Polymer containing bipyridinopyrazine diindene heterocyclic unit and preparation method and application thereof

Abstract

The invention belongs to the field of polymer semiconductor materials, and discloses a polymer containing a bipyridinopyrazine diindene heterocyclic unit and a preparation method and application thereof. The chemical structural formula of the polymer containing the bispyridinopyrazine diindene heterocyclic ring unit is shown as a formula I or a formula II. The preparation method of the polymer containing the bispyridinopyrazine diindene heterocyclic unit has the advantages of being high in synthesis method universality, mild in synthesis condition, high in synthesis yield and the like, and can be popularized and applied to amplified synthesis and production in the industry. A thin film field effect transistor prepared by taking the polymer semiconductor containing the bipyridinopyrazine diindene heterocyclic ring unit as an active layer, which is reported by the invention, shows an excellent electron transmission characteristic; the polymer semiconductor material has wide market prospects in p-n junctions, organic thermoelectricity, complementary logic circuits, organic solar cells, field effect transistors and other organic electronic devices. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of polymer semiconductor materials, and particularly relates to a class of polymers containing bipyridino[3,2-b:2',3'-d]pyrazine-fused indacene heterocyclic units, and their preparation methods and applications. Background Art

[0002] As a core material in the field of organic electronics, electron-transporting polymer semiconductor materials (n-type polymer semiconductor materials) have broad market prospects in organic electronic devices such as p-n junctions, organic thermoelectrics, complementary logic circuits, organic solar cells, and field-effect transistors due to their solution processability, excellent flexibility and machinability, and the ability to regulate the material structure through chemical modification. Currently, such materials still face challenges such as low mobility, poor stability, and unclear carrier transport mechanisms.

[0003] From the perspective of the chemical structure design of n-type polymer semiconductor materials, the transport properties of the materials are mainly determined by electron-deficient building units (Adv. Mater. 2017, 29, 1606217; Chem. Soc. Rev. 2023, 52, 1331). Currently, the electron-deficient building units available for n-type polymer semiconductors mainly focus on: imide-based building units, amide-based building units, B←N bond-containing building units, and cyano-functionalized building units. From the above building units, the electron-deficient building units available for n-type polymer semiconductors still show scarcity. Therefore, further design and development of new electron-deficient building units and their conjugated polymers are still effective ways to address these challenges. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages and deficiencies of the prior art, the primary object of the present invention is to provide a class of polymers containing bipyridino[3,2-b:2',3'-d]pyrazine-fused indacene heterocyclic units.

[0005] Another object of the present invention is to provide a preparation method for the above polymers containing bipyridino[3,2-b:2',3'-d]pyrazine-fused indacene heterocyclic units.

[0006] Another object of the present invention is to provide the application of the above polymers containing bipyridino[3,2-b:2',3'-d]pyrazine-fused indacene heterocyclic units in the preparation of organic field-effect transistor devices.

[0007] The objects of the present invention are achieved by the following solutions:

[0008] A class of polymers containing bipyridino[3,2-b:2',3'-d]pyrazine-fused indacene heterocyclic units, the chemical structural formula of which is shown in Formula I or Formula II:

[0009]

[0010] In Formula I and Formula II, R is a straight-chain alkyl group with 6 to 16 carbon atoms or a branched-chain alkyl group with 8 to 30 carbon atoms;

[0011] Ar is one of the structures shown below, but not limited to the following structural formulas, where the definition of R in Ar is the same as the definition of R in Formula I and Formula II;

[0012]

[0013] n is an integer from 10 to 300.

[0014] The straight-chain alkyl group with 6 to 16 carbon atoms is one of n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl or n-hexadecyl.

[0015] The branched-chain alkyl group with 8 to 30 carbon atoms is one of 2-ethylhexyl, 2-butylhexyl, 2-hexyloctyl, 4-hexyldecyl, 3-hexylundecyl, 2-octyldecyl, 2-octyldodecyl, 3-octyltridecyl, 2-decyldodecyl, 2-decyltetradecyl, 3-decylpentadecyl, 2-dodecylhexadecyl, 4-octyltetradecyl, 4-decylhexadecyl, 4-octyldodecyl, 4-decyltetradecyl or 4-dodecylhexadecyl.

[0016] The polymer containing a bipyridino[2,3-f]pyrazino[2,3-h]indene heterocyclic unit has a chemical structural formula as shown in PBPTVT1:

[0017]

[0018] where n is an integer from 10 to 300.

[0019] The polymer containing a bipyridino[2,3-f]pyrazino[2,3-h]indene heterocyclic unit has a chemical structural formula as shown in PBPTVT2:

[0020]

[0021] where n is an integer from 10 to 300.

[0022] A method for preparing the polymer containing a bipyridino[2,3-f]pyrazino[2,3-h]indene heterocyclic unit includes the following steps:

[0023] S1. Mix 2-tributylstannyl- 4-alkylthiophene with 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine and carry out a palladium-catalyzed Stille coupling reaction to obtain intermediate a;

[0024] S2. Selectively reduce the intermediate a with zinc powder to obtain intermediate b;

[0025] S3. Condense the intermediate b with ninhydrin to obtain intermediate c or intermediate d respectively;

[0026] S4. Mix the intermediate c or intermediate d with hexabutylditin respectively and carry out palladium-catalyzed Stille coupling reaction to obtain intermediate e and intermediate f respectively;

[0027] S5. Carry out nucleophilic substitution reaction on the intermediate e and intermediate f respectively under the action of malononitrile to obtain intermediate g and intermediate h respectively;

[0028] S6. Carry out electrophilic substitution reaction to introduce bromine on the intermediate g or intermediate h and N-bromosuccinimide respectively to obtain compound M 1 and compound M 2 ;

[0029] S7. Carry out Stille coupling condensation reaction on the compound M 1 or compound M 2 and bis(trimethylstannyl) substituted aromatic heterocyclic monomer g under the action of a palladium catalyst to obtain polymers containing bipyridino[2,3-f][1,5]naphthyridino[2,3-f]indene heterocyclic units with the structural formulas of Formula I and Formula II respectively;

[0030] Among them, the structural formula of the intermediate a is:

[0031]

[0032] The structural formula of the intermediate b is:

[0033]

[0034] The structural formula of the intermediate c is:

[0035]

[0036] The structural formula of the intermediate d is:

[0037]

[0038] The structural formula of the intermediate e is:

[0039]

[0040] The structural formula of the intermediate f is:

[0041]

[0042] The structural formula of the intermediate g is:

[0043]

[0044] The structural formula of the intermediate h is as follows:

[0045]

[0046] The compound M 1 has the structural formula as follows:

[0047]

[0048] The compound M 2 has the structural formula as follows:

[0049]

[0050] The structural formula of the bis(trimethylstannyl)-substituted aromatic heterocyclic monomer i is as follows:

[0051]

[0052] Wherein, R is a straight-chain alkyl group with 6 to 16 carbon atoms or a branched-chain alkyl group with 8 to 30 carbon atoms; Ar is one of the following structures, and the definition of R in Ar is the same as that of R in Formula I and Formula II;

[0053]

[0054] The n is an integer from 10 to 300.

[0055] The method for preparing a polymer containing a bipyridino[3,4-f]pyridazine[1,2-a]indene heterocyclic unit specifically includes the following steps:

[0056] S1. Under nitrogen protection, 2-tributylstannyl-4-alkylthiophene, 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine, a palladium catalyst and a solvent are mixed and refluxed with stirring for 3 to 10 hours to obtain intermediate a; the molar ratio of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine, 2-tributylstannyl-4-alkylthiophene to the palladium catalyst is 1.0:1.0 to 3.0:0.01 to 0.1;

[0057] S2. Under nitrogen protection, intermediate a, reduced zinc powder and a solvent are mixed and refluxed with stirring for 3 to 10 hours to obtain intermediate b; the molar ratio of intermediate a to zinc powder is 1.0:3.0 to 10.0;

[0058] S3. Intermediate b and ninhydrin are added to a solvent and refluxed with stirring for 1 to 3 hours to obtain intermediate c and intermediate d respectively; the molar ratio of ninhydrin to intermediate a described in step S2 is 3.0 to 10.0:1.0;

[0059] S4. Under nitrogen protection, mix the intermediate c or intermediate d, hexabutylditin, a palladium catalyst, and a solvent, and reflux and stir for 3 to 10 hours to obtain intermediate e or intermediate f respectively; the molar ratio of the intermediate c or intermediate d, hexabutylditin to the palladium catalyst is 1.0:0.5 - 1:0.01 - 0.1;

[0060] S5. Under nitrogen protection, sequentially add intermediate e or intermediate f, malononitrile, dichloromethane, and pyridine to a three-necked flask, and finally slowly add titanium tetrachloride, and stir and react at 40 °C for 10 to 20 hours to obtain intermediate g and intermediate h respectively; the dosage ratio of the intermediate e or intermediate f, pyridine, and malononitrile is 1.0 mmol:4.0 - 10.0 mmol:1.0 - 2.0 mL;

[0061] S6. Under nitrogen protection, mix intermediate g or intermediate h with a solvent; then add N-bromosuccinimide to the mixture, and stir and react at room temperature for 5 to 10 hours to obtain compound M 1 and compound M 2 ; the molar ratio of the intermediate g or intermediate h to N-bromosuccinimide is 1:2.0 - 3.0;

[0062] S7. Mix the compound M 1 or compound M 2 , a bis(trimethyltin)-substituted aromatic heterocyclic monomer i, a solvent, and a palladium catalyst, and stir and react at 80 °C to 150 °C under nitrogen protection for 24 to 72 hours to obtain a polymer containing a bipyridino[3,2-a]pyrazino[2,3-f]indeno[1,2-b]indene heterocyclic unit; the molar ratio of the compound M 1 or M 2 , the bis(trimethyltin)-substituted aromatic heterocyclic monomer i to the palladium catalyst is 1:1.0 - 1.5:0.01 - 0.1.

[0063] The palladium catalyst is one or more of tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride, and tris(dibenzylideneacetone)dipalladium.

[0064] The solvent is one or more of toluene, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, chlorobenzene, dichlorobenzene, trichlorobenzene, and tetrahydrofuran.

[0065] Application of the polymer containing a bipyridino[3,2-a]pyrazino[2,3-f]indeno[1,2-b]indene heterocyclic unit in the preparation of an organic field effect transistor device.

[0066] The present invention has the following advantages and beneficial effects compared with the prior art:

[0067] (1) The preparation method of the polymer containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit provided by the present invention has the advantages of strong universality of the synthesis method, mild synthesis conditions, high synthesis yield, etc., and can be popularized and applied to the scale-up synthesis and production in industry.

[0068] (2) The polymer material containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit provided by the present invention has a large π-conjugated skeleton with heteroatoms, which can enhance the intra- and intermolecular π-π interactions and improve the carrier mobility.

[0069] (3) For the polymer material containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit provided by the present invention, due to the introduction of an electron-deficient acceptor unit, this type of material has a relatively low LUMO energy level.

[0070] (4) The polymer material containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit provided by the present invention has broad commercial prospects in organic electronics fields such as organic field-effect transistors.

[0071] (5) The polymer material containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit provided by the present invention, as the active layer of an organic field-effect transistor device, exhibits excellent electron transport characteristics, and its highest electron mobility is 0.035 cm 2 / V s, fully demonstrating that this type of polymer semiconductor material has broad market prospects in organic electronic devices such as p-n junctions, organic thermoelectrics, complementary logic circuits, organic solar cells, and field-effect transistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 Absorption spectra of the solid films formed on quartz wafers of the polymer materials PBPTVT1 and PBPTVT2 containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit obtained in Example 1 and Example 2, respectively.

[0073] Figure 2 Schematic diagrams of the structures of organic field-effect transistor devices using the polymer materials PBPTVT1 and PBPTVT2 containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit obtained in Example 1 and Example 2 as the organic active layer, respectively.

[0074] Figure 3 Transfer characteristic curve of the organic field-effect transistor device using the polymer material PBPTVT1 containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit obtained in Example 1 as the organic active semiconductor layer.

[0075] Figure 4 Output characteristic curve of the organic field-effect transistor device using the polymer material PBPTVT1 containing a bipyridino[3,2-b]pyrazino[2,3-f]indenyl heterocyclic unit obtained in Example 1 as the organic active semiconductor layer.

[0076] Figure 5 Transfer characteristic curve of an organic field effect transistor device with the polymer material PBPTVT2 containing a bipyridino[3,2-b]pyrazino[2,3-f]indeno[1,2-b]indene heterocyclic unit obtained in Example 2 as the organic active semiconductor layer.

[0077] Figure 6 Output characteristic curve of an organic field effect transistor device with the polymer material PBPTVT2 containing a bipyridino[3,2-b]pyrazino[2,3-f]indeno[1,2-b]indene heterocyclic unit obtained in Example 2 as the organic active semiconductor layer. Detailed implementation mode

[0078] The present invention will be further described in detail below in conjunction with examples and drawings, but the implementation modes of the present invention are not limited thereto. For those not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0079] Reagents used in the examples can be conventionally purchased from the market without special instructions.

[0080] Example 1

[0081] A polymer PBPTVT1 of the present invention containing a bipyridino[3,2-b]pyrazino[2,3-f]indeno[1,2-b]indene heterocyclic unit, and the PBPTVT1 has a structural general formula of Formula I:

[0082]

[0083] Among them, R is n-dodecyl, and Ar is

[0084] The specific structural formula of PBPTVT1 is:

[0085]

[0086] The synthesis route of PBPTVT1 is:

[0087]

[0088] Specifically, it includes the following steps:

[0089] (1) Synthesis of intermediate a: Under nitrogen protection, tributyl(4-dodecylthiophen-2-yl)stannane was added to a three-necked flask (7.12 mmol), 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (6.78 mmol), bis(triphenylphosphine)palladium dichloride (0.34 mmol) and 50 mL of toluene solvent. After refluxing and stirring the reaction for 3 hours, it was cooled to room temperature. The organic phase was extracted with dichloromethane and saturated brine, dried over anhydrous magnesium sulfate, and the solvent was evaporated to obtain the crude product. Purification was carried out using a silica gel column chromatography (eluent: petroleum ether:dichloromethane = 5:1, V:V) to obtain a red solid, namely intermediate a (yield = 82%).

[0090] The structural characterization data of intermediate a are as follows:

[0091] MALDI-TOF-MS: m / z [M] + calcd for (C 21 H 28 BrN 3 S 2 ): 467.09; found: 467.13.

[0092] As can be seen from the above, the structure of this compound is correct and it is the indicated intermediate a.

[0093] (2) Synthesis of intermediate c: Under nitrogen protection, intermediate a (4.29 mmol), reduced zinc powder (21.44 mmol) and 30 mL of acetic acid solvent were added to a three-necked flask. After refluxing and stirring the reaction for 5 hours, it was cooled to room temperature. The excess zinc powder was filtered off, and the organic phase was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and the solvent was evaporated to obtain the amine compound intermediate b. Then, the obtained amine intermediate b and ninhydrin (17.10 mmol) were added to a three-necked flask containing 30 mL of ethanol solution for reaction. After refluxing and stirring the reaction for 12 hours, it was cooled to room temperature. Extraction was carried out with dichloromethane, dried over anhydrous magnesium sulfate, the solvent was evaporated under reduced pressure, and purification was carried out using a silica gel column chromatography (eluent: petroleum ether:dichloromethane = 4:1, V:V) to obtain two products that are isomers of each other. The first eluted product of the first segment was collected to obtain a dark red solid, namely intermediate c (yield = 48%).

[0094] The structural characterization data of intermediate c are as follows:

[0095] 1 H NMR (400 MHz, CDCl 3 ), δ (ppm): 8.73 (s, 1H), 8.55 (d, 1H), 8.52 (d, 1H), 7.84 (t, 2H), 7.75 (t, 2H), 7.49 (s, 1H), 6.83 (s, 1H), 2.65 (t, 2H), 1.33 - 1.28 (m, 20H), 0.88 - 0.85 (t, 3H);

[0096] HRMS (MALDI-TOF): m / z [M] + calcd for (C 30 H 32 BrN 4 OS): 563.14; found: 562.69。

[0097] As can be seen from the above, the structure of this compound is correct and it is the intermediate c as shown.

[0098] (3) Synthesis of intermediate e: Under nitrogen protection, intermediate c (3.56 mmol), hexabutylditin (1.78 mmol), bis(triphenylphosphine)palladium dichloride (0.18 mmol) and 50 mL of toluene solvent were successively added to a three-necked flask. After refluxing and stirring for 3 hours, it was cooled to room temperature. The organic phase was extracted with dichloromethane and saturated brine, dried over anhydrous magnesium sulfate, and the solvent was evaporated to dryness to obtain a crude product, which was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 2:1, V︰V) to obtain a purple-red solid, which is intermediate e (yield = 82%).

[0099] The structure characterization data of intermediate e are as follows:

[0100] HRMS (MALDI-TOF): m / z [M] + calcd for (C 60 H 64 N 6 O 2 S 2 ): 965.33; found: 965.46。

[0101] As can be seen from the above, the structure of this compound is correct and it is the intermediate e as shown.

[0102] (4) Synthesis of intermediate g: Under nitrogen protection, intermediate e (2.07 mmol), malononitrile (10.36 mmol), 50 mL of dichloromethane and 3 mL of pyridine were successively added to a three-necked flask, and finally 0.5 mL of titanium tetrachloride was slowly added. After stirring at 40 °C for 15 hours, it was cooled to room temperature. It was extracted with dichloromethane and saturated brine, the organic phase was dried over anhydrous magnesium sulfate, the solvent was evaporated under reduced pressure, and the obtained crude product was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 1:1, V︰V) to obtain a brown solid, which is intermediate g (yield = 75%).

[0103] The structure characterization data of intermediate g are as follows:

[0104] HRMS (MALDI-TOF): m / z [M] + calcd for (C 66 H 64 N10 S 2 ): 1061.43; found: 1061.52.

[0105] As can be seen from the above, the structure of this compound is correct and it is the intermediate e shown.

[0106] (5) Synthesis of compound M 1 Under nitrogen protection, intermediate g (1.88 mmol) was added to a three-necked flask containing chloroform and N,N'-dimethylformamide, and it was stirred in an ice bath. Then, N-bromosuccinimide (4.71 mmol) was dissolved in 5 mL of N,N'-dimethylformamide to obtain a mixed solution, and the above mixed solution was slowly added dropwise to the reaction solution using a syringe. After stirring the reaction at room temperature for 12 hours, it was extracted with dichloromethane, dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The obtained crude product was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 2:1, V:V) to obtain a brown solid, which is the monomer compound M 1 (Yield = 83%).

[0107] Compound M 1 The structure characterization data are as follows,

[0108] HRMS (MALDI-TOF): m / z [M] + calcd for (C 60 H 62 Br 2 N 6 O 2 S 2 ): 1123.12; found: 1123.26.

[0109] As can be seen from the above, the structure of this compound is correct and it is the compound M shown. 1 .

[0110] (6) Synthesis of polymer PBPTVT1: Monomer compound M 1 (0.44 mmol), (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethylene (0.44 mmol), 6 mg of tetrakis(triphenylphosphine)palladium and 3 mL of chlorobenzene were deoxygenated by three freeze-pump-thaw cycles in argon. Under nitrogen protection, after stirring the reaction at 115 °C for 72 h, it was cooled to room temperature. 200 mL of methanol was added, and it was stirred at room temperature for 0.5 h, then filtered. The obtained polymer was loaded into a Soxhlet extractor for extraction. It was extracted successively with methanol, acetone, and petroleum ether until colorless to remove small molecules and catalysts, and then extracted with chloroform. The chloroform was evaporated to obtain a black solid with a metallic luster, namely PBPTVT1 (yield = 93%).

[0111] The molecular weight and its molecular weight distribution are as follows: the weight-average molecular weight M w is 26.9 kDa, and the number-average molecular weight M n is 15.1 kDa, and the polymer molecular weight distribution index is 1.78.

[0112] Example 2:

[0113] A polymer PBPTVT2 containing a bipyridino[1,2-a:2',1'-c]pyrazino[2,3-f]indene heterocyclic unit of the present invention, and the PBPTVT2 has a general structural formula of Formula II:

[0114]

[0115] Wherein, R is n-dodecyl, and Ar is

[0116] The specific structural formula of PBPTVT2 is:

[0117] The synthesis route of PBPTVT2 is:

[0118]

[0119] Specifically, it includes the following steps:

[0120] (1) Synthesis of intermediate a: Synthesized with reference to the synthesis method of Example 1 above.

[0121] (2) Synthesis of intermediate d: Under nitrogen protection, add intermediate a (1.65 mmol), reduced zinc powder (8.25 mmol) and 30 mL of acetic acid solvent to a three-necked flask. After refluxing and stirring for 5 hours, cool to room temperature. Filter off the excess zinc powder, extract the organic phase with ethyl acetate, dry with anhydrous magnesium sulfate, and rotary evaporate the solvent to obtain the amine compound intermediate b. Then, add the obtained amine intermediate b and ninhydrin (6.22 mmol) to a three-necked flask containing 20 mL of ethanol solution for reaction. After refluxing and stirring for 12 hours, cool to room temperature. Extract with dichloromethane, dry with anhydrous magnesium sulfate, rotary evaporate the solvent under reduced pressure, and purify by silica gel chromatography column (the eluent is petroleum ether:dichloromethane = 4:1, V:V) to obtain two products that are isomers of each other. Collect the second product eluted later to obtain a dark red solid, namely intermediate d (yield = 42%).

[0122] The structural characterization data of intermediate d are as follows:

[0123] 1 H NMR (400 MHz, CDCl 3), δ(ppm): 8.71 (s, 1H), 8.52 (d, 1H), 8.49 (d, 1H), 7.82 (t, 2H), 7.71 (t, 2H), 7.52 (s, 1H), 6.74 (s, 1H), 2.68 (t, 2H), 1.33 - 1.25 (m, 20H), 0.87 - 0.85 (t, 3H);

[0124] HRMS (MALDI - TOF): m / z [M] + calcd for (C 30 H 32 BrN 4 OS): 563.14; found: 562.89.

[0125] As can be seen from the above, the structure of this compound is correct and it is the intermediate d as shown.

[0126] (3) Synthesis of intermediate f: Under nitrogen protection, intermediate d (3.56 mmol), hexabutylditin (1.78 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.18 mmol) and 50 mL of toluene solvent were successively added to a three - necked flask. After refluxing and stirring for 3 hours, it was cooled to room temperature. The organic phase was extracted with dichloromethane and saturated brine, dried over anhydrous magnesium sulfate, and the solvent was evaporated to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 2:1, V︰V) to obtain a purple - red solid, which is intermediate e (yield = 76%).

[0127] The structure characterization data of intermediate e are as follows:

[0128] HRMS (MALDI - TOF): m / z [M] + calcd for (C 60 H 64 N 6 O 2 S 2 ): 965.33; found: 965.12.

[0129] As can be seen from the above, the structure of this compound is correct and it is the intermediate f as shown.

[0130] (4) Synthesis of intermediate h: Under nitrogen protection, to a three-necked flask were successively added intermediate h (2.07 mmol), malononitrile (10.36 mmol), 50 mL of dichloromethane and 3 mL of pyridine, and finally 0.5 mL of titanium tetrachloride was slowly added. After stirring at 40 °C for 15 hours, it was cooled to room temperature. It was extracted with dichloromethane and saturated brine, the organic phase was dried with anhydrous magnesium sulfate, the solvent was rotary evaporated under reduced pressure, and the obtained crude product was purified by silica gel column chromatography (the eluent was petroleum ether:dichloromethane = 1:1, V︰V) to obtain a brown solid, which was intermediate h (yield = 79%).

[0131] The structural characterization data of intermediate h are as follows:

[0132] HRMS (MALDI-TOF): m / z [M] + calcd for (C 66 H 64 N 10 S 2 ): 1061.43; found: 1061.11.

[0133] As can be seen from the above, the structure of this compound is correct and it is the intermediate h as shown.

[0134] (5) Synthesis of compound M 2 : Under nitrogen protection, intermediate h (1.88 mmol) was added to a three-necked flask containing chloroform and N,N′-dimethylformamide, and it was stirred in an ice bath. Then, N-bromosuccinimide (4.71 mmol) was dissolved in 5 mL of N,N′-dimethylformamide to obtain a mixed solution, and the above mixed solution was slowly added dropwise to the reaction solution using a syringe. After stirring at room temperature for 12 hours, it was extracted with dichloromethane, dried with anhydrous magnesium sulfate, and the solvent was rotary evaporated under reduced pressure. The obtained crude product was purified by silica gel column chromatography (the eluent was petroleum ether:dichloromethane = 2:1, V︰V) to obtain a brown solid, which was monomer compound M 2 (yield = 86%).

[0135] The structural characterization data of compound M 2 are as follows,

[0136] HRMS (MALDI-TOF): m / z [M] + calcd for (C 60 H 62 Br 2 N 6 O 2 S 2 ): 1123.12; found: 1123.56.

[0137] As can be seen from the above, the structure of this compound is correct and it is the compound M as shown2 .

[0138] (6) Synthesis of polymer PBPTVT2: Monomer compound M 2 (0.5 mmol), (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethylene (0.5 mmol), 6 mg of tetrakis(triphenylphosphine)palladium, and 3 mL of chlorobenzene were subjected to three freeze-pump-thaw cycles to remove oxygen under argon. Under nitrogen protection, the reaction was stirred at 115 °C for 72 h and then cooled to room temperature. 200 mL of methanol was added, and the mixture was stirred at room temperature for 0.5 h. After filtration, the obtained polymer was loaded into a Soxhlet extractor for extraction. It was successively extracted with methanol, acetone, and petroleum ether until colorless to remove small molecules and catalysts, and then extracted with chloroform. The chloroform was evaporated to dryness to obtain a black solid with a metallic luster, namely PBPTVT2 (yield = 88%).

[0139] The molecular weight and its molecular weight distribution are as follows: The weight-average molecular weight M w is 23.9 kDa, and the number-average molecular weight M n is 13.1 kDa. The polymer molecular weight distribution index is 1.82.

[0140] Determination of the spectral properties and organic field-effect transistor device properties of the polymers PBPTVT1 and PBPTVT2 containing bipyridino[2,3-f:2′,3′-h]pyrazino[2,3-b:6,7-b′]diindole heterocyclic units prepared in the above Examples 1 and 2

[0141] (1) Absorption spectral properties of polymers PBPTVT1 and PBPTVT2 containing bipyridino[2,3-f:2′,3′-h]pyrazino[2,3-b:6,7-b′]diindole heterocyclic units

[0142] Figure 1 They are the ultraviolet-visible-near-infrared absorption spectra of the thin films of polymers PBPTVT1 and PBPTVT2 containing bipyridino[2,3-f:2′,3′-h]pyrazino[2,3-b:6,7-b′]diindole heterocyclic units on quartz wafers (the thin films were prepared by spin-coating a chloroform solution on quartz wafers). As Figure 1 can be seen, the thin films of polymers PBPTVT1 and PBPTVT2 containing bipyridino[2,3-f:2′,3′-h]pyrazino[2,3-b:6,7-b′]diindole heterocyclic units both exhibit a broad absorption range. The maximum absorption edge band values of their thin film absorptions are about 1194 nm and 1188 nm respectively, and the corresponding optical band gaps are 1.038 and 1.044 eV (the optical band gap is calculated according to the formula E g = 1240 / λ, where E g is the optical band gap and λ is the maximum absorption edge band value of the thin film absorption).

[0143] (2) Determination of the organic field-effect transistor performance of polymers PBPTVT1 and PBPTVT2

[0144] This invention uses a top-gate bottom-contact (TGBC) device structure to study the semiconductor characteristics of polymer thin films. The device structure is as shown in Figure 2 . The detailed device fabrication process is completed with reference to the literature (Adv. Mater., 2017, 29, 1602410). A highly doped silicon wafer is used as the substrate, and silicon dioxide is used as the insulating layer (300 nm); source / drain electrodes (gold / titanium, 30 nm / 5 nm) are prepared by photolithography. The channel width (W) of the FET device is 1400 μm, and the channel length (L) is 5 μm. The substrate is first treated with oxygen plasma for 5 minutes and then cleaned successively with acetone, deionized water, and ethanol. Then, under vacuum, the surface of the SiO 2 insulating layer is modified with octadecyltrichlorosilane (OTS), and then the OTS-modified substrate is placed in a vacuum oven at 60 °C for drying. In a nitrogen glove box, the semiconductor active layer is prepared by spin-coating a 8 - 15 mg / mL polymer dichlorobenzene solution, and the thin film sample is annealed at 180 °C for 10 min in the nitrogen glove box. The active layer is composed of the polymer PBPTVT1 obtained in Example 1 or the polymer PBPTVT2 obtained in Example 2. Subsequently, the thin film sample is annealed (180 °C) in a nitrogen atmosphere. Then, a poly(methyl methacrylate) (PMMA, about 1150 nm) dielectric layer is prepared by spin-coating an 80 mg / mL poly(methyl methacrylate) butyl acetate solution. The weight-average molecular weight of the used PMMA is 996 kDa, and the dielectric constant k is about 2.17. Then, the entire device is baked in a vacuum drying oven at 80 °C for 30 minutes to remove the butyl acetate solvent. Finally, an aluminum layer with a thickness of about 100 nm is evaporated on the PMMA dielectric layer as the gate electrode. In air, the semiconductor characteristics of the FETs are measured using a Keithley 4200SCS semiconductor tester, and the typical output and transfer curves are as shown in Figures 3 - 6 . Among them, the hole and electron mobilities in the saturation region can be calculated from the following equation: I DS =(W / 2L)C i μ(V G -V T ) 2 (saturation region, V DS =V G -V T ). Among them, I DS is the drain current, μ is the carrier mobility, V G is the gate voltage, V T is the threshold voltage, and C i is the insulator capacitance.

[0145] Figure 3The transfer characteristic curve of a field-effect transistor device with the polymer PBPTVT1 film containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit prepared in Example 1 as the organic active semiconductor layer at a source-drain voltage of 80 V. The device exhibits good device performance, with an electron mobility of 0.011 cm 2 / V s.

[0146] Figure 4 The output characteristic curve of a field-effect transistor device with the polymer PBPTVT1 film containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit prepared in Example 1 as the organic active semiconductor layer. The curve exhibits a good linear region and saturation region, indicating that the field-effect transistor device assembled with the polymer PBPTVT1 has good field-effect regulation performance.

[0147] Figure 5 The transfer characteristic curve of a field-effect transistor device with the polymer PBPTVT2 film containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit prepared in Example 2 as the organic active semiconductor layer at a source-drain voltage of 80 V. The device exhibits good device performance, with an electron mobility of 0.035 cm 2 / V s.

[0148] Figure 6 The output characteristic curve of a field-effect transistor device with the polymer PBPTVT2 film containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit prepared in Example 2 as the organic active semiconductor layer. The curve exhibits a good linear region and saturation region, indicating that the field-effect transistor device assembled with the polymer PBPTVT2 has good field-effect regulation performance.

[0149] In addition, the obtained research results confirm that: a class of polymers containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit provided by the present invention are a class of conjugated polymers with excellent comprehensive properties; this class of polymer semiconductor materials has a large coplanar backbone, strong heteroatom interactions, and good solution processability. The preparation method provided by the present invention has the advantages of simplicity, effectiveness, easy availability of raw materials, and strong popularization. By changing different solubilizing alkyl chains, heteroatom substitutions, and copolymerization units, a series of polymer materials containing a bipyridino[3,2-a]pyrazino[5,6-i]indacene heterocyclic unit with excellent comprehensive properties can be prepared, which is of great significance for studying the internal relationship between the structure and properties of polymer semiconductors and has guiding significance for the future development of n-type conjugated polymers with high mobility.

[0150] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A polymer containing a bipyridopyrazine indene heterocyclic unit, characterized in that: The chemical structural formula is shown in Formula I or Formula II: In Formula I and Formula II, R is a straight-chain alkyl group having a total number of carbon atoms of 6 to 16 or a branched-chain alkyl group having a total number of carbon atoms of 8 to 30; Ar is one of the structures shown below, but is not limited to the following structural formula, wherein the definition of R in Ar is the same as that of R in Formula I and Formula II; n is an integer from 10 to 300.

2. The polymer containing bipyridopyrazinoindene heterocyclic units according to claim 1, characterized in that: The straight-chain alkyl group having a total of 6 to 16 carbon atoms is one of n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl or n-hexadecyl.

3. The polymer containing bipyridopyrazinoindene heterocyclic units according to claim 1, characterized in that: The branched alkyl group having a total of 8 to 30 carbon atoms is one of 2-ethylhexyl, 2-butylhexyl, 2-hexyloctyl, 4-hexyldecyl, 3-hexylundecyl, 2-octyldecyl, 2-octyldodecyl, 3-octyltridecyl, 2-decyldodecyl, 2-decyltetradecyl, 3-decylpentadecyl, 2-dodecylhexadecyl, 4-octyltetradecyl, 4-decylhexadecyl, 4-octyldodecyl, 4-decyltetradecyl or 4-dodecylhexadecyl.

4. The polymer containing bipyridopyrazinoindene heterocyclic units according to claim 1, characterized in that: The chemical structure is shown in PBPTVT1: Wherein n is an integer from 10 to 300.

5. The polymer containing bipyridopyrazinoindene heterocyclic units according to claim 1, characterized in that: The chemical structure is shown in PBPTVT2: Wherein n is an integer from 10 to 300.

6. A method for preparing a polymer containing a bipyridopyrazinoindene heterocyclic unit according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, 2-tributyltin- 4-Alkylthiophene Mixed with 4,7-dibromo-[1,2,5]thiadiazo[3,4-c]pyridine and subjected to palladium-catalyzed Stille coupling reaction to obtain intermediate a; S2, selectively reducing the intermediate a with reducing zinc powder to obtain intermediate b; S3, subjecting the intermediate b to a condensation reaction with ninhydrin to obtain an intermediate c or an intermediate d, respectively; S4, mixing the intermediate c or intermediate d with hexa-n-butyl ditin respectively and performing a palladium-catalyzed Stille coupling reaction to obtain intermediate e and intermediate f respectively; S5, subjecting the intermediate e and intermediate f to nucleophilic substitution reaction under the action of malononitrile to obtain intermediate g and intermediate h, respectively; S6, subjecting the intermediate g or the intermediate h to electrophilic substitution reaction with N-bromosuccinimide to obtain compound M1 and compound M2, respectively; S7, subjecting the compound M1 or the compound M2 to a Stille coupling condensation reaction with a bis(trimethyltin)-substituted aromatic heterocyclic monomer g in the presence of a palladium catalyst to obtain polymers containing bipyridopyrazinoindene heterocyclic units having the structural formulas of Formula I and II, respectively; Wherein, the structural formula of the intermediate a is: The structural formula of the intermediate b is: The structural formula of the intermediate c is: The structural formula of the intermediate d is: The structural formula of the intermediate e is: The structural formula of the intermediate f is: The structural formula of the intermediate g is: The structural formula of the intermediate h is: The structural formula of the compound M1 is: The structural formula of the compound M2 is: The structural formula of the bis(trimethyltin)-substituted aromatic heterocyclic monomer i is: Wherein, R is a straight-chain alkyl group having a total number of carbon atoms of 6 to 16 or a branched-chain alkyl group having a total number of carbon atoms of 8 to 30; Ar is one of the structures shown below, wherein the definition of R in Ar is the same as that of R in Formula I and Formula II; The n is an integer of 10 to 300.

7. The method for preparing a polymer containing a bipyridopyrazinoindene heterocyclic unit according to claim 6, characterized in that: The specific steps include: S1. Under nitrogen protection, 2-tributyltin-4-alkylthiophene, 4,7-dibromo-[1,2,5]thiadiazo[3,4-c]pyridine, a palladium catalyst and a solvent are mixed, and refluxed with stirring for 3 to 10 hours to obtain an intermediate a; the molar ratio of the 4,7-dibromo-[1,2,5]thiadiazo[3,4-c]pyridine, 2-tributyltin-4-alkylthiophene and the palladium catalyst is 1.0:1.0-3.0:0.01-0.1; S2. Under nitrogen protection, the intermediate a, reduced zinc powder and solvent are mixed, and refluxed and stirred for 3 to 10 hours to obtain the intermediate b; the molar ratio of the intermediate a to the zinc powder is 1.0:3.0 to 10.0; S3, adding the intermediate b and ninhydrin hydrate into a solvent, mixing, reflux stirring for 1 to 3 hours, and obtaining intermediate c and intermediate d respectively; the molar ratio of the ninhydrin hydrate to the intermediate a in step S2 is 3.0 to 10.0:1.0; S4, under nitrogen protection, the intermediate c or intermediate d, hexa-n-butyl ditin, palladium catalyst and solvent are mixed, and refluxed and stirred for 3 to 10 hours to obtain intermediate e or intermediate f respectively; the molar ratio of the intermediate c or intermediate d, hexa-n-butyl ditin and palladium catalyst is 1.0:0.5-1:0.01-0.1; S5. Under nitrogen protection, add intermediate e or intermediate f, malononitrile, dichloromethane and pyridine to a three-necked flask in sequence, and finally slowly add titanium tetrachloride, and stir the reaction at 40°C for 10 to 20 hours to obtain intermediate g and intermediate h respectively; the usage ratio of intermediate e or intermediate f, pyridine and malononitrile is 1.0 mmol: 4.0 to 10.0 mmol: 1.0 to 2.0 mL; S6. Under nitrogen protection, the intermediate g or the intermediate h is mixed with a solvent; then N-bromosuccinimide is added to the mixture, and the mixture is stirred at room temperature for 5 to 10 hours to obtain compound M1 and compound M2, respectively; the molar ratio of the intermediate g or the intermediate h to N-bromosuccinimide is 1:2.0 to 3.0; S7. Mix the compound M1 or compound M2, a bis(trimethyltin)-substituted aromatic heterocyclic monomer i, a solvent and a palladium catalyst, and react with stirring at 80°C to 150°C for 24 to 72 hours under nitrogen protection to obtain a polymer containing a bispyridopyrazinebisindene heterocyclic unit; the molar ratio of the compound M1 or M2, the bis(trimethyltin)-substituted aromatic heterocyclic monomer i and the palladium catalyst is 1:1.0-1.5:0.01-0.

1.

8. The method for preparing a polymer containing a bipyridopyrazinoindene heterocyclic unit according to claim 7, characterized in that: The palladium catalyst is one or more of tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride and tris(dibenzylideneacetone)dipalladium.

9. The method for preparing a polymer containing a bipyridopyrazinoindene heterocyclic unit according to claim 7, characterized in that: The solvent is one or more of toluene, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, chlorobenzene, dichlorobenzene, trichlorobenzene and tetrahydrofuran.

10. Use of the polymer containing bipyridopyrazinoindene heterocyclic units according to any one of claims 1 to 5 in the preparation of organic field effect transistor devices.

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