TWI656194B - Fluoride phosphor, method of manufacturing the same, and semiconductor light emitting device - Google Patents

Abstract

The present invention provides a red luminescent fluoride phosphor excellent in water resistance.

A fluoride phosphor having at least a rare earth element fluorine compound on the surface of a fluoride particle represented by the general formula A ₂ MF ₆ : Mn. In the formula, M is at least one metal element selected from cerium (Si), titanium (Ti), and cerium (Ge), and A is at least one alkali metal element selected from sodium (Na) and potassium (K). It is a phosphor which has improved water resistance and is excellent in long-term stability, and a semiconductor light-emitting device using the same.

Description

Fluoride phosphor, method of manufacturing the same, and semiconductor light emitting device

The present invention relates to a fluoride phosphor and a method of producing the same. Further, the present invention relates to a semiconductor light-emitting device using the fluoride phosphor.

In the past, a light source that absorbs blue light or ultraviolet light and converts it into a long-wavelength visible light such as red or yellow or green, and combines the phosphor to obtain visible light such as white is A known.

As the light source of visible light or ultraviolet light in the short-wavelength region, a semiconductor light-emitting element such as a gallium nitride-based blue light-emitting diode or the like is used. Further, in combination with a phosphor of a wavelength converting material, a semiconductor light emitting device is constructed. This semiconductor light-emitting device has a feature of emitting visible light such as white, and has low power consumption and long life. In recent years, it has attracted attention as a light-emitting source such as an image display device or an illumination device.

A semiconductor light-emitting device that obtains white light is known to have a combination of a semiconductor light-emitting element that emits blue light and a phosphor that emits yellow light by wavelength conversion, or a combination of a semiconductor light-emitting element that emits blue light, and wavelength-converted blue light. a red-emitting phosphor and a green-emitting fluorescent Constructed as a body. Further, a semiconductor light-emitting device that emits ultraviolet light and three kinds of phosphors that emit ultraviolet light, green light, and blue light by wavelength conversion are known.

Using the semiconductor light-emitting device constructed as described above as an image display When the light source of the display device is used for backlighting of a liquid crystal display, for example, in order to efficiently reproduce a wide range of colors on a chromaticity coordinate, each of the phosphors preferably has a high light emission luminance and is excellent in color purity. Furthermore, it is required to conform to the combination of the color filters of the liquid crystal display, and a phosphor having a narrow half-value width of the luminescence peak is required.

A red-emitting phosphor having such a characteristic is known as a fluoride phosphor having a composition such as K ₂ TiF ₆ :Mn (see, for example, Patent Document 1). Further, a fluoride phosphor having a composition of K ₂ SiF ₆ : Mn is also known (see, for example, Patent Document 2).

Since the above-mentioned fluoride phosphor has a narrow half value of light emission peak and high color purity, it is suitable for backlight use of a liquid crystal display, and is expected to be put into practical use. However, the above-mentioned fluoride phosphor has insufficient water resistance and has a long-term reliability problem. In order to solve this problem, for example, a method of forming an alkaline earth metal fluoride on the surface of a fluoride phosphor has been proposed (see Patent Document 3). With this method, water resistance is still insufficient, and it is desired to have high water resistance. Fluoride phosphor.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2009-528429

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-209311

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2015-044951

The present invention has been made in view of the problem of the water resistance of the above-mentioned fluoride phosphor, and provides a red luminescent fluoride phosphor having higher water resistance. Further, the present invention provides a semiconductor light-emitting device excellent in long-term stability.

The present inventors reviewed the results of various methods for improving water resistance, and found a fluoride phosphor disclosed below and a method for producing the same.

The fluoride phosphor of the first aspect of the invention is characterized in that it has at least a rare earth element fluorine compound on the surface of the fluoride particles represented by the general formula A ₂ MF ₆ : Mn. In the formula, M is at least one metal element selected from cerium (Si), titanium (Ti), and cerium (Ge), and A is at least one alkali metal element selected from sodium (Na) and potassium (K). The rare earth element fluorine compound is preferably made of lanthanum (La), cerium (Ce), praseodymium (Pr), strontium (Nd), strontium (Sm), strontium (Eu), strontium (Gd), strontium (Tb), strontium. A fluorine compound of at least one rare earth element selected from (Dy), ruthenium (Ho), osmium (Tm), yttrium (Yb), and lanthanum (Lu). Fluoride phosphors having high water resistance are obtained by having a rare earth element fluorine compound on the surface of the fluoride particles.

The method for producing a fluoride phosphor according to the second aspect of the invention is characterized in that the fluoride particles represented by the general formula A ₂ MF ₆ : Mn are brought into contact with a solution containing a rare earth element ion and a reducing agent, and the fluoride particles are further contained. The step of forming a rare earth element fluorine compound on the surface. In the formula, M is at least one metal element selected from cerium (Si), titanium (Ti), and cerium (Ge), and A is at least one alkali metal element selected from sodium (Na) and potassium (K). The rare earth element ions are preferably composed of lanthanum (La), cerium (Ce), praseodymium (Pr), cerium (Nd), cerium (Sm), cerium (Eu), cerium (Gd), cerium (Tb), cerium ( An ion of at least one rare earth element selected from Dy), ruthenium (Ho), osmium (Tm), yttrium (Yb), and lanthanum (Lu). According to the above production method, a fluoride phosphor having high water resistance can be produced.

The semiconductor light-emitting device of the third aspect of the invention is characterized by comprising at least a semiconductor light-emitting device, a fluoride phosphor of the first invention, or a fluoride phosphor obtained by the method of the second invention. By having a fluoride phosphor having high water resistance, the light-emitting peak of red light has a half-value width and a high color purity, and has high long-term stability, so that it is suitable for backlight use of liquid crystal displays. An excellent semiconductor light emitting device.

According to the present invention, a red luminescent fluoride phosphor having high water resistance and excellent long-term stability can be obtained. Further, a semiconductor light-emitting device having high purity of red color and excellent long-term stability can be obtained.

11‧‧‧Semiconductor light-emitting elements

12‧‧‧Adhesive

13a‧‧‧P type electrode

14a‧‧‧N type electrode

15a‧‧‧Metal wire

15b‧‧‧Metal wire

16‧‧‧Printed circuit board

16a‧‧‧Electrode

16b‧‧‧Electrode

32‧‧‧Molded resin

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a powder X-ray diffraction pattern of a fluoride phosphor of Examples and Comparative Examples of the present invention.

Figure 2 is a cross-sectional view showing a semiconductor light emitting device according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a fluoride phosphor will be described as An embodiment of the invention. These manufacturing methods are illustrative of the embodiments of the present invention and are not intended to limit the present invention.

The method for producing a phosphor of the present invention roughly includes a step of producing a phosphor core particle and two steps of a surface treatment step of the obtained phosphor core particle.

(Step of producing phosphor core particles)

The phosphor core particles of the fluoride phosphor of the present invention are represented by a formula of A ₂ MF ₆ : Mn, wherein M is at least one selected from the group consisting of ruthenium (Si), titanium (Ti), and ruthenium (Ge). The metal element, A, is at least one alkali metal element selected from sodium (Na) and potassium (K). The phosphor core particles were produced as follows. That is, in a liquid medium containing hydrogen fluoride (HF), at least a fluoride containing a metal element represented by M, a fluoride containing manganese (Mn), and a fluoride containing an alkali metal element represented by A are reacted. And making. For example, a fluorinated substance containing Mn is dissolved in a hydrofluoric acid solution, and a fluoride containing a metal element represented by M is added as a first solution to dissolve a fluoride containing an alkali metal element represented by A in hydrogen. The fluoro acid solution is used as the second solution. The second solution is, for example, added dropwise to the first solution, and the resulting precipitate is separated by filtration or the like, and washed and dried to obtain the desired fluoride phosphor core particles. Further, the order or combination in which the respective fluorides are dissolved is not limited to the above examples.

As the fluoride containing Mn, for example, Na ₂ MnF ₆ or K ₂ MnF ₆ or the like can be used. For the fluoride containing a metal element represented by M, for example, when Si is selected as M, H ₂ SiF ₆ , K ₂ SiF ₆ , Na ₂ SiF ₆ , (NH ₄ ) ₂ SiF ₆ or the like can be used. For the fluoride containing the alkali metal element represented by A, for example, KF, KHF ₂ , NaF, NaHF ₂ or the like can be used.

The amount of each fluoride used may be an amount corresponding to the composition of the target fluoride phosphor core particles. Further, it is also preferred to carry out the reaction using an excessive amount of an alkali metal element.

The above-mentioned precipitate obtained by filtration may be washed with a solvent such as ethanol, water, acetone or isopropyl alcohol. Drying is only required to evaporate the water adhering to the precipitate, and the drying temperature, drying time, and the like can be appropriately selected.

A method for producing a fluoride phosphor core particle described in Patent Document 2 and Patent Document 3 can be used together with the above.

(Surface treatment step of fluoride phosphor core particles)

After the fluoride phosphor core particles obtained above are brought into contact with a solution containing at least a rare earth element ion and a reducing agent to be surface-treated, the surface of the phosphor core particles having a rare earth element fluorine compound is obtained by washing and drying. The fluoride phosphor of the present invention.

The rare earth element may be selected from the group consisting of lanthanum (La), cerium (Ce), praseodymium (Pr), cerium (Nd), cerium (Sm), cerium (Eu), cerium (Gd), cerium (Tb), and dysprosium (Dy). , 鈥 (Ho), 銩 (Tm), 镱 (Yb) and 镏 (Lu). As the ion source of the rare earth elements, a nitrate (for example, La(NO ₃ ) ₃ , Ce(NO ₃ ) ₃ , Gd(NO ₃ ) ₃ , Sm(NO ₃ ) ₃ , Tb(NO ₃ ) _{3 ,} etc. may be used. ), acetate (for example, La(CH ₃ CO ₂ ) ₃ , Ce(CH ₃ CO ₂ ) ₃ , Pr(CH ₃ CO ₂ ) ₃ , Nd(CH ₃ CO ₂ ) ₃ , Eu(CH ₃ CO ₂ ) ₃ , Gd(CH ₃ CO ₂ ) ₃ , Ho(CH ₃ CO ₂ ) ₃ , Yb(CH ₃ CO ₂ ) ₃ , Lu(CH ₃ CO ₂ ) _{3 ,} etc.), chloride (for example, LaCl ₃ , CeCl ₃ , PrCl ₃ , NdCl ₃ , SmCl ₃ , EuCl ₃ , GdCl ₃ , DyCl ₃ , TmCl _{3 ,} etc.).

The reducing agent is used to inhibit the reaction of tetravalent manganese (Mn ⁴⁺ ) with water to form manganese dioxide to blacken the surface of the particles, and to reduce the manganese (Mn ⁴⁺ ) of tetravalent to manganese (Mn ²⁺ ) of divalent. And add. The reducing agent can be appropriately selected within the range having the aforementioned reducing action and not affecting the parent of the fluoride phosphor. For example, hydrogen peroxide, oxalic acid, or the like can be used. In particular, hydrogen peroxide is preferred.

These are obtained by mixing a treatment liquid containing at least a rare earth element ion and a reducing agent with a fluoride phosphor core particle at a specific temperature and for a specific time to sufficiently contact the rare earth element ions with the surface of the particle, and then filtering The solvent such as ethanol or acetone or isopropyl alcohol is washed and dried to obtain the desired fluoride phosphor of the present invention. Further, it is not necessary to add a reducing agent from the beginning of the treatment liquid. In this case, after the rare earth element ions are contacted, a reducing agent is added to remove the coloration of the surface of the particles due to manganese dioxide. Another method is to contact the rare earth element ions, temporarily filter, dry, and then The solution treatment of the reducing agent removes the coloration of the surface of the particles due to manganese dioxide.

(semiconductor light emitting device)

Next, a configuration of a semiconductor light-emitting device including at least the above-described fluoride phosphor will be described as an example of an embodiment of the present invention. The semiconductor light-emitting device of the present invention is not limited to the following description.

Figure 2 is a cross-sectional view showing a semiconductor light emitting device according to an embodiment of the present invention.

The semiconductor light-emitting device is, for example, a semiconductor light-emitting element formed of a polyoxyxylene resin on a printed circuit board 16 having a rectangular parallelepiped shape made of a heat-resistant glass epoxy resin, and then an insulating substrate. 11. The P-type electrode 13a and the N-type electrode 14a provided on the upper surface of the semiconductor light-emitting device 11 are connected to the electrode portions 16a and 16b on the upper surface of the printed circuit board 16 by metal wires 15a and 15b, respectively. The electrode portions 16a and 16b are passed through a through hole having a circular arc shape in a cross-sectional shape in which the upper surface of the printed circuit board 16 and the lower surface are connected to each other, and are wound back to the lower surface of the printed circuit board 16 as a mounting surface, and extend to the bottom. Both ends of the mounting surface. Further, an insulating film may be used for the printed circuit board 16.

Then, a molding resin 32 such as a translucent polyoxynoxy resin as a sealing resin of the dispersion phosphor 21 is formed so as to form a trapezoidal cross section as shown in FIG. 2 so as to cover the entire semiconductor light-emitting device 11 A surface mount type semiconductor light-emitting device is formed on the printed circuit board 16.

The phosphor 21 is at least including the red of an embodiment of the present invention. a color-emitting fluoride phosphor, and further comprising other green-emitting phosphors that absorb blue-based light or ultraviolet light to emit light in a green region, such as a β-SiAlON-based phosphor, or A mixture of various orthosilicate-based phosphors, garnet-based phosphors having green light emission, and the like. The selection of the green light-emitting phosphor can be appropriately selected depending on the light-emitting color of the target semiconductor light-emitting device.

The semiconductor light-emitting device of the present invention is not limited to the above-described structure, and a phosphor 21 containing at least a fluoride phosphor according to an embodiment of the present invention can be used as long as light from the near-ultraviolet light to the blue region emitted from the semiconductor light-emitting device 11 can be used. The wavelength conversion is performed, and a semiconductor light-emitting device that emits light such as a white region by mixing light emitted from the semiconductor light-emitting device 11 with light emitted from the phosphor 21 can be used.

Next, as an embodiment of the above embodiment The fluoride phosphor of the present invention and its characteristics will be described.

[Example 1] (Production of Fluoride Fluorescent Core Particles)

A fluoride phosphor core particle represented by K ₂ Si _0.9 F ₆ :Mn _0.1 is produced as an example of a fluoride phosphor core particle represented by the formula of A ₂ MF ₆ : Mn.

Weighing 12.36 g (0.05 mol in terms of Mn) of K ₂ MnF ₆ and adding it to 900 ml of a 55 mass % HF aqueous solution and dissolving, then adding 99.12 g (0.45 m in terms of Si) of K ₂ SiF ₆ It was dissolved well by stirring, and this was made into the 1st solution.

Further, 39.1 g (0.5 mol of K) of KHF ₂ was weighed and added to 100 ml of another 5% by mass aqueous HF solution, and the mixture was sufficiently dissolved by stirring to obtain a second solution.

While stirring the first solution at room temperature, the second solution was added thereto in small portions and mixed. The precipitate produced by filtration separation was recovered by washing with isopropyl alcohol several times, and dried at 100 ° C for 2 hours to obtain a target fluoride phosphor core particle represented by K ₂ Si _0.9 F ₆ : Mn _0.1 .

(surface treatment of fluoride phosphor core particles)

Each treatment liquid was prepared under the feeding conditions of the composition shown in Table 1. For example, Example 1-1 in Table 1 is prepared by adding 0.26 g of cerium nitrate 6 hydrate (La(NO ₃ ) ₃ .6H ₂ O) (0.006 mol in terms of La) to 100 ml of pure water, and then A treatment liquid was prepared by adding 3.4 g of a 30% aqueous solution of H ₂ O ₂ as a reducing agent and stirring. Next, 10 g of the above-obtained fluoride phosphor core particles were added, and the mixture was stirred at room temperature for 1 hour. Subsequently, the surface-treated phosphor was separated by filtration, washed with isopropyl alcohol several times, and dried at 100 ° C for 1 hour to obtain a fluoride phosphor of the present invention having fluorinated ruthenium on the surface. The obtained fluoride phosphor was designated as Example 1-1. Similarly, the fluoride phosphor core particles obtained above were subjected to surface treatment using the treatment liquids of the feeding conditions of Examples 1-2 to 1-21 to obtain Examples 1-2 to 1-21, respectively. Fluoride phosphor.

For comparison, untreated fluoride phosphor core particles were compared In Example 1, a fluoride phosphor obtained by the same surface treatment as that of the treatment liquid of Example 1 of Patent Document 3 was used as Comparative Example 2.

Next, the luminance characteristics of the respective fluoride phosphor samples were examined. It is excited by LED blue light having an emission peak wavelength of 460 nm, and its luminance is measured by a luminance meter (Model: LS-110 KONICA MINOLTA) The illuminance chromaticity x, y was measured by a color luminance meter (model: CS-100A, manufactured by KONICA MINOLTA). At this time, a sharp cut filter (Model: Y-50, manufactured by HOYA CANDEO OPTRONICS Co., Ltd.) which filters out wavelengths of 500 nm or less is provided in the front portion of each luminance meter to remove the influence of blue light of the excitation light. Comparative Example 1 was set to 100 to show the obtained light-emitting luminance with respect to the lightness, and is shown in Table 2 together with the light-emitting color.

Next, the water resistance test of each fluoride phosphor sample was performed. 2 g of the fluoride phosphor was poured into 10 ml of pure water, and after allowing to stand for 1 hour, it was separated by filtration, washed with isopropyl alcohol, and dried at 100 ° C for 1 hour. The luminescent brightness of each sample after the water resistance test is shown in Table 2 together with the luminescent chromaticity and the brightness maintenance rate before and after the water resistance test.

From the results shown in Table 2, it was found that the brightness maintenance ratios after the water resistance tests of Examples 1-1 to 1-21 were the same as or higher than those of Comparative Examples 1 and 2. In particular, when a rare earth element of ruthenium, osmium, iridium, osmium, iridium, osmium or iridium is used, a preferable brightness maintenance ratio is exhibited.

Next, with respect to Example 1-3, Example 1-5, Example 1-7, and Untreated Comparative Example 1 in which the concentration of barium acetate in the treatment liquid was changed, an X-ray diffraction device (Model: XRD-6100 Shimadzu) was used. Prepared by the manufacturer, powder X-ray diffraction analysis was performed using a Cu tube. The resulting powder X-ray diffraction pattern is shown in Fig. 1. The triangular mark in Fig. 1 indicates the peak position of LaF ₃ of ICDD #00-032-0483. The untreated Comparative Example 1 did not have a peak of LaF ₃ and was found to be proportional to the concentration of cerium acetate. It can be understood from Fig. 1 that the substances present on the surface of the fluoride phosphor of Examples 1-3, 1-5 and Examples 1-7 are LaF ₃ .

Further, element mapping is also performed in EPMA for Embodiments 1-5. As a result, the surface of the sample confirmed the presence of a lanthanum element.

As described above, the fluoride phosphor of the present invention has a rare earth element fluorine compound on the surface of the phosphor particles, so that the red light-emitting fluoride phosphor having improved water resistance can be used.

[Industrial Applicability]

The fluoride phosphor of the present invention can be mainly used as a wavelength conversion material for a light source, but is particularly suitable for use in backlights for liquid crystal displays because of its high color purity, wide half-value of light-emitting peaks, and high durability. A phosphor for a light source. Further, since the semiconductor light-emitting device of the present invention has high color purity, and has a half-value width of a light-emitting peak, and is excellent in long-term stability, it can be applied to a light source for backlight use for liquid crystal displays.

Claims (5)

A fluoride phosphor characterized by having at least a rare earth element fluorine compound on a surface of a fluoride particle represented by the general formula A ₂ MF ₆ : Mn, wherein the rare earth element fluorine compound is made of lanthanum (La) or lanthanum (Ce), 鐠 (Pr), 钕 (Nd), 钐 (Sm), 铕 (Eu), 釓 (Gd), 鋱 (Tb), 镝 (Dy), 鈥 (Ho), 銩 (Tm), 镱a fluorine compound of at least one rare earth element selected from (Yb) and lanthanum (Lu), wherein M is at least one metal element selected from the group consisting of yttrium (Si), titanium (Ti), and yttrium (Ge), and A is At least one alkali metal element selected from sodium (Na) and potassium (K). The fluoride phosphor of claim 1, wherein the rare earth element fluorine compound is lanthanum fluoride (LaF ₃ ), cesium fluoride (CeF ₃ ), strontium fluoride (PrF ₃ ), cesium fluoride (NdF ₃ ) , samarium fluoride (SmF _3), europium fluoride (EuF _3), gadolinium fluoride (GdF _3), terbium fluoride (TbF _3), dysprosium fluoride (DyF _3), holmium fluoride (HoF _3), fluorine At least one selected from the group consisting of ruthenium (TmF ₃ ), yttrium fluoride (YbF ₃ ), and lanthanum fluoride (LuF ₃ ). A method for producing a fluoride phosphor comprising contacting a fluoride particle represented by the general formula A ₂ MF ₆ : Mn with a solution containing a rare earth element ion and a reducing agent to form a rare earth on the surface of the fluoride particle a step of classifying a fluorine compound, wherein M is at least one metal element selected from the group consisting of cerium (Si), titanium (Ti), and cerium (Ge), and A is at least selected from sodium (Na) and potassium (K). An alkali metal element). The method for producing a fluoride phosphor according to claim 3, wherein the rare earth element ion comprises lanthanum (La), cerium (Ce), praseodymium (Pr), cerium (Nd), cerium (Sm), cerium (Eu). Ions of at least one rare earth element selected from the group consisting of Gd, Tb, Dy, Ho, Tm, Yb, and Lu. A semiconductor light-emitting device characterized by comprising at least a semiconductor light-emitting element, a fluoride phosphor according to any one of claims 1 to 2, or a fluoride phosphor obtained by the production method of claim 3 or 4.