Two-dimensional nanosheet-metal halide composite and method for manufacturing same

Abstract

One embodiment of the present invention provides a two-dimensional nanosheet-metal halide composite and a method for manufacturing the same. According to one embodiment of the present invention, graphene nanosheets can be efficiently produced simultaneously with the synthesis of nanocrystals, and the systematic size and shape of the metal halide nanocrystals can be controlled by varying the type of ligand introduced in the manufacturing method.

Description

Technology Field

[0001] The present invention relates to a method for producing a metal halide simultaneously with the exfoliation of a two-dimensional material and a two-dimensional nanosheet-metal halide composite produced thereby. Background Technology

[0002] Among conventional graphene manufacturing methods, physical methods offer excellent physical properties as they allow for a very simple separation of graphene from graphite without generating defects; however, they present problems such as difficulty in producing single-layer graphene and the occurrence of restacking or aggregation after production, resulting in very low dispersibility and / or stability in colloidal form.

[0003] In the case of chemical methods, graphite is oxidized using a strong oxidizing agent, and then graphene oxide is produced through physical methods. Although single-layer graphene oxide can be obtained because oxidized graphene is easily dispersed in water, it cannot be reduced 100% when treated with a reducing agent, resulting in the production of reduced graphene oxide with many defects in graphene properties, and also causing problems such as re-aggregation.

[0004] Two-dimensional nanomaterials, which form a crystal structure in a two-dimensional plane, are a source technology with great potential for application in various industrial fields and are materials in which the atomic arrangement is two-dimensional within a single atomic layer. Representative examples include graphene, transition metals, halogen compounds, black phosphorus, and hexagonal boron nitride.

[0005] In particular, among two-dimensional nanomaterials, graphene is being extensively studied due to its excellent electrical conductivity, which is more than 100 times that of copper, as well as its excellent thermal conductivity and mechanical properties, which are more than 10 times that of copper or aluminum. Due to these characteristics of graphene, much research is currently being conducted on the fabrication of two-dimensional nanomaterial thin films for application in semiconductors or electronic products.

[0006] Two-dimensional nanomaterials can exhibit very new physical and device characteristics by forming heterojunctions with existing low-dimensional materials, such as one-dimensional and two-dimensional nanomaterials like quantum dots and nanowires, and even three-dimensional nanomaterials. They can be stacked in multiple layers or have various electrical and optical devices, such as memory, photosensors, energy devices, and computing devices, formed on each layer, and can be fabricated into a single three-dimensional vertical structure by stacking layers, thus offering a wide range of applications.

[0007] In addition, two-dimensional nanomaterials have the advantage of being very thin with a thickness of just one atomic layer, allowing for high integration of semiconductor devices, and exhibit excellent device performance such as fast switching due to their much higher charge transfer speed compared to silicon.

[0008] However, semiconductors realized with two-dimensional nanomaterials are difficult to control electrical properties compared to silicon semiconductors, making it difficult to achieve device properties comparable to silicon devices, and there is still a lack of research on applying doping, which is essential for controlling semiconductor properties.

[0009] Research on the fundamental physical properties of two-dimensional semiconductors has mainly involved growing or exfoliating single crystals to create and use two-dimensional semiconductors, but the size of such exfoliated two-dimensional semiconductor single crystals is at the micrometer level, which limits their practical application.

[0010] Therefore, the process of fabricating high-quality large-area two-dimensional single-crystal semiconductors using various methods including CVD is of great industrial importance, and inducing the exfoliation of two-dimensional nanomaterials through new materials is also emerging as a new industrial priority.

[0011] For this reason, attempts are being made in various fields to apply the results of synthesis research on halide perovskite nanocrystals to material exfoliation; however, these nanocrystals are difficult to apply in practice due to their toxicity and instability.

[0012] Therefore, unlike perovskite nanocrystals, there is a need to develop manufacturing technologies for metal halides that exhibit greater stability while maintaining optoelectronic capabilities. Prior art literature

[0013] Republic of Korea Published Patent Application No. 10-2020-0074896 The problem to be solved

[0014] The technical problem that the present invention aims to solve is to provide a manufacturing process that includes the growth of metal halides and a two-dimensional nanomaterial exfoliation process simultaneously.

[0015] In addition, the invention provides a metal halide composition for exfoliating two-dimensional nanomaterials capable of exfoliating two-dimensional nanomaterials.

[0016] In addition, the invention provides a two-dimensional nanosheet material in which metal halides subsequently grow to act as a functional support for immobilizing various nanoclusters and nanoparticles.

[0017] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0018] To achieve the above technical objectives, one embodiment of the present invention provides a method for manufacturing a two-dimensional nanosheet-metal halide composite.

[0019] A method for preparing a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention may include the steps of: preparing a two-dimensional material dispersion solution by uniformly dispersing a two-dimensional material in a bulk state in an organic solvent; forming a mixed solution by mixing the two-dimensional material dispersion solution with a metal halide precursor in the presence of two types of ligands; ultrasonically treating the mixed solution in a vacuum atmosphere to exfoliate the two-dimensional material in a bulk state and produce a two-dimensional nanosheet having metal nanoparticles located on its surface; and introducing a solution containing a metal cation compound into the two-dimensional nanosheet having metal nanoparticles located on its surface and reacting to produce a two-dimensional nanosheet-metal halide composite.

[0020] In addition, according to one embodiment of the present invention, the metal halide precursor may include one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2.

[0021] In addition, according to one embodiment of the present invention, the two-dimensional material is graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorus trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, phosphorene, layered double hydroxide (LDH), hexagonal boron nitride (h-BN), graphitic carbon nitride (g-C3N4), molybdenum disulfide (MoS2), tungsten, tungsten diselenide (WSe2), niobium diselenide, It may include one or more selected from the group consisting of NbSe2), Laponite clay, and transition metal oxides.

[0022] In addition, according to one embodiment of the present invention, the two types of ligands may include a first ligand selected from the group consisting of oleic acid, pelargonic acid, and azelaic acid, and a second ligand selected from the group consisting of oleylamine, normal amine, and hexylamine.

[0023] In addition, according to one embodiment of the present invention, the content ratio of the first ligand and the second ligand may be 0.9 to 1.1:0.9 to 1.1 as a molar ratio.

[0024] In addition, according to one embodiment of the present invention, the organic ligand may include one or more selected from the group consisting of mercaptopropionic acid (MPA), cysteamine, mercaptoacetic acid, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and octylphosphinic acid (OPA).

[0025] In addition, according to one embodiment of the present invention, the metal cation may include one or more selected from the group consisting of Cs, Sn, Ge, Sb, Bi, Cu, In, and Ag.

[0026] In addition, according to one embodiment of the present invention, in the step of forming the mixed solution, the content ratio of the metal halide precursor, two types of ligands, and the two-dimensional material dispersion solution in the mixed solution may be 0.3 to 0.5 : 0.8 to 1.2 : 9 to 11 as a molar ratio.

[0027] In addition, according to one embodiment of the present invention, in the step of manufacturing a two-dimensional nanosheet having the metal nanoparticles located on the surface, the ultrasonic treatment may be performed for 10 to 15 minutes.

[0028] In addition, according to one embodiment of the present invention, in the step of manufacturing a two-dimensional nanosheet having the metal nanoparticles located on the surface, the reaction may be performed in a temperature range of 110°C to 180°C.

[0029] In addition, according to one embodiment of the present invention, in the step of preparing the two-dimensional nanosheet-metal halide composite, the reaction may be carried out in a temperature range of 60°C to 80°C.

[0031] To achieve the above technical problem, another embodiment of the present invention provides a two-dimensional nanosheet-metal halide composite.

[0032] The two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention can be manufactured by the method for manufacturing a two-dimensional nanosheet-metal halide composite described above.

[0033] In addition, according to one embodiment of the present invention, the two-dimensional nanosheet may include one or more selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorous trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, and phosphorene.

[0034] In addition, according to one embodiment of the present invention, the metal halide may have a structure in which metal nanoparticles and a halogen material are combined.

[0035] In addition, according to one embodiment of the present invention, the metal halide may include one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2. Effects of the invention

[0036] According to the method for manufacturing a two-dimensional nanosheet-metal halide composite of the present invention, graphene nanosheets can be efficiently produced simultaneously with the synthesis of nanocrystals, and the introduction of a metal cation compound precursor can induce the rearrangement of atoms of metal-based nanocrystals along with changes in microstructure.

[0037] In addition, according to the method for manufacturing a two-dimensional nanosheet-metal halide composite of the present invention, two types of ligands can be used as capping ligands to exfoliate the two-dimensional material, and by varying the types of ligands introduced in the manufacturing method, the systematic size and shape of the metal halide nanocrystals can be controlled.

[0038] Furthermore, metal halides involving a two-dimensional material exfoliation process reduce the band gap depending on the concentration of the two-dimensional material, resulting in a high charge carrier concentration and consequently possessing significant conductivity.

[0039] In addition, the photocurrent response can be selectively controlled by adjusting the content of the two-dimensional material of the present invention.

[0040] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0041] FIG. 1 is a flowchart illustrating a method for manufacturing a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention. FIG. 2 shows an anti-counterfeiting QR code using a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention. FIG. 3 shows an IV curve of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention, which exhibits photoresponsiveness only at light of a specific wavelength range. FIG. 4 shows a transmission electron microscope (TEM) image of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention. FIG. 5 shows the XPS spectrum of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention. FIG. 6 shows the UV-Vis spectrum of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention. FIG. 7 shows the PL spectrum of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention. Specific details for implementing the invention

[0042] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0043] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0044] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0046] Although conventional physical and chemical methods for separating graphite into graphene are simple, re-aggregation occurs, making it difficult to form a single layer, and the size of the exfoliated two-dimensional semiconductor single crystal is at the micrometer level, which limits its practical application in various electrical and optical devices. Accordingly, the present invention can provide a manufacturing process that includes the growth of a metal halide and a two-dimensional nanomaterial exfoliation process simultaneously.

[0048] Hereinafter, the present invention will be described with reference to the drawings presented in this specification. For reference, the drawings may be partially exaggerated to illustrate the features of the present invention. In such cases, it is preferable to interpret them in light of the entire intent of this specification.

[0050] A method for manufacturing a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention is described.

[0051] A method for preparing a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention is,

[0052] The method may include the steps of: preparing a two-dimensional material dispersion solution by uniformly dispersing a two-dimensional material in a bulk state in an organic solvent (S100); forming a mixed solution by mixing the two-dimensional material dispersion solution with a metal halide precursor in the presence of two types of ligands (S200); ultrasonically treating the mixed solution in a vacuum atmosphere to exfoliate the two-dimensional material in a bulk state and produce a two-dimensional nanosheet with metal nanoparticles located on its surface (S300); and introducing a solution containing a metal cation compound into the two-dimensional nanosheet with metal nanoparticles located on its surface and reacting it to produce a two-dimensional nanosheet-metal halide complex (S400).

[0053] Conventional metal halide nanocrystals, such as perovskites, are immobilized using a support such as a two-dimensional material and utilized in a wide range of applications. However, existing manufacturing processes required an additional step of homogeneously mixing the nanocrystals with a composition acting as a support after the synthesis process. Accordingly, the present invention enables the synthesis of uniform metal halide nanocrystals and their immobilization on a support composed of a two-dimensional material.

[0054] Therefore, the present invention has excellent stability and economic efficiency, which can simplify existing multi-stage processes into a single process (one-pot synthesis), and thus has excellent industrial applicability.

[0056] In the first step, the method may include the step of preparing a two-dimensional material dispersion solution by uniformly dispersing a two-dimensional material in a bulk state in an organic solvent. (S100)

[0057] The above two-dimensional material is graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorus trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, phosphorene, layered double hydroxide (LDH), hexagonal boron nitride (h-BN), graphitic carbon nitride (g-C3N4), molybdenum disulfide (MoS2), tungsten, tungsten diselenide (WSe2), niobium diselenide (NbSe2), It may include one or more selected from the group consisting of laponite clay and transition metal oxides.

[0058] At this time, the above-mentioned two-dimensional material can be any material having a two-dimensional multilayer structure and is not limited to the examples described above.

[0059] In addition, the organic solvent may include octadecene, hexane, toluene, methanol, or ethanol, but may be used without limitation if it is an organic solvent capable of dispersing the aforementioned two-dimensional material.

[0060] At this time, the content of the bulk two-dimensional material added to the organic solvent may be, for example, 0.4 wt%.

[0062] In the second step, the method may include the step of forming a mixed solution by mixing the two-dimensional material dispersion solution with a metal halide precursor in the presence of two types of ligands. (S200)

[0063] The above metal halide precursor may include one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2.

[0064] At this time, the metal halide precursor material can be represented by the following chemical formula 1 or chemical formula 2.

[0065] [Chemical Formula 1]

[0066] APbXn

[0067] [Chemical Formula 2]

[0068] AMXn

[0069] In the above Chemical Formulas 1 and 2,

[0070] A and M are each independently metal cations, such as Cs, Sn, Ge, Sb, Bi, Cu, In, or Ag, X is a halide anion, and n is an integer greater than or equal to 1.

[0071] For example, the above X can be Br, Cl, or I as a halide anion.

[0072] For example, the above chemical formula 1 can be represented as CsPbX3(X = Br, Cl, I), and the above chemical formula 2 can be represented as Cs3Cu2X5(X = Br, Cl, I) or CsCuI3.

[0073] At this time, the above-mentioned halogenated metal may include combinations thereof in addition to the materials described above, but is not necessarily limited thereto.

[0074] In addition, the two types of ligands may include a first ligand selected from the group consisting of oleic acid, pelargonic acid, and azelaic acid, and a second ligand selected from the group consisting of oleylamine, normal amine, and hexylamine.

[0075] The content ratio of the first ligand and the second ligand may be 0.9 to 1.1:0.9 to 1.1 as a molar ratio.

[0076] At this time, when the content ratio of the first ligand and the second ligand is a molar ratio of 0.9 to 1.1:0.9 to 1.1, the systematic size and shape of nanocrystals such as Cs3Cu2I5 can be easily controlled.

[0077] In addition, the organic ligand may include one or more selected from the group consisting of mercaptopropionic acid (MPA), cysteamine, mercaptoacetic acid, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and octylphosphinic acid (OPA).

[0078] In addition, the metal cation may include one or more selected from the group consisting of Cs, Sn, Ge, Sb, Bi, Cu, In, and Ag.

[0079] At this time, the content ratio of the metal halide precursor, two types of ligands, and the two-dimensional material dispersion solution in the above-mentioned mixed solution is characterized as a molar ratio of 0.3 to 0.5 : 0.8 to 1.2 : 9 to 11.

[0080] For example, the content ratio of the metal halide precursor, two types of ligands, and the two-dimensional material dispersion solution can be mixed in a molar ratio of 0.4:1:10.

[0081] If not mixed at the aforementioned molar ratio, the stability of the manufactured nanocrystals in the liquid phase may be reduced.

[0082] At this time, when a mixed solution is formed by mixing the metal halide precursor, two types of ligands, and a two-dimensional material dispersion solution, the metal and the ligands can form a complex.

[0083] At this time, the 0.4 wt% two-dimensional material dispersion solution of the present invention can be mixed with the complex in a volume of 1.5 mL to 2.5 mL, and the physical properties of the metal halide nanocomposite can be controlled according to the content of this dispersion solution.

[0084] In addition, toluene, chloroform, etc. may be used instead of hexane in the step of forming the above mixed solution.

[0085] For example, the hexane (or toluene or chloroform) in the step of forming the above-described mixed solution may be 0.1 mol to 20 mol, but is not necessarily limited thereto, and may be used without limitation as long as it is a material that causes the metal halide precursor to dissolve in the presence of the above-described two-dimensional material dispersion solution and two types of ligands.

[0087] In the third step, the method may include a step of ultrasonically treating the above-mentioned mixed solution in a vacuum atmosphere to exfoliate the bulk two-dimensional material and produce a two-dimensional nanosheet with metal nanoparticles located on the surface. (S300)

[0088] A method for producing a metal halide simultaneously with the exfoliation of a two-dimensional material according to one embodiment of the present invention presents tandem molecular intercalation, a new exfoliation concept that converts a multilayer two-dimensional layered material into a single layer in a colloidal state.

[0089] Tandem molecular intercalation requires tandem Lewis base intercalates. First, a short "initiator" molecule enters the two-dimensional layered material and widens the interlayer spacing. Then, a long "major" molecule enters the gap to widen the spacing to the maximum and can overcome the forces of interlayer interactions in a random mixture of intercalates.

[0090] A single layer of a two-dimensional layered structure material can be obtained through spontaneous exfoliation by the above tandem molecular incurration.

[0091] At this time, the tandem molecular intercalation has the unique advantage of proceeding as a one-step reaction in a safe and mild environment (at room temperature without ultrasonic decomposition or hydrogen generation).

[0092] In addition, according to one embodiment of the present invention, by using a suitable intercalator, two-dimensional layered structural materials such as graphite, graphite analogs, and metal oxides can be successfully formed into single-layer nanostructures.

[0093] At this time, the ultrasonic treatment can be performed in a vacuum atmosphere. The reason for performing the ultrasonic treatment in a vacuum atmosphere is that it can promote intermolecular interactions between metal nanoparticles and graphene nanosheets, facilitate the attachment of nanoparticles to the surface of the nanosheets, and enhance the stability of the attached nanoparticles.

[0094] In addition, the above ultrasonic treatment can be performed in a temperature range of 110°C to 180°C.

[0095] At this time, the reason the ultrasonic treatment is performed in a temperature range of 110°C to 180°C is that if it is performed below 110°C, there may be a problem where the reaction does not start or proceed because the molecular energy is insufficient, and if it is performed above 180°C, aggregation of the two-dimensional nanosheets and metal halides may occur, affecting the interaction between the nanosheets and the metal halides, which may cause the crystal structure to change or hinder the surface growth of the metal halides on the nanosheets.

[0096] Through this, a two-dimensional material in a bulk state can be exfoliated through the ultrasonic treatment of the present invention to produce a single layer of two-dimensional nanosheets with metal nanoparticles located on the surface.

[0097] The present invention enables the efficient and simple production of halide nanocomposites by controlling the reaction temperature, reaction time, and ligand while maintaining the existing hot injection process. Furthermore, since the existing hot injection process is maintained, it has the effect of minimizing cost increases and enabling efficient and simple manufacturing.

[0099] In the fourth step, the method may include the step of introducing a solution containing a metal cation compound into a two-dimensional nanosheet having metal nanoparticles located on its surface and reacting it to produce a two-dimensional nanosheet-metal halide complex. (S400)

[0100] At this time, when a solution containing an organic ligand and a metal cation compound is introduced and reacted with a two-dimensional nanosheet having the metal nanoparticles located on its surface, the organic ligand and the metal cation compound react with the two-dimensional nanosheet to produce a crystalline two-dimensional nanosheet-metal halide complex.

[0101] At this time, the organic ligand may include one or more selected from the group consisting of mercaptopropionic acid (MPA), cysteamine, mercaptoacetic acid, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and octylphosphinic acid (OPA).

[0102] In addition, the metal cation may include one or more selected from the group consisting of Cs, Sn, Ge, Sb, Bi, Cu, In, and Ag.

[0103] In addition, the reaction can be carried out in the temperature range of 60°C to 80°C.

[0105] Next, the method may further include the step of centrifuging the prepared two-dimensional nanosheet-metal halide composite compound and then suspending it in hexane.

[0106] Thus, the present invention allows metal halides to subsequently grow on the two-dimensional nanosheets and be used as a functional support for immobilizing nanoclusters and nanoparticles.

[0107] Accordingly, by the method for manufacturing a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention, a two-dimensional material can be exfoliated and a nanocrystal can be formed simultaneously.

[0108] In addition, in the case of the present invention, metal nanoparticles are fixed between nanosheets to block ππ interactions, thereby preventing restacking of the nanosheets, so a colloidal solution in which single-layer nanosheets are uniformly dispersed can be obtained, and since additional reducing agent treatment is not required, a nanocomposite without physical defects can be obtained.

[0109] In addition, since the present invention does not require separate oxidation and reduction processes, it can prevent structural damage to graphene and degradation of graphene's inherent electrical properties.

[0110] In addition, by not using excessive amounts of stabilizers or organic solvents, disadvantages in product characteristics due to residual impurities can be prevented.

[0111] Furthermore, the nanocomposite obtained according to the present invention can be used as a metal halide composition that can act as a functional support for fixing nanoclusters and nanoparticles.

[0112] In addition, the metal halide nanocrystals produced according to the present invention can control the size, shape, and electrical conductivity of the nanocrystals depending on the added content of graphite.

[0114] A two-dimensional nanosheet-metal halide composite according to another embodiment of the present invention is described.

[0115] A two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention is characterized by being manufactured by the method for manufacturing a two-dimensional nanosheet-metal halide composite described above.

[0116] At this time, the two-dimensional nanosheet-metal halide composite may comprise a two-dimensional nanosheet; and a metal halide located on the surface of the two-dimensional nanosheet.

[0117] At this time, the two-dimensional nanosheet may include one or more selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorous trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, and phosphorene.

[0118] In addition, the metal halide may have a structure in which metal nanoparticles and a halogen material are combined.

[0119] The above metal halide may include one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2, and may include the following chemical formulas 1 and 2.

[0120] [Chemical Formula 1]

[0121] APbXn

[0122] [Chemical Formula 2]

[0123] AMXn

[0124] In the above Chemical Formulas 1 and 2,

[0125] A and M are each independently metal cations, such as Cs, Sn, Ge, Sb, Bi, Cu, In, or Ag, and

[0126] X is a halide anion, and

[0127] n is an integer greater than or equal to 1.

[0128] For example, the above X may be Br, Cl, or I.

[0129] For example, the above chemical formula 1 can be represented as CsPbX3(X = Br, Cl, I), and the above chemical formula 2 can be represented as Cs3Cu2X5(X = Br, Cl, I) or CsCuI3.

[0131] FIG. 2 shows an anti-counterfeiting QR code using a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention.

[0132] Referring to FIG. 2, a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention can be used as a luminescent black ink to develop an anti-counterfeiting strategy based on a QR pattern.

[0133] The designed monochrome (BW)-QR code can be converted into an luminescent (L)-QR code only under a high-energy UV light source.

[0134] Therefore, by implementing different data in BW-QR and L-QR codes, it is possible to distinguish between genuine and counterfeit products.

[0135] Cs3Cu2I5 / graphene nanocomposite pixels absorb illuminated UV light and emit blue light, causing fake pixels to disappear in L-QR codes.

[0136] Since the above BW-QR code can be easily duplicated and forged, the L-QR code can serve as a hidden check to verify authenticity.

[0138] In addition, FIG. 3 shows an IV curve of a Cs3Cu2I5 / graphene nanocomposite according to one embodiment of the present invention, which exhibits photoresponsiveness only at light of a specific wavelength range.

[0139] Figure 3 shows the dependence of the photocurrent response on the wavelength here.

[0140] Because the Cs3Cu2I5 / graphene nanocomposite emits PL with a large Stokes shift in a narrow excitation band, it exhibits a selective photocurrent response for a specific wavelength (290 nm) through photogating.

[0141] This phenomenon may demonstrate that Cs3Cu2I5 / graphene nanocomposite-based microelectrode-based phototransducers (MPTs) can be used as "turn-on" sensors to electrically detect high-energy UV light that is extremely dangerous to human health.

[0143] The present invention will be explained in more detail below through manufacturing examples and experimental examples. These manufacturing examples and experimental examples are solely for the purpose of illustrating the present invention, and the scope of the present invention is not limited by these manufacturing examples and experimental examples.

[0145] Example 1: Cs 3 Cu 2 I 5 / Synthesis of graphene nanocomposite (1.5 mL of 0.04 wt% graphite dispersion, 3.5 mL of ODE added)

[0146] To synthesize the Cs3Cu2I5 / graphene nanocomposite as follows, the hot injection method was used with the assistance of acid-base ligands.

[0147] First, cesium-oleic acid was prepared by degassing a flask containing 2.5 mg of Cs2CO3, 7.5 mL of ODE, and 0.5 mL of OA at 120°C for 10 to 20 minutes.

[0148] The clear solution containing the generated cesium-oleic acid was stored at 70°C for future use.

[0149] Next, to prepare a 0.04 wt% solution of graphite dispersion, 3.2 mg of graphite flakes were mixed into 10 mL of ODE and the solution was sonicated for 1 hour.

[0150] Next, 1.5 mL of the prepared 0.04 wt% graphite dispersion, 7.6 mg of CuI, 0.5 ml of oleic acid, and 0.5 ml of oleylamine were mixed with 3.5 ml of octadecene (ODE) in a 3-neck flask.

[0151] Next, the mixture was heated under vacuum at a temperature of 120°C for 10 to 20 minutes until a dark blue solution was formed, thereby removing air and moisture.

[0152] At this time, the dark blue solution was ultrasonically treated for 10 to 20 minutes to form a dark red solution.

[0153] Next, the temperature of the formed dark red solution was lowered to 70°C, and 0.3 mL of the prepared cesium-oleic acid solution was quickly injected into the reactor.

[0154] Next, the reactor was cooled to an ice bath after 5 seconds.

[0155] Next, the generated product was recovered by centrifugation and redispersed in 10 mol hexane for later use.

[0157] Example 2: Cs 3 Cu 2 I 5 / Synthesis of graphene nanocomposites (0.04wt% graphite dispersion 2mL, (Inject 3mL of ODE)

[0158] In the above Example 1, the above was prepared in the same manner as Example 1, except that 2 mL of the 0.04 wt% graphite dispersion was mixed instead of 1.5 mL, and 3 mL of octadecene (ODE) was mixed instead of 3.5 mL.

[0160] Example 3: Cs 3 Cu 2 I 5 / Synthesis of graphene nanocomposite (addition of 2.5 mL of 0.04 wt% graphite dispersion, 2.5 mL of ODE)

[0161] In Example 1, the same as in Example 1 was prepared except that 2.5 mL of the 0.04 wt% graphite dispersion was mixed instead of 1.5 mL, and 2.5 mL of ODE was mixed instead of 3.5 mL.

[0163] Comparative Example: Excluding graphite dispersion

[0164] It was prepared in the same manner as Example 1, except that the graphite dispersion was not added.

[0166] Hereinafter, an experimental example is described by performing an experiment using the above example and comparative example according to one embodiment of the present invention.

[0167] Specifically, the characteristics of the Cs3Cu2I5 / graphene nanocomposite were measured using transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-Vis), and photoluminescence (PL).

[0169] Experimental Example 1: Transmission Electron Microscopy (TEM) Analysis

[0170] Referring to FIG. 4, a verification experiment for the preparation of a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention will be described.

[0171] In Experimental Example 1, the surface of the Cs3Cu2I5 / graphene nanocomposites prepared in Examples 1, 2, 3, and Comparative Example 1 was observed using a transmission electron microscope.

[0172] As a result, it was found that small nanoparticles with an average diameter of 5.3 nm were formed on the graphene nanosheets.

[0173] In addition, it can be seen that the size and shape of the metal halide vary depending on the graphene content during the synthesis process, and the average width and length of the comparative example are 23.7 nm and 46.1 nm, respectively.

[0174] In addition, it can be seen that the size of metal halides in nanohybrid is inversely proportional to the graphene content.

[0175] In other words, it can be seen that changing the amount of graphene precursor during the synthesis process affects the size and shape of nanocrystals in nanohybrid.

[0177] Experimental Example 2: XPS Spectrum Analysis

[0178] Referring to FIG. 5, a verification experiment for the preparation of a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention will be described.

[0179] In Experimental Example 2, X-ray Photoelectron Spectroscopy (XPS) spectra were measured to analyze the structural change characteristics of the Cs3Cu2I5 / graphene nanocomposite prepared in Example 1.

[0180] In addition, it can be confirmed that the full width at half maximum of the peak increases in the order of Comparative Example 1 < Example 1 < Example 2 < Example 3.

[0181] These results confirm that identical orthorhombic metal halides were obtained under synthesis conditions despite different sizes and shapes.

[0183] Experimental Example 3: UV-Vis Spectroscopic Analysis

[0184] Referring to FIG. 6, a characteristic verification experiment of a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention will be described.

[0185] In Experimental Example 3, UV-Vis spectra were measured to analyze the structural change characteristics of the Cs3Cu2I5 / graphene nanocomposites prepared in Examples 1, 2, 3, and Comparative Example 1.

[0186] As a result, the maximum absorption peak was about 288 nm, and the band gap decreased as the graphene concentration increased.

[0187] In addition, referring to Fig. 2, it can be seen that it can be used as an anti-counterfeiting QR code by using a transducer that can detect only a specific UV light source.

[0189] Experimental Example 4: PL Spectrometer Analysis

[0190] Referring to FIG. 7, a characteristic verification experiment of a two-dimensional nanosheet-metal halide composite according to one embodiment of the present invention will be described.

[0191] In Experimental Example 3, photoluminescence (PL) spectra were measured to determine the photophysical properties of the metal halide / graphene nanocomposites prepared in Examples 1, 2, 3, and Comparative Example 1. As a result, it was confirmed that in Examples 1, 2, and 3, the PL spectra were emitted at approximately 442 nm even though the graphene content was different.

[0192] In addition, the PL intensity was in the order of Example 3 < Example 2 < Example 1 and was lower than that of Comparison Group 1.

[0193] This showed that graphene facilitates non-radiative energy transfer from metal halides.

[0194] The maximum light energy absorption of metal halides / graphene can occur at 286 nm, which falls within the UV wavelength range.

[0196] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0197] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

Claim 1 A method for preparing a two-dimensional nanosheet-metal halide composite, characterized by comprising: a step of preparing a two-dimensional material dispersion solution by uniformly dispersing a two-dimensional material in a bulk state in an organic solvent; a step of forming a mixed solution by mixing the two-dimensional material dispersion solution with a metal halide precursor in the presence of two types of ligands; a step of preparing a two-dimensional nanosheet having metal nanoparticles located on its surface by ultrasonically treating the mixed solution in a vacuum atmosphere to exfoliate the two-dimensional material in a bulk state through tandem molecular intercalation; and a step of preparing a two-dimensional nanosheet-metal halide composite by introducing a solution containing an organic ligand and a metal cation compound into the two-dimensional nanosheet having metal nanoparticles located on its surface and reacting the two-dimensional nanosheet to prepare the two-dimensional nanosheet-metal halide composite. Claim 2 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that the metal halide precursor comprises one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2. Claim 3 In claim 1, the two-dimensional material is graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorus trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, phosphorene, layered double hydroxide (LDH), hexagonal boron nitride (h-BN), graphitic carbon nitride (g-C3N4), molybdenum disulfide (MoS2), tungsten, tungsten diselenide (WSe2), niobium diselenide (NbSe2), A method for preparing a two-dimensional nanosheet-metal halide composite characterized by including one or more selected from the group consisting of laponite clay and transition metal oxides. Claim 4 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that the two types of ligands comprise a first ligand selected from the group consisting of oleic acid, pelargonic acid, and azelaic acid, and a second ligand selected from the group consisting of oleylamine, normal amine, and hexylamine. Claim 5 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 4, characterized in that the content ratio of the first ligand and the second ligand is 0.9 to 1.1:0.9 to 1.1 as a molar ratio. Claim 6 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 1, wherein the organic ligand comprises one or more selected from the group consisting of mercaptopropionic acid (MPA), cysteamine, mercaptoacetic acid, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and octylphosphinic acid (OPA). Claim 7 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that the metal cation comprises one or more selected from the group consisting of Cs, Sn, Ge, Sb, Bi, Cu, In, and Ag. Claim 8 A method for preparing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that, in the step of forming the mixed solution, the content ratio of the metal halide precursor, two types of ligands, and the two-dimensional material dispersion solution in the mixed solution is 0.3 to 0.5 : 0.8 to 1.2 : 9 to 11 as a molar ratio. Claim 9 A method for manufacturing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that, in the step of manufacturing a two-dimensional nanosheet having metal nanoparticles located on a surface, the ultrasonic treatment is performed for 10 to 15 minutes. Claim 10 A method for manufacturing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that, in the step of manufacturing a two-dimensional nanosheet having metal nanoparticles located on its surface, the reaction is performed in a temperature range of 110°C to 180°C. Claim 11 A method for manufacturing a two-dimensional nanosheet-metal halide composite according to claim 1, characterized in that, in the step of manufacturing the two-dimensional nanosheet-metal halide composite, the reaction is performed in a temperature range of 60°C to 80°C. Claim 12 A two-dimensional nanosheet-metal halide composite characterized by being manufactured by the method for manufacturing a two-dimensional nanosheet-metal halide composite of claim 1. Claim 13 A two-dimensional nanosheet-metal halide composite according to claim 12, characterized in that the two-dimensional nanosheet comprises one or more selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), transition metal trichalcogenide (TMTC), metal phosphorous trichalcogenide (MPT), metal monochalcogenide (MMC), black phosphorus, and phosphorene. Claim 14 A two-dimensional nanosheet-metal halide composite according to claim 12, characterized in that the metal halide has a structure in which metal nanoparticles and a halogen material are combined. Claim 15 A two-dimensional nanosheet-metal halide composite according to claim 12, characterized in that the metal halide comprises one or more selected from the group consisting of CuBr, CuCl, CuI, PbBr2, PbCl2, and PbI2.

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