KR100971348B1 - Organic Electroluminescent Device - Google Patents

Abstract

The present invention relates to an organic electroluminescent device (hereinafter referred to as "organic EL device"), and more particularly to an organic electroluminescent device an insulating layer, and the like, thereby improving the hole injecting ability and the electron injecting ability and increasing the light emitting efficiency.

Description

[0001] The present invention relates to an organic electroluminescent device,

1 is a schematic view for explaining a basic structure of a general organic EL element.

2 is a schematic view for explaining a configuration of an organic EL device including an ion insulator film of the present invention.

3 is a view illustrating a process of injecting a hole between a positive electrode and a hole injection layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

10, 20: substrate 11, 21: positive electrode

13, 23: Hole injection layer 15, 25: Hole transport layer

17, 27: organic light emitting layer 18, 28: electron injecting layer / electron transporting layer

19, 29: second ion insulator film 22: first ion insulator film

111, 121: negative polarity

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device (hereinafter referred to as "organic EL device"), and more particularly to an organic electroluminescent device having an ionic insulating layer ), Thereby improving the hole injecting ability and the electron injecting ability and increasing the light emitting efficiency.

The organic electroluminescent device refers to an optoelectronic device that causes light reflection in response to a residual through the device. The organic electroluminescent device included in the electroluminescent device is usually an organic light emitting diode (OLED) Quot;).

In general, an organic EL device includes a transparent anode layer, an organic light emitting layer, and a metal cathode layer sequentially formed on a glass substrate on a substrate, and then a voltage is applied between the anode and the cathode The principle of self-luminescence in which light is generated in the process of energy transfer to the ground state after the recombination of electrons and holes injected from the main surface is recombined, is used again. It is light in weight, and has a very good luminance, and is attracting attention as a next generation display.

The basic structure of a general organic EL device will be described in detail with reference to the accompanying schematic drawings.

1, an anode 11, a hole injection layer 13, and a hole transporting layer 15 are sequentially formed on a transparent substrate 10 made of a transparent material such as quartz .

At this time, the positive electrode 11 is made of indium tin oxide (ITO) and indium zinc oxide (IZO), which have a large work function and are easy to inject holes and have a transparent characteristic in a visible light range And is formed using a metal oxide film.

The Hole Injection Layer 13 is a layer of CoO 2 having a work function of ITO and a highest occupied molecular orbital (HOMO) Copper phthalocyanine (CuPC) or a phenylamine compound such as 4,4,4-tri (3-methylphenyl-phenylamino) triphenylamine (4,4 ' methylphenyl-phenylamino) -triphenylamine (m-MTDATA).

The hole transport layer 15 is formed of a material such as? -NPD or N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'- , 4'-diamine (N, N'-dipheny-N, N'-bis (3-methyl phenyl) -1,1'-diphenyl-4,4'-diamine; TPD).

And an organic light emitting layer 17 is formed on the hole transport layer 15.

In the organic light emitting layer 17, holes are moved from the positive electrode and electrons are injected from the negative electrode to form an exciton. At this time, the intrinsic wavelength of the organic material applied to the light emitting layer and the composition ratio of the host and the dopant To emit light of various specific wavelengths from the exciton.

4-dicyanomethylene-6-cp-julolidinostyryl-2-tert-butyl-4H-pyran (DCJTB) is used as the organic emission layer forming material, (Phenylene vinylene) (PPV) and aluminum tris (8-hydroxyquinoline; Alq ₃ ) are used for blue, and PPP, PF, PFV and Spiro-PF spiro-PF) or the like.

An electron transporting layer and an electron injection layer 18 are sequentially formed on the organic light emitting layer. In this case, the electron transport layer and the light emitting efficiency are improved and the interface characteristics between the cathode and the electron injection layer are improved A second ion insulator film 19, which is a buffer layer, may be formed on the electron injection layer.

The electron transport layer uses 1,2,3-triazole or aluminum quinolinol as an electron transporting material for smoothly transporting electrons supplied from a negative electrode.

The second ionic insulating film may be formed using a compound of Group I-VI of the periodic table, preferably lithium fluoride (LiF), which flattens the uneven surface of the negative electrode to make the adhesive force to the luminescent layer And it also plays an important role in improving the performance of the organic EL device by preventing carrier trap due to coupling caused by direct bonding between the organic material and the negative electrode metal.

A metal cathode (111) is formed on the ion insulator film (19).

The negative electrode is formed using a metal having a low work function, for example, magnesium (Mg) or calcium (Ca), or a metal having a high work function but being stable during the process and easy to deposit, such as aluminum .                         

As described above, in order to improve the efficiency of the organic EL device, researches on each layer constituting the device are still underway. Until now, the electron mobility of the electron injection layer / transport layer is relatively lower than that of the hole injection layer / transport layer More attention has been focused on the development of materials for electron injection / transport layers and improvement directions that can be considered to improve the electron transfer capability.

However, it is known that when the hole injecting and transporting ability is improved, trapped positive (+) ions are formed inside the device and the electron injecting ability is further improved, and a need for a material capable of improving the hole injecting ability .

It is an object of the present invention to provide an organic EL device improved in luminous efficiency of an organic EL device by using an ion insulator film of an electron injection layer as a buffer layer of a hole injection layer while studying to solve the above simple problem .

It is another object of the present invention to provide a method of manufacturing the organic EL device.

In order to achieve the above object, the present invention provides an organic EL device including a buffer layer used between the positive electrode and the hole injection layer for improving electron injection capability.

Hereinafter, the present invention will be described in detail.

In the present invention, a positive electrode, a first ion insulator film, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, a second ion insulator film as a buffer layer for transferring electrons, And a cathode electrode are sequentially formed.

At this time, the first ion-insulating layer is a lithium fluoride (LiF), lithium oxide (Li ₂ O), sodium chloride (NaCl), magnesium fluoride (MgF _2), fluoride calcium flow (CaF _2), strontium fluoride (SrF ₂ ) And barium fluoride (BaF ₂ ), preferably LiF.

The thickness of the first ionic insulation layer is 0.1 to 50 Å, preferably 1 to 10 Å.

The first ion insulator film is preferably formed on the positive electrode by electron beam evaporation.

In the present invention,

Forming a positive electrode on the organic substrate;

Forming a first ion insulator film on the positive electrode;

Sequentially forming a hole injecting layer and a hole transporting layer on the first ion insulator film;

Forming an organic light emitting layer on the hole transport layer;

Sequentially forming an electron transport layer and an electron injection layer on the organic light emitting layer;

Forming a second ion insulator film on the electron injection layer; And                     

And forming a negative electrode on the second ion insulator film.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, and is a schematic view for explaining the structure of an organic EL device.

Referring to FIG. 2, a positive electrode 21 is formed on a substrate 20, and a first ionic insulation film 22 is formed thereon.

At this time, it is preferable that the positive electrode is formed using a metal oxide film such as ITO and IZO, and the first ion insulator film is formed to a thickness of 1 ANGSTROM to 10 ANGSTROM by electron beam evaporation using LiF.

A hole injecting layer 23 and a hole transporting layer 25 are sequentially formed on the first ion insulator film 22.

Thereafter, an organic light emitting layer 27 is formed on the hole transporting layer 25, and then an electron transporting layer / electron injecting layer 28 is sequentially formed thereon.

A second ion insulator film 29 is formed on the electron transport layer / electron injection layer 28.

The second ionic insulating film is preferably formed using lithium fluoride.

And a negative electrode 121 is formed on the second ion insulator film.

At this time, the cathode, the hole injecting layer / the hole transporting layer, the light emitting layer, and the electron transporting layer constituting the organic EL device of the present invention are formed using common ones.

When an ion insulator film is formed between the ITO layer and the hole injection layer, the energy barrier between the ITO layer and the hole injection layer is reduced, resulting in a larger electron injection effect. That is, in the organic EL device, the hole injection process in the ITO layer as a positive electrode is performed beyond the energy barrier. When an ion insulating film is formed between the ITO layer and the hole injection layer, hole transfer from the ITO layer to the hole injection layer results in And is improved by the tunneling effect (see FIG. 3). As a result, the amount of trapped holes in the device increases, and a field is formed in the device to attract electrons. Therefore, the electron injection capability is improved as well as the hole injection capability, .

As described above, the enhancement of the hole injecting ability of the organic EL element improves the luminous efficiency of the element, which enables the power consumption at the time of driving the panel to be shortened, so that the lifetime of the element is also increased by driving at low power consumption .

As described above, the organic EL device of the present invention reduces the difference in energy barrier by forming an ion insulator film between the positive electrode and the hole injection layer, thereby improving the hole injecting ability and electron injecting ability, Efficiency can be improved.

Claims (3)

A first ionic insulating film, a hole injecting layer, a hole transporting layer, an organic light emitting layer, an electron transporting layer, an electron injecting layer, a second ion insulator film as a buffer layer for transferring electrons, and a negative electrode are successively formed on the transparent substrate, And an organic EL layer formed on the organic EL layer. The method according to claim 1, The first ion insulating layer is a lithium fluoride (LiF), lithium oxide (Li ₂ O), sodium chloride (NaCl), magnesium fluoride (MgF _2), fluoride calcium flow (CaF _2), strontium fluoride (SrF _2), and And barium fluoride (BaF ₂ ). The method according to claim 1, Wherein the thickness of the first ion insulator film is 0.1 to 50 ANGSTROM.

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