Cold and warm white light adjustable perovskite fluorescent powder prepared by ultrasonic-assisted hydrochloric acid method

Abstract

The invention discloses cold and warm white light adjustable perovskite fluorescent powder prepared by an ultrasonic-assisted hydrochloric acid method. The chemical general formula of the perovskite fluorescent powder is Cs2ZrCl6: xBiamp, 0 < = x < = 0.2, and 0 < = y < = 0.99. The purpose of the invention is to realize temperature-adjustable white light emission of lead-free rare earth-free perovskite under the excitation of ultraviolet light with different wavelengths. The preparation scheme comprises the following steps: 1, dissolving zirconium source powder, bismuth source powder and tellurium source powder in hydrochloric acid according to a certain proportion, and stirring to obtain a clear solution; 2, adding a certain proportion of cesium source powder into the clear solution; and 3, carrying out ultrasonic treatment, centrifugal washing and vacuum drying on the solution to obtain the lead-free and rare earth-free Cs2ZrCl6: xBiamp with adjustable cold and warm white light, the invention relates to yTe perovskite fluorescent powder. The preparation method comprises the following steps: preparing Cs2ZrCl6: xBiamp by using an ultrasonic-assisted hydrochloric acid method; the yTe perovskite fluorescent powder can realize emission from cold white light to warm white light by changing the excitation wavelength of ultraviolet light. The method disclosed by the invention is simple in preparation, short in time consumption, low in cost, green and environment-friendly; the yTe white-light fluorescent powder has a good application prospect in the field of solid-state illumination.

Description

Technical Field

[0001] The present invention belongs to the field of luminescent materials, and particularly relates to a warm and cold white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method. Background Art

[0002] With the continuous improvement of people's living standards, the demand for lighting is also increasing. From the traditional fire source at the beginning to incandescent lamps and fluorescent lamps, and then to the white light LEDs commonly used today, the luminous efficiency and color rendering index of lamps have been continuously improved. According to different scene requirements, there are also distinctions between cold white light and warm white light. The improvement of lighting level is on the one hand an embodiment of modern social civilization, and on the other hand an indication that the concept of environmental protection and energy conservation has taken root in people's hearts. Compared with traditional fossil energy lighting, LEDs have higher luminous efficiency, longer service life, higher integration, and more types of luminous colors. Compared with monochromatic LEDs, white light LEDs have richer usage scenarios and higher demands. White light LED technology has been widely used in fields such as lighting, television, displays, and automotive lamps. Although white light LED technology has made remarkable progress in many aspects and has become the mainstream choice, there are still some problems and challenges. First is the cost issue. The price of white light LEDs constructed using red, green, and blue LEDs is relatively high, especially in some new technologies and high-brightness applications. This makes the initial investment cost of white light LED lighting systems still relatively high in some situations. Secondly is the color temperature and spectrum problem. Mainstream white light LEDs use yellow phosphors combined with blue LEDs to achieve white light emission. Although the cost is low, the performance of blue LEDs decays relatively quickly. After long-term use, there are problems in color temperature and color, resulting in colors not being as natural as traditional light sources. Finally is the environmental problem. Although LEDs are more environmentally friendly than traditional light sources such as incandescent lamps, the phosphors in white light LEDs often contain rare earth elements, which not only lead to higher costs, but also make the recycling of rare earth elements more difficult, presenting potential environmental problems. Therefore, by combining ultraviolet LEDs and white light rare-earth-free phosphors to construct white light LEDs, not only can the cost of white light LEDs be reduced, but also the environmental problems brought by rare earth elements can be effectively avoided. At the same time, because ultraviolet LEDs are more stable than blue LEDs, the constructed white light LEDs can maintain the stability of color temperature and color while extending the service life.

[0003] There are also related studies on white light perovskite phosphors in the reported literature, such as Cs2Ag 0.4 Na 0.6 InCl6:Bi&Gd and Cs2NaInCl6:Sb 3+ &Er 3+ &Ho 3+White light perovskite phosphors such as etc. However, achieving white light emission through rare earth element doping faces the shortage of rare earth elements and potential environmental problems. In addition, the traditional hydrothermal method for preparing perovskite materials usually requires a high-temperature and high-pressure environment, with a long preparation cycle and a large consumption of hydrochloric acid. Therefore, it is not conducive to the large-scale preparation of perovskite phosphors. To solve the above problems, the present invention proposes a cold and warm white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method. By an ultrasonic-assisted method, a lead-free and rare earth-free Cs2ZrCl6 perovskite phosphor doped with Bi and Te elements is prepared under normal temperature and pressure conditions, which can achieve cold and warm tunable white light emission. In addition, the Cs2ZrCl6:xBi&yTe perovskite phosphor proposed by the present invention is easy to prepare, time-consuming short, low-cost, green and environmentally friendly, and has great potential in large-scale preparation and application. Summary of the Invention

[0004] In response to the improvement requirements reported in existing research, the present invention prepares a lead-free and rare earth-free Cs2ZrCl6 perovskite phosphor doped with Bi and Te elements by an ultrasonic-assisted hydrochloric acid method under normal temperature and pressure conditions. Under ultraviolet light excitation, this material can achieve white light emission. In addition, by changing the ultraviolet excitation wavelength, the switching from cold white light to warm white light can be achieved.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] Provide a cold and warm white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method, the chemical general formula of which is: Cs2ZrCl6:xBi&yTe, where 0≤x≤0.2 and 0≤y≤0.99.

[0007] A cold and warm white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method, the preparation method comprising the following steps:

[0008] Step (1): Weigh zirconium source, bismuth source, and tellurium source powders according to the stoichiometric ratio of the Cs2ZrCl6:xBi&yTe (0≤x≤0.2, 0≤y≤0.99) chemical formula, place them in a centrifuge tube, mix them, and add hydrochloric acid, and stir to obtain a clear solution.

[0009] Step (2): Weigh cesium source powder according to the stoichiometric ratio of Cs2ZrCl6:xBi&yTe (0≤x≤0.2, 0≤y≤0.99) in step (1) and add it to the clear solution obtained in step (1).

[0010] Step (3): Transfer the solution obtained in step (2) to an ultrasonic cleaner for ultrasonic treatment to obtain a suspension containing a large amount of precipitate. The ultrasonic power density is 2.5 - 4.5 kWm -2 , the ultrasonic frequency is 28 - 40 kHz, and the ultrasonic time is 3 - 10 minutes.

[0011] Step (4): Centrifuge and wash the suspension obtained in step (3), and then place it in a vacuum drying oven for drying. The drying temperature is 50 - 80 o °C, and the drying time is 180 - 300 minutes.

[0012] Step (5): Grind the sample obtained in step (4) evenly to obtain a Cs2ZrCl6:xBi&yTe white light perovskite phosphor with adjustable cooling and heating.

[0013] In summary, the beneficial effects of the present invention are as follows:

[0014] 1. The present invention provides a perovskite phosphor with adjustable cooling and heating white light. By doping Bi and Te elements, white light emission of lead-free and rare-earth-free perovskite is achieved. In addition, by adjusting the ultraviolet excitation wavelength, the switching from cold white light to warm white light can be realized.

[0015] 2. This technical solution uses an ultrasonic-assisted method to prepare Cs2ZrCl6:xBi&yTe perovskite phosphor under normal temperature and pressure conditions. The preparation method is simple, time-consuming short, low-cost, green and environmentally friendly, and can effectively solve the safety problems caused by the high-temperature and high-pressure environment in the traditional hydrothermal method.

[0016] 3. The Cs2ZrCl6:xBi&yTe perovskite phosphor prepared by this technical solution can be combined with ultraviolet LEDs to construct a single-component white LED, effectively avoiding the problem of short service life of blue LEDs.

[0017] 4. The Cs2ZrCl6:xBi&yTe perovskite phosphor prepared by this technical solution has a high color rendering index and good stability, and has good application prospects. Description of the Drawings

[0018] The present invention will be described by way of examples with reference to the drawings, wherein:

[0019] Figure 1 It is the X-ray diffraction pattern of the phosphors prepared in the comparative example and examples 1 - 2 of the present invention. Among the three curves from top to bottom, the first curve represents Cs2ZrCl6:0.05Bi&0.012Te, the second curve represents Cs2ZrCl6:0.05Bi&0.004Te, and the third curve represents the comparative example Cs2ZrCl6.

[0020] Figure 2The luminescence spectra of the phosphors prepared in the comparative example and Examples 1-2 of the present invention. Among the three curves from top to bottom, the first curve represents Cs2ZrCl6:0.05Bi&0.012Te, the second curve represents Cs2ZrCl6:0.05Bi&0.004Te, and the third curve represents the comparative example Cs2ZrCl6.

[0021] Figure 3 The luminescence spectra of the Cs2ZrCl6:0.05Bi&0.004Te phosphor prepared in Example 1 of the present invention under different excitation wavelengths. Among the three curves from top to bottom, the first curve has an excitation wavelength of 350 nm to achieve cold white light emission; the second curve has an excitation wavelength of 370 nm to achieve quasi-white light emission; the third curve has an excitation wavelength of 400 nm to achieve warm white light emission.

[0022] Figure 4 The photograph of the white light LED constructed by combining the Cs2ZrCl6:0.05Bi&0.004Te phosphor prepared in Example 1 of the present invention with an ultraviolet LED. (a) The photograph of the Cs2ZrCl6:0.05Bi&0.004Te phosphor prepared in Example 1 combined with a 365 nm ultraviolet LED, (b) The photograph of the Cs2ZrCl6:0.05Bi&0.004Te phosphor prepared in Example 1 combined with a 395 nm ultraviolet LED. Detailed implementation mode

[0023] The present invention will be elaborated in detail below with reference to the accompanying drawings.

[0024] Comparative example: a) Weigh 0.233 g of zirconium chloride powder and place it in a centrifuge tube. Add 3 ml of hydrochloric acid with a concentration of 36-38%, and gently shake until the powder is completely dissolved to obtain a clear solution; b) Weigh 0.3367 g of cesium chloride powder and add it to the clear solution obtained in step a). Place the centrifuge tube containing the solution in an ultrasonic cleaner and ultrasonically treat it for 5 minutes (ultrasonic power density is 3.5 kWm -2 , ultrasonic frequency is 40 kHz) to obtain a suspension containing a large amount of precipitate; c) Centrifuge the suspension obtained in step b) at a speed of 5000 rpm for 120 seconds, and pour out the supernatant. Add 5 ml of absolute ethanol to the centrifuge tube, shake well, centrifuge at a speed of 5000 rpm for 120 seconds, pour out the supernatant, and put the precipitate into a vacuum drying oven at 60 o C and dry for 300 minutes. After naturally cooling to room temperature, grind it to obtain the Cs2ZrCl6 phosphor.

[0025] Example 1: a) Weigh 0.233 g of zirconium chloride powder, 0.0158 g of bismuth chloride powder and 0.0006 g of tellurium oxide powder in sequence according to the chemical formula Cs2ZrCl6:0.05Bi&0.004Te, place them in a centrifuge tube, mix them, and add 3 ml of hydrochloric acid with a concentration of 36 - 38%. Gently shake until the powder is completely dissolved to obtain a clear solution; b) Weigh 0.3367 g of cesium chloride powder and add it to the clear solution obtained in step a). Place the centrifuge tube containing the solution in an ultrasonic cleaner and ultrasonically treat it for 5 minutes (ultrasonic power density is 3.5 kWm -2 , ultrasonic frequency is 40 kHz) to obtain a suspension containing a large amount of precipitate; c) Centrifuge the suspension obtained in step b) at a speed of 5000 rpm for 120 seconds, and pour out the supernatant. Add 5 ml of absolute ethanol to the centrifuge tube, shake it well, centrifuge it at a speed of 5000 rpm for 120 seconds, pour out the supernatant, and put the precipitate into a vacuum drying oven. Dry it at 60 o °C for 300 minutes. After naturally cooling to room temperature, grind it to obtain the Cs2ZrCl6:0.05Bi&0.004Te phosphor.

[0026] Example 2: a) Weigh 0.233 g of zirconium chloride powder, 0.0158 g of bismuth chloride powder and 0.0019 g of tellurium oxide powder in sequence according to the chemical formula Cs2ZrCl6:0.05Bi&0.012Te, place them in a centrifuge tube, mix them, and add 3 ml of hydrochloric acid with a concentration of 36 - 38%. Gently shake until the powder is completely dissolved to obtain a clear solution; b) Weigh 0.3367 g of cesium chloride powder and add it to the clear solution obtained in step a). Place the centrifuge tube containing the solution in an ultrasonic cleaner and ultrasonically treat it for 5 minutes (ultrasonic power density is 3.5 kWm -2 , ultrasonic frequency is 40 kHz) to obtain a suspension containing a large amount of precipitate; c) Centrifuge the suspension obtained in step b) at a speed of 5000 rpm for 120 seconds, and pour out the supernatant. Add 5 ml of absolute ethanol to the centrifuge tube, shake it well, centrifuge it at a speed of 5000 rpm for 120 seconds, pour out the supernatant, and put the precipitate into a vacuum drying oven. Dry it at 60 o °C for 300 minutes. After naturally cooling to room temperature, grind it to obtain the Cs2ZrCl6:0.05Bi&0.012Te phosphor.

[0027] The above-described embodiments are only used to explain the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation of the protection scope of the present application. It should be noted that for those of ordinary skill in the art, any modifications and changes made to the present invention without departing from the concept of the technical solution of the present application fall within the protection scope of the present application.

Claims

1. A warm and cool white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method, characterized in that, The phosphor has a perovskite structure, and its chemical general formula is: Cs2ZrCl6:xBi&yTe, where 0 ≤ x ≤ 0.2 and 0 ≤ y ≤ 0.

99.

2. Preparation of the warm and cold white light tunable perovskite phosphor as described in claim 1, characterized in that, It includes the following steps: (1) Weigh zirconium source, bismuth source, and tellurium source powders according to the stoichiometric ratio of the chemical formula Cs2ZrCl6:xBi&yTe (0 ≤ x ≤ 0.2, 0 ≤ y ≤ 0.99), place them in a centrifuge tube for mixing, add hydrochloric acid, and stir to obtain a clear solution; (2) Weigh cesium source powder according to the stoichiometric ratio of the chemical formula Cs2ZrCl6:xBi&yTe (0 ≤ x ≤ 0.2, 0 ≤ y ≤ 0.99) in step (1) and add it to the clear solution obtained in step (1); (3) Transfer the mixed solution obtained in step (2) to an ultrasonic cleaner for ultrasonic treatment, wash, centrifuge, dry, and grind to obtain the Cs2ZrCl6:xBi&yTe perovskite phosphor with adjustable cold and warm white light.

3. The preparation method according to claim 2, characterized in that, Use an ultrasonic-assisted solution method to prepare the Cs2ZrCl6:xBi&yTe perovskite phosphor.

4. The preparation method according to claim 2, wherein The zirconium source powder used includes zirconium carbonate and zirconium chloride; the bismuth source powder used includes bismuth chloride and bismuth oxide; the tellurium source powder used includes tellurium oxide and tellurium chloride; the cesium source powder used includes cesium chloride, cesium oxide, and cesium carbonate.

5. The warm-cold white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method according to claim 1, wherein The prepared Cs2ZrCl6:xBi&yTe phosphor can achieve white light emission.

6. The tunable warm and cool white perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method according to claim 1, wherein, By changing the excitation wavelength, the Cs2ZrCl6:xBi&yTe phosphor can achieve the switching from cold white light emission to warm white light emission.

7. The warm-cold white light tunable perovskite phosphor prepared by an ultrasonic-assisted hydrochloric acid method as described in claim 1, wherein, The Cs2ZrCl6:xBi&yTe phosphor combined with an ultraviolet light-emitting diode (LED) can be applied to the field of solid-state lighting.

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