Rare earth doped perovskite quantum dot and preparation method thereof

Abstract

The invention relates to the technical field of photoelectric materials, in particular to a rare earth doped perovskite quantum dot and a preparation method thereof. The preparation method of the rare earth doped perovskite quantum dots comprises the following steps: mixing and dissolving a lead source, a rare earth source and a solvent to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen; reacting the mixed solution with excessive halogenated aliphatic amine precursors to obtain a reaction intermediate solution; the reaction intermediate solution reacts with a fatty acid cesium precursor, and the rare earth doped perovskite quantum dots are obtained after cooling. The preparation method of the rare earth doped perovskite quantum dots is good in controllability, low in requirements for reaction conditions and equipment and high in repetition rate, and the prepared rare earth doped perovskite quantum dots are good in luminescence performance and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and in particular to a rare earth doped perovskite quantum dot and a preparation method thereof. Background Art

[0002] All-inorganic lead halide perovskite is a luminescent material with excellent luminescent properties, with the advantages of narrow luminescent bandwidth, large absorption cross section and high luminescent efficiency. In order to further regulate and improve the luminescent properties of all-inorganic lead halide perovskite nanocrystals, rare earths can be doped into perovskites, such as terbium (Tb), europium (Eu), cerium (Ce), lanthanum (La) and ytterbium (Yb).

[0003] At present, there are two methods for synthesizing rare earth-doped perovskite quantum dots by solution method: Method 1: Using lead halide and rare earth halide salt as precursors, hot injection of cesium oleate at high temperature. The characteristic of this method is that lead halide and rare earth halide provide lead, rare earth and halogen at the same time; its disadvantage is that lead halide and rare earth halide salt have low solubility in the reaction system of octadecene, oleic acid and oleylamine, and it is easy to precipitate lead halide and rare earth halide salt at high temperature. This part of the precipitate cannot react with the injected cesium oleate, resulting in the product easily containing halide impurities, low quantum dot yield, low rare earth doping amount, poor quantum dot luminescence performance and poor synthesis repeatability. Method 2: Using cesium acetate, lead acetate and rare earth acetate as precursors, hot injection of trimethylchlorosilane at high temperature. The characteristic of this method is that lead, rare earth and cesium are used as precursors to separate the halogen independently. Because lead acetate and rare earth acetate have high solubility in octadecene, oleic acid, and oleylamine systems, this method is not prone to turbidity of the reactants; however, trimethylchlorosilane has a very low boiling point and is easily volatilized during hot injection, resulting in the loss of the halogen source, causing the lead halide perovskite to be rich in halogen vacancy defects, reducing the luminescence performance and stability. In addition, trimethylchlorosilane, as a halogen source, usually provides halogens in the form of hydrogen halides, and the halogens provided lack the complex protection of organic groups. Therefore, cesium, lead, and rare earth react with halogens at an extremely fast rate to form perovskite quantum dots. The controllability of the synthesis process is low, which easily leads to uneven perovskite size, large differences in luminescence performance between different batches of products, and low synthesis repeatability.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first purpose of the present invention is to provide a method for preparing rare earth-doped perovskite quantum dots, which completely or partially solves the problems existing in the prior art, such as low controllability of the synthesis process of rare earth-doped perovskite quantum dots, high requirements on reaction conditions, poor repeatability, and poor luminescence performance and stability of the prepared quantum dots.

[0006] The second object of the present invention is to provide a rare earth doped perovskite quantum dot having excellent luminescence performance and stability.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] The present invention provides a method for preparing rare earth-doped perovskite quantum dots, comprising the following steps:

[0009] Mixing and dissolving a lead source, a rare earth source and a solvent to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen;

[0010] reacting the mixed solution with an excess of a halogenated fatty amine precursor to obtain a reaction intermediate solution;

[0011] The reaction intermediate solution reacts with the fatty acid cesium precursor, and after cooling, the rare earth-doped perovskite quantum dots are obtained.

[0012] Furthermore, the rare earth elements in the rare earth source include any one or more of lanthanide metals.

[0013] Furthermore, the rare earth source includes at least one of an ytterbium source, a cerium source, a praseodymium source, a neodymium source, a europium source, a terbium source, a dysprosium source and an erbium source.

[0014] Furthermore, the molar ratio of the lead source to the rare earth source is 1:(0.2-5).

[0015] Further, it includes at least one of the following features (1) to (3);

[0016] (1) The volume ratio of the mixed solution to the halogenated fatty amine precursor is (5-20):1;

[0017] (2) The conditions for the reaction of the mixed solution with the halogenated fatty amine precursor are: reacting at 110 to 130° C. under vacuum conditions for 15 to 60 minutes;

[0018] (3) The halogenated fatty amine precursor is injected into the mixed solution at one time.

[0019] Furthermore, the molar ratio of the lead element in the mixture to the halogen element in the halogenated fatty amine precursor is 1:(4-12).

[0020] Furthermore, the method for preparing the halogenated fatty amine precursor comprises the following steps: a fatty amine and a hydrohalic acid react to obtain the halogenated fatty amine precursor.

[0021] Furthermore, the fatty amine includes an organic amine with a carbon atom length of C8 to C22.

[0022] Furthermore, the hydrohalic acid includes HCl and / or HBr.

[0023] Furthermore, the molar ratio of the fatty amine to the hydrohalic acid is (4-19):1.

[0024] Further, it includes at least one of the following features (1) to (3);

[0025] (1) The temperature of the reaction of the reaction intermediate solution and the fatty acid cesium precursor is 240 to 270° C.;

[0026] (2) The reaction time of the reaction intermediate solution and the fatty acid cesium precursor is 5 to 900 seconds;

[0027] (3) The cooling method includes at least one of air cooling, natural cooling and water cooling.

[0028] The present invention also provides a rare earth doped perovskite quantum dot, which is prepared by the method for preparing the rare earth doped perovskite quantum dot as described above.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The preparation method of rare earth-doped perovskite quantum dots of the present invention avoids the generation of insoluble raw materials and intermediate precipitates during the preparation process, ensures that the rare earth is uniformly incorporated into the perovskite lattice, improves the crystal quality, and thus improves the luminescence performance and stability of the rare earth-doped perovskite quantum dots.

[0031] 2. The preparation method of rare earth-doped perovskite quantum dots of the present invention improves the controllability of the synthesis process, eliminates the need to strictly control the reaction time and cooling rate, reduces the difficulty of synthesis, and reduces the requirements for reaction conditions and equipment.

[0032] 3. The preparation method of rare earth-doped perovskite quantum dots of the present invention improves the synthesis repetition rate, and the synthesized rare earth-doped lead halide perovskite has a high average luminescence efficiency, such as the average luminescence efficiency of ytterbium-doped lead halide perovskite is greater than 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a schematic diagram of the process flow of traditional method 1, traditional method 2 and the preparation method of the present invention.

[0035] Figure 2 The CsPbCl3:Yb quantum dots of Example 1 of the present invention and the CsPb(Cl 0.8 Br 0.2 )3: Yb quantum dots and CsPb(Cl 0.5 Br 0.5 )3: XRD pattern of Yb quantum dots.

[0036] Figure 3 The CsPbCl3:Yb quantum dots of Example 1 of the present invention and the CsPb(Cl 0.8 Br 0.2 )3: Yb quantum dots and CsPb(Cl 0.5 Br 0.5 )3: Fluorescence spectrum of Yb quantum dots under 365nm excitation light.

[0037] Figure 4 Box plots of the luminous efficiency of different batches of quantum dots prepared by the preparation methods of Example 1, Comparative Example 1, and Comparative Example 7, respectively, of the present invention.

[0038] Figure 5 This is a comparison chart of the luminous efficiency of quantum dots obtained by different preparation methods at 250° C. for different reaction times in the present invention.

[0039] Figure 6 This is a comparison chart of the luminous efficiency of quantum dots obtained by using different preparation methods of the present invention after reacting at a reaction temperature of 250° C. for 5 seconds and using different cooling methods.

[0040] Figure 7 This is a storage stability test chart of quantum dots prepared in Example 1, Comparative Example 1 and Comparative Example 7 of the present invention. DETAILED DESCRIPTION

[0041] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0042] The following is a detailed description of a rare earth-doped perovskite quantum dot and a preparation method thereof according to an embodiment of the present invention.

[0043] Octadecene, oleic acid and oleylamine are a common combination of quantum dot reaction solvents, which have the advantages of high boiling point, good solubility for non-polar raw materials, and moderate viscosity, but poor solubility for various inorganic salts. When inorganic salts are involved in the reaction raw materials or reaction intermediates, precipitation is easy to precipitate in the reaction system, resulting in an imbalance in the ratio of reactants actually involved in the reaction, resulting in impurities in the final product, low product performance, low yield, and even the failure to generate the expected product.

[0044] In the preparation process of rare earth-doped lead halide perovskite quantum dots, inorganic salt precipitates that are easily present include at least one of lead halide, rare earth halide and rare earth oxide.

[0045] Lead halide PbX2 (X = Cl, Br, I): Since the electronegativity of Pb is close to that of halogen, lead halide is a covalent compound. The solubility of lead halide in both polar and non-polar solvents is extremely low, and chemical reactions are usually required to effectively dissolve lead halide. For the preparation of lead halide perovskite, the generation of lead halide is inevitable, and there are usually three solutions: 1. Increase the ligand, that is, increase the amount of oleic acid and oleylamine, and react the lead halide into oil-soluble lead oleate and oleylamine halide through ion exchange reaction. However, the large amount of oleylamine introduced is harmful to the lead halide perovskite itself. Too much oleylamine will etch and dissolve the lead halide perovskite product itself, promoting the easy decomposition of the perovskite; 2. Use lead carboxylate as the lead source, and do not introduce halogens in the process of preparing the reaction precursor, but only inject trimethylhalosilane as the halogen source during the final hot injection. In this method, the lead source usually reacts with oleic acid and exists mainly in the form of lead oleate (PbOA). Since there is no halogen in the entire solution system before the final injection of the halogen source for reaction, no insoluble lead halide will be generated, and therefore, there is no need to add a large amount of oleic acid and oleylamine to assist in dissolution. After injecting the halogen source, lead, rare earth, halogen, and cesium will work together at high temperature to quickly form rare earth-doped lead halide perovskite. However, the boiling point of the halogen source trimethylhalosilane is very low, and it is very easy to volatilize and lose at a high temperature of >200°C, resulting in insufficient halogen in the reaction process, making the perovskite product rich in halogen vacancy defects, which in turn leads to low luminescence performance and poor stability of perovskite quantum dots; 3. Adding halogen, mainly through the chemical reaction PbX2+yRNH3X→[PbX (2+y) ](RNH3) y (y=1, 2, 3 or 4, X=Cl, Br), forming a soluble [PbX (2+y) ] y- ion clusters, but excessive halogen in the raw materials can easily lead to the formation of Cs4PbX6 impurity phase.

[0046] Rare earth halides: Rare earth halides are ionic compounds and cannot be well dissolved in low-polarity oil phase reaction systems. Therefore, it is usually necessary to appropriately increase the amount of oleic acid and oleylamine to assist dissolution.

[0047] Rare earth oxide: If oxygen-containing rare earth salts (such as ytterbium nitrate) are used and the amount of oleic acid in the reaction system is insufficient to form oleic acid rare earth, rare earth oxide precipitation will easily occur. The solubility of oleic acid and oleylamine ligands is not enough to dissolve rare earth oxide, so the appearance of rare earth oxide should be avoided during the reaction.

[0048] The synthesis of rare earth-doped perovskite quantum dots involves four raw materials: lead, rare earth, halogen and cesium. In order to prepare materials with good luminescent properties, it is necessary to ensure that the raw materials in the reaction solution will not form impurities and always exist in the form of a uniformly dispersed solution. Currently, the two traditional hot injection methods used are as follows:

[0049] Traditional method 1: The first step is to add lead, rare earth and halogen (lead halide and rare earth halide); the second step is hot injection to add cesium; this method has the following problems: lead halide and rare earth halide have poor solubility, and it is difficult to achieve the requirement of "uniform dispersion of raw materials".

[0050] Traditional method 2: The first step is to add lead and rare earth; add cesium; the second step is hot injection and adding halogen; this method has the following problems: the commonly used halogen source trimethylhalosilane evaporates too quickly, resulting in a lack of halogen in the synthesized perovskite; the reaction is violent when the halogen is injected, the synthesis process is difficult to control, and the perovskite formed has large particle size and many defects.

[0051] The present invention improves the reaction raw materials, synthesis process and reaction conditions in the preparation method of rare earth doped perovskite quantum dots, and solves the problems existing in the above-mentioned traditional preparation method of rare earth doped perovskite quantum dots.

[0052] In some embodiments of the present invention, a method for preparing rare earth-doped perovskite quantum dots is provided, comprising the following steps:

[0053] Mixing and dissolving a lead source, a rare earth source and a solvent to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen;

[0054] reacting the mixed solution with an excess of a halogenated fatty amine precursor to obtain a reaction intermediate solution;

[0055] The reaction intermediate solution reacts with a fatty acid cesium precursor, and rare earth-doped perovskite quantum dots are obtained after cooling.

[0056] The method for preparing rare earth doped perovskite quantum dots of the present invention comprises the following steps: firstly, lead and rare earth are added, then, halogenated fatty amine is added, and finally, cesium is added; raw materials of lead and rare earth are fed separately from halogen raw materials, thereby improving the solubility of the raw materials; halogenated fatty amine with better comprehensive performance is adopted to avoid volatilization of raw materials and generation of precipitation; and halogen source is added to form soluble lead rare earth halide ion groups which can be used as perovskite crystal nucleus seeds, thereby improving the controllability of the reaction and the uniformity of the product.

[0057] The present invention adjusts the reaction raw materials and the synthesis process to control the formed reaction intermediates, thereby forming reaction intermediates with better solubility and higher reaction activity, improving the controllability of the reaction, reducing the requirements for reaction conditions, avoiding the appearance of insoluble raw materials or intermediate precipitation, and achieving uniform nucleation of perovskite and uniform doping of rare earths, thereby improving the luminescence performance of perovskite quantum dots and the stability of quantum dots, and the synthesis repeatability is high.

[0058] The preparation method of rare earth doped perovskite quantum dots of the present invention solves the problems existing in the traditional preparation method of rare earth doped lead halide perovskite quantum dots, such as the presence of halide impurities in the quantum dots, low quantum dot yield, low rare earth doping amount, poor quantum dot luminescence performance, poor quantum dot stability, poor controllability of the preparation process, poor repeatability of the preparation method, and stringent requirements on conditions and equipment during the preparation process.

[0059] In some embodiments, the rare earth element in the rare earth source includes any one or more of the lanthanide metals.

[0060] In some embodiments, the rare earth source includes at least one of a ytterbium source, a cerium source, a praseodymium source, a neodymium source, a europium source, a terbium source, a dysprosium source, and an erbium source; preferably, the rare earth source includes a ytterbium source.

[0061] The preparation method of the present invention can be used to prepare the above-mentioned rare earth element-doped lead halide perovskite quantum dots. It is necessary to explain that since the ion radius of ytterbium is the smallest among all lanthanide rare earths and the difference with the lead ion radius is the largest, ytterbium is the most difficult to replace lead for doping among the lanthanide rare earths. The most prominent advantage of the present invention is that it has made a breakthrough in ytterbium doping.

[0062] In some embodiments, the rare earth-doped perovskite quantum dots include ytterbium-doped lead halide perovskite quantum dots.

[0063] Ytterbium-doped lead halide perovskites have unique quantum tailored luminescence properties, and their luminescence performance often exceeds 100%, so they have attracted widespread attention.

[0064] In ytterbium-doped lead halide perovskite, the energy difference between the excited state and the ground state of ytterbium is 1.3 eV, which is roughly half of the band gap of all-inorganic lead halide perovskite. When all-inorganic lead halide perovskite is excited, it can transfer energy with ytterbium, and excite two ground-state ytterbium ions to the excited state at one time, thus achieving the quantum tailoring effect of "paying one photon and getting two photons". 3+ ) and lead ions (Pb 2+ ) have different valence states and a large difference in ionic radius, so it is difficult to dope ytterbium into the perovskite lattice in the actual preparation process.

[0065] The traditional method for synthesizing ytterbium-doped lead halide perovskite quantum dots can synthesize perovskite quantum dots with quantum tailoring properties, but the controllability of the synthesis process is poor, and high requirements are placed on the control of experimental conditions and reaction vessels. The quality of the ytterbium-doped lead halide perovskite quantum dots obtained is not guaranteed, and the luminescence properties of different batches of products are prone to large fluctuations. The stability of the obtained quantum dots is poor and the synthesis repetition rate is low. The preparation method of the present invention overcomes the above problems and can produce ytterbium-doped lead halide perovskite quantum dots with excellent performance.

[0066] In some embodiments, the lead source and the rare earth source do not contain halogens, sulfur, phosphorus, silicon, arsenic, boron, and metal ions other than lead and rare earth.

[0067] In order to avoid precipitation of raw material solids during the reaction, the lead source and the rare earth source do not contain any ions or acid radicals that may lead to the production of sparingly soluble lead salts and sparingly soluble rare earth salts.

[0068] In some embodiments, the lead source includes lead oxide and lead oxyacid; preferably, the lead source includes at least one of lead oxide, lead carbonate, lead nitrate, lead acetate, lead oleate and lead stearate.

[0069] In some embodiments, the rare earth source includes oxygen-containing acid rare earth; preferably, the rare earth source includes at least one of rare earth carbonate, rare earth nitrate, rare earth acetate, rare earth oleate and rare earth stearate.

[0070] In some embodiments, the ytterbium source comprises an ytterbium oxyacid; preferably, the ytterbium source comprises at least one of ytterbium carbonate, ytterbium nitrate, ytterbium acetate, ytterbium oleate, and ytterbium stearate.

[0071] In some embodiments, the solvent includes fatty acids and octadecene.

[0072] In some embodiments, the fatty acid comprises an organic acid having a carbon atom length of C8 to C22; preferably, the fatty acid comprises at least one of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid and caprylic acid.

[0073] In some embodiments, the molar ratio of the lead source to the rare earth source is 1:(0.2-5); typically but not limiting, for example, the molar ratio of the lead source to the rare earth source can be 1:0.2, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or a range of any two thereof.

[0074] In some embodiments, the molar ratio of the lead source to the fatty acid is 1:(2-15); typically but not limiting, for example, the molar ratio of the lead source to the fatty acid can be 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:15 or a range of any two thereof.

[0075] In some embodiments, the volume ratio of fatty acid to octadecene is 1:(2-10); typically but not limiting, for example, the volume ratio of fatty acid to octadecene can be 1:2, 1:4, 1:6, 1:8, 1:10 or a range of any two thereof.

[0076] In some embodiments, the method for preparing a mixed solution comprises: mixing a lead source, a rare earth source, a fatty acid and octadecene, heating to 110-130° C., such as 120° C., under vacuum conditions, and reacting for 30-120 minutes to obtain a clear and transparent mixed solution.

[0077] The present invention mixes and dissolves a lead source, a rare earth source, a fatty acid and octadecene, and can disperse and mix lead ions and rare earth ions.

[0078] In some embodiments, the volume ratio of the mixed solution to the halogenated fatty amine precursor is (5-20):1; typically but not limiting, for example, the volume ratio of the mixed solution to the halogenated fatty amine precursor can be 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1 or a range of any two thereof.

[0079] In some embodiments, the molar ratio of the lead element in the mixed solution to the halogen element in the halogenated fatty amine precursor is 1:(4-12); typically but not limiting, for example, the molar ratio of the lead element in the mixed solution to the halogen element in the halogenated fatty amine can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12 or a range of any two thereof.

[0080] In some embodiments, the conditions for the reaction of the mixed solution with the halogenated fatty amine precursor are: reaction at 110-130°C and vacuum conditions for 15-60 minutes; typically but not limiting, for example, the reaction temperature can be 110°C, 115°C, 120°C, 125°C, 130°C or a range consisting of any two thereof; the reaction time can be 15min, 20min, 30min, 40min, 50min, 60min or a range consisting of any two thereof.

[0081] In some embodiments, the halogenated fatty amine precursor is injected into the mixed solution at one time.

[0082] The halogenated fatty amine precursor must be injected into the solution continuously and rapidly at one time, with the injection time not exceeding 5 seconds, and should not be added in batches or slowly dripped into the solution. In addition, the prepared reaction intermediate solution should be used up within 1 hour.

[0083] The present invention injects an excess of halogenated fatty amine precursor solution into a mixed solution containing lead and rare earth elements at one time to react and obtain a reaction intermediate; taking rare earth element ytterbium (Yb) as an example, the reaction intermediate is [Pb x Yb y X 6x+6y ] ion cluster. On the one hand, [Pb x Yb y X 6x+6y ] ion group can be dissolved in octadecene / fatty acid / fatty amine solvents, avoiding the formation of insoluble lead halide and ytterbium halide precipitation, which is beneficial to improve the reaction repeatability; on the other hand, [Pb x Yb y X 6x+6y ] Pb in ion clusters 2+ and Yb 3+ The perovskite formed by the reaction is not prone to halogen vacancy defects, which is beneficial to improve the stability of the product and reduce the control requirements for reaction time and temperature. It should be emphasized that the halogenated fatty amine should be added in a large excess, at least 4 times the amount of lead and ytterbium to ensure the formation of [Pb x Yb y X 6x+6y ]ion cluster.

[0084] In some embodiments, the method for preparing a halogenated fatty amine precursor comprises the following steps: a fatty amine and a hydrohalic acid react to obtain a halogenated fatty amine precursor.

[0085] In order to avoid halogen loss due to evaporation during the reaction, the present invention adopts halogenated fatty amine with a relatively high boiling point as the halogen source.

[0086] In some embodiments, the fatty amine includes an organic amine with a carbon atom length of C8 to C22; preferably, the fatty amine includes at least one of octylamine, decylamine, laurylamine, myristicamine, palmitylamine, oleylamine, stearylamine and oleylamine.

[0087] In some embodiments, the hydrohalic acid comprises HCl and / or HBr.

[0088] In some embodiments, the molar ratio of the fatty amine to the hydrohalic acid is (4-19):1; typically but not limiting, for example, the molar ratio of the fatty amine to the hydrohalic acid is 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 19:1 or a range of any two thereof.

[0089] In some embodiments, the preparation method of the halogenated fatty amine precursor comprises the following steps: after the fatty amine and the hydrohalic acid are mixed, they are heated to 110-130° C. under vacuum conditions, and the mixture is kept warm for 30-120 minutes to obtain the halogenated fatty amine precursor.

[0090] In some embodiments, the method for preparing a cesium fatty acid precursor comprises the following steps: reacting cesium carbonate, fatty acid and octadecene to obtain a cesium fatty acid precursor.

[0091] In some embodiments, in the method for preparing a cesium fatty acid precursor, the fatty acid includes an organic acid with a carbon atom length of C8 to C22; preferably, the fatty acid includes at least one of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid and caprylic acid.

[0092] In some embodiments, in the method for preparing a cesium fatty acid precursor, the molar ratio of cesium carbonate to fatty acid is 1:(3-5); typically but not limiting, for example, the molar ratio of cesium carbonate to fatty acid can be 1:3, 1:4, 1:5 or a range of any two thereof.

[0093] In some embodiments, in the method for preparing a fatty acid cesium precursor, the volume ratio of fatty acid to octadecene is 1:(5-20); typically but not limiting, for example, the volume ratio of fatty acid to octadecene can be 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20 or a range of any two thereof.

[0094] In some embodiments, the preparation method of the fatty acid cesium precursor comprises the following steps: cesium carbonate, fatty acid and octadecene are mixed, heated to 110-130° C. under vacuum conditions, and kept warm for 30-120 minutes to obtain the fatty acid cesium precursor.

[0095] In some embodiments, a fatty acid cesium precursor is injected into a reaction intermediate solution at 240 to 270° C. under an inert atmosphere, and rare earth-doped perovskite quantum dots are obtained after reaction and cooling.

[0096] In some embodiments, the volume ratio of the reaction intermediate solution to the fatty acid cesium precursor is 1:(5-40); typically but not limiting, for example, the volume ratio of the reaction intermediate solution to the fatty acid cesium precursor can be 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:40 or a range of any two thereof.

[0097] In some embodiments, the reaction temperature of the reaction intermediate solution and the fatty acid cesium precursor is 240-270°C; typically but not limiting, for example, the reaction temperature can be 240°C, 250°C, 260°C, 270°C or a range of any two thereof.

[0098] In some embodiments, the reaction time of the reaction intermediate solution and the fatty acid cesium precursor is 5 to 900 s; typically but not limiting, for example, the reaction time can be 5 s, 10 s, 50 s, 100 s, 150 s, 200 s, 300 s, 400 s, 500 s, 600 s, 700 s, 800 s, 900 s or a range of any two thereof.

[0099] In some embodiments, the cooling method includes at least one of air cooling, natural cooling and water cooling.

[0100] In the traditional solution hot injection process for synthesizing quantum dots, quantum dots tend to mature and grow at high temperatures, resulting in reduced performance. Therefore, a short reaction time (less than 5 seconds) and a fast cooling rate (usually an ice water bath is used to reduce the reaction solution temperature from 200°C to room temperature within 30 seconds) are required. This places high demands on condition control and reaction vessels, and also causes the reaction vessels to be easily damaged and scrapped under high temperature conditions.

[0101] In some specific embodiments, the method for preparing rare earth-doped perovskite quantum dots comprises the following steps:

[0102] Mixing and dissolving a lead source, a rare earth source, oleic acid and octadecene to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen;

[0103] reacting the mixed solution with an excess of halogenated oleylamine precursor to obtain a reaction intermediate solution;

[0104] The reaction intermediate solution reacts with a fatty acid cesium precursor to obtain a rare earth doped perovskite quantum dot precursor wrapped by oleic acid and / or oleylamine. The rare earth doped perovskite quantum dot precursor is cooled and washed to obtain a rare earth doped perovskite quantum dot.

[0105] In the above preparation method, octadecene is used as a solvent, which mainly plays a dilution and dispersion role; oleic acid and oleylamine are used as ligands, which, on the one hand, assist in dissolving other raw materials, and on the other hand, can be wrapped on the surface of the finally formed quantum dots to play a protective role.

[0106] See also Figure 1 , the traditional method 1 was used to prepare ytterbium-doped lead halide perovskite quantum dots, using lead halide and ytterbium halide as raw materials, and using oleic acid and oleylamine to dissolve. Oleic acid and oleylamine have relatively weak solubility. Although they can dissolve lead halide and ytterbium halide, on the one hand, they are easily dissociated at high temperatures, resulting in the re-precipitation of solid lead halide and ytterbium halide; on the other hand, oleic acid and oleylamine cannot completely disassemble the lattice of lead halide and ytterbium halide, resulting in ytterbium only being doped into the perovskite in the form of a "piece", which makes it easy for the perovskite to grow too large and affect the luminescence performance, and also makes it difficult for ytterbium to be doped into the perovskite lattice.

[0107] Ytterbium-doped lead halide perovskite quantum dots were prepared using the traditional method 2, with lead acetate, ytterbium acetate, and cesium acetate as raw materials, and oleic acid was used as a solubilizing agent. Trimethylhalosilane releases halogens very quickly, and at high temperatures, these halogens will nucleate with metal ions in an instant, resulting in many sites in the perovskite lattice that have not been fully occupied before crystals are formed. As a result, the perovskite formed has many defects, including many lead vacancies and halogen vacancies, resulting in poor stability of the perovskite and great uncontrollability of the synthesis.

[0108] The method for preparing ytterbium-doped lead halide perovskite quantum dots provided by the present invention comprises the following steps:

[0109] Mixing and dissolving a lead source, an ytterbium source and a solvent to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen;

[0110] reacting the mixed solution with a halogenated fatty amine precursor to obtain a reaction intermediate solution;

[0111] The reaction intermediate solution reacts with a fatty acid cesium precursor, and rare earth-doped perovskite quantum dots are obtained after cooling.

[0112] The present invention uses halogen-free lead oxyacid (or lead oxide) and rare earth oxyacid (taking ytterbium oxyacid as an example) as raw materials, so that all metal elements exist in a single ion and completely mixed form first; then, a sufficient halogen source (halogenated fatty amine) is added at one time, so that lead and ytterbium first form [PbX6] and [YbX6] metastable states soluble in oleic acid and oleylamine, as the lattice framework of the subsequent perovskite. In this step, the key lies in "one-time" and "sufficient" halogen. If the halogen is added in "multiple times" or "insufficient amount", then the precipitation of PbX2 and YbX3 will be formed preferentially. In addition, the halogen source uses a halogenated fatty amine with a moderate halogen release rate to improve the controllability of the reaction. The reaction time of this step should not be too short or too long to avoid insufficient reaction or precipitation of more stable PbX2 and YbX3 precipitation. Finally, the cesium source is injected. Since the lattice framework [PbX6] and [YbX6] that can be used as the subsequent perovskite have been formed, the number of nuclei formed during perovskite nucleation is large and the reaction uniformity is high, which makes the probability of ytterbium entering the perovskite lattice higher and the doping uniformity better. This also makes the formed perovskite have fewer defects, more resistant to high temperatures and long-term reactions, and the quantum dots can exist for a long time at high temperatures, and the formed perovskite product is also more stable.

[0113] The yield of the preparation method of the rare earth doped perovskite quantum dots of the present invention is ≤80%.

[0114] Since the synthesis of perovskite quantum dots involves ligands (i.e., the fatty amines and fatty acids used here will partially bind to the surface of the quantum dots for complexation and protection), the actual product contains many organic ligands in addition to the expected perovskite quantum dots, and the actual output is high, which in turn makes the yield high. According to calculations: the yield based on the mass of the product and all raw materials (including ligands and solvents) is up to about 7g / kg, or 5.5g / L; the yield based on the mass of the product and the mass of the reaction raw materials (excluding ligands and solvents) is up to about 500g / kg; the yield based on the ratio of actual output to theoretical output is up to about 80%.

[0115] In some embodiments of the present invention, a rare earth-doped perovskite quantum dot is also provided, which is prepared by the above-mentioned method for preparing the rare earth-doped perovskite quantum dot.

[0116] The rare earth-doped perovskite quantum dots prepared by the preparation method of the present invention have better stability, better defects and excellent luminescence performance.

[0117] In some embodiments, the content of the rare earth element in the rare earth-doped perovskite quantum dots is 0.001 wt % to 7 wt %. When the rare earth element is ytterbium, the doping amount of ytterbium can reach 7%.

[0118] In some embodiments, the size of the rare earth-doped perovskite quantum dots is 6 to 20 nm.

[0119] Example 1

[0120] The method for preparing CsPbCl3:Yb quantum dots provided in this embodiment comprises the following steps:

[0121] 0.15mmol lead acetate, 0.15mmol ytterbium acetate, 0.5mL oleic acid and 10mL octadecene were put into a three-necked flask, kept vacuumed, heated to 120℃ and kept warm for 60min to obtain an orange clear solution; then 0.75mL halogenated fatty amine precursor was added, and the temperature was maintained at 120℃ and vacuumed for 15min to obtain a clear lead ytterbium halide reaction intermediate solution; the temperature was then raised to 250℃, and 1mL fatty acid cesium precursor was immediately injected after reaching 250℃. After reacting for 30s, the reaction solution was air-cooled to room temperature (the cooling rate was about 50℃ / min) to obtain a reaction solution; the reaction solution was centrifuged, dispersed and washed with 10mL toluene, and centrifuged again to obtain a precipitate, which was dispersed in 10mL n-hexane to obtain CsPbCl3:Yb quantum dots.

[0122] The preparation method of the fatty acid cesium (cesium oleate) precursor comprises the following steps:

[0123] 0.8 g of cesium carbonate, 30 mL of octadecene and 3 mL of oleic acid were placed in a three-necked flask, vacuumed, heated to 120°C for 60 min, and a light yellow clear solution was obtained, which was the fatty acid cesium precursor. The obtained fatty acid cesium precursor was placed in a 120°C nitrogen environment for later use.

[0124] The preparation method of the halogenated fatty amine (oleylamine chloride) precursor comprises the following steps:

[0125] 20 mL of oleylamine and 1.7 mL of concentrated hydrochloric acid were placed in a three-necked flask, heated to 120° C. under vacuum conditions and kept warm for 30 min to obtain a halogenated fatty amine precursor.

[0126] Example 2

[0127] The CsPb(Cl 0.8 Br 0.2 )3: A method for preparing Yb quantum dots, comprising the following steps:

[0128] 0.15mmol lead oxide, 0.6mmol ytterbium acetate, 0.5mL oleic acid and 10mL octadecene were put into a three-necked flask, and the mixture was kept vacuumed and heated to 120℃ for 90min to obtain a brown-red clear solution; then 1.5mL halogenated fatty amine precursor was added, and the mixture was kept vacuumed at 130℃ for 15min to obtain a clear lead ytterbium halide reaction intermediate solution; the mixture was heated to 250℃, and 1mL fatty acid cesium precursor was immediately injected after reaching 250℃. After reacting for 5min, the mixture was cooled in a water bath to room temperature (the cooling rate was about 100℃ / min) to obtain a reaction solution; the reaction solution was centrifuged, dispersed and washed with 10mL toluene, and centrifuged again to obtain a precipitate, which was dispersed in 10mL n-hexane to obtain CsPb(Cl 0.8 Br 0.2 )3: Yb quantum dots.

[0129] The preparation method of the fatty acid cesium (cesium oleate) precursor is the same as that in Example 1.

[0130] The preparation method of the halogenated fatty amine (oleylamine chlorobromide) precursor is similar to that of Example 1, except that 1.7 mL of concentrated hydrochloric acid is replaced with 1.35 mL of concentrated hydrochloric acid and 0.5 mL of concentrated hydrobromic acid.

[0131] Example 3

[0132] The CsPb(Cl 0.5 Br 0.5 )3: A method for preparing Yb quantum dots, comprising the following steps:

[0133] 0.15mmol lead stearate, 0.1mmol ytterbium oleate, 0.5mL oleic acid and 10mL octadecene were put into a three-necked flask, vacuum was maintained, and the temperature was raised to 120℃ for 30min to obtain a light yellow clear solution; then 1mL halogenated fatty amine precursor was added, and the temperature was maintained at 120℃ for 15min to obtain a clear lead ytterbium halide reaction intermediate solution; the temperature was raised to 260℃, and 1mL fatty acid cesium precursor was immediately injected after reaching 260℃, and after reacting for 15min, the reaction solution was cooled to room temperature in a water bath (the cooling rate was about 100℃ / min) to obtain a reaction solution; the reaction solution was centrifuged, dispersed and washed with 10mL toluene, and centrifuged again to obtain a precipitate, which was dispersed in 10mL n-hexane to obtain CsPb(Cl 0.5 Br 0.5 )3: Yb quantum dots.

[0134] The preparation method of the fatty acid cesium (cesium octanoate) precursor is similar to that of Example 1, except that oleic acid is replaced by octanoic acid.

[0135] The preparation method of the halogenated fatty amine (octylamine chlorobromide) precursor is similar to that of Example 1, except that oleylamine is replaced by octylamine, and 1.7 mL of concentrated hydrochloric acid is replaced by 0.75 mL of concentrated hydrochloric acid and 1.3 mL of concentrated hydrobromic acid.

[0136] Example 4

[0137] The preparation method of CsPbCl3:Yb quantum dots provided in this embodiment refers to that in Example 1, the only difference is that the reaction time after the injection of the fatty acid cesium precursor is 5s.

[0138] Example 5

[0139] The preparation method of CsPbCl3:Yb quantum dots provided in this embodiment refers to that in Example 1, except that the reaction time after the injection of the fatty acid cesium precursor is 5 minutes.

[0140] Example 6

[0141] The preparation method of CsPbCl3:Yb quantum dots provided in this embodiment refers to that in Example 1, except that the reaction time after the injection of the fatty acid cesium precursor is 15 minutes.

[0142] Example 7

[0143] The preparation method of CsPbCl3:Yb quantum dots provided in this embodiment refers to Example 1, except that the water bath is cooled to room temperature at a cooling rate of about 100°C / min.

[0144] Example 8

[0145] The preparation method of CsPbCl3:Yb quantum dots provided in this embodiment refers to Example 1, except that it is naturally cooled to room temperature at a cooling rate of about 10°C / min.

[0146] Comparative Example 1

[0147] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example comprises the following steps:

[0148] 0.15mmol lead chloride, 0.15mmol ytterbium chloride, 1.5mL oleic acid, 1.5mL oleylamine and 10mL octadecene were put into a three-necked flask, kept vacuumed, heated to 120°C and kept warm for 60min to obtain a light yellow clear solution; then heated to 250°C, and immediately injected with 1mL fatty acid cesium precursor after reaching 250°C, reacted for 5s, and cooled to room temperature in an ice water bath (cooling rate was about 100°C / min); a reaction solution was obtained; the reaction solution was centrifuged, dispersed and washed with 10mL toluene, and centrifuged again to obtain a precipitate, which was dispersed in 10mL n-hexane to obtain CsPbCl3:Yb quantum dots.

[0149] The preparation method of the fatty acid cesium (cesium oleate) precursor is the same as that in Example 1.

[0150] Comparative Example 2

[0151] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 1, the only difference being that the reaction time after the injection of the fatty acid cesium precursor is 30 seconds.

[0152] Comparative Example 3

[0153] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 1, the only difference being that the reaction time after the injection of the fatty acid cesium precursor is 5 minutes.

[0154] Comparative Example 4

[0155] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 1, the only difference being that the reaction time after the injection of the fatty acid cesium precursor is 15 minutes.

[0156] Comparative Example 5

[0157] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 1, the only difference being that the method is air-cooled to room temperature at a cooling rate of about 50°C / min.

[0158] Comparative Example 6

[0159] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 1, except that it is naturally cooled to room temperature at a cooling rate of about 10°C / min.

[0160] Comparative Example 7

[0161] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example comprises the following steps:

[0162] 0.15mmol lead acetate, 0.15mmol ytterbium acetate, 1mL oleic acid, 0.5mL oleylamine and 10mL octadecene were put into a three-necked flask, kept vacuumed, heated to 120°C and kept warm for 60min to obtain a colorless clear solution; then heated to 250°C, and immediately injected with a mixed solution of 0.2mL trimethylsilyl chloride (TMSCl) and 0.5mL octadecene after reaching 250°C, reacted for 5s, and cooled to room temperature in an ice-water bath (cooling rate was about 100°C / min) to obtain a reaction solution; the reaction solution was centrifuged, dispersed and washed with 10mL toluene, and centrifuged again to obtain a precipitate, which was dispersed in 10mL n-hexane to obtain CsPbCl3:Yb quantum dots.

[0163] Comparative Example 8

[0164] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 7, the only difference being that the reaction time is 30s.

[0165] Comparative Example 9

[0166] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 7, the only difference being that the reaction time is 5 minutes.

[0167] Comparative Example 10

[0168] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 7, the only difference being that the reaction time is 15 minutes.

[0169] Comparative Example 11

[0170] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 7, the only difference being that the method is air-cooled to room temperature, and the cooling rate is about 50°C / min.

[0171] Comparative Example 12

[0172] The preparation method of CsPbCl3:Yb quantum dots provided in this comparative example refers to comparative example 7, the only difference being that it is naturally cooled to room temperature, and the cooling rate is about 10°C / min.

[0173] Test Example 1

[0174] The CsPbCl3:Yb quantum dots, CsPb(Cl 0.8 Br 0.2 )3: Yb quantum dots and CsPb(Cl 0.5 Br 0.5 )3: XRD test of Yb quantum dots, the results are as follows Figure 1 shown.

[0175] from Figure 1 It can be seen that the peak positions in the XRD characterization diagrams of the quantum dots prepared in Examples 1 to 3 of the present invention completely match the CsPbCl3 standard card (PDF#75-0411), indicating that ytterbium-doped cubic lead halide perovskite quantum dots were successfully synthesized.

[0176] Under 365 nm excitation light, the CsPbCl3:Yb quantum dots, CsPb(Cl 0.8 Br 0.2 )3: Yb quantum dots and CsPb(Cl 0.5 Br0.5 )3: Yb quantum dots were tested for fluorescence spectrum, and the results are as follows Figure 2 shown.

[0177] from Figure 2 It can be seen that there is an obvious ytterbium ion luminescence peak at 980nm, which further illustrates that ytterbium has been successfully incorporated into the lead halide perovskite lattice.

[0178] The preparation method of Example 1 (improved method), the preparation method of Comparative Example 1 (conventional method 1) and the preparation method of Comparative Example 7 (conventional method 2) were respectively used to repeatedly prepare quantum dots. The luminous efficiency (PLQY) of quantum dots prepared in different batches by each method is as follows: Figure 3 shown.

[0179] from Figure 3 It can be seen that the preparation methods of Comparative Example 1 and Comparative Example 7 have low repeatability. Although ytterbium-doped lead halide perovskite with PLQY>100% can also be prepared, the average PLQY is <50%. Different batches of ytterbium-doped lead halide perovskite prepared by the preparation method of the present invention have an average PLQY>110%, which greatly improves repeatability.

[0180] The luminous efficiency of the quantum dots prepared in Example 1, Example 4, Example 5, Example 6, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 7, Comparative Example 8, Comparative Example 9 and Comparative Example 10 was tested, and the results are as follows: Figure 4 shown. Figure 4 In the figure, the improved method represents the luminous efficiency of quantum dots obtained by the preparation method of Example 1 at different reaction times at 250°C; the traditional method one represents the luminous efficiency of quantum dots obtained by the preparation method of Comparative Example 1 at different reaction times at 250°C; the traditional method two represents the luminous efficiency of quantum dots obtained by the preparation method of Comparative Example 7 at different reaction times at 250°C.

[0181] from Figure 4 It can be seen that the ytterbium-doped lead halide perovskite prepared by the preparation method of the present invention has better lattice stability at high temperature, and can maintain PLQY>110% even at a reaction temperature of 250°C for 15 minutes. Figure 5 The reaction time also shows that the perovskite quantum dots can be stably obtained at a reaction time of 5s, 30s, 300s, 900s, or any time period between the two. This also shows that the preparation method of the present invention can reduce the strict requirements of the reaction time for the synthesis of perovskite quantum dots by hot injection of the solution, improve the controllability of the synthesis, and thus help improve the repeatability of the synthesis.

[0182] The luminous efficiency of the quantum dots prepared in Example 1, Example 7, Example 8, Comparative Example 1, Comparative Example 5, Comparative Example 6, Comparative Example 11 and Comparative Example 12 was tested, and the results are as follows: Figure 5 shown. Figure 5 In the figure, the improved method represents the luminous efficiency of quantum dots obtained by the preparation method of Example 1 without cooling; the traditional method one represents the luminous efficiency of quantum dots obtained by the preparation method of Comparative Example 1 without cooling; the traditional method two represents the luminous efficiency of quantum dots obtained by the preparation method of Comparative Example 7 without cooling.

[0183] from Figure 5 It can be seen that in the conventional method 1 and the conventional method 2, since the perovskite lattice is unstable at high temperature, ripening growth easily occurs, causing the perovskite to grow into a bulk material rather than a quantum dot, resulting in a decrease in luminescence performance. The preparation method of the present invention, since the ytterbium-doped lead halide perovskite obtained has better lattice stability, does not need to use a rapid cooling process such as water cooling to reduce the system temperature as quickly as possible to stabilize the quantum dots, thereby reducing the control requirements for the perovskite quantum dot synthesis process, thereby improving the controllability and repeatability of the synthesis. This also shows that the preparation method of the present invention does not require the use of a temperature-resistant reaction vessel, which is beneficial to extending the life of the reaction vessel and reducing the cost of the reaction equipment.

[0184] The stability of the quantum dots prepared in Example 1, Comparative Example 1 and Comparative Example 7 was tested, and the results are as follows: Figure 6 shown. Figure 6 In the embodiment, the improved method is Example 1, the traditional method one is Comparative Example 1, and the traditional method two is Comparative Example 7.

[0185] from Figure 6 It can be seen that the ytterbium-doped lead halide perovskite quantum dots prepared by the preparation method of the present invention have better stability, which means that they have fewer defects.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing rare earth-doped perovskite quantum dots, characterized in that: The steps include: Mixing and dissolving a lead source, a rare earth source and a solvent to obtain a mixed solution; wherein the lead source and the rare earth source do not contain halogen; reacting the mixed solution with an excess of a halogenated fatty amine precursor to obtain a reaction intermediate solution; The reaction intermediate solution reacts with the fatty acid cesium precursor, and after cooling, the rare earth-doped perovskite quantum dots are obtained.

2. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The rare earth elements in the rare earth source include any one or more of the lanthanide metals.

3. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The rare earth source includes at least one of a ytterbium source, a cerium source, a praseodymium source, a neodymium source, a europium source, a terbium source, a dysprosium source and an erbium source.

4. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The molar ratio of the lead source to the rare earth source is 1:(0.2-5).

5. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The method comprises at least one of the following features (1) to (3); (1) The volume ratio of the mixed solution to the halogenated fatty amine precursor is (5-20):1; (2) The conditions for the reaction of the mixed solution with the halogenated fatty amine precursor are: reacting at 110 to 130° C. under vacuum conditions for 15 to 60 minutes; (3) The halogenated fatty amine precursor is injected into the mixed solution at one time.

6. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The molar ratio of the lead element in the mixed solution to the halogen element in the halogenated fatty amine precursor is 1:(4-12).

7. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The method for preparing the halogenated fatty amine precursor comprises the following steps: a fatty amine and a hydrohalic acid react to obtain the halogenated fatty amine precursor.

8. The method for preparing rare earth-doped perovskite quantum dots according to claim 7, characterized in that: The fatty amines include organic amines with carbon atom lengths of C8 to C22; And / or, the hydrohalic acid comprises HCl and / or HBr; And / or, the molar ratio of the fatty amine to the hydrohalic acid is (4-19):

1.

9. The method for preparing rare earth-doped perovskite quantum dots according to claim 1, characterized in that: The method comprises at least one of the following features (1) to (3); (1) The temperature of the reaction of the reaction intermediate solution and the fatty acid cesium precursor is 240 to 270° C.; (2) The reaction time of the reaction intermediate solution and the fatty acid cesium precursor is 5 to 900 seconds; (3) The cooling method includes at least one of air cooling, natural cooling and water cooling.

10. A rare earth doped perovskite quantum dot, characterized in that: The rare earth-doped perovskite quantum dots are prepared by the preparation method according to any one of claims 1 to 9.

Images