JPH03233891A - El(electroluminescence) element and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide fine resolution pictures by forming an electroluminescence(EL) layer with independent island area groups with each area located in each of a plural number of areas surrounded by paired electrodes. CONSTITUTION:An EL element is formed by laminating a plural number of transparent electrodes 2 e.g. ITO and the like, a positive hole transport layer 10, a plural number of independent organic EL layer 14, and a plural number of back electrodes 6 intersecting the transparent electrodes 2 in succession on a transparent glass substrate 1. Therefore a plural number of island shaped light emitting areas 14 are defined at the intersections of the electrodes 2, 4 with a protective layer 15 laminated to surround individual light emitting areas. This structure prevents electrons and positive holes from leaking through the surrounding areas of the EL layer as the leak between the paired electrodes 2, 6 is prevented. Cross talk or light leak in the area around the light emitting area is reduced to provide fine resolution pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electroluminescent device having an electroluminescent layer that emits light upon application of an electric 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 type elements have also been developed to make devices thinner.Furthermore, electroluminescence (completely solid-state type elements) that can emit high-brightness light have been developed.
Elements using EL (hereinafter referred to as EL) have also been developed.

When classified by structure, such electroluminescent elements are classified into DC type, which does not have an insulating layer or dielectric layer between the electrode and the EL layer, and AC type, which has an insulating layer between the electrode and the EL layer. The AC type is suitable as a dot matrix electroluminescent device.

Furthermore, when classifying electroluminescent elements according to the structure of the EL layer that emits light, there are two types: a dispersed type in which fine particles of an EL substance are bonded with a binder and formed by coating, and a thin film type in which an EL substance is formed by a thin film forming method such as vapor deposition or sputtering. Can be divided.

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

FIG. 4 shows a schematic cross section of an X,Y matrix type double line edge AC electroluminescent device which is an inorganic electroluminescent device. The electroluminescent device includes, on a glass transparent substrate 1, a plurality of transparent electrodes 2 such as ITO, a first insulating film 3, an inorganic EL layer 4, a second insulating film 5, and a plurality of back electrodes 6 crossing the transparent electrodes 2. are laminated and formed in order. The inorganic EL layer 4 is made of, for example, ZnS.

This layer contains a II-Vll gold metal compound semiconductor material such as Zn5e, CaS, SrS, etc. as a host material and contains several percent of a luminescent center material.

In the inorganic electroluminescent device, a voltage is applied between the back electrode 6 and the transparent electrode 2, and an electric field is applied to the inorganic EL layer 4 via the first and second insulating films 5. The applied electric field generates free electrons in the host material of the inorganic EL layer 4, and the electric field accelerates the free electrons to a high energy state. These electrons excite the luminescent center substance of the inorganic EL layer 4, and the excited state is relaxed to emit light having a predetermined spectral distribution. The color of the emitted light is determined by the combination of the host substance of the inorganic EL layer 4 and the luminescent center substance. For example, when using 2nS as the host substance, the luminescence center substance emits red light when it is Sm, similarly emits yellow light when it is Mn, and emits green light when it is Tb.
At Tm, each exhibits blue light emission.

5 and 6 show an example of an X,Y matrix type organic electroluminescent device. The electroluminescent device has a plurality of transparent electrodes 2 such as ITO, a hole transport layer 10°, an organic EL layer 14, and a plurality of back electrodes 6 intersecting the transparent electrodes 2, which are laminated in order on a glass transparent substrate 1. It is something. The organic electroluminescent device has a two-layer structure consisting of a hole transport layer 10 and an organic EL layer 14 as shown in the figure,
Although not shown, a three-layer structure in which an organic electron transport layer is further disposed between the organic EL layer 14 and the back electrode 6 is known. The organic EL layer 14 is a layer containing, for example, 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. Incidentally, FIG. 5 shows a sectional view taken along the line ■-■ in FIG. 6.

In the organic electroluminescent device, 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. are doing. In an organic electroluminescent device, 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 penetrates the transparent electrode and glass substrate. It will be released to the outside through.

Both organic and inorganic electroluminescent elements have a back electrode 6
As shown in the plan view of FIG. 7 viewed from the side, since the structure is an Xn, Yn matrix, pixels, that is, light emitting regions A are formed in the EL layer in the sandwiched and overlapping region between the crossed electrodes 2.6.

However, when current is applied between X and Y of each electrode 2.6, x, y2 and X2YI 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 of the single EL layer, crosstalk and "bleeding" of light emission occur in neighboring pixels and around the pixels. For this reason, when an electroluminescent device is used in a display device, the resolution of the device as a whole decreases, making it impossible to obtain a fine image.

Summary of the Invention [Object of the Invention] An object of the present invention is to provide an electroluminescent device capable of producing fine images and a method for manufacturing the same.

[Structure of the Invention] The electroluminescent device of the present invention is an electroluminescent device comprising a plurality of electrode pairs facing each other and an electroluminescent layer disposed between the electrode pairs, the electroluminescent layer disposed between the electrode pairs. It is characterized by consisting of a group of island regions that exist independently in each of a plurality of regions sandwiched by.

The method for manufacturing an electroluminescent device of the present invention includes a plurality of electrode pairs facing each other and an electroluminescent layer disposed between the electrode pairs, and a plurality of portions of the electroluminescent layer sandwiched by the electrode pairs. A method for manufacturing an electroluminescent device having a light-emitting region as a light-emitting region, comprising: a first electrode forming step of forming a plurality of strip-shaped first electrodes on a substrate; and a plurality of island-shaped strips formed on and along the first electrode. an electroluminescent layer forming step of forming electroluminescent layers in parallel, and a second electrode layer forming step of forming a plurality of strip-shaped second electrodes on the electroluminescent layer so as to intersect with the first electrode. It is characterized by including.

[Operation of the Invention] According to the present invention, since the EL layer is not continuously laminated between a pair of electrodes of an electroluminescent element, but is formed as an independent laminated body, there is no crosstalk even when power is applied to the element to cause it to emit light. as well as"
No "bleeding" occurs.

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

FIG. 1 shows an organic electroluminescent device according to an example.

The electroluminescent device includes a glass transparent substrate 1, a plurality of transparent electrodes 2 such as ITO, a hole transport layer 10. A plurality of independent organic EL layers 14 and a plurality of back electrodes 6 intersecting the transparent electrode 2 are sequentially laminated and formed. In this case, a plurality of island-shaped light-emitting regions 14 are defined as a matrix between the intersections of the electrodes 2.6 as the EL layer, and a protective layer 15 is laminated to surround each light-emitting region.

Therefore, according to the embodiment, leakage of electrons and holes through the periphery of the EL layer, which is a cause of leakage between the pair of electrodes 2.6, is eliminated.

In order to manufacture such an electroluminescent device, first, the method shown in FIG.
), a plurality of band-shaped transparent electrodes 2 are laminated on the main surface of a glass substrate 1 so that they are parallel to each other by sputtering, lithography, or the like.

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), a plurality of island-shaped EL layers are formed along the transparent electrode 2 on the hole transport layer 10 by vapor deposition or the like. In this way, an ELL12 type of a plurality of independent light emitting regions arranged in a matrix is formed.

Next, on the hole transport layer 10 formed in the ELL12 type, 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 ELL12 types forms an intersection point.

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

In this way, the electroluminescent device of the present invention shown in FIG. 1 is obtained.

In addition, as another example, as shown in the cross-sectional view of the organic electroluminescent device in FIG. Similarly, if they are formed independently in an island shape so as to cover the side surface of the electrode 2, it is possible to further prevent the influence of light emission due to electrical leakage.

Incidentally, FIGS. 2(a) to 3(b) and 3 show cross-sectional views corresponding to the cross-section taken along line II in FIG. 1.

In the above embodiments, the structure of an organic electroluminescent device has been described, but an inorganic EL layer may be formed independently in the form of an island as an inorganic electroluminescent device. In this case, the electroluminescent element may be an AC type that has an insulating layer or a dielectric layer between the electrode and the EL layer, or a DC type electroluminescent element that does not have an insulating layer between the electrode and the EL layer. ΦApplicable.

Effects of the Invention As described above, the electroluminescent device of the present invention is composed of a plurality of electrode pairs facing each other and an EL layer disposed between the electrodes, and the EL layer has a plurality of regions sandwiched between and overlapping by the electrode pairs. Since the device consists of a group of island regions that exist independently, even when power is applied to the element to emit light, only the light emitting region emits light, reducing crosstalk around the light emitting region and "bleeding" of light emission, and improving definition. You can get a good image.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an electroluminescent device according to an embodiment of the present invention, FIG. 2 is a partial sectional view of an element member during manufacture of an electroluminescent device according to the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. Partial cross-sectional views of example electroluminescent devices, FIGS. 4 and 5
6 is a partially cutaway perspective view of a conventional electroluminescent device, and FIG. 7 is a partial plan view of a conventional electroluminescent device. Explanation of symbols of main parts 1...Substrate 2...Transparent electrode 4.14...EL layer 6...Electrode 15...Protection layer

Claims (6)

[Claims] (1) An electroluminescent device comprising a plurality of electrode pairs facing each other and an electroluminescent layer disposed between the electrode pairs, wherein the electroluminescent layer is arranged in each of the plurality of regions sandwiched by the electrode pairs. An electroluminescent device comprising a group of independently existing island regions. (2) The electric field according to claim 1, wherein the electroluminescent layer is made of an organic compound, and a hole transport layer made of the organic compound is disposed between the electroluminescent layer and one of the electrode pair. Light emitting element. (3) The electroluminescent device according to claim 1, wherein the electroluminescent layer is made of an inorganic compound, and an insulating layer is disposed between the electroluminescent layer and the electrode pair. (4) An electroluminescent element comprising a plurality of electrode pairs facing each other and an electroluminescent layer disposed between the electrode pairs, and in which a plurality of portions of the electroluminescent layer sandwiched by the electrode pairs serve as light emitting regions. A manufacturing method comprising: a first electrode forming step of forming a plurality of band-shaped first electrodes on a substrate; and a plurality of island-shaped electroluminescent layers arranged side by side on and along the first electrode. An electric field characterized by comprising an electroluminescent layer forming step of forming a film, and a second electrode layer forming step of forming a plurality of band-shaped second electrodes on the electroluminescent layer so as to intersect with the first electrode. A method for manufacturing a light emitting element. (5) 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 electroluminescent layer forming step. Production method. (6) a first insulator layer forming step of forming a first insulating layer between the first electrode forming step and the electroluminescent layer forming step; 5. The method of manufacturing an electroluminescent device according to claim 4, further comprising a second insulating layer forming step of forming a second insulating layer between the layer forming step and the second insulating layer forming step.