JPH0384892A - Luminous element - Google Patents

Abstract

PURPOSE:To manufacture a luminous element of a good luminous efficiency easily by making charge implanting layers consist of very thin membranes on electrodes. CONSTITUTION:On glass bases 1 and 7 furnishing transparent electrodes (ITO), alcohol solution is spread, and after leaving them, the bases 1 and 7 are washed, and after baking them, an alcohol solution of vinylanthracene is spin-coated to obtain a luminous layer 4. In such a way, only by soaking the bases 1 and 7 with electrodes in a charge implanting substance solution with a coupling agent, charge implanting layers 3 and 5 almost near a single molecule can be formed on the surfaces of the electrodes 2 and 6, and by heating the bases 1 and 7, a common combination is produced between the electrodes 2 and 6 and the electrode implanting substance. As a result, the charge implanting layers 3 and 5 of a high physical and chemical strength are produced, and since the charge implanting layers 3 and 5 are made near a single molecule, a sufficient electric field can be applied to the luminous layer 4 to radiate even though the voltage to apply is low. Consequently, an element of a good luminous efficiency can easily be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a structure of a light emitting layer of a light emitting device using an organic light emitting substance.

[Prior Art] Conventionally, coating methods, vapor deposition methods, etc. are known as methods for forming charge injection layers of light emitting devices using organic light emitting substances (Proceedings of the 1989 Spring Annual Meeting of the Japan Society of Applied Physics, 3a-G- 7 etc.)
.

Coating methods include a spin code method and a roll coat method. A resistance heating method is generally used in the vapor deposition method.

[Problem M to be Solved by the Invention] However, with the coating method, it is difficult to control the film thickness, and with the vapor deposition method, a considerable amount of heat is applied to the vapor deposited material, so there is a risk that the vapor deposited material may be decomposed. In addition, organic compounds have a relatively high vapor pressure, so they sublimate easily and are difficult to form into films using vapor deposition methods.Furthermore, these methods require film thickness control on the order of tens of thousands of degrees.
If this is the case, the film thickness must be increased, and if the film thickness is increased, an electric field will drop and a sufficient electric field will not be applied to the light emitting layer. Furthermore, since it is not chemically bonded to the substrate, it lacks adhesion to the electrode.

Therefore, an object of the present invention is to provide a light-emitting element equipped with a charge injection layer that can be coated uniformly with the minimum necessary film thickness to achieve aK as a charge injection layer and has excellent adhesion to a substrate. do.

[Means for Solving the Problems] ■In a light emitting device consisting of an organic light emitting layer and a charge injection layer, and a pair of electrodes and a substrate sandwiching the layers, the charge injection layer is formed of an extremely thin film on the electrode. It is characterized by

(2) The charge injection layer is characterized in that it is made of a compound in which a coupling agent used as a surface modifier is bonded to a charge injection substance.

[Function] According to the above structure of the present invention, a large layer with nearly monomolecular charge can be formed on the electrode surface simply by dipping the substrate with the electrode in a solution of the charge injection substance with a coupling agent; A covalent bond is created between the electrode and the charge injection material. Therefore, the charge injection layer has high physical and chemical strength. Furthermore, since the charge injection layer is close to a single molecule, a sufficient electric field is applied to the light emitting layer to emit light even if the applied voltage is low.

Hereinafter, the details of the present invention will be shown by examples.

[Example 1] FIG. 1 is a cross-sectional view of a light emitting device. Here, an example is shown in which vinyl anthracene is used as the light-emitting substance and the following is used as the hole injection layer.

0.2 of (A) on a glass substrate with a transparent electrode (ITO)
% alcohol solution was applied, and after being left for 10 minutes, the substrate was cleaned with alcohol. After baking this substrate at 100°C for 5 minutes, a 5% alcohol solution of vinylanthracene was spin-coded to give a luminescent layer thickness of 2000 nm.
The thickness of the light-emitting layer may be between 500 and 1 μm, 5
If it is 00A or less, there is a possibility that a short circuit will occur when an electric field is applied. If it is 1 μm or more, the applied voltage will be too high and it is not practical.
When 0 volts were applied, light emission was observed. Organic luminescent substances include vinylanthracene, anthracene, pyrene,
Benzanthracene, perylene, tetracene, naphthacene, coronene, coumarin, cyclopentadiene, quinoline, and derivatives of these organic light-emitting substances can also be used. By using a mixture of these substances, it was possible to obtain luminescence of various colors.

[Example 2] Here, vinyl anthracene was used as a luminescent substance,
As an electron injection layer, (OEt)ssi(CH)4-P V 1' e n
An example using e---(B) is shown.

A 0.2% alcohol solution of (B) was applied onto the substrate with aluminum electrodes, and after being left for 10 minutes, the substrate was washed with alcohol. After baking this substrate at 100°C for 5 minutes, it was placed facing a transparent glass substrate with an electrode (ITO) and the distance between the substrates was set to 0. The gap was fixed at 5 μm, and vinyl anthracene was sealed in this gap at 80°C. The thickness of the light emitting layer may be between 500λ and 1 μm. If it is 500 A or less, there is a possibility that a short circuit will occur when an electric field is applied.

If it is 1 μm or more, the applied voltage becomes high and it is not practical.The DC voltage applied to the thus obtained light-emitting device3 Luminescent substances include, in addition to vinylanthracene, anthracene, pyrene, benzanthracene, perylene, tetracene, naphthacene, coronene, coumarin, Cyclopentadiene, quinoline, and derivatives of these organic light-emitting substances can be similarly utilized. By using a mixture of these substances, it was possible to obtain luminescence of various colors.

[Example 3] Here, vinyl anthracene was used as a luminescent substance,
As an electron injection layer, (OEt)3si(CH)4-Pyrene
---(B) As a hole injection layer, (OEt)3si(C)]]hNo-Z-, qNEth
An example using -(A) is shown.

A 0.2% alcohol solution of (B) was applied onto the substrate with aluminum electrodes, and after being left for 10 minutes, the substrate was washed with alcohol and baked at 100° C. for 5 minutes. Next, 0.0% of (A) was applied to the glass substrate with a transparent electrode (ITO). A 2% alcohol solution was applied, and after being left for 10 minutes, the substrate was washed with alcohol. Immediately after being left for 110 minutes, the substrate was washed with alcohol, and baked at 100° C. for 5 minutes. These two boards are placed facing each other and the distance between the boards is set to 0. Fixed at 5μm,
Vinyl anthracene was sealed in this gap at 80°C.

l! ! The thickness of the optical layer may be between 500 Å and 1 μm; if it is less than 500 λ, there is a possibility of short-circuiting when an electric field is applied. If it is 1 μm or more, the applied voltage becomes too high and is not practical. When a DC voltage of 25 volts was applied to the thus obtained light emitting device, light emission was observed. In addition to vinylanthracene, the organic light-emitting substances may be anthracene, pyrene, benzanthracene, perylene, tetracene, naphthacene, coronene, coumarin, cyclopentadiene, quinoline, and derivatives of these organic light-emitting substances. By using a mixture of these substances, it was possible to obtain luminescence of various colors.

Although the embodiments have been described above, the materials used for the charge injection layer are not limited to those shown here, and the materials used for the electrodes are not limited to those shown here.

[Effects of the Invention] As described above, according to the present invention, by using a coupling agent used as a surface treatment agent in the charge injection layer, an element with high luminous efficiency can be easily manufactured. .

[Brief explanation of drawings]

FIG. 1 is a sectional view of a light emitting element showing the basic configuration of the present invention. 1... Substrate 2... Electrode 3... Electron injection layer 4... Light emitting layer 5... Hole injection layer 6... Electrode 7... Substrate and above

Claims (2)

[Claims] (1) A light emitting device comprising an organic light emitting layer, a charge injection layer, and a pair of electrodes and a substrate sandwiching the layers, wherein the charge injection layer is an extremely thin film on the electrode. (2) The light emitting device according to claim 1, wherein the charge injection layer is made of a compound in which a coupling agent used as a surface modifier is bonded to a charge injection substance.