RED LIGHT AND NEAR-INFRARED LIGHT-EMITTING MATERIAL, PREPARATION METHOD THEREOF AND LIGHT-EMITTING DEVICE

Abstract

Disclosed are a red light and near-infrared light-emitting material and a preparation method thereof, and a light-emitting device including the light-emitting material. The red light and near-infrared light-emitting material contains a compound represented by a molecular formula, aSc.sub.2O.sub.3.Ga.sub.2O.sub.3.bR.sub.2O.sub.3, wherein the element R includes one or two of Cr, Ni, Fe, Yb, Nd or Er; 0.001≤a≤0.6; and 0.001≤b≤0.1. The light-emitting material can be excited by a spectrum having a wide wavelength range (ultraviolet light or purple light or blue light) to emit light with a wide spectrum of 650 nm to 1700 nm or multiple spectra, thus having higher light-emitting intensity.

Claims

1. A red light and near-infrared light-emitting material, containing a compound represented by a molecular formula, aSc.sub.2O.sub.3.Ga.sub.2O.sub.3.bR.sub.2O.sub.3, wherein the element R comprises one or two of Cr, Ni, Fe, Yb, Nd or Er; 0.001≤a≤0.6; and 0.001≤b≤0.1.

2. The red light and near-infrared light-emitting material according to claim 1, wherein the compound has a crystal structure which is the same as β-Ga.sub.2O.sub.3.

3. The red light and near-infrared light-emitting material according to claim 2, wherein, 0.15≤a≤0.35, and 0.02≤b≤0.05.

4. The red light and near-infrared light-emitting material according to claim 1, wherein the element R comprises Cr.

5. The red light and near-infrared light-emitting material according to claim 4, wherein the element R is Cr.

6. The red light and near-infrared light-emitting material according to claim 1, wherein the element R further comprises one or two of Ce, Eu, Tb, Bi, Dy and Pr.

7. A preparation method of the red light and near-infrared light-emitting material according to claim 1, comprising: weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula; placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1200° C. to 1600° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen; cooling in the furnace to room temperature to obtain a sintered sample; and ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

8. A light-emitting device, at least comprising an excitation light source and a light-emitting material, wherein the light-emitting material at least comprises the red light and near-infrared light-emitting material according to claim 1.

9. The light-emitting device according to claim 8, wherein peak luminous wavelengths of the excitation light source range from 250 nm to 320 nm, from 400 nm to 500 nm, and from 550 nm to 700 nm.

10. The light-emitting device according to claim 9, wherein the peak luminous wavelength of the excitation light source ranges from 440 nm to 470 nm.

11. The red light and near-infrared light-emitting material according to claim 2, wherein the element R comprises Cr.

12. The red light and near-infrared light-emitting material according to claim 3, wherein the element R comprises Cr.

13. The red light and near-infrared light-emitting material according to claim 2, wherein the element R further comprises one or two of Ce, Eu, Tb, Bi, Dy and Pr.

14. The red light and near-infrared light-emitting material according to claim 3, wherein the element R further comprises one or two of Ce, Eu, Tb, Bi, Dy and Pr.

15. The red light and near-infrared light-emitting material according to claim 4, wherein the element R further comprises one or two of Ce, Eu, Tb, Bi, Dy and Pr.

16. The red light and near-infrared light-emitting material according to claim 5, wherein the element R further comprises one or two of Ce, Eu, Tb, Bi, Dy and Pr.

17. A preparation method of the red light and near-infrared light-emitting material according to claim 2, comprising: weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula; placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1200° C. to 1600° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen; cooling in the furnace to room temperature to obtain a sintered sample; and ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

18. A preparation method of the red light and near-infrared light-emitting material according to claim 3, comprising: weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula; placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1200° C. to 1600° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen; cooling in the furnace to room temperature to obtain a sintered sample; and ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

19. A preparation method of the red light and near-infrared light-emitting material according to claim 4, comprising: weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula; placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1200° C. to 1600° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen; cooling in the furnace to room temperature to obtain a sintered sample; and ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

20. A preparation method of the red light and near-infrared light-emitting material according to claim 5, comprising: weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula; placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1200° C. to 1600° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen; cooling in the furnace to room temperature to obtain a sintered sample; and ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows an XRD diffraction pattern of a light-emitting material obtained in Embodiment 1 of the present invention;

[0026] FIG. 2 shows an excitation emission spectrum of the light-emitting material obtained in Embodiment 1 of the present invention; and

[0027] FIG. 3 shows an excitation emission spectrum of the light-emitting material obtained in Embodiment 2 of the present invention.

DETAILED DESCRIPTION

[0028] For clearer description of the objectives, technical solutions, and advantages of the present invention, the present invention will be further described in detail below in combination with specific implementations and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts in the present invention.

[0029] A first aspect of the present invention provides a red light and a near-infrared light-emitting material, which includes a compound represented by a molecular formula, aSc.sub.2O.sub.3.Ga.sub.2O.sub.3.bR.sub.2O.sub.3, wherein the element R includes one or two of Cr, Ni, Fe, Yb, Nd or Er; 0.001≤a≤0.6; and 0.001≤b≤0.1.

[0030] Preferably, the compound, aSc.sub.2O.sub.3 Ga.sub.2O.sub.3 bR.sub.2O.sub.3, has a crystal structure which is the same as β-Ga.sub.2O.sub.3. Ga.sub.2O.sub.3 has five isomers such as α, β, and γ. Among them, β-Ga.sub.2O.sub.3 is the most stable, has a monoclinic crystal structure, and has the characteristics of stable chemical properties and easy doping of cations. In the present invention, β-Ga.sub.2O.sub.3 may emit red light and near-infrared light by introducing transition metal or rare earth metal ions. In addition, the spectrum can be adjusted and controlled by a substitution of other congeners.

[0031] Preferably, for the red light and near-infrared light-emitting material, further value ranges of a and b meet the following conditions: 0.15≤a≤0.35, and 0.02≤b≤0.05.

[0032] The red light and near-infrared light-emitting material of the present invention is characterized in that β-Ga.sub.2O.sub.3 is doped with Sc which has a larger atomic radius and replaces a Ga cation, so that lattices of β-Ga.sub.2O.sub.3 expand, and the length of a bond between an ion in a luminescent center and an O anion increases. Thus, the crystal field intensity is weakened or the crystal field is split for wide-spectrum or multi-spectrum emission of Cr ions. With the increase in content of Sc ions, movement of long waves in the spectrum is realized. When the content of Sc.sub.2O.sub.3, a, meets the condition: 0.15≤a≤0.35, the light-emitting material of the present invention is of a β-Ga.sub.2O.sub.3 structure, and has a higher luminescent intensity. When a is less than 0.15, the luminescent intensity is slightly lower; and when a exceeds 0.35, it is possible to generate an impurity phase. When the element R in R.sub.2O.sub.3 serves as a luminescent center and the composition meets the condition: 0.02≤b≤0.05, the light-emitting material of the present invention has an optimal luminescent intensity. In the case of b<0.02, the luminescent intensity is low because there are too few luminescent centers. In the case of b>0.05, the concentration of the luminescent centers is too high, which will cause concentration quenching, thus also reducing the luminescent intensity. Preferably, for the red light and near-infrared light-emitting material, the element R includes Cr.

[0033] Preferably, for the red light and near-infrared light-emitting material, the element R is Cr. The transition metal ion Cr.sup.3+ has a radius similar to that of Ga.sup.3+, and is thus easily doped into a distorted octahedral structure of Ga.sup.3+. In addition, the energy level of Cr.sup.3+ may decrease as the strength of the crystal field weakens, which enables the movement of the long waves in the spectrum and wide-peak emission, thereby emitting light with a near-infrared wide spectrum.

[0034] Preferably, the red light and near-infrared light-emitting material further includes one or two of Ce, Eu, Tb, Bi, Dy and Pr. The introduction of one or two of Ce, Eu, Tb, Bi, Dy, and Pr can cause an energy transfer of such element or elements to the element R in the luminescent center to obtain more intensive red light and near-infrared light.

[0035] A second aspect of the present invention provides a preparation method of the aforementioned red light and near-infrared light-emitting material, the method including:

[0036] weighing raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and R.sub.2O.sub.3 according to stoichiometric ratios of molecular formula;

[0037] placing the aforementioned raw materials into a crucible after grinding and evenly mixing, and sintering the raw materials in a high-temperature furnace at a temperature of 1300° C. to 1500° C. for 2 hours to 10 hours under a protective atmosphere of air or nitrogen;

[0038] cooling in the furnace to room temperature to obtain a sintered sample; and

[0039] ball-milling, water-washing and sieving the sample to obtain the red light and near-infrared light-emitting material.

[0040] A third aspect of the present invention provides a light-emitting device which can be manufactured with the aforementioned red light and near-infrared light-emitting material in combination with an excitation light source. Preferably, for the light-emitting device, a peak luminous wavelength of the excitation light source range from 250 nm to 320 nm, from 400 nm to 500 nm, or from 550 nm to 700 nm, preferably from 440 nm to 470 nm.

[0041] In order to further explain the present invention, the red light and near-infrared light-emitting material and the preparation method thereof provided by the present invention will be described in detail below in combination with the embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical solutions of the present invention. The detailed implementations and specific operation procedures are provided to further explain the features and advantages of the present invention, but not to limit the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments.

[0042] The devices and reagents used in the following embodiments are commercially available.

COMPARATIVE EXAMPLE

[0043] According to a stoichiometric ratio of a chemical formula, Sc.sub.0.98BO.sub.3:0.02Cr, raw materials Sc.sub.2O.sub.3, H.sub.3BO.sub.3 and Cr.sub.2O.sub.3 are accurately weighed and evenly mixed to obtain a mixture. The obtained mixture is sintered at 1300° C. for 8 hours in an air atmosphere, and cooled to obtain a sintered product; the sintered product is subjected to post-processing, such as sieving and water-washing, to obtain a near-infrared light-emitting material sample.

[0044] A 460-nm excitation test is performed on the obtained near-infrared light-emitting material sample to obtain the results that an emission peak of the comparative example is at 810 nm and that a half-peak width is 133 nm. The relative luminescent intensity is set to be 100.

Embodiment 1

[0045] According to a stoichiometric ratio of a chemical formula, 0.22Sc.sub.2O.sub.3.Ga.sub.2O.sub.3.0.04Cr.sub.2O.sub.3, raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and Cr.sub.2O.sub.3 are accurately weighed. And then, the raw materials are ground and mixed evenly and placed into a crucible. The raw materials are sintered in a high-temperature furnace at 1450° C. for 8 hours in an air atmosphere and cooled to room temperature in the furnace to obtain a sample. After the sample is ball-milled, washed with water and sieved, the red light and near-infrared light-emitting material of Embodiment 1 is obtained. An X-ray diffraction is used to analyze the light-emitting material obtained in Embodiment 1, so as to obtain an X-ray diffraction pattern of the light-emitting material. As shown in FIG. 1, the diffraction pattern is the same as that of β-Ga.sub.2O.sub.3 shown on PDF Card No. 11-0370, except that the overall diffraction peak is shifted slightly to a small angle, indicating that the light-emitting material in Embodiment 1 is of a β-Ga.sub.2O.sub.3 structure. With the introduction of Sc, a solid solution of β-Ga.sub.2O.sub.3 doped with Sc is obtained, with lattices thereof expanding and the space between lattice planes increasing.

[0046] The light-emitting material obtained in Embodiment 1 is analyzed with a fluorescence spectrometer, and is excited by blue light at 460 nm to obtain a luminescent spectrum. The material can emit red light and near-infrared light with a wide spectrum of 650 nm to 1050 nm under the excitation of the blue light, with a peak wavelength being 798 nm and a half-peak width being 141 nm. The excitation spectrum of the material is obtained by monitoring the light emission at 798 nm, as shown in FIG. 2. It can be seen that the light-emitting material can be effectively excited by ultraviolet light, purple light, blue light and red light, and emit red light and near-infrared light with a wide spectrum. The relative luminescent intensity of the light-emitting material is 309.

Embodiment 2

[0047] According to a stoichiometric ratio of a chemical formula, 0.001Sc.sub.2O.sub.3.Ga.sub.2O.sub.3.0.04Cr.sub.2O.sub.3, raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and Cr.sub.2O.sub.3 are accurately weighed. And then, the raw materials are ground and mixed evenly and placed into a crucible. The raw materials are sintered in a high-temperature furnace at 1490° C. for 8 hours in an air atmosphere and cooled to room temperature in the furnace to obtain a sample. After the sample is ball-milled, washed with water and sieved, the red light and near-infrared light-emitting material of Embodiment 2 is obtained.

[0048] The light-emitting material obtained in Embodiment 2 is analyzed with a fluorescence spectrometer, and excited by blue light at 460 nm to obtain a luminescent spectrum. The material can emit red light and near-infrared light with a wide spectrum of 650 nm to 900 nm under the excitation of the blue light, with a peak wavelength being 734 nm and a half-peak width being 121 nm. An excitation spectrum of the material is obtained by monitoring the light emission at 734 nm, as shown in FIG. 3. It can be seen that the light-emitting material can be effectively excited by ultraviolet light, purple light, blue light and red light, and emit red light and near-infrared light with a wide spectrum. The relative luminescent intensity of the material is 245.

Embodiment 3

[0049] According to a stoichiometric ratio of a chemical formula, 0.6Sc.sub.2O.sub.3.Ga.sub.2O.sub.3.0.04Cr.sub.2O.sub.3, raw materials Sc.sub.2O.sub.3, Ga.sub.2O.sub.3 and Cr.sub.2O.sub.3 are accurately weighed. And then, the raw materials are ground and mixed evenly and placed into a crucible. The raw materials are sintered in a high-temperature furnace at 1600° C. for 8 hours in an air atmosphere and cooled to room temperature in the furnace. After the sample is ball-milled, washed with water and sieved, the red light and near-infrared light-emitting material of Embodiment 3 is obtained.

[0050] The light-emitting material obtained in Embodiment 3 is analyzed with a fluorescence spectrometer, and excited by blue light at 460 nm to obtain a luminescent spectrum. The material can emit red light and near-infrared light with a wide spectrum of 700 nm to 1050 nm under the excitation of blue light, with a peak wavelength being 830 nm and a half-peak width being 143 nm. The relative luminescent intensity of the material is 258.

[0051] For the red light and near-infrared light-emitting materials described in Embodiments 4 to 22, the chemical formulas of the compounds are listed in Table 1 below. The preparation method of the material in each of other embodiments is the same as that in Embodiment 1: the compounds with appropriate stoichiometric ratios are selected just according to the composition of chemical formulas of the target compound in each embodiment to be mixed, ground and sintered under appropriate conditions to obtain the desired near-infrared light-emitting material.

[0052] The performances of the light-emitting materials prepared in various embodiment and in the comparative example are tested. The light-emitting properties in test results of the comparative example and Embodiments 1 to 22 excited at 460 nm are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Peak Half-peak Relative position width luminescent No. Molecular formula/Material (nm) (nm) intensity Comparative Sc.sub.0.98BO.sub.3:0.02Cr 810 133 100 example Embodiment 1 0.22Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 798 141 309 Embodiment 2 0.001Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 734 121 245 Embodiment 3 0.6Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 830 143 258 Embodiment 4 0.3Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.001Cr.sub.2O.sub.3 816 130 167 Embodiment 5 0.3Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.1Cr.sub.2O.sub.3 816 130 186 Embodiment 6 0.15Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 775 140 264 Embodiment 7 0.35Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 808 139 278 Embodiment 8 0.23Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.30.04Yb.sub.2O.sub.3 802, 1000 33 112 (1000 nm) (1000 nm) Embodiment 9 0.23Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.30.04Nd.sub.2O.sub.3 802, 1000 35 114 (1000 nm) (1000 nm) Embodiment 10 0.23Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.30.04Er.sub.2O.sub.3 803, 1550 33 116 (1550 nm) (1550 nm) Embodiment 11 0.25Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.01Cr.sub.2O.sub.3 809 142 305 Embodiment 12 0.22Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.02Cr.sub.2O.sub.3 805 143 303 Embodiment 13 0.22Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 805 141 300 Embodiment 14 0.4Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.04Cr.sub.2O.sub.3 826 140 256 Embodiment 15 0.5Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.03Cr.sub.2O.sub.3 826 142 286 Embodiment 16 0.1Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.03Cr.sub.2O.sub.3 792 143 306 Embodiment 17 0.2Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.06Cr.sub.2O.sub.3 796 143 305 Embodiment 18 0.2Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.08Cr.sub.2O.sub.3 796 139 304 Embodiment 19 0.01Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 740 143 305 Embodiment 20 0.04Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 746 142 304 Embodiment 21 0.08Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 750 143 304 Embodiment 21 0.12Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 758 142 304 Embodiment 22 0.16Sc.sub.2O.sub.3•Ga.sub.2O.sub.3•0.05Cr.sub.2O.sub.3 775 143 304

[0053] It can be seen from the above table that the light-emitting material of the present invention has the characteristics of wide-spectrum emission or multi-spectrum emission of red light and near-infrared light under the excitation of blue light. Compared with the existing near-infrared light-emitting material in the comparative example, the red light and near-infrared light-emitting material of the present invention has a higher luminescent intensity.

[0054] In summary, the present invention provides a red light and near-infrared light-emitting material and a preparation method thereof, and a light-emitting device including the light-emitting material. The red light and near-infrared light-emitting material contains a compound represented by a molecular formula, aSc.sub.2O.sub.3.Ga.sub.2O.sub.3.bR.sub.2O.sub.3, wherein the element R includes one or two of Cr, Ni, Fe, Yb, Nd or Er; 0.001≤a≤0.6; and 0.001≤b≤0.1. The light-emitting material can be excited by a spectrum with a wide range of wavelengths (ultraviolet light or purple light or blue light) to emit light with a wide spectrum of 650 nm to 1700 nm or multiple spectra, thus having a higher light-emitting intensity.

[0055] It should be understood that the foregoing specific embodiments of the present invention are only used as examples to illustrate or explain the principles of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent substitutions or improvements that are made within the spirit and scope of the present invention should all be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.