Halide phosphor and light-emitting device

Abstract

To provide a halide phosphor having an emission wavelength band of yellow-red emission and capable of improving internal quantum yield, and a light-emitting device including the same.SOLUTION: A halide phosphor consists of a compound represented by the following chemical formula (1): A2BX6-αX'α. (In formula (1): A is at least one selected from the group consisting of Cs, Rb, K, Na, and Li; B is at least one selected from the group consisting of Hf, Zr, and Ti; and X and X' are each at least one selected from the group consisting of Cl, Br, and I.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a halide phosphor and a light-emitting device including the same. [Background technology]

[0002] White LEDs are currently widely used because they have longer lifespans and lower power consumption than conventional fluorescent lamps. White LEDs generally consist of a blue LED (InGAN) and a yellow phosphor called Ce:Y3Al5O 12 This is because the Ce:YAG emits yellow light when part of the blue light from the blue LED is used, and by combining these two, it can emit pseudo-white light, making it usable as lighting.

[0003] However, the Ce:YAG emission spectrum lacks a red component in the 600-700 nm range, resulting in poor color rendering, an index of natural light reproduction. To address this issue, yellow-red phosphors using rare earth elements such as Eu as the luminescent center have been developed in recent years (see, for example, Non-Patent Document 1). However, the uneven distribution and scarcity of rare earth elements such as Ce and Eu have become a concern. Currently, 70% of the world's rare earth oxide production is concentrated in a single country, and Japan relies almost entirely on imports for its rare earth elements. Therefore, there are concerns about supply shortages and price hikes due to import restrictions, etc. Therefore, the development of yellow-red phosphors that do not use rare earth elements (especially Eu) is important from both an environmental and economic perspective.

[0004] In recent years, halide phosphors with the A2BX6 structure (A = Cs, Rb, B = Ti, Zr, Hf, X = F, Cl, Br, I) that exhibit self-luminescence without the use of additives such as rare earth elements have been attracting attention. The A2BX6 system has an octahedral structure [BX6] in its crystal structure. 2-They exhibit charge transfer transition luminescence or self-trapped exciton luminescence due to the octahedral structure [BX6] in the crystal structure. In particular, Cs2HfCl6 and Cs2ZrCl6 are characterized by their high luminous efficiency without the use of additives, as well as their high atmospheric stability. However, their emission wavelengths are in the ultraviolet-blue range of 300nm to 550nm in both cases, which does not meet the wavelength range required above. As mentioned above, the A2BX6 system has an octahedral structure [BX6] in the crystal structure. 2- The emission wavelength changes due to [BX6] 2- Structural control, i.e., substitution of each A, B, and X site, is effective. In fact, Non-Patent Document 2 reports that when all Cs sites of Cs2HfCl6 are substituted with Rb, the emission wavelength is lengthened by 20 nm in Rb2HfCl6. On the other hand, the emission characteristics when the A site is substituted with K, Rb, Na, or Li, which have smaller atomic numbers than Rb, are unknown.

[0005] In addition, partial substitution of the X site is also effective in shifting the emission wavelength to a longer wavelength. Non-Patent Document 3 reveals that substituting some of the Cl sites of Cs2HfCl6 with Br lengthens the emission wavelength by approximately 150 nm. However, the emission wavelength is approximately 500 nm, which is insufficient for the required yellow-red emission, and the change in emission wavelength when some of the Cl sites are substituted with I, which has a larger ionic radius than Br, has not been fully verified.

[0006] Furthermore, an important characteristic of phosphors is the internal quantum yield. The internal quantum yield indicates the ratio of the number of photons absorbed by a phosphor to the number of photons emitted as fluorescence, and is an index of how efficiently the phosphor emits light. It has been reported that in materials that exhibit self-trapped exciton emission, partial substitution of elements with other elements causes lattice distortion, improving the quantum yield (see Non-Patent Documents 4 to 6). Therefore, it is expected that the structural distortion caused by the substitution of a small amount of iodine will also contribute to the luminous efficiency. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] J.Lakde,et al.,A review,”J.Phys.Conf.Ser.,vol.1913,no.1,2021. [Non-Patent Document 2] K.Saeki,et.al.,Jpn.J.Appl.Phys.,vol.55,no.11,pp.2-4,2016. [Non-Patent Document 3] S.Kodama,et al.,Opt.Mater.,vol.106,p.109942,Aug.2020. [Non-Patent Document 4] Y.Hu,et al.,J.Phys.Chem.Lett.,vol.13,no.46,pp.10786-10792,Nov.2022. [Non-Patent Document 5] Z.Lin,et al.,J.Mater.Chem.,vol.11,no.17,pp.5680-5687,2023. [Non-Patent Document 6] J.H.Han,et al.,Chem.Eng.J.,vol.450,p.138325,Dec.2022. [Non-Patent Document 7] L.Zi,et al.,J.Mater.Chem.,vol.11,no.7,pp.2695-2702,Feb.2023. [Non-Patent Document 8] K.Wang et al.,Nat.Commun.,vol.12,no.1,2021. [Non-Patent Document 9] H. Kwak et al., Energy Storage Materials, vol. 37, no. January, pp. 47-54, 2021. [Non-Patent Document 10] K.Saeki et al.,Jpn.J.Appl.Phys.,vol.55,no.11,pp.2-4,2016. [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] As mentioned above, self-luminescent halide phosphors with the A2BX6 structure are highly stable in the atmosphere and emit light with high efficiency, even without the use of rare earth elements. However, as exemplified by Cs2ZrCl6, reports of their emission wavelengths have focused on the ultraviolet-blue range, which does not meet the required yellow-red emission wavelength range. Furthermore, the changes in emission wavelength and quantum yield due to substitution of each element site are unclear.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a halide phosphor that has an emission wavelength band of yellow-red light and is capable of improving internal quantum yield, and a light-emitting device including the same. [Means for solving the problem]

[0010] The present invention has the following aspects. [1] A halide phosphor consisting of a compound represented by the following chemical formula (1): A2BX 6-α X' α (1) (In formula (1), A is at least one selected from the group consisting of Cs, Rb, K, Na, and Li, B is at least one selected from the group consisting of Hf, Zr, and Ti, and X and X' are at least one selected from the group consisting of Cl, Br, and I.) [2] The halide phosphor according to [1], wherein in the chemical formula (1), 0<α≦3. [3] The halide phosphor according to [1], wherein X is Cl and X' is I in the chemical formula (1). [4] The halide phosphor according to [1], wherein, in the chemical formula (1), A is Li, B is Zr, X is Cl, X' is I, and 0<α≦3. [5] The halide phosphor according to [1], wherein in the chemical formula (1), A is Na, B is Zr, X is Cl, X' is I, and 0<α≦3. [6] The halide phosphor according to [1], wherein, in the chemical formula (1), A is Cs, B is Zr, X is Cl, X' is I, and 0<α≦3. [7] A light-emitting element and a sealing member that seals the light-emitting element, The light emitting device, wherein the sealing member contains the halide phosphor according to any one of [1] to [6]. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a halide phosphor that has an emission wavelength band of yellow to red light and that can improve the internal quantum efficiency, and a light emitting device including the same. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a light-emitting device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing the results of analysis of the crystal structure of the phosphor of Example 1-3 by X-ray diffraction. [Figure 3] FIG. 2 is a diagram showing the results of measuring the emission spectrum of the phosphor of Example 1 when the excitation wavelength is changed. [Figure 4] FIG. 10 is a diagram showing the results of measuring the emission spectrum of the phosphor of Example 2 when the excitation wavelength is changed. [Figure 5] FIG. 10 is a diagram showing the results of measuring the emission spectrum of the phosphor of Example 3 when the excitation wavelength is changed. [Figure 6] FIG. 10 is a diagram showing the results of measuring the blank spectrum and the emission spectrum of Cs2ZrCl5.8I0.2 at an excitation wavelength of 375 nm in Example 3, and calculating the internal quantum yield. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of a halide phosphor and a light emitting device including the same according to the present invention will be described. It should be noted that the present embodiment is specifically described to allow a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0014] [Halide phosphors] A halide phosphor according to one embodiment of the present invention comprises a compound represented by the following chemical formula (1). A2BX 6-α X' α (1) (In formula (1), A is at least one selected from the group consisting of Cs, Rb, K, Na, and Li, B is at least one selected from the group consisting of Hf, Zr, and Ti, and X and X' are at least one selected from the group consisting of Cl, Br, and I.)

[0015] In the above chemical formula (1), 0≦α≦6, preferably 0<α≦3, and more preferably 0.2≦α≦1.0. When α is greater than the lower limit, the emission wavelength shifts to the long wavelength side, resulting in yellow to red emission. When α is equal to or less than the upper limit, a high internal quantum yield is exhibited. When α is greater than 1, the internal quantum yield decreases. This is because an excessively large α causes defects in the crystal structure, resulting in a decrease in the internal quantum yield.

[0016] In the above chemical formula (1), it is preferable that X is Cl and X' is I. That is, when X is Cl, it is preferable to replace a portion of X(Cl) with X'(I). By replacing a portion of X(Cl) with X'(I), it is possible to shift the emission wavelength of the halide phosphor to yellow-red.

[0017] In the above chemical formula (1), it is preferable that A is Li, B is Zr, X is Cl, X' is I, and 0<α≦3. In this case, when X is Cl, a part of X(Cl) is substituted with X'(I). That is, the compound represented by the above chemical formula (1) is Li2ZrCl 6-α I' αand it is preferable that 0<α≦3. Specific examples of the compound include Li2ZrCl 5.8 I 0.2 In principle, it is difficult to completely separate Zr and Hf at the raw material stage, and Hf is partially contained in the Zr site.

[0018] In the above chemical formula (1), it is preferable that A is Na, B is Zr, X is Cl, X' is I, and 0<α≦3. In this case, too, when X is Cl, a part of X(Cl) is substituted with X'(I). That is, the compound represented by the above chemical formula (1) is Na2ZrCl 6-α I' α and it is preferable that 0<α≦3. Specific examples of the compound include Na2ZrCl 5.8 I 0.2 In principle, it is difficult to completely separate Zr and Hf at the raw material stage, and Hf is partially contained in the Zr site.

[0019] In the above chemical formula (1), it is preferable that A is Cs, B is Zr, X is Cl, X' is I, and 0<α≦3. That is, the compound represented by the above chemical formula (1) is CsZrCl 6-α I' α and it is preferable that 0<α≦3. Specific examples of the compound include Cs2ZrCl 5.8 I 0.2 In principle, it is difficult to completely separate Zr and Hf at the raw material stage, and Hf is partially contained in the Zr site.

[0020] The present invention provides a method for changing the emission wavelength of a rare-earth-free self-luminous halide phosphor, A2BX6, by substituting elements at each site. As a result, the halide phosphor of this embodiment exhibits broad emission from yellow to red without containing any rare-earth elements. Furthermore, when X' is I in the compound represented by the above chemical formula (1), the internal quantum yield is improved and the phosphor emits light with high efficiency compared to when I is not contained. This can contribute to fields related to white LEDs, primarily for lighting, which use yellow-red phosphors that have a low environmental impact and are made from stably supplied raw materials.

[0021] [Method for synthesizing halide phosphors] A halide fluorescent material made of a compound represented by the above chemical formula (1) can be synthesized, for example, by the synthesis method shown below. A compound containing element A in the above chemical formula (1) and a compound containing element B in the above chemical formula (1) are prepared. The compounds containing element A are compounds of element A and element X in the above chemical formula (1) (compound a), and compounds of element A and element X' in the above chemical formula (1) (compound b). The compounds containing element B are compounds of element B and element X or X' (compound c). In a nitrogen atmosphere, compounds a, b, and c in a stoichiometric ratio are crushed and mixed in a mortar, and then vacuum sealed in a quartz glass tube. Thereafter, the mixture, which is vacuum sealed in a quartz glass tube, is heated in an electric furnace and melted to synthesize a halide phosphor made of the compound represented by the above chemical formula (1).

[0022] The temperature to which the mixture vacuum-sealed in the quartz glass tube is heated is preferably 25°C or higher and 1200°C or lower, more preferably 600°C or higher and 1000°C or lower, and even more preferably 800°C or higher and 900°C or lower. If the temperature is above the lower limit, the raw material powder will melt completely. If the temperature is below the upper limit, the increase in internal pressure can be suppressed, preventing the quartz glass tube from bursting.

[0023] [Light-emitting device] FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device according to one embodiment of the present invention. The size of each component in the drawings has been appropriately exaggerated for ease of explanation and does not represent the actual dimensions or ratios between components. In this specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals, and redundant explanations will be omitted. As shown in Fig. 1, the light emitting device 1 of this embodiment includes a substrate 2, a light emitting element (LED chip) 3, and a sealing member 4. The substrate 2 has a recess 21. The light emitting element 3 is disposed on a bottom surface 21a of the recess 21 of the substrate 2. The light emitting element 3 is covered in the recess 21 by the sealing member 4 and is sealed in the sealing member 4. The sealing member 4 includes a sealing resin 5 and a phosphor 6.

[0024] In the sealing member 4, phosphor 6 is dispersed.

[0025] (phosphor) The phosphor 6 in this embodiment is the halide phosphor of the above-described embodiment.

[0026] (Sealing resin) The sealing resin 5 is the main component of the sealing member 4 in this embodiment. In this embodiment, a sealing material containing the sealing resin 5 and the phosphor 6 is cured to form the sealing member 4, and the light-emitting element 3 is sealed with the sealing member 4. As a result, deterioration factors from the external environment, such as moisture and oxygen, are prevented from reaching the light-emitting element 3. In this embodiment, the cured sealing resin 5 is basically transparent, and can transmit light emitted from the light-emitting element 3.

[0027] The content of the sealing resin 5 in the sealing member 4 is not particularly limited as long as it can seal the light emitting element 3, and can be the balance of the other components.

[0028] Such sealing resin 5 is not particularly limited as long as it can be used as a sealing material. As the sealing resin 5, for example, resins such as silicone resins and epoxy resins may be used alone or in combination of two or more. As the silicone resin, a phenyl-based silicone resin or a methyl-based silicone resin may be used. From the viewpoint of durability, a methyl-based silicone resin is particularly preferred.

[0029] The methyl silicone resin may refer to, for example, a resin having a siloxane bond in which silicon and oxygen are alternately bonded as a main skeleton, and in which most of the functional groups bonded to Si atoms are methyl groups. However, the methyl silicone resin is not limited to this example. As the methyl-based silicone resin, for example, dimethyl silicone resin, methyl phenyl silicone resin, etc. can be used.

[0030] The structure of the sealing resin 5 in this embodiment may be a two-dimensional chain structure, a three-dimensional network structure, or a cage structure. The sealing resin 5 may be in a cured polymer state when used as the sealing member 4. In the sealing material, the sealing resin 5 may be in a pre-cured state, i.e., a precursor. Therefore, the sealing resin present in the sealing material may be, for example, a monomer, an oligomer, or a polymer.

[0031] The sealing resin 5 may be of an addition reaction type, a condensation reaction type, or a radical polymerization reaction type.

[0032] The thickness and shape of the sealing member 4 can be adjusted appropriately depending on the desired application and properties, and are not particularly limited.

[0033] (light-emitting element) Examples of the light-emitting element 3 include a light-emitting diode (LED) and an organic light-emitting diode (OLED). The sealing member 4 of this embodiment is particularly suitable for sealing a light-emitting diode. The light-emitting device 1 of this embodiment is preferably a light-emitting device using a blue LED chip, a red LED chip, and a green LED chip.

[0034] According to the light emitting device 1 of this embodiment, since the sealing member 4 contains the halide phosphor of the above-described embodiment as the phosphor 6, the light emitted from the light emitting element 3 is excellent in extraction efficiency.

[0035] (Method of manufacturing a light-emitting device) The manufacturing method of the light-emitting device of this embodiment is the same as the manufacturing method of the light-emitting device 1 of this embodiment described above, and includes the steps of applying a sealing material containing a phosphor 6 and a sealing resin 5 onto the light-emitting element 3, curing the sealing material to form a sealing member 4, and sealing the light-emitting element 3 with the sealing member 4. In the method for manufacturing a light emitting device according to this embodiment, no solvent is added in the process of mixing the sealing material.

[0036] The method for sealing the light emitting element 3 with the sealing member 4 obtained by curing the sealing material is not particularly limited, and the light emitting element 3 can be sealed in the same manner as with conventional sealing members. For example, the sealing material of this embodiment can be applied onto the light emitting element 3 using a dispenser or the like, and then the sealing material can be cured. Examples of the curing method include heat curing, electron beam curing, etc. More specifically, the sealing resin 5 in the sealing material of this embodiment is cured by an addition reaction or a polymerization reaction to obtain the sealing member 4. [Example]

[0037] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0038] [Example 1] LiCl, LiI, and ZrCl4 were crushed and mixed in a mortar in a stoichiometric ratio under a nitrogen atmosphere, and then vacuum sealed in a quartz glass tube. It is theoretically difficult to completely separate ZrCl4 and HfCl4 at the raw material stage, as Hf is partially contained in the Zr site. The mixture, vacuum sealed in the quartz glass tube, was then heated to 900°C in an electric furnace and melted to produce Li2ZrCl6 and Li2ZrCl. 5.8 I 0.2 was synthesized. Under a nitrogen atmosphere, the obtained Li2ZrCl6 and Li2ZrCl 5.8 I 0.2 was crushed in a mortar. Then, using a Rigaku Smart Lab X-ray diffractometer, Li2ZrCl6 and Li2ZrCl 5.8 I 0.2 The crystal structure of was analyzed. The results of the crystal structure analysis are shown in Figure 2. In addition, the obtained Li2ZrCl6 and Li2ZrCl 5.8 I 0.2 The powder was crushed in a mortar and filled into a quartz cell. The surface of the quartz cell was smoothed, and then the absolute PL quantum yield measurement system C9920-02 manufactured by HAMAMATSU PHOTONICS was used to measure the PL quantum yield of Li2ZrCl6 and Li2ZrCl4 while changing the excitation wavelength from 230 nm to 500 nm in 2 nm increments. 5.8 I 0.2 The emission spectrum of the sample was measured. The emission spectrum with the maximum emission intensity and the excitation spectrum corresponding to that wavelength are shown in Figure 3. Furthermore, the chromaticity coordinates were calculated from the emission spectrum shown in Figure 3 and are shown in Table 1.

[0039] [Example 2] Under a nitrogen atmosphere, NaCl, NaI, and ZrCl4 were crushed and mixed in a mortar in a stoichiometric ratio, and then vacuum sealed in a quartz glass tube. It is theoretically difficult to completely separate ZrCl4 and HfCl4 at the raw material stage, as Hf is partially contained in the Zr site. The mixture, vacuum sealed in the quartz glass tube, was then heated to 900°C in an electric furnace and melted to produce Na2ZrCl6 and Na2ZrCl. 5.8 I 0.2 was synthesized. Under a nitrogen atmosphere, the obtained Na2ZrCl6 and Na2ZrCl 5.8 I 0.2 was crushed in a mortar. Then, using a Rigaku Smart Lab X-ray diffractometer, Na2ZrCl6 and Na2ZrCl 5.8 I 0.2 The crystal structure of was analyzed. The results of the crystal structure analysis are shown in Figure 2. In addition, under a nitrogen atmosphere, the obtained Na2ZrCl6 and Na2ZrCl 5.8 I 0.2 The powder was crushed in a mortar and filled into a quartz cell. The surface of the quartz cell was smoothed, and then the absolute PL quantum yield measurement system C9920-02 manufactured by Hamamatsu Photonics Co., Ltd. was used to measure the PL quantum yield of Na2ZrCl6 and Na2ZrCl6 while changing the excitation wavelength from 230 nm to 500 nm in 2 nm increments. 5.8 I 0.2 The emission spectrum of the sample was measured. The emission spectrum with the maximum emission intensity and the excitation spectrum corresponding to that wavelength are shown in Figure 4. Furthermore, the chromaticity coordinates were calculated from the emission spectrum shown in Figure 4 and are shown in Table 1.

[0040] [Example 3] Under a nitrogen atmosphere, stoichiometric ratios of CsCl, CsI, and ZrCl4 were crushed and mixed in a mortar and then vacuum sealed in a quartz glass tube. It is theoretically difficult to completely separate ZrCl4 and HfCl4 at the raw material stage, as Hf is partially contained in the Zr sites. The mixture, vacuum sealed in the quartz glass tube, was then heated to 900°C in an electric furnace and melted to produce Cs2ZrCl6 and Cs2ZrCl. 5.8 I 0.2 was synthesized. Under a nitrogen atmosphere, the obtained Cs2ZrCl6 and Cs2ZrCl 5.8 I 0.2 was crushed in a mortar. Then, using a Rigaku Smart Lab X-ray diffractometer, Cs2ZrCl6 and Cs2ZrCl 5.8 I 0.2 The crystal structure of was analyzed. The results of the crystal structure analysis are shown in Figure 2. In addition, under a nitrogen atmosphere, the obtained Cs2ZrCl6 and Cs2ZrCl 5.8 I 0.2 The powder was crushed in a mortar and filled into a quartz cell. The surface of the quartz cell was smoothed, and then the absolute PL quantum yield measurement system C9920-02 manufactured by Hamamatsu Photonics Co., Ltd. was used to measure the PL quantum yield of Cs2ZrCl6 and Cs2ZrCl6 while changing the excitation wavelength from 230 nm to 500 nm in 2 nm increments. 5.8 I 0.2 The emission spectrum of the Cs2ZrCl was measured. The emission spectrum with the maximum emission intensity and the excitation spectrum corresponding to that wavelength are shown in Figure 5. The blank spectrum and the excitation spectrum of Cs2ZrCl at an excitation wavelength of 375 nm were also measured. 5.8 I 0.2 The emission spectrum of this material was measured, and the internal quantum yield was calculated. The results are shown in Figure 6. Furthermore, the chromaticity coordinates were calculated from the emission spectrum shown in Figure 5, and the results are shown in Table 1.

[0041] From the results shown in Figure 2, it was confirmed that the X-ray diffraction peaks of Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 without iodine addition in Examples 1-3 matched with the X-ray diffraction peaks of Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 in previous studies (Non-Patent Documents 8, 9, and 10). Furthermore, from the X-ray diffraction peaks of Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 in Examples 1-3, it was also confirmed that the obtained Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 did not contain impurity phases. Furthermore, the X-ray diffraction peaks of Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 with iodine addition were consistent with each other. 5.8 I 0.2 , Na2ZrCl 5.8 I 0.2 , Cs2ZrCl 5.8 I 0.2 The same peaks as those of Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 without iodine addition were also confirmed. 5.8 I 0.2 , Na2ZrCl 5.8 I 0.2 , Cs2ZrCl 5.8 I 0.2It was confirmed that Li2ZrCl6, Na2ZrCl6, and Cs2ZrCl6 without iodine addition have the same crystal structure. 5.8 I 0.2 , Na2ZrCl 5.8 I 0.2 , Cs2ZrCl 5.8 I 0.2 It was also confirmed that the product does not contain any impurity phases.

[0042] From the results shown in Figures 3 and 4, it was found that the emission wavelength of Li2ZrCl6 in Example 1 was 475 nm, and the emission wavelength of Na2ZrCl6 in Example 2 was 500 nm. From the results shown in FIG. 5, the emission wavelength of Cs2ZrCl6 in Example 3 was 456 nm, and the same results as those in Non-Patent Document 7 were obtained. From these results, it was confirmed that when A in the above chemical formula (1) was replaced from Cs to Li or Na, the emission wavelength changed without any change in the crystal structure.

[0043] From the results shown in Figure 3-5, it was confirmed that the emission wavelength and excitation wavelength were lengthened by substituting a portion of Cl with I in Example 1-3, and it was found that broad emission was achieved even from 600 nm to 700 nm. From these results, it was found that the emission wavelength can be changed and shifted to a longer wavelength by substituting a portion of Cl with a trace amount of I.

[0044] From the results shown in FIG. 6, it can be seen that in Example 3, Cs2ZrCl 5.8 I 0.2 The internal quantum yield of Cs2ZrCl6 was 85%. Since the internal quantum yield of Cs2ZrCl6 without added iodine is about 50%, it was found that by partially substituting iodine in Cs2ZrCl6, the internal quantum yield can be improved by more than 30%.

[0045] The chromaticity coordinates were calculated from the emission spectrum shown in Figure 3-5 and are shown in Table 1.

[0046] [Table 1]

[0047] As can be seen from the results shown in Table 1, it was confirmed that the addition of iodine caused a shift from the blue region to the yellow-red region.

[0048] As shown in the above examples, by selecting appropriate elements for A, B, X, and X' in the above chemical formula (1) and controlling the halogen ratio α, the emission wavelength can be changed, demonstrating that it is possible to synthesize a phosphor that exhibits a yellow to red color. Furthermore, it was revealed that the internal quantum yield can be improved by partially substituting iodine in Cs2ZrCl6. [Explanation of symbols]

[0049] 1. Light-emitting device 2 boards 3 Light-emitting element 4 Sealing member 5 Sealing resin 6. Phosphors 21 Recess

Claims

1. A halide fluorescent material comprising a compound represented by the following chemical formula (1): A ２ BX ６－α X’ α (1) (In formula (1), A is at least one selected from the group consisting of Cs, Rb, K, Na, and Li; B is at least one selected from the group consisting of Hf, Zr, and Ti; and X and X′ are at least one selected from the group consisting of Cl, Br, and I.)

2. 2. The halide phosphor according to claim 1, wherein in said chemical formula (1), 0<α≦3.

3. 2. The halide phosphor according to claim 1, wherein X is Cl and X' is I in the chemical formula (1).

4. 2. The halide phosphor according to claim 1, wherein, in said chemical formula (1), A is Li, B is Zr, X is Cl, X' is I, and 0<α≦3.

5. 2. The halide phosphor according to claim 1, wherein, in said chemical formula (1), A is Na, B is Zr, X is Cl, X' is I, and 0<α≦3.

6. 2. The halide phosphor according to claim 1, wherein, in said chemical formula (1), A is Cs, B is Zr, X is Cl, X' is I, and 0<α≦3.

7. a light-emitting element and a sealing member that seals the light-emitting element, A light emitting device, wherein the sealing member contains the halide phosphor according to any one of claims 1 to 6.

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