KR101889950B1 - Organic Light Emitting Display Device - Google Patents

Abstract

A thin film transistor comprising: a substrate; a gate electrode on the substrate; a semiconductor layer; a source electrode; and a drain electrode; a cathode electrode located on the thin film transistor and including a conductive layer; And an anode electrode disposed on the light emitting layer.

Organic electroluminescent display device

Description

[0001] The present invention relates to an organic light emitting display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of improving luminance and efficiency by improving the reflectivity of a cathode electrode.

2. Description of the Related Art In recent years, the importance of flat panel displays (FPDs) has been increasing with the development of multimedia. In response to this, various kinds of devices such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic light emitting display A planar display of a branch has been put into practical use.

Particularly, the organic light emitting display device has a response speed of 1 ms or less, a high response speed, low power consumption, and self light emission. In addition, there is no problem in the viewing angle, which is advantageous as a moving picture display medium regardless of the size of the apparatus. In addition, since it can be manufactured at low temperature and the manufacturing process is simple based on the existing semiconductor process technology, it is attracting attention as a next generation flat panel display device.

The organic electroluminescent display device includes a light emitting layer between an anode electrode and a cathode electrode. The holes supplied from the anode electrode and the electrons received from the cathode electrode are combined in the light emitting layer to form an exciton which is a hole-electron pair. The light is emitted by the energy generated while returning to the floor state.

In general, an organic light emitting display device can be divided into a front emission type and a back emission type according to a direction in which light emitted from a light emitting layer is emitted. In the top emission type, light is emitted toward the upper side of the substrate, and the bottom emission type is emitted toward the lower side of the substrate. In the case of the front emission type, a transparent anode electrode including a reflective layer may be disposed under the light emitting layer, or an opaque cathode electrode may be disposed under the light emitting layer so that the light emitted from the light emitting layer may be directed upward.

However, the front emission type organic light emitting display device in which the cathode electrode is disposed under the light emitting layer in the related art has a problem in that the characteristic of being reflected upward from the light emitted from the light emitting layer is poor because the surface characteristics of the cathode electrode is poor.

Accordingly, the present invention provides an organic electroluminescent display device capable of improving the surface characteristics of the cathode electrode and improving the emission luminance and the luminous efficiency.

According to an aspect of the present invention, there is provided an organic light emitting display including a substrate, a semiconductor layer disposed on the substrate, a gate electrode, a thin film transistor including a source electrode and a drain electrode, And may include a cathode electrode including a conductive layer, a light emitting layer disposed on the cathode electrode, and an anode electrode disposed on the light emitting layer.

The cathode electrode may be aluminum-neodymium (AlNd).

The conductive layer may be formed of one selected from the group consisting of Al, Mo, Ag, Cu, Cr, Ti, Ni, W, Au, (ZnO), indium tin oxide (ITO), indium zinc oxide (IZO), aluminum doped zinc oxide (AZO), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), titanium oxide (TiO ₃ ) (Ti-Ni), and alloys thereof.

The thickness of the conductive layer may be 5 to 500 Å.

The surface reflectance of the cathode electrode may be 110% or more.

The conductive layer may be located under the cathode electrode.

The conductive layer may be connected to the thin film transistor.

The anode electrode may be any one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO).

The present invention has an advantage of improving the surface characteristics of the cathode electrode and improving the luminous efficiency and light emission luminance of the organic electroluminescent display device.

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

1 is a view illustrating an organic light emitting display according to an exemplary embodiment of the present invention.

1, an organic light emitting display 100 according to an exemplary embodiment of the present invention includes a substrate 110, a gate electrode 120 disposed on the substrate 110, a semiconductor layer 130, A thin film transistor T including an electrode 135a and a drain electrode 135b; a cathode electrode 162 positioned on the thin film transistor T and including a conductive layer 161; And a light emitting layer 180 positioned on the light emitting layer 180 and an anode electrode 190 located on the light emitting layer 180.

The substrate 110 may be made of glass, plastic, or a conductive material. A buffer layer of a silicon nitride film or a silicon oxide film may be further formed on the substrate 110 to prevent foreign matter from flowing out from the substrate 110.

The gate electrode 120 may be positioned on the substrate 110.

The gate electrode 120 may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, Ne, And may be made of any one selected or an alloy thereof.

The gate electrode 120 may be formed of one selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, And may be a multilayer composed of any one or an alloy thereof. For example, the gate electrode 120 may be a double layer of molybdenum (Mo) / aluminum-neodymium (AlNd) or molybdenum (Mo) / aluminum (Al).

A gate insulating layer 125 may be disposed on the gate electrode 120. The gate insulating film 125 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

The semiconductor layer 130 may be located on the gate insulating layer 125. The semiconductor layer 130 may be formed of an inorganic material including amorphous silicon or amorphous silicon crystallized polycrystalline silicon. Alternatively, the semiconductor layer 130 may be an organic semiconductor layer made of an organic material such as pentacene, but is not limited thereto.

The semiconductor layer 130 may be doped with p-type or n-type impurities. The semiconductor layer 130 includes an impurity to form a source region and a drain region, and may include a channel region other than the source region and the drain region.

A source electrode 135a and a drain electrode 135b may be positioned on the semiconductor layer 130. [ More specifically, the source electrode 135a is located in the source region of the semiconductor layer 130, and the drain electrode 135b is located in the drain region of the semiconductor layer 130.

The source electrode 135a and the drain electrode 135b may be formed of a single layer or multiple layers and may be formed of a single layer or a single layer of molybdenum (Mo), aluminum (Al) And may be made of any one selected from the group consisting of chrome (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu)

When the source electrode 135a and the drain electrode 135b are multilayered, a double layer of molybdenum (Mo) / aluminum-neodymium (AlNd), a layer of titanium (Ti) / aluminum (Al) / titanium A triple layer of molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) or molybdenum (Mo) / aluminum-neodymium (AlNd) / molybdenum (Mo)

That is, the thin film transistor T including the gate electrode 120, the semiconductor layer 130, the source electrode 135a, and the drain electrode 135b may be positioned on the substrate 110. [

The interlayer insulating film 140 may be positioned on the substrate 110 including the thin film transistor T. [ The interlayer insulating layer 140 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof, similar to the gate insulating layer 130.

The planarization layer 140 may be disposed on the substrate 110 including the interlayer insulation layer 140. The planarization layer 140 may be formed of an organic material such as polyimide, benzocyclobutene series resin, or acrylate to alleviate the step of the lower structure. Alternatively, the planarization layer 140 may be a passivation layer, or may be a silicon nitride layer (SiNx), a silicon oxide layer (SiOx), or a multilayer thereof.

The planarization layer 140 may include a via hole 155 exposing one of the source electrode 135a and the drain electrode 135b. In the present embodiment, the drain electrode 135b may be exposed.

A conductive layer 161 and a cathode electrode 162 may be positioned on the planarization layer 140 and connected to the exposed drain electrode 135b.

The conductive layer 161 may be connected to the drain electrode 135b of the thin film transistor T to electrically connect the cathode electrode 162 and may have the same pattern as the cathode electrode 162. [

The conductive layer 161 serves to improve the roughness of the cathode electrode 162. The conductive layer 161 may be formed of a metal such as aluminum (Al), molybdenum (Mo), silver (Ag), copper (Cu) (Ti), nickel (Ni), tungsten (W), gold (Au), zinc (Zn), indium tin oxide (ITO), indium zinc oxide (IZO), aluminum doped zinc oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), titanium oxide (TiO ₃ ), titanium-nickel (Ti-Ni) alloy and alloys thereof.

The conductive layer 161 may be located under the cathode electrode 162 and may have a thickness of 5 to 500 ANGSTROM. If the thickness of the conductive layer 161 is 5 ANGSTROM or more, the pattern may be formed so as not to be short-circuited in the via hole 155 and the roughness of the cathode electrode 162 formed on the conductive layer 161 may be improved . If the thickness of the conductive layer 161 is 500 angstroms or less, the advantage of being formed in an inverted tapered shape at the edge portion of the conductive layer 161 to prevent the edge portion of the conductive layer 161 from floating have.

A cathode electrode 162 may be positioned on the conductive layer 161. The cathode electrode 162 may be made of aluminum-neodymium (AlNd) as a metal having a low work function.

Since the conductive layer 161 is disposed under the cathode electrode 162, the surface roughness of the cathode electrode 162 can be improved. Therefore, if the light is emitted from the light emitting layer formed on the cathode electrode 162 to the cathode electrode 162 in the future, the surface of the cathode electrode 162 may be flat and reflect light vertically upward.

If the surface roughness of the cathode electrode 162 is large, the surface of the cathode electrode 162 is rugged, so that the light incident from the light emitting layer is reflected by the surface of the rugged cathode electrode 162, But are scattered in many directions. Accordingly, light is emitted to the left and right sides of the cathode electrode 162, and the light emission luminance and the light emitting efficiency of the organic light emitting display device are lowered.

Therefore, in one embodiment of the present invention, the conductive layer 161 is formed under the cathode electrode 162 to improve the surface roughness of the cathode electrode 162, thereby improving the light emission luminance and the luminous efficiency of the organic light- There is an advantage that it can be improved.

A bank layer 170 including an opening 175 for exposing a part of the cathode electrode 162 may be disposed on the cathode electrode 162.

The bank layer 170 may be formed of a material such as SOG (spin on glass) which is formed by coating an organic material such as polyimide, benzocyclobutene series resin, or acrylate or a silicon oxide in a liquid form, It can be made of the same inorganic material. In addition, the bank layer 170 may have a thickness of 0.5 to 3 占 퐉.

The light emitting layer 180 may be positioned on the exposed cathode electrode 162 of the bank layer 170.

The light emitting layer 180 may emit red, green, and blue light including organic materials that emit red, green, and blue light. The light emitting layer 180 may include a plurality of organic functional layers to improve light emitting efficiency. The organic functional layers include an electron injection layer that facilitates injection of electrons from the cathode electrode, an electron transport layer that facilitates transport of electrons to the light emitting layer, a hole injection layer that facilitates injection of holes from the anode electrode, And a hole transport layer serving to easily transport the layer and the hole to the light emitting layer.

The anode electrode 190 may be positioned on the substrate 110 including the light emitting layer 180.

The anode 190 may be formed of any one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO).

Hereinafter, a method of manufacturing an organic light emitting display according to an embodiment of the present invention will be described.

2A to 2C are cross-sectional views illustrating a method of manufacturing an organic light emitting display according to an exemplary embodiment of the present invention.

Referring to FIG. 2A, a substrate 210 made of glass, plastic, or a conductive material is prepared.

A first conductive layer is deposited on the substrate 210. The first conductive layer may be formed of one selected from the group consisting of aluminum (Al), aluminum alloy (Al alloy), molybdenum (Mo), molybdenum alloy (Mo alloy), tungsten (W), tungsten silicide (WSi ₂₎ desirable. Then, the first conductive layer is patterned to form the gate electrode 220.

A gate insulating layer 225 is formed on the substrate 210 on which the gate electrode 220 is formed to insulate the gate electrode 220. The gate insulating film 225 may be formed of a silicon oxide film, a silicon nitride film, or a double layer thereof.

Next, an amorphous silicon layer is laminated on the substrate 210, or an amorphous silicon layer is laminated and a polycrystalline silicon layer is formed by crystallizing the amorphous silicon layer. Then, the semiconductor layer 230 is formed by patterning it.

Next, a second conductive layer is stacked on the substrate 210 on which the semiconductor layer 230 is formed. Here, the second conductive layer is formed of a low-resistance material for lowering the wiring resistance, and is formed of multiple layers of molybdenum tungsten (MoW), titanium (Ti), aluminum (Al), or aluminum alloy. A laminated structure of molybdenum tungsten / aluminum / molybdenum tungsten (MoW / Al / MoW) may be used as the multi-layer film. Next, the second conductive layer is patterned to form a source electrode 235a and a drain electrode 235b which are electrically connected to a certain region of the semiconductor layer 230, thereby fabricating a thin film transistor T.

Referring to FIG. 2B, an interlayer insulating layer 240, which is a passivation layer for protecting the thin film transistor T, is formed on a substrate 210 including the manufactured thin film transistor T. Referring to FIG. The interlayer insulating film 240 may be formed of a silicon oxide film, a silicon nitride film, or a double layer thereof.

Then, a planarization film 250 is formed on the interlayer insulating film 240. The planarization layer 250 may be a planarization layer for alleviating the step difference of the lower structure and may be formed of a liquid material such as polyimide, benzocyclobutene series resin, acrylate, Coating, and then curing by spin coating. Alternatively, the planarization layer 250 may be a passivation layer, or may be a silicon nitride layer (SiNx), a silicon oxide layer (SiOx), or a multilayer thereof.

Then, the planarization layer 250 is etched to form a via hole 255 exposing the drain electrode 235b.

Next, a third conductive layer is deposited on the planarization layer 250 on which the via hole 255 is formed. The third conductive layer may be formed of a metal such as aluminum (Al), molybdenum (Mo), silver (Ag), copper (Cu), chromium (Cr), titanium (Ti), nickel (Ni), tungsten (W) (ZnO), indium tin oxide (ITO), indium zinc oxide (IZO), aluminum doped zinc oxide (AZO), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), titanium oxide (TiO ₃ ) Nickel (Ti-Ni) alloys, and alloys thereof. At this time, the third conductive layer may be formed to a thickness of 5 to 500 ANGSTROM.

Next, a fourth conductive layer is laminated on the third conductive layer. The fourth conductive layer may be formed of aluminum-neodymium (AlNd) having a low work function. Then, the third conductive layer and the fourth conductive layer are patterned to form the conductive layer 261 and the cathode electrode 262.

2C, a bank layer 270 is formed on the cathode electrode 262, and an opening 275 exposing a part of the cathode electrode 262 is formed by etching a part of the bank layer 270 . In this case, the bank layer 270 may be formed by coating an organic material such as polyimide, benzocyclobutene series resin, or acrylate, or silicon oxide in a liquid form, ). ≪ / RTI > In addition, the bank layer 270 may have a thickness of 0.5 to 3 mu m.

A light emitting layer 280 is formed on the exposed cathode electrode 262 of the bank layer 270. An electron injecting layer, an electron transporting layer, a hole injecting layer and a hole transporting layer may be further formed on the upper and lower portions of the light emitting layer 280.

A fifth conductive layer is stacked on the entire surface of the substrate 210 including the light emitting layer 280 to form an anode electrode 290. The anode electrode 290 may be formed of any one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO) having high work function.

Accordingly, an organic light emitting display device according to an embodiment of the present invention can be manufactured.

Hereinafter, preferred experimental examples are disclosed to facilitate understanding of the present invention. It should be noted, however, that the following experimental examples are provided to aid understanding of the present invention, and the present invention is not limited to the following experimental examples.

Experimental Example

Molybdenum (Mo) was deposited by sputtering on a glass substrate having a thin film transistor formed thereon to a thickness of 50 ANGSTROM and aluminum-neodymium (AlNd) was deposited thereon by sputtering to a thickness of 2000 ANGSTROM on a molybdenum- A molybdenum layer and an aluminum-neodymium layer were simultaneously patterned by photolithography to form a conductive layer and a cathode electrode.

Next, red, green and blue light emitting layers were formed on the conductive layer and the cathode electrode. The host was CBP, the dopant was PIQIr (acac), the green luminescent layer was TAZ, the dopant was Ir (ppy) ₃ , and the blue luminescent layer was spiro-DPVBi.

Thereafter, indium tin oxide (ITO) was deposited to a thickness of 50 nm on the light emitting layer to form an anode electrode, thereby manufacturing an organic light emitting display.

Comparative Example

An organic light emitting display was manufactured in the same manner as in the above Experimental Example except that a molybdenum (Mo) layer was not formed.

The luminescence brightness, luminous efficiency and color coordinates of the organic light emitting display manufactured according to Experimental Examples and Comparative Examples were measured and are shown in Table 1 below. The measured luminescence brightness and luminescence efficiency are shown in Figs. 3A and 3B, respectively. (At this time, each experiment was performed two times to show the data.)

Experimental order The luminous efficiency (cd / A) Light emission luminance (cd / m 2) CIE_x CIE_y Primary Experimental Example 5.2 521 0.146 0.093 Comparative Example 3.7 345 0.149 0.089 Secondary
Experimental Example 4.6 458 0.148 0.092 Comparative Example 4.0 396 0.149 0.091

Referring to Tables 1, 3A, and 3B, it can be seen that the emissive efficiency and the light emission luminance are remarkably improved in the experimental example manufactured according to one embodiment of the present invention while showing the same color coordinates as the comparative example.

4, which is a graph showing the reflectance of an organic light emitting display manufactured according to Experimental Examples and Comparative Examples, a reflectance of 110% or more in Experiments prepared according to an embodiment of the present invention, Which is significantly increased compared to that of the second embodiment.

As described above, the organic light emitting display device according to an embodiment of the present invention includes a conductive layer formed under the cathode electrode to improve the roughness of the cathode electrode, thereby improving the reflection efficiency of reflecting light emitted from the light emitting layer to the upper side Can be improved.

Therefore, the organic electroluminescent display device of the present invention has an advantage of providing an organic electroluminescent display device having improved luminous efficiency and light emission luminance and having excellent quality.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the appended claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

1 is a view illustrating an organic light emitting display according to an exemplary embodiment of the present invention.

FIGS. 2A to 2C are views showing a manufacturing method of an organic light emitting display according to an exemplary embodiment of the present invention.

FIGS. 3A and 3B are graphs illustrating the emission luminance and the luminous efficiency of an organic light emitting display according to Experimental Examples and Comparative Examples of the present invention. FIG.

4 is a graph showing the reflectance of an organic light emitting display manufactured according to Experimental Examples and Comparative Examples of the present invention.

Claims (12)

Board; A thin film transistor including a gate electrode, a semiconductor layer, a source electrode, and a drain electrode on the substrate; A flattening film which is disposed on the thin film transistor and is formed of any one of polyimide, benzocyclobutene series resin and acrylate; A conductive layer disposed on the planarization layer; A cathode electrode disposed on the conductive layer; A light emitting layer disposed on the cathode electrode; And And an anode electrode disposed on the light emitting layer, Wherein the conductive layer is formed of one or more selected from the group consisting of molybdenum (Mo), copper (Cu), chromium (Cr), nickel (Ni), tungsten (W), gold (Au), zinc Lt; / RTI > The conductive layer is in contact with the drain electrode, the cathode electrode is in contact with the upper surface of the conductive layer, The thickness of the conductive layer is 5 to 500 ANGSTROM, The thin- The gate electrode being in contact with the substrate; A gate insulating film which contacts the gate electrode; The semiconductor layer being in contact with the gate insulating film; And And a drain electrode which is located on the semiconductor layer and contacts the other of the source electrode and the semiconductor layer, the source electrode being in contact with one side of the semiconductor layer, Further comprising an interlayer insulating film located between the thin film transistor and the planarizing film, A via hole is formed in the planarizing film and the interlayer insulating film to expose the drain electrode, Wherein the conductive layer contacts the planarization layer and the interlayer insulation layer along the via hole and contacts the drain electrode. delete delete delete delete delete delete The method according to claim 1, Wherein the anode electrode is any one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). delete delete delete delete

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