Method for synthesizing n-type conductive conjugated polymer and screening catalyst

Abstract

The invention discloses a method for synthesizing an n-type conductive conjugated polymer and screening a catalyst, and belongs to the technical field of synthesis of conductive polymer materials. Redox potentials of various metal compounds are studied, the screening method of the catalyst in synthesis of the n-type conductive conjugated polymer is provided, and the n-type conductive conjugated polymer such as poly (benzodifuran diketone) (PBFDO) is efficiently synthesized by introducing a trace and cheap metal compound as the catalyst. The method has the advantages that the problem that a large amount of catalyst is left in a conventional synthesis method is solved, the operation is simple, the conductivity of the synthesized PBFDO exceeds # imgabs0 #, the problem that most n-type organic conductive polymers are low in conductivity is solved, high-performance conductivity matched with p-type organic conductive polymers can be realized, and the method can be widely applied to various organic functional materials and organic electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of the synthesis of conductive polymer materials, and in particular relates to an efficient synthesis method of n-type conductive polymers such as poly(benzodifurandione) (PBFDO), a screening method of the catalysts used, and applications in the fields of organic functional materials and organic electronics. Background Art

[0002] Metal compounds have been widely used as catalysts in organic chemical reactions, and the most representative one is the Suzuki coupling reaction commended by the Nobel Prize in Chemistry in 2010. In this reaction, zerovalent palladium catalyzes the cross-coupling of aryl or alkenyl boronic acid / boronate with chloro-, bromo-, iodo-aromatic hydrocarbons or alkenes under the action of ligands, thereby realizing the diversified construction of molecular skeletons and providing an important path for the development of organic synthesis methodology.

[0003] Recently, Huang et al. first synthesized an n-type conductive polymer, poly(benzodifurandione) (PBFDO), with a conductivity as high as . The synthesis of this polymer uses duroquinone as an oxidant to carry out oxidative polymerization with 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (HBFDO), and in-situ reduction doping is realized during the reaction process, significantly improving the doping efficiency. The obtained product has excellent stability and good solution processability (Nature 2022, 611, 271 - 277). As an n-type highly conductive polymer material without a solubilizing side chain, PBFDO not only has high conductivity but also good optical transparency, and its discovery is considered an important breakthrough in the field of organic semiconductors.

[0004] The fundamental reason for this breakthrough is that organic conductive polymers have become the core of the research on a new generation of organic functional materials and organic electronics due to their unique conjugated structure, good solution processability, and flexible characteristics. Conjugated polymers endow materials with unique optical, electrical, and magnetic properties through a delocalized π-electron system and are widely used in fields such as organic solar cells (OPV), organic light-emitting diodes (OLED), organic field-effect transistors (OFET), organic thermoelectric devices (OTE), and organic electrochemical transistors (OECT). However, the construction of high-performance devices relies on the collaborative work of p-type and n-type semiconductor materials. Compared with p-type materials (hole-transporting materials) that have been deeply studied, developed rapidly, and widely applied, n-type materials (electron-transporting materials) have lagged behind in long-term development, mainly limited by their low mobility, poor doping efficiency, insufficient stability, and lack of systematic research on the structure-property relationship, which has become one of the key factors restricting the further improvement of the performance of organic electronic devices.

[0005] With the advent of the high-conductivity n-type polymer PBFDO, research on its synthesis, structure regulation, and performance optimization has rapidly unfolded and become a research hotspot in this field. Compared with the traditional synthesis method of PBFDO that requires reactions in an inert atmosphere, Mei et al. developed a new method for synthesizing PBFDO in 2023 through a cascade reaction using soluble copper acetate as a catalyst in an air atmosphere (J. Am. Chem. Soc. 2023, 145, 3706 3715). Although this method reduces the requirements for the reaction atmosphere, similar to existing synthesis methods (such as CN 115490835 A and CN 119569998 A), it still requires the addition of a large amount of catalyst, resulting in an increase in reaction costs and introducing complex dialysis treatment steps, which are not only time-consuming and laborious but also consume a large amount of organic solvents, significantly increasing the process cost and technical barriers.

[0006] To further simplify the synthesis process, Yang et al. used α-tocopherolquinone (α-TQ) as a catalyst to synthesize PBFDO, effectively avoiding the dialysis step, providing the possibility for large-scale production, and the conductivity of the obtained polymer can reach (Adv. Mater. 2025, 2502426. https: / / doi.org / 10.1002 / adma.202502426). However, this method still has problems such as a large amount of catalyst addition, the need to operate in a nitrogen atmosphere, and high residual amounts of α-TQ and its reduction product (α-TOH), which limit its further application in high-purity electronic devices.

[0007] In addition, Mei et al. also reported a method using Method for preparing PBFDO by catalyzing Riley oxidation and aldol condensation reaction of HBFDO. By regulating parameters such as solvent system, temperature, time, and material ratio, a product with a conductivity as high as can be obtained (Angew. Chem. Int. Ed. 2025, 64, e202418668). Although this method does not require dialysis treatment, the reaction still needs to be carried out in an inert atmosphere, and a relatively large amount of catalyst needs to be introduced. The content of by-product elemental Se generated is relatively high in the reaction solution, resulting in the need to rely on filtration and repeated centrifugation operations during the post-treatment process, increasing the operation complexity and being unfavorable for large-scale continuous production.

[0008] Therefore, how to reasonably screen efficient catalysts and develop a synthesis process for n-type highly conductive conjugated polymers with low cost, low residue, simple post-treatment process, and excellent solution processability is a key technical problem that urgently needs to be solved for the large-scale application of organic electronic devices. Summary of the Invention

[0009] In order to overcome the above-mentioned disadvantages and deficiencies of the prior art, the purpose of the present invention is to provide a method for efficiently synthesizing n-type conductive conjugated polymers such as poly(benzodifurandione) (PBFDO). This method successfully synthesizes PBFDO with a conductivity exceeding by introducing a trace amount of inexpensive metal compound as a catalyst, making up for the problem of low conductivity of most n-type organic conductive polymers, and being able to achieve high-performance conductivity matching that of p-type, providing a new synthesis method and idea for the development of this material.

[0010] To achieve the above technical purpose, the present invention first studies the redox potentials of various metal compounds themselves and provides a screening method and criteria for catalysts in the synthesis steps of n-type conductive conjugated polymers.

[0011] The n-type conductive conjugated polymers such as poly(benzodifurandione) (PBFDO) prepared by the efficient synthesis method of the present invention have excellent electrical conductivity and can be widely used in organic functional materials and organic electronics fields such as carbon nanotube purification, wet spinning, wet film, conductive fiber, organic light-emitting diode, organic field-effect transistor, organic electrochemical transistor, organic thermoelectricity, organic solar cell, and electromagnetic shielding.

[0012] The n-type conductive conjugated polymers in the present invention are homopolymers or copolymers, including one or more polymerization units, and the polymerization units are derived from monomers with the structure shown in formula (I):

[0013]

[0014] Formula (I)

[0015] Among them, Ar 1 is a polycyclic aromatic structure, such as benzene, naphthalene, anthracene, thiophene, bithiophene, pyrrole, bipyrrole, furan, bifuran, selenophene, biselenophene, tellurophene, bitellurophene, benzodithiophene, benzofuran, benzopyrrole, benzoselenophene, terthiophene, etc. are common, and it also contains different ring-fused sites in the polycyclic aromatic structure; R1 represents one or more identical or different substituents on Ar 1 , and is selected from a hydrogen atom, a halogen (F, Cl, Br, I), a cyano group, a nitro group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group, or a silicon-protected ethynyl group, etc.; X and Y are the same or different, and each independently is O, S, Se, Te or N-R2, where R2 is selected from a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen-substituted alkyl group, and a halogen-substituted cycloalkyl group.

[0016] Furthermore, when R1 is an alkyl group, it is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, etc.; when R1 is a halogen-substituted alkyl group, it is preferably a halogen-substituted C1-C4 alkyl group, such as a trifluoromethyl group; when R1 is an alkenyl group, it is preferably an alkenyl group having 3 to 12 carbon atoms, more preferably an alkenyl group having 3 to 6 carbon atoms, such as an allyl group, etc.; when R1 is an alkynyl group, it is preferably an alkynyl group having 2 to 6 carbon atoms, such as an ethynyl group, a propynyl group, etc.; when R1 is a silicon-protected ethynyl group, it is preferably an alkyl-silicon-protected ethynyl group, such as a triisopropylsilylethynyl group, a triisobutylsilylethynyl group, etc.

[0017] Preferably, X and Y are O, S or N-R2.

[0018] Preferably, R2 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen-substituted alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a halogen-substituted cycloalkyl group having 5 to 7 carbon atoms.

[0019] Several specific examples of the compound of formula (I) are given below.

[0020] When X and Y are oxygen atoms and Ar 1 is a benzene ring and there is no substituent R1, the compound of formula (I) is 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (abbreviation: benzo-furan dione, HBFDO), and its specific structure is as follows:

[0021]

[0022] When X and Y are oxygen atoms and Ar 1 is a naphthalene ring and there is no substituent R1, the specific structure of the compound of formula (I) includes the following three (different ring-fused sites in the polycyclic aromatic structure):

[0023]

[0024] When X and Y are sulfur atoms, and Ar 1 is a benzene ring and there is no substituent R1, the specific structure of the compound of formula (I) is as follows:

[0025]

[0026] When X and Y are N-R2, and Ar 1 is a benzene ring, and there is no substituent R1 on Ar 1 the specific structure of the compound of formula (I) is as follows:

[0027]

[0028] The n-type conductive conjugated polymer of the present invention has a structure specifically composed of formula (I) and formula (I). In this composed structure, the structural units of formula (I) and formula (I) can be the same or different, and can contain one or more structural units in formula (I). The neutral state (such as BFDO) and doped state (such as PBFDO) of the n-type conductive conjugated polymer are the structures of formula (II) and formula (III) respectively:

[0029]

[0030] Formula (II) Formula (III)

[0031] In formula (II) and formula (III), n is a positive integer representing the degree of polymerization; m is a positive integer with a value lower than n, representing the degree of reduction doping; Ar 1 R1, X, and Y in each polymerization unit are the same or different.

[0032] The method for efficiently synthesizing the above-mentioned n-type conductive conjugated polymer provided by the present invention is to disperse one or more monomers represented by formula (I) and a metal compound in an organic solvent under an air atmosphere, and then heat and react to obtain the n-type conductive conjugated polymer. Among them, the metal compound is used as a catalyst, is insoluble in the organic solvent, and under the reaction conditions, the redox potential of the metal compound satisfies the following relationship: E(neutral state of n-type conductive conjugated polymer / polymerization monomer) < E(high-valent metal compound / low-valent metal compound) < E(O2 / H2O).

[0033] In the method for efficiently synthesizing the n-type conductive conjugated polymer provided by the present invention, the amount of the metal compound used is 1 ppm to 0.01 times the equivalent of the monomer.

[0034] The fact that the metal compound is hardly soluble in the organic solvent means that the metal compound, whether in the high-valence state or the low-valence state, is always insoluble or slightly soluble in the reaction system solvent.

[0035] Taking poly(benzodifurandione) (PBFDO) as an example, its synthesis method includes the following steps:

[0036] In an air atmosphere, benzodifurandione (HBFDO) and a metal compound are dispersed in an organic solvent, and then heated for reaction. After the reaction is completed, the n-type conductive conjugated polymer PBFDO can be obtained.

[0037] According to Figure 1 the polymerization reaction mechanism of the n-type conductive polymer PBFDO, the metal compound can be oxidized to the high-valence state by oxygen and can be reduced to the low-valence state by HBFDO. Therefore, the redox potential of the metal compound needs to satisfy the following relationship: E(BFDO / HBFDO) < E(high-valence metal compound / low-valence metal compound) < E(O2 / H2O). Then, under standard conditions, their potential relationship is as follows: -2.25 V < E°(high-valence metal compound / low-valence metal compound) < 1.23 V, where the standard redox potential E°(BFDO / HBFDO) ≈ -2.25 V and E°(O2 / H2O) = 1.23 V. Based on this relationship, we have screened out the following 4 types of available metal compounds:

[0038] (1) Alkaline earth metals Table 1

[0039]

[0040] (2) Transition metals Table 2

[0041]

[0042] (3) Rare earth metals Table 3

[0043]

[0044] (4) Main group metals Table 4

[0045]

[0046] Therefore, the metal compounds described in the present invention are compounds in various poorly soluble forms of the above four types of metal ions, such as oxides, halides (including fluorides, chlorides, bromides, iodides), sulfides, salts, bases, acid salts, and so on. Among them, the various poorly soluble forms of the compounds of the above four types of metal ions refer to that during the synthesis process of the n-type conductive conjugated polymer, whether in the high-valent state or the low-valent state, the metal compound is always insoluble or slightly soluble in the reaction system solvent. For example, during the process of catalyzing the oxidation polymerization of HBFDO to BFDO and in-situ reduction to PBFDO by CuI, the metal element copper always exists in the form of fine particles in the reaction system. It not only provides adsorption sites for chemical substrates but also reduces the reaction barrier, activates the reaction process, promotes the atom or electron transfer of chemical substrates on the surface of metal particles, and greatly improves the reaction process. Therefore, only a trace amount of the metal compound in the poorly soluble form needs to be added to the reaction system to achieve an ideal catalytic effect. This point is particularly important and is the reason different from the previous report by Mei et al. that an ultra-high 1:1 equivalent of soluble copper acetate needs to be added to achieve an ideal catalytic effect (J. Am. Chem. Soc. 2023, 145, 3706 - 3715).

[0047] For the efficient synthesis reaction of PBFDO, preferably, the standard redox potential range of the metal ions is between -0.8 V and 0.8 V. For example, the standard redox potentials of cuprous particles and silver ions are E°(Cu + / Cu) = 0.5200 V and E°(Ag + / Ag) = 0.7996 V, respectively, both within the above range. Therefore, the use of compounds in the poorly soluble form containing these two metal ions can achieve the effect of good catalysis with a trace amount of addition. Specific data can be seen in Example 5 and Example 6.

[0048] The organic solvents are one or more mixtures of halogenated hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, sulfone solvents, ketone solvents, amide solvents, such as tetrahydrofuran, chloroform, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, trichlorobenzene, methanol, ethanol, propanol, ethylene glycol, isodimethylformamide, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, acetone, butanone, cyclohexanone, methyl butanone, methyl ether, ethyl ether, propyl ether, pyridine, phenol, N-methylpyrrolidone, etc. Preferably, polar aprotic solvents are selected, such as dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0049] In the above method for efficiently synthesizing n-type conductive conjugated polymers, the temperature of the heating reaction is set between 60 and 150 °C, and preferably, it is set to 80 °C.

[0050] The n-type conductive conjugated polymer solution prepared by the above reaction can be directly used for subsequent processing without additional post-treatment. Compared with the cumbersome post-treatment steps such as dialysis, centrifugation, and filtration usually required in the prior art, the present invention has significantly simplified the process flow by screening out efficient catalysts, and finally developed an n-type highly conductive conjugated polymer synthesis system with both low cost and excellent solution processability.

[0051] The n-type conjugated polymers synthesized according to the method of the present invention have a wide range of uses in the fields of organic functional materials and organic electronics, including but not limited to: the application of the n-type conjugated polymer in the electron transport layer, the application of the n-type conjugated polymer in thermoelectric materials, the application of the n-type conjugated polymer in electromagnetic shielding materials, the application of the n-type conjugated polymer in the purification of carbon nanotubes, the application of the n-type conjugated polymer in wet spinning, the application of the n-type conjugated polymer in wet films, the application of the n-type conjugated polymer in conductive fibers, the application of the n-type conjugated polymer in organic field effect transistors, the application of the n-type conjugated polymer in organic electrochemical transistors, and the application of the n-type conjugated polymer in organic electrochromism, etc.

[0052] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0053] (1) The present invention provides a novel method for synthesizing PBFDO and other n-type conjugated polymers, that is, polymers with excellent conductivity performance can be synthesized by using only a trace amount of catalyst, and this scheme solves the problem of a large amount of residual catalyst in conventional methods.

[0054] (2) The present invention provides a screening criterion for catalysts in the synthesis steps of n-type conductive conjugated polymers, which is convenient for finding catalysts with low toxicity, low cost, wide sources, and strong universality. The catalysts selected in the examples can catalyze the oxidative polymerization and reduction doping reactions of a variety of different system substrates.

[0055] (3) The synthesis steps of the present invention are simple to operate, and the post-treatment is simple and efficient, which is suitable for large-scale production and preparation.

[0056] (4) The polymers synthesized by the present invention have a wide range of applications and have great development potential in the fields of electromagnetic shielding, purification of carbon nanotubes, wet spinning, wet film formation, conductive fibers, solid-state batteries, electrochemical transistors, electrochromism, etc.

[0057] Table 5. Comparison of various parameters for synthesizing the n-type highly conductive polymer PBFDO in the present invention and the reported technologies

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 The figure shows the schematic diagram for the efficient synthesis of the n-type conductive conjugated polymer PBFDO according to the present invention, where: (a) shows the reaction mechanism of the polymerization of HBFDO catalyzed by a metal compound to generate PBFDO; (b) shows the screening range of the redox potential of the metal compound.

[0060] Figure 2 The figure shows the photos of the reaction solutions obtained in Examples 1 to 7 (from left to right) of the present invention.

[0061] Figure 3 The figure shows the ultraviolet-visible-near infrared absorption spectra of the n-type conjugated polymers in Examples 1, 3, and 6 of the present invention in the solution state.

[0062] Figure 4 The figure shows the dynamic light scattering diagrams of the three n-type conjugated polymers in Examples 1, 3, and 6.

[0063] Figure 5 The figure shows the ultraviolet-visible-near infrared absorption spectrum of the carbon nanotube solution purified from the n-type conjugated polymer PBFDO-2 in Example 2.

[0064] Figure 6 The figure shows the structure diagram (a) and transfer curve (b) of the fiber OECT prepared by wet spinning of the n-type conjugated polymer PBFDO-2 in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0065] The present invention will be further described in detail below in conjunction with the examples and the drawings, but the implementation manners of the present invention are not limited thereto. For those conditions not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained by purchasing in the market.

[0066] One of the raw materials in the embodiments of the present invention, 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione, with a CAS number of 30272-74-3, was prepared according to the literature (A BDOPV-Based Donor–Acceptor Polymer for High-Performance n-Type and Oxygen-Doped Ambipolar Field-Effect Transistors. Adv.Mater. 2013, 25(45), 6589); other oxidizing metal compounds used in the embodiments are all common commercially available chemical raw materials.

[0067] The ratio of the raw materials and the catalytic metal compound used in the present invention is less than or equal to a molar ratio of 1:0.01, such as 1:0.01, 1:0.001, 1:0.0005, etc. Although the catalytic effect of the metal compound is very efficient, its usage amount is not zero.

[0068] When the raw materials and the catalytic metal compound react, there are no special requirements for the reaction temperature, as long as the reaction can proceed, for example: the reaction temperature is 60~150°C.

[0069] After the reaction is completed, no further treatment is required. After the stock solution returns to room temperature, it can be used after homogenization.

[0070] Example 1

[0071]

[0072] Under an air atmosphere, cobalt oxide (0.59 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol), and the mixture was heated to 80°C and reacted for 7 h. Subsequently, the solution was returned to room temperature and homogenized at room temperature at 6000 rpm for 30 min to obtain the n-type conjugated polymer PBFDO-1, with Mn = 73 kDa and PDI = 2.03.

[0073] Example 2

[0074]

[0075] Under an air atmosphere, molybdenum trioxide (1.14 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 7 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-2, with Mn = 47 kDa and PDI = 3.56.

[0076] Example 3

[0077]

[0078] Under an air atmosphere, vanadium dioxide (0.65 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 12 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-3, with Mn = 42 kDa and PDI = 5.43.

[0079] Example 4

[0080]

[0081] Under an air atmosphere, iron oxide (1.26 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 7 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-4, with Mn = 64 kDa and PDI = 2.76.

[0082] Example 5

[0083]

[0084] Under an air atmosphere, cuprous oxide (0.11 mg, 0.00079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 4 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-5, with Mn = 84 kDa and PDI = 3.47.

[0085] Example 6

[0086]

[0087] Under an air atmosphere, silver oxide (1.83 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 4 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-6, with Mn = 43 kDa and PDI = 2.75.

[0088] Example 7

[0089]

[0090] Under an air atmosphere, zinc oxide (0.64 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 80 °C and reacted for 7 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-7, with Mn = 54 kDa and PDI = 3.83.

[0091] Comparative Example 8

[0092]

[0093] Under an air atmosphere, ferric chloride (1.28 mg, 0.0079 mmol) and 10 mL of dimethyl sulfoxide (DMSO) were added to a round-bottom flask containing benzodifurandione (150 mg, 0.79 mmol). The mixture was heated to 100 °C and reacted for 7 h. Subsequently, the solution was returned to room temperature and homogenized at 6000 rpm for 30 min at room temperature to obtain the n-type conjugated polymer PBFDO-8, with Mn = 17 kDa and PDI = 4.35. In Comparative Example 8, although the redox potential of ferric ions (-0.037 V) is within the preferred potential of the catalyst (-0.8 V to 0.8 V), the selected metal compound ferric chloride is soluble in the DMSO solvent, making it unable to provide enough reaction sites. Therefore, the catalyst activity is greatly reduced, and it cannot achieve the expected catalytic effect.

[0094] Figure 2 For the reaction solutions of Examples 1 to 7, the ultraviolet-visible-near-infrared absorption spectra of the three n-type conjugated polymers in Examples 1, 3, and 6 are shown in Figure 3It can be seen that the three n-type conjugated polymers exhibit similar absorption peaks and all show strong absorption peaks in the near-infrared region, suggesting that their conjugated backbones contain polaron or bipolaron characteristics. In Figure 4 In this study, we used dynamic light scattering (DLS) measurement to compare the particle sizes of n-type conjugated polymers synthesized by three different metal compounds. In Examples 1, 3, and 6, the average particle size of the three samples was 71.32 nm, 53.21 nm, and 93.29 nm, respectively. The larger particle size distribution means that the polymerization degree in Example 6 is higher, so larger nanoparticle sizes are obtained.

[0095] Test Example 1 Solution Conductivity Test

[0096] For the seven batches of n-type conjugated polymers PBFDO-1 to 7 obtained in Examples 1 to 7, 40 μL of the solution was respectively dropped on a pre-treated substrate, annealed at 80 °C for 60 min, and then the conductivity data was collected by four-probe measurement using a Keithley 4200 SCS parameter analyzer. The results are shown in Table 6 below.

[0097] The seven n-type conjugated polymers PBFDO-1 to 7 all showed a conductivity higher than 2000 S / cm at a thickness below 100 nm, indicating that the metal compounds screened by this method have good catalytic efficacy for such polymerization reactions.

[0098] Table 6. Conductivity Test of Seven n-Type Conjugated Polymers in Examples 1 to 7

[0099]

[0100] Test Example 2 Carbon Nanotube Purification

[0101] Dissolve 0.3 mL of the n-type conjugated polymer PBFDO-2 in Example 2 and 15 mg of Arc carbon nanotubes in 25 mL of o-xylene, and perform ultrasonic dispersion with a cell crusher. The ultrasonic power is set to 300 W and the time is 30 min. During the ultrasonic dispersion process, use a circulating cooling device to cool the ultrasonic solution, and strictly control the system temperature to maintain at 0 °C. The circulating cooling device includes a circulating cooling instrument and a double-walled container. The ultrasonic solution is placed in the double-walled container, and the circulating coolant is passed between the inner and outer layers of the double-walled container to cool the ultrasonic solution, so that the system temperature is maintained at a fixed temperature.

[0102] Immediately after ultrasonic dispersion, perform ultracentrifugation at a centrifugal speed of 30000 rpm for 30 min, and the temperature is set to 16 °C. Extract the supernatant for ultraviolet-visible-near-infrared absorption spectroscopy test.

[0103] The absorption in the M11 region of metallic carbon nanotubes is at 600 - 800 nm, and the S22 absorption of semiconducting single-walled carbon nanotubes is at 800 - 1200 nm. As can be seen from Figure 5 it, after purification with PBFDO-2, the absorption of the carbon nanotube solution at 600 - 800 nm is greatly reduced, demonstrating that the metallic carbon nanotubes have been removed and the semiconducting carbon nanotubes have been effectively purified.

[0104] Test Example 3 Preparation of Conductive Fibers by Wet Spinning and Performance Characterization of OECT

[0105] Take 20 mL of PBFDO-2 solution (with DMSO as the solvent), stir it thoroughly for 30 min, and then perform ultrasonic treatment for 30 min to remove the air bubbles in the solution, obtaining a spinning solution. Draw 10 mL of the spinning stock solution with a syringe, fix the syringe on an injection pump, and inject the spinning stock solution into a coagulation bath containing isopropyl alcohol or tetrahydrofuran or ethyl acetate, etc. at different injection speeds (0.02 mL / min to 0.2 mL / min). The solution undergoes phase transition and solidifies into as-spun fibers in the coagulation bath, and the as-spun fibers are collected on a collecting roller. After the as-spun fibers are soaked in a secondary coagulation bath and stretched, DMSO is completely removed, obtaining well-shaped PBFDO-2 fibers. These PBFDO-2 fibers can be further stretched and annealed on a heating roller to further improve the fiber orientation and mechanical strength, and finally the obtained PBFDO-2 fibers are collected on a fiber collecting roller.

[0106] Use the above-prepared PBFDO-2 fibers to fabricate an organic electrochemical transistor (OECT) device, and the steps are as follows: First, place the PBFDO-2 fibers on the surface of a SiO2 silicon wafer through van der Waals interactions, then fix a metal mask plate above the fibers, and construct gold electrodes by thermal evaporation to construct a fiber OECT device as Figure 6 shown. The channel length of the fiber OECT device fabricated by this method is determined by the mask plate size (40 μm - 200 μm), and the channel width is the fiber diameter (which can be regulated by the nozzle diameter). The output curve and transfer curve of the PBFDO-2 fibers are obtained through a probe station and a source meter, and the figure of merit of the fiber OECT device is calculated according to the following formula .

[0107]

[0108] where g m is the transconductance, W is the channel width, L is the channel length, d is the fiber diameter, V Th is the threshold voltage, and V GS is the gate drive voltage.

[0109] An example of the output curve of the OECT device based on PBFDO-2 fiber is as Figure 6 shown. The PBFDO-2 fiber exhibits obvious n-type electron transport performance. The threshold voltage corresponding to this schematic diagram is for , and the maximum transconductance g m is 0.004 S.

[0110] The above test examples illustrate that the n-type conjugated polymer synthesized by the present invention can be widely applied in various organic optoelectronic devices.

Claims

1. A method for synthesizing an n-type conductive conjugated polymer, wherein the n-type conductive conjugated polymer is a homopolymer or copolymer obtained by polymerizing one or more monomers represented by formula (I); Formula (I) In formula (I), Ar 1 is a polycyclic aromatic structure; R1 represents one or more identical or different substituents on Ar 1 , selected from a hydrogen atom, a halogen, a cyano group, a nitro group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group or a silicon-protected ethynyl group; X and Y are the same or different and are each independently O, S, Se, Te or N-R2, where R2 is selected from a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen-substituted alkyl group and a halogen-substituted cycloalkyl group; It is characterized in that In an air atmosphere, one or more monomers represented by formula (I) and a metal compound are dispersed in an organic solvent, and then heated to react to obtain an n-type conductive conjugated polymer. Among them, the metal compound serves as a catalyst and is insoluble in the organic solvent. And under the reaction conditions, the redox potential of the metal compound satisfies the following relationship: E(neutral state of n-type conductive conjugated polymer / polymerization monomer) < E(high-valent metal compound / low-valent metal compound) < E(O2 / H2O); wherein, the neutral state of the n-type conductive conjugated polymer has the structure shown in formula (II): Formula (II) Among them, n is a positive integer representing the degree of polymerization; Ar in each polymerization unit constituting the polymer of the formula (II) 1 , R1, X, and Y are the same or different.

2. The synthesis method of the n-type conductive conjugated polymer according to claim 1, characterized in that The dosage of the metal compound is 1 ppm to 0.01 times the monomer equivalent.

3. The synthesis method of the n-type conductive conjugated polymer according to claim 1, characterized in that, The n-type conductive conjugated polymer is poly(benzodifurandione) PBFDO. In an air atmosphere, benzodifurandione HBFDO and a metal compound are dispersed in an organic solvent, and then heated to react. After the reaction, an n-type conductive conjugated polymer PBFDO is obtained; wherein: n is a positive integer representing the degree of polymerization; m is a positive integer with a value lower than n, representing the degree of reduction doping; The redox potential of the metal compound satisfies the following relationship: E(BFDO / HBFDO) < E(high-valent metal compound / low-valent metal compound) < E(O2 / H2O).

4. The synthesis method of the n-type conductive conjugated polymer according to claim 3, characterized in that, Under standard conditions, the redox potential of the metal compound satisfies the following conditions: -2.25 V < E°(high-valent metal compound / low-valent metal compound) < 1.23 V.

5. The synthesis method of the n-type conductive conjugated polymer according to claim 4, characterized in that, The metal compound is selected from oxides, halides, sulfides, salts, bases or acid salts of the following metal ions: ； The organic solvent is a polar aprotic solvent, and the metal compound is insoluble in the organic solvent.

6. A method for screening a catalyst, which is used to catalyze the polymerization of one or more monomers represented by formula (I) in an organic solvent under an air atmosphere to obtain an n-type conductive conjugated polymer: Formula (I) In formula (I), Ar 1 is a fused-ring aromatic structure; R1 represents one or more identical or different substituents on Ar 1 , selected from a hydrogen atom, a halogen, a cyano group, a nitro group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group or a silicon-protected ethynyl group; X and Y are the same or different and are each independently O, S, Se, Te or N-R2, where R2 is selected from a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen-substituted alkyl group and a halogen-substituted cycloalkyl group; It is characterized in that, Screen a metal compound that is insoluble in the organic solvent as a catalyst from metal compounds whose redox potential satisfies the following relationship: E(neutral state of n-type conductive conjugated polymer / polymerization monomer) < E(high-valent metal compound / low-valent metal compound) < E(O2 / H2O).

7. The screening method of the catalyst according to claim 6, characterized in that The metal compound is selected from oxides, halides, sulfides, salts, bases or acid salts of alkaline earth metals, transition metals, rare earth metals, and main group metals.

8. The screening method of the catalyst according to claim 6, wherein The n-type conductive conjugated polymer is poly(benzodifurandione) PBFDO, which is obtained by polymerizing benzodifurandione HBFDO. The catalyst used in the polymerization reaction is screened from metal compounds according to the following conditions: 1) Under standard conditions, the redox potential of the metal compound satisfies the following conditions: -2.25 V < E°(high-valent metal compound / low-valent metal compound) < 1.23 V; 2) The metal compound is insoluble in the organic solvent used in the polymerization reaction.

9. The method for screening a catalyst according to claim 8, wherein, Screen the catalyst from compounds containing the following metal ions: 。 10. An n-type conductive conjugated polymer solution obtained by the synthesis method according to any one of claims 1 to 5.

11. Use of the n-type conductive conjugated polymer solution according to claim 10 in the preparation of organic functional materials and organic electronics devices.

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