KR102078296B1 - Organic light emitting device - Google Patents

Abstract

The organic light emitting diode is disposed between a first electrode, a second electrode disposed to face the first electrode, the first electrode, and the second electrode to use holes and electrons provided from the first electrode and the second electrode. Organic light emitting layer to generate light, and an inorganic buffer layer disposed between the first electrode and the organic light emitting layer, wherein the inorganic buffer layer comprises a metal oxide.

Description

Organic light emitting element {ORGANIC LIGHT EMITTING DEVICE}

The present invention relates to an organic light emitting device.

Recently, Liquid Crystal Display, Organic Light Emitting Display, Electro Wetting Display Device, Plasma Display Panel (PDP) and Electrophoretic Display (Electrophoretic Display) Various display devices such as devices) are being developed.
Among the display devices, the organic light emitting display device is a self-emission type and does not require a separate light source. Therefore, there is an advantage of low power consumption. In addition, the organic light emitting display device has a fast response speed and excellent visibility and contrast ratio.
In general, the organic light emitting diode display includes an organic light emitting diode including an anode, an organic emission layer, and a cathode. In the organic light emitting device, holes and electrons are injected into the organic light emitting layer from the anode and the cathode, respectively, to form excitons, and the excitons are emitted while the excitons transition to the ground state.
The organic light emitting diode may emit light of white color or primary color. The white organic light emitting diode has a structure in which a light emitting layer is formed by stacking light emitting materials emitting three primary colors, for example, red, green, and blue light. The light emission is simultaneously performed in each of the stacked red, green, and blue light emitting layers, thereby achieving a balanced white light emission as a whole.

An object of the present invention to provide an organic light emitting device that can protect the organic layer.

An organic light emitting diode according to an embodiment of the present invention is disposed between a first electrode, a second electrode disposed to face the first electrode, the first electrode and the second electrode, and the first electrode and the second electrode. And an inorganic buffer layer disposed between the first electrode and the organic emission layer, wherein the inorganic buffer layer comprises a metal oxide.
The first electrode includes a first transparent electrode, a reflective electrode disposed on the first transparent electrode, and a second transparent electrode disposed on the reflective electrode, wherein the second electrode includes the second transparent electrode; And a third transparent electrode disposed to face each other.
The metal oxide includes any one of tungsten trioxide, molybdenum oxide, and niobium oxide.
The organic light emitting layer is disposed on the first electrode and is disposed on the first hole layer that transports holes injected from the first electrode, the first light emitting layer disposed on the first hole layer, and the first light emitting layer. A charge generation layer that generates electrons and holes, a second hole layer disposed on the charge generation layer to transport holes injected from the charge generation layer, a second light emitting layer disposed on the second hole layer, and And an electron transport layer disposed on the second light emitting layer to transport electrons injected from the second electrode.
The electron transport layer is doped with an n-type material.
The first light emitting layer is a red or green light emitting layer, and the second light emitting layer is a blue light emitting layer.
The first hole layer includes a first hole transport layer disposed on the first electrode and doped with a P-type material, and a second hole transport layer disposed on the first hole transport layer.
The second hole layer includes a third hole transport layer disposed on the charge generation layer and doped with a P-type material, and a fourth hole transport layer disposed on the third hole transport layer.

The organic light emitting device of the present invention can protect the organic layer.

1 is a view showing the structure of an organic light emitting device according to a first embodiment of the present invention.
2 illustrates a structure of an organic light emitting diode according to a second exemplary embodiment of the present invention.
3 is a cross-sectional view of a pixel including the organic light emitting diode illustrated in FIG. 1 or 2.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments are to make the disclosure of the present invention complete, and those of ordinary skill in the art to which the present invention belongs. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.
When elements or layers are referred to as "on" or "on" of another element or layer, intervening other elements or layers as well as intervening another layer or element in between It includes everything. On the other hand, when a device is referred to as "directly on" or "directly on" indicates that there is no intervening device or layer in between. “And / or” includes each and all combinations of one or more of the items mentioned.
The spatially relative terms " below "," beneath "," lower "," above "," upper " It can be used to easily describe the correlation of a device or components with other devices or components. Spatially relative terms are to be understood as terms that include different directions of the device in use or operation in addition to the directions shown in the figures. Like reference numerals refer to like elements throughout.
Although the first, second, etc. are used to describe various elements, components and / or sections, these elements, components and / or sections are of course not limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Therefore, the first element, the first component, or the first section mentioned below may be a second element, a second component, or a second section within the spirit of the present invention.
Embodiments described herein will be described with reference to plan and cross-sectional views, which are ideal schematic diagrams of the invention. Accordingly, shapes of the exemplary views may be modified by manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention are not limited to the specific forms shown, but also include changes in forms generated according to manufacturing processes. Accordingly, the regions illustrated in the figures have schematic attributes, and the shape of the regions illustrated in the figures is intended to illustrate a particular form of region of the device, and is not intended to limit the scope of the invention.
Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.
1 is a view showing the structure of an organic light emitting device according to a first embodiment of the present invention.
Referring to FIG. 1, the organic light emitting diode according to the first embodiment of the present invention is disposed between the first electrode 10, the second electrode 20, and the first electrode 10 and the second electrode 20. The organic light emitting layer 30 includes an inorganic buffer layer 40 disposed between the first electrode 10 and the organic light emitting layer 30.
The first electrode 10 may be an anode which is a hole injection electrode, and the second electrode 20 may be a cathode which is an electron injection electrode. In addition, the first electrode 10 may be defined as an anode electrode provided with a positive voltage, and the second electrode 20 may be defined as a cathode electrode provided with a negative voltage.
The first electrode 10 is formed of a reflective electrode. In detail, the first electrode 10 includes the first transparent electrode 11, the reflective electrode 12 disposed on the first transparent electrode 11, and the second transparent electrode disposed on the reflective electrode 12 ( 13).
The first transparent electrode 11 and the second transparent electrode 13 may include ITO, IZO, ZnO, or the like, which is a transparent conductive film. The reflective electrode 12 may include a reflective film formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound thereof. As an exemplary embodiment, the first and second transparent electrodes 11 and 12 may include ITO as shown in FIG. 1, and the reflective electrode 12 may include Ag as shown in FIG. 1. .
The second electrode 20 may include a third transparent electrode 20 which is a transparent conductive film. The third transparent electrode 20 may include ITO, IZO, ZnO, or the like, which is a transparent conductive film. As an exemplary embodiment, the third transparent electrode 20 may include ITO as shown in FIG. 1.
Electrons from the first electrode 10 and electrons from the second electrode 20 are injected into the organic light emitting layer 30 to form excitons, and the excitons emit light while transitioning to the ground state. That is, the organic light emitting layer 30 emits light by the voltages applied to the first electrode 10 and the second electrode 20.
The inorganic buffer layer 40 includes a metal oxide. For example, the inorganic buffer layer 40 may include any one of tungsten trioxide (WO 3), molybdenum oxide (MoO x), and niobium oxide (NbO x) as the metal oxide.
The inorganic buffer layer 40 is disposed on the organic light emitting layer 30 to protect the organic light emitting layer 30. Specifically, the organic light emitting layer 30 is formed by a thermal evaporation process. For example, the evaporated organic material is deposited in the pixel region defined as the region in which the organic light emitting element is formed to form the organic emission layer 30. After the organic light emitting layer 30 is formed, an inorganic buffer layer 40 is formed on the organic light emitting layer 30.
After the inorganic buffer layer 40 is formed, the second electrode 20 is formed on the inorganic buffer layer 40 by a sputtering process. For example, in a sputtering device, the gas ionized by the plasma impinges a sputtering target composed of a material to be deposited on the substrate. The sputtering target is made of a material for forming the second electrode 20. The sputtering material protruding from the sputtering target by the impact collides and deposits on the inorganic buffer layer 40.
When the inorganic buffer layer 40 is not used, the second electrode 10 is formed on the organic light emitting layer 30. In this case, when the sputtering material protruding from the sputtering target by the impact collides and is deposited on the organic light emitting layer 30, the organic light emitting layer 30 may be damaged by the collision. The damaged organic light emitting layer 30 may not emit light normally.
However, since the inorganic buffer layer 40 is disposed on the organic light emitting layer 30 and the sputtering material collides and is deposited on the inorganic buffer layer 40, damage to the organic light emitting layer 30 may be prevented.
The organic light emitting layer 30 includes the first hole layers 31 and 32, the first light emitting layer 33, the charge generating layer 34, the second hole layers 35 and 36, the second light emitting layer 37, and the electron transport layer. (ETL).
The first hole layers 31 and 32 are disposed on the first electrode 10, and the first light emitting layer 33 is disposed on the first hole layers 31 and 32. The first hole layers 31 and 32 transport holes injected from the first electrode 10. Specifically, holes injected from the first electrode 10 are transported to the first light emitting layer 33 through the first hole layers 31 and 32.
The first hole layers 31 and 32 are disposed on the first hole transport layer 31 and the first hole transport layer 31 disposed on the first electrode 10 by being doped with a P-type material to facilitate hole supply. A second hole transport layer 32.
The charge generating layer 34 is disposed on the first light emitting layer 33. Although not shown, the charge generation layer 34 may be formed by contact of the doped n-type layer and the p-type layer. The charge generating layer 34 generates electrons and holes. The charge generation layer 34 may inject electrons into the first emission layer 33 disposed under the direction in which the first electrode 10 is disposed. In addition, the charge generation layer 34 may inject holes into the second light emitting layer 37 disposed above the second electrode 20 in the direction in which the second electrode 20 is disposed.
The first emission layer 33 emits light using electrons injected from the hole and charge generation layer 34 injected from the first electrode 10. Specifically, holes and electrons are injected from the first electrode 10 and the charge generating layer 34 into the first light emitting layer 33 to form excitons, and the excitons are emitted while transitioning to the ground state. The first light emitting layer 33 may be a red or green light emitting layer.
The second hole layers 35 and 36 are disposed on the charge generation layer 34, and the second light emitting layer 37 is disposed on the second hole layers 35 and 36. The second hole layers 35 and 36 transport holes injected from the charge generation layer 34. Specifically, holes injected from the charge generation layer 34 are transported to the second light emitting layer 37 through the second hole layers 35 and 36.
The second hole layers 35 and 36 are disposed on the third hole transport layer 35 and the third hole transport layer 35 disposed on the charge generating layer 34 by being doped with a p-type material to facilitate hole supply. And a fourth hole transport layer 36.
The electron transport layer 38 is disposed on the second light emitting layer 37. The electron transport layer 38 transports the electrons injected from the second electrode 20. Specifically, electrons injected from the second electrode 20 are transported to the second light emitting layer 37 through the electron transport layer 38. The electron transport layer 38 may be doped with an n-type material to improve conductivity.
The second emission layer 37 emits light by holes injected from the charge generation layer 34 and electrons injected from the second electrode 20. Specifically, holes and electrons are injected from the charge generating layer 34 and the second electrode 20 into the second light emitting layer 37 to form excitons, and the excitons emit light while transitioning to the ground state. The second light emitting layer 37 may be a blue light emitting layer.
The inorganic buffer layer 40 is disposed on the electron transport layer 38 of the organic light emitting layer 30. The electron transport layer 38 is formed by a thermal evaporation process. For example, the evaporated organic material is deposited in the pixel region defined as the region in which the organic light emitting element is formed to form the electron transport layer 38. After the electron transport layer 38 is formed, the inorganic buffer layer 40 is formed on the electron transport layer 38.
After the inorganic buffer layer 40 is formed, the second electrode 10 is formed on the inorganic buffer layer 40 by a sputtering process. For example, in a sputtering device, the gas ionized by the plasma impinges a sputtering target composed of a material to be deposited on the substrate. The sputtering target is made of a material for forming the second electrode 20. The sputtering material protruding from the sputtering target by the impact collides and deposits on the inorganic buffer layer 40.
When the inorganic buffer layer 40 is not used, the second electrode 10 is formed on the electron transport layer 38 of the organic light emitting layer 30. In this case, when the sputtering material protruding from the sputtering target is deposited on the electron transporting layer 38 during the sputtering process, the electron transporting layer 38 may be damaged by the collision.
However, since the inorganic buffer layer 40 is disposed on the electron transport layer 38, and the sputtering material collides and is deposited on the inorganic buffer layer 40, damage to the electron transport layer 38 can be prevented.
As a result, the organic light emitting diode OLED according to the first embodiment of the present invention may protect the organic layer.
2 illustrates a structure of an organic light emitting diode according to a second exemplary embodiment of the present invention.
Referring to FIG. 2, the first light emitting layer 33 may be a blue light emitting layer. The second light emitting layer 37 may be a red or green light emitting layer. Except that the configurations of the first light emitting layer 33 and the second light emitting layer 37 are different, the configuration of the organic light emitting diode OLED illustrated in FIG. 2 is substantially the same as that of the organic light emitting diode OLED illustrated in FIG. 1. Same as Therefore, description of other components of the organic light emitting diode OLED shown in FIG. 2 is omitted.
3 is a cross-sectional view of a pixel including the organic light emitting diode illustrated in FIG. 1 or 2. The organic light emitting diode display includes a plurality of pixels illustrated in FIG. 3.
Referring to FIG. 3, the pixel PX includes a thin film transistor TFT formed on the substrate 111 and an organic light emitting diode OLED driven by the thin film transistor TFT.
Specifically, the buffer layer 112 is formed on the substrate 111. The semiconductor layer SM of the thin film transistor TFT is formed on the buffer layer 112. The semiconductor layer SM may be formed of an organic semiconductor or a semiconductor of an inorganic material such as amorphous silicon or polysilicon. In addition, the semiconductor layer SM may be formed of an oxide semiconductor. Although not illustrated, the semiconductor layer SM may include a source region, a drain region, and a channel region between the source region and the drain region.
The gate insulating layer 113 is formed to cover the semiconductor layer SM. The gate electrode GE of the thin film transistor TFT overlapping with the semiconductor layer SM is formed on the gate insulating layer 113. In more detail, the gate electrode GE may be formed to overlap the channel region of the semiconductor layer SM. The gate electrode GE is connected to a gate line (not shown) that applies an on / off signal to the thin film transistor TFT.
An interlayer insulating layer 114 is formed to cover the gate electrode GE. The source electrode SE and the drain electrode DE of the thin film transistor TFT are spaced apart from each other on the interlayer insulating layer 114. The source electrode SE may be connected to the semiconductor layer SM through the first contact hole H1 formed through the gate insulating layer 113 and the interlayer insulating layer 114. In more detail, the source electrode SE is connected to the source region of the semiconductor layer SM. The drain electrode DE may be connected to the semiconductor layer SM through the second contact hole H2 formed through the gate insulating layer 113 and the interlayer insulating layer 114. In detail, the drain electrode DE is connected to the drain region of the semiconductor layer SM.
The passivation layer 115 is formed to cover the source electrode SE and the drain electrode DE of the thin film transistor TFT. The first electrode 10 is formed on the passivation layer 115. The first electrode 10 may be connected to the drain electrode DE of the thin film transistor TFT through the third contact hole H3 formed through the passivation layer 115.
The pixel defining layer PDL is formed on the passivation layer 115. In detail, the pixel defining layer PDL includes an opening OP exposing the first electrode 10. The region formed by the opening OP may be defined as a pixel region. The pixel defining layer PDL may be formed to cover the boundary surface of the first electrode 10, and the opening OP of the pixel defining layer PDL may expose a predetermined region of the first electrode 10. . The pixel defining layer PDL may be formed of an organic insulating layer. However, the present invention is not limited thereto, and the inorganic insulating layer and the organic insulating layer may be sequentially stacked.
The organic emission layer 30 is formed on the first electrode 10 in the opening OP of the pixel defining layer PDL, and the inorganic buffer layer 40 is formed on the organic emission layer 30. The second electrode 20 is formed on the pixel defining layer PDL and the inorganic buffer layer 40.
The first electrode 11 may be formed as a reflective electrode, and the second electrode 13 may be formed as a transparent electrode.
The driving power for emitting the organic light emitting layer 30 of the organic light emitting diode OLED is applied to the first electrode 10 by the thin film transistor TFT, and the power having the opposite polarity to the driving power is applied to the second electrode 20. Is applied to. In this case, holes and electrons injected into the organic emission layer 30 combine to form excitons, and the organic light emitting element 10 emits light while the excitons transition to the ground state. White light may be generated by a combination of the light generated in the first light emitting layer 33 and the second light emitting layer 37.
The light L generated by the organic emission layer 30 is reflected by the first electrode 10 to emit light upward through the second electrode 20, which is a transparent electrode. In detail, the light L generated by the organic emission layer 30 is reflected by the reflective electrode 12 of the first electrode 10 to emit light in an upper direction.
Although described with reference to the embodiments, it will be understood by those skilled in the art that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be. In addition, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, and all technical ideas within the scope of the following claims and equivalents thereof should be construed as being included in the scope of the present invention. .

10: first electrode 20: second electrode
30: organic light emitting layer 40: inorganic buffer layer
11: first transparent electrode 12: reflective electrode
13: second transparent electrode 31: first hole transport layer
32: second hole transport layer 33: first light emitting layer
34: charge generating layer 35: third hole transport layer
36: fourth hole transport layer 37: second emission layer
38: electron transport layer OLED: organic light emitting device

Claims (9)

A first electrode;
A second electrode disposed to face the first electrode;
An organic emission layer disposed between the first electrode and the second electrode to generate light using holes and electrons provided from the first electrode and the second electrode; And
An inorganic buffer layer disposed between the second electrode and the organic light emitting layer,
The inorganic buffer layer includes a metal oxide,
The organic light emitting layer,
A first hole layer disposed on the first electrode and transporting holes injected from the first electrode;
A first light emitting layer disposed on the first hole layer;
A charge generation layer disposed on the first emission layer to generate electrons and holes;
A second hole layer disposed on the charge generating layer to transport holes injected from the charge generating layer;
A second light emitting layer disposed on the second hole layer; And
An electron transport layer disposed on the second light emitting layer to transport electrons injected from the second electrode,
The inorganic buffer layer is disposed between the second electrode and the electron transport layer, the inorganic buffer layer is disposed in direct contact with the upper surface of the electron transport layer. The method of claim 1,
The first electrode,
A first transparent electrode;
A reflective electrode disposed on the first transparent electrode; And
A second transparent electrode disposed on the reflective electrode,
The second electrode includes a third transparent electrode disposed to face the second transparent electrode. The method of claim 1,
And the metal oxide includes any one of tungsten trioxide, molybdenum oxide, and niobium oxide. delete The method of claim 1,
The electron transport layer is an organic light emitting device doped with an n-type material. The method of claim 1,
The first light emitting layer is a red or green light emitting layer, the second light emitting layer is an organic light emitting device. The method of claim 1,
Wherein the first light emitting layer is a blue light emitting layer, and the second light emitting layer is a red or green light emitting layer. The method of claim 1,
The first hole layer,
A first hole transport layer disposed on the first electrode and doped with a P-type material; And
An organic light emitting device comprising a second hole transport layer disposed on the first hole transport layer. The method of claim 1,
The second hole layer,
A third hole transport layer disposed on the charge generating layer and doped with a P-type material; And
An organic light emitting device comprising a fourth hole transport layer disposed on the third hole transport layer.

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