KR100721952B1 - Organic light emitting device and method of fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display having improved luminous efficiency and device life, and to a method of manufacturing the organic electroluminescent display, comprising: a first electrode formed on an insulating substrate; A hole injection layer formed on the first electrode; A first hole transport layer formed on the hole injection layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; A second hole transport layer formed on the first hole transport layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; The light emitting layer formed on the hole transport layer; An electron injection layer formed on the light emitting layer; And a second electrode formed on the electron injection layer.

Organic Electroluminescent Display, Multilayer Hole Transport Layer

Description

Organic Light Emitting Device and Method of Fabrication thereof

1 is a schematic cross-sectional view for describing a conventional organic light emitting display device.

2 is a schematic cross-sectional view illustrating an organic light emitting display device according to an embodiment of the present invention.

3 and 4 are diagrams for describing current efficiency and device life according to the configuration of the organic light emitting display device.

(Explanation of symbols for main parts of drawing)

200; Insulating substrate 210; First electrode

220; Hole injection layer 230; Hole transport layer

231; A first hole transport layer 233; 2nd hole transport layer

240; Light emitting layer 250; Electron injection layer

260; Upper electrode

The present invention relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, to an organic light emitting display device and a method of manufacturing the light emitting efficiency and device life is improved by forming a hole injection layer in the form of a laminated film. .

In general, an organic light emitting display device, which is one of flat panel displays, injects electrons and holes into an emission layer from an electron injection electrode and a hole injection electrode, respectively. The light emitting display device emits light when an exciton in which injected electrons and holes are combined falls from an excited state to a ground state.

Due to this principle, unlike a conventional thin film liquid crystal display device, since a separate light source is not required, there is an advantage of reducing the volume and weight of the device.

In addition, the organic light emitting display device may be divided into a passive matrix type and an active matrix type according to a driving method.

The passive matrix type organic light emitting display device has a simple structure and a simple manufacturing method. However, the passive matrix type organic light emitting display device has a high power consumption and a large area of the display device, and the opening ratio decreases as the number of wirings increases.

Therefore, the pass matrix organic electroluminescent display device is used when applied to a small display element, whereas the active matrix organic electroluminescent display device is used when applied to a large area display device.

Hereinafter, a conventional organic light emitting display device will be described with reference to the accompanying drawings.

1 is a schematic cross-sectional view for describing a conventional organic light emitting display device.

Referring to FIG. 1, a conventional organic light emitting display device includes a first electrode 110 and a second electrode 160 on an insulating substrate 100, and between the first electrode 110 and the second electrode 160. It consists of an organic film formed in the. In this case, the organic layer has a structure in which a hole injection layer 120 (HIL), a hole transport layer 130 (HTL), a light emitting layer 140 (EML), and an electron injection layer 150 (ETL) are stacked.

In the conventional organic light emitting display device, any one of the first electrode 110 and the second electrode 160, for example, a current, may be formed through the first electrode 110 and the second electrode 160. And a hole through the first electrode 110 serving as the anode electrode, and a second electrode 160 serving as another one of the first electrode 110 and the second electrode 160, for example, a cathode electrode. When electrons are flowed through, the holes and the electrons are combined in the emission layer 140 and the EML, thereby emitting light.

On the other hand, in the conventional organic light emitting display device as described above, the luminous efficiency and lifespan are determined by each layer constituting the organic layer.

Therefore, in recent years, various studies have been conducted to improve the light emission efficiency and lifespan of the organic light emitting display device.

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic electroluminescent display device and a method of manufacturing the same, in which the hole injection layer is formed in the form of a laminated film, thereby improving light emission efficiency and device life.

An organic electroluminescent display device of the present invention for achieving the above object is a first electrode formed on an insulating substrate; A hole injection layer formed on the first electrode; A first hole transport layer formed on the hole injection layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; A second hole transport layer formed on the first hole transport layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; The light emitting layer formed on the hole transport layer; An electron injection layer formed on the light emitting layer; And a second electrode formed on the electron injection layer.

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Preferably, the homo level values of the hole injection layer, the first hole transport layer, the second hole transport layer, and the light emitting layer are sequentially.

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The hole transport layer preferably has a total thickness of 100 kPa to 1000 kPa.

In addition, the manufacturing method of the organic light emitting display device of the present invention comprises the steps of: forming a hole injection layer on the first electrode formed on the insulating substrate; Forming a first hole transport layer made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group on the hole injection layer, and corresponding to the HOMO level values of the hole injection layer and the light emitting layer; Forming a second hole transport layer formed of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group on the first hole transport layer and between a hole injection layer and a HOMO level value of the light emitting layer; Forming the light emitting layer on the second hole transport layer; Forming an electron injection layer on the light emitting layer; And forming a second electrode on the electron injection layer.

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The hole transport layer is any one selected from among spin-coating, cast, ink-jet, dipping metjod, and printing methods. After carrying out the wet process, it is preferable to form through any one of thermosetting, UV curing, and a combination thereof.

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

2 is a schematic cross-sectional view for describing an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 2, an organic light emitting display device according to an exemplary embodiment of the present invention includes a first electrode 210 and a second electrode 260 formed on an insulating substrate 200, and the first electrode 210. And an organic film formed between the second electrodes 260.

In this case, the organic layer is formed on the hole injection layer 220, HIL, and hole injection layer 220 formed on the first electrode 210, and is formed at least on the first hole transport layer 231, HTL, and hole. And a second hole transport layer 233 (HTL) and a hole transport layer 230 (HTL) having a multilayer structure, and a light emitting layer formed on the hole transport layer 230 and emitting light through a combination of electrons and holes ( 240, EML, and an electron transport layer (ETL) formed on the light emitting layer.

In addition, whether or not the TFT is included in the insulating substrate 200 depends on the driving mode of the organic light emitting display device. That is, the insulating substrate 200 includes a TFT when the organic light emitting display device is driven in an active matrix type, and in this case, any one of the first electrode 210 and the second electrode 260 may be used. For example, it is obvious that the first electrode 210 serving as the anode electrode is electrically connected to the TFT.

In addition, the insulating substrate 200 does not include a TFT when the organic light emitting display device is driven in a passive matrix type, and the first electrode 210 and the second electrode 260 are directly connected to an external circuit module. Can be electrically connected.

Hereinafter, the organic electroluminescent display according to the exemplary embodiment of the present invention will be described in detail.

First, the first electrode 210 is formed on the insulating substrate 200. In this case, the first electrode 210 serves as a pixel electrode defining a pixel region of the organic light emitting display, and also acts as an anode electrode or a cathode electrode depending on whether holes or electrons are injected. In the present invention, the first electrode 210 acts as an anode, for example.

After forming the first electrode 210, a hole injection layer 220 is formed on the first electrode 210. In this case, the hole injection layer 220 may be made of any one conductive polymer selected from a thiophene-based material such as PEDOT, an aniline-based material such as PANI, a pyrrole-based material such as PPy, and a mixture thereof. It is not intended to limit the material.

In addition, the hole injection layer 220 is metal nanoparticles (nano particles), metal nanowires (nano wire), inorganic conductive nanoparticles, inorganic conductive nanowires, C60, C70 and carbon nanotubes (CNT) in the polymer material It may be made by containing any one of the nanostructures selected.

In addition, the hole injection layer 220 may contain any one selected from Na, Li, K, As, and Sb in the polymer material.

In addition, the hole injection layer 220 may be made of any one of a low molecular material selected from CuPc, TNATA, TCTA and TDAPB. When the hole injection layer 220 is made of a low molecular material, it is formed through a deposition process.

After the hole injection layer 220 is formed, a first hole transport layer 231 is formed on the hole injection layer 220, and a second hole transport layer 233 is formed on the first hole transport layer 231. The hole transport layer 230 including the first hole transport layer 231 and the second hole transport layer 233 is formed.

In this case, the homo level value of the material constituting the first hole transport layer 231 and the second hole transport layer 233 may correspond to a homo level value between the hole injection layer 220 and the light emitting layer 240. The homo level values of the first hole transport layer 231 and the second hole transport layer 233 are preferably sequentially. For example, the first hole transport layer 231 and the second hole transport layer 233 are soluble in an organic solvent, and may be made of an oligomer or a polymer material having a hole transport group.

In addition, the hole transport layer 230 is selected from a spin-coating method, a cast method, an ink-jet method, a dipping metjod, and a printing method. After performing the wet process (wet process) of any one method, it is formed through the thermosetting, UV curing and their composite process, the total thickness is preferably 100 ~ 1000Å.

After the hole transport layer 230 is formed, an emission layer 240 that emits light by combining electrons and holes is formed on the hole transport layer 230.

At this time, the light emitting layer 240 is a material that varies depending on the color of the light emitted from the light emitting layer 240. For example, when the light emitting layer 240 emits red light, Alq3 (host) / DCJTB (fluorescent dopant), Alq3 (host) / DCM (fluorescent dopant), CBP (host) / PtOEP (phosphorescent organometallic complex) It may be made of a low molecular material such as) and a polymer material such as PFO-based polymer, PPV-based polymer.

In addition, when the light emitting layer 240 emits green light, low-molecular materials such as Alq3, Alq3 (host) / C545t (dopant), CBP (host) / IrPPy (phosphorus organometallic complex), PFO-based polymer, and PPV-based polymer It may be made of a polymer material such as.

In addition, when the light emitting layer 240 emits blue light, low-molecular materials such as DPVBi, Spiro-DPVBi, Spiro-6P, Distylbenze (DSB) and Distyrylarylene (DSA), PFO-based polymers, PPV-based polymers, etc. It may be made of a polymer material.

After forming the emission layer 240, an electron injection layer 250 is formed on the emission layer 240. In this case, the electron injection layer 250 may be made of any one selected from Al, Ga, Zn and Be-based organic compounds, oxadiazole, triazole, benzimidazole and quinoxaline-based organic compounds, oxadiazole-based polymer materials, and equivalents thereof.

After forming the electron injection layer 250, a second electrode 260 is formed on the electron injection layer 250. In this case, since the first electrode 210 acts as an anode electrode, the second electrode 260 acts as a cathode electrode.

Thereafter, the organic electroluminescent display device of the present invention is manufactured by performing a manufacturing process of a general organic electroluminescent display device such as a bag.

3 and 4 are diagrams for describing current efficiency and device life according to the configuration of the organic light emitting display device.

The element configurations of A, B, C, and D shown in FIGS. 3 and 4 are shown in Table 1, respectively.

A B C D First electrode ITO ITO ITO ITO Hole injection layer PEDOT: PSS (80nm) PEDOT: PSS (80nm) PEDOT: PSS (80nm) PEDOT: PSS (80nm) 1st hole transport layer none HTL-1 Polymer (30nm) none HTL-1 Polymer (15nm) 2nd hole transport layer none none HTL-2 Polymer (30nm) HTL-2 Polymer (15nm) Light emitting layer Fluorene-based blue light emitting polymer (60nm) Fluorene-based blue light emitting polymer (60nm) Fluorene-based blue light emitting polymer (60nm) Fluorene-based blue light emitting polymer (60nm) Electron transport layer LiF (1.5 nm) LiF (1.5 nm) LiF (1.5 nm) LiF (1.5 nm) Second electrode Mg-Ag (10: 1, 50 nm) Mg-Ag (10: 1, 50 nm) Mg-Ag (10: 1, 50 nm) Mg-Ag (10: 1, 50 nm)

In Table 1, the HTL-1 polymer is a fluorene-alt-bis-N, N'-phenyl-1,4-phenylenediamine-based alternating polymer, and the HTL-2 polymer is a fluorene-alt-triphenylamine-based alternating polymer. In addition, HOMO level shows the value of PEDOT: PSS, 5.1-5.2 eV, HTL-1, 5.26 eV, HTL-2, 5.45 eV, fluorene type blue light emitting polymer, and 5.64 eV.

In addition, each of the A, B, C and D elements is formed as follows.

First, the insulating substrate on which ITO is formed is sequentially cleaned by ultrapure water cleaning, organic cleaning, UV / ozone cleaning, and dried at 190 ° C. for 10 minutes after PEDOT: PSS spin coating on the ITO. Then, after spin coating the HTL-1 and HTL-2 on the PEDOT: PSS, and dried for 10 minutes at 250 ℃, the blue light emitting polymer is deposited at 150 ℃, nitrogen atmosphere, and dried for 20 minutes. After the blue light-emitting polymer is formed, LiF and Mg-Ag are thermally deposited in a deposition apparatus to form a film. Finally, each of the elements A, B, C and D is sealed in a nitrogen atmosphere.

Referring to FIGS. 3 and 4 where the current efficiency and device life of each of the A, B, C, and D devices as described above are shown, it can be seen that the D device has the best current efficiency and device life.

That is, the first electrode as compared to the device consisting of the first electrode / hole injection layer / light emitting layer / electron injection layer / second electrode, or the first electrode / hole injection layer / single electron transport layer / light emitting layer / electron injection layer / second electrode It can be seen that the current efficiency and device life of the structure consisting of / hole injection layer / multiple electron transport layer / light emitting layer / electron injection layer / second electrode are excellent.

As described above, in the organic light emitting display device of the present invention, since the hole injection layer has a multilayer structure, the light emission efficiency and lifespan are improved.

According to the present invention as described above, the present invention can provide an organic electroluminescent display device and a method of manufacturing the same by improving the light emitting efficiency and device life by forming a hole injection layer in the form of a laminated film.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (9)

A first electrode formed on the insulating substrate; A hole injection layer formed on the first electrode; A first hole transport layer formed on the hole injection layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; A second hole transport layer formed on the first hole transport layer and made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; The light emitting layer formed on the hole transport layer; An electron injection layer formed on the light emitting layer; And And a second electrode formed on the electron injection layer. delete delete The method of claim 3, wherein And the homo level values of the hole injection layer, the first hole transport layer, the second hole transport layer, and the light emitting layer are sequential. delete The method of claim 1, And the total thickness of the hole transport layer is 100 kW to 1000 kW. Forming a hole injection layer on the first electrode formed on the insulating substrate; Forming a first hole transport layer made of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group on the hole injection layer, and corresponding to the HOMO level values of the hole injection layer and the light emitting layer; Forming a second hole transport layer formed of an oligomer or a polymer material soluble in an organic solvent and having a hole transport group on the first hole transport layer, and corresponding to a HOMO level value of the hole injection layer and the light emitting layer; Forming the light emitting layer on the second hole transport layer; Forming an electron injection layer on the light emitting layer; And And forming a second electrode on the electron injection layer. delete The method of claim 7, wherein The hole transport layer is any one selected from among spin-coating, cast, ink-jet, dipping metjod, and printing methods. After performing a wet process (wet process), the method of manufacturing an organic electroluminescent display device, characterized in that formed through any one of thermosetting, UV curing and a combination thereof.

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