A single-component all-inorganic warm white light material and its preparation method

Abstract

The present invention discloses a single-component all-inorganic warm white light material and its preparation method. The matrix chemical composition of the material is: Cs2Nb 1‑x Cl6:xTe 4+ (x=1%-15%), achieving single-component warm white light. The preparation method is as follows: using CsCl and Nb2O5 as matrix raw materials, TeO2 as activator raw material, and HCl acid solution as medium, the raw materials are ultrasonically dispersed and mixed evenly at room temperature according to the stoichiometric ratio. Load into the reactor, heat to react for 3 to 16 hours, then slowly cool to room temperature, wash the obtained crystals twice with ethanol, and bake at 60 to 80°C for 2 to 8 hours to obtain the product. The product emits bright warm white light under the excitation of the ultraviolet LED chip, and the excitation spectrum is at 402nm, which is completely matched with the wavelength of commercial near-ultraviolet light chips. The product particles are uniform and fine, do not contain rare earths and lead and cadmium, the raw materials are cheap and easily available, the preparation method is simple, and it is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to a warm white light material, in particular to a single-component all-inorganic warm white light material and a preparation method thereof, and belongs to the technical field of inorganic solid luminescent materials. Background Art

[0002] In the field of solid-state lighting, the development of luminescent materials is of great significance for improving lighting efficiency and environmental friendliness. However, traditional luminescent materials contain toxic elements or complex multi-component structures, which will affect their application prospects. In recent years, all-inorganic luminescent materials have become a research hotspot because of their good stability, high efficiency and environmental friendliness. However, some known all-inorganic perovskite luminescent materials contain toxic elements such as lead and cadmium, which has caused environmental and health concerns [Liu, X.; Zhang, Y.; Zhu, C.; Yin, J.; Li, S.; Wang, Y.; Sun, C.; Wang, Z.; Hao, X. Engineering of inorganic perovskite nanocrystals foroptoelectronics. Adv. Mater. 2021, 33, 2100316.]. Therefore, it is necessary to develop non-toxic and efficient luminescent materials to achieve ideal luminescent performance.

[0003] Traditionally, achieving warm white light usually requires the use of multi-component luminescent materials, such as using a blue light chip to simultaneously excite yellow and red light materials, or using a near-violet light chip to simultaneously excite blue, green, and red light-emitting materials, which requires complex packaging processes. In addition, traditional luminescent materials such as nitride red powder require sintering above 1600 degrees, while the widely used yellow light material Y3Al5O 12 :Ce 3+ (YAG:Ce) requires sintering above 1500 degrees [Wu, X.; Zhang, Y.; Ouyang, X.; Ma, H.; Chen, J. One-pot synthesis of Y3Al5O 12 :Ce 3+ [phosphor by the molten salt method and its luminescent properties. J. Alloys Compd. 2017, 722, 129-135.] Another method is to dope different ions into a single-component luminescent material matrix to achieve multi-band luminescence, thereby forming white light. However, this multi-component structure easily leads to luminescence cross-relaxation between ions, thereby reducing the luminescence efficiency. Therefore, a simpler and more efficient method is needed to achieve warm white light luminescence.

[0004] Organic-inorganic hybrid luminescent materials can achieve full white light with a single emission band, but the matrix of these hybrid materials is unstable, which limits their widespread use in practical applications. Therefore, there is a need for an all-inorganic luminescent material that can be prepared with a single component and has stability and high luminescence efficiency to meet various application requirements. For example, all-inorganic halide perovskite crystals have a broadband energy band structure and can achieve multicolor luminescence by adjusting the composition and structure [Zhao, Y.; Gao, X.; Zhang, L.; Xu, Z.; Zhang, Y. Low temperature synthesis of all-inorganic perovskitenanocrystals: A review. Chin. Chem. Lett. 2021, 32, 1905-1915.]. However, some known all-inorganic perovskite luminescent materials contain toxic elements such as lead and cadmium, which has caused environmental and health concerns. In recent years, researchers have successfully synthesized a series of non-toxic materials, such as Cs2B I B III X6(B I =Ag + ,Na + ,K + ,Cs + ,etc.,B III =Bi 3+ ,Sb 3+ ,In 3+ ,X=Cl-,Br - ,I - ) and other materials have successfully solved the toxicity problem of traditional luminescent materials [Li, X.; Chen, B.; Kang, L.; Cai, M.; Huang, J. Recent advances in all-inorganic halide perovskites for optoelectronics. Nano Res. 2021, 14, 3363-3382.]. However, we still need to further study various strategies to improve the performance of luminescent materials, including improving the photoluminescence quantum yield, stability and tunability.

[0005] Therefore, we will continue to explore new all-inorganic luminescent materials and their optimized preparation methods to meet market demand. At the same time, we also need to conduct in-depth research on the performance of the materials and their luminescence mechanisms to further improve their stability and tunability, so as to promote the widespread application of all-inorganic luminescent materials in practical applications. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a single-component all-inorganic warm white light material and a preparation method thereof. The material is suitable for large-scale production, emits pure warm white light, has a simple preparation method, uses cheap and readily available raw materials, has a maximum excitation wavelength in the near-UV light region, and can efficiently absorb the near-ultraviolet light of a gallium nitride chip and emit warm white light.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A fully inorganic warm white light material for white light LED, the matrix chemical composition of the material is: Cs2NbCl6, doped with tetravalent Te 4+ Replace part of Nb 4+ The excitation spectrum of the all-inorganic warm white light material consists of a wide excitation band with a wavelength of 300 to 450 nm, with the highest at 402 nm, which is completely matched with the wavelength of commercial near-UV light chips; the emission band Te of the warm white light LED with an emission wavelength of 450 to 750 nm is 4+ The characteristic emission of is in the warm white light region.

[0009] The preparation method of the all-inorganic warm white light material for white light LED is as follows: solid raw materials cesium chloride (CsCl) and niobium pentoxide (Nb2O5) are prepared according to the stoichiometric molar ratio of Cs2NbCl6, and HCl acid solution with a concentration of 5-40wt% is used as the medium. The raw materials are mixed and dissolved uniformly according to the stoichiometric ratio, ultrasonically dispersed at room temperature for 5 minutes, added to a sealed polytetrafluoroethylene high-pressure reactor, heated at 60-200°C for reaction for 3-16 hours, and then slowly cooled to room temperature at a rate of 6°C per hour. The obtained powder is washed twice with ethanol and dried at 80°C for 6 hours to obtain the all-inorganic warm white light material for white light LED. It is worth noting that the oxide raw material Nb2O5 contains pentavalent niobium Nb 5+ , in a weak HCl solution, is reduced to tetravalent Nb 4+ .

[0010] To further achieve the purpose of the present invention, preferably, the mass concentration of the medium HCl acid solution is 25 to 35 wt%.

[0011] Preferably, the temperature of the hydrothermal reaction is 90-180°C.

[0012] Preferably, the hydrothermal reaction time is 8 to 14 hours.

[0013] Compared with the prior art, the present invention has the following advantages and effects:

[0014] (1) The excitation spectrum consists of a wide excitation band with a wavelength of 300 to 450 nm, with the highest at 402 nm, which is completely matched with the wavelength of commercial near-UV light chips. The emission peak is in the warm white light region, which shows that the invention can be applied to purple LEDs.

[0015] (2) The chemical composition of the matrix of the present invention is Cs2NbCl6:Te 4+ It is a fully inorganic material, which not only avoids the defects of poor stability and easy decomposition of organic and inorganic white light materials, but also avoids the disadvantages of complex preparation process, harsh preparation environment and high product cost of nitride phosphors.

[0016] (3) The matrix structure of the present invention is simple and only one ion needs to be doped to obtain a warm white light material, and it does not contain toxic lead and cadmium. The preparation process is simple and easy, the synthesis technology is low in difficulty, and it is suitable for large-scale production.

[0017] (4) The present invention does not require expensive metal elements such as titanium, germanium, and silicon raw materials, and does not contain rare earths. The preparation process does not require water and oxygen avoidance, and does not require high-temperature sintering. 3+ Compared with ion-doped white light materials, it has significant cost advantages.

[0018] In summary, this material only requires a single component to achieve warm white light, greatly simplifying the complexity of materials and processes. Compared with traditional luminescent materials, this single-component all-inorganic warm white light material is more cost-effective and environmentally friendly. The preparation method of this single-component all-inorganic warm white light material is also a major innovation. Traditional multi-component luminescent materials require complex preparation processes such as high-temperature sintering, while this material only needs to be synthesized using a hydrothermal method below 200 degrees, which is low-cost and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The standard card data of Cs2NbCl6 phase and the product Cs2NbCl6:Te obtained in Example 1 4+ XRD pattern of .

[0020] Figure 2 The warm white light material Cs2NbCl6:Te obtained in Example 1 of the present invention 4+ The excitation spectrum (monitoring wavelength is 564 nm).

[0021] Figure 3 The warm white light material Cs2NbCl6:Te obtained in Example 1 of the present invention 4+ Emission spectrum (excitation wavelength is 402 nm). DETAILED DESCRIPTION

[0022] The present invention will be described in further detail below with reference to the embodiments and drawings. However, the scope of protection claimed by the present invention is not limited to the scope shown in the embodiments.

[0023] Example 1

[0024] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.03 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 25wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 90℃ for heating and reaction for 8 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 60℃ for 5 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. Its XRD (detected by BrukerD8 Advance X-ray diffractometer) is as follows Figure 1 As shown in the figure, there are no other impurity peaks compared with the standard card, indicating that the product is a pure Cs2NbCl6 phase. Figure 2 As shown in the figure, the luminescence performance of the product was tested at room temperature using a Fluoromax-4 fluorescence spectrometer (HORIBA Jobin Yvon Inc.). The excitation spectrum of the product at a monitoring wavelength of 564 nm was composed of a wide excitation band located between 300 and 450 nm, with the highest peak located at 402 nm, which fully matches the wavelength of commercial near-UV light chips. Figure 3 As shown, the emission peak is 450-750nm, covering the entire visible light region and showing warm white light.

[0025] Example 2

[0026] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.01 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 5wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 60℃ for heating and reaction for 16 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 60℃ for 8 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0027] Example 3

[0028] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.05 in this embodiment) into a beaker, add 7ml of 15wt% HCl solution, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 150℃ for heating and reaction for 15 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 70℃ for 2 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0029] Example 4

[0030] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.09 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 20wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 120℃ for heating and reaction for 3 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 80℃ for 2 hours to obtain a fully inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0031] Example 5

[0032] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.15 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 40wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 60℃ for heating and reaction for 16 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 60℃ for 8 hours to obtain a fully inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0033] Example 6

[0034] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.15 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 35wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 200℃ for heating and reaction for 3 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 70℃ for 4 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0035] Example 7

[0036] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.10 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 35wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 180℃ for heating and reaction for 5 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 80℃ for 4 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0037] Example 8

[0038] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.09 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 35wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 90℃ for heating and reaction for 12 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 60℃ for 8 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0039] Example 9

[0040] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.07 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 40wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 120℃ for heating and reaction for 10 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 80℃ for 2 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0041] Example 10

[0042] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.05 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 40wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 90℃ for heating and reaction for 12 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 80℃ for 8 hours to obtain a fully inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0043] Example 11

[0044] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.02 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 20wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 70℃ for heating and reaction for 3 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 80℃ for 5 hours to obtain a fully inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0045] Example 12

[0046] Accurately weigh solid raw materials 4mmol CsCl, (1-0.5x)mmol Nb2O5, xmmol TeO4 (x=0.07 in this embodiment) into a beaker, add 7ml of HCl solution with a mass concentration of 25wt%, ultrasonically disperse at room temperature for 5 minutes, add to a sealed polytetrafluoroethylene high-pressure reactor, place it at 80℃ for heating and reaction for 5 hours, take out the reactor and slowly cool it to room temperature, filter it, wash the obtained powder with ethanol twice, and dry it at 60℃ for 5 hours to obtain an all-inorganic warm white light material for white light LED. The product is a light yellow powder under natural light and emits bright warm white light under ultraviolet light. The XRD of the light yellow powder material Figure 1 The fluorescence spectrum is similar to that of Cs2NbCl6. Figure 2 、 Figure 3 The shape is basically the same, but the strength is different.

[0047] As can be seen from the above embodiments, the excitation spectrum of the present invention consists of two groups of broad peaks, located in the near-ultraviolet region and the blue light region respectively. Compared with many similar systems currently available, which only have excitation below 400 nm, the present invention has a great advantage. The emission peak is located in the warm white light region. It can be seen that the present invention can be applied to purple LEDs and blue LEDs.

[0048] The chemical composition of the matrix of the present invention is Cs2NbCl6:Te 4+It is a fully inorganic material, which not only avoids the defects of poor stability and easy decomposition of organic-inorganic hybrid phosphors, but also avoids the disadvantages of complex preparation process, harsh preparation environment and high product cost of nitride phosphors.

[0049] The matrix structure of the present invention is simple and undoped, and does not need to be Ce-based like the mainstream warm white light materials. 3+ It is doped with ions and does not contain toxic lead and cadmium. The preparation process is simple and easy, the synthesis technology is low in difficulty, and it is suitable for large-scale production.

[0050] The present invention does not require expensive metal elements such as titanium, germanium, and silicon raw materials, does not contain rare earths, and does not require water and oxygen avoidance or high-temperature sintering during the preparation process. Therefore, it has significant cost advantages.

Claims

1. A single-component all-inorganic warm white light material, characterized by: The matrix chemical composition of the all-inorganic warm white light material is a pure niobium-based chloride Cs2NbCl6 crystal phase, doped with Te 4+ Ions replace part of the central ion Nb 4+ , the replacement concentration is 1%-15%.

2. The single-component all-inorganic warm white light material according to claim 1, characterized in that: The single-component all-inorganic warm white light material emits bright warm white light under the irradiation of ultraviolet light. The excitation spectrum of the all-inorganic warm white light material consists of a wide excitation band with a wavelength between 300 and 450 nm, with a maximum at 402 nm, which is completely matched with the wavelength of commercial near-UV light chips; the emission wavelength is the emission band of warm white light LEDs with a wavelength of 450 to 750 nm.

3. The method for preparing the single-component all-inorganic warm white light material according to claim 1, characterized in that: Using CsCl and Nb2O5 as matrix raw materials, TeO2 as activator raw material, and HCl solution as medium, the raw materials are ultrasonically dispersed at room temperature for 5 minutes according to the stoichiometric ratio, mixed evenly and added to a sealed polytetrafluoroethylene reactor, and the product is obtained after hydrothermal reaction.

4. The method for preparing a single-component all-inorganic warm white light material according to claim 3, wherein: The reaction matrix raw materials CsCl and Nb2O5 are added in a stoichiometric molar ratio of Cs2NbCl6, i.e. the feeding ratio of CsCl to Nb2O5 is 2:0.

5. To achieve doped luminescence, the TeO2 input is 1%-15% Cs2NbCl6, and the Nb2O5 is correspondingly reduced to 99.5% to 92.5%.

5. The method for preparing a single-component all-inorganic warm white light material according to claim 3, characterized in that: The mass concentration of the medium HCl solution in the synthesis reaction system is 5~40 wt%.

6. The method for preparing a single-component all-inorganic warm white light material according to claim 3, characterized in that: The hydrothermal reaction temperature is 60~200 ℃.

7. The method for preparing a single-component all-inorganic warm white light material according to claim 3, characterized in that: The hydrothermal reaction time is 3 to 16 hours.

8. The method for preparing a single-component all-inorganic warm white light material according to claim 3, characterized in that: Product drying conditions: 60~80℃ for 2~8 hours.

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