KR20120052851A - Organic electro-luminescent device - Google Patents

Abstract

The present invention provides a display device comprising: a first substrate on which a display area having a plurality of pixel areas is defined; A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor; A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region; An organic emission layer formed on the first electrode in the bank; A second electrode formed on the organic light emitting layer and the bank above the display area, and having a double layer structure having a first thickness lower layer made of a metal material having a low work function value and a second thickness upper layer made of a transparent conductive oxide; It provides an organic light emitting device comprising a.

Description

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 characterized by improving transmittance of a cathode electrode while maintaining low resistance in an upper light emitting structure.

The organic light emitting diode, which is one of the flat panel displays (FPDs), has high luminance and low operating voltage characteristics. In addition, the self-luminous self-illuminating type provides high contrast ratio, enables ultra-thin display, easy response time with several microsecond response time, no restriction on viewing angle, and stable at low temperatures. And, since it is driven at a low voltage of DC 5V to 15V it is easy to manufacture and design a drive circuit.

In addition, the manufacturing process of the organic light emitting device is very simple because the deposition (deposition) and encapsulation (encapsulation) equipment is all.

Therefore, the organic light emitting device having the above-described advantages has been recently used in various IT devices such as TVs, monitors, and mobile phones.

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

The organic light emitting device is largely composed of an array device and an organic light emitting 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, an organic light emitting layer, and a second electrode connected to the driving thin film transistor. It consists of electrodes.

In the organic light emitting device having such a configuration, light generated from the organic light emitting layer is emitted toward the first electrode or the second electrode to display an image. Such an organic light emitting device is manufactured by a top emission method of displaying an image by 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 light emitting device, the second electrode located above the organic light emitting layer cannot be formed by sputtering, which is a deposition method of a general metal material, to prevent damage to the organic light emitting layer, and is usually formed by vacuum thermal deposition. It's happening.

Meanwhile, the first electrode is made of indium tin oxide (ITO), a transparent conductive material having a high work function value to serve as an anode electrode, and the second electrode has a low work function value to serve as a cathode electrode. It is made of metal material.

However, since the metal material having a low work function value constituting the second electrode serving as a cathode electrode has an opaque property, when the opaque metal is formed to have a general electrode thickness, that is, a thickness of 1000 kPa to 4000 kPa Light cannot penetrate.

Therefore, in order to secure transparency, the second electrode having a low work function value and an opaque metal material is formed to have a thickness of about 10 kPa to about 200 kPa. In this case, since the light transmittance of the second electrode is 15% or more, the luminance level of the general display device is increased.

 However, when the second electrode is formed to have a thickness of about 10 k? To 200 k ?, the sheet resistance is 20 k? /? To 1000 k? / ?, and in this case, the resistance of the second electrode itself is high and the driving voltage becomes very large, thus consuming power. The increase has led to rapid battery consumption, especially when applied to personal portable IT devices.

The present invention has been made to solve the above problems, an object of the present invention is to improve the light transmittance without increasing the resistance of the second electrode itself of the organic light emitting diode formed on the top layer of the organic light emitting device of the top emission method. An object of the present invention is to provide an organic light emitting device.

An organic light emitting display device according to an embodiment of the present invention for achieving the above object comprises: a first substrate having a display area having a plurality of pixel areas; A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor; A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region; An organic emission layer formed on the first electrode in the bank; A second electrode formed on the organic light emitting layer and the bank, and formed on the entire display area, and having a double layer structure having a lower layer of a first thickness made of magnesium-silver alloy and an upper layer of a second thickness made of a transparent conductive oxide on the lower layer; It includes.

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

In accordance with still another aspect of the present invention, an organic light emitting display device includes: a first substrate on which a display area having a plurality of pixel areas is defined; A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor; A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region; An organic emission layer formed on the first electrode in the bank; A second electrode having a first thickness formed on an entire surface of the display area above the organic emission layer and the bank, and having a single layer structure of a magnesium-silver alloy; And a transparent insulating layer in contact with the second electrode and formed over the display area.

In this case, the transparent insulating layer is made of silicon oxide (SiO ₂ ) or aluminum oxide (Al ₂ O ₃ ), which is an inorganic insulating material, or a polymer or monomer made of an organic insulating material.

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

In addition, the first electrode may have a single layer structure made of indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive material having a high work function value, or may be a drain of the driving thin film transistor. A first layer made of any one of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), which are in contact with the electrode and have excellent reflectivity, and a second layer made of the transparent conductive material and in contact with the organic light emitting layer It is characterized by forming a double layer structure consisting of.

In addition, a gate wiring and a data wiring defining the pixel region and a power wiring disposed to be parallel to the data wiring are formed on the first substrate, and the gate and the data wiring are respectively formed as gates of the switching thin film transistor. It is characterized by being connected to the electrode and the source electrode.

In accordance with still another aspect of the present invention, an organic light emitting display device includes: a first substrate on which a display area having a plurality of pixel areas is defined; A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor; A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region; An organic emission layer formed on the first electrode in the bank; A low-resistance metal layer formed over the organic light-emitting layer and the bank and over the display area, the first layer having a first thickness of a first metal, a first transparent conductive layer made of a transparent conductive oxide, and a low resistance metal material And a set layer formed of a triple layer of a second transparent conductive layer made of a transparent conductive oxide and stacked on top of the first layer to form a structure of the first layer and the first set layer.

At this time, the second electrode is characterized in that the sheet resistance of 1.9 Ω / □ to 5 Ω / □.

In addition, 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 kW / It is characterized by being from □ to 2 dB / □.

The first layer is made of one of silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg), copper (Cu), calcium (Ca), and the transparent conductive layer It is made of indium tin oxide (ITO) or indium zinc oxide (IZO), and the low resistance metal layer is characterized by being made of any one of silver (Ag), gold (Au), and copper (Cu).

The first layer has a thickness of 10 kPa to 50 kPa, the first and second set layers each have a thickness of 400 kPa to 1000 kPa, and the low resistance metal layer provided in the first and second set layers is respectively The thickness is 150 kPa to 300 kPa.

In accordance with still another aspect of the present invention, an organic light emitting display device includes: a first substrate on which a display area having a plurality of pixel areas is defined; A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor; A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region; An organic light emitting layer formed on the first electrode in the bank and emitting red, green, and blue light for each pixel area; 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 formed on the entire display area over the organic light emitting layer and the bank; A fourth electrode made of an oxide or an organic material, and a second electrode made of a six-layer structure of 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 The thickness of each pixel area of the organic light emitting layer that emits red, green, and blue light is different.

In this case, the fourth layer has a thickness of 600 Å to 1200 ,, the portion overlapping with the organic light emitting layer emitting blue light has the thinnest thickness, and the portion overlapping with the organic light emitting layer emitting red light has the thickest thickness. Is characteristic.

The first layer has a thickness of 10 kPa to 50 kPa, and the third layer and the fifth layer made of the low resistance metal material have a thickness of 150 kPa to 400 kPa, respectively.

In this case, the first layer is made of silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg), copper (Cu), calcium (Ca), the transparent conductive The oxide is indium tin oxide (ITO) or indium zinc oxide (IZO), and the organic material is any one of photoacryl, benzocyclobutene or a material forming the organic light emitting layer, and the low resistance metal material is silver (Ag), gold (Au), and copper (Cu), wherein the second electrode has a sheet resistance of 1 kW / □ to 3 kW / □.

Further, when the fourth layer is made of the organic material, the fourth layer is formed to be spaced apart from the boundary of each pixel region, and the third layer and the fifth layer are in contact with each other at the boundary of the pixel region. It is characterized by the formation.

The switching and driving thin film transistor becomes a p-type thin film transistor, wherein the first electrode serves as an anode electrode, the second electrode serves as a cathode electrode, the first electrode is a work function value Aluminum, which is a highly transparent conductive material and has a single layer structure composed of indium tin oxide (ITO) or indium zinc oxide (IZO), which is a highly transparent conductive material, or is in contact with the drain electrode of the driving thin film transistor and has excellent reflectivity. And a first layer made of any one of (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.

In addition, a gate wiring and a data wiring defining the pixel region and a power wiring disposed to be parallel to the data wiring are formed on the first substrate, and the gate and the data wiring are respectively formed as gates of the switching thin film transistor. It is characterized by being connected to the electrode and the source electrode.

In addition, it is characterized in that a transparent second substrate for encapsulation facing and corresponding to the first substrate.

In this case, the second substrate is formed in contact with the second electrode and is characterized in that a multi-layer structure of the form in which the inorganic film and the organic film is alternated.

The second substrate may have a quad layer structure of an organic film, an inorganic film, an organic film, and an inorganic film.

In addition, the second substrate has a five-layered structure of an inorganic film, an organic film, an inorganic film, an organic film, and an inorganic film, and the second electrode in contact with the second substrate is omitted because the uppermost layer made of a transparent conductive oxide is omitted. The second substrate is characterized in contact with the layer of 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 ), silicon nitride (SiNx), the organic film is characterized by consisting of a monomer or a polymer.

The top emission type organic light emitting device according to the present invention is a metal material having a low work function value and is formed of a double layer structure including a metal layer having a thickness of about 10 μs to 200 μs and a transparent transparent conductive material or a conductive metal layer of transparent metal oxide. Forming two electrodes or forming a metal layer having a low work function value and having a metal layer having a thickness of about 10 μs to 200 μs and an organic insulating material layer on top thereof causes surface plasmon to occur so that the sheet resistance is 10 μs / □ or less At the same time there is an effect to improve the transmittance of light.

1 is a circuit diagram of one pixel of a general organic light emitting diode.
2 is a cross-sectional view of a part of a display area of an organic light emitting diode according to a first exemplary embodiment of the present invention.
3 is a cross-sectional view of a part of a display area of an organic light emitting diode according to a modification of the first exemplary embodiment of the present invention.
4 shows 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 the second electrode has a magnesium-silver alloy single layer structure, on which an organic or inorganic insulating film is formed. A graph showing transmittance for each wavelength of an organic light emitting diode according to a comparative example including an organic light emitting diode according to a modified example of the first embodiment and a second electrode having a magnesium-silver alloy single layer structure.
5 is a cross-sectional view of one pixel area of an organic light emitting diode according to a second exemplary embodiment of the present invention.
FIG. 6 is a graph illustrating wavelength-specific transmittance of an organic light emitting diode according to a second exemplary embodiment of the present invention in which the second electrode has a quad layer structure and a comparative example in which the second electrode has a magnesium-silver alloy single layer structure.
7 is a cross-sectional view of one pixel area of an organic light emitting diode according to a third exemplary embodiment of the present invention.
8 shows a third embodiment of the invention with a second electrode with a six layer of IZO / Ag / IZO / IZO / Ag / IZO over a first layer of magnesium-silver alloy (Mg: Ag) and IZO / First embodiment of the present invention with a triple layer of Ag / IZO and a first comparative example with a layer made of Ag over a first layer of magnesium-silver alloy (Mg: Ag) and IZO / Ag / IZO / Ag A graph showing the transmittance of each organic wave of the organic light emitting device according to the second comparative example having a second electrode provided with a five-layer of / IZO.
FIG. 9 is a cross-sectional view of three pixel areas respectively emitting red, green, and blue light in succession of the organic light emitting device according to the fourth embodiment of the present invention; FIG.
10 is a graph measuring transmittance while changing the thickness of the fourth layer of the second electrode of the organic light emitting device according to the fourth embodiment of the present invention to have a thickness of 600 mW to 1000 mW.
FIG. 11 is a cross-sectional view of three pixel areas respectively emitting red, green, and blue light in succession of the organic light emitting diode according to the fifth embodiment of the present invention; FIG.
12 is a graph measuring transmittance while changing the thickness of the fourth layer of the second electrode of the organic light emitting diode according to the fifth exemplary embodiment of the present invention to have a thickness of 800 kPa to 1200 kPa.
13 is a cross-sectional view of a portion of a display area of an organic light emitting diode according to a sixth exemplary embodiment of the present invention.
14 is a cross-sectional view of a part of a display area of an organic light emitting diode according to a modification of the sixth exemplary embodiment of the present invention.

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

First, the configuration and operation of the organic light emitting diode will be briefly described with reference to FIG. 1, which is a circuit diagram of one pixel of the organic light emitting diode.

As illustrated, one pixel of the organic light emitting diode 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. have.

That is, the gate line GL is formed in the first direction, the pixel region P is defined in the second direction crossing the first direction, and the data line DL is formed. And a power supply wiring (PL) for applying a power supply voltage is spaced apart.

In addition, a switching thin film transistor STr is formed at a portion where the data line DL and the gate wiring GL cross, 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, which is the other terminal, is grounded. In this case, the power line PL transfers a power supply voltage to the organic light emitting diode E. In addition, 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 transferred to the gate electrode of the driving thin film transistor DTr to drive the driving signal. Since the thin film transistor DTr is turned on, light is output through the organic light emitting diode E. At this time, when the driving thin film transistor DTr is in an on state, the level of the current flowing from the power supply line PL to the organic light emitting diode E is determined, and thus, the organic light emitting diode E The gray scale may be implemented, and the storage capacitor StgC maintains the gate voltage of the driving thin film transistor DTr constant when the switching thin film transistor STr is turned off. By doing so, even if the switching thin film transistor STr is in an off state, the level of the current flowing through the organic light emitting diode E can be kept constant until the next frame.

2 is a cross-sectional view of a part of a display area of an organic light emitting diode according to a first exemplary embodiment of the present invention. In this case, for convenience of description, the region in which the driving thin film transistor DTr is formed is the driving region DA, and the region in which the switching thin film transistor is formed in each pixel region P is not shown in the figure. This is defined as.

As illustrated, the organic light emitting diode 101 according to the first embodiment of the present invention may include a first substrate 110 having a driving and switching thin film transistor DTr (not shown) and an organic light emitting diode E formed thereon; It is composed of a second substrate 170 for encapsulation. In this case, the second substrate 170 may be omitted by being replaced with an inorganic film or an organic film.

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

The driving area DA and the switching area of the first substrate 110 are made of pure polysilicon, respectively, and a central part thereof is formed on both sides of the first area 113a and the first area 113a that form a channel passage. The semiconductor layer 113 including the second region 113b doped with a high concentration of impurities is formed.

In this case, a buffer layer (not shown) made of an inorganic insulating material, for example, silicon oxide (SiO ₂ ) or silicon nitride (SiNx) may be further provided between the semiconductor layer 113 and the first substrate 110. It may be. The buffer layer (not shown) is to prevent 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.

In addition, a gate insulating layer 116 is formed on the entire surface of the semiconductor layer 113, and the semiconductor layer 113 is disposed in the driving area DA and the switching area (not shown) on the gate insulating layer 116. The gate electrode 120 is formed to correspond to the first region 113a of FIG. 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, for example, silicon oxide (SiO ₂ ) or silicon nitride (SiNx), is formed on the gate electrode 120 and the gate wiring (not shown). In this case, the interlayer insulating layer 123 and the gate insulating layer 116 below are provided with a semiconductor layer contact hole 125 that exposes the second region 113b located on both sides of the first region 113a, respectively. .

Next, an upper portion of the interlayer insulating layer 123 including the semiconductor layer contact hole 125 may be spaced apart from a data line (not shown) that crosses the gate line (not shown) and defines a pixel area P. Power wirings (not shown) are formed side by side.

In addition, the driving area DA and the switching area (not shown) are spaced apart from each other on the interlayer insulating layer 123 and contact the second area 113b exposed through the semiconductor layer contact hole 125, respectively. Drain electrodes 133 and 136 are formed.

The source and drain electrodes 133 and 136 spaced apart from the semiconductor layer 113, the gate insulating layer 116, the gate electrode 120, and the interlayer insulating layer 123 sequentially stacked in the driving region DA may be formed. A driving thin film transistor DTr is formed. In this case, a switching thin film transistor (not shown) having the same structure as the driving thin film transistor DTr formed in the driving area DA is also formed in the switching area (not shown).

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

Meanwhile, the driving and switching thin film transistor DTr (not shown) may form a p-type or n-type thin film transistor according to impurities doped in the second region 113b. In the case of a p-type thin film transistor, a third group element, for example, boron (B), is doped in the second region 113b. In the case of an n-type thin film transistor, a group 5 is formed in the second region 113b. This is done by doping an element, for example phosphorus (P).

The p-type thin film transistor uses holes as a carrier, and the n-type thin film transistor uses electrons as a carrier. Therefore, the first electrode 147 connected to the drain electrode 136 of the driving thin film transistor DTr serves as an anode or a cathode according to 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 n type, the first electrode 147 serves as a cathode electrode.

In the first exemplary embodiment of the present invention, the driving thin film transistor DTr forms the p-type, and thus, the first electrode 147 serves as an anode.

Next, a passivation layer 140 having a drain contact hole 143 exposing the drain electrode 136 of the driving thin film transistor DTr is formed on the driving and switching thin film transistor DTr (not shown). In this case, the protective layer 140 is made of an organic insulating material, for example, photo acryl or benzocyclobutene (BCB) to achieve a flat surface with little effect on the step of the lower component. .

In addition, the protective layer 140 is in contact with the drain electrode 136 and the drain contact hole 143 of the driving thin film transistor DTr, and has a high work function value for each pixel area P. A first electrode 147 is formed of a material, for example indium-tin-oxide (ITO).

In this case, the first electrode 147 may have a single layer structure made of only the above-described transparent conductive material, or may be formed of aluminum, which is a metal material having excellent reflectance to increase the luminous efficiency of the organic light emitting diode E. The first layer 147a made of any one of Al), aluminum alloy (AlNd), and silver (Ag) and the second layer 147b made of a metal material having a high work function value may be formed.

Next, as described above, the bank 150 overlaps the edge of the first electrode 147 having a single layer or double layer structure and serves as an anode electrode, and overlaps each pixel region P on the passivation layer 140. ) Is formed.

The organic emission layer 155 is formed on the first electrode 147 in each pixel region P surrounded by the bank 150. In this case, the organic light emitting layer 155 may be composed of a single layer made of an organic light emitting material, or a hole injection layer sequentially from the upper portion of the first electrode 147 serving as the anode electrode to improve the light emitting efficiency hole injection layer 155a, hole transporting layer 155b, organic emitting material layer 155c, electron transporting layer 155d, and electron injection layer It may be formed of multiple layers of the layer 155e. In the drawing, the organic light emitting layer 155 has a five-layer structure as an example.

Next, in the first embodiment of the present invention, the second electrode having a double layer structure having a double layer structure on the organic light emitting layer 155 and the bank 150 serves as a cathode on the entire display area. 158 is 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).

Meanwhile, referring to the structure of the second electrode 158 having a double layer structure, the lower layer 158a may be formed of a metal material having a low work function value, for example, silver (Ag), magnesium-silver alloy (Mg: Ag), It consists of any one of gold (Au), magnesium (Mg), copper (Cu) and calcium (Ca), the thickness of which is formed to have a thickness of about 50 to 200 Å to maintain the light transmittance of 15% or more. It is characteristic that there is.

In addition, the upper layer 158b of the second electrode 158 is formed of any one of indium-zinc-oxide (ITO) or indium-tin-oxide (ITO), which is a transparent conductive material, and has a thickness of about 50 kPa to 1000 kPa. Is characteristic.

The second electrode 158 having such a double layer structure is formed so that the lower layer 158a made of a metal material having a low work function value has a thickness of about 10 kPa to about 200 kPa, so that its sheet resistance is increased to be a transparent conductive material thereon. As the upper layer 158b is formed to have a thickness of about 50 kPa to about 1000 kPa, the thickness of the second electrode 158 itself increases as a whole, thereby reducing the sheet resistance.

Table 1 shows an organic compound according to a first 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 and a second electrode having a double layer structure. The second electrode of the electroluminescent device shows the transmittance of light in a specific wavelength band in a state of having a similar level of sheet resistance.

Monolayer (MgAg) Bilayer (MgAg + IZO) Sheet resistance (Ω / □) 9.9 (Ω / □) 10.5 (Ω / □) Permeability (%) 470nm wavelength light 15.8% 42.6% 550nm wavelength light 11.9% 32.5% 630nm wavelength light 9.2% 22%

Referring to Table 1, when the sheet resistance of the second electrode is set to a similar level that can operate as the organic light emitting device in the organic light emitting device according to the comparative example and the first embodiment of the present invention, In the comparative example of the monolayer structure of the magnesium-silver alloy (Mg: Ag), the transmittance of the light having the wavelength range of 470 nm, 550 nm, and 630 nm was 15.8%, 11.9%, and 9.2%, while the second electrode was magnesium In the case of the first embodiment of the present invention having a double layer structure of a lower layer of silver alloy (Mg: Ag) and an upper layer of indium-zinc-oxide (IZO), each transmittance for light having a wavelength range of 470 nm, 550 nm, and 630 nm is By 42.3%, 32.5%, and 22%, it can be seen that the first embodiment according to the present invention has improved luminance characteristics by more than twice as compared with the comparative example.

Table 2 shows an organic compound according to the first 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 and a second electrode having a double layer structure. In the electroluminescent device, the light transmittance of each wavelength band is shown when the magnesium-silver alloy (Mg: Ag) has the same thickness.

Permeability (%) Monolayer (MgAg) Bilayer (MgAg + IZO) 470nm wavelength light 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 light emitting device according to the comparative example and the first embodiment of the present invention, the light transmittance of each wavelength band when the portion made of magnesium-silver alloy (Mg: Ag) has the same thickness is shown. In comparison, in the case of the comparative example in which the second electrode forms a single layer structure of magnesium-silver alloy (Mg: Ag), the transmittances of the light having wavelengths of 470 nm, 550 nm, and 630 nm were 10.5%, 7.9%, and 6.3%. While the second electrode has a double layer structure of a lower layer of magnesium-silver alloy (Mg: Ag) and an upper layer of indium-zinc-oxide (IZO), the second electrode has a wavelength band of 470 nm, 550 nm, and 630 nm. It can be seen that the transmittance of each light is 26.1%, 18.4%, and 12.4%.

Therefore, even if the second electrode made of magnesium-silver alloy (Mg: Ag) of the same thickness is configured, the organic light emitting device according to the present invention has a structure in which an upper layer made of indium-zinc-oxide is further provided thereon. It can be seen that the properties have more than two times more improved in terms of transmittance.

This improvement in the transmittance of the bilayer structure made of different materials rather than the single layer structure may be due to the micro cavity effect by the optical length control.

The micro-cavity effect is a reflection of light inside a specific material layer. If a specific condition is satisfied, the light transmission efficiency can be improved by reflecting it at a time. In order to realize such micro-cavity effect, a double-layer structure having different reflectances is used. Should be done.

3 is a cross-sectional view of a part of the display area of the organic light emitting device according to the modification of the first embodiment of the present invention. As shown in the same reference numerals), the second electrode 158 is a metal material having a low work function value such as silver (Ag), magnesium-silver alloy (Mg: Ag), and gold (Au). It may be made of a single layer structure consisting of any one of, in this case, the inorganic layer made of a transparent inorganic oxide, for example, silicon oxide (SiO 2) or aluminum oxide (Al ₂ O ₃ ) on the second electrode 158 of the single layer structure The 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.

In the organic light emitting device 101 according to the modified example of the present invention having the above configuration, the second electrode 158 of the conventional single layer structure is formed, and a comparative example in which an inorganic insulating film or an organic insulating film is not formed thereon. In comparison with the organic light emitting device according to the characteristics of the light transmission characteristics are improved.

In the case of the organic light emitting device 101 according to the above-described modification, 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 on the upper part thereof in contact with the second electrode 158 of the single layer, and surface plasmon is generated by this configuration. The transmittance of light generated from the light emitting layer 155 may be improved.

Surface plasmons are collective charge density oscillations of electrons that occur at the surface of a metal thin film, and these surface plasmons occur in certain metals, that is, the electrons are easily released by external stimuli and have negative dielectric constants. The metal that generates surface plasmons is, for example, gold (Au), silver (Ag), and the like.

Plasmon has a characteristic that when light is incident from the outside, it moves in a group, and when light satisfying a specific condition is incident, it emits stronger light in response to it, and the transmittance of light is improved by the characteristics of the surface plasmon. there was.

On the other hand, in the case of the organic light emitting device 101 according to the modification of the first embodiment of the present invention described above, the low-resistance characteristics of the second electrode 158 itself having a single layer structure of a metal material having a low work function value Although the thickness of the second electrode 158 itself is thicker than that of the comparative example, the thickness of the second electrode 158 is increased by increasing the transmittance relative to the comparative example so that the transmittance is the same as that of the comparative example. Can be lowered. Therefore, the organic light emitting device 101 according to the modified example of the present invention also has an effect of improving luminance characteristics or reducing power consumption by increasing the transmittance.

Meanwhile, referring to FIGS. 2 and 3, a second substrate for encapsulation corresponding to the first substrate 110 of the organic light emitting device 101 according to the first embodiment or modified example having the above-described configuration. 170 is spaced apart from the first substrate 110. At this time, the first substrate 110 and the second substrate 170 is provided with an adhesive (not shown) made of a sealant or frit along the edge, the first substrate 110 by such an adhesive (not shown) ) And the second substrate 170 are bonded to each other to maintain the panel state.

The first substrate 110 and the second substrate 170 spaced apart from each other have a vacuum atmosphere or are filled with an inert gas to form an inert gas atmosphere.

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

Meanwhile, the organic light emitting diode 101 according to the first embodiment and the modification described above is provided with a second substrate 170 for encapsulation in a form 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 light emitting device 101 according to the modification of the first embodiment of the present invention, an organic insulating film (not shown) or an inorganic layer is disposed on the second electrode 158 of the single layer structure. When the insulating film 162 is formed, the organic insulating film (not shown) or the inorganic insulating film 162 is used as an encapsulation film by itself, in which case the second substrate 170 may be omitted.

4 shows 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 the second electrode has a magnesium-silver alloy single layer structure, on which an organic or inorganic insulating film is formed. The organic light emitting diode according to the modified example of the first embodiment of the present invention and the organic electroluminescent device according to the comparative example including the second electrode of the magnesium-silver alloy single layer structure is a graph showing the transmittance for each wavelength. In this case, in the comparative example, the transmittance of the second electrode having the single-layer structure of the magnesium-silver alloy was formed to have a thickness of 150 kPa and 240 kPa, respectively, and in the case of the first embodiment and the modified example, a portion made of magnesium-silver alloy The transmittance of light to the one having a thickness of 240 Hz is shown.

Referring to the drawings, in the case of a comparative example (hereinafter referred to as a first comparative example) having a first embodiment and a modified example of the present invention and a second electrode made of a magnesium-silver alloy having a thickness of about 150 μs, red, green, It can be seen that each of the wavelengths of 470nm to 630nm emitting blue light has transmittances of 26% to 34% (first embodiment), 25% to 36% (variant), and 26% to 36%, respectively. In the case of a comparative example (hereinafter referred to as a second comparative example) having a second electrode made of a magnesium-silver alloy having a thickness of about a degree, its transmittance was significantly lower than that of the first comparative example, the first example, and the modified example, 11%. It can be seen that it has a transmittance of 18% to 18%.

Particularly, the light of the wavelength range of 550 nm displaying green has 33% transmittance in the first embodiment, the modified example, and the first comparative example, but has a transmittance of 14% in the second comparative example. Able to know.

In the comparative example, when the thickness of the second electrode made of only magnesium-silver alloy is reduced to 200 μs or less, it can be used as a display device by having an average transmittance of about 15%, but in this case, the sheet resistance of the second electrode is increased. There is a problem of increasing power consumption, and as shown in the second comparative example, when the second electrode made of only magnesium-silver alloy has a thickness of about 240 kW, for example, a thickness larger than 200 kW, the sheet resistance may be lowered. As can be seen that the average transmittance for light in the wavelength range of 470nm to 630nm is less than 15%.

However, in the case of the first embodiment and the modified example of the present invention, even if the thickness of the portion of the magnesium-silver alloy is 200 Å or more, for example, about 240 Å, the transmittance for light in the wavelength range of 470 nm to 630 nm is 30% or more on average. Can be.

Therefore, in view of these experimental results, the organic light emitting diode according to the first embodiment and the modification 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. It will have a remarkable effect compared to the organic light emitting device according to the first and second comparative examples.

FIG. 5 is a cross-sectional view of one pixel area of the organic light emitting diode according to the second embodiment of the present invention. Since the same components are assigned the same reference numerals as in the first embodiment, and the same reference numerals as those in the first embodiment are assigned only to the second electrodes having different points.

The most characteristic feature of the organic light emitting 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 a metal material having a relatively low work function, silver (Ag), magnesium-silver alloy (Mg: 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; The fourth layer 259c made of the same material forming the third layer 259b made of any one of silver (Ag), gold (Au), and copper (Cu) and the second layer 259a described above. It is characterized by forming a quadruple structure.

In this case, the first layer 258 has a thickness of about 10 kPa to about 50 kPa, and the total thickness of the triple layer consisting of the second to fourth layers 259a to 259c is about 400 kPa to about 1000 kPa, and the double low resistance The third layer 259b made of a metal material has a thickness of about 150 kPa to about 300 kPa.

Thus, 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 micro cavity effect more than the first embodiment to increase the light transmittance and lower the sheet resistance.

In the organic light emitting device 101 according to the second exemplary embodiment of the present invention, two layers of the first layer 258 and the third layer 259b are capable of reflecting light in the second electrode 257. Since the layer becomes a layer, the micro-cavity effect can be increased as compared with the first embodiment in which the layer reflected in the second electrode 257 has only one lower layer.

Therefore, by increasing the micro-cavity effect, the transmittance is improved, so that the overall thickness of the second electrode 257 can be relatively thick, thereby improving the low resistance property, thereby reducing the sheet resistance.

In the case of the organic light emitting device 101 including the second electrode 257 having a quad layer structure according to the second embodiment of the present invention, the sheet resistance of the second electrode 257 itself is 1.9 kW / □ to 5 kW /. □, and having a transmittance of 50% or more for light of red, green, and blue wavelength bands, respectively, it was found to be more excellent in reducing sheet resistance and improving transmittance than in the first embodiment, including the comparative example described above.

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

Comparative Example: Single Layer (MgAg) Example 2 Quadruple Layer (MgAg + IZO + Ag + IZO) Sheet resistance (Ω / □) 9.9 (Ω / □) 1.9 (Ω / □)
Permeability (%)
470nm wavelength light 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 with 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 Ω / □, 470nm, 550nm , The transmittance of light having a wavelength range of 630 nm is 15.8%, 11.9%, and 9.2%.

Whereas the first layer of magnesium-silver alloy (Mg: Ag) (258 in FIG. 5) and the second layer of indium-zinc-oxide (IZO) (259a in FIG. 5) and the third layer of silver (Ag) For a second embodiment of the invention with a second electrode (257 of FIG. 5) having a quadruple structure of 259b of 5) and a fourth layer of indium-zinc oxide (IZO) (259c of FIG. 5), Even when the first to fourth layers (258 to 259c in FIG. 5) are formed to have an appropriate thickness so that the sheet resistance is about 1.9 GPa / square, each transmittance of light having a wavelength range of 470 nm, 550 nm, or 630 nm It can be seen that the 73.7%, 73.1%, 54.9%.

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

Furthermore, in comparison with the first embodiment of the present invention having the second embodiment of the present invention and the second electrode of the double layer structure (158 of FIG. 2), referring to Tables 1 and 3, the second of the four layer structure It can be seen that the second embodiment of the present invention having the electrode (257 of FIG. 5) is more excellent in terms of sheet resistance reduction than the first embodiment, and is improved by 1.3 to 2 times in terms of transmittance.

FIG. 6 is a graph showing wavelength-specific transmittance of an organic light emitting diode according to a second exemplary embodiment of the present invention in which the second electrode has a quad layer structure and a 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 the single layer structure of the magnesium-silver alloy was formed to have a thickness of 140 kPa was shown. In the second embodiment, the first layer made of the magnesium-silver alloy was 10 kPa, indium. The second and fourth layers of zinc oxide (IZO) each have a thickness of 400 kPa, the third layer of silver (Ag) having a thickness of 240 kPa (denoted as 'Example 2-1' in the drawing), magnesium The first layer of silver alloy is 10 kPa, the second and fourth layer of indium zinc oxide (IZO) is 400 kPa, respectively, and the third layer of silver (Ag) has a thickness of 300 kPa (' Permeability of light) is shown for Example 2-2 '.

Referring to the drawings, the second embodiment of the present invention having a quadruple electrode having a second layer has a transmittance of about 54% to 73% for light in the wavelength range of 470 nm to 630 nm emitting red, green, and blue light. It can be seen.

However, it can be seen that the comparative example including the second electrode having a single layer structure made of magnesium-silver alloy has a transmittance of 26% to 36% for light in the wavelength range of 470 nm to 630 nm emitting red, green, and blue light. .

Accordingly, it can be seen that the organic light emitting diode according to the second exemplary embodiment of the present invention having the quadruple structure in terms of transmittance is superior to the comparative example having the second electrode having a single layer structure.

On the other hand, in recent years, the display device has become large in size, and therefore, the sheet resistance of the second electrode formed in the form of a plate over the entire display area is a big issue. As the area becomes larger, the area term of the second electrode may be smaller to provide a display device having excellent display quality without errors in the center and side surfaces of the display area.

Therefore, there is a demand for a technique in which the sheet resistance of the second electrode formed in the shape of a plate on the entire display area in the organic electroluminescent device is set to 2 dB / square or less, preferably 1 dB / square, while the transmittance is 30% or more. It's happening.

In accordance with this demand, the third embodiment of the present invention provides an organic light emitting device in which a second electrode having a sheet resistance of 2 μs / square or less is implemented.

FIG. 7 is a cross-sectional view of one pixel area of the organic light emitting diode according to the third embodiment of the present invention, and all components formed below the structure of the second electrode are the same as those of the above-described second embodiment. Only the 2nd electrode with which this was enlarged was shown (only the part shown by area | region A of FIG. 5 is shown).

The third embodiment of the present invention has a second electrode 357 having a sheet resistance of 2 kW / square or less while serving as a cathode, and having an organic electroluminescence having a transmittance of 30% or more for light in the red, green, and blue wavelength bands. It is characterized by the implementation of the device.

The most characteristic of the organic light emitting device (not shown) according to the third embodiment of the present invention is that the second electrode 357 has a more multilayer structure than the first embodiment to maximize the micro cavity effect. It is a structure.

That is, the second electrode 357 according to the third embodiment of the present invention is a metal material having a relatively low work function, silver (Ag), magnesium-silver alloy (Mg: Ag), gold, to serve as a cathode electrode. A first layer 358 made of any one of (Au), magnesium (Mg), copper (Cu), and calcium (Ca), and 3 embodied in the first embodiment above the first layer 358. The second layer 359a composed of an indium-tin-oxide or indium-zinc-oxide, which is a transparent conductive material, and silver (Ag), gold (Au), and copper (Cu), which are low-resistance metal materials, In addition to the configuration of the fourth layer 359c made of the same material constituting the third layer 359b and the second layer 359a described above (hereinafter, the triple layer is defined as the set layer 359). The set layer 360 (360a, 360b, 360c) consisting of three layers on the fourth layer 359c is once again constituted. Thus, according to the third embodiment of the present invention, The second electrode 357 is characterized by forming a total of seven layers.

 In the drawing, in the case of the organic light emitting diode (not shown) according to the third embodiment of the present invention, the second electrode 357 is formed of the first layer 358 and the first and second set layers 359 and 360. Although it is shown as an example of a total seven-layer structure, but as a modification of the third embodiment of the present invention another one or more set layer (not shown) is further provided over the second set layer 10 or 13 layer structure It can also be

In such a configuration, the layer in which light is reflected in the second electrode 357 is further increased, thereby maximizing the micro cavity effect. Therefore, the light transmittance is improved. As a result, even if the number of layers of the low resistance material among the plurality of layers constituting the second electrode 357 is increased, the transmittance is not lowered. Thus, the sheet resistance of the entire second electrode 357 is reduced. Can be lowered.

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

8 shows a third embodiment of the invention with a second electrode with a six layer of IZO / Ag / IZO / IZO / Ag / IZO over a first layer of magnesium-silver alloy (Mg: Ag) and IZO / First embodiment of the present invention with a triple layer of Ag / IZO and a first comparative example with a layer made of Ag over a first layer of magnesium-silver alloy (Mg: Ag) and IZO / Ag / IZO / Ag A graph showing transmittance of wavelengths of organic light emitting diodes according to a second comparative example having a second electrode provided with a 5-layer of / IZO. At this time, in the examples and comparative examples, the layer made of silver (Ag) was formed in a thickness of 250 kPa and the layer made of IZO all 400 kPa.

As shown, it can be seen that the second and third embodiments of the present invention have a transmittance of 30% or more for each of light in the wavelength range of 470 nm to 600 nm that emits red, green, and blue light.

However, in the first comparative example, in which the second layer of silver (Ag) is provided over the first layer of the magnesium-silver alloy (Mg: Ag), the light in the wavelength range of 470 nm to 600 nm, particularly in light having the wavelength range of 600 nm It can be seen that it has a transmittance of less than 30%. For the second comparative example in which the quinine layer of IZO / Ag / IZO / Ag / IZO is provided on the first layer of magnesium-silver alloy (Mg: Ag), red, It can be seen that among the light in the wavelength range of 470 nm to 600 nm that emits green and blue, the transmittance of 20% or less is observed for light in the wavelength range of 530 nm or more.

As a result, it can be seen that in the third embodiment of the present invention, since the layer of silver (Ag) is provided with two layers as an example of the low resistance material, the sheet resistance can be relatively reduced. When the third layer and the sixth layer made of silver (Ag) have a thickness of 250 kPa, the sheet resistance of the entire second electrode having a seven-layer structure becomes about 1 kW / square, thereby inducing the organic according to the third embodiment of the present invention. It can be seen that the electroluminescent device is superior to the comparative examples and the first and second embodiments in terms of reducing sheet resistance.

FIG. 9 is a cross-sectional view of three pixel areas emitting continuous red, green, and blue light, respectively, of the organic light emitting diode according to the fourth exemplary embodiment of the present invention. Is the same as the above-described second embodiment, and is mainly focused on the second electrode having different points. For convenience of description, the pixel areas emitting red, green, and blue light are defined as first, second, and third pixel areas P1, P2, and P3, respectively.

As shown, organic light emitting layers 455 (455a, 455b, and 455c) having the same thickness and emitting red, green, and blue colors are formed in the first, second, and third pixel areas P1, P2, and P3, respectively. . In the drawing, although the organic light emitting layers 455a, 455b, and 455c emitting red, green, and blue light are shown as being in contact with each other, substantially boundaries of the first, second, and third pixel areas P1, P2, and P3 are shown. Banks (not shown) are formed in the first and second red, green, and blue organic light emitting layers 455a and 455b by separating the first, second, and third pixel areas P1, P2, and P3 by the banks (not shown). , 455c is formed separately.

Next, on the red, green, and blue organic light emitting layers 455a, 455b, and 455c, the second electrode 457 is formed on the entire display area without separation between the pixel areas P1, P2, and P3.

In this case, the second electrode 457 is a metal material having a relatively low work function (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg) to function as a cathode electrode , A first layer 461 made of any one of copper (Cu) and calcium (Ca), and an indium tin oxide or indium zinc oxide, which is a transparent conductive material on the first layer 461. A second layer 462 formed of a low resistance metal material, a third layer 463 made of any one of silver (Ag), gold (Au), and copper (Cu), and the second layer 462 described above. A fifth layer 465 made of the same material forming the fourth layer 464 (464a, 464b, 464c) made of the same material and the third layer 463, and the same material forming the second layer 462. The sixth layer 466 is composed of a six-layer structure.

In this case, the most distinctive feature of the fourth embodiment of the present invention is that the fourth layer 464 made of the transparent conductive material has a different thickness for each of the first, second, and third pixel regions P1, P2, and P3. It is becoming. 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 areas P1, P2, and P3. Each of the fourth layers 464 has the same thickness, but the fourth layer 464 has a different thickness for each of the first, second, and third pixel areas P1, P2, and P3.

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

In this case, the fourth layer 464 preferably has a thickness of about 400 kPa to 1200 kPa.

Meanwhile, the first layer 461 has a thickness of about 10 kPa to about 50 kPa, and the total thickness of the fifth layer consisting of the second to sixth layers 462, 463, 464, 465, and 466 is about 1000 kPa to 2500 kPa. The thickness of the third layer 463 and the fifth layer 465 made of a double low resistance metal material is preferably about 150 kPa to about 400 kPa.

The fourth layer 464 made of the transparent conductive material may be formed for each of the first, second, and third pixel areas P1, P2, and P3 having the organic light emitting layers 455a, 455b, and 455c that emit red, green, and blue light, respectively. Forming to have a different thickness improves the transmittance of the emitted light in all of the first, second, and third pixel regions P1, P2, and P3, and further increases the surface resistance of the second electrode 457 to 1 kW /? To 3 kW /. □ To achieve the level.

In the case of forming a layer made of a transparent conductive material, respectively, above and below a layer made of a low resistance metal material having the same thickness, the transmittance is improved.

However, when the thickness of the layer of the low-resistance metal material is formed to have a thickness greater than 400 kV so that the sheet resistance level of the second electrode 457 is about 1 kV / □ to 3 kV / □, upper light emission is low. It cannot be used as the second electrode of the organic electroluminescent device of the type.

In order to solve this problem, the second to fifth layers 462, 463, 464, 465, and 466 except for the first layer 461 are IZO / Ag, for example, without thickness difference for each pixel region P1, P2, and P3. If formed to have a structure of / IZO / Ag / IZO, the micro-cavity effect can be maximized, so that transmittance compensation occurs and the overall transmittance is improved, but red or blue light is emitted other than the second pixel area P2 that emits green light. The transmittance in the first and third pixel regions P1 and P2 is lowered.

Therefore, in order to suppress the decrease in the transmittance in the first and third pixel areas P1 and P3 emitting red and blue light, the fourth made of a transparent conductive material in consideration of the wavelength band of the light emitting red, green, and blue light. The thickness of the layer 464 is differently formed for each of the first, second, and third pixel areas P1, P2, and P3.

The organic light emitting diode according to the fourth exemplary embodiment of the present invention having such a constitutional feature may be formed even when the thickness of the third layer 463 and the fifth layer 465 made of a low resistance metal material is about 300 kPa to about 400 kPa. In terms of transmittance, the second to fifth layers 462, 463, 464, 465, and 466 have an organic structure of IZO / Ag / IZO / Ag / IZO without thickness difference for each pixel region P1, P2, and P3. It is characterized by being at a level similar to the transmittance of the EL device.

Therefore, the organic light emitting diode according to the fourth exemplary embodiment of the present invention can form the thicknesses of the third and fifth layers 463 and 465 made of low-resistance metal materials up to 400 kW while maintaining a certain level of transmittance. Therefore, the surface resistance of the second electrode 457 itself can be maintained at a low level of about 1 kW / □ to 3 kW / □, which is advantageous in that it is advantageous in large area.

10 is a graph measuring transmittance while changing the thickness of the fourth layer of the second electrode of the organic light emitting device according to the fourth embodiment of the present invention to have a thickness of 600 kPa to 1000 kPa. In this case, in addition to the first layer serving as the cathode as the first comparative example, only the second layer having a thickness of 250 μs of silver (Ag) is provided, and as the second comparative example, the second to fourth layers are IZO 400 μs / Ag 250 μs. The transmittances of the structure having the structure of / IZO 400 Pa and the second to sixth layers having the structure of IZO 400 Pa / Ag 250 Pa / IZO 400 Pa / Ag 250 Pa / IZO 400 Pa are also shown as the third comparative example.

As shown in the figure, when the fourth layer is formed to have a thickness of 600 Hz, 800 Hz, 1000 Hz, respectively, it can be seen that peak values of 0.66, 0.66, 0.58 are achieved in the wavelength bands of blue, green, and red, respectively.

Therefore, the first layer of light emitting green, green, and blue light emitting materials may be formed to vary the thickness of the fourth layer for each of the first, second, and third pixel areas. The final sum total transmittance is 0.5 or more by forming a thickness of about 800 GPa in the two pixel region and a thickness of about 600 GPa in the third pixel region emitting blue light.

However, in the first, second, and third comparative examples, it can be seen that all have a transmittance of 0.4 or less in the wavelength range of 470 nm to 650 nm representing red, green, and blue.

FIG. 11 is a cross-sectional view of three pixel areas emitting continuous red, green, and blue light, respectively, of the organic light emitting diode according to the fifth embodiment of the present invention. Is the same as the above-described second embodiment, and is mainly focused on the second electrode having different points. For convenience of description, the pixel areas emitting red, green, and blue light are defined as first, second, and third pixel areas P1, P2, and P3, respectively.

As illustrated, organic light emitting layers 555 (555a, 555b, and 555c) having the same thickness and emitting red, green, and blue colors are formed in the first, second, and third pixel areas P1, P2, and P3, respectively. . In the drawing, 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, the boundary of each of the first, second, and third pixel areas P1, P2, and P3 is substantially shown. Banks (not shown) are formed therein, and thus the first, second, and third pixel areas P1, P2, and P3 are separated by the banks (not shown), thereby forming the red, green, and blue organic light emitting layers 555a and 555b. 555c is separately formed.

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

At this time, the second electrode 557 is a metal material having a relatively low work function value to act as a cathode electrode, silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg) , A first layer 561 made of any one of copper (Cu) and calcium (Ca), and an indium tin oxide or indium zinc oxide, which is a transparent conductive material on the first layer 561. A second layer 562 made of a material, a third layer 563 made of any one of silver (Ag), gold (Au), and copper (Cu), which are low-resistance metal materials, and an organic material, for example, a material forming a protective layer. The fourth layer 564 (564a, 564b, 564c) made of phosphorous benzocyclobutene or photoacryl or the material forming the organic light emitting layer and the fifth layer 565 made of the same material forming the third layer 563; The sixth layer 566 is formed of a six-layer structure made of the same material constituting the second layer 562.

In this case, the most distinctive feature of the fifth embodiment of the present invention is that the fourth layer 564 made of the organic material is spaced apart from each other by the first, second, and third pixel areas P1, P2, and P3, and has different thicknesses. And the third layer 563 and the fifth layer 565 made of a low resistance metal material on the lower part and the upper part with the fourth layer 564 interposed therebetween, respectively. In the boundary of P3), that is, the spaced area between the fourth layers 564a, 564b, and 564c, which are spaced from each other, they are formed in contact with each other.

In this case, the fourth layers 564a, 564b, and 564c, which are formed by separating the first, second, and third pixel regions P1, P2, and P3, having different thicknesses, may emit red light having a relatively long wavelength ( The portion corresponding to the first pixel region P1 having the 555a has the thickest first thickness and corresponds to the third pixel region P3 having the organic emission layer 555c emitting the shortest blue color. The second portion has the thinnest second thickness, and the portion corresponding to the second pixel region in which the green organic light emitting layer is provided has a third thickness thinner than the first thickness and thicker than the second thickness.

At this time, it is preferable that the fourth layer 564 has a thickness of about 400 kPa to about 1200 kPa.

Meanwhile, the first layer 561 has a thickness of about 10 kPa to about 50 kPa, and the total thickness of the fifth layer consisting of the second to sixth layers 562, 563, 564, 565, and 566 is about 1000 kPa to 2500 kPa. The thickness of the third layer 563 and the fifth layer 565 made of a double low resistance metal material is preferably about 150 kPa to about 400 kPa.

In this way, the fourth layer 564 made of the organic material is different for each of the first, second, and third pixel areas P1, P2, and P3 provided with the organic emission layers 555a, 555b, and 555c that emit red, green, and blue light. Forming to have a thickness improves the transmittance of the emitted light in all of the first, second, and third pixel areas P1, P2, and P3, as described with reference to the fourth embodiment. The thickness of the fifth layer 565 is about 400 GPa, so that the surface resistance of the second electrode 557 is about 1 kV / □ to 3 kV / □.

The organic light emitting diode according to the fifth embodiment of the present invention having such a configuration also overlaps with the fourth layer 564 in the third layer 563 and the fifth layer 565 made of a low resistance metal material. Even if the thickness of the portion is set to about 300 to 400 mm, respectively, the second to fifth layers 562, 563, 564, 565, and 566 have no thickness difference for each pixel area P1, P2, and P3 in terms of transmittance. The organic electroluminescent device having the structure of IZO / Ag / IZO / Ag / IZO has a level similar to that of the transmittance.

Accordingly, the organic light emitting diode according to the fifth exemplary embodiment of the present invention maintains a level of transmittance while the fourth layer 564 of the third layer 563 and the fifth layer 565 made of a low resistance metal material. Since the thickness of the overlapping portion can be formed up to about 400 kPa, the sheet resistance of the second electrode 557 itself can be maintained at a low level of about 1 kPa / square to 3 kPa / square, which is advantageous for large area.

12 is a graph measuring transmittance while changing the thickness of the fourth layer of the second electrode of the organic light emitting device according to the fifth embodiment of the present invention to have a thickness of 800 kPa to 1200 kPa. In this case, in addition to the first layer serving as the cathode as the first comparative example, the second to fourth layers have the configuration of IZO 400 Å / Ag 250 Å / IZO 400 Å, and as the second comparative example, the second to sixth layers IZO 400 Å / Ag 250 Å / IZO 800 Å / Ag 250 Å / IZO 400 Å and the second to sixth layers as the second comparative example as the third embodiment are IZO 400 Å / Ag 250 Å / IZO 400 Å / Ag 250 Å / Also shown is the transmittance of the organic light emitting device constituting the IZO 400 kHz.

As shown, when the fourth layer is formed as an organic material with an thickness of, for example, 800 kPa, 1000 kPa, and 1200 kPa, the transmittances of 0.78, 0.7, and It can be seen that the peak value is about 0.68.

Accordingly, the thickness of the fourth layer may be different for each of the first, second, and third pixel areas P1, P2, and P3 that emit red, green, and blue colors, that is, the thickness of about 1200 μs in the first pixel area that emits red light. It can be seen that the final summed transmittance is 0.58 or more by forming a thickness of about 1000 mW in the second pixel area emitting green light and having a thickness of about 800 mW in the third pixel area emitting blue light.

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 the second embodiment has a transmittance of about 0.4 in the wavelength range of 470 nm to 600 nm. In the case of the example it can be seen that having a transmittance of about 0.1 to 0.3 in the wavelength range of 470nm to 600nm.

Therefore, in the case of the fifth embodiment of the present invention, since the average transmittance is 0.58 or more, it is understood that the second electrode is the transmittance level of the first comparative example having a total quad layer structure including the first layer serving as the cathode electrode. It can be seen that the transmittance is much better than the transmittance of the third comparative example having a total of six-layer structure.

13 and 14 are cross-sectional views of a portion of a display area of an organic light emitting diode according to a sixth embodiment and a sixth embodiment of the present invention, respectively. For example, the second electrode has a quad layer structure. An encapsulation film having a quad layer structure is provided on the second electrode of the organic light emitting diode according to the second embodiment. For the convenience of description, the same components shown in the second embodiment are the same drawings. Signed.

At this time, the most characteristic of the organic light emitting device according to the sixth embodiment of the present invention and its modification is in the encapsulation film for encapsulation formed on the second electrode, the lower portion of the encapsulation film Among the organic light emitting diodes according to the second to fifth embodiments, all the components including the organic light emitting diode positioned in the second electrode have a multilayer structure having a triple layer or more and the uppermost layer is made of a transparent conductive material. Since it has the same configuration as any one, it will be mainly described in the encapsulation film.

First, referring to FIG. 13, the organic light emitting diode 601 according to the sixth embodiment of the present invention has an encapsulation film having a multilayer structure on the second electrode 257 of the organic light emitting diode E. 272) is provided.

At this time, the encapsulation film 272 has a quadruple structure in which organic materials, more specifically, organic films 272a and 272c made of monomers or polymers and inorganic films 272b and 272d made of an inorganic insulating material are sequentially alternated. It is characterized by being stacked to form a.

 In general, the encapsulation film generally has a five-layer structure in which an organic film and an inorganic film are alternately formed.

However, in the case of the organic light emitting diode 601 according to the sixth embodiment of the present invention, since the uppermost layer 259c of the second electrode 257 is made of a transparent conductive material, the constitutional characteristics are reflected to the By using the lowest layer of the inorganic film (not shown) of the encapsulation film 272 as the uppermost layer 259c of the second electrode 257 made of a transparent conductive material, that is, the organic film and the inorganic film are alternately formed. It is characterized in that it is formed to have a four-layer structure of one organic film 272a / first inorganic film 272b / second organic film 272c / second inorganic film 272d.

In the case of the organic light emitting device 601 according to the sixth embodiment of the present invention, the encapsulation film 272 is formed of four layers, so that the encapsulation film made of the conventional five layers is limited. Layers can be omitted, which has the effect of simplifying the manufacturing process.

Meanwhile, referring to FIG. 14, in the case of the organic light emitting diode 701 according to the modified example of the sixth embodiment, the encapsulation film 772 is a transparent conductive material among the second electrodes 257 having a multilayer structure. The uppermost layer 259c of FIG. 5 is omitted, and the first inorganic layer 772a / the first organic layer 772b / the second inorganic layer (259b of FIG. 5) is formed on the low resistance material layer (259b of FIG. 5). 772c) / second organic film 772d / third inorganic film 772e.

In the case of the organic light emitting diode 701 according to the modified example of the sixth exemplary embodiment, the top layer (259c of FIG. 5) made of the transparent conductive material of the second electrode 257 is omitted and forms an encapsulation film having a 5-layer structure. The first inorganic film 772a, which is the lowest layer of 772, replaces this, and this also has the effect of simplifying the manufacturing process.

On the other hand, in the organic light emitting device 701 according to the modification of the sixth embodiment, the second electrode 257 of the organic light emitting diode E alternates between the transparent conductive material layer and the low resistance material layer and is more than three layers. Although there is room to reduce the effect of improving the transmittance generated by forming a multilayer structure, the organic light emitting device 701 according to the modification of the sixth embodiment of the present invention is in accordance with the fifth embodiment of the present invention. Organic light having different thicknesses for each of the first, second, and third pixel areas (P1, P2, and P3 of FIG. 11) emitting blue, green, and red light in the second electrode, which is presented through the organic light emitting diode (see FIG. 11). When the organic material layer 564 of FIG. 11 is formed, the thickness of the organic material layer 564 of FIG. 11 may be adjusted to prevent a factor of reducing transmittance improvement.

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

101 organic light emitting 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 area DTr: driving thin film transistor
P: pixel area

Claims (27)

A first substrate on which a display area having a plurality of pixel areas is defined;
A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor;
A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region;
An organic emission layer formed on the first electrode in the bank;
A second electrode formed on the organic light emitting layer and the bank, and formed on the entire display area, and having a double layer structure having a lower layer of a first thickness made of magnesium-silver alloy and an upper layer of a second thickness made of a transparent conductive oxide on the lower layer;
An organic light emitting device comprising a.
The method of claim 1,
The transparent conductive oxide is an organic light emitting device, characterized in that the indium zinc oxide (IZO) or indium tin oxide (ITO).
A first substrate on which a display area having a plurality of pixel areas is defined;
A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor;
A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region;
An organic emission layer formed on the first electrode in the bank;
A second electrode having a first thickness formed on an entire surface of the display area above the organic emission layer and the bank, and having a single layer structure of a magnesium-silver alloy;
A transparent insulating layer in contact with the second electrode and formed over the display area
An organic light emitting device comprising a.
The method of claim 3, wherein
The transparent insulating layer is made of silicon oxide (SiO ₂ ) or aluminum oxide (Al ₂ O ₃ ) as an inorganic insulating material, or an organic light emitting device, characterized in that made of a polymer or a monomer as an organic insulating material.
The method according to claim 1 or 3,
The switching and driving thin film transistor becomes a p-type thin film transistor, wherein the first electrode serves as an anode electrode, the second electrode serves as a cathode electrode.
The method of claim 5, wherein
The first electrode has a single layer structure made of indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive material having a high work function value, or the drain electrode of the driving thin film transistor. A first layer made of any one of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), which are in contact with each other and have excellent reflectivity, and a second layer made of the transparent conductive material and in contact with the organic light emitting layer. An organic electroluminescent device characterized by forming a double layer structure.
The method according to claim 1 or 3,
A gate line and a data line crossing the first substrate to define the pixel region, and a power line line parallel to the data line are formed on the first substrate, and the gate and data lines respectively include a gate electrode of the switching thin film transistor; An organic light emitting device, characterized in that connected to the source electrode.
A first substrate on which a display area having a plurality of pixel areas is defined;
A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor;
A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region;
An organic emission layer formed on the first electrode in the bank;
A low-resistance metal layer formed over the organic light-emitting layer and the bank and over the display area, the first layer having a first thickness of a first metal, a first transparent conductive layer made of a transparent conductive oxide, and a low resistance metal material And a second layer having a structure of the first layer and the first set layer formed by stacking one set layer formed of a triple layer of a second transparent conductive layer made of a transparent conductive oxide and an upper part of the first layer.
An organic light emitting device comprising a.
The method of claim 8,
And the second electrode has a sheet resistance of 1.9 kV / □ to 5 kV / □.
The method of claim 8,
The second electrode is formed of another set layer over the first set layer, the organic light emitting device, characterized in that made of the first layer, the first set layer and the second set layer.
11. The method of claim 10,
And the second electrode has a sheet resistance of 1 kV / □ to 2 kV / □.
The method according to claim 8 or 10,
The first layer is made of any one of silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg), copper (Cu), calcium (Ca),
The transparent conductive layer is made of indium tin oxide (ITO) or indium zinc oxide (IZO),
The low resistance metal layer is an organic light emitting device, characterized in that made of any one of silver (Ag), gold (Au), copper (Cu).
The method of claim 12,
The first layer has a thickness of 10 kPa to 50 kPa,
The first and second set layers each have a thickness of 400 kPa to 1000 kPa, and each of the low resistance metal layers provided in the first and second set layers has a thickness of 150 kPa to 300 kPa, respectively. .
A first substrate on which a display area having a plurality of pixel areas is defined;
A switching thin film transistor and a driving thin film transistor formed in each pixel area 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 and in contact with the drain electrode of the driving thin film transistor;
A bank overlapping an edge of the first electrode and formed at a boundary of the pixel region;
An organic light emitting layer formed on the first electrode in the bank and emitting red, green, and blue light for each pixel area;
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 formed on the entire display area over the organic light emitting layer and the bank; A second electrode having a six-layer structure of 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
And the fourth layer is formed by varying its thickness for each pixel region in which the organic light emitting layer for emitting red, green, and blue light is provided.
15. The method of claim 14,
The fourth layer has a thickness of 600 Å to 1200 ,, and the portion overlapping with the organic light emitting layer emitting blue has the thinnest thickness, and the portion overlapping with the organic light emitting layer emitting red has the thickest thickness. Phosphorus organic electroluminescent device.
15. The method of claim 14,
The first layer has a thickness of 10 kPa to 50 kPa,
The third layer and the fifth layer made of the low resistance metal material have a thickness of 150 kPa to 400 kPa, respectively.
15. The method of claim 14,
The first layer is made of any one of silver (Ag), magnesium-silver alloy (Mg: Ag), gold (Au), magnesium (Mg), copper (Cu), calcium (Ca),
The transparent conductive oxide is indium tin oxide (ITO) or indium zinc oxide (IZO), and the organic material is any one of photoacryl, benzocyclobutene or a material forming the organic light emitting layer.
The low resistance metal material is an organic light emitting device, characterized in that made of any one of silver (Ag), gold (Au), copper (Cu).
15. The method of claim 14,
And the second electrode has a sheet resistance of 1 kW / □ to 3 kW / □.
15. The method of claim 14,
When the fourth layer is made of the organic material, the fourth layer is formed to be spaced apart from the boundary of each pixel region, and the third layer and the fifth layer are formed to contact each other at the boundary of the pixel region. Characterized in organic light emitting device.
The method according to any one of claims 8, 10 and 14,
The switching and driving thin film transistor becomes a p-type thin film transistor, wherein the first electrode serves as an anode electrode, the second electrode serves as a cathode electrode.
21. The method of claim 20,
The first electrode has a single layer structure made of indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive material having a high work function value, or the drain electrode of the driving thin film transistor. A first layer made of any one of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), which are in contact with each other and have excellent reflectivity, and a second layer made of the transparent conductive material and in contact with the organic light emitting layer. An organic electroluminescent device characterized by forming a double layer structure.
The method according to any one of claims 8, 10 and 14,
A gate line and a data line crossing the first substrate to define the pixel region, and a power line line parallel to the data line are formed on the first substrate, and the gate and data lines respectively include a gate electrode of the switching thin film transistor; An organic light emitting device, characterized in that connected to the source electrode.
The method according to any one of claims 1, 3, 8, 10 and 14,
An organic light emitting device, characterized in that it is provided with a transparent second substrate facing the first substrate for encapsulation corresponding to the first substrate.
The method according to claim 8, 10 and 14,
And the second substrate is formed in contact with the second electrode and has a multilayer structure in which an inorganic film and an organic film are alternately formed.
The method of claim 24,
The second substrate is an organic electroluminescent device, characterized in that a four-layer structure of the organic film / inorganic film / organic film / inorganic film.
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, and an inorganic film, and the second electrode contacting the second substrate is omitted because the uppermost layer made of a transparent conductive oxide is omitted. The organic light emitting device according to claim 1, wherein the second electrode contacts the layer of the low resistance material of the second electrode.
The method of claim 25 or 26,
The inorganic film is made of any one of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), silicon nitride (SiNx),
The organic light emitting device, characterized in that the organic film is made of a monomer or a polymer.

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