KR101781049B1 - Organic electro-luminescent Device - Google Patents

Abstract

The present invention provides a display device comprising: a first substrate on which a display region having a plurality of pixel regions is defined; A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 lower layer of a first thickness made of a metal material having a low work function value and an upper layer having a second thickness of a transparent conductive oxide and formed on the entire surface of the display region over the organic light emitting layer and the bank, And an organic electroluminescent device.

Description

[0001] The present invention relates to an 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 which improves the transmittance of a cathode electrode while maintaining a low resistance characteristic in a top emission type structure.

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 V 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.

Accordingly, the organic electroluminescent device having the above-described advantages has recently been used in various IT devices such as a TV, a monitor, and a mobile phone.

Hereinafter, the basic structure of the organic electroluminescent device will be described in more detail.

BACKGROUND ART An organic electroluminescent device is largely composed of an array element and an organic electroluminescent diode. The array element includes a switching thin film transistor connected to a gate and a data line, and a driving thin film transistor connected to the organic light emitting diode. The organic light emitting diode includes a first electrode connected to the driving thin film transistor, Electrode.

In the organic electroluminescent device having such a configuration, light emitted from the organic light emitting layer is emitted toward the first electrode or the second electrode to display an image. Such an organic electroluminescent device is generally manufactured by a top emission type in which an image is displayed using light emitted toward the second electrode in consideration of an aperture ratio and the like.

However, due to the manufacturing characteristics of the organic electroluminescent device, the second electrode located above the organic luminescent layer can not be formed by sputtering, which is a general metal material evaporation method, to prevent damage to the organic luminescent layer. .

The first electrode is made of indium-tin-oxide (ITO), which is a transparent conductive material having a high work function value, to serve as an anode electrode. The second electrode has a low work function value And is made of a metal material.

However, since the metal material having a low work function value constituting the second electrode serving as the cathode electrode has opaque characteristics, if the opaque metal is formed to have a thickness of about 1000 to 4000 ANGSTROM Light can not penetrate.

Therefore, the second electrode made of an opaque metal material having a low work function value is formed to have a thickness of about 10 Å to about 200 Å to form a lower layer made of an opaque metal material in order to ensure transparency. In this case, since the light transmittance of the second electrode is 15% or more, the brightness level of a general display device is obtained.

 However, if the second electrode is formed to have a thickness of about 10 Å to 200 Å, the sheet resistance becomes 20 Ω / □ to 1000 Ω / □. In this case, since the resistance of the second electrode itself is high, , Which causes fast battery consumption particularly when applied to personal portable IT devices.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a top emission type organic electroluminescent device capable of improving the light transmittance without increasing the resistance of the second electrode of the organic electroluminescent diode formed in the uppermost layer. And an organic electroluminescent device comprising the same.

According to an aspect of the present invention, there is provided an organic electroluminescent device including a first substrate on which a display region having a plurality of pixel regions is defined; A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 entire surface of the display region on the organic light emitting layer and the bank, the second electrode having a first layer having a first thickness and the second layer having a second thickness made of a transparent conductive oxide, .

In this case, the transparent conductive oxide is indium-zinc-oxide (IZO) or indium-tin-oxide (ITO).

According to another aspect of the present invention, there is provided an organic electroluminescent device comprising: a first substrate having a display region defined therein having a plurality of pixel regions; A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 on the entire surface of the display region above the bank, the first electrode having a single layer structure of a magnesium-silver alloy; And a transparent insulating layer formed on the entire surface of the display region in contact with the second electrode.

At this time, the transparent insulating film is formed of silicon oxide (SiO ₂ ) or aluminum oxide (Al ₂ O ₃ ), which is an inorganic insulating material, or a polymer or monomer, which is an organic insulating material.

In addition, the switching and driving thin film transistor is a p-type thin film transistor, the first electrode serves as an anode electrode, and the second electrode serves as a cathode electrode.

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 high work function value, A first layer made of any one of aluminum (Al), an aluminum alloy (AlNd), and silver (Ag) which is in contact with an electrode and has excellent reflectivity and a second layer made of the transparent conductive material and in contact with the organic light- Layer structure constituted by a single layer structure.

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 Electrode and the source electrode.

According to another aspect of the present invention, there is provided an organic electroluminescent device comprising: a first substrate having a display region defined therein having a plurality of pixel regions; A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 first layer of a first thickness made of a first metal and a first transparent conductive layer made of a transparent conductive oxide and a low resistance metal layer made of a low resistance metal material, And a second transparent conductive layer formed of a transparent conductive oxide and a second electrode formed on the first layer and having a structure of the first layer and the first set layer.

At this time, the second electrode has a sheet resistance of 1.9? /? To 5? / ?.

The second electrode may be formed of the first layer, the first set layer, and the second set layer by forming another set layer on the first set layer, wherein the second electrode has a sheet resistance of 1 Ω / □ to 2 Ω / □.

Wherein the first layer is made of any one of silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg), copper (Cu), and calcium (Ca) (ITO) or indium-zinc-oxide (IZO), and the low-resistance metal layer is formed of any one of silver (Ag), gold (Au), and copper (Cu).

Wherein the first and second set layers each have a thickness of about 10 A to 50 A and the first and second set layers each have a thickness of about 400 A to about 1000 A, And has a thickness of 150 ANGSTROM to 300 ANGSTROM.

According to another aspect of the present invention, there is provided an organic electroluminescent device comprising: a first substrate having a display region defined therein having a plurality of pixel regions; A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 in the bank and emitting red, green, and blue light for each pixel region; A first layer made of a first metal, a second layer made of a transparent conductive oxide, a third layer made of a low-resistance metal material, and a second layer made of a transparent conductive material, A fourth layer made of an oxide or an organic material, a fifth layer made of the low-resistance metal material, and a sixth layer made of the transparent conductive oxide, the fourth layer having a six- The organic light emitting layer emitting red, green, and blue light is formed with different thicknesses for each pixel region.

At this time, the fourth layer has a thickness of 600 ANGSTROM to 1200 ANGSTROM, the portion overlapping the organic light emitting layer emitting blue light has the thinnest thickness, and the portion overlapping the organic light emitting layer emitting red light has the largest thickness .

The first layer has a thickness of 10A to 50A and the third and fifth layers of the low resistance metal material have a thickness of 150A to 400A.

The first layer may be formed of any one of silver (Ag), magnesium-silver alloy (Ag), gold (Au), magnesium (Mg), copper (Cu), and calcium (Ca) Wherein the oxide is indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), the organic material is any one of photoacryl, benzocyclobutene or the material forming the organic light emitting layer, Wherein the first electrode is made of at least one of Ag, Au and Cu, and the second electrode has a sheet resistance of 1? /? To 3? / ?.

When the fourth layer is made of the organic material, the fourth layer is formed apart from the boundaries of the pixel regions, and the third layer and the fifth layer are made to contact each other at the boundaries of the pixel regions .

Wherein the switching and driving thin film transistor is a p-type thin film transistor, the first electrode serves as an anode electrode, and the second electrode serves as a cathode electrode. The first electrode has a work function value Layer structure of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), which is a high transparent conductive material, or aluminum Layer structure composed of a first layer made of any one of aluminum (Al), aluminum alloy (AlNd) and silver (Ag), and a second layer made of the transparent conductive material and in contact with the organic light emitting layer.

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 Electrode and the source electrode.

In addition, the second substrate is opposed to the first substrate and has a transparent second substrate for encapsulation.

At this time, the second substrate is formed in contact with the second electrode and has a multilayer structure in which the inorganic film and the organic film alternate.

The second substrate may have a four-layer structure of organic film / inorganic film / organic film / inorganic film.

In addition, the second substrate may have a five-layer structure of an inorganic film / an organic film / an inorganic film / an organic film / an inorganic film, and the second electrode contacting the second substrate may be formed by omitting the uppermost layer made of a transparent conductive oxide, 2 substrate is in contact with the layer made of the low-resistance material of the second electrode.

At this time, the inorganic film is made of any one of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ) and silicon nitride (SiNx), and the organic film is composed of a monomer or a polymer.

The top emission type organic electroluminescent device according to the present invention includes a metal layer having a low work function value and a metal layer having a thickness of about 10 to 200 angstroms and a transparent layer made of a transparent conductive material or a conductive material layer of transparent metal oxide Or by forming a metal layer having a thickness of about 10 to 200 angstroms with a metal material having a low work function value and an organic insulating material layer thereon to form a surface plasmon phenomenon so that the sheet resistance is 10? And at the same time, the light transmittance is improved.

1 is a circuit diagram of one pixel of a general organic light emitting device.
2 is a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a first embodiment of the present invention.
3 is a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a modification of the first embodiment of the present invention.
FIG. 4 is a cross-sectional view of a first embodiment of the present invention in which the second electrode has a double-layer structure of a magnesium-silver alloy and a transparent conductive oxide, and FIG. FIG. 2 is a graph showing transmittance of an organic electroluminescent device according to a modified example of the first embodiment of the present invention and a second electrode of a magnesium-silver alloy single layer structure according to wavelengths of an organic electroluminescent device according to a comparative example. FIG.
5 is a sectional view of one pixel region of an organic electroluminescent device according to a second embodiment of the present invention.
FIG. 6 is a graph showing the transmittance of a second embodiment of the present invention in which the second electrode has a quadruple layer structure, and a transmittance of an organic electroluminescent device according to a comparative example in which the second electrode has a magnesium-silver alloy single layer structure.
7 is a sectional view of one pixel region of an organic electroluminescent device according to a third embodiment of the present invention.
8 shows a third embodiment of the present invention having a second electrode having a six layer of IZO / Ag / IZO / IZO / Ag / IZO over a first layer of a magnesium-silver alloy (Mg: Ag) Ag / IZO / Ag and IZO / Ag / IZO / Ag (IZO) and the first comparative example having a layer made of Ag on the first layer of magnesium-silver alloy / IZO according to the second comparative example having the second electrode provided with the five-layered structure of the organic electroluminescent device.
9 is a cross-sectional view of three pixel regions which emit successive red, green, and blue light, respectively, of an organic electroluminescent device according to a fourth embodiment of the present invention.
10 is a graph showing transmittance of a fourth electrode of a second electrode of an organic electroluminescent device according to a fourth embodiment of the present invention, in which the thickness of the fourth electrode is changed to 600 ANGSTROM to 1000 ANGSTROM.
11 is a cross-sectional view of three pixel regions that emit successive red, green, and blue light, respectively, of an organic electroluminescent device according to a fifth embodiment of the present invention.
FIG. 12 is a graph showing transmittance of a fourth electrode of a second electrode of an organic electroluminescent device according to a fifth embodiment of the present invention, in which the thickness of the fourth electrode is changed to 800 ANGSTROM to 1200 ANGSTROM. FIG.
13 is a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a sixth embodiment of the present invention.
14 is a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a modification of the sixth embodiment of the present invention.

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

First, the structure and operation of an organic electroluminescent device will be briefly described with reference to Fig. 1, which is a circuit diagram for one pixel of an organic electroluminescent device.

As shown, a switching thin film transistor STr, a driving thin film transistor DTr, a storage capacitor StgC, and an organic light emitting diode E are provided in one pixel of the organic electroluminescent device have.

That is, a gate line GL is formed in a first direction, a data line DL is defined by defining a pixel region P in a second direction intersecting the first direction, and the data line DL And 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 electroluminescent diode E, is connected to the drain electrode of the driving thin film transistor DTr, and the second electrode, which is the other terminal, is grounded. 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, the level of a current flowing from the power supply line PL to the organic light emitting diode E is determined, 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.

2 is a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a first embodiment of the present invention. In this case, for convenience of description, a region where the driving thin film transistor DTr is formed is referred to as a driving region DA, and a region where a switching thin film transistor is formed in each pixel region P (not shown) .

The organic EL device 101 according to the first embodiment of the present invention includes a first substrate 110 on which a driving and switching thin film transistor DTr and an organic light emitting diode E are formed, And a second substrate 170 for encapsulation. At this time, the second substrate 170 may be omitted by being replaced with an inorganic film, an organic film, or the like.

First, the structure of the first substrate 110 including the driving and switching thin film transistor DTr (not shown) and the organic electroluminescent diode E will be described.

The driving region DA and the switching region on the first substrate 110 are respectively made of pure polysilicon and the central portion of the driving region DA has a first region 113a and a second region 113b. A semiconductor layer 113 composed of a second region 113b doped with a high concentration of impurities is formed.

At this time, a buffer layer (not shown) made of an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) is further provided on the entire surface between the semiconductor layer 113 and the first substrate 110 It is possible. 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. A gate insulating layer 116 is formed on the semiconductor layer 113 The gate electrode 120 is formed in correspondence with the first region 113a of the gate electrode 120a. 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).

Next, an interlayer insulating film 123 made of an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) is formed on the gate electrode 120 and the gate wiring (not shown). A semiconductor layer contact hole 125 exposing the second region 113b located on both sides of the first region 113a is formed in the interlayer insulating layer 123 and the gate insulating layer 116 below the interlayer insulating layer 123 .

Next, a data line (not shown) is formed on the interlayer insulating layer 123 provided with the semiconductor layer contact hole 125 to define a pixel region P intersecting the gate line (not shown) A power supply wiring (not shown) is formed side by side.

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.

On the other hand, 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 sequentially stacked in the driving region DA, Thereby forming 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 formed in the driving region DA is formed in the switching region (not shown).

The switching thin film transistor (not shown) is electrically connected to a gate wiring (not shown) and a data wiring (not shown), and further to the driving thin film transistor DTr.

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.

That is, 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 p-type, so that the first electrode 147 serves as an anode electrode.

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). At this time, the protective layer 140 is formed of an organic insulating material such as photo acryl or benzocyclobutene (BCB) so as to obtain a flat surface without being affected by the step of the lower component .

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. The pixel electrode P has a transparent conductive layer A first electrode 147 made of a material such as indium-tin-oxide (ITO) is formed.

The first electrode 147 may have a single layer structure made only of the above-described transparent conductive material, or may be made of aluminum (Al), which is a metal material having a high reflectivity for increasing the luminous efficiency of the upper part of the organic light emitting diode E. Layer structure of a first layer 147a made of Al, an aluminum alloy (AlNd) or silver (Ag) and a second layer 147b made of a metal material having a high work function value.

Next, as described above, the first electrode 147 having a single-layer structure or a double-layer structure and overlapping the edge of the first electrode 147 serving as an anode electrode, and the bank 150 Is formed.

An organic light emitting layer 155 is formed on the first electrode 147 in each pixel region P surrounded by the bank 150. The organic light emitting layer 155 may be formed of a single layer made of an organic light emitting material or may be sequentially formed from the top of the first electrode 147 serving as the anode electrode, a hole injection layer 155a, a hole transporting layer 155b, an emitting material layer 155c, an electron transporting layer 155d, and an electron injection layer 155d. layer 155e. In the drawing, for example, the organic light emitting layer 155 has a five-layer structure.

Next, in the first embodiment of the present invention, the organic light emitting layer 155 and the bank 150 serve as a cathode electrode on the entire surface of the display region, and a second electrode 158 are formed. 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).

The lower layer of the second electrode 158 having a bilayer structure may be formed of a metal material having a low work function value such as silver (Ag), a magnesium-silver alloy (Mg), a gold (Au) ), Magnesium (Mg), copper (Cu), and calcium (Ca), and has a thickness of about 50 Å to about 200 Å in order to maintain the light transmittance at 15% to be.

An upper layer of the second electrode 158 is formed of indium-zinc-oxide (IZO) or indium-tin-oxide (ITO) which is a transparent conductive material and has a thickness of about 50 Å to 1000 Å .

The second electrode 158 having such a bilayer structure is formed such that the lower layer made of a metal material having a low work function value has a thickness of about 10 to 200 angstroms and its sheet resistance is increased. An upper layer made of a transparent conductive material The thickness of the second electrode 158 itself increases as the thickness of the second electrode 158 is about 50 Å to 1000 Å, thereby reducing the sheet resistance.

Table 1 shows an organic electroluminescent device in which a second electrode having a single layer structure of magnesium-silver alloy (Mg: Ag) is formed as a comparative example and a second electrode having a double- And the transmittance of light of a specific wavelength band in a state where the second electrode of the electroluminescent device has a similar level of sheet resistance.

Single layer (MgAg) Double layer (MgAg + IZO) Sheet resistance (Ω / □) 9.9 (Ω / □) 10.5 (Ω / □) Permeability (%) Light of 470nm wavelength 15.8% 42.6% 550nm wavelength light 11.9% 32.5% 630nm wavelength light 9.2% 22%

Referring to Table 1, in the organic electroluminescent device according to the comparative example and the first embodiment of the present invention, when the sheet resistance of the second electrode is adjusted to a similar level that can operate as an organic electroluminescent device, In the comparative example having a single layer structure of a magnesium-silver alloy (Mg: Ag), the respective transmittances for light having wavelength bands of 470 nm, 550 nm and 630 nm were 15.8%, 11.9% and 9.2%, respectively, For the first embodiment of the present invention having a bilayer structure of a lower layer of silver (Mg: Ag) and an upper layer of indium-zinc-oxide (IZO), the respective transmittances for light having wavelength bands of 470 nm, 550 nm and 630 nm 42.3%, 32.5% and 22%, respectively, it can be seen that the luminance characteristic of the first embodiment according to the present invention is improved by two times or more as compared with the comparative example.

Table 2 shows an organic electroluminescent device in which a second electrode having a single layer structure of magnesium-silver alloy (Mg: Ag) is formed as a comparative example and a second electrode having a double- In the electroluminescent device, the light transmittance at each wavelength band when the portion made of magnesium-silver alloy (Mg: Ag) has the same thickness.

Permeability (%) Single layer (MgAg) Double layer (MgAg + IZO) Light of 470nm wavelength 10.5% 26.1% 550nm wavelength light 7.9% 18.4% 630nm wavelength light 6.3% 12.4%

Referring to Table 2, in the organic EL device according to the comparative example and the first embodiment of the present invention, the light transmittance of each wavelength band when the portions made of the magnesium-silver alloy (Mg: Ag) In the comparative example in which the second electrode has a single layer structure of a magnesium-silver alloy (Mg: Ag), the respective transmittances of light having wavelengths of 470 nm, 550 nm, and 630 nm are 10.5%, 7.9%, and 6.3% While the second electrode has a wavelength band of 470 nm, 550 nm and 630 nm in the case of the first embodiment of the present invention having a dual layer structure of a lower layer of magnesium-silver alloy (Mg: Ag) and an upper layer of indium-zinc-oxide The transmittance of each light is 26.1%, 18.4% and 12.4%, respectively.

Accordingly, even though the second electrode made of magnesium-silver alloy (Mg: Ag) having the same thickness is formed, the organic electroluminescent device according to the present invention having a structure in which an upper layer made of indium-zinc- It is found that the transmittance is improved more than two times.

The improvement in the transmittance of the bilayer structure of the different materials rather than the single layer structure is due to the microcavity effect due to the optical length control.

The microcurve effect is that the light repeats reflection inside a specific material layer. When the specific condition is satisfied, the light is reflected at a time to improve the light transmission efficiency. In order to realize such microcubitic effect, .

3 (a cross-sectional view of a portion of a display region of an organic electroluminescent device according to a modification of the first embodiment of the present invention as a modification of the first embodiment) The second electrode 158 is formed of a metal material having a low work function value such as silver (Ag), a magnesium-silver alloy (Mg), a gold (Au) (SiO 2) or aluminum oxide (Al ₂ O ₃ ) is formed on the second electrode 158 having a single-layer structure on the upper surface of the second electrode 158. In this case, An insulating film 162 is formed, or an organic insulating film (not shown) made of a transparent organic material such as a polymer or a monomer is formed.

The organic electroluminescent device 101 according to a modification of the present invention having such a structure also has a structure in which a second electrode 158 having a conventional single layer structure is formed and an inorganic insulating film or an organic insulating film is not formed on the second electrode 158 The light transmission characteristic of the organic electroluminescent device according to the present invention is improved.

In the case of the organic EL device 101 according to the modification described above, although the second electrode 158 is formed with a single layer structure of gold (Au) and silver (Ag) as an example of a metal material having a low work function value However, a transparent inorganic insulating film 162 or an organic insulating film (not shown) is formed in contact with the second electrode 158 of the single layer on the transparent insulating film 162. Surface plasmons are generated by this configuration, The transmittance of light generated from the light emitting layer 155 can be improved.

Surface plasmons are collective charge density oscillations of electrons occurring on the surface of metal thin films. These surface plasmons are generated by metals that have a negative dielectric constant, The metal that generates surface plasmons is, for example, gold (Au), silver (Ag), or the like.

The plasmons act as a group when light enters from the outside, and when the light satisfying a specific condition is incident, the plasmon emits a stronger light in response to the incident light. It is known that the transmittance of light is improved by the characteristics of the surface plasmon there was.

Meanwhile, in the case of the organic EL device 101 according to the modification of the first embodiment of the present invention, the second electrode 158 having a single layer structure of a metal material having a low work function value has low resistance The transmittance of the second electrode 158 may be made thicker than that of the comparative example so that the transmittance of the second electrode 158 may be made thicker than that of the comparative example, Can be lowered. Therefore, in the case of the organic EL device 101 according to the modification of the present invention, there is also an effect of improving the luminance characteristic or reducing the power consumption by increasing the transmittance.

Referring to FIGS. 2 and 3, a second substrate 110 for encapsulation corresponding to the first substrate 110 of the organic electroluminescent device 101 according to the first embodiment or the modification example having the above- (170) is spaced apart from the first substrate (110). The first substrate 110 and the second substrate 170 are provided with an adhesive agent (not shown) made of a sealant or a frit along the edges of the first substrate 110 and the second substrate 170. And the second substrate 170 are adhered to each other to maintain the panel state.

An atmosphere of vacuum is formed between the first substrate 110 and the second substrate 170 which are spaced apart from each other or filled with an inert gas to form an inert gas atmosphere.

The second substrate 170 for the encapsulation may be made of plastic having a flexible property, or may be made of a glass substrate.

Meanwhile, the organic electroluminescent device 101 according to the first embodiment and the modified examples described above includes a second substrate 170 for encapsulation, which is spaced apart from the first substrate 110 However, the second substrate 170 may be configured to contact the second electrode 158 provided on the uppermost layer of the first substrate 110 in the form of a film including an adhesive layer.

3, in the case of the organic EL device 101 according to the modification of the first embodiment of the present invention, an organic insulating film (not shown) or an inorganic film (not shown) is formed on the second electrode 158 having the single- In the case where the insulating film 162 is formed, the organic insulating film (not shown) or the inorganic insulating film 162 is used as an encapsulation film itself, so that the second substrate 170 may be omitted.

FIG. 4 is a cross-sectional view of a first embodiment of the present invention in which the second electrode has a double-layer structure of a magnesium-silver alloy and a transparent conductive oxide, and FIG. FIG. 3 is a graph illustrating transmittance of an organic electroluminescent device according to a modified example of the first embodiment of the present invention and a second electrode of a magnesium-silver alloy single layer structure, according to wavelengths. In this case, in the comparative example, the second electrode having a single layer structure of a magnesium-silver alloy was formed to have a thickness of 150 ANGSTROM and 240 ANGSTROM, respectively. In the first embodiment and the modified example, Lt; RTI ID = 0.0 > 240A. ≪ / RTI >

Referring to the drawings, in the case of a comparative example (hereinafter referred to as a first comparative example) having a first electrode, a modification, and a second electrode made of a magnesium-silver alloy having a thickness of about 150 Å, (First embodiment), 25% to 36% (variant), and 26% to 36% transmittance for light of 470 to 630 nm wavelength band emitting blue light, respectively, (Hereinafter referred to as second comparative example) having a second electrode made of a magnesium-silver alloy having a thickness of about 10 nm, the transmittance is significantly lower than that of the first comparative example, the first embodiment, and the modified example, To 18%. ≪ / RTI >

Particularly, in the case of the light having a wavelength of 550 nm which indicates green, the transmittance is 33% in both cases of the first embodiment, the modification and the first comparative example, but in the second comparative example, the transmittance is 14% Able to know.

In the case of the comparative example, when the thickness of the second electrode made of only the magnesium-silver alloy is reduced to 200 ANGSTROM or less, the electrode can be used as a display device having an average transmittance of about 15% There is a problem that the power consumption is increased. When the second electrode made of only the magnesium-silver alloy as in the second comparative example has a thickness of more than 200 Å and a thickness of about 240 Å, for example, the sheet resistance can be lowered. It can be seen that the average transmittance for the 470 nm to 630 nm wavelength band light is less than 15%.

However, according to the first embodiment and the modification of the present invention, the transmittance of the light of the wavelength range of 470 nm to 630 nm is 30% or more, even if the thickness of the portion made of the magnesium-silver alloy is 200 Å or more, .

Therefore, in consideration of these experimental results, the organic electroluminescent device according to the first embodiment and the modified example of the present invention reduces the sheet resistance of the second electrode and improves the transmittance of visible light in the wavelength range of 470 nm to 630 nm The organic electroluminescent device according to the first and second comparative examples will have a remarkable effect compared to the organic electroluminescent device according to the first and second comparative examples.

FIG. 5 is a cross-sectional view of one pixel region of an organic electroluminescent device according to a second embodiment of the present invention, except for the structure of the second electrode, includes all the elements formed below the first electrode, Therefore, the same reference numerals as in the first embodiment are assigned to the same constituent elements, and only the second electrode having a different point is given different reference numerals from the first embodiment.

The most characteristic feature of the organic electroluminescent device 101 according to the second embodiment of the present invention is that the second electrode 257 has a multilayer structure. That is, the second electrode 257 is formed of a metal material such as silver (Ag), magnesium-silver alloy (Ag), gold (Au), magnesium (Mg) A first layer 258 made of any one of copper (Cu) and calcium (Ca), a second layer 259a made of indium-tin-oxide or indium-zinc-oxide, which is a transparent conductive material, A third layer 259b made of any one of silver (Ag), gold (Au) and copper (Cu), which is a resistive metal material, and a fourth layer 259c made of the same material as the aforementioned second layer 259a And has a four-layered structure.

At this time, the first layer 258 has a thickness of about 10 to 50 angstroms, and the total thickness of the triple layers of the second to fourth layers 259a to 259c is about 400 to 1000 angstroms. And the third layer 259b made of a metal material has a thickness of about 150 ANGSTROM to 300 ANGSTROM.

In the second embodiment of the present invention, the second electrode 257 is formed to have a four-layer structure in order to maximize the microcurve effect compared to the first embodiment, thereby increasing the light transmittance and lowering the sheet resistance.

In the case of the organic electroluminescent device 101 according to the second embodiment of the present invention, the layer capable of reflecting light in the second electrode 257 is divided into two layers of the first layer 258 and the third layer 259b So that the microcircuit effect can be enhanced compared to the first embodiment in which the layer reflected in the second electrode 257 has only one lower layer.

As a result, the second electrode 257 can have a relatively large overall thickness by increasing the transmittance by increasing the microcavity effect, thereby improving the low-resistance characteristic and lowering the sheet resistance.

In the case of the organic electroluminescent device 101 having the second electrode 257 having a four-layer structure according to the second embodiment of the present invention, the sheet resistance of the second electrode 257 itself is 1.9? /? To 5? /? □, and the light transmittances of the red, green and blue wavelength ranges are respectively 50% or more, which is superior to the first embodiment in terms of sheet resistance reduction and transmittance improvement.

Table 3 shows a second embodiment of the present invention having an organic electroluminescent device in which a second electrode having a single layer structure of magnesium-silver alloy (Mg: Ag) is formed as a comparative example and a second electrode 158 having a four-layer structure The sheet resistance of an organic electroluminescent device according to an example and the transmittance of light at a specific wavelength band.

Comparative Example: Single layer (MgAg) Example 2: Four layers (MgAg + IZO + Ag + IZO) Sheet resistance (Ω / □) 9.9 (Ω / □) 1.9 (Ω / □)
Permeability (%)
Light of 470nm wavelength 15.8% 73.7% 550nm wavelength light 11.9% 73.1% 630nm wavelength light 9.2% 54.9%

Referring to Table 3, in the case of the comparative example having the second electrode having a single layer structure of magnesium-silver alloy (Mg: Ag), when the thickness was formed to have a sheet resistance of about 9.9? /? , And the transmittance for light having a wavelength band of 630 nm is 15.8%, 11.9%, and 9.2%, respectively.

On the other hand, the second layer (259a in FIG. 5) of the magnesium-silver alloy (Mg: Ag) (258 of FIG. 5) and the third layer of indium-zinc- In the case of the second embodiment of the present invention having the second electrode (257 of FIG. 5) having a quadruple-layer structure of the fourth layer (259b of FIG. 5) and the fourth layer of indium-zinc- Even when the first layer to the fourth layer (258 to 259c in FIG. 5) are formed to have a proper thickness and the sheet resistance is set to about 1.9? / ?, the respective transmittances for light having wavelength bands of 470 nm, 550 nm, Are 73.7%, 73.1% and 54.9%, respectively.

Accordingly, it can be seen that the second embodiment according to the present invention including the second electrode (257 in FIG. 5) having a four-layer structure has improved luminance characteristics four times or more as compared with the comparative example having the second electrode having a single layer structure .

Further, in comparison with the second embodiment of the present invention and the first embodiment of the present invention having the second electrode (158 in FIG. 2) of a double-layer structure, referring to Tables 1 and 3, It is understood that the second embodiment of the present invention having the electrode (257 in FIG. 5) is more excellent in terms of sheet resistance reduction than the first embodiment, and 1.3-2 times more in terms of the transmittance.

6 is a graph showing the transmittance of the second embodiment of the present invention in which the second electrode has a quadruple layer structure and the transmittance of the organic electroluminescent device according to the comparative example in which the second electrode has a magnesium-silver alloy single layer structure . In this case, in the comparative example, the transmittance of the second electrode having a single layer structure of magnesium-silver alloy was formed to have a thickness of 140 ANGSTROM. In the case of the second embodiment, the first layer made of magnesium- The second layer and the fourth layer of zinc oxide (IZO) each have a thickness of 400 ANGSTROM and the third layer of silver (Ag) has a thickness of 240 ANGSTROM (represented by 'Example 2-1' The second layer and the fourth layer of indium-zinc-oxide (IZO) each have a thickness of 400 angstroms and the third layer of silver (Ag) has a thickness of 300 angstroms (Shown as Example 2-2 ').

Referring to the drawings, in the case of the second embodiment of the present invention having the second electrode of the four-layer structure, the transmittance is about 54% to 73% for light in the wavelength range of 470 nm to 630 nm emitting red, green and blue light .

However, it can be seen that the comparative example having the second electrode having a monolayer structure of a magnesium-silver alloy has a transmittance of 26% to 36% with respect to light of 470 nm to 630 nm which emits red, green and blue light .

Therefore, it can be seen that the organic electroluminescent device according to the second embodiment of the present invention having a quadruple layer structure in terms of transmittance is far superior to the comparative example having the second electrode having a single layer structure.

On the other hand, in recent years, display devices have become large-sized, and thus the sheet resistance of the second electrodes formed in a plate shape over the entire display area has become a big issue. It is possible to provide a display device with excellent display quality free from errors in the central portion and the side portion of the display region, as long as the surface area of the second electrode becomes smaller as the surface is larger.

Therefore, in the organic electroluminescent device, it is required to have a technique in which the sheet resistance of the second electrode formed in the form of a plate on the entire surface of the display region is set to a level of 2? /? Or less, preferably about 1? /? .

The third embodiment of the present invention provides an organic electroluminescent device in which a second electrode having a sheet resistance of 2? /? Or less is implemented in response to this demand.

7 is a cross-sectional view of one pixel region of an organic electroluminescent device according to the third embodiment of the present invention, except for the structure of the second electrode, all of which are formed below the same, (Only the portion indicated by A in Fig. 5) is shown.

The third embodiment of the present invention is characterized in that the second electrode 357 having a sheet resistance of 2 OMEGA / & squ & while serving as a cathode electrode is provided with an organic electroluminescent light emission having a transmittance of 30% or more for red, Device.

The most characteristic feature of the organic electroluminescent device according to the third embodiment of the present invention is that the second electrode 357 has a multi-layer structure more than that of the first embodiment and can maximize the micro- .

That is, the second electrode 357 according to the third embodiment of the present invention is formed of a metal material having a relatively low work function value such as silver (Ag), a magnesium-silver alloy (Mg) A first layer 358 made of any one material of gold (Au), magnesium (Mg), copper (Cu), and calcium (Ca) A second layer 359a made of indium-tin-oxide or indium-zinc-oxide which is a transparent conductive material and a second layer 359b made of low resistance metal such as silver (Ag), gold (Au) (Hereinafter referred to as a set layer 359) of a fourth layer 359c made of the same material and constituting the third layer 359b made of any one of the above materials and the aforementioned second layer 359a, The set layers 360 (360a, 360b, and 360c), which are three layers above the fourth layer 359c, are formed once again. Thus, according to the third embodiment of the present invention And the second electrode 357 has a total of seven layers.

 In the case of an organic electroluminescent device (not shown) according to the third embodiment of the present invention, the second electrode 357 is formed of a first layer 358 and first and second set layers 359 and 360 (Not shown) is further provided on the second set layer as a modification of the third embodiment of the present invention to form a ten-layer or a thirteen-layer structure .

In such a configuration, the layer in which light is reflected in the second electrode 357 is further extended, thereby maximizing the microcurve effect. Therefore, even if the number of layers made of the low-resistance material is increased among the plurality of layers constituting the second electrode 357, the transmittance is not lowered, so that the sheet resistance of the entire second electrode 357 .

In the third embodiment of the present invention, the first layer 358 has a thickness of about 10 Å to about 50 Å, and the first layer 358 has a thickness of about 10 Å to about 50 Å. The second layer to the seventh layer 359 a, 359 b, 359 c, 360 a, 360 b, The total thickness of the middle layer is about 800 Å to 2000 Å, and the thickness of the third layer 359b and the sixth layer 360b made of the low-resistance metal material is about 150 Å to 300 Å, respectively.

8 shows a third embodiment of the present invention having a second electrode having a six layer of IZO / Ag / IZO / IZO / Ag / IZO over a first layer of a magnesium-silver alloy (Mg: Ag) Ag / IZO / Ag (IZO / Ag / IZO / Ag / IZO) and the first comparative example having a layer of Ag on the first layer of magnesium-silver alloy / IZO according to the second comparative example having the second electrode provided with the five-layered structure of the organic electroluminescent device. In this case, the layer made of silver (Ag) was formed to have a thickness of 250 angstroms and the layer made of IZO was formed to have a thickness of 400 angstroms in Examples and Comparative Examples.

As shown in the figure, in the second and third embodiments of the present invention, it is understood that the transmittance is 30% or more for each of 470 nm to 600 nm wavelength light emitting red, green and blue light.

However, in the first comparative example having the second layer made of only silver (Ag) on the first layer of the magnesium-silver alloy (Mg: Ag), in the light of the wavelength range of 470 nm to 600 nm, Ag / IZO / Ag / IZO on the first layer of the magnesium-silver alloy (Mg: Ag). In the case of the second comparative example having the IZO / Ag / It can be seen that the light has a transmittance of 20% or less in the light of wavelengths of 470 to 600 nm, particularly in the wavelength band of 530 nm or more, which emits green and blue light.

As a result, in the case of the third embodiment of the present invention, it can be seen that relatively low sheet resistance can be reduced since a layer made of silver (Ag) is provided as a low resistance material, When the third layer and the sixth layer made of silver (Ag) are formed to have a thickness of 250 angstroms, the sheet resistance of the entirety of the second electrode made of the seven-layered structure is about 1? /? It can be seen that the electroluminescent device is superior to the comparative examples and the first and second embodiments in terms of sheet resistance reduction.

FIG. 9 is a cross-sectional view of three pixel regions that emit successive red, green, and blue colors of an organic electroluminescent device according to a fourth exemplary embodiment of the present invention, Are the same as those of the second embodiment described above, and therefore, the second electrode having a different point is mainly shown. For convenience of description, pixel regions emitting red, green, and blue are defined as first, second, and third pixel regions P1, P2, and P3, respectively.

As shown in the figure, organic light emitting layers 455 (455a, 455b, and 455c) having the same thickness and emitting red, green, and blue light are formed in the first, second, and third pixel regions P1, P2, and P3 . Although the organic light emitting layers 455a, 455b, and 455c emitting red, green, and blue light are illustrated as being in contact with each other in the drawing, the boundary between the first, second, and third pixel regions P1, P2, and P3 Green, and blue organic light emitting layers 455a and 455b (not shown) are formed by separating the first, second, and third pixel regions P1, P2, and P3 by such banks (not shown) And 455c are separated and formed.

Next, a second electrode 457 is formed on the entire display region without separating the pixel regions P1, P2, and P3 over the red, green, and blue organic light emitting layers 455a, 455b, and 455c.

The second electrode 457 may be formed of a metal such as silver (Ag), silver-silver (Ag), gold (Au), magnesium (Mg) A first layer 461 made of a material selected from the group consisting of copper (Cu), calcium (Ca) and indium-tin-oxide or indium-zinc- A third layer 463 made of silver (Ag), gold (Au) or copper (Cu) which is a low resistance metal material and a third layer 463 made of the second layer 462 A fourth layer 464 (464a, 464b, 464c) made of the same material and a fifth layer 465 made of the same material forming the third layer 463; And a sixth layer 466 formed of a six-layered structure.

In the fourth embodiment of the present invention, the fourth layer 464 made of the transparent conductive material has different thicknesses for the first, second, and third pixel regions P1, P2, and P3, . That is, the first to third layers 461, 462 and 463, the fifth layer 465 and the sixth layer 466 are displayed regardless of the first, second and third pixel regions P1, P2 and P3 The fourth layer 464 is formed to have different thicknesses for the first, second, and third pixel regions P1, P2, and P3, respectively.

At this time, the fourth layer 464 has the first thickest portion corresponding to the first pixel region P1 having the organic light emitting layer 455a emitting the red light having a relatively long wavelength, A portion corresponding to the third pixel region P3 provided with the organic light emitting layer 455c emitting a short blue light has the second thinnest thickness and the second pixel region 452b having the organic light emitting layer 455b emitting green light P2) is thinner than the first thickness and has a third thickness that is thicker than the second thickness.

At this time, the fourth layer 464 preferably has a thickness of about 400 Å to 1200 Å.

The total thickness of the fifth layer composed of the second to sixth layers 462, 463, 464, 465, and 466 is about 1000 Å to about 2500 Å. The first layer 461 has a thickness of about 10 Å to 50 Å. And the third layer 463 and the fifth layer 465 made of a double low resistance metal material each have a thickness of about 150 ANGSTROM to about 400 ANGSTROM.

The fourth layer 464 made of the transparent conductive material is divided into first, second and third pixel regions P1, P2, and P3 each having red, green and blue organic light emitting layers 455a, 455b, The thickness of the second electrode 457 is set to be in the range of 1? /? To 3? /? 3, □ level.

When a layer made of a transparent conductive material is formed on the upper and lower portions of the layer made of the low resistance metal material having the same thickness, it is improved in terms of the transmittance.

However, when the thickness of the layer made of the low-resistance metal material is formed to have a thickness greater than 400 A so that the sheet resistance level of the second electrode 457 is about 1? /? To 3? / ?, the transmittance is low, Type organic electroluminescent device can not be used as the second electrode.

To solve this problem, the second layer to the fifth layer 462, 463, 464, 465, 466 except for the first layer 461 is formed by IZO / Ag / IZO / Ag / IZO, the transmittance is compensated for and the overall transmittance is improved. However, since the transmittance is improved and the transmittance is improved, the red or blue light other than the second pixel region P2 emitting green light The transmittance in the first and third pixel regions P1 and P2 becomes low.

Therefore, in order to suppress the decrease in the transmittance in the first and third pixel regions P1 and P3 emitting red and blue light, in consideration of the wavelength band of light emitting red, green and blue, The thickness of the layer 464 is formed differently for the first, second, and third pixel regions P1, P2, and P3.

The organic electroluminescent device according to the fourth embodiment of the present invention having such a feature may be formed even if the thickness of the third layer 463 and the fifth layer 465 made of a low resistance metal material is about 300 Å to 400 Å The second layer to the fifth layer 462, 463, 464, 465, and 466 may have an IZO / Ag / IZO / Ag / IZO structure without a thickness difference for each pixel region P1, P2, Which is similar to the transmittance of the electroluminescent device.

Therefore, the organic EL device according to the fourth embodiment of the present invention can form the third layer and the fifth layer 463 and 465, which are made of a low-resistance metal material, to a thickness of about 400 Å while maintaining a certain level of transmittance The sheet resistance of the second electrode 457 itself can be maintained at a level as low as 1? /? To 3? /?, Which is advantageous for the large-scale production.

10 is a graph showing the transmittance of the fourth electrode of the second electrode of the organic electroluminescent device according to the fourth embodiment of the present invention, in which the thickness of the fourth electrode is changed to 600 Å to 1000 Å. In this case, as the first comparative example, only the second layer having the thickness of 250 Å of silver (Ag) was provided in addition to the first layer serving as the cathode, and the second layer to the fourth layer was formed of IZO 400 Å / Ag 250 Å / IZO 400 ANGSTROM, and as a third comparative example, the transmittance of the second layer to the sixth layer having a composition of IZO 400 ANG / Ag 250 ANGSTROM / IZO 400 ANG / Ag 250 ANGSTROM / IZO 400 ANGSTROM was also shown.

As shown in the figure, when the fourth layer is formed to a thickness of 600 Å, 800 Å, and 1000 Å, the transmittance is 0.66, 0.66, and 0.58 at the blue, green, and red wavelength ranges, respectively.

Accordingly, in the first, second and third pixel regions emitting red, green and blue, the thickness of the fourth layer is different, that is, in the first pixel region emitting red light, The second pixel region has a thickness of about 800 ANGSTROM and the third pixel region that emits blue light has a thickness of about 600 ANGSTROM.

However, in the comparative examples 1, 2 and 3, all of the transmittances in the wavelength range of 470 nm to 650 nm indicating red, green, and blue have a transmittance of 0.4 or less.

11 is a cross-sectional view of three pixel regions that emit successive red, green, and blue colors of an organic electroluminescent device according to a fifth embodiment of the present invention, in which all the components Are the same as those of the second embodiment described above, and therefore, the second electrode having a different point is mainly shown. For convenience of description, pixel regions emitting red, green, and blue are defined as first, second, and third pixel regions P1, P2, and P3, respectively.

As shown in the figure, organic light emitting layers 555 (555a, 555b and 555c) having the same thickness and emitting red, green and blue light are formed in the first, second and third pixel regions P1, P2 and P3 . Although the organic light emitting layers 555a, 555b and 555c emitting red, green and blue light are shown as being in contact with each other in the drawing, the boundary between the first, second and third pixel regions P1, P2 and P3 Green and blue organic light emitting layers 555a and 555b are formed by separating the first, second and third pixel regions P1, P2 and P3 by such banks (not shown) And 555c are separated and formed.

Next, a second electrode 557 is formed on the entire display region without separating between the pixel regions P1, P2, and P3 over the organic light emitting layers 555a, 555b, and 555c emitting red, green, and blue light.

The second electrode 557 may be formed of a metal such as silver (Ag), silver-silver (Ag), gold (Au), magnesium (Mg) A first layer 561 made of a material selected from the group consisting of copper (Cu), calcium (Ca) and indium-tin-oxide or indium-zinc- A third layer 563 made of silver (Ag), gold (Au) or copper (Cu), which is a low resistance metal material, and a third layer 563 made of an organic material such as a material A fourth layer 564 (564a, 564b, 564c) made of benzocyclobutene or photoacryl or a material forming the organic light emitting layer and a fifth layer 565 made of the same material making the third layer 563, , And a sixth layer 566 made of the same material that constitutes the second layer 562.

In the fifth embodiment of the present invention, the fourth layer 564 made of the organic material is spaced apart from the first, second, and third pixel regions P1, P2, and P3 and has different thicknesses A third layer 563 and a fifth layer 565 made of a low-resistance metal material are formed on the lower and upper portions of the fourth layer 564 with the pixel regions P1, P2, P3, that is, the fourth layers 564a, 564b, and 564c that are spaced apart from each other.

At this time, the fourth layers 564a, 564b, and 564c formed with different thicknesses for the first, second, and third pixel regions P1, P2, and P3 are formed in the organic light emitting layer 555a corresponding to the first pixel region P1 correspond to the third pixel region P3 having the thickest first thickness and the organic light emitting layer 555c emitting the shortest wavelength of blue light A portion corresponding to the second pixel region having the green organic light emitting layer is thinner than the first thickness and has a third thickness greater than the second thickness.

At this time, the fourth layer 564 preferably has a thickness of about 400 Å to 1200 Å.

The total thickness of the fifth layer composed of the second to sixth layers 562, 563, 564, 565 and 566 is about 1000 to 2500 angstroms And the third layer 563 and the fifth layer 565 made of the double low resistance metal material have a thickness of about 150 Å to about 400 Å, respectively.

The fourth layer 564 made of the organic material is divided into the first, second and third pixel regions P1, P2, and P3 provided with the organic light emitting layers 555a, 555b, and 555c emitting red, The thickness of the third layer 563 and the second layer 563 are improved by improving the transmittance of the emitted light in the first, second and third pixel regions P1, P2 and P3 as described in the fourth embodiment. The thickness of the fifth layer 565 is set to about 400 ANGSTROM so that the surface resistance of the second electrode 557 is about 1? /? To 3? / ?.

The organic electroluminescent device according to the fifth embodiment of the present invention having such a constitutional feature also overlaps the fourth layer 564 in the third layer 563 and the fifth layer 565 made of a low- The second layer to the fifth layer 562, 563, 564, 565, and 566 are formed in a thickness-wise manner for each pixel region P1, P2, and P3 in terms of transmittance IZO / Ag / IZO / Ag / IZO having a structure similar to that of the organic electroluminescent device having the structure of IZO / Ag / IZO / Ag / IZO.

Accordingly, the organic light emitting device according to the fifth embodiment of the present invention may include a third layer 563 made of a low-resistance metal material and a fourth layer 564 of the fifth layer 565 while maintaining a certain level of transmittance, The sheet resistance of the second electrode 557 itself can be maintained at a level as low as 1? /? To 3? /?, Which is advantageous in the large-sized configuration.

FIG. 12 is a graph showing transmittance of a fourth electrode of a second electrode of an organic electroluminescent device according to a fifth embodiment of the present invention, in which the thickness of the fourth electrode is changed to 800 ANGSTROM to 1200 ANGSTROM. In this case, as a first comparative example, in addition to the first layer serving as a cathode, the second to fourth layers have a structure of IZO 400 Å / Ag 250 Å / IZO 400 Å, and the second to sixth layers IZO 400 Å / Ag 250 Å / IZO 800 Å / Ag 250 Å / IZO 400 Å, and as a second comparative example, the second to sixth layers have a composition of IZO 400 Å / Ag 250 Å / IZO 400 Å / Ag 250 Å / The transmittance of the organic EL device having the IZO 400 ANGSTROM structure is also shown.

As shown in the figure, when the fourth layer is formed as an organic material, for example, 800 Å, 1000 Å and 1200 Å, transmittances of 0.78, 0.7, and 0.7 are obtained at wavelengths of 470 nm, 550 nm, and 630 nm, 0.67, respectively.

Therefore, the thickness of the fourth layer is different for each of the first, second, and third pixel regions P1, P2, and P3 emitting red, green, and blue light, that is, The second pixel region emitting green light has a thickness of about 1000 angstroms and the third pixel region emitting blue light has a thickness of about 800 angstroms so that the final summed transmittance is more than 0.58.

It can be seen that the first comparative example has a transmittance of about 0.4 to 0.7 in the wavelength range of 470 nm to 630 nm and has a transmittance of about 0.4 in the wavelength range of 470 nm to 600 nm in the second embodiment, In the case of the example, it can be seen that the transmittance is about 0.1 to 0.3 in the wavelength range of 470 nm to 600 nm.

Therefore, in the case of the fifth embodiment of the present invention, the average transmittance is 0.58 or more, so that the second electrode is the transmittance level of the first comparative example having the total four-layer structure including the first layer serving as the cathode electrode And the transmittance is much better than that of the third comparative example having a total six-layered structure.

FIGS. 13 and 14 are cross-sectional views, respectively, of a display region of an organic electroluminescent device according to a modification of the sixth and sixth embodiments of the present invention. Layer structure is provided on the second electrode of the organic electroluminescent device according to the second embodiment. For convenience of explanation, the same components shown in the second embodiment are denoted by the same reference numerals Respectively.

The organic electroluminescent device according to the sixth embodiment of the present invention and its modification is characterized in that it is an encapsulation layer for encapsulation formed on the second electrode, The organic electroluminescent device according to any one of the second to fifth embodiments is characterized in that the second electrode has a multilayer structure of a triple or more layer and the uppermost layer is made of a transparent conductive material. The encapsulation film is mainly described since it has the same configuration as any one.

Referring to FIG. 13, an organic electroluminescent device 601 according to a sixth embodiment of the present invention includes an encapsulation layer (not shown) having a multilayer structure on the second electrode 257 of the organic electroluminescent diode E 772 are provided.

At this time, the encapsulation film 772 is formed of an organic material, more precisely, an organic film 772a or 772c made of a monomer or polymer and an inorganic film 772b or 772d made of an inorganic insulating material, Which are laminated together.

 Generally, the encapsulation layer generally has a five-layer structure in which an organic film and an inorganic film alternate.

However, since the uppermost layer 259c of the second electrode 257 is formed of a transparent conductive material in the organic electroluminescent device 601 according to the sixth embodiment of the present invention, The lowest layer made of the inorganic film (not shown) of the encapsulation film 772 is used as the uppermost layer 259c of the second electrode 257 made of a transparent conductive material so that the organic film and the inorganic film alternate Layer structure of the first organic film 772a / the first inorganic film 772b / the second organic film 772c / the second inorganic film 772d.

In the case of the organic EL device 601 according to the sixth embodiment of the present invention having such a structure, since the encapsulation film 772 is formed of a quadruple layer, It is possible to omit the number of layers, thereby simplifying the manufacturing process.

14, in the case of the organic electroluminescent device 701 according to the modification of the sixth embodiment, the encapsulation film 772 is formed of a transparent conductive material among the second electrodes 257 having a multilayer structure The first inorganic film 772a / the first organic film 772b / the second inorganic film (not shown) is formed on the low-resistance material layer 259b of FIG. 5 by omitting the uppermost layer 259c 772c, a second organic film 772d, and a third inorganic film 772e.

In the case of the organic electroluminescent device 701 according to the modification of the sixth embodiment, the uppermost layer (259c in FIG. 5) made of the transparent conductive material of the second electrode 257 is omitted and an encapsulation layer The first inorganic film 772a which is the lowermost layer of the second insulating film 772 has the effect of simplifying the manufacturing process.

In the case of the organic EL device 701 according to the modification of the sixth embodiment, the second electrode 257 of the organic electroluminescent diode E alternates between the transparent conductive material layer and the low-resistance material layer, The organic EL device 701 according to the modified example of the sixth embodiment of the present invention is not limited to the organic EL device according to the fifth embodiment of the present invention. 11), which are different in the first, second and third pixel regions (P1, P2, and P3 in FIG. 11) emitting blue, green and red light, are formed in the second electrode through the organic electroluminescent device When the organic material layer (564 in FIG. 11) is interposed, the thickness of the organic material layer (564 in FIG. 11) can be controlled to prevent a reduction in transmittance improvement.

The present invention is not limited to the above-described embodiments and modifications, and various modifications may be made without departing from the spirit of the present invention.

101: organic electroluminescent device 110: first substrate
113: semiconductor layers 113a and 113b: first and second regions
116: gate insulating film 120: gate electrode
123: interlayer insulating film 125: semiconductor layer contact hole
133: source electrode 136: drain electrode
140: protective layer 143: drain contact hole
147: first electrode 147a: first layer
147b: second layer 150: bank
155: organic light emitting layer 155a: hole injection layer
155b: hole transport layer 155c: organic light emitting material layer
155d: electron transport layer 155e: electron injection layer
158: second electrode 158a: lower layer (of the second electrode)
158b: upper layer (of the second electrode)
DA: driving region DTr: driving thin film transistor
P: pixel area

Claims (27)

delete delete delete delete delete delete delete A first substrate on which a display region having a plurality of pixel regions is defined;
A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 first transparent conductive layer formed on the organic light emitting layer and the bank, the first transparent conductive oxide being formed on the entire surface of the display region, the first layer having a first thickness made of a first metal, And a first set of three layers of a low resistance metal layer made of a low resistance metal material and a second transparent conductive layer made of a transparent conductive oxide,
/ RTI >
And an image is displayed using light emitted from the organic light emitting layer toward the second electrode.
9. The method of claim 8,
And the second electrode has a sheet resistance of 1.9? /? To 5? / ?.
9. The method of claim 8,
Wherein the second electrode further comprises a second set layer formed of a triple layer having the same structure as the first set layer on the first set layer.
11. The method of claim 10,
And the second electrode has a sheet resistance of 1? /? To 2? / ?.
11. The method according to claim 8 or 10,
The first layer is made of any one of Ag, Mg, Ag, Mg, Cu,
The first and second transparent conductive layers are made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO)
Wherein the low resistance metal layer is made of one of silver (Ag), gold (Au), and copper (Cu).
11. The method of claim 10,
The first layer has a thickness of 10 A to 50 A,
Wherein each of the first and second set layers has a thickness of 400 ANGSTROM to 1000 ANGSTROM and the low resistance metal layer provided in the first and second set layers has a thickness of 150 ANGSTROM to 300 ANGSTROM, .
A first substrate on which a display region having a plurality of pixel regions is defined;
A switching thin film transistor and a driving thin film transistor formed in the respective pixel regions 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 in the bank and emitting red, green, and blue light for each pixel region;
A first layer made of a first metal formed on the entire surface of the display region on the organic light emitting layer and the bank, a second layer made of a transparent conductive oxide, a third layer made of a low resistance metal material, A fourth layer made of the transparent conductive oxide or organic material, a fifth layer made of the low-resistance metal material, and a sixth layer made of the transparent conductive oxide,
Wherein the fourth layer is formed to have a different thickness for each pixel region having the organic light emitting layer emitting red, green and blue light.
15. The method of claim 14,
The fourth layer has a thickness of 600 ANGSTROM to 1200 ANGSTROM and the portion overlapping the organic light emitting layer emitting blue light has the thinnest thickness and the portion overlapping the organic light emitting layer emitting red light has the largest thickness Organic electroluminescent device.
15. The method of claim 14,
The first layer has a thickness of 10 A to 50 A,
And the third layer and the fifth layer made of the low-resistance metal material each have a thickness of 150 ANGSTROM to 400 ANGSTROM.
15. The method of claim 14,
The first layer is made of any one of Ag, Mg, Ag, Mg, Cu,
Wherein the transparent conductive oxide is indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and the organic material is any one of photoacryl, benzocyclobutene,
Wherein the low resistance metal material is one of silver (Ag), gold (Au), and copper (Cu).
15. The method of claim 14,
And the second electrode has a sheet resistance of 1? /? To 3? / ?.
15. The method of claim 14,
The fourth layer is formed to be spaced apart from the boundary of each pixel region when the fourth layer is made of the organic material, and the third layer and the fifth layer are formed so as to contact each other at the boundaries of the pixel regions Organic electroluminescent device.
The method according to any one of claims 8, 10 and 14,
Wherein the switching and driving thin film transistor is a p-type thin film transistor, the first electrode serves as an anode electrode, and the second electrode serves as a cathode electrode.
21. The method of claim 20,
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 high work function value, A first layer made of any one of aluminum (Al), aluminum alloy (AlNd), and silver (Ag) which is in contact with and has excellent reflectivity and a second layer made of the transparent conductive material and in contact with the organic light emitting layer Layer structure. ≪ IMAGE >
The method according to any one of claims 8, 10 and 14,
Wherein a gate wiring and a data wiring crossing each other and defining the pixel region are formed on the first substrate, and a power supply wiring arranged in parallel with the data wiring is formed, and the gate and the data wiring are respectively connected to the gate electrode and the data wiring of the switching thin- Wherein the source electrode is connected to the organic electroluminescent device.
The method according to any one of claims 8, 10 and 14,
And a second transparent substrate facing the first substrate and encapsulating the first substrate.
24. The method of claim 23,
Wherein the second substrate is formed in contact with the second electrode and has a multi-layer structure in which an inorganic film and an organic film alternate with each other.
25. The method of claim 24,
Wherein the second substrate has a four-layer structure of an organic film / an inorganic film / an organic film / an inorganic film.
25. The method of claim 24,
The second substrate has a five-layered structure of an inorganic film / an organic film / an inorganic film / an organic film / an inorganic film, and the second electrode contacting the second substrate is omitted from the uppermost layer made of a transparent conductive oxide, Is in contact with a layer of a low-resistance material of the second electrode.
25. The method of claim 24,
The inorganic film is made of any one of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), and silicon nitride (SiNx)
Wherein the organic film is made of a monomer or a polymer.

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