KR20240018084A - Sustainable electronic device, manufacturing method thereof, and method for separating and recovering electrode and channel layer from sustainable electronic device - Google Patents

Abstract

The present invention relates to a sustainable electronic device that is biodegradable and recyclable and exhibits excellent electrical properties, a method of manufacturing the same, and a method of separating and recovering electrodes and channel layers from the sustainable electronic device. The present invention relates to a sustainable electronic device according to the present invention. is a cellulose composite that has dielectric properties and functions as a substrate and gate insulating film; A channel layer provided on one side of the cellulose composite; It is characterized by comprising a gate electrode, a source electrode, and a drain electrode provided on one side of the cellulose composite, wherein the cellulose composite is composed of a cellulose substrate with a porous structure, crystalline nanocellulose and salt immobilized on the cellulose substrate. and the salt exists in an ionic state.

Description

Sustainable electronic device, manufacturing method thereof, and method for separating and recovering electrode and channel layer from sustainable electronic device}

The present invention relates to a sustainable electronic device and its manufacturing method, and to a method for separating and recovering electrodes and channel layers from a sustainable electronic device. More specifically, a sustainable electronic device that is biodegradable and recyclable and exhibits excellent electrical properties. and a manufacturing method thereof and a method for separating and recovering electrodes and channel layers from sustainable electronic devices.

Recently, interest in sustainable electronics is increasing due to the demand and need for eco-friendliness. Currently, some parts of electronic devices are being recycled, but the majority of parts are disposed of, so there is always a possibility of environmental pollution by hazardous chemicals and toxic metals.

Most research on sustainable electronics focuses on biodegradability. For example, the substrates of electronic devices are being replaced with biodegradable substrates such as cellulose, or biodegradable materials are being applied to some parts. In contrast, recycling of electrodes and semiconductor materials that make up the chips of electronic devices is at a minimal level. In terms of components, the substrate accounts for 99% of electronic devices, but in terms of cost, components such as electrodes and semiconductor materials account for most of the cost of electronic devices. Therefore, in order to implement sustainable electronic devices, both biodegradation and recycling must be considered. In other words, parts of electronic devices must be designed to be biodegradable or recyclable.

In addition to achieving eco-friendly goals through biodegradation and recycling, sustainable electronic devices must ensure the performance of the electronic device itself. Even if biodegradation and recycling are possible, there are limits to creating demand for sustainable electronic devices if the performance of the electronic devices is not sufficient.

The reality is that electrical performance is lower than that of general electronic devices due to material characteristics, such as the application of cellulose as a substrate in consideration of biodegradation, and research is needed to overcome this.

U.S. Patent Publication No. US 2016-0198984 (published on July 14, 2016) Korean Patent Publication No. 2051213 (announced on December 3, 2019) Korean Patent Publication No. 2306356 (announced on September 30, 2021)

The present invention was devised to solve the above problems, and its purpose is to provide a sustainable electronic device that is biodegradable and recyclable and exhibits excellent electrical properties.

In addition, the present invention provides a method for manufacturing sustainable electronic devices, as well as a technology for separating electrodes and semiconductor materials from sustainable electronic devices and using the separated electrodes and semiconductor materials as components for sustainable electronic devices. There is another purpose.

A sustainable electronic device according to the present invention for achieving the above object includes a cellulose composite that has dielectric properties and functions as a substrate and a gate insulating film; A channel layer provided on one side of the cellulose composite; It is characterized by comprising a gate electrode, a source electrode, and a drain electrode provided on one side of the cellulose composite.

The cellulose composite is composed of a porous cellulose substrate, crystalline nanocellulose immobilized on the cellulose substrate, and a salt, and the salt exists in an ionic state.

A sustainable electronic device has I _ON greater than 9.6μA mm ^-1 per channel layer width, I _ON/OFF greater than 10 ² , and field effect mobility greater than 2.03cm ² V ^-1 s ^-1 under the condition of -0.5V gate voltage. .

The salt is NaCl, and the NaCl concentration is 10 ^-4 to ^{10 -2} M.

The channel layer is made of s-SWCNT, and the gate electrode, source electrode, and drain electrode are made of graphene.

A channel layer is provided on one side of the cellulose composite, a source electrode and a drain electrode are provided on both ends of the channel layer, and a gate electrode is provided on the other side of the cellulose composite, and the channel layer is made of s-SWCNT. Additionally, the gate electrode, source electrode, and drain electrode are made of graphene.

Crystalline nanocellulose is provided in a form that fills the pores of the cellulose substrate to reduce the surface roughness of the cellulose substrate, and the crystalline nanocellulose and the cellulose substrate form hydrogen bonds.

The method of manufacturing a sustainable electronic device according to the present invention includes forming a channel layer on one side of a cellulose substrate; Immobilizing crystalline nanocellulose and salt on a cellulose substrate; It includes forming a gate electrode, a source electrode, and a drain electrode on one side of the cellulose substrate, and immobilizing crystalline nanocellulose and salt on the cellulose substrate; forming crystalline nanocellulose on the other side of the cellulose substrate. It includes a process of coating the included slurry and a process of immersing the cellulose substrate on which crystalline nanocellulose is immobilized in an aqueous salt solution.

The method for separating and recovering electrodes and channel layers from sustainable electronic devices according to the present invention includes removing the channel layers and electrodes from sustainable electronic devices through ultrasonic treatment; Preparing an aqueous solution in which two types of polymers that are phase-separated due to thermodynamic instability are dissolved, and adding a mixture of the fallen channel layer material and the electrode material to the aqueous solution; And over a certain period of time, the two types of polymers are phase separated into an upper layer and a lower layer in an aqueous solution, and the channel layer material is moved to the upper layer and the electrode material is moved to the lower layer.

A surfactant is further added to the aqueous solution, and the surfactant may be added at a concentration of 0.03 to 0.2 wt%.

Dextran (DX) and polyethylene glycol (PEG) can be used as the above two types of polymers.

The sustainable electronic device, its manufacturing method, and the method of recovering parts from the sustainable electronic device according to the present invention have the following effects.

Not only can a high-performance field effect transistor be implemented, but the electrode and channel layers that make up the field effect transistor can be separated and recovered at a high recovery rate. These properties satisfy all of the biodegradability, recycling, and excellent electrical properties required for sustainable electronic devices.

1 is a schematic diagram of a sustainable electronic device according to an embodiment of the present invention.
Figure 2 is a flowchart illustrating a method of manufacturing a sustainable electronic device according to an embodiment of the present invention.
Figure 3 is a process schematic diagram for explaining a method of manufacturing a sustainable electronic device according to an embodiment of the present invention.
Figure 4 is a flowchart illustrating a method for separating and recovering electrodes and channel layers from a sustainable electronic device according to an embodiment of the present invention.
Figure 5 is a process schematic diagram illustrating a method for separating and recovering electrodes and channel layers from a sustainable electronic device according to an embodiment of the present invention.
Figure 6a is an SEM image of the surface of a cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to ^{10 0} M was applied.
Figure 6b is an atomic force microscopy (AFM) image of the surface of a cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to 10 ⁰ M was applied.
Figures 6c and 6d are TEM images of the surface of cellulose composite to which 10 ^-4 M NaCl was applied.
Figures 6e and 6f are X-ray diffraction results of a cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to ^{10 0} M was applied.
7A to 7C show output curve characteristics of the field effect transistor manufactured according to Experimental Example 1.
Figure 8a shows the IV curve according to NaCl molar concentration.
Figure 8b shows the capacitance characteristics of a field effect transistor to which different NaCl molar concentrations are applied according to frequency changes.
Figures 8c and 8d show I _ON/OFF characteristics and field effect mobility characteristics according to NaCl molar concentration of the field effect transistor manufactured in Experimental Example 1, respectively.
Figures 8e and 8f show a comparison of the I _ON characteristics and switching characteristics of the field effect transistor manufactured according to Experimental Example 1 and the existing transistor.
Figure 9 is a photograph showing the separation state of graphene and s-SWCNT according to the surfactant SC concentration.
Figures 10A to 10E show the recovery and regeneration characteristics of the electrode and channel layer according to Experimental Example 4.
Figures 11a to 11e show bending test results of the field effect transistor manufactured according to Experimental Example 1.

The present invention presents technology for sustainable electronic devices with excellent electrical properties and recovery technology for electrodes and semiconductor materials, which are components applied to sustainable electronic devices.

As previously described in 'Technology behind the invention', the requirements for a sustainable electronic device are excellent performance of the electronic device in addition to environmentally friendly factors such as biodegradation and recycling. Existing sustainable electronic devices Because the focus is on biodegradation, recycling of expensive parts such as electrodes and semiconductor materials is minimal, and the performance of the electronic device itself cannot overcome the limitations of materials.

The present invention presents a technology that can meet all requirements for sustainable electronic devices. Components applied to the sustainable electronic device according to the present invention are biodegradable or recyclable, and the sustainable electronic device according to the present invention ensures excellent electrical characteristics.

The sustainable electronic device of the present invention refers to a field effect transistor (FET), and may, for example, refer to an ion-gated field effect transistor (ion-gated FET).

In constructing the field effect transistor of the present invention, the most essential element is the application of cellulose composite as the substrate and gate insulating film. Additionally, in the field effect transistor of the present invention, carbon nanotubes (CNTs) are used as the channel layer, and graphene is used as the source/drain electrodes and gate electrodes.

As the electrical properties of carbon nanotubes and graphene are well known, it can be said that the electrical properties of the field effect transistor according to the present invention depend on the properties of the cellulose composite that simultaneously serves as the substrate and gate insulating film of the transistor. Of course, in order to optimize the electrical characteristics of a field-effect transistor, it is natural to optimize not only the cellulose composite itself, but also the geometric shape and physical properties of carbon nanotubes and graphene applied as the channel layer and electrode, respectively.

The cellulose composite applied to the field effect transistor of the present invention simultaneously performs the role of a substrate supporting the channel layer and electrode, and the role of a gate insulating film based on dielectric properties.

The cellulose complex applied to the present invention is a cellulose substrate coated with crystalline nanocellulose (CNC, crystalline nanocellulose) and doped with salt. Crystalline nanocellulose (CNC) fills the pores of the cellulose substrate and forms hydrogen bonds with the cellulose substrate to lower the surface roughness of the cellulose substrate. Lowering the surface roughness of the cellulose substrate means improved electrical properties. A salt doped into a cellulose substrate, such as NaCl, imparts dielectric properties to the cellulose substrate and induces amorphization of crystalline nanocellulose (CNC). NaCl doped into the cellulose substrate exists in the form of Na ⁺ and Cl ^- , and when a gate voltage is applied, Na ⁺ and Cl ^- are polarized by forming an electric double layer (EDL) to generate dielectric properties. In addition, amorphization of crystalline nanocellulose (CNC) is induced by salt, which increases the ion mobility of Na ⁺ and Cl ^- , thereby strengthening the polarization phenomenon of Na ⁺ and Cl ^- , thereby improving the dielectric properties of cellulose. .

In this way, by applying a cellulose composite that simultaneously performs the role of a substrate and a gate insulating film, the I _ON characteristics, I _ON/OFF , and field-effect mobility characteristics of the field-effect transistor can be improved, which will be described later. This is confirmed through an experimental example.

Meanwhile, the graphene applied as the source/drain electrode and the gate electrode, and the carbon nanotube applied as the channel layer can be separated and recovered respectively by aqueous two-phase extraction (ATPE), and the recovered graphene and Carbon nanotubes can be reapplied as electrodes and channel layers in sustainable electronic devices. In the experimental example described later, the application and recovery of graphene and carbon nanotubes to sustainable electronic devices were performed five times, and the recovery rate of graphene and carbon nanotubes reached about 90% at the fifth recovery.

Hereinafter, a sustainable electronic device, a method of manufacturing the same, and a method of recovering parts from a sustainable electronic device according to an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to Figure 1, a sustainable electronic device according to an embodiment of the present invention takes the form of a field effect transistor. To be precise, it takes the form of an ion-gated field effect transistor (ion-gated FET) with a back gate structure. As mentioned earlier, the sustainable electronic device according to the present invention refers to a field effect transistor, and an ion gate type field effect transistor is illustrated as an example, but it is satisfied to replace the substrate and gate insulating film of the transistor with a cellulose composite. Under the premise that field-effect transistors of various structures may be applicable to the sustainable electronic device of the present invention.

The sustainable electronic device shown in FIG. 1, that is, the field effect transistor, includes a cellulose composite and includes a channel layer and an electrode.

A channel layer is provided on one side of the cellulose composite, and source electrodes and drain electrodes are provided on both ends of the channel layer to be spaced apart from each other. Additionally, a gate electrode is provided on the other side of the cellulose composite.

The cellulose complex is composed of crystalline nanocellulose (CNC) and a salt, such as NaCl, on a cellulose substrate. The cellulose substrate is porous cellulose in the shape of a substrate, and as an example, cellulose filter paper (CFP, cellulose filter paper) can be used. Crystalline nanocellulose (CNC) is provided in a form that fills the pores of the cellulose base, and NaCl is dissociated and exists in the form of Na ⁺ and Cl ^- ions. Crystalline nanocellulose (CNC) is coated on a cellulose substrate in slurry form, and Na ⁺ and Cl ^- can be immobilized on the cellulose substrate by immersing the cellulose substrate in a NaCl solution. This will be explained in detail in the sustainable electronic device manufacturing method described later.

Crystalline nanocellulose (CNC) and salt immobilized on the cellulose substrate provide dielectric properties to the cellulose substrate and play a role in improving the electrical properties of the field-effect transistor.

Specifically, crystalline nanocellulose (CNC) is provided in a form that fills the pores of the cellulose substrate and forms hydrogen bonds with the cellulose substrate, and the surface roughness of the cellulose substrate is small due to the hydrogen bond between crystalline nanocellulose (CNC) and the cellulose substrate. Lose.

Salts doped into the cellulose substrate, such as NaCl, impart dielectric properties to the cellulose substrate. Na ⁺ and Cl ^- doped into the cellulose substrate are polarized by forming an electric double layer when a gate voltage is applied, thereby imparting dielectric properties to the cellulose substrate. In addition, Na ^{+ and} Cl ^- doped into the cellulose substrate induce amorphization of crystalline nanocellulose, and amorphization of crystalline nanocellulose (CNC) increases the ion mobility of Na ⁺ and Cl ^- . As the ion mobility of Na ⁺ and Cl ^- increases, the above-mentioned polarization phenomenon of Na ⁺ and Cl ^- is strengthened, thereby improving the dielectric properties of cellulose. The phenomenon of crystalline nanocellulose (CNC) becoming amorphous as the NaCl concentration increases can be confirmed through the This can be confirmed through an experimental example.

As dielectric properties are imparted to the cellulose composite, the cellulose composite can serve not only as a substrate for the transistor but also as a gate insulating film.

Meanwhile, the dielectric properties of the cellulose composite and the electrical properties of the field effect transistor vary depending on the concentration of NaCl doped into the cellulose substrate. Referring to the experimental examples described later, the capacitance of the cellulose composite tends to increase with increasing NaCl concentration, and in the case of I _ON/OFF characteristics, it rapidly decreases when the NaCl concentration exceeds 10 ^-4 M, and the electric field effect transfer In the case of degrees, optimal characteristics are shown when the NaCl concentration is in the range of 10 ^-4 to 10 ^-2 M, while when it exceeds 10 ^-2 M, the field effect mobility becomes very small. Based on these experimental results, considering the dielectric properties of the cellulose composite and the electrical properties of the field-effect transistor, a NaCl concentration of 10 ^-4 M is most desirable, and the next best solution is a NaCl concentration of 10 ^-4 to ^{10 -2.} It can be seen that even when the range M is applied, electrical characteristics are shown above a certain level.

The channel layer provided on one side of the cellulose composite may be composed of a carbon nanotube assembly with semiconductor properties. In one embodiment, the channel layer may be made of single-walled carbon nanotubes (s-SWCNTs) having semiconductor properties. Additionally, the source electrode and drain electrode provided on both ends of the channel layer, and the gate electrode provided on the other side of the cellulose composite may be made of graphene.

The channel layer made of single-walled carbon nanotubes (s-SWCNTs) is a factor that significantly affects the performance of the field-effect transistor, so it is necessary to optimize the density of the single-walled carbon nanotubes (s-SWCNTs) that make up the channel layer. There is. If the density of single-walled carbon nanotubes (s-SWCNT) is too high, I _OFF increases and I _ON/OFF decreases, while if the density is too low, a percolating network is not formed and a short occurs. It can be. In the experimental example described later, when forming a channel layer through a solution process, the width and length of the channel layer are specified as 5 mm and 3 mm, respectively, and the s-SWCNT concentration of 0.01 mg/ml is adjusted to 0.25 to 1 ml to form a single-walled layer. The density of carbon nanotubes (s-SWCNT) was controlled, and as a result, I _on/off was more than 10 ² at a gate voltage of -0.5V (at this time, I _ON was measured at 47.8 μA).

Above, a sustainable electronic device according to an embodiment of the present invention has been described. Next, a method for manufacturing a sustainable electronic device according to an embodiment of the present invention will be described.

First, prepare a cellulose substrate as shown in Figures 2 and 3 (S201). As an example, cellulose filter paper (CFP) can be used as a porous cellulose in the shape of a substrate. The thickness and pore size of the cellulose substrate are not particularly limited, but in the experimental examples described later, cellulose filter paper with a thickness of 40 μm and a pore size of 0.2 μm was used.

With the cellulose substrate prepared, a channel layer made of single-walled carbon nanotubes (s-SWCNT) with semiconductor properties is formed on one side of the cellulose substrate (S202). The channel layer, crystalline nanocellulose (CNC) described later, and electrode layer can all be formed through a solution-based process.

To form a channel layer, a single-walled carbon nanotube solution was prepared, and the single-walled carbon nanotube solution was filtered through a vacuum filtration device to form a channel layer made of single-walled carbon nanotubes (s-SWCNTs) on one side of the cellulose substrate. can be formed. As described above, the density of single-walled carbon nanotubes (s-SWCNTs) constituting the channel layer has a close influence on the electrical characteristics of the field-effect transistor of the present invention. In one embodiment, the density of s-SWCNTs at a concentration of 0.01 mg/ml -A channel layer made of single-walled carbon nanotubes (s-SWCNTs) can be formed by vacuum filtering 0.25 to 1 ml of the SWCNT solution.

With a channel layer made of single-walled carbon nanotubes (s-SWCNT) formed on one side of the cellulose substrate, a process of immobilizing crystalline nanocellulose (CNC) and salt on the cellulose substrate is performed (S203) (S204).

Specifically, a CNC slurry containing crystalline nanocellulose (CNC) at a certain concentration is prepared, and the CNC slurry is applied on the other side of the cellulose substrate to immobilize the crystalline nanocellulose (CNC) on the cellulose substrate (S203). The concentration of crystalline nanocellulose (CNC) in the CNC slurry can be set to 2 to 10 wt%. At this time, like the channel layer, crystalline nanocellulose (CNC) can be immobilized using vacuum filtration.

Crystalline nanocellulose (CNC) is immobilized in a form that fills the pores of the cellulose substrate, and the crystalline nanocellulose (CNC) and the cellulose substrate form hydrogen bonds. Hydrogen bonding between crystalline nanocellulose (CNC) and the cellulose substrate reduces the surface roughness of the cellulose substrate, improving the electrical properties of the field effect transistor.

When the crystalline nanocellulose (CNC) immobilization process is completed, the cellulose substrate on which the crystalline nanocellulose (CNC) is immobilized is immersed in a salt solution, for example, a NaCl solution (S204). Accordingly, the dissociated Na ⁺ and Cl ^- ions are doped into the cellulose substrate.

When a gate voltage is applied to the field effect transistor, the Na ⁺ and Cl ^- ions doped into the cellulose substrate are polarized by forming an electric double layer (EDL), giving dielectric properties to the cellulose substrate. At the same time, Na ⁺ and Cl ^- doped into the cellulose substrate induce amorphization of the crystalline nanocellulose, increasing the ion mobility of Na ⁺ and Cl ^- , thereby strengthening the dielectric properties of the cellulose substrate.

Through the immobilization process of crystalline nanocellulose (CNC) and salt as described above, a cellulose complex in which crystalline nanocellulose (CNC) and salt are immobilized on a cellulose substrate is formed. The cellulose composite not only serves as a substrate supporting the channel layer and electrode, but also serves as a gate insulating film as it is given dielectric properties as described above.

With the cellulose complex formed, the electrode formation process proceeds (S205). Specifically, a source electrode and a drain electrode are formed at each end of the channel layer, and a gate electrode is formed on the cellulose composite on the opposite side. The source electrode, drain electrode, and gate electrode are made of graphene, and the source electrode, drain electrode, and gate electrode can be formed by drop casting a solution in which graphene is dispersed.

Through the series of processes described above, the manufacture of a field effect transistor consisting of a cellulose composite, a channel layer, and an electrode, that is, a sustainable electronic device according to an embodiment of the present invention, is completed. At this time, the cellulose composite simultaneously serves as a substrate and a gate insulating film.

Above, a sustainable electronic device and its manufacturing method according to an embodiment of the present invention have been described. Below, a method for separating and recovering electrodes and channel layers from a sustainable electronic device according to an embodiment of the present invention will be described. FIG. 4 is a flowchart illustrating a method for separating and recovering electrodes and channel layers from a sustainable electronic device according to an embodiment of the present invention, and FIG. 5 is a flowchart illustrating an electrode and a channel layer from a sustainable electronic device according to an embodiment of the present invention. This is a process schematic diagram to explain how to separate and recover the channel layer.

Referring to FIG. 4, the process of extracting electrodes and channel layers from a sustainable electronic device is performed (S401).

Specifically, a sustainable electronic device is placed in an ultrasonic reaction tank and ultrasonicated to remove electrodes and channel layers from the sustainable electronic device. Then, the cellulose composite with the electrode and channel layer removed is taken out from the ultrasonic reaction tank. Here, the electrode is graphene, and the channel layer is single-walled carbon nanotube (s-SWCNT).

Meanwhile, since sustainable electronic devices contain salts and other substances in addition to electrodes and channel layers, ultrasonic treatment is performed again and centrifugation is performed to remove these salts and other substances. This ultrasonic treatment and centrifugation are repeated to remove salt components and other substances from the mixture of electrodes and channel layers. Through the above-described process, it is possible to obtain a mixture of an electrode and a channel layer from which impurities have been removed.

Once the extraction process of the electrode and channel layer is completed, the process of separating the electrode and channel layer is performed through aqueous two-phase extraction (ATPE).

With the two types of polymers that cause phase separation due to thermodynamic instability dissolved in water (S402), the mixture of the electrode and the channel layer and a certain amount of surfactant are added to the aqueous solution in which the two types of polymers are dissolved (S403). If left for some time (S404), the electrode and the channel layer are separated (S405).

Specifically, two types of polymers in an aqueous solution are phase separated into different layers due to thermodynamic instability after a certain period of time. For example, if two types of polymers, one is dextran (DX) and the other is polyethylene glycol (PEG), over time, dextran (DX) is located in the bottom layer of the solution and polyethylene glycol ( PEG) is located at the top layer of the solution. The bottom layer of the solution where dextran (DX) is located is relatively hydrophobic, and the top layer of the solution where polyethylene glycol (PEG) is located is relatively hydrophilic.

Meanwhile, the electrode and channel layer, that is, graphene and single-walled carbon nanotube, to be separated through the aqueous phase extraction method are separated in solution with the help of geometrical physical properties and surfactants. Because both graphene and single-walled carbon nanotubes are hydrophobic, they are not evenly dispersed in a solution in which dextran (DX) and polyethylene glycol (PEG) are dissolved. Therefore, the help of surfactants is needed to disperse and separate graphene and single-walled carbon nanotubes. In the presence of a surfactant, single-walled carbon nanotubes with one-dimensional physical properties move to the top layer of the solution, and graphene with two-dimensional physical properties move to the bottom layer of the solution.

The concentration of surfactant is a factor that has an important effect on the separation of graphene and single-walled carbon nanotubes. Referring to the experimental example described later, the experiment was conducted at concentrations of 0.02, 0.04, 0.05, and 0.2 wt% of the surfactant SC (sodium cholate hydrate), and as a result, separation of graphene and single-walled carbon nanotubes occurred when 0.05 wt% SC was applied. was the clearest, and when 0.2 wt% SC was applied, a phenomenon occurred in which graphene and single-walled carbon nanotubes were not separated but existed at the interface in a mixture state. In consideration of this point, the concentration of surfactant SC is preferably adjusted to 0.05 to 0.2 wt%.

When the single-walled carbon nanotubes and graphene are sequentially recovered from the solution while the graphene and the single-walled carbon nanotubes are separated by an aqueous phase extraction method, an electrode and a channel layer are produced from a sustainable electronic device according to an embodiment of the present invention. The method of separating and recovering is completed.

The separated and recovered graphene and single-walled carbon nanotubes can be reapplied as electrodes and channel layers of sustainable electronic devices. Referring to the experimental example described later, the recovery and application were repeated 5 times, resulting in approximately 90% of the original amount. The recovery rate is shown.

Above, a sustainable electronic device and its manufacturing method according to an embodiment of the present invention, and a method for separating and recovering electrodes and channel layers from a sustainable electronic device have been described. Hereinafter, the present invention will be described in more detail through experimental examples.

<Experimental Example 1: Fabrication of ion gate type field effect transistor>

The s-SWCNT solution with a concentration of 0.01 mg/ml was filtered through a vacuum filtration device to form an s-SWCNT thin film with a length of 3 mm and a width of 5 mm on the front surface of the cellulose filter paper. At this time, 0.25, 0.5, 0.75, and 1.0 ml of s-SWCNT solution were used to fabricate each transistor. Crystalline nanocellulose (CNC) slurry at a concentration of 5 wt% was coated on the front surface of the cellulose filter paper and dried at room temperature. Next, the cellulose filter paper was immersed in NaCl solution for 30 minutes. The molar concentration of the NaCl solution was applied differently within the range of 10 ^-5 to ^{10 0} M. Then, graphene was stacked on both ends of the s-SWCNT thin film using a drop casting method to form source and drain electrodes, and a gate electrode was formed on the back center of the cellulose filter paper using the same method. All of the above experiments were conducted at room temperature.

<Experimental Example 2: Cellulose composite characteristics according to NaCl molar concentration>

The surface and crystallinity of the cellulose composite produced according to Experimental Example 1 were examined.

Figure 6a is an SEM image of the surface of the cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to ^{10 0} M was applied, and as shown in Figure 6a, no porous structure was observed on the surface of the cellulose composite, showing a smooth surface. Able to know. This smooth surface is believed to be due to the formation of hydrogen bonds between the cellulose filter paper and crystalline nanocellulose (CNC).

Figure 6b shows an atomic force microscopy (AFM) image of the surface of a cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to ^{10 0} M was applied. In Figure 6b, it can be seen that the surface roughness of the cellulose composite to which only crystalline nanocellulose (CNC) is immobilized (leftmost figure in Figure 6b) is 35.5 nm, which is a pure cellulose substrate to which crystalline nanocellulose (CNC) and NaCl are not immobilized. Compared to the surface roughness of 563nm, it can be seen that it has been significantly reduced. Furthermore, it can be seen that as NaCl is added and the molar concentration of added NaCl increases, the surface roughness is also further reduced. When 10 ^-5 M NaCl was applied, the surface roughness was 23.6 nm, and at 10 ^-4 M and 10 ^-2 M, the surface roughness was 18.8 nm and 22.3 nm, respectively.

Figures 6c and 6d are TEM images of the surface of the cellulose composite to which 10 ^-4 M NaCl was applied, and it can be seen that crystalline cellulose (CNC) exists in a self-assembled form in a large area.

Figures 6e and 6f show the X-ray diffraction results of the cellulose composite to which NaCl molar concentration in the range of 10 ^-5 to ^{10 0} M was applied. It can be seen that the intensity of the X-ray diffraction peak decreases as the NaCl molar concentration increases. There is (see Figure 6e). In addition, it can be seen that 22.80°, one of the main peaks of crystalline nanocellulose (CNC), has moved to 22.65° as the NaCl molar concentration increases, which is believed to be the effect of Na ⁺ and Cl ^- ions.

<Experimental Example 3: Electrical characteristics of field effect transistor according to NaCl molar concentration>

The electrical characteristics of the field effect transistor manufactured according to Experimental Example 1 were examined.

_{The field} effect transistor (channel layer ^5mm ). Additionally, referring to the output curve (I _DS -V _DS ) of Figure 7b, it can be seen that the conductive path clearly moves at high positive values of V _GS . In addition, the dependence of I _ON/OFF on the channel layer width can be confirmed through Figure 7c.

Figure 8a shows the IV curve according to NaCl molar concentration, and it can be seen that it matches the characteristics of a typical p-type field effect transistor. Figure 8b shows the capacitance characteristics of a field effect transistor to which different NaCl molar concentrations are applied according to frequency changes. Figures 8c and 8d show the I _ON/OFF characteristics and field effect mobility characteristics of the field effect transistor manufactured in Experimental Example 1 according to NaCl molar concentration, respectively. Referring to Figures 8c and 8d, the I _ON/OFF characteristics rapidly increased from 1.6 to 40 at a molar concentration of 10 ^-5 M NaCl, and reached the highest value of 1.76 x 10 ² at a molar concentration of 10 ^-4 M. In addition, the field effect mobility at 10 ^-4 M molar concentration was 1.12 cm ² V ^-1 s ^-1 , and this field effect mobility value is a transfer curve with a capacitance value of 1.12 μF at -0.5V gate voltage. It is extrapolated from .

Meanwhile, as the molar concentration of NaCl was further increased, I _ON/OFF tended to rapidly decrease (I _ON/OFF was 0.11 x 10 ² and 0.12 x at 10 ^-2 M, 10 ^-1 M, and 10 ^-0 M, respectively. 10 ² , sharply decreased to 0.014 x 10 ² ). These results mean that when the concentration of salt ions in the cellulose complex increases, the I _ON characteristics improve, but the performance of the field effect transistor deteriorates. Considering the overall performance of the field effect transistor, the molar concentration of 10 ^-4 M NaCl is optimal. It is judged to indicate the performance of .

It can be seen that the I _ON characteristics and switching characteristics of the field effect transistor manufactured according to Experimental Example 1 show superior performance compared to existing transistors based on other materials (see Table 1 and Figures 8e and 8f).

<Comparison of characteristics of the field effect transistor manufactured according to Experimental Example 1 and existing transistors> Type of substrate Fabrication method Type of Device Semiconductor V _DS
(V) V _GS (V) On/off ratio ID
(uA/mm) Ref. Polyimide Printed and cleanroom method OTFT
(ion gel) DPh-BTBT -One One 10 ⁶ 0.9 ^One Polyimide Printed and cleanroom method OTFT
(ion gel) N1100 One One 10 ⁶ 0.5 ^One Glassine paper Printed OTFT
(ion gel) P3HT -One -2 10 ³ 20.6 ² Cotton fiber Cleanroom technique OTFT
(ion gel) DNNT One 3 10 ⁴ 4 ³ Cotton fiber Cleanroom technique OTFT
(ion gel) DNNT -2 -3 10 ⁵ 9 ⁴ Eucalyptus paper Cleanroom technique TFT
(double gate) IGZO One 30 10 ⁵ 145 ⁵ Si Printed Ion gel CNTs -1.4 -0.8 10 ⁵ 1300 ⁶ Polyimide Printed CNT-TFT CNTs 5 40 10 ⁴ 28.6 ⁷ Polyimide Printed CNT-TFT CNTs -5 -30 10 ⁴ 248 ⁸ Polyimide Printed CNT-TFT CNTs -5 -40 10 ⁶ One ⁹ Si Printed CNT-TFT CNTs -One -40 10 ⁴ 5.4 ¹⁰ Si Printed CNT-TFT CNTs -2 -40 10 ⁵ 24 ¹¹ Si Printed and cleanroom technique CNT-TFT CNTs One -20 10 ⁵ 17.6 ¹² Photo paper Printed CNT-TFT CNTs -2 -40 10 ⁵ One ¹³ CNTs embedded into cellulose Solution process CNT-TFT CNTs 9 5 10 ² - ¹⁴ PET Printed CNT-TFT CNTs -5 -14 10 ⁴ 48 ¹⁵ Si Printed OTFT CNTs -0.5 -25 10 ³ 5 ¹⁶ Paralyene_C Printed OTFT Merk silicon S1200 -10 -10 10 ⁶ 5.5 ¹⁷ PEN Printed and cleanroom technique OTFT P(NDI2OD-T2) 60 60 10 ⁴ 14 ¹⁸ PMMA Solution processed OTFT C8-BTBT -40 -40 10 ⁴ 28 ¹⁹ Polycarbonate Printed OTFT TIPS-Pentacene -60 -60 10 ⁵ - ²⁰ Printed paper Cleaning room technique and printing OTFT Pentacene and DNTT -80 -80 10 ⁸ 25 ²¹ Printed paper Printed OTFT pBTT -50 -50 10 ⁴ 37500 ²² Photo paper Cleanroom technique OTFT Pentacene -55 -55 10 ⁴ 5.8 ²³ Paper Cleanroom technique OTFT Pentacene One -5 10 ² 2 ²⁴ Paper Cleanroom technique OTFT GIZO 15 20 10 ⁴ 135 ²⁵ Paper Printed OTFT Poly(3,30000-didodecyl-quarterthiophene) -1.5 -2 15 28 ²⁶ PET-nanocellulose dielectric Cleanroom technique OTFT PCDTBT -50 -50 10 ⁴ 12 ²⁷ Nanocellulose paper Cleanroom technique OTFT GIZO 15 30 10 ⁵ 450 ²⁸ Nanocellulose paper Cleanroom technique OTFT GIZO 15 30 10 ⁴ 135 ²⁸ Photo paper Printed CNC-TFT
(ion gel) CNTs 0.5 2 10 ⁴ 87 ²⁹ Cellulose membrane filter paper Vacuum filtration technique - CNTs 0.5 2 176 9.6 this invention

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<Experimental Example 4: Recovery and regeneration characteristics of electrode and channel layer>

The electrode (graphene) and channel layer (s-SWCNT) were recovered from the field effect transistor manufactured according to Experimental Example 1, and the recovered graphene and s-SWCNT were applied to the process of Experimental Example 1 to produce a regenerated field effect transistor. It was manufactured and its electrical characteristics were examined.

Graphene and s-SWCNTs were recovered from the field effect transistor manufactured according to Experimental Example 1 by ultrasonic treatment, and impurities such as NaCl were removed through centrifugation.

Then, graphene and s-SWCNT were separated and recovered through aqueous phase extraction (ATPE). A mixture of graphene and s-SWCNT and the surfactant sodium cholate hydrate (SC) were added to an aqueous solution in which dextran (DX) and polyethylene glycol (PEG) were dissolved and left for a certain period of time. Surfactant SC was mixed at concentrations of 0.02, 0.04, 0.05, and 0.2 wt%, respectively (see Table 2 below).

<Mixture ratio of DX, PEG, graphene and s-SWCNT and surfactant> SC concentration DX(g) PEG(g) Graphene and s-SWCNT mixture DI water(g) 0.02wt% 10.8 4.32 0.48 8.4 0.04wt% 10.8 4.32 0.96 7.92 0.05wt% 10.8 4.32 1.2 7.68 0.2wt% 10.8 4.32 4.8 4.08

As a result of leaving, dextran (DX) and polyethylene glycol (PEG) are phase separated in the aqueous solution, so that polyethylene glycol (PEG) is located in the upper layer, dextran (DX) is located in the lower layer, and s-SWCNT is located in the upper layer of the aqueous solution. The graphene is moved to the lower layer and separated. Referring to Figure 9, when the surfactant SC concentration was 0.02 and 0.04 wt%, graphene and s-SWCNT remained in a mixture state, and when the surfactant SC concentration was 0.05 wt%, graphene and s-SWCNT were clearly separated. In the case of 0.2 wt%, graphene and s-SWCNT were not separated but existed at the interface in a mixture state.

Then, graphene and s-SWCNT were separated and recovered from the aqueous solution. Then, the separated and recovered graphene and s-SWCNT were used as electrodes and semiconductor layers, and a field effect transistor was manufactured by applying the same process as Experimental Example 1.

Figure 10a shows SEM and TEM images of recycled s-SWCNTs and new s-SWCNTs. As shown in Figure 10a, the chirality and single wall of s-SWCNTs are observed. ) can be confirmed to remain the same in the recovered s-SWCNT.

In addition, as a result of repeating the recovery of s-SWCNTs five times, it was confirmed through UV-vis analysis that nearly 90% of the initial recovery was recovered (see Figure 10b). Graphene also showed similar recovery rate results as s-SWCNT (see Figure 10c).

As a result of manufacturing a field-effect transistor using the recovered graphene and s-SWCNT as electrodes and channel layers and measuring the I _ON/OFF characteristics, the I _ON/OFF characteristics gradually deteriorated as recovery and regeneration were repeated (see Figure 10d). Meanwhile, it can be confirmed that the field effect transistor manufactured according to Experimental Example 1 shows a high I _ON/OFF value of 0.66 x 10 ² even after 30 days under a normal environment (see FIG. 10e).

<Experimental Example 5: Electrical characteristics during bending>

The bending stability of the field effect transistor manufactured according to Experimental Example 1 was analyzed.

As a result of bending the field effect transistor manufactured according to Experimental Example 1 at an angle range of 0 to 12° in the direction perpendicular to the electric field and examining the electrical characteristics (see FIG. 11a), the I _DS -V _GS curve showed p-type behavior. It can be seen that this is the case (see Figure 11b), and as the bending angle increases, I _ON decreases (see Figure 11c). Meanwhile, while I _ON decreases to 23.6 μA at a bending angle of 5° and 11.95 μA at a bending angle of 12°, it can be seen that I _OFF remains relatively constant regardless of the bending angle (see Figure 11d).

In addition, when the bending angle was restored to the initial state at a bending angle of 12°, that is, the bending angle was 0°, the I _ON value was also restored to the initial state (see Figure 11d). These characteristics mean that the sustainable electronic device according to the present invention can be fully utilized as a bending sensor.

In addition, as a result of conducting more than 600 bending fatigue tests within a bending angle of 5° (see Figure 11e), some deterioration occurred in I _ON and I _ON/OFF characteristics, but excellent performance was shown without serious structural damage.

Claims (14)

A cellulose composite that has dielectric properties and functions as a substrate and gate insulating film;
A channel layer provided on one side of the cellulose composite;
A sustainable electronic device comprising a gate electrode, a source electrode, and a drain electrode provided on one side of a cellulose composite.
The method of claim 1, wherein the cellulose complex,
A cellulose substrate with a porous structure,
It consists of crystalline nanocellulose and salt immobilized on the cellulose substrate,
A sustainable electronic device, characterized in that the salt exists in an ionic state.
The method of claim 1, wherein under the condition of -0.5V gate voltage, I _ON is 9.6 μA mm ^-1 or more per channel layer width, I _ON/OFF is 10 ² or more, and field effect mobility is 2.03 cm ² V ^-1 s ^-1 or more. A sustainable electronic device characterized by:
The sustainable electronic device of claim 2, wherein the salt is NaCl, and the NaCl concentration is 10 ^-4 to ^{10 -2} M.
The sustainable electronic device of claim 1, wherein the channel layer is made of s-SWCNT, and the gate electrode, source electrode, and drain electrode are made of graphene.
The method of claim 1, wherein a channel layer is provided on one side of the cellulose composite, a source electrode and a drain electrode are provided on both ends of the channel layer, respectively, and a gate electrode is provided on the other side of the cellulose composite,
A sustainable electronic device, wherein the channel layer is made of s-SWCNT, and the gate electrode, source electrode, and drain electrode are made of graphene.
The sustainable electronic device of claim 2, wherein the crystalline nanocellulose is provided to fill the pores of the cellulose substrate to reduce the surface roughness of the cellulose substrate, and the crystalline nanocellulose and the cellulose substrate form hydrogen bonds.
Forming a channel layer on one side of the cellulose substrate;
Immobilizing crystalline nanocellulose and salt on a cellulose substrate;
It includes the step of forming a gate electrode, a source electrode, and a drain electrode on one side of the cellulose substrate,
Immobilizing crystalline nanocellulose and salt on the cellulose substrate;
A process of coating a slurry containing crystalline nanocellulose on another side of a cellulose substrate;
A method of manufacturing a sustainable electronic device, comprising the process of immersing a cellulose substrate on which crystalline nanocellulose is immobilized in an aqueous salt solution.
The method of claim 8, wherein the salt is NaCl, and the NaCl concentration is 10 ^-4 to ^{10 -2} M.
The method of claim 8, wherein the channel layer is made of s-SWCNT, and the gate electrode, source electrode, and drain electrode are made of graphene.
removing the channel layer and electrodes from the sustainable electronic device through sonication;
Preparing an aqueous solution in which two types of polymers that are phase-separated due to thermodynamic instability are dissolved, and adding a mixture of the fallen channel layer material and the electrode material to the aqueous solution; and
Over a certain period of time, the two types of polymers are phase separated into an upper layer and a lower layer in an aqueous solution, and the channel layer material is moved to the upper layer and the electrode material is moved to the lower layer. A sustainable electronic device comprising: A method of separating and recovering the electrode and channel layer from.
The method of claim 11, wherein the channel layer material is s-SWCNT and the electrode material is graphene.
The method of claim 11, wherein a surfactant is further added to the aqueous solution,
A method for separating and recovering electrodes and channel layers from sustainable electronic devices, characterized in that the surfactant is added at a concentration of 0.03 to 0.2 wt%.
The method of claim 11, wherein the two types of polymers are dextran (DX) and polyethylene glycol (PEG).

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