JP2021008524A - Surface-treated phosphor and manufacturing method of the same, as well as light-emitting device - Google Patents

Abstract

To provide a manufacturing method of a surface-treated phosphor proving a light-emitting device having excellent brightness and reliability.SOLUTION: A manufacturing method of a surface-treated phosphor containing a process of surface treating a phosphor whose composition is expressed by the following formula (1) with alkoxysilane expressed by the following formula (2). K2MF6:Mn4+ (1) (In the formula, an element M is an element of one or more kinds selected from the group consisting of Si, Ge, Ti, Sn, Zr and Hf.) R1Si(OR2)3 (2) (In the formula, R1 is a substituted or non-substituted monovalent hydrocarbon group having 6 to 12 carbon atoms, R2 is a non-substituted monovalent hydrocarbon group.)SELECTED DRAWING: None

Description

The present invention relates to a surface-treated fluorescent substance, a method for producing the same, and a light emitting device.

In recent years, as a white light source, a white light emitting diode (white LED) which is a combination of a light emitting diode (LED) and a phosphor has been applied to a backlight light source of a display, a lighting device, and the like. Among them, white LEDs using InGaN-based blue LEDs as an excitation source are widely used.

The phosphor used for this white LED is required to be efficiently excited by the light emission of the blue LED and emit the fluorescence of visible light.
A typical example of the phosphor for a white LED is a Ce-activated yttrium aluminum garnet (YAG) phosphor that is efficiently excited by blue light and exhibits broad yellow emission. By combining the YAG phosphor alone with the blue LED, pseudo-white color can be obtained and light emission in a wide visible light region can be obtained. For this reason, white LEDs containing YAG phosphors are used for illumination and backlight sources.
However, since the white LED containing the YAG phosphor has a small amount of red component, there is a problem that the color rendering property is low in the lighting application and the color reproduction range is narrow in the backlight application.

Therefore, for the purpose of improving color rendering and color reproducibility, a white LED that combines a red phosphor that can be excited by a blue LED and a green phosphor such as Eu-activated β-sialon or orthosilicate has also been developed. There is.
Such a red phosphor for a white LED has high fluorescence conversion efficiency, little decrease in brightness at high temperature, and excellent chemical stability. Therefore, a nitride or oxynitride centered on Eu ²⁺ . Fluorescent materials are often used. Typical examples thereof include phosphors represented by the chemical formulas Sr ₂ Si ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ²⁺ , and (Ca, Sr) AlSiN ₃ : Eu ²⁺ .
However, the emission spectrum of the phosphor using Eu ²⁺ is broad and contains many emission components with low luminosity. Therefore, the brightness of the white LED of the YAG phosphor alone is high for the high fluorescence conversion efficiency. It will be greatly reduced compared to when it is used. In addition, since the phosphor used especially for display applications is required to be compatible with the color filter, it is not desirable to use a phosphor having a broad (unsharp) emission spectrum.

Eu ³⁺ and Mn ⁴⁺ are known as emission centers of red phosphors having a sharp emission spectrum. Among them, the fluoride phosphor (red phosphor) obtained by solidifying Mn ^{4+ in} a fluoride crystal such as K ₂ SiF ₆ and activating it is efficiently excited by blue light and has a half-value width. Since it has a narrow and sharp emission spectrum, excellent color rendering and color reproducibility can be realized without lowering the brightness of the white LED. Therefore, in recent years, studies on applying a K ₂ SiF ₆ : Mn ⁴⁺ phosphor to a white LED have been actively conducted (for example, Non-Patent Document 1).

On the other hand, Patent Document 1 discloses that the moisture resistance of the K ₂ SiF ₆ : Mn ⁴⁺ phosphor is improved by treating it with a surface treatment agent.

Japanese Patent No. 6090590

A. G. Paulusz, Journal of The Electrochemical Society, 1973, Vol. 120, No. 7, p. 942-947

In light emitting devices such as backlights and lighting of liquid crystal displays, improvement of light emitting characteristics is always required, and for that purpose, improvement of characteristics (particularly, brightness) of each member is required.
Further, in order to manufacture a light emitting device having higher brightness, a high current is recently applied to an LED chip, and a higher reliability than ever is required for a phosphor.
However, although the surface treatment method disclosed in Patent Document 1 can improve the moisture resistance of the phosphor, it cannot be said that the effect of improving the reliability of the light emitting device is sufficient.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface-treated phosphor and a method for producing the same, which provides a light emitting device having excellent brightness and reliability.
Another object of the present invention is to provide a light emitting device having excellent brightness and reliability.

As a result of diligent research to solve the above problems, the present inventors have surface-treated a specific phosphor with a specific alkoxysilane to provide a light-emitting device having excellent brightness and reliability. He found that he could obtain a body and completed the present invention.

That is, the present invention is a method for producing a surface-treated fluorescent substance, which comprises a step of surface-treating a fluorescent substance having a composition represented by the following formula (1) with an alkoxysilane represented by the following formula (2).
K ₂ MF ₆ : Mn ⁴⁺ ... (1)
(In the formula, the element M is one or more elements selected from the group consisting of Si, Ge, Ti, Sn, Zr and Hf.)
R ¹ Si (OR ² ) ₃ ... (2)
(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 12 carbon atoms, and R ² is an unsubstituted monovalent hydrocarbon group.)

Further, the present invention is a surface-treated fluorescent substance having a surface-treated portion of alkoxysilane represented by the following formula (2) on the surface of the phosphor having a composition represented by the following formula (1).
K ₂ MF ₆ : Mn ⁴⁺ ... (1)
(In the formula, the element M is one or more elements selected from the group consisting of Si, Ge, Ti, Sn, Zr and Hf.)
R ¹ Si (OR ² ) ₃ ... (2)
(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 12 carbon atoms, and R ² is an unsubstituted monovalent hydrocarbon group.)

Further, the present invention is a light emitting device including the above-mentioned surface-treated phosphor and a light emitting light source having a peak wavelength of 420 nm to 480 nm.

According to the present invention, it is possible to provide a surface-treated phosphor and a method for producing the same, which provide a light emitting device having excellent brightness and reliability.
Further, according to the present invention, it is possible to provide a light emitting device having excellent brightness and reliability.

It is an excitation / fluorescence spectrum of the phosphor obtained in Comparative Example 1. It is an X-ray diffraction pattern of the phosphor obtained in Comparative Example 1.

Unless otherwise specified in the present specification, when a numerical range is indicated, its upper limit value and lower limit value are included.

The method for producing a surface-treated fluorescent substance of the present invention includes a step of surface-treating the fluorescent substance with alkoxysilane.
Here, the term "surface-treated fluorescent substance" as used herein means a fluorescent substance that has undergone surface treatment, specifically, a fluorescent substance that has a surface-treated portion on its surface. The surface treatment portion may cover the entire surface of the phosphor, or may cover a part of the surface of the phosphor.

The phosphor used in the present invention is represented by the following formula (1).
K ₂ MF ₆ : Mn ⁴⁺ ... (1)
In formula (1), the element M is one or more tetravalents selected from the group consisting of Si (silicon), Ge (germanium), Ti (titanium), Sn (tin), Zr (zirconium) and Hf (hafnium). It is an element of. Among them, the element M is preferably Si from the viewpoint of chemical stability.

The fluorophore used in the present invention may be a single species or a mixture of two or more kinds of phosphors having different compositions, but from the viewpoint of chemical stability, fluorescence in which the element M is Si. It is preferably a body (single species). When a mixture of two or more kinds of phosphors is used, it is preferable to contain at least a phosphor in which the element M is Si. Specifically, it may be a mixture of a phosphor in which the element M is Si and a phosphor selected in the group in which the element M is Ge, Ti, Sn, Zr and Hf. Further, in the case of a mixture of two or more kinds of phosphors, it is preferable that the proportion of the phosphor in which the element M is Si in the mixture is high from the viewpoint of chemical stability.

The method for producing the phosphor used in the present invention is not particularly limited, and a conventionally known method can be used. For example, a method of precipitating a phosphor can be used by introducing a water-soluble organic solvent as a poor solvent into a reaction solution in which all the constituent elements of the phosphor are dissolved.

The alkoxysilane used in the present invention is represented by the following formula (2).
R ¹ Si (OR ² ) ₃ ... (2)
In the formula (2), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 12 carbon atoms, preferably 8 to 10, and R ² is an unsubstituted monovalent hydrocarbon group.

The substituted or unsubstituted monovalent hydrocarbon group of R ¹ is not particularly limited as long as the number of carbon atoms is within the above range, and may be, for example, a saturated aliphatic group such as an alkyl group or an unsaturated aliphatic group. .. Further, in these aliphatic groups, a part or all of hydrogen atoms may be substituted with fluorine atoms, amino groups, or other groups. If the number of carbon atoms in R ¹ is less than 6, it is not possible to sufficiently impart hydrophobicity to the phosphor. On the other hand, when the number of carbon atoms of R ¹ exceeds 12, the hydrophobic effect is sufficient, but the affinity with the resin (particularly, the silicone resin generally used for white LEDs) is lowered. As a result, the adhesion between the phosphor and the resin is lowered, so that the brightness of the light emitting device is lowered, and the distance between the phosphor and the resin is easily peeled off, so that the reliability of the light emitting device is lowered.

The unsubstituted monovalent hydrocarbon group of R ² is not particularly limited, and may be a saturated aliphatic group such as an alkyl group. Further, the unsubstituted monovalent hydrocarbon group of R ² is preferably a methyl group or an ethyl group, more preferably a methyl group, because the hydrolysis / condensation reaction of the alkoxy group may be delayed when the number of carbon atoms is large. Is.

Examples of the alkoxysilane represented by the above formula (2) include decyltrimethoxysilane, dodecyltrimethoxysilane, hexyltrimethoxysilane, triethoxy-1H, 1H, 2H, 2H-tridecafluoro-n-octylsilane, and the like. Examples thereof include trimethoxy (7-octen-1-yl) silane. A single type of alkoxysilane may be used, but two or more types may be used in combination.

The surface treatment method for the phosphor using alkoxysilane is not particularly limited, and can be performed according to a known method. For example, a method of directly spraying an alkoxysilane on a phosphor, a stirring / mixing method of processing using a stirring device having a shearing force, a dry method of processing using a ball mill, a mixer, etc., a wet method of treating with water or an organic solvent. A method or the like can be used. In the stirring and mixing method, it is important to control the shearing force to the extent that the phosphor is not destroyed. Further, the in-system temperature or the drying temperature after the treatment in the dry method is appropriately determined in a region where thermal decomposition does not occur depending on the type of the surface treatment agent, but it is preferably carried out at 80 to 150 ° C.

The amount of alkoxysilane used in the surface treatment is not particularly limited, but is preferably 10 to 70 times the required amount calculated from the specific surface area of the phosphor.
Here, in the present specification, the "required amount calculated from the specific surface area of the phosphor" is the minimum amount required to cover the entire surface of the phosphor with alkoxysilane (surface treatment unit), and is fluorescent. It can be calculated from the specific surface area of the body (m ² / g). Specifically, the required amount of alkoxysilane is expressed by the following formula.
Required amount of alkoxysilane = mass of phosphor (g) x specific surface area of phosphor (m ² / g) / minimum coverage area of alkoxysilane (m ² / g)
The minimum coverage area of alkoxysilane is represented by the following formula.
Minimum coverage area of alkoxysilane = 6.02 × 10 ²³ × 13 × 10 ^-20 / Molecular weight of alkoxysilane

A typical example of surface modification of alkoxysilane to a phosphor is a dehydration condensation reaction with a hydroxyl group existing on the surface of the phosphor, but the phosphor used in the present invention has few hydroxyl groups on the surface. Therefore, in the present invention, in order to sufficiently carry out the reaction, it is preferable that the amount of alkoxysilane used is 10 times or more the required amount calculated from the specific surface area of the phosphor. On the other hand, if the amount of the alkoxysilane used is too large, the alkoxy groups in the alkoxysilane may be polymerized in a disorderly manner, and the affinity with the resin may be lowered as compared with the case where the surface treatment is not performed. As a result, the adhesion between the phosphor and the resin is lowered, so that the brightness of the light emitting device is lowered, and the distance between the phosphor and the resin is easily peeled off, so that the reliability of the light emitting device is lowered. Therefore, it is preferable that the amount of alkoxysilane used is 70 times or less the required amount calculated from the specific surface area of the phosphor.

The mass increase rate of the phosphor due to the surface treatment is preferably 0.03% to 1.00%. When the mass increase rate of the surface-treated phosphor is less than 0.03%, the effect of improving the hydrophobicity by the surface treatment may not be sufficient. On the other hand, if the mass increase rate of the surface-treated phosphor exceeds 1.00%, the alkoxy groups in the alkoxysilane may polymerize in a disorderly manner, and the affinity with the resin may decrease.
Here, in the present specification, the "mass increase rate of the surface-treated fluorescent substance with respect to the fluorescent substance" refers to the mass increase rate of the surface-treated fluorescent substance with respect to the fluorescent substance (unsurface-treated fluorescent substance) which has not been surface-treated with alkoxysilane. means.

The phosphor (surface-treated phosphor) whose surface has been surface-treated as described above has a surface-treated portion of alkoxysilane on its surface.
Since this surface-treated fluorescent substance is produced by surface-treating a specific phosphor with a specific alkoxysilane, it is possible to provide a light emitting device having excellent brightness and reliability.

The light emitting device of the present invention includes the above-mentioned surface-treated phosphor and a light emitting source having a peak wavelength of 420 nm to 480 nm. Since this light emitting device includes a surface-treated phosphor having the above characteristics, it is excellent in brightness and reliability. Further, by setting the peak wavelength of the light emitting light source to 420 nm to 480 nm, Mn ⁴⁺ , which is the light emitting center of the surface-treated phosphor, can be efficiently excited and can be used as blue light of the light emitting device.

The light emitting device of the present invention may further include a phosphor (hereinafter, referred to as “green phosphor”) that emits green light having a peak wavelength of 510 nm to 550 nm when receiving excitation light having a wavelength of 455 nm. The green phosphor may be of a single species, but may be of two or more. The light emitting device of the present invention having such a configuration can obtain white light by a combination of the surface-treated phosphor of the present invention that emits red light, a light emitting device that produces blue light, and a green phosphor that emits green light. At the same time, it is possible to obtain light emission in various color ranges by changing the mixing ratio of these three colors. In particular, it is preferable to use an EU-activated β-sialone phosphor as the green phosphor because a light emitting device having a high color gamut can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as it does not deviate from the gist thereof.
<Comparative example 1>
At room temperature, 600 mL of hydrofluoric acid with a concentration of 55% by mass was placed in a fluororesin beaker with a capacity of 1500 mL, and 76.50 g of potassium bifluoride powder (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) and manganese hexafluoride were added. An aqueous solution was prepared by sequentially dissolving 3.30 g of potassium acid powder. 20.70 g of silica powder (manufactured by Denka, FB-50R, amorphous, average particle size 55 μm) was added to this aqueous solution. When the silica powder was added to the aqueous solution, the temperature of the aqueous solution increased due to the generation of heat of solution. The solution temperature reached the maximum temperature about 3 minutes after the addition of the silica powder, and then the solution temperature decreased because the dissolution of the silica powder was completed. It was visually confirmed that yellow powder began to be formed in the aqueous solution immediately after the addition of the silica powder.
After the silica powder was completely dissolved, the aqueous solution was stirred for a while to complete the precipitation of the yellow powder. Then, the aqueous solution was allowed to stand to precipitate the solid content. After confirming the precipitation, the supernatant is removed, the yellow powder is washed with hydrofluoric acid and methanol having a concentration of 20% by mass, and the yellow powder is further filtered to separate and recover the solid content, and the residual methanol is further dried. Was removed by evaporation. After the drying treatment, a nylon sieve having a mesh size of 75 μm was used, and only the yellow powder that had passed through the sieve was classified and recovered to finally obtain 59.43 g of yellow powder (fluorescent substance).

<Confirmation of emission spectrum>
The excitation / fluorescence spectrum of the phosphor of Comparative Example 1 was measured using a spectrofluorescence meter (F-7000, manufactured by Hitachi High-Technologies Corporation). The obtained spectrum is shown in FIG. As a result, it was confirmed that the phosphor of Comparative Example 1 exhibited red emission at 632 nm by being excited with blue light at 455 nm.

<Confirmation of mother crystal of yellow powder by crystal phase measurement>
The X-ray diffraction pattern of the phosphor of Comparative Example 1 was measured using an X-ray diffractometer (manufactured by Rigaku Co., Ltd., trade name Ultima4, using CuKα tube). The obtained X-ray diffraction pattern is shown in FIG. As a result, since the X-ray diffraction pattern of the phosphor of Comparative Example 1 was the same as that of the K ₂ SiF ₆ crystal, it was confirmed that K ₂ SiF ₆ : Mn could be synthesized in a single phase.

<Specific surface area measurement>
The specific surface area of the phosphor of Comparative Example 1 was measured by the multipoint method of Kr gas adsorption using a specific surface area measuring device (3Flex manufactured by Micromeritics Co., Ltd.). The specific surface area of the measurement sample was measured after degassing under reduced pressure at 200 ° C. for 15 hours in advance. As a result, the specific surface area of the phosphor was 0.21 m ² / g.

<Example 1>
40.0 g of the phosphor of Comparative Example 1 was placed in a bag, and decyltrimethoxysilane (in formula (2), R ¹ is (CH ₂ ) ₉ CH ₃ and R ² is CH ₃ ; manufactured by Shin-Etsu Chemical Co., Ltd.). Was further added in an amount of 0.8 g so as to be 28 times the required amount calculated from the specific surface area of the phosphor, and mixed in the bag. Then, it was dried at 100 degreeC for 8 hours to obtain 39.8 g of a surface-treated fluorescent substance.

<Examples 2 to 3>
A surface-treated fluorophore was obtained in the same manner as in Example 1 except that the type of alkoxysilane was changed.
As the alkoxysilane, the following was used.
Example 2: Dodecyltrimethoxysilane (in formula (2), R ¹ is (CH ₂ ) ₁₁ CH ₃ and R ² is CH ₃ ; manufactured by Tokyo Chemical Industry Co., Ltd.).
Example 3: Hexyltrimethoxysilane (in formula (2), R ¹ is (CH ₂ ) ₅ CH ₃ and R ² is CH ₃ ; manufactured by Shin-Etsu Chemical Co., Ltd.)
Since the minimum coating area (m ² / g) of the alkoxysilane changes when the type of the alkoxysilane used changes, the amount of the alkoxysilane used is also adjusted in consideration of the value.

<Examples 4 to 7>
A surface-treated fluorophore was obtained in the same manner as in Example 1 except that the amount of alkoxysilane used was changed as shown in Table 1.
<Comparative Examples 2 to 4>
A surface-treated fluorophore was obtained in the same manner as in Example 1 except that the type of alkoxysilane was changed.
As the alkoxysilane, the following was used.
Comparative Example 2: Methyltrimethoxysilane (in formula (2), R ¹ is CH ₃ and R ² is CH ₃ ; manufactured by Shin-Etsu Chemical Co., Ltd.).
Comparative Example 3: n-propyltrimethoxysilane (in formula (2), R ¹ is (CH ₂ ) ₂ CH ₃ and R ² is CH ₃ ; manufactured by Shin-Etsu Chemical Co., Ltd.)
Comparative Example 4: Hexadecyltrimethoxysilane (in formula (2), R ¹ is (CH ₂ ) ₁₅ CH ₃ and R ² is CH ₃ ; manufactured by Tokyo Chemical Industry Co., Ltd.)

<Evaluation of mass increase rate of surface-treated phosphor>
The mass increase rate of each surface-treated fluorescent substance with respect to the unsurface-treated fluorescent substance obtained by drying 40.0 g of the fluorescent substance of Comparative Example 1 at 100 ° C. for 8 hours was calculated. Specifically, the mass increase rate was calculated based on the following formula.
Mass increase rate of surface-treated fluorophore = (mass of surface-treated fluorophore-mass of unsurface-treated fluorophore) / mass of unsurface-treated fluorophore x 100
The above evaluation results are shown in Table 1.

Next, the following evaluations were carried out using the surface-treated fluorescent materials obtained in Examples 1 to 7 and Comparative Examples 2 to 4 and the unsurface-treated fluorescent materials of Comparative Example 1.

<Total luminous flux measurement>
A surface-treated fluorescent substance or a fluorescent substance was added to a silicone resin together with a β-sialon green fluorescent substance (manufactured by Denka Co., Ltd., trade name GR-MW540K; peak wavelength 545 nm), and defoamed and kneaded. This kneaded product was potted in a surface mount type package to which a blue LED element having a peak wavelength of 450 nm was bonded, and further thermoset to produce a white LED. Here, the addition amount ratio of the surface-treated phosphor or the phosphor to the β-sialon green phosphor is such that the chromaticity coordinates (x, y) of the white LED become (0.280, 0.270) when the white LED emits light. Adjusted to.
Next, the total luminous flux when the produced white LED was energized was measured by a total luminous flux measuring device manufactured by Otsuka Electronics Co., Ltd. (a device combining a 300 mm diameter integrating hemisphere and a spectrophotometer / MCPD-9800). This measurement was performed on five white LEDs having a chromaticity x in the range of 0.275 to 0.284 and a chromaticity y in the range of 0.265 to 0.274, and the average value thereof was used as the measured value. .. Further, this evaluation result was a relative evaluation when the average value of the total luminous flux of the white LED produced by using the phosphor of Comparative Example 1 was set to 100%.

<Reliability test>
A test was conducted in which five white LEDs produced by total luminous flux measurement were energized and lit at 400 mA for 1000 hours in a constant temperature and humidity chamber (SH-642 manufactured by ESPEC) at a temperature of 85 ° C and a relative humidity of 85%. The deviation (Δx) of the chromaticity x and the reduction rate of the total luminous flux after 1000 hours from the above were determined. This evaluation was also performed on 5 white LEDs, and the average value thereof was used as the measurement result.
The results of each of the above measurements are shown in Table 2.

As shown in Table 2, the white LED produced by using the surface-treated phosphors of Examples 1 to 7 uses the unsurface-treated phosphor of Comparative Example 1 and the surface-treated phosphor of Comparative Examples 2 to 4. Compared with the manufactured white LED, the total luminous flux was high, and the deviation (Δx) of the chromaticity x and the reduction rate of the total luminous flux were small.

As can be seen from the above results, according to the present invention, it is possible to provide a surface-treated phosphor and a method for producing the same, which provides a light emitting device having excellent brightness and reliability. Further, according to the present invention, it is possible to provide a light emitting device having excellent brightness and reliability.

Since the surface-treated phosphor of the present invention can be suitably used as a red phosphor for white LEDs using blue light as a light source, it is suitable for use in a light emitting device such as a lighting fixture or an image display device.

Claims (11)

A method for producing a surface-treated fluorescent substance, which comprises a step of surface-treating a fluorescent substance having a composition represented by the following formula (1) with an alkoxysilane represented by the following formula (2).
K ₂ MF ₆ : Mn ⁴⁺ ... (1)
(In the formula, the element M is one or more elements selected from the group consisting of Si, Ge, Ti, Sn, Zr and Hf.)
R ¹ Si (OR ² ) ₃ ... (2)
(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 12 carbon atoms, and R ² is an unsubstituted monovalent hydrocarbon group.) The method for producing a surface-treated phosphor according to claim 1, wherein the element M is Si. The method for producing a surface-treated fluorescent substance according to claim 1 or 2, wherein R ² is a methyl group. The surface treatment fluorescence according to any one of claims 1 to 3, wherein the surface treatment is performed using an amount of alkoxysilane 10 to 70 times the required amount calculated from the specific surface area of the phosphor. How to make a body. The method for producing a surface-treated fluorescent substance according to any one of claims 1 to 4, wherein the mass increase rate of the surface-treated fluorescent substance with respect to the fluorescent substance is 0.03% to 1.00%. A surface-treated fluorescent substance having a surface-treated portion of alkoxysilane represented by the following formula (2) on the surface of the phosphor having a composition represented by the following formula (1).
K ₂ MF ₆ : Mn ⁴⁺ ... (1)
(In the formula, the element M is one or more elements selected from the group consisting of Si, Ge, Ti, Sn, Zr and Hf.)
R ¹ Si (OR ² ) ₃ ... (2)
(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 12 carbon atoms, and R ² is an unsubstituted monovalent hydrocarbon group.) The surface-treated fluorescent substance according to claim 6, wherein the element M is Si. The surface-treated fluorophore according to claim 6 or 7, wherein R ² is a methyl group. A light emitting device including the surface-treated phosphor according to any one of claims 6 to 8 and a light emitting light source having a peak wavelength of 420 nm to 480 nm. The light emitting device according to claim 9, further comprising a phosphor that emits green light having a peak wavelength of 510 nm to 550 nm when the light emitting device receives excitation light having a wavelength of 455 nm. The light emitting device according to claim 10, wherein the phosphor that emits green light is an EU-activated β-sialon phosphor.