Blue-light-excited narrow-band double-color fluorescent powder for high-color-gamut display and preparation method thereof

Abstract

The invention discloses blue-light-excited narrow-band double-color fluorescent powder for high-color-gamut display and a preparation method of the blue-light-excited narrow-band double-color fluorescent powder, and belongs to the technical field of luminescent materials. According to the fluorescent powder, high-symmetry hexagonal system aluminate BaZnAl10O17 is used as a matrix, Li < + >, Na < + > and K < + > are introduced as charge compensation agents, and two kinds of active ions Mn < 2 + > and Mn < 4 + > are doped at the same time. Under the excitation of blue light of 440-470 nm, the blue light emitting material can generate width at half maximum of 515-520 nm at the same time; narrow-band green light with the wavelength of 35 nm and the width at half maximum of 660-670 nm; and narrow-band red light with the wavelength of 30 nm is obtained. According to the invention, double-narrow-band emission in a single-matrix material is realized, and the problems of non-uniform luminescence, low efficiency and the like caused by physical mixing of green powder and red powder in the prior art are effectively solved. The fluorescent powder is simple in preparation process, high in color purity, good in thermal stability and high in matching degree with commercial blue light LED chips, and has wide application prospects in the field of high-color-gamut liquid crystal display backlight sources.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a material based on a highly symmetric hexagonal aluminate matrix and simultaneously doped with Mn. 2+ and Mn 4+ A narrowband dual-color phosphor using Li / Na / K for charge compensation is developed. This phosphor can be effectively excited by blue light and is suitable for high color gamut liquid crystal display backlights. Background Technology

[0002] Achieving wide color gamut display is one of the core goals of current display technology development. In LCD backlights, blue LED chips are typically used to excite green and red phosphors to produce white light. The full width at half maximum (FWHM) of the phosphor's emission spectrum directly determines the display's color gamut range. Currently, commercially available green phosphors (such as β-SiAlON:Eu)... 2+ The full width at half maximum (FWHM) of K2SiF6:Mn phosphor typically exceeds 50 nm, resulting in insufficient purity of the green light; while the red phosphor K2SiF6:Mn 4+ Although it is a narrowband transmitter, there is still room for improvement in its efficiency and stability.

[0003] To further improve the color gamut, researchers are dedicated to developing novel narrowband emitting phosphors, and have disclosed Eu... 2+ Doping and Mn 2+ The activated narrowband green phosphors emit only single-band light. To achieve high color gamut displays, it is usually necessary to physically mix the green and red phosphors, which can lead to uneven light emission, low energy transfer efficiency, complex device structures, and increased costs. Therefore, developing a phosphor that can be effectively excited by blue light and simultaneously generate narrowband green and red light in a single matrix is ​​of great significance for simplifying backlight structures, reducing costs, and achieving high color gamut displays. Mn element, due to its different valence states (Mn... 2+ Mn 4+ It can exhibit different emissions from green to red, making it an ideal choice for achieving this goal. However, the stable co-doping and charge balance of Mn with different valence states in the matrix are technical challenges in achieving high-performance dual narrowband emission. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel narrowband dual-color phosphor. This phosphor uses a highly symmetric hexagonal aluminate as a matrix and utilizes a charge compensation mechanism while being doped with Mn. 2+ and Mn 4+ When excited by blue light, it can simultaneously emit green and red light with extremely narrow half-width at half-maximum (HWHM).

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned dual narrowband phosphor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A narrowband dual-color phosphor excited by blue light for high color gamut displays is based on a highly symmetric hexagonal aluminate matrix, utilizing alkali metals for charge compensation and simultaneously doping with Mn. 2+ and Mn 4+ The resulting narrowband dual-color phosphor.

[0008] Preferably, the highly symmetric hexagonal aluminate is BaZnAl. 10 O 17 The narrowband dual-color phosphor has the general chemical formula: Ba 1-x M x ZnAl 10-x O 17 : xMn (x-type) or BaZn 1-y M y Al 10-y O 17 :yMn (y-type); where M is Li + Na + and K + At least one of them; x and y are the doping molar coefficients of Mn and M, and satisfy: 0 < x ≤ 0.025, 0 < y ≤ 0.025.

[0009] Specifically, as some possible solutions, for Ba 1-x M x ZnAl 10-x O 17 When x=0.01, the narrowband dual-color phosphor has the chemical formula: Ba. 0.99 M 0.01 ZnAl 9.99 O 17 :0.01Mn; When x=0.02, the chemical formula of the narrowband dual-color phosphor is: Ba 0.98 M 0.02 ZnAl 9.98 O 17 0.02Mn;

[0010] As for BaZn 1-y M y Al 10-y O 17 When y=0.01, the chemical formula of the narrowband dual-color phosphor is: BaZn. 0.99 M 0.01 Al 9.99 O 17 :0.01Mn, when y=0.02, the chemical formula of the narrowband dual-color phosphor is: BaZn 0.98 M0.02 Al 9.98 O 17 0.02Mn. It should be noted that for the x-type and y-type general formulas, the stoichiometric formula can be designed through synthesis and the determination can be made based on the ionic radius matching degree. In particular, when M is Li... + At that time, Li + Smaller radius, compared to Zn 2+ With a higher radius matching degree, it is easier to occupy Zn lattice sites, thus tending towards the y-type; when M is Na + and K + At that time, they tend to be more inclined towards type X.

[0011] Preferably, under blue light excitation at wavelengths of 440 nm to 470 nm, two narrow-band emission peaks are generated simultaneously: the first emission peak is located in the green light region of 515 nm to 520 nm with a full width at half maximum (FWHM) of less than 35 nm; the second emission peak is located in the red light region of 660 nm to 670 nm with a FWHM of less than 30 nm.

[0012] Preferably, the first emission peak originates from Mn occupying tetrahedral lattice sites. 2+ Ionic 4 T1→ 6 A1 transition; the second emission peak originates from Mn occupying octahedral lattice sites. 4+ of 2 E g → 4 A 2g Leap forward.

[0013] Preferably, the phosphor has a hexagonal crystal system with space group P63 / mmc, belonging to the β-Al2O3 structure type.

[0014] A method for preparing the narrowband dual-color phosphor includes the following steps:

[0015] S1. Ingredients: Weigh the compounds of barium source, zinc source, aluminum source, manganese source and charge compensator raw material according to the stoichiometric ratio of the general chemical formula, and mix them evenly.

[0016] S2. Sintering: The uniformly mixed raw materials are sintered at high temperature in air at a temperature range of 1300℃ to 1500℃.

[0017] S3. Post-processing: After cooling the sintered product, grind, wash and dry it to obtain the narrow-band dual-color phosphor.

[0018] Preferably, in step S1, the barium source is BaCO3, the zinc source is ZnO, the aluminum source is Al2O3, and the manganese source is MnO2; the charge compensator raw material is at least one of Li2CO3, Na2CO3, and K2CO3.

[0019] Preferably, in step S1, a flux is added when mixing the raw materials, and the amount of flux added is 5% to 10% of the total mass of the raw materials.

[0020] Preferably, the flux is at least one of H3BO3, AlF3, BaF2, and MgF2.

[0021] Preferably, before sintering in step S2, a pre-firing step is further included: the uniformly mixed raw materials are pre-firing at 600℃~900℃ for 2~5 hours in an air atmosphere to obtain a pre-firing product; the pre-firing product is then ground before sintering in step S2.

[0022] Preferably, the sintering time in step S2 is 4 to 8 hours; the washing in step S3 is carried out by washing with deionized water and anhydrous ethanol in sequence, and the drying temperature after washing is 80°C to 120°C.

[0023] This invention also provides a method for preparing the phosphor, the key of which lies in sintering in air atmosphere using a high-temperature solid-state method, and introducing a charge compensator Li. + Na + K + Mn was successfully implemented 2+ and Mn 4+ Stable coexistence and efficient luminescence in a single matrix.

[0024] Compared with the prior art, the beneficial technical effects of this invention are reflected in:

[0025] 1. Dual narrowband launch: First time in BaZnAl 10 O 17 Mn was achieved in the matrix using charge compensation technology 2+ and Mn 4+ The highly efficient co-doping yielded blue light-excited, dual-narrowband green and red light emission with extremely high color purity.

[0026] 2. Simplified device structure: A single phosphor can replace the traditional combination of green and red phosphors, simplifying the structure of the backlight module, avoiding problems caused by physical mixing, and reducing costs.

[0027] 3. High performance: The full width at half maximum (FWHM) of both emission peaks is very narrow (green light <35nm, red light <30nm), far superior to commercial β-SiAlON:Eu 2+ Green powder helps to achieve ultra-wide color gamut display.

[0028] 4. Excellent matching: The excitation band is perfectly matched with commercial blue LED chips, which facilitates industrial application.

[0029] 5. Mature preparation process: The classic high-temperature solid-state method is adopted, which is simple, has good repeatability, and is suitable for large-scale production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this patent. For those skilled in the art, other drawings can be obtained based on these drawings.

[0031] Figure 1 The image shows the XRD pattern of the Mn-doped dual narrowband fluorescent material prepared in Example 1 of this invention.

[0032] Figure 2 The images show the excitation and emission spectra of the red narrowband phosphor prepared in Example 1 of this invention.

[0033] Figure 3 The Li obtained in Examples 2-6 of this invention + Excitation and emission spectra of the compensated dual narrowband phosphor.

[0034] Figure 4 The Li obtained in Example 5 of this invention + The excitation and emission spectra of the compensated dual narrowband phosphor are shown. The excitation spectrum is before 500 nm (left line), and the emission spectrum is between 500 and 700 nm (right line).

[0035] Figure 5 The images show the excitation and emission spectra of the K⁺-compensated dual narrowband phosphors prepared in Examples 7-11 of this invention.

[0036] Figure 6 K obtained in Example 10 of the present invention + Excitation and emission spectra of the compensated dual narrowband phosphor.

[0037] Figure 7 Na obtained in Example 12 of this invention + Excitation and emission spectra of the compensated dual narrowband phosphor.

[0038] Figure 8 The white light device obtained by combining dual narrowband phosphors with a blue LED chip in Example 5 of this invention is compared with commercial β-SiAlON:Eu 2+ Green powder and K2SiF6:Mn 4+A comparison of the color gamut of red light and white light devices obtained by combining blue LED chips on the CIE 1931 chromaticity diagram. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0042] The preparation method of the phosphor of the present invention is as follows:

[0043] The narrowband dual-color phosphor of the present invention is prepared by a high-temperature solid-state reaction method, and the preparation method includes the following steps:

[0044] S1. Ingredients: According to the stoichiometric ratio of the target product, accurately weigh the barium source (such as BaCO3), zinc source (such as ZnO), aluminum source (such as Al2O3), manganese source (such as MnO2) and the corresponding charge compensator raw materials (Li2CO3, Na2CO3 or K2CO3), and add an appropriate amount of flux, such as adding 5% of the total mass of H3BO3 or 10% of the total mass of MgF2.

[0045] S2. Mixing: Place the weighed raw materials in a mortar (such as an agate mortar) and grind and mix thoroughly for 30-60 minutes until the mixture is homogeneous.

[0046] S3. Pre-calcination: Place the uniformly mixed raw materials in a high-temperature resistant container (such as a corundum crucible) and pre-calcine at 600-900°C (e.g., 800°C) in an air atmosphere for 2-5 hours (e.g., 3 hours). This step helps to remove volatile components and induces a preliminary solid-phase reaction in the raw materials.

[0047] S4. Sintering: After the pre-calcined intermediate product is ground again, it is placed in a sintering furnace (such as a tube furnace) and sintered at a high temperature of 1300-1500℃ (e.g., 1400℃) in an air atmosphere. The sintering time is usually 4-8 hours (e.g., 6 hours).

[0048] S5. Post-processing: After sintering, allow the product to cool naturally to room temperature in the furnace. Grind the obtained sintered block into fine powder, and then wash it sequentially with deionized water and anhydrous ethanol to remove impurities. The washing frequency can be 1-3 times (e.g., twice each). The washed powder is dried at 80-120℃ (e.g., 100℃), and finally sieved to obtain the final product of the narrow-band dual-color phosphor.

[0049] The technical solution and effects of the present invention are further illustrated below through four specific embodiments. Experimental methods not specifically described in the embodiments are generally performed according to conventional conditions in the art or conditions recommended by the manufacturer.

[0050] Example 1

[0051] In this embodiment, a Mn-doped comparative sample was prepared, with the chemical composition BaZnAl. 9.98 O 17 : 0.02Mn.

[0052] Preparation method: Weigh BaCO3, ZnO, Al2O3 and MnO2 according to the above stoichiometric ratio, and add 5% H3BO3 as a flux as part of the total mass of the raw materials. The subsequent mixing (grinding for 40 minutes), pre-firing (800℃, 3h), sintering (1400℃, 6h) and post-treatment steps are the same as the general method described above.

[0053] Performance characterization: The obtained product was analyzed by XRD, and the results are as follows: Figure 1 As shown. From Figure 1 As can be seen from the curve, its diffraction peaks are similar to those of BaZnAl. 10 O 17 The standard chromatograms are basically consistent, indicating that the synthesized phosphor has a β-Al2O3 structure. Figure 2 The excitation spectrum (monitoring wavelength 665 nm) and emission spectrum (excitation wavelength 468 nm) of the phosphor are shown. The excitation spectrum exhibits two distinct excitation bands in the 250-390 nm and 425-500 nm ranges, indicating that it can be effectively excited by commercially available 440-470 nm blue LED chips. The emission spectrum shows that under 468 nm excitation, the sample exhibits a sharp emission peak at approximately 665 nm with a full width at half maximum (FWHM) of less than 30 nm, which is typical for Mn. 4+ Ions in an octahedral field 2 E g → 4 A 2g Narrow-band transition luminescence was observed, but no obvious green light emission was observed.

[0054] Examples 2-6

[0055] Examples 2-6 show the preparation of a series of Li+ The dual-narrow-band phosphor, used as a charge compensator, has the chemical composition BaZn. 1- y Li y Al 1-y O 17 yMn, wherein Examples 2-6 correspond to y=0.005, y=0.010, y=0.015, y=0.020, and y=0.025, respectively. In particular, when y=0.020 (i.e., Example 5), the chemical composition is BaZn. 0.98 Li 0.02 Al 9.98 O 17 : 0.02Mn.

[0056] Preparation method: Weigh BaCO3, ZnO, Al2O3, MnO2, and Li2CO3 according to the above stoichiometric ratio, and add 10% MgF2 as a flux. Subsequent process steps are the same as in Example 1.

[0057] Performance characterization: Figure 3 The BaZn prepared in Examples 2-6 are shown. 1-y Li y Al 10-y O 17 The emission spectrum of the yMn sample under 450 nm blue light excitation clearly shows two well-separated narrow-band emission peaks. Figure 4 The spectrum before 500 nm is the excitation spectrum (left line), and the spectrum from 500 to 700 nm is the emission spectrum (right line). The figure shows the BaZn prepared in Example 5. 0.98 Li 0.02 Al 9.98 O 17 The emission spectrum of the 0.02Mn sample under 450 nm blue light excitation shows two regions: one in the green region at 515 nm with a full width at half maximum (FWHM) of approximately 26 nm; and the other in the red region at 665 nm with a FWHM of approximately 28 nm. Compared to Example 1, Li was introduced... + Subsequently, a strong Mn concentration appeared at 515 nm. 2+ Ion characteristic green light emission ( 4 T1→ 6 The red light emission intensity is relatively reduced (due to the A1 transition). This proves that Li... + The introduction of [a specific substance] effectively played a charge compensation role, promoting the partial [growth] of Mn [a specific substance]. 4+ Restored to Mn 2+ And stably occupying tetrahedral sites, thus realizing Mn 2+ With Mn 4+ Coexistence and efficient dual-color luminescence.

[0058] Examples 7-11

[0059] Examples 7-11 prepared a series of K + The dual-narrowband phosphor, used as a charge compensator, has the chemical composition Ba. 1- x K x ZnAl 10-x O 17 : xMn. Examples 7-11 correspond to x=0.005, x=0.010, x=0.015, x=0.020, and x=0.025, respectively. Specifically, when x=0.020 (i.e., Example 10), the chemical composition is Ba. 0.98 K 0.02 ZnAl 9.98 O 17 : 0.02Mn.

[0060] Preparation method: Weigh BaCO3, ZnO, Al2O3, MnO2, and K2CO3 according to the above stoichiometric ratio, and add 5% H3BO3 as a flux based on the total mass of the raw materials. The preparation process is the same as in Example 1.

[0061] Performance characterization: The excitation and emission spectra of the obtained series of phosphor samples are as follows: Figure 5 , Figure 6 As shown, Figure 6 The left-hand image shows the excitation spectrum at x=0.02, and the right-hand image shows the emission spectrum, both exhibiting typical dual-narrowband emission characteristics, indicating that K... + It can also serve as an effective charge compensator to achieve Mn 2+ / Mn 4+ Co-doped with dual-color luminescence.

[0062] Example 12

[0063] This embodiment prepared a Na + The dual-narrowband phosphor, used as a charge compensator, has the chemical composition Ba. 0.98 Na 0.02 ZnAl 9.98 O 17 : 0.02Mn.

[0064] Preparation method: Weigh BaCO3, ZnO, Al2O3, MnO2, and Na2CO3 according to the above stoichiometric ratio, and add 5% H3BO3 as a flux based on the total mass of the raw materials. The preparation process is the same as in Example 1.

[0065] Performance characterization: The excitation and emission spectra of the obtained phosphor are as follows Figure 7As shown. Its spectral characteristics are similar to those of Example 5. Under blue light excitation, narrow-band green light emission near 515 nm and narrow-band red light emission near 665 nm can also be observed, proving that Na + It is also effective as a charge compensator.

[0066] As can be seen from the above embodiments, the present invention introduces Li + Na + or K + Alkali metal ions were successfully used as charge compensators in BaZnAl 10 O 17 Mn was regulated and stabilized in a single matrix 2+ and Mn 4+ The coexistence of two valence states of ions. The resulting phosphor can be efficiently excited by commercial blue LED chips, simultaneously producing green and red light with extremely narrow half-widths (WHM) and extremely high color purity. Figure 8 This demonstrates a white light device obtained by combining dual narrowband phosphors with a blue LED chip, as shown in Example 5, and its compatibility with commercially available β-SiAlON:Eu. 2+ Green powder and K2SiF6:Mn 4+ A color gamut comparison of white light devices obtained by combining red and blue LED chips on the CIE 1931 chromaticity diagram, where commercial β-SiAlON:Eu 2+ Green powder and K2SiF6:Mn 4+ Red phosphors (all from Shenzhen Zhanwanglong Technology Co., Ltd.) were physically mixed at a mass ratio of 1:7, then mixed with AB glue and coated onto a blue LED chip to obtain white light emission. The solid triangles represent the evaluation parameters of commercially available mixed phosphors, and the dashed triangles represent the color gamut range of Example 5. The results show that the phosphor of the present invention can achieve a wider color gamut coverage and has significant advantages in the field of high-end LCD backlight.

[0067] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

[0068] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. A narrowband dual-color phosphor excited by blue light for high color gamut displays, which uses a highly symmetric hexagonal aluminate as a matrix, utilizes alkali metal for charge compensation, and simultaneously dops with Mn. 2+ and Mn 4+ The resulting narrowband dual-color phosphor.

2. The narrow-band dual-color phosphor as described in claim 1, characterized in that, The highly symmetric hexagonal aluminate is BaZnAl 10 O 17 The narrowband dual-color phosphor has the general chemical formula: Ba 1-x M x ZnAl 10-x O 17 : xMn or BaZn1₋ y M y Al 10- y O 17 yMn; where M is an alkali metal, including Li + Na + and K + At least one of them; x and y are the doping molar coefficients of Mn and M, and satisfy: 0 < x ≤ 0.025, 0 < y ≤ 0.

025.

3. The narrow-band dual-color phosphor according to claim 2, characterized in that, When excited by blue light with wavelengths from 440 nm to 470 nm, two narrow-band emission peaks are generated simultaneously: the first emission peak is located in the green light region from 515 nm to 520 nm, with a full width at half maximum (FWHM) of less than 35 nm; the second emission peak is located in the red light region from 660 nm to 670 nm, with a FWHM of less than 30 nm.

4. The narrow-band dual-color phosphor according to claim 3, characterized in that, The first emission peak originates from Mn occupying tetrahedral sites. 2+ Ionic 4 T1→ 6 A1 transition; the second emission peak originates from Mn occupying octahedral lattice sites. 4+ of 2 E g → 4 A 2g Leap forward.

5. The narrow-band dual-color phosphor according to any one of claims 1-4, characterized in that, Its crystal structure is hexagonal, space group P63 / mmc, and belongs to the β-Al2O3 structure type.

6. A method for preparing a narrowband dual-color phosphor as described in any one of claims 2-5, characterized in that, Includes the following steps: S1. Ingredients: Weigh the compounds of barium source, zinc source, aluminum source, manganese source and charge compensator raw material according to the stoichiometric ratio of the general chemical formula, and mix them evenly. S2. Sintering: The uniformly mixed raw materials are sintered at high temperature in air at a temperature range of 1300℃ to 1500℃. S3. Post-processing: After cooling the sintered product, grind, wash and dry it to obtain the narrow-band dual-color phosphor.

7. The method according to claim 6, characterized in that, In step S1, the barium source is BaCO3, the zinc source is ZnO, the aluminum source is Al2O3, and the manganese source is MnO2; the charge compensator raw material is at least one of Li2CO3, Na2CO3, and K2CO3.

8. The method according to claim 6 or 7, characterized in that, In step S1, a flux is added when mixing the raw materials, and the amount of flux added is 5% to 10% of the total mass of the raw materials; the flux is at least one of H3BO3, AlF3, BaF2, and MgF2.

9. The method according to claim 6, characterized in that, Before the sintering in step S2, a pre-firing step is also included: the uniformly mixed raw materials are pre-firing at 600℃~900℃ for 2~5 hours in an air atmosphere to obtain a pre-firing product; The pre-fired product is ground before being sintered in step S2.

10. The method according to claim 6, characterized in that, The sintering time in step S2 is 4 to 8 hours; the washing in step S3 is carried out by washing with deionized water and anhydrous ethanol in sequence, and the drying temperature after washing is 80°C to 120°C.

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