JPH0451494A - Organic electroluminescent element and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an EL element whereby a definition picture can be obtained by having an insulating layer which is held between an organic electroluminescent layer and at least one-end electrode and also extendedly exists along the edge portion of the electrode. CONSTITUTION:An EL element is formed by laminating plural transparent electrodes 2 each made of ITO or the like, and insulating layer 9 having an opening W which exposes each of the first electrodes 2 thereon in such a manner as to rest upon each of the transparent electrodes 2 and also upon the edge portion of each of subsequently formed second electrodes, a uniform positive-hole transport layer 10, a uniform organic EL layer 14 and plural back electrodes 6 respectively crossing the transparent electrodes 2 sequentially upon a glass transparent-substrate 1. Hereupon, the EL layer serving for electro-luminescence is demarcated in the shape of a matrix up to the circumference of the part W where the insulating layer is nonexistent between the intercrossed portions of the electrodes 2, 6, and the insulating layer 9 exists in such a manner as to surround each individual electroluminescent region.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electroluminescent device having an organic electroluminescent layer that emits light upon application of a '1' field, and a method for manufacturing the same.

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

When classified according to the EL hydrogen structure, there are two types: 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 which has an insulating layer between the two layers, and the AC type is suitable as a dot 7 matrix EL element.

Further, when classified by the material of the EL layer that emits EL hydrogen atoms, there are two types: 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, organic EL strings X,
An example of a Y matrix type is shown. On the EL hydrogen element and the glass transparent substrate 1, a plurality of transparent electrodes 2 such as ITO, a hole transport layer 10, an organic EL layer 4, and a plurality of back electrodes 6 intersecting the transparent electrodes 2 were laminated and formed in order. It is something. The organic EL device 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 an organic EL device (not shown).
A three-layer structure in which an organic electron transport layer is further disposed between layer] 4 and back electrode 6 is known. Organic EL layer] 4 is a layer containing, for example, a coumarin compound. Further, as shown in FIG. 5, the back electrode 6 is usually coated with a protective layer 15 that protects the back electrode 6 and prevents short circuits. Incidentally, FIG. 4 shows a sectional view taken from the direction ■--■ in FIG. 5.

In the organic EL element, the organic hole transport layer 10 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 a transparent electrode and a glass substrate. and will be released to the outside.

As shown in the plan view of FIG. 6 viewed from the transparent electrode 2 side (members other than the electrodes are omitted),
Since the structure is a n, Yn matrix, the crossed electrodes 2 and 6
A pixel, that is, a light emitting region A is formed in the EL layer in the sandwiched and overlapping region.

However, when current is applied between X and Y of each electrode 2 and 6, X, Y2 and X2Y other than the intersection of x and y may also emit light (light emitting region B). So-called crosstalk occurs. Furthermore, the portion C around the light emitting area A may also emit light.

That is, because there is only one EL layer, crosstalk occurs in neighboring pixels and around the pixels. For this purpose, EL
When used in a hydrogen element display device, the resolution of the device as a whole decreases, making it impossible to obtain fine images.

Summary of the Invention [Object of the Invention] An object of the present invention is to provide a method for producing EL hydrogen particles that can provide fine images.

[Structure of the Invention] An electroluminescent device comprising an EL hydrogen element of the present invention, a plurality of pairs of electrodes facing each other, and an organic electroluminescent layer disposed between the electrodes, the organic electroluminescent layer and at least one The invention is characterized by comprising an insulating layer sandwiched between the electrodes and extending along the edges of the electrodes.

The method for manufacturing an EL element of the present invention includes a plurality of electrode pairs facing each other and an organic electroluminescent layer disposed between the electrode pairs, and a plurality of electrode pairs sandwiched between the electrode pairs of the organic electroluminescent layer. A method for manufacturing an EL device having a portion as a light emitting region, the method comprising: forming a plurality of strip-shaped first electrodes on a substrate; an insulating layer forming step of forming an insulating layer along the edge of a second electrode to be formed later; an electroluminescent layer forming step of forming an organic electroluminescent layer on the insulating layer; and an electroluminescent layer forming step of forming an organic electroluminescent layer on the insulating layer. The method is characterized by including a second electrode layer forming step of forming a plurality of band-shaped second electrodes so as to intersect with the first electrodes on the top.

[Operation of the Invention] According to the present invention, leakage current is blocked between a pair of electrodes sandwiching the EL layer of an EL element, particularly between the edge and the electrodes.
No crosstalk occurs even when power is applied to the EL element to cause it to emit light.

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 element is
A glass transparent substrate 1'' 2, a plurality of transparent electrodes 2 such as ITO
, an insulating layer 9 having an opening W exposing the first electrode 2 so as to span the transparent electrode 2 and the edge of a second electrode to be formed later, a hole transport layer 10 . -like organic EL layer 1
4. A plurality of back electrodes 6 intersecting the transparent electrode 2 are sequentially laminated and formed. In this embodiment, the EL layer for emitting light is defined in a matrix between the intersections of the electrodes 2.6 and around the portion W where no insulating layer is present, and the insulating layer is formed so as to surround each light emitting region. 9 exists.

This invention prevents leakage caused by the high surface density of charges at the edges of both electrodes. That is, when charges are distributed on the surface of a conductor, the amount of charge per unit area at a certain point is called the surface density of charges at that point. If the electric charge in the area dS on the conductor surface is dQ, the surface density is σ=dQ/dS.

For example, when a charge is applied to a spherical object, it is distributed on the spherical surface due to the symmetry of the shape, so if the charge is Q and the radius of the sphere is R, the surface density σ is as follows.

Therefore, in general conductors having various shapes, the surface density is large in the protruding portions having a small radius of curvature. Therefore, since the cross-sectional shape of each of the electrodes of the EL element is rectangular, electric charges are concentrated at the edges, causing leakage.

Therefore, according to the embodiment, even if there is a concentration of charges at the peripheral edge of the electrodes, which is a cause of leakage between the pair of electrodes 2.6, the current is blocked by the insulating layer 9.

FIG. 2 is a plan view (seen from above in FIG. 1) showing the shape of the insulating layer 9, and shows the transparent electrode 2, the back electrode 6, and the insulating layer 9.
Other members are omitted. FIG. 2(a) shows the case of FIG. 1, in which the edges of the picture electrodes face each other with an insulating layer 9 in between.

In Figure 2, the insulating layer 9 is formed along the edge of the electrode 6 so that the insulating layer 9 covers only the edge of the back electrode 6.

In order to manufacture an EL element having an insulating layer shown in Figure 2, first, as shown in Figure 3(a), a plurality of band-shaped transparent electrodes 2 are placed on the main surface of a glass substrate 1, each in parallel. Lamination is performed by sputtering method, lithography method, etc. so that Each of FIGS. 3A and 3B is a cross-sectional view corresponding to the cross section seen from the II direction in FIG. 1, and shows the insulating layer 9 shown in FIG.

Next, as shown in FIG. 3(b), an insulating layer 9 is formed so as to extend over the edge of the back electrode to be formed later (FIG. 3(b)) and cross the transparent electrode 2. Next, Figure 3 (C)
As shown in the figure, a hole transport layer]0 is uniformly and uniformly laminated on a plurality of transparent electrodes 2 by a vapor deposition method or the like.

Next, as shown in FIG. 3(d), an EL layer 14 is formed on the hole transport layer 0 along the transparent electrode 2 by vapor deposition or the like.

Next, a third layer is placed on the hole transport layer 10 on which the EL layer 14 is formed.
As shown in Figure (e), a second electrode layer 6 (back electrode) is stacked on top of the transparent electrode 2 so that it intersects with the transparent electrode 2 and its edges are located on the pair of strip-shaped insulating layers 9. Form by vapor deposition.

Next, after forming the second electrode layer 6, a protective layer is uniformly formed as in the conventional method.

In this way, the EL device of the present invention is obtained.

In this method, the insulating layer 9 may be formed as shown in FIG. 2 having an opening W smaller than the area allowed by the picture electrode.

Effects of the Invention As described above, according to the EL device of the present invention, even when power is applied to the device to emit light, only the light-emitting region emits light, and talostoke and “bleeding” of light emission around the light-emitting region are reduced. , detailed images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged perspective view of an EL device according to an embodiment of the present invention, FIG. 2 is a perspective plan view showing an insulating layer, and FIG. 3 is a partial cross-sectional view of an element member during manufacture of an EL device according to the present invention. FIG. 4 is a partial cross-sectional view of a conventional EL device, FIG. 5 is a partial cutaway perspective view of a conventional EL device, and FIG. 6 is a partial perspective plan view of a conventional EL device. Explanation of symbols of main parts 1...Substrate 2...Transparent electrode 4.14...EL layer 6...Electrode 15...Protective layer same strike

Claims (6)

[Claims] (1) 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 electroluminescent device comprising an insulating layer extending along an edge of an electrode. (2) The electroluminescent device according to claim 1, wherein a hole transport layer made of an organic compound is disposed between one of the organic electroluminescent layer and the electrode. (3) The electroluminescent device according to claim 2, wherein an electron transport layer made of an organic compound is disposed between the other of the organic electroluminescent layer and the electrode. (4) An electric field comprising a plurality of electrode pairs facing each other and an organic electroluminescent layer disposed between the electrode pairs, and in which a plurality of portions of the organic electroluminescent layer sandwiched by the electrode pairs are light emitting regions. A method for manufacturing a light emitting device, comprising: a first electrode forming step of forming a plurality of band-shaped first electrodes on a substrate; and a second electrode formed on the first electrode and along or after the edge of the first electrode. an insulating layer forming step of forming an insulating layer along the edge of the electrode; an organic electroluminescent layer forming step of forming an organic electroluminescent layer on the insulating layer; A method for manufacturing an electroluminescent device, comprising a second electrode layer forming step of forming a plurality of strip-shaped second electrodes so as to intersect with the electrodes. (5) Manufacturing the electroluminescent device according to claim 4, further comprising a hole transport layer forming step of forming a hole transport layer between the first electrode forming step and the insulating layer forming step. Method. (6) The method further comprises an electron transport layer forming step of forming an electron transport layer between the organic electroluminescent layer forming step and the second electrode layer forming step.
A method for manufacturing the electroluminescent device described above.