KR20070037851A - Display device and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a display device and a method of manufacturing the same. A display device according to the present invention includes an insulating substrate; A thin film transistor formed on the first region on the insulating substrate; A pixel electrode connected to the thin film transistor and extending to a second region having a height lower than that of the first region; An organic layer formed on the pixel electrode of the second region; It includes a common electrode formed on the organic layer. This provides a display device manufactured by an improved method and having improved manufacturing efficiency.

Description

DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME}

1 is a cross-sectional view of a display device according to a first embodiment of the present invention;

2A to 2I are cross-sectional views sequentially illustrating a manufacturing process of a display device according to a first embodiment of the present invention, and

3 is a cross-sectional view of a display device according to a second embodiment of the present invention, and

4 is a cross-sectional view of a display device according to a third embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1, 2, 3: display device 10,11: insulated substrate

12: interlayer interlayer 20: thin film transistor

21 gate electrode 22 gate insulating film

23 semiconductor layer 24 resistive contact layer

25 source electrode 26 drain electrode

27 drain drain 31 pixel electrode

32: protective film 33: partition wall

40: organic layer 41: hole injection layer

43: light emitting layer 45: hole injection solution

50 common electrode 60 vessel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a method for manufacturing the same, and more particularly, to a display device including an organic layer having a light emitting layer and a method for manufacturing the same.

Among flat panel displays, organic light emitting diodes (OLEDs) have recently been in the spotlight due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response. OLEDs are classified into a passive matrix and an active matrix according to the driving method. Among them, the passive type has a simple manufacturing process, but the power consumption increases rapidly as the display area and resolution increase. Therefore, the passive type is mainly applied to small displays. Active type, on the other hand, has a complex manufacturing process but has the advantage of realizing a large screen and high resolution.

In the active OLED, a thin film transistor is connected to each pixel region to control the self-emission of the light emitting layer for each pixel region. Pixel electrodes are located in each pixel area, and each pixel electrode is electrically separated from an adjacent pixel electrode for independent driving. On the pixel electrode, a hole injection layer, a light emitting layer, and the like, which are organic layers, are sequentially formed.

Formation methods such as a hole injection layer, which is a common layer, include a photolithography method and an inkjet method.

Photolithography has a problem in that manufacturing efficiency is lowered because the number of processes required to form a common layer is large. The inkjet method is a method of forming a common layer by dropping a solution containing an organic composition in a predetermined region on a pixel electrode and drying it. The inkjet method has a smaller number of processes for forming a common layer than photolithography, but prevents short circuits between pixel electrodes and separates the pixel areas by allowing a solution containing an organic composition to be dropped only in each pixel area. . To this end, since the barrier layer higher than the pixel electrode must be separately formed, manufacturing efficiency is inferior as in the photolithography method.

Accordingly, it is an object of the present invention to provide a display device and a method for manufacturing the same, which are manufactured by an improved method and have improved manufacturing efficiency.

The object is, in accordance with the present invention, an insulating substrate; A thin film transistor formed on the first region on the insulating substrate; A pixel electrode connected to the thin film transistor and extending to a second region having a height lower than that of the first region; An organic layer formed on the pixel electrode of the second region; It is achieved by a display device including a common electrode formed on the organic layer.

The organic layer is composed of a plurality of layers, and at least one layer is preferably formed by a dipping method for increasing production efficiency.

The organic layer may include a hole injection layer and a light emitting layer that are sequentially stacked.

It further comprises an interlayer interlayer formed between the insulating substrate and the thin film transistor, wherein the interlayer interlayer is particularly preferably made of a photosensitive organic material to increase the manufacturing efficiency.

Even if the insulating substrate is formed to have a different thickness in the first region and the second region, manufacturing efficiency may be increased.

The common electrode extends over the thin film transistor, and further includes a passivation layer formed between the thin film transistor and the common electrode to electrically insulate both of them and prevent contamination of the thin film transistor.

The display device may further include a barrier layer formed between the passivation layer and the common electrode.

The second region is surrounded by the first region.

On the other hand, the object is, according to the present invention, the step of providing a first region on the insulating substrate, the second region having a height lower than the first region; Forming a thin film transistor on the first region; Forming a pixel electrode on the second region; Forming an organic layer on the pixel electrode; It is also achieved by a method of manufacturing a display device comprising the step of forming a common electrode on the organic layer.

The organic layer is composed of a plurality of layers, and at least one layer is preferably formed by a dipping method for increasing manufacturing efficiency.

The organic layer includes a hole injection layer and a light emitting layer that are sequentially stacked, and the layer formed by the dipping method is a hole injection layer.

The providing of the first region and the second region may further include forming an interlayer interlayer on the insulating substrate to increase manufacturing efficiency.

The preparing of the first region and the second region may include etching the insulating substrate so that the height of the second region is lower than the height of the first region.

The method may further include forming a protective film on the thin film transistor between the forming of the thin film transistor and the forming of the organic layer, to prevent contamination of the thin film transistor.

It is preferable to further form a barrier layer between the forming of the passivation layer and the forming of the common electrode in order to easily form a common layer such as a hole injection layer among organic layers by a dipping method. Do.

The organic layer may further include a hole transport layer formed by a dipping method between the hole injection layer and the light emitting layer.

Hereinafter, with reference to the accompanying drawings will be described in the present invention.

In various embodiments, like reference numerals refer to like elements, and like reference numerals refer to like elements in the first embodiment and may be omitted in other embodiments. Prior to the description, the display device according to the embodiment of the present invention is known to have a bottom emission structure.

A display device according to a first embodiment of the present invention will be described with reference to FIG. 1 is a cross-sectional view of a display device according to a first embodiment of the present invention.

The display device 1 according to the present invention includes an insulating substrate 10 having a first region and a second region surrounded by the first region, and a thin film transistor formed in the first region on the insulating substrate 10. And a pixel electrode 31 electrically connected to the thin film transistor 20 and extending to the second region, the thin film transistor 20 and the pixel electrode 31 formed in the first region. A passivation layer 32, an organic layer 40 formed on the pixel electrode 31 of the second region, a passivation layer 32, and a common electrode 50 formed on the organic layer 40. In the first embodiment, the thin film transistor 20 using amorphous silicon is illustrated, but the thin film transistor using polysilicon may be used.

Looking at the display device 1 according to the first embodiment in detail as follows.

The insulating substrate 10 is formed of an insulating material such as glass, quartz, ceramic, or plastic. The upper portion of the insulating substrate 10 is formed of a first region and a second region having a relatively lower height than the first region, and the thin film transistor 20 is formed on the first region of the upper portion of the insulating substrate 10.

The thin film transistor 20 includes a gate electrode 21, a gate insulating layer 22, a semiconductor layer 23, an ohmic contact layer 24, a source electrode 25, and a drain electrode 26.

The gate electrode 21 is made of a metal single layer or a metal multiple layer as part of a gate line (not shown).

A gate insulating film 22 made of silicon nitride (SiNx) or the like is formed on the gate electrode 21. The gate insulating layer 22 extends to the second region, but may be formed only in the first region through patterning.

A semiconductor layer 23 made of amorphous silicon and an ohmic contact layer 24 made of n + hydrogenated amorphous silicon heavily doped with n-type impurities are sequentially formed on the gate insulating film 22 where the gate electrode 21 is located. Here, the ohmic contact layer 24 is separated on both sides with respect to the gate electrode 21.

The source electrode 25 and the drain electrode 26 are formed on the ohmic contact layer 24 and the gate insulating film 22. The source electrode 25 and the drain electrode 26 are separated around the gate electrode 21.

In addition, a pixel electrode 31 electrically connected to a portion of the upper portion of the drain electrode 26 and extending to the upper portion of the gate insulating layer 22 of the second region is formed. The pixel electrode 31 is also called an anode and supplies holes to the emission layer 43 included in the organic layer 40. The pixel electrode 31 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode 31 is patterned in a substantially rectangular shape in plan view, and its thickness is not limited but is about 50 to 200 nm.

The passivation layer 32 is formed on the thin film transistor 20 and the pixel electrode 31 of the first region. The passivation layer 32 may be formed of silicon nitride (SiNx) and / or an organic layer. The passivation layer 32 is formed to have a thick thickness to distinguish between the pixel electrodes 31 without forming a partition layer, and the source electrode 25 and the drain electrode 26 of the thin film transistor 20 are connected to the common electrode 50. Short circuit can be prevented.

The organic layer 40 is formed on the pixel electrode 31 of the second region, with the boundary of the passivation layer 32 of the first region. The organic layer 40 includes a hole injecting layer 41 and a light emitting layer 43.

The hole injection layer 41 has a thickness of about 50 nm to 400 nm, of which about 200 nm is preferable and may be easily formed by a dipping method to be described later. As a material of the hole injection layer 41, for example, a mixture of polythiophene derivatives such as poly (3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) can be used.

The light emitting layer 43 emits red, green, and blue light in each pixel area. The thickness of the light emitting layer 43 is about 50 nm to 400 nm, of which about 200 nm is preferable and is formed by an inkjet method. The light emitting layer 43 includes a polyfluorene derivative, a (poly) paraphenylene vinylene derivative, a polyphenylene derivative, a polyvinylcarbazole, a polythiophene derivative, or a perylene pigment, a rhomine pigment, or ru Bren, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, nile red, coumarin 6, quinacridone and the like can be used.

Holes transferred from the pixel electrode 31 and electrons transferred from the common electrode 50 are combined in the emission layer 43 to form excitons, and then emit light in the process of deactivating excitons.

Although not shown, the display apparatus 1 may further include a hole transfer layer between the hole injecting layer 41 and the light emitting layer 43.

An opaque common electrode 50 is formed on the passivation layer 32 and the organic layer 40. The common electrode 50, also called a cathode, is made of silver (Ag), calcium, or aluminum and supplies electrons to the light emitting layer 43. The thickness of the common electrode 50 is about 50 to 200 nm.

According to the display device 1 according to the first embodiment of the present invention having the above structure, there is no barrier layer to reduce manufacturing time and manufacturing cost, and the hole injection layer 41 is simple by a dipping method. Formed in a short time, the display device 1 with improved manufacturing efficiency is provided.

Hereinafter, a method of manufacturing a display device according to a first embodiment of the present invention will be described with reference to FIGS. 2A to 2I. 2A through 2I are cross-sectional views sequentially illustrating a manufacturing process of a display device according to a first embodiment of the present invention.

First, as shown in FIG. 2A, an insulating substrate 10 including a first region and a second region having a lower height than the first region is prepared through patterning through a photolithography process. That is, after the photoresist film is applied to the upper surface of the insulating substrate 10, in the case of the positive type, the photoresist film is exposed by using a mask in which a portion corresponding to the second region is partially removed and then developed to expose the photoresist film of the portion irradiated with ultraviolet light. Remove Then, the etching solution is sprayed onto the exposed surface of the insulating substrate 10 through wet etching using one of the etching methods, and the second region portion from which the photoresist film is removed is removed to a predetermined depth, and then washed and dried. The second region is formed to have a height lower than that of the first region.

Thereafter, as shown in FIG. 2B, the thin film transistor 20 is formed on the first region of the insulating substrate 10. The thin film transistor 20 has a channel portion made of amorphous silicon and may be manufactured by a known method. Although the gate insulating layer 22 is formed on the second region, the gate insulating layer 22 may be formed only on the first region through patterning.

After forming the thin film transistor 20, as shown in FIG. 2C, an ITO or IZO or the like is sputtered on the upper portion of the drain electrode 26 of the thin film transistor 20 and the gate insulating layer 22 of the second region. After deposition, the pixel electrode 31 is formed by patterning the pixel electrode 31.

After that, as shown in FIG. 2D, the passivation layer 32 is formed on the thin film transistor 20 and the pixel electrode 31 of the first region. In order to perform the role of the barrier layer 32, the protective layer 32 must have a sufficient thickness. In the present embodiment, the protective layer 32 may be formed of an organic layer, but may be formed of a double layer of an inorganic layer and an organic layer, or may be formed of an inorganic layer.

Thereafter, as shown in FIGS. 2E to 2H, a hole injection layer 41, which is one of the organic layers 40, is formed on the pixel electrode 31 of the second region by a dipping method. Looking at the formation process of the hole injection layer 41 by the dipping method, first, the display device 1 during manufacture is put into the sol state hole injection solution 45 containing the hole injection composition as a solute. In this case, as shown in FIG. 2F, the hole injection solution 45 remains on the first area by removing the display device 1 being manufactured from the hole injection solution 45 and holding it for a predetermined time while inclining in one direction. Do not have.

Then, as shown in FIG. 2g, when the display apparatus 1 is horizontally dried and the hole injection solution 45 partially filled in the second region is dried, the solvent is removed so that the hole injection composition is a solute. As the state changes, the hole injection layer 41 is finally formed on the pixel electrode 31 as shown in FIG. 2H.

Looking at the process of removing the solvent by drying the hole injection solution 45 as follows. Drying can be performed by reducing the pressure to about 1 Torr at room temperature under a nitrogen atmosphere. If the pressure is too low, there is a risk that the hole injection solution 45 breaks rapidly. On the other hand, when the temperature is higher than or equal to room temperature, the solvent evaporation rate increases, which makes it difficult to form a film of uniform thickness, which is not preferable. There is no movement of the hole injection composition during the drying of the hole injection solution 45 so that the hole injection layer 41 formed on the pixel electrode 31 has a relatively constant thickness. After the drying is completed, heat treatment may be performed at about 200 ° C. for 10 minutes in nitrogen, preferably in vacuum, and the solvent or water remaining in the hole injection layer 41 is removed through this process.

Thereafter, one red, green, and blue light emitting layer 43 is sequentially formed on the hole injection layer 41 of each second region by a known inkjet method. As shown in FIG. 2I, the organic layer 40 is formed. The formation of is completed. Since the hole injection layer 41 has low affinity for the nonpolar solvent, when the light emitting solution (not shown) is used to form the light emitting layer 43 including the nonpolar solvent, the hole injection layer 41 and the light emitting layer 43 There exists a possibility that it may become impossible to adhere | attach or you may not be able to apply | coat the light emitting layer 43 uniformly. Therefore, in order to increase the affinity of the hole injection layer 41 with respect to the nonpolar solvent, it is preferable to undergo a surface modification process of the hole injection layer 41 before dropping the light emitting solution (not shown).

In the surface modification process, the surface modifier is applied to the hole injection layer 41 and then evaporated to dryness. The surface modifier may use cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene, or toluene or xylene similar to these solvents, which are solvents of a luminescent solution (not shown). The method of applying the surface modifier may be an inkjet method, a spin coating method or a dipping method.

Through the surface modification process, the surface of the hole injection layer 41 is easily fused to a nonpolar solvent, so that a light emitting solution (not shown) can be uniformly applied. When the drying of the light emitting solution (not shown) is completed, the light emitting layer 43 is completed. The drying process of the light emitting solution (not shown) is the same as the drying process of the hole injection solution (45).

Thereafter, silver (Ag), calcium, or aluminum is deposited on the organic layer 40 and the passivation layer 32 by a sputtering method to form a common electrode 50 having a thickness of about 50 nm to about 200 nm. ) Is completed.

Although not shown in the figure, an electron transport layer and an electron injection layer may be further included between the emission layer 43 and the common electrode 50 of the organic layer 40. In addition, a protective film for protecting the common electrode 50, a sealing member for preventing the penetration of moisture and air into the organic layer 40 may be further included. The encapsulation member may be made of a sealing resin and a sealing can.

According to the manufacturing method of the display device 1 according to the first embodiment of the present invention, it is necessary to form a barrier layer separately on the thin film transistor by forming the second region on the upper portion of the insulating substrate 10 lower than the first region. In addition, by using the dipping method, a common layer such as the hole injecting layer 41 among the organic layers 40 can be formed quickly and easily, thereby reducing manufacturing time and manufacturing cost of the display apparatus 1 and improving manufacturing efficiency. .

Hereinafter, a display apparatus according to a second embodiment of the present invention will be described with reference to FIG. 3 is a cross-sectional view of a display device according to a second embodiment of the present invention.

Unlike the display device 1 according to the first embodiment of the present invention, the display device 2 according to the second embodiment of the present invention has an insulation corresponding to the first area so that the first area is higher than the second area. An interlayer interlayer 12 is formed on the substrate 11, and the thin film transistor 20 is formed on the interlayer interlayer 12, which is a photosensitive organic material, according to a first embodiment of the present invention. Is the same as

Therefore, instead of patterning the insulating substrate 11 by photolithography to form a second region having a lower height than the first region, the photosensitive organic material is deposited on the insulating substrate 11. The manufacturing method of the display apparatus 2 is also the same except that the interlayer interlayer 12 is formed by patterning by a photolithography process such as post exposure and development.

According to the display device 2 according to the second embodiment of the present invention, it is not necessary to separately form the barrier layer, and a common layer such as the hole injection layer 41 among the organic layers 40 can be easily formed by the dipping method. It is possible to provide a display device 2 and a method of manufacturing the same, in which manufacturing efficiency is increased.

Hereinafter, a display apparatus according to a third embodiment of the present invention will be described with reference to FIG. 4 is a cross-sectional view of a display device according to a third embodiment of the present invention.

In the display device 3 according to the third embodiment of the present invention, unlike the display device 1 according to the first embodiment of the present invention, the pixel electrode 31 is formed on the passivation layer 32 in the first region. In the protective film 32, a drain contact hole 27 exposing the drain electrode 26 is formed, and is electrically connected to the drain electrode 26 through the drain contact hole 27. In addition, the barrier layer 33 is formed on the passivation layer 32 and the pixel electrode 31 in the first region. When the protective film 32 protecting the thin film transistor 20 is formed only of an inorganic film, it is not easy to form a thicker thickness than that of the organic film. Therefore, by forming a separate partition layer 33, it is possible to easily form a common layer such as the hole injection layer 41 by the dipping method.

The formation of the drain contact hole 27 and the partition wall layer 32 is by a known method, and the manufacturing method of the other display device 2 is the same as that of the first embodiment of the present invention, and thus detailed description thereof will be omitted.

The display device 3 according to the third embodiment of the present invention can also achieve the same effect as the display device 1 according to the first embodiment of the present invention.

The above embodiments can be variously modified. The display apparatuses 1, 2, and 3 according to the above embodiment may include a bottom emission structure or the common electrode 50 as a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). It may be formed to have a top emission structure.

Although some embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that modifications may be made to the embodiment without departing from the spirit or spirit of the invention. . It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, there is provided a display device manufactured by an improved method and an improved manufacturing efficiency, and a method of manufacturing the same.

Claims (17)

An insulating substrate; A thin film transistor formed on the first region on the insulating substrate; A pixel electrode connected to the thin film transistor and extending to a second region having a height lower than that of the first region; An organic layer formed on the pixel electrode of the second region; And a common electrode formed on the organic layer. The method of claim 1, The organic layer includes a plurality of layers, and at least one layer is formed by a dipping method. The method of claim 1, And the organic layer includes a hole injection layer and a light emitting layer that are sequentially stacked. The method of claim 1, And an interlayer interlayer formed between the insulating substrate and the thin film transistor. The method of claim 4, wherein The interlayer interlayer is a display device, characterized in that made of a photosensitive organic material. The method of claim 1, And the insulating substrate has a different thickness in the first region and the second region. The method of claim 1, The common electrode extends over the thin film transistor, And a passivation layer formed between the thin film transistor and the common electrode. The method of claim 7, wherein And a partition layer formed between the passivation layer and the common electrode. The method of claim 1, And the second area is surrounded by the first area. Providing a first region on the insulating substrate and a second region having a height lower than that of the first region; Forming a thin film transistor on the first region; Forming a pixel electrode on the second region; Forming an organic layer on the pixel electrode; And forming a common electrode on the organic layer. The method of claim 10, The organic layer includes a plurality of layers, and at least one layer is formed by a dipping method. The method of claim 11, The organic layer may include a hole injection layer and a light emitting layer that are sequentially stacked, and the layer formed by a dipping method is a hole injection layer. The method of claim 10, The providing of the first region and the second region may further include forming an interlayer interlayer on the insulating substrate. The method of claim 10, The preparing of the first region and the second region may include etching the insulating substrate so that the height of the second region is lower than the height of the first region. The method of claim 10, And forming a protective film on the thin film transistor between the forming of the thin film transistor and the forming of the organic layer. The method of claim 15, And forming a barrier layer between the forming of the passivation layer and the forming of the common electrode. The method of claim 12, The organic layer further comprises a hole transport layer formed by a dipping method between the hole injection layer and the light emitting layer.

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