Method for p-type doping of semiconducting layer of organic field effect transistor and prepared organic field effect transistor

Abstract

The application discloses a method for P-type doping of an organic field effect transistor semiconductor layer and an organic field effect transistor prepared by the method. 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4-TCNQ) is dissolved in an orthogonal solvent of the organic semiconductor layer as a P-type dopant, and the P-type dopant is spin-coated on an organic semiconductor layer film which has been spin-coated in an air atmosphere, and the doping is activated by rapid thermal annealing, so that the problems caused by hopping transmission and Coulomb traps in charge transport are improved, the threshold voltage is reduced, and the on-off ratio is improved. For a P-type field effect transistor, the P-type doping enhances hole transport, effectively improves the saturation current, and suppresses electron transport, so that the power consumption is reduced when the transistor is turned off. The doping method is based on a solution method and is simple in process and low in preparation cost, can be applied to large-scale production, and has a good application prospect in flexible and portable electronic devices.

Description

Technical Field

[0001] This invention relates to a method for P-type doping of the semiconductor layer of an organic field-effect transistor, specifically a method for channel doping of polymer transistors by solution method in a water-oxygen atmosphere, belonging to the field of organic transistor fabrication. Background Technology

[0002] Organic field-effect transistors (OFETs) were invented in the 1980s and gained attention for their ability to realize thin and flexible circuits over large areas at low processing temperatures. Today, OFETs are widely used to drive electronic ink displays, printed RFID tags, and flexible electronic devices. Organic semiconductor materials are classified into small organic molecule semiconductor materials and organic polymer semiconductor materials based on the repeatability of their molecular structural units. Small organic molecule semiconductor materials are generally composed of relatively large π-π conjugated systems. Red fluorene, pentacene, and hexaphenyl are commonly used small organic molecule semiconductor materials in experiments. Generally speaking, small organic molecule materials have a fixed molecular weight, giving them an advantage in compound purity. Furthermore, the fixed molecular structure and tightly ordered arrangement of molecules in small organic molecule materials are beneficial for carrier transport. Organic polymer materials, also known as polymers or high-polymer materials, are generally composed of two or more molecules or molecular groups bonded by covalent bonds to form macromolecules with multiple repeating monomer units. Polymer materials can be easily processed into large-area thin films, exhibiting thicknesses exceeding 0.1 cm². 2 V -1 s -1 The charge carrier mobility of field-effect transistors. Compared to fragile small-molecule single-crystal FETs, polymer semiconductors have superior machinability and stretchability, providing additional advantages for flexible electronic devices. However, the charge carrier mobility in polymer devices is generally low due to the high number of impurities and defects in these materials, as well as the lack of macroscopic order. Common organic polymer materials include polythiophenes (such as P3AT, P3HT), polyfluorenes (such as PFO), copolymers of PFO and dithiophene (F8T2), pyrrolopyrrole diones (such as DPPT-TT), etc.

[0003] Currently, the carrier mobility and current on / off ratio of field-effect transistors based on small molecules and conjugated polymers are comparable to those of field-effect transistors without dielectrics. High dielectric constant organic insulating materials have also laid a solid foundation for their fabrication. Field-effect transistor fabrication technology is also developing towards process simplification and cost reduction.

[0004] Analogous to silicon devices, to fabricate ideal functional devices with different charge transport polarities on the same substrate, a deeper understanding of doping techniques for organic materials is needed. However, organic field-effect transistors (OFETs), as the cornerstone of future organic electronics, are almost excluded from high-concentration doping due to the severe uncontrollable diffusion of doping [1]. Compared to the parts per million (ppm) typically required for inorganic materials, high doping leads to performance degradation, especially on / off ratio decay. Recent breakthroughs in organic semiconductors and doping techniques suggest that doping can also be a key driver of high-performance OFETs [2].

[0005] 【1】]K.Kang,S.Watanabe,K.Broch,A.Sepe,A.Brown,I.Nasrallah,M.Nikolka,ZPFei,M.Heeney,D.Matsumoto ,K.Marumoto,H.Tanaka,S.Kuroda,H.Sirringhaus,Nat.Mater.2016,15,896.(doi.org / 10.1038 / nmat4634);

[0006] 【2】X.Gu,L.Shaw,K.Gu,MFToney,Z.Bao,Nat.Commun.2018,9,534.(doi.org / 10.1038 / s41467-018-02833-9).

[0007] However, the technical problem that this invention needs to solve is how to effectively dopant, such as how the type of dopant, doping method, doping concentration, annealing time and annealing temperature affect transistor threshold voltage, mobility, contact resistance and other parameters, and how to produce organic field-effect transistors with better performance by improving effective doping. Summary of the Invention

[0008] The purpose of this invention is to provide a P-type doping method for organic field-effect transistor semiconductor layers. P-type channel doping is performed in a water-oxygen atmosphere using a solution method, which improves the problems caused by jump transport and Coulomb traps in charge transport, enhances hole transport, thereby reducing the threshold voltage and increasing the on / off ratio. This doping method is based on solution operation, has a simple process, low preparation cost, and is suitable for large-scale production. It has a promising future for applications in flexible and portable electronic devices.

[0009] The technical solution of the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for P-type doping of an organic field-effect transistor semiconductor layer, wherein the organic semiconductor layer thin film is doped in a solution phase under an atmospheric water-oxygen environment, specifically including the following steps: using 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ) as a solute and the orthogonal solvent of the organic semiconductor layer as the solvent of F4-TCNQ, spin-coating in a water-oxygen environment, and then annealing at a temperature of 50 to 100°C for 5 to 10 minutes to dope and activate the organic layer thin film, thereby obtaining an organic semiconductor layer thin film;

[0011] By using spin coating and thermal annealing processes in a water-oxygen environment to dope organic thin films, the threshold voltage can be effectively reduced, electron transport can be suppressed, and the device switching ratio can be improved. Furthermore, the complex water-oxygen environment does not create many traps at the doping interface, nor does it cause significant structural damage to the device microstructure, so the mobility is not greatly affected.

[0012] Preferably, the organic semiconductor layer material is poly(dithiophene-pyrrolopyrrole-dione-thiophene) (DPPT-TT), and the orthogonal solvent is butyl acetate. The F4-TCNQ used in this invention is a common P-type dopant. Due to its deep LUMO (Lowest Unoccupied Molecular Orbital) (-5.2 eV), which is smaller than or close to many OSC HOMOs (Highest Occupied Molecular Orbital), electrons can be transferred from OSC HOMO to F4-TCNQLUMO, resulting in P-type doping. In a water-oxygen environment, the charge transfer reaction between the organic semiconductor material and oxygen molecules leads to an increase in P-type doping. Annealing F4-TCNQ in a water-oxygen environment can further enhance the charge transfer reaction between F4-TCNQ and DPPT-TT.

[0013] This invention uses the orthogonal solvent NBA for the organic semiconductor DPPT-TT to dissolve the dopant F4-TCNQ. The preferred specific operation is to dissolve it by heating at 80°C for 12 hours in a water-oxygen environment. Previously, commonly used organic solvents such as chlorobenzene (CB), 1,2-dichlorobenzene, N,N-dimethylformamide, butyl acetate, and acetonitrile have a dissolving effect on the organic semiconductor DPPT-TT. During the spin coating process, the organic semiconductor film structure and thickness will be damaged, affecting the standardization of device fabrication.

[0014] The spin-coating environment described in this invention is an atmospheric environment, specifically a water-oxygen environment. The atmospheric environment is rich in water and oxygen, causing a charge transfer reaction between the organic semiconductor material and oxygen molecules, leading to an increase in P-type doping. Previous doping processes were based on a nitrogen atmosphere in a glove box, isolating the influence of water and oxygen. DPPT-TT is a bipolar semiconductor material where both electrons and holes can be major charge carriers. However, sometimes we want to minimize current when the transistor is reverse biased, thereby reducing the static power consumption of complementary symmetry transistor circuits. Therefore, in P-type field-effect transistors, it is desirable to suppress electron transport. Annealing F4-TCNQ in a water-oxygen environment can further enhance the charge transfer reaction between F4-TCNQ and DPPT-TT, thereby suppressing electron transport.

[0015] Furthermore, the spin coating and thermal annealing steps are preferably performed at a speed of 1000 rpm / s for 60 seconds, followed by annealing at 80°C for 5 minutes. The spin coating speed of the dopant solution is to uniformly wet the semiconductor film and remove excess solution. Unlike the mixed solution method, which damages the molecular structure of the DPPT-TT film, doping after the DPPT-TT film is formed can reduce the impact on the molecular structure of the DPPT-TT film. The dopant introduced by doping will undergo ground-state charge transfer with the polymer molecules, generating polarons or bipolarons on the polymer film. The dopant anions remain in the film in the form of counterions. The annealing time and temperature of the dopant play an important role in effectively controlling the doping depth and gradient of the dopant. If the annealing temperature is too high or the annealing time is too long, the dopant molecules on the surface will diffuse from the DPPT-TT film surface into the depth of the film, causing structural disorder, forming deep-level traps, resulting in an increase in threshold voltage and a decrease in mobility. If the annealing temperature is too low or the annealing time is too short, the dopant will not be effectively activated, the doping efficiency will decrease, and the threshold voltage will not decrease significantly. Annealing at 80℃ for 5 minutes can more effectively activate the dopant, effectively reduce the threshold voltage without affecting the mobility, increase the current density, suppress electron transport, and improve the on / off ratio.

[0016] Furthermore, the preferred ratio of the solute F4-TCNQ to the solvent butyl acetate is 1 mg: 1 ml.

[0017] Secondly, the present invention provides an organic field-effect transistor, wherein the organic semiconductor layer of the organic field-effect transistor is an organic semiconductor thin film obtained by the above-mentioned doping method; preferably, the organic field-effect transistor is a P-type top-gate bottom-contact organic field-effect transistor.

[0018] More preferably, the P-type top-gate bottom-contact organic field-effect transistor consists of source / drain electrodes, an organic semiconductor layer, a dielectric layer, and a gate layer. The source / drain electrodes are gold; the organic semiconductor layer is DPPT-TT-doped F4-TCNQ; the dielectric layer is PMMA; and the gate electrode is copper. The structure is simplified to Au / DPPT-TT / F4-TCNQ / PMMA / Cu. The advantage of using a top-gate structure is that a flexible substrate can be used directly, and the dielectric layer can directly act as a protective layer for the organic semiconductor layer, avoiding interference from the water and oxygen environment during subsequent characterization. The advantage of a bottom-contact structure is that it can be fabricated using high-resolution technology, and the fabricated electrodes can undergo certain surface treatments to improve contact. The charge injection area of ​​the staggered structure of the top-gate bottom contact is better than that of the coplanar structure, reducing the influence of contact resistance.

[0019] Beneficial effects:

[0020] This invention relates to a method for solution-doped P-type channel polymer field-effect transistors in a water-oxygen atmosphere. The working principle is as follows: Organic polymer transistors typically have numerous traps distributed within a polymer thin film. Charge carriers first fill the deep energy level traps to raise the Fermi level, and then charge carriers accumulate and eventually form a conductive channel. This significant charge trapping results in a very high threshold voltage Vt. T Doping, even at ultra-low levels, effectively passivates traps and reduces V. T F4-TCNQ is a common p-type dopant. Due to its deep LUMO (-5.2 eV), which is smaller than or close to many OSC HOMOs, electrons can transfer from the OSC HOMO to the F4-TCNQ LUMO, resulting in p-type doping. In a water-oxygen environment, the charge transfer reaction between the organic semiconductor material and oxygen molecules leads to an increase in p-type doping. Annealing F4-TCNQ in a water-oxygen environment can further enhance the charge transfer reaction between F4-TCNQ and DPPT-TT.

[0021] In this invention, the doping process is conducted in a water-oxygen environment to enhance hole transport. In a water-oxygen environment, the doping reaction of the dopant on the organic semiconductor, i.e., the charge transfer between dopant molecules and organic semiconductor molecules, differs significantly from that in a glove box (nitrogen environment). In a glove box, dopant activation is not sensitive to annealing time and temperature; the p-type doping of DPPT-TT films by F4-TCNQ does not significantly suppress electron transport, but it significantly enhances hole transport. In a water-oxygen environment, dopant activation is more demanding in terms of annealing time and temperature. With the presence of water and oxygen, the dopant diffusion problem caused by doping becomes more pronounced. Comparative experiments showed that annealing at 80°C for 5 minutes effectively activates the dopant.

[0022] Compared with other preparation methods, the preparation process of this invention is simple. The semiconductor materials, dopants, and dielectric layers are all prepared based on solution methods. The process is simple, low-cost, and suitable for large-scale production. It has a promising future for applications in flexible and portable electronic devices. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the structural principle of the Au / DPPT-TT / F4-TCNQ / PMMA / Cu top-gate bottom-contact transistor involved in this invention.

[0024] Figure 2a The saturation region transfer characteristics curves were obtained by using 1 mg / ml F4-TCNQ / NBA solution in anhydrous and aquatic oxygen environments for doping and undoping.

[0025] Figure 2b The saturation zone transfer characteristic curves are shown for different annealing temperatures and times.

[0026] Figure 2c Output characteristic curves of transistors fabricated under water and oxygen conditions;

[0027] Figure 3 This is the transfer characteristic curve in the saturation region, where I D Logarithmic coordinates These are linear coordinates. Detailed Implementation

[0028] The concept and specific structure of the present invention will be further described below with reference to the accompanying drawings to fully understand the purpose, features, and effects of the invention. Specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of," etc., will be understood to include the stated elements or components, and does not exclude other elements or other components.

[0029] In the following examples, F4-TCNQ was purchased from Sigma-Aldrich with a purity of 97%, DPPT-TT is a bipolar conjugated DA polymer material purchased from Ruixun, the organic solvents NBA and DCB were purchased from Sigma-Aldrich with a purity of 99%, the semiconductor parameter analyzer B1500A was purchased from Agilent, and the vapor deposition apparatus was purchased from Shenyang Chuangyi Vacuum Technology Co., Ltd. The sources of raw materials and equipment are shown in Tables 1 and 2 below:

[0030]

[0031]

[0032] Table 2 Equipment used in device fabrication

[0033] Equipment Name Manufacturer Ultrasonic cleaning machine Fuyang Ultrasonic Cleaning Equipment Co., Ltd. Programmable glue baking machine Jiangsu Leibo Scientific Instruments Co., Ltd. Laboratory heating table Dalong Xingchuang Experimental Instruments (Beijing) Co., Ltd. Ultraviolet ozone cleaner (U / Vozone) Novascan Vacuum Evaporation Equipment Shenyang Chuangyi Vacuum Technology Co., Ltd. EZ4-S Spin Coator Jiangsu Leibo Scientific Instruments Co., Ltd. probe platform Shenzhen Sendongbao Technology Co., Ltd. B1500A Semiconductor Analyzer Agilent optical microscope Shenzhen Ausmicro Optical Instruments Co., Ltd. glove box Vigor electronic scale Shanghai Jingke Tianmei Scientific Instruments Co., Ltd. pipette Dalong Xingchuang Experimental Instruments (Beijing) Co., Ltd.

[0034] Example 1: Doping under water and oxygen atmosphere conditions

[0035] This embodiment relates to a process for P-type channel doping via solution method in a water-oxygen atmosphere and a method for fabricating polymer field-effect transistors, specifically including the following steps:

[0036] 1) Substrate cleaning: Glass slides are used as substrates. The glass slides are placed in beakers of deionized water (DI) and ethanol, respectively, and cleaned using an ultrasonic cleaner for 5-10 minutes. This process is repeated twice. Then, the surface of the glass slides is dried using high-purity nitrogen (99.99% purity), and finally, the slides are thoroughly dried on a heating stage at 100°C for 20 minutes before use as substrates.

[0037] 2) Surface treatment: The dried glass slides are cleaned with a UV ozone cleaner for 30 minutes to remove organic residues on the surface of the glass slides and improve the hydrophilicity of the glass slide surface, so that the organic semiconductor layer film can be better prepared.

[0038] 3) Fabrication of source and drain electrodes: Due to its environmental stability and ease of photolithography patterning, gold is used for hole and electron injection electrodes. The processed glass slide is placed on a sample plate, and a mask is then attached to the surface of the glass slide before it is placed in an evaporation apparatus; under a vacuum degree <10... -5 Under the conditions of Pa, a 5-nanometer layer of metallic nickel (Ni) is first deposited as an adhesion layer using physical vapor deposition to better ensure the adhesion of the subsequently deposited gold electrode and prevent damage. Next, metallic gold (Au) is deposited as the electrode with a thickness of 50 nanometers. After the electrode is prepared, the mask is removed to obtain the gold electrode with the desired pattern.

[0039] 4) Electrode Surface Treatment: The work function and surface energy of the gold electrode can vary significantly depending on the surface treatment method. Cleaning with acetone, isopropanol, plasma, or a UV / V ozone cleaner can adjust the work function and implantation barrier of the gold electrode. Using a UV / V ozone cleaner for 30 minutes, compared to other methods, effectively reduced the work function of the gold electrode, decreased the energy level difference between the gold electrode and the organic semiconductor layer DPPT-TT, thereby reducing the implantation barrier and forming an ohmic contact.

[0040] 5) Preparation of organic semiconductor layer: In a glove box under nitrogen atmosphere, organic semiconductor (DPPT-TT) was dissolved in dichlorobenzene (DCB), and then the solution was heated at 80°C for 12 h to accelerate dissolution; then DPPT-TT solution (5 mg / ml) was spin-coated onto the surface of a glass substrate with gold electrodes deposited, and then annealed at 80°C for 10 min and at 200°C for 1 h to prepare organic thin film.

[0041] 6) Doping the organic semiconductor layer: In a fume hood with water and oxygen, the P-type dopant F4-TCNQ was dissolved in the orthogonal solvent NBA of the organic semiconductor DPPT-TT, and then the solution was heated at 80°C for 12 h to accelerate dissolution; then the F4-TCNQ solution (1 mg / ml) was spin-coated onto the surface of the DPPT-TT film, and then annealed at 80°C for 5 min to activate the doping.

[0042] 7) Preparation of dielectric layer: First, polymethyl methacrylate (PMMA) is dissolved in NBA, and then the solution is heated at 80°C for 12 hours; then the doped sample is placed in a glove box, and PMMA solution (80 mg / ml) is spin-coated on the sample surface, followed by annealing at 80°C for 2 hours to form PMMA dielectric layer.

[0043] 8) Gate fabrication: First, place the sample with the prepared dielectric layer on a sample plate. Then, attach a mask to the surface of the dielectric layer and place the silicon wafer on the sample plate into an evaporator; under a vacuum degree <10 -5 Under Pa conditions, copper gates were deposited using physical vapor deposition to a thickness of 80 nanometers; after the copper gate fabrication was completed, a copper gate with the desired pattern was obtained. The final fabricated result is as follows... Figure 1 The transistor shown is an Au / DPPT-TT / F4-TCNQ / PMMA / Cu transistor with top-gate bottom contact.

[0044] Comparative Example 1: Undoped under anhydrous oxygen atmosphere

[0045] The difference from the operation steps of Example 1 is that step 6) is omitted in which the organic semiconductor layer is doped, and the dielectric layer is directly prepared on the organic semiconductor layer.

[0046] Comparative Example 2: Doping under anhydrous oxygen atmosphere

[0047] The difference from the operation steps in Example 1 is that the doping process in step 6) takes place in a glove box, and the atmosphere of the glove box is an anhydrous oxygen and nitrogen (N2) environment.

[0048] Comparative Example 3: Undoped under water and oxygen atmosphere conditions

[0049] The difference from the operation steps in Example 1 is that after step 5), the organic semiconductor layer is exposed to a water-oxygen atmosphere for the same duration as in step 6), but the organic semiconductor layer is not doped as in step 6). The dielectric layer is then directly fabricated on the organic semiconductor layer in the same way as in step 7).

[0050] Figure 2a The saturation region transfer characteristic curves of transistors fabricated in Example 1, Comparative Examples 1-3, and Comparative Examples 3 under anhydrous and oxygen-free environments and in water-oxygen environments, respectively, using 1 mg / ml F4-TCNQ / NBA solution for doping and undoping, are shown. The specific testing instrument used was a B1500A. Figure 2a It can be clearly observed that doping can reduce the threshold voltage and effectively increase the current density, especially in a water-oxygen environment where the participation of water and oxygen can improve the on / off ratio of the doped device. Actual data is extracted using the saturation region formula shown below, and the corresponding curves are as follows. Figure 3 As shown:

[0051]

[0052] Where: W is the transistor channel width, L is the transistor channel length, and C... i The capacitance of the dielectric layer per unit area is μ. sat V is the mobility of the field effect in the saturation region. T This is the threshold voltage.

[0053]

[0054] We found that the second half of the formula after taking the square root exhibits good linearity. At this point, the slope of the fitted tangent line is... At this point, the mobility of the saturated region field effect can be obtained:

[0055]

[0056] Threshold voltage V T It is the gate voltage V applied when the conductive channel of the polymer field-effect transistor is just turned on. G Saturation threshold voltage V T It can be obtained by extending the tangent of the linear fitting in the opposite direction to the X-axis V. G The focus was estimated.

[0057] The calculation results are shown in the table below:

[0058]

[0059] In Example 1, step 6 involves spin-coating an F4-TCNQ solution onto the DPPT-TT thin film surface and annealing it at a certain temperature for a certain time to activate the doping. As a comparison, corresponding transistor devices were fabricated by changing the annealing temperature and time in Example 1, resulting in Examples 2-6. The specific annealing temperature and time for each example are shown in the table below. Figure 2b The saturation region transfer characteristic curves at different annealing temperatures and times clearly show that the dopant F4-TCNQ is extremely sensitive to water and oxygen environments. Annealing at 100℃ for 10 minutes significantly leads to dopant molecule diffusion, resulting in an increase in threshold voltage, a decrease in mobility, and a severe drop in on / off ratio. Based on comparative analysis, annealing at 80℃ for 5 minutes is a better choice. The specific calculation results are shown in the table below.

[0060]

[0061] like Figure 2c The output characteristic curves of the transistors fabricated in a water-oxygen environment are shown. The electrical characteristics of the devices were tested using a probe station connected to an Agilent B1500A semiconductor parameter analyzer. The tests included IV output curves, saturation region transfer characteristic curves, and linear region transfer characteristic curves.

[0062] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for p-type doping of a semiconductor layer in an organic field-effect transistor, characterized in that, Includes the following steps: Using 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone F4-TCNQ as the solute and the orthogonal solvent of the organic semiconductor layer as the solvent of F4-TCNQ, the film was spin-coated in a water-oxygen environment and then subjected to low-temperature thermal annealing to obtain a doped organic semiconductor layer film. The organic semiconductor layer material is DPPT-TT, and the orthogonal solvent is butyl acetate; The specific steps for low-temperature heat annealing are annealing at 80°C for 5 minutes.

2. The method for p-type doping of the semiconductor layer of an organic field-effect transistor as described in claim 1, characterized in that, The dopant F4-TCNQ was dissolved using butyl acetate, an orthogonal solvent for the organic semiconductor DPPT-TT, by heating at 80°C for 12 hours in a water-oxygen environment.

3. The method for p-type doping of the semiconductor layer of an organic field-effect transistor as described in claim 1, characterized in that, The spin coating step in the water-oxygen environment specifically involves spin coating the F4-TCNQ solution onto the semiconductor thin film at a speed of 1000 rpm for 60 seconds in the water-oxygen environment.

4. The method for p-type doping of the semiconductor layer of an organic field-effect transistor as described in claim 1, characterized in that, The ratio of F4-TCNQ to butyl acetate is 1 mg: 1 ml.

5. An organic field-effect transistor, characterized in that, The organic semiconductor layer of the organic field-effect transistor is a doped organic semiconductor thin film obtained by the doping method described in any one of claims 1-4.

6. The organic field-effect transistor as described in claim 5, characterized in that, Organic field-effect transistors are P-type organic field-effect transistors with top-gate bottom contact.

7. The organic field-effect transistor as described in claim 6, characterized in that, The P-type top-gate bottom-contact organic field-effect transistor consists of source and drain electrodes, the doped organic semiconductor layer, a dielectric layer, and a gate layer, wherein the source and drain electrodes are gold, the dielectric layer is PMMA, and the gate electrode is copper.

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