JPH03162481A - Electroluminescent element - Google Patents

Abstract

PURPOSE:To provide an electroluminescent element having a fluorescent light- emitting layer consisting of a fluorescent thin film containing a specific 6-membered heteromonocyclic compound having dicyanomethylene group and enabling an organic fluorescent material to emit light in high efficiency and luminance. CONSTITUTION:The objective luminescent element has a fluorescent light- emitting layer consisting of a fluorescent thin film having a thickness of <=1mum and containing a 6-membered hetero-monocyclic compound having dicyanomethylene group at 4-position and expressed by formula (X is chalcogen; R<1> and R<2> are aminostyryl, alkylaminostyryl, dialkylaminostyryl, julolidine, alkyl or aryl). It is preferable to insert an organic electron-transfer layer between the cathode and the fluorescent material layer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electroluminescent device, and particularly to an electroluminescent device constructed using an organic compound as a light emitter.

BACKGROUND ART As shown in FIG. 2, this type of electroluminescent device uses an organic phosphor thin film 3 made of an organic compound and laminated on each other between a metal electrode 1 serving as a cathode and a transparent electrode 2 serving as an anode. Those with a two-layer structure in which a hole transport layer 4 is arranged, and those with a third layer structure.
As shown in the figure, a three-layer structure is known in which an organic electron transport layer 5, an organic phosphor thin film 3, and an organic hole transport layer 4 are stacked on each other between a metal electrode 1 and a transparent electrode 2. It is being Here, the organic hole transport layer 4 has a function of facilitating injection of holes from the anode and a function of blocking electrons,
The organic electron transport layer 5 has a function of facilitating injection of electrons from the cathode.

In these electroluminescent devices, a glass substrate 6 is disposed outside the transparent electrode 2, and excitons are generated by recombination of electrons injected from the metal electrode 1 and holes injected from the transparent electrode 2. The excitons emit light in the process of being radiatively deactivated, and this light is emitted to the outside via the transparent electrode 2 and the glass substrate 6.

Furthermore, in the conventional electroluminescent device having the above-mentioned structure,
Products with fluorescent bands of specific colors have been developed, but
Furthermore, in order to emit light of various other colors, it is desired to develop electroluminescent devices using more types of organic phosphors.

Summary of the Invention [Object of the Invention] The present invention has been made to satisfy the above-mentioned conventional needs, and provides an electroluminescent device that can efficiently cause an organic phosphor to emit light at a high n degree. The purpose is to

[Structure of the Invention] The electroluminescent device according to the present invention has a structure in which a phosphor emitting layer and a hole transporting layer made of an organic compound and stacked on each other are arranged between a dead electrode and an anode. ,
The phosphor emitting layer is represented by the following structural formula (A), in which X is a chalcogen atom, and R1
and R2 independently represent an aminostyryl group, an alkylaminostyryl group, a dialkylaminostyryl group, a julolidine ring. Alkyl group. It is characterized by comprising a phosphor thin film containing a six-membered monocyclic compound having a dicyanomethylene group at the 4-position, which is a functional group selected from the group consisting of and aryl groups.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a structural diagram showing an embodiment of the present invention, in which the same parts as in FIGS. 2 and M3 are given the same reference numerals.

In the figure, a thin film of aluminum with a thickness of 1500 mm is used for the metal electrode l which is the cathode. In addition, in the cathode 1,
Metals with low work functions can be used, such as aluminum, magnesium, indium, silver, or alloys thereof, with a thickness of about 500 mm or more.

The transparent electrode 2, which is an anode, is made of indium tin oxide (1
．． T. O. ) is used with a film thickness of 2000.

In addition, the anode 2 is made of a conductive material with a large work function, for example, a conductive material having a thickness of about 1,000 to 3,000. 7. O,
Alternatively, gold having a thickness of about 800 to 1,500 gold can be used. Note that when gold is used as the electrode material, the 1G electrode 2 becomes translucent.

An organic phosphor thin film 7 and an organic hole transport layer 4 are arranged between the metal electrode 1 and the transparent electrode 2, which are laminated in order from the top in the figure.

For the organic hole transporting layer 4, a thin film of a triphenylamine derivative, for example, a compound of the following formula (1) is used.

In addition, the organic hole transport layer 4 further includes the following formulas (II) to
(Xn) C TM (Carrier
Compounds known as ansmjtlng Materials) can be used.

As the organic phosphor thin film 7, a phosphor thin film containing a six-membered monocyclic heterocyclic compound having a dicyanomethylene group at the 4-position and one chalcogen atom in the ring of the following formula (A) is used.

The thickness of the organic phosphor thin film 7 is set to 1 μm or less.

Here, in the above {8 formula (A), X is a chalcogen atom,
In other words, O, S, Se, T belonging to the periodic table ■
e or Po, and R1 and R2 independently represent an aminostyryl group, an alkylaminostyryl group. A functional group selected from the group consisting of a dialkylaminostyryl group, a julolidine ring, an alkyl group, and an aryl group (however, the alkyl component preferably has 1 to 5 carbon atoms, but 6
The aryl group preferably has 6 to 14 gU of carbon atoms, but may have 18 or more carbon atoms.

The six-membered monocyclic compound forming this phosphor thin film is the first
No. of functional groups in the table. l-No. Those having a combination of 5 are preferred.

In addition, the electroluminescent device described above has a two-layer structure in which the organic phosphor thin film 7 and the organic hole transport layer 4 are arranged between the cathode 1 and the anode 2. A three-layer structure including an organic electron transporting layer 5 made of a berylenetetracarboxyl derivative of the formula (XX) can also produce similar effects.

Effects of the Invention As explained above, the electroluminescent device according to the present invention has a structure in which a phosphor emitting layer and a hole transporting layer made of an organic compound and stacked on each other are arranged between a cathode and an anode. In the device, the phosphor emitting layer is a phosphor containing a 6-membered monocyclic heterocyclic compound having a dicyanomethylene group at the 4-position of the above formula (A) and one chalcogen atom in the ring, such as dicyanomethylene pyran dye. Since it is made of a thin film, it can efficiently emit light with high brightness at low voltage.

EXAMPLES In the following, electroluminescent devices according to examples of the present invention were fabricated and emitted from them.

First, a transparent electrode, which is an anode, is placed on a glass substrate.
A film with a thickness of 2,000 layers was prepared. Aluminum was used for the metal electrode 1 serving as the cathode.

For the organic hole transport layer 4, a triphenylamine derivative of the above formula (1) was used.

As organic phosphor thin H7, No. 1 in the above table is used. I below (
A-1) dicyanomethylenepyran dye was used.

The film conditions such as degree of vacuum, evaporation rate, and film thickness when depositing the hole transport layer, phosphor thin film, and cathode are as shown in Table 2. The luminescence characteristics obtained by applying .

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing an embodiment of the present invention, and FIG. 3 is a structural diagram showing a conventional example. Explanation of symbols of main parts 1...Metal electrode (cathode) 2...Transparent electrode (anode) 4...Organic hole transport layer 6... Glass substrate 7...Organic phosphor thin film Fig. 2

Claims (2)

[Claims] (1) An electroluminescent device having a structure in which a phosphor-emitting layer and a hole-transporting layer made of an organic compound and stacked on each other are arranged between a cathode and an anode, wherein the phosphor-emitting layer has the following structural formula (A). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the above structural formula (A), X is a chalcogen atom, and R^1 and R^2 are independently aminostyryl group, alkylaminostyryl group, dialkyl group An electric field comprising a phosphor thin film containing a 6-membered hetero monocyclic compound having a dicyanomethylene group at the 4-position, which is a functional group selected from the group consisting of an aminostyryl group, a diurolidine ring, an alkyl group, and an aryl group. Light emitting element. (2) The electroluminescent device according to claim 1, further comprising an organic electron transport layer disposed between the cathode and the phosphor layer.