TW202140747A - Phosphor particle, composite, light-emitting device and self-luminous display - Google Patents

Abstract

A phosphor particle for a micro LED or mini LED, formed from β-SiAlON. A cured sheet produced using this phosphor particle by the following sheet production procedure exhibits the optical characteristics described below. ＜Sheet production procedure＞ (1) 40 parts by mass of the phosphor particle and 60 parts by mass of a silicone resin OE-6630 manufactured by Dow Corning Toray Co., Ltd. are subjected to an agitation and defoaming treatment using a planetary centrifugal mixer to obtain a uniform mixture. (2) A sheet material is obtained by applying the mixture obtained in (1) dropwise to a transparent first fluororesin film and overlaying an additional transparent second fluororesin film on the dropped material. The resulting sheet material is then shaped into an uncured sheet using rollers having a gap that is 50 µm greater than the total thickness of the first fluororesin film and the second fluororesin film. (3) The uncured sheet obtained in (2) is heated at 150°C for 60 minutes. Then, the first fluororesin film and the second fluororesin film are detached to obtain a cured sheet with a film thickness of 50±5 µm. ＜Optical characteristics＞ If the intensity at the peak wavelength of blue light emitted from a blue LED with a peak wavelength in a range from 450 nm to 460 nm is deemed Ii [W/nm], and when blue light is irradiated onto one surface of the cured sheet, if the intensity of the light emitted from the other surface of the cured sheet is deemed It [W/nm] for the peak wavelength in the range from 450 nm to 460 nm and Ip [W/nm] for the peak wavelength in the range from 500 nm to 560 nm, then It/Ii is 0.41 or less and Ip/Ii is 0.03 or greater.

Description

Phosphor particles, composites, light-emitting devices, and self-luminous displays

The present invention relates to phosphor particles, composites, light-emitting devices, and self-luminous displays. More specifically, it relates to phosphor particles for Micro LED or Mini LED, a composite using the particles, a light-emitting device provided with the composite, and a self-luminous display provided with the light-emitting device.

As far as newer displays are concerned, Micro LED displays are known. In Non-Patent Document 1, Micro LED displays are classified as self-luminous displays using LEDs (Micro LEDs) with a chip size of less than 100 μm square. In the Micro LED, a phosphor that converts blue light into red and green light is placed on the blue LED to obtain the three colors of RGB. In Figure 11 of Non-Patent Document 2, the schematic structure of the Micro LED is introduced. The Micro LED display is a self-luminous type that does not use a liquid crystal shutter or polarizing plate. This is fundamentally different from the conventional "LED backlight LCD TV". The structure is simple, the light extraction efficiency is high in principle, and the viewing angle is very limited.

In addition, we also know that "Mini LED" is a technology that is regarded as similar to Micro LED. Mini LEDs and displays using Mini LEDs are the same as Micro LED and Micro LED displays except that the chip size is 100 μm or more (more specifically, 100 μm or more and 200 μm or less) (see also Non-Patent Document 3) Classification recorded in). In other words, displays using Mini LEDs are basically self-luminous. [Prior Technical Literature] [Non-Patent Literature]

[Non-Patent Document 1] A survey of the latest trends in 2019 next-generation display technology and related materials/processes (Fuji Chimera Research Institute, Inc) [Non-Patent Document 2] Appl. Sci. 2018, 8, 1557 [Non-Patent Document 3] The Journal of The Institute of Image Information and Television Engineers Vol. 73, No. 5, pp. 939～942 (2019)

[The problem to be solved by the invention]

As mentioned above, in Micro LED or Mini LED, a light conversion layer that converts blue light into red light and green light is placed on the blue LED to obtain the three colors of RGB. More specifically, there is also a case where a phosphor sheet containing a light conversion material such as a phosphor is provided on the blue LED.

Considering the use of the so-called "display", it is ideal for the phosphors used for Micro LED or Mini LED to have high luminous efficiency and to appropriately control indicators related to light "transmission", for example. However, according to the insights of the inventors of the present case, for example, as far as the conventional phosphors for lighting purposes are concerned, the design of the display is not considered at all, and it is not suitable for Micro LED or Mini LED.

The present invention was completed in view of this situation. One of the objectives of the present invention is to provide phosphor particles that can be ideally used in Micro LED displays and/or Mini LED displays. [Means to solve the problem]

The inventors of the present case have completed the invention provided below to solve the above-mentioned problems.

According to the present invention, Provide a kind of phosphor particles, which are phosphor particles for Micro LED or Mini LED made of β-type silicon aluminum oxynitride, The hardened sheet made by the following sheet production procedure satisfies the following optical characteristics.

＜Sheet production procedure＞ (1) Using a rotating and revolving mixer, 40 parts by mass of the phosphor particles and 60 parts by mass of Toray Dow Corning's polysiloxane resin OE-6630 are subjected to stirring treatment and defoaming treatment to obtain a uniform mixture. (2) Obtain a sheet in which the mixture obtained in (1) is dropped on a transparent first fluororesin film, and a transparent second fluororesin film is superposed on the drops. This sheet was formed into an uncured sheet using a roller having the total thickness of the first fluororesin film and the second fluororesin film plus a gap of 50 μm. (3) The uncured sheet obtained in (2) was heated at 150°C for 60 minutes. After that, the first fluororesin film and the second fluororesin film were peeled off to obtain a cured sheet having a film thickness of 50±5 μm. ＜Optical characteristics＞ Let the intensity of the blue light emitted by the blue LED with a peak wavelength in the range of 450nm to 460nm at the peak wavelength be Ii[W/nm], and when the blue light is irradiated on one side of the hardened sheet The intensity of the peak wavelength of the light emitted from the other side of the cured sheet in the range of 450nm to 460nm is It[W/nm] and the intensity of the peak wavelength in the range of 500nm to 560nm is Ip[W/nm ]Time; It/Ii is 0.41 or less, and Ip/Ii is 0.03 or more.

Also, according to the present invention, Provided is a composite including the phosphor particles described above, and a sealing material that seals the phosphor particles.

Also, according to the present invention, Provided is a light-emitting device including a light-emitting element that emits excitation light, and the composite body that converts the wavelength of the excitation light.

Also, according to the present invention, Provided is a self-luminous display including the above-mentioned light-emitting device. [Effects of the invention]

With the present invention, phosphor particles that can be ideally used in Micro LED displays and/or Mini LED displays are provided.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, the same components are denoted by the same symbols, and the description will be omitted as appropriate. In order to avoid complication, there may be (i) when there are multiple identical components in the same drawing, only one of them is marked with a symbol, and not all of them are marked with a symbol, (ii) especially after Figure 2, not Once again, the same constituent elements as in FIG. 1 are labeled with symbols. All the figures are for illustration purposes only. The shapes, size ratios, etc. of the various components in the diagram do not necessarily correspond to actual objects.

In this specification, the description of "X to Y" in the description of the numerical range means X or more and Y or less unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".

In this manual, "LED" stands for Light Emitting Diode (Light Emitting Diode). In this manual, the term "phosphor particles" sometimes refers to phosphor powder that is a group of phosphor particles, depending on the context.

＜Phosphor particles for Micro LED or Mini LED＞ The phosphor particles of this embodiment are used for Micro LED or Mini LED. That is, the phosphor particles of this embodiment are used for the purpose of converting the color of light emitted from Micro LED or Mini LED to other colors. The definitions of Micro LED and Mini LED are described in Non-Patent Document 1 and others. The phosphor particles of this embodiment are made of β-type silicon aluminum oxynitride. In this way, the phosphor particles of this embodiment usually convert blue light into green light. The hardened sheet made by using the phosphor particles of the present embodiment through the following sheet production procedure satisfies the following optical characteristics.

＜Sheet production procedure＞ (1) Using a rotating and revolving mixer, 40 parts by mass of the phosphor particles and 60 parts by mass of Toray Dow Corning's polysiloxane resin OE-6630 are subjected to stirring treatment and defoaming treatment to obtain a uniform mixture. (2) Obtain a sheet in which the mixture obtained in (1) is dropped on a transparent first fluororesin film, and a transparent second fluororesin film is superposed on the drops. This sheet was formed into an uncured sheet using a roller having the total thickness of the first fluororesin film and the second fluororesin film plus a gap of 50 μm. Here, the so-called "using rollers with gaps to form an uncured sheet" refers to passing the sheet through the gap between a set of rollers arranged opposite to each other. In addition, the first fluororesin film and the second fluororesin film are preferably the same film. At this time, the gap between the rollers is twice the thickness of one film plus 50 μm. (3) The uncured sheet obtained in (2) was heated at 150°C for 60 minutes. After that, the first fluororesin film and the second fluororesin film were peeled off to obtain a cured sheet with a film thickness of 50±5 μm.

＜Optical characteristics＞ Let the intensity of the blue light emitted by the blue LED with a peak wavelength in the range of 450nm to 460nm at the peak wavelength be Ii[W/nm], and when the blue light is irradiated on one side of the hardened sheet The intensity of the peak wavelength of the light emitted from the other side of the cured sheet in the range of 450nm to 460nm is It[W/nm] and the intensity of the peak wavelength in the range of 500nm to 560nm is Ip[W/nm ]Time; It/Ii is 0.41 or less, and Ip/Ii is 0.03 or more.

The inventors of the present case believe that when obtaining ideal phosphor particles for Micro LED or Mini LED, it is important to use the characteristics that are close to the actual "transmitted light" of the display to be evaluated as an index to design the phosphor. Light body particles. Based on this consideration, the inventors of the present case used the method described in the above "Sheet Making Procedure" to make a sheet containing phosphor particles composed of β-type silicon aluminum oxynitride and a specific resin, and then place the sheet on The indicators related to the transmitted light when on the blue LED are used as design indicators. Specifically, the index corresponding to the degree of absorption of the blue light of the sheet is set to It/Ii, and the index corresponding to the degree of conversion efficiency of the sheet to convert blue light to green light is set to Ip /Ii. In addition, the inventors of the present case have discovered that phosphor particles with an It/Ii of 0.41 or less and an Ip/Ii of 0.03 or more are ideally used in Micro LEDs or Mini LEDs. The use of such phosphor particles to form Micro LED or Mini LED is related to the high color gamut of the display.

By the way, if the polysiloxane resin OE-6630 manufactured by Toray Dow Corning Company cannot be obtained during sheet production, as a substitute, the polysiloxane material SCR-1011 for LEDs manufactured by Shin-Etsu Chemical Co., Ltd. can be used. SCR-1016 or KER-6100/CAT-PH (the amount used is the same as OE-6630). According to the findings of the inventors of this case, even if these materials manufactured by Shin-Etsu Chemical Co., Ltd. are used as a substitute for OE-6630, the value of It/Ii and Ip/Ii will hardly change.

When obtaining the phosphor particles of the present embodiment, in addition to selecting appropriate materials, it is also important to select appropriate manufacturing methods and manufacturing conditions. By appropriately selecting the manufacturing method and manufacturing conditions, the particle size, particle shape, etc. can be appropriately controlled, and phosphor particles with an It/Ii of 0.41 or less and Ip/Ii of 0.03 or more can be easily obtained. The details of the manufacturing conditions are described below. For example, by appropriately adjusting the conditions of the following low-temperature calcination step (annealing step), acid treatment step, crushing step, etc., It/Ii of 0.41 or less and Ip/Ii of 0.03 or more can be obtained. Phosphor particles.

It/Ii may be 0.41 or less, preferably 0.40 or less, more preferably 0.39 or less, more preferably 0.30 or less, and particularly preferably 0.20 or less. As for the lower limit of It/Ii, considering the actual design point of view, it is, for example, 0.01. Ip/Ii may be 0.03 or more, preferably 0.04 or more, and more preferably 0.05 or more. As for the upper limit of Ip/Ii, considering the actual design point of view, it is 0.5, for example.

Hereinafter, the description of the phosphor particles of this embodiment will be continued.

(General formula of β-type silicon aluminum oxynitride phosphor) The phosphor particles of this embodiment are composed of the general formula Si _12-a Al _a O _b N _16-b : Eu _x (where 0＜ a≦3; 0＜b≦3; 0＜x≦0.1) represents the structure of β-type silicon aluminum oxynitride phosphor.

(Particle size) When the volume-based cumulative 50% particle size and the volume-based cumulative 90% particle size of the phosphor particles of this embodiment measured by the laser diffraction scattering method are D ₅₀ and D ₉₀ , respectively, D ₅₀ It is preferably 5 μm or less, more preferably 0.2 μm or more and 5 μm or less, and more preferably 0.5 μm or more and 3 μm or less. D ₉₀ is preferably 10 μm or less, more preferably 8 μm or less, and more preferably 5 μm or less. D ₅₀ and D ₉₀ , 0.5g of phosphor particles are put into 100ml of ion-exchange aqueous solution mixed with 0.05% by mass of sodium hexametaphosphate, and homogenized by ultrasonic wave with oscillation frequency of 19.5±1kHz and amplitude of 31±5μm A homogenizer is a value measured on a liquid obtained by dispersing the tip in the center of the liquid for 3 minutes.

(Diffuse reflectance) With regard to the phosphor particles of the present embodiment, the diffuse reflectance of light with a wavelength of 800 nm is preferably 85% or more, and more preferably 90% or more. The lower limit of the diffuse reflectance of light with a wavelength of 800 nm is, for example, 80%.

The phosphor is irradiated with light (for example, light with a wavelength of 800 nm), which is the activating element of the β-type silicon aluminum oxynitride phosphor, to measure the diffuse reflectance, thereby confirming the crystal defects of the phosphor , Excess light absorption caused by compounds other than the β-type silicon aluminum oxynitride of the present invention (also called out-of-phase). For example, by intensive mechanical pulverization to obtain a phosphor with a small particle size, the crystal defects on the surface of the phosphor particles will be increased at the same time. Therefore, light with a wavelength of 800 nm becomes easy to be absorbed by the defect. As a result, the diffuse reflectance may be reduced to less than 95%.

For the phosphor particles of this embodiment, the light absorption rate for light with a wavelength of 600 nm is preferably 10% or less, more preferably 8% or less, and more preferably 5% or less. The lower limit of the light absorption rate of light with a wavelength of 600 nm is practically 0.5%. Like light with a wavelength of 800nm, Eu, which is an activating element of the phosphor, does not absorb light at a wavelength that would not otherwise be absorbed, but there is still light with a wavelength of 600nm. By evaluating the absorptivity of light with a wavelength of 600nm, it is possible to confirm the degree of absorption of excess light due to defects in the phosphor.

For the phosphor particles of this embodiment, the 455 nm light absorption rate is preferably 40% or more and 80% or less. By designing the 455nm light absorption rate within this value range, because the light from the blue LED will not pass through unnecessarily, it can be ideally used in Micro LED displays or Mini LED displays.

For the phosphor particles of this embodiment, the internal quantum efficiency is preferably 50% or more. By making the internal quantum efficiency above 50%, the light from the blue LED will be moderately absorbed, and sufficient green light will be emitted. The upper limit of the internal quantum efficiency is not specified, and is, for example, 90%.

For the phosphor particles of this embodiment, the external quantum efficiency is preferably 20% or more. By making the external quantum efficiency above 20%, the light from the blue LED will be moderately absorbed, and sufficient green light will be emitted. The upper limit of the external quantum efficiency is not specified, but is 72% or less, for example.

(Method of manufacturing phosphor particles) The manufacturing method of the phosphor particles of this embodiment is not particularly limited. It can be manufactured by selecting appropriate materials plus selecting appropriate manufacturing methods and manufacturing conditions.

The phosphor particles of this embodiment can be manufactured by the following steps, for example. ･The calcination step of calcining the raw material powder obtained after mixing the starting materials, ･The low-temperature calcination step (annealing step) performed after temporarily pulverizing the calcined product obtained in the calcination step, ･The acid treatment step in which the low-temperature calcined powder obtained after the low-temperature calcining step (annealing step) is treated with acid, ･Crush the powder after the acid treatment step to perform the pulverization step of micronization, and ･A decantation step to remove the fine powder generated in the pulverization step.

By the way, in this embodiment, the so-called "step" not only includes independent steps, even if it is indistinguishable from other steps, it is included in this term as long as it can achieve the desired purpose of the step.

According to the findings of the inventors of the present application, it is possible to easily produce phosphor particles having an It/Ii of 0.41 or less and an Ip/Ii of 0.03 or more by appropriately performing the pulverization step after the acid treatment step. This manufacturing method is different from the conventional manufacturing method of β-type silicon aluminum oxynitride phosphor. However, in the phosphor particles of this embodiment, various conditions can be adopted for other specific manufacturing conditions, provided that the originality of the above-mentioned manufacturing method is adopted.

Hereinafter, the above steps will be described respectively.

･Calcination step In the calcining step, the raw material powder obtained by mixing the starting materials is calcined. The raw material powders preferably include europium compounds, silicon nitride, and aluminum nitride. Silicon nitride and aluminum compounds are materials used to form the framework of β-type silicon aluminum oxynitride, and europium compounds are materials used to form luminescent centers. The raw material powder may further contain β-type silicon aluminum oxynitride. β-type silicon aluminum oxynitride is a material that will become aggregates or cores. The form of the above-mentioned components contained in the raw material powder is not particularly limited, and it is preferable that they are all in powder form.

The europium compound includes, for example, europium-containing oxides, europium-containing hydroxides, europium-containing nitrides, europium-containing oxynitrides, and europium-containing halides. These can be used individually or in combination of 2 or more types. Among them, it is preferable to use europium oxide, europium nitride, and europium fluoride separately, and it is more desirable to use europium oxide separately.

In the calcination step, europium can be classified into those that are solid-soluble in β-type silicon aluminum oxynitride, those that are volatile, and those that remain as heterogeneous components. The heterogeneous components containing europium can be removed by acid treatment or the like. However, when it is produced in a large amount, the acid treatment produces insoluble components and the brightness decreases. Moreover, as long as it is a different phase that does not absorb excess light, it may be in a residual state, and europium may be contained in this different phase. In addition, when the europium compound is added before the calcination in the multiple calcination steps, the raw material of the β-type silicon aluminum oxynitride phosphor other than the europium compound may be added together with the europium compound.

The total amount of europium used is not particularly limited, but it is preferably at least 3 times the amount of europium in solid solution in the β-type silicon aluminum oxynitride phosphor finally obtained, and more preferably at least 4 times. In addition, the total amount of europium contained in the raw material powder is not particularly limited, and it is preferably 18 times or less the amount of europium in solid solution in the β-type silicon aluminum oxynitride phosphor finally obtained. Thereby, the amount of insoluble heterogeneous components produced by the acid treatment can be reduced, and the brightness of the obtained β-type silicon aluminum oxynitride phosphor can be improved.

In the calcination step, for the raw material powder containing the europium compound, for example, a method of dry mixing, a method of wet mixing in a passive solvent that does not substantially react with the components of the raw material and then removing the solvent can be used. To get. As for the mixing device, for example, a V-type mixer, a rocking mixer, a ball mill, a vibration mill, etc. can be used.

The calcination temperature in the calcination step is not particularly limited, but it is preferably in the range of 1800°C or more and 2100°C or less. If the firing temperature is above the above lower limit, the crystal grain growth of the β-type silicon aluminum oxynitride phosphor will proceed more effectively. Therefore, the light absorption rate, internal quantum efficiency, and external quantum efficiency can be made better. If the firing temperature is below the above upper limit, the decomposition of the β-type silicon aluminum oxynitride phosphor can be more suppressed. Therefore, the light absorption rate, internal quantum efficiency, and external quantum efficiency can be made better. Other conditions such as the heating time, heating rate, heating holding time, and pressure in each calcination step are also not particularly limited, and may be appropriately adjusted according to the raw materials used. Typically, the heating holding time is preferably 3 to 30 hours, and the pressure is preferably 0.6 to 10 MPa.

In the calcining step, as far as the calcining method of the mixture is concerned, for example, the mixture can be filled in a container made of a material that does not react with the mixture during calcining (for example, boron nitride), and heated in a nitrogen atmosphere Methods. By using this method, a crystal growth reaction, a solid solution reaction, etc. can proceed, and a β-type silicon aluminum oxynitride phosphor can be obtained.

The calcined product obtained through the calcining step is usually a granular or massive sintered body. It is possible to temporarily pulverize the calcined product by using singly or in combination with treatments such as disintegration, pulverization, and classification. The specific processing method includes, for example, a method of pulverizing the sintered body to a predetermined particle size using a general pulverizer such as a ball mill, a vibration mill, and a jet mill. However, since excessive pulverization may generate particles that easily scatter light, and cause crystal defects on the surface of the particles, which may cause a decrease in luminous efficiency, care must be taken.

･Low-temperature calcination step (annealing step) After the calcination step, it may further include a low temperature calcination step (annealing step) of heating the calcined product (preferably for temporarily pulverized ones) at a lower temperature than the calcination temperature in the calcination step to obtain a low temperature calcined powder. Low-temperature calcination step (annealing step), in passive gas such as rare gas, nitrogen; reducing gas such as hydrogen, carbon monoxide gas, hydrocarbon gas, ammonia gas; or their mixed gas; or non-oxidizing gas other than pure nitrogen in vacuum The environment is more ideal. It is particularly ideal to perform in a hydrogen environment and an argon environment. The low-temperature calcination step (annealing step) can be performed in an atmospheric pressure environment or a pressurized environment. The heat treatment temperature in the low-temperature calcination step (annealing step) is not particularly limited, but it is preferably 1200 to 1700°C, and more preferably 1300 to 1600°C. The time of the low-temperature calcination step (annealing step) is not particularly limited, but is preferably 3 to 12 hours, and more preferably 5 to 10 hours. By performing the low-temperature calcination step (annealing step), the luminous efficiency of the phosphor particles can be sufficiently improved. In addition, the rearrangement of the elements removes strains and defects, so transparency can also be improved. These results are ideal in terms of adjusting It/Ii and Ip/Ii. In the annealing step, there is a possibility of different phases. However, it can be removed by the following acid treatment or the like.

Before the annealing step, a compound of elements constituting the β-type silicon aluminum oxynitride phosphor can also be added and mixed. The compound to be added is not particularly limited, and examples thereof include oxides, nitrides, oxynitrides, fluorides, and chlorides of each element. In particular, by adding silicon dioxide, aluminum oxide, europium oxide, europium fluoride, etc. to each heat treatment, the brightness of the β-type silicon aluminum oxynitride phosphor may be improved. However, in terms of the added raw materials, it is desirable that the remaining part that is not solid-solved can be removed by acid treatment, alkali treatment, etc. after the annealing step.

･Acid treatment steps In the acid treatment step, the low-temperature calcined powder obtained after the low-temperature calcining step (annealing step) is treated with an acid. Thereby, at least a part of impurities that do not contribute to light emission can be removed. As for the acid, an aqueous solution containing one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used. In particular, hydrofluoric acid, nitric acid, and a mixed acid of hydrofluoric acid and nitric acid are preferable. The acid treatment can be performed by dispersing the low-temperature calcined powder in an aqueous solution containing the above-mentioned acid. The stirring time is, for example, 10 minutes or more and 6 hours or less, and preferably 30 minutes or more and 3 hours or less. The temperature during stirring is, for example, 40°C or higher and 90°C or lower, and preferably 50°C or higher and 70°C or lower. After the acid treatment step, it is preferable to separate substances other than the β-type silicon aluminum oxynitride phosphor by filtration, and wash the substances attached to the β-type silicon aluminum oxynitride phosphor with water.

･Crushing step In the pulverization step, the powder after the acid treatment step is pulverized and micronized. In particular, if the pulverization is performed under appropriate conditions, phosphor particles having an It/Ii of 0.41 or less and an Ip/Ii of 0.03 or more can be produced by this. With regard to the pulverization step, it is particularly desirable to perform the powder after the acid treatment step by a ball mill using zirconia balls. By pulverizing at a moderate speed and time, phosphor particles with an It/Ii of 0.41 or less and an Ip/Ii of 0.03 or more can be easily obtained. In particular, it is preferable to add a mixed solution of ethanol and water to perform pulverization by a ball mill. The mixed solution can modify the surface state of the phosphor and prevent the agglomeration of the micronized powder. It is ideal that the volume ratio of the mixed solution is not equivalent to the mixing ratio of dangerous substances in the fire protection law. As an example, the volume ratio of ethanol to water is 1:1.

･Decantation step In the decantation step, the phosphor particles that have been micronized through the pulverization step are put into an appropriate dispersion medium, and the phosphor particles are precipitated. After that, the supernatant was removed. In this way, fine particles that may adversely affect optical properties can be removed, and phosphor particles having an It/Ii of 0.41 or less and Ip/Ii of 0.03 or more can be easily obtained. As the dispersion medium, for example, an aqueous solution of sodium hexametaphosphate or the like can be used. The desired phosphor particles can be obtained by filtering, drying the precipitate obtained in the decantation step, and sieving it as necessary.

＜Composite, light-emitting device and self-luminous display＞ FIG. 1 is a schematic diagram of the light-emitting device 1. The light-emitting device 1 includes a composite body 10 and a light-emitting element 20. The composite body 10 is in contact with and arranged on the upper part of the light-emitting element 20. The light emitting element 20 is typically a blue LED. There are terminals in the lower part of the light-emitting element 20. The terminal can emit light by being connected to a power source. The wavelength of the excitation light emitted from the light-emitting element 20 is converted by the composite 10. When the excitation light is blue light, the blue light is converted into green light by the composite body 10 containing β-type silicon aluminum oxynitride.

The composite body 10 can be composed of the above-mentioned phosphor particles and a sealing material that seals the phosphor particles. As for the sealing material, various curable resins can be used. Any curable resin can be used as long as it is sufficiently transparent and can obtain the optical properties necessary for the display system. As for the sealing material, for example, silicone resin can be cited. In addition to the listed polysiloxane resin OE-6630 manufactured by Toray Dow Corning Corporation and the polysiloxane material manufactured by Shin-Etsu Chemical Co., Ltd., various polysiloxane resins can be used (for example, as a polysiloxane resin for LED lighting and sold) By). In addition to transparency, silicone resin is also ideal from the viewpoint of heat resistance and the like. The amount of phosphor particles in the composite 10 is, for example, 10 to 70% by mass, and preferably 25 to 55% by mass.

The size and shape of the light-emitting element 20 are not particularly limited as long as they meet the definition of Micro LED or Mini LED and can be applied to Micro LED displays or Mini LED displays.

By using the light-emitting device 1 as a pixel (typically, a green pixel), a self-luminous display (Micro LED display or Mini LED display) can be constructed. By combining the light emitting device 1 (Micro LED or Mini LED) that emits green light, the Micro LED or Mini LED that emits blue light, and the Micro LED or Mini LED that emits red light, a self-luminous display that can express colors ( Micro LED display or Mini LED display). Incidentally, for the Micro LED or Mini LED that emits blue light, for example, the composite 10 can be removed from the light-emitting device 1 in FIG. 1 (that is, only the blue LED). In addition, for Micro LEDs or Mini LEDs that emit red light, for example, in the light-emitting device 1 of FIG.

Above, the embodiments of the present invention have been described, but they are examples of the present invention, and various configurations other than those described above can be adopted. In addition, the present invention is not limited to the above-mentioned embodiments, and the present invention includes modifications, improvements, etc. within the scope of achieving the object of the invention. [Example]

The implementation aspects of the present invention will be described in detail based on examples and comparative examples. Just in case, it is stated first that the present invention is not limited to the embodiments.

(Example 1) The phosphor particles of Example 1 were manufactured through the following steps. ･The calcination step of calcining the raw material powder obtained after mixing the starting materials, ･The low-temperature calcination step (annealing step) performed after temporarily pulverizing the calcined product obtained in the calcination step, ･An acid treatment step in which impurities are removed from the low-temperature calcined powder obtained after the low-temperature calcining step, ･Crush the powder after the acid treatment step to perform the pulverization step of micronization, and ･A decantation step to remove the fine powder generated in the pulverization step. Hereinafter, these steps will be described in detail.

･Calcination step Regarding the starting material of the phosphor of Example 1, the silicon nitride was blended and mixed in such a way that the elements were Si: Al: O: Eu = 5.83: 0.18: 0.18: 0.03 in molar ratio. Powder (manufactured by Ube Industries Co., Ltd., SN-E10 grade), aluminum nitride powder (manufactured by Tokuyama Corporation, grade E), alumina powder (manufactured by Daimyung Chemical Co., TM-DAR grade), europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd.) , RU level). In addition, the nitrogen content is determined when the above-mentioned molar ratio is blended to blend the raw materials. In order to fully disperse and mix these various starting materials, they are mixed with a small pulverizing mixer. After that, all the particles were passed through a sieve with a mesh size of 150 μm to remove agglomerates, and this was used as a raw material powder. The raw material powder was filled in a cylindrical boron nitride container with a lid (manufactured by Denki Kagaku Kogyo Co., Ltd.), and calcined at 1900°C for 5 hours in an electric furnace with a carbon heater in a 0.9 MPa pressurized nitrogen atmosphere. The calcined product is obtained through the above steps.

･Low-temperature calcination step (annealing step) The calcined product obtained in the above calcining step is filled into a cylindrical container made of boron nitride. It was kept at 1500°C for 7 hours in an electric furnace equipped with a carbon heater under an atmosphere of argon gas at atmospheric pressure. The low-temperature calcined powder is obtained through the above steps.

･Acid treatment steps The above-mentioned low-temperature calcined powder is immersed in a mixed acid of hydrofluoric acid and nitric acid. Then, it heat-processed at 60 degreeC or more for 3 hours. The heat-treated low-temperature calcined powder is thoroughly washed with pure water, dried, and then passed through a 45 μm sieve to obtain the powder after the acid treatment step (acid-treated powder). In addition, in the calcination step, because oxygen-containing compounds such as SiO generated by the side reaction of the raw material powder are volatilized, the oxygen content in the calcined material obtained in the calcination step is higher than that of the raw material powder. The oxygen content in it tends to decrease, so it sometimes generates β-type silicon-aluminum oxynitride containing oxygen, aluminum, and europium that are not solid-dissolved in the β-type silicon-aluminum oxynitride phosphor after calcination. Compounds other than phosphors (heterophase). Almost all or part of the heterogeneous phase is dissolved and removed by the acid treatment step.

･Crushing step The above-mentioned acid-treated powder is added to a mixed solution of water and ethanol with a volume ratio of 1:1 to prepare a dispersion. A ball mill (zirconia spheres) was used to pulverize this dispersion at a rotation speed of 40 rpm for 14 hours. After that, it is filtered, dried, and passed through a sieve with a nominal mesh of 45 μm to obtain the powder after the pulverization step.

･Decantation step In order to remove the superfine powder from the powder after the acid treatment step, a decantation step is implemented in which the powder after the acid treatment step gradually settles to remove the fine powder of the supernatant liquid, and the obtained precipitate is filtered, dried, and then passed through the mesh 45μm sieve. Finally, the β-type silicon aluminum oxynitride phosphor of Example 1 was obtained. In addition, the decantation operation is based on the Stokes formula to calculate the settling time of phosphor particles with the setting of removing particles with a diameter of 2μm or less. The method of removing the supernatant liquid above the height is implemented. As for the dispersion medium, an aqueous solution containing 0.05% by mass of sodium hexametaphosphate ion-exchanged water is used, and a device that can suck up the upper liquid from a tube to remove the supernatant is used, and the tube is connected to a cylindrical container. A suction port is provided at a predetermined height. The operation of decantation is repeated.

(Examples 2 and 3, and Comparative Examples 1 and 2) The phosphors of Examples 2 and 3 and Comparative Examples 1 and 2, as shown in Table 1, were obtained by changing the pulverization time of the pulverization step (ball mill pulverization) in Example 1. Specifically, in Examples 2 and 3 and Comparative Example 1, the pulverization time of the pulverization step was set to 10 hours, 9 hours, and 5 hours, respectively, as shown in Table 1. In Comparative Example 2, ball milling was not implemented. The steps other than the pulverization step were performed in the same manner as in Example 1, and phosphor particles of Examples 2 and 3 and Comparative Examples 1 and 2 were obtained.

(Example 4) Except that the calcination temperature of the calcination step was set to 2000°C, the calcination time was set to 18 hours, and the pulverization time of the pulverization step was set to 20 hours, the same procedure as in Example 1 was carried out to obtain phosphor particles. .

(Comparative example 3) As shown in Table 1, except that the acid treatment step and the decantation step were not carried out, it was carried out in the same manner as in Example 3 to obtain phosphor particles.

＜Confirmation of crystal structure＞ For the phosphor particles of the Examples and Comparative Examples, an X-ray diffraction device (UltimaIV manufactured by Rigaku Corporation) was used to confirm the crystal structure based on a powder X-ray diffraction pattern using Cu-Kα rays. In the powder X-ray diffraction patterns of the phosphor particles in the Examples and Comparative Examples, the same diffraction pattern as the β-type silicon aluminum oxynitride crystal was recognized. That is, it was confirmed that β-type silicon aluminum oxynitride phosphors were obtained in Examples and Comparative Examples.

D Each phosphor particle of Examples and Comparative Examples <D ₅₀ and D ₉₀ Determination of> ₅₀ and D ₉₀ embodiment, is the line by a laser diffraction - Microtrac MT3300EXII measuring device of particle scattering method (MicrotracBEL (Unit ) Company) to determine. The specific measurement procedure is as follows.

(1) Put 0.5 g of the phosphor into 100 mL of an aqueous solution of ion-exchange water containing 0.05% by mass of sodium hexametaphosphate, and use an ultrasonic homogenizer (Ultrasonic Homogenizer US-150E, Nippon Seiki Manufacturing Co., Ltd., Amplitude100%, oscillation frequency 19.5±1kHz, tip size 20mmφ, amplitude about 31μm) The tip is placed in the center of the liquid and the dispersion treatment is performed for 3 minutes. In this way, a dispersion liquid for measurement is obtained. (2) After that, using the above-mentioned particle size measuring device, the particle size distribution of the phosphor particles in the dispersion liquid for measurement is measured. _{D 50} and D ₉₀ are obtained from the obtained particle size distribution.

＜455nm light absorption rate, internal quantum efficiency, external quantum efficiency, peak wavelength＞ The 455nm light absorption rate, internal quantum efficiency, and external quantum efficiency of each phosphor particle of the Examples and Comparative Examples were calculated by the following procedures.

The phosphor particles of the embodiment and the comparative example were respectively filled into the concave groove in such a way that the surface was smooth, and installed in the opening of the integrating sphere. Using an optical fiber, a monochromatic light from a luminous light source (Xe lamp) and split into a wavelength of 455nm is used as the excitation light of the phosphor to be guided into the integrating sphere. The phosphor sample was irradiated with this monochromatic light, and the fluorescence spectrum of the sample was measured using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). From the obtained spectral data, calculate the number of excited reflected light photons (Qref) and the number of fluorescent photons (Qem). The number of excitation reflected light photons and the number of excitation light photons are calculated within the same wavelength range, and the number of fluorescent photons is calculated within the range of 465 to 800 nm.

In addition, using the same device, a standard reflector (Spectralon (registered trademark) manufactured by Labsphere Corporation) with a reflectivity of 99% was installed in the opening of the integrating sphere, and the spectrum of excitation light with a wavelength of 455 nm was measured. At this time, the number of photons (Qex) of the excitation light from the spectrum in the wavelength range of 450 to 465 nm was calculated. The 455nm light absorption rate and internal quantum efficiency of the phosphor particles of the Examples and Comparative Examples were obtained by the following formulas. 455nm light absorption rate=[(Qex-Qref)/Qex]×100 Internal quantum efficiency = [Qem/(Qex-Qref)]×100 By the way, the external quantum efficiency is obtained by the formula shown below. External quantum efficiency = (Qem/Qex)×100 Therefore, according to the above formula, the external quantum efficiency system has the following relationship. External quantum efficiency = 455nm light absorption rate × internal quantum efficiency

The peak wavelength of the phosphor particles of the Examples and Comparative Examples is defined as the wavelength that shows the highest intensity in the wavelength range of 465nm to 800nm in the spectral data obtained by mounting the phosphor on the opening of the integrating sphere.

＜800nm diffuse reflectance of phosphor particles＞ The diffuse reflectance of the phosphor particles of the Examples and Comparative Examples was measured by installing an integrating sphere device (ISV-469) in an ultraviolet visible spectrophotometer (V-550) manufactured by JASCO Corporation. In the measurement, a standard reflector (Spectralon (registered trademark)) is used for baseline calibration, a solid sample holder filled with phosphor particles is installed, and the diffuse reflectance is measured in the wavelength range of 500 to 850 nm. The 800nm diffuse reflectance in this specification refers to the value of the diffuse reflectance in this measurement, especially at 800nm.

＜600nm light absorption rate of phosphor particles＞ The 600nm light absorption rate of the phosphor particles of the Examples and Comparative Examples was measured by the following procedure. In the opening of the integrating sphere, a standard reflector with a reflectivity of 99% (Spectralon (registered trademark) manufactured by Labsphere) is installed. Monochromatic light from a light source (Xe lamp) and split into a wavelength of 600 nm was introduced into the integrating sphere using an optical fiber, and the reflected light spectrum was measured by a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). At this time, the number of photons of incident light is calculated from the spectrum in the wavelength range of 590 to 610 nm (Qex (600)).

Then, the β-type silicon aluminum oxynitride phosphor is filled into the concave groove in such a way that the surface is smooth, and is installed in the opening of the integrating sphere. After that, it was irradiated with monochromatic light with a wavelength of 600 nm, and the incident reflected light spectrum was measured by a spectrophotometer. Calculate the number of incident reflected light photons (Qref(600)) from the obtained spectral data. The number of incident reflected light photons (Qref(600)) is calculated in the same wavelength range as the number of incident light photons (Qex(600)). The 600nm light absorption rate was calculated from the two types of photon numbers obtained based on the following formula. 600nm light absorption rate=((Qex(600)-Qref(600))/Qex(600))×100

When the standard sample of β-type silicon aluminum oxynitride phosphor (NIMS Standard Green lot No. NSG1301, manufactured by silicon aluminum oxynitride) was measured by the above measurement method, the light absorption rate at 600 nm was 7.6%. If the manufacturer of the measuring device, the manufacturing lot number, etc. change, the value of the 600nm light absorption rate may change. Therefore, when the manufacturer of the measuring device, the manufacturing lot number, etc., change, it will be based on the above-mentioned β-type silicon aluminum The measured value obtained from the standard sample of the nitrogen oxide phosphor is used as the reference value, and each measured value is corrected.

The sheeting of each phosphor and the evaluation of optical properties were performed by the following procedures.

＜Sheet production procedure＞ (1) Using a rotation and revolution mixer, 40 parts by mass of phosphor particles and 60 parts by mass of Toray Dow Corning polysiloxane resin OE-6630 are subjected to stirring treatment and defoaming treatment to obtain a uniform mixture . As for the rotation and revolution mixer, the model ARE-310 manufactured by THINKY is used. In addition, the stirring treatment and the defoaming treatment are specifically after the stirring treatment at a rotation speed of 2000 rpm for 2 minutes and 30 seconds, and then the defoaming treatment at a rotation speed of 2200 rpm for 2 minutes and 30 seconds. (2) The mixture obtained in (1) above is dropped on a transparent fluororesin film (manufactured by Flonchemical Co., Ltd., NR5100-003: 100P), and the transparent fluororesin film is superimposed on the drops. It is formed into an uncured sheet using a roller with a thickness of 2 times the film thickness and a gap of 50μm. (3) The uncured sheet obtained in (2) above was heated at 150°C for 60 minutes, and then the fluororesin film was peeled off to obtain a cured sheet with a film thickness of 50±5 μm.

＜Optical characteristics＞ Using the device schematically shown in Figure 2, the blue light emitted by a blue LED with a peak wavelength in the range of 450nm to 460nm was irradiated on one side of the hardened sheet (set the intensity of the peak wavelength of the blue light as Ii[W/nm]). Then, measure the intensity It[W/nm] of the peak wavelength of the light emitted from the other side of the cured sheet in the range of 450nm to 460nm, and the intensity Ip[W/ nm]. Then, calculate It/Ii and Ip/Ii.

In the above measurement, the following were used for the blue LED. Models, etc.: SMT PLCC-6 0.2W SMD 5050 LED Peak wavelength: 450nm-460nm Chromaticity x: 0.145-0.165 Chromaticity y: 0.023-0.037

In addition, in FIG. 2, the distance between the top surface of the blue LED and the bottom surface of the hardened sheet is 2 mm.

<Measurement of the y value (chromaticity Y) of the hardened sheet> The y value (chromaticity Y) of the cured sheet using the phosphor particles of the embodiment and the comparative example is calculated according to JIS Z 8724 from the wavelength region data in the range of 400 nm to 800 nm of the emission spectrum according to JIS Z 8701 It can be obtained from the y value (chromaticity Y) of the CIE chromaticity coordinate in the specified XYZ color system. It is ideal because the larger the y value, the higher the color gamut of the display (the green area is wider).

The production conditions (including the composition of raw materials) and the evaluation results of the respective Examples and Comparative Examples are summarized and shown in Table 1.

[Table 1] β-SiAlON phosphor Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Example 4 Comparative example 3 Manufacturing conditions Raw material composition (mole ratio) Si 5.83 5.83 5.83 5.83 5.83 5.83 5.83 Al 0.18 0.18 0.18 0.18 0.18 0.18 0.18 O 0.18 0.18 0.18 0.18 0.18 0.18 0.18 Eu 0.03 0.03 0.03 0.03 0.03 0.03 0.03 Calcining temperature (°C) 1900 1900 1900 1900 1900 2000 2000 Calcining time (h) 5 5 5 5 5 18 18 Annealing temperature (°C) 1500 1500 1500 1500 1500 1500 1500 Annealing time (h) 7 7 7 7 7 7 7 Acid treatment, filtration, pure water washing Implement Implement Implement Implement Implement Implement Not implemented Ball milling Time(h) 14 10 9 5 Not implemented 20 20 Speed (rpm) 40 40 40 40 Not implemented 40 40 Decantation Implement Implement Implement Implement Implement Implement Not implemented Filter and dry Implement Implement Implement Implement Implement Implement Implement Evaluation It/Ii 0.22 0.392 0.40 0.43 0.56 0.18 0.23 Ip/Ii 0.086 0.080 0.077 0.070 0.040 0.083 0.029 D ₅₀ (μm) 3.4 4.9 5.1 9.2 12.0 2.1 1.7 D ₉₀ (μm) 6.4 9.1 9.7 15.5 17.5 4.5 3.9 800nm diffuse reflectance (%) 94.9 96 95.7 99.7 97.5 92 84 600nm absorption rate (%) 7.5 7.9 8.9 4.8 4.9 7.5 11.0 455nm light absorption rate (%) 52.1 63.7 65 68.6 74.9 44 38 Internal quantum efficiency (%) 69.3 74.8 75.6 78.1 80 58 47 External quantum efficiency (%) 36.1 48 49 53.6 60 26 18 Peak wavelength (nm) 542.5 543.3 543 543.8 544.3 542.4 541.9 y value 0.296 0.232 0.198 0.164 0.137 0.309 0.187

As shown in Table 1, in an embodiment where It/Ii is 0.41 or less and Ip/Ii is 0.03 or more, a large y value can be obtained. That is to say, the phosphor particles of the embodiment are ideally used in the aspect of high color gamut of Micro LED display or Mini LED display. On the other hand, in the comparative example where It/Ii exceeds 0.41 and/or Ip/Ii is less than 0.03, the value of y is smaller than that of the examples. Just in case, the y value of Example 3 is 0.198, and the y value of Comparative Example 3 is 0.187. This gap may be considered to be a small gap at first glance, but in the high color gamut of the display In the subject, this gap is a big gap.

By the way, it can be seen from the examples and comparative examples described in Table 1 that even if the same raw materials are used, it/Ii and Ip/Ii will still change depending on the presence or absence of acid treatment, the conditions (time) of ball milling and the presence or absence of decantation. Has changed. Therefore, it can be understood that by selecting appropriate raw materials and selecting appropriate manufacturing conditions, phosphor particles with an It/Ii of 0.41 or less and Ip/Ii of 0.03 or more can be obtained.

This application claims priority based on Japanese Patent Application No. 2020-053228 filed on March 24, 2020, and incorporates all its disclosures into the present invention.

1: Light-emitting device 10: Complex 20: Light-emitting element

[Figure 1] is a schematic diagram of the light-emitting device. [Fig. 2] is a diagram for supplementary explanation of the evaluation method in the examples.

1: Light-emitting device

10: Complex

20: Light-emitting element

Claims (7)

A kind of phosphor particles, which are phosphor particles for Micro LED or Mini LED made of β-type silicon aluminum oxynitride, The hardened sheet made by the following sheet production process meets the following optical characteristics; ＜Sheet production procedure＞ (1) Using a rotating and revolving mixer, 40 parts by mass of the phosphor particles and 60 parts by mass of Toray Dow Corning polysiloxane resin OE-6630 are subjected to stirring and defoaming treatment to obtain a uniform mixture; (2) Obtain a sheet in which the mixture obtained in (1) is dropped on a transparent first fluororesin film, and then a transparent second fluororesin film is superimposed on the drops, and the sheet is The object is formed into an uncured sheet using a roller having the total thickness of the first fluororesin film and the second fluororesin film plus a gap of 50μm; (3) The uncured sheet obtained in (2) was heated at 150°C for 60 minutes, and then the first fluororesin film and the second fluororesin film were peeled off to obtain a cured film with a thickness of 50±5μm Sheet; ＜Optical characteristics＞ When the intensity of the blue light emitted by the blue LED with a peak wavelength in the range of 450nm to 460nm at the peak wavelength is Ii [W/nm], and the blue light is irradiated on one side of the hardened sheet The intensity of the peak wavelength of the light emitted from the other side of the cured sheet in the range of 450nm to 460nm is It[W/nm] and the intensity of the peak wavelength in the range of 500nm to 560nm is Ip[W/nm ]Time, It/Ii is 0.41 or less, and Ip/Ii is 0.03 or more. Such as the phosphor particles of claim 1, wherein the composition of the β-type silicon aluminum oxynitride is based on the general formula Si _12-a Al _a O _b N _16-b : Eu _x (0＜a≦3; 0＜ b≦3; 0＜x≦0.1), and let the cumulative 50% particle size measured by the laser diffraction scattering method on the volume basis and the cumulative 90% particle size on the volume basis be D ₅₀ and D ₉₀ respectively, D ₅₀ is 5μm or less, D ₉₀ is 10μm or less; However, D ₅₀ and D ₉₀ are used to put 0.5 g of the phosphor particles into 100 ml of an ion-exchange aqueous solution mixed with sodium hexametaphosphate 0.05% by mass, and use it An ultrasonic homogenizer with an oscillation frequency of 19.5 ± 1 kHz and an amplitude of 31 ± 5 μm. The tip is placed in the center of the liquid and subjected to a dispersion treatment for 3 minutes. The measured value of the liquid is obtained. Such as the phosphor particles of claim 1 or 2, in which, The diffuse reflectance of light with a wavelength of 800 nm is 85% or more. Such as the phosphor particles of claim 1 or 2, in which, The light absorption rate for light with a wavelength of 600 nm is 10% or less. A composite body is provided with the phosphor particles according to any one of claims 1 to 4, and a sealing material for sealing the phosphor particles. A light-emitting device is provided with a light-emitting element that emits excitation light, and a composite body according to claim 5 that converts the wavelength of the excitation light. A self-luminous display is provided with the light-emitting device as claimed in claim 6.

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