JPH09274991A - Multicolor electroluminescent device - Google Patents

Abstract

(57) Abstract: A multicolor light emitting electroluminescent device having high brightness and low cost is provided. At least an overlapping portion of a color filter 5 and an element portion formed by laminating a first electrode 21, a first insulating layer 31, a phosphor layer, a second insulating layer 32, and a second electrode 22. In the multicolor light emitting EL device, which has the superposed portion and emits the light transmitted through the color filter to the outside, one of the superposed portions is an element portion having a phosphor layer 4rg made of ZnS: Mn and a red filter 5r. The other one of the superposed parts is a combination of an element part having a phosphor layer made of ZnS: Mn and a green filter 5g, and a blue element part is SrS:
It is supposed to have a phosphor layer 4b made of Ce. Reference numeral 11 is a first substrate, 12 is a second substrate, and 6 is silicone oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electroluminescence device used for a color display or the like, and more particularly to a multicolor light emission electroluminescence device exhibiting different emission colors.

[0002]

2. Description of the Related Art A thin film electroluminescence (hereinafter abbreviated as EL) display device as one of flat display devices is sharp and has a high contrast ratio.
Since the viewing angle dependence is also small, research and development are being conducted as FA display devices, vehicle-mounted display devices, and computer terminal display devices. Although a monochrome thin film EL display using a phosphor composed of yellow-orange emitting ZnS: Mn has already been put into practical use, colorization is becoming indispensable as the display is diversified.

Color thin film EL using inorganic phosphor thin film
There are the following two typical methods for realizing the device. One is RGB independent light emission method (RG
B represents red, green and blue) and the other 1
One is the color filter method. FIG. 5 is a cross-sectional view of a conventional RGB independent light emitting color thin film EL device. This method is characterized in that the light emitting layer is patterned for each color of light emission. On the first glass substrate 11, a first electrode 21 made of a transparent conductive material (hereinafter referred to as TCO) in a stripe shape (the stripe direction is parallel to the paper surface), a first insulating layer 31 covering the whole, Stripe patterns alternately arranged and patterned (the direction of the stripes is perpendicular to the paper surface) are individually covered with three types of phosphor layers 4r, 4g, and 4b that respectively emit red, green, and blue light. The second insulating layer 32 and the stripe-shaped second electrode 22 are sequentially formed on the respective phosphor layers. The first glass substrate and the second glass substrate 12 are fixed via a sealing member 7, and the space between the substrates is filled with moisture-proof silicone oil 6 to form an EL device.

Any of the phosphor layers 4r, 4g, 4b is sandwiched between the intersections of the first electrode 21 and the second electrode 22 to form a pixel, and the entire pixel forms a matrix. . From each pixel, each monochromatic light R (red), G (green), B
(Blue) is emitted outside the EL device. Figure 6 shows the conventional RG
It is sectional drawing of the other color thin film EL display of B independent light emission system. On the first glass substrate 11, a red light emitting phosphor layer 4r and a green light emitting phosphor layer 4g overlapping with the red filter 5r are arranged. On the second glass substrate 12, a phosphor layer 4gb that emits blue-green light is formed.
Similar to the above example, two glass substrates are assembled into an EL device.

In this structure, red light is transmitted from the red-emitting phosphor layer 4r through the red filter 5r, blue light is transmitted directly from the phosphor layer 4gb, and green light is transmitted from the phosphor layer 4gb through the green filter 5g. It is emitted to the outside. In any of the above cases, as the phosphor layer 4r, ZnS: Sm or CaS: Eu,
ZnS: Tb and CaS: Ce are used as the phosphor layer 4g, and ZnS: Tm and SrS: Ce are used as the phosphor layer 4b (Japanese Patent Laid-Open No. 61-
560594 and Japanese Unexamined Patent Publication (Kokai) No. 5-65478), and SrGa ₂ O ₄ : Ce (Japanese Unexamined Patent Publication (Kokai) No.
No. 65478) is used, and the patterning process is required once for each phosphor layer, that is, three times in total.

FIG. 7 is a cross-sectional view of a conventional color filter type color thin film EL display. In this method, white light emitted from the light emitting layer is divided into three primary colors by a color filter. The phosphor layer of the first glass substrate 11 is
It is a stack of a first phosphor layer 4rg that emits red and green light and a second phosphor layer 4gb that emits blue and green light. Striped color filters of red, green, and blue are patterned on the second glass substrate so as to overlap the second electrode 22 of the first substrate.

ZnS: M as a light emitting material having red and green components
It has been proposed to use SrS: Ce as a light emitting material having n, blue and green components (Japanese Patent Laid-Open No. 62-74896).

[0008]

However, there are some problems in realizing the structure of the color EL display described above, and there is still no example in which it has been put to practical use. The problems will be described below. First, in the RGB independent light emission method that does not use a color filter, Sr, which has a good color purity recently,
Although a blue phosphor such as Ga ₂ O ₄ : Ce has been developed and is being improved in terms of color purity, three patterning steps are required because it is necessary to separately form three types of light emitting layers of RGB.
The process also becomes long and the yield decreases, which causes a cost increase. Also, a method of dividing into two substrates (Fig. 6)
Then, although the number of times of patterning the light emitting layer is the same, the cost is further increased because two substrates are required.

The color filter method is being studied for practical use, but the decrease in luminance due to the filter is large,
In order to obtain practical brightness, improvement of the brightness of the white light emitting layer is an issue. Regarding the current luminous efficiency, there is a method of further increasing the film thickness to improve the brightness, but it is considered that it is quite difficult to solve the problem by the film thickness because the voltage on the driving IC side is limited.

The present invention has been made in view of the above problems, and an object thereof is to provide a multicolor light emitting EL device having high brightness and low cost.

[0011]

In order to achieve the above object, an element portion in which a first electrode, a first insulating layer, a phosphor layer, a second insulating layer and a second electrode are laminated. And a color filter at least, and in the multicolor light emitting EL device which emits the light transmitted through the color filter to the outside from the superposition part, one of the superposition parts is a phosphor layer made of ZnS: Mn. Is a combination of an element unit having a red filter, and the other one of the overlapping portions is a combination of an element unit having a phosphor layer made of ZnS: Mn and a green filter,
The blue element portion has a phosphor layer made of SrS: Ce.

Alternatively, it has at least an overlapping portion of a color filter and an element portion formed by laminating a first electrode, a first insulating layer, a phosphor layer, a second insulating layer and a second electrode, In the multi-color light emitting EL device which emits the light transmitted through the color filter to the outside from the superimposing section, one of the superimposing sections is a combination of an element section having a phosphor layer made of ZnS: Mn and a red filter, The other one of the overlapping parts is Zn
S: is a combination of a green filter and an element unit having a phosphor layer made of Mn and a phosphor layer made of SrS: Ce,
The blue element portion has a phosphor layer made of SrS: Ce.

A combination of a blue filter with the blue element portion may be used as one of superimposing portions. Further, it is preferable that the first substrate on which the overlapping portion is formed and the second substrate made of glass on which the color filter is formed face each other and are assembled to each other.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The basic structure of a multicolor light emitting EL device according to the present invention is: a first electrode, a first insulating layer, a phosphor layer that simultaneously emits red light and green light, and a second insulating layer. And the second
It has an overlapping portion of a color filter and an element portion in which the electrodes of (1) are laminated, and individual red filters and green filters are combined in this overlapping portion. On the other hand, the phosphor layer of the element portion of the blue light emitting portion is made of blue light emission, and there are cases where a blue filter is combined to form a superposed portion and cases where a blue filter is not combined.

The red light emitting part phosphor layer is a ZnS: Mn single layer, and the green light emitting part phosphor layer is a ZnS: Mn single layer and a ZnS: Mn single layer.
And SrS: Ce may be laminated. The phosphor layer of the blue light emitting part
It is a single layer of SrS: Ce. The first electrode and the second electrode of the element part are most simply a number of stripes orthogonal to each other,
The portion where each one intersects is one pixel. The phosphor layer and the filter corresponding to one color are superimposed on at least each pixel. It is necessary to use a transparent conductive material such as indium tin oxide for the electrode on the side of the phosphor layer that transmits light emission.

Since the element portion and the filter are thin films and cannot maintain the shape independently, they are formed on the substrate. The substrate is a glass substrate for transmitting light when external light is emitted through the substrate. On the other side, it may be ceramics, metal, or resin, but it is necessary to assemble the substrate on the light emitting side so that it is not preferable to use a material having a different coefficient of thermal expansion. Substrate is suitable.

The element portion is formed in the following order. The first electrode is formed on the glass substrate by film formation and patterning, and the whole is covered with the first insulating layer. Next, one of the ZnS: Mn phosphor layer and the SrS: Ce phosphor layer is formed and patterned first, and then another phosphor layer is formed and patterned, if necessary. Accordingly, the phosphor layer forms a laminated portion. Further, the whole is covered with a second insulating layer, and finally a second electrode is formed by film formation and patterning. In any case, the phosphor layer is patterned twice.

The color filter can be directly formed on the element part, and there is no gap between the filter and the element part, and high optical efficiency can be expected, but it is better to form the color filter on another substrate in consideration of the yield. It will be advantageous. In any case, the filter is formed by film formation and patterning of the filter material. As the color filter material, in addition to the pigment dispersion type organic material filter, a dye type filter or an interference filter can be applied.

The element portion mounting substrate thus manufactured has its periphery fixed to another substrate via a sealing member, and silicone oil is sealed in the space between the substrates to seal the multi-color light emission. The EL device is completed. Further, the multicolor light emitting EL device according to the present invention includes a thin film type, a dispersion type, or an AC type,
Any DC type drive system can be applied.

The operation of each superimposing portion of the multicolor light emitting EL device according to the present invention will be described below. The ZnS phosphor, which uses divalent Mn ion as a luminescent impurity, has a very high luminous efficiency of 2 to 8 lm / W, and has a broad emission spectrum centered at 580 nm in the emission spectrum, so it passes through the red and green filters. By doing so, red emission and green emission with good color purity can be obtained.

Since the SrS phosphor containing trivalent Ce ions as an impurity emits a broad blue-green light having a center wavelength of 490 nm, it is possible to obtain blue light suitable for multicolor emission without passing through a blue filter. Can be used. But Sr
By using the blue-green light emission of S: Ce after passing through the blue filter, it is possible to improve the color purity of blue by removing the green light and make it suitable for a full-color image.

Further, since the green light emitted from the ZnS: Mn phosphor that has passed through the green filter is green with a chromaticity that is slightly close to red, ZnS: Mn and SrS: Ce are laminated only in the green light emitting pixel portion. By using the emitted light from the phosphor layer, the green light can be increased and the color purity can be improved. Example 1 FIG. 1 is a sectional view of a multicolor light emitting EL device of an example according to the present invention. A 200 nm-thick tungsten thin film was formed on the glass substrate 11 by sputtering, and a stripe-shaped first electrode 21 was formed by photolithography and dry etching. The longitudinal direction of the stripe is parallel to the paper surface of FIG. The entire surface is covered with SiO ₂ and Si ₃ N ₄ by high frequency sputtering.
The laminated film of 200 nm was formed to be the first insulating layer 31.

A phosphor layer made of ZnS: Mn having a thickness of 700 nm is formed on the first insulating layer 31 by electron beam heating vapor deposition, and is patterned in stripes by photolithography and dry etching to simultaneously perform red and green. Phosphor layer 4 that emits light
rg was formed. A second phosphor layer 5 made of SrS: Ce is further formed thereon by the same electron beam heating vapor deposition to a thickness of 1000 nm, and is patterned into stripes by photolithography and dry etching, and the blue phosphor layer 4b is formed. Was formed. After that, heat treatment was performed at 600 ° C for 30 minutes in an H ₂ S atmosphere. The stripe direction of these phosphor layers is perpendicular to the stripe direction of the first electrode.

A laminated film of SiO ₂ and Si ₃ N ₄ having a thickness of 200 nm was formed on the phosphor layers 4rg and 4b by high frequency sputtering to form a second insulating layer 32. Finally, an indium tin oxide (ITO) thin film is formed as a transparent conductive layer, and the second stripe-shaped second layer is formed by photolithography and dry etching.
The electrode 22 of was formed. This stripe is aligned with that of the phosphor layer.

On the second glass substrate 12, a stripe-shaped filter whose shape matches the stripe of the phosphor layer was formed. In this embodiment, the filters 5r and 5g made of a pigment dispersion type organic material that transmits red and green are Zn.
It was arranged corresponding to the phosphor layer 4rg made of S: Mn. SrS:
The blue-green light emitted from the phosphor layer 4gb made of Ce is directly used without passing through the blue filter.

The first substrate 11 on which the phosphor layer is formed and the second substrate 12 on which the filter is formed are fixed to face each other via the sealing member 7, and silicone oil is filled in the space between the substrates. Filled and completely sealed, multi-colored EL
The device. In the multicolor light emitting EL device of the present invention, by applying an AC voltage between the striped lower metal electrode 2 and the striped upper transparent electrode 7, the phosphor layer at the intersection of these can be made to emit light. By transmitting the respective color filters, the red light and the green light can be emitted independently of the three primary colors of the blue-green light from the portion without the color filter, so that a color image can be displayed. Example 2 FIG. 2 is a sectional view of a multicolor light emitting EL device of another example according to the present invention. In this example, the structure of the phosphor layer of the first substrate 11 and the like were the same as in the first example. Further, on the second substrate 12, a blue filter 5b is additionally formed between the red and green filters having the same structure as in the first embodiment so as to overlap the phosphor layer 4b made of SrS: Ce. Each substrate was assembled into a multicolor light emitting EL device in the same manner as in Example 1.

With the structure of this embodiment, a color image can be displayed as in the first embodiment, and since the green component is removed by the blue filter, the blue color purity of the display image is improved. It was This multicolor light emitting EL device is suitable for displaying a full-color image. Example 3 FIG. 3 is a sectional view of a multicolor light emitting EL device according to another example of the present invention.

This embodiment has a similar structure to that of the first embodiment, but the phosphor layer in the stripe portion for emitting green light to the outside of the first embodiment emits red light and green light.
g and a phosphor layer 4b that emits blue-green light are laminated. Since it overlaps with Example 1, only the order of forming the phosphor layer will be described. The SrS: Ce film formed on the first insulating layer 31 was patterned into a phosphor layer 4b for stripes that emit blue light and green light. Next, the ZnS: Mn film formed thereon was patterned into a phosphor layer 4rg for stripes that emit red light and green light. In this way, the portions emitting green light are the phosphor layer 4b and the phosphor layer 4r.
It becomes a lamination of g. The order of film formation and patterning may be reversed. Each substrate was assembled into a multicolor light emitting EL device in the same manner as in Example 1.

With such a structure, the green color filter takes out a green color close to red from the phosphor layer 4rg and a green color close to blue from the phosphor layer 4b. It was possible to obtain green light emission with good purity and display a color image in which the green color was similarly improved. Example 4 FIG. 4 is a sectional view of a multicolor light emitting EL device according to another example of the present invention.

This embodiment differs from the third embodiment only in that a blue filter is added to the blue element portion of the second substrate. With this configuration, the blue-green light emitted from the phosphor layer 4b was removed from the green color by the blue filter, and the color purity was improved.

[0031]

According to the present invention, the overlapping portion of the element portion and the color filter in which the first electrode, the first insulating layer, the phosphor layer, the second insulating layer and the second electrode are laminated. In the multicolor light emitting EL device, which has at least the above, and which emits the light transmitted through the color filter to the outside, one of the overlapping sections is an element section having a phosphor layer made of ZnS: Mn and a red filter. And the other one of the superposed parts
One is a combination of an element part having a phosphor layer made of ZnS: Mn or a stack made of ZnS: Mn and SrS: Ce and a green filter, and a blue element part has a phosphor layer made of SrS: Ce. 2 with or without blue filter overlap
High-luminance light emission of three primary colors of R, G, and B can be obtained by using various kinds of phosphor materials, and a multicolor light emitting EL device suitable for multicolor image display can be obtained. In addition, by using two phosphor layers in the green light emitting portion or by overlapping a blue filter in the blue light emitting portion, the color purity can be improved and a multicolor light emitting EL device suitable for a full color image can be obtained. .

Further, since the phosphor layer has two layers, film formation,
Since the patterning process is performed twice in total, the number of steps is shortened and the yield is improved as compared with the conventional three times process. As a result, costs are reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multicolor light emitting EL device according to an embodiment of the invention.

FIG. 2 is a sectional view of a multicolor light emitting EL device according to another embodiment of the present invention.

FIG. 3 is a sectional view of a multicolor light emitting EL device according to another embodiment of the present invention.

FIG. 4 is a sectional view of a multicolor light emitting EL device according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional RGB independent light emitting color thin film EL device.

FIG. 6 is another color thin film E of the conventional RGB independent light emission system.
Sectional view of L display

FIG. 7 is a sectional view of a conventional color filter type color thin film EL display.

[Explanation of symbols]

 11 1st glass substrate 12 2nd glass substrate 21 1st electrode 22 2nd electrode 23 3rd electrode 24 4th electrode 31 1st insulating layer 32 2nd insulating layer 33 3rd insulating layer 34 Fourth Insulating Layer 4r Red-Emitting Phosphor Layer 4g Green-Emitting Phosphor Layer 4b Blue-Emitting Phosphor Layer 4rg Red-Green-Emitting Phosphor Layer 4gb Blue-Green-Emitting Phosphor Layer 5r Red Filter 5g Green Filter 5b Blue filter 6 Silicone oil 7 Sealing member

Claims (4)

[Claims] 1. At least an overlapping portion of a color filter and an element portion formed by laminating a first electrode, a first insulating layer, a phosphor layer, a second insulating layer and a second electrode, In a multicolor light emitting electroluminescent device that emits light that has passed through a color filter from the superimposing portion to the outside, one of the superimposing portions is a combination of an element portion having a phosphor layer made of ZnS: Mn and a red filter, Another one of the overlapping portions is a combination of an element portion having a phosphor layer made of ZnS: Mn and a green filter, and a blue element portion has a phosphor layer made of SrS: Ce. Light-emitting electroluminescent device. 2. At least an overlapping portion of a color filter and an element portion formed by laminating a first electrode, a first insulating layer, a phosphor layer, a second insulating layer and a second electrode, In a multicolor light emitting electroluminescent device that emits light that has passed through a color filter from the superimposing portion to the outside, one of the superimposing portions is a combination of an element portion having a phosphor layer made of ZnS: Mn and a red filter, The other one of the overlapping portions is a combination of an element portion having a stack of a phosphor layer made of ZnS: Mn and a phosphor layer made of SrS: Ce and a green filter, and a blue element portion made of SrS: Ce. A multicolor light emitting electroluminescent device having a phosphor layer. 3. The multicolor light emitting electroluminescent device according to claim 1, wherein a blue filter is combined with the blue element portion to form one of the overlapping portions. 4. A first substrate on which the overlapping portion is formed and a second substrate made of glass on which the color filter is formed are assembled so as to face each other. 2. The multicolor light emitting electroluminescence device according to 2 or 3.