An intrinsically low-melting polymer semiconductor material, and a method of making and using the same

Abstract

The application belongs to the technical field of organic semiconductor materials, and particularly relates to an intrinsic low-melting-point polymer semiconductor material and a preparation method and application thereof. The polymer semiconductor material is a pyrrolopyrroloquinoline intrinsic low-melting-point polymer with a macrocyclic crown ether as a side chain. The application reduces the melting point of an existing organic polymer by introducing the macrocyclic crown ether into the side chain. The polymer provided by the application can be used to obtain a high-orientation semiconductor thin film through a melt friction transfer method, and the semiconductor thin film can be used as an organic semiconductor layer in an organic field effect transistor to obtain a new organic field effect transistor. The carrier mobility of the organic field effect transistor is improved by regulating a molecular packing mode. The application provides a feasible method for solvent-free processing of an organic field effect transistor device, which will help to solve the environmental pollution problem caused by traditional solution processing using a chlorinated solvent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic semiconductor materials, and particularly relates to an intrinsically low-melting-point polymer semiconductor material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous acceleration of the informatization degree of today's society, people's demand for intelligent electronic devices has significantly increased. The function implementation and development of these electronic products cannot be separated from the design and research of transistors. Organic field effect transistors with mechanical flexibility, adjustable performance and low manufacturing cost have attracted the interest of many researchers. Conjugated polymers have a delocalized π-electron system, and electrons can move relatively freely on the polymer chain, so they have a high carrier mobility, which can meet the requirements of high mobility and fast switching response of organic field effect transistors. By changing the molecular structure, conjugated length and substituent group of the conjugated polymer, its various performances can be adjusted in a wide range to meet the specific requirements of different application scenarios for organic field effect transistors. Therefore, organic field effect transistors based on conjugated polymers have been considered as the basic elements of optoelectronics, artificial intelligence and wearable devices.

[0003] The semiconductor polymer layer in the organic field effect transistor is usually processed using a solution method. Due to the π-π stacking effect, the intermolecular force of the conjugated polymer is strong, and it usually has a high solubility in a chlorine-containing solvent. However, the chlorine-containing solvent will cause air pollution due to its volatility and persistent organic pollution due to its chemical stability, which will cause serious environmental problems and hinder the industrialization process of organic field effect transistors. Therefore, it is of great significance to develop a more sustainable and green processing strategy for organic field effect transistors based on conjugated polymers. Solvent-free processing has become an effective way to solve this problem, and melt processing has received widespread attention in recent years as a solvent-free technology. However, most high-performance conjugated polymers have a high melting temperature due to their conjugated backbone, which greatly limits the applicability of melt processing in the manufacturing of organic electronic devices. Developing intrinsically low-melting-point high-performance polymer semiconductors is of great significance for the scale production of organic electronics.

[0004] In addition, the charge transport efficiency in the polymer semiconductor thin film should be ensured not to be disturbed while using the melting process. The molecular orientation of the polymer semiconductor has been proved to be the main factor affecting the charge transport in the semiconductor polymer. Studies have shown that regulating the molecular packing structure and the polymer chain arrangement can improve the electrical properties of the conjugated polymer. Various methods have been developed for the orientation of the polymer semiconductor thin film prepared by solution method, such as solution shearing method, eccentric spin coating method, microfluidic system and template printing method, but there are few reports on the combination of melting processing to control the orientation of the polymer thin film. The melting friction transfer technology can regulate the arrangement of the polymer chain by physical means, so that the polymer semi-thin film has high orientation, and the charge transport capacity parallel to the thin film is effectively improved. SUMMARY

[0005] The present application aims at solving the problem that most high-performance conjugated polymers are limited to use the melting process due to their high melting temperature, and provides an intrinsic low-melting-point polymer semiconductor material and a preparation method and application thereof.

[0006] The intrinsic low-melting-point polymer semiconductor material provided by the present application is a macrocyclic crown ether side chain-containing pyrrolopyrroloquinoline conjugated polymer, and the melting point range is 60-140℃, and the structure is shown in the following formula (I):

[0007]

[0008] wherein x and y are the mole numbers of the unit components, and satisfy x:y = 1:50-1:5; n is the polymerization degree; the polymerization degree n = 1-300;

[0009] R1 is a structural formula shown in formula III:

[0010]

[0011] n1 = 1-10;

[0012] R2 is a linear or branched alkyl group with 1-30 carbon atoms;

[0013] AR is one of the following structures, but is not limited to the following structural formula (the same below):

[0014]

[0015] The present application also provides a preparation method of the above-mentioned intrinsic low-melting-point polymer semiconductor material, which is obtained by changing the molar ratio of the polymer with the structure shown in formula (II) and the polymer with the structure shown in formula (IV), and copolymerizing the polymers with the structures shown in formula (II), formula (IV) and formula (V) under Stille coupling reaction to obtain the intrinsic low-melting-point conjugated polymer shown in formula (I).

[0016]

[0017]

[0018] wherein R2 is a linear or branched alkyl group having 1 to 30 carbon atoms;

[0019]

[0020] Further, the present application also provides a preparation method of the intrinsic low-melting polymer film, which adopts a melt friction transfer method, and the specific steps are as follows:

[0021] Step (1) clean the substrate and place it on a constant temperature heating table to heat to a preset temperature.

[0022] Step (2) compress the polymer semiconductor into a block and place it on the substrate heated to the preset temperature, and lightly drag the polymer semiconductor block in a single direction to obtain a melt friction transfer polymer semiconductor film.

[0023] Preferably, the substrate is a pure Si sheet with a low roughness and a smooth surface.

[0024] Preferably, the preset temperature is higher than the melting point of the polymer, and the specific temperature range is 70-180℃.

[0025] The present application also provides an application of the polymer semiconductor film in an organic field effect transistor.

[0026] The present application provides an organic field effect transistor (abbreviated as OFET), which has a high mobility.

[0027] The OFET includes a gate electrode, a dielectric layer, an organic semiconductor layer, a source electrode and a drain electrode, wherein the organic semiconductor layer and the source electrode and the drain electrode are in contact with each other, and the source electrode and the drain electrode form a channel part; the organic semiconductor layer is a polymer semiconductor film obtained by the melt friction transfer method.

[0028] Preferably, the material of the gate electrode is a high-purity N-type phosphorus-doped silicon sheet with a low roughness and a smooth surface.

[0029] Preferably, the electrode material is selected from gold.

[0030] Preferably, the material of the dielectric layer is silicon dioxide, which is a silicon dioxide layer grown on the surface of a high-purity N-type phosphorus-doped silicon sheet, and the thickness is 300 nm.

[0031] Preferably, the channel length-width ratio is 1 / 10.

[0032] The present application also provides a preparation method of the OFET, which includes the following steps:

[0033] Step (1), providing a wafer substrate: the wafer substrate comprises an N-type phosphorus-doped silicon wafer and a surface-grown silicon dioxide layer.

[0034] Step (2), cleaning the wafer substrate in step (1): after etching by piranha etching solution, deionized water and ethanol cleaning in sequence, the wafer substrate is dried by nitrogen.

[0035] Step (3), surface treatment: the cleaned wafer substrate in step (2) is placed in a dry and clean glass dish, a small amount of octadecyltrichlorosilane is added, and vacuum treatment is performed in an oven, and then the wafer substrate is cleaned by n-hexane, chloroform and ethanol in sequence, and dried by nitrogen.

[0036] Step (4), hot evaporation of source-drain electrode: the wafer substrate after surface treatment in step (3) is hot evaporated to obtain a bottom electrode substrate.

[0037] Step (5), obtaining a polymer semiconductor layer by using a melt friction transfer method: the bottom electrode substrate in step (4) is placed on a constant temperature heating table and heated to a preset temperature, and a melt friction transfer polymer semiconductor film is obtained by using the melt friction transfer method.

[0038] Preferably, the source-drain electrode material in step (2) is gold.

[0039] Optionally, the piranha etching solution etching in step (3) can be performed in a manner known to those skilled in the art,

[0040] Preferably, the volume ratio of sulfuric acid and hydrogen peroxide in the piranha etching solution in step (3) is preferably 3:1.

[0041] Preferably, the surface treatment temperature in step (4) is 120℃, and the treatment time is 150-200min.

[0042] Preferably, the preset temperature in step (5) is 70-180℃.

[0043] The intrinsic low-melting-point polymer material provided by the application can be used to process a polymer semiconductor film by using a melt process, which helps to solve the environmental problems that may occur in the solution processing of an organic field effect transistor.

[0044] The preparation method of melt friction transfer adopted by the application can simply and conveniently obtain a continuous large-area polymer semiconductor film, improve the orientation of the polymer film, control the packing mode of the polymer molecules in the film, and greatly improve the charge transport capacity of the polymer semiconductor film.

[0045] The application has the following advantages:

[0046] 1. The intrinsic low-melting-point conjugated polymer provided by the present invention has the following main advantages: (1) The intrinsic low-melting-point polymer semiconductor material can be controlled by adjusting the content of macrocyclic crown ethers in the side chain, thereby realizing the processing of high-performance conjugated polymers using melt processing. (2) The intrinsic low-melting-point polymer semiconductor material still maintains high electrical performance at high temperatures, and organic field-effect transistors based on the intrinsic low-melting-point polymer semiconductor material still have a mobility higher than 1 cm2V-1s-1 at high temperatures.

[0047] 2. The main advantages of the melt-friction transfer preparation method provided by the present invention include: (1) It is a solvent-free processing method, which helps to improve its feasibility in green industrial production. (2) It can control the molecular stacking mode in the melt-friction transfer film, improve the orientation of the polymer semiconductor film, and further improve the charge transport capability of the polymer semiconductor film. (3) The organic field-effect transistor obtained with the melt-friction transfer film as the semiconductor layer has a significantly higher mobility than the organic field-effect transistor obtained by spin coating. Attached Figure Description

[0048] Figure 1 For formula (VI) in Embodiment 1 of the present invention 1 H-NMR spectrum.

[0049] Figure 2 This is the GPC diagram of the polymer described in formula (VI) in Example 1 of the present invention.

[0050] Figure 3 This is a differential scanning calorimetry curve of the polymer described in formula (VI) in Example 1 of the present invention.

[0051] Figure 4 The output characteristic curve of the organic field-effect transistor based on the polymer semiconductor shown in formula (VI) prepared by the melt friction transfer method in Example 1 of the present invention is shown.

[0052] Figure 5 The figure shows the transfer characteristic curve of an organic field-effect transistor based on the polymer semiconductor shown in formula (VI) prepared by the melt-friction transfer method in an example of the present invention.

[0053] Figure 6 For formula (X) in Embodiment 2 of the present invention 1 H-NMR spectrum.

[0054] Figure 7 This is the GPC diagram of the polymer described in formula (X) in Example 1 of the present invention.

[0055] Figure 8 This is a differential scanning calorimetry curve of the polymer described in formula (X) in Example 1 of the present invention.

[0056] Figure 9 Output characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (X) prepared by the melt friction transfer method in Example 1 of the present application.

[0057] Figure 10 Transfer characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (X) prepared by the melt friction transfer method in Example of the present application.

[0058] Figure 11 H-NMR chart of formula (XI) in Example 2 of the present application. 1 H-NMR chart of formula (XI) in Example 2 of the present application.

[0059] Figure 12 GPC chart of the polymer represented by formula (XI) in Example 1 of the present application.

[0060] Figure 13 Differential scanning calorimetry analysis curve chart of the polymer represented by formula (XI) in Example 1 of the present application.

[0061] Figure 14 Output characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (XI) prepared by the melt friction transfer method in Example 1 of the present application.

[0062] Figure 15 Transfer characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (XI) prepared by the melt friction transfer method in Example of the present application. DETAILED DESCRIPTION

[0063] The present application will be further described in the following with reference to the embodiments and the accompanying drawings. The described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0064] Example 1, an intrinsic low-melting conjugated polymer is a pyrrolopyrrolodiketone conjugated polymer with macrocyclic crown ether as side chain, having the structure represented by formula (VI):

[0065]

[0066] wherein, m:n is 1:5; named as: PDPP-2Crown-4T (1:5).

[0067] The color of the intrinsic low-melting conjugated polymer is dark blue;

[0068] In this embodiment, the number average molecular weight and weight average molecular weight of the pyrrolpyrrolodiketone-based (DPP) intrinsic low-melting point conjugated polymer taking the macrocyclic crown ether as the main raw material are 21.9 and 87.0 kDa respectively, the molecular weight distribution PDI is 3.736, and the melting point temperature is 70.15℃. The detailed characterization results are shown in Table 1. Figures 1-3 .

[0069] The preparation method of the PDPP-2Crown-4T includes the following steps:

[0070] (1) Crown-COOH (12.0 g, 30.0 mmol), 3-bromooctanol (18.7 g, 90 mmol) and 4-dimethylaminopyridine (DMAP) (0.976 g, 8.0 mmol) were dissolved in dichloromethane (300 mL) under N2 atmosphere, stirred at 0℃ for 20 min, then EDC (9.2 g, 48.0 mmol) was added to the solution, the reaction mixture was stirred at room temperature for 48 h, filtered, concentrated to obtain a light yellow oil, and then purified by column chromatography (CH2Cl2 / CH3OH, 10:1, v / v) to obtain compound Crown-Octyl (10.2 g, 57.6%).

[0071] The structure of the Crown-Octyl is shown in formula (VII):

[0072]

[0073] (2) DPP (2 g, 4.38 mmol) and anhydrous potassium carbonate (1.8 g, 13.2 mmol) were dissolved in dry N,N-dimethylformamide (DMF, 60 mL) in a three-necked round-bottom flask under N2 atmosphere, the reaction mixture was heated to 120℃ and stirred for 2 h, then Crown-Octyl (5.7 g, 9.6 mmol) dissolved in dry DMF (10 mL) was injected into two portions with a syringe, and the reaction was stirred at 120℃ for 72 h. After cooling to room temperature, the DMF was concentrated under vacuum, then water (100 mL) was added, the solution was extracted with dichloromethane (3×80 mL), dried over anhydrous Na2SO4, and the dichloromethane fraction was concentrated under vacuum. The 2Crown-DPP compound was purified by column chromatography (silica gel, dichloromethane / methanol, 4:1) for three times, and the yield was 1.7%.

[0074] The structure of the compound Crown-DPP is shown in formula (VIII):

[0075]

[0076] (3) Compound DPP (2 g, 4.38 mmol) and anhydrous potassium carbonate (1.8 g, 13.2 mmol) were dissolved in dry N,N-dimethylformamide (DMF, 60 mL) in a three-necked round flask under N2atmosphere, the reaction mixture was heated to 120 °C, stirred for 2 h, then 11-(4-iodobutyl)henryl (4.6 g, 9.6 mmol) dissolved in dry DMF (10 mL) was injected in two portions, the reaction was stirred at 120 °C for 48 h, after cooling to room temperature, the DMF was concentrated in vacuum, then water (100 mL) was added, the solution was extracted with dichloromethane (3 x 80 mL) and dried over anhydrous Na2SO4, the dichloromethane fraction was concentrated in vacuum. Purification by column chromatography (silica gel, hexane / dichloromethane, 5:1) gave compound 2Br-DPP in 76% yield.

[0077] The structure of the compound 2Br-DPP is shown in formula (IX):

[0078]

[0079] (4) Compound 2Br-DPP (180 mg, 0.156 mmol), 2Sn-2Th (74.3 mg, 0.150 mmol), 2Crown-DPP (7.4 mg, 0.005 mmol), Pd2(dba)3(4 mg, 0.03 eq) and P(o-tol)3(5.7 mg, 0.12 eq) were added to a flask rapidly dried with argon, flushed with argon three times. Then 20 mL of dry toluene was added, flushed with argon three times again. Under this condition, the reaction mixture was heated to 120 °C, continuously stirred for 36 h. After cooling to room temperature, the mixture was poured into methanol, the precipitate was filtered. The polymer was purified by Soxhlet extraction with methanol, acetone, hexane to remove oligomers. PDPP-2Crown-4T was extracted with chloroform (1:5), precipitated with methanol, filtered, washed with methanol, and dried at 60 °C in vacuum for 12 h. The final product was obtained as a dark blue solid after purification (165 mg, 89% yield).

[0080] The PDPP-2Crown-4T polymer has a melting point of about 70 °C. As shown in the differential scanning calorimetry curve, a melting peak appears near 70 °C. Figure 3

[0081] The present embodiment also provides the use of the above-mentioned macrocyclic crown ether side chain-containing pyrrolopyrrole diketone low-melting point conjugated polymer as a semiconductor material in electronic devices.

[0082] ​Specifically, an organic field effect transistor comprises an organic semiconductor layer, a source-drain electrode and a gate insulating layer, wherein the organic semiconductor layer is the PDPP-2Crown-4T (1:5) polymer as described in the above technical solution.

[0083] In the present embodiment, the melt friction transfer preparation method comprises the following steps:

[0084] Step 1, clean the substrate and place it on a constant temperature heating table to heat to a preset temperature higher than the melting point of the intrinsic melt polymer semiconductor.

[0085] Step 2, compress the polymer semiconductor into a block and place it on the substrate heated to the preset temperature, and lightly drag the polymer semiconductor block in a single direction to obtain a melt friction transfer polymer semiconductor film.

[0086] The preset temperature higher than the melting point of the intrinsic melt polymer semiconductor is specifically 70-180°C.

[0087] The melt friction transfer preparation method of the organic field effect transistor comprises the following steps:

[0088] Step 1, provide a wafer substrate: the wafer substrate comprises an N-type phosphorus-doped silicon wafer and a surface-grown silicon dioxide layer.

[0089] Step 2, clean the wafer substrate in step 1: sequentially clean with deionized water and ethanol for 15 min each, then dry with nitrogen, and then etch with piranha etchant, clean with deionized water and ethanol for 15 min each, and then dry with nitrogen.

[0090] Photoetching source-drain electrode: photoetch a gold electrode on the wafer substrate as a source-drain electrode, with a channel ratio of 10:1400, to obtain a bottom electrode substrate.

[0091] Step 3, surface treatment: place the cleaned wafer substrate in step (2) in a dry and clean glass dish, drop in a small amount of octadecyltrichlorosilane, and place it in an oven for vacuum treatment, with a treatment temperature of 120°C and a treatment time of 180 min, then sequentially clean with n-hexane, chloroform and ethanol for 15 min each, and then dry with nitrogen.

[0092] Step 4, thermal evaporation of source-drain electrode: thermal evaporation of a source-drain electrode on the surface-treated wafer substrate in step (3) to obtain a bottom electrode substrate.

[0093] Step 5, obtain a polymer semiconductor layer by melt friction transfer method: place the bottom electrode substrate in step (4) on a constant temperature heating table and heat to a preset temperature, with a preset temperature of 140°C, to obtain a melt friction transfer polymer semiconductor film by the melt friction transfer method.

[0094] In the embodiment, the volume ratio of sulfuric acid and hydrogen peroxide in the piranha etching solution is preferably 3:1; the concentration of sulfuric acid in the piranha etching solution is not particularly limited, and a concentration of sulfuric acid known to those skilled in the art can be used. The piranha etching, deionized water washing and acetone washing are not particularly limited, and a process known to those skilled in the art can be used.

[0095] In the embodiment, the mass percentage content of octadecyltrichlorosilane in the toluene solution of octadecyltrichlorosilane is 5%.

[0096] In the embodiment, the surface treatment is preferably carried out under vacuum conditions, the surface treatment temperature is 120°C, and the surface treatment time is 180 min.

[0097] The output characteristics and transfer characteristics of the obtained organic field effect transistor are tested, and the test graphs are shown in Figures 4-5 , wherein, Figure 4 is the output characteristic curve of the organic field effect transistor; Figure 5 is the transfer characteristic curve of the organic field effect transistor.

[0098] From Figures 4-5 It can be seen that the intrinsic low-melting-point conjugated polymer PDPP-2Crown-4T based on macrocyclic crown ether as a side chain shows P-type device characteristics, and the hole mobility is 1.06 cm 2 V -1 s -1 , and the on-off ratio I on / I off is 10 5 .

[0099] The high hole mobility can be attributed to: (1) the intrinsic low-melting-point conjugated polymer based on macrocyclic crown ether as a side chain has the advantages of large π-conjugated system, donor-acceptor system of molecular main chain structure, good intermolecular arrangement and good π-orbital overlap, so that the polymer molecules have excellent aggregation, tight π-π bonding, further improving the transmission speed of carriers (i.e. holes) between and within polymer molecules, thereby promoting the polymer thin film to exhibit good carrier transport performance. (2) The melt friction transfer method makes the polymer thin film have high orientation, improves the order of molecular arrangement in the polymer thin film, and further improves the carrier transport speed.

[0100] In embodiment 2, an intrinsic low-melting-point conjugated polymer is a pyrrolopyrrolidone conjugated polymer with macrocyclic crown ether as a side chain, and has the structure shown in formula (X):

[0101]

[0102] Wherein, m:n is 1:10; named: PDPP-2Crown-4T (1:10).

[0103] The color of the intrinsic low-melting point conjugated polymer is dark blue;

[0104] In this embodiment, the number average molecular weight and weight average molecular weight of the intrinsic low-melting point conjugated polymer of diketopyrrolopyrrole (DPP) based on macrocyclic crown ether as the main raw material are 15.6 and 44.8 kDa, respectively, the molecular weight distribution PDI is 2.863, and the melting point temperature is 70.15 DEG C. The detailed characterization results are shown in Figures 6-8 .

[0105] This embodiment also provides a preparation method of the PDPP-2Crown-4T (1:10), and the preparation method is similar to the synthesis steps of the PDPP-2Crown-4T (1:5) described in Embodiment 1. The yield of the PDPP-2Crown-4T (1:10) is 87%, and the product is a dark blue solid.

[0106] In this embodiment, the PDPP-2Crown-4T (1:10) polymer has a melting point of about 77 degrees. As shown in Figure 8 , the scanning calorimetry curve has a melting peak near 77 DEG C.

[0107] This embodiment also provides the application of the PDPP-2Crown-4T (1:10) polymer as a semiconductor material in electronic devices.

[0108] Specifically provided is an organic field effect transistor, comprising an organic semiconductor layer, a source-drain electrode and a gate insulating layer, and the organic semiconductor layer is the PDPP-2Crown-4T (1:10) polymer according to the above technical solution.

[0109] In this embodiment, the melt friction transfer preparation method of the organic field effect transistor comprises the following steps which are similar to those in Embodiment 1.

[0110] The obtained organic field effect transistor is subjected to output characteristic test and transfer characteristic test, and the test graphs are shown in Figures 9-10 , wherein, Figure 9 is the output characteristic curve of the organic field effect transistor; Figure 10 is the transfer transmission characteristic curve of the organic field effect transistor.

[0111] As shown in Figures 9-10 , the diketopyrrolopyrrole-based intrinsic low-melting point conjugated polymer PDPP-2Crown-4T (1:10) based on macrocyclic crown ether as a side chain exhibits P-type device characteristics, and the hole mobility is 0.83 cm 2 V -1 s-1 , the on-off ratio I on / I off is 10 5 .

[0112] Embodiment 3, an intrinsically low-melting conjugated polymer, is a pyrrolopyrrolodiketone conjugated polymer with macrocyclic crown ether as a side chain, having a structure shown in formula (IX):

[0113]

[0114] wherein m:n is 1:30; named as: PDPP-2Crown-4T (1:30).

[0115] The color of the intrinsically low-melting conjugated polymer is dark blue;

[0116] In this embodiment, the number average molecular weight and weight average molecular weight of the pyrrolopyrrolodiketone-based (DPP) intrinsically low-melting conjugated polymer with macrocyclic crown ether as the main raw material are 14.2 and 53.0 kDa, respectively, the molecular weight distribution PDI is 3.963, and the melting point temperature is 130.65℃. The detailed characterization results are shown in Figures 11-13 .

[0117] This embodiment also provides a preparation method of the PDPP-2Crown-4T (1:30), and the preparation method is similar to the synthesis steps of the PDPP-2Crown-4T (1:5) described in Embodiment 1. The yield of the PDPP-2Crown-4T (1:30) is 85%, and the product is a dark blue solid.

[0118] In this embodiment, the PDPP-2Crown-4T (1:10) polymer has a melting point of about 130℃. As shown in Figure 13 , the differential scanning calorimetry curve shows a melting peak near 130℃.

[0119] This embodiment also provides the application of the above-mentioned PDPP-2Crown-4T (1:30) polymer as a semiconductor material in electronic devices.

[0120] Specifically provided is an organic field effect transistor, comprising an organic semiconductor layer, a source-drain electrode, and a gate insulating layer, wherein the organic semiconductor layer is the PDPP-2Crown-4T (1:30) polymer described in the above technical solution.

[0121] In this embodiment, the melt friction transfer preparation method of the organic field effect transistor comprises the following steps which are similar to those in Embodiment 1.

[0122] The obtained organic field effect transistor is subjected to output characteristic test and transfer characteristic test, and the test graph is shown in Figures 14-15 , wherein,Figure 14 for an organic field effect transistor output characteristic curve; Figure 15 for a transfer transmission characteristic curve of an organic field effect transistor.

[0123] By Figures 14-15 It can be seen that the low-melting-point conjugated polymer PDPP-2Crown-4T (1:30) based on macrocyclic crown ether as a side chain exhibits P-type device characteristics, and the hole mobility is 0.67 cm 2 V -1 s -1 , the on-off ratio I on / I off is 10 5 .

[0124] It should be noted that, for those skilled in the art, a number of improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application. The present application is not limited to the specific technical solutions described in the above embodiments, and any technical solutions formed by equivalent replacement shall fall within the scope of protection of the present application.

Claims

1. An intrinsically low-melting-point polymer, characterized in that, It is a pyrrolopyrrole dione conjugated polymer with macrocyclic crown ethers as side chains, and its melting point range is 60~140℃. Its structure is shown in formula (Ⅰ) below: ， (Ⅰ) Where x and y are the molar numbers of the unit components, satisfying x:y = 1:30 to 1:5; n is the degree of polymerization; the degree of polymerization n = 1 to 300; R1 is the structural formula shown in equation III: ， （Ⅲ） n1=1~10； R2 is a straight-chain or branched alkyl group having 1-30 carbon atoms; AR is one of the following structures: 。 2. The method for preparing the intrinsically low-melting-point polymer as described in claim 1, characterized in that, By changing the molar ratio of the compound with the structure shown in formula (II) and the compound with the structure shown in formula (IV), the intrinsic low-melting-point polymer semiconductor material is obtained by copolymerizing the compounds with the structures shown in formula (II), formula (IV) and formula (V) under Stille coupling reaction. ， （Ⅱ） ， （Ⅳ） Where R2 is a straight-chain or branched alkyl group having 1-30 carbon atoms; , （Ⅴ）。 3. The preparation method according to claim 2, characterized in that, Intrinsic low-melting-point polymer semiconductor thin films were further prepared using the melt-friction transfer method, with the following specific steps: Step (1) Clean the substrate and place it on a constant temperature heating table to heat it to the preset temperature; Step (2) Compress the polymer semiconductor into a block and place it on a substrate that has been heated to a preset temperature. Gently drag the polymer semiconductor block in one direction to obtain a melt-friction transfer polymer semiconductor film. The substrate is a Si wafer with low roughness and a smooth surface; The preset temperature is a temperature higher than the polymer's melting point, specifically 70-180℃.

4. The application of the intrinsically low-melting-point polymer as described in claim 1 in organic field-effect transistors, characterized in that, Polymer semiconductor thin films obtained by melt-friction transfer method are used as organic semiconductor layers in organic field-effect transistors.

5. An organic field-effect transistor, characterized in that, It includes a gate electrode, a dielectric layer, an organic semiconductor layer, a source electrode, and a drain electrode, wherein the organic semiconductor layer and the source electrode are in contact with each other, and a channel portion is formed between the source electrode and the drain electrode; the organic semiconductor layer is a polymer semiconductor thin film obtained by melt friction transfer method from the intrinsic low melting point polymer of claim 1.

6. The organic field-effect transistor according to claim 5, characterized in that: The gate electrode is made of N-type phosphorus-doped silicon wafer with low roughness and a smooth surface; The electrode material is gold; The dielectric layer is made of silicon dioxide, specifically a silicon dioxide layer grown on the surface of an N-type phosphorus-doped silicon wafer, with a thickness of 300 nm. The length-to-width ratio of the channel is 1 / 10.

7. The organic field-effect transistor as described in claim 5 or 6, characterized in that, The specific preparation steps of the polymer semiconductor thin film are as follows: Step (1), providing a wafer substrate: the wafer substrate includes an N-type phosphorus-doped silicon wafer and a silicon dioxide layer grown on its surface; Step (2), cleaning the wafer substrate described in step (1): after being etched by piranha etching solution, cleaned by deionized water and ethanol, it is dried with nitrogen gas; Step (3), surface treatment: Place the cleaned wafer substrate described in step (2) into a dry and clean glass dish, add a small amount of octadecyltrichlorosilane, put it into an oven for vacuum treatment, take it out and clean it with hexane, chloroform and ethanol in sequence, and blow it dry with nitrogen. Step (4), thermally vapor-depositing source and drain electrodes: thermally vapor-depositing source and drain electrodes on the surface-treated wafer substrate described in step (3) to obtain the bottom electrode substrate; Step (5): Obtain a polymer semiconductor layer using the melt friction transfer method: Place the bottom electrode substrate described in step (4) on a constant temperature heating stage and heat it to a preset temperature to obtain a melt friction transfer polymer semiconductor thin film using the melt friction transfer method.

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