electrons and holes are combined falls from an excited state to a ground state.

In general, an organic light emitting display device has a substrate and a lower electrode on the substrate, an organic layer including an emission layer (EML) on the lower electrode, and an upper electrode on the organic layer. The organic layer may include a hole injection layer (HIL) and a hole transport layer (HTL) between the lower electrode and the light emitting layer, and an electron transfer layer (ETL) and an electron injection layer between the light emitting layer (EML) and the upper electrode. It may further include an injection layer (EIL).

Due to this principle, unlike the conventional liquid crystal thin film display device, since a separate light source is not required, the volume and weight of the device can be reduced.

The method of driving the organic light emitting display device may be classified into a passive matrix type and an active matrix type.

The passive matrix type organic light emitting display device has a simple structure and a simple manufacturing method. However, the passive matrix type organic light emitting display device has a high power consumption and a large area of the display device, and the opening ratio decreases as the number of wires increases.

Therefore, the passive matrix type organic light emitting display device is used for a small display device, while the active matrix type organic light emitting display device is used for a large area display device.

In addition, the organic light emitting display device may be divided into a bottom light emitting structure and a top light emitting structure according to the direction in which light generated from the organic light emitting layer is emitted. The back light emitting structure reflects the upper electrode as light is emitted toward the substrate on which the device is formed. The electrode is formed and the lower electrode is formed as a transparent electrode. Here, when the organic light emitting display device adopts an active matrix method in which a thin film transistor is formed, a portion where the thin film transistor is formed may not transmit light, thereby reducing the area where light can be emitted. In contrast, in the front light emitting structure, the light is emitted in a direction opposite to the substrate by forming the upper electrode as a semi-transmissive metal electrode and the lower electrode as a transparent electrode including a reflective film. Widens

In general, the front-emitting organic light emitting display device uses the resonance effect of light, so it is important to form the thickness of the upper electrode in the wavelength range as much as possible, and the thickness of the hole injection layer and the hole transport layer provided between the emission layer and the upper electrode in the wavelength band. Forming consistently is also important. The hole injection layer facilitates injection of holes from the lower electrode as the anode. The hole transport layer easily transports holes, binds electrons to a light emitting region, increases the probability of forming excitons, and has high hole mobility.

However, in the case of the front-emitting organic light emitting display device for high resolution, the viewing angle is a problem when viewed from the side due to the resonance effect due to the application of the transflective cathode. In addition, the front-emitting organic light emitting device has a problem in implementing a reflective mirror function due to the structure different from the LCD basically.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and by forming a light extracting portion in a predetermined area in the center of the pixel portion of the organic light emitting display device and forming a cathode electrode outside the light extracting portion, the front light emitting organic light emitting display The problem of viewing angles in display devices can be solved, and voltage drop (IR DROP) caused by thin transflective cathode electrodes and the lifespan of display devices can be improved.

In addition, an object of the present invention is to implement a front-emitting organic light emitting display device that can be used as a mirror when the power supply is turned off, thereby improving the merchandise and convenience of the user.

In order to achieve the above object, the top-emitting organic light emitting display device according to the present invention,

A substrate having an element;

A lower electrode formed on the substrate;

An organic layer including at least an organic emission layer formed on the lower electrode; And

And an upper electrode disposed on the organic layer and having a light extraction unit.

The thickness of the upper electrode is formed to 800 Å to 3000 Å,

The thickness of the upper electrode in the light extraction portion is formed to be less than 800Å,

When the thickness of the upper electrode in the light extraction unit is 0Å and further comprising a passivation film on top of the organic film and the upper electrode,

The light extraction portion of the upper electrode is characterized in that the diameter from the center of the pixel portion is formed from 3/10 to 2/5 of the entire pixel portion.

In addition, the top-emitting organic light emitting display device according to the present invention,

A substrate having an element;

A lower electrode formed on the substrate;

An organic layer formed on the lower electrode and including at least an organic emission layer; And

And an upper electrode disposed on the organic layer, the upper electrode including a light extraction unit and a reflective film in a region other than the light extraction unit.

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In order to achieve the above object, a method of manufacturing a top-emitting organic light emitting display device according to the present invention,

Providing a substrate having an element;

Forming a lower electrode on the substrate;

Forming an organic layer including at least an organic emission layer on the lower electrode;

And an upper electrode disposed on the organic layer, the upper electrode having a light extracting unit, and a manufacturing method of the organic light emitting display device comprising:

The thickness of the upper electrode is formed to 800 ~ 3000Å,

The thickness of the upper electrode in the light extraction portion is formed to 800Å or less,

When the thickness of the upper electrode in the light extraction unit is 0Å and further comprising a passivation film on top of the organic film and the upper electrode,

The light extraction portion of the upper electrode is characterized in that the diameter from the center of the pixel portion is formed from 3/10 to 2/5 of the entire pixel portion.

In addition, in order to achieve the above object, a method of manufacturing a top-emitting organic light emitting display device according to the present invention,

Providing a substrate having an element;

Forming a lower electrode on the substrate;

Forming an organic layer including at least an organic emission layer on the lower electrode;

And an upper electrode disposed on the organic layer, the upper electrode including a light extracting unit, and including a reflecting layer, wherein the organic light emitting display device comprises:

The light extraction portion is characterized in that the opening.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

(Example 1)

Although the present invention describes an active matrix method as an embodiment, the present invention is not necessarily limited thereto and may be applied to a passive matrix method.

1 is a plan view of a unit pixel of an organic light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a scan line 1 arranged in one direction, a data line 2 intersecting while insulated from the scan line 1, and an intersecting line and insulated from the scan line 1, the data line ( The common power supply line 3 is located parallel to 2). The scan line 1, the data line 2, and the common power supply line 3 represent one of a plurality of unit pixels, for example, one of red (R), green (G), and blue (B). It is defined as a unit pixel.

Accordingly, the unit pixel includes a data signal applied to the data line 2 according to a signal applied to the scan line 1, for example, a data voltage and a voltage difference applied to the common power supply line 3. The capacitor 7 which accumulates the charge and the signal generated by the charge accumulated in the capacitor 7 are input to the driving thin film transistor 6 through the switching thin film transistor 5. Subsequently, the driving thin film transistor 6 receiving the data signal sends an electrical signal to the pixel portion 9 having the organic layer between the lower electrode 8, the upper electrode, and the two electrodes to emit light.

2A through 2H are cross-sectional views sequentially illustrating a process of manufacturing an organic light emitting display device according to an exemplary embodiment of the present invention. FIG. 2A through 2H are cross-sectional views taken along the line AA of FIG. 1.

Referring to FIG. 2A, the organic light emitting display device according to the present invention selectively forms a buffer layer 210 to a predetermined thickness on a substrate 200 made of glass, synthetic resin, stainless steel, or the like. In this case, the buffer layer 210 prevents the diffusion of impurities in the substrate 200 during the crystallization process of amorphous silicon formed in a subsequent process.

Next, as shown in FIG. 2B, after depositing amorphous silicon (not shown) on the buffer layer 210 to a predetermined thickness, the amorphous silicon layer is crystallized and patterned by a photolithography process to form a semiconductor layer ( 230 is formed, and a gate insulating film 220 is deposited on the entire surface of the substrate 200. In this case, the gate insulating film 220 may be formed using a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN _x ), or a stacked structure thereof.

Subsequently, a single layer of an aluminum alloy, such as aluminum (Al) or aluminum-neodymium (Al-Nd), or a plurality of aluminum alloys stacked on a chromium (Cr) or molybdenum (Mo) alloy on the gate insulating layer 220. The gate electrode metal layer (not shown) is formed as a layer, and the gate electrode metal layer is etched by a photolithography process to form the gate electrode 238 at a predetermined portion corresponding to the semiconductor layer 230. Subsequently, the source region 232 and the drain region 236 are formed using the gate electrode 238 as a mask by doping a conductive impurity. An impurity doped region between the source region 232 and the drain region 236 serves as the channel region 234. However, the doping process may be performed by forming a photoresist before forming the gate electrode 238.

Next, as shown in FIG. 2C, an inorganic insulating film is deposited on the substrate 200 to form an interlayer insulating film 240 having a predetermined thickness, and the interlayer insulating film 240 and the gate insulating film 220 are photographed. Etching is performed to form contact holes 256 and 258 exposing portions of the source region 232 and the drain region 236.

Subsequently, as illustrated in FIG. 2D, after depositing a conductive material on the interlayer insulating layer 240 including the contact holes 256 and 258, the conductive material is patterned to form a source region 232 through the contact hole 256. ) And a drain electrode 254 connected to the drain region 236 through the source electrode 252 and the contact hole 258. In this case, molybdenum (MoW) or aluminum-neodymium (Al-Nd) may be used as the conductive material.

Next, as shown in FIG. 2E, the planarization film 250 is formed on the entire surface. The planarization film 250 may include an organic insulating film such as acrylic or an inorganic insulating film such as silicon oxide. Drain electrodes 252 and 254 are formed on the entire upper surface of the substrate 200 on which the drain electrodes 252 and 254 are formed.

Subsequently, as shown in FIG. 2F, the planarization layer 250 is photo-etched to remove any of the source electrode 252 or the drain electrode 254 from the planarization layer 250, for example, the drain electrode 254. A via hole 265 is formed to expose a portion. This is for connecting the lower electrode 272 and the drain electrode 254 to be formed in a subsequent process.

Next, as shown in FIG. 2G, any one of the source / drain electrodes 252 and 254 may be deposited through the via hole 265 by depositing a conductive material on the planarization film 250 having a flat top surface including the via hole 265. For example, the lower electrode 272 connected to the drain electrode 254 is formed.

The lower electrode 272 including the first reflective film 270 is formed on the substrate 200, and the first reflective film 270 emits light emitted from the organic film 290 formed in a subsequent process. To reflect in the opposite direction. Here, the lower electrode 272 serves as an anode electrode.

In this case, the material of the first reflective film 270 is a single metal of silver (Ag), aluminum (Al), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), and thallium (Ta). And alloys thereof. Indium tin oxide (ITO) or indium zinc oxide (IZO) having a high work function may be used as a constituent material of the transparent electrode of the lower electrode 272. In consideration of its function, aluminum (Al) or its alloys and ITO are most widely used.

Subsequently, a pixel definition layer (not shown) is formed over the entire surface. In this case, the pixel definition layer may be formed of one material selected from the group consisting of polyimide, benzocyclobutene series resin, phenol resin, and acrylate. have. The thin film as described above can be patterned by a photolithography process performed by an exposure and development process.

Next, as illustrated in FIG. 2H, the pixel definition layer is patterned by a photolithography process to form a pixel definition layer pattern 280 that exposes a light emitting area, and then a lower electrode exposed by the pixel definition layer pattern 280. An organic film 290 including at least an organic light emitting layer on a surface of 272 is formed on the lower electrode 272.

Next, an upper electrode 300 is formed on the organic layer 290 on the substrate 200. The upper electrode 300 is opaque reflection type thick, the upper electrode 300 has a light extraction portion (I) is formed in the center and the upper electrode 300 is located outside the light extraction portion (I) Done.

In order to increase the light emitting area, the light extracting part I is preferably formed in a circular shape at the center of the light emitting layer which forms a light emitting area having a pixel portion (9 shown in FIG. 1), and an organic light emitting display device. In order to ensure the aperture ratio of the pixel portion 9, at least 30% or more of the area of the pixel portion 9, and 40% or less in order to be able to function as a mirror. That is, the size of the pixel portion 9 is 3/10 to 2/5 of the diameter.

If the thickness of the upper electrode 300 is 800 Å or less, it is difficult to have a mirror function due to transmission of external light when the power is turned off, and when it is formed at 3,000 Å or more, the deposition time is delayed, the problem of material consumption and the light extraction Bars may cause problems such as delay time during etching for forming part (I). Preferably, the thickness of the upper electrode 300 is preferably 800 Å to 3000 Å or less. In addition, the upper electrode 300 is formed of a reflective electrode, but a conductive metal having a low work function, and formed of one material selected from the group consisting of Mg, Ca, Al, Ag, and alloys thereof.

The upper electrode 300 of the light extraction unit I is formed to a thickness of 800 Å or less in order to allow the light generated from the organic layer 290 including the organic light emitting layer to pass therethrough. When the thickness of the upper electrode 300 is 800 kPa or more, since light generated in the organic layer 290 is difficult to transmit, the thickness of the light extracting portion I is formed to 800 kPa or less.

Subsequently, a passivation film 302 may be formed on the upper electrode 300 including the light extracting portion (I).

3A and 3B are cross-sectional views when the thickness of the upper electrode of the light extraction unit I is 0 에서 in the organic light emitting display device according to the exemplary embodiment of the present invention.

Referring to FIG. 3A, when the thickness of the upper electrode in the light extraction unit I is formed to be 0Å, that is, when the light extraction unit I is opened, the upper electrode is formed below the light extraction unit I. As shown in FIG. 2B, a passivation film 302 is formed on the upper electrode 300 including the light extracting portion I to protect the organic film 290.

(Example 2)

4 is a cross-sectional view of an organic light emitting display device according to another embodiment of the present invention.

Example 2 according to the present invention is different from the structure of the upper electrode (300 of FIG. 2H) of the first embodiment, and the process of forming up to the organic film 290 except for the upper electrode 300 is shown in FIGS. Bars may be applied in the same manner as in FIG. 2G. Hereinafter, only the structure of the upper electrode 505 will be described.

Referring to FIG. 4, an upper electrode 505 is formed on the organic layer 490, and the upper electrode 505 is formed on one side of the pixel portion (9 shown in FIG. 1) so that light can be extracted. In order to do this, the light extraction section II is opened. The upper electrode 505 includes a second reflective film 500. The central portion of the second reflective film 500 is open and light generated from the organic film 490 may be extracted toward the upper portion of the substrate 400. In order to ensure that the light extraction unit (II) is located. The second reflective film 500 is formed thick to reflect external light, and is formed of one material selected from the group consisting of Al, Ag, and alloys thereof.

An upper electrode 505 is formed on the upper portion including the second reflective film 500 and the light extracting part II. The upper electrode 505 acts as a cathode and is generated in the organic film 490 as a semi-transmissive metal. In order to allow the light to be extracted toward the upper portion of the substrate 400, a thin thickness of 50 to 100 Å is formed. The transflective metal is formed of a material such as Ag or MgAg.

As described above, according to the present invention, an opening angle is formed in a predetermined area in the center of the pixel portion of the top emission organic light emitting display and a cathode is formed outside the opening, thereby causing a viewing angle problem in the top emission organic light emitting display. And the voltage drop (IR DROP) caused by the thin transflective cathode electrode and the lifetime of the display device can be improved.

In addition, since the lower electrode and the upper electrode are formed as a reflective electrode, the pixel portion region can be used as a mirror when the power is turned off, thereby improving the merchandise and the user's convenience.

Claims (7)

A substrate having an element; A lower electrode formed on the substrate; An organic layer including at least an organic emission layer formed on the lower electrode; And And an upper electrode disposed on the organic layer and having a light extraction unit. The method of claim 1, The upper electrode has an organic light emitting display device, characterized in that formed in the thickness of 800 ~ 3000Å. The method of claim 1, An organic light emitting display device, characterized in that the thickness of the upper electrode in the light extraction portion is formed to be 800 Å or less. The method of claim 1, And a passivation layer on the organic layer and the upper electrode when the thickness of the upper electrode in the light extraction unit is 0 Å. The method of claim 1, And the light extracting portion of the upper electrode is 3/10 to 2/5 in diameter from the center of the pixel portion. A substrate having an element; A lower electrode formed on the substrate; An organic layer formed on the lower electrode and including at least an organic emission layer; And And an upper electrode disposed on the organic layer, the upper electrode including a light extraction unit and a reflective film in a region other than the light extraction unit. delete

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