A flexible organic thin film transistor and a preparation method and application thereof

Abstract

The application discloses a flexible organic thin film transistor and a preparation method and application thereof, and belongs to the technical field of thin film transistors. The preparation method comprises sequentially arranging a gate electrode, an aluminum oxide gate dielectric, a self-assembled monolayer, a patterned organic semiconductor layer and a source-drain electrode on the surface of a flexible substrate. The magnetron sputtering of the aluminum oxide gate dielectric satisfies at least one of the following parameters: A. the temperature of the flexible substrate is 20-180 DEG C; B. the atmosphere is a mixture of argon and oxygen at a volume ratio of 0.5-1.5:1; C. the power of the direct current power supply used is 45-55 W; D. the air pressure is 0.4-0.6 Pa; and E. the distance between the flexible substrate and the target material is 10-12 cm. The preparation method has the characteristics of simplicity, reliability and high repeatability, and the obtained flexible organic thin film transistor has high frequency stability. The application further provides the flexible organic thin film transistor prepared by the above preparation method and the application thereof.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film transistors, in particular to a flexible organic thin film transistor and a preparation method and application thereof. BACKGROUND

[0002] Flexible electronics is a new electronic technology that prepares organic / inorganic material electronic devices on a flexible / stretchable substrate, and has great application prospects in the fields of medical health, flexible display, wearable devices and Internet of Things. Among them, the flexible organic thin film transistor is an important device for preparing flexible circuits, and a low-cost, high-stability and large-scale preparation process is the current direction of flexible organic thin film transistor technology exploration.

[0003] The dielectric material is an important component of the organic thin film transistor and directly affects the overall performance of the organic thin film transistor. Aluminum oxide (Al2O3) is a dielectric material with good stability and high dielectric constant, and a nano-thickness of aluminum oxide has good transparency and flexibility.

[0004] In the traditional technology, the preparation method of the aluminum oxide film requires a high temperature, or even if low-temperature preparation can be achieved, it is difficult to prepare an ultra-thin thickness of the aluminum oxide film under low-temperature conditions. Therefore, it will seriously affect the overall performance of the obtained organic thin film transistor, especially the frequency stability and the mobility. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a preparation method of a flexible organic thin film transistor, which has the characteristics of simplicity, reliability and high repeatability, and the obtained flexible organic thin film transistor has high frequency stability and mobility.

[0006] The present application also provides a flexible organic thin film transistor prepared by the above preparation method.

[0007] The present application also provides the application of the above preparation method.

[0008] According to the embodiment of the first aspect of the present application, a preparation method of a flexible organic thin film transistor is provided, and the preparation method comprises the following steps:

[0009] S1. A gate electrode is arranged on the surface of a flexible substrate;

[0010] S2. A gate dielectric of aluminum oxide is arranged on the surface of the gate electrode by a magnetron sputtering method;

[0011] S3. A self-assembled monolayer is arranged on the surface of the gate dielectric of aluminum oxide;

[0012] S4. A patterned organic semiconductor layer is arranged on the surface of the self-assembled monolayer;

[0013] S5. Setting a source electrode and a drain electrode on the surface of the organic semiconductor layer;

[0014] In step S2, the magnetron sputtering method for setting the aluminum oxide gate dielectric satisfies at least one of the following process parameters:

[0015] A. The atmosphere is a mixture of argon and oxygen, and the volume ratio of the argon and oxygen is 0.5-1.5:1;

[0016] B. A direct current power source is used, and the power of the direct current power source is 45-55 W;

[0017] C. The working pressure is 0.4-0.6 Pa;

[0018] D. The distance between the part obtained in step S1 and the target material used is 10-12 cm;

[0019] E. The temperature of the part obtained in step S1 is 20-180°C.

[0020] According to the preparation method of the embodiments of the present application, at least the following beneficial effects are achieved:

[0021] In the preparation method provided by the present application, by adjusting the parameters of magnetron sputtering, an ultrathin high-quality patterned aluminum oxide gate dielectric can be prepared at low temperature or room temperature. The preparation method is simple, reliable, and has high repeatability, and is suitable for various different flexible substrates. The obtained flexible organic thin film transistor has the advantage of high mobility (≥4.25 cm 2 V -1 s -1 ). The obtained aluminum oxide gate dielectric has high dielectric constant and frequency stability, thereby improving the mobility and frequency stability of the obtained flexible organic thin film transistor.

[0022] Further, in the preparation method provided by the present application, multiple steps are designed to be patterned, which makes the preparation method provided by the present application more conducive to the design of complex circuits, and greatly reduces the process complexity.

[0023] According to some embodiments of the present application, the preparation method further comprises, before step S1, cleaning a glass sheet and sequentially setting a sacrificial layer and a flexible substrate on the surface of the obtained cleaned glass sheet. The glass sheet serves as a temporary substrate, and when the flexible organic thin film transistor is prepared, the temporary substrate can be peeled off according to needs.

[0024] According to some embodiments of the present application, the cleaning method of the glass sheet comprises the following steps: soaking the glass sheet in the piranha solution, ultrasonic cleaning with water, ultrasonic cleaning with isopropyl alcohol, post-rinsing after ultrasonic cleaning with ethanol, and cleaning with oxygen plasma. The piranha solution is prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a volume ratio of 7:3. The soaking time in the piranha solution is 1.5-2.5 hours, for example, specifically about 2 hours.

[0025] According to some embodiments of the present application, the method for setting the sacrificial layer comprises spin coating. The spin coating speed for setting the sacrificial layer is 4500-5500 rpm, for example, specifically about 5000 rpm. The spin coating time for setting the sacrificial layer is 30-60 seconds, for example, specifically about 40 seconds.

[0026] According to some embodiments of the present application, the material of the sacrificial layer comprises fluoride.

[0027] According to some embodiments of the present application, the fluoride specifically comprises at least one of 3M Novec 7100 and 3M Novec 1700. Among them,

[0028] The components of 3M Novec 7100 include: perfluorobutyl methyl ether (CAS: 163702-08-7), 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane (CAS: 163702-07-6).

[0029] The components of 3M Novec 1700 include: methyl nonafluoroisobutyl ether (CAS: 163702-08-7), methyl nonafluorobutyl ether (CAS: 163702-07-6), fluorine-containing aliphatic polymer.

[0030] According to some embodiments of the present application, in step S1, the thickness of the flexible substrate is 2-5 μm. For example, specifically 2-3 μm. Further specifically, about 2.5 μm.

[0031] According to some embodiments of the present application, in step S1, the flexible substrate is a transparent substrate.

[0032] According to some embodiments of the present application, in step S1, the flexible substrate is formed by a flexible layer and a photoresist layer arranged in a stack.

[0033] According to some embodiments of the present application, the material of the flexible layer comprises at least one of Parylene, PET, PEN and PI.

[0034] According to some embodiments of the present application, the thickness of the flexible layer is 0.5-2 μm. For example, specifically 1-1.5 μm.

[0035] According to some embodiments of the present application, the method for setting the flexible layer comprises plating and annealing in sequence. The plating for setting the flexible layer is performed by a plating instrument. The annealing for setting the flexible layer is performed at a temperature of 150-200℃, for example, about 180℃. The annealing for setting the flexible layer is performed for a time period of 0.5-1h, for example, about 40min.

[0036] According to some embodiments of the present application, the thickness of the photoresist layer is 0.5-1.5μm. For example, about 1μm.

[0037] According to some embodiments of the present application, the material of the photoresist layer comprises SU-8 photoresist.

[0038] According to some embodiments of the present application, the method for setting the photoresist layer comprises spin coating, baking, exposure and annealing in sequence. The spin coating for setting the photoresist layer is performed at a speed of 4500-5500rpm, for example, about 5000rpm. The spin coating for setting the photoresist layer is performed for a time period of 50-80s, for example, about 60s. The baking for setting the photoresist layer is performed at a temperature of 80-100℃, for example, about 90℃. The baking for setting the photoresist layer is performed for a time period of 1-5min, for example, about 3min. The annealing for setting the photoresist layer is performed at a temperature of 150-200℃, for example, about 180℃. The annealing for setting the photoresist layer is performed for a time period of 0.5-1.5h, for example, about 1h.

[0039] According to some embodiments of the present application, in step S1, the material of the gate electrode comprises at least one of ITO, gold and aluminum.

[0040] According to some embodiments of the present application, in step S1, the method for setting the gate electrode comprises at least one of evaporation and magnetron sputtering.

[0041] According to some embodiments of the present application, in step S1, when the material of the gate electrode is selected from the ITO, the method for setting the gate electrode comprises magnetron sputtering. The magnetron sputtering for setting the gate electrode satisfies at least one of the following process parameters:

[0042] (1) the target material is ITO;

[0043] (2) the power source is an alternating current power source, and the power is 45-55W, for example, about 50W;

[0044] (3) the distance between the target material and the flexible substrate is 8-12cm, for example, about 10cm;

[0045] (4) the atmosphere is argon;

[0046] (5) Before the atmosphere is filled, the vacuum degree in the cavity of the magnetron sputtering method is ≤4×10 -4 Pa.

[0047] (6) The working gas pressure is 0.2-0.5 Pa; for example, it can be about 0.3 Pa.

[0048] (7) The deposition time length of the magnetron sputtering is 25-35 min; for example, it can be about 30 min.

[0049] (8) The temperature of the flexible substrate is 20-180℃, for example, it can be about 25℃, 60℃, 120℃ or about 180℃.

[0050] According to some embodiments of the present application, in step S1, when the material of the gate electrode is selected from at least one of gold and aluminum, the setting method of the gate electrode comprises an evaporation method.

[0051] According to some embodiments of the present application, in step S1, the setting of the gate electrode is performed with the assistance of a mask. The mask is provided with a cross mark.

[0052] According to some embodiments of the present application, in step S1, the thickness of the gate electrode is 30-100 nm. For example, it can be about 50 nm, 80 nm or about 100 nm.

[0053] According to some embodiments of the present application, in step S2, parameters A-E are simultaneously satisfied.

[0054] According to some embodiments of the present application, in step S2, the magnetron sputtering method for setting the aluminum oxide gate dielectric is provided, and the target material is high-purity aluminum.

[0055] According to some embodiments of the present application, in step S2, the magnetron sputtering method for setting the aluminum oxide gate dielectric is provided, and the deposition time length is 100-200 min. For example, it can be 120-150 min. For example, it can be about 130 min. In actual production, the thickness of the aluminum oxide gate dielectric can be adjusted by adjusting the time length.

[0056] According to some embodiments of the present application, in step S2, the magnetron sputtering method for setting the aluminum oxide gate dielectric is provided, and before the atmosphere is filled, the vacuum degree in the cavity is ≤4×10 -4 Pa.

[0057] According to some embodiments of the present application, in step S2, the magnetron sputtering method for setting the aluminum oxide gate dielectric is provided, and / or the temperature of the flexible substrate when the gate electrode is set in step S1 is 25-40℃.

[0058] According to some embodiments of the present invention, in step S2, the volume ratio of argon to oxygen in the atmosphere of the magnetron sputtering method for the alumina gate medium is approximately 1:1.

[0059] According to some embodiments of the present invention, in step S2, the DC power supply used in the magnetron sputtering method for setting the alumina gate dielectric is approximately 50W.

[0060] According to some embodiments of the present invention, in step S2, the working gas pressure in the magnetron sputtering method for setting the alumina gate medium is approximately 0.5 Pa.

[0061] According to some embodiments of the present invention, in step S2, in the magnetron sputtering method of setting the alumina grid medium, the distance between the component obtained in step S1 and the target material used is about 10cm.

[0062] According to some embodiments of the present invention, in step S2, the temperature of the component obtained in step S1 in the magnetron sputtering method of the alumina gate dielectric is set to 25°C to 150°C. For example, it may be about 60°C or about 120°C.

[0063] According to some embodiments of the present invention, in step S2, the alumina gate dielectric is set with the assistance of a photomask. The photomask has cross-shaped markings. This allows the alumina gate dielectric to be aligned with the gate electrode.

[0064] According to some embodiments of the present invention, in step S2, the thickness of the alumina gate dielectric is 25–80 nm. For example, it can be about 30 nm, 35 nm, or about 50 nm.

[0065] According to some embodiments of the present invention, in step S3, the method for setting the self-assembled monolayer includes immersing the component obtained in step S2 in a solution containing the self-assembled monolayer.

[0066] According to some embodiments of the present invention, the self-assembled monomolecule has a terminal phosphonic acid group. Specifically, it may be at least one of 12-cyclohexyldodecylphosphonic acid, octadecylphosphonic acid, and hexadecylphosphonic acid.

[0067] According to some embodiments of the present invention, the concentration of the solution of the self-assembled monomolecules is 1–5 mM. For example, it can be 2–3 mM.

[0068] According to some embodiments of the present invention, the soaking time is 10 to 15 hours. For example, it can be about 12 hours.

[0069] According to some embodiments of the present invention, in step S3, the thickness of the self-assembled monolayer is 0.5 to 1.5 nm. Depending on the type of molecule, it may specifically be about 1 nm.

[0070] According to some embodiments of the present application, the material of the self-assembled monolayer includes 12-cyclohexyldodecyl-phosphonic acid (CDPA).

[0071] According to some embodiments of the present application, in step S4, the method of setting the organic semiconductor layer includes thermal evaporation.

[0072] According to some embodiments of the present application, in step S4, the thermal evaporation of the organic semiconductor layer is performed at a speed of For example, it can be about In actual production, the temperature of the thermal evaporation is determined according to the boiling point of the raw material.

[0073] According to some embodiments of the present application, in step S4, the setting of the organic semiconductor layer is performed with the aid of a mask. The mask is provided with a cross mark, so that it can be aligned with the aforementioned gate electrode, gate dielectric of aluminum oxide, etc.

[0074] According to some embodiments of the present application, in step S4, the thickness of the organic semiconductor layer is 40-60 nm. For example, it can be about 50 nm.

[0075] According to some embodiments of the present application, in step S4, the material of the organic semiconductor layer includes at least one of Ph-BTBT-12 (2-(4-dodecyl phenyl)[1]benzothieno[3,2-b]benzothiophene), DPA (2,6-Diphenylanthracene), C8-BTBT (2,7-diocty[1]benzothieno[3,2-b]benzothiophene), Pentacene and TIPS-Pentacene.

[0076] According to some embodiments of the present application, in step S5, the method of setting the source electrode and the drain electrode includes thermal evaporation.

[0077] According to some embodiments of the present application, in step S5, the thermal evaporation of the source electrode and the drain electrode is performed at a speed of For example, it can be about

[0078] According to some embodiments of the present application, in step S5, the setting of the source electrode and the drain electrode is performed with the aid of a mask. The mask is provided with a cross mark, so that it can be aligned with the aforementioned structure.

[0079] According to some embodiments of the present application, in step S5, the thickness of the source electrode and the drain electrode is independently selected from any value in the range of 40-60 nm. For example, it can be about 50 nm.

[0080] According to some embodiments of the present application, the material of the source electrode is gold.

[0081] According to some embodiments of the present application, the material of the drain electrode is gold.

[0082] Unless otherwise specified, the mask used in each step of the present application is made of at least one of stainless steel and polyimide (PI).

[0083] According to some embodiments of the second aspect of the present application, a flexible organic thin film transistor is provided, which is prepared by the preparation method, and has a highest mobility of ≥4.25 cm 2 V -1 s -1 .

[0084] Since the flexible organic thin film transistor uses the preparation method of all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments. That is, the flexible organic thin film transistor has a high mobility and high frequency stability.

[0085] According to some embodiments of the present application, the flexible organic thin film transistor comprises a flexible substrate, a gate electrode, an aluminum oxide gate dielectric, a self-assembled monolayer, an organic semiconductor layer, and a source electrode and a drain electrode arranged on the surface of the organic semiconductor layer, wherein the flexible substrate is composed of a flexible layer and a photoresist layer arranged in layers.

[0086] According to some embodiments of the present application, the material of the flexible layer comprises at least one of Parylene, PET, PEN and PI.

[0087] According to some embodiments of the present application, the thickness of the flexible layer is 0.5-2 μm. For example, it can be 1-1.5 μm.

[0088] According to some embodiments of the present application, the thickness of the photoresist layer is 0.5-1.5 μm. For example, it can be about 1 μm.

[0089] According to some embodiments of the present application, the material of the photoresist layer comprises SU-8 photoresist.

[0090] According to some embodiments of the present application, the material of the gate electrode comprises at least one of ITO, gold and aluminum.

[0091] According to some embodiments of the present application, the thickness of the gate electrode is 30-100 nm. For example, it can be specifically about 80 nm or about 100 nm.

[0092] According to some embodiments of the present application, the thickness of the aluminum oxide gate medium is 25-80 nm. For example, it can be specifically about 30 nm, 35 nm or about 50 nm.

[0093] According to some embodiments of the present application, the thickness of the self-assembled monolayer is 0.5-1.5 nm. For example, it can be specifically about 1 nm.

[0094] According to some embodiments of the present application, the material of the self-assembled monolayer includes at least one of 12-cyclohexyldodecyl-phosphonic acid (CDPA), octadecyl phosphonic acid and hexadecyl phosphonic acid.

[0095] There is a chemical reaction between the aluminum oxide gate medium and the self-assembled monolayer (e.g. CDPA). The reaction forms a chemical bond between CDPA and the aluminum oxide gate medium and covers on it, which is beneficial to the growth of semiconductor grains in the organic semiconductor layer.

[0096] According to some embodiments of the present application, the thickness of the organic semiconductor layer is 40-60 nm. For example, it can be specifically about 50 nm.

[0097] According to some embodiments of the present application, the material of the organic semiconductor layer includes at least one of Ph-BTBT-12 (2-(4-dodecyl phenyl)[1]benzothieno[3,2-b]benzothiophene), DPA (2,6-Diphenylanthracene), C8-BTBT (2,7-diocty[1]benzothieno[3,2-b]benzothiophene), Pentacene and TIPS-Pentacene.

[0098] According to some embodiments of the present application, the thickness of the source electrode and the drain electrode is independently selected from any value ≥20 nm. For example, it can be specifically about 40 nm, 50 nm or about 60 nm.

[0099] According to some embodiments of the present application, in the flexible organic thin film transistor, the material of the self-assembled monolayer is selected from CDPA, and the material of the organic semiconductor layer is selected from Ph-BTBT-12. As a result, a synergy between the two and the aluminum oxide gate medium can significantly improve the mobility.

[0100] According to some embodiments of the present application, the material of the source electrode is gold.

[0101] According to some embodiments of the present application, the material of the drain electrode is gold.

[0102] According to some embodiments of the third aspect of the present application, the application of the preparation method in the preparation of medical devices, flexible display devices, wearable devices or the construction of Internet of Things is provided.

[0103] Since the application adopts all the technical solutions of the preparation method of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0104] Unless otherwise specified, "at least one" mentioned in the present application means that the number is ≥1, for example, it can be any integer from 1 to 8, and further specifically can be 1, 2, 3, 4 or 5.

[0105] Unless otherwise specified, "about" in the present application actually means that the allowed error is within ±2%, for example, about 100 actually means 100±2%×100.

[0106] Unless otherwise specified, "between" in the present application includes the number, for example, "between 2 and 3" includes the end point values 2 and 3.

[0107] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0108] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0109] Figure 1 is a structural schematic diagram of the component obtained in step S5 of embodiment 1 of the present application.

[0110] Figure 2 is an XPS spectrum of the aluminum oxide gate medium obtained in embodiment 1 of the present application.

[0111] Figure 3 is the transfer characteristic curve of the flexible organic thin film transistor obtained in embodiment 1 of the present application.

[0112] Figure 4 is the capacitance frequency characteristic curve of the aluminum oxide gate medium obtained in embodiment 1 of the present application.

[0113] Figure 5 is the transfer characteristic curve of the flexible organic thin film transistor obtained in embodiment 2 of the present application.

[0114] REFERENCE NUMERALS:

[0115] Glass sheet 100, Sacrificial layer 200, Flexible substrate 300, Flexible layer 310, Photoresist layer 320, Gate electrode 400, Alumina gate dielectric 500, Self-assembled monolayer 600, Organic semiconductor layer 700, Source electrode 810, Drain electrode 820. DETAILED DESCRIPTION

[0116] The concept and the technical effects of the present application will be described clearly and completely in combination with the embodiments below, so as to fully understand the objects, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0117] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0118] Embodiment 1

[0119] In this example, a flexible organic thin film transistor is prepared, which has the structure of being arranged in a stack manner as follows:

[0120] Flexible substrate 300, gate electrode 400, alumina gate dielectric 500, self-assembled monolayer 600, organic semiconductor layer 700, source electrode 810 and drain electrode 820 arranged on the surface of the organic semiconductor layer 700. The flexible substrate 300 is composed of the flexible layer 310 and the photoresist layer 320 arranged in a stack manner.

[0121] The preparation steps of the flexible organic thin film transistor in this example are as follows:

[0122] S1. Arranging gate electrode 400:

[0123] S1a. Treating temporary substrate (glass sheet 100): selecting clean glass sheet, preparing piranha solution according to the volume ratio of H2O2:H2SO4=3:7; wherein the concentration of H2O2 is 30%, and the concentration of H2SO4 is 98%. Soaking the clean glass sheet in the piranha solution for 2h, and then sequentially ultrasonic soaking the glass sheet in deionized water, isopropyl alcohol and ethanol for 10min, and rinsing, blowing dry, and finally cleaning using oxygen plasma machine;

[0124] S1b. Spin-coating fluorine on the glass sheet obtained in step S1a as a sacrifice layer 200, spin-coating speed 5000 rpm, time 40 s;

[0125] S1c. Setting a flexible layer 310: using Parylene coater to deposit Parylene on the surface of the sacrifice layer obtained in step S1b, annealing at 180℃ for 40 min, obtaining a flexible layer 310 with a thickness of 1.5 μm;

[0126] S1d. Setting a photoresist layer 320: spin-coating SU-8 photoresist on the surface of the flexible layer 310, spin-coating speed 5000 rpm, time 60 s, obtaining a photoresist layer 320 with a thickness of 1 μm after 90℃ baking for 3 min, exposure and 180℃ annealing for 1 h, thus obtaining a flexible substrate 300.

[0127] S1e. Depositing a 100 nm thick ITO gate electrode 400 on the flexible substrate 300 by magnetron sputtering, patterning by mask plate, cross mark on the mask plate; the magnetron sputtering parameters of this step are: ITO as target material; AC power 50 W; sample and target spacing about 10 cm; working gas argon; vacuum degree ≤4×10 -4 Pa before filling gas; working gas pressure 0.3 Pa; deposition time 30 min; the temperature of the flexible substrate obtained in step S1d is normal temperature (about 25℃).

[0128] S2. Setting an aluminum oxide gate medium 500: depositing a 30 nm thick aluminum oxide gate medium 500 on the surface of the gate electrode 400 obtained in step S1 by magnetron sputtering, aligning the mask plate by the cross mark, the preparation process parameters of the aluminum oxide gate medium 500 magnetron sputtering are: high-purity aluminum as target material; DC power 50 W; sample and target spacing about 10 cm; argon: oxygen = 3:2; vacuum degree ≤4×10 -4 Pa before filling gas; working gas pressure 0.5 Pa; deposition time 120 min; substrate temperature about 25℃. The thickness of the aluminum oxide gate medium 500 under this condition is 30 nm;

[0129] S3. Setting a 1 nm thick self-assembled monolayer 600: immersing the component obtained in step S2 in CDPA solution (solvent isopropanol, 0.3 mM) for 12 h, ultrasonic drying;

[0130] S4. Setting an organic semiconductor layer 700: depositing a 50 nm thick organic semiconductor layer 700 on the surface of the self-assembled monolayer 600 by thermal evaporation coating, aligning the mask plate by the cross mark, material Ph-BTBT-12 (CAS: 1627606-00-1), coating speed

[0131] S5. Setting source electrode 810 and drain electrode 820: using thermal evaporation to deposit source electrode 810 and drain electrode 820 with a thickness of about 50 nm on the surface of organic semiconductor layer 700, aligning the mask plate by cross mark, material is gold, and the plating speed is 0.5 A / s. The structure of the component obtained in this step is shown in Figure 1 .

[0132] S6. The component obtained in S5 is cut along the edge of glass sheet 100, and the edge is fixed by adhesive tape. The upper part of flexible substrate 300 is peeled off to obtain a flexible organic thin film transistor.

[0133] Example 2

[0134] In this example, a flexible organic thin film transistor is prepared, which is different from example 1 in that:

[0135] In S4, the material is replaced by DPA (CAS: 95950-70-2).

[0136] Test Example

[0137] In this example, the composition (using XPS), the capacitance frequency characteristic curve of the aluminum oxide gate medium obtained in the example, and the transfer characteristic curve of the flexible organic thin film transistor are tested. The test conditions of the capacitance frequency characteristic curve are room temperature, air atmosphere, and a frequency range of 40-200 kHz. The test conditions of the transfer characteristic curve of the flexible organic thin film transistor are room temperature and air atmosphere.

[0138] The composition test results are shown in Figure 2 .

[0139] The transfer characteristic curves are shown in Figure 3 and Figure 5 . The results show that the flexible organic thin film transistor obtained in example 1 of the present application is a P-type flexible organic thin film transistor with a highest mobility of 4.25 cm 2 V -1 s -1 . By using CDPA to modify the aluminum oxide gate medium, a surface beneficial to the growth of organic semiconductor crystals is provided, and the similarity between the terminal cyclohexyl of CDPA and the terminal benzene ring structure of Ph-BTBT-12 allows the crystals of Ph-BTBT-12 to be arranged regularly and have larger grains during annealing, thereby promoting the improvement of the mobility of the transistor. In example 2, the material of the semiconductor organic layer is replaced by DPA. The mobility of the obtained flexible organic thin film transistor is only 0.11 cm 2 V -1 s -1 .

[0140] The capacitance frequency characteristic curves are shown in Figure 4The results show that the alumina gate dielectric prepared by the preparation method has high frequency stability in the range of 40-200 kHz.

[0141] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. Furthermore, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for fabricating a flexible organic thin-film transistor, characterized in that, The preparation method includes the following steps: S1. A gate electrode is disposed on the surface of a flexible substrate; S2. An alumina gate dielectric is deposited on the surface of the gate electrode using magnetron sputtering. S3. A self-assembled monolayer is formed on the surface of the alumina gate dielectric; S4. A patterned organic semiconductor layer is disposed on the surface of the self-assembled monolayer; S5. A source electrode and a drain electrode are disposed on the surface of the organic semiconductor layer; In step S2, the magnetron sputtering method for the alumina gate dielectric is set to meet the following process parameters: A. The atmosphere is a mixture of argon and oxygen, and the volume ratio of argon to oxygen is 0.5~1.5:1; B. A DC power supply is used, and the power of the DC power supply is 45~55W; C. The working air pressure is 0.4~0.6 Pa; D. The distance between the component obtained in step S1 and the target material used is 10~12cm; E. The temperature of the component obtained in step S1 is 20~180℃; In step S3, the material of the self-assembled monolayer is selected from 12-cyclohexyldodecylphosphonic acid; In step S4, the material of the organic semiconductor layer is selected from Ph BTBT 12.

2. The preparation method according to claim 1, characterized in that, In step S2, the magnetron sputtering method for the alumina gate medium is set, and the deposition time is 100~200 min.

3. The preparation method according to claim 1, characterized in that, In step S2, the magnetron sputtering method for the alumina grid dielectric is set up, and the vacuum degree of the cavity is ≤4×10 before the atmosphere is filled. 4 Pa.

4. The preparation method according to claim 1, characterized in that, In step S2, the thickness of the alumina gate dielectric is 25~80nm.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, the flexible substrate is composed of a flexible layer and a photoresist layer stacked together; and / or, the thickness of the flexible substrate is 2~5μm.

6. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, the method for setting the gate electrode includes at least one of magnetron sputtering and vapor deposition.

7. The preparation method according to any one of claims 1 to 4, characterized in that, In the magnetron sputtering method for setting the gate electrode, the temperature of the flexible substrate is 20~180℃.

8. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, the material of the gate electrode includes at least one of ITO, gold, and aluminum.

9. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, the thickness of the gate electrode is 30~100nm.

10. The preparation method according to any one of claims 1 to 4, characterized in that, In step S3, the method for setting the self-assembled monolayer includes immersing the component obtained in step S2 in a solution containing self-assembled monomolecules.

11. The preparation method according to claim 10, characterized in that, The soaking time is 10-15 hours.

12. The preparation method according to claim 10, characterized in that, In step S3, the thickness of the self-assembled monolayer is 0.5~1.5 nm.

13. The preparation method according to any one of claims 1 to 4, characterized in that, In step S4, the method for setting the organic semiconductor layer includes thermal evaporation deposition.

14. The preparation method according to any one of claims 1 to 4, characterized in that, In step S4, the thickness of the organic semiconductor layer is 40~60nm.

15. The preparation method according to any one of claims 1 to 4, characterized in that, In step S5, the method for setting the source electrode and the drain electrode includes thermal evaporation coating; and / or, the thickness of the source electrode and the drain electrode is independently selected from any value of ≥20nm.

16. A flexible organic thin-film transistor prepared by the method according to any one of claims 1 to 15, characterized in that, The flexible organic thin-film transistor has a maximum mobility ≥ 4.25 cm⁻¹. 2 V -1 s -1 .

17. The application of the preparation method as described in any one of claims 1 to 15 in the preparation of medical devices, flexible display devices, wearable devices, or the construction of the Internet of Things.

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