KR101773610B1 - Method manufacturing of organic light emitting diode - Google Patents

Abstract

A method of fabricating an organic electroluminescent device according to an embodiment of the present invention includes forming a first electrode on a substrate, forming a source in which a hole transporting material and an electron transporting material are sequentially arranged on the substrate on which the first electrode is formed Transporting material is arranged in such a manner that the source is heated and scanned once to form a hole transporting layer on the first electrode and a light emitting layer and an electron transporting layer which are a mixed layer of the hole transporting material and the electron transporting material, And forming a second electrode on the light emitting layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an organic electroluminescent device,

The present invention relates to an organic electroluminescent device, and more particularly, to a method of manufacturing an organic electroluminescent device.

2. Description of the Related Art In recent years, the importance of flat panel displays (FPDs) has been increasing with the development of multimedia. In response to this, various kinds of devices such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic light emitting device A flat display of a flat panel display has been put into practical use.

Particularly, the organic electroluminescent device has a response speed of 1 ms or less, a high response speed, low power consumption, and self-emission. In addition, there is no problem in the viewing angle, which is advantageous as a moving picture display medium regardless of the size of the apparatus. In addition, since it can be manufactured at a low temperature and the manufacturing process is simple based on the existing semiconductor process technology, it is attracting attention as a next generation flat panel display device.

The organic electroluminescent device includes a light emitting layer between the anode and the cathode, and the holes supplied from the anode and the electrons received from the cathode combine in the light emitting layer to form an exciton as a hole-electron pair. And the light is emitted by the generated energy.

However, the organic electroluminescent device has a great influence on the lifetime and the efficiency of the device depending on the materials used, the lamination structure, and the like. Therefore, research for developing an organic electroluminescent device having more excellent lifetime and efficiency is underway.

The present invention provides a method of manufacturing an organic electroluminescent device having excellent lifetime and light emitting efficiency.

According to an aspect of the present invention, there is provided a method of manufacturing an organic electroluminescent device, including: forming a first electrode on a substrate; forming a hole transporting material and an electron transporting material on the substrate, A step of preparing a source in which materials are sequentially arranged, scanning the source while heating the source in the direction in which the hole transporting material is disposed, and forming a hole transport layer on the first electrode, a mixed layer of the hole transport material and the electron transport material Emitting layer and an electron-transporting layer simultaneously, and forming a second electrode on the light-emitting layer.

The source may further include a green phosphorescent dopant material disposed between the hole transport material and the electron transport material and may deposit the dopant material simultaneously with the deposition of the hole transport material and the electron transport material.

The step of forming the hole transporting layer, the light emitting layer and the electron transporting layer, which are a mixed layer of the hole transporting material and the electron transporting material, may include: forming a hole transporting layer by first depositing the hole transporting material of the source on the substrate; The deposition of the electron transporting material of the source is started and the light emitting layer is formed by co-deposition of the hole transporting material and the electron transporting material and the electron transporting material is deposited, To form a transport layer.

The method may further include forming a hole injection layer on the first electrode before forming the hole transport layer.

And forming an electron injection layer on the electron transport layer before forming the second electrode.

The mixing ratio of the hole transporting material to the electron transporting material may be 1: 1.

The scan of the source may start at one side of the substrate and end at the other side of the substrate.

The organic electroluminescent device according to an embodiment of the present invention has an advantage that the luminescent efficiency and lifetime can be greatly improved by forming a luminescent layer having a mixing ratio of a hole transporting material and an electron transporting material of 1: 1. Further, there is an advantage that a hole transporting layer, a light emitting layer and an electron transporting layer can be easily formed through a process of scanning a source.

1 is a view illustrating an organic electroluminescent device according to an embodiment of the present invention.
2 is a view illustrating a deposition apparatus for manufacturing an organic electroluminescent device according to an embodiment of the present invention.
3 is a plan view of a source according to one embodiment of the present invention.
4A to 4C are views illustrating a method of manufacturing an organic electroluminescent device according to an embodiment of the present invention.
5 is a graph showing the lifetime of an organic electroluminescent device manufactured according to Example 1 of the present invention and a comparative example.
6 is a graph showing the lifetime of an organic electroluminescent device manufactured according to Embodiments 1, 2 and 3 of the present invention.

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

1 is a view illustrating an organic electroluminescent device according to an embodiment of the present invention.

1, an organic electroluminescent device 100 according to an embodiment of the present invention includes a substrate 110, a first electrode 120 disposed on the substrate 110, a first electrode 120, A hole transport layer 132 located on the hole injection layer 131, a light emitting layer 140 located on the hole transport layer 132, and a light emitting layer 140 formed on the light emitting layer 140. The hole injection layer 131, An electron injection layer 152 located on the electron transport layer 151 and a second electrode 160 located on the electron injection layer 152. The electron injection layer 152 may be formed of a metal such as Al,

The substrate 110 may be formed of glass, plastic, or metal. The substrate 110 may further include a thin film transistor including a semiconductor layer, a gate electrode, a source electrode, and a drain electrode.

The first electrode 120 may be a transparent electrode or a reflective electrode. When the first electrode 120 is a transparent electrode, the first electrode 120 may be one of indium tin oxide (ITO), indium zinc oxide (IZO), and zinc oxide (ZnO).

When the first electrode 120 is a reflective electrode, the first electrode 120 may be formed of any one of aluminum (Al), silver (Ag), and nickel (Ni) under the layer of any one of ITO, IZO, And may further include the reflective layer between two layers made of any one of ITO, IZO, and ZnO.

The first electrode 120 may be formed using a sputtering method, an evaporation method, a vapor phase deposition method, or an electron beam deposition method.

A hole injecting layer 131 and a hole transporting layer 132 are disposed on the first electrode 120. The hole injection layer 131 may function to smoothly inject holes from the first electrode 120 into the light emitting layer 140 and may be formed of cupper phthalocyanine (CuPc), poly (3,4) -ethylenedioxythiophene (PEDOT) , PANI (polyaniline) and NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine).

The hole injection layer 131 can be formed by evaporation or spin coating.

The hole transport layer 132 plays a role of facilitating the transport of holes and may be formed by using NPD (N-dinaphthyl-N, N'-diphenyl benzidine), TPD (N, N'- N, N'-bis- (phenyl) -benzidine), s-TAD, and MTDATA (4,4 ', 4 "-tris (N-3-methylphenyl-N-phenylamino) -triphenylamine) But it is not limited thereto.

The hole transporting layer 132 may be formed by an evaporation method or a spin coating method.

An emission layer 140 is disposed on the hole transport layer 132. The light emitting layer 140 may be a mixed layer of a hole transporting material and an electron transporting material. Here, the hole transporting material is made of hole transporting materials which facilitate transport of holes, and may be made of the same material as the above-described hole transporting layer, for example. In addition, the electron transport material is made of an electron transporting material which facilitates the transport of electrons. For example, in the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq and SAlq But the present invention is not limited thereto.

The light emitting layer 140 is a mixed layer of a hole transporting material and an electron transporting material. The mixing ratio of the hole transporting material and the electron transporting material is 1: 1. If the specific gravity of the hole transporting material and the electron transporting material in the light emitting layer 140 increases, the charges do not emit light at the interface between the hole transporting layer and the light emitting layer or the electron transporting layer and the light emitting layer, . Accordingly, in the present invention, the mixing ratio of the hole transporting material and the electron transporting material in the light emitting layer 140 is 1: 1.

The hole transporting material and the electron transporting material mixed in the light emitting layer 140 function as a host material of the light emitting layer 140, respectively. The light emitting layer 140 includes a green phosphorescent dopant. Examples of the green phosphorescent dopant include Ir (ppy) 2 (acac) and Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium).

An electron transport layer 151 is disposed on the light emitting layer 140. The electron transporting layer 151 may be made of the above-mentioned electron transporting material.

An electron injection layer 152 is located on the electron transport layer 151. The electron injection layer 152 serves to smoothly inject electrons and may use Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq. Further, the electron injection layer 152 may be made of an inorganic material, and the inorganic material may be a metal compound. For example, the electron injection layer 152 may comprise an alkali metal or alkaline earth metal, a metal compound comprising an alkali metal or alkaline earth metal is LiQ, LiF, NaF, KF, RbF, CsF, FrF, BeF _{2, MgF 2, CaF 2, SrF 2} , BaF 2 and RaF ₂ be at least one selected from the group consisting of, but not limited to this. The electron injection layer 152 may be formed using an evaporation method or a spin coating method, and the thickness of the electron injection layer 152 may be 1 to 50 nm.

The second electrode 160 is positioned on the electron injection layer 152. The second electrode 160 may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof having a low work function. Here, the second electrode 160 may be formed to have a thickness thin enough to transmit light when the organic electroluminescent device has a front or both-side light emitting structure, and when the organic electroluminescent device has a back light emitting structure, It can be formed thick enough to reflect light. As described above, the organic electroluminescent device 100 according to one embodiment of the present invention can be configured.

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

FIG. 2 is a view showing a deposition apparatus for manufacturing an organic electroluminescent device according to an embodiment of the present invention, and FIG. 3 is a plan view showing a source according to an embodiment of the present invention.

2 and 3, a deposition apparatus 300 includes a vacuum chamber 310, a substrate 110 fixed to the substrate plate 320, and a source 330 containing an evaporation material ). At this time, the source 330 can reciprocate in a predetermined direction.

On one side of the source 330, a hole transport material 340 is arranged on one side and an electron transport material 360 is arranged on the other side. A green phosphorescent dopant 350 is arranged between the electron transporting material 340 and the hole transporting material 360.

A manufacturing method of the organic electroluminescent device of the present invention will be described below with reference to process steps using the deposition apparatus 300 constructed as above.

4A to 4C are views illustrating a method of fabricating an organic electroluminescent device according to an embodiment of the present invention.

Referring to FIG. 4A, after the first electrode and the hole injection layer are formed on the substrate 110, the substrate 110 is mounted on the substrate plate 320 of the vacuum chamber.

After the hole transporting material 340, the electron transporting material 360 and the green phosphorescent dopant (not shown) are arranged in the source 330, the source 330 is heated so that the direction in which the hole transporting materials 340 are arranged .

At this time, since the hole transport material 340 and the electron transport material 360 are spaced apart from each other in the source 330, as shown in the drawing, the region A1 in which only the hole transport material 340 is evaporated, The region A2 where the material 340 and the electron transporting material 360 are simultaneously evaporated and the region A3 where only the electron transporting material 360 is evaporated. Then, the green phosphorescent dopant (not shown) is evaporated simultaneously in all regions.

The scan of the source 330 starts at one side of the substrate 110. That is, the region A1 in which only the hole transporting material 340 is evaporated is located at one side of the substrate 110, and is evaporated to the substrate 110 according to the scan of the source 330 and deposited.

4B, when the source 330 is scanned for the first time, the region A1 to be deposited from the hole transport material 340 is first deposited on the substrate 110, so that only the hole transport material 340 is deposited on the substrate 110 to form a hole transporting layer 132.

A region A2 in which the hole transporting material 340 and the electron transporting material 360 are evaporated at the same time is subsequently deposited on the substrate 110 so that the hole transporting material 340 and the electron transporting material 360 are co- Emitting layer 140 is formed.

A region A3 in which the electron transporting material 360 is evaporated is then deposited on the substrate 110 to form the electron transporting layer 151. [ 4C, a hole transporting layer 132, a light emitting layer 140, and an electron transporting layer 151 are sequentially formed on the substrate 110. In this case, At this time, the scan of the source 330 is terminated at the other side of the substrate 110. That is, as shown in the figure, the scan is completed after the area A3 where only the electron transporting material 360 is evaporated completely goes out to the other side of the substrate 110.

Next, an electron transport layer and a second electrode are formed on the substrate 110 on which the electron transport layer 151 is formed, thereby manufacturing an organic electroluminescent device according to an embodiment of the present invention.

As described above, in the method of manufacturing an organic electroluminescent device according to an embodiment of the present invention, the electron transporting material and the hole transporting material are spaced apart from the source that moves in one direction, so that the hole transporting layer 132, The light emitting layer 140, and the electron transporting layer 151 can be easily formed.

Hereinafter, the organic electroluminescent device of the present invention will be described in detail in the following examples. However, the following examples are illustrative of the present invention, but the present invention is not limited to the following examples.

Example 1

And patterned so as to have a light emitting area of 3 mm x 3 mm on the glass substrate and then cleaned. On the substrate, ITO (anode) was formed to a thickness of 500 Å, and a hole injection layer (CuPc) was formed to a thickness of 1000 Å. Then, the source was provided with NPD as a hole transporting material, the spiro-PBD as an electron transporting material, and Ir (PPY) ₃ as a green phosphorescent dopant. Subsequently, the moving source was scanned with heat to form a hole transporting layer having a thickness of 1000 Å, and a 300 Å thick emission layer in which NPD and spiro-PBD were mixed as a green emitting layer was formed to form a 200 Å thick electron transporting layer . At this time, the doping concentration of the dopant was 18%, and the mixing ratio of NPD and spiro-PBD in the light emitting layer was 1: 1. Next, LiF as an electron injection layer was formed to a thickness of 10 ANGSTROM, and Al as a cathode was formed to a thickness of 1000 ANGSTROM to manufacture an organic electroluminescent device.

Comparative Example

A hole injection layer was formed in the same manner as in Example 1 described above, and CuPc was formed to a thickness of 1000 A as a hole transport layer in a chamber provided with one source. Then, Ir (PPY) ₃ , which is a dopant, was doped into NPD as a host to form a light emitting layer with a thickness of 300 Å at a doping concentration of 18%. Next, an electron transport layer spiro-PBD was formed to a thickness of 200 ANGSTROM, an electron injection layer LiF was formed to a thickness of 10 ANGSTROM, and an anode Al was formed to a thickness of 1000 ANGSTROM to prepare an organic electroluminescent device.

The driving voltage, the luminous efficiency, the quantum efficiency, and the color coordinates of the organic electroluminescent device manufactured according to Example 1 and Comparative Example were measured and shown in Table 1 below, and a graph of the lifetime was shown in FIG.

Driving voltage
(V) Luminous efficiency
(Cd / A) Color coordinates Quantum efficiency (%)
CIE_x CIE_y Comparative Example 3.6 51.8 0.236 0.718 13.9 Example 1 3.8 76.3 0.248 0.706 20.6

Referring to Table 1 and FIG. 5, it can be seen that the luminous efficiency and the quantum efficiency are improved about 1.5 times as compared to the comparative example in the first embodiment of the present invention. That is, compared with an organic electroluminescent device in which one dopant is contained in one host, which is a comparative example, Embodiment 1 of the present invention uses a source provided with two hosts to emit a light emitting layer, which is a mixture of a hole transporting material and an electron transporting material It was found that the luminous efficiency and the quantum efficiency can be increased.

Example 2

An organic electroluminescent device was manufactured by changing the mixing ratio of the hole transporting material and the electron transporting material to 2: 1 under the same process conditions as those in Example 1 described above.

Example 3

An organic electroluminescent device was manufactured by changing the mixing ratio of the hole transporting material and the electron transporting material to 1: 2 under the same process conditions as those of the above-described Example 1.

FIG. 6 is a graph showing a lifetime of the organic electroluminescent device manufactured according to Examples 1, 2, and 3.

Referring to FIG. 6, it can be seen that the lifetime characteristics of the organic electroluminescent device manufactured according to Example 1 are significantly improved as compared with the organic electroluminescent device manufactured according to Examples 2 and 3.

That is, as in Embodiment 1 of the present invention, by forming the mixture ratio of the hole transporting material and the electron transporting material serving as the host at 1: 1, the charges in the light emitting layer are biased to either side, It is advantageous in that it can be prevented from being promoted.

As described above, the organic electroluminescent device according to one embodiment of the present invention is advantageous in that the luminescent efficiency and lifetime can be greatly improved by forming the luminescent layer having a mixing ratio of the hole transporting material and the electron transporting material of 1: 1.

Further, there is an advantage that a hole transporting layer, a light emitting layer and an electron transporting layer can be easily formed through a process of scanning a source.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (7)

Forming a first electrode on the substrate;
Preparing a source in which a hole transporting material and an electron transporting material are arranged in order on the substrate on which the first electrode is formed;
Sequentially scanning a hole transporting layer, a light emitting layer, which is a mixed layer of the hole transporting material and the electron transporting material, and an electron transporting layer, simultaneously on the first electrode while heating the source in a direction in which the hole transporting material is disposed, ; And
And forming a second electrode on the light emitting layer,
The step of forming the hole transporting layer, the light emitting layer and the electron transporting layer, which are a mixed layer of the hole transporting material and the electron transporting material,
Depositing a hole transport material of the source first on the substrate to form a hole transport layer;
The deposition of the electron transporting material of the source is started while the hole transporting layer is formed and the light emitting layer is formed by coevaporation of the hole transporting material and the electron transporting material; And
And forming an electron transport layer by depositing only the electron transporting material while the light emitting layer is formed.
The method according to claim 1,
Wherein the source further comprises a green phosphorescent dopant material positioned between the hole transport material and the electron transport material,
And depositing the dopant material simultaneously with the deposition of the hole transporting material and the electron transporting material.
delete The method according to claim 1,
Before forming the hole transporting layer,
And forming a hole injection layer on the first electrode.
The method according to claim 1,
Before forming the second electrode,
And forming an electron injection layer on the electron transport layer.
The method according to claim 1,
Wherein the light emitting layer has a mixing ratio of the hole transporting material and the electron transporting material is 1: 1.
The method according to claim 1,
Wherein the scanning of the source starts at one side of the substrate and ends at the other side of the substrate.

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