KR100754127B1 - Organic electroluminescent display and manufacturing method - Google Patents

Abstract

The present invention relates to a full color organic light emitting display device and a method for manufacturing the auxiliary hole transport layer between the red and green light emitting layers and the hole transport layer.

A full color organic light emitting display device according to an embodiment of the present invention includes a conductive substrate having red, green, and blue pixel regions, first electrode layers formed on the pixel regions, and formed on the first electrode layer. An auxiliary hole transport layer patterned in the red pixel area and the green pixel area at a position corresponding to the electrode layer, and a red light emitting layer by patterning a red light emitting material at a position corresponding to the red pixel area on the auxiliary hole transport layer; A green light emitting layer formed by patterning a green light emitting material at a position corresponding to the green pixel region, a blue light emitting layer formed of a blue light emitting material on the entire surface of the substrate on which the red light emitting layer and the green light emitting layer are formed, and formed on the blue light emitting layer And a second electrode layer to be formed.

 Accordingly, lifespan and color purity of the full color organic light emitting display device can be improved.

Auxiliary hole transport layer, light emitting layer, microcavity, color purity

Description

Organic electroluminescent display and manufacturing method thereof {FULL COLOR ORGANIC LIGHT EMITTING DISPLAY AND METHOD FOR FABRICATING THE SAME}

1 is a schematic layout showing one pixel area according to the prior art;

FIG. 2 is a schematic cross-sectional view taken along line II ′ of FIG. 1.

3 is a schematic layout showing one pixel area according to the present invention;

4 is a schematic cross-sectional view taken along line II-II ′ of FIG. 3.

♣ Explanation of symbols for the main parts of the drawing ♣

  210: substrate 221, 223, 225: first electrode layer

  230: hole injection layer 240: hole transport layer

  251,253: Secondary hole transport layer 261,263,270: Red, green, blue light emitting layer

  280: electron transport layer 290: second electrode layer

The present invention relates to a full color organic light emitting display device and a method of manufacturing the same. More specifically, an auxiliary hole transport layer is formed between a red and green light emitting layer and a hole transport layer to amplify the color light luminance of the red and green wavelength bands and to improve color purity. The present invention relates to a full color organic light emitting display device and a method of manufacturing the same.

Recently, a flat panel display (FPD: Flat Panel Display) having the advantages of small size and light weight by solving problems of weight and size of a cathode ray tube (CRT) has been attracting attention. Such flat panel displays include liquid crystal displays (LCDs), light emitting diodes (LEDs), field emitter displays (FEDs), and plasma display panels (PDPs). There is this.

Among the flat panel display devices, the light emitting display device has a wider operating temperature range than other flat panel display devices, is resistant to shock and vibration, has a wide viewing angle, and provides a fast response speed, thereby providing clean moving images. In the future, it is attracting attention as the next generation flat panel display.

Such light emitting display devices include an organic light emitting display device using an organic light emitting diode and an inorganic light emitting display device using an inorganic light emitting diode. The organic light emitting diode includes an anode electrode, a cathode electrode, and an organic light emitting layer disposed between them and emitting light by a combination of electrons and holes. The inorganic light emitting diode, unlike the organic light emitting diode, includes an emission layer made of an inorganic material, for example, a light emitting layer made of a PN bonded semiconductor.

Among them, the organic light emitting display device deposits a material emitting red (R), green (G), and blue (B) in a subpixel area formed in at least one pixel area on a substrate, thereby forming a thin film transistor formed on the substrate. Each subpixel region emits light by driving. Positioning each of the red (R), green (G), and blue (B) subpixel regions at different positions is integrated by the human eye so that light from the three primary colors can recognize various colors with only their primary colors. In this case, a full color display is realized.

Hereinafter, an organic light emitting display device according to the related art will be described in detail with reference to the accompanying drawings.

1 is a schematic layout showing one pixel area according to the prior art.

Referring to FIG. 1, the pixel area 10 according to the related art is composed of red (R), green (G), and blue (B) pixel areas, and the area of each pixel area is the same in a stripe shape. Is formed. Each pixel region is divided by the pixel defining layer 11 formed between the respective pixels.

FIG. 2 is a schematic cross-sectional view taken along line II ′ of FIG. 1.

Referring to FIG. 2, the full-color organic light emitting display according to the related art is formed by patterning first electrode layers 121, 123, and 125 formed on each substrate on the substrate 110, and forming a hole injection layer 130 and a hole. The transport layer 140 is formed on the front side. The light emitting layers 151, 153, and 155 of red (R), green (G), and blue (B) are formed to correspond to the first electrode of each pixel, and the hole suppression layer 160 and the electron transport layer 170 are formed on the entire surface. The second electrode layer 180 is formed on the electron transport layer 170.

The light emitting layers 151, 153, and 155 of the red (R), green (G), and blue (B) pixels have a thickness suitable for each of the red (R), green (G), and blue (B) colors. G) and blue (B) pixels are formed on the first electrode layers 121, 123, and 125, and the hole injection layer 130, the hole transport layer 140, the hole suppression layer 160, and the electron transport layer 170, which are the charge transport layers, It is formed on the front surface of the substrate as a common layer.

As described above, in the prior art, when forming red (R), green (G), and blue (B) pixel regions, at least three patterning processes by deposition or transfer are required, and red (R), green (G), Since a fine pattern of the blue (B) pixel region must be formed, a misalignment may occur. In addition, since the phosphorescent material is used as a dopant for the fluorescent light emitting material, that is, the fluorescent light emitting material as the light emitting host. The hole suppression layer, which is faster than the movement of H and prevents the movement of holes on the light emitting layer, was essential. Accordingly, in the case of the phosphorescent light emitting device, since the hole suppression layer is required, there is a problem in that one process is further increased.

In addition, in recent years, the organic light emitting display device is flexible in view of driving characteristics, and thus, many studies have been conducted.

However, since the surface of the conductive substrate, which is a flexible substrate, is tens of microseconds or less, and has a very high reflectivity to visible light, the light generated from the light emitting layer of the organic light emitting display device is reflected on the surface of the substrate so that There is a problem of lowering the color purity.

Accordingly, the present invention has been devised to solve the above-mentioned conventional problems, and an object of the present invention is to provide a color hole luminance of red and green wavelength bands by forming an auxiliary hole transport layer between a red and green light emitting layer and a hole transport layer on a conductive substrate. The present invention provides a full color organic light emitting display device and a method of manufacturing the same, which can amplify and improve color purity.

In order to achieve the above object, the full color organic light emitting display device of the present invention comprises a conductive substrate having red, green and blue pixel regions, first electrode layers formed on each of the pixel regions, and the first electrode layer. An auxiliary hole transport layer formed on the red pixel area and the green pixel area at a position corresponding to the first electrode layer, and a red light emitting material at a position corresponding to the red pixel area on the auxiliary hole transport layer; A green light emitting layer is formed by patterning a red light emitting layer, and a green light emitting layer is formed by patterning a green light emitting material at a position corresponding to the green pixel region. And a second electrode layer formed on the blue light emitting layer.

Preferably, the auxiliary hole transport layer has an energy level of the hole transport layer, and the energy level is 2.41ev to 5.45ev. The semiconductor device may further include a hole injection layer and a hole transport layer on the substrate on which the first electrode layer is formed, and further include an electron transport layer between the blue light emitting layer and the second electrode layer. The conductive substrate is a metal thin film, and the metal thin film uses stainless steel or titanium.

Hereinafter, a full color organic light emitting display device and a manufacturing method thereof according to the present invention will be described in detail.

3 is a schematic layout showing one pixel area according to the present invention.

Referring to FIG. 3, one pixel area 20 is composed of red (R), green (G), and blue (B) pixel areas, and the area of each pixel area is formed to have a different size. . The red (R) and green (G) pixel areas are formed so as not to overlap each other, and the blue (B) pixel area having a relatively low luminous efficiency is the entire pixel area 20, that is, the red (R) and green (G) pixels. It is formed in common in the whole area.

The area of the blue (B) pixel except for the area where the red (R) pixel and the green (G) pixel are formed is larger than the area of the red (R) light emitting layer and the area of the green (G) light emitting layer.

Accordingly, by forming a blue (B) pixel area in common on the entire pixel area, the luminous efficiency of blue (B) with low luminous efficiency is improved to a level similar to that of red (R) and green (G), The lifespan of the full color organic light emitting display device according to the present invention can be improved.

In addition, an auxiliary hole transport layer (not shown) is formed in the red (R) pixel and the green (G) pixel to improve color light efficiency and color purity of the red (R) pixel and the green (G) pixel.

4 is a schematic cross-sectional view taken along line II-II ′ of FIG. 3.

Referring to FIG. 4, the full color organic light emitting display device 200 according to the present invention includes a conductive substrate 210 having red, green, and blue pixel regions, and first electrode layers 221, 223, and 225 formed on the pixel regions, respectively. ), The hole injection layer 230 formed on the first electrode layers 221, 223, and 225, the hole transport layer 240 formed on the hole injection layer 230, and the hole transport layer 240. And auxiliary hole transport layers 251 and 253 formed by patterning a hole transport material on the red pixel area and the green pixel area, and formed on the auxiliary hole transport layers 251 and 253 and a red light emitting material on the red pixel area. The patterned red light emitting layer 261 and the green light emitting layer 263 formed by patterning a green light emitting material on the green pixel region and the hole transport layer 240 are stacked over the red light emitting layer 261. And the green foot The blue light emitting layer 270 formed on the entire surface of the hole transport layer 240 having the layer 263 formed of a blue light emitting material, the electron transport layer 280 formed on the blue light emitting layer 270, and the electron transport layer ( 280 includes a second electrode layer 290 formed thereon.

The conductive substrate 210 has unit pixel regions of red (R), green (G), and blue (B). The substrate 210 may be formed by using stainless steel (SUS) or titanium (Ti), and may be formed in a flexible foil form to form the substrate 210 according to a shape desired by a user. Can be. In general, a thin film transistor is formed on the substrate 210. For convenience of description, a detailed description of the thin film transistor and a detailed description thereof will be omitted.

The first electrode layers 221, 223, and 225 are patterned and formed on the substrate 210 having unit pixel regions of red (R), green (G), and blue (B), respectively. In addition, according to the present invention, at least one layer of the first electrode layers 221, 223, and 225 is formed of a metal film as a reflective film as a top emission structure. Then, a pixel defining layer (not shown) defining the pixel region is formed.

Thereafter, the hole injection layer 230 and the hole transport layer 240 are formed on the entire surface of the substrate 210 on which the first electrode layers 221, 223, and 225 are formed. The hole injection layer 230 is typically any one selected from the group consisting of a low molecule such as CuPc, TNATA, TCTA, TDAPB and a polymer such as PANI, PEDOT. In addition, the hole transport layer 240 is typically an arylamine-based low molecule, hydrazone-based low molecule, stilbene-based low molecule, starburst-based low molecule, such as NPB, TPD, s-TAD, MTADATTA and carbazole-based polymer, arylamine-based polymer As the perylene-based and pyrrole-based polymers, any one selected from the group consisting of polymers such as PVK is used. The hole transport material as described above not only transports holes easily but also increases the probability of exciton formation. In addition, any one of the hole injection layer 230 and the hole transport layer 240 may be omitted.

Subsequently, the red light emitting layer 261 and the green light emitting layer 263 are patterned and formed on the hole transport layer 240 corresponding to the first electrode layers 221 and 223 formed in the red pixel area and the green pixel area.

Meanwhile, auxiliary hole transport layers 251 and 253 are formed between the red light emitting layer 261, the hole transport layer 240, and the green light emitting layer 263 and the hole transport layer 240, respectively. The auxiliary hole transport layers 251 and 253 are formed of a material having an energy level of the hole transport layer 240 to a thickness of about 100 kW to 1000 kW.

In general, in the conductive substrate of the organic light emitting display device, the surface of the substrate formed of the metal thin film is roughened. Accordingly, in order to use the metal thin film as a substrate of an organic light emitting display device, the surface of the metal substrate must be flattened by a chemical mechanical polishing (CMP) method. Through this process, the surface of the metal substrate is flattened to several tens of microwatts or less.

When the substrate formed using the above-described process method is applied to the top-emitting organic electroluminescent display, the light generated from the light emitting layer of the organic electroluminescent display is reflected on the surface of the substrate, partially transmitted and some light is reflected again. To the second electrode layer 290. However, such a conductive substrate has a very high reflection characteristic with respect to light in the visible region compared to the conventional glass substrate, thereby significantly reducing the color purity of the light emitting layer. This is because the surface of the substrate is tens of micrometers or less and smooth like a mirror so that the reflectivity to light is very high.

The auxiliary hole transport layers 251 and 253 are used to derive light in a desired wavelength band using a microcavity effect in order to solve the above-mentioned problems. The auxiliary hole transport layers 251 and 253 reinforce or The color purity of the red and green light emitting layers 261 and 263 is adjusted by dissipation.

The microcavity effect means that the light is repeatedly transmitted and reflected between the substrate 210 and the second electrode layer 290 to cause interference, and optical resonance between the substrate 210 and the second electrode layer 290 is generated. It is to control the color purity of the red and green light emitting layer (261, 263) by forming the auxiliary hole transport layer (251, 253) to occur.

For example, when the visible light of the red and green light emitting layers 261 and 263 emits light, the wavelengths of the light reflected by the auxiliary hole transport layers 251 and 253 from the second electrode layer 290 pass through the auxiliary hole transport layers 251 and 253. The wavelengths reflected by the substrate 210 indicate that constructive and destructive interference occurs between the interfaces between the red and green light emitting layers 261 and 263 and the auxiliary hole transport layers 251 and 253. When such constructive interference occurs, the interference intensity of light becomes a peak, and when the interference occurs, the interference intensity of light becomes zero.

Accordingly, in the present invention, the auxiliary hole transport layers 251 and 253 are formed to optimize the interference intensity of the light, thereby increasing the efficiency of the full color organic light emitting display device and reducing the change in the emission color, thereby reducing the red and green light emitting layers 261 and 263. Optimize color light brightness and color purity. Furthermore, furthermore, a display that provides an image of good quality can be provided.

The blue light emitting layer 270 has a relatively lower lifespan and emission efficiency than the red light emitting layer 261 and the green light emitting layer 263, and the red light emitting layer 261 and the green light emitting layer 263 are considered in consideration of the blue color. ) Is formed to approximately 100 kPa to 2000 kPa on the entire surface of the hole transport layer 240 is formed. In the present invention, the material used for each light emitting layer is not limited, but after the red light emitting layer 261 and the green light emitting layer 263 are formed, respectively, the blue light emitting layer 270 is formed as a common layer. When a phosphorescent light emitting material is used as the light emitting layer, the lifetime and the diffusion distance of the exciton are longer than that of the fluorescent light emitting layer using the fluorescent light emitting material as the light emitting layer. Accordingly, in the case of the light emitting layer using the phosphorescent light emitting material as a light emitting layer, it has a HOMO value larger than the Highly Occupied Molecular Orbital (HOMO) value of the light emitting layer, that is, excitation of the exciton, that is, hole blocking to prevent the movement of electrons and holes A layer must be formed.

Accordingly, the blue light emitting layer 270 is formed of a material having an energy level of the hole blocking layer, that is, a high Occupied Molecular Orbital (HOMO) energy level and a blue light emitting material. For example, the energy level of the hole blocking layer may be 2.75ev to 5.92ev. The blue light emitting layer 270 may suppress the movement of holes generated from the red light emitting layer 261 and the green light emitting layer 263, and may obtain the same effect as that of introducing a hole blocking layer, and to form the hole blocking layer. This reduces the number of processes, resulting in cost savings. In addition, the blue light emitting layer 270 is formed on the entire surface of the hole transport layer 240 in which the red and green light emitting layers 261 and 263 are formed, thereby eliminating the need for a fine pattern according to the blue light emitting layer 270, thereby reducing the patterning process. have.

The red, green, and blue light emitting layers 261, 263, and 270 are formed by any one of vacuum deposition, wet coating, ink jet, and laser thermal transfer.

The electron transport layer 280 is formed on the blue light emitting layer 270. The electron transport layer 280 allows electrons to be smoothly transported from the second electrode layer 290 to the red, green, and blue light emitting layers 261, 263, and 270. The electron transport layer 280 serves to increase the recombination opportunities in the red, green, and blue light emitting layers 261, 263, 270 by suppressing the movement of holes that do not combine with the holes in the red, green, and blue light emitting layers 261, 263, 270.

The second electrode layer 290 is formed on the electron transport layer 280. The second electrode layer 290 is formed of ITO, IZO, or the like, which are transparent electrodes.

Although not shown, an electron injection layer may be further formed between the electron transport layer 280 and the second electrode layer 290.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, according to the present invention, an auxiliary hole transport layer is formed between the red and green light emitting layers and the hole transport layer, respectively, thereby amplifying the color light luminance of the red and green wavelength bands and improving color purity. In addition, the blue light emitting layer having low luminous efficiency is entirely coated on the substrate on which the red and blue light emitting layers are formed, and is formed of a material having an energy level of the hole blocking layer, thereby eliminating the need for a fine pattern according to the blue light emitting layer, and forming the hole blocking layer. This reduces the number of processes resulting in cost savings.

Accordingly, a high resolution, high performance flexible display of a full color organic light emitting display device can be implemented.

Claims (14)

A conductive substrate having red, green and blue pixel regions, First electrode layers formed on the pixel region, respectively; A hole transport layer formed on the first electrode layer; An auxiliary hole transport layer formed on the hole transport layer and patterned in the red pixel area and the green pixel area at a position corresponding to the first electrode layer; A red light emitting layer formed by patterning a red light emitting material at a position corresponding to the red pixel region on the auxiliary hole transport layer; A green light emitting layer formed by patterning a green light emitting material at a position corresponding to the green pixel area; A blue light emitting layer formed of a blue light emitting material on an entire surface of the substrate on which the red light emitting layer and the green light emitting layer are formed; And a second electrode layer formed on the blue light emitting layer. The full color organic light emitting display device as claimed in claim 1, wherein the auxiliary hole transport layer is equal to an energy level of the hole transport layer. The full color organic light emitting display device as claimed in claim 2, wherein the energy level is 2.41ev to 5.45ev. The full color organic light emitting display device of claim 1, further comprising a hole injection layer and a hole transport layer on the substrate on which the first electrode layer is formed. The full color organic light emitting display device of claim 1, further comprising an electron transport layer between the blue light emitting layer and the second electrode layer. The full color organic light emitting display device of claim 1, wherein the conductive substrate is a metal thin film. The full color organic light emitting display device of claim 6, wherein the metal thin film is formed of stainless steel or titanium. The full color organic light emitting display device of claim 1, wherein the blue light emitting layer has an energy level of a hole blocking layer. The full color organic light emitting display device as claimed in claim 8, wherein the energy level is 2.75ev to 5.92ev. The full color organic light emitting display device as claimed in claim 8, wherein the blue light emitting layer has a thickness of about 100 μs to about 2000 μs. Stacking and patterning a first electrode layer on a conductive substrate defined by red, green, and blue pixel regions; Forming patterned auxiliary hole transport layers on the first electrode layers of the red and green pixel regions, respectively; Forming a red light emitting layer of the red pixel region and a green light emitting layer of the green pixel region at corresponding positions on the auxiliary hole transport layer; Forming a blue light emitting layer on an entire surface of the substrate on which the red light emitting layer and the green light emitting layer are formed; And forming a second electrode layer on the blue light emitting layer. 12. The method of claim 11, wherein the red, green, and blue light emitting layers are formed by one of vacuum deposition, wet coding, ink jet, and laser thermal transfer. 12. The method of claim 11, further comprising forming a hole injection layer and a hole transport layer on the substrate on which the first electrode layer is formed. The method of claim 11, further comprising forming an electron transport layer between the blue light emitting layer and the second electrode layer.

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