Ternary random conjugated polymer based on pyrazine-2-carboxylate unit as well as preparation method and application of ternary random conjugated polymer

Abstract

The invention provides a ternary random conjugated polymer based on a pyrazine-2-carboxylic ester unit as well as a preparation method and application of the ternary random conjugated polymer. The ternary random conjugated polymer based on the pyrazine-2-carboxylic ester unit has a structure as shown in a general formula I, the ternary random conjugated polymer disclosed by the invention has the advantages of good light absorption property, proper electronic energy level and the like, and can effectively reduce the energy level of the polymer under the condition that the optical band gap of the polymer is basically not influenced, so that the open-circuit voltage and the photoelectric conversion efficiency of a device are improved. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the field of molecular technology, and specifically relates to a ternary random conjugated polymer based on pyrazine-2-carboxylate units, and a preparation method and application thereof. Background Art

[0002] Organic solar cells (OSCs) are excellent candidates for energy harvesting applications in many self-powered devices due to their light weight, mechanical flexibility and low toxicity (G. Zhang, F. R. Lin, F. Qi, T. Heumüller, A. Distler, H.-J. Egelhaaf, N. Li, P. C. Y. Chow, C. J. Brabec, A. K. Y. Jen, H.-L. Yip, Chem. Rev. 2022, 122, 14180; J. Yi, G. Zhang, H. Yu, H. Yan, Nat. Rev. Mater. 2023, 9, 46.). So far, OSCs have achieved a power conversion efficiency (PCE) of 20%, and the best performing devices often use Y-series non-fullerene small molecule acceptors and pair them with donor polymers such as PM6 or D18 (Z. Chen, J. Ge, W. Song, X. Tong, H. Liu, X. Yu, J. Li, J. Shi, L. Xie and C. Han, Adv. Mater., 2024, 36, 2406690; Y. Sun, L. Wang, C. Guo, J. Xiao, C. Liu, C. Chen, W. Xia, Z. Gan, J. Cheng and J. Zhou, J. Am. Chem. Soc., 2024, 146, 12011-12019.). In order to promote the further development of OSCs, it is of great significance to design more efficient wide bandgap polymer donors and expand the high-performance donor family.

[0003] The terpolymer strategy introduces a third component into a high-performance donor polymer. By controlling the proportion of the third component, the basic properties of the material, such as energy levels, absorption spectra, aggregation, and crystallinity, can be effectively adjusted. This inevitably leads to molecular disorder, increases the main chain entropy, and reduces the crystallization tendency of the terpolymer. However, the intermolecular binding force imparted by secondary bonding using ester, cyano, chlorinated, and fluorinated third components can successfully offset the main chain disorder during crystallization (Z. Liao, K. Yang, L. Hou, J. Li, J. Lv, R. Singh, M. Kumar, Q. Chen, X. Dong, T. Xu, C. Hu, T. Duan, Z. Kan, S. Lu, Z. Xiao, Macromolecules 2020, 53, 9034; J. Wu, X. Guo, M. Xiong, X. Xia, Q. Li, J. Fang, X. Yan, Q. Liu, X. Lu, E. Wang, D. Yu, M. Zhang, Chem. Eng. J. 2022, 446, 137424; H. Sun, T. Liu, J. Yu, TK Lau, G. Zhang, Y. Zhang, M. Su, Y. Tang, R. Ma, B. Liu, J. Liang, K. Feng, X. Lu, X. Guo, F. Gao, H. Yan, Energy Environ. Sci. 2019, 12, 3328.).

[0004] Therefore, it is of great significance to improve the performance of solar cells by selecting appropriate donor and acceptor unit types and developing new donor materials to significantly improve their energy conversion efficiency. To this end, the present invention is proposed. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a ternary random conjugated polymer based on pyrazine-2-carboxylate units and a preparation method and application thereof. The ternary random conjugated polymer of the present invention has the advantages of good light absorption, suitable electronic energy level, etc., and can effectively reduce the energy level of the polymer without substantially affecting the optical band gap of the polymer, thereby improving the open circuit voltage and photoelectric conversion efficiency of the device.

[0006] The technical solution of the present invention is as follows:

[0007] A ternary random conjugated polymer based on pyrazine-2-carboxylate units has a structure shown in the following general formula I:

[0008]

[0009] Among them, in the general formula Ⅰ,

[0010] R1, R2, R3, R4 and R5 are each independently selected from hydrogen, an alkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a siloxane group, an ester group, an aryl group, an aralkyl group, a haloalkyl group, a heteroalkyl group or an alkenyl group;

[0011] X is independently selected from one of hydrogen and halogen atoms;

[0012] n represents the number of repeating units of the polymer, which is selected from a natural number between 1 and 5000;

[0013] y is 0.01 to 0.99, and x+y=1.

[0014] Preferably according to the present invention, in the general formula I, R1, R2, R3, R4 and R5 are independently selected from an alkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a siloxane group, an ester group; and X is selected from F or Cl.

[0015] Preferably according to the present invention, in the general formula I, y is 0.05-0.5.

[0016] Preferably according to the present invention, the number average molecular weight of the ternary random conjugated polymer based on pyrazine-2-carboxylate units is 1,000 to 1,000,000, preferably 20,000 to 500,000.

[0017] According to the present invention, the preparation method of the above-mentioned ternary random conjugated polymer based on pyrazine-2-carboxylate units comprises the following steps:

[0018] The compound represented by formula II, the compound represented by formula III and the compound represented by formula IV are subjected to a ternary random copolymerization reaction under the action of a catalyst to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylate units;

[0019]

[0020] in,

[0021] In the compound represented by Formula II, the substituents R1 and X are the same as the substituents R1 and X in Formula I; Y1 is selected from any one of a boric acid group, a zinc halide group or a trialkyltin group;

[0022] In the compound represented by formula III, the substituent R2 is the same as the substituent R2 in the general formula I; Y2 is selected from one of I, Br or Cl;

[0023] In the compound represented by formula IV, the substituents R3, R4 and R5 are the same as the substituents R3, R4 and R5 in the general formula I; and Y3 is selected from one of I, Br or Cl.

[0024] Preferably according to the present invention, the boronic acid group is selected from one of 1,3,2-dioxaborolane-2-yl, 4,4,5,5-tetramethyl-1,2,3-dioxaborolane-2-yl or 5,5-dimethyl-1,3,2-dioxaborolane-2-yl; the zinc halide group is selected from zinc chloride or zinc bromide; the trialkyltin group is selected from one of trimethyltin, triethyltin or tributyltin.

[0025] Preferably according to the present invention, the catalyst is any one of [1,3-bis(diphenylphosphino)propane]dichloronickel, tetrakis(triphenylphosphine)palladium, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate; the molar ratio of the catalyst to the compound represented by formula II is 0.001-0.5:1, and more preferably 0.01-0.1:1.

[0026] Preferably according to the present invention, a catalyst ligand is also added to the reaction system, and the catalyst ligand is any one of tri(o-methylphenyl)phosphine, tributylphosphine or tricyclohexylphosphine, and the molar ratio of the catalyst to the catalyst ligand is 1:1-20, and more preferably 1:2-10.

[0027] Preferably according to the present invention, the molar ratio of the compound represented by formula III to the compound represented by formula IV is 99:1 to 1:99, and more preferably 95:5 to 50:50; the ratio of the total molar number of the compound represented by formula III and the compound represented by formula IV to the molar number of the compound represented by formula II is 1:1.

[0028] Preferably according to the present invention, the copolymerization reaction is carried out in a solvent, and the solvent is any one of anhydrous toluene, anhydrous chlorobenzene, and anhydrous o-xylene; the ratio of the volume of the solvent to the molar number of the compound represented by formula II is 10-100 mL:1 mmol.

[0029] Preferably according to the present invention, the copolymerization reaction temperature is 80-200° C., more preferably 100-150° C., the heating method is oil bath heating or microwave heating; the reaction time is 0.5-48 hours; the copolymerization reaction is carried out under argon protection.

[0030] Preferably, according to the present invention, the post-treatment steps of the reaction liquid obtained by the copolymerization reaction are as follows: the reaction mixture is precipitated in methanol, the solid is collected by filtration, and Soxhlet extraction is performed with acetone, n-hexane, dichloromethane, chloroform, and chlorobenzene, respectively, the chlorobenzene extract is concentrated and then precipitated in methanol to obtain a solid polymer, which is filtered and the obtained solid is vacuum dried at 50-60°C for 3-24 hours.

[0031] According to the present invention, the above-mentioned ternary random conjugated polymer based on pyrazine-2-carboxylate units is used in thin-film semiconductor devices, electrochemical devices, photovoltaic devices and photoelectric devices; preferably, the device is specifically a polymer solar cell device or a photodetector device, and the polymer solar cell device is further a polymer solar cell device comprising a bulk heterojunction structure.

[0032] The ternary random conjugated polymer based on pyrazine-2-carboxylate unit base of the present invention is composed of a semiconductor composition and an additive; the additive is selected from fullerene derivatives or non-fullerene N-type organic semiconductors.

[0033] When a ternary conjugated polymer based on pyrazine-2-carboxylate units is used in a photovoltaic device, the photovoltaic device includes a hole collection layer, an electron collection layer, and a photovoltaic material layer between the hole collection layer and the electron collection layer, and the photovoltaic material layer contains the conjugated polymer; when a conjugated polymer based on pyrazine-2-carboxylate units is used in a photoelectric device, the photoelectric device includes a first electrode, a second electrode separated from the first electrode, and at least one active material layer arranged between the first electrode and the second electrode; the active material layer contains the conjugated polymer.

[0034] The technical features and beneficial effects of the present invention are as follows:

[0035] The invention provides a ternary conjugated polymer based on pyrazine-2-carboxylate units. A ternary random conjugated polymer is obtained by introducing a pyrazine-2-carboxylate unit with a specific structure as a third component into a main chain of a DA conjugated polymer (for example, D18), and the performance of the polymer material is regulated by adjusting the functional group modification or the alkyl chain length on the donor and acceptor units, so that the obtained polymer has a lower electronic energy level, better molecular arrangement, higher hole mobility and better device photovoltaic performance without substantially affecting the optical band gap of the polymer. The polymer of the invention has the advantages of good light absorption, suitable electronic energy level and the like, and can effectively reduce the energy level of the polymer without substantially affecting the optical band gap of the polymer, thereby improving the open circuit voltage and photoelectric conversion efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a gel permeation chromatogram of a ternary random conjugated polymer based on pyrazine-2-carboxylate units prepared in Example 1;

[0037] Figure 2 is a UV-visible absorption spectrum of the ternary random conjugated polymer based on pyrazine-2-carboxylate units prepared in Example 1;

[0038] Figure 3This is a JV curve diagram of the ternary random conjugated polymer based on pyrazine-2-carboxylate units prepared in Example 1 applied to organic solar cells;

[0039] Figure 4 is a gel permeation chromatogram of a ternary random conjugated polymer based on pyrazine-2-carboxylate units prepared in Example 2;

[0040] Figure 5 This is a JV curve diagram of the ternary random conjugated polymer based on pyrazine-2-carboxylate units prepared in Example 2 applied to organic solar cells. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and embodiments. However, the present invention is not limited to the embodiments listed, and should also include any other known changes within the scope of the rights claimed by the present invention.

[0042] First, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0043] Secondly, the present invention is described in detail using structural schematic diagrams, etc. When describing the embodiments of the present invention in detail, for the sake of convenience, the schematic diagrams will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space of length, width and depth should be included.

[0044] Example 1

[0045] The preparation method of the ternary random conjugated polymer based on pyrazine-2-carboxylate unit, the specific reaction route is as follows:

[0046]

[0047] The specific operations are as follows:

[0048] In a 25mL two-necked round-bottom flask, 0.1mmol of ditin monomer M1, 0.08mmol of dibrominated monomer M2, 0.02mmol of dibrominated monomer M3, 0.002mmol Pd2(dba)3, 0.008mmol P(o-tol)3 and 5mL of anhydrous toluene were added respectively, and the reaction mixture was passed through argon for 10 minutes; the reaction mixture was stirred and heated in an oil bath at 110°C for 5 hours under argon protection; after the polymerization, the reaction mixture was precipitated in 100mL of methanol, and the solid was collected by filtration, and Soxhlet extraction was performed with acetone, n-hexane, dichloromethane, chloroform and chlorobenzene respectively, the chlorobenzene extract was concentrated and precipitated in 100mL of methanol to obtain a solid polymer, and finally the solid was vacuum dried at 55°C for 10h to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylate units.

[0049] like Figure 1 The obtained polymer was treated with trichlorobenzene as solvent and its number average molecular weight (M n ) is 47.3 kDa and the dispersion index (PDI) is 2.13.

[0050] UV-Vis absorption spectrum test: The absorption spectrum of the solution uses chloroform as the solvent, and the polymer is prepared into a 2 mg / mL solution. The absorption sample of the film is a 10 mg / mL polymer chloroform solution spin-coated on a quartz plate at 3000 rpm for 30 seconds. The absorption spectra of the polymer in the chloroform solution and film state are as follows: Figure 2 As shown, the absorption spectra of the polymer in chloroform solution and film state are measured. The maximum absorption positions of the polymer in solution and film are 579nm and 578nm respectively.

[0051] Preparation and performance testing of organic solar cell devices: Commercially purchased indium tin oxide (ITO) glass was ultrasonically cleaned with detergent, water, deionized water, acetone, and isopropanol in turn, and then dried and spin-coated with a 30 nm thick PEDOT:PSS as an anode modification layer for standby use. A chloroform mixed solution of the ternary conjugated polymer based on pyrazine-2-carboxylate unit and the small molecule electron acceptor material L8-BO (weight ratio of 1:1.2) in Example 1 (the concentration of the ternary conjugated polymer based on pyrazine-2-carboxylate unit prepared in Example 1 in the mixed solution is 7 mg / mL) was spin-coated on the PEDOT:PSS anode modification layer to form the active layer of the device (thickness of 100 nm). Finally, a layer of PNDIT-F3N with a thickness of 10 nm was spin-coated as a cathode modification layer and Ag (100 nm) as the device cathode to obtain a polymer solar cell device. The effective area of ​​the photovoltaic device is 0.049 cm 2 , at 100mW / cm 2The photovoltaic performance of the device was tested under light intensity, and the three parameters of the polymer solar cell device, open circuit voltage, short circuit current and fill factor, were obtained. Its JV curve is shown in Figure 3 , where the open circuit voltage of the polymer solar cell device is V oc =0.94V, short circuit current J sc =26.1mA / cm 2 , filling factor FF = 69.4%, conversion efficiency PCE = 17.0%.

[0052] The structure of the small molecule receptor material L8-BO used in the present invention is as follows:

[0053]

[0054] Example 2

[0055] The preparation method of the ternary random conjugated polymer based on pyrazine-2-carboxylate unit, the specific reaction route is as follows:

[0056]

[0057] The specific operations are as follows:

[0058] In a 10mL microwave reaction tube, 0.1mmol of ditin monomer M1, 0.95mmol of dibrominated monomer M2, 0.05mmol of dibrominated monomer M3, 0.003mmol of Pd2(dba)3, 0.03mmol of P(o-tol)3 and 2mL of anhydrous toluene were added, and the reaction mixture was stirred and reacted at 150°C for 1.5 hours under microwave heating. After the polymerization, the reaction mixture was precipitated in 100mL of methanol, and the solid was collected by filtration. Soxhlet extraction was performed with acetone, n-hexane, dichloromethane, chloroform and chlorobenzene, respectively. The chlorobenzene extract was concentrated and precipitated in 100mL of methanol to obtain a solid polymer. Finally, the solid was vacuum dried at 55°C for 10h to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylate units.

[0059] like Figure 4 The obtained polymer was treated with trichlorobenzene as solvent and its number average molecular weight (M n ) is 72.7 kDa and the dispersion index (PDI) is 2.07.

[0060] Preparation and performance testing of organic solar cell devices: Commercially purchased indium tin oxide (ITO) glass was cleaned with detergent, water, deionized water, acetone, and isopropanol in turn, and then dried and spin-coated with a 30 nm thick PEDOT:PSS as an anode modification layer for standby use. A chloroform mixed solution of the ternary conjugated polymer based on pyrazine-2-carboxylate unit and the small molecule electron acceptor material L8-BO (weight ratio of 1:1.2) in Example 2 (the concentration of the ternary conjugated polymer based on pyrazine-2-carboxylate unit prepared in Example 2 in the mixed solution is 6 mg / mL) was spin-coated on the PEDOT:PSS anode modification layer to form the active layer of the device (thickness of 100 nm). Finally, a layer of PNDIT-F3N with a thickness of 10 nm was spin-coated as a cathode modification layer and Ag (100 nm) as the device cathode to obtain a polymer solar cell device. The effective area of ​​the photovoltaic device is 0.049 cm 2 , at 100mW / cm 2 The photovoltaic performance of the device was tested under light intensity, and the three parameters of the polymer solar cell device, open circuit voltage, short circuit current and fill factor, were obtained. Its JV curve is shown in Figure 5 , where the open circuit voltage of the polymer solar cell device is V oc =0.95V, short circuit current J sc =25.0mA / cm 2 , filling factor FF=65.6%, conversion efficiency PCE=15.6%.

[0061] The structure of the small molecule receptor material L8-BO used in the present invention is as follows:

[0062]

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention prepares a new type of ternary random conjugated polymer based on pyrazine-2-carboxylate unit base, which is easy to synthesize, has a high yield and good thermal stability. This type of polymer has well-regulated molecular energy levels, strong absorption spectra and high charge transfer performance, and is suitable as an electron donor material for the preparation of organic solar cells.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A ternary random conjugated polymer based on pyrazine-2-carboxylate units, characterized in that: It has the structure shown in the following general formula I: Among them, in the general formula Ⅰ, R1, R2, R3, R4 and R5 are each independently selected from hydrogen, an alkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a siloxane group, an ester group, an aryl group, an aralkyl group, a haloalkyl group, a heteroalkyl group or an alkenyl group; X is independently selected from one of hydrogen and halogen atoms; n represents the number of repeating units of the polymer, which is selected from a natural number between 1 and 5000; y is 0.01 to 0.99, and x+y=1.

2. The ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 1, characterized in that: In the general formula I, R1, R2, R3, R4 and R5 are each independently selected from an alkyl group having 1 to 40 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a siloxane group, an ester group; X is selected from F or Cl; In the general formula I, y is 0.05-0.

5.

3. The ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 1, characterized in that: The number average molecular weight of the ternary random conjugated polymer based on pyrazine-2-carboxylate units is 1,000 to 1,000,000, preferably 20,000 to 500,000.

4. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 1, comprising the following steps: The compound represented by formula II, the compound represented by formula III and the compound represented by formula IV are subjected to a ternary random copolymerization reaction under the action of a catalyst to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylate units; in, In the compound represented by Formula II, the substituents R1 and X are the same as the substituents R1 and X in Formula I; Y1 is selected from any one of a boric acid group, a zinc halide group or a trialkyltin group; In the compound represented by formula III, the substituent R2 is the same as the substituent R2 in the general formula I; Y2 is selected from one of I, Br or Cl; In the compound represented by formula IV, the substituents R3, R4 and R5 are the same as the substituents R3, R4 and R5 in the general formula I; and Y3 is selected from one of I, Br or Cl.

5. The method for preparing a ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 4, characterized in that: The boronic acid group is selected from one of 1,3,2-dioxaborolane-2-yl, 4,4,5,5-tetramethyl-1,2,3-dioxaborolane-2-yl or 5,5-dimethyl-1,3,2-dioxaborolane-2-yl; the zinc halide group is selected from zinc chloride or zinc bromide; the trialkyltin group is selected from one of trimethyltin, triethyltin or tributyltin.

6. The method for preparing a ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 4, characterized in that: The catalyst is any one of [1,3-bis(diphenylphosphino)propane]dichloronickel, tetrakis(triphenylphosphine)palladium, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate; the molar ratio of the catalyst to the compound represented by formula II is 0.001-0.5:1, preferably 0.01-0.1:

1.

7. The method for preparing a ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 4, characterized in that: A catalyst ligand is also added to the reaction system. The catalyst ligand is any one of tri(o-methylphenyl)phosphine, tributylphosphine or tricyclohexylphosphine. The molar ratio of the catalyst to the catalyst ligand is 1:1-20, preferably 1:2-10.

8. The method for preparing a ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 4, characterized in that: The molar ratio of the compound represented by formula III to the compound represented by formula IV is 99:1 to 1:99, and more preferably 95:5 to 50:50; the ratio of the total molar number of the compound represented by formula III and the compound represented by formula IV to the molar number of the compound represented by formula II is 1:

1.

9. The method for preparing a ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 4, characterized in that: The copolymerization reaction is carried out in a solvent, and the solvent is any one of anhydrous toluene, anhydrous chlorobenzene, and anhydrous o-xylene; the ratio of the volume of the solvent to the molar number of the compound represented by formula II is 10-100 mL: 1 mmol; The copolymerization reaction temperature is 80 to 200° C., preferably 100 to 150° C., and the heating method is oil bath heating or microwave heating; the reaction time is 0.5 to 48 hours; and the copolymerization reaction is carried out under argon protection; The post-treatment steps of the reaction liquid obtained by the copolymerization reaction are as follows: the reaction mixture is precipitated in methanol, the solid is collected by filtration, and Soxhlet extraction is performed with acetone, n-hexane, dichloromethane, chloroform, and chlorobenzene respectively, the chlorobenzene extract is concentrated and then precipitated in methanol to obtain a solid polymer, which is filtered and the obtained solid is vacuum dried at 50-60° C. for 3-24 hours.

10. Use of the ternary random conjugated polymer based on pyrazine-2-carboxylate units according to claim 1 in thin film semiconductor devices, electrochemical devices, photovoltaic devices and photoelectric devices.

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