KR102563058B1 - A quantum dot, a quantum dot light-emitting diode and a quantum dot film and a light converting resin composition comprising the quantum dot, a color filter and a light converting laminated base material manufactured by the composition and a display device comprising the same - Google Patents

Abstract

The present invention is a quantum dot having a ligand layer on its surface, characterized in that the ligand layer includes the compound represented by Formula 1, a quantum dot light emitting diode including the same, a quantum dot film, a light conversion resin composition, and the light conversion Provided is a color filter formed using a resin composition, a light conversion laminated base material, and an image display device including the color filter or the light conversion laminated base material.

Description

Quantum dot, quantum dot light emitting diode including the same, quantum dot film, light conversion resin composition, color filter formed using the light conversion resin composition, light conversion laminated base material, and image display device including the color filter or the light conversion laminated base material {A QUANTUM DOT, A QUANTUM DOT LIGHT-EMITTING DIODE AND A QUANTUM DOT FILM AND A LIGHT CONVERTING RESIN COMPOSITION COMPRISING THE QUANTUM DOT, A COLOR FILTER AND A LIGHT CONVERTING LAMINATED BASE MATERIAL MANUFACTURED BY THE COMPOSITION AND A DISPLAY DEVICE COMPRISING THE SAME}

The present invention provides a quantum dot, a quantum dot light emitting diode including the same, a quantum dot film, a light conversion resin composition, a color filter formed using the light conversion resin composition, a light conversion laminated base material, and the color filter or the light conversion laminated base material. It relates to an image display device.

Quantum dots have high luminescence and a narrow luminescence spectrum, can control the luminescence wavelength with one excitation wavelength, and have the inherent characteristics of quantum dots that are stable against light. A lot of research has been done to use it in the same important application field.

These quantum dots are materials that are very sensitive to the surface state, and oxidation occurs from the surface depending on the solvent or surrounding environment in which they are dispersed, resulting in a sharp decrease in luminous efficiency. For various applications of quantum dots, they must be dispersed in various solvents other than the organic solvent in which they were originally dispersed or must form specific functional groups on the surface. These processes damage the surface of quantum dots and eventually lead to a decrease in luminous efficiency. there is

Many attempts have been made to overcome these problems, and various methods are currently being proposed. One of them is a functional group substitution (ligand exchange) method in which organic materials present on the surface of quantum dots are replaced with molecules having a desired functional group. This method is a method of substituting organic molecules present on the surface of quantum dots with organic molecules suitable for application, but has a disadvantage of causing fatal problems in luminous efficiency because it directly affects the surface of quantum dots.

Korean Patent Publication No. 10-2018-0002716 and Korean Patent Registration No. 10-1628065 disclose quantum dots including ligands disposed on the surface, but have low compatibility, poor dispersibility to monomers, and stability and reliability. This is a situation that has not been able to solve the problem that the light resistance decreases with the passage of time.

Republic of Korea Patent Publication No. 10-2018-0002716 Republic of Korea Patent No. 10-1628065

The present invention is to improve the problems of the prior art described above, by including the compound represented by Formula 1 on the surface as a ligand layer, so that the surface of the quantum dots is protected to have excellent oxidation stability, and to prevent a decrease in quantum efficiency, Therefore, it is an object of the present invention to provide a quantum dot with improved reliability.

In addition, an object of the present invention is to provide a quantum dot film, a light conversion resin composition, and a quantum dot light-emitting diode (QLED) including the quantum dots.

In addition, an object of the present invention is to provide a color filter formed using the light conversion resin composition, a light conversion laminated base material, and an image display device including the color filter or the light conversion laminated base material.

The present invention is a quantum dot having a ligand layer on the surface,

The ligand layer provides a quantum dot including a compound represented by Formula 1 below.

[Formula 1]

In Formula 1,

A is a straight-chain or branched chain mercaptoalkyl group having 1 to 10 carbon atoms, a straight-chain or branched chain carboxyl group having 1 to 10 carbon atoms, or ego,

Wherein R is a direct bond or a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

In the above, R ₁ is a direct bond or a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

In the above, R ₂ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and

* represents a bonding hand,

n is an integer from 1 to 250;

In addition, the present invention provides a quantum dot light emitting diode, a quantum dot film, and a light conversion resin composition including the quantum dots.

In addition, the present invention provides a color filter formed using the light conversion resin composition, a light conversion laminated base material, and an image display device including the color filter or the light conversion laminated base material.

The quantum dot according to the present invention includes a compound represented by a specific chemical structure as a ligand layer, so that the surface of the quantum dot is protected to have excellent oxidation stability and to prevent a decrease in quantum efficiency.

Therefore, the quantum dots can provide an effect of improving quantum efficiency and reliability, and can be effectively applied to various applications such as quantum dot films, quantum dot light emitting diodes, color filters, and light conversion laminates.

Hereinafter, the present invention will be described in detail.

The present invention provides a quantum dot having a ligand layer on its surface, characterized in that the ligand layer includes a compound represented by Formula 1 below.

In the quantum dot of the present invention, by including a specific compound in the ligand layer, the surface of the quantum dot is protected to improve oxidation stability, prevent a decrease in quantum efficiency, and thus improve luminance and reliability.

In addition, the present invention provides a quantum dot light-emitting diode (QLED), a quantum dot film, or a light conversion resin composition including the quantum dots.

In addition, the present invention provides a color filter formed using the light conversion resin composition, a light conversion laminated base material, and an image display device including the color filter or the light conversion laminated base material.

Hereinafter, the configuration of the present invention will be described in detail.

<Quantum Dot>

In the present invention, quantum dots may be self-luminous by a light source and used to generate light in the visible and infrared regions. Quantum dots are materials with a crystal structure of several nanometers, and may be composed of hundreds to thousands of atoms. Atoms form molecules, and molecules form a collection of small molecules called clusters to form nanoparticles. Generally, when these nanoparticles have the characteristics of a semiconductor, they are called quantum dots, and the quantum dots of the present invention It is not particularly limited as long as it conforms to the concept. When an object becomes smaller than the nano size, a quantum confinement effect occurs, which is a phenomenon in which the energy band gap of the object increases. It emits energy corresponding to the gap and can emit light by itself.

The quantum dot according to the present invention is characterized in that it has a ligand layer on its surface, and the ligand layer includes a compound represented by Formula 1 below. Accordingly, the surface of the quantum dot is protected, and oxidation stability is improved, thereby preventing a decrease in quantum efficiency and improving reliability.

[Formula 1]

In Formula 1,

A is a straight-chain or branched chain mercaptoalkyl group having 1 to 10 carbon atoms, a straight-chain or branched chain carboxyl group having 1 to 10 carbon atoms, or ego,

Wherein R is a direct bond or a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

In the above, R ₁ is a direct bond or a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

In the above, R ₂ is hydrogen or an alkyl group having 1 to 10 carbon atoms,

* represents a bonding hand,

n is an integer from 1 to 250;

The compound represented by Formula 1 includes a hydroxyl group, an alkoxy group, a mercaptoalkyl group, a carboxyl group, and the like, and the hydroxyl group, alkoxy group, mercaptoalkyl group, and/or carboxyl group may be bonded to the surface of the quantum dot. Compared to conventional ligand layer compounds having quantum dots, the group has excellent bonding force with the surface of the quantum dots, thereby suppressing quenching due to surface defects such as dangling bonds of quantum dots and quenching due to surface oxidation, thereby improving light characteristics (light emitting characteristics) and reliability. There are advantages to improving.

In one embodiment of the present invention, the compound represented by Chemical Formula 1 may be a compound represented by any one of Chemical Formulas 1-1 to 1-5.

[Formula 1-1]

In Formula 1-1, n is an integer from 1 to 250.

[Formula 1-2]

In Formula 1-2, n is an integer from 1 to 250.

[Formula 1-3]

In Formula 1-3, n is an integer from 1 to 250.

[Formula 1-4]

In Chemical Formula 1-4, n is an integer from 1 to 250.

[Formula 1-5]

In Formula 1-5, n is an integer from 1 to 250.

In the present invention, unlike single molecules, chemical formulas having a range of n values in formulas 1-1 to 1-5 have an n value because the PDI value is 1 or more as a normal mixture in the case of reagents at or above the level of oligomers, unlike single molecules. It does not have to be a single value, and can be specified in a specific range.

More specifically, the compounds represented by Chemical Formulas 1-1 to 1-5 may have the following chemical structures.

[Formula 1-3-1]

[Formula 1-4-1]

[Formula 1-4-2]

[Formula 1-5-1]

[Formula 1-5-2]

The compound represented by Chemical Formula 1 of the present invention, as an organic ligand, may play a role of stabilizing the quantum dot by being coordinated to the surface of the quantum dot.

Conventionally prepared quantum dots generally have a ligand layer on the surface, and the ligand layer immediately after preparation is composed of oleic acid, lauric acid, 2-(2-methoxyethoxy)acetic acid, 2 -[2-(2-methoxyethoxy)ethoxy]acetic acid, and succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl] ester and the like. In this case, the quantum dot according to the present invention includes the compound represented by Formula 1 as a ligand layer, and compared to the strong bonding strength between the thiol group and the surface of the quantum dots, the non-bonding defect on the surface of the quantum dots is due to the weaker bonding strength with the quantum dots. Due to this, the surface protection effect may be lowered. In addition, oleic acid is well dispersed in unsaturated hydrocarbon solvents such as n-hexane, a highly volatile organic compound (VOC), and aromatic solvents such as chloroform and benzene, but has poor dispersibility in solvents such as PGMEA. . The quantum dot according to the present invention includes the compound represented by Formula 1 as a ligand layer, and exhibits excellent dispersibility in a solvent such as PGMEA to improve optical properties.

Quantum dots are not particularly limited as long as they are quantum dot particles capable of emitting light when stimulated by light or electricity. For example, II-VI group semiconductor compounds; Group III-V semiconductor compounds; Group IV-VI semiconductor compounds; Group IV elements or compounds containing them; And it may be selected from the group consisting of combinations thereof, which may be used alone or in combination of two or more.

For example, the II-VI group semiconductor compound is a binary element compound selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, and mixtures thereof; CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, and mixtures thereof; and CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and a quaternary compound selected from the group consisting of mixtures thereof, but is not limited thereto.

The group III-V semiconductor compound is a binary element compound selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; A ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and mixtures thereof; And it may be selected from the group consisting of quaternary compounds selected from the group consisting of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof. It is not limited.

The group IV-VI semiconductor compound is a binary element compound selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; a ternary compound selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; And SnPbSSe, SnPbSeTe, SnPbSTe, and may be at least one selected from the group consisting of quaternary compounds selected from the group consisting of mixtures thereof, but is not limited thereto either.

Although not limited thereto, the group IV element or a compound containing the same may be an element selected from the group consisting of Si, Ge, and mixtures thereof; And it may be selected from the group consisting of a binary element compound selected from the group consisting of SiC, SiGe, and mixtures thereof.

Quantum dots are homogeneous unitary structures; dual structures such as a core-shell structure and a gradient structure; Or it may be a mixed structure thereof, and in the present invention, quantum dots are not particularly limited as long as they can emit light when stimulated by light.

According to an embodiment, the quantum dot has a core-shell structure, and the core includes InP, InZnP, InGaP, CdSe, CdS, CdTe, ZnS, ZnSe, ZnTe, CdSeTe, CdZnS, CdSeS, PbSe, PbS, PbTe, AgInZnS, It includes at least one selected from the group consisting of HgS, HgSe, HgTe, GaN, GaP, GaAs, InGaN, InAs, and ZnO, and the shell is ZnS, ZnSe, ZnTe, ZnO, CdS, CdSe, CdTe, CdO, InP , InS, GaP, GaN, GaO, InZnP, InGaP, InGaN, InZnSCdSe, PbS, TiO, may include one or more selected from the group consisting of SrSe and HgSe, preferably, InP / ZnS, InP / ZnSe , InP/GaP/ZnS, InP/ZnSe/ZnS, InP/ZnSeTe/ZnS, and InP/MnSe/ZnS.

In general, quantum dots may be prepared by a wet chemical process, a metal organic chemical vapor deposition (MOCVD) process, or a molecular beam epitaxy (MBE) process.

The wet chemical process is a method of growing particles by putting a precursor material in an organic solvent. When the crystal grows, the organic solvent is naturally coordinated on the surface of the quantum dot crystal and acts as a dispersant to control the growth of the crystal. The size growth of quantum dot particles can be controlled through a process that is easier and cheaper than vapor deposition such as epitaxy.

The quantum dots according to the present invention may be obtained by replacing a compound (eg, oleic acid) constituting the ligand layer with the compound represented by Formula 1 immediately after preparation of the quantum dots through a ligand exchange reaction.

For example, in the ligand exchange reaction, an organic ligand to be exchanged, that is, a compound represented by Formula 1 is added to a dispersion containing quantum dots to which oleic acid is bonded as a ligand layer, and the reaction is carried out at room temperature to 200° C. for 30 minutes. It can be carried out by stirring for 3 hours to obtain quantum dots to which the compound represented by Formula 1 is bound. If necessary, a process of separating and purifying the quantum dots to which the compound of Formula 1 is bound may be additionally performed.

As described above, the quantum dot according to an embodiment of the present invention can be produced by an organic ligand exchange method under a simple stirring process at room temperature, and thus has the advantage of being mass-produced.

In addition, the quantum dot according to an embodiment of the present invention can maintain a quantum efficiency of about 90% or more compared to the initial quantum efficiency not only after 7 days but also after 15 days, so that it can be stably stored for a long period of time and commercialized for various purposes. .

<Quantum dot light emitting diode>

A quantum dot light-emitting diode (QLED) according to the present invention may include the above-described quantum dots.

A quantum dot light emitting diode is an electroluminescence (EL) type device that emits light by electrically exciting quantum dots.

In the quantum dot light emitting diode, electrons and holes injected from both electrodes form excitons in the quantum dot light emitting layer, and emit light through radiative recombination of the excitons. Since this has the same operation principle as Organic Light-Emitting Diode (OLED), only the light-emitting layer is replaced with quantum dots instead of organic light-emitting materials in a multi-layer device structure using the electron / hole injection layer and transport layer of ordinary OLED as it is. It can be.

The manufacturing method of the quantum dot light emitting diode according to the present invention is not particularly limited, and a method known in the art may be used.

For example, a quantum dot light emitting diode may be manufactured by sequentially stacking an anode, a cathode, an electron injection/transport layer, a light emitting layer, a hole transport layer, and a hole injection layer.

In another embodiment, the method for manufacturing a quantum dot light emitting diode may be manufactured by sequentially stacking a cathode, an electron injection/transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode. A method for manufacturing a diode may be manufactured by sequentially stacking an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, an electron injection/transport layer, and a cathode.

In this case, the light emitting layer may include the above-described quantum dots.

<Quantum dot film>

The quantum dot film according to the present invention may include the above-described quantum dots.

The quantum dot film includes a polymer resin and a quantum dot dispersion layer including the above-described quantum dots dispersed in the polymer resin.

Examples of the polymer resin include epoxy, epoxy acrylate, lauryl acrylate, norborene, polyethylene, polystyrene, ethylene-styrene copolymer, acrylates including bisphenol A and bisphenol A derivatives, and fluorene derivatives. Acrylates, isobornyl acrylates, polyphenylalkylsiloxanes, polydiphenylsiloxanes, polydialkylsiloxanes, silsesquioxanes, fluorinated silicones, vinyl and hydride substituted silicones, etc. may be used, and these polymer resins may be used alone or Two or more types may be mixed and used.

The quantum dot film may further include a barrier layer on at least one surface of the quantum dot dispersion layer.

The barrier layer may have an oxygen permeability of 0.001 cm 3 / m 2 day bar or less and a moisture permeability of 0.001 g / m 2 day or less, and include, for example, polyester, polycarbonate, polyolefin, cyclic olefin polymer or polyimide can do.

The quantum dot dispersion layer may have a thickness of 10 μm to 100 μm, and the barrier layer may have a thickness of 50 μm to 70 μm.

The manufacturing method of the quantum dot film according to the present invention is not particularly limited, and a method known in the art may be used.

In one embodiment, a method for manufacturing a quantum dot film,

a) preparing a lower transparent substrate;

b) forming a quantum dot thin film by applying a quantum dot dispersion to a lower transparent substrate; and

c) preparing a quantum dot film by laminating an upper transparent substrate on a quantum dot thin film; may include.

<Light conversion resin composition>

The method for preparing the light conversion resin composition of the present invention is not particularly limited, and methods known in the art may be used.

For example, the light conversion resin may include the above-described quantum dot, binder resin, photopolymerizable compound, thermally polymerizable compound, photopolymerization initiator, and solvent, in addition to colorants including pigments and dyes, scattering particles, etc. Accordingly, components known in the art may be further included.

The light conversion resin composition prepared in this way can be preferably used in the manufacture of a color filter and an image display device including the same.

<Color filter>

A pattern formation method for forming the color filter of the present invention may use a method known in the art.

For one embodiment, the pattern forming method,

a) applying a light conversion resin composition to a substrate;

b) a prebaking step of drying the solvent;

c) curing the exposed area by applying actinic light to a photomask on the obtained film;

d) performing a developing process of dissolving the unexposed portion using an aqueous alkali solution; and

e) drying and post-baking; may be included.

The substrate may be a glass substrate or a polymer substrate, but is not limited thereto. As the glass substrate, soda lime glass, glass containing barium or strontium, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass or quartz can be preferably 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. .

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

In addition, the exposure performed after the prebaking is performed by an exposure machine to expose through a photomask, thereby sensitizing only the portion corresponding to the pattern. At this time, as the light to be irradiated, for example, visible light, ultraviolet rays, X-rays, electron beams, and the like can be used.

The development step of dissolving the unexposed portion using an alkaline aqueous solution after exposure is performed for the purpose of removing the photosensitive resin composition of the unremoved portion of the unexposed portion, and a desired pattern is formed by this development. As a developing solution suitable for development using this aqueous alkali solution, for example, an aqueous solution of a carbonate of an alkali metal or an alkaline earth metal can be used. In particular, using an aqueous alkali solution containing 1 to 3% by weight of a carbonate such as sodium carbonate, potassium carbonate, or lithium carbonate at a temperature of 10 to 50° C., preferably 20 to 40° C., using a developing device or an ultrasonic cleaner. can be done by

The post-baking is performed to increase adhesion between the patterned film and the substrate, and may be performed by heat treatment at, for example, 80 to 250° C. for 10 to 120 minutes. Post-baking, like pre-baking, can be performed using an oven, hot plate, or the like.

<Light conversion laminated base material>

The light conversion laminated base material according to the present invention includes a cured product of a light conversion resin composition. Since the light conversion laminated substrate includes a light conversion resin composition that can be coated on a glass substrate, it is possible to use a solvent that does not correspond to substances harmful to the human body, thereby improving worker safety and product productivity.

The light conversion layered substrate may be silicon (Si), silicon oxide (SiOx) or a polymer substrate, and the polymer substrate may be polyethersulfone (PES) or polycarbonate (PC).

The light-conversion laminated substrate may be formed by applying the light-conversion resin composition and thermally curing it.

<Image display device>

An image display device according to the present invention includes the above-described color filter or light conversion laminated substrate. The image display device is specifically, a liquid crystal display (liquid crystal display device; LCD), an organic EL display (organic EL display device), a liquid crystal projector, a display device for game machines, a display device for portable terminals such as mobile phones, and a display for digital cameras. device, a display device such as a display device for car navigation, and the like, and a color display device is particularly suitable.

The image display device may further include configurations known to those skilled in the art, except for including the light conversion laminated substrate. That is, the present invention includes an image display device to which the light conversion laminated substrate of the present invention can be applied.

An image display device including a color filter or a light conversion laminate according to the present invention may have excellent characteristics in color reproducibility, luminance, light resistance and reliability.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to explain the present invention in more detail, and the scope of the present invention is not limited by the following examples.

Synthesis Example 1: Synthesis of InP/ZnS core-shell quantum dots

In a 3-neck flask, 0.05839 g of indium acetate, 0.12019 g of oleic acid and 10 mL of 1-octadecene (ODE) were placed. The flask was degassed at 110° C. and 100 mTorr for 30 minutes while stirring, and then heated at 270° C. under inert gas until the solution became transparent.

As a phosphorus (P) precursor, 0.025054 g of tris(trimethylsilyl)phosphine was prepared, put into 0.5 mL of 1-octadecene and 0.5 mL of tri-n-octylphosphine, stirred, and placed in the flask heated to 270° C. under inert gas. was rapidly injected. After reacting for 1 hour, the reaction was terminated by rapidly cooling. Then, when the temperature of the flask reached 100° C., 10 mL of toluene was injected and then transferred to a 50 mL centrifuge tube. After adding 10 mL of ethanol, it was purified twice using the precipitation and redispersion method. The purified InP core nanoparticles were dispersed in 1-octadecene and then stored.

3.669 g of zinc acetate, 20 mL of oleic acid, and 20 mL of 1-octadecene were added to a three-necked flask, followed by degassing at 110 °C and 100 mTorr for 30 minutes with stirring, and then under inert gas until the solution became clear. After heating to a temperature of 270 ° C., the mixture was cooled to 60 ° C. to obtain a zinc precursor solution in the form of transparent zinc oleate.

Put 0.6412 g of sulfur (S) and 10 mL of tri-n-octylphosphine (TOP) in a three-necked flask, heat to a temperature of 80 ° C. while stirring in an inert gas atmosphere until the solution becomes transparent, and then cool to room temperature. TOP: A sulfur precursor solution in the form of S was obtained.

In a separate three-necked flask, the prepared InP core nanoparticle solution was put, the temperature of the flask was adjusted to 300 ° C, and then 0.6 mL of the prepared zinc precursor solution was rapidly injected using a syringe. Thereafter, 0.3 mL of the previously prepared sulfur precursor solution was injected into the flask at a rate of 2 mL/hr using a syringe pump. After the injection was completed, the reaction was further proceeded for 3 hours, and the reaction was terminated by rapidly cooling. When the temperature of the flask reached 100° C., 10 mL of toluene was injected, and then transferred to a 50 mL centrifuge tube. After adding 10 mL of ethanol, it was purified twice using the precipitation and redispersion method. The purified InP/ZnS core-shell nanoparticles were dispersed in n-chloroform and then stored. The solid content was adjusted to 10%. The maximum emission wavelength was 525 nm.

Synthesis Example 2: Synthesis of InP/ZnSe/ZnS core-shell quantum dots

Indium acetate (Indium acetate) 0.4mmol (0.058g), palmitic acid (palmitic acid) (palmitic acid) (palmitic acid) 0.6mmol (0.15g) and 1-octadecene (octadecene) 20mL was put into the reactor and heated to 120 ℃ under vacuum. After 1 hour, the atmosphere in the reactor was changed to nitrogen. After heating to 280 ° C., a mixed solution of 0.2 mmol (58 μl) of tris (trimethylsilyl) phosphine (TMS3P) and 1.0 mL of trioctylphosphine was quickly injected and reacted for 0.5 minutes.

2.4 mmol (0.448 g) of zinc acetate, 4.8 mmol of oleic acid and 20 mL of trioctylamine were then charged into the reactor and heated to 120° C. under vacuum. After 1 hour, the atmosphere in the reactor was changed to nitrogen, and the temperature of the reactor was raised to 280°C. 2 mL of the previously synthesized InP core solution was added, followed by 4.8 mmol of selenium (Se/TOP) in trioctylphosphine, and the final mixture was reacted for 2 hours. Ethanol was added to the reaction solution rapidly cooled to room temperature, and the precipitate obtained by centrifugation was filtered under reduced pressure and dried under reduced pressure to form an InP/ZnSe core-shell.

Then, 2.4 mmol (0.448 g) of zinc acetate, 4.8 mmol of oleic acid and 20 mL of trioctylamine were charged into the reactor and heated to 120° C. under vacuum. After 1 hour, the atmosphere in the reactor was changed to nitrogen, and the temperature of the reactor was raised to 280°C. 2 mL of the previously synthesized InP core solution was added, followed by 4.8 mmol of sulfur (S/TOP) in trioctylphosphine, and the final mixture was reacted for 2 hours. Ethanol was added to the reaction solution quickly cooled to room temperature, and the precipitate obtained by centrifugation was filtered under reduced pressure and dried under reduced pressure to obtain quantum dots having an InP/ZnSe/ZnS core-shell structure, and then dispersed in chloroform. The solid content was adjusted to 10%. The maximum emission wavelength was 520 nm.

Preparation of quantum dots according to Examples and Comparative Examples

Example 1. Ligand displacement reaction 1 (LE-1)

5mL of the quantum dot solution obtained in Synthesis Example 1 was placed in a centrifuge tube and 20mL of ethanol was added to precipitate it. Through centrifugation, the supernatant was discarded, and 3 mL of chloroform was added to the precipitate to disperse the quantum dots, and then, Lipoamido-dPEG® 8-acid (Sigma-Aldrich Co.) was reacted for one hour while heating at 60 ° C. under a nitrogen atmosphere. Quantum dots were precipitated by adding 25mL of n-hexane to the reaction mixture, centrifuged to separate the precipitate, and then PGMEA was added to a solid content of 10% and dispersed. The maximum emission wavelength was 520 nm.

[Formula 1-4-1]

Example 2. Ligand displacement reaction 2 (LE-2)

The procedure was performed in the same manner as in Example 1, except that 1.0 g of Lipoamido-dPEG® 12-acid (Sigma-Aldrich) was used instead of the ligand used in Example 1. The solid content was adjusted to 10%. The maximum emission wavelength was 520 nm.

[Formula 1-4-2]

Example 3. Ligand displacement reaction 3 (LE-3)

The same procedure as in Example 1 was performed except that 1.0 g of LA-PEG-COOH,2K (Biochempeg Scientific) was used instead of the ligand used in Example 1. The solid content was adjusted to 10%. The maximum emission wavelength was 521 nm.

Example 4. Ligand displacement reaction 4 (LE-4)

The same procedure as in Example 1 was performed except that 1.0 g of LA-PEG-COOH,5K (Biochempeg Scientific) was used instead of the ligand used in Example 1. The solid content was adjusted to 10%. The maximum emission wavelength was 522 nm.

Example 5. Ligand displacement reaction 5 (LE-5)

5mL of the quantum dot solution obtained in Synthesis Example 2 was placed in a centrifuge tube and 20mL of ethanol was added to precipitate it. Discard the supernatant through centrifugation, add 3mL of chloroform to the precipitate to disperse the quantum dots, add 1.0g of m-dPEG®8-Lipoamide (Sigma-Aldrich), add , and heat at 60℃ under a nitrogen atmosphere for one hour. reacted

Next, 25mL of n-hexane was added to the reaction mixture to precipitate the quantum dots, and centrifugation was performed to separate the precipitate, and then PGMEA was added to a solid content of 10% to disperse it. The maximum emission wavelength was 520 nm.

[Formula 1-3-1]

Example 6. Ligand displacement reaction 6 (LE-6)

The same procedure as in Example 5 was performed except that 1.0 g of mPEG-LA,2K (Biochempeg Scientific) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 521 nm.

Example 7. Ligand displacement reaction 7 (LE-7)

The procedure was performed in the same manner as in Example 5, except that 1.0 g of mPEG-LA,5K (Biochempeg Scientific) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 522 nm.

Example 8. Ligand displacement reaction 8 (LE-8)

The same procedure as in Example 5 was performed except that SH-PEG-LA,1K (Biochempeg Scientific) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 520 nm.

Example 9. Ligand displacement reaction 9 (LE-9)

The same procedure as in Example 5 was performed except that SH-PEG-LA,2K (Biochempeg Scientific) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 521 nm.

Example 10. Ligand displacement reaction 10 (LE-10)

The procedure was performed in the same manner as in Example 5, except that Lipoamido-PEG2-alcohol (BroadPharm Co.) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 521 nm.

[Formula 1-5-1]

Example 11. Ligand displacement reaction 11 (LE-11)

The same procedure as in Example 5 was performed except that Lipoamido-PEG3-alcohol (BroadPharm Co.) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 521 nm.

[Formula 1-5-2]

Comparative Example 1: Quantum dot preparation of InP/ZnS core alone without ligand exchange reaction

The quantum dots of Synthesis Example 1 in which oleic acid was bound to the surface were dispersed in chloroform at a concentration of 10%.

Comparative Example 2: Preparation of InP/ZnSe/ZnS core-shell quantum dots without ligand exchange reaction

The quantum dots of Synthesis Example 2 in which oleic acid is bound to the surface were dispersed in chloroform at a concentration of 10%.

Comparative Example 3. Ligand Substitution Reaction 10 (LE-10)

Except for using Thioctic acid (Sigma Aldrich Co.) instead of the ligand used in Example 5, the procedure was performed in the same manner as in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 525 nm.

[Formula 2-1]

Comparative Example 4. Ligand Substitution Reaction 11 (LE-11)

The same procedure as in Example 5 was performed except that LA-PEG-NH2,2K (Biochempeg Scientific) was used instead of the ligand used in Example 5. The solid content was adjusted to 10%. The maximum emission wavelength was 525 nm.

test example

(1) Quantum efficiency

Quantum efficiency (QY%) at the beginning of the preparation of the quantum dot dispersions of Examples 1 to 11 and Comparative Examples 1 to 4 and absolute quantum efficiency (QY%) after being left at room temperature for 15 days were measured using QE-2100 (Otsuka Co.) did

Since quantum efficiency is reduced by surface oxidation of quantum dots, oxidation stability can be confirmed by measuring the amount of decrease in quantum efficiency. The measurement results are shown in Table 1 below. When the ΔQY% value is 15 or less, excellent quantum efficiency is obtained.

[Table 1]

(2) light fastness

The maximum absorption wavelength (λmax) at the initial stage of preparing the quantum dot dispersions of Examples 1 to 11 and Comparative Examples 1 to 4 and the absolute quantum efficiency after being left in a blue LED light source for 7 days at room temperature were measured using QE-2100 (Otsuka Co.) . When QY (%) is 15 or less, it has excellent light fastness.

When the surface of a quantum dot is oxidized due to a defect that is not protected by a ligand, the quantum efficiency is lowered. Reliability can be confirmed by measuring the decrease in absolute quantum efficiency. The measurement results for this are shown in Table 2 below.

[Table 2]

As shown in Tables 1 and 2, the quantum dots of Examples 1 to 11 having the ligand of Chemical Formula 1 according to the present invention have a ΔQY% value, that is, a change in quantum efficiency between initial and left as small as 15 or less, so that oxidation stability is high. It was confirmed that it had excellent reliability by having an excellent value of 15 or less in light fastness accordingly.

On the other hand, in the case of the quantum dots of Comparative Examples 1 to 4 not containing the ligand of the present invention, the amount of change in quantum efficiency was increased by more than 4 times compared to the quantum dot of the present invention, and the amount of change in light resistance was also 3.9 times or more, and the oxidative stability and light resistance It was confirmed that this was very low, and it was confirmed that the reliability was significantly lowered.

Claims (13)

As a quantum dot for an image display device having a ligand layer on the surface,
Quantum dots, characterized in that the ligand layer comprises a compound represented by the following formula (1):
[Formula 1]

In Formula 1,
A is a straight-chain or branched chain mercaptoalkyl group having 1 to 10 carbon atoms, a straight-chain or branched chain carboxyl group having 1 to 10 carbon atoms, or ego,
Wherein R is a direct bond or a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,
Wherein R ₁ is a direct bond or a straight-chain or branched alkylene group having 1 to 10 carbon atoms, wherein R ₂ is hydrogen or a linear or branched-chain alkyl group having 1 to 10 carbon atoms, quantum dots.
* represents a bonding hand,
n is an integer from 1 to 250;
The method of claim 1,
In Formula 1, A is a linear mercaptoalkyl group having 1 to 10 carbon atoms, a linear carboxyl group having 1 to 10 carbon atoms, or ego,
Wherein R is a direct bond or a straight-chain alkylene group having 1 to 10 carbon atoms,
In the above, R ₁ is a direct bond or a straight chain alkylene group having 1 to 10 carbon atoms,
Wherein R ₂ is hydrogen or a straight-chain alkyl group having 1 to 10 carbon atoms, quantum dots.
The method of claim 1,
The ligand layer comprises at least one selected from the group consisting of compounds represented by the following Chemical Formulas 1-1 to 1-5, quantum dots:
[Formula 1-1]

In Formula 1-1, n is an integer from 1 to 250.
[Formula 1-2]

In Formula 1-2, n is an integer from 1 to 250.
[Formula 1-3]

In Formula 1-3, n is an integer from 1 to 250.
[Formula 1-4]

In Chemical Formula 1-4, n is an integer from 1 to 250.
[Formula 1-5]

In Formula 1-5, n is an integer from 1 to 250.
The method of claim 1,
The ligand layer is composed of oleic acid, lauric acid, 2-(2-methoxyethoxy)acetic acid, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and A quantum dot further comprising at least one member selected from the group consisting of succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl] ester.
The method of claim 1,
The quantum dots have a core-shell structure,
The core is InP, InZnP, InGaP, CdSe, CdS, CdTe, ZnS, ZnSe, ZnTe, CdSeTe, CdZnS, CdSeS, PbSe, PbS, PbTe, AgInZnS, HgS, HgSe, HgTe, GaN, GaP, GaAs, InGaN, InAs And at least one selected from the group consisting of ZnO,
The shell is selected from the group consisting of ZnS, ZnSe, ZnTe, ZnO, CdS, CdSe, CdTe, CdO, InP, InS, GaP, GaN, GaO, InZnP, InGaP, InGaN, InZnSCdSe, PbS, TiO, SrSe and HgSe Quantum dot, characterized in that it comprises one or more species.
The method of claim 1,
The quantum dot is characterized in that it comprises at least one selected from the group consisting of InP / ZnS, InP / ZnSe, InP / GaP / ZnS, InP / ZnSe / ZnS, InP / ZnSeTe / ZnS and InP / MnSe / ZnS quantum dot.
A quantum dot light emitting diode (Quantum Dot Light-Emitting Diode, QLED) comprising the quantum dot according to any one of claims 1 to 6.
A quantum dot film comprising the quantum dots according to any one of claims 1 to 6.
A light conversion resin composition comprising the quantum dots according to any one of claims 1 to 6.
A color filter formed using the light conversion resin composition according to claim 9.
A light conversion laminated base material formed by using the light conversion resin composition according to claim 9.
An image display device including the color filter according to claim 10.
An image display device comprising the light conversion laminated substrate according to claim 11.