Phosphor powder, phosphor resin composition, phosphor, light-emitting element, and light-emitting device

Abstract

Provided are a phosphor powder that exhibits high absorptivity for blue light, as well as a phosphor resin composition, a phosphor, a light-emitting element, and a light-emitting device that contain the phosphor powder. The phosphor powder has a maximum fluorescence intensity (Imax) in an excitation spectrum that exhibits a fluorescence intensity at a maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is a fluorescence wavelength that provides a maximum fluorescence intensity for an excitation light having a wavelength of 450 nm) in a range of 380 nm to 420 nm. 380-420 ) and the fluorescence intensity (I 450 ) and the ratio (I 450 / I 380-420 ) is 0.88 or more.

Description

[Technical field]

[0001] The present invention relates to a phosphor powder, a phosphor resin composition, a phosphor, a light-emitting element, and a light-emitting device. [Background technology]

[0002] Light-emitting devices that use light-emitting diodes (LEDs) that emit near-ultraviolet or blue light as a light source (excitation source) and combine this with a phosphor are widely used in various light-emitting devices such as lighting, backlights for mobile devices, and displays.

[0003] In this light-emitting device, the phosphor absorbs the light emitted by the LED (radiated light) and emits light of a different wavelength from the absorbed light. Therefore, it is possible to obtain light emission of a different color tone from the LED radiation light. For example, green light, red light, or white light can be obtained by combining a blue-emitting LED (blue LED) with a green phosphor and / or red phosphor.

[0004] For example, Patent Document 1, which discloses applications of phosphors for LEDs, discloses a white light-emitting element that includes a light-emitting diode that emits blue light, a thiogallate-based green phosphor that emits green light, and an alkaline earth metal sulfide-based red phosphor that emits red light, and that emits white light by mixing the green light and the red light with a part of the blue light (claim 3 of Patent Document 1). It is also described that the white light-emitting element is used as a backlight source for lighting, notebook computers, etc. (

[0002] of Patent Document 1).

[0005] Turning our attention to displays, another application of phosphors, mini LED displays and micro LED displays have been attracting attention in recent years as display technology advances. In micro LED displays, each of the sub-pixels R (red), G (green), and B (blue) is composed of an independent LED, and compared to LCD panels, they have the advantage of being able to realize images with higher brightness and a higher contrast ratio, with faster response speeds and lower power consumption. In addition, compared to OLED displays, they have the advantage of being able to display images with higher brightness and no burn-in caused by deterioration.

[0006] Regarding a micro LED display, Patent Document 2 discloses a micro LED display device including a micro LED driving substrate and a micro LED panel (Claim 1 of Patent Document 2).

[0007] The development of phosphor materials (fluorescent materials) applicable to these applications is also progressing. For example, Patent Document 3 describes a phosphor having a maximum emission wavelength of 500 nm to 600 nm and a half-width of 46 nm or less, represented by the following formula: Sr 1-x Ga2S4:Eu x (where 0.10≦x≦0.20) is disclosed (claim 1 of Patent Document 3). It is also disclosed that the green-emitting phosphor can emit light with high color purity and can be used as a backlight source for display devices and as a light source for illumination (claim 2 of Patent Document 3).

[0008] and

[0052] ). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5052507 [Patent Document 2] JP 2018-182282 A [Patent Document 3] JP 2020-139056 A Summary of the Invention [Problem to be solved by the invention]

[0009] Thus, although LED phosphors and materials thereof are used for various purposes, it is generally desired that the emitted color is excellent, that is, that the inclusion of any emission color other than that required is suppressed. If any unnecessary color is mixed in, it becomes difficult to obtain the desired color tone and clear image when a light emitting device is constructed. In order to obtain an excellent emitted color, it is important that the emission spectrum (fluorescence spectrum) is narrow and does not transmit blue light, and for this purpose, a phosphor that shows a high absorptivity (Abs.) for blue light is desired. Here, absorptivity is the ratio of light absorbed by the phosphor out of the irradiated light.

[0010] For example, as shown in Figure 1, the phosphor for a micro LED display is ideal for all of the blue light emitted by the LED to be absorbed and excited by a phosphor layer made of a green phosphor and a phosphor layer made of a red phosphor, thereby converting the color. In addition, the thickness of the phosphor layer is small, at several tens to several hundreds of μm. Therefore, even if the phosphor layer is thin, it is necessary to sufficiently absorb the emitted light (excitation light), and for this purpose, it is particularly important to increase the absorption rate of the phosphor.

[0011] However, conventional fluorescent materials for LEDs are inadequate in meeting this demand.

[0012] The present inventors have conducted research in light of such conventional problems, and have found that, in phosphor powders (powdered fluorescent materials), there is a relationship between the fluorescence intensity ratio and the absorptance at a specific excitation wavelength in the excitation spectrum, and that by increasing this fluorescence intensity ratio, it is possible to increase the absorptance of blue light.

[0013] The present invention has been completed based on these findings, and an object of the present invention is to provide a phosphor powder that exhibits high absorptivity for blue light. Another object of the present invention is to provide a phosphor resin composition, a phosphor, a light-emitting element, and a light-emitting device that contain the phosphor powder. [Means for solving the problem]

[0014] The present invention encompasses the following aspects (1) to (15). In this specification, the expression "to" includes both ends of the expression. In other words, "X to Y" is synonymous with "X or more and Y or less."

[0015] (1) In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is the fluorescence wavelength that produces the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity (I 450 ) and the ratio (I 450 / I 380-420 ) is 0.88 or more.

[0016] (2) In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is the fluorescence wavelength that produces the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I 330-360 ) and the fluorescence intensity (I 450 ) and the ratio (I 450 / I 330-360 ) is 0.93 or more.

[0017] (3) In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is the fluorescence wavelength that provides the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), Fluorescence intensity (I 450 ) and the fluorescence intensity (I 500 ) and the ratio (I 450 / I 500 ) is 1.4 or more and 2.2 or less.

[0018] (4) In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is the fluorescence wavelength that produces the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity (I 250 ) and the ratio (I 380-420 / I 250 ) is 2.7 or more.

[0019] (5) The phosphor powder is any one of the phosphor powders (1) to (4) above, which contains a matrix compound crystal and a luminescent center element.

[0020] (6) The phosphor powder according to (5) above, wherein the concentration ratio of the luminescent center element is 8.0 mol % or more and 50 mol % or less.

[0021] (7) The phosphor powder according to (5) or (6) above, wherein the matrix compound contains a sulfide-based fluorescent material.

[0022] (8) The phosphor powder according to any one of (5) to (7) above, wherein the base compound contains at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga) and sulfur (S).

[0023] (9) The phosphor powder according to any one of the above (5) to (8), wherein the base compound has a basic composition of (Ba, Sr)Ga2S4.

[0024] (10)(Ba,Sr) 1-x Ga2S4:Eu x (x≦0.08≦x≦0.50) (wherein 0.08≦x≦0.50)

[0025] (11) The phosphor powder according to any one of (1) to (10) above, which has an absorptivity of 65% or more for excitation light having a wavelength of 450 nm.

[0026] (12) A phosphor resin composition comprising a phosphor powder according to any one of (1) to (11) above and a resin.

[0027] (13) A phosphor comprising the phosphor resin composition according to (12) above.

[0028] (14) A light-emitting device comprising the phosphor according to (13) above and an excitation source.

[0029] (15) A light-emitting device comprising the light-emitting element according to (14) above. Effect of the Invention

[0030] According to the present invention, there is provided a phosphor powder exhibiting high absorptivity for blue light. Also, according to the present invention, there are provided a phosphor resin composition, a phosphor, a light-emitting element, and a light-emitting device, each containing the phosphor powder. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram for explaining a phosphor for a micro LED display. [Diagram 2] 1 shows the excitation spectra of the phosphor powders of Examples 1 to 3. [Diagram 3] 3 shows the excitation spectra of the phosphor powders of Examples 4 to 6. [Figure 4] 3 shows the excitation spectra of the phosphor powders of Examples 7 and 8. [Diagram 5] 3 shows the excitation spectra of the phosphor powders of Comparative Examples 1 to 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] A specific embodiment of the present invention (hereinafter, referred to as the present embodiment) will be described. Note that the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the present invention.

[0033] <<1. Phosphor powder>> The phosphor powder of this embodiment encompasses one or more of the following first to fourth aspects.

[0034] <First aspect> The phosphor powder in the first embodiment has a maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity (I 450 ) and the ratio (I 450 / I 380-420 ) is 0.88 or more. Here, the maximum fluorescence wavelength λmax is the fluorescence wavelength that provides the maximum fluorescence intensity for excitation light of a wavelength of 450 nm. In other words, in the excitation spectrum showing the fluorescence intensity of the maximum fluorescence wavelength λmax (where the maximum fluorescence wavelength λmax is the fluorescence wavelength that provides the maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light of a wavelength of 450 nm), the maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity at an excitation light wavelength of 450 nm (I 450 ) and the ratio (I 450 / I 380-420 ) is 0.88 or more.

[0035] Fluorescence intensity ratio (I 450 / I 380-420 ), the absorption rate of blue light is increased, and as a result, the transmission of blue light can be suppressed. This is because the luminescent center element (Eu 2+ There are multiple energy levels in the nucleus, but the nucleus is located at an energy of 450 nm. 7 The proportion of F3 states 7 F6 and 7 It is presumed that this is because the absorption rate of blue light increases when the fluorescence intensity is increased above F5. 450 / I 380-420 ) was used as an indicator because the emission wavelength of blue LEDs, which are most commonly used as excitation sources for LED phosphors, is 450 nm.

[0036] Moreover, the fluorescence intensity ratio (I 450 / I 380-420By increasing the fluorescence intensity ratio (I 450 / I 380-420 By increasing the fluorescence intensity ratio (I 450 / I 380-420 The fluorescence intensity ratio (I 450 / I 380-420 The upper limit of the fluorescence intensity ratio (I 450 / I 380-420 ) is preferably 0.88 or more and 1.00 or less, and more preferably 0.91 or more and 1.00 or less.

[0037] Fluorescence intensity ratio (I 450 / I 380-420 ) can be obtained by the following procedure. First, a spectrofluorometer is used to analyze the phosphor powder to obtain a fluorescence spectrum (emission spectrum; PL spectrum). A fluorescence spectrum is a spectrum of fluorescence intensity obtained by fixing the excitation light wavelength at a specific value and scanning the fluorescence wavelength. By examining the fluorescence spectrum, it is possible to determine which wavelength of light emitted by the phosphor is the most intense. Then, in the obtained fluorescence spectrum, the wavelength that produces the maximum (maximum) fluorescence luminosity (maximum fluorescence wavelength λmax) is obtained. For phosphor powder that emits green light (green phosphor powder), λmax is typically in the range of 490 nm to 550 nm (for example, 535 nm).

[0038] Next, the phosphor powder is analyzed using a spectrofluorometer to obtain an excitation spectrum (PLE spectrum). The excitation spectrum is a spectrum of fluorescence intensity obtained by fixing the fluorescence wavelength (the emission wavelength emitted from the phosphor) to a specific value and scanning the wavelength of the excitation light incident on the phosphor. By examining the excitation spectrum, it is possible to confirm which wavelength will cause the strongest fluorescence emission, that is, the optimal excitation wavelength. In this embodiment, the excitation spectrum is obtained by fixing the fluorescence wavelength to the maximum fluorescence wavelength λmax.

[0039] Then, in the obtained excitation spectrum, the maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity (I 450 ) is calculated. Here, the maximum fluorescence intensity (I 380-420 ) is the maximum fluorescence intensity when the excitation light wavelength is in the range of 380 nm to 420 nm. 450 ) is the fluorescence intensity when the excitation light wavelength is 450 nm. And the obtained I 380-420 and I 450 From this, the fluorescence intensity ratio (I 450 / I 380-420 ) is calculated.

[0040] <Second aspect> The phosphor powder in the second embodiment has a maximum fluorescence intensity (I 330-360 ) and the fluorescence intensity (I 450 ) and the ratio (I 450 / I 330-360 ) is 0.93 or more. Here, the maximum fluorescence wavelength λmax is as explained in the first embodiment. In addition, the maximum fluorescence intensity (I 330-360) is the maximum fluorescence intensity within the excitation light wavelength range of 330 nm to 360 nm. In other words, the maximum fluorescence intensity (I) is the maximum fluorescence intensity (I) with excitation light within the wavelength range of 330 nm to 360 nm in the excitation spectrum showing the fluorescence intensity of the maximum fluorescence wavelength λmax (where the maximum fluorescence wavelength λmax is the fluorescence wavelength that produces the maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light of 450 nm wavelength). 330-360 ) and the fluorescence intensity at an excitation light wavelength of 450 nm (I 450 ) and the ratio (I 450 / I 330-360 ) is 0.93 or greater.

[0041] Fluorescence intensity ratio (I 450 / I 330-360 ), the absorption rate of blue light is further increased. This is because the luminescent center element (Eu 2+ There are multiple 5d orbitals in the 5d orbitals, but in particular, the maximum fluorescence intensity (I 330-360 ) affecting 5d xy ,5d x^2-y^2 The fluorescence intensity (I 450 ) affecting 5d Z^2 It is speculated that the reason for this is that the absorption rate of blue light increases when the proportion of 450 / I 330-360 The fluorescence intensity ratio (I) is more preferably 0.95 or more, and even more preferably 0.96 or more. 450 / I 330-360 The upper limit of the fluorescence intensity ratio (I 450 / I 330-360 ) is preferably 0.93 or more and 2.00 or less, more preferably 0.95 or more and 2.00 or less, and even more preferably 0.96 or more and 2.00 or less.

[0042] <Third aspect> The phosphor powder in the third embodiment has a fluorescence intensity (I 450 ) and the fluorescence intensity (I 500 ) and the ratio (I450 / I 500 ) is 1.4 or more and 2.2 or less. Here, the maximum fluorescent wavelength λmax is as explained in the first embodiment. That is, in the excitation spectrum showing the fluorescent intensity of the maximum fluorescent wavelength λmax (wherein the maximum fluorescent wavelength λmax is the fluorescent wavelength that brings about the maximum fluorescent intensity in the emission spectrum (fluorescence spectrum) measured with excitation light of a wavelength of 450 nm), the fluorescent intensity (I 450 ) and the fluorescence intensity at an excitation light wavelength of 500 nm (I 500 ) and the ratio (I 450 / I 500 ) is greater than or equal to 1.4 and less than or equal to 2.2.

[0043] Fluorescence intensity ratio (I 450 / I 500 ) within the aforementioned range, the absorptance of blue light is further increased. The reason for this is that the wavelength of 500 nm overlaps with the emission wavelength of the green phosphor. In other words, if the absorptance at this wavelength (500 nm) becomes high, the phosphor will reabsorb the converted light, lowering the luminescence performance. For this reason, it is presumed that the excitation intensity at 500 nm needs to be appropriately lower than that at 450 nm. From the viewpoint of increasing the absorptance, it is necessary to set the fluorescence intensity ratio (I 450 / I 500 ) is more preferably 1.6 or more and 2.0 or less.

[0044] <Fourth aspect> The phosphor powder in the fourth embodiment has a maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity (I 250 ) and the ratio (I 380-420 / I 250) is 2.7 or more. Here, the maximum fluorescence wavelength λmax is as explained in the first embodiment. That is, in the excitation spectrum showing the fluorescence intensity of the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is the fluorescence wavelength that gives the maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light of a wavelength of 450 nm), the maximum fluorescence intensity (I 380-420 ) and the fluorescence intensity at an excitation light wavelength of 250 nm (I 250 ) and the ratio (I 380-420 / I 250 ) is 2.7 or higher.

[0045] Fluorescence intensity ratio (I 380-420 / I 250 By limiting the wavelength of blue light to within the range mentioned above, the absorption rate of blue light is further increased. The reason for this is that the 250 nm region corresponds to the excitation band of the parent compound, and the luminescent center element (Eu 2+ It is speculated that the higher the concentration of the excited parent compound, the lower the probability of the parent compound being excited. 380-420 / I 250 The fluorescence intensity ratio (I 380-420 / I 250 The upper limit of the fluorescence intensity ratio (I 380-420 / I 250 ) is preferably 2.7 or more and 5.0 or less, more preferably 2.8 or more and 5.0 or less, and even more preferably 2.9 or more and 5.0 or less.

[0046] The phosphor powder of this embodiment satisfies at least one of the requirements defined in the first to fourth aspects described above. That is, it may satisfy only one of them, or it may satisfy two or more of them, or it may satisfy all of them. When it satisfies two or more of them, it is sufficient to satisfy any two or more of the first to fourth aspects in combination.

[0047] The phosphor powder of this embodiment is not limited in its material composition as long as it exhibits fluorescent properties. The phosphor powder is made of a fluorescent material, and generally contains a crystal of a host compound and a luminescent center element (activator). Known fluorescent materials include oxide-based, sulfide-based, oxysulfide-based, nitride-based, and oxynitride-based materials, and any of these may be used.

[0048] For example, oxide-based fluorescent materials include (Y, Gd, Lu)3(Al, Ga)5O 12 :Ce 3+ , (Ba,Sr,Ca)2SiO4:Eu 2+ , (Ba,Sr,Ca)3MgSi2O8:Eu 2+ , CaAl 12 O 19 :Mn 4+ , Ca3Sc2Si3O 12 :Ce 3+ , CaSc2O4:Ce 3+ , (Ba,Sr)3SiO5:Eu 2+ , Li2SrSiO4:Eu 2+ , Ba9Sc2Si6O 24 :EU 2+ , Ca3Si2O7:Eu 2+ , LiSrPO4:Eu 2+ , CaLa4Si3O 13 :EU 3+ , Ba2Gd3Li3Mo8O 32 :EU 3+ and BaMgAl 10 O 17 :EU 2+ ,Mn 2+ etc.

[0049] Sulfide-based fluorescent material: (Ba,Sr,Ca)Ga2S4:Eu 2+ , (Ba,Sr,Ca)Ga2S4:Ce 3+ , (Sr,Ca)S:Eu 2+ , (Sr,Cd)S:Eu 2+ and ZnS:Cu.

[0050] (La,Y)2O2S:Eu as an oxysulfide fluorescent material 3+and La(Ca,Sr)Ga3S6O:Eu 2+ etc.

[0051] (Ba,Sr,Ca)2Si5N8:Eu as a nitride-based fluorescent material 2+ , (Ba,Ca,Sr)AlSiN3:Eu 2+ , La3Si6N 11 :Ce 3+ , (Ba,Sr,Ca)LiAl3N4:Eu 2+ , Sr(Mg3SiN4):Eu 2+ and (Ba,Sr)2Si5N8:Eu 2+ etc.

[0052] As oxynitride-based fluorescent materials, Eu-containing α-type sialon, Eu-containing β-type sialon, Ba9Sc3Si6O 21 N3:Eu 2+ , Ba3Si6O 12 N2:Eu 2+ , BaSi2O2N2:Eu 2+ and (Ba,Sr,Ca)AlSi(ON)3:Eu 2+ etc.

[0053] Other fluorescent materials include Sr 10 (PO4)6C 12 :EU 2+ and K2(Si,Ge,Ti)F6:Mn 4+ etc.

[0054] According to a preferred embodiment, the phosphor powder, as in the composition listed above for the sulfide-based fluorescent material, includes a base compound containing at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga) and sulfur (S), and a luminescent center element. More preferably, the base compound has a basic composition of (Ba,Sr)Ga2S4. Preferably, the luminescent center element includes at least one element selected from the group consisting of europium (Eu), cerium (Ce), manganese (Mn) and samarium (Sm). From the viewpoint of increasing the internal quantum efficiency (IQE) upon excitation by blue light generated from an LED, the luminescent center element preferably includes Eu, and a divalent ion of Eu (Eu 2+ ), more preferably Eu 2+ It is even more preferred that the composition contains only

[0055] On the premise that the phosphor powder satisfies the requirements for the fluorescence intensity ratio defined in the above-mentioned first to fourth aspects, the content of the luminescent center element in the phosphor powder is not limited. However, from the viewpoint of more reliably and easily satisfying the above-mentioned requirements, it is preferable that the luminescent center element is solid-dissolved at a high concentration in the phosphor powder. By dissolving the luminescent center element at a high concentration, a high fluorescence intensity ratio (I 450 / I 380-420 It is possible to realize the desired light absorption rate and light absorption coefficient. Regardless of the composition of the phosphor powder, the concentration ratio of the luminescent center element is preferably 8.0 mol % or more and 50 mol % or less. Here, the concentration ratio of the luminescent center element is the ratio (XA / (XM+XA)) of the molar amount of the luminescent center element (XA) to the sum of the molar amount of the host compound (XM) and the molar amount of the luminescent center element (XA) contained in the phosphor powder. The higher the concentration ratio of the luminescent center element, the higher the ratio (I 450 / I 380-420) becomes high, and as a result, the absorptance of blue light becomes high. From the viewpoint of increasing the absorptance, the concentration ratio is preferably 12 mol% or more, and more preferably 13 mol% or more. On the other hand, if the concentration ratio becomes too high, the luminescence center element cannot be completely dissolved in the base compound, and a heterogeneous phase may be generated. The generation of the heterogeneous phase may cause problems such as a decrease in luminescence intensity. From the viewpoint of suppressing the generation of the heterogeneous phase, the concentration ratio is preferably 45 mol% or less, and more preferably 40 mol% or less. From the viewpoint of suppressing the generation of the heterogeneous phase while increasing the absorptance, the concentration ratio is preferably 12 mol% or more and 45 mol% or less, and more preferably 13 mol% or more and 40 mol% or less.

[0056] According to a preferred embodiment, the phosphor powder is (Ba,Sr) 1-x Ga2S4:Eu x (wherein 0.08≦x≦0.50). This phosphor powder contains a thiogallate compound as a base compound and europium (Eu) as a luminescent center element, and emits green light when excited by excitation light having a wavelength in the near ultraviolet region to the blue region (approximately 300 nm to 510 nm). In addition, since it contains the luminescent center element (Eu) at a relatively high concentration, it is possible to exhibit high absorptance for blue light. From the viewpoint of increasing absorptance, the Eu amount x is preferably 0.12 or more, and more preferably 0.13 or more. From the viewpoint of suppressing the formation of a different phase, x is preferably 0.45 or less, and more preferably 0.40 or less. From the viewpoint of suppressing the formation of a different phase while increasing absorptance, the Eu amount x is preferably 0.12 or more and 0.45 or less, and more preferably 0.13 or more and 0.40 or less.

[0057] According to a further preferred embodiment, the phosphor powder is (Ba y Sr 1-y ) 1-x Ga z S4:Eu x(wherein 0.08≦x≦0.50, 0.00≦y≦1.00, 1.5≦z≦2.5). This phosphor powder contains a relatively high concentration of the luminescent center element (Eu), and is therefore capable of exhibiting high absorptance for blue light. From the viewpoint of increasing absorptance, the Eu amount x is preferably 0.12 or more, and more preferably 0.13 or more. From the viewpoint of suppressing the formation of a different phase, x is preferably 0.45 or less, and more preferably 0.40 or less. From the viewpoint of increasing absorptance, the Ba amount y is preferably 0.50 or less, and more preferably 0.30 or less. From the viewpoint of suppressing the formation of a different phase, the Ga amount z is preferably 1.7 or more and 2.3 or less.

[0058] The phosphor powder may or may not have a coating layer. By providing a coating layer, durability such as moisture resistance can be improved. From the viewpoint of improving durability while maintaining good luminescence properties of the phosphor, the coating layer is preferably made of one or more inorganic compounds such as oxides containing silicon dioxide (SiO2), zinc oxide (ZnO), aluminum oxide (Al2O3), titanium oxide (TiO2), and / or boron (B) or metal sulfates such as barium sulfate (BaSO4).

[0059] The phosphor powder may contain components other than the fluorescent material, such as a flux component, such as a sintering aid, which is added during the synthesis of the phosphor powder.

[0060] The phosphor powder of this embodiment has a high absorptivity of blue light, and therefore has a high absorptivity of blue light. As a result, the emission spectrum (fluorescence spectrum) is narrow and the emission color is excellent. From the viewpoint of obtaining a better emission color, the higher the absorptivity of the excitation light with a wavelength of 450 nm, the more preferable. Specifically, the absorptivity is preferably 65% ​​or more, more preferably 69% or more, and even more preferably 75% or more. The upper limit of the absorptivity is not limited. It is sufficient if it is 100% or less. However, in some applications such as lighting and mini LED displays, it may not be necessary to increase the absorptivity to 100%. In such a case, the absorptivity may be 95% or less. The absorptivity is preferably 65% ​​or more and 100% or less, more preferably 69% or more and 100% or less, and even more preferably 75% or more and 95% or less.

[0061] <<2. Manufacturing method of phosphor powder>> The phosphor powder of this embodiment is not limited in its manufacturing method, provided that it satisfies the above-mentioned requirements. However, it is preferable to manufacture the phosphor powder by a method that dissolves the luminescent center element in the base compound at a high concentration, increases the crystallinity of the base compound, and further reduces distortion. A specific preferable manufacturing method includes a step of mixing raw materials to prepare a raw material mixture (raw material mixing step), and a step of firing the obtained raw material mixture (firing step). In addition, from the viewpoint of easily realizing the promotion of the solid solution of the luminescent center element and the improvement of the crystallinity of the base compound, it is preferable to make the temperature rise rate small (slow) when firing the raw material mixture, and to raise the firing temperature to a certain degree. When the phosphor powder is (Ba, Sr) 1-x Ga2S4:Eu x A preferred production method will be described in detail below, taking as an example a case where the composition is expressed as (where 0.08≦x≦0.50).

[0062] <Raw material mixing process> In the raw material mixing process, the raw materials are mixed to create a raw material mixture. The phosphor powder is (Ba, Sr) 1-x Ga2S4:Eu xIn the case of a composition represented by the formula (1), a barium (Ba) raw material, a strontium (Sr) raw material, a gallium (Ga) raw material, a europium (Eu) raw material, and, if necessary, a sulfur (S) raw material are weighed and mixed. The mixing ratio of the raw materials is determined so that the composition of the phosphor powder finally obtained is (Ba,Sr) 1-x Ga2S4:Eu x (where 0.08≦x≦0.50). The raw material may contain only one of the elements (constituent elements) that make up the phosphor powder, or may contain a combination of multiple constituent elements. When a solid component is used as the sulfur raw material, the sulfur raw material may be mixed. When a gas component is used as the sulfur raw material, the sulfur raw material does not need to be mixed.

[0063] Examples of the barium raw material and the strontium raw material include oxides, sulfides, double oxides, and / or carbonates of the respective elements. Examples of the gallium raw material include oxides (Ga2O3, GaO). Examples of the sulfur raw material include strontium sulfide (SrS), barium sulfide (BaS), sulfur (S), silicon sulfide (SiS2), cerium sulfide (Ce2S3), and / or hydrogen sulfide (H2S) gas. Examples of the europium raw material include europium fluoride (EuF3), europium oxide (Eu2O3), and / or europium chloride (EuCl3).

[0064] In order to adjust the emission wavelength of the phosphor powder and improve the external quantum efficiency (EQE), rare earth elements such as praseodymium (Pr) and samarium (Sm) may be added to the raw material. In order to improve the excitation efficiency, at least one element selected from rare earth elements such as scandium (Sc), lanthanum (La), gadolinium (Gd), and lutetium (Lu) may be added to the raw material as a sensitizer. However, it is preferable that the amount of each of these elements added is 5 mol % or less relative to strontium (Sr). By keeping the content of these elements at 5 mol % or less, it is possible to prevent a large amount of heterophase from precipitating and a significant decrease in brightness. In addition, alkali metal elements and silver ions (Ag +Monovalent cations such as Cr, Cl, F, and I, and halogen ions such as chlorine (Cl), fluorine (F), and iodine (I) may be added to the raw material as charge compensation agents. In terms of charge compensation effect and brightness, the amount of the charge compensation agent added is preferably approximately equal to the content of the aluminum group element or rare earth element.

[0065] The raw material mixing method is not limited. Either a dry method or a wet method may be used. In the case of dry mixing, for example, zirconia balls are used as a medium to mix with a mixer such as a paint shaker or a ball mill, and if necessary, dried to prepare a raw material mixture. In the case of wet mixing, for example, a solvent such as water is added to the raw materials to prepare a suspension, and zirconia balls are used as a medium to mix with a mixer such as a paint shaker or a ball mill, and the media is separated using a sieve or the like, and the solvent is removed from the suspension by a drying method such as reduced pressure drying or vacuum drying.

[0066] The resulting raw material mixture is then fired to produce a fired product. If necessary, the raw material mixture may or may not be pulverized, classified, and / or dried before firing.

[0067] Luminescent center element (Eu 2+ From the viewpoint of promoting the dissolution of the elements (e.g., etc.) and improving the crystallinity of the matrix compound, it is preferable to reduce the heating rate when firing the raw material mixture and to raise the firing temperature to a certain degree. If the heating rate is too high or the firing temperature is too low, the solid solution of the luminescent center element does not proceed, and a different phase may remain in the finally obtained phosphor powder. In addition, the crystallinity of the matrix compound may decrease and distortion may remain. On the other hand, if the heating rate is too low or the firing temperature is too high, the time required for the process may increase and the productivity may decrease. In addition, the constituent elements in the raw material mixture may volatilize, causing a composition deviation of the phosphor powder. The heating rate is preferably 0.05°C / min or more and 5°C / min or less, more preferably 0.1°C / min or more and 0.4°C / min or less. The firing temperature is preferably 900°C or more and 1200°C or less, more preferably 1050°C or more and 1150°C or less. The firing retention time is preferably 24 hours or more and 168 hours or less.

[0068] The firing atmosphere may be an inert gas or a reducing gas, etc. Examples of the firing atmosphere include an argon atmosphere, a nitrogen atmosphere, a sulfur atmosphere, an argon atmosphere containing hydrogen gas, a nitrogen atmosphere containing hydrogen gas, a hydrogen sulfide atmosphere, etc. Among these, firing in a hydrogen sulfide atmosphere is preferred.

[0069] When the raw material mixture contains a sulfur (S) raw material, it can be calcined under an atmosphere of hydrogen sulfide, carbon disulfide, or an inert gas. When hydrogen sulfide or carbon disulfide is used, these become sulfur compounds during calcination, and have the effect of suppressing decomposition of the product. On the other hand, when the raw material does not contain a sulfur raw material, it is preferable to calcinate under a sulfur-containing atmosphere such as hydrogen sulfide or carbon disulfide.

[0070] Next, the fired product is crushed into powder. Crushing may be performed by either dry or wet method. In the case of wet method, ethanol, water, etc. can be used as a dispersion medium. Crushing may be performed using a known crusher such as a ball mill, stamp mill, jet mill, crusher, and / or paint shaker. If necessary, the crushed product obtained by crushing may be subjected to classification treatment. When classification is performed, the particle diameter of the product is preferably 0.01 μm or more and 150 μm or less, more preferably 1 μm or more and 50 μm or less, from the viewpoint of improving the handleability and luminescence of the obtained phosphor. The particle diameter here refers to the particle diameter (D50) at 50% of cumulative volume by a laser diffraction scattering type particle size distribution measurement method. In this manner, the phosphor powder of this embodiment can be obtained.

[0071] <<3. Phosphor resin composition>> The phosphor resin composition of the present embodiment contains the above-mentioned phosphor powder and a resin. The phosphor resin composition is a phosphor paste that is a precursor of a phosphor. The phosphor is produced by applying or molding the phosphor resin composition.

[0072] As the resin, for example, one or more selected from thermoplastic resin, thermosetting resin, ionizing radiation curable resin, and two-liquid mixed curable resin can be used. Examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; polyacrylic acid resins such as polyacrylic acid or its ester, polymethacrylic acid or its ester; polyvinyl resins such as polystyrene and polyvinyl chloride; cellulose resins such as triacetyl cellulose; and urethane resins such as polyurethane. Examples of thermosetting resins include silicone resins, phenol resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethane resins, and polyimide resins. Examples of ionizing radiation curable resins include acrylic resins, urethane resins, vinyl ester resins, and polyester alkyd resins. These resins can be used not only as polymers but also as oligomers and monomers. Examples of two-liquid mixed curable resins include epoxy resins.

[0073] The amount of phosphor powder contained in the phosphor resin composition is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, per 100 parts by mass of resin, from the viewpoint of easily ensuring absorptance while obtaining sufficient external quantum efficiency, while being 100 parts by mass or less, more preferably 70 parts by mass or less, per 100 parts by mass of resin, from the viewpoint of ensuring suitable moldability (fillability).

[0074] The phosphor resin composition may contain an organic solvent, an additive, and the like. The viscosity of the phosphor resin composition (phosphor paste) can be adjusted by adding an organic solvent. The organic solvent may be any known solvent that dissolves resin. The additive may be an inorganic filler such as glass particles or metal oxide particles, or a flow adjuster made of an organic component.

[0075] The phosphor resin composition is produced by mixing and kneading phosphor powder, resin, and, if necessary, organic solvent and additives. The mixing and kneading may be carried out by known means, such as a three-roll mill, a kneader, a single-axis or double-axis kneader, a revolution-rotation type stirring and degassing device, and / or a planetary mill. The obtained phosphor resin composition is used as a phosphor paste for producing a phosphor.

[0076] <<4. Phosphor>> The phosphor of this embodiment is a molded body of the phosphor resin composition described above. The molded body is a concept including coatings and fillers obtained from the composition. That is, the phosphor is produced by applying, filling or molding the phosphor resin composition (phosphor paste), and further drying and / or curing as necessary. The phosphor has phosphor powder (particles) dispersed in a resin matrix.

[0077] <<5. Light-emitting element>> The light-emitting element of this embodiment includes the above-mentioned phosphor and excitation source. The excitation source has a function of emitting light toward the phosphor to excite the phosphor. As the excitation source, an LED with a central wavelength of 250 nm to 510 nm, particularly a blue LED with a central wavelength of 450 nm to 460 nm, is suitable. As long as the light from the excitation source is incident on the phosphor, the arrangement of the phosphor and the excitation source is not limited. However, it is preferable to arrange the phosphor directly above the excitation source. This allows the phosphor to more efficiently absorb the light emitted from the excitation source and convert the color. For example, when the light-emitting element is applied to a micro LED display, it is preferable to arrange an LED as an excitation source at the bottom and arrange a phosphor above it in each package rib of the display. Note that quantum dots can also be used as a component of the light-emitting element instead of phosphors, but quantum dots often contain environmentally regulated substances. In addition, phosphors are more advantageous because they have poor durability.

[0078] <<6. Light-emitting device>> The light emitting device of this embodiment includes the above-mentioned light emitting element. The light emitting device is not particularly limited as long as it includes a phosphor light emitting element. For example, a display device such as a display and lighting can be used. The display device can include, but is not limited to, a micro LED display and a mini LED display.

[0079] As the light-emitting device of this embodiment, a micro LED display is particularly suitable. In a micro LED display in which the phosphor layer (phosphor) has a small thickness of several tens to several hundreds of μm, it is required to sufficiently absorb the emitted light (excitation light) to obtain an excellent emission color. The light-emitting element of this embodiment has a high absorption rate of the phosphor provided therein and has an excellent emission color. Therefore, it meets the above-mentioned requirements. EXAMPLES

[0080] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[0081] (1) Preparation of phosphor powder [Examples 1 to 8 and Comparative Examples 1 to 3] Barium sulfide (BaS), strontium sulfide (SrS), europium sulfide (EuS), and gallium sulfide (Ga2S3) were prepared and weighed out so that the molar ratios of Eu (Eu / (Ba+Sr+Eu); luminescence center element concentration ratio), Ba (Ba / (Ba+Sr)), and Ga (Ga / (Eu+Ba+Sr)) were as shown in Table 1 below. Next, the weighed materials were mixed with a paint shaker using a zirconia ball with a diameter of 3 mm for 100 minutes to obtain a raw material mixture. Thereafter, the raw material mixture was fired under a hydrogen sulfide (H2S) atmosphere to obtain a fired product. At this time, firing was performed under the conditions (heating rate, firing temperature, and firing time) shown in Table 1 below.

[0082] 50 g of the obtained fired product and 50 g of ethanol were put into a 500 mL alumina pot to obtain a mixed liquid with a solid content concentration of 50 mass %. Next, a wet crushing process was performed using a ball mill to obtain phosphor powder as a crushed product. During the crushing process, 300 g of zirconia balls with a diameter of 7 mm and 400 g of zirconia balls with a diameter of 3 mm were used. The ball rotation speed was 300 rpm, and the treatment time with the ball mill was 4 hours.

[0083] The obtained phosphor powder (crushed material) was dissolved in acid and subjected to composition analysis by ICP-OES, and it was confirmed that the phosphor powder composition was substantially the same as the charged composition.

[0084] (2) Evaluation The phosphor powders obtained in Examples 1 to 8 and Comparative Examples 1 to 3 were evaluated for various properties as follows.

[0085] <Fluorescence spectrum and excitation spectrum> The fluorescence spectrum and excitation spectrum were obtained for the phosphor powders (samples) obtained in the examples and comparative examples as follows. In detail, a spectrofluorometer FP-8500 and an integrating sphere unit ISF-834 (manufactured by JASCO Corporation) were used to perform measurements and analysis according to a solid quantum efficiency calculation program. The spectrofluorometer was corrected using a secondary standard light source and rhodamine B. The fluorescence spectrum and excitation spectrum were obtained under the conditions of a bandwidth of 5 nm on both the excitation side and the fluorescence side, a scanning speed of 500 nm / min, a data acquisition interval of 0.2 nm, and a response of 1 second. When measuring the fluorescence spectrum, the wavelength of the excitation light was fixed at 450 nm, the fluorescence wavelength was scanned, and the wavelength (maximum fluorescence wavelength λmax) that brings about the maximum (maximum) fluorescence intensity on the spectrum was obtained. In addition, when measuring the excitation spectrum, the excitation light wavelength was scanned to obtain a spectrum showing the fluorescence intensity of the maximum fluorescence wavelength λmax.

[0086] Next, in the obtained excitation spectrum, the fluorescence intensity (I 250 ), and the fluorescence intensity (I 450 ), and the fluorescence intensity (I500 ), and the maximum fluorescence intensity (I 330-360 ), and the maximum fluorescence intensity (I 380-420 ) and calculate the fluorescence intensity ratio (I 450 / I 380-420 , I 450 / I 330-360 , I 450 / I 500 and I 380-420 / I 250 ) was calculated.

[0087] <Absorption rate> The phosphor powder (sample) was used as a sample for measuring the absorptivity, and the absorptivity (Abs.) was measured as follows. In detail, a spectrofluorophotometer FP-8500 and an integrating sphere unit ISF-834 (manufactured by JASCO Corporation) were used to perform measurements and analysis according to a solid-state quantum efficiency calculation program. The spectrofluorophotometer was corrected using a secondary standard light source and rhodamine B. The formula for calculating the absorptivity of the phosphor powder (sample) is shown below when the excitation light is 450 nm under the conditions of a bandwidth of 5 nm on both the excitation side and the fluorescence side, a scanning speed of 500 nm / min, a data acquisition interval of 0.2 nm, and a response of 1 second. This formula complies with the description in the instruction manual for the solid-state quantum efficiency calculation program FWSQ-6-17(32) manufactured by JASCO Corporation.

[0088] Let P1(λ) be the standard white board spectrum and P2(λ) be the sample spectrum. The area L1 (hereafter referred to as the area P1(λ)) surrounded by the excitation wavelength range of 433 nm to 472 nm The excitation intensity is expressed as (i) below. The area L2 (hereafter referred to as the area P2(λ)) surrounded by the excitation wavelength range of 433 nm to 472 nm The scattering intensity of the sample is expressed as the scattering intensity (see equation (ii) below).

[0089]

number

[0090] The absorptance (Abs.) is the ratio of the excitation light attenuated by the sample to the incident light, and is calculated according to the following formula (iii):

[0091]

number

[0092] (3) Evaluation results For Examples 1 to 8 and Comparative Examples 1 to 3, the fluorescence intensity ratio (I 450 / I 380-420 , I 450 / I 330-360 , I 450 / I 500 and I 380-420 / I 250 ), and absorptance (Abs.) are shown together with the production conditions of the phosphor powder (Eu amount, heating rate, firing temperature, etc.) The excitation spectra of Examples 1 to 8 and Comparative Examples 1 to 3 are shown in FIGS.

[0093] In Examples 1 to 8, the amount of Eu is large, ranging from 0.08 to 0.30, and the samples were prepared by firing at a relatively high temperature (1100°C). In addition, the samples other than Example 7 were prepared by heating at a relatively low rate (0.3°C / min). In these samples, the fluorescence intensity ratio (I 450 / I 380-420 ) is 0.88 or more, and the fluorescence intensity ratio (I 450 / I 330-360 ) is 0.93 or more, and the fluorescence intensity ratio (I 450 / I 500 ) is 1.4 or more and 2.2 or less, and the fluorescence intensity ratio (I 380-420 / I 250 ) was 2.7 or higher, and the absorption rate was accordingly high at 69% or higher.

[0094] In contrast, Comparative Examples 1 and 2 are samples prepared with a low Eu content of 0.01 to 0.07, and with a high heating rate (5° C. / min). 450 / I 380-420 is low at 0.86 or less, and I 450 / I 330-360is less than or equal to 0.92, and I 450 / I 500 is less than 1.4 or more than 2.2, and I 380-420 / I 250 was below 2.6, and the absorption rate was correspondingly low at below 61%.

[0095] Comparative Example 3 is a sample that contains a large amount of Eu (0.13), but is sintered at a relatively low temperature (850°C). 450 / I 380-420 is low at 0.87, and I 450 / I 330-360 is 0.90, and I 450 / I 500 is low at 1.37, and I 380-420 / I 250 was low at 1.7, and the absorption rate was correspondingly low at 64%.

[0096] From the above results, it is understood that the present embodiment provides a phosphor powder that exhibits high absorptance for blue light.

[0097] [Table 1]

Claims

1. In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is a fluorescence wavelength that provides the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I ３８０－４２０ ) and the fluorescence intensity (I ４５０ ) and the ratio (I ４５０ / I ３８０－４２０ ) is 0.92 or more, The phosphor powder includes a crystal of a base compound and a luminescent center element, the concentration ratio of the luminescent center element being 8.0 mol % or more and 50 mol % or less, the base compound including at least one metal element selected from the group consisting of barium (Ba) and strontium (Sr), gallium (Ga), and sulfur (S); The phosphor powder has a composition expressed by (Bay, Sr1-y)1-xGazS4:Eux (where 0.08?x?0.30, 0.00?y?0.25, and 1.9?z?2.3).

2. In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is a fluorescence wavelength that provides the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I ３３０－３６０ ) and the fluorescence intensity (I ４５０ ) and the ratio (I ４５０ / I ３３０－３６０ 2. The phosphor powder according to claim 1, wherein the value of n is 0.93 or more.

3. In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is a fluorescence wavelength that provides the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), Fluorescence intensity (I ４５０ ) and the fluorescence intensity (I ５００ ) and the ratio (I ４５０ / I ５００ 2. The phosphor powder according to claim 1, wherein the σ is 1.4 or more and 2.2 or less.

4. In the excitation spectrum showing the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein the maximum fluorescence wavelength λmax is a fluorescence wavelength that provides the maximum fluorescence intensity for excitation light having a wavelength of 450 nm), The maximum fluorescence intensity (I ３８０－４２０ ) and the fluorescence intensity (I ２５０ ) and the ratio (I ３８０－４２０ / I ２５０ 2. The phosphor powder according to claim 1, wherein the σ is 2.7 or more.

5. 5. The phosphor powder according to claim 1, having an absorptivity of 65% or more for excitation light having a wavelength of 450 nm.

6. A phosphor resin composition comprising the phosphor powder according to any one of claims 1 to 4 and a resin.

7. A phosphor comprising the phosphor resin composition according to claim 6.

8. A light emitting device comprising the phosphor according to claim 7 and an excitation source.

9. A light emitting device comprising the light emitting element according to claim 8.

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