A near-infrared fluorescent powder and an optical device

Abstract

The application discloses a near-infrared fluorescent powder and a light-emitting device. The near-infrared fluorescent powder comprises a composition formula LiA a Sc 1‑a‑p‑d‑ c D d P p An inorganic compound of EO4:cCr, wherein A elements include one or two of Li, Na and K, D elements include two of Ga, In, Al, Ce and Bi, and E elements include two or three of Hf, Ge and Si; wherein 0

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, and in particular to a near-infrared phosphor and optical device. Background Technology

[0002] In recent years, the application of near-infrared excitation sources in information detection fields such as medical / food testing, water quality testing, component analysis, and semiconductor material detection has become a focus of the industry. Currently, the mature methods for realizing near-infrared light emission mainly rely on photoluminescent near-infrared semiconductor chips. However, near-infrared chips suffer from narrow spectra (half-width at half maximum < 40nm) and poor tunability. For example, in applications requiring broadband, such as water quality testing, continuous spectral coverage of the 400nm-1100nm emission band is mainly used. Near-infrared chips with multiple emission bands are complex and uncontrollable, resulting in high implementation difficulty and cost. The driving current of near-infrared LED chips with different emission bands varies greatly, and large differences in light decay between different chips can easily lead to a sharp drop in thermal stability, affecting the lifespan of the entire light-emitting device. Furthermore, the discontinuous spectrum significantly increases the difficulty of backend detection calculations. In addition, the technology for long-wavelength chips (>1000nm) is currently immature, difficult to implement, and has low luminous efficiency, limiting the application and promotion of near-infrared LED optical devices.

[0003] Fluorescent-conversion near-infrared LEDs are an emerging type of near-infrared excitation light source. They are implemented using a packaging method of "blue / visible light chip + high-efficiency near-infrared phosphor," which avoids the shortcomings of chip technology and has advantages such as simple fabrication process, low cost, and tunable spectrum, thus attracting widespread attention in the industry. As one of the core materials of fluorescent-conversion near-infrared LEDs, near-infrared phosphors directly determine the luminous efficiency, spectral continuity, and other performance characteristics of near-infrared LED devices, as well as their application scenarios. However, research on near-infrared phosphors is still in its early stages, with a lack of material types, limited spectral coverage, and low luminous efficiency. In particular, there is a lack of high-efficiency near-infrared phosphors with emission peak wavelengths in the 1080nm-1130nm band. Summary of the Invention

[0004] The purpose of this invention is to provide a near-infrared phosphor and an optical device. By proposing a near-infrared phosphor that can be excited by blue and red light, especially one that can be matched with a blue light chip, and the emission peak position of the near-infrared phosphor is located in the range of 1080nm-1130nm, by using non-equivalent ion pair substitution to cause appropriate lattice distortion, the forbidden transition law of Cr in the luminescence center is broken, the radiation transition efficiency is improved, and the luminescence efficiency is greatly improved.

[0005] To address the aforementioned technical problems, a first aspect of this invention provides a near-infrared phosphor, wherein the near-infrared phosphor comprises a compound with the formula LiA.

[0017] Sc 1-a-p-d-c D d P p An inorganic compound of EO4:cCr, the A element includes one or two of Li, Na, and K, the D element includes two of Ga, In, Al, Ce, and Bi, and the E element includes two or three of Hf, Ge, and Si;

[0006] Where 0 < a ≤ 0.15, 0 < d ≤ 0.2, 0 < p ≤ 0.15, 0 < c ≤ 0.02.

[0007] Furthermore, a = p.

[0008] Furthermore, the A element must contain Li, and the molar percentage of Li in the A element is i, 0% < i ≤ 40%, preferably 15% < i ≤ 40%.

[0009] Furthermore, the D element must contain In, and the molar percentage of In in the D element is j, 0% < j ≤ 60%, preferably 20% ≤ j ≤ 55%.

[0010] Furthermore, the D element is Ce and Bi, and the molar percentage of Ce in the D element is k, 0% < k ≤ 35%, preferably 10% < k ≤ 30%.

[0011] Furthermore, the E element must contain Ge, and the molar percentage of Ge in the E element is m, 0% < m ≤ 90%, preferably 50% < m ≤ 90%.

[0012] Furthermore, the E element contains Hf, Ge, and Si, the molar percentage of Ge in the E element is n, 40% ≤ n ≤ 90%, and the molar ratio of Hf and Si < 1.

[0013] Correspondingly, the second aspect of the embodiments of the present invention provides a light-emitting device, comprising an excitation light source and a luminescent material, and the luminescent material comprises any one of the above-mentioned near-infrared phosphors.

[0014] Furthermore, the excitation light source is a semiconductor chip with an emission peak wavelength range of 400 nm - 460 nm or 600 nm - 660 nm;

[0015] The luminescent material further comprises a visible light phosphor with an emission wavelength range of 500 nm - 780 nm and a near-infrared phosphor with an emission wavelength range of 780 nm - 1550 nm.

[0016] Furthermore, the chemical formula of the visible light phosphor with an emission wavelength range of 500 nm - 780 nm is (Ca,Sr)AlSiN3:Eu.

[0017] The above technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0018] 1. By including equal proportions of Li and P in inorganic compounds and using non-equivalent ion pairs for substitution, appropriate lattice distortion is created, breaking the forbidden transition law of the luminescent center Cr, improving the radiation transition efficiency, and significantly increasing the luminescence efficiency.

[0019] 2. In addition to the absorption of the near-infrared phosphor in the red light region, the use of (CaSr)AlSiN3:Eu red phosphor with an emission wavelength range of 620nm-660nm further enhances the near-infrared emission efficiency (photoelectric conversion efficiency in the near-infrared band) and provides a unique spectrum for the aforementioned applications. Attached Figure Description

[0020] Figure 1 This is the absorption spectrum of the near-infrared phosphor sample provided in the embodiments of the present invention;

[0021] Figure 2 This is the emission spectrum of the near-infrared phosphor sample provided in the embodiments of the present invention;

[0022] Figure 3 This is the XRD pattern of the near-infrared phosphor sample provided in the embodiments of the present invention;

[0023] Figure 4 This is a schematic diagram of the light-emitting device structure provided in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] Please refer to Figure 1 The first aspect of the present invention provides a near-infrared phosphor, the near-infrared phosphor comprising the formula LiA a Sc 1-a-p-d-c D d P p EO4:cCr is an inorganic compound, where element A includes one or two of Li, Na, and K; element D includes two of Ga, In, Al, Ce, and Bi; and element E includes two or three of Hf, Ge, and Si; 0 <a≤0.15,0<d≤0.2,0<p≤0.15,0<c≤0.02。

[0026] The following theoretical explanations are all based on the premise of having a phosphor crystal structure.

[0027] In the present invention, P elements are contained in the Sc lattice sites. P is a reactive element relative to Sc, which is beneficial to the further nucleation and grain growth of the phosphor, and improves the luminescence intensity. At the same time, the entry of P elements into the Sc element positions causes lattice distortion, which is beneficial to breaking the forbidden transition of the luminescence center Cr 3+ of the forbidden transition, resulting in enhanced absorption and improved light efficiency of the material. According to experimental studies, when the content of P elements is too low, the improvement effect of P elements on the phosphor is not obvious and the luminescence intensity is low. When the content of P elements is too high, it may lead to the generation of impurities and significant lattice distortion, resulting in an increase in the non-radiative transition probability of the phosphor and a low luminescence intensity as well. Therefore, it is preferred that 0 < p ≤ 0.15.

[0028] Preferably, in the inorganic compound of LiA a Sc 1-a-p-d-c D d P p EO4:cCr, a = p.

[0029] Element A is one or two of Li, Na, and K. A is a reactive element, which is beneficial to the further nucleation and grain growth of the phosphor and improves the luminescence intensity. On the other hand, the simultaneous entry of element A and P elements into the Sc element positions is beneficial to compensating for the charge imbalance caused by the entry of P elements into the Sc elements, preventing the generation of too many vacancies, and is beneficial to improving the light efficiency of the material.

[0030] When the content of element A is too low, the improvement effect of element A on the phosphor is not obvious and the luminescence intensity is low. When the content of element A is too high, it may lead to the generation of too many vacancies, resulting in an increase in the non-radiative transition probability of the phosphor and a low luminescence intensity as well. Therefore, it is preferred that 0 < a ≤ 0.15, and when a = p, the charge compensation effect of element A and P elements reaches the best, which is beneficial to improving the luminescence efficiency.

[0031] The above inorganic compound contains equal proportions of Li and P. Using non-equivalent ion pair substitution causes appropriate lattice distortion, breaks the forbidden transition law of the luminescence center Cr, improves the radiation transition efficiency, and greatly improves the luminescence efficiency.

[0032] Specifically, element A must contain Li, and the molar percentage of Li in element A is i, 0% < i ≤ 40%, preferably 15% < i ≤ 40%.

[0033] Element A must contain Li, and the radii and electronegativities of Li and Sc elements are more similar. On the one hand, after co-doping Li with other metal elements, the lattice distortion caused to the material lattice is small. Without causing a large change in the crystal field, that is, when the emission spectrum remains almost unchanged, it is beneficial to further improve the luminescence intensity of the material. On the other hand, the doping of Li element is conducive to the formation of covalent bonds, the increase of covalent bond property, and the improvement of the probability of radiative transition of the luminescence center, that is, the improvement of luminescence intensity.

[0034] When the content of Li element is too low, due to the insignificant improvement effect of Li element on the phosphor, the luminescence intensity is low. When the content of Li element is too high, it may lead to the generation of too many vacancies, resulting in an increase in the non-radiative transition probability of the phosphor and a low luminescence intensity. Therefore, the molar percentage of Li occupying element A is i, which can be selected as 0% < i ≤ 40%, preferably 15% < i ≤ 40%.

[0035] Specifically, element D can be two of Ga, In, Al, Ce, and Bi and enter the Sc lattice site. Different ionic radii and electronegativities of element D will cause changes in the original ligand positions, thereby changing the crystal field strength and the centroid displacement of the luminescence center, and the emission spectrum of the phosphor is likely to shift, which can effectively enrich the emission band of the near-infrared phosphor. And, on the premise of ensuring the pure phase structure, 0 < d ≤ 0.2.

[0036] In a specific embodiment of the present invention, element D must contain In, and the molar percentage of In in element D is j, 0% < j ≤ 60%, preferably 20% ≤ j ≤ 55%. The radius and coordination environment of In are similar to those of Sc, which can cause appropriate lattice distortion without generating impurity phases, break the forbidden transition of the luminescence center Cr 3+ and enhance the radiative transition of the luminescence center and the luminescence intensity; on the other hand, In has a relatively large electronegativity and can form covalent bonds with excellent covalent bond properties with O, enhancing the luminescence intensity.

[0037] In another specific embodiment of the present invention, element D is Ce and Bi, and the molar percentage of Ce in element D is k, 0% < k ≤ 35%, preferably 10% < k ≤ 30%. When element D is Ce and Bi, the absorption spectrum of the matrix doped with Cr alone 3+ covers the visible light band from blue to red. When element D is Ce and Bi, Ce and Bi ions can be doped into the matrix as sensitizers and exhibit yellow-green light emission, and its emission spectrum coincides with the absorption spectrum of Cr 3+ and energy transfer from Ce and Bi ions to Cr 3+ can be carried out to improve Cr 3+Near-infrared luminescence intensity. According to experimental studies, when the contents of Ce and Bi elements are too low, due to the lack of sensitizers, the energy transfer effect is not obvious and the luminescence intensity is low. When the contents of Ce and Bi elements are too high, concentration quenching occurs, resulting in an increase in non-radiative transitions. Further, according to the optimal ratio selection of the activator (luminescence center) and the sensitizer, Bi element has more excellent allowed transition energy levels. Therefore, it is preferred that the molar percentage of Ce occupying the D element is k, where 0% < k ≤ 35%, preferably 10% < k ≤ 30%. At this time, the energy transfer effect is optimal.

[0038] Specifically, the E element must contain Ge, and the molar percentage of Ge in the E element is m, where 0% < m ≤ 90%, preferably 50% < m ≤ 90%. Ge element has excellent semiconductor material properties and a relatively excellent band gap, which is beneficial for the luminescence center to obtain more sufficient radiative transitions.

[0039] Further, the E element contains Hf, Ge, and Si. The molar percentage of Ge in the E element is n, where 40% ≤ n ≤ 90%, and the molar ratio of Hf and Si < 1. Si element has the characteristic of a wide absorption band. When Si is doped, it is expected to increase the band gap of the material, increase the probability of radiative transitions, enhance the light efficiency, and shift the luminescence band to the short wavelength. The radius of Hf element is large, which is easy to expand the matrix lattice of the material, thereby reducing the crystal field strength and shifting the emission band of the phosphor to the long wavelength. And the Hf element has high activity, which is beneficial for nucleation and grain growth, improving the luminescence intensity.

[0040] The above phosphor can preferably be prepared by the following method to prepare a near-infrared phosphor. The above preparation method includes:

[0041] Step 1: Using elemental substances, nitrides, oxides, or their alloys selected from different elements as raw materials, and mixing the raw materials to obtain a mixture.

[0042] Step 2: Putting the mixture obtained in Step 1 into a container and roasting it in a reducing atmosphere to obtain a roasted product. The highest sintering temperature is 1400°C - 1450°C, and the holding time is 2h - 6h.

[0043] Step 3: Sequentially crushing, washing, sieving, and drying the roasted product in Step 2 to obtain the phosphor.

[0044] The absorption spectrum peak wavelength of the phosphor of the inorganic compound with the above composition is located in the 400nm - 550nm and 600nm - 800nm bands, and the emission peak wavelength covers the range of 1080nm - 1130nm.

[0045] In addition, it has absorption in the 680nm - 850nm deep red - near-infrared region, which is suitable for being doped into fiber materials or ink materials for anti-counterfeiting or commemorative coin marking.

[0046] Accordingly, a second aspect of the present invention provides a light-emitting device comprising an excitation light source and a light-emitting material, wherein the light-emitting material comprises any of the aforementioned near-infrared phosphors.

[0047] The light-emitting device employs lower-layer red light conversion, utilizing the red light absorption of this material to improve the photoelectric conversion efficiency of LED near-infrared light. The use of the aforementioned near-infrared phosphor in the light-emitting device can solve the problems of low near-infrared luminous efficiency in existing infrared chip technology, especially the difficulty in realizing chip technology with emission peak wavelengths in the 1080nm-1130nm band, resulting in low luminous efficiency and low light-emitting device efficiency. Furthermore, it can address the shortage of high-efficiency near-infrared phosphor materials with peak wavelengths in the 1080nm-1130nm band.

[0048] Furthermore, the excitation source is a semiconductor chip with an emission peak wavelength range of 400nm-460nm or 600nm-660nm.

[0049] Optionally, the excitation source mentioned above is a semiconductor light-emitting diode (LED) source. Currently, commercial LED excitation sources have an excitation wavelength range within this range, specifically two types of excitation sources. Utilizing LEDs within the aforementioned wavelength range is beneficial for the photoluminescence of phosphors.

[0050] Furthermore, the luminescent material also includes visible light phosphors with an emission wavelength range of 500nm-780nm and near-infrared phosphors with an emission wavelength range of 780nm-1550nm.

[0051] Specifically, to further improve the luminescence effect of the light-emitting device, the phosphor preferably also includes other phosphors, including visible light phosphors with an emission wavelength range of 500nm-780nm and near-infrared phosphors with an emission wavelength range of 780nm-1550nm. The visible light phosphor is a phosphor with an emission wavelength range of 500nm-780nm, including but not limited to (Mg,Zn)(Ca,Sr,Ba)3Si2O8:Eu 2+ (Ca,Sr,Ba)Si2N2O2:Eu 2+ β-SiAlON:Eu 2+ (Lu,Y,Gd)3(Al,Ga)5O 12 :Ce 3+ ,Tb 3+ (Lu,Y,Gd)3(Al,Ga)5O 12 :Ce 3+ (La,Y,Lu)3Si6N 11 :Ce 3+ (Ca,Sr,Ba)2Si5N8:Eu2+ (Ca,Sr)AlSiN3:Eu 2+ K2(Si,Ge)F6:Mn 4+ (Sr,Ca,Ba)4(Al,Sc,Ga,In) 14 O 25 :Mn 4+ (La,Y,Gd,Lu)3(Al,Ga)(Ge,Si)5O 16 :Mn 4+ , CaO·Al2O3·Ga2O3·ZnO·MnO2·Li2O, (Lu,Y,Gd)3(Al,Ga)5O 12 :Mn 4+ One or more of them.

[0052] Near-infrared phosphors are phosphors with emission wavelengths in the range of 780 nm to 1550 nm, including but not limited to (La,Y,Gd,Lu)3(Al,Ga)5(Ge,Si)O. 14 :Cr 3+ ,Yb 3+ Er 3+ , Sc2O3·Ga2O3·(Cr,Yb,Nd,Er)2O3, (La,Lu,Y,Gd)(Sc,Ga,Al,In)3B4O 12 :Cr 3+ ,Yb 3+ Er 3+ One or more of the elements. The comma in each substance indicates that the element within the brackets can be a single component or a solid solution containing more than one element, for example: (Ca,Sr)AlSiN3:Eu 2+ Represented as CaAlSiN3:Eu 2+ SrAlSiN3:Eu 2+ and Ca 1-α Sr α AlSiN3:Eu 2+ One or more of the following solid solutions: (0<α<1).

[0053] Furthermore, the visible light phosphor with a wavelength range of 500nm-780nm has the chemical formula (Ca,Sr)AlSiN3:Eu. In addition to the absorption of this near-infrared phosphor in the red light region, the use of a (Ca,Sr)AlSiN3:Eu red phosphor with an emission wavelength range of 620-660nm further enhances the near-infrared emission efficiency (photoelectric conversion efficiency in the near-infrared band) and provides a unique spectrum tailored to the aforementioned applications.

[0054] By combining the near-infrared phosphor of the present invention with the aforementioned phosphor, the light-emitting device emits light with high luminous efficiency, solving the problems of low luminous efficiency in the long near-infrared range of existing infrared chip technology, especially the difficulty in realizing chip technology with emission peak wavelengths in the 1080nm-1130nm band, low luminous efficiency, and poor emission spectrum continuity of the light-emitting device. This satisfies the application needs of many traditional and emerging fields, including moisture detection, material detection, sweeping machines, and semiconductor material flaw detection.

[0055] The above-mentioned near-infrared phosphor and light-emitting device are described below with reference to several embodiments and comparative examples:

[0056] Example 1

[0057] The near-infrared phosphor provided in this embodiment contains compounds with the formula LiLi 0.01 Sc 0.95 P 0.02 Ge 0.95 Si 0.05 O4:0.02Cr. The oxide raw materials were ground and mixed according to the stoichiometric ratio of the chemical formula to obtain a mixture. The mixture was then calcined at 1400℃ for 5 hours after grinding and mixing. After cooling, the calcined product was obtained. The calcined product was then subjected to post-processing such as crushing, grinding, grading, and sieving to obtain the near-infrared phosphor intermediate.

[0058] The absorption and emission spectra of the obtained near-infrared samples were measured using a fluorescence spectrometer. The absorption and emission spectra of the near-infrared phosphor samples prepared in Example 1 are shown below. Figure 1-2 As shown. From Figure 1-2 It can be seen that the obtained near-infrared phosphor samples have effective absorption in the 400nm-550nm and 600nm-800nm ​​wavelength ranges, and the emission wavelength covers 1080nm-1130nm, with the emission peak located at 1100nm. The results are listed in Table 1.

[0059] Table 1

[0060]

[0061]

[0062]

[0063]

[0064] The material and luminescence performance characterization results of the near-infrared phosphors prepared in Examples 1-57 and the comparative examples are shown in Table 1.

[0065] Note: With the luminous intensity of the comparative example as the baseline value of 100, the relative luminous intensity of the embodiment is its actual luminous intensity divided by the actual luminous intensity of the comparative example, and then multiplied by 100%.

[0066] By comparing the data of each example in Table 1 above, the following conclusions can be drawn: For LiA a Sc 1-a-p-d-c D d P p EO4:cCr inorganic compounds, wherein element A is one or two of Li, Na, and K, which can form structural unit pairs with element P and co-dope into the Sc site to achieve charge balance; element D is two of Ga, In, Al, Ce, and Bi, which enter the Sc site to change the structural symmetry of the material; element E is two or three of Hf, Ge, and Si; all of the above methods can achieve the modulation of the spectral emission peak position in the 1180-1030nm band and the enhancement of luminescence intensity, resulting in more efficient near-infrared broadband emission.

[0067] Through comparison with Example 1 and the comparative examples, it was found that the compound must contain phosphor (P). P is a more reactive element than Sc, which is beneficial to the further nucleation and grain growth of the phosphor. At the same time, the entry of P into the Sc element position causes lattice distortion, which is beneficial to breaking the luminescent center Cr. 3+ The prohibition of transitions leads to enhanced absorption and improved luminous efficacy of the material.

[0068] Comparing Examples 1-3, the doping of the active element A is beneficial for further nucleation and grain growth of the phosphor, thus improving luminescence intensity. On the other hand, when A and P elements simultaneously enter the Sc element positions, and a = p, it helps to compensate for the charge imbalance caused by P entering the Sc element, preventing the generation of too many vacancies and improving the material's luminous efficiency.

[0069] Comparing Examples 4-13, element A necessarily contains Li, and the radius and electronegativity of Li are more similar to those of Sc. On the one hand, the co-doping of Li with other metal elements causes less lattice distortion to the material's crystal lattice. Without causing a significant change in the crystal field (i.e., the emission spectrum remains almost unchanged), this is beneficial for further improving the material's luminescence intensity. On the other hand, Li doping promotes the formation of covalent bonds. Increased covalent bonding increases the probability of radiative transitions at the luminescence center, thus improving luminescence intensity.

[0070] Comparing Examples 13-23, it was found that element D necessarily contains In. The radius and coordination environment of In are similar to those of S and C, which can cause appropriate lattice distortion without generating impurity phases, thus breaking the luminescent center Cr. 3+The forbidden transition of In enhances the transition radiation of the luminescent center and increases the luminescence intensity; on the other hand, In has a large electronegativity and can form a covalent bond with O with excellent covalent bonding, thus increasing the luminescence intensity.

[0071] By comparing Examples 13 and 24-31, we can see that element D can also be Ce or Bi, and the matrix can be doped with Cr alone. 3+ Its absorption spectrum covers the visible light band from blue to red. When the D element is Ce or Bi, Ce and Bi ions can act as sensitizers and dope into the matrix, exhibiting yellow-green light emission, and their emission spectrum is similar to that of Cr. 3+ The absorption spectra overlap, enabling Ce and Bi ions to be converted to Cr. 3+ Energy transfer, improving Cr 3+ Near-infrared luminescence intensity.

[0072] Through comparison of Examples 23, 31, and 32-42, it is found that element E must contain Ge. Element Ge has excellent semiconductor material properties and a relatively good band gap, which is conducive to the luminescent center obtaining more sufficient radiative transitions and improving the luminescence intensity.

[0073] Comparing Examples 34, 38, and 43-54, the element E is one of three elements: Hf, Ge, and Si. Si has a wide absorption band, and when Si is incorporated, it is expected to increase the band gap of the material, increase the probability of radiative transitions, and enhance luminous efficiency; it also causes the emission band to shift to shorter wavelengths. Hf has a large radius, which easily causes the matrix lattice to expand, thereby reducing the crystal field strength and shifting the phosphor emission band to longer wavelengths; moreover, Hf has high reactivity, which is beneficial for nucleation and grain growth, thus improving luminescence intensity.

[0074] The following embodiments are light-emitting devices made using the broadband near-infrared phosphor of the present invention as the light-emitting material. In some embodiments, such as... Figure 4 As shown, adding a layer of white glue between the phosphor and the chip keeps the phosphor away from the high-temperature zone, which helps reduce the performance degradation of the LED chip caused by phosphor decay.

[0075] Example 58

[0076] The light-emitting device described in this embodiment uses a semiconductor chip with a wavelength of 460nm as the light source, and the light-emitting material is a near-infrared phosphor with the chemical formula LiLi. 0.03 K 0.07 Sc 0.608 Ce 0.045 Bi 0.135 P 0.1 Ge 0.85 Hf 0.06 Si 0.09O4:0.012Cr, according to the stoichiometric ratio, the raw materials were accurately weighed and symmetrically ground and mixed to obtain a mixture; the mixture was calcined at 1450℃ for 5 hours, and after cooling, a calcined product was obtained; the obtained calcined product was crushed, ground, graded, sieved and washed to obtain near-infrared phosphor. In addition, in this embodiment, a Y-ray emission wavelength in the range of 500nm-780nm was selected. 0.85 Al5O 12 0.15Ce 3+ And near-infrared phosphors (La,Y,Gd,Lu)3(Al,Ga)5(Ge,Si)O with emission wavelengths in the range of 780nm-1550nm 14 :Cr 3+ ,Yb 3+ Er 3+ The formula is Sc2O3·Ga2O3·(Cr,Yb,Nd,Er)2O3. In this embodiment, firstly, a layer of silicone is coated on top of the chip before applying the phosphor. This is cured to keep the phosphor away from the high-temperature area of ​​the chip, effectively reducing the attenuation of the light source intensity caused by the phosphor being heated. Then, a visible light emitting material is mixed with silicone at a mass ratio of 0.28:1 and uniformly coated onto the silicone. This mixture is then baked to cure into a visible light fluorescent layer. The visible light provided by the visible light emitting material and the visible light absorption by the near-infrared emitting material improve the luminous efficiency of the device, especially the photoelectric conversion efficiency in the near-infrared emission band. Next, the near-infrared emitting material and silicone are mixed uniformly at a mass ratio of 2.2:1, stirred, and degassed to obtain a visible light fluorescent conversion layer mixture. This mixture is then sprayed onto the surface of the visible light emitting material layer, cured, and encapsulated to obtain the desired LED light-emitting device. Using a high-precision, fast spectroradiometer integrating sphere testing system, the light source of the optical device provided in each embodiment was lit with a constant current (forward voltage 3V, forward current 60.0mA). The test results showed that the light-emitting device described in this embodiment has an optical power of 100.1mW and a photoelectric conversion efficiency of 82.3% in the near-infrared band.

[0077] The performance parameters of the optical devices obtained by encapsulating near-infrared luminescent materials in various embodiments of the present invention are shown in Table 2.

[0078] Table 2

[0079]

[0080] As can be seen from Table 2 above, the phosphor in the optical device of the present invention can be effectively excited by LED chips. Through an optical device combining visible light emitting materials and near-infrared emitting materials, dual emission of visible light in the 500nm-780nm band and near-infrared light in the 780nm-1550nm band can be achieved. Furthermore, the device has suitable luminous flux and a continuous or special waveform emission spectrum, making it effective for applications such as moisture detection, material testing, robotic vacuum cleaners, and semiconductor material flaw detection. In addition to the near-infrared phosphor's absorption in the red light region, the optical device also uses a (CaSr)AlSiN3:Eu red phosphor with an emission wavelength range of 620nm-660nm, resulting in more efficient near-infrared emission (photoelectric conversion efficiency in the near-infrared band) and a unique spectrum tailored to the aforementioned applications.

[0081] The embodiments of the present invention aim to protect a near-infrared phosphor and a light-emitting device, and have the following effects:

[0082] 1. By including equal proportions of Li and P in inorganic compounds and using non-equivalent ion pairs for substitution, appropriate lattice distortion is created, breaking the forbidden transition law of the luminescent center Cr, improving the radiation transition efficiency, and significantly increasing the luminescence efficiency.

[0083] 2. In addition to the absorption of the near-infrared phosphor in the red light region, the use of (CaSr)AlSiN3:Eu red phosphor with an emission wavelength range of 620nm-660nm further enhances the near-infrared emission efficiency (photoelectric conversion efficiency in the near-infrared band) and provides a unique spectrum for the aforementioned applications.

[0084] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A near-infrared phosphor, characterized in that, The near-infrared phosphor contains LiA. a Sc 1-a-p-d- c D d P p EO4:cCr is an inorganic compound in which element A is one or two of Li, Na and K, element D is two of Ga, In, Al, Ce and Bi, and element E is two or three of Hf, Ge and Si. Among them, 0 <a≤0.15,0<d≤0.2,0<p≤0.15,0<c≤0.02。 2. The near-infrared phosphor according to claim 1, characterized in that, a=p.

3. The near-infrared phosphor according to claim 2, characterized in that, Element A must contain Li, and the molar percentage of Li in element A is i, 0%. <i≤40%。 4. The near-infrared phosphor according to claim 3, characterized in that, The numerical range of the molar percentage i of Li in element A is 15%. <i≤40%。 5. The near-infrared phosphor according to claim 3, characterized in that, Element D must contain In, and the molar percentage of In in element D is j, 0%. <j≤60%。 6. The near-infrared phosphor according to claim 5, characterized in that, The numerical range of the molar percentage j of In in D is 20% ≤ j ≤ 55%.

7. The near-infrared phosphor according to claim 3, characterized in that, Element D consists of Ce and Bi, with Ce accounting for k moles of 0% of element D. <k≤35%。 8. The near-infrared phosphor according to claim 7, characterized in that, The molar percentage k of Ce in D ranges from 10%. <k≤30%。 9. The near-infrared phosphor according to any one of claims 5-8, characterized in that, Element E must contain Ge, and the molar percentage of Ge in element E is m, 0%. <m≤90%。 10. The near-infrared phosphor according to claim 9, characterized in that, The molar percentage of Ge in element E is 50%. <m≤90%。 11. The near-infrared phosphor according to claim 9, characterized in that, The element E consists of Hf, Ge, and Si, with Ge accounting for n molar percentages of E, where 40% ≤ n ≤ 90%, and the molar ratio of Hf to Si is < 1.

12. A light-emitting device, characterized in that, It includes an excitation light source and a luminescent material, wherein the luminescent material comprises a near-infrared phosphor as described in any one of claims 1-11.

13. The light-emitting device according to claim 12, characterized in that, The excitation source is a semiconductor chip with an emission peak wavelength range of 400 nm - 460 nm or 600 nm - 660 nm; The luminescent material also includes visible phosphors with an emission wavelength range of 500 nm to 780 nm and near-infrared phosphors with an emission wavelength range of 780 nm to 1550 nm.

14. The light-emitting device according to claim 13, characterized in that, The chemical formula of the visible light phosphor in the 500 nm - 780 nm range is (Ca,Sr)AlSiN3:Eu.

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