KR20210034961A - Nanoparticle thin film with controlled mechanical and electrical properties and its manufacturing method - Google Patents

Abstract

Disclosed are a nanoparticle thin film with controlled mechanical and electrical properties and a method of manufacturing the same. According to an embodiment of the present invention, a method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, comprises the following steps of: forming a nanoparticle layer by applying, onto a substrate, a solution containing conductive nanoparticles surrounded by a first ligand; forming a nanoparticle layer, in which the first ligand is substituted with a second ligand, by supporting the substrate and the nanoparticle layer in a ligand substitution solution containing the second ligand and a substitution solvent; and manufacturing a nanoparticle thin film from which the second ligand is removed, by supporting the substrate and the nanoparticle layer substituted with the second ligand in a washing solvent.

Description

Nanoparticle thin film with controlled mechanical and electrical properties and its manufacturing method {NANOPARTICLE THIN FILM WITH CONTROLLED MECHANICAL AND ELECTRICAL PROPERTIES AND ITS MANUFACTURING METHOD}

The present invention relates to a nanoparticle thin film with controlled mechanical and electrical properties and a method of manufacturing the same.

Colloidal nanoparticles have attracted considerable interest in a variety of fields such as electronics, optoelectronics, photovoltaic devices and bio-related sensor applications due to their simple and large-scale fabrication as well as being able to precisely control their properties according to size, shape and composition .

Colloidal nanoparticles are synthesized by being surrounded by a ligand, which is an organic material, and are stable, but a ligand having a long chain length increases the distance between particles and provides insulation by preventing efficient electron transfer between particles.

Therefore, extensive studies have been conducted to replace a ligand with a long chain length with a ligand with a short chain length.

According to such a ligand substitution process, electron transport of the nanoparticle film may be improved, and properties may be improved through a doping effect and energy level modulation.

Most of the ligand vulgaris process is performed by a solid-state ligand substitution method, and can be divided into a ligand substitution step and a washing step.

In this sequential process, the solvent is very important, for example, in order to access the surface of the nanoparticles and displace the original ligand during the ligand substitution step, the target ligand molecule must be disconnected from the solvent molecule.

In addition, in order to remove or control the ligand on the nanoparticle surface during the cleaning step, the solvent molecule must interact with the ligand molecule.

Thus, the ligand substitution step and washing step are greatly influenced by solvent properties such as polarity or steric hindrance.

Nevertheless, most of the ligand substitution process was performed simply using a conventional solvent such as methanol or acetonitrile, and there was no research on this.

In addition, the replacement solvent and the cleaning solvent were not separated in the ligand replacement process, and the effect of the replacement solvent and the cleaning solvent on the nanoparticle thin film properties was not focused.

Korean Patent Publication No. 10-0927204, "Method of manufacturing a nano-porous silica airgel thin film" Republic of Korea Patent Publication No. 10-2017-0117000, "High-sensitivity sensor having a conductive thin film containing cracks and its manufacturing method"

An embodiment of the present invention is a nanoparticle with controlled mechanical and electrical properties capable of manufacturing a nanoparticle thin film with a controlled resistance and a gauge factor of the nanoparticle thin film according to various types of the replacement solvent and washing solvent included in the ligand replacement solution. It is intended to provide a method of manufacturing a thin particle film.

An embodiment of the present invention is a method of manufacturing a nanoparticle thin film in which the degree of crack formed on the surface of the nanoparticle thin film is controlled according to the polarity of the substitution solvent, and mechanical and electrical properties capable of controlling the resistance and gauge factor of the nanoparticle thin film are controlled. I want to provide.

In an embodiment of the present invention, the composition of the substituted ligand on the surface of the conductive nanoparticles is adjusted according to the polarity of the cleaning solvent, so that the resistance and the gauge factor of the nanoparticle thin film can be controlled. I want to provide a way.

An embodiment of the present invention is to provide a method of manufacturing a nanoparticle thin film in which mechanical and electrical properties capable of controlling the resistance and gauge factor of the nanoparticle thin film according to the ligand substitution time of the conductive nanoparticles are adjusted.

An embodiment of the present invention is to provide a method of manufacturing a nanoparticle thin film in which mechanical and electrical properties capable of controlling the resistance and gauge factor of the nanoparticle thin film according to the cleaning time of the ligand-substituted nanoparticle thin film.

An embodiment of the present invention is to provide a nanoparticle thin film with controlled mechanical and electrical properties in which the prepared nanoparticle thin film can be used as an electrode when the polarity of the replacement solvent is low and the polarity of the washing solvent is high.

An embodiment of the present invention is to provide a nanoparticle thin film with controlled mechanical and electrical properties that can use the prepared nanoparticle thin film as an active layer when the polarity of the replacement solvent is high and the polarity of the washing solvent is low.

The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to the present invention includes forming a first nanoparticle layer by applying a solution containing conductive nanoparticles surrounded by a first ligand on a substrate; Forming a second nanoparticle layer in which the first ligand is substituted with the second ligand by supporting the substrate and the first nanoparticle layer in a ligand substitution solution containing a second ligand and a substitution solvent; And preparing a nanoparticle thin film from which the second ligand has been removed by supporting the substrate and the second nanoparticle layer in a cleaning solvent.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the resistance and the gauge factor of the nanoparticle thin film are adjusted according to the time for substituting the first ligand with the second ligand. Can be.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the time for substituting the first ligand with the second ligand may be 10 seconds to 120 seconds.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the gauge factor of the nanoparticle thin film may be adjusted according to the time for removing the second ligand.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the time for removing the second ligand may be 10 seconds to 120 seconds.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the resistance of the nanoparticle thin film may be adjusted to 6.37x10 ^{-6 Ωcm to 3.1Ωcm.}

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the gauge factor of the nanoparticle thin film may be adjusted to 3.1 to 400.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the substitution solvent may be at least one of methanol, ethanol, and isopropanol.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the washing solvent may be at least one of methanol, ethanol, and isopropanol.

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the first ligand is TOPO (trioctylphosphineoxide), octadecanol, oleic acid, and oleylamine. It may contain at least any one of (oleylamine).

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the second ligand is MPA (3-mercaptopropionic acid), EDT (1,2-ethanedithiol), EDA (ethylenediamine), sulfur ions (S ^2-), chloride ion (Cl ^-), bromide ion (Br ^-), thiocyanate ion (SCN ^-), iodine ion (I ^-), disulfide ion (HS ^-), tellurium ions may include at least one of a (Te ^2-), hydroxide ions (OH ^-), boric tetrafluoride ion (BF ₄ ^{- -)} and six hexafluorophosphate ion (PF _6).

According to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, the conductive nanoparticles are gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum ( It may contain at least one of Pt), nickel (Ni), tungsten (W), and iron (Fe).

The nanoparticle thin film manufactured according to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention includes a conductive nanoparticle surrounded by a first ligand and a ligand substitution solution containing a second ligand and a substitution solvent. In the nanoparticle thin film comprising conductive nanoparticles in which the first ligand is substituted with the second ligand and the second ligand is removed using a washing solvent, the substitution solvent is isopropanol and the washing solvent is It is methanol, and the nanoparticle thin film is used as an electrode because the conductive nanoparticles are concentrated, and the resistance of the nanoparticle thin film used as the electrode is 6.37x10 ^-6 Ωcm to 8.03x10 ^-6 Ωcm.

The nanoparticle thin film manufactured according to the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention includes a conductive nanoparticle surrounded by a first ligand and a ligand substitution solution containing a second ligand and a substitution solvent. In the nanoparticle thin film comprising conductive nanoparticles in which the first ligand is substituted with the second ligand and the second ligand is removed using a washing solvent, the substitution solvent is methanol and the washing solvent is It is isopropanol, the nanoparticle thin film is used as an active layer including cracks on the surface, and the resistance of the nanoparticle thin film used as the active layer is characterized in that 0.7Ωcm to 3.1Ωcm.

According to an embodiment of the present invention, it is possible to prepare a nanoparticle thin film in which the resistance of the nanoparticle thin film and a gauge factor are adjusted according to various types of the substitution solvent and washing solvent included in the ligand substitution solution.

According to an embodiment of the present invention, the degree of crack formed on the surface of the nanoparticle thin film is controlled according to the polarity of the substitution solvent, so that the resistance and the gauge factor of the nanoparticle thin film can be adjusted.

According to an embodiment of the present invention, the composition of the substituted ligand on the surface of the conductive nanoparticles is adjusted according to the polarity of the cleaning solvent, so that the resistance and the gauge factor of the nanoparticle thin film can be adjusted.

According to an embodiment of the present invention, the amount of substitution of the ligand on the surface of the conductive nanoparticle is controlled according to the ligand substitution time of the conductive nanoparticle, so that the resistance and the gauge factor of the nanoparticle thin film can be adjusted.

According to an exemplary embodiment of the present invention, the amount of removal of the ligand on the surface of the conductive nanoparticle is controlled according to the cleaning time of the nanoparticle thin film in which the ligand is substituted, so that the resistance and the gauge factor of the nanoparticle thin film can be adjusted.

According to an embodiment of the present invention, when the polarity of the replacement solvent is low and the polarity of the washing solvent is high, the prepared nanoparticle thin film may be used as an electrode.

According to an embodiment of the present invention, when the polarity of the replacement solvent is high and the polarity of the washing solvent is low, the prepared nanoparticle thin film may be used as an active layer.

1 is a flow chart showing a method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention.
2 is a schematic diagram showing an enlarged view of a nanoparticle thin film manufacturing process and a nanoparticle thin film according to an embodiment of the present invention.
3 is a schematic diagram showing a ligand substitution process for a kind of a substituted solvent according to an embodiment of the present invention.
4 is a schematic diagram showing binding characteristics between a second ligand and a substituted solvent according to the type of the substitution solvent in the ligand substitution process according to an embodiment of the present invention.
5A to 5D are schematic diagrams showing charge transfer of a nanoparticle thin film according to an embodiment of the present invention.
6 is a scanning electron microscopy (SEM) image showing the surface of a nanoparticle thin film according to a type of a substitution solvent and a washing solvent according to an embodiment of the present invention.
7 is an AFM (atomic force microscopy) image showing the surface of a nanoparticle thin film according to the type of the substituted solvent according to an embodiment of the present invention.
8 is a SEM image showing the surface of a nanoparticle thin film according to the type of a substituted solvent when the second ligand according to an embodiment of the present invention is TBAC or TBAI.
9 is a SEM image showing the surface of the nanoparticle thin film according to the type of the substitution solvent and the ligand substitution time according to an embodiment of the present invention.
10A is a graph showing Fourier-transform infrared spectroscopy (FT-IR) according to the ligand substitution time in an embodiment of the present invention, and FIG. 10B is a normalized peak intensity according to the ligand substitution time for each type of substitution solvent in the embodiment of the present invention. It is a graph shown.
FIG. 11A is a graph showing an X-ray diffraction (XRD) pattern according to the type of a substitution solvent in an embodiment of the present invention, and FIG. 11B is a graph showing an XRD pattern according to the type of a washing solvent in an embodiment of the present invention.
12A is a graph showing the current-voltage curve of the nanoparticle thin film according to the type of the substituted solvent of the embodiment of the present invention, and FIG. 12B is the current-voltage curve of the nanoparticle thin film according to the type of the cleaning solvent of the embodiment of the present invention. It is a graph showing.
13A is a graph showing a change in resistance according to the type of a substituted solvent in an embodiment of the present invention, and FIG. 13B is a graph showing a change in resistance according to the type of a washing solvent in an embodiment of the present invention.
14A and 14B are graphs showing voltage versus current according to whether or not strain is applied for each type of substitution solvent in an embodiment of the present invention, and FIG. 14C is a graph showing a change in resistance according to the number of bendings for each type of substitution solvent in an embodiment of the present invention. It is a graph.
15A and 15B are graphs showing current versus voltage according to whether or not strain is applied for each type of washing solvent in an embodiment of the present invention, and FIG. 15C is a graph showing a change in resistance according to the number of bending for each type of washing solvent in an embodiment of the present invention. It is a graph.
16 is a graph showing a current-voltage curve for each strain of a nanoparticle thin film according to an embodiment of the present invention.
17 is a graph showing hysteresis according to whether or not strain is applied to a nanoparticle thin film according to an embodiment of the present invention.
18 is a graph showing a change in resistance according to a strain size of a nanoparticle thin film according to an embodiment of the present invention.
19 is a graph showing a change in resistance when strain-release of a nanoparticle thin film according to an embodiment of the present invention is repeated 1000 times.
20 is a graph showing a change in resistance according to a finger movement of a nanoparticle thin film according to an embodiment of the present invention.
21 is a graph showing a change in resistance according to a sound wave of a nanoparticle thin film according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and contents described in the accompanying drawings, but the present invention is not limited or limited by the embodiments.

The terms used in the present specification are for describing exemplary embodiments and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, “comprises” and/or “comprising” do not exclude the presence or addition of one or more other elements or steps to the mentioned elements or steps.

As used herein, "an embodiment", "example", "side", "example", etc. should be construed as having any aspect or design described better than or having an advantage over other aspects or designs. It is not.

In addition, the term'or' means an inclusive OR'inclusive or' rather than an exclusive OR'exclusive or'. That is, unless stated otherwise or unless clear from context, the expression'x uses a or b'means any one of natural inclusive permutations.

In addition, the singular expression ("a" or "an") used in this specification and claims generally means "one or more" unless otherwise stated or unless it is clear from the context that it relates to the singular form. Should be interpreted as.

The terms used in the description below have been selected as general and universal in the related technical field, but there may be other terms depending on the development and/or change of technology, customs, preferences of technicians, and the like. Therefore, terms used in the following description should not be understood as limiting the technical idea, but should be understood as illustrative terms for describing embodiments.

In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, detailed meanings of the terms will be described in the corresponding description. Therefore, terms used in the following description should be understood based on the meaning of the term and the contents throughout the specification, not just the name of the term.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

Meanwhile, in the description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms used in the present specification are terms used to properly express an embodiment of the present invention, which may vary depending on the intention of users or operators, or customs in the field to which the present invention belongs. Therefore, definitions of these terms should be made based on the contents throughout the present specification.

The present invention relates to a nanoparticle thin film with controlled mechanical and electrical properties and a method for manufacturing the same, wherein the mechanical and electrical properties of the nanoparticle thin film are improved by replacing the ligand surrounding the conductive nanoparticle and washing the substituted ligand. Can be adjusted.

In the description of the present invention, the mechanical properties refer to the gauge factor of the nanoparticle thin film of the present invention, and the gauge factor is a numerical value representing the sensitivity of the nanoparticle thin film of the present invention.

In the description of the present invention, the electrical properties refer to the resistivity of the nanoparticle thin film of the present invention, and the resistivity of the nanoparticle thin film of the present invention refers to the specific resistance of the nanoparticle thin film.

The resistance and the gauge factor will be dealt with in more detail in the description through the drawings to be described later.

Hereinafter, a method of manufacturing a nanoparticle thin film of the present invention will be described with examples and drawings.

1 is a flow chart showing a method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention.

Referring to FIG. 1, in the method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties according to an embodiment of the present invention, a first nanoparticle layer is formed by applying a solution containing conductive nanoparticles surrounded by a first ligand on a substrate. Forming a second nanoparticle layer in which the first ligand is substituted with the second ligand by supporting the substrate and the nanoparticle layer in a ligand substitution solution containing a second ligand and a substitution solvent (S120) ), preparing a nanoparticle thin film from which the second ligand has been removed by supporting the substrate and the second nanoparticle layer in a cleaning solvent (S130).

In the description of the present invention, the term "first nanoparticle layer" refers to a layer including conductive nanoparticles surrounded by a first ligand.

In addition, in the description of the present invention, the term "second nanoparticle layer" refers to a layer including conductive nanoparticles surrounded by a second ligand as a result of the first nanoparticle layer performing a ligand substitution process by the ligand substitution solution. .

In addition, in the description of the present invention, the term "nanoparticle thin film" refers to a final product manufactured by the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, and the second nanoparticle layer is washed with a washing solvent. It means the result of the process.

In this case, a detailed description of the ligand substitution process and the washing process will be described in detail in steps S120 and S130 to be described later.

In step S110, the substrate is a substrate that supports the first nanoparticle layer and is attached to an object to be measured that causes deformation by an external force.

Here, the object to be measured refers to an object for which pressure is to be sensed, and may be a solid object.

According to an embodiment, the object to be measured may be human skin, and the thin nanoparticles are attached to the skin to sense pressure, thereby recognizing blood pressure, pulse, voice, motion, and the like.

Alternatively, according to an embodiment, the object to be measured may be attached to an object that emits sound to detect movement of the object due to the impact of sound waves.

According to an embodiment, the substrate may include an adhesive layer on one surface to be attached to the object to be measured.

For example, the substrate may include an adhesive layer on a lower surface of the substrate to be attached to the object to be measured.

The substrate may be made of glass, quartz, Al ₂ O ₃ , SiC, Si, GaAs, or InP, but is not limited to the material.

The substrate may be made of a flexible material so as to be deformed by an external force such as a movement of the object to be measured.

Specifically, the substrate may be made of a flexible material such that pressure is sensed as the shape of the nanoparticle thin film is deformed when pressure is applied to the nanoparticle thin film, and the tunneling distance of the conductive nanoparticles included in the nanoparticle thin film is adjusted. have.

The principle of sensing the pressure while the shape of the nanoparticle thin film is deformed by an external force will be described with reference to FIGS. 5A to 5D to be described later.

According to an embodiment, the substrate may be made of an insulating material so that current does not pass through the body when the nanoparticle thin film is attached to the body.

For example, the substrate is polydimethylsiloxane (PDMS), polyimide (PI), polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI). ), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polycarbonate (PC), cellulose tree Although it may be selected from acetate (cellulose triacetate, CTA) and cellulose acetate propionate (CAP), it is not necessarily limited to the material as long as it has flexibility and insulation.

In step S110, the conductive nanoparticles are nanometer-sized spherical particles made of a conductive material.

For example, the conductive nanoparticles are at least among gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), nickel (Ni), tungsten (W), and iron (Fe). It may be a spherical particle including any one.

The first ligand is a ligand having a longer chain length than the second ligand, and may be an organic ligand made of an organic material.

According to an embodiment, the first ligand may include 8 to 18 carbon chains.

For example, the first ligand may include at least one of trioctylphosphineoxide (TOPO), octadecanol, oleic acid, and oleylamine.

The conductive nanoparticles may be synthesized and prepared in advance so as to be surrounded by the first ligand before step S110.

For example, when the conductive nanoparticles are silver nanoparticles, silver nitrate (AgNO ₃ ) may be mixed with oleic acid and oleylamine as first ligands to synthesize conductive nanoparticles surrounded by the first ligand.

The solution including the conductive nanoparticles surrounded by the first ligand may be a solution including a solvent for dispersing the conductive nanoparticles surrounded by the second ligand and the conductive nanoparticles surrounded by the first ligand.

The solvent for dispersing the conductive nanoparticles surrounded by the first ligand may be at least one of octane, hexane, and toluene according to an embodiment, and if it is a non-polar solvent, it is not limited to the material. .

According to an embodiment, the solution containing the conductive nanoparticles surrounded by the first ligand in step S110 is spin coating, spray coating, ultra-spray coating, electrospinning coating, Slot die coating, gravure coating, bar coating, roll coating, dip coating, shear coating, screen printing , Inkjet printing or nozzle printing may be applied on the substrate by any one method.

Alternatively, according to an embodiment, step S110 includes sputtering, atomic layer deposition (ALD), chemical vapor deposition (CVD), thermal evaporation, on the substrate, a solution containing conductive nanoparticles surrounded by a first ligand. ), co-evaporation, plasma enhanced chemical vapor deposition (PECVD), e-beam evaporation, RF sputtering, magnetron sputtering, vacuum deposition Alternatively, the first nanoparticle layer may be formed by depositing by any one of chemical vapor deposition.

According to an embodiment, in step S110, the first nanoparticle layer may be formed by applying a solution containing conductive nanoparticles surrounded by the first ligand on the substrate and then performing an additional drying process.

In step S120, a ligand substitution process is performed in which the substrate and the first nanoparticle layer are supported in the ligand substitution solution to replace the first ligand with the second ligand.

The ligand substitution solution is a solution containing a second ligand and a substitution solvent for dispersing the second ligand.

The second ligand may be a ligand having a shorter chain length than the first ligand.

Depending on the embodiment, the second ligand may be an organic ligand including 1 to 3 carbon chains or an inorganic ligand including an inorganic material.

For example, the second ligand may be an organic ligand including at least one of 3-mercaptopropionic acid (MPA), 1,2-ethanedithiol (EDT), and ethylenediamine (EDA), but is not limited to the material. .

Or, for example, the second ligand is a sulfur ions (S ^2-), chloride ion (Cl ^-), bromide ion (Br ^-), thiocyanate ion (SCN ^-), iodine ion (I ^-), disulfide cargo ion (HS ^-), tellurium ions (Te ^2-), hydroxide ions (OH ^-), boric tetrafluoride ion (BF ₄ ^-) and six hexafluorophosphate ion (PF ₆ ^-) arms comprises at least one of It may be a ligand, but is not limited to the substance.

The substitution solvent is a solvent for dispersing the second ligand, and is a factor that determines a substitution rate when the first ligand surrounding the conductive nanoparticles is substituted with a second ligand.

In the substitutional solvent, the rate at which the first ligand is substituted with the second ligand varies depending on the polarity level.If the substitution solvent is highly polar, the rate at which the first ligand is substituted with the second ligand is slow, so the nanoparticle thin film Cracks and defects occur on the surface of the.

Accordingly, the nanoparticle thin film may have high resistance and high deformability including a number of cracks and defects on the surface, and thus may have a high gauge factor.

When the polarity of the substitution solvent is low, the first ligand is substituted with the second ligand at a high rate, so that the surface of the nanoparticle thin film may have fewer cracks and defects.

Accordingly, the nanoparticle thin film may have low resistance and low deformability, including few cracks and defects on the surface, and thus may have a low gauge factor.

That is, the resistance of the nanoparticle thin film by controlling the degree of formation of cracks and defects on the surface of the nanoparticle thin film according to the type of the substitution solvent used in the process of substituting the first ligand with the second ligand when preparing the nanoparticle thin film. Degrees and gauge factors can be adjusted.

Therefore, in the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, a nanoparticle having a resistance and a gauge factor desired by an operator (means a subject that manufactures the nanoparticle thin film) simply selects the type of the substituted solvent. A thin film can be easily manufactured.

In this case, the principle of controlling the resistance and gauge factor of the nanoparticle thin film according to the type of the substituted solvent will be described with reference to FIGS. 3 and 4 to be described later.

According to an embodiment, the substitution solvent may be at least one of methanol, ethanol, and iso-propanol.

As the ligand substitution process occurs by the ligand substitution solution in step S120, the second nanoparticle layer may include conductive nanoparticles in which the first ligand is substituted with the second ligand.

Step S130 may wash the second nanoparticle layer by supporting the substrate and the second nanoparticle layer in a cleaning solvent.

In this case, washing the second nanoparticle layer in step S130 means removing some of the second ligands included in the second nanoparticle layer.

Specifically, the second nanoparticle layer includes conductive nanoparticles substituted with the second ligand, and may have a shape in which the second ligand is partially bonded to the surface of the conductive nanoparticle.

Step S130 may remove a part of the second ligand bound to the surface of the conductive nanoparticles by supporting the conductive nanoparticles partially bound to the second ligand of the second nanoparticle layer in the washing solvent.

Accordingly, the nanoparticle thin film may include a substrate and a second nanoparticle layer from which the second ligand is partially removed.

The cleaning solvent is a solvent that removes a part of the second ligand included in the second nanoparticle layer, and the composition of the second ligand bound to the surface of the conductive nanoparticle may vary depending on the cleaning solvent.

The amount of the second ligand dropped from the surface of the conductive nanoparticles may vary according to the polarity of the washing solvent.

That is, while the composition of the second ligand on the surface of the conductive nanoparticles is changed by the washing solvent, the resistance degree and the gauge factor of the nanoparticle thin film may be changed.

For example, when the cleaning solvent has a high polarity, the second ligand on the surface of the conductive nanoparticles is well dropped, so that the composition of the second ligand on the surface of the conductive nanoparticles decreases.

Accordingly, the nanoparticle thin film may have a low gauge factor while having a low resistance due to a low second ligand composition on the surface of the conductive nanoparticle.

When the polarity of the cleaning solvent is low, the second ligand on the surface of the conductive nanoparticles cannot be easily dropped, and the composition of the second ligand on the surface of the conductive nanoparticles is high.

Accordingly, the nanoparticle thin film may have a high gauge factor while having high resistance due to the high second ligand composition on the surface of the conductive nanoparticle.

That is, when preparing the nanoparticle thin film, the composition of the second ligand on the surface of the nanoparticle thin film varies according to the type of the cleaning solvent that separates the second ligand from the surface of the conductive nanoparticle, so that the resistance and the gauge factor of the nanoparticle thin film can be adjusted have.

Accordingly, the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention can easily manufacture a nanoparticle thin film having a resistance degree and a gauge factor desired by an operator by simply selecting the type of the cleaning solvent.

In this case, the principle of controlling the resistance and gauge factor of the nanoparticle thin film according to the type of the cleaning solvent will be described with reference to FIGS. 5A to 5D to be described later.

According to an embodiment, the washing solvent may be at least one of methanol, ethanol, and iso-propanol.

Unlike conventional techniques using a lithography system and high vacuum conditions, the nanoparticle thin film according to the embodiment of the present invention can be easily manufactured at room temperature by a solution process, and by simply selecting the type of the replacement solvent and the washing solvent, the operator It is possible to prepare a nanoparticle thin film having a desired resistance and a gauge factor.

In the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, a nanoparticle thin film having a desired resistance and a gauge factor can be manufactured by an operator by selecting the type of the substitution solvent and the washing solvent.

In this case, the substitution solvent and the washing solvent may be the same or different materials.

Depending on the embodiment, both the substitution solvent and the washing solvent may be methanol, and both the substitution solvent and the washing solvent may be isopropanol.

Example Accordingly, when the substitution solvent is methanol and the washing solvent is isopropanol, the prepared nanoparticle thin film may have a high resistance and a high gauge factor.

That is, when the replacement solvent is methanol and the washing solvent is isopropanol, there are many cracks on the surface of the prepared nanoparticle thin film, and the second ligand composition on the surface of the conductive nanoparticles is high due to the washing solvent of low polarity, and thus, high resistance and It has a high gauge factor, and the nanoparticle thin film can be used as an active layer.

According to an embodiment, when the substitution solvent is isopropanol and the washing solvent is methanol, the prepared nanoparticle thin film may have a low resistance and a low gauge factor.

That is, when the substituted solvent is isopropanol and the washing solvent is methanol, the resistance of the prepared nanoparticle thin film is low and the resistance change is small, and thus the nanoparticle thin film can be used as an electrode.

Accordingly, the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention can control the electrical properties of the nanoparticle thin film by preparing a nanoparticle thin film having a low or high resistivity according to the type of the substituted solvent.

2 is a schematic diagram showing an enlarged view of a nanoparticle thin film manufacturing process and a nanoparticle thin film according to an embodiment of the present invention.

Referring to FIG. 2, first, a part of the upper surface of the PET substrate 110 is covered with a Kapton tape 111, and then a solution containing silver nanoparticles surrounded by a first ligand is covered with a Kapton tape 111. The first nanoparticle layer 120 was formed by coating on 110) by a spin coating method.

Thereafter, the substrate 110 on which the first nanoparticle layer is formed is immersed in a ligand substitution solution containing isopropanol as a substitution solvent and TBAB (tetra n-butylammonium bromide) as a second ligand, and the first ligand is substituted with the second ligand, 2 To form a nanoparticle layer (not shown).

Thereafter, the substrate 110 on which the second nanoparticle layer is formed may be washed with methanol, which is a washing solvent, for 2 minutes to prepare a nanoparticle thin film 100 having low resistance and low sensitivity.

According to the embodiment, after removing the Kapton tape 111 of the nanoparticle thin film 100, a ligand substitution process and a washing process may be performed once more.

By removing the Kapton tape 111 of the nanoparticle thin film 100, the nanoparticle thin film includes the first region 101 in which the second nanoparticle layer from which the second ligand is removed is formed, and the Kapton tape 111 is removed, and the substrate ( 110) may be divided into the exposed second area 102.

Specifically, after removing the Kapton tape 111 of the nanoparticle thin film 100, a solution containing silver nanoparticles surrounded by the first ligand was spin-coated on the first region 101 and the second region 102 again. The first nanoparticle layer 220 is formed.

Thereafter, by supporting the substrate 110 on which the first nanoparticle layer 220 is formed in a ligand substitution solution containing methanol as a substitution solvent and TBAB as a second ligand, the first ligand is substituted with the second ligand, and the second nanoparticle layer ( Not shown) can be formed.

Thereafter, the substrate 110 on which the second nanoparticle layer is formed may be supported in isopropanol, which is a cleaning solvent, for 10 seconds to prepare a nanoparticle thin film 200 from which the second ligand has been removed.

According to an embodiment, the sensitivity of the nanoparticle thin film may be further improved by applying a pre-strain to the nanoparticle thin film 200 to further form a crack on the surface of the nanoparticle thin film 200.

Accordingly, the nanoparticle thin film includes a first region 101 prepared using isopropanol as a substitution solvent and methanol as a washing solvent, and a second region 102 prepared using methanol as a substitution solvent and isopropanol as a washing solvent. Can include.

Referring to the enlarged image shown in FIG. 2, the first region 101 uses methanol having a high polarity as a washing solvent to remove a lot of the second ligand on the surface of the silver nanoparticles, and the second region 102 has a polarity. With the use of low isopropanol, less of the second ligand on the surface of the silver nanoparticles can be removed.

Therefore, in the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, the nanoparticle thin film is divided into a first region 101 and a second region 102 using the Kapton tape 111, and the first region 101 ) And the second region 102 may each have different resistances and gauge factors, so that the nanoparticle thin film 200 may be manufactured.

For example, the first region 101 prepared using isopropanol as a substitution solvent and methanol as a washing solvent may be used as an electrode, and the second region 101 prepared using methanol as a substitution solvent and isopropanol as the washing solvent ( 102) may be used as an active layer, and may include a configuration that serves as an electrode and an active layer in one nanoparticle thin film.

In the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, a resistance degree and a gauge factor of the nanoparticle thin film may be adjusted according to a time for substituting the first ligand with the second ligand, as well as the type of the substitution solvent.

In this case, the time for substituting the first ligand with the second ligand means a time for supporting the substrate and the first nanoparticle layer in the ligand substitution solution.

The first ligand has non-conductive properties and the second ligand has conductivity. As the ligand substitution time increases, the amount of substitution of the first ligand with the second ligand increases, thereby increasing the conductivity of the nanoparticle thin film. .

Depending on the embodiment, the time for substituting the first ligand with the second ligand may be 10 seconds to 120 seconds.

If the time for substituting the first ligand with the second ligand is less than 10 seconds, there is a problem in that the conductivity of the nanoparticle thin film is remarkably low because the time for substituting the first ligand with the second ligand is insufficient.

If the time for substituting the first ligand with the second ligand is 120 seconds, since the first ligand is all substituted with the second ligand, substituting the ligand for more than 120 seconds will result in a change in the resistance of the nanoparticle thin film. There is no meaningless.

Accordingly, the resistance of the nanoparticle thin film may be adjusted to 6.37x10 ^{-6 Ωcm to 3.1Ωcm.}

The gauge factor may be calculated through a change in the resistance of the nanoparticle thin film.

The gauge factor refers to the sensitivity of the nanoparticle thin film, and can be calculated by the following equation.

[Equation]

G=(△R/R ₀ )/ε

Here, G is the gauge factor of the nanoparticle thin film, ΔR is the amount of resistance change of the nanoparticle thin film, R ₀ is the initial resistance of the nanoparticle thin film, and ε is the strain applied to the nanoparticle thin film.

That is, the gauge factor can be said to be a numerical value indicating how well the nanoparticle thin film detects strain change. Therefore, it means that the larger the gauge factor value, the more sensitive the nanoparticle thin film detects the strain change.

Accordingly, the gauge factor of the nanoparticle thin film may be adjusted to 3.1 to 400.

In addition, the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention can control the electrical and mechanical properties of the nanoparticle thin film by preparing a nanoparticle thin film having a low or high resistance and a gauge factor according to the type of cleaning solvent. .

Specifically, in the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, the resistance and the gauge factor of the nanoparticle thin film may be adjusted according to not only the type of the cleaning solvent but also the time for removing the second ligand.

In this case, the time for removing the second ligand means a time for immersing the substrate and the second nanoparticle layer in a cleaning solvent.

The washing solvent not only serves to remove impurities such as the first ligand remaining after ligand substitution and the second ligand remaining unsubstituted, but also removes salts formed on the surface of the conductive nanoparticles to improve the conductivity of the nanoparticle thin film. You can increase it.

Accordingly, as the time for removing the second ligand increases, the amount of salt formed on the surface of the conductive nanoparticles increases, so that the resistance of the nanoparticle thin film decreases.

Depending on the embodiment, the time to remove the second ligand may be 10 seconds to 120 seconds.

If the time to remove the second ligand is less than 10 seconds, the salt formed on the surface of the conductive nanoparticles cannot be sufficiently removed because it is not sufficiently washed, and if it exceeds 120 seconds, the salt or impurities are sufficiently removed and the nanoparticle thin film is no longer the nanoparticle thin film. It is meaningless because the resistance of the person does not change.

Accordingly, the resistance of the nanoparticle thin film ^{may be adjusted to 6.37x10 -6} Ωcm to 3.1Ωcm, and the gauge factor of the nanoparticle thin film may be adjusted to 3.1 to 400.

Accordingly, the nanoparticle thin film according to the embodiment of the present invention is controlled by controlling not only the type of solvent and washing solvent for replacing the nanoparticle thin film, but also the time for substituting the first ligand with the second ligand and the time for removing the second ligand. The resistance and gauge factor can be adjusted.

Hereinafter, the principle of ligand substitution according to the type of the substitution solvent of the nanoparticle thin film will be described with reference to FIG. 3.

3 is a schematic diagram showing a ligand substitution process for a kind of a substituted solvent according to an embodiment of the present invention.

3 is a schematic diagram showing a ligand substitution process when silver nanoparticles surrounded by the first ligand 122 are supported in a ligand substitution solution containing TBAB as a substitution solvent.

Referring to FIG. 3, when the first nanoparticle layer 120 including the conductive nanoparticles 121 surrounded by the substrate 110 and the first ligand 122 is supported in the ligand substitution solution, the first ligand 122 The rate of substitution with bromine ion (Br ⁻ ) as the second ligand may be faster in the case of isopropanol than in the case of methanol as the substitution solvent.

When the substitution solvent is isopropanol, the ligand substitution speed is high, so that the silver nanoparticles adjacent to each other are rapidly attached to each other, thereby forming a second nanoparticle layer (not shown) with almost no cracks.

On the other hand, when the substitution solvent is methanol, the ligand substitution rate is slow, so that the silver nanoparticles adjacent to each other are not easily adhered by the first ligand 122, so that an empty space is formed between the conductive nanoparticles, and the second nanoparticles with many cracks on the surface. A particle layer can be formed.

Accordingly, since the ligand substitution rate is changed according to the polarity of the substitution solvent, the degree of crack formed on the surface of the finally prepared nanoparticle thin film can be varied.

Hereinafter, a principle in which the ligand substitution rate varies depending on the type of the substitution solvent will be described with reference to FIG. 4.

4 is a schematic diagram showing binding characteristics between a second ligand and a substituted solvent according to the type of the substitution solvent in the ligand substitution process according to an embodiment of the present invention.

^{FIG. 4 shows the binding characteristics of bromine ions (Br −} ), which are the second ligands 123, and the substitution solvent in the embodiment when silver nanoparticles are used as conductive nanoparticles and TBAB is used as the second ligand 123. .

In addition, the thickness of the red line shown in FIG. 4 means the bonding strength between particles.

Referring to FIG. 4, the ligand substitution rate may be determined by the polarity of the substitution solvent and the number of carbon chains in the substitution solvent.

When TBAB is dissolved in the substitution solvent, the bromine ion is surrounded by the positive charge of the substitution solvent and binds to the substitution solvent molecule.

Accordingly, when methanol having a high polarity of 0.762 is used as a substitution solvent, the first ligand 122 surrounding the silver nanoparticles is the bromine ion, which is the second ligand 123, because the number of carbons is small and has a strong binding force with the bromine ion. As it is not well substituted with, the ligand substitution rate is low.

However, in the case of using isopropanol having a low polarity of 0.546 as the substitution solvent, the first ligand 122 surrounding the silver nanoparticles is bromine, which is the second ligand 123, because the number of carbons is greater than that of methanol and has weak binding strength with bromine ions. Since it is well substituted with ions, the ligand substitution rate may be high.

When the substitution solvent is ethanol, the polarity is 0.675, which is smaller than methanol and has a greater polarity than isopropanol, so the ligand substitution rate at which the first ligand 122 is substituted with the second ligand 123 is lower than that of methanol and is less than that of isopropanol. It can be big.

Therefore, in the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, the ligand substitution rate is different depending on the type of the substitution solvent, and the degree of crack formed on the surface of the nanoparticle thin film is adjusted to prepare a nanoparticle thin film with controlled resistance. can do.

According to the manufacturing method of the nanoparticle thin film according to the embodiment of the present invention, the crack formed on the surface of the nanoparticle thin film and the composition of the second ligand are adjusted according to the type of the substitution solvent and the washing solvent, and the resistance and the gauge factor are adjusted. Nanoparticle thin films can be prepared.

In the nanoparticle thin film, the number of charge transfer paths is adjusted according to cracks on the surface of the second nanoparticle layer and the composition of the second ligand on the surface of the conductive nanoparticles, so that the resistance and the gauge factor of the nanoparticle thin film may vary.

Hereinafter, the charge transfer characteristics according to the type of the replacement solvent and the washing solvent of the nanoparticle thin film will be described with reference to FIGS. 5A to 5D.

5A to 5D are schematic diagrams showing charge transfer of a nanoparticle thin film according to an embodiment of the present invention.

At this time, the red arrows shown in FIGS. 5A to 5D indicate the direction of movement of electric charges.

First, referring to FIG. 5A, when the substitution solvent is methanol, the ligand substitution speed of the conductive nanoparticles is slow, so that cracks may be formed on the surface of the nanoparticle thin film 100.

Therefore, as the red arrow shown in FIG. 5A, the charge transfer path is not completely formed, so that the charge can be transferred without a certain direction.

Accordingly, the nanoparticle thin film 100 may have high resistance.

When the nanoparticle thin film 100 is bent when the substitution solvent is methanol, the charge transfer path formed incompletely near the crack is easily cut off due to the stress concentration phenomenon.

Accordingly, when the nanoparticle thin film 100 is bent when the substitutional solvent is methanol, the number of charge transfer paths decreases compared to before bending, so that pressure can be sensitively sensed, and thus a relatively high gauge factor can be obtained.

Referring to FIG. 5B, when the substitution solvent is isopropanol, the ligand substitution speed of the conductive nanoparticles is high, so that the conductive nanoparticles are attached to each other, so that almost no cracks may be formed on the surface of the nanoparticle thin film 100.

Accordingly, the nanoparticle thin film 100 may have a low resistance as a charge transfer path is well formed as shown by the red arrow shown in FIG. 5B, and charges are transferred while having a certain direction.

When the substitutional solvent is isopropanol, the nanoparticle thin film 100 has a high ligand substitution rate, so conductive nanoparticles adjacent to each other are attached to each other, so even if the nanoparticle thin film 100 is bent, the charge transfer path may be hardly affected.

Therefore, when the replacement solvent is isopropanol, since it does not affect the charge transfer path regardless of before and after bending the nanoparticle thin film 100, pressure is not sensitively sensed, and a gauge factor that is relatively lower than when the replacement solvent is methanol is obtained. I can have it.

Referring to FIG. 5C, when the washing solvent is methanol, a small amount of the second ligand 123 is bonded to the surface of the conductive nanoparticles 121, so that the conductivity is excellent and the insulation property is low.

Therefore, when the washing solvent is methanol, the nanoparticle thin film may have a low resistance.

In addition, when the washing solvent is methanol, the nanoparticle thin film includes the conductive nanoparticle 121 to which a small amount of the second ligand 123 is bonded, and the charge transfer path is hardly affected when the nanoparticle thin film is bent, so the pressure is sensitive. It may not be detected properly and may have a low gauge factor.

Accordingly, when the substitution solvent is isopropanol and the washing solvent is methanol, the nanoparticle thin film prepared by the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention has a high ligand substitution rate, so that almost no cracks are generated on the surface. As the conductive nanoparticles 121 are densely formed with each other, a charge transfer path is well generated, so that the conductive nanoparticles 121 are excellent in conductivity and can be used as electrodes.

Since the substitutional solvent isopropanol has a faster ligand substitution rate than methanol, the fact that the conductive nanoparticles 121 are densely clustered with each other means the distance between the conductive nanoparticles 121 in the case of isopropanol than in the case of methanol as the substitutional solvent. It can be understood that is relatively narrowed.

When the substituted solvent is isopropanol having a low polarity, the nanoparticle thin film ^{has a low resistance of 6.37x10 -6} Ωcm to 8.03x10 ^-6 Ωcm, so that the nanoparticle thin film can be used as an electrode.

Referring to FIG. 5D, when the cleaning solvent is isopropanol, a large amount of the second ligand 123 is bonded to the surface of the conductive nanoparticles 121 and the distance between the conductive nanoparticles 121 is increased by L, so that charge transport may occur. .

At this time, when the nanoparticle thin film is bent, the distance between the conductive nanoparticles 121 increases from L to L+α, making charge tunneling difficult, and thus the nanoparticle thin film can have high resistance.

In addition, when the cleaning solvent is isopropanol, when the nanoparticle thin film is bent while the distance between the conductive nanoparticles 121 is L by a large amount of the second ligand 123, the distance between the conductive nanoparticles 121 increases to L+α. Therefore, the nanoparticle thin film can easily detect pressure and have a high gauge factor.

Accordingly, when the substitution solvent is methanol and the washing solvent is isopropanol, the nanoparticle thin film prepared by the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention has a slow ligand substitution rate, so that the conductive nanoparticles 121 are dense with each other. Since it is not densely concentrated, cracks are formed on the surface, and charge tunneling becomes difficult due to a large amount of second ligands on the surface of the conductive nanoparticles, so that it can be used as an active layer.

Since the substitutional solvent isopropanol has a faster ligand substitution rate than methanol, the fact that the conductive nanoparticles 121 are not densely clustered with each other means that the conductive nanoparticles 121 in the case of methanol than in the case where the substitutional solvent is isopropanol. ), it can be understood that the distance between them is relatively long.

When the substitution solvent is methanol having a high polarity, the nanoparticle thin film has a high resistivity of 0.7Ωcm to 3.1Ωcm, so that the nanoparticle thin film may be used as an active layer.

Accordingly, in the method of manufacturing a nanoparticle thin film according to an embodiment of the present invention, the electrical properties of the nanoparticle thin film can be adjusted according to the type of the substitution solvent and the washing solvent, and a gauge factor, which is a mechanical property.

Hereinafter, a nanoparticle thin film was prepared according to an example of the method for producing a nanoparticle thin film of the present invention, and properties and effects of the nanoparticle thin film were evaluated.

Hereinafter, in the examples and characteristic evaluation, when the exchange solvent is A and the rinsing solvent is B, the prepared nanoparticle thin film is expressed _{as E A} R _B.

reagent

Silver nitrate (99%, AgNO ₃ ) powder and TBAI (98%, tetra n-butylammonium iodide) were purchased from Alfa Aesar Co., Inc.

Oleic acid (90%), oleylamine (70%), TBAC (97%, tetra n-butylammonium chloride), TBAB (99.0%), 3-mercaptopropyl trimethoxysilane (95%, (3-mercaptopropyl) )methoxysilane), methanol (99.8%), ethanol (99.5%) and isopropanol (99.5%) were purchased from Sigma-Aldrich.

A PET film having a thickness of 250 μm was purchased from SKC Film, and was used as a flexible substrate.

Example

[Example 1-1]

1.Synthesis of silver nanoparticles

1.7 g of silver nitrate, 45 mL of oleic acid, and 5 mL of oleylamine were added to a three-necked flask, and a mixed solution was prepared using magnetic stirring.

In order to remove moisture and oxygen in the mixed solution, the mixed solution was degassed at 70° C. for 1 hour and 30 minutes.

After degassing, the temperature of the three-necked flask was raised to 180°C at a rate of 1°C/min, and then cooled to room temperature to synthesize silver nanoparticles (Ag NC).

The synthesized silver nanoparticles were washed 5 times by centrifuging for 5 minutes at 5000 rpm using toluene and ethanol.

The precipitated silver nanoparticles were dispersed in octane at a concentration of 200mg/mL to prepare a solution containing silver nanoparticles surrounded by the first ligand.

2. Preparation of Ligand Substitution Solution

The ligand exchange solution was prepared by preparing TBAB as a second ligand in methanol as a washing solvent at a concentration of 30 mM.

3. Nanoparticle thin film fabrication

PET substrates (thickness 250 μm) were sequentially sonicated in acetone, isopropanol, and deionized water for 5 minutes each.

Then, it was treated with UV ozone so that a hydroxyl group (-OH) could be formed on the surface of the PET substrate.

Thereafter, the PET substrate was supported in a solution of 3-mercaptopropyl trimethoxysilane added to toluene in an amount of 5% by volume to form a self-assembled monolayer.

Thereafter, the silver nanoparticles prepared on the PET substrate were spin-coated at a speed of 1000 rpm to form a first nanoparticle layer.

Thereafter, the PET substrate on which the first nanoparticle layer was formed was supported on the ligand-substituted solution to form a second nanoparticle layer in which the ligand was substituted.

Thereafter, the PET substrate on which the second nanoparticle layer was formed was supported in methanol, which is a washing solvent, to prepare a nanoparticle thin film (E _M R _M ) from which the second ligand was partially removed.

[Example 1-2]

Except that the substitution solvent was ethanol, a nanoparticle thin film (E _E R _M ) was prepared in the same manner as in [Example 1-1].

[Example 1-3]

_{A nanoparticle thin film (E I} R _M ) was prepared in the same manner as in [Example 1-1], except that the substitution solvent was isopropanol.

[Example 2-1]

Except that the washing solvent was ethanol, a nanoparticle thin film (E _M R _E ) was prepared in the same manner as in [Example 1-1].

[Example 2-2]

Except that the substitution solvent was ethanol, a nanoparticle thin film (E _E R _E ) was prepared in the same manner as in [Example 2-1].

[Example 2-3]

_{A nanoparticle thin film (E I} R _E ) was prepared in the same manner as in [Example 2-1], except that the substitution solvent was isopropanol.

[Example 3-1]

_{A nanoparticle thin film (E M} R _I ) was prepared in the same manner as in [Example 1-1], except that the washing solvent was isopropanol.

[Example 3-2]

Except that the substitution solvent was ethanol, a nanoparticle thin film (E _E R _I ) was prepared in the same manner as in [Example 3-1].

[Example 3-3]

_{A nanoparticle thin film (E I} R _I ) was prepared in the same manner as in [Example 3-1], except that the substitution solvent was isopropanol.

[Example 4-1]

_{A nanoparticle thin film (E M} R _M ) was prepared in the same manner as in [Example 1-1], except that TBAC was used as the first ligand.

[Example 4-2]

_{A nanoparticle thin film (E I} R _M ) was prepared in the same manner as in [Example 4-1], except that isopropanol was used as the substitution solvent.

[Example 5-1]

_{A nanoparticle thin film (E M} R _M ) was prepared in the same manner as in [Example 1-1], except that TBAI was used as the first ligand.

[Example 5-2]

_{A nanoparticle thin film (E I} R _M ) was prepared in the same manner as in [Example 5-1], except that isopropanol was used as the substitution solvent.

[Control example]

_{A nanoparticle thin film (E M} R _X ) was prepared in the same manner as in [Example 1-1], except that the PET substrate on which the second nanoparticle layer was formed was not washed.

The examples 1-1 to 5-2 and the control examples are summarized in Table 1 below according to the type of substitution solvent and washing solvent.

[Table 1]

Property evaluation

1. Observation of the surface of the nanoparticle thin film

6 is a scanning electron microscopy (SEM) image showing the surface of a nanoparticle thin film according to a type of a substitution solvent and a washing solvent according to an embodiment of the present invention.

It can be seen that Examples 1-1 to 3-3 have different uniformity and roughness depending on the type of the replacement solvent and the washing solvent.

First, looking at the surface characteristics according to the type of the substitution solvent of the above embodiments are as follows.

Referring to FIG. 6A, in the case of Example 1-1, it can be seen that there are 3 to 4 large holes per ^{100 μm 2 on average, and there are many pin holes on the surface.}

At this time, the size of the large hole exceeded 2 μm, and the pin hole was a hole having a size smaller than 500 nm.

Referring to FIG. 6B, in the case of Example 1-2, a large hole was not observed, and it can be seen that the size of the pin hole is about 100 nm to 200 nm.

Referring to FIG. 6C, in the case of Example 1-3, it can be seen that neither the large hole nor the pin hole is observed.

The surface characteristics of the above embodiments according to the type of cleaning solvent are as follows.

Referring to Figure 6 (a), (d), and (g), in the case of Example 1-1, Example 2-1, and Example 3-1, it can be seen that no significant difference was observed on the surface. have.

Referring to (b), (e), and (h) of FIG. 6, it can be seen that no significant difference on the surface was observed even in Examples 1-2, 2-2, and 3-2. have.

Referring to (c), (f), and (i) of FIG. 6, it can be seen that no significant difference on the surface was observed even in Examples 1-3, 2-3, and 3-3. have.

Accordingly, it can be seen that structural properties such as cracks formed on the surface of the nanoparticle thin film of the present invention were affected by the type of the substitution solvent, but the type of the washing solvent had little influence.

Hereinafter, the surface roughness of Examples 1-1 to 1-3 according to the type of the substituted solvent is as follows.

7 is an AFM (atomic force microscopy) image showing the surface of a nanoparticle thin film according to the type of a substituted solvent according to an embodiment of the present invention.

Referring to FIG. 7A, similar to the surface characteristics of FIG. 6, in the case of Example 1-1, it can be seen that many holes were formed on the surface.

Referring to FIG. 7B, in the case of Example 1-2, it can be seen that fewer holes were formed than in Example 1-1.

Referring to Figure 7 (c), in the case of Example 1-3, it can be seen that a lot of precipitates were formed by adhesion between the silver nanoparticles, so that it has a rougher surface than that of Examples 1-1 and 1-2. have.

The square root roughness values (R _q ) of Examples 1-1 to 1-3 are 98±12 nm, 118±14 nm, and 108±11 nm, respectively, and the lower the polarity of the substitution solvent, the more cracks on the surface of the nanoparticle thin film. It can be seen that the surface roughness value increases due to the adhesion between the conductive nanoparticles without formation.

Hereinafter, the surface characteristics of the nanoparticle thin film according to the type of the first ligand are as follows.

8 is a SEM image showing the surface of a nanoparticle thin film according to the type of a substituted solvent when the second ligand according to an embodiment of the present invention is TBAC or TBAI.

Referring to FIG. 8A, it can be seen that in the case of Example 4-1, a plurality of holes and pinholes were formed on the surface of the nanoparticle thin film as in the case of Example 1-1.

Referring to FIG. 8B, it can be seen that in the case of Example 4-2, as in the case of Example 1-3, large holes were hardly formed on the surface of the nanoparticle thin film.

Referring to FIG. 8C, it can be seen that in the case of Example 5-1, as in the case of Example 1-1, a plurality of holes and pinholes were formed on the surface of the nanoparticle thin film.

Referring to FIG. 8D, it can be seen that in the case of Example 5-2, as in the case of Example 1-3, almost no large pores were formed on the surface of the nanoparticle thin film.

Therefore, even when the second ligand is TBAC or TBAI, as in the case where the second ligand is TBAB, the lower the polarity of the substitution solvent, the faster the ligand substitution rate, so that cracks are not formed on the surface of the nanoparticle thin film.

9 is a SEM image showing the surface of the nanoparticle thin film according to the type of the substitution solvent and the ligand substitution time according to an embodiment of the present invention.

In this case, the ligand substitution time refers to a time from the time when the substrate on which the first nanoparticle layer is formed is started to be supported in the ligand substitution solution to the time when the supported substrate is removed from the ligand substitution solution.

9, in the case of Example 1-1 (MeOH) and Example 1-3 (IPA), as the ligand substitution time increased, the first ligand was continuously substituted with the second ligand, so that the surface of the nanoparticle thin film It can be seen that a hole is formed in the.

In addition, for the same ligand substitution time, since Example 1-1 uses a substitution solvent having a higher polarity than Example 1-3, the substitution rate is relatively faster than that of Example 1-3. It can be seen that a hole is formed.

Therefore, it can be confirmed that the size and number of cracks on the surface of the nanoparticle thin film can be adjusted according to the ligand substitution time, and the size and number of cracks on the surface of the nanoparticle thin film can be adjusted for the same ligand substitution time according to the polarity of the substitution solvent. have.

Hereinafter, FT-IR and XRD of the nanoparticle thin film according to the ligand substitution rate, the substitution solvent, and the type of washing solvent of the above examples are as follows.

2. FT-IR and XRD analysis

10A is a graph showing Fourier-transform infrared spectroscopy (FT-IR) according to ligand substitution time in an embodiment of the present invention.

Referring to Figure 10a, the Ag NC synthesized for Example 1-1 is surrounded by an oleate ligand, the ligand substitution time is 0 seconds (M 0s), 2 seconds (M 2s), 5 seconds (M 5s) , It can be seen that a strong CH stretching vibration band peak of ^{about 2800-3000cm -1} is observed at 10 seconds (M 10s).

It can be seen that as the ligand substitution time increases, the peak gradually disappears according to the ligand exchange time, which means that the oleate ligand, which is the first ligand bound to the surface of the silver nanoparticle, becomes the inorganic ligand (the second ligand) of the ^Br-ion. It indicates that it is gradually replaced.

In the case of Example 1-1, in which methanol is used as a substitution solvent, it can be seen that almost all of the first ligand is substituted with the second ligand after 20 seconds of the ligand substitution time.

10B is a graph showing the normalized peak intensity according to the ligand substitution time for each type of substitution solvent according to an exemplary embodiment of the present invention.

Figure 10b shows the normalized peak intensity for the C-H stretching vibration band according to the type of the substitution solvent. At this time, the'time' of the x-axis of FIG. 10B means the ligand substitution time.

Referring to FIG. 10B, in the case of Examples 1-1 to 1-3, the normalization peak intensity decreases as the ligand exchange time (x-axis in FIG. 10B) increases, so that the first ligand is substituted with the second ligand. It can be seen that when the ligand substitution time is about 60 seconds, the normalized peak intensity is hardly observed.

However, in the case of Example 1-1 with respect to the same ligand substitution time in Examples 1-1 to 1-3, it was found that the peak intensity was strong, so that the ligand substitution rate of Example 1-1 was the slowest. I can.

In addition, it can be seen that the peak intensity is strong for the same ligand substitution time in the order of Example 1-2 and Example 1-3, and accordingly, the ligand substitution rate in the order of Example 1-2 and Example 1-3. You can see that is slow.

Accordingly, it can be seen that the stronger the polarity of the substitution solvent used in the method for producing a nanoparticle thin film of the present invention, the slower the ligand substitution rate.

FIG. 11A is a graph showing an X-ray diffraction (XRD) pattern according to the type of a substitution solvent in an embodiment of the present invention, and FIG. 11B is a graph showing an XRD pattern according to the type of a washing solvent in an embodiment of the present invention.

First, referring to FIG. 11A, it can be seen that all of Examples 1-1 to 1-3 exhibit peaks at 31.0° by the AgBr (200) crystal plane and 38.3° by the Ag (111) crystal plane. .

This shows that the bromine ion, which is a second ligand, is attached to the surface of the silver nanoparticles during the ligand exchange process to form AgBr.

11B, the control example (E _M R _X ), the example 3-1 (E _M R _I ), the example 2-1 (E _M R _E ), the example 1-1 (E _It can be seen that the peak corresponding to AgBr is large in the order of M R _{M ).}

The size of the AgBr peak indicates the relative amount of AgBr present in Example 1-1, Example 2-1, Example 3-1, and the control example. It can be seen that the solvent plays a role in removing AgBr.

In addition, in Example 1-1 where the washing solvent is methanol, Example 2-1 in which the washing solvent is ethanol, and Example 3-1 in which the washing solvent is isopropanol, the size of the AgBr peak decreased as the polarity of the washing solvent increased. It can be seen that AgBr is well removed when a washing solvent having a large polarity is used.

Hereinafter, electrical characteristics such as current-voltage curve and resistance and mechanical characteristics such as gauge factor of the above embodiments are as follows.

3. Electrical/mechanical property evaluation

A summary of the resistance according to the type of the substituted solvent and the washing solvent of Examples 1-1 to 3-3 is shown in Table 2 below.

[Table 2]

Referring to Table 2, when comparing the resistance of Examples 1-1 to 1-3 according to the type of exchange solvent when the same washing solvent is used, in the case of Example 1-1, 3.4Х10 ^-5 ±6.7Х10 ^It can be seen that the highest resistance of -6 Ωcm is shown, and in the case of Example 1-3, the lowest resistance of ^{7.2Х10 -6} ±8.3Х10 ^{-7 Ωcm is shown.}

When the resistance of the nanoparticle thin film according to the type of washing solvent is compared when the same solvent is used, it can be seen that the resistance of the nanoparticle thin film according to the type of the exchange solvent shows a tendency opposite to that of the nanoparticle thin film.

Specifically, it was confirmed that Example 1-1 had ^{the lowest resistance of 3.4 Х10 -5} ±6.7 Х10 ^-6 Ωcm, and Example 3-1 had the highest resistance of 1.9±1.2 Ωcm. I can.

Therefore, when the same washing solvent is used, when the polarity of the substitution solvent is low, it can be confirmed that the resistance of the nanoparticle thin film is decreased due to crack formation according to the ligand substitution rate.

In addition, when the same substitution solvent is used, when the polarity of the washing solvent is low, the second ligand composition on the surface of the silver nanoparticles increases, so that the resistance of the nanoparticle thin film increases, and accordingly, the gauge factor increases.

12A is a graph showing the current-voltage curve of the nanoparticle thin film according to the type of the substituted solvent of the embodiment of the present invention, and FIG. 12B is the current-voltage curve of the nanoparticle thin film according to the type of the cleaning solvent of the embodiment of the present invention. It is a graph showing.

First, referring to FIG. 12A, in the case of Example 1-1 of Examples 1-1 to 1-3, the slope of the graph (the reciprocal of resistance, 1/R) was considered to be the smallest, so that Example 1- It can be seen that the resistance of 1 is the largest.

In addition, as the graph slope value increases in the order of Examples 1-2 and 1-3, it can be seen that the resistance value decreases in the order of Examples 1-2 and 1-3.

Referring to FIG. 12B, in the case of Example 1-1 of Example 1-1, Example 2-1, and Example 3-1, when the same voltage was used, the current value was considered to be the largest, so that the resistance was the smallest. I can confirm.

In addition, since the current value at the same voltage in the order of Example 2-1 and Example 3-1 is considered to be large, it can be seen that the resistance value is large in the order of Example 2-1 and Example 3-1.

13A is a graph showing a change in resistance according to the type of a substituted solvent in an embodiment of the present invention, and FIG. 13B is a graph showing a change in resistance according to the type of a washing solvent in an embodiment of the present invention.

At this time, the time corresponding to the x-axis of FIG. 13A means the ligand substitution time, and the time corresponding to the x-axis of FIG. 13B means the washing time.

In this case, the cleaning time refers to a time from the time when the substrate on which the second nanoparticle layer is formed is started to be loaded in the cleaning solvent to the time when the substrate washed with the cleaning solvent is removed.

First of all, referring to FIG. 13A, in the case of Example 1-1 of Examples 1-1 to 1-3, the initial resistance value was the largest, and the resistance value was the largest for the same ligand substitution time. I can confirm.

In addition, it can be seen that the initial resistance values are higher in the order of Examples 1-2 and 1-3, and Examples 1-3 have the smallest resistance values for the same ligand substitution time.

Referring to FIG. 13B, it is considered that the rate at which the resistance decreases as the washing time increases in the case of Example 3-1 among Examples 1-1, 2-1, and 3-1 is the slowest. It can be seen that the second ligand removal rate of Example 3-1 is the slowest.

In addition, as the washing time increases in the order of Example 2-1 and Example 1-1, the rate at which the resistance decreases is slow, and the rate of decrease in the resistance of Example 1-1 is considered to be the fastest. It can be seen that the removal rate of the second ligand of 1-1 is the fastest.

14A and 14B are graphs showing voltage versus current according to whether or not strain is applied for each type of substitution solvent in an embodiment of the present invention, and FIG. 14C is a graph showing a change in resistance according to the number of bendings for each type of substitution solvent in an embodiment of the present invention. It is a graph.

First, referring to FIG. 14A, it can be seen that the current value in the case of applying strain (ε=1.0%) is smaller than the case in which the strain is not applied to the same voltage (ε=0%) in Example 1-1. .

Accordingly, when strain is applied to Example 1-1, it can be seen that the resistance is increased by 12.2%, and accordingly, when strain is applied, the gauge factor is 12.2.

Referring to FIG. 14B, it can be seen that the current value when strain is applied (ε=1.0%) is slightly smaller than when strain is applied to the same voltage (ε=0%) in Example 1-3. have.

Accordingly, it can be seen that the resistance is increased by 3.4% when the strain is applied to Examples 1-3, and accordingly, when the strain is applied, the gauge factor is 3.4.

Therefore, it can be seen that when the polarity of the substitution solvent is high, the resistance is greatly increased and thus high sensitivity is shown.

Referring to FIG. 14C, it is confirmed that the resistance change rate (y-axis) constantly increases and decreases according to the number of deformations (number of x-axis) of the nanoparticle thin film for Examples 1-1 to 1-3. I can.

At this time, the gauge factor of Example 1-1 was 12.4±0.4, the gauge factor of Example 1-2 was 9.2±0.8, and the gauge factor of Example 1-3 was 3.1±0.4.

Accordingly, when the same washing solvent is used, it can be seen that the greater the polarity of the replacement solvent, the greater the resistance, and the gauge factor increases.

15A and 15B are graphs showing current versus voltage according to whether or not strain is applied for each type of washing solvent in an embodiment of the present invention, and FIG. 15C is a graph showing a change in resistance according to the number of bending for each type of washing solvent in an embodiment of the present invention. It is a graph.

First, referring to FIG. 15A, it can be seen that the current value when strain is applied (ε=1.0%) is smaller than when strain is applied to the same voltage (ε=0%) in Example 1-1. .

Accordingly, when strain is applied to Example 1-1, it can be seen that the resistance is increased by 12.2%, and accordingly, when strain is applied, the gauge factor is 12.2.

Referring to FIG. 15B, it can be seen that the current value in the case where the strain is applied (ε = 1.0%) is much smaller than the case in which the strain is not applied to the same voltage (ε = 0%) in Example 3-1.

Accordingly, when strain is applied to Example 3-1, it can be seen that the resistance is increased by 77.2%. Accordingly, when strain is applied, the gauge factor is 77.2.

Therefore, it can be seen that when the polarity of the washing solvent is low in the same substituted solvent, the resistance is greatly increased and thus high sensitivity is shown.

Referring to FIG. 15C, with respect to Example 1-1, Example 2-1, and Example 3-1, the rate of change of resistance (y-axis) was constantly increased according to the number of deformations (number of x-axis) of the nanoparticle thin film, and It can be seen that the decrease is repeated.

In addition, as the resistance change rate of Example 3-1 is the largest and the resistance change rate of Example 1-1 is the smallest, when the same substitution solvent is used, the lower the polarity of the washing solvent, the greater the gauge factor of the nanoparticle thin film. Can be confirmed.

16 is a graph showing a current-voltage curve for each strain of a nanoparticle thin film according to an embodiment of the present invention.

Referring to FIG. 16, it can be seen that when a strain of 0.4% is applied to Example 1-3, the resistance increases by 132.5%.

Accordingly, when the polarity of the replacement solvent is low and the polarity of the cleaning solvent is high, a large number of cracks are formed, and the second ligand composition attached to the silver nanoparticle surface decreases, and the resistance and gauge factor increase, so that the nanoparticle thin film detects deformation very sensitively. can do.

17 is a graph showing hysteresis according to whether or not strain is applied to a nanoparticle thin film according to an embodiment of the present invention.

Referring to FIG. 17, it can be seen that the nanoparticle thin film of the present invention has a stable response as it has negligible hysteresis depending on whether or not strain is applied to Examples 1-3.

18 is a graph showing a change in resistance according to a strain size of a nanoparticle thin film according to an embodiment of the present invention.

Referring to FIG. 18, as the applied strain increased in Examples 1-3, the resistance change appeared linearly, and accordingly, as the strain was applied to the nanoparticle thin film of the present invention, the gauge factor increased and thus the sensitivity. It can be seen that is improved.

19 is a graph showing a change in resistance when strain-release of a nanoparticle thin film according to an embodiment of the present invention is repeated 1000 times.

Referring to FIG. 19, it can be seen that when the strain-release was repeated on the nanoparticle thin film 1000 times for Example 1-3, the resistance change rate was constantly increased and decreased.

Accordingly, it can be seen that the nanoparticle thin film of the present invention has excellent durability and reliability even in repeated bending.

20 is a graph showing a change in resistance according to a finger movement of a nanoparticle thin film according to an embodiment of the present invention.

Referring to FIG. 20, it can be seen that resistance increases when the nanoparticle thin film of Examples 1-3 attached to the finger is bent, and resistance is restored again when the finger is returned to its original state.

Accordingly, it can be confirmed that the nanoparticle thin film of the present invention has high sensitivity to deformation.

21 is a graph showing a change in resistance according to a sound wave of a nanoparticle thin film according to an embodiment of the present invention.

21 is an evaluation of the sound wave sensing ability of the nanoparticle thin film of Example 1-3 using sound waves generated by a Bluetooth speaker and a real drum application program.

Referring to FIG. 21, it can be seen that when a vibration sound (Tom) is applied to Example 1-3, the sensor vibrates and the resistance change rate (y-axis) changes.

When the sound ending with a single impact is applied (Kick), it can be seen that the nanoparticle thin film of Example 1-3 is bent upward to generate compressive stress, and the resistance change rate decreases.

Accordingly, it can be seen that the nanoparticle thin film of the present invention exhibits a fast response time as well as high sensitivity.

As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited to the above embodiments, and various modifications and variations from these descriptions for those of ordinary skill in the field to which the present invention pertains. This is possible. Therefore, the scope of the present invention is limited to the described embodiments and should not be defined, but should be defined by the claims to be described later as well as those equivalent to the claims.

100, 200: nanoparticle thin film
101: first area
102: second area
110: substrate
111: Kapton tape
120, 220: first nanoparticle layer
121: conductive nanoparticles
122: first ligand
123: second ligand

Claims (14)

Forming a first nanoparticle layer by applying a solution containing conductive nanoparticles surrounded by a first ligand on a substrate;
Forming a second nanoparticle layer in which the first ligand is substituted with the second ligand by supporting the substrate and the first nanoparticle layer in a ligand substitution solution containing a second ligand and a substitution solvent;
And preparing a nanoparticle thin film from which the second ligand has been removed by supporting the substrate and the second nanoparticle layer in a cleaning solvent.
The method of claim 1,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the resistance and the gauge factor of the nanoparticle thin film are adjusted according to the time for substituting the first ligand with the second ligand.
The method of claim 2,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the time for substituting the first ligand with the second ligand is 10 seconds to 120 seconds.
The method of claim 1,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the resistance and the gauge factor of the nanoparticle thin film are adjusted according to the time to remove the second ligand.
The method of claim 4,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the time for removing the second ligand is 10 seconds to 120 seconds.
The method of claim 1,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the resistance of the nanoparticle thin film ^{is adjusted to 6.37x10 -6 Ωcm to 3.1Ωcm.}
The method of claim 1,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the gauge factor of the nanoparticle thin film is adjusted to 3.1 to 400.
The method of claim 1,
The method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, wherein the substitution solvent is at least one of methanol, ethanol, and isopropanol.
The method of claim 1,
The washing solvent is a method of manufacturing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that at least one of methanol, ethanol, and isopropanol.
The method of claim 1,
The first ligand is a nanoparticle with controlled mechanical and electrical properties, characterized in that it contains at least one of trioctylphosphineoxide (TOPO), octadecanol, oleic acid, and oleylamine. Method of manufacturing a thin film.
The method of claim 1,
The second ligand is MPA (3-mercaptopropionic acid), EDT (1,2-ethanedithiol), EDA (ethylenediamine), sulfur ion (S ^2-), chloride ion (Cl ^-), bromide ion (Br ^-), thio cyanate ion (SCN ^-), iodine ion (I ^-), disulfide ion (HS ^-), tellurium ions (Te ^2-), hydroxide ions (OH ^-), boric tetrafluoride ion (BF ₄ ^-), and the method of at least any one of the nanoparticle thin film has mechanical and electrical properties control comprising ^the-six hexafluorophosphate ion (PF _6).
The method of claim 1,
The conductive nanoparticles contain at least one of gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), nickel (Ni), tungsten (W), and iron (Fe). Method for producing a nanoparticle thin film with controlled mechanical and electrical properties, characterized in that.
Conductivity in which the first ligand is substituted with the second ligand using a ligand substitution solution containing a second ligand and a substitution solvent, and the second ligand is removed using a washing solvent. In the nanoparticle thin film comprising nanoparticles,
The substitution solvent is isopropanol and the washing solvent is methanol,
The nanoparticle thin film is used as an electrode because the conductive nanoparticles are densely concentrated,
The resistance of the nanoparticle thin film used as the electrode is 6.37x10 ^-6 Ωcm to 8.03x10 ^-6 Ωcm, characterized in that the mechanical and electrical properties are controlled nanoparticle thin film.
Conductivity in which the first ligand is substituted with the second ligand using a ligand substitution solution containing a second ligand and a substitution solvent, and the second ligand is removed using a washing solvent. In the nanoparticle thin film comprising nanoparticles,
The substitution solvent is methanol and the washing solvent is isopropanol,
The nanoparticle thin film is used as an active layer including cracks on the surface,
The nanoparticle thin film with controlled mechanical and electrical properties, characterized in that the resistance of the nanoparticle thin film used as the active layer is 0.7Ωcm to 3.1Ωcm.

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