KR101970491B1 - Organic electro-luminescence display device - Google Patents

Abstract

The present invention discloses an organic light emitting display. The organic electroluminescent display device of the present invention includes: a substrate; A thin film transistor formed on the substrate, first and second capacitor electrodes; An interlayer insulating film and a protective layer formed on the substrate on which the thin film transistor is formed; A pixel electrode formed on the protective layer; An organic layer formed on the substrate on which the pixel electrode is formed to expose the pixel electrode; An organic light emitting diode formed on the exposed pixel electrode; And a capping layer formed on the organic light emitting diode and having an inorganic material and an organic material mixed.
The organic light emitting display of the present invention has an effect of improving the light efficiency and the viewing angle by forming a capping layer in which an inorganic material and an organic material are mixed on the organic light emitting layer.

Description

[0001] Organic electro-luminescence display device [0002]

The present invention relates to an organic light emitting display having improved light efficiency and viewing angle.

The organic electroluminescence display device includes an anode, a cathode, and an organic light emitting layer interposed between the two electrodes. In such an organic light emitting display, an image is realized by recombining holes and electrons provided in the anode and the cathode, respectively, in the organic light emitting layer to generate light.

As a result, the organic light emitting display device is self-luminous and does not require a backlight such as a liquid crystal display device, so that it can be made light and thin, and can be manufactured through a simple process, thereby improving price competitiveness. In addition, since the organic light emitting display device has a low voltage driving, a high luminous efficiency, and a wide viewing angle, it has rapidly increased as a next generation display.

The organic light emitting display device may further include a hole transport layer and an electron transport layer between the anode and the organic light emitting layer and between the cathode and the organic light emitting layer to efficiently inject holes and electrons into the organic light emitting layer, So as to improve the luminous efficiency.

The organic light emitting display device has a problem that the light efficiency is lowered due to various causes. Particularly, the outgas generated in the organic light emitting layer during the manufacturing process of the organic light emitting display may not be diffused to the outside, or optical distortion occurs in a plurality of layers stacked on the organic light emitting layer, thereby lowering the light efficiency.

Also, even if the layers on the organic light emitting layer do not have uniform uniformity or layers of a certain thickness are laminated, there is a problem that the light efficiency is lowered according to the refractive index of the layers present on the organic light emitting layer depending on the type of light wavelength have.

An object of the present invention is to provide an organic electroluminescent display device in which a capping layer in which an inorganic material and an organic material are mixed is formed on an organic light emitting layer to improve a light efficiency and a viewing angle.

It is another object of the present invention to provide an organic light emitting display having improved light efficiency and viewing angle by forming a capping layer having a higher refractive index (n) than the organic light emitting layer on the organic light emitting layer.

According to an aspect of the present invention, there is provided an organic light emitting display including: a first electrode; An organic light emitting layer including an organic electroluminescent material on the first electrode; A second electrode on the organic light emitting layer; And a capping layer in which an inorganic material and an organic material are mixed on the second electrode.

Further, an organic light emitting display device of the present invention includes: a substrate; A thin film transistor formed on the substrate, first and second capacitor electrodes; An interlayer insulating film and a protective layer formed on the substrate on which the thin film transistor is formed; A pixel electrode formed on the protective layer; An organic layer formed on the substrate on which the pixel electrode is formed to expose the pixel electrode; An organic light emitting diode formed on the exposed pixel electrode; And a capping layer formed on the organic light emitting diode and having an inorganic material and an organic material mixed.

The organic light emitting display of the present invention has an effect of improving the light efficiency and the viewing angle by forming a capping layer in which an inorganic material and an organic material are mixed on the organic light emitting layer.

In addition, the organic light emitting display of the present invention has an effect of improving the light efficiency and the viewing angle by forming a capping layer having a higher refractive index (n) than the organic light emitting layer on the organic light emitting layer.

1 is a cross-sectional view of an organic light emitting display device according to the present invention.
2 is a graph showing the refractive index characteristics of the capping layer used in the organic light emitting display of the present invention.
3 is a graph showing the light efficiency characteristics of the capping layer used in the organic light emitting display of the present invention.
4 is a specific sectional view of a display device to which a capping layer is applied according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

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

1, the organic light emitting display of the present invention includes an organic light emitting diode (OLED) including a cathode 110, an organic light emitting layer 120, and an anode 130 on a substrate 101 A capping layer 140 and an encapsulation layer 150 are formed on the second electrode 130 of the organic light emitting diode in which organic and inorganic materials are mixed.

The organic light emitting layer 120 may be formed of an organic material that generates white light or may be formed of red (R), green (G), and blue (B) organic materials. In addition, the organic light emitting layer 120 may further include a plurality of charge transporting layers, and the charge transporting layers may be formed of materials for transporting electrons or holes.

The first electrode 110 may use a conductive material having a work function smaller than that of the second electrode 130 and may be Mg, Ca, Al, Ag, Li, or an alloy thereof.

The second electrode 130 may be made of a transparent material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

In addition, the capping layer 140 of the present invention may be formed of a layer in which an organic material and an inorganic material are mixed. The inorganic material includes inorganic metal-containing materials and inorganic materials that do not contain a metal. Exemplary inorganic materials that do not contain a metal can be, for example, C, Ge, Si, SiO, SiO2, or Si3N4.

The inorganic metal-containing materials include, for example, metal oxides such as MgO, Li2O, CaO, Cs2O, Al2O3, In2O3, Cr2O3, CuO, Cu2O, ZnO, ZrO2 and SnO2; Metal hydrides such as Mg2 (OH), Ca2 (OH), LiOH, KOH, Cr (OH) 3 and NaOH; metal halides such as LiF, CsF, MgF2, KF, and FeCl3; Cu, Ti, Pd, and Pt (e.g., ZnS), metal nitrides (e.g., TiSiN and TaN), metal silicides (e.g., WSi), elemental metals such as Ag, Fe, Zn, Mg, Cr, Au, ) And a metal alloy (for example, Mg-Ag alloy, Li-Al alloy, Au-Pd alloy, Au-Pt alloy, Pt-Pd alloy a and Pd-Ag alloy).

 The organic material may also include, for example, copper phthalocyanine; Copper tetramethyl phthalocyanine; Zinc phthalocyanine; Titanium oxide phthalocyanine; Tertiary aromatic amine derivatives including substances such as magnesium phthalocyanine and the like, indolecarbazole derivatives, and hole transporting materials such as porphyrin derivatives.

If the inorganic material to be mixed in the capping layer 140 is inorganic metal, the inorganic material may be mixed in a ratio of 1% to 10% of the organic material. The thickness of the capping layer 140 may range from 100 to 1000 Å, and the refractive index n may range from 1.7 to 2.5.

The substrate 101 may be an array substrate on which TFTs, gate lines, and data lines are formed.

FIG. 2 is a graph showing the refractive index characteristics of the capping layer used in the organic electroluminescence display of the present invention, and FIG. 3 is a graph showing the light efficiency characteristics of the capping layer used in the organic light emitting display of the present invention.

Referring to FIGS. 2 and 3, the refractive index change and absorbance (k) characteristics are shown while controlling the content of Ag, which is an inorganic metal, in the capping layer of the organic light emitting display of the present invention.

As can be seen, the refractive index increases in the visible light wavelength region as the Ag content of the capping layer increases from 0 to 5%. Also, it can be seen that the absorbance (k) also increases in the visible light wavelength region according to the Ag content.

The absorbance k is also referred to as optical density. When the energy radiation such as light is irradiated to a substance, the ratio I2 / I2 of the radiation amount I2 to the transmitted radiation amount I1, I1). That is, when the absorbance k increases, the radiation efficiency increases because the radiation emitted from the organic light emitting layer increases while transmitting through the capping layer.

The increase in the refractive index of the capping layer is also refracted in the capping layer having a high refractive index, thereby improving the viewing angle characteristics.

4 is a specific sectional view of a display device to which a capping layer is applied according to the present invention.

Referring to FIG. 4, the organic light emitting display device including the capping layer illustrated in FIGS. 1 to 3 may be directly applied to a display device.

The display device of the present invention is characterized in that a buffer layer 211 is formed on a substrate 210 and a thin film transistor and first and second capacitor electrodes 221 and 251 are formed on the buffer layer 211.

The thin film transistor includes a semiconductor layer 231 including a source region 231a, a channel region 231b and a drain region 231c, a gate insulating film 240, a gate electrode 250, An electrode 219a and a drain electrode 219b are formed. The source electrode 219a and the drain electrode 219b are connected to the source region 231a and the drain region 231c of the semiconductor layer 231, respectively. The capacitor region is formed of a capacitor first electrode 221, a gate insulating film 240, a capacitor second electrode 251, an interlayer insulating film 260, and a protective layer 261.

The source / drain electrodes 219a and 219b may be formed of a single layer or a stacked structure using an insulating layer such as a silicon oxide layer or a silicon nitride layer. The source / drain electrodes 219a and 219b may be formed of a metal such as molybdenum (Mo), titanium (Ti) Any one of tantalum (Ta), tungsten (W), copper (Cu), chromium (Cr), aluminum (Al) In addition, a transparent conductive material such as indium tin oxide (ITO) may be used. In the drawings, a single metal layer is formed. In some cases, however, at least two metal layers may be stacked.

The gate electrode 250 may be formed of a metal such as molybdenum (Mo), titanium (Ti), tantalum (Ta), tungsten (W), copper (Cu), chromium (Cr), aluminum It may be formed by laminating at least one of ITO, IZO and ITZO which are transparent conductive materials.

A pixel electrode 220 electrically connected to the drain electrode 219b by a contact hole is formed on the passivation layer 261. [

An organic layer 270 is formed on a front surface of the substrate 210 on which the pixel electrode 220 is formed and a contact hole exposing the pixel electrode 220 is formed on the organic layer 270. A lower electrode 290 of the organic light emitting diode OLED is formed on the exposed pixel electrode 220. An organic light emitting layer 291 is formed on the lower electrode 290 and an upper electrode 292 is formed on the organic light emitting layer 291.

The organic light emitting layer 291 may include a hole injection layer, a hole transporting layer, a light emitting material layer, a light emitting material layer, , An electron transporting layer, and an electron injection layer.

The organic light emitting diode may be driven by a top emission type in which light emitted from the organic emission layer 291 is emitted toward the upper electrode 292.

When the organic light emitting diode OLED is formed on the substrate 210 as described above, the capping layer 340 and the sealing layer 350 (see FIG. 1) ).

1, since the capping layer 340 has high refractive index and absorbance characteristics in the visible light region due to the mixing of the organic material and the inorganic material, a large amount of light generated in the organic light emitting diode (OLED) And the viewing angle is improved by the high refractive index characteristic of the capping layer.

101: substrate 110: first electrode
120: organic light emitting layer 130: second electrode
140: capping layer 150: sealing layer

Claims (13)

A first electrode;
An organic light emitting layer including an organic electroluminescent material and formed on the first electrode to emit light upward;
A second electrode formed on the organic light emitting layer; And
And a capping layer in which an inorganic material and an organic material are mixed on the second electrode,
Wherein the second electrode is made of a light-transmitting oxide, and the inorganic material constituting the capping layer is made of a metal alloy containing Ag. The organic electroluminescent display device according to claim 1, wherein the ratio of the inorganic material to the organic material is 1 to 5%.
The organic light emitting display as claimed in claim 1, wherein the capping layer has a thickness of 100 to 1000 ANGSTROM.
The organic electroluminescent display device according to claim 1, wherein the refractive index of the capping layer is 1.7 to 2.5.
The organic electroluminescent display device according to claim 1, wherein the inorganic material of the capping layer further comprises one of Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd, .
Board;
A thin film transistor formed on the substrate, first and second capacitor electrodes;
An interlayer insulating film and a protective layer formed on the substrate on which the thin film transistor is formed;
A pixel electrode formed on the protective layer;
An organic layer formed so that a part of the pixel electrodes are exposed so as not to vertically overlap with the thin film transistor, the first and second capacitor electrodes;
An organic light emitting diode including a lower electrode, an organic light emitting layer, and an upper electrode, the organic light emitting diode being formed on the exposed pixel electrode and emitting light upward; And
A capping layer formed on the organic light emitting diode and having an inorganic material and an organic material mixed,
Wherein the upper electrode is made of a light-transmitting oxide, and the inorganic material constituting the capping layer is made of a metal alloy containing Ag.
delete The organic light emitting display as claimed in claim 6, wherein the ratio of the inorganic material to the organic material is 1 to 5%.
7. The organic light emitting display as claimed in claim 6, wherein the capping layer has a thickness of 100 to 1000 ANGSTROM.
7. The organic light emitting display as claimed in claim 6, wherein the refractive index of the capping layer is 1.7 to 2.5.
7. The organic electroluminescent display device according to claim 6, wherein the inorganic material of the capping layer further comprises any one of Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd and Pt. .
7. The organic electroluminescent display device according to claim 6, wherein the transparent oxide forming the upper electrode is indium tin oxide (ITO) or indium zinc oxide (IZO).
The organic electroluminescent display device according to claim 1, wherein the light-transmitting oxide of the second electrode is indium tin oxide (ITO) or indium zinc oxide (IZO).

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