Preparation method of red perovskite quantum dots with high thermal stability

Abstract

The invention provides a preparation method of red perovskite quantum dots with high thermal stability. The preparation method comprises the following steps: S1, mixing a perovskite nanocrystalline precursor, an isocyanate precursor and a micro / mesoporous template, and grinding to obtain a mixture; and S2, in an inert atmosphere environment, calcining the mixture obtained in the step S1 at a high temperature of 600-700 DEG C, and then cooling to room temperature to prepare the red perovskite quantum dot with a structural formula of CsPbIxBr3-x, where X is greater than 0 and less than 3. The problem of thermal stability is solved, so that the industrialization requirement of the perovskite quantum dots in the field of light-emitting display is met.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite materials, and in particular relates to a method for preparing red perovskite quantum dots with high thermal stability. Background Art

[0002] The biggest problems with existing red perovskite quantum dots based on bromine-iodine mixed halogens come from two aspects: on the one hand, due to the presence of bromine and iodine components, mixed halogen perovskites are prone to halogen ion migration under external environmental stimuli such as heating and strong light irradiation, resulting in a shift in the luminescence spectrum; on the other hand, there is water and thermal stability.

[0003] Our company's previously applied Chinese patent number ZL 202311251027.3 discloses a red light perovskite material based on bromine-iodine mixed halogen and its preparation method. This method can solve the technical problem of halogen ion migration leading to luminescence spectrum shift. However, the above method does not solve the problem of thermal stability, so it needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing red perovskite quantum dots with high thermal stability, thereby solving the problem of thermal stability and meeting the industrialization needs of perovskite quantum dots in the field of light-emitting display.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing red perovskite quantum dots with high thermal stability, comprising the following steps:

[0006] S1, mixing and grinding a perovskite nanocrystal precursor, an isocyanate precursor and a micro / mesoporous template to obtain a mixture;

[0007] S2. In an inert atmosphere, the mixture obtained in step S1 is calcined at 600-700°C, and then cooled to room temperature to obtain a product having a structural formula of CsPbI x Br 3-x Red perovskite quantum dots, where 0<X<3.

[0008] Furthermore, the isocyanate precursor includes at least one of cyanuric acid, melamine and urea.

[0009] Further, the perovskite nanocrystal precursor includes a Cs source precursor, a Pb source precursor, an I source precursor and a Br source precursor;

[0010] The Cs source precursor is one or more of cesium halide and cesium carbonate;

[0011] The Pb source precursor is one or more of lead halide and lead acetate;

[0012] The I source precursor is one or more of zinc iodide, potassium iodide, sodium iodide, lithium iodide, calcium iodide, strontium iodide, and barium iodide;

[0013] The Br source precursor is one or more of zinc bromide, potassium bromide, sodium bromide, lithium bromide, calcium bromide, strontium bromide and barium bromide.

[0014] Further, the micro / mesoporous template is a microporous material and / or a mesoporous material;

[0015] The microporous material is a microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate or microporous transition metal nitride;

[0016] The mesoporous material is mesoporous molecular sieve, mesoporous silica, mesoporous titania, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate or mesoporous transition metal nitride.

[0017] Furthermore, the method further comprises step S3, post-processing:

[0018] The red perovskite quantum dots prepared in step S2 are washed with deionized water, centrifuged, and dried.

[0019] Furthermore, by adjusting the dosage of the I source precursor, the wavelength of red light emission can be regulated.

[0020] Furthermore, the inert atmosphere is nitrogen, argon and a combination thereof.

[0021] Furthermore, the amount of the isocyanate precursor is 5%-20% of the mass of the micro / mesoporous template.

[0022] Furthermore, the in-situ normalized luminescence intensity of the red perovskite quantum dots can be restored to at least 80% after undergoing a 130° C. heating stage and a cooling stage.

[0023] A red perovskite quantum dot is prepared by the above method.

[0024] The beneficial effects of the present invention are mainly reflected in:

[0025] 1. The cyanuric acid, melamine and urea selected in the present invention all have a common characteristic, that is, they will decompose into isocyanic acid at high temperature. For example, under the high-temperature calcination process of the present application, cyanuric acid is depyrogenic to produce isocyanic acid. In the specific calcination process, cyanuric acid is first heated to volatilize and sublimate into a vapor state. Since cyanuric acid first evaporates and becomes gaseous, the rich pores of the micro / mesoporous template can absorb gaseous cyanuric acid. At this time, the cyanuric acid vapor is further heated to decompose into isocyanic acid. Then, when the temperature is raised and heated to the collapse temperature of the micro / mesoporous template, the micro / mesoporous template begins to gradually collapse, close the pores, and form a shell.

[0026] 2. The present application constructs an isocyanate atmosphere in the shell layer, thereby improving the PLQY and thermal stability of quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an in-situ normalized luminescence intensity diagram of the perovskite quantum dots obtained in Example 1 after undergoing a 130° C. heating stage and a cooling stage;

[0028] Figure 2 This is an in-situ normalized luminescence intensity diagram of the perovskite quantum dots obtained in Example 2 after undergoing a 130° C. heating stage and a cooling stage;

[0029] Figure 3 This is an in-situ normalized luminescence intensity diagram of the perovskite quantum dots obtained in Comparative Example 1 after undergoing a 130°C heating stage and a cooling stage. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Embodiment 1:

[0032] Cb x I 3-x Preparation of @MCM-41 quantum dots: Weigh 0.2mol Cs2CO3, 0.2mol PbBr2, 0.2mol PbI2, 0.01mol ZnBr2, 100g MCM-41, and 8g cyanuric acid, mix them in a wall breaker for 30s, put them into a sintering device, heat them to 630℃ at a heating rate of 18℃ / min under argon atmosphere, keep the temperature at 630℃ for 30min, and cool them naturally to obtain CsPbBr x I 3-x @MCM-41 composite material crude product.

[0033] CsPbBr x I3-x The crude product of @MCM-41 quantum dots was washed twice with deionized water, centrifuged and placed in a 60°C vacuum drying oven for 24 hours to obtain the purified CsPbBr x I 3-x @MCM-41 quantum dots. Figure 1 The thermal stability test diagram of perovskite quantum dots shown in the figure shows that the in-situ normalized luminescence intensity of the quantum dots can be restored to at least 80% after undergoing a 130°C heating stage and a cooling stage.

[0034] Embodiment 2:

[0035] Cb x I 3-x Preparation of @MCM-41 quantum dots: 0.2 mol Cs2CO3, 0.2 mol PbBr2, 0.2 mol PbI2, 0.01 mol ZnBr2, 100 g MCM-41, and 12 g cyanuric acid were weighed and mixed in a wall breaker for 30 seconds. The mixture was put into a sintering device and heated to 630°C at a rate of 18°C / min under an argon atmosphere. The temperature was then kept constant at 630°C for 30 minutes and cooled naturally to obtain CsPbBr x I 3-x @MCM-41 composite material crude product.

[0036] CsPbBr x I 3-x The crude product of @MCM-41 quantum dots was washed twice with deionized water, centrifuged and placed in a 60°C vacuum drying oven for 24 hours to obtain the purified CsPbBr x I 3-x @MCM-41 quantum dots.

[0037] like Figure 2 The thermal stability test diagram of perovskite quantum dots shown in the figure shows that the in-situ normalized luminescence intensity of the quantum dots can be restored to at least 90% after undergoing a 130°C heating stage and a cooling stage.

[0038] Example 3: Urea

[0039] Cb x I 3-x Preparation of @MCM-41 quantum dots: 0.2 mol Cs2CO3, 0.2 mol PbBr2, 0.2 mol PbI2, 0.01 mol ZnBr2, 100 g MCM-41, and 8 g urea were weighed and mixed in a wall breaker for 30 seconds. The mixture was put into a sintering device and heated to 630°C at a rate of 18°C / min under an argon atmosphere. The mixture was then kept at 630°C for 30 minutes and cooled naturally to obtain CsPbBr x I 3-x@MCM-41 composite material crude product.

[0040] CsPbBr x I 3-x The crude product of @MCM-41 quantum dots was washed twice with deionized water, centrifuged and placed in a 60°C vacuum drying oven for 24 hours to obtain the purified CsPbBr x I 3-x @MCM-41 quantum dots.

[0041] Example 4: Melamine

[0042] Cb x I 3-x Preparation of @MCM-41 quantum dots: 0.2 mol Cs2CO3, 0.2 mol PbBr2, 0.2 mol PbI2, 0.01 mol ZnBr2, 100 g MCM-41, and 8 g melamine were weighed and mixed in a wall breaker for 30 seconds. The mixture was taken out and put into a sintering device. The temperature was raised to 630°C at a rate of 18°C / min under an argon atmosphere. The temperature was then kept constant at 630°C for 30 minutes and cooled naturally to obtain CsPbBr x I 3-x @MCM-41 composite material crude product.

[0043] CsPbBr x I 3-x The crude product of @MCM-41 quantum dots was washed twice with deionized water, centrifuged and placed in a 60°C vacuum drying oven for 24 hours to obtain the purified CsPbBr x I 3-x @MCM-41 quantum dots.

[0044] Comparative Example 1:

[0045] The difference from Example 1 is that no cyanuric acid is added.

[0046] like Figure 3 The thermal stability test diagram of perovskite quantum dots shown in the figure shows that the in-situ normalized luminescence intensity of the quantum dots can be restored to 62% after undergoing a 130°C heating stage and a cooling stage.

[0047] The performance characterization data of Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0048]

[0049]

[0050] Table 1

[0051] As can be seen from Table 1, the addition of isocyanate precursors not only improves PLQY and thermal stability, but also has the effect of regulating the emission wavelength. In addition, the reason why the present invention uses isocyanate precursors instead of directly using isocyanate is that, on the one hand, isocyanate cannot exist stably alone at room temperature, and can only be stored for a long time if absorbed in a solvent; on the other hand, isocyanate will decompose and release nitrogen oxide fumes when overheated. The decomposition of isocyanate precursors is an endothermic process in itself, thereby avoiding overheating of isocyanate.

[0052] The embodiments described above provide a detailed description of the preparation scheme of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing red perovskite quantum dots with high thermal stability, characterized in that: The steps include: S1, mixing and grinding a perovskite nanocrystal precursor, an isocyanate precursor and a micro / mesoporous template to obtain a mixture; S2. In an inert atmosphere, the mixture obtained in step S1 is calcined at 600-700°C, and then cooled to room temperature to obtain a product having a structural formula of CsPbI x Br 3-x Red perovskite quantum dots, where 0<X<3.

2. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The isocyanate precursor includes at least one of cyanuric acid, melamine and urea.

3. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The perovskite nanocrystal precursor includes a Cs source precursor, a Pb source precursor, an I source precursor and a Br source precursor; The Cs source precursor is one or more of cesium halide and cesium carbonate; The Pb source precursor is one or more of lead halide and lead acetate; The I source precursor is one or more of zinc iodide, potassium iodide, sodium iodide, lithium iodide, calcium iodide, strontium iodide, and barium iodide; The Br source precursor is one or more of zinc bromide, potassium bromide, sodium bromide, lithium bromide, calcium bromide, strontium bromide and barium bromide.

4. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The micro / mesoporous template is a microporous material and / or a mesoporous material; The microporous material is a microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate or microporous transition metal nitride; The mesoporous material is mesoporous molecular sieve, mesoporous silica, mesoporous titania, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate or mesoporous transition metal nitride.

5. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: It also includes step S3, post-processing: The red perovskite quantum dots prepared in step S2 are washed with deionized water, centrifuged, and dried.

6. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: By adjusting the dosage of the I source precursor, the wavelength of red light emission can be regulated.

7. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The inert atmosphere is nitrogen, argon and a combination thereof.

8. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The amount of the isocyanate precursor is 5%-20% of the mass of the micro / mesoporous template.

9. The method for preparing red perovskite quantum dots with high thermal stability according to claim 1, characterized in that: The in-situ normalized luminescence intensity of the red perovskite quantum dots can be restored to at least 80% after undergoing a 130° C. heating stage and a cooling stage.

10. A red perovskite quantum dot, characterized in that: The method is prepared by any one of claims 1 to 9.

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