KR100719568B1 - OLED display and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide an organic light emitting display device which can utilize an existing wiring or electrode structure as a reflective film.

To this end, the present invention includes a substrate, a wiring formed on the substrate and provided with a light reflecting material, an insulating film covering the wiring, and an organic light emitting element formed on the insulating film. An organic light emitting display device overlapping the wiring line, and the wiring line is a reflective film of the organic light emitting diode is provided.

Description

Organic light emitting display device and manufacturing method thereof

1 is a circuit diagram schematically illustrating a pixel circuit of a unit pixel of an organic light emitting diode display according to an exemplary embodiment of the flat panel display of the present invention;

2 is a circuit diagram illustrating a more specific example of FIG. 1;

3 is a plan view showing an array state of a first wiring and a pixel electrode;

4 is a plan view showing an array state of a second wiring and a pixel electrode;

5 is a cross-sectional view of an organic light emitting diode display according to an exemplary embodiment of the present invention;

6 is a cross-sectional view of an organic light emitting diode display according to another exemplary embodiment of the present invention;

7 is a cross-sectional view of an organic light emitting diode display according to another exemplary embodiment of the present invention;

8 is a cross-sectional view of an organic light emitting diode display according to another exemplary embodiment of the present invention;

9 is a plan view showing another example of an array state of a first wiring and a pixel electrode;

10 is a plan view illustrating another example of an array state of a second wiring and a pixel electrode;

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device in which a reflective film structure can be easily obtained and an aperture ratio can be improved.

The active matrix type organic light emitting diode display (AM) has a pixel circuit for each pixel, which is electrically connected to the scan line, the data line, and the power supply line. Include.

The active matrix organic light emitting diode display may further include a separate reflective film under the ITO, which is an anode, in a top-emission structure for realizing an image in the direction of the sealing member. However, the reflective film positioned below the ITO in contact with the ITO is made of a metal which is easy to oxidize, such as Al, Mg, Ag, etc., so that an oxide film is easily formed between the ITO and the ITO when forming a hole for contact between the driving thin film transistor and the ITO. Such an oxide film results in increasing the resistance of ITO and degrades contact characteristics with the driving thin film transistor.

On the other hand, the wirings connected to the pixel circuit, in particular, such as a power supply line is formed to have a somewhat thick width to prevent a voltage drop, that is, IR Drop, which is because of the double-sided light emitting structure However, there is a limit to increasing the aperture ratio. In addition, in the case of the double-sided light emission type structure, since the reflective film cannot be adopted, the light resonance structure cannot be adopted at the front side, and thus the light extraction efficiency can be reduced.

Although the structure in which the reflective film is formed using the same material as the Vdd line is disclosed in Korean Patent Laid-Open Publication No. 2005-21718 by the present applicant, since the array for the reflective film must be provided separately, the aperture ratio is low due to the array. There is a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an organic light emitting display device that can utilize a conventional wiring or electrode structure as a reflective film.

In order to achieve the above object, the present invention includes a substrate, a wiring formed on the substrate, provided with a light reflection material, an insulating film covering the wiring, and an organic light emitting element formed on the insulating film The organic light emitting diode is overlapped with the wiring, and the organic light emitting diode is provided as a reflective film of the organic light emitting diode.

In order to achieve the above object, the present invention also provides a substrate, a thin film transistor formed on the substrate and having a source / drain electrode and a gate electrode, and a reflective film electrically connected to the source / drain electrode or the gate electrode. The present invention provides an organic light emitting display device including an insulating film covering the thin film transistor and the reflective film, and an organic light emitting element formed on the insulating film and positioned on the reflective film.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically illustrates a pixel circuit PC of one unit pixel of an organic light emitting diode display of the present invention.

As shown in FIG. 1, each pixel includes a Vdd power line Vdd in which a data line Data and a scan line serve as one driving power of an organic light emitting diode (OLED).

The pixel circuit PC of each pixel is electrically connected to the data line Data, the scan line, and the Vdd power line Vdd, and controls the light emission of the OLED.

FIG. 2 illustrates a more specific example of FIG. 1, in which the pixel circuit PC of each pixel includes two thin film transistors M1 and M2 and one capacitor unit Cst.

Referring to FIG. 2, each pixel of the organic light emitting diode display according to the exemplary embodiment of the present invention may include a switching TFT M2, at least two thin film transistors of the driving TFT M1, and a capacitor unit Cst. And an organic electroluminescent element (OLED).

The switching TFT M2 is turned on / off by a scan signal applied to the scan line Scan to transfer a data signal applied to the data line Data to the storage capacitor Cst and the driving TFT M1. The switching element is not necessarily limited to the switching TFT M2 as shown in FIG. 4, and may include a switching circuit including a plurality of thin film transistors and capacitors, and a circuit that compensates for the Vth value of the driving TFT M1. Alternatively, a circuit for compensating for the voltage drop of the driving power source Vdd may be further provided.

The driving TFT M1 determines the amount of current flowing into the organic light emitting element OLED according to the data signal transmitted through the switching TFT M2.

The capacitor unit Cst stores a data signal transmitted through the switching TFT M2 for one frame.

In the circuit diagram according to FIG. 2, the driving TFT M1 and the switching TFT M2 are illustrated as PMOS TFTs, but the present invention is not limited thereto, and at least one of the driving TFT M1 and the switching TFT M2 is not limited thereto. Can be formed of an NMOS TFT, of course. In addition, the number of the thin film transistors and capacitors as described above is not necessarily limited thereto, and of course, a larger number of thin film transistors and capacitors may be provided.

3 and 4 illustrate the relationship between the wiring and the organic light emitting device which are one feature of the present invention, and illustrate the relationship between the pixel electrode and the wiring of the organic light emitting device.

1 and 2 described above, the data line Data, the scan line, the Vdd power line Vdd, and the like penetrate the pixels horizontally or vertically. FIG. 3 shows the first wiring 10 arranged in the longitudinal direction and the pixel electrode 111 positioned thereon, and FIG. 4 shows the second wiring 20 arranged in the lateral direction and positioned thereon. The pixel electrode 111 is shown.

1 and 2, the first wiring 10 may be a data line Data or a Vdd power line Vdd, and the second wiring 20 may be a scan line. It is not necessarily limited thereto, and the wirings may be formed in various shapes that are zigzag according to the layout of the pixels.

In FIGS. 3 and 4, the first wiring 10 and the second wiring 20 are illustrated to overlap the entire pixel electrode 111. However, the present disclosure is not limited thereto and overlaps with a portion of the pixel electrode 111. You may. In consideration of the design layout and the light extraction efficiency, the first wiring 10 and the second wiring 20 can be overlapped with the pixel electrode 111 to an extent sufficient to function as a reflective film.

In the present invention, the first wiring 10 and the second wiring 20 may be formed of a material capable of light reflection, and is preferably formed of a material having good electrical conductivity. It is preferable to be provided with metal materials such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and compounds thereof.

Since the width of the first wiring 10 and the second wiring 20 is larger than the minimum width of the pixel electrode 111, the first wiring 10 and the second wiring 20 are sufficient to function as a reflective film in a top-emission structure. Hereinafter, a specific structure will be described as an example.

According to the embodiment of FIG. 5, the driving thin film transistor M1 and the Vdd power line Vdd are provided on the substrate 100, and the passivation film 108 is formed to cover the passivation film 108. An organic light emitting diode OLED is formed on the substrate.

The substrate 100 may use a glass material, but is not limited thereto, and may also use a plastic material, and may use a metal material such as SUS and Ti.

A buffer layer 101 made of an organic compound and / or an inorganic compound is further formed on the upper surface of the substrate 100. Preferably, the substrate 100 is formed of SiOx (x ≧ 1) or SiNx (x ≧ 1).

After the semiconductor active layer 102 arranged in a predetermined pattern is formed on the buffer layer 101, the semiconductor active layer 102 is embedded by the gate insulating layer 103. The semiconductor active layer 102 has a source region 102b and a drain region 102c, and further includes a channel region 102a therebetween. The semiconductor active layer 102 may be formed by forming an amorphous silicon film on the buffer layer 101 and then crystallizing it to form a polycrystalline silicon film, and then patterning the polycrystalline silicon film. The source and drain regions 102b and 102c of the semiconductor active layer 102 are doped with impurities in accordance with the type of the TFT such as the driving TFT M1 and the switching TFT M2. 2 and 5 illustrate the PMOS type driving TFT M1, but the present invention is not limited thereto, and the PMOS type driving TFT M1 may be formed as an NMOS type.

A gate electrode 104 corresponding to the semiconductor active layer 102 and an interlayer insulating layer 105 embedded therein are formed on the top surface of the gate insulating layer 103.

After forming contact holes in the interlayer insulating layer 105 and the gate insulating layer 103, the source electrode 106 and the drain electrode 107 are respectively formed on the interlayer insulating layer 105 and the source region 102b. And the drain region 102c.

At this time, the Vdd power supply line Vdd is also formed to be electrically connected to the source electrode 106. The Vdd power line Vdd may be arranged in the form of a stripe in the longitudinal direction as shown in the first wiring 10 of FIG. 3.

The passivation film 108 is formed on the driving thin film transistor M1 and the Vdd power line Vdd, and the pixel electrode 111 of the organic light emitting diode OLED is formed on the passivation film 108. do. The pixel electrode 111 contacts the drain electrode 107 of the driving TFT M1 by the via hole formed in the passivation film 108. The passivation film 108 may be formed of an inorganic material and / or an organic material. As shown in FIG. 5, the passivation film 108 may be formed as a flattening film so that the top surface is flat regardless of the bending of the lower film. It may be formed to go along the bend. As described later, the passivation film 108 is preferably formed of a transparent insulator so as to achieve a resonance effect.

After the pixel electrode 111 is formed on the passivation film 108, the pixel defining layer 109 is formed of an organic material and / or an inorganic material so as to cover the pixel electrode 111 and the passivation film 108. The electrode 111 is opened so as to be exposed.

The organic emission layer 112 and the counter electrode 113 are formed on at least the pixel electrode 111.

The pixel electrode 111 functions as an anode electrode, and the counter electrode 113 functions as a cathode electrode. Of course, the polarities of the pixel electrode 111 and the counter electrode 113 may be reversed. It's okay.

The pixel electrode 111 may be formed of a material having a high work function, and may be formed of a transparent conductor such as ITO, IZO, In2O3, and ZnO.

The counter electrode 113 may be formed of a metal material such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and a compound thereof having a low work function. Mg, Ag or the like may be formed to be thin so as to be a transflective film.

The pixel electrode 111 and the opposite electrode 113 are insulated from each other by the organic layer 112, and light is emitted from the organic layer 112 by applying voltages having different polarities to the organic layer 112.

The organic layer 112 may be a low molecular or high molecular organic film. When using a low molecular organic film, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL) : Electron Injection Layer) can be formed by stacking single or complex structure, and usable organic materials are copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N '-Diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), tris-8-hydroxyquinoline aluminum ( Alq3) can be used in various ways. These low molecular weight organic films are formed by the vacuum deposition method. In this case, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer and the like can be commonly applied to red, green, and blue pixels as a common layer. Thus, unlike FIG. 5, these common layers may be formed to cover all pixels, such as the counter electrode 113.

In the case of the polymer organic film, the structure may include a hole transporting layer (HTL) and a light emitting layer (EML). In this case, PEDOT is used as the hole transporting layer, and polyvinylvinylene (PPV) and polyfluorene are used as the light emitting layer. Polymer organic materials such as (Polyfluorene) are used and can be formed by screen printing or inkjet printing.

The organic layer as described above is not necessarily limited thereto, and various embodiments may be applied.

After the organic light emitting diode OLED is formed, the organic light emitting diode OLED is sealed and shielded from outside air.

Meanwhile, in the present invention, the Vdd power line Vdd and the pixel electrode 111 are arranged to have a structure overlapping each other as shown in FIG. 3. Therefore, the Vdd power supply line Vdd functions as a reflecting film. In this case, when the distance R between the Vdd power line Vdd and the counter electrode 113 is adjusted to adjust the resonance distance, the light emitted from the organic layer 112 causes the Vdd power line Vdd and the counter electrode ( After the light resonance is generated between 113, the light extraction efficiency may be further improved by being taken out in the direction of the counter electrode 113. Therefore, it is not necessary to carry out a separate process for forming the reflective film.

Meanwhile, in the present invention, the Vdd power line Vdd may be formed separately from the source electrode 106 of the driving TFT M1. That is, as shown in FIG. 6, the first passivation film 108a is formed to cover the driving TFT M1, and after the Vdd power line Vdd is formed on the first passivation film 108a, it is again formed. After forming the second passivation film 108b so as to cover, the pixel electrode 111 is formed on the second passivation film 108b. In this case, since the Vdd power line Vdd is less affected by the array structure of the driving TFT M1, the width thereof can be sufficiently wide, thereby preventing the voltage drop IR drop phenomenon. As a result, the pixel electrode 111 can also be formed to the wide range of the left and right design margins of the Vdd power supply line Vdd, and the aperture ratio can be greatly improved.

The above description has been made of an embodiment in which the Vdd power line Vdd is used as the wiring to be a reflective film, but the present invention is not necessarily limited thereto.

FIG. 7 illustrates the switching TFT M2, the data line Data, and the organic light emitting diode OLED in FIG. 2, wherein the data line Data is connected to the source electrode 206 of the PMOS type switching TFT M2. It is connected. Since the structure of the switching TFT M2 is the same as that of the above-described driving TFT M1, the description thereof is omitted.

In the exemplary embodiment of FIG. 7, the relationship between the data line Data and the pixel electrode 111 may also be arranged in the form of FIG. 3. Therefore, at this time, the data line Data serves as a reflection film, and a resonance structure is formed between the data line Data and the counter electrode 113.

8 is an array of the scan line Data and the pixel electrode 111 as shown in FIG. 4, and the scan line Data may be formed of the same material at the same time as the gate electrode 204. In this case, the scan line Scan serves as a reflection film, and a resonance structure is formed between the scan line Scan and the counter electrode 113.

Even in the case where the data line and the scan line are used as the reflective film, as shown in FIG. 6, the passivation film is divided into the first and second passivation films, and the data line and the scan line Scan are divided. The source electrode 206 may be formed on the first passivation layer separately from the source electrode 206.

As described above, the image shows the top emission type structure in which the image is implemented in the direction of the counter electrode 113. The present invention is not limited to the top emission type structure, and the image is the direction of the counter electrode 113 and the substrate. The same may be applied to the double-sided light emitting structure implemented in the direction of 100.

9 and 10 illustrate an example in which the present invention is applied to a double-sided light emitting structure. FIG. 9 illustrates a relationship between the first wiring 10 and the pixel electrode 111, and FIG. 10 shows a second wiring 20. The relationship between the pixel electrodes 111 is shown.

In the double-sided light emission type structure, the first wiring 10 and the second wiring 20 are formed to be narrower than the width of the pixel electrode 111, so that the first wiring 10 and the second wiring 20 and the pixel electrode 111 are formed. In this overlapping portion, the resonance effect of the front emission is obtained to improve the light efficiency on the front emission side, and in the part where the first wiring 10 and the second wiring 20 and the pixel electrode 111 do not overlap, the image is generated by the back emission. You can do it.

The structure at this time is shown in FIG. 11. In FIG. 11, as shown in FIG. 5, the structure in which the Vdd power supply wiring Vdd is used as the reflecting film is shown as an example, and the portion of the image is enlarged. It is a cross section.

As shown in FIG. 11, in the portion where the Vdd power line Vdd and the organic light emitting diode OLED overlap, the light efficiency of the front emission side may be improved by the Vdd power line Vdd. In other words, the conventional double-sided light emitting structure could not adopt the reflective film, and therefore, the resonance structure could not be adopted on the front light emitting side. However, according to the present invention, the light emitting efficiency was further improved since the reflective film was also adopted on the front light emitting side. Can be improved.

Such a structure can be applied to the embodiment according to FIGS. 6 to 8 as described above.

Although the above embodiments have been described with respect to an organic light emitting display, the present invention can be applied to various kinds of flat panel displays such as a liquid crystal display in addition to the organic light emitting display.

According to the present invention as described above, it is possible to provide an organic light emitting display device employing a reflective film, without going through a separate reflective film forming process. As a result, a resonance structure can be adopted for the front emission. In addition, the aperture ratio can be increased by the width of the reflective film.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (13)

delete delete delete delete delete delete delete Board; A thin film transistor formed on the substrate and having a source / drain electrode and a gate electrode; A reflective film electrically connected to the source / drain electrode or the gate electrode; An insulating film covering the thin film transistor and the reflective film; And And an organic light emitting element formed on the insulating layer and positioned on the reflective layer. The method of claim 8, The reflective layer is formed of the same material as the source / drain electrodes. The method of claim 8, The reflective layer is formed of the same material as the gate electrode. The method according to any one of claims 8 to 10, The organic light emitting diode includes a pixel electrode, an organic emission layer, and an opposite electrode, and the reflective layer overlaps the pixel electrode. The method of claim 11, The pixel electrode and the opposite electrode are light transmissive electrode bodies. The method according to any one of claims 8 to 10, And the insulating layer is a transparent insulator.

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