WO2014021353A1

WO2014021353A1 - Fluorescent material, and light-emitting device

Info

Publication number: WO2014021353A1
Application number: PCT/JP2013/070667
Authority: WO
Inventors: 美史傳井; 誉史阿部; 佐藤　豊
Original assignee: 株式会社日本セラテック
Priority date: 2012-08-02
Filing date: 2013-07-30
Publication date: 2014-02-06
Also published as: JP2014043569A; TW201412940A

Abstract

[Problem] To provide a fluorescent material which can reduce the impact, on surrounding members, of the generation of hydrogen sulfide, and a light-emitting device using the fluorescent material. [Solution] The fluorescent material comprises a fluorescent particle (11) made from a sulfide-based fluorescent substance, and a coating layer (12) which is provided on the surface of the fluorescent particle (11) and which contains zinc oxide (ZnO). At normal temperature and pressure zinc oxide reacts readily with the hydrogen sulfide (H₂S) that is generated by the reaction between the fluorescent particle (11) and water or the like, and the zinc oxide is converted to zinc sulfide (ZnS) and water (H₂O) which have little impact on optical properties.

Description

Phosphor material and light emitting device

The present invention relates to a phosphor material including phosphor particles made of a sulfide-based phosphor and a light-emitting device using the phosphor material.

Currently, LED lamps are attracting attention as backlights for LCD TVs or as next-generation lighting. In order to make the LED lamp emit white light, the light emitted from the LED element itself is passed through a phosphor, such as red, blue, or green, or a kneaded lens, and the white light is obtained by superimposing the light emitted from the phosphor. There is a need. In recent years, in order to improve color rendering properties, sulfide-based phosphors containing sulfur have attracted attention. However, phosphors have a weak point in that their light emission characteristics deteriorate when exposed to moisture, heat, or ultraviolet rays. In particular, sulfide-based phosphors are chemically unstable, and hydrogen sulfide is generated by the reaction of the phosphor surface with water, which has a significant adverse effect on surrounding members. Therefore, there are very few cases that have been put to practical use. Therefore, in order to protect against these external causes, it has been proposed to form a coating layer on the surface of the phosphor particles (see, for example, Patent Document 1).

Japanese Patent Application No. 2010-248411

However, although the alteration of the phosphor particles itself can be suppressed to a minimum by forming the coating layer, it is not enough to suppress the influence of hydrogen sulfide, and the generated hydrogen sulfide causes surrounding members, for example, There was a problem that the reflector, the wiring, or the sealing resin deteriorated. In particular, when silver is used for the reflector, silver easily reacts with hydrogen sulfide, becomes silver sulfide, becomes blackened, and the reflectance is significantly reduced.

The present invention has been made based on such a problem, and an object of the present invention is to provide a phosphor material capable of reducing the influence of the generation of hydrogen sulfide on surrounding members and a light emitting device using the same. To do.

The phosphor material of the present invention contains phosphor particles made of sulfide phosphor and zinc oxide.

The light emitting device of the present invention includes the phosphor material of the present invention.

According to the phosphor material of the present invention, since zinc oxide is contained, hydrogen sulfide generated from the phosphor particles can be decomposed by reacting with zinc oxide to render it harmless. Therefore, the influence on the surrounding members due to the generation of hydrogen sulfide can be reduced, and deterioration of characteristics can be suppressed.

Zinc oxide may be included by providing a coating layer containing zinc oxide on the surface of the phosphor particles, or may be included by providing phosphor particles and auxiliary particles containing zinc oxide.

In particular, if the amount of the zinc oxide layer in the coating layer is set to 0.75 wt% or more and 30 wt% or less in terms of the weight ratio of zinc oxide to the weight of the phosphor particles, the zinc oxide layer is also included in the coating layer. If the thickness of the zinc oxide layer is 30 nm or more and 1 μm or less, the luminance maintenance ratio can be improved.

Furthermore, if the coating layer has a zinc oxide layer and a silicon dioxide layer, the luminance maintenance rate can be further improved, and the influence on surrounding members due to the generation of hydrogen sulfide can be further reduced. .

It is a schematic diagram showing the structure of the phosphor material which concerns on the 1st Embodiment of this invention. It is a figure showing the structure of the light-emitting device using the fluorescent substance material of FIG. It is a figure showing the structure of the light-emitting device using the phosphor material which concerns on the 2nd Embodiment of this invention. It is a figure showing the experimental apparatus used in the Example. FIG. 6 is a characteristic diagram showing a change over time in light emission luminance of Examples 1-1 to 1-3 and Comparative Example 1-1. FIG. 6 is a characteristic diagram showing a change with time in light emission luminance of Examples 1-1 and 2-1 and Comparative Examples 1-1 and 2-1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 schematically shows a phosphor material 10 according to a first embodiment of the present invention. The phosphor material 10 includes phosphor particles 11 made of a sulfide-based phosphor and a coating layer 12 provided on the surface of the phosphor particles 11.

Examples of the sulfide-based phosphor constituting the phosphor particles 11 include blue-based phosphors such as ZnS: Ag, Cl or BaAl ₂ S ₄ : Eu, ZnS: Cu, Al, or SrGa ₂ S ₄ : Eu. Green phosphor, yellow phosphor such as CaGa ₂ S ₄ : Eu, Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, CaS: Eu, SrS: Eu, or (Ca, Sr) S: Eu However, the sulfide-based phosphor of the present invention is not limited to those described above. The particle diameter of the phosphor particles 11 is basically not limited, but it is preferable that the average particle diameter is about 5 μm to 20 μm and the particle diameters are as uniform as possible. This is because the characteristics can be stabilized.

The coating layer 12 contains zinc oxide (ZnO). As shown in Chemical Formula 1, zinc oxide easily reacts with hydrogen sulfide (H ₂ S) generated when phosphor particles 11 react with water or the like at room temperature and normal pressure, and has optical properties and surrounding members. This is because it is converted into zinc sulfide (ZnS) and water (H ₂ O) that have a small effect.
ZnO + H ₂ S → ZnS + H ₂ O (Chemical Formula 1)

The covering layer 12 may be constituted by a single layer of a zinc oxide layer made of zinc oxide, but is preferably constituted by a plurality of layers obtained by laminating a zinc oxide layer and one or more other layers. By laminating with other layers, the deterioration of the phosphor particles 11 can be further suppressed, and the generation of hydrogen sulfide can be suppressed thereby.

As other layers, for example, magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), titanium oxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La) ₂ O ₃ ), cerium oxide (CeO ₂ ), gadolinium oxide (Gd ₂ O ₃ ), and a layer containing at least one selected from the group consisting of zirconium oxide (ZrO ₂ ). When the other layer contains two or more kinds of compounds, they may be mixed or combined in one layer, or a plurality of compounds may be laminated in layers. Among them, the other layer preferably contains silicon dioxide, and more preferably has a silicon dioxide layer made of silicon dioxide. This is because a higher effect can be obtained.

The thickness of the zinc oxide layer is preferably, for example, from 30 nm to 1 μm, more preferably from 100 nm to 500 nm. Further, the amount of zinc oxide in the coating layer 12 is preferably 0.75 wt% or more and 30 wt% or less, and 2.5 wt% or more and 15 wt% or less in terms of the weight ratio of zinc oxide to the weight of the phosphor particles 11. % Or less is more preferable. When the thickness of the zinc oxide layer is thin or the amount of zinc oxide is small, the effect of reducing the influence on the surrounding members due to the generation of hydrogen sulfide is small, and when the thickness of the zinc oxide layer is thick or the amount of zinc oxide is large, This is because the initial luminance is lowered and the luminance is deteriorated with time. The thickness of the other layer is preferably, for example, from 30 nm to 1 μm, and more preferably from 100 nm to 500 nm. This is because a higher effect can be obtained within this range.

The stacking order of the zinc oxide layer and other layers is not particularly limited. For example, the zinc oxide layer may be on the phosphor particle 11 side, the other layer may be on the phosphor particle 11 side, another layer may be inserted between the zinc oxide layers, and between the other layers. A zinc oxide layer may be inserted into the substrate.

In addition, you may comprise the coating layer 12 so that it may have a mixed layer or a composite layer containing a zinc oxide and another substance. Examples of the other substance include at least one selected from the group consisting of magnesium oxide, aluminum oxide, silicon dioxide, titanium oxide, yttrium oxide, lanthanum oxide, cerium oxide, gadolinium oxide, and zirconium oxide. Alternatively, a mixed layer or a composite layer containing zinc oxide and another substance and the above-described other layer may be stacked. Also in this case, the amount of zinc oxide in the coating layer 12 is preferably 0.75 wt% or more and 30 wt% or less in terms of the weight ratio of zinc oxide to the weight of the phosphor particles 11, and 2.5 wt% or more. More preferably, it is 15% by weight or less.

The phosphor material 10 is obtained, for example, by forming a coating layer 12 on the surface of the phosphor particles 11 by various methods. Specifically, for example, a sol-gel method or a method in which the fine particles constituting the coating layer 12 are attached to the surface of the phosphor particles 11 by various methods such as wet or dry methods.

FIG. 2 shows a configuration example of the light emitting device 20 using the phosphor material 10. In the light emitting device 20, a light emitting element 22 is mounted on a substrate 21, and the light emitting element 22 is electrically connected to a wiring 23 formed on the substrate 21 by a wire 24. The wiring 23 and the wire 24 are made of, for example, copper. Further, for example, a reflector frame 25 is formed around the light emitting element 22. On the inner surface of the reflector frame 25, that is, the surface on the light emitting element 22 side, a reflector 26 made of, for example, silver that reflects light from the light emitting element 22 is formed. A sealing layer 27 is formed on the light emitting element 22 so as to cover the light emitting element 22. The sealing layer 27 is made of, for example, a resin in which the phosphor material 10 is dispersed.

The light emitting element 22 is, for example, one that emits ultraviolet light, blue light, or green light as excitation light. As the phosphor material 10, for example, one that emits red light by excitation light emitted from the light emitting element 22, one that emits blue light, one that emits green light, one that emits yellow light, or the like is necessary. Depending on the mixture, they are used.

In such a light emitting device 20, the reflector 26, the wiring 23, the wire 24, the sealing layer 27, and the like are deteriorated by hydrogen sulfide generated from the phosphor particles 11 of the phosphor material 10. In particular, when the reflector 26 is made of silver, the reactivity between silver and hydrogen sulfide is high, so that the deterioration is significant. However, according to the present embodiment, since the coating layer 12 containing zinc oxide is formed on the surface of the phosphor particles 11, generation of hydrogen sulfide can be suppressed and deterioration can be suppressed. ing.

As described above, according to the present embodiment, since the coating layer 12 containing zinc oxide is provided, the hydrogen sulfide generated from the phosphor particles 11 can be decomposed by reacting with zinc oxide to be harmless. . Therefore, the influence on the surrounding members due to the generation of hydrogen sulfide can be reduced, and deterioration of characteristics can be suppressed. For example, when the phosphor material 10 according to the present embodiment is used in the light emitting device 20, the reflector 26, the wiring 23, the wire 24, the sealing layer 27, and the like are generated by hydrogen sulfide generated from the phosphor material 10. Deterioration can be suppressed, and the life can be extended.

In particular, if the amount of the zinc oxide layer in the coating layer 12 is 0.75 wt% or more and 30 wt% or less in terms of the weight ratio of zinc oxide to the weight of the phosphor particles 11, If a zinc oxide layer is provided and the thickness of the zinc oxide layer is 30 nm or more and 1 μm or less, the luminance maintenance ratio can be improved.

Further, if the coating layer 12 includes a zinc oxide layer and a silicon dioxide layer, the luminance maintenance rate can be further improved, and the influence on the surrounding members due to the generation of hydrogen sulfide can be reduced. it can.

(Second Embodiment)
FIG. 3 shows a configuration example of the light emitting device 40 using the phosphor material 30 according to the second embodiment of the present invention. The phosphor material 30 includes phosphor particles 31 made of sulfide phosphor and auxiliary particles 32 containing zinc oxide. The phosphor particles 31 have the same configuration as the phosphor particles 11 described in the first embodiment. The auxiliary particles 32 are, for example, decomposed by hydrogen sulfide generated by the reaction of the phosphor particles 31 with water or the like. As described in the first embodiment, the auxiliary particles 32 are made of zinc oxide contained in the auxiliary particles 32. It converts hydrogen sulfide into zinc sulfide and water. The particle diameter of the auxiliary particles 32 is basically not limited, but the average particle diameter is preferably about 30 nm to 5 μm.

The phosphor particles 31 are preferably provided with a coating layer (not shown) on the surface. The coating layer includes, for example, a layer containing at least one selected from the group consisting of zinc oxide, magnesium oxide, aluminum oxide, silicon dioxide, titanium oxide, yttrium oxide, lanthanum oxide, cerium oxide, gadolinium oxide, and zirconium oxide. Can be mentioned. When two or more kinds of compounds are included, they may be mixed or combined in one layer, or a plurality of compounds may be stacked in layers. Among these, it is more preferable to provide the coating layer 12 described in the first embodiment. This is because a higher effect can be obtained.

The light emitting device 40 according to the present embodiment has the same configuration as the light emitting device 20 according to the first embodiment, except that the configuration of the phosphor material 30 is different. Therefore, the same components as those of the light emitting device 20 according to the first embodiment are denoted by the reference numerals in which the tens place is changed to 4, and the detailed description thereof is omitted.

As described above, according to the present embodiment, since the auxiliary particles 32 containing zinc oxide are provided, the hydrogen sulfide generated from the phosphor particles 31 can be decomposed by reacting with zinc oxide and rendered harmless. . Therefore, similarly to the first embodiment, the influence on the surrounding members due to the generation of hydrogen sulfide can be reduced, and deterioration of characteristics can be suppressed.

(Examples 1-1 to 1-6)
Phosphors of Examples 1-1 to 1-6, in which a zinc oxide layer made of zinc oxide is formed as a coating layer 12 on the surface of phosphor particles 11 made of sulfide-based phosphor (Ca, Sr) S: Eu. Material 10 was obtained. The coating layer 12 was formed by applying a slurry in which fine particles of zinc oxide were dispersed in a solvent to the phosphor particles 11 and performing a heat treatment. At that time, the thickness of the coating layer 12 (that is, the zinc oxide layer) was changed by changing the amount of the zinc oxide fine particles dispersed in the solvent in Examples 1-1 to 1-6. The thickness of the coating layer 12 is about 200 nm in Example 1-1, about 500 nm in Example 1-2, about 1 μm in Example 1-3, about 100 nm in Example 1-4, and about 1 nm in Example 1-5. The thickness was 40 nm and Example 1-6 was about 20 nm. In addition, when the amount of the coating layer 12 (that is, the zinc oxide layer) is converted into the weight ratio of zinc oxide to the weight of the phosphor particles 11, Example 1-1 is about 5% by weight and Example 1-2 is about 15% by weight. %, Example 1-3 is about 30% by weight, Example 1-4 is about 2.5% by weight, Example 1-5 is about 1.0% by weight, and Example 1-6 is about 0.5% by weight. %Met.

As shown in FIG. 4, the obtained phosphor materials 10 of Examples 1-1 to 1-6 were housed in a sealed container 52 together with the silver plate 51, and an exposure test at 85 ° C. in a high-temperature and humid environment was conducted. . Water 53 was placed in the sealed container 52, and the phosphor material 10 and the silver plate 51 were disposed above the water 53 so as not to be immersed in the water 53. The change in reflectance with respect to the exposure time of the silver plate 51 was measured with a spectrophotometer every 30 minutes. As a judgment standard, if the measured reflectance of the silver plate 51 was 80% or more, the test was accepted, and when the reflectance was less than 80%, the reflectance of the silver plate 51 was considered to be significantly reduced, and the test was terminated. The obtained results are shown in Table 1. The reflectance is expressed as a relative value when a reference silver plate is prepared separately and the reflectance of the reference silver plate is 100.

As Comparative Example 1-1 with respect to Examples 1-1 to 1-6, a phosphor material in which a coating layer is not formed, that is, phosphor particles are prepared, and in the same manner as in Examples 1-1 to 1-6, A 85 ° C. high temperature and humidity environment exposure test was performed, and the change in reflectance of the silver plate 51 was examined. The same phosphor particles as in Examples 1-1 to 1-6 were used. The results of Comparative Example 1-1 are also shown in Table 1.

As shown in Table 1, in Comparative Example 1-1, the reflectance of the silver plate 51 decreased to 18.5% in 30 minutes, whereas in Example 1-1, 60 minutes passed. Even in the case of the silver plate 51, a reflectance of 91.7% was obtained. In Example 1-2, a reflectance of 100.4% was obtained even after 90 minutes. In Example 1-3, Even after 120 minutes, a reflectance of 93.5% was obtained. In Example 1-4, a reflectance of 101.8% was obtained even after 30 minutes. In Example 1-5, Even after 30 minutes, a reflectivity of 100.4% was obtained. Further, the surface of the silver plate 51 was blackened after 30 minutes in Comparative Example 1-1, blackened after 90 minutes in Example 1-1, and 120 minutes passed in Example 1-2. Blackening was observed later. In Example 1-3, blackening was observed after 150 minutes, and in Examples 1-4 and 1-5, blackening was observed after 60 minutes. In Example 1-6, blackening was observed after 30 minutes, but the reflectance of the silver plate 51 after 30 minutes was 44.7%, which is higher than that of Comparative Example 1-1. It was.

That is, it has been found that if the coating layer 12 containing zinc oxide is provided, the influence of the generation of hydrogen sulfide on the surrounding members such as the reflector 26 can be reduced, and deterioration of characteristics can be suppressed. . It was found that the effect was higher as the zinc oxide layer was thicker.

Separately, the phosphor material 10 of Examples 1-1 to 1-3 and the phosphor material of Comparative Example 1-1 were subjected to a high-temperature and high-humidity environment exposure test at 85 ° C. and 85% RH, and the luminance change with time. I investigated. The obtained results are shown in FIG. In FIG. 5, the vertical axis represents the relative luminance value when the initial luminance of Comparative Example 1-1 is set to 100.

As shown in FIG. 5, in Examples 1-1 to 1-3, the initial luminance was lower than that in Comparative Example 1-1, but according to Examples 1-1 and 1-2, Comparative Example Compared to 1-1, the luminance maintenance rate could be improved. That is, it was found that if the thickness of the zinc oxide layer is 500 nm or less, the luminance maintenance ratio can be improved and the initial luminance can be suppressed from being lowered.

Example 2-1
A phosphor material 10 was produced in the same manner as in Example 1-1 except that the coating layer 12 was a two-layer structure of a silicon dioxide layer made of silicon dioxide and a zinc oxide layer made of zinc oxide. The zinc oxide layer was formed on the silicon dioxide layer. The thickness of the silicon dioxide layer was about 300 nm, and the thickness of the zinc oxide layer was about 200 nm. Further, as Comparative Example 2-1 with respect to Example 2-1, the phosphor material 10 was produced in the same manner as Example 1-1 except that the coating layer was composed only of a silicon dioxide layer made of silicon dioxide. did. The thickness of the silicon dioxide layer was about 300 nm. The silicon dioxide layers of Example 2-1 and Comparative Example 2-1 are prepared by mixing phosphor particles 11 in a precursor solution containing silicon in which perhydropolysilazane and a solvent are mixed, drying, and heat-treating. Formed by.

The phosphor material 10 of Example 2-1 and Comparative Example 2-1 was also subjected to a high-temperature and humidity environment exposure test at 85 ° C. housed in a sealed container 52 together with the silver plate 51 in the same manner as in Example 1-1. A high-temperature and high-humidity environment exposure test at 85 ° C. and 85% RH was conducted. The obtained results are shown in Table 2 and FIG. 6 together with the results of Example 1-1 and Comparative example 1-1. The reflectance in Table 2 is expressed as a relative value when a standard silver plate is prepared separately and the reflectance of the standard silver plate is 100. In FIG. 6, the vertical axis represents a relative luminance value when the initial luminance of Comparative Example 1-1 is set to 100.

As shown in Table 2, according to Example 2-1, a reflectivity of 89.8% was obtained for the silver plate 51 even after 180 minutes had passed, and the characteristics were significantly higher than those of Example 1-1. Was able to improve. Further, as shown in FIG. 6, according to Example 2-1, the luminance maintenance ratio could be significantly improved as compared with Example 1-1. That is, if the coating layer 12 including the silicon dioxide layer and zinc oxide is provided, the influence of the generation of hydrogen sulfide on the surrounding members such as the reflector 26 can be reduced, and the luminance maintenance rate can be further increased. It has been found that it can be improved.

(Examples 3-1, 3-2, 4-1, 4-2, 5-1, 5-2)
As Examples 3-1, 4-1 and 5-1, a phosphor material 10 was produced in the same manner as in Example 1-1. That is, the coating layer 12 is composed of a zinc oxide layer, the thickness of the zinc oxide layer is 0.2 μm, and the amount of the coating layer 12 is about 5% by weight when converted to the weight ratio of zinc oxide to the weight of the phosphor particles 11. there were. Further, as Examples 3-2, 4-2, and 5-2, a phosphor material 10 was produced in the same manner as in Example 2-1. That is, the coating layer 12 was formed by laminating a zinc oxide layer on the silicon dioxide layer, and the silicon dioxide layer had a thickness of about 300 nm and the zinc oxide layer had a thickness of about 200 nm. Further, as Comparative Examples 3-1, 4-1 and 5-1 for this example, phosphor materials without a coating layer, that is, phosphor particles were prepared.

The produced phosphor materials 10 of Examples 3-1 and 3-2 and Comparative Example 3-1 were housed in a sealed container 52 together with the silver plate 51 in the same manner as in Example 1-1, and the temperature was set to 40 ° C. The changed high-temperature and humidity environment exposure test was performed, and the change in the reflectance of the silver plate 51 was examined. The phosphor materials 10 of Examples 4-1 and 4-2 and Comparative Example 4-1 were stored in a sealed container 52 together with the silver plate 51 in the same manner as in Example 1-1, and the temperature was changed to 60 ° C. A high temperature and humidity environment exposure test was conducted, and the change in reflectance of the silver plate 51 was examined. The phosphor materials 10 of Examples 5-1 and 5-2 and Comparative Example 5-1 are housed in the sealed container 52 together with the silver plate 51 in the same manner as in Example 1-1, and are stored in the sealed container 52. Conducted a high-temperature environment exposure test at 85 ° C. without adding water 53, and examined the change in reflectance of the silver plate 51. At that time, the inside of the sealed container 52 and all the contents including the phosphor material 10 and the silver plate 51 installed in the sealed container 52 are not specially dried in advance, and the adsorbed moisture is heated. By evaporating and diffusing inside the sealed container 52, an environment where a certain amount of moisture exists inside the sealed container 52 was obtained.

In each example and each comparative example, the reflectivity of the silver plate 51 is measured every 30 minutes, and when the measured reflectivity of the silver plate is 80% or more, it is considered acceptable, and when it becomes less than 80%. The test was terminated assuming that the reflectance of the silver plate 51 was significantly reduced. Tables 3 to 5 show the time when the reflectance of the silver plate 51 is less than 80% and the reflectance at that time. The reflectances in Tables 3 to 5 are expressed as relative values when a reference silver plate is prepared separately and the reflectance of the reference silver plate is 100.

As shown in Table 3, in Comparative Example 3-1, the reflectance of the silver plate 51 was less than 80% in 30 minutes, whereas in Example 3-1, the reflectance of the silver plate 51 was 80%. After 8 hours, it was less than 20% in Example 3-2. Further, as shown in Table 4, in Comparative Example 4-1, the reflectance of the silver plate 51 was less than 80% in 30 minutes, whereas in Example 4-1, the reflectance of the silver plate 51 was reduced. Was less than 80% after 4 hours, and in Example 4-2, it was after 8 hours. Further, as shown in Table 5, in Comparative Example 5-1, the reflectance of the silver plate 51 was less than 80% in 9 hours, whereas in Examples 5-1 and 5-2, 1000 hours. Even after the lapse of time, the reflectance was about 100%. In Comparative Example 5-1, the cause of the decrease in the reflectance despite the absence of water 53 in the sealed container 52 is that a certain amount of adsorbed moisture present in the sealed container 52 evaporates and diffuses. It is considered that the phosphor material reacts with the minute amount of adsorbed water to generate hydrogen sulfide, and the silver plate 51 is discolored.

That is, if the coating layer 12 containing zinc oxide is provided, the influence of the generation of hydrogen sulfide on the surrounding members such as the reflector 26 can be extremely reduced, and the silicon dioxide layer and the zinc oxide layer are provided. It was found that a higher effect can be obtained by doing so.

(Examples 6-1 and 6-2)
As Example 6-1, phosphor particles 31 made of sulfide-based phosphor (Ca, Sr) S: Eu and auxiliary particles 32 made of zinc oxide were mixed to obtain a phosphor material 30. As Example 6-2, the surface of phosphor particles 31 made of sulfide-based phosphor (Ca, Sr) S: Eu is formed with a zinc oxide layer made of zinc oxide as a coating layer, and made of zinc oxide. Auxiliary particles 32 were mixed to obtain a phosphor material 30. That is, in Example 6-2, a zinc oxide layer was formed as a coating layer on the surface of the phosphor particles 31 of Example 6-1. In Examples 6-1 and 6-2, the phosphor particles 31 and the auxiliary particles 32 were mixed at a mass ratio of 1: 1. The thickness of the coating layer in Example 6-2 was about 200 nm.

As Comparative Example 6-1 for Examples 6-1 and 6-2, a phosphor material not mixed with auxiliary particles, that is, phosphor particles was prepared. Examples 6-1 and 6-2 and Comparative Example 6-1 were subjected to a high-temperature and humid environment exposure test at 85 ° C. housed in a sealed container 52 together with the silver plate 51 in the same manner as in Example 1-1. The reflectivity of the silver plate 51 is measured every 30 minutes, and if the measured reflectivity of the silver plate is 80% or more, it is accepted, and when the reflectivity of the silver plate 51 is less than 80%, the reflectivity of the silver plate 51 is significantly reduced. The deemed test was completed. Table 6 shows the time when the reflectance of the silver plate 51 was less than 80% and the reflectance at that time. The reflectance in Table 6 is expressed as a relative value when a standard silver plate is prepared separately and the reflectance of the standard silver plate is 100. Table 6 also shows the results of Example 1-1 for reference.

As shown in Table 6, in Comparative Example 6-1, the reflectance of the silver plate 51 was less than 80% in 30 minutes, whereas in Example 6-1, the reflectance of the silver plate 51 was 80%. It was less than 60% after 60 minutes. That is, it was found that even if the zinc oxide auxiliary particles 32 are mixed with the phosphor particles 31, the influence of the generation of hydrogen sulfide on the surrounding members such as the reflector 26 can be reduced. Further, according to Example 6-2, the reflectivity of the silver plate 51 was less than 80% after 150 minutes, and the reflectivity was lower than that of Example 6-1 and Example 1-1. It was late. That is, it has been found that a higher effect can be obtained if a zinc oxide layer is formed as a coating layer on the surface of the phosphor particles 31 and the auxiliary particles 32 of zinc oxide are mixed and used.

The present invention has been described with reference to the embodiment and examples. However, the present invention is not limited to the above embodiment and example, and various modifications can be made. For example, in the above-described embodiment, the configuration of the light-emitting device 20 has been specifically described, but other configurations may be used. Moreover, in the said Example, although specifically investigated about the influence with respect to silver, the same effect can be acquired also about the influence which it gives to other members by generation | occurrence | production of hydrogen sulfide.

It can be used for light emitting devices such as LEDs.

DESCRIPTION OF

SYMBOLS

10,30 ... Phosphor material, 11,31 ... Phosphor particle, 12 ... Coating layer, 20,40 ... Light emitting device, 21,41 ... Substrate, 22,42 ... Light emitting element, 23,43 ... Wiring, 24,44 ... wire, 25, 45 ... reflector frame, 26, 46 ... reflector, 27, 47 ... sealing layer, 32 ... auxiliary particles

Claims

A phosphor material comprising phosphor particles made of sulfide phosphor and zinc oxide.
Phosphor particles comprising a sulfide-based phosphor;
The phosphor material according to claim 1, further comprising: a coating layer provided on a surface of the phosphor particles and containing zinc oxide.
3. The phosphor material according to claim 2, wherein the amount of the zinc oxide layer in the coating layer is 0.75 wt% or more and 30 wt% or less in terms of the weight ratio of zinc oxide to the weight of the phosphor particles. .
The phosphor material according to claim 2, wherein the coating layer has a zinc oxide layer made of zinc oxide.
The phosphor material according to claim 4, wherein the zinc oxide layer has a thickness of 30 nm to 1 μm.
The phosphor material according to claim 4, wherein the coating layer further includes a silicon dioxide layer made of silicon dioxide.
Phosphor particles comprising a sulfide-based phosphor;
The phosphor material according to claim 1, further comprising auxiliary particles containing zinc oxide.
A light-emitting device including a phosphor material,
The phosphor material includes a phosphor particle made of a sulfide-based phosphor and zinc oxide.
9. The light emitting device according to claim 8, wherein the phosphor material includes phosphor particles made of a sulfide-based phosphor, and a coating layer provided on a surface of the phosphor particles and containing zinc oxide. apparatus.
The light-emitting device according to claim 8, wherein the phosphor material includes phosphor particles made of a sulfide-based phosphor and auxiliary particles containing zinc oxide.
A light emitting element;
A reflector made of silver that reflects light from the light emitting element;
A sealing layer provided so as to cover the light emitting element,
The light emitting device according to claim 8, wherein the sealing layer includes the phosphor material.