KR101680704B1 - Organic electro luminescent device - Google Patents

Abstract

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 with maximized luminous efficiency.

The present invention has a reflective pattern having a first thickness and in contact with a drain electrode through a drain contact hole as a first metal material, on top of a protective layer including a drain contact hole exposing a drain electrode of the driving thin film transistor .

A first electrode, an organic light emitting layer in a multilayer structure, and an organic electroluminescent device in which a second electrode is sequentially disposed on a reflective pattern are provided.

At this time, an optical buffer layer having a drain contact hole is provided between the protective layer and the reflection pattern. The protective layer is made of silicon oxide (SiO ₂ ) and the optical buffer layer is made of silicon nitride (SiNx).

The reflection pattern is connected to the drain electrode through the protective contact and the drain contact hole of the optical buffer layer.

An organic field, a light emitting element, a luminance, a reflectance, a color recall ratio, a reflection pattern,

Description

[0001] The present invention relates to an organic electroluminescent device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly to an organic electroluminescent device with maximized luminous efficiency.

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

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

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

However, in the active matrix method, a thin film transistor (a thin film transistor) which is a switching element for turning on / off a pixel is provided for each pixel region, and the first electrode connected to the thin film transistor The first electrode is turned on / off, and the second electrode facing the first electrode becomes a common electrode.

In the active matrix system, the voltage applied to the pixel region is charged in the storage capacitor, and power is applied until the next frame signal is applied. Thus, do. Therefore, since the same luminance is exhibited even when a low current is applied, an active matrix type organic electroluminescent device is mainly used since it has advantages of low power consumption, high definition, and large size.

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

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

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

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

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

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

2 is a cross-sectional view of one pixel region including a driving thin film transistor of a conventional organic electroluminescent device.

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

The organic electroluminescent diode E includes a first electrode 47 and a second electrode 58 which are opposed to each other with the organic light emitting layer 55 of the multi-layer structure interposed therebetween. The first electrode 47 is formed in contact with the drain electrode of the driving thin film transistor DTr for each pixel region P and the second electrode 58 is formed over the organic light emitting layer 55 . And a second substrate for encapsulation spaced apart from the second electrode is formed by adhering by a seal pattern formed on the rim.

Although not shown in the drawing, a switching thin film transistor having the same structure as that of the driving thin film transistor and connected to the gate and the data wiring is formed in each pixel region. In each pixel region, a first storage capacitor composed of a first storage electrode, a gate insulating film, and a second storage electrode, and a second storage capacitor composed of the second storage electrode, an interlayer insulating film, and a third storage electrode have a parallel structure Respectively.

On the other hand, in the organic light emitting layer having the organic electroluminescence multi-layer structure having the above-described structure, an electron injection layer and an electron injection layer are sequentially formed between the second electrode and the organic light emitting material layer, A hole transporting layer and a hole injection layer are formed between the organic light emitting material layer and the first electrode.

The light emitted from the organic light emitting diode having such a structure will be described as follows. Light emitted from a specific wavelength band is emitted according to the characteristics of the organic light emitting material, which is a light source, from the organic light emitting material layer. . Since the refractive index is determined for each wavelength band of the medium when passing through various media constituting the various layers on the light propagation path, the reflectance and the transmittance are determined accordingly. This can be used to optimize the chromaticity and intensity of light.

A conventional organic electroluminescent device includes a first electrode made of a transparent conductive material having a relatively high work function value and a metal material having a relatively low work function value. An electron injection layer and an electron transport layer an electron transporting layer, an organic light emitting material layer, a hole transporting layer, and a hole injection layer are formed on the first electrode, a protective layer made of an inorganic insulating material, Lt; / RTI > Therefore, the properties of the final output light are determined by the thickness of the various material layers and the refractive index of the wavelength band.

The reflectance ratio is determined by the ratio of the refractive index between the material layers on the optical path, and the reflected light is reflected back to the second electrode to cause enhancement and destructive interference with the light emitted toward the original first substrate surface. In this case, the thickness of the material layer may be adjusted to red, green, and blue so that constructive interference occurs.

However, since the conventional organic electroluminescent device having the above-described structure has a low reflectance on the optical path, it is difficult to shield the low color purity component from the light, thereby raising the color reproducibility and limiting the light efficiency.

It is an object of the present invention to provide an organic electroluminescent device which emits light having a high luminance and a high color reproducibility by increasing the reflectivity of light emitted from the organic light emitting material layer.

According to an aspect of the present invention, there is provided an organic electroluminescent device comprising: a gate and a data line formed to intersect a pixel region and a boundary of the pixel region on a first substrate defined as a driving region and a switching region within the pixel region; A switching and driving thin film transistor formed in the switching and driving regions, respectively; And a drain contact hole exposing the drain electrode of the driving thin film transistor on the entire surface of the pixel region; A reflective pattern formed in the pixel region and having a first thickness, which is in contact with the drain electrode of the driving thin film transistor over the protective layer as the first metal material through the drain contact hole; A first electrode formed on the reflective pattern in the pixel region, the first electrode being formed of a transparent conductive material and serving as an anode electrode; A bank formed on a boundary of the pixel region and overlapping an edge of the first electrode; An organic light emitting layer formed on the first electrode corresponding to the bank surrounded region, the organic light emitting layer having a multilayer structure; A second electrode formed on the organic light emitting layer of the multi-layer structure and formed of a metal material having a relatively low work function value without distinguishing pixel regions, and serving as a cathode electrode; A second substrate facing the first substrate; And a seal pattern formed along the first and second substrate edges.

The first thickness of the reflection pattern is 10 nm to 20 nm.

The organic light emitting layer of the multi-layer structure sequentially emits red, green, and blue light corresponding to neighboring three pixel regions, and each of the organic light emitting layers of the multi-layer structure emitting red, A hole injection layer, a hole transporting layer, an organic light emitting material layer, and an electron transporting layer are sequentially stacked from the first electrode. Each of the hole injection layers formed in the pixel regions emitting red, green, and blue has a thickness of 45 nm to 55 nm, 25 nm to 35 nm, and 5 nm to 15 nm, and the red, Each of the hole transporting layers formed in the pixel region that emits light has the same thickness of 5 nm to 15 nm and each organic light emitting material layer formed in the pixel region emitting red, The electron transporting layer formed in the pixel region emitting red, green and blue light has a thickness of 15 nm to 25 nm with the same thickness . In addition, an electron injection layer is formed between the electron transport layer and the second electrode, and each electron injection layer formed in the pixel region emitting red, green, And has the same thickness of 10 nm to 50 nm.

The optical buffer layer having a drain contact hole is formed between the protective layer and the reflective pattern, the protective layer is the optical buffer layer of silicon oxide (SiO ₂₎ is preferably made of silicon nitride (SiNx).

Wherein the switching and driving thin film transistor comprises a semiconductor layer composed of a first region of pure polysilicon and a second region of impurity polysilicon on both sides thereof, a gate insulating film, a gate electrode formed corresponding to the first region, An interlayer insulating layer formed to have a semiconductor layer contact hole exposing the second region and source and drain electrodes spaced apart from each other in contact with the second region through the semiconductor layer contact hole, to be.

In addition, a storage region is defined in each pixel region, and a first storage electrode sequentially stacked in the storage region, a gate insulating film, a second storage electrode, an interlayer insulating film, and a third storage electrode are sequentially stacked to form a first And a second storage capacitor.

The organic electroluminescent device according to the present invention has an appropriate thickness in the organic light emitting layer to selectively transmit and reflect selectively to form a selective reflection layer, thereby enhancing the reflectance, thereby achieving high luminance and improving color reproducibility.

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

3 is a cross-sectional view of one pixel region including a driving thin film transistor of an organic electroluminescent device according to an embodiment of the present invention. For convenience of description, a region where the driving thin film transistor DTr is formed is defined as a driving region DA, and a region where a switching thin film transistor is formed, not shown in the drawing, is defined as a switching region.

The organic electroluminescent device 101 according to the present invention includes a first substrate on which a driving and switching thin film transistor DTr (not shown), storage capacitors StgC1 and StgC2 and an organic electroluminescent diode E are formed 110 and a second substrate 170 for encapsulation.

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

The first region 110 is formed of pure polysilicon corresponding to the driving region DA and the switching region (not shown). The central region of the first region 110 includes a first region 113a and a second region 113b. And a second region 113b doped with impurities at a high concentration on both sides of the semiconductor layer 113a.

The storage region StgA is formed with a first storage electrode 115 connected to the semiconductor layer 113 of the driving region DA and made of polysilicon doped with impurities.

Next, the semiconductor layer 113 of the switching and driving region (not shown) and the first storage electrode 115 of the storage region StgA are covered with a gate insulating layer 116 as an inorganic insulating material. Respectively. A gate electrode 121 is formed in the switching and driving region (not shown) on the gate insulating film in correspondence to the first region 113a made of only pure polysilicon of the semiconductor layer 113, A second storage electrode 118 is formed in the storage region StgA to correspond to the first storage electrode 115. At this time, the first storage electrode 115, the first gate insulating film 116, and the second storage electrode 118 form a first storage capacitor StgC1.

On the other hand, an interlayer insulating film 123 is formed on the gate electrode 121 and the second storage electrode 118 as an inorganic insulating material. At this time, in the switching and driving regions (not shown), the interlayer insulating layer 123 and the gate insulating layer below the interlayer insulating layer 123 are removed 116 corresponding to the impurity-doped second region 113b, And a semiconductor layer contact hole 125 exposing the second region 113b on both sides of the semiconductor layer 121 are provided.

In addition, in the switching and driving region (not shown), the second contact region 113b contacts the second region 113b of the impurity-doped polysilicon via the semiconductor contact hole 125 above the interlayer insulating layer 123, And source and drain electrodes 133 and 136 spaced apart by the gate electrode 121 are formed, respectively. A semiconductor layer 113 including the source and drain electrodes 133 and 136 and a second region 113b contacting the electrodes 133 and 136 and a gate electrode The insulating film 116 and the gate electrode 121 constitute a driving thin film transistor DTr and a switching thin film transistor (not shown), respectively.

Although not shown in the drawing, the interlayer insulating layer 123 is connected to a source electrode (not shown) of the switching thin film transistor (not shown) and crosses the gate line (not shown) And a power line (not shown) is formed in parallel with the data line 130. The power line (not shown)

In the storage region StgA, a third storage electrode 138 overlapped with the second storage electrode 118 and connected to the power supply line (not shown) is formed on the interlayer dielectric 123, The second and third storage electrodes 118 and 138 overlapping each other and the interlayer insulating film 123 positioned between the two electrodes 118 and 138 constitute a second storage capacitor StgC2.

On the other hand, a protective layer 140 is formed on the driving and switching thin film transistor (DTr) (not shown) as silicon oxide (SiO ₂ ), which is an inorganic insulating material. An optical buffer layer 141 for increasing luminous efficiency is formed of silicon nitride (SiNx), which is an inorganic insulating material. A drain contact hole 143 exposing the drain electrode 136 of the driving TFT DTr is formed in the optical buffer layer 141 and the passivation layer 140 under the optical buffer layer 141.

The organic thin film transistor TFT1 is formed on the optical buffer layer 141 having the drain contact hole 143. The organic thin film transistor TFT1 is formed over the drain electrode 136 of the driving thin film transistor DTr through the drain contact hole 143, And a reflection pattern 145 having a thickness of 5 nm to 20 nm and having a very thin thickness is formed so as to allow selective transmission through the pixel region P in order to increase the reflection efficiency.

A first electrode 147 is formed on the reflection pattern 145. The first electrode 147 serves as an anode electrode. The first electrode 147 has a relatively large work function and is made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide It is characterized by losing.

Next, a bank 150 is formed on the boundary of each pixel region P above the first electrode 147. At this time, the bank 150 is formed so as to surround the pixel region P and overlap the rim of the first electrode 147 and expose the central portion of the first electrode 147.

A hole injection layer 160e and a hole transporting layer 160d are formed on the first electrode 147 in the region surrounded by the bank 150 of each pixel region P, An organic light emitting layer 160 composed of an organic light emitting material layer 160a, an electron transporting layer 160b and an electron injection layer 160c. At this time, the electron injection layer 160c may be omitted.

Here, although not shown in the drawing, the organic light emitting material layer 160 is different in red, green, and blue pixel regions P from each other. A thickness of about 55 nm to about 65 nm for the red organic light emitting material layer emitting red light, a thickness of about 40 nm to about 50 nm for the green organic light emitting material layer, and a thickness of about 35 nm to about 45 nm for the blue organic light emitting material layer .

It is preferable that the hole injection layer 160e is formed to have a thickness of 45 nm to 55 nm, 25 nm to 35 nm, and 5 nm to 15 nm, respectively, for the red, green, and blue organic light emitting material layers, It is preferable that the hole transporting layer 160d is formed to have a thickness of about 5 nm to 15 nm for the red, green and blue organic light emitting material layers.

Also, the electron transporting layer 160b is preferably formed to have a thickness of 15 nm to 25 nm for the red, green, and blue organic light emitting material layers, and the electron injection layer 160c are preferably formed to have a thickness of 10 nm to 50 nm for the red, green and blue organic light emitting material layers.

On the organic light emitting layer 160 and the bank 150, a second electrode 163 serving as a cathode is formed on the entire display region and has a plate shape and a relatively small work function value. Is formed. At this time, the first and second electrodes 147 and 163 and the organic light emitting layer 160 formed therebetween form an organic light emitting diode E.

The second substrate 170, which is transparent and opposed to the first substrate 110 having such a structure, is bonded together by a seal pattern (not shown) along the rim thereof to form the upper emission type organic electroluminescent device 101 ). At this time, the first substrate 110 and the second substrate 170 are filled with nitrogen (N ₂ ), which is an inert gas, or are formed to have a vacuum atmosphere.

In the case of the organic electroluminescent device 101 according to the present invention having the above-described structure, an optical buffer layer 141 made of silicon nitride (SiNx) is provided to increase the luminous efficiency of the organic light emitting layer 160, By providing the reflection pattern 145 as a metallic material having a high luminous efficiency under the electrode 147, the low color purity component is blocked and the reflectance is improved. The light reflected by the reflection pattern 145 or the light reflected by the second electrode 163 after being reflected by the reflection pattern 145 and the light reflected from the organic light emitting material layer 160a The thickness of the reflective pattern 145 and the thickness of the red, green, and blue organic light emitting material layers 160a and the hole injection layer 160a may be set so as to cause constructive interference with light emitted toward the first substrate 110. [ the thickness of each of the electron injection layer 160e, the hole transporting layer 160d, the electron transporting layer 160b and the electron injection layer 160c is appropriately adjusted, And the color purity of each red, green, and blue light is improved.

This phenomenon may occur because some of the material layers formed between the reflective pattern 145 and the second electrode 163 have different refractive indexes or are partially reflected or refracted under the total reflection condition And when the angle of incidence is larger than the critical angle, the light is totally reflected at the boundary surface when proceeding to a small medium.) In the case of the light incident at a specific angle, total reflection is performed in each material layer. In particular, when the reflective pattern 145 is made of aluminum (Al), the refractive index is about 0.64 and the first electrode 147 of the transparent conductive material formed in contact therewith is nitrided And the refractive indexes of the optical buffer layer 141 of silicon (SiNx) are 2.02 and 1.94, respectively. Therefore, when the light passing through the first electrode 147 in contact with the reflective pattern 145 and incident on the reflective pattern 145 is greater than the critical angle, the total reflection condition is satisfied and the second electrode 163 is formed And between the reflection pattern 145 and the second electrode 163 until it is incident with an angle smaller than the critical angle. Accordingly, light having a low purity color component is removed from the front surface viewed by the user, and the brightness is improved by recycling light.

FIGS. 4A, 4B, and 4C are graphs showing the intensities of light of red, green, and blue wavelengths corresponding to red, green, and blue pixel regions of an organic electroluminescent device according to the related art and the present invention, respectively.

Referring to FIG. 4A, it can be seen that the intensity of the light emitting red light having a peak wavelength of 625 nm is about 2.0 in the conventional case, but about 6.5 in the case of the present invention. Which means that the purity is increased in the indication. In addition, it can be seen that the width of the graph is formed smaller than that of the conventional one based on the wavelength of 625 nm, which means that only light of a wavelength near the pure red color is emitted and light of low color purity is removed.

Also, referring to FIGS. 4B and 4C, the light emitted from the green and blue pixel regions is red, and the peak of the graph is higher than that of the prior art, and the width of the graph is also narrower. This means that the color purity is also increased for green and blue, respectively, and light having low purity for each color is removed.

On the other hand, the increase in the intensity of the wavelength band indicating red, green, and blue means that the intensity of light is increased, which indicates that the brightness is finally improved.

The red light emitted through the red pixel region was 9.2 cd / A in the conventional case, but 19.7 cd / A in the organic light emitting device according to the present invention, and 19.4 cd / A in green and blue in the conventional case, It was found from simulation that the increase from 3.8cd / A was increased to 36.8cd / A and 3.9cd / A. In other words, it can be seen that the luminance of blue is similar to that of the prior art, but the luminance of red and green is improved almost twice.

Although it is not shown in the figure, the red, green, and blue light emitted from the organic light emitting device according to the present invention having the above-described brightness and color purity are displayed in a color coordinate system (CIE1931) When the area of the light emitted from the light emitting device in the color coordinate system is 100, the area of the light emitted from the organic light emitting device according to the present invention is 120.7, which indicates that the color reproduction ratio is improved by about 20% I could.

Hereinafter, a method of manufacturing an organic electroluminescent device according to an embodiment of the present invention will be described in brief with reference to FIG.

First, amorphous silicon is deposited on a transparent first insulating substrate 110 to form an amorphous silicon layer (not shown), and the amorphous silicon layer is exposed to a laser beam or heat treatment to form a polysilicon layer Lt; / RTI >

Thereafter, a polysilicon layer (not shown) is patterned by performing a mask process including a photoresist application, exposure using an exposure mask, development of an exposed photoresist, etching, and strip, thereby forming a switching and driving region , DA), and a storage pattern (not shown) having a pure polysilicon state is formed in the storage region StgA.

Next, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) is deposited on the semiconductor pattern (not shown) of the pure polysilicon and the storage pattern (not shown) to form the gate insulating film 116, Is formed on the front surface.

Next, the gate insulating film 116 is exposed on the gate insulating film 116 in correspondence to the storage region StgA, a photoresist pattern (not shown) is formed on the other regions, and then impurities are doped, The storage pattern (not shown) formed on the first storage electrode StgA forms the first storage electrode 115 in the impurity polysilicon state.

Next, a photoresist pattern (not shown) is removed by advancing a strip, and then a low resistance metal material such as aluminum (Al), aluminum alloy (AlNd), copper (Cu) (Not shown) formed in the switching and driving regions (not shown) by patterning the first metal layer (not shown) by depositing one of the first and second metal layers The gate electrode 121 is formed. At the same time, a gate wiring (not shown) connected to the gate electrode formed in the switching region (not shown) and extending in one direction is formed on the second gate insulating film 119, The second storage electrode 118 is formed in correspondence with the first storage electrode 115. At this time, the first storage electrode 115, the gate insulating film 116, and the second storage electrode 118, which are sequentially stacked on the substrate 110, form a first storage capacitor StgC1.

Next, by doping an impurity, that is, a trivalent element or a pentavalent element, into each semiconductor pattern (not shown) formed in the switching and driving regions (not shown) using the gate electrode 120 as a blocking mask, The portion of the gate electrode 121 located outside the electrode 121 constitutes the second region 113b doped with the impurity and the portion corresponding to the gate electrode 121 of which the doping is prevented is a semiconductor region of the first region 113a of pure polysilicon. Layer 113 is formed.

Next, the first and second regions (113a, 113b) in the semiconductor layer 113 to the top of a silicon oxide inorganic insulating material on the front (SiO ₂₎ or silicon oxide (SiO ₂₎ an interlayer insulating film 123 to deposit the divided . Thereafter, the masking process is performed to pattern the interlayer insulating film 123 and the second and first gate insulating films 119 and 116 below the second interlayer insulating film 123 to form a second semiconductor layer (not shown) formed in the switching and driving regions The semiconductor layer contact hole 125 exposing the region 113b is formed.

Next, a metal material such as aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, chrome (Cr), or molybdenum (Mo) is deposited on the interlayer insulating layer 123, (Not shown), which are patterned by a masking process, are contacted with the second region 113b through the semiconductor layer contact holes 125, respectively, in the switching and driving regions (not shown) Source and drain electrodes 133 and 136 are formed. At this time, the semiconductor layer 113, the first and second gate insulating films 116, the gate electrodes 121, and the interlayer insulating film 123, which are sequentially stacked in the switching and driving regions (not shown) The source and drain electrodes 133 and 136 constitute switching and driving thin film transistors (not shown). A data line 130 connected to a source electrode (not shown) formed in the switching region (not shown) on the interlayer insulating layer 123 and intersecting the gate line (not shown) to define a pixel region P (Not shown) spaced apart from the data line 130 and arranged side by side.

In addition, a third storage electrode 138 is formed on the interlayer insulating film 123 in the storage region StgA. At this time, the second storage electrode 118, the second gate insulating film 119, the interlayer insulating film 123, and the third storage electrode 138 form a second storage capacitor StgC2.

Next, silicon oxide (SiO ₂ ), which is an inorganic insulating material, is deposited on the source and drain electrodes 133 and 136 and the third storage electrode 138 to form a protective layer 140, The optical buffer layer 141 is formed by depositing silicon nitride (SiNx), which is an insulating material. Then, the optical buffer layer 141 and the lower protective layer are patterned by performing a mask process to form a drain contact hole 143 exposing the drain electrode 136 of the driving thin film transistor DTr.

Next, a metal material such as aluminum (Al) or aluminum alloy (AlNd) having excellent reflection efficiency is deposited on the optical buffer layer 141 having the drain contact hole 143 so as to have a thickness of about 10 nm to 20 nm, (ITO) or indium-zinc-oxide (IZO), which is a transparent conductive material having a relatively high work function value, is deposited thereon, and then these two material layers are patterned collectively or continuously to form pixel regions P having a thickness of about 10 nm to 20 nm and in contact with the drain electrode 136 of the driving thin film transistor DTr through the drain contact hole 143 for each of the first electrodes 147 are formed.

Thereafter, a first organic insulating material layer (not shown) is formed on the first electrode 147 by applying an organic insulating material such as photo acryl or benzocyclobutene (BCB) The bank 150 is formed in such a manner as to border the edge of the first electrode 147 including the boundary of the pixel region P. [

Next, a hole injection layer 160e, a hole transporting layer 160c, and a hole transporting layer 160c are sequentially formed on the first electrode 147 exposed between the banks 150 with respect to the substrate 110 on which the bank 150 is formed. an organic light emitting layer 160 composed of a light emitting layer 160d, an organic light emitting material layer 160a, an electron transporting layer 160b and an electron injection layer 160c is formed. Here, the layers constituting the organic light emitting layer 160 may be formed by thermal evaporation using a shadow mask, or by ink jetting, nozzle coating, or the like.

Next, a metal material having a relatively low work function value such as aluminum (Al), an aluminum alloy, silver (Ag), magnesium (Mg), or gold (Au) is displayed on the organic light emitting layer 160 having the multi- The second electrode 163 is formed on the entire surface of the first substrate 110 to complete the first substrate 110. Here, the first electrode 147, the organic light emitting layer 160, and the second electrode 163 form an organic light emitting diode (E).

On the other hand, a seal pattern (not shown) is formed along the edge of the display region with respect to the completed first substrate 110 as described above, the second substrate 170 made of a transparent material is opposed, It is possible to complete the organic EL device 101 according to the embodiment of the present invention by, for example, bonding the first and second substrates 110 and 170 together in a nitrogen (N ₂ ) gas atmosphere or a vacuum atmosphere.

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

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

3 is a cross-sectional view of one pixel region including a driving thin film transistor, a storage capacitor, and an organic light emitting diode of an organic electroluminescent device according to an embodiment of the present invention.

FIGS. 4A, 4B, and 4C are graphs showing the intensities of light in the red, green, and blue wavelength ranges corresponding to the red, green, and blue pixel regions of the organic electroluminescent device according to the related art and the present invention, respectively.

Description of the Related Art

110: first substrate 113: semiconductor layer

113a and 113b: first and second regions 115: first storage electrode

116: gate insulating film 118: second storage electrode

121: gate electrode 123: interlayer insulating film

125: semiconductor layer contact hole 130: data line

133: source electrode 136: drain electrode

138: third storage electrode 140: protective layer

141: Optical buffer layer 143: Drain contact hole

145: reflection pattern 147: first electrode

150: bank 160: organic light emitting layer

160a: organic light emitting material layer 160b: electron transporting layer

160c: electron injection layer 160d: hole transport layer

160e: Hole injection layer 163: Second electrode

DA: driving region DTr: driving thin film transistor

E: organic electroluminescent diode P: pixel region

StgA: storage area StgC1: first storage capacitor

StgC2: Second storage electrode

Claims (9)

A first substrate having a pixel region and a driving region and a switching region defined in the pixel region; A switching and driving thin film transistor provided in each of the switching and driving regions; A protective layer having a drain contact hole exposing the drain electrode of the driving thin film transistor over the entire surface of the pixel region; A reflective pattern having a first thickness in contact with the drain electrode of the driving thin film transistor over the protective layer as a first metal material in the pixel region; A first electrode serving as an anode electrode on the reflective pattern in the pixel region;  A bank overlapped with an edge of the first electrode and provided at a boundary of the pixel region; An organic light emitting layer provided on the first electrode corresponding to a region surrounded by the bank, the organic light emitting layer having a multilayer structure; A second electrode serving as a cathode electrode over the organic light emitting layer of the multilayer structure; A second substrate facing the first substrate; And a seal pattern disposed along the first and second substrate edges, The reflection pattern and the first electrode are patterned in the same process so that their ends match, Between the protective layer and the reflective pattern is provided with an optical buffer layer having a drain contact hole, the protective layer is the optical buffer layer of silicon oxide (SiO ₂₎ is formed of a silicon nitride (SiNx), Wherein the reflective pattern is connected to the drain electrode through the protective contact hole and the drain contact hole of the optical buffer layer. The method according to claim 1, Wherein the first thickness of the reflection pattern is 10 nm to 20 nm. The method according to claim 1, Wherein the organic light emitting layer of the multi-layer structure sequentially emits red, green, and blue light corresponding to neighboring three pixel regions, respectively. The method of claim 3, Each of the organic light emitting layers having a multilayer structure emitting red, green, and blue light has a hole injection layer, a hole transporting layer, an organic light emitting material layer, and an electron transporting layer sequentially from the first electrode. And an electron transporting layer are stacked. 5. The method of claim 4, Each of the hole injection layers provided in the pixel regions emitting red, green and blue light has a thickness of 45 nm to 55 nm, 25 nm to 35 nm, and 5 nm to 15 nm,  Each of the hole transporting layers provided in the pixel region emitting red, green, and blue has the same thickness of 5 nm to 15 nm, Each organic light emitting material layer provided in the pixel region emitting red, green, and blue light has a thickness of 55 nm to 65 nm, 40 nm to 50 nm, and 35 nm to 45 nm, Wherein each of the electron transporting layers provided in the pixel region emitting red, green and blue light has an identical thickness of 15 nm to 25 nm. 6. The method of claim 5, An electron injection layer is provided between the electron transport layer and the second electrode, Each of the electron injection layers provided in the pixel regions emitting red, green and blue has the same thickness of 10 nm to 50 nm. delete The method according to claim 1, The switching and driving thin film transistor includes a first region of pure polysilicon and a second region of impurity polysilicon on both sides of the first region, a gate insulating film, and a gate electrode provided corresponding to the first region, An interlayer insulating layer having a semiconductor layer contact hole exposing the second region, and source and drain electrodes spaced apart from each other in contact with the second region through the semiconductor layer contact hole. 9. The method of claim 8, Wherein the first storage electrode, the second storage electrode, the interlayer insulating film, and the third storage electrode are sequentially stacked on the first storage electrode and the second storage electrode, 2 An organic electroluminescent device constituting a storage capacitor.

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