JP2002229486A - Color display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color display element which is large in an aperture ratio and is bright and can be manufactured by a simple process. SOLUTION: At least >=2 kinds of different light emitting layers 12 are formed on respectively separate substrates 11 and sheets containing the individual substrates 11 having the respective light emitting layers 12 are laminated in a direction perpendicular to the light emitting surface, by which the color display element of the constitution capable of making color display of >=2 color is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a display device using a light-emitting device such as an organic EL, and more particularly to a color display device capable of performing color display.

[0002]

2. Description of the Related Art In a conventional color display device, white light is emitted to separate pixels into pixels corresponding to RGB and displayed through a color filter, or display is performed on the same substrate by separately applying light emitting elements that emit RGB light. . Therefore, in order to prevent the power supply line from being short-circuited or the light-emitting materials of the RBG from being mixed, the intervals between the pixels have to be always provided. In addition, if an adjacent pixel is too close, crosstalk occurs and a pixel that does not want to emit light emits light. Therefore, the ratio between the non-light-emitting portion and the light-emitting portion and the aperture ratio (the area of the light-emitting portion / the display area) are low.

In particular, in the TFT driving method, the circuit portion is large and the aperture ratio is about 50%. JP-A 1-1114
In Japanese Patent Publication No. 56, there is a report in which a light emitting portion of RGB is separated by an insulator to form a layer structure. However, in this method, since each layer is formed on the same substrate, the unevenness of the element becomes remarkable each time each layer is laminated, and as a result, the light emitting point of the RBG cannot be brought close to prevent color mixing.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color display element having a large aperture ratio, a bright display and a simple process.

[0005]

That is, the above object is achieved by the following constitution of the present invention. (1) At least two or more types of different light emitting layers are formed on separate substrates, respectively, and sheets containing the individual substrates having the respective light emitting layers are laminated in a direction perpendicular to the light emitting surface, and two or more colors are formed. Color display element capable of displaying. (2) The color display device according to (1), wherein the light emitting layer is of three types corresponding to respective colors of red, green, and blue. (3) The color display element according to (1), wherein a part of the non-light-emitting portion of at least one sheet is arranged in a portion behind the light-emitting portion of another sheet. (4) The color display element according to any one of (1) to (3), wherein a wiring electrode is formed in a part of the non-light emitting portion. (5) The color display device according to any one of the above (1) to (4), which is an organic EL device.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the color display element of the present invention, at least two or more different light-emitting layers are formed on separate substrates, respectively. Are stacked in the vertical direction, and two or more colors can be displayed.

[0007] As described above, light emitting layers of different types (emission colors) are formed on separate substrates, and sheets including the substrate on which the light emitting layers are formed are laminated to emit color light of a plurality of colors. Thereby, the pattern of the element including each light emitting layer is simplified, and the pixel formed by each light emitting layer can be enlarged. That is, since each light emitting layer is independently formed on a separate base, wiring to each light emitting layer may be formed on each base, and the wiring structure is simplified. Moreover, when laminated, the non-light emitting portion,
In particular, by arranging the wiring electrode in a portion of the other sheet behind the light emitting portion, it is possible to enlarge the size of the light emitting portion up to the non-light emitting portion.

In the present invention, the light emitting layers are formed on separate substrates. The light emitting layer in the present invention is preferably a functional film having a function of emitting electroluminescence, and has necessary constituent films, for example, an electrode, a wiring structure, an insulating layer, and the like. This functional film is capable of surface light emission,
This is preferable because uniform display quality can be obtained. Organic EL devices, inorganic EL devices, and the like are known as devices using such a functional film that emits electroluminescence. However, they can be driven at a low voltage, and can be easily formed by a thin film process and a coating process. Therefore, an organic EL element is preferable.

The substrate on which each light-emitting layer is formed is not particularly limited, as long as it can form a predetermined light-emitting layer and has transparency to light emitted from the light-emitting layer. Specifically, an amorphous substrate such as glass, quartz, etc., a crystalline substrate such as Si, GaAs, ZnS
e, ZnS, GaP, InP, and the like, and a substrate in which a crystalline, amorphous, or metal buffer layer is formed on these crystalline substrates can also be used. A resin substrate may be used to provide flexibility or reduce weight. Further, a metal substrate may be used as a substrate that is not on the light extraction side, and Mo, Al, Pt, I
r, Au, Pd or the like can be used.

The substrate is used in an emission wavelength band, usually 350 to 80.
It is preferable that the light transmittance for 0 nm, particularly for each emitted light, is 50% or more, particularly 60% or more.

Next, the color display element of the present invention will be described with reference to the drawings. FIG. 1 is a partial schematic cross-sectional view showing the basic configuration of the color display device of the present invention, and FIG. 2 is a plan view seen from the light extraction side in FIG. In this example, red (R), green (G), and blue (B) full-color display elements are shown.

In the figure, each base 11R, 11G, 11
Light emitting layers 12R, 12G, and 12B corresponding to red (R), green (G), and blue (B) are formed on B, respectively. The light-emitting layers 12R, 12G, and 12B include constituent layers having a light-emitting function and constituent layers related to the light-emitting function, such as an electrode, an insulating layer, a charge injection / transport layer, and a dielectric layer. Further, each of the light emitting layers 12R, 12G, 12
In B, wiring electrodes 13R, 13g, and 13b for supplying power (voltage and current) necessary for light emission are arranged in contact with each other. The sealing member 14 is provided on the bases 11R, 11G, and 11B on which the light emitting layers 12R, 12G, and 12B are formed.
R, 14G, and 14B are provided to protect the light emitting layer from the outside air and moisture, and also to protect against mechanical external force when the layers are stacked.

Then, the light emitting layers 12R, 12G, 12B, the wiring electrodes 13R,
Sheets on which 13g, 13b, sealing members 14R, 14G, 14B, etc. are formed are stacked in the direction perpendicular to the substrate surface, that is, the light emitting surface. In a preferred embodiment of the illustrated example, a part of the formation region of the wiring electrodes 13g and 13b, which is a non-light emitting portion, is disposed on the back surface of the light emitting layers 12R, 12G and 12B of the other sheet, that is, on the opposite side to the light extraction side. ing. For this reason, the light emission 15R, 15G, 15B from each light emitting layer 12R, 12G, 12B is transmitted to the wiring electrodes 13R, 13R.
It can be taken out without being blocked by g and 13b.

As described above, each of the light emitting layers 12R, 12G, 1
2B, that is, at least a part of the non-light-emitting portion of another sheet to be laminated is arranged on the back surface of the light-emitting region (pixel), so that the size of the light-emitting portions 12R, 12G, and 12B can be changed so far. It can be expanded to the part of the structural member that was present in the non-light emitting part. In addition, since the light emitting portions 12R, 12G, and 12B exist independently for each sheet, structural members such as wiring electrodes are also dispersed in each sheet, and the area occupied by the non-light emitting portions is small. Therefore, the light emitting portion can be enlarged accordingly.

Further, the structure of each light emitting layer is simple, driving is easy, and there is no need to worry about crosstalk, and adjustment and maintenance can be performed for each sheet.
Quality control at the time of manufacturing becomes easy, and the yield is also improved.

In the order of lamination of the sheets, a light emitting layer having a short wavelength is preferably arranged on the side near the light extraction side. By arranging a light emitting layer having a shorter wavelength on the light extraction side, the optical influence of the constituent members can be reduced. In addition, the respective sheets are preferably laminated in close contact with each other, and a member having a function of a sealing material and an adhesive and capable of protecting the EL is disposed therebetween. The stacking interval between sheets is preferably made as small as possible.

It is preferable that a part of the wiring electrode is arranged behind the light emitting layer. In particular, of the projected area which can overlap with the light emitting portion, the area overlapping with the light emitting portion is 20% or more, and more preferably 30%. % Is preferable.

Non-light-emitting portions other than the wiring electrodes include TFTs
Peripheral components such as transistors and capacitors for driving, polyimide as an edge cover, a resist material portion, and the like can be given. These may be arranged behind the light emitting unit.

FIG. 3 shows the structure of an organic EL device suitably used in the present invention. The organic EL element in the illustrated example is a substrate 2
1 / hole injecting electrode 22 / hole injecting / transporting layer 23 / light emitting layer 24 / electron injecting / transporting layer 25 / electron injecting electrode 26 are sequentially laminated, and light emission of each color is achieved by selecting a material of the light emitting layer. It is possible. Usually, the wiring electrode is
The hole injection electrode 22, the electron injection electrode 26, and a power supply (drive circuit) are connected.

As the electron injection electrode, a substance having a low work function is preferable. For example, K, Li, Na, Mg, La, C
e, Ca, Sr, Ba, Al, Ag, In, Sn, Z
It is preferable to use a single metal element such as n or Zr, or a two-component or three-component alloy system containing them for improving the stability. The electron injection electrode can be formed by an evaporation method or a sputtering method.

The thickness of the thin film of the electron injection electrode may be a certain thickness or more capable of sufficiently injecting electrons.
Preferably, the thickness may be 1 nm or more. The upper limit is not particularly limited, but the thickness may be generally about 1 to 500 nm.

The hole injection electrode usually emits light from the substrate side.
Because it is a structure that extracts light, it is transparent or translucent.
Pole is preferred. ITO (tin-doped acid)
Indium oxide), IZO (zinc-doped indium oxide)
), ZnO, SnO_Two, In_TwoO _ThreeAnd the like,
Preferably ITO (tin-doped indium oxide), IZO
(Zinc-doped indium oxide) is preferred.

The hole injection electrode has an emission wavelength band, usually 3
50 to 800 nm, especially 50% light transmittance for each emitted light.
%, Especially 60% or more.

The thickness of the hole injecting electrode may be a certain thickness or more for sufficiently injecting holes, and is preferably 5 or more.
The range is preferably from 0 to 500 nm, more preferably from 50 to 300 nm. The upper limit is not particularly limited, but if the thickness is too large, there is a fear of peeling or the like. If the thickness is too small, there is a problem in the film strength at the time of manufacturing, the hole transport ability, and the resistance value.

This hole injection electrode layer can be formed by a vapor deposition method or the like, but is preferably formed by a sputtering method.

The organic layer of the organic EL device is as follows.

For the light emitting layer, a fluorescent substance which is a compound having a light emitting function is used. Examples of such a fluorescent substance include compounds disclosed in JP-A-63-264892, for example, at least one selected from compounds such as quinacridone, rubrene, and styryl dyes. A quinoline derivative such as a metal complex dye having 8-quinolinol or a derivative thereof as a ligand, such as tris (8-quinolinolato) aluminum;
Tetraphenylbutadiene, anthracene, perylene,
Coronene, 12-phthaloperinone derivatives, and the like. Further, a phenylanthracene derivative described in JP-A-8-12600, a tetraarylethene derivative described in JP-A-8-12969, and the like can be used.

Such a fluorescent substance can be used as a dopant in combination with a host substance capable of emitting light by itself. In that case, the content of the fluorescent substance in the light emitting layer is 0.01 to 10% by mass, and further 0.1 to 5% by mass.
% By mass. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

As the host substance, a quinolinolato complex is preferable, and an aluminum complex having 8-quinolinol or a derivative thereof as a ligand is preferable. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7707
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Other host materials include those disclosed in
Also preferred are phenylanthracene derivatives described in JP-A-12600 and tetraarylethene derivatives described in JP-A-8-12969.

The light emitting layer may also serve as an electron injection / transport layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like.

As the compound capable of injecting and transporting electrons, it is preferable to use a quinoline derivative, furthermore a metal complex having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato) aluminum (Alq3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound for the hole injecting / transporting layer, it is preferable to use an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

In the present invention, the organic layer including the light emitting layer is preferably formed by a coating method. Since each light emitting layer is independently formed on a separate substrate, it is easy to form by a coating method, and there is no mixing of the light emitting layers at the time of separate coating.

In the case of forming by a coating method, for example, a light emitting layer using a polymer phosphor having high solubility, a mixed light emitting layer of a polymer phosphor and a charge transport material, or such a light emitting layer and an electron injection It has an electron injection / transport layer containing an electron injection / transport material between the electrode (negative electrode) and a hole injection / transport layer containing the hole injection / transport material between the light emitting layer and the hole injection electrode. It may be.

As such a polymeric fluorescent substance, polyethylene dioxythiophene polystyrene sulphonate (Polyethlene dioxytiophene polystyrene sulphonate) is used.
: PEDOT / PSS), polyvinyl carbazole (PVK),
Any of a metal phthalocyanine compound, polyaniline / polystyrene sulfonate (Pani / PSS), a polyparaphenylenevinylene derivative (PPV derivative), a polyallylfluorene derivative, or a mixture thereof can be given.

The metal phthalocyanine compound is not particularly limited, and may be any known one. As the central metal, Cu, Fe, Zn, Co, Pt, Cr, Ni, Pd
And the like, and Cu and Zn are preferable, and Cu is particularly preferable.

The solvent that can be used in the coating method is not particularly limited as long as the organic material dissolves and does not cause any trouble during coating. In particular,
Alcohols, hydrocarbons, ketones, ethers and the like generally used can be used. Among them, chloroform, methylene chloride, dichloroethane,
Tetrahydrofuran, toluene, xylene and the like are preferred. Although it depends on the structure and molecular weight of the phosphor, it can be usually dissolved in these solvents in an amount of 0.1% by mass or more.

The light emitting layer may be a single layer or two or more layers, and a plurality of light emitting layers and a charge transport layer may be formed. Further, the light emitting layer may contain other fluorescent materials and charge transporting materials in addition to the polymeric fluorescent material. Further, the polymeric fluorescent substance and / or the charge transport material may be dispersed in a polymeric compound.

The electron injection / transport layer and the hole injection / transport layer can be formed using an inorganic substance (eg, an oxide such as silicon, germanium, strontium, and rubidium).

After forming each layer of the organic EL element, the SiO 2
A protective film using an inorganic material such as _X, an organic material such as Teflon (registered trademark), a fluorocarbon polymer containing chlorine, or the like may be formed. The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film is
In addition to the reactive sputtering method, a general sputtering method,
It may be formed by an evaporation method, a PECVD method, or the like.

As a method of manufacturing the organic EL element, a commonly used vapor deposition method can be used, but it is preferable to manufacture the organic EL element by dissolving it in a solvent and then applying the coating method. When performing the coating method, selection may be made according to the characteristics of the solvent such as a screen printing method, a dipping method, and a spray coating method, but the spray coating method is most preferable. Further, a vapor deposition method and a coating method can be used in combination.

Further, in order to prevent deterioration of the organic layer and the electrodes of the device, it is preferable to seal the uppermost portion of the device with a sealing plate or the like. The sealing plate adheres and seals the sealing plate using an adhesive resin layer in order to prevent moisture from entering.

The material of the sealing plate is preferably a flat plate, and may be a transparent or translucent material such as glass, quartz, and resin. Glass is particularly preferred. As such a glass material, an alkali glass is preferable from the viewpoint of cost, and in addition, a glass composition such as soda lime glass, lead alkali glass, borosilicate glass, aluminosilicate glass, and silica glass is also preferable. In particular, soda glass, a glass material without surface treatment can be used at low cost,
preferable. As the sealing plate, other than a glass plate, a metal plate, a plastic plate, or the like can be used.

The height of the sealing plate may be adjusted by using a spacer, and may be maintained at a desired height. Examples of the material of the spacer include resin beads, silica beads, glass beads, and glass fibers, and glass beads are particularly preferable.

As a sealing member for protecting each light emitting layer (EL structure), an adhesive having a function of an adhesive layer with a substrate to be laminated is preferable. The adhesive is not particularly limited as long as it can maintain stable adhesive strength and has good airtightness. However, it is preferable to use a cationic curing type ultraviolet curing epoxy resin adhesive. Specifically, 3Bond released by ThreeBond
0Y-332 and the like.

[0047]

EXAMPLE A glass substrate manufactured by Corning Co., Ltd. with a trade name of 70
This was scrub-cleaned with a neutral detergent using 59 substrates.

A substrate temperature of 2 was formed on the substrate by RF magnetron sputtering using an ITO oxide target.
At 50 ° C., a 200 nm-thick ITO hole injection electrode layer was formed in a predetermined pattern. Three types of such substrates with an ITO pattern were prepared, each corresponding to RGB.

After the surface of each substrate on which the ITO electrode layer and the like were formed was washed with UV / O ₃ , a 100-nm thick film of polyethylene dioxythiophene (PEDOT, manufactured by Bayer) was formed as a hole injection layer.

Next, a distyl compound (IDE102 manufactured by Idemitsu) is used as a blue light emitter, coumarin 6 is used as a green light, and 4-dicyanomethylene-2-methyl-6- (4-dimethylaminosurityl) 4H is used as a red light. -Pyran (DCM1) was used as a dopant, and a polyvinyl carbazole (PVK) polymer was used as a host material and dissolved in a toluene solvent. Each of the solutions was applied on the substrate by a spin coating method.

Next, each substrate was vacuum-dried at 80 ° C. for 1 hour, and then LiF was deposited to a thickness of 3 nm and an Al electrode was deposited to a thickness of 80 nm.
Next, a UV-curable adhesive (30Y-3 manufactured by Three Bond Co., Ltd.)
32) using blue, green, and red panels. A sealing glass was similarly adhered thereon using a UV-curable adhesive to obtain a color light emitting device. The aperture ratio at this time was 81%.

Each panel of the obtained device was turned on and adjusted to be white. At this time, the entire light emission luminance was 300 cd / m ² . The respective light emission ratios were 28% for blue, 52% for green, and 20% for red. At this time, the driving voltages were 8 V for blue, 7 V for green, and 10 V for red. When driving this panel by time division drive,
A gradation depending on the light emission time was obtained.

[0053]

As described above, according to the present invention, it is possible to provide a color display element which has a large aperture ratio, is bright, and can be manufactured by a simple process.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a schematic configuration of a color display element of the present invention.

FIG. 2 is a plan view seen from a light extraction side in FIG. 1;

FIG. 3 is a cross-sectional view showing a basic structure of an organic EL element that can be suitably used for the color display element of the present invention.

[Explanation of symbols]

 11R, G, B Base 12R, G, B Light emitting layer 13R, G, B Wiring electrode 14R, G, B Sealing member 15R, G, B Light emission

Claims (5)

[Claims] At least two or more different light-emitting layers comprise
A color display element capable of displaying two or more colors by forming sheets containing individual substrates each having a light-emitting layer formed on a separate substrate and stacked in a direction perpendicular to the light-emitting surface. 2. The color display device according to claim 1, wherein said light emitting layers are of three types corresponding to respective colors of red, green and blue. 3. The color display element according to claim 1, wherein a part of the non-light-emitting portion of at least one sheet is arranged in a portion behind the light-emitting portion of another sheet. 4. The color display element according to claim 1, wherein a wiring electrode is formed on a part of said non-light emitting portion. 5. The color display device according to claim 1, which is an organic EL device.