JPH02148597A - El device and el display using same - Google Patents

Abstract

PURPOSE:To obtain high quality EL device and EL display by providing a compound layer of water repellency between a second insulating layer and a second electrode, whereby deterioration of a luminous layer due to moisture can perfectly be prevented. CONSTITUTION:After a transparent first electrode 2 is formed on a glass substrate 1 by RF sputtering, a first insulating layer 3 is formed thereon. Then a luminous layer 4 is formed thereon by electron beam vapor deposition, and a second insulating layer 5 is formed on the layer 4. A polymeric compound of water repellency is formed thereon as a compound layer 6 by RF sputtering, and then, metal Al is formed as a second electrode 7 by resistance heating vapor deposition. By forming the compound layer 6 of water repellency on the second insulating layer 5, even though there is a defect such as a pin hall that penetrates the layer 5, moisture does not permeates, and deterioration of the luminous layer 4 due to moisture during the patterning of the electrode 7 can thus be prevented.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides an electronic device capable of displaying multiple colors and having excellent display quality.
The present invention relates to an L element and an EL display using the EL element.

[Conventional technology]

Conventional EL elements have In, O, and Sn on a glass substrate.
A transparent first layer called ITO, which consists of O and O? ! ! A pole is formed to a thickness of about 0.2 μm, and on top of this a first insulating layer made of a metal oxide, a light-emitting layer made of a matrix such as ZnS and containing a small amount of light-emitting centers such as Mn, and a second layer made of a metal oxide. The two green layers are stacked in this order from the bottom. The thickness of each of these layers is approximately 0.2 to 0.5 μm for the first and second anti-green layers, and approximately 0.4 to 1.2 μm for the light emitting layer. A second electrode made of metal AQ is formed on the second anti-green layer to a thickness of 0.2 to 0.3 μm. The first electrode and the second electrode are formed in stripes so as to be perpendicular to each other.

Therefore, by applying a scanning pulse to one electrode row and applying a signal pulse to the other electrode row, a voltage pulse higher than the light emission threshold voltage can be applied to any part of the electrode claw (
Since the voltage can be applied to each pixel (pixel), it is possible to display a single character, figure, etc.

In the ELi device having such a structure, the first electrode and the second electrode are formed by a photo-etching process. That is, the laminated portion of the insulating layer and the light emitting layer is immersed in various chemicals containing moisture, such as an etching solution and an organic solvent. For this reason, if there is a defect in the second green-proofing layer that penetrates the film, such as a pinhole, chemicals, especially moisture, may penetrate into the defective part, which may deteriorate the light-emitting characteristics or the liquid-proofing properties of the EL element. .

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 58-85295, a method called a foot-off method has been proposed to prevent the surface of the second green layer from coming into contact with moisture as much as possible.

Furthermore, as shown in Japanese Patent Publication No. 54-39716, a method has been proposed in which the second anti-green layer is made into a two-type structure to suppress the formation of defects penetrating the film such as pinholes.

Furthermore, a method is known in which a small amount of moisture that has penetrated is removed by a vacuum degassing process after forming the second electrode.

Based on the various methods described above, the light-emitting JW is ZnS:M
A monochrome EL display of n (base ZnS, luminescent center M n , yellow-orange luminescence) has already been put into practical use. However, since monochrome EL displays have a limited amount of display information, there is a strong desire to realize multicolor EL displays.

Based on this requirement, CaS, SrS
Materials using alkaline earth sulfides as a matrix and adding rare earth elements to them have been studied. As a result, red, blue,
A white, high-luminance emissive layer was found. All colors,
In terms of brightness, it has light-emitting characteristics that cannot be obtained with a light-emitting layer using ZnS as a matrix.

Therefore, it is necessary to fabricate a light emitting layer containing SrS or CaS as a device.

[Problem to be solved by the invention]

However, in order to form a device, the second electrode must be patterned, but no matter what method is used in the above-mentioned conventional technology, in particular, the light-emitting layer has an alkaline earth sulfide as a base material and a rare earth element or a rare earth element. When a halide, sulfide, or phosphide is included as a luminescent center,
It is not possible to properly pattern the second electrode. Namely.

In the lift-off method, the light-emitting layer deteriorates due to a small amount of moisture contained in the organic solvent used when removing the resist. Furthermore, in the method in which the second anti-green layer has a double structure, it is impossible to completely eliminate pinholes, and as a result, water permeates through the pinholes. Furthermore, the method of vacuum degassing is less effective because once moisture penetrates into the luminescent layer, the luminescent layer deteriorates in an instant.

An object of the present invention is to create an E with a structure that can completely prevent moisture from penetrating into one light-emitting layer when patterning a second electrode.
An object of the present invention is to provide an L element and an EL display using the EL element.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a first insulating layer, a light emitting layer, and a second insulating layer to cover the first electrode. are laminated in this order from the bottom, and a linear second electrode is further provided on the second anti-green layer, and a water-repellent layer is provided between the second anti-green layer and the second electrode It is equipped with a compound layer.

Further, in the present invention, a linear first electrode is disposed on an insulating substrate, and an eighth insulating layer is provided so as to cover the first electrode.

In an EL element in which a light emitting layer and a second constant green layer are laminated in this order from the bottom, and a linear second electrode is further disposed on the second constant green layer, the second electrode is made of a transparent material. , having a water-repellent compound layer between the second M calendar and the second electrode,
Further, a color filter is provided on the second electrode.

Furthermore, the present invention provides an EL display in which characters and figures are displayed on a screen by arbitrarily selecting a large number of pixels to emit light. A perturbation circuit for applying 25'2 is connected.

[Effect]

According to the above structure, if a water-repellent compound layer is formed on the second anti-green layer, moisture will not penetrate even if there is a defect such as a pinhole penetrating the second anti-green layer. When patterning the second electrode, it is possible to prevent the light emitting layer from deteriorating due to moisture.

By the way, alkaline earth sulfide (Ca
(S, SrS, BaS, etc.) forms an interface with the insulating layer, and from the deep level of this interface or the trap level created within the band gap in the supra-alkali sulfide, electrons are moved by the electric field to the conduction band of the light-emitting layer matrix. These electrons are further accelerated by the electric field and become hot electrons.

The hot electrons directly impact and excite the luminescent center or ionize the luminescent layer matrix, and when the generated electron-hole pairs recombine, energy is transmitted to the luminescent center and excites the luminescent center. Energy level difference in 4f electron orbit in rare earth ion (4f-5d in case of Ce"Eu"+
It shows EL emission with a constant wavelength determined by the level (between levels).

For example, in the case of CaS:Eu (CaS is the host, Eu is the luminescence center), red luminescence with a peak at about 650 nm, Sr.
In the case of S:Ce, it has a peak at about 490 nm and is 450 to 6
Blue-green emission spread over 00 nm, 49 for SrS:Pr
It emits white light (because the two peaks are complementary colors) with two sharp peaks at 0 nm and 660 nm.

As mentioned above, these light-emitting layers exhibit a color tone and brightness that cannot be obtained with a light-emitting layer based on ZnS, but they are also resistant to extremely small amounts of water that permeate through the second green layer when forming the second electrode. A deterioration phenomenon (mainly a decrease in brightness) occurs. The present invention improves this drawback.

〔Example〕

The present invention will be explained in detail below.

(Example 1) When the contact angles of various substances with water were investigated, it was found that the contact angles of polymer compounds were large.

An example of the contact angle determined is shown below.

For comparison, S i 02. is an inorganic compound. S1
JN4゜AQ20. A thin film of Ta205 was formed on a glass plate by RF sputtering, and the contact angle with water was examined, and it was found to be as small as 20 to 50 degrees.

Next, an EL element having the structure shown in FIG. 1 was manufactured using each of the above materials. Cornin of 34m0 is used for glass substrate 1.
g 7059 was used. On top of this, a transparent first electrode 2 (ITO) was formed to a thickness of 0.2 μm by RF sputtering, and then 3 μm was formed by a photoetching process.
A live pattern was formed with a resolution of 1/frn. After cleaning this surface thoroughly.

Ta,
05 film was formed to a thickness of 0.4 μm. Next, a light emitting layer M4 was formed thereon using an electron beam evaporation method. Luminous layer 4
The material used is SrS as a matrix, and Ce is added to it.
Q, to which 0.1 moQ% was added was used. Sr.
After mixing S and CeCQ in a predetermined amount, the mixture was compacted into a tablet shape and used as a raw material for evaporation. Before evaporation, the raw material was sufficiently degassed, and the degree of vacuum in the evaporation tank was made sufficiently high. Set the board temperature to 50
The light emitting layer 4 was formed to have a thickness of 1.0 μm at 0° C.

On this light-emitting layer 4, a second anti-green layer 5 of Ta, 05
A laminated film was formed with a thickness of 0.4 μm and a thickness of 0.17 zm. The light-emitting layer 4 side is Ta, ◯. On this, one of the eight types of polymer compounds described above was formed as the compound layer 6 by RF sputtering. For comparison, an element in which no polymer compound was formed and an element in which ΔQ20° was formed with a thickness of 0.1 μm instead of 5 in 2 were also fabricated.

Thereafter, metal AQ was formed as a second electrode 7 to a thickness of 0.2 μm by resistance heating vapor deposition. This AQ film was processed by a photoetching process into a stripe shape with a precision of 3 lines per stripe so as to be orthogonal to the ITO pattern. A.R.
The etching solution is an acidic aqueous solution (by volume, phosphoric acid:
Acetic acid:nitric acid:water=75:15:5:5) was used.

Next, the state of the light emitting WJ4 of the EL element produced by the above-described method was observed using an optical microscope. When the etching solution penetrates through the second green-proofing layer 5 or the laminated film of the second green-proofing layer 5 and the compound layer 6 and reaches the light-emitting layer 4,
Under a microscope, ml FX is mainly seen as black spots. Note that the element in which the compound layer 6 is not formed, that is, the second anti-green layer 5 is made of SiO2/Ta2O and AQZO3/T
a20. In an element having a structure in which the surface is in direct contact with the etching solution, it was found that the light-emitting layer 4 was attacked and deteriorated by visual observation, not to mention microscopic R observation.

The microscopic MK observation results are summarized below. The luminescent WJ4 was evaluated by marking 0 on those in which no defects caused by deterioration, that is, black spots were observed, Δ on those on which some spots were observed, and X on those on which a large number of spots were observed.

For those evaluated as O, the luminescence characteristics were examined by applying a voltage. As a result, good light emitting characteristics (Q1 degree, spectrum) were obtained for all devices.7 In other words, the characteristics are no different from those of devices in which the second electrode 7 was formed without using a photoetching process (resistance heating mask evaporation). Met.

(Example 2) Next, another example of the present invention is shown in FIG. The difference between this embodiment and the one shown in FIG. , III
o Add Q% each to emit white light F! Forming J4 and the second? I! This is because color filters of three primary colors are formed on the pole 7. Since SrS:Pr and Ce emit white light, multicolor display is possible by using a color filter.

The manufacturing method is almost the same as in Example 1, so it will be briefly explained.

A 50 an 0 glass substrate 1 on which ITO was formed was used.

As the first electrode 2', ITO was patterned to a precision of 8 lines/m (electrode width 100 μm, electrode spacing 25 μm).

On this layer, a laminated film of Ta was formed as the first insulating layer 3, SrS:Pr and Ce was formed as the light emitting layer 4', and a laminated film of SiO2 and Ta2O was formed as the second anti-green layer 5, respectively. S I Oz +Ta, O, was formed by RF sputtering method, and SrS:Pr, Ce was formed by electron beam evaporation method.

Polytetrafluoroethylene was formed thereon as a compound layer 6 by RF sputtering.

Furthermore, ITO was formed as a second electrode 7' on this by RF sputtering. Next, this ITO was patterned to a precision of 3 lines/nn using a photoetching process. Hydrogen bromide is used as an etching solution for ITO.
(HBr) aqueous solution was used. A glass substrate 1' on which color filters 8 are formed in a red, green, and blue stripe pattern with a resolution of 8 filters/rrm is provided on the EL element manufactured as described above, and a pattern of the first electrode 2' is formed. After alignment, the periphery of the glass substrate 1' was covered with resin in a dry N277 atmosphere. This prevents moisture from entering the EL element and suppresses deterioration of the EL element during driving.

Terminals were drawn out from the first electrode 2' and the second electrode 7' and connected to a drive circuit to examine the characteristics as an EL display. As a result, it was confirmed that multi-color display with a color reproduction range quite close to that of a color CRT was possible. FIG. 3 shows the obtained three primary color tones using a CIE chromaticity diagram. , indicates the three primary colors of a color CRT. In addition, the three primary colors 0N-O
Eight-color display and text display using FF were also confirmed.

Note that in Examples 1 and 2, the light emitting layer was formed by electron beam evaporation, but it can also be formed by RF sputtering or CVD. Furthermore, it can also be formed by applying a compound layer by a pulling method or a spin code method and then drying and solidifying it.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to completely prevent the luminescent layer from deteriorating due to moisture, so that high-quality EL
elements and EL displays can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an EL device according to the present invention, FIG. 2 is a cross-sectional view of an EL device in another embodiment, and FIG. 3 is a CIE chromaticity diagram showing the color tones of the three primary colors in the EL display of the present invention. be. 1.1'...Glass substrate, 2,2'...First electrode. 3... First insulating layer, 4.4'... Light emitting layer, 5... Second constant green layer, 6... Compound layer, 7,7'... Second electrode,
8...Color filter.

Claims (8)

[Claims] 1. A linear first electrode is disposed on an insulating substrate, a first insulating layer, a light-emitting layer, and a second anti-green layer are laminated in this order from below so as to cover the first electrode, and further the second insulating layer An EL element having a linear second electrode disposed thereon, further comprising a water-repellent compound layer between the second anti-green layer and the second electrode. 2. 2. The EL device according to claim 1, wherein the compound layer is made of a polymeric material having a contact angle with water of 80 degrees or more. 3. 3. The EL device according to claim 1, wherein the compound layer is polytetrafluoroethylene. 4. 2. The EL device according to claim 1, wherein the light emitting layer has an alkaline earth sulfide as a matrix and contains a rare earth element or a halide, sulfide, or phosphide of a rare earth element as a light emitting center. . 5. 5. The EL device according to claim 4, wherein the alkaline earth sulfide is any one of SrS, CaS, and BaS, or a solid solution of two or more of these. 6. 5. The EL device according to claim 4, wherein the rare earth elements include Ce, Pr, Sm, Eu, Tb, Dy, Ho, and E.
An EL device characterized by being at least one of r and Tm. 7. A linear first electrode is disposed on an insulating substrate, a first insulating layer, a light-emitting layer, and a second anti-green layer are laminated in this order from below so as to cover the first electrode, and further the second insulating layer In an EL element having a linear second electrode disposed thereon, the second electrode is made of a transparent material, and has a water-repellent compound layer between the second insulating layer and the second electrode, An EL element comprising a color filter on the second electrode. 8. In an EL display that displays characters or figures on a screen by arbitrarily selecting a large number of pixels to emit light, a voltage pulse is applied to the first electrode and the second electrode of the EL element according to claim 1 or 7. An EL display characterized by having a drive circuit connected thereto.