JP5077007B2 - Dispersed inorganic electroluminescence panel - Google Patents

Description

  The present invention relates to a dispersed inorganic electroluminescence panel.

  Inorganic electroluminescence (inorganic EL) panels can be classified into four types according to differences in structure and operation method. There are two types of structures, a thin film type and an organic dispersion type, which are classified into a direct current operation and an alternating current operation according to the difference in operation mode when light is emitted. Among them, stable operation has been confirmed in two types of thin film type EL and dispersion type EL, both of which operate with alternating current. The former has a simple structure in which thin films are laminated by a vacuum process, has realized stable light emission, and has been studied as a display application so far. The latter can be produced by a simple process using a printing technique and has been developed as a back panel application, but its performance is not sufficient in practice, and it is considered that there are still problems to be improved. Both are common in that inorganic EL is essentially intrinsic EL, and the mechanism of light emission is electroluminescence by electrons accelerated by a high electric field. In contrast, LEDs and organic ELs are current injection types and are distinguished from inorganic ELs. Inorganic EL has a feature not available in conventional displays that a flexible light-emitting surface can be produced, and is expected as one of the next generation displays.

An AC operation type dispersion type EL (AC-EL) can be manufactured by a simple printing method and is considered to be used as a back panel. However, at present, these capabilities are limited to fields with relatively low light intensity, such as mobile phone keys and POP advertisements. In order to realize a full-color EL device, it is necessary to obtain red, blue, and green light emission with high purity.
However, there is no dispersive inorganic EL panel that can emit red light without using a color filter. For this reason, it was considered difficult to emit red light with the dispersion-type inorganic EL panel.
Patent Document 1 describes that a color conversion material is used for the purpose of a dispersion-type inorganic EL panel that gives white with high color rendering properties.
JP 2005-190732 A

The present invention has been made in view of the above circumstances, and the inorganic fluorescent material contains an inorganic fluorescent material alone, or a phosphor layer to which one or more selected from two kinds of organic dyes are added. It is an object of the present invention to provide a dispersion-type inorganic EL panel that emits light at an arbitrary point in a specific color gamut depending on the content of the body and the organic dye.
Furthermore, as a useful example of the present invention, it is an object to provide a dispersion-type inorganic EL panel that emits red light without using a color filter and a dispersion-type inorganic EL panel that emits white light.

In order to solve the above problems, the present invention provides:
A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes,
The phosphor layer contains an inorganic phosphor and two kinds of organic dyes as essential components, the inorganic phosphor is ZnS, and the organic dye is coumarin 6 and DCJTB,
By producing a panel in which the blending ratio of ZnS, Coumarin 6 and DCJTB was changed,
According to each compounding ratio,
In the CIE chromaticity coordinates, a point B whose chromaticity coordinate value is (0.16, 0.18);
A point G that is (0.26, 0.60);
Provided is a dispersion-type inorganic electroluminescent panel that emits light of one color within a range surrounded by a triangle having three vertices of three points R (0.62, 0.29) . However, point B, point G, and side BG are excluded from the triangular region.
The outline of the blending of the inorganic phosphor and the organic dye for emitting the three points R, G, and B is as follows.
Regarding the point R, the ZnS content in the phosphor paste forming the phosphor layer is 60 mass%, the coumarin 6 content is 0.05 mass%, and the DCJTB content is 0.05 mass%.
Regarding point G, the ZnS content in the phosphor paste is 60% by mass, and the content of coumarin 6 is 0.1% by mass.
About the point B, only 60 mass% of ZnS is contained in the phosphor paste.

Furthermore, the present invention is a dispersion-type inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes,
The phosphor paste forming the phosphor layer contains an inorganic phosphor and two kinds of organic dyes as essential components, the inorganic phosphor is ZnS, and the organic dye is coumarin 6 and DCJTB,
By changing the compounding ratio of ZnS, Coumarin 6 and DCJTB,
In CIE chromaticity coordinates,
CIE chromaticity coordinates of emission color from an inorganic electroluminescence panel in which the ZnS content in the phosphor paste is 60% by mass, the content of coumarin 6 is 0.05% by mass, and the content of DCJTB is 0.05% by mass Values (X1, Y1),
CIE chromaticity coordinate values (X2, Y2) of the emission color from the inorganic electroluminescence panel in which the ZnS content in the phosphor paste is 60% by mass and the content of coumarin 6 is 0.1% by mass;
CIE chromaticity coordinate values (X3, Y3) of the emission color from an inorganic electroluminescence panel containing only 60 wt% ZnS in the phosphor paste,
Provided is a dispersion-type inorganic electroluminescence panel that emits light at one point within a range surrounded by a triangle having the above three coordinate value points as vertices. However, of the range surrounded by the triangle, the panel that emits the point B, the panel that emits the point G, and the panel that emits the point on the side BG are excluded.
A method for measuring the emission color of the inorganic electroluminescence panel and determining the CIE chromaticity coordinate value will be described later.

The present invention is a dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes, wherein the phosphor layer contains an inorganic phosphor and an organic dye, and the inorganic phosphor is ZnS. The dispersion-type inorganic electroluminescence panel is characterized by containing coumarin 6 and DCJTB as the organic dye substantially in a weight ratio of 1: 1 and emitting red light.
Further, the present invention is a dispersion-type inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes, wherein the phosphor layer contains an inorganic phosphor and an organic dye, and the inorganic phosphor is ZnS. In addition, there is provided a dispersed inorganic electroluminescence panel characterized in that it contains coumarin 6 and DCJTB as the organic dye in a weight ratio of 3: 1 and emits white light.

According to the present invention, in a dispersion-type inorganic electroluminescence panel, a phosphor layer obtained by adding an inorganic phosphor and two kinds of organic dyes to the phosphor layer is used according to the contents of the inorganic phosphor and the organic dye. Thus, a dispersion-type inorganic EL panel that emits light at an arbitrary point within a specific color gamut is obtained.
Further, as a useful example of the present invention, a dispersion-type inorganic EL panel that emits red light without using a color filter and a dispersion-type inorganic EL panel that emits white light can be obtained.

The present invention will be described below based on the best mode. Unless otherwise specified, the mixing ratio and ratio are based on mass.
FIG. 1 is a cross-sectional view showing an example of a dispersion-type inorganic EL panel according to this embodiment. This inorganic EL panel has a structure in which a transparent electrode 2 is provided on one side of a transparent substrate 1, and a light emitting layer 3, a dielectric layer 4, and a back electrode 5 are laminated on the transparent electrode 2 in this order. An AC power source 6 is connected between the back electrodes 5 and light is emitted by applying an AC voltage. That is, this dispersion-type inorganic EL panel is a dispersion-type inorganic electroluminescence panel having the luminescent layer 3 and the dielectric layer 4 between the electrodes 2 and 5.

The phosphor layer 3 is a layer containing an inorganic phosphor and two kinds of organic dyes. Specifically, the inorganic phosphor is ZnS (zinc sulfide) and contains two kinds of coumarin 6 and DCJTB as organic dyes.
In the present invention, coumarin 6 is 3- (2'-benzothiazolyl) -7-diethylaminocoumarin, and DCJTB is 4- (dicyanomethylene) -2-t-butyl-6- (1,1,7 , 7-Tetramethyljulolidyl-9-enyl) -4H-pyran (in English, 4- (dicyanomethylene) -2-t-butyl-6- (1,1,7,7-tetramethylethylidyl-9-enyl)- 4H-pyran).

By changing the blending ratio of coumarin 6 and DCJTB, a wide range of white reproduction including white is possible. That is, the phosphor layer contains an inorganic phosphor and an organic dye, the inorganic phosphor is ZnS, the organic dye is coumarin 6 and DCJTB, and a wide range is obtained by changing the blending ratio of ZnS, coumarin 6 and DCJTB. Panels that emit light in a range of colors can be made.
In addition, the luminescent color from the inorganic electroluminescent panel produced by determining the blending ratio is one point. The above-mentioned wide range of colors means that the emission colors of the panels with different blending ratios cover a wide range as a whole.

By changing the compounding ratio of ZnS, coumarin 6 and DCJTB, the panels produced at the respective compounding ratios have chromaticity coordinate values (0.16, 0.18) in CIE chromaticity coordinates. B, a point G in the range surrounded by a triangle having three points, the point G being (0.26 , 0.60) and the point R being (0.62 , 0.29) , are emitted. To do.
However, the panel that emits the color of the point B, the point G, and the point on the side BG is excluded from the range surrounded by the triangle. The reason is that these points are essential requirements of the present invention and do not satisfy the condition that the phosphor layer contains ZnS, coumarin 6 and DCJTB.
In other words, in the panel surrounded by the triangle, the panel that emits the color of the area excluding the points on points B, G, and side BG has a phosphor layer of ZnS, coumarin 6 and DCJTB. Containing.

The light emitting layer is prepared by first preparing a polymer paste by mixing a high dielectric polymer and a solvent in a ratio of 7: 3. Next, an inorganic phosphor paste is prepared at a ratio of inorganic phosphor: polymer paste = 6: 4. That is, the content of the inorganic phosphor in the inorganic phosphor paste is 60%. Next, a phosphor paste having a predetermined ratio of the inorganic phosphor paste: coumarin 6: DCJTB is prepared. Then, the phosphor paste is applied to a substrate by a screen printing method as described later, and dried to form a phosphor layer.
The phosphor layer of the inorganic EL panel having the light emission color of the point R contains phosphor and organic dye in a ratio of inorganic phosphor paste: coumarin 6: DCJTB = 10: 0.005: 0.005.
The phosphor layer of the inorganic EL panel having the emission color of point G contains phosphor and organic dye in a ratio of inorganic phosphor paste: coumarin 6: DCJTB = 10: 0.01: 0. That is, it does not contain DCJTB.
The phosphor layer of the inorganic EL panel having the emission color at point B contains only an inorganic phosphor and no organic dye.

(Measurement of emission color of inorganic electroluminescence panel)
The dispersion-type inorganic EL panel of the present invention, that is, the phosphor layer contains an inorganic phosphor and an organic dye, the inorganic phosphor is ZnS, the organic dye is coumarin 6 and DCJTB, and ZnS, coumarin 6, DCJTB. By changing the blending ratio, the measurement of the spectral spectrum of light emission of the panel emitting light in a wide range and the measurement of chromaticity and luminance are performed using the following equipment. The CIE chromaticity coordinate value is a value obtained using the following equipment.

Equipment used for spectroscopic spectrum measurement:
Spectrometer: Ocean Optics USB-2000
Measuring method: Linear silicon CCD array Spectral wavelength range: 350-850 nm
Wavelength resolution: 1 nm

Equipment used for chromaticity and luminance measurement:
Color luminance meter: Konica Minolta color luminance meter CS-200
Measurement method: spectroscopy, linear sensor array Measurement range: 0.01 to 2 × 10 ⁷ cd / m ²
Chromaticity display: x, y

(Example of white light emitting panel)
When the mixing ratio of coumarin 6 and DCJTB is substantially 3: 1 by weight, white light can be emitted from the panel.
In such an inorganic EL of the present invention, the inorganic phosphor is ZnS, the first organic dye is coumarin 6, the second organic dye is DCJTB, and a part of the emission energy of the inorganic phosphor. Is converted into the emission energy of the first organic dye, and a part of the emission energy of the first organic dye obtained by the conversion is converted into the emission energy of the second organic dye. It is obtained by combining light emission of the first organic dye and light emission of the second organic dye.

(Example of red light emitting panel)
In the inorganic EL of the present invention, coumarin 6 is blended as a green fluorescent dye capable of transferring energy from the blue-emitting inorganic phosphor ZnS, and DCJTB is used as a red fluorescent dye capable of transferring energy from coumarin 6. And the mixing ratio of coumarin 6 and DCJTB is substantially 1: 1 by weight.
Thereby, a dispersion-type inorganic EL panel capable of emitting red with high color rendering properties without a color filter can be manufactured.
In such an inorganic EL of the present invention, the inorganic phosphor is ZnS, the first organic dye is coumarin 6, the second organic dye is DCJTB, and the emission energy of the inorganic phosphor is changed to the first. Substantially all of the light emission energy of the organic dye of the second organic dye is converted into the light emission energy of the first organic dye obtained by the conversion to the light emission energy of the second organic dye. Luminescence of the dye is obtained.
That is, red light emission with high color purity can be obtained using a dispersion-type inorganic electroluminescence panel containing an inorganic light-emitting body made of ZnS and an organic dye made of coumarin 6 and DCJTB.

The transparent electrode 2 is a transparent conductive film made of, for example, a transparent oxide semiconductor, and can be formed by a thin film forming method such as a sputtering method, a CVD method, or a spray pyrolysis deposition method (SPD method). Specific examples of transparent oxide semiconductors include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), tin oxide (TO), fluorine-doped zinc oxide (FZO), and aluminum dope Examples thereof include zinc oxide (AZO), gallium-doped zinc oxide (GZO), boron-doped zinc oxide (BZO), and zinc oxide (ZO). Although the thickness of a transparent conductive film is not specifically limited, For example, it is 5-500 nm in thickness.
As a material for forming the transparent electrode, a conductive polymer can be used in addition to the oxide semiconductor. Specific examples thereof include polyaniline and polyethylenedioxythiophene (PEDOT).

  The transparent electrode 2 may be formed by disposing a metal wire and / or alloy thin wire such as a comb shape or a grid shape on the transparent substrate 1 and forming a transparent conductive film thereon. Can improve the conductivity. Copper, silver, aluminum, nickel, etc. are preferably used as the fine wires of metal or alloy. If a thin line of metal and / or alloy is disposed, the light transmittance is reduced. Therefore, the transmittance of 90% or more can be achieved without excessively narrowing the distance between the thin lines or taking the width and height of the thin lines too large. It is desirable to ensure.

  The transparent substrate 1 on which the transparent electrode 2 is formed includes polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polystyrene (PS), polyethylene (PE), polyarylate (PAR). And flexible polymers such as polyetheretherketone (PEEK), polycarbonate (PC), polypropylene (PP), polyimide (PI), and triacetylcellulose (TAC). The thickness of the transparent substrate 1 is preferably 10 to 250 μm, particularly preferably 50 to 200 μm.

Examples of the dispersant used to disperse the inorganic phosphor particles in the phosphor layer 3 include a polymer having a relatively high dielectric constant such as a cyanoethyl cellulose resin, polyethylene, polypropylene, polystyrene resin, silicone resin, Resins such as epoxy resin, polymethacrylic acid resin, and vinylidene fluoride can be used. The dielectric constant can also be adjusted by appropriately mixing inorganic dielectric particles having a high dielectric constant such as BaTiO ₃ and SrTiO ₃ with these resins.

The dielectric layer 4 is a layer containing an inorganic dielectric. As the inorganic dielectric, any material can be used as long as it has a high dielectric constant and insulation and has a high dielectric breakdown voltage. As the inorganic dielectric, various metal oxides and nitrides can be used. For example, SiO ₂ , TiO ₂ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , KNbO ₃ , PbNbO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ LiTaO ₃ , Y ₂ O ₃ , Al ₂ O ₃ , ZrO ₂ , AlON, or the like can be used. These can be used alone or in combination of two or more.

  The dielectric layer 4 is preferably a layer formed by dispersing and containing inorganic dielectric particles. Examples of the dispersant used for dispersing the inorganic dielectric particles in the dielectric layer 4 include a polymer having a relatively high dielectric constant such as a cyanoethyl cellulose resin, polyethylene, polypropylene, polystyrene resin, silicone resin, Resins such as epoxy resin, polymethacrylic acid resin, and vinylidene fluoride can be used.

  The light emitting layer 3 and the dielectric layer 4 are preferably formed by applying a screen printing method, a slide coating method, a spin coating method, a dip coating method, a bar coating method, a spray coating method, or the like. For example, in the screen printing method, a layer is formed by applying a dispersion liquid in which fine particles of a light emitter or a dielectric are dispersed in a polymer solution having a high dielectric constant through a screen mesh. The film thickness can be controlled by appropriately selecting the thickness of the screen mesh, the aperture ratio, and the number of coatings, and the area can be easily increased by changing the size of the screen mesh. In particular, when the transparent substrate 1 on which the transparent electrode 2 is formed is a flexible film substrate, application of a continuous process by Roll-to-Roll can be easily realized.

  The back electrode 5 may be opaque and can be manufactured using any material having conductivity. For example, gold, silver, copper, aluminum, beryllium, cobalt, chromium, iron, germanium, iridium, potassium, lithium, magnesium, molybdenum, sodium, nickel, platinum, silicon, tin, tantalum, tungsten, zinc, and other metals, and It can be appropriately selected from conductive carbon materials such as graphite. Of these, gold, silver, copper, aluminum, beryllium, graphite and the like are preferable. The back electrode 5 can be formed by attaching a sheet or printing / coating a conductive paste. In particular, when a conductive paste is used, application of a continuous process by Roll-to-Roll can be easily realized, which is preferable.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Examples 1 and 2]
<Preparation of panel>
The structure of the produced single-sided light emitting dispersion type inorganic EL panel is shown in FIG. This dispersion-type inorganic EL panel comprises 3- (2′-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6) and 4- (dicyanomethylene) -2-t-butyl-6- (1,1, 7,7-tetramethyljulolidyl-9-ethenyl) -4H-pyran (DCJTB) added at a weight ratio of 1: 1, the dielectric layer 4, and the back electrode 5, It is the structure laminated | stacked on the transparent conductive substrate (what provided the transparent conductive layer 2 on the transparent substrate 1) in order, AC power supply 6 is connected between the transparent conductive layer 2 and the back electrode 5, Light is emitted by applying an alternating voltage.

  This dispersion-type inorganic electroluminescence panel was produced using a semi-automatic screen printer to ensure reproducibility. This panel structure is extremely simple, and the basic structure is the same as that of a conventional dispersion-type inorganic EL panel.

  As the phosphor used for the phosphor layer, granular ZnS inorganic phosphor (GG65: manufactured by OSRAM SYLVANIA) was used. This phosphor has an emission spectrum peak at 450 nm.

  The light emitting layer and the dielectric layer were prepared based on a paste prepared by preparing a high dielectric polymer (cyanoresin CR-V: manufactured by Shin-Etsu Chemical Co., Ltd.) and cyclohexanone in a weight ratio of 7: 3, respectively. This polymer CR-V has a relatively high dielectric constant, and has a high dipole moment and dielectric constant by reacting its hydroxyl group with acrylonitrile.

The phosphor layer was prepared by mixing the inorganic phosphor and the paste at a weight ratio of 6: 4 to prepare an inorganic phosphor paste, and then coumarin 6 (hereinafter referred to as “coumarin 6”) with respect to 10 parts by weight of the inorganic phosphor paste. In some cases, the phosphor paste was prepared by adding 0.005 parts by weight of DCJTB and 0.005 parts by weight of DCJTB.

Further, the dielectric layer was formed using a dielectric paste prepared by blending the paste with a barium titanate (BaTiO ₃ ) powder.
The back electrode was formed using a silver paste (FEA-685: manufactured by Fujikura Kasei Co., Ltd.) containing silver (Ag) as a main component.
As the transparent conductive substrate, an indium tin oxide (ITO) glass substrate having a surface resistance value of 130Ω / □ was used.

  The inorganic EL panel according to the example was manufactured by sequentially applying a phosphor paste, a dielectric paste, and a silver paste on the above-described transparent conductive substrate by a screen printing method.

  For the evaluation of the produced EL panel, an EL characteristic measurement system SX-1111 (manufactured by Iwatori Measurement Co., Ltd.) was used. The film thickness of each layer (specifically, as will be described later) is determined by observing the cut surface of the EL panel using a scanning electron microscope (S-2700: manufactured by Hitachi). It was measured.

<Results and discussion>
The luminance of the dispersion-type inorganic EL panel varies depending on different operating conditions because the thickness of the panel depends on the applied electromotive force and frequency. The operating conditions of the inorganic EL panel in which the organic dye is dispersed are considered to be the same as the operating conditions of a normal dispersion type inorganic EL panel. In this example, the measurement was performed by inputting an alternating current having a sine waveform within a frequency range of 1 to 20 kHz.

  The film thicknesses of the light emitting layer and the dielectric layer were measured by observation using the above scanning electron microscope (SEM), and as a result, were about 30 μm.

FIG. 2 shows the dependence of the emission spectrum on the AC frequency in the dispersion-type inorganic EL panel according to this example.
FIG. 2A shows an emission spectrum of the inorganic EL panel according to Example 1, which is added to the phosphor layer at a ratio of coumarin 6 (C6): DCJTB = 1: 10. FIG. 2B shows an emission spectrum of the inorganic EL panel according to Example 2, which is added to the phosphor layer at a ratio of coumarin 6 (C6): DCJTB = 1: 1.
For each of the inorganic EL panels (a) and (b), the AC frequency is 1 kHz (white circle), 5 kHz (black triangle), 10 kHz (white triangle), 15 kHz (black square), and 20 kHz (white). The EL emission spectrum was measured under the conditions of the squares of (2), and the EL emission spectra at each frequency were superimposed and displayed on a graph.

  In Example 1 (C6: DCJTB = 1: 10) shown in FIG. 2A, the peak of the EL emission wavelength appeared at about 450 nm and about 650 nm. These peaks are derived from ZnS and DCJTB, respectively. Under this condition, a peak at about 520 nm derived from coumarin 6 was not observed.

  In Example 2 (C6: DCJTB = 1: 1) shown in FIG. 2B, the peak at about 450 nm derived from ZnS decreased and the peak at about 650 nm derived from DCJTB mainly appeared. Also at this time, a peak at about 520 nm derived from coumarin 6 was not observed.

  The result of Example 1 can be considered as follows. In the first stage, by adding coumarin 6 to the phosphor, the EL spectrum shifts significantly to the high wavelength side, and the peak shifts from 450 nm to 520 nm. In the next step, the peak shifts from 520 nm to 650 nm by adding DCJTB to the phosphor. Such a decrease is considered due to the transfer of excitation energy from the inorganic phosphor to the organic fluorescent dye. Since no peak derived from coumarin 6 was observed in the example shown in FIG. 2 (a), coumarin 6 does not emit light itself, but an additive (dopant) that assists (assists) the emission of DCJTB. It is thought that it functions as.

When the compounding ratio of C6: DCJTB was changed, the emission wavelength could be controlled as can be seen from the spectra of FIGS. 2 (a) and 2 (b). Here, red light emission could be realized at a blending ratio of C6: DCJTB = 1: 1. Further, when the mixing ratio was C6: DCJTB = 1: 1, the same emission spectrum was shown in the range of AC frequency of 1 to 0 kHz, and all emitted red light.
According to the present invention, by co-addition of the green dye coumarin 6 and the red dye DCJTB, the blue energy of the ZnS illuminant transitioned to almost 100% DCJTB, giving red light emission with high color rendering properties.
Accordingly, the present invention solves the problem of low red purity in the dispersion-type inorganic EL.

FIG. 3 shows the luminance-voltage (LV) characteristics of the inorganic EL panel in Example 2 described above. The EL emission spectrum was measured under the condition that the AC frequency was 1 kHz and 20 kHz, and the EL emission spectrum at each frequency was superimposed and displayed on the graph. Red emission of the panel when the applied voltage is 240V is, 20 kHz in indicates the luminance of 850 cd / ^{m 2,} it exhibited a luminance of 110 cd / ^{m 2} at 1 kHz. The luminance of the dispersion-type inorganic EL panel in this embodiment is about the same as the luminance of the conventional thin-layer inorganic EL panel.

  FIG. 4 shows a graph in which the chromaticity of EL emission of the inorganic EL panel of Example 2 is plotted on chromaticity coordinates (XYZ color system) of the International Lighting Commission (Commission Internationale de l'Eclairage, abbreviated as CIE). . That is, the applied alternating current frequencies are 1 kHz, 5 kHz, 10 kHz, 15 kHz, and 20 kHz, and the EL light emission coordinate values are obtained, and the five coordinate values are respectively indicated by “◯”. The average coordinate values were x = 0.62 and y = 0.29, and it was confirmed that red light emission was obtained with the dispersion-type inorganic EL panel without using a color filter. Moreover, even if the AC frequency was changed, the coordinate value hardly changed.

[Example 3]
When preparing the phosphor paste, a mixture of 0.0075 parts by weight of coumarin 6 and 0.00125 parts by weight of DCJTB is added to 10 parts by weight of the inorganic phosphor paste, and C6: DCJTB = 3: 1 An inorganic EL panel was produced in the same manner as in Example 1 except for the ratio.

  FIG. 5 shows the dependence of the emission spectrum on the AC frequency in the dispersion-type inorganic EL panel according to Example 3. The EL emission spectrum was measured under the conditions of AC frequency of 1 kHz, 10 kHz, and 15 kHz, and the EL emission spectrum at each frequency was superimposed and displayed on a graph. In addition, color rendering properties, chromaticity coordinates, and color temperature at an applied voltage of 240 V were measured. The results are shown in Table 1.

  According to this example, by setting the mixing ratio of C6: DCJTB = 3: 1, a similar emission spectrum was shown in the range of AC frequency of 1 to 15 kHz, and all gave white light emission with a wide color reproduction range. .

[Reference example]
In the conventional color conversion technique, the color (blue green) of the ZnS light emitter is always reproduced.
In addition, as a reference example, an inorganic EL panel in which ZnS and DCJTB are added to the light emitter layer (in which the coumarin 6 is omitted from the configuration of Example 1) was prepared, and the EL spectrum was measured, which was derived from the ZnS light emitter. A peak at 450 nm appeared prominently and was observed as bluish red (purple). From this, it can be considered that if there is no coumarin 6, only a part of the blue energy of the ZnS light emitter has transitioned to DCJTB.

  INDUSTRIAL APPLICABILITY The present invention is useful for applications requiring red light emission in a dispersion-type inorganic electroluminescence panel, and can be expected to be applied to backlights for liquid crystal displays, POPs, traffic advertisements, outdoor advertisements, and the like.

It is sectional drawing which shows the structure of an inorganic EL panel typically. An example of measuring the frequency dependence of the emission spectrum in an inorganic EL panel is shown, with (a) having a blending ratio of C6: DCJTB = 1: 10 and (b) having a blending ratio of C6: DCJTB = 1: 1. It is a graph which shows the result. 6 is a graph showing luminance-voltage characteristics of an inorganic EL panel of Example 2. 6 is a graph in which the chromaticity of EL emission of the inorganic EL panel of Example 2 is plotted on CIE chromaticity coordinates. 6 is a graph showing an example of measurement of frequency dependence of an emission spectrum in an inorganic EL panel of Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent base material, 2 ... Transparent conductive layer, 3 ... Light emitter layer, 4 ... Dielectric layer, 5 ... Back electrode, 6 ... AC power supply.

Claims (5)

A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes,
The phosphor layer contains an inorganic phosphor and two kinds of organic dyes as essential components, the inorganic phosphor is ZnS, and the organic dye is coumarin 6 and DCJTB,
By changing the blending ratio of ZnS, Coumarin 6 and DCJTB,
In the CIE chromaticity coordinates, a point B whose chromaticity coordinate value is (0.16, 0.18);
A point G that is (0.26, 0.60);
Dispersion characterized by emitting one color of a region (excluding point B, point G, and side BG) surrounded by a triangle having apexes of three points R (0.62, 0.29) Type inorganic electroluminescence panel. A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer containing an inorganic phosphor and an organic dye between electrodes,
The light emission energy of the inorganic phosphor is substantially entirely converted to the light emission energy of the first organic dye, and the light emission energy of the first organic dye obtained by the conversion is substantially converted to the light emission energy of the second organic dye. By converting all, light emission of the second organic dye can be obtained,
The inorganic phosphor is ZnS;
The first organic dye is coumarin 6;
A dispersion-type inorganic electroluminescence panel in which the second organic dye is DCJTB. A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes,
The phosphor layer contains an inorganic phosphor and an organic dye, the inorganic phosphor is ZnS, and coumarin 6 and DCJTB are substantially contained at a weight ratio of 1: 1 as the organic dye to emit red light. The dispersed inorganic electroluminescence panel according to claim 2 , wherein A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer containing an inorganic phosphor and an organic dye between electrodes,
A part of the emission energy of the inorganic phosphor is converted into the emission energy of the first organic dye, and a part of the emission energy of the first organic dye obtained by the conversion is converted into the emission energy of the second organic dye. By doing so, the light emission of the inorganic luminescent material, the light emission of the first organic dye, the light emission of the second organic dye is combined,
The inorganic phosphor is ZnS;
The first organic dye is coumarin 6;
A dispersion-type inorganic electroluminescence panel in which the second organic dye is DCJTB. A dispersive inorganic electroluminescence panel having a phosphor layer and a dielectric layer between electrodes,
The phosphor layer includes an inorganic phosphor and an organic dye, the inorganic phosphor is ZnS, and coumarin 6 and DCJTB are substantially contained at a weight ratio of 3: 1 as the organic dye to emit white light. The dispersed inorganic electroluminescence panel according to claim 4 , wherein

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