KR102546054B1 - Purification method of organic-inorganic hybrid perovskite quantum dot having enhanced stability, and self-healable and stretchable color filter comprising by the same - Google Patents

Abstract

The present invention relates to a stable organic-inorganic hybrid perovskite quantum dot, a method for producing the same, and a self-healing and stretchable color filter including the same. By doing so, the methyl acetate anion was bound to the surface of the perovskite nanocrystal to produce stabilized perovskite quantum dots in high yield, and when a composite film of perovskite and elastomer with improved stability was formed, perovskite It is possible to manufacture a color filter having self-healing properties and stretchability while maintaining the optical properties of.

Description

Purification method of organic-inorganic hybrid perovskite quantum dots with improved stability and self-healing and stretchable color filter containing purified organic-inorganic hybrid perovskite quantum dots {Purification method of organic-inorganic hybrid perovskite quantum dot having enhanced stability , and self-healable and stretchable color filter comprising by the same}

The present invention relates to quantum dots, and more particularly to perovskite quantum dots.

Metal halide perovskite quantum dots are in the spotlight because they can simply control the molecular size and emission wavelength simply by controlling the temperature or changing the composition during synthesis, and the synthesis cost is low. In particular, organic-inorganic hybrid perovskite quantum dots can produce color filters using high luminance and a narrow half-width, and can increase the color gamut of existing displays.

However, the organic-inorganic hybrid perovskite quantum dot is a material whose crystal is composed of ionic bonds, and its optical properties and stability are easily affected by the external environment, so when applied as an electronic device, it constitutes an organic-inorganic hybrid perovskite, Ions may move to the surrounding laminated parts, and the function and lifespan of the electronic device may deteriorate.

Accordingly, research to increase the stability of organic-inorganic hybrid perovskite quantum dots is required.

On the other hand, the recently commercialized flexible/foldable display can reduce the area and is easy to carry, and when in use, the display can be unfolded to use a large area. Compared to displays using existing glass, it is lighter and has flexibility, so it has the advantage of not breaking. However, an organic light emitting diode device using an organic light emitting body has a wide spectrum, has poor color purity, and has a disadvantage in that it is expensive. Existing flexible, foldable, and rollable displays can only be deformed in a specific area or direction and can only be moved within a limited radius of curvature, so there is a limit to extending beyond the bendable radius of curvature or to a wider area. In addition, existing displays have a problem in that a protective film must be attached to prevent scratches occurring in daily life. In addition, if a crack occurs in an element within a display element due to an impact or scratch, it is difficult to find or restore the crack to its original state.

Accordingly, the development of a new display material capable of self-healing and stretching is required.

Republic of Korea Patent Publication No. 10-2018-0002716

The problem to be solved by the present invention is to provide organic-inorganic hybrid perovskite quantum dots with improved stability.

Another problem to be solved by the present invention is to provide a method for producing organic-inorganic hybrid perovskite quantum dots having improved stability.

Another problem to be solved by the present invention is to provide a self-healing and stretchable new color filter comprising organic-inorganic hybrid perovskite quantum dots with improved stability.

Another problem to be solved by the present invention is to provide a method for manufacturing the color filter.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, one aspect of the present invention provides organic-inorganic hybrid perovskite quantum dots with improved stability. The organic-inorganic hybrid perovskite quantum dots with improved stability include organic-inorganic hybrid perovskite nanocrystals dispersed in an organic solvent; and a plurality of ligands surrounding the organic-inorganic hybrid perovskite nanocrystal, wherein at least one of the ligands is an acetate anion (CH ₃ COO ^- ).

The organic-inorganic hybrid perovskite nanocrystal may include a structure represented by Formula 1 below.

[Formula 1]

ABX ₃

(In Formula 1 above,

Wherein A is organoammonium,

Wherein B is a metal material,

The X is a halogen element.)

A is methylammonium, formammonium, guanidinium, (CH(NH ₂ ) ₂ , C _x H _2x+1 (CNH ₃ ), (CH ₃ NH ₃ ) _n , ((C _x H _2x+1 ) _n NH ₃ ) _n (CH ₃ NH ₃ ) _n , R(NH ₂ ) ₂ (Where R=alkyl), (C _n H _2n+1 NH ₃ ) _n , (CF ₃ NH ₃ ), (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n , (C _n F _2n+1 NH ₃ ) _n (where n and x are integers from 1 to 100) or derivatives thereof, wherein B is Pb, Mn, Cu, Ga, Ge, In, Al, Sb, Bi, Po, Sn, Eu, Yb, Ni, Co, Fe, Cr, Pd, Cd, Ca, Sr or a combination thereof, and X may be Cl, Br, I or a combination thereof.

Among the ligands, the ligands other than the acetate anion (CH ₃ COO ^- ) may be selected from the group consisting of an amine ligand, an organic acid, a phosphine ligand, a sulfide ligand, a secondary ligand, and a tridentate ligand.

Among the ligands, the ligands other than the acetate anion (CH ₃ COO ^- ) are hexylamine, octylamine, decylamine, dodecylamine, oleylamine, and hexanoic. Hexanoic acid, octanoic acid, decanoic acid, undecanoic acid, lauric acid, hexadecanoic acid, Octadecanoic acid, oleic acid, trioctylphosphine, trioctylphosphine oxide, 1,2-ethanedithiol and 3- (N,N-dimethyloctadecylammonio)propanesulfonate.

The acetate anion (CH ₃ COO ^- ) may stabilize the perovskite quantum dots by ionic bonding to the surface of the organic-inorganic hybrid perovskite quantum dots.

The organic-inorganic hybrid perovskite quantum dots may have a cubic crystal structure.

The average particle size of the organic-inorganic hybrid perovskite quantum dots may be 1 nm to 100 nm.

In addition, another aspect of the present invention provides a method for producing organic-inorganic hybrid perovskite quantum dots having improved stability. The method for preparing organic-inorganic hybrid perovskite quantum dots having improved stability includes preparing a first solution by dissolving organic-inorganic hybrid perovskite precursors and organic ligands in a protic solvent; mixing the first solution with an aprotic solvent to form a second solution in which organic-inorganic hybrid perovskite quantum dots are formed; And methyl acetate is added to the second solution, centrifuged, and redispersed in an organic solvent to stabilize organic-inorganic hybrid perovskite quantum dots by binding acetate anion (CH ₃ COO ^- ) to the surface of organic-inorganic hybrid perovskite nanocrystals. It includes the step of forming.

In this case, when methyl acetate is added to the second solution, the volume ratio of the second solution to methyl acetate may be 1:1 to 1:5.

In addition, another aspect of the present invention provides a color filter including organic-inorganic hybrid perovskite quantum dots having improved stability. The color filter may include organic-inorganic hybrid perovskite quantum dots having improved stability; and a thermoplastic elastomer in which the organic-inorganic hybrid perovskite quantum dots are dispersed.

The color filter may be in the form of a film formed by dispersing organic-inorganic hybrid perovskite quantum dots in a thermoplastic elastomer.

The thermoplastic elastomer is polyolefin, polysiloxane, polychloroprene, polysulfide, polyolefin copolymer elastomer, fluorocarbon elastomer, acrylonitrile block copolymer, polystyrene block copolymer, polyolefin copolymer, polyester copolymer, polyamide copolymer and It may be selected from the group consisting of polyurethane copolymers.

The thermoplastic elastomer may be polystyrene-block-polyisoprene-block-polystyrene (SIS) represented by Formula 2 below.

[Formula 2]

(In Formula 2,

x, y and z are each an integer greater than or equal to 1;

The number average molecular weight (Mn) of Formula 2 is 1,000 to 1,000,000,

The styrene content in the compound of Formula 2 is 10 to 25 wt.%.)

The color filter may have elasticity, and self-healing may be possible by having self-restoring ability due to scratches and damage.

In addition, another aspect of the present invention provides a method for manufacturing a color filter including organic-inorganic hybrid perovskite quantum dots having improved stability. The method of manufacturing the color filter includes preparing a perovskite-elastomer composite dispersion by mixing the organic-inorganic hybrid perovskite quantum dots and the elastomer in a non-polar solvent; and forming a color filter in the form of a film by applying the perovskite-elastomer composite dispersion on a substrate and drying the dispersion.

The non-polar solvent is an alkane selected from the group consisting of butane, hexane, octane and cyclohexane; an aromatic compound selected from the group consisting of toluene, chlorobenzene and dichlorobenzene; And it may be any one selected from a halogen compound selected from the group consisting of chloroform, dichloroethane, and dichloroethene, or a mixed solvent thereof.

Through the present invention, the effectiveness of methyl acetate as a cleaning solvent was demonstrated to obtain stable organic-inorganic hybrid perovskite quantum dots at a high production rate, and a stretchable and self-healing color filter can be produced using the perovskite quantum dots. .

Specifically, during the purification process, freshly synthesized organic-inorganic hybrid Perovskite quantum dots have previously been found to be severely damaged when washed with polar protons and aprotic non-solvents (such as MeOH and acetone). On the other hand, such an adverse effect did not occur when washing with methyl acetate, and the resulting organic-inorganic hybrid perovskite quantum dots eventually showed a high production rate and excellent long-term stability with respect to their important optical properties, colloidal dispersibility, and crystallinity.

At this time, methyl acetate molecules cause a hydrolysis reaction with water to form acetate anions (CH ₃ COO ^- ), and the acetate anions do not destroy the organic/inorganic perovskite quantum dot core and form organic/inorganic hybrid Rather, better surface passivation was induced by partially replacing the original surface ligands associated with perovskite quantum dots. Accordingly, the organic-inorganic hybrid perovskite quantum dots washed with methyl acetate had a stable cubic crystal structure, and showed excellent long-term stability by maintaining their crystal structure and size uniformly even after a long period of about 5 months in a solution state. .

In addition, a free-standing color filter with excellent stretchability and self-healing properties can be produced by preparing a perovskite quantum dot-elastomeric composite film using organic-inorganic hybrid perovskite quantum dots washed with methyl acetate. This filter can then be used to fabricate a white LED device with a wide color gamut.

1 is a schematic diagram of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention.
3 is a reaction between the surface of the organic-inorganic hybrid perovskite quantum dots and methyl acetate during the washing process using methyl acetate as a cleaning solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention It is a schematic diagram showing the mechanism.
4 is a schematic diagram of a self-healing and stretchable quantum dot-elastomeric composite film including organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention.
Figure 5 shows (a) production yield, and (b) of perovskite quantum dots prepared according to the washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention. Indicates UV absorbance.
Figure 6 is in the production of organic-inorganic hybrid perovskite quantum dots according to one embodiment and one comparative example of the present invention, the optical properties of the perovskite quantum dots prepared according to the washing solvent under UV light and the optical properties after 3 months represents a characteristic.
Figure 7 is in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention, (a) perovskite quantum dots (Neat) without using a washing solvent and as a washing solvent FTIR spectra of perovskite quantum dots (MeOAc_1 to MeOAc_7) prepared using various ratios of methyl acetate, methyl acetate, oleylamine, and oleic acid in pure solvents, and (b) an enlarged view of specific peaks thereof indicates
8 is a perovskite quantum dot (Neat) without using a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention, and various ratios as a washing solvent X-ray diffraction spectra of perovskite quantum dots (MeOAc_1 to MeOAc_7) freshly prepared using methyl acetate and perovskite quantum dots after 5 months (5 months) are shown.
9 shows (a) freshly prepared perovskite quantum dots and (b) 5 months using methyl acetate as a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention. This is a picture of the crystal structure of the perovskite quantum dot observed with a high-resolution transmission electron microscope.
10 shows (a) freshly prepared perovskite quantum dots and (b) 5 months using methyl acetate as a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention. The particle size distribution of perovskite quantum dots after
11 shows a color filter in the form of an organic-inorganic hybrid perovskite quantum dot-elastic composite film prepared according to an embodiment of the present invention and its optical properties under UV light.
12 is a photograph showing stretch and self-healing characteristics of a color filter manufactured according to an embodiment of the present invention.
13 is an optical micrograph showing before and after self-healing of shallow and deep scratches of a color filter manufactured according to an embodiment of the present invention.
14 shows cross-sectional height profiles of flaws before and after self-healing of deep flaws on a color filter manufactured according to an embodiment of the present invention.
15 shows a light emitting spectrum of an LED device manufactured according to an embodiment of the present invention, and the inset shows a thin film structure in which a commercially available blue light emitting device and a light emitting composite of quantum dots and an elastic body are laminated to implement white light.
16 shows CIE chromaticity coordinates of an LED device manufactured according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions may include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprise" or "having" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

Organic-inorganic hybrid perovskite quantum dots

One aspect of the present invention provides organic-inorganic hybrid perovskite quantum dots with improved stability.

1 is a schematic diagram showing the structure of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention.

Referring to FIG. 1, the organic-inorganic hybrid perovskite quantum dots 100 according to the present invention are organic-inorganic hybrid perovskite nanocrystals dispersed in an organic solvent and surrounding the organic-inorganic hybrid perovskite nanocrystals It includes a plurality of ligands, wherein at least one of the ligands is an acetate anion.

The organic-inorganic hybrid perovskite nanocrystal may include a structure represented by Formula 1 below.

[Formula 1]

ABX ₃

(In Formula 1 above,

Wherein A is organoammonium,

Wherein B is a metal material,

The X is a halogen element.)

Specifically, the A is methylammonium, formammonium, guanidinium, (CH(NH ₂ ) ₂ , C _x H _2x+1 (CNH ₃ ), (CH ₃ NH ₃ ) _n , ((C _x H _2x+1 ) _n NH ₃ ) _n (CH ₃ NH ₃ ) _n , R(NH ₂ ) ₂ (Where R=alkyl), (C _n H _2n+1 NH ₃ ) _n , (CF ₃ NH ₃ ), (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n , (C _n F _2n+1 NH ₃ ) _n (where n and x are integers from 1 to 100) or a derivative thereof;

Wherein B is Pb, Mn, Cu, Ga, Ge, In, Al, Sb, Bi, Po, Sn, Eu, Yb, Ni, Co, Fe, Cr, Pd, Cd, Ca, Sr, or combinations thereof;

The X may be Cl, Br, I or a combination thereof.

The organic-inorganic hybrid perovskite quantum dots 100 according to the present invention may include an organic-inorganic hybrid perovskite nanocrystal structure capable of being dispersed in an organic solvent. The organic solvent at this time may be a protic solvent or an aprotic solvent.

For example, the protic solvent includes dimethylformamide, gamma butyrolactone, N-methylpyrrolidone or dimethylsulfoxide, and the non-positive The magnetic solvent may include dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, xylene, toluene, cyclohexene or isopropyl alcohol.

The ligand surrounds the ABX ₃ nanocrystal constituting the perovskite quantum dots, and serves to enable the perovskite quantum dots to exist in a colloidal form in a solution phase. The ligand may be ionic bonded to the surface of the perovskite nanocrystal, coordinate bonded, or unbonded, but may surround the perovskite nanocrystal by electrostatic attraction or van der Waals attraction. .

The ligand is an amine ligand, an organic acid, a phosphine ligand, a sulfide ligand, a secondary ligand (bidentate ligand), a tertiary ligand (tridentate) ligand, etc. A ligand capable of presenting organic-inorganic hybrid perovskite nanocrystals in a colloidal form in a solution phase Anything can be used.

Specifically, the amine ligand may be an amine having a hydrocarbon chain including C ₅ ~ C ₂₀ linear or branched CC or C=C. For example, hexylamine, octylamine, decylamine, dodecylamine, oleylamine, etc. may be mentioned, but is not limited thereto.

The organic acid may be a C ₅ ~ C ₂₀ straight chain or branched hydrocarbon acid containing CC or C=C. For example, hexanoic acid, octanoic acid, decanoic acid, undecanoic acid, lauric acid, hexadecanoic acid acid (hexadecenoic acid), octadecanoic acid (octadecanoic acid), oleic acid (oleic acid), and the like, but are not limited thereto.

Trioctylphosphine and trioctylphosphine oxide may be used as the phosphine ligand, but are not limited thereto.

As the sulfide ligand, for example, ethanedithiol (1,2-ethanedithiol) may be used, and 3-(N,N-dimethyloctadecylammonio)propanesulfonate, which is an amphoteric material, may be used as a ligand. there is.

In addition, in the organic-inorganic hybrid perovskite quantum dots 100 according to the present invention, at least one of the ligands surrounding the ABX ₃ nanocrystal constituting the perovskite quantum dots is an acetate anion (CH ₃ ^COO- ) may be included. The acetate anion (CH ₃ COO ^- ) may be formed by causing a hydrolysis reaction of methyl acetate molecules with water when methyl acetate is used as a washing solvent in a washing process during preparation of organic-inorganic hybrid perovskite quantum dots. The formed acetate anion is organic-inorganic hybrid without destroying the organic-inorganic hybrid perovskite quantum dot core. By partially replacing the original surface ligands combined with the perovskite quantum dots, it shows the effect of inducing rather better surface passivation.

The acetate anion may stabilize the perovskite quantum dots by ionic bonding to the surface of the organic-inorganic hybrid perovskite quantum dots.

However, during the purification process, when washing with a conventional polar proton or aprotic non-solvent such as methanol or acetone, the organic-inorganic hybrid perovskite quantum dots are severely damaged by the decomposition of weak ionic bonds in the crystal by the polar solvent. Confirmed.

On the other hand, this adverse effect did not occur when washing with methyl acetate, and the resulting organic-inorganic hybrid perovskite quantum dots were produced at a high production rate, had a stable cubic crystal structure, and their It exhibited excellent long-term stability by maintaining a uniform crystal structure and size.

The average particle size of the organic-inorganic hybrid perovskite quantum dots may be 1 nm to 100 nm. More preferably, it may have a diameter of 10 nm to 100 nm, which is larger than the Bohr diameter and is not affected by the quantum confinement effect. On the other hand, the size of the quantum dots at this time means the size without considering the length of the ligand, that is, the size of only the organic-inorganic hybrid perovskite crystal excluding the ligand. The size of such quantum dots can be measured through transmission electron microscopy (TEM) and dynamic light scattering (DLS) methods.

The band gap energy of quantum dots having a diameter of 1 nm to 100 nm according to the present invention is characterized by being determined by the structure of the perovskite crystal, unlike inorganic quantum dot light emitting devices depending on the particle size according to the quantum confinement effect. .

If the size of the nanocrystal particle exceeds 100 nm, the exciton binding energy is reduced and the luminous efficiency is reduced because the exciton does not go to light emission due to thermal ionization and charge carrier delocalization at room temperature and is separated into free charges and disappears. can be reduced

In addition, the bandgap energy of the organic-inorganic hybrid perovskite quantum dots may be 1 eV to 5 eV. Since the energy bandgap of such organic-inorganic hybrid perovskite quantum dots is determined according to the constituent materials or crystal structure of the quantum dots, by adjusting the constituent materials of the A, B, and X combinations, for example, light having a wavelength of 200 nm to 1300 nm can emit.

The metal halide nanocrystal particles can achieve a very high photoluminance quantum yield (PLQY) of 80% or more and can implement a display with a full width at half maximum (FWHM) of 30 nm or less.

Manufacturing method of organic-inorganic hybrid perovskite quantum dots

In addition, another aspect of the present invention provides a method for producing the organic-inorganic hybrid perovskite.

2 is a flowchart showing a method for manufacturing an organic-inorganic hybrid perovskite according to an embodiment of the present invention.

Referring to Figure 2, the method for producing an organic-inorganic hybrid perovskite according to an aspect of the present invention

preparing a first solution by dissolving organic/inorganic hybrid perovskite precursors and organic ligands in a protic solvent (S100);

mixing the first solution with an aprotic solvent to form a second solution in which organic-inorganic hybrid perovskite quantum dots are formed (S200); and

Adding methyl acetate to the second solution, centrifuging, and redispersing in an organic solvent to form stabilized organic-inorganic hybrid perovskite quantum dots by binding acetate anions to the surface of organic-inorganic hybrid perovskite nanocrystals (S300) can include

That is, organic-inorganic hybrid perovskite quantum dots according to the present invention can be prepared through LARP (Ligand-assisted reprecipitation) synthesis.

Hereinafter, the manufacturing method according to the present invention will be described in detail step by step.

First, step S100 is a step of preparing a first solution by dissolving organic-inorganic hybrid perovskite precursors and organic ligands in a protic solvent.

The protic solvent at this time may include dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, or dimethylsulfoxide, but is limited thereto. It is not.

At this time, the organic-inorganic hybrid perovskite precursor may be prepared by combining AX and BX ₂ at a predetermined ratio in order to form an organic-inorganic hybrid perovskite having a three-dimensional crystal structure of the above-described ABX ₃ structure. That is, the first solution may be formed by dissolving AX and BX ₂ in a protic solvent at a predetermined ratio. For example, a first solution in which ABX ₃ organic-inorganic hybrid perovskite is dissolved may be prepared by dissolving AX and BX2 in a 1:1 ratio in a protic solvent.

The organic ligand is an amine ligand, an organic acid, a phosphine ligand, a sulfide ligand, a secondary ligand (bidentate ligand), a tertiary ligand (tridentate ligand), etc. Organic-inorganic hybrid perovskite nanocrystals capable of existing in a colloidal form in a solution phase Any ligand can be used.

Specifically, the amine ligand may be an amine having a hydrocarbon chain including C ₅ ~ C ₂₀ linear or branched CC or C=C. For example, hexylamine, octylamine, decylamine, dodecylamine, oleylamine, etc. may be mentioned, but is not limited thereto.

The organic acid may be a C ₅ ~ C ₂₀ linear or branched hydrocarbon acid containing CC or C═C. For example, hexanoic acid, octanoic acid, decanoic acid, undecanoic acid, lauric acid, hexadecanoic acid acid (hexadecenoic acid), octadecanoic acid (octadecanoic acid), oleic acid (oleic acid), and the like, but are not limited thereto.

Trioctylphosphine and trioctylphosphine oxide may be used as the phosphine ligand, but are not limited thereto.

As the sulfide ligand, for example, ethanedithiol (1,2-ethanedithiol) may be used, and 3-(N,N-dimethyloctadecylammonio)propanesulfonate, which is an amphoteric material, may be used as a ligand. there is.

Next, step S200 is a step of mixing the first solution with an aprotic solvent to form a second solution in which organic-inorganic hybrid perovskite quantum dots are formed.

At this time, the first solution may be stirred. For example, organic-inorganic hybrid perovskite quantum dots may be formed by rapidly adding the first solution under vigorous stirring to an aprotic solvent.

At this time, the aprotic solvent is dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, xylene, toluene, cyclohexene or isopropyl alcohol. It can be used, but is not limited thereto.

At this time, when the first solution is mixed with an aprotic solvent, organic-inorganic hybrid perovskite nanocrystals are precipitated due to the difference in solubility. And while the ligand stabilizes the surface of the precipitated organic-inorganic hybrid perovskite nanocrystals, a colloidal solution in which well-dispersed organic-inorganic hybrid perovskite quantum dots are formed is created. Thus, organic-inorganic hybrid perovskite quantum dots including organic-inorganic hybrid perovskite nanocrystals and a plurality of organic ligands surrounding them can be prepared.

On the other hand, the size of the organic-inorganic perovskite nanocrystals produced in this way is preferably 20 nm to 30 nm in a range equal to or greater than the bore diameter beyond the quantum confinement effect. If the size of organic/inorganic perovskite nanocrystals exceeds 30 nm, thermal ionization and delocalization of charge carriers in the large nanocrystals cause excitons not to emit light and are separated into free charges and disappear. There may be.

In addition, in the case of nanocrystal particles having a size of less than the bore diameter, that is, less than 20 nm, the band gap changes depending on the particle size. In the case of nanocrystal particles of less than 20 nm in size, it is difficult to control the size as the size decreases. , color purity and spectrum are affected by the size, and there may be a disadvantage that the efficiency is rather reduced due to defects on the surface of the nanocrystal.

The resulting organic-inorganic hybrid perovskite quantum dots may exhibit strong fluorescence due to crystallization.

The resulting organic-inorganic hybrid perovskite quantum dot colloidal solution may be additionally quenched to avoid side reactions.

Next, in step S300, methyl acetate is added as a washing solvent to the second solution, centrifuged, and redispersed in an organic solvent to stabilize organic-inorganic hybrid perovskite nanocrystals by binding acetate anions to the surface of organic-inorganic hybrid perovskite nanocrystals. This is the step of forming quantum dots.

Since the freshly synthesized organic-inorganic hybrid perovskite quantum dots contain certain impurities (eg, Pb ²⁺ , MA ⁺ , Br ^- , and unbound ligands, etc.), the washing process is performed to obtain high-purity perovskite essential to obtain quantum dots.

However, polar solvents such as acetone and methanol, which are mainly used to precipitate metal chalcogenide perovskite quantum dots, such as CdS, CdSe, PbS, PbSe and AgBiS ₂ , etc., as conventional washing solvents, are organic-inorganic hybrid perovskite There was a problem that could cause serious damage to the core and surface of the organic-inorganic hybrid perovskite quantum dot by breaking down the weak ionic bond between the organic cations in the quantum dot and the metal halide octahedron.

Therefore, finding an appropriate cleaning solvent that does not damage organic-inorganic hybrid perovskite quantum dots has become an urgent task.

Accordingly, the present inventors performed a washing process using various solvents in order to find an appropriate washing solvent that does not damage the organic-inorganic hybrid perovskite quantum dots. As a result, no adverse effect occurred when washing using methyl acetate as a washing solvent, As a result, it was confirmed that the organic-inorganic hybrid perovskite quantum dots exhibited a high production rate and excellent long-term stability with respect to their optical properties, colloidal dispersion, and crystallinity.

Therefore, it is preferable to use methyl acetate for cleaning the organic-inorganic hybrid perovskite quantum dots according to the present invention.

3 is a reaction between the surface of the organic-inorganic hybrid perovskite quantum dots and methyl acetate during the washing process using methyl acetate as a cleaning solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention It is a schematic diagram showing the mechanism.

Referring to FIG. 3, methyl acetate (MeOAc) molecules react with water molecules in the air and are hydrolyzed to form acetate (CH ₃ COO ^- ) anions, which are oleic acetate on the surface of the perovskite quantum dots. While partially replacing the ligand, it stabilizes the surface of the perovskite quantum dot by strongly ionic bonding to the surface of the perovskite quantum dot.

At this time, the volume ratio of the second solution containing the freshly synthesized perovskite quantum dots to methyl acetate (MeOAc) may be mixed at a ratio of 1:1 to 1:5, specifically 1:3. Organic-inorganic hybrid perovskite quantum dots exhibiting long-term stability within the above range can be produced at a high production rate.

After the washing process, only organic-inorganic hybrid perovskite quantum dots purified through centrifugation may be recovered and redispersed in an organic solvent for use.

As the organic solvent, solvents commonly used in the art, such as hexane, toluene, and chlorobenzene, may be used.

The redispersed organic-inorganic hybrid perovskite quantum dot solution may be further filtered through a filter.

The organic-inorganic hybrid perovskite quantum dots thus prepared had a stable cubic crystal structure, and exhibited excellent long-term stability by uniformly maintaining their crystal structure and size for about 5 months in a solution state (see FIGS. 8 to 10). ).

Color filter containing organic/inorganic hybrid perovskite quantum dots

In addition, another aspect of the present invention provides a color filter including organic-inorganic hybrid perovskite quantum dots having improved stability.

4 is a cross-sectional view schematically illustrating a color filter according to an embodiment of the present invention.

Referring to FIG. 4, the color filter 200 according to the present invention includes organic-inorganic hybrid perovskite quantum dots 100 having improved stability and a thermoplastic elastomer 110 in which the perovskite quantum dots 100 are dispersed. can do.

Since the perovskite quantum dots 100 are as described above, detailed descriptions are omitted to avoid redundant description.

The perovskite quantum dots 100 may be dispersed in the thermoplastic elastomer 110 . Accordingly, the color filter according to the present invention may have elasticity.

Specifically, the color filter according to the present invention may be in the form of a film formed by dispersing the perovskite quantum dots 100 in the thermoplastic elastomer 110 .

The thermoplastic elastomer 110 may include, for example, polyolefin, polysiloxane, polychloroprene, and polysulfide.

In this case, examples of the polyolefin elastomer may include polyisoprene, polyisobutylene, polybutadiene, and poly(cyclooctadiene).

Examples of polysiloxane elastomers may include poly(dimethylsiloxane), poly(methylsiloxane), partially alkylated poly(methylsiloxane), poly(alkyl methylsiloxane), and poly(phenylmethylsiloxane).

In addition, the thermoplastic elastomer 110 may include a copolymer elastomer, and examples of the copolymer elastomer may include a polyolefin copolymer elastomer and a fluorocarbon elastomer. Examples of polyolefin copolymer elastomers contain monomer units derived from ethylene, propylene, isoprene, isobutylene, butadiene and other dienes and contain monomer units derived from non-olefins such as acrylates, alkylacrylates and acrylonitrile. It may contain copolymers capable of

Specific examples of polyolefin copolymer elastomers are ethylene-propylene-diene copolymer (EPDM), butadiene-acrylonitrile copolymer (nitrile rubber, NBR), isobutylene-isoprene copolymer (butyl rubber) and ethylene-acrylates. may contain copolymers.

Examples of the fluorocarbon elastomer may include copolymers containing monomeric units derived from hexafluoropropylene, tetrafluoroethylene, and perfluoromethylvinyl ether.

Examples of elastic block copolymers may include acrylonitrile block copolymers, polystyrene block copolymers, polyolefin copolymers, polyester copolymers, polyamide copolymers, and polyurethane copolymers.

Examples of acrylonitrile elastomeric copolymers may include styrene-acrylonitrile (SAN) and acrylonitrile-styrene-acrylate.

Examples of polystyrene elastomeric copolymer polymers may include polystyrene, poly(methylstyrene) or polyolefin elastomers, polyolefin elastomeric copolymers, polysiloxanes or copolymers of poly(alkylacrylates) with other substituted polystyrenes. A specific example may include a styrene-butadiene copolymer (SBR).

Examples of polyurethane elastomeric copolymers may include copolymers of polyurethane with polyether or polyester.

Examples of elastomers may include mixtures of polypropylene and polyolefin elastomers, polyolefin copolymers. In addition, examples of the elastomer may include a mixture of butadiene-acrylonitrile copolymer elastomer (NBR) and polyamide or poly(vinyl chloride). Also, examples of the elastomer may include a mixture of polysiloxane elastomer and polyester or polyamide. Examples of elastomeric copolymers may include mixtures of polyacrylates with polyolefins or mixtures with block copolymer elastomers containing blocks of polyurethane, polyamide or polyester.

An example of the elastomer may be polystyrene-block-polyisoprene-block-polystyrene (SIS) represented by Formula 2 below.

[Formula 2]

(In Formula 2,

x, y and z are each an integer greater than or equal to 1;

The number average molecular weight (Mn) of Formula 2 is 1,000 to 1,000,000.)

The styrene content in the compound of Formula 2 may be 10 to 25 wt.%, but is not limited thereto.

The molecular weight and styrene content of the SIS elastomer can be controlled to adjust physical properties such as ductility, elasticity, brittleness, and strength as desired. For example, in one embodiment of the present invention (Formula 2a), Mn 1,900; Styrene content 17 wt. % SIS was used, but is not limited thereto.

The elastomer is not limited to the elastomers described above, and the elastomer matrix may include one or more types of elastomers to form an elastomer network.

The thermoplastic elastomer 110 may be capable of self-healing by having self-restoring ability from scratches and damage.

Stretchability of the thermoplastic elastomer 110 may be 5% or more along the tensile direction. Specifically, it may be 10% or more, such as 20% or more, more specifically 30% or more, such as 50% or more, and more preferably 100% or more. Accordingly, the color filter 200 according to the present invention is not broken by the applied strain and can be stretched by 5% or more, and typically can be stretched by 20% or more.

A method for manufacturing a color filter according to an embodiment of the present invention

Preparing a perovskite-elastomer composite dispersion by adding and mixing the organic-inorganic hybrid perovskite quantum dots and the elastomer having improved stability in a non-polar solvent; and

Forming a color filter in the form of a film by applying the perovskite-elastomer composite dispersion on a substrate and drying the dispersion may be included.

Non-polar solvents used to prepare the dispersion of the perovskite elastomer composite include alkanes such as butane, hexane, octane, and cyclohexane; aromatic compounds including toluene, chlorobenzene, and dichlorobenzene; Halogen compounds such as chloroform, dichloroethane, and dichloroethene may be used alone or in combination, but are not limited thereto.

The elastic body used in the present invention preserves the crystal structure of the perovskite quantum dots when forming a complex with the organic-inorganic hybrid perovskite quantum dots, maintains its optical properties, and has self-healing properties and stretchability.

Next, in the step of applying the perovskite-elastomer composite dispersion on the substrate, the substrate may be a glass substrate or a polymer substrate, but is not limited thereto. As the glass substrate, in particular, soda lime glass, glass containing barium or strontium, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass or quartz can be used. Further, examples of the polymer substrate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone substrates.

At this time, the coating may be performed by a known wet coating method using a coating device such as a roll coater, a spin coater, a slit and spin coater, a slit coater (sometimes referred to as a die coater), or an inkjet to obtain a desired thickness. .

Drying may be performed by natural drying or by heating with an oven, hot plate or the like. At this time, the heating temperature and heating time in the drying step are appropriately selected according to the solvent used, and may be performed at a temperature of 80 to 150 ° C for 1 to 30 minutes.

The color filter manufactured in this way is a composite film of perovskite quantum dots and an elastic body, and exhibits self-healing properties and elasticity at the same time, so it can be applied to a wearable display device by layering with a stretchable blue light emitting body to realize a pixel through patterning. can In addition, it can be used as an optical filter for a camera that requires a color filter. It can be manufactured by a deposition method such as an inkjet printing method. It can be applied to electronic skin, robots, wearable devices, and displays related to the 4th industry that can be used offline. In addition, it can be used in fields such as lasers, projectors, lighting, energy conversion devices, optical sensors, and biomarkers. It can be used as a wearable display for people or robots that need to be active, and it can be applied to areas where the volume or length changes because it is flexible. The device itself can restore its original optical properties without the need to repair or replace broken or cracked displays. Going further than the foldable display, it is possible to manufacture new types of products with stretchable and self-healing displays, and it is possible to secure competitiveness that can create new growth engines. It is possible to create a new growth engine by developing nanomaterial technology applicable to new industries such as next-generation new construction and self-healing displays. It is possible to enter not only the existing display industry, but also laser, projector, electronic skin, robot, wearable device, and display fields related to the 4th industry that can be used offline.

Hereinafter, preferred manufacturing examples and experimental examples are presented to aid understanding of the present invention. However, the following Preparation Examples and Experimental Examples are only for helping understanding of the present invention, and the present invention is not limited by the following Preparation Examples.

Organic-inorganic hybrid MAPbBr ₃ Preparation of perovskite quantum dots: Preparation Examples 1 to 4, Comparative Examples 1 to 4

<Preparation Example 1: Preparation of organic-inorganic hybrid MAPbBr ₃ perovskite quantum dots using methyl acetate>

After dissolving PbBr ₂ (0.4 mmol), CH ₃ NH ₃ Br (0.32 mmol), oleylamine (0.1 ml), and oleic acid (1 ml), which are precursor solutions of MAPbBr ₃ perovskite quantum dots, in DMF (10 ml). It was stirred using ultrasonic waves for 10 minutes. Toluene (10 ml) was maintained at 50 °C. Subsequently, the MAPbBr ₃ (1 ml) precursor solution was quickly injected into a glass bottle containing toluene while vigorously stirring, to induce colloidal crystallization of MAPbBr ₃ perovskite quantum dots. Strong fluorescence could be observed with the naked eye, and the synthesized colloidal solution was quenched to avoid side reactions.

Next, methyl acetate as a washing solvent was added to the synthesized MAPbBr ₃ perovskite quantum dot colloidal solution in a volume ratio of 1:1, and then the mixture solution was centrifuged at 8,000 rpm for 5 minutes. After discarding the supernatant, the precipitated perovskite quantum dots were redispersed in hexane and the final solution was filtered through a 0.2 μm PTFE filter to prepare stable MAPbBr ₃ perovskite quantum dots.

<Production Example 2>

Stable MAPbBr ₃ perovskite quantum dots were prepared by using methyl acetate as a washing solvent in a volume ratio of 1:3 in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1.

<Production Example 3>

Stable MAPbBr ₃ perovskite quantum dots were prepared by using methyl acetate as a washing solvent in a volume ratio of 1:5 in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1.

<Production Example 4>

Stable MAPbBr ₃ perovskite quantum dots were prepared by using methyl acetate as a washing solvent in a volume ratio of 1:7 in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1.

<Comparative Example 1>

After centrifugation without using any washing solvent in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1, the precipitated perovskite quantum dots were redispersed in hexane and the final solution was passed through a 0.2 μm PTFE filter. By filtration, MAPbBr ₃ perovskite quantum dots were prepared.

<Comparative Example 2>

Methanol was used as a washing solvent in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1 at a volume ratio of 1:1, and after centrifugation, the precipitated perovskite quantum dots were redispersed in hexane and the final solution was 0.2 MAPbBr ₃ perovskite quantum dots were prepared by filtering through a μm PTFE filter.

<Comparative Example 3>

Acetone was used as a washing solvent in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1 at a volume ratio of 1:1, and after centrifugation, the precipitated perovskite quantum dots were redispersed in hexane and the final solution was 0.2 MAPbBr ₃ perovskite quantum dots were prepared by filtering through a μm PTFE filter.

<Comparative Example 4>

Ethyl acetate was used as a washing solvent in the MAPbBr ₃ perovskite quantum dot colloidal solution synthesized in Preparation Example 1 at a volume ratio of 1: 1, then centrifuged, and the precipitated perovskite quantum dots were redispersed in hexane and the final solution was MAPbBr ₃ perovskite quantum dots were prepared by filtering through a 0.2 μm PTFE filter.

Experimental example

<Experimental Example 1: Effect of Washing Solvent on Production Yield of Organic-Inorganic Hybrid Perovskite Quantum Dots>

Since the freshly synthesized organic-inorganic hybrid perovskite quantum dots contain certain impurities (eg, Pb ²⁺ , MA ⁺ , Br ^- , and unbound ligands, etc.), the washing process is performed to obtain high-purity perovskite essential to obtain quantum dots. Acetone and methanol (MeOH) are non-solvents mainly used to precipitate various metal chalcogenide perovskite quantum dots, such as CdS, CdSe, PbS, PbSe and AgBiS ₂ . However, these polar solvents can cause serious damage to the core and surface of organic-inorganic hybrid perovskite quantum dots, which is due to weak ionic bonds between organic cations and metal halide octahedra in organic-inorganic hybrid perovskite quantum dots. Because. Therefore, finding an appropriate cleaning solvent that does not damage organic-inorganic hybrid perovskite quantum dots has become an urgent task.

Therefore, in order to find an appropriate washing solvent that does not damage the organic-inorganic hybrid perovskite quantum dots, no washing solvent is used in the freshly synthesized MAPbBr ₃ perovskite quantum dot colloidal solution in Preparation Example 1 (Comparative Example 1, hereinafter Neat), ₃ pages of MAPbBr produced after purification using methyl acetate (Preparation Example 1), methanol (Comparative Example 2), acetone (Comparative Example 3) or ethyl acetate (Comparative Example 4) as washing solvents. Production yield and UV-vis absorbance of the lobesite quantum dots were measured and shown in FIG. 5 .

Figure 5 shows (a) production yield, and (b) of perovskite quantum dots prepared according to the washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention. Indicates UV absorbance.

As shown in FIG. 5, when no washing solvent was used (Neat) according to Comparative Example 1, only a small amount (about 30%) of precipitate was obtained, and almost no absorbance was obtained.

In the case of using highly polar methanol or acetone as the washing solvent, the production yield after purification was normalized to less than 40%, which _was very low. The methylammonium substituent is easily dissolved through a hydrogen bonding reaction, and the partially anionic oxygen atom in acetone also reacts strongly with Pb ²⁺ on the surface of these perovskite quantum dots, resulting in the octahedral structure of the perovskite quantum dots. It is thought that this is because it can be broken down. Even in the absorbance analysis, the absorption intensity was equal to or lower than that of the case where no washing solvent was used (Neat).

In addition, when ethyl acetate (EtOAc) was used as the washing solvent, production yield and absorbance increased compared to methanol and acetone, but production yield and absorbance were lower than when methyl acetate (MeOAc) was used.

Therefore, when preparing organic-inorganic hybrid quantum dots, the selection of the washing solvent is important, and when methyl acetate is used as the washing solvent according to the present invention, the production yield and absorbance of the organic-inorganic hybrid quantum dots produced by purification are compared to other solvents. It was confirmed that it was markedly higher than that.

<Experimental Example 2: Effect of Washing Solvent on Optical Stability of Organic-Inorganic Hybrid Perovskite Quantum Dots>

In the preparation of the organic-inorganic hybrid perovskite quantum dots according to the present invention, the following experiment was performed to determine the stability of the organic-inorganic perovskite quantum dots in a washing solvent.

Specifically, the MAPbBr ₃ perovskite quantum dot colloidal solution freshly synthesized in Preparation Example 1 did not use a washing solvent (Comparative Example 1, hereinafter referred to as Neat), or as a washing solvent, methyl acetate (Preparation Example 1), methanol ( Comparative Example 2) or acetone (Comparative Example 3) was added and mixed at a volume ratio of 1: 1, and then the MAPbBr ₃ perovskite quantum dot solution was immediately stored and stored for 3 months, then exposed to UV light to observe the luminescence state. shown in Figure 6.

Figure 6 is in the production of organic-inorganic hybrid perovskite quantum dots according to one embodiment and one comparative example of the present invention, the optical properties of the perovskite quantum dots prepared according to the washing solvent under UV light and the optical properties after 3 months represents a characteristic.

As shown in FIG. 6, after mixing the freshly synthesized MAPbBr ₃ perovskite quantum dot colloidal solution with methanol, the PL emission of the perovskite quantum dots under UV light exposure soon disappeared in a few seconds, and the yellow lead compound ( lead compound) completely disappeared after 3 months. Perovskite quantum dots mixed with acetone also significantly weakened PL emission within a few minutes after mixing, and a significant amount of the yellow lead compound disappeared after 3 months. These results imply that organic-inorganic hybrid perovskite quantum dots are mostly or gradually dissolved in methanol and acetone.

In contrast, after mixing with methyl acetate as a washing solvent according to the present invention, there was no significant change in PL emission and physical appearance of organic-inorganic hybrid perovskite quantum dots, and their emission characteristics remained stable even after 3 months. These results suggest that methyl acetate does not decompose organic-inorganic hybrid perovskite nanocrystals, and therefore, the method according to the present invention uses methyl acetate as a washing solvent, and thus has excellent solution stability and a time of 3 months or more. Organic-inorganic hybrid perovskite quantum dots having stable light emitting properties even after passing can be prepared with high production yield.

<Experimental Example 3: Reaction Mechanism of Organic-Inorganic Hybrid Perovskite Quantum Dot Surface in the Presence of Methyl Acetate (MeOAc) and Moisture (H ₂ O)>

In the organic-inorganic hybrid perovskite quantum dot production according to the present invention, FTIR analysis was performed to investigate the reaction mechanism of the organic-inorganic hybrid perovskite quantum dot surface when methyl acetate was used as a washing solvent.

Specifically, purification was performed by adding methyl acetate at a volume ratio of 1:0, 1:1, 1:3, 1:5, and 1:7 to the MAPbBr ₃ perovskite quantum dot colloidal solution freshly synthesized in Preparation Example 1. FTIR analysis was performed by preparing organic-inorganic hybrid perovskite quantum dot samples (hereinafter referred to as Neat, MeOAc_1, MeOAc_3, MeOAc_5, and MeOAc_7, respectively). In addition, for comparison, FTIR analysis was also performed on methyl acetate, oleylamine, and oleic acid in the pure solvent state, and the results are shown in FIG. 7 .

Figure 7 is in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention, (a) perovskite quantum dots (Neat) without using a washing solvent and as a washing solvent FTIR spectra of perovskite quantum dots (MeOAc_1 to MeOAc_7) prepared using various ratios of methyl acetate, methyl acetate, oleylamine, and oleic acid in pure solvents, and (b) an enlarged view of specific peaks thereof indicates

The spectrum of the perovskite quantum dot powder shows the organic part of the perovskite quantum dot core (i.e., within MAPbBr ₃ ). CH ₃ NH ₃ ⁺ ) and peaks generated by stretching and bending vibrations of functional groups in organic ligand molecules. In this case, the perovskite quantum dot powder may include five organic ligand molecules such as acetate, oleate, oleylammonium, oleic acid, and oleylamine.

Here, since oleate, oleylammonium, oleic acid and oleylamine molecules share oleyl resonances ( ν (CH _x ) = 2780-3000 cm ^-1 and ν (C=CH) = 3006 cm ^-1 ), FTIR spectra were normalized for oleyl resonance peak intensities for Neat and MeOAc_1 to MeOAc_7 samples.

Then, as the volume ratio of freshly synthesized perovskite quantum dots to methyl acetate increases from 1:0 to 1:7, ammonium ( ν (-NH ₃ ⁺ ) = 3100-3300 cm ^-1 ), carbonyl of carboxylic acid ( ν (C=O) = 1710 cm ⁻¹ ), and relative changes to resonance peak intensities associated with asymmetric carboxylates ( ν as(COO ⁻ ) = 1581 cm ⁻¹ ) were investigated.

At this time, the oleate ligands attached to the MAPbBr ₃ perovskite quantum dots can be distinguished from unbonded oleic acid by carboxylate resonance ( ν as(COO ⁻¹ ) = 1581 cm ⁻¹ ). Moreover, only unbonded oleic acids have the carbonyl stretching vibration of carboxylic acids ( ν (C=O) = 1710 cm ^-1 ).

Thus, as shown in FIG. 7, the presence of bound oleate ligands and unbound oleic acid can be obtained from the ν _as (COO ⁻ ) = 1581 cm ⁻¹ and ν (C=O) = 1710 cm ⁻¹ vibrations, respectively. Confirmed. In addition, the perovskite quantum dot sample was confirmed to have an ammonium resonance ( ν (-NH ₃ ⁺ ) = 3100-3300 cm ^-1 ). Since pure oleylamine did not show a peak in the 3100-3300 cm ^-1 band, the ammonium resonance ( ν (-NH ₃ ⁺ ) = 3100-3300 cm ^-1 ) of this perovskite quantum dot sample was MAPbBr ₃ perovskite. It can be seen that this is probably due to the oleinammonium ligand combined with methyl ammonium (CH ₃ NH ₃ ⁺ ) in the skyte quantum dot core.

In addition, as the volume ratio of the freshly synthesized perovskite quantum dot solution to methyl acetate (MeOAc) increased from 1:0 to 1:7, the relative peak intensities of ν _as (COO ^- ) and ν (-NH ₃ ⁺ ) also increased. This suggests that the number of functional linking groups of NH ₃ ⁺ and COO ⁻ increased relatively compared to long hydrocarbon chains.

From these results, as shown in FIG. 3, it can be seen that deprotonated acetic acid formed by hydrolysis of methyl acetate (MeOAc) molecules partially replaces oleic acetate ligands on the surface of the perovskite quantum dots. .

The increases in the relative peak intensities of ν _as (COO ^- ) and ν (-NH ₃ ⁺ ) saturate in the smallest amount of MeOAc (ie, MeOAc_1), and further increases in the volume of MeOAc contribute to the increase in relative peak intensities. Didn't have enough impact to consider. This saturation will be due to the limited amount of water molecules in the air in the centrifuge tube, which can control the hydrolysis reaction.

Unlike the relative peak intensities of ν _as (COO ^- ) and ν (NH ₃ ⁺ ), the carbonyl stretching vibration of carboxylic acid ( ν (C=O)) gradually decreased with the increase in the volume of MeOAc. suggest that a higher volume of MeOAc in the washing step of the perovskite quantum dots removed a higher amount of unbound organic residues, such as oleic acid.

<Experimental Example 4: Crystallinity measurement of organic-inorganic hybrid perovskite quantum dots washed with methyl acetate according to the present invention>

In order to examine the crystalline characteristics of organic-inorganic hybrid perovskite quantum dots washed with methyl acetate according to the present invention, powder XRD analysis of Neat and MeOAc_1 to MeOAc_7 samples was performed and shown in FIG. 8 .

8 is a perovskite quantum dot (Neat) without using a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment and a comparative example of the present invention, and various ratios as a washing solvent X-ray diffraction spectra of perovskite quantum dots (MeOAc_1 to MeOAc_7) freshly prepared using methyl acetate and perovskite quantum dots after 5 months (5 months) are shown.

As shown in Fig. 8, all samples exhibited the same XRD pattern with peaks at 14.92 °, 21.16 °, 30.12 °, 33.78 °, 43.1 °, and 45.88 °, respectively, for a cubic lattice (100), (110), (200), (210), (220), and (300) planes.

These XRD patterns and crystal structures were consistent with previously reported MAPbBr ₃ perovskite quantum dots, confirming that MAPbBr ₃ perovskite quantum dots were successfully fabricated according to the present invention.

Here, the dominant intensities of the (100) and (200) planes indicate that most MAPbBr ₃ perovskite QD crystals have a cubic Pm3m symmetric space group and do not contain an asymmetric P4mm space group.

For the (100) and (200) plane peaks, the full width at half maximum (FWHM) of these two peaks was almost similar in MeOAc_1 to MeOAc_5 samples, but the full width at half maximum value of MeOAc_7 was slightly higher. These results were also consistent with UV-vis absorption analysis, and it can be seen from these results that excessive use of methyl acetate (MeOAc) in the washing process adversely affects the quality of MAPbBr ₃ perovskite quantum dots. Therefore, it was confirmed that the amount of methyl acetate added to the perovskite quantum dot colloidal solution in the washing process was preferably 1:1 to 1:5 in terms of volume ratio.

Nevertheless, no phase change of the crystal structure was observed for the MeOAc_1 to MeOAc_7 samples, which is likely because the cubic lattice structure is more stable than the rhombic MAPbBr ₃ , which is easily decomposed even at room temperature.

Therefore, in order to more specifically observe the crystal structure of the organic-inorganic hybrid perovskite quantum dots prepared according to the present invention, morphology analysis of the MeOAc_1 sample was performed using high-resolution TEM (HR-TEM), and FIGS. 9 and 10 shown in

9 shows (a) freshly prepared perovskite quantum dots and (b) 5 months using methyl acetate as a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention. This is a picture of the crystal structure of the perovskite quantum dot observed with a high-resolution transmission electron microscope.

10 shows (a) freshly prepared perovskite quantum dots and (b) 5 months using methyl acetate as a washing solvent in the production of organic-inorganic hybrid perovskite quantum dots according to an embodiment of the present invention. The particle size distribution of perovskite quantum dots after

As shown in FIGS. 9 and 10, the organic-inorganic hybrid perovskite quantum dots purified using methyl acetate as a washing solvent according to the present invention have a particle size of about 11 nm on average and have stable cubic crystals without significant aggregation. Observed.

The crystals exhibited moderate and uniform size. This observation is consistent with the PL spectrum. Noteworthy is that the cubic crystals of MAPbBr ₃ perovskite quantum dots showed excellent long-term stability in solution. The measured perovskite quantum dot solution was stored for 5 months, even exceeding 5 months, under a dark ambient environment (temperature: 20 ± 5 ° C; relative humidity 35% ± 15%), and the particle size and dispersion were almost the same. Morphological properties were shown. These results strongly suggest that methyl acetate can be efficient and effective in obtaining stable organic-inorganic hybrid perovskite quantum dots with high production yield.

Preparation of Self-Healing and Stretchable Color Filter Containing Organic-Inorganic Hybrid Perovskite Quantum Dots: Preparation Examples 5 to 8

<Production Example 5>

SIS (polystyrene-block-polyisoprene-block-polystyrene, Formula 2a) was dissolved in hexane (100 mg/ml) at 90 ° C., and the organic-inorganic hybrid perovskite quantum dot solution (about 0.1 ml) prepared in Preparation Example 1 ) was mixed with a SIS solution (1ml) at 90 °C to prepare a perovskite quantum dot-SIS composite solution.

Next, the perovskite quantum dot-SIS composite solution was coated on a glass substrate (2 × 2 cm ² ), and then the solution was evaporated to form a perovskite quantum dot-SIS composite film. A self-healing and stretchable green color filter in the form of a free-standing perovskite quantum dot-SIS composite film was prepared by separating the formed film from the glass substrate.

[Formula 2a]

(In Formula 2a,

x, y and z are each an integer greater than or equal to 1;

The number average molecular weight (Mn) is 1,900 and the styrene content is 17 wt.%.)

<Preparation Examples 6 to 8>

Self-healing in the form of a quantum dot-SIS composite film performed in the same manner as in Preparation Example 5, except that the organic-inorganic hybrid perovskite quantum dot solutions of Preparation Examples 2 to 4 were used for the organic-inorganic hybrid perovskite quantum dot solution. and a stretchable green color filter.

<Analysis>

1) Shape and emission characteristics of color filters

11 shows a color filter in the form of an organic-inorganic hybrid perovskite quantum dot-elastic composite film prepared according to an embodiment of the present invention and its optical properties under UV light.

As shown in FIG. 11, the color filter exhibits a composite film form of organic-inorganic hybrid perovskite quantum dots and an elastic body, and emits uniform green (MAPbBr ₃ ) fluorescence in UV light.

2) Stretching and self-healing characteristics of color filters

In order to confirm the stretchability and self-healing characteristics of the color filter prepared according to the present invention, the color filter prepared in Preparation Example 5 was stretched while irradiating UV light, or cut into two parts, and then the two split pieces were overlapped. , and applied pressure with a finger to the overlapped part to observe whether it was reattached. In addition, while extending the attached color filter, it was observed whether the attached portion was cut, and it is shown in FIG. 12 .

12 is a photograph showing stretch and self-healing characteristics of a color filter manufactured according to an embodiment of the present invention.

As shown in FIG. 12, the color filter prepared according to the present invention showed excellent elasticity properties by flexibly stretching without physical damage while exhibiting green fluorescence in UV light, and after cutting, the cut surface was overlapped and pressure was applied with a finger. By being attached, self-healing properties were exhibited. The attached portion exhibited green fluorescence in UV light while maintaining excellent elasticity without breaking at the coupling portion.

Meanwhile, in order to test the self-healing properties of the color filter prepared according to the present invention, two types of physical damage were applied by placing the color filter prepared in Preparation Example 5 on a glass substrate and scratching the surface of the color filter with a razor blade. 1) In the case of the first type, dotted traces appeared on the surface of the film due to shallow scratches. 2) For the second type, the film was cut into two parts to reveal deep scratches. While heating the damaged film at 100 ° C., changes in the surface state of the film were observed with an optical microscope and are shown in FIGS. 13 and 14 .

13 is an optical micrograph showing before and after self-healing of shallow and deep scratches of a color filter manufactured according to an embodiment of the present invention.

14 shows cross-sectional height profiles of flaws before and after self-healing of deep flaws on a color filter manufactured according to an embodiment of the present invention.

As shown in FIGS. 13 and 14, the surface of the color filter manufactured according to the present invention was completely healed when there was a shallow scratch, and even in the case of a color filter with a deep scratch of about 2 μm above and below, the color filter A few traces of scars were left on the surface of the film, but it was almost completely restored to its original shape after healing.

Therefore, since the color filter according to the present invention has excellent stretch and self-healing properties, it can be usefully used for flexible/foldable displays.

Preparation of white LED device: Preparation Examples 9 to 12

A green color filter in the form of a MAPbBr ₃ -SIS composite film prepared in Preparation Examples 5 to 8 and a CsPbBr _0.6 I _2.4 perovskite quantum dot-SIS composite film (red color filter) were sequentially laminated on an InGaN blue LED chip to produce white An LED device was manufactured (see the inset of FIG. 15).

The color temperature of the white LED can be adjusted by controlling the blue LED chip power intensity and the concentration of perovskite quantum dots in the color filter.

<Analysis>

1) Emission spectrum of LED device

15 shows an emission spectrum of an LED device manufactured according to an embodiment of the present invention.

As shown in FIG. 15, in the LED device manufactured according to the present invention, no particular change in emission spectrum occurred during driving of the device. Through this, it can be confirmed that the organic-inorganic hybrid perovskite quantum dots prepared according to the present invention have stability against migration of halide ions in the composite.

2) Color coordinates of LED elements

16 shows CIE color coordinates of an LED device manufactured according to an embodiment of the present invention. Here, for the relative comparison of color gamut, Rec. 2020 and the color coordinates in the National Television System Committee (NTSC) standard are shown together.

Referring to FIG. 16, the color coordinates of the fabricated white LED device are (red; 0.678, 0.301), (green; 0.173, 0.771) and (blue; 0.153, 0.024), indicating the CIE of the LED device according to the present invention. The color coordinate triangle occupied 109% of the NTSC standard and showed a 95% overlap with the Rec.2020 space, confirming that it exhibits excellent color gamut.

Therefore, the white LED device including the color filter according to the present invention exhibits stable light emission, has a wide color gamut, and exhibits excellent color reproducibility, so that it can be usefully used instead of the conventional white LED device.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those skilled in the art to which the present invention pertains may take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

100: organic-inorganic hybrid perovskite quantum dots according to the present invention
110: elastic body
200: organic-inorganic hybrid perovskite quantum dot-elastic composite color filter according to the present invention

Claims (17)

preparing a first solution by dissolving organic/inorganic hybrid perovskite precursors and an organic ligand in a protic solvent;
mixing the first solution with an aprotic solvent to form a second solution in which organic-inorganic hybrid perovskite quantum dots are formed; and
Purifying organic-inorganic hybrid perovskite quantum dots by adding methyl acetate as a washing solvent to the second solution and redispersing the precipitate in an organic solvent after centrifugation
Purification method of organic-inorganic hybrid perovskite quantum dots. According to claim 1,
Refined organic-inorganic hybrid perovskite quantum dots
organic-inorganic hybrid perovskite nanocrystals dispersed in an organic solvent; and
Including a plurality of ligands surrounding the organic-inorganic hybrid perovskite nanocrystal,
At least one of the ligands is an acetate anion (CH ₃ COO ^- ) Purification method of organic-inorganic hybrid perovskite quantum dots, characterized in that. According to claim 2,
The organic-inorganic hybrid perovskite nanocrystal is a method for purifying organic-inorganic hybrid perovskite quantum dots, characterized in that it comprises a structure of formula (1).
[Formula 1]
ABX ₃
(In Formula 1 above,
Wherein A is organoammonium,
Wherein B is a metal material,
The X is a halogen element.) According to claim 3,
A is methylammonium, formammonium, guanidinium, (CH(NH ₂ ) ₂ , C _x H _2x+1 (CNH ₃ ), (CH ₃ NH ₃ ) _n , ((C _x H _2x+1 ) _n NH ₃ ) _n (CH ₃ NH ₃ ) _n , R(NH ₂ ) ₂ (Where R=alkyl), (C _n H _2n+1 NH ₃ ) _n , (CF ₃ NH ₃ ), (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) _n , (C _n F _2n+1 NH ₃ ) _n (where n and x are integers from 1 to 100) or a derivative thereof;
Wherein B is Pb, Mn, Cu, Ga, Ge, In, Al, Sb, Bi, Po, Sn, Eu, Yb, Ni, Co, Fe, Cr, Pd, Cd, Ca, Sr, or combinations thereof;
Wherein X is Cl, Br, I or a combination thereof. According to claim 2,
Among the ligands, the remaining ligands except for the acetate anion (CH ₃ COO ^- ) are selected from the group consisting of amine ligands, organic acids, phosphine ligands, sulfide ligands, secondary ligands (bidentate) ligands, and tridentate ligands. Purification method of organic-inorganic hybrid perovskite quantum dots. According to claim 2,
Among the ligands, the ligands other than the acetate anion (CH ₃ COO ^- ) are hexylamine, octylamine, decylamine, dodecylamine, oleylamine, and hexanoic. Hexanoic acid, octanoic acid, decanoic acid, undecanoic acid, lauric acid, hexadecanoic acid, Octadecanoic acid, oleic acid, trioctylphosphine, trioctylphosphine oxide, 1,2-ethanedithiol and 3- (N, N-dimethyloctadecylammonio) a method for purifying organic-inorganic hybrid perovskite quantum dots, characterized in that selected from the group consisting of propanesulfonate. According to claim 2,
The acetate anion (CH ₃ COO ^- ) Purification method of organic-inorganic hybrid perovskite quantum dots, characterized in that for stabilizing the perovskite quantum dots by ionic bonding to the surface of the purified organic-inorganic hybrid perovskite quantum dots. According to claim 2,
The purified organic-inorganic hybrid perovskite quantum dots are purified method of organic-inorganic hybrid perovskite quantum dots, characterized in that having a cubic crystal structure. According to claim 2,
The purification method of organic-inorganic hybrid perovskite quantum dots, characterized in that the average particle size of the purified organic-inorganic hybrid perovskite quantum dots is 1 nm to 100 nm. According to claim 1,
When methyl acetate is added to the second solution, the volume ratio of the second solution to methyl acetate is 1: 1 to 1: 5. Method for purifying organic-inorganic hybrid perovskite quantum dots. Organic-inorganic hybrid perovskite quantum dots purified in claim 1; and
A color filter comprising a thermoplastic elastomer in which the organic-inorganic hybrid perovskite quantum dots are dispersed. According to claim 11,
The color filter is a color filter, characterized in that in the form of a film formed by dispersing purified organic-inorganic hybrid perovskite quantum dots in a thermoplastic elastomer. According to claim 11 or 12,
The thermoplastic elastomer is polyolefin, polysiloxane, polychloroprene, polysulfide, polyolefin copolymer elastomer, fluorocarbon elastomer, acrylonitrile block copolymer, polystyrene block copolymer, polyolefin copolymer, polyester copolymer, polyamide copolymer and A color filter characterized in that it is selected from the group consisting of polyurethane copolymers. According to claim 13,
The color filter, characterized in that the thermoplastic elastomer is polystyrene-block-polyisoprene-block-polystyrene (SIS) represented by Formula 2 below.
[Formula 2]

(In Formula 2,
x, y and z are each an integer greater than or equal to 1;
The number average molecular weight (Mn) of Formula 2 is 1,000 to 1,000,000,
The styrene content in the compound of Formula 2 is 10 to 25 wt.%.) According to claim 11,
The color filter is characterized in that the color filter has elasticity and self-healing ability by having self-restoring ability by scratch and damage. Preparing a perovskite-elastomer composite dispersion by adding and mixing the organic-inorganic hybrid perovskite quantum dots and the elastomer purified in claim 1 in a non-polar solvent; and
A method of manufacturing a color filter comprising the step of applying the perovskite-elastomer composite dispersion on a substrate and drying it to form a color filter in the form of a film. According to claim 16,
The non-polar solvent is an alkane selected from the group consisting of butane, hexane, octane and cyclohexane; an aromatic compound selected from the group consisting of toluene, chlorobenzene and dichlorobenzene; and a halogen compound selected from the group consisting of chloroform, dichloroethane, and dichloroethene, or a mixed solvent thereof.

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