JPWO2018143198A1 - Light emitting device and phosphor - Google Patents

Abstract

The present invention relates to a novel infrared light emitting phosphor that emits light in a wavelength range where the sensitivity of the Si detector is high, a semiconductor light emitting element that emits light in a wavelength region of ultraviolet light or visible light, and a red including the infrared light emitting phosphor. An object of the present invention is to provide an external light emitting device, and the subject is a semiconductor light emitting element that emits ultraviolet light or visible light, and a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light emitting element and emits light in the infrared region. The emission peak wavelength in the infrared region of the phosphor that emits light in the infrared region is between 700 and 1000 nm, and the half width of the waveform of the emission peak is less than 60 nm. This is solved by the light emitting device.

Description

  The present invention relates to an infrared light emitting phosphor and a light emitting device including a semiconductor light emitting element and an infrared light emitting phosphor.

As a light-emitting device that emits infrared light, an infrared light-emitting diode made of a GaAs compound semiconductor is known, and the infrared light-emitting diode is widely used in the area of sensors and the like.
However, the GaAs compound semiconductor light emitting diode has problems such as poor temperature characteristics and low versatility. In addition, infrared light emitting diodes made from GaAs compound semiconductors cause fluctuations in the emission wavelength between products due to subtle changes in manufacturing conditions, and the yield of infrared light emitting diodes decreases in order to obtain a predetermined emission wavelength. There was also the problem of high prices. Therefore, a better infrared light emitting device that can solve these problems has been desired. Therefore, attempts have been made to produce an infrared light emitting device by combining a highly versatile GaN-based compound semiconductor light emitting diode element and an infrared light emitting phosphor.

Patent Document 1 discloses a GaN-based compound semiconductor blue light-emitting diode element, a YAG: Ce, Er-based phosphor that absorbs blue light and emits yellow and infrared light, and a filter that does not transmit ultraviolet light or visible light. A light emitting device is disclosed.
Patent Document 2 discloses an infrared light emitting LED using an infrared light emitting phosphor material on a light source. Specifically, in yttrium gallium garnet (YGG), a combination of an infrared light emitting phosphor material using Cr as a sensitizer and Nd, Yb, Er as light emitting ions, and an LED element that emits light at 660 nm. An example is shown.

  On the other hand, Patent Document 3 describes an infrared light emitting material YAG: Fe, Er having both magnetic characteristics and infrared light emission characteristics as a light emitting compound used in a specific authentication system.

As another example of an infrared light emitting phosphor, Non-Patent Document 1 discloses that a phosphor using LaMgAl ₁₁ O ₁₉ as a base crystal and activating Cr ³⁺ emits light at 692 nm.
Non-Patent Document 2 discloses a fluorescent material in which La ₃ GaGe ₅ O ₁₆ is used as a base crystal and Cr ³⁺ is activated as a material that emits light at 700 nm.
As another example of an infrared emitting phosphor, Non-Patent Document 3 discloses that a phosphor in which LaMgAl ₁₁ O ₁₉ is used as a base crystal and Cr ³⁺ and Nd ³⁺ are co-activated emits light at 1060 nm and 1080 nm. It is disclosed.
On the other hand, Non-Patent Document 4 discloses a fluorescent material in which LaMgAl ₁₁ O ₁₉ is used as a base crystal and Tm ³⁺ and Dy ³⁺ are co-activated as a material exhibiting visible light emission at 450 nm and 570 nm.
Further, Non-Patent Document 5 discloses an infrared light emitting material in which Cr ³⁺ and Tm ³⁺ are co-activated on germanium fluoride glass.

JP 2011-233586 A JP 2012-531043 A Special table 2013-508809 gazette

Materials Research Bulletin, 60: 397-400 (2014) Optical Materials Express, 6: 1247-1255 (2016) Materials Research Bulletin, 74: 9-14 (2016) J. Am. Ceram. Soc., 98 (3): 788-794 (2015) AIP ADVANCES 4, 107145 (2014)

  In YAG: Ce, Er, which is an infrared light emitting phosphor disclosed in Patent Document 1, since the emission wavelength is around 1500 nm, it is received at a wavelength that is longer than the range in which Si as the light receiving element of the detector can be detected. However, there was a problem that it could not be detected by the detector. In addition, the phosphor has a problem that it can be excited only in blue. Furthermore, since a phosphor that emits visible light strongly is used, it is necessary to use means such as a filter in order to manufacture a light emitting device that can obtain only infrared light, and the structure of the light emitting device is complicated. There was a problem.

  The infrared light emitting phosphor materials used in Patent Document 2 all emit light in a wavelength region of 1000 nm or more, and there is a problem that light is emitted in a wavelength region where the detection sensitivity of the Si detector is low. In addition, the types of transition metal elements and rare earth elements generally known in the phosphor-related technical literature as sensitizers and luminescent ions are listed. Which sensitizer and luminescent ion can be combined? It is unclear whether a phosphor having excitation characteristics and emission characteristics suitable for the purpose can be obtained.

  The infrared light emitting material described in Patent Document 3 has a problem in that the host lattice contains a large amount of elements such as Fe that have magnetic characteristics, and the light emission characteristics are significantly reduced. In addition, since the emission of Er is in the vicinity of 1500 nm, as described above, there is a problem that the wavelength is longer than the detection range of the detector and cannot be detected by the detector.

In the infrared light emitting phosphors described in Non-Patent Documents 1 and 2, since the emission wavelengths are 692 nm and 700 nm, there is a problem that it is difficult to distinguish from visible light. Conventionally known phosphors using Cr ³⁺ as an activating ion are generally not affected by visible light emission, and are not known to exhibit light emission in a wavelength range suitable for detection by a Si detector. In other words, it was not a phosphor suitable for an infrared light emitting device.

  In the infrared light emitting phosphor described in Non-Patent Document 3, since the emission wavelength is 1000 nm or more, the detector cannot detect even if it receives light longer than the range in which Si, which is the light receiving element of the detector, can be detected. There was a problem.

  The light-emitting material described in Non-Patent Document 4 has a light emission wavelength of 450 nm and 570 nm and is a white light-emitting material that emits visible light when excited by ultraviolet light. Therefore, it cannot be excited in combination with a blue light-emitting diode. In addition, it cannot be used for infrared emission.

  In the infrared light-emitting material described in Non-Patent Document 5, the light emission wavelengths are 1500 nm and 1800 nm. Therefore, the detector cannot detect even if it is received with a wavelength longer than the range in which Si as the light receiving element of the detector can be detected. There was a problem. Furthermore, since glass is used as the base material, the behavior of the activated ions in the crystal structure in a single crystal cannot be predicted. Therefore, the excitation characteristics and light emission characteristics due to the combination of these activated ions when other single crystals are used as a base material cannot be predicted.

  The present invention has been made in view of such a problem, and a novel infrared light emitting phosphor that emits light in a wavelength region where the sensitivity of the Si detector is high, and semiconductor light emission that emits light in a wavelength region of ultraviolet light or visible light. An object is to provide an infrared light emitting device including an element and the infrared light emitting phosphor.

As a result of intensive studies to solve the above problems, the present inventors are infrared emitting phosphors that emit infrared light in a wavelength region where the sensitivity of the Si detector is high, and any semiconductor of ultraviolet, blue, green, and red The present inventors have found an infrared-emitting phosphor that can be excited by light emission from a light-emitting element, and have found that the above-described problems can be solved, thereby reaching the present invention.
That is, the gist of the present invention resides in the following [1] to [22].
[1] A light-emitting device including a semiconductor light-emitting element that emits ultraviolet light or visible light, and a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light-emitting element and emits light in the infrared region. A light emitting device characterized in that an emission peak wavelength in an infrared region of a phosphor emitting in the region is between a wavelength of 700 and 1000 nm, and a half width of a waveform of the emission peak is less than 60 nm.
[2] The light emitting device according to [1], wherein the phosphor that emits light in the infrared region contains at least Tm or Cr as an activating element.
[3] The phosphor that emits light in the infrared region contains at least Tm as an activating element, and further contains at least one element selected from the group consisting of rare earth metal elements and transition metal elements. ] Or the light emitting device according to [2].
[4] The light emitting device according to [3], wherein at least one element selected from the group consisting of the rare earth metal element and the transition metal element is at least one element selected from Cr, Mn, Sm, and Cu.
[5] The light emitting device according to [4], wherein at least one element selected from the group consisting of the rare earth metal element and the transition metal element is Cr.
[6] The minimum reflectance (%) between a wavelength of 350 and 700 nm of the phosphor emitting in the infrared region is lower than the minimum reflectance (%) between a wavelength of 700 and 800 nm. The light emitting device according to any one of [1] to [5], wherein the difference is 20% or more.
[7] The light emitting device according to any one of [1] to [6], wherein an emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting element is between 300 and 700 nm.
[8] It contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm. And a phosphor.
(M1 _ab M2 _b ) ₃ (M3 _cd M4 _d ) ₅ O ₁₂ (1-2)
Where M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements, and M2 represents the rare earth element essentially including Tm. One or more rare earth metal elements (excluding Sc) different from M1 as a metal element are shown, and M3 is B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and One or more metal elements selected from Hf, M4 represents one or more metal elements selected from Cr and Mn, O represents oxygen, and 0 <a <1, 0 <b ≦ 0. 5, 0 <c <1, 0 <d ≦ 0.5.
[9] The phosphor according to [8], wherein the crystal phase is a crystal phase having a garnet structure.
[10] It contains a crystal phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm. And a phosphor.
(A1 _1-a A2 _a ) ₂ (A3 _1-b A4 _b ) ₂ O ₆ (2-1)
Wherein A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than Tm and alkaline earth metal elements other than Mg, and A2 represents the rare earth metal element essentially including Tm or Nd. A1 represents one or more metal elements different from A1, and A3 represents one or more metal elements selected from Mg, Co, and Zn, and A4 represents Cr or Mn. One or more metal elements selected from Ni, Fe, and Cu, and one or more metal elements selected from B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, and Hf , Represents two or more metal elements, O represents oxygen, and 0 <a ≦ 0.5 and 0 <b ≦ 0.75.
[11] The phosphor according to [10], wherein the crystal phase is a crystal phase having a double perovskite structure.
[12] The phosphor according to [10] or [11], wherein in the formula (2-1), A4 is two or more metal elements containing Mn and Ge.
[13] It contains a crystal phase having a chemical composition represented by the following formula (3-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 1000 nm. And a phosphor.
_{(D1 1-a-b D2} a D3 b) (D4 1-a D5 11 + a-c D6 c) O 19 ··· (3-1)
However, D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc), and D2 represents one or more metal elements selected from Ca, Sr, and Ba. D3 represents one or more rare earth metal elements (except for Sc) different from D1 as the rare earth metal element, in which Tm is essential, and D4 is one or more selected from Mg and Zn D5 represents one or more metal elements selected from Al, Ga, In, and Sc, and D6 represents one or more metals selected from Cr, Mn, Ni, Fe, and Cu. Represents an element, O represents oxygen, and 0 ≦ a ≦ 0.99, 0 <b ≦ 0.2, and 0 <c ≦ 2.2.
[14] The phosphor according to [13], wherein the crystal phase is a crystal phase having a magnetplumbite structure.
[15] The phosphor according to [13] or [14], wherein in the formula (3-1), D6 contains at least Cr.
[16] It includes a crystal phase having a chemical composition represented by the following formula (4-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 700 and 1000 nm. And a phosphor.
E1 ₅ (E2 _1-a E3 _a ) ₄ O ₁₅ (4-1)
E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of Ca, Sr, and Ba, and E2 represents Al, Ga, In, Sc, Y, Ti, Zr, Si, One or more metal elements selected from Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W; E3 is one or more metal elements different from E2 selected from transition metal elements O represents oxygen and 0 <a <0.2.
[17] The phosphor according to [16], wherein the crystal phase is a crystal phase having a hexagonal perovskite structure.
[18] The phosphor according to [16] or [17], in which, in the formula (4-1), E2 contains at least Al.
[19] The phosphor according to any one of [16] to [18], in which, in the formula (4-1), E3 contains at least Cr.
[20] It contains a crystal phase having divalent samarium (Sm) and trivalent thulium (Tm) as activators in the host crystal, and absorbs ultraviolet light or visible light, and has a wavelength of 800 to 1000 nm. A phosphor having an emission peak wavelength therebetween.
[21] one or more metals selected from the group consisting of alkali metal elements and alkaline earth metal elements, and one or more metals selected from B, Al, Ga, Si, Ge, and P The phosphor according to [20], further including an element and one or more elements selected from O, F, Cl, and Br.
[22] The phosphor according to [20] or [21], wherein the base crystal contains a crystal phase having a chemical composition represented by the following formula (5-1).
G1 _1-a G2 _a G3 _b O ₅ (5-1)
Where G1 represents one or more metal elements selected from alkaline earth metal elements, G2 represents two or more metal elements selected from rare earth metal elements that require Sm and Tm, and G3 represents , B, Al, Ga, Si, Ge, and P, O represents oxygen, 0 <a <0.2, 1.5 <b <2.5 It is.

According to the present invention, a novel infrared light emitting phosphor that emits light in a wavelength range where the detection sensitivity of the Si detector is high, specifically, an emission peak wavelength in the infrared region is between 700 and 1000 nm, A novel infrared light emitting phosphor having a half-value width of an emission peak waveform of less than 60 nm, and a semiconductor light emitting element that emits light in a wavelength region of ultraviolet light or visible light, and an infrared light emitting device including the infrared light emitting phosphor Can be provided. Further, it is possible to provide a light emitting device that can obtain only desired infrared light emission without taking a complicated configuration such as a filter.
The infrared-emitting phosphor is a phosphor having a high emission efficiency because it emits light of a desired infrared wavelength and emits very little light at other wavelengths. In addition, the emission wavelength of the infrared light-emitting phosphor is determined by the type of the activation element and does not change. Therefore, when the infrared light-emitting phosphor is used in a light-emitting device, there is no wavelength fluctuation between the light-emitting devices. Infrared light emitting devices that emit light at a predetermined light emission wavelength can be provided at low cost.

The emission spectra of the phosphors of Example 1-1 and Comparative Example 1-1 are shown. The excitation spectrum of the fluorescent substance of Example 1-1 and Comparative Example 1-1 is shown. The XRD pattern of the fluorescent substance of Example 1-1 is shown. The emission spectrum of Example 1-2 is shown. The emission spectra of the phosphors of Example 2-1 and Comparative Example 2-1 are shown. The excitation spectrum of the fluorescent substance of Example 2-1 and Comparative Example 2-1 is shown. The XRD pattern of the fluorescent substance of Example 2-1 is shown. The emission spectrum of the phosphor of Example 2-2 is shown. The excitation spectrum of the fluorescent substance of Example 2-2 is shown. The XRD pattern of the fluorescent substance of Example 2-2 is shown. The emission spectrum of the light-emitting device of Example 2-3 is shown. The emission spectrum of the light-emitting device of Example 2-4 is shown. The emission spectrum of the phosphor of Example 3-1 is shown. The excitation spectrum of the fluorescent substance of Example 3-1 is shown. The XRD pattern of the fluorescent substance of Example 3-1 is shown. The emission spectrum of the phosphor of Example 4-1 is shown. The excitation spectrum of the fluorescent substance of Example 4-1 is shown. The XRD pattern of the fluorescent substance of Example 4-1 is shown. The excitation spectrum (dotted line) and emission spectrum (solid line) of the phosphor of Example 5-1 are shown. The XRD pattern of the fluorescent substance of Example 5-1 is shown.

Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the content demonstrated below, In the range which does not change the summary, it can change arbitrarily and can implement.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Further, in the phosphor composition formula in this specification, each composition formula is delimited by a punctuation mark (,). In addition, when a plurality of elements are listed separated by commas (,), one or two or more of the listed elements may be included in any combination and composition.

{Phosphor}
The phosphor according to the first embodiment of the present invention is an infrared phosphor that absorbs ultraviolet light or visible light emitted from a semiconductor light emitting element and emits light in the infrared region, and has an emission peak wavelength in the infrared region. The wavelength is between 700 and 1000 nm. In the present specification, the phosphor according to the first embodiment of the present invention may be referred to as “infrared phosphor” or “infrared light emitting phosphor”.
Here, the emission peak in the infrared region means the largest emission peak among the emission peaks between wavelengths 730 nm and 1000 nm. Therefore, the emission peak wavelength in the infrared region means a wavelength that produces the largest emission peak among emission peaks between wavelengths 730 nm and 1000 nm.
Further, in this specification, ultraviolet light means light having a wavelength of less than 400 nm, and visible light means light having a wavelength of 400 nm to 700 nm.

[Emission spectrum]
The infrared phosphor according to the first embodiment preferably has the following characteristics when an emission spectrum is measured by excitation with light having a peak wavelength of 300 nm or more, 700 nm or less, or 650 nm or less. The peak wavelength refers to a wavelength that produces the largest emission peak among emission peaks between wavelengths of 300 nm or more, 700 nm or less, or 650 nm or less.

The emission peak wavelength λp (nm) in the above-mentioned emission spectrum is usually 700 nm or more, preferably 730 nm or more, more preferably 750 nm or more, more preferably 770 nm or more, still more preferably 780 nm or more, still more preferably 800 nm or more, Usually 1000 nm or less, preferably 950 nm or less, more preferably 940 nm or less, still more preferably 930 nm or less, even more preferably 900 nm or less, even more preferably 880 nm or less, much more preferably 870 nm or less, and much more preferably 850 nm or less. It is.
It is preferable at the point which has suitable infrared light emission as it is in the said range.

The half-width of the waveform of the emission peak in the infrared region of the infrared phosphor according to the first embodiment is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, and still more preferably less than 60 nm. Even more preferably, it is 50 nm or less, and preferably 1 nm or more.
It is preferable that the half-value width of the waveform of the emission peak in the infrared region is within the above-mentioned range since the consistency with the light receiving element that detects infrared emission emitted from the infrared phosphor tends to be high. In addition, the emission intensity at the desired emission wavelength tends to be particularly high, which is preferable.

In order to excite the infrared phosphor with light having a peak wavelength of 300 nm or more, 700 nm or less, or 650 nm or less, for example, a xenon light source can be used. The emission spectrum of the phosphor obtained in the first embodiment can be measured using, for example, a fluorescence spectrophotometer F-4500 or F-7000 (manufactured by Hitachi, Ltd.). The emission peak wavelength in the infrared region and the half width of the emission peak waveform can be calculated from the obtained emission spectrum.
The half-value width of the waveform of the emission peak in the infrared region may be measured by measuring the half-value width of the waveform of the largest emission peak among the emission peaks between wavelengths 700 and 1000 nm. In the case of being observed overlapping with each other, a half-value width is defined between two wavelengths that are half-valued with respect to the largest emission peak. For example, in the emission spectrum of the phosphor of Example 1-1 in FIG. 1-1, the peak having a peak top at 794 nm (the peak indicated by a black triangle) is the largest emission peak. The half-value width was calculated as a half-value width by measuring between two points of 782.8 nm and 832.4 nm of wavelengths that become half-values (points indicated by black circles).

[Excitation spectrum]
The infrared phosphor according to the first embodiment is usually 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and usually 700 nm or less, preferably 650 nm or less, more preferably 600 nm or less, more preferably 550 nm or less. Have an excitation peak in the wavelength range of. That is, it is excited by light in the near ultraviolet to red region or deep red region.

[Quantum efficiency and absorption efficiency]
The external quantum efficiency (η _o ) in the infrared phosphor according to the first embodiment is usually 3% or more, preferably 4% or more, more preferably 6% or more, still more preferably 25% or more, and still more preferably. 40% or more, still more preferably 50% or more. A higher external quantum efficiency is preferable because the luminous efficiency of the phosphor is increased.
The internal quantum efficiency (η _i ) in the infrared phosphor according to the first embodiment is usually 5% or more, preferably 10% or more, more preferably 15% or more, still more preferably 20% or more, and still more preferably. It is 30% or more, still more preferably 50% or more, particularly preferably 70% or more, and still more preferably 90% or more. Internal quantum efficiency means the ratio of the number of photons emitted to the number of photons of excitation light absorbed by the infrared phosphor. For this reason, the higher the internal quantum efficiency, the higher the emission efficiency and emission intensity of the infrared phosphor, which is preferable.

  The absorption efficiency of the infrared phosphor according to the first embodiment is usually 20% or more, preferably 25% or more, more preferably 30% or more, still more preferably 35% or more, still more preferably 40% or more, More preferably, it is 50% or more, and particularly preferably 60% or more. Higher absorption efficiency is preferred because the luminous efficiency of the phosphor is high and the amount of infrared phosphor used is reduced.

[composition]
The composition of the infrared phosphor according to the first embodiment is not particularly limited as long as it has a desired emission peak wavelength. The composition of the infrared phosphor can be confirmed by a generally known method. For example, fluorescent X-ray analysis, high frequency inductively coupled plasma (ICP) emission analysis, X-ray photoelectron spectroscopic analysis and the like can be mentioned.
The infrared phosphor according to the first embodiment includes an element selected from a rare earth metal element and a transition metal element as an activating element in order that the emission peak wavelength in the infrared region is from 700 to 1000 nm. It is preferable that it contains at least two elements selected from rare earth metal elements and transition metal elements. This is because when an infrared phosphor emits light using ultraviolet light or visible light emitted from a semiconductor light emitting element as an excitation light, it is difficult to increase the wavelength to a desired light emission wavelength with only one kind of activating element. It depends. Therefore, it is preferable to use a combination of an element that acts as a sensitizer and an element that acts as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light. Further, it is preferable that at least one element of Tm, Cr, and Sm is included as the activating element.
In addition, since the half-value width of the emission peak waveform in the infrared region is narrowed and a phosphor having a particularly high emission intensity at a desired emission wavelength can be easily obtained, the following sensitizers and activators that act as emission ions can be obtained. It is preferable to combine appropriately from elements. Thereby, it can be set as the infrared fluorescent substance with high luminous efficiency, without losing the excitation energy from a semiconductor light-emitting device. Examples of the element that functions as a sensitizer include Ce, Eu, Cr, Mn, Cu, and Sm. In addition, examples of elements that function as luminescent ions include Tm, Nd, Cr, and Sm. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is more preferable that the active element contains at least thulium (Tm) and further contains at least one element selected from a rare earth metal element and a transition metal element. . This is because Tm is preferable as an element working as a luminescent ion.

  Moreover, it is preferable that activator elements other than Tm are at least one element among Cr, Mn, Sm, and Cu. These elements are particularly preferable as sensitizers that absorb ultraviolet to visible light and Tm works as a light-emitting ion, and can transition energy with high efficiency in combination with Tm. Among these, the most preferable combination is that the activating elements are Tm and Cr.

[Crystal structure]
In the infrared phosphor according to the first embodiment, if an appropriate element is selected based on the above description, it is related to the type / composition and crystal structure of the element of the lattice crystal constituting the crystal phase of the infrared phosphor. However, it can be adjusted to have a desired emission peak wavelength.
The infrared phosphor according to the first embodiment can have various crystal structures as a crystal phase, such as a perovskite structure, a double perovskite structure, a hexagonal perovskite structure, a garnet structure, and a magnet planbite. Examples include the structure.

[Reflectance]
From the viewpoint of wavelength conversion efficiency, the minimum reflectance (%) between the wavelength 350 and 700 nm of the phosphor that emits light in the infrared region according to the first embodiment is the minimum reflectance between the wavelength 700 and 800 nm. The difference between the two minimum reflectances, which is lower than the reflectance (%), is usually 20% or more, preferably 30% or more, and more preferably 50% or more. It is usually less than 90%.

[Preferred embodiment 1-1]
The infrared phosphor according to the first embodiment contains a crystal phase having a chemical composition represented by the following formula (1-1), absorbs ultraviolet light or visible light, and has a wavelength of 750 to 950 nm. Examples thereof include phosphors having an emission peak wavelength between them. The crystal phase is preferably a crystal phase having a garnet structure.
(M1 _ab M2 _b ) ₃ (M3 _cd M4 _d ) ₅ O ₁₂ (1-1)
However,
M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 represents one or more rare earth metal elements (excluding Sc) different from M1 as the rare earth metal element;
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr, Mn, Fe, Ni, and Cu,
O represents oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.

M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding thulium (Tm) and scandium (Sc)) and alkaline earth metal elements.
Examples of the rare earth metal element include yttrium (Y), lanthanum (La), and the like. However, it is preferable that at least Y is contained because of the low cost of the raw material, and 50 mol% or more of M1 is more preferably Y. More preferably, 80% by mole or more of M1 is Y.
Examples of the alkaline earth metal element include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).
In addition, M1 may be partially substituted with another element within a range that does not impair the effect as the infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like.

  M2 represents one or more rare earth metal elements (excluding scandium (Sc)) different from M1 as the rare earth metal element. Examples of such rare earth metal elements include cerium (Ce), europium (Eu), and thulium (Tm), and are not particularly limited as long as they are elements different from M1, but include at least Tm for the reason of emitting infrared light. It is more preferable that 10 mol% or more of M2 is Tm, and more preferably 50 mol% or more of M2 is Tm.

  M3 is boron (B), aluminum (Al), gallium (Ga), indium (In), scandium (Sc), silicon (Si), germanium (Ge), titanium (Ti), tin (Sn), zirconium ( Zr) and one or more metal elements selected from hafnium (Hf). For the reason that the sensitizer can be easily activated, it is preferable to contain at least Al or Ga, and 10 mol% or more of M3 is more preferably Al and / or Ga, and further preferably Al or Ga.

  M4 represents one or more metal elements selected from chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), and copper (Cu). For reasons of easy absorption of ultraviolet light and visible light, it is preferable to contain at least Cr or Mn, and 10 mol% or more of M4 is preferably Cr and / or Mn, and more preferably Cr or Mn. Moreover, it is preferable that the metal element which has magnetic characteristics, such as Fe, is 50 mol% or less.

  O represents oxygen and may be partially substituted with another element within a range not impairing the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N), and the like.

a represents the content of M1, the range is usually 0 <a <1, the lower limit is preferably 0.7 or more, more preferably 0.8 or more, and the upper limit is preferably 0. .999 or less, more preferably 0.990 or less.
b represents the content of M2, the range is usually 0 <b ≦ 0.5, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably Is 0.3 or less, more preferably 0.2 or less.
c represents the content of M3, the range is usually 0 <c <1, the lower limit is preferably 0.7 or more, more preferably 0.8 or more, and the upper limit is preferably 0. .999 or less, more preferably 0.990 or less.
d represents the content of M4, the range is usually 0 <d ≦ 0.5, and the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably Is 0.3 or less, more preferably 0.2 or less.

[Preferred embodiment 1-2]
As another preferable aspect of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and has a wavelength Examples include phosphors having an emission peak wavelength between 750 and 950 nm. The crystal phase is preferably a crystal phase having a garnet structure.
(M1 _ab M2 _b ) ₃ (M3 _cd M4 _d ) ₅ O ₁₂ (1-2)
However,
M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 represents one or more rare earth metal elements (excluding Sc) different from M1 as the rare earth metal element, in which Tm is essential.
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr and Mn,
O represents oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.

In the present embodiment, the description of the “preferred embodiment 1-1” is used except for the following descriptions of M2 and M4.
M2 represents one or more rare earth metal elements (excluding scandium (Sc)) different from M1 as the rare earth metal element, which essentially includes thulium (Tm).
Examples of such rare earth metal elements include cerium (Ce) and europium (Eu), and are not particularly limited as long as they are elements different from M1, but Tm is essential for the reason of infrared emission, and 10 mol% of M2 The above is more preferably Tm, and more preferably 50 mol% or more of M2 is Tm.
M4 represents one or more metal elements selected from chromium (Cr) and manganese (Mn). For reasons of easy absorption of ultraviolet light and visible light, it is preferable to contain at least Cr or Mn, and 10 mol% or more of M4 is preferably Cr and / or Mn, and more preferably Cr or Mn. Moreover, it is preferable that the metal element which has magnetic characteristics, such as iron (Fe), is 50 mol% or less.

[Preferred Embodiment 1-3]
In the phosphor according to the preferable aspect 1-2, it is more preferable that M2 is Tm in the formula (1-2). That is, it has a chemical composition represented by the following formula (1-3), contains a crystal phase having a garnet structure, absorbs ultraviolet light or visible light, and emits light with a peak wavelength between 750 and 950 nm. It is a Tm ³⁺ activated infrared phosphor characterized by having.
(M1 _ab M2 _b ) ₃ (M3 _cd M4 _d ) ₅ O ₁₂ (1-3)
However,
M1 represents one or more metal elements selected from rare earth metal elements (except Tm and Sc) and alkaline earth metal elements;
M2 represents Tm,
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr and Mn,
O represents oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.

In the present embodiment, the description of the “preferred embodiment 1-1” is used except for the following descriptions of M2 and M4.
M2 represents Tm. By having Tm as the activator element, a high-quality infrared phosphor having an emission peak between wavelengths 750 and 950 nm can be obtained.
M4 represents one or more metal elements selected from chromium (Cr) and manganese (Mn). More preferably, 10 mol% or more of M4 is Cr, and even more preferably Cr. Cr and Mn have strong absorption in ultraviolet light or visible light, and are particularly preferable as a sensitizer for Tm to act as a luminescent ion, and energy transition can be performed with high efficiency by combination with Tm.

[Preferred embodiment 2-1]
As another preferable aspect of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and has a wavelength Examples include phosphors having an emission peak wavelength between 750 and 950 nm. The crystal phase is preferably a crystal phase having a double perovskite structure.
(A1 _1-a A2 _a ) ₂ (A3 _1-b A4 _b ) ₂ O ₆ (2-1)
However,
A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than Tm and alkaline earth metal elements other than Mg;
A2 represents one or more metal elements different from A1 as the rare earth metal element, which essentially requires Tm or Nd,
A3 represents one or more metal elements selected from Mg, Co, and Zn,
A4 is one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu, which must contain Cr or Mn, and B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, And two or more metal elements, including one or more metal elements selected from Hf,
O represents oxygen,
0 <a ≦ 0.5 and 0 <b ≦ 0.75.

A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than thulium (Tm) and alkaline earth metal elements other than magnesium (Mg).
Examples of the rare earth metal elements other than thulium (Tm) include scandium (Sc), yttrium (Y), lanthanum (La), and the like. More preferably, mol% or more is La, more preferably 80 mol% or more of A1 is La, and particularly preferably A1 is La.
Examples of alkaline earth metal elements other than Mg include calcium (Ca), strontium (Sr), and barium (Ba).
A1 may be partially substituted with other elements within a range not impairing the effect as the infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like.

  A2 represents one or more metal elements different from A1 as the rare earth metal element, in which at least thulium (Tm) or neodymium (Nd) is essential. By having Tm or Nd as the activator element, a high-quality infrared phosphor having an emission peak between wavelengths 750 and 950 nm can be obtained. Further, when one or more metal elements different from A1 as the rare earth metal element, such as cerium (Ce) or europium (Eu), are included as activators, these act as sensitizers, Light emission at a wavelength can be increased.

  A3 represents one or more metal elements selected from magnesium (Mg), cobalt (Co), and zinc (Zn). For reasons of low toxicity and not heavy metals, it is preferable to contain at least Mg or Zn, more preferably 10 mol% or more of A3 is Mg and / or Zn, more preferably Mg or Zn, and more preferably Mg. It is particularly preferred.

  A4 is one or more metal elements selected from chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe), and copper (Cu), essentially comprising chromium (Cr) or manganese (Mn) Boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), titanium (Ti), tin (Sn), zirconium (Zr), and hafnium ( 2 or more metal elements including one or more metal elements selected from Hf).

  When A4 contains at least Cr or Mn as an activating element, it functions as a sensitizer, and the emission peak intensity in the wavelength range from 750 to 950 nm can be increased. Cr and Mn have strong absorption in ultraviolet light or visible light, and are particularly preferable as a sensitizer for Tm to act as a luminescent ion, and energy transition can be performed with high efficiency by combination with Tm. A4 preferably contains Cr or Mn, and more preferably contains Mn. The content of Cr and Mn in A4 is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, and more preferably 0.5 mol% or more in terms of the total amount of Cr and Mn. More preferably.

Furthermore, A4 contains a base crystal that easily activates the sensitizer by including one or more metal elements selected from B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, and Hf. Can be configured. A4 preferably contains Ge or Ti, more preferably Ge, because it is easier to activate the sensitizer. The content of Ge and Ti in A4 is preferably 10 mol% or more, more preferably 50 mol% or more, and further preferably 90 mol% or more in terms of the total amount of Ge and Ti. .
Therefore, A4 is preferably two or more metal elements including Mn and Ge.

Ni, Fe, and Cu are also activation elements that function as sensitizers.
The molar ratio of the activating elements (Cr, Mn, Ni, Fe, Cu) in A4 to the metal elements (B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, Hf) constituting the host crystal is , Preferably 0.1: 99.9 to 50:50, more preferably 0.2: 99.8 to 20:80, and particularly preferably 0.5: 99.5 to 10:90. .

  O represents oxygen and may be partially substituted with another element within a range not impairing the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N), and the like.

a represents the content of A2, the range is usually 0 <a ≦ 0.5, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably Is 0.3 or less, more preferably 0.2 or less.
b represents the content of A4, the range is usually 0 <b ≦ 0.75, the lower limit is preferably 0.1 or more, more preferably 0.4 or more, and the upper limit is preferably Is 0.7 or less, more preferably 0.6 or less.

[Preferred Aspect 3-1]
As another preferable aspect of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (3-1), absorbs ultraviolet light or visible light, and has a wavelength Examples include phosphors having an emission peak wavelength between 750 and 1000 nm. The crystal phase is preferably a crystal phase having a magnetplumbite structure.
_{(D1 1-a-b D2} a D3 b) (D4 1-a D5 11 + a-c D6 c) O 19 ··· (3-1)
However,
D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc);
D2 represents one or more metal elements selected from Ca, Sr, and Ba;
D3 represents one or more rare earth metal elements (excluding Sc) different from D1 as the rare earth metal element, which requires Tm.
D4 contains one or more metal elements selected from Mg and Zn,
D5 represents one or more metal elements selected from Al, Ga, In, and Sc;
D6 represents one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu,
O represents oxygen,
0 ≦ a ≦ 0.99, 0 <b ≦ 0.2, 0 <c ≦ 2.2.

D1 represents one or more metal elements selected from rare earth metal elements (excluding Tm and Sc). Examples of rare earth metal elements other than thulium (Tm) and scandium (Sc) include yttrium (Y), gadolinium (Gd), lutetium (Lu), and lanthanum (La). La is preferably contained, more preferably 50 mol% or more of D1 is La, more preferably 80 mol% or more of D1 is La, and particularly preferably D1 is La.
In addition, D1 may be partially substituted with other elements as long as the effect as the infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like.

  D2 represents one or more metal elements selected from calcium (Ca), strontium (Sr), and barium (Ba). It is preferable that at least Ca or Sr is contained because it tends to be a single-phase crystal phase, 10 mol% or more of D2 is more preferably Ca and / or Sr, and 50 mol% or more of D2 is Ca or More preferably, it is Sr.

  D3 represents one or more rare earth metal elements (excluding scandium (Sc)) different from D1 as a rare earth metal element, which essentially includes thulium (Tm). By having Tm as an activator element, a high-quality infrared phosphor having an emission peak between wavelengths 750 and 1000 nm can be obtained. One or more rare earth metal elements different from D1 as the rare earth metal element (excluding Sc) include cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), and europium (Eu). ), Terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb) and the like. When such an element other than Tm is included as an activator element, these act as a sensitizer and can enhance light emission at a desired wavelength.

  D4 represents one or more metal elements selected from magnesium (Mg) and zinc (Zn). More preferably, 10 mol% or more of D4 is Mg, and 50 mol% or more is Mg. Preferably, D4 is particularly preferably Mg.

  D5 represents one or more metal elements selected from aluminum (Al), gallium (Ga), indium (In), and scandium (Sc), and 10 mol% or more of D5 is more preferably Al, More preferably, 50 mol% or more is Al, and it is particularly preferable that D5 is Al.

  D6 represents one or more metal elements selected from chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe), and copper (Cu), and 10 mol% or more of D6 is Cr or Mn. More preferably, 20 mol% or more is preferably Cr or Mn, and 50 mol% or more is particularly preferably Cr or Mn.

  O represents oxygen and may be partially substituted with another element within a range not impairing the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N), and the like.

a represents the content of D2, the range is usually 0 ≦ a ≦ 0.99, the lower limit is preferably 0.01 or more, more preferably 0.1 or more, and the upper limit is preferably Is 0.98 or less, more preferably 0.9 or less.
b represents the content of D3, the range is usually 0 <b ≦ 0.2, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably Is 0.15 or less, more preferably 0.10 or less.
c represents the content of D6, the range is usually 0 <c ≦ 2.2, the lower limit is preferably 0.01 or more, more preferably 0.1 or more, and the upper limit is preferably Is 2.0 or less, more preferably 1.5 or less.

[Preferred embodiment 4-1]
As another preferable aspect of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (4-1), absorbs ultraviolet light or visible light, and has a wavelength. Examples include phosphors having an emission peak wavelength between 700 and 1000 nm. The crystal phase is preferably a crystal phase having a hexagonal perovskite structure.
E1 ₅ (E2 _1-a E3 _a ) ₄ O ₁₅ (4-1)
However,
E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of Ca, Sr, and Ba;
E2 represents one or more metal elements selected from Al, Ga, In, Sc, Y, Ti, Zr, Si, Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W;
E3 represents one or more metal elements different from E2 selected from transition metal elements,
O represents oxygen,
0 <a <0.2.

E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of calcium (Ca), strontium (Sr), and barium (Ba). Examples of the rare earth metal element include lanthanum (La), gadolinium (Gd), lutetium (Lu), and the like, but it is preferable that at least La is contained because of the low cost of the raw material, and 40 mol% or more of E1 is La. More preferably, 60 mol% or more of E1 is more preferably La, and E1 is particularly preferably La.
In addition, E1 may be partially substituted with other elements as long as the effect as the infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like.

E2 is aluminum (Al), gallium (Ga), indium (In), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), silicon (Si), germanium (Ge), tin ( It represents one or more metal elements selected from Sn), magnesium (Mg), zinc (Zn), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), and tungsten (W).
More preferably, 10 mol% or more of E2 is Al, more preferably 20 mol% or more of E2 is Al, and particularly preferably 25 mol% or more of E2 is Al.
Further, 10 mol% or more of E2 is more preferably Ti, 30 mol% or more of E2 is more preferably Ti, and 50 mol% or more of E2 is particularly preferably Ti.
Further, 50 mol% or more of E2 is preferably Al and Ti, 70 mol% or more of E2 is more preferably Al and Ti, and 90 mol% or more of E2 is Al and Ti. preferable.
If the element that acts as an activator is trivalent, such as Cr ³⁺ , the activator is introduced by replacing a part of Al, so that the proportion of Al in E2 is greater than Ti Is preferred. However, there may be a case where the proportion of Ti is larger than that of Al for reasons such as the ease of generating a crystal phase.
From the viewpoint of charge compensation, in the above preferred ratio, a part of Al may be replaced with Ga, In, Sc, and Y, and a part of Ti may be replaced with Zr, Si, Ge, and Sn.

  E3 represents one or more metal elements different from E2 selected from transition metal elements. E3 works as an activator element. Examples of E3 include chromium (Cr), manganese (Mn), vanadium (V), and the like. More preferably, 10 mol% or more of E3 is Cr, 20 mol% or more of E3 is preferably Cr, and 50 mol% or more of E3 is particularly preferably Cr.

  O represents oxygen and may be partially substituted with another element within a range not impairing the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N), and the like.

  a represents the content of E3, the range is usually 0 <a <0.2, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably Is 0.15 or less, more preferably 0.10 or less.

For example, the phosphor according to the present embodiment has a suitable infrared emission in the above range even when Cr ³⁺ that does not exhibit infrared emission at a suitable wavelength in the conventional phosphor is used as an activated ion. It is excellent in that it has In the phosphor having the chemical composition represented by the above formula (4-1), it is not certain how the emission wavelength of the activated ions is adjusted, but the E2 sites activated by Cr ³⁺ have different valences. This is considered to be related to the fact that it is shared by a plurality of metal cations, and the volume and symmetry of a polyhedron formed by an anion coordinated to Cr ³⁺ .

[Preferred embodiment 5-1]
As another preferable aspect of the infrared phosphor according to the first embodiment, the base crystal contains a crystal phase having divalent samarium (Sm) and trivalent thulium (Tm) as the activator elements, and is ultraviolet Examples thereof include phosphors that absorb light or visible light and have an emission peak wavelength between 750 and 1000 nm.

[Preferred embodiment 5-2]
In the phosphor according to the preferred embodiment 5-1, the matrix crystal is one or more elements selected from the group consisting of alkali metal elements and alkaline earth metal elements, boron (B), aluminum (Al), gallium ( One or more metal elements selected from Ga), silicon (Si), germanium (Ge), and phosphorus (P), and oxygen (O), fluorine (F), chlorine (Cl), and bromine (Br) More preferably, it further contains one or more elements selected from the group consisting of:

[Preferred Aspect 5-3]
In addition, the phosphor according to the preferable aspect 5-1 or the phosphor according to the preferable aspect 5-2 includes a crystal phase in which the base crystal has a chemical composition represented by the following formula (5-1). More preferably, it is a phosphor.
G1 _1-a G2 _a G3 _b O ₅ (5-1)
However,
G1 represents one or more metal elements selected from alkaline earth metal elements,
G2 represents two or more metal elements selected from rare earth metal elements that require Sm and Tm,
G3 represents two or more metal elements selected from B, Al, Ga, Si, Ge and P;
O represents oxygen,
0 <a <0.2 and 1.5 <b <2.5.

G1 represents one or more alkaline earth metal elements selected from Mg, Ca, Sr, and Ba, and 50 mol% or more of G1 is preferably Sr and / or Ba, and 70 mol% or more is Sr. And / or Ba is more preferable, and 90 mol% or more is particularly preferably Sr and / or Ba. In addition, G1 may be partially substituted with another element within a range that does not impair the effect as the infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like.
G2 represents two or more rare earth metal elements that require Sm and Tm, and preferably 50 mol% or more of G2 is Sm and Tm, and 70 mol% or more is Sm and Tm. More preferably, 90 mol% or more is particularly preferably Sm and Tm.
G3 represents two or more metal elements selected from B, Al, Ga, Si, Ge and P. Preferably, 50 mol% or more of G3 is B and P, and 70 mol% or more is B and P. It is more preferable that 90 mol% or more is B and P.

<Light emitting device>
A light emitting device according to a second embodiment of the present invention includes a semiconductor light emitting device that emits ultraviolet light or visible light, and a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light emitting device and emits light in the infrared region. The emission peak wavelength in the infrared region of the phosphor emitting in the infrared region is between 700 and 1000 nm, and the half width of the waveform of the emission peak is less than 60 nm.

  The light-emitting device according to the second embodiment includes a semiconductor light-emitting element, which will be described later, as a first light emitter (excitation light source), and a second light emitter that emits infrared light when irradiated with light from the first light emitter. As described above, among the infrared phosphors according to the first embodiment, the emission peak wavelength in the infrared region of the phosphor emitting in the infrared region is between the wavelength 700 and 1000 nm, and the waveform of the emission peak waveform is The light emitting device includes an infrared phosphor having a half width of less than 60 nm. Any one of these infrared phosphors may be used alone, or two or more thereof may be used in any combination and ratio.

[Composition of phosphor]
The specific aspect of the infrared phosphor according to this embodiment uses the first embodiment described above.
As the infrared phosphor according to the present embodiment, the emission peak wavelength in the infrared region is between 700 and 1000 nm, and the half-value width of the waveform of the emission peak is less than 60 nm, Among elements selected from rare earth metal elements and transition metal elements, at least two elements are preferably included. This is because when an infrared phosphor emits light using ultraviolet light or visible light emitted from a semiconductor light emitting element as an excitation light, it is difficult to increase the wavelength to a desired light emission wavelength with only one kind of activating element. It depends. Therefore, it is preferable to use a combination of an element that acts as a sensitizer and an element that acts as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light.

  Among the activating elements, examples of elements that act as sensitizers include Ce, Eu, Cr, Mn, Cu, and Sm. In addition, examples of elements that function as luminescent ions include Tm and Nd. By appropriately combining them, an infrared phosphor having high luminous efficiency can be obtained without losing excitation energy from the semiconductor light emitting device. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is more preferable that the active element contains at least thulium (Tm) and further contains at least one element selected from a rare earth metal element and a transition metal element. . This is because Tm is preferable as an element working as a luminescent ion.

  Further, it is preferable that the activation element other than Tm is at least one element of Cr, Mn, and Cu. These elements are particularly preferable as sensitizers that absorb ultraviolet to visible light and Tm works as a light-emitting ion, and can transition energy with high efficiency in combination with Tm. Among these, the most preferable combination is that the activating elements are Tm and Cr.

[Characteristics of phosphor]
For the specific characteristics of the infrared phosphor according to this embodiment, the first embodiment described above is used.
In particular, from the viewpoint of wavelength conversion efficiency, the minimum reflectance (%) between a wavelength of 350 and 700 nm of a phosphor emitting in the infrared region is the minimum reflectance (%) between a wavelength of 700 and 800 nm. The difference between the two minimum reflectances is usually 20% or more, preferably 30% or more, and more preferably 50% or more. It is usually less than 90%.

[Configuration of light emitting device]
The light emitting device has a first light emitter (excitation light source), and the configuration thereof is limited except that at least the infrared phosphor according to this embodiment described above is used as the second light emitter. It is possible to arbitrarily adopt a known apparatus configuration.
Examples of the device configuration and the light emitting device include those described in Japanese Patent Application Laid-Open No. 2007-291352.
In addition, examples of the form of the light emitting device include a shell type, a cup type, a chip on board, a remote phosphor, and the like.

{Use of light emitting device}
The use of the light emitting device is not particularly limited, and the light emitting device can be used in various fields where a normal infrared light emitting device is used. For example, a light source of an infrared monitoring device, a light source of an infrared sensor, an infrared light source of a medical diagnostic device, a light source of a transmission element such as a photoelectric switch or a video game joystick can be used.

{Semiconductor light emitting device}
The semiconductor light emitting element included in the light emitting device according to this embodiment is not particularly limited as long as it emits ultraviolet light or visible light and functions as an excitation light source. Since it is widely used as a semiconductor light-emitting device, its price is low and it is easy to obtain. Therefore, the emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light-emitting device is between 300 and 700 nm. It is preferable. The said wavelength becomes like this. More preferably, it is 300-650 nm or 350-680 nm, More preferably, it is 300-400 nm, 420-600 nm, 420-480 nm, or 600-650 nm.

<Method for producing phosphor>
The manufacturing method of the infrared phosphor according to the first embodiment includes a step of mixing raw materials such as chlorides, fluorides, oxides, carbonates and nitrates of the respective elements, a step of firing, a step of crushing, A step of washing and classification can be included.

[Phosphor material]
As the phosphor material used in the method for producing the phosphor according to the first embodiment, a known material is used as long as the effect of the phosphor according to the first embodiment produced according to this embodiment is not impaired. Can do. For example, chlorides, fluorides, oxides, carbonates, nitrates, and the like of each element can be used, but are not limited to these.

[Mixing process]
The phosphor raw materials are weighed so as to obtain the target composition, mixed sufficiently using a ball mill or the like, then filled into a container, fired at a predetermined temperature and atmosphere, and the fired product may be pulverized and washed. For example, the chlorides, fluorides, oxides, carbonates, nitrates, and the like of the above elements may be weighed and mixed so that the molar ratio of each element matches the molar ratio in the target composition formula.

The mixing method is not particularly limited, and may be either a dry mixing method or a wet mixing method.
Examples of the dry mixing method include a ball mill.
As the wet mixing method, for example, a solvent or a dispersion medium is added to the above-described phosphor raw material, mixed using a mortar and pestle to form a solution or slurry, and then spray-dried, heat-dried, or naturally dried It is the method of drying by etc.
Examples of the solvent or dispersion medium include acetone, methanol, ethanol, 1-propanol, 1-butanol and the like, and ethanol is particularly preferable. The wet mixing time is usually 5 minutes or longer, preferably 15 minutes or longer, more preferably 30 minutes or longer. Further, the mixing may be repeated a plurality of times, usually 1 time or more, preferably 2 times or more, more preferably 3 times or more. In particular, mixing for 15 minutes or more, or mixing twice or more is preferable because the phosphor according to the first embodiment of the present invention can be obtained as the main phase.

[Baking process]
The obtained mixture is filled in a container made of a material having low reactivity with each phosphor raw material. The material of the container used at the time of firing is not particularly limited as long as the effect of the phosphor according to the first embodiment manufactured according to the present embodiment is not impaired, and examples thereof include an alumina container.
Although the firing temperature varies depending on other conditions such as pressure, firing can usually be performed in a temperature range of 300 ° C. or more and 2000 ° C. or less. The maximum temperature reached in the firing step is usually 300 ° C. or higher, preferably 1000 ° C. or higher, more preferably 1300 ° C. or higher, and usually 2000 ° C. or lower, preferably 1700 ° C. or lower. In particular, firing in a temperature range of 1400 ° C. or higher and 1600 ° C. or lower is preferable because the phosphor according to the first embodiment of the present invention may be obtained as the main phase.

If the calcination temperature is too high, defects will be induced in the crystal structure due to atomic defects in the phosphor, and the luminescent properties will tend to be significantly reduced.If the calcination temperature is too low, the progress of the solid phase reaction will tend to be slow. Generation and grain growth may be difficult to proceed.
The pressure during the firing step varies depending on the firing temperature and the like, but is usually 0.01 MPa or more, preferably 0.05 MPa or more, and usually 200 MPa or less, preferably 190 MPa or less.

  The firing atmosphere in the firing step is arbitrary as long as a desired phosphor can be obtained, and specific examples include an air atmosphere, a nitrogen atmosphere, a reducing atmosphere containing hydrogen or carbon, and the like. Among these, a reducing atmosphere is preferable. The number of firings is arbitrary as long as a desired phosphor can be obtained, but after firing once, the obtained fired body may be crushed and then fired again, and the number of firings is not particularly limited. In addition, when firing multiple times, the firing atmosphere may be different.

  The firing time varies depending on the temperature and pressure during firing, but is usually 1 minute or longer, preferably 30 minutes or longer, and usually 72 hours or shorter, preferably 12 hours or shorter. If the firing time is too short, the particles do not grow, so that a phosphor with good characteristics cannot be obtained, and if the firing time is too long, the constituent elements are volatilized, so there is a defect in the crystal structure due to atomic defects. Is induced and a phosphor with good characteristics cannot be obtained.

[Washing process]
You may have the process (washing | cleaning process) which wash | cleans the fluorescent substance obtained by baking before dispersion | distribution and classification.
Impurities mainly used as unreacted residues and raw material unreacted components used when synthesizing phosphors remain in the phosphor, or side reactions tend to be generated in the phosphor slurry. .
In order to improve the characteristics, it is necessary to remove as much as possible unreacted residues and impurities generated during firing. There is no particular limitation on the cleaning method as long as impurities can be removed. For example, the produced phosphor can be washed with an arbitrary solution such as acids such as hydrochloric acid, hydrofluoric acid, nitric acid, acetic acid, sulfuric acid, water-soluble organic solvents, alkaline solutions and mixed solutions thereof. The cleaning solution may contain a reducing agent such as hydrogen peroxide, or the cleaning solution may be heated and cooled as long as the light emission characteristics are not significantly deteriorated.

The time for immersing the phosphor in the cleaning liquid varies depending on the stirring conditions and the like, but is usually 10 minutes or longer, preferably 1 hour or longer, and usually 72 hours or shorter, preferably 48 hours or shorter. Moreover, you may wash | clean several times and may change the kind and density | concentration of the liquid to wash | clean.
In the washing step, after performing the work of immersing and washing the phosphor, the phosphor can be manufactured by filtration and drying. Further, washing using ethanol, acetone, methanol or the like may be put in between.

{Phosphor-containing composition}
The phosphor according to the first embodiment can be used by mixing with a liquid medium. In particular, when the phosphor according to the first embodiment is used for a light emitting device or the like, it is preferable to use the phosphor in a form dispersed in a liquid medium.

[Phosphor]
When it is contained in the composition containing the phosphor according to the first embodiment, the type of the phosphor is not limited, and can be arbitrarily selected from the phosphors according to the first embodiment described above. Moreover, this fluorescent substance may be only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Further, the composition may contain a phosphor other than the phosphor according to the first embodiment as long as the effect of the phosphor according to the first embodiment is not significantly impaired.

[Liquid medium]
The liquid medium used in the composition is not particularly limited as long as the performance of the phosphor according to the first embodiment is not impaired within the intended range. For example, any inorganic material and / or organic material may be used as long as it exhibits a liquid property under desired use conditions, suitably disperses the phosphor according to the first embodiment, and does not cause an undesirable reaction. For example, silicone resin, epoxy resin, polyimide silicone resin, and the like can be used.

[Content of liquid medium and phosphor]
The content of the phosphor and the liquid medium according to the first embodiment in the composition is arbitrary as long as the effect of the phosphor according to the first embodiment is not significantly impaired. It is usually 30% by weight or more, preferably 50% by weight or more, and usually 99% by weight or less, preferably 95% by weight or less based on the whole product.

[Other ingredients]
The composition may contain other components in addition to the phosphor and the liquid medium as long as the effects of the phosphor according to the first embodiment are not significantly impaired. Moreover, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In addition, the values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or the lower limit in each embodiment of the present invention, and the preferred range is the value of the upper limit or the lower limit. And a range defined by a combination of values of the following examples or values of the examples.

{Measuring method}
[Emission spectrum]
The emission spectrum was measured using a fluorescence spectrophotometer F-7000 (manufactured by Hitachi, Ltd.). More specifically, it is irradiated with excitation light of 455 nm at room temperature (25 ° C.) and is 500 nm to 900 nm (in the case of Comparative Example 1-1 and Example 1-1), or 750 nm to 850 nm (Comparative Example 2- 1, emission spectra within the wavelength range of Example 3-1 to Example 3-3, Example 4-1, and Example 4-2 were obtained. The emission peak wavelength was read from the obtained emission spectrum.

[Measurement of light emitting device]
In Example 1-2, Example 2-3, and Example 2-4, the emission spectrum of the infrared light emitting device was measured using a small fiber optical spectrometer USB2000 (manufactured by Ocean Optics). More specifically, the light emitting device was turned on, and an emission spectrum of the light emitting device was obtained in a wavelength range of 300 nm to 900 nm.

[Excitation spectrum]
The excitation spectrum was measured using a fluorescence spectrophotometer F-7000 (manufactured by Hitachi, Ltd.). More specifically, the infrared emission peak is monitored at room temperature (25 ° C.), and is 300 nm to 750 nm (in the case of Comparative Example 1-1 and Example 1-1), or 300 nm to 600 nm (Comparative Example 2- 1, excitation spectra within the wavelength range of Example 3-1 to Example 3-3, Example 4-1, and Example 4-2 were obtained.

[Powder X-ray diffraction measurement]
Powder X-ray diffraction was precisely measured with a powder X-ray diffractometer D8 ADVANCE ECO (manufactured by BRUKER). The measurement conditions are as follows.

Using CuKα tube X-ray output = 40 kV, 25 mA
Divergence slit = automatic detector = semiconductor array detector LYNXEYE, Cu filter used Scanning range 2θ = 5-90 degrees (in the case of Comparative Example 1-1, Example 1-1), or 5-90 degrees (Comparative Example 2- 1, Example 3-1 to Example 3-3, Example 4-1 and Example 4-2)
Reading width = 0.025 degrees

[Reflectance measurement]
In Example 1-1, Example 2-1, Example 3-1, and Example 4-1, the reflectance was measured using a spectrophotometer U-3310 (manufactured by Hitachi, Ltd.). More specifically, BaSO ₄ particles and the phosphor particles of the example were spread on quartz cells. Using the BaSO ₄ particles as a reference sample, the reflectance (%) of the phosphor particles of the example was measured as a relative value to the reflectance of the BaSO ₄ particles in a wavelength range of 300 nm to 900 nm.

(Comparative Example 1-1: Production of phosphor)
The raw materials were blended so that the phosphor obtained after synthesis was Y _2.97 Tm _0.03 Ga ₅ O ₁₂ to produce a YGG: Tm ³⁺ phosphor.
Commercially available Y ₂ O ₃ powder (SY-OR-P-1622 manufactured by Shin-Etsu Chemical Co., Ltd.), Ga ₂ O ₃ powder (90402 manufactured by Mitsui Kinzoku Kogyo Co., Ltd.), and Tm ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd.) TM-04-001) was used. Each raw material was weighed so that the molar ratio of cations was Y: Ga: Tm = 2.97: 5.00: 0.03. These raw materials are wet mixed after adding ethanol in an alumina mortar, the ethanol is naturally dried and then placed in an alumina container, and the container containing the mixed raw materials is a small electric furnace (Superburn, manufactured by Motoyama) And fired at 1500 ° C. for 8 hours in the air to obtain a fired body. The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.

  The emission spectrum of the obtained phosphor is shown in FIG. 1-1, and the excitation spectrum is shown in FIG. The excitation light wavelength of the emission spectrum was 463 nm, and the emission wavelength of the excitation spectrum was 808 nm. FIG. 1-1 shows that the phosphor of this comparative example has an infrared emission peak around 800 nm.

(Example 1-1: Production of phosphor)
YGG: Cr ³⁺ , Tm ³⁺ phosphors were prepared by blending the raw materials so that the phosphor obtained after synthesis was Y _2.97 Tm _0.03 Ga _4.75 Cr _0.25 O ₁₂ .
Commercially available Y ₂ O ₃ powder (SY-OR-P-1622 manufactured by Shin-Etsu Chemical Co., Ltd.), Ga ₂ O ₃ powder (90402 manufactured by Mitsui Kinzoku Kogyo Co., Ltd.), Cr ₂ O ₃ powder (B58840N manufactured by Kishida Chemical Co., Ltd.) , And Tm ₂ O ₃ powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) were used. As in Comparative Example 1-1, each raw material was weighed so that the cation molar ratio was Y: Ga: Cr: Tm = 2.97: 4.75: 0.25: 0.03. Mixing and heating were performed to obtain a phosphor.

An XRD pattern obtained by conducting powder X-ray diffraction measurement on this phosphor is shown in FIG. It turns out that this fluorescent substance consists of single phase YGG. The emission spectrum of the phosphor is shown in FIG. 1-1, and the excitation spectrum is shown in FIG. The excitation light wavelength of the emission spectrum was 440 nm, and the emission wavelength of the excitation spectrum was 825 nm. From FIG. 1-1, it can be seen that the phosphor of the present example has a strong infrared emission peak at an intensity of 6 times or more compared to the phosphor of Comparative Example 1-1 around 800 nm. Specifically, the wavelengths at which peaks are observed in the emission spectrum around 800 nm are 794 nm and 825 nm, and the waveforms of these peaks are observed to overlap, but the half-value widths are 27.4 nm and 16.3 nm, respectively. It was. The overlapping emission peaks were regarded as one emission peak, and the half width of the waveform of the emission peak was measured. As a result, the emission peak wavelength was 794 nm, and the half width of the waveform of the emission peak was 49.5 nm. Moreover, from FIG. 1-2, it turns out that the fluorescent substance of a present Example is excited by the light of the wide wavelength band from blue to red, and emits infrared rays.
Further, the minimum reflectance R1 (%) between the wavelength of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelength of 700 and 800 nm of the phosphor are measured, and the difference R1-R2 (%) Was calculated. The results are shown in Table 1.

(Example 1-2: Production of light emitting device)
An infrared light emitting device was fabricated by combining YGG: Cr ³⁺ , Tm ³⁺ and a blue LED.
The phosphor obtained in Example 1-1 and a thermosetting silicone resin were used as raw materials. Each raw material was weighed so that the weight ratio of phosphor: thermosetting silicone resin = 15: 85. These raw materials were mixed using V-mini300 manufactured by EME, and applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko) to be cured, thereby obtaining a light emitting device. The emission spectrum of the light emitting device is shown in FIG. It can be seen that the light emitting device has a peripheral infrared emission peak at approximately 800 nm.

(Comparative Example 2-1: Production of phosphor)
La ₂ MgGeO ₆ : Tm ³⁺ phosphor was prepared by blending raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgGeO ₆ .
Commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Co., Ltd.), MgO powder (LKG 5947 manufactured by Wako Pure Chemical Industries, Ltd.), GeO ₂ powder (313826 manufactured by High Purity Chemical Research Laboratory), and Tm ₂ O ₃ as raw materials. Powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) was used. Each raw material was weighed so that the molar ratio of cations was La: Mg: Ge: Tm = 1.98: 1.00: 1.00: 0.02. These raw materials are wet mixed after adding ethanol in an alumina mortar, the ethanol is naturally dried and then placed in an alumina container, and the container containing the mixed raw materials is a small electric furnace (Superburn, manufactured by Motoyama) And fired at 1400 ° C. for 8 hours in the air to obtain a fired body. The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.

  The emission spectrum of the obtained phosphor is shown in FIG. 2-1, and the excitation spectrum is shown in FIG. The excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 798 nm. From FIG. 2-1, it can be seen that the phosphor of this comparative example does not have an infrared emission peak around 800 nm.

(Example 2-1: Production of phosphor)
La ₂ MgGeO ₆ : Mn ⁴⁺ , Tm ³⁺ phosphor was prepared by blending raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgGe _0.99 Mn _0.01 O ₆ . .
Commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Co., Ltd.), MgO powder (LKG 5947 manufactured by Wako Pure Chemical Industries, Ltd.), GeO ₂ powder (313826 manufactured by High-Purity Chemical Laboratory), Tm ₂ O ₃ powder as raw materials (TM-040-001 manufactured by Shin-Etsu Chemical Co., Ltd.) and MnO ₂ powder (194474 manufactured by High Purity Chemical Research Laboratory) were used. Comparative Example 2 except that each raw material was weighed so that the cation molar ratio was La: Mg: Ge: Tm: Mn = 1.98: 1.00: 0.99: 0.02: 0.01 The phosphor was obtained by mixing and heating in the same manner as in -1.

An XRD pattern obtained by conducting powder X-ray diffraction measurement on this phosphor is shown in FIG. It can be seen that the phosphor is composed of single-phase _La 2 MgGeO _6.
In addition, the emission spectrum of this phosphor is shown in FIG. 2-1, and the excitation spectrum is shown in FIG. The excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 798 nm. FIG. 2A shows that the phosphor of this example has a strong infrared emission peak around 800 nm. The emission peak wavelength was 798 nm, and the half width of the waveform of the emission peak was 14.4 nm. Further, FIG. 2-2 shows that the phosphor of this example is excited by light in a wide wavelength band from ultraviolet to blue and emits infrared light.
Further, the minimum reflectance R1 (%) between the wavelength of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelength of 700 and 800 nm of the phosphor are measured, and the difference R1-R2 (%) Was calculated. The results are shown in Table 1.

(Example 2-2: Production of phosphor)
La ₂ MgTiO ₆ : Mn ⁴⁺ , Tm ³⁺ phosphor was prepared by blending raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgTi _0.99 Mn _0.01 O ₆ . .
Commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Co., Ltd.), Mg (OH) ₂ powder (manufactured by Kosei Chemical Laboratories 83480D), TiO ₂ powder (LAG 1626 manufactured by Wako Pure Chemical Industries), Tm ₂ O ₃ powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) and MnO ₂ powder (194474 manufactured by High Purity Chemical Laboratory) were used. Each raw material was weighed so that the molar ratio of cations was La: Mg: Ti: Tm: Mn = 1.98: 1.00: 0.99: 0.02: 0.01. Other than that was mixed and heated like Example 2-1, and obtained fluorescent substance.
The XRD pattern obtained by conducting powder X-ray diffraction measurement on this phosphor is shown in FIG. 2-6. It can be seen that the phosphor is composed of single-phase _La 2 MgTiO _6.
The emission spectrum of the phosphor is shown in FIG. 2-4, and the excitation spectrum is shown in bold in FIG. 2-5. The excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 804 nm. 2-4 that the phosphor of this example has a strong infrared emission peak around 800 nm. The emission peak wavelength was 804 nm, and the half width of the waveform of the emission peak was 26.2 nm. Moreover, from FIG. 2-5, it turns out that the fluorescent substance of a present Example is excited by the light of the wide wavelength band from ultraviolet to blue, and emits infrared rays.

(Example 2-3: Production of light emitting device)
An infrared light emitting device was fabricated by combining La ₂ MgGeO ₆ : Mn ⁴⁺ , Tm ³⁺ which is the phosphor obtained in Example 2-1 and a blue LED.
The phosphor obtained in Example 2-1 and a thermosetting silicone resin were used as raw materials. Each raw material was weighed so that the weight ratio of phosphor: thermosetting silicone resin = 15: 85. These raw materials were mixed using V-mini300 manufactured by EME, and applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko) to be cured, thereby obtaining a light emitting device. The emission spectrum of the light emitting device is shown in FIG. It can be seen that the light emitting device has an infrared emission peak around 800 nm.

(Example 2-4: Production of light emitting device)
An infrared light emitting device was produced by combining the phosphor obtained in Example 2-2, La ₂ MgTiO ₆ : Mn ⁴⁺ , Tm ³⁺ and a blue LED.
The phosphor obtained in Example 2-2 and a thermosetting silicone resin were used as raw materials. Other than that was weighed, applied and cured in the same manner as in Example 2-3 to obtain a light emitting device. The emission spectrum of the light emitting device is shown in FIG. It can be seen that the light emitting device has an infrared emission peak around 800 nm.

(Example 3-1: Production of phosphor)
LaMgAl ₁₁ O ₁₉ : Cr ³⁺ , Tm ³⁺ phosphor was prepared by blending raw materials so that the phosphor obtained after synthesis was La _0.95 Tm _0.05 MgAl _10.67 Cr _0.33 O ₁₉ . .
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Research Laboratories), MgO powder (manufactured by Wako Pure Chemical Industries, Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical), Cr ₂ O ₃ powder (Kishida) Chemical Co., Ltd.) and Tm ₂ O ₃ powder (Shin-Etsu Chemical Co., Ltd.) were used. Each raw material was weighed so that the molar ratio of cations was La: Tm: Mg: Al: Cr = 0.95: 0.05: 1.00: 10.67: 0.33. Add 5 wt% of H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) externally to these raw materials, add ethanol in an alumina mortar, wet mix, let the ethanol dry naturally, and then make alumina The container containing the mixed raw material was placed in a small electric furnace (Superburn manufactured by Motoyama Co., Ltd.) and heated at 1500 ° C. for 8 hours in the atmosphere to obtain a fired body. The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.
Further, the minimum reflectance R1 (%) between the wavelength of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelength of 700 and 800 nm of the phosphor are measured, and the difference R1-R2 (%) Was calculated. The results are shown in Table 1.

The emission spectrum of the obtained phosphor is shown by a solid line in FIG. 3-1, and the excitation spectrum is shown by a dotted line in FIG. 3-2. The excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 809 nm.
FIG. 3A shows that the phosphor of this example has an infrared emission peak with a narrow half width at 809 nm. 3-2 that the phosphor of this example is excited by light in a wide wavelength band from ultraviolet to blue and emits infrared light. The half width of the waveform of the emission peak at the emission peak wavelength of 809 nm was 50 nm.
An XRD pattern obtained by conducting powder X-ray diffraction measurement of the phosphor of this example is shown in FIG. It can be seen that the phosphor of this example is made of LaMgAl ₁₁ O ₁₉ .

(Example 3-2: Production of phosphor)
Example 3-2 was carried out in the same manner as Example 3-1 except that the raw materials were blended so that the phosphor obtained after synthesis was La _0.95 Tm _0.05 MgAl _10.89 Cr _0.11 O ₁₉ A phosphor was obtained. Based on the emission spectrum when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, it was confirmed that the phosphor of this example had an infrared emission peak with a narrow half-value width at 801 nm.

(Example 3-3: Production of phosphor)
Example 3-3 was carried out in the same manner as Example 3-1 except that the raw materials were blended so that the phosphor obtained after synthesis was La _0.99 Tm _0.01 MgAl _10.67 Cr _0.33 O ₁₉ A phosphor was obtained. According to the emission spectrum when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, the phosphor of this example was confirmed to have an infrared emission peak with a narrow half width at 798 nm.

(Example 4-1: Production of phosphor)
La ₅ AlTi ₃ O ₁₅ : Cr ³⁺ phosphor was prepared by blending the raw materials so that the phosphor obtained after synthesis was La ₅ Al _0.99 Cr _0.01 Ti ₃ O ₁₅ .
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Research Laboratories), TiO ₂ powder (manufactured by Furuuchi Chemical Co., Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), Cr ₂ O ₃ powder (Kishida Chemical) Used). Each raw material was weighed so that the molar ratio of cations was La: Al: Cr: Ti = 5: 0.99: 0.01: 3. After adding 2 wt% of H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) externally to these raw materials, ethanol was added in an alumina mortar and wet-mixed. The container containing the mixed raw material was placed in a small electric furnace (Superburn manufactured by Motoyama Co., Ltd.) and heated at 1500 ° C. for 8 hours in the atmosphere to obtain a fired body. The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.

The emission spectrum of the obtained phosphor is shown by a solid line in FIG. 4-1, and the excitation spectrum is shown by a dotted line in FIG. 4-2. The excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 753 nm.
FIG. 4A shows that the phosphor of this example has an infrared emission peak with a narrow half width at 753 nm. FIG. 4B also shows that the phosphor of this example is excited by light in a wide wavelength band from ultraviolet to blue and emits infrared light. The half width of the waveform of the emission peak at the emission peak wavelength of 753 nm was 41 nm.

FIG. 4-3 shows an XRD pattern obtained by performing powder X-ray diffraction measurement of the phosphor of this example. It can be seen that the phosphor of this example is mainly made of La ₅ AlTi ₃ O ₁₅ . In addition, the peak shown by the arrow in FIG. 4-3 is LaAlO ₃ by-produced as an impurity phase. The light emission of LaAlO ₃ : Cr is usually light emission having a maximum light emission peak at about 737 nm and a plurality of weak light emission peaks between 735 nm and 755 nm. Therefore, it can be said that the infrared emission peak with a narrow half-value width of 753 nm observed above is derived from La ₅ AlTi ₃ O ₁₅ .
Further, the minimum reflectance R1 (%) between the wavelength of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelength of 700 and 800 nm of the phosphor are measured, and the difference R1-R2 (%) Was calculated. The results are shown in Table 1.

(Example 4-2: Production of phosphor)
La ₅ AlTi ₃ O ₁₅ : Cr ³⁺ phosphor was prepared by blending the raw materials so that the phosphor obtained after synthesis was La ₅ Al _0.95 Cr _0.05 Ti ₃ O ₁₅ .
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Laboratories), TiO ₂ powder (manufactured by Showa Denko), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), Cr ₂ O ₃ powder (Kishida Chemical Co., Ltd.) Made). Each raw material was weighed so that the molar ratio of cations was La: Al: Cr: Ti = 5: 0.95: 0.05: 3. After adding ethanol in an alumina mortar, wet-mix, let the ethanol dry naturally, put it in an alumina container, and place the container containing the mixed raw material in a small electric furnace (Motoyama Superburn). A fired body was obtained by heating at 1600 ° C. for 8 hours in the air. The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.
Based on the emission spectrum when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, it was confirmed that the phosphor of this example had an infrared emission peak with a narrow half-value width at 752 nm.

(Example 5-1: Production of phosphor)
SrBPO ₅ : Sm ²⁺ , Tm ³⁺ phosphor was prepared by blending the raw materials so that the phosphor obtained after synthesis was Sr _0.96 Sm _0.03 Tm _0.01 BPO ₅ .
Commercially available SrHPO ₄ powder (manufactured by Hakuho Chemical Co., Ltd.), Sm ₂ O ₃ powder (manufactured by Mitsuwa Chemical Co., Ltd.), Tm ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd.) and H ₃ BO ₃ powder (Wako Pure Chemical Industries, Ltd.) Manufactured by Kogyo Co., Ltd.). Each raw material was weighed so that the cation molar ratio was Sr: Sm: Tm = 0.96: 0.03: 0.01, mixed, and then put into an alumina container. The sintered body was obtained by installing in a tubular furnace and heating at 950 ° C. for 8 hours in a reducing atmosphere (N ₂ (96%) + H ₂ (4%)). The fired body was crushed in an alumina mortar until there were no large lumps to obtain a phosphor.
The emission spectrum when the obtained phosphor is irradiated with light having a wavelength of 455 nm is shown by a solid line in FIG. 5-1, and the excitation spectrum for the emission wavelength of 810 nm is shown by a dotted line. In FIG. 5A, the half-value width of the waveform of the emission peak between the wavelengths of 800 nm and 850 nm was 23 nm. As can be seen from FIG. 5A, the phosphor of this example is excited in a wide range of wavelengths from 300 nm to 600 nm, and has an infrared emission peak with a narrow half width between wavelengths of 800 nm to 850 nm.

Moreover, the XRD pattern obtained by performing the powder X-ray-diffraction measurement of the fluorescent substance of a present Example is shown to FIGS. 5-2. It can be seen that the phosphor of the present embodiment is composed of SrBPO _5.

Claims (22)

A semiconductor light emitting device emitting ultraviolet light or visible light;
A phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light emitting element and emits light in the infrared region,
A light emitting device characterized in that the emission peak wavelength in the infrared region of the phosphor emitting in the infrared region is between 700 and 1000 nm, and the half width of the waveform of the emission peak is less than 60 nm.   The light emitting device according to claim 1, wherein the phosphor that emits light in the infrared region contains at least Tm or Cr as an activating element.   The phosphor that emits light in the infrared region contains at least Tm as an activator, and further contains at least one element selected from the group consisting of rare earth metal elements and transition metal elements. The light emitting device according to 1.   The light emitting device according to claim 3, wherein at least one element selected from the group consisting of the rare earth metal element and the transition metal element is at least one element selected from Cr, Mn, Sm, and Cu.   The light emitting device according to claim 4, wherein at least one element selected from the group consisting of the rare earth metal element and the transition metal element is Cr.   The minimum reflectance (%) between wavelengths 350 to 700 nm of phosphors emitting in the infrared region is lower than the minimum reflectance (%) between wavelengths 700 to 800 nm, and the difference is 20 The light emitting device according to claim 1, wherein the light emitting device is at least%.   The light emitting device according to any one of claims 1 to 6, wherein an emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting element is between a wavelength of 300 and 700 nm. It contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm, Phosphor.
(M1 _ab M2 _b ) ₃ (M3 _cd M4 _d ) ₅ O ₁₂ (1-2)
However,
M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 represents one or more rare earth metal elements (excluding Sc) different from M1 as the rare earth metal element, in which Tm is essential.
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr and Mn,
O represents oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.   The phosphor according to claim 8, wherein the crystal phase is a crystal phase having a garnet structure. It contains a crystal phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm, Phosphor.
(A1 _1-a A2 _a ) ₂ (A3 _1-b A4 _b ) ₂ O ₆ (2-1)
However,
A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than Tm and alkaline earth metal elements other than Mg;
A2 represents one or more metal elements different from A1 as the rare earth metal element, which essentially requires Tm or Nd,
A3 represents one or more metal elements selected from Mg, Co, and Zn,
A4 is one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu, which must contain Cr or Mn, and B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, And two or more metal elements, including one or more metal elements selected from Hf,
O represents oxygen,
0 <a ≦ 0.5 and 0 <b ≦ 0.75.   The phosphor according to claim 10, wherein the crystal phase is a crystal phase having a double perovskite structure.   The phosphor according to claim 10 or 11, wherein in the formula (2-1), A4 is two or more metal elements containing Mn and Ge. It contains a crystal phase having a chemical composition represented by the following formula (3-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 1000 nm. Phosphor.
_{(D1 1-a-b D2} a D3 b) (D4 1-a D5 11 + a-c D6 c) O 19 ··· (3-1)
However,
D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc);
D2 represents one or more metal elements selected from Ca, Sr, and Ba;
D3 represents one or more rare earth metal elements (excluding Sc) different from D1 as the rare earth metal element, which requires Tm.
D4 contains one or more metal elements selected from Mg and Zn,
D5 represents one or more metal elements selected from Al, Ga, In, and Sc;
D6 represents one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu,
O represents oxygen,
0 ≦ a ≦ 0.99, 0 <b ≦ 0.2, 0 <c ≦ 2.2.   The phosphor according to claim 13, wherein the crystal phase is a crystal phase having a magnetplumbite structure.   The phosphor according to claim 13 or 14, wherein in the formula (3-1), D6 contains at least Cr. It contains a crystal phase having a chemical composition represented by the following formula (4-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 700 and 1000 nm, Phosphor.
E1 ₅ (E2 _1-a E3 _a ) ₄ O ₁₅ (4-1)
However,
E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of Ca, Sr, and Ba;
E2 represents one or more metal elements selected from Al, Ga, In, Sc, Y, Ti, Zr, Si, Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W;
E3 represents one or more metal elements different from E2 selected from transition metal elements,
O represents oxygen,
0 <a <0.2.   The phosphor according to claim 16, wherein the crystal phase is a crystal phase having a hexagonal perovskite structure.   The phosphor according to claim 16 or 17, wherein, in the formula (4-1), E2 contains at least Al.   The phosphor according to any one of claims 16 to 18, wherein, in the formula (4-1), E3 contains at least Cr.   Contains a crystal phase having divalent samarium (Sm) and trivalent thulium (Tm) as the activation elements in the host crystal, absorbs ultraviolet light or visible light, and emits light in the wavelength range from 800 to 1000 nm A phosphor having a peak wavelength. The host crystal is
One or more metal elements selected from the group consisting of alkali metal elements and alkaline earth metal elements,
One or more metal elements selected from B, Al, Ga, Si, Ge, and P, and
The phosphor according to claim 20, further comprising one or more elements selected from O, F, Cl, and Br. The phosphor according to claim 20 or 21, wherein the host crystal contains a crystal phase having a chemical composition represented by the following formula (5-1).
G1 _1-a G2 _a G3 _b O ₅ (5-1)
However,
G1 represents one or more metal elements selected from alkaline earth metal elements,
G2 represents two or more metal elements selected from rare earth metal elements that require Sm and Tm,
G3 represents two or more metal elements selected from B, Al, Ga, Si, Ge and P;
O represents oxygen,
0 <a <0.2 and 1.5 <b <2.5.