Fullerene single crystal thin film and its manufacturing method and use

Abstract

The present invention relates to the technical field of organic semiconductors, and in particular to a fullerene single crystal thin film and its manufacturing method and use. A method for manufacturing a fullerene single crystal thin film at a gas-liquid-solid three-phase interface includes: Step 1: mixing fullerene with a solvent to form a mixed solution; and Step 2: crystallizing and growing the fullerene in the mixed solution on the surface of a substrate by a solution shearing method to obtain the fullerene single crystal thin film. The present invention directly controls the fullerene nucleation density at the three-phase line, thereby utilizing the continuous movement of the three-phase line to manufacture a large-area fullerene single crystal thin film, which has the advantages of uniform orientation, high uniformity, and high coverage, as well as excellent electron transport properties, meeting the needs of applications in the field of optoelectronics.

Description

[Technical Field]

[0001] The present invention relates to the technical field of organic semiconductors, and in particular to a fullerene single crystal thin film and its manufacturing method and use. [Background technology]

[0002] As star materials in the field of optoelectronics, fullerenes have a wide range of promising applications in many areas of organic electronics, such as solar cells, organic field-effect transistors, organic light-emitting diodes, and organic photodetectors. To date, all of these applications of fullerenes have been verified in the laboratory. However, fullerenes have yet to be industrially applied in the field of optoelectronics. This is primarily due to the current method of producing fullerene thin films, which typically involves vapor deposition. Vapor deposition requires high temperatures (>400°C), stringent high-vacuum conditions, and expensive equipment (ACS Nano 2013, 7, 10, 9122-9128). These factors result in high production costs and high energy consumption, making fullerene production unsuitable for industrial production. Furthermore, fullerene thin films obtained by vapor deposition have a high density of defect states in the fullerene crystal, which adversely affects their optoelectronic performance, such as electron mobility and exciton diffusion length.

[0003] Therefore, a low-cost solution-based method for producing fullerene crystals is needed. In fact, compared to other planar conjugated organic semiconductors, fullerenes' unique zero-dimensional structure makes the crystallization process more difficult to control. This is primarily due to the following two factors: First, the contact area between fullerene molecules is much smaller than that of planar molecules, resulting in a weaker driving force for crystallization. Second, the zero-dimensional nature of fullerene molecules makes them prone to rotation and lacks a preferred orientation. Conventional methods for producing fullerene crystals include liquid-liquid interfacial precipitation (Small 2018,14,11,e1703624.) and supramolecular gel crystallization (Adv.Sci.2022,9,2203662). Among these, the most common method is liquid-liquid interfacial precipitation, which utilizes slow mixing of solvents at the interface between a good solvent and a poor solvent for fullerenes, resulting in supersaturation of fullerenes at the interface, thereby facilitating crystal nucleation and growth. Although this method has attracted widespread attention and research, it has several major drawbacks, such as poor experimental reproducibility due to the uncontrollable crystal nucleation and growth process, and the chaotic size distribution of fullerene crystals. Furthermore, because the liquid-liquid interface deposition method is an ex-situ growth process, the crystals must undergo a complex transportation process before they can be used in optoelectronic applications, which inevitably causes damage to the crystals during the transportation process and makes it difficult to miniaturize and integrate devices.

[0004] As mentioned above, in situ fabrication of fullerene single-crystal thin films using solution processes is crucial for the practical application of fullerenes. Some scientists have attempted to overcome this challenge in recent years. For example, Li et al. (J. Am. Chem. Soc. 2012, 134, 2760-2765) obtained long fullerene single crystals measuring hundreds of microns using a droplet-fixed crystallization method. However, this method requires a fixed object to be placed at the center of the substrate to prevent the droplet from moving, making it difficult to continuously fabricate high-coverage fullerene single-crystal thin films. Similar methods, such as polydimethylsiloxane (PDMS)-assisted growth (Adv. Mater. 2015, 27, 4371-4376), also have similar problems. More importantly, while the fullerene crystals fabricated by these two methods exhibit a predetermined orientation, the distribution of this orientation is relatively disordered, and completely perpendicular orientations can sometimes appear between different crystals on the same substrate, significantly limiting the application of devices that integrate the fabricated fullerene single-crystal thin films. Zheng et al. (Carbon. 2018, 126, 299-304) fabricated millimeter-scale fullerene single-crystal thin films using dip coating. However, the resulting fullerene crystals had poor profiles (e.g., staggered profiles and uneven crystal thickness) and submicron thicknesses, which were unfavorable for carrier injection and vertical device fabrication. Furthermore, this method required the substrate to be removed from the solution, resulting in significant waste of raw materials. Jie et al. (Adv. Funct. Mater. 2021, 31, 2105459) fabricated inch-scale fullerene single-crystal nanowire arrays using solution-phase epitaxy. However, because this method required the use of a photoresist array as a growth-assisting layer, the resulting fullerene single-crystal arrays only covered approximately 9% of the substrate, and the removal of the photoresist array could damage the fullerene crystals.In addition to the disadvantages of discontinuous growth, irregular orientation, and low coverage, the uniformity of the resulting fullerene crystals is poor. Specifically, this is manifested by large differences in the height and width of the crystals, resulting in a large coefficient of variation in the performance of transistors manufactured based on fullerene crystals. For example, in 2021, Jie et al. (Adv. Funct. Mater. 2021, 31, 2105459) reported that the mobility coefficient of variation of a transistor manufactured based on a C60 fullerene single crystal array was as high as 42.9%, which is also disadvantageous for practical use.

[0005] In addition to the above issues, another difficulty in the current solution-based fabrication of fullerene single crystal thin films is controlling the crystal profile. Because fullerene molecules are spherical or ellipsoidal, large intermolecular spaces exist within fullerene crystals, allowing solvents to easily enter the fullerene crystals and form solvate crystals. This means that the solvent directly influences the structure of the fullerene crystals and significantly impacts their profile. For example, Park et al. (Chem. Commun. 2009, 32, 4803-4805) demonstrated that the solvent geometry influences the fullerene crystal profile, demonstrating that hexagonal crystals are obtained in quasi-three-dimensional solvents, such as carbon tetrachloride, while one-dimensional needle-like crystals are obtained in meta-substituted quasi-two-dimensional benzene-based solvents. Therefore, the selection and control of the solvent is crucial for the fabrication of fullerene single crystal thin films by solution methods. To obtain fullerene single crystal thin films with high coverage and good orientation, it would be highly advantageous to be able to control the fullerene crystal profile to be linear through the solvent process.

[0006] As mentioned above, to realize the practical application of fullerenes in the industrial field, the most ideal fullerene thin film is a large-area single-crystal thin film fabricated in situ by a solution process, which has high coverage, uniform orientation, high uniformity, and can be continuously produced. However, existing technologies are unable to fabricate such ideal fullerene single-crystal thin films, and there are three main challenges in this field: 1) the fullerene crystal growth process is complex, and overall control of the nucleation and growth processes is lacking; 2) existing in situ fullerene crystal thin film fabrication methods often require external environments, such as PDMS or photoresist arrays, to support the crystal growth, resulting in defects such as discontinuous growth, irregular orientation, low coverage, and poor uniformity; 3) the profile of fullerene crystals is highly dependent on the solvent selected, and it remains a mystery how to obtain fullerene single-crystal thin films with both good orientation and high coverage using a solvent process. Therefore, the in-situ fabrication of ideal large-area fullerene single crystal thin films by solution techniques remains a major technical challenge, and is also a prerequisite for the realization of the integration and industrialization of fullerene optoelectronic devices. Summary of the Invention

[0007] In view of the above-mentioned shortcomings of the existing techniques, an object of the present invention is to provide a fullerene single crystal thin film and a method for producing and using the same.

[0008] In a first aspect of the present invention, there is provided a method for producing a fullerene single crystal thin film at a gas-liquid-solid three-phase interface, the method comprising the steps of: Step 1: mixing fullerene with a solvent to form a mixture; Step 2: crystallizing and growing the fullerenes in the mixture on the surface of the substrate by a solution shearing method to obtain the fullerene single crystal thin film. In the step 1, the fullerene is one or more selected from C60, C70, C76, C78, C80 and C84.

[0009] Preferably, the fullerene is one or two selected from C60 and C70. In step 1, the solvent is one or more selected from o-xylene, 2-methylthiophene, 2-chlorothiophene, 2-chlorofuran, 3-methylthiophene, 2-ethylthiophene, m-xylene, m-difluorobenzene, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, tetrahydronaphthalene, 1-methylnaphthalene, carbon disulfide, 1,1,2,2-tetrachloroethane, carbon tetrachloride, 2-methoxythiophene, ethyl phenyl ether, 2-chloro-3-methylthiophene, and 2,5-dichlorothiophene.

[0010] In the step 1, the concentration of the fullerene is 0.2 to 20 mg / mL when calculated based on the total volume of the mixed solution. Preferably, it is 0.4 mg / mL to 10 mg / mL.

[0011] In the step 2, the material of the substrate is one or more selected from silicon, indium tin oxide, glass, quartz, sapphire, polyimide, and polyethylene terephthalate.

[0012] Preferably, a wetting layer is provided on the substrate. More preferably, the material of the wetting layer is one or more selected from benzocyclobutene, polyvinyl alcohol, cross-linked polymethyl methacrylate, cross-linked polystyrene, aluminum oxide, titanium oxide, zinc oxide, ethoxylated polyethyleneimine, phenyltrichlorosilane, gold, and aluminum.

[0013] In step 2, the solution shearing method involves placing a shearing tool above the substrate, so that the mixed solution is positioned between the shearing tool and the substrate, and the substrate or the shearing tool is moved at a predetermined linear velocity.

[0014] Preferably, the shearing tool is one or more selected from a stainless steel light bar, a stainless steel wire bar, a polytetrafluoroethylene bar, a blade and an application head. Preferably, the gap between the shearing tool and the substrate is 20 μm to 400 μm. More preferably, the distance between the shearing tool and the substrate is 50 μm to 200 μm. Preferably, the linear velocity in the solution shearing method is 1 μm / s to 1 mm / s. More preferably, the linear velocity in the solution shearing method is 5 μm / s to 200 μm / s.

[0015] In the above 2), the crystal growth temperature is 20°C to 120°C. Preferably, the crystal growth temperature is 25°C to 60°C.

[0016] In a second aspect of the present invention, a fullerene single crystal thin film obtained by the above-described manufacturing method is protected.

[0017] A third aspect of the present invention provides for the use of fullerene single crystal thin films as described above in the manufacture of optoelectronic devices.

[0018] In a fourth aspect of the present invention, an optoelectronic device including a fullerene single crystal thin film as described above is protected.

[0019] Preferably, the optoelectronic device is one or more selected from an organic field effect transistor, an organic solar cell, an organic complementary inverter, an organic electrical circuit, an organic light emitting diode, an organic memory device, an organic photodetector and an organic thermoelectric device.

[0020] Compared with existing technologies, the present invention has the following beneficial effects: In the present invention, the nucleation density of fullerenes at the three-phase line is directly controlled, and the continuous movement of the three-phase line is utilized to produce a large-area fullerene single crystal thin film. In addition, the solvent is controlled to adjust the profile of the fullerene crystals, thereby obtaining a large-area fullerene single crystal thin film with uniform orientation, high uniformity, and high coverage, and this large-area fullerene single crystal thin film has the highest coverage currently available (even over 95%).

[0021] The use of high-quality fullerene single crystal thin films of the present invention can realize the practical application of fullerenes in many fields of organic electronics. Here, the variation coefficients of mobility and threshold voltage of organic field-effect transistor (OFET) arrays based on C60 fullerene single crystal thin films are both less than 15%, which are the most uniform performance values among OFETs currently manufactured based on C60 fullerene single crystal thin films. The organic field-effect transistor based on C70 fullerene single crystal thin films has a thickness of 0.195 cm 2 V -1 s -1 This is the highest mobility among OFETs currently fabricated based on C70 fullerene single crystal thin films. Other applications, such as organic solar cells and organic complementary inverters, also show excellent performance. [Brief explanation of the drawings]

[0022] [Figure 1] 1 shows optical microscope images of the entire and locally enlarged C60 fullerene single crystal thin film produced in Example 1 of the present application. [Figure 2] 1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 2 of the present application. [Figure 3] 1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 3 of the present application. [Figure 4] 1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 4 of the present application. [Figure 5]1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 5 of the present application. [Figure 6] 1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 6 of the present application. [Figure 7] 1 shows an optical microscope photograph of a C60 fullerene single crystal thin film produced in Example 7 of the present application. [Figure 8] 1 shows optical microscope images of the entire and locally enlarged C70 fullerene single crystal thin film produced in Example 8 of the present application. [Figure 9] 1 shows an optical microscope photograph of a C70 fullerene single crystal thin film produced in Example 9 of the present application. [Figure 10] In Example 10 of the present application, the characterization of the field-effect transistor array fabricated with the C60 fullerene single crystal thin film is shown, where (a) and (b) are the transfer characteristic curves and typical output characteristic curves of 70 devices, respectively, where the illustration in (a) is a schematic diagram of the structure of the field-effect transistor, and (c) and (d) are statistical graphs of the mobility and threshold voltage of 70 devices, respectively. [Figure 11] 11 shows typical transfer characteristic curves and output characteristic curves of a field effect transistor fabricated using a C70 fullerene single crystal thin film in Example 11 of the present application. [Figure 12] 12 shows the structure of an organic solar cell fabricated based on a C60 fullerene single crystal thin film and its JV curve, where (a) is the structure diagram and (b) is the JV curve. [Figure 13] The optical microscope image and performance curves of the organic complementary inverter fabricated based on the C60 fullerene single crystal thin film in Example 13 of the present application are shown, where (a) is the optical microscope image, (b) is the voltage transfer curve, (c) is the voltage gain curve, and (d) is the schematic diagram of the electrical circuit of the organic complementary inverter. [Figure 14] 1 shows an optical microscope photograph of a thin film produced in Comparative Example 1 of the present application. [Figure 15] 1 shows an optical microscope photograph of a thin film produced in Comparative Example 2 of the present application. [Figure 16] 1 shows an optical microscope photograph of a thin film produced in Comparative Example 3 of the present application. [Figure 17] 1 shows an optical microscope photograph of a thin film produced in Comparative Example 4 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0023] The inventors have found that fullerene thin films produced by existing technologies have drawbacks such as low crystallinity, small area, irregular orientation, low coverage, and poor uniformity, and after extensive research, have discovered that fullerenes can be crystallized and grown on the surface of a substrate using a solution shearing method. By controlling the behavior of crystal nucleation in the solvent process and the air-solution-substrate three-phase line, they have succeeded in producing high-quality, large-area fullerene single crystal thin films with high coverage, uniform orientation, high crystallinity, and good uniformity. The fullerene single crystal thin films of the present invention meet the needs for the application of fullerene materials in the field of optoelectronics and can be used in fields such as organic field-effect transistors, organic solar cells, and organic electrical circuits.

[0024] The present invention uses the following technical solutions: In a first aspect of the present invention, there is provided a method for producing a fullerene single crystal thin film at a gas-liquid-solid three-phase interface, the method comprising the steps of: Step 1: mixing fullerene with a solvent to form a mixture; Step 2: crystallizing and growing the fullerenes in the mixture on the surface of the substrate by a solution shearing method to obtain the fullerene single crystal thin film.

[0025] The method of the present application does not require the use of a separate fixture or photoresist array to assist crystallization, and promotes the nucleation of crystals and the continuous movement of the three-phase line by controlling the evaporation of the solvent at the air-solution-substrate three-phase line, thereby promoting the continuous growth of oriented fullerene crystals, thereby enabling the production of large-area fullerene single crystal thin films with high coverage and that can be produced on a large scale.

[0026] In the method according to the present invention, in step 1, the fullerene is one or more selected from C60, C70, C76, C78, C80 and C84, preferably C60 or C70.

[0027] In the method of the present invention, the solvent selected in step 1 is one or more selected from o-xylene, 2-methylthiophene, 2-chlorothiophene, 2-chlorofuran, 3-methylthiophene, 2-ethylthiophene, m-xylene, m-difluorobenzene, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, tetrahydronaphthalene, 1-methylnaphthalene, carbon disulfide, 1,1,2,2-tetrachloroethane, carbon tetrachloride, 2-methoxythiophene, ethyl phenyl ether, 2-chloro-3-methylthiophene, and 2,5-dichlorothiophene. The solvent may be a single solvent, for example, 2-chlorothiophene, 2-chloro-3-methylthiophene, 2-methoxythiophene, 3-methylthiophene, 2-ethylthiophene, and o-xylene. Because fullerene crystals tend to bond with solvent molecules to form solvate crystals, fullerene crystals often exhibit different profiles in different solvents. For example, C60 fullerene typically forms needle-shaped crystals in m-xylene, but typically forms hexagonal crystals in carbon tetrachloride. To achieve as high a coverage as possible on the substrate with a fullerene single crystal thin film, the present invention selects a solvent that produces stripe-shaped crystals with both good orientation and high coverage. If the crystal exhibits a different profile in a single solvent, a second solvent can be added to adjust the crystal profile. For example, C60 fullerene crystals exhibit non-oriented, discontinuous, and hexagonal crystals with low coverage in carbon tetrachloride. By adding a solvent that produces needle-shaped crystals, such as m-xylene, 3-methylthiophene, or toluene, the characteristics of the two profiles can be combined to form stripe-shaped crystals with good orientation and high coverage. The use of two solvents can increase the coverage of the fullerene single crystal thin film by at least eight times. For example, the solvent may be a mixture of two or more solvents, such as 3-methylthiophene and carbon tetrachloride, 2-chlorothiophene and m-xylene, or 2-chlorothiophene and 2-methylthiophene.Furthermore, for example, when the solvent is a mixture of 3-methylthiophene and carbon tetrachloride, the volume ratio of 3-methylthiophene to carbon tetrachloride is 1:(1-5), or may be 1:(1-2.5), 1:(2-4.2), or 1:(3.6-5), specifically 1:3. When the solvent is a mixture of 2-chlorothiophene and m-xylene, the volume ratio of 2-chlorothiophene to m-xylene is (1-6):1, or may be (1-3):1, (1.5-4.6):1, (3.6-5.8):1, or (4.2-6):1, specifically 4:1. When the solvent is a mixture of 2-chlorothiophene and m-xylene, the volume ratio of 2-chlorothiophene to m-xylene is (1 to 15):1, but may also be (1 to 4.2):1, (3.4 to 5.6):1, (4.8 to 10.3):1, or (8.6 to 15):1, and specifically may be 9:1.

[0028] In the method according to the present invention, in step 1, the concentration of the fullerene, calculated based on the total volume of the mixture, is 0.2 to 20 mg / mL, and may be, for example, 0.4 mg / mL to 2.2 mg / mL, 2.8 mg / mL to 3.2 mg / mL, 2.9 mg / mL to 4.6 mg / mL, 3.6 mg / mL to 6.1 mg / mL, 5.7 mg / mL to 7.2 mg / mL, 6.9 mg / mL to 9.2 mg / mL, 8.3 mg / mL to 10 mg / mL, or 0.4 mg / mL to 10 mg / mL. In a specific embodiment, the concentration is 0.45 mg / mL, 3 mg / mL, 6 mg / mL, 7.5 mg / mL, 9 mg / mL, or 10 mg / mL.

[0029] In the method of the present invention, in step 2, the substrate is made of one or more materials selected from silicon, indium tin oxide, glass, quartz, sapphire, polyimide, and polyethylene terephthalate. Preferably, the substrate is made of silicon or indium tin oxide (ITO). For example, the substrate is a silicon wafer heavily doped with phosphorus or boron. In a specific embodiment, the substrate is a silicon wafer heavily doped with phosphorus, which includes a 285 nm thick silica layer on its surface.

[0030] In the method according to the present invention, a wetting layer is provided on the substrate in step 2. Preferably, the material of the wetting layer is selected from the group consisting of benzocyclobutene (BCB), polyvinyl alcohol (PVA), cross-linked polymethyl methacrylate (c-PMMA), cross-linked polystyrene (c-PS), aluminum oxide (Al2O3), titanium oxide (TiO2), zinc oxide (ZnO), ethoxylated polyethyleneimine (PEIE), phenyltrichlorosilane (PTS), gold (Au), and aluminum (Al). The wetting layer can be fabricated by spin coating (polymers), vapor deposition (metals), sol-gel (metal oxides), or gas phase deposition (self-assembled monolayers). For example, if the material is a polymer, such as PVA, c-PMMA, or c-PS, spin coating is used; if the material is a metal, such as Au or Al, vapor deposition is used; if the material is a metal oxide, such as Al2O3, TiO2, or ZnO, sol-gel deposition is used; and if the material is a self-assembled monolayer, such as PTS, gas phase deposition is used. In a specific embodiment, the wetting layer is fabricated by BCB, c-PMMA, Au, PEIE, or PTS.

[0031] In the method of the present invention, in step 2, the solution shearing method involves placing a shearing tool above the substrate, positioning the mixed solution between the shearing tool and the substrate, and allowing the substrate or the shearing tool to operate at a predetermined linear velocity. Preferably, the substrate operates at a predetermined linear velocity, and after operation, a large-area fullerene single crystal thin film with high coverage is obtained on the substrate. Preferably, the shearing tool is one or more selected from a stainless steel light bar, a stainless steel wire bar, a polytetrafluoroethylene bar, a blade, and a coating head. In a specific embodiment, it is a stainless steel light bar. Preferably, the distance between the shearing tool and the substrate is 20 μm to 400 μm, for example, 50 μm to 150 μm, 100 μm to 250 μm, 200 μm to 350 μm, 300 μm to 400 μm, 50 μm to 200 μm, or 100 μm. Preferably, the linear velocity in the solution shearing method is 1 μm / s to 1 mm / s, for example, 5 μm / s to 105 μm / s, 58 μm / s to 155 μm / s, 126 μm / s to 205 μm / s, 189 μm / s to 450 μm / s, 350 μm / s to 600 μm / s, 550 μm / s to 780 μm / s, 700 μm / s to 950 μm / s, 820 μm / s to 1 mm / s, 8 μm / s, 10 μm / s, 12 μm / s, 15 μm / s, or 20 μm / s.

[0032] In the method of the present invention, in step 2, the crystal growth temperature is 20°C to 120°C, and may be, for example, 20°C to 45°C, 36°C to 58°C, 47°C to 78°C, 62°C to 96°C, 84°C to 105°C, 96°C to 120°C, or 25°C to 60°C. In a specific embodiment, the temperature is 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or 60°C. Due to the difficulty of growing fullerene crystals, it is necessary to precisely control the crystal nucleation and growth process by adjusting growth conditions such as substrate temperature, shear rate, and solution concentration. For example, if the temperature is too high, the solvent will be released too quickly, resulting in a high nucleation density at the gas-liquid-solid three-phase line and insufficient solute for growth in either direction of the crystal nuclei, resulting in disordered orientation of the fullerene crystals and poor profile, such as increased roughness. In this case, increasing the linear velocity and decreasing the concentration of the mixed solution can be effective. On the other hand, if the temperature is too low, the solvent will be released too slowly, making it difficult to form nuclei at the three-phase line, and only irregular amorphous phases can be formed. In this case, the linear velocity can be reduced to increase the concentration of the mixture.

[0033] In a second aspect of the present invention, a fullerene single crystal thin film obtained by the above-described manufacturing method is protected. The fullerene single crystal thin film of the present invention can have a substrate coverage rate of 90% or more. The coverage rate can be obtained by observing the fullerene single crystal thin film with an optical microscope and analyzing it with ImageJ software.

[0034] A third aspect of the present invention provides for the use of fullerene single crystal thin films as described above in the manufacture of optoelectronic devices.

[0035] In a fourth aspect of the present invention, an optoelectronic device including a fullerene single crystal thin film as described above is protected.

[0036] In the optoelectronic device according to the present invention, the optoelectronic device is one or more selected from an organic field effect transistor, an organic solar cell, an organic complementary inverter, an organic electric circuit, an organic light emitting diode, an organic memory device, an organic photodetector, and an organic thermoelectric device.

[0037] When the optoelectronic device is an organic field effect transistor, the method for manufacturing the organic field effect transistor is as follows: 1) Source and drain electrodes are formed on the fullerene single crystal thin film as described above to obtain the organic field effect transistor.

[0038] The source and drain electrodes are the collective term for the source electrode (S) and the drain electrode (D). The voltage and current between the source and drain electrodes are V DS , I DS When a voltage is applied to the gate electrode (G), the electric field affects the current between the source electrode and the drain electrode through the gate dielectric layer. Preferably, the source / drain electrodes are manufactured by one or more methods selected from the group consisting of a vapor deposition method, a transfer method, and a printing method.

[0039] Preferably, the source and drain electrodes are one or more selected from silver, lithium fluoride / aluminum, gold, graphene, calcium, and magnesium.

[0040] When the optoelectronic device is an organic solar cell, the method for manufacturing the organic solar cell is as follows: Step 1: Producing a donor material layer on the fullerene single crystal thin film as described above to obtain a bilayer structure film; Step 2: forming an upper electrode on the bilayer structure film to obtain the organic solar cell.

[0041] Preferably, the donor material layer is made of a material selected from a donor small molecule and a donor polymer. More preferably, the donor small molecule is selected from 2-((7-(4-(di-p-tolylamino)phenyl)benzo[C][1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCPB), and the donor polymer is selected from poly(3-hexylthiophene-2,5-diyl) (P3HT).

[0042] Preferably, in step 1, the method for manufacturing the donor material layer is one or two selected from spin coating and vapor deposition. Preferably, in step 2, the upper electrode is selected from gold, molybdenum trioxide / silver, platinum, titanium, chromium, and the like. Preferably, in step 2, the method for manufacturing the upper electrode is one or more selected from the group consisting of a vapor deposition method, a transfer method, and a printing method.

[0043] When the optoelectronic device is an organic complementary inverter, the method for manufacturing the organic complementary inverter is as follows: Step 1: growing a p-type semiconductor thin film on the other side of the fullerene single crystal thin film substrate as described above; Step 2: depositing electrodes on the substrate including the fullerene single crystal thin film and the p-type semiconductor thin film to obtain the organic complementary inverter.

[0044] Preferably, in step 1, the method for growing the p-type semiconductor thin film is one or more selected from the group consisting of a solution shear method, a droplet fixed crystallization method, an evaporation method, and a physical vapor transport method.

[0045] Preferably, in step 1, the material of the p-type semiconductor thin film is one or more selected from the group consisting of fused heterocycle and benzoheterocycle derivatives, acene compounds and their derivatives, oligothiophene derivatives, and porphyrin derivatives.

[0046] Preferably, in step 2, the electrode is one or more selected from silver and gold. The fullerene single crystal thin film obtained by the method of the present invention has the advantages of a coverage rate of more than 95%, a large area, high uniformity, and uniform orientation. The organic field-effect transistor array obtained with the C60 fullerene single crystal thin film of the present invention has good electron transport performance, and the highest electron mobility of the organic field-effect transistor array is 1 cm. 2 V -1 s -1 The coefficient of variation of electron mobility was only 13.3%, which is much lower than the 42.9% reported in the existing literature. The organic field-effect transistor array obtained with the C70 single-crystal thin film had a size of 0.195 cm 2 V -1 s -1 This is the first time that an electron mobility of 0.0132 cm has been achieved, exceeding the previous literature report of 0.0132 cm. 2 V -1 s -1 This is much higher than the conventional method. The organic solar cell obtained with the C60 fullerene single crystal thin film of the present invention exhibits good photovoltaic effect, with a photoelectric conversion efficiency of 0.123%. The organic complementary inverter obtained with the fullerene single crystal thin film described in the present invention has almost no voltage loss and a high voltage gain. In summary, the fullerene single crystal thin film obtained by the method of the present invention has potential for practical use in the fields of optoelectronics and complementary electrical circuit integration.

[0047] Although the present invention will be described below with reference to specific examples, those skilled in the art will readily appreciate other advantages and benefits of the present invention from the disclosure herein. The present invention may be implemented or applied in other different specific embodiments, and the details herein may be modified or changed in various ways based on different perspectives and applications without departing from the spirit of the present invention.

[0048] Before describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the following specific embodiments. It should also be understood that the terms used in the examples of the present invention are intended to describe specific embodiments, and do not limit the scope of protection of the present invention. In the present specification and claims, the singular forms "one," "one," and "this" include the plural forms unless otherwise clearly indicated.

[0049] When a range of values is given in the examples, it should be understood that the endpoints of each range and any value between the endpoints can be selected unless otherwise specified in the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. Apart from the specific methods, equipment, and materials used in the examples, a person skilled in the art can realize the present invention using any method, equipment, and material in the existing art that is similar or equivalent to the method, equipment, and material described in the examples of the present invention, based on their understanding of the existing technology and the description of the present invention.

[0050] Examples 1 to 9 In Examples 1 to 9, large-area fullerene single crystal thin films were produced with reference to the materials and parameters in Table 1, and the production method included the following steps. 1) Silicon wafers, quartz wafers, or ITO substrates were used. After modifying the substrate with a wetting layer, the substrate containing the wetting layer was heated on a heating table. If the wetting layer was made of a polymer, such as BCB, c-PMMA, or PEIE, spin coating was used; if the wetting layer was made of Au, evaporation was used; and if the wetting layer was made of PTS, a vapor deposition method was used. Here, the silicon wafer was a heavily doped P-type silicon wafer with a 285 nm thick silica layer on its surface. 2) The mixture of fullerene and solvent was thoroughly and uniformly mixed using ultrasound, and the mixture was then injected into the gap between the stainless steel light bar and the substrate via the stainless steel light bar located approximately 100 μm above the surface of the substrate. Once the mixture had stabilized, the heating table was moved at a predetermined linear velocity. After the operation was completed, a large-area fullerene single crystal thin film was obtained on the substrate.

[0051] The fullerene single crystal thin films obtained in Examples 1 to 9 were characterized in profile by an optical microscope, and the results are shown in FIGS.

[0052] From Figure 1(a), it can be seen that a large-area fullerene single crystal thin film was obtained by the method of the present application. From Figure 1(b), it can be seen that in the C60 fullerene single crystal thin film obtained in Example 1, the crystals had similar orientation and similar color, and there were no obvious profile defects in the crystals, such as cracks, cavities, or branched profiles, indicating that the method of the present application can produce a high-quality fullerene single crystal thin film with uniform orientation and height. Furthermore, the coverage of the single crystal thin film was analyzed using ImageJ software, and from Figure 1(b), it can be seen that the crystal coverage was high at 84%.

[0053] 2 to 9, it can be seen that the C60 fullerene and C70 fullerene single crystal thin films obtained by the method of the present application have similar orientations and colors between the individual crystals, and the maximum coverage can exceed 95%, i.e., a fullerene single crystal thin film with uniform orientation, uniform height, and high coverage can be obtained.

[0054] Table 1 shows the specific values of the coverage of the fullerene single crystal thin film in Examples 1 to 9. [Table 1] TIFF2025525384000003.tif65170

[0055] Example 10 In Example 10, an organic field effect transistor array was fabricated using the C60 fullerene single crystal thin film obtained in Example 1, which included the following steps: Source and drain electrodes were deposited on the C60 fullerene single crystal thin film prepared in Example 1. That is, a mask was fixed on the C60 fullerene single crystal thin film, and 1 nm LiF and 80 nm Al were sequentially deposited as source and drain electrodes. At the same time, the heavily doped silicon substrate and silica / BCB were used as the gate electrode and gate insulating layer, respectively, to obtain an organic field-effect transistor array.

[0056] In this example, 70 organic field effect transistors were obtained. The N-type transfer characteristic curves (gate electrode voltage V) of 70 organic field-effect transistors were measured using a semiconductor parameter analyzer in a glove box. G : -10 to 40 V, source / drain voltage V DS :40V) and output characteristic curve (gate electrode voltage V G : 0~40V, step interval: 8V; source / drain voltage V DS The electron mobility (μ) and threshold voltage (V T ) were extracted and the mean value and coefficient of variation σ (coefficient of variation = standard deviation / mean value × 100%) were calculated. The results are shown in Figure 10. The performance of an organic field-effect transistor is mainly determined by performance parameters such as mobility and threshold voltage. Among these, mobility is the parameter that plays a crucial role in the performance of an organic field-effect transistor. It is the rate at which carriers move at a unit electric field strength. Generally, the higher the mobility, the better the performance of the organic field-effect transistor. The threshold voltage is the minimum gate electrode voltage required to open the transistor. The lower the absolute value of the threshold voltage, the better.

[0057] From Figure 10, it can be seen that all 70 organic field-effect transistors achieved good operation, and their transport characteristic curves (Figure 10a) had good overlap. The C60 single crystal thin film of the present invention had good electron transport performance, with the highest electron mobility of 1 cm. 2 V -1 s -1 exceeding 100%, satisfying the needs of most organic electronic circuits, sensor applications, and flexible displays. The coefficients of variation for electron mobility and threshold voltage were 13.3% (Figure 10c) and 11.4% (Figure 10d), respectively, indicating that the fullerene single crystal thin film produced by this invention has fairly good uniformity. This coefficient of variation is much lower than that of the transistors produced by Jie et al. in 2021 using C60 single crystal arrays, and the coefficient of variation for electron mobility was as high as 42.9% (Adv.Funct.Mater.2021,31,2105459).

[0058] Example 11 In Example 11, an organic field effect transistor was fabricated based on the C70 fullerene single crystal thin film of Example 8, including: The basic flow is the same as in Example 10, except that the evaporated source and drain electrodes are made of Ag.

[0059] The N-type transfer characteristic curve (V G :-10~50V;V DS :50V) and output characteristic curve (V G : 0~50V, step interval: 10V;V DS The results are shown in FIG.

[0060] On-off ratio (I on / I off ) is an important performance index of organic field-effect transistors, and represents the ratio of the current in the on-state to the off-state of the organic field-effect transistor. The higher the on-off ratio, the better the performance of the organic field-effect transistor.

[0061] From Figure 11, the electron mobility of the organic field-effect transistor fabricated based on the C70 fullerene single crystal thin film was 0.195 cm 2 V -1 s -1 This is the highest value for an OFET based on a C70 fullerene single crystal to date. The highest electron mobility for a C70 fullerene single crystal using existing technology is 0.0132 cm 2 V -1 s -1 (Chemical Physics Letters.2022,807,140094).

[0062] Example 12 In this Example 12, an organic solar cell was fabricated based on the C60 fullerene single crystal thin film of Example 7, including: 1) A two-layer structure film made of DTDCPB with a thickness of 60 nm was prepared on the C60 fullerene single crystal thin film of Example 7 by vapor deposition. 2) Molybdenum trioxide (10 nm thick) and silver (80 nm thick) were evaporated onto the bilayer structure film as the top electrode to obtain an organic solar cell. 3) The organic solar cell obtained in step 2) was irradiated with light using a solar simulator in a glove box, and a current density-voltage (JV) curve was obtained using a semiconductor parameter analyzer. Based on the JV curve, the open circuit voltage (Voc), short circuit voltage (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) were obtained, and the results are shown in Figure 12.

[0063] The open circuit voltage (Voc) is the voltage generated when irradiated with light when there is no current circuit (positive and negative electrodes are disconnected), i.e., the maximum output voltage of the solar cell, and is expressed in V. The short circuit current (Jsc) is the current generated when the device is irradiated with light and forms a circuit (positive and negative electrodes are short-circuited) when the applied electric field is zero, i.e., the maximum output current of the solar cell, and is expressed in A / cm. 2 or mA / cm 2The fill factor (FF) is the ratio of the product of the current and voltage at maximum output to the product of the short-circuit current and open-circuit voltage. The power conversion efficiency (PCE) is the efficiency with which a solar cell converts solar energy into electrical energy.

[0064] From FIG. 12, it can be seen that the organic solar cell manufactured based on the high coverage fullerene single crystal thin film of the present application exhibits good photovoltaic effect, with a photoelectric conversion efficiency reaching 0.123%, demonstrating that the fullerene single crystal thin film has potential for practical use in the field of optoelectronics.

[0065] Example 13 In this Example 13, an organic complementary inverter was fabricated based on the C60 fullerene single crystal thin film of Example 1. 1) A single crystal thin film of 1,4,8,11-tetramethyl-6,13-(triethylmethylsilylethynyl)pentacene (TMTES-PEN) was grown on the other side of the substrate containing the C60 fullerene single crystal thin film of Example 1. The growth method was a solution shear method similar to that used to produce the fullerene single crystal thin film of Example 1, with the only differences being that the concentration of the mixed solution consisting of the solvent and TMTES-PEN, the substrate temperature, and the shear rate were m-xylene, 8 mg / mL, 40°C, and 50 μm / s, respectively. 2) A silver electrode having a thickness of 80 nm was vapor-deposited on the substrate containing the fullerene single crystal thin film and the TMTES-PEN single crystal thin film of step 1). 3) The voltage transfer curve and voltage gain curve of the organic complementary inverter were measured using a semiconductor analyzer in a glove box.

[0066] The voltage conversion curve is the output voltage (V out ) input voltage (V in ) is a curve of change according to the change of voltage, and the definition of voltage gain is given by the formula dV out / dV in It is displayed as:

[0067] From Figure 13, it can be seen that the voltage reversal occurs at the point on the voltage transfer curve (Figure 13b) that is the same as the ideal power supply voltage (V DD) (about 20V), there is almost no voltage loss, and the V DD It can be seen that the voltage gain reaches 63.5 when V = 40 V (Fig. 13c). The good voltage reversal characteristics indicate that the fullerene single crystal thin film of the present invention has potential for application in complementary integrated circuits.

[0068] Comparative Example 1 The difference between this Comparative Example 1 and Example 1 is that the growth temperature was lowered by 10°C, i.e., the growth temperature was 25°C. All other conditions were the same as those of Example 1, and the specific materials and parameters are shown in Table 1.

[0069] The thin film obtained in Comparative Example 1 was profile characterized by optical microscopy, and the results are shown in FIG.

[0070] From FIG. 14, it can be seen that the low growth temperature caused the solvent to evaporate too slowly at the three-phase line, resulting in an insufficient nucleation density of C60 fullerenes and no C60 fullerene crystals being generated.

[0071] Comparative Example 2 The difference between this Comparative Example 2 and Example 1 is that the growth temperature was increased by 10°C, i.e., the growth temperature was 45°C. All other conditions were the same as in Example 1, and the specific materials and parameters are shown in Table 1.

[0072] The thin film obtained in Comparative Example 2 was profile characterized by optical microscopy, and the results are shown in FIG. From Figure 15, we can see that the high growth temperature caused the solvent to evaporate too quickly, resulting in a high nucleation density at the three-phase line and sufficient solute for the growth of crystal nuclei, ultimately resulting in the formation of C60 fullerene crystals with disordered orientation and an uneven profile.

[0073] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that only carbon tetrachloride was used as the solvent. All other aspects were the same as in Example 2, and specific materials and parameters are shown in Table 1.

[0074] The thin film obtained in Comparative Example 3 was profile characterized by optical microscopy, and the results are shown in FIG.

[0075] Figure 16 shows that when carbon tetrachloride alone was used as the solvent, only small, discontinuous polygonal crystals were obtained, which is consistent with literature reports (Chem. Commun. 2009, 4803-4805). On the other hand, when a mixed solvent of carbon tetrachloride and 3-methylthiophene was used, striped crystals were obtained that combined the properties of hexagonal and one-dimensional crystals, resulting in high coverage and good orientation (Figure 2), with a coverage rate that was improved by more than eight times. These results demonstrate that the profile of fullerene crystals can be significantly improved by selecting the right solvent during the production process, facilitating their practical use in many fields.

[0076] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that only m-xylene was used as the solvent; otherwise, all other aspects were the same as in Example 3. Specific materials and parameters are shown in Table 1. The thin film obtained in Comparative Example 4 was profile characterized by optical microscopy, and the results are shown in FIG.

[0077] Figure 17 shows that when m-xylene alone was used as the solvent, only one-dimensional crystals with low coverage, disordered orientation, and overlapping layers were obtained. On the other hand, when a mixed solvent of m-xylene and 2-chlorothiophene was used, striped crystals with high coverage and uniform orientation were obtained (Figure 3), with a coverage rate improved by approximately 5.3 times. These results demonstrate the importance of adjusting the solvent in the process of manufacturing fullerene crystal thin films.

[0078] The above examples are intended to illustrate the embodiments disclosed in the present invention and are not to be construed as limiting the present invention. Furthermore, various modifications and variations of the methods and compositions of the inventions described herein will be readily apparent to those skilled in the art without departing from the scope and spirit of the present invention. While the present invention has been specifically described in conjunction with many specific preferred embodiments of the present invention, it should be understood that the present invention is not limited to these specific examples. Indeed, any inventions resulting from various modifications readily apparent to those skilled in the art, as described above, are within the scope of the present invention.

Claims

1. A method for producing a fullerene single crystal thin film at a gas-liquid-solid three-phase interface, comprising: Step 1: mixing fullerene with a solvent to form a mixed solution; a step 2 of crystallizing and growing the fullerenes in the mixture on the surface of the substrate by a solution shearing method to obtain the fullerene single crystal thin film; A method comprising:

2. Technical feature A1: the fullerene is one or more selected from C60, C70, C76, C78, C80 and C84; Technical feature A2, wherein the solvent is one or more selected from o-xylene, 2-methylthiophene, 2-chlorothiophene, 2-chlorofuran, 3-methylthiophene, 2-ethylthiophene, m-xylene, m-difluorobenzene, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, tetrahydronaphthalene, 1-methylnaphthalene, carbon disulfide, 1,1,2,2-tetrachloroethane, carbon tetrachloride, 2-methoxythiophene, ethyl phenyl ether, 2-chloro-3-methylthiophene, and 2,5-dichlorothiophene; Technical feature A3: when calculated based on the total volume of the mixed solution, the concentration of the fullerene is 0.2 mg / mL to 20 mg / mL, preferably 0.4 mg / mL to 10 mg / mL; Technical feature A4: the material of the substrate is one or more selected from silicon, indium tin oxide, glass, quartz, sapphire, polyimide, and polyethylene terephthalate; Technical Feature A5: the crystal growth temperature is 20°C to 120°C, preferably 25°C to 60°C; 2. The method of claim 1, comprising at least one of:

3. 3. The method of claim 2, wherein the substrate is provided with a wetting layer thereon.

4. 4. The method of claim 3, wherein the material of the wetting layer is one or more selected from the group consisting of benzocyclobutene, polyvinyl alcohol, cross-linked polymethyl methacrylate, cross-linked polystyrene, aluminum oxide, titanium oxide, zinc oxide, ethoxylated polyethyleneimine, phenyltrichlorosilane, gold, and aluminum.

5. 2. The method of claim 1, wherein in step 2, the solution shearing method comprises providing a shearing tool above the substrate, the mixed solution being positioned between the shearing tool and the substrate, and the substrate or the shearing tool moving at a predetermined linear velocity.

6. the shearing tool is one or more selected from a stainless steel light bar, a stainless steel wire bar, a polytetrafluoroethylene bar, a blade, and an application head; and / or the separation distance between the shearing tool and the substrate is between 20 μm and 400 μm, preferably between 50 μm and 200 μm; and / or the linear velocity in the solution shearing method is 1 μm / s to 1 mm / s, preferably 5 μm / s to 200 μm / s.

7. A fullerene single crystal thin film obtained by the manufacturing method according to any one of claims 1 to 6.

8. Use of the fullerene single crystal thin film according to claim 7 in an optoelectronic device.

9. An optoelectronic device comprising the fullerene single crystal thin film according to claim 7.

10. 10. The optoelectronic device of claim 9, wherein the optoelectronic device is one or more selected from the group consisting of an organic field effect transistor, an organic solar cell, an organic complementary inverter, an organic electrical circuit, an organic light emitting diode, an organic memory device, an organic photodetector, and an organic thermoelectric device.

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