An organic field effect transistor device and a method for fabricating the same

Abstract

The application belongs to the field of transistor devices, and discloses an organic field effect transistor device and a preparation method thereof. The preparation method comprises the following steps: preparing a covalent triazine organic framework nanosheet dispersion liquid by electrochemical exfoliation of a covalent triazine organic framework material, and standing; injecting the covalent triazine organic framework nanosheet dispersion liquid drop by drop onto the liquid surface of ultrapure water, and passing a SiO2 / Si substrate through the interface between the covalent triazine organic framework nanosheet and the ultrapure water to obtain a SiO2 / Si substrate containing triazine covalent organic framework nanosheets; and sequentially evaporating a chromium layer and a gold layer on the SiO2 / Si substrate containing triazine covalent organic framework nanosheets by using a vacuum thermal evaporation coating machine to obtain the organic field effect transistor device. The application is conducive to widening the application range of the organic field effect transistor device prepared according to the covalent triazine organic framework material.

Description

Technical Field

[0001] This invention belongs to the field of transistor devices, and more specifically, relates to an organic field-effect transistor device and its fabrication method. Background Technology

[0002] Covalent organic framework materials (COFs) are a class of periodic and crystalline porous organic polymers. Composed of lightweight elements linked by covalent bonds, COFs possess low density, high thermal stability, and inherent porosity, making them widely valued by researchers in fields such as gas adsorption, heterogeneous catalysis, and energy storage.

[0003] Since Yaghi synthesized the first covalent organic framework material in 2005, scientists have developed numerous organic chemical reactions for synthesizing covalent organic framework materials and have synthesized a large number of novel covalent organic framework materials. Based on the different linking groups, these covalent organic framework materials can be broadly classified into boric anhydride and borate ester series, Schiff base series, imine series, and triazine series, among others.

[0004] The synthesis of triazine-based covalent organic frameworks was first reported by Thomas's group in 2008, via a cyclization trimerization reaction of aromatic nitriles in molten zinc chloride at 400°C. Due to the high temperature required for the reaction, the number of suitable monomers is limited, and the triazine-based covalent organic frameworks exhibit low crystallinity, thus restricting their development and application. However, these materials possess high chemical stability, large specific surface area, and good semiconductor properties, making them promising organic polymer semiconductors. Triazine-based covalent organic frameworks, which can be formed under milder reaction conditions, exhibit higher crystallinity.

[0005] Therefore, there is an urgent need to propose a new method for fabricating organic field-effect transistor devices using triazine series covalent organic framework materials. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing an organic field-effect transistor device material and its fabrication method. This invention is beneficial for broadening the application scope of organic field-effect transistor devices fabricated based on covalent triazine organic framework materials.

[0007] To achieve the above objectives, the present invention provides a method for fabricating an organic field-effect transistor device, the method comprising the following steps:

[0008] S1: A dispersion of covalent triazine organic framework nanosheets was prepared by electrochemical exfoliation of covalent triazine organic framework material and allowed to stand.

[0009] S2: The covalent triazine organic framework nanosheet dispersion is injected dropwise onto the surface of ultrapure water, and the SiO2 / Si substrate is passed through the interface between the covalent triazine organic framework nanosheet and the ultrapure water to obtain a SiO2 / Si substrate containing triazine covalent organic framework nanosheet.

[0010] S3: Using a vacuum thermal evaporation coating machine, a chromium layer and a gold layer are sequentially deposited on the SiO2 / Si substrate containing triazine covalent organic framework nanosheets to obtain the organic field-effect transistor device (OFET).

[0011] According to the present invention, preferably, in step S1:

[0012] The covalent triazine organic framework material is a pure donor-type covalent triazine organic framework material (CTF-1) and / or a fluorinated donor-acceptor type covalent triazine framework material (F-CTFs);

[0013] The covalent triazine organic framework nanosheets are covalent triazine organic framework nanosheets with a lateral dimension ≥10μm;

[0014] The settling time is 0.5-1.5 hours.

[0015] According to the present invention, preferably, the method for preparing the covalent triazine organic framework material includes:

[0016] Place terephthalonitrile (DCB) and trifluoromethanesulfonic acid into a glass container, or place terephthalonitrile and 1,4-dicyanotetrafluorobenzene (DCTFB) into a glass container;

[0017] The glass container was subjected to freezing, evacuation, and thawing in liquid nitrogen in sequence;

[0018] The thawed glass container was sealed with a flame and then subjected to heating, cooling to room temperature, and liquid nitrogen immersion treatment in sequence.

[0019] The sealed glass container, which has been treated with liquid nitrogen immersion, is opened in a fume hood, and the solids inside are collected, ground, washed, and dried to obtain the pure donor-type covalent triazine organic framework material or the fluorinated donor-acceptor-type covalent triazine framework material.

[0020] In this invention, the pure donor-type covalent triazine organic framework material has high crystallinity and high nitrogen content, which is beneficial for the hybridization of the polymer framework's electron cloud. The fluorinated donor-acceptor type covalent triazine framework material has high crystallinity and high fluorine content, which reduces the polymer's band gap and is beneficial for improving the 2D in-plane electron and hole migration rates.

[0021] According to the present invention, preferably, the molar ratio of terephthalonitrile and trifluoromethanesulfonic acid is (1.5-2.5):1.

[0022] According to the present invention, preferably, the molar ratio of terephthalonitrile and 1,4-dicyanotetrafluorobenzene is (0.8-1.2):1, and more preferably 1:1.

[0023] According to the present invention, preferably, the heating treatment method includes: placing a sealed glass container in a muffle furnace and heating it from room temperature to 200-300°C at a rate of 4-6°C / min, and maintaining the temperature for 10-14 hours.

[0024] According to the present invention, preferably, the liquid nitrogen immersion treatment time is 8-12 minutes.

[0025] According to the present invention, preferably, the washing method includes: sequentially washing the ground solid with water, N,N-dimethylformamide and ethanol.

[0026] According to the present invention, preferably, the drying method comprises: drying the washed solid under vacuum at 80-120°C for 10-14 hours.

[0027] According to the present invention, preferably, in step S1: the step of preparing a covalent triazine organic framework nanosheet dispersion by electrochemical exfoliation includes:

[0028] (1) The covalent triazine organic framework material is pressed into a nickel foam sheet and the prepared sheet is placed on a tetrafluoroplatinum sheet electrode clamp as the cathode of the dual electrode system.

[0029] (2) Pt foil was selected as the anode of the dual-electrode system;

[0030] (3) The cathode and anode of the dual electrode system are placed in the electrolyte, and a DC voltage is applied to the dual electrode system to obtain the covalent triazine organic framework nanosheet dispersion.

[0031] According to the present invention, preferably, the amount of the covalent triazine organic framework material is 2-5 mg.

[0032] According to the present invention, preferably, the electrolyte is an N,N-dimethylformamide solution containing tetramethyltetrafluoroborate ammonium, wherein the concentration of the tetramethyltetrafluoroborate ammonium is 0.0002-0.5M, more preferably 0.1M.

[0033] According to the present invention, preferably, the intensity of the DC voltage is 10-25V, and the application time of the DC voltage is 1-6h.

[0034] According to the present invention, preferably, in step S2, the covalent triazine organic framework nanosheet dispersion is injected dropwise onto the surface of ultrapure water using a microsyringe.

[0035] According to the present invention, preferably, in step S3, the thickness of the chromium layer is 4.5-5.5 nm and the thickness of the gold layer is 50-70 nm.

[0036] According to the present invention, preferably, the organic field-effect transistor device comprises at least one of an organic semiconductor layer, a gate, a source, and a drain.

[0037] Another aspect of the present invention provides an organic field-effect transistor device prepared by the method described above.

[0038] The technical solution of the present invention has the following beneficial effects:

[0039] (1) The covalent triazine organic framework material of the present invention has high crystallinity, high chemical stability, and adjustable band gap, which is beneficial to improving electron migration rate and semiconductor performance, and is beneficial to broadening the application range of organic field-effect transistor devices prepared based on covalent triazine organic framework material.

[0040] (2) The covalent triazine organic framework material of the present invention is easy to obtain and the fabrication process of organic field-effect transistors is simple, providing a simple and low-cost method to meet the industrial requirements of nanodevice applications.

[0041] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0043] Figure 1 A schematic diagram of the molecular structure of the covalent triazine organic framework material provided in Example 1 of the present invention is shown.

[0044] Figure 2 The Fourier transform infrared spectrum of the covalent triazine organic framework material provided in Example 1 of this invention is shown. (wavenumber / cm) -1 (Wavenumber, transmittance / % is transmittance)

[0045] Figures 3(a) and (b) show scanning electron microscope images of the covalent triazine organic framework material provided in Example 1 of the present invention.

[0046] Figure 4The X-ray diffraction image of the covalent triazine organic framework material provided in Embodiment 1 of the present invention is shown. (degree refers to degree, intensity refers to intensity)

[0047] Figure 5 A schematic diagram of the experimental apparatus for the electrochemical stripping method provided in Embodiment 1 of the present invention is shown.

[0048] Figure 6 A photograph of the covalent triazine organic framework nanosheet dispersion provided in Example 1 of the present invention is shown.

[0049] Figures 7(a) and (b) show AFM atomic force microscopy characterization images of the covalent triazine organic framework nanosheets provided in Example 1 of the present invention.

[0050] Figures 8(a) and (b) show optical photographs of the covalent triazine organic framework nanosheets provided in Example 1 of the present invention.

[0051] Figure 9 A schematic diagram of the structure of an organic field-effect transistor device provided in Embodiment 1 of the present invention is shown.

[0052] Figure 10 The image shows the output characteristic curve of the organic field-effect transistor device prepared in Example 1 of the present invention, obtained from the test examples of the present invention, as a function of current and voltage. (Where: Ids(A) is the bias current, and Vds(V) is the bias voltage) Detailed Implementation

[0053] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0054] Example 1

[0055] This embodiment provides a method for fabricating an organic field-effect transistor device, which includes the following steps:

[0056] S1: Terephthalonitrile (2 mmol, 0.256 g) and trifluoromethanesulfonic acid (CF3SO3H, 1 mmol, 0.15 g) were placed into ampoules; the ampoules were subjected to freezing, evacuation, and thawing treatments in liquid nitrogen; the thawed ampoules were flame-sealed, and the sealed ampoules were placed in a muffle furnace, with the temperature gradually increased from room temperature to 250°C at a rate of 5°C / min, and held for 12 h; after completion, the ampoules were cooled to room temperature and immersed in liquid nitrogen for 10 min; the sealed ampoules after liquid nitrogen immersion treatment were opened in a fume hood, the solids were collected, ground into powder, and the powder was washed sequentially with water, N,N-dimethylformamide, and ethanol, and the washed powder was vacuum-dried at 100°C for 12 h to obtain the pure donor-type covalent triazine organic framework material (CTF-1), as shown. Figure 1-4 As shown.

[0057] S2: 2 mg of pure donor-type covalent triazine organic framework material (CTF-1) was pressed into a nickel foam tablet, and the prepared tablet was placed on a tetrafluoroplatinum electrode clip as the cathode of the dual-electrode system; Pt foil was selected as the anode of the dual-electrode system; the cathode and anode of the dual-electrode system were placed in the electrolyte, and a DC voltage was applied to the dual-electrode system to obtain a dispersion of covalent triazine organic framework nanosheets with a transverse size ≥10 μm. The dispersion was allowed to stand for 1 hour. Figure 5-8(b) As shown;

[0058] The electrolyte is an N,N-dimethylformamide solution containing 0.1M tetramethyltetrafluoroborate ammonium;

[0059] The intensity of the DC voltage is 20V, and the DC voltage is applied for 3 hours.

[0060] S3: Using a micro-syringe, the dispersion of covalent triazine organic framework nanosheets with a lateral size ≥10μm is injected dropwise onto the surface of ultrapure water. The SiO2 / Si substrate is passed through the interface between the covalent triazine organic framework nanosheets and ultrapure water to obtain a SiO2 / Si substrate containing triazine covalent organic framework nanosheets.

[0061] S4: Using a vacuum thermal evaporation coating machine (VNANO, model: VZZ-300), a chromium layer (5nm) and a gold layer (50nm) are sequentially deposited on the SiO2 / Si substrate containing triazine covalent organic framework nanosheets to obtain the organic field-effect transistor device.

[0062] The organic field-effect transistor device fabricated according to the method of this embodiment includes the following structure: Figure 9 The organic semiconductor layer, gate, source, and drain are shown.

[0063] Example 2

[0064] This embodiment provides a method for fabricating an organic field-effect transistor device. The only difference between this embodiment and Embodiment 1 is that terephthalonitrile (2 mmol) and 1,4-dicyanotetrafluorobenzene (2 mmol) are placed in an ampoule to prepare a fluorinated donor-acceptor type covalent triazine framework material, and then an organic field-effect transistor device is fabricated using the fluorinated donor-acceptor type covalent triazine framework material.

[0065] The organic field-effect transistor device fabricated according to the method of this embodiment includes the following structure: Figure 9 The organic semiconductor layer, gate, source, and drain are shown.

[0066] Test case

[0067] The electrical parameters of the organic field-effect transistor device prepared in Example 1, such as on / off ratio, turn-on current, turn-off current, and carrier mobility, were tested using the following methods:

[0068] (1) Place the constructed organic field-effect transistor device onto the chuck of the probe station, cover the vacuum chamber with the cover, use a mechanical pump to pump air for 30 minutes, and after the air pressure stabilizes at about 0.5 Pa, close the vacuum shut-off valve to keep the chamber in a low-pressure state.

[0069] (2) By adjusting the microscope of the matching imaging system, the microscopic image of the device can be displayed on the computer screen in real time;

[0070] (3) Move the probe to make good contact with the source and drain electrodes of the device through real-time microscopic images.

[0071] (4) Open the electrical test source meter and the corresponding control software on the computer, adjust the input voltage across the device, and obtain the output characteristic curve data image of current changing with voltage (e.g., Figure 10 As shown in the figure, the carrier mobility is 2.4 cm⁻¹. 2 / (V·s), switching ratio is 10 5 .

[0072] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method of fabricating an organic field effect transistor device, characterized by, The preparation method comprises the following steps: S1: a covalent triazine organic framework material is prepared into a covalent triazine organic framework nanosheet dispersion liquid by an electrochemical exfoliation method, and is left to stand; The preparation method of the covalent triazine organic framework material comprises: The terephthalonitrile and trifluoromethanesulfonic acid are put into a glass container; The glass container is subjected to freezing, air extraction and thawing treatment under liquid nitrogen in sequence; The glass container subjected to the thawing treatment is sealed by a flame, and is subjected to heating, cooling to room temperature and liquid nitrogen immersion treatment in sequence; The sealed glass container subjected to the liquid nitrogen immersion treatment is opened in a fume hood, and the solid therein is collected, ground, washed and dried to obtain a pure donor type covalent triazine organic framework material; The molar ratio of the terephthalonitrile to the trifluoromethanesulfonic acid is (1.5-2.5):1; The heating treatment method comprises: the sealed glass container is put into a muffle furnace for temperature rising, the temperature is raised at a gradient of 4-6 ℃ / min from room temperature to 200-300 ℃, and is kept for 10-14 h; The step of preparing the covalent triazine organic framework nanosheet dispersion liquid by the electrochemical exfoliation method comprises: (1) the covalent triazine organic framework material is pressed into a sheet with a foamed nickel, and the prepared sheet is placed on a four-fluorine platinum sheet electrode clamp as a cathode of a double electrode system; (2) a Pt foil is selected as an anode of the double electrode system; (3) the cathode and the anode of the double electrode system are put into an electrolyte, and a direct current voltage is applied to the double electrode system to obtain the covalent triazine organic framework nanosheet dispersion liquid; The amount of the covalent triazine organic framework material is 2-5 mg; The electrolyte is an N,N-dimethylformamide solution containing tetramethylammonium tetrafluoroborate, and the concentration of the tetramethylammonium tetrafluoroborate is 0.0002-0.5 M; The intensity of the direct current voltage is 20-25 V, and the application time of the direct current voltage is 3-6 h; The covalent triazine organic framework nanosheet is a covalent triazine organic framework nanosheet with a transverse size of ≥10 μm; S2: the covalent triazine organic framework nanosheet dispersion liquid is injected drop by drop onto the liquid surface of ultrapure water, and a SiO2 / Si substrate is passed through the interface between the covalent triazine organic framework nanosheet and the ultrapure water to obtain a SiO2 / Si substrate containing triazine covalent organic framework nanosheets; S3: a vacuum thermal evaporation film plating machine is used to evaporate and plate a chromium layer and a gold layer on the SiO2 / Si substrate containing triazine covalent organic framework nanosheets in sequence to obtain the organic field effect transistor device; The thickness of the chromium layer is 4.5-5.5 nm, and the thickness of the gold layer is 50-70 nm.

2. The method of producing an organic field effect transistor device according to claim 1, wherein, In step S1: The standing time is 0.5-1.5 h.

3. The method of producing an organic field effect transistor device according to claim 1, wherein, The liquid nitrogen immersion treatment time is 8-12 min; The washing method comprises: the solid subjected to the grinding is sequentially cleaned with water, N,N-dimethylformamide and ethanol; The drying method comprises: the solid subjected to the washing is vacuum dried at 80-120 ℃ for 10-14 h.

4. The method of producing an organic field effect transistor device according to claim 1, wherein, In step S2, the covalent triazine organic framework nanosheet dispersion liquid is injected drop by drop onto the liquid surface of ultrapure water by using a micro-sampler.

5. The method of producing an organic field effect transistor device according to claim 1, wherein The organic field effect transistor device is configured to include at least one of an organic semiconductor layer, a gate, a source, and a drain.

6. The organic field effect transistor device prepared by the method according to any one of claims 1-5.

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