TW201434533A - Method of manufacturing fluorescent substance for dispersion type EL - Google Patents

Abstract

A fluorescent substance for dispersion type EL capable of achieving high luminance and luminous efficiency is efficiently manufactured by only a simple process. A method of manufacturing a fluorescent substance for dispersion type EL includes at least a first firing step of firing a mother particle (step S2), a first impregnating step of impregnating the first-fired mother particle with a P-type activator or an N-type activator (step S4), a second impregnating step of impregnating the first-impregnated mother particle with the N-type activator or the P-type activator (step S8), a final firing step of firing the second-impregnated mother particle (step S9), and a cleaning step of cleaning the final-fired mother particle (step S10).

Description

Method for producing phosphor for dispersion type EL

The present invention relates to a method for producing a phosphor for dispersion type electroluminescent light (hereinafter referred to as "dispersion type EL").

The dispersion type EL is a device in which a powdery phosphor material is dispersed in a resin binder or the like, applied to an electrode, an electrode is formed thereon, and an electric field is applied to the phosphor material to emit light. On the other hand, a film formed by vapor deposition, sputtering, or the like of a phosphor material is referred to as "thin film EL". Since the phosphor layer of the thin film EL is as thin as 1 μm or less and a high electric field can be applied, various phosphor materials can be made to emit light.

On the other hand, since the dispersion type EL forms a layer of a phosphor by coating a powdery phosphor, the thickness of the layer is several 10 μm or more, and a high electric field cannot be applied. Therefore, the user of the dispersion type EL is a so-called "D-A pair type fluorescence", and the type is limited. At present, ZnS is added to a phosphor for dispersion type EL by adding an activator such as Cu or Ag or a co-activator such as Cl, I or Al. Such a phosphor is injected into a conductive strip of a phosphor particle or an electron or a hole in a valence band, via a donor level introduced by a co-activator, and using an activator. The formed acceptor level is recombined to obtain luminescence.

The mechanism for carrier injection is understood to be based on the mechanism of precipitating Cu ₂ S (copper sulfide) in the ZnS crystal, and releasing electrons or electricity from the conductive Cu ₂ S when an electric field is applied. The hole is supplied to the ZnS crystal (refer to Non-Patent Document 1).

It is known that in ZnS particles, electrons or holes which are precipitated from a sufficient amount of Cu ₂ S are likely to form a build-up defect (the interface between the zinc blende type crystal and the wurtzite type crystal) in the ZnS crystal, and it is necessary to pass through a complicated The thermal step causes acicular Cu ₂ S crystals to precipitate at the interface. Therefore, in the production step of the phosphor, a step of applying an impact to the ZnS crystal (refer to Patent Document 1) or applying a high pressure (see Patent Document 2) is introduced in order to impart distortion. In addition, there is a method of applying a shock wave (see Patent Document 3) and exposing it together with an explosive in a sealed container (see Patent Document 4).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 2696809

[Patent Document 2] Japanese Patent Laid-Open Publication No. 08-283711

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2007-224174

[Patent Document 4] International Publication No. 2007/043676

[Non-patent literature]

[Non-Patent Document 1] The Institute of Image Information and Television Engineers Technical Report 14 (4), pp. 31-35, 1990.

However, the steps of the methods described in Patent Documents 1 to 4 are difficult to control, and it is not always possible to manufacture according to optimum conditions, and the yield (yield) of the product is also inferior. In addition, there are potential problems in engineering that require high energy, resulting in increased costs.

The present invention has been made in view of the above-described technical problems, and an object thereof is to provide a dispersion type EL phosphor which can obtain high luminance and high luminous efficiency without requiring complicated control and special steps requiring high energy. A method that can be efficiently manufactured by simple steps.

The present invention relates to a method for producing a dispersion-type EL phosphor obtained by adding an activator and a co-activator to the matrix particles. In the present invention, after the activator or co-activator is impregnated into the precursor particles, the activator or co-activator is added to the matrix particles by calcination.

Specifically, the method for producing a phosphor for a dispersion type EL according to the present invention includes at least an initial calcination step, a first impregnation step, a second impregnation step, a final calcination step, and a washing step. The initial calcination step is to calcine the parent particles. The first impregnation step is such that the precursor particles after the initial calcination step are impregnated with an activator or a co-activator. The second impregnation step is performed by impregnating the matrix particles after the first impregnation step with a co-activator or an activator. The washing step is to wash the mother particles after the second impregnation step.

According to the phosphor for dispersion type EL obtained by the above production method, a part of the matrix particles is replaced by an activator, and the rest is replaced by a co-activator, whereby the phosphor particles have a structure in which a pn junction is formed. By this configuration, recombination of electrons and holes occurs at the pn junction portion, and light emission can be caused even under the condition that a low electric field can be applied as in the dispersion type EL structure.

Further, in the above-described manufacturing step, since it is not necessary to distort the ZnS crystal to precipitate Cu ₂ S, it is possible to reduce the cost of the high-energy, explosion, shock wave, etc., which is difficult to control, and at a low cost. A phosphor for dispersion type EL is produced with good yield.

The above-described plural steps are essential to the present invention, but various steps may be further added to improve the manufacturing efficiency. Specifically, an intermediate calcination step of calcining the precursor particles after the first impregnation step is further added. Further, a washing step of washing the mother particles after the intermediate calcination step may be added. Further, a washing step of washing the mother particles after the first calcination step may be added.

Further, in order to enable the impregnation activator and the co-activator, respectively, the impregnation step may be divided into two times as described above, but a simpler method may simultaneously impregnate both the activator and the co-activator by a single impregnation step.

Further, the method for producing a phosphor for dispersion type EL of the present invention includes at least a synthesis step, a first calcination step, an impregnation step, a final calcination step, and a washing step. The synthesis step is the synthesis of the parent particles in a liquid phase containing an activator or co-activator. The initial calcination step is to calcine the parent particles obtained by the synthesis step. The impregnation step is such that the parent particles after the initial calcination step are impregnated with a co-activator or activator. The final calcination step is to calcine the parent particles after the impregnation step. The washing step is to wash the mother particles after the impregnation step.

In the phosphor for dispersion type EL obtained by the above production method, a part of the precursor particles is replaced by an activator, and the rest is replaced by a co-activator, whereby the phosphor particles have a structure in which a pn junction is formed. By this configuration, recombination of electrons and holes occurs at the pn junction portion, and light emission can be caused even under the condition that a low electric field can be applied as in the dispersion type EL structure.

Further, in the above-described manufacturing step, the dispersion-type EL phosphor is produced at a low cost and at a good yield because the high-energy, explosion, shock wave and the like are required to be high-power and difficult to control.

The above-described plural steps are essential to the present invention, but various steps may be further added to improve the manufacturing efficiency. Specifically, a washing step of washing the mother particles after the first calcination step may be added.

According to the present invention, a phosphor for a dispersion type EL which can obtain high luminance and high luminous efficiency can be efficiently manufactured only in a simple step without requiring complicated control and a special step requiring high energy.

Fig. 1 is a flow chart showing the flow of a method for producing a phosphor for a dispersion type EL according to the first embodiment of the present invention.

Fig. 2 is a flow chart showing the flow of a method for producing a dispersion-type EL phosphor according to a second embodiment of the present invention.

Fig. 3 is a flow chart showing the flow of a method for producing a dispersion-type EL phosphor according to a third embodiment of the present invention.

A method of producing a dispersion-type EL phosphor according to the first embodiment of the present invention will be described.

As shown in FIG. 1, the method for producing a phosphor for a dispersion type EL according to the present embodiment includes a preparation step of a crystal particle of a precursor material (step S1), a first calcination step (step S2), and a washing step ( Step S3), first impregnation step (step S4), intermediate calcination step (step S5), washing step (step S6), drying step (step S7), second impregnation step (step S8), final calcination step (step S9), a washing step (step S10), and a drying step (step S11).

The preparation step (step S1) prepares the precursor particles which are the basis of the dispersion-type EL phosphor of the present invention. The precursor particles are preferably used as the most common ZnS crystal particles for the dispersion type EL phosphor. The ZnS crystal particles can be synthesized by various known methods, and one example is synthesized by a liquid phase synthesis method. The liquid phase synthesis method obtains a product in the form of fine crystals.

The initial calcination step (step S2) calcins the ZnS crystal particles belonging to the parent particles. By calcination, the parent particles are converted into a property suitable for the phosphor for dispersion type EL. Next, the calcined mother particles are subjected to water washing by a washing step (step S3). This washing step can be omitted.

The first impregnation step (step S4) is a method of impregnating an activator or a co-activator with the precursor particles subjected to the initial calcination step (strictly calcined and then washed, the parent particles).

In the present invention, the term "activator" means an electron acceptor property (a property of generating a hole carrier) in ZnS crystal particles belonging to a parent particle, and specifically, one or more elements selected from Group 11 or Group 15 elements. . For example, Cu, Ag, P, As, and the like. Cu, Ag and ZnS particles are substituted by Zn, while P and As are substituted with S of ZnS particles.

In the present invention, the term "co-activator" means an electron imparting property (a property of generating an electron carrier) in a ZnS crystal particle belonging to a parent particle, and is specifically selected from a group 13 or group 17 element. 1 or more elements. For example, Al, Ga, Cl, Br, I, and the like. Al, Ga, and ZnS particles are substituted by Zn, while Br and I are substituted with S of ZnS particles.

The first impregnation step is carried out by impregnating the parent particles with an aqueous solution of an activator or a co-activator. When such an aqueous solution, for example, an activator, Cu is used as a target, a CuCl aqueous solution can be used; when the coactivator is based on Al or Cl, an aqueous solution of AlCl ₃ can be used.

The intermediate calcination step (step S5) is to calcine the mother particles subjected to the first impregnation step. Thereby an activator or co-activator is added to the parent particles. Next, the mother particles subjected to the calcination step (step S6) are washed, and then dried by a drying step (step S7). The cleaning liquid is appropriately selected depending on the element of the impregnating activator or co-activator. For example, when an aqueous solution of CuCl is used as the impregnation liquid, ammonia water is preferably used as the washing liquid, and when the aqueous solution of AlCl ₃ is used as the impregnation liquid, hydrochloric acid is preferably used as the washing liquid.

The second impregnation step (step S8) is performed by subjecting the parent particles subjected to the first impregnation step (strictly, the calcined/washed parent particles after performing the first impregnation step), impregnating the co-activator or Activator. That is, when the activator is impregnated by the first impregnation step, it is convenient to impregnate the co-activator with the second impregnation step. On the other hand, when the first impregnation step is used to impregnate the co-activator, it is convenient to impregnate the activator with the second impregnation step. The above-mentioned one may be used as the co-activator or activator impregnated in the second impregnation step. The second impregnation step is carried out by impregnating the parent particles with an aqueous solution of a compound of a co-activator or an activator. Such an aqueous solution can be used as described above.

The final calcination step (step S9) is to calcine the mother particles subjected to the second impregnation step. Thereby, a co-activator or activator is added to the parent particles. Further, the calcination temperature is preferably from 100 ° C to 500 ° C, more preferably from 200 ° C to 400 ° C. Thereby, an illuminating center derived from segregation of an activator and a co-activator can be formed on the surface of the mother particle. Next, the calcined mother particles are washed by a washing step (step S10), and then dried by a drying step (step S11). The above can be used as the washing liquid. As a result, a phosphor for inorganic EL comprising an activator and a co-activator added to the matrix particles can be obtained.

According to the above-described phosphor for dispersion type EL, a part of the matrix particles is substituted with an activator to form a p-type, and the remaining part is replaced by a co-activator to become n. Form, while forming a pn junction in the phosphor particles. By this configuration, recombination of electrons and holes occurs at the pn junction portion, and light emission can be caused even under the condition that a low electric field can be applied as in the dispersion type EL structure.

A method of producing a dispersion-type EL phosphor according to a second embodiment of the present invention will be described. In the first embodiment, the activator and the co-activator are impregnated with the parent particles twice by the first impregnation step and the second impregnation step. However, in the present embodiment, the activator and the coactivator are used in a single impregnation step. Both sides are impregnated at the same time, and the manufacturing steps can be simplified.

As shown in FIG. 2, the method for producing a phosphor for a dispersion type EL according to the present embodiment includes a preparation step of a crystal particle of a precursor material (step S21), a first calcination step (step S22), and a washing step ( Step S23), an impregnation step (step S24), a final calcination step (step S25), a washing step (step S26), and a drying step (step S27).

The preparation step (step S21) prepares the precursor particles which are the basis of the dispersion-type EL phosphor of the present invention. The precursor particles are preferably used as the most common ZnS crystal particles for the dispersion type EL phosphor. The ZnS crystal particles can be synthesized by various known methods, and one example is synthesized by a liquid phase synthesis method. The liquid phase synthesis method obtains a product in the form of fine crystals.

The initial calcination step (step S22) calcins the ZnS crystal particles belonging to the parent particles. By calcination, the parent particles are converted into a property suitable for the phosphor for dispersion type EL. Next, the calcined mother particles are washed with water by a washing step (step S23). This washing step can be omitted.

The impregnation step (step S24) is carried out by subjecting the precursor particles subjected to the initial calcination step (strictly, the washed parent particles after calcination), the impregnation activator and the co-activator.

The term "activator" as used in the present invention means a ZnS junction belonging to a parent particle. The electron accepting property (the property of generating a hole carrier) in the crystal grain is specifically one or more elements selected from the group 11 or group 15 elements. For example, Cu, Ag, P, As, and the like. Cu, Ag and ZnS particles are substituted by Zn, while P and As are substituted with S of ZnS particles.

In the present invention, the term "co-activator" means an electron imparting property (a property of generating an electron carrier) in a ZnS crystal particle belonging to a parent particle, and is specifically selected from a group 13 or group 17 element. 1 or more elements. For example, Al, Ga, Cl, Br, I, and the like. Al, Ga, and ZnS particles are substituted by Zn, while Br and I are substituted with S of ZnS particles.

The impregnation step is carried out by impregnating the parent particles with an aqueous solution of the activator and the co-activator. In such an aqueous solution, for example, when the activator is based on Cu and the coactivator is based on Al or Cl, a mixed aqueous solution of CuCl, CuCl ₂ and AlCl ₃ can be used.

The final calcination step (step S25) is to calcine the parent particles subjected to the impregnation step. Thereby, a co-activator or activator is added to the parent particles. Next, the calcined mother particles are washed by a washing step (step S10), and then dried by a drying step (step S11). As a result, a phosphor for inorganic EL comprising an activator and a co-activator added to the matrix particles can be obtained.

According to the dispersion type EL phosphor obtained as described above, a part of the precursor particles is substituted with an activator to be p-type, and the remaining portion is substituted with a co-activator to form an n-type, and a pn junction is formed in the phosphor particles. . By this configuration, recombination of electrons and holes occurs at the pn junction portion, and light emission can be caused even under the condition that a low electric field can be applied as in the dispersion type EL structure.

Next, a specific embodiment for verifying the effects of the first and second embodiments will be described.

[Example 1]

The precursor of the ZnS phosphor was precipitated by liquid phase synthesis, and by calcination, ZnS microcrystals having a particle diameter (D50) of about 10 μm were obtained. Next, the crystal particles were washed with water, dried at 100 ° C to 300 ° C, and then introduced into a CuCl aqueous solution to impregnate Cu. It is calcined, washed with ammonia water, impregnated with Al and Cl in an aqueous solution of AlCl ₃ , calcined at 100 ° C to 500 ° C, washed with hydrochloric acid, and dried at 100 ° C to 300 ° C. A phosphor powder is obtained.

A light-emitting layer was formed on the ITO transparent electrode film side of the PET film on which the ITO (indium oxide) transparent electrode film was formed on one side. The luminescent layer is obtained by coating a phosphor paste obtained by mixing the phosphor powder with the binder resin as described above by a binder ratio of 5:1 to a transparent electrode, and calcining the film after calcination. The film formation was carried out in such a manner that the thickness became about 60 μm. The dielectric layer is a dielectric paste in which barium titanate (BaTiO ₃ ) particles and a binder resin are mixed at a weight ratio of 3:1, and is applied onto a light-emitting layer, and calcined to form a film thickness after calcination. Film formation was carried out in a 20 μm manner. Finally, an Ag paste was applied onto a dielectric material and calcined to form a back electrode, whereby the dispersion type EL device of Example 1 was obtained.

[Embodiment 2]

The precursor of the ZnS phosphor was precipitated by liquid phase synthesis, and by calcination, ZnS microcrystals having a particle diameter (D50) of about 10 μm were obtained. Next, the crystal particles are washed with water, dried at 100 ° C to 300 ° C, and then introduced into a mixed aqueous solution of CuCl or AlCl ₃ to impregnate Cu, Al, and Cl. Then, calcination is carried out at 100 ° C to 500 ° C, and ammonia washing is carried out, and the phosphor powder is obtained by drying at 100 ° C to 300 ° C.

The dispersion-type EL element of Example 2 was produced in the same manner as in Example 1 except that the light-emitting layer containing the phosphor powder obtained as described above was provided.

[Comparative Example 1]

The precursor of the ZnS phosphor was precipitated by liquid phase synthesis, and by calcination, ZnS microcrystals having a particle diameter (D50) of about 10 μm were obtained. At this time, the activator is simultaneously added with Cu and Al according to the liquid phase, and after being calcined at 800 ° C to 900 ° C, it is washed, and then dried at 100 ° C to 300 ° C to obtain a phosphor powder.

A dispersion type EL device of a comparative example was produced in the same manner as in Example 1 except that the light-emitting layer containing the phosphor powder obtained as described above was provided.

<Lighting characteristics test>

The light-emitting characteristics of the dispersion-type EL elements of Examples 1 and 2 and Comparative Example 1 produced as described above were evaluated. The dispersion type EL element is driven by an alternating current of 10 kHz and an actual value of 215V. Table 1 summarizes the brightness and luminous efficiency at this time. In the first and second embodiments, the luminance was about 2 times and the luminous efficiency was nearly 2 to 3 times as compared with the comparative example 1.

The reason why the luminescent properties of the examples and the comparative examples are significantly different can be estimated as follows. In Comparative Example 1, an activator and a co-activator were added when ZnS crystals were synthesized in a liquid phase. Therefore, the activator and the co-activator are more uniformly dispersed in the crystallization, and a clear pn junction is not formed. On the other hand, Example 1 is initially impregnated with an activator, followed by impregnation of a co-activator, whereby a two-layer structured surface layer of an activator and a co-activator is formed on the surface of the phosphor particles, and a pn junction is formed at the interface. Judging will increase brightness and luminous efficiency.

In the second embodiment, although the activator and the co-activator are simultaneously impregnated, since the adsorption rates of the ZnS crystal surface are different, and the diffusion coefficient toward the crystal is different, the activity is There is a difference in concentration between the agent and the co-activator. Therefore, a pn junction is formed between the portion having a higher concentration of the activator and the portion having a higher concentration of the co-activator, and thus it is presumed that the luminescent property when the phosphor for the dispersion type EL is used is improved. Further, in the first embodiment, the impregnation sequence may be replaced.

A method of producing a dispersion-type EL phosphor according to a third embodiment of the present invention will be described.

As shown in FIG. 3, the method for producing a phosphor for a dispersion type EL according to the present embodiment includes a step of synthesizing crystal particles of a precursor material (step S31), a first calcination step (step S32), and a washing step ( Step S33), a drying step (Step S34), an impregnation step (Step S35), a final calcination step (Step S36), a washing step (Step S37), and a drying step (Step S38).

The synthesis step (step S31) is a precursor particle which is a base of the dispersion-type EL phosphor of the present invention in a state in which an activator or a co-activator is impregnated. Therefore, the synthesis step is carried out by a liquid phase synthesis method in which a product precipitates in a liquid phase containing an activator or a co-activator. The liquid crystal synthesis method obtains a product in the form of fine crystals.

The precursor particles are preferably used as the most common ZnS crystal particles for the dispersion type EL phosphor.

In the present invention, the term "activator" means an electron acceptor property (a property of generating a hole carrier) in the ZnS crystal particles belonging to the parent particle, and specifically, one or more selected from the group 11 or group 15 element. element. For example, Cu, Ag, P, As, and the like. Cu, Ag and ZnS particles are substituted by Zn, while P and As are substituted with S of ZnS particles.

In the present invention, the term "co-activator" means an electron imparting property (a property of generating an electron carrier) in a ZnS crystal particle belonging to a parent particle, and is specifically selected from a group 13 or group 17 element. 1 or more elements. For example, Al, Ga, Cl, Br, I, and the like. Al, Ga and ZnS particles are substituted by Zn, while Br, I and ZnS particles are substituted. S is replaced.

The initial calcination step (step S32) is performed by synthesizing according to the synthesis step, and calcining the ZnS crystal particles belonging to the parent particles by adding an activator or a co-activator. By calcination, the parent particles are converted into a property suitable for the phosphor for dispersion type EL. Next, the calcined mother particles are washed by a washing step (step S33), and then dried by a drying step (step S34). The cleaning liquid is appropriately selected depending on the element of the impregnating activator or co-activator. For example, when the activator is added with Cu, the washing liquid is preferably aqueous ammonia, and when the activator is added with Al or Cl, the washing liquid is preferably hydrochloric acid. The washing step and the drying step can be omitted.

The impregnation step (step S35) is carried out by impregnating the parent particles (in strict case, after calcination, and then washing and drying the precursor particles) with the co-activator or activator. That is, when an activator is added in accordance with the synthesis step, it is convenient to impregnate the co-activator with the impregnation step. On the other hand, when a co-activator is added in accordance with the synthesis step, it is convenient to impregnate the activator with the impregnation step.

The impregnation step is carried out by impregnating the parent particles with an aqueous solution of an activator or a co-activator. Such an aqueous solution is, for example, an AlCl ₃ aqueous solution when the coactivator is based on Al or Cl; and when the activator is Cu as a target, an aqueous CuCl solution can be used.

The final calcination step (step S36) is to calcine the parent particles subjected to the impregnation step. Thereby, a co-activator or activator is added to the parent particles. Next, the calcined mother particles are washed by a washing step (step S37), and then dried by a drying step (step S38). As a result, a phosphor for inorganic EL comprising an activator and a co-activator added to the matrix particles can be obtained. The above-mentioned one can be suitably used for the washing liquid.

a dispersion type EL phosphor obtained as described above, wherein the matrix particles are A portion will be replaced by an activator to form a p-type, while the remainder will be replaced by a co-activator to form an n-type, while a pn junction is formed in the phosphor particles. By this configuration, recombination of electrons and holes occurs at the pn junction portion, and light emission can be caused even under the condition that a low electric field can be applied as in the dispersion type EL structure.

Next, a specific embodiment for verifying the effects of the third embodiment will be described.

[Example 3]

The precursor of the ZnS phosphor was precipitated by liquid phase synthesis, and by calcination, ZnS microcrystals having a particle diameter (D50) of about 10 μm were obtained. At this time, the activator is added with Cu in a liquid phase, and the p-type ZnS is first made to occupy almost all of the crystal particles. Then, the crystal particles are washed with aqueous ammonia, washed with water, and dried at 100 ° C to 300 ° C to remove Cu from the surface of the ZnS. The ZnS particles were placed in an aqueous solution of AlCl ₃ and impregnated with Al and Cl. Then, calcination is carried out at 100 ° C to 500 ° C, and washing with hydrochloric acid is again carried out, and the phosphor powder is obtained by drying.

A light-emitting layer was formed on the ITO transparent electrode film side of the PET film on which the ITO (indium oxide) transparent electrode film was formed on one side. The luminescent layer is obtained by coating a phosphor paste obtained by mixing the phosphor powder with the binder resin as described above by a binder ratio of 5:1 to a transparent electrode, and calcining the film after calcination. The film formation was carried out in such a manner that the thickness became about 60 μm. The dielectric layer is a dielectric paste in which barium titanate (BaTiO ₃ ) particles and a binder resin are mixed at a weight ratio of 3:1, and is applied onto a light-emitting layer, and calcined to form a film thickness after calcination. Film formation was carried out in a 20 μm manner. Finally, an Ag paste was applied onto the dielectric and calcined to form a back electrode, whereby the dispersion type EL device of Example 3 was obtained.

[Example 4]

The precursor of the ZnS phosphor is precipitated by liquid phase synthesis by using Calcination was carried out to obtain ZnS microcrystals having a particle diameter (D50) of about 10 μm. At this time, the coactivator is added with Al in a liquid phase, and the n-type ZnS is first made to occupy almost all of the crystal particles. Next, the crystal particles are washed with hydrochloric acid, washed with water, and dried at 100 ° C to 300 ° C to remove Al from the surface of the ZnS. The ZnS particles were placed in an aqueous CuCl solution and impregnated with Cu. Then, calcination is carried out at 100 ° C to 500 ° C, washed again with ammonia water, and dried to obtain a phosphor powder.

The dispersion-type EL element of Example 4 was produced in the same manner as in Example 3 except that the light-emitting layer containing the phosphor powder obtained as described above was provided.

[Comparative Example 2]

The precursor of the ZnS phosphor was precipitated by liquid phase synthesis, and by calcination, ZnS microcrystals having a particle diameter (D50) of about 10 μm were obtained. At this time, Cu as an activator and Al as a co-activator are added to the liquid phase, and after calcination, it is washed and dried to obtain a phosphor powder.

The dispersion-type EL element of Comparative Example 2 was produced in the same manner as in Example 3 except that the light-emitting layer containing the phosphor powder obtained as described above was provided.

<Lighting characteristics test>

The light-emitting characteristics of the dispersion-type EL elements of Examples 3 and 4 and Comparative Example 2 produced as described above were evaluated. The dispersion type EL element is driven by an alternating current of 10 kHz and an actual value of 215V. Table 2 summarizes the brightness and luminous efficiency at this time. In Examples 3 and 4, the brightness was about 3 times and the luminous efficiency was nearly 2 to 5 times as compared with the comparative example.

The reason why the luminescent properties of the examples and the comparative examples are significantly different can be estimated as follows. In Comparative Example 2, an activator and a co-activator were added when ZnS crystals were synthesized in the liquid phase. Therefore, the activator and the co-activator are more uniformly dispersed in the crystallization, and a clear pn junction is not formed. On the other hand, in the bulk (center) portion of the phosphor particles of Examples 3 and 4, an activator was disposed, and a co-activator was mainly distributed on the surface, so that a pn junction was formed at the interface, and it was estimated that it was used as a dispersion type EL. When the light body is used, the luminous efficiency is improved.

The description of the above embodiments is merely illustrative and should not be construed as limiting. The scope of the present invention is not limited to the above embodiments, but is shown in the scope of the patent application. In addition, all the modifications within the scope and scope of the invention are intended to be included within the scope of the invention.

Claims (19)

A method for producing a phosphor for a dispersion type EL, comprising adding an activator and a co-activator to a matrix particle; wherein the activator or the co-activator is impregnated into the precursor particles, and then calcined by the calcination The above activator or the above coactivator is added to the above parent particles. The method for producing a phosphor for a dispersion type EL according to the first aspect of the invention, further comprising: the first calcination step of calcining the precursor particles; and the first impregnation step, the step of performing the first calcination step The precursor particles are impregnated with an activator or a co-activator; and the second impregnation step is performed by impregnating the precursor particles after the first impregnation step with a co-activator or an activator; and finally calcining the second impregnation step The precursor particles after the step are calcined; and the washing step of washing the precursor particles after the final calcination step. The method for producing a phosphor for a dispersion type EL according to the first aspect of the invention, further comprising: a first calcination step of calcining the precursor particles; and an impregnation step of the parent particles after the first calcination step And simultaneously impregnating the activator and the co-activator; in the final calcining step, calcining the parent particles after the impregnation step is performed; and the washing step, washing the mother particles after the final calcination step. The method for producing a phosphor for a dispersion type EL according to the first aspect of the invention, comprising: a synthesis step of synthesizing a precursor particle in a liquid phase containing an activator or a coactivator; and an initial calcination step, The precursor particles obtained by the synthesis step are subjected to calcination; the impregnation step is performed to impregnate the precursor particles after the initial calcination step, impregnating a co-activator or an activator; and finally calcining the calcination of the precursor particles after the impregnation step is performed And a washing step of washing the precursor particles after the last calcination step. The method for producing a phosphor for a dispersion type EL according to the second aspect of the invention, further comprising: an intermediate calcination step of calcining the precursor particles after the first impregnation step. The method for producing a phosphor for a dispersion type EL according to claim 5, further comprising: a washing step of washing the precursor particles after the intermediate calcination step. The method for producing a phosphor for a dispersion type EL according to claim 3, further comprising: a washing step of washing the precursor particles after the first calcination step. The method for producing a phosphor for a dispersion type EL according to the sixth aspect of the invention, further comprising: a washing step of washing the precursor particles after the first calcination step. The method for producing a phosphor for a dispersion type EL according to the first aspect of the invention, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to the second aspect of the patent application, wherein The above parent particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to the third aspect of the invention, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to the fourth aspect of the invention, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to claim 5, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to claim 6, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to claim 7, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to the eighth aspect of the invention, wherein the precursor particles are ZnS particles. The method for producing a phosphor for a dispersion type EL according to any one of claims 9 to 16, wherein the activator is one or more elements selected from the group consisting of Group 11 or Group 15. The method for producing a phosphor for a dispersion type EL according to any one of claims 9 to 16, wherein the coactivator is one or more elements selected from Group 13 or Group 17 elements. The method for producing a phosphor for a dispersion type EL according to the seventeenth aspect of the invention, wherein the coactivator is one or more elements selected from the group consisting of Group 13 or Group 17.