KR101672908B1 - Top emission type organic Electroluminescent Device - Google Patents

Abstract

The present invention provides a top emission type organic electroluminescent device that increases the transmittance of a visible light beam and reduces power consumption.

Top emission, organic field, light emitting device, internal resistance, luminance, auxiliary electrode

Description

[0001] The present invention relates to a top emission type organic electroluminescent device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device that improves the transmissivity of a transparent electrode in a structure of a top emission type to improve brightness.

An organic electroluminescent device, which is one of flat panel displays (FPDs), has high luminance and low operating voltage characteristics. In addition, since it is a self-luminous type that emits light by itself, it has a large contrast ratio, can realize an ultra-thin display, can realize a moving image with a response time of several microseconds (μs), has no viewing angle limit, And it is driven with a low voltage of 5 to 15 V direct current, so that it is easy to manufacture and design a driving circuit.

In addition, since the manufacturing process of the organic electroluminescent device is all the deposition and encapsulation equipment, the manufacturing process is very simple.

An organic electroluminescent device having such characteristics is largely divided into a passive matrix type and an active matrix type. In a passive matrix type, a scan line and a signal line cross each other to form a matrix type device, The scan lines are sequentially driven with time in order to drive the scan lines. Therefore, in order to represent the required average luminance, the instantaneous luminance must be equal to the average luminance multiplied by the number of lines.

However, in the active matrix method, a thin film transistor (a thin film transistor), which is a switching element for turning on / off a pixel, is provided for each sub pixel, and a first electrode connected to the thin film transistor On / off in units of subpixels, and the second electrode facing the first electrode is a common electrode.

In the active matrix method, the voltage applied to the pixel is charged in the storage capacitance (C _ST ), and power is applied until the next frame signal is applied. Thus, Continue to run for one screen without. Accordingly, since the same luminance is exhibited even when a low current is applied, an active matrix type organic electroluminescent device is mainly used since it has advantages of low power consumption, high definition and large size.

Hereinafter, the basic structure and operating characteristics of such an active matrix organic electroluminescent device will be described in detail with reference to the drawings.

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

As shown, one pixel of the active matrix type organic electroluminescent device includes a switching thin film transistor STr, a driving thin film transistor DTr, a storage capacitor StgC, and an organic light emitting diode E, .

That is, a gate line GL is formed in a first direction and a data line DL is formed in a second direction intersecting the first direction to define a pixel region P, A power supply line PL for applying a power supply voltage is formed.

A switching thin film transistor STr is formed at the intersection of the data line DL and the gate line GL and a driving thin film transistor DTr electrically connected to the switching thin film transistor STr is formed have. The first electrode, which is one terminal of the organic light emitting diode E, is connected to the drain electrode of the driving thin film transistor DTr, and the second electrode of the organic light emitting diode E is connected to the power supply line PL. At this time, the power supply line (PL) transfers the power supply voltage to the organic light emitting diode (E). A storage capacitor StgC is formed between the gate electrode and the source electrode of the driving thin film transistor DTr.

Therefore, when a signal is applied through the gate line GL, the switching thin film transistor STr is turned on and the signal of the data line DL is transmitted to the gate electrode of the driving thin film transistor DTr, The thin film transistor DTr is turned on so that light is output through the organic light emitting diode E. At this time, when the driving thin film transistor DTr is turned on, a level of a current flowing from the power supply line PL to the organic light emitting diode E is determined. Accordingly, the organic light emitting diode E The storage capacitor StgC is capable of maintaining a constant gate voltage of the driving thin film transistor DTr when the switching thin film transistor STr is turned off The level of the current flowing through the organic light emitting diode E can be kept constant until the next frame even if the switching thin film transistor STr is turned off.

The organic electroluminescent device that performs such driving is divided into a top emission type and a bottom emission type according to the transmission direction of light emitted through the organic electroluminescent diode. In this case, the lower light emitting method has a problem that the aperture ratio is lowered, and therefore, the upper light emitting method is mainly used.

2 is a schematic cross-sectional view of a conventional top emission type organic electroluminescence device.

As shown in the drawing, the first and second substrates 10 and 70 are disposed opposite to each other, and the edge portions of the first and second substrates 10 and 70 are sealed by a seal pattern 80 . A driving thin film transistor DTr is formed for each pixel region P on the first substrate 10 and a protective layer 40 including a drain contact hole 43 is formed on the driving thin film transistor DTr. And the first electrode 47 is connected to the driving thin film transistor DTr connected to the driving thin film transistor DTr through the drain contact hole 43 so that the first electrode 47 is formed on the protection layer 40 Respectively. An organic light emitting layer 55 including light emitting material patterns 55a, 55b and 55c corresponding to red, green and blue colors is formed on the first electrode 47 And a second electrode 58 is formed on the entire surface of the organic light emitting layer 55. [ At this time, the first and second electrodes 47 and 58 provide electrons and holes to the organic light emitting layer 55.

The second electrode (58) and the second substrate (70) formed on the first substrate (10) are separated from each other by a predetermined distance by the seal pattern (80).

3 is a cross-sectional view of one pixel region including the driving thin film transistor of the above-described organic light emitting device of the upper emission type.

A semiconductor layer 13 composed of a first region 13a of pure polysilicon and a second region 13b doped with an impurity, a gate insulating film 16, and a gate electrode (not shown) are formed on the first substrate 10, An interlayer insulating film 23 having a semiconductor layer contact hole 25 exposing the first region 13 and a second region 13b and source and drain electrodes 33 and 36 are sequentially stacked to form a driving thin film transistor DTr, And the source and drain electrodes 33 and 36 are connected to a power supply line (not shown) and the organic light emitting diode E, respectively.

The organic electroluminescent diode E includes a first electrode 47 and a second electrode 58 opposed to each other with the organic light emitting layer 55 interposed therebetween. The first electrode 47 is formed in contact with one electrode of the driving thin film transistor DTr for each pixel region P and the second electrode 58 is formed over the organic light emitting layer 55 .

In addition, the second substrate 70 is formed to encapsulate the first substrate 10 having the above-described structure to form the organic electroluminescent device 1.

The first electrode 47 may be formed of indium-tin-oxide (ITO) or indium-tin-oxide (ITO), which is a transparent conductive material having a high work function value to serve as an anode electrode when the driving thin film transistor DTr is p- - zinc oxide (IZO), and the second electrode 58 is made of a metal material having a low work function value to serve as a cathode electrode.

However, since the metal material having a low work function value constituting the second electrode 58 serving as the cathode electrode has opaque characteristics, it is preferable to use such opaque metal to have a thickness of a general electrode or insulating layer, The light can not be transmitted.

4A and 4B showing only the region A of FIG. 3, the second electrode 58 made of an opaque metal material having such a relatively low work function value is formed of an opaque metal material The lower layer 58a is formed to have a first thickness t1 of several tens to several hundreds of angstroms and a transparent conductive material is formed on the upper layer 58b with a second thickness t2 of about several thousand angstroms (FIG. 4A), or they are formed to have multiple layers (58a, 58b, 58c, 58d) structures by depositing these double layers one or two more times (FIG. 4B).

However, since the second electrode 58 has a transmittance of visible light of 40% to 60%, the transmittance of the second electrode 58 is very low. The thickness of the metal layer 58a or 58c made of a metal material having a low work function value may be made thinner than the thickness of the second electrode 58 in order to increase the transmittance of the visible light However, in this case, there is a problem that the electric conductivity is lowered and the voltage difference is generated according to the position, and the power consumption is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a top emission type organic electroluminescent device which can reduce the resistance of a second electrode itself of an organic electroluminescent diode formed in the uppermost layer, And the like.

According to an aspect of the present invention, there is provided a top emission type organic electroluminescent device including a first substrate having a pixel region defined therein; A switching thin film transistor and a driving thin film transistor formed in the pixel region on the first substrate; A protective layer covering the switching and driving thin film transistor and exposing a drain electrode of the driving thin film transistor; A first electrode formed on the protective layer in contact with a drain electrode of the driving thin film transistor; A bank formed on a boundary of the pixel region and overlapping an edge of the first electrode; An organic light emitting layer formed on the first electrode inwardly of the bank; A second electrode formed on the organic light emitting layer and over the bank; A second substrate facing the first substrate; A plurality of protrusions formed on an inner surface of the second substrate with a column shape corresponding to a boundary of the pixel region; A first layer formed of a first metal material having a low resistance characteristic and formed in a lattice shape covering the protrusions along the boundary of the pixel region and contacting the second electrode; And a second layer of a second layer of a second metal material having light absorbing properties and positioned between the second substrate and the first layer of the auxiliary electrode, And the electrodes are cemented so as to be in contact with each other.

At this time, the first metal material is one of silver (Ag), aluminum (Al), and gold (Au), and the second metal material is one of molybdenum (Mo), tungsten (W) Preferably, the protrusions are made of photo acryl, which is an organic insulating material, or polyimide, which is a high molecular material.

The switching and driving thin film transistor is a p-type thin film transistor, and the first electrode functions as an anode electrode. In this case, the first electrode may have a single layer structure of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), which is a transparent conductive material having a relatively high work function value, Layer structure composed of a first layer made of molybdenum (Mo), a second layer made of aluminum (Al), and a third layer made of the transparent conductive material and in contact with the organic light emitting layer, . The second electrode may have a single layer structure composed of one of aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold Layer structure of a first layer made of the metal material and in contact with the organic light emitting layer and a second layer made of a transparent conductive material in contact with the auxiliary electrode, The second electrode of the structure and the first layer of the second electrode of the double layer structure have a thickness of 5 to 50 Å.

The switching and driving thin film transistor is an n-type thin film transistor, and the first electrode serves as a cathode electrode. In this case, the first electrode may have a single layer structure composed of one of aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold Layer structure composed of a first layer made of molybdenum (Mo) and a second layer made of the third metal material and in contact with the drain electrode of the driving thin film transistor, And the second electrode has a single layer structure of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) which is a transparent conductive material having a relatively high work function value.

In addition, between the second substrate and the projections, indium-tin-oxide (ITO) or indium-zinc-oxide (ITO), which is made of silicon oxide (SiO ₂ ) or silicon nitride (SiNx) And a buffer layer made of oxide (IZO) is formed.

Further, a gate wiring and a data wiring crossing each other and defining the pixel region, and a power supply wiring arranged in parallel with the data wiring are formed on the first substrate, and the gate and the data wiring are connected to the gate of the switching thin film transistor And the electrode and the source electrode are connected to each other.

The top emission type organic electroluminescent device according to the present invention includes a first substrate and a second substrate on which a protrusion and the protrusions are covered, a grid-shaped auxiliary electrode is formed of a low resistance metal material, and an organic light emitting diode Even if the thickness of the second electrode is made thinner by virtue of the second electrode being in contact with the auxiliary electrode, the second electrode is hardly influenced by the internal resistance, so that there is an advantage that the voltage difference for each position hardly occurs.

In addition, since the second electrode can be formed to have a small thickness, the brightness can be improved by improving the transparency thereof.

The auxiliary electrode has an effect of reducing power consumption by lowering the internal resistance of the second electrode.

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

≪ Embodiment 1 >

FIGS. 5A and 5B are cross-sectional views illustrating a portion of a top emission type organic electroluminescent device according to a first embodiment of the present invention, which is one pixel region including a driving thin film transistor and an organic light emitting diode, 6 is a plan view showing a part of a second substrate in the top emission type organic electroluminescent device according to the first embodiment of the present invention. For convenience of description, a region where the driving thin film transistor DTr is formed is defined as a driving region DA, and a region where a switching thin film transistor is formed, not shown in the drawing, is defined as a switching region.

1, a top emission type organic electroluminescent device 101 according to the present invention includes a first substrate 110 on which a driving and switching thin film transistor DTr (not shown) and an organic electroluminescent diode E are formed, And a second substrate 170 covering the first electrode 175 and the auxiliary electrode 178 in a lattice shape.

First, the structure of the first substrate 110 will be described.

The first substrate 110 is formed of pure polysilicon corresponding to the driving region DA and the switching region and has a first region 113a and a second region 113b. And a second region 113b doped with an impurity. A buffer layer (not shown) made of an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) may be further formed on the entire surface between the semiconductor layer 113 and the first substrate 110 . The buffer layer (not shown) prevents the deterioration of the characteristics of the semiconductor layer 113 due to the release of alkali ions from the inside of the first substrate 110 when the semiconductor layer 113 is crystallized.

A gate insulating layer 116 is formed on the entire surface of the semiconductor layer 113. The gate insulating layer 116 is formed on the semiconductor layer 113 in the driving region DA and the switching region A gate electrode 120 is formed in correspondence with the first region 113a of the gate electrode 113. [ The gate insulating layer 116 is connected to a gate electrode (not shown) formed in the switching region (not shown) and extends in one direction to form a gate wiring (not shown).

An interlayer insulating film 123 is formed on the gate electrode 120 and the gate wiring (not shown). The interlayer insulating layer 123 and the gate insulating layer 116 under the semiconductor layer contact hole 125 expose the second regions 113b located on both sides of the first region 113a .

A data line 130 is formed on the interlayer insulating layer 123 including the semiconductor layer contact hole 125 to define a pixel region P intersecting the gate line (not shown) (Not shown) is formed. The source and drain electrodes 113 and 114 are in contact with the second region 113b which are spaced apart from each other in the driving region DA and the switching region (not shown) above the interlayer insulating layer 123 and exposed through the semiconductor layer contact hole 125, Drain electrodes 133 and 136 are formed. The semiconductor layer 113 includes the source and drain electrodes 133 and 136 and the second region 113b contacting the electrodes 133 and 136. The semiconductor layer 113 is formed on the semiconductor layer 113, The gate insulating film 116 and the gate electrode 120 constitute a driving thin film transistor DTr. At this time, a switching thin film transistor (not shown) switching region (not shown) having the same structure as the driving thin film transistor DTr is formed. At this time, the switching thin film transistor (not shown) is electrically connected to the driving thin film transistor DTr, a gate wiring (not shown) and a data wiring (not shown). The data line (not shown) is connected to a source electrode (not shown) of the switching thin film transistor (not shown).

Meanwhile, the driving and switching thin film transistor DTr (not shown) forms a p-type or n-type thin film transistor according to impurities doped in the second region 113b. In the case of the p-type thin film transistor, the second region 113b is formed by doping an element of Group 3 such as boron (B). In the case of the n-type thin film transistor, For example, by doping phosphorus (P). In the p-type thin film transistor, holes are used as carriers, and n-type thin film transistors are used as carriers. The first electrode 147 connected to the drain electrode 136 of the driving thin film transistor DTr functions as an anode or a cathode electrode depending on the type of the driving thin film transistor DTr. When the driving thin film transistor DTr is p-type, the first electrode 147 serves as an anode electrode, and when the driving thin film transistor DTr is an n-type, the first electrode 147 serves as a cathode electrode. In the first embodiment of the present invention, the driving thin film transistor DTr is of the p type as an example.

A passivation layer 140 having a drain contact hole 143 exposing a drain electrode 136 of the driving thin film transistor DTr is formed on the driving and switching thin film transistor DTr (not shown). The protective layer 140 is in contact with the drain electrode 136 of the driving thin film transistor DTr through the drain contact hole 143 and has a relatively large work function value for each pixel region P, A first electrode 147 made of a material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) is formed. In this case, the first electrode 147 may have a single layer structure of only the transparent conductive material as shown in FIG. 5A, or may have a multi-layer structure as shown in FIG. 5B. The uppermost layer 147a of the multilayer structure is made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and the second layer 147b is made of aluminum And the lowermost layer 147c contacting the drain electrode 136 through the drain contact hole 143 is made of molybdenum (Mo) having excellent bonding properties for enhancing the bonding strength with the drain electrode 136, . Next, the bank 150 is formed at the boundary of each pixel region P above the first electrode 147 having a single-layer or multilayer structure as described above. At this time, the bank 150 is formed so as to overlap the rim of the first electrode 147 in a shape surrounding each pixel region P. An organic emission layer 155 is formed on the first electrode 147 in each pixel region P surrounded by the bank 150.

A second electrode 158 is formed on the entire surface of the organic light emitting layer 155 and the bank 150. At this time, the first and second electrodes 147 and 158 and the organic light emitting layer 155 formed therebetween form an organic light emitting diode E.

Although not shown in the figure, the organic light emitting layer 165 may be a single layer made of an organic light emitting material. In order to improve the light emitting efficiency, a hole injection layer, a hole transporting layer, A light emitting layer, an emitting material layer, an electron transporting layer, and an electron injection layer. At this time, the hole injecting layer, the electron injecting layer, the hole transporting layer and the electron transporting layer may be formed by mutually changing their positions. This depends on whether the first electrode 147 and the second electrode 158 serve as an anode electrode or a cathode electrode, respectively. In the first embodiment of the present invention, the first electrode 147 serves as an anode electrode. In this case, if the organic light emitting layer 155 having a multi-layer structure is formed on the first electrode 147 in the above-described order, the organic light emitting layer 155 may be sequentially stacked in the order of the hole injection layer / hole transporting layer / light emitting material layer / electron transporting layer / .

In addition, the second electrode 158 formed on the organic light emitting layer 155 having a single layer or a multilayer structure has a single layer or a double layer structure. The lower layer 158a of the single layer or the double layer of the second electrode 158 contacting the organic light emitting layer 155 may be formed of a metal material having a low work function value such as aluminum (Al), aluminum alloy, silver And the upper layer 158b located on the lower layer has a thickness of about several angstroms to several tens of angstroms. The upper layer 158b is formed of indium- Tin oxide (ITO) or indium-zinc-oxide (IZO) with a thickness of several tens to several hundreds of angstroms. At this time, the reason why the upper layer is formed is that the projection and the auxiliary electrode are formed on the second substrate in the characteristic of the present invention, and the auxiliary electrode formed to cover the projection is in contact with the second electrode, . When the second electrode is formed to have a relatively thin thickness with a single layer structure of only one of aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold (Au) There is a case where the contact property is deteriorated due to occurrence of crumbling at the time of contact, in order to prevent such a problem as a source.

The thickness of the lower layer 158a and the upper layer 158b of the second electrode 158 in the first embodiment of the present invention may be set to a general electrode formation thickness (usually about several angstroms) The second electrode 170 may be formed to have a thickness smaller than that of the second electrode (58 of FIG. 3) of the organic electroluminescent device due to the components provided on the inner surface of the second substrate 170, The configuration will be described.

On the inner surface of the second substrate 170 facing the first substrate 110, corresponding to the boundaries of the pixel regions P provided on the first substrate 110, An auxiliary electrode 178 made of any one of low resistance metal materials such as silver (Ag), aluminum (Al) and gold (Au) is formed.

At this time, a plurality of protrusions 175 having a height of about 2 탆 to 3 탆 are formed in a column shape between the auxiliary electrode 178 and the inner surface of the second substrate 170. The protrusion 175 has a tapered shape with its side surface gently inclined with respect to the inner surface of the second substrate 170 so that the auxiliary electrode 178 does not interfere with the protrusion 175 175 formed on the upper surface thereof. At this time, the protrusion 175 may be formed of an organic insulating material, for example, a photo acryl, or a polymer material such as polyimide. One or more protrusions 175 may be formed for each pixel region P and a plurality of pixel regions P may be formed as a group and may be formed in any one of the pixel regions P belonging to each group. Only one or a plurality of them may be formed.

Since the protrusion 175 is formed of an organic insulating material or a polymeric material, the bonding force between the protrusion 175 and the inner surface of the second substrate 175 may be a problem. To prevent this, For example, silicon oxide (SiO ₂ ) or silicon nitride (SiN x), or by depositing a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc- A buffer layer 173 for strengthening may be further constructed.

On the other hand, when the buffer layer 173 is formed of a transparent conductive material rather than an inorganic insulating material, the buffer layer 173 has a conductive characteristic. Since the buffer layer 173 has the same voltage on the entire surface of the second substrate 170 by making contact with the auxiliary electrode 178 Do not. Since the buffer layer 173 is made of a conductive material, even if the auxiliary electrode 178 breaks, the same voltage flows through the auxiliary electrode 178, so that the self-repair of the auxiliary electrode 178 This is an advantage in that it plays a role of making it possible.

Meanwhile, the auxiliary electrode 178 formed in the lattice shape may be a single layer structure made of the above-described low resistance metal material, or may have a double layer structure as shown in the figure. When the auxiliary electrode 178 has a double layer structure, the first layer 178a contacting the protrusion 173 may be formed of a metal material such as molybdenum (Mo), tungsten (W), or tungsten Chromium (Cr), and the second layer 178b formed to cover the first layer 178a is formed of the above-described low resistance metal material.

The first substrate 110 and the second substrate 170 are opposed to each other with an auxiliary electrode 178 formed to cover the protrusion 173, And the second electrodes 158 formed on the banks 150 of the first electrodes 110 are in contact with each other.

Accordingly, the second electrode 158 contacts the auxiliary electrode 178 formed on the second substrate 170 in a lattice form with a low-resistance metal material at various positions to receive a voltage, so that the second electrode 158 A voltage having a uniform size over the entire surface can be formed without being affected by the resistance characteristics of the metal material itself. Therefore, even if the thickness of the second electrode 158 is made thinner than the normal electrode thickness in order to improve the transparency of the second electrode 158, there is no problem of varying the voltage value by position due to the increase in internal resistance. ) Is thinned, the transmittance of the visible light can be improved.

≪ Embodiment 2 >

7 is a cross-sectional view of one pixel region P of the upper emission type organic electroluminescent device according to the second embodiment of the present invention, in which an n-type thin film transistor and a switching thin film transistor DTr (not shown) are formed Respectively. In this case, the stacked structure including the switching and driving thin film transistor DTr on the first substrate and the protective layer including the drain contact hole exposing the drain electrode of the driving thin film transistor DTr thereon is formed by the above- 1, and thus the description thereof will be omitted. The configuration of the second substrate is the same as that of the first embodiment described above, so the description of the configuration of the second substrate is also omitted. Here, reference numerals denoted by reference numerals added to the constituent elements of the first embodiment are denoted by the same reference numerals.

The top emission type organic electroluminescent device 201 according to the second embodiment of the present invention includes a first region 213b in contact with the source and drain electrodes 233 and 236 of the semiconductor layer 213, And phosphorus (P) is doped to use electrons as a carrier. The first electrode 147 that contacts the drain electrode 236 of the driving thin film transistor DTr functions as a cathode electrode and thus a work function value is formed on the protective layer 240 The first electrode 247 is formed as one of aluminum (Al), an aluminum alloy, silver (Ag), magnesium (Mg), and gold (Au) which are relatively low metal materials. At this time, the first electrode 247 may be formed to have a bilayer structure in order to improve junction characteristics with the drain electrode 236. In the case where the first electrode 247 is formed in such a bilayer structure, the lower layer 247a is formed of molybdenum (Mo) having a good junction property with the drain electrode 236, and the organic light- The upper layer 247b to be contacted is preferably formed of one of the above-described aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold (Au). In this case, the thickness of the first electrode 247 may be several thousands of angstroms, which is a typical thickness of the electrode.

In addition, the organic light emitting layer 255 located on the first electrode 247 may have a single layer structure or a multi-layer structure. When the organic light emitting layer 255 has a multi-layer structure, the organic light emitting layer 255 of the multi-layered structure may be formed on the first electrode 247 because the first electrode 247 serves as a cathode electrode, Electron transport layer / luminescent material layer / hole transport layer / hole injection layer from the surface of the hole injection layer 247 in this order.

Further, a second electrode 258 is formed on the entire surface of the organic light emitting layer 255 having the single-layer or multi-layer structure. Since the second electrode 258 serves as an anode electrode, the second electrode 258 is formed of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), which is a transparent conductive material having a relatively high work function, Is formed to have a thickness in the range of several hundreds of angstroms, which is thinner than the thickness of the substrate. In this case, the second electrode 258 has its internal resistance increased by thinning the second electrode 258, so that the second electrode 258 may have a large voltage difference depending on positions. However, due to the characteristics of the present invention, 2 auxiliary electrode 278 provided on the substrate 270 to receive a voltage, so that generation of a voltage difference by position due to an increase in internal resistance is suppressed.

Other components are the same as those of the first embodiment described above, and a description thereof will be omitted.

FIG. 8 is a cross-sectional view of one pixel region of a top emission type organic electroluminescent device according to a modification of the second embodiment of the present invention, showing an n-type thin film transistor including an amorphous silicon semiconductor layer. In this case, reference numerals are added to the same components as those of the first embodiment by adding 200.

There is a difference in the layer in which the second embodiment and the switching and driving thin film transistor (not shown) are formed and the layer in which power supply wiring (not shown), gate and data wiring (not shown) are formed, (Not shown), the structure of a switching and driving thin film transistor (not shown) and the formation of a power wiring (not shown), a gate and a data wiring (not shown) 330 will be described.

As shown in the drawing, the pixel region P is defined on the first substrate 310 so as to intersect with each other, and gate and data lines (not shown) are formed so as to intersect with each other. Wiring (not shown) is formed. In addition, switching thin film transistors (not shown) are formed at the intersections of the gate and data lines (not shown). A driving thin film transistor DTr, which is electrically connected to the switching thin film transistor (not shown) and has the same structure as the switching thin film transistor (not shown), is formed.

A gate electrode 320 is formed on the first substrate 310 and a gate insulating layer 321 is formed on the gate electrode 320. The gate electrode 320 is formed on the first substrate 310, have. A semiconductor layer 322 composed of an amorphous silicon active layer 322a and an ohmic contact layer 322b of impurity amorphous silicon are formed on the gate insulating layer 321 in correspondence with the gate electrode 320, Respectively. Source and drain electrodes 333 and 336 are formed on the ohmic contact layer 322b. At this time, the source and drain electrodes 333 and 336 spaced apart from the gate electrode 320, the gate insulating film 321, and the semiconductor layer 322 which are sequentially stacked form a driving thin film transistor DTr. Though not shown, a switching thin film transistor (not shown) having the same structure as the driving thin film transistor DTr is formed in a switching region (not shown). A gate wiring (not shown) extends in one direction and is connected to a gate electrode (not shown) of the switching thin film transistor (not shown). The gate wiring (not shown) (Not shown), and a data line 330 is formed to connect with a source electrode (not shown) of the switching thin film transistor (not shown).

 A protective layer 340 having a drain contact hole 343 exposing the drain electrode 336 of the driving thin film transistor DTr is formed on a switching and driving thin film transistor (not shown) having the above-described structure . The structure of the second substrate 370 including the organic electroluminescent diode E formed on the passivation layer 340 is the same as that of the second embodiment described above.

<Manufacturing Method>

Hereinafter, a method of manufacturing the top emission type organic electroluminescent device according to the first embodiment described above with reference to FIGS. 5A and 5B will be briefly described. In the case of the second embodiment, only the material having the first electrode, the material constituting the first electrode and the second electrode, and the structure thereof are different from each other, so that only the constitution having the difference is briefly mentioned.

First, a method of manufacturing the first substrate 110 will be described. Amorphous silicon is deposited on the insulating substrate 110 to form an amorphous silicon layer (not shown), and the amorphous silicon layer is crystallized into a polysilicon layer (not shown) by irradiating a laser beam or by heat treatment . Thereafter, a mask process is performed to pattern the polysilicon layer (not shown) to form a semiconductor layer 113 in a pure polysilicon state. A first buffer layer (not shown) may be formed by depositing an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN x) on the entire surface of the insulating substrate before forming the amorphous silicon layer have.

Next, silicon oxide (SiO ₂ ) is deposited on the semiconductor layer 113 of pure polysilicon to form a gate insulating film 116. A first metal layer (not shown) is deposited on the gate insulating layer 116 by depositing a metal material such as aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, And a mask process is performed to form a gate electrode 120 corresponding to a central portion of the semiconductor layer 113. At this time, gate wirings (not shown) connected to a gate electrode (not shown) formed in a switching region (not shown) of the gate electrode 120 and extending in one direction are also formed.

Next, an impurity, that is, a trivalent element or a pentavalent element is doped on the entire surface of the substrate 110 using the gate electrode 120 as a blocking mask, thereby forming a semiconductor layer 113 located outside the gate electrode 120 The second region 113b doped with the impurity and the portion corresponding to the doped gate electrode 120 form a first region 113a of pure polysilicon.

Next, an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiO ₂ ) is deposited on the entire surface of the substrate 110 on which the semiconductor layer 113 is formed by dividing the first and second regions 113a and 113b, The second interlayer insulating film 123 and the lower gate insulating film 116 are simultaneously or collectively patterned so as to expose the second region 113b, (125).

Thereafter, a metal material such as aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, chromium (Cr), and molybdenum (Mo) is deposited on the interlayer insulating layer 123, And source and drain electrodes 133 and 136 which are in contact with the second region 113b are formed through the semiconductor layer contact hole 125 by patterning the mask layer. A data line 130 connected to a source electrode (not shown) formed in the switching region (not shown) on the interlayer insulating layer 123 and intersecting the gate line (not shown) to define a pixel region P (Not shown) spaced apart from the data line 130 and arranged side by side. At this time, the source and drain electrodes 133 and 136, which are separated from the semiconductor layer 113, the gate insulating film 116, the gate electrode 120, and the interlayer insulating film 123, constitute a driving thin film transistor DTr. At this time, a switching thin film transistor (not shown) having the same structure as the driving thin film transistor DTr is formed in the switching region.

Next, the source and drain electrodes, for (133, 136) over the inorganic insulating material, for example silicon oxide (SiO ₂₎ or silicon nitride deposition, or an organic insulating material, the (SiNx), for example, photo acryl (photo acryl) or benzo cyclo A passivation layer 140 is formed by applying butene (BCB) and patterned to form a drain contact hole 143 exposing the drain electrode 136 of the driving TFT DTr.

In the case of the first embodiment, a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) having a relatively high work function value is formed to have a thickness of several thousand angstroms A first electrode 147 having a single layer structure is formed (see FIG. 5A), which is in contact with the drain electrode 136 of the driving thin film transistor DTr through the drain contact hole 143 by depositing and patterning. Or molybdenum (Mo) is deposited on the protective layer 140 to have a thickness of about 100 Å to about 200 Å and aluminum (Al) having excellent reflectivity is deposited to have a thickness of about 500 Å to 1500 Å. Finally, indium- A ternary metal layer (not shown) is formed by depositing tin oxide (ITO) or indium-zinc-oxide (IZO) to a thickness of about 500 Å to 1500 Å. Thereafter, the triple-layer structure 147 (147a, 147b, 147c) is formed (see FIG. 5B) by patterning the triple metal layer (not shown) through a mask process.

Thereafter, an organic insulating material such as photo acryl or benzocyclobutene (BCB) is deposited on the first electrode 147 and patterned to form a bank 150 to frame each pixel region P do.

Next, an organic light emitting material 155 is formed on the first electrode 147 exposed to the substrate 110 on which the bank 150 is formed by thermal evaporation using a shadow mask (not shown) .

Next, one of aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold (Au) is thermally deposited on the organic light emitting layer 155 to form a relatively thin Or a lower layer 158a made of any one of aluminum (Al), aluminum alloy, silver (Ag), magnesium (Mg), and gold (Au) A transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) is deposited to a thickness of about 50 Å to 200 Å to reinforce the mechanical strength upon contact with the auxiliary electrode 178 of the substrate 170 The second electrode 158 (158a, 158b) having a two-layer structure is formed by depositing the first electrode 158a and the second electrode 158b so as to have an upper layer 158b.

On the other hand, in the case of the second embodiment, since the method of manufacturing the first substrate according to the first embodiment described above is different from that of forming the first electrode and the second electrode, Only a method of forming the electrode will be described briefly.

In the second embodiment, the first electrode 247 serves as a cathode electrode. Therefore, a metal having a low work function value such as aluminum (Al), aluminum alloy, silver (Ag), magnesium The first electrode 247 having a single layer structure which contacts the drain electrode 236 of the driving thin film transistor DTr through the drain contact hole 243 by depositing and patterning one of Mg, Molybdenum (Mo) is deposited to a thickness of 50 to 150 Å to form a lower layer 247a to improve the bonding property with the drain electrode 236. Aluminum (Al), an aluminum alloy, silver The upper layer 247b is formed by depositing one of Ag, Mg, and Au and then simultaneously or collectively patterning the upper layer 247b and the lower layer 247a to form a first Electrodes 247 (247a, 247b) can be formed.

The second electrode 258 may be formed of a transparent conductive material having a high work function value such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) For example.

5A and 5B, the second substrate 170 facing the first substrate 110 having the above-described configuration is formed on the transparent substrate 170 with an inorganic insulating material such as silicon oxide SiO ₂₎ or silicon nitride (SiNx) deposition, or, for a transparent conductive material, for example indium-tin-form the oxide (second buffer layer (173 in the front by depositing an IZO)) - oxide (ITO) or indium-zinc . In this case, the second buffer layer 173 may be omitted for improving the bonding strength between the protrusions 175 to be formed later and the second substrate 170.

Next, a photo acryl or a polyimide, which is an organic insulating material, or a polyimide is applied on the second buffer layer 173 and patterned to form pixel regions P of the first substrate 110, The protrusions 175 having a columnar shape and a height of 2 탆 to 3 탆 are formed.

Next, a metal material such as silver (Ag), aluminum (Al), or gold (Au) having low resistance and reflection characteristics is deposited on the entire surface of the protrusion 175 and patterned, (Not shown) having a single layer structure that completely covers the protrusions 175 in the form of a lattice that frames each pixel region P along the boundary. At this time, the auxiliary electrode 178 may have a double-layer structure as shown in the figure. In this case, a first layer (not shown) is formed by depositing a metal material selected from molybdenum (Mo), tungsten (W) and chromium (Cr) on the entire surface of the protrusion 175, A second layer (not shown) is formed by depositing one of silver (Ag), aluminum (Al), and gold (Au), which are metal materials, Layered auxiliary electrodes 178 (178a, 178b) having a lattice shape by simultaneously or collectively patterning the auxiliary electrodes 178a, 178b.

The first substrate 110 and the second substrate 170 are positioned so that the auxiliary electrode 178 and the second electrode 158 face each other and the edges of the two substrates 110 and 170 Thereby forming a seal pattern (not shown). Then, the auxiliary electrode 178 located on the projection 175 and the second electrode 158 located on the bank 150 are brought into contact with each other. Thereafter, in the atmosphere of inert gas or vacuum, 110, and 170 may be joined together to complete the top emission type organic electroluminescent device 101 according to the first embodiment of the present invention.

Meanwhile, in the modification of the second embodiment, only the structure of the driving and switching thin film transistors is different from that of the second embodiment, so that the method of manufacturing the driving and switching thin film transistors will be briefly described with reference to FIG.

A gate wiring (not shown) extending in one direction is formed on the insulating substrate 310 by depositing a metal material such as aluminum (Al), an aluminum alloy (AlNd), copper (Cu), a copper alloy and chromium And at the same time, the gate electrode 320 is formed in the switching region and the driving region (not shown). At this time, a gate electrode (not shown) formed in the switching region (not shown) is connected to the gate wiring (not shown).

Next, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN x) is deposited on the gate wiring (not shown) and the gate electrode 320 to form a gate insulating film 321. Then, an impurity amorphous silicon pattern (not shown) made of an impurity amorphous silicon is formed on the active layer 322a of pure amorphous silicon corresponding to each gate electrode 320 on the gate insulating film 321. Then,

Next, a data line (not shown) which intersects the gate line (not shown) and defines the pixel region P over the gate insulating layer 321 by depositing a metal material on the entire surface of the impurity amorphous silicon pattern And source and drain electrodes 333 and 336 spaced apart from each other are formed on the impurity amorphous silicon pattern (not shown). At this time, a source electrode (not shown) formed in the switching region (not shown) is connected to the data line 330.

Next, the impurity amorphous silicon pattern (not shown) exposed between the source and drain electrodes 333 and 336 is removed to form the ohmic contact layer 322b. At this time, the gate electrode 320, the gate insulating film 321, the semiconductor layer 322 composed of the active layer 322a and the ohmic contact layer 322b, and the source and drain electrodes 333 and 336 spaced from each other Thereby forming a driving thin film transistor DTr. A switching thin film transistor (not shown) having the same structure as that of the driving thin film transistor DTr is formed even in switching (not shown).

Next, a protective layer 340 having a drain contact hole 343 exposing the drain electrode 336 of the driving thin film transistor DTr is formed on the driving and switching thin film transistor DTr (not shown) formed as described above And then the organic light emitting diode E is formed on the passivation layer 340 as in the second embodiment described above to complete the first substrate 310 according to the modification of the second embodiment .

1 is a circuit diagram of a pixel of a general active matrix organic electroluminescent device.

2 is a schematic cross-sectional view of a conventional top emission type organic electroluminescence device.

FIG. 3 is a cross-sectional view of one pixel region including the driving thin film transistor of the top emission type organic electroluminescent device shown in FIG. 2; FIG.

4A and 4B are enlarged views of region A in Fig. 3; Fig.

FIGS. 5A and 5B are cross-sectional views illustrating a part of a top emission type organic electroluminescent device according to a first embodiment of the present invention, which includes a driving thin film transistor and an organic light emitting diode. FIG.

6 is a plan view showing a part of a second substrate in a top emission type organic electroluminescent device according to the first embodiment of the present invention.

7 is a sectional view of one pixel region of a top emission type organic electroluminescent device according to a second embodiment of the present invention.

8 is a cross-sectional view of one pixel region of a top emission type organic electroluminescent device according to a modification of the second embodiment of the present invention.

Description of the Related Art

101: top emission type organic electroluminescent device

110: first substrate 113: semiconductor layer

113a and 113b: first and second regions 116: gate insulating film

120: gate electrode 123: interlayer insulating film

125: semiconductor layer contact hole 130: data line

133: source electrode 136: drain electrode

140: protective layer 143: drain contact hole

147: first electrode 150: bank

155: organic light emitting layer 158: second electrode

158a: (second electrode) lower layer 158b: (second electrode) upper layer

170: second electrode 173: second buffer layer

175: projection 178: auxiliary electrode

178a, 178b: (auxiliary electrode) First layer and second layer

DA: driving region P: pixel region

Claims (13)

A first substrate on which a pixel region is defined; A switching thin film transistor and a driving thin film transistor on the first substrate; A first electrode contacting the drain electrode of the driving thin film transistor; An organic light emitting layer on the first electrode; A second electrode on the organic light emitting layer; A second substrate facing the first substrate; A protrusion disposed on an inner surface of the second substrate; A buffer layer made of indium-tin-oxide (ITO) or indium-zinc-oxite (IZO) is formed between the second substrate and the protrusion. And the organic electroluminescent device. The method according to claim 1, A first layer made of a first metal material covering the protrusion and contacting a boundary of the pixel region and contacting the second electrode; and a second layer made of a second metal material and positioned between the second substrate and the first layer Layer structure of the organic electroluminescent device according to the present invention. 3. The method of claim 2, Wherein the first metal material is one of silver (Ag), aluminum (Al), and gold (Au) Wherein the second metal material is one of molybdenum (Mo), tungsten (W), and chromium (Cr). 3. The method of claim 2, Wherein the protrusions are made of photo acryl or polyimide. The method according to claim 1, Wherein the switching and driving thin film transistor is a p-type thin film transistor, and the first electrode is an anode electrode. 6. The method of claim 5, The first electrode may have a single layer structure made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), or may be made of a molybdenum (Mo) Layer structure composed of a first layer made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) and a third layer made in contact with the organic light- And the upper emission type organic electroluminescence element. 3. The method of claim 2, The second electrode may have a single layer structure of one of aluminum (Al), silver (Ag), magnesium (Mg), and gold (Au) as a third metal material or may be formed of the third metal material Layer structure of a second layer made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) in contact with the auxiliary electrode and a first layer in contact with the organic light emitting layer. 8. The method of claim 7, Wherein the second electrode of the single layer structure of the third metal material and the first layer of the second electrode of the double layer structure have a thickness of 5 to 50 Angstroms. The method according to claim 1, Wherein the switching and driving thin film transistor is an n-type thin film transistor, and the first electrode is a cathode electrode. 10. The method of claim 9, The first electrode may have a single layer structure of one of aluminum (Al), silver (Ag), magnesium (Mg), and gold (Au) Layer structure composed of a first layer made of molybdenum (Mo) and a second layer made of the third metal material and in contact with the organic light-emitting layer. 10. The method of claim 9, Wherein the second electrode has a single layer structure of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). delete The method according to claim 1, A gate wiring and a data wiring crossing each other and defining the pixel region and a power wiring line disposed in parallel with the data wiring are disposed on the first substrate, the gate and the data wiring are respectively connected to the gate electrode of the switching thin- And the source electrode is connected to the upper emission type organic electroluminescence device.

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