JPH09194832A - Organic led element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat resistance by incorporating a specified polyazomethine into a hole injection transfer layer or a luminescent layer. SOLUTION: A transparent anode 2 is formed by, e.g. vacuum deposition or sputtering on a transparent base plate 1. A hole injection transfer layer 3 containing a polyazomethine of formula I (wherein R1 and R2 are each a group of any one of formulas II to XVII, (m) is 1 to 9, and A is H, CH3 or a group of formula XVIII), a luminescent layer 4, an electron injection transfer layer 5 comprising, e.g. an oxadiazole derivative or diphenoquinone derivative, and a cathode 6 are formed on the anode 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is also called injection electroluminescence (EL) and is an organic thin film EL.
The present invention relates to an organic LED element that emits light by injecting electrons and holes into a substance and recombining them.

[0002]

2. Description of the Related Art FIGS. 10 and 11 show examples of the structure of an organic LED element. First, the organic LE shown in FIG.
In the D element 90, the substrate 91, the anode 92, the hole injecting and transporting layer 93, the light emitting layer 94, the electron injecting and transporting layer 95, and the cathode 9
Each layer is laminated in the order of 6.

When forming the organic LED element 90, first, ITO, which is a transparent electrode, is formed as a positive electrode 92 on a substrate 91 made of a transparent material such as glass by vapor deposition, sputtering, or the like, and N, N is formed on the positive electrode 92. N'-diphenyl-N, N'-bis (3-methylphenyl) -1,
1'-biphenyl-4,4'-diamine (hereinafter TPD
Is referred to as a hole injecting and transporting layer 93.

Then, 1 is formed on the hole injecting and transporting layer 93.
-[4-N, N-bis (p-methoxyphenyl) aminostyryl] naphthalene is formed as a light emitting layer 94, and 2- (4-biphenylyl) -5- (4
-T-Butylphenyl) -1,3,4-oxadiazole is formed as an electron injecting and transporting layer 95, and finally Mg and A
An alloy with g is deposited as a cathode 96 to form a film.

In the organic LED element 80 shown in FIG. 11, the substrate 81, the anode 82, the hole injecting and transporting layer 83,
The light emitting layer 84 and the cathode 85,
On the anode 82 formed on the substrate 81 in the same manner as described above,
An aromatic tertiary amine such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane is deposited as the hole injecting and transporting layer 83 by vapor deposition.

Next, an organic phosphor such as tris (8-quinolinol) aluminum is formed as a light emitting layer 84 on the hole injecting and transporting layer 83, and a metal similar to the above is formed on the light emitting layer 84. , Alloy, metal compound cathode 8
5 is formed by vapor deposition or the like.

[0007]

However, the compound such as TPD used in the conventional organic LED device of this type recrystallizes with the passage of time, and pinholes or short circuits are generated in the LED device. There was a problem that caused it. This is because the melting points of these compounds are low, and thermal deterioration progresses due to heat of processing during device fabrication and heat generated during device driving.

From the viewpoint of production, for example, it is preferable from the viewpoint of cost and productivity that the light emitting layer and the like be formed into a film by spin coating with dilution in a solvent. In the hole injecting and transporting layers 93 and 83, the light emitting material is dissolved in a solvent that dilutes it, so spin coating cannot be performed, and a high cost and low productivity film forming method such as vapor deposition must be adopted. As an organic LE
The D element has a problem that the cost is increased, and the solution of these points becomes an issue.

[0009]

The present invention is characterized by containing polyazomethine represented by the following general formula (1) as a specific means for solving the above-mentioned conventional problems. The problem is solved by providing an organic LED element.

Embedded image

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described with reference to FIG.
A detailed description will be given based on the fourth embodiment. In addition, in order to facilitate understanding in the following description, in each layer for forming the organic LED element, the layer having the same function is denoted by the same reference numeral, and the film forming method and the like will be described. Description of some of the overlapping portions will be omitted.

A reference numeral 10 in FIG. 1 is a first embodiment of the organic LED element according to the present invention. The organic LED element 10 in the first embodiment has a substrate 1, an anode 2 and a positive electrode. The hole injecting and transporting layer 3, the light emitting layer 4, the electron injecting and transporting layer 5, and the cathode 6 are formed.

The substrate 1 is formed of a transparent material such as glass or resin, and the anode 2 is formed by depositing a transparent conductive film such as ITO on the substrate 1 by vapor deposition or sputtering. The layers 1 and 2 are formed in the same manner as described in the conventional example.

In the present invention, the hole injecting and transporting layer 3 made of polyazomethine is formed on the anode 2. The hole injecting and transporting layer 3 may be formed by using H ₂ N—R ₁ —NH
₂ and OHC-R ₂ -CHO as monomers, polymerized in an organic solvent such as m-cresol or benzene, and the obtained polyazomethine is formed on the anode 2 by a wet film-forming method such as spin coating or dip coating. The first method in which a high molecular weight polyazomethine film is obtained by forming a film on the substrate and then heating at about 300 ° C. in an atmosphere of an inert gas.

Alternatively, H ₂ N--R ₁ --NH ₂ and OHC
—R ₂ —CHO as a monomer, and these are 10 ⁻⁴ to 1
Any method of the second method for obtaining a polyazomethine polymer film by co-deposition under a vacuum of 0 ^-5 Torr and heating this at about 300 ° C. in an atmosphere of an inert gas may be used. is there.

On the hole injecting and transporting layer 3 obtained as described above, a light emitting material such as coumarin 6, DCM 1 or tetraphenylbutadiene having a structural formula shown in FIG. A film is formed, and an electron transporting material such as an oxadiazole derivative having a structural formula shown in FIG. 3 or a diphenoquinone derivative having a structural formula shown in FIG. Further, a cathode material such as Mg: Ag, Al, Al: Li is vapor-deposited on the electron injecting and transporting layer 5 to form a cathode 6, thereby completing the organic LED element 10.

It is to be noted that the layers up to the hole injecting and transporting layer 3 are formed in the same process as in the first embodiment, and the 8-hydroxyquinoline aluminum complex whose structural formula is shown in FIG. A light emitting material such as a perinone derivative having a structural formula is vapor-deposited to form a light emitting layer 4, and the above M is formed on the light emitting layer 4.
g: an organic L in which a cathode 6 of Ag or the like is formed and the electron injecting and transporting layer 5 is omitted as shown in FIG. 7 as a second embodiment.
The ED element 20 is also good.

Next, the organic L of the present invention having the above structure
The operation and effect of the ED elements 10 and 20 will be described.
First, since the hole injecting and transporting layer 3 is formed of a polymer polyazomethine film according to the present invention, the hole injecting and transporting layer 3 has excellent heat resistance. It is possible to prevent thermal deterioration due to processing heat in the above and heat generated while driving the element.

Secondly, since the hole injecting and transporting layer 3 is a high molecular weight polyazomethine film, the hole injecting and transporting layer 3 itself is spin-coated as described in the first method. Can be formed by the wet film forming method, and the production process is simplified, and even if the film formation of the light emitting layer 4 that is subsequently performed is wet, it has excellent solvent resistance and does not cause dissolution or the like. Can be one.

FIG. 8 shows an organic LED element 30 according to the third embodiment of the present invention. In the third embodiment,
H ₂ described as the first method in the first embodiment is used.
Coumarin 6, DC in polyazomethine obtained by polymerizing N—R ₁ —NH ₂ and OHC—R ₂ —CHO as monomers in an organic solvent such as m-cresol or benzene
M1 or tetraphenyl butadiene (see Figure 2)
And the like are mixed, a wet method such as spin coating is used to form a film on the anode 2, and heat treatment is performed to form the light emitting layer 4
Is what you get.

In forming the light emitting layer 4, H ₂ N—R ₁ —NH ₂ and OHC—R ₂ are formed on the anode 2 as described as the second method in the first embodiment.
_The light emitting layer 4 may be obtained by co-evaporating a monomer such as _2- CHO and a light emitting material such as coumarin 6, DCM1, and tetraphenyl butadiene and heating.

Then, as in the first embodiment, an electron transporting material such as an oxadiazole derivative (see FIG. 3) or a diphenoquinone derivative (see FIG. 4) is vapor-deposited on the light emitting layer 4 to inject electrons. The transport layer 5 is formed, and a cathode material such as Mg: Ag is vapor-deposited on the electron injecting and transporting layer 5 to form the cathode 6, thereby forming the organic LED element 30. At this time, the electron injecting and transporting layer 5 may be omitted, and the cathode 6 may be directly formed on the light emitting layer 4 to form the organic LED element 40 of the fourth embodiment as shown in FIG. Is.

As described above, even if the light emitting layer 4 is a high molecular weight polyazomethine film, the light emitting layer 4 is wet-coated by spin coating or the like, as described in the first and second embodiments. The film can be formed by the film forming method described above, the production process can be simplified, and thermal deterioration due to heat of processing in the subsequent process and heat generated during device driving after completion can be prevented.

[0023]

As described above, according to the present invention, the hole injecting / transporting layer or the light emitting layer of the organic LED element is
By using polyazomethine represented by the general formula of R ₁ —CH═N—R ₂ —N═CH —) —, a hole injecting and transporting layer or a light emitting layer having excellent heat resistance can be obtained. It is assumed that thermal deterioration does not occur due to the processing heat in the above, or the heat generated during driving after completion.
This makes it possible to extend the life of the D element and has an extremely excellent effect of improving reliability.

Further, with the above structure, the hole injecting and transporting layer formed of the polyazomethine or the light emitting layer itself can be formed into a film by a wet method such as spin coating, and the production process can be simplified, and the hole injecting and transporting can be performed. When the layer is formed from the above polyazomethine, the excellent solvent resistance of the polyazomethine allows the light emitting layer to be formed later to be wet film-formed, thereby simplifying the production process of the organic LED element. Thus, it is possible to achieve an extremely excellent effect in improving the productivity and reducing the cost of this type of organic LED element.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment of an organic LED element according to the present invention.

FIG. 2 is a structural formula showing tetraphenylbutadiene which is a light emitting material of an organic LED element according to the present invention.

FIG. 3 is a structural formula showing an oxadiazole derivative which is an electron transport material of the organic LED element according to the present invention.

FIG. 4 is a structural formula showing a diphenoquinone derivative which is an electron transport material of an organic LED element according to the present invention.

FIG. 5 is a structural formula showing an 8-hydroxyquinoline / aluminum complex which is a light emitting material of the organic LED element according to the present invention.

FIG. 6 is a structural formula showing a perinone derivative which is a light emitting material of an organic LED element according to the present invention.

FIG. 7 is an explanatory view showing a second embodiment of the organic LED element according to the present invention.

FIG. 8 is an explanatory view showing a third embodiment of an organic LED element according to the present invention.

FIG. 9 is an explanatory view showing a fourth embodiment of the organic LED element according to the present invention.

FIG. 10 is an explanatory diagram showing a conventional example.

FIG. 11 is an explanatory diagram showing another conventional example.

[Explanation of symbols]

 10, 20, 30, 40 ... Organic LED element 1 ... Substrate 2 ... Anode 3 ... Hole injecting / transporting layer 4 ... Emitting layer 5 ... Electron injecting / transporting layer 6 ... Cathode

Claims (3)

[Claims] 1. An organic LED device comprising a polyazomethine represented by the general formula (1). Embedded image 2. The organic LED device according to claim 1, wherein the polyazomethine of the general formula (1) is used in a hole injecting and transporting layer. 3. The organic LE according to claim 1, wherein the polyazomethine of the general formula (1) is used in a light emitting layer.
D element.