KR20070002640A - Organic electro-luminescence display device - Google Patents

Abstract

An organic electroluminescence element is provided to improve a life span of the organic electroluminescence element by inserting a heat sink structure into a connection unit of both electrodes of a driving thin film transistor and a light-emitting diode. An organic electroluminescence element includes a plurality of pixels having a light-emitting diode, a storage capacitor, and at least one thin film transistor. The plurality of pixels are arranged on a substrate in a matrix shape. The thin film transistor includes a poly silicon layer, a gate electrode(140), and a source/drain electrode. The poly silicon layer is formed on a predetermined region of a substrate. A central region of the poly silicon layer is defined as a channel region. Both sides of the poly silicon layer are defined as source/drain regions. A heating structure is formed on an outer circumference unit. The gate electrode(140) is formed to be corresponding to an upper part of the channel region of the poly silicon layer. The source/drain electrodes are formed to be electrically connected to the source/drain region on the upper part of the source/drain regions.

Description

Organic Electro-Luminescence Display Device

1 is a circuit diagram illustrating one pixel of a general organic electroluminescent device.

FIG. 2 is a cross-sectional view illustrating a driving thin film transistor and a light emitting diode forming portion of FIG. 1. FIG.

3 is a plan view illustrating a heat dissipation path of a semiconductor layer in the driving thin film transistor of FIG. 2.

4 is a cross-sectional view taken along line II ′ of FIG. 3.

5 is a plan view showing the shape of a semiconductor layer of a driving thin film transistor according to a first embodiment in an organic electroluminescent device of the present invention;

6 is an enlarged view illustrating an enlarged display portion of FIG. 5;

7 is a plan view showing the shape of a semiconductor layer of a driving thin film transistor according to a second embodiment in an organic electroluminescent device of the present invention;

8 is a plan view showing a shape of a semiconductor layer of a driving thin film transistor according to a third embodiment in an organic electroluminescent device of the present invention;

9 is a circuit diagram showing one pixel of the organic electroluminescent device of the present invention.

10 is a cross-sectional view showing a driving thin film transistor and a light emitting diode forming portion in the organic electroluminescent device of the present invention.

* Description of symbols on the main parts of the drawings *

100 substrate 111 buffer layer

113: gate insulating film 115: first interlayer insulating film

117: second interlayer insulating film 119: protective layer

120: semiconductor layer

121: source region 122: drain region

123: LDD region 126: channel region

128: first contact hole 129: second contact hole

130: data wiring 131: source electrode

132: drain electrode 140: gate electrode

140a: gate wiring 144: switching thin film transistor

145: driving thin film transistor 146: storage capacitor

147: light emitting diode 150: power line

157a: anode 158: cathode

159: organic fluorescent film 160: bank

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device capable of effectively dissipating heat generated in a channel of a driving thin film transistor by changing a shape of a semiconductor layer.

Currently, cathode ray tube (CRT) is used as a main device in display devices such as televisions and monitors, but this has a problem of high weight and volume and high driving voltage. Accordingly, there is a need for a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption. A liquid crystal display (LCD) and a plasma display (PDP) Various flat panel display devices such as Pane, Field Emission Display, and Electroluminescent Display (or Electro-Luminescence Display (ELD)) have been researched and developed.

The electroluminescent device is a display device using an electroluminescence (EL) phenomenon in which light is generated when a certain electric field is applied to a phosphor, and an organic electroluminescent device and an organic light emitting device according to a source causing carrier excitation. It can be divided into organic electroluminescent display (OLED).

Among them, the organic EL device is attracting attention as a natural color display device because light of all regions of visible light including blue is emitted, and has a low operating voltage characteristic with high luminance. In addition, because of self-luminous, the contrast ratio is high, the ultra-thin display can be realized, and the process is simple, and thus environmental pollution is relatively low. On the other hand, it is easy to implement a moving picture with a response time of several microseconds, there is no limitation of the viewing angle, it is stable even at low temperatures, and is driven at a low voltage of DC 5V to 15V, so that the manufacture and design of the driving circuit is easy.

The organic EL device has a structure similar to that of an inorganic EL device, but the emission principle is called organic light emitting diode (OLED) because light emission is achieved by recombination of electrons and holes. Therefore, hereinafter, referred to as organic LED.

Since the organic electroluminescent device is a self-luminous type, it has better viewing angle, contrast, and the like than a liquid crystal display, and is lightweight and thinner because it does not require a backlight, and is advantageous in terms of power consumption. In addition, since it is possible to drive DC low voltage, fast response speed, and all solid, it is strong against external shock, wide use temperature range, and especially has low cost in terms of manufacturing cost.

In particular, unlike the liquid crystal display device or the PDP, all of the deposition and encapsulation equipment may be referred to in the manufacturing process of the organic electroluminescent device, and thus the process is very simple.

In particular, when the organic electroluminescent LED device is driven by an active matrix method having a thin film transistor as a switching element for each pixel, the same luminance is displayed even when a low current is applied, so that low power consumption, high definition, and large size can be achieved. Has

Meanwhile, an active matrix form in which a plurality of pixels are arranged in a matrix form and thin film transistors are connected to each pixel is widely used in a flat panel display device, and an active matrix organic electroluminescent device (AMOLED) applied to the organic electroluminescent device is used. : Active Matrix Organic Light Emitting Device) will be described with reference to the accompanying drawings.

1 is a circuit diagram illustrating one pixel of a general organic electroluminescent device.

As shown in FIG. 1, one pixel of a general organic electroluminescent device may include a gate line 1 and a data line 2 defining a pixel area vertically intersecting with each other, a switching thin film transistor 4, and driving. ) Thin film transistor 5, a storage capacitor 6, and a light emitting diode 7.

Here, the gate electrode of the switching thin film transistor 4 is connected to the gate wiring 1 and the data wiring 2 of the source electrode. The drain electrode of the switching thin film transistor 4 is connected to the gate electrode of the driving thin film transistor 5, and the drain electrode of the driving thin film transistor 5 is connected to the anode electrode of the light emitting diode 7. The source electrode of the driving thin film transistor 5 is connected to the power line 3, and the cathode electrode of the light emitting diode 7 is grounded. The storage capacitor 6 is connected to the gate electrode and the source electrode of the driving thin film transistor 5.

Therefore, when the gate signal is applied through the gate wiring 1, the switching thin film transistor 4 is turned on, and the signal of the data wiring 2 is transferred to the gate electrode of the driving thin film transistor 5, thereby driving the thin film transistor. (5) is turned on, and light is output through the light emitting diode 7. At this time, the storage capacitor 6 serves to keep the gate voltage of the driving thin film transistor 5 constant when the switching thin film transistor 4 is turned off.

FIG. 2 is a cross-sectional view of the driving thin film transistor and the LED forming portion of FIG. 1.

In a typical organic electroluminescent device, as shown in FIG. 2, a buffer layer 11 of an insulating film, such as a silicon oxide film (SiO ₂ ), is formed on the entire surface of a substrate 10, and is formed on a predetermined portion above the buffer layer 11. A polysilicon layer 20 having an island shape is formed. Herein, the polysilicon layer 20 may include the channel region 21 that is not doped, the source and drain regions 22 and 23 doped with impurities, and the source / drain regions 22 and 23. ) And a lightly doped drain (LDD) region 25 formed between the channel region 21 and the channel region 21. The polysilicon layer 20 is formed by crystallizing the amorphous silicon layer.

The gate insulating layer 30 is formed on the entire buffer layer 11 including the polysilicon layer 20, and the gate electrode 42 is formed on the gate insulating layer 30 corresponding to the upper portion of the channel region 21. have.

An interlayer insulating film 50 is formed on the gate insulating film 30 including the gate electrode 42, and the interlayer insulating film 50 is formed of the source and drain regions 22 and 23 of the polysilicon layer 20. The first and second contact holes 50a and 50b respectively expose a part. Here, the interlayer insulating film 50 is formed of a double layer of the first and second interlayer insulating films 51 and 52.

A source electrode 62 and a drain electrode 63 are formed of a conductive material such as metal on a predetermined portion of the upper portion of the interlayer insulating film 50 including the first and second contact holes 50a and 50b. have. The source and drain electrodes 62 and 63 are connected to the source and drain regions 22 and 23 of the polysilicon layer, respectively, through the first and second contact holes 50a and 50b.

A protective layer 70 is formed over the entire surface of the interlayer insulating film 50 including the source and drain electrodes 62 and 63, where the protective layer 70 is a drain electrode on the second contact hole 50b. It has a third contact hole 71 exposing 63.

The first electrode 81 made of a transparent conductive material is formed in a predetermined portion of the passivation layer 70 through the third contact hole 71 and is connected to the drain electrode 63. The first electrode 81 may be an anode of a light emitting diode.

A bank 83 of an inorganic insulating film component is formed to cover a region (non-pixel region) between the first electrode 81 including an upper portion of the third contact hole 71. An organic fluorescent film 87 showing a corresponding color for each pixel is formed between the intervals 83. A second electrode 85 is formed on the entire surface of the substrate 10 including the bank 83 and the organic fluorescent film 87 to serve as a cathode of the light emitting diode.

The organic electroluminescent device includes a light emitting diode in which an organic fluorescent film 87 is formed between the first electrode 81 serving as an anode and the second electrode 85 serving as a cathode. When a forward voltage is applied to the holes, holes and electrons are injected from the first electrode 81 and the second electrode 85, respectively, and the injected holes and electrons combine to form excitons, and the excitons emit light recombination. Radiative recombination is called electroluminescence.

3 is a plan view illustrating a heat dissipation path of a semiconductor layer in the driving thin film transistor of FIG. 2, and FIG. 4 is a cross-sectional view taken along line II ′ of FIG. 3.

On the other hand, in the conventional organic electroluminescent device, since the coupling portion of the direct driving thin film transistor is directly coupled to the light emitting diode, heat generated in the driving thin film transistor is directly transmitted to the light emitting diode, thereby shortening the lifespan of the light emitting diode. .

3 and 4, in the conventional organic electroluminescent device, heat generated in the channel region 21 of the semiconductor layer 20 is spread in all directions during the operation of the driving thin film transistor, wherein the first electrode (81) Even if the bank 83 and the gate insulating film 30 formed between the semiconductor layer 20 and the gate electrode 42 are positioned above the thermal conductivity of the semiconductor layer 20, the gate insulating film ( Since much higher than SiO 2) 30, most of the heat generated in the channel region 21 of the semiconductor layer 20 is directly transferred to the first electrode (light emitting diode) through the drain region 23 and the drain electrode 63. Of anodes) is delivered to (81). Concentration of heat generated in the driving thin film transistor in the light emitting diode is a major cause of deterioration of the life of the organic electroluminescent device.

Reference numeral 42, which is not described in the drawing, represents a gate electrode, 50a represents a source electrode 62 in contact with the source region 22 of the semiconductor layer, and 50b represents a drain electrode in contact with the drain region 23 of the semiconductor layer ( 63).

The conventional organic electroluminescent device as described above has the following problems.

That is, the channel region of the driving thin film transistor is operated at a high temperature when the pixel of the organic electroluminescent device is driven, and heat according to this temperature is concentrated on the first electrode of the light emitting diode, which has a fatal effect on the lifetime of the light emitting diode. Therefore, there is a need for a structure for effectively dissipating heat.

An object of the present invention is to provide an organic electroluminescent device capable of effectively dissipating heat generated in a channel of a driving thin film transistor by changing the shape of a semiconductor layer to solve the above problems.

The organic electroluminescent device of the present invention for achieving the above object includes a plurality of pixels arranged in a matrix form on a substrate, the pixel is an active matrix including a light emitting diode and a storage capacitor and at least one thin film transistor In the organic electroluminescent device, the thin film transistor is formed on a predetermined portion on a substrate, the center is defined as a channel region, both sides are defined as a source / drain region, and a polysilicon layer having a heat dissipation structure at an outer portion thereof; A gate electrode formed to correspond to an upper portion of a channel region of the polysilicon layer and a source / drain electrode formed to be electrically connected to the source / drain region on an upper side of the source / drain region.

The heat dissipation structure of the polysilicon layer is formed outside the source / drain region.

The heat dissipation structure is formed of one or more heat dissipation fins integrally with the source / drain regions of the polysilicon layer.

When one or more of the plurality of heat radiation fins, each fin is formed spaced apart from each other.

The spacing of the pins is at least 2㎛ apart.

The heat dissipation fin is formed in a rectangular shape.

The heat dissipation structure of the polysilicon layer is formed at the junction of the source / drain region and the channel region.

The heat dissipation structure is formed in the channel width direction at the junction of the source / drain region and the channel region.

The heat dissipation structure of the polysilicon layer is formed by elongating the junction between the drain region and the channel region.

The junction of the drain region and the channel region is formed in a '-' shape.

The width of the junction portion between the drain region and the channel region is 4 μm or less.

The pixel includes a switching thin film transistor and a driving thin film transistor.

The light emitting diode includes an anode, a cathode, and an organic fluorescent film interposed therebetween, and the anode is connected to a drain electrode of the driving thin film transistor.

Hereinafter, the organic electroluminescent device of the present invention will be described in detail with reference to the accompanying drawings.

The organic electroluminescent device of the present invention changes the structure of the portion where the light emitting diode and the driving thin film transistor are connected to form a heat dissipation structure, thereby minimizing the influence of heat generated from the thin film transistor on the light emitting diode and thus life of the organic electroluminescent device. Can improve.

First Embodiment

5 is a plan view illustrating the shape of a semiconductor layer of a driving thin film transistor according to a first embodiment in an organic electroluminescent device of the present invention, and FIG. 6 is an enlarged view illustrating an enlarged display portion of FIG. 5.

5 and 6, in the organic electroluminescent device of the present invention, the heat dissipation fins 121a and 122a are inserted into the source / drain regions 121 and 122 of the semiconductor layer of the driving thin film transistor according to the first embodiment. Thus, heat generated in the channel region (see 126 of FIG. 10) can be effectively transmitted to the outside.

In the organic electroluminescent device of the present invention, the semiconductor layer 120 of the driving thin film transistor is formed of a polysilicon layer, and a center thereof is defined by a channel region (a portion corresponding to the lower portion of the gate electrode 140) 126. And both sides are defined as source / drain regions 121 and 122 doped with a high concentration of impurities, and an area between the channel region 126 and the source / drain regions 121 and 122 is LDD (Lightly Doped Drain). It is defined as an area.

In the first embodiment, the heat dissipation fins 121a and 122a of the semiconductor layer are integrally formed with the source / drain regions 121 and 122, respectively, and have a rectangular shape. The heat dissipation fins 121a and 122a are formed at the outer side of each side of the source / drain regions 121 and 122 not in contact with the LDD region (pin dimension), and the shape of the heat dissipation fins 121a and 122a is illustrated in FIG. 6. The heat dissipation fins 121a and 122a are formed in a rectangular shape as shown in Fig. 2. The more heat dissipation fins 121a and 122a are formed and the larger the area is, the better the heat dissipation effect is. (c) The length is formed in about 2㎛, the separation distance (a) between the radiating fins 121a, 122a is formed larger than 2㎛, so that heat is dispersed without being concentrated in part.

Here, the source region 121 of the semiconductor layer is in contact with a source electrode (131 of FIG. 10) formed thereon with a first contact hole 128 corresponding to the center thereof and interposed between the interlayer insulating layers. The drain region 122 of the semiconductor layer is in contact with a drain electrode 132 of FIG. 10 formed at an upper portion thereof with a second contact hole 129 corresponding to the center of the drain region 122.

In FIG. 5, reference numeral 140, which is not described in FIG. 5, refers to the gate electrode 140, and is formed on the channel region 126 of the semiconductor layer through a gate insulating layer 113 of FIG. 10.

Second Embodiment

FIG. 7 is a plan view illustrating the shape of a semiconductor layer of a driving thin film transistor according to a second embodiment in an organic electroluminescent device of the present invention. FIG.

FIG. 7 illustrates the shape of the semiconductor layer of the driving thin film transistor according to the second embodiment in the organic electroluminescent device of the present invention, wherein heat dissipation fins are formed at the source / drain junction of the semiconductor layer, and the shape thereof is shown in FIG. It is formed in the longitudinal direction of the gate electrode 140 (the width direction of the gate electrode 140).

In the illustrated semiconductor layer 220, both sides are defined as source / drain electrodes 221 and 222, a central region is defined as a channel region (see 126 in FIG. 10), and the source / drain electrodes 212 and 222 are formed. The LDD region 223 is defined between the channel regions. In addition, heat dissipation fins 221a and 222a which are integrally extended from the junctions entering the source / drain regions 221 and 222 from the LDD region 223 and extended in the width direction (vertical direction in the drawing) of the gate electrode are formed. . In this case, the width of the heat radiation fin is formed within 2㎛. In this case, the LDD region may be omitted.

The second embodiment of the present invention is the same as the first embodiment except for the shape and arrangement of the heat radiation fins described in the first embodiment.

On the other hand, in order to increase the heat dissipation effect, the structure of the first embodiment (the rectangular heat dissipation fins are formed outside the source / drain regions of the semiconductor layer) and the structure of the second embodiment (the junction of the source / drain region and the channel region of the semiconductor layer) It may be configured by mixing the heat radiation fins on the outside).

Third embodiment

8 is a plan view showing the shape of a semiconductor layer of a driving thin film transistor according to a third embodiment of the organic electroluminescent device of the present invention.

FIG. 8 illustrates the shape of the semiconductor layer 320 of the driving thin film transistor according to the third embodiment in the organic electroluminescent device of the present invention, wherein the heat dissipation fin is formed in the channel region of the semiconductor layer 320 (126 of FIG. 10). The shape of the junction part connected to the drain region 322 is formed long, and the heat generating area is increased. In this case, the semiconductor layer

It is formed in the source / drain junction of the semiconductor layer, and the shape is formed in the longitudinal direction (width direction of the gate electrode 140) of the gate electrode 140 shown above.

The illustrated semiconductor layer 320 has both sides defined as source / drain electrodes 321 and 322, a central region defined as a channel region (see 126 in FIG. 10), and the source / drain electrodes 312 and 322. The LDD region 325 is defined between the channel regions. In addition, a junction that enters the drain region 322 from the LDD region 325 is formed long in the shape of a letter 'L'. In this case, the junction formed by the letter 'd' functions as a heat radiation fin. At this time, the width 'e' of the 'r' shape is 4 μm or less, and the interval d between the 'r' shape patterns is formed to be 2 μm or more. In this case, the junction length of the 'f' shape is formed to a level that does not adversely affect the performance of the driving thin film transistor including the semiconductor layer 320 as the junction becomes longer.

In this case, the source region 321 contacts the upper source electrode through the first contact hole 328, and the drain region 322 contacts the upper drain electrode through the second contact hole 329. .

In the above-described first to third embodiments, the heat generating area is increased by changing the shape of the outer portion of the semiconductor layer, and the shape of the semiconductor layer is applied to not only the driving thin film transistor of the organic electroluminescent device but also the switching thin film. Applicable to transistors as well. However, above all, in the case of the driving thin film transistor in which the anode of the light emitting diode and its drain electrode are connected, since the heat during driving is directly transmitted to the anode of the light emitting diode, the structure of the semiconductor layer of the present invention is driven in the organic light emitting element. It is effective to apply to the semiconductor layer of a thin film transistor. Of course, the structure of the semiconductor layer may be applied to both the switching thin film transistor and the semiconductor layer of the driving thin film transistor.

Hereinafter, the organic electroluminescent device and the present invention will be described with reference to a circuit diagram and a cross-sectional view of the organic electroluminescent device including the semiconductor layer described above of the present invention.

FIG. 9 is a circuit diagram illustrating one pixel of the organic electroluminescent device of the present invention, and FIG. 10 is a cross-sectional view illustrating a driving thin film transistor and a light emitting diode forming portion in the organic electroluminescent device of the present invention.

As shown in FIG. 9, one pixel of the organic electroluminescent device of the present invention is in a direction parallel to the gate line 140a, the data line 130, and the data line 130, which define pixel regions perpendicular to each other. The formed power line 150, the switching thin film transistor 144, the driving thin film transistor 145, the storage capacitor 146, and the light emitting diode 147 are formed.

Here, the gate electrode of the switching thin film transistor 144 is connected to the gate line 140a and the source electrode is connected to the data line 130. The drain electrode of the switching thin film transistor 144 is connected to the gate electrode of the driving thin film transistor 145, and the drain electrode of the driving thin film transistor 145 is connected to the anode electrode of the light emitting diode 147. The source electrode of the driving thin film transistor 145 is connected to the power line 150, and the cathode electrode of the light emitting diode 147 is grounded. The storage capacitor 146 is connected to the gate electrode and the source electrode of the driving thin film transistor 145.

Therefore, when the gate signal is applied through the gate line 140a, the switching thin film transistor 144 is turned on, and the signal of the data line 130 is transferred to the gate electrode of the driving thin film transistor 145 to drive the thin film transistor. 145 is turned on, and light is output through the light emitting diode 147. In this case, the storage capacitor 146 maintains a constant gate voltage of the driving thin film transistor 145 when the switching thin film transistor 144 is off.

As shown in FIG. 10, in the organic electroluminescent device of the present invention, a buffer layer 111 of an insulating film, such as a silicon oxide film (SiO ₂ ), is formed on the entire surface of the substrate 100, and the upper portion of the buffer layer 111 is formed on the substrate 100. A polysilicon layer 120 having an island shape is formed at a predetermined portion. Herein, the polysilicon layer 120 may include the channel region 126 that is not doped, the source and drain regions 121 and 122 doped with impurities, and the source / drain regions 121, It is defined by being divided into a lightly doped drain (LDD) region 123 formed between the 122 and the channel region 126. The polysilicon layer 120 is formed by crystallizing the amorphous silicon layer.

The gate insulating layer 113 is formed on the entire buffer layer 111 including the polysilicon layer 120, and the gate electrode 140 is formed on the gate insulating layer 113 corresponding to the upper portion of the channel region 126. have.

The interlayer insulating layers 115 and 117 are formed on the gate insulating layer 113 including the gate electrode 140, and the source and drain regions 121 of the polysilicon layer 120 are formed on the interlayer insulating layers 115 and 117. And 122 have first and second contact holes 128 and 129 exposing a portion thereof.

The source electrode 131 and the drain electrode 132 may be formed of a conductive material such as a metal in a predetermined portion of the interlayer insulating layers 115 and 117 including the first and second contact holes 128 and 129. Formed. The source and drain electrodes 131 and 132 are connected to the source and drain regions 121 and 122 of the polysilicon layer, respectively, through the first and second contact holes 50a and 50b.

The protective layer 119 is formed over the entire surface of the interlayer insulating layer 117 including the source and drain electrodes 131 and 132, where the protective layer 119 is a drain electrode above the second contact hole 129. And a third contact hole 156 exposing 132.

The first electrode 157a made of a transparent conductive material is formed at a predetermined portion of the passivation layer 119 through the third contact hole 156 and is connected to the drain electrode 132. The first electrode 157a may be an anode of a light emitting diode.

In addition, a bank 160 of an inorganic insulating film component, such as SiO 2 or SiN x, is formed to cover a region (non-pixel region) between the first electrode 157a including the upper portion of the third contact hole 156. An organic fluorescent film 159 having a corresponding color for each pixel is formed between the banks 160. A second electrode 158 is formed on the entire surface of the substrate 100 including the bank 160 and the organic fluorescent film 159 to serve as a cathode of the light emitting diode. The organic fluorescent film 159 is formed by evaporating a plurality of layers, and formed below the height of the bank 160 to prevent the organic fluorescent film material from being passed to other pixel areas. . 10 is schematically illustrated. In fact, the height of the organic fluorescent film 159 is lower than that of the bank 160.

The organic electroluminescent device of the present invention as described above has the following effects.

By inserting a heat dissipation structure into the connection portion between the driving thin film transistor and the anode of the light emitting diode, the heat generated by the driving thin film transistor can be effectively released to improve the life of the organic electroluminescent device. The heat dissipation structure may form one or more heat dissipation fins at an outer portion of the source / drain region of the semiconductor layer, or may form heat dissipation fins in the width direction of the gate electrode at a junction of the semiconductor layer to increase a heat generating area on the semiconductor layer. The junction portion adjacent to the drain region of the semiconductor layer in contact with the drain electrode connected to the anode of the light emitting diode is formed long.

By inserting such a heat dissipation structure, the heat of the driving thin film transistor can be effectively released, thereby preventing heat from concentrating on the organic light emitting diode side, which will ultimately improve the life of the organic electroluminescent device.

Claims (13)

In the active matrix organic electroluminescent device comprising a plurality of pixels arranged in a matrix form on a substrate, wherein the pixels include a light emitting diode, a storage capacitor and at least one thin film transistor, The thin film transistor is A polysilicon layer formed at a predetermined portion on the substrate, a center defined as a channel region, and both sides defined as a source / drain region, and having a heat dissipation structure formed at an outer portion thereof; A gate electrode formed corresponding to an upper portion of a channel region of the polysilicon layer; And And a source / drain electrode formed on the source / drain region and electrically connected to the source / drain region. The method of claim 1, The heat dissipation structure of the polysilicon layer is formed on the outside of the source / drain region. The method of claim 2, And the heat dissipation structure is formed of at least one heat dissipation fin integrally with the source / drain region of the polysilicon layer. The method of claim 3, wherein The at least one organic electroluminescent device, characterized in that when the plurality of heat radiation fins, each fin is formed spaced apart from each other. The method of claim 4, wherein The interval between each pin is an organic electroluminescent device, characterized in that spaced apart by more than 2㎛. The method of claim 3, wherein The heat dissipation fin is an organic electroluminescent device, characterized in that formed in a rectangular shape. The method of claim 1, The heat dissipation structure of the polysilicon layer is formed in the junction of the source / drain region and the channel region. The method of claim 7, wherein And the heat dissipation structure is formed at a junction portion of the source / drain region and the channel region in a channel width direction. The method of claim 1, The heat dissipation structure of the polysilicon layer is formed by extending the junction of the drain region and the channel region. The method of claim 9, The junction of the drain region and the channel region is an organic electroluminescent device, characterized in that formed in the '' 'shape. The method of claim 10, An organic electroluminescent device, characterized in that the width of the junction between the drain region and the channel region is 4 μm or less. The method of claim 1, The pixel includes a switching thin film transistor and a driving thin film transistor. The method of claim 12, The light emitting diode includes an anode, a cathode, and an organic fluorescent film interposed therebetween, wherein the anode is connected to a drain electrode of the driving thin film transistor.

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