KR20150027701A - Quantum dot - inorganic particle aggregate and optical element having the same - Google Patents

Abstract

The present invention relates to a quantum dot-inorganic particle aggregate and an optical element including the same. The quantum dot-inorganic particle aggregate are equipped with quantum dots. Multiple inorganic particles surround the quantum dots. The quantum dot-inorganic particle aggregate of a form that the inorganic particles surround the inorganic particle is able to increase thermal stability by maintaining internal quantum efficiency even in high temperature conditions by stabilizing the quantum dots by the inorganic particles. Additionally, the quantum dot-inorganic particle aggregate is able to increase quantum efficiency light incoming to and light emission from the quantum dots, quantum efficiency, as compared with a case that an inorganic layer completely covers the quantum dots.

Description

QUANTUM DOT - INORGANIC PARTICLE AGGREGATE AND OPTICAL ELEMENT HAVING THE SAME -

The present invention relates to a nanocomposite, and more particularly to a complex of a quantum dot and an inorganic particle.

The quantum dot is a semiconductor particle having a core or core-shell structure of several nanometers in size and emits energy obtained through excitation according to the size of the particles as light of various wavelengths, It is effective for lighting applications. In order to apply such quantum dots to the field of LED, it is generally used dispersed in resin solution.

However, quantum dots are problematic in terms of reduction of quantum efficiency due to physicochemical conversion of quantum dots when exposed to an oxidizing environment such as oxygen or moisture or a high temperature. In particular, the results of the accelerated life test at an oxidizing environment and at a high temperature, which is a long-term stability verification method in a curable resin, for applying quantum dots to practical applications such as LEDs, are known to drastically decrease the quantum efficiency according to the treatment time have. This limits the commercial application of quantum dots.

Korean Patent No. 1203173 discloses quantum dots surrounded by a silicon oxide layer. However, since the silicon oxide layer completely surrounds the quantum dots, it may be difficult to emit light. In addition, since the silicon oxide layer is formed through the sol-gel reaction, the process cost is high, and quantum dots damage may occur due to the acid or base added for the sol-gel reaction.

An object of the present invention is to provide quantum dot-inorganic particle aggregates which can stably maintain quantum efficiency of a quantum dot for a long period of time.

Another object of the present invention is to provide a quantum dot-inorganic particle aggregate capable of further improving the quantum efficiency of a quantum dot.

According to one aspect of the present invention, there is provided a quantum dot-inorganic particle aggregate. The aggregate has a quantum dot and a plurality of inorganic particles agglomerated on the outside of the quantum dot.

The quantum dots are capped by a first capping layer, and each of the inorganic particles may be capped by a second capping layer.

The first capping layer may be a nonpolar organic ligand. The first capping layer may be a layer of material selected from the group consisting of phosphine oxides having nonpolar organic groups, phosphines, amines, organic acids, phosphonic acids, phosphinic acids, thiols, and combinations thereof.

The second capping layer may be a nonpolar organic ligand. The second capping layer may be a layer of a material selected from the group consisting of phosphine oxides having nonpolar organic groups, phosphines, amines, organic acids, phosphonic acids, phosphinic acids, thiols, silanes, alkoxysilanes, have.

The first capping layer and the second capping layer may be the same or different nonpolar organic ligands. In this case, the non-polar organic group of the first capping layer and the non-polar organic group of the second capping layer may inter-digitate.

The inorganic particles may be titanium oxide, silicon oxide, or aluminum oxide. The quantum dots have a multi-layer structure in the form of a single layer or a core-shell type, and each layer of the quantum dots has a structure of CdS, CdO, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, MnS, MnO, MnSe, MnTe, , MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe, BaO, BaS, BaSe, BaTE, HgO, HgS, HgSe, HgTe, Al2O3, Al2S3, Al2Se3, Al2Te3, Ga2O3, Ga2S3, Ga2Se3 , In2S3, In2Se3, In2Te3, SiO2, GeO2, SnO2, SnS, SnSe, SnTe, PbO, PbO2, PbS, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN , InP, InAs, InSb, BP, Si, Ge, and combinations thereof.

According to another aspect of the present invention, there is provided a method of forming a quantum dot-inorganic particle aggregate. First, a quantum dot dispersion in which quantum dots are dispersed in a first solvent is provided. Thereby providing an inorganic particle dispersion in which the inorganic particles are dispersed in the second solvent. The inorganic particle dispersion is heated. The quantum dot dispersion and the heated inorganic particle dispersion are mixed to form a mixed solution. The mixed solution is cooled to form a quantum dot-inorganic particle aggregate.

The quantum dots are capped by a first capping layer, and each of the inorganic particles may be capped by a second capping layer. The first solvent may be a nonpolar solvent, and the second solvent may also be a nonpolar solvent. Alternatively, the first solvent may be a nonpolar solvent, and the second solvent may be a mixture for mixing a nonpolar solvent and a polar solvent. The molar ratio of the quantum dots to the inorganic particles in the mixed solution may be 1: 4 to 1:12.

According to embodiments of the present invention, inorganic particles can form quantum dot-inorganic particle aggregates in the form of surrounding the quantum dots. In this case, the quantum dots can be stabilized by the inorganic particles, and the internal quantum efficiency can be maintained even in a high temperature environment, and the heat resistance can be improved. In addition, since the quantum dots are surrounded by the inorganic particles not completely covering the inorganic layer, the light inflow to the quantum dots and the light emitting efficiency are improved as compared with the case where the inorganic layer completely encapsulates the quantum dots. That is, .

1 is a flow chart showing a method of manufacturing a quantum dot-inorganic particle aggregate according to an embodiment of the present invention.
2A is a schematic view showing a quantum dot-inorganic particle aggregate manufactured by the method described with reference to FIG.
FIG. 2B is a schematic view showing an enlarged view of FIG. 2A. FIG.
3 is a cross-sectional view of an optical element according to an embodiment of the present invention.
4 is a TEM photograph of the aggregate of the quantum dot-silica nanoparticles prepared in Experimental Example 2. FIG.
FIGS. 5 and 6 are graphs showing changes in the photoluminescence intensities of the light emitting diodes manufactured in Experimental Example 3 and Comparative Example 1, respectively, over time.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification. Herein, that a layer is located on another layer may mean that not only these layers are directly in contact but also another layer (s) is located between these layers.

1 is a flow chart showing a method of manufacturing a quantum dot-inorganic particle aggregate according to an embodiment of the present invention.

Referring to FIG. 1, a quantum dot dispersion in which quantum dots are dispersed in a first solvent is provided (S11). Each of the quantum dots may be capped by a first capping layer.

The quantum dot may have a multi-layer structure in the form of a single layer or a core-shell. Each of the layers of the quantum dots may include at least one of CdS, CdO, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, MnS, MnO, MnSe, MnTe, MgO, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, BaO, BaS, BaSe, BaTE, HgO, HgS, HgSe, HgTe, Al2O3, Al2S3, Al2Se3, Al2Te3, Ga2O3, Ga2S3, Ga2Se3, Ga2Te3, In2O3, In2S3, In2Se3, In2Te3, Sn, SnSe, SnTe, PbO, PbO2, PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, Ge, Or a material layer selected from the group consisting of these materials.

The first capping layer is a ligand layer or self-assembled monolayer coordinately bonded to the surface of the quantum dots, and can prevent agglomeration between the quantum dots in the first solvent. Also, the first capping layer may be a nonpolar organic ligand. In one example, the capping layer can be a layer of a material selected from the group consisting of phosphine oxides having non-polar organic groups, phosphines, amines, organic acids, phosphonic acids, phosphinic acids, thiols, and combinations thereof. The nonpolar organic group may be a long chain alkyl group or an aryl group, and the long chain alkyl group may be a C6 to C20 alkyl group, for example, a straight chain alkyl group. As an example, the first capping layer may be formed of a material selected from the group consisting of hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), octylphosphinic acid (OPA), trioctylphosphine (TOP), tri- (n- But are not limited to, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, Thiol, dodecanethiol, and combinations thereof.

The first solvent may be a solvent capable of dispersing the quantum dots. In the quantum dot dispersion, the first capping layer may be dissolved and the quantum dots capped by the first capping layer may be dispersion stabilized. Specifically, when the first capping layer is nonpolar, the first solvent may be a nonpolar solvent, for example, benzene, xylene, toluene, cyclohexane, or carbon tetrachloride.

On the other hand, an inorganic particle dispersion in which inorganic particles are dispersed in a second solvent is provided (S13). Each of the inorganic particles may be capped by a second capping layer. The second solvent may be a solvent capable of dispersing the inorganic particles capped by the second capping layer.

The inorganic particles may be inorganic nanoparticles. The inorganic particles may be titanium oxide, silicon oxide, or aluminum oxide.

The second capping layer is a ligand layer or self-assembled monolayer coordinately bonded to the surface of the inorganic particles, and can prevent agglomeration between the inorganic particles in the second solvent. Also, the second capping layer may be a nonpolar organic ligand. In one embodiment, the second capping layer is formed from a group consisting of phosphine oxide having a nonpolar organic group, phosphine, amine, organic acid, phosphonic acid, phosphinic acid, thiol, silane, alkoxysilane, Selected material layer. The nonpolar organic group may be a long chain alkyl group or an aryl group, and the long chain alkyl group may be a C6 to C20 alkyl group, for example, a straight chain alkyl group. In one embodiment, the capping layer is formed from a material selected from the group consisting of hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), octylphosphinic acid (OPA), trioctylphosphine (TOP), tri- (n- But are not limited to, dicyclohexylamine, dibutylamine, dibutylamine, dibutylamine, dibutylamine, dibutylamine, dibutylamine, dibutylamine, Dodecanethiol, hexadecyl trimethoxysilane, and combinations thereof.

The second solvent may be a solvent capable of dispersing the inorganic particles capped by the second capping layer. Specifically, when the second capping layer is nonpolar, the second solvent may be a nonpolar solvent, for example, benzene, xylene, toluene, cyclohexane, or carbon tetrachloride. Further, the first solvent and the second solvent can be the same solvent and can be, for example, toluene.

Such inorganic particles may have a hydroxyl functional group, for example, a hydroxyl functional group partially present on its surface or on a part of the capping layer. In this case, the second capping layer is difficult to completely dissolve in the second solvent at room temperature, so that the inorganic particles capped by the second capping layer are hardly dispersed and stabilized in the second solvent at room temperature. Thus, the inorganic particle dispersion may be opaque at room temperature.

The second solvent may be used for mixing the non-polar solvent and the polar solvent. The polar solvent may be ethanol, N-methyl-2-pyrrolidone, methyl ethyl ketone (MEK), NN-dimethyl formamide (DMF), or water. In the second solvent, the polar solvent may be added at about 5 to about 15 wt%.

The inorganic particle dispersion is heated to disperse and stabilize the inorganic particles capped by the second capping layer (S15). In this case, the inorganic particle dispersion liquid can be changed transparently. When the second solvent in the inorganic particle dispersion is a mixed solvent of a nonpolar solvent and a polar solvent as described above, the dispersibility of the inorganic particles in the heated inorganic particle dispersion can be further improved.

Thereafter, the quantum dot dispersion and the heated inorganic particle dispersion are mixed to form a mixed solution (S17). The molar ratio of the quantum dots to the inorganic particles in the mixed solution may be 1: 4 to 1:12. When the second solvent in the inorganic particle dispersion is a mixed solvent of a non-polar solvent and a polar solvent as described above, the quantum dots capped by the first capping layer may be unstable in the mixed solution. In other words, when the second solvent in the inorganic particle dispersion is a mixed solvent of a non-polar solvent and a polar solvent as described above, the inorganic particles capped by the second capping layer in the mixture solution have improved dispersibility The quantum dot capped by the first capping layer may have a rather reduced dispersibility.

On the other hand, the quantum dot dispersion may also be heated before forming the mixed solution.

The temperature of the mixed solution, the heated inorganic particle dispersion, or the heated quantum dot dispersion may be about 150 degrees (C) or less so that the quantum dots are not damaged. However, in order for the second capping layer to sufficiently dissolve in the mixed liquid, the temperature of the mixed liquid or the heated inorganic particle dispersion may be about 80 ° C or more. Accordingly, both quantum dots capped by the first capping layer and inorganic particles capped by the second capping layer may be dispersed and stabilized and mixed well.

Subsequently, the mixed liquid is cooled (S19). In this process, the quantum dots capped by the first capping layer and the inorganic particles capped by the second capping layer can aggregate and form a quantum dot-inorganic particle aggregate. Specifically, as described above, as the temperature is lowered, the inorganic particles capped by the second capping layer become coagulated while the dispersion stability is lowered. At this time, the inorganic particles aggregate together with the quantum dots dispersed evenly around. In this case, the non-polar organic group in the first capping layer, for example an alkyl chain and a non-polar organic group in the second capping layer, for example an alkyl chain, inter-digitate and stabilize the quantum dot- Can be formed. When the molar ratio of the quantum dots and the inorganic particles in the mixed liquid is adjusted as described above, the inorganic particles can form quantum dot-inorganic particle aggregates in the form of surrounding the quantum dots. In this case, the quantum dots can be stabilized by the inorganic particles, and the internal quantum efficiency can be maintained even in a high temperature environment, and the heat resistance can be improved. In addition, since the quantum dots are surrounded by the inorganic particles not completely covering the inorganic layer, the light inflow to the quantum dots and the light emitting efficiency are improved as compared with the case where the inorganic layer completely encapsulates the quantum dots. That is, . In addition, since the sol-gel reaction is not used in forming the quantum dot-inorganic particle agglomerates, the process cost can be lowered. Further, since the acid or base to be used in the sol-gel reaction is not used, The damage can be suppressed.

The temperature of the mixed solution after cooling may be room temperature. In cooling the mixed solution, the cooling rate may be about 1 degree / minute (C / min) to about 200 degrees / minute (C / min). The shape and size of the quantum dot-inorganic particle agglomerate to be produced may vary depending on the cooling rate or the molar ratio of the quantum dot to the inorganic particle in the mixed liquid and the stability of the quantum dot may vary depending on the form thereof. It may be necessary to appropriately control the molar ratio of the inorganic particles.

2A is a schematic view showing a quantum dot-inorganic particle aggregate manufactured by the method described with reference to FIG. FIG. 2B is a schematic view showing an enlarged view of FIG. 2A. FIG.

2A and 2B, a quantum dot-inorganic particle aggregate 10 is formed by a capping layer 11b capped by a plurality of quantum dots 11a capped by a first capping layer 11b and a plurality of second capping layers 17b surrounding the quantum dot- And inorganic particles 17a. At this time, the non-polar organic groups in the first capping layer 11b and the non-polar organic groups in the second capping layer 17b may inter-digitate with each other. As a result, stabilized quantum dot-inorganic particle aggregates 10 can be formed.

3 is a cross-sectional view of an optical element according to an embodiment of the present invention.

Referring to FIG. 3, a base substrate 50 having an element region and a peripheral region surrounding the element region is provided. The base substrate 50 may be a silicon substrate, a metal substrate, a ceramic substrate, or a resin substrate. The device region is a region in which a light emitting diode semiconductor chip to be described later is mounted, and the peripheral region may be another region.

The base substrate 50 may have bonding pads 71 and 72 on its device region. A housing 80 having a cavity 80a may be disposed on a peripheral region of the base substrate 50. [ Portions of the bonding pads 71 and 72 may be exposed in the cavity 80a. The housing 80 may be formed of silicon, metal, ceramics, or resin. The base substrate 50 and the housing 80 may be integrally formed without being separated from each other.

The light emitting diode chip C is disposed on one of the bonding pads exposed in the cavity 80a. The light emitting diode chip (C) includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. When the electric field is applied between the n-type semiconductor layer and the p-type semiconductor layer, the light emitting diode chip C emits light while recombining electrons and holes. The light emitting diode chip (C) may be any one of GaAlAs type, AlGaIn type, AlGaInP type, AlGaInPAs type, and GaN type. Further, the light emitting diode chip (C) may be a device that emits visible light, ultraviolet light, or infrared light. The n-electrode and the p-electrode of the light emitting diode chip C may be electrically connected to the bonding pads 71 and 72 through the wires W, respectively.

On the other hand, it is possible to provide a dispersion in which quantum dot-inorganic particle aggregates produced by the method described with reference to Fig. 1 are dispersed. The solvent in the dispersion may be toluene, ethanol, or a mixture thereof. A quantum dot (not shown) or a fluorescent material (not shown) may be further included in the dispersion. The dispersion may be mixed with a sealing resin to form a coating solution. The sealing resin may be a curable resin. As an example, the sealing resin may be selected from the group consisting of an epoxy resin, a phenol resin, a polyester, a silicone resin, an acrylate resin, a urethane-acrylate resin and a combination thereof. The sealing resin may be a silicone resin having a low possibility of yellowing.

The light conversion layer 60 may be formed by dotting the coating solution on the light emitting diode chip C. The forming of the photo-conversion layer 60 may further include dipping the coating solution, and then curing the doped coating solution. Dotting of the coating liquid may be performed by using a printing method or a dispensing method.

In the light conversion layer 60, the quantum dot-inorganic particle aggregates may be dispersed. In addition, since the quantum dot-inorganic particle aggregates have the form in which the inorganic particles surround the quantum dots, the quantum dots can be stabilized by the inorganic particles and the quantum efficiency can be maintained even in a high temperature environment when the light emitting diode operates.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

[Experimental Examples; Examples]

Experimental Example 1: Preparation of dispersion of silica nanoparticles

12 g of fumed silica having an average diameter of 11 nm was placed in 400 ml of toluene and dispersed using a stirrer, and 4 g of hexadecyltrimethoxysilane was added thereto. The solution was placed in an ultrasonic bath and ultrasonicated at 70W at 60W. After 4 hours of reaction, 1 g of trimethylmethoxysilane was added and the reaction was continued for 8 hours. Thereafter, the mixture was cooled to room temperature, 400 ml of ethanol was added, and centrifuged to obtain surface-treated silica nanoparticles. The surface-treated silica was dispersed in toluene containing 10 wt% ethanol at a concentration of about 10 mg / ml to prepare a dispersion of silica nanoparticles.

Experimental Example 2: Quantum dot-silica nanoparticle agglomerate preparation

0.35 ml (corresponding to 3.5 mg of silica) of the silica dispersion prepared in Experimental Example 1 was added to 2.5 ml of toluene and heated to about 110 캜 to change it transparently. On the other hand, a CdSe / ZnS core-shell quantum dot having hexadecylamine as a capping layer was dispersed in toluene at a concentration of 25 mg / ml to prepare a quantum dot dispersion. 0.075 ml of the above quantum dot dispersion (corresponding to 1.5 mg of a quantum dot) was added to the heated silica dispersion and stirred to prepare a mixed solution, and then the mixture was cooled to room temperature. Thereafter, the solvent was appropriately removed by using a reduced pressure rotary condenser to obtain a mixed solution of a quantum dot-silica nanoparticle aggregate and a solvent.

Experimental Example 3: Fabrication of light emitting diode having quantum dot-silica nanoparticle agglomerates

The mixed solution of the quantum dot-silica nanoparticle agglomerate and the solvent of Experimental Example 2 was mixed with 0.5 g of silicone resin, and then all of the solvent was removed at room temperature using a rotary vacuum concentrator. 15 mg of the silicone resin containing the quantum dot-silica nanoparticle agglomerates from which the solvent was removed was injected onto a blue light emitting diode and cured at 120 ° C for 10 hours.

Comparative Example 1: Fabrication of light emitting diodes having quantum dots

A CdSe / ZnS core-shell quantum dot having hexadecylamine as a capping layer was dispersed in toluene at a concentration of 20 mg / ml to prepare a quantum dot dispersion. The quantum dot dispersion containing 1.5 mg of quantum dots and 0.5 g of silicone resin were mixed and then the solvent was removed at room temperature using a rotary vacuum concentrator. 15 mg of silicone resin containing a quantum dot was injected onto a blue light emitting diode and cured at 120 캜 for 10 hours.

4 is a TEM photograph of the aggregate of the quantum dot-silica nanoparticles prepared in Experimental Example 2. FIG.

Referring to FIG. 4, the quantum dots are dark dots, and the excess silica nanoparticles are gray dots. As shown in the photograph, it can be seen that the quantum dots are not aggregated with each other, and each of the quantum dots is surrounded by a plurality of silica nanoparticles and aggregated. It can be seen that this corresponds to the schematic diagram shown in Fig.

5 and 6 show photoluminescence (PL) intensities of the LEDs manufactured in Experimental Example 3 and Comparative Example 1 while operating at 60 mA and 3.2 V, respectively, Of the light emission intensity.

Referring to FIGS. 5 and 6, it can be seen that the light emitting intensity according to Experimental Example 3 (FIG. 5) hardly changes with time. On the other hand, it can be seen that the light emission intensity of the light emitting diode according to the comparative example 1 (FIG. 6) is greatly reduced to about 40% after 8 days. From this, in the case of Comparative Example 1, the quantum dots are seen to be damaged by heat with time. However, in Experimental Example 3, the photoluminescence intensity was about 93% even after 12 days. This is because the QDs are surrounded by the silica nanoparticles and the heat resistance is improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

Claims (14)

Quantum dot;
And a plurality of inorganic particles agglomerated outside the quantum dots. The method according to claim 1,
The quantum dot is capped by a first capping layer,
Each of the inorganic particles being capped by a second capping layer. 3. The method of claim 2,
Wherein the first capping layer is a nonpolar organic ligand. The method of claim 3,
Wherein the first capping layer is a layer of a material selected from the group consisting of phosphine oxide, phosphine, amine, organic acid, phosphonic acid, phosphinic acid, thiol, and combinations thereof having a nonpolar organic group . 3. The method of claim 2,
Wherein the second capping layer is a nonpolar organic ligand. 6. The method of claim 5,
Wherein the second capping layer is a layer of material selected from the group consisting of phosphine oxide having a nonpolar organic group, phosphine, amine, organic acid, phosphonic acid, phosphinic acid, thiol, silane, alkoxysilane, Qdots - inorganic particle aggregates. 3. The method of claim 2,
Wherein the first capping layer and the second capping layer are the same or different nonpolar organic ligands,
The non-polar organic group of the first capping layer and the non-polar organic group of the second capping layer inter-digitate with each other. The method according to claim 1,
Wherein the inorganic particles are titanium oxide, silicon oxide, or aluminum oxide. The method according to claim 1,
The quantum dot has a multilayer structure in the form of a single layer or a core-shell,
Each of the layers of the quantum dots may include at least one of CdS, CdO, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, MnS, MnO, MnSe, MnTe, MgO, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, SnO 2, BaO, BaS, BaSe, BaTE, HgO, HgS, HgSe, HgTe, Al2O3, Al2S3, Al2Se3, Al2Te3, Ga2O3, Ga2S3, Ga2Se3, Ga2Te3, In2O3, In2S3, In2Se3, In2Te3, Sn, SnSe, SnTe, PbO, PbO2, PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, Ge, Wherein the quantum dot-inorganic particle aggregate is a material layer selected from the group consisting of: Providing a quantum dot dispersion in which quantum dots are dispersed in a first solvent;
Providing an inorganic particle dispersion in which inorganic particles are dispersed in a second solvent;
Heating the inorganic particle dispersion;
Mixing the quantum dot dispersion and the heated inorganic particle dispersion to form a mixed solution;
And cooling the mixed solution to form a quantum dot-inorganic particle aggregate, thereby forming a quantum dot-inorganic particle aggregate. 11. The method of claim 10,
The quantum dot is capped by a first capping layer,
Wherein each of the inorganic particles is capped by a second capping layer. 11. The method of claim 10,
Wherein the first solvent is a nonpolar solvent and the second solvent is also a nonpolar solvent. 11. The method of claim 10,
Wherein the first solvent is a nonpolar solvent and the second solvent is a mixed solvent of a nonpolar solvent and a polar solvent. 11. The method of claim 10,
Wherein the molar ratio of the quantum dots to the inorganic particles in the mixed liquid is 1: 4 to 1:12.

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