KR101719574B1 - Passivated quantum dot and method for manufacturing the same - Google Patents

Abstract

 The disclosed passivated quantum dot manufacturing method includes the steps of: preparing a first solution including a quantum dot having an organic ligand bound to its surface and a nonpolar solvent dispersing the quantum dot; And adding a second solution containing a halogen salt and a polar solvent to the first solution to remove the organic ligand and forming a passivation layer including a halogen salt on the surface of the quantum dots. The content of the halogen compound is 0.001 mol or more based on 1 g of the quantum dot. According to the above method, a highly stable quantum dot can be obtained, and a quantum dot thin film can be formed without a ligand substitution process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to passivation quantum dots,

The present invention relates to quantum dots, and more particularly to passivation quantum dots and a method of manufacturing the same.

Quantum dots are nanoparticles having a size of several tens of nanometers or less, which have semiconductor characteristics, and have properties different from those of bulk particles due to the quantum confinement effect. Specifically, the bandgap varies according to the size of the quantum dot, and the wavelength to be absorbed can be changed. The quantum confinement effect due to the small size exhibits new optical, electrical, and physical characteristics not seen in bulk materials. Therefore, studies have been actively made on a technique for manufacturing photoelectric conversion elements such as solar cells and light emitting diodes using such quantum dots.

Recently, a colloid chemical synthesis method has been used for controlling the size and shape of a quantum dot in a quantum dot. It is difficult to secure the stability of the quantum dot synthesized by such a colloid chemical synthesis method with respect to air exposure, and the quantum dot of a core- It is stable against air exposure, but it is difficult to use for photoelectric conversion elements and the like, and the process is very complicated.

In order to secure the stability of such a quantum dot, a method of forming a ligand on the surface of a quantum dot using an organic compound such as oleic acid is known. However, in this case, in order to form the quantum dot in the form of a thin film (having conductivity), it is necessary to process the step of exchanging the quantum dot particle with a ligand having a relatively short length after coating it on the substrate.

Such a ligand exchange process degrades process efficiency and limits application of quantum dots. In addition, cracks generated internally due to thin film volume shrinkage during ligand exchange can degrade the quality of quantum dot thin films.

The technical object of the present invention is to provide a quantum dot that can be applied to a thin film forming process without a ligand exchange process as well as securing stability against air exposure.

Another technical problem of the present invention is to provide a method of manufacturing the quantum dot.

According to another aspect of the present invention, there is provided a method of fabricating a passivated quantum dot comprising: preparing a first solution including a quantum dot having an organic ligand bound to its surface and a nonpolar solvent dispersing the quantum dot; And adding a second solution containing a halogen salt and a polar solvent to the first solution to remove the organic ligand and forming a passivation layer including a halogen salt on the surface of the quantum dots. The content of the halogen compound is 0.001 mol or more based on 1 g of the quantum dot.

In one embodiment, the step of preparing the first solution comprises reacting the first precursor with an organic acid and reacting the reactant of the first precursor and the organic acid with the second precursor.

In one embodiment, the first precursor comprises at least one of a Group 12 element, a Group 13 element, and a Group 14 element.

In one embodiment, the second precursor comprises at least one of a Group 15 element and a Group 16 element.

In one embodiment, the organic acid comprises oleic acid.

In one embodiment, the halogen salt comprises at least one of bromine and iodine.

In one embodiment, the volume ratio of the polar solvent to the non-polar solvent is 0.3: 1 or greater.

In one embodiment, the nonpolar solvent comprises a hydrocarbon.

In one embodiment, the polar solvent comprises an alcohol.

The quantum dot according to an embodiment for realizing another object of the present invention includes a group 13-group-15 group compound, a group 12 -16 group compound or a group 14 -16 group compound, Plane and the {111} plane are passivated by the halogen salt.

In one embodiment, the diameter of the quantum dot is 1 to 20 nm.

In one embodiment, the halogen salt comprises iodine or bromine.

According to the present invention, the surface of the quantum dot particles can be entirely passivated, which can greatly improve the stability of the quantum dot particles, especially the atmospheric stability.

In addition, since the quantum dots are in a state in which the organic ligands are removed, there is no need to undergo a ligand replacement process in the course of forming the quantum dot thin film, so that not only the process can be simplified but also the stress due to the thin film generated in the ligand replacement process Can be prevented / reduced.

FIG. 1 is a flowchart illustrating a method of manufacturing a quantum dot according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram showing a step of removing an organic ligand and forming a halogen passivation layer in the method of manufacturing a quantum dot according to an embodiment of the present invention.
FIG. 3A is a graph showing FTIR (Fourier Transform Infrared Spectroscopy) spectra of the quantum dots of Example 1 and Comparative Example 1. FIG.
FIG. 3B is a graph showing an XPS (X-ray photoelectron spectroscopy) spectrum (Pb 4f) of the quantum dots of Example 1 and the quantum dots of Comparative Example 1. FIG.
4 is a graph showing 1 H-NMR (Nuclear Magnetic Resonance) spectra of Comparative Examples 1 and 2.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

A method of fabricating a quantum dot according to an embodiment of the present invention includes forming a quantum dot coupled with an organic ligand and providing a polar solvent and a halogen compound to remove the ligand and form a halogen passivation layer on the surface of the quantum dot .

FIG. 1 is a flowchart illustrating a method of manufacturing a quantum dot according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing a step of removing an organic ligand and forming a halogen passivation layer in the method of manufacturing a quantum dot according to an embodiment of the present invention.

Referring to FIG. 1, the first precursor is reacted with an organic acid (S10). Specifically, the first precursor and the organic acid are dispersed in a solvent. For example, the first precursor may comprise a Group 12 element, a Group 13 element, or a Group 14 element.

For example, a first precursor comprising a Group 12 element may be selected from the group consisting of cadmium acetate dihydrate, dimethyl cadmium, diethyl cadmium, cadmium acetate, Cadmium acetylacetonate, Cadmium acetylacetonate hydrate, Cadmium iodide, Cadmium bromide, Cadmium chloride, Cadmium chloride hydrate, Cadmium acetylacetonate hydrate, Cadmium acetylacetonate hydrate, Cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium nitrate tetrahydrate, cadmium oxide, cadmium perchlorate, cadmium perchlorate, Cargo (Cadmium perchlorate hexahydrate), Cadmium phosphide (Cadmi cadmium naphthenate, cadmium stearate, dimethyl zinc, diethyl zinc, zinc acetate, zinc phosphite, zinc phosphite, cadmium sulfate, Cadmium sulfate, Cadmium naphthenate, Zinc acetate dihydrate, Zinc acetylacetonate, Zinc acetylacetonate hydrate, Zinc iodide, Zinc bromide, Zinc chloride, ), Zinc fluoride, zinc fluoride tetrahydrate, zinc carbonate, zinc cyanide, zinc nitrate, zinc nitrate hexahydrate ( Zinc nitrate hexahydrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc perchlorate, Zinc perchlorate hexahydrate, Zinc sulfate, Diphenyl zinc, Zinc naphthenate, Zinc stearate, Mercury acetate, Mercury iodide, mercury bromide, mercury chloride, mercury fluoride, mercury cyanide, mercury nitrate, mercury nitrate monohydrate, Mercury nitrate monohydrate, mercury oxide, mercury perchlorate, mercury perchlorate tetrahydrate, mercury perchlorate trihydrate, mercury sulfate, dimethyl mercury Dimethyl mercury, diethyl mercury, diphenyl mercury, mercury sulfate, mercury triflate, And the like meten sulfonate (Mercury trifluoromethanesulfonate), methylmercury chloride (Methylmercury chloride), methylmercury iodide (Methylmercury iodide), phenyl mercury acetate (Phenylmercury acetate), phenyl mercury chloride (Phenylmercury chloride). These may be used alone or in combination.

For example, a first precursor comprising a Group 13 element may be selected from the group consisting of aluminum acetate, aluminum iodide, aluminum bromide, aluminum chloride, aluminum chloride hexahydrate aluminum chloride hexahydrate, aluminum fluoride, aluminum nitrate, aluminum oxide, aluminum perchlorate, aluminum carbide, aluminum stearate, Aluminum sulfate, di-i-butylaluminum chloride, diethylaluminum chloride, tri-i-butylaluminum, triethyl aluminum Triethylaluminum), triethyl (tri-sec-butoxy) dialuminium, tri Gallium arsenate, gallium acetylacetonate, gallium chloride, gallium fluoride, gallium fluoride trihydrate, gallium oxide, gallium nitride, gallium arsenide, gallium arsenide, Gallium nitrate, Gallium nitrate hydrate, Gallium sulfate, Gallium iodide, Triethyl gallium, Trimethyl gallium, Indium chloride Indium chloride, indium chloride tetrahydrate, indium oxide, indium nitrate, indium nitrate hydrate, indium sulfate, indium sulfate hydrate, Indium sulfate hydrate, indium acetate, indium acetylacetonate, Te, indium bromide, indium fluoride, indium fluoride trihydrate, trimethyl indium, and the like. These may be used alone or in combination.

For example, a first precursor comprising a Group 14 element may be selected from the group consisting of lead acetate, lead acetate trihydrate, lead bromide, lead chloride, lead fluoride Lead fluoride, lead oxide, lead perchlorate, lead nitrate, lead sulfate, lead carbonate, lead acethylacetonate, lead Lead citrate, lead bromide, lead naphthenate, tin acetate, tin bisacetylacetonate, tin bromide, tin chloride Tin chloride, tin chloride dihydrate, tin chloride pentahydrate, tin fluoride, tin oxide, tin oxide, But are not limited to, tin sulfate, tin iodide, diphenyltin dichloride, germanium tetrachloride, germanium oxide, germanium ethoxide, germanium bromide, Germanium bromide, germanium iodide, tetramethyl germanium, trimethyl germanium chloride, trimethyl germanium bromide and triethyl germanium chloride, etc. . ≪ / RTI > These may be used alone or in combination.

In one embodiment, the organic acid may comprise oleic acid.

In another embodiment, the organic acid comprises a low molecular weight organic acid. The low molecular weight organic acid may be an organic acid having 12 or less carbon atoms. For example, the low molecular weight organic acids may include formic acid, acetic acid, propionic acid, valeric acid, butyric acid, hexanoic acid, Caprylic acid, capric acid, lauric acid and the like may be used. These may be used alone or in combination.

In another embodiment, the organic acid may comprise a mixture of low molecular weight organic acids and oleic acid. When the molar ratio of the low molecular weight organic acid to the oleic acid is excessively large or only the low molecular weight organic acid is used as the organic acid, the diameter of the quantum dot particles may increase and the photoelectric property may be deteriorated. The stability against air exposure may be deteriorated.

In addition, when the mixture of low molecular weight organic acid and oleic acid is used as described above, it is easy to control the size and shape of the quantum dots by controlling the ratio of low molecular weight organic acid and oleic acid.

The organic acid plays an important role in quantum dot growth in the solution reaction process by improving the dispersibility of quantum dots by forming organic ligands on the surface of the quantum dots.

The solvent is an organic solvent. Specifically, the solvent may include a hydrocarbon.

For example, as the hydrocarbon, hexane, dodecane, decane, undecane, tetradecane, hexadecane, 1-hexadecyne, octadecine, diphenyl ether and the like can be used. These may be used alone or in combination.

Examples of the amine include oleyl amine, dodecyl amine, lauryl amine, octyl amine, trioctyl amine, dioctyl amine, Dioctyl amine, hexadecyl amine and the like can be used. These may be used alone or in combination.

Preferably, the solvent uses a non-polar solvent such as hydrocarbon.

The reaction of the first precursor and the organic acid may proceed by heating. For example, the mixture of the first precursor and the organic acid may be conducted at about 80 ° C to about 150 ° C. Preferably, the reaction proceeds in a vacuum or in an inert atmosphere including nitrogen gas, argon gas, and the like.

Degassing may be performed to promote the reaction between the first precursor and the organic acid. The degassing moves the organic acid reaction equilibrium with the first precursor by removing by-products of the reaction, thereby promoting the reaction. The degassing may be carried out for about 1 to 5 hours.

Next, a reaction product of the first precursor and the organic acid is reacted with a second precursor to form a quantum dot having an organic ligand (S20). The second precursor may comprise a Group 15 element or a Group 16 element.

For example, the second precursor may be selected from the group consisting of tri-n-octylphosphine selenide, tri-n-butylphosphine selenide, diethyl diesteranide Diethyl diselenide, dimethylselenide, bis (trimethylsilyl) selenide, selenium-triphenylphosphine (Se-TPP), tri-n-octylphosphine telluride, n-octylphosphine telluride, tri-nbutylphosphine telluride, bis (trimethylsilyl) telluride, tellurium-triphenylphosphine (Te-TPP) Triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), bis (trimethylsilyl) ), Bis (trimethylsilyl) sulfide, trimethylsilyl sulfide, trimethylsilyl sulfur, ammonium sulfide, It may include a rhodium sulfide. These may be used alone or in combination.

The reaction between the reaction product of the first precursor and the organic acid and the second precursor can be carried out by heating. For example, the reaction may be run at about 80 ° C to about 350 ° C, preferably at about 120 ° C to about 300 ° C.

The reaction between the reaction product of the first precursor and the organic acid and the second precursor is preferably terminated rapidly by crystallization. Hexane and ice water may be used for the completion of the reaction.

For example, the quantum dot may include a Group 14-16 group compound, a Group 12-16 group compound, a Group 13-15 group compound, and the like.

For example, the Group 14 to Group 16 compounds may be selected from the group consisting of tin oxide (SnO), tin sulfide (SnS), tin selenide (SnSe), tin tin (SnTe), lead sulfide (PbS), lead selenide (PbSe) (PbTe), germanium oxide (GeO), germanium sulphide (GeS), germanium selenide (GeSe), germanium telenide (GeTe), tin selenium sulfide (SnSeS), tin selenide (SnSeTe) (PbSeTe), lead sulfide (PbSTe), tin lead sulfide (SnPbS), tin lead selenide (SnPbSe), tin lead tinide (PbSe), lead selenide Tin oxide selenide (SnPbTe), tin oxide sulphide (SnOS), tin oxide selenide (SnOSe), tin oxide tin oxide (SnOTe), germanium oxide sulphide (GeOS), germanium oxide selenide (GeOSe), germanium oxide telenide Lead Sulfide selenide may include (SnPbSSe), tin-lead selenium arsenide telephone (SnPbSeTe), tin-lead sulfide telephone arsenide (SnPbSTe) and the like.

For example, the Group 12-Group 16 compounds may be cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium teleonide (CdTe), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telenide Mercury selenide (HgSe), mercury tinide (HgTe), zinc oxide (ZnO), cadmium oxide (CdO), mercury oxide (HgO), cadmium selenium sulfide (CdSeS), cadmium selenium tele (CdSeTe), cadmium sulfide telenide (CdSTe), cadmium zinc sulfide (CdZnS), cadmium zinc selenide (CdZnSe), cadmium sulfide selenide (CdSSe), cadmium zinc telenide (CdZnTe) , Cadmium mercury selenide (CdHgSe), cadmium mercury telenide (CdHgTe), zinc selenium sulfide (ZnSeS), zinc selenide telenide (ZnSeTe), zinc sulfide telenide (ZnSTe), mercury selenium sulfide (HgSeS) (HgSeTe), mercury sulfide telenide (HgSTe), mercury zinc sulfide (HgZnS), mercury zinc selenide (HgZnSe), cadmium zinc oxide (CdZnO), cadmium mercury oxide (CdHgO), zinc mercury oxide (CdSeO), cadmium sulfide oxide (CdSO), mercury selenium oxide (HgSeO), zinc selenide oxide (ZnSeO), zinc telenium oxide (ZnTeO), zinc sulfide oxide (ZnSO), cadmium selenium oxide (HgTeO), mercury sulfide oxide (HgSO), cadmium zinc selenium sulfide (CdZnSeS), cadmium zinc selenium telenide (CdZnSeTe), cadmium zinc sulfide telenide (CdZnSTe), cadmium mercury selenium sulfide (CdHgSeS) Cadmium mercury selenide telenide (CdHgSeTe), cadmium mercury sulfide telenide (CdHgSTe), mercury zinc selenium sulfide (HgZnSeS), mercury zinc selenium tele (HgZnSeTe), mercury zinc sulfide telenide (HgZnSTe), cadmium zinc selenium oxide (CdZnSeO), cadmium zinc telenium oxide (CdZnTeO), cadmium zinc sulfide oxide (CdZnSO), cadmium mercury selenium oxide (CdHgSeO) (CdHgTeO), cadmium mercury sulfide oxide (CdHgSO), zinc mercury selenium oxide (ZnHgSeO), zinc mercury telemonium oxide (ZnHgTeO), zinc mercury sulfide oxide (ZnHgSO), and the like.

For example, the Group 13-Group 15 compound may be selected from the group consisting of gallium phosphorus (GaP), gallium arsenide (GaAs), gallium antimony (GaSb), gallium nitride (GaN), aluminum phosphorus (AlN), aluminum antimony (AlSb), aluminum nitride (AlN), indium phosphosphorus (InP), indium arsenide (InAs), indium antimony (InSb), indium nitride Gallium arsenide nitrides (GaAsN), gallium antimonitride (GaSbN), aluminum phosphorescent arsenide (AlPAs), gallium arsenide nitride (GaN), gallium arsenide nitride (AlP), aluminum phosphorus antimony (AlPSb), aluminum phosphorus nitrides (AlPN), aluminum arsenide nitrides (AlAsN), aluminum antimony nitrides (AlSbN), indium phosphorous arsenide (InPSb), phosphorus Aluminum gallium arsenide (AlGaAs), aluminum gallium antimony (AlGaSb), aluminum gallium arsenide (AlGaAs), aluminum gallium arsenide (AlGaAs), aluminum gallium arsenide Aluminum gallium nitride (AlGaN), aluminum arsenide nitride (AlAsN), aluminum antimonitride (AlSbN), indium gallium phosphide (InGaP), indium gallium arsenide (InGaAs), indium gallium antimony (InGaSb) (InAsN), indium antimony nitrides (InSbN), aluminum indium phosphors (AlInP), aluminum indium arsenide (AlInAs), aluminum indium antimony (AlInSb), indium gallium nitride (InGaN), indium arsenide nitride (AlInN), aluminum arsenide nitrides (AlAsN), aluminum antimony nitrides (AlSbN), aluminum phosphorus nitrides (AlPN), gallium aluminum (GaAlPAs), gallium aluminum phosphorescent antimony (GaAlPSb), gallium indium phosphorous arsenide (GaInPAs), gallium indium aluminum arsenide (GaInAlAs), gallium aluminum phosphorus nitride (GaAlPN) (GaAlAsN), gallium aluminum antimonitride (GaAlSbN), gallium indium phosphorus nitride (GaInPN), gallium indium arsenide nitride (GaInAsN), gallium indium aluminum nitride (GaInAlN), gallium antimony Gallium arsenide phosphorous nitrides (GaAsPPN), gallium arsenide antimony nitrides (GaAsSbN), gallium indium phosphorescent antimony (GaInPSb), gallium indium phosphosulfide nitrides (GaInPN), gallium arsenide phosphide nitrides Indium antimonitride (GaInSbN), gallium phosphorus antimonitride (GaPSbN), indium aluminum phosphors (InAlSiO3), indium aluminum phosphonite (InAlSiO3), indium aluminum phosphonite (InAlN), indium aluminum phosphonite (InAlN), indium aluminum phosphite nitride Niobium antimonitride (InAsSbN), indium aluminum phosphorus antimony (InAlPSb), and the like.

An organic compound is bound to the surface of the quantum dot as a ligand. In this embodiment, the quantum dots may be lead sulfide (PbS) quantum dots combined with oleic acid.

The quantum dot may have a diameter of about 1 to 100 nm, and preferably a diameter of about 1 to 20 nm.

The quantum dot particles have a crystal structure and have a {100} plane and a {111} plane. The {100} and {111} planes have different atomic arrangements. For example, the {100} plane is made of the same metal element and has a polarity, and the {111} plane is made of a metal element and a nonmetal element and can be neutral. The organic ligand binds to a metal element on the {100} plane.

Next, a polar solvent and a halogen compound are provided to the quantum dot to remove the organic ligand, and a halogen passivation layer is formed on the surface of the quantum dot (S30). The halogen passivation layer is formed on the entire surface of the quantum dot. That is, the removal (substantially completely) of the organic ligand occurs.

 The halogen element of the halogen compound reacts with the metal element of the quantum dot to form a passivation layer composed of a halogen salt (M-X, M: a metal element of a quantum dot, and X: a halogen element). The passivation layer may be formed of a monolayer or a multilayer.

For example, a metal element of the {100} plane to which the organic ligand is not bonded may react with a halogen compound to form a passivation layer composed of a halogen salt on the {100} plane. Further, the organic ligand bonded to the {111} plane is removed by the polar solvent, and the metal element of the {111} plane reacts with the halogen compound to form a passivation layer composed of a halogen salt on the {111} plane .

The polar solvent may comprise a protic amine or an alcohol. For example, methanol, ethanol, propanol, butanol and the like may be used, and these may be used singly or in combination. Preferably, a low-molecular alcohol such as methanol, ethanol or the like is used, and more preferably methanol can be used.

The halogen compound is not particularly limited as long as it is capable of generating a halogen ion. However, when considering binding energy, it is preferable that the halogen compound includes bromine or iodine, more preferably iodine. When the halogen element forms a weak bond with the metal element of the quantum dot, the dispersibility in the dispersion medium is lowered and the process applicability is lowered.

For example, the halogen compound may include a halogen salt such as a metal halide, an organic halide and the like. Specifically, tetrabutylammonium bromide, cetyltrimethylammonium bromide, ammonium ammonium bromide, ammonium iodide, potassium bromide, potassium iodide, sodium bromide, sodium iodide, indium bromide indium iodide, and the like can be used. These may be used alone or in combination.

FIG. 2 illustrates a step of removing an organic ligand and forming a halogen passivation layer in a method of manufacturing a quantum dot according to an embodiment of the present invention by exemplifying a PbS quantum dot coupled with an oleic acid ligand.

Referring to FIG. 2, a PbS quantum dot has a {111} plane in which Pb is continuously arranged and a {111} plane in which Pb and S are continuously arranged. The oleic acid ligand (oleate) binds to the {111} plane of Pb. When methanol (polar solvent) and ammonium iodide (halogen compound) are added to the quantum dots, the oleic acid ligand is removed to expose Pb on the {111} plane, which reacts with ammonium iodide to form PbI bonds To form a configured passivation layer.

Removal of the organic ligand and formation of a halogen passivation layer can be determined by the content of the polar solvent and the halogen compound.

When the quantum dots are dispersed in a non-polar solvent, the volume ratio of the polar solvent to the quantum dots relative to the non-polar solvent should be 0.3: 1 or more, preferably 0.3: 1 to 5: 1. When the volume ratio of the polar solvent to the quantum dots of the nonpolar solvent is less than 0.3: 1, the removal of the organic ligand is not completely achieved. If the removal of the organic ligand is not completely performed, the uniformity of dispersion becomes large, so that the separation of the quantum dot particles and the application to a later process are difficult, and a ligand process is required in forming a thin film, and the object of the present invention can not be achieved. When the volume ratio of the polar solvent to the quantum dots of the nonpolar solvent is more than 5: 1, the concentration of the halogen compound may be lowered and the formation of the passivation layer may be difficult.

The content of the halogen compound is preferably 0.001 mol or more with respect to 1 g of the quantum dot. When the content of the halogen compound is less than 0.001 mol per 1 g of the quantum dots, the passivation layer is not completely formed and oleic acid is recombined. For example, the content of the halogen compound may be 0.001 mol to 0.1 mol based on 1 g of the quantum dot.

Next, to precipitate the quantum dots, a nonpolar solvent is added to the solution containing the quantum dots (S40).

As described above, when the volume ratio of the polar solvent to the nonpolar solvent (first nonpolar solvent) for dispersing the quantum dot having the organic ligand is 0.3: 1 or more, the separation of the nonpolar solvent and the polar solvent occurs, So that the precipitation of the quantum dots does not occur.

Therefore, in order to induce mixing of the non-polar solvent and the polar solvent, a non-polar solvent (a second non-polar solvent) is added. Preferably, the second non-polar solvent may be toluene.

After the second nonpolar solvent is added, the quantum dots can be separated by centrifugation, and they can be dispersed in a polar solvent such as a suitable dispersion medium capable of dispersing it, for example, dimethylformamide.

For example, the solution containing the passivated quantum dot can be used to form a quantum dot thin film using conventional methods such as spin coating, spray coating, drop casting, and the like.

According to the embodiment of the present invention, the surface of the quantum dot particles can be entirely passivated, which can greatly improve stability of the quantum dot particles, particularly atmospheric stability.

In addition, since the quantum dots are in a state in which the organic ligands are removed, there is no need to undergo a ligand replacement process in the course of forming the quantum dot thin film, so that not only the process can be simplified but also the stress due to the thin film generated in the ligand replacement process Defects (cracks, etc.) caused by the heat can be prevented / reduced.

Hereinafter, embodiments of the present invention will be described with reference to concrete quantum dot synthesis examples.

Example 1

1.4 ml of oleic acid, and 10 ml of octadecene, 0.46 g of PbO was injected, and the mixture was dissolved at a temperature of 110 ° C and degassed to prepare a precursor solution. After the precursor solution was lowered to 95 ° C, a mixed solution of 210 ml of 6 ml of bis (trimethylsilyl) sulfide and 4 ml of octadecin was introduced in a nitrogen atmosphere. Next, the reaction was quenched using hexane and ice water to form quantum dots.

Subsequently, the step of adding hexane and acetone at a weight ratio of 1: 2 to the solution and centrifugal separation was repeated three times to obtain a PbS quantum dot precipitate. The obtained quantum dots were redispersed in hexane so as to have a concentration of 100 mg / ml.

Subsequently, 1 ml of the PbS quantum dot / hexane solution (100 mg / ml) was mixed with 0.072 g of ammonium iodide / 3 ml of methanol and stirred for 30 seconds. To the stirred solution was added 8 ml of toluene, and the resulting precipitate was redispersed in dimethylformamide.

The diameter of the quantum dots measured by transmission electron microscopy (TEM) was about 3 nm.

Comparative Example 1

1.4 ml of oleic acid, and 10 ml of octadecene, 0.46 g of PbO was injected, and the mixture was dissolved at a temperature of 110 ° C and degassed to prepare a precursor solution. After the precursor solution was lowered to 95 ° C, a mixed solution of 210 ml of 6 ml of bis (trimethylsilyl) sulfide and 4 ml of octadecin was introduced in a nitrogen atmosphere. Next, the reaction was quenched using hexane and ice water to form quantum dots.

Subsequently, the step of adding hexane and acetone at a weight ratio of 1: 2 to the solution and centrifugal separation was repeated three times to obtain a PbS quantum dot precipitate. The obtained quantum dots were redispersed in hexane so as to have a concentration of 100 mg / ml.

The diameter of the quantum dots measured by transmission electron microscopy (TEM) was about 3 nm.

Comparative Example 2

1.4 ml of oleic acid, and 10 ml of octadecene, 0.46 g of PbO was injected, and the mixture was dissolved at a temperature of 110 ° C and degassed to prepare a precursor solution. After the precursor solution was lowered to 95 ° C, a mixed solution of 210 ml of 6 ml of bis (trimethylsilyl) sulfide and 4 ml of octadecin was introduced in a nitrogen atmosphere. Next, the reaction was quenched using hexane and ice water to form quantum dots.

Subsequently, the step of adding hexane and acetone at a weight ratio of 1: 2 to the solution and centrifugal separation was repeated three times to obtain a PbS quantum dot precipitate. The obtained quantum dots were redispersed in hexane so as to have a concentration of 100 mg / ml.

Subsequently, 1 ml of the PbS quantum dot / hexane solution (100 mg / ml) was mixed with 0.0055 g of ammonium iodide / 0.25 ml of methanol and stirred for 30 seconds. To the stirred solution was added hexane and acetone at a weight ratio of 1: 2, centrifuged and the resulting precipitate was re-dispersed in hexane.

 The diameter of the quantum dots measured by transmission electron microscopy (TEM) was about 3 nm.

FIG. 3A is a graph showing FTIR (Fourier Transform Infrared Spectroscopy) spectra of the quantum dots of Example 1 and Comparative Example 1. FIG. FIG. 3B is a graph showing an XPS (X-ray photoelectron spectroscopy) spectrum (Pb 4f) of the quantum dots of Example 1 and the quantum dots of Comparative Example 1. FIG. Specifically, in Fig. 3A, PbS-Iodine represents the FTIR spectrum of the quantum dot of Example 1 treated with ammonium iodide, and PbS-OA represents the FTIR spectrum of the quantum dot of Comparative Example 1 combined with oleic acid. In FIG. 3B, PbS-Iodine in 3a represents the Pb 4f XPS spectrum of the quantum dot of Example 1 treated with ammonium iodide, and PbS-OA represents the Pb 4f XPS spectrum of the quantum dot of Comparative Example 1 combined with oleic acid .

Referring to FIG. 3A, the FTIR spectrum of the quantum dot of Comparative Example 1 shows peaks showing the binding of oleic acid, but the FTIR spectrum of the quantum dot of Example 1 shows that no such peaks are found. 3B, Pb 4f of the quantum dot of Example 1 has a binding energy larger than that of Pb 4f of the quantum dot of Comparative Example 1, which indicates that the Pb-I bond forming the passivation layer has a binding energy Lt; RTI ID = 0.0 > Pb-O < / RTI > which is a bond with the ligand. From these experimental results, it can be confirmed that the organic ligand of the quantum dot can be removed and the passivation layer can be formed according to the embodiment of the present invention.

4 is a graph showing 1 H-NMR (Nuclear Magnetic Resonance) spectra of Comparative Examples 1 and 2. Specifically, a graph A on the left side shows a 1 H-NMR spectrum of a quantum dot of Comparative Example 1, and a graph B on the right side shows a 1 H-NMR spectrum of a quantum dot of Comparative Example 2.

Referring to Fig. 4, in both 1H-NMR spectra of the quantum dots of Comparative Example 1 and 1H-NMR spectra of the quantum dots of Comparative Example 2, peaks were observed between 5 and 6, which is a peak corresponding to the vinyl group of the oleic acid ligand . Therefore, even if a halogen compound is provided to the quantum dot bound to the organic ligand, it can be understood that the organic ligand can not be removed when the specific concentration, for example, the content of the halogen compound is less than 0.001 mol (mol) have.

INDUSTRIAL APPLICABILITY The present invention can be applied to various electronic devices using quantum dots, solar cell transistors, display devices, light sources, and the like.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. You will understand.

Claims (12)

Preparing a first solution comprising a quantum dot having an organic ligand bound to its surface and a nonpolar solvent dispersing the quantum dot; And
A second solution containing a halogen compound and a polar solvent is added to the first solution to remove the organic ligand to form a passivation layer containing a halogen salt on {100} and {111} planes of the quantum dots ≪ / RTI >
Wherein the content of the halogen compound is 0.001 mol or more based on 1 g of the quantum dots and the volume ratio of the polar solvent to the non-polar solvent is 0.3: 1 to 5: 1. 2. The method of claim 1, wherein preparing the first solution comprises:
Reacting the first precursor with an organic acid; And
Reacting a reactant of said first precursor and an organic acid with a second precursor. ≪ RTI ID = 0.0 > 11. < / RTI > The passivated quantum dot manufacturing method according to claim 2, wherein the first precursor includes at least one of Group 12 element, Group 13 element, and Group 14 element. The passivated quantum dot manufacturing method according to claim 2, wherein the second precursor includes at least one of a Group 15 element and a Group 16 element. 3. The method of claim 2, wherein the organic acid comprises oleic acid. The passivated quantum dot of claim 1, wherein the halogen salt comprises at least one of bromine and iodine. delete The method of claim 1, wherein the nonpolar solvent comprises hydrocarbon. 9. The method of claim 8, wherein the polar solvent comprises an alcohol. delete delete delete

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