Intrinsic low-melting-point polymer semiconductor material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of organic semiconductor materials, and particularly relates to an intrinsic low-melting-point polymer semiconductor material as well as a preparation method and application thereof. The polymer semiconductor material disclosed by the invention is a diketopyrrolopyrrole intrinsic low-melting-point polymer taking macrocyclic crown ether as a side chain. Macrocyclic crown ether is introduced into a side chain, so that the melting point of the existing organic polymer is reduced. The polymer provided by the invention can be used for preparing a high-orientation semiconductor film through a melting friction transfer method, and the semiconductor 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 and controlling a molecular accumulation mode. The invention provides a feasible method for solvent-free processing of organic field effect transistor devices, which is helpful for solving the problem of environmental pollution caused by processing by a traditional solution method using a chlorinated solvent.

Description

Technical Field

[0001] The invention belongs to the technical field of organic semiconductor materials, and in particular relates to an intrinsic low melting point polymer semiconductor material and a preparation method and application thereof. Background Art

[0002] As the degree of informatization in today's society continues to accelerate, people's demand for smart electronic devices has increased significantly. The functional realization and development of these electronic products are inseparable from the design and research of transistors. Organic field-effect transistors with the advantages of 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 that they have a high carrier mobility, which can meet the requirements of organic field-effect transistors for high mobility and fast switching response. By changing the molecular structure, conjugation length, substituents, etc. of conjugated polymers, their various properties can be adjusted in a wide range to meet the specific requirements of organic field-effect transistors in different application scenarios. Therefore, organic field-effect transistors based on conjugated polymers have been considered to be the basic components of optoelectronics, artificial intelligence and wearable devices.

[0003] Semiconducting polymer layers in organic field-effect transistors are usually processed using a solution method. Conjugated polymers usually have high solubility in chlorinated solvents due to their π-π stacking and strong intermolecular forces. However, chlorinated solvents cause atmospheric environmental pollution due to their volatility and persistent organic pollution due to their chemical stability, which will cause serious environmental problems and hinder the industrial production of organic field-effect transistors. Therefore, it is of great significance to develop more sustainable and green processing strategies for organic field-effect transistors based on conjugated polymers. Solvent-free processing has become an effective way to solve this problem, and melt processing as a solvent-free technology has received widespread attention in recent years. However, most high-performance conjugated polymers have a high melting point due to their conjugated skeleton, which greatly limits the applicability of melt processing in the manufacture of organic electronic devices. The development of high-performance polymer semiconductors with intrinsic low melting points is of great significance for the large-scale production of organic electronics.

[0004] In addition, when using the melt process, the charge transfer efficiency in the polymer semiconductor film should not be disturbed. The molecular orientation of polymer semiconductors has been shown to be the main factor affecting charge transport in semiconductor polymers. Studies have shown that regulating the molecular stacking structure and the arrangement of polymer chains can improve the electrical properties of conjugated polymers. A variety of methods have been developed for the oriented preparation of polymer semiconductor films using solution methods, such as solution shearing, eccentric spin coating, microfluidic systems, and template printing. However, there are few reports on controlling the orientation of polymer films by combining melt processing. Melt friction transfer technology can regulate the arrangement of polymer chains by physical means, so that polymer semi-films can obtain a high degree of orientation and effectively improve the charge transfer capacity parallel to the film orientation. Summary of the invention

[0005] The purpose of the present invention is to provide an intrinsic low melting point polymer semiconductor material and a preparation method and application thereof to address the problem that most high performance conjugated polymers are limited in their use in melting processes due to their high melting temperatures.

[0006] The intrinsic low melting point polymer semiconductor material provided by the present invention is a pyrrolopyrrole diketo conjugated polymer with a macrocyclic crown ether as a side chain, with a melting point range of 60 to 140° C. and a structure as shown in the following formula (I):

[0007]

[0008] Wherein, x, y are the molar numbers of the unit components, satisfying x:y=1:50-1:5; n is the degree of polymerization; the degree of polymerization n=1-300;

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

[0010]

[0011] n1=1~10;

[0012] R2 is a straight or branched alkyl group having 1 to 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 invention also provides a method for preparing the above-mentioned intrinsic low melting point polymer semiconductor material, which is to change the molar ratio of the polymer with the structure shown in formula (II) and the polymer with the structure shown in formula (IV), and to obtain the intrinsic low melting point conjugated polymer shown in formula (I) by copolymerizing the polymers with the structures shown in formula (II), formula (IV) and formula (V) under Stille coupling reaction;

[0016]

[0017]

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

[0019]

[0020] Furthermore, the present invention also provides a method for preparing the intrinsic low melting point 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 it to a preset temperature.

[0022] Step (2) compresses the polymer semiconductor into a block, places it on a substrate that has been heated to a preset temperature, and gently drags the polymer semiconductor block in a single direction to obtain a melt-friction-transferred polymer semiconductor film.

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

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

[0025] The invention also provides application of the polymer semiconductor film in organic field effect transistors.

[0026] The present invention provides an organic field effect transistor (abbreviated as OFET) having high mobility.

[0027] The OFET comprises 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 a channel portion is formed between the source electrode and the drain electrode; the organic semiconductor layer is a polymer semiconductor film obtained by the above-mentioned melt friction transfer method.

[0028] Preferably, the gate electrode is made of a high-purity N-type phosphorus-doped silicon wafer with low roughness and 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 wafer and has a thickness of 300 nm.

[0031] Preferably, the channel aspect ratio is 1 / 10.

[0032] The present invention also provides a method for preparing the above OFET, comprising the following steps:

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

[0034] Step (2), cleaning the wafer substrate in step 1: etching with piranha etching solution, cleaning with deionized water and ethanol in sequence, and then drying with nitrogen.

[0035] Step (3), performing surface treatment: placing the cleaned wafer substrate in step (2) into a dry and clean glass dish, dropping a small amount of octadecyltrichlorosilane, placing it in an oven for vacuum treatment, taking it out and washing it with n-hexane, chloroform, and ethanol in sequence, and blowing it dry with nitrogen.

[0036] Step (4), thermal evaporation of source and drain electrodes: thermal evaporation of source and drain electrodes on the wafer substrate after surface treatment in step (3) to obtain a bottom electrode substrate.

[0037] Step (5), obtaining a polymer semiconductor layer by using a melt friction transfer method: placing the bottom electrode substrate described in step (4) on a constant temperature heating table, heating it to a preset temperature, and obtaining a melt friction transfer polymer semiconductor film by 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 carried out in a manner well known to those skilled in the art.

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

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

[0042] Preferably, the preset temperature of step (5) is 70-180°C.

[0043] The intrinsic low melting point polymer material provided by the present invention can be used to process polymer semiconductor films using a melting process, which helps to solve environmental problems that may arise during the solution process of organic field effect transistors.

[0044] The present invention adopts a preparation method of melt friction transfer, which can simply and conveniently obtain a continuous large-area polymer semiconductor film, improve the orientation of the polymer film, regulate the stacking mode of polymer molecules in the film, and greatly improve the charge transfer capacity of the polymer semiconductor film.

[0045] The beneficial effects of the present invention are:

[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 control the melting point of the intrinsic low melting point polymer semiconductor material by controlling the content of the side chain macrocyclic crown ether, thereby realizing high-performance conjugated polymer processing using a melt process. (2) The intrinsic low melting point polymer semiconductor material still maintains high electrical properties at high temperatures, and the organic field effect transistor based on the intrinsic low melting point polymer semiconductor material still has a mobility higher than 1cm2V-1s-1 at high temperatures.

[0047] 2. The melt friction transfer preparation method provided by the present invention has the following main advantages: (1) It is a solvent-free processing method, which helps to improve the feasibility in green industrial production. (2) The molecular stacking pattern in the melt friction transfer film can be regulated to improve the orientation of the polymer semiconductor film and further improve the charge transfer capacity of the polymer semiconductor film. (3) The mobility of the organic field effect transistor obtained with the melt friction transfer film as the semiconductor layer is significantly higher than that of the organic field effect transistor obtained by spin coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the compound of formula (VI) in Example 1 of the present invention 1 H-NMR spectrum.

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

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

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

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

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

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

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

[0056] Fig. 9 This is the 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 invention.

[0057] Fig.10 The transfer characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (X) prepared by melt friction transfer method in an example of the present invention.

[0058] Fig.11 is the compound of formula (XI) in Example 2 of the present invention 1 H-NMR spectrum.

[0059] Fig.12 This is the GPC chart of the polymer of formula (XI) in Example 1 of the present invention.

[0060] Fig.13 This is a differential scanning calorimetry analysis curve of the polymer of formula (XI) in Example 1 of the present invention.

[0061] Fig.14 This is the 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 invention.

[0062] Fig.15 The transfer characteristic curve of the organic field effect transistor based on the polymer semiconductor represented by formula (XI) prepared by melt friction transfer method in an example of the present invention. DETAILED DESCRIPTION

[0063] The present invention is further described below by embodiments in combination with the accompanying drawings according to the specific content of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0064] Example 1, an intrinsic low melting point conjugated polymer, is a pyrrolopyrrole diketo conjugated polymer with a macrocyclic crown ether as a side chain, having a structure shown in formula (VI):

[0065]

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

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

[0068] In this example, the number average molecular weight and weight average molecular weight of the diketopyrrolopyrrole (DPP) intrinsic low melting point conjugated polymer with macrocyclic crown ether as the main raw material are 21.9 and 87.0 kDa, respectively, the molecular weight distribution PDI is 3.736, the melting point temperature is 70.15 ° C, and the detailed characterization results are shown in Figure 1-Figure 3 .

[0069] The preparation method of PDPP-2Crown-4T comprises 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 and stirred at 0°C for 20 min. EDC (9.2 g, 48.0 mmol) was then added to the solution. The reaction mixture was stirred at room temperature for 48 h, filtered and concentrated to obtain a light yellow oil, which was 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 flask under N2 atmosphere. The reaction mixture was heated to 120°C and stirred for 2 h. Crown-Octyl (5.7 g, 9.6 mmol) dissolved in dry DMF (10 mL) was then injected into two portions by syringe. The reaction was stirred at 120°C for 72 h. After cooling to room temperature, DMF was vacuum concentrated. Water (100 mL) was added, and the solution was extracted with dichloromethane (3×80 mL). The solution was dried over anhydrous Na2SO4, and the dichloromethane portion was vacuum concentrated. The 2Crown-DPP compound was purified three times by column chromatography (silica gel, dichloromethane / methanol, 4:1) with a yield of 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 N2 atmosphere. The reaction mixture was heated to 120°C and stirred for 2 h. Then, 11-(4-iodobutyl)henrethane (4.6 g, 9.6 mmol) dissolved in dry DMF (10 mL) was injected into two portions with a syringe. The reaction was stirred at 120°C for 48 h. After cooling to room temperature, DMF was vacuum concentrated, and then water (100 mL) was added. The solution was extracted with dichloromethane (3×80 mL) and dried with anhydrous Na2SO4. The dichloromethane portion was vacuum concentrated. Compound 2Br-DPP was purified by column chromatography (silica gel, hexane / dichloromethane, 5:1) with a yield of 76%.

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

[0078]

[0079] (4) Compounds 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 argon and dried rapidly, and flushed with argon three times. Then 20 mL of dry toluene was added and flushed with argon three times again. Under this condition, the reaction mixture was heated to 120 °C and stirred continuously for 36 h. After cooling to room temperature, the mixture was poured into methanol and the precipitate was filtered. The polymer was purified by Soxhlet extraction with methanol, acetone and hexane as solvents to remove oligomers. PDPP-2Crown-4T was extracted with chloroform (1:5), precipitated with methanol, filtered, washed with methanol, and dried in vacuum at 60 °C for 12 h. The final product was obtained after purification as a dark blue solid (165 mg, yield 89%).

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

[0081] This embodiment also provides the use of the above-mentioned diketopyrrolopyrrole basic low melting point conjugated polymer with macrocyclic crown ether as the side chain 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 described in the above technical solution.

[0083] In this 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 it to a preset temperature higher than the melting point of the intrinsic molten polymer semiconductor.

[0085] Step 2: compress the polymer semiconductor into a block and place it on a substrate that has been heated to a preset temperature, and gently drag the polymer semiconductor block in a single direction to obtain a molten friction transfer polymer semiconductor film.

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

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

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

[0089] Step 2, cleaning the wafer substrate described in step 1: cleaning it with deionized water and ethanol for 15 minutes each, blowing it dry with nitrogen, etching it with piranha etching solution, cleaning it with deionized water and ethanol for 15 minutes each, and blowing it dry with nitrogen.

[0090] Photolithography of source and drain electrodes: Photolithography of gold electrodes as source and drain electrodes on the wafer substrate 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) into a dry and clean glass dish, drop a small amount of octadecyltrichlorosilane into it, place it in an oven for vacuum treatment at a temperature of 120°C for 180 min, take it out and wash it with n-hexane, chloroform and ethanol in sequence for 15 min, and blow it dry with nitrogen.

[0092] Step 4, thermally evaporating source and drain electrodes: thermally evaporating source and drain electrodes on the wafer substrate after the surface treatment in step (3) to obtain a bottom electrode substrate.

[0093] Step 5, obtaining a polymer semiconductor layer by using a melt friction transfer method: placing the bottom electrode substrate described in step (4) on a constant temperature heating table, heating it to a preset temperature, the preset temperature is 140°C, and obtaining a melt friction transfer polymer semiconductor film by the melt friction transfer method.

[0094] In this embodiment, the volume ratio of sulfuric acid to hydrogen peroxide in the piranha etching solution is preferably 3:1; there is no special limitation on the concentration of sulfuric acid in the piranha etching solution, and a sulfuric acid concentration well known to those skilled in the art can be used. There is no special limitation on the piranha etching solution etching, deionized water washing and acetone washing, and processes well known to those skilled in the art can be used.

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

[0096] In this embodiment, the surface treatment is preferably performed 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. The test diagram is shown in Figures 4-5 ,in, Figure 4 is the output characteristic curve of the organic field effect transistor; Figure 5 It is the transfer characteristic curve of organic field effect transistor.

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

[0099] The high hole mobility can be attributed to the following: (1) The intrinsic low melting point conjugated polymers based on pyrrolopyrrole diketopolymers with macrocyclic crown ether as side chains have the advantages of large π-conjugated system, donor-acceptor system of molecular main chain structure, good molecular arrangement and good π-orbital overlap, which make the polymer molecules have excellent aggregation and tight π-π bonding, further improving the transfer speed of carriers (i.e. holes) between polymer molecules and within molecules, thus promoting the polymer film to exhibit good carrier mobility performance. (2) The melt friction transfer preparation method makes the polymer film highly oriented, improves the orderliness of molecular arrangement in the polymer film, and further improves the carrier transfer speed.

[0100] Example 2, an intrinsic low melting point conjugated polymer, is a pyrrolopyrrole diketo conjugated polymer with a macrocyclic crown ether as a side chain, having a structure shown in formula (X):

[0101]

[0102] Among them, 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 example, the number average molecular weight and weight average molecular weight of the diketopyrrolopyrrole (DPP) intrinsic low melting point conjugated polymer with 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°C. Detailed characterization results are shown in Figure 6-Figure 8 .

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

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

[0107] This embodiment also provides the use of the PDPP-2Crown-4T (1:10) polymer as a semiconductor material in an electronic device as described in the above technical solution.

[0108] 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 (1:10) polymer described in the above technical solution.

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

[0110] The output characteristics and transfer characteristics of the obtained organic field effect transistor are tested. The test diagram is shown in Figures 9-10 ,in, Fig. 9 is the output characteristic curve of the organic field effect transistor; Fig.10 It is the transfer characteristic curve of organic field effect transistor.

[0111] Depend on Figures 9-10 It can be seen that the intrinsic low melting point conjugated polymer PDPP-2Crown-4T (1:10) based on pyrrolopyrrole diketoside with macrocyclic crown ether as the side chain exhibits P-type device characteristics with a hole mobility of 0.83 cm 2 V -1 s-1 , the switching ratio I on / I off For 10 5 .

[0112] Example 3, an intrinsic low melting point conjugated polymer, is a pyrrolopyrrole diketo conjugated polymer with a macrocyclic crown ether as a side chain, having a structure shown in formula (XI):

[0113]

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

[0115] The color of the intrinsic low melting point conjugated polymer is dark blue;

[0116] In this example, the number average molecular weight and weight average molecular weight of the diketopyrrolopyrrole (DPP) intrinsic low melting point 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°C. Detailed characterization results are shown in Figure 11-13 .

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

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

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

[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 includes the following steps similar to those in Embodiment 1.

[0122] The output characteristics and transfer characteristics of the obtained organic field effect transistor are tested. The test diagram is shown in Figures 14-15 ,in, Fig.14 is the output characteristic curve of the organic field effect transistor; Fig.15 It is the transfer characteristic curve of organic field effect transistor.

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

[0124] It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement belong to the protection scope of the present invention.

Claims

1. An intrinsic low melting point polymer, characterized in that It is a pyrrolopyrrole diketo conjugated polymer with a macrocyclic crown ether as a side chain, with a melting point range of 60 to 140°C and a structure as shown in the following formula (I): Wherein, x, y are the molar numbers of the unit components, satisfying x:y=1:30-1:5; n is the degree of polymerization; the degree of polymerization n=1-300; R1 is the structural formula shown in formula III: n1＝1～10； R2 is a straight or branched alkyl group having 1 to 30 carbon atoms; AR is one of the following structures:

2. The method for preparing an intrinsic low melting point polymer according to claim 1, characterized in that: The intrinsic low melting point polymer semiconductor material is obtained by copolymerizing the polymers of the structures represented by formula (II), formula (IV) and formula (V) under Stille coupling reaction by changing the molar ratio of the polymer of the structure represented by formula (II) and the polymer of the structure represented by formula (IV); Wherein R2 is a straight or branched alkyl group having 1 to 30 carbon atoms; 3. The preparation method according to claim 2, characterized in that: The intrinsic low melting point polymer film is further prepared by melt friction transfer method, and the specific steps are as follows: Step (1) clean the substrate and place it on a constant temperature heating table and heat it to a preset temperature; Step (2) compressing the polymer semiconductor into a block, placing it on a substrate heated to a preset temperature, and gently dragging the polymer semiconductor block in a single direction to obtain a melt friction transfer polymer semiconductor film; The substrate is a pure Si sheet with low roughness and smooth surface; The preset temperature is a temperature higher than the melting point of the polymer, specifically 70-180°C.

4. The use of the intrinsic low melting point polymer in an organic field effect transistor as claimed in claim 1, characterized in that: The polymer semiconductor film obtained by melt friction transfer method is used as the organic semiconductor layer in the organic field effect transistor.

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 and the drain 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 film obtained by a melt friction transfer method.

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

7. The method for preparing an organic field effect transistor according to claim 5 or 6, characterized in that: The specific steps are: Step (1), providing a wafer substrate: the wafer substrate comprises an N-type phosphorus-doped silicon wafer and a silicon dioxide layer grown on the surface; Step (2), cleaning the wafer substrate in step (1): etching with piranha etching solution, cleaning with deionized water and ethanol, and then drying with nitrogen gas Step (3), performing surface treatment: placing the cleaned wafer substrate in step (2) into a dry and clean glass dish, dropping a small amount of octadecyltrichlorosilane, placing the wafer substrate in an oven for vacuum treatment, taking the wafer substrate out and washing it with n-hexane, chloroform, and ethanol in sequence, and drying it with nitrogen; Step (4), thermally evaporating source and drain electrodes: thermally evaporating source and drain electrodes on the wafer substrate after the surface treatment in step (3) to obtain a bottom electrode substrate; Step (5), obtaining a polymer semiconductor layer by using a melt friction transfer method: placing the bottom electrode substrate described in step (4) on a constant temperature heating table, heating it to a preset temperature, and obtaining a melt friction transfer polymer semiconductor film by the melt friction transfer method.

Images