Phosphor manufacturing method

Abstract

To provide a phosphor that can achieve both of reduction in particle size and efficient light absorption and emission and a method for producing the same and a display device including the phosphor.SOLUTION: A phosphor contains Y or Lu, and Al, and Ce as elements. The phosphor has a particle size of 1 μm or less. The phosphor particle has a shape with a crystal face exposed. The phosphor particles are not flocculated.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a phosphor, a method for producing the same, and a display device using the phosphor. [Background technology]

[0002] Non-Patent Documents 1 to 3 disclose examples of conventional phosphors, nanoparticles, and methods for producing the same. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Author: CHLIN, BI-SHIOU CHIOU / JDLIN, Title: Engineering phosphors for improved brightness, Publisher: JOURNAL OF MATERIALS SCIENCE : MATERIALS IN ELECTRONICS 13 (2002) 705-711 [Non-Patent Document 2] Author: Yukiya Hakuta / Tsukasa Haganuma / Kiwamu Sue / Tadafumi Adschiri / Kunio Arai, Title: Continuous production of phosphor YAG:Tb nanoparticles by hydrothermal synthesis in supercritical water, Publication: Materials Research Bulletin 38 (2003) 1257-1265 [Non-Patent Document 3] Author: Gimyeong Seong / Seiichi Takami / Toshihiko Arita / Kimitaka Minami / Daisuke Hojo / Alain R. Yavari / Tadafumi Adschiri, Title: Supercritical hydrothermal synthesis of metallic cobalt nanoparticles and its dynamic thermo analysis, Publication: J. of Supercritical Fluids 60 (2011) 113-120 Summary of the Invention [Problem to be solved by the invention]

[0004] Phosphors are used, for example, in display devices. In display devices (particularly displays of mobile terminals, wearable terminals, etc.), high definition and miniaturization are progressing at the same time, and light-emitting devices that can achieve this are required. In order to achieve high definition and miniaturization in conventional light-emitting devices, for example, small particle size of phosphor particles and high efficiency of light absorption and emission are required, but achieving both small particle size of phosphor particles and high efficiency of light absorption and emission is a challenge.

[0005] As a display device, in recent years, displays made of micro LEDs (Light Emitting Diodes), in which pixels correspond to a light source one-to-one, have been attracting attention because they can achieve both high contrast and high definition, unlike conventional liquid crystal displays in which one light source corresponds to multiple pixels. In such displays made of micro LEDs, the light source is mainly a light emitting diode or a combination of a light emitting diode and a phosphor, and the size, i.e., the pixel size, is generally several tens of μm or less. On the other hand, most conventional phosphors have a particle size (particle diameter) of more than 10 μm, but as the pixel size becomes smaller with the increase in the resolution of displays, it is required to reduce the size of the phosphor to several μm or less, or even 1 μm or less, in order to obtain the desired color uniformly within the plane.

[0006] In addition, there is a light-emitting device that uses a laser light source. In such a light-emitting device using a laser light source, a light-emitting device that combines a laser light source and a phosphor is being considered to obtain white light. In a light-emitting device that combines a laser light source and a phosphor, a laser light emitted from a laser light source is irradiated onto a phosphor layer. Since a phosphor converts a part of the absorbed light into light and emits light, the difference in energy between the absorbed light and the emitted light becomes heat. In a light-emitting device that uses laser light, the phosphor layer is irradiated with light at a high laser light density, so local heat is generated in the phosphor layer. The material used for the phosphor is required to have heat resistance that can withstand that heat. In addition, the challenge for the phosphor layer is to suppress the heat generation and to improve the heat dissipation. In order to suppress the heat generation of the phosphor layer, it is necessary to shorten the heat dissipation path, that is, to make the phosphor layer thin and to achieve high-efficiency light absorption, and these are the challenges.

[0007] Thus, phosphors for use in micro-LEDs and lasers are required to have small particle size, high luminous efficiency, high light absorption efficiency, and high reliability (heat resistance).

[0008] By the way, phosphors include inorganic phosphors, organic phosphors, luminescent metal complexes (complex phosphors), quantum dots, etc., but it is difficult for any of the conventional materials to satisfy all of the properties required for the above-mentioned applications.

[0009] Conventional inorganic phosphors are synthesized by the solid-phase method, and although they are efficient, their size is 10 μm or more. Although it is possible to achieve the desired characteristics by reducing the particle size of conventional inorganic phosphors, the efficiency decreases for the following two reasons. (1) Crystallinity deteriorates and the probability of structural defects increasing. (2) The surface area per unit volume becomes larger, and the effect of structural defects near the surface becomes greater.

[0010] In other words, while conventional inorganic phosphors, especially those made of oxides and nitrides, are highly reliable, their efficiency decreases when they are reduced to nano-size, meaning that it is not possible to achieve both nano-size and high luminous efficiency.

[0011] In addition, organic fluorescent materials, luminescent complexes (complex fluorescent materials), and quantum dots have low heat resistance and environmental resistance, which greatly limits how they can be used.

[0012] Among inorganic phosphors, there are some in which the luminescent center element is responsible for luminescence, and the desired luminescence can be obtained when the luminescent center element is in a specific valence state. In order to achieve high luminous efficiency in such phosphors, it is important to control the valence of the luminescent center element. For example, Y3Al5O 12 :Ce (YAG:Ce) and Lu3Al5O 12In the YAG:Ce (LuAG:Ce) phosphor, Ce functions as the luminescence center, and Ce emits light when it is trivalent but not when it is tetravalent. In fact, in the solid-phase synthesis of YAG:Ce and LuAG:Ce phosphors in the past, the raw materials are mixed and fired in an air atmosphere to synthesize YAG:Ce and LuAG:Ce phosphors, and then fired in a reducing atmosphere to increase the luminescence efficiency. In other words, after firing in an air atmosphere, the valences of Ce are mixed between trivalent and tetravalent, while firing in a reducing atmosphere reduces Ce, increasing the proportion of trivalent Ce, thereby improving the luminescence efficiency. On the other hand, in terms of the particle size (particle diameter) of the phosphor, heat treatment of the phosphor particles at high temperatures, such as reduction firing, causes the particles to aggregate with each other, and the particle diameter of the secondary particles, which is the effective particle size, becomes larger.

[0013] As shown in Non-Patent Document 1, phosphors synthesized by the solid-phase method exhibit high brightness, but on the other hand, when the phosphor particles are mechanically crushed to reduce the size of the phosphor, the brightness is significantly reduced. For this reason, nano-sized particles by supercritical hydrothermal synthesis as reported in Non-Patent Document 2 and Non-Patent Document 3 are considered to be effective. Non-Patent Document 2 reports the synthesis of YAG:Tb phosphor by supercritical hydrothermal synthesis. Also, as mentioned above, the valence control of the luminescence center is important for controlling the luminescence characteristics of phosphors having a luminescence center. Non-Patent Document 3 reports the reduction of cobalt by formic acid, and the product changes from cobalt oxide to metallic cobalt by adding formic acid to the reaction raw material.

[0014] The present invention has been made to solve the above problems, and its object is to provide a phosphor that can achieve both small particle size and highly efficient light absorption and emission, a manufacturing method thereof, and a display device using the phosphor. Table 1 summarizes the characteristics of existing phosphors and the phosphor of the present invention.

[0015] [Table 1] [Means for solving the problem]

[0016] In order to solve the above problems, a phosphor according to one aspect of the present invention is a phosphor containing Y or Lu, Al, and Ce as elements, characterized in that the particle diameter (median diameter) of the phosphor is 1 μm or less (preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less).Furthermore, the phosphor particles are characterized in that the crystal planes are exposed, and the phosphor particles are not aggregated with each other.

[0017] In order to solve the above-mentioned problems, a manufacturing method (synthesis method) of a phosphor according to one embodiment of the present invention is characterized by including a step of mixing and reacting an aqueous metal salt solution containing a metal element constituting the phosphor with an aqueous alkali solution to convert the metal salt into a hydroxide, and a step of introducing the mixed and reacted reaction mixture into a main reactor maintaining a supercritical water state to synthesize particles of the phosphor.

[0018] A display device according to an aspect of the present invention uses the phosphor according to an aspect of the present invention.

[0019] (Key points for selecting the phosphor according to one embodiment of the present invention) [1] Phosphor particle size: The particle size (median diameter) of the phosphor particles is 1 μm or less (preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less). The particle size largely depends on the method of synthesizing the phosphor.

[0020] [2] Luminous efficiency: High luminous efficiency. In inorganic phosphors, where the luminescent center is responsible for emitting light, the important factors for high luminous efficiency are that the valence of the luminescent center element is appropriately controlled and that the crystallinity is high (few crystal defects), and these depend on the synthesis method of the phosphor. High crystallinity is also important for quantum dots.

[0021] [3] Optical density: The color can be changed with a phosphor layer only a few micrometers thick (because the phosphor layer needs to be thin).2+ , Ce 3+ ) or direct transition between bands exhibits high optical density. In the former case, controlling the valence of the luminescent center element is important to achieve high optical density. In addition, the smaller the particle size, the higher the density of the phosphor can be packed, which can increase the optical density in devices that actually use these phosphors.

[0022] [4] Reliability: They must be reliable over the long term (for example, they must be able to withstand use on light-emitting diodes without any protection). Inorganic phosphors are particularly excellent for long-term reliability, and inorganic phosphors based on oxide or nitride crystals are particularly good. Quantum dots are also inorganic crystals, but they contain highly reactive elements such as sulfur and selenium, which makes them unreliable over the long term, and they require technologies to suppress degradation, such as sealing.

[0023] The above [4] is the point at which the material was selected, regardless of the phosphor synthesis method. As the above [1], [2], and [3] depend on the phosphor synthesis method, supercritical hydrothermal synthesis was selected as the method that can realize them. In supercritical hydrothermal synthesis, for example, the reaction field can be supercritical water with a pressure of 25 MPa or more and a temperature of 370°C or more. This makes it possible to produce phosphor particles with a uniform element distribution and good crystallinity. Effect of the Invention

[0024] According to one embodiment of the present invention, it is possible to achieve both small particle size of phosphor and highly efficient light absorption and emission. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of an example of a flow-type supercritical hydrothermal synthesis reaction apparatus for synthesizing phosphor particles in supercritical water according to the present embodiment. [Diagram 2] 2 is a graph showing the results of XRD analysis of a YAG:Ce phosphor (YAG-1) according to the present embodiment, which was produced in a batch-type supercritical hydrothermal synthesis reaction apparatus in Example 1. [Diagram 3]4 is a SEM photograph showing a state in which particles of the YAG:Ce phosphor according to the present embodiment are not aggregated. [Figure 4] 1 is a SEM photograph showing a state in which particles of a conventional YAG:Ce phosphor are aggregated. [Diagram 5] This is an SEM photograph showing how fine YAG:Ce phosphor particles are bonded together by reducing and firing the phosphor. [Figure 6] 1 is a graph showing the results of XRD analysis of the YAG:Ce phosphor (YAG-2) synthesized in Example 2. [Figure 7] 1 is a graph showing the results of XPS analysis of the YAG:Ce phosphor (YAG-3) synthesized in Example 3. [Figure 8] 13 is a graph (YAG-4) showing the results of XRD analysis of a YAG:Ce phosphor according to the present embodiment, which was produced in a flow-type supercritical hydrothermal synthesis reactor with a main reactor temperature of 400° C. in Example 4. [Figure 9] 1 is a graph showing the results of XRD analysis of the LuAG:Ce phosphor (LuAG-1) synthesized in Example 5. [Figure 10A] 1 is a graph showing the results of XRD analysis of a LuAG:Ce phosphor (LuAG-2) synthesized in Example 6 using sulfate and acetate as raw materials. [Figure 10B] 1 is a graph showing the results of XRD analysis of a LuAG:Ce phosphor (LuAG-3) synthesized in Example 6 using lactate and acetate as raw materials. [Figure 11] 1 is a cross-sectional view showing a schematic configuration of a semiconductor module including a phosphor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] [About this embodiment] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A phosphor and a method for producing the same according to the present invention will now be described in detail with reference to the embodiments shown in the drawings.

[0027] In the method for producing a phosphor according to the embodiment of the present invention, a metal salt aqueous solution containing the metal elements constituting the phosphor is mixed and reacted with an alkaline aqueous solution to convert the metal salt into a metal hydroxide to produce a reaction mixture. The reaction mixture is then poured into a main reactor that maintains a supercritical water state to synthesize phosphor particles. In this way, by synthesizing in supercritical water, a phosphor with good crystallinity and small particle size can be synthesized. This makes it possible to obtain a phosphor that combines small particle size with highly efficient light absorption and emission.

[0028] FIG. 1 is a schematic diagram of an example of a flow-type supercritical hydrothermal synthesis reaction apparatus 100 for synthesizing phosphor particles according to the present embodiment in supercritical water.

[0029] The synthesis of phosphor particles in accordance with an embodiment of the present invention can be carried out using a batch-type (not shown) supercritical hydrothermal synthesis reaction apparatus or a flow-type supercritical hydrothermal synthesis reaction apparatus 100 as shown in FIG. 1.

[0030] In the method for producing a phosphor according to the present embodiment, a supercritical hydrothermal synthesis reaction apparatus is used to mix and react a metal salt aqueous solution and an alkaline aqueous solution, which are raw materials for the phosphor to be produced, at room temperature so that the metal salt becomes a hydroxide with a pH of 7 to 12. Thereafter, the mixed solution is held in a supercritical water state, and the mixed solution is reacted to synthesize phosphor particles, thereby producing the phosphor.

[0031] Hereinafter, each step of the method for synthesizing phosphor particles under supercritical water conditions in this embodiment will be described.

[0032] Raw material components that match the stoichiometric ratio of the phosphor to be produced are reacted with an alkaline aqueous solution such as an aqueous potassium hydroxide solution to bring the raw material components into alkaline conditions with a pH of 7 to 12. At this time, the raw material components are composed of a host and a luminescent center element to be doped into the host, and these can be water-soluble metal salts that are easily dissolved in water, such as metal nitrates, acetates, hydrochlorides, lactates, and sulfates, and preferably salts other than nitrates can be used.

[0033] As the matrix, for example, water-soluble metal salts of yttrium (Y), lutetium (Lu), gadolinium (Gd), lanthanum (La), scandium (Sc), aluminum (Al), gallium (Ga), or the like can be used.

[0034] As the luminescent center element, for example, water-soluble metal salts such as ytterbium (Yb), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), manganese (Mn), and chromium (Cr) can be used.

[0035] The valence of metal ions and hydroxide salts may change. For example, cerium (III) hydroxide is gradually oxidized in water to form cerium (IV) hydroxide. In particular, nitrate ions have an oxidizing ability, and oxidize cerium (III) hydroxide, promoting the formation of cerium (IV) hydroxide. For this reason, it is preferable to proceed with the synthesis reaction quickly after adjusting the raw material aqueous solution. In particular, when synthesizing phosphor particles using a batch-type supercritical hydrothermal synthesis reactor, it is preferable to synthesize phosphor particles in a supercritical state as soon as possible after generating the metal salt aqueous solution, preferably within 5 hours, more preferably within 2 hours.

[0036] [Batch-type supercritical hydrothermal synthesis reactor] The procedure for synthesizing phosphor particles using a batch-type supercritical hydrothermal synthesis reactor (not shown) will be described below.

[0037] After preparing the metal salt aqueous solution, an alkaline aqueous solution is gradually dropped into the metal salt aqueous solution to convert it into a hydroxide and adjust the pH to the desired level. An appropriate amount of the mixed solution is then filled into a pressure-resistant reactor and maintained at a temperature that results in a supercritical water state. Since supercritical water is at high temperature and high pressure, after filling the mixed solution, a tool such as a torque wrench is used to properly seal the reactor.

[0038] Here, the filling amount and holding temperature of the mixed solution are determined by the pressure resistance and heat resistance of the reactor. The state of supercritical water has a corresponding relationship between density, temperature, and pressure. Here, the density (filling amount) is determined by how much raw material is filled in a container with a fixed volume. In other words, when the density and temperature are determined, the pressure is uniquely determined. For example, when a reactor with a volume of 5 ml and a pressure resistance of 50 MPa is used, the liquid amount is 2 ml, and the temperature is 420°C, the pressure of the supercritical water is 40 MPa. Usually, the reaction temperature in supercritical water is at most about 600°C, and the reaction vessel is one that can withstand a heat-resistant temperature sufficiently higher than the reaction temperature in supercritical water, for example, one made of metal. When a component that generates gas by decomposition, such as formic acid, is included, it is necessary to consider the partial pressure of the generated gas.

[0039] The time for which the supercritical water is kept at a high temperature is appropriately set according to the rate of temperature rise of the reactor and the time required to complete the synthesis of the target particles. After keeping the temperature at a high temperature, the reactor is cooled by immersing it in water while it is sealed, and then the reactor is opened and the phosphor-containing solution is collected. If the solution contains a component that generates gas due to decomposition, such as formic acid, the reaction solution may scatter together with the gas when the reactor is opened, so care must be taken during the operation. In addition, the phosphor in the phosphor-containing solution is allowed to settle by a method such as standing or centrifugation, and the particles are separated and collected. After that, the phosphor particles with a particle size (median diameter) of 1 μm or less are obtained through washing and drying. Alternatively, a filter for repairing the particles can be installed in the supercritical hydrothermal synthesis reaction device, and phosphor particles with a particle size of 1 μm or less can be obtained through the filter.

[0040] [Flow-type supercritical hydrothermal synthesis reactor] The procedure for synthesizing phosphor particles using the flow-type supercritical hydrothermal synthesis reactor 100 shown in FIG. 1 will be described below.

[0041] [1st process] The metal salt aqueous solution of the raw material components is mixed with the alkaline aqueous solution in the first mixing section 61 of the supercritical hydrothermal synthesis reaction apparatus 100, and the metal salt aqueous solution of the raw material components is converted into a hydroxide salt solution.

[0042] The type of alkaline aqueous solution used here is not particularly limited, but a potassium hydroxide aqueous solution is preferred, followed by an alkali metal hydroxide aqueous solution other than potassium hydroxide, and the amount used is such that the final pH of the mixed solution is 7 to 12. A state of high supersaturation is created by converting metal salts such as nitrates to hydroxides. This makes it possible to produce phosphors with a size of 1 μm or less (nano-size) under supercritical water.

[0043] Meanwhile, the conversion of the metal salt to hydroxide is carried out at room temperature in the first mixing section 61 of the supercritical hydrothermal synthesis reaction apparatus 100. That is, as shown in FIG. 1, the second pump 12 and the third pump 13 (high pressure pumps) are used at the inlet of the supercritical hydrothermal synthesis reaction apparatus 100, the metal salt aqueous solution in the second container 2 is supplied through the first transfer pipe 111, and the alkaline aqueous solution in the third container 3 is supplied through the second transfer pipe 112, respectively, and the first transfer pipe 111 and the second transfer pipe 112 are structurally connected to each other at the end of the first transfer pipe 111, and the alkaline aqueous solution is transferred between the first transfer pipe 111 and the second transfer pipe 112 connected as described above, so that the metal salt aqueous solution and the alkaline aqueous solution are mixed and reacted in the first mixing section 61, and the metal salt is converted to hydroxide. At this time, the first transfer pipe 111 and the second transfer pipe 112 are structurally connected because the end of the first transfer pipe 111 has a through pipe shape in the form of a nozzle.

[0044] In addition, the mixing reaction time of the metal salt and the alkali is adjusted depending on the position of the second mixing section 62. This makes it possible to adjust the nucleation time. In this embodiment, the second mixing section 62 is positioned between the connection portion of the first transport pipe 111 and the second transport pipe 112 and the intersection portion of the second transport pipe 112 and the third transport pipe 113 for supplying preheated water, thereby maximizing the mixing time and minimizing the nucleation time.

[0045] [Second process] The solution converted to the hydroxide salt solution in the first step is mixed in the second mixing section 62 with preheated water that is supplied from the first container 1 by the first pump 11 via the third transfer pipe 113 and preheated to a high temperature. That is, the hydroxide salt solution is at room temperature, but is directly mixed in the second mixing section 62 with preheated water that is preheated to a predetermined first temperature (for example, about 400°C to 600°C) using the first preheater 41 equipped with a heater, and the second preheater 42 and the third preheater 43 equipped with a heater and a mantle heater. Therefore, the temperature of the reaction mixture becomes a predetermined second temperature (for example, about 360°C to 500°C).

[0046] This is because if a hydroxide salt solution at room temperature is directly supplied into the reaction section (main reactor 51) adjusted to supercritical water conditions, a very large temperature gradient difference will be generated between the upper and lower parts of the main reactor 51, causing the particle size distribution of the phosphor particles produced in the main reactor 51 to be non-uniform. Therefore, a uniform temperature is maintained within the main reactor 51 to ensure that the particle sizes of the phosphor particles have a uniform particle size distribution.

[0047] Also, the second mixer 62 and the main reactor 51 are connected by a nozzle installed through the main reactor 51. That is, the temperature of the reaction mixture directly mixed in the second mixer 62 with the preheated water preheated at 400-600°C using the first preheater 41 to the third preheater 43 is not a supercritical temperature, and the temperature of the upper part of the main reactor 51 is also close to the critical point of supercritical water due to heat loss. Therefore, the reaction mixture is sprayed from a deeper part than the inlet of the main reactor 51 through the nozzle located inside the main reactor 51, so that the crystallization synthesis reaction of phosphor particles is immediately carried out under the supercritical water condition of the main reactor 51. As a result, phosphor particles having a uniform size can be synthesized.

[0048] The main reactor 51, in which the synthesis is performed by the synthesis reaction of phosphor particles, is open at both ends (specifically, it is a tube-shaped vessel made of metal). The main reactor 51 is equipped with a main heater 44 (reaction section heater) on both sides of which the temperature is adjusted by a temperature adjustment device (not shown). The temperature adjustment device makes the main reactor 51 maintain the supercritical water condition by the main heater 44. In addition, a first temperature sensor 21 (thermocouple thermometer) is provided inside the main reactor 51. A second temperature sensor 22 (thermocouple thermometer) is provided downstream of the main reactor 51. The first temperature sensor 21 and the second temperature sensor 22 serve as sensors that detect whether the main reactor 51 maintains the supercritical water condition, and in particular, whether the outlet of the nozzle in the main reactor 51 that supplies the reaction mixture maintains the supercritical water condition. The first temperature sensor 21 and the second temperature sensor 22 also serve as safety sensors that prevent inconveniences caused by extreme temperature changes in the main reactor 51. The role of the safety sensor is to detect temperature changes and notify a separately provided safety device such as an alarm device or a shutoff device, thereby preventing problems caused by extreme temperature changes in the main reactor 51.

[0049] Furthermore, in the event of an abnormal increase in pressure, such as blockage of the first transfer pipe 111, the second transfer pipe 112, the third transfer pipe 113, and the fourth transfer pipe 114 or the main reactor 51, the pressure is controlled by the release valves 91, 92, and 93 and the back pressure valve 71. This makes it possible to effectively prevent inconveniences associated with an abnormal increase in pressure.

[0050] The phosphor-containing solution containing phosphor particles synthesized in the main reactor 51 is brought to room temperature as it passes through the cooler 101 via the fourth transfer pipe 114, and the phosphor particles are condensed. Therefore, the condensed phosphor particles are filtered through the filter 81 on the fourth transfer pipe 114 to separate the phosphor particles having a particle size larger than 1 μm from the phosphor-containing solution containing phosphor particles having a particle size of 1 μm or less, and are collected in the fourth container 4. Here, the filter 81 allows only particles having a particle size of 1 μm or less to pass through. Then, only the phosphor particles having a particle size of 1 μm or less are collected from the separated phosphor-containing solution, and the collected phosphor particles are washed and dried to obtain the phosphor particles.

[0051] Alternatively, if the synthesized phosphor particles have good dispersibility, the phosphor particles do not aggregate and pass through the filter 81. In this case, the phosphor in the phosphor-containing solution is allowed to settle by a method such as standing or centrifugation, and the particles are separated and collected. After that, through washing and drying, phosphor particles with a particle size (median diameter) of 1 μm or less are obtained.

[0052] The pressure of the water supplied from the first container 1 to the second mixing section 62 is monitored by a first pressure gauge 31. The pressure of the metal salt aqueous solution supplied from the second container 2 to the first mixing section 61 is monitored by a second pressure gauge 32. Moreover, the pressure of the phosphor-containing solution recovered in the fourth container 4 is monitored by a third pressure gauge 33. By determining whether the pressures measured by the first pressure gauge 31, the second pressure gauge 32, and the third pressure gauge 33 deviate from a predetermined reference pressure, it is possible to recognize a clogged pipe in the system.

[0053] By synthesizing phosphor particles using the supercritical hydrothermal synthesis reactor 100 according to the above-described process, phosphor particles can be continuously synthesized in a short reaction time without an additional heat treatment process. This saves time and energy for synthesizing phosphor particles, and is economically efficient.

[0054] The phosphor according to this embodiment is a phosphor containing Y or Lu, Al, and Ce as elements. The particle size (median diameter) of the phosphor particles is 1 μm or less (preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less). The phosphor particles have a shape with exposed crystal faces, and the phosphor particles do not aggregate with each other. Here, "the phosphor particles have a shape with exposed crystal faces, and the phosphor particles do not aggregate with each other" means that there are no bonding surfaces between the phosphor particles.

[0055] According to the phosphor of this embodiment, it is possible to obtain a phosphor material with a small particle size of 1 μm or less (due to the Ce valence being controlled). It is possible to achieve both small particle size of the phosphor and high efficiency light absorption and emission. Moreover, fine phosphors are necessary for applications such as displays with fine pixels and laser lighting, but it was difficult to obtain a phosphor that emits light efficiently with a small particle size (especially 1 μmm or less) with conventional inorganic phosphors. On the other hand, in this embodiment, since the particle size of the phosphor is 1 μm or less, it is possible to accommodate fine processing of the display device. For example, it is possible to accommodate fine processing up to several μm for each pixel size of a display device such as a display device. Specifically, when the pixels of the display device to be realized are several μm square and RGB pixels are formed by painting each color phosphor on these pixels, the phosphor needs to be smaller than the pixel size, but by having the particle size of the phosphor be 1 μm or less, it is possible to accommodate pixels of several μm square. In addition, if the efficiency is the same, the smaller the particle size of the phosphor, the thinner the phosphor layer can be formed, so that the heat dissipation path for the phosphor to generate heat can be shortened. This makes it possible to apply it to high-density light-emitting devices (the heat dissipation path can be shortened).

[0056] Here, the "particle size" of a phosphor particle refers to the radius of a virtual sphere inscribed in the particle. For example, in the case of a cubic particle, the particle size can be the diagonal of the cube, and the particle size can be √3 times the length of the side of the face. In the case of a rugby ball-shaped particle, the particle size can be the length of the long side. The particle size can be measured by observing an SEM (Scanning Electronic Microscope) photograph, or by diffraction and scattering by phosphor particles under laser light irradiation. It can be determined from an SEM photograph whether the crystal planes of the phosphor particles are exposed and the phosphor particles are not agglomerated with each other. In this case, if the contrast of the edges of each particle is clear, it is determined that the crystal planes of the phosphor particles are exposed and the phosphor particles are not agglomerated with each other.

[0057] The method for synthesizing phosphor particles according to the present embodiment can also be applied to the manufacture of other phosphor particles. In particular, the method for synthesizing phosphor particles according to the present embodiment is useful when the particle diameter is desired to be 1 μm or less, when a phosphor with high efficiency of light emission is required, or when the valence control of the luminescent center element is important (formic acid reduction effect), for example, Ce 3+ ,EU 2+ This method is suitable for synthesizing phosphors that have this as the luminescent center.

[0058] Furthermore, taking into consideration the circumstances in which the phosphor particles will be used, it is possible to assume that the phosphor will be dispersed in an organic solvent or polymer and then applied. In this case, surface modification or the addition of a dispersant is generally effective. In addition, the size and shape of the phosphor particles can be controlled by appropriately adding a surface modifier.

[0059] For example, a surface modifier that adsorbs to the particle surface of the phosphor, such as a dicarboxylic acid such as adipic acid or glutaric acid, or an amino acid such as aspartic acid, can be added, thereby improving dispersibility.

[0060] Specifically, a surface modifier can be simultaneously present in the raw aqueous solution, or the raw aqueous solution and the alkaline aqueous solution can be mixed, and then the surface modifier can be further mixed and the mixture can be transferred to the main reactor 51. This allows the surface of the phosphor particles to be covered with the modifier, and the dispersibility of the phosphor particles can be improved. Furthermore, some surface modifiers are adsorbed to specific crystal faces of the phosphor crystals, and depending on the selection of the surface modifier, it is also possible to control the crystal growth. In other words, when the crystal growth is controlled by surface modification, the growth rate of the crystals is changed. This allows the particle size to be controlled, or the particle growth will proceed on a specific crystal face, and therefore the particle shape of the phosphor can also be controlled.

[0061] The dispersibility of phosphor particles can also be improved by adding a dispersant to the phosphor particles. The dispersant can be, for example, a polymer having a functional group that interacts with the phosphor particle surface, such as sodium laurate, polyethylene glycol, or 12-hydroxystearic acid. It is preferable to select a dispersant that has affinity with the phosphor particle surface and at the same time affinity with the resin or solvent in which the phosphor is mixed.

[0062] As shown in Table 1, the phosphor having a particle size of 1 μm or less according to this embodiment is excellent in all of luminous efficiency, optical density, and reliability.

[0063] In the phosphor according to the present embodiment, the Ce concentration can be, for example, 1 mol % to 30 mol % (preferably 2 mol % to 5 mol %) relative to the number of moles of Y or Lu. By increasing the Ce concentration compared to conventional phosphors, the optical density of the phosphor can be improved.

[0064] In the phosphor according to the present embodiment, the valence of 50% to 100% of the Ce contained in the phosphor can be, for example, 3. This allows the luminous efficiency to be maintained even in particles with a high Ce concentration due to the uniform distribution of trivalent Ce within the phosphor particles.

[0065] The phosphor according to the present invention has a particle size of 1 μm or less and a composition formula of (A 1-X B X )3CO 12 (A is one or more of Lu / Y / Gd / Sc, B is one or more of Ce / Eu / Tb, C is one or more of Al / Ga, X is in the range of 0.01 to 0.2, and when B is Ce, 50% or more of the Ce contained therein has a valence of trivalent).

[0066] In the method for producing a phosphor according to the present embodiment, the metal salt aqueous solution may not contain ions or chemical species (such as nitrate ions) that have an oxidizing power for Ce ions. By not including nitrate ions that have an oxidizing power for Ce in the raw material aqueous solution, Ce can be easily obtained.3+ The abundance ratio of can be increased.

[0067] In the method for producing the phosphor according to the present embodiment, the metal salt aqueous solution may be one or more selected from acetate, lactate, and sulfate, which can increase the proportion of trivalent Ce in the phosphor as the valence of Ce.

[0068] In the method for producing a phosphor according to the present embodiment, an example is a mode in which a metal salt aqueous solution and an alkaline aqueous solution are supplied to supercritical water having a temperature of 370° C. or more and a pressure of 25 MPa or more. This makes it possible to increase the luminescence intensity by increasing the molar ratio of Al in the raw material to Y, Lu, and Ce higher than the stoichiometric ratio.

[0069] For example, in the method for producing a phosphor according to the embodiment of the present invention, a phosphor containing Ce as the luminescent center can be synthesized by supplying a raw material aqueous solution that does not contain nitrate ions and contains formic acid and an alkaline aqueous solution to supercritical water at 370°C or higher and 25 MPa or higher. This makes it possible to produce a phosphor with a small particle size and high luminescence efficiency that was not possible with the conventional method.

[0070] In the method for producing a phosphor according to the present embodiment, formic acid is added to the metal salt aqueous solution in an amount 10 times or more (preferably 100 times or more) the number of moles of Ce. In this way, by including formic acid having a reducing ability in the raw material aqueous solution (by decomposing formic acid in supercritical water to generate hydrogen), Ce can be reduced. 3+ The abundance ratio of can be increased.

[0071] The phosphor according to the present embodiment can be used in the display device according to the present embodiment. This makes it possible to obtain a display device that achieves both small particle size and highly efficient light absorption and emission. [Example 1] In Example 1, in a batch-type supercritical hydrothermal synthesis reaction apparatus, the main reactor was kept with supercritical water, and a mixed solution of a raw material aqueous solution containing nitrates of Y, Al, and Ce and a KOH aqueous solution was supplied to synthesize a YAG:Ce phosphor. When preparing the raw material aqueous solution, the ratio of each metal element was set to Y:Ce:Al=2.94:0.06:6.00. In addition, the synthesis was performed with the pH of the mixed solution set to 11.0, and the effect of the pH of the mixed solution on the synthesis of particles of the YAG:Ce phosphor was confirmed.

[0072] FIG. 2 is a graph showing the results of XRD (X-Ray Diffraction) analysis of the YAG:Ce phosphor (YAG-1) according to this embodiment, which was produced in the batch-type supercritical hydrothermal synthesis reactor in Example 1.

[0073] The XRD analysis shown in Figure 2 was carried out using an X-ray powder diffraction measuring device (name: Smart Lab 3K1d / 2dDSC) manufactured by Rigaku Corporation under the following conditions. The symbol α in the figure indicates a peak derived from YAG.

[0074] Tube voltage: 40kV Tube current: 30mA X-ray wavelength: Cu-Kα ray (1.5406Å) Optical system: Parallel beam method Slit configuration: Soller slit 0.5°, entrance slit 2mm, Receiving slit 8mm Detector: Scintillation counter Measurement range: 2θ=10deg-90deg Step width, scan speed: 0.02deg, 5deg / min The XRD analysis results confirmed the synthesis of YAG:Ce phosphor, as shown in FIG.

[0075] FIG. 3 is an SEM photograph of the particles of the YAG:Ce phosphor synthesized in Example 1. In the SEM photograph shown in FIG. 4, the particles of the YAG:Ce phosphor according to the present embodiment synthesized in a batch-type supercritical hydrothermal synthesis reaction apparatus were observed using a scanning electron microscope (SU-70 manufactured by Hitachi High-Technologies Corporation, high vacuum mode, acceleration voltage: 5 kV, measurement magnification: 30,000 times). In the YAG:Ce phosphor according to the present embodiment shown in FIG. 3, the contrast of the edges of each particle is clear, and it can be seen that there is no aggregation. The spherical and cubic particles in FIG. 3 are particles of the YAG:Ce phosphor, and the particle size is 0.2 μm at the minimum and 0.5 μm at the maximum.

[0076] Figure 4 shows an SEM photograph of a YAG:Ce phosphor obtained by synthesizing YAG:Ce using the coprecipitation method, which is one of the liquid phase methods, and then firing it to obtain light emission. The SEM photograph shown in Figure 5 shows the state of nano-sized YAG:Ce phosphor particles that were treated at 1300°C in a 2% hydrogen-98% argon atmosphere for three hours. As shown in Figure 5, it can be seen that the particles are adhered to each other (necking) by performing reduction firing to obtain highly efficient light emission in the YAG:Ce phosphor synthesized using the conventional solid phase method.

[0077] From this Example 1, it was found that a YAG:Ce phosphor can be synthesized by batch-type supercritical hydrothermal synthesis. It was also confirmed that a YAG:Ce phosphor can be synthesized by supercritical hydrothermal synthesis, in which the particle size of the phosphor is 1 μm or less, the phosphor particles have a shape in which the crystal planes are exposed, and the phosphor particles are not aggregated with each other.

[0078] [Example 2] In Example 2, in a batch-type supercritical hydrothermal synthesis reaction apparatus, a raw material aqueous solution containing Y, Al, and Ce with a pH of 10.9 and KOH was filled in the reactor, and the solution was heated with a heater maintained at 420°C to synthesize particles of YAG:Ce phosphor (YAG-2). The raw material aqueous solution used for synthesis was prepared using Al sulfate and Y and Ce acetates as raw materials, and the influence of the raw material salts was confirmed. Figure 6 shows the results of XRD analysis. It can be seen that YAG:Ce phosphor was synthesized even when the raw materials were sulfate and acetate. In addition, under excitation with black light that is effective in the wavelength range of 365 to 405 nm, the YAG:Ce phosphor particles obtained in this example showed stronger luminescence than the YAG:Ce phosphor particles obtained using nitrate as a raw material. This difference is due to the presence of nitrate ions NO 3- This is because Ce has an oxidizing power, and so in the aqueous solution it oxidizes trivalent Ce to tetravalent Ce. In other words, by synthesizing the YAG:Ce phosphor from a raw material aqueous solution that does not contain ionic species and molecular species (chemical species) with high oxidizing power, such as nitrate ions, it is possible to increase the ratio of trivalent Ce that contributes to the emission of the YAG:Ce phosphor.

[0079] This Example 2 shows that the luminescence intensity in YAG:Ce can be increased by appropriately selecting the raw material salts, specifically, by synthesizing YAG:Ce particles using sulfate and acetate as raw materials instead of nitrate.

[0080] [Example 3] In Example 3, in a batch-type supercritical hydrothermal synthesis reaction apparatus, a raw material aqueous solution containing formic acid and KOH and containing nitrates of Y, Al, and Ce with a pH of 10.9 was filled into the reactor, and particles of YAG:Ce phosphor (YAG-3) were synthesized by heating with a heater maintained at 420°C.

[0081] FIG. 7 is a graph showing the results of XPS (X-ray Photoelectron Spectroscopy) analysis of the YAG:Ce phosphor synthesized in Example 3. 4+At binding energies of 900 eV to 910 eV and 875 eV to 885 eV, 3+ This is the origin.

[0082] Table 2 shows 3+ and Ce 4+ The abundance ratio of

[0083] [Table 2]

[0084] The sum of the areas is the Ce listed in Table 2. 3+ and Ce 4+ In the YAG:Ce phosphor obtained in this example, 3+ accounts for 67% of the total Ce, and Ce 3+ The abundance ratio of Ce is 50% or more, and Ce does not contribute to the emission of YAG:Ce phosphor. 4+ Ce contributes more to luminescence than 3+ It can be seen that the ratio is high.

[0085] From this Example 3, it was found that by adding formic acid in the supercritical hydrothermal synthesis of the YAG:Ce phosphor, the proportion of trivalent Ce in the YAG:Ce phosphor becomes 50% or more. [Example 4] In Example 4, a YAG:Ce phosphor was synthesized by maintaining the main reactor 51 with supercritical water and supplying a mixed solution of a raw material aqueous solution containing nitrates of Y, Al, and Ce and a KOH aqueous solution in a flow-through supercritical hydrothermal synthesis reaction apparatus 100. The main reactor 51 was maintained at 400° C., and the synthesis was performed to confirm the effect of the temperature of the main reactor 51 on the synthesis of particles of the YAG:Ce phosphor.

[0086] FIG. 8 is a graph showing the results of XRD analysis of the YAG:Ce phosphor (YAG-4) according to this embodiment, which was produced in the flow-type supercritical hydrothermal synthesis reaction apparatus 100 in Example 4.

[0087] The XRD analysis shown in Figure 8 was carried out using an X-ray powder diffraction measuring device (name: Smart Lab 3K1d / 2dDSC) manufactured by Rigaku Corporation under the following conditions: The symbol α in the figure indicates a peak derived from YAG.

[0088] Tube voltage: 40kV Tube current: 30mA X-ray wavelength: Cu-Kα ray (1.5406Å) Optical system: Parallel beam method Slit configuration: Soller slit 0.5°, entrance slit 2mm, Receiving slit 8mm Detector: Scintillation counter Measurement range: 2θ=10deg-90deg Step width, scan speed: 0.02deg, 5deg / min From FIG. 8, it can be seen that the YAG:Ce phosphor was also synthesized in the flow-through type device.

[0089] From this Example 4, it was found that a YAG:Ce phosphor can be synthesized by flow-type supercritical hydrothermal synthesis.

[0090] [Example 5] In Example 5, in a batch-type supercritical hydrothermal synthesis reaction apparatus, a raw material aqueous solution containing nitrates of Lu, Al and Ce, which contained formic acid and KOH and had a pH of 11.0, was filled into the reactor, and heated with a heater maintained at 420°C to synthesize particles of LuAG:Ce phosphor (LuAG-1).

[0091] FIG. 9 is a graph showing the results of XRD analysis of the particles of the LuAG:Ce phosphor synthesized in Example 5. The symbol α in the figure indicates a peak derived from LuAG, and it can be seen that the LuAG:Ce phosphor was synthesized in Example 5. The luminescence of the obtained LuAG:Ce phosphor was also confirmed. From the above, it was confirmed that the LuAG:Ce phosphor can be synthesized by supercritical hydrothermal synthesis.

[0092] [Example 6] In Example 6, in a flow-type supercritical hydrothermal synthesis reaction apparatus, the main reactor was maintained with supercritical water, and a raw material aqueous solution containing Al sulfate and Lu and Ce acetates, and a mixed solution of a raw material aqueous solution containing Al lactate and Lu and Ce acetates, and an aqueous KOH solution were supplied to synthesize a LuAG:Ce phosphor.

[0093] Figure 10A shows the XRD analysis results of the LuAG:Ce phosphor (LuAG-2) synthesized from a raw aqueous solution containing sulfate and acetate in Example 6, and Figure 10B shows the XRD analysis results of the LuAG:Ce phosphor (LuAG-3) synthesized from a raw aqueous solution containing lactate and acetate in Example 6. The symbol α in the figure indicates a peak derived from LuAG, and the symbol β in the figure indicates a peak derived from CeO2. It can be seen that the LuAG:Ce phosphor was synthesized.

[0094] Lug emission from the LuAG:Ce phosphor obtained by synthesis was confirmed for all aqueous raw materials used. In addition, it was found that the by-product CeO2 was reduced by using lactate and acetate as raw materials. From the above, it was confirmed that LuAG:Ce phosphor can be synthesized using a flow-type supercritical hydrothermal synthesis apparatus, and that by-products can be suppressed by appropriately selecting raw materials.

[0095] [Display device] The phosphor according to this embodiment can be applied to a display device 300 shown in Fig. 11. The display device 300 includes a semiconductor module 200 including the phosphor according to the present embodiment.

[0096] (Configuration of semiconductor module) FIG. 11 is a cross-sectional view showing a schematic configuration of a semiconductor module 200 including a phosphor according to the present embodiment.

[0097] 11, semiconductor module 200 includes base substrate 201, electrodes 202, light-emitting elements 203, light-shielding layer 204, metal terminals 205, insulating layer 206, dummy elements 207, pad electrodes 208, first color conversion layer 209, and second color conversion layer 210. In semiconductor module 200, a plurality of light-emitting elements 203 are actually provided on base substrate 201 with electrodes 202 interposed therebetween, but in FIG. 11, the description will be given assuming that three light-emitting elements 203 are provided on base substrate 201 with electrodes 202 interposed therebetween.

[0098] (Base substrate) The base substrate 201 may have wiring formed on at least its surface so that it can be connected to the light emitting element 203. A driving circuit for driving the light emitting element 203 is formed on the base substrate 201. The material of the base substrate 201 is preferably a crystalline substrate such as a single crystal or polycrystal of aluminum nitride entirely made of aluminum nitride, or a sintered substrate. The material of the base substrate 201 is preferably a ceramic substrate such as alumina, glass, or a semimetallic or metallic substrate such as Si, or a laminate or composite substrate having an aluminum nitride thin film layer formed on the surface thereof. Metallic substrates and ceramic substrates have high heat dissipation properties, and are therefore preferable materials for the base substrate 201.

[0099] For example, by using a driving circuit that controls the light emission of light-emitting elements 203 formed on Si using integrated circuit formation technology as a base substrate 201, it is possible to manufacture a high-resolution display device with a high density of fine light-emitting elements 203.

[0100] (electrode) The electrode 202 is also called a bump, and electrically connects a metal wiring (not shown) and a metal terminal (not shown) provided on the light emitting element 203. The electrode 202 has a stepped portion in the light emission direction.

[0101] (Light emitting element) The light emitting element 203 may be a known one, specifically a semiconductor light emitting element. For example, there are GaAs, ZnO, or GaN based ones. The light emitting element 203 may be an LED (Light Emitting Diode) that emits red, yellow, green, blue, or purple light, or an LED that emits ultraviolet light. Among them, it is preferable to use a GaN based semiconductor that can emit blue to purple or purple to ultraviolet light as the light emitting element 203. Here, the light emitting element 203 emits blue light. The light emitting element 203 emits light from the upper surface in FIG. 11. The upper surface of the light emitting element 203 is a light emitting surface. The light emitting element 203 is electrically connected to a driving circuit formed on the base substrate 201 via the electrode 202. By disposing a first color conversion layer 209 and a second color conversion layer 210 that show a different emission color from the emission color of the light emitting element 203 when irradiated with light on the upper portion of the light emitting element 203, various emission colors in the visible light region can be shown. Therefore, it is possible to emit light with a short wavelength that can efficiently excite the color conversion material. In addition, the GaN-based semiconductor is preferable as the light emitting element 203 because it has characteristics such as high luminous efficiency, long life, and high reliability.

[0102] As the semiconductor layer of the light emitting element 203, a nitride semiconductor is preferably used in the semiconductor module 200 in which the nitride semiconductor is in the short wavelength region of the visible light region, the near ultraviolet region, or a region shorter than that, and is combined with a wavelength conversion material (phosphor). In addition, the nitride semiconductor is not limited to this, and may be a ZnSe-based, InGaAs-based, AlInGaP-based, or other semiconductor.

[0103] The light emitting device structure using semiconductor layers is preferably a structure having an active layer between a first conductive type (n-type) layer and a second conductive type (p-type) layer in terms of output efficiency, but is not limited to this. In addition, insulating, semi-insulating, and reverse conductive type structures may be partially provided in each conductive type layer, or these may be additionally provided to the first and second conductive type layers. Another circuit structure, for example a protective element structure, may also be additionally provided.

[0104] (light shielding layer) The light shielding layer 204 fixes the electrodes 202, the light emitting elements 203, the metal terminals 205, the insulating layer 206, the first color conversion layer 209, the second color conversion layer 210 and the transparent resin layer 211 to the base substrate 201, and prevents light from leaking from the side surfaces of the light emitting elements 203, the first color conversion layer 209, the second color conversion layer 210 and the transparent resin layer 211. The light shielding layer 204 is disposed between the adjacent light emitting elements 203 and between the adjacent first color conversion layer 209, the second color conversion layer 210 and the transparent resin layer 211, and separates the plurality of light emitting elements 203, the first color conversion layer 209, the second color conversion layer 210 and the transparent resin layer 211. The light shielding layer 204 covers the periphery of the first color conversion layer 209, the second color conversion layer 210 and the transparent resin layer 211 when viewed from above. The light-shielding layer 204 is also called an underfill, and can be formed, for example, by curing a liquid resin. The light-shielding layer 204 covers the upper surface of the base substrate 201, the side surfaces of the electrodes 202, the side surfaces of the light-emitting elements 203, the metal terminals 205, the insulating layer 206, the dummy elements 207, the first color conversion layer 209, the second color conversion layer 210, and the side surfaces of the transparent resin layer 211.

[0105] (Metal terminal, insulating layer, pad electrode) Metal terminal 205 is provided on base substrate 201 and serves to externally supply power for driving the drive circuit formed on base substrate 201. Metal terminal 205 is electrically connected to a power source (not shown) that supplies power for driving the drive circuit formed on base substrate 201. A representative material for metal terminal 205 is, for example, Au.

[0106] The metal terminal 205 penetrates the insulating layer 206 and contacts the pad electrode 208 formed on the upper surface of the base substrate 201. The insulating layer 206 is provided on the base substrate 201 and covers a part of the upper surface of the base substrate 201. The insulating layer 206 has an opening in the center of the upper surface. The metal terminal 205 covers and electrically connects to the pad electrode 208 exposed from the opening of the insulating layer 206. In other words, the metal terminal 205 penetrates the insulating layer 206 to electrically connect to the pad electrode 208. It is preferable that a part of the metal terminal 205 contacts the upper surface of the insulating layer 206.

[0107] (dummy element) The dummy element 207 is formed on the base substrate 201. The dummy element 207 is located outside the light emitting element 203 when viewed from above, and is mechanically connected onto the base substrate 201.

[0108] (Color conversion layer) First color conversion layer 209 and second color conversion layer 210 are made of the phosphor material according to this embodiment, a color conversion material such as a light absorbing material, a light scattering material such as titania, silica, alumina, and a base material such as a resin, and convert the wavelength of light emitted by light emitting element 203. First color conversion layer 209 is a green conversion layer that converts the light emitted by light emitting element 203 into green light, and second color conversion layer 210 is a red conversion layer that converts the light emitted by light emitting element 203 into red light.

[0109] The first color conversion layer 209 and the second color conversion layer 210 contact the upper part of each of the plurality of light emitting elements 203 adjacent to each other. In FIG. 11, the first color conversion layer 209 and the second color conversion layer 210 contact the upper part of each of the three light emitting elements 203. The first color conversion layer 209 is in direct contact with the light emitting element 203 arranged directly below it, and the second color conversion layer 210 is in direct contact with the light emitting element 203 arranged directly below it. In other words, there is nothing between the first color conversion layer 209 and the light emitting element 203 that blocks the light from the light emitting element 203 toward the first color conversion layer 209, and there is nothing between the second color conversion layer 210 and the light emitting element 203 that blocks the light from the light emitting element 203 toward the second color conversion layer 210. The upper part of one of the three light emitting elements 203 is exposed.

[0110] The height of the first color conversion layer 209 and the second color conversion layer 210 from the base substrate 201 is the same as the height of the light shielding layer 204 from the base substrate 201. The distance between the first color conversion layer 209 and the second color conversion layer 210 is preferably 0.1 μm or more and 20 μm or less when viewed from above. Since the distance between the first color conversion layer 209 and the second color conversion layer 210 is 0.1 μm or more and 20 μm or less when viewed from above, the thickness of the portion of the light shielding layer 204 between the first color conversion layer 209 and the second color conversion layer 210 is 0.1 μm or more and 20 μm or less. This thickness is the thickness along the direction in which the first color conversion layer 209 and the second color conversion layer 210 are arranged. In addition, the first color conversion layer 209 and the second color conversion layer 210 preferably have a phosphor with a median diameter of 2 μm or less. This allows the sizes of first color conversion layer 209 and second color conversion layer 210 to be reduced, and therefore the size of semiconductor module 200 to be reduced.

[0111] In addition, first color conversion layer 209 and second color conversion layer 210 can be formed by coating or photolithography on the flat surface of light emitting element 203. In this way, color conversion layers can be disposed on a plurality of light emitting elements 203.

[0112] (Transparent resin layer) 11, the semiconductor module 200 has a transparent resin layer 211 disposed on top of one light-emitting element 203 among the three light-emitting elements. The transparent resin layer 211 transmits light emitted from the light-emitting element 203 and emits the light from the upper surface. The transparent resin layer 211 transmits light emitted from the light-emitting element 203 disposed directly below it without converting the wavelength of the light.

[0113] That is, blue light is emitted from the transparent resin layer 211. The transparent resin layer 211 may contain a scattering material such as silica, if necessary.

[0114] The semiconductor module 200 can emit the three primary colors of red light, green light, and blue light by disposing the first color conversion layer 209, which is a green color conversion layer, the second color conversion layer 210, which is a red color conversion layer, and the transparent resin layer 211 on each of the three light emitting elements 203. In the portion where blue light is emitted to the outside, the transparent resin layer 211 is disposed on the upper part of the light emitting element 203, so that the light emitting element 203 can be protected. In addition, by disposing the same light diffusing elements on the upper parts of the three light emitting elements 203, it becomes easier to obtain optical characteristics. In other words, the semiconductor module 200 can be easily manufactured. Furthermore, a display device in which the semiconductor module is incorporated can perform color display by controlling each of the light emitting elements 203.

[0115] In the semiconductor module 200, the transparent resin layer 211 does not necessarily have to be disposed.

[0116] (Other embodiments) In this embodiment, the phosphor was manufactured as either YAG:Ce or LuAG:Ce, but any phosphor of any chemical structure may be used as long as the particle size of the phosphor containing the elements Y or Lu, Al, and Ce is 1 μm or less, the phosphor particles have a shape with exposed crystal faces, and the phosphor particles are not agglomerated with each other.

[0117] The present invention is not limited to the above-described embodiment, but can be embodied in various other forms, and is particularly suitable for phosphors having Ce and Eu as luminescence centers and made of an oxide as a host. Therefore, the embodiment is merely illustrative in every respect and should not be interpreted in a restrictive manner. The scope of the present invention is set forth in the claims, and is not restricted in any way by the text of the specification. Furthermore, all modifications and alterations within the scope of the claims are within the scope of the present invention. More specifically, a phosphor having a particle size of 1 μm or less and a composition formula of (A 1-X B X )3CO 12(A is one or more of Lu / Y / Gd / Sc, B is one or more of Ce / Eu / Tb, C is one or more of Al / Ga, X is in the range of 0.01 to 0.2, and when B is Ce, 50% or more of the Ce contained therein has a valence of trivalent). [Explanation of symbols]

[0118] 1 1st container 2 Second container 3 Third container 4 4th container 11 First Pump 12 Second pump 13 Third Pump 21 First temperature sensor 22 Second temperature sensor 31 No. 1 pressure gauge 32 Second pressure gauge 33 Third pressure gauge 41 First preheater 42 Second preheater 43 Third preheater 44 Main heater 51 Main Reactor 61 1st mixing section 62 2nd mixing section 71 Backpressure valve 81 Filters 91 Release valve 100 Supercritical hydrothermal synthesis reactor 101 Cooler 111 1st transfer pipe 112 2nd transfer pipe 113 3rd transfer pipe 114 4th transfer pipe 200 Semiconductor Modules 201 Base substrate 202 Electrode 203 Light emitting element 204 Light shielding layer 205 Metal terminal 206 Insulating Layer 207 Dummy element 208 Pad Electrode 209 1st color conversion layer 210 Second color conversion layer 211 Transparent resin layer 300 display device

Claims

1. A method for producing a phosphor containing Y or Lu, Al, and Ce as elements, comprising the steps of: a step of mixing and reacting an aqueous solution of a metal salt containing a metal element constituting the phosphor with an aqueous solution of an alkali to convert the metal salt into a hydroxide; A step of introducing the reaction mixture into a main reactor that is maintained in a supercritical water state to synthesize particles of the phosphor; Including, The metal salt aqueous solution contains at least one selected from an acetate, a lactate, and a sulfate, Formic acid is added to the metal salt aqueous solution so that the number of moles of formic acid is 10 times or more the number of moles of Ce in the aqueous solution, A method for producing a phosphor, comprising obtaining phosphor particles having a median diameter of 1 μm or less, a composition formula represented by the following formula (1), and an abundance ratio of Ce 3+ in the Ce contained therein of 50% or more: (A 1-X Ce X ) 3 Al 5 O 12 ... (1) (In formula (1), A is Y or Lu, and X is in the range of 0.01 to 0.2.)

2. A method for producing the phosphor according to claim 1, comprising the steps of: A method for producing a phosphor, comprising using a sulfate and an acetate, or a lactate and an acetate, in the aqueous metal salt solution.

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