KR20080060111A - Fabricating methode of electroluminescent device - Google Patents

Abstract

A fabricating method of an organic electroluminescence device is provided to reduce failure by forming a recessed unit between protrusion units to prevent an adjacent pixel from being affected by partial deformation of a pattern due to the pressing of a printing roll. A fabricating method of an organic electroluminescence device includes the steps of: preparing a substrate(110); forming a thin film transistor(109) including a gate electrode, a source electrode, and a drain electrode on the substrate; forming an insulating layer(113) having a protrusion unit(110A) on the substrate; forming a first electrode electrically connected to the drain electrode on the insulating layer; forming an organic light emitting layer(130) on the first electrode by roll printing; and forming a second electrode on the organic light emitting layer.

Description

Manufacturing method of organic electroluminescent device {FABRICATING METHODE OF ELECTROLUMINESCENT DEVICE}

1 is a conceptual diagram showing a conventional general organic light emitting device.

2 is a band diagram of the organic light emitting device.

3 is a conceptual diagram illustrating a process of forming an organic thin film by printing an organic light emitting material on a substrate according to the prior art.

4 is a conceptual diagram illustrating a process of transferring an organic light emitting material by using a printing roll to a substrate having irregularities in order to manufacture the organic light emitting device according to the present invention.

5 is a cross-sectional view showing one pixel of an organic light emitting display device according to the present invention;

6 is a cross-sectional view showing a state in which the organic light emitting layer is printed using roll printing.

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

109: thin film transistor 110: the substrate

113: insulating film 114: organic insulating film

120: first electrode 130: organic light emitting layer

133: printing roll 140: second electrode

The present invention relates to a method of manufacturing an organic light emitting display device, and more particularly, to a method of manufacturing an organic light emitting display device by forming an unevenness on a substrate and printing an organic light emitting material on the uneven portion.

It is expected that the 21st century will be an information society, and accordingly, it is important to develop a high performance flat panel display device for multimedia because it is necessary to easily obtain information from anywhere. In particular, technology development related to device development of semiconductors and display devices is becoming important in relation to communication and computers. Among them, an organic electroluminescent device is a device that is attracting attention as a natural color display device.

1 is a conceptual diagram illustrating a conventional organic light emitting display device, and FIG. 2 is a band diagram of the organic light emitting display device.

As shown in FIG. 1, the organic light emitting diode has a structure in which a light emitting material is inserted between a metal electrode having a high work function and a low metal electrode. The metal electrode having a high work function is used as an anode 7 for injecting holes into the light emitting material and the low metal electrode is used as a cathode 3 for injecting electrons into the light emitting material.

In order to emit the emitted light to the outside of the light emitting device, one electrode uses a transparent material having almost no light absorption in the light emitting wavelength region. Indium Tin Oxide (ITO) is most commonly used as the transparent electrode, and this metal is usually used as the anode 7 into which holes are injected. As the cathode 3, a metal having a low work function is generally used to facilitate the injection of electrons.

The principle of light emission of the organic light emitting device is as follows. When holes and electrons are injected into the light emitting layer 5 at the anode 7 and the cathode 3 having a high work function, excitons are generated in the light emitting layer 5, and the excitons emit and decay. As a result, light corresponding to the energy difference between the low unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of the light emitting layer 15 shown in FIG. 2 is generated.

The color of the generated light may vary depending on the material of the organic thin film constituting the light emitting layer, and a natural color may be realized by using the organic thin film emitting red, green, or blue light.

In order to manufacture the organic light emitting device described above, a process of forming an organic thin film forming a light emitting layer on a substrate is required.

Various methods may be used to form a thin film light emitting layer having a predetermined thickness with the organic light emitting material, but in the case of a soluble organic light emitting material that can be formed in a liquid state, it may be formed by a roll printing method. The roll printing method is a method in which a material for forming a pattern on a substrate is coated on a surface of a printing roll, and then the printing roll is rotated at a predetermined pressure and speed on a first substrate to transfer the applied material onto a substrate for printing. to be.

3 is a conceptual diagram illustrating a process of forming an organic thin film by printing an organic light emitting material on a substrate according to the prior art.

First, as shown in FIG. 3A, the organic light emitting material 30 is coated on the outer circumferential surface of the printing roll 33. The process of applying the organic light emitting material 30 fills the supply container 34 with the organic light emitting material 30 to be printed on the outer circumferential surface of the printing roll 33, and then the supply container 34 filled with the organic light emitting material 30. After contacting the printing roll 30, the printing roll 30 may be rotated to apply the organic light emitting material 33 on the outer peripheral surface.

Next, as illustrated in FIG. 3B, first, a cliché 35 having a groove corresponding to a pattern to be formed is prepared, and the printing roll 33 is brought into contact with the cliché 35 to rotate. To form an organic light emitting material 30).

Thereafter, as shown in FIG. 3C, the organic light emitting material 30 pattern is transferred onto the substrate 10 by rotating the printing roll 33 coated with the organic light emitting material 30 having the pattern thereon on the substrate 10. Print

The organic light emitting diode may form a light emitting layer made of the organic light emitting material 30 through the printing method described above.

However, when the organic light emitting material 30 patterned using the above roll printing is transferred to the substrate 10 to form a thin film, the substrate 10 is applied by applying a predetermined pressure using the elasticity of the surface of the printing roll 33. Will be killed. That is, a predetermined pressure is applied to the organic light emitting material 30 to be effectively attached to the substrate 10. However, since the organic light emitting material 30 is pressurized, the organic light emitting material 30 is deformed, and the organic light emitting material 30 is formed in a wider area than the desired area on the substrate 10 to the adjacent pixel area. ) Can be transferred, which causes device defects.

In addition, the printing roll 33 is generally composed of a blanket 32 made of a silicon compound surrounding the main body 31 and the main body, the surface energy between the silicon compound blanket 32 and the substrate 10 The difference is greater than the surface energy difference between the organic light emitting material 30 and the substrate 10 to be transferred. For this reason, when the surface of the printing roll 33 contacts the substrate 10 by the pressure when the organic light emitting material 30 is to be transferred, the organic light emitting material 30 is not effectively transferred to the substrate 10. The area of contact between the substrate 10 and the printing roll 33 is reduced due to the dragging of the pattern to one side of the blanket 32 or the organic light emitting material 30 falling from the substrate 10 to generate particles. It is desirable to minimize it.

For this complex reason, the pattern can be transferred only when the thickness of the organic light emitting material, that is, the thickness of the organic thin film is greater than or equal to a predetermined thickness, that is, about 1000 nm or more. In particular, in the case of an organic light emitting material having a thickness of 500 nm or less, the thickness of the organic thin film is thin, so that the deformation of the pattern is relatively severe and the printing roll is in contact with the substrate due to the thin thickness at the boundary of the pattern of the organic thin film. There was a problem.

In order to solve the above problems, an object of the present invention is to provide a method of manufacturing a high quality organic electroluminescent device which has reduced defects by preventing the surface of the printing roll from directly contacting the substrate and minimizing the contact area.

According to an aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, the method comprising: preparing a substrate, forming a thin film transistor including a gate electrode, a source electrode, and a drain electrode on the substrate; Forming an insulating film having a protrusion on the substrate on which the thin film transistor is formed, forming a first electrode electrically connected to the drain electrode on the insulating film, and forming a first electrode on the first electrode formed on the protrusion. Forming an organic light emitting layer by roll printing; and forming a second electrode on the organic light emitting layer.

The forming of the insulating layer may include depositing an entire surface of the insulating layer on the substrate, etching and patterning the insulating layer to form a protrusion, or depositing a protective layer on the substrate, and forming an organic insulating layer on a portion of the substrate on which the protective layer is formed. Characterized in that it comprises a step of forming a protrusion.

The organic insulating layer is a low dielectric constant organic light emitting material such as benzocyclobutene (BCB) or acrylic resin (resin), it can be formed by printing or coating.

At this time, the protrusion is preferably formed so that the height is about 1㎛ ~ 4.5㎛.

The forming of the organic light emitting layer by roll printing on the first electrode may include preparing a printing roll, applying an organic light emitting material to an outer circumferential surface of the printing roll, and printing the organic light emitting material coated thereon. Contacting the roll on the cliché to form a pattern corresponding to the first electrode on the organic light emitting material of the printing roll, and transferring a pattern of the printing roll corresponding to the first electrode onto the first electrode Characterized in that consists of.

The method of forming the thin film transistor may include forming a gate electrode on the substrate, forming a gate insulating film on the gate electrode, forming an active pattern on the gate insulating film, and Forming a source electrode and a drain electrode formed on the active layer spaced apart from each other, characterized in that.

In this case, the active pattern is formed of a silicon thin film.

In order to solve the problems of the conventional invention, in order to transfer the organic light emitting material to the substrate to form an unevenness on the substrate surface to prevent the printing roll and the direct contact.

4 is a conceptual diagram illustrating a process of transferring an organic light emitting material by using a printing roll 133 to a substrate having irregularities in order to manufacture the organic light emitting device according to the present invention. Although there are various types of organic light emitting materials, the present invention describes a method of manufacturing an organic light emitting display device using a soluble organic light emitting material that can be formed in a liquid phase.

Referring to the drawings, first, as shown in Figure 4a, the organic light emitting material 130 is applied to the outer peripheral surface of the printing roll 133. The process of applying the organic light emitting material 130 fills the supply container 134 with the organic light emitting material 133 to be printed on the outer circumferential surface of the printing roll 133, and then fills the supply container 134 filled with the organic light emitting material 130. After contacting the printing roll 133, the printing roll 133 may be rotated to apply the organic light emitting material 130 to the outer circumferential surface.

Next, as shown in FIG. 4B, first, a cliché 135 having a groove corresponding to the pattern to be formed is prepared and the printing roll 133 is brought into contact with the printing roll 133 to rotate the printing roll. A pattern is formed on the organic light emitting material 130 of 133.

Subsequently, as shown in FIG. 4C, the substrate 110 is formed of a recess 110B between the protrusion 110A and the protrusion 110A where the portion corresponding to the region where the organic light emitting material 130 is to be formed is printed. And rotate the printing roll 133 coated with the organic light emitting material 130 having the pattern formed thereon in contact with the protrusion 110A of the substrate 110 to transfer the organic light emitting material 130 pattern to the substrate 110. do.

As described above, when the organic light emitting material 130 is transferred onto the substrate 110 on which only the portion where the organic light emitting material 130 is to be formed is transferred, the organic light emitting material (only the protrusion 110A protruding on the substrate 110) Since the 130 is transferred, the contact area between the surface of the printing roll 133 and the substrate 110 may be minimized.

In addition, even if the pattern of the organic light emitting material 130 is partially deformed at a predetermined pressure by the printing roll 133 is divided by the groove-shaped recess 110B formed between the protrusion 110A and the next protrusion 110A. It does not affect adjacent pixels.

Therefore, the thickness of the organic light emitting material 130 to be transferred may be adjusted to be thin, and in particular, the thickness of the thin film may be formed to 500 nm or less.

Hereinafter, with reference to the drawings will be described in detail with respect to the organic electroluminescent device is formed with unevenness according to the present invention.

5 is a cross-sectional view showing one pixel of the organic light emitting display device according to the present invention.

First, referring to the organic light emitting display device according to the present invention, the organic light emitting display device according to the present invention is formed on the first electrode 120 and the first electrode 120, the organic thin film And an organic light emitting layer 130, a second electrode 140 formed on the organic light emitting layer 130, and a thin film transistor 109 for applying a voltage to the first electrode 120.

In this case, the light emitting layer 140 may be largely divided into a single layer and a multi-layer, wherein the single layer includes the organic light emitting layer 130 between the first electrode 120 and the second electrode 140. ) Is a structure in which one light emitting layer is formed, and in the multilayer, a plurality of layers are formed between the first electrode 120 and the second electrode 140.

The multilayer double-sided organic light emitting display device may have an organic layer formed of several layers, and may include an electron transport layer, an electron transport layer, an electron transport layer, a hole transport layer, and a hole injection layer. It includes. According to the embodiment of the present invention, if necessary, the single layer or the multilayer may be configured using a roll printing method, but for convenience, only the single layer is shown in the drawings.

Although not shown, the organic light emitting diode has a unit pixel area in a matrix form defined by a gate line and a data line substantially perpendicularly intersecting on the transparent substrate 110, and a thin film transistor (TFT) 109 for each unit pixel. Is formed to apply a signal to each unit pixel. The thin film transistor 109 formed in each unit pixel includes a switching transistor (not shown) and a driving transistor. When a voltage is applied to the first electrode 120 according to a signal from the thin film transistor 109, the thin film transistor 109 is applied to each pixel. The formed organic light emitting layer 130 emits light in red (R), green (G), and blue (B) to form an image.

In this case, the switching transistor is driven by a scan signal applied to the gate line, and serves to transfer the data signal applied to the data line to the driving transistor. The driving transistor determines the voltage applied to the first electrode 120 based on the data signal transmitted from the switching transistor and the signal transmitted from the power supply line.

The driving transistor includes a gate electrode 101 formed on the transparent substrate 110, a gate insulating film 102 formed on the gate electrode 101, a semiconductor layer 103 formed on the gate insulating film 102, And a source electrode 104 and a drain electrode 105 spaced apart from each other on the semiconductor layer 103. The source electrode 104 is connected to the drain electrode 105 of the switching transistor (not shown), and the drain electrode 105 is electrically connected to the first electrode 120.

An insulating layer 113 is formed between the drain electrode 105 and the first electrode 120, and the first electrode 120 is electrically connected through the contact hole 118 formed in the insulating layer 113.

In this case, the insulating layer 113 is formed on the substrate 110 to have a predetermined thickness or more in a region where the organic light emitting layer 130 is formed to form the unevenness of the protrusion 110A and the depression 110B. In this case, the protrusion 110A is formed in a region where the organic light emitting layer 130 is formed, and is preferably formed to have a height sufficient to prevent the surface of the printing roll 133 from contacting the recess 110B. At this time, the thickness of the insulating film 113 can be variously changed as necessary, but is preferably 1㎛ ~ 4.5㎛.

The insulating layer 113 is formed by forming a protective layer 112 to a sufficient thickness on the entire surface of the substrate 110 on which the source / drain electrodes are formed and patterning the protective layer 112 to have irregularities. Alternatively, the protective layer 112 may be formed to a predetermined thickness, and then the organic insulating layer 114 pattern may be formed to a sufficient thickness on the protective layer 112.

Next, a method of manufacturing an organic light emitting display device having the above configuration will be described with reference to FIG. 5.

First, a substrate 110 made of an insulating material is prepared, and a thin film transistor 109 is formed on the substrate 110. The thin film transistor 109 is provided as a switching element for applying a voltage to the first electrode 120 according to a signal.

In order to form the thin film transistor 109, first, the gate electrode 101 is formed on the substrate 110. The gate electrode 101 may be formed by depositing a conductive material on the entire surface of the substrate 110 and patterning the same through a photolithography process.

Thereafter, a gate insulating film 102 is formed on the entire surface of the substrate 110.

In addition, an amorphous silicon thin film or a polysilicon thin film is formed on the gate electrode 101 to form an active layer 103.

Next, a source electrode 104 and a drain electrode 105 spaced apart from the source electrode 104 by a predetermined distance are formed on the predetermined region of the active layer 103. The source electrode 104 and the drain electrode 105 may be formed through a photolithography process after depositing a conductive material on the substrate 110.

Next, the insulating film 113 having the protrusion 110A is formed on the substrate 110 on which the thin film transistor 109 is formed. The insulating film 113 having the protrusion 110A is formed to minimize contact with the printing roll 133 and to prevent deformation of the pattern during the printing process for forming the organic light emitting layer 130.

The protrusion 110A is formed only in a region where the organic light emitting layer 130 is printed, and a portion where the thin film transistor 109 is formed is formed as a recess 110B that does not protrude between the protrusion 110A and the protrusion 110A. do.

In order to form the insulating layer 113 having the protrusion 110A, the protrusion 110A is formed by depositing and then etching the insulating layer 113 on the substrate 110 on which the thin film transistor 109 is formed. In this case, the insulating film 113 may use silicon nitride (SiNx), silicon oxide (SiO 2), or the like, which is an inorganic insulating material.

In addition, the insulating layer 113 having the protrusion 110A may be formed by forming a protective layer 112 as an inorganic insulating layer and further forming an organic insulating layer 114 on the protective layer 112.

In this case, the organic insulating layer 114 may be formed by a printing or coating method using a low dielectric constant organic light emitting material 130 such as benzocyclobutene (BCB) or acrylic resin (resin).

At this time, in forming the insulating film 113 having the protrusions 110A, the height of the protrusions 110A is formed at a sufficient height so that the surface of the printing roll 133 does not come into contact with the depressions 110B. Preferably, from the recessed portion, the protrusion 110A is formed to have a height of about 1 μm to 4.5 μm.

Thereafter, a first electrode 120 is formed on the insulating layer 113 to be connected to the drain electrode 105. In this case, a contact hole 118 for connecting the first electrode 120 and the drain electrode 105 may be formed on the insulating layer 113 by photolithography. The first electrode 120 is formed of a conductive material and is connected to the drain electrode 105 through the contact hole 118 to receive a signal from the thin film transistor 109 to drive the organic light emitting layer 130 to be formed later. Done. In this case, the first electrode 120 is formed on the protrusion 110A according to the shape of the protrusion 110A of the lower insulating layer.

When the first electrode 120 is formed on the substrate 110, the organic light emitting layer 130 is formed by roll printing on the first electrode 120 formed on the protrusion 110A.

Then, the organic light emitting layer 130 is formed by roll printing on the first electrode 120. 6 shows a state in which the organic light emitting layer 130 is printed by using roll printing.

Referring to the drawings, the step of forming the organic light emitting layer 130 by roll printing on the first electrode 120, preparing a printing roll 133, the organic light emitting material (on the outer peripheral surface of the printing roll 133) 130 is applied, and then the printing roll 133 coated with the organic light emitting material 130 is contacted on the printing roll 133 to contact the organic light emitting material 130 of the printing roll 133 with the first electrode ( A pattern corresponding to 120). Then, the pattern of the printing roll 133 corresponding to the first electrode 120 is transferred onto the first electrode 120.

The organic light emitting layer 130 may separately print the organic light emitting material 130 corresponding to red (R), green (G), and blue (B) with a printing roll 133, and the order is necessary. Can be adjusted according to. At this time, the organic light emitting layer 130 by one transfer by applying all the patterns of the organic light emitting material 130 corresponding to the red (R), green (G), blue (B) to one printing roll 133 May form.

Next, the second electrode 140 is formed of a conductive material on the substrate 110 on which the organic light emitting layer 130 is formed.

The organic light emitting display device formed by the above method is classified into a back light emitting type and a front light emitting type according to the light emitting surface. In the bottom emission type, the first electrode 120 is made of a transparent material, and the second electrode 140 is made of an opaque material, and thus the organic light emitting layer 130 of the substrate 110 is not formed, that is, the substrate 110. It refers to a form in which the light is emitted to the back side, the front emission type is the first electrode 120 is an opaque material, the second electrode 140 is formed of a transparent material to emit light to the front of the substrate 110 Say the form.

In the organic light emitting device according to the present invention, both a top light emitting type and a bottom light emitting type are possible.

In this case, when the first electrode 120 is formed of metal, and the second electrode 140 is formed of indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive material, an organic light emitting diode having a top emission type It becomes an element. At this time, the first electrode 120 has a small work function and becomes a cathode for emitting electrons, and an electrode such as ITO has a large work function and serves as an anode.

On the contrary, when the first electrode 120 is formed of ITO or the like, and the second electrode 140 is formed of metal, the organic light emitting device of the bottom emission type is formed, and the second electrode 140 is a cathode. One electrode 120 becomes an anode.

Therefore, when forming the first electrode 120 and the second electrode 140, it is possible to manufacture by changing the material as needed.

The present invention is not limited to the above embodiments. For example, the present invention has been described in which the organic light emitting layer is formed as a single layer. However, the organic light emitting layer may be formed as a single layer, and any one of the multilayers may be formed by the method using the printing roll.

The detailed description of the invention should be construed as an illustration of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

As described above, according to the present invention, the contact area between the surface of the printing roll and the substrate is minimized, and the groove-shaped depression is formed between the protrusion and the next protrusion even if the pattern of the organic light emitting material is partially deformed by the printing roll at a predetermined pressure. Provided is a method of manufacturing an organic light emitting display device, which is divided by a part so as not to affect adjacent pixels, thereby reducing defects.

Therefore, according to the present invention, the thickness of the organic light emitting material to be transferred can be controlled to be thin, and in particular, a method of manufacturing an organic light emitting display device having a thickness of 500 nm or less is provided.

Claims (11)

Preparing a substrate; Forming a thin film transistor including a gate electrode, a source electrode, and a drain electrode on the substrate; Forming an insulating film on which a protrusion is formed on the substrate on which the thin film transistor is formed; Forming a first electrode electrically connected to the drain electrode on the insulating film; Forming an organic light emitting layer by roll printing on the first electrode formed on the protrusion; And Forming a second electrode on the organic light emitting layer manufacturing method of an organic light emitting device comprising. The method of claim 1, Forming the insulating film And depositing an entire surface of the insulating film on the substrate and etching the same to form a protrusion. The method of claim 1, Forming the insulating film Depositing a protective layer on the substrate; Forming a protrusion by forming an organic insulating film on a portion of the substrate on which the protective layer is formed. The method according to claim 2 or 3, The protrusion is characterized in that the height is formed so as to about 1㎛ ~ 4.5㎛. The method of claim 3, Forming the organic insulating film is a manufacturing method, characterized in that formed by printing or coating. The method of claim 3, The organic insulating layer is formed of a low dielectric constant organic light emitting material such as benzocyclobutene (BCB) or acrylic resin (resin). The method of claim 1, Forming the organic light emitting layer by roll printing on the first electrode, Preparing a printing roll; Coating an organic light emitting material on an outer circumferential surface of the printing roll; Contacting the printing roll coated with the organic light emitting material on a cliché to form a pattern corresponding to the first electrode on the organic light emitting material of the printing roll; And And transferring a pattern of a printing roll corresponding to the first electrode on the first electrode. The method of claim 7, The step of applying the organic light emitting material on the outer circumferential surface of the printing roll, characterized in that for applying an organic light emitting material for emitting any one of red, green, blue color. The method of claim 7, wherein The coating of the organic light emitting material on the outer circumferential surface of the printing roll is characterized in that the organic light emitting material for emitting any one of red, green, blue color to each one of the printing rolls. The method of claim 1, The method of forming the thin film transistor, Forming a gate electrode on the substrate; Forming a gate insulating film on the gate electrode; Forming an active pattern on the gate insulating film; And Forming a source electrode and a drain electrode formed on the active layer and spaced apart from each other. The method of claim 10, The active pattern is formed of a silicon thin film.

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