A ternary random conjugated polymer based on pyrazine-2-carboxylate unit and preparation method and application thereof

Abstract

This invention provides a ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units, its preparation method, and its application. The ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units of this invention has the structure shown in General Formula I. This ternary random conjugated polymer has advantages such as good light absorption and suitable electronic energy levels. It can effectively reduce the energy level of the polymer without significantly affecting the polymer's optical band gap, thereby improving the open-circuit voltage and photoelectric conversion efficiency of the device.

Description

Technical Field

[0001] This invention belongs to the field of molecular technology, specifically relating to a ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units, its preparation method, and its application. Background Technology

[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. Lin, F. Qi, T. Heumüller, A. Distler, H.-J. Egelhaaf, N. Li, PCY Chow, CJ Brabec, AKY Jen, H.-L. Yip, Chem. Rev. 2022, 122, 14180; J. Yi, G. Zhang, H. Yu, H. Yan, Nat. Rev. Mater. 2023, 9, 46.). To date, OSCs have achieved a power conversion efficiency (PCE) of 20%. The highest-performing devices often utilize Y-series non-fullerene small molecule acceptors, paired 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.). To further advance OSC development, designing more efficient wide-bandgap polymer donors and expanding the high-performance donor family are of great significance.

[0003] The ternary copolymer strategy introduces a third component into high-performance donor polymers. By controlling the proportion of the third component, the fundamental properties of the material, such as energy levels, absorption spectra, aggregation, and crystallinity, can be effectively tuned. This inevitably leads to molecular disorder, increases main-chain entropy, and reduces the crystallization tendency of the ternary copolymer. However, the intermolecular binding forces imparted by the secondary bonding of the ester, cyano, chlorinated, and fluorinated third components can successfully counteract 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, TKLau, 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, by selecting appropriate donor-acceptor unit types and developing novel donor materials, the energy conversion efficiency can be significantly improved, which is of great significance for enhancing the performance of solar cells. This invention is proposed for this purpose. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units, its preparation method, and its applications. The ternary random conjugated polymer of this invention possesses advantages such as good light absorption and suitable electronic energy levels. It can effectively reduce the energy level of the polymer without significantly affecting the polymer's optical band gap, 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-carboxylic acid ester units has the structure shown in general formula I:

[0008]

[0009] In general formula I,

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

[0011] X is independently selected from hydrogen or halogen atoms;

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

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

[0014] According to a preferred embodiment of the present invention, in the general formula I, R1, R2, R3, R4 and R5 are each independently selected from alkyl groups having 1-40 carbon atoms, alkoxy groups having 1-30 carbon atoms, siloxane groups, and ester groups; X is selected from F or Cl.

[0015] According to a preferred embodiment of the present invention, in the general formula I, y is 0.05-0.5.

[0016] According to a preferred embodiment of the present invention, the number-average molecular weight of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester 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-carboxylic acid ester units includes the following steps:

[0018] The compounds shown in Formula II, Formula III, and Formula IV were subjected to a ternary random copolymerization reaction under the action of a catalyst to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units.

[0019]

[0020] in,

[0021] In the compound shown in Formula II, the substituents R1,X are the same as those in general Formula I; Y1 is selected from any one of borate groups, zinc halide groups, or trialkyltin groups.

[0022] In the compound shown in Formula III, the substituent R2 is the same as the substituent R2 in general Formula I; Y2 is selected from I, Br or Cl;

[0023] In the compound shown in Formula IV, the substituents R3, R4, and R5 are the same as those in Formula I; Y3 is selected from I, Br, or Cl.

[0024] According to a preferred embodiment of the present invention, the borate group is selected from one of 1,3,2-dioxaborane-2-yl, 4,4,5,5-tetramethyl-1,2,3-dioxacyclopentaborane-2-yl, or 5,5-dimethyl-1,3,2-dioxaborane-2-yl; the zinc halide group is selected from zinc chloride or zinc bromide; and the trialkyltin group is selected from one of trimethyltin, triethyltin, or tributyltin.

[0025] According to a preferred embodiment of the present invention, the catalyst is any one of [1,3-bis(diphenylphosphine)propane]dichloronickel, tetra(triphenylphosphine)palladium, [1,2-bis(diphenylphosphine)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride, or palladium acetate; the molar ratio of the catalyst to the compound shown in Formula II is 0.001-0.5:1, more preferably 0.01-0.1:1.

[0026] According to a preferred embodiment of the present invention, a catalyst ligand is further added to the reaction system, wherein the catalyst ligand is any one of tris(o-methylphenyl)phosphine, tributylphosphine, or tricyclohexylphosphine, and the molar ratio of the catalyst to the catalyst ligand is 1:1-20, more preferably 1:2-10.

[0027] According to a preferred embodiment of the present invention, the molar ratio of the compound shown in Formula III to the compound shown in Formula IV is 99:1 to 1:99, more preferably 95:5 to 50:50; the ratio of the total molar number of the compound shown in Formula III and the compound shown in Formula IV to the molar number of the compound shown in Formula II is 1:1.

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

[0029] According to a preferred embodiment of the present invention, the temperature of the copolymerization reaction is 80–200°C, more preferably 100–150°C, and the heating method is oil bath heating or microwave heating; the reaction time is 0.5–48 hours; and the copolymerization reaction is carried out under argon protection.

[0030] According to a preferred embodiment of the present invention, the post-treatment steps of the reaction solution obtained from 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, trichloromethane, and chlorobenzene, respectively. The chlorobenzene extract is concentrated and then precipitated in methanol to obtain a solid polymer. The polymer 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-carboxylic acid ester unit is used in thin film semiconductor devices, electrochemical devices, photovoltaic devices and optoelectronic 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 including a bulk heterojunction structure.

[0032] The present invention comprises a semiconductor composition and a dopant based on a pyrazine-2-carboxylic acid ester unit-based ternary random conjugated polymer; the dopant is selected from fullerene derivatives or non-fullerene N-type organic semiconductors.

[0033] When a ternary conjugated polymer based on a pyrazine-2-carboxylic acid ester unit 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, wherein the photovoltaic material layer contains the conjugated polymer; when a conjugated polymer based on a pyrazine-2-carboxylic acid ester unit is used in an optoelectronic device, the optoelectronic device includes a first electrode, a second electrode spaced apart from the first electrode, and at least one active material layer disposed between the first electrode and the second electrode; wherein the active material layer contains the conjugated polymer.

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

[0035] This invention provides a ternary conjugated polymer based on pyrazine-2-carboxylic acid ester units. By introducing pyrazine-2-carboxylic acid ester units with specific structures as a third component into the main chain of a DA conjugated polymer (e.g., D18), a ternary random conjugated polymer is obtained. The properties of the polymer material are controlled by adjusting the functional group modification or alkyl chain length on the acceptor unit. As a result, the polymer has a lower electronic energy level, better molecular arrangement, higher hole mobility, and better photovoltaic device performance without significantly affecting the polymer optical bandgap. The polymer of this invention has advantages such as good light absorption and suitable electronic energy level. It can effectively reduce the energy level of the polymer without significantly affecting the polymer optical bandgap, thereby improving the open-circuit voltage and photoelectric conversion efficiency of the device. Attached Figure Description

[0036] Figure 1 Gel permeation chromatogram of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units prepared in Example 1;

[0037] Figure 2 The UV-Vis absorption spectrum of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units prepared in Example 1 is shown.

[0038] Figure 3The JV curve of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units prepared in Example 1 applied to an organic solar cell;

[0039] Figure 4 The gel permeation chromatogram of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units prepared in Example 2;

[0040] Figure 5 The JV curve of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester unit prepared in Example 2 applied to an organic solar cell. Detailed Implementation

[0041] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of 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 phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Secondly, this invention is described in detail using structural diagrams, etc. When detailing the embodiments of this invention, for ease of explanation, the diagrams may be partially enlarged, deviating from the general scale. Furthermore, the diagrams are merely examples and should not limit the scope of protection of this invention. In addition, actual manufacturing should include three-dimensional space with length, width, and depth.

[0044] Example 1

[0045] The preparation method of ternary random conjugated polymers based on pyrazine-2-carboxylic acid ester units, with the specific reaction route as follows:

[0046]

[0047] The specific steps are as follows:

[0048] In a 25 mL two-necked round-bottom flask, 0.1 mmol of bistin monomer M1, 0.08 mmol of bisbromo monomer M2, 0.02 mmol of bisbromo monomer M3, 0.002 mmol of Pd2(dba)3, 0.008 mmol of P(o-tol)3, and 5 mL of anhydrous toluene were added. The reaction mixture was purged with 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 polymerization, the reaction mixture was settled in 100 mL of methanol, and the solid was collected by filtration. The solid was extracted with acetone, n-hexane, dichloromethane, trichloromethane, and chlorobenzene, respectively, by Soxhlet extraction. The chlorobenzene extract was concentrated and settled in 100 mL of methanol to obtain a solid polymer. Finally, the solid was dried under vacuum at 55 °C for 10 h to obtain a ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units.

[0049] like Figure 1 As shown, the number-average molecular weight (M) of the obtained polymer was determined by gel permeation chromatography using trichlorobenzene as a solvent. n The value is 47.3 kDa, and the dispersion (PDI) is 2.13.

[0050] UV-Vis absorption spectroscopy: For the absorption spectra of the solution, chloroform was used as the solvent. The polymer was prepared as a 2 mg / mL solution. For the thin film absorption sample, a 10 mg / mL polymer chloroform solution was spin-coated onto a quartz plate at 3000 rpm for 30 s. The absorption spectra of the polymer in chloroform solution and thin film states are shown below. Figure 2 The absorption spectra of the polymer in chloroform solution and in thin film are shown. The maximum absorption positions of the polymer in solution and thin film are 579 nm and 578 nm, respectively.

[0051] Fabrication and performance testing of organic solar cell devices: Commercially purchased indium tin oxide (ITO) glass was ultrasonically cleaned sequentially with detergent, water, deionized water, acetone, and isopropanol. After drying, a 30 nm thick layer of PEDOT:PSS was spin-coated as the anode modification layer. A chloroform blend solution of the pyrazine-2-carboxylic acid ester-based ternary conjugated polymer and the small molecule electron acceptor material L8-BO (weight ratio 1:1.2) from Example 1 (the concentration of the pyrazine-2-carboxylic acid ester-based ternary conjugated polymer prepared in Example 1 was 7 mg / mL) was spin-coated onto the PEDOT:PSS anode modification layer to form the active layer of the device (100 nm thick). Finally, a 10 nm thick layer of PNDIT-F3N was spin-coated as the cathode modification layer, and Ag (100 nm) was spin-coated as the cathode to obtain the polymer solar cell device. The effective area of ​​the photovoltaic device was 0.049 cm². 2 At 100mW / cm 2Photovoltaic performance tests were conducted on the device under varying light intensity to obtain three parameters of the polymer solar cell: open-circuit voltage, short-circuit current, and fill factor. Its JV curve is shown below. Figure 3 The open-circuit voltage V of the polymer solar cell device oc =0.94V, short-circuit current J sc =26.1mA / cm 2 The fill factor FF = 69.4% and the conversion efficiency PCE = 17.0%.

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

[0053]

[0054] Example 2

[0055] The preparation method of ternary random conjugated polymers based on pyrazine-2-carboxylic acid ester units, with the specific reaction route as follows:

[0056]

[0057] The specific steps are as follows:

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

[0059] like Figure 4 As shown, the number-average molecular weight (M) of the obtained polymer was determined by gel permeation chromatography using trichlorobenzene as a solvent. n The value is 72.7 kDa, and the dispersion (PDI) is 2.07.

[0060] Fabrication and performance testing of organic solar cell devices: Commercially purchased indium tin oxide (ITO) glass was sequentially ultrasonically cleaned with detergent, water, deionized water, acetone, and isopropanol. After drying, a 30 nm thick layer of PEDOT:PSS was spin-coated as the anode modification layer. A chloroform blend solution of the pyrazine-2-carboxylic acid ester-based ternary conjugated polymer and the small molecule electron acceptor material L8-BO (weight ratio 1:1.2) from Example 2 (the concentration of the pyrazine-2-carboxylic acid ester-based ternary conjugated polymer in the blend solution was 6 mg / mL) was spin-coated onto the PEDOT:PSS anode modification layer to form the active layer (100 nm thick) of the device. Finally, a 10 nm thick layer of PNDIT-F3N was spin-coated as the cathode modification layer, and Ag (100 nm) was spin-coated as the cathode to obtain the polymer solar cell device. The effective area of ​​the photovoltaic device was 0.049 cm². 2 At 100mW / cm 2 Photovoltaic performance tests were conducted on the device under varying light intensity to obtain three parameters of the polymer solar cell: open-circuit voltage, short-circuit current, and fill factor. Its JV curve is shown below. Figure 5 The open-circuit voltage V of the polymer solar cell device oc =0.95V, short-circuit current J sc =25.0mA / cm 2 The fill factor FF = 65.6% and the conversion efficiency PCE = 15.6%.

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

[0062]

[0063] Compared with the prior art, the beneficial effects of the present invention are: the present invention prepares a new type of ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester unit, which is easy to synthesize, has high yield and good thermal stability. This type of polymer has well-tunable molecular energy levels, strong absorption spectra and high charge transport 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 and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units, characterized in that, It has the structure shown in general formula I: Ⅰ In general formula I, R1, R2, R3, and R4 are each independently selected from hydrogen, alkyl groups having 1-40 carbon atoms, alkoxy groups having 1-30 carbon atoms, siloxane groups, ester groups, aryl groups, aralkyl groups, haloalkyl groups, heteroalkyl groups, or alkenyl groups; R5 is a siloxane group. X is independently selected from hydrogen or halogen atoms; n represents the number of repeating units in the polymer, selected from natural numbers between 1 and 5000; y is between 0.01 and 0.99, and x + y = 1; The number-average molecular weight of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units is between 1,000 and 1,000,000.

2. The ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 1, characterized in that, In the general formula I, X is selected from F or Cl; y is 0.05-0.

5.

3. The ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 1, characterized in that, The number-average molecular weight of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units is between 20,000 and 500,000.

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

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

6. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 4, characterized in that, The catalyst is any one of [1,3-bis(diphenylphosphine)propane]dichloronickel, tetra(triphenylphosphine)palladium, [1,2-bis(diphenylphosphine)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride, or palladium acetate; the molar ratio of the catalyst to the compound shown in Formula II is 0.001-0.5:

1.

7. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester 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 tris(o-methylphenyl)phosphine, tributylphosphine, or tricyclohexylphosphine, and the molar ratio of the catalyst to the catalyst ligand is 1:1-20.

8. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 4, characterized in that, The molar ratio of the compound shown in Formula III to the compound shown in Formula IV is 99:1 to 1:99; the ratio of the total number of moles of the compound shown in Formula III and the compound shown in Formula IV to the number of moles of the compound shown in Formula II is 1:

1.

9. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 4, characterized in that, The molar ratio of the compound shown in Formula III to the compound shown in Formula IV is 95:5 to 50:

50.

10. The method for preparing the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units according to claim 4, characterized in that, The copolymerization reaction is carried out in a solvent, which is any one of anhydrous toluene, anhydrous chlorobenzene, and anhydrous o-xylene; the volume ratio of the solvent to the molar number of the compound shown in Formula II is 10-100 mL: 1 mmol. The copolymerization reaction is carried out at a temperature of 80~200℃, using oil bath heating or microwave heating; the reaction time is 0.5~48 hours; the copolymerization reaction is conducted under argon protection. The post-processing steps of the reaction solution obtained from 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, trichloromethane and chlorobenzene respectively. The chlorobenzene extract is concentrated and then precipitated in methanol to obtain solid polymer. The solid is filtered and then vacuum dried at 50~60℃ for 3~24 hours.

11. The application of the ternary random conjugated polymer based on pyrazine-2-carboxylic acid ester units as described in claim 1 in thin-film semiconductor devices, electrochemical devices, photovoltaic devices and optoelectronic devices.

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