Perovskite superlattice, preparation and application in nanoscale light emitting diode

Abstract

The application provides a perovskite superlattice, a preparation method and application in a nanoscale light emitting diode, and the preparation method comprises the following steps: S1, adding B raw materials, an organic ligand, a cosolvent and an organic polymer C into a solvent, and then heating in a vacuum environment to obtain a precursor 1; S2, adding A raw materials and a cosolvent into a solvent, and then heating in a vacuum to obtain a precursor 2; S3, heating the precursor 1 to a specified temperature in an inert gas atmosphere, mixing the precursor 2 with the precursor 1, and then reducing to room temperature at a set cooling rate, and then standing, centrifuging and cleaning to obtain a nanoscale perovskite superlattice; the organic polymer C is at least one of polymethyl methacrylate, low-density polyethylene, polyethylene, linear low-density polyethylene, polyvinylidene fluoride or isotactic polypropylene. The nanoscale light emitting diode has small size and high light emitting efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to a perovskite superlattice, a preparation method and application in a nanoscale light emitting diode, and belongs to the technical field of light emitting diodes. BACKGROUND

[0002] With the continuous development of communication technology, we will enter the information explosion era, and people's demand for ultra-high-definition display is more urgent. Therefore, quantum dot-based Mini-LED, Micro-LED and other ultra-high-resolution display technologies gradually enter the public view, and even some commercial display devices are launched. At present, the highest resolution of the Mini-LED display panel can reach 1000PPI, and the highest resolution of the Micro-LED display panel can reach 1700PPI. However, the resolution that can be achieved by the above display technologies is far from the resolution required by virtual display technology (Virtual Reality, VR) (about 6000PPI). Therefore, it is urgent to develop a display technology with higher resolution.

[0003] One method of developing a display technology with higher resolution is to further reduce the size and pitch of the display pixels and increase the pixel density. When the size of the LED is less than 1 mu m, it is generally considered to be a nanoscale LED, namely Nano-LED. However, the existing Nano-LED usually uses the third generation semiconductor nitride as a light emitting material. Affected by the size effect, the light emitting efficiency decreases sharply as the size becomes smaller, and the internal quantum efficiency is less than 30% when the size is nanoscale. Secondly, its size is 200-500 nm, which is still relatively large and difficult to meet the requirements of high resolution. SUMMARY

[0004] The application provides a perovskite superlattice, a preparation method and application in a nanoscale light emitting diode, which can effectively solve the above problems

[0005] The application is implemented as follows:

[0006] A preparation method of a perovskite superlattice, comprising the following steps:

[0007] S1, adding B raw materials, organic ligands, cosolvents and organic polymers C into a solvent, and then heating in a vacuum environment to obtain a precursor 1;

[0008] S2, adding A raw materials and cosolvents into a solvent, and then heating in a vacuum to obtain a precursor 2;

[0009] S3, heating the precursor 1 to a specified temperature under an inert gas atmosphere, mixing the precursor 2 with the precursor 1, and then reducing to room temperature at a set cooling rate, and then standing, centrifuging and washing to obtain a nanoscale perovskite superlattice;

[0010] The A raw material is at least one of Cs, Rb, methylamine or formamidine salt; the B raw material is at least one of halide of Sn or Pb; the organic polymer C is at least one of polymethyl methacrylate, low-density polyethylene, polyethylene, linear low-density polyethylene, polyvinylidene fluoride or isotactic polypropylene; and the organic ligand is oleylamine.

[0011] As a further improvement, in step S1, the heating temperature is 100-120℃ and the time is 5-60min.

[0012] As a further improvement, in step S2, the heating temperature is 100-150℃ and the time is 5-60min.

[0013] As a further improvement, in step S3, the specified temperature is 140-230℃ and the cooling rate is 0.8-55℃ / min.

[0014] As a further improvement, the mass ratio of the A raw material, the B raw material and the organic polymer C is 15-25:5-10:0.5-4.

[0015] As a further improvement, the size of the perovskite superlattice is ≤100nm.

[0016] A perovskite superlattice prepared by the above method.

[0017] A nanoscale light-emitting diode comprising an ITO transparent conductive glass layer and, sequentially deposited on the ITO transparent conductive glass layer, a hole-electron transport layer, a superlattice light-emitting layer, an electron transport layer and a cathode layer; the superlattice light-emitting layer is made of the above perovskite superlattice.

[0018] As a further improvement, the thickness of the superlattice light-emitting layer is 50-300nm.

[0019] The present application has the following beneficial effects:

[0020] The present application introduces the organic polymer C, uses the bridging force generated by the polymer to arrange the nanocrystals in order, makes the size of the prepared perovskite superlattice ≤100nm, and uses the perovskite superlattice as a light-emitting material of a nanoscale light-emitting diode (Nano-LED), which has super-high light-emitting efficiency and high color purity, and avoids the problems of very low light-emitting efficiency, broadened light spectrum and reduced color purity due to the size effect. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation to the scope. Other related drawings can also be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0022] Figure 1 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 1 of the present application.

[0023] Figure 2 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 2 of the present application.

[0024] Figure 3 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 3 of the present application.

[0025] Figure 4 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 4 of the present application.

[0026] Figure 5 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 5 of the present application.

[0027] Figure 6 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 6 of the present application.

[0028] Figure 7 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 7 of the present application.

[0029] Figure 8 Transmission electron microscope photo of perovskite superlattice provided for the embodiment 8 of the present application.

[0030] Figure 9 Transmission electron microscope photo of perovskite quantum dot provided for the comparative example 1 of the present application.

[0031] Figure 10 Transmission electron microscope photo of perovskite quantum dot provided for the comparative example 2 of the present application.

[0032] Figure 11 Transmission electron microscope photo of perovskite quantum dot provided for the comparative example 3 of the present application.

[0033] Figure 12 Transmission electron microscope photo of perovskite quantum dot provided for the comparative example 4 of the present application.

[0034] Figure 13 Side view of nanometer-scale perovskite light-emitting diode provided for the embodiment of the present application.

[0035] Figure 14 A top view of the nanoscale perovskite light-emitting diode provided by the embodiment of the present application.

[0036] Figure 15 A light-emitting illumination diagram of the nanoscale perovskite light-emitting diode of the embodiment 1 of the present application under the driving of a 5V voltage.

[0037] Figure 16 An electroluminescence spectrum diagram of the nanoscale perovskite light-emitting diode of the embodiment 1 of the present application.

[0038] Figure 17 A curve diagram of the brightness-external quantum efficiency-voltage of the nanoscale perovskite light-emitting diode of the embodiment 1 of the present application. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0040] The embodiment of the present application provides a preparation method of a perovskite superlattice, comprising the following steps:

[0041] S1, adding B raw materials, organic ligands, cosolvents and organic polymers C into a solvent, and then heating in a vacuum environment to obtain a precursor 1;

[0042] S2, adding A raw materials and cosolvents into a solvent, and then heating in a vacuum to obtain a precursor 2;

[0043] S3, heating the precursor 1 to a specified temperature in an inert gas atmosphere, mixing the precursor 2 with the precursor 1, and then reducing to room temperature at a set cooling rate, and then standing, centrifuging and washing to obtain a nanoscale perovskite superlattice;

[0044] The A raw material is at least one of a salt of Cs, Rb, methylamine or formamidine; the B raw material is at least one of a halide of Sn or Pb; the organic polymer C is at least one of polymethyl methacrylate (PMMA), low-density polyethylene (LDPE), polyethylene (PE), linear low-density polyethylene (LLDPE), polyvinylidene fluoride (PVDF) and isotactic polypropylene (IPP); and the organic ligand is oleylamine.

[0045] In the embodiment of the present application, the organic polymer C is added to orderly arrange the nanocrystals by the bridging force generated by the organic polymer C, so as to generate a superlattice, which can be used as a light-emitting material of a Nano-LED, and the problems of very low light-emitting efficiency, spectrum widening and color purity reduction caused by the size effect are avoided.

[0046] The organic polymer C is used to assist the formation of the superlattice, and the organic polymer C is separated after the formation of the superlattice, and the ligand A raw material and the ligand B raw material are always combined on the surface of the nanocrystals, and even after the formation of the superlattice, the ligand A raw material and the ligand B raw material still exist on the surface. The chemical formula of the perovskite superlattice is ABX3, wherein A is at least one of Cs, Rb, methylamine (MA) and formamidine (FA), B is at least one of Sn and Pb, and X is at least one of Cl, Br and I.

[0047] As a further improvement, in step S1, the heating temperature is 100-120℃, and the time is 5-60min. Under this temperature and time condition, the B raw material, the organic ligand and the like can be fully reacted to form the precursor 1, and the concentration of by-products is reduced.

[0048] As a further improvement, in step S2, the heating temperature is 100-150℃, and the time is 5-60min. Under this temperature and time condition, the A raw material can be fully reacted to form the precursor 2, and the concentration of by-products is reduced.

[0049] As a further improvement, in step S3, the specified temperature is 140-230℃, and the cooling rate is 0.8-55℃ / min. Under this condition, the yield of the superlattice is high, which is helpful to improve the light-emitting efficiency of the nanocrystals.

[0050] As a further improvement, in step S3, the standing time is 5-300min. Under this standing time, the formed superlattice can be fully dispersed without being destroyed.

[0051] As a further improvement, the mass ratio of the A raw material, the B raw material and the organic polymer C is 15-25:5-10:0.5-4. Under this mass ratio, the yield of the superlattice is high, and the concentration of by-products is low.

[0052] As a further improvement, the size of the perovskite superlattice is ≤100nm, which is much smaller than the existing superlattice size of 200-500nm. As a light-emitting material for nanoscale light-emitting diodes (Nano-LEDs), it has ultra-high luminous efficiency.

[0053] This invention provides a perovskite superlattice prepared by the above-described method. The perovskite superlattice is a nanoscale quasi-cubic polymer.

[0054] like Figures 13-14 As shown, this embodiment of the invention provides a nano-scale light-emitting diode (Nano-LED), comprising an ITO transparent conductive glass layer and a hole-electron transport layer, a superlattice light-emitting layer, an electron transport layer, and a cathode layer sequentially deposited on the ITO transparent conductive glass layer; the superlattice light-emitting layer is made of the aforementioned perovskite superlattice. This embodiment of the invention is the world's first to utilize a nano-superlattice with a size ≤100nm to fabricate a Nano-LED.

[0055] As a further improvement, the thickness of the superlattice light-emitting layer is 50-300 nm.

[0056] As a further improvement, the hole-electron transport layer material is at least one selected from nano-nickel oxide (NiOx), PEDOT:PSS, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD), 1,2,4,5-tetra(trifluoromethyl)benzene (TFB), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), 2,2′,7,7′-tetra(N,N-di-p-methoxyphenylamine)9,9′-spirodifluorene (spiro-OMeTAD), polyvinylcarbazole (PVK), p-chlorobenzophenone (CBP), tungsten trioxide (WO3), and 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi).

[0057] As a further improvement, the electron transport layer material is at least one selected from (6,6)-phenylcarbon 71-butyrate methyl ester (PCBM), nano-ZnO, 4,6-bis(3,5-di(3-pyridylphenyl)-2-methylpyrimidine (B3PYMPM), sodium bromocresol purple (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen), 3',1”-terphenyl-3,3”-diylpyridine (TMPyPB), 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), and calcium acetylacetonate.

[0058] As a further improvement, the cathode layer material is at least one of nano-Ag, Au, and Al.

[0059] Example 1

[0060] The CsPbBr3perovskite superlattice was prepared by the following steps:

[0061] S11, PbBr2 140 mg, organic ligand oleylamine 1 mL, cosolvent oleic acid 1 mL, and linear low-density polyethylene (LLDPE) 40 mg were added into 10 mL solvent octadecene, heated to 120°C under vacuum for 30 minutes, and precursor 1 was obtained;

[0062] S22, Cs2CO3 400 mg, cosolvent oleic acid 2 mL were added into 10 mL solvent octadecene, heated to 150°C under vacuum for 30 minutes, and precursor 2 was obtained;

[0063] S33, precursor 2 was added to precursor 1 and mixed for 10 seconds after heating precursor 1 to 180°C under nitrogen atmosphere, and the temperature was reduced to room temperature at a rate of 50°C / s; after standing for 1 hour, the precipitate was taken out after centrifugation at a speed of 11000 rpm for 5 minutes, and dispersed in 10 mL n-hexane, and the nanoscale perovskite superlattice was obtained. The transmission electron microscope photograph of the perovskite superlattice is shown in Figure 1 .

[0064] A method for preparing a nanoscale perovskite (green CsPbBr3perovskite) light-emitting diode, comprising:

[0065] S1, using laser etching technology to etch the anode circuit in the ITO layer of the ITO transparent conductive glass;

[0066] S2, dissolving 10 mg of poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly TPD) in 1 ml of organic solvent chlorobenzene to prepare a hole transport ink, and using inkjet printing technology to print a nanoscale (layer thickness of 50 nm) hole electron transport layer film on the ITO layer with the hole transport ink;

[0067] S3, using nano transfer printing technology to deposit a single layer of CsPbBr3perovskite superlattice (thickness of about 100 nm) on the hole electron transport layer film;

[0068] S4, using inkjet printing technology to deposit a nanoscale TPBi electron transport layer with a thickness of 70 nm on the perovskite superlattice;

[0069] S5, using inkjet printing technology to deposit a 500 nm thick patterned circuit layer on the surface of the electron transport layer as the cathode layer.

[0070] Example 2

[0071] CsPbBr 1.5 I1.5 The perovskite superlattice is prepared by the following steps:

[0072] S11, PbBr2 70mg, PbI2 70mg, organic ligand oleylamine 1ml, cosolvent oleic acid 1ml and LLDPE 20mg are added into 10ml solvent octadecene, heated to 100℃ under vacuum environment and stirred for 60 minutes to obtain precursor 1;

[0073] S22, Cs2CO3 400mg, cosolvent oleic acid 2ml are added into 10ml solvent octadecene, heated to 130℃ under vacuum and stirred for 5 minutes to obtain precursor 2;

[0074] S33, under nitrogen atmosphere, precursor 1 is heated to 230℃, then precursor 2 is added into precursor 1 and mixed for 10 seconds, and then cooled to room temperature at a cooling rate of 55℃ / s; and after standing for 300 minutes, the precipitate is taken out by centrifugation at a speed of 11000rpm for 5 minutes, and then added into 10ml n-hexane, and dispersed to obtain nanoscale perovskite superlattice. The transmission electron microscope photograph of the perovskite superlattice is shown in Figure 2 .

[0075] A nanoscale perovskite (red CsPbBr 1.5 I 1.5 A preparation method of a perovskite light-emitting diode, comprising:

[0076] S1, using laser etching technology to etch an anode circuit in an ITO layer of ITO transparent conductive glass;

[0077] S2, dissolving 10mg of hole transport layer material poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly TPD) in 1ml of organic solvent chlorobenzene to prepare hole transport ink, and using inkjet printing technology to print a nanoscale (layer thickness of 50nm) hole electron transport layer film on the ITO layer using the hole transport ink;

[0078] S3, using nano transfer printing technology to deposit a single layer of CsPbBr 1.5 I 1.5 Perovskite superlattice (thickness of about 100nm) on the hole electron transport layer film;

[0079] S4, using inkjet printing technology to deposit a nanoscale TPBi electron transport layer with a thickness of 70nm on the perovskite superlattice;

[0080] S5, using inkjet printing technology to deposit a 500nm thick patterned circuit layer on the surface of the electron transport layer as a cathode layer.

[0081] Example 3

[0082] CsPbBr 1.5 Cl 1.5 The perovskite superlattice is prepared by the following steps:

[0083] S11, PbBr2 70 mg, PbCl2 70 mg, organic ligand oleylamine 1 mL, cosolvent oleic acid 1 mL, and LLDPE 70 mg are added to 10 mL of solvent octadecene, heated to 120°C under vacuum and stirred for 5 min to obtain precursor 1;

[0084] S22, Cs2CO3 400 mg, cosolvent oleic acid 2 mL are added to 10 mL of solvent octadecene, heated to 100°C under vacuum and stirred for 60 min to obtain precursor 2;

[0085] S33, under a nitrogen atmosphere, precursor 1 is heated to 140°C, then precursor 2 is added to precursor 1 and mixed for 10 seconds, and then cooled to room temperature at a cooling rate of 0.8°C / s; and after standing for 5 min, the precipitate is taken out after centrifugation at a speed of 11000 rpm for 5 min, and then dispersed in 10 mL of n-hexane to obtain nanoscale perovskite superlattice. The transmission electron micrograph of the perovskite superlattice is shown in Figure 3 .

[0086] A nanoscale perovskite (blue CsPbBr 1.5 Cl 1.5 A method for preparing a nanoscale perovskite (blue CsPbBr

[0087] S1, using laser etching technology to etch an anode circuit in the ITO layer of ITO transparent conductive glass;

[0088] S2, dissolving 10 mg of hole transport layer material poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly TPD) in 1 ml of organic solvent chlorobenzene to prepare hole transport ink, and using inkjet printing technology to print a nanoscale (layer thickness of 50 nm) hole electron transport layer film on the ITO layer using the hole transport ink;

[0089] S3, using nano transfer printing technology to deposit a single layer of CsPbBr 1.5 Cl 1.5 perovskite superlattice (thickness of about 100 nm) on the hole electron transport layer film;

[0090] S4, using inkjet printing technology to deposit a nanoscale TPBi electron transport layer with a thickness of 70 nm on the perovskite superlattice;

[0091] S5, using inkjet printing technology to deposit a 500 nm thick patterned circuit layer on the surface of the electron transport layer as a cathode layer.

[0092] Example 4

[0093] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 4 .

[0094] Example 5

[0095] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 5 .

[0096] Example 6

[0097] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 6 .

[0098] Example 7

[0099] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 7 .

[0100] Example 8

[0101] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 8 .

[0102] Comparative Example 1

[0103] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown in Figure 9 . The obtained perovskite quantum dots have no superlattice morphology.

[0104] Comparative Example 2

[0105] PbBr2in Example 1 was changed to 140 mg SnBr2, and the rest was the same as Example 1 to prepare red lead-free CsSnBr3perovskite superlattice and nanoscale light-emitting diode. The transmission electron microscope photo of the perovskite superlattice thereof is shown inFigure 10 The obtained perovskite quantum dots have no superlattice morphology.

[0106] Comparative Example 3

[0107] The amount of LLDPE in Example 1 is changed to 80 mg, and the rest is the same as Example 1. The transmission electron microscope photo of the perovskite quantum dots thereof is shown in FIG. 6. Figure 11 The obtained perovskite quantum dots have no superlattice morphology.

[0108] Comparative Example 4

[0109] The amount of LLDPE in Example 1 is changed to 100 mg, and the rest is the same as Example 1. The transmission electron microscope photo of the perovskite quantum dots thereof is shown in FIG. 7. Figure 12 The obtained perovskite quantum dots have no superlattice morphology.

[0110] Figure 15 The luminescent illumination diagram of the nanoscale perovskite light-emitting diode of Example 1 of the present application under the driving of a 5V voltage, Figure 15 shows a single light-emitting pixel size of less than 100 nm, which is much smaller than the size of 200-500 nm reported in the prior art.

[0111] Figure 16 The electroluminescence spectrum diagram of the nanoscale perovskite light-emitting diode of Example 1 of the present application, Figure 16 shows that the Nano-LED prepared at a high voltage of 11V can work normally.

[0112] Figure 17 The luminance-external quantum efficiency-voltage curve diagram of the nanoscale perovskite light-emitting diode of Example 1 of the present application, Figure 17 shows that the single-pixel Nano-LED prepared has an external quantum efficiency of 0.225%, which is much higher than the external quantum efficiency reported in the prior art.

[0113] In summary, the red-green-blue Nano-LED of the present application has the advantages of high light-emitting efficiency, high brightness, super-wide color gamut, and super-high pixel density.

[0114] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of preparing a perovskite superlattice, characterized by, The method comprises the following steps: S1, adding B raw material, organic ligand, cosolvent and organic polymer C into solvent, and then heating under vacuum environment to obtain precursor 1; S2, adding A raw material and cosolvent into solvent, and then heating under vacuum to obtain precursor 2; S3, heating the precursor 1 to a specified temperature under inert gas atmosphere, mixing the precursor 2 with the precursor 1, and then reducing to room temperature at a set cooling rate, and then standing, centrifuging and cleaning to obtain nano-sized perovskite superlattice; The A raw material is at least one of salt of Cs, Rb, methylamine or formamidine; the B raw material is at least one of halide of Sn or Pb; the organic polymer C is low density polyethylene or linear low density polyethylene; and the organic ligand is oleylamine; In step S1, the heating temperature is 100-120℃, and the time is 5-60 min; In step S2, the heating temperature is 100-150℃, and the time is 5-60 min; In step S3, the specified temperature is 140-230℃, and the cooling rate is 0.8-55℃ / min; The mass ratio of A raw material, B raw material and organic polymer C is 15-25:5-10:0.5-4.

2. The method of claim 1, wherein the perovskite superlattice is prepared by a method comprising: The size of the perovskite superlattice is ≤100 nm.

3. A perovskite superlattice prepared by the method of any one of claims 1-2.

4. A nanoscale light emitting diode, characterized in that, The device comprises an ITO transparent conductive glass layer and a hole electron transport layer, a superlattice light-emitting layer, an electron transport layer and a cathode layer deposited on the ITO transparent conductive glass layer in sequence; the superlattice light-emitting layer is prepared from the perovskite superlattice of claim 3.

5. The nanoscale light emitting diode of claim 4, wherein, The thickness of the superlattice light-emitting layer is 50-300 nm.

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