JPH02289676A - Electric field light emitting element - Google Patents

Abstract

PURPOSE:To obtain an electric field light emitting element, using a specific perinone derivative as a fluorescent organic compound together with other organic compounds as a light emitting layer between two electrodes, capable of readily producing elements and excellent in light emission with high brightness and durability. CONSTITUTION:The objective electric field light emitting element, obtained by laminating or mixing an organic compound (e.g. triphenylamines) having positive hole transporting ability with a fluorescent organic compound, consisting of a perinone derivative, expressed by formula I or II and having electron transporting ability at (10/90)-(90/10) weight ratio and placing the resultant thin film as a light emitting layer between two electrodes and capable of directly converting electrical field applied energy into light energy and providing planar heating elements of a large area.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a light-emitting shoe made of a luminescent substance, and by applying an electric field, the electric field applied energy can be directly converted into light energy, which makes it possible to directly convert energy from the electric field into light energy, which is different from conventional incandescent lamps. , concerning an electroluminescent device that enables the realization of a large-area planar light emitter, unlike fluorescent lamps or light emitting diodes. [Prior art] Electroluminescent devices differ in their luminescence excitation mechanisms; (1) intrinsic electroluminescence, which excites a luminescent material by local movement of electrons and holes within a luminescent layer and emits light only in an alternating electric field; Motoko and (
2) Electroluminescent devices can be divided into two types: carrier injection type electroluminescent devices, which excite a luminescent material by injecting electrons and holes from an electrode and recombining them within the luminescent layer, and operate in a DC electric field. The intrinsic electroluminescence type light emitting device (1) is generally made of ZnS with Nn and Cu.
The luminescent material is an inorganic compound added with
Requires a high AC electric field of 200V or more for driving,
It has many problems such as high manufacturing cost and insufficient brightness and durability. (2) Carrier-type electroluminescent devices have been able to achieve high brightness since thin organic compounds were used as the light-emitting layer. For example, JP-A-59-19439
3 and U.S. Pat. No. 4,720,432, green light emitting devices are disclosed in Jpn. Journal of Applied P
hysics, vol. 27, pp. 713-715 disclose yellow light-emitting devices, which are usually . IO
It emits high-intensity light under a DC electric field below OV. However, the reality is that (2) a carrier-type electroluminescent device with high brightness and durability has not yet been obtained. [Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned actual state of the prior art, and its purpose is to simplify manufacturing, emit high-intensity light, and maintain its luminous performance for a long period of time. The objective is to provide an electroluminescent device with excellent durability that lasts for a long time. [Means for Solving the Problems] In order to achieve the above-mentioned problems, the present inventors have intensively studied the constituent elements of a light-emitting layer, and as a result, they have developed an electroluminescent device in which a light-emitting layer made of an organic thin film layer is provided between two electrodes. In the element,
The light emitting layer is a thin film having a laminated structure of an organic compound having a hole transporting ability and a fluorescent organic compound having an electron transporting ability, or a thin film of a mixture of the two, wherein the fluorescent organic compound is the following formula (1) or It has been found that the above problems can be solved by using a perinone derivative represented by formula (II). (n) ・Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1(a) and FIG. 1(b) are schematic cross-sectional views of the electroluminescent device of the present invention. 1 is a glass substrate or a synthetic resin substrate, and 2 is an anode formed on the substrate, which is a vapor-deposited film of metal such as gold, platinum, or palladium, a spattered film, or a thin oxide film of tin, indium-tin, or an organic conductive thin film. etc., in order to extract luminescence. S3a, which is preferably transparent in a wavelength range of 400 nm or more, is a thin film layer of an organic compound having hole transport ability, and its thickness is 100 nm or more.
From 2000 people, preferably from 200 to 1000 people. 3b is a thin film layer of a fluorescent organic compound, the thickness of which is from 100 to 2000, preferably from 200 to too much. 3c is a thin light-emitting layer consisting of a mixed layer of an organic compound having a hole transport ability and a fluorescent organic compound, and the film thickness is 200 to 3000, preferably 40.
0 to 1500 people. In this case, the mixed composition of both components can be varied in weight composition from 10/90 to 90/10. As the organic compound having hole transport ability, it is preferable to use one that easily forms a non-quality solid;
A compound that is transparent in the wavelength range of 00 nm or more and has excellent hole transport ability is preferably used. Such substances include triphenylamines, stilbene derivatives, oxadiazoles, etc. Specific examples include:
Examples include the following: As the fluorescent organic compound, the following formula (1) or formula (I
A perinone derivative represented by I) is used.

(I) (n) In the present invention, when a thin film of a mixture of an organic compound having a hole transport ability and a fluorescent organic compound is used as a light-emitting layer, the composition varies from 10/90 to 90/10 by weight. be able to. The mixed thin film can be formed by vacuum evaporation method,
This can be done by coating method, melt contact method, etc. In the case of vacuum evaporation, simultaneous evaporation can be performed using two resistance heating evaporation sources whose heating temperatures can be measured independently and the evaporation rate can be controlled. A good mixed fermentation membrane can also be created by pre-mixing fine powders of both substances in one resistance heating source and vapor depositing the mixture. It is also possible to create a mixed film with a compositional change in the film thickness direction by depositing two independent substances while varying their deposition rates independently. 4 is a cathode, and organic conductors, metals that can be vacuum-deposited, etc. can be used as the material, but M
Metals with small work functions such as g, Al, Ag, and In are desirable. The cathode is formed on the light-emitting layer by, for example, vacuum deposition of a metal. In the electroluminescent device of the present invention, one or several organic layers may be inserted between the light emitting layer and the electrode in order to improve the durability and luminous efficiency of the device. [Effects] The electroluminescent device of the present invention has advantages because the specific perinone derivative represented by the formula (1) or formula (II) is used in the light emitting layer. It has many advantages, such as easy production of 11 cells, high luminance emission, and durability. [Example] The present invention will be explained in more detail with reference to Examples below. Example 1 As an anode, indium-tin oxide (ITO) glass (manufactured by HOYA) was cleaned with a neutral detergent and then ultrasonically cleaned in ethanol for about 10 minutes. This was placed in boiling ethanol for about 1 minute, and after being taken out, it was immediately blown dry. Next, N,N'-diphenynolyne N,N'- which is an organic compound with hole transport ability was placed on the glass plate.
(3-methylphenyl)-1.1'-biphenyl-4.
An organic compound layer (hole transport layer) with hole transport ability was formed by vapor depositing 4'-diamine (TPO) using a resistance heating source with a set heating temperature and controllable vapor deposition rate. That is, a tantalum boat containing TPD was controlled at 200°C using a temperature controller, and the deposition rate was maintained at 2 people/S. The degree of vacuum during vapor deposition is 0.7 x 10'
'' torr, and the substrate temperature was 20°C. The thickness of the vapor deposited layer formed on the ITO was 500.
A fluorescent organic compound of the following formula (1) is provided on the hole transport layer.
A fluorescent organic compound layer was formed by vapor depositing a perinone derivative represented by ) using a resistance heating source whose heating temperature was set and the vapor deposition rate could be controlled.

That is, the boat containing the perinone derivative was controlled at 250°C by a temperature controller, and the deposition rate was 2 people/250°C.
It was kept so that s. The thickness of this layer formed on TPD was 500. Next, a Mg-Ag electrode of 0.1 aJ and a film thickness of 1,500 nm was deposited on this fluorescent organic compound layer. The thus obtained light emitting device exhibited orange light emission with a peak of 58 on when a positive bias was applied on the ITO side. In addition, the driving voltage is 12V, the current density is 100
At mA/aJ, it exhibited a luminance of 1500cd/rd. Furthermore, this Φ light-emitting element could be operated in air with sufficient humidity removed. Furthermore, this light emitting element was heated at a current density of 10 mA and a brightness of 150 cd.
/rrr, but no decrease in brightness was observed even after 40 hours. Example 2 A light emitting device was produced in the same manner as in Example 1 except that a perinone derivative represented by the following formula (n) was used as the fluorescent organic compound. The thickness of the deposited film formed on ITO is 10
There were 00 people. The obtained light emitting device exhibited orange luminescence with a peak at 600 nm, and the driving voltage was 13 V.
It exhibited a brightness of 500 cd/rd at a current density of 100 mA/aJ. Furthermore, the light emitting device of the present invention has a current density of 10@A/
ad, when driven under conditions of brightness 150 cd/aJ, but 40
No decrease in brightness was observed over time.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views of an example of an electroluminescent device according to the present invention. 1 is a substrate, 2 is an anode, and 3a is a thin film layer of an organic compound having hole transport ability. 3b is a thin film layer of a fluorescent organic compound;
c is a thin film layer made of a mixture of an organic compound having a hole transport ability and a fluorescent organic compound, and 4 is a cathode. Figure 1 (a.) Figure 1 (b)

Claims (1)

[Claims] (1) In an electroluminescent device in which a light-emitting layer made of an organic thin film layer is provided between two electrodes, the light-emitting layer is a thin film with a laminated structure of an organic compound having a hole-transporting ability and a fluorescent organic compound having an electron-transporting ability. or a mixture thin film of both,
The fluorescent organic compound has the following formula (I) or formula (II)
An electroluminescent device characterized by being a perinone derivative represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II)