Hierarchical shell-stabilized colloidal perovskite nanocrystals, manufacturing method therefor, light-emitting film comprising same, and method for forming fine pattern of light-emitting film

Abstract

The present invention relates to hierarchical shell-stabilized colloidal perovskite nanocrystals, a manufacturing method therefor, a light-emitting film comprising same, a method for forming a fine pattern of the light-emitting film, and light-emitting applications thereof. The colloidal perovskite nanocrystals according to the present invention can provide a color-tunable colloidal perovskite nanocrystal film and a method for improving luminous efficiency and stability of the fine pattern, by constructing a hierarchical shell structure of core-shell-shell-shell.

Description

Hierarchical shell-stabilized colloidal perovskite nanocrystals, a method for manufacturing the same, a light-emitting film comprising the same, and a method for forming a micropattern of a light-emitting film

[0001] The present invention relates to hierarchical shell-stabilized colloidal perovskite nanocrystals, wherein the perovskite nanocrystal core is protected through a hierarchically formed first inorganic shell, a second inorganic shell, and an organic / polymer shell to heal surface defects and prevent damage caused by solvents or moisture, and to the hierarchical shell-stabilized colloidal perovskite nanocrystals capable of trapping excitons to improve luminescence efficiency, a method for manufacturing the same, a luminescent film comprising the same, a method for forming a micropattern of the luminescent film, and luminescence applications thereof.

[0002] Halide perovskites (hereinafter referred to as 'perovskites') are broadly classified into three-dimensional bulk crystals, quasi-2D crystals, and colloidal nanocrystals depending on the crystal size and type. Perovskite luminescent materials are ABX 3( 3D), A4BX 6( 0D), AB2X 5( 2D), A2BX 4( 2D), A2BX6(0D), A2B + B 3+ X 6( 3D), A3B2X 9( 2D) or A n-1 B n X 3n+1( It has a quasi-2D)(n is an integer between 2 and 6) structure, where A is a monovalent cation, B is a metallic material, and X is a halogen element.

[0003] More specifically, perovskite nanocrystals (PeNCs) are receiving great attention due to their narrow emission band emission, color tuning across the entire visible spectrum, and high photoluminescence quantum yield (PLQY). In addition, it has been reported that perovskite nanocrystals have low crystallization energy and inherent defect tolerance, making it possible to easily produce perovskite nanocrystals with excellent optical properties at room temperature without protection by an inert gas.

[0004] Due to these ease of manufacturing, perovskite nanocrystals offer significant technical and cost advantages over conventional inorganic quantum dot technology. Since light emitters containing these perovskite nanocrystals can help realize low-cost displays with high quality and efficiency, perovskite nanocrystals possess broad application prospects and research value as a new type of light-emitting quantum dot material.

[0005] However, the structural and optical stability of colloidal perovskite nanocrystals are poor, and their fluorescence efficiency rapidly deteriorates and decreases in response to environmental stimuli such as light, heat, humidity, and polar solvents. The main reasons for the poor stability of perovskite nanocrystals are, firstly, that they possess a fragile ionic crystal structure that is easily decomposed by polar solvents such as water, and secondly, that the ionic interactions or coordination bonds between the core and surface organic ligands are weak, causing the ligands to detach easily and create surface defects in the quantum dots. Water, oxygen, or polar solvents can be absorbed at exposed defect sites, causing phase changes or degradation of the perovskite nanocrystals, which in turn reduces photoluminescence efficiency.

[0006] Current methods to enhance the stability of perovskite nanocrystals include surface defect passivation, core-shell structural design, the use of ligands with strong bonding forces, and protection through polymer encapsulation. These methods have improved the optical and structural stability of perovskite nanocrystals to some extent, and some papers have demonstrated LCD displays based on perovskite nanocrystal enhancement films, similar to quantum dot enhancement films (QDEFs). For example, perovskite nanocrystal composites fabricated based on glass, silicon dioxide (silica), metal-organic frameworks (MOFs), and molecular sieves exhibit excellent stability. However, these methods generally weaken the solution processability of perovskite nanocrystals and also exhibit lower photoluminescence quantum yield (PLQY) due to the lack of surface passivation by organic ligands.

[0007] In contrast, solution-prepared colloidal perovskite nanocrystals can have their surfaces effectively modified through organic ligands. The presence of ligands ensures high PLQY and excellent solution processability, enabling high-resolution patterning via printing or photolithography processes for use in micro-LED displays.

[0008] However, the stability of perovskite nanocrystal-based photoluminescence down-conversion enhancement films in standard aging tests, including tests in high temperature, high humidity, and high light flux environments, needs to be further improved.

[0009] Furthermore, while mixed halide perovskite compositions must be used to achieve pure blue and pure red perovskite luminescence in full-color displays, photo-induced halide segregation presents a problem in that it degrades the spectral stability of mixed halide perovskite nanocrystals containing iodine (I) or chloride (Cl), which are added to achieve red and blue light. Therefore, the development of color-tunable colloidal perovskite nanocrystal films with high luminescence efficiency and stability is essential for the commercialization of perovskite nanocrystals.

[0010] [Prior Art Literature]

[0011] [Patent Literature]

[0012] U.S. Patent Publication No. 2022 / 0085301A

[0013] [Non-patent literature]

[0014] Nano Lett. 2015, 15, 3692-3696

[0015] Nature Photonics 2021, 15, 148-155

[0016] To solve the aforementioned problems, the present invention provides colloidal perovskite nanocrystals having excellent luminescence efficiency and stability, a method for manufacturing the same, a luminescent film containing the same, a method for forming a micropattern of the luminescent film, and luminescence applications thereof.

[0017] One aspect of the present invention for achieving the above-mentioned objective relates to a colloidal perovskite nanocrystal having a hierarchical core-shell-shell-shell structure, characterized by comprising: a perovskite nanocrystal core; a first inorganic shell surrounding the perovskite nanocrystal core; a second inorganic shell surrounding the first inorganic shell; and an organic / polymer shell surrounding the second inorganic shell.

[0018] The above perovskite nanocrystal core is manufactured by a solution process and coated with a ligand, and can be formed with a diameter that exceeds the exciton Bohr diameter, unlike conventional quantum dots.

[0019] The above perovskite luminescent materials are ABX3 (3D), A4BX6 (0D), AB2X5 (2D), A2BX4 (2D), A2BX6 (0D), A2B + B 3+ X6(3D), A3B2X9(2D) or A n-1 B n X 3n+1 It has a (quasi-2D) structure (n is an integer between 2 and 6), where A is a monovalent cation (a monovalent metal or monovalent organic cation), B is a metallic material, and X is a halogen element. Perovskite luminescent materials can be used as materials for nanocrystalline cores.

[0020] The above perovskite nanocrystal core comprises one or more materials selected from CsBX3, RbBX3, MABX3, FABX3, CsRbBX3, RbFAPbX3, RbMAPbX3, RbGAPbX3, CsFABX3, CsMABX3, MAFABX3, CsGABX3, FAGABX3, RbCsFABX3, RbCsMABX3, RbMAFABX3, RbCsGABX3, RbFAGABX3, CsMAFAPbX3, and CsRbMAFAPbX3, wherein X is chlorine, bromine, iodine, or a mixture thereof, B is at least one metal element selected from Pb, Sn, Ge, Bi, Sb, Ag, Na, In, Bi, Mg, and Mn, MA is methylamine, and FA is It is formamidine, and the above GA may be guanidinium.

[0021] When the perovskite nanocrystal core and the first inorganic shell are epitaxially grown together, the lattice mismatch between the perovskite nanocrystal core and the first inorganic shell may be greater than 0% and less than or equal to 25%. Preferably, it may be 1 to 7%. More specifically, it may be 1, 2, 3, 4, 5, 6, and 7%. More preferably, it may be 1 to 3%.

[0022] The above-mentioned first inorganic shell can form a type-I heterojunction with a perovskite nanocrystal core.

[0023] The first inorganic shell may have a band gap 0.1 to 5.0 eV larger than the band gap of the perovskite nanocrystal core.

[0024] The first inorganic shell may include at least one selected from metal sulfates and metal sulfides.

[0025] The bandgap of the second inorganic shell above may be 3.0 eV to 10.0 eV without absorption of visible light.

[0026] The second inorganic shell may include one or more selected from the group consisting of SnO2, ZrO2, NiO, SiO2, TiO2, and Al2O3. For example, among the insulators that can be used as inorganic shells, SiO2, Al2O3, and H f The band gaps of O2 are 9.1 eV, 8.8 eV, and 5.3-6.0 eV, respectively.

[0027] The band gap of the above organic / polymer shell may be 3.0 eV to 10.0 eV without absorption of visible light.

[0028] The above organic / polymer shell may comprise one or more selected from the group consisting of polysiloxane (siloxane polymer) or siloxane, polystyrene (PS), polymethyl methacrylate (PMMA), polyvinylphenol (PVP), polyvinylidene fluoride (PVDF), polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET).

[0029] Another aspect of the present invention for achieving the above-mentioned objective comprises the steps of: forming a perovskite nanocrystal (PeNC) core; reacting the core with a first inorganic shell precursor to form a perovskite nanocrystal core-first inorganic shell structure in which a first inorganic shell is arranged to surround the core; and reacting the perovskite nanocrystal core-first inorganic shell with a second inorganic shell precursor to form a perovskite nanocrystal core-first inorganic shell-second inorganic shell structure in which a second inorganic shell is arranged to surround the first inorganic shell. The present invention relates to a method for manufacturing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized by comprising the step of reacting the above-mentioned perovskite nanocrystal core-first inorganic shell-second inorganic shell with an organic / polymer ligand precursor to form a perovskite nanocrystal core-first inorganic shell-second inorganic shell-organic / polymer shell structure in which the organic / polymer shell is arranged to surround the second inorganic shell.

[0030] The core-shell interface and shell-shell interface can be bonded by coordination bonding, covalent bonding, or ionic bonding.

[0031] The thickness of the first inorganic shell may be 0.1 nm to 100 nm. More preferably, it may be 0.5 nm to 20 nm, and more specifically, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 11 nm, 13 nm, 15 nm, 17 nm, or 20 nm.

[0032] The thickness of the second inorganic shell may be 0.1 nm to 100 nm. More preferably, it may be 0.5 nm to 20 nm, and more specifically, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 11 nm, 13 nm, 15 nm, 17 nm, or 20 nm.

[0033] The thickness of the above organic / polymer shell may be 0.1 nm to 100 nm. More preferably, it may be 0.5 nm to 20 nm, and more specifically, it may be 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 11 nm, 13 nm, 15 nm, 17 nm, or 20 nm.

[0034] The above colloidal perovskite nanocrystals may be perovskite nanocrystal (PeNC) particles with a stabilized PeNC / PbSO4 / SiO2 / siloxane structure having a hierarchical core-shell-shell-shell structure.

[0035] To stabilize the above colloidal perovskite nanocrystals, alkyl halides, amine ligands, organic ammonium ligands, inorganic ligands, or organic acids (carboxylic acids or phosphonic acids) may be used as surfactants. Representatively, the surfactants may include oleylamine as an amine ligand and oleic acid as a carboxylic acid.

[0036] The step of forming the perovskite nanocrystalline core may include: a process of forming a first solution by mixing PbBr2 and an organic ligand in a first solvent; a process of forming a second solution by mixing Cs and a surfactant in a second solvent; a process of forming a CsPbBr3 perovskite nanocrystalline core by mixing the first solution and the second solution; a process of purifying the CsPbBr3 perovskite nanocrystalline core; and a process of dispersing the CsPbBr3 perovskite nanocrystalline core in a third solvent.

[0037] The above method for manufacturing perovskite nanocrystals may include the step of reacting (APTES)2SO4 with perovskite nanocrystals to obtain a PeNC / PbSO4 / APTES core-shell structure; and the step of adding TMOS (tetraethyl orthosilicate) or TEOS (tetraethyl orthosilicate) to the PeNC / PbSO4 / APTES core-shell structure to obtain stabilized PeNC / PbSO4 / SiO2 perovskite nanocrystals with a double-shell structure.

[0038] A (APTES)2SO4 precursor can be prepared by reacting the above APTES and H2SO4 in a non-polar solvent at a molar ratio of 2:1.

[0039] Another aspect of the present invention for achieving the above-mentioned objective provides a method for manufacturing a hierarchical core-shell-shell-shell PeNC / PbSO4 / SiO2 / siloxane light-emitting film, characterized by forming the film by applying a mixture comprising double-shell structured PeNC / PbSO4 / SiO2 perovskite nanocrystals and a siloxane polymer resin as a bar coating on a base substrate and then photopolymerizing it.

[0040] The above siloxane polymer resin can be formed by condensing diphenylsilanediol and 3-methacryloxypropyltrimethoxysilane in the presence of a Ba(OH)2 catalyst and then adding a photoinitiator.

[0041] Another aspect of the present invention for achieving the above-mentioned objective relates to a method for forming a micropattern of a siloxane polymer hybrid resin and a colloidal perovskite nanocrystal having a hierarchical core-shell-shell-shell structure, comprising the step of directly patterning the light-emitting film containing the colloidal perovskite nanocrystal having the hierarchical core-shell-shell-shell structure through photolithography and then developing the light-emitting film.

[0042] The pixel size of the above micropattern may be 500 nm to 5 mm, and more specifically, may be 500 nm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 500 μm, 1 mm, 2 mm, or 5 mm. Additionally, for AR / VR applications, a size of 500 nm to 5 μm is preferred.

[0043] The above perovskite nanocrystals can be photocrosslinked by mixing them with a ligand crosslinking agent (LiXer).

[0044] The above-mentioned ligand crosslinking agent is 2-LiXer(ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate)); 4-LiXer(2,2-bis(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate), IP-4-LiXer(2,2-bis(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5-trifluoro-6-isopropylbenzoate))); 6-LiXer(2-(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)-2-((3-((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)-2,2-bis(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)propoxy)methyl)propane-1,3-diylbis(4-azido-2,3,5,6-tetrafluorobenzoate)); It may be one or more selected from the group consisting of IP-6-LiXer(2-((3-((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)-2,2-bis(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propoxy)methyl)-2-(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5-trifluoro-6-isopropylbenzoate)).

[0045] Another aspect of the present invention for achieving the above-mentioned objective relates to a luminescent film produced by a method for producing a PeNC / PbSO4 / SiO2 / siloxane luminescent film having the above-mentioned hierarchical core-shell-shell-shell structure.

[0046] Another aspect of the present invention for achieving the above-mentioned objective relates to a micropattern produced by a method for forming a micropattern of a colloidal perovskite nanocrystal with a hierarchical core-shell-shell-shell structure and a siloxane polymer hybrid resin.

[0047] The above colloidal perovskite nanocrystals can be used as an electroluminescent LED, a single photon emitter, or an emitter for an oxygen saturation meter.

[0048] The above-mentioned light-emitting film or micro-pattern can be used as a color conversion layer for Liquid Crystal Display (LCD), Mini Light-Emitting Diode (LED), Micro LED, Organic Light-Emitting Diodes (OLEDs), and Virtual Reality / Augmented Reality (VR / AR) display systems.

[0049] The colloidal perovskite nanocrystals according to the present invention can construct a core-shell-shell-shell hierarchical shell structure (Hierarchical-Shelled, HS) to provide a color-tunable colloidal perovskite nanocrystal film and a method to improve the luminescence efficiency and stability of fine patterns. In addition, CsPbBr3 perovskite nanocrystal films with a PLQY content exceeding 84% can be manufactured. T of the HS-CsPbBr3 perovskite nanocrystals according to the present invention under conditions of 60°C and 90% relative humidity 90The lifetime exceeds 3,211 hours and the photostability exceeds 10,000 hours. According to the method of the present invention, it is applicable to stabilizing an organic-inorganic hybrid MAPbBr3 film having pure green emission of 529 nm, such that under aging conditions of 60°C, 90% relative humidity and / or blue light, PLQY approaches 100% and T 90 The lifetime can exceed 2,000 hours. In addition, halide separation can be suppressed in mixed halide blue and red emitting perovskite nanocrystals with photostability of 2,000 hours each. Furthermore, this structure can significantly reduce the toxicity of the nanocrystal film by successfully preventing lead leakage. Using these colloidal perovskite nanocrystals, efficient, stable, color-tunable, and environmentally friendly perovskite emitters for commercial applications can be developed.

[0050] FIG. 1 is a schematic diagram showing the structure of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0051] FIG. 2 is a diagram showing the energy alignment of a core, a first inorganic shell, a second inorganic shell, and an organic / polymer shell constituting a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0052] FIG. 3(a) is a schematic diagram showing the process of forming colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure based on a spherical shape according to one embodiment of the present invention, and FIG. 3(b) is a schematic diagram showing the process of forming colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure based on a cubic shape.

[0053] FIG. 4 is a schematic diagram illustrating a method for manufacturing CsPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystals with a hierarchical shell structure according to one embodiment of the present invention.

[0054] FIG. 5 is a flowchart illustrating a method for manufacturing a CsPbBr3 core constituting a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0055] Figure 6 is the molecular structure of (APTES)2SO4 according to one embodiment of the present invention.

[0056] Figure 7 is a diagram showing the band gaps of CsPbBr3, PbSO4, SiO2, and siloxane.

[0057] FIG. 8 is a schematic diagram illustrating a perovskite nanocrystal stabilized with a hierarchical shell interface structure according to one embodiment of the present invention.

[0058] FIG. 9 is a graph showing the photoluminescent spectra of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0059] FIG. 10 is a TEM image analyzing the morphological change during the formation of a perovskite nanocrystal with a hierarchical shell structure according to one embodiment of the present invention.

[0060] Figure 11 is a High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) image of a hierarchical shell CsPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystal according to one embodiment of the present invention.

[0061] FIG. 12 is a graph showing the analysis by X-ray Photoelectron Spectroscopy (XPS) of a core-shell-shell-shell structured perovskite nanocrystal according to one embodiment of the present invention.

[0062] FIG. 13 is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of (a) a CsPbBr3 core and (b) a CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal according to one embodiment of the present invention.

[0063] Figure 14 is a STEM-EDS mapping image of a CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal according to one embodiment of the present invention.

[0064] FIG. 15 is (a) an optical image and (b) a fluorescent image of a CsPbBr3 / siloxane resin and a hierarchical shell HS-CsPbBr3 / siloxane according to one embodiment of the present invention.

[0065] FIG. 16(a) is a graph showing the interrelationship between viscosity and shear rate for pure siloxane, CsPbBr3 / siloxane, and HS-CsPbBr3 / siloxane according to one embodiment of the present invention, and FIG. 16(b) is a graph showing the molecular weight test results by gel permeation chromatography (GPC) according to one embodiment of the present invention.

[0066] FIG. 17(a) is a Si-29 nuclear magnetic resonance (NMR) graph of CsPbBr3 / siloxane and HS-CsPbBr3 / siloxane according to one embodiment of the present invention, and FIG. 17(b) is a chemical formula of a silicon atom.

[0067] FIG. 18 illustrates the fluorescence spectrum of a perovskite nanocrystal / siloxane hybrid film according to one embodiment of the present invention.

[0068] FIG. 19 is a graph showing the results of an aging stability test of CsPbBr3 / siloxane, CsPbBr3 / PbSO4 / siloxane, and CsPbBr3 / PbSO4 / APTES perovskite nanocrystalline films according to one embodiment of the present invention.

[0069] FIG. 20 is a graph showing the aging stability of a hierarchical shell-stabilized HS-CsPbBr3 / PeNC / siloxane hybrid film according to one embodiment of the present invention.

[0070] FIG. 21 is a graph showing the stability over time of a hierarchical shell for stabilizing a MAPbBr3PeNC / siloxane hybrid film according to one embodiment of the present invention.

[0071] FIG. 22(a) shows blue light (23 mW / cm²) according to one embodiment of the present invention. 2 Blue CsPbCl stabilized under irradiation 1.4 Br 1.6 This is a graph showing the photostability of the hierarchical shell of the PeNC / siloxane film, and FIGS. 22(b) and FIGS. 22(c) are CsPbCl 1.4 Br 1.6 / Siloxane film and HS-CsPbCl 1.4 Br 1.6 This is a graph showing the spectral stability corresponding to each siloxane film.

[0072] FIG. 23 is a red CsPbI according to an embodiment of the present invention 1.8 Br 1.2 A graph plotting the time-dependent stability (PL peak: 627 nm) of a hierarchical shell for stabilizing perovskite nanocrystals, where Fig. 23(a) shows PLQY and Fig. 23(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 It represents ).

[0073] FIG. 24 is a graph showing the time-dependent stability (PL peak: 656 nm) of a hierarchical shell for stabilizing deep red CsPbI2Br perovskite nanocrystals according to an embodiment of the present invention, where FIG. 24(a) shows PLQY and FIG. 24(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 It represents ).

[0074] FIG. 25 is a graph illustrating the time-dependent stability (PL peak: 687 nm) of a hierarchical shell for stabilizing CsPbI3 perovskite nanocrystals according to an embodiment of the present invention, where FIG. 25(a) shows PLQY and FIG. 25(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2It represents ).

[0075] Fig. 26 is a graph showing the time-dependent stability (PL peak: 783 nm) of a hierarchical shell for stabilizing FAPbI3 perovskite nanocrystals, where Fig. 26(a) shows PLQY and Fig. 26(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 It represents ).

[0076] Fig. 27 is Cs 0.5 FA 0.5 A graph plotting the time-dependent stability (PL peak: 737 nm) of a hierarchical shell for stabilizing PbI3 perovskite nanocrystals, where Fig. 27(a) shows PLQY and Fig. 27(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 It represents ).

[0077] FIG. 28 is a schematic diagram showing the process of performing hybrid photolithography of hierarchical shell-stabilized perovskite nanocrystals (HS-PeNC) and siloxane according to one embodiment of the present invention.

[0078] FIG. 29 is a schematic diagram showing the process of performing photolithography of stabilized perovskite nanocrystals (HS-PeNC) using a ligand crosslinking agent (Lixer) according to one embodiment of the present invention.

[0079] FIG. 30 is a graph showing the results of a biocompatibility evaluation of an HS-CsPbBr3 / siloxane film using C2C12 mouse myoblast cells according to one embodiment of the present invention.

[0080] FIG. 31 is a schematic diagram illustrating the configuration (a) of a hierarchical shell-stabilized perovskite nanocrystal (HS-PeNC) color conversion layer film for a backlight display, the white light spectrum (b) of a green and red HS-PeNC-based tablet, and the green, red, and blue images (c) of the perovskite tablet, respectively.

[0081] FIG. 32 is a schematic diagram showing the structure of a color conversion layer pattern of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure for a high-resolution display according to one embodiment of the present invention.

[0082] FIG. 33(a) is a pixelated electroluminescent device comprising perovskite nanocrystals (HS-PeNCs) with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention, FIG. 33(b) is a quantum emitter, and FIG. 33(c) is a schematic diagram showing perovskite nanocrystals (HS-PeNCs) with a hierarchical core-shell-shell-shell structure used in such a luminescent device.

[0083] FIG. 34 is a schematic diagram showing the structure of an oxygen saturation meter comprising perovskite nanocrystals (HS-PeNCs) of a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0084] Embodiments of the present invention will be described in more detail below with reference to the drawings. In the following description, if it is determined that a detailed description of known contents or configurations related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0085] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0086] While the present invention allows for various modifications and variations, specific embodiments are illustrated in the drawings and will be described in detail below. However, it is not intended to limit the invention to the particular forms disclosed, but rather the invention includes all modifications, equivalents, and substitutions consistent with the spirit of the invention as defined by the claims.

[0087] When an element such as a layer, region, or substrate is referred to as existing "on" another component, it can be understood that this exists directly on the other element, or that an intermediate element may exist between them.

[0088] When a part is said to "include" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0089] All numerical ranges representing physical property values, dimensions, reaction conditions, etc. of the components described in this specification should be understood as being modified by the term "approximately" in all cases unless otherwise specified.

[0090] In this specification, the description that one component is formed on the upper or lower part of another component includes both cases where one component is formed directly on the upper or lower part of another component or indirectly through another component.

[0091] In this specification, singular expressions are interpreted to include singular or plural forms as interpreted in context unless otherwise specified.

[0092]

[0093] Perovskite nanocrystals with a hierarchical core-shell-shell-shell structure

[0094] One aspect of the present invention provides perovskite nanocrystals with a hierarchical core-shell-shell-shell structure.

[0095] FIG. 1 is a schematic diagram showing the structure of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0096] Referring to FIG. 1, the perovskite nanocrystal of the hierarchical core-shell-shell-shell structure of the present invention may comprise a perovskite nanocrystal core (10), a first inorganic shell (20) surrounding the perovskite nanocrystal core (10), a second inorganic shell (30) surrounding the first inorganic shell (20), and an organic / polymer shell (40) surrounding the second inorganic shell (30).

[0097] As shown in FIG. 2, the first inorganic shell (20) must form a Type-I heterojunction (or heterojunction) with the perovskite nanocrystal core (10), and after forming the perovskite nanocrystal core (10)-first inorganic shell (20), a second inorganic shell (30) is placed in a manner surrounding the first inorganic shell (20). After forming the perovskite nanocrystal core (10), the first inorganic shell (20), and the second inorganic shell (30), an organic / polymer shell (40) is placed in a manner surrounding the second inorganic shell (30) to form a perovskite nanocrystal core (10)-first inorganic shell (20)-second inorganic shell (30)-organic / polymer shell structure (40). Here, in order to obtain the effect of confining excitons (or electron-hole pairs) to the perovskite nanocrystal core (10), the band gap of the first inorganic shell (20) and the organic / polymer shell (40) must be at least 0.1 to 5.0 eV larger than the band gap of the perovskite nanocrystal core (10). Here, in the case of a Type-I heterojunction, the band gap of the inorganic shell must be larger than that of the perovskite nanocrystal core (10), and when compared by considering the energy level relative to the vacuum level, the conduction band minimum (CBM) of the nanocrystal core (10) must be lower than the CBM of the inorganic shell, and the valence band maximum (VBM) of the nanocrystal core (10) must be higher than the VBM of the inorganic shell. Here, the second inorganic shell (30) and the organic / polymer shell (40) must have an energy band gap of 3.0 eV or more, preferably 4.0 eV or more, and more preferably 5.0 eV or more. This is to ensure that the band gap is sufficiently large so as not to absorb visible light emitted from the perovskite nanocrystal core (10).

[0098]

[0099] When the perovskite nanocrystal core (10) and the first inorganic shell (20) are epitaxially grown together, a lattice mismatch of 25% or less may be formed between the perovskite nanocrystal core (10) and the first inorganic shell (20). This allows for effective protection of surface defects of the perovskite nanocrystal core (10), thereby improving light stability and luminescence efficiency. Lattice mismatch refers to the degree of similarity of the lattice constants of the perovskite nanocrystal core (10) and the first inorganic shell (20). The lattice mismatch coefficient can be calculated using the following equation (1).

[0100] Lattice mismatch (%) = [(a₁-a₂) / a₂] × 100 … … Equation (1)

[0101] Here, a₁ is the lattice parameter of the perovskite nanocrystal core (10), and a2 is the lattice parameter of the first inorganic shell (20).

[0102] The nanocrystalline core (10)-first inorganic shell (20)-second inorganic shell (30)-organic / polymer shell structure (40) according to the present invention is a hierarchical core-shell-shell-shell structure, and this structure can improve the stability and photoluminescence efficiency of the nanocrystalline core (10) by protecting the nanocrystalline core (10) with multiple shells. Specifically, the nanocrystalline core (10)-first inorganic shell (20)-second inorganic shell (30)-organic / polymer shell (40) structure has a structural feature in which an inorganic layer composed of PbSO4 and SiO2 is combined with a siloxane organic shell. At this time, the bond between the first inorganic shell (20) composed of PbSO4 and the second inorganic shell (30) composed of SiO2 forms a coordinate bond, and the bond between the second inorganic shell (30) and the siloxane organic / polymer shell (40) forms a covalent bond. The perovskite nanocrystals of the hierarchical core-shell-shell-shell structure having such a bonding structure can stably protect the nanocrystal core (10) and exhibit excellent environmental resistance to light, heat, moisture, polar solvents, etc. compared to the conventional core-shell structure. In addition, the lattice mismatch between the nanocrystal core (10) and the first inorganic shell (20) is formed at 25% or less, providing excellent stability, photoluminescence efficiency, and solution processability.

[0103]

[0104] FIG. 3(a) is a schematic diagram illustrating the process of forming colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure based on a spherical shape according to one embodiment of the present invention, and FIG. 3(b) is a schematic diagram illustrating the process of forming colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure based on a cubic shape. As illustrated in FIG. 3, a method for manufacturing perovskite nanocrystals having a hierarchical core-shell-shell-shell structure comprises the following four steps: 1) preparing a perovskite nanocrystal core (S10); 2) reacting the perovskite nanocrystal core with a first inorganic shell precursor to form a PeNC core-first inorganic shell structure in which the first inorganic shell is arranged to surround the perovskite nanocrystal (PeNC) core (S20); 3) a step (S30) of forming a PeNC core-first inorganic shell-second inorganic shell structure in which the second inorganic shell is arranged to surround the first inorganic shell by reacting the PeNC core-first inorganic shell-second inorganic shell precursor; 4) a step (S40) of forming a PeNC core-first inorganic shell-second inorganic shell-organic / polymer shell structure in which the organic / polymer shell is arranged to surround the first inorganic shell by reacting the PeNC core-first inorganic shell-second inorganic shell with an organic / polymer shell precursor. According to the present invention, the PeNC core-first inorganic shell-second inorganic shell structure formed in the intermediate step (S30) also has the characteristic of having a hierarchical structure of core-shell-shell.

[0105] Conventional inorganic quantum dots have a size smaller than the exciton Bohr diameter, making it difficult to control the size of the quantum dots consistently. Furthermore, color purity and spectrum are significantly affected by the size and size distribution. As the size decreases, defects on the crystal surface increase, which leads to a disadvantage of reduced efficiency. To solve this problem, the present invention provides a nanocrystal having a size larger than the exciton Bohr diameter so as to exhibit maximum luminescence efficiency without being affected by quantum confinement effects. The exciton Bohr diameter can be calculated using the effective mass value of the metal halide perovskite and the following equation (2).

[0106] … … Equation (2)

[0107] Here, r represents the exciton Bohr radius, α0 is the hydrogen Bohr radius (0.053 nm), and ε r ε₀ is the dielectric constant, m₀ is the free electron mass, and μ is the reduced mass, so μ = (m₀ h × m e ) / (m h + m e It is defined as ). Here, m e is the effective electron mass, m h is the effective hole mass. Also, the bore diameter means twice the bore radius.

[0108] Specifically, the perovskite nanocrystal core (10) may have a size greater than or less than an exciton bore diameter (about 10 nm for MAPbBr3-based and about 7 nm for CsPbBr3-based). For example, the size of the perovskite nanocrystal core (10) must be equal to or greater than the following exciton bore diameter. The exciton bore diameters are 7nm, 7.5nm, 8nm, 8.3nm, 8.5nm, 8.7nm, 9nm, 9.3nm, 9.5nm, 9.7nm, 10nm, 10.3nm, 10.5nm, 10.7nm, 11nm, 11.3nm, 11.5nm, 11.7nm, 12nm, 12.3nm, 12.5nm, 12.7nm, 13nm, 13.3nm, 13.5nm, 13.7nm, 14nm, 14.3nm, 14.5nm, 14.7nm, 15nm, 15.3nm, 15.5nm, 15.7nm, 16nm, 16.5nm, 17nm, 17.5nm, It may be 18nm, 18.5nm, 19nm, 19.5nm, 20nm, 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm, or 30nm. Preferably, it may be 7nm or more and 25nm or less. More preferably, it may be 10nm or more and 20nm or less. More preferably, it may be 10nm or more and 15nm or less.

[0109] FIG. 4 is a schematic diagram illustrating a method for manufacturing CsPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystals with a hierarchical shell structure according to one embodiment of the present invention.

[0110] FIG. 5 is a flowchart showing a method for manufacturing a CsPbBr3 core constituting a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention, and FIG. 6 is a molecular structure of (APTES)2SO4 according to one embodiment of the present invention.

[0111] Referring to FIG. 5, the step of forming the perovskite nanocrystalline core may include a process of forming a first solution by mixing PbBr2 and an organic ligand in a first solvent, a process of forming a second solution by mixing Cs and a surfactant in a second solvent, a process of forming a CsPbBr3 perovskite nanocrystalline core by mixing the first solution and the second solution, a process of purifying the CsPbBr3 perovskite nanocrystalline core, and a process of dispersing the CsPbBr3 perovskite nanocrystalline core in a third solvent.

[0112] The first solvent, the second solvent, and the third solvent may be one or more selected from toluene, cyclohexene, dimethylformamide, gammabutyrolactone, N-methylpyrrolidone, dimethylsulfoxide, dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, and xylene.

[0113] The above surfactant may include an organic ligand formed on the surface of the perovskite nanocrystal. According to the present invention, alkyl halides, amine ligands, organic ammonium ligands, inorganic ligands, or organic acids (carboxylic acids or phosphonic acids) may be used as ligands to stabilize the colloidal perovskite nanocrystal. Representatively, the surfactant may include oleylamine, an amine ligand, and oleic acid, a carboxylic acid. This surfactant acts as a ligand surrounding the surface of the synthesized perovskite nanocrystal, attaching to the surface through ionic or coordination bonding, and contributes to increasing dispersibility. The ligand surrounds the surface of the perovskite nanocrystal and can repeatedly attach and detach due to dynamic binding.

[0114] The above amine ligand may be selected from N,N-diisopropylethylethylamine, ethylenediamine, hexamethylenetetramine, methylamine, N,N,N',N'-tetramethylethylenediamine, triethylamine, diethanolamine, and 2,2-(ethylenedioxyl)bis-(ethylamine) but is not limited thereto.

[0115] The above organic acid includes a carboxylic acid and a phosphonic acid, and the carboxylic acid is 4,4'-Azobis(4-cyanovaleric acid), acetic acid, 5-aminosalicylic acid, acrylic acid, L-aspentic acid, 6-bromohexanoic acid, bromoacetic acid, dichloroacetic acid, ethylenediaminetetraacetic acid, isobutyric acid, itaconic acid, maleic acid, The phosphonic acid may be selected from r-maleimidobutyric acid, L-Malic acid, 4-nitrobenzoic acid, 1-pyrenecarboxylic acid, hexanoic acid, octanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, hexadecanoic acid, octadecanoic acid, and oleic acid, and the phosphonic acid may be selected from n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-dodecylphosphonic acid, n-tetradecylphosphonic acidIt can be selected from n-hexadecylphosphonic acid and n-octadecylphosphonic acid.

[0116] The above organic alkyl ligand is a ligand having an alkyl-Y structure, and the alkyl portion is C n H 2n+1 It is expressed as such. In the above alkyl-Y, Y can be modified into a structure including functional groups such as an acyl group (RC=O), an alcohol group (-OH), and an amine group (-NH2). For example, the alkyl-Y structure is an acyl group (RC=O, R=C n H 2n+1 ); alkyl alcohols including primary, secondary, and tertiary alcohols (C n H 2n+1 OH); hexadecylamine, 9-octadecenylamine, 1-amino-9-octadecene(1-amino-9-octadecene)(C 19 H 37 It is selected from the group consisting of alkylamines (alkyl-N) containing N; p-substituted aniline, phenylammonium, and fluorinated ammonium. Additionally, the alkyl halide ligand is a ligand of the structure alkyl-X, wherein alkyl can be modified to alkylammonium and X can be Cl, Br, or I as the halide element. For example, an alkylammonium halide ligand may be used.

[0117] In the present invention, the surfactant surrounds the perovskite nanocrystalline particles and acts as a ligand. The ligand is a general term for an ion or molecule that can be bonded to a central atom in a dative complex. In the present invention, the ligand binds to the surface of the nanoparticle and plays a role in precisely controlling the shape and size of the nanoparticle. For a description of such ligands, refer to the paper [Journal of the American Chemistry Society, 2013, 135, 49, pp 18536-18548]. Depending on the mode of binding to the surface of the nanoparticle, the ligand that binds to the surface of the nanoparticle may correspond to an L-type ligand, an X-type ligand, or a Z-type ligand. L-type ligands form dative bonding by donating two electrons, X-type ligands form covalent bonding by donating one electron to a cation site on the surface of a nanoparticle, and Z-type ligands are the acceptors of the two electrons on the surface of the nanoparticle.

[0118] Meanwhile, surfactants are amphiphatic substances that simultaneously possess two opposing functional groups—hydrophilic and hydrophobic—within the same molecule. They can adsorb at the interfaces between liquids and gases, liquids and liquids, or liquids and solids, thereby causing various physical phenomena. Surfactants can play roles such as lowering surface tension, emulsifying, improving wettability and foamability, or solubilizing. In particular, surfactants can enhance the dispersibility of nanoparticles when they bind to the surface through coordination bonding and act as ligands.

[0119] In one embodiment of the present invention, specific examples of the surfactant include butylamine (C4H9NH2) and pentylamine (C5H 11 NH2), Hexylamine (C6H 13 NH2), heptylamine (C7H 15 NH2), Octylamine (C8H 17 NH2), Nonylamine (C9H 19 NH2), Decylamine (Decylamine, C 10 H 21 NH2), oleylamine (oleylamine, C 18 H 35 NH2), oleic acid, 4,4'-Azobis(4-cyanovaleric acid), acetic acid, 5-aminosalicylic acid, acrylic acid, L-aspartic acid, 6-bromohexanoic acid, bromoacetic acid, dichloroacetic acid, ethylenediaminetetraacetic acid, isobutyric acid, itaconic acid, maleic acid, r-maleimidobutyric acid, L-malic acid, It may be one or more selected from 4-nitrobenzoic acid and 1-pyrenecarboxylic acid, but is not limited thereto.

[0120] In addition, as anionic surfactants, sulfates such as ammonium lauryl sulfate, sodium lauryl sulfate, sodium dodecyl sulfate, sodium laureth sulfate, and sodium myreth sulfate; sulfons such as dioctyl sodium sulfosuccinate, perfluorooctanesulfonate, perfluorobutanesulfonate, and linear alkylbenzene sulfates; phosphate esters, such as sodium stearate and sodium lauroylsarcosinate. Carboxylates including perfluorononanoates and perfluorooctanoates, cationic surfactants (including primary, secondary, tertiary, and quaternary ammonium cations) and quaternary ammonium cations such as benzalkonium chloride, dimethyldioctadecylammonium chloride, trimethylglycine, and choline, zwitterionic or amphoteric surfactants having both cations and anions in the same substance, and nonionic surfactants such as fatty alcohols cetyl alcohol, stearyl alcohol, cetostearyl alcohol (mainly including cetyl alcohol and stearyl alcohol), and long-chain alcohols such as oleyl alcohol. but,It is not limited to this.

[0121] In the present invention, the alkyl halide may have an alkyl-X structure. In this case, the halogen element corresponding to X may include Cl, Br, or I, etc. Additionally, the alkyl structure may include C n H 2n+1 Acyclic alkyl having the structure, C n H 2n+1 Primary alcohols having structures such as OH, secondary alcohols, and tertiary alcohols, and alkylamines having an alkyl-N structure (e.g., Hexadecyl amine, 9-octadecenylamine, 1-Amino-9-octadecene(C1)). 19 H 37 It may include, but is not limited to, p-substituted aniline, phenyl ammonium, or fluoroammonium.

[0122] The amine ligand may be selected from N,N-diisopropylethylethylamine, ethylenediamine, hexamethylenediamine, methylamine, hexylamine, oleylamine, N,N,N,N-tetramethylethylenediamine, triethylamine, diethanolamine, and 2,2-(ethylenedioxyl)bis-(ethylamine) (2,2-(ethylenedioxyl)bis-(ethylamine)).

[0123] The above alkyl ammonium halide includes methylammonium chloride, dimethylammonium bromide, and octylammonium bromide, and in some cases, may be replaced with other forms of salts other than halides, such as fluorides or acetates like ethyl dimethylammonium fluoride and tetrabenzylammonium acetate, but is not limited thereto.

[0124] The above carboxylic acid is 4,4'-Azobis(4-cyanovaleric acid)), acetic acid, 5-aminesalicylic acid, acrylyl acid, L-aspartic acid, 6-bromohexanoic acid, promoacetic acid, dichloroacetic acid, ethylenediaminetetraacetic acid, isobutyric acid, itaconic acid, maleic acid, r-maleimidobutyric acid, It may include L-Malic acid, 4-Nitrobenzoic acid, 1-Pyrenecarboxylic acid, or oleic acid.

[0125] The above phosphonic acid may be selected from n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-dodecylphosphonic acid, n-tetradecylphosphonic acid, n-hexadecylphosphonic acid, and n-octadecylphosphonic acid, but is not limited thereto.

[0126] The above organic ligand may be in a fluorinated form. For example, the above organic ligands are 2-fluorophenylboronic acid, 3,5-diformyl-2-fluorophenylboronic acid, 3-chloro-4-fluorophenylboronic acid, 4-cyano-3-fluorobenzoic acid, L-Fmoc-3-fluorophenylalanine, L-Fmoc-4-fluorophenylalanine, methyl-6-fluorochromone-2-carboxylic acid, 4-fluorobenzoic acid, 2-fluorobenzoic acid, 2-fluorobenzylamine, 2-fluorocinnamic acid, 2-fluorophenyl isothiocyanate, 4-fluorobenzenesulfonic acid, 4-fluorobenzylamine, 4-fluorophenyl isothiocyanate, 4-fluorophenylacetic acid, Fluorocinnamic acid, (3-fluoro-4-methylphenyl)acetic acid, (3-fluoro-5-isopropoxyphenyl)boronic acid,(3-fluoro-5-methoxycarbonylphenyl)boronic acid, (3-fluoro-5-methylphenyl)boronic acid, (4-fluoro-2-methoxyphenyl)oxoacetic acid, (4-fluoro-3-methoxyphenyl)acetic acid, (4-fluoro-3-methoxyphenyl)boronic acid, and combinations thereof, but are not limited thereto.

[0127] Additionally, preferably, the fluorinated organic compound may be in the form of a perfluorinated compound. The perfluorinated compound may be, but is not limited to, perfluorinated alkyl halides, perfluorinated aryl halides, fluorochloroalkenes, perfluoroalcohols, perfluorinated amines, perfluorocarboxylic acids, perfluorosulfonic acids, or derivatives thereof.

[0128] The above perfluorinated alkyl halides and perfluorinated aryl halides may be trifluoroiodomethane, pentafluoroethyl iodide, perfluorooctyl bromide (perflubron), dichlorodifluoromethane, and derivatives thereof, but are not limited thereto.

[0129] The above fluorochloroalkene may be chlorotrifluoroethylene, dichlorodifluoroethylene, and derivatives thereof, but is not limited thereto.

[0130] The above fluorochloroalkene may be chlorotrifluoroethylene, dichlorodifluoroethylene, and derivatives thereof, but is not limited thereto.

[0131] The above perfluorocarboxylic acid may be trifluoroacetic acid, heptafluorobutyric acid, pentafluorobenzoic acid, perfluorooctanoic acid, perfluorononanoic acid, and derivatives thereof, but is not limited thereto.

[0132] The above perfluorosulfonic acid may be triflic acid, perfluorobutanesulfonic acid, perfluorobutanesulfonamide, perfluorooctanesulfonic acid, and derivatives thereof, but is not limited thereto.

[0133] The above ligands may be triocrylphosphine oxide (TOPO), trioctylphosphine (TOP), triethylphosphine oxide, tributylphosphine oxide, and derivatives thereof, but are not limited thereto.

[0134] As described above, the alkyl halide used as a surfactant to stabilize the surface of the precipitated metal halide perovskite becomes an organic ligand surrounding the surface of the halide metal halide perovskite nanocrystal. Meanwhile, if the length of the alkyl halide surfactant is short, the size of the formed nanocrystal becomes large, so it can be formed to be 100 nm or more, further 300 nm or more, or even exceed 1 μm. In this case, a fundamental problem may arise in which excitons cannot proceed to luminescence due to thermal ionization and delocalization of charge carriers within the large nanocrystal and are separated into free charges and annihilated. Therefore, by using an alkyl halide of a certain length or longer as a surfactant, the size of the halide metal halide perovskite nanocrystal formed can be controlled to a certain size or smaller (i.e., 100 nm or less, preferably 30 nm or less).

[0135] In addition, as the size of conventionally used inorganic quantum dots decreases to below the exciton Bohr diameter, there are disadvantages such as difficulty in controlling the size of the quantum dots, color purity and spectrum being affected by the size and size distribution, and efficiency actually decreasing due to defects on the nanocrystal surface. To solve this, it is possible to provide nanocrystal particles that have a size larger than the Bohr diameter, are not affected by quantum confinement effects, and produce maximum luminescence efficiency.

[0136] Methods for deriving the exciton bore diameter may be referenced in the paper [ACS Nano, 2017, 11(7), pp 6586-6593, AIP Advances, 2018, 8, 025108] and supporting information, as well as the references cited in the said paper, in particular [Nature Physics, 2015, 11, 582; Energy & Environmental Science, 2016, 9, 962; J. Phys. Chem. Lett., 2017, 8, 1851]. In one embodiment, for MAPbBr3, the exciton bore diameter may be approximately 10 nm. Depending on the material, this may be smaller or higher than 10 nm. The parameters used for these measurements can be determined within the range that can be considered by those skilled in the art to which the present invention pertains. According to recent papers on the dielectric constant as a function of frequency [Advanced Energy Materials, 2017, 7, 1700600; APL Materials, 2019, 7, 010901; Advanced Materials, 2019, 31, 1806671], the dielectric constant (ε r ) must not use values ​​in the dynamic dielectric constant range higher than high frequencies (>1,000,000 Hz), and 10 6 It must be determined by considering the static dielectric constant (ε0) below Hz. High frequencies (approx. 10 15 It is the region where an optical response occurs at Hz, and in this region ε ∞ It can be defined. The dielectric constant used to calculate the exciton Bohr diameter is ε ∞Values ​​between and ε0 must be used. Considering that organic semiconductor materials typically have a dielectric constant of 3 to 5, the static dielectric constant of ionic halide metal halide perovskite materials must be derived to be significantly larger than this value. The dielectric constant of the ionic halide metal halide perovskite material has a value of 10 to 50 when measured at room temperature, and more preferably 20 to 35 at room temperature. While it may vary with temperature, it typically exhibits a value of 20 to 100 with changes in temperature. CsPbBr3 materials have a dielectric constant that is almost independent of temperature, whereas organic-inorganic hybrid metal halide perovskites exhibit a dependence on temperature. Furthermore, measurements must be taken using a pure metal halide perovskite thin film without ligands, and the value measured at room temperature must be substituted into the formula. In typical metal halide perovskite semiconductors in the range of 1 eV to 3.5 eV, it is reasonable for the dielectric constant of the metal halide perovskite to be at least twice as large as that of the organic material. The above dielectric constant can be measured using a conventional LCR meter or obtained by fitting an equivalent circuit after measuring with impedance spectroscopy equipment. Furthermore, as disclosed in the papers [Nature Physics, 2015, 11, 582; Energy & Environmental Science, 2016, 9, 962; J. Phys. Chem. Lett., 2017, 8, 1851], after calculating the effective mass and exciton binding energy, Equation R * =R0μ / m0ε 2 r(here, R * =exciton binding energy, R0=atomic Rydberg constant, m0=free electron mass, μ=reduced effective mass defined by 1 / μ=1 / μh +1 / μ e , m h =effective mass of hole, m e It can be calculated using the effective mass of electron. Calculated in this way, the effective dielectric constant reported in the paper [AIP Advances, 2018, 8, 025108] is 11.4. In this case, the value μ=0.117m0 is used. The calculated exciton Bohr radius is 5.16 nm and the exciton Bohr diameter is 10.32 nm.

[0137] The exciton Bohr diameter can be obtained by the value for the effective mass of the metal halide perovskite and the above equation (2).

[0138] In addition, a device with an ITO / PEDOT:PSS / perovskite film / electron injection layer / cathode structure is fabricated, and the capacitance (C) value of the perovskite thin film at 1000 Hz is measured using impedance spectroscopy. Subsequently, the equation C = ε r Through ε0A / d, where A is the device area and d is the thickness, ε r The exciton bore diameter was calculated to be 12.4 nm using the reduced effective mass value (μ=0.117 m0) from the paper [Energy & Environmental Science, 2016, 9, 962] for MAPbBr3.

[0139] At this time, the dielectric constant must be measured at room temperature using a pure metal halide perovskite thin film without ligands. While it may vary depending on the material, it generally has a value of 7 to 30, and more preferably, a value of 7 to 20; if a value smaller than 7 is obtained, it is possible that it is due to measurement error. In the case of MAPbBr3, it appears that it may vary depending on the crystal size or the quality of the thin film, but a value between 7 and 20 is a desirable range. Furthermore, if different values ​​are obtained depending on the quality of the thin film, the measurement value obtained using the thin film prepared when the grain size is configured to be the largest should be followed.

[0140] Another method for experimentally determining the exciton Bohr diameter is to consider that the point at which the photoluminescence peak wavelength begins to change abruptly with nanoparticle size is very close to the exciton Bohr diameter. Alternatively, it can be regarded as the particle size at the point where the Full Width at Half Maximum (FWHM) of the photoluminescence spectrum begins to increase. Quantum confinement effects begin below the aforementioned exciton Bohr diameter, and particles below this point are referred to as quantum dots. If particle size becomes progressively smaller in the quantum dot region and uniformity of particle size exists, the photoluminescence peak shifts toward the blue direction as the size decreases. Since the color changes with size variation, the FWHM increases when the photoluminescence spectra of all particles are aggregated. It is preferable to measure particle size using a Transmission Electron Microscope (TEM). Measurements made using light scattering methods can lead to significant errors in particle size. When particles are clustered, it is difficult to analyze the size of a single particle, and the size of the clustered particles may be overestimated.

[0141] This quantum confinement effect refers to a phenomenon observed when energy bands are influenced by changes in the atomic structure of particles, and the exciton Bohr diameter refers to the point (size of the semiconductor particle) where the quantum confinement effect occurs. In other words, in the case of a quantum dot where the semiconductor particle size is less than or equal to the exciton Bohr diameter, the quantum confinement effect occurs as the particle size decreases, and consequently, the "band gap" and the corresponding "photoluminescence (PL) spectrum" change. Therefore, in order to determine the actual value of the exciton Bohr diameter, it is necessary to find the region where the quantum confinement effect begins, that is, the point where the photoluminescence spectrum changes according to the size of the semiconductor particle.

[0142] However, even when the particle size is larger than the exciton Bohr diameter, changes occur in the electron-hole interaction within the semiconductor, which can alter the bandgap and emission wavelength of the semiconductor particle. However, since the amount of change in this region is very small, it is commonly referred to as the "weak confinement regime." On the other hand, the quantum confinement regime, where the bandgap changes significantly depending on the size of the quantum dot particle, is referred to as the "strong confinement regime." Therefore, to determine the exciton Bohr diameter, the boundary between the weak confinement regime and the strong confinement regime must be identified. When the particle size obtained experimentally through the point where the PL peak or FWHM changes abruptly (the point where the tangent line drawn along the slopes intersects when there are two abruptly different slopes) matches the value calculated using the above mathematical formula within a small margin of error (about 10%), the obtained exciton Bohr diameter can be considered a physically meaningful value.

[0143]

[0144] According to one embodiment of the present invention, a first solution and a second solution can be formed respectively using the surfactant and the solvent, and then mixed to form the perovskite nanocrystal core. In the present invention, the surface of the perovskite nanocrystal core may be formed in a form surrounded by organic ligands. The core can be purified and dispersed in a solvent to perform the following process.

[0145] Next, the perovskite nanocrystal core of S20 and the first inorganic shell precursor can be reacted to form a core-first inorganic shell structure in which the first inorganic shell is arranged to surround the perovskite nanocrystal core.

[0146]

[0147] <Preparation Example 1: Preparation of Perovskite Nanocrystals with Hierarchical Core-Shell-Shell-Shell Structure>

[0148] 0.6 g of PbBr2 and 3.75 mL of oleic acid (OA) and oleylamine (OLA) are dispersed in 35 mL of 1-octene. The dispersion solution is vacuum dried at 120°C for 60 minutes, and then 6 mL of 0.125 M Cs-oleate precursor is injected at 180°C to form CsPbBr3 perovskite nanocrystals (PeNCs). After cooling and purification, CsPbBr3PeNC cores stabilized with oleic acid and oleylamine can be obtained. Subsequently, the CsPbBr3PeNC cores are treated with (APTES)2SO4 as shown in Fig. 6 to obtain APTES-stabilized CsPbBr3 / PbSO4 core-shell structured PeNCs. A double-shell CsPbBr3 / PbSO4 / SiO2PeNC is formed by additionally coating with SiO2 through the slow hydrolysis of TMOS / TEOS. Subsequently, the CsPbBr3 / PbSO4 / SiO2PeNC is mixed with siloxane precursors DPSD (diphenylsilanediol) and MPTMS (3-methacryloxypropyltrimethoxysilane) to grow a siloxane polymer shell and simultaneously form a perovskite nanocrystal / siloxane hybrid resin with a hierarchical shell structure. The method for preparing the siloxane polymer resin is characterized by carrying out a condensation reaction in the presence of a Ba(OH)2 catalyst.

[0149] Figure 7 illustrates the band gaps of CsPbBr3, PbSO4, SiO2, and siloxane. Since PbSO4 has a much wider band gap than CsPbBr3, it can trap excitons in the CsPbBr3 core and heal surface defects. The band gaps of the second inorganic SiO2 shell and the siloxane organic ligand shell are 8.9 eV and 3.4 eV, respectively, and they do not absorb visible light.

[0150] FIG. 8 is a schematic diagram illustrating a perovskite nanocrystal stabilized by a hierarchical shell interfacial structure according to an embodiment of the present invention. As shown in FIG. 8, the structure of the hierarchical shell CsPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystal is such that each layer is connected through coordination bonds, covalent bonds, or ionic bonds. This connection structure contributes to the stability of the overall core-shell-shell-shell structure and, at the same time, helps improve surface passivation of the perovskite nanocrystal, thereby contributing to the enhancement of luminescence quantum efficiency. CsPbBr3 and PbSO4 are connected by Pb-SO4 ionic bonds, PbSO4 and SiO2 are connected by APTES, and APTES and PbSO4 are connected by NH 3+ and SO4 2- They are connected by ionic bonds, and SiO2 and APTES are connected by Si-O covalent bonds. SiO2 and siloxane are connected by Si-O covalent bonds. These interconnected structures are useful for anchoring and stabilizing the perovskite lattice.

[0151] FIG. 9 is a graph showing the photoluminescence spectra of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention. Referring to FIG. 9, the PL characteristics of a perovskite nanocrystal having a hierarchical shell structure according to the present invention are illustrated.

[0152] Table 1 below shows the measured optical properties of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention.

[0153]

[0154] Referring to Figure 9 and Table 1, the PLQY of the APTES-stabilized CsPbBr3 / PbSO4 core-shell-shell-shell perovskite nanocrystals increased from 46% to over 99% after treatment with (APTES)2SO4, which indicates that the PbSO4 shell layer effectively protects against surface defects.

[0155] In addition, perovskite nanocrystals still maintain over 99% PLQY even after the SiO2 shell is grown. PLQY drops slightly to 94% after the siloxane ligand shell is grown.

[0156] FIG. 10 is a TEM image analyzing the morphological change during the formation of a hierarchical shell-structured perovskite nanocrystal according to one embodiment of the present invention. The core of the CsPbBr3 perovskite nanocrystal is cubic with an average size of 8.8 nm. Referring to FIG. 10, the average size of the perovskite nanocrystal with a CsPbBr3 / PbSO4 core-shell-shell-shell structure increases slightly to 9.0 nm. Additionally, the edge structure of the double-shell CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal (average size: 9.3 nm) is blurred, indicating that an amorphous SiO2 shell was successfully formed.

[0157] Figure 11 is a High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) image of a hierarchical shell CsPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystal according to one embodiment of the present invention. Referring to Figure 11, it can be seen that the core-shell PeNC is covered with an amorphous siloxane polymer matrix.

[0158] FIG. 12 is a graph illustrating the analysis by X-ray Photoelectron Spectroscopy (XPS) of a core-shell-shell-shell structured perovskite nanocrystal according to one embodiment of the present invention. FIG. 13 is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of (a) a CsPbBr3 core and (b) a CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal according to one embodiment of the present invention. FIG. 14 is a STEM-EDS mapping image of a CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal according to one embodiment of the present invention. The ratios of the elements described in FIG. 12 are summarized in Table 2 below.

[0159]

[0160] Figures 12 through 14 and Table 2 illustrate the characteristics for identifying PbSO4 shells and SiO2 shells. Compared to the CsPbBr3 core, the surface Cs and Br elements of the core-shell-shell-shell perovskite nanocrystals decrease, while the surface Pb and S atoms increase, indicating the formation of a PbSO4 shell. In the CsPbBr3 core, the surface Cs / Pb ratio is 1.04, indicating that both Cs and Pb atoms are dominant on the surface. However, in the core-shell sample, the Cs / P ratio decreases to 0.85, indicating that Pb atoms are dominant at the ends. Monitoring the ends of the CsPbBr3 core and core-shell samples using HAADF-STEM, as shown in Figure 13, reveals that Cs and Pb atoms are present at the ends of the CsPbBr3 core, while Pb atoms are dominant in the core-shell sample. This is consistent with the XPS results and indicates that PbSO4 shells were formed. Referring to Fig. 14, the elements Cs, Pb, Br, S, Si, and O are uniformly dispersed in the core-shell-shell-shell structured perovskite nanocrystals, which indicates that PbSO4 and SiO2 shells were well formed.

[0161] FIG. 15 shows (a) an optical image and (b) a fluorescence image of a CsPbBr3 / siloxane resin and a hierarchical shell HS-CsPbBr3 / siloxane according to one embodiment of the present invention. Referring to FIG. 15, the CsPbBr3 core can be mixed and dispersed in the siloxane, but phase separation occurs after 4 days of storage and complete phase separation occurs after 23 days of storage, and HS-CsPbBr3 can be mixed with the siloxane to form a uniform resin solution due to the presence of siloxane ligands. Therefore, it remains evenly dispersed in the siloxane even after storage for 165 days. This indicates that the external siloxane ligands assist in the dispersion of the perovskite nanocrystals in the siloxane resin, demonstrating excellent compatibility between the HS-CsPbBr3 perovskite nanocrystals and the siloxane resin. In addition, the HS-perovskite nanocrystalline siloxane resin has excellent storage stability and can be stored for more than 450 days in a refrigerator at 8 to 10°C. Therefore, referring to FIG. 15(b), the film made of the siloxane resin exhibits very similar PLQY depending on the storage time.

[0162] In one embodiment of the present invention, viscosity and resin molecular weight tests were performed to further define the interaction between siloxane and CsPbBr3 / PbSO4 / SiO2 core-shell quantum dots. FIG. 16(a) is a graph showing the interrelationship between viscosity and shear rate for pure siloxane, CsPbBr3 / siloxane, and HS-CsPbBr3 / siloxane according to one embodiment of the present invention, and FIG. 16(b) is a graph showing the results of molecular weight tests by gel permeation chromatography (GPC) according to one embodiment of the present invention. As shown in FIG. 16(a), the pure siloxane resin and the CsPbBr3 / siloxane resin exhibit similar viscosities at different shear rates, and the viscosity of HS-CsPbBr3 / siloxane is much higher. This indicates that there is a strong interaction between HS-CsPbBr3 and siloxane.

[0163] The molecular weights of pure siloxane, CsPbBr3 / siloxane, and HS-CsPbBr3 / siloxane according to one embodiment of the present invention are listed in Table 3 below.

[0164]

[0165] Referring to Figure 16 and Table 3, it can be seen from the GPC results that HS-CsPbBr3 / siloxane has a higher average molecular weight (Mn), which is consistent with the viscosity test results, and further indicates that siloxane can increase molecular weight and viscosity by combining with CsPbBr3 / PbSO4 / SiO2.

[0166] FIG. 17(a) is a Si-29 nuclear magnetic resonance (NMR) graph of CsPbBr3 / siloxane and HS-CsPbBr3 / siloxane according to one embodiment of the present invention, and FIG. 17(b) is a chemical formula of a silicon atom. Referring to FIG. 17, Si-29 nmR analysis was performed, and as shown in FIG. 17(b), D n and T n represents the Si of DPSD and MPTS, respectively. D of HS-CsPbBr3 / siloxane compared to the CsPbBr3 / siloxane sample 1 and D 2 It can be seen that Si exhibits a similar signal. However, T 1 While the Si signal decreases significantly, T 2 Wow T 3 The signal of Si is significantly enhanced. This indicates that the silicon matrix becomes denser and more condensed because HS-perovskite nanocrystals in the HS-CsPbBr3 / siloxane sample can act as crosslinking sites for the siloxane polymer. In other words, HS-CsPbBr3 and siloxane form a denser silicon matrix network, which is advantageous for improving the stability of quantum dots.

[0167] FIG. 18 illustrates the fluorescence spectrum of a perovskite nanocrystal / siloxane hybrid film according to one embodiment of the present invention. FIG. 18(a) is the fluorescence spectrum of a film prepared by mixing perovskite nanocrystals with a siloxane resin. In the present invention, the method for preparing a siloxane polymer resin is characterized by introducing a photoinitiator into the siloxane resin. The above photoinitiators are benzoin methyl ether (BDK), benzoin ethyl ether (BEE), benzoin sobutyl ether (BIB), benzoin toluene sulfonate (BTS), camphorquinone (CQ), Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone), Irgacure 184 (1-hydroxycyclohexylphenyl ketone), Irgacure 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one), Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), Lucirin TPO (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide), 1-hydroxycyclohexylphenyl ketone (irgacure 819), and isopropylthioxantone (ITX). It may include one or more selected from among.

[0168] The PLQY of the CsPbBr3 core-based film is only 32%, and the fluorescence peak shifts to 520 nm due to the aggregation of CsPbBr3 perovskite nanocrystals. However, perovskite nanocrystals with a hierarchical shell structure can effectively protect the perovskite nanocrystals from degradation during the film preparation process. Referring to Fig. 18(b), it can be seen that the HS-CsPbBr3 perovskite nanocrystal-based film exhibits a bright green color under UV light, with a PLQY of 84% and a fluorescence peak maintained at 518 nm.

[0169] FIG. 19 is a graph showing the results of an aging stability test of CsPbBr3 / siloxane, CsPbBr3 / PbSO4 / siloxane, and CsPbBr3 / PbSO4 / APTES perovskite nanocrystalline films according to an embodiment of the present invention, where FIG. 19(a) shows the humid heat stability at 60°C and 90% RH, and FIG. 19(b) shows the stability under blue light (23 mW / cm²). 2 It exhibits photostability when irradiated.

[0170] FIG. 20 is a graph showing the aging stability of a hierarchical shell-stabilized HS-CsPbBr3 / PeNC / siloxane hybrid film according to an embodiment of the present invention, where FIG. 20(a) shows the moist heat aging PLQY at 60°C and less than 90% RH, FIG. 20(b) shows the spectral stability, and FIG. 20(c) shows the blue light (23 mW / cm²). 2 PLQY and FIG. 20(d) under irradiation are blue light (23 mW / cm²) 2 It exhibits spectral stability under investigation.

[0171] The film lifetime according to Fig. 20 is summarized in Table 4 below. At 60°C and 90% RH, the CsPbBr3 / siloxane film is T 90 The lifetime (time taken to reach 90% of maximum intensity) is only 13 hours, and the T of CsPbBr3 / PbSO4 and CsPbBr3 / PbSO4 / APTES core-shell-shell-shell structured perovskite nanocrystalline films 90 It can be seen that the lifespan has improved to 88 hours and 68 hours.

[0172]

[0173] T of HS-CsPbBr3 90 The lifespan reached 3,211 hours during aging at 60°C and 90% RH, which is the commercial standard (T 90 The lifespan exceeds 1,000 hours. 23 mW / cm² 2 Regarding photostability of less than T, the CsPbBr3 / siloxane film is T 90While the lifetime is only 19 hours, the T of CsPbBr3 / PbSO4 and CsPbBr3 / PbSO4 / APTES core-shell perovskite nanocrystalline films 90 Lifespan was improved to 99 and 951 hours. T of HS-CsPbBr3 film 90 The lifespan is 23 mW / cm² 2 The investigation period is over 10,000 hours. As shown in Figs. 20(b) and 20(d), the PL spectrum of the HS-CsPbBr3 film maintains the same PL peak and FWHM under both aging conditions. The excellent stability of the HS-CsPbBr3 film indicates a good synergistic effect of the hierarchical core-shell-shell-shell structure.

[0174] <Preparation Example 2: Preparation of a film containing perovskite nanocrystalline particles of a hierarchical core-shell-shell-shell structure>

[0175] The procedure for preparing an HS-MAPbBr3 perovskite nanocrystalline film according to one embodiment of the present invention is as follows: 1) 10 mL of toluene, 4 mL of 1-butanol, 0.6 mL of oleic acid, and 48.4 μl of n-decylamine are mixed to prepare a MAPbBr3 core. 2) Subsequently, 0.3 mL of a MAPbBr3 precursor is injected at room temperature. To prepare the MAPbBr3 precursor, 44.8 mg of MABr and 273 mg of PbBr are dispersed in 1 mL of DMF. 3) After purifying the prepared mixture, a MAPbBr3 perovskite nanocrystalline core stabilized with oleic acid and n-decylamine is obtained. 4) Subsequently, the MAPbBr3 perovskite nanocrystal core is treated with (APTES)2SO4 to obtain APTES-stabilized MAPbBr3 / PbSO4 core-shell structured perovskite nanocrystals. The perovskite nanocrystals are further coated with SiO2 via slow hydrolysis of TMOS / TEOS to form hierarchical shell structured MAPbBr3 / PbSO4 / SiO2 perovskite nanocrystals. 5) To prepare a MAPbBr3 / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) are condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-MAPbBr3 / siloxane film with 99% PLQY and an emission peak of 529 nm is manufactured.

[0176] Typically, mixed halide perovskite nanocrystals are prepared to obtain blue and red emitters for the application of perovskite nanocrystals in full-color displays. However, mixed halide perovskite nanocrystals have limitations in their application to displays due to photo-induced phase separation and color changes. The HS-MAPbBr3 / siloxane film prepared according to Preparation Example 2 of the present invention [shows] at 60°C and 90% RH or blue light (23 mW / cm² 2 More than 2000 hours of T in ) 90 It has excellent aging stability over its lifespan.

[0177] FIG. 21 is a graph showing the stability over time of a hierarchical shell for stabilizing a MAPbBr3PeNC / siloxane hybrid film according to an embodiment of the present invention, where FIG. 21(a) is at 60°C and 90% RH and FIG. 21(b) is under blue light (23 mW / cm²). 2 It shows aging stability. Referring to Fig. 21, it can be seen that a hierarchical shell structure can be applied to fabricate a bright and stable pure green MAPbBr3 / PbSO4 / SiO2 / siloxane perovskite nanocrystalline film.

[0178] <Preparation Example 3: Preparation of a film containing perovskite nanocrystalline particles of a hierarchical core-shell-shell-shell structure>

[0179] HS-CsPbCl according to one embodiment of the present invention 1.4 Br 1.6 The procedure for preparing the perovskite nanocrystalline film is as follows: 1) CsPbCl 1.4 Br 1.6 For core preparation, 0.413 g of PbBr2 and 0.293 g of PbCl2 are dispersed in a mixed solution of 5 mL of oleic acid (OA), 5 mL of oleylamine (OLA), and 40 mL of 1-octene. 2) After vacuum drying the prepared solution at 120°C for 60 minutes, 5 mL of 0.125 M Cs-oleate precursor is injected at 200°C to form CsPbCl1.4 Br 1.6 PeNCs form perovskite nanocrystals. 3) After cooling and purifying the prepared solution, CsPbCl stabilized with oleic acid and oleylamine 1.4 Br 1.6 A perovskite nanocrystal core is obtained. 4) Subsequently, CsPbCl is prepared using (APTES)2SO4. 1.4 Br 1.6 APTES-stabilized CsPbCl by treating perovskite nanocrystalline cores 1.4 Br 1.6 Perovskite nanocrystals with a PbSO4 core-shell structure are obtained. The prepared perovskite nanocrystals are further coated with SiO2 via slow hydrolysis of TMOS / TEOS to form CsPbCl2 with a hierarchical shell structure. 1.4 Br 1.6 Forms / PbSO4 / SiO2 perovskite nanocrystals. 5) CsPbCl 1.4 Br 1.6 To prepare a / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) are condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-CsPbCl resin with a PLQY of 41% and an emission peak of 460 nm is prepared. 1.4 Br 1.6 A siloxane film was obtained. In addition, HS-CsPbCl 1.4 Br 1.6 / Siloxane film is CsPbCl 1.4 Br 1.6 / T of siloxane film 90 Compared to a lifespan of 3 hours, blue light (23mW / cm²) 2 More than 1000 hours of T under ) 90 It exhibits improved photostability over the lifetime. As shown in FIGS. 22(b) and 22(c), CsPbCl 1.4 Br 1.6 / While the PL peak of the siloxane film was blue-shifted under light irradiation, HS-CsPbCl 1.4 Br1.6 The PL peak of the siloxane film remains the same. All these results indicate that the hierarchical shell can stabilize the lattice of mixed halide perovskite nanocrystals and suppress phase separation.

[0180] FIG. 22(a) shows blue light (23 mW / cm²) according to one embodiment of the present invention. 2 Blue CsPbCl stabilized under irradiation 1.4 Br 1.6 This is a graph showing the photostability of the hierarchical shell of the PeNC / siloxane film, and FIGS. 22(b) and FIGS. 22(c) are CsPbCl 1.4 Br 1.6 / Siloxane film and HS-CsPbCl 1.4 Br 1.6 This is a graph showing the spectral stability corresponding to each siloxane film. Referring to Fig. 22, the bright and stable deep blue mixed halide CsPbCl 1.4 Br 1.6 This demonstrates that a hierarchical shell structure can be applied to fabricate / PbSO4 / SiO2 / siloxane PeNC films.

[0181] <Preparation Example 4: Preparation of a film containing perovskite nanocrystalline particles with a hierarchical core-shell-shell-shell structure>

[0182] HS-CsPbI 1.8 Br 1.2 The procedure for preparing perovskite nanocrystalline films is as follows: 1) CsPbI 1.8 Br 1.2 For core preparation, 20.32 g of PbBr and 20.6 g of PbI are dispersed in a mixed solution of 5 mL of oleic acid (OA), 5 mL of oleylamine (OLA), and 40 mL of 1-octene. 2) The prepared solution is vacuum dried at 120°C for 60 minutes, and then 5 mL of 0.125 M Cs-oleate precursor is injected at 180°C to form CsPbI 1.8 Br 1.2Forms perovskite nanocrystals. 3) After cooling and purifying the prepared solution, CsPbI₂ stabilized with oleic acid and oleylamine 1.8 Br 1.2 A perovskite nanocrystal core is obtained. 4) Subsequently, CsPbI is prepared using (APTES)2SO4. 1.8 Br 1.2 APTES-stabilized CsPbI by treating perovskite nanocrystal cores 1.8 Br 1.2 Perovskite nanocrystals with a PbSO4 core-shell structure are obtained. The prepared perovskite nanocrystals are further coated with SiO2 via slow hydrolysis of TMOS / TEOS to form CsPbI4 with a hierarchical shell structure. 1.8 Br 1.2 Forms / PbSO4 / SiO2 perovskite nanocrystals. 5) CsPbI 1.8 Br 1.2 To prepare a / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) are condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, HS-CsPbI with a PLQY of 81% and an emission peak of 627 nm is prepared. 1.8 Br 1.2 A siloxane film was obtained. Also, HS-HS-CsPbI 1.8 Br 1.2 / Siloxane film is blue light (23 mW / cm²) 2 More than 2000 hours of T under ) 90 It exhibits excellent photostability over its lifespan.

[0183] FIG. 23 is a red CsPbI according to an embodiment of the present invention 1.8 Br 1.2 A graph plotting the time-dependent stability (PL peak: 627 nm) of a hierarchical shell for stabilizing perovskite nanocrystals, where Fig. 23(a) shows PLQY and Fig. 23(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2It represents HS-CsPbI as shown in Fig. 23(b). 1.8 Br 1.2 The PL peak of the siloxane film remains the same even under blue light irradiation. These results indicate that the hierarchical shell can stabilize the lattice of the mixed halide perovskite nanocrystals and suppress phase separation. In conclusion, referring to Fig. 23, the bright and stable pure red mixed halide CsPbI 1.8 Br 1.2 This shows that a hierarchical shell structure can be applied to fabricate / PbSO4 / SiO2 / siloxane perovskite nanocrystalline films.

[0184] <Preparation Example 5: Preparation of a film containing perovskite nanocrystalline particles with a hierarchical core-shell-shell-shell structure>

[0185] The procedure for preparing HS-CsPbI2Br perovskite nanocrystalline films is as follows: 1) To prepare a CsPbI2Br core, 0.26g of PbBr2 and 0.67g of PbI2 are dispersed in a mixed solution of 5mL of oleic acid (OA), 5mL of oleylamine (OLA), and 40mL of 1-octene. 2) The prepared solution is vacuum dried at 120°C for 60 minutes, and then 5mL of 0.125 M Cs-oleate precursor is injected at 180°C to form CsPbI2Br perovskite nanocrystals. 3) After cooling and purification, a CsPbI2Br perovskite nanocrystalline core stabilized with oleic acid and oleylamine is obtained. 4) Next, the CsPbI2Br perovskite nanocrystal core is treated with (APTES)2SO4 to obtain APTES-stabilized CsPbI2Br / PbSO4 core-shell structured perovskite nanocrystals. The prepared perovskite nanocrystals are further coated with SiO2 via slow hydrolysis of TMOS / TEOS to form hierarchical shell structured CsPbI2Br / PbSO4 / SiO2 perovskite nanocrystals. 5) To prepare a CsPbI2Br / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) are condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-CsPbI2Br / siloxane film with a PLQY of 82% and an emission peak of 656 nm was obtained. In addition, the HS-CsPbI2Br / siloxane film emitted blue light (23 mW / cm²). 2 More than 2000 hours of T under ) 90 It exhibits excellent photostability over its lifespan.

[0186] FIG. 24 is a graph showing the time-dependent stability (PL peak: 656 nm) of a hierarchical shell for stabilizing deep red CsPbI2Br perovskite nanocrystals according to an embodiment of the present invention, where FIG. 24(a) shows PLQY and FIG. 24(b) shows the spectral stability (23 mW / cm²) under blue light irradiation.2 ... indicates. As shown in Fig. 24(b), the PL peak of the HS-CsPbI2Br / siloxane film remains the same even under blue light irradiation. These results indicate that the hierarchical shell can stabilize the lattice of the mixed halide perovskite nanocrystals and suppress phase separation. In conclusion, referring to Fig. 24, it is shown that a hierarchical shell structure can be applied to fabricate bright and stable deep red mixed halide CsPbI2Br / PbSO4 / SiO2 / siloxane perovskite nanocrystal films.

[0187] <Preparation Example 6: Preparation of a film containing perovskite nanocrystalline particles of a hierarchical core-shell-shell-shell structure>

[0188] The procedure for preparing HS-CsPbI3 perovskite nanocrystalline films is as follows: 1) For the preparation of the CsPbI3 core, Pb is added to a mixed solution of 5 mL of oleic acid (OA), 5 mL of oleylamine (OLA), and 40 mL of 1-octene. I21.0 g is dispersed. 2) The prepared solution is vacuum dried at 120°C for 60 minutes, and then 5 mL of 0.125 M Cs-oleate precursor is injected at 180°C to form CsPbI2Br perovskite nanocrystals. 3) After cooling and purification, CsPbI3 perovskite nanocrystal cores stabilized with oleic acid and oleylamine are obtained. 4) Subsequently, the CsPbI3 perovskite nanocrystal cores are treated with (APTES)2SO4 to obtain APTES-stabilized CsPbI3 / PbSO4 core-shell structured perovskite nanocrystals. The prepared perovskite nanocrystals are further coated with SiO2 via slow hydrolysis of TMOS / TEOS to form hierarchical shell structured CsPbI3 / PbSO4 / SiO2 perovskite nanocrystals. 5) To prepare a CsPbI3 / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) were condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-CsPbI3 / siloxane film with a PLQY of 99% and an emission peak of 687 nm was obtained. Additionally, the HS-CsPbI3 / siloxane film emitted blue light (23 mW / cm²). 2 More than 1000 hours of T under ) 90 It exhibits excellent photostability over its lifespan.

[0189] FIG. 25 is a graph illustrating the time-dependent stability (PL peak: 687 nm) of a hierarchical shell for stabilizing CsPbI3 perovskite nanocrystals according to an embodiment of the present invention, where FIG. 25(a) shows PLQY and FIG. 25(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2... indicates. As shown in Fig. 25(b), the PL peak of the HS-CsPbI3 / siloxane film remains the same even under blue light irradiation. In conclusion, referring to Fig. 25, it is shown that a hierarchical shell structure can be applied to fabricate bright and stable deep red CsPbI3 / PbSO4 / SiO2 / siloxane perovskite nanocrystalline films.

[0190] <Preparation Example 7: Preparation of a film containing perovskite nanocrystalline particles of a hierarchical core-shell-shell-shell structure>

[0191] The procedure for preparing the HS-FAPbI3 perovskite nanocrystalline film is as follows: 1) Prepare 10 mL of chloroform to prepare the FAPbI3 core. 2) Then, inject 0.3 mL of FAPbI3 precursor at room temperature. To prepare the FAPbI3 precursor, 137.6 mg of FAI, 184.4 mg of PbBr2, 4.8 mL of oleic acid, and 600 μl of oleylamine are dispersed in 4 mL of DMF. 3) After purification, a FAPbI3 perovskite nanocrystalline core stabilized with oleic acid and oleylamine is obtained. 4) Then, the FAPbI3 perovskite nanocrystalline core is treated with (APTES)2SO4 to obtain APTES-stabilized FAPbI3 / PbSO4 core-shell structured perovskite nanocrystals. The synthesized perovskite nanocrystals were further coated with SiO2 via the slow hydrolysis of TMOS / TEOS to form FAPbI3 / PbSO4 / SiO2 perovskite nanocrystals with a hierarchical shell structure. 5) To prepare the FAPbI3 / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) were condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-FAPbI3 / siloxane film was obtained with a PLQY of 94% and an emission peak of 783 nm. Additionally, the HS-FAPbI3 / siloxane film emitted blue light (23 mW / cm²). 2 More than 1000 hours of T under )90 It exhibits excellent photostability over its lifespan.

[0192] Fig. 26 is a graph showing the time-dependent stability (PL peak: 783 nm) of a hierarchical shell for stabilizing FAPbI3 perovskite nanocrystals, where Fig. 26(a) shows PLQY and Fig. 26(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 ... indicates. As shown in Fig. 26(b), the PL peak of the HS-FAPbI3 / siloxane film remains the same even under blue light irradiation. These results indicate that the hierarchical shell can stabilize the lattice of FA-based perovskite nanocrystals. In conclusion, referring to Fig. 26, it is shown that bright near-infrared (NIR) FAPbI3 / PbSO4 / SiO2 / siloxane perovskite nanocrystal films can be fabricated by applying a hierarchical shell structure.

[0193] <Preparation Example 8: Preparation of a film containing perovskite nanocrystalline particles of a hierarchical core-shell-shell-shell structure>

[0194] HS-Cs 0.5 FA 0.5 The procedure for preparing PbI3 perovskite nanocrystalline films is as follows: 1) Mix 17 mg of FAPbI3 and 21.6 mg of CsPbI3 in 5 mL of toluene. 2) Subsequently, add 5 μl of oleic acid and quickly add 3 μl of oleic acidamine. 3) After stirring for 30 minutes and purification, CsPbI3 stabilized with oleic acid and oleylamine is obtained. 0.5 FA 0.5 A PbI3 perovskite nanocrystalline core is obtained. 4) Subsequently, Cs using (APTES)2SO4 0.5 FA 0.5 APTES-stabilized Cs by treating PbI3 perovskite nanocrystalline cores 0.5 FA 0.5Perovskite nanocrystals with a PbI3 / PbSO4 core-shell structure were obtained and additionally coated with SiO2 via slow hydrolysis of TMOS / TEOS to obtain Cs with a hierarchical shell structure 0.5 FA 0.5 Forms PbI3 / PbSO4 / SiO2 perovskite nanocrystals. 5) Cs 0.5 FA 0.5 To prepare a PbI3 / PbSO4 / SiO2 / siloxane resin, diphenylsilanediol (DPSD) and 3-methacryloxypropyltrimethoxysilane (MPTMS) are condensed in the presence of a Ba(OH)2 catalyst, followed by the introduction of a photoinitiator into the siloxane resin. Finally, an HS-Cs with a PLQY of 98% and an emission peak of 737 nm is produced. 0.5 FA 0.5 A PbI3 / siloxane film was obtained. In addition, HS-Cs 0.5 FA 0.5 PbI3 / siloxane film is blue light (23 mW / cm²) 2 More than 1000 hours of T under ) 90 It exhibits excellent photostability over its lifespan.

[0195] Fig. 27 is Cs 0.5 FA 0.5 A graph plotting the time-dependent stability (PL peak: 737 nm) of a hierarchical shell for stabilizing PbI3 perovskite nanocrystals, where Fig. 27(a) shows PLQY and Fig. 27(b) shows the spectral stability (23 mW / cm²) under blue light irradiation. 2 It indicates ). As shown in Fig. 27(b), the PL peak of the HS-FAPbI3 / siloxane film remains the same even under blue light irradiation. These results indicate that the hierarchical shell can stabilize the lattice of FA-based perovskite nanocrystals. In conclusion, referring to Fig. 27, the bright and stable mixed cation Cs 0.5 FA 0.5 This shows that a hierarchical shell structure can be applied to fabricate PbI3 / PbSO4 / SiO2 / siloxane perovskite nanocrystalline films.

[0196] According to another embodiment of the present invention, a hybrid film of CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals with a hierarchical shell structure and siloxane can be directly patterned through photolithography.

[0197] FIG. 28 is a schematic diagram showing the process of performing hybrid photolithography of hierarchical shell-stabilized perovskite nanocrystals (HS-PeNC) and siloxane according to one embodiment of the present invention.

[0198] Referring to Fig. 28(a), the patterning procedure is as follows: 1) A CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal-siloxane film is deposited via spin coating or bar coating. 2) The film is exposed to UV light for 3 to 10 seconds using a mask. 3) A pattern is obtained by developing in toluene or PGMEA (glophyllene glycol monomethyl ether acetate) for 30 seconds. At this time, the size of the fine pattern can be well adjusted by changing the mask size. Referring to Figs. 28(b) and 28(c), for example, 100 μm and 20 μm line micropatterns of CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals can be obtained. These patterns exhibit green emission with a PL peak of 518 nm and a PLQY of 84%.

[0199] FIG. 29 is a schematic diagram illustrating the process of performing photolithography on stabilized perovskite nanocrystals (HS-PeNC) using a ligand crosslinking agent (Lixer) according to an embodiment of the present invention. Referring to FIG. 29, the process of performing photolithography on CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals with a hierarchical shell structure using a ligand crosslinking agent is as follows: 1) CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals are mixed with 2 wt% 2-LiXer (ethane-1,2-diylbis(4-azido-2,3,5,6-tetrafluorobenzoate)) in toluene. 2) A film is deposited by spin-coating the above-mentioned mixture. 3) The mixture is exposed to 254 nm UV light using a mask for 10 seconds. 4) A pattern is obtained by developing in toluene for 30 seconds. At this time, the size of the fine pattern can be well adjusted by changing the mask size. For example, fine patterns of 500 nm, 1 µm, 2 µm, 5 µm, 10 µm, 20 µm, 50 µm, 100 µm, 500 µm, 1 mm, 2 mm, and 5 mm can be obtained. These patterns show green emission with a PL peak of 518 nm, PLQY of 81%, and FWHM of 21 nm.

[0200] As is known, Pb toxicity is one of the major concerns regarding the commercial application of perovskite nanocrystals. According to the present invention, since the perovskite nanocrystal core is covered with a hierarchical shell structure, Pb leakage is completely blocked, thereby eliminating the toxicity of the perovskite nanocrystals.

[0201] FIG. 30 is a graph showing the results of a biocompatibility evaluation of an HS-CsPbBr3 / siloxane film using C2C12 mouse myoblast cells according to one embodiment of the present invention. Specifically, it shows the results of a colorimetric CCK-8 analysis to evaluate the living cell populations on the surface of the PeNC / siloxane film and the control group (polystyrene cell culture dish). The living cell population on day 1 of the control group was set to 1.0. Data are expressed as mean ± standard deviation (n=6). The inset is a photograph of a perovskite nanocrystal-(core-shell)-siloxane film (diameter: 15 mm) in a cell growth medium. Referring to FIG. 30, the biocompatibility evaluation results showed that the HS-CsPbBr3 / siloxane film exhibited the highest biocompatibility, proving that it is significantly superior to CsPbBr3, CsPbBr3 / siloxane films, as well as commonly used polystyrene (PS). These results indicate effective encapsulation of a hierarchical shell, providing a promising method for commercializing perovskite nanocrystals. Perovskite nanocrystal films with such a hierarchical shell structure are stable, bright, color-tunable, and low-toxicity, making them good candidates for reinforcing films for LCD-based displays.

[0202] FIG. 31 is a schematic diagram illustrating the configuration (a) of a hierarchical shell-stabilized perovskite nanocrystal (HS-PeNC) color conversion layer film for a backlight display, the white light spectrum (b) of a green and red HS-PeNC-based tablet, and the green, red, and blue images (c) of the perovskite tablet.

[0203] As shown in FIG. 31(a), HS-CsPbBr3 green and HS-HS-CsPbBr 1.2 I 1.8 Red perovskite nanocrystals are mixed as a color conversion layer. As shown in Fig. 31(b), HS-CsPbBr3 and HS-CsPbBr 1.2 I 1.8The perovskite nanocrystals maintain their unique colors in the mixture, indicating that the hierarchical shell completely suppresses ion exchange between the green and red perovskite nanocrystals. The PL peak wavelength and FWHM of the red film are 634 nm and 32 nm, respectively. The PL peak wavelength and FWHM of the green film are 514 nm and 17 nm, respectively. These mixed perovskite nanocrystal films can be integrated with a blue backlight to generate white light in an LCD-based tablet. As shown in Fig. 31(c), the tablet displays a high-quality RGB image.

[0204] FIG. 32 is a schematic diagram illustrating the structure of a color conversion layer pattern of a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure for a high-resolution display according to an embodiment of the present invention. As shown in FIG. 32, the perovskite nanocrystal micropattern can be used as a color conversion layer for a blue backlight for a high-resolution micro LED display system. In an embodiment of the present invention, the pixel comprises a red subpixel, a green subpixel, and a blue subpixel. The red subpixel is composed of a perovskite nanocrystal or quantum dot material with a red hierarchical shell structure. The green subpixel is formed of a perovskite nanocrystal material with a green hierarchical shell structure. The blue subpixel is transparent to the blue light of the backlight. The blue backlight may be an Organic Light-Emitting Diode (OLED), a Quantum Dot LED (QLED), a Mini LED, or a Micro LED.

[0205] Specifically, in a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CsPbBrI2 / PbSO4 / SiO2 perovskite nanocrystals (emission range 610 to 640 nm) are deposited as red subpixels to convert blue light into red light. At the same time, a transparent blue subpixel that generates blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0206] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CdSe / ZnS (emission range 610 to 640 nm) is deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0207] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CsPbBrI2 / PbSO4 / SiO2 (emission range 610 to 640 nm) is deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0208] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CdSe / ZnS perovskite nanocrystals (emission range 610 to 640 nm) are deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0209] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CsPbBrI2 / PbSO4 / SiO2 (emission range 610 to 640 nm) is deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0210] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CdSe / ZnS quantum dots (emission range 610 to 640 nm) are deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0211] In a blue micro LED (emission range 445 to 470 nm), CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals (emission range 510 to 535 nm) can be deposited as green subpixels to convert blue light into green light. Similarly, CdSe / ZnS (emission range 610 to 640 nm) is deposited as red subpixels to convert blue light into red light. At the same time, transparent blue subpixels that generate blue light can be placed, and R, G, and B subpixels can generate white light for the display.

[0212] FIG. 33(a) is a pixelated electroluminescent device including a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure (HS-perovskite nanocrystal) according to one embodiment of the present invention, FIG. 33(b) is a quantum emitter, and FIG. 33(c) is a schematic diagram showing a perovskite nanocrystal with a hierarchical core-shell-shell-shell structure (HS-PeNC) used in such a luminescent device.

[0213] As illustrated in FIG. 33(a), the perovskite nanocrystal stabilized with a stable and bright hierarchical shell according to the present invention can be used as a light emitter for an electroluminescent LED. Specifically, the light emitter for the electroluminescent LED may be formed with a device structure of ITO / PEDOT:PSS:PFI / CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal / TBTB / TPBI / LiF / Al. The light emitter for the electroluminescent LED may have an EL peak at 518 nm, a FWHM of 21 nm, and an EQE of 1.3%, and may emit green light.

[0214] As shown in FIG. 33(b), the stable and bright hierarchical shell-stabilized perovskite nanocrystal of the present invention can be used as a pixelated emitter for an electroluminescent LED. Specifically, the pixelated emitter for the electroluminescent LED may be formed with a device structure of ITO / PEDOT:PSS:PFI / patterned CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal / TBTB / TPBI / LiF / Al. The pixelated emitter for the electroluminescent LED may have an EL peak at 518 nm, a FWHM of 21 nm, and an EQE of 0.76%, and may emit green light. The pixel size of the patterned CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystal can be 2 µm, 5 µm, 10 µm, 20 µm, 50 µm, 100 µm, 500 µm, 1 mm, 2 mm, or 5 mm.

[0215] As illustrated in FIG. 33(c), the perovskite nanocrystals stabilized with a stable and bright hierarchical shell according to the present invention can be used as emitters for single-photon emission sources. Specifically, 0.2 μg / mL CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals can be dispersed in toluene containing 30 mg / mL PMMA, and then spin-coated to produce monodisperse perovskite nanocrystals in a PMMA matrix.

[0216] Single CsPbBr3 / PbSO4 / SiO2 exhibits stable green emission at 515 nm for more than 600 seconds under excitation by a continuous wave (CW) or pulsed laser (405 or 488 nm). When the second-order correlation was measured under 405 nm CW laser excitation, g2 (t=0) was 0.3, indicating that single photon emission can be observed in CsPbBr3 / PbSO4 / SiO2 perovskite nanocrystals.

[0217] FIG. 34 is a schematic diagram showing the structure of an oxygen saturation meter comprising a perovskite nanocrystal (HS-PeNC) with a hierarchical core-shell-shell-shell structure according to one embodiment of the present invention. As shown in FIG. 34, the stable and bright hierarchical shell-stabilized perovskite nanocrystal (HS-PeNC) of the present invention can be used as a color conversion layer of a blue micro LED or a blue OLED for a wearable pulse oximeter (oxygen saturation meter).

[0218] Specifically, the oxygen saturation meter may be composed of two light sources (green and red light from a perovskite nanocrystal color conversion layer integrated with a blue micro-LED) and one Si photodetector. The NIR and red films can convert light to 465 nm, and the blue light to 520 nm and 620 nm, respectively. The detection range of the Si photodetector is 300 to 1100 nm.

[0219] A pulse oximeter uses LEDs to send red and NIR light through tissues and then uses a photodetector to measure the intensity of the transmitted light, and may calculate blood oxygen saturation, which indicates the degree to which oxygen binds to hemoglobin in the blood, by comparing the absorption of red light and near-infrared light.

[0220] Specifically, a pulse oximeter may measure blood oxygen saturation through the following steps: 1) red light and near-infrared light are transmitted through the skin, 2) a photodetector receives the transmitted light and measures its intensity after it passes through the tissue, 3) calculates the absorption rate of the red light and near-infrared light, and 4) calculates the blood oxygen saturation using the absorption rate.

[0221] The heart rate can be calculated using the following formula (3).

[0222] Heart rate = f × 60 … … Equation (3)

[0223] The above f is the frequency of the maximum value near 1 Hz obtained by Fourier transforming the PPG (photoplethysmography) signal.

[0224] SpO2 can be calculated using the following formula (4).

[0225] … … Equation (4)

[0226] The above CH b O2 and CH b are the concentrations of hemoglobin and deoxyhemoglobin in human blood, respectively.

[0227] According to Lambert-Beer's law, SpO2 can be calculated using the following equation (5).

[0228]

[0229] … … Equation (5)

[0230] The above ε ( Hb, Red ) and ε ( Hb,NIR ) are the molar absorption rates of HbO2 at the red and NIR wavelengths, respectively.

[0231] In one general scenario, perovskite nanocrystals can be used to emit red (λ=620 nm) and green (λ=520 nm) light coupled with a commercial Si photodetector.

[0232] Simplifying the above equation (5) gives SpO2 = A - BR.

[0233] The above A is ε ( Hb, Red ) / (ε ( Hb, Red ) -ε ( HbO2, Red ) ) and B is ε ( Hb, NIR ) / (ε ( Hb, Red ) -ε ( HbO2, Red )), R is the ratio of absorbed red (AC1 / DC1) and NIR (AC2 / DC2) light. Here, the calculation is simplified by removing the DC component. That is, R is determined by the reflected red (AC1) and green (AC2) light intensities as shown in Equation (6) below.

[0234] … … Equation (6)

[0235]

[0236] In the above equation (6), SpO2 is fitted as a quadratic curve according to the following equation (7).

[0237] … … Equation (7)

[0238] Using an emitter containing perovskite nanocrystals, the heart rate was calculated to be 71 bpm, which is consistent with the result obtained using a commercial pulse oximeter (72 bpm). In addition, the calculated SpO2 was 98.7%, which is consistent with the result obtained using a commercial pulse oximeter.

[0239] As described above, the perovskite nanocrystal stabilized with a stable and bright hierarchical shell according to the present invention, the light-emitting film containing the same, and the micro-pattern formed by optical patterning the same can be actively utilized in various types of light-emitting devices, such as color conversion layers for LCD, LED, and VR / AR display systems, light emitters for electroluminescent LEDs, and pulse oximeters, and devices containing the same can effectively improve light-emitting efficiency and optical safety.

[0240]

[0241] Although the present invention has been described in detail above with reference to preferred embodiments, it is obvious to those skilled in the art that the present invention may be modified or altered in various ways without departing from the spirit and scope of the invention; therefore, all such modifications and variations should be interpreted as being included within the scope of protection of the present invention. The true scope of protection of the present invention is determined by the claims set forth below rather than by the detailed description above, and the scope of protection of the present invention should be interpreted as the claims and their equivalents.

Claims

1. Perovskite nanocrystal core; A first inorganic shell surrounding the above-mentioned perovskite nanocrystal core; A second weapon shell surrounding the first weapon shell; and Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure characterized by including an organic / polymer shell surrounding the second inorganic shell.

2. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure according to claim 1, characterized in that the perovskite nanocrystal core is manufactured by a solution process, coated with a ligand, and formed with a diameter exceeding the exciton Bohr diameter.

3. In claim 1, the perovskite nanocrystal core comprises one or more materials selected from CsBX3, RbBX3, MABX3, FABX3, CsRbBX3, RbFAPbX3, RbMAPbX3, RbGAPbX3, CsFABX3, CsMABX3, MAFABX3, CsGABX3, FAGABX3, RbCsFABX3, RbCsMABX3, RbMAFABX3, RbCsGABX3, RbFAGABX3, CsMAFAPbX3, and CsRbMAFAPbX3, wherein X is chlorine, bromine, iodine, or a mixture thereof, B is at least one metal element selected from Pb, Sn, Ge, Bi, Sb, Ag, Na, In, Bi, Mg, and Mn, MA is methylamine, and FA is Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure characterized by being formamidine and GA being guanidinium.

4. A perovskite nanocrystal with a hierarchical core-shell-shell-shell structure according to claim 1, characterized in that when the perovskite nanocrystal core and the first inorganic shell are epitaxially grown together, the lattice mismatch between the perovskite nanocrystal core and the first inorganic shell is greater than 0% and less than or equal to 25%.

5. Colloidal perovskite nanocrystal of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the first inorganic shell forms a type-I heterojunction with the perovskite nanocrystal core.

6. Colloidal perovskite nanocrystal of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the first inorganic shell has a band gap 0.1 to 5.0 eV larger than the band gap of the perovskite nanocrystal core.

7. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the first inorganic shell comprises at least one selected from metal sulfates and metal sulfides.

8. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the bandgap of the second inorganic shell is 3.0 eV to 10.0 eV without absorption of visible light.

9. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure according to claim 1, wherein the second inorganic shell comprises one or more selected from the group consisting of SnO2, ZrO2, NiO, SiO2, TiO2, and Al2O3.

10. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the bandgap of the organic / polymer shell is 3.0 eV to 10.0 eV without absorption of visible light.

11. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, wherein the organic / polymer shell comprises one or more selected from the group consisting of siloxane, PS, PMMA, PVP, PVDF, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET).

12. Step of forming a perovskite nanocrystal core; A step of reacting the core with the first weapon shell precursor to form a core-first weapon shell structure by arranging the first weapon shell in a manner that surrounds the core; A step of reacting the core-first weapon shell and the second weapon shell precursor to form a core-first weapon shell-second weapon shell structure by arranging the second weapon shell in a manner that surrounds the first weapon shell; A method for preparing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized by comprising the step of reacting the core-first inorganic shell-second inorganic shell with an organic / polymer ligand precursor to form a core-first inorganic shell-second inorganic shell-organic / polymer shell structure in which the organic / polymer shell is arranged to surround the second inorganic shell.

13. A method for preparing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, the core-shell interface and the shell-shell interface are bonded by coordination bonding, covalent bonding, or ionic bonding.

14. A method for manufacturing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, the thickness of the first inorganic shell is 0.5 nm to 20 nm.

15. A method for manufacturing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, the thickness of the second inorganic shell is 0.5 nm to 20 nm.

16. A method for preparing colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, the thickness of the organic / polymer shell is 0.5 nm to 20 nm.

17. A method for preparing colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, the colloidal perovskite nanocrystals are stabilized PeNC / PbSO4 / SiO2 / siloxane perovskite nanocrystals with a hierarchical core-shell-shell-shell structure.

18. A method for preparing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 12, oleylamine or oleic acid is used as a surfactant to stabilize the colloidal perovskite nanocrystals.

19. In claim 12, the step of forming the perovskite nanocrystal core is, A process of forming a first solution by mixing PbBr2 and an organic ligand in a first solvent; A process of forming a second solution by mixing Cs and a surfactant in a second solvent; A process of forming a CsPbBr3 perovskite nanocrystal core by mixing the first solution and the second solution; A process for purifying the above CsPbBr3 perovskite nanocrystal core; and A method for preparing colloidal perovskite nanocrystals with a hierarchical core-shell-shell-shell structure, characterized by including a process of dispersing the above-mentioned CsPbBr3 perovskite nanocrystal core in a third solvent.

20. In claim 12, the method for preparing the colloidal perovskite nanocrystal comprises the step of reacting (APTES)2SO4 with the perovskite nanocrystal to obtain a PeNC / PbSO4 / APTES core-shell structure; and A method for preparing colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized by including the step of obtaining stabilized PeNC / PbSO4 / SiO2 perovskite nanocrystals of a double-shell structure by adding TMOS (tetraethyl orthosilicate) or TEOS (tetraethyl orthosilicate) to the above PeNC / PbSO4 / APTES core-shell structure.

21. A method for preparing a (APTES)2SO4 precursor by reacting the above APTES and H2SO4 in a non-polar solvent at a molar ratio of 2:1 in claim 20.

22. A method for manufacturing a PeNC / PbSO4 / SiO2 / siloxane light-emitting film having a hierarchical core-shell-shell-shell structure, characterized by forming the film by applying a mixture comprising colloidal perovskite nanocrystals having a hierarchical core-shell-shell-shell structure according to claim 1 and a siloxane polymer resin as a bar coating on a base substrate, followed by photopolymerization.

23. A method for manufacturing a PeNC / PbSO4 / SiO2 / siloxane light-emitting film with a hierarchical core-shell-shell-shell structure according to claim 22, wherein the siloxane polymer resin is formed by condensing diphenylsilanediol and 3-methacryloxypropyltrimethoxysilane in the presence of a Ba(OH)2 catalyst and then adding a photoinitiator.

24. A method for forming a micropattern of a siloxane polymer hybrid resin and a colloidal perovskite nanocrystal having a hierarchical core-shell-shell-shell structure, comprising the step of directly patterning the emitting film containing the colloidal perovskite nanocrystal having a hierarchical core-shell-shell-shell structure according to claim 1 through photolithography and then developing the emitting film.

25. A method for forming a micropattern of a siloxane polymer hybrid resin and a colloidal perovskite nanocrystal having a hierarchical core-shell-shell-shell structure, wherein the pixel size of the micropattern is 500 nm, 1 µm, 2 µm, 5 µm, 10 µm, 20 µm, 50 µm, 1 µm, 500 µm, 1 mm, 2 mm, or 5 mm, in accordance with claim 24.

26. A method for forming a micropattern of a colloidal perovskite nanocrystal with a hierarchical core-shell-shell-shell structure and a siloxane polymer hybrid resin, characterized in that, in claim 24, the perovskite nanocrystal is mixed with a ligand crosslinking agent (LiXer) to photocrosslink the perovskite nanocrystal.

27. In paragraph 26, the ligand crosslinking agent is 2-LiXer(ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate)); 4-LiXer(2,2-bis(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate), IP-4-LiXer(2,2-bis(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5-trifluoro-6-isopropylbenzoate))); 6-LiXer(2-(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)-2-((3-((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)-2,2-bis(((4-azido-2,3,5,6-tetrafluorobenzoyl)oxy)methyl)propoxy)methyl)propane-1,3-diylbis(4-azido-2,3,5,6-tetrafluorobenzoate)); A method for forming a micropattern of a colloidal perovskite nanocrystal with a hierarchical core-shell-shell-shell structure and a siloxane polymer hybrid resin, characterized by comprising one or more selected from the group consisting of IP-6-LiXer(2-((3-((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)-2,2-bis(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propoxy)methyl)2-(((4-azido-2,3,5-trifluoro-6-isopropylbenzoyl)oxy)methyl)propane-1,3-diyl bis(4-azido-2,3,5-trifluoro-6-isopropylbenzoate)).

28. A luminescent film produced by the method for producing a PeNC / PbSO4 / SiO2 / siloxane luminescent film having a hierarchical core-shell-shell-shell structure according to claim 22.

29. A micropattern produced by the method for forming a micropattern of a colloidal perovskite nanocrystal with a hierarchical core-shell-shell-shell structure and a siloxane polymer hybrid resin according to claim 24.

30. Colloidal perovskite nanocrystals of a hierarchical core-shell-shell-shell structure, characterized in that, in claim 1, the colloidal perovskite nanocrystals are used as an electroluminescent LED, a single photon emitter, or an emitter for an oxygen saturation meter.

31. In paragraph 28, the light-emitting film is a light-emitting film used as a color conversion layer for LCD, Mini LED, Micro LED, and VR / AR display systems.

32. In paragraph 29, the micro pattern is a micro pattern used as a color conversion layer for LCD, Mini LED, Micro LED, and VR / AR display systems.

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