A metal halide perovskite nanocrystal resistant to thermal-induced fluorescence quenching and preparation method and application thereof

Abstract

The application discloses a kind of metal halide perovskite nanocrystals resistant to heat-induced fluorescence quenching and preparation method and application thereof.The preparation method comprises the following steps: formamidine source, cesium source, guanidine source are dissolved in liquid organic acid, then mixed to obtain precursor solution A;Organic small molecule amine or organic small molecule amine acetate or organic small molecule amine carbonate is dissolved in liquid organic acid to obtain organic small molecule amine solution;Organic small molecule amine solution is mixed with precursor solution A to obtain precursor solution B;At room temperature, in air atmosphere, precursor solution B, lead precursor solution are mixed and stirred, then organic ammonium halide solution is added, continue to stir to obtain perovskite nanocrystal crude solution;Separation and purification are carried out to obtain perovskite nanocrystals.The application solves the problem of heat-induced fluorescence quenching of metal halide perovskite material, and at the same time ensures its charge transport performance, so that the material is suitable for preparing active layer of electroluminescent or photoluminescent LED.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of preparation of metal halide perovskite nanocrystals, in particular to a kind of metal halide perovskite nanocrystals resistant to heat-induced fluorescence quenching and its preparation method and application. BACKGROUND

[0002] No matter photoluminescence or electroluminescence device, it is impossible to completely avoid the generation of Joule heat in the working process, and heat-induced fluorescence quenching is a challenge that all luminescent materials need to face. Even the commercialized luminescent material K2SiF6:Mn 4+ , its photoluminescence (PL) intensity will decrease by about 25% after the temperature rises from 293 Kelvin (K) to 453 K. Similarly, traditional uncoated cadmium selenide (CdSe) quantum dots, after experiencing a heating process from 293 K to 400 K, the PL intensity loss is as high as 80%. Metal halide perovskite, as a new emerging semiconductor luminescent material, shows great application potential in the field of luminescent applications due to its spectral tunability, narrow emission line width, high fluorescence quantum yield and good solution processability. However, metal halide perovskite materials are also affected by heat-induced fluorescence quenching. For example, the PL heat loss of MAPbBr3 perovskite nanocrystals at high temperature of 400 K can reach 70%, and the PL intensity of CsPbBr3 perovskite nanocrystals decreases by more than 80% at 373 K.

[0003] There are mainly three strategies to suppress heat-induced fluorescence quenching of perovskite materials in the prior art: one is to integrate a refrigeration and heat dissipation device, which often needs to adjust the device architecture and has high cost. The other two are to keep the perovskite material away from the backlight source and to wrap a silica shell on the surface of the perovskite material. Unfortunately, these two strategies are usually only applicable to down-conversion light-emitting diodes (LEDs), but not to electroluminescent LEDs with perovskite materials as active layers. SUMMARY

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present application is to provide a preparation method of metal halide perovskite nanocrystals resistant to heat-induced fluorescence quenching. In the present application, by in-situ introducing the organic small molecule amine on the basis of the metal halide perovskite at room temperature and in air environment, the problem of heat-induced fluorescence quenching of metal halide perovskite materials is solved, and the charge transport performance of perovskite is maintained.

[0005] Another purpose of the present application is to provide metal halide perovskite nanocrystals resistant to heat-induced fluorescence quenching prepared by the above-mentioned preparation method.

[0006] Still another purpose of the present application is to provide the application of the above-mentioned metal halide perovskite nanocrystals resistant to heat-induced fluorescence quenching.

[0007] The object of the present application is achieved by the following technical solutions.

[0008] The present application provides a preparation method of metal halide perovskite nanocrystals resistant to thermal-induced fluorescence quenching, comprising the following steps:

[0009] Dissolve formamidine source, cesium source and guanidine source in liquid organic acid to obtain precursor solution A; the concentration of formamidine is 0.1-0.5 mmol / mL; the molar ratio of formamidine to cesium is 28:3-28:10; the molar ratio of formamidine to guanidine is 14:1-14:3.

[0010] Dissolve organic small molecule amine or acetate salt of organic small molecule amine or carbonate salt of organic small molecule amine in liquid organic acid to obtain organic small molecule amine solution; mix the organic small molecule amine solution with the precursor solution A to obtain precursor solution B; in the precursor solution B, the molar ratio of formamidine to organic small molecule amine is 14:1-14:7; the organic small molecule amine is phenethylamine, m-fluorophenethylamine, o-fluorophenethylamine, p-fluorophenethylamine, 4-(trifluoromethyl)phenethylamine or 4-(trifluoromethoxy)phenethylamine.

[0011] Mix and dissolve lead bromide and tetraoctylammonium bromide in toluene to obtain lead precursor solution.

[0012] Mix and stir the precursor solution B and the lead precursor solution under room temperature and air atmosphere, then add organic ammonium halide solution and continue stirring to obtain crude perovskite nanocrystal solution; separate and purify the crude perovskite nanocrystal solution to obtain perovskite nanocrystals.

[0013] Preferably, the formamidine source is formamidine acetate or formamidine carbonate; the cesium source is cesium carbonate or cesium acetate; and the guanidine source is guanidine carbonate or guanidine acetate.

[0014] Preferably, the liquid organic acid is at least one of oleic acid and octanoic acid.

[0015] Preferably, the organic ammonium halide solution is prepared by mixing and dissolving didodecyldimethylammonium bromide and oleylamine bromide in toluene to obtain the organic ammonium halide solution.

[0016] More preferably, in the organic ammonium halide solution, the concentration of didodecyldimethylammonium bromide is 0.008-0.02 mmol / mL, and the concentration of oleylamine bromide is 0.02-0.08 mmol / mL.

[0017] Preferably, in the lead precursor solution, the molar ratio of lead bromide to tetraoctylammonium bromide is 1:2-1:5.

[0018] Preferably, the molar ratio of formamidinium and cesium is (0.7-0.9):(0.1-0.3); more preferably, the molar ratio of formamidinium and cesium is 0.8:0.2.

[0019] The application also provides a metal halide perovskite nanocrystal resistant to thermally induced fluorescence quenching, which is prepared by the method for preparing the metal halide perovskite nanocrystal resistant to thermally induced fluorescence quenching.

[0020] Preferably, the metal halide peroviskite nanocrystal resistant to thermally induced fluorescence quenching has a structure of (FA / Cs)1PbBr3:GA / x-PEA, wherein FA is a monovalent formamidinium ion, Cs is a monovalent cesium ion, Pb is a divalent lead ion, Br is a monovalent bromine ion, GA is a guanidinium ligand, and x-PEA is the organic small molecule amine.

[0021] The application also provides an application of the metal halide peroviskite nanocrystal resistant to thermally induced fluorescence quenching, which is characterized by being used for preparing an active layer of an electroluminescent or photoluminescent LED.

[0022] Compared with the prior art, the application has the following advantages and beneficial effects:

[0023] (1) The method for preparing the metal halide peroviskite nanocrystal resistant to thermally induced fluorescence quenching increases the thermal activation energy and reduces the exciton-phonon coupling effect caused by lattice thermal vibration in the specific peroviskite system of the application by introducing a specific amount of a specific organic small molecule amine ligand, thereby enhancing the resistance to thermally induced fluorescence quenching and improving the thermal stability of the peroviskite nanocrystal.

[0024] (2) The metal halide peroviskite nanocrystal resistant to thermally induced fluorescence quenching can maintain 80-90% of the room temperature luminous intensity at a temperature of 380K, and the luminous intensity can be completely restored after experiencing a "heating-cooling" cycle, which shows great application prospects in the display and lighting fields, and is particularly suitable for preparing an electroluminescent or photoluminescent LED with a peroviskite material as an active layer.

[0025] (3) The preparation method of the anti-thermally induced fluorescence quenching metal halide perovskite nanocrystals of the present application does not use polar solvents, and high-quality and high-performance formamidinium metal halide perovskite nanocrystals are formed at room temperature; the organic small molecule amine ligand can control the crystallization rate of the perovskite in the synthesis process, thereby controlling the grain size and quality. Moreover, the organic small molecule amine ligand can also passivate the defects on the surface of the perovskite grain, reduce the surface lead dangling bond, make the exciton effectively radiative recombine in the core layer, and improve the radiative recombination luminescence efficiency. The prepared perovskite nanocrystals have a peak wavelength of 530 nanometers (nm) for luminescence, a half-peak width of only 21 nm, and a fluorescence quantum yield of 93%, which can meet the requirements of Rec.2020 standard for pure green light emission. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of Example 1 of the present application.

[0027] Figure 2 The excitation / photoluminescence spectrum of Example 1 of the present application.

[0028] Figure 3 The X-ray diffraction (XRD) spectrum of Example 1 of the present application.

[0029] Figure 4 The relative photoluminescence intensity change curve of Example 1 of the present application with temperature change in the 300K to 380K warming and 380K to 300K cooling cycle.

[0030] Figure 5 The relative photoluminescence intensity change curve of Example 1 of the present application with temperature change in the 300K to 380K warming and 380K to 300K cooling cycle.

[0031] Figure 6 The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of Example 2 of the present application.

[0032] Figure 7 The excitation / photoluminescence spectrum of Example 2 of the present application.

[0033] Figure 8 The X-ray diffraction (XRD) spectrum of Example 2 of the present application.

[0034] Figure 9 The relative photoluminescence intensity change curve of Example 2 of the present application with temperature change.

[0035] Figure 10 The relative photoluminescence intensity change curve of Example 2 of the present application with temperature change in the 300K to 380K warming and 380K to 300K cooling cycle.

[0036] Figure 11Photoluminescence spectrum and UV-Vis absorption spectrum of Comparative Example 1 of the present application.

[0037] Figure 12 Excitation / photoluminescence spectrum of Comparative Example 1 of the present application.

[0038] Figure 13 X-ray diffraction (XRD) pattern of Comparative Example 1 of the present application.

[0039] Figure 14 Temperature dependence of relative photoluminescence intensity of Comparative Example 1 of the present application.

[0040] Figure 15 Temperature dependence of relative photoluminescence intensity of Comparative Example 1 of the present application.

[0041] Figure 16 Photoluminescence spectrum and UV-Vis absorption spectrum of Comparative Example 2 of the present application.

[0042] Figure 17 Excitation / photoluminescence spectrum of Comparative Example 2 of the present application.

[0043] Figure 18 X-ray diffraction (XRD) pattern of Comparative Example 2 of the present application.

[0044] Figure 19 Temperature dependence of relative photoluminescence intensity of Comparative Example 2 of the present application.

[0045] Figure 20 Temperature dependence of relative photoluminescence intensity of Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0046] The present application will be further described in conjunction with the following examples, but the embodiments of the present application are not limited thereto.

[0047] Example 1

[0048] This example provides a phenethylamine (PEA)-modified formamidinium metal halide perovskite nanocrystal, the structure of which is (FA / Cs)1PbBr3: GA / PEA, and the specific synthesis process is as follows:

[0049] (1) Weigh 83.3 mg of formamidine acetate solid powder and add 4 mL of octanoic acid. Dissolve at 140 °C and cool to room temperature to prepare formamidine source; weigh 65.2 mg of cesium carbonate solid powder and add 2 mL of octanoic acid. Dissolve at 140 °C and cool to room temperature to prepare cesium source; weigh 24.2 mg of guanidine carbonate solid powder and add 2 mL of octanoic acid. Dissolve at 140 °C and cool to room temperature to prepare guanidine source; weigh 24.2 mg of liquid β-phenylethylamine and add 2 mL of octanoic acid. Dissolve at 140 °C and cool to room temperature to prepare amine source; then prepare precursor solution B according to the proportions in Table 1.

[0050] (2) Weigh 183.5 mg lead bromide and 546.8 mg tetra-n-octylammonium bromide solid powder and dissolve them in 10 mL toluene. After stirring thoroughly, a lead precursor solution is obtained.

[0051] (3) Weigh 80 mg of oleamine bromide and 40 mg of dodecyl dimethyl ammonium bromide solid powder and dissolve them in 10 mL of toluene. After stirring thoroughly, an organic ammonium halide solution is obtained.

[0052] (4) 280 μL of precursor solution B was injected into 2.5 mL of lead precursor solution under vigorous stirring. After stirring for 30 seconds, 830 μL of organic ammonium halide solution was added. After stirring for 2 min, a crude solution of perovskite nanocrystals was obtained.

[0053] (5) The product obtained in step (4) was mixed with methyl acetate (volume ratio 1:2) and centrifuged to purify it. The centrifugation speed was 11000 rpm and the time was 5 min to obtain the lower precipitate. The lower precipitate was redispersed in 1 mL of n-octane and centrifuged at 4000 rpm for 5 min to obtain the upper clear liquid.

[0054] (6) The supernatant obtained in step (5) is filtered with a polytetrafluoroethylene filter to obtain a purified metal halide perovskite nanocrystal colloidal solution.

[0055] The photoluminescence spectrum and ultraviolet-visible absorption spectrum of the perovskite nanocrystals prepared in this embodiment are as follows: Figure 1 As shown; the excitation / photoluminescence spectrum is as follows Figure 2 As shown, the perovskite nanocrystals exhibit a maximum fluorescence emission peak wavelength of 530 nm and a fluorescence quantum yield of 92%; X-ray diffraction is as follows... Figure 3 As shown.

[0056] Figure 4 and Figure 5The stability of the relative photoluminescence intensity with temperature change in the temperature increase and temperature increase-decrease cycles of the present embodiment is tested. It can be seen that at 380K, the luminescence intensity can still maintain 80% of that at 300K, and has good anti-thermal fluorescence quenching performance. After 2 cycles of temperature increase from 300K to 380K and temperature decrease from 380K to 300K, the luminescence intensity can still recover to 100% of the initial value, showing excellent thermal stability.

[0057] Table 1. Precursor solution B (unit: μL)

[0058]

[0059] Example 2

[0060] The present embodiment provides a melflumine (3-F-PEA) modified formamidinium metal halide perovskite nanocrystal, and the structure of the nanocrystal material is (FA / Cs)1PbBr3: GA / 3-F-PEA. The specific synthesis process is as follows:

[0061] (1) 83.3 milligrams (mg) of formamidinium acetate solid powder is weighed into 4 mL of octanoic acid, dissolved at 140 degrees Celsius (°C) and cooled to room temperature to prepare a formamidinium source; 65.2 mg of cesium carbonate solid powder is weighed into 2 mL of octanoic acid, dissolved at 140 °C and cooled to room temperature to prepare a cesium source; 24.2 mg of guanidine carbonate solid powder is weighed into 2 mL of octanoic acid, dissolved at 140 °C and cooled to room temperature to prepare a guanidine source; 27.8 mg of liquid melflumine is weighed into 2 mL of octanoic acid, dissolved at 140 °C and cooled to room temperature to prepare an amine source; and then precursor solution B is prepared according to the proportions in Table 2.

[0062] (2) 183.5 mg of lead bromide and 546.8 mg of tetra-n-octylammonium bromide solid powder are dissolved in 10 mL of toluene to obtain a lead precursor solution after sufficient stirring.

[0063] (3) 80 mg of oleylamine bromide and 40 mg of didodecyl dimethyl ammonium bromide solid powder are dissolved in 10 mL of toluene to obtain an organic halide solution after sufficient stirring.

[0064] (4) 280 μL of precursor solution B is injected into 2.5 mL of the vigorously stirred lead precursor solution, stirred for 30 seconds, then 830 μL of the mixed organic halide solution is added, and the stirring is continued for 2 min to obtain a perovskite nanocrystal crude solution.

[0065] (5) The product obtained in step (4) was mixed with methyl acetate (volume ratio 1:2) and purified by centrifugation at 11000 rpm for 5 min, and the precipitate was re-dispersed in 1 mL of n-octane and centrifuged at 4000 rpm for 5 min to obtain the supernatant.

[0066] (6) The supernatant obtained in step (5) was filtered with a polytetrafluoroethylene filter head to obtain a purified metal halide perovskite nanocrystal colloidal solution.

[0067] The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the perovskite nanocrystals prepared in this example are shown in FIGS. 1 and 2, respectively. Figure 6 The excitation / photoluminescence spectrum is shown in FIG. 3. Figure 7 The maximum fluorescence emission peak wavelength of the perovskite nanocrystals is 530 nm, and the fluorescence quantum yield is 93%. The X-ray diffraction is shown in FIG. 4. Figure 8

[0068] Figure 9 and Figure 10 are the stability tests of the relative photoluminescence intensity with respect to temperature in the temperature rising and temperature rising-falling cycles, respectively, of this example. It can be seen that at 380 K, the luminescence intensity can still maintain 90% of that at 300 K, showing good resistance to thermal fluorescence quenching. After 2 cycles of rising from 300 K to 380 K and falling from 380 K to 300 K, the luminescence intensity can still recover to 100% of the initial value, showing excellent thermal stability.

[0069] Table 2. Precursor solution B (unit: μL)

[0070]

[0071] Comparative Example 1

[0072] This comparative example provides a phenethylamine (PEA) modified cesium metal halide perovskite nanocrystal, and the structural composition of the nanocrystal material is (Cs / FA)1PbBr3: GA / PEA, and the specific synthesis process is as follows:

[0073] (1) 83.3 milligrams (mg) of formamidinium acetate solid powder was added to 4 mL of octanoic acid, dissolved at 140 degrees Celsius (℃), and cooled to room temperature to prepare a formamidinium source; 65.2 mg of cesium carbonate solid powder was added to 2 mL of octanoic acid, dissolved at 140 ℃, and cooled to room temperature to prepare a cesium source; 24.2 mg of guanidine carbonate solid powder was added to 2 mL of octanoic acid, dissolved at 140 ℃, and cooled to room temperature to prepare a guanidine source; 24.2 mg of liquid β-phenethylamine was added to 2 mL of octanoic acid, dissolved at 140 ℃, and cooled to room temperature to prepare an amine source; and then precursor solution C was prepared according to the proportions in Table 3. ​

[0074] (2) 183.5 mg of lead bromide and 546.8 mg of tetra-n-octylammonium bromide solid powder were weighed and dissolved in 10 mL of toluene to obtain a lead precursor solution.

[0075] (3) 80 mg of oleylamine bromide and 40 mg of didodecyldimethylammonium bromide solid powder were weighed and dissolved in 10 mL of toluene to obtain a mixed organic ammonium halide solution after sufficient stirring.

[0076] (4) 280 μL of the precursor solution B was injected into 2.5 mL of the lead precursor solution under vigorous stirring, and after stirring for 30 seconds, 830 μL of the mixed organic ammonium halide solution was added, and after continuing to stir for 2 min, a perovskite nanocrystal crude solution was obtained.

[0077] (5) The product obtained in step (4) was mixed with methyl acetate (volume ratio 1:2) and centrifuged, the centrifugal speed was 11000 rpm, and the time was 5 min, to obtain a lower layer precipitate, which was redispersed in 1 mL of n-octane and centrifuged, the centrifugal speed was 4000 rpm, and the time was 5 min, to obtain an upper layer clear solution.

[0078] (6) The upper layer clear solution obtained in step (5) was filtered with a polytetrafluoroethylene filter head to obtain a purified metal halide perovskite nanocrystal colloidal solution.

[0079] The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the perovskite nanocrystals prepared in the comparative example are shown in FIGS. 1 and 2, respectively; the excitation / photoluminescence spectrum is shown in FIG. 3, the maximum fluorescence emission peak wavelength of the perovskite nanocrystals is 518 nm, and the fluorescence quantum yield is 32%; the X-ray diffraction is shown in FIG. 4. Figure 11 Figure 12 Figure 13

[0080] Figure 14 and Figure 15 are the stability tests of the samples of the comparative example in the temperature rising and temperature rising-cooling cycles, respectively, the relative photoluminescence intensity changes with temperature. It can be seen that the luminescence intensity of sample 1 at 380K is 28% of that at 300K. Therefore, after experiencing 2 cycles of 300K to 380K and 380K to 300K, the luminescence intensity of sample 1 can recover to 89% of the initial value; the luminescence intensity of sample 2 at 380K is 37% of that at 300K. Therefore, after experiencing 2 cycles of 300K to 380K and 380K to 300K, the luminescence intensity of sample 2 can recover to 77% of the initial value.

[0081] From the above, it can be seen that in the preparation process of the cesium-based metal halide perovskite nanocrystals in the comparative example, the introduction of phenylethylamine cannot significantly improve the thermal stability. ​​​

[0082] Table 3. Precursor solution C (unit: μL)

[0083]

[0084] Comparative Example 2

[0085] This comparative example provides a formamidinium metal halide perovskite nanocrystal, the structure of which is (FA / Cs)1PbBr3: GA, and the specific synthesis process is as follows:

[0086] (1) 83.3 milligrams (mg) of formamidinium acetate solid powder was weighed into 4 mL of octanoic acid, dissolved at 140 degrees Celsius (°C) and cooled to room temperature to prepare a formamidinium source; 65.2 mg of cesium carbonate solid powder was weighed into 2 mL of octanoic acid, dissolved at 140 °C and cooled to room temperature to prepare a cesium source; 24.2 mg of guanidine carbonate solid powder was weighed into 2 mL of octanoic acid, dissolved at 140 °C and cooled to room temperature to prepare a guanidine source; and then precursor solution A was prepared according to the proportions in Table 4.

[0087] (2) 183.5 mg of lead bromide and 546.8 mg of tetra-n-octylammonium bromide solid powder were dissolved in 10 mL of toluene to obtain a lead precursor solution after sufficient stirring.

[0088] (3) 80 mg of oleylamine bromide and 40 mg of didodecyldimethylammonium bromide solid powder were dissolved in 10 mL of toluene to obtain a mixed organic ammonium halide solution after sufficient stirring.

[0089] (4) 280 μL of precursor solution A was injected into 2.5 mL of the lead precursor solution stirred vigorously, and after stirring for 30 seconds, 830 μL of the mixed organic ammonium halide solution was added, and after continuing to stir for 5 min, a crude perovskite nanocrystal solution was obtained.

[0090] (5) The product obtained in step (4) was mixed with methyl acetate (volume ratio 1:2) and centrifuged for purification, at a centrifugal speed of 11000 rpm for 5 min, to obtain a lower layer precipitate, which was redispersed in 1 mL of n-octane and centrifuged at a centrifugal speed of 4000 rpm for 5 min to obtain an upper layer clear solution.

[0091] (6) The upper layer clear solution obtained in step (5) was filtered with a polytetrafluoroethylene filter head to obtain a purified metal halide perovskite nanocrystal colloidal solution.

[0092] The photoluminescence spectrum and the ultraviolet-visible absorption spectrum of the perovskite nanocrystal prepared in this comparative example are shown in Figure 16 , the excitation / photoluminescence spectrum is shown in Figure 17 , the maximum fluorescence emission peak wavelength of the perovskite nanocrystal is 532 nm, and the fluorescence quantum yield is 83%. The X-ray diffraction is shown inFigure 18 Figure 2 shows the temperature dependence of the photoluminescence intensity of the sample of Example 1.

[0093] Figure 19 andFigure 4 shows the temperature dependence of the photoluminescence intensity of the sample of Example 2. Figure 20

[0094] Table 4. Formula of perovskite precursor solution A (unit: μL)

[0095]

[0096]

[0097] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods and shall be within the scope of the present application.

Claims

1. A method for preparing thermo-fluorescence-resistant perovskite nanocrystals of metal halide, characterized in that, Includes the following steps: The formamidine, cesium, and guanidine sources were dissolved in a liquid organic acid and then mixed to obtain precursor solution A; wherein the concentration of formamidine was 0.1~0.5 mmol / mL; the molar ratio of formamidine to cesium was 28:3~28:10; and the molar ratio of formamidine to guanidine was 14:1~14:

3. The formamidine source is formamidine acetate or formamidine carbonate; the cesium source is cesium carbonate or cesium acetate; the guanidine source is guanidine carbonate or guanidine acetate. An organic small molecule amine, its acetate, or its carbonate is dissolved in a liquid organic acid to obtain an organic small molecule amine solution; the organic small molecule amine solution is mixed with the precursor solution A to obtain a precursor solution B; in the precursor solution B, the molar ratio of formamidin to the organic small molecule amine is 14:1 to 14:7; the organic small molecule amine is phenylethylamine, m-fluorophenylethylamine, o-fluorophenylethylamine, p-fluorophenylethylamine, 4-(trifluoromethyl)phenylethylamine, or 4-(trifluoromethoxy)phenylethylamine; Lead bromide and tetraoctylammonium bromide were mixed and dissolved in toluene to obtain a lead precursor solution; Under room temperature and air atmosphere conditions, precursor solution B and lead precursor solution are mixed and stirred, then organic ammonium halide solution is added and stirring is continued to obtain a crude solution of perovskite nanocrystals. The perovskite nanocrystals were obtained through separation and purification.

2. The method for preparing thermo-fluorescence-resistant perovskite nanocrystals of metal halide according to claim 1, characterized in that, The liquid organic acid is at least one of oleic acid and octanoic acid.

3. The method for preparing thermo-fluorescence-resistant perovskite nanocrystals of metal halide according to claim 1, characterized in that, The organoammonium halide solution is prepared by dissolving bis(dodecyl)dimethylammonium bromide and oleylamine bromide in toluene to obtain the organoammonium halide solution.

4. The method for preparing thermo-fluorescence-resistant perovskite nanocrystals of metal halide according to claim 3, characterized in that, In the organic ammonium halide solution, the concentration of dodecyl dimethyl ammonium bromide is 0.008~0.02 mmol / mL, and the concentration of oleylamine bromide is 0.02~0.08 mmol / mL.

5. The method for preparing thermo-fluorescence-resistant perovskite nanocrystals of metal halide according to claim 1, characterized in that, In the lead precursor solution, the molar ratio of lead bromide to tetraoctylammonium bromide is 1:2 to 1:

5.

6. A metal halide perovskite nanocrystal resistant to thermo-induced fluorescence quenching, characterized in that, It is prepared by the method for preparing thermo-fluorescent quenching resistant metal halide perovskite nanocrystals according to any one of claims 1 to 5.

7. The thermo-fluorescence-resistant perovskite nanocrystals of metal halide according to claim 6, characterized in that, Its structural components are (FA / Cs)1PbBr3:GA / x-PEA, where FA is a monovalent formamidinium ion, Cs is a monovalent cesium ion, Pb is a divalent lead ion, Br is a monovalent bromide ion, GA is a guanidine ligand, and x-PEA is the organic small molecule amine.

8. The application of the thermo-fluorescence-resistant metal halide perovskite nanocrystals according to claim 6 or 7, characterized in that, Active layer used to prepare electroluminescent or photoluminescent LEDs.

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