KR101793515B1 - Manufacturing method of molybdenum disulfide nanoflake - Google Patents

Abstract

The present invention relates to a method for producing molybdenum disulfide nanoflake, and more particularly, to a method for producing molybdenum disulfide nanoflake which forms molybdenum disulfide disulfide on the promoter layer by coating a promoter layer on the substrate.

Description

Technical Field [0001] The present invention relates to a molybdenum disulfide nanoflake,

The present invention relates to a method for producing molybdenum disulfide nanoflake, and more particularly, to a method for producing molybdenum disulfide nanoflake which forms molybdenum disulfide disulfide on the promoter layer by coating a promoter layer on the substrate.

Graphene, in which hexagonal honeycomb-shaped carbon atoms are arranged, is a typical two-dimensional material. Graphene is more than 200 times stronger than steel, more than twice as high as diamond, 100 times more conductive than copper, and 100 times more electrons than silicon. This mechanical, thermal and electrical property of graphene is due to the electronic structure of graphene without energy gap.

Paradoxically, however, graphene without such a bandgap exhibits the characteristics of semi-metals rather than semiconductors, and is becoming a major barrier to transistor application. Therefore, graphene nanoribbons or graphene layers capable of forming energy bandgap in graphene for transistor application have been actively studied. However, only limited band gap of about 0.4 eV is possible, and a band gap is formed There is a problem that the mobility decreases sharply and there is a limit to the practical application.

In order to solve these problems, attention has been paid to two-dimensional materials other than graphene, and recently interest in transition metal chalcogen compounds such as molybdenum disulfide is rapidly increasing.

Molybdenum disulfide (MoS ₂ ) is one of the transition metal chalcogenide materials having a layered structure similar to graphene. It has an indirect bandgap of about 1.3 eV in the case of bulk material, but when it is thinned with nano-thick film, It is known to have a direct bandgap, and studies for manufacturing molybdenum disulfide nanotubes are actively underway.

On the other hand, there is still a small amount of research to produce molybdenum disulfide nanoflake capable of maximizing the physical / chemical change of the electrochemical reaction occurring on the surface or the edge due to its wide surface area.

To date, there have been chemical and mechanical methods for producing molybdenum disulfide nanoflake. The flake synthesis method using the chemical stripping method may have a characteristic deterioration due to the chemical treatment, and there is a limitation in application such as an electric element by a simple physical defect with the substrate. Further, as a flake synthesis method using a mechanical stripping method, a technique of vertically aligning is almost impossible, and there is also a problem in mass production. On the other hand, when a flat two - dimensional structure is synthesized by using a chemical vapor deposition method, defects due to a random seeding site and polycrystallinity may cause problems in uniform thin film synthesis.

Korean Patent Publication No. 10-2015-0015183 (February 10, 2015)

Qian, H. et al., Scientific Reports, 2016, 6, 211171

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for preparing molybdenum disulfide nanoflake by supplying a molybdenum precursor and a sulfur source onto a promoter layer formed on a substrate surface.

The present invention relates to a process for producing molybdenum disulfide nanoflake.

One aspect of the present invention is

a) forming a promoter layer on a substrate surface; And

b) forming a molybdenum precursor and a sulfur source on the surface of the promoter layer to form molybdenum disulfide nanoflake;

And a method for producing the molybdenum disulfide nanoflake.

In one embodiment of the present invention, the promoter layer may include one or more compounds selected from the following formulas (1) to (3).

[Chemical Formula 1]

(2)

(3)

(In the above Formulas 1 to 3,

Z is independently C-R 'or N;

R 'is hydrogen, halogen, a substituted or unsubstituted (C1-C20) alkyl group or a substituted or unsubstituted (C6-C20) aryl group;

R ₁ to R ₁₆ are each independently hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group or a substituted or unsubstituted (C 6 -C 20) aryl group.

In one embodiment of the present invention, the promoter layer may include a compound represented by the following general formula (4).

[Chemical Formula 4]

(Wherein R ₁ to R ₈ and R ₁₇ to R ₂₀ each independently represent hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group, or a substituted or unsubstituted (C 6 -C 20) aryl group to be.)

In an embodiment of the present invention, the steps a) and b) may be performed by any one of a sputtering method, a physical vapor deposition method, a plasma-enhanced chemical vapor deposition method, a thermal chemical vapor deposition method A vapor deposition method, a vapor deposition method, a molecular layer deposition method, an atomic layer deposition method, and a thermal evaporation method.

In one embodiment of the present invention, the molybdenum precursor is not limited to any kind as long as it can deposit molybdenum through various methods. For example, ammonium molybdate tetraborate ((NH ₄ ) ₂ MoS ₄ ) ((NH ₄ ) ₆ Mo ₇ O ₂₄ ), tetramethylammonium tetrapropylammonium molybdate (((CH ₃ ) ₄ N) ₂ MoS ₄ ) and tetraethylammonium tetrapropylammonium tetrafluoroborate (((C ₂ H ₅ ) ₄ N) ₂ MoS ₄ ).

In one embodiment of the present invention, the sulfur source is not limited to the type as long as it can induce the deposition of uniform thickness of molybdenum disulfide nanoflake. For example, vaporized sulfur or hydrogen sulfide (H ₂ S) .

The molybdenum disulfide nanoflake according to the present invention can be produced from a promoter layer with a large area of molybdenum disulfide nanoflurane, and the molybdenum disulfide nanoflake is grown vertically successively from the promoter layer to have excellent crystallinity. Also, the amount of molybdenum disulfide nanoflake produced according to the amount of molybdenum precursor and sulfur source to be flowed, growth temperature, thickness of the impregnated motor layer, and the like can be controlled. The molybdenum disulfide nanoflake produced according to the present invention has an advantage that it can maximize the physical / chemical change of the electrochemical reaction occurring on the surface or the edge due to its wide surface area.

Fig. 1 Image of molybdenum disulfide nanoflake according to the thickness of the promoter layer
FIG. 2 - Transmission electron microscope image of vertically grown molybdenum disulfide nanoflake and molybdenum disulfide film grown horizontally on the surface of the promoter layer
Fig. 3 Image showing the formation of molybdenum disulfide nanoflake depending on the presence or absence of the promoter layer
Figure 4 - Image of molybdenum disulfide nanoflake grown on SiO ₂ surface at various growth temperatures

Hereinafter, a method of preparing the molybdenum disulfide nanoflake according to the present invention will be described in detail with reference to the accompanying drawings and specific examples. It should be understood, however, that the invention is not limited thereto and that various changes and modifications may be made without departing from the spirit and scope of the invention.

Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

In addition, the following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the drawings presented below may be exaggerated in order to clarify the spirit of the present invention. Also, throughout the specification, like reference numerals designate like elements.

Also, the singular forms as used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected."

The process for producing molybdenum disulfide nanoflake according to the present invention comprises

a) forming a promoter layer on a substrate surface; And

b) forming a molybdenum precursor and a sulfur source on the surface of the promoter layer to form molybdenum disulfide nanoflake;

. ≪ / RTI >

The substrate is not limited to the type as long as various deposition methods can be applied, but it is preferable that the substrate has thermal stability in the ALD temperature window. It may also be a transparent substrate, a flexible substrate, or a transparent flexible substrate, but is not limited thereto.

Examples of the substrate include a transparent inorganic substrate such as glass, quartz, sapphire, SiC, or MgO; a transparent substrate such as polyethylene terephthalate (PET), polystyrene (PS), polyimide (PI), polyvinyl chloride A transparent flexible organic material substrate such as PVP or polyethylene or a substrate made of Si, Ge, GaAs, InP, InSb, InAs, AlAs, AlSb, CdTe, ZnTe, ZnS, CdSe, CdSb or GaP have. When a plastic substrate such as PET is used as a substrate for a device, an electronic device can be manufactured as a flexible device.

In the present invention, the promoter layer may include any one or more compounds selected from the following formulas (1) to (3).

[Chemical Formula 1]

(2)

(3)

(In the above Formulas 1 to 3,

Z is independently C-R 'or N;

R 'is hydrogen, halogen, a substituted or unsubstituted (C1-C20) alkyl group or a substituted or unsubstituted (C6-C20) aryl group;

R ₁ to R ₁₆ are each independently hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group or a substituted or unsubstituted (C 6 -C 20) aryl group.

The promoter plays a role of assisting synthesis of molybdenum molybdenum disulfide nanoflake having a single layer or 2 to 5 layer structure when sulfur is vaporized at a high temperature.

In the present invention, the compound of formula (1) is a compound called porphyrin, which is a stable compound having four rings of pyrrole which is a pentagonal substance containing a nitrogen atom and is formed into a gigantic ring, and tetrapyrrole, ≪ / RTI > compounds. Porphyrin has a planar structure because it has 11 double bonds conjugated and satisfies the aromaticity of the " 4n + 2 " Also, porphyrin can synthesize various porphyrin compounds by introducing various functional groups at meso and β-pyrrole positions.

In the present invention, the formula (2) or (3) is a phthalocyanine-based or naphthalocyanine-based aromatic cyclic compound which may contain hetero elements.

In the present invention, the promoter may further include a compound having a structure represented by the following formula (4).

[Chemical Formula 4]

(Wherein R ₁ to R ₈ and R ₁₇ to R ₂₀ each independently represent hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group, or a substituted or unsubstituted (C 6 -C 20) aryl group to be.)

When carbon compounds other than porphyrin, phthalocyanine or naphthalocyanine are used as the promoter, it is difficult to grow vertically aligned molybdenum disulfide nanoflake dislocations. For example, the ratio of sulfur to molybdenum may be different from that of molybdenum disulfide.

In the present invention, the method for depositing the promoter on the substrate in the step a) may be any known deposition method and is not particularly limited. For example, it is preferable to perform the reaction in a chamber capable of thermal evaporation, and it is possible to supply the reactant periodically and further include a rotary vacuum pump or the like for reasons such as inert gas or nitrogen gas for removing excess residue after the reaction It is good to do.

Molybdenum precursor and sulfur source may be supplied to the surface of the promoter layer formed in step a) to form molybdenum disulfide nanoflake.

In the present invention, the molybdenum precursor is not limited to any kind as long as the material can deposit molybdenum through various methods. Examples of the molybdenum precursor include ammonium molybdate tetra (ammonium (NH ₄ ) ₂ MoS ₄ ), ammonium chilled molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O), tetramethylammonium tetraphenyl molybdate ((CH ₃ ) ₄ N) ₂ MoS ₄ ) and tetraethyl ammonium molybdate tetraethyl ammoniumsulfate (((C ₂ H ₅ ) ₄ N) ₂ MoS ₄ ).

In the present invention, the sulfur source is not limited to the type as long as it can induce the deposition of molybdenum disulfide nanoprecite having a uniform thickness. For example, vaporized sulfur, hydrogen sulfide (H ₂ S) and the like can be used.

The method of manufacturing the molybdenum disulfide nanoflake of the present invention is not limited to the vapor deposition method. For example, the method of sputtering, physical vapor deposition, plasma-enhanced chemical vapor deposition, A thermal evaporation method, a thermal chemical vapor deposition method, a molecular layer deposition method, an atomic layer deposition method, and a thermal evaporation method.

In one embodiment of the present invention, the promoter layer may be formed on the surface of the substrate through a thermal deposition process, and the molybdenum disulfide nanoflakes may be formed on the surface of the promoter layer through thermal chemical vapor deposition.

In one embodiment of the present invention, it is preferable to use a thermal evaporator for evaporating the promoter layer and a thermochemical evaporator for growing molybdenum disulfide.

In order to deposit the promoter, a high-purity solid or liquid phase promoter may be used, or a promoter solution in which the promoter is dissolved in an organic solvent may be used. As the organic solvent, any solvent capable of dissolving the promoter can be used without any particular limitation.

The deposition of the promoter may be performed by heating the promoter or the promoter solution in a vacuum to vaporize the promoter and bringing the promoter molecules in a gaseous state into contact with a substrate to be grown. The thickness of the promoter layer may be adjusted according to the amount of the promoter .

The promoter may be easily vaporized by heat-treating the promoter or the promoter solution within a temperature range of 100 ° C to 400 ° C.

When the substrate on which the promoter layer is deposited is placed in a thermochemical vaporizer and molybdenum source including gaseous molybdenum source and sulfur source are supplied and maintained at a high temperature, a molybdenum disulfide layer is grown. At this time, the molybdenum disulfide layer represents a molybdenum disulfide nanoflake grown vertically sequentially in a large area.

The molybdenum disulfide nanoflake according to the present invention can grow the molybdenum disulfide disulfide from the promoter layer deposited on the substrate in a vertical direction in a sequential manner. The molybdenum precursor and the sulfur source amount, the thickness of the promoter layer, The amount of the molybdenum disulfide nanoflake produced by changing the process temperature for growing molybdenum can be controlled.

The thickness of the promoter layer and the growth temperature of the molybdenum disulfide can be changed according to the amount of the molybdenum disulfide nanoflake to be produced. However, the preferable thickness of the promoter layer is 0.5 to 50 nm, the growth temperature of the molybdenum disulfide is 600 to 900 DEG C Lt; RTI ID = 0.0 > 800 C < / RTI > The conditions under which the amount of nanoflake is maximally grown may vary depending on the size and shape of the reactor. However, in the case of the thickness of the promoter of about 0.5 to 2.5 nm and the growth temperature of about 650 to 750 DEG C, .

In addition, the molybdenum disulfide nanoflake produced according to the present invention can maximize the physical / chemical change of the electrochemical reaction occurring on the surface or the edge due to its wide surface area, and can be used as a core element capable of realizing a next generation flexible electronic device .

The thickness and size of the molybdenum disulfide nanoflake produced according to the present invention may vary depending on growth conditions, but the molybdenum disulfide nanoflake has a thickness of about 1 to 10 nm, the size of the molybdenum disulfide nanoflake is several tens nanometers To tens of micros.

Hereinafter, a method of preparing the molybdenum disulfide nanoflake according to the present invention will be described in more detail with reference to Examples. However, the following examples are only illustrative of the present invention in further detail, and the present invention is not limited thereto.

(Example 1)

A substrate (2 cm x 2 cm) having a thickness of 300 nm of SiO ₂ grown on Si was washed with an acetone, ethanol, distilled water, and dried using an ultrasonic washing machine. After placing the heat which is capable of promoting the cleaning substrate deposition reactor, the deposition chamber heat 5,10,15,20-tetrakis (4-hydroxyphenyl) -21 H, 23 H -porphine (p -THPP; in the formula (4) R ₁ to R ₈ = hydrogen, R ₁₇ to R ₂₀ = 4-hydroxyphenyl) was placed on a hot wire and gasified at 300 ° C. and flowed at a rate of 0.05 Å / s to form a 1.75 nm thick Lt; RTI ID = 0.0 > p- THPP < / RTI >

The thus obtained p -THPP deposited a SiO ₂ substrate and seven ammonium molybdate _{((NH 4) 6 Mo 7} O 24) to a 0.1M SiO ₂ substrate was dispersed in distilled water at a concentration by 30 seconds of spin-coating at 2000 rpm chemical vapor After being prepared in the evaporator chamber, it was provided at the center of the reactor. As the sulfur source, 0.2 g of sulfur powder was placed at the end of the reaction chamber near the gas inlet. The substrate ( p- THPP on SiO ₂ ) to maintain the distance of sulfur and molybdenum source ((NH ₄ ) ₆ Mo ₇ O ₂₄ on SiO ₂ ) to 20 cm and the molybdenum disulfide to grow is a molybdenum source ((NH ₄ ) ₆ Mo ₇ O ₂₄ on SiO ₂ ). As a synthesis condition, molybdenum disulfide nanoflake was synthesized in vertical direction at 1.4 torr and 700 ℃ while flowing 500 sccm of argon (Ar) gas for 5 minutes. The results are shown in Fig. 1 (i). The size and thickness of the nanoflake produced are several nanometers and tens nanometers, respectively.

A transmission electron microscope image of the grown molybdenum disulfide nanoflake is shown in FIG. 2 is an image of a vertically grown molybdenum disulfide nanoflake. At this time, it can be seen that the edge of the flake is formed with about five layers of grown flakes. The bottom image is a transmission electron microscope image of horizontally grown molybdenum disulfide film grown on the surface of the promoter layer. At this time, it can be seen that not only the flakes but also the horizontally grown films attached to the flakes formed a molybdenum disulfide layer having various lattice structures.

(Example 2)

FIG. 1 (ii) shows an image of molybdenum disulfide nanoflake synthesized by conducting the experiment in the same manner as in Example 1, except that the thickness of the promoter layer was changed to 50 nm.

3 shows an image of the molybdenum disulfide nanoflake grown according to the presence or absence of the promoter layer. From this, the molybdenum disulfide nanoflakes are grown only when the promoter layer is present (FIG. 3 (i) The molybdenum disulfide layer was not formed (Fig. 3 (ii)).

(Example 3)

An image of molybdenum disulfide nanoflake grown at various growth temperatures, that is, 600, 700, 800 and 900 ° C, after depositing a 5 nm thick promoter layer on the surface of SiO ₂ was prepared in the same manner as in Example 1, Respectively. The number of molybdenum disulfide nano-flakes was increased when grown at a growth temperature of 700 ° C., but the number of vertically grown molybdenum disulfide nanoflake was significantly decreased when grown at 900 ° C., Only molybdenum disulfide films were observed.

Claims (7)

a) forming a promoter layer comprising at least one compound selected from the following formulas (1) to (3) on the surface of a substrate; And
b) forming a molybdenum precursor and a sulfur source on the surface of the promoter layer to form molybdenum disulfide nanoflake;
≪ / RTI >
[Chemical Formula 1]

(2)

(3)

(In the above Formulas 1 to 3,
Z is independently CR ' or N;
R 'is hydrogen, halogen, a substituted or unsubstituted (C1-C20) alkyl group or a substituted or unsubstituted (C6-C20) aryl group;
R ₁ to R ₁₆ are each independently hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group or a substituted or unsubstituted (C 6 -C 20) aryl group.
delete The method according to claim 1,
Wherein the promoter layer comprises a compound represented by the following general formula (4).
[Chemical Formula 4]

(Wherein R ₁ to R ₈ and R ₁₇ to R ₂₀ each independently represent hydrogen, halogen, a substituted or unsubstituted (C 1 -C 20) alkyl group, or a substituted or unsubstituted (C 6 -C 20) aryl group to be.) The method according to claim 1,
Wherein the steps a) and b) are carried out by any one of evaporation methods selected from sputtering, physical vapor deposition, plasma enhanced chemical vapor deposition, thermochemical vapor deposition, molecular layer deposition, atomic layer deposition and thermal vacuum deposition, wherein the molybdenum disulfide nano- Method of manufacturing flakes. The method according to claim 1,
The molybdenum precursor may be at least one selected from the group consisting of ammonium molybdatesurate ((NH ₄ ) ₂ MoS ₄ ), ammonium quorumolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O), tetramethylammonium tetra ₃ ) ₄ N) ₂ MoS ₄ ) and tetraethyl ammonium molybdate tetraethylammonium disulfide (((C ₂ H ₅ ) ₄ N) ₂ MoS ₄ ). The method according to claim 1,
Wherein the sulfur source is vaporized sulfur or hydrogen sulphide (H ₂ S). The method according to claim 1,
Wherein the molybdenum disulfide nanoflake is vertically aligned molybdenum disulfide nanoflake.

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