JPH11265792A - EL device - Google Patents

Abstract

(57) [Problem] To provide an electroluminescent element in which the contrast at the time of non-light emission is reduced and the occurrence of a non-light-emission defective portion, short-circuit, insulation breakdown and the like are suppressed. SOLUTION: An anode electrode 12 is formed on a glass substrate 11, and a black mask film 13 is formed so as to cover the anode electrode 12. This black mask film 13
An organic EL layer 15 is formed in the opening 13C, and a cathode electrode 16 is formed to completely cover the organic EL layer 15. With such a configuration, the organic EL layer 15 is not exposed, and the anode electrode 12 / the organic EL layer 1 is not exposed.
5 and the interface between the cathode electrode 16 and the organic EL layer 15 can be prevented from entering moisture or oxygen. For this reason, deterioration of the organic EL layer 15 can be suppressed, and occurrence of non-light emission failure or short-circuit, insulation breakdown, and other defects can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent device using an organic luminescent material.

[0002]

2. Description of the Related Art In recent years, an organic electroluminescent device (hereinafter, referred to as an organic EL device) which is an electroluminescent device.
However, attention is being paid to realizing a DC low-voltage drive element, which has high visibility due to self-emission, is excellent in shock resistance because it is a solid element, and is a solid-state element.

Hereinafter, a conventional organic E will be described with reference to FIGS.
A typical manufacturing process of an L element will be described. First, for example, an ITO (indium tint) is formed on the glass substrate 1 over almost the entire surface.
a transparent conductive film of about 200 nm in thickness
The film is formed so that Then, the transparent conductive film is patterned by using the photolithography technique to form the anode electrode 2 as shown in FIG.

[0004] Next, as shown in FIG.
A rectangular organic EL layer 3 is formed so as to completely cover a predetermined portion (a portion to be a light emitting region) in the width direction. This organic E
In order to form the L layer 3, using a hard mask having a rectangular window, an organic hole transporting layer, an organic light emitting layer, and an organic electron transporting layer are sequentially formed using a vacuum evaporation apparatus in this order. ing.

[0005] Thereafter, as shown in FIG.
The cathode electrode 4 having a width smaller than the width dimension of, for example, a metal such as Mg-In is patterned by a vacuum evaporation apparatus using a hard mask.

The organic EL device 5 manufactured as described above
Means that the anode electrode 2 and the cathode electrode 4 are the organic EL layer 3
The structure is such that it does not directly contact via

[0007]

However, in the structure of the above-described electroluminescent element 5, there is a portion where the organic EL layer 3 is exposed. The interface with the EL layer 3,
At the interface between the cathode electrode 4 and the organic EL layer 3, oxidation, peeling, and crystallization progress, and there is a problem that a non-light emitting defective portion (dark area, dark spot, or the like) is easily generated locally.

[0010] Further, as shown in FIG. 10, the step coverage of the organic EL layer 3 is poor at the intersection of the anode electrode 2 and the cathode electrode 4 with respect to the step on the side wall of the anode electrode 2. Thickness of anode electrode 2
At the edge portion (shoulder portion), there is a problem that insulation breakdown due to short-circuit or overcurrent easily occurs between the anode electrode 2 and the cathode electrode 4.

Further, when displaying a character by the segment method, the anode electrode 2 and the cathode electrode 4 are used.
In addition, there has been a problem that structural measures have to be added to both of the electrodes, the degree of freedom of design is limited, and miniaturization is difficult.

Due to these problems, the conventional organic EL device 5 having the above-described structure has a long-term storage reliability (lifetime) as compared with an inorganic light emitting device (organic insulating film-dispersed inorganic EL device). It is low (short) and is an obstacle to practical application. In addition, since the anode electrode 2, the organic EL layer 3, and the cathode electrode 4 of the conventional organic EL element 5 are not dark, there is a problem that the contrast when light is not emitted is high.

The present invention has been made in view of such circumstances, and it is an object of the present invention to suppress the contrast at the time of non-light emission, to generate a non-light emission defective portion, short-circuit, insulation breakdown and the like. It is an object of the present invention to provide an electroluminescent device in which the occurrence of a defect is suppressed and the degree of freedom in design for displaying a character is improved.

[0012]

According to the first aspect of the present invention,
A first electrode having a predetermined pattern is formed on an insulating substrate, an EL layer is formed on the first electrode, and a second electrode is formed on the EL layer.
An electroluminescent element in which an electrode is formed and a region where the first electrode and the second electrode overlap with each other via the EL layer emits light, wherein the first electrode is located in a region on the upper surface of the first electrode. The EL layer is formed along the inner wall of the opening while being covered with a black insulating film having an opening formed therein, and the second electrode is formed so as to cover an exposed portion of the EL layer. It is characterized by having.

According to the first aspect of the present invention, since the opening formed in the black insulating film is located within the region of the upper surface of the first electrode, the region where the EL layer and the first electrode are in contact is defined. The area becomes a light emitting area. In addition, since the black insulating film other than the opening covers the first electrode, the black insulating film has an effect of preventing moisture and oxygen from entering the light emitting region of the EL layer from the first electrode side. Further, since the EL layer is covered with the second electrode, the EL layer has an effect of preventing moisture and oxygen from entering the interface between the second electrode and the EL layer. For this reason, the deterioration of the EL layer can be suppressed, and the occurrence of a non-light emitting defective portion can be suppressed.

According to a second aspect of the present invention, in the electroluminescent device of the first aspect, the black insulating film is formed of a photosensitive synthetic resin, and the opening is formed by exposure and development. It is characterized by:

According to the second aspect of the present invention, by forming the black insulating film with a synthetic resin, it is possible to use spin coating or another wet coating method at the time of forming the black insulating film, so that a flat insulating film can be formed. . For this reason, the insulation distance between the edge portion of the first electrode and the second electrode can be secured, and occurrence of defects such as short circuit and dielectric breakdown can be suppressed.

According to a third aspect of the present invention, in the electroluminescent device according to the first aspect, the black insulating film is formed by a printing method.

According to the third aspect of the present invention, since the black insulating film can be formed flat by the printing method, occurrence of defects such as short circuit and dielectric breakdown can be suppressed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the electroluminescent device according to the present invention will be described below with reference to the embodiments shown in FIGS. Prior to the description of the structure of the electroluminescent device, a manufacturing process of the electroluminescent device will be described.

First, as shown in FIG.
A transparent conductive film made of ITO having a thickness of about 200 nm is formed thereon, and an anode electrode 12 as a first electrode is formed in a desired pattern by using a photolithography technique.
In this embodiment, for convenience of explanation, an example having two anode electrodes 2 will be described.

Thereafter, as shown in FIG. 2, an insulating film made of a pigment-based or dye-based photosensitive resin material such as carbon black is formed on substantially the entire surface of the glass substrate 11 on which the anode electrode 12 is formed. The thickness of the black mask film 13 is set to 0.5 to 0.5 by spin coating or printing.
It is formed to have a thickness of 1.5 μm. Black mask film 1
Reference numeral 3 denotes black, which is opaque to a wavelength range in which the organic EL layer 15 emits light, which will be described later.

Next, a process for forming the organic EL layer 15 will be described with reference to FIGS. 3 (a) to 3 (c) and FIG. 3 (a) to 3 (c) show portions corresponding to the AA cross section in FIG.

First, as shown in FIG. 3A, a photomask 14 having a predetermined pattern is arranged above the black mask film 13 formed in the above-described steps, and exposure is performed. In the figure, reference numerals 13A and 13B indicate exposed portions of the black mask film 13. Thereafter, as shown in FIG. 3B, development is performed to remove the exposed portions 13A and 13B. In this way, as shown in the figure, a concave portion 13C for embedding an organic EL layer 15 to be described later, in which the anode electrode 12 is exposed, and a terminal portion 12A are formed. Then, as shown in FIG. 3C, the organic EL layer 15 is formed along the inner wall of the recess 13C. The organic EL layer 15 is formed so as to cover the periphery of the opening of the recess 13C. The organic EL layer 15 is formed by using a metal hard mask (not shown) having an opening slightly larger than the planar contour of the recess 13C, and sequentially using an organic hole transport layer, an organic light emitting layer, and an organic light emitting layer. An electron transport layer (all layers are not shown) is formed by continuous film formation using a vacuum evaporation apparatus.

The organic hole transporting layer has the following structural formula

Embedded image N, N'-di (α-naphthyl) -N, N'-diphenyl-
It is formed of 1,1'-biphenyl-4,4'-diamine (hereinafter referred to as α-NPD).

The organic light emitting layer has the following structural formula

Embedded image 4,4′-bis (2,2′-diphenylvinylene) biphenyl (hereinafter referred to as DPVBi) represented by the formula:

Embedded image And 4,4′-bis (2-carbazolevinylene) biphenyl (hereinafter, referred to as BCzVBi) by co-evaporation with 4 wt%.

Further, the organic electron transporting layer has the following structural formula

Embedded image Of tris (8-hydroxyquinoline) aluminum (hereinafter referred to as Alq3). Incidentally, the total thickness of the organic EL layer 15 is set to about 100 nm.
FIG. 4 is a plan view showing a state where the organic EL layer 15 is formed.

After forming the organic EL layer 15 as described above, as shown in FIG. 5, a cathode electrode 15 having a width longer than the width of the organic EL layer 15 is formed so as to intersect with the anode electrode 12. The organic EL layer 15 is completely covered. In addition, as a method for forming the cathode electrode 15, for example, a metal such as Mg—In is vacuum-evacuated using a metal hard mask (not shown) in which an opening pattern having a width longer than the width of the organic EL layer 15 is formed. A film is formed by a vapor deposition device. Thus, the manufacture of the electroluminescent device 17 is completed. Note that a protective film may be appropriately formed to cover the element surface as needed.

Next, the structure of the electroluminescent device 17 of the present embodiment manufactured as described above will be described with reference to FIGS. FIG. 6 is a sectional view taken along line BB of FIG. As shown in FIG. 5 and FIG. 6, the electroluminescent element 17 of the present embodiment includes a portion of the anode electrode 12 patterned on the glass substrate 11 corresponding to the light emitting region and the terminal portion 12A.
The other parts are completely covered with the black mask film 13. Also, the concave portion 1 formed in the black mask film 13
The organic EL layer 15 formed so as to cover 3C is completely covered with the cathode electrode 16. And
The portion of the organic EL layer 15 sandwiched between the anode electrode 12 and the cathode electrode 16 becomes a light emitting region.

With such a configuration, in the electroluminescent device 17 of this embodiment, the organic EL layer 15 is formed by the anode electrode 12, the black mask film 13, and the cathode electrode 16
Therefore, the organic EL layer 15 is not directly exposed to the outside air. For this reason, the organic EL layer 15 is hardly affected by moisture or oxygen, and it is possible to suppress the occurrence of non-light emission failure (dark area, dark spot, etc.) locally.

In the electroluminescent device 17 of this embodiment, since the edge of the anode electrode 12 is covered with the black mask film 13, a short circuit between the anode electrode 12 and the cathode electrode 16 or a dielectric breakdown due to an overcurrent occurs. The effect is that it is difficult to occur.

Further, in the patterning step of the black mask film 13, the black mask film 13 is arranged in a region other than the light emitting region of the organic EL layer 15 and the terminal portion 12 A of the anode electrode 12, so that reflected light other than the light emitting region can be reduced. Since transmitted light is suppressed, an electroluminescent element having good visibility (contrast) is obtained.

Further, in the case of performing the character display by the segment method, the character shape can be patterned in the patterning step of the black mask film 13, and the degree of freedom in designing the anode electrode 12 and the cathode electrode 15 can be increased. is there.

Although the embodiment has been described above, the present invention is not limited to this, and various changes accompanying the gist of the configuration are possible. For example, in the embodiment described above, the anode electrode 12 is formed on the glass substrate 11 and the cathode electrode 16 is formed on the organic EL layer 15, but the anode electrode 12 and the cathode electrode 16 may be replaced. In this case, the substrate need not be a transparent substrate such as the glass substrate 11.

In the above-described embodiment, the black mask film 13 is patterned by exposing and developing the black mask film 13 using a photosensitive material. Of course, the black mask film 13 may be formed in a pattern that exposes the concave portion 13C and the terminal portion of the anode electrode 12 by a printing method.

Further, in the above embodiment, the organic EL
The layer 15 is formed by stacking three layers of an organic hole transport layer, an organic light emitting layer, and an organic electron transport layer, that is, the organic hole transport layer is formed of α-N
Formed with PD and organic light emitting layer is DPVBi (96 wt%)
And BCzVBi are formed by co-evaporation of (4 wt%)
Although the organic electron transporting layer is formed of Alq3, the organic electron transporting layer is not limited to this as long as it is an organic film that emits light by the recombination of holes and electrons substantially with carrier injection. For example, an organic hole transport layer made of α-NPD is formed on the anode electrode 12 and the following structural formula is formed on the organic hole transport layer.

Embedded image As an organic EL layer 15 having a two-layer structure in which organic layers having a function of both a light emitting layer and an electron transport layer are formed of beryllium bis (10-hydroxybenzo [h] quinoline) represented by the following formula: Is also good. In the above-described embodiment, the simple matrix structure is used. However, the anode electrode 12 is divided for each pixel, and X
A selection thin film transistor connected to a gate line and a drain line extending in the -Y direction, a driving transistor having its gate electrode connected to the source electrode of the selection transistor, and one of its source and drain electrodes connected to the anode electrode 12 And an active drive circuit consisting of
It may be provided below the black mask film 13.

[0035]

As is apparent from the above description, according to the present invention, the electric field in which the contrast during non-light emission is suppressed to a low level and the occurrence of non-light-emission defective portions, short-circuit, insulation breakdown and other defects is suppressed. There is an effect of realizing a light emitting element. Further, according to the present invention, there is an effect that the degree of freedom of design is improved when displaying characters.

[Brief description of the drawings]

FIG. 1 is a process plan view showing a manufacturing process of an embodiment of an electroluminescent device according to the present invention.

FIG. 2 is a process plan view showing a manufacturing process of the embodiment.

3 (a) to 3 (c) are process cross-sectional views showing a manufacturing process in an AA cross section in FIG. 2;

FIG. 4 is a process plan view showing a manufacturing process of the embodiment.

FIG. 5 is a process plan view showing a manufacturing process of the embodiment.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 is a process plan view showing a manufacturing process of a conventional electroluminescent element.

FIG. 8 is a process plan view showing a manufacturing process of a conventional electroluminescent element.

FIG. 9 is a process plan view showing a manufacturing process of a conventional electroluminescent device.

FIG. 10 is a sectional view taken along line CC of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Anode electrode 13 Black mask film 13C Depression 15 Organic EL layer 16 Cathode electrode 17 Electroluminescent element

Claims (3)

[Claims] A first electrode having a predetermined pattern formed on an insulating substrate; an organic electroluminescent layer formed on the first electrode; a second electrode formed on the electroluminescent layer; An electroluminescent device in which a region where one electrode and the second electrode overlap with each other via the electroluminescent layer emits light, wherein the first electrode has an opening formed in a region on an upper surface of the first electrode. The electroluminescent layer is formed along the inner wall of the opening, and the second electrode is formed so as to cover an exposed portion of the electroluminescent layer. An electroluminescent element characterized by the following. 2. The electroluminescent device according to claim 1, wherein the black mask insulating film is formed of a photosensitive synthetic resin, and the opening is formed by exposure and development. 3. The electroluminescent device according to claim 1, wherein the black mask insulating film is formed by a printing method.