JPH0782552A - Organic electroluminescent element - Google Patents

Abstract

PURPOSE:To provide an organic electroluminescent element more excellent in luminance and durability than conventional elements in which an aluminum quinolinol complex is used as the luminous layer. CONSTITUTION:This element is prepared by laminating an anode, a hole transport layer, a luminous layer and a cathode in the given order, and the luminescent material of the luminous layer comprises a bipyridyl derivative represented by the formula (where in R1 is hydrogen, hydroxyl, amino, lower alkyl, alkylamino, alkoxyl, or an aromatic hydrocarbon group; n is an integer of 1-5, and R2 to R7, which may be the same or different from each other, are hydrogen, halogen, cyano, lower alkyl, alkylamino, alkoxyl or aromatic hydrocarbon groups).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device used for a flat light source or a display, and more particularly to an organic electroluminescent device having excellent brightness.

[0002]

2. Description of the Related Art As an electroluminescence element which emits light when an electric field is applied and is used for, for example, a flat light source or a display, an inorganic electroluminescence element using a ZnS / Mn-based inorganic material for a light emitting layer has already been put into practical use. However, this inorganic electroluminescent element has a drawback that it requires a complicated driving method because the driving voltage is as high as about 200 V, resulting in a high cost.

On the other hand, an organic electroluminescence device has a structure in which an anode / hole transport layer / light emitting layer / cathode are laminated, and uses an organic compound as a light emitting material for forming the light emitting layer. Unlike the luminescence element, it does not require a high driving voltage and has an advantage of high brightness.

For example, a material using an aluminum quinolinol complex as a light emitting material for forming the light emitting layer is as follows:
A brightness of 1000 cd / m ² was achieved at a driving voltage of 10 V (Appl. Phys. Lett., 51 ,
913 (1987)), further research is underway.

[Problems to be Solved by the Invention]

However, from the viewpoint of practical use,
It must be said that current organic electroluminescent elements are insufficient in terms of brightness.

The present invention has been made for the purpose of solving the above-mentioned drawbacks of the prior art and providing an organic electroluminescence device which is superior in brightness and durability to a conventional product using an aluminum quinolinol complex in a light emitting layer. .

[0007]

In order to achieve the above object, the structure of the organic electroluminescent device adopted by the present invention is an organic electroluminescent device comprising an anode, a hole transport layer, a light emitting layer and a cathode, which are sequentially laminated. At
As a light emitting material forming the light emitting layer, the following formula (1)

[Chemical 3] (In the formula, R ₁ is a hydrogen atom, a hydroxyl group, an amino group,
A lower alkyl group optionally having substituent (s), an alkylamino group optionally having substituent (s), an alkoxy group optionally having substituent (s), an aromatic carbon atom optionally having substituent (s) Hydrogen, n represents an integer from 1 to 5, (R ₁ ) _n
Are the same or different and R ₁ are bonded by the number represented by n, and R _{2 to} R ₇ are the same or different and each represent a hydrogen atom, a halogen atom, a cyano group or a substituent. Indicates a lower alkyl group which may have, an alkylamino group which may have a substituent, an alkoxy group which may have a substituent, and an aromatic hydrocarbon which may have a substituent. . ) It is characterized by using the bipyridyl derivative represented by.

The present invention will be described in detail below.

As shown in FIG. 1, the organic electroluminescence device of the present invention has a substrate having a structure in which an anode, a hole transport layer, a light emitting layer and a cathode are sequentially laminated. The base is preferably formed on a supporting substrate as shown in FIG.

Indium tin oxide (ITO), tin oxide, zinc oxide, copper iodide, etc. are used as materials for the anode, and arylamine derivatives, phenylenediamine derivatives, etc. are used as materials for the hole transport layer. Hydrazone derivative, stilbene derivative, triazole derivative,
Diazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, etc., and materials for the cathode include gold, aluminum, magnesium, indium, silver, bismuth, gallium, lithium, manganese, niobium, strontium. ,
Examples thereof include metals such as zinc, alloys, mixtures, and the like, and examples of the material forming the supporting substrate include glass, transparent plastic, quartz, and the like.

The above-mentioned structure of the substrate and the material of each layer constituting them are the same as those used in the conventional organic electroluminescence device.

Thus, the organic electroluminescent element of the present invention has a light emitting material for forming the light emitting layer,
Formula (1),

[Chemical 4] It is characterized by using a bipyridyl derivative represented by

In the above formula, R ₁ is a hydrogen atom, a hydroxyl group, an amino group, a lower alkyl group which may have a substituent, an alkylamino group which may have a substituent in the alkyl group, an alkyl group. It represents an alkoxy group which may have a substituent in the group, and an aromatic hydrocarbon which may have a substituent in the alkyl group.

Further, n represents an integer from 1 to 5, and (R
The expression ₁ ) _n indicates that the same or different substituents contained in R ₁ are bonded to the benzene ring by the number represented by n.

R _{2 to} R ₇ are the same or different and each is a hydrogen atom, a halogen atom, a cyano group, a lower alkyl group which may have a substituent or an alkyl which may have a substituent. An amino group, an alkoxy group which may have a substituent and an aromatic hydrocarbon which may have a substituent are shown.

The bipyridyl derivative used in the present invention includes, among others,

[Chemical 5] (Wherein R _{1 to} R ₇ represent the same substituents as described above) are preferred, and the aromatic hydrocarbon which may have a substituent has 5 to 8 carbon atoms. Those are preferable.

Specific examples of the bipyridyl derivative used in the present invention are as follows. Derivatives (a), (b)

[Chemical 6] Derivatives (c), (d)

[Chemical 7] Derivatives (e), (f)

[Chemical 8] Derivatives (g), (h)

[Chemical 9] Derivatives (i), (j)

[Chemical 10] Derivatives (k), (l)

[Chemical 11] Derivatives (m), (n)

[Chemical 12] Derivatives (o), (p)

[Chemical 13] Derivatives (q), (r)

[Chemical 14] Derivatives (s), (t)

[Chemical 15] Derivatives (u), (v)

[Chemical 16]

In order to manufacture the above-mentioned organic electroluminescence device of the present invention, a supporting substrate (preferably, indium tin oxide (ITO)) which is previously formed as an anode is preferably formed by using a general vacuum vapor deposition apparatus. Then, the hole transport layer material, the above-mentioned bipyridyl derivative as a light emitting material, and the cathode material may be sequentially deposited on the transparent material).

The following ranges can be exemplified as the conditions for the vapor deposition. Support substrate temperature 10 to 30 ° C., preferably 15 to 2
5 ° C. vacuum degree 1 × 10 ^{−5 to} 5 × 10 ⁻⁷ torr, preferably 1
× 10 ^{−5 to} 5 × 10 ⁻⁵ Torr vapor deposition rate 4 to 30 nm / min, preferably 8 to 13
nm / min

The following ranges can be exemplified as the thickness of each layer in the organic electroluminescent element of the present invention thus manufactured. Anode 50 to 1000 nm, preferably 100 to 3
00 nm hole transport layer 5 to 1000 nm, preferably 10 to 100 nm light emitting layer 5 to 1000 nm, preferably 10 to 10
0nm cathode 50nm or more

Hereinafter, the present invention will be described in more detail with reference to examples.

[0022]

【Example】

Example 1 A glass substrate 2 on which a layer 1 of indium tin oxide (ITO) having a film thickness of 100 nm is formed as shown in FIG.
(25 mm × 25 mm × 1.0 mm) was used as a supporting substrate. This transparent support substrate was first ultrasonically cleaned with pure water for 10 minutes, further ultrasonically cleaned with isopropyl alcohol for 10 minutes and then dried, and fixed to a substrate holder of a vacuum vapor deposition apparatus. N, N'-bis (3-methylphenyl) -1,1'-biphenyl-on a resistance heating boat made of tungsten.
5 mg of 4,4′-diamine (TAD) was placed, and 10 mg of the above bipyridyl derivative (a) was placed in another tungsten resistance heating boat, which was attached to a vacuum vapor deposition apparatus.

Next, 23 m of magnesium-silver alloy is placed in the crucible.
g was added and attached to the vacuum vapor deposition apparatus, and the pressure inside the bell jar was reduced to 1.5 × 10 ⁻⁵ Torr. After that, the boat containing TAD was energized and heated to be vapor-deposited on the transparent support substrate to form a hole transport layer 3 having a film thickness of 500 nm. Further, the boat containing the bipyridyl derivative represented by the above formula (a) was energized and vapor-deposited on the hole transport layer on the transparent supporting substrate to obtain a light emitting layer 4 having a film thickness of 500 nm. Finally, a crucible containing a magnesium-silver alloy is energized and heated to vapor-deposit it on the light emitting layer to form a magnesium-silver alloy counter electrode (cathode) 5 having a film thickness of 1000 Å. Finished.

When a direct current was applied with the ITO layer of the electroluminescent device of the present invention obtained as described above as the positive electrode and the magnesium silver alloy layer as the negative electrode, a blue-green color of 10,000 cd / m ^{2 at} a driving voltage of 10 v was applied. A luminescence was obtained.

Examples 2 to 9 By the same operation as in Example 1 above, other examples of the electroluminescent device of the present invention were produced using various bipyridyl derivatives. The results are shown in Table 1 below.

[Table 1]

[0026]

The above-mentioned bipyridyl derivative is a high melting point compound, and the organic electroluminescence device using this as a light emitting material has high brightness as is apparent from the above examples.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an electroluminescence device of the present invention.

[Explanation of symbols]

 1 Anode 2 Substrate 3 Hole Transport Layer 4 Light Emitting Layer 5 Cathode

Claims (2)

[Claims] 1. In an organic electroluminescence device comprising an anode, a hole transport layer, a light emitting layer and a cathode, which are sequentially laminated, the light emitting material forming the light emitting layer is represented by the formula (1): (In the formula, R ₁ is a hydrogen atom, a hydroxyl group, an amino group,
A lower alkyl group optionally having substituent (s), an alkylamino group optionally having substituent (s), an alkoxy group optionally having substituent (s), an aromatic carbon atom optionally having substituent (s) Hydrogen, n represents an integer from 1 to 5, (R ₁ ) _n
Are the same or different and R ₁ are bonded by the number represented by n, and R _{2 to} R ₇ are the same or different and each represent a hydrogen atom, a halogen atom, a cyano group or a substituent. Indicates a lower alkyl group which may have, an alkylamino group which may have a substituent, an alkoxy group which may have a substituent, and an aromatic hydrocarbon which may have a substituent. . ) The organic electroluminescent element characterized by using the bipyridyl derivative represented by these. 2. The bipyridyl derivative has the formula (2): (In the formula, R ₁ is a hydrogen atom, a hydroxyl group, an amino group,
A lower alkyl group optionally having substituent (s), an alkylamino group optionally having substituent (s), an alkoxy group optionally having substituent (s), an aromatic carbon atom optionally having substituent (s) R _{2 to} R ₇ are the same or different, and each is hydrogen atom, a halogen atom, a cyano group, a lower alkyl group which may have a substituent, an alkylamino group which may have a substituent. , An alkoxy group which may have a substituent and an aromatic hydrocarbon which may have a substituent. ] The organic electroluminescent element of Claim 1 represented by these.