CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application of PCT Application No. PCT/CN2018/105573. This Application claims priority from PCT Application No. PCT/CN2018/105573 filed Sep. 13, 2018, and CN 201810147400.3 filed Feb. 12, 2018, the contents of which are incorporated herein in the entirety by reference.

Some references, which may include patents, patent applications, and various publications, are cited and discussed in the description of the present disclosure. The citation and/or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to the present disclosure described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.

TECHNICAL FIELD

The present invention belongs to the technical field of luminescent materials, particularly relates to a near-infrared luminescent material which can be effectively excited by ultraviolet visible light to emit broadband near-infrared light, and further discloses a light-emitting device prepared from the near-infrared luminescent material.

BACKGROUND

In recent years, with the in-depth study in the near-infrared field (700 nm to 2,500 nm) and the expansion of its application range, especially with the development in the fields of fiber-optic communication, plant lighting, facial recognition, iris recognition, security and protection monitoring, laser radar, digital health, 3D sensing, synergism of solar cells, anti-counterfeiting, etc., there is an urgent need to develop a more efficient and stable near-infrared luminescence technology.

The existing methods of acquiring near-infrared short-wave light mainly include light splitting by infrared chips or halogen lamps. However, an infrared chip used in a conventional near-infrared light-emitting device has problems of low excitation efficiency, high cost, and the like. Since the use of a halogen lamp requires light filtering, most of light will be split, resulting in low use efficiency. Meanwhile, since the halogen lamp generates lots of heat, it cannot be applied to a small device.

In comparison with light splitting by the infrared chips and the halogen lamps, a near-infrared light-emitting device prepared from photoluminescent transition metal or rare-earth metal oxides or electroluminescent organic complexes (Chemistry Letters, 2004, 33: 50-51; Advanced Functional Materials, 2002, 12: 745-751; Academic Annual Meeting of the Chinese Chemical Society, 2016) is relatively higher in luminous efficiency and relatively lower in cost. However, an organic complex luminescent material is characterized by poor thermal stability and poor light stability.

At present, owing to their advantages of excellent thermal stability, stable chemical structures, etc., aluminate and gallate of garnet structures are widely used as base materials of luminescent materials, light can be emitted in different wavebands from green light, yellow light, red light and near-infrared light by adding different activator ions. Yb3+as an activator ion can emit near-infrared light of about 1,000 nm due to its 2F5/2→2F7/2 energy level transition. In the aluminate and gallate base materials, Haohai Yu et al. (Haohai Yu, Kui Wu, Bin Yao, Huaijin Zhang, Zhengping Wang, Jiyang Wang, Yongdong Zhang, Zhiyi Wei, Zhiguo Zhang, Xingyu Zhang, and Minhua Jiang. Growth and Characteristics of Yb-doped Y3Ga5O12Laser Crystal, IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 46, NO. 12, DECEMBER 2010) studied Yb-doped laser crystals in YGG (Yttrium Gallium Garnet) and YAG (Yttrium Aluminum Garnet), and found that the crystals can absorb light of 970 nm and emit light of about 1000 nm. However, the crystals cannot efficiently absorb light to emit light under excitation light sources of ultraviolet light, blue light, red light and the like.

Thus, it is necessary to develop and research an inorganic near-infrared emitting material with high luminous efficiency, simple preparation process and high stability, as well as a light-emitting device prepared from the material, which is of positive significance.

SUMMARY

A technical problem to be solved by the present invention is to provide a luminescent material, which has stable chemical properties and excellent luminescent properties, can be effectively excited by ultraviolet visible light and can efficiently emit near-infrared light.

The other technical problem to be solved by the present invention is to further provide a light-emitting device prepared from the near-infrared luminescent material to solve the problems of poor stability, low luminous efficiency, high preparation cost and the like of a near-infrared chip, a halogen lamp and other near-infrared luminescent materials in the prior art.

To solve the above technical problems, the near-infrared luminescent material provided by the present invention includes an inorganic compound with a chemical formula of RuQvOw:Crx, Yby.

R is at least one of Y, La, Lu, Gd and Tb.

Q is Ga and/or Al.

The parameters u, v, w, x and y meet the following conditions: 2.5≤u≤3.5, 3.5≤v≤5.5, 11.25≤w≤13.25, 0.02≤x≤0.30, and 0.02≤y≤0.30.

Preferably, in the near-infrared luminescent material, Q is Ga.

Preferably, in the near-infrared luminescent material, Q is a combination of Ga and Al. A mole percent of Ga to Al is j, and 80%≤j<100%.

Preferably, in the near-infrared luminescent material, R is Y, Tb or Lu. Or, R is a combination of Y and Tb or a combination of Y and Lu.

Preferably, in the near-infrared luminescent material, R comprises Tb and/or Lu.

More preferably, in the near-infrared luminescent material, the parameters x and y meet the following condition: 0.15≤y/x≤2, preferably, 0.3≤y/x≤1.

More preferably, in the near-infrared luminescent material, the parameters u, v, x and y meet the following condition: 1.2≤(v+x)/(u+y)≤1.65, preferably, 1.45≤(v+x)/(u+y)≤1.60.

Preferably, the near-infrared luminescent material further includes Ba and/or F.

The near-infrared luminescent material provided by the present invention is prepared by the following steps: accurately weighing raw materials, wherein the raw materials include an oxide, a fluoride, a carbonate or a chloride of R, an oxide, a fluoride, a carbonate or a chloride of Q, an oxide, a fluoride or a carbonate of Cr and an oxide, a fluoride or a carbonate of Yb according to a stoichiometric proportion; roasting the weighed raw materials for 2 h to 20 h in an air, nitrogen and/or hydrogen atmosphere at 1,400° C. to 1,500° C. to obtain a roasted product; and performing aftertreatment on the roasted product to obtain a required fluorescent powder. The aftertreatment includes crushing, washing (water washing, weak acid washing or the like), grading, etc.

The near-infrared luminescent material provided by the present invention may be prepared by a method in the prior art or a new method to be discovered in the future.

The near-infrared luminescent material provided by the present invention has a peak-peak intensity A in an emission spectrum within the range of 900 nm to 1,100 nm, and a peak-peak intensity B in an emission spectrum within the range of 700 nm to 750 nm, wherein 0.95≤A/(A+B)≤0.99.

The present invention further discloses use of the near-infrared luminescent material for preparation of a light-emitting device.

The near-infrared luminescent material provided by the present invention can be configured to prepare the light-emitting device. The light-emitting device prepared from the near-infrared luminescent material can be used in the fields of fiber-optic communication, plant lighting, facial recognition, iris recognition, security and protection monitoring, anti-counterfeiting, laser radar, food detection, digital health, 3D sensing, synergism of solar cells, etc.

The present invention further discloses a light-emitting device, including a phosphor and an excitation light source. The phosphor includes the near-infrared luminescent material described above.

In particular, the light-emitting device includes a semiconductor chip, a light conversion portion I and a light conversion portion II. The light conversion portion I absorbs primary light emitted by the semiconductor chip and converts the absorbed primary light into secondary light with a larger wavelength. The light conversion portion II absorbs the primary light from the semiconductor chip and the secondary light emitted by the light conversion portion I and converts the absorbed light into thrice light with a larger wavelength.

The light conversion portion I at least includes a luminescent material I. The light conversion portion II at least includes the near-infrared luminescent material.

More preferably, under excitation of the semiconductor chip, the luminescent material I is capable of emitting light with a peak wavelength of 580 nm to 650 nm.

More preferably, the luminescent material I is one or two of luminescent materials with the following general formulas: MmAlaSibNc:Eudand MeSifNg:Eun.

M is selected from Ca and/or Sr.

The parameters m, a, b, c, d, e, f, g and n meet the following conditions: 0.8≤m≤1.2, 0.8≤a≤1.2, 0.8≤b≤1.2, 2≤c≤4, 0.0001≤d≤0.1, 1.8≤e≤2.2, 4≤f≤6, 7≤g≤9, and 0.0001≤n≤0.1.

More preferably, the luminescent material I adopts a crystal structure as CaAlSiN3or Sr2Si5N8.

More preferably, in the luminescent material I, M is a combination of Ca and Sr. A mole percent of Sr to M is z, and 80%≤z<100%.

The luminescent material I provided by the present invention may be prepared by a method in the prior art or a new method to be discovered in the future.

Preferably, in the light-emitting device, the light conversion portion I only includes a luminescent material I.

Preferably, in the light-emitting device, the light conversion portion II only includes the near-infrared luminescent material.

Since the luminescent material I and the near-infrared luminescent material are used simultaneously, the light-emitting device has a broader infrared emission spectrum and a unique function.

As a preferred solution, the semiconductor chip has an emission peak wavelength range of 350 nm to 500 nm and/or 550 nm to 700 nm, preferably 430 nm to 465 nm.

The near-infrared luminescent material provided by the present invention includes the inorganic compound with the chemical formula of RuQvOw:Crx, Yby, has an excitation wavelength of 300 nm to 700 nm and can perform efficient emission (900 nm to 1,100 nm) in a near-infrared region. With a relatively wider excitation wavelength, the near-infrared luminescent material can efficiently absorb ultraviolet-visible light. Compared with a near-infrared organic luminescent material and other system inorganic luminescent materials, the near-infrared luminescent material can emit near-infrared light more strongly. Moreover, the near-infrared luminescent material has excellent thermal resistance, water resistance and light stability, is simple in preparation process and relatively lower in cost, and thus, is an ideal application material for a near-infrared device.

With the application of the technical solution provided by the present invention, the light-emitting device described above can obtain near-infrared light under excitation of different blue light, near ultraviolet light and red light. It not only can be applied to the fields of near fiber-optic communication, plant lighting, facial recognition, iris recognition, security and protection monitoring, anti-counterfeiting, laser radar, food detection, digital health, 3D sensing, synergism of solar cells, etc., but also avoids the defects of other near-infrared acquisition modes. The light-emitting device provided by the present invention is high in luminous efficiency and low in cost, and is applicable to various devices.

