CeO2 / Cs4PbBr6 luminescent nano-cluster with fluorescence intensity regulated along with temperature as well as preparation method and application of CeO2 / Cs4PbBr6 luminescent nano-cluster

Abstract

The invention belongs to the technical field of preparation of nano composite materials, and particularly relates to a CeO2 / Cs4PbBr6 light-emitting nano cluster with fluorescence intensity regulated along with temperature as well as a preparation method and application of the CeO2 / Cs4PbBr6 light-emitting nano cluster. The CeO2 / Cs4PbBr6 luminescent nano-cluster is prepared by taking CeO2 as a carrier and Cs4PbBr6 as a luminescent material under the condition of not adding any surfactant, inducer or stabilizer, the fluorescence intensity of the CeO2 / Cs4PbBr6 luminescent nano-cluster can be regulated and controlled along with the temperature, and the optical performance of a prepared sample can be recovered after the prepared sample is heated at the high temperature of 180 DEG C. The material has a wide application prospect in photoelectric devices for illumination, display and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanocomposite material preparation, and specifically relates to a CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters and preparation methods and applications thereof. Background Art

[0002] In recent years, cesium lead halide perovskite materials have received extensive attention due to their advantages such as high fluorescence quantum yield and high chromatographic purity, and are widely used in display, lighting, light-emitting diodes, photodetectors, anti-counterfeiting codes, etc. Although cesium lead halide perovskite materials have excellent optical properties, the thermal stability of the structure to the external environment is poor, which greatly limits the practical application of cesium lead halide perovskite materials.

[0003] In order to improve the stability of cesium lead halide perovskite materials, the prior art often uses encapsulation, loading and other methods to improve their temperature stability, such as Angewandte Chemie International Edition, 2016, 55 (28): 7924-7929; Journal of Materials Chemistry C, 2017, 5 (30): 7431-7435; ACS applied materials & interfaces, 2017, 9 (31): 26556-26564; Advanced Optical Materials, 2020, 8 (4): 1901516 and patent publication number CN118421295A. However, the above improved methods are not only complicated in preparation process and difficult to operate, but also require the use of many toxic and harmful surfactants, inducers or stabilizers, and most of the prepared samples have relatively low tolerance to high temperature, which will face huge challenges in the future commercialization process.

[0004] Cerium dioxide nanomaterials have a high specific surface area, good stability and high mechanical strength, and are often suitable for loading perovskite materials to improve their stability. At present, there are few reports on the preparation of cesium lead halide perovskite materials with fluorescence intensity that can be controlled with temperature using ceria nanomaterials as carriers. Summary of the invention

[0005] The present invention aims to provide a CeO 2 / Cs 4 PbB 6The luminescent nanoclusters and their preparation methods and applications overcome the shortcomings of the prior art. The prepared samples can restore their optical properties after being heated at 180°C, and have broad application prospects in optoelectronic devices such as lighting and display.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In the first aspect, the present invention provides a CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters, the luminescent nanoclusters are composed of CeO 2 Carrier and Cs 4 PbB 6 The luminescent material composition comprises a molar ratio of cerium element to cesium element of 1:4; a molar ratio of cesium element to lead element of 30:(2-6).

[0008] In some other embodiments, the particle size of the luminescent nanocluster is 20-100 nanometers; it has a fluorescence emission peak at 520 nm, and an absolute fluorescence quantum yield of 34%.

[0009] In some other embodiments, the luminescent nanoclusters have the following fluorescence intensity characteristics at different temperatures: the fluorescence intensity at 70°C is 73% of that at room temperature; the fluorescence intensity at 100°C is 51% of that at room temperature; the fluorescence intensity at 150°C is 19% of that at room temperature; the fluorescence intensity at 180°C is 7% of that at room temperature; and the initial fluorescence intensity can be restored after cooling from 180°C to room temperature.

[0010] In a second aspect, the present invention provides a CeO2 having a fluorescence intensity controlled by temperature as described in the first aspect. 2 / Cs 4 PbB 6 The method for preparing the luminescent nanocluster comprises the following steps:

[0011] (1) mixing cerium nitrate hexahydrate, cesium bromide and deionized water, freeze-drying to obtain a lyophilized powder, and grinding and calcining the lyophilized powder to obtain a solid powder;

[0012] (2) mixing lead bromide with N,N-dimethylformamide to obtain an N,N-dimethylformamide solution of lead bromide;

[0013] (3) Mixing the solid powder, the N,N-dimethylformamide solution of lead bromide and N,N-dimethylformamide to obtain a mixed solution; centrifuging, drying and grinding to obtain CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters.

[0014] In some other embodiments, in step (1), the molar ratio of cerium nitrate to cesium bromide is 1:(3.5-4.5);

[0015] The freeze drying temperature is -55 to -65°C and the time is 40 to 50 hours;

[0016] The calcination temperature is 200-300° C. and the calcination time is 1-5 hours.

[0017] In some other embodiments, in step (1), the molar ratio of cerium nitrate to cesium bromide is 1:4;

[0018] The freeze drying temperature is -60°C and the time is 48h;

[0019] The calcination temperature is 250° C. and the calcination time is 2 h.

[0020] In some other embodiments, in the step (2), the mixing ratio of lead bromide to N,N-dimethylformamide is (0.1-0.2) g:1 mL.

[0021] In some other embodiments, in step (2), the mixing ratio of lead bromide to N,N-dimethylformamide is 0.1835 g:1 mL.

[0022] In some other embodiments, in step (3), the mixing ratio of the solid powder, the N,N-dimethylformamide solution of lead bromide and N,N-dimethylformamide is: 0.2 g: (100-220) μL: (30-150) μL.

[0023] In a third aspect, the present invention provides a CeO2 having a fluorescence intensity controlled by temperature as described in the first aspect. 2 / Cs 4 PbB 6 Applications of luminescent nanoclusters in displays, lighting, light-emitting diodes, photodetectors, and anti-counterfeiting codes.

[0024] Beneficial effects of the present invention:

[0025] (1) The present invention successfully prepared CeO with fluorescence intensity that can be controlled by temperature. 2 / Cs 4 PbB 6 The luminescent nanoclusters not only have excellent optical properties, but also their fluorescence intensity can be adjusted with temperature. That is, at 70°C, the fluorescence intensity of the sample is reduced to 73% of room temperature, at 100°C, the fluorescence intensity is reduced to 51% of room temperature, at 150°C, the fluorescence intensity is reduced to 19% of room temperature, and at 180°C, the fluorescence intensity is reduced to 7% of room temperature; the initial fluorescence intensity can be restored after cooling from 180°C to room temperature.

[0026] (2) CeO in the present invention 2 / Cs 4 PbB 6 The luminescent nanoclusters are based on CeO 2 As carrier, Cs 4 PbB 6 It is a luminescent material prepared without adding any surfactant, inducer or stabilizer. Its fluorescence intensity can be regulated with temperature, and the prepared sample can restore its optical properties after being heated at 180°C.

[0027] (3) CeO prepared by the present invention 2 / Cs 4 PbB 6 The size of the luminescent nanoclusters is 20-100 nanometers, with an emission peak at around 520 nanometers and an absolute fluorescence quantum yield of 34%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 Optical photos of luminescent nanoclusters taken with a digital camera after grinding; (a) CeO 2 / Cs 4 PbB 6 Optical photograph of luminescent nanocluster powder; (b) CeO 2 / Cs 4 PbB 6 Optical photograph of luminescent nanocluster powder under 365 nm UV light;

[0030] Figure 2 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 Fluorescence spectra and fluorescence quantum efficiency of luminescent nanoclusters;

[0031] Figure 3 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 X-ray diffraction patterns of luminescent nanoclusters;

[0032] Figure 4 is CeO in Example 1 of the present invention 2 / Cs 4PbB 6 Transmission electron microscope image of luminescent nanoclusters;

[0033] Figure 5 is CeO in Example 2 of the present invention 2 / Cs 4 PbB 6 Transmission electron microscope image of luminescent nanoclusters;

[0034] Figure 6 is CeO in Example 3 of the present invention 2 / Cs 4 PbB 6 Transmission electron microscope image of luminescent nanoclusters;

[0035] Figure 7 In Example 1 of the present invention, CeO 2 / Cs 4 PbB 6 Optical photos of the luminescent nanoclusters taken with a digital camera under 365-nanometer ultraviolet light, gradually heated from room temperature to 180°C and then returned to room temperature;

[0036] Figure 8 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 Fluorescence spectra of luminescent nanoclusters at different temperatures;

[0037] Fig. 9 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 The corresponding fluorescence spectra of the luminescent nanoclusters at room temperature and after being heated to 180 °C and gradually restored to room temperature. DETAILED DESCRIPTION

[0038] Unless otherwise specified, the present invention prepares CeO 2 / Cs 4 PbB 6 The raw materials used in the luminescent nanoclusters, lead bromide, cesium bromide, N,N-dimethylformamide, and cerium nitrate hexahydrate, are all commercially available products; among them, deionized water is obtained by a Lichun LCT-I-10T water purifier.

[0039] The content of the present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the specific examples listed below.

[0040] Example 1

[0041] (1) Accurately weigh 0.868 g of cerium nitrate hexahydrate and 1.704 g of cesium bromide, add them to 10 mL of deionized water, stir them thoroughly to dissolve, and obtain a mixed aqueous solution. Place the mixed aqueous solution in a refrigerator, freeze it completely, and then freeze it using a vacuum freeze dryer to obtain a freeze-dried powder; wherein the mass ratio of cerium to cesium is 1:4. After fully grinding the freeze-dried powder, calcine it at 250°C for 2 h, cool it to room temperature, and grind it to obtain a calcined powder.

[0042] (2) Accurately weigh 1.835 g of lead bromide and add it to 10 mL of N,N-dimethylformamide. Mix thoroughly to obtain a lead bromide solution in N,N-dimethylformamide.

[0043] (3) Weigh 0.2 g of the calcined powder, add 213 μL of N,N-dimethylformamide solution of lead bromide and 37 μL of N,N-dimethylformamide, stir thoroughly to obtain a mixed solution, which turns yellow-green within 20 minutes; the mass ratio of cesium to lead is 30:4. Centrifuge, dry, and grind to obtain CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters.

[0044] Figure 1 The CeO prepared in Example 1 of the present invention 2 / Cs 4 PbB 6 Optical photos of the luminescent nanoclusters taken with a digital camera after grinding, where (a) CeO 2 / Cs 4 PbB 6 Optical photograph of luminescent nanocluster powder, (b) CeO 2 / Cs 4 PbB 6 Optical photograph of luminescent nanocluster powder under 365 nm ultraviolet light. Figure 1 It can be seen that CeO 2 / Cs 4 PbB 6 Optical photograph of luminescent nanocluster powder, which is yellow-green in color; it emits bright green fluorescence under 365-nanometer ultraviolet light.

[0045] Figure 2 The CeO prepared in Example 1 of the present invention 2 / Cs 4 PbB 6 The fluorescence spectra and fluorescence quantum efficiency of the luminescent nanoclusters were measured using an Edinburgh FLS980 steady-state fluorescence spectrometer. Figure 2 It can be seen that CeO 2 / Cs 4 PbB6 The luminescent nanocluster has an emission peak at around 520 nanometers, and its absolute fluorescence quantum yield is 34%, indicating that the product CeO 2 / Cs 4 PbB 6 The luminescent nanoclusters have excellent fluorescence properties.

[0046] Figure 3 The CeO prepared in Example 1 of the present invention 2 / Cs 4 PbB 6 After the luminescent nanoclusters were evenly dispersed on a glass slide, they were tested using a Bruker D8-Advance X-ray diffractometer to obtain the X-ray diffraction (XRD) pattern. Figure 3 It can be seen that CeO 2 / Cs 4 PbB 6 The X-ray diffraction peak position of the luminescent nanoclusters is related to the Cs 4 PbB 6 (JCPDS Card No.73-2478), CeO 2 (JCPDS card No.75-0390) standard spectrum, indicating that Cs 4 PbB 6 and CeO 2 of composite nanomaterials.

[0047] Figure 4 The CeO prepared in Example 1 of the present invention 2 / Cs 4 PbB 6 Transmission electron microscopy (TEM) images of luminescent nanoclusters observed with a JEOL-1400 transmission electron microscope. Figure 4 It can be seen that CeO 2 / Cs 4 PbB 6 The luminescent nanoclusters are uniform in size and well dispersed.

[0048] Figure 7 The CeO prepared in Example 1 of the present invention under 365 nm ultraviolet light irradiation 2 / Cs 4 PbB 6 Optical photos of the luminescent nanoclusters taken with a digital camera after being gradually heated from room temperature to 180°C and then returned to room temperature. The samples were placed at different temperatures for 5 minutes. Figure 7 It can be seen that at room temperature, the prepared CeO 2 / Cs 4 PbB 6The luminescent nanoclusters emit bright green fluorescence. As the temperature increases, the prepared CeO 2 / Cs 4 PbB 6 The fluorescence emitted by the luminescent nanoclusters became weaker and weaker, and after the room temperature reached 180 degrees Celsius, the emitted fluorescence was almost completely quenched. But very interestingly, when the sample temperature gradually returned to room temperature, its fluorescence emitted under 365-nanometer ultraviolet light also recovered.

[0049] Figure 8 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 Fluorescence spectra of luminescent nanoclusters at different temperatures. Figure 8 It can be seen that at 70°C, the fluorescence intensity of the sample decreased to 73% of room temperature, at 100°C, the fluorescence intensity of the sample decreased to 51% of room temperature, at 150°C, the fluorescence intensity of the sample decreased to 19% of room temperature, and at 180°C, the fluorescence intensity of the sample decreased to 7% of room temperature. Figure 7 The results were consistent when the samples were irradiated with 365 nm UV light.

[0050] Fig. 9 is CeO in Example 1 of the present invention 2 / Cs 4 PbB 6 The fluorescence spectra of the luminescent nanoclusters at room temperature and after being heated to 180 degrees Celsius and gradually returning to room temperature. Fig. 9 It can be seen that when the sample returns to room temperature, its optical properties remain almost unchanged. Figure 7 The results were consistent when the samples were irradiated with 365 nm UV light.

[0051] Example 2

[0052] (1) Accurately weigh 0.434 g of cerium nitrate hexahydrate and 0.852 g of cesium bromide, add them to 5 mL of deionized water, stir them thoroughly to dissolve, and obtain a mixed aqueous solution. Place the mixed aqueous solution in a refrigerator, freeze it completely, and then freeze-dry it using a vacuum freeze dryer to obtain a freeze-dried powder; wherein the mass ratio of cerium to cesium is 1:4. After fully grinding the freeze-dried powder, calcine it at 300°C for 2.5 hours, cool it to room temperature, and grind it to obtain a calcined powder.

[0053] (2) Accurately weigh 2.753 g of lead bromide and add it to 15 mL of N,N-dimethylformamide. Mix thoroughly to obtain a lead bromide solution in N,N-dimethylformamide.

[0054] (3) Weigh 0.2 g of the calcined powder, add 160 μL of lead bromide N,N-dimethylformamide solution and 90 μL of N,N-dimethylformamide, stir thoroughly to obtain a mixed solution, which turns yellow-green within 20 minutes; the mass ratio of cesium to lead is 30:3. Centrifuge, dry, and grind to obtain CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters.

[0055] Figure 5 The CeO prepared in Example 2 of the present invention 2 / Cs 4 PbB 6 Transmission electron microscope (TEM) photos of nanoluminescent clusters observed with a JEOL-1400 transmission electron microscope. Figure 5 It can be seen that CeO 2 / Cs 4 PbB 6 The luminescent nanoclusters are uniform in size and well dispersed.

[0056] Example 3

[0057] (1) Accurately weigh 0.694 g of cerium nitrate hexahydrate and 1.363 g of cesium bromide, add them to 8 mL of deionized water, stir them thoroughly to dissolve, and obtain a mixed aqueous solution. Place the mixed aqueous solution in a refrigerator, freeze it completely, and then freeze-dry it using a vacuum freeze dryer to obtain a freeze-dried powder; wherein the mass ratio of cerium to cesium is 1:4. After fully grinding the freeze-dried powder, calcine it at 200°C for 3 hours, cool it to room temperature, and grind it to obtain a calcined powder.

[0058] (2) Accurately weigh 1.468 g of lead bromide and add it to 8 mL of N,N-dimethylformamide. Mix thoroughly to obtain a lead bromide solution in N,N-dimethylformamide.

[0059] (3) Weigh 0.2 g of the calcined powder, add 107 μL of N,N-dimethylformamide solution of lead bromide and 143 μL of N,N-dimethylformamide, stir thoroughly to obtain a mixed solution, which turns yellow-green within 20 minutes; the mass ratio of cesium to lead is 30:2. Centrifuge, dry, and grind to obtain CeO 2 / Cs 4 PbB 6 Luminescent nanoclusters.

[0060] Figure 6 The CeO prepared in Example 3 of the present invention 2 / Cs 4 PbB 6Transmission electron microscopy (TEM) images of luminescent nanoclusters observed with a JEOL-1400 transmission electron microscope. Figure 6 It can be seen that CeO 2 / Cs 4 PbB 6 The luminescent nanoclusters are uniform in size and well dispersed.

[0061] According to previous reports, Cs 4 PbB 6 Perovskite materials are different from traditional CsPbBr 3 Perovskite materials, Cs 4 PbB 6 Perovskite materials are based on PbBr 6 4- Octahedron is the basic structural unit, but the octahedrons are not connected to each other, and cesium ions are interspersed among them, which is called zero-dimensional perovskite material. 4 PbB 6 The zero-dimensional perovskite luminescent material is fixed in the cerium dioxide carrier to form CeO 2 / Cs 4 PbB 6 After the luminescent nanoclusters are heated, the structure of the cerium dioxide carrier does not change significantly due to its good stability and high mechanical strength, while the Cs 4 PbB 6 The perovskite crystal structure will be destroyed, and the luminescent nanoclusters will show different fluorescence intensities under different temperature conditions after heating. 4 PbB 6 The particularity of the structure of perovskite materials is Cs 4 PbB 6 The structure of perovskite material is zero-dimensional perovskite and its crystal type is ionic crystal. In addition, the confinement and fixation of the cerium dioxide carrier can effectively reduce the size of the Cs 4 PbB 6 The perovskite crystal structure will gradually recover, and its macroscopic performance is that the fluorescence intensity is restored to the original state. Therefore, the present invention provides a CeO 2 / Cs 4 PbB 6 The method for preparing luminescent nanoclusters can restore the optical properties of the prepared samples after being heated at 180°C.

[0062] Obviously, those skilled in the art can 2 / Cs 4 PbB 6The luminescent nanoclusters and the preparation methods thereof may be modified and altered in various ways without departing from the spirit and scope of the present invention. If these modifications and alterations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these modifications and alterations.

Claims

1. A CeO2 / Cs4PbBr6 luminescent nanocluster whose fluorescence intensity is regulated by temperature, characterized in that: The luminescent nanocluster is composed of a CeO2 carrier and a Cs4PbBr6 luminescent material, wherein the molar ratio of the cerium element to the cesium element is 1:4; and the molar ratio of the cesium element to the lead element is 30:(2-6).

2. The CeO2 / Cs4PbBr6 luminescent nanocluster with fluorescence intensity regulated by temperature according to claim 1, characterized in that: The particle size of the luminescent nanocluster is 20-100 nanometers; it has a fluorescence emission peak at 520 nm, and an absolute fluorescence quantum yield of 34%.

3. The CeO2 / Cs4PbBr6 luminescent nanocluster with fluorescence intensity regulated by temperature according to claim 1, characterized in that: The luminescent nanocluster has the following fluorescence intensity characteristics at different temperatures: the fluorescence intensity at 70°C is 73% of that at room temperature; the fluorescence intensity at 100°C is 51% of that at room temperature; the fluorescence intensity at 150°C is 19% of that at room temperature; the fluorescence intensity at 180°C is 7% of that at room temperature; and the initial fluorescence intensity can be restored after cooling from 180°C to room temperature.

4. A method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as described in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) mixing cerium nitrate hexahydrate, cesium bromide and ionized water, freeze-drying to obtain a lyophilized powder, and grinding and calcining the lyophilized powder to obtain a solid powder; (2) mixing lead bromide with N,N-dimethylformamide to obtain an N,N-dimethylformamide solution of lead bromide; (3) The solid powder, the N,N-dimethylformamide solution of lead bromide and N,N-dimethylformamide are mixed to obtain a mixed solution; and the mixed solution is centrifuged, dried and ground to obtain CeO2 / Cs4PbBr6 luminescent nanoclusters.

5. The method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as claimed in claim 4, characterized in that: In the step (1), the molar ratio of cerium nitrate to cesium bromide is 1:(3.5-4.5); The freeze drying temperature is -55 to -65°C and the time is 40 to 50 hours; The calcination temperature is 200-300° C. and the calcination time is 1-5 hours.

6. The method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as claimed in claim 5, characterized in that: In the step (1), the molar ratio of cerium nitrate to cesium bromide is 1:4; The freeze drying temperature is -60°C and the time is 48h; The calcination temperature is 250° C. and the calcination time is 2 h.

7. The method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as claimed in claim 4, characterized in that: In the step (2), the mixing ratio of lead bromide to N,N-dimethylformamide is (0.1-0.2) g:1 mL.

8. The method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as claimed in claim 7, characterized in that: In the step (2), the mixing ratio of lead bromide to N,N-dimethylformamide is 0.1835 g:1 mL.

9. The method for preparing CeO2 / Cs4PbBr6 luminescent nanoclusters with fluorescence intensity regulated by temperature as claimed in claim 4, characterized in that: In the step (3), the mixing ratio of the solid powder, the N,N-dimethylformamide solution of lead bromide and N,N-dimethylformamide is: 0.2 g: (100-220) μL: (30-150) μL.

10. Application of the CeO2 / Cs4PbBr6 luminescent nanocluster with fluorescence intensity regulated by temperature as claimed in any one of claims 1 to 3 in display, lighting, light-emitting diodes, photodetectors and anti-counterfeiting codes.

Images