JPH0467596A - electroluminescent device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an organic electroluminescent device having an organic electroluminescent layer that emits light upon application of an electric field.

BACKGROUND ART Braun tubes are widely used as color display devices that display multiple colors in response to electrical signals. Liquid crystal elements have also been developed to make devices thinner.

Furthermore, an EL element using electroluminescence (hereinafter referred to as EL), that is, an electroluminescent element, which is a completely solid-state type and can provide high-intensity light emission, has also been developed.

Such EL elements can be classified by structure: DC type, which does not have an insulating layer or dielectric layer between the electrode and the EL layer; and
It is classified as an AC type that has an insulating layer between the layers, and the AC type is suitable as a dot matrix EL element.

Further, when EL elements are classified by the material of the EL layer that emits light, they are divided into those having an inorganic EL layer made of an inorganic substance and those having an organic EL layer made of an organic substance.

In recent years, organic EL elements that emit light with low power and high brightness have attracted attention.

In FIGS. 4 and 5, X, which is an organic EL element,
An example of a Y matrix type is shown. FIG. 4 shows a sectional view taken along the line ■--■ in FIG. The EL element includes a glass transparent substrate 1, a plurality of transparent electrodes 2 such as ITO, and a hole transport layer 1.
0. A plurality of back electrodes 6 intersecting an organic EL layer 14 and a transparent electrode 2 are laminated and formed in order. The organic EL element may have a two-layer structure consisting of a hole transport layer 10 and an organic EL layer 14 as shown in the figure, or a two-layer structure consisting of an organic EL layer 1 (not shown).
A three-layer structure in which an organic electron transport layer is further disposed between the electrode 4 and the back electrode 6 is known. The organic EL layer 14 is
For example, it is a layer containing a coumarin compound. Further, as shown in FIG. 6, the back electrode 6 is usually coated with a protective layer 15 that protects the back electrode 6 and prevents short circuits.

In the organic EL element, the organic hole transport layer 1o has a function of facilitating injection of holes from the electrode and a function of blocking electrons, and the organic electron transport layer has a function of facilitating injection of electrons from the electrode. ing.

In an organic EL element, excitons are generated by the recombination of electrons and holes injected from a pair of electrodes, and in the process of radiation deactivation of these excitons, light is emitted, and this light is transmitted through the transparent electrode and glass substrate. and will be released to the outside.

However, since organic EL elements do not have good luminous efficiency, especially when the efficiency decreases, electrical energy is converted to thermal energy, and the pixel temperature of the EL element increases. As the temperature rises, crystallization progresses and eventually the concentrated current causes destruction of the pixel portion of the device. If a pixel on the EL element surface is partially destroyed and conduction occurs, it will no longer be possible to emit light.

Summary of the Invention [Object of the Invention] An object of the present invention is to provide an organic EL element that can provide fine images and has a long life.

[Structure of the Invention] The organic EL element of the present invention includes a plurality of electrode pairs facing each other and an organic EL layer consisting of a group of island regions independently existing in each of a plurality of regions sandwiched by the electrode pairs. The electroluminescent device is characterized in that each of the island regions is composed of a plurality of independent small island portions.

Furthermore, the organic EL device of the present invention is an electroluminescent device comprising a plurality of pairs of electrodes facing each other and an organic EL layer disposed between the electrodes, wherein the organic EL device It is characterized by comprising an insulating material layer sandwiched between the electrodes and having a plurality of mutually independent through holes between the electrodes.

[Function of the Invention] According to the present invention, a light emitting region, which is a pixel between a plurality of electrode pairs of an organic EL element, is formed by a plurality of independent small dots obtained by further dividing an island-like EL layer, or between electrodes of an insulating material layer. Since the EL layer is formed with small dots emerging from a plurality of through-holes, even when power is applied to the EL element, heat dispersion due to light emission prevents temperature rise and thermal damage to the EL element.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an organic EL device according to an example. The EL device shown in FIG. 1(a) consists of a glass transparent substrate 1, a plurality of transparent electrodes 2 such as lTo, a hole transport layer 10. Multiple independent islands 1
An organic EL layer 14 consisting of 4a and a plurality of back electrodes 6 intersecting the transparent electrode 2 are laminated and formed in order. In this EL element, island-shaped light emitting regions 14, each of which is made up of a portion of a plurality of small island portions 14a, are defined in a matrix between the intersections of the electrodes 2.6 as the EL layer, and surround the individual light emitting regions and electrodes. A protective layer 15 made of an insulating material is laminated as shown.

The light-emitting part of the organic EL is not emitted entirely within a certain area, but is divided into small dots, that is, a small island part 14 that is divided into small areas.
(a) Since this aggregate is used as one light-emitting part, heat is dispersed, and even if the concentrated power is destroyed, the light-emitting region is limited to a part of the small island, and the effect on the entire EL element can be reduced.

In order to manufacture such an EL element, first, as shown in FIG. 2(a), a plurality of band-shaped transparent electrodes 2 are formed on the main surface of a glass substrate 1 by sputtering and lithography so that the electrodes are parallel to each other. Laminated by etc.

Next, as shown in FIG. 2(b), the hole transport layer 10 is uniformly laminated on the plurality of transparent electrodes 2 by a vapor deposition method or the like.

Next, as shown in FIG. 2(c), groups 14 of a plurality of small islands 14a are formed on the hole transport layer 10 by vapor deposition or the like.
An EL layer made of an organic EL material, which is a set of organic EL materials, is formed along the transparent electrode 2. In this way, the EL layer 14 of a plurality of independent light emitting regions arranged in a matrix is formed.

Moreover, here, as shown in FIG. 1(b), the small island portion 14a
The EL material may be formed by filling small holes in the insulating material layer so that the EL material is surrounded by the insulating material layer 16.

Next, on the hole transport layer 10 on which the EL layer 14 is formed, a second
As shown in Figure (d), the second electrode layer 6 is deposited on top of the transparent electrode 2 so as to intersect with the transparent electrode 2 and to correspond to each other so that each of the EL layers 14 forms an intersection point.

Next, after forming the second electrode layer 6, as shown in FIG. 2(e), an insulating material layer 15 is uniformly formed.

In this way, the EL element of the present invention shown in FIG. 1(a) is obtained.

Furthermore, in addition to FIGS. 1(a) and 1(b), the EL element of the other embodiment shown in FIG. 1(c) has an IT
A plurality of transparent electrodes 2 such as O, an insulating material layer 16, and a hole transport layer 1
0. An organic EL layer 14, a plurality of back electrodes 6 crossing the transparent electrode 2, and an insulating material layer 15 are laminated and formed in this order. In this EL element, the insulating material layer 16 has a plurality of mutually independent through holes 18 in the pixel portion between the electrodes 2. It is defined in a matrix between the intersection points of .6. If the insulating material layer 16 can divide pixels into small dots, E
It may be placed between the L layer 14 and the back electrode 6 or between the hole transport layer 10 and the EL layer 14, or between the organic EL layer and at least one electrode.

Since the light emitting portion of the organic EL element of the second embodiment is divided into small dots, that is, a small area, it is possible to disperse the emitted heat and reduce the influence on the entire pixel of the EL element. Furthermore, in the first embodiment, the light-emitting EL layer itself is formed in a dot shape, and the picture electrode is insulated by the hole transport layer, but according to the second embodiment, an insulating material layer is further provided. This improves the insulation properties. Therefore, the second embodiment is suitable for an organic EL element having a pixel light emitting area of several millimeters, such as those used in ultra-large displays that require high voltage resistance.

To manufacture such an EL element, transparent electrodes are laminated on a glass substrate 1.

Next, an insulating material layer is formed using a polymer film, coating with an insulating material such as ceramic, or a vapor deposition method.

Next, a plurality of through holes reaching the transparent electrodes are opened on the insulating material layer corresponding to the light emitting regions that will become pixels by a known etching method or the like.

Next, a hole transport layer is formed thereon in the same manner as in the above embodiment.

An organic EL layer, a plurality of back electrodes crossing the previous transparent electrode, and a protective insulating material layer are laminated and formed in this order to obtain the EL element shown in FIG. 1(c).

Furthermore, as shown in FIG. 3, the arrangement of the small island portions 14H may be a rectangular small island portion 14a between the electrodes 2 and 6, a circular small island portion 14b, or other shapes. It suffices if both are divided into 9 parts, or if the number of divisions is 2 or more. The same applies to the arrangement of a group of through holes 18.

Effects of the Invention As described above, the organic EL device of the present invention is composed of a plurality of electrode pairs facing each other and an organic EL layer disposed between the electrodes, and the organic EL layer has a plurality of overlapping electrode pairs sandwiched between the electrode pairs. Since it consists of small-area light-emitting parts that are further divided into a group of light-emitting islands that exist independently in the area, the heat generated by the organic EL element when power is applied to the element to cause it to emit light is dispersed, thereby reducing the concentration of temperature rise in the center of the pixel. This prevents heat damage to organic EL elements.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of an organic EL device according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view of an element member during manufacturing of an organic EL device according to the present invention, and FIG. 3 is a partial cross-sectional view of an organic EL device according to an embodiment of the present invention. FIG. 4 is a partial sectional view of a conventional organic EL device, and FIG. 5 is a partially cutaway perspective view of a conventional organic EL device. Explanation of symbols of main parts 1...Substrate 2...Transparent electrode 4.14...Organic EL layer 14a...Dot-shaped organic EL layer 6...・・・・・・
Electrodes 15, 16...Insulating material layer 18...Through hole Applicant Pioneer Corporation

Claims (7)

[Claims] (1) An electroluminescent element comprising a plurality of pairs of electrodes facing each other and an organic electroluminescent layer consisting of a group of island regions independently existing in each of a plurality of regions sandwiched by the electrode pairs, An organic electroluminescent device characterized in that each region is composed of a plurality of independent small islands. (2) The organic electroluminescent device according to claim 1, wherein a hole transport layer made of an organic compound is disposed between the organic electroluminescent layer and one of the electrode pair. (3) The organic electroluminescent device according to claim 2, wherein an electron transport layer made of an organic compound is disposed between the organic electroluminescent layer and the other of the electrode pair. (4) The organic electroluminescent device according to any one of claims 1 to 3, wherein the small island portion is formed by filling a group of small holes provided in an insulating material layer with an organic electroluminescent material. . (5) An electroluminescent device comprising a plurality of pairs of electrodes facing each other and an organic electroluminescent layer disposed between the electrodes, the electroluminescent element being sandwiched between the organic electroluminescent layer and at least one of the electrodes, An organic electroluminescent device comprising an insulating material layer having a plurality of mutually independent through holes between electrodes. (6) The organic electroluminescent device according to claim 5, wherein a hole transport layer made of an organic compound is disposed between one of the organic electroluminescent layer and the electrode. (7) The organic electroluminescent device according to claim 6, wherein an electron transport layer made of an organic compound is disposed between the other of the organic electroluminescent layer and the electrode.