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

Abstract

Provided are a phosphor powder exhibiting a high absorptivity with respect to blue light, and a phosphor resin composition, a phosphor, a light-emitting element, and a light-emitting device containing the phosphor powder. The fluorescent powder is characterized in that: in an excitation spectrum exhibiting a fluorescence intensity of a maximum fluorescence wavelength [lambda] max (wherein the maximum fluorescence wavelength [lambda] max is a fluorescence wavelength imparting a maximum fluorescence intensity with respect to excitation light having a wavelength of 450 nm), the maximum fluorescence wavelength [lambda] max is a fluorescence wavelength imparting a maximum fluorescence intensity; the ratio (I450 / I380-420) of the fluorescence intensity (I450) corresponding to excitation light having a wavelength of 450 nm to the maximum fluorescence intensity (I380-420) corresponding to excitation light having a wavelength in the range of 380 nm to 420 nm is 0.88 or more.

Description

Technical Field

[0001] This invention relates to phosphor powder, phosphor resin composition, phosphor, light-emitting element, and light-emitting device. Background Technology

[0002] Light-emitting elements that use light-emitting diodes (LEDs) that emit near-ultraviolet or blue light as a light source (excitation source) and incorporate phosphors are widely used in lighting, backlights for portable terminals, and various other light-emitting devices such as displays.

[0003] In this light-emitting device, the phosphor absorbs the light emitted by the LED (emitted light) and emits light of a different wavelength than the absorbed light. Therefore, it is possible to obtain light with a different hue than the LED's emitted light. For example, by combining a blue LED with a green phosphor and / or a red phosphor, it is possible to obtain green light, red light, or white light.

[0004] For example, Patent Document 1 discloses a white light-emitting element comprising a light-emitting diode that emits blue light, a gallium thioate-based green phosphor that emits green light, and an alkaline earth metal sulfide-based red phosphor that emits red light, wherein the green light and the red light are mixed with a portion of the blue light to emit white light (claim 3 of Patent Document 1). Furthermore, it describes the use of the white light-emitting element as a backlight source for lighting, laptops, etc. (

[0002] of Patent Document 1).

[0005] Looking at displays used for other purposes as phosphors, mini-LED and micro-LED displays have garnered significant attention in recent years due to advancements in display technology. In micro-LED displays, the subpixels R (red), G (green), and B (blue) are each composed of independent LEDs. Compared to LCD panels, they offer advantages such as faster response times and lower power consumption, enabling high brightness and high contrast images. Furthermore, compared to OLED displays, they are capable of displaying bright images without image retention caused by degradation.

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

[0007] The development of materials (fluorescent materials) for phosphors used in these applications is also underway. For example, Patent Document 3 discloses a green phosphor characterized by having a maximum emission wavelength between 500 nm and 600 nm, and a half-width of less than 46 nm, as defined by the following formula Sr 1-x Ga2S4: Eu x(where 0.10≤x≤0.20) represents (claim 1 of Patent Document 3). In addition, regarding this green phosphor, it is disclosed that it can produce light with high color purity and can be used as a backlight for display devices and a light source for illumination (

[0008] and

[0052] of Patent Document 3).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 5052507

[0011] Patent Document 2: Japanese Patent Application Publication No. 2018-182282

[0012] Patent Document 3: Japanese Patent Application Publication No. 2020-139056 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] Thus, although LED phosphors and their materials are used for various applications, excellent emission color is generally desired, meaning it is desirable to suppress the mixing of unwanted emission colors. If extraneous colors are mixed in, it is difficult to obtain the desired hue and vivid image when constructing a light-emitting device. To obtain excellent emission color, a narrow emission spectrum (fluorescence spectrum) that does not transmit blue light is important; therefore, phosphors exhibiting high absorptivity (Abs.) for blue light are desirable. Here, absorptivity is the proportion of light absorbed by the phosphor in the illuminated light.

[0015] For example, such as Figure 1 As shown, ideally, the phosphors used in micro LED displays consist of a phosphor layer composed of green phosphors and a phosphor layer composed of red phosphors that absorb and excite all the blue light emitted by the LED, thereby achieving color conversion. Furthermore, the thickness of the phosphor layer is as small as tens to hundreds of μm. Therefore, even with a thin phosphor layer, it is necessary to fully absorb the emitted light (excitation light), making it particularly important to improve the phosphor's absorption rate.

[0016] However, existing fluorescent materials for LEDs are insufficient to meet these requirements.

[0017] The inventors conducted research in view of these prior problems. As a result, they obtained the following insight: for phosphor powders (powdered fluorescent materials), there is a relationship between the fluorescence intensity ratio at a specific excitation wavelength in the excitation spectrum and the absorption rate; by increasing this fluorescence intensity ratio, the absorption rate of blue light can be increased.

[0018] This invention was made based on the understanding that its objective is to provide a phosphor powder exhibiting high absorption rate for blue light. Furthermore, another objective of this invention is to provide a phosphor resin composition comprising the aforementioned phosphor powder, a phosphor, a light-emitting element, and a light-emitting device.

[0019] Solution for solving the problem

[0020] This invention includes the methods described in (1) to (15) below. Furthermore, in this specification, the expression “~” includes the numerical values ​​at both ends. That is, “X~Y” is synonymous with “X or more and Y or less”.

[0021] (1) A phosphor powder, wherein, in an excitation spectrum displaying a fluorescence intensity at a maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is a fluorescence wavelength that imparts maximum fluorescence intensity to excitation light of wavelength 450 nm),

[0022] Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 The ratio of (I) 450 / I 380-420 The value is above 0.88.

[0023] (2) A phosphor powder, wherein, in an excitation spectrum displaying a fluorescence intensity at a maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light of wavelength 450 nm),

[0024] Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 330 nm and below 360 nm. 330-360 The ratio of (I) 450 / I 330-360 The value is above 0.93.

[0025] (3) A phosphor powder, wherein, in an excitation spectrum displaying fluorescence intensity at a maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light at a wavelength of 450 nm),

[0026] Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 500 nm 500 The ratio of (I) 450 / I 500 The value is above 1.4 and below 2.2.

[0027] (4) A phosphor powder, in an excitation spectrum displaying fluorescence intensity at a maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light of wavelength 450 nm),

[0028] The maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 250 nm 250 The ratio of (I) 380-420 / I 250 The value is above 2.7.

[0029] (5) The phosphor powder according to any one of (1) to (4) above, wherein the phosphor powder comprises a crystal of the parent compound and a luminescent center element.

[0030] (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.

[0031] (7) The phosphor powder according to (5) or (6) above, wherein the parent compound comprises a sulfide-based fluorescent material.

[0032] (8) The phosphor powder according to any one of (5) to (7) above, wherein the parent compound comprises at least one metal element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga) and sulfur (S).

[0033] (9) The phosphor powder according to any one of (5) to (8) above, wherein the parent compound has the basic composition of (Ba,Sr)Ga2S4.

[0034] (10) The phosphor powder according to any one of (1) to (9) above has (Ba, Sr) 1-x Ga2S4: Eu x (where 0.08≤x≤0.50) is the composition shown.

[0035] (11) The phosphor powder according to any one of (1) to (10) above has an absorption rate of more than 65% for excitation light with a wavelength of 450 nm.

[0036] (12) A phosphor resin composition comprising phosphor powder and resin of any one of (1) to (11) above.

[0037] (13) A phosphor comprising the phosphor resin composition of (12) above.

[0038] (14) A light-emitting element having a phosphor and an excitation source as described in (13) above.

[0039] (15) A light-emitting device having the light-emitting element of (14) described above.

[0040] The effects of the invention

[0041] According to the present invention, a phosphor powder exhibiting high absorption rate for blue light is provided. Furthermore, according to the present invention, a phosphor resin composition comprising the phosphor powder, a phosphor, a light-emitting element, and a light-emitting device are provided. Attached Figure Description

[0042] Figure 1 This is a diagram used to illustrate phosphors used in micro LED displays.

[0043] Figure 2 The excitation spectra of the phosphor powders in Examples 1-3 are shown.

[0044] Figure 3 The excitation spectra of the phosphor powders in Examples 4-6 are shown.

[0045] Figure 4 The excitation spectra of the phosphor powders in Examples 7 and 8 are shown.

[0046] Figure 5 The excitation spectra of the phosphor powders in Comparative Examples 1 to 3 are shown. Detailed Implementation

[0047] Specific embodiments of the present invention (hereinafter referred to as "this embodiment") will be described below. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without changing the spirit of the present invention.

[0048] <<1. Fluorescent Powder>>

[0049] The phosphor powder of this embodiment comprises any one or more of the first to fourth methods described below.

[0050] <First Method>

[0051] In the first method, the phosphor powder exhibits a fluorescence intensity at the excitation spectrum displaying the maximum fluorescence wavelength λmax, corresponding to the fluorescence intensity (I) of excitation light at a wavelength of 450 nm. 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 The ratio of (I) 450 / I 380-420The fluorescence intensity is 0.88 or higher. Here, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light at a wavelength of 450 nm. That is, in the excitation spectrum displaying the fluorescence intensity at the maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light at a wavelength of 450 nm), the fluorescence intensity (I) under excitation light at a wavelength of 450 nm is... 450 The maximum fluorescence intensity (I) under excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 The ratio of (I) 450 / I 380-420 The value is above 0.88.

[0052] By increasing the fluorescence intensity ratio (I 450 / I 380-420 The absorption rate of blue light increases, thus suppressing the transmission of blue light. This is presumably due to the presence of luminescent central elements (Eu) in the parent crystal. 2+ (etc.) There are multiple energy levels, but by making the energy at 450nm... 7 The proportion of F3's state is higher than that of... 7 F6 7 F5 increases the absorption rate of blue light. Furthermore, the reason for using a fluorescence intensity ratio relative to the excitation light at a wavelength of 450 nm (I...) is... 450 / I 380-420 The index is used because the most commonly used excitation source for LED phosphors, blue LEDs, has an emission wavelength of 450nm.

[0053] Moreover, by increasing the fluorescence intensity ratio (I 450 / I 380-420 This allows for greater design freedom for light-emitting elements. Specifically, in addition to LEDs with an emission wavelength of 450nm, LEDs with an emission wavelength near 460nm are sometimes used as excitation sources for phosphors. This is achieved by increasing the fluorescence intensity ratio (IL). 450 / I 380-420 By using this method, a stable fluorescence intensity relative to the excitation wavelength can be obtained. Therefore, the freedom to choose the excitation wavelength and excitation source is increased. From the perspective of not only improving the absorption rate of blue light but also increasing the design freedom of the light-emitting element, the fluorescence intensity ratio (I0) is improved. 450 / I 380-420 The fluorescence intensity ratio (I) is preferably 0.90 or higher, more preferably 0.91 or higher. It should be noted that the fluorescence intensity ratio (I) is... 450 / I 380-420 The upper limit for fluorescence intensity ratio (I) is 1.00. That is, the fluorescence intensity ratio (I) is... 450 / I 380-420Preferably, the value is 0.88 or higher and 1.00 or lower, more preferably 0.91 or higher and 1.00 or lower.

[0054] Fluorescence intensity ratio (I 450 / I 380-420 The fluorescence spectrum (luminescence spectrum; PL spectrum) can be determined through the following steps. First, analyze the phosphor powder using a fluorescence spectrophotometer to obtain the fluorescence spectrum. The fluorescence spectrum is a spectrum of fluorescence intensity obtained by fixing the excitation wavelength to a specific value and scanning the fluorescence wavelength. By investigating the fluorescence spectrum, it is possible to determine which wavelength emits the most intense fluorescence in the phosphor's emission. Then, from the obtained fluorescence spectrum, determine the wavelength that imparts the maximum (maximum) fluorescence intensity (maximum fluorescence wavelength λmax). In phosphor powders emitting green light (green phosphor powder), λmax is typically in the range of 490 nm to 550 nm (e.g., 535 nm).

[0055] Next, the phosphor powder is analyzed using a fluorescence spectrophotometer to determine the excitation spectrum (PLE spectrum). The excitation spectrum is a spectrum of fluorescence intensity obtained by scanning the wavelength of excitation light incident on the phosphor with the fluorescence wavelength (the wavelength of light emitted from the phosphor) fixed at a specific value. By investigating the excitation spectrum, it is possible to determine which wavelength produces the strongest fluorescence, i.e., the optimal excitation wavelength. In this embodiment, the excitation spectrum is determined by fixing the fluorescence wavelength at the maximum fluorescence wavelength λmax.

[0056] Then, in the obtained excitation spectrum, the maximum fluorescence intensity (I) of the excitation light corresponding to the wavelength range of 380 nm to 420 nm is determined. 380-420 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 450 nm. 450 Here, the maximum fluorescence intensity (I) 380-420 The fluorescence intensity is highest in the range of excitation wavelength above 380 nm and below 420 nm. Additionally, the fluorescence intensity (I) 450 The fluorescence intensity is denoted by I0 at an excitation wavelength of 450 nm. Then, the obtained I0... 380-420 and I 450 Calculate the fluorescence intensity ratio (I 450 / I 380-420 ).

[0057] <Second Method>

[0058] In the second method, the phosphor powder exhibits a fluorescence intensity corresponding to excitation light at a wavelength of 450 nm in an excitation spectrum displaying the fluorescence intensity at the maximum fluorescence wavelength λmax. 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 330 nm and below 360 nm. 330-360The ratio of (I) 450 / I 330-360 The value is 0.93 or higher. Here, the maximum fluorescence wavelength λmax is as described in the first method. Additionally, the maximum fluorescence intensity (I...) 330-360 The maximum fluorescence intensity is achieved within the range of excitation wavelengths above 330 nm and below 360 nm. That is, in the excitation spectrum exhibiting the fluorescence intensity at the maximum fluorescence wavelength λmax (where λmax is the fluorescence wavelength that imparts maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light at a wavelength of 450 nm), the fluorescence intensity at excitation light at a wavelength of 450 nm (I0) is the highest fluorescence intensity. 450 The maximum fluorescence intensity (I) under excitation light in the range of wavelengths above 330 nm and below 360 nm. 330-360 The ratio of (I) 450 / I 330-360 The value is above 0.93.

[0059] By increasing the fluorescence intensity ratio (I 450 / I 330-360 The absorption rate of blue light is further increased. This is presumably due to the presence of luminescent central elements (Eu) in the parent crystal. 2+ Multiple orbitals exist as 5d orbitals in (etc.), especially through their interaction with the maximum fluorescence intensity (I). 330-360 ) of 5d xy 5d x^2-y^2 The presence ratio increases the effect on fluorescence intensity (I) 450 ) of 5d Z^2 The presence of [a certain substance] increases the absorption rate of blue light. From the perspective of increasing absorption rate, the fluorescence intensity ratio (I [a certain substance]) is [a certain percentage]. 450 / I 330-360 More preferably, the fluorescence intensity ratio is 0.95 or higher, and even more preferably 0.96 or higher. Additionally, the fluorescence intensity ratio (I...) 450 / I 330-360 The upper limit of fluorescence intensity ratio (I) is preferably 2.00. That is, the fluorescence intensity ratio (I) 450 / I 330-360 Preferably, the value is 0.93 or higher and 2.00 or lower, more preferably 0.95 or higher and 2.00 or lower, and even more preferably 0.96 or higher and 2.00 or lower.

[0060] <Third Method>

[0061] In the third method, the phosphor powder exhibits a fluorescence intensity at the excitation spectrum displaying the maximum fluorescence wavelength λmax, corresponding to the fluorescence intensity (I) of excitation light at a wavelength of 450 nm. 450 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 500 nm 500 The ratio of (I) 450 / I500 The fluorescence intensity is 1.4 or higher and 2.2 or lower. Here, the maximum fluorescence wavelength λmax is as described in the first embodiment. That is, in the excitation spectrum displaying the fluorescence intensity at an excitation wavelength of 450 nm (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts the maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light at a wavelength of 450 nm), the fluorescence intensity (I) under excitation light at a wavelength of 450 nm is... 450 ) and fluorescence intensity under excitation light at a wavelength of 500 nm (I 500 The ratio of (I) 450 / I 500 The value is above 1.4 and below 2.2.

[0062] By comparing the fluorescence intensity ratio (I 450 / I 500 Within the aforementioned range, the absorption rate 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. That is, it is assumed that if the absorption rate at this wavelength (500 nm) is high, it will reabsorb the light converted by the phosphor, thus reducing the luminescence performance. Therefore, it is speculated that the excitation intensity at 500 nm needs to be moderately lower than 450 nm. From the viewpoint of improving absorption rate, the fluorescence intensity ratio (I... 450 / I 500 More preferably, it is 1.6 or higher and 2.0 or lower.

[0063] <Fourth Method>

[0064] In the fourth method, the phosphor powder exhibits a fluorescence intensity in an excitation spectrum that displays the maximum fluorescence wavelength λmax, corresponding to the maximum fluorescence intensity (I) of the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 250 nm 250 The ratio of (I) 380-420 / I 250 The maximum fluorescence intensity (I) is 2.7 or higher. Here, the maximum fluorescence wavelength λmax is as described in the first embodiment. That is, in the excitation spectrum displaying the maximum fluorescence wavelength λmax (wherein, the maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts the maximum fluorescence intensity in the emission spectrum (fluorescence spectrum) measured with excitation light at a wavelength of 450 nm), the maximum fluorescence intensity (I) under excitation light in the range of 380 nm or higher and 420 nm or lower is considered. 380-420 ) and fluorescence intensity under excitation light at a wavelength of 250 nm (I 250 The ratio of (I) 380-420 / I 250 The value is above 2.7.

[0065] By comparing the fluorescence intensity ratio (I380-420 / I 250 Within the aforementioned range, the absorption rate of blue light is further increased. The reason for this is speculated to be that the 250nm region corresponds to the excitation band of the parent compound, and the luminescent center element (Eu) in the parent compound... 2+ The higher the concentration of (etc.), the lower the probability of the presence of the excited parent compound. From the viewpoint of improving absorbance, the fluorescence intensity ratio (I... 380-420 / I 250 More preferably, the fluorescence intensity ratio is 2.8 or higher, and even more preferably 2.9 or higher. For the fluorescence intensity ratio (I... 380-420 / I 250 There is no upper limit to the fluorescence intensity ratio (IL). However, it is typically below 5.0. That is, the fluorescence intensity ratio (IL) is... 380-420 / I 250 Preferably, the value is 2.7 or higher and 5.0 or lower, more preferably 2.8 or higher and 5.0 or lower, and even more preferably 2.9 or higher and 5.0 or lower.

[0066] The phosphor powder of this embodiment satisfies at least one of the requirements specified in the first to fourth embodiments described above. That is, it may satisfy only one requirement, or it may satisfy any two or more requirements, or it may satisfy all of them. If it satisfies any two or more requirements, it is sufficient to combine and satisfy any two or more requirements in the first to fourth embodiments.

[0067] The phosphor powder of this embodiment is not limited in its material composition as long as it exhibits fluorescent properties. The phosphor powder is composed of fluorescent materials, which typically contain crystals of a parent compound and a luminescent central element (activator). As fluorescent materials, oxide-based, sulfide-based, oxysulfide-based, nitride-based, and oxynitride-based materials are known, and any of them can be used.

[0068] For example, (Y,Gd,Lu)3(Al,Ga)5O can be cited as an oxide-based fluorescent material. 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+ wait.

[0069] As a sulfide-based fluorescent material, (Ba,Sr,Ca)Ga2S4:Eu can be listed as an example. 2+ (Ba, Sr, Ca)Ga2S4: Ce 3+ (Sr, Ca)S: Eu 2+ (Sr, Cd)S: Eu 2+ And ZnS:Cu, etc.

[0070] As an oxygen sulfide-based fluorescent material, (La,Y)₂O₂S:Eu 3+ and La(Ca,Sr)Ga3S6O:Eu 2+ wait.

[0071] Examples of nitride-based fluorescent materials include (Ba,Sr,Ca)₂Si₅N₈:Eu 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+ wait.

[0072] Examples of oxynitride-based fluorescent materials include Eu-containing α-type silanes, Eu-containing β-type silanes, and Ba9Sc3Si6O. 21 N3: Eu 2+ Ba3Si6O 12 N2: Eu 2+ BaSi2O2N2:Eu 2+ and (Ba, Sr, Ca)AlSi(ON)3:Eu 2+ wait.

[0073] Other fluorescent materials, such as Sr, can be cited as examples. 10 (PO4)6C 12 Eu2+ and K2(Si,Ge,Ti)F6:Mn 4+ wait.

[0074] According to a preferred embodiment, as listed in the above-described sulfide-based fluorescent materials, the phosphor powder comprises a parent compound and a luminescent center element. The parent compound comprises at least one metallic element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), as well as gallium (Ga) and sulfur (S). More preferably, the parent compound has the basic composition (Ba,Sr)Ga₂S₄. Preferably, the luminescent center element comprises at least one element selected from the group consisting of europium (Eu), cerium (Ce), manganese (Mn), and samarium (Sm). From the viewpoint of improving the internal quantum efficiency (IQE) under excitation of blue light generated by the LED, the luminescent center element preferably comprises Eu, more preferably a divalent ion (Eu) comprising Eu. 2+ Further optimization is to include only Eu. 2+ .

[0075] Provided that the phosphor powder meets the fluorescence intensity ratio requirements specified in the first to fourth methods described above, the content of the luminescent central element in the phosphor powder is not limited. However, from the viewpoint of more reliably and easily meeting the above requirements, it is preferable to solid-dissolve the luminescent central element in the phosphor powder at a high concentration. By solid-dissolving the luminescent central element at a high concentration, a high fluorescence intensity ratio (Ifluorescence) can be achieved. 450 / I 380-420 (etc.) and absorption rate. 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 refers to the ratio (XA / (XM+XA)) of the molar amount of the luminescent center element (XA) relative to the sum of the molar amounts of the parent compound (XM) and the molar amounts of the luminescent center element (XA) contained in the phosphor powder. The higher the concentration ratio of the luminescent center element, the higher the absorption rate. 450 / I 380-420 The higher the concentration ratio, the higher the absorption rate of blue light. From the viewpoint of improving absorption rate, the concentration ratio is preferably 12 mol% or more, more preferably 13 mol% or more. On the other hand, if the concentration ratio is too high, the luminescent center element cannot be completely dissolved in the parent compound, sometimes resulting in the formation of heterogeneous phases. The formation of heterogeneous phases may cause problems such as reduced luminescence intensity. From the viewpoint of suppressing the formation of heterogeneous phases, the concentration ratio is preferably 45 mol% or less, more preferably 40 mol% or less. From the viewpoint of suppressing the formation of heterogeneous phases and improving absorption rate, the concentration ratio is preferably 12 mol% or more and 45 mol% or less, more preferably 13 mol% or more and 40 mol% or less.

[0076] According to a preferred embodiment, the phosphor powder has (Ba, Sr)1-x Ga2S4: Eu x The composition shown is (wherein 0.08 ≤ x ≤ 0.50). This phosphor powder contains a thiogallium salt compound as the parent compound and europium (Eu) as the luminescent center element, exhibiting green luminescence upon excitation with light in the near-ultraviolet to blue region (approximately 300 nm to 510 nm). Furthermore, due to the high concentration of the luminescent center element (Eu), it exhibits high absorption for blue light. From the viewpoint of improving absorption, the Eu content x is preferably 0.12 or more, more preferably 0.13 or more. From the viewpoint of suppressing heterogeneous phase formation, x is preferably 0.45 or less, more preferably 0.40 or less. From the viewpoint of suppressing heterogeneous phase formation and improving absorption, the Eu content x is preferably 0.12 or more and 0.45 or less, more preferably 0.13 or more and 0.40 or less.

[0077] According to a more preferred embodiment, the phosphor powder has a composition of (Ba y Sr 1-y ) 1-x Ga z S4: Eu x The composition is represented by (where 0.08≤x≤0.50, 0.00≤y≤1.00, 1.5≤z≤2.5). Because this phosphor powder contains a high concentration of the luminescent center element (Eu), it exhibits high absorption for blue light. From the viewpoint of improving absorption, the Eu content x is preferably 0.12 or more, more preferably 0.13 or more. From the viewpoint of suppressing heterogeneous phase formation, x is preferably 0.45 or less, more preferably 0.40 or less. From the viewpoint of improving absorption, the Ba content y is preferably 0.50 or less, more preferably 0.30 or less. From the viewpoint of suppressing heterogeneous phase formation, the Ga content z is preferably 1.7 or more and 2.3 or less.

[0078] The phosphor powder may or may not have a coating. A coating improves durability, such as moisture resistance. From the viewpoint of improving durability and maintaining the good luminescence properties of the phosphor, the coating is preferably composed of one or more inorganic compounds selected from silicon dioxide (SiO2), zinc oxide (ZnO), aluminum oxide (Al2O3), titanium oxide (TiO2), and / or boron (B)-containing oxides, barium sulfate (BaSO4), and other metal sulfates.

[0079] Phosphor powders may also contain components other than fluorescent materials. Examples of such components include fluxing agents and sintering aids added during the synthesis of phosphor powders.

[0080] The phosphor powder of this embodiment has a higher fluorescence intensity ratio than any one of the ratios specified in the first to fourth embodiments described above, thus resulting in a high absorption rate of blue light. As a result, the emission spectrum (fluorescence spectrum) is narrow, exhibiting excellent emission color. From the viewpoint of obtaining a more superior emission color, a higher absorption rate for excitation light at a wavelength of 450 nm is preferred. Specifically, the absorption rate is preferably 65% ​​or higher, more preferably 69% or higher, and even more preferably 75% or higher. There is no upper limit to the absorption rate; it can be 100% or lower. However, in some applications such as lighting and mini LED displays, it is sometimes not necessary to increase the absorption rate to 100%. In such cases, the absorption rate can be 95% or lower. The absorption rate is preferably 65% ​​or higher and 100% or lower, more preferably 69% or higher and 100% or lower, and even more preferably 75% or higher and 95% or lower.

[0081] <<2. Manufacturing Method of Phosphor Powder>>

[0082] The phosphor powder of this embodiment satisfies the above-mentioned requirements, and its manufacturing method is not limited. However, it is preferable to manufacture it by dissolving the luminescent center element in the parent compound at a high concentration and increasing the crystallinity of the parent compound to further reduce strain. Specifically, a preferred 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). Furthermore, from the viewpoint of easily achieving improved solid solution of the luminescent center element and increased crystallinity of the parent compound, it is preferable to reduce (slow down) the heating rate during firing the raw material mixture and increase the firing temperature to a certain extent. The phosphor powder has a composition of (Ba, Sr)... 1-x Ga2S4: Eu x (where 0.08≤x≤0.50) represents the composition case, the following describes the details of the preferred manufacturing method.

[0083] <Raw Material Mixing Process>

[0084] In the raw material mixing process, raw materials are mixed to prepare a raw material mixture. The phosphor powder has a composition of (Ba, Sr) 1-x Ga2S4: Eu x As indicated, barium (Ba), strontium (Sr), gallium (Ga), europium (Eu), and sulfur (S) as needed are weighed and mixed. The mixing ratio of the raw materials is expressed as (Ba, Sr) to form the composition of the final phosphor powder. 1-x Ga2S4: Eu xThe adjustment can be made in the manner of 0.08≤x≤0.50. Furthermore, the raw material may contain only one of the constituent elements (constituent elements) that constitute the phosphor powder, or it may contain a combination of multiple constituent elements. When using a solid component as the sulfur raw material, the sulfur raw material may be mixed in. When using a gaseous component as the sulfur raw material, the sulfur raw material may not be mixed in.

[0085] Examples of barium and strontium raw materials include, for example, oxides, sulfides, complex oxides, and / or carbonates of each element. Examples of gallium raw materials include oxides (Ga₂O₃, GaO). Examples of sulfur raw materials include strontium sulfide (SrS), barium sulfide (BaS), sulfur (S), silicon sulfide (SiS₂), cerium sulfide (Ce₂S₃), and / or hydrogen sulfide (H₂S) gas. Examples of europium raw materials include europium fluoride (EuF₃), europium oxide (Eu₂O₃), and / or europium chloride (EuCl₃).

[0086] To adjust the emission wavelength of phosphor powder and improve external quantum efficiency (EQE), rare earth elements such as praseodymium (Pr) and samarium (Sm) can be added to the raw material. Additionally, to improve excitation efficiency, at least one rare earth element selected from scandium (Sc), lanthanum (La), gadolinium (Gd), and lutetium (Lu) can be added as a sensitizer to the raw material. However, the amount of each sensitizer added is preferably 5 mol% or less relative to strontium (Sr). By keeping the content of these elements below 5 mol%, excessive heterogeneous precipitation can be prevented, thus preventing a significant decrease in brightness. Furthermore, alkali metal elements and silver ions (Ag) can also be added. + Monovalent cations such as chloride (Cl), fluorine (F), and iodine (I) are added to the raw materials as charge compensators. From the perspective of charge compensation effect and brightness, the amount added is preferably about the same as the content of aluminum group elements and rare earth elements.

[0087] There are no limitations on the method of mixing the raw materials. It can be carried out using either dry or wet methods. In the case of dry mixing, for example, zirconia balls are used as a medium, and the mixture is prepared using a mixer such as a paint mixer or ball mill. The mixture is then dried as needed to produce the raw material mixture. In the case of wet mixing, for example, a solvent such as water is added to the raw materials to form a suspension. Zirconia balls are used as a medium, and the mixture is prepared using a mixer such as a paint mixer or ball mill. The solvent is then removed from the suspension using a separation medium such as a sieve, and further dried by methods such as reduced pressure drying or vacuum drying.

[0088] Next, the obtained raw material mixture is fired to produce a fired product. If necessary, the raw material mixture may be pulverized, graded, and / or dried before firing, or this may be omitted.

[0089] From the element that promotes luminescence center (Eu) 2+ From the viewpoint of solid solution of the luminescent center element and improving the crystallinity of the parent compound, it is preferable to reduce the heating rate during firing the raw material mixture and to raise the firing temperature to a certain level. If the heating rate is too high or the firing temperature is too low, solid solution of the luminescent center element will not occur, and heterogeneous phases may remain in the final phosphor powder. In addition, the crystallinity of the parent compound will decrease, and residual strain may remain. On the other hand, if the heating rate is too low or the firing temperature is too high, the process time will increase, and productivity may decrease. In addition, the volatilization of constituent elements in the raw material mixture may cause compositional deviations in 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 holding time is preferably 24 hours or more and 168 hours or less.

[0090] The firing atmosphere can be an inert gas or a reducing gas. Examples include argon atmosphere, nitrogen atmosphere, sulfur atmosphere, argon atmosphere containing hydrogen, nitrogen atmosphere containing hydrogen, and hydrogen sulfide atmosphere. Among these, firing in a hydrogen sulfide atmosphere is preferred.

[0091] When the raw material mixture contains sulfur (S), calcination can be carried out in an atmosphere of hydrogen sulfide, carbon disulfide, or an inert gas. When using hydrogen sulfide or carbon disulfide, they form sulfur compounds during calcination, which inhibits the decomposition of the product. On the other hand, when the raw material does not contain sulfur, calcination is preferably carried out in a sulfur-containing atmosphere such as hydrogen sulfide or carbon disulfide.

[0092] Next, the calcined material is crushed and pulverized. Crushing can be carried out using either dry or wet methods. In the case of wet crushing, ethanol, water, or the like can be used as the dispersion medium. Crushing can be performed using known crushers such as ball mills, pulverizers, spray mills, mortar mixers, and / or paint mixers. If necessary, the crushed material obtained by crushing can be graded. When grading is performed, from the viewpoint of improving the operability and luminescence of the obtained phosphor, the particle size 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. It should be noted that the particle size referred to here is the particle size at 50% of the cumulative volume (D50) based on the laser diffraction scattering particle size distribution method. In this way, the phosphor powder of this embodiment can be obtained.

[0093] <<3. Fluorescent Resin Composition>>

[0094] The phosphor resin composition of this embodiment comprises the above-described phosphor powder and resin. The phosphor resin composition is a phosphor paste that serves as a precursor of a phosphor. A phosphor is produced by coating or molding the phosphor resin composition.

[0095] As resins, one or more selected from thermoplastic resins, thermosetting resins, ionizing radiation-curing resins, and two-component mixed-curing resins 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 esters and polymethacrylic acid or its esters; polyvinyl resins such as polystyrene and polyvinyl chloride; cellulose resins such as cellulose triacetate; and urethane resins such as polyurethane. Examples of thermosetting resins include silicone resins, phenolic resins, epoxy resins, melamine resins, urea-formaldehyde resins, unsaturated polyester resins, alkyd resins, polyurethane resins, and polyimide resins. Examples of ionizing radiation-curing resins include acrylic resins, urethane resins, vinyl ester resins, and polyester alkyd resins. These resins can use not only polymers but also oligomers and monomers. Examples of two-component mixed-curing resins include epoxy resins.

[0096] From the viewpoint of obtaining sufficient external quantum efficiency and easily ensuring absorption rate, 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, relative to 100 parts by mass of the resin. On the other hand, from the viewpoint of ensuring suitable formability (filling properties), it is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, relative to 100 parts by mass of the resin.

[0097] Phosphor resin compositions may include organic solvents, additives, etc. By adding organic solvents, the viscosity of the phosphor resin composition (phosphor paste) can be adjusted. Known organic solvents for dissolving resins can be used. As additives, flow modifiers composed of inorganic fillers such as glass particles and metal oxide particles, and / or organic components, can be used.

[0098] The phosphor resin composition is manufactured by mixing and kneading phosphor powder, resin, and, as needed, organic solvents and additives. Mixing and kneading can be performed using known methods such as three-roll mills, kneaders, single-screw or twin-screw mixers, rotary-rotating degassing devices, and / or planetary mills. The resulting phosphor resin composition is used as a phosphor paste for the production of phosphors.

[0099] <<4. Fluorescent Agents>>

[0100] The phosphor in this embodiment is a molded body of the phosphor resin composition described above. A molded body is a concept encompassing a coating and filler obtained from the composition. That is, a phosphor is produced by coating, filling, or molding a phosphor resin composition (phosphor paste), and then drying and / or curing it as needed. The phosphor comprises phosphor powder (particles) dispersed in a resin serving as a matrix.

[0101] <<5. Light-emitting elements>>

[0102] The light-emitting element of this embodiment includes the phosphor and excitation source described above. The excitation source has the function of emitting light to the phosphor to excite it. As the excitation source, an LED with a center wavelength of 250 nm or more and 510 nm or less is preferred, and a blue LED with a center wavelength of 450 nm or more and 460 nm or less is particularly preferred. The arrangement of the phosphor and the excitation source is not limited as long as light from the excitation source is incident on the phosphor. However, it is preferable to arrange the phosphor directly above the excitation source. This allows the phosphor to absorb the light emitted from the excitation source more efficiently and perform color conversion. For example, when the light-emitting element is applied to a micro LED display, it is preferable to arrange the LED as the excitation source at the bottom and the phosphor at the top of each package rib of the display. In addition, quantum dots, which are not phosphors, can also be used as components of the light-emitting element, but most quantum dots contain environmentally limited materials. Furthermore, phosphors are advantageous due to their lack of durability.

[0103] <<6. Light-emitting device>>

[0104] The light-emitting device of this embodiment includes the light-emitting element described above. There is no particular limitation as long as the light-emitting device includes a phosphor light-emitting element. Examples include display devices such as monitors and lighting equipment. Examples of display devices include micro LED displays and mini LED displays, but are not limited to these.

[0105] As the light-emitting device of this embodiment, a micro-LED display is particularly preferred. For micro-LED displays with a phosphor layer (phosphor) thickness as small as tens to hundreds of μm, it is required to fully absorb emitted light (excitation light) to obtain excellent emission color. The light-emitting element of this embodiment possesses a phosphor with high absorptivity and excellent emission color. Therefore, it meets the above requirements.

[0106] Example

[0107] The invention is illustrated in more detail using the following embodiments. However, the invention is not limited to the following embodiments.

[0108] (1) Preparation of phosphor powder

[0109] [Examples 1-8 and Comparative Examples 1-3]

[0110] Barium sulfide (BaS), strontium sulfide (SrS), europium sulfide (EuS), and gallium sulfide (Ga₂S₃) were prepared and weighed in molar ratios as shown in Table 1 below, with the amounts of Eu (Eu / (Ba+Sr+Eu); luminescent center element concentration ratio), Ba (Ba / (Ba+Sr)), and Ga (Ga / (Eu+Ba+Sr)). The resulting mixtures were then mixed in a paint mixer for 100 minutes using zirconia balls with a diameter of 3 mm to obtain a raw material mixture. The raw material mixture was then calcined in a hydrogen sulfide (H₂S) atmosphere to obtain a calcined product. Calcination was carried out under the conditions shown in Table 1 below (heating rate, calcination temperature, and calcination time).

[0111] 50g of the calcined product and 50g of ethanol were added to a 500mL alumina container to obtain a mixture with a solid content of 50% by mass. Next, wet grinding was performed using a ball mill to obtain phosphor powder as the ground product. For the grinding process, 300g of 7mm diameter zirconia balls and 400g of 3mm diameter zirconia balls were used. The ball rotation speed was 300rpm, and the processing time using the ball mill was 4 hours.

[0112] The obtained phosphor powder (crushed material) was dissolved in acid, and the composition was analyzed by ICP-OES. The results confirmed that the composition of the phosphor powder was approximately the same as that of the feed.

[0113] (2) Evaluation

[0114] The phosphor powders obtained in Examples 1-8 and Comparative Examples 1-3 were evaluated for various properties as follows.

[0115] <Fluorescence Spectroscopy and Excitation Spectroscopy>

[0116] For the phosphor powders (samples) obtained in the examples and comparative examples, the fluorescence and excitation spectra were determined as follows. Specifically, a fluorescence spectrophotometer FP-8500 and an integrating sphere unit ISF-834 (manufactured by Nippon Spectrophotometer Co., Ltd.) were used, and measurements and analysis were performed according to a solid-state quantum efficiency calculation procedure. The fluorescence spectrophotometer was calibrated using a substandard light source and Rhodamine B. The fluorescence and excitation spectra were determined under the following conditions: a bandwidth of 5 nm on both the excitation and fluorescence sides, a scan speed of 500 nm / min, a data acquisition interval of 0.2 nm, and a response time of 1 second. During fluorescence spectroscopy determination, the excitation wavelength was fixed at 450 nm, and the fluorescence wavelength was scanned to determine the wavelength at which the maximum fluorescence intensity (maximum fluorescence wavelength λmax) is achieved. Similarly, during excitation spectroscopy determination, the excitation wavelength was scanned to determine the spectrum displaying the fluorescence intensity at the maximum fluorescence wavelength λmax.

[0117] Next, in the obtained excitation spectrum, the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 250 nm was calculated. 250 ), the fluorescence intensity corresponding to the excitation light at a wavelength of 450 nm (I 450 ), corresponding to the fluorescence intensity (I) of excitation light at a wavelength of 500 nm 500 ), corresponding to the maximum fluorescence intensity (I) of excitation light in the range of wavelengths above 330 nm and below 360 nm. 330-360 ), and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 ), 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 ).

[0118] <Absorption Rate>

[0119] The absorbance of the phosphor powder (sample) was measured as follows. Specifically, the absorbance was measured and analyzed using a fluorescence spectrophotometer FP-8500 and an integrating sphere unit ISF-834 (manufactured by Nippon Spectrophotometer Co., Ltd.) according to the solid-state quantum efficiency calculation procedure. The fluorescence spectrophotometer was calibrated using a substandard light source and Rhodamine B. The following is a formula for calculating the absorbance of the phosphor powder (sample) with an excitation light of 450 nm under the following conditions: a bandwidth of 5 nm on both the excitation and fluorescence sides, a scan rate of 500 nm / min, a data acquisition interval of 0.2 nm, and a response of 1 second. This formula is based on the instruction manual of the solid-state quantum efficiency calculation procedure FWSQ-6-17(32) manufactured by Nippon Spectrophotometer Co., Ltd.

[0120] P1(λ) was used as the standard white plate spectrum, and P2(λ) was used as the sample spectrum.

[0121] The area L1 (refer to equation (i) below) enclosed by the spectrum P1(λ) in the range of excitation wavelengths from 433 nm to 472 nm is taken as the excitation intensity.

[0122] The area L2 (refer to equation (ii) below) enclosed by the spectrum P2(λ) in the range of excitation wavelengths from 433 nm to 472 nm is taken as the scattering intensity of the sample.

[0123]

[0124] Absorption rate (Abs.) is the ratio of the reduction in excitation light caused by the sample to the incident light, calculated according to the following formula (iii).

[0125]

[0126] (3) Evaluation Results

[0127] For Examples 1-8 and Comparative Examples 1-3, the fluorescence intensity ratio (I 450 / I 380-420 I 450 / I 330-360 I 450 / I 500 and I 380-420 / I 250 The absorbance (Abs.) and the manufacturing conditions of the phosphor powder (Eu amount, heating rate, firing temperature, etc.) are shown together. In addition, the excitation spectra of Examples 1-8 and Comparative Examples 1-3 are shown. Figures 2-5 .

[0128] Examples 1-8 are samples prepared by firing at a relatively high temperature (1100°C) with an Eu content of 0.08 or more and 0.30 or less. In addition, except for Example 7, the samples were prepared with a relatively low heating rate (0.3°C / min). In these samples, the fluorescence intensity ratio (I... 450 / I 380-420 The fluorescence intensity ratio (I) is above 0.88. 450 / I 330-360 The fluorescence intensity ratio (I) is above 0.93. 450 / I 500 The fluorescence intensity ratio (I) is above 1.4 and below 2.2. 380-420 / I 250 The concentration is above 2.7, therefore the corresponding absorption rate is as high as 69% or more.

[0129] In contrast, Comparative Examples 1 and 2 were samples prepared with Eu levels as low as 0.01 to 0.07 and with increased heating rates (5°C / min). In these samples, I... 450 / I 380-420 As low as below 0.86, I 450 / I 330-360 Below 0.92, I 450 / I 500 Less than 1.4 or more than 2.2, I 380-420 / I 250 The value is below 2.6, and therefore the absorption rate is correspondingly low, below 61%.

[0130] Comparative Example 3 is a sample prepared with an Eu content as high as 0.13, but fired at a lower temperature (850°C). In this sample, I 450 / I 380-420 As low as 0.87, I 450 / I 330-360 It is 0.90, I 450 / I 500 As low as 1.37, I 380-420 / I 250 As low as 1.7. Therefore, the corresponding absorption rate is as low as 64%.

[0131] As can be seen from the above results, according to this embodiment, a phosphor powder exhibiting high absorption rate for blue light can be provided.

[0132] [Table 1]

[0133]

Claims

1. A phosphor powder, wherein, In the excitation spectrum that displays the fluorescence intensity at the maximum fluorescence wavelength λmax, Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 The ratio of (I) 450 / I 380-420 The value is above 0.

88. The maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light with a wavelength of 450 nm.

2. A phosphor powder, wherein, In the excitation spectrum that displays the fluorescence intensity at the maximum fluorescence wavelength λmax, Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 330 nm and below 360 nm. 330-360 The ratio of (I) 450 / I 330-360 The value is above 0.

93. The maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light with a wavelength of 450 nm.

3. A phosphor powder, wherein, In the excitation spectrum that displays the fluorescence intensity at the maximum fluorescence wavelength λmax, Fluorescence intensity (I) corresponding to excitation light at a wavelength of 450 nm 450 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 500 nm 500 The ratio of (I) 450 / I 500 () is above 1.4 and below 2.2 The maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light with a wavelength of 450 nm.

4. A phosphor powder, wherein, In the excitation spectrum that displays the fluorescence intensity at the maximum fluorescence wavelength λmax, The maximum fluorescence intensity (I) corresponding to the excitation light in the range of wavelengths above 380 nm and below 420 nm. 380-420 ) and the fluorescence intensity (I) corresponding to the excitation light at a wavelength of 250 nm 250 The ratio of (I) 380-420 / I 250 The value is above 2.

7. The maximum fluorescence wavelength λmax is the fluorescence wavelength that imparts maximum fluorescence intensity to excitation light with a wavelength of 450 nm.

5. The phosphor powder according to any one of claims 1 to 4, wherein, The phosphor powder contains crystals of the parent compound and a luminescent center element.

6. The phosphor powder according to claim 5, wherein, The concentration ratio of the luminescent center element is above 8.0 mol% and below 50 mol%.

7. The phosphor powder according to claim 5, wherein, The parent compound contains a sulfide-based fluorescent material.

8. The phosphor powder according to claim 5, wherein, The parent compound contains at least one metallic element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), gallium (Ga), and sulfur (S).

9. The phosphor powder according to claim 5, wherein, The parent compound has the basic composition of (Ba,Sr)Ga2S4.

10. The phosphor powder according to any one of claims 1 to 4, wherein it comprises (Ba, Sr) 1-x Ga2S4: Eu x The composition of the representation, in which, 0.08≤x≤0.50。 11. The phosphor powder according to any one of claims 1 to 4, wherein the absorption rate of excitation light with a wavelength of 450 nm is 65% or more.

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

13. A phosphor comprising the phosphor resin composition of claim 12.

14. A light-emitting element comprising the phosphor and excitation source as described in claim 13.

15. A light-emitting device comprising the light-emitting element as described in claim 14.

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