JPH02253593A - Luminous element - Google Patents

Abstract

PURPOSE:To obtain a flexible, a large area, and even membrane by composing a transparent conductive membrane with a laminate membrane of metal oxides and a metal, in a luminous element making the transparent conductive membrane as one side electrode, and providing an organic compound membrane layer to present the luminous function between two opposite electrodes. CONSTITUTION:A transparent conductive membranes 2 formed on a polymer film 1 is made at least as one side electrode, and an organic compound membrane layer 3 is arranged between the opposite two electrodes as the layer to present the luminous function to form a luminous element. The transparent conductive membrane 2 formed on the film 1 is a luminous element which consists of a laminate membrane of metal oxides 2-1 and 2-3, and a metal 2-2. And the metal oxide 2-1 is a luminous element which consists of In as the main component, and Sn, or Sn and Sb, while the metal 2-2 consists of Au, Ag, or Pd, or an alloy of some of them. In order to form the transparent conductive membrane 2 and the like on the film 1, a vacuum evaporation method, a spattering method, a CVD method, or the like is applied.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an electroluminescent (EL) device that emits electroluminescence (electrons are emitted from one electrode and holes are emitted from the other electrode). In an injection-type EL device that operates by injecting a polymer film, a thin organic compound layer is provided as a layer that exhibits a light-emitting function, so that it has sufficient luminance and flexibility that is provided by using a polymer film as a base material. The present invention relates to an EL element having:

[Background of the invention]

EL elements are generally classified into injection type EL elements and intrinsic type EL elements. Among these, the operation mechanism of injection-type EL elements is to apply a forward bias to a p-n junction such as a diode, and inject electrons and holes from electrodes on both sides, respectively.
Light is generated by their recombination. Generally, this EL element has a structure in which a layer that exhibits the above-mentioned light-emitting function is placed between two electrodes, and by applying a voltage between these electrodes, the light-emitting element converts electrical energy directly into light. It is. The characteristics of injection type EL elements include that they can operate in a wide driving frequency range from direct current to alternating current, can be driven with resistance voltage, have high conversion efficiency from electricity to light, and can be used in conventional light emitting devices. Unlike elements such as incandescent light bulbs and fluorescent lamps, they can be used to display elements such as lines, diagrams, images, etc. in various shapes such as gi membrane panels, belt-shaped, cylindrical, etc., or large-area panels. It is possible to realize a planar light emitting body such as the following. On the other hand, in an intrinsic type EL element, a luminescent material such as zinc sulfide doped with a transition metal or rare earth metal is provided by sandwiching a dielectric layer between two electrodes or dispersing it in a highly dielectric polymer.
It is a light emitting element that directly converts electrical energy into light by applying a relatively high alternating current voltage to the picture electrode. These intrinsic type EL elements are widely used as backlights for Fi) II panels, liquid crystal displays, etc., but they have had problems such as being unable to be driven at a low voltage.

Recently, an injection-type light-emitting diode device has been reported, which has two layers of organic compound thin films that are conductive and electronically conductive. (
C, W, Tang: App 1. Phys, Lett
, 51. (12), 193. (1987)) Light-emitting elements using this organic material are attracting attention because they have features such as being able to select from various thin film formation methods and being able to form thin films over a large area with high precision.

However, when an element is formed using only currently known organic materials for EL, the intensity of light emission is limited to some extent.
In addition, there are problems such as unstable emission intensity, so it has not been put into practical use.

There is a need for an EL device that can produce a uniform TRI film over a large area, is mass-producible, and is cost-effective. Moreover, when considering practicality, it is important to have flexibility in the element form. As a result of intensive studies, the present inventors have solved the above problems, are flexible, can produce a uniform thin film over a large area, are mass-producible, and are advantageous in terms of cost. Invented an EL element.

[Disclosure of the invention]

The present invention is a light-emitting element in which a transparent conductive film formed on a polymer film is used as at least one ms, and a thin organic compound layer is provided between two opposing electrodes as a layer that exhibits a light-emitting function. This is a light emitting element in which the transparent conductive film formed on the film is a laminated film of a metal oxide and a metal, and the metal oxide is a composite metal oxide containing indium as a main component and tin or tin and antimony. This is a light-emitting element in which the metal is gold, tin, palladium, or an alloy thereof.

Methods for forming the above-mentioned transparent conductive film on a polymer film include vapor deposition, sputtering, and chemical vapor deposition (CVD).
) Various physical or chemical thin film forming methods such as the method are used. It is particularly preferably formed by DC or RF magnetron sputtering. These thin films are number 10
It was a good product with few pinholes even though it was 1ilIll for 0 people.

The organic compound y1 film layer is composed of one type of organic compound thin film or a laminated film of two or more types of organic compound thin films.

As the organic compound, an organic compound that has a high luminous quantum efficiency, has a π-electron system that is susceptible to external perturbation, and is easily excited is preferably used.

Examples of such organic compounds include fused polycyclic aromatic hydrocarbons, P-terphenyl, 2.5-diphenyloxazole, 1. 4-b l S-(2-methylstyryl)-benzene, xanthine, coumarin, acridine, cyanine dye, benzophenone, phthalocyanine, and metal complex compounds formed from a metal and an organic ligand, as well as complexes other than the above. Cyclic compounds and their derivatives, aromatic amines, aromatic polyamines, compounds that form complexes in an excited state among compounds having a quinone structure, polyacetylenes, polysilanes, etc., or mixtures of these compounds are used. To explain more specifically the metal complex compound formed from a metal and an organic ligand, the metals forming the complex include AI, Ga,
Ir, Zn, Cd, Mg, Pb, Ta, etc. are used. Examples of organic ligands include porphyrin, chlorophyll, 8-hy)'roxyquinoline (oxine (Ox)),
Phthalocyanine, salicylaldehyde oxime, 1-nitroso-2-naphthol, cupferone, dithizone, acetylacetone, etc. are used. To explain more specifically, the oxine complexes are: 2, oxine complexes, 5.
7-dibromooxine complex (hereinafter referred to as d 1Brox), 5,7-diiodooxine complex (hereinafter referred to as d i IO
x), thiooxin complex (hereinafter referred to as Th i oox
), selenoxine complexes (hereinafter referred to as Se IOX), 5-methyloxine complexes (hereinafter referred to as MeOx), etc. More specifically, these metal complex compounds include AI (Ox)s, Zn (Ox )t, Z
n (d 1Brox)t, Zn (d
i l0x)t , Zn(ThioOx),,
Zn(SelOx)x, Bi(MeOx)x, etc. are used.

The organic compound thin film is an amorphous, microcrystalline, or amorphous containing microcrystalline, polycrystalline, or single crystalline thin film of the above organic compound.

In addition to various physical or chemical thin film forming methods such as vacuum evaporation, sublimation, coating, spin coating, and pulling methods are also effective methods for producing the organic compound thin films mentioned above. used.

The polymer film is not particularly limited as long as it has good transparency, but heat resistance may be required depending on the electrode formation conditions. Easily used materials include polyethylene terephthalate (PET), polycarbonate (PC), and polyether sulfone (PES).
), polyetheretherketone (PEEK), etc., but polyethylene (PE), polypropylene (pp)
etc. can also be used. Furthermore, not only homopolymers but also various copolymers can be used.

The metal oxide layer is made of a composite oxide containing indium as a main component and tin or tin and antimony, and preferably the ratio of tin and antimony to indium is 2 to 25 at%, more preferably , the ratio of antimony to tin is preferably 0 to 50 at%, and the thickness of each metal oxide layer is 5
The metal layer is preferably made of gold, tin, palladium, or an alloy thereof, and the thickness is preferably 10 to 500 per layer.The laminated structure is such that the metal layer is sandwiched between metal oxides. Make it. In this case, it is sufficient that the total thickness is 100 Å or more.

For the opposite electric bridge, not only the above-mentioned transparent electrode or general metal oxide electrode but also a thin film of a metal, an alloy, a metal compound such as metal silicide, or a laminated thin film of one or more of these are used.

More preferably, a material with high efficiency of electron injection into the organic light emitting layer in contact with the organic light emitting layer is preferably used.

To explain this electrode material more specifically, metals with small electron work functions, alloy thin films, and laminated thin films thereof are used for boat fishing, and more specifically, Mg,
Metals such as Li, Na, Ca, Rb, Sr, Ce,
Alloys such as Mg-Ag, CCs-0-A, Cs3 sb
,,Na,KSb.

Metal compound thin films such as (Cs)Nag, KSb, and N thin films thereof are suitable.

The device of the above invention may be stacked in multiple stages such as electrode layer/layer exhibiting a light-emitting function/electrode layer/layer exhibiting a light-emitting function/electrode layer/layer exhibiting a light-emitting function/electrode... Due to this device structure, It is also possible to adjust the color tone and create multiple colors. Also,
A large number of these elements may be arranged on a plane. In the elements arranged on this plane, the emitted light color of each element may be changed and used as a color display member.

〔Example〕

As shown in Figure 1, a PET film 1 with a thickness of 75 μm
D using an indium-tin-antimony target on top
Metal oxide film 2-1 is formed by C magnetron sputtering method.
Then, gold 22 was formed by 50 people, and metal oxide film 23, which is the same as the first layer, was formed by 200 people to form the first laminated transparent electrode layer. The composition ratio of indium, tin, and antimony in the metal oxide film at this time was 87/11/2.

Next, a thin film of aluminum oxine (Al(OX)3) with a thickness of 40 mm was deposited on this electrode layer by vacuum resistance heating vapor deposition.
0A was deposited to form an organic compound thin film layer 3. moreover,
On this layer, a Mg metal thin film was deposited by electron beam evaporation to form the second electrode layer 4, and the light emitting element of the present invention was obtained.The area of the 0Mg metal evaporation film was 3 mm square.

A direct current voltage was applied to the light emitting device of the present invention, and the current characteristics with respect to the applied voltage were investigated. The characteristics are shown in FIG. 2. When the transparent electrode was made positive and the Mg side was made negative, the IT current increased as the voltage increased, and when the polarity was the opposite, no current flowed, showing so-called diode characteristics. Also, when a voltage of 10V is applied in the forward direction of this diode, the output voltage is 100mA.
injection current was observed. When this current value was converted into a current density, it reached 1.1A/cm". Also, this device operated with both direct current and alternating current. It was also bright and clearly visible under normal indoor fluorescent lighting. A green surface luminescence was observed.The same luminescence was also observed when the polymer film was made into a cylindrical shape using its flexibility and a similar current test was conducted.

[Comparative Example 1] A test similar to that of the example was conducted using a transparent conductive film formed on a PET film by DC magnetron sputtering using an indium target as an electrode. As a result, although luminescence was observed, the luminescence intensity was low and the stability was also insufficient.

[Comparative Example 2] Indium/tin/antimony = 70/15/15 with film composition of indium, tin, and antimony on PET film
A test similar to that of the example was conducted using an electrode formed by DC magnetron sputtering so as to have the following properties. As a result, almost no luminescence was observed.

〔Effect of the invention〕

As is clear from the above Examples and Comparative Examples, the present invention relates to an injection type light emitting device, and in the prior art,
This provides a high-performance light-emitting element with flexibility that has not been achieved previously, and is industrially useful as a display member or the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of implementation of the light emitting device of the present invention. FIG. 2 is a graph showing the characteristics of the light emitting device of the present invention. In the figure: 1---Polymer film, 2...
-...-Transparent electrode layer, 2-1-...
metal oxide, 2-2 metal, 2-3...
・Metal oxide, 3 Organic compound thin film layer, 4...
---------The first and second electrode layers are shown. Figure 1

Claims (3)

[Claims] (1) A light-emitting element in which a transparent conductive film formed on a polymer film is used as at least one electrode, and a thin organic compound layer is provided between two opposing electrodes as a layer that exhibits a light-emitting function, and the polymer film A light-emitting device characterized in that the transparent conductive film formed thereon is a laminated film of a metal oxide and a metal. (2) The light emitting device according to claim 1, wherein the metal oxide is a composite metal oxide containing indium as a main component and consisting of tin or tin and antimony. (3) The light emitting device according to claim 1, wherein the metal is gold, tin, palladium, or an alloy thereof.