Hybrid organic/inorganic quantum dot composite and method for preparing the same

Abstract

A hybrid organic/inorganic quantum dot composite with high reliability is disclosed. The hybrid organic/inorganic quantum dot composite includes quantum dot, polymer resin, and silica, in which the silica is formed in the polymer resin, one end of the polymer resin forms a chemical bond with the quantum dot, and another end of the polymer resin includes a functional group capable of forming an additional chemical bond. The hybrid organic/inorganic quantum dot composite is resistant to moisture and oxygen permeation, and thus, it is not degraded easily by bonding oxygen and moisture to quantum dots even if moisture and oxygen permeate into the composite. The quantum dot composite may be used as a secondary raw material capable of being processed into another form while maintaining physical properties of quantum dots as a primary raw material.

Claims

1. A hybrid organic/inorganic quantum dot composite comprising: a quantum dot; a polymer resin; and a ligand, wherein: one end of the ligand and one end of the polymer resin are bonded by SiOSi bond, another end of the ligand forms a chemical bond with the quantum dot, another end of the polymer resin comprises a functional group capable of forming an additional chemical bond, and the functional group is an unsaturated functional group selected from the group consisting of acryl, methacryl, vinyl, alkenyl and epoxy.

2. The quantum dot composite of claim 1, wherein the quantum dot has a core-shell structure.

3. The quantum dot composite of claim 1, wherein the ligand forms a coordination bond with the quantum dot.

4. The quantum dot composite of claim 1, wherein the quantum dot is cadmium-based quantum dot, II-VI group quantum dot, III-V group quantum dot, IV-VI group quantum dot, or I-III-V group quantum dot.

5. The quantum dot composite of claim 1, wherein the quantum dot comprises InP, ZnSe, ZnTe, CdSe, CdTe, or CdS.

6. A hybrid organic/inorganic quantum dot composition comprising the quantum dot composite of claim 1.

7. The composition of claim 6, further comprising one or more additives selected from the group consisting of a silane compound, a polyfunctional acryl monomer, a polyfunctional epoxy monomer, an initiator, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer.

8. An optical device comprising the quantum dot composite of claim 1, wherein the optical device is selected from the group consisting of a plate, a color filter, an LED package, an LED chip, a color conversion filter, an optical conversion film, a QD film, an On Chip, and a light emitting package.

9. The optical device of claim 8, wherein the optical device does not comprise a barrier film.

10. The optical device of claim 8, wherein the optical device is formed by curing a hybrid organic/inorganic quantum dot composition comprising the quantum dot composite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a flow chart of the entire process of preparing a final part such as a plate according to an embodiment of the present invention.

(2) FIG. 2 is a schematic diagram briefly showing a manufacturing mechanism of a quantum dot complex according to process steps according to an embodiment of the present invention.

(3) FIG. 3 is a schematic view illustrating the concept of an integral hybrid QD composite in which quantum dot-inorganic-organic materials are chemically bonded by adding and reacting quantum dots surrounded by ligands having a silane group according to an embodiment of the present invention.

(4) FIG. 4A illustrates a schematic view of a hybrid organic/inorganic quantum dot composite including quantum dots and a polymer resin which directly forms a chemical bond with the quantum dots, in which silica particles are included in the resin according to an embodiment of the present invention.

(5) FIG. 4B exemplifies a molecular structure of a functional group which may be included at the ends of the resin according to an embodiment of the present invention.

(6) FIG. 5A shows a hybrid organic/inorganic quantum dot composite obtained when the ends of the resin include an acrylate group according to an embodiment of the present invention.

(7) FIG. 5B shows a hybrid organic/inorganic quantum dot composite obtained by preparing the composite in the same manner as in FIG. 5a, except that an unsaturated functional group is not included at the ends of the resin according to an embodiment of the present invention.

(8) FIG. 6 illustrates an expected structure of a final quantum dot plate according to an embodiment of the present invention.

(9) FIG. 7 illustrates a graph showing reliability measured by cutting samples obtained in the Example.

DETAILED DESCRIPTION OF INVENTION

(10) Hereinafter, the present invention will be described in more detail through the Examples. These Examples are provided only for more specifically describing the present invention, and it will be obvious to a person with ordinary skill in the art to which the present invention pertains that the scope of the present invention is not limited by these Examples.

EXAMPLES

(11) A) Synthesis of Quantum Dots and Ligand Substitution

(12) Indium chloride (InCl.sub.3) and zinc acetate (ZnAc.sub.2) were put into 5 ml of oleylamine solvent at a mole ratio of 2 mmol:1 mmol, and the resulting mixture was vacuum-deaerated at 100 C. for 1 hour. The temperature was increased to 210 C., and then 1.5 mmol of tris(dimethylamino)phosphine was injected or added into the mixture, and reaction was performed for 20 minutes to form an InP core. 10 ml of a shell solution prepared in advance was injected or added into the core, and reaction was performed for 24 hours to form a ZnS shell. The shell solution was prepared by adding zinc stearate (ZnSt.sub.2) and sulfur powder to 10 ml of a trioctylphosphine solvent at a mole ratio of 2 mmol:10 mmol, vacuum-deaerating the resulting mixture at 100 C. for 1 hour, and then increasing the temperature to 200 C.

(13) An InP/ZnS quantum dot having a core-shell structure which was surrounded by ligands such as oleylamine, stearate, and trioctylphosphine was synthesized by using the colloid solution synthesis method, and a process of substituting the ligands with mercaptosilane (MPS) was performed.

(14) Specifically, the test was performed at a ratio of the quantum dot solution (40 mg/ml):mercaptosilane (MPS) (20 mg/ml)=1:10 as a basis, and also at a ratio of 1:1 to 1:50. The test was performed at a temperature range of 30 to 100 C., and the substitution time was from 30 minutes to 24 hours.

(15) B) Sol-Gel Reaction

(16) The substituted quantum dots prepared in A), methacryloxypropyltrimethoxysilane, and a catalyst (DI water, HCl) were mixed, and the resulting mixture was reacted at a temperature of 70 to 80 C. for 12 hours. As the composition ratio of the sol-gel reaction, a ratio of the quantum dots (40 mg/ml):silane (methacryloxypropyltrimethoxysilane):the catalyst (DI water+HCl solution) was basically set as 1:5:5.

(17) The ratio can be adjusted from 1:1:1 to 1:50:50 by increasing the ratio of the quantum dots, and the ratio of silane and the catalyst can also be adjusted from 1:1 to at least 1:10 or up to 10:1.

(18) C) Drying Process

(19) The drying condition can be adjusted from 30 C. to 200 C., and drying can be performed in vacuum or in the atmosphere depending on the conditions. In the present Example, a hybrid organic/inorganic quantum dot composite was prepared by performing drying at a temperature of 110 C. for 24 hours.

(20) FIG. 4A illustrates a schematic view of a hybrid inorganic quantum dot composite including quantum dots, polymer resin forming a direct chemical bond with the quantum dots, and silica particles included in the resin. Since an unsaturated functional group such as acrylate or vinyl is present at the end (a portion marked with a circle in FIG. 4A) of the resin prepared in the present Example, further chemical reactions are possible. The molecular structure of a functional group which may be included at the end of the resin is exemplified in FIG. 4B.

(21) Measurement of Flowability

(22) As described above, drying was performed at a temperature of 110 C. for 24 hours, and then the flowability of the QD-resin-silica composite was evaluated in accordance with the ASTM 1238. As a result of comparing the case where an unsaturated functional group such as acrylate is included as a functional group which may form an additional chemical bond at the end of the resin with the case where the unsaturated functional group is not included, it was confirmed that a hybrid organic/inorganic quantum dot composite including an unsaturated functional group such as acrylate at the end of the resin has excellent flowability because of the functional group capable of forming an additional bond in a curing process (FIG. 5A).

(23) On the other hand, even if having the same structure of QD-resin-silica composite, the physical property of the quantum dot composite having a saturated functional group such amino at the end of the resin was evaluated to determine whether it is powdery or brittle (FIG. 5B).

(24) D) Formulation Process

(25) A hybrid organic/inorganic quantum dot composite composition was prepared by mixing and stirring 5 wt % of photo-initiator, 0.1 wt % to 50 wt % of monomer, and an additive with the hybrid organic/inorganic quantum dot composite prepared as described above using a co-rotational apparatus. The viscosity can be adjusted according to the type and content ratio of monomer. It is possible to control the viscosity and impart various characteristics by mixing various monomers and additives. It was confirmed that the reliability tends to decrease when the ratio of the monomer and the additive added in this process increases.

(26) E) Forming and Curing Process

(27) A quantum dot plate in which quantum dots, silica and a polymer are linked together by chemical bonding was formed and cured by a method of reacting the curable functional groups using UV radiation. FIG. 6 illustrates an expected structure of a final quantum dot plate, and FIG. 7 illustrates a graph showing reliability measured by cutting the samples thus obtained.

(28) It was confirmed that the ligand is rarely desorbed even though a material capable of degrading quantum dots such as oxygen or moisture permeates into the quantum dot plate, and the quantum dot plate was firmly fixed with the hybrid organic/inorganic resin through the chemical bonds, and thus exhibited very high reliability without being degraded (FIG. 7).