CN113480996A

CN113480996A - Crystalline state hydroxide coated perovskite nanocrystalline and preparation method and application thereof

Info

Publication number: CN113480996A
Application number: CN202110928672.9A
Authority: CN
Inventors: 徐庶; 赵森; 张新素; 耿翀
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2021-08-13
Filing date: 2021-08-13
Publication date: 2021-10-08
Anticipated expiration: 2041-08-13
Also published as: CN113480996B

Abstract

The invention relates to a crystalline hydroxide coated perovskite nanocrystalline and a preparation method and application thereof, wherein the crystalline hydroxide contains non-lead metal hydroxide, and the content of total hydroxide in the hydroxide coated perovskite nanocrystalline is 1-99 wt%. According to the invention, the crystalline non-lead hydroxide is formed by wrapping the surface of the nanocrystal, and compared with the amorphous oxide wrapping and the lead-containing hydroxide wrapping, the crystalline non-lead hydroxide has better water oxygen barrier property, luminous efficiency and heat resistance. In the preparation method, the aqueous polar solvent is used as the synthetic solvent, and the wrapping process and the synthetic process are synchronously carried out by slowly adjusting acid-base balance, so that the chemical damage to the surface of the nanocrystal caused by the secondary wrapping process is avoided. And the polar solution environment is favorable for regulating and controlling the dissociation balance of precursor ions, ligand ions can more effectively passivate the surface of the nanocrystal, and the luminous efficiency of the nanocrystal is improved.

Description

Crystalline state hydroxide coated perovskite nanocrystalline and preparation method and application thereof

Technical Field

The invention relates to the technical field of optical materials, in particular to a crystalline hydroxide coated perovskite nanocrystal, a preparation method thereof and a semiconductor luminescent material comprising the crystalline hydroxide coated perovskite nanocrystal.

Background

Perovskite nanocrystals have excellent optical characteristics such as high quantum efficiency, high color purity, and narrow emission half-value width, and thus have been a research focus in the field of display and illumination in recent years. However, the perovskite material has poor environmental stability, and is easily decomposed under the conditions of moisture, air, high temperature and the like to trigger fluorescence quenching, so that the perovskite material loses the luminescence property in the packaging application environment. Therefore, the perovskite nanocrystals are usually wrapped secondarily to isolate them from the external environment, so as to improve their environmental stability. The following three materials are mainly adopted for wrapping: (1) an organic macromolecule or a polymer. However, the polarity difference between the organic matter and the perovskite material is large, phase separation is easy to occur after the coating, and the perovskite agglomeration separation can cause spectrum shift and reduction of luminous efficiency. (2) Inorganic oxide, which is mainly wrapped by a sol-gel method. However, the coating layer is usually in an amorphous state, and pores exist on the surface, so that water and oxygen cannot be fully blocked, and in addition, the coating process can cause chemical damage to the surface of the nanocrystal, and the fluorescence efficiency of the material is reduced. (3) Inorganic salts, mainly sodium salt, potassium salt and Cs₄PbBr₆And the like. However, the inorganic salts are easy to absorb moisture and are very soluble in water, the wrapping material is degraded in a high-humidity environment, and water molecules are transferred to the surface of the nano-crystal to initiate perovskite decomposition. (4) Hydroxide, PbOHBr, Pb (OH) produced by perovskite nanocrystals spontaneously in water₂The lead-containing hydroxide coating layer has good water oxygen barrier capability, but gradually turns yellow at the temperature higher than 70 ℃, so that the luminous efficiency of the perovskite nanocrystal is remarkably reduced. Therefore, the improvement of the stability of the perovskite nanocrystal in a high-temperature and high-humidity environment by growing the stable lead-free crystalline hydroxide coating has urgent practical significance.

Disclosure of Invention

The invention aims to provide a perovskite nanocrystal coated by crystalline hydroxide, a preparation method thereof and a semiconductor luminescent material comprising the perovskite nanocrystal.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a crystalline hydroxide coated perovskite nanocrystal is characterized in that the crystalline hydroxide contains non-lead metal hydroxide, and the content of total hydroxide in the hydroxide coated perovskite nanocrystal is 1-99 wt%.

The crystalline hydroxide comprises non-lead metal hydroxide and lead-containing metal hydroxide, the lead-containing metal hydroxide comprises one of lead bromide hydroxide, lead chloride hydroxide, lead bromide chloride hydroxide and lead hydroxide, the non-lead metal hydroxide comprises one or more of magnesium hydroxide, aluminum hydroxide, zinc hydroxide, zirconium hydroxide, antimony hydroxide, beryllium hydroxide, chromium hydroxide and titanium hydroxide, and the content of the total hydroxide in the crystalline hydroxide coated perovskite nanocrystal is 1-99 wt%, preferably 10-99 wt%. Wherein the ratio of the non-lead metal hydroxide in the total hydroxide is 2 to 100 wt%. The non-lead metal hydroxide is a colorless transparent optical material, can transmit light under visible light, and has better stability and crystal compactness.

And growing silicon oxide on the surface of the perovskite nanocrystalline coated by the crystalline state hydroxide to form the perovskite nanocrystalline coated by the amorphous silicon oxide-crystalline state hydroxide together. Wherein the content of the silicon oxide in the perovskite nanocrystalline coated by the amorphous silicon oxide-crystalline hydroxide is 1-99 wt%, and the coating thickness is 0.5-100nm, preferably 1-10 nm.

The perovskite nanocrystalline is non-core-shell structure nanocrystalline or core-shell structure nanocrystalline.

The non-core-shell structure nanocrystal comprises a ternary structure nanocrystal, a quaternary structure nanocrystal, a ternary structure nanocrystal containing a doped element or a quaternary structure nanocrystal containing a doped element;

the ternary structure nanocrystal is A1A2X1, wherein A1 and A2 are respectively one of methylamino, carbamimidoyl, cesium, lead, sodium, potassium, zirconium, bismuth, copper, tin, silver, rubidium or germanium, A1 is different from A2, and X1 is one of fluorine, chlorine, bromine and iodine;

the quaternary structure nanocrystal is A1A2A3X2, wherein A1, A2 and A3 are respectively one of methylamino, carbamimidoyl, lead, cesium, potassium, sodium, zirconium, copper, tin, silver or bismuth, A1, A2 and A3 are different, and X2 is one of fluorine, chlorine, bromine and iodine;

the doping elements comprise manganese, copper, cerium, europium, zinc, aluminum, bismuth, silver, indium, boron, zirconium, titanium, chromium or cobalt and the like.

The core-shell structure nanocrystal comprises a common core-shell structure nanocrystal and a core-shell structure nanocrystal containing a doped element;

the common core-shell structure nanocrystal comprises a core nanocrystal and a shell material, wherein the core nanocrystal is a non-core-shell structure nanocrystal and comprises a ternary structure nanocrystal or a quaternary structure nanocrystal, and the shell material takes the binary, ternary or quaternary structure nanocrystal as a main body and comprises a II-V group semiconductor material, a perovskite type semiconductor material or an oxide semiconductor and the like;

the core-shell structure nanocrystal containing the doping elements is positioned in the core nanocrystal or the shell material or in the core nanocrystal and the shell material simultaneously, and the doping elements comprise manganese, copper, cerium, europium, zinc, bismuth, silver, indium, boron, zirconium, titanium, chromium or cobalt and the like.

A preparation method of perovskite nanocrystalline coated by crystalline hydroxide comprises the following steps:

(a) adding a first precursor, a second precursor, an amine ligand, a strong acid and a precursor of a metal corresponding to a hydroxide into an aqueous polar solvent; slowly adding alkalescent substances to slowly regulate the system from acidity to neutrality or alkalinity, and synchronously performing a wrapping process and a synthesis process in the acid-base balance regulation process; slowly adding a weakly alkaline substance to replace the conventional method of adjusting acid-base balance by using a strong alkaline substance such as strong alkali, ammonia water and the like, so that the adjusting process is slowly carried out to obtain a crystalline state hydroxide, the pH value of the acid-base adjusting end point is 7-10, the perovskite is synthesized under the acidic condition in the adjusting process, the hydroxide coating is generated under the alkaline condition, the two reaction processes are synchronously completed in the same system, and the chemical damage to the surface of the nanocrystal caused by the secondary coating process is avoided;

(b) continuously stirring the solution obtained in step (a) until a luminescent precipitate is produced;

(c) and centrifuging the precipitate, and drying under vacuum or heating condition to obtain the crystalline hydroxide coated perovskite nanocrystal.

Further, the molecular formula of the first precursor is AX, AX2 or AX3, wherein:

a is metal ion, X is any one or mixture of several of halogen ion or acid radical ion;

preferably, the metal ion comprises Pb²⁺、Zr²⁺、Sn²⁺、Cu⁺、Cu²⁺、Ag⁺Or Bi³⁺Any one or a mixture of several of them, and the halogen ion includes Cl^-、Br^-Or I^-Any one or a mixture of more of them, and the acid radical ion includes SO₄ ^2-、PO₃ ^2-、PO₄ ^3-Or NO₃ ^-Any one or a mixture of several of them.

Further, the molecular structure of the second precursor is BX, wherein:

b is amine organic group or metal ion, X is any one or mixture of halogen ion or acid radical ion;

preferably, the amine organic group comprises one or more of methylamino or amidino, and the metal ion comprises Cs⁺、K⁺、Na⁺、Rb⁺Any one or a mixture of several of them, and the halogen ion includes Cl^-、Br^-Or I^-Any one or a mixture of more of them, and the acid radical ion includes SO₄ ^2-、PO₃ ^2-、PO₄ ^3-Or NO₃ ^-Any one or a mixture of several of them.

Further, the amino ligand is an amino acid ligand, and comprises any one or mixture of glycine, phenylalanine, aspartic acid, lysine, glutamic acid, arginine, alanine, leucine, proline, serine and tyrosine;

preferably, the amino acid ligand comprises any one or a mixture of phenylalanine, aspartic acid, glycine or arginine.

Further, the amine ligand is water-soluble organic amine or amine salt, and comprises one or a mixture of several of methylamine, ethylamine, propylamine, butylamine, hexylamine, dibutylamine, tetrabutylammonium bromide, triethanolamine, diisopropylamine, ethylenediamine, tetrahydropyrrole and the like.

Further, the strong acid comprises any one or a mixture of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid or phosphoric acid.

Further, the structure of the precursor of the corresponding metal of the hydroxide is CX, wherein:

c is metal corresponding to hydroxide, X is any one or mixture of halogen ion or acid radical ion;

preferably, the metal corresponding to the hydroxide comprises any one or a composite of several of lead, magnesium, aluminum, zinc, zirconium, antimony, beryllium or chromium, and the halogen ions comprise Cl^-、Br^-Or I^-Any one or a mixture of more of them, and the acid radical ion includes SO₄ ^2-、PO₃ ^2-、PO₄ ^3-Or NO₃ ^-Any one or a mixture of several of them.

Further, the alkalescent substance comprises any one or a mixture of more of methylamine water solution, methylamine ethanol solution, imidazole substance, urea, pyridine or pyrrole; the pH value of the acid-base balance regulation end point is 7-10, and the dripping speed of the weakly alkaline substance is 10-2000 uL/min; the temperature under vacuum is 20-150 ℃.

Furthermore, the imidazole substance comprises any one or a mixture of several of 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole and 4-methylimidazole.

Further, the aqueous polar solvent comprises one or a mixture of ethanol, propanol, butanol, N-dimethylformamide or dimethyl sulfoxide, and the content of water in the aqueous polar solvent is 20-100 wt%, preferably 50-100 wt%.

Further, the temperature of the vacuum condition is 20-150 ℃.

Coating silicon oxide outside the crystalline state hydroxide coated perovskite nanocrystalline comprises the following steps:

(1) dispersing the hydroxide-coated perovskite nanocrystal into deionized water or aqueous polar solution, adding a silicon oxide precursor, stirring in air for reaction, and gradually coating and growing silicon oxide on the surface of the hydroxide.

(2) And centrifuging the precipitate, washing the precipitate by deionized water, and drying the precipitate under the condition of vacuum or heating (80-120 ℃) to obtain the perovskite nanocrystalline powder coated by the silicon oxide-crystalline hydroxide.

Further, the silicon oxide precursor is silicate ester compound, and comprises one or more of methyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), 3-Aminopropyltriethoxysilane (APTES) and the like.

Further, the reaction time for coating the silicon oxide is 0.5 to 50 hours, preferably 1 to 8 hours.

Further, the thickness of the silicon oxide wrapping layer is 0.5-100nm, preferably 1-10 nm.

The invention also provides a semiconductor luminescent material which comprises the crystalline hydroxide coated perovskite nanocrystal and the silicon oxide-crystalline hydroxide coated perovskite nanocrystal.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, the crystalline non-lead hydroxide is formed by wrapping the surface of the nanocrystal, and compared with the amorphous oxide wrapping and the lead-containing hydroxide wrapping, the crystalline non-lead hydroxide has better water oxygen barrier property, luminous efficiency and heat resistance.

2. According to the preparation method, the aqueous polar solvent is used as the synthetic solvent, the wrapping process and the synthetic process are synchronously carried out by slowly adjusting acid-base balance, and the chemical damage to the surface of the nanocrystal caused by the secondary wrapping process is avoided. And the polar solution environment is favorable for regulating and controlling the dissociation balance of precursor ions, ligand ions can more effectively passivate the surface of the nanocrystal, and the luminous efficiency of the nanocrystal is improved.

3. The crystalline state hydroxide coated perovskite nanocrystalline prepared by the invention contains a plurality of types of crystalline state hydroxides, and the hydroxide coating material is insoluble in water, is difficult to dissociate in water and is difficult to absorb moisture, so that the corrosion of water vapor and air to quantum dots can be effectively prevented, and the environmental stability of the nanocrystalline is remarkably improved.

4. According to the silicon oxide-crystalline hydroxide double-coated perovskite nanocrystalline obtained by the invention, on one hand, the silicon oxide and hydroxide coating material is insoluble in water, is difficult to dissociate in water and is difficult to absorb moisture, so that the corrosion of water vapor and air to the perovskite nanocrystalline can be effectively prevented, and the environmental stability of the nanocrystalline is remarkably improved. On the other hand, the silica coating can effectively inhibit the decomposition of the hydroxide coating layer, thereby further enhancing the stability of the material under heating and drying conditions. Amorphous silicon oxide is more advantageous for later optical applications and may be present in the form of SiOx.

Drawings

FIG. 1 shows CH (NH) coated with zinc hydroxide/lead hydroxide chlorobromide₂)₂PbClBr₂A nanocrystalline TEM photograph, wherein the right image is an enlarged view of a region in the left image;

FIG. 2 is a schematic representation of aluminum hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃Photograph of nanocrystalline powder.

Fig. 3 is a fluorescence spectrum of a zirconium hydroxide/lead hydroxide bromine-coated CH3NH3PbBr3 nanocrystal.

FIG. 4 shows CsPbBr coated with zinc hydroxide/lead hydroxide bromide₃Photograph of the nanocrystal aqueous solution.

FIG. 5 shows CsPbBr coated with zinc hydroxide/lead hydroxide bromide₃And (4) nanocrystalline XRD pictures.

FIG. 6 Zinc hydroxide/lead hydroxide bromine coated CsPbBr₃Graph of fluorescence intensity change of nanocrystal at 85 degree and 85 degree humidity.

FIG. 7 shows silica-lead hydroxide bromine coated CH (NH)₂)₂PbBr₃A nanocrystalline TEM image, wherein b is a partial enlarged view of a picture a;

FIG. 8 shows silica-alumina hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃A fluorescence spectrum of the nanocrystal;

FIG. 9 shows silica-Zinc hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃Powder photo of the nanocrystal;

FIG. 10 shows CsPbClBr coated with silica-zirconium hydroxide/lead bromide₂A photograph of the nanocrystal aqueous solution;

FIG. 11 shows silica-Zinc hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃A fluorescence intensity change curve chart of the nanocrystalline under 85 degrees and 85 humidities;

FIG. 12 shows PbOHBr-coated CH obtained in comparative example 3₃NH₃PbBr₃Luminescence spectrum and quantum efficiency before and after heating and drying of the nanocrystal.

Detailed Description

The present invention is described in detail below with reference to the following examples and drawings, but the present invention is not limited thereto.

Example 1

This example illustrates the preparation of zinc hydroxide/lead hydroxide chlorobromide coated CH (NH)₂)₂PbClBr₂Example of nanocrystals

1mmol of PbBr₂、1mmol ZnBr₂1mmol of formamidine hydrochloride CH (NH)₂)₂Mixing Cl, 1mmol of phenylalanine, 0.5mL of HCl aqueous solution (20 wt% concentration) and 1mL of HBr aqueous solution (20 wt% concentration) to dissolve the mixture into a clear solution, adding the clear solution into 5mL of a mixed solution of ethanol and water, wherein the mass fraction ratio of ethanol to water in the mixed solution is 1:1, and dropwise adding a 5 wt% methylamine aqueous solution at a speed of one drop per second under slow stirring until the pH value is 8; continuously stirring the solution for 4 hours to obtain blue-green luminescent precipitate; centrifuging the precipitate, and vacuum-treating at room temperatureThen, drying treatment is performed.

The zinc hydroxide/lead hydroxide chlorobromide coated CH (NH) prepared in this example₂)₂PbClBr₂The TEM photograph of the nanocrystals is shown in FIG. 1, and it can be seen from FIG. 1 that the obtained product is uniformly dispersed nanocrystalline particles with a size of 20-70 nm.

Example 2

This example prepares aluminum hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃Example of nanocrystals

1mmol of Pb (NO)₃)₂、1mmol CH₃NH₃Br₃1mmol of aspartic acid and 1mmol of AlBr₃1ml of aqueous HBr (20 wt% concentration) is mixed to obtain a clear solution, the clear solution is added into a mixed solution of 5ml of ethanol and water, wherein the mass fraction ratio of the ethanol to the water is 1:1, and after the mixture is uniformly mixed, 1 mol/L of 2-methylimidazole aqueous solution is slowly and dropwise added under stirring until the pH value is 9; continuously stirring the solution for 4 hours to obtain green luminous precipitate; the precipitate was centrifuged and dried under vacuum at room temperature.

Crystalline aluminum hydroxide/lead bromide hydroxide coated CH prepared in this example₃NH₃PbBr₃The photograph of the nanocrystalline powder is shown in FIG. 2. it can be seen from FIG. 2 that crystalline hydroxide-coated CH₃NH₃PbBr₃The nanocrystalline is in a uniform powder state and is in a yellow-green color under sunlight.

Example 3

This example prepares zirconium hydroxide/lead hydroxide bromine coated CH₃NH₃PbClBr₂Example of nanocrystals

1mmol of PbCl₂、1mmol CH₃NH₃Br₃、1mmol ZrBr₂2mmol of aspartic acid, 1ml of aqueous HBr (20% strength by weight) are added to 5ml of water, and 5 w% aqueous methylamine solution is added dropwise at a rate of one drop per second with slow stirring to a pH of 8; continuously stirring for 4 hours to generate blue-green luminous precipitate; the precipitate was centrifuged and dried under vacuum at room temperature.

This examplePrepared zirconium hydroxide/lead hydroxide bromine-coated CH₃NH₃PbClBr₂The nanocrystal aqueous solution is yellow green under the irradiation of blue light, the fluorescence spectrum of the nanocrystal aqueous solution is shown in figure 3, and as can be seen from figure 3, the crystalline hydroxide coated CH₃NH₃PbClBr₂The half-peak width of the nanocrystal is 27nm, and the characteristics of uniform nanocrystal size distribution and high growth controllability are shown.

Example 4

This example was carried out to prepare zinc hydroxide/lead hydroxide bromine-coated CsPbBr₃Example of nanocrystals

1mmol of PbBr₂1mmol CsBr, 1mmol glycine, 1ml aqueous HBr solution (20% strength by weight), 1mmol ZnBr₂Adding the mixture into 5ml of water; slowly stirring and dropwise adding 1 mol/L2-methylimidazole water solution to the pH value of 9; continuously stirring for 4 hours to generate blue-green luminous precipitate; the precipitate was centrifuged and dried under vacuum at room temperature.

The zinc hydroxide/lead hydroxide bromine-coated CsPbBr prepared in this example₃The nanocrystal aqueous solution appeared green in sunlight, as shown in fig. 4, and as can be seen from fig. 4, the hydroxide-coated CsPbBr₃The nano crystal has higher fluorescence efficiency, and the quantum yield is 85% after the test. FIG. 5 shows CsPbBr coated with zinc hydroxide/lead hydroxide bromide₃The XRD pattern of the nanocrystal shows that obvious zinc hydroxide, lead bromide hydroxide and CsPbBr are present₃The corresponding characteristic peak indicates that the CsPbBr coated by the crystalline composite hydroxide is obtained₃And (4) nanocrystals.

Example 5

For the zinc hydroxide/lead hydroxide bromine coated CsPbBr prepared in example 4₃And (3) carrying out photostability test on the nanocrystals:

hydroxide-coated CsPbBr₃And adding the nanocrystalline into the same amount of ultraviolet curing silica gel, dropwise adding the nanocrystalline onto the surface of an LED blue light chip with the light-emitting wavelength of 450nm by using a dispenser, and performing ultraviolet curing. Lightening an LED blue light chip and keeping the power density of the LED blue light chip at 1W/cm²Continuously recording the change of fluorescence intensity by using a fluorescence spectrometer to obtain a fluorescence peakThe ratio of the intensity to the initial fluorescence peak intensity is plotted as an intensity-time decay curve. FIG. 6 shows a hydroxide coated CsPbBr₃Light attenuation plot of nanocrystals. As can be seen from FIG. 6, the relative luminescence intensity did not change much, and the crystalline zinc hydroxide/lead hydroxide bromine-coated CsPbBr was obtained₃The nanocrystalline has high stability under the condition of 85 degrees/85 humidity.

Example 6

This example prepared silica-Zinc hydroxide/lead hydroxide bromine coated CH (NH)₂)₂PbBr₃Example of nanocrystals

Centrifuging the nanocrystal precipitate obtained in example 4, re-dispersing into a mixed solution of deionized water and ethanol (water-alcohol ratio of 1:9), adding 10ul TMOS, and stirring in air for 8 hours; the precipitate was centrifuged and dried under 80 ℃ vacuum to give a green powder.

silica-Zinc hydroxide/lead Bromide coated CH prepared in this example₃NH₃PbBr₃The nanocrystalline aqueous solution appeared green in sunlight, and as can be seen from fig. 7, the silica-zinc hydroxide coated CH₃NH₃PbBr₃The nanocrystals are in a uniform powder state (left image in fig. 7), appear yellow green under sunlight (right image in fig. 7), have high fluorescence efficiency, and have a quantum yield of 92% after being tested. Silica-crystalline zinc hydroxide/lead bromide hydroxide coated CH (NH)₂)₂PbBr₃The TEM photograph of the nanocrystals is shown in fig. 8, which shows that the silicon oxide is coated on the surface of the nanocrystals and grows into an interconnected composite structure.

Example 7

This example prepared silica-alumina hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃Example of nanocrystals

Centrifuging the nanocrystal precipitate in example 2, re-dispersing into deionized water, adding 20ul TMOS, and stirring in air for 8 hours; the precipitate was centrifuged and dried under 80 ℃ vacuum to give a green powder.

Silica-alumina hydroxide/lead hydroxide bromine coated CH prepared in this example₃NH₃PbBr₃The luminescence spectrum of the nanocrystalline powder is shown in FIG. 9, and the silica-crystalline hydroxide-coated CH₃NH₃PbBr₃The luminescence of the nanocrystal is about 550nm, the nanocrystal has narrower luminescence broadening, the half-peak width is 27nm, and the characteristics of uniform size distribution and high growth controllability of the nanocrystal are shown.

Example 8

This example was carried out to prepare a silica-crystalline zirconium hydroxide/lead hydroxide bromine-coated CsPbClBr₂Example of nanocrystals

1mmol of PbCl₂、1mmol CsBr₃2mmol of aspartic acid, 1ml of HBr, 1mmol of ZrBr₂Adding the mixture into 5ml of water, and slowly adding a methylamine water solution until the mixture is alkaline; continuously stirring for 4 hours to generate blue-green luminous precipitate; centrifuging the precipitate, re-dispersing in ethanol, adding 10ul TMOS, and stirring in air for 4 hr; the precipitate was centrifuged and dried under vacuum to give a green powder.

The silica-crystalline zirconium hydroxide/lead hydroxide bromine-coated CsPbClBr prepared in this example₂The nanocrystal aqueous solution appears yellow green under the irradiation of blue light, as shown in fig. 10, it can be seen that it has high luminous efficiency and luminous stability in water.

Example 9

Silica-crystalline Zinc hydroxide/lead Bromide coated CH prepared in example 6₃NH₃PbBr₃Testing the photostability of the nanocrystals

Silica-crystalline hydroxide coated CH₃NH₃PbBr₃And adding the nanocrystalline into the same amount of ultraviolet curing silica gel, dropwise adding the nanocrystalline onto the surface of an LED blue light chip with the light-emitting wavelength of 450nm by using a dispenser, and performing ultraviolet curing. Lightening an LED blue light chip and keeping the power density of the LED blue light chip at 1W/cm²The fluorescence intensity variation is continuously recorded by using a fluorescence spectrometer, and an intensity-time decay curve is drawn by the ratio of the fluorescence peak intensity to the initial fluorescence peak intensity. FIG. 11 shows a hydroxide coated CsPbBr₃Light attenuation diagram of nanocrystalline, in which the abscissa is time and the ordinate isIs the relative intensity. As can be seen from FIG. 11, silica-crystalline zinc hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃The luminescence intensity of the nanocrystal shows a trend of increasing in a test time of 300h under the condition of high temperature and high humidity (the experimental condition in the embodiment is 85 ℃/85 humidity), and the nanocrystal is stabilized at about 1.1 of relative luminescence intensity, and the zinc hydroxide/lead hydroxide bromine coated CH₃NH₃PbBr₃The relative luminescence intensity of the nanocrystals tended to decrease slowly after 50h, indicating that the silica-crystalline hydroxide coated CH₃NH₃PbBr₃The nanocrystal has better luminescence maintenance.

Comparative example 1

The steps and raw materials of this example are the same as example 1, except that methylamine aqueous solution is rapidly added to corresponding pH value, so that the obtained perovskite nanocrystal coated by incomplete hydroxide is obtained. The prepared nanocrystal has low luminous efficiency.

Comparative example 2

Directly in CH₃NH₃PbBr₃Amorphous SiO grows on the surface of the nanocrystalline₂SiO obtained₂The encapsulation efficiency and water stability of the nanocrystal are low.

Comparative example 3

Will CH₃NH₃PbBr₃Soaking the nanocrystalline powder in water, stirring for 1 minute, and centrifuging and precipitating. The procedure of example 1 was repeated to prepare crystalline PbOHBr-coated CH free of lead-free metal hydroxide without adding a zinc source₃NH₃PbBr₃And (4) nanocrystals. The obtained nanocrystals have high efficiency and water stability, but turn yellow under vacuum or heating conditions, resulting in low quantum efficiency. As can be seen from the spectrum and luminous efficiency test of FIG. 12, PbOHBr-coated CH₃NH₃PbBr₃The luminous intensity of the nanocrystalline is reduced by more than 90% after heating.

Finally, the description is as follows: the embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. A crystalline hydroxide coated perovskite nanocrystal is characterized in that the crystalline hydroxide comprises a non-lead metal hydroxide, and the content of the total hydroxide in the hydroxide coated perovskite nanocrystal is 1-99 wt%.

2. A crystalline hydroxide-coated perovskite nanocrystal according to claim 1, wherein the non-lead metal hydroxide is a colorless transparent optical material comprising at least one of magnesium hydroxide, aluminum hydroxide, zinc hydroxide, zirconium hydroxide, antimony hydroxide, beryllium hydroxide, chromium hydroxide, titanium hydroxide; the ratio of the non-lead metal hydroxide in the total hydroxide is 2 to 100 wt%.

3. A crystalline hydroxide coated perovskite nanocrystal as claimed in claim 1, wherein the crystalline hydroxide further comprises a lead-containing metal hydroxide, the lead-containing metal hydroxide comprises one of lead bromide, lead chloride, lead bromide chloride and lead hydroxide, the proportion of the lead-containing metal hydroxide in the total hydroxide is 1-99%, and the content of the total hydroxide in the crystalline hydroxide coated perovskite nanocrystal is 10-99 wt%.

4. The crystalline hydroxide-coated perovskite nanocrystal according to claim 1, wherein silicon oxide is grown on the surface of the crystalline hydroxide-coated perovskite nanocrystal to form an amorphous silicon oxide-crystalline hydroxide co-coated perovskite nanocrystal.

5. A crystalline hydroxide coated perovskite nanocrystal as claimed in claim 4, wherein the content of the silicon oxide in the perovskite nanocrystal coated by the amorphous silicon oxide-crystalline hydroxide together is 1-99 wt%, the coating thickness is 0.5nm-100nm, preferably 1nm-10 nm;

the perovskite nanocrystalline is non-core-shell structure nanocrystalline or core-shell structure nanocrystalline;

the ternary structure nanocrystal is A1A2X1, wherein A1 and A2 are respectively one of methylamino, carbamimidoyl, cesium, lead, bismuth, potassium, sodium, zirconium, bismuth, copper, tin, rubidium or germanium, A1 is different from A2, and X1 is one of fluorine, chlorine, bromine and iodine;

the doping elements comprise manganese, copper, cerium, europium, zinc, bismuth, silver, indium, boron, zirconium, titanium, chromium or cobalt and the like;

6. A preparation method of perovskite nanocrystalline coated by crystalline hydroxide comprises the following steps:

(a) adding a first precursor, a second precursor, an amine ligand, a strong acid and a precursor of a metal corresponding to a hydroxide into an aqueous polar solvent; slowly adding alkalescent substances to enable the system to realize the slow regulation and control from acidity to alkalinity, and realizing the synchronous implementation of the wrapping process and the synthesis process in the acid-base balance regulation and control process;

7. The preparation method according to claim 6, wherein the pH value of the acid-base balance regulation end point is 7-10, and the dropping speed of the weakly alkaline substance is 10-2000 uL/min; the temperature under vacuum is 20-150 ℃.

8. The method of claim 6, wherein the first precursor has a molecular formula of AX, AX2, or AX3, wherein:

preferably, the metal ion comprises Pb²⁺、Zr²⁺、Sn²⁺、Cu⁺、Cu²⁺、Ag⁺Or Bi³⁺Wherein the halogen ion comprises Cl^-、Br^-Or I^-At least one of, the acid radical ion comprises SO₄ ^2-、PO₃ ^2-、PO₄ ^3-Or NO₃ ^-At least one of;

the molecular structure of the second precursor is BX, wherein:

preferably, the amine organic group comprises one or more of methylamino or amidino, and the metal ion comprises Cs⁺、K⁺、Na⁺、Rb⁺The halogen ion comprises any one or a mixture of Cl-, Br-or I-, and the acid radical ion comprises SO₄ ^2-、PO₃ ^2-、PO₄ ^3-Or NO₃ ^-At least one of;

the amino ligand is an amino acid ligand and comprises at least one of glycine, phenylalanine, aspartic acid, lysine, glutamic acid, arginine, alanine, leucine, proline, serine and tyrosine;

the amino ligand is water-soluble organic amine or amine salt, and comprises at least one of methylamine, ethylamine, propylamine, butylamine, hexylamine, dibutylamine, tetrabutylammonium bromide, triethanolamine, diisopropylamine, ethylenediamine, tetrahydropyrrole and the like;

the strong acid comprises at least one of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, or phosphoric acid;

the structure of the precursor of the corresponding metal of the hydroxide is CX, wherein:

The weak alkaline substance comprises at least one of methylamine water solution, methylamine ethanol solution, imidazole substance, urea, pyridine or pyrrole; the imidazole substance comprises at least one of 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole and 4-methylimidazole;

the content of water in the aqueous polar solvent is 20 to 100 wt%, preferably 50 to 100 wt%; the aqueous polar solvent includes at least one of ethanol, propanol, butanol, N-dimethylformamide, or dimethylsulfoxide.

9. The production method according to any one of claims 6 to 8, wherein the step of coating silicon oxide outside the crystalline hydroxide-coated perovskite nanocrystal comprises the steps of:

(1) dispersing the perovskite nano-crystal coated by the crystalline state hydroxide into deionized water or aqueous polar solution, adding a silicon oxide precursor, stirring in air for reaction, and gradually coating and growing silicon oxide on the surface of the crystalline state hydroxide;

(2) centrifuging the precipitate, washing with deionized water, and drying under vacuum or heating (80-120 deg.C) to obtain silicon oxide-crystalline hydroxide coated perovskite nanocrystalline powder;

the silicon oxide precursor is silicate ester compound, and comprises at least one of methyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS) and 3-Aminopropyltriethoxysilane (APTES).

10. A semiconductor light-emitting material comprising the crystalline hydroxide-coated perovskite nanocrystal according to any one of claims 1 to 5 or the crystalline hydroxide-coated perovskite nanocrystal or the silicon oxide-crystalline hydroxide-coated perovskite nanocrystal obtained by the production method according to any one of claims 6 to 8.