CN109390403B

CN109390403B - Graphene transistor, preparation method and use method thereof and self-driven electronic skin

Info

Publication number: CN109390403B
Application number: CN201710683047.6A
Authority: CN
Inventors: 孙其君; 孟艳芳; 张弛; 赵俊青
Original assignee: Beijing Institute of Nanoenergy and Nanosystems
Current assignee: Beijing Institute of Nanoenergy and Nanosystems
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2022-08-26
Anticipated expiration: 2037-08-10
Also published as: CN109390403A

Abstract

A graphene transistor, a preparation method and a use method thereof, and a self-driven electronic skin, wherein the graphene transistor comprises a substrate layer, an electrode layer, a graphene layer and an ion gel dielectric layer, wherein: the electrode layer comprises a source electrode and a drain electrode which are formed on the same surface of the substrate layer and are independently distributed; the graphene layer is positioned on the upper surfaces of the source electrode and the drain electrode and is in contact with the source electrode and the drain electrode; the ionic gel dielectric layer is located on the upper surface of the graphene layer. According to the self-driven electronic skin, graphene is used as a transistor, a grid-source drain-channel coplanar structure is realized, grid voltage is provided by direct friction on an ionic gel dielectric layer, the self-driven electronic skin can be used as a self-driven electronic skin, and the self-driven electronic skin has the characteristics of compact structure, low operating voltage, high regulation and control precision and high sensitivity.

Description

Graphene transistor, preparation method and use method thereof and self-driven electronic skin

Technical Field

The disclosure belongs to the field of semiconductor devices, and more particularly relates to a graphene transistor and a preparation method thereof, and a use method and a self-driven electronic skin of the graphene transistor.

Background

The electronic skin system is an electronic device or an electronic system which is manufactured by using a new material technology, a sensor technology and a micro-electro-mechanical processing technology and can simulate the functions of human skin such as protection, perception, regulation and the like. The main goals of electronic skin are:

1. the flexible film is flexible and can be tightly attached to a human body;

2. intelligence: signals (temperature, blood pressure and pulse) of human activities can be sensed with high sensitivity to obtain quantitative parameter information;

3. systematicness: can quickly respond to the change of the external environment and can make feedback.

In order to satisfy the high sensitivity and high resolution of the electronic skin detection environment and device integration, the research of Field Effect Transistor (FET) -based electronic skin is of great significance. The active matrix type electronic skin based on the transistor has the advantages of multi-parameter monitoring, high sensitivity, high resolution monitoring, high integration degree and the like, occupies a great position in the research and development of the electronic skin, and can accurately detect temperature, pressure, stress and multiple parameters.

However, in the transistor operation process, the gate and drain voltages need to be applied simultaneously, and although the optimized design of the active matrix has greatly reduced the operation energy consumption, due to the limitation of the traditional gate insulating layer material, the operation voltage of the active matrix electronic skin is mostly higher than 5V, and when the electronic skin is worn or even implanted into a human body, certain safety hazards and inconvenience exist.

Furthermore, because conventional wearable electronic skins rely on external power supplies, long wires are installed, limiting mobility applications. Therefore, the self-driven (without continuous power supply or intermittent charging) flexible electronic skin meets the important requirements of wearable portable monitoring of human activities, and the application of the flexible electronic skin can be greatly expanded. The conversion of mechanical energy into electrical energy is generally achieved by piezoelectric and triboelectric, wherein piezoelectric nanogenerators are applied to transistors based on ionic gel dielectric layers, resulting in piezoelectric self-driven electronic skins, which have been successfully developed. However, the research of the electronic skin based on piezoelectric self-driving still has certain problems, firstly, the effective induction area of the electronic skin is concentrated on the nanometer generator part, and the array space cannot be fully utilized; secondly, the voltage provided by the nano-generator cannot be used to effectively regulate the carrier concentration of the channel. Therefore, the development of more efficient self-driven electronic skins is a next problem to be solved.

Disclosure of Invention

Based on the above problems, a main objective of the present disclosure is to provide a graphene transistor, a method for manufacturing the same, and a self-driven electronic skin, which are used to solve at least one of the above technical problems.

In order to achieve the above object, as one aspect of the present disclosure, the present disclosure proposes a graphene transistor including a substrate layer, an electrode layer, a graphene layer, and an ion gel dielectric layer, wherein: the electrode layer comprises a source electrode and a drain electrode which are formed on the same surface of the substrate layer and are independently distributed; the graphene layer is positioned on the upper surfaces of the source electrode and the drain electrode and is in contact with the source electrode and the drain electrode; the ionic gel dielectric layer is located on the upper surface of the graphene layer.

In some embodiments of the present disclosure, the electrode layer further includes a gate electrode located on the same side of the substrate layer as the source electrode and the drain electrode and distributed independently; the source electrode is positioned between the drain electrode and the grid electrode, and the graphene layer is not in contact with the grid electrode.

In some embodiments of the present disclosure, the ionic gel dielectric layer is in contact with the upper surface of the gate.

In some embodiments of the present disclosure, the above-mentioned electronic skin further comprises a protective coating layer on the upper surface of the ionic gel dielectric layer; preferably, the protective coating is a fluorine-containing coating.

In some embodiments of the present disclosure, the substrate layer is a flexible material, preferably comprising polyethylene terephthalate.

In some embodiments of the present disclosure, the host material of the electrode layer includes a metal or a semiconductor material, and preferably, the semiconductor material includes graphene.

In some embodiments of the present disclosure, the graphene layer covers upper surfaces of the source electrode and the drain electrode; preferably, two sides of the graphene layer are flush with the sides of the source electrode and the drain electrode.

In some embodiments of the present disclosure, the graphene layer is a single layer graphene.

In some embodiments of the present disclosure, the thickness of the electrode layer ranges from 40 nm to 100 nm; the thickness of the ionic gel dielectric layer is 300-1000 μm; the thickness of the protective coating is 100-300 μm.

In order to achieve the above object, as another aspect of the present disclosure, the present disclosure proposes a method for manufacturing a graphene transistor, including the steps of: preparing an electrode layer on a substrate, and photoetching the electrode layer to form an independent source electrode and an independent drain electrode; transferring a pre-prepared graphene layer to the upper surfaces of the source electrode and the drain electrode, wherein the graphene layer is in contact with the source electrode and the drain electrode; preparing an ionic gel dielectric layer on the graphene layer.

In some embodiments of the present disclosure, when the independent source electrode and the drain electrode are formed by photolithography, the electrode layer is further formed by photolithography, and the source electrode is located between the drain electrode and the gate electrode; an ion gel dielectric layer is also formed on the upper surface of the grid electrode, and the ion gel dielectric layer on the upper surface of the graphene layer are of an integral structure.

In some embodiments of the present disclosure, the following steps are further included after the ion gel dielectric layer is prepared on the graphene layer: preparing a protective coating, and coating the protective coating on the upper surface of the ionic gel dielectric layer; preferably, the protective coating is a fluorine-containing coating.

In some embodiments of the present disclosure, the above method of preparing a protective coating comprises: dissolving hydrophobic nano particles in a tetrafluorofuran solution, adding perfluorooctyl triethoxysilane and polydimethylsiloxane, and performing ultrasonic treatment to form a solution A; dissolving polydimethylsiloxane in a tetrafluorofuran solution to form a solution B; and mixing the solution A and the solution B, and then carrying out ultrasonic treatment to form a protective coating.

To achieve the above object, as yet another aspect of the present disclosure, the present disclosure proposes a method of using the above graphene transistor, wherein a gate voltage of the transistor is provided by rubbing the ionic gel dielectric layer or the protective coating layer with a rubbing material of positive or negative rubbing polarity.

In order to achieve the above object, as yet another aspect of the present disclosure, the present disclosure proposes a method of using the above graphene transistor, wherein a gate voltage of the transistor is provided by rubbing the ionic gel dielectric layer or the protective coating layer with a rubbing material of positive or negative rubbing polarity; alternatively, a gate voltage is applied to the gate.

To achieve the above object, as yet another aspect of the present disclosure, the present disclosure proposes a self-driven electronic skin comprising the graphene transistor described above, a friction-driven graphene transistor of an ionic gel dielectric layer or a protective coating layer with a friction material of positive or negative friction polarity, generating a sensing signal.

The graphene transistor, the preparation method thereof and the self-driven electronic skin provided by the disclosure have the following beneficial effects:

1. the graphene transistor disclosed by the invention does not need an additional electrode, breaks through the vertical structure of the traditional graphene transistor, and realizes a grid-source drain-channel coplanar structure, so that the space utilization rate is high;

2. an ionic gel dielectric layer is used as a grid electrode to form a double electric layer structure, so that the capacitance of the transistor is increased, the output voltage of friction power generation is high, and the current change rate generated in unit area is high;

3. graphene is adopted as a main material of a transistor, high-efficiency and durable ionic gel suitable for triboelectronics is developed, and self-driven electronic skin is constructed by using the ionic gel, so that the main standard of the electronic skin is met: the flexible film is flexible and can be tightly attached to a human body; intelligence: signals (temperature, blood pressure and pulse) of human activities can be sensed with high sensitivity to obtain quantitative parameter information; systematicness: the system can quickly respond to the change of the external environment and can feed back the change;

4. the self-driving is realized by adopting the ionic gel as the grid electrode, so that not only is the energy consumption saved, but also the direct friction is realized on the ionic gel dielectric layer, the space can be effectively utilized, and the materials are saved, so that the self-driving electronic skin has a compact structure, low operating voltage, high regulation and control precision and high sensitivity;

5. the fluorine-containing coating is coated on the ionic gel, so that the charge density is increased by utilizing the strong electron-attracting capacity of the fluorine-containing material, the output of friction power generation is increased, the durability of the ionic gel dielectric layer is improved, and the ionic gel dielectric layer meets the requirement of long-term use of electronic skin.

Drawings

Fig. 1 is a schematic structural diagram of a self-driven e-skin according to an embodiment of the disclosure.

Fig. 2(a) to 2(d) are schematic diagrams illustrating the operation of the self-driven e-skin in fig. 1.

Fig. 3 is a schematic structural diagram of a self-driven e-skin according to another embodiment of the present disclosure.

Fig. 4(a) to 4(d) are schematic diagrams illustrating the operation of the self-driven electronic skin in fig. 3.

Fig. 5(a) is a transfer curve of a graphene transistor in self-driven electron skin in example 1.

Fig. 5(b) is a transfer curve of graphene transistors under triboelectric generator friction in self-driven electronic skin in example 1.

Fig. 5(c) is an output curve of the graphene transistor in the self-driven electron skin in example 1.

FIG. 5(d) is the I-V curve of the self-driving electronic skin friction generator of example 1 rubbed different distances.

Fig. 6(a) is a transfer curve of graphene transistors in self-driven electron skin in example 2.

Fig. 6(b) is a transfer curve of the ionic gel dielectric layer of the graphene transistor in the self-driven electronic skin under friction with the positive friction electrode sequence material in example 2.

Fig. 6(c) is an output curve of the graphene transistor in the self-driven e-skin in example 2.

Fig. 6(d) is an I-V curve of the graphene transistor in the self-driven electronic skin in example 2 when the ionic gel dielectric layer and the positive rubbing electrode sequence material are rubbed at different distances.

Fig. 6(e) is a graph showing the change of the current of the graphene transistor in self-driven electronic skin with time when the current of the graphene transistor is rubbed back and forth with the positive-friction electrode material in example 2.

Fig. 6(f) is a time-dependent variation curve of the current of the graphene transistor in the self-driven electronic skin after the ionic gel dielectric layer and the positive friction electrode sequence material are rubbed back and forth 100 times in example 2.

Fig. 7(a) is a transfer curve of graphene transistors in self-driven electron skin in example 3.

Fig. 7(b) is a transfer curve under friction of the ionic gel dielectric layer of the graphene transistor in the self-driven electronic skin and the positive friction electrode sequence material in example 3.

Fig. 7(c) is an output curve of the graphene transistor in the self-driven electron skin in example 3.

Fig. 7(d) is the I-V curve of the self-driven electrodermal graphene transistor of example 3 when the ionogel dielectric layer is rubbed with the positive-rubbing electrode sequence material at different distances.

Fig. 7(e) is a graph showing the change of the transistor current with time under the reciprocal friction of the ionic gel dielectric layer and the positive friction electrode sequence material of the self-driven electronic skin graphene transistor in example 3.

Fig. 7(f) is a time-dependent variation curve of the current of the graphene transistor in the self-driven electronic skin after 3000 times of reciprocal frictions between the ionic gel dielectric layer and the positive friction electrode sequence material in example 3.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

In 2012, a triboelectric nanogenerator was developed which can convert mechanical energy into electrical energy in view of the coupling effect of friction and electrostatic induction. The friction generator (TENG) utilizes two materials with different triboelectric polarities to contact with each other and generate triboelectric charges on the surface, and a potential difference is generated during separation, so that current output is formed on an external circuit.

Triboelectric generators can also be combined with conventional field effect transistors to obtain contact field effect transistors, on the basis of which triboelectronics have been developed. In a field effect transistor, the semiconductor layer conduction channel width and carrier concentration are controlled by an applied gate voltage to regulate the source-drain current. In triboelectronics, TENG replaces gate voltage to regulate the source-drain current of a device, and the mechanical energy of the external environment directly controls the source-drain current. Because the field effect transistor is used for the electronic skin, the human body activity monitoring with high sensitivity and high accuracy can be realized, the friction nanoelectronics combined by the friction generator and the transistor is applied to the electronic skin, new advantages of self-driving, accurate controllability and integration are added to the advantages of the field effect transistor, and the field effect transistor can be used for personal medical treatment and man-machine interaction. For example, a wearable self-driven bionic membrane based on friction nano generator driving has the advantages of light weight, low cost, easy preparation, multiple functions and the like.

In order to make up for the high energy consumption requirement of the current electronic skin on external voltage and provide a theoretical and practical basis for developing safe and reliable self-driven implantable devices in the future, the electric double layer transistor driven by the electrostatic potential generated by the friction nano generator and the basic logic device thereof are researched in the disclosure, and the self-driven electronic skin based on the triboelectronics is developed on the basis. Therefore, the electronic skin developed by the application has obvious innovation in the fields of human health treatment and human-computer interaction feedback.

Thus, as shown in fig. 1, the present disclosure proposes a graphene transistor comprising a substrate layer 101, an electrode layer, a graphene layer 105 and an ion gel dielectric layer 106, wherein: the electrode layer comprises a source electrode 103 and a drain electrode 102 which are formed on the same surface of the substrate layer and are independently distributed; the graphene layer 105 is positioned on the upper surfaces of the source electrode 103 and the drain electrode 102, and two side edges of the graphene layer are flush with the side edges of the source electrode 103 and the drain electrode 102 respectively; an ionic gel dielectric layer 106 is located on the upper surface of the graphene layer 105.

In some embodiments of the present disclosure, the electrode layer further includes a gate 104 disposed on the same side of the substrate layer 101 as the source 103 and the drain 102, wherein the source 103 is disposed between the drain 102 and the gate 104; while the ionic gel dielectric layer 106 is in contact with the upper surface of the gate 104. Therefore, the graphene transistor disclosed by the invention does not need an additional electrode, breaks through the vertical structure of the traditional graphene transistor, and realizes a gate-source drain-channel coplanar structure, so that the space utilization rate is high.

Based on the graphene transistor, the present disclosure also provides a method for manufacturing a graphene transistor, including the following steps: preparing an electrode layer on a substrate, and photoetching the electrode layer to form an independent source electrode and an independent drain electrode; transferring a pre-prepared graphene layer to the upper surfaces of the source electrode and the drain electrode, wherein the graphene layer is in contact with the source electrode and the drain electrode; and preparing an ionic gel dielectric layer on the graphene layer.

In some embodiments of the present disclosure, in the step of preparing the electrode layer on the substrate, the electrode layer is further formed with a gate by photolithography, and the source is located between the drain and the gate; in the step of preparing the ion gel dielectric layer on the graphene layer, the ion gel dielectric layer is also formed on the upper surface of the grid electrode and is integrated with the ion gel dielectric layer on the upper surface of the graphene layer.

In some embodiments of the present disclosure, the graphene layer covers the upper surfaces of the source and the drain, and preferably, two side edges of the graphene layer are flush with the side edges of the source and the drain, respectively, so that a good contact can be formed, and the performance of the graphene transistor is improved.

In some embodiments of the present disclosure, a protective coating, preferably a fluorine-containing coating, is further formed on the upper surface of the ionic gel dielectric layer, so that not only is the charge density increased by utilizing the strong electron-attracting ability of the fluorine-containing material, but also the output of frictional electricity generation is increased, and the durability of the ionic gel dielectric layer is improved, so that the ionic gel dielectric layer can meet the requirement of long-term use of electronic skin.

As shown in fig. 1, based on the graphene transistor, in some embodiments of the present disclosure, a self-driven electronic skin is further provided, which includes a friction generator, and the graphene transistor is described above, in which either of two friction layers of the friction generator is connected to the gate 104, and the self-driven electronic skin is friction-driven by two

friction layers

201, 202 of the friction generator. Wherein, the thickness of two

friction layers

201, 202 in the friction generator is about 300-1000 μm, and the length is about 2-5 cm. The self-driven electronic skin constructed by the method meets the main standards of the electronic skin: the flexible film is flexible and can be tightly attached to a human body; intelligence: signals (temperature, blood pressure and pulse) of human activities can be sensed with high sensitivity to obtain quantitative parameter information; systematicness: can quickly respond to the change of the external environment and can make feedback.

The self-driven electronic skin is friction-driven by two

friction layers

201 and 202 of the friction generator, and other power supplies can be connected with the grid 104 to provide grid voltage for the graphene transistor. Alternatively, the gate voltage of the transistor is provided by rubbing the ionic gel layer or protective coating with a rubbing material of positive or negative rubbing polarity.

In some embodiments of the present disclosure, the substrate layer is a flexible material; preferably flexible polyethylene terephthalate (PET).

In some embodiments of the present disclosure, the host material of the electrode layer includes a metal or a semiconductor material, and the semiconductor material includes graphene.

In some embodiments of the present disclosure, the method for manufacturing a graphene transistor may further include a step of depositing a graphene layer on the upper surface of the copper foil, including: and putting the cleaned and dried copper foil into a vacuum quartz tube, introducing hydrogen into the vacuum quartz tube, heating at a high temperature for a period of time, introducing methane gas while introducing the hydrogen, reacting to generate graphene, and gradually depositing the graphene to the upper surface of the copper foil to obtain the graphene layer.

In some embodiments of the present disclosure, in a method of fabricating a graphene transistor, the step of fabricating an ionic gel dielectric layer on a graphene layer includes: mixing 1-ethyl-3-methylimidazoline bis (trifluoromethylsulfonyl) imide and polyethylene glycol diacrylate monomers with a mass ratio of 90:8:2 with a 2-hydroxy-2-methyl propyl phenyl ketone mixed solution and a photoinitiator 2-methyl propyl phenyl ketone to form an ionic gel liquid; and adding ionic gel liquid on the upper surface of the graphene layer, and forming an ionic gel dielectric layer after mask exposure under ultraviolet light.

In some embodiments of the present disclosure, the base layer has a thickness of about 5mm and a length of 1-3 cm; the thickness of the source, drain and gate (i.e. electrode layer) is about 40-100 nm; the thickness of the ionic gel dielectric layer is about 300-1000 μm, and the length is about 2-5 mm.

The method adopts transparent single-layer graphene with high toughness and excellent electrical property as a main material of a transistor, develops high-efficiency durable ionic gel suitable for triboelectronics, and selects and optimizes a corresponding friction material, so as to construct a graphene-based double-layer transistor (GFET) in the triboelectronics. In the present invention, a single graphene layer is preferably used as the graphene layer.

As shown in fig. 2(a) to 2(d), the specific working principle of the self-driven electronic skin is described in detail by taking the self-driven electronic skin including a contact-separation type friction generator (without being limited thereto, the friction generator can also be of any other type of structure), in which when dielectric layer materials with different triboelectric polarities (positive triboelectric electrode sequence material and negative triboelectric electrode sequence material) are in contact, opposite charges are respectively induced on the surfaces; due to the electrostatic balance, no charge flows and no influence is exerted on the transistor (see fig. 2(a) and 2 (c)). When the negative friction electrode material 201 is separated from the positive friction electrode material 202 by a small distance, the electrostatic attraction needs to be overcome to generate a potential difference. As shown in fig. 2(b), when positive rubbing electrode sequence material 202 is connected to grid 104, grid 104 induces negative charges in order to balance the negative charges on the surface of the positive rubbing electrode sequence material, and ionic gel dielectric layer 106 becomes an electric double layer. The interface of the gate 104/the ionic gel dielectric layer 106, and the interface of the ionic gel dielectric layer 106/the graphene layer 105 have negative and positive ions respectively arranged in a directional manner. Due to the negative ions oriented at the interface of the ionic gel dielectric layer 106/graphene layer 105, it is equivalent to providing a negative gate voltage to the graphene layer 105, resulting in a decrease in the fermi level of graphene. As shown in fig. 2(d), when the positive friction electrode material 201 is connected to the grid electrode 106, the grid electrode 104 induces a negative charge in order to balance the positive charges on the surface of the positive friction electrode material, and the ionic gel dielectric layer 106 becomes an electric double layer. The interface of the gate 104/the ionic gel dielectric layer 106, and the interface of the ionic gel dielectric layer 106/the graphene layer 105 have positive and negative ions respectively arranged in a directional manner. Due to the positive ion orientation at the interface of the ionic gel dielectric layer 106/graphene layer 105, it is equivalent to providing a positive gate voltage to the graphene, resulting in an increase in the fermi level of the graphene.

As shown in fig. 3, the present disclosure also provides a graphene transistor. The graphene transistor is different from the graphene transistor shown in fig. 1 in that: the ion gel dielectric layer is used as a gate. Referring to fig. 3, the graphene transistor includes a substrate layer 101, an electrode layer, a graphene layer 105, and an ion gel dielectric layer 106, wherein: the electrode layer comprises a source electrode 103 and a drain electrode 102 which are formed on the same surface of the substrate layer and are independently distributed; the graphene layer 105 is positioned on the upper surfaces of the source electrode 103 and the drain electrode 102, and two side edges of the graphene layer are flush with the side edges of the source electrode 103 and the drain electrode 102 respectively; the ionic gel dielectric layer 106 is positioned on the upper surface of the graphene layer 105; the graphene transistor further comprises a protective coating 107 on the upper surface of the ionic gel dielectric layer; preferably, the protective coating 107 is a fluorine-containing coating.

In use of the transistor, the gate voltage of the transistor is provided by rubbing the ionic gel layer or protective coating with a rubbing material of positive or negative rubbing polarity.

For the graphene transistor including the gate 104 in the electrode layer, the gate voltage may be provided by a friction voltage rubbed by the two rubbing

layers

201 and 202 of the rubbing generator, or another power source such as a dc power source may be connected to the gate 104 to provide the gate voltage for the graphene transistor. Alternatively, the gate voltage of the transistor is provided by rubbing the ionic gel layer or protective coating with a rubbing material of positive or negative rubbing polarity.

The self-driven electronic skin adopts the ionic gel as the grid electrode to realize self-driving, so that energy consumption is saved, direct friction is realized on the ionic gel, space can be effectively utilized, materials are saved, and the self-driven electronic skin has the advantages of compact structure, low operating voltage, high regulation and control precision and high sensitivity.

In some embodiments of the present disclosure, the method for manufacturing the graphene transistor specifically may include the following steps: step 1, depositing a graphene layer on the upper surface of a copper foil; step 2, preparing an electrode layer on the substrate, and photoetching the electrode layer to form an independent source electrode and an independent drain electrode; step 3, dissolving the copper foil after spin-coating a chlorobenzene solution of methyl methacrylate on the graphene layer, transferring the graphene layer to the upper surfaces of the source electrode and the drain electrode, and washing away the chlorobenzene solution of methyl methacrylate; step 4, preparing an ionic gel dielectric layer on the graphene layer; and preparing a protective coating on the ionic gel dielectric layer and applying the protective coating to the upper surface of the ionic gel dielectric layer. When the graphene layer is transferred to the upper surfaces of the source electrode and the drain electrode, two side edges of the graphene layer are flush with the side edges of the source electrode and the drain electrode respectively. The protective coating is preferably a fluorine-containing coating.

In some embodiments of the present disclosure, the above method of preparing a protective coating comprises: dissolving hydrophobic nano particles in a tetrafluorofuran solution, adding perfluorooctyl triethoxysilane (FAS) and polydimethylsiloxane, and performing ultrasonic treatment to form a solution A; dissolving polydimethylsiloxane in a tetrafluorofuran solution to form a solution B; and mixing the solution A and the solution B, and then carrying out ultrasonic treatment to form a protective coating. Preferably, the protective coating has a thickness of about 100 to 300 μm and a length of about 2 to 5 mm.

The fluorine-containing coating is coated on the ionic gel, so that the charge density is increased by utilizing the strong electron-attracting capacity of the fluorine-containing material, the output of friction power generation is increased, the durability of the ionic gel dielectric layer is improved, and the ionic gel dielectric layer meets the requirement of long-term use of electronic skin.

When the negative/positive rubbing electrode pattern material 201 contacts the protective coating 107 on the ionic gel dielectric layer, as shown in fig. 4(a) or fig. 4(c), the surface is respectively charged with negative positive charges due to the difference of the rubbing electrode patterns; at this time, because of charge balance, no charge transfer occurs between the ionic gel dielectric layer 106 and the graphene layer 105, and no current flows. As shown in fig. 4(b), when the negative triboelectric polarity material 201 is separated from the protective coating 107, in order to balance the positive charge on the surface of the protective coating 107, electrons at the interface of the protective coating 107 and the ionic gel dielectric layer 106 move to the surface, attracting negatively charged ions in the ionic liquid of the ionic gel dielectric layer 106 due to electrostatic induction, leaving a negative charge at the interface of the ionic gel dielectric layer 106 and the protective coating 107 in contact. While positively charged ions in the ionic gel dielectric layer 106 move to the graphene layer 105/ionic gel dielectric layer 106 interface, forming an electric double layer (i.e., helmholtz face). Due to the positive ions oriented at the interface of the ionic gel dielectric layer 106/graphene layer 105, it is equivalent to providing a positive gate voltage to the graphene layer, resulting in the increase of the fermi level of graphene.

As shown in fig. 4(d), when the positive friction electrode sequence material 201 is separated from the protective coating layer 107 on the ionic gel dielectric layer 106, in order to balance the negative charges on the surface of the protective coating layer 107, the holes at the contact interface of the protective coating layer 107 and the ionic gel dielectric layer 106 move to the surface, and due to electrostatic induction, attract the positively charged ions in the ionic gel dielectric layer 106, so that the contact interface of the protective coating layer 107 and the ionic gel dielectric layer 106 remains positively charged. While negatively charged ions in the ionogel dielectric layer 106 move to the graphene layer 105/ionogel dielectric layer 106 interface, forming an electric double layer (i.e., helmholtz plane). Due to the oriented negative ions at the interface of the ionic gel dielectric layer 106/graphene layer 105, it is equivalent to providing negative gate voltage to graphene, resulting in the decrease of the fermi level of graphene.

Based on the graphene transistor, the self-driven electronic skin is further provided, and the friction between the ionic gel dielectric layer or the protective coating of the transistor and the friction material with positive or negative friction polarity provides a gate voltage to drive the transistor to generate a sensing signal.

In some embodiments of the present disclosure, a method for preparing a self-driven electronic skin based on a triboelectronic two-layer graphene transistor is provided, which comprises the following steps:

step A, preparing single-layer graphene by chemical vapor deposition;

copper foil (10 cm. times.10 cm, 25 μm, Sigma) was first treated with piranha solution (H) ₂ SO ₄ And H ₂ O ₂ Mixed solution of (2) for 15min, the copper foil was soaked in deionized water and dried with nitrogen. Then adding it into quartz tube with air exhausted, when the internal pressure of quartz tube reaches 5X 10 ⁻³ When the temperature is Torr, H is introduced ₂ Simultaneously heating the quartz tube to 1000 ℃ for 30min, and continuously introducing H ₂ (flow rate 10 sccm), CH (hydrogen chloride) is introduced at a flow rate of 5sccm ₄ Gas, so that graphene grows continuously. After 30min, the CH introduction is stopped ₄ The quartz tube is in H ₂ Cooling the solution to room temperature in the flow to obtain the graphene growing on the copper foil.

Step B, preparing an electrode layer;

ultrasonic cleaning a substrate (silicon wafer or PET) in acetone, isopropanol and deionized water for 5min, plating a 50nm gold layer by a thermal evaporation method, and photoetching the gold layer by an ultraviolet exposure machine to form a metal layer comprising a source electrode, a drain electrode and/or a grid electrode.

Step C, preparing a graphene semiconductor layer;

and (3) spinning and coating a chlorobenzene solution of methyl methacrylate (PMMA) on the graphene growing on the copper foil, performing plasma etching on the back surface to remove the graphene on the back surface, and soaking the graphene in ammonium persulfate for 3 hours to dissolve copper. And transferring the PMMA/graphene layer completely dissolved with the copper to a substrate, washing PMMA on the graphene with acetone, and photoetching the graphene layer with an ultraviolet exposure machine to enable two side edges of the graphene layer to be flush with the side edges of the source electrode and the drain electrode respectively.

Step D, preparing an electric double layer of the ionic gel grid;

the ionic gel liquid is prepared from a mixed solution of ionic liquid 1-ethyl-3-methylimidazoline bis (trifluoromethylsulfonyl) imide ([ EMIM ] [ TFSI ]), monomer polyethylene glycol diacrylate monomer (PEGDA) and 2-hydroxy-2-methyl propyl phenyl ketone, photoinitiator 2-methyl propyl phenyl ketone (HOMPP) according to the mass ratio of 90:8:2, mixing the components.

A transparent adhesive tape is used for enclosing a substrate into a groove shape, ionic gel is added in the middle, and the substrate is exposed for 10 seconds by a mask under ultraviolet light. Under ultraviolet light, initiating agent HOMPP to generate free radicals to react with acrylate to initiate polymerization of monomer PEG-DA; the non-transparent part is not polymerized and can be washed away by deionized water.

Step E, preparing and coating a protective coating;

preparation of the protective coating: dispersing 5ml of tetraethyl orthosilicate (TEOS) and (0.5-2 ml) of perfluorooctyltriethoxysilane (FAS) in 25ml of ethanol at normal temperature, gradually dropwise adding 25ml of ethanol solution containing 6ml of 28% ammonia water into the solution, and violently stirring the solution at the rotation speed of 500-700 rpm/s for 10 hours to obtain the hydrophobic sol solution. Centrifuging and then drying in vacuum to obtain hydrophobic nano particles;

dissolving 0.9g of hydrophobic nanoparticles in 20-40ml of Tetrafluorofuran (THF), adding 0.6-1.5 g of perfluorooctyltriethoxysilane (FAS) and 0.4-0.8 g of Polydimethylsiloxane (PDMS), and performing ultrasonic treatment for 1 hour to obtain a solution A; 0.04-0.08g of PDMS curing agent, model sylgard184, was dissolved in 20-40ml of THF to form solution B. When the protective coating is used, the solution A, B is mixed, ultrasonic treatment is carried out for 15-30 min, the surface of the ionic gel dielectric layer is coated, and the protective coating is formed after 2-3 h at the temperature of 60 ℃.

There are two forms of rubbing in this embodiment to provide the gate voltage to the transistor: (1) an external triboelectric generator provides a gate voltage (electrode layer includes grid), (2) an ionic gel dielectric layer as a tribo layer provides a gate voltage (electrode layer does not include grid); it should be noted that: in the first case, the ionic gel dielectric layer may be free of a protective coating, and in the second case, a protective coating is applied.

According to the method, when the external friction generator provides the gate voltage, the sensitivity and the accuracy of the application of triboelectronics to the double-electric-layer gate dielectric transistor can be explored, and a foundation and a guarantee are provided for the intelligence and the systematicness of the electronic skin; when the ionic gel is used as a friction layer to provide gate voltage, a foundation and guarantee are provided for the integration of the electronic skin; preferably, the performance of the friction generator driving transistor with the PET as the flexible substrate provides a foundation and guarantee for the fitness and the wearability of electronic skin.

In some embodiments of the present disclosure, based on the semi-metal (semi-metallic) characteristics of graphene, it can be used not only as a channel material of a transistor, but also as a gate electrode, a source electrode, and a drain electrode, and an electrode layer can be replaced by a graphene electrode, which can simplify the process.

In some embodiments of the present disclosure, a self-driven e-skin based triboelectronic two-layer graphene transistor, the tribolayer comprising a triboelectric positive electrode order material, such as copper foil, aluminum foil, nylon, silk, and/or wool; the materials with negative electrode friction sequence comprise polytetrafluoroethylene, polyvinyl fluoride (PVC), Polydimethylsiloxane (PDMS) and/or polyimide.

According to the graphene transistor, the friction between the ionic gel dielectric layer or the protective coating and the positive or negative friction electrode material can provide grid voltage to drive the transistor, so that a sensing signal is generated, and the graphene transistor can be used as a self-driven electronic skin and applied to the field of intelligent sensing. The graphene transistor, the method for manufacturing the same, and the self-driven electronic skin proposed by the present disclosure are described in detail by specific embodiments below.

Example 1

This example presents a self-driven electron skin that provides gate voltage via the electrical properties of graphene transistors and an externally applied triboelectric generator (open circuit voltage of 2V).

The graphene transistor comprises a substrate layer, an electrode layer, a graphene layer and an ion gel dielectric layer, wherein: the electrode layer comprises a source electrode, a drain electrode and a grid electrode which are formed on the same surface of the substrate layer and are independently distributed, and the source electrode is positioned between the drain electrode and the grid electrode; the graphene layer is positioned on the upper surfaces of the source electrode and the drain electrode, and two side edges of the graphene layer are respectively flush with the side edges of the source electrode and the drain electrode; the ionic gel dielectric layer is located on the upper surfaces of the graphene layer and the grid, and part of the ionic gel dielectric layer is in contact with the grid.

And fixing the friction generator on a displacement table which is accurately positioned, and respectively connecting the output end of the friction generator with the grid electrode and the grounding end of the transistor. Initially, the two contact friction layers of the friction generator are completely contacted, and the displacement table is controlled by a program to move equidistantly according to the designed displacement, so that the two contact friction layers of the friction generator are separated equidistantly.

As shown in fig. 5(a), the transfer curve of the graphene transistor under different source-drain voltages is an approximate parabolic shape, which indicates that the graphene is a bipolar transmission characteristic; and the operating voltage can be regulated and controlled only at 2V, which shows that the larger capacitance of the ionic gel dielectric layer reduces the operating voltage.

As shown in FIG. 5(b), for the friction generator, Polytetrafluoroethylene (PTFE) and copper are used as friction materials, the PTFE is grounded, the copper is in contact with a gate electrode of a graphene transistor, and the transfer curve (V) of the graphene transistor is changed gradually when the distance between friction contact layers of the friction generator is changed gradually _ds = 0.1V), the Drain current (I) is known _d ) One by oneThe step change indicates that the triboelectric generator can function well as a gate to provide a gate voltage to the transistor. And the distance between the two triboelectric layers of the triboelectric generator increases, the larger the triboelectric generator potential, the larger the gate voltage applied to the transistor. According to the schematic diagram of fig. 2(b), when the positive copper in the rubbing electrode sequence is in contact with the gate electrode of the graphene transistor, the negative gate voltage is applied to the transistor, and the increase of the negative gate voltage with the increase of the distance promotes the increase of the hole concentration in the graphene channel, I _d And also increases.

As shown in fig. 5(c), the output curves of the graphene transistor at different gate voltages are shown. From the graph, the leakage current I _d And the drain voltage V _ds And a better linear relation is presented, which indicates that the contact between the graphene layer and the source electrode and the drain electrode is better. At the same time, I _d With the gate voltage V _g The increase in absolute value indicates that the greater the gate voltage, the more pronounced the modulation of the transistor's carrier transport.

As shown in fig. 5(d), the output curve of the transistor is measured when the friction between the two contact friction layers of the generator is measured. At the initial moment, the contact friction layers of the friction generator are completely contacted, and due to different triboelectric negativity, opposite charges are respectively induced on the surfaces. However, due to charge balance, no gate voltage is supplied to the transistor, and therefore the transistor's I _d Lower. When the two surfaces are separated by a small distance of 50 [ mu ] m, the I of the transistor _d And (4) improving. In order to balance the surface charges, charge movement is generated, a potential difference is generated, and the output end of the friction generator is respectively connected with the grid electrode and the grounding end of the transistor, so that the friction generator provides grid voltage for the transistor. Comparing fig. 5(d) with fig. 5(c), it is found that the curve change trends are consistent, and the change step pitch and the change distance of the grid voltage by 100 μm are consistent with the change of the absolute value of the grid voltage by 0.05V. The curve in FIG. 5(d) shows I _d And V _ds Exhibit a better linear relationship between them, I _d The distance increases with the relative movement distance of the two friction contact layers of the friction generator, which shows that the friction generator can be used as a grid to provide grid voltage for a transistor well, and the distance increases due to frictionThe larger the electrostatic potential generated by the generator is, the larger the gate voltage applied to the transistor is, and the more obvious the regulation and control on the carrier transmission of the transistor are.

Comparing the above frictional and electrical properties shows that: the double-layer transistor based on triboelectronics has stability and meets the practical requirements of self-driven electronic skins.

Example 2

In order to realize integration of triboelectronics and double-electric-layer gate dielectric transistors, the embodiment provides a self-driven electronic skin, which comprises a friction material and a graphene transistor, wherein an ionic gel dielectric layer is used as one of friction layers to be in contact with and separated from the friction material with positive or negative friction polarity, and gate voltage is provided for the transistor. The friction materials with different friction electronegativities of positive and negative are respectively selected.

The graphene transistor comprises a substrate layer, an electrode layer, a graphene layer, an ion gel dielectric layer and a protective coating, wherein: the electrode layer comprises a source electrode and a drain electrode which are formed on the same surface of the substrate layer and are independently distributed; the graphene layer is positioned on the upper surfaces of the source electrode and the drain electrode, and two side edges of the graphene layer are flush with the side edges of the source electrode and the drain electrode respectively; the ionic gel dielectric layer is positioned on the upper surface of the graphene layer; the protective coating is located on the upper surface of the graphene layer.

Through the contact separation of the friction material and the protective coating, the ionic gel dielectric layer is used as an electric double layer, positive/negative ions are gathered on the interface between the ionic gel dielectric layer and the graphene layer, and therefore gate voltage is provided for the graphene transistor, wherein the substrate layer is made of a silicon wafer.

Fig. 6(a) to 6(f) show response signals of graphene transistors when the friction material is directly rubbed with the ionic gel. The transistor (the source and drain electrodes are led out by silver paste to form a lead, and the lead is connected to a semiconductor tester) and the friction material are respectively fixed on two opposite surfaces of the precisely positioned displacement table. Initially, the friction material copper is in full contact with the ionic gel, and the displacement table is controlled by a program to move equidistantly according to the designed displacement, so that the friction material and the ionic gel dielectric layer are separated equidistantly.

As shown in fig. 6(a), a transfer curve of the graphene transistor under different source-drain voltages is in an approximate parabolic shape, which indicates that graphene is a bipolar transmission characteristic; and the operating voltage can be regulated and controlled only at 2V, which shows that the larger capacitance of the ionic gel dielectric layer reduces the operating voltage.

FIG. 6(b) shows the transfer curve of the graphene transistor (where the drain voltage is V) when the ionogel dielectric layer is rubbed with copper as a rubbing material with a positive rubbing electrode sequence _ds = 0.1V), it can be seen from the figure that the distance between the friction material and the graphene transistor is changed stepwise, I _d The gradual change shows that the ionic gel dielectric layer can be used as a grid electrode to provide a grid voltage for the transistor well, the distance between the friction material and the graphene transistor is increased, the larger the potential generated by friction is, the larger the grid voltage applied to the transistor is, and the I is increased along with the increase of the negative grid voltage due to the fact that the graphene is in hole transport _d Increasing; and it can be seen from the figure that the distance between the friction material and the graphene transistor changes by the same amount, I _d Change amount Δ I of _d Likewise, the stability of the electronic skin is shown to be better. The reason is that copper is arranged at the positive end in the sequence of the rubbing electric polarity, and is in contact with the ionic gel dielectric layer to lose electrons, so that negative charges are carried on the interface of the ionic gel dielectric layer and the protective coating, and the negative charges are induced on the interface between the ionic gel dielectric layer and the graphene layer, which is equivalent to applying negative gate voltage to the graphene transistor.

The output curves of the graphene transistor at different gate voltages are shown in fig. 6(c), which shows I _d And V _ds And a better linear relation is presented, which shows that the contact between the graphene and the source and drain electrodes is better. At the same time, I _d With the absolute value of V _g The absolute value increases. Indicating that the larger the gate voltage, the more significant the regulation of the transistor carrier transport.

Fig. 6(d) shows the output curve of the transistor with different distances between the friction material and the graphene transistor. Initially, the friction material and the stoneThe graphene transistors are in full contact and due to the difference in triboelectric negativity, opposite charges are induced on the surfaces, respectively. However, due to charge balance, no gate voltage is supplied to the transistor, and therefore the transistor's I _d Lower. I of the transistor when the two surfaces are separated by a small distance of 50 [ mu ] m _d And (4) improving. In order to balance the surface charges, charge movement is generated, a potential difference is generated, and the output end of the friction generator is respectively connected with the grid electrode and the grounding end of the transistor, so that the friction generator provides grid voltage for the transistor. Comparing fig. 6(D) and fig. 6(c), it is found that the curve changes in a consistent manner, and that the change step pitch of the gate voltage, the distance between the friction material and the graphene transistor, changes by 100 μm each time, and the absolute value of the gate voltage changes by 0.05V each time (the values of D1 to D7 in the figure represent the distances, each interval increases by 100 μm), indicating that I _d And V _ds Exhibit a better linear relationship, I _d The distance between the friction material and the graphene transistor is increased, so that the ionic gel dielectric layer serving as the grid can well provide gate voltage for the transistor, the distance between the friction material and the graphene transistor is increased, the larger the electrostatic potential generated by the friction generator is, the larger the gate voltage applied to the transistor is, and the more obvious the regulation and control on the carrier transmission of the transistor are.

FIG. 6(e) shows the rubbing layer and the graphene transistor under reciprocal contact separation, I of the transistor _ds Curve over time, wherein V _ds =0.1V, it can be seen from the figure that with repeated contact separation between the friction layer and the graphene transistor, I _d Stable over time.

FIG. 6(f) shows I after 1000 contact separations _d The curve changes with time. In order to overcome the defect that the mechanical strength of the ionic gel dielectric layer is not ideal enough and the abrasion resistance is poor, and the long-term use of the ionic gel dielectric layer is influenced, a protective coating is coated on the ionic gel dielectric layer to increase the strength and the stability of the ionic gel dielectric layer. As can be seen in FIG. 6(f), the curve remained stable after 1000 repeated contact separations, I _d The peak does not change much with increasing number of iterations. Indicating that the electric double layer crystal is based on triboelectronicsThe tube is disclosed as having stability that meets the practical requirements of self-driven electronic skins.

Example 3

This example presents a self-driven e-skin that differs from example 2 only in that the base layer of this example employs polyethylene terephthalate (PET).

Since the electronic skin is practically applied to the human body, flexibility is one of the main targets of the electronic skin in order to meet the requirements of the surface shape of the human body. This example uses the flexible substrate PET for practical application of electronic skins.

Fig. 7(a) shows a transfer curve of a graphene transistor on a PET substrate under different source-drain voltages, and as can be seen from the graph, the curve is in an approximate parabolic shape, which indicates that graphene is a bipolar transmission characteristic; and the operating voltage can be regulated and controlled only at 2V, which shows that the larger capacitance of the ionic gel grid dielectric layer reduces the operating voltage.

FIG. 7(b) shows the transfer curve of a graphene transistor (at this time, the leakage current V is shown) on a PET substrate, with copper as a friction material with a positive electrode sequence _ds = 0.1V), it can be seen from the figure that the distance between the friction layer and the graphene transistor is changed stepwise, I _d The stepwise change shows that the ionogel dielectric layer can be used as a gate electrode to provide a gate voltage for the transistor well, and the distance is increased, and the larger the potential generated by triboelectric generation, the larger the gate voltage applied to the transistor. The material with positive rubbing electrode sequence rubs the ionic gel equivalently to provide negative grid voltage, and the graphene is used for hole transmission, and I is increased along with the increase of the negative grid voltage _d And is increased. The distance between the friction layer and the graphene transistor is changed by the same amount, I _d Change amount Δ I of _d Again, the stability was shown to be better.

Fig. 7(c) shows the output curves of the graphene transistor at different gate voltages on the PET substrate. The curve in the figure shows I _d And V _ds The graphene and the source and drain electrodes have good contact with each other. At the same time, I _d With the absolute value of V _g AbsoluteThe increase in value increases, indicating that the greater the gate voltage, the more pronounced the modulation of the transistor's carrier transport.

Fig. 7(d) shows the output curve of the transistor at different distances between the friction layer and the graphene transistor on the PET substrate, and comparing 7(d) with fig. 7(c), it is found that the curve has the same trend, and the change step pitch of the gate voltage, the change of the distance between the friction layer and the graphene transistor by 100 μm, and the trend of the change of the absolute value of the gate voltage by 0.5V are the same (the values of d1 to d4 in the figure represent the distances, and each interval is increased by 100 μm). I.e. the curve in the figure indicates I _d And V _ds Exhibit a better linear relationship between them, I _d The distance is increased, so that the ionic gel dielectric layer can be used as a grid electrode to provide a grid voltage for the transistor well, the distance between the friction layer and the graphene transistor is increased, the larger the potential generated by friction is, the larger the grid voltage applied to the transistor is, and the more obvious the regulation and control on the carrier transmission of the transistor are.

FIG. 7(e) shows the I of a graphene transistor on a PET substrate with the rubbing layer separated from the transistor by reciprocating contact _ds A time profile of V _ds = 0.1V. As can be seen, when the rubbing layer and the graphene transistor are repeatedly contacted and separated, I _d Stable over time.

FIG. 7(f) shows I after the rubbing layer is separated from the graphene transistor by 1000 times of reciprocal contact on the PET substrate _d The curve over time, as can be seen from the figure, remained stable after 3000 cycles, I _d The peak value does not change much with increasing cycle number. The disclosure of the triboelectronic-based electric double layer transistor is shown to have stability, meeting the practical requirements of self-driven electronic skins.

It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only directions referring to the drawings, and are not intended to limit the protection scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.

And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

Further, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. However, the disclosed method should not be construed to reflect the intent: that is, the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

1. A preparation method of a graphene transistor comprises the following steps:

preparing an electrode layer on a substrate, and photoetching the electrode layer to form an independent source electrode and an independent drain electrode;

transferring a pre-prepared graphene layer to upper surfaces of the source and drain electrodes, the graphene layer being in contact with the source and drain electrodes;

preparing an ionic gel dielectric layer on the graphene layer;

preparing a protective coating and applying the protective coating to the upper surface of the ionic gel dielectric layer;

when the photoetching is carried out to form the independent source electrode and the independent drain electrode, the electrode layer is also photoetched to form a grid electrode, and the source electrode is positioned between the drain electrode and the grid electrode;

wherein the protective coating is a fluorine-containing coating;

wherein the step of preparing the ionic gel dielectric layer on the graphene layer comprises: mixing 1-ethyl-3-methylimidazoline bis (trifluoromethylsulfonyl) imide, a polyethylene glycol diacrylate monomer, a 2-hydroxy-2-methyl propyl phenyl ketone mixed solution and a photoinitiator 2-methyl propyl phenyl ketone in a mass ratio of 90:8:2 to form an ionic gel liquid, adding the ionic gel liquid to the upper surface of the graphene layer, and performing mask exposure under ultraviolet light to form the ionic gel dielectric layer;

the ion gel dielectric layer is also formed on the upper surface of the grid electrode and is integrated with the ion gel dielectric layer on the upper surface of the graphene layer;

the thickness range of the electrode layer is 40-100 nm, the thickness of the ionic gel dielectric layer is 300-1000 mu m, the length of the ionic gel dielectric layer is 2-5 mm, the thickness of the protective coating layer is 100-300 mu m, and the length of the protective coating layer is 2-5 mm.

2. The method for manufacturing a graphene transistor according to claim 1, wherein the method for manufacturing a protective coating includes:

dissolving hydrophobic nano particles in a tetrahydrofuran solution, adding perfluorooctyl triethoxysilane and polydimethylsiloxane, and performing ultrasonic treatment to form a solution A;

dissolving polydimethylsiloxane in a tetrafluorofuran solution to form a solution B;

and mixing the solution A and the solution B, and then carrying out ultrasonic treatment to form the protective coating.

3. A graphene transistor prepared by the preparation method of the graphene transistor according to any one of claims 1-2, comprising a substrate layer, an electrode layer, a graphene layer and an ion gel dielectric layer, wherein:

the electrode layer comprises a source electrode and a drain electrode which are formed on the same surface of the substrate layer and are independently distributed;

the graphene layer is positioned on the upper surfaces of the source electrode and the drain electrode and is in contact with the source electrode and the drain electrode;

the ionic gel dielectric layer is located on the upper surface of the graphene layer.

4. The graphene transistor according to claim 3, wherein the electrode layer further comprises:

the grid electrode is positioned on the same side of the substrate layer as the source electrode and the drain electrode and is distributed independently;

the source electrode is located between the drain electrode and the grid electrode, and the graphene layer is not in contact with the grid electrode.

5. The graphene transistor according to claim 4, wherein the ionic gel dielectric layer is in contact with the gate upper surface.

6. The graphene transistor according to any one of claims 3 to 5, further comprising a protective coating on an upper surface of the ionic gel dielectric layer.

7. The graphene transistor according to claim 6, wherein the protective coating is a fluorine-containing coating.

8. The graphene transistor according to any one of claims 3 to 7, wherein the base layer is a flexible material.

9. The graphene transistor according to claim 8, wherein the base layer comprises polyethylene terephthalate.

10. The graphene transistor according to any one of claims 3 to 9, wherein the host material of the electrode layer comprises a metal or semiconductor material.

11. The graphene transistor according to claim 10, wherein the semiconductor material comprises graphene.

12. The graphene transistor according to any one of claims 3 to 11, wherein the graphene layer covers upper surfaces of the source and drain electrodes.

13. The graphene transistor according to claim 12, wherein two sides of the graphene layer are flush with sides of the source and drain electrodes.

14. The graphene transistor of any one of claims 3 to 13, wherein the graphene layer is single layer graphene.

15. A method of using the graphene transistor according to any one of claims 3, 6 to 14, wherein the ionic gel dielectric layer or protective coating is rubbed by a rubbing material of positive or negative rubbing polarity to provide the gate voltage of the transistor.

16. A method of using the graphene transistor according to any one of claims 4 to 14, wherein the ionic gel dielectric layer or protective coating is rubbed by a friction material of positive or negative rubbing polarity to provide a gate voltage of the transistor;

alternatively, a gate voltage is applied to the gate.

17. A self-driven e-skin comprising a graphene transistor as claimed in any one of claims 3 to 14, wherein rubbing of the ionic gel dielectric layer or protective coating with a rubbing material of positive or negative rubbing polarity drives the graphene transistor to generate a sensing signal.