KR100685405B1 - Organic light emitting display - Google Patents

Abstract

The present invention relates to an organic light emitting display device, wherein the organic light emitting display device includes a first electrode, at least a hole injection layer, a hole transport layer, an organic film having a light emitting layer, and a second electrode, wherein the hole injection layer and the hole transport layer are formed. It is a technology that can be formed to a thickness having an optimal color coordinate to improve the luminous efficiency and electrical characteristics of the device.

Hole injection layer, hole transport layer

Description

Organic light emitting display device

1 is a cross-sectional view of an organic light emitting display device according to the present invention.

FIG. 2 is a sectional view schematically showing the structure of the organic film shown in FIG. 1. FIG.

<Explanation of symbols for main parts of the drawings>

100: insulating substrate 110: buffer film

120 polycrystalline silicon layer pattern 122 source region

124: drain region 130: gate insulating film

132: gate electrode 140: interlayer insulating film

150 source electrode 152 drain electrode

160: protective film 170: planarization film

180: pixel electrode 190: pixel defining layer pattern

200: organic film 201: hole injection layer

202: hole transport layer 203: light emitting layer

204: electron transport layer 205: electron injection layer

210: counter electrode

The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device having a hole injection layer and a hole transport layer having an optimal thickness showing an optimal color coordinate.

The organic light emitting device is a self-luminous display, which has a thin, lightweight, simple parts, an ideal structure, a simple structure, a wide viewing angle in high definition, perfect video, high color purity, low power consumption, and low voltage driving. It has the advantage of having suitable electrical properties.

In general, an organic light emitting display device has a substrate and a pixel electrode on the substrate, an organic layer including an emission layer (EML) on the pixel electrode, and an opposite electrode on the organic layer. The organic layer may include a hole injection layer (HIL) and a hole transport layer (HTL) between the pixel electrode and the light emitting layer, and an electron transfer layer (ETL) and an electron injection layer between the light emitting layer (EML) and the counter electrode. It may further include an injection layer (EIL).

The driving principle of the organic light emitting display device having the above structure is as follows. When a voltage is applied between the pixel electrode and the counter electrode, holes are injected from the pixel electrode into the light emitting layer via the hole injection layer and the hole transport layer, and electrons are also injected into the light emitting layer from the counter electrode via the electron injection layer and the electron transport layer. . Holes and electrons injected into the emission layer recombine in the emission layer to generate excitons, and the excitons emit light while transitioning from the excited state to the ground state.

In general, the front emission type organic light emitting display device uses the resonance effect of light, so it is important to form the thickness of the pixel electrode to match the wavelength range where possible, and the thickness of the hole injection layer and the hole transport layer provided between the light emitting layer and the pixel electrode may be It is also important to form accordingly. The hole injection layer facilitates the injection of holes from the pixel electrode, which is an anode, thereby improving the power consumption efficiency of the device and increasing the life of the device. The hole transport layer easily transports holes, binds electrons to a light emitting region, increases the probability of forming excitons, and has high hole mobility. In order for the organic electroluminescent display to have NTSC color coordinates, the hole injection layer and the hole transport layer should be formed to an appropriate thickness. However, when the hole injection layer and the hole transport layer are formed too thick, there is a problem in that the driving voltage is increased and power consumption is increased.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above-described problems of the related art, and to provide an organic light emitting display device capable of improving color purity and power consumption in consideration of color coordinates and luminance of blue light.

In order to achieve the above technical problem the organic light emitting display device according to the present invention,

A pixel electrode provided on the insulating substrate, an organic film provided on the pixel electrode and including at least a hole injection layer, a hole transport layer and a light emitting layer, and an opposite electrode provided on the organic film,

The sum of the thickness of the pixel electrode, the hole injection layer, and the hole transport layer is 1400 to 1600Å.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

FIG. 1 is a cross-sectional view of an organic light emitting display device according to the present invention, and FIG. 2 is a cross-sectional view schematically showing the structure of the organic film shown in FIG.

Referring to FIG. 1, an organic light emitting display device includes a thin film including source / drain electrodes 150 and 152 connected to a gate electrode 132 and source / drain regions 122 and 124 on an insulating substrate 100. An organic layer 200 including at least a light emitting layer on the pixel electrode 180 and the pixel electrode 180 connected to any one of a transistor and the source / drain electrodes 150 and 152, and an upper portion of the organic layer 200. It consists of a counter electrode 210 provided in.

Referring to FIG. 2, the organic layer 200 includes at least a hole injection layer 201, a hole transport layer 202, and a light emitting layer 203, and includes an electron transport layer 204, an electron injection layer 205, and a hole suppression layer. It may further comprise one or more of the layers (not shown). Here, the light emitting layer 203 emits blue light.

Currently, the color coordinates of blue light in the front-emitting organic light emitting display device are (0.14, 0.07), which is the level of the National Television System Committee (NTSC).

In order for the blue light to have NTSC level color coordinates, it is important to adjust the thicknesses of the hole injection layer 201 and the hole transport layer 202 to an optimal thickness.

The thickness of the pixel electrode 180 is 100 to 150 kPa, preferably 125 kPa, and when the thickness of the hole injection layer 201 is 1000 to 1300 kPa, the thickness of the hole transport layer 202 is within a range of 100 to 400 kPa. In the case of adjusting the thickness of the hole injection layer 201 to 300 ~ 500Å, the thickness of the hole transport layer 202 is adjusted within the range of 800 to 1000Å. In addition, the total thickness of the pixel electrode 180, the hole injection layer 201 and the hole transport layer 202 is adjusted within the range of 1400 to 1600Å. The total thickness range of the pixel electrode 180, the hole injection layer 201, and the hole transport layer 202 may vary slightly depending on the deposition equipment or the type of deposition material.

By adjusting the thickness of the pixel electrode 180, the hole injection layer 201 and the hole transport layer 202 as described above, the color coordinate of the blue light is adjusted within the range of x value of 0.13 to 0.15, y value of 0.06 to 0.08. Be sure to

A method of manufacturing an organic light emitting display device according to an embodiment of the present invention is as follows.

A thin film transistor including a gate electrode 132 and source / drain electrodes 150 and 152 is formed on the insulating substrate 100, and one of the source / drain electrodes 150 and 152 and the drain electrode 152 is formed. Pixel electrode 180 is formed. Here, the pixel electrode 180 is formed of a transparent electrode having a reflective film under the pixel electrode 180.

Next, an organic layer 200 including at least a hole injection layer 201, a hole transport layer 202, and a light emitting layer 203 is formed on the light emitting region of the pixel electrode 180. The organic layer 200 may further include at least one thin film among the hole suppression layer (not shown), the electron transport layer 204, and the electron injection layer 205.

Next, the counter electrode 210 is formed on the organic layer 200.

Subsequently, an organic light emitting display device is completed by bonding an encapsulation substrate (not shown) to an upper portion of the cutoff plate 100 including the pixel electrode 180, the organic layer 200, and the counter electrode 210.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Examples 1 and 2 are examples of fabricating an organic light emitting display device for measuring color coordinate values of blue light according to the present invention.

<Example 1>

A 125-kV pixel electrode was formed on the insulating substrate. Thereafter, a hole injection layer was formed on the pixel electrode to a thickness of 1000 GPa, and a hole transport layer was formed on the hole injection layer to a thickness of 400 GPa. Next, a light emitting layer emitting blue light was formed on the hole transport layer. Next, an electron transport layer, an electron injection layer, and an opposite electrode were formed on the emission layer, and an absorbent and an encapsulation substrate were adhered to the insulating substrate to manufacture an organic light emitting display device.

The color coordinates of the organic light emitting display device were measured as (0.1358, 0.0645).

<Example 2>

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed at 400 GPa and the hole transport layer was formed at 900 GPa.

The color coordinates of the organic light emitting display device were measured as (0.1371, 0.0685).

Comparative Example 1

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed at 1000 mW and the hole transport layer was formed at 300 mW.

The color coordinates of the organic light emitting display device were measured as (0.1486, 0.0379).

Comparative Example 2

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed at 1000 mW and the hole transport layer was formed at 500 mW.

The color coordinates of the organic light emitting display device were measured as (0.1176, 0.1258).

Comparative Example 3

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed at 400 GPa and the hole transport layer was formed at 800 GPa.

The color coordinates of the organic light emitting display device were measured as (0.1458, 0.0398).

<Comparative Example 4>

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed at 400 GPa and the hole transport layer was formed at 1000 GPa.

The color coordinates of the organic light emitting display device were measured as (0.1212, 0.1027).

Table 1 shows color coordinate values of the organic light emitting display devices manufactured according to Examples 1 and 2 and Comparative Examples 1, 2, 3, and 4. The pixel electrode of the organic light emitting display device has a color coordinate value of blue light at 125 GHz.

Item Hole injection layer Hole transport layer Color coordinates (NTSC) (0.14, 0.07) Example 1 1000 400 (0.1358, 0.0645) Example 2 400 900 (0.1371, 0.0685) Comparative Example 1 1000 300 (0.1486, 0.0379) Comparative Example 2 1000 500 (0.1176, 0.1258) Comparative Example 3 400 800 (0.1458, 0.0398) Comparative Example 4 400 1000 (0.1212, 0.1027)

As a result of comparing Example 1, Comparative Example 1, and Comparative Example 2 with reference to Table 1, the color coordinates of the blue light were close to the NTSC level when the hole transport layer is 400 경우 when the thickness of the hole injection layer is 1000 Å. In addition, as a result of comparing Example 2, Comparative Example 3 and Comparative Example 4, the color coordinate of the blue light was close to the NTSC level when the thickness of the hole injection layer is 400 Å, the thickness of the hole transport layer is 900 Å. Since the thickness may vary slightly depending on the type of deposition equipment or deposition material, the total thickness range of the pixel electrode 180, the hole injection layer 201, and the hole transport layer 202 is set at 1400-1600 Å.

In addition, even if the total thickness of the pixel electrode 180, the hole injection layer 201 and the hole transport layer 202 is approximately 1400 ~ 1600Å, the structure where the hole injection layer and the hole transport layer are 1000 + 400Å and 400 + 1000Å They may have the same but different color coordinate values because of an incorrect electrical charge balance.

As described above, in the present invention, the hole injection layer and the hole transport layer are formed to have a thickness in which blue light has an optimal color coordinate, thereby improving color purity and luminance of the blue light and reducing power consumption.

Claims (11)

A pixel electrode provided on the insulating substrate, an organic film provided on the pixel electrode and including at least a hole injection layer, a hole transport layer and a light emitting layer, and an opposite electrode provided on the organic film, And a sum of the thicknesses of the pixel electrode, the hole injection layer, and the hole transport layer is 1400 to 1600 두께. The method of claim 1, The pixel electrode has a thickness of 100 to 150 두께. The method of claim 1, And the pixel electrode has a thickness of 125 GHz. delete The method of claim 4, wherein The hole injection layer has a thickness of 1000 kPa, and the hole transport layer has a thickness of 400 kPa organic light emitting display device. The method of claim 1, The hole injection layer has a thickness of 300 to 500 kPa, and the hole transport layer has a thickness of 800 to 1000 kPa organic light emitting display device. The method of claim 6, And the hole injection layer has a thickness of 400 kPa, and the hole transport layer has a thickness of 900 kPa. The method of claim 1, And at least one thin film transistor electrically connected to the pixel electrode between the insulating substrate and the pixel electrode. The method of claim 1, And the organic layer further comprises at least one of a hole suppression layer, an electron transport layer, and an electron injection layer. The method of claim 1, The light emitting layer is an organic light emitting display device, characterized in that for emitting blue light. The method according to claim 1 or 10, The color coordinate of the organic light emitting display device is an organic light emitting display device, characterized in that x value is 0.13 to 0.15, y value is 0.06 to 0.08.

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