CN114507519B

CN114507519B - Normal-temperature green synthesis method of deep blue perovskite quantum dots and application of deep blue perovskite quantum dots in preparation of perovskite light-emitting diode

Info

Publication number: CN114507519B
Application number: CN202210409019.6A
Authority: CN
Inventors: 陈淑芬; 陈焱峰; 马娟; 刘颖
Original assignee: Nanjing University of Posts and Telecommunications
Current assignee: Nanjing University of Posts and Telecommunications
Priority date: 2022-04-19
Filing date: 2022-04-19
Publication date: 2022-06-24
Anticipated expiration: 2042-04-19
Also published as: CN114507519A

Abstract

The invention discloses a normal-temperature green synthesis method of deep blue light perovskite quantum dots and application of the deep blue light perovskite quantum dots in preparation of perovskite light emitting diodes. The method comprises the following steps: 1) dissolving a compound containing A in a green solvent to obtain a precursor solution containing A for later use after the compound containing A is completely dissolved; 2) mixing a strong acid solvent and a compound containing B until the compound is completely dissolved to obtain a precursor solution containing B for later use; 3) sequentially adding the precursor solution containing A and the short-chain amine ligand prepared in the step 1) into an ester solvent, quickly injecting the precursor solution containing B prepared in the step 2), fully stirring for a period of time, and then terminating the reaction; and centrifuging and purifying to obtain the deep blue light perovskite quantum dot solution. The obtained perovskite quantum dot solution can be used for constructing a high-efficiency and stable deep blue light perovskite light emitting diode. The method has the advantages of small pollution of waste liquid, high perovskite quantum dot light emitting efficiency and the like.

Description

Normal-temperature green synthesis method of deep blue perovskite quantum dots and application of deep blue perovskite quantum dots in preparation of perovskite light-emitting diode

Technical Field

The invention relates to a synthesis method and application of deep blue light perovskite quantum dots, and mainly relates to a normal-temperature green synthesis method of deep blue light perovskite quantum dots and application of the deep blue light perovskite quantum dots in preparation of perovskite light emitting diodes.

Background

Metal halide perovskites have become a very promising material for next generation photovoltaic applications due to their excellent luminescent properties, simple synthesis, high luminescent quantum yield and low defect tolerance. The classic synthesis method of the perovskite quantum dots reported at present mainly comprises the following steps: a. high temperature thermal injection method, b, ligand assisted reprecipitation method, c, micro emulsion method, d, mechanical grinding method, etc. Generally, the high-temperature thermal injection method uses toxic solvents and dispersants, and requires high temperature and inert gas shielding; ligand assisted reprecipitation method and microemulsionAll liquid methods will adoptN,N-toxic solvents such as dimethylformamide, dimethylsulfoxide, toluene, chlorobenzene, etc. These toxic solvents can cause serious environmental pollution, which is contrary to the concept of sustainable development. And the mechanical grinding method is difficult to form a film due to the solubility problem, and cannot meet the commercial development requirement. In addition, most of the high-performance blue-light perovskite light-emitting diodes at the present stage are concentrated in the sky blue light range, the development of pure blue light and deep blue light required by the display field is relatively slow, and the application of the perovskite light-emitting diodes in the high-end display field is severely restricted by the factors. The green synthesis method is particularly important for synthesizing the deep blue light perovskite quantum dots and preparing the corresponding light emitting diode.

Chinese patent CN112125332A discloses a full-bromo perovskite blue light quantum dot based on recrystallization and a preparation method thereof. Cesium bromide and lead bromide are used as raw materials, oleic acid and oleylamine are used as ligands,N,N-dimethylformamide is used as a solvent, and CsPbBr is prepared based on a recrystallization method₃Blue light perovskite quantum dots. The solvent and the dispersant used in the synthesis process are toxic solvents, which can cause serious damage to the environment; the ligands adopted for synthesis are long-chain ligands, so that the charge transmission performance is influenced; the perovskite quantum dot film prepared by the method has poor crystallinity, and is based on CsPbBr₃The blue light perovskite quantum dot film is not used for preparing the light-emitting diode.

Disclosure of Invention

The invention mainly aims to provide a normal-temperature green synthesis method of deep blue light perovskite quantum dots, which reduces the toxicity of a solvent in a synthetic product and the pollution of the solvent to the environment and is used for preparing perovskite light emitting diodes.

The invention aims to provide a normal-temperature green synthesis method of a deep blue perovskite quantum dot. The green synthesis method of the invention is a green synthesis method, which means that all solvents used in the invention are safe and environment-friendly solvents.

The second purpose of the invention is to provide the application of the deep blue light perovskite quantum dot prepared by the green synthesis method in the preparation of perovskite light emitting diodes.

The technical scheme of the invention is as follows:

the invention discloses a normal-temperature green synthesis method of deep blue light perovskite quantum dots, which comprises the following steps of:

1) dissolving a compound containing A in a solvent to obtain a precursor solution containing A for later use after the compound containing A is completely dissolved;

2) mixing a strong acid solvent and a compound containing B until the compound is completely dissolved to obtain a precursor solution containing B for later use;

3) sequentially adding the precursor solution containing A and the short-chain amine ligand prepared in the step 1) into an ester solvent, quickly injecting the precursor solution containing B prepared in the step 2), fully stirring for a period of time, and then terminating the reaction;

4) centrifuging the mother liquor after the reaction is stopped at a low rotating speed, and removing the precipitate to obtain a supernatant;

5) centrifuging the supernatant at a high rotating speed, reserving the centrifuged precipitate, and dispersing the precipitate into an ester solvent to obtain a centrifugally purified deep blue light perovskite quantum dot solution;

wherein the content of the first and second substances,

the steps 1) to 5) are carried out at room temperature and in an air environment. Preferably at room temperature 25 deg.c.

The compound containing A is one or more of cesium carbonate, cesium bromide, cesium acetate or cesium chloride; the precursor containing A is a precursor containing Cs; the precursor is a solution containing a certain raw material.

The compound containing B is one or more of lead bromide, lead acetate or lead chloride; the precursor containing B is a precursor containing Pb.

Further, in the step 1), the solvent is one or more of water, ethanol, butanol and acetic acid;

further, in the step 2), the strongly acidic solvent is one or more of hydrochloric acid, hydrobromic acid, caproic acid and caprylic acid;

further, in the step 3), the ester solvent is one or more of methyl acetate, ethyl benzoate or methyl benzoate; the short-chain amine ligand is one or more of butylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, tert-butylamine, n-butylamine, aniline or naphthylamine; the stirring time is 1-5 min.

Further, in the step 1), the compound containing A is cesium carbonate, and Cs is contained in the precursor solution containing Cs⁺The concentration was 3.6M. In the step 2), the compound containing B is lead bromide, and Pb is contained in a precursor solution containing Pb²⁺The concentration was 0.5M. In the step 3), the volume ratio of the Cs-containing precursor solution to the Pb-containing precursor solution to the short-chain amine ligand is 1: 20: 2-4.

When multiple amine ligands exist in the step 3), the volume ratio of the short-chain amine ligands can be any proportion, and the same volume can also be used.

Further, in the step 4), the centrifugation time is 3-5 min, and the centrifugation rotation speed is 8000 rpm and 5000-. More preferably at 5000 rpm for 5 min.

Further, in the step 5), the centrifugation time is 10-15 min, and the centrifugation rotation speed is 12000-15000 rpm; more preferably at 15000 rpm for 10 min. The ester solvent used is the same as that used in step 3), and the volume ratio of the ester solvent used in step 5) to that used in step 3) is 5: 1.

The invention also provides application of the deep blue light perovskite quantum dot prepared by the normal-temperature green synthesis method in preparation of a perovskite light emitting diode. The preparation of the perovskite light-emitting diode comprises the following steps: and spin-coating the deep blue light perovskite quantum dot solution on the hole transport layer.

Furthermore, the prepared perovskite light-emitting diode sequentially comprises an ITO electrode, a hole transport layer, a perovskite quantum dot thin film, an electron transport layer, an electron injection layer and a metal cathode.

Further, the ITO electrode is cleaned by acetone, ethanol and deionized water, and is dried, blown dry by nitrogen flow and treated by ultraviolet ozone.

Further, the hole transport layer material is polyethylenedioxythiophene: poly (styrene sulfonate) (PEDOT: PSS).

Further, the hole transport layer is prepared by spin coating on an ITO electrode and is subjected to annealing treatment at 120 ℃, and the thickness of the hole transport layer is 30 nm.

Further, when the deep blue light perovskite quantum dot solution is spin-coated on the hole transport layer, the spin-coating times are 8-15, the time of each spin-coating is 30 s, the rotation speed of each spin-coating is 1000 rpm,

further, the thickness of the perovskite quantum dot thin film light-emitting layer is 20 nm.

Further, the electron transport layer is 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), and the thickness of the electron transport layer is 40 nm. The electron injection layer is lithium fluoride (LiF), and the metal cathode is aluminum (Al). The thickness of LiF was 1 nm and the thickness of Al was 100 nm.

Furthermore, the electron transport layer, the electron injection layer and the metal cathode are all prepared by vacuum evaporation.

The invention adopts the following principle: the deep blue light perovskite quantum dot is synthesized by adopting a green synthesis method at normal temperature, and the crystallization and growth of the perovskite are mainly controlled by utilizing the polarity difference or solubility difference between an environment-friendly solvent and an anti-solvent. The environment-friendly solvent generally comprises water, alcohol, ester, alkane and other solvents, and can well dissolve the lead halide salt and the cesium salt. The method for synthesizing the deep blue light perovskite quantum dots at normal temperature mainly adopts a ligand-assisted reprecipitation method, takes short-chain amine as a ligand, an acid aqueous solution as an anti-solvent and esters as a solvent, induces the perovskite quantum dots to crystallize and separate out through polarity difference, and takes short-chain acid and amine as ligands to anchor on the surface of the perovskite quantum dots, thereby further preventing the quantum dots from growing and simultaneously improving the stability and the optical performance of the perovskite. Further purifying, and preparing corresponding light emitting diode.

Compared with the prior art, the invention has the following remarkable advantages:

1) the invention adopts the environment-friendly solvent and the anti-solvent to synthesize the perovskite quantum dot solution, thereby reducing the pollution of the toxic solvent to the environment. And can be stably synthesized at normal temperature, and has the advantages of low energy consumption, low raw material cost, short synthesis period and the like. Compared with the quantum dots synthesized by the traditional method, the obtained full-color display color gamut is wide, the solution stability is good, meanwhile, the short-chain ligand is beneficial to the transmission of carriers, and the efficiency of the perovskite light-emitting diode is improved.

2) The invention synthesizes the deep blue light CsPbBr by using an environment-friendly solvent as a solvent of a precursor, an acid aqueous solution as an anti-solvent, a short-chain amine ligand as a ligand pair and a ligand-assisted reprecipitation method₃Perovskite quantum dots. And excess amine ligand is removed by further centrifugal purification process, which is dispersed into ethyl acetate solvent. Meanwhile, the film based on the perovskite quantum dots can be used for constructing a deep blue perovskite light emitting diode, and the thickness of the film layer is further optimized, so that the deep blue perovskite light emitting diode (Pelens) with the maximum External Quantum Efficiency (EQE) of 1.71% is obtained.

3) The present invention has solved the technical problems of the prior art. As can be seen from fig. 6, the diffraction peak intensity of the XRD (200) crystal plane is much larger than that of the prior patent CN112125332A, which proves that the crystallinity is better. In addition, as can be seen from the voltage-current density graph in fig. 8, the current density of the thin film at 10 volts can reach 286.6 milliamperes per square centimeter, which proves that the charge transport performance of the thin film is better.

Drawings

FIG. 1 is a schematic diagram of the synthesis of perovskite quantum dots of the present invention;

FIG. 2 is a plot of fluorescence quantum yield (PLQY) over time for perovskite quantum dots prepared in example 1 of the present invention;

FIG. 3 is a transmission electron micrograph of perovskite quantum dots prepared according to example 1 of the present invention;

FIG. 4 is a Photoluminescence (PL) spectrum of perovskite quantum dots prepared in comparative example 1 and example 1;

FIG. 5 is an ultraviolet-visible absorption (UV-Vis) spectrum of perovskite quantum dots prepared in comparative example 1 and example 1;

FIG. 6 is a Photoluminescence (PL) spectrum of perovskite quantum dots prepared in comparative example 2;

FIG. 7 is an ultraviolet-visible absorption (UV-Vis) spectrum of the perovskite quantum dot prepared in comparative example 2;

FIG. 8 is an X-ray diffraction (XRD) pattern of the perovskite quantum dot prepared in example 1;

FIG. 9 is a schematic device structure of a perovskite light emitting diode prepared in example 2;

FIG. 10 is a graph of the voltage-current density-luminance characteristics of the perovskite light emitting diode prepared in example 2;

FIG. 11 is an Electroluminescence (EL) spectrum of a perovskite light emitting diode prepared in example 2;

fig. 12 is an External Quantum Efficiency (EQE) plot for the perovskite light emitting diode prepared in example 2.

Detailed Description

Objects, advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments. These embodiments are merely exemplary of the technical solutions of the present invention, and any technical solution formed by replacing or converting the equivalent thereof falls within the scope of the present invention. The technical solution of the present invention is further illustrated by the following examples.

The sources of materials involved in the present invention are illustrated below:

ethyl acetate (99.5%), glacial acetic acid (99.5%), hydrobromic acid (40 wt%) cesium carbonate (99.9%), octylamine (99.0%) and lead bromide (99.9%) in the present invention were all purchased from alatin, and tert-butylamine from carbofuran (99.5% purity). Polyethylene dioxythiophene: poly (styrene sulfonate) (PEDOT: PSS) (AI 4083) was purchased from Heraeus Materials and aluminum (Al, 99.99%) was purchased from Nichem Fine. 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi, 99.0%) and lithium fluoride (LiF, 99.0%) were purchased from the bamboo chemical industry. The above drugs were all used directly and were not further purified.

Comparative example 1

Under the room-temperature air environment, the ligand-assisted method is adopted to prepare the deep blue perovskite quantum dots, and the specific synthetic process is as follows:

(1) cs-containing precursor: 0.0586 g cesium carbonate and 100. mu.L glacial acetic acid were mixed and dissolved, placed in a 5 mL sample vial, and sonicated until the solids were well dissolved.

(2) Precursor containing Pb: 0.1835 g of lead bromide was mixed with 1 mL of aqueous hydrobromic acid, placed in a 5 mL sample vial and sonicated until the solid was completely dissolved.

(3) And (3) dripping 5 mu L of the Cs precursor into 10 mL of ethyl acetate, sequentially adding 5 mu L of octylamine and 5 mu L of tert-butylamine ligand at the stirring speed of 720 rpm, stirring the solution until the solution is clear and transparent, quickly injecting 100 mu L of the Pb-containing precursor solution, stirring for 1 minute, and then stopping the reaction.

(4) The resultant solution was centrifuged at 5000 rpm for 5 min, and the supernatant was retained.

(5) Centrifuging the supernatant at 8000 rpm for 10 min, removing the supernatant, adding ester solvent into the precipitate, wherein the ester solvent is the same as that in the step 3) and the volume ratio is 5: 1; and (4) uniformly dispersing by ultrasonic to obtain green synthesized perovskite quantum dots.

The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the quantum dot solution prepared in comparative example 1 are shown as 1 in fig. 4 and 1 in fig. 5, respectively.

Comparative example 2

comparative example 2 differs from comparative example 1 in that: in step (5), 2 centrifugal purification processes were performed, and other steps and technical parameters were the same as in comparative example 1.

The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the deep blue perovskite quantum dot solution prepared in comparative example 2 are shown in fig. 6 and fig. 7, respectively.

Example 1 perovskite quantum dots prepared by the method of the present invention

Under the room temperature air environment, a ligand-assisted method is adopted to synthesize the deep blue light perovskite quantum dots, and a schematic diagram of the synthesis process of the perovskite quantum dots of the embodiment is shown in fig. 1.

The specific synthetic process is as follows:

(5) Centrifuging the supernatant at 15000 rpm for 10 min, removing the supernatant, adding an ester solvent into the precipitate, wherein the ester solvent is the same as that in the step 3) and the volume ratio is 5: 1; and (4) uniformly dispersing by ultrasonic to obtain green synthesized perovskite quantum dots.

The difference between example 1 and comparative example 1 is: the supernatant in step (5) of example 1 was centrifuged at 15000 rpm for 10 min, and the other steps and technical parameters were the same as those in comparative example 1.

The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the deep blue perovskite quantum dot solution prepared in example 1 are shown in 2 in fig. 4 and 2 in fig. 5, respectively. The fluorescence quantum yield as a function of time, transmission electron microscopy pattern and X-ray diffraction pattern are shown in FIG. 2, FIG. 3 and FIG. 8, respectively.

Fig. 2 is a plot of PLQY versus time for the titanium ore quantum dots synthesized in example 1. As can be seen from fig. 2: the quantum dot solution synthesized in example 1 has better stability, and the PLQY can be increased to 48.47% after one week, which is caused by Ostwald ripening phenomenon. After two weeks, the PLQY decreased due to the aggregation of the quantum dots.

Fig. 3 is a transmission electron microscope image of the perovskite quantum dot prepared in example 1. As can be seen from fig. 3: the perovskite quantum dot synthesized in the invention embodiment 1 has an average size of 4.97 nm, is close to the exciton Bohr radius (5 nm) of a bulk material, and shows a strong quantum confinement effect.

Fig. 4 is a Photoluminescence (PL) spectrum of the perovskite quantum dots synthesized in comparative example 1 and example 1. As can be seen from 1 in fig. 4: the perovskite quantum dot synthesized in comparative example 1 has an excessive emission peak at 500 nm, which indicates that excessive perovskite nanocrystals in the quantum dot solution are not removed. And as can be seen in fig. 4 at 2: the PL peak position of the synthesized perovskite quantum dot in example 1 is only 454 nm, which shows deep blue light emission, no residue of perovskite nanocrystals, and narrow half-peak width (23 nm).

Fig. 5 is an ultraviolet-visible absorption (UV-Vis) spectrum of the perovskite quantum dots synthesized in comparative example 1 and example 1. As can be seen from 1 in fig. 5: the quantum dots synthesized in comparative example 1 have lower absorption strength, reflecting that the concentration is lower; and the exciton absorption peak is wider, which indicates that phase components are impure and perovskite nanocrystalline which is not removed by centrifugation exists. And as can be seen from 2 in fig. 5: the quantum dots synthesized in example 1 have a high absorption strength, reflecting a high concentration thereof, which is not favorable for the preparation of the perovskite light emitting layer. Meanwhile, the exciton absorption peak is relatively narrow, and a single quantum dot component is presented.

Fig. 6 is a Photoluminescence (PL) spectrum of the perovskite quantum dot synthesized in comparative example 2. As can be seen in fig. 6: the quantum dot synthesized in the comparative example 2 has a step at 508 nm, which shows that the perovskite quantum dot after twice centrifugal purification is damaged and has low stability.

Fig. 7 is an ultraviolet-visible absorption (UV-Vis) spectrum of the synthesized perovskite quantum dot of comparative example 2. As can be seen in fig. 7: the quantum dots synthesized in comparative example 2 have low absorption intensity and are only purified by half once, which shows that after 2 times of centrifugal purification, the concentration of the quantum dots is sharply reduced, and large-particle precipitates in the system are centrifuged out.

FIG. 8 shows X-ray diffraction (XRD) of perovskite quantum dots synthesized in example 1 of the present invention) Spectra. As can be seen from fig. 8: two characteristic peaks at 15.1 ° and 30.3 °, corresponding to CsPbBr, respectively₃The (100) and (200) crystal planes of (c). The perovskite quantum dot synthesized in the example 1 is cubic phase, has high purity and only has single CsPbBr₃Diffraction peaks of the phases.

Example 2

Perovskite light emitting diodes were prepared using the perovskite quantum dots prepared in example 1.

1) And ultrasonically cleaning the ITO anode by using acetone, ethanol and deionized water in sequence, blow-drying the surface by using nitrogen flow, and drying in an oven at 120 ℃. And after the ITO anode is cooled, carrying out ultraviolet ozone treatment for 20 min. Then, the mixture of PEDOT: and (3) coating the PSS solution on the surface of the ITO in a spinning way, and putting the ITO on a heating table at 120 ℃ for annealing for 20 min to obtain a hole transport layer with the thickness of 30 nm.

2) The ITO anode spin-coated with the hole transport layer was placed in a glove box filled with nitrogen, and the quantum dot solution was spin-coated on the surface of the hole transport layer at 1000 rpm for 10 times of 30 s per spin-coating, thereby preparing a light emitting layer having a thickness of 20 nm.

3) Putting the ITO glass coated with quantum dots in a vacuum evaporation device until the vacuum degree is 2 multiplied by 10^-4And when Pa is required, sequentially evaporating TPBi, LiF and Al on the surface of the material, wherein the thicknesses of the TPBi, the LiF and the Al are respectively 40 nm, 1 nm and 100 nm.

FIG. 9 is a schematic diagram of a device structure of a perovskite light emitting diode constructed in embodiment 2 of the invention, in which an anode is ITO conductive glass, a hole injection layer is poly (3, 4-ethylenedioxythiophene) -polystyrene sulfonic acid (PEDOT: PSS), and a blue-light perovskite layer is CsPbBr₃The electron transport layer is tri (1-phenyl-1H-benzimidazole-2-yl) benzene (TPBi), the electron injection layer is lithium fluoride (LiF), and the cathode is metal aluminum (Al).

FIG. 10 is a graph of the voltage-current density-luminance characteristics of a perovskite light emitting diode of the present invention. As can be seen from fig. 10: when the voltage is 10V, the current density reaches 286 mA/cm²Maximum luminance of 180 cd/m²Thus, the charge transport performance is better.

FIG. 11 is an Electroluminescence (EL) spectrum of a perovskite light emitting diode constructed in example 2 of the present invention. Where 1 is the spectrum at 4.0 volts, 2 is the spectrum at 4.5 volts, 3 is the spectrum at 5.0 volts, and 4 is the spectrum at 5.5 volts, as can be seen in FIG. 11: the electroluminescent peak position of the light-emitting diode is 454 nm, the deep blue light emission is shown, and the light-emitting peak position does not move along with the increase of voltage, which shows that the spectral stability is better.

Fig. 12 is a graph of the External Quantum Efficiency (EQE) of the perovskite light emitting diode constructed in example 2 of the present invention. It can be seen from FIG. 12 that the current density at which the current density is 2.78 mA/cm²The maximum external quantum efficiency of the deep blue light emitting device can reach 1.71%, and large efficiency roll-off does not exist.

The above description is only an example of the present invention and is not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention as described in the specification of the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.

Claims

1. A normal-temperature green synthesis method of deep blue perovskite quantum dots is characterized by comprising the following steps:

wherein, the steps 1) to 5) are carried out at room temperature and in an air environment;

the compound containing A is one or more of cesium carbonate, cesium bromide, cesium acetate or cesium chloride; the precursor containing A is a precursor containing Cs;

the compound containing B is one or more of lead bromide, lead acetate or lead chloride; the precursor containing B is a precursor containing Pb;

in the step 1), the solvent is one or more of water, ethanol, butanol and acetic acid;

in the step 2), the strong acid solvent is one or more of hydrochloric acid, hydrobromic acid, caproic acid and caprylic acid;

in the step 3), the ester solvent is one or more of methyl acetate, ethyl benzoate or methyl benzoate; the short-chain amine ligand is one or more of butylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, tert-butylamine, n-butylamine, aniline or naphthylamine; the stirring time is 1-5 min.

2. The room temperature green synthesis method of deep blue perovskite quantum dots according to claim 1,

in the step 1), the compound containing A is cesium carbonate; cs in precursor solution containing Cs⁺The concentration is 3.6M;

in the step 2), the compound containing B is lead bromide, and Pb is contained in a precursor solution containing Pb²⁺The concentration is 0.5M;

in the step 3), the volume ratio of the Cs-containing precursor solution to the Pb-containing precursor solution to the short-chain amine ligand is 1: 20: 2-4.

3. The normal-temperature green synthesis method of deep-blue perovskite quantum dots as claimed in claim 1, wherein in the step 4), the centrifugation time is 3-5 min, and the centrifugation rotation speed is 8000 rpm and 5000-.

4. The normal-temperature green synthesis method of deep blue perovskite quantum dots according to claim 1, wherein in the step 5), the centrifugation time is 10-15 min, and the centrifugation rotation speed is 12000-15000 rpm; the ester solvent used is the same as that used in step 3), and the volume ratio of the ester solvent used in step 5) to that used in step 3) is 5: 1.

5. Use of deep blue perovskite quantum dots prepared by the method according to any one of claims 1 to 4 in the preparation of perovskite light emitting diodes.

6. The use according to claim 5, wherein the perovskite light emitting diode comprises an ITO electrode, a hole transport layer, a thin film comprising deep blue perovskite quantum dots prepared according to the method of any one of claims 1 to 4, an electron transport layer, an electron injection layer and a metal cathode in this order.

7. Use according to claim 6, wherein the perovskite light emitting diode is prepared by the steps of: the deep blue light perovskite quantum dot prepared by the method according to any one of claims 1 to 4 is spin-coated on the hole transport layer, wherein the spin-coating times are 8-15, the time of each spin-coating is 30 s, and the rotation speed of each spin-coating is 1000 rpm.