KR100534578B1 - Electroluminescence display device comprising binder in emitting layer - Google Patents

Abstract

The present invention relates to a low molecular weight organic electroluminescent device, comprising: a substrate, an anode electrode, a light emitting layer, and a cathode electrode, wherein the light emitting layer comprises a mixture of a light emitting host material, a light emitting dopant, and a binder. By providing the organic electroluminescent device, it is possible to ensure the stability of the deposited film not only on the substrate that is not bent but also on the substrate that is bent, and to provide a low molecular organic electroluminescent device that does not rupture or crack when the film is bent.

Description

A low molecular weight organic electroluminescent device comprising a binder in a light emitting layer {ELECTROLUMINESCENCE DISPLAY DEVICE COMPRISING BINDER IN EMITTING LAYER}

[Industrial use]

The present invention relates to a low molecular weight organic electroluminescent device, and more particularly, to a low molecular weight organic electroluminescent device capable of ensuring stability of a deposited film on a curved substrate as well as a non-flexible substrate.

[Prior art]

In general, the organic EL device is composed of various layers such as an anode and a cathode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer. The organic EL device is divided into polymer and low molecule according to the material used. In the case of the low molecular organic EL device, each layer is introduced by vacuum deposition, and in the case of the polymer organic EL device, light emission is performed using a spin coating process. You can make a device.

In particular, in the case of a low molecular weight organic EL device, since the vapor deposition process is used, the organic EL device is fabricated by vapor deposition on a non-flexible substrate such as a glass substrate.

FIG. 1 illustrates a case where a process such as vacuum deposition of a light emitting layer for an organic EL device is deposited on a flexible substrate, and the curved portion of the substrate 10, the light emitting host material 21, and the light emitting dopant ( Since the part 22 is not in close contact between the co-deposited light emitting layers 20, there is a problem that it is difficult to manufacture a low molecular organic electroluminescent device using a curved substrate because the film is broken or cracked when the substrate is bent due to lack of deposition stability. there was.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems described above, and an object of the present invention is to provide a low molecular organic electroluminescent device capable of stably forming a light emitting layer on a flexible substrate.

The present invention to achieve the above object,

In the low molecular organic electroluminescent device comprising a substrate, a first electrode, a light emitting layer and a second electrode,

The light emitting layer provides a low molecular weight organic electroluminescent device comprising a mixture of a light emitting host material, a light emitting dopant and a binder.

Hereinafter, the present invention will be described in more detail.

2 is a cross-sectional view illustrating a schematic cross-sectional view of a low molecular weight organic electroluminescent device having a light emitting layer formed on a flexible substrate according to an embodiment of the present invention.

The low molecular weight organic electroluminescent device of the present invention includes a substrate 30, a first electrode (not shown), a light emitting layer 40 and a second electrode (not shown), and in the case of the light emitting layer 40, a light emitting host material 41 ), A mixture of the light emitting dopant 42 and the binder 43.

The substrate may be a non-flexible conventional substrate such as a flexible substrate and a glass substrate. Flexible substrates include polycarbonate, polyethyleneterephthalate, polyestersulfonate, polysulfonate, polyarylate, fluorinated polyimide, transparent fluorine resin, Organic and organic EL substrates that cannot pass oxygen and moisture by laminating inorganic materials and organic materials on plastic substrates such as transparent acrylic resins can be used.

A conventional first electrode material is deposited on this substrate. In the case of the top emission structure, the transparent electrode may be used as the first electrode material, and in the case of the bottom emission structure, the metal electrode may be used.

As such, the light emitting layer is deposited over the entire surface of the substrate on which the first electrode material is deposited.

In general, in the case of a low molecular organic EL device, the light emitting layer deposits a mixed material composed of a light emitting host material and a light emitting dopant material by a vacuum deposition method or a spin coating method. Three substances are mixed and used in a three component system.

As the light emitting host material, a material capable of transporting charge (hole or electron) and transferring energy to the light emitting dopant is used.

The carbazole type, the arylamine type, the hydrazone type, the stilbene type, the starburst type oxadiazole type, etc. are preferable. Low molecules with charge transport capability are preferred.

In addition, a phosphorescent dopant is used as the light emitting dopant. The phosphorescent dopant is a metal organometallic complex selected from the group consisting of Ir, Pt, Eu, and Tb, which uses a material capable of phosphorescent emission in a triplet state. It is preferable.

Meanwhile, in the present invention, a binder is used to form a stable film in the light emitting layer even on a substrate that is not bent and a substrate that can be bent.

The binder material is a polymer capable of depositing or using a material capable of providing stability of the film as a low molecule having excellent film properties.

Preferably, polymers capable of polymerizing low molecules such as carbazole-based, arylamine-based, hydrazone-based, stilbene-based, starburst-based, and oxadiazole-based polymers with a molecular weight of 5000 or less, and carbazole-based, arylamine-based, and hydrazone-based systems Low molecular oligomers or dendrimers, such as stilbene, starburst, and oxadiazole, may be used, and the amount of the binder material is 75% or less by mass fraction.

In the case of using the polymer that can be deposited as the binder material, a deposition process may be used as a light emitting layer forming method, and in the case of using low molecular weight having excellent film properties, laser thermal transfer (LITI) may be applied.

Then, a second electrode is deposited on the light emitting layer and encapsulated with a metal can to manufacture a low molecular organic electroluminescent device. As the second electrode, a metal electrode is used when the first electrode is a transparent electrode, and a transparent electrode is used when the first electrode is a metal electrode.

As described above, the low molecular weight organic electroluminescent device manufactured in the present invention can provide a stable low molecular weight organic electroluminescent device because the film stability is excellent not only in the flexible substrate but also in the flexible substrate by using the binder in the light emitting layer.

1 is a schematic view showing a state in which a light emitting layer is formed on a substrate in the case of a low molecular organic electroluminescent device using a flexible substrate.

2 is a schematic diagram showing a state in which a light emitting layer is formed on a flexible substrate manufactured according to an embodiment of the present invention.

Claims (11)

In the low molecular organic electroluminescent device comprising a substrate, a first electrode, an organic light emitting layer and a second electrode, Wherein the organic light emitting layer comprises a mixture of an organic light emitting host material, an organic light emitting dopant, and an organic binder. The method of claim 1, And the organic light emitting host material is a material capable of transferring energy to the organic light emitting dopant. The method of claim 2, The organic light emitting host material is one selected from the group consisting of carbazole, arylamine, hydrazone, stilbene, starburst, and oxadiazoles A low molecular organic electroluminescent device which is a low molecule having a charge transport ability. The method of claim 1, The organic light emitting device is a low molecular weight organic electroluminescent device is a phosphorescent dopant. The method of claim 4, wherein Wherein said organic phosphorescent dopant is one organic metal complex selected from the group consisting of Ir, Pt, Eu, and Tb. The method of claim 1, The organic binder is a low molecular organic electroluminescent device which is a low molecular having a polymer or film property that can be deposited. The method of claim 6, The organic binder is a vaporizable polymer or carbazole-based polymer prepared by polymerizing at least one low molecule selected from the group consisting of carbazole-based, arylamine-based, hydrazone-based, stilbene-based, starburst-based, and oxadiazole-based compounds with a molecular weight of 5000 or less. A low molecular weight organic electroluminescent device which is a low molecular oligomer or dendrimer selected from the group consisting of arylamines, hydrazones, stilbenes, starbursts, and oxadiazoles. The method of claim 1, The substrate is a low molecular organic electroluminescent device which is a substrate made of a flexible material. The method of claim 8, Substrate made of the flexible material is a polycarbonate, polyethyleneterephthalate, polyestersulfonate, polysulfonate, polyarylate, fluorinated polyimide, transparent A low molecular weight organic electroluminescent device which is a substrate which does not pass oxygen and moisture by laminating inorganic and organic materials on one kind of plastic substrate selected from the group consisting of fluorocarbon resin and transparent acrylic resin. The method of claim 6, When the organic binder is a low molecular weight having a film property, the light emitting layer is a low molecular organic electroluminescent device is formed by the laser induced thermal imaging (LITI). The method of claim 6, When the organic binder is a polymer capable of depositing the light emitting layer is a low molecular organic electroluminescent device is formed by vacuum deposition or spin coating method.